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https://www.transtutors.com/questions/is-deprotonated-by-very-strong-bases-write-resonance-forms-to-show-the-stabilization-3923743.htm | # Is deprotonated by very strong bases? Write resonance forms to show the stabilization of the...
Is deprotonated by very strong bases? Write resonance forms to show the stabilization of the carbanion those results.
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https://www.physicsforums.com/threads/simply-connected-curve.492409/ | # Simply connected curve
1. ### saravanan13
56
Dear Friends
In the complex functions, I completely understand the simply connected region but not the multiply connected region?
An apple is a simply connected region but No. 8 is multiply connected. How?
2. ### lavinia
1,934
Simply connected means that every closed curve can be shrunk to a point. On the figure eight there are infinitely many curves that can not be shrunk to a point. Also on a circle.
A disk minus a point is not simply connected. For instance look at a branch of the logarithm in the unit disk minus the origin.
3. ### saravanan13
56
Thank
I could not follow your Second statement. Especially " branch of logarithm". Why cant a circle be simply connected?
4. ### lavinia
1,934
The angle function on a circle is defined only locally but its exterior derivative is globally defined. Therefore it is a closed 1 form that is not the exterior derivative of a function.
The integral of the derivative of the complex logarithm around a circle centered at the origin is the same as the integral of the angle function.
Another way to look at this is - suppose the curve that loops around the circle once were null homotopic. Then there would be a map from a disk to the circle that was equal to this curve on the boundary of the disk. Stokes Theorem then tells you that the integral of the exterior derivative of the angle function over this loop must be zero. But the intergral is not zero. It is 2pi.
I suggest that you look at the covering space argument that also proves that the circle is not simply connected. This avoids homology and uses purely topological arguments.
Intuitively, a null homotopic loop on the circle would have to retrace its path and return to its end point in the opposite direction that it came in. The loop that goes around once does not do this.
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https://worldwidescience.org/topicpages/a/americium+bromides.html | Sample records for americium bromides
1. Preparation of americium amalgam
International Nuclear Information System (INIS)
The authors describe a method for the electrochemical preparation of an americium amalgam from americium dioxide and americium 241 and 243 for use in determining the physicochemical properties of the alloy. Moessbauer spectra were made using neptunium dioxide, in the neptunium 237 form, as an absorber. Results show that electrolysis produces a homogeneous amalgam that gives an unoxidized product on vacuum distillation at 200 degrees C
2. Preparation of americium amalgam
International Nuclear Information System (INIS)
Using the method of NGR-spectroscopy with the aid of 241Am isotope chemical state of transuranium elements in the volume and on the surface of amalgams is studied. Amalgam preparation was realized in a simplified electrolytic cell. It is shown that in the process of amalgam preparation the first order of reaction as to actinide is observed; americium is distributed gradually over the volume and it is partially sorbed by the surface of glass capillary. NGR spectrum of dry residue after mercury distillation at 200 deg C points to the presence of americium-mercury intermetal compounds
3. 1976 Hanford americium accident
Energy Technology Data Exchange (ETDEWEB)
Heid, K R; Breitenstein, B D; Palmer, H E; McMurray, B J; Wald, N
1979-01-01
This report presents the 2.5-year medical course of a 64-year-old Hanford nuclear chemical operator who was involved in an accident in an americium recovery facility in August 1976. He was heavily externally contaminated with americium, sustained a substantial internal deposition of this isotope, and was burned with concentrated nitric acid and injured by flying debris about the face and neck. The medical care given the patient, including the decontamination efforts and clinical laboratory studies, are discussed. In-vivo measurements were used to estimate the dose rates and the accumulated doses to body organs. Urinary and fecal excreta were collected and analyzed for americium content. Interpretation of these data was complicated by the fact that the intake resulted both from inhalation and from solubilization of the americium embedded in facial tissues. A total of 1100 ..mu..Ci was excreted in urine and feces during the first 2 years following the accident. The long-term use of diethylenetriaminepentate (DTPA), used principally as the zinc salt, is discussed including the method, route of administration, and effectiveness. To date, the patient has apparently experienced no complications attributable to this extensive course of therapy, even though he has been given approximately 560 grams of DTPA. 4 figures, 1 table.
4. Chemistry of americium
Energy Technology Data Exchange (ETDEWEB)
Schulz, W.W.
1976-01-01
Essential features of the descriptive chemistry of americium are reviewed. Chapter titles are: discovery, atomic and nuclear properties, collateral reading, production and uses, chemistry in aqueous solution, metal, alloys, and compounds, and, recovery, separation, purification. Author and subject indexes are included. (JCB)
5. The Biokinetic Model of Americium
Institute of Scientific and Technical Information of China (English)
2011-01-01
To improve in vivo measurements for detecting internal exposure from transuranium radio nuclides, such as neptunium, plutonium, americium, the bioknetic model was studied. According to ICRP report (1993, 1995, 1997) and other research, the
6. Americium product solidification and disposal
International Nuclear Information System (INIS)
The americium product from the TRUEX processing plant needs to be converted into a form suitable for ultimate disposal. An evaluation of the disposal based on safety, number of process steps, demonstrated operability of the processes, production of low-level alpha waste streams, and simplicity of maintenance with low radiation exposures to personnel during maintenance, has been made. The best process is to load the americium on a cation exchange resin followed by calcination or oxidation of the resin after loading
7. Spectrochemical analysis of curium and americium samples
International Nuclear Information System (INIS)
Spectrochemical procedures have been developed to determine impurities in americium and curium samples. The simultaneous separation of many impurity elements from the base material (americium and curium) is carried out with extraction and extraction-chromatographic methods using di-2-ethylhexylphosphoric acid. It is shown that part of the elements are separated with extraction or sorption of americium and curium; the other part with the Talspeak process. Two fractions in the extraction chromatography and three fractions in the extraction separation of americium and curium, containing impurities, are analyzed separately by a.c. or d.c. arc spectrography. To increase the sensitivity of the spectrographic analysis and accelerate the burn-up of impurities from the crater of the carbon electrode bismuth fluoride and sodium chloride were used as chemically active substances. The extraction of impurities from weighed quantities of americium and curium samples of 5 to 10 mg permits the lower limit of determined impurity concentrations to be extended to 1 x 10-4 to 5 x 10-3% m/m. (author)
8. Pyrochemical technology of plutonium and americium preparation and purification
International Nuclear Information System (INIS)
Pyrochemical tecnology of metallic plutonium and americium preparation and purification is considered. Investigations into plutonium dioxide reduction up to metal; plutonium electrolytic refining in molten salts; plutonium extraction from the molten salts and preparation of americium dioxide and metallic americium from its tetrafluoride are described
9. Aqueous Chloride Operations Overview: Plutonium and Americium Purification/Recovery
Energy Technology Data Exchange (ETDEWEB)
Kimball, David Bryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Skidmore, Bradley Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-06-22
Acqueous Chloride mission is to recover plutonium and americium from pyrochemical residues (undesirable form for utilization and storage) and generate plutonium oxide and americium oxide. Plutonium oxide is recycled into Pu metal production flowsheet. It is suitable for storage. Americium oxide is a valuable product, sold through the DOE-OS isotope sales program.
10. 1976 Hanford americium exposure incident: psychological aspects
International Nuclear Information System (INIS)
Accidents involving exposure to radiation or radioactive materials may involve an unusual degree of emotional trauma. Methods that may be employed in dealing with such trauma are discussed in relation to a specific accident in which a radiation worker was injured and seriously contaminated with americium-241
11. Incentives for transmutation of americium in thermal reactors
International Nuclear Information System (INIS)
12. Surface complexation modeling of americium sorption onto volcanic tuff.
Science.gov (United States)
Ding, M; Kelkar, S; Meijer, A
2014-10-01
Results of a surface complexation model (SCM) for americium sorption on volcanic rocks (devitrified and zeolitic tuff) are presented. The model was developed using PHREEQC and based on laboratory data for americium sorption on quartz. Available data for sorption of americium on quartz as a function of pH in dilute groundwater can be modeled with two surface reactions involving an americium sulfate and an americium carbonate complex. It was assumed in applying the model to volcanic rocks from Yucca Mountain, that the surface properties of volcanic rocks can be represented by a quartz surface. Using groundwaters compositionally representative of Yucca Mountain, americium sorption distribution coefficient (Kd, L/Kg) values were calculated as function of pH. These Kd values are close to the experimentally determined Kd values for americium sorption on volcanic rocks, decreasing with increasing pH in the pH range from 7 to 9. The surface complexation constants, derived in this study, allow prediction of sorption of americium in a natural complex system, taking into account the inherent uncertainty associated with geochemical conditions that occur along transport pathways.
13. Rapacuronium bromide (Organon Teknika).
Science.gov (United States)
Plowman, A N
1999-07-01
Organon Teknika's rapacuronium bromide (Org-9487), the 16-N-allyl, 17-beta-propionate analog of vecuronium bromide, is in phase III clinical trials in the US and Europe for potential use as an anesthetic. It is a steroidal neuromuscular blocking drug characterized by low potency, rapid rate of block development and short time course of neuromuscular blocking action as compared with other non-depolarizing compounds [170210,221422]. A multicenter, randomized, assessor-blind, placebo-controlled, dose-finding study in patients undergoing tracheal intubation showed that the drug produced a dose dependent neuromuscular block. Doses of 1.5 to 2 mg/kg allowed rapid intubation and short duration of action [273336]. Another study showed that the drug does not cause cardiovascular side-effects [273336]. A meeting was held in Europe on 8 February 1999 to brief company employees on the registration and release of rapacuronium [319211] for which the company anticipates a launch in late 1999 [320706]. Organon estimates that the market value of Org-9487 is between dollar 100 m and dollar 250 m a year, each for Europe and the US [221422].
14. Electrochemical oxidation of americium in nitric medium: study of reaction mechanisms; Oxydation de l'americium par voie electrochimique: etude des mecanismes
Energy Technology Data Exchange (ETDEWEB)
Picart, S.; Chartier, D.; Donnet, L.; Adnet, J.M. [CEA Valrho, (DCC/DRRV/SPHA), 30 - Marcoule (France)
2000-07-01
One alternative selected by the CEA for partitioning minor actinides from aqueous solutions containing fission products is the selective extraction of oxidized americium. This is the SESAME process (Selective Extraction and Separation of Americium by Means of Electrolysis) aimed to convert americium to oxidation state (VI) and then extract it with a specific extractant of high valences. This paper presents the study of the electrochemical oxidation of americium in nitric medium which represents an important stage of the process. The reaction can be divided into two main steps: oxidation of americium (III) to americium (IV), and then of americium (IV) to americium (VI). For the first oxidation step, a ligand L is needed to stabilize the intermediate species americium (IV) which disproportionates in its free form into americium (III) and (V). Phospho-tungstate or silico-tungstate are appropriate ligands because they are stable in concentrated nitric acid and show a great affinity for metallic cations at oxidation state (IV) (Table 1 lists the stability constants of americium (IV) complexes). The presence of the lacunary poly-anion lowers the potential of the americium (IV) / americium (Ill) redox pair (see Figure 5 for the diagram of the apparent formal potential of americium versus ligand concentration). This makes it thermodynamically possible to oxidize americium (III) into americium (IV) at the anode of an electrolyzer in nitric acid. For the second oxidation step, a strong oxidant redox mediator, like silver (II), is needed to convert complexed americium at oxidation state (IV) to oxidation state (V). The AmVL complex is then hydrolyzed to yield americyle (V) aqua ion. A spectroscopic Raman study with {sup 18}O labeled species showed that the oxygen atoms of the americyle moiety came from water. This indicates that water hydrolyzes the americium (V) complex to produce americyle (V) aqua ion, AmO{sub 2}{sup +}. This cation reacts with silver (Il) to give
15. Higher Americium Oxidation State Research Roadmap
Energy Technology Data Exchange (ETDEWEB)
Mincher, Bruce J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Law, Jack D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Goff, George S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moyer, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Burns, Jon D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lumetta, Gregg J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sinkov, Sergey I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shehee, Thomas C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hobbs, David T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
2015-12-18
The partitioning of hexavalent Am from dissolved nuclear fuel requires the ability to efficiently oxidize Am(III) to Am(VI) and to maintain that oxidation state for a length of time sufficient to perform the separation. Several oxidants have been, or are being developed. Chemical oxidants include Ag-catalyzed ozone, Ag-catalyzed peroxydisulfate, Cu(III) periodate, and sodium bismuthate. Hexavalent americium has also now successfully been prepared by electrolysis, using functionalized electrodes. So-called auto-reduction rates of Am(VI) are sufficiently slow to allow for separations. However, for separations based on solvent extraction or ion exchange using organic resins, the high valence state must be maintained under the reducing conditions of the organic phase contact, and a holding oxidant is probably necessary. Until now, only Cu(III) periodate and sodium bismuthate oxidation have been successfully combined with solvent extraction separations. Bismuthate oxidation provided the higher DAm, since it acts as its own holding oxidant, and a successful hot test using centrifugal contactors was performed. For the other oxidants, Ag-catalyzed peroxydisulfate will not oxidize americium in nitric acid concentrations above 0.3 M, and it is not being further investigated. Peroxydisulfate in the absence of Ag catalysis is being used to prepare Am(V) in ion exchange work, discussed below. Preliminary work with Ag-catalyzed ozone has been unsuccessful for extractions of Am(VI) from 6.5 M HNO3, and only one attempt at extraction, also from 6.5 M HNO3, using the electrolytic oxidation has been attempted. However, this high acid concentration was based on the highest Am extraction efficiency using the bismuthate oxidant; which is only sparingly soluble, and thus the oxidation yield is based on bismuthate solubility. Lower acid concentrations may be sufficient with alternative oxidants and work with Ag-ozone, Cu(III) and electrolysis is on-going. Two non
16. Methylnaltrexone bromide methanol monosolvate
Directory of Open Access Journals (Sweden)
Xinbo Zhou
2012-03-01
Full Text Available In the title compound [systematic name: (4R,4aS,7aR,12bS-3-cyclopropylmethyl-4a,9-hydroxy-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-3-ium bromide methanol monosolvate], C21H26NO4+·Br−·CH3OH, two of the three six-membered rings adopt chair conformations while the third, which contains a C=C double bond, adopts an approximate half-boat conformation. The 2,3-dihydrofuran ring adopts an envelope conformation. In the crystal, the components are linked by O—H...O and O—H...Br hydrogen bonds. The absolute stereochemistry was inferred from one of the starting materials.
17. Iron bromide vapor laser
Science.gov (United States)
Sukhanov, V. B.; Shiyanov, D. V.; Trigub, M. V.; Dimaki, V. A.; Evtushenko, G. S.
2016-03-01
We have studied the characteristics of a pulsed gas-discharge laser on iron bromide vapor generating radiation with a wavelength of 452.9 nm at a pulse repetition frequency (PRF) of 5-30 kHz. The maximum output power amounted to 10 mW at a PRF within 5-15 kHz for a voltage of 20-25 kV applied to electrodes of the discharge tube. Addition of HBr to the medium produced leveling of the radial profile of emission. Initial weak lasing at a wavelength of 868.9 nm was observed for the first time, which ceased with buildup of the main 452.9-nm line.
18. Plutonium and Americium Geochemistry at Hanford: A Site Wide Review
Energy Technology Data Exchange (ETDEWEB)
Cantrell, Kirk J.; Felmy, Andrew R.
2012-08-23
This report was produced to provide a systematic review of the state-of-knowledge of plutonium and americium geochemistry at the Hanford Site. The report integrates existing knowledge of the subsurface migration behavior of plutonium and americium at the Hanford Site with available information in the scientific literature regarding the geochemistry of plutonium and americium in systems that are environmentally relevant to the Hanford Site. As a part of the report, key research needs are identified and prioritized, with the ultimate goal of developing a science-based capability to quantitatively assess risk at sites contaminated with plutonium and americium at the Hanford Site and the impact of remediation technologies and closure strategies.
19. Mixed chelation therapy for removal of plutonium and americium
International Nuclear Information System (INIS)
Iron-binding compounds, 2,3-dihydroxybenzoic acid (DHBA), 2-hydroxybenzoic acid (HBA), and 2-(acetyloxy)benzoic acid (ABA), were tested for their ability to remove americium and plutonium from rats following intraperitioneal injection of the radionuclides as citrates (pH 5). Treatments, 2 mmol/kg, were given on days 3, 6, 10, 12 and 14 following the actinide injection. DHBA and HBA caused about a 20% decrease in liver retention of americium compared to the control value, and DHB caused a similar effect for plutonium. The above agents, co-administered with 0.5 mmol polyaminopolycarboxylic acid (PAPCA)-type chelons, did not change tissue retention of americium and plutonium from that due to the PAPCAs alone. Administration of americium and plutonium to the same rats is useful for studying removal agents since the two actinides behave independently in their biological disposition and response to removal
20. Gamma-sources on the basis of metallic americium-241
International Nuclear Information System (INIS)
A batch of gamma-radiation sources has been manufactured from metallic americium-241 of isotopic purity, its activity varying from 0.08 to 0.93 GBq. The cores of the sources are high-purity americium metal condensate on a tantalum or stainless steel substrate prepared by thermal decomposition of 241Pu-241Am alloy in a high vacuum. 7 refs., 1 tab
1. Aqueous Chloride Operations Overview: Plutonium and Americium Purification/Recovery
Energy Technology Data Exchange (ETDEWEB)
Gardner, Kyle Shelton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kimball, David Bryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Skidmore, Bradley Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-09-28
These are a set of slides intended for an information session as part of recruiting activities at Brigham Young University. It gives an overview of aqueous chloride operations, specifically on plutonium and americium purification/recovery. This presentation details the steps taken perform these processes, from plutonium size reduction, dissolution, solvent extraction, oxalate precipitation, to calcination. For Americium recovery, it details the CLEAR (chloride extraction and actinide recovery) Line, oxalate precipitation and calcination.
2. Pyrochemical investigations into recovering plutonium from americium extraction salt residues
International Nuclear Information System (INIS)
Progress into developing a pyrochemical technique for separating and recovering plutonium from spent americium extraction waste salts has concentrated on selective chemical reduction with lanthanum metal and calcium metal and on the solvent extraction of americium with calcium metal. Both techniques are effective for recovering plutonium from the waste salt, although neither appears suitable as a separation technique for recycling a plutonium stream back to mainline purification processes. 17 refs., 13 figs., 2 tabs
3. Electrochemical oxidation of americium in nitric medium: study of reaction mechanisms
International Nuclear Information System (INIS)
One alternative selected by the CEA for partitioning minor actinides from aqueous solutions containing fission products is the selective extraction of oxidized americium. This is the SESAME process (Selective Extraction and Separation of Americium by Means of Electrolysis) aimed to convert americium to oxidation state (VI) and then extract it with a specific extractant of high valences. This paper presents the study of the electrochemical oxidation of americium in nitric medium which represents an important stage of the process. The reaction can be divided into two main steps: oxidation of americium (III) to americium (IV), and then of americium (IV) to americium (VI). For the first oxidation step, a ligand L is needed to stabilize the intermediate species americium (IV) which disproportionates in its free form into americium (III) and (V). Phospho-tungstate or silico-tungstate are appropriate ligands because they are stable in concentrated nitric acid and show a great affinity for metallic cations at oxidation state (IV) (Table 1 lists the stability constants of americium (IV) complexes). The presence of the lacunary poly-anion lowers the potential of the americium (IV) / americium (Ill) redox pair (see Figure 5 for the diagram of the apparent formal potential of americium versus ligand concentration). This makes it thermodynamically possible to oxidize americium (III) into americium (IV) at the anode of an electrolyzer in nitric acid. For the second oxidation step, a strong oxidant redox mediator, like silver (II), is needed to convert complexed americium at oxidation state (IV) to oxidation state (V). The AmVL complex is then hydrolyzed to yield americyle (V) aqua ion. A spectroscopic Raman study with 18O labeled species showed that the oxygen atoms of the americyle moiety came from water. This indicates that water hydrolyzes the americium (V) complex to produce americyle (V) aqua ion, AmO2+. This cation reacts with silver (Il) to give americyle (VI) ion. Figure
4. Applicability of insoluble tannin to treatment of waste containing americium
International Nuclear Information System (INIS)
The applicability of insoluble tannin adsorbent to the treatment of aqueous waste contaminated with americium has been investigated. Insoluble tannin is considered highly applicable because it consists of only carbon, hydrogen and oxygen and so its volume can be easily reduced by incineration. This report describes measurements of the americium distribution coefficient in low concentration nitric acid. The americium distribution coefficients were found to decrease with increasing concentration of nitric acid and sodium nitrate, and with increasing temperature. At 25 C in 2.0 x 10-3 M HNO3, the distribution coefficient was found to be 2000 ml g-1. The adsorption capacity was determined by column experiments using europium as a simulant of americium, and found to be 7 x 10-3 mmol g-1-dried tannin in 0.01 M HNO3 at 25 C, which corresponds to approximately 1.7 mg-241Am/g-adsorbent(dried). The prospect of applying the adsorbent to the treatment of aqueous waste contaminated with americium appears promising. (orig.)
5. Salvage of plutonium-and americium-contaminated metals
International Nuclear Information System (INIS)
Melt-slagging techniques were evaluated as a decontamination and consolidation step for metals contaminated with oxides of plutonium and americium. Experiments were performed in which mild steel, stainless steel, and nickel metals contaminated with oxides of plutonium and americium were melted in the presence of silicate slags of various compositions. The metal products were low in contamination, with the plutonium and americium strongly fractionated to the slags. Partition coefficients (plutonium in slag/plutonium in steel) of 7*10/sup 6/ with borosilicate slag and 3*10/sup 6/ for calcium, magnesium silicate slag were measured. Decontamination of metals containing as much as 14,000 p.p.m. plutonium appears to be as efficient as that of metals with plutonium levels of 400 p.p.m. Staged extraction, that is, a remelting of processed metal with clean slag, results in further decontamination of the metal. 10 refs
6. 1976 Hanford americium exposure incident: overview and perspective
International Nuclear Information System (INIS)
Salient features of the 1976 Hanford americium exposure incident are discussed. Comparisons are made with previous human and animal exposure data, and conclusions drawn relative to the injured workman, to health physics practices, and to the adequacy of current exposure limits
7. Reduction Rates for Higher Americium Oxidation States in Nitric Acid
Energy Technology Data Exchange (ETDEWEB)
Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-09-30
The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.
8. Synthesis and characterization of uranium-americium mixed oxides
International Nuclear Information System (INIS)
Americium isotopes represent a significant part of high-level and long-lived nuclear waste in spent fuels. Among the envisaged reprocessing scenarios, their transmutation in fast neutron reactors using uranium-americium mixed-oxide pellets (U1-xAmxO2±δ) is a promising option which would help decrease the ecological footprint of ultimate waste repository sites. In this context, this thesis is dedicated to the study of such compounds over a wide range of americium contents (7.5 at.% ≤ Am/(U+Am) ≤ 70 at.%), with an emphasis on their fabrication from single-oxide precursors and the assessment of their structural and thermodynamic stabilities, also taking self-irradiation effects into account. Results highlight the main influence of americium reduction to Am(+III), not only on the mechanisms of solid-state formation of the U1-xAmxO2±δ solid solution, but also on the stabilization of oxidized uranium cations and the formation of defects in the oxygen sublattice such as vacancies and cub-octahedral clusters. In addition, the data acquired concerning the stability of U1-xAmxO2±δ compounds (existence of a miscibility gap, vaporization behavior) were compared to calculations based on new thermodynamic modelling of the U-Am-O ternary system. Finally, α-self-irradiation-induced structural effects on U1-xAmxO2±δ compounds were analyzed using XRD, XAS and TEM, allowing the influence of americium content on the structural swelling to be studied as well as the description of the evolution of radiation-induced structural defects. (author)
9. Neptunium and americium control for international non-proliferation regime
International Nuclear Information System (INIS)
It was decided in the IAEA Board of Governors Meeting held in Sept. 1999 that Neptunium and Americium could be diverted for manufacturing nuclear weapon or explosives, so that appropriate measures should be taken for the prevention of proliferation of these materials. It is expected to take relatively long time for settling down the aligned system dealing with the above materials because the present regulatory statement was prepared on the basis of voluntary offers from the States concerned. The necessity of preventive measures is being convinced among Member States, but it would not be easy to take voluntary participation in detail because of their respective interests. It is expected that this paper could contribute to the effective response as to the international commitments as well as for protecting the domestic nuclear industry and R and D area through analysis on the IAEA's approach on Neptunium and Americium
10. Thermophysical properties of americium-containing barium plutonate
International Nuclear Information System (INIS)
Polycrystalline specimens of americium-containing barium plutonate have been prepared by mixing the appropriate amounts of (Pu0.91Am0.09)O2 and BaCO3 powders followed by reacting and sintering at 1600 K under the flowing gas atmosphere of dry-air. The sintered specimens had a single phase of orthorhombic perovskite structure and were crack-free. Elastic moduli were determined from longitudinal and shear sound velocities. Debye temperature was also determined from sound velocities and lattice parameter measurements. Thermal conductivity was calculated from measured density at room temperature, literature values of heat capacity and thermal diffusivity measured by laser flash method in vacuum. Thermal conductivity of americium-containing barium plutonate was roughly independent of temperature and registered almost the same magnitude as that of BaPuO3 and BaUO3. (author)
11. 1976 Hanford americium-exposure incident: decontamination and treatment facility
International Nuclear Information System (INIS)
An injured worker, contaminated with over 6 mCi of americium-241, required special treatment and housing for 4 months. This paper is a description of the design and management of the facility in which most of the treatment and housing occurred. The problems associated with contamination control, waste handling, supplies, and radiological concerns during the two-stage transfer of the patient from a controlled situation to his normal living environment are discussed in detail
12. Ingestion Pathway Transfer Factors for Plutonium and Americium
Energy Technology Data Exchange (ETDEWEB)
Blanchard, A.
1999-07-28
Overall transfer factors for major ingestion pathways are derived for plutonium and americium. These transfer factors relate the radionuclide concentration in a given foodstuff to deposition on the soil. Equations describing basic relationships consistent with Regulatory Guide 1.109 are followed. Updated values and coefficients from IAEA Technical Reports Series No. 364 are used when a available. Preference is given to using factors specific to the Savannah River Site.
13. Method for removal of plutonium impurity from americium oxides and fluorides
Science.gov (United States)
FitzPatrick, John R.; Dunn, Jerry G.; Avens, Larry R.
1987-01-01
Method for removal of plutonium impurity from americium oxides and fluorides. AmF.sub.4 is not further oxidized to AmF.sub.6 by the application of O.sub.2 F at room temperature, while plutonium compounds present in the americium sample are fluorinated to volatile PuF.sub.6, which can readily be separated therefrom, leaving the purified americium oxides and/or fluorides as the solid tetrafluoride.
14. Gut uptake factors for plutonium, americium and curium
International Nuclear Information System (INIS)
Data on estimates of the absorption of plutonium, americium and curium from the human gut based on measurements of uptake in other mammalian species are reviewed. It is proposed that for all adult members of the public ingesting low concentrations of plutonium in food and water, 0.05% would be an appropriate value of absorption except when the conditions of exposure are known and a lower value can be justified. For dietary intakes of americium and curium, the available data do not warrant a change from the ICRP value of 0.05%. For newborn children ingesting americium, curium and soluble forms of plutonium, a value of 1% absorption is proposed for the first 3 months of life during which the infant is maintained on a milk diet. It is proposed that a value of 0.5% should be used for the first year of life to take account of the gradual maturation of the gut. In considering the ingestion of insoluble oxides of plutonium by infants, it is proposed that absorption is taken as 0.1% for the first 3 months and 0.05% for the first year. (author)
15. Conversion of Alcohols to Bromides by Trimethylsilane and lithium Bromide in Acetone
Institute of Scientific and Technical Information of China (English)
Wei Feng; Zhang Xiao-xia; Zhang Qing; Wang Ji-yu; Chen Dai-mo
2004-01-01
Conversion of alcohols to alkyl bromides is one of the most frequently used functional group transformation reactions. Phosphorus tribromide is one of the most popular classical reagents.Triphenylphosphine has been used in combination with bromine,carbon tetrabromide,N-halo imides and other bromide compounds as a mild reagents for the preparation of alkyl bromides.More reacently, halotrimethylsilanes were found to be useful for halogenation of alcohols. George A.Olah successfully converted alcohols to bromides with chlorotrimethylsilane/lithium bromide in acetonitrile. But in our research, we found that we got no bromides but methylation products when we planed to convered our substances to bromides according to Gerge's method. We did some experiments, and we found that when the substituent group in the 2-N was donor group,we got the methylation products,but when it was acceptor group,the bromide could be got.(Scheme 1).Then we did some experiments with several other solvents, we found excitedly that when the solvent was acetone ,the bromides could be got even the substituent group was donor.(Scheme 2).When we changed the substances to normal alcohols ,such as ethyl alcohol,benzyl alcohol,isopropyl alcohol and 3,4-dimethoxy benzyl alcohol,we also got the bromides.In conclusion, we found a simple method to convert alcohols to bromides with trimethylsilane/li thium bromide in acetone,which was better than Geroge's method.
16. Airborne plutonium-239 and americium-241 concentrations measured from the 125-meter Hanford Meteorological Tower
International Nuclear Information System (INIS)
Airborne plutonium-239 and americium-241 concentrations and fluxes were measured at six heights from 1.9 to 122 m on the Hanford meteorological tower. The data show that plutonium-239 was transported on nonrespirable and small particles at all heights. Airborne americium-241 concentrations on small particles were maximum at the 91 m height
17. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.
Science.gov (United States)
2010-01-01
... 10 Energy 1 2010-01-01 2010-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a...
18. Uncertainty analysis of doses from ingestion of plutonium and americium.
Science.gov (United States)
Puncher, M; Harrison, J D
2012-02-01
Uncertainty analyses have been performed on the biokinetic model for americium currently used by the International Commission on Radiological Protection (ICRP), and the model for plutonium recently derived by Leggett, considering acute intakes by ingestion by adult members of the public. The analyses calculated distributions of doses per unit intake. Those parameters having the greatest impact on prospective doses were identified by sensitivity analysis; the most important were the fraction absorbed from the alimentary tract, f(1), and rates of uptake from blood to bone surfaces. Probability distributions were selected based on the observed distribution of plutonium and americium in human subjects where possible; the distributions for f(1) reflected uncertainty on the average value of this parameter for non-specified plutonium and americium compounds ingested by adult members of the public. The calculated distributions of effective doses for ingested (239)Pu and (241)Am were well described by log-normal distributions, with doses varying by around a factor of 3 above and below the central values; the distributions contain the current ICRP Publication 67 dose coefficients for ingestion of (239)Pu and (241)Am by adult members of the public. Uncertainty on f(1) values had the greatest impact on doses, particularly effective dose. It is concluded that: (1) more precise data on f(1) values would have a greater effect in reducing uncertainties on doses from ingested (239)Pu and (241)Am, than reducing uncertainty on other model parameter values and (2) the results support the dose coefficients (Sv Bq(-1) intake) derived by ICRP for ingestion of (239)Pu and (241)Am by adult members of the public.
19. Recovery of americium-241 from aged plutonium metal
International Nuclear Information System (INIS)
After separation and purification, both actinides were precipitated as oxalates and calcined. A large-scale process was developed using dissolution, separation, purification, precipitation, and calcination. Efforts were made to control corrosion, to avoid product contamination, to keep the volume of process and waste solutions manageable, and to denitrate solutions with formic acid. The Multipurpose Processing Facility (MPPF), designed for recovery of transplutonium isotopes, was used for the first time for the precipitation and calcination of americium. Also, for the first time,, large-scale formic acid denitration was performed in a canyon vessel at SRP
20. Effect of 241-americium on bone marrow stroma
International Nuclear Information System (INIS)
The regulation of haemopoiesis occurs via complex interactions between the stroma and the haemopoietic cells. An attempt to further clarifying the mechanisms and the exact role of the stroma in the regulation was made in a study. Results revealed that the murine bone marrow stromal cells are highly radiosensitive after injection with 241-americium and can thus be considered as a target population after internal contamination. In addition, observations are made which may be important for risk estimation for the developing animal and during pregnancy. Contamination in utero and by lactation shows persistent damage up to 1 year after contamination at an average annual dose of 5 cGy. (author)
1. Preferential decorporation of americium by pulmonary administration of DTPA dry powder after inhalation of aged PuO2 containing americium in rats
International Nuclear Information System (INIS)
After inhalation of plutonium oxides containing various percentages of americium in rats, we identified an acellular transient pulmonary compartment, the epithelial lining fluid (ELF), in which a fraction of actinide oxides dissolve prior to absorption and subsequent extrapulmonary deposit. Chelation therapy is usually considered to be poorly efficient after inhalation of actinide oxides. However, in the present study, prompt pulmonary administration of diethylenetriaminepentaacetic acid (DTPA) as a dry powder led to a decrease in actinide content in ELF together with a limitation of bone and liver deposits. Because americium is more soluble than plutonium, higher amounts of americium were found in ELF, extrapulmonary tissues and urine. Our results also demonstrated that the higher efficacy of DTPA on americium compared to plutonium in ELF induced a preferential inhibition of extrapulmonary deposit and a greater urinary excretion of americium compared to plutonium. All together, our data justify the use of an early and local DTPA treatment after inhalation of plutonium oxide aerosols in which americium can be in high proportion such as in aged compounds. (authors)
2. Kilogram-scale purification of americium by ion exchange
Energy Technology Data Exchange (ETDEWEB)
Wheelwright, E. J.
1979-01-01
Sequential anion and cation exchange processes have been used for the final purification of /sup 241/Am recovered during the reprocessing of aged plutonium metallurgical scrap. Plutonium was removed by absorption of Dowex 1, X-3.5 (30 to 50 mesh) anion exchange resin from 6.5 to 7.5 M HNO/sub 3/ feed solution. Following a water dilution to 0.75 to 1.0 M HNO/sub 3/, americium was absorbed on Dowex 50W, X-8 (50 to 100 mesh) cation exchange resion. Final purification was accomplished by elution of the absorbed band down 3 to 4 successive beds of the same resin, preloaded with Zn/sup 2 +/, with an NH/sub 4/OH buffered chelating agent. The recovery of mixed /sup 241/Am-/sup 243/Am from power reactor reprocessing waste has been demonstrated. Solvent extraction was used to recover a HNO/sub 3/ solution of mixed lanthanides and actinides from waste generated by the reprocessng of 13.5 tons of Shippingport Power Reactor blanket fuel. Sequential cation exchange band-displacement processes were then used to separate americium and curium from the lanthanides and then to separate approx. 60 g of /sup 244/Cm from 1000 g of mixed /sup 241/Am-/sup 243/Am.
3. Analytical performance of radiochemical method for americium determination in urine
International Nuclear Information System (INIS)
This paper presents an analytical method developed and adapted for separation and analysis of Plutonium (Pu) isotopes and Americium (Am) in urine samples. The proposed method will attend the demand of internal exposure monitoring program for workers involved mainly with dismantling rods and radioactive smoke detectors. In this experimental procedure four steps are involved as preparation of samples, sequential radiochemical separation, preparation of the source for electroplating and quantification by alpha spectrometry. In the first stage of radiochemical separation, plutonium is conventionally isolated employing the anion exchange technique. Americium isolation is achieved sequentially by chromatographic extraction (Tru.spec column) from the load and rinse solutions coming from the anion exchange column. The 243Am tracer is added into the sample as chemical yield monitors and to correct the results improving the precision and accuracy. The mean recovery obtained is 60%, and the detection limit for 24h urine sample is 1.0 mBq L-1 in accordance with the literature. Based in the preliminary results, the method is appropriate to be used in monitoring programme of workers with a potential risk of internal contamination. (author)
4. Development of separation techniques of americium from reprocessing solution
International Nuclear Information System (INIS)
Americium(Am) and neptunium(Np) finally transfer to the waste stream in the current PUREX reprocessing process. As an option, some methods have been developed to recover Am and Np from the waste stream to decrease long-term toxicity of the high level waste. The most stable valence state of Am is III, but TBP (tri-n-butyl phosphate) which is an extractant used in the PUREX reprocessing does not extract Am(III). Therefore, some special extractants have been developed to recover Am(III). However, they also extract rare-earth elements(REs), which necessitates the separation process for Am from REs. We have been developing a separation process which consists of valence control of Am to the VI state and its extraction with TBP. This process allows Am recovery from reprocessing solution and Am separation from REs simultaneously. Americium(III) is oxidized to Am(VI) by electrochemical oxidation and chemical oxidation using peroxodisulfate ammonium and silver nitrate. The latter was adopted here because the chemical oxidation reaction proceeds faster than the electrochemical method. Reaction mechanisms of oxidation and extraction were investigated. Based on the mechanisms, we found that extraction efficiency could be improved and waste generation could be minimized. (author)
5. Selective leaching studies of deep-sea sediments loaded with americium, neptunium and plutonium
International Nuclear Information System (INIS)
A series of selective leaching experiments were undertaken to investigate the solid phase speciation and distribution of americium, neptunium and plutonium which had been experimentally loaded onto different marine sediment types. The chemical leaches employed showed rather poor selectivity but certain trends were evident. Adsorption was not by ion exchange. Americium showed a preferential affinity for carbonate and plutonium for organic matter. Neptunium appeared to have no preferential affinities. Americium was sorbed by acetic acid residues (CaCO3 removed) and by unleached carbonate-rich sediments with equal efficiency. This indicates that it is able to diversify its solid phase affinity/distribution depending upon which solid phases are available. (author)
6. Investigation of drug interactions with pinaverium bromide.
Science.gov (United States)
Devred, C; Godeau, P; Guerot, C; Librez, P; Mougeot, G; Orsetti, A; Segrestaa, J M
1986-01-01
A series of studies was carried out at 6 centres to investigate possible drug interaction between the spasmolytic, pinaverium bromide, and cardiac glycosides, anticoagulants and hypoglycaemic agents given to patients as part of the long-term treatment of their condition. The results of clinical and laboratory investigations did not show any evidence of pinaverium bromide interfering with the action or activity of any of the drugs studied. PMID:3084176
7. Pretreatment of americium/curium solutions for vitrification
International Nuclear Information System (INIS)
Vitrification will be used to stabilize an americium/curium (Am/Cm) solution presently stored in F-Canyon for eventual transport to the heavy isotope programs at Oak Ridge National Laboratory. Prior to vitrification, an in-tank oxalate precipitation and a series of oxalic/nitric acid washes will be used to separate these elements and lanthanide fission products from the bulk of the uranium and metal impurities present in the solution. Pretreatment development experiments were performed to understand the behavior of the lanthanides and the metal impurities during the oxalate precipitation and properties of the precipitate slurry. The results of these experiments will be used to refine the target glass composition allowing optimization of the primary processing parameters and design of the solution transfer equipment
8. Plutonium and americium in sediments of Lithuanian lakes
International Nuclear Information System (INIS)
The assessment of contribution of the global and the Chernobyl NPP (Nuclear Power Plant) accident plutonium and americium to plutonium pollution in sediments of Lithuanian lakes is presented. Theoretical evaluation of activity ratios of 238Pu/239+240Pu and 241Pu/239+240Pu in the reactor of unit 4 of the Chernobyl NPP before the accident was performed by means of the ORIGEN-ARP code from the SCALE 4.4A program package. Non-uniform distribution of radionuclides in depositions on the Lithuanian territory after nuclear weapon tests and the Chernobyl NPP accident is experimentally observed by measuring the lake sediment pollution with actinides. The activity concentration of sediments polluted with plutonium ranges from 2.0 ± 0.5 Bq/kg d.w. (dry weight) in Lake Asavelis to 14 ± 2 Bq/kg d.w. in Lake Juodis. The ratio of activity concentrations of plutonium isotopes 238Pu/239+240Pu measured by α-spectrometry in the 10-cm-thick upper layer of bottom sediment varies from 0.03 in Lake Juodis to 0.3 in Lake Zuvintas. The analysis of the ratio values shows that the deposition of the Chernobyl origin plutonium is prevailing in southern and south-western regions of Lithuania. Plutonium of nuclear weapon tests origin in sediments of lakes is observed on the whole territory of Lithuania, and it is especially distinct in central Lithuania. The americium activity due to 241Pu decay after the Chernobyl NPP accident and global depositions in bottom sediments of Lithuanian lakes has been evaluated to be from 0.9 to 5.7 Bq/kg. (author)
9. Kinetic parameters of transformation of americium and plutonium physicochemical forms in podsol soils
International Nuclear Information System (INIS)
Kinetic parameters of transformation of americium and plutonium physicochemical forms have been estimated and the prognosis of fixing and remobilization of these nuclides in podsol soils have been made on that basis in the work. (authors)
10. Calibration procedures for in vivo sodium iodide spectrometry of plutonium and americium in the human lung
International Nuclear Information System (INIS)
This paper describes the calibration techniques and associated error analysis for the in vivo measurement by NaI spectrometry of heavy elements in the lung, specifically plutonium and americium. A very brief description of the instrumentation system is included
11. Relativistic density functional theory modeling of plutonium and americium higher oxide molecules
Science.gov (United States)
Zaitsevskii, Andréi; Mosyagin, Nikolai S.; Titov, Anatoly V.; Kiselev, Yuri M.
2013-07-01
The results of electronic structure modeling of plutonium and americium higher oxide molecules (actinide oxidation states VI through VIII) by two-component relativistic density functional theory are presented. Ground-state equilibrium molecular structures, main features of charge distributions, and energetics of AnO3, AnO4, An2On (An=Pu, Am), and PuAmOn, n = 6-8, are determined. In all cases, molecular geometries of americium and mixed plutonium-americium oxides are similar to those of the corresponding plutonium compounds, though chemical bonding in americium oxides is markedly weaker. Relatively high stability of the mixed heptoxide PuAmO7 is noticed; the Pu(VIII) and especially Am(VIII) oxides are expected to be unstable.
12. Distribution of uranium, americium and plutonium in the biomass of freshwater macrophytes
Energy Technology Data Exchange (ETDEWEB)
Zotina, T.A.; Kalacheva, G.S.; Bolsunovsky, A.YA. [Institute of Biophysics SB RAS, Akademgorodok, Krasnoyarsk (Russian Federation)
2010-07-01
Accumulation of uranium ({sup 238}U), americium ({sup 241}Am) and plutonium ({sup 242}Pu) and their distribution in cell compartments and biochemical components of the biomass of aquatic plants Elodea canadensis, Ceratophyllum demersum, Myrioplyllum spicatum and aquatic moss Fontinalis antipyretica have been investigated in laboratory batch experiments. Isotopes of uranium, americium and plutonium taken up from the water by Elodea canadensis apical shoots were mainly absorbed by cell walls, plasmalemma and organelles. A small portion of isotopes (about 6-13 %) could be dissolved in cytoplasm. The major portion (76-92 %) of americium was bound to cell wall cellulose-like polysaccharides of Elodea canadensis, Myriophyllum spicatum, Ceratophyllum demersum and Fontinalis antipyretica, 8-23 % of americium activity was registered in the fraction of proteins and carbohydrates, and just a small portion (< 1%) in lipid fraction. The distribution of plutonium in the biomass fraction of Elodea was similar to that of americium. Hence, americium and plutonium had the highest affinity to cellulose-like polysaccharides in Elodea biomass. Distribution of uranium in the biomass of Elodea differed essentially from that of transuranium elements: a considerable portion of uranium was recorded in the fraction of protein and carbohydrates (51 %). From our data we can assume that uranium has higher affinity to carbohydrates than proteins. (authors)
13. [The clinical pharmacological profile of pinaverium bromide].
Science.gov (United States)
Guslandi, M
1994-04-01
Pinaverium bromide is a locally acting spasmolytic agent of the digestive tract. Its mechanism of action relies upon inhibition of calcium ion entrance into smooth muscle cells (calcium-antagonist effect). In humans pinaverium facilitates gastric emptying and decreases intestinal transit time in patients with constipation. Pinaverium is very effective in improving symptoms of irritable bowel syndrome (abdominal pain, gas, diarrhea or constipation). In this respect the drug proved to be significantly superior to placebo, at least as effective as trimebutine and on the whole more active than otilonium and prifinium bromide, being always extremely well tolerated. PMID:8028745
14. Effects of pinaverium bromide on Oddi's sphincter.
Science.gov (United States)
DiSomma, C; Reboa, G; Patrone, M G; Mortola, G P; Sala, G; Ciampini, M
1986-01-01
Twelve to 15 days after cholecystectomy, endocholedochal pressure was measured in ten patients before and one hour after oral administration of 15 mg of pinaverium bromide (six patients) or placebo. The mean endocholedochal pressure was 7.1 +/- 0.25 mmHg before and 3.1 +/- 0.2 mmHg after pinaverium (P less than 0.01), and 7.0 +/- 0.2 and 6.8 +/- 1.2 mmHg in the placebo-treated patients. The results suggest that pinaverium bromide has a specific effect on the common bile duct and probably on Oddi's sphincter. PMID:3815457
15. Effect of americium-241 on luminous bacteria. Role of peroxides
Energy Technology Data Exchange (ETDEWEB)
Alexandrova, M., E-mail: maka-alexandrova@rambler.r [Siberian Federal University, Svobodny 79, 660041 Krasnoyarsk (Russian Federation); Rozhko, T. [Siberian Federal University, Svobodny 79, 660041 Krasnoyarsk (Russian Federation); Vydryakova, G. [Institute of Biophysics SB RAS, Akademgorodok 50, 660036 Krasnoyarsk (Russian Federation); Kudryasheva, N. [Siberian Federal University, Svobodny 79, 660041 Krasnoyarsk (Russian Federation); Institute of Biophysics SB RAS, Akademgorodok 50, 660036 Krasnoyarsk (Russian Federation)
2011-04-15
The effect of americium-241 ({sup 241}Am), an alpha-emitting radionuclide of high specific activity, on luminous bacteria Photobacterium phosphoreum was studied. Traces of {sup 241}Am in nutrient media (0.16-6.67 kBq/L) suppressed the growth of bacteria, but enhanced luminescence intensity and quantum yield at room temperature. Lower temperature (4 {sup o}C) increased the time of bacterial luminescence and revealed a stage of bioluminescence inhibition after 150 h of bioluminescence registration start. The role of conditions of exposure the bacterial cells to the {sup 241}Am is discussed. The effect of {sup 241}Am on luminous bacteria was attributed to peroxide compounds generated in water solutions as secondary products of radioactive decay. Increase of peroxide concentration in {sup 241}Am solutions was demonstrated; and the similarity of {sup 241}Am and hydrogen peroxide effects on bacterial luminescence was revealed. The study provides a scientific basis for elaboration of bioluminescence-based assay to monitor radiotoxicity of alpha-emitting radionuclides in aquatic solutions. - Highlights: {yields} Am-241 in water solutions (A = 0.16-6.7 kBq/L) suppresses bacterial growth.{yields} Am-241 (A = 0.16-6.7 kBq/L) stimulate bacterial luminescence. {yields} Peroxides, secondary radiolysis products, cause increase of bacterial luminescence.
16. Electrical polarization of lead bromide crystals. I
NARCIS (Netherlands)
Schoonman, A.; Macke, A.J.H.
1972-01-01
An attempt was made to measure electronic conductivity in lead bromide in equilibrium with lead, since experimental data on the cell −Pb/PbBr2/C+ in the literature are not consistent with existing theories. Combination of our results with published data for bromine-induced hole conduction in lead br
17. A comparison of the action of otilonium bromide and pinaverium bromide: study conducted under clinical control.
Science.gov (United States)
Defrance, P; Casini, A
1991-11-01
We studied 40 patients with irritable bowel syndrome (IBS) which received in a simple-blind fashion otilonium and pinaverium bromide (15 days each drug). During each 15-day period we evaluated: number of pain episodes, intensity of pain, number of bowel movements, side effects. Otilonium bromide, (OB), compared with pinaverium bromide was able to significantly (p less than 0.05) reduce the number of pain attacks, whereas no significant differences were found between the 2 groups as regards the other parameters. The occurrence of side effects was similar in the two treatment courses. We can conclude that the two types of treatment were similarly useful in IBS, although OB seems more effective than pinaverium bromide. PMID:1756286
18. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...
Science.gov (United States)
2010-01-01
... or radium-226: Requirements for license to manufacture or initially transfer. 32.57 Section 32.57... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of...
19. Separation and determination of americium in low-level alkaline waste of NPP origin
Science.gov (United States)
Todorov, B.; Djingova, R.; Nikiforova, A.
2006-01-01
The aim of this work is to develop a short and cost-saving procedure for the determination of 241Am in sludge sample of the alkaline low-level radioactive waste (LL LRAW) collected from Nuclear Power Plant “Kozloduy”. The determination of americium was a part of a complex analytical approach, where group actinide separation was achieved. An anion exchange was used for separation of americium from uranium, plutonium and iron. For the separation of americium extraction with diethylhexyl phosphoric acid (DEHPA) was studied. The final radioactive samples were prepared by micro co-precipitation with NdF3, counted by alpha and gamma spectrometry. The procedure takes 2 hours. The recovery yield of the procedure amounts to (95 ± 1.5)% and the detection limit is 53 mBq/kg 241Am (t=150 000 s). The analytical procedure was applied for actual liquid wastes and results were compared to standard procedure.
20. Isotopic and elemental composition of plutonium/americium oxides influence pulmonary and extra-pulmonary distribution after inhalation in rats
International Nuclear Information System (INIS)
The biodistribution of plutonium and americium has been studied in a rat model after inhalation of two PuO2 powders in lungs and extra-pulmonary organs from 3 d to 3 mo. The main difference between the two powders was the content of americium (approximately 46% and 4.5% of total alpha activity). The PuO2 with a higher proportion of americium shows an accelerated transfer of activity from lungs to blood as compared to PuO2 with the lower americium content, illustrated by increased urinary excretion and higher bone and liver actinide retention. The total alpha activity measured reflects mostly the americium biological behavior. The activity contained in epithelial lining fluid, recovered in the acellular phase of broncho-alveolar lavages, mainly contains americium, whereas plutonium remains trapped in macrophages. Epithelial lining fluid could represent a transitional pulmonary compartment prior to translocation of actinides to the blood and subsequent deposition in extra-pulmonary retention organs. In addition, differential behaviors of plutonium and americium are also observed between the PuO2 powders with a higher dissolution rate for both plutonium and americium being obtained for the PuO2 with the highest americium content. Our results indicate that the biological behavior of plutonium and americium after translocation into blood differ two-fold: (1) for the two actinides for the same PuO2 aerosol, and (2) for the same actinide from the two different aerosols. These results highlight the importance of considering the specific behavior of each contaminant after accidental pulmonary intake when assessing extra-pulmonary deposits from the level of activity excreted in urine or for therapeutic strategy decisions. (authors)
1. Isotopic and elemental composition of plutonium/americium oxides influence pulmonary and extra-pulmonary distribution after inhalation in rats.
Science.gov (United States)
Van der Meeren, A; Grémy, O
2010-09-01
The biodistribution of plutonium and americium has been studied in a rat model after inhalation of two PuO(2) powders in lungs and extra-pulmonary organs from 3 d to 3 mo. The main difference between the two powders was the content of americium (approximately 46% and 4.5% of total alpha activity). The PuO(2) with a higher proportion of americium shows an accelerated transfer of activity from lungs to blood as compared to PuO(2) with the lower americium content, illustrated by increased urinary excretion and higher bone and liver actinide retention. The total alpha activity measured reflects mostly the americium biological behavior. The activity contained in epithelial lining fluid, recovered in the acellular phase of broncho-alveolar lavages, mainly contains americium, whereas plutonium remains trapped in macrophages. Epithelial lining fluid could represent a transitional pulmonary compartment prior to translocation of actinides to the blood and subsequent deposition in extra-pulmonary retention organs. In addition, differential behaviors of plutonium and americium are also observed between the PuO(2) powders with a higher dissolution rate for both plutonium and americium being obtained for the PuO(2) with the highest americium content. Our results indicate that the biological behavior of plutonium and americium after translocation into blood differ two-fold: (1) for the two actinides for the same PuO(2) aerosol, and (2) for the same actinide from the two different aerosols. These results highlight the importance of considering the specific behavior of each contaminant after accidental pulmonary intake when assessing extra-pulmonary deposits from the level of activity excreted in urine or for therapeutic strategy decisions.
2. Methyl bromide residues in fumigated cocoa beans
International Nuclear Information System (INIS)
The 14C activity in unroasted [14C]-methyl bromide fumigated cocoa beans was used to study the fate and persistence of CH3Br in the stored beans. About 70% of the residues occurred in the shells. Unchanged CH3Br could not be detected, all the sorbed CH3Br having reacted with bean constituents apparently to form 14C-methylated derivatives and inorganic bromide. No 14C activity was found in the lipid fraction. Roasting decreased the bound (non-volatile) residues, with corresponding changes in the activities and amounts of free sugars, free and protein amino acids. Roasted nibs and shells showed a two-fold increase in the volatile fraction of the 14C residue. This fraction may be related to the volatile aroma compounds formed by Maillard-type reactions. (author)
3. [Research advances in methyl bromide in the ocean].
Science.gov (United States)
Du, Hui-na; Xie, Wen-xia; Cui, Yu-qian; Chen, Jian-lei; Ye, Si-yuan
2014-12-01
Methyl bromide is an important atmospheric trace gas, which plays significant roles in the global warming and atmospheric chemistry. The ocean plays important and complex roles in the global biogeochemical cycles of methyl bromide, not only the source of atmospheric methyl bromide, but also the sink. Therefore, developing the chemical research of the soluble methyl bromide in the ocean, will not only have a certain guiding significance to the atmospheric ozone layer protection, but also provide a theoretical basis for estimating methyl bromide's contribution to the global environmental change on global scale. This paper reviewed the research advances on methyl bromide in the ocean, from the aspects of the biogeochemical cycle of methyl bromide in the ocean, the analysis and determination method, the concentration distribution, the sea-to-air flux and its sources and sinks in the atmosphere. Some deficiencies in the current studies were put forward, and the directions of the future studies were prospected. PMID:25876424
4. Adsorption-desorption characteristics of plutonium and americium with sediment particles in the estuarine environment: studies using plutonium-237 and americium-241
International Nuclear Information System (INIS)
The particle formation of plutonium and americium, their adsorption onto fresh water sediments and the desorption from the sediments in sea water were studied in the Laboratory under simulated river-estuary conditions, using γ-emitting plutonium-237 and americium-241. The results of the experiments show that the particle formation of plutonium depends on its valence states, on pH and on the salinity of the medium. For river water at pH4, some 25%, 20% and 30% of the added 237Pu was in particulate form, larger than 0.45 μm, for Pu (III), Pu (IV) and Pu (VI), respectively, while 65%, 90% and 50% of the respective valence states was associated with particles at pH 8. In sea water the general pattern remains similar, although Pu (VI) is more soluble in sea water owing to higher ligand concentrations for carbonate and bicarbonate complexes. The pH-dependency of particle formation of Am (III) is more steep than that of plutonium and seems to be influenced by colloidal substances occurring in the experimental media. The adsorption-desorption characteristics of plutonium and americium with the sediment in river water as well as sea water reflect the characteristics of their particle formation, being dependent upon such properties as valence states, the pH and salinity of the medium. A sewage effluent added to the media has small but measurable effects on the adsorption-desorption processes of plutonium. (author)
5. Cesium-137 and americium-241 distribution by granulometric fractions of soil at Azgir test site grounds
International Nuclear Information System (INIS)
In measurements of radionuclide specific content in surface soil layer of contaminated territories it is important to determine in what agglomerations of soil particles there is the highest radionuclide concentration. For this purpose granulometric composition of soil at Azgir test site was studied and cesium-137 and americium-241 distribution by soil fractions was researched. (author)
6. Apparatus for fabrication of americium- beryllium neutron sources prevents capsule contamination
Science.gov (United States)
Mohr, W. C.; Van Loom, J. A.
1967-01-01
Modified gloved enclosure is used to fill a capsule with a mixture of americium and beryllium radioactive powders to seal weld the opening, and to test it for leaks. It contains a horizontal partition, vortex mixer, mounting press, welder, test vessel, and radiation shielding to prevent surface contamination.
7. Evaluation of the readsorption of plutonium and americium in dynamic fractionations of environmental solid samples
DEFF Research Database (Denmark)
Petersen, Roongrat; Hou, Xiaolin; Hansen, Elo Harald
2008-01-01
extractions. The degree of readsorption in dynamic and conventional batch extraction systems are compared and evaluated by using a double-spiking technique. A high degree of readsorption of plutonium and americium (>75%) was observed in both systems, and they also exhibited similar distribution patterns...
8. Effect of bone-status on retention and distribution of americium-241 in bones of small rodents
International Nuclear Information System (INIS)
Forced physical exercise before and after application of americium-241 resulted in only small changes in bone-structure and behaviour of the radionuclide in bone. Feeding of a low phosphorus or low calcium diet resulted in an increased excretion of americium from bone, whereby Zn-DTPA as chelating agent removed an additional fraction of the radionuclide from bone. Low calcium diet and simultaneous continuous infusion of pharmacological doses of vitamin D-hormones didn't increase the excretion of americium more than the low calcium diet alone. (orig.)
9. Europium-doped barium bromide iodide
Energy Technology Data Exchange (ETDEWEB)
Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.
2009-10-21
Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.
10. Interaction and diffusion transport of americium in soils
Energy Technology Data Exchange (ETDEWEB)
Ramirez-Guinart, Oriol; Rigol, Anna; Vidal, Miquel [Analytical Chemistry department, Faculty of Chemistry, University of Barcelona, Marti i Franques 1-11, 08028, Barcelona (Spain)
2014-07-01
The final disposal of High Level Radioactive Wastes (HLRW) is based on its long-term storage in underground facilities located in geological stable sites with a multi-barrier system, the so called Deep Geological Repositories (DGR), that will keep HLRW confined for >10.000 years. After this period of time, leachates rich in long-live radioisotopes might escape from DGR and start to transport towards the biosphere. There is still a lack of information concerning the interaction and transport in soils of some radionuclides present in HLRW, especially for radionuclides that present a high sorption, such as americium (Am). Having reliable information about the mobility of radionuclides in soils is crucial in order to develop risk assessment models and to take proper decisions in case of soil contamination. The aim of the present work was, by means of laboratory scale experiments, to study the interaction and, for first time, to evaluate the diffusion transport of {sup 241}Am in soils. The {sup 241}Am interaction in soils was assessed by applying sorption batch assays to 20 soil samples with contrasted edaphic properties which allowed us to quantify the solid-liquid distribution coefficient (K{sub d}) and desorption percentage. K{sub d} (Am) values ranged from 10{sup 3} to 10{sup 5} L kg{sup -1} and desorption percentages were always less than 2% which denoted a high capacity of the soil to incorporate the Am and a low reversibility of the sorption process. The influence of soil properties in {sup 241}Am interaction was studied by means of multiple linear and multivariate regressions. Although a single correlation between K{sub d} (Am) values and a soil property was not found, the main properties affecting {sup 241}Am interaction in soils were soil pH, carbonate and organic matter contents in the soil. Finally, additional batch assays at different controlled pH were done to study Am sorption as a function of the contact solution pH. A variation of the Am sorption
11. SKIN DOSIMETRY IN CONDITIONS OF ITS CONSTANT SURFACE CONTAMINATION WITH SOLUTIONS OF PLUTONIUM-239 AND AMERICIUM-241
Directory of Open Access Journals (Sweden)
E. B. Ershov
2012-01-01
Full Text Available The article considers, on the basis of experimental data, the issue of assessing dose burdens to the skin basal layer in conditions of its permanent contamination with solutions of plutonium-239 and americium-241 and subsequent decontamination.
12. Influence of biofilms on migration of uranium, americium and europium in the environment; Einfluss von Biofilmen auf das Migrationsverhalten von Uran, Americium und Europium in der Umwelt
Energy Technology Data Exchange (ETDEWEB)
Baumann, Nils; Zirnstein, Isabel; Arnold, Thuro
2015-07-01
The report on the influence of biofilms on migration of uranium, americium and europium in the environment deals with the contamination problems of uranium mines such as SDAG WISMUT in Saxonia and Thuringia. In mine waters microorganisms form a complex microbiological biocoenosis in spite of low pH values and high heavy metal concentrations including high uranium concentrations. The analyses used microbiological methods like confocal laser scanning microscopy and molecular-biological techniques. The interactions of microorganism with fluorescent radioactive heavy metal ions were performed with TRLFS (time resolved laser-induced fluorescence spectroscopy).
13. Liquid-liquid extraction separation and sequential determination of plutonium and americium in environmental samples by alpha-spectrometry
International Nuclear Information System (INIS)
A procedure is described by which plutonium and americium can be determined in environmental samples. The sample is leached with nitric acid and hydrogen peroxide, and the two elements are co-precipitated with ferric hydroxide and calcium oxalate. The calcium oxalate is incinerated at 4500 and the ash is dissolved in nitric acid. Plutonium is extracted with tri-n-octylamine solution in xylene from 4M nitric acid and stripped with ammonium iodide/hydrochloric acid. Americium is extracted with thenoyltrifluoroacetone solution in xylene at pH 4 together with rare-earth elements and stripped with 1M nitric acid. Americium and the rare-earth elements thus separated are sorbed on Dowex 1 x 4 resin from 1M nitric acid in 93% methanol, the rare-earth elements are eluted with 0.1M hydrochloric acid/0.5M ammonium thiocyanate/80% methanol and the americium is finally eluted with 1.5M hydrochloric acid in 86% methanol. Plutonium and americium in each fraction are electro-deposited and determined by alpha-spectrometry. Overall average recoveries are 81% for plutonium and 59% for americium. (author)
14. 77 FR 20752 - Methyl Bromide; Proposed Pesticide Tolerance
Science.gov (United States)
2012-04-06
..., which means EPA will not know your identity or contact information unless you provide it in the body of... include your name and other contact information in the body of your comment and with any disk or CD-ROM... methyl bromide. And, although methyl bromide tends to be lipid soluble, the low octanol-water...
15. Degradation of methyl bromide in anaerobic sediments
Science.gov (United States)
Oremland, R.S.; Miller, L.G.; Strohmaler, F.E.
1994-01-01
Methyl bromide (MeBr) was anaerobically degraded in saltmarsh sediments after reaction with sulfide. The product of this nucleophilic substitution reaction was methanethiol, which underwent further chemical and bacterial reactions to form dimethyl sulfide. These two gases appeared transiently during sediment incubations because they were metabolized by methanogenic and sulfate-reducing bacteria. A second, less significant reaction of MeBr was the exchange with chloride, forming methyl chloride, which was also susceptible to attack by sulfide. Incubation of 14C-labeled methyl iodide as an analogue of MeBr resulted in the formation of 14CH4 and 14CO2 and also indicated that sulfate-reducing bacteria as well as methanogens metabolized the methylated sulfur intermediates. These results suggest that exposed sediments with abundant free sulfide, such as coastal salt-marshes, may constitute a sink for atmospheric MeBr.
16. Influence of environmental factors on the gastrointestinal absorption of plutonium and americium
International Nuclear Information System (INIS)
The absorption of plutonium and americium from the gastrointestinal tract was studied, using adult hamsters and rabbits. Both actinides were administered as inorganic compounds, as organic complexes with naturally occurring chelating agents, and in a biologically incorporated form in liver tissues. The absorption of the tetravalent and hexavalent forms of plutonium were compared and the effect of protracted administration at very low concentrations was investigated. In addition, plutonium uptake from contaminated sediments and grass, collected near a nuclear-fuel reprocessing plant, was measured. The results of these studies suggest that chronic exposure of man to plutonium and americium in food and water will not lead to any substantial increase in their gastrointestinal absorption above the values currently recommended by the International Commission on Radiological Protection to define the occupational exposure of workers
17. Electrodeposition of americium on a liquid cadmium cathode from a molten salt bath
International Nuclear Information System (INIS)
A high-activity experiment involving the electrode position of americium on a liquid cadmium cathode from a LiCl-KCl eutectic with about 3 g of AmO2 was conducted in a shielded cell in the ATALANTE complex. After describing the electrolyzer and the experimental conditions, the authors discuss the preparation of the LiCl-KCl-AmCl3 solution and briefly review its electrochemical properties. It was clearly confirmed that Am(III) reduction on an inert solid cathode occurs in two steps forming Am(II) before Am(0), whereas only one reduction step was observed on liquid cadmium. The main results of this study concern americium electrode position on the liquid cadmium cathode (recovery yields, current densities, problems encountered). The solvent properties of cadmium for actinide/lanthanide separation are discussed. (authors)
18. Analysis of americium-beryllium neutron source composition using the FRAM code
Energy Technology Data Exchange (ETDEWEB)
Hypes, P. A. (Philip A.); Bracken, D. S. (David S.); Sampson, Thomas E.; Taylor, W. A. (Wayne A.)
2002-01-01
The FRAM code was originally developed to analyze high-resolution gamma spectra from plutonium items. Its capabilities have since been expanded to include analysis of uranium spectra. The flexibility of the software also enables a capable spectroscopist to use FRAM to analyze spectra in which neither plutonium nor uranium is present in significant amounts. This paper documents the use of FRAM to determine the {sup 239}Pu/{sup 241}Am, {sup 243}Am/{sup 241}Am, {sup 237}Np/{sup 241}Am, and {sup 239}Np/{sup 241}Am ratios in americium-beryllium neutron sources. The effective specific power of each neutron source was calculated from the ratios determined by FRAM in order to determine the americium mass of each of these neutron sources using calorimetric assay. We will also discuss the use of FRAM for the general case of isotopic analysis of nonplutonium, nonuranium items.
19. Experimental Insight into the Radiation Resistance of Zirconia-Based Americium Ceramics
International Nuclear Information System (INIS)
Our works shows that the americium pyrochlore 241Am2Zr2O7 undergoes a phase transition to a defect-fluorite structure along with an unusual volume contraction when subjected to internal radiation from α-emitting actinides. Disorder relaxation proceeds through the simultaneous formation of cation anti sites and oxygen Frenkel pairs. X-ray absorption spectroscopy at the Am-LII and the Zr-K edges reveals that Am-O polyhedra show an increasing disorder with increasing exposure. In contrast, the Zr-O polyhedral units remain highly ordered, while rotating along edges and corners, thereby reducing the structural strain imposed by the growing disorder around americium. We believe it is this particular property of the compound that provides the remarkable resistance to radiation (≥9.4 * 1018) α-decay events g-1 or 0.80 dpa). (authors)
20. Standard test method for quantitative determination of americium 241 in plutonium by Gamma-Ray spectrometry
CERN Document Server
American Society for Testing and Materials. Philadelphia
1994-01-01
1.1 This test method covers the quantitative determination of americium 241 by gamma-ray spectrometry in plutonium nitrate solution samples that do not contain significant amounts of radioactive fission products or other high specific activity gamma-ray emitters. 1.2 This test method can be used to determine the americium 241 in samples of plutonium metal, oxide and other solid forms, when the solid is appropriately sampled and dissolved. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1. Calcium and zinc DTPA administration for internal contamination with plutonium-238 and americium-241.
Science.gov (United States)
Kazzi, Ziad N; Heyl, Alexander; Ruprecht, Johann
2012-08-01
The accidental or intentional release of plutonium or americium can cause acute and long term adverse health effects if they enter the human body by ingestion, inhalation, or injection. These effects can be prevented by rapid removal of these radionuclides by chelators such as calcium or zinc diethylenetriaminepentaacetate (calcium or zinc DTPA). These compounds have been shown to be efficacious in enhancing the elimination of members of the actinide family particularly plutonium and americium when administered intravenously or by nebulizer. The efficacy and adverse effects profile depend on several factors that include the route of internalization of the actinide, the type, and route time of administration of the chelator, and whether the calcium or zinc salt of DTPA is used. Current and future research efforts should be directed at overcoming limitations associated with the use of these complex drugs by using innovative methods that can enhance their structural and therapeutic properties.
2. Kinetic spectrophotometric determination of bromide in clidinium-c drug
Institute of Scientific and Technical Information of China (English)
Ali Sheibani; M. Reza Shishehbore; Zahra Tavakolian Ardakani
2011-01-01
A simple, rapid and sensitive method has been described for the determination of the trace amounts of bromide. The method is based on the catalytic effect of bromide ion on the oxidation of methylene blue by bromate in sulfuric acid media. The reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of methylene blue at 665 nm. Bromide was determined in the range of 0.05-1.90 μg/mL with the detection limit of 0.03 μg/mL. The relative standard deviations of five replicate determinations of 0.20 and 10.0 μg/mL of bromide were 2.4% and 1.8%, respectively. The influence of potential interfering ions and substances was studied. The method is applied to the analysis of bromide in clidinium-c tablet as a real sample.
3. Final Radiological Assessment of External Exposure for CLEAR-Line Americium Recovery Operations
Energy Technology Data Exchange (ETDEWEB)
Davis, Adam C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Belooussova, Olga N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hetrick, Lucas Duane [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-11-12
Los Alamos National Laboratory is currently planning to implement an americium recovery program. The americium, ordinarily isotopically pure 241Am, would be extracted from existing Pu materials, converted to an oxide and shipped to support fabrication of americium oxide-beryllium neutron sources. These operations would occur in the currently proposed Chloride Extraction and Actinide Recovery (CLEAR) line of glove boxes. This glove box line would be collocated with the currently-operational Experimental Chloride Extraction Line (EXCEL). The focus of this document is to provide an in-depth assessment of the currently planned radiation protection measures and to determine whether or not further design work is required to satisfy design-goal and ALARA requirements. Further, this document presents a history of americium recovery operations in the Department of Energy and high-level descriptions of the CLEAR line operations to provide a basis of comparison. Under the working assumptions adopted by this study, it was found that the evaluated design appears to mitigate doses to a level that satisfies the ALARA-in-design requirements of 10 CFR 835 as implemented by the Los Alamos National Laboratory procedure P121. The analyses indicate that extremity doses would also meet design requirements. Dose-rate calculations were performed using the radiation transport code MCNP5 and doses were estimated using a time-motion study developed in consort with the subject matter expert. A copy of this report and all supporting documentation are located on the Radiological Engineering server at Y:\\Rad Engineering\\2013 PROJECTS\\TA-55 Clear Line.
4. Bidentate organophosphorus extraction of americium and plutonium from Hanford Plutonium Reclamation Facility waste
Energy Technology Data Exchange (ETDEWEB)
Schulz, W.W.
1974-09-01
Applicability of bidentate organiphosphorus reagents to recovery of americium and plutonium from Hanford's Plutonium Reclamation Facility acid (approx. 2M HNO/sub 3/) waste stream (CAW solution) was studied. A solvent extraction process which employs a 30% DHDECMP (dihexyl-N, N-diethylcarbamylmethylene phosphonate)-CCl/sub 4/ extractant was devised and successfully tested in mixer-settler runs with actual CAW solution. Substitution of DHDECMP for DBBP eliminates the need to perform careful neutralization of unbuffered CAW soluton and increases overall americium recovery from the present 60 to 80% level to greater than or equal to 90%. Disadvantages to such substitution include the high cost (approx. \$50/liter) of DHDECMP and the need to purify it (by acid (6M HCl) hydrolysis and alkaline washing) from small amounts of an unidentified impurity which prevents stripping of americium with dilute HNO/sub 3/. Distribution data obtained in this study confirm Siddall's earlier contention that bidentate organophosphorus regents can be used to remove actinides from concentrated high-level Purex process acid waste; a conceptual flowsheet for such an extraction process is given.
5. Chloride, bromide and iodide scintillators with europium
Energy Technology Data Exchange (ETDEWEB)
Zhuravleva, Mariya; Yang, Kan
2016-09-27
A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.
Yubo Jiang; Chunxiang Kuang
2009-11-01
Highly functionalized ()-2-arylvinyl bromides were prepared in high yields through a new convenient access by acylation of ()-4-(2-bromovinyl)phenol with fatty and aromatic acids at room temperature using dicyclohexyl carbodiimide (DCC) and dimethylaminopyridine (DMAP).
7. Bromide space, total body water, and sick cell syndrome
Energy Technology Data Exchange (ETDEWEB)
Schober, O.; Hundeshagen, H.; Lehr, L.
1982-01-01
Displacements of the bromide space (Br-82-C, as a marker for the extracellular fluid compartment) are caused by an enhanced anatomical space and/or increased permeability of cells to bromide. The ratio Br-82-C: total body water (TBW) was evaluated to be 0.83 +- 0.17 in critically ill patients (n = 38) compared with the normal value of 0.46 +- 0.04 (n = 10). Because of normal TBW in critically ill patients (TBW = 505 +- 68 ml/kg), an increased bromide penetration into cells seems to be responsible for the enlarged ratio Br-82-C: TBW. Taking into consideration measurements in patients with malabsorption (Br-82-C: TBW = 0.56 +- 0.13; n = 13) and carcinoma of the rectum and colon (Br-82-C: TBW = 0.66 +- 0.24; n = 18) we think that the bromide space is a good measurement of the effective extracellular water.
8. Effects of ipratropium bromide and fenoterol aerosols in pulmonary emphysema.
OpenAIRE
Hughes, J A; Tobin, M. J.; Bellamy, D; Hutchison, D. C.
1982-01-01
In patients with radiological evidence of pulmonary emphysema the bronchodilator drugs fenoterol and ipratropium bromide produced a considerable increase in vital capacity and reduction in residual volume. The response to fenoterol was virtually complete 15 minutes after administration, but after ipratropium bromide vital capacity was still increasing at 60 minutes. The change in vital capacity was slightly greater with a combination of the two drugs than with either used alone. Changes in FE...
9. Quantum Chemistry Study on Dissociation of Oxalyl Bromide
Institute of Scientific and Technical Information of China (English)
2005-01-01
The multi-bond dissociation dynamics of oxalyl bromide ((BrCO)2) has been investigated by DFT and CIS calculations. Upon the results, conclusion could be drawn that dissociation of C-Br bond of oxalyl bromide at the ground state (S0) is of barrierless. After the absorption of a photon, (BrCO)2 is excited to the first excited state and one of its C-Br bonds is broken to yield dissociate.
10. Americium(3) coordination chemistry: An unexplored diversity of structure and bonding
Energy Technology Data Exchange (ETDEWEB)
Fedosseev, A.M.; Grigoriev, M.S.; Budantseva, N.A. [A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Moscow (Russian Federation); Guillaumont, D.; Den Auwer, Ch.; Moisy, Ph. [CEA Marcoule, Nuclear Energy Division, RadioChemistry and Processes Department, 30 (France); Le Naour, C.; Simoni, E. [CNRS, University Paris-11 Orsay, IPN, 91 - Orsay (France)
2010-06-15
The comparison of the physicochemical behavior of the actinides with that of the lanthanides can be justified by the analogy of their electronic structure, as each of the series is made up of elements corresponding to the filling of a given (n)f atomic shell. However relatively few points of comparison are available, given the lack of available structure for trans-plutonium(III) elements and the additional difficulty of stabilizing coordination complexes of uranium(III) to plutonium(III). This contribution is a focal point of trans-plutonium(III) chemistry and, more specifically, of some americium compounds that have been recently synthesized, all related with hard acid oxygen donor ligands that may be involved in the reprocessing chain of nuclear fuel. After a brief review of the solid hydrates and aquo species for the lanthanide and actinide families, we discuss two types of ligands that have in common three carboxylic groups, namely the amino-tri-acetic acid and the citric acid anions. The additional roles of the nitrogen atom for the first one and of the hydroxy function for the second one are discussed. Accordingly, five new complexes with either americium or lanthanides elements are described: [Co(NH{sub 3}){sub 6}][M(NTA){sub 2}(H{sub 2}O)].8H{sub 2}O with M Nd, Yb and Am, and [Co(NH{sub 3}){sub 6}]{sub 2}K[M{sub 3}(Cit){sub 4}(H{sub 2}O){sub 3}].18H{sub 2}O with Nd and Am cations. In all cases the americium complexes are isostructural with their lanthanide equivalents. (authors)
11. Americium(3) coordination chemistry: An unexplored diversity of structure and bonding
International Nuclear Information System (INIS)
The comparison of the physicochemical behavior of the actinides with that of the lanthanides can be justified by the analogy of their electronic structure, as each of the series is made up of elements corresponding to the filling of a given (n)f atomic shell. However relatively few points of comparison are available, given the lack of available structure for trans-plutonium(III) elements and the additional difficulty of stabilizing coordination complexes of uranium(III) to plutonium(III). This contribution is a focal point of trans-plutonium(III) chemistry and, more specifically, of some americium compounds that have been recently synthesized, all related with hard acid oxygen donor ligands that may be involved in the reprocessing chain of nuclear fuel. After a brief review of the solid hydrates and aquo species for the lanthanide and actinide families, we discuss two types of ligands that have in common three carboxylic groups, namely the amino-tri-acetic acid and the citric acid anions. The additional roles of the nitrogen atom for the first one and of the hydroxy function for the second one are discussed. Accordingly, five new complexes with either americium or lanthanides elements are described: [Co(NH3)6][M(NTA)2(H2O)].8H2O with M Nd, Yb and Am, and [Co(NH3)6]2K[M3(Cit)4(H2O)3].18H2O with Nd and Am cations. In all cases the americium complexes are isostructural with their lanthanide equivalents. (authors)
12. MARIOS: Irradiation of UO{sub 2} containing 15% americium at well defined temperature
Energy Technology Data Exchange (ETDEWEB)
D' Agata, E., E-mail: elio.dagata@ec.europa.eu [European Commission, Joint Research Centre, Institute for Energy - P.O. Box 2, 1755 ZG Petten (Netherlands); Hania, P.R. [Nuclear Research and Consultancy Group, P.O. Box 25, 1755 ZG Petten (Netherlands); Bejaoui, S. [Commissariat a l' Energie Atomique, DEC CEA-Cadarache, 13108 St. Paul lez Durance Cedex (France); Sciolla, C.; Wyatt, T.; Hannink, M.H.C. [Nuclear Research and Consultancy Group, P.O. Box 25, 1755 ZG Petten (Netherlands); Herlet, N.; Jankowiak, A. [Commissariat a l' Energie Atomique DTEC CEA Marcoule, 30207 Bagnols sur Ceze Cedex (France); Klaassen, F.C. [Nuclear Research and Consultancy Group, P.O. Box 25, 1755 ZG Petten (Netherlands); Bonnerot, J.-M. [Commissariat a l' Energie Atomique, DEC CEA-Cadarache, 13108 St. Paul lez Durance Cedex (France)
2012-01-15
Highlights: Black-Right-Pointing-Pointer MARIOS is designed to check the behaviour of Minor Actinide Blanket Module concept. Black-Right-Pointing-Pointer Main requirement of the experiment is an accurate control of the temperature. Black-Right-Pointing-Pointer The swelling and the helium release will be the main output of the experiment. Black-Right-Pointing-Pointer A complementary experiment (DIAMINO), will be performed in the next future. - Abstract: Americium is a strong contributor to the long term radiotoxicity of high activity nuclear waste. Transmutation by irradiation in nuclear reactors of long-lived nuclides like {sup 241}Am is, therefore, an option for the reduction of radiotoxicity and residual power packages as well as the repository area. The MARIOS irradiation experiment is the latest of a series of experiments on americium transmutation (e.g. EFTTRA-T4, EFTTRA-T4bis, HELIOS). MARIOS experiment is carried out in the framework of the 4-year project FAIRFUELS of the EURATOM 7th Framework Programme (FP7). During the past years of experimental work in the field of transmutation and tests of innovative nuclear fuel containing americium, the release or trapping of helium as well as swelling has shown to be the key issue for the design of such kinds of target. Therefore, the main objective of the MARIOS experiment is to study the in-pile behaviour of UO{sub 2} containing minor actinides (MAs) in order to gain knowledge on the role of the microstructure and of the temperature on the gas release and on fuel swelling. The MARIOS experiment will be conducted in the HFR (high flux reactor) in Petten (The Netherlands) and will start in the beginning of 2011. It has been planned that the experiment will last 11 cycles, corresponding to 11 months. This paper covers the description of the objective of the experiment, as well as a general description of the design of the experiment.
13. Speciation of americium in seawater and accumulation in the marine sponge Aplysina cavernicola.
Science.gov (United States)
Maloubier, Melody; Michel, Hervé; Solari, Pier Lorenzo; Moisy, Philippe; Tribalat, Marie-Aude; Oberhaensli, François R; Dechraoui Bottein, Marie Yasmine; Thomas, Olivier P; Monfort, Marguerite; Moulin, Christophe; Den Auwer, Christophe
2015-12-21
The fate of radionuclides in the environment is a cause of great concern for modern society, seen especially in 2011 after the Fukushima accident. Among the environmental compartments, seawater covers most of the earth's surface and may be directly or indirectly impacted. The interaction between radionuclides and the marine compartment is therefore essential for better understanding the transfer mechanisms from the hydrosphere to the biosphere. This information allows for the evaluation of the impact on humans via our interaction with the biotope that has been largely undocumented up to now. In this report, we attempt to make a link between the speciation of heavy elements in natural seawater and their uptake by a model marine organism. More specifically, because the interaction of actinides with marine invertebrates has been poorly studied, the accumulation in a representative member of the Mediterranean coralligenous habitat, the sponge Aplysina cavernicola, was investigated and its uptake curve exposed to a radiotracer (241)Am was estimated using a high-purity Ge gamma spectrometer. But in order to go beyond the phenomenological accumulation rate, the speciation of americium(III) in seawater must be assessed. The speciation of (241)Am (and natural europium as its chemically stable surrogate) in seawater was determined using a combination of different techniques: Time-Resolved Laser-Induced Fluorescence (TRLIF), Extended X-ray Absorption Fine Structure (EXAFS) at the LIII edge, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and Scanning Electron Microscopy (SEM) and the resulting data were compared with the speciation modeling. In seawater, the americium(III) complex (as well as the corresponding europium complex, although with conformational differences) was identified as a ternary sodium biscarbonato complex, whose formula can be tentatively written as NaAm(CO3)2·nH2O. It is therefore this chemical form of americium that is
14. Speciation of americium in seawater and accumulation in the marine sponge Aplysina cavernicola.
Science.gov (United States)
Maloubier, Melody; Michel, Hervé; Solari, Pier Lorenzo; Moisy, Philippe; Tribalat, Marie-Aude; Oberhaensli, François R; Dechraoui Bottein, Marie Yasmine; Thomas, Olivier P; Monfort, Marguerite; Moulin, Christophe; Den Auwer, Christophe
2015-12-21
The fate of radionuclides in the environment is a cause of great concern for modern society, seen especially in 2011 after the Fukushima accident. Among the environmental compartments, seawater covers most of the earth's surface and may be directly or indirectly impacted. The interaction between radionuclides and the marine compartment is therefore essential for better understanding the transfer mechanisms from the hydrosphere to the biosphere. This information allows for the evaluation of the impact on humans via our interaction with the biotope that has been largely undocumented up to now. In this report, we attempt to make a link between the speciation of heavy elements in natural seawater and their uptake by a model marine organism. More specifically, because the interaction of actinides with marine invertebrates has been poorly studied, the accumulation in a representative member of the Mediterranean coralligenous habitat, the sponge Aplysina cavernicola, was investigated and its uptake curve exposed to a radiotracer (241)Am was estimated using a high-purity Ge gamma spectrometer. But in order to go beyond the phenomenological accumulation rate, the speciation of americium(III) in seawater must be assessed. The speciation of (241)Am (and natural europium as its chemically stable surrogate) in seawater was determined using a combination of different techniques: Time-Resolved Laser-Induced Fluorescence (TRLIF), Extended X-ray Absorption Fine Structure (EXAFS) at the LIII edge, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and Scanning Electron Microscopy (SEM) and the resulting data were compared with the speciation modeling. In seawater, the americium(III) complex (as well as the corresponding europium complex, although with conformational differences) was identified as a ternary sodium biscarbonato complex, whose formula can be tentatively written as NaAm(CO3)2·nH2O. It is therefore this chemical form of americium that is
15. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide
International Nuclear Information System (INIS)
Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O2 lattice in an irradiated (60 MW d kg−1) MOX sample was performed employing micro-X-ray fluorescence (µ-XRF) and micro-X-ray absorption fine structure (µ-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (∼0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am3+ species within an [AmO8]13− coordination environment (e.g. >90%) and no (III XAFS spectra recorded for the irradiated MOX sub-sample in the rim zone for a 300 μm×300 μm beam size area investigated over six scans of 4 h. The records remain constant during multi-scan. The analysis of the XAFS signal shows that Am is found as trivalent in the UO2 matrix. This analytical work shall open the door of very challenging analysis (speciation of fission product and actinides) in irradiated nuclear fuels. - Highlights: • Americium was characterized by microX-ray absorption spectroscopy in irradiated MOX fuel. • The americium redox state as determined from XAS data of irradiated fuel material was Am(III). • In the sample, the Am3+ face an AmO813− coordination environment in the (Pu,U)O2 matrix. • The americium dioxide is reduced by the uranium dioxide matrix
16. Fabrication of uranium–americium mixed oxide pellet from microsphere precursors: Application of CRMP process
Energy Technology Data Exchange (ETDEWEB)
Remy, E. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Picart, S., E-mail: sebastien.picart@cea.fr [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Delahaye, T. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Jobelin, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Lebreton, F.; Horlait, D. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Bisel, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Blanchart, P. [Heterogeneous Materials Research Group, Centre Européen de la Céramique, F-87068 Limoges (France); Ayral, A. [Institut Européen des Membranes, CNRS-ENSCM-UM2, CC47, University Montpellier 2, F-34095 Montpellier cedex 5 (France)
2014-10-15
Highlights: • Dust free process for (U,Am)O{sub 2} transmutation target fabrication. • Synthesis of U{sub 0.9}Am{sub 0.1}O{sub 2} mixed oxide microspheres from ion exchange resin. • Fabrication of dense U{sub 0.9}Am{sub 0.1}O{sub 2} pellet with 95% TD from mixed oxide microspheres. - Abstract: Mixed uranium–americium oxides are one of the materials envisaged for Americium Bearing Blankets dedicated to transmutation in fast neutron reactors. Recently, several processes have been developed in order to validate fabrication flowchart in terms of material specifications such as density and homogeneity but also to suggest simplifications for lowering industrial costs and hazards linked to dust generation of highly contaminating and irradiating compounds. This study deals with the application of an innovative route using mixed oxide microspheres obtained from metal loaded resin bead calcination, called Calcined Resin Microsphere Pelletization (CRMP). The synthesis of mixed oxide microsphere precursor of U{sub 0.9}Am{sub 0.1}O{sub 2±δ} is described as well as its characterisation. The use of this free-flowing precursor allows the pressing and sintering of one pellet of U{sub 0.9}Am{sub 0.1}O{sub 2±δ}. The ceramic obtained was characterised and results showed that its microstructure is dense and homogeneous and its density attains 95% of the theoretical density. This study validates the scientific feasibility of the CRMP process applied to the fabrication of uranium and americium-containing materials.
17. Influence of biofilms on migration of uranium, americium and europium in the environment
International Nuclear Information System (INIS)
The report on the influence of biofilms on migration of uranium, americium and europium in the environment deals with the contamination problems of uranium mines such as SDAG WISMUT in Saxonia and Thuringia. In mine waters microorganisms form a complex microbiological biocoenosis in spite of low pH values and high heavy metal concentrations including high uranium concentrations. The analyses used microbiological methods like confocal laser scanning microscopy and molecular-biological techniques. The interactions of microorganism with fluorescent radioactive heavy metal ions were performed with TRLFS (time resolved laser-induced fluorescence spectroscopy).
18. Plutonium and americium in arctic waters, the North Sea and Scottish and Irish coastal zones
DEFF Research Database (Denmark)
1986-01-01
Plutonium and americium have been measured in surface waters of the Greenland and Barents Seas and in the northern North Sea from 1980 through 1984. Measurements in water and biota, Fucus, Mytilus and Patella, were carried out in North-English and Scottish waters in 1982 and Fucus samples were...... plutonium from the latter to Spitsbergen waters. Fallout plutonium in Arctic waters has a residence time of the order of several years, while for Pu from Sellafield we estimate mean residence times of 11–15 months in Scottish waters and, tentatively, 1·5-3 y during transport from the North Channel (north...
19. Comparison of acid leachate and fusion methods to determine plutonium and americium in environmental samples
International Nuclear Information System (INIS)
The Analytical Chemistry Laboratory at Argonne National Laboratory performs radiochemical analyses for a wide variety of sites within the Department of Energy complex. Since the chemical history of the samples may vary drastically from site to site, the effectiveness of any analytical technique may also vary. This study compares a potassium fluoride-pyrosulfate fusion technique with an acid leachate method. Both normal and high-fired soils and vegetation samples were analyzed for both americium and plutonium. Results show both methods work well, except for plutonium in high-fired soils. Here the fusion method provides higher accuracy
20. Purification of used scintillation liquids containing the alpha emitters americium and plutonium
International Nuclear Information System (INIS)
In Sweden, alpha radioactive waste liquids with an activity over some kBq per waste container cannot be sent for final storage. Therefore, in this work, a method for a purification of alpha active scintillation cocktails was developed. Until today (March, 2013) more than 20 L of scintillation liquids have successfully been purified from americium and plutonium. The products of the process are a solid fraction that can be sent to final storage and a practically non-radioactive liquid fraction that can be sent to municipal incineration. (author)
1. Assessment of Ethidium bromide and Ethidium monoazide bromide removal from aqueous matrices by adsorption on cupric oxide nanoparticles.
Science.gov (United States)
Fakhri, Ali
2014-06-01
The present study was undertaken to develop an effective adsorbent and to study the adsorption of Ethidium bromide and Ethidium monoazide bromide from aqueous solution using the CuO nanoparticles. The characteristics of CuO nanoparticles were determined and found to have a surface area 89.59m(2)/g. Operational parameters such as pH, contact time and adsorbent concentration, initial concentration and temperature were also studied. The amount of removal increases with the increase in pH from one to seven and reaches the maximum when the pH is nine. Adsorption data fitted well with the Langmuir, Freundlich and Florry-Huggins models. The results show that the best fit was achieved with the Langmuir isotherm equation with maximum adsorption capacities of 0.868 and 0.662mg/g for Ethidium bromide and Ethidium monoazide bromide, respectively. The adsorption process was found to follow pseudo-second-order kinetics. The calculated thermodynamic parameters, namely ΔG, ΔH and ΔS showed that adsorption of Ethidium bromide and Ethidium monoazide bromide was spontaneous and endothermic under examined conditions. PMID:24630576
2. Study of the extraction and the purification of americium and trivalent actinides contained in effluents with supported liquid membranes
International Nuclear Information System (INIS)
The supported liquid membrane technique is studied and developed for americium recovery from uranium or plutonium matrices and decontamination of liquid radioactive wastes. First tests on uranium-nickel solutions with a flat membrane showed the easiness of the operation and the efficiency of the process. Acid-resistant (10 N), interchangeable elements with hollow fibers, are developed and also a computerized automatic device. The different tests on americium solutions demonstrate the feasibility and the reliability of the system. Influence of various parameters on transfer kinetics is investigated
3. Contribution to the prediction of americium, plutonium and neptunium behaviour in the geosphere: chemical data
International Nuclear Information System (INIS)
An exhaustive bibliographic review on hydrolysis of americium gives the stability constants, at zero ionic strength. No evidence of Am(OH)4- formation was found by solubility studies up to pH 2 (CO3)3 characterised by its X-ray diffraction pattern is studied at a high ionic strength. All the published results on Am in carbonate media are reinterpreted using these stability constants (Am-OH-CO3 complexes are not needed). No evidence of Am(CO3)45- formation was found by spectrophotometry up to 3M. Literature results are used to determine the formal redox potentials at pH = 9.4 and to calculate the formation constants, at zero ionic strength. The formation of complexes between americium and humic materials (purified fulvic and humic acids) has been studied by a spectrophotometric technique. The results are interpreted by the formation of a 1:1 complexe. Solubility of the solid PuO2(CO3) is measured in bicarbonate media at high ionic strength, to obtain the solubility product and formation constants of the PuO2(CO3)i2-2i complexes
4. Electrophysiological study of intravenous pinaverium bromide in cardiology.
Science.gov (United States)
Guerot, C; Khemache, A; Sebbah, J; Noel, B
1988-01-01
Pinaverium bromide is a musculotropic spasmolytic agent which acts by inhibiting transmembrane calcium movements, an effect similar to that of verapamil. Because of this, an investigation was carried out to see if it had any electrophysiological effects in patients with various cardiac disorders. In an open study, 10 patients received 2 mg pinaverium bromide intravenously. In a double-blind study, 10 patients received 4 mg pinaverium bromide intravenously and 10 patients placebo. Patients included those with either normal or pathological basal conduction, such as bundle-branch block and 1st degree atrioventricular block. Measurements were made of electrophysiological parameters before and 10 minutes after injection. The results showed that neither of the two doses of pinaverium bromide had any effect on atrial excitability, sino-atrial conduction, node and trunk atrioventricular conduction or on intraventricular conduction. No significant difference was seen in comparison with placebo. Pinaverium bromide had no anti-arrhythmic properties in these studies. Local, cardiac and general clinical tolerability was good in all patients. PMID:3219882
5. The distribution of plutonium-239 and americium-241 in the Syrian hamster following its intravenous administration as citrate
International Nuclear Information System (INIS)
Actinide distribution in various tissues and the skeleton of hamsters by liquid scintillation counting or isotope dilution. For plutonium 57% of activity was concentrated in the skeleton and more than 90% in the liver and skeleton after seven days. For americium the liver retained more than 50% of total activity and 25% was excreted in urine within seven days. (U.K.)
6. EURADOS intercomparison on measurements and Monte Carlo modelling for the assessment of Americium in a USTUR leg phantom
International Nuclear Information System (INIS)
A collaboration of the EURADOS working group on 'Internal Dosimetry' and the United States Transuranium and Uranium Registries (USTUR) has taken place to carry out an intercomparison on measurements and Monte Carlo modelling determining americium deposited in the bone of a USTUR leg phantom. Preliminary results and conclusions of this intercomparison exercise are presented here. (authors)
7. Anomalous aryl strengthening of americium and europium complexes during extraction by alkylenediphosphine dioxides from perchloric acid media
International Nuclear Information System (INIS)
Extraction of americium and europium from perchlorate environments by solutions of three types of methylenediphosphine dioxides, namely (C6H5)P(O)(CH2)sub(n)(O)P(C6H5)2, (C6H5)2P(O)CH2(O)P(C8H17)2 and (C8H17)2P(O)(CH2)sub(n)(O)P(C8H17)2 has been studied (n is 1 or 2 ) The diluents used have been dichlorethane and chloroform. In perchlorate environments the distribuiton coefficients of americium and europium have proved to be by about 3 orders of magnitude higher than in nitric acid environments, i.e. in perchlorate media the complexes are far more stable. Separation coefficients of americium and REE in perchloric acid soutions are much higher than in nitrate environments. The average value of Am/Eu separation coeffecient at 1-5 M acidity was about 6 (with dichlorethane as diluent) or about 7 (with chloroform as diluent). The complexes essentially exist as trisolvated. Americium complexes display anomalous stability increase upon being diluted: by about 2 orders of magnitude with dichlorethane and by up to 3 orders of magnitude with chloroform used as diluent
8. Investigations of neutron characteristics for salt blanket models; integral fission cross section measurements of neptunium, plutonium, americium and curium isotopes
International Nuclear Information System (INIS)
Neutron characteristics of salt blanket micromodels containing eutectic mixtures of sodium, zirconium, and uranium fluorides were measured on FKBN-2M, BIGR and MAKET facilities. The effective fission cross sections of neptunium, plutonium, americium, and curium isotopes were measured on the neutron spectra formed by micromodels. (author)
9. IR, Raman and SERS spectra of propantheline bromide.
Science.gov (United States)
Baraldi, C; Freguglia, G; Tinti, A; Sparta, M; Alexandrova, A N; Gamberini, M C
2013-02-15
The two known propantheline bromide polymorphs (form I and form II) were studied and characterized by a multianalytical approach. In the present work, the identification of propantheline bromide polymorphic forms through vibrational IR spectroscopies are presented and for the first time Raman microscopy and hot stage Raman microscopy (HSRM) studies are reported. Finally, quantum mechanical calculations were performed. For assisting the assignment of the experimental picks, the two IR spectra of the most and least stable representatives of a set of 56 conformers are calculated and studied. DSC thermograms data, are also reported. The surface enhanced Raman scattering (SERS) spectrum was also recorded in a silver colloid; it could be inferred that propantheline bromide is adsorbed on silver colloid through the oxygen atom with the molecular plane perpendicular to the metal surface.
10. Glycosylation with Disarmed Glycosyl Bromides Promoted by Iodonium Ions
DEFF Research Database (Denmark)
2016-01-01
Iodonium ions have been developed for activating glycosyl bromides in the coupling to glycosyl acceptors. The iodonium ions are generated from N-iodosuccinimide and a protic acid such as camphorsulfonic acid or triflic acid, where the latter gives the most reactive promoter system. The couplings...... occur with the release of iodine monobromide, and the best results are obtained with benzoylated glycosyl donors and acceptors. In this way, disarmed glycosyl bromides can serve as glycosyl donors without the use of heavy-metal salts....
11. Action of pinaverium bromide on calmodulin-regulated functions.
Science.gov (United States)
Wuytack, F; De Schutter, G; Casteels, R
1985-08-01
Pinaverium bromide at concentrations below 10(-5) M did not inhibit calmodulin-dependent enzymes such as phosphodiesterase and the Ca transport ATPase of the plasma membrane. At higher concentrations the compound interacted with the stimulation of those enzymes by calmodulin and also inhibited the calmodulin-independent activity. A similar inhibitory action was observed for the NaK ATPase. It is concluded that the inhibitory action of pinaverium bromide on smooth muscle concentration at concentrations below 10(-5) M was due to its interaction with the voltage-dependent Ca channels and not to its interference with the calmodulin-dependent activation of the contractile proteins. PMID:2995077
12. Investigation of possible interaction between pinaverium bromide and digoxin.
Science.gov (United States)
Weitzel, O; Seidel, G; Engelbert, S; Berksoy, M; Eberhardt, G; Bode, R
1983-01-01
A single-blind study was carried out in 25 patients, who were receiving maintenance therapy for congestive heart failure with digoxin, to investigate the effect on steady-state plasma digoxin levels of concomitant administration of the spasmolytic, pinaverium bromide (50 mg 3-times daily). Patients received pinaverium bromide for 12 days followed by placebo for a further 7 days. Assessment of the results in 21 patients showed no evidence of any statistically significant variations in plasma digoxin levels during either treatment period or in the clinical observations which might indicate drug interaction. PMID:6653138
13. Purification of scintillation cocktails containing the alpha emitters americium and plutonium
International Nuclear Information System (INIS)
One efficient way of measuring alpha emitters is by the usage of liquid scintillation counting (LSC). A liquid sample is placed in a vial containing a scintillation cocktail. The alpha particles excite electrons in the surrounding liquid, and when they are de-excited photons are emitted. The photons are detected and the activity can be quantified. LSC has a high efficiency for alpha radiation and is therefore a fast and easy way for measuring alpha emitting samples. One drawback is that it does not differentiate very well between alpha energies; measurements of for example curium and plutonium simultaneously are impossible and demand other techniques. Another drawback is the production of a liquid alpha active waste. In Sweden alpha radioactive waste liquids with an activity over some kBq per waste container cannot be sent for final storage. If, however, the activity of the liquids could be reduced by precipitation of the actinides, it would be possible to send away the liquid samples to municipal incineration. In this work a method for a purification of alpha active scintillation cocktails was developed. The method was first tried on a lab scale, and then scaled up. Until today (March, 2013) more than 20 liters of scintillation liquids have successfully been purified from americium and plutonium at Chalmers University of Technology in Sweden. The four scintillation cocktails used were Emulsifier Safe®, Hionic-Fluor®, Ultima Gold AB® and Ultima Gold XR®. The scintillation cocktails could all be purified from americium with higher yield than 95%. The yield was kept when the liquids were mixed. Also plutonium could be precipitated with a yield over 95% in all cocktails except in Hionic-Fluor® (>55%). However, that liquid in particular could be purified (>95%) by mixing it with the three other cocktails. Up-scaling was performed to a batch size of 6-8 L of scintillation cocktail. In neither the americium nor the plutonium system, adverse effects of increasing the
14. A thermodynamic study of actinide oxide targets/fuels for americium transmutation
International Nuclear Information System (INIS)
A thermodynamic study was performed on the systems Am-O, AmOx-MgO, AmOx-MgAl2O4, Pu-Mg-O and U-Mg-O. Both experimental work (X-ray analyses, oxygen potential measurements etc.) and calculations on the phase diagrams involved were made. The reaction between americium oxide and spinel is expected to form the compound AmAlO3. Isothermal sections have been calculated for AmOx-(MgO, Al2O3), Pu-Mg-O and U-Mg-O at 2000 K using the software package ''Thermo-Calc''. Thermodynamic equilibrium data were used to predict the behaviour of actinide oxides in a reactor. The implication of the results for the technological application is discussed, with emphasis on the effects of the high oxygen potential of AmO2 as compared to the conventional fuel, i.e. UO2. (author)
15. The uptake of plutonium-239, 240, americium-241, strontium-90 into plants
International Nuclear Information System (INIS)
This report describes the results of measurements on the uptake of plutonium, americium, strontium-90 and caesium-137 into peas, beet, oats, sweet corn, tomatoes and vegetable marrow grown in tubs containing radioactively-contaminated silts. The silts had been taken from an area of West Cumbria commonly referred to as the Ravenglass estuary. The experiments are categorised as being carried out under non-standard conditions because of the manner in which the radioactivity came to be incorporated into the growth medium. The growth medium was representative of conditions which could arise when the estuarine silt moves inland under the influence of wind and tide and mixes with the adjacent farm land. The silt had been contaminated by radioactive effluents from the nuclear fuels reprocessing plant at Sellafield and this contamination had been brought about by natural means. (Auth.)
16. Complex formation of trivalent americium with salicylic acid at very low concentrations
International Nuclear Information System (INIS)
For the first time, the complexation of americium(III) with salicylic acid was studied at trace metal concentrations using a 2.0 m Long Path Flow Cell for UV-vis spectroscopy. The detection limit of Am(III) in aqueous solution at pH 3.0 was found to be 5 x 10-9 M. Two Am(III)-salicylate complexes were formed at pH 5.0 in 0.1 M NaClO4, indicated by a clear red shift of the absorption maximum. The absorption spectra obtained from spectrophotometric titration were analyzed by means of factor analysis and complex stabilities were calculated to be log β110 = 2.56 ± 0.08 and log β120 = 3.93 ± 0.19. (author)
17. Standard practice for The separation of americium from plutonium by ion exchange
CERN Document Server
American Society for Testing and Materials. Philadelphia
2001-01-01
1.1 This practice describes the use of an ion exchange technique to separate plutonium from solutions containing low concentrations of americium prior to measurement of the 241Am by gamma counting. 1.2 This practice covers the removal of plutonium, but not all the other radioactive isotopes that may interfere in the determination of 241Am. 1.3 This practice can be used when 241Am is to be determined in samples in which the plutonium is in the form of metal, oxide, or other solid provided that the solid is appropriately sampled and dissolved (See Test Methods C758, C759, and C1168). 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
18. Transportability Class of Americium in K Basin Sludge under Ambient and Hydrothermal Processing Conditions
Energy Technology Data Exchange (ETDEWEB)
Delegard, Calvin H.; Schmitt, Bruce E.; Schmidt, Andrew J.
2006-08-01
This report establishes the technical bases for using a ''slow uptake'' instead of a ''moderate uptake'' transportability class for americium-241 (241Am) for the K Basin Sludge Treatment Project (STP) dose consequence analysis. Slow uptake classes are used for most uranium and plutonium oxides. A moderate uptake class has been used in prior STP analyses for 241Am based on the properties of separated 241Am and its associated oxide. However, when 241Am exists as an ingrown progeny (and as a small mass fraction) within plutonium mixtures, it is appropriate to assign transportability factors of the predominant plutonium mixtures (typically slow) to the Am241. It is argued that the transportability factor for 241Am in sludge likewise should be slow because it exists as a small mass fraction as the ingrown progeny within the uranium oxide in sludge. In this report, the transportability class assignment for 241Am is underpinned with radiochemical characterization data on K Basin sludge and with studies conducted with other irradiated fuel exposed to elevated temperatures and conditions similar to the STP. Key findings and conclusions from evaluation of the characterization data and published literature are summarized here. Plutonium and 241Am make up very small fractions of the uranium within the K Basin sludge matrix. Plutonium is present at about 1 atom per 500 atoms of uranium and 241Am at about 1 atom per 19000 of uranium. Plutonium and americium are found to remain with uranium in the solid phase in all of the {approx}60 samples taken and analyzed from various sources of K Basin sludge. The uranium-specific concentrations of plutonium and americium also remain approximately constant over a uranium concentration range (in the dry sludge solids) from 0.2 to 94 wt%, a factor of {approx}460. This invariability demonstrates that 241Am does not partition from the uranium or plutonium fraction for any characterized sludge matrix. Most
19. Reactive films for mitigating methyl bromide emissions from fumigated soil
Science.gov (United States)
Emissions of methyl bromide (MeBr) from agricultural fumigation can lead to depletion of the stratospheric ozone layer, and so its use is being phased out. However, as MeBr is still widely used under Critical Use Exemptions, strategies are still required to control such emissions. In this work, nove...
20. Depleting methyl bromide residues in soil by reaction with bases
Science.gov (United States)
Despite generally being considered the most effective soil fumigant, methyl bromide (MeBr) use is being phased out because its emissions from soil can lead to stratospheric ozone depletion. However, a large amount is still currently used due to Critical Use Exemptions. As strategies for reducing the...
1. Preozonation of bromide-bearing source water in south China
Institute of Scientific and Technical Information of China (English)
2006-01-01
The effectiveness of preozonation was evaluated on treating a bromide-bearing dam source water in south China through batch-scale experiments. Preozonation at ozone doses of 0.5-1.0 mg/L (at ozone consumption base) enhanced total organic carbon(TOC) removal through coagulation, and resulted in an almost linear reduction of ultraviolet absorbance at 254 nm (UV254). The removals of TOC (after coagulation) and UV254 at the ozone dose of 1.0 mg/L were 36% and 70%, respectively. Preozonation at an ozone dose between 0.5 and 1.0 mg/L resulted in the removal of disinfection byproducts formation potential (DBFP) including trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP) for about 50%. The removals of THMFP and HAAFP decreased with the further increase of ozone dose. Ozonation of bromide-bearing water (bromide concentration,34 μg/L) produced a bromate concentration under the detection limit(2 μg/L) at ozone doses ＜ 1.5 mg/L. However, bromate ＞10 μg/L could be produced when the bromide concentration was increased to 96 μg/L.
2. 7 CFR 305.6 - Methyl bromide fumigation treatment schedules.
Science.gov (United States)
2010-01-01
... to air temperature within the chamber. Fruit taken from a cooling room may have to be prewarmed... pure, type “Q” (for quarantine use only) methyl bromide per 1,000 cubic feet of chamber space. Dosage.... Water temperature in the volatilizer must never fall below 65.6 °C (150 °F) at any time during...
3. Residues resulting from fumigation of food commodities with methyl bromide
International Nuclear Information System (INIS)
An investigation was undertaken to determine the nature and significance of residues remaining in methyl bromide-fumigated commodities using radiotracer techniques (14C-methyl bromide). Experiments with corn showed that the germ part of the kernel contained nearly half of the total 14C-residue remaining in the seed. Also preliminary tests with granny smith apples revealed that considerable residue may remain in seeds of treated apples with less in skin and the least in the fleshy pulp. In fumigated corn, fractionation revealed that radioactive residues were distributed throughout albumins, globulins, Zein 1, Zein 2 and glutelin with a large part in the aqueous extract (amino acids). Further investigation emphasized the characterization of volatile substances resulting from alkali treatment. It was found that methyl bromide readily methylated methionine and this constitutes a major site of methylation. A component of the volatile fraction was dimethyl sulfoxide, probably a product of oxidation of dimethyl sulphide. Work is in progress to determine whether methyl bromide will methylate purine and pyrimidine components. (author)
4. Methyl bromide phase out could affect future reforestation efforts
Science.gov (United States)
Methyl bromide has long been an integral component in producing healthy tree seedlings in forest nurseries of California, Idaho, Montana, Oregon and Washington. The fumigant was supposed to be completely phased out of use in the United States of America by 2005, but many forest nurseries continue to...
5. Een ionchromatografische methode voor de simultane bepaling van nitriet, bromide en sulfiet in water
NARCIS (Netherlands)
Beld WA van den; Cleven RFMJ; LAC
1996-01-01
Betreft resultaten van een onderzoek naar het ontwikkelen van een geautomatiseerde ionchromatografische methode voor de bepaling van nitriet, bromide en sulfiet. Het onderzoek heeft geresulteerd in een betrouwbare, selectieve en gevoelige methode voor de simultane bepaling van nitriet, bromide e
6. Association of defects in lead chloride and lead bromide: Ionic conductivity and dielectric loss measurements
NARCIS (Netherlands)
Brom, W.E. van den; Schoonman, J.; Wit, J.H.W. de
1972-01-01
The ionic conductivity data of pure and doped lead bromide without associated defects are used in order to explain the anomalous conductivity behaviour of copper (I) bromide and lead oxide-doped lead-bromide crystals. In these crystals precipitated dopant and associated defects are present. The asso
7. Detection of lipopolysaccharides by ethidium bromide staining after sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
OpenAIRE
Kido, N; Ohta, M; Kato, N
1990-01-01
A rapid and easy method for staining lipopolysaccharides with ethidium bromide is described. Lipopolysaccharides could be visualized by ethidium bromide with almost the same sensitivity as found with the silver-staining method in less than 30 min. The ethidium bromide-staining method was particularly suitable for staining lipopolysaccharides possessing acidic O-specific polysaccharides, which were poorly visualized by silver staining.
8. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.
Science.gov (United States)
2010-07-01
... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...
9. Uptake of ozone to mixed sodium bromide/ citric acid solutions
Science.gov (United States)
Lee, Ming-Tao; Steimle, Emilie; Bartels-Rausch, Thorsten; Kato, Shunsuke; Lampimäki, Markus; Brown, Matthew; van Bokhoven, Jeroen; Nolting, Frithjof; Kleibert, Armin; Türler, Andreas; Ammann, Markus
2013-04-01
Sea-salt solution - air interfaces play an important role in the chemistry of the marine boundary layer. The reaction of ozone (O3) with bromide is of interest in the context of formation of photolabile halogens (Br2, BrCl) in the marine boundary layer. Recent experiments have suggested that the bromide oxidation rate is related to the surface concentration of bromide [1] and inversely related to the gas phase concentration of O3, an indication for a precursor mediated reaction at the surface [2]. So far, the effect of organics (such as those occurring at the ocean surface or in marine aerosols) on the reaction of O3 with bromide aerosols has not been studied yet. In our study we investigate the uptake kinetics of O3 to a mixed solution of sodium bromide (NaBr) and citric acid (CA), which represents highly oxidized organic compounds present in the environment, with a well-established coated wall flow tube technique, which leads to exposure of the film to O3 allowing the heterogeneous reactions to take place and the loss of O3 being measured. The results indicate that the uptake of O3 to the films with the higher bromide concentrations (0.34M and 4M) is independent of the gas phase concentration and roughly consistent with uptake limited by reaction in the bulk. For the lower bromide concentration (84mM), however, we observe a trend of the uptake coefficient to decrease with increasing O3 concentration, indicating an increasing importance of a surface reaction. In an attempt to constrain the kinetic data, we employed X-ray photoelectron spectroscopy (XPS) to get insight into the surface composition of the aqueous solution - air interface. Previous XPS studies have shown that halide ion concentrations are enhanced at the aqueous solution air interface [3-4], which likely promotes the surface reactions of bromide or iodide with O3. A first XPS study of ternary solutions of KI with butanol indicated the importance of specific interactions of the cation with the alcohol
10. A comparison of the effect of intranasal desmopressin and intramuscular hyoscine N-butyl bromide combination with intramuscular hyoscine N-butyl bromide alone in acute renal colic
OpenAIRE
2010-01-01
Background: Patients with acute renal colic usually require immediate diagnosis and treatment. In this clinical trial analgesic effect of hyoscine N-butyl bromide and desmopressin combination in comparison with hyoscine N-butyl bromide alone in patients with acute renal colic induced by urinary stones was assessed. Methods: The study included 114 patients randomly allocated in two groups (A and B). Patients in group A received 20 mg intramuscular hyoscine N-butyl bromide at admission tim...
11. Aluminium Electroplating on Steel from a Fused Bromide Electrolyte
Energy Technology Data Exchange (ETDEWEB)
Prabhat Tripathy; Laura Wurth; Eric Dufek; Toni Y. Gutknecht; Natalie Gese; Paula Hahn; Steven Frank; Guy Fredrickson; J Stephen Herring
2014-08-01
A quaternary bromide bath (LiBr-KBr-CsBr-AlBr3) was used to electro-coat aluminium on steel substrates. The electrolyte was prepared by the addition of AlBr3 into the eutectic LiBr-KBr-CsBr melt. A smooth, thick, adherent and shiny aluminium coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminium coverage. Both salt immersion and open circuit potential measurement suggest that the coatings did display good corrosion-resistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminium coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminium coating on both ferrous and non-ferrous metals, including complex surfaces/geometries.
12. [2,6-Bis(dimethylaminomethylphenyl]selenium bromide monohydrate
Directory of Open Access Journals (Sweden)
Richard A. Varga
2010-04-01
Full Text Available In the title hydrated molecular salt, C12H19N2Se+·Br−·H2O, the two independent bromide anions lie on a twofold rotation axis. Strong intramolecular N→Se interactions [2.185 (3 and 2.181 (3 Å] are established by both N atoms of the organic group in the cation, in trans positions to each other, with an N—Se—N angle of 161.6 (1°, resulting in a T-shaped (C,N,N′Se core. In the crystal, dimeric associations are formed by Br...Se [3.662 (2 Å] and Br...H interactions [2.56 (6 and 2.63 (7 Å] involving two bromide anions, two cations and two water molecules.
13. Preparation of ethyl magnesium bromide for regiospecific analysis of triacylglycerols.
Science.gov (United States)
Ando, Yasuhiro; Tomita, Yuki; Haba, Yusuke
2008-01-01
This paper presents a procedure for preparation of a Grignard reagent, ethyl magnesium bromide, used for partial deacylation of triacylglycerols (TAG) in their regiospecific analysis. Magnesium turnings were reacted with ethereal solution of bromoethane in a screw-capped test tube to synthesize 2 mL of 1 M ethyl magnesium bromide. Continuously stirred with a vortex mixer, the reaction smoothly proceeded at room temperature. Regiospecific analysis of 1,3-distearoyl-2-oleoylglycerol using this product showed that fatty acid compositions of the sn-1(3) and sn-2 positions were contaminated by less than 2 mol% of fatty acids migrated from isomeric positions. The analyses of lard and cod liver/mackerel oil TAG showed typical distribution patterns of 16:0, 22:5n-3 and 22:6n-3 in pig and fish depot TAG. These results confirmed the view that the freshly prepared reagent is usable for regiospecific analysis of TAG.
14. The behaviour under irradiation of molybdenum matrix for inert matrix fuel containing americium oxide (CerMet concept)
Science.gov (United States)
D'Agata, E.; Knol, S.; Fedorov, A. V.; Fernandez, A.; Somers, J.; Klaassen, F.
2015-10-01
Americium is a strong contributor to the long term radiotoxicity of high activity nuclear waste. Transmutation by irradiation in nuclear reactors or Accelerator Driven System (ADS, subcritical reactors dedicated to transmutation) of long-lived nuclides like 241Am is therefore an option for the reduction of radiotoxicity of waste packages to be stored in a repository. In order to safely burn americium in a fast reactor or ADS, it must be incorporated in a matrix that could be metallic (CerMet target) or ceramic (CerCer target). One of the most promising matrix to incorporate Am is molybdenum. In order to address the issues (swelling, stability under irradiation, gas retention and release) of using Mo as matrix to transmute Am, two irradiation experiments have been conducted recently at the High Flux Reactor (HFR) in Petten (The Netherland) namely HELIOS and BODEX. The BODEX experiment is a separate effect test, where the molybdenum behaviour is studied without the presence of fission products using 10B to "produce" helium, the HELIOS experiment included a more representative fuel target with the presence of Am and fission product. This paper covers the results of Post Irradiation Examination (PIE) of the two irradiation experiments mentioned above where molybdenum behaviour has been deeply investigated as possible matrix to transmute americium (CerMet fuel target). The behaviour of molybdenum looks satisfying at operating temperature but at high temperature (above 1000 °C) more investigation should be performed.
15. Consideration of the effect of lymph-node deposition upon the measurement of plutonium and americium in the lungs
International Nuclear Information System (INIS)
Measurement of an inhaled radionuclide by external photon counting includes quantities which may be contained in lymph nodes, as well as quantities in the lungs. An overestimate of the lung burden can result, if a portion of the radionuclide were present in the lymph nodes. This problem is analyzed with respect to the measurement of inhaled plutonium containing plutonium-241 and americium-241, when americium-241 has been used as a tracer for the plutonium. Equations are derived which yield the amounts of americium and of plutonium in the lungs and in the lymph nodes as a function of time after exposure and for various translocation and retention parameters. Count histories (count profiles) of actual exposure cases are compared with calculated count profiles in order to gain insight into possible values of the translocation and retention parameters. Comparison is also made with calculated count profiles using values of translocation and retention parameters recommended by the International Commission on Radiological Protection (ICRP) for use with the Task Group Lung Model. The magnitude of the possible overestimate (error factor) was calculated for combinations o
16. HELIOS: the new design of the irradiation of U-free fuels for americium transmutation
Energy Technology Data Exchange (ETDEWEB)
D' Agata, E. [European Commission, Joint Research Centre, Institute for Energy, P.O. Box 2, 1755 ZG Petten (Netherlands); Klaassen, F.; Sciolla, C. [Nuclear Research and Consultancy Group, Dept. Life Cycle and Innovations, P.O. Box 25 1755 ZG Petten (Netherlands); Fernandez-Carretero, A. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Bonnerot, J.M. [Commissariat a l' Energie Atomique, DEC/SESC/LC2I CEA-Cadarache, 13108 St. Paul lez Durance Cedex (France)
2009-06-15
Americium is one of the radioactive elements that mostly contribute to the radiotoxicity of the nuclear spent fuel. Transmutation of long-lived nuclides like Americium is an option for the reduction of the mass, the radiotoxicity and the decay heat of nuclear waste. The HELIOS irradiation experiment is the last evolution in a series of experiments on americium transmutation. The previous experiments, EFTTRA-T4 and T4bis, have shown that the release or trapping of helium is the key issue for the design of such kind of target. In fact, the production of helium, which is characteristic of {sup 241}Am transmutation, is quite significant. The experiment is carried out in the framework of the 4-year project EUROTRANS of the EURATOM 6. Framework Programme (FP6). Therefore, the main objective of the HELIOS experiment is to study the in-pile behaviour of U-free fuels such as CerCer (Pu, Am, Zr)O{sub 2} and Am{sub 2}Zr{sub 2}O{sub 7}+MgO or CerMet (Pu, Am)O{sub 2}+Mo in order to gain knowledge on the role of the fuel microstructure and of the temperature on the gas release and on the fuel swelling. The experiment was planned to be conducted in the HFR (High Flux Reactor) in Petten (The Netherlands) starting the first quarter of 2007. Because of the innovative aspects of the fuel, the fabrication has had some delays as well as the final safety analyses of the original design showed some unexpected deviation. Besides, the HFR reactor has been unavailable since August 2008. Due to the reasons described above, the experiment has been postponed. HELIOS should start in the first quarter of 2009 and will last 300 full power days. The paper will cover the description of the new design of the irradiation experiment HELIOS. The experiment has been split in two parts (HELIOS1 and HELIOS2) which will be irradiated together. Moreover, due to the high temperature achieved in cladding and to the high amount of helium produced during transmutation the experiment previously designed for a
17. High-speed Laser Micromachining with Copper Bromide Laser
CERN Document Server
Balchev, I I; Minkovski, N I; Sabotinov, N V; Balchev, Ivaylo I.; Kostadinov, Ivan K.; Minkovski, Nikolai I.; Sabotinov, Nikola V.
2006-01-01
The application of the copper bromide (CuBr) laser as an attractive tool in the micro-machining of different materials has been demonstrated. High-quality drilling by trepanning and precision cutting was established on several materials with a negligible heat-affected zone (HAZ). That good performance was a result of the combination of high power visible radiation, short pulses, and close to the diffraction-limited laser beam quality with high-speed galvo scanner beam steering.
18. Criticality in aqueous solutions of 3-methylpyridine and sodium bromide.
Science.gov (United States)
Kostko, A F; Anisimov, M A; Sengers, J V
2004-08-01
We address a controversial issue regarding the nature of critical behavior in ternary electrolyte solutions of water, 3-methylpyridine, and sodium bromide. Earlier light-scattering studies showed an anomalous critical behavior in this system that was attributed to the formation of a microheterogeneous phase associated with ion-molecule clustering [M.A. Anisimov, J. Jacob, A. Kumar, V.A. Agayan, and J. V. Sengers, Phys. Rev. Lett. 85, 2336 (2000)
19. Comparison of Heat and Bromide as Ground Water Tracers Near Streams
Science.gov (United States)
Constantz, J.; Cox, M.H.; Su, G.W.
2003-01-01
Heat and bromide were compared as tracers for examining stream/ground water exchanges along the middle reaches of the Santa Clara River, California, during a 10-hour surface water sodium bromide injection test. Three cross sections that comprise six shallow (sodium bromide injection test. Vertical, one-dimensional simulations of bromide concentrations in the sediments yielded a good match to the observed bromide concentrations, without adjustment of any model parameters except solute dispersivities. This indicates that, for the spatial and temporal scales examined on the Santa Clara River, the use of heat and bromide as tracers provide comparable information with respect to apparent hydraulic conductivities and fluxes for sediments near streams. In other settings, caution should be used due to differences in the nature of conservative (bromide) versus nonconservative (heat) tracers, particularly when preferential flowpaths are present.
20. Use of 82Br and 131I radionuclides in studies of goitrogenic effects of exogenous bromide
International Nuclear Information System (INIS)
The interference of excessive bromide intake with iodine metabolism in the rat was studied using 82Br and 131I radionuclides. Mainly lactating rat dams and their pups were used, in addition to adult male rats, in the present studies. Particularly, the influence of high bromide intake in lactating rat dams on the transfer of iodine and bromide to suckling young through breast milk was evaluated. The induction of hypothyroid status in the pups by high bromide intake in the mothers was proved unambiguously. Excessive bromide in lactating rat dams caused a marked decrease in plasma levels of thyroid hormones both, in the mothers and in their sucklings. The effects of an enhanced bromide intake on the thyroid function in relation to iodine status in the animals were also followed. Marked goitrogenic and thyrotoxic effects of excessive bromide in adult rats were significantly enhanced under the conditions of simultaneous iodine deficiency in the experimental animals. (author)
1. [Manometric effects of pinaverium bromide in irritable bowel syndrome].
Science.gov (United States)
Soifer, L; Varela, E; Olmos, J
1992-01-01
The effects of pinaverium bromide on colonic motility were investigated in a controlled, controlled, cross-over study in 32 patients with irritable bowel syndrome. Constipation was clearly predominant in one group of 16 patients, and diarrhea in the other group of 16. Manometric measurements were taken of the colonic motor response generated by distention of a balloon inserted to the rectosigmoid junction. Measurements were taken before and one hour after ingestion of two tablets containing placebo or two tablets each containing 50 mg of pinaverium bromide. Following intake of placebo the motility index increased from the basal value in patients with constipation, and resistance to distention decreased in the diarrhea group. These changes were attributable to repetition of the mechanical stimulus within a relatively brief time lapse, or more probably to the ingestion of liquid which accompanied intake of tablets. Compared with placebo, pinaverium bromide induced inhibition of both effects. From the therapeutic point of view, the decrease in motility index seen in patients with irritable bowel syndrome and constipation is particularly interesting. PMID:1295286
2. 4-Hydroxy-1,2,6-trimethylpyridinium bromide monohydrate
Directory of Open Access Journals (Sweden)
T. Seethalakshmi
2013-06-01
Full Text Available The title salt, C8H12NO+·Br−·H2O, is isomorphous with the chloride analogue [Seethalakshmi et al. (2013. Acta Cryst. E69, o835–o836]. In the solid state, the cations, anions and water molecules are interlinked by a network of O—H...O, O—H...Br and C—H...Br interactions. The water molecule makes two O—H...Br hydrogen bonds, generating [010] zigzag chains of alternating water molecules and bromide anions. The cation is involved in two intermolecular C—H...Cl interactions in the chloride salt, whereas three intermolecular C—H...Br interactions are observed in the title bromide salt. This additional intermolecular C—H...Br interaction links the adjacent water and bromide zigzag chains via cationic molecules. In addition, weak π–π stacking interactions are observed between pyridinium rings [centroid–centroid distance = 3.5664 (13 Å].
3. Structural, vibrational and theoretical studies of L-histidine bromide
Science.gov (United States)
Ahmed, A. Ben; Feki, H.; Abid, Y.; Boughzala, H.; Mlayah, A.
2008-10-01
This paper presents the results of our calculations of the geometric parameters, vibrational spectra and hyperpolarizability of a non linear optical material, L-histidine bromide. Due to the lack of sufficiently precise information on the geometric structure available in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystals of L-histidine bromide have been grown by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro symmetric space group P2 12 12 1 of the orthorhombic system. Raman spectra have been recorded in the range [200-3500 cm -1]. All observed vibrational bands have been discussed and assigned to normal mode or to combinations and overtones on the basis of our calculations. The optimized geometric bond lengths and bond angles obtained by using HF and DFT (B3LYP and BLYP) show good agreement with the experimental data. Comparison between the measured and the calculated vibrational frequencies indicate that B3LYP is superior to the scaled HF approach for molecular vibrational problems. To investigate microscopic second order non linear optical properties of L-histidine bromide, the electric dipole μ, the polarizability α and the hyperpolarizability β were computed using DFT//B3LYP/6-31G(d) method. According to our calculations, the title compound exhibits non-zero β value revealing microscopic second order NLO behaviour.
4. Oral teratogenicity studies of methyl bromide in rats and rabbits.
Science.gov (United States)
Kaneda, M; Hojo, H; Teramoto, S; Maita, K
1998-05-01
Teratogenicity studies of methyl bromide, a widely used fumigant, were conducted in rats and rabbits. Methyl bromide was dissolved in corn oil and administered orally to groups of 24 copulated female Crj:CD (SD) rats at dose levels of 0 (corn oil), 3, 10 or 30 mg/kg/day on days 6-15 of gestation and to groups of 18 artificially inseminated female Kbl:JW rabbits at 0, 1, 3 or 10 mg/kg/day on days 6-18 of gestation. Maternal rats and rabbits were euthanized on respective days 20 and 27 of gestation. Foetuses were examined for survival, growth and teratological alterations. Maternal toxicity was evident in the high-dose groups for both species. In these groups, maternal body weight gains and food consumption were significantly decreased during the dosing and post-dosing periods. Necropsy of maternal rats also revealed erosive lesions in the stomach and the surrounding organs. However, no treatment-related adverse effects were found in foetuses of the treated groups for both rat and rabbit studies. These results led to the conclusion that methyl bromide was not foetotoxic or teratogenic to rat and rabbit foetuses up to dose levels of 30 and 10 mg/kg/day, respectively, at which maternal toxicity was evident for both species.
5. Anomalous aryl strengthening of complexes at americium and europium extraction with alkylenediphospine dioxide from perchloric media
International Nuclear Information System (INIS)
Studied was the extraction of americium(3) and europium(3) from perchlorate solutions(0.001 M) with dioxides of alkylenediphosphines of three types: aryl Ph2P(O)CH2(O)PPh2(briefly 4P), and Ph2P(O)(CH2)2(O)PPh2, mixed Ph2P(O)CH2(O)P(C8H17)2 (or 2Ph2Oct) and alkyl (C8H17)2P(O)CH2(O)P(C8H17)2 (or 4 Oct). Trisolvates of MeS3x(ClO4)3 are predominantly formed but americium disolvates are also present upon dilution with dichloroethane. For 4Ph,2Ph2Oct and 4 Oct the concentration is, respectively, 1015, 2x1014, and 1013; for disolvates by 4 orders of magnitude lower which is, nevertheless, by 2 orders of magnitude higher than for nitric acid solutions. The separation coefficient of β Am/Eu for 4Ph attains 6-8. As in the case of nitrate solutions, an anomalous aryl strengthening of the complexes is observed: an increase in the distribution coefficients and extraction constants in the series of 4 Oct - 2Ph 2 Oct - 4Ph, in spite of the introduction of electronegative aryl substituents into the dioxide molecule, which reduce electron density on oxygen atoms and basicity of dioxides. In contrast to nitric acid solutions, observed is a nonlinear effect of a change in basicity on extraction properties upon dilution with dichloroethane (dioxide of 2Ph2 Oct does not occupy an intermediate position but is close to 4Ph). Upon dilution with chloroform the dependence is linear and anomalous effect rises due to a different nature of interactions of dioxides with chloroform. When the bridge increases up to ethylene, an anomalous strengthening of the complexes disappears. However, the distribution coefficients upon extraction with alkyl dioxide are considerably lower, which can be explained by a stronger extraction of perchloric acid
6. Solid miscibility of common-anion lithium and sodium halides. Experimental determination of the region of demixing in lithium bromide + sodium bromide
NARCIS (Netherlands)
Oonk, H.A.J.; Wijk, H.J. van; Doornhof, D.
1984-01-01
The region of demixing of solid lithium bromide + sodium bromide mixtures has been measured by X-ray diffraction. The critical temperature of mixing corresponding to a thermodynamic fit of the experimental data is 513 K. Estimates are given of the regions of demixing in solid lithium chloride + sodi
7. Americium-based oxides: Dense pellet fabrication from co-converted oxalates
Energy Technology Data Exchange (ETDEWEB)
Horlait, Denis; Lebreton, Florent [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze (France); Gauthé, Aurélie [CEA, DEN, DRCP/SERA/LCAR, 30207 Bagnols-sur-Cèze (France); Caisso, Marie [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze (France); Arab-Chapelet, Bénédicte; Picart, Sébastien [CEA, DEN, DRCP/SERA/LCAR, 30207 Bagnols-sur-Cèze (France); Delahaye, Thibaud, E-mail: thibaud.delahaye@cea.fr [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze (France)
2014-01-15
Mixed oxides are used as nuclear fuels and are notably envisaged for future fuel cycles including plutonium and minor actinide recycling. In this context, processes are being developed for the fabrication of uranium–americium mixed-oxide compounds for transmutation. The purpose of these processes is not only the compliance with fuel specifications in terms of density and homogeneity, but also the simplification of the process for its industrialization as well as lowering dust generation. In this paper, the use of a U{sub 0.85}Am{sub 0.15}O{sub 2±δ} powder synthesized by oxalate co-conversion as a precursor for dense fuel fabrications is assessed. This study notably focuses on sintering, which yielded pellets up to 96% of the theoretical density, taking advantage of the high reactivity and homogeneity of the powder. As-obtained pellets were further characterized to be compared to those obtained via processes based on the UMACS (Uranium Minor Actinide Conventional Sintering) process. This comparison highlights several advantages of co-converted powder as a precursor for simplified processes that generate little dust.
8. Study of biosorbents application on the treatment of radioactive liquid wastes with americium-241
International Nuclear Information System (INIS)
The use of nuclear energy for many different purposes has been intensified and highlighted by the benefits that it provides. Medical diagnosis and therapy, agriculture, industry and electricity generation are examples of its application. However, nuclear energy generates radioactive wastes that require suitable treatment ensuring life and environmental safety. Biosorption and bioaccumulation represent an emergent alternative for the treatment of radioactive liquid wastes, providing volume reduction and physical state change. This work aimed to study biosorbents for the treatment of radioactive liquid wastes contaminated with americium-241 in order to reduce the volume and change the physical state from liquid to solid. The biosorbents evaluated were Saccharomyces cerevisiae immobilized in calcium alginate beads, inactivated and free cells of Saccharomyces cerevisiae, calcium alginate beads, Bacillus subtilis, Cupriavidus metallidurans and Ochrobactrum anthropi. The results were quite satisfactory, achieving 100% in some cases. The technique presented in this work may be useful and viable for implementing at the Waste Management Laboratory of IPEN - CNEN/SP in short term, since it is an easy and low cost method. (author)
9. Mutual separation of americium(III) and europium(III) using glycolamic acid and thioglycolamic acid
Energy Technology Data Exchange (ETDEWEB)
Suneesh, A.S.; Venkatesan, K.A.; Syamala, K.V.; Antony, M.P.; Vasudeva Rao, P.R. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.
2012-07-01
The extractants, bis(2-ethylhexyl)diglycolamicacid (HDEHDGA) and bis(2-ethylhexy)thiodiglycolamic acid (HDEHSDGA) were synthesized and characterized by {sup 1}H and {sup 13}C NMR, mass and IR spectroscopy. The extraction behaviour of {sup (152+154})Eu(III) and {sup 241}Am(III) from nitric acid medium by a solution of HDEHDGA (or HDEHSDGA) in n-dodecane (n-DD) was studied for the mutual separation of actinides and lanthanides. The effect of various parameters such as the pH, concentrations of HDEHDGA, HDEHSDGA, sodium nitrate, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) and diethylenetriaminepentaacetic acid (DTPA) on the separation factor (SF) of americium(III) over europium(III) and vice versa was studied, and the conditions needed for the preferential separation were optimised. The results show that HDEHDGA exhibits higher extraction for {sup (152+154)}Eu(III) and HDEHSDGA shows the superior selectivity for {sup 241}Am(III). (orig.)
10. Determination of plutonium americium and curium in soil samples by solvent extraction with trioctylphosphine oxide
International Nuclear Information System (INIS)
A method of Pu, Am and Cm determination in soil samples, which was developed for analyzing samples from territories subjected to radioactive contamination as a result of the Chernobyl accident is described. After preliminary treatment the samples were leached by solution of 7 mol/l HNO23+0.3 mol/l KBrO3 during heating. Pu was isolated by extraction with 0.05 mol TOPO from 7 mol/l HNO3. 144Ce and partially remaining in water phase isotopes of Zr, U and Th were isolated in an extraction-chromatographic column with TOPO and PbO2. Then Am and Cm were extracted by 0.2 mol/l TOPO from solution 1 mol/l HLact+0.07 mol/l DTPA+1 mol/l Al(NO3)3. Alpha-activity of both extracted products was determined in liquid scintillation counter. Chemical yield of plutonium counted to 85±10%, that of americium and curium -75±10%. 17 refs
11. Development and Testing of an Americium/Lanthanide Separation Flowsheet Using Sodium Bismuthate
Energy Technology Data Exchange (ETDEWEB)
Jack Law; Bruce Mincher; Troy Garn; Mitchell Greenhalgh; Nicholas Schmitt; Veronica Rutledge
2014-04-01
The separation of Am from the lanthanides and curium is a key step in proposed advanced fuel cycle scenarios. The partitioning and transmutation of Am is desirable to minimize the long-term heat load of material interred in a future high-level waste repository. A separation process amenable to process scale-up remains elusive. Given only subtle chemistry differences within and between the ions of the trivalent actinide and lanthanide series this separation is challenging ; however, higher oxidation states of americium can be prepared using sodium bismuthate and separated via solvent extraction using diamylamylphosphonate (DAAP) extraction. Among the other trivalent metals only Ce is also oxidized and extracted. Due to the long-term instability of Am(VI) , the loaded organic phase is readily selectively stripped to partition the actinide to a new acidic aqueous phase. Batch extraction distribution ratio measurements were used to design a flowsheet to accomplish this separation. Additionally, crossflow filtration was investigated as a method to filter the bismuthate solids from the feed solution prior to extraction. Results of the filtration studies, flowsheet development work and flowsheet performance testing using a centrifugal contactor are detailed.
12. Speciation and bioavailability of Americium-241 in the fresh water environment
International Nuclear Information System (INIS)
Due to its anthropogenic origin, the transuranic americium 241 confronts physiologists with the intriguing question, which mechanisms are involved in the incorporation or elimination of such artificial elements in biological cycles. The investigations on the speciation and bioavailability of 241Am in the freshwater environment aim to establish a relation between the behavior of 241Am in freshwater ecosystems and its availability for biota. In the limnic environment, most often characterized by a high organic load and a low conductivity, the effect of complexation of 241Am with humic acids and competition with trivalent cations such as A1 and Fe, were proven to be significant on the speciation of 241Am. Based on the registration of the 241Am uptake by a large number of freshwater organisms, the crayfish Astacus leptodactylus Eschscholtz was chosen to study the whole-body uptake of 241Am, its corresponding organ distribution and its retention in the animal. The share of external fixation and ingestion in the global uptake, and the effect of speciation on it, were studied more carefully. Other aspects in this physiological part were: the kinetics of 241Am in the hemolymph and the hepatopancreas, and its subcellular distribution in the digestive gland. Finally, by comparing the physiology of 241Am with some other metals (240Pu, 64Cu, 198Au) with analogous or contradictional properties, we tried to find out whether the behavior of 241Am in organisms can be explained from its chemical characteristics
13. Solution speciation of plutonium and Americium at an Australian legacy radioactive waste disposal site.
Science.gov (United States)
Ikeda-Ohno, Atsushi; Harrison, Jennifer J; Thiruvoth, Sangeeth; Wilsher, Kerry; Wong, Henri K Y; Johansen, Mathew P; Waite, T David; Payne, Timothy E
2014-09-01
During the 1960s, radioactive waste containing small amounts of plutonium (Pu) and americium (Am) was disposed in shallow trenches at the Little Forest Burial Ground (LFBG), located near the southern suburbs of Sydney, Australia. Because of periodic saturation and overflowing of the former disposal trenches, Pu and Am have been transferred from the buried wastes into the surrounding surface soils. The presence of readily detected amounts of Pu and Am in the trench waters provides a unique opportunity to study their aqueous speciation under environmentally relevant conditions. This study aims to comprehensively investigate the chemical speciation of Pu and Am in the trench water by combining fluoride coprecipitation, solvent extraction, particle size fractionation, and thermochemical modeling. The predominant oxidation states of dissolved Pu and Am species were found to be Pu(IV) and Am(III), and large proportions of both actinides (Pu, 97.7%; Am, 86.8%) were associated with mobile colloids in the submicron size range. On the basis of this information, possible management options are assessed. PMID:25126837
14. Solution speciation of plutonium and Americium at an Australian legacy radioactive waste disposal site.
Science.gov (United States)
Ikeda-Ohno, Atsushi; Harrison, Jennifer J; Thiruvoth, Sangeeth; Wilsher, Kerry; Wong, Henri K Y; Johansen, Mathew P; Waite, T David; Payne, Timothy E
2014-09-01
During the 1960s, radioactive waste containing small amounts of plutonium (Pu) and americium (Am) was disposed in shallow trenches at the Little Forest Burial Ground (LFBG), located near the southern suburbs of Sydney, Australia. Because of periodic saturation and overflowing of the former disposal trenches, Pu and Am have been transferred from the buried wastes into the surrounding surface soils. The presence of readily detected amounts of Pu and Am in the trench waters provides a unique opportunity to study their aqueous speciation under environmentally relevant conditions. This study aims to comprehensively investigate the chemical speciation of Pu and Am in the trench water by combining fluoride coprecipitation, solvent extraction, particle size fractionation, and thermochemical modeling. The predominant oxidation states of dissolved Pu and Am species were found to be Pu(IV) and Am(III), and large proportions of both actinides (Pu, 97.7%; Am, 86.8%) were associated with mobile colloids in the submicron size range. On the basis of this information, possible management options are assessed.
15. Interaction between gaseous ozone and crystalline potassium bromide
Science.gov (United States)
Levanov, A. V.; Maksimov, I. B.; Isaikina, O. Ya.; Antipenko, E. E.; Lunin, V. V.
2016-07-01
The formation of nonvolatile products of the oxidation of a bromide ion during the interaction between gaseous ozone and powdered crystalline KBr is studied. It is found that potassium bromate KBrO3 is the main product of the reaction. The influence of major experimental factors (the duration of ozonation, the concentration of ozone, the humidity of the initial gas, and the temperature) on the rate of formation of bromate is studied. The effective constants of the formation of bromate during the interaction between O3 and Br- in a heterogeneous gas-solid body system and in a homogeneous aqueous solution are compared.
16. Suicide by intravenous injection of rocuronium-bromide: Case report
Directory of Open Access Journals (Sweden)
Nikolić Slobodan
2005-01-01
Full Text Available Suicides by intravenous injection of an overdose of medicaments are uncommon. In this paper, we present the case of a suicide by rocuronium-bromide injection in combination with an oral overdose of metoprolol. Unfortunately, in Belgrade, there is no toxicological laboratory capable of detecting rocuronium. The interpretation of autopsy and toxicological data in this case was made difficult due to the extreme putrefaction of the body of the deceased. So, by forensic investigation, the case was solved indirectly, through circumstantial evidence: an empty ampoule of rocuronium found near the body, as well as a plastic syringe and cloth-bandage found in the left hand of the deceased.
17. Methyl bromide: Ocean sources, ocean sinks, and climate sensitivity
OpenAIRE
A. D. Anbar; Yung, Y. L.; Chavez, F.P.
1996-01-01
The oceans play an important role in the geochemical cycle of methyl bromide (CH_3Br), the major carrier of O_3-destroying bromine to the stratosphere. The quantity of CH_3Br produced annually in seawater is comparable to the amount entering the atmosphere each year from natural and anthropogenic sources. The production mechanism is unknown but may be biological. Most of this CH_3Br is consumed in situ by hydrolysis or reaction with chloride. The size of the fraction which escapes to the atmo...
18. Enzyme activities in agricultural soils fumigated with methyl bromide alternatives
OpenAIRE
Klose, Susanne; Ajwa, H A
2004-01-01
Pre-plant fumigation of agricultural soils with a combination of methyl bromide (MeBr) and chloropicrin (CP) to control nematodes, soil-borne pathogens and weeds has been a common practice in strawberry (Fragaria X ananassa Duchesne) production since the 1960s. MeBr will be phased out by 2005, but little is known about the impacts of alternative fumigants on soil microbial processes. We investigated the response of microbial biomass and enzyme activities in soils fumigated over two years with...
19. Automated determination of bromide in waters by ion chromatography with an amperometric detector
Science.gov (United States)
Pyen, G.S.; Erdmann, D.E.
1983-01-01
An automated ion chromatograph, including a program controller, an automatic sampler, an integrator, and an amperometric detector, was used to develop a procedure for the determination of bromide in rain water and many ground waters. Approximately 10 min is required to obtain a chromatogram. The detection limit for bromide is 0.01 mg l-1 and the relative standard deivation is <5% for bromide concentrations between 0.05 and 0.5 mg l-1. Chloride interferes if the chloride-to-bromide ratio is greater than 1 000:1 for a range of 0.01-0.1 mg l-1 bromide; similarly, chloride interferes in the 0.1-1.0 mg l-1 range if the ratio is greater than 5 000:1. In the latter case, a maximum of 2 000 mg l-1 of chloride can be tolerated. Recoveries of known concentrations of bromide added to several samples, ranged from 97 to 110%. ?? 1983.
20. Effects of pinaverium bromide and verapamil on the motility of the rat isolated colon.
Science.gov (United States)
Baumgartner, A; Drack, E; Halter, F; Scheurer, U
1985-09-01
Pinaverium bromide was 30 times less potent than verapamil in inhibiting intraluminal pressure responses of in vitro rat colonic segments to barium chloride, acetylcholine, FK 33-824 or field stimulation. The inhibitory effects of both verapamil and pinaverium bromide on the pressure responses to field stimulation were antagonized similarly by exogenous calcium administration. These results support the concept that pinaverium bromide acts on calcium channels in the smooth muscle cell membrane. PMID:4052731
1. Effects of pinaverium bromide and verapamil on the motility of the rat isolated colon.
OpenAIRE
Baumgartner, A.; Drack, E.; Halter, F; Scheurer, U.
1985-01-01
Pinaverium bromide was 30 times less potent than verapamil in inhibiting intraluminal pressure responses of in vitro rat colonic segments to barium chloride, acetylcholine, FK 33-824 or field stimulation. The inhibitory effects of both verapamil and pinaverium bromide on the pressure responses to field stimulation were antagonized similarly by exogenous calcium administration. These results support the concept that pinaverium bromide acts on calcium channels in the smooth muscle cell membrane.
2. A study of plutonium and americium concentrations in seaspray on the southern Scottish coast
International Nuclear Information System (INIS)
Seaspray and seawater have been collected from the southern Scottish coast and, for comparison, Cumbria in northwest England during 1989 and 1991. The occurrence of sea-to-land transfer of the actinides plutonium and americium in seaspray was observed on these coasts using muslin screens (a semi-quantitative technique most efficient for collecting large spray droplets) and high volume conventional air samplers. The actinides and fine particulate in the spray were present in relatively higher concentrations than measured in the adjacent seawater, i.e. the spray was enriched in particulate actinides. The net efficiency of the muslim screens in collecting airborne plutonium isotopes and 241Am generally appeared to be about 20%. A review of earlier published concentrations of 239+240Pu and 241Am measured in aerosol and deposition for over a year several tens of metres inland was carried out. This suggested that airborne activities are up to a factor of 5 times higher in Cumbria than southern Scotland. However, neither the new data collected in 1989 and 1991 nor this older data suggests any enhancement of seaspray actinide enrichment in southern Scotland compared to Cumbria. This finding contrasts with earlier, more limited, comparisons that have been carried out which suggested such a difference. There is clear evidence of considerable localised spatial and temporal variability in aerosol actinide enrichment over the beaches in both areas. Enrichments varies between 20 and 500 relative to the adjacent surf zone waters. However, the average enrichment in spray based on the continuous measurements made further inland is likely to be at the lower end of this range. (author)
3. Biosorption of Americium-242 by saccharomyces cerevisiae: preliminary evaluation and mechanism
International Nuclear Information System (INIS)
As an important radioisotope in nuclear industry and other fields, americium-241 is one of the most serious contamination concerns duo to its high radiation toxicity and long half-life. In this experiment, the biosorption of 241Am from solution by a fungus, Saccharomyces cerevisiae (S. cerevisiae), and the effects of various experimental conditions on the biosorption and the mechanism were explored. The preliminary results showed that S. cerevisiae is a very efficient biosorbent. An average of more than 99% of the total 241Am could be removed by S. cerevisiae of 2.1g/L (dry weight) from 241Am solutions of 2.22MBq/L -555 MBq/L (Co). The adsorption equilibrium was achieved within 1 hour and the optimum pH ranged 1-3. The culture times of more than 16 hours were suitable and the efficient adsorption of 241Am by the S. cerevisiae could be noted. The biosorption of 241Am by the decomposed cell wall, protoplasm or cell membrane of S. cerevisiae was same efficient as by the intact fungus, but the some components of S. cerevisiae, such as protein and acylation group had obvious effect on adsorption. When the concentrations of coexistent Eu3+, Nd3+ were 100 times more than that of 241Am, the adsorption rates would drop to 65%. However, most of the investigated acidic ions have no significant influence on the 241Am adsorption but minute change of pH value, while the saturated EDTA can strong inhibit the biosorption of 241Am.. (authors)
4. Transport of plutonium, americium, and curium from soils into plants by roots
International Nuclear Information System (INIS)
For assessing the dose from radionuclides in agricultural products by ingestion it is necessary to know the soil to plant transfer factors. The literature was entirely investigated, in order to judge the size of the soil to plant transfer factors. In total, 92 publications - from 1948 to 1978 -have been evaluated. As result, transfer factors from 10-9 to 10-3 have been found for Plutonium, and from 10-6 to 1 for Americium. For Curium only few data are available in literature. The considerable variation of the measured transfer factors is based on the dependence of these transfer factors from the ion exchange capacity of soils, from the amount of organic materials, from the pH-value, and from the mode of contamination. There are, in any case, contradictory data, although there has been detected a dependence of the transfer factors from these parameters. Chelating agenst increase the transfer factors to approximately 1300. As well, fertilizers have an influence on the size of the transfer factors - however, the relationships have been scarcely investigated. The distribution of actinides within the individual parts of plants has been investigated. The highest concentrations are in the roots; in the plant parts above ground the concentration of actinides decreases considerably. The most inferior transfer factors were measured for the respective seed or fruits. The soil to plant transfer factors of actinides are more dependend on the age of the plants within one growing period. At the beginning of the period, the transfer factor is considerably higher than at the end of this period. With respect to plants with a growing period of several years, correlations are unknown. (orig.)
5. The treatment of liquid radioactive waste containing Americium by using a cation exchange method
International Nuclear Information System (INIS)
A research in the treatment of a liquid radioactive waste containing americium has been done. The liquid radioactive waste used in this research was standard solution of U dan Ce with the initial activity of 100 ppm. The experimental investigation is aimed at a study of the effects of the waste pH, the column dimension of IR-120 cation exchanger which is expressed as L/D, the flow rate of a liquid waste and the influence of thiocyanate as a complex agent against the efficiency of a decontamination for uranium and cerium element. The experiment was done by passing downward the feed of uranium and cerium solution into an IR-120 type of cation exchanger with the L/D of 11.37. From the experimental parameters done in this research where the influence of waste pH was varied from 3 - 8, the geometric column (L/D) 11.37, the liquid flow rate was from 2.5 - 10 ml/m and the thiocyanate concentration was between 100 ppm-500 ppm can be concluded that the optimum operational condition for the ion exchange achieved were the waste pH for uranium = 4 and the waste pH for cerium = 6, the flow rate = 2.5 ml/men. From the given maximum value of DF for uranium = 24 (DE = 95.83%) and of DF for cerium = 40 (DE = 97.5%), it can also be concluded that this investigation is to be continued in order that the greater value of DF/DE can be achieved
6. Transient neuromyopathy after bromide intoxication in a dog with idiopathic epilepsy
Directory of Open Access Journals (Sweden)
Steinmetz Sonja
2012-12-01
Full Text Available Abstract A seven-year old Australian Shepherd, suffering from idiopathic epilepsy under treatment with phenobarbitone and potassium bromide, was presented with generalised lower motor neuron signs. Electrophysiology and muscle-nerve biopsies revealed a neuromyopathy. The serum bromide concentration was increased more than two-fold above the upper reference value. Clinical signs disappeared after applying diuretics and reducing the potassium bromide dose rate. This is the first case report describing electrophysiological and histopathological findings associated with bromide induced lower motor neuron dysfunction in a dog.
7. Use of radioisotopes in the study of tetracycline analytical application. Extraction of compounds formed between tetracycline and neptunium and americium elements
International Nuclear Information System (INIS)
The behavior of tetracycline as complexing agent, in solvent extraction studies of neptunium and americium, using benzyl alcohol as the organic phase, is presented. By using radioactive tracers of 239Np and 241Am the extraction percent of these elements were determined as a function of pH in the absence and in the presence of several masking agents. The influence of shaking time and the use of different types of supporting eletrolytes upon the extraction behavior was also studied. The extraction curves obtained using EDTA as masking agent show that tetracycline can be used for neptunium and americium separation. In this condition neptunium is extracted into the organic phase and americium remains in the aqueous phase. (Author)
8. The in vitro and in vivo profile of aclidinium bromide in comparison with glycopyrronium bromide.
Science.gov (United States)
Gavaldà, Amadeu; Ramos, Israel; Carcasona, Carla; Calama, Elena; Otal, Raquel; Montero, José Luis; Sentellas, Sonia; Aparici, Monica; Vilella, Dolors; Alberti, Joan; Beleta, Jorge; Miralpeix, Montserrat
2014-08-01
This study characterised the in vitro and in vivo profiles of two novel long-acting muscarinic antagonists, aclidinium bromide and glycopyrronium bromide, using tiotropium bromide and ipratropium bromide as comparators. All four antagonists had high affinity for the five muscarinic receptor sub-types (M1-M5); aclidinium had comparable affinity to tiotropium but higher affinity than glycopyrronium and ipratropium for all receptors. Glycopyrronium dissociated faster from recombinant M3 receptors than aclidinium and tiotropium but more slowly than ipratropium; all four compounds dissociated more rapidly from M2 receptors than from M3 receptors. In vitro, aclidinium, glycopyrronium and tiotropium had a long duration of action at native M3 receptors (>8 h versus 42 min for ipratropium). In vivo, all compounds were equi-potent at reversing acetylcholine-induced bronchoconstriction. Aclidinium, glycopyrronium and ipratropium had a faster onset of bronchodilator action than tiotropium. Aclidinium had a longer duration of action than glycopyronnium (time to 50% recovery of effect [t½ offset] = 29 h and 13 h, respectively); these compare with a t½ offset of 64 h and 8 h for tiotropium and ipratropium, respectively. Aclidinium was less potent than glycopyrronium and tiotropium at inhibiting salivation in conscious rats (dose required to produce half-maximal effect [ED50] = 38, 0.74 and 0.88 μg/kg, respectively) and was more rapidly hydrolysed in rat, guinea pig and human plasma compared with glycopyrronium or tiotropium. These results indicate that while aclidinium and glycopyrronium are both potent antagonists at muscarinic receptors with similar kinetic selectivity for M3 receptors versus M2, aclidinium has a longer dissociation half-life at M3 receptors and a longer duration of bronchodilator action in vivo than glycopyrronium. The rapid plasma hydrolysis of aclidinium, coupled to its kinetic selectivity, may confer a reduced propensity for systemic
9. Bromoform formation in ozonated groundwater containing bromide and humic substances
Energy Technology Data Exchange (ETDEWEB)
Cooper, W.J.; Amy, G.L.; Moore, C.A.; Zika, R.G.
1986-01-01
The effect of bromide ion, organic carbon concentration (natural aquatic humic substances), pH, and solar irradiation on the formation of bromoform in ozonated groundwater has been studied. The studies were conducted on four unique samples of groundwater taken from different regions of the Biscayne Aquifer in southern Florida. All other conditions being equal, increases in bromide ion concentrations resulted in increases in CHBr/sub 3/ formation. In three of the four samples, CHBr/sub 3/ formation decreased as the pH level increased from 5 to 9. The fourth sample exhibited an opposite trend whereby the CHBr/sub 3/ concentration increased with increasing pH. Bromoform concentration increased with increased O/sub 3/ concentration over an ozone dosage range of 3.4 to 6.7 mg/L. Ozonated samples placed in sunlight immediately after ozone addition showed a decrease in the formation of CHBr/sub 3/ presumably due to the photodecomposition of HOBr/OBr.
10. Bromoform formation in ozonated groundwater containing bromide and humic substances
Energy Technology Data Exchange (ETDEWEB)
Copper, W.J. (Florida International Univ., Miami (United States)); Amy, G.L. (Univ. of Arizona, Tucson (United States)); Moore, C.A.; Zika, R.G. (Univ. of Miami, FL (United States))
The effect of bromide ion, organic carbon concentration (natural aquatic humic substances), pH, and solar irradiation on the formation of bromoform in ozonated groundwater has been studied. The studies were conducted on four unique samples of groundwater taken from different regions of the Biscayne Aquifer in southern Florida. All other conditions being equal, increases in bromide ion concentrations resulted in increases in CHBr{sub 3} formation. In three of the four samples, CHBr{sub 3} formation decreased as the pH level increased from 5 to 9. The fourth sample exhibited an opposite trend whereby the CHBr{sub 3} concentration increased with increasing pH. Bromoform concentration increased with increased O{sub 3} concentration over an ozone dosage range of 3.4 to 6.7 mg/L. Ozonated samples placed in sunlight immediately after ozone addition showed a decrease in the formation of CHBr{sub 3}, presumably due to the photodecomposition of HOBr/OBr.
11. Synthesis and Characterization of Mercuric Bromide-Phenothiazine Complexes
Directory of Open Access Journals (Sweden)
Vidisha A. Alwani
2014-12-01
Full Text Available N-alkylphenothiazines (NAPTZs are biologically active heterocyclic compounds that find extensive applications in the field of medicine. In the pharmaceutical industry, they are used as psychotherapeutic, antiemetic, and antihistaminic drugs. In this study, complexation reactions of mercuric bromide with NAPTZs as principal ligands have been investigated in MeOH medium. Five mercuric bromide complexes of the NAPTZ ligands namely, chlorpromazine hydrochloride (CP.HCl, promethazine hydrochloride (PM.HCl, ethopropazine hydrochloride (EP.HCl, trifluoperazine dihydrochloride (TF.2HCl and thioridazine hydrochloride (TR.HCl have been synthesized. These complexes were subjected to elemental analysis, solubility, molar conductance and magnetic susceptibility, U.V-Vis, I.R, and NMR spectroscopy. The molecular formulations of the complexes have been found to be: [HgBr2(CP2].4H2O; [HgBr2(PM2].2H2O; [HgBr2(EP2]; [HgBr2(TF2].2H2O and [HgBr2(TR2]. Tentative molecular structures have been proposed and presented.
12. Modeling water/lithium bromide absorption chillers in ASPEN Plus
International Nuclear Information System (INIS)
Highlights: → Single- and double-effect water/lithium bromide absorption chiller designs are numerically modeled using ASPEN. → The modeling procedure is described and the results are compared to published modeling data to access prediction accuracy. → Predictions for the single- and double-effect designs are within 3% and 5%, respectively of published data for all cycle parameters of interest. → The absorption cycle models presented allow investigation of using absorption chillers for waste heat utilization in the oil and gas industry. -- Abstract: Absorption chillers are a viable option for providing waste heat-powered cooling or refrigeration in oil and gas processing plants, thereby improving energy efficiency. In this paper, single- and double-effect water/lithium bromide absorption chiller designs are numerically modeled using ASPEN. The modeling procedure is described and the results are compared to published modeling data to access prediction accuracy. Predictions for the single- and double-effect designs are within 3% and 5%, respectively of published data for all cycle parameters of interest. The absorption cycle models presented not only allow investigation into the benefits of using absorption chillers for waste heat utilization in the oil and gas industry, but are also generically applicable to a wide range of other applications.
13. Development of copper bromide laser master oscillator power amplifier system
G N Tiwari; R K Mishra; R Khare; S V Nakhe
2014-02-01
Development of master oscillator power amplifier (MOPA) system of copper bromide laser (CBL) operating at 110 W average power is reported. The spectral distribution of power at green (510.6 nm) and yellow (578.2 nm) components in the output of a copper bromide laser is studied as a function of operating parameters. The electrical input power was varied from 2.6 to 4.3 kW, the pulse repetition frequency (PRF) was changed from 16 to 19 kHz, and the pressure of the buffer gas (neon) was kept fixed at 20 mbar. When the electrical input power was increased to 4.3 kW from 2.6 kW, the tube-wall temperature also increased to 488°C from 426°C but the ratio of the green to yellow power decreased to 1.53 from 3.73. The ratio of green to yellow power decreased to 1.53 from 1.63 when the PRF of the laser was increased to 19 kHz from 16 kHz. These observations are explained in terms of electron temperature, energy levels of transitions, and voltage and current waveforms across the laser head.
14. Effect of a long-term release of plutonium and americium into an estuarine and coastal sea ecosystem
International Nuclear Information System (INIS)
This paper discusses the general problem of speciation of plutonium and americium in aquatic ecosystems and the implications relative to their fate in those systems. The following conclusions were reached: several oxidation states of plutonium coexist in the natural environment; the effect of environmental changes such as pH and Esub(h) values and complexes are probably the cause of these various oxidation states; a clearer definition of the 'concentration factor' should be given in view of the important role the sediments play in supplying plutonium for transfer through the food web. (author)
15. EFFECT OF COMPOSITION OF SELECTED GROUNDWATERS FROM THE BASIN AND RANGE PROVINCE ON PLUTONIUM, NEPTUNIUM, AND AMERICIUM SPECIATION.
Science.gov (United States)
Rees, Terry F.; Cleveland, Jess M.; Nash, Kenneth L.
1984-01-01
The speciation of plutonium, neptunium, and americium was determined in groundwaters from four sources in the Basin and Range Province: the lower carbonate aquifer, Nevada Test Site (NTS) (Crystal Pool); alluvial fill, Frenchman Flat, NTS (well 5C); Hualapai Valley, Arizona (Red Lake south well); and Tularosa Basin, New Mexico (Rentfrow well). The results were interpreted to indicate that plutonium and, to a lesser extent, neptunium are least soluble in reducing groundwaters containing a large concentration of sulfate ion and a small concentration of strongly complexing anions. The results further emphasize the desirability of including studies such as this among the other site-selection criteria for nuclear waste repositories.
16. Microstructure and elemental distribution of americium-containing MOX fuel under the short-term irradiation tests
International Nuclear Information System (INIS)
In order to investigate the effect of americium addition to MOX fuels on the irradiation behavior, the 'Am-1' program is being conducted in JAEA. The Am-1 program consists of two short-term irradiation tests of 10-minute and 24-hour irradiations and a steady-state irradiation test. The short-term irradiation tests were successfully completed and the post irradiation examinations (PIEs) are in progress. The PIEs for Am-containing MOX fuels focused on the microstructural evolution and redistribution behavior of Am at the initial stage of irradiation and the results to date are reported. (author)
17. Development of a methodology for the determination of americium and thorium by ICP-AES and their inter-element effect
International Nuclear Information System (INIS)
Due to the scarcity of good quality uranium resources, the growth of nuclear technology in India is dependent on the utilization of the vast thorium resources. Therefore, Advance Heavy Water Reactor is going to acquire significant role in the scenario of Indian nuclear technology, where (Th, Pu)O2 will be utilized as fuel in the outermost ring of the reactor core. This will lead to a complex matrix containing thorium as well as americium, which is formed due to β-decay of plutonium. The amount of americium is dependent on the burn up and the storage time of the Pu based fuels. In the present case, attempt was made to develop a method for the determination of americium as well as thorium by ICP-AES. Two emission lines of americium were identified and calibration curves were established for determination of americium. Though the detection limit of 283.236 nm line (5 ng mL-1) of americium was found to be better than that of 408.930 nm (11 ng mL-1), the former line is significantly interfered by large amount of thorium. Three analytical lines (i.e. 283.242, 283.730 and 401.913 nm) of thorium were identified and calibration curves were established along with their detection limits. It was observed that 283.242 and 401.913 nm line are having similar detection limits (18 and 13 ng mL-1, respectively) which are better than that of 283.730 nm (60 ng mL-1). This can be attributed to the high background of 283.273 nm channel of thorium. The spectral interference study revealed that even small amount of americium has significant contribution on 283.242 nm channel of thorium while the other two channels remain practically unaffected. Considering both these facts, spectral interference and analytical performance (detection limits and sensitivity), it was concluded that 401.913 nm line is the best analytical line out of the three lines for determination of thorium in presence of americium. (author)
18. Vapour pressures, densities, and viscosities of the (water + lithium bromide + potassium acetate) system and (water + lithium bromide + sodium lactate) system
Energy Technology Data Exchange (ETDEWEB)
Lucas, Antonio de [Department of Chemical Engineering, University of Castilla - La Mancha, Avda. de Camilo Jose Cela s/n, 13004 Ciudad Real (Spain); Donate, Marina [Department of Chemical Engineering, University of Castilla - La Mancha, Avda. de Camilo Jose Cela s/n, 13004 Ciudad Real (Spain); Rodriguez, Juan F. [Department of Chemical Engineering, University of Castilla - La Mancha, Avda. de Camilo Jose Cela s/n, 13004 Ciudad Real (Spain)]. E-mail: juan.rromero@uclm.es
2006-02-15
Measurements of thermophysical properties (vapour pressure, density, and viscosity) of the (water + lithium bromide + potassium acetate) system LiBr:CH{sub 3}COOK = 2:1 by mass ratio and the (water + lithium bromide + sodium lactate) system LiBr:CH{sub 3}CH(OH)COONa = 2:1 by mass ratio were measured. The system, a possible new working fluid for absorption heat pump, consists of absorbent (LiBr + CH{sub 3}COOK) or (LiBr + CH{sub 3}CH(OH)COONa) and refrigerant H{sub 2}O. The vapour pressures were measured in the ranges of temperature and absorbent concentration from T = (293.15 to 333.15) K and from mass fraction 0.20 to 0.50, densities and viscosities were measured from T = (293.15 to 323.15) K and from mass fraction 0.20 to 0.40. The experimental data were correlated with an Antoine-type equation. Densities and viscosities were measured in the same range of temperature and absorbent concentration as that of the vapour pressure. Regression equations for densities and viscosities were obtained with a minimum mean square error criterion.
19. Effect of radiolysis on leachability of plutonium and americium from 76-101 glass. [Glass containing 2 mole % plutonium
Energy Technology Data Exchange (ETDEWEB)
Nash, K.L.; Fried, S.; Friedman, A.M.; Susak, N.; Rickert, P.; Sullivan, J.C.; Karim, D.P.; Lam, D.J.
1982-01-01
One aspect of the leachability of actinide-bearing glass which has not been adequately addressed is the effect of radiolysis of the system (glass-water) on the amount of actinides liberated from the glass. In the present study, we have investigated the leaching of plutonium and americium from 76-101 glass samples (containing 2 mole % plutonium) in the presence of a one megaRad/hour gamma-radiation field. The presence of the radiation field was found to increase the leaching rate of both plutonium and americium by a factor of five. Speciation studies of the plutonium in the leachate indicate that the plutonium is present predominantly in the higher oxidation states, Pu(V) and Pu(VI) and that it is significantly associated with colloidal particles. Examination of the glass surfaces with x-ray photoemission spectroscopy, XPS, both before and after leaching was carried out; these studies showed lower surface concentrations of plutonium in the samples of glass leached in the radiation field. 1 figure, 3 tables.
20. Osteosarcoma induction by plutonium-239, americium-241 and neptunium-237 : the problem of deriving risk estimates for man
International Nuclear Information System (INIS)
Spontaneous bone cancer (osteosarcoma) represents only about 0.3% of all human cancers, but is well known to be inducible in humans by internal contamination with radium-226 and radium-224. plutonium-239, americium-241 and neptunium-237 form, or will form, the principal long-lived alpha particle emitting components of high activity waste and burnt-up nuclear fuel elements. These three nuclides deposit extensively in human bone and although, fortunately, no case of a human osteosarcoma induced by any of these nuclides is known, evidence from animal studies suggests that all three are more effective than radium-226 in inducing osteosarcoma. The assumption that the ratio of the risk factors, the number of osteosarcoma expected per 10000 person/animal Gy, for radium-226 and any other bone-seeking alpha-emitter will be independent of animal species has formed the basis of all the important studies of the radiotoxicity of actinide nuclides in experimental animals. The aim of this communication is to review the risk factors which may be calculated from the various animal studies carried out over the last thirty years with plutonium-237, americium-241 and neptunium-237 and to consider the problems which may arise in extrapolating these risk factors to homo sapiens
1. 76 FR 7200 - Methyl Bromide; Notice of Receipt of Requests To Voluntarily Amend Registrations To Terminate...
Science.gov (United States)
2011-02-09
... Professional Products to voluntarily amend methyl bromide product registration 8536-12 to terminate or delete... identity or contact information unless you provide it in the body of your comment. If you send an e- mail... Cardinal Professional Products, and Trical, Inc.) to delete certain uses of methyl bromide...
2. SYNTHESIS AND CATALYTIC PROPERTIES OF HYDROPHOBICALLY MODIFIED POLY(ALKYLMETHYLDIALLYLAMMONIUM BROMIDES)
NARCIS (Netherlands)
YANG, YJ; ENGBERTS, JBFN
1991-01-01
A series of hydrophobically modified homo- and copolymers of the poly(alkylmethyldiallylammonium bromide) type has been prepared by free-radical cyclo(co)polymerization of alkylmethyldiallylammonium bromide monomers in aqueous solution. Depending on the length of the alkyl side chain (varied between
3. Destruction of methyl bromide sorbed to activated carbon by thiosulfate and electrolysis
Science.gov (United States)
Methyl bromide is widely used as a fumigant for post-harvest and quarantine uses at port facilities due to the low treatment times required, but it is vented to the atmosphere after its use. Due to the potential contributions of methyl bromide to stratospheric ozone depletion, technologies for the c...
4. Determination of micro-amount bromide in uranium trioxide by spectrophotometric method
International Nuclear Information System (INIS)
The content of bromide in the production of uranium trioxide is one of the most important control factors, so determining it accurately seems important. When uranium trioxide is dissolved in nitric acid, in the presence of AgNO3 solution, micro-amount bromide can be co- precipitated with AgCl. Bromide can be separated by centrifugation from a large amount of UO22+ and other anions. In the existing of KOH and H2O2, AgCl can be changed into free bromide. By adding ammonium molybdate as catalyst, bromide and excessive KBrO3 can react and produce Br2. In the medium of tert-butanol-ethanol, Br2 can react with basic fuchsine and produce a purple compound which is stable, the bromide content is determined by spectrophotometric method. The results show that it is a highly sensitive method with low detection limit. Its apparent molar absorption coefficient κ' is 1.7 x 104 L/(mol·cm). Its detection limit is 9 μg/L and determination limit is 0.13 mg/L. The linear relationship is in the range of 0.2-1.6 mg/L with a correlation coefficient of 0.997. The relative standard deviation is less than 10% after it is determed six times at the same time. For bromide content of 4.00 and 8.00 μg, the bromide recovery obtained are between 94% and 103%. (authors)
5. Solvent effects in the reaction between piperazine and benzyl bromide
S Ranga Reddy; P Manikyamba
2007-11-01
The reaction between piperazine and benzyl bromide was studied conductometrically and the second order rate constants were computed. These rate constants determined in 12 different protic and aprotic solvents indicate that the rate of the reaction is influenced by electrophilicity (), hydrogen bond donor ability () and dipolarity/polarizability (*) of the solvent. The LSER derived from the statistical analysis indicates that the transition state is more solvated than the reactants due to hydrogen bond donation and polarizability of the solvent while the reactant is more solvated than the transition state due to electrophilicity of the solvent. Study of the reaction in methanol, dimethyl formamide mixtures suggests that the rate is maximum when dipolar interactions between the two solvents are maximum.
6. Mechanism of the Deaquation of Aquopentaaminocobalt(Ⅲ) Bromide
Institute of Scientific and Technical Information of China (English)
MA,Li-Dun(马礼敦); CHENG,Guang-Hui(程广辉); WU,Hong-Xiang(吴宏翔); LIN,Han-Yi(林涵毅); SHEN,Xiao-Liang(沈孝良); SHI,Guo-Shun(施国顺)
2002-01-01
There are two theories, SN1 and SN2, for the mechanism of the deaquation of aquopentaamincobalt(Ⅲ) bromide (AAC-B).Both of the theories are supported by some experimental and calculated data. But there are not any experiments to determine directly the structure of the intermediates at different reaction time. In this paper the structures of the intermediates at different reaction time in deaquation-anation of AACB were de-termined by extended X-ray absorption fine structure (EXAFS)and the reaction process wes studied by the combination of Xray powder diffraction and EXAFS. It was demonstrated that the deaquation-anation of AACB obeys the SN2 theory.
7. Design and Fabrication of Externally heated Copper Bromide Laser
Directory of Open Access Journals (Sweden)
J.P. Dudeja
1993-04-01
Full Text Available An externally-heated, longitudinally-discharged, low-repetition-rate copper bromide laser, was designed and fabricated. The green-coloured wavelength at 5106 A from this laser can be used for underwater ranging and detection of submerged objects. Several new changes in the design of discharge tube, heating technique, buffer-gas-flow sub-system and electrical circuit have been conceived and incorporated advantageously in our system. Various parameters, for example, the type of buffer gas and its flow rate, mixture of gases, temperature of the discharge tube, delay between dissociation and excitation pulses, dissociation and excitation energies, and various resonator configurations are being optimised to get the maximum output power/energy from the laser system.
8. Xanthine Biosensor Based on Didodecyldimethylammonium Bromide Modified Pyrolytic Graphite Electrode
Institute of Scientific and Technical Information of China (English)
TANG,Ji-Lin(唐纪琳); HAN,Xiao-Jun(韩晓军); HUANG,Wei-Min(黄卫民); WANG,Er-Kang(汪尔康)
2002-01-01
The vesicle of didodecyldimethylammonium bromide (DDAB)which contained tetrathiafulvalene (TTF) was mixed with xanthine oxidase, and the mixture was cast on the pyrolytic graphite electrode. The lipid films were used to supply a biological environment resembling biomembrane on the surface of the electrode. TTF was used as a mediator because of its high electron-transfer efficiency. A novel xanthine biosensor based on cast DDAB film was developed. The effects of pH and operating potential were explored for optimum analytical performance by using the amperometric method. The response time of the biosensor was less than 10 s. The detection limit of the biosensor was 3.2 × 10-7 mol/L and the liner range was from 4 × 10-7 mol/L to 2.4 × 10-6 mol/L.
9. Irradiation as an alternative to methyl bromide: the Australian situation
International Nuclear Information System (INIS)
International agreement to phase out the fumigant Methyl bromide (MeBr) will have serious implications for pest and disease control in Australia, particularly grain pest control, quarantine usage on fresh horticultural produce and control of soil pathogens or nematodes. Irradiation is a practical alternative but is not currently approved for use in Australia. Other options are available but none of the viable methods except irradiation have the short application time needed for treatment of grams found to be infested during loading at export. This usage is vital, as Australian grain is exported at very high standards of freedom from insects, assured by Government regulatory requirements. Irradiation is contrasted against other alternatives including heat and cold, especially for fresh horticultural produce. (author)
10. Mechanism of the Deaquation of Aquopentaaminocobalt（Ⅲ）Bromide
Institute of Scientific and Technical Information of China (English)
MA，Li－Dun; CHENG，Guang－Hui; 等
2002-01-01
There are two theories,SN1 and SN2, for the mechanism of the deaquation of aquopentaamincobalt(Ⅲ） bromide(AAC-B). Both of the theories are supported by some experimental and calculated data. But there are not any experiments to determine directly the structure of the intermediates at dififferent reaction time.In this paper the structures of the intermediates at different reaction time in deaquation-anation of AACB were determined by extended X-ray absorption fine structure (EXAFS) and the reaction process was studied by the combination of X-ray powder diffraction and EXAFS.It was demonstrated that the deaquation-anation of AACB obeys the SN2 theory.
11. Experimental Study on Behavior of Americium in Pyrochemical Process of Nitride Fuel Cycle
International Nuclear Information System (INIS)
R and D on the transmutation of long-lived minor actinides (MA) by the accelerator-driven system (ADS) using nitride fuels is underway at JAEA. In regard to reprocessing technology, pyrochemical process has several advantages in case of treating spent fuel with large decay heat and fast neutron emission, and recovering highly enriched N-15. In the pyrochemical reprocessing, plutonium and MA are dissolved in LiCl-KCl eutectic melts and selectively recovered into liquid cadmium (Cd) cathode by molten salt electrorefining. The electrochemical behavior in LiCl-KCl eutectic melts and the subsequent nitride formation behavior of plutonium and MA recovered in liquid Cd cathode are investigated. In this paper, recent results on electrochemical study of americium (Am) on electrolyses of AmN in LiCl-KCl eutectic melts and nitride formation of Am recovered in the liquid Cd cathode are presented. Electrochemical behavior of Am on anodic dissolution of AmN and recovery of Am into a liquid Cd cathode by electrolyses in LiCl-KCl eutectic melts was investigated by transient electrochemical techniques. The formal standard potential of Am(III)/Am(0) obtained with the liquid Cd electrode is more positive than that calculated for the solid metal electrode. The potential shift is considered to be attributed to the lowering of the activity of Am by the formation of the intermetallic compound with Cd. Potentiostatic electrolyses of AmN in LiCl-KCl eutectic melts containing AmCl3 at 773 K were carried out. Nitrogen gas generated by the anodic dissolution of AmN was observed, and the current efficiency was obtained from the ratio of the amount of released nitrogen gas and the passed electric charge to be 20 - 28 %. Am was recovered as Am-Cd alloy in the liquid Cd cathode, in which AmCd6 type phase was identified besides Cd phase. The recovered Am was converted to AmN by the nitridation-distillation combined method, in which the Am-Cd alloy was heated in nitrogen gas stream at 973 K. These
12. Action of pinaverium bromide, a calcium-antagonist, on gastrointestinal motility disorders.
Science.gov (United States)
Christen, M O
1990-01-01
1. The evidence reviewed here indicates that pinaverium bromide (Dicetel) relaxes gastrointestinal (GI) structures primarily by inhibiting Ca2+ influx through potential-dependent channels of surface membranes of smooth muscle cells. 2. The in vivo selectivity of pinaverium bromide for the GI tract appears to be due mainly to its pharmacokinetic properties. Because of its low absorption (typical for quaternary ammonium compounds) and marked hepatobiliary excretion, most of the orally-administered dose of pinaverium bromide remains in the GI tract. 3. Orally-administered pinaverium bromide does not elicit adverse cardiovascular side-effects at doses that effectively relieve GI spasm, pain, transit disturbances and other symptoms related to motility disorders. 4. Pinaverium bromide is the only Ca2(+)-antagonist with known therapeutic efficacy in the treatment of irritable bowel syndrome and certain other functional intestinal disorders. PMID:2177709
13. LIBS Spectral Data for a Mixed Actinide Fuel Pellet Containing Uranium, Plutonium, Neptunium and Americium
Energy Technology Data Exchange (ETDEWEB)
Judge, Elizabeth J. [Los Alamos National Laboratory; Berg, John M. [Los Alamos National Laboratory; Le, Loan A. [Los Alamos National Laboratory; Lopez, Leon N. [Los Alamos National Laboratory; Barefield, James E. [Los Alamos National Laboratory
2012-06-18
Laser-induced breakdown spectroscopy (LIBS) was used to analyze a mixed actinide fuel pellet containing 75% UO{sub 2}/20% PuO{sub 2}/3% AmO{sub 2}/2% NpO{sub 2}. The preliminary data shown here is the first report of LIBS analysis of a mixed actinide fuel pellet, to the authors knowledge. The LIBS spectral data was acquired in a plutonium facility at Los Alamos National Laboratory where the sample was contained within a glove box. The initial installation of the glove box was not intended for complete ultraviolet (UV), visible (VIS) and near infrared (NIR) transmission, therefore the LIBS spectrum is truncated in the UV and NIR regions due to the optical transmission of the window port and filters that were installed. The optical collection of the emission from the LIBS plasma will be optimized in the future. However, the preliminary LIBS data acquired is worth reporting due to the uniqueness of the sample and spectral data. The analysis of several actinides in the presence of each other is an important feature of this analysis since traditional methods must chemically separate uranium, plutonium, neptunium, and americium prior to analysis. Due to the historic nature of the sample fuel pellet analyzed, the provided sample composition of 75% UO{sub 2}/20% PuO{sub 2}/3% AmO{sub 2}/2% NpO{sub 2} cannot be confirm without further analytical processing. Uranium, plutonium, and americium emission lines were abundant and easily assigned while neptunium was more difficult to identify. There may be several reasons for this observation, other than knowing the exact sample composition of the fuel pellet. First, the atomic emission wavelength resources for neptunium are limited and such techniques as hollow cathode discharge lamp have different dynamics than the plasma used in LIBS which results in different emission spectra. Secondly, due to the complex sample of four actinide elements, which all have very dense electronic energy levels, there may be reactions and
14. Preconcentration of low levels of americium and plutonium from waste waters by synthetic water-soluble metal-binding polymers with ultrafiltration
International Nuclear Information System (INIS)
A preconcentration approach to assist in the measurement of low levels of americium and plutonium in waste waters has been developed based on the concept of using water-soluble metal-binding polymers in combination with ultrafiltration. The method has been optimized to give over 90% recovery and accountability from actual waste water. (author)
15. Theoretical investigation of pressure-induced structural transitions in americium using GGA+U and hybrid density functional theory methods
DEFF Research Database (Denmark)
Verma, Ashok K.; Modak, P.; Sharma, Surinder M.;
2013-01-01
First-principles calculations have been performed for americium (Am) metal using the generalized gradient approximation + orbital-dependent onsite Coulomb repulsion via Hubbard interaction (GGA+U) and hybrid density functional theory (HYB-DFT) methods to investigate various ground state propertie...
16. Bromine and bromide content in soils: Analytical approach from total reflection X-ray fluorescence spectrometry.
Science.gov (United States)
Gallardo, Helena; Queralt, Ignasi; Tapias, Josefina; Candela, Lucila; Margui, Eva
2016-08-01
Monitoring total bromine and bromide concentrations in soils is significant in many environmental studies. Thus fast analytical methodologies that entail simple sample preparation and low-cost analyses are desired. In the present work, the possibilities and drawbacks of low-power total reflection X-ray fluorescence spectrometry (TXRF) for the determination of total bromine and bromide contents in soils were evaluated. The direct analysis of a solid suspension using 20 mg of fine ground soil (soils (Br content range in soils = 5-40 mg kg(-1)). Information about bromide determination in soils is also possible by analyzing the Br content in water soil extracts. In this case, the TXRF analysis can be directly performed by depositing 10 μL of the internal standardized soil extract sample on a quartz glass reflector in a measuring time of 1500 s. The bromide limit of detection by this approach was 10 μg L(-1). Good agreement was obtained between the TXRF results for the total bromine and bromide determinations in soils and those obtained by other popular analytical techniques, e.g. energy dispersive X-ray fluorescence spectrometry (total bromine) and ionic chromatography (bromide). As a study case, the TXRF method was applied to study bromine accumulation in two agricultural soils fumigated with a methyl bromide pesticide and irrigated with regenerated waste water. PMID:27179429
17. Absorber performance of a water/lithium-bromide absorption chiller
Energy Technology Data Exchange (ETDEWEB)
Xie Guozhen [Beijing University of Civil Engineering and Architecture, Beijing 100044 (China)], E-mail: xieguozhen@bucea.edu.cn; Sheng Guogang [Beijing University of Civil Engineering and Architecture, Beijing 100044 (China); Bansal, Pradeep Kumar [Department of Mechanical Engineering, The University of Auckland, Private Bag 92019 (New Zealand); Li, Guang [Beijing University of Civil Engineering and Architecture, Beijing 100044 (China)
2008-09-15
An absorber is one of the most important components of a lithium-bromide absorption chiller (LBAC) as its absorbing characteristics directly influence the performance of the whole chiller. It has been indicated that the absorbing efficiency and cooling capacity could be improved by increasing the solution concentration. In this paper, based on the mechanism of falling film absorption on horizontal tubes, the theoretical models of falling film absorption on horizontal tubes have been established. A series of programs used for computing the theoretical mathematical models, including simulation of LBAC cycle and falling film absorption, have been programmed. The models have been validated reasonably by the experimental data. The results show that the cooling capacity of the LBAC varies in parabola shape of curve with the solution concentration from 52.5% to 58.5%, and that the best coefficient of performance (COP) occurs at concentration of 57%. The investigation proposes the absorbing process of sub-steady thermodynamic equilibrium for the duality solution under increase absorbing pressure.
18. Absorber performance of a water/lithium-bromide absorption chiller
Energy Technology Data Exchange (ETDEWEB)
Xie, Guozhen; Sheng, Guogang; Li, Guang [Beijing University of Civil Engineering and Architecture, Beijing 100044 (China); Bansal, Pradeep Kumar [Department of Mechanical Engineering, The University of Auckland, Private Bag 92019 (New Zealand)
2008-09-15
An absorber is one of the most important components of a lithium-bromide absorption chiller (LBAC) as its absorbing characteristics directly influence the performance of the whole chiller. It has been indicated that the absorbing efficiency and cooling capacity could be improved by increasing the solution concentration. In this paper, based on the mechanism of falling film absorption on horizontal tubes, the theoretical models of falling film absorption on horizontal tubes have been established. A series of programs used for computing the theoretical mathematical models, including simulation of LBAC cycle and falling film absorption, have been programmed. The models have been validated reasonably by the experimental data. The results show that the cooling capacity of the LBAC varies in parabola shape of curve with the solution concentration from 52.5% to 58.5%, and that the best coefficient of performance (COP) occurs at concentration of 57%. The investigation proposes the absorbing process of sub-steady thermodynamic equilibrium for the duality solution under increase absorbing pressure. (author)
19. Water-lithium bromide double-effect absorption cooling analysis
Energy Technology Data Exchange (ETDEWEB)
Vliet, G.C.; Lawson, M.B.; Lithgow, R.A.
1980-12-01
A numerical model was developed for the transient simulation of the double-effect, water-lithium bromide absorption cooling machine, and the use of the model to determine the effect of the various design and input variables on the absorption unit performance. The performance parameters considered were coefficient of performance and cooling capacity. The sensitivity analysis was performed by selecting a nominal condition and determining performance sensitivity for each variable with others held constant. The variables considered in the study include source hot water, cooling water, and chilled water temperatures; source hot water, cooling water, and chilled water flow rates; solution circulation rate; heat exchanger areas; pressure drop between evaporator and absorber; solution pump characteristics; and refrigerant flow control methods. The performance sensitivity study indicated in particular that the distribution of heat exchanger area among the various (seven) heat exchange components is a very-important design consideration. Moreover, it indicated that the method of flow control of the first effect refrigerant vapor through the second effect is a critical design feature when absorption units operate over a significant range of cooling capacity. The model was used to predict the performance of the Trane absorption unit with fairly good accuracy.
20. Chloride, bromide and iodide scintillators with europium doping
Science.gov (United States)
Zhuravleva, Mariya; Yang, Kan
2014-08-26
A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.
1. 4-Bromophenacyl bromide specifically inhibits rhoptry secretion during Toxoplasma invasion.
Science.gov (United States)
Ravindran, Sandeep; Lodoen, Melissa B; Verhelst, Steven H L; Bogyo, Matthew; Boothroyd, John C
2009-01-01
Toxoplasma gondii is a eukaryotic parasite of the phylum Apicomplexa that is able to infect a wide variety of host cells. During its active invasion process it secretes proteins from discrete secretory organelles: the micronemes, rhoptries and dense granules. Although a number of rhoptry proteins have been shown to be involved in important interactions with the host cell, very little is known about the mechanism of secretion of any Toxoplasma protein into the host cell. We used a chemical inhibitor of phospholipase A2s, 4-bromophenacyl bromide (4-BPB), to look at the role of such lipases in the secretion of Toxoplasma proteins. We found that 4-BPB was a potent inhibitor of rhoptry secretion in Toxoplasma invasion. This drug specifically blocked rhoptry secretion but not microneme secretion, thus effectively showing that the two processes can be de-coupled. It affected parasite motility and invasion, but not attachment or egress. Using propargyl- or azido-derivatives of the drug (so-called click chemistry derivatives) and a series of 4-BPB-resistant mutants, we found that the drug has a very large number of target proteins in the parasite that are involved in at least two key steps: invasion and intracellular growth. This potent compound, the modified "click-chemistry" forms of it, and the resistant mutants should serve as useful tools to further study the processes of Toxoplasma early invasion, in general, and rhoptry secretion, in particular. PMID:19956582
2. Organomontmorillonites Modified with 2-Methacryloyloxy Ethyl Alkyl Dimethyl Ammonium Bromide
Institute of Scientific and Technical Information of China (English)
WANG Jian-quan; WU Wen-hui
2007-01-01
Organomontmorillonites (organo-MMT) were synthesized by means of montmorillonites (MMT) modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide (MAAB) having different alkyl chain lengths as cationic surfactants through a cationic exchanging reaction, and were characterized by FTIR, TG, elemental analysis, and XRD. The microenvironment of the organic interlayer such as the orientation and arrangement of the alkyl chains of MAAB, as well as the properties of nanocomposite hydrogels, were also investigated. The amount of organic components absorbed on interlayer and the basal spacing of organo-MMT both increase with the increasing of alkyl length of MAAB. When carbon number of alkyl chain is in the region of 8 to 14, the alkyl chains between layers would adopt a disordered gauche conformation; while the carbon number is 16, an ordered all-trans conformation with a vertical orientation would be found together with the disordered gauche conformation according to the results of XRD and FTIR. Due to the difference of microenvironment of organic interlayer, the Young's moduli of the nanocomposite hydrogels increased as the alkyl chains of MAAB became longer.
3. Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles
Directory of Open Access Journals (Sweden)
M. Wachsmuth
2002-01-01
Full Text Available Uptake of HOBr on sea salt aerosol, sea salt brine or ice is believed to be a key process providing a source of photolabile bromine (Br2 and sustaining ozone depletion cycles in the Arctic troposphere. In the present study, uptake of HOBr on sodium bromide (NaBr aerosol particles was investigated at an extremely low HOBr concentration of 300 cm-3 using the short-lived radioactive isotopes 83-86Br. Under these conditions, at maximum one HOBr molecule was taken up per particle. The rate of uptake was clearly limited by the mass accommodation coefficient, which was calculated to be 0.6 ± 0.2. This value is a factor of 10 larger than estimates used in earlier models. The atmospheric implications are discussed using the box model "MOCCA'', showing that the increase of the accommodation coefficient of HOBr by a factor of 10 only slightly affects net ozone loss, but significantly increases chlorine release.
4. Bioreactors for removing methyl bromide following contained fumigations
Science.gov (United States)
Miller, L.G.; Baesman, S.M.; Oremland, R.S.
2003-01-01
Use of methyl bromide (MeBr) as a quarantine, commodity, or structural fumigant is under scrutiny because its release to the atmosphere contributes to the depletion of stratospheric ozone. A closed-system bioreactor consisting of 0.5 L of a growing culture of a previously described bacterium, strain IMB-1, removed MeBr (> 110 ??mol L-1) from recirculating air. Strain IMB-1 grew slowly to high cell densities in the bioreactor using MeBr as its sole carbon and energy source. Bacterial oxidation of MeBr produced CO2 and hydrobromic acid (HBr), which required continuous neutralization with NaOH for the system to operate effectively. Strain IMB-1 was capable of sustained oxidation of large amounts of MeBr (170 mmol in 46 d). In an open-system bioreactor (10-L fermenter), strain IMB-1 oxidized a continuous supply of MeBr (220 ??mol L-1 in air). Growth was continuous, and 0.5 mol of MeBr was removed from the air supply in 14 d. The specific rate of MeBr oxidation was 7 ?? 10-16 mol cell-1 h-1. Bioreactors such as these can therefore be used to remove large quantities of contaminant MeBr, which opens the possibility of biodegradation as a practical means for its disposal.
5. Evaluation of Alkali Bromide Salts for Potential Pyrochemical Applications
Energy Technology Data Exchange (ETDEWEB)
Prabhat K. Tripathy; Steven D. Herrmann; Guy L. Fredrickson; Tedd E. Lister; Toni Y. Gutknecht
2013-10-01
Transient techniques were employed to study the electrochemical behavior, reduction mechanism and transport properties of REBr3 (RE - La, Nd and Gd) in pure LiBr, LiBr-KBr (eutectic) and LiBr-KBr-CsBr (eutectic) melts. Gd(III) showed a reversible single step soluble-insoluble exchange phenomenon in LiBr melt at 973K. Although La (III), Nd(III) and Gd(III) ions showed reversible behavior in eutectic LiBr-KBr melts, these ions showed a combination of temperature dependent reversible and pseudo-reversible behavior. While both La(III) and Gd(III) showed one step reduction, the reduction of Nd(III) was observed to be a two step process. La metal could be electrodeposited from the ternary electrolyte at a temperature of 673K. Various electrochemical measurements suggest that both binary and ternary bromide melts can potentially be used to electrodeposit high purity RE metals at comparatively lower operating temperatures.
6. A comparison of the effect of intranasal desmopressin and intramuscular hyoscine N-butyl bromide combination with intramuscular hyoscine N-butyl bromide alone in acute renal colic
Directory of Open Access Journals (Sweden)
Abdol-Reza Kheirollahi
2010-01-01
Full Text Available Background: Patients with acute renal colic usually require immediate diagnosis and treatment. In this clinical trial analgesic effect of hyoscine N-butyl bromide and desmopressin combination in comparison with hyoscine N-butyl bromide alone in patients with acute renal colic induced by urinary stones was assessed. Methods: The study included 114 patients randomly allocated in two groups (A and B. Patients in group A received 20 mg intramuscular hyoscine N-butyl bromide at admission time and patients in group B received 20 μg of intranasal desmopressin in combination with 20 mg intramuscular hyoscine N-butyl bromide. A visual analogue scale (VAS; a 10-cm horizontal scale ranging from "zero or no pain" to "10 or unbearable pain" was hired to assess the patients′ pain severity at baseline, 30 and 60 minutes after the treatments. Results: On admission, the pain level was similar in both groups (group A: 8.95 ± 0.11 and group B: 8.95 ± 0.12. In group A, the mean of pain level showed a decrease after 30 minutes (group A: 7.26 ± 0.25 and group B: 5.95 ± 0.28 but further decreasing did not occur; however in group B, the pain consistently decreased and the mean after 60 minutes was significantly decreased (group A: 6.80 ± 0.31 and group B: 3.71 ± 0.31. No side effects were detected in this study. Conclusions: The combination of hyoscine N-butyl bromide and desmopressin is more effective than hyoscine N-butyl bromide alone in patients with renal colic. Further studies are recommended to validate these findings and compare the different doses of desmopressin.
7. Plasmid DNA induces dodecyl triethyl ammonium bromide to aggregate into vesicle
Institute of Scientific and Technical Information of China (English)
Xiang Mei Ran; Xia Guo; Jia Tong Ding
2012-01-01
Single-chained cationic surfactant dodecyl triethyl ammonium bromide and plasmid DNA together can form vesicles once the concentration of plasmid DNA reaches a critical value (Ccvc).Bigger the size of plasmid DNA,higher the value of Ccvc.
8. Corrosion Behavior of Austenitic and Duplex Stainless Steels in Lithium Bromide
OpenAIRE
Ayo Samuel AFOLABI; Alaneme, K.K.; Samson Oluwaseyi BADA
2009-01-01
The corrosion behavior of austenitic and duplex stainless steels in various concentrations of lithium, bromide solution was investigated by using the conventional weight loss measurement method. The results obtained show that corrosion of these steels occurred due to the aggressive bromide ion in the medium. Duplex stainless steel shows a greater resistance to corrosion than austenitic stainless steel in the medium. This was attributed to equal volume proportion of ferrite and austenite in th...
9. A case report of QT prolongation with glycopyrronium bromide in a patient with chronic tamoxifen use
OpenAIRE
Chiu, Michael H.; Al-Majed, Nawaf S.; Stubbins, Ryan; Pollmann, Dylan; Sandhu, Roopinder K.
2016-01-01
Background Glycopyrronium bromide has recently been approved as a once daily maintenance inhalation therapy for moderate to severe chronic obstructive pulmonary disease (COPD). Efficacy and safety trial data have found rare cases of significant QT prolongation. To our knowledge, we describe the first case report of QT prolongation >600 ms with initiation of glycopyrronium bromide in a real world setting. Case presentation A 78-year-old female with moderate COPD recently started on glycopyrron...
10. Influence of bromide on the performance of the amphipod Hyalella azteca in reconstituted waters
Science.gov (United States)
Ivey, Chris D.; Ingersoll, Christopher G.
2016-01-01
Poor performance of the amphipod Hyalella azteca has been observed in exposures using reconstituted waters. Previous studies have reported success in H. azteca water-only exposures with the addition of relatively high concentrations of bromide. The present study evaluated the influence of lower environmentally representative concentrations of bromide on the response ofH. azteca in 42-d water-only exposures. Improved performance of H. azteca was observed in reconstituted waters with >0.02 mg Br/L.
11. The effect of pinaverium bromide (LA 1717) on the lower oesophageal sphincter.
Science.gov (United States)
Wöltje, M; Huchzermeyer, H
1982-01-01
An acute, double-blind study was carried out in 8 healthy male volunteers to investigate any effect of a new antispasmodic, pinaverium bromide, compared with placebo on the lower oesophageal sphincter. Manometric measurements showed no significant differences in resting pressures either after placebo or a therapeutic dose (200 mg) of pinaverium bromide, suggesting that the active drug does not cause any impairment of function of the lower oesophageal sphincter. PMID:7128186
12. Inhibition of methoxamine-induced bronchoconstriction by ipratropium bromide and disodium cromoglycate in asthmatic subjects.
OpenAIRE
Black, J.; Vincenc, K; Salome, C.
1985-01-01
We compared the effects of pretreatment with saline, ipratropium bromide, and disodium cromoglycate (DSCG) on bronchoconstriction induced by methoxamine--an alpha-adrenoceptor agonist, in asthmatic subjects. All 12 patients bronchoconstricted in response to methoxamine after saline. The PD20 (the dose of methoxamine causing a 20% fall in forced expiratory volume in 1 s [FEV1]) ranged from 0.3-18 mumol. Ipratropium bromide (200 micrograms administered by aerosol) significantly inhibited (P les...
13. Tribromoisocyanuric acid/triphenylphosphine: a new system for conversion of alcohols into alkyl bromides
Energy Technology Data Exchange (ETDEWEB)
Andrade, Vitor S.C. de; Mattos, Marcio C.S. de, E-mail: mmattos@iq.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Instituto de Quimica. Departamento de Quimica Organica
2014-05-15
An efficient and facile method has been developed for the conversion of alcohols into alkyl bromides under neutral conditions using tribromoisocyanuric acid and triphenylphosphine (molar ratio 1.0:0.7:2.0, alcohol/tribromoisocyanuric acid/triphenylphosphine) in dichloromethane at room temperature. This method can be applied for the conversion of primary, secondary, benzilic and allylic alcohols, and their corresponding bromides are obtained in 67-82 % yield. Tertiary alcohols do not react under these conditions. (author)
14. Electrochemical Recognition of Metalloproteins by Bromide-modified Silver Electrode - A New Method
Directory of Open Access Journals (Sweden)
Abbas Ali Rostami
2007-07-01
Full Text Available A bromide–modified silver electrode is reported, in the present study, to catalyzethe redox reactions of metalloproteins. This study describes that the bromide ions showvery good redox behavior with silver electrode. The cathodic and anodic peak potentialswere related to the concentration of bromide ions involved in making bromide-modifiedsilver electrode. The electrode reaction in the bromine solution was a diffusion-controlledprocess. Positive potential shift of the bromide ions was seen when different proteins wereadded to the solution using a silver electrode. New cathodic and anodic peaks wereobserved at different potential ranges for myoglobin, cytochrome c and catalase. A linearlyincreasing cathodic peak current of bromide ions was seen when the concentration ofsuperoxide dismutase was increased in the test solution. However, no change for albuminwas observed when its concentration was increased in the test solution. Present data provesour methodology as an easy-to-use analysis for comparing the redox potentials of differentmetalloproteins and differentiating the metallo- from non-metalloproteins. In this study, weintroduced an interesting method for bio-electrochemical analyses.
15. Effect of ferric and bromide ions on the formation and speciation of disinfection byproducts during chlorination
Institute of Scientific and Technical Information of China (English)
Shaogang Liu; Zhiliang Zhu; Yanling Qiu; Jianfu Zhao
2011-01-01
The effects of ferric ion, pH, and bromide on the formation and distribution of disinfection byproducts (DBPs) during chlorination were studied. Two raw water samples from Huangpu River and Yangtze River, two typical drinking water sources of Shanghai, were used for the investigation. Compared with the samples from Huangpu River, the raw water samples from Yangtze River had lower content of total organic carbon (TOC) and ferric ions, but higher bromide concentrations. Under controlled chlorination conditions,four trihalomethanes (THMs), nine haloacetic acids (HAAs), total organic halogen (TOX) and its halogen species fractions, including total organic chlorine (TOC1) and total organic bromide (TOBr), were determined. The results showed that co-existent ferric and bromide ions significantly promoted the formation of total THMs and HAAs for both raw water samples. Higher concentration of bromide ions significantly changed the speciation of the formed THMs and HAAs. There was an obvious shift to brominated species,which might result in a more adverse influence on the safety of drinking water. The results also indicated that high levels of bromide ions in raw water samples produced higher percentages of unknown TOBr.
16. Effect of ferric and bromide ions on the formation and speciation of disinfection byproducts during chlorination.
Science.gov (United States)
Liu, Shaogang; Zhu, Zhiliang; Qiu, Yanling; Zhao, Jianfu
2011-01-01
The effects of ferric ion, pH, and bromide on the formation and distribution of disinfection byproducts (DBPs) during chlorination were studied. Two raw water samples from Huangpu River and Yangtze River, two typical drinking water sources of Shanghai, were used for the investigation. Compared with the samples from Huangpu River, the raw water samples from Yangtze River had lower content of total organic carbon (TOC) and ferric ions, but higher bromide concentrations. Under controlled chlorination conditions, four trihalomethanes (THMs), nine haloacetic acids (HAAs), total organic halogen (TOX) and its halogen species fractions, including total organic chlorine (TOC1) and total organic bromide (TOBr), were determined. The results showed that co-existent ferric and bromide ions significantly promoted the formation of total THMs and HAAs for both raw water samples. Higher concentration of bromide ions significantly changed the speciation of the formed THMs and HAAs. There was an obvious shift to brominated species, which might result in a more adverse influence on the safety of drinking water. The results also indicated that high levels of bromide ions in raw water samples produced higher percentages of unknown TOBr.
17. Predicting bromide incorporation in a chlorinated indoor swimming pool.
Science.gov (United States)
Chowdhury, Shakhawat; Mazumder, Abu Jafar; Husain, Tahir
2016-06-01
The water in and air above swimming pools often contain high levels of disinfection byproducts (DBPs) due to chemical reactions between chlorine- or bromine-based disinfectants and organic/inorganic matter in the source water and released from swimmers. Exposure to these DBPs, though inevitable, can pose health threats to humans. In this study, DBPs in tap water (S1), and water from a chlorinated indoor swimming pool before (S2) and after swimming (S3) were measured. The brominated species constituted the majority of DBPs formed in S1, S2, and S3. Trihalomethanes (THMs) in S3 was 6.9 (range 2.9-11.1) and 1.4 (range 0.52-2.9) times those in S1 and S2, respectively; and the haloacetic acids (HAAs) in S3 was 4.2 (range 2.5-7.5) and 1.2 (range 0.6-2.6) times those in S1 and S2, respectively. The mean THMs in air above the swimming pool before (S2-A) and after swimming (S3-A) were 72.2 and 93.0 μg/m(3), respectively, and their ranges were 36.3-105.8 and 44.1-133.6 μg/m(3), respectively. The average percentages of bromide incorporation (BI) into THMs in S1, S2, and S3 were 3.0, 9.3, and 10.6 %, respectively; and the BI into HAAs in S1, S2, and S3 were 6.6, 12.0, and 12.2 %, respectively. Several models were trained for predicting the BI into THMs and HAAs. The results indicate that additional information is required to develop predictive models for BI in swimming pools.
18. Bacterial oxidation of methyl bromide in fumigated agricultural soils
Science.gov (United States)
Miller, L.G.; Connell, T.L.; Guidetti, J.R.; Oremland, R.S.
1997-01-01
The oxidation of [14C]methyl bromide ([14C]MeBr) to 14CO2 was measured in field experiments with soils collected from two strawberry plots fumigated with mixtures of MeBr and chloropicrin (CCI3NO2). Although these fumigants are considered potent biocides, we found that the highest rates of MeBr oxidation occurred 1 to 2 days after injection when the fields were tarped, rather than before or several days after injection. No oxidation of MeBr occurred in heat-killed soils, indicating that microbes were the causative agents of the oxidation. Degradation of MeBr by chemical and/or biological processes accounted for 20 to 50% of the loss of MeBr during fumigation, with evasion to the atmosphere inferred to comprise the remainder. In laboratory incubations, complete removal of [14C]MeBr occurred within a few days, with 47 to 67% of the added MeBr oxidized to 14CO2 and the remainder of counts associated with the solid phase. Chloropicrin inhibited the oxidation of MeBr, implying that use of this substance constrains the extent of microbial degradation of MeBr during fumigation. Oxidation was by direct bacterial attack of MeBr and not of methanol, a product of the chemical hydrolysis of MeBr. Neither nitrifying nor methane-oxidizing bacteria were sufficiently active in these soils to account for the observed oxidation of MeBr, nor could the microbial degradation of MeBr be linked to cooxidation with exogenously supplied electron donors. However, repeated addition of MeBr to live soils resulted in higher rates of its removal, suggesting that soil bacteria used MeBr as an electron donor for growth. To support this interpretation, we isolated a gram-negative, aerobic bacterium from these soils which grew with MeBr as a sole source of carbon and energy.
19. The killing of African trypanosomes by ethidium bromide.
Directory of Open Access Journals (Sweden)
Arnab Roy Chowdhury
Full Text Available Introduced in the 1950s, ethidium bromide (EB is still used as an anti-trypanosomal drug for African cattle although its mechanism of killing has been unclear and controversial. EB has long been known to cause loss of the mitochondrial genome, named kinetoplast DNA (kDNA, a giant network of interlocked minicircles and maxicircles. However, the existence of viable parasites lacking kDNA (dyskinetoplastic led many to think that kDNA loss could not be the mechanism of killing. When recent studies indicated that kDNA is indeed essential in bloodstream trypanosomes and that dyskinetoplastic cells survive only if they have a compensating mutation in the nuclear genome, we investigated the effect of EB on kDNA and its replication. We here report some remarkable effects of EB. Using EM and other techniques, we found that binding of EB to network minicircles is low, probably because of their association with proteins that prevent helix unwinding. In contrast, covalently-closed minicircles that had been released from the network for replication bind EB extensively, causing them, after isolation, to become highly supertwisted and to develop regions of left-handed Z-DNA (without EB, these circles are fully relaxed. In vivo, EB causes helix distortion of free minicircles, preventing replication initiation and resulting in kDNA loss and cell death. Unexpectedly, EB also kills dyskinetoplastic trypanosomes, lacking kDNA, by inhibiting nuclear replication. Since the effect on kDNA occurs at a >10-fold lower EB concentration than that on nuclear DNA, we conclude that minicircle replication initiation is likely EB's most vulnerable target, but the effect on nuclear replication may also contribute to cell killing.
20. Eudragit RS PO nanoparticles for sustained release of pyridostigmine bromide
International Nuclear Information System (INIS)
Pyridostigmine bromide (PB) is an inhibitor of cholinesterase, which is used in the treatment of myasthenia gravis and administered for protection against exposure to toxic nerve agents. Tests were done to investigate prolonging the half-life of PB and improving its release behavior. PB was loaded in nanoparticles (NPs) of Eudragit RS PO (Eu-RS) prepared using the technique of quasi emulsion solvent diffusion. Variables of output power of the sonicator, bath temperature and mixing time, were chosen as the optimization factors to obtain the minimum sized NPs. In addition, emulsions were tested at different ratios of drug-to-polymer by dynamic light scattering to determine size and zeta potential of NPs. UV-spectroscopy was used to determine PB content of the NPs. Drug-loaded NPs were characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectra. Results determined that mixing time had a significant impact on the size of Eu-RS NPs, but power output of sonicator and bath temperature had no significant effect. The particle size obtained at the optimum condition (power output of 70 W, bath temperature of 33 °C, and mixing time of 7 min) was less than 200 nm (optimum sizes were 138.9 and 179.5 nm for Eu-RS and PB-loaded Eu-RS NPs, respectively). The optimum PB-loaded Eu-RS NPs at the PB to Eu-RS weight ratio of 1–4 and 20 % of loaded PB released from the nanocarriers within 100 h
1. Silica nanoparticles separation from water: aggregation by cetyltrimethylammonium bromide (CTAB).
Science.gov (United States)
Liu, Y; Tourbin, M; Lachaize, S; Guiraud, P
2013-07-01
Nanoparticles will inevitably be found in industrial and domestic wastes in the near future and as a consequence soon in water resources. Due to their ultra-small size, nanoparticles may not only have new hazards for environment and human health, but also cause low separation efficiency by classical water treatments processes. Thus, it would be an important challenge to develop a specific treatment with suitable additives for recovery of nanoparticles from waters. For this propose, this paper presents aggregation of silica nanoparticles (Klebosol 30R50 (75nm) and 30R25 (30nm)) by cationic surfactant cetyltrimethylammonium bromide (CTAB). Different mechanisms such as charge neutralization, "depletion flocculation" or "volume-restriction", and "hydrophobic effect" between hydrocarbon tails of CTAB have been proposed to explicate aggregation results. One important finding is that for different volume concentrations between 0.05% and 0.51% of 30R50 suspensions, the same critical coagulation concentration was observed at CTAB=0.1mM, suggesting the optimized quantity of CTAB during the separation process for nanoparticles of about 75nm. Furthermore, very small quantities of CTAB (0.01mM) can make 30R25 nanosilica aggregated due to the "hydrophobic effect". It is then possible to minimize the sludge and allow the separation process as "greener" as possible by studying this case. It has also shown that aggregation mechanisms can be different for very small particles so that a special attention has to be paid to the treatment of nanoparticles contained in water and wastewaters.
2. Stability of penta- and hexavalent americium in the solutions of sodium peroxydisulfate and sodium bromate at intensive internal α-irradiation
International Nuclear Information System (INIS)
The spectrometric method has been used for studying the dependence of the rates of radiolytic reduction of Am(5) and (6) on the initial concentration of sodium persulfate and bromate, Am(5) and (6), acidity, and the dose rate of inner alpha-irradiation of the solutions. The high dose rates of inner alpha-irradiation of solutions (up to 3.25x1021 eV/lxmin-250Ci/l) have been attained with the aid of curium isotopes. The stability of americium (6) ions towards the action of ionizing radiation in solutions of sodium persulfate and bromate has been shown to be considerable lower than that of americium (5). The chemical difference has been shown in radiolytic behaviour between Am(5) and Am(6) ions in solutions of sodium persulfate and bromate. The equations have been derived showing the dependence of the rates of Am(6) and Am(5) reduction of different variables
3. Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium-americium mixed oxides
Science.gov (United States)
Prieur, D.; Lebreton, F.; Martin, P. M.; Caisso, M.; Butzbach, R.; Somers, J.; Delahaye, T.
2015-10-01
Uranium-americium mixed oxides are potential compounds to reduce americium inventory in nuclear waste via a partitioning and transmutation strategy. A thorough assessment of the oxygen-to-metal ratio is paramount in such materials as it determines the important underlying electronic structure and phase relations, affecting both thermal conductivity of the material and its interaction with the cladding and coolant. In 2011, various XAS experiments on U1-xAmxO2±δ samples prepared by different synthesis methods have reported contradictory results on the charge distribution of U and Am. This work alleviates this discrepancy. The XAS results confirm that, independently of the synthesis process, the reductive sintering of U1-xAmxO2±δ leads to the formation of similar fluorite solid solution indicating the presence of Am+III and U+V in equimolar proportions.
4. THE FIRST ISOLATION OF AMERICIUM IN THE FORM OF PURE COMPOUNDS - THE SPECIFIC ALPHA-ACTIVITY AND HALF-LIFE OF Am241
Energy Technology Data Exchange (ETDEWEB)
Cunningham, B.B.; Asprey, L.B.
1950-07-20
The microgram scale isolation and preparation of pure compounds of americium is described. Data are presented to show that the alpha-half-life of the isotope Am{sup 241} is 490 {+-} 14 years. The absorption spectrum of Am(III) in 1M nitric acid in the range 3500-8000 mu is given. The wave lengths of 10 of the most prominent lines in the copper spark emission spectrum of americium are given to the nearest 0.01 {angstrom}. Evidence is presented to show that the potential for the Am(III)-Am(IV) couple in acid solution is more negative than -2v and that the potential for the Am(II)-Am(III) couple is more positive than +0.9v.
5. A Density Functional Study of Atomic Hydrogen and Oxygen Chemisorption on the Relaxed (0001) Surface of Double Hexagonal Close Packed Americium
OpenAIRE
Dholabhai, P. P.; Atta-Fynn, R.; A.K. Ray
2009-01-01
Ab initio total energy calculations within the framework of density functional theory have been performed for atomic hydrogen and oxygen chemisorption on the (0001) surface of double hexagonal packed americium using a full-potential all-electron linearized augmented plane wave plus local orbitals method. Chemisorption energies were optimized with respect to the distance of the adatom from the relaxed surface for three adsorption sites, namely top, bridge, and hollow hcp sites, the adlayer str...
6. Experimental study of Americium-241 biokinetics in Homarus Gammarus lobster. Analysis of the accumulation and detoxication mechanisms at the sub-cellular level
International Nuclear Information System (INIS)
The Americium 241 radioelement accumulation and elimination rate and mechanisms in the lobster organism have been experimentally studied; incorporation and detoxification capacities of each organ are evaluated. The existence of various biological compartments is shown; the major role of the digestive gland in accumulation of the radioelement, its distribution towards the various organs, and its resorption is comprehensively described, with an analysis at the subcellular and molecular levels. 401 p., 65 fig., 43 tab., 428 ref
7. A new method for the determination of plutonium and americium using high pressure microwave digestion and alpha-spectrometry or ICP-SMS
International Nuclear Information System (INIS)
Plutonium and americium are radionuclides particularly difficult to measure in environmental samples because they are a-emitters and therefore necessitate a careful separation before any measurement, either using radiometric methods or ICP-SMS. Recent developments in extraction chromatography resins such as EichromR TRU and TEVA have resolved many of the analytical problems but drawbacks such as low recovery and spectral interferences still occasionally occur. Here, we report on the use of the new EichromR DGA resin in association with TEVA resin and high pressure microwave acid leaching for the sequential determination of plutonium and americium in environmental samples. The method results in average recoveries of 83 ± 15% for plutonium and 73 ± 22% for americium (n = 60), and a less than 10% deviation from reference values of four IAEA reference materials and three samples from intercomparisons exercises. The method is also suitable for measuring 239Pu in water samples at the μBq/l level, if ICP-SMS is used for the measurement. (author)
8. An experimental study of americium-241 biokinetics in the Lobster Homarus Gammarus. Analysis of the accumulation/storage and detoxification processes at the subcellular level
International Nuclear Information System (INIS)
An experimental study of americium-241 kinetics has been conducted in the lobster Homarus gammmarus. The investigations were conducted at all the levels from the whole body to the subcellular and molecular levels. The animals were contaminated by a single or chronic ingestion of 241 Am labelled mussels. Assessments of accumulation, elimination and distribution of the radionuclide were established on organisms kept in the laboratory; they made it possible to demonstrate the importance of the digestive gland in the radionuclide transfer pathways. The preliminary results led to structural then ultrastructural investigations of the digestive gland in association with radioautographic studies and cellular extractions methods. Four cellular types were demonstrated, only two of them being implied in the radionuclide retention, the former being responsible for americium intake and the latter for its long-term retention. By means of biochemical techniques, subcellular accumulation was studied and the organelles implied in the nuclide retention were specified. Finally, a method of cellular nuclei dissociation was developed; it made it possible to analyse the molecular nature of americium ligands and to demonstrate the function of the protein nuclear matrix in the nuclide retention
9. Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium–americium mixed oxides
Energy Technology Data Exchange (ETDEWEB)
Prieur, D., E-mail: dam.prieur@gmail.com [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe (Germany); Lebreton, F. [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze cedex (France); Martin, P.M. [CEA, DEN, DEC/SESC/LLCC, 13108 Saint-Paul-Lez-Durance cedex (France); Caisso, M. [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze cedex (France); Butzbach, R. [Helmholtz Zentrum Dresden Rossendorf (HZDR), Institute of Radiochemistry, P.O. Box 10119, 01314 Dresden (Germany); Somers, J. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe (Germany); Delahaye, T. [CEA, DEN, DTEC/SDTC/LEMA, 30207 Bagnols-sur-Cèze cedex (France)
2015-10-15
Uranium–americium mixed oxides are potential compounds to reduce americium inventory in nuclear waste via a partitioning and transmutation strategy. A thorough assessment of the oxygen-to-metal ratio is paramount in such materials as it determines the important underlying electronic structure and phase relations, affecting both thermal conductivity of the material and its interaction with the cladding and coolant. In 2011, various XAS experiments on U{sub 1−x}Am{sub x}O{sub 2±δ} samples prepared by different synthesis methods have reported contradictory results on the charge distribution of U and Am. This work alleviates this discrepancy. The XAS results confirm that, independently of the synthesis process, the reductive sintering of U{sub 1−x}Am{sub x}O{sub 2±δ} leads to the formation of similar fluorite solid solution indicating the presence of Am{sup +III} and U{sup +V} in equimolar proportions. - Graphical abstract: Formation of (U{sup IV/V},Am{sup III})O{sup 2} solid solution by sol–gel and by powder metallurgy. - Highlights: • Uranium–americium mixed oxides were synthesized by sol–gel and powder metallurgy. • Fluorite solid solutions with similar local environment have been obtained. • U{sup V} and Am{sup III} are formed in equimolar proportions.
10. Chlorine-36, bromide, and the origin of spring water
Science.gov (United States)
Davis, S.N.; Cecil, L.D.; Zreda, M.; Moysey, S.
2001-01-01
Natural ratios of chlorine-36 (36Cl) to stable chlorine (i.e., 36Cl/Cl ?? 10-15) vary in shallow groundwater of the United States from about 50 in coastal areas to about 1400 in the northern Rocky Mountains. Ratios lower than these indicate the presence of chloride (Cl-) that has been isolated from the atmosphere for hundreds of thousands of years, if not longer. Higher ratios, which can exceed 5000, usually originate from fallout from testing thermonuclear devices in the western Pacific in the 1950s. Natural mass ratios of chloride to bromide (Cl-/Br-) in precipitation vary in the United States from about 250 in coastal areas to about 50 in the north-central states. Lower ratios may suggest contamination from human sources. Higher ratios, which may exceed 2000, commonly reflect the dissolution of halite. Seawater has a Cl-/Br- ratio of 290. Both 36Cl and Cl-/Br- ratios have been measured in 21 samples of spring water collected from springs in 10 different states. Brackish water from Saratoga Springs area in New York has low values for both 36Cl and Cl-/Br- ratios. This indicates that a large component of the water has a very deep origin. Brackish water from Alexander Springs in Florida has a low 36Cl ratio but a high Cl-/Br- ratio similar to seawater. This suggests the addition of ancient seawater that may be trapped in the aquifer. Big Spring in Iowa discharges water with a very high Cl-/Br- ratio but a moderate 36Cl ratio. The high ratio of Cl-/Br- may be produced by dissolution of road salt or agricultural chemicals. Of the 21 springs sampled, only 10 appeared to have potable water not significantly affected by human activity. Chlorine-36 from testing of nuclear devices is still being flushed out of four of the spring systems that were sampled. Thus, more than 45 years have passed since 36Cl was introduced into the aquifers feeding the springs and the systems, as yet, have not been purged. Published by Elsevier Science B.V.
11. Aclidinium bromide combined with formoterol inhibits remodeling parameters in lung epithelial cells through cAMP.
Science.gov (United States)
Lambers, Christopher; Costa, Luigi; Ying, Qi; Zhong, Jun; Lardinois, Didier; Dekan, Gerhard; Schuller, Elisabeth; Roth, Michael
2015-12-01
Combined muscarinic receptor antagonists and long acting β2-agonists improve symptom control in chronic obstructive pulmonary disease (COPD) significantly. In clinical studies aclidinium bromide achieved better beneficial effects than other bronchodilators; however, the underlying molecular mechanisms are unknown. This study assessed the effect of aclidinium bromide combined with formoterol on COPD lung (n=20) and non-COPD lung (n=10) derived epithelial cells stimulated with TGF-β1+carbachol on: (i) the generation of mesenchymal cells in relation to epithelial cells, (II) extracellular matrix (ECM) deposition, and (iii) the interaction of ECM on the generation of epithelial and mesenchymal cells. TGF-β1+carbachol enhanced the generation of mesenchymal cells, which was significantly reduced by aclidinium bromide or formoterol. The effect of combined drugs was additive. Inhibition of p38 MAP kinase and Smad by specific inhibitors or aclidinium bromide reduced the generation of mesenchymal cells. In mesenchymal cells, TGF-β1+carbachol induced the deposition of collagen-I and fibronectin which was prevented by both drugs dose-dependently. Formoterol alone reduced collagen-I deposition via cAMP, this however, was overruled by TGF-β1+carbachol and rescued by aclidinium bromide. Inhibition of fibronectin was cAMP independent, but involved p38 MAP kinase and Smad. Seeding epithelial cells on ECM collagen-I and fibronectin induced mesenchymal cell generation, which was reduced by aclidinium bromide and formoterol. Our results suggest that the beneficial effect of aclidinium bromide and formoterol involves cAMP affecting both, the accumulation of mesenchymal cells and ECM remodeling, which may explain the beneficial effect of the drugs on lung function in COPD. PMID:26546746
12. Reversed phase-high performance liquid chromatographic method to measure migration of semivolatile compound, vanillin, in ipratropium bromide inhalation solution
OpenAIRE
Conkins, Dennis; Economou, Julia E; Boersma, James A; Dedhiya, Mehendra G; Hansen, Gordon
1999-01-01
Ipratropium bromide, a bronchodilator, is used as an inhalation solution. Commercial ipratropium bromide solution products are packaged in low-density polyethylene (LDPE) vials, through which semivolatile compounds are reported to migrate. In this article, a specific reversed phase-high performance liquid chromatographic method to assay vanillin, a semivolatile compound, in ipratropium bromide solution is described. The method was validated for a concentration range for vanillin from 30 ng/mL...
13. [Bowel obstruction-induced cholinergic crisis with progressive respiratory failure following distigmine bromide treatment].
Science.gov (United States)
Kobayashi, Kazuki; Sekiguchi, Hiroshi; Sato, Nobuhiro; Hirose, Yasuo
2016-03-01
A 54-year-old female experienced rapid respiratory failure while being transported in an ambulance to our emergency department for evaluation and management of constipation and abdominal pain. The patient was on treatment with distigmine bromide for postoperative urination disorder and magnesium oxide for constipation. Increased salivary secretions, diminished respiratory excursion, type 2 respiratory failure (PaCO2 : 65 mmHg), low serum cholinesterase, and hypermagnesemia were detected. Imaging studies revealed that the patient had bilateral aspiration pneumonia, fecal impaction in the rectum, and a distended colon causing ileus. The patient was mechanically ventilated and was weaned off the ventilator on day 3. Therapeutic drug monitoring after discharge revealed that the serum level of distigmine bromide on admission was markedly elevated (377.8 ng/mL vs. the normal therapeutic level of 5-10 ng/mL). Distigmine bromide induced a cholinergic crisis with a resultant increase in airway secretions and respiratory failure. In this particular case, orally administered distigmine bromide was excessively absorbed because of prolonged intestinal transit time secondary to fecal impaction and sluggish bowel movement; this caused a cholinergic crisis and hypermagnesemia contributing to respiratory failure. Clinicians should be aware that bowel obstruction in a patient treated with distigmine bromide can increase the risk of a cholinergic crisis. PMID:27255021
14. Use of radioanalytical methods for determination of uranium, neptunium, plutonium, americium and curium isotopes in radioactive wastes
International Nuclear Information System (INIS)
Activated charcoal is a common type of radioactive waste that contains high concentrations of fission and activation products. The management of this waste includes its characterization aiming the determination and quantification of the specific radionuclides including those known as Difficult-to-Measure Radionuclides (RDM). The analysis of the RDM's generally involves complex radiochemical analysis for purification and separation of the radionuclides, which are expensive and time-consuming. The objective of this work was to define a methodology for sequential analysis of the isotopes of uranium, neptunium, plutonium, americium and curium present in a type of radioactive waste, evaluating chemical yield, analysis of time spent, amount of secondary waste generated and cost. Three methodologies were compared and validated that employ ion exchange (TI + EC), extraction chromatography (EC) and extraction with polymers (ECP). The waste chosen was the activated charcoal from the purification system of primary circuit water cooling the reactor IEA-R1. The charcoal samples were dissolved by acid digestion followed by purification and separation of isotopes with ion exchange resins, extraction and chromatographic extraction polymers. Isotopes were analyzed on an alpha spectrometer, equipped with surface barrier detectors. The chemical yields were satisfactory for the methods TI + EC and EC. ECP method was comparable with those methods only for uranium. Statistical analysis as well the analysis of time spent, amount of secondary waste generated and cost revealed that EC method is the most effective for identifying and quantifying U, Np, Pu, Am and Cm present in charcoal. (author)
15. Intramolecular sensitization of americium luminescence in solution: shining light on short-lived forbidden 5f transitions.
Science.gov (United States)
Sturzbecher-Hoehne, M; Yang, P; D'Aléo, A; Abergel, R J
2016-06-14
The photophysical properties and solution thermodynamics of water soluble trivalent americium (Am(III)) complexes formed with multidentate chromophore-bearing ligands, 3,4,3-LI(1,2-HOPO), Enterobactin, and 5-LIO(Me-3,2-HOPO), were investigated. The three chelators were shown to act as antenna chromophores for Am(III), generating sensitized luminescence emission from the metal upon complexation, with very short lifetimes ranging from 33 to 42 ns and low luminescence quantum yields (10(-3) to 10(-2)%), characteristic of Near Infra-Red emitters in similar systems. The specific emission peak of Am(III) assigned to the (5)D1 → (7)F1 f-f transition was exploited to characterize the high proton-independent stability of the complex formed with the most efficient sensitizer 3,4,3-LI(1,2-HOPO), with a log β110 = 20.4 ± 0.2 value. In addition, the optical and solution thermodynamic features of these Am(III) complexes, combined with density functional theory calculations, were used to probe the influence of electronic structure on coordination properties across the f-element series and to gain insight into ligand field effects.
16. Nano-cerium vanadate: a novel inorganic ion exchanger for removal of americium and uranium from simulated aqueous nuclear waste.
Science.gov (United States)
Banerjee, Chayan; Dudwadkar, Nilesh; Tripathi, Subhash Chandra; Gandhi, Pritam Maniklal; Grover, Vinita; Kaushik, Chetan Prakash; Tyagi, Avesh Kumar
2014-09-15
Cerium vanadate nanopowders were synthesized by a facile low temperature co-precipitation method. The product was characterized by X-ray diffraction and transmission electron microscopy and found to consist of ∼25 nm spherical nanoparticles. The efficiency of these nanopowders for uptake of alpha-emitting radionuclides (233)U (4.82 MeV α) and (241)Am (5.49 MeV α, 60 keV γ) has been investigated. Thermodynamically and kinetically favorable uptake of these radionuclides resulted in their complete removal within 3h from aqueous acidic feed solutions. The uptake capacity was observed to increase with increase in pH as the zeta potential value decreased with the increase in pH but effect of ionic strength was insignificant. Little influence of the ions like Sr(2+), Ru(3+), Fe(3+), etc., in the uptake process indicated CeVO4 nanopowders to be amenable for practical applications. The isotherms indicated predominant uptake of the radioactive metal ions in the solid phase of the exchanger at lower feed concentrations and linear Kielland plots with positive slopes indicated favorable exchange of the metal ions with the nanopowder. Performance comparison with the other sorbents reported indicated excellent potential of nano-cerium vanadate for removing americium and uranium from large volumes of aqueous acidic solutions.
17. Distribution of plutonium, americium, and several rare earth fission product elements between liquid cadmium and LiCl-KCl eutectic
International Nuclear Information System (INIS)
Separation factors were measured that describe the partition between molten cadmium and molten LiCl-KCl eutectic of plutonium, americium, praseodymium, neodymium, cerium, lanthanum, gadolinium, dysprosium, and yttrium. The temperature range was 753-788 K, and the range of concentrations was that allowed by the sensitivity of the chemical analysis methods. Mean separation factors were derived for Am-Pu, Nd-Am, Nd-Pu, Nd-Pr, Gd-La, Dy-La, La-Ce, La-Nd, Y-La, and Y-Nd. Where previously published data were available, agreement was good. For convenience, the following series of separation factors relative to plutonium was derived by combining the measured separation factors: Pu, 1.00 (basis); Am, 1.54; Pr, 22.0; Nd, 23.4; Ce, 26; La, 70; Gd, 77; Dy, 270; Y, 3000. These data are used in calculating the distribution of the actinide and rare earth elements in the prochemical reprocessing of spent fuel from the Integral Fast Reactor. (orig.)
18. Evaluation of synthetic water-soluble metal-binding polymers with ultrafiltration for selective concentration of americium and plutonium
International Nuclear Information System (INIS)
Routine counting methods and ICP-MS are unable to directly measure the new US Department of Energy (DOE) regulatory level for discharge waters containing alpha-emitting radionuclides of 30 pCi/L total alpha or the 0.05 pCi/L regulatory level for Pu or Am activity required for surface waters at the Rocky Flats site by the State of Colorado. This inability indicates the need to develop rapid, reliable, and robust analytical techniques for measuring actinide metal ions, particularly americium and plutonium. Selective separation or preconcentration techniques would aid in this effort. Water-soluble metal-binding polymers in combination with ultrafiltration are shown to be an effective method for selectively removing dilute actinide ions from acidic solutions of high ionic strength. The actinide-binding properties of commercially available water-soluble polymers and several polymers which have been reported in the literature were evaluated. The functional groups incorporated in the polymers were pyrrolidone, amine, oxime, and carboxylic, phosphonic, or sulfonic acid. The polymer containing phosphonic acid groups gave the best results with high distribution coefficients and concentration factors for 241Am(III) and 238Pu(III)/(IV) at pH 4 to 6 and ionic strengths of 0.1 to 4
19. Characteristics of plutonium and americium contamination at the former U.K. atomic weapons test ranges at Maralinga and Emu
International Nuclear Information System (INIS)
Physico-chemical studies on environmental plutonium are described, which provide data integral to an assessment of dose for the inhalation of artificial actinides by Australian Aborigines living a semi-traditional lifestyle at Maralinga and Emu, sites of U.K. atomic weapons tests between 1953 and 1963. The most significant area, from a radiological perspective, is the area contaminated by plutonium in a series of ''one point'' safety trials in which large quantities of plutonium were dispersed explosively at a location known as Taranaki. The activity distribution of plutonium and americium with particle size is quite different from the mass distribution, as a considerably higher proportion of the activity is contained in the finer (inhalable) fraction than of the mass. Except in areas which were disturbed through ploughing during a cleanup in 1967, most the activity remains in the top 1 cm of the surface. Much of the activity is in particulate form, even at distances > 20 km from the firing sites, and discrete particles have been located even at distances beyond 100 km. Data are presented which permit the assessment of annual committed doses through the inhalation pathway, for Aborigines living a semi-traditional lifestyle in the areas affected by the Taranaki firings in particular. (author)
20. Current and Potential Future Bromide Loads from Coal-Fired Power Plants in the Allegheny River Basin and Their Effects on Downstream Concentrations.
Science.gov (United States)
Good, Kelly D; VanBriesen, Jeanne M
2016-09-01
The presence of bromide in rivers does not affect ecosystems or present a human health risk; however, elevated concentrations of bromide in drinking water sources can lead to difficulty meeting drinking water disinfection byproduct (DBP) regulations. Recent attention has focused on oil and gas wastewater and coal-fired power plant wet flue gas desulfurization (FGD) wastewater bromide discharges. Bromide can be added to coal to enhance mercury removal, and increased use of bromide at some power plants is expected. Evaluation of potential increases in bromide concentrations from bromide addition for mercury control is lacking. The present work utilizes bromide monitoring data in the Allegheny River and a mass-balance approach to elucidate bromide contributions from anthropogenic and natural sources under current and future scenarios. For the Allegheny River, the current bromide is associated approximately 49% with oil- and gas-produced water discharges and 33% with coal-fired power plants operating wet FGD, with 18% derived from natural sources during mean flow conditions in August. Median wet FGD bromide loads could increase 3-fold from 610 to 1900 kg/day if all plants implement bromide addition for mercury control. Median bromide concentrations in the lower Allegheny River in August would rise to 410, 200, and 180 μg/L under low-, mean-, and high-flow conditions, respectively, for the bromide-addition scenario. PMID:27538590
1. Corrosion Behavior of Austenitic and Duplex Stainless Steels in Lithium Bromide
Directory of Open Access Journals (Sweden)
Ayo Samuel AFOLABI
2009-07-01
Full Text Available The corrosion behavior of austenitic and duplex stainless steels in various concentrations of lithium, bromide solution was investigated by using the conventional weight loss measurement method. The results obtained show that corrosion of these steels occurred due to the aggressive bromide ion in the medium. Duplex stainless steel shows a greater resistance to corrosion than austenitic stainless steel in the medium. This was attributed to equal volume proportion of ferrite and austenite in the structure of duplex stainless steel coupled with higher content of chromium in its composition. Both steels produced electrochemical noise at increased concentrations of lithium bromide due to continuous film breakdown and repair caused by reduction in medium concentration by the alkaline corrosion product while surface passivity observed in duplex stainless steel is attributed to film stability on this steel.
2. Chloride/bromide ratios in leachate derived from farm-animal waste
International Nuclear Information System (INIS)
Results have important implications for identifying animal sources of contaminated groundwater. - Ratios of conservative chemicals have been used to identify sources of groundwater contamination. While chloride/bromide ratios have been reported for several common sources of groundwater contamination, little work has been done on leachate derived from farm-animal waste. In this study, chloride/bromide ratios were measured in leachate derived from longhorn-cattle, quarter-horse, and pygme-goat waste at a farm in Abilene, Texas, USA. (Minimum, median, and maximum) chloride/bromide ratios of (66.5, 85.6, and 167), (119, 146, and 156), and (35.4, 57.8, and 165) were observed for cattle, horses, and goats, respectively. These ratios are below typical values for domestic wastewater and within the range commonly observed for oilfield brine. Results of this study have important implications for identifying sources of contaminated groundwater in settings with significant livestock and/or oil production
3. Inhibitory effect of pinaverium bromide on gastrointestinal contractile activity in conscious dogs.
Science.gov (United States)
Itoh, Z; Takahashi, I
1981-01-01
The inhibitory effect of 4-(6-bromoveratryl)-4-(2-[2-(6,6-dimethyl-2-norpinyl)-ethoxy]-ethyl)-morpholinium hydroxide (pinaverium bromide), a quaternary ammonium derivative, on the contractile activity of the gastrointestinal tract from the stomach to the colon was investigated in six conscious dogs. Gastrointestinal motor activity was monitored by means of chronically implanted force transducers. Pinaverium bromide was continuously administered i.v. for 30 min in doses of 10 and 20 mg/kg/h during both the digestive and interdigestive states. It was found that pinaverium bromide strongly inhibited gastrointestinal contractile activity during both the digestive and interdigestive states; contractions in the stomach were most strongly inhibited; however, those in the small and large bowels were also significantly inhibited. No significant side effects in the circulatory and respiratory systems and the gastrointestinal tract such as nausea, vomiting or diarrhea were observed during and after the infusion of this agent. PMID:7197953
4. Irradiation as a disinfestation method - update on methyl bromide phase out, regulatory action and emerging opportunities
International Nuclear Information System (INIS)
5. Thermodynamic evaluation of new absorbent mixtures of lithium bromide and organic salts for absorption refrigeration machines
Energy Technology Data Exchange (ETDEWEB)
Donate, Marina; Rodriguez, Luis; Lucas, Antonio De; Rodriguez, Juan F. [Department of Chemical Engineering, University of Castilla-La Mancha, Avda. de Camilo Jose Cela s/n, 13004 Ciudad Real (Spain)
2006-01-01
Mixtures of lithium bromide and organic salts of sodium and potassium (formate, acetate and lactate) have been evaluated as alternative absorbents for absorption refrigeration machines. The main objective is to overpass the limitations of lithium bromide and improve the characteristics and the efficiency of the refrigeration cycle. In order to select the mixture that presents better properties for its employment in absorption refrigeration cycles, a thermodynamic analysis have been done. Density, viscosity, enthalpies of dilution, solubility and vapour pressure data of the proposed mixtures have been measured. A simulation program has been developed to evaluate temperatures, heats exchanged in the different sections and the efficiency of the cycle. (author)
6. COMPARISON OF ROCURONIUM BROMIDE AND SUCCINYLCHOLINE CHLORIDE FOR USE DURING RAPID SEQUENCE INTUBATION IN ADULTS
Directory of Open Access Journals (Sweden)
Ch. Penchalaiah
2015-08-01
Full Text Available BACKGROUND AND OBJECTIVE : The goal of rapid sequence intubation is to secure the patients airway smoothly and quickly, minimizing the chances of regurgitation and aspiration of gastric contents. Traditionally succinylcholine chloride has been the neuromuscular blocking drug of choi ce for use in rapid sequence intubation because of its rapid onset of action and profound relaxation. Succinylcholine chloride remains unsurpassed in providing ideal intubating conditions. However the use of succinylcholine chloride is associated with many side effects like muscle pain, bradycardia, hyperkalaemia and rise in intragastric and intraocular pressure. Rocuronium bromide is the only drug currently available which has the rapidity of onset of action like succinylcholine chloride. Hence the present study was undertaken to compare rocuronium bromide with succinylcholine chloride for use during rapid sequence intubation in adult patients. METHODOLOGY : The study population consisted of 90 patients aged between 18 - 60 years posted for various elective su rgeries requiring general anaesthesia . S tudy population was randomly divided into 3 groups with 30 patients in each sub group. 1. Group I : Intubated with 1 mg kg - 1 of succinylcholine chloride (n=30 . 2. Grou p II : Intubated with rocuronium bromide 0.6 mg kg - 1 (n=30 . 3. Group III : Intubated with rocuronium bromide 0.9 mg kg - 1 (n=30 . Intubating conditions were assessed at 60 seconds based on the scale adopted by Toni Magorian et al. 1993. The haemodynamic para meters in the present study were compared using p - value obtained from student t - test . RESULTS : It was noted that succinylcholine chloride 1 mg kg - 1 body weight produced excellent intubating conditions in all patients. Rocuronium bromide 0.6 mg kg - 1 body we ight produced excellent intubating conditions in 53.33% of patients but produced good to excellent intubating conditions in 96.67% of patients. Rocuronium bromide 0.9 mg kg - 1
7. Cesium Enhances Long-Term Stability of Lead Bromide Perovskite-Based Solar Cells
OpenAIRE
Kulbak, Michael; Gupta, Satyajit; Kedem, Nir; Levine, Igal; Bendikov, Tatyana; Hodes, Gary; Cahen, David
2015-01-01
Direct comparison between perovskite-structured hybrid organic-inorganic - methyl ammonium lead bromide (MAPbBr3) and all-inorganic cesium lead bromide (CsPbBr3), allows identifying possible fundamental differences in their structural, thermal and electronic characteristics. Both materials possess a similar direct optical band-gap, but CsPbBr3 demonstrates a higher thermal stability than MAPbBr3. In order to compare device properties we fabricated solar cells, with similarly synthesized MAPbB...
8. Well-Defined Copper(I) Fluoroalkoxide Complexes for Trifluoroethoxylation of Aryl and Heteroaryl Bromides
KAUST Repository
Huang, Ronglu
2015-03-17
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Copper(I) fluoroalkoxide complexes bearing dinitrogen ligands were synthesized and the structure and reactivity of the complexes toward trifluoroethoxylation, pentafluoropropoxylation, and tetrafluoropropoxylation of aryl and heteroaryl bromides were investigated. Efficiency drive: A series of copper(I) fluoroalkoxide complexes bearing N,N ligands have been prepared and structurally characterized. These well-defined complexes serve as efficient reagents for the fluoroalkoxylation of aryl and heteroaryl bromides to produce a wide range of trifluoroethyl, pentafluoropropyl, and tetrafluoropropyl (hetero)aryl ethers in good to excellent yields.
9. Once-daily glycopyrronium bromide (Seebri Breezhaler(®)) for the treatment of chronic obstructive pulmonary disease (COPD)
DEFF Research Database (Denmark)
Ulrik, Charlotte Suppli
2015-01-01
also on health status. Furthermore, glycopyrronium bromide also has beneficial effects on dynamic hyperinflation and, probably by that, exercise tolerance. Glycopyrronium bromide has been shown to reduce the rate of exacerbations in patients with moderate to severe COPD, although as a secondary outcome...
10. The role of natural organic matter in the migration behaviour of americium in the Boom Clay - Part 1: migration experiments
International Nuclear Information System (INIS)
Full text of publication follows: In demonstrating the suitability of Boom Clay as reference site for studying the disposal of radioactive waste, the role of the relatively high amount of Natural Organic Matter (NOM) present in the Boom Clay on the mobility of critical radionuclides needs to be investigated thoroughly. It is generally accepted that trivalent actinides and lanthanides form strong complexes with humic substances. Complexation of these trivalent radionuclides with NOM present in the Boom Clay may therefore have two opposite effects. If complexed by the aqueous phase NOM (the mobile NOM), the radionuclide transport will be governed by the mobility of these dissolved radionuclide- NOM species. If complexed by the solid phase NOM (the immobile NOM) the migration will be retarded. One of the aims of the EC projects TRANCOM-Clay and TRANCOM-II was to investigate the role of mobile NOM as radionuclide carrier in order to develop a conceptual model for inclusion in a performance assessment (PA) model. The migration behaviour of Americium (used as an analogue for the critical radionuclide Pu) was investigated by complexing 241Am with radiolabelled (14C-labelled) NOM before passing through undisturbed Boom Clay cores contained in columns. The use of two different radionuclides, allows the migration behaviour of both the NOM and the Am to be followed. The results of the migration experiments showed that the Am-NOM complexes dissociated when they came into contact with Boom Clay and that the bulk of Am became immobilised (either as Am complexed to immobile NOM or sorbed to the mineral phase). Only a small percentage of the complex persisted as 'stabilised' Am-OM complex which exhibited slow dissociation kinetics upon moving through the Boom Clay. When the applied radionuclide source also contains Am in the form of an inorganic solid phase (when Am is applied above the solubility limit), a continuous source of Am exists to form 'temporarily stabilised' Am
11. Experimental study of Americium-241 biokinetics in Homarus Gammarus lobster. Analysis of the accumulation and detoxication mechanisms at the sub-cellular level; Etude experimentale des biocinetiques de lamericium-241 chez le homard homarus gammarus. Analyse des mecanismes daccumulation et de detoxication au niveau subcellulaire
Energy Technology Data Exchange (ETDEWEB)
Paquet, F.
1991-12-01
The Americium 241 radioelement accumulation and elimination rate and mechanisms in the lobster organism have been experimentally studied; incorporation and detoxification capacities of each organ are evaluated. The existence of various biological compartments is shown; the major role of the digestive gland in accumulation of the radioelement, its distribution towards the various organs, and its resorption is comprehensively described, with an analysis at the subcellular and molecular levels. 401 p., 65 fig., 43 tab., 428 ref.
12. Nano-cerium vanadate: A novel inorganic ion exchanger for removal of americium and uranium from simulated aqueous nuclear waste
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Chayan; Dudwadkar, Nilesh [Fuel Reprocessing Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tripathi, Subhash Chandra, E-mail: sctri001@gmail.com [Fuel Reprocessing Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Gandhi, Pritam Maniklal [Fuel Reprocessing Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Grover, Vinita [Waste Management Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kaushik, Chetan Prakash [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tyagi, Avesh Kumar, E-mail: aktyagi@barc.gov.in [Waste Management Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)
2014-09-15
Highlights: • Template free, low temperature synthesis of CeVO{sub 4} nanopowders. • Thermodynamically and kinetically favourable uptake of Am(III) and U(VI) exhibited. • K{sub d} and ΔG° values for Am(III) and U(VI) uptake in pH 1–6 are reported. • Interdiffusion coefficients and zeta potential values in pH 1–6 are reported. • Possible application in low level aqueous nuclear waste remediation. - Abstract: Cerium vanadate nanopowders were synthesized by a facile low temperature co-precipitation method. The product was characterized by X-ray diffraction and transmission electron microscopy and found to consist of ∼25 nm spherical nanoparticles. The efficiency of these nanopowders for uptake of alpha-emitting radionuclides {sup 233}U (4.82 MeV α) and {sup 241}Am (5.49 MeV α, 60 keV γ) has been investigated. Thermodynamically and kinetically favorable uptake of these radionuclides resulted in their complete removal within 3 h from aqueous acidic feed solutions. The uptake capacity was observed to increase with increase in pH as the zeta potential value decreased with the increase in pH but effect of ionic strength was insignificant. Little influence of the ions like Sr{sup 2+}, Ru{sup 3+}, Fe{sup 3+}, etc., in the uptake process indicated CeVO{sub 4} nanopowders to be amenable for practical applications. The isotherms indicated predominant uptake of the radioactive metal ions in the solid phase of the exchanger at lower feed concentrations and linear Kielland plots with positive slopes indicated favorable exchange of the metal ions with the nanopowder. Performance comparison with the other sorbents reported indicated excellent potential of nano-cerium vanadate for removing americium and uranium from large volumes of aqueous acidic solutions.
13. Plutonium, americium and radiocaesium in the marine environment close to the Vandellos I nuclear power plant before decommissioning
International Nuclear Information System (INIS)
The Vandellos nuclear power plant (NPP), releasing low-level radioactive liquid waste to the Mediterranean Sea, is the first to be decommissioned in Spain, after an incident which occurred in 1989. The presence, distribution and uptake of various artificial radionuclides (radiocaesium, plutonium and americium) in the environment close to the plant were studied in seawater, bottom sediments and biota, including Posidonia oceanica, fish, crustaceans and molluscs. Seawater, sediments and Posidonia oceanica showed enhanced levels in the close vicinity of the NPP, although the effect was restricted to its near environment. Maximum concentrations in seawater were 11.6±0.5 Bq m-3 and 16.9±1.2 mBq m-3 for 137Cs and 239,240Pu, respectively. When sediment concentrations were normalized to excess 210Pb, they showed both the short-distance transport of artificial radionuclides from the Vandellos plant and the long-distance transport of 137Cs from the Asco NPP. Posidonia oceanica showed the presence of various gamma-emitters attributed to the impact of the Chernobyl accident, on which the effect of the NPP was superimposed. Seawater, sediment and Posidonia oceanica collected near the plant also showed an enhancement of the plutonium isotopic ratio above the fallout value. The uptake of these radionuclides by marine organisms was detectable but limited. Pelagic fish showed relatively higher 137Cs concentrations and only in the case of demersal fish was the plutonium isotopic ratio increased. The reported levels constitute a set of baseline values against which the impact of the decommissioning operations of the Vandellos I NPP can be studied
14. Molten salt extraction (MSE) of americium from plutonium metal in CaCl2-KCl-PuCl3 and CaCl2-PuCl3 salt systems
International Nuclear Information System (INIS)
Molten salt extraction (MSE) of americium-241 from reactor-grade plutonium has been developed using plutonium trichloride salt in stationary furnaces. Batch runs with oxidized and oxide-free metal have been conducted at temperature ranges between 750 and 945C, and plutonium trichloride concentrations from one to one hundred mole percent. Salt-to-metal ratios of 0.10, 0.15, and 0 30 were examined. The solvent salt was either eutectic 74 mole percent CaCl2 endash 26 mole percent KCl or pure CaCl2. Evidence of trivalent product americium, and effects of temperature, salt-to-metal ratio, and oxide contamination on the americium extraction efficiency are given. 24 refs, 20 figs, 13 tabs
15. Transfer across the human gut of environmental plutonium, americium, cobalt, caesium and technetium: studies with cockles (Cerastoderma edule) from the Irish Sea.
Science.gov (United States)
Hunt, G J
1998-06-01
Our previous studies have indicated lower values of the gut transfer factor ('f1 values') for plutonium and americium in winkles (Littorina littorea) than adopted by ICRP. The present study was undertaken primarily to investigate whether this observation extends to other species. Samples of cockles (Carastoderma edule) from Ravenglass, Cumbria were eaten by volunteers who provided 24 h samples of urine and faeces. Urine samples indicated f1 values for cockles which were higher than for winkles; for plutonium these ranged overall up to 7 x 10(-4) with an arithmetic mean in the range (2-3) x 10(-4), and for americium up to 2.6 x 10(-4) with an arithmetic mean of 1.2 x 10(-4). Limited data based on volunteers eating cockles from the Solway suggest that f1 values for americium may be greater at distance from Sellafield. The measured values compare with 5 x 10(-4) used by the ICRP for environmental forms of both elements, which would appear to provide adequate protection when calculating doses from Cumbrian cockles. Data for other nuclides were obtained by analysing faecal samples from the volunteers who ate the Ravenglass cockles. Cobalt-60 showed an f1 value in the region of 0.2, twice the value currently used by ICRP. For 137Cs, variabilities were indicated in the range 0.08 to 0.43, within the ICRP value of f1 = 1.0. Technetium-99 gave f1 values up to about 0.6, in reasonable conformity with the ICRP value of 0.5.
16. Transfer across the human gut of environmental plutonium, americium, cobalt, caesium and technetium: studies with cockles (Cerastoderma edule) from the Irish Sea
Energy Technology Data Exchange (ETDEWEB)
Hunt, G.J. [CEFAS Laboratory, Lowestoft, Suffolk NR33 0HT (United Kingdom)
1998-06-01
Our previous studies have indicated lower values of the gut transfer factor ('f{sub L} values') for plutonium and americium in winkles (Littorina littorea) than adopted by ICRP. The present study was undertaken primarily to investigate whether this observation extends to other species. Samples of cockles (Cerastoderma edule) from Ravenglass, Cumbria were eaten by volunteers who provided 24 samples of urine and faeces. Urine samples indicated f{sub L} values for cockles which were higher than for winkles; for plutonium these ranged overall up to 7x10{sup -4} with an arithmetic mean in the range (2-3)x10{sup -4}, and for americium up to 2.6x10{sup -4} with an arithmetic mean of 1.2x10{sup -4}. Limited data based on volunteers eating cockles from the Solway suggest that f{sub L} values for americium may be greater at distance from Sellafield. The measured values compare with 5x10{sup -4} used by the ICRP for environmental forms of both elements, which would appear to provide adequate protection when calculating doses from Cumbrian cockles. Data for other nuclides were obtained by analysing faecal samples from the volunteers who ate the Ravenglass cockles. Cobalt-60 showed an f{sub L} value in the region of 0.2, twice the value currently used by ICRP. For {sup 137}Cs, variabilities were indicated in the range 0.08 to 0.43, within the ICRP value of f{sub L}=1.0. Technetium-99 gave f{sub L} values up to about 0.6, in reasonable conformity with the ICRP value of 0.5. (author)
17. Reduced rates and alternatives to methyl bromide for snapdragon production in Florida
Science.gov (United States)
A field trial was conducted to evaluate soil solarization, Midas™ (iodomethane:chloropicrin 50:50, Arysta LifeScience Corp., Cary, NC) and different rates and formulations of methyl bromide under standard and metalized films for the production of snapdragon (Antirrhinum majus) in Martin County, Flor...
18. Iodine catalyzed and tertiary butyl ammonium bromide promoted p reparation of b enzoxazaphosphininyl phenylboronates
Directory of Open Access Journals (Sweden)
K. R. Kishore K. Reddy,
2009-05-01
Full Text Available Benzoxazaphosphininyl Phenylboronates were prepared by O-Phosphorylation of potassium salt ofphenylboronic acid with cyclic phosphoromonochloridates in the presence of stoichiometric amount of Iodineand catalytic amount of tertiary butyl ammonium bromide at 50-60 °C in dry toluene.
19. Effect of increasing bromide concentration on toxicity in treated drinking water.
Science.gov (United States)
Sawade, Emma; Fabris, Rolando; Humpage, Andrew; Drikas, Mary
2016-04-01
Research is increasingly indicating the potential chronic health effects of brominated disinfection by-products (DBPs). This is likely to increase with elevated bromide concentrations resulting from the impacts of climate change, projected to include extended periods of drought and the sudden onset of water quality changes. This will demand more rigorous monitoring throughout distribution systems and improved water quality management at water treatment plants (WTPs). In this work the impact of increased bromide concentration on formation of DBPs following conventional treatment and chlorination was assessed for two water sources. Bioanalytical tests were utilised to determine cytotoxicity of the water post disinfection. Coagulation was shown to significantly reduce the cytotoxicity of the water, indicating that removal of natural organic matter DBP precursors continues to be an important factor in drinking water treatment. Most toxic species appear to form within the first half hour following disinfectant addition. Increasing bromide concentration across the two waters was shown to increase the formation of trihalomethanes and shifted the haloacetic acid species distribution from chlorinated to those with greater bromine substitution. This correlated with increasing cytotoxicity. This work demonstrates the challenges faced by WTPs and the possible effects increasing levels of bromide in source waters could have on public health. PMID:27105403
20. Palladium-Catalyzed Carbonylation of Aryl Bromides with N-Substituted Cyanamides
DEFF Research Database (Denmark)
Lian, Zhong; Friis, Stig D.; Lindhardt, Anders T.;
2014-01-01
The palladium(0)-catalyzed three-component coupling reaction of aryl bromides, carbon monoxide, and N-alkyl cyanamides has been developed employing a two-chamber system with ex situ generation of carbon monoxide from a silacarboxylic acid. The reactions proceeded well and were complete with a...
1. Mild Pd-catalyzed aminocarbonylation of (hetero)aryl bromides with a palladacycle precatalyst.
Science.gov (United States)
Friis, Stig D; Skrydstrup, Troels; Buchwald, Stephen L
2014-08-15
A palladacyclic precatalyst is employed to cleanly generate a highly active XantPhos-ligated Pd-catalyst. Its use in low temperature aminocarbonylations of (hetero)aryl bromides provides access to a range of challenging products in good to excellent yields with low catalyst loading and only a slight excess of CO. Some products are unattainable by traditional carbonylative coupling.
2. Palladium-catalyzed carbonylative sonogashira coupling of aryl bromides using near stoichiometric carbon monoxide
DEFF Research Database (Denmark)
Neumann, Karoline T.; Laursen, Simon R.; Lindhardt, Anders T.;
2014-01-01
A general procedure for the palladium-catalyzed carbonylative Sonogashira coupling of aryl bromides is reported, using near stoichiometric amounts of carbon monoxide. The method allows a broad substrate scope in moderate to excellent yields. The formed alkynone motive serves as a platform for...
3. Measurement and Computation of Movement of Bromide Ions and Carbofuran in Ridged HUmic-Sandy Soil
NARCIS (Netherlands)
Leistra, M.; Boesten, J.J.T.I.
2010-01-01
Water flow and pesticide transport in the soil of fields with ridges and furrows may be more complex than in the soil of more level fields. Prior to crop emergence, the tracer bromide ion and the insecticide carbofuran were sprayed on the humic-sandy soil of a potato field with ridges and furrows. R
4. Methyl Bromide Alternatives Area-Wide Pest Management Project - South Atlantic Progress Report
Science.gov (United States)
Protocols and Standard Operational Procedures (SOPs) were developed for collecting environmental and soil edaphic information during and after application of methyl bromide alternatives. Parameters measured included soil moisture, soil bulk density, percent moisture at field capacity (-0.3 bars wat...
5. Bromate formation from bromide oxidation by the UV/persulfate process.
Science.gov (United States)
Fang, Jing-Yun; Shang, Chii
2012-08-21
Bromate formation from bromide oxidation by the UV/persulfate process was investigated, along with changes in pH, persulfate dosages, and bromide concentrations in ultrapure water and in bromide-spiked real water. In general, the bromate formation increased with increasing persulfate dosage and bromide concentration. The bromate formation was initiated and primarily driven by sulfate radicals (SO(4)(•-)) and involved the formation of hypobromous acid/hypobromite (HOBr/OBr(-)) as an intermediate and bromate as the final product. Under the test conditions, the rate of the first step driven by SO(4)(•-) is slower than that of the second step. Direct UV photolysis of HOBr/OBr(-) to form bromate and the photolysis of bromate are insignificant. The bromate formation was similar for pH 4-7 but decreased over 90% with increasing pH from 7 to above 9. Less bromate was formed in the real water sample than in ultrapure water, which was primarily attributable to the presence of natural organic matter that reacts with bromine atoms, HOBr/OBr(-) and SO(4)(•-). The extent of bromate formation and degradation of micropollutants are nevertheless coupled processes unless intermediate bromine species are consumed by NOM in real water. PMID:22831804
6. Strontium and bromide as tracers in X-ray microanalysis of biological tissue
Energy Technology Data Exchange (ETDEWEB)
Wroblewski, J.; Sagstroem, S.M.; Mulders, H.; Roomans, G.M. (Karolinska Institutet, Stockholm (Sweden))
1989-09-01
Since energy dispersive X-ray microanalysis cannot distinguish between isotopes of the same element, alternative methods have to be used to get information similar to that obtained in experiments with radioactive tracers. In the present study, strontium was used as a tracer for calcium, and bromide as a tracer for chloride. Rats were injected with strontium chloride in vivo, and the uptake of strontium in the acinar cells of the submandibular gland was studied. Eventually a Sr/Ca ratio of 0.3 was reached. In some animals, secretion of mucus had been elicited by stimulation with isoproterenol 4 h prior to injection of strontium chloride. Exchange of calcium for strontium was enhanced by prior injection with isoproterenol. In a second experiment, rats were injected with sodium bromide, and the uptake of bromide by the submandibular acinar cells was followed in time, both in pilocarpine-stimulated and unstimulated glands. Under the experimental conditions, bromide was rapidly taken up by the cells, and the cellular Br/Cl ratio was close to that found in serum. Submandibular glands take up Br somewhat faster than other tissues (liver, heart muscle, skeletal muscle). The uptake of Br in pancreatic acinar cells was studied in vitro. These experiments showed a 1:1 ratio (molar) exchange of Cl for Br.
7. Effects of intraoperative magnetic resonance imaging on the neuromuscular blockade of vecuronium bromide in neurosurgery
International Nuclear Information System (INIS)
The effects of intraoperative magnetic resonance (iMR) imaging on the neuromuscular blockade of vecuronium bromide were investigated in neurosurgery. Fifty patients with American Society of Anesthesiologists grades I-II scheduled for craniotomy operation were divided into two groups (n=25 each) with no difference in demographic data: the iMR imaging group and control group. Train-of-four (TOF) stimulation through an accelerometer was used to monitor onset, maintenance, and recovery of muscle relaxation caused by vecuronium. Vecuronium bromide was intravenously injected after anesthesia induction. The dosage of vecuronium bromide in the iMR imaging group was larger than in the control group, but not significantly. Duration of vecuronium bromide administration and operation time were significantly longer in the iMR imaging group than in the control group. Time from drug discontinuation to operation termination, and to return to neurosurgery intensive care unit were not different. Time taken by first twitch (T1) in response to TOF stimulation to recover by 25%, and muscle relaxant recovery index were significantly greater in the control group than in the iMR imaging group. The body temperature of the patients increased gradually in the iMR imaging group but decreased in the control group. iMR imaging can prolong the operation time, increase the body temperature of the patient, and remarkably shorten the clinical action time and muscle relaxation recovery index of vecuronium. (author)
8. Facile Syntheses of N-Substituted Imidazoles and Benzotriazoles from Baylis-Hillman Bromides
Institute of Scientific and Technical Information of China (English)
YE Dongyan; LI Jian; LI Chunju; JIA Xueshun
2009-01-01
A facile synthesis of N-substituted imidazole and benzotriazole derivatives from Baylis-Hiilman bromides with imidazole and benzotriazole at room temperature was reported. In view of the simple operation, mild reaction con-ditions, good to excellent yields, good regio- and stereoselectivity, the present method exhibited its superiority.
DEFF Research Database (Denmark)
Crestey, François; Ottesen, Lars Korsgaard; Jaroszewski, Jerzy Witold;
2008-01-01
The Letter describes an improved, rapid and mild strategy for the loading of primary alcohols onto a polystyrene trityl resin via a highly reactive trityl bromide linker. This protocol facilitates an efficient resin loading even of acid-sensitive or heat-labile alcohols, which otherwise require...
10. Methyl bromide release from activated carbon and the soil/water/carbon interface
Science.gov (United States)
Methyl Bromide (MB) is a major source of stratospheric bromine radical, a known depletor of ozone. The use of ozone-depleting chemicals, including MB, is regulated by the Montreal Protocol. Critical uses of MB are permitted, such as when postharvest fumigation is mandated by an importing country. Fo...
11. SYNTHESIS AND CATALYTIC PROPERTIES OF CROSS-LINKED HYDROPHOBICALLY ASSOCIATING POLY(ALKYLMETHYLDIALLYLAMMONIUM BROMIDES)
NARCIS (Netherlands)
WANG, GJ; ENGBERTS, JBFN
1994-01-01
Cross-linked, hydrophobically associating homo- and copolymers were synthesized by free-radical cyclo(co)polymerization of alkylmethyldiallylammonium bromide monomers with a small amount of N,N'-methylenebisacrylamide in aqueous solution using ammonium persulfate as the initiator. The cross-linked h
12. Effect of increasing bromide concentration on toxicity in treated drinking water.
Science.gov (United States)
Sawade, Emma; Fabris, Rolando; Humpage, Andrew; Drikas, Mary
2016-04-01
Research is increasingly indicating the potential chronic health effects of brominated disinfection by-products (DBPs). This is likely to increase with elevated bromide concentrations resulting from the impacts of climate change, projected to include extended periods of drought and the sudden onset of water quality changes. This will demand more rigorous monitoring throughout distribution systems and improved water quality management at water treatment plants (WTPs). In this work the impact of increased bromide concentration on formation of DBPs following conventional treatment and chlorination was assessed for two water sources. Bioanalytical tests were utilised to determine cytotoxicity of the water post disinfection. Coagulation was shown to significantly reduce the cytotoxicity of the water, indicating that removal of natural organic matter DBP precursors continues to be an important factor in drinking water treatment. Most toxic species appear to form within the first half hour following disinfectant addition. Increasing bromide concentration across the two waters was shown to increase the formation of trihalomethanes and shifted the haloacetic acid species distribution from chlorinated to those with greater bromine substitution. This correlated with increasing cytotoxicity. This work demonstrates the challenges faced by WTPs and the possible effects increasing levels of bromide in source waters could have on public health.
13. 76 FR 29238 - Methyl Bromide; Cancellation Order for Registration Amendments To Terminate Certain Soil Uses
Science.gov (United States)
2011-05-20
... provided, EPA received no comments in response to the February 9, 2011, Federal Register notice (76 FR 7200... AGENCY Methyl Bromide; Cancellation Order for Registration Amendments To Terminate Certain Soil Uses... for the amendments to terminate soil uses, voluntarily requested by the registrants and accepted...
14. Ozone decomposition under the irradiation of 253.7 nm in the presence of methyl bromide
Institute of Scientific and Technical Information of China (English)
2000-01-01
In this paper the mechanism and kinetic of ozone decomposition under the irradiation of 253.7 nm UV-light were studied.The quantum yield of the ozone depletion in the presence of methyl bromide is further determined and a reaction model is provided to explain the experimental fact.
15. COMPARISON OF ONSET TIME, DURATION OF ACTION AND INTUBATING CONDITION SACHIEVED WITH SUXAMETHONIUM AND ROCURONIUM BROMIDE
OpenAIRE
Ajit P; Alok P; Devendra Singh
2013-01-01
Adverse event profile ofSuxamethonium which is still the relaxant of choice to facilitate tracheal intubation inspired us to conduct a study in which we compared Onset time, Duration of Action and Intubating Conditions Achieved with Suxametho nium and Rocuronium Bromide with the Help of TOF Guard. AIMS : W e compared the onset of relaxation time, intubating condition, and duration of action, the ...
16. Effect of pinaverium bromide on stress-induced colonic smooth muscle contractility disorder in rats
OpenAIRE
Dai, Yun; Liu, Jian-Xiang; Li, Jun-Xia; Xu, Yun-Feng
2003-01-01
AIM: To investigate the effect of pinaverium bromide, a L-type calcium channel blocker with selectivity for the gastrointestinal tract on contractile activity of colonic circular smooth muscle in normal or cold-restraint stressed rats and its possible mechanism.
17. Quantitative gas chromatographic mass spectrometric determination of pinaverium-bromide in human serum.
Science.gov (United States)
de Weerdt, G A; Beke, R P; Verdievel, H G; Barbier, F; Jonckheere, J A; de Leenheer, A P
1983-03-01
A method has been developed for quantitative determination of pinaverium-bromide, a quaternary ammonium derivative with papaverine-like activity, in human serum. The method involves a chloroform extraction of serum spiked with N-(6,6-dimethyl bicyclo[3.1.1]2-heptenyl-ethoxyethyl) perhydro-1,4-oxazine as internal standard. After evaporation of the solvent, and reduction of the residue with Raney-Nickel, the internal standard and the reduced pinaverium-bromide are re-extracted from the reaction mixture with toluene and analysed isothermally on a fused silica column coated with OV-101. Although chemical ionization with methane revealed intense protonated molecular ions for both pinaverium-bromide and the internal standard, selectivity and sensitivity were significantly lower in comparison with electron impact ionization at 70 e V. Therefore, quantification was performed in the electron impact mode by single ion monitoring of the common fragment ion at m/z 100.2. A linear detector response was observed up to 160 ng ml-1. A within-run assay precision better than 2% CV (n = 5) was found, and a detection limit of 1 ng pinaverium-bromide ml-1 of serum was attained. PMID:6850068
18. TRIBROMOPYRROLE, BROMINATED ACIDS, AND OTHER DISINFECTION BYPRODUCTS PRODUCED BY DISINFECTION OF DRINKING WATER RICH IN BROMIDE
Science.gov (United States)
Using gas chromatography/mass spectrometry (GC/MS), we investigated the formation of disinfection byproducts (DBPs) from high bromide waters (2 mg/L) treated with chlorine or chlorine dioxide used in combination with chlorine and chloramines. This study represents the first comp...
19. Determination by gamma-ray spectrometry of the plutonium and americium content of the Pu/Am separation scraps. Application to molten salts; Determination par spectrometrie gamma de la teneur en plutonium et en americium de produits issus de separation Pu/Am. Application aux bains de sels
Energy Technology Data Exchange (ETDEWEB)
Godot, A. [CEA Valduc, Dept. de Traitement des Materiaux Nucleaires, 21 - Is-sur-Tille (France); Perot, B. [CEA Cadarache, Dept. de Technologie Nucleaire, Service de Modelisation des Transferts et Mesures Nucleaires, 13 - Saint-Paul-lez-Durance (France)
2005-07-01
Within the framework of plutonium recycling operations in CEA Valduc (France), americium is extracted from molten plutonium metal into a molten salt during an electrolysis process. The scraps (spent salt, cathode, and crucible) contain extracted americium and a part of plutonium. Nuclear material management requires a very accurate determination of the plutonium content. Gamma-ray spectroscopy is performed on Molten Salt Extraction (MSE) scraps located inside the glove box, in order to assess the plutonium and americium contents. The measurement accuracy is influenced by the device geometry, nuclear instrumentation, screens located between the sample and the detector, counting statistics and matrix attenuation, self-absorption within the spent salt being very important. The purpose of this study is to validate the 'infinite energy extrapolation' method employed to correct for self-attenuation, and to detect any potential bias. We present a numerical study performed with the MCNP computer code to identify the most influential parameters and some suggestions to improve the measurement accuracy. A final uncertainty of approximately 40% is achieved on the plutonium mass. (authors)
20. An experimental study of americium-241 biokinetics in the Lobster Homarus Gammarus. Analysis of the accumulation/storage and detoxification processes at the subcellular level; Etude experimentale des biocinetiques de lamericium-241 chez le homard homarus gammarus. Analyse des mecanismes daccumulation et de detoxication au niveau subcellulaire
Energy Technology Data Exchange (ETDEWEB)
Paquet, F.
1993-01-01
An experimental study of americium-241 kinetics has been conducted in the lobster Homarus gammmarus. The investigations were conducted at all the levels from the whole body to the subcellular and molecular levels. The animals were contaminated by a single or chronic ingestion of {sup 241} Am labelled mussels. Assessments of accumulation, elimination and distribution of the radionuclide were established on organisms kept in the laboratory; they made it possible to demonstrate the importance of the digestive gland in the radionuclide transfer pathways. The preliminary results led to structural then ultrastructural investigations of the digestive gland in association with radioautographic studies and cellular extractions methods. Four cellular types were demonstrated, only two of them being implied in the radionuclide retention, the former being responsible for americium intake and the latter for its long-term retention. By means of biochemical techniques, subcellular accumulation was studied and the organelles implied in the nuclide retention were specified. Finally, a method of cellular nuclei dissociation was developed; it made it possible to analyse the molecular nature of americium ligands and to demonstrate the function of the protein nuclear matrix in the nuclide retention.
1. Dissertation on the computer-based exploitation of a coincidence multi parametric recording. Application to the study of the disintegration scheme of Americium 241
International Nuclear Information System (INIS)
After having presented the meaning of disintegration scheme (alpha and gamma emissions, internal conversion, mean lifetime), the author highlights the benefits of the use of multi-parametric chain for the recording of correlated parameters, and of the use of a computer for the analysis of bi-parametric information based on contour lines. Using the example of Americium 241, the author shows how these information are obtained (alpha and gamma spectrometry, time measurement), how they are chosen, coded, analysed and stored, and then processed by contour lines
2. Reaction of Polymer-supported Selenovinyl Bromide with Grignard Reagents: A Facile Route to the Synthesis of(E)-1, 2-Disubstituted Olefins
Institute of Scientific and Technical Information of China (English)
E TANG; Xiang Jin LIN; Lu Ling WU
2005-01-01
Polymer-supported selenovinyl bromide, easily prepared from polymer-supported selenenyl bromide with acetylene, reacts with different Grignard reagents using a step-by-step strategy to obtain (E)-1, 2-disubstituted ethenes in good yields.
3. Kinetics of Chlorination of Benzophenone-3 in the Presence of Bromide and Ammonia.
Science.gov (United States)
Abdallah, Pamela; Deborde, Marie; Dossier Berne, Florence; Karpel Vel Leitner, Nathalie
2015-12-15
The aim of this study was to assess the impact of chlorination on the degradation of one of the most commonly used UV filters (benzophenone-3 (BP-3)) and the effects of bromide and ammonia on the kinetics of BP-3 elimination. Bromide and ammonia are rapidly converted to bromine and chloramines during chlorination. At first, the rate constants of chlorine, bromine and monochloramine with BP-3 were determined at various pH levels. BP-3 was found to react rapidly with chlorine and bromine, with values of apparent second order rate constants equal to 1.25(±0.14) × 10(3) M(-1)·s(-1) and 4.04(±0.54) × 10(6) M(-1)·s(-1) at pH 8.5 for kChlorine/BP-3 and kBromine/BP-3, respectively, whereas low monochloramine reactivity was observed (kNH2Cl/BP-3 = 0.112 M(-1)·s(-1)). To assess the impact of the inorganic content of water on BP-3 degradation, chlorination experiments with different added concentrations of bromide and/or ammonia were conducted. Under these conditions, BP-3 degradation was found to be enhanced in the presence of bromide due to the formation of bromine, whereas it was inhibited in the presence of ammonia. However, the results obtained were pH dependent. Finally, a kinetic model considering 18 reactions was developed using Copasi to estimate BP-3 degradation during chlorination in the presence of bromide and ammonia.
4. [Effectiveness of pinaverium bromide therapy on colonic motility disorders in irritable bowel syndrome].
Science.gov (United States)
Wittmann, T; Fehér, A; Rosztóczy, A; Jánosi, J
1999-02-28
The special patterns of the slow wave activity in irrittable bowel syndrome by means of surface electromyography were examined and the effect of pinaverium bromide on the symptoms and on the colonic motility in this disease was estimated. Twenty two patients with irritable bowel syndrome and 7 healthy controls were selected to the study. The clinical symptoms were abdominal pain and bloating in all patients, constipation in 9, and diarrhoea in 6 cases. Surface electromyography was carried out before and on the 14th day of the treatment with pinaverium bromide (50 mg t. i. d). The colonic motility was analysed in a 2 hour fasting and a 2 hour postprandial period following a standard (800 kCal) meal. The slow wave frequency of 0.01-0.04 Hz were selected and analysed. The mean frequency of activity peaks (n/10 min) and power-index (area under curve, microV 10 min) were measured. For statistical analysis Student's t-test was applied. Electromyogram of patients with irritable bowel syndrome showed a significant increase of the measured colonic motility parameters both in fasting and postprandial states. Fourteen days of pinaverium bromide treatment was able to significantly reduce the intensity of the colonic motor activity. Administration of pinaverium bromide completely released in 6 and significantly improved the abdominal pain in other 12 patients, while the bloating disappeared in 12 and was significantly improved in 5 from 22 patients. Pinaverium bromide was able to normalise the stool frequency: the weekly number of stools was decreased from 16 to 7 in the patients complaining diarrhoea ant it was increased from 2 to 6 in the patients with constipation. PMID:10204402
5. Determination of bromine contents in blood and hair of workers exposed to methyl by radioactivation analysis method bromide
International Nuclear Information System (INIS)
The bromine contained in blood and hair samples obtained from workers exposed to methyl bromide was analyzed by nondestructive activation analysis. The samples were irradiated for 1 min in pneumatic irradiation facility of Kyoto University research reactor with an estimated thermal neutron flux density at 2 x 1013 n.cm-2.sec-1. The irradiation was counted with Ge(Li) detector. The duration of measurement of radionuclide bromine in blood and hair was 200 sec within 2 - 10 min after irradiation. The bromine content of serum sample obtained from a worker suspected of methyl bromide poisoning was found to be 412 μg/g on 13 days apart from exposure to methyl bromide. The biological half-life of bromine in this case was found to be about 16 days. Then bromine contents in serum and hair samples obtained from workers exposed to methyl bromide were found to be 1.7 and 2.6 times higher respectively than those of nonexposed workers. Any correlations of bromine contents were not observed between serum and hair samples obtained from workers exposed to methyl bromide, nor between bromine amount in the serum of workers exposed to methyl bromide and the terms exposed to it, but statistically significant positive correlation was observed between bromine amount in the hair of workers exposed to methyl bromide and the terms exposed to it. (author)
6. Comparative microvascular exchange kinetics of [{sup 77}Br]bromide and {sup 99m}Tc-DTPA in humans
Energy Technology Data Exchange (ETDEWEB)
Cousins, Claire [Department of Clinical Radiology, Addenbrooke' s Hospital, Cambridge (United Kingdom); Skehan, Stephen J.; Rolph, Susan M.; Flaxman, Mary E.; Ballinger, James R.; Bird, Nicholas J.; Barber, Robert W.; Peters, Michael A. [Department of Nuclear Medicine, Addenbrooke' s Hospital, Cambridge (United Kingdom)
2002-05-01
The plasma clearance curves of small hydrophilic solutes comprise three exponentials, consistent with a three-compartmental distribution model. A previous comparison between inulin and diethylene triamine penta-acetic acid (DTPA) suggested that these three compartments are in series, the first being plasma and the second and third representing compartments within the extravascular space. Moreover, whilst the total distribution volumes of these two indicators were similar, the volume of the second compartment was higher for DTPA. The purpose of the current study was to investigate whether a solute smaller than DTPA, namely bromide, fits the hypothesis that the second space volume is an inverse function of the size of the solute. Two groups of subjects were studied: group A comprised eight patients undergoing routine diagnostic arteriography and group B, eight patients referred for routine measurement of glomerular filtration rate plus two normal volunteers. {sup 99m}Tc-DTPA and sodium [{sup 77}Br]bromide were intravenously administered simultaneously. In group A, frequent arterial samples were obtained up to 40 min after injection, and antecubital venous samples 30 s after each arterial sample. In group B, frequent venous samples were obtained up to 280 min after injection. Volume measurements based on bromide were corrected for erythrocyte bromide accumulation. In both subject groups, the normalised venous concentration ratio of bromide to DTPA, corrected for red cell bromide uptake, was significantly less than unity in the earliest blood samples, being 0.56 (SD 0.08) at 1 min, consistent with faster diffusion of bromide from plasma to interstitial fluid. Furthermore, the extraction fraction of bromide from plasma to interstitial fluid in the forearm was about 0.6, higher than that of DTPA (about 0.5) in spite of red cell bromide accumulation which equilibrated with plasma bromide within 20 s and resulted in a red cell to plasma concentration ratio of 0.51 (0
7. Synthesis of polyhydroxylated pyrrolidines from sugar-derived bromonitriles through a cascade addition of allylmagnesium bromide/cyclization/reduction.
Science.gov (United States)
Malik, Michał; Jarosz, Sławomir
2016-02-01
The synthesis of polyhydroxylated 2-allylpyrrolidines from sugar-derived bromonitriles in a cascade addition of allylmagnesium bromide/SN2 cyclization/reduction with Zn(BH4)2 is described. The stereochemical course of the reduction step is rationalized. Two of the obtained compounds are transformed into stereoisomers of naturally-occurring iminosugar (+)-lentiginosine. In an alternative approach, 2,2-diallylpyrrolidines are obtained from bromonitriles in a cascade addition of allylmagnesium bromide/SN2 cyclization/addition of another equivalent of allylmagnesium bromide.
8. A novel model-based approach for dose determination of glycopyrronium bromide in COPD
Directory of Open Access Journals (Sweden)
Arievich Helen
2012-12-01
Full Text Available Abstract Background Glycopyrronium bromide (NVA237 is an inhaled long-acting muscarinic antagonist in development for treatment of COPD. This study compared the efficacy and safety of once-daily (OD and twice-daily (BID glycopyrronium bromide regimens, using a novel model-based approach, in patients with moderate-to-severe COPD. Methods Double-blind, randomized, dose-finding trial with an eight-treatment, two-period, balanced incomplete block design. Patients (smoking history ≥10 pack-years, post-bronchodilator FEV1 ≥30% and 1/FVC 1 at Day 28. Results 385 patients (mean age 61.2 years; mean post-bronchodilator FEV1 53% predicted were randomized; 88.6% completed. All OD and BID dosing regimens produced dose-dependent bronchodilation; at Day 28, increases in mean trough FEV1 versus placebo were statistically significant for all regimens, ranging from 51 mL (glycopyrronium bromide 12.5 μg OD to 160 mL (glycopyrronium bromide 50 μg BID. Pharmacodynamic steady-state was reached by Day 7. There was a small separation (≤37 mL between BID and OD dose–response curves for mean trough FEV1 at steady-state in favour of BID dosing. Over 24 hours, separation between OD and BID regimens was even smaller (FEV1 AUC0-24h maximum difference for equivalent daily dose regimens: 8 mL. Dose–response results for FEV1 at 12 hours, FEV1 AUC0-12h and FEV1 AUC0-4h at steady-state showed OD regimens provided greater improvement over placebo than BID regimens for total daily doses of 25 μg, 50 μg and 100 μg, while the reverse was true for OD versus BID regimens from 12–24 hours. The 12.5 μg BID dose produced a marginally higher improvement in trough FEV1 versus placebo than 50 μg OD, however, the response at 12 hours over placebo was suboptimal (74 mL. Glycopyrronium bromide was safe and well tolerated at all doses. Conclusions Glycopyrronium bromide 50 μg OD provides significant bronchodilation over a 24 hour period
9. Facile Synthesis of Heterocycles via 2-Picolinium Bromide and Antimicrobial Activities of the Products
Directory of Open Access Journals (Sweden)
Elham S. Darwish
2008-05-01
Full Text Available The 2-picolinium N-ylide 4, generated in situ from the N-acylmethyl-2-picolinium bromide 3, underwent cycloaddition to N-phenylmaleimide or carbon disulfideto give the corresponding cycloadducts 6 and 8, respectively similar reactions ofcompound 3 with some electron-deficient alkenes in the presence of MnO2 yielded theproducts 11 and 12. In addition, reaction of 4 with arylidene cyanothioacetamide andmalononitrile derivatives afforded the thiophene and aniline derivatives 15 and 17,respectively. Heating of picolinium bromide 3 with triethylamine in benzene furnished 2-(2-thienylindolizine (18. The structures of the isolated products were confirmed byelemental analysis as well as by 1H- and 13C-NMR, IR, and MS data. Both thestereochemistry and the regioselectivity of the studied reactions are discussed. Thebiological activity of the newly synthesized compounds was examined and showedpromising results.
10. Indirect complexometric determination of mercury(II) using potassium bromide as selective masking agent
International Nuclear Information System (INIS)
A complexometric method for the determination of mercury in presence of other metal ions based on the selective masking ability of potassium bromide towards mercury is described. Mercury(II) present in a given sample solution is first complexed with a known excess of EDTA and the surplus EDTA is titrated against zinc sulfate solution at pH 5-6 using xylenol orange as the indicator. A known excess of 10 % solution of potassium bromide is then added and the EDTA released from Hg-EDTA complex is titrated against standard zinc sulfate solution. Reproducible and accurate results are obtained for 8 mg to 250 mg of mercury(II) with a relative error ±0.28 % and standard deviations /leg 0.5 mg. The interference of various ions is studied. This method was applied to the determination of mercury(II) in its alloys. (author)
11. Thermodynamic Properties of Hydrogen + Tetra-n-Butyl Ammonium Bromide Semi-Clathrate Hydrate
Directory of Open Access Journals (Sweden)
Shunsuke Hashimoto
2010-01-01
Full Text Available Thermodynamic stability and hydrogen occupancy on the hydrogen + tetra-n-butyl ammonium bromide semi-clathrate hydrate were investigated by means of Raman spectroscopic and phase equilibrium measurements under the three-phase equilibrium condition. The structure of mixed gas hydrates changes from tetragonal to another structure around 95 MPa and 292 K depending on surrounding hydrogen fugacity. The occupied amount of hydrogen in the semi-clathrate hydrate increases significantly associated with the structural transition. Tetra-n-butyl ammonium bromide semi-clathrate hydrates can absorb hydrogen molecules by a pressure-swing without destroying the hydrogen bonds of hydrate cages at 15 MPa or over.
12. Effect of pinaverium bromide on jejunal motility and colonic transit time in healthy humans.
Science.gov (United States)
Bouchoucha, M; Salles, J P; Fallet, M; Frileux, P; Cugnenc, P H; Barbier, J P
1992-01-01
Pinaverium bromide is a specific calcium channel blocker used in the treatment of irritable bowel syndrome (IBS) for its spasmolytic activity. The aim of the present study was to evaluate the effect of orally administered pinaverium bromide on jejunal motility and total and segmental colonic transit time in control subjects. Gastrointestinal studies were performed in 10 healthy volunteers (30 +/- 3 years), before and after a treatment phase of 14 days (150 mg/d). Jejunal motility was measured by prolonged manometry (14 h) and colonic transit time by a multiple ingestion, single marker technique. No significant modification of phase III of the migrating motor complexes was demonstrated. On the contrary, a significant (p < 0.01) but weak decrease of the frequency of contraction was found. Unlike previous studies, no decrease of total or segmental colonic transit time was demonstrated. PMID:1421047
13. Formation pathways of brominated products from benzophenone-4 chlorination in the presence of bromide ions
Institute of Scientific and Technical Information of China (English)
Ming Xiao; Dongbin Wei; Liping Li; Qi Liu; Huimin Zhao; Yuguo Du
2014-01-01
The brominated products,formed in chlorination treatment of benzophenone-4 in the presence of bromide ions,were identified,and the formation pathways were proposed.Under disinfection conditions,benzophenone-4 would undertake electrophilic substitution generating mono-or di-halogenated products,which would be oxidized to esters and further hydrolyzed to phenol derivatives.The generated catechol intermediate would be transformed into furan-like heterocyclic product.The product species were pH-dependent,while benzophenone-4 ehmination was chlorine dose-dependent.When the chlorination treatment was performed on ambient water spiked with benzophenone-4 and bromide ions,most of brominated byproducts could be detected,and the acute toxicity significantly increased as well.
14. Synthesis of Dimethyl Aryl Acylsulfonium Bromides from Aryl Methyl Ketones in a DMSO-HBr System
OpenAIRE
Zhiling Cao; Dahua Shi; Yingying Qu; Chuanzhou Tao; Weiwei Liu; Guowei Yao
2013-01-01
A new, simplified method for the synthesis of dimethyl aryl acylsulfonium salts has been developed. A series of dimethyl aryl acylsulfonium bromides were prepared by the reaction of aryl methyl ketones with hydrobromic acid and dimethylsulfoxide (DMSO). This sulfonium salt confirms that bromine production and the bromination reaction take place in the DMSO-HBr oxidation system. What’s more, it is also a key intermediate for the synthesis of arylglyoxals.
15. Linear free energy relationship in reactions between diphenyl amine and benzyl bromides
S Ranga Reddy; P Manikyamba
2006-05-01
Rate of reaction between benzyl bromide and diphenyl amine is retarded by electron-donating groups and enhanced by electron-withdrawing groups present on the benzene ring of the substrate. Hammett's reaction constant of the reaction decreases with increase in temperature according to the equation, \\rho = -11.92 + 3.54/ T. Minimal structural effects observed are attributed to the fact that the isokinetic temperature of the reaction is close to the reaction temperature.
16. Comparison of injection drotaverine and injection valethamate bromide on duration and course of labor
OpenAIRE
2016-01-01
Background: Numerous drugs have been used to shorten the active phase of labor. How rationale is it to use these drugs to shorten the active phase of labor? Do they really shorten the duration of labor? What adverse effects do they have on the baby and the mother? These questions were the basis to perform the present study of comparing two of such drugs, injection drotaverine and injection Valethamate bromide with control subjects. Methods: This was a prospective study conducted in a terti...
17. Mechanism of HERG potassium channel inhibition by tetra-n-octylammonium bromide and benzethonium chloride
Energy Technology Data Exchange (ETDEWEB)
Long, Yan; Lin, Zuoxian [Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530 (China); Xia, Menghang; Zheng, Wei [National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892 (United States); Li, Zhiyuan, E-mail: li_zhiyuan@gibh.ac.cn [Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530 (China)
2013-03-01
Tetra-n-octylammonium bromide and benzethonium chloride are synthetic quaternary ammonium salts that are widely used in hospitals and industries for the disinfection and surface treatment and as the preservative agent. Recently, the activities of HERG channel inhibition by these compounds have been found to have potential risks to induce the long QT syndrome and cardiac arrhythmia, although the mechanism of action is still elusive. This study was conducted to investigate the mechanism of HERG channel inhibition by these compounds by using whole-cell patch clamp experiments in a CHO cell line stably expressing HERG channels. Tetra-n-octylammonium bromide and benzethonium chloride exhibited concentration-dependent inhibitions of HERG channel currents with IC{sub 50} values of 4 nM and 17 nM, respectively, which were also voltage-dependent and use-dependent. Both compounds shifted the channel activation I–V curves in a hyperpolarized direction for 10–15 mV and accelerated channel activation and inactivation processes by 2-fold. In addition, tetra-n-octylammonium bromide shifted the inactivation I–V curve in a hyperpolarized direction for 24.4 mV and slowed the rate of channel deactivation by 2-fold, whereas benzethonium chloride did not. The results indicate that tetra-n-octylammonium bromide and benzethonium chloride are open-channel blockers that inhibit HERG channels in the voltage-dependent, use-dependent and state-dependent manners. - Highlights: ► Tetra-n-octylammonium and benzethonium are potent HERG channel inhibitors. ► Channel activation and inactivation processes are accelerated by the two compounds. ► Both compounds are the open-channel blockers to HERG channels. ► HERG channel inhibition by both compounds is use-, voltage- and state dependent. ► The in vivo risk of QT prolongation needs to be studied for the two compounds.
18. Effect of Impeller Agitation on Preparation of Tetra-n-Butyl Ammonium Bromide Semiclathrate Hydrate Slurries
OpenAIRE
Yoshiro Inoue; Kazunari Ohgaki; Shunsuke Hashimoto; Hiroyuki Ito
2012-01-01
The slurries-containing tetra-n-butyl ammonium bromide (TBAB) solution and its semiclathrate hydrate have attracted a lot of interest as latent heat transport media. These hydrate slurries contain some microparticles of crystal, and the size and shape of these hydrate particles could affect the mobility of slurries. Hence, it is essential to investigate the efficient hydrate-slurry preparation methods and the effect of hydrate particles on the fluid property of slurries for the application to...
19. Acute hepatitis after starting pinaverium bromide in a patient taking mirtazapine
OpenAIRE
Tak, Sandeep; Tak, Shubhanjali
2014-01-01
A 56-year-old man presented with chronic abdominal pain. He had been evaluated extensively in the recent past undergoing upper gastrointestinal endoscopy, colonoscopy and CT scan of the abdomen with normal results. The provisional diagnosis of irritable bowel syndrome was performed and pinaverium bromide was started. The patient had pre-existing hypertension, a major depressive disorder and gastro-oesophageal reflux disease. He had been taking nebivolol and pantoprazole for several years and ...
20. Role of pinaverium bromide in south Indian patients with irritable bowel syndrome.
Science.gov (United States)
Jayanthi, V; Malathi, S; Ramathilakam, B; Dinakaran, N; Balasubramanian, V; Mathew, S
1998-04-01
The effect of pinaverium bromide in controlling gastrointestinal symptoms in 61 patients with irritable bowel syndrome was studied, as an open trial. Individually, there was significant relief in abdominal discomfort/pain as well as in bowel symptoms in most of the patients. Abdominal pain was reduced in 49%, stool consistency improved in 74%, straining and urgency decreased in 71% and mucus decreased in 64%. Tolerance to the drug administered was good and side-effects reported were few. PMID:11273320
1. Tetrabutylammonium Bromide (TBABr)-Based Deep Eutectic Solvents (DESs) and Their Physical Properties
OpenAIRE
Rizana Yusof; Emilia Abdulmalek; Kamaliah Sirat; Mohd. Basyaruddin Abdul Rahman
2014-01-01
Density, viscosity and ionic conductivity data sets of deep eutectic solvents (DESs) formed by tetrabutylammonium bromide (TBABr) paired with ethlyene glycol, 1,3-propanediol, 1,5-pentanediol and glycerol hydrogen bond donors (HBDs) are reported. The properties of DES were measured at temperatures between 303 K and 333 K for HBD percentages of 66.7% to 90%. The effects of HBDs under different temperature and percentages are systematically analyzed. As expected, the measured density and viscos...
2. Tiotropium bromide in the routine care of GOLD stage II COPD patients: a pharmaeconomic evaluation
OpenAIRE
Orietta Zaniolo; Michela Carsi; Sergio Iannazzo
2011-01-01
Background: a secondary pre-specified analysis of the UPLIFT cohort demonstrated that the inclusion of tiotropium bromide in the routine care of GOLD stage II (moderate) chronic obstructive pulmonary disease (COPD) patients is associated with stronger improvements of survival, quality of life, and exacerbation rate than those shown in the total cohort; in this subgroup, tiotropium furthermore induces a significant reduction in the rate of FEV1 decline.Objective: to adapt the Spiriva® model, o...
3. Flight Experiment to Study Double-Diffusive Instabilities in Silver-Doped Lead Bromide Crystals
Science.gov (United States)
Singh, N. B.; Rosch, W. R.; Suhre, D. R.; Coriell, S. R.; Duval, W. M. B.
1999-01-01
A detailed study on the effect of convection on crystal quality was carried out by growing lead bromide crystals in transparent Bridgman furnace. Direct observations were made on the solid-liquid interface and a new kind of instability was observed. This could be explained on the basis of toroidal flow in the AgBr-doped lead bromide sample. With the increasing translation velocity, the interface changed from flat to depressed, and then formed a cavity in the center of the growth tube. The crystal grown at the lowest thermal Rayleigh number showed the highest quality and crystal grown at the largest thermal Rayleigh number showed the worst quality. Numerical studies were carried out to provide a framework for interpreting the observed convective and morphological instabilities, and to determine the critical (limiting) concentration of dopant for a particular growth velocity and gravity level. Theoretical instability diagrams were compared with data obtained from the experimental studies. These studies provided basic data on convective behavior in doped lead bromide crystals grown by the commercially important Bridgman process.
4. A bio-product as alternative to methyl bromide for replant disease control on strawberry
Institute of Scientific and Technical Information of China (English)
Yu ZHANG; Tongle HU; Lijing JI; Keqiang CAO
2008-01-01
Pre-plant soil fumigation with methyl bromide (MB) is a standard practice for controlling soil-borne diseases especially for strawberry diseases. However, the application of MB will be forbidden in China in the year 2015. For this reason, a bio-product named Kangdi 3 was tested as an alternative to MB in strawberry greenhouses in Mancheng (Hebei Province) and Donggang (Liaoning province), China in 2005 and 2006. Methyl bromide at a normal dosage of 500 kg/hm2 and Kangdi 3 at three dosages of 750, 1500 and 2250 kg/hm2 were tested. Plots without any treatment were used as the control. During the growing stage, assessments were made on fungal communities in rhizosphere, growth status of strawberry, the disease levels on roots as well as the yields. Results showed that Kangdi 3 significantly reduced the quantity of fungi and the disease index, while enhancing strawberry growth and the yields compared with the untreated control. Therefore, Kangdi 3 is a great potential substitute for methyl bromide to control replant diseases in strawberry.
5. Transport of bromide measured by soil coring, suction plates, and lysimeters under transient flow conditions.
Science.gov (United States)
Kasteel, R.; Pütz, Th.; Vereecken, H.
2003-04-01
Lysimeter studies are one step within the registration procedure of pesticides. Flow and transport in these free-draining lysimeters do not reflect the field situation mainly because of the occurence of a zone of local saturation at the lower boundary (seepage face). The objective of this study is to evaluate the impact of flow and transport behaviour of bromide detected with different measuring devices (lysimeters, suction plates, and soil coring) by comparing experimental results with numerical simulations in heterogeneous flow domains. We applied bromide as a small pulse to the bare soil surface (Orthic Luvisol) of the three devices and the displacement of bromide was regurlarly sampled for three years under natural wheather conditions. Based on the mean breakthrough curves we observe experimentally that lysimeters have a lower effective pore-water velocity and exhibit more solute spreading resulting in a larger dispersivity than the suction plates. This can be ascribed to the artefact of the lower boundary. We performed numerical transport simulations in 2-D heterogeneous flow fields (scaling approach) choosing appropriate boundary conditions for the various devices. The simulations allow to follow the temporal evolution of flow and transport processes in the various devices and to gain additional process understanding. We conclude that the model is essentially capable to reproduce the main experimental findings only if we account for the spatial correlation structure of the hydraulic properties, i.e. soil heterogeneity.
6. Recent trends in atmospheric methyl bromide: analysis of post-Montreal Protocol variability
Directory of Open Access Journals (Sweden)
S. A. Yvon-Lewis
2009-03-01
Full Text Available The atmospheric methyl bromide (CH3Br burden has declined in recent years, in response to the phaseout of agricultural and structural fumigation consumption under the amendments to the Montreal Protocol. The timing and magnitude of this decrease represents an opportunity to examine our current understanding of the CH3Br budget, the phaseout schedule, and recent estimates of interannual variability in biomass burning and global OH. In this study, simulations obtained from a time-dependent global model of atmospheric CH3Br emissions and uptake are compared to observations from the NOAA flask network. The model includes an updated global methyl bromide source inventory that includes biofuel combustion emissions estimated at 6.1±3 Gg yr−1 globally. The phaseout of CH3Br production for agricultural uses began in 1998, concurrent with the pulse in biomass burning associated with the 1998 El Niño. The combined effects of three factors (biomass burning, global OH, and anthropogenic phaseout appear to explain most of the observed atmospheric methyl bromide trend over the 1997–2005 period. The global budget remains imbalanced, with a large missing source. These results suggest that more than 80% of the missing source does not exhibit significant interannual variability during the phaseout period and, therefore, does not result from underestimating agricultural CH3Br emissions.
7. Replacing methyl bromide in annual strawberry production with glucosinolate-containing green manure crops.
Science.gov (United States)
Lazzeri, Luca; Baruzzi, Gianluca; Malaguti, Lorena; Antoniacci, Loredana
2003-09-01
The use of biocidal green manure crops is an agronomic technique for amending soil with fresh organic matter containing volatile compounds active in controlling some soil-borne pests and diseases. Two new selections of the Brassicaceae family were cultivated, incorporated before planting strawberries and tested as an alternative to fumigation with methyl bromide. Two biocidal green manure crops (Brassica juncea L sel ISCI20, Eruca sativa Mill cv Nemat) containing glucosinolate-myrosinase systems, a conventional green manure (barley), untreated soil and a fumigated control were evaluated during two seasons. The effect of these soil management systems on subsequent strawberry performance was evaluated by monitoring yield and plant growth parameters. In both years, biocidal plant green manure treatments led to a fruit yield lower than with methyl bromide, but higher than with conventional green manure or untreated soil. These results confirm the good prospects for biocidal green manures, not only as an environmentally friendly alternative to methyl bromide in conventional agriculture, but also in organic agriculture as an alternative to conventional green manure crops.
8. Effects of oral pinaverium bromide on colonic response to food in irritable bowel syndrome patients.
Science.gov (United States)
Bouchoucha, M; Faye, A; Devroede, G; Arsac, M
2000-08-01
We have recently developed a simple method to investigate the colonic response to food (CRF). This study describes the modifications of CRF induced by treatment with oral pinaverium bromide in irritable bowel syndrome (IBS) patients. Thirty healthy subjects and 43 patients suffering from IBS were studied. Colonic transit time (CTT) was measured in fasting conditions and after eating a standard test meal. Colonic response to food was quantified by calculating the variation in number of markers in each zone of interest of the large bowel between the X-ray films of the abdomen taken before and after eating. CRF is characterized by caudal propulsion of colonic contents in the two groups. In controls, there is emptying of the caecum-ascending colon region and filling of the rectosigmoid. In IBS patients, only the left transverse colon and the splenic flexure empty. Pinaverium bromide exerts no effect in controls but reverses the CRF of the right colon in IBS patients by inhibiting right colon emptying. These results suggest that the inhibitory action of pinaverium bromide on CRF may support the clinical efficacy of this calcium channel blocker in the treatment of IBS. PMID:10989977
9. Inhibition of the colonic motor response to eating by pinaverium bromide in irritable bowel syndrome patients.
Science.gov (United States)
Fioramonti, J; Frexinos, J; Staumont, G; Bueno, L
1988-01-01
The effect of pinaverium bromide on the colonic motor response to eating was investigated in 10 irritable bowel syndrome patients, by means of an intraluminal probe supporting 8 groups of electrodes. At each site examined from transverse to sigmoid colon, the electromyograms exhibited 2 kinds of spike bursts: short spike bursts (SSB) localized at one electrode, and long spike bursts (LSB), isolated, propagated orally or aborally over a few centimeters, or aborally propagated over the whole length of the colon investigated (migrating long spike bursts, MLSB). Recordings were continuously performed over 24 hr. Each patient received at 7.00 p.m. on day 1 and at noon on day 2 an 800-1000 Kcal meal preceded by IV administration of pinaverium bromide (4 mg) or placebo. After placebo administration, the duration of LSB activity and the number of MLSB were significantly increased over 3 postprandial hr by comparison with the 2 hr preceding the meal. After pinaverium injection no significant postprandial change in LSB and MLSB activity was noted. The SSB activity was not modified after the meals preceded by placebo or pinaverium injection. These results suggest that the inhibitory action of pinaverium bromide on postprandial colonic motility may support the clinical efficacy of this agent in the treatment of the irritable bowel syndrome. PMID:3371838
10. Toxic impact of bromide and iodide on drinking water disinfected with chlorine or chloramines.
Science.gov (United States)
Yang, Yang; Komaki, Yukako; Kimura, Susana Y; Hu, Hong-Ying; Wagner, Elizabeth D; Mariñas, Benito J; Plewa, Michael J
2014-10-21
Disinfectants inactivate pathogens in source water; however, they also react with organic matter and bromide/iodide to form disinfection byproducts (DBPs). Although only a few DBP classes have been systematically analyzed for toxicity, iodinated and brominated DBPs tend to be the most toxic. The objectives of this research were (1) to determine if monochloramine (NH2Cl) disinfection generated drinking water with less toxicity than water disinfected with free chlorine (HOCl) and (2) to determine the impact of added bromide and iodide in conjunction with HOCl or NH2Cl disinfection on mammalian cell cytotoxicity and genomic DNA damage induction. Water disinfected with chlorine was less cytotoxic but more genotoxic than water disinfected with chloramine. For both disinfectants, the addition of Br(-) and I(-) increased cytotoxicity and genotoxicity with a greater response observed with NH2Cl disinfection. Both cytotoxicity and genotoxicity were highly correlated with TOBr and TOI. However, toxicity was weakly and inversely correlated with TOCl. Thus, the forcing agents for cytotoxicity and genotoxicity were the generation of brominated and iodinated DBPs rather than the formation of chlorinated DBPs. Disinfection practices need careful consideration especially when using source waters containing elevated bromide and iodide.
11. The Effect of Ozonation Process on Bromide-Containing Groundwaters in Bandung Area and Its Surroundings
Directory of Open Access Journals (Sweden)
Mindriany Syafila
2012-11-01
Full Text Available Disinfection process was applied as the last step of the water treatment to kill pathogenic bacteria in the water. However, according to several studies, the ozonation disinfection process could form undesired by-products. One of the by-products potentially affecting human life is bromate produced from bromide ionic-containing water. This study was carried out to examine the effect of raw water characteristics and pH on bromate formation. Also, the performance of bromate formation for a period of exposure time was analyzed. Raw waters taken from four different areas around Bandung were exposed to ozone introduced to a reactor with a flow rate of 2 L/min. The pH of the raw waters varied from 4, 7 to 10. The results show that there was no evidence of an initial bromide ion concentration, whereas a change in pH value gives a significantly different outcome. In acidic condition (pH of 4 the bromate formation tends to decrease, whereas when the pH value increases to a pH of 10, the bromate formation increases. Therefore, for drinking water with a neutral pH, when bromide ions are detected in the raw water, the drinking water may be toxic due to the presence of bromate.
12. Detection of water contamination from hydraulic fracturing wastewater: a μPAD for bromide analysis in natural waters.
Science.gov (United States)
Loh, Leslie J; Bandara, Gayan C; Weber, Genevieve L; Remcho, Vincent T
2015-08-21
Due to the rapid expansion in hydraulic fracturing (fracking), there is a need for robust, portable and specific water analysis techniques. Early detection of contamination is crucial for the prevention of lasting environmental damage. Bromide can potentially function as an early indicator of water contamination by fracking waste, because there is a high concentration of bromide ions in fracking wastewaters. To facilitate this, a microfluidic paper-based analytical device (μPAD) has been developed and optimized for the quantitative colorimetric detection of bromide in water using a smartphone. A paper microfluidic platform offers the advantages of inexpensive fabrication, elimination of unstable wet reagents, portability and high adaptability for widespread distribution. These features make this assay an attractive option for a new field test for on-site determination of bromide. PMID:26161586
13. Efficient ring-closing metathesis of alkenyl bromides: the importance of protecting the catalyst during the olefin approach.
Science.gov (United States)
Gatti, Michele; Drinkel, Emma; Wu, Linglin; Pusterla, Ivano; Gaggia, Fiona; Dorta, Reto
2010-11-01
We present the first productive ring-closing metathesis reaction that leads to the construction of cyclic alkenyl bromides. Efficient catalysis employing commercially available Grubbs II catalyst is possible through appropriate modification of the starting bromoalkene moiety.
14. Prostate cancer and toxicity from critical use exemptions of methyl bromide: Environmental protection helps protect against human health risks
Directory of Open Access Journals (Sweden)
Budnik Lygia T
2012-01-01
Full Text Available Abstract Background Although ozone-depleting methyl bromide was destined for phase-out by 2005, it is still widely applied as a consequence of various critical-use-exemptions and mandatory international regulations aiming to restrict the spread of pests and alien species (e.g. in globalized transport and storage. The withdrawal of methyl bromide because of its environmental risk could fortuitously help in the containment of its human toxicity. Methods We performed a systematic review of the literature, including in vitro toxicological and epidemiological studies of occupational and community exposure to the halogenated hydrocarbon pesticide methyl bromide. We focused on toxic (especially chronic or carcinogenic effects from the use of methyl bromide, on biomonitoring data and reference values. Eligible epidemiological studies were subjected to meta-analysis. Results Out of the 542 peer reviewed publications between 1990-2011, we found only 91 referring to toxicity of methyl bromide and 29 using the term "carcinogenic", "neoplastic" or "mutagenic". Several studies provide new additional data pertaining to the mechanistic aspects of methyl bromide toxicity. Few studies have performed a detailed exposure assessment including biomonitoring. Three evaluated epidemiological studies assessed a possible association between cancer and methyl bromide. Overall, exposure to methyl bromide is associated with an increased risk of prostate cancer OR, 1.21; 95% CI (0,98-1.49, P = 0.076. Two epidemiological studies have analyzed environmental, non-occupational exposure to methyl bromide providing evidence for its health risk to the general public. None of the epidemiological studies addressed its use as a fumigant in freight containers, although recent field and case reports do refer to its toxic effects associated with its use in shipping and storage. Conclusions Both the epidemiological evidence and toxicological data suggest a possible link between methyl
15. Inhaled americium dioxide
International Nuclear Information System (INIS)
This project includes experiments to determine the effects of Zn-DTPA therapy on the retention, translocation and biological effects of inhaled 241AmO2. Beagle dogs that received inhalation exposure to 241AmO2 developed leukopenia, clincial chemistry changes associated with hepatocellular damage, and were euthanized due to respiratory insufficiency caused by radiation pneumonitis 120 to 131 days after pulmonary deposition of 22 to 65 μCi 241Am. Another group of dogs that received inhalation exposure to 241AmO2 and were treated daily with Zn-DTPA had initial pulmonary deposition of 19 to 26 μCi 241Am. These dogs did not develop respiratory insufficiency, and hematologic and clinical chemistry changes were less severe than in the non-DTPA-treated dogs
16. Comparison of pinaverium bromide, manganese chloride and D600 effects on electrical and mechanical activities in rat uterine smooth muscle.
Science.gov (United States)
Mironneau, J; Lalanne, C; Mironneau, C; Savineau, J P; Lavie, J L
1984-02-10
The effects of pinaverium bromide, were compared with those of D600 and manganese chloride (Mn), on membrane potentials, ionic currents and isometric contractions in uterine smooth muscle strips from pregnant rats. Pinaverium bromide (10(-7) - 10(-6) M) depressed twitch contractions and K-contractures within 15-20 min while D600 (2 X 10(-6) M) and Mn (10(-3) M) abolished both contractions. D600 and pinaverium bromide were more potent inhibitors in K-depolarized preparations than in polarized tissues. At a supramaximal dose (10(-5) M), pinaverium bromide decreased the rate of rise, amplitude, and rate of repolarization of the action potential, and prolonged the potential duration. The inward Ca current was depressed and the reduction in Cai was responsible for the decrease in K current. Pinaverium bromide (10(-5) M) depressed the myometrial contractions induced in Ca-free solution by acetylcholine (10(-4) M) and by prolonged membrane depolarizations. Mn (2.5 X 10(-3) M) only reduced the Ach-induced contraction and D600 (10(-5) M) had no effect on intracellular Ca stores. The results indicate that pinaverium bromide has Ca channel blocking properties similar to those of currently used Ca antagonists; it may also exert an effect to depress contractions supported by intracellular Ca release. PMID:6325214
17. Recovery of Americium-241 from lightning rod by the method of chemical treatment; Recuperacion del Americio-241 provenientes de los pararrayos por el metodo de tratamiento quimico
Energy Technology Data Exchange (ETDEWEB)
Cruz, W.H., E-mail: wcruz@ipen.gob.pe [Instituto Peruano de Energia Nuclear (GRRA/IPEN), Lima (Peru). Division de Gestion de Residuos Radiactivos
2013-07-01
About 95% of the lightning rods installed in the Peruvian territory have set in their structures, pose small amounts of radioactive sources such as Americium-241 ({sup 241}Am), fewer and Radium 226 ({sup 226}Ra) these are alpha emitters and have a half life of 432 years and 1600 years respectively. In this paper describes the recovery of radioactive sources of {sup 241}Am radioactive lightning rods using the conventional chemical treatment method using agents and acids to break down the slides. The {sup 241}Am recovered was as excitation source and alpha particle generator for analysing samples by X Ray Fluorescence, for fixing the stainless steel {sup 241}Am technique was used electrodeposition. (author)
18. Partitioning studies in China and the separation of americium and fission product rare earths with dialkyl phosphinic acid and its thio-substituted derivatives
International Nuclear Information System (INIS)
Studies on the TRPO extractions process for recovering actinides from highly active waste (HAW) and its application to the pretreatment of Chinese HAW are described. The removal of Sr by di-cyclohexyl 18 crown 6 and the removal of Cs by spherical titanium ferrous hexa-cyanate from acidic waste are also described. Results of the extraction of trivalent americium and fission product rare earths (FPREs) by dialkyl-phosphinic, dialkyl-mono-thio-phosphinic and dialkyl-di-thio-phosphinic acids are reported. Dialkyl-thio-phosphinic acid (commercial product Cyanex 301, alkyl =2, 4, 4-methyl-pentyl) shows very high selectivity towards Am. Using 1M Cyanex 301 -kerosene as extractant, 99.9 % Am can be separated from 0.5M(Pr+Nd)(NO3)3 solution with 3-4 extraction stages and 3-4 scrubbing stages. (authors)
19. Theoretical and experimental study of the bio-geochemical behaviour of americium 241 in simplified rhizosphere conditions. Application to a calcareous agricultural soil
International Nuclear Information System (INIS)
Americium 241, is one of the most radio-toxic contaminant produced during the nuclear fuel cycle. It can be found in all environmental compartments, in particular the soils. The main goals of this study are to identify, quantify and model the effect of the main factors controlling the mobility of 241Am in the rhizosphere and the agricultural soils. The physico-chemical parameters of the soil and of the soil solution, the potential role of microorganisms on the sorption-desorption processes, and the speciation of americium in solution have been more particularly studied. 241Am remobilization has been studied at the laboratory using leaching experiments performed in controlled conditions on reworked calcareous soils artificially contaminated with 241Am. The soil samples have been washed out in different hydrodynamic conditions by solutions with various compositions. The eluted solution has been analyzed (pH, conductivity, ionic composition, Fetot, organic acids, 241Am) and its bacterial biomass content too. The overall results indicate that 241Am remobilization is contrasted and strongly linked with the condition under study (pH, ionic strength, glucose and/or citrate concentration). Therefore, a solution in equilibrium with the soil or containing small exudate concentrations (10-4 M) re-mobilizes only a very small part of the americium fixed on the solid phase. The desorption of 241Am corresponds to a solid/liquid coefficient of partition (Kd) of about 105 L.kg-1. A significant addition of glucose induces an important dissolution of soil carbonates by the indirect action of microorganisms, but does not significantly favor the 241Am remobilization. On the other hand, the presence of strong citrate concentrations (≥ 10-2 M) allows 300 to 10000 time greater re-mobilizations by the complexing of 241Am released after the dissolution of the carrying phases. Finally, the colloidal transport of 241Am has been systematically observed in a limited but significant extend and
20. Safe handling of kilogram amounts of fuel-grade plutonium and of gram amounts of plutonium-238, americium-241 and curium-244
International Nuclear Information System (INIS)
1. Measurement and computation of movement of bromide ions and carbofuran in ridged humic-sandy soil.
Science.gov (United States)
Leistra, Minze; Boesten, Jos J T I
2010-07-01
Water flow and pesticide transport in the soil of fields with ridges and furrows may be more complex than in the soil of more level fields. Prior to crop emergence, the tracer bromide ion and the insecticide carbofuran were sprayed on the humic-sandy soil of a potato field with ridges and furrows. Rainfall was supplemented by sprinkler irrigation. The distribution of the substances in the soil profile of the ridges and furrows was measured on three dates in the potato growing season. Separate ridge and furrow systems were simulated by using the pesticide emission assessment at regional and local scales (PEARL) model for pesticide behavior in soil-plant systems. The substances travelled deeper in the furrow soil than in the ridge soil, because of runoff from the ridges to the furrows. At 19 days after application, the peak of the bromide distribution was measured to be in the 0.1-0.2 m layer of the ridges, while it was in the 0.3-0.5 m layer of the furrows. After 65 days, the peak of the carbofuran distribution in the ridge soil was still in the 0.1 m top layer, while the pesticide was rather evenly distributed in the top 0.6 m of the furrow soil. The wide ranges in concentration measured with depth showed that preferential water flow and substance transport occurred in the sandy soil. Part of the bromide ion distribution was measured to move faster in soil than the computed wave. The runoff of water and pesticide from the ridges to the furrows, and the thinner root zone in the furrows, are expected to increase the risk of leaching to groundwater in ridged fields, in comparison with more level fields.
2. ACCIDENTAL SUBCUTANEOUS INJECTION OF VECURONIUM BROMIDE IN A PATIENT WITH BURNS
Directory of Open Access Journals (Sweden)
Usha Dev
2014-10-01
Full Text Available BACKGROUND AND OBJECTIVES: In patients with burn injury drug pharmacology will be altered and this poses special anaesthetic challenge when an subcutaneous injection of a non- depolarizing muscle relaxant occurs in such a patient. Small studies remain an important source of knowledge and hence this study aims to provide information on the anaesthetic management in a case of accidental subcutaneous injection of vecuronium bromide in a burns patient. PRESENTATION, DIAGNOSIS & MANAGEMENT: A 22 year young male with 4 days old hot water induced grade 1 burns involving 45% of body surface area was posted for burns dressing. Anaesthesia was induced with propofol and vecuronium bromide through an external jugular vein to aid tracheal intubation. As the patient was not anaesthetized even after 10 minutes routine check lead to the discovery of fullness at the tip of the intravenous catheter indicating an extravasation of the drugs. Hence the other external jugular vein was cannulated and the patient induced and intubated using propofol, sevoflurane, nitrous oxide and oxygen. The action of vecuronium outlasted the duration of surgery. So the patient continued to receive support of mechanical ventilation with nitrous oxide and oxygen. It took 130 minutes for the clinical signs of recovery from the muscle relaxant to manifest. He was then reversed & extubated with subsequent good recovery. CONCLUSION: Subcutaneous injection of these drugs poses problems of delayed onset of action and prolonged duration of action. In an inadvertent accidental subcutaneous 0.1 mg/kg vecuronium bromide injection in a patient with 4 day old 45% burns showed delayed onset action and prolonged neuromuscular blockade due to subcutaneous deposition of the drug which was managed with mechanical ventilation .The reported resistance to the action of NDMR drugs in patient with burns was not noticed here probably because of the age of the thermal injury.
3. Efficient SN2 fluorination of primary and secondary alkyl bromides by copper(I) fluoride complexes
KAUST Repository
Liu, Yanpin
2013-11-11
Copper(I) fluoride complexes ligated by phenanthroline derivatives have been synthesized and structurally characterized by X-ray crystallography. These complexes adopt as either ionic or neutral forms in the solid state, depending on the steric bulkiness of the substituent groups on the phenanthroline ligands. These complexes react with primary and secondary alkyl bromides to produce the corresponding alkyl fluorides in modest to good yields. This new method is compatible with a variety of important functional groups such as ether, thioether, amide, nitrile, methoxyl, hydroxyl, ketone, ester, and heterocycle moieties. © 2013 American Chemical Society.
4. Radiation Induced Formation of Acrylated Palm Oil Nanoparticles using Cetyltrimethylammonium Bromide Microemulsion System
International Nuclear Information System (INIS)
In this study, we report the preparation of Acrylated Palm Oil (APO) nanoparticles using aqueous Cetyltrimethylammonium bromide (CTAB) microemulsion system. This microemulsion system which contains the dispersed APO nano droplets was subjected to the gamma irradiation to induce the formation of the crosslinked APO nanoparticle. After irradiation at higher doses, the size of APO nanoparticles was transformed from a submicron-sized to a nano-sized of the particles. Size decreasing might be due to the intermolecular and the intramolecular crosslinking reactions of the APO nanoparticles during the irradiation process. (author)
5. Promotion of hexadecyltrimethyleamine bromide to the damage of Alexandrium sp. LC3 by cupric glutamate
Institute of Scientific and Technical Information of China (English)
LI Hao; MIAO Jin-lai; CUI Feng-xia; LI Guang-you
2006-01-01
The effect of hexadecyltrimethyleamine bromide (HDTMAB) on the removal of A lexandrium sp. LC3 under cupric glutamate stress was investigated. Toxic effect of cupric glutamate on A lexandrium sp. LC3 was significantly promoted in the presence of HDTMAB, especially at 3.0 cmc of HDTMAB. It was found that the sulfhydryl group content of the cell decreased, while the malonaldehyde content and membrane permeability increased when Alexandrium sp. LC3 was treated with HDTMAB and cupric glutamate complex, compared with cupric glutamate alone. The data suggest that HDTMAB might stimulate the damage of A lexandrium sp. LC3 by enhancing the membrane permeability.
6. Efficient Stille cross-coupling reaction using aryl chlorides or bromides in water.
Science.gov (United States)
Wolf, Christian; Lerebours, Rachel
2003-09-19
An efficient Stille cross-coupling reaction using a variety of aryl halides in neat water has been developed. Employing palladium-phosphinous acid catalyst [(t-Bu)(2)P(OH)](2)PdCl(2) allows formation of biaryls from aryl chlorides and bromides in good to high yields. Functional groups such as ketones and nitriles are tolerated, and organic cosolvents are not required. The air stability and solubility in water of the palladium complexes used in this study facilitate operation of the coupling reaction and product isolation. The feasibility of catalyst recycling has also been demonstrated. PMID:12968920
7. Highly stable, luminescent core-shell type methylammonium-octylammonium lead bromide layered perovskite nanoparticles.
Science.gov (United States)
Bhaumik, Saikat; Veldhuis, Sjoerd A; Ng, Yan Fong; Li, Mingjie; Muduli, Subas Kumar; Sum, Tze Chien; Damodaran, Bahulayan; Mhaisalkar, Subodh; Mathews, Nripan
2016-06-01
A new protocol for the synthesis of a highly stable (over 2 months under ambient conditions) solution-processed core-shell type structure of mixed methylammonium-octylammonium lead bromide perovskite nanoparticles (5-12 nm), having spherical shape, color tunability in the blue to green spectral region (438-521 nm) and a high photoluminescence quantum yield (PLQY) of up to 92% is described. The color tunability, high PLQY and stability are due to the quantum confinement imparted by the crystal engineering associated with core-shell nanoparticle formation during growth. PMID:27165565
8. Rapid Consumption of Low Concentrations of Methyl Bromide by Soil Bacteria
OpenAIRE
Hines, Mark E.; Crill, Patrick M; Varner, Ruth K.; Talbot, Robert W; Shorter, Joanne H.; Kolb, Charles E.; Harriss, Robert C.
1998-01-01
A dynamic dilution system for producing low mixing ratios of methyl bromide (MeBr) and a sensitive analytical technique were used to study the uptake of MeBr by various soils. MeBr was removed within minutes from vials incubated with soils and ∼10 parts per billion by volume of MeBr. Killed controls did not consume MeBr, and a mixture of the broad-spectrum antibiotics chloramphenicol and tetracycline inhibited MeBr uptake by 98%, indicating that all of the uptake of MeBr was biological and by...
9. Nitrate ion photolysis in thin water films in the presence of bromide ions.
Science.gov (United States)
Richards, Nicole K; Wingen, Lisa M; Callahan, Karen M; Nishino, Noriko; Kleinman, Michael T; Tobias, Douglas J; Finlayson-Pitts, Barbara J
2011-06-16
Nitrate ions commonly coexist with halide ions in aged sea salt particles, as well as in the Arctic snowpack, where NO(3)(-) photochemistry is believed to be an important source of NO(y) (NO + NO(2) + HONO + ...). The effects of bromide ions on nitrate ion photochemistry were investigated at 298 ± 2 K in air using 311 nm photolysis lamps. Reactions were carried out using NaBr/NaNO(3) and KBr/KNO(3) deposited on the walls of a Teflon chamber. Gas phase halogen products and NO(2) were measured as a function of photolysis time using long path FTIR, NO(y) chemiluminescence and atmospheric pressure ionization mass spectrometry (API-MS). Irradiated NaBr/NaNO(3) mixtures show an enhancement in the rates of production of NO(2) and Br(2) as the bromide mole fraction (χ(NaBr)) increased. However, this was not the case for KBr/KNO(3) mixtures where the rates of production of NO(2) and Br(2) remained constant over all values of χ(KBr). Molecular dynamics (MD) simulations show that the presence of bromide in the NaBr solutions pulls sodium toward the solution surface, which in turn attracts nitrate to the interfacial region, allowing for more efficient escape of NO(2) than in the absence of halides. However, in the case of KBr/KNO(3), bromide ions do not appreciably affect the distribution of nitrate ions at the interface. Clustering of Br(-) with NO(3)(-) and H(2)O predicted by MD simulations for sodium salts may facilitate a direct intermolecular reaction, which could also contribute to higher rates of NO(2) production. Enhanced photochemistry in the presence of halide ions may be important for oxides of nitrogen production in field studies such as in polar snowpacks where the use of quantum yields from laboratory studies in the absence of halide ions would lead to a significant underestimate of the photolysis rates of nitrate ions.
10. Cytotoxicity evaluation of Clinacanthus nutans through dimethylthiazol diphenyltetrazolium bromide and neutral red uptake assays
OpenAIRE
Vajrabhaya, La-Ongthong; Korsuwannawong, Suwanna
2016-01-01
Objectives: The aim of this study was to compare the results of dimethylthiazol diphenyltetrazolium bromide (MTT) and neutral red uptake (NRU) assays of Clinacanthus nutans cytotoxicity. Materials and Methods: Mouse fibroblast (L929) cells were exposed to 0.01%, 0.1%, 0.25%, and 0.5% (W/V) C. nutans in a 96-cluster-well-culture plate for 24 h. The cell viability after exposure to C. nutans was determined by MTT and NRU assays in separate tissue culture plates. The two assays were compared thr...
11. Ethidium bromide transport across Mycobacterium smegmatis cell-wall: correlation with antibiotic resistance
OpenAIRE
Couto Isabel; Ramos Jorge; Rodrigues Liliana; Amaral Leonard; Viveiros Miguel
2011-01-01
Abstract Background Active efflux systems and reduced cell-wall permeability are considered to be the main causes of mycobacterial intrinsic resistance to many antimicrobials. In this study, we have compared the Mycobacterium smegmatis wild-type strain mc2155 with knockout mutants for porins MspA (the main porin of M. smegmatis) and MspC, the efflux pump LfrA (the main efflux pump system of M. smegmatis) and its repressor LfrR for their ability to transport ethidium bromide (EtBr) on a real-t...
12. Generation, spectroscopy, and structure of cyanoformyl chloride and cyanoformyl bromide, XC(O)CN.
Science.gov (United States)
Pasinszki, Tibor; Vass, Gábor; Klapstein, Dieter; Westwood, Nicholas P C
2012-04-01
Cyanoformyl chloride and cyanoformyl bromide, XC(O)CN (X = Cl and Br), have been investigated in the gas phase by UV photoelectron and mid-infrared spectroscopies. The ground-state geometries of the neutral molecules have been obtained from quantum-chemical calculations at the B3LYP and CCSD(T) levels using the aug-cc-pVTZ basis set. The individual spectroscopies provide a detailed investigation into the vibrational and electronic character of the molecules and are supported by quantum-chemical calculations. The results are compared to data for structurally and chemically related molecules.
13. Bromine and bromide in rainfall, cloud, stream and groundwater in the Plynlimon area of mid-Wales
Directory of Open Access Journals (Sweden)
2007-01-01
Full Text Available Bromine in rainfall, cloud water, stream water and groundwater were measured in the upper River Severn catchments at Plynlimon in mid-Wales using two analytical procedures for bromide determination: a colorimetric method and, later, ion chromatography. Discrepancies between the methods indicated that the colorimetric method was measuring more than just bromide so it was "dissolved labile bromine" (DLBr (Neal et al., 2007. This paper reports the variation in DLBr and bromide across the Plynlimon region and assesses the differences between these two measures. The average DLBr concentration in the streams ranges between 18.3 and 27.8 µg l−1 compared with a rainfall average concentration of 15.6 µg l−1. The corresponding bromide concentrations in the streams are 13.8–18.6 µg l−1 and 13.2 µg l−1 in rainfall. For cloud water, throughfall and stemflow, DLBr concentrations are an order of magnitude higher than in rainfall and the concentrations are strongly correlated with chloride. Average values of bromide in rainfall and cloud water are similar to those of DLBr and are strongly correlated with chloride: unfortunately, no bromide measurements were taken in throughfall and stemflow. These results indicate that marine aerosol inputs are high and that the DLBr in these inputs is dominated by bromide. For cloud water, DLBr was correlated with dissolved organic carbon (DOC as well as with chloride; hence, there may well be an organic-associated component. Within the streams draining the forested areas, DLBr increases with time as DOC increases. DLBr concentrations in the streams are correlated with DOC in most cases and, to a lesser degree, with chloride. However, for bromide there is no correlation with DOC, but a weak correlation with chloride remains and the gradient is higher than for the DLBr case. Increasing concentrations of both DLBr and DOC may well reflect the wetting up of the catchments as transpiration diminshes as the trees age
14. Using prechloramination to control trihalomethanes formation in River Huang water with high bromide
Institute of Scientific and Technical Information of China (English)
TAO Hui; CHEN Wei; LIN Tao; LIU Cheng; CHEN Jie; LI Gui-bai
2008-01-01
An effective technology in controlling trihalomethanes (THMs)formation in the case of large amounts of bromide presenting wag proposed,and the water of River Huang seriously polluted by bromide in winter in Tianjin City wag studied.The THMs formation characteristics during prechloramination using preformed chloramines and convened chloramines were studied through jar tests.Results show that,in prechloramination process,the formation of THMs by preformed chloramines is very few,while that by converted chloramines is a little higher.And the formation of THMs,especially Br-substituted THMs,increases with tIle increase of time and Cl2:N ratio as well as the decrease of pH.The result obtained in a pilot plant shows that compared with preehlorination,the prechlommination process can efficiendy control the formation of THMs,especially the Br-substituted species.With equal chlorine dosage.the prechloramination can maintain a hrser chlorine residue which offers a larger CT value than prechlorination.
15. Moving away from methyl bromide: political economy of pesticide transition for California strawberries since 2004.
Science.gov (United States)
Mayfield, Erin N; Norman, Catherine Shelley
2012-09-15
We examine the progress of the phaseout of the use of the pesticide methyl bromide in the production of California field strawberries. This phaseout is required under the Montreal Protocol and has been contentious in this sector, which receives exemptions from the schedule initially agreed under the treaty, and in international negotiations over the future of the Protocol. We examine the various ex-ante predictions of the impacts on growers, consumers and trade patterns in light of several years of declining allocations under the Critical Use provisions of the Protocol and the 2010 approval of iodomethane for use in California and subsequent 2012 withdrawal of this alternative from the US market. We find that, contrary to ex-ante industry claims, the years of declining methyl bromide use have been years of rising yields, acreage, exports, revenues and market share for California growers, even when faced with a global recession and increased imports from Mexican growers who retain the right to use the chemical under the Protocol. This has implications for the Protocol as a whole and for the remainder of the US phaseout of this chemical in particular. PMID:22575205
16. Model prediction uncertainty of bromide and pesticides transport in laboratory column
Science.gov (United States)
Dusek, Jaromir; Dohnal, Michal; Snehota, Michal; Sobotkova, Martina; Ray, Chittaranjan; Vogel, Tomas
2016-04-01
Knowledge of transport parameters of reactive solutes such as pesticides is a prerequisite for reliable predictions of their fate and transport in soil porous systems. Water flow and transport of bromide tracer and five pesticides (atrazine, imazaquin, sulfometuron methyl, S-metolachlor, and imidacloprid) through an undisturbed soil column of tropical Oxisol were analyzed using a one-dimensional numerical model. Laboratory column leaching experiment with three flow interruptions was conducted. The applied numerical model is based on Richards' equation for solving water flow and the advection-dispersion equation for solving solute transport. A global optimization method was used to evaluate the model's sensitivity to transport parameters and the uncertainty of model predictions. Within the Monte Carlo modeling framework, multiple forward simulations searching through the parametric space, were executed to describe the observed breakthrough curves. All pesticides were found to be relatively mobile. Experimental data indicated significant non-conservative behavior of bromide tracer. All pesticides, with the exception of imidacloprid, were found less persistent. Three of the five pesticides (atrazine, sulfometuron methyl, and S-metolachlor) were better described by the linear kinetic sorption model, while the breakthrough curves of imazaquin and imidacloprid were more appropriately approximated using nonlinear instantaneous sorption. Sensitivity analysis suggested that the model is most sensitive to sorption distribution coefficient. The prediction limits contained most of the measured points of the experimental breakthrough curves, indicating adequate model concept and model structure for the description of transport processes in the soil column under study.
17. Recent trends in atmospheric methyl bromide: analysis of post-Montreal Protocol variability
Directory of Open Access Journals (Sweden)
S. A. Yvon-Lewis
2009-08-01
Full Text Available The atmospheric methyl bromide (CH3Br burden has declined in recent years, in response to the phaseout of agricultural and structural fumigation consumption under the amendments to the Montreal Protocol. The timing and magnitude of this decrease represents an opportunity to examine our current understanding of atmospheric CH3Br and its budget, response to the phaseout, and response to interannual variability in biomass burning and global OH. In this study, simulations obtained from a time-dependent global model of atmospheric CH3Br emissions and uptake are compared to observations from the NOAA flask network. The model includes a detailed gridded ocean model coupled to a time-dependant atmospheric 2-box model. The phaseout of CH3Br production for agricultural uses began in 1998, concurrent with the pulse in biomass burning associated with the 1998 El Niño. The combined effects of three factors (biomass burning, global OH, and anthropogenic phaseout appear to explain most of the observed atmospheric methyl bromide variability over the 1997–2008 period. The global budget remains imbalanced, with a large missing source indicated. The missing source does not exhibit a systematic decline during the phaseout period, and therefore, is not the result of significantly underestimating non-QPS agricultural CH3Br emissions. The model results suggest that the oceans should be less undersaturated than before the phaseout began.
18. Thermodynamics of micellization of hexadecyltrimethylammonium bromide in propylene glycol-water mixture: A conductivity study
Directory of Open Access Journals (Sweden)
Janošević-Ležaić Aleksandra M.
2014-01-01
Full Text Available Micellization of hexadecyltrimethylammonium bromide (syn. cetyltrimethylammonium bromide, CTAB in propylene glycol-water (30% v/v binary mixture, as well as the thermodynamic properties of the resulting micelles, were investigated by electrical conductivity measurements. The conductivity data were used to determine both the critical micellar concentration (CMC and the micellar ionization degree (α of CTin the temperature range 298.2-310.2 K. The equilibrium model of micelle formation was applied in order to obtain the thermodynamic parameters (the standard molar Gibbs free energy, ΔGm0, enthalpy, ΔHm0 and entropy, ΔSm0 of the micellization process. The values of DGm0 and DHm0 were found to be negative at all investigated temperatures, while the values of ΔSm0 were positive and became more positive as temperature increased. A linear dependence between ΔSm0 and ΔHm0, i.e. an enthalpy-entropy compensation effect, was observed. [Projekat Ministarstva nauke Republike Srbije, br. 172015
19. Natural Oxidation of Bromide to Bromine in Evaporated Dead Sea Brines
Science.gov (United States)
Gavrieli, Ittai; Golan, Rotem; Lazar, Boaz; Baer, Gidi; Zakon, Yevgeni; Ganor, Jiwchar
2016-04-01
Highly evaporated Dead Sea brines are found in isolated sinkholes along the Dead Sea. Many of these brines reach densities of over 1.3 kg/L and pHacidic with a value of ~6.3. In comparison, seawater with the same alkalinity would have a pH value well above 8.3, meaning that H+ activity is 100 fold lower than that of Dead Sea brine. In the present work we assess the apparent dissociation constant value of boric acid (K`B) for the Dead Sea brine and use it to explain the brine's low pH value. We then show that pH decreases further as the brine evaporates and salinity increases. Finally we explain the reddish hue of the hypersaline brines in the sinkholes as due to the presence of dissolved bromine. The latter is the product of oxidation of dissolved bromide, a process that is enabled by the low pH of the hypersaline brines and their high bromide concentration.
20. Modelling of a Tracer experiment (Bromide) at the lysimeter Wagna/Austria with MIKE-SHE
Science.gov (United States)
Reszler, Christian; Fank, Johann
2015-04-01
Data of a tracer experiment with Bromide at one of the three lysimeters in Wagna/Austria are used to test the unsaturated zone solute transport model in MIKE-SHE. On April 4th, 2005 50 mg/l of Bromide were applied on the lysimeter operated with conventional farming. At this time the lysimeter was covered with bare soil until the start of the cultivation of pumpkin one month later. Concentrations at the lysimeter bottom (180 cm depth) were measured and, after break-through, plant uptake was measured to quantify mass recovery. The model using the Richards-Van Genuchten-Mualem approach is setup by comprehensive data of vegetation and soil hydraulic properties available at the lysimeter. Water movement simulation in the unsaturated zone is tested against measured seepage rates at the lysimeter bottom and soil water contents in different soil depths in a period of five years. A sensitivity study shows that, particularly in the quaternary gravel zone two different parameter sets are necessary to represent the different dynamics of water content and seepage. With both two sets the general dynamics of the tracer experiment are simulated well. However, the early rapid rise of the measured concentrations could not be represented by either parameter set, which indicates a complex pore system consisting of different flow paths in the gravel zone, e.g., a system of matrix flow and macro-pore flow.
1. Modeling Water Flow and Bromide Transport in a Two-Scale-Structured Lignitic Mine Soil
Science.gov (United States)
Dusek, J.; Gerke, H. H.; Vogel, T.; Maurer, T.; Buczko, U.
2008-12-01
Two-dimensional single- and dual-permeability simulations are used to analyze water and solute fluxes in heterogeneous lignitic mine soil at a forest-reclaimed mine spoil heap. The soil heterogeneity on this experimental site "Barenbrucker Hohe" resulted from inclined dumping structures and sediment mixtures that consist of sand with lignitic dust and embedded lignitic fragments. Observations on undisturbed field suction- cell lysimeters including tracer experiments revealed funneling-type preferential flow with lateral water and bromide movement along inclined sediment structures. The spatial distribution of soil structures and fragment distributions was acquired by a digital camera and identified by a supervised classification of the digital profile image. First, a classical single-domain modeling approach was proposed with spatially variable scaling factors inferred from image analyses. In the next step, a two-continuum scenario was constructed to examine additional effects of nonequilibrium on the flow regime. The scaling factors used for the preferential flow domain are here obtained from the gradient of the grayscale images. So far, the single domain scenarios failed to predict the bromide leaching patterns although water effluent could be described. Dual-permeability model allows the incorporation of structural effects and can be used as a tool to further testing other approaches that account for structure effects. The numerical study suggests that additional experiments are required to obtain better understanding of the highly complex transport processes on this experimental site.
2. Pressure-Induced Structural and Optical Properties of Organometal Halide Perovskite-Based Formamidinium Lead Bromide.
Science.gov (United States)
Wang, Lingrui; Wang, Kai; Zou, Bo
2016-07-01
Organometal halide perovskites (OMHPs) are attracting an ever-growing scientific interest as photovoltaic materials with moderate cost and compelling properties. In this Letter, pressure-induced optical and structural changes of OMHP-based formamidinium lead bromide (FAPbBr3) were systematically investigated. We studied the pressure dependence of optical absorption and photoluminescence, both of which showed piezochromism. Synchrotron X-ray diffraction indicated that FAPbBr3 underwent two phase transitions and subsequent amorphization, leading directly to the bandgap evolution with redshift followed by blueshift during compression. Raman experiments illustrated the high pressure behavior of organic cation and the surrounding inorganic octahedra. Additionally, the effect of cation size and the different intermolecular interactions between organic cation and inorganic octahedra result in the fact that FAPbBr3 is less compressible than the reported methylammonium lead bromide (MAPbBr3). High pressure studies of the structural evolution and optical properties of OMHPs provide important clues in optimizing photovoltaic performance and help to design novel OMHPs with higher stimuli-resistant ability. PMID:27321024
3. Acute hepatitis after starting pinaverium bromide in a patient taking mirtazapine.
Science.gov (United States)
Tak, Sandeep; Tak, Shubhanjali
2014-01-01
A 56-year-old man presented with chronic abdominal pain. He had been evaluated extensively in the recent past undergoing upper gastrointestinal endoscopy, colonoscopy and CT scan of the abdomen with normal results. The provisional diagnosis of irritable bowel syndrome was performed and pinaverium bromide was started. The patient had pre-existing hypertension, a major depressive disorder and gastro-oesophageal reflux disease. He had been taking nebivolol and pantoprazole for several years and mirtazapine for the last 1 year. The patient developed nausea, vomiting and anorexia after 5 days of starting pinaverium bromide. Investigations revealed marked elevation of liver enzymes and bilirubin. He was negative for HIV, HBSAg, anti-hepatitis C virus, IgM for hepatitis A virus, hepatitis E virus, antinuclear antibody and antimitochondrial antibody. An ultrasound showed mild hepatomegaly with hypoechoic echo texture; the rest of scan was normal. Pinaverium and mirtazapine were stopped immediately. The patient was treated symptomatically and his liver profile returned to normal after 4 weeks. PMID:25015163
4. The influence of nitrogen oxides on the activation of bromide and chloride in salt aerosol
Science.gov (United States)
Bleicher, S.; Buxmann, J. C.; Sander, R.; Riedel, T. P.; Thornton, J. A.; Platt, U.; Zetzsch, C.
2014-04-01
Experiments on salt aerosol with different salt contents were performed in a Teflon chamber under tropospheric light conditions with various initial contents of nitrogen oxides (NOx = NO + NO2). A strong activation of halogens was found at high NOx mixing ratios, even in samples with lower bromide contents such as road salts. The ozone depletion by reactive halogen species released from the aerosol, was found to be a function of the initial NOx mixing ratio. Besides bromine, large amounts of chlorine have been released in our smog chamber. Time profiles of the halogen species Cl2, Br2, ClNO2, BrNO2 and BrO, ClO, OClO and Cl atoms were simultaneously measured by various techniques (chemical ionization mass spectrometry, differential optical absorption spectrometry coupled with a multi-reflection cell and gas chromatography of hydrocarbon tracers for Cl and OH, employing cryogenic preconcentration and flame ionization detection). Measurements are compared to calculations by the CAABA/MECCA 0-D box model, which was adapted to the chamber conditions and took the aerosol liquid water content and composition into account. The model results agree reasonably with the observations and provide important information about the prerequisites for halogen release, such as the time profiles of the aerosol bromide and chloride contents as well as the aerosol pH.
5. The application of activation analysis for the control of bromide accumulation in vegetable
International Nuclear Information System (INIS)
Soil desinfestation with methyl bromide increases the uptake of bromine by plants. The natural bromine content of crops and fruits was found in the range of 1 up to 5 ppm in fresh weight. The highest acceptable level is 50 ppm in fresh weight. By using methyl bromide as a soil fumigant, a bromine accumulation was found in the crops to levels up to 20-500 ppm in fresh matter. The uptake of bromine differs in various parts of the vegetable crops. The highest bromine concentration could be observed in the leaves. The bromine uptake by plants depends on (a) the fumigation technique (applied amounts, reaction time, date of cultivation); (b) the growing conditions (soil type, climate and irrigation); (c) the plants (species, rotation, harvesting time etc.). The INAA is a simple and rapid method to analyse bromine in vegetables within a wide range using Br-80 and Br-82. Since several years this method has also been used to control imported crops. The samples were subjected to a short irradiation (1-3 minutes at 1013ncm-2sec-1). After the decay time of a few minutes the induced activity was measured with a Ge(Li) detector coupled to a multi-channel analyzer. The limit of detection varies between 0.1 and 0.5 ppm Br in fresh vegetable samples. (T.G.)
6. Bromide as a tracer for studying water movement and nitrate displacement in soils: comparison with stable isotope tracers; Bromid als Tracer zur Untersuchung der Wasserbewegung und der Nitratverlagerung in Boeden: Vergleich mit stabilisotopen Tracern
Energy Technology Data Exchange (ETDEWEB)
Russow, R.; Knappe, S. [UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Bad Lauchstaedt (Germany). Sektion Bodenforschung
1999-02-01
Tracers are an ideal means of studying water movement and associated nitrate displacement. Often bromide is preferred as a tracer because it is considered a representative tracer for water and because, being a conservative tracer (i.e. not involved in chemical and biological soil processes), it can be used for studying anion transport in soils. Moreover, it is less expensive and easier to measure than the stable isotopes deuterium and {sup 15}N. Its great advantage over radioactive tracers (e.g. tritium), which outweighs their extreme sensitivity and ease of measurement and which it has in common with stable isotopes, is that it does not require radiation protection measures. However, there are also constraints on the use of bromide as a tracer in soil/water/plant systems. Our own studies on different soils using D{sub 2}O, bromide and [{sup 15}N]-nitrate in lysimeters suggest that the above assumptions on bromide tracers need not always be valid under conditions as they prevail in biologically active soils. As the present paper shows, these studies permit a good assessment of the possibilities and limits to these tracers. [Deutsch] Fuer die Untersuchung der Wasserbewegung sowie der daran gekoppelten Nitrat-Verlagerung ist der Einsatz von Tracern das Mittel der Wahl. Dabei wird Bromid als Tracer haeufig bevorzugt, da es allgemein als ein repraesentativer Tracer fuer Wasser und als konservativer Tracer (nicht involviert in chemische und biologische Bodenprozesse) zur Untersuchung des Anionentransportes in Boeden angesehen wird und es gegenueber den stabilen Isotopen Deuterium und {sup 15}N billiger und einfacher zu bestimmen ist. Gegenueber den radioaktiven Tracern (z.B. Tritium), die zwar sehr empfindlich und einfach messbar sind, besteht der grosse Vorteil, dass, wie bei den stabilen Isotopen, keine Strahlenschutzmassnahmen ergriffen werden muessen. Es gibt jedoch auch einschraenkende Hinweise fuer die Verwendung von Bromid als Tracer im System Boden
7. The Research on Programmable Control System of Lithium-Bromide Absorption Refrigerating Air Conditioner Based on the Network
Directory of Open Access Journals (Sweden)
Sun Lunan
2016-01-01
Full Text Available This article regard the solar lithium-bromide absorption refrigerating air conditioning system as the research object, and it was conducting adequate research of the working principle of lithium bromide absorption refrigerating machine, also it was analyzing the requirements of control system about solar energy air conditioning. Then the solar energy air conditioning control system was designed based on PLC, this system was given priority to field bus control system, and the remote monitoring is complementary, which was combining the network remote monitoring technology. So that it realized the automatic control and intelligent control of new lithium bromide absorption refrigerating air conditioning system with solar energy, also, it ensured the control system can automatically detect and adjust when the external conditions was random changing, to make air conditioning work effectively and steadily, ultimately ,it has great research significance to research the air conditioning control system with solar energy.
8. Combination of ozonation and photocatalysis for purification of aqueous effluents containing formic acid as probe pollutant and bromide ion.
Science.gov (United States)
Parrino, F; Camera-Roda, G; Loddo, V; Palmisano, G; Augugliaro, V
2014-03-01
The treatment by advanced oxidation processes (AOPs) of waters contaminated by organic pollutants and containing also innocuous bromide ions may generate bromate ions as a co-product. In the present work heterogeneous photocatalysis and ozonation have individually been applied and in combination (integrated process) to degrade the organic compounds in water containing also bromide anions. The results show that: i) the sole photocatalysis does not produce bromate ions and in the case of its presence, it is able to reduce bromate to innocuous bromide ions; ii) the integration of photocatalysis and ozonation synergistically enhances the oxidation capabilities; and iii) in the integrated process bromate ions are not produced as long as some oxidizable organics are present.
9. [Effects of bromide and ferric ions on formation of tri-halomethanes during disinfection of drinking water by chlorine].
Science.gov (United States)
Zhu, Zhi-Liang; Wang, Jing; Ge, Yuan-Xin; Ma, Hong-Mei; Zhao, Jian-Fu
2007-06-01
Effects of bromide and ferric ions on the formation and distribution of tri-halomethanes (THMs) have been investigated. As disinfection by-product (DBP) model precursors of natural water, humic acid solutions were used and a series of experiments were conducted. The results showed that bromide in this reaction system not only contributed to the increase of brominated species, but also the total tri-halomethanes. When the concentration of Br(-) was 1.0 mg/L, the total amount of produced THMs reached to 270% of that without bromide ions. In the presence of bromide, ferric ions decreased the production of THMs at pH 6, but increased the production of THMs at pH 8, especially for the amount of tri-bromomethanes. When the concentration of Fe3+ was 5 mg/L, the amount of produced tri-bromomethanes had an increment of 54% (from 51.7 microg/L to 79.4 microg/L), and the total amount of THMs increased from 113.49 microg/L to 162.09 microg/L. Bromide ions had a significant effect on carcinogenicity risk in disinfection of drinking water by chlorine, and the co-existence of ferric ion and bromide in alkalescent environment can result in the biggest challenge on carcinogenicity risk. Under the condition of 0.2 mg/L Br(-), 5 mg/L Fe3+ and pH 6, the carcinogenicity risk increased 2.5 times than that without Br(-) and Fe3+, and much higher increment of 5.1 times appeared when pH was 8.
10. Actinide Oxidation State and O/M Ratio in Hypostoichiometric Uranium-Plutonium-Americium U0.750Pu0.246Am0.004O2-x Mixed Oxides.
Science.gov (United States)
Vauchy, Romain; Belin, Renaud C; Robisson, Anne-Charlotte; Lebreton, Florent; Aufore, Laurence; Scheinost, Andreas C; Martin, Philippe M
2016-03-01
Innovative americium-bearing uranium-plutonium mixed oxides U1-yPuyO2-x are envisioned as nuclear fuel for sodium-cooled fast neutron reactors (SFRs). The oxygen-to-metal (O/M) ratio, directly related to the oxidation state of cations, affects many of the fuel properties. Thus, a thorough knowledge of its variation with the sintering conditions is essential. The aim of this work is to follow the oxidation state of uranium, plutonium, and americium, and so the O/M ratio, in U0.750Pu0.246Am0.004O2-x samples sintered for 4 h at 2023 K in various Ar + 5% H2 + z vpm H2O (z = ∼15, ∼90, and ∼200) gas mixtures. The O/M ratios were determined by gravimetry, XAS, and XRD and evidenced a partial oxidation of the samples at room temperature. Finally, by comparing XANES and EXAFS results to that of a previous study, we demonstrate that the presence of uranium does not influence the interactions between americium and plutonium and that the differences in the O/M ratio between the investigated conditions is controlled by the reduction of plutonium. We also discuss the role of the homogeneity of cation distribution, as determined by EPMA, on the mechanisms involved in the reduction process. PMID:26907589
11. Characterization of the corrosion products formed on mild steel in acidic medium with N-octadecylpyridinium bromide as corrosion inhibitor
Energy Technology Data Exchange (ETDEWEB)
Nava, N., E-mail: tnava@imp.mx; Likhanova, N. V. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Olivares-Xometl, O. [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria Quimica (Mexico); Flores, E. A. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Lijanova, I. V. [CIITEC, Instituto Politecnico Nacional (Mexico)
2011-11-15
The characterization of the corrosion products formed on mild steel SAE 1018 after 2 months exposure in aqueous sulfuric acid with and without corrosion inhibitor N-octadecylpyridinium bromide has been carried out by means of transmission {sup 57}Fe Moessbauer spectroscopy and X-ray powder diffraction (XRD). The major constituent of the rust formed in this environment without corrosion inhibitor is goethite ({alpha}-FeOOH). The samples with N-octadecylpyridinium bromide contain rozenite and large amounts of melanterite in the corrosion layers.
12. Enhanced Degradation of the Volatile Fumigant-Nematicides 1,3-D and Methyl Bromide in Soil
OpenAIRE
Ou, L.-T.
1998-01-01
The use of the gaseous funaigant-nematicide methyl bromide in agriculture is scheduled to be phased out in the year 2001.1,3-Dichloropropene (1,3-D) in combination with chloropicrin and an herbicide is considered to be a viable alternative to methyl bromide for some crops. 1,3-Dichloropropene consists of two isomers, cis- and trans-l,3-D. A number of soil bacteria have been shown to initially degrade 1,3-D or one of its isomers, cis-l,3-D, via hydrolysis. Until recently, the degradation of ci...
13. Characterization of the corrosion products formed on mild steel in acidic medium with N-octadecylpyridinium bromide as corrosion inhibitor
International Nuclear Information System (INIS)
The characterization of the corrosion products formed on mild steel SAE 1018 after 2 months exposure in aqueous sulfuric acid with and without corrosion inhibitor N-octadecylpyridinium bromide has been carried out by means of transmission 57Fe Mössbauer spectroscopy and X-ray powder diffraction (XRD). The major constituent of the rust formed in this environment without corrosion inhibitor is goethite (α-FeOOH). The samples with N-octadecylpyridinium bromide contain rozenite and large amounts of melanterite in the corrosion layers.
14. Spectral and Non Radiative Decay Studies of Lead Di Bromide Single Crystals by Mode Matched Thermal Lens Technique.
Science.gov (United States)
Rejeena, I; Lillibai, B; Thomas, V; Nampoori, V P N; Radhakrishnan, P
2016-07-01
In the present paper, the investigations on the non radiative decay mechanism, optical band gap determination from absorption spectroscopic studies and fluorescence emission by photo luminescence techniques using different excitation wavelengths on gel derived lead di bromide single crystals are reported. Non radiative decay of the sample is studied using high sensitive dual beam mode matched thermal lens technique. For the thermal lensing experiment the crystal in solution phase is incorporated with rhodamine 6G dye for enhancing the absorption of the crystal sample. The thermal diffusivity of lead di bromide is determined using the probe beam intensity v/s time measurements. PMID:27165040
15. Protective effect of testosterone on cognitive deficits induced by ethidium bromide in experimental model of multiple sclerosis
Directory of Open Access Journals (Sweden)
2015-11-01
Full Text Available Background: Multiple Sclerosis (MS is a neurodegenerative disease of the central nervous system (CNS. The hippocampus is a vital center for learning and memory; it is extremely vulnerable to neurodegenerative diseases. The male hormones could be neuroprotective for the CNS. The current study is an attempt to investigate the effect of testosterone on learning and spatial memory following the demyelination of CA1 area by the injection of ethidium bromide in the rats' hippocampus. Methods: This experimental study has been conducted on healthy rats in the faculty of science of the Urmia University from September 2013 to February 2015. For demyelination in all previously gonadectomized healthy rats, 3µl ethidium bromide was injected into the CA1 area of rats by stereotaxic surgery. In addition, the treatment groups received 1µl testosterone (6µg/µl during a 20-day timeframe on a daily basis after demyelination by the ethidium bromide. The control groups had no drug injection. The process of the learning and spatial memory of the rats were closely monitored by the radial Maze. The demyelination and remyelination in the hippocampus were checked by the myelin-specific coloring (Luxol fast blue and Cresyl violet. Results: The histological results suggest that the testosterone is capable of minimizing the destructive impacts of ethidium bromide in the treatment group as well as enhancing the remyelination process. In the group treated by testosterone, the percentage of the pyknotic cells 20 days after demyelination induction, represented a significant reduction compared to that of ethidium bromide group (P=0.008. The behavioral studies analyses show that the amount of the food finding time in those groups received ethidium bromide was significantly longer than those of the control groups (P=0.001. Furthermore, the application of the testosterone in the treatment groups reduced the extent of demyelination while the memory impairment induced by the
16. Physicochemical and thermodynamic characterization of N-alkyl-N-methylpyrrolidinium bromides and its aqueous solutions
Energy Technology Data Exchange (ETDEWEB)
2014-08-10
Highlights: • The aqueous solutions of bromide-based ionic liquids have been studied. • The synthesis and basic thermal characterization of pure IL have been done. • The density, dynamic viscosity, SLE and VLE have been determined. • The experimental data have been correlated using appropriate equations. - Abstract: This work is a continuation of our research of ionic liquids to investigate the physicochemical and thermodynamic properties of (ionic liquid + water) binary mixtures as a novel alternative working pair for the absorption heat pump cycle. In this work, a series of organic salts: N-propyl-N-methyl-pyrrolidinium bromide, [C{sub 1}C{sub 3}PYR]Br; N-butyl-N-methylpyrrolidinium, [C{sub 1}C{sub 4}PYR]Br and N-pentyl-N-methylpyrrolidinium bromide, [C{sub 1}C{sub 5}PYR]Br have been synthesized. The structures of new compounds have been confirmed using NMR spectra and elementary analysis. The basic thermal characterization of pure ILs, including temperature and enthalpy of phase transition (T{sub tr}, Δ{sub tr}H), temperature and enthalpy of melting (T{sub m,} Δ{sub m}H) have been measured using a differential scanning microcalorimetry technique (DSC). Decomposition temperature of the tested ILs were detected by the simultaneous TG/DTA experiments. The effect of temperature on the density (ρ) and dynamic viscosity (η) is reported over a wide temperature range from 298.15 to 343.15 K at ambient pressure. From experimental density data, the excess molar volumes (V{sup E}) were calculated and correlated using Redlich–Kister equation. The isothermal vapour–liquid phase equilibria (VLE) have been measured by an ebulliometric method at wide temperature range from 328.15 to 368.15 K and pressure up to 85 kPa. Experimental data have been correlated by means of NRTL equation. The solid–liquid phase equilibria (SLE) for the tested binary mixtures have been determined over whole composition range using dynamic method. The NRTL equation using parameters
17. Nanosized sustained-release pyridostigmine bromide microcapsules: process optimization and evaluation of characteristics
Directory of Open Access Journals (Sweden)
Tan Q
2013-02-01
Full Text Available Qunyou Tan,1,* Rong Jiang,3,* Meiling Xu,2,4,* Guodong Liu,5,* Songlin Li,1 Jingqing Zhang21Department of Thoracic Surgery, Institute of Surgery Research, Daping Hospital, Third Military Medical University, 2Medicine Engineering Research Center, Chongqing Medical University, 3Stem Cells and Tissue Engineering Research, Chongqing Medical University, 4Department of Pharmacy, Chongqing Emergency Medical Center, 5Eighth Department, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, People’s Republic of China*These authors contributed equally to this workBackground: Pyridostigmine bromide (3-[[(dimethylamino-carbonyl]oxy]-1-methylpyridinium bromide, a reversible inhibitor of cholinesterase, is given orally in tablet form, and a treatment schedule of multiple daily doses is recommended for adult patients. Nanotechnology was used in this study to develop an alternative sustained-release delivery system for pyridostigmine, a synthetic drug with high solubility and poor oral bioavailability, hence a Class III drug according to the Biopharmaceutics Classification System. Novel nanosized pyridostigmine-poly(lactic acid microcapsules (PPNMCs were expected to have a longer duration of action than free pyridostigmine and previously reported sustained-release formulations of pyridostigmine.Methods: The PPNMCs were prepared using a double emulsion-solvent evaporation method to achieve sustained-release characteristics for pyridostigmine. The preparation process for the PPNMCs was optimized by single-factor experiments. The size distribution, zeta potential, and sustained-release behavior were evaluated in different types of release medium.Results: The optimal volume ratio of inner phase to external phase, poly(lactic acid concentration, polyvinyl alcohol concentration, and amount of pyridostigmine were 1:10, 6%, 3% and 40 mg, respectively. The negatively charged PPNMCs had an average particle size of 937.9 nm
18. An innovative experimental design reveals the spatial correlation between landuse, irrigation properties, and bromide leaching
Science.gov (United States)
Schwen, A.; Yang, Y.; Walton, J.; Wendroth, O.
2012-04-01
Understanding the relationship between leaching of pesticides and soil hydraulic properties under different land use conditions is critical to our understanding of the flow of water and solutes in soils and efforts to model these flow characteristics. One problem inherent in the measurement of solute leaching in field experiments is the considerable high natural spatial variability of flow-controlling soil properties. Thus, analyzing treatment effects based on the mean and the variance of observations can become obsolete if there is a huge inherent variance in the set of measurements. Moreover, no spatial range of influence can be derived from the observations. To overcome this limitation, the spatial covariance and cross-variance between measurements was used as decision and quality criteria in the present study. This study aims to demonstrate that focussing on the spatial covariance of observations and considering their spatial process can provide a measure of spatial representativity or scale-specific variance. We introduce a novel experimental scheme, where the treatments are arranged in a scale-dependent manner. In a field trial in Lexington, Kentucky, bromide leaching under two contrasting land use systems (no-till agricultural crops vs. pasture) was compared. After surface application of tracer solution (KBr), the experimental field was irrigated using different time-delays (1, 4 and 24 hours) as well as two different irrigation amounts and two different intensities. At the end, the KBr-concentration in the soil profile was determined using auger samplings. The data was correlated with the applied boundary conditions by spatial statistical methods such as semivariograms, cross-semivariograms and spectral analysis. Our results show distinct differences in the leaching behaviour between the two analyzed land uses with an deeper infiltration in the no-till agricultural field. This can be partly related to a higher initial soil water content in this treatment
19. COPD patient satisfaction with ipratropium bromide/albuterol delivered via Respimat: a randomized, controlled study
Directory of Open Access Journals (Sweden)
Ferguson GT
2013-03-01
Full Text Available Gary T Ferguson,1 Mo Ghafouri,2 Luyan Dai,2 Leonard J Dunn31Pulmonary Research Institute of Southeast Michigan, Livonia, MI, USA; 2Boehringer Ingelheim Pharmaceuticals, Inc, Ridgefield, CT, USA; 3Clinical Research of West Florida, Inc, Clearwater, FL, USABackground: Ipratropium bromide/albuterol Respimat inhaler (CVT-R was developed as an environmentally friendly alternative to ipratropium bromide/albuterol metered-dose inhaler (CVT-MDI, which uses a chlorofluorocarbon propellant.Objective: The objective of this study was to evaluate patient satisfaction, device usage, and long-term safety of CVT-R compared to CVT-MDI, and to the simultaneous administration of ipratropium bromide hydrofluoroalkane (HFA; I and albuterol HFA (A metered-dose inhalers as dual monotherapies (I + A.Design: This is a 48-week, open-label, randomized, active-controlled, parallel-group study (n = 470 comparing CVT-R to CVT-MDI and to I + A.Participants: Patients were at least 40 years of age, diagnosed with chronic obstructive pulmonary disease (COPD, and current or exsmokers.Interventions: Patients were randomized to receive: (1 CVT-R, one inhalation four times daily (QID; or (2 CVT-MDI, two inhalations QID; or (3 I + A two inhalations of each inhaler QID.Main measures: Patient Satisfaction and Preference Questionnaire (PASAPQ performance score (primary endpoint and adverse events.Key results: PASAPQ performance score was significantly higher (CVT-R versus CVT-MDI, 9.6; and CVT-R versus I + A, 6.2; both P < 0.001 when using CVT-R compared to CVT-MDI or I + A at all visits starting from week 3, while CVT-MDI and I + A treatment groups were similar. Time to first COPD exacerbation was slightly longer in the CVT-R group compared to the other treatment groups, although it did not reach statistical significance (CVT-R versus CVT-MDI, P = 0.57; CVT-R versus I + A, P = 0.22. Rates of withdrawal and patient refusal to continue treatment were lower in CVT-R compared with CVT
20. Copper-catalysed N-arylation of arylsulfonamides with aryl bromides and aryl iodides using KF/Al2O3
2010-03-01
An efficient synthesis of -arylsulfonamides with a variety of aryl bromides, aryl iodides and heteroaryl bromides using KF/Al2O3 as a suitable base, CuI as an inexpensive catalyst and ,'-dimethylethylenediamine (,'-DMEDA) as an effective ligand is described.
1. Carbon nanotubes as an efficient hole collector for high voltage methylammonium lead bromide perovskite solar cells.
Science.gov (United States)
Li, Zhen; Boix, Pablo P; Xing, Guichuan; Fu, Kunwu; Kulkarni, Sneha A; Batabyal, Sudip K; Xu, Wenjing; Cao, Anyuan; Sum, Tze Chien; Mathews, Nripan; Wong, Lydia Helena
2016-03-28
A high open circuit voltage (V(OC)) close to 1.4 V under AM 1.5, 100 mW cm(-2) conditions is achieved when carbon nanotubes (CNTs) are used as a hole conductor in methyl ammonium lead bromide (MAPbBr3) perovskite solar cells. Time-resolved photoluminescence and impedance spectroscopy investigations suggest that the observed high V(OC) is a result of the better charge extraction and lower recombination of the CNT hole conductor. Tandem solar cells with all perovskite absorbers are demonstrated with a MAPbBr3/CNT top cell and a MAPbI3 bottom cell, achieving a V(OC) of 2.24 V in series connection. The semitransparent and high voltage MAPbBr3/CNT solar cells show great potential for applications in solar cell windows, tandem solar cells and solar driven water splitting. PMID:26646241
2. Increase in mitotic recombination in diploid cells of Aspergillus nidulans in response to ethidium bromide
Directory of Open Access Journals (Sweden)
Tânia C.A. Becker
2003-01-01
Full Text Available Ethidium bromide (EB is an intercalating inhibitor of topoisomerase II and its activities are related to chemotherapeutic drugs used in anti-cancer treatments. EB promotes several genotoxic effects in exposed cells by stabilising the DNA-enzyme complex. The recombinagenic potential of EB was evaluated in our in vivo study by the loss of heterozygosity of nutritional markers in diploid Aspergillus nidulans cells through Homozygotization Index (HI. A DNA repair mutation, uvsZ and a chromosome duplication DP (II-I were introduced in the genome of tested cells to obtain a sensitive system for the recombinagenesis detection. EB-treated diploid cells had HI values significantly greater than the control at both concentrations (4.0 x 10-3 and 5.0 x 10-3 mM. Results indicate that the intercalating agent is potentially capable of inducing mitotic crossing-over in diploid A. nidulans cells.
3. Behavior of aqueous Tetrabutylammonium bromide - a combined approach of microscopic simulation and neutron scattering
CERN Document Server
Bhowmik, Debsindhu
2016-01-01
Aqueous solution of tetrabutylammonium bromide is studied by quasi-elastic neutron scattering, to give information on the dynamic modes involving the ions present. Using a careful combination of two techniques, time-of-flight (TOF) and neutron spin echo (NSE), we de- couple the dynamic information in both the coherently and incoherently scattered signal from this system. We take advantage of the different intensity ratio of the two signals, as detected by each of the techniques, to achieve this decoupling. By using heavy water as the sol- vent, the tetrabutylammonium cation is the only hydrogen-containing species in the system and gives rise to a significant incoherent scattered intensity. The dynamic analysis of the incoherent signal (measured by TOF) leads to a translational diffusion coefficient of the cation as that is in good agreement with previous NMR, neutron scattering and tracer diffusion measurements. The dynamic analysis of the coherent signal observed at wave-vectors < 0.6 angstrom^(-1) (measu...
4. Copper bromide vapor brightness amplifiers with 100 kHz pulse repetition frequency
Science.gov (United States)
Trigub, M. V.; Evtushenko, G. S.; Torgaev, S. N.; Shiyanov, D. V.; Evtushenko, T. G.
2016-10-01
The paper presents a laser monitor with 10 μs time-resolution based on a high-frequency copper bromide vapor brightness amplifier. A sync circuit has been designed for single-pulse imaging. The analysis of amplifying characteristics of the active elements and active optical system (laser monitor) parameters allowed to determine the optimal concentration of HBr at which the images can be obtained with minimum distortions. For the active element operating at high frequencies (more than 50 kHz) as a brightness amplifier, the concentration of HBr must be lower than that needed for obtaining the maximum output power. The limiting brightness temperature of the background radiation which does not affect the image quality is determined. The potential feasibility of using a proposed brightness amplifier for visualizing processes blocked from viewing by the background radiation with the brightness temperature up to 8000 K is demonstrated.
5. Spectroscopic study one thiosemicarbazone derivative with ctDNA using ethidium bromide as a fluorescence probe.
Science.gov (United States)
Geng, Shaoguang; Wu, Qing; Shi, Lei; Cui, Fengling
2013-09-01
In this study, a thiosemicarbazone derivative (E)-2-((1,4-dihydroxy-9,10-anthraquinone-2-yl)methylene)-N-(4-fluorophenyl)hydrazinecarbothioamide (DAFPT) was synthesized, and the interaction of DAFPT with calf thymus DNA (ctDNA) was explored using ethidium bromide (EB) as a fluorescence probe. The binding mode between DAFPT and ctDNA was investigated by UV absorption spectroscopy, fluorescence spectroscopy and molecular docking. The fluorescence quenching mechanism of EB-ctDNA by DAFPT might be a combined quenching type. Thermodynamic parameters showed that the reaction was spontaneous. According to ionic strength, fluorescence polarization and melting temperature (T(m)) curve results, DAFPT-ctDNA interaction was groove binding. The molecular modeling results indicated that DAFPT could slide into the A-T rich region of ctDNA. PMID:23769721
6. Lithium bromide absorption machines: Pressure drop and mass transfer in solutions conical sheets
Energy Technology Data Exchange (ETDEWEB)
Palacios, E. [Escuela Universitaria de Ingenieria Tecnica Industrial, U.P.M., Ronda de Valencia 3, Madrid 28012 (Spain); Izquierdo, M. [Instituto de Ciencias de la Construccion Eduardo Torroja. C.S.I.C., Serrano Galvache 4, Madrid 28033 (Spain); Lizarte, R. [Escuela Politecnica Superior, Universidad Carlos III de Madrid, Avda. de la Universidad 30, Madrid 28911 (Spain); Marcos, J.D. [Escuela Tecnica Superior de Ingenieria Industrial, U.N.E.D., Juan del Rosal 12, Madrid 28040 (Spain)
2009-07-15
Adiabatic vapour absorption in conical liquid sheets is studied with a view to use in air conditioning. The sheets consist in a lithium bromide aqueous solution sprayed at mass flow rates ranging from 0.0078 to 0.0116 kg/s (28-42 kg/h). The experimental results show that the deformation rate associated with conical sheet development has a significant effect on absorption, with 60% of the total reached by the time the liquid sheet disintegrates, 4 ms after injection. In the conical sheet configuration, about 150 g of vapour are absorbed per kJ of solution flow work. The vapour absorption rate per chamber absorption volume, in turn, is found to be over 1 g/s l in absorption chambers 75 mm long or less. (author)
7. [Investigation of the oxidation reaction of O3 with bromide ion in aqueous solution].
Science.gov (United States)
Yu, Xiao-Ting; Zhang, Jia-Hui; Pan, Xun-Xi; Zhang, Ren-Xi; Hou, Hui-Qi
2012-09-01
The reaction mechanism of O3 with bromide ion in aqueous solution was studied by ion chromatography and UV-Vis spectrometry instruments. Ion chromatography analysis showed that only 10% of Br- which was oxidized by ozone was formed into bromate ion. The results demonstrated that the final products of the oxidation reaction were identified as Br2 and Br3- except for BrO3-. The formation of Br3- which was yielded from the reaction of Br2 with Br- was the major process in the reaction of Br attacked by O3. The characteristic absorption spectrum of Br3- with an absorption peak at 260 nm was also investigated. The results may provide helpful information about the mechanism of the oxidation reaction of Br- with O3 and fate of Br- or its derivatives in the environment by the oxidation processes.
8. 2-(4-Methylsulfanylphenyl-1H-benzimidazol-3-ium bromide
Directory of Open Access Journals (Sweden)
Mohamed Ziaulla
2011-02-01
Full Text Available In the cation of the title compound, C14H13N2S+·Br−, the essentially planar benzimidazole system (r.m.s. deviation = 0.0082 Å is substituted with a 4-methylsulfanylphenyl ring. The dihedral angle between the benzimidazole system and the 4-methylsulfanylphenyl ring is 2.133 (2°. The crystal structure is characterized by strong and highly directional intermolecular N—H...Br hydrogen bonds involving the bromide ion. Moreover, C—H...S interactions result in chains of molecules along the c axis. The supramolecular assembly is further stabilized by π–π stacking interactions between the benzimidazole system and 4-methylsulfanylphenyl rings [centroid–centroid distance = 3.477 (4 Å].
9. Solubilization Using Some Novel N-Methyl Diethanolammonium Bromide Cationic Surfactants
International Nuclear Information System (INIS)
A novel series of N-methyl diethanolammonium bromide cationic surfactants was used as solubilizing agent for nonpolar substrate (paraffin oil) at 25 degree C. The results of solubilization measurements showed good ability for the used surfactants towards solubilizing paraffin oil in aqueous medium. The results showed also, that the chemical structure of the soluble plays an important rule in its solubilization. Several factors were found to influence the extent of solubilization, which are: number of alkyl chains within surfactant molecule, symmetry of molecules and chain length of hydrophobic parts. The results were rationalized by the Kraft point and HLB values of the used surfactants. Furthermore, solubilization curves showed the steady state solubilization of each surfactant used
10. Improved hydrogen evolution on glassy carbon electrode modified with novel Pt/cetyltrimethylammonium bromide nanoscale aggregates
Institute of Scientific and Technical Information of China (English)
Jahan-Bakhsh Raoof; Sayed Reza Hosseini; Seyedeh Zeinab Mousavi-Sani
2015-01-01
A novel, cost‐effective, and simple electrocatalyst based on a Pt‐modified glassy carbon electrode (GCE), using cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, is reported. Am‐phiphilic CTAB molecules were adsorbed on GCE by immersion in a CTAB solution. The positively charged hydrophilic layer, which consisted of small aggregates of average size less than 100 nm, was used for accumulation and complexation of [PtCl6]2− anions by immersing the electrode in K2PtCl6 solution. The modified electrode was characterized using scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, impedance spectroscopy, and electrochemical methods. The electrocatalytic activity of the Pt particles in the hydrogen evolution reaction (HER) was investigat‐ed. The results show that the CTAB surfactant enhances the electrocatalytic activity of the Pt parti‐cles in the HER in acidic solution.
11. Flotation de-silicating from diasporic-bauxite with cetyl trimethylammonium bromide
Institute of Scientific and Technical Information of China (English)
王毓华; 胡岳华; 刘晓文
2003-01-01
Using cetyl trimethylammonium bromide (CTAB) as collector, the flotation de-silicating from diasporicbauxite was investigated. And the Zeta potentials and contact-angles of silicate minerals and diaspore were also stuite and illite become more positive, and the contact angles of these three silicates also increase evidently in the pH range of 2-8, but the Zeta potentials and contact angles of diaspore change little. So, the floatability of the four minerals is in the following order: pyrophyllite＞kaolinite≈illite＞diaspore. The open-circuit flotation results also show that a bauxite concentrate with m(Al2 O3 )/m(SiO2 ) over 9.3 and Al2 O3 recovery over 76% can be obtained from diasporic-bauxite ore. The result of XRD of the bauxite concentrate shows that pyrophyllite is easier to be removed from diasporic-bauxite than illite and kaolinite due to its better floatability.
12. Spectroscopic probe of the competitive binding of ethidium bromide and neomycin to DNA
Science.gov (United States)
Pal, Medini Kanta; Ghosh, Jimut Kanti
1995-03-01
The three spectroscopic changes of ethidium bromide (EB) on its binding to DNA, namely red-shift of the νmax, enhancement of fluorescence and induced dichroism are utilized to study the competitive binding of neomycin (NMC) and EB to DNA. Reversion of νmax, decrease in fluorescence and reduction of dichroism of DNA-EB on addition of NMC shows that the binding of NMC and EB to DNA is competitive in nature, over a limited concentration of the polymer. The binding constant of EB-DNA falls from 4.00 × 10 6 to 2.27 × 10 4 1 mol -1 in the presence of added NMC.
13. Successful treatment of migrating partial seizures in Wolf-Hirschhorn syndrome with bromide.
Science.gov (United States)
Itakura, Ayako; Saito, Yoshiaki; Nishimura, Yoko; Okazaki, Tetsuya; Ohno, Koyo; Sejima, Hitoshi; Yamamoto, Toshiyuki; Maegaki, Yoshihiro
2016-08-01
A girl with mild psychomotor developmental delay developed right or left hemiclonic convulsion at 10months of age. One month later, clusters of hemiclonic or bilateral tonic seizures with eyelid twitching emerged, resulting in status epilepticus. Treatment with phenobarbital and potassium bromide completely terminated the seizures within 10days. Ictal electroencephalography revealed a migrating focus of rhythmic 3-4Hz waves from the right temporal to right frontal regions and then to the left frontal regions. Genetic analysis was conducted based on the characteristic facial appearance of the patient, which identified a 2.1-Mb terminal deletion on chromosome 4p. This is the first case of Wolf-Hirschhorn syndrome complicated by epilepsy with migrating partial seizures. PMID:26797656
14. The matlockite-type praseodymium(III oxide bromide PrOBr
Directory of Open Access Journals (Sweden)
Pia Talmon-Gros
2011-12-01
Full Text Available The crystal structure of the praseodymium(III oxide bromide, PrOBr, can be best described with layers of agglomerated square antiprisms [PrO4Br4]9−. These slabs are stacked along the c axis and linked via two different secondary contacts between Pr3+ and Br−. The Pr3+ cations occupy the Wyckoff site 2c with 4mm symmetry and carry four O2− anions as well as four primary Br− anions, yielding a coordination number of 8. While the Br− anions exhibit the same site symmetry as the Pr3+ cations, the oxide anions are located at the Wyckoff position 2a with site symmetry overline{4}m2 and have four Pr3+ cations as neighbours, defining a tetrahedron.
15. Bio-conjugated silver nanoparticles: from Ocimum sanctum and role of cetyltrimethyl ammonium bromide.
Science.gov (United States)
Zaheer, Zoya; Rafiuddin
2013-08-01
In this paper we have reported the spectrophotometeric and transmission electron microscopic (TEM) data to the shape-directing role of cetyltrimethylammonium bromide (CTAB) on the green extra-cellular synthesis of bio-conjugated Ag-nanoparticles using Ocimum sanctum leaves extract. TEM images revealed that the nanoparticles are mostly spherical (average particle size ranged from 18 to 35nm) with some truncated triangular nanoplates, aggregated in a beautiful manner to yield locket-like silver and capped by a thin layer of biomolecules of O. sanctum, whereas nanoparticles are highly poly-dispersed in presence of CTAB. The shape and position of wavelength maxima strongly depends on the reaction time, [leaves extract] and [CTAB]. The visual observations also suggest that the prefect transparent silver sol becomes turbid in presence of CTAB after some time. PMID:23524081
16. Synthesis and photoluminescence of semiconductor quantum dots/cetyltrimethylammonium bromide vesicle core/shell nanostructures
International Nuclear Information System (INIS)
The synthesis and photoluminescence properties of the SiC quantum dots (QDs)/cetyltrimethylammonium bromide (CTAB) multilayered vesicle core/shell nanostructures are reported. The Coulomb attraction force between the negatively charged surface of the QD and the positively charged ionized CTAB molecules drives the formation of the core/shell nanostructures. The outer CTAB molecules are demonstrated to form multilayered vesicles. The core/shell nanostructures exhibit strong near-UV photoluminescence which is supposed to stem from the outer CTAB vesicles. This novel semiconductor QD/vesicle core/shell structures can serve as a prototype for studying the QD–organic molecule interaction as well as the building block for constructing nanoscale devices.
17. Fluorescence studies on the interaction of ethidium bromide with duplex, triplex and quadruplex DNA structures
Institute of Scientific and Technical Information of China (English)
孙雪光; 曹恩华; 何裕建; 秦静芬
1999-01-01
Under different conditions, oligonucleotides can form several alternative DNA structures such as duplex, triplex and quadruplex. All these structures can interact with ethidium bromide (EB) and make its fluorescence intensity change. The fluorescence spectra and other related parameters provided by static fluorescence techniques showed that the interaction mechanisms between EB and these structures were not always the same. Among them, B type duplex and triplex DNA adopt an intercalative mode when binding to the EB, which has a relatively high efficiency of energy transfer and the fluorescence of EB cannot be quenched easily. While for the parallel duplex DNA, the interaction mode is an outside binding in which energy transfer can hardly happen and its fluorescence intensity as well as Stern-Volmer constant is almost the same to the free EB. For the quadruplex, the binding mechanism to EB is more complex. Results from the energy transfer and quenching studies indicate that the two interaction modes note
18. Suzuki Reaction of Aryl Bromides Using a Phosphine-Free Magnetic Nanoparticle-Supported Palladium Catalyst
Institute of Scientific and Technical Information of China (English)
Nghia T. BUI; Trung B. DANG; Ha V. LE; Nam T. S. PHAN
2011-01-01
A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g.The catalyst was characterized using X-ray diffraction,scanning electron microscopy,transmission electron microscopy,vibrating sample magnetometry,thermogravimetric analysis,Fourier transform infrared,atomic absorption spectrophotometry,and nitrogen adsorption.The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid.The recovery of catalyst was simply by magnetic decantation in the presence of a magnet.The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity.No leaching of active palladium species into the reaction solution was detected.
19. Tetrabutylammonium Bromide (TBABr-Based Deep Eutectic Solvents (DESs and Their Physical Properties
Directory of Open Access Journals (Sweden)
Rizana Yusof
2014-06-01
Full Text Available Density, viscosity and ionic conductivity data sets of deep eutectic solvents (DESs formed by tetrabutylammonium bromide (TBABr paired with ethlyene glycol, 1,3-propanediol, 1,5-pentanediol and glycerol hydrogen bond donors (HBDs are reported. The properties of DES were measured at temperatures between 303 K and 333 K for HBD percentages of 66.7% to 90%. The effects of HBDs under different temperature and percentages are systematically analyzed. As expected, the measured density and viscosity of the studied DESs decreased with an increase in temperature, while ionic conductivity increases with temperature. In general, DESs made of TBABr and glycerol showed the highest density and viscosity and the lowest ionic conductivity when compared to other DESs. The presence of an extra hydroxyl group on glycerol in a DES affected the properties of the DES.
20. Precipitation of silicic acid from geothermal water by addition of cetyl-trimethyl-ammonium bromide
Energy Technology Data Exchange (ETDEWEB)
Kitsuki, Harumi; Yokoyama, Takushi; Shimada, Kanichi; Yamanaka, Chiho; Nishu, Keisuke; Shimizu, Shin; Tarutani, Toshikazu
1986-01-25
Cetyl-trimethyl-ammonium bromide (CTAB) was added to sodium silicate solution and geothermal hot water (Ohtake Geothermal Power Plant and Hatchobaru Geo-thermal Power Plant) to precipitate silica. 1) CTA ions do not react with monosilicic acid, but only the polymerization among the polysilicic acids proceeds and causes silica to precipitate. Optimum pH for the silica precipitation is 6 - 7 and the higher concentration of polysilicic acid will cause more precipitation. 2) When added to geothermal hot water, the silica precipita-tion increases with the increase of CTAB concentration within the range of 10/sup -7/ - 10/sup -4/ mol dm/sup 3/ concentration. Almost all poly-silicic acid precipitated at 10/sup -4/ mol dm/sup 3/ when measured for silica precipitation after 5 minutes. Total concentration of silicic acid was higher in the Hatchobaru geothermal water than that of the Ohtake geothermal water. (10 figs, 14 refs)
1. INTERACTION OF POLY(SODIUM SULFODECYL METHACRYLATE) WITH CETYLTRIMETHYL AMMONIUM BROMIDE IN AQUEOUS SOLUTION
Institute of Scientific and Technical Information of China (English)
Cong-hua Lu; Chuan-qiou Luo; Wei-xiao Cao
2003-01-01
The interaction of poly(sodium sulfodecyl methacrylate) (PSSM) with cetyltrimethyl ammonium bromide (CTAB)was studied. It was found that the precipitate formed from PSSM and CTAB will be dissolved by excessive CTAB, resultingin the appearance of two maxima of the solution viscosity at the molar ratio (CTAB/-SO3-) of ≈ 0.68 and ≈ 1.30,respectively. The first one is related closely to the aggregation of polymer chains via CTAB molecules and the second oneshould be ascribed to the formation of the mixed micelles comprising surfactant and the polymer's hydrophobic chains. Theeffect of NaCl on the viscosity, the transmittance of the aqueous solution and the solubility of oil-soluble dye (dimethylyellow) in the mixed system were also investigated.
2. Direct electrochemistry and electrocatalysis of myoglobin in dodecyltrimethylammonium bromide film modified carbon ceramic electrode
Institute of Scientific and Technical Information of China (English)
Yuan Zhen Zhou; Hui Wang; She Ying Dong; An Xiang Tian; Zhi Xian He; Bin Chen
2011-01-01
Direct electrochemistry and electrocatalysis of myoglobin (Mb) were studied with Mb immobilized on dodecyltrimethylammonium bromide (DTAB) film modified carbon ceramic (CC) electrode. Cyclic voltammetry showed a pair of well-defined and nearly reversible redox peaks of Mb (FeⅡ/FeⅢ) at about -0.3 V vs. SCE (pH = 6.98). The currents of the redox peak were linear to scan rate, and rate constant (Ks) was estimated to be 3.03 s-1. The formal potential (E01) of Mb in the DTAB/CC electrodes shifted linearly with pH with a slope of-36.44 mV/pH, implying that the electron transfer between DTAB and CC electrodes is accompanied by proton transportation. The immobilized Mb exhibited excellent electrocatalytic response to the reduction of hydrogen peroxide (H2O2).
3. Multimetallic catalysed cross-coupling of aryl bromides with aryl triflates
Science.gov (United States)
Ackerman, Laura K. G.; Lovell, Matthew M.; Weix, Daniel J.
2015-08-01
The advent of transition-metal catalysed strategies for forming new carbon-carbon bonds has revolutionized the field of organic chemistry, enabling the efficient synthesis of ligands, materials, and biologically active molecules. In cases where a single metal fails to promote a selective or efficient transformation, the synergistic cooperation of two distinct catalysts--multimetallic catalysis--can be used instead. Many important reactions rely on multimetallic catalysis, such as the Wacker oxidation of olefins and the Sonogashira coupling of alkynes with aryl halides, but this approach has largely been limited to the use of metals with distinct reactivities, with only one metal catalyst undergoing oxidative addition. Here, we demonstrate that cooperativity between two group 10 metal catalysts--(bipyridine)nickel and (1,3-bis(diphenylphosphino)propane)palladium--enables a general cross-Ullmann reaction (the cross-coupling of two different aryl electrophiles). Our method couples aryl bromides with aryl triflates directly, eliminating the use of arylmetal reagents and avoiding the challenge of differentiating between multiple carbon-hydrogen bonds that is required for direct arylation methods. Selectivity can be achieved without an excess of either substrate and originates from the orthogonal reactivity of the two catalysts and the relative stability of the two arylmetal intermediates. While (1,3-bis(diphenylphosphino)propane)palladium reacts preferentially with aryl triflates to afford a persistent intermediate, (bipyridine)nickel reacts preferentially with aryl bromides to form a transient, reactive intermediate. Although each catalyst forms less than 5 per cent cross-coupled product in isolation, together they are able to achieve a yield of up to 94 per cent. Our results reveal a new method for the synthesis of biaryls, heteroaryls, and dienes, as well as a general mechanism for the selective transfer of ligands between two metal catalysts. We anticipate that this
4. Boron-doped diamond anodic oxidation of ethidium bromide: Process optimization by response surface methodology
International Nuclear Information System (INIS)
Highlights: ► Boron-doped diamond was used to degrade ethidium bromide. ► The process was optimized by a central composite rotatable design coupled with response surface methodology. ► Applied current is proved to be the most significant variable. ► A possible reaction sequence involving all the detected byproducts was proposed. - Abstract: The degradation of ethidium bromide (EtBr), a DNA intercalating pollutant, had been studied by anodic oxidation on boron-doped diamond (BDD) electrode under galvanostatic conditions. A central composite rotatable design coupled with response surface methodology was implemented to optimize the various operating parameters involved, among initial pH, flow rate, applied current and supporting electrolyte concentration, on the treatment efficiency; the latter was assessed in terms of color removal, COD removal, specific energy consumption and general current efficiency. Of the four parameters involved, applied current had a considerable effect on all the response factors. Optimum EtBr degradation was achieved by applying a current of 0.90 A, 9.0 mM Na2SO4, flow rate of 400 ml min−1 and pH 6.2 at 60 min of electrolysis, being reduced color by 80.2% and COD by 29.7%, with an energy consumption of 398.32 kW h (kg COD)−1 and a general current efficiency of 10.1%. Under these optimized conditions, EtBr decays followed pseudo first-order kinetics. Moreover, HPLC analysis of the BDD-treated solution allowed the detection of a number of reaction intermediates, and a possible reaction sequence involving all the detected byproducts was proposed for the electrochemical oxidation of EtBr on BDD anode.
5. Carbon nanotubes as an efficient hole collector for high voltage methylammonium lead bromide perovskite solar cells
Science.gov (United States)
Li, Zhen; Boix, Pablo P.; Xing, Guichuan; Fu, Kunwu; Kulkarni, Sneha A.; Batabyal, Sudip K.; Xu, Wenjing; Cao, Anyuan; Sum, Tze Chien; Mathews, Nripan; Wong, Lydia Helena
2016-03-01
A high open circuit voltage (VOC) close to 1.4 V under AM 1.5, 100 mW cm-2 conditions is achieved when carbon nanotubes (CNTs) are used as a hole conductor in methyl ammonium lead bromide (MAPbBr3) perovskite solar cells. Time-resolved photoluminescence and impedance spectroscopy investigations suggest that the observed high VOC is a result of the better charge extraction and lower recombination of the CNT hole conductor. Tandem solar cells with all perovskite absorbers are demonstrated with a MAPbBr3/CNT top cell and a MAPbI3 bottom cell, achieving a VOC of 2.24 V in series connection. The semitransparent and high voltage MAPbBr3/CNT solar cells show great potential for applications in solar cell windows, tandem solar cells and solar driven water splitting.A high open circuit voltage (VOC) close to 1.4 V under AM 1.5, 100 mW cm-2 conditions is achieved when carbon nanotubes (CNTs) are used as a hole conductor in methyl ammonium lead bromide (MAPbBr3) perovskite solar cells. Time-resolved photoluminescence and impedance spectroscopy investigations suggest that the observed high VOC is a result of the better charge extraction and lower recombination of the CNT hole conductor. Tandem solar cells with all perovskite absorbers are demonstrated with a MAPbBr3/CNT top cell and a MAPbI3 bottom cell, achieving a VOC of 2.24 V in series connection. The semitransparent and high voltage MAPbBr3/CNT solar cells show great potential for applications in solar cell windows, tandem solar cells and solar driven water splitting. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06177f
6. Thallium bromide chloride (TlBrxCl1-x) nuclear radiation detector
International Nuclear Information System (INIS)
Thallium bromide (TlBr) has been studied as an X- and gamma-ray detector material and relatively good spectrometric performances have been obtained from the detectors. However, the energy resolution of the TlBr detectors is limited by the relatively low resistivity of the crystals. Thallium bromide chloride (TlBrxCl1-x) is a mixed crystal of TlBr and thallium chloride (TlCl). TlBr0.8Cl0.2 crystals have been grown by the traveling molten zone method (TMZ) from purified materials. Nuclear radiation detectors have been fabricated from the grown TlBr0.8Cl0.2 crystals and the detector performance has been characterized. Optical transmittance was evaluated in order to characterize bandgap of the grown crystal. The results confirm that the bandgap of TlBr0.8Cl0.2 is wider than the bandgap of TlBr. Leakage currents of the detectors were measured as a function of the bias voltage at room temperature. The resistivity of the TlBr0.8Cl0.2 detector is approximately equal to the resistivity of typical TlBr detector. A TlBr0.8Cl0.2 detector operated at room temperature was irradiated with gamma-rays from 137Cs source. The detector exhibited a clear peak corresponding 662 keV gamma-rays. The resolution obtained by the TlBr0.8Cl0.2 detector, however, was presently not better than the resolution obtained by the typical TlBr detector. (M. Suetake)
7. Ethidium bromide transport across Mycobacterium smegmatis cell-wall: correlation with antibiotic resistance
Directory of Open Access Journals (Sweden)
Couto Isabel
2011-02-01
Full Text Available Abstract Background Active efflux systems and reduced cell-wall permeability are considered to be the main causes of mycobacterial intrinsic resistance to many antimicrobials. In this study, we have compared the Mycobacterium smegmatis wild-type strain mc2155 with knockout mutants for porins MspA (the main porin of M. smegmatis and MspC, the efflux pump LfrA (the main efflux pump system of M. smegmatis and its repressor LfrR for their ability to transport ethidium bromide (EtBr on a real-time basis. This information was then correlated with minimum inhibitory concentrations (MICs of several antibiotics in the presence or absence of the efflux inhibitors chlorpromazine, thioridazine and verapamil. Results In the absence of porins MspA and MspC, accumulation of ethidium bromide decreased and the cells became more resistant to several antibiotics, whereas the knockout mutant for the LfrA pump showed increased accumulation of EtBr and increased susceptibility to EtBr, rifampicin, ethambutol and ciprofloxacin. Moreover, the efflux inhibitors caused a reduction of the MICs of streptomycin, rifampicin, amikacin, ciprofloxacin, clarithromycin and erythromycin in most of the strains tested. Conclusions The methodology used in this study demonstrated that porin MspA plays an important role in the influx of quaternary ammonium compounds and antibiotics and that efflux via the LfrA pump is involved in low-level resistance to several antimicrobial drugs in M. smegmatis. The results obtained with this non-pathogenic mycobacterium will be used in future studies as a model for the evaluation of the activity of the same efflux inhibitors on the susceptibility of multidrug resistant strains of Mycobacterium tuberculosis to isoniazid and rifampicin.
8. The aqueous catanionic system sodium perfluorooctanoate-dodecyltrimethylammonium bromide at low concentration.
Science.gov (United States)
López-Fontán, José Luis; Blanco, Elena; Ruso, Juan M; Prieto, Gerardo; Schulz, Pablo C; Sarmiento, Félix
2007-08-15
The interaction between sodium perfluorooctanoate (SPFO) and dodecyltrimethylammonium bromide (DTAB) was studied by several methods and it was found strongly synergistic. Above a mole fraction of SPFO in the surfactant mixture (alpha(SPFO))=0.38, the interaction is repulsive and increases with the content of SPFO in both, the overall mixture and micelles, whereas the interaction is attractive if DTAB is in excess. At alpha(SPFO)=0.38 the low miscibility between hydrocarbon and fluorocarbon is counterbalanced by the electrostatic attraction between the opposite charged head groups, and the micelle composition is ideal (i.e., the mole fraction of SPFO in micelles X(SPFO)=alpha(SPFO)=0.38). The solubility of fluorocarbon in hydrocarbon is lower than that of hydrocarbon in fluorocarbon. Micelles of DTAB act as a solvent for SPFO without important structural changes, whilst micelles of SPFO undergo important changes when dissolve DTAB. This asymmetry may be interpreted as caused by the difference in chain length that favors the inclusion of the shorter chain in micelles of the longer surfactant, but disfavors the opposite process. Above X(SPFO)=0.5 there is an excess adsorption of bromide ions on the mixed micelles surface, giving rise to a high zeta potential. Micelles of pure SPFO or pure DTAB show an important energy barrier which prevents micelle flocculation. The inclusion of SPFO in DTAB micelles produces a reduction of the energy barrier, which disappeared when alpha(SPFO)=0.5. This produces the flocculation of micelles giving rise to the formation of a non-birefringent coacervate, which is probably formed by unordered isometric clusters of micelles.
9. C-N Coupling of nitrogen nucleophiles with aryl and heteroaryl bromides using aminoarenethiolato-copper(I) (pre-)catalyst
NARCIS (Netherlands)
Sperotto, Elena; Klink, Gerard P.M. van; Vries, Johannes G. de; Koten, Gerard van
2010-01-01
The activity of a library of 2-aminoarenethiolato-copper(I) (CuSAr) (pre-)catalyst was explored in the arylation reaction of amines and N-containing heterocycles with aryl and heteroaryl bromides, respectively. These CuSAr pre-catalysts are thermally stable, are soluble in common organic solvents an
10. Protective antiviral immune responses to pseudorabies virus induced by DNA vaccination using dimethyldioctadecylammonium bromide as an adjuvant
NARCIS (Netherlands)
Rooij, van E.M.A.; Glansbeek, H.L.; Hilgers, L.A.T.; Lintelo, te E.G.; Visser, de Y.E.; Boersma, W.J.A.; Haagmans, B.L.; Bianchi, A.T.J.
2002-01-01
To enhance the efficacy of a DNA vaccine against pseudorabies virus (PRV), we evaluated the adjuvant properties of plasmids coding for gamma interferon or interleukin-12, of CpG immunostimulatory motifs, and of the conventional adjuvants dimethyldioctadecylammonium bromide in water (DDA) and sulfoli
11. Suzuki coupling reactions catalyzed by poly(N-ethyl-4-vinylpyridinium bromide stabilized palladium nanoparticles in aqueous solution
Directory of Open Access Journals (Sweden)
2008-04-01
Full Text Available InIn this work, it was investigated to use of poly(N-ethyl-4-vinylpyridinium bromide stabilized palladium nanoparticles in the Suzuki reaction between phenylboronic acid and aryl halides in aqueous solution. The nanoparticles were isolated and re-used several times with low loss of activity.
12. FLUORESCENCE SPECTROSCOPIC STUDY OF THE FORMATION OF HYDROPHOBIC MICRODOMAINS IN AQUEOUS-SOLUTIONS OF POLY(ALKYLMETHYLDIALLYLAMMONIUM BROMIDES)
NARCIS (Netherlands)
YANG, YJ; ENGBERTS, JBFN
1991-01-01
The conformational state of poly(alkylmethyldiallylammonium bromides) was studied in aqueous solutions using pyrene as a fluorescence probe. The results are indicative for the formation of hydrophobic microdomains in the case of several copolymers which possess sufficiently hydrophobic alkyl side ch
13. Grafting, metham sodium, soil solarization and virtually impermeable films as alternative technologies to methyl bromide for Chinese protected tomatoes
Institute of Scientific and Technical Information of China (English)
Han Xuemei; Cao Zhiping; Chen Yunfeng; Chen Guokang; Andrea Camponogara; Yang Hang; Maria Lodovica Gullino
2009-01-01
In the frame of the Sino-ltalian Cooperation Program for Environmental Protection,jointly launched in the year 2000 by the Italian Ministry for Environment and Territory and Sea (IMETS) and the China State Environ nental Protection Administration (SEPA),experimental trials were carried out in Qingzhou city (Shandong Prov ince,China) during 2001-2003 to test several methyl bromide alternative methods to control soilborne diseases in greenhouse tomatoes.Grafting tomatoes on resistant rootstock (Lycopersicon lycopersicum×L.hirsutum),metham sodium applied under traditional polyethylene ptastic films,metham sodium applied at low rate under virtually im permeable films and soil solarization combined with biocontrol agents were the alternatives tested and compared to methyl bromide applied under virtually impermeable plastic films too.Collected data show that resistant rootstock (Lycopersicon lycopersicum × L.hirsutum) introduced from Italy is a promising alternative to methyl bromide for to cal tomato cultivars.Metham sodium applied under traditional polyethylene plastic films is an effective alternative Moreover,virtually impermeable.films demonstrate the help to reduce methyl bromide and metham sodium rates.Finally,soil solarization combined with biocontrol agents does not provide satisfactory resuhs in terms of disease control.
14. High—Speed Analyzing PCR Products of M.tuberculosis Genome Stained by Ethidium Bromide on Microchip Gel Electrophoresis
Institute of Scientific and Technical Information of China (English)
金庆辉; 陈继锋; 等
2002-01-01
The technique of microchip gel electrophoresis(MCGE) was used to analyze the polymerase chain reaction (PCR) products of M.tuberculosis Genome stained by ethidium bromide,The electrophoretic Process was completed within 3-4 min and the results show that the technique of microchip electrophoresis is a high-speed and high-sensitivity analyzing method.
15. Impact of Long-Term Tiotropium Bromide Therapy on Annual Lung Function Decline in Adult Patients with Cystic Fibrosis.
Directory of Open Access Journals (Sweden)
Claudia Brandt
Full Text Available Chronic lung disease is the leading cause of death in patients with Cystic Fibrosis (CF and is often treated with bronchodilators. It is not known whether long-term tiotropium bromide treatment may have a positive impact on lung function.This retrospective cohort study estimated annual lung function decline utilizing longitudinal data for forced expiratory volume in 1 s (FEV1.A total of 160 adult patients with CF were analyzed. The subjects treated for 24 months with tiotropium bromide had a significantly slower decline of mean annual change of FEV1 (treated: -0.3±4.0%; control: -2.3±5.0%; p = 0.0130. In patients with FEV1 ≥70% predicted, long-term tiotropium bromide treatment was associated with greater improvements in annual lung function decline (FEV1 ≥70% predicted: treated: +0.5±4.7%; control: -4.0±6.3%; p = 0.0132; FEV1 50-69% predicted: treated: -0.5±4.4%; control: -0.8±3.8%; p = 0.7142; FEV1 ≤49% predicted: treated: -0.6±3.4%; control: -2.4±4.8%; p = 0.0898.This study suggests that long-term tiotropium bromide treatment may be associated with reduced annual decline of FEV1 in patients with CF, particularly in adults with a mild degree of severity.
16. Formation of halogenated organic byproducts during medium-pressure UV and chlorine coexposure of model compounds, NOM and bromide.
Science.gov (United States)
Zhao, Quan; Shang, Chii; Zhang, Xiangru; Ding, Guoyu; Yang, Xin
2011-12-01
When chlorine is applied before or during UV disinfection of bromide-containing water, interactions between chlorine, bromide and UV light are inevitable. Formation of halogenated organic byproducts was studied during medium-pressure UV (MPUV) and chlorine coexposure of phenol, nitrobenzene and benzoic acid and maleic acid, chosen to represent electron-donating aromatics, electron-withdrawing aromatics, and aliphatic structures in natural organic matter (NOM), respectively. All were evaluated in the presence and absence of bromide. MPUV and chlorine coexposure of phenol produced less total organic halogen (TOX, a collective parameter for halogenated organic byproducts) than chlorination in the dark, and more haloacetic acids instead of halophenols. Increases in TOX were found in the coexposure of nitrobenzene and benzoic acid, but maleic acid was rather inert during coexposure. The presence of bromide increased the formation of brominated TOX but did not significantly affect total TOX formation, in spite of the fact that it reduced hydroxyl radical levels. MPUV and chlorine coexposure of NOM gave a higher differential UV absorbance of NOM and a larger shift to lower molecular weight compounds than chlorination in the dark. However, TOX formation with NOM remained similar to that observed from dark chlorination.
17. Human bones obtained from routine joint replacement surgery as a tool for studies of plutonium, americium and {sup 90}Sr body-burden in general public
Energy Technology Data Exchange (ETDEWEB)
Mietelski, Jerzy W., E-mail: jerzy.mietelski@ifj.edu.pl [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Cracow (Poland); Golec, Edward B. [Traumatology and Orthopaedic Clinic, 5th Military Clinical Hospital and Polyclinic, Independent Public Healthcare Facility, Wroclawska 1-3, 30-901 Cracow (Poland); Orthopaedic Rehabilitation Department, Chair of Clinical Rehabilitation, Faculty of Motor of the Bronislaw Czech' s Academy of Physical Education, Cracow (Poland); Department of Physical Therapy Basics, Faculty of Physical Therapy, Administration College, Bielsko-Biala (Poland); Tomankiewicz, Ewa [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Cracow (Poland); Golec, Joanna [Orthopaedic Rehabilitation Department, Chair of Clinical Rehabilitation, Faculty of Motor of the Bronislaw Czech' s Academy of Physical Education, Cracow (Poland); Physical Therapy Department, Institute of Physical Therapy, Faculty of Heath Science, Jagiellonian University, Medical College, Cracow (Poland); Nowak, Sebastian [Traumatology and Orthopaedic Clinic, 5th Military Clinical Hospital and Polyclinic, Independent Public Healthcare Facility, Wroclawska 1-3, 30-901 Cracow (Poland); Orthopaedic Rehabilitation Department, Chair of Clinical Rehabilitation, Faculty of Motor of the Bronislaw Czech' s Academy of Physical Education, Cracow (Poland); Szczygiel, Elzbieta [Physical Therapy Department, Institute of Physical Therapy, Faculty of Heath Science, Jagiellonian University, Medical College, Cracow (Poland); Brudecki, Kamil [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Cracow (Poland)
2011-06-15
The paper presents a new sampling method for studying in-body radioactive contamination by bone-seeking radionuclides such as {sup 90}Sr, {sup 239+240}Pu, {sup 238}Pu, {sup 241}Am and selected gamma-emitters, in human bones. The presented results were obtained for samples retrieved from routine surgeries, namely knee or hip joints replacements with implants, performed on individuals from Southern Poland. This allowed to collect representative sets of general public samples. The applied analytical radiochemical procedure for bone matrix is described in details. Due to low concentrations of {sup 238}Pu the ratio of Pu isotopes which might be used for Pu source identification is obtained only as upper limits other then global fallout (for example Chernobyl) origin of Pu. Calculated concentrations of radioisotopes are comparable to the existing data from post-mortem studies on human bones retrieved from autopsy or exhumations. Human bones removed during knee or hip joint surgery provide a simple and ethical way for obtaining samples for plutonium, americium and {sup 90}Sr in-body contamination studies in general public. - Highlights: > Surgery for joint replacement as novel sampling method for studying in-body radioactive contamination. > Proposed way of sampling is not causing ethic doubts. > It is a convenient way of collecting human bone samples from global population. > The applied analytical radiochemical procedure for bone matrix is described in details. > The opposite patient age correlations trends were found for 90Sr (negative) and Pu, Am (positive).
18. The recycling of the actinides neptunium, americium and curium in a fast power reactor to reduce the long term activity in a final store
International Nuclear Information System (INIS)
The starting point for the considerations and calculations given in this dissertation is the inevitable production of radioactive materials in the use of nuclear energy, which creates a considerable potential danger in a final store for a very long period. As one possibility of alleviating this problem, a concept for recycling the waste actinides neptunium, americium and curium was proposed. The waste actinides are separated in the reprocessing of burnt-up fuel elements and reach a further irradiation circuit. There they pass through the stages 'manufacture of irradiation elements', 'use in a fast power reactor' and reprocessing of irradiation elements' several times. In each irradiation and subsequent storage, about 17% of the waste actinides are removed by fission or by conversion into nuclides which can be reused as fuel, so that during the life of 40 years of the fast recycling reacor, the waste actinides can be reduced in mass by one half. In order to determine this mass reduction effect, a model calculation was developed, which includes the representation of the neutron physics and thermal properties of the reactor core and the storage and reprocessing of the irradiation elements. (orig./RB)
19. Human bones obtained from routine joint replacement surgery as a tool for studies of plutonium, americium and 90Sr body-burden in general public
International Nuclear Information System (INIS)
The paper presents a new sampling method for studying in-body radioactive contamination by bone-seeking radionuclides such as 90Sr, 239+240Pu, 238Pu, 241Am and selected gamma-emitters, in human bones. The presented results were obtained for samples retrieved from routine surgeries, namely knee or hip joints replacements with implants, performed on individuals from Southern Poland. This allowed to collect representative sets of general public samples. The applied analytical radiochemical procedure for bone matrix is described in details. Due to low concentrations of 238Pu the ratio of Pu isotopes which might be used for Pu source identification is obtained only as upper limits other then global fallout (for example Chernobyl) origin of Pu. Calculated concentrations of radioisotopes are comparable to the existing data from post-mortem studies on human bones retrieved from autopsy or exhumations. Human bones removed during knee or hip joint surgery provide a simple and ethical way for obtaining samples for plutonium, americium and 90Sr in-body contamination studies in general public. - Highlights: → Surgery for joint replacement as novel sampling method for studying in-body radioactive contamination. → Proposed way of sampling is not causing ethic doubts. → It is a convenient way of collecting human bone samples from global population. → The applied analytical radiochemical procedure for bone matrix is described in details. → The opposite patient age correlations trends were found for 90Sr (negative) and Pu, Am (positive).
20. The estimation of reactions of hematopoietic systems of organisms to the effect, caused by americium and plutonium, of nuclear industry workers
Energy Technology Data Exchange (ETDEWEB)
Gasteva, G. N.; Ivanova, T. A.; Gordeeva, A. A.; Suvorova, L. A.; Molokanov, A. A.; Badine, I.
2004-07-01
Object of research are the workers having in an organism radioactive substance (Am-241 and Pu-239). The purpose of work was the estimation of reaction hemopoietic systems of an organism on influence of americium and plutonium at workers of the nuclear industry. At the surveyed contingent of persons the determined effects caused by total influence Am-241 and Pu-239 are ascertained; chronic radiation disease with development, besides diffusive a pneumoscleoris and a chronic toxic-chemical radiating bronchitis, reactions of system of blood, jet hepatopathy which frequency accrued with increase doses loadings and essentially did not depend on age. In peripheral blood on the foreground jet changes act: hyperglobulia, the tendency to neutrophilus leukocytosis, monocytosis, increase ESR, decrease (reduction ?/G of factor reflecting weight and processing of defeat bronchus and pulmonary of system. Stable downstroke in number thrombocytes and reticulocytes in peripheral blood, their direct dependence on a doze of an irradiation, reflect hypoplastic a background hemogenesis, caused by long influence incorporatedin a bone and a bone brain of radioactive substances. At cytologic research punctate a bone brain jet changes which are expressed in increase of functional activity erythro-and myelopoiesiscome to light and provide compensatory reaction of peripheral blood. At histologic research of a bone brain and a bone fabric attributes of development atrophic process which is expressed in reduction of volume parenchyma a bone brain (a fatty atrophy) and dysplasia to a bone fabric are observed.
1. Impact of bromide on halogen incorporation into organic moieties in chlorinated drinking water treatment and distribution systems.
Science.gov (United States)
Tan, J; Allard, S; Gruchlik, Y; McDonald, S; Joll, C A; Heitz, A
2016-01-15
The impact of elevated bromide concentrations (399 to 750 μg/L) on the formation of halogenated disinfection by-products (DBPs), namely trihalomethanes, haloacetic acids, haloacetonitriles, and adsorbable organic halogen (AOX), in two drinking water systems was investigated. Bromine was the main halogen incorporated into all of the DBP classes and into organic carbon, even though chlorine was present in large excess to maintain a disinfectant residual. Due to the higher reactivity of bromine compared to chlorine, brominated DBPs were rapidly formed, followed by a slower increase in chlorinated DBPs. Higher bromine substitution and incorporation factors for individual DBP classes were observed for the chlorinated water from the groundwater source (lower concentration of dissolved organic carbon (DOC)), which contained a higher concentration of bromide, than for the surface water source (higher DOC). The molar distribution of adsorbable organic bromine to chlorine (AOBr/AOCl) for AOX in the groundwater distribution system was 1.5:1 and almost 1:1 for the surface water system. The measured (regulated) DBPs only accounted for 16 to 33% of the total organic halogen, demonstrating that AOX measurements are essential to provide a full understanding of the formation of halogenated DBPs in drinking waters. In addition, the study demonstrated that a significant proportion (up to 94%) of the bromide in source waters can be converted AOBr. An evaluation of AOBr and AOCl through a second groundwater treatment plant that uses conventional treatment processes for DOC removal produced 70% of AOX as AOBr, with 69% of the initial source water bromide converted to AOBr. Exposure to organobromine compounds is suspected to result in greater adverse health consequences than their chlorinated analogues. Therefore, this study highlights the need for improved methods to selectively reduce the bromide content in source waters.
2. Transport of Alachlor, Atrazine, Dicamba, and Bromide through Silt and Loam Soils
Science.gov (United States)
Tindall, J. A.
2015-12-01
The herbicides alachlor, atrazine, and dicamba, as well as bromide were applied to soils overlying the High Plains aquifer in Nebraska, to both macropore and non-macropore sites. Three of 6 study areas (exhibiting a high percentage of macropores) were used for analysis of chemical transport. Twelve intact soil cores (30 cm diameter; 40 cm height), were excavated (two each from 0-40 cm and 40-80 cm depths). The first three study areas and soil cores were used to study preferential flow characteristics using dye staining and to determine hydraulic properties; the remaining cores were treated the same as field macropore sites. Two undisturbed experimental field plots, each with a 1 m2 surface area, were established in each of the three macropore study areas. Each preferential plot was instrumented with suction lysimeters, tensiometers, and neutron access tubes - 10 cm increments to 80 cm - and planted in corn. Three study areas that did not exhibit macropores had alachlor, atrazine, and dicamba and bromide disked into the top 15 cm of soil; concentrations were tracked for 120 days - samples were collected on a grid, distributed within 3 plots measuring 50 m x 50 m each. Core samples were collected prior to and immediately after application, and then at 30, 60, and 120 days after application. Each lab core sample was in 15-cm lengths from 0-15 cm, 15-30 cm, 45-60 cm, and 75-90 cm. For areas exhibiting macropores, herbicides had begun to move between 10-15 days after application with concentrations peaking at various depths after heavy rainfall events. Field lysimeter samples showed increases in concentrations of herbicides at depths where laboratory data indicated greater percentages of preferential flowpaths. Concentrations of atrazine, alachlor and dicamba exceeding 0.30, 0.30, and 0.05 μg m1-1 respectively were observed with depth (10-30 cm and 50-70 cm) after two months following heavy rainfall events indicating that preferential flowpaths were a significant
3. HYOSCINE BUTYL BROMIDE VERSUS DROTAVERINE HYDROCHLORIDE IN ACTIVE STAGE OF LABOUR-A COMPARATIVE STUDY OF RATE OF CERVICAL DILATATION
Directory of Open Access Journals (Sweden)
Misha Pepsi
2014-05-01
Full Text Available AIM: This study was conducted to compare the rate of cervical dilatation with hyoscine butyl bromide and drotaverine hydrochloride in active stage of labour. MATERIALS AND METHODOLOGY: This prospective study was conducted in the department of Obstetrics and Gynaecology. Inclusion Criteria: 1. All women with initial cervical dilatation of 3 cms. 2. When there is a slow rate of cervical dilatation of less than 1.5 cms per hour or decent of less than 1 cm per hour for nulliparous and if dilatation was less than 2cms per hour for a multigravida. 3. And all singleton and cephalic pregnancies were included in this study. Exclusion Criteria included complications like Antepartum haemorrhage, Breech, C.P.D. In this study 400 women were allocated into two groups to receive either Hyoscine butyl bromide or Drotaverine hydrochloride. Two hours after admission in the active stage of labour, progress of labour was reassessed. If the progress of labour was satisfactory, then the wait and watch policy was adopted. If there was no progress they were administered one of the two drugs. 200 patients were administered 10mg of hyoscine butyl bromide suppositories rectally, (GROUP-1 AND THE OTHER 200 WITH 40mg of drotaverine hydrochloride intravenously (GROUP-2. The progress of labour was monitored by the partogram. Not more than 3 doses of hyoscine butyl bromide were administered. RESULTS: The rate of cervical dilatation was 2 cms per hour in group 1 (Hyoscine butyl bromide as compared to 1cm per hour in group 2 (Drotaverine hydrochloride. The difference in rate of cervical dilatation in both the groups was statistically significant. CONCLUSION: There was significant improvement in the rate of cervical dilatation with Hyoscine butyl bromide group of patients. There was a significant reduction in the duration of active stage of labour, and there was no significant second and third stage complication when these drugs were used. No untoward side effects were noted when
4. The construction of TRIGA-TRAP and direct high-precision Penning trap mass measurements on rare-earth elements and americium
Energy Technology Data Exchange (ETDEWEB)
Ketelaer, Jens
2010-06-14
The construction of TRIGA-TRAP and direct high-precision Penning trap mass measurements on rare-earth elements and americium: Nuclear masses are an important quantity to study nuclear structure since they reflect the sum of all nucleonic interactions. Many experimental possibilities exist to precisely measure masses, out of which the Penning trap is the tool to reach the highest precision. Moreover, absolute mass measurements can be performed using carbon, the atomic-mass standard, as a reference. The new double-Penning trap mass spectrometer TRIGA-TRAP has been installed and commissioned within this thesis work, which is the very first experimental setup of this kind located at a nuclear reactor. New technical developments have been carried out such as a reliable non-resonant laser ablation ion source for the production of carbon cluster ions and are still continued, like a non-destructive ion detection technique for single-ion measurements. Neutron-rich fission products will be available by the reactor that are important for nuclear astrophysics, especially the r-process. Prior to the on-line coupling to the reactor, TRIGA-TRAP already performed off-line mass measurements on stable and long-lived isotopes and will continue this program. The main focus within this thesis was on certain rare-earth nuclides in the well-established region of deformation around N {proportional_to} 90. Another field of interest are mass measurements on actinoids to test mass models and to provide direct links to the mass standard. Within this thesis, the mass of {sup 241}Am could be measured directly for the first time. (orig.)
5. Bromate ion formation in dark chlorination and ultraviolet/chlorination processes for bromide-containing water
Institute of Scientific and Technical Information of China (English)
2008-01-01
Bormate (BrO3-) is a carcinogenic chemical produced in ozonation or chlorination of bromide-containing water. Although its formation in seawater with or without sunlight has been previously investigated, the formation of bromate in dilute solutions,particularly raw water for water treatment plant, is unknown. In this article, the results of bench scale tests to measure the formation rates of bromate formation in dilute solutions, including de-ionized water and raw water from Yangtze River, were presented in dark chlorination and ultraviolet (UV)/chlorination processes. And the effects of initial pH, initial concentration of NaOCl, and UV light intensity on bromate formation in UV/chlorination of the diluted solutions were investigated. Detectable bromate was formed in dark chlorination of the two water samples with a relatively slow production rate. Under routine disinfecting conditions, the amount of formed bromate is not likely to exceed the national standards (10 μg/L). UV irradiation enhanced the decay of free chlorine, and,simultaneously, 6.6%-32% of Br- was oxidized to BrO3-. And the formation of bromate exhibited three stages: rapid stage, slow stage and plateau. Under the experimental conditions (pH = 4.41-11.07, CCl2= 1.23-4.50 mg/L), low pH and high chlorine concentration favored the generation of bromate. High light intensity promoted the production rate of bromate, but decreased its total generation amount due to acceleration of chlorine decomposition.
6. Ozone Therapy in Ethidium Bromide-Induced Demyelination in Rats: Possible Protective Effect.
Science.gov (United States)
Salem, Neveen A; Assaf, Naglaa; Ismail, Manal F; Khadrawy, Yasser A; Samy, Mohga
2016-08-01
Multiple sclerosis, an autoimmune inflammatory disease of the central nervous system, is characterized by excessive demyelination. The study aimed to investigate the possible protective effect of ozone (O3) therapy in ethidium bromide (EB)-induced demyelination in rats either alone or in combination with corticosteroids in order to decrease the dose of steroid therapy. Rats were divided into Group (1) normal control rats received saline, Group (2) Sham-operated rats received saline, Group (3) Sham-operated rats received vehicle (oxygen), Group (4) EB-treated rats received EB, Group (5) EB-treated rats received O3, Group (6) EB-treated rats received methylprednisolone (MP), and Group (7) EB-treated rats received half the dose of MP concomitant with O3. EB-treated rats showed a significant increase in the number of footfalls in the grid walk test, decreased brain GSH, and paraoxonase-1 enzyme activity, whereas brain MDA, TNF-α, IL-1β, INF-γ, Cox-2 immunoreactivity, and p53 protein levels were increased. A significant decline in brain serotonin, dopamine, norepinephrine, and MBP immunoreactivity was also reported. Significant improvement of the above-mentioned parameters was demonstrated with the administration of either MP or O3, whereas best amelioration was achieved by combining half the dose of MP with ozone. PMID:26467344
7. Photocontrol of Voltage-Gated Ion Channel Activity by Azobenzene Trimethylammonium Bromide in Neonatal Rat Cardiomyocytes.
Directory of Open Access Journals (Sweden)
Sheyda R Frolova
Full Text Available The ability of azobenzene trimethylammonium bromide (azoTAB to sensitize cardiac tissue excitability to light was recently reported. The dark, thermally relaxed trans- isomer of azoTAB suppressed spontaneous activity and excitation propagation speed, whereas the cis- isomer had no detectable effect on the electrical properties of cardiomyocyte monolayers. As the membrane potential of cardiac cells is mainly controlled by activity of voltage-gated ion channels, this study examined whether the sensitization effect of azoTAB was exerted primarily via the modulation of voltage-gated ion channel activity. The effects of trans- and cis- isomers of azoTAB on voltage-dependent sodium (INav, calcium (ICav, and potassium (IKv currents in isolated neonatal rat cardiomyocytes were investigated using the whole-cell patch-clamp technique. The experiments showed that azoTAB modulated ion currents, causing suppression of sodium (Na+ and calcium (Ca2+ currents and potentiation of net potassium (K+ currents. This finding confirms that azoTAB-effect on cardiac tissue excitability do indeed result from modulation of voltage-gated ion channels responsible for action potential.
8. Pourbaix diagrams for titanium in concentrated aqueous lithium bromide solutions at 25 oC
International Nuclear Information System (INIS)
Research highlights: → The titanium solubility range increases slightly with increasing Br- activity. → The passivation area decreases slightly with increasing Br- activity. → Immunity area increases slightly with increasing Br- activity. → The titanium immunity disappears in the presence of titanium hydrides. → TiH2 is the stable species at low potentials in the presence of titanium hydrides. - Abstract: Pourbaix diagrams (electrode potential-pH diagrams) for Ti-Br--H2O system at 25 oC in the absence and presence of titanium hydrides were developed in 400, 700, 850, and 992 g/L LiBr solutions. The diagrams were compared with the simple Ti-H2O system at 25 oC. Comparison of the simple Ti-H2O system with the diagrams of the Ti-Br--H2O system at 25 oC showed that the titanium solubility range in the acid, neutral, and weak alkaline areas of the diagrams extended slightly to both higher pH values and potentials with increasing bromide ion activity and decreasing water activity.
9. Influence of Low Cetyltrimethylammonium Bromide Concentration on the Interactions and Properties of Hemoglobin with Acyclovir
Institute of Scientific and Technical Information of China (English)
LIU Tian-Qing; GUO Rong
2006-01-01
The effects of cetyltrimethylammonium bromide (CTAB) on the properties of hemoglobin (Hb) at low CTAB concentration were studied in Hb/acyclovir/CTAB system by the methods of UV-Vis spectrum, fluorescence, zeta potential, conductivity and negative-staining transmission electron microscope (TEM). With the increase of CTAB concentration, the UV peak intensity at 276 nm, the intrinsic fluorescence, the zeta potential of Hb and the system conductivity were all enhanced. Hb was easily oxidized to oxyHb and hemichrome. In Hb/acyclovir/CTAB system,CTAB made the UV-Vis spectrum, fluorescence, conductivity and conformation of Hb tend to be returned to those of the original Hb but the zeta potential not to do so. The UV absorption peak of Hb-acyclovir complex disappeared,and the tight structure of Hb aroused by acyclovir was refolded. When CTAB concentration was higher than 5 ×10-5 mol/L, the two absorption peaks at 536 and 576 nm appeared again, and the Hb structure became looser again.
10. Room temperature X- and gamma-ray detectors using thallium bromide crystals
CERN Document Server
Hitomi, K; Shoji, T; Suehiro, T; Hiratate, Y
1999-01-01
Thallium bromide (TlBr) is a compound semiconductor with wide band gap (2.68 eV) and high X- and gamma-ray stopping power. The TlBr crystals were grown by the horizontal travelling molten zone (TMZ) method using purified material. Two types of room temperature X- and gamma-ray detectors were fabricated from the TlBr crystals: TlBr detectors with high detection efficiency for positron annihilation gamma-ray (511 keV) detection and TlBr detectors with high-energy resolution for low-energy X-ray detection. The detector of the former type demonstrated energy resolution of 56 keV FWHM (11%) for 511 keV gamma-rays. Energy resolution of 1.81 keV FWHM for 5.9 keV was obtained from the detector of the latter type. In order to analyze noise characteristics of the detector-preamplifier assembly, the equivalent noise charge (ENC) was measured as a function of the amplifier shaping time for the high-resolution detector. This analysis shows that parallel white noise and 1/f noise were dominant noise sources in the detector...
11. Effects of Cholinergic Stimulation with Pyridostigmine Bromide on Chronic Chagasic Cardiomyopathic Mice
Directory of Open Access Journals (Sweden)
Marília Beatriz de Cuba
2014-01-01
Full Text Available The aim of the present study was to assess the effects of an anticholinesterase agent, pyridostigmine bromide (Pyrido, on experimental chronic Chagas heart disease in mice. To this end, male C57BL/6J mice noninfected (control:Con or chronically infected (5 months with Trypanosoma cruzi (chagasic:Chg were treated or not (NT with Pyrido for one month. At the end of this period, electrocardiogram (ECG; cardiac autonomic function; heart histopathology; serum cytokines; and the presence of blood and tissue parasites by means of immunohistochemistry and PCR were assessed. In NT-Chg mice, significant changes in the electrocardiographic, autonomic, and cardiac histopathological profiles were observed confirming a chronic inflammatory response. Treatment with Pyrido in Chagasic mice caused a significant reduction of myocardial inflammatory infiltration, fibrosis, and hypertrophy, which was accompanied by a decrease in serum levels of IFNγ with no change in IL-10 levels, suggesting a shift of immune response toward an anti-inflammatory profile. Lower nondifferent numbers of parasite DNA copies were observed in both treated and nontreated chagasic mice. In conclusion, our findings confirm the marked neuroimmunomodulatory role played by the parasympathetic autonomic nervous system in the evolution of the inflammatory-immune response to T. cruzi during experimental chronic Chagas heart disease in mice.
12. The DNA intercalators ethidium bromide and propidium iodide also bind to core histones
Directory of Open Access Journals (Sweden)
Amrita Banerjee
2014-01-01
Full Text Available Eukaryotic DNA is compacted in the form of chromatin, in a complex with histones and other non-histone proteins. The intimate association of DNA and histones in chromatin raises the possibility that DNA-interactive small molecules may bind to chromatin-associated proteins such as histones. Employing biophysical and biochemical techniques we have characterized the interaction of a classical intercalator, ethidium bromide (EB and its structural analogue propidium iodide (PI with hierarchical genomic components: long chromatin, chromatosome, core octamer and chromosomal DNA. Our studies show that EB and PI affect both chromatin structure and function, inducing chromatin compaction and disruption of the integrity of the chromatosome. Calorimetric studies and fluorescence measurements of the ligands demonstrated and characterized the association of these ligands with core histones and the intact octamer in absence of DNA. The ligands affect acetylation of histone H3 at lysine 9 and acetylation of histone H4 at lysine 5 and lysine 8 ex vivo. PI alters the post-translational modifications to a greater extent than EB. This is the first report showing the dual binding (chromosomal DNA and core histones property of a classical intercalator, EB, and its longer analogue, PI, in the context of chromatin.
13. Synthesis of zeolitic materials from volcanic ash in presence and absence of cetyltrimethylammonium bromide
International Nuclear Information System (INIS)
Zeolitic materials as Na-phillipsite, Na-K-phillipsite-like zeolites and the mixtures of zeolites (phillipsite+analcime and phillipsite+chabazite+analcime) were synthesized from volcanic ash, either in presence and absence of cetiltrimetilamonium bromide (CTAB). The ash sample used in the laboratory experiments contains 75.36% SiO2 and 14.11% Al2O3, abundances. The reaction time as well as the influence of CTAB were studied in the zeolitic materials crystallization. The experiments were carried out under hydrothermal conditions, autogenic pressure and temperature of 150 grades C, as well as reaction time from 8 to 116 h. Products from this hydrothermal treatment were identified by X-ray diffraction (XRD) and characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (Sem-EDS). Of the zeolitic materials obtained the Na-K-phillipsite-like zeolite was found to be the most effective for the retention of cations Pb2+, Zn2+ and Ba2+. (Author)
14. Shape-directing role of cetyltrimethylammonium bromide on the morphology of extracellular synthesis of silver nanoparticles
Directory of Open Access Journals (Sweden)
Shaeel Ahmed Al-Thabaiti
2015-07-01
Full Text Available Oriental plane leaf extracts were used as a reducing-, stabilizing- and capping-agent for the preparation of silver nanoparticles (AgNPs for the first time. The size, shape, size distribution and optical properties strongly depend on the experimental conditions, absence, and presence of shape-directing cetyltrimethylammonium bromide (CTAB. UV–vis spectroscopy, transmission electron microscopy and selected electron diffraction ring patterns were used to determine the morphology of resulting AgNPs at different time intervals. The spectra showed a surface Plasmon resonance (SPR peak at 450 nm which is the characteristic of spherical AgNPs (diameter ranging from 10 to 30 nm. The peak shifted to shorter wavelength (blue shift from 450 to 425 nm and sharpness of the peak also decreases in the presence of CTAB which might be due to the capping action of CTAB. A layer of ca. 3 nm around a group of the AgNPs in which the inner layer is bound to the AgNPs surface via the active groups of the extract has been observed.
15. Interactions of cellulose-based comb polyelectrolyte with oppositely charged surfactant dodecyl-trimethylammonium bromide.
Science.gov (United States)
Pan, Hong; Chen, Pei-Yao; Liu, Hai-Xue; Chen, Yu; Wei, Yu-Ping; Zhang, Ming-Jie; Cheng, Fa
2012-07-01
A comb ethyl cellulose-g-sodium polyacrylate (EC-g-SPA) was synthesized by atom transfer radical polymerization. The amphiphilic properties of the EC-g-SPA were determined by surface tension measurements. The interactions between EC-g-SPA and the cationic surfactant dodecyl-trimethylammonium bromide (C12TAB) were investigated by surface tension, turbidity, dynamic light scattering and transmission electron microscopy (TEM). The results revealed that the critical aggregate concentration (CAC) of the complexes was 0.8mM. When the C12TAB concentration was lower than the CAC, the hydrodynamic diameter (Dh) of the complexes decreased as the surfactant concentration was increased. As the C12TAB concentration was increased above the CAC, the Dh initially increased slightly, followed by a sharp decrease. The changes in the sizes and shapes of the aggregates were studied by TEM. The interactions between two species and the structure of the EC-g-SPA/C12TAB complexes were also discussed. PMID:24750878
16. Computational study of dissociative electron attachment to π-allyl ruthenium (II) tricarbonyl bromide
Science.gov (United States)
Thorman, Rachel M.; Bjornsson, Ragnar; Ingólfsson, Oddur
2016-08-01
Motivated by the current interest in low energy electron induced fragmentation of organometallic complexes in focused electron beam induced deposition (FEBID) we have evaluated different theoretical protocols for the calculation of thermochemical threshold energies for DEA to the organometallic complex π-allyl ruthenium (II) tricarbonyl bromide. Several different computational methods including density functional theory (DFT), hybrid-DFT and coupled cluster were evaluated for their ability to predict these threshold energies and compared with the respective experimental values. Density functional theory and hybrid DFT methods were surprisingly found to have poor reliability in the modelling of several DEA reactions; however, the coupled cluster method LPNO-pCCSD/2a was found to produce much more accurate results. Using the local correlation pair natural orbital (LPNO) methodology, high level coupled cluster calculations for open-shell systems of this size are now affordable, paving the way for reliable theoretical DEA predictions of such compounds. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.
17. Water-lithium bromide double-effect absorption cooling analysis. Final report
Energy Technology Data Exchange (ETDEWEB)
Vliet, G.C.; Lawson, M.B.; Lithgow, R.A.
1980-12-01
This investigation involved the development of a numerical model for the transient simulation of the double-effect, water-lithium bromide absorption cooling machine, and the use of the model to determine the effect of the various design and input variables on the absorption unit performance. The performance parameters considered were coefficient of performance and cooling capacity. The sensitivity analysis was performed by selecting a nominal condition and determining performance sensitivity for each variable with others held constant. The variables considered in the study include source hot water, cooling water, and chilled water temperatures; source hot water, cooling water, and chilled water flow rates; solution circulation rate; heat exchanger areas; pressure drop between evaporator and absorber; solution pump characteristics; and refrigerant flow control methods. The performance sensitivity study indicated in particular that the distribution of heat exchanger area among the various (seven) heat exchange components is a very important design consideration. Moreover, it indicated that the method of flow control of the first effect refrigerant vapor through the second effect is a critical design feature when absorption units operate over a significant range of cooling capacity. The model was used to predict the performance of the Trane absorption unit with fairly good accuracy. The dynamic model should be valuable as a design tool for developing new absorption machines or modifying current machines to make them optimal based on current and future energy costs.
18. Denaturation and intermediates study of two sturgeon hemoglobins by n-dodecyl trimethylammonium bromide
Science.gov (United States)
Ariaeenejad, Shohreh; Habibi-Rezaei, Mehran; Kavousi, Kaveh; Jamili, Shahla; Fatemi, Mohammad Reza; Hong, Jun; Poursasan, Najmeh; Sheibani, Nader; Moosavi-Movahedi, Ali. A.
2013-01-01
Varieties of hemoglobin (Hb) forms exist in fish, which are usually well adapted to the different ecological conditions or various habitats. In the current study, Hbs from two Sturgeon species of the Southern Caspian Sea Basin were purified and studied upon interaction with n-dodecyl trimethylammonium bromide (DTAB; as a cationic surfactant) by various methods including UV-visible absorption, dynamic light scattering (DLS), and ANS fluorescence spectrophotometry. The chemometric analysis of Hbs was investigated upon interaction with DTAB under titration, using UV-visible absorption spectra. The chemometric resolution techniques were used to determine the number of the components and mole fraction of the oxidized Hbs. These results provided the evidence for the existence of three different molecular components including native (N), intermediate (I) and denatured (D) in sturgeon Hbs. According to the distribution of intermediates, which were broadened in a range of DTAB concentration, the aggregation states, DLS experiments, and thermal stability (Tm obtained by differential scanning calorimetry (DSC)), the Acipenser stellatus Hb was more stable compared to Acipenser persicus Hb. These results demonstrate a significant relationship between the stability of fish Hbs and the habitat depth requirements. PMID:23142155
19. The sorption behavior of DDT onto sediment in the presence of surfactant cetyltrimethylammonium bromide
International Nuclear Information System (INIS)
Highlights: → The sorption behavior of a complex system consists of DDT and CTAB onto marine sediment was studied. → Batch experiments were carried out to investigate the kinetics and thermodynamics. → The presence of CTAB could remarkably accelerate and enhance the sorption of DDT. → The sorption of DDT had relatively more negative ΔG0 and ΔH0 in the presence of CTAB. - Abstract: The sorption behavior of p,p'- and o,p'-dichlorodiphenyltrichloroethane (DDT) in the presence of a cationic surfactant cetyltrimethylammonium bromide (CTAB) on sediment was studied. Batch experiments were carried out to investigate the kinetics and thermodynamics of the process. The kinetic behavior of these three chemicals on sediment was described by pseudo-second-order kinetic equations, and the isotherms followed the Freundlich model well. The presence of CTAB was able to remarkably accelerate and enhance the sorption of DDT, whereas DDT showed no effect on the sorption of CTAB in our considered concentration ranges. The thermodynamic parameters, such as standard enthalpy change (ΔH0), standard entropy change (ΔS0) and standard Gibbs free energy change (ΔG0) showed that the sorption process of p,p'- and o,p'-DDT was physical, spontaneous and exothermic, and the randomness at the solid-liquid interface increased during the process. In the presence of CTAB, the sorption of DDT showed significantly negative ΔG0 and ΔH0 values.
20. Electrodeposition of Nanocrystalline Chromium Coatings Based on 1-Butyl-3-Methylimidazolium-Bromide Ionic Liquid.
Science.gov (United States)
He, Xinkuai; Zhu, Qingyun; Hou, Bailong; Cai, Youxing; Li, Chen; Fu, Liqin; Wu, Luye
2015-12-01
The electrochemical behavior of trivalent chromium reduction from 1-butyl-3-methylimidazolium-bromide ([BMIM]Br) ionic liquid is studied. The result of cyclic voltammetry shows that the Cr(III) reduction is irreversible and occurs in two steps, Cr(III)to Cr(II), and Cr(II) to Cr(0), respectively. In the electrochemical impedance spectroscopy measurements, the preferable equivalent circuit is made to fit the experimental data. The effects of electroplating parameters on coating thickness and electrodepositon rate are investigated by potentiostatic method on Cu electrode from Cr(III)-[BMIM]Br solution. The results show that the temperature and depositing potential have great effect on the coating thickness and electrodeposition rate. The surface morphology and composition of deposited Cr are investigated using scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). SEM analysis shows that chromium electrodeposits obtained on Cu electrodes present a ball-like structure. EDS analysis shows that the coatings are composed of Cr. Moreover, the corrosion resistance of the as-deposited chromium layer is evaluated using polarization curves. The results show that the corrosion resistance of the chromium coatings obtained at higher potential is better. PMID:26682363
1. Binding of dyes to hydroxyapatite treated with cetylpyridinium chloride or cetrimonium bromide.
Science.gov (United States)
Jensen, J E
1978-03-01
The effect of cetylpyridinium chloride (CPC) and cetrimonium bromide (CTAB) on the adsorption of some acidic food dyes to hydroxyapatite was studied. The dyes investigated were brilliant blue (FD&C Blue No. 1), tartrazine (FD&C Yellow No. 5), sunset yellow (FD&C Yellow No. 6) and amaranth (FD&C Red No. 2). The apatite had adsorbed 9.2 mumol CPC per g dry weight. The adsorbed CPC was in equilibrium with a free concentration of 20 microgram/ml (58 micrometer). The adsorption of CPC and CTAB to the apatite was followed by an increased ability of the crystals to bind the dyes. The dyes were very firmly adsorbed and were not released during a series of washings. Untreated apatite showed only a minor affinity for the dyes. The adsorbed dyes were easily washed out. CPC and CTAB showed the smae specific ability to increase the binding capacity of the apatite. The results are discussed and related to the formation of stains on the teeth in persons using quaternary ammonium compounds for mouthrinsing. A mechanism explaining the production of stains is proposed.
2. Dehalogenative Homocoupling of Terminal Alkynyl Bromides on Au(111): Incorporation of Acetylenic Scaffolding into Surface Nanostructures.
Science.gov (United States)
Sun, Qiang; Cai, Liangliang; Ma, Honghong; Yuan, Chunxue; Xu, Wei
2016-07-26
On-surface C-C coupling reactions of molecular precursors with alkynyl functional groups demonstrate great potential for the controllable fabrication of low-dimensional carbon nanostructures/nanomaterials, such as carbyne, graphyne, and graphdiyne, which demand the incorporation of highly active sp-hybridized carbons. Recently, through a dehydrogenative homocoupling reaction of alkynes, the possibility was presented to fabricate surface nanostructures involving acetylenic linkages, while problems lie in the fact that different byproducts are inevitably formed when triggering the reactions at elevated temperatures. In this work, by delicately designing the molecular precursors with terminal alkynyl bromide, we introduce the dehalogenative homocoupling reactions on the surface. As a result, we successfully achieve the formation of dimer structures, one-dimensional molecular wires and two-dimensional molecular networks with acetylenic scaffoldings on an inert Au(111) surface, where the unexpected C-Au-C organometallic intermediates are also observed. This study further supplements the database of on-surface dehalogenative C-C coupling reactions, and more importantly, it provides us an alternative efficient way for incorporating the acetylenic scaffolding into low-dimensional surface nanostructures. PMID:27326451
3. Spectroscopic study of tetradecyltrimethylammonium bromide Pt-C14TAB nanoparticles: Structure and Stability
Energy Technology Data Exchange (ETDEWEB)
Borodko, Y.; Jones, L.; Frei, H.; Somorjai, G.
2009-01-09
The vibrational spectra of platinum nanoparticles (12 nm) capped with tetradecyltrimethylammonium bromide, C{sub 14}TAB, were investigated by Fourier transform infrared (FTIR) spectroscopy. We have shown that the thermal decay of Pt-C{sub 14}TAB nanoparticles in N{sub 2}, H{sub 2} and O{sub 2} atmospheres leads to the release of hydrocarbon chain of surfactant and the formation of strongly bonded layer of ammonium cations on the platinum surface. The platinum atoms accessible to CO chemisorptions were not reducible by hydrogen in the temperature ranging from 30 C to 200 C. A FTIR spectrum of C{sub 14}TAB adsorbed on Pt nanoparticles dramatically perturbed as compared with pure C{sub 14}TAB. New intense and broad bands centered at 1450 cm{sup -1} and 760 cm{sup -1} are making their appearance in Pt-C{sub 14}TAB. It may be speculated, that new bands are result of coupling between conducting electrons of Pt and molecular vibrations of adsorbed C{sub 14}TAB and as a consequence specific vibrational modes of ammonium cation transformed into electron-vibrational modes.
4. Methyl chloride and methyl bromide emissions from baking: an unrecognized anthropogenic source.
Science.gov (United States)
Thornton, Brett F; Horst, Axel; Carrizo, Daniel; Holmstrand, Henry
2016-05-01
Methyl chloride and methyl bromide (CH3Cl and CH3Br) are the largest natural sources of chlorine and bromine, respectively, to the stratosphere, where they contribute to ozone depletion. We report the anthropogenic production of CH3Cl and CH3Br during breadbaking, and suggest this production is an abiotic process involving the methyl ester functional groups in pectin and lignin structural polymers of plant cells. Wide variations in baking styles allow only rough estimates of this flux of methyl halides on a global basis. A simple model suggests that CH3Br emissions from breadbaking likely peaked circa 1990 at approximately 200tonnes per year (about 0.3% of industrial production), prior to restrictions on the dough conditioner potassium bromate. In contrast, CH3Cl emissions from breadbaking may be of similar magnitude as acknowledged present-day CH3Cl industrial emissions. Because the mechanisms involve functional groups and compounds widely found in plant materials, this type of methyl halide production may occur in other cooking techniques as well. PMID:26878644
5. Swelling behaviour of amphiphilic poly (methacryloxyethl dimethylalkane ammonium bromide) gels in alcohol/water solvent systems
International Nuclear Information System (INIS)
Three kinds of amphiphilic PMADAB gels were prepared through radiation-induced polymerization and crosslinking of methacryloxyethyl dimethylalkane ammonium bromide (MADAB) with different alkyl side chains (butyl, octyl and dodecyl). The length of alkyl side chains had significant influence on swelling behavior of the PMADAB gels in alcohol/water solvent. Equilibrium swelling degree (EDS) of PMBDAB (butyl) gel in water was ca. 160 and decreased with increasing alcohol content (x), whereas EDS of PMODAB (octyl) and PMDDDAB (dodecyl) gels showed a convex-upward function of x, i.e., these two gels barely swelled in pure water and swelled with increasing x and then shrank gradually. This phenomenon was explained by the hydrophobic association of long alkyl chains and a cosolvency effect of PMADAB in alcohol and water. The swelling behavior of PMADAB gels in methanol, ethanol and isopropanol were similar, and their EDS are related with the dielectric constant of alcohol solvents. The results suggest that PMADAB gels may be potential absorbents for various kinds of alcohols. (authors)
6. Application of cetyltrimethylammonium bromide bentonite-titanium dioxide photocatalysis technology for pretreatment of aging leachate.
Science.gov (United States)
Cai, Fei-Fei; Yang, Zhao-Hui; Huang, Jing; Zeng, Guang-Ming; Wang, Li-Ke; Yang, Jian
2014-06-30
Organobentonite-photocatalysis technology was applied to pretreat aging leachate containing refractory pollutants. The organobentonite was synthesized by organic modifier cetyltrimethylammonium bromide (CTMAB) and natural bentonite. In characterization experiments, we could confirm that organic functional groups of cetyltrimethylammonium (CTMA(+)) cations were successfully loaded on the surface of bentonite. The combination of CTMAB2.5 adsorption and TiO2 photocatalysis was superior to either running separately. Furthermore, removal efficiency of simultaneously utilizing CTMAB2.5 and TiO2 was better than them in succession. The combination technology was feasible and was optimized by response surface methodology (RSM) with COD and NH3-N removal rate as the target responses. The optimal operation conditions calculated from the regression equations were CTMAB2.5 dosage of 7.5 g/L, pH at 3.5, TiO2 dosage of 1.63 g/L, and reaction time for 60.02 min, which maintained the removal of COD and NH3-N at 82% and 37%, respectively.
7. Irradiation as an alternative treatment to methyl bromide for insect control
International Nuclear Information System (INIS)
Methyl Bromide (MB) is widely used as a fumigant for the control of pests of stored grain, legumes, oil seeds, dry fruits and nuts, pest of timber, soil insects, soil nematodes, soil pathogens of plants, and as a quarantine treatment against pest of fresh horticultural products, and pests and diseases in propagation material. The global phase-out of MBB in advanced countries by 2005 and in developing countries by 2015 under the Montreal Protocol, because of its ozone depleting property, has prompted increasing interest in the use of irradiation as an alternative to MB for insect control in food and agricultural commodities in recent years. Irradiation at fairly low doses, of the order of 1 kGy or less is an effective alternative to chemical treatment of foods. The advantages of radiation processing include short treatment time in comparison to several days of exposure required in chemical fumigation, no undesirable chemical residues in the food, no resistance developed by the insects and no significant changes in the organoleptic, physicochemical and functional properties or the nutritive value of the treated products. Turkey is the leading country in the world, in production and exports of dried fig, apricot,raisin and hazelnut. One of the main problem in the export trade is infestation by stored product insects. In Turkey, the new legal regulations on food irradiation were published in Official Newspaper on November 6, 1999. (3 tables and 10 refs. included)
8. Interferences in automated phenol red method for determination of bromide in water
Science.gov (United States)
Basel, C.L.; Defreese, J.D.; Whittemore, D.O.
1982-01-01
The phenol red method for the determination of bromide in water has been automated by segmented flow analysis. Samples can be analyzed at a rate of 20 samples/h with a method detection limit, defined, as the concentration giving a signal about three times the standard deviation of replicate anaiyte determinations in reagent water, of 10 ??g/L. Samples studied include oil-field brines, halite solution brines, ground-waters contaminated with these brines, and fresh groundwaters. Chloride and bicarbonate cause significant positive interferences at levels as low as 100 mg/L and 50 mg/L, respectively. Ammonia gives a negative interference that is important at levels as low as 0.05 mg/L. An ionic strength buffer is used to suppress a positive ionic strength interference, correction curves are used to compensate for the chloride interference, the bicarbonate interference is minimized by acidification, and the ammonia interference is eliminated by its removal by ion exchange. Reaction product studies are used to suggest a plausible mode of chloride interference. ?? 1982 American Chemical Society.
9. Carboxymethylcellulose acetate butyrate/poly(4-vinyl-N-pentyl pyridinium bromide blends as antimicrobial coatings
Directory of Open Access Journals (Sweden)
L. S. Blachechen
2015-09-01
Full Text Available Blends of carboxymethyl cellulose acetate butyrate (CMCAB, a cellulose derivative, and poly(4-vinyl-N-pentyl pyridinium bromide (QPVP-C5, an antimicrobial polymer, were prepared by casting method and characterized by means of Fourier transform infrared vibrational spectroscopy (FTIR, scanning electron microscopy (SEM, thermogravimetric analysis (TGA, differential scanning calorimetry (DSC and contact angle measurements. Miscibility between CMCAB and QPVP-C5 was evidenced by DSC measurements of blends, which showed a single thermal event of Tg, and SEM images, which revealed homogenous morphology, regardless the blend composition. Moreover, thermal stability of QPVP-C5 was substantially enhanced, when it was mixed with CMCAB. Upon increasing the QPVP-C5 content in the blend the wettability and antimicrobial activity against Gram-positive bacteria Micrococcus luteus increased, indicating the surface enrichment by pyridinium groups. In fact, blends with 70 wt% QPVP-C5 reduced 5 log and 4 log the colony-forming units of Micrococcus luteus and Escherichia coli, respectively.
10. Self-assembly Of cetyl trimethylammonium bromide in ethanol-water mixtures
Institute of Scientific and Technical Information of China (English)
Li Wei; Zhang Ming; Zhang Jinli; Han Yongcai
2006-01-01
The critical micelle concentration (CMC) of cetyl trimethylammonium bromide (CTAB) in both water and ethanol-water-mixed solvent was determined using steady- state fluorescence techniques in order to investigate the effect of the self-assembling properties of the surfactant on the template synthesis of porous inorganic materials.Results indicated that the CMC increased with the increase of ethanol concentration in the mixed solvent.The CMC of CTAB is 0.0009 mol/L in water,while it is 0.24 mol/L in ethanol.Furthermore,the dissipative particle dynamics (DPD) was adopted to simulate the aggregation of CTAB in water and ethanol/water mixtures,and the energy difference was calculated for the surfactant tail groups after mixing with the solvent.The simulation results reflected a regularity similar to the experimental data,i.e.,tail groups of CTAB interacted more strongly with ethanol than with water,which elucidates the reason that the micelle is difficult to form in ethanol.
11. Dual bronchodilator therapy with aclidinium bromide/formoterol fumarate for chronic obstructive pulmonary disease.
Science.gov (United States)
D'Urzo, Tony; Donohue, James F; Price, David; Miravitlles, Marc; Kerwin, Edward
2015-10-01
Inhaled bronchodilator therapy is a mainstay of treatment for chronic obstructive pulmonary disease (COPD). Despite the number and types of treatments available, the control of symptoms and exacerbations remains suboptimal, and adherence to, and persistence with, inhaled therapy is generally poor. Results from clinical studies suggest that dual bronchodilator therapy with long-acting muscarinic receptor antagonists (LAMAs) and long-acting β2 adrenergic receptor agonists (LABAs) may provide additional benefit over LAMA or LABA monotherapy without additive effects on safety and tolerability. Several combinations of a LAMA plus a LABA have recently become available in a single inhaler for maintenance therapy for adults with moderate-to-severe COPD, including aclidinium bromide/formoterol fumarate, glycopyrronium/indacaterol and umeclidinium/vilanterol. Here, we review clinical data demonstrating significant improvements in bronchodilation, 24-h symptoms, and health status with aclidinium/formoterol twice daily, and discuss how this treatment can be implemented in clinical practice as part of a patient-focused approach to disease control. PMID:26366803
12. Prolonged use of pancuronium bromide and sensorineural hearing loss in childhood survivors of congenital diaphragmatic hernia.
Science.gov (United States)
Cheung, P Y; Tyebkhan, J M; Peliowski, A; Ainsworth, W; Robertson, C M
1999-08-01
Sensorineural hearing loss (SNHL) is a significant neurologic morbidity in survivors of neonatal congenital diaphragmatic hernia (CDH), with a reported incidence of up to 60%. In a historical cohort study of 37 neonates with CDH, we investigated the use of pancuronium bromide (PB) and common ototoxic drugs during the neonatal period and their relationship to SNHL in childhood survivors. Survivors with SNHL (n = 23) had significantly higher cumulative dose of PB administered during the neonatal illness than survivors without SNHL (n = 14). The cumulative dose and duration of PB use significantly correlated (r = 0.66-0.81) and independently predicted (adjusted r (2) = 0.42-0.64) the greatest intensity (in decibels) and the widest band (lowest frequency in hertz) loss of SNHL. No differences were identified between survivors with and without SNHL regarding demographic and neonatal characteristics (including oxygenation and ventilation variables and the cumulative dose and duration of therapy with aminoglycosides, vancomycin, and furosemide), although survivors with SNHL had received a modestly higher cumulative dose of ethacrynic acid than survivors without SNHL. Although we show that prolonged administration of PB during the neonatal period is associated with SNHL in childhood survivors of CDH, further multicenter studies are required to investigate the possible etiologies of SNHL in this high-risk population.
13. Evaluation of methyl bromide alternatives efficacy against soil-borne pathogens, nematodes and soil microbial community.
Directory of Open Access Journals (Sweden)
Hongwei Xie
Full Text Available Methyl bromide (MB and other alternatives were evaluated for suppression of Fusarium spp., Phytophthora spp., and Meloidogyne spp. and their influence on soil microbial communities. Both Fusarium spp. and Phytophthora spp. were significantly reduced by the MB (30.74 mg kg-1, methyl iodide (MI: 45.58 mg kg-1, metham sodium (MS: 53.92 mg kg-1 treatments. MS exhibited comparable effectiveness to MB in controlling Meloidogyne spp. and total nematodes, followed by MI at the tested rate. By contrast, sulfuryl fluoride (SF: 33.04 mg kg-1 and chloroform (CF: 23.68 mg kg-1 showed low efficacy in controlling Fusarium spp., Phytophthora spp., and Meloidogyne spp. MB, MI and MS significantly lowered the abundance of different microbial populations and microbial biomass in soil, whereas SF and CF had limited influence on them compared with the control. Diversity indices in Biolog studies decreased in response to fumigation, but no significant difference was found among treatments in PLFA studies. Principal component and cluster analyses of Biolog and PLFA data sets revealed that MB and MI treatments greatly influenced the soil microbial community functional and structural diversity compared with SF treatment. These results suggest that fumigants with high effectiveness in suppressing soil-borne disease could significantly influence soil microbial community.
14. Corrosion rate of copper in aqueous lithium bromide concentrated solutions at room temperature by immersion tests
Energy Technology Data Exchange (ETDEWEB)
Munoz-Portero, M.J.; Garcia-Anton, J.; Guinon-Segura, J.L.; Perez-Herranz, V. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain)
2004-07-01
Concentrated solutions of lithium bromide (LiBr) are widely used in absorption refrigeration and heating systems. However, LiBr solutions can cause serious corrosion problems in structural materials (copper, steels, and other metals) in an absorption plant. The aim of the present work was the study of the corrosion rate of copper in 400 and 700 g/L (4.61 and 8.06 M) LiBr solutions pre-nitrogenous or pre-oxygenated at room temperature by immersion tests. The corroded copper concentration was determined with two techniques: weight-loss method and polarographic method. The corrosion curves of copper in LiBr solutions at room temperature as a function of the exposure time showed a similar tendency, and were fitted to a power function such as: C = kt{sup b}, where C was the corroded copper quantity per unit area (mg/cm{sup 2}), t was the exposure time (h), k was the corrosion coefficient, and b was the time exponent. From the corrosion coefficient values (k) it was deduced that the corrosion rate of copper in LiBr solutions at room temperature followed the order: 400 g/L (bubble of O{sub 2}) > 400 g/L (bubble of N{sub 2}) > 700 g/L (bubble of O{sub 2}) > 700 g/L (bubble of N{sub 2}). (authors)
15. Synthesis of zeolitic materials from volcanic ash in presence and absence of cetyltrimethylammonium bromide
Energy Technology Data Exchange (ETDEWEB)
Sanhueza N, V. M.; Bennun T, L. D., E-mail: vsanhuez@udec.cl [Universidad de Concepcion, Facultad de Ciencias Quimicas, Edmundo Larenas 129, Region del Biobio (Chile)
2015-07-01
Zeolitic materials as Na-phillipsite, Na-K-phillipsite-like zeolites and the mixtures of zeolites (phillipsite+analcime and phillipsite+chabazite+analcime) were synthesized from volcanic ash, either in presence and absence of cetiltrimetilamonium bromide (CTAB). The ash sample used in the laboratory experiments contains 75.36% SiO{sub 2} and 14.11% Al{sub 2}O{sub 3}, abundances. The reaction time as well as the influence of CTAB were studied in the zeolitic materials crystallization. The experiments were carried out under hydrothermal conditions, autogenic pressure and temperature of 150 grades C, as well as reaction time from 8 to 116 h. Products from this hydrothermal treatment were identified by X-ray diffraction (XRD) and characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (Sem-EDS). Of the zeolitic materials obtained the Na-K-phillipsite-like zeolite was found to be the most effective for the retention of cations Pb{sup 2+}, Zn{sup 2+} and Ba{sup 2+}. (Author)
16. Effectiveness of pinaverium bromide in the treatment of primitive biliary dyskinesia: 99mTc-P-IDA scintigraphic evaluation.
Science.gov (United States)
Scaffidi, A; Costa, R; Frontespezi, S
1987-09-01
The 99mTc-P-IDA (technetium-p-iminodiacetic acid) hepatocholangiocholecystoscintigraphy is a diagnostic technique which allows information on the liver biligenetic and excretory capabilities to be obtained. It is, moreover, a test that mirrors closely the anatomic and functional conditions of the cholecyst and choledochus. In this study the authors wanted to verify whether pinaverium bromide, a drug with a documented musculotropic-spasmolytic activity, was able to induce changes in some abnormal instrumental parameters observed in 24 subjects with primitive biliary dyskinesia. The results revealed that the ti values, characteristically longer in those subjects, were significantly reduced in the group of patients treated with pinaverium bromide. On the contrary, in the group of patients treated with placebo, there was no change with respect to this parameter. PMID:3316061
17. Vapor-liquid equilibria of the water + 1,3-propanediol and water + 1,3-propanediol + lithium bromide systems
Energy Technology Data Exchange (ETDEWEB)
Mun, S.Y.; Lee, H.
1999-12-01
Vapor-liquid equilibrium data of the water + 1,3-propanediol and water + 1,3-propanediol + lithium bromide systems were measured at 60, 160, 300, and 760 mmHg at temperatures ranging from 315 to 488 K. The apparatus used in this work is a modified still especially designed for the measurement of low-pressure VLE, in which both liquid and vapor are continuously recirculated. For the analysis of salt-containing solutions, a method incorporating refractometry and gravimetry was used. From the experimental measurements, the effect of lithium bromide on the VLE behavior of water + 1,3-propanediol was investigated. The experimental data of the salt-free system were successfully correlated using the Wilson, NRTL, and UNIQUAC models. In addition, the extended UNIQUAC model of Sander et al. was applied to the VLE calculation of salt-containing mixtures.
18. 6,6 '-bis (5,5,8,8-tetramethyl-5,6,7,8-tetra-hydro-benzo 1,2,4 triazine-3-yl) 2,2 ' bipyridine, an effective extracting agent for the separation of americium(III) and curium(III) from the lanthanides
International Nuclear Information System (INIS)
The extraction of americium(III), curium(III), and the lanthanides(III) from nitric acid by 6,6'- bis (5,5,8,8-tetramethyl-5,6,7,8-tetra-hydro-benzo[1,2,4]triazine-3-yl)-[2,2'] bipyridine (CyMe4-BTBP) has been studied. Since the extraction kinetics were slow, N,N'-dimethyl-N,N'-di-octyl-2-(2-hexyl-oxy-ethyl)malonamide (DMDOHEMA) was added as a phase transfer reagent. With a mixture of 0.01 M CyMe4-BTBP + 0.25 M DMDOHEMA in n -octanol, extraction equilibrium was reached within 5 min of mixing. At a nitric acid concentration of 1 M, an americium(III) distribution ratio of approx. 10 was achieved. Americium(III)/lanthanide(III) separation factors between 50 (dysprosium) and 1500 (lanthanum) were obtained. Whereas americium(III) and curium(III) were extracted as di-solvates, the stoichiometries of the lanthanide(III) complexes were not identified unambiguously, owing to the presence of DMDOHEMA. In the absence of DMDOHEMA, both americium(III) and europium(III) were extracted as di-solvates. Back-extraction with 0.1 M nitric acid was thermodynamically possible but rather slow. Using a buffered glycolate solution of pH=4, an americium(III) distribution ratio of 0.01 was obtained within 5 min of mixing. There was no evidence of degradation of the extractant, for example, the extraction performance of CyMe4-BTBP during hydrolysis with 1 M nitric acid did not change over a two month contact. (authors)
19. Palladium-Catalyzed α-Arylation of Aryl Acetic Acid Derivatives via Dienolate Intermediates with Aryl Chlorides and Bromides
OpenAIRE
Sha, Sheng-Chun; Zhang, Jiadi; Walsh, Patrick J.
2015-01-01
To date, examples of α-arylation of carboxylic acids remain scarce. Using a deprotonative cross-coupling process (DCCP), a method for palladium-catalyzed γ-arylation of aryl acetic acids with aryl halides has been developed. This protocol is applicable to a wide range of aryl bromides and chlorides. A procedure for the palladium-catalyzed α-arylation of styryl acetic acids is also described.
20. Efficacy of Tiotropium Bromide and Rehabilitation Treatment on Pulmonary Function of Patients With Sulfur Mustard Lung Injury
OpenAIRE
2015-01-01
Background: Chronic pulmonary complication is the most common delayed toxic effect of sulfur mustard (SM) and it has no treatment so far. Objectives: To evaluate short-term therapeutic effects of inhaled tiotropium bromide and pulmonary rehabilitation on pulmonary function of patients with SM induced lung injury. Patients and Methods: In a randomized clinical trial, using convenient sampling method, 54 patients with chronic lung disease due to SM exposure were recruited in Baqiyatallah Genera...
1. Impurity aggregation during radiation-stimulated decomposition of trimetaphosphate molecular centre in potassium bromide monocrystals. [Gamma radiation
Energy Technology Data Exchange (ETDEWEB)
Vasil' ev, I.A.; Mel' nikova, I.N.; Shibaev, V.A. (Leningradskij Tekhnologicheskij Inst. (USSR))
1984-05-01
On the basis of results of radiochemical and IR-spectrophotometric analyses, regularities of ..gamma..-radiolysis of trimetaphosphate molecular centre in potassium bromide matrix are found. Reactions most completely reflecting changes in the system under the effect of ionizing radiation are suggested. Computer-aided design has permitted to choose optimum values of rate constants for chemical reactions. Radiation-stimulated diffusion coefficient is estimated.
2. Palladium-Catalyzed Heck Coupling Reaction of Aryl Bromides in Aqueous Media Using Tetrahydropyrimidinium Salts as Carbene Ligands
Directory of Open Access Journals (Sweden)
İsmail Özdemir
2010-01-01
Full Text Available An efficient and stereoselective catalytic system for the Heck cross coupling reaction using novel 1,3-dialkyl-3,4,5,6-tetrahydropyrimidinium salts (1, LHX and Pd(OAc2 loading has been reported. The palladium complexes derived from the salts 1a-f prepared in situ exhibit good catalytic activity in the Heck coupling reaction of aryl bromides under mild conditions.
3. Effects of Soil and Water Content on Methyl Bromide Oxidation by the Ammonia-Oxidizing Bacterium Nitrosomonas europaea†
OpenAIRE
Duddleston, Khrystyne N.; Bottomley, Peter J; Porter, Angela; Arp, Daniel J.
2000-01-01
Little information exists on the potential of NH3-oxidizing bacteria to cooxidize halogenated hydrocarbons in soil. A study was conducted to examine the cooxidation of methyl bromide (MeBr) by an NH3-oxidizing bacterium, Nitrosomonas europaea, under soil conditions. Soil and its water content modified the availability of NH4+ and MeBr and influenced the relative rates of substrate (NH3) and cosubstrate (MeBr) oxidations. These observations highlight the complexity associated with characterizi...
4. Delivery of albuterol and ipratropium bromide from two nebulizer systems in chronic stable asthma. Efficacy and pulmonary deposition
International Nuclear Information System (INIS)
Bronchodilator responses to both nebulized albuterol (salbutamol) and ipratropium bromide and aerosol delivery to the tracheobronchial tree have been assessed in eight patients with chronic stable asthma (mean baseline FEV1, 50 percent; reversibility greater than 20 percent). Two commercially available nebulizer systems were used, namely, a Turret nebulizer operated at a compressed gas flow rate of 12 L/min (droplet MMD, 3.3 mu) and an Inspiron nebulizer driven at 6 L/min (MMD, 7.7 mu). Albuterol was given as doses of 250 micrograms, 250 micrograms, 500 micrograms, and 1,000 micrograms (cumulative dose, 2 mg) and ipratropium bromide as doses of 50 micrograms, 50 micrograms, 100 micrograms, and 200 micrograms (cumulative dose, 400 micrograms) at intervals of 35 minutes. For albuterol, bronchodilatation was significantly (p less than 0.05) greater at all dosage levels with the Turret. For ipratropium, bronchodilatation was similar for both nebulizers. Measurements of aerosol deposition using 99mTc-labelled pentetic acid (diethylenetriamine pentaacetic acid; DTPA) showed that 9.1 +/- 1.1 percent and 2.7 +/- 0.2 percent of the dose reached the lungs during nebulization to dryness for Turret and Inspiron, respectively (p less than 0.01); distribution within the lungs was similar for the two aerosols. Selection of nebulizer apparatus can influence delivery of aerosol and subsequent bronchodilator response to albuterol in patients with chronic stable asthma but is less important for aerosol delivery of ipratropium bromide in these patients
5. Dual-permeability modeling of preferential bromide leaching from a tile-drained glacial till agricultural field
Science.gov (United States)
Gerke, Horst H.; Maximilian Köhne, J.
2004-04-01
A tile-drained agricultural field can be regarded as a 'field-scale' lysimeter that may be used to study soil water and chemical transport under relatively natural conditions. Tile discharge and effluent bromide concentrations measured in a previous field tracer experiment for a structured clayey loam at Bokhorst, Northern Germany, indicated strong preferential flow. Simulation using single domain HYDRUS numerical flow and transport model could nevertheless explain water outflow, however, completely failed to describe tile-drain leaching patterns of the conservative tracer. The objective of this paper was to analyze whether the nonequilibrium-type dual-permeability model concept could better capture soil structure related principle mechanisms of preferential leaching in the unsaturated soil at that study site. The dual-permeability model (DUAL) describes for soil matrix and fracture pore systems Darcian flow with coupled Richards' equations and convective-dispersive (CD) solute transport with coupled CD equations. The hydraulic parameters of the dual-permeability model were obtained from standard soil hydraulic measurements by adopting a bimodal fitting procedure, whereas transport parameters were inferred from soil column tracer experiments and geometrical transfer term parameters were derived using qualitative soil structure descriptions. The hydraulic conductivity Ka in the inter-domain water transfer term and the effective diffusion coefficient Da in the solute mass transfer term were calibrated by comparing simulated with measured tile flow and effluent concentrations. The DUAL approach described water flow similarly well as the single-domain model. Bromide concentrations in the tile effluent could be approximated with DUAL when decreasing the Ka and Da values by three orders of magnitude compared with the values of the soil matrix domain. The dual-permeability approach seems to reflect nonequilibrium transport mechanisms at this structured soil since it not
6. The effect of ethidium bromide and chloramphenicol on mitochondrial biogenesis in primary human fibroblasts
Energy Technology Data Exchange (ETDEWEB)
Kao, Li-Pin; Ovchinnikov, Dmitry; Wolvetang, Ernst, E-mail: e.wolvetang@uq.edu.au
2012-05-15
The expression of mitochondrial components is controlled by an intricate interplay between nuclear transcription factors and retrograde signaling from mitochondria. The role of mitochondrial DNA (mtDNA) and mtDNA-encoded proteins in mitochondrial biogenesis is, however, poorly understood and thus far has mainly been studied in transformed cell lines. We treated primary human fibroblasts with ethidium bromide (EtBr) or chloramphenicol for six weeks to inhibit mtDNA replication or mitochondrial protein synthesis, respectively, and investigated how the cells recovered from these insults two weeks after removal of the drugs. Although cellular growth and mitochondrial gene expression were severely impaired after both inhibitor treatments we observed marked differences in mitochondrial structure, membrane potential, glycolysis, gene expression, and redox status between fibroblasts treated with EtBr and chloramphenicol. Following removal of the drugs we further detected clear differences in expression of both mtDNA-encoded genes and nuclear transcription factors that control mitochondrial biogenesis, suggesting that the cells possess different compensatory mechanisms to recover from drug-induced mitochondrial dysfunction. Our data reveal new aspects of the interplay between mitochondrial retrograde signaling and the expression of nuclear regulators of mitochondrial biogenesis, a process with direct relevance to mitochondrial diseases and chloramphenicol toxicity in humans. -- Highlights: ► Cells respond to certain environmental toxins by increasing mitochondrial biogenesis. ► We investigated the effect of Chloramphenicol and EtBr in primary human fibroblasts. ► Inhibiting mitochondrial protein synthesis or DNA replication elicit different effects. ► We provide novel insights into the cellular responses toxins and antibiotics.
7. Application of artificial neural network in 3D imaging with lanthanum bromide calorimeter
Science.gov (United States)
Gostojic, A.; Tatischeff, V.; Kiener, J.; Hamadache, C.; Karkour, N.; Linget, D.; Grave, X.; Gibelin, L.; Travers, B.; Blin, S.; Barrillon, P.
2015-07-01
Gamma-ray astronomy in the energy range from 0.1 up to 100 MeV holds many understudied questions connected with e.g. stellar nucleosynthesis, the active Sun, neutron stars and black holes. To access the physics behind, a significant improvement in detection sensitivity is needed compared to previous missions, e.g. CGRO and INTEGRAL. One of the promising concepts for a future gamma-ray mission is an Advanced Compton Telescope. Under the project of creating a prototype of such instrument, we study the perspectives of using a novel inorganic scintillator as a calorimeter part. Modern inorganic crystal or ceramics scintillators are constantly improving on qualities such as energy resolution and radiation hardness, and this makes them a smart choice for a new space-borne telescope. At CSNSM Orsay, we have assembled a detection module from a 5 × 5cm2 area and 1 cm thick, cerium-doped lanthanum (III) bromide (LaBr3:Ce) inorganic scintillator coupled to a 64 channel multi-anode photomultiplier. The readout of the PMT signals is carried out with the ASIC MAROC, used previously for the luminometer of the ATLAS detector (CERN). Characterization, thorough measurements with various radioactive sources, as well as, single photoelectron detection have been done. Furthermore, we made a comparison of measurements with a detailed GEANT4-based simulation which includes tracking of the optical photons. Finally, we have studied the 3D reconstruction of the first interaction point of incident gamma rays, utilizing a neural network algorithm. This spatial position resolution plays a crucial part in the future implementations and, together with the other measured properties, it makes our detector module very interesting for the next generation of space telescopes operating in the MeV range.
8. Degradation of methyl bromide by methanotrophic bacteria in cell suspensions and soils
Science.gov (United States)
Oremland, R.S.; Miller, L.G.; Culbertson, C.W.; Connell, T.L.; Jahnke, L.
1994-01-01
Cell suspensions of Methylococcus capsulatus mineralized methyl bromide (MeBr), as evidenced by its removal from the gas phase, the quantitative recovery of Br- in the spent medium, and the production of 14CO2 from [14C]MeBr. Methyl fluoride (MeF) inhibited oxidation of methane as well as that of [14C]MeBr. The rate of MeBr consumption by cells varied inversely with the supply of methane, which suggested a competitive relationship between these two substrates. However, MeBr did not support growth of the methanotroph. In soils exposed to high levels (10,000 ppm) of MeBr, methane oxidation was completely inhibited. At this concentration, MeBr removal rates were equivalent in killed and live controls, which indicated a chemical rather than biological removal reaction. At lower concentrations (1,000 ppm) of MeBr, methanotrophs were active and MeBr consumption rates were 10-fold higher in live controls than in killed controls. Soils exposed to trace levels (10 ppm) of MeBr demonstrated complete consumption within 5 h of incubation, while controls inhibited with MeF or incubated without O2 had 50% lower removal rates. Aerobic soils oxidized [14C]MeBr to 14CO2, and MeF inhibited oxidation by 72%. Field experiments demonstrated slightly lower MeBr removal rates in chambers containing MeF than in chambers lacking MeF. Collectively, these results show that soil methanotrophic bacteria, as well as other microbes, can degrade MeBr present in the environment.
9. The developmental toxicity of 1-methyl-3-octylimidazolium bromide on Daphnia magna.
Science.gov (United States)
Luo, Yan-Rui; Li, Xiao-Yu; Chen, Xiao-Xiao; Zhang, Bang-Jun; Sun, Zhen-Jun; Wang, Jian-Ji
2008-12-01
The developmental toxicity of 1-methyl-3-octylimidazolium bromide ([C(8)mim]Br) on Daphnia magna was investigated. The 24 and 48 h LC(50) values for [C(8)mim]Br in D. magna were 1.99 and 0.95 mg/L, respectively. A series of multigenerational toxicity tests were then used to explore [C(8)mim]Br effects in D. magna. [C(8)mim]Br significantly inhibited the body lengths of the F0 and F1 1st generations. After 21 days of exposure, [C(8)mim]Br lowered the reproductive ability of the F0 and F1 1st generations. In F1 3rd generation, 21 days of [C(8)mim]Br exposure prolonged the time to bear the first egg and the time to the first brood compared with the control, but the number of first-brood offspring and the number of broods produced by these animals were reduced. After the recovery period all the reproductive parameters returned to normal in F1 1st generation except for the number of broods. The dead neonates increased with prolonged exposure and increasing concentrations, and the dead neonates of the F1 3rd generation went far beyond that of the F1 1st and F0 generations. The intrinsic rate of natural increase (r) values of the three D. magna generations significantly decreased after exposure to higher concentrations of [C(8)mim]Br compared with control groups. Collectively, these results suggest that [C(8)mim]Br exerts a toxic effect on the development of D. magna. This study also highlights the importance of systematically evaluating the potential effects of aquatic ecosystems of ionic liquids that may be released into bodies of water. PMID:18442076
10. Transport of atrazine versus bromide and δO18 in sand
Science.gov (United States)
Tindall, James A.; Friedel, Michael J.
2016-01-01
The objective of this research was to determine the process of atrazine transport compared to bromide and δO18 transport in sands near Denver. Three 1.5 × 2 × 1.5-m plots were installed and allowed to equilibrate for 2 years before research initiation and were instrumented with 1.5 × 2-m zero-tension pan lysimeters installed at 1.5-m depths. Additionally, each plot was instrumented with suction lysimeters, tensiometers, time domain reflectometry (TDR) moisture probes, and thermocouples (to measure soil temperature) at 15-cm depth increments. All plots were enclosed with a raised frame (of 8-cm height) to prevent surface runoff. During the 2-year period before research began, all suction and pan lysimeters were purged monthly and were sampled for fluids immediately prior to atrazine and KBr application to obtain background concentrations. Atrazine illustrated little movement until after a significant rainfall event, which peaked concentrations at depths of about 90 to 135 cm. Both Br− and δO18 moved rapidly through the soil, probably owing to soil porosity and anion exclusion for Br−. Concentrations of atrazine exceeding 5.0 μL−1 were observed with depth (90 to 150 cm) after several months. It appears that significant rainfall events were a key factor in the movement of atrazine in the sand, which allowed the chemicals to move to greater depths and thus avoid generally found biodegradation processes.
11. Performance characteristics of single effect lithium bromide/ water absorption chiller for small data centers
Science.gov (United States)
Mysore, Abhishek Arun Babu
A medium data center consists of servers performing operations such as file sharing, collaboration and email. There are a large number of small and medium data centers across the world which consume more energy and are less efficient when compared to large data center facilities of companies such as GOOGLE, APPLE and FACEBOOK. Such companies are making their data center facilities more environmental friendly by employing renewable energy solutions such as wind and solar to power the data center or in data center cooling. This not only reduces the carbon footprint significantly but also decreases the costs incurred over a period of time. Cooling of data center play a vital role in proper functioning of the servers. It is found that cooling consumes about 50% of the total power consumed by the data center. Traditional method of cooling includes the use of mechanical compression chillers which consume lot of power and is not desirable. In order to eliminate the use of mechanical compressor chillers renewable energy resources such as solar and wind should be employed. One such technology is solar thermal cooling by means of absorption chiller which is powered by solar energy. The absorption chiller unit can be coupled with either flat plate or evacuated tube collectors in order to achieve the required inlet temperature for the generator of the absorption chiller unit. In this study a modular data center is considered having a cooling load requirement of 23kw. The performance characteristics of a single stage Lithium Bromide/ water refrigeration is presented in this study considering the cooling load of 23kw. Performance characteristics of each of the 4 heat exchangers within the unit is discussed which helps in customizing the unit according to the users' specific needs. This analysis helps in studying the importance of different properties such as the effect of inlet temperatures of hot water for generator, inlet temperatures of cooling water for absorber and
12. Antibacterial activity of starch/acrylamide/allyl triphenyl phosphonium bromide copolymers synthesized by gamma irradiation
International Nuclear Information System (INIS)
Starch/acrylamide/allyl triphenyl phosphonium bromide (St/AM/TP) copolymers were synthesized by simultaneous gamma irradiation and characterized by FTIR and 1H NMR techniques, weight measurement and titration method. Moreover, their antibacterial activities against Staphylococcus aureus were explored by the viable cell counting method in sterile distilled water. At St/AM/TP 6:8.4:5.6 g, copolymers with higher graft ratio (G) and higher (AM+TP) graft efficiency (EAM+TP) were obtained at 3 and 6 kGy, while cationic degree (CD) and TP graft efficiency (ETP) continuously increased with absorbed dose from 1 to 6 kGy. All of the copolymers were capable of killing >99.75% of 107 CFU/ml S. aureus within 30 mins. Moreover, at 3 kGy, G, EAM+TP and ETP increased with AM/TP from 0:14 to 11.2:2.8 g at St/(AM+TP) 6:14 g, while the optimum CD and antibacterial activity were achieved at AM/TP 7:7 and 8.4:5.6 g. In addition, at 3 kGy, G, EAM+TP and CD increased with St/(AM+TP) from 6:3 to 6:18 g at AM/TP 8.4:5.6 g, while the optimum antibacterial activity was achieved at 6:10 to 6:18 g, and the optimum ETP was achieved at 6:14. - Highlights: • Cationic starch is prepared from AM and TP by Gamma irradiation. • Cationic starch is characterized by FTIR, NMR, weight method and titration method. • Grafting ratio and cationic degree depend on absorbed dose and composition. • Cationic starch shows good antibacterial activity against Staphylococcus aureus
13. Sol-gel Transition of Methylcellulose Solution in the Coexistence of Hexadecyltrimethylammonium Bromide and Sodium Chloride
Institute of Scientific and Technical Information of China (English)
Shah Zhou; Hai-yang Yang; Yong-jun Xie; Hua-zhen Li; Guang-ming Liu
2011-01-01
The sol-gel transition of methylcellulose (MC) solution in the presence of NaCl and hexadecyltrimethylammonium bromide (HTAB),together with MC/NaCl solution in the presence of HTAB and MC/HATB solution in the presence of NaCl,was investigated by the rheological measurements.It has been found that the sol-gel transition temperature of MC solution decreases linearly with the concentration of NaCl in solution but increases linearly with the concentration of HTAB in solution,respectively.However,the sol-gel transition temperature of MC/NaCl solution in the presence of HTAB keeps the same value,independent of the concentration of HTAB in solution.On the other hand,the sol-gel transition temperature of MC/HTAB solution decreases linearly with the concentration of NaCl in solution.The experimental results suggest that,for MC/NaCl solution in the presence of HTAB,the saltinduced spherical micelles of HTAB should have formed in bulk solution.For MC solution in the absence of NaCl,no spherical micelles have been formed in bulk solution,though the concentration of HTAB in our experiment is almost one order of magnitude higher than the critical micelle concentration of HTAB in polymer-free solution.In fact,due to adsorption of HTAB on MC chains,the realconcentration of HTAB in bulk solution,is much less than the apparent concentration of HTAB dissolved in MC solution.
14. Spectroscopic study on the interaction of Bacillus subtilis α-amylase with cetyltrimethylammonium bromide
International Nuclear Information System (INIS)
The interaction between α-amylase from Bacillus subtilis and cetyltrimethylammonium bromide (CTAB) has been investigated at various temperature conditions using fluorescence and circular dichroism (CD) spectroscopic methods. Fluorescence data revealed that the fluorescence quenching of α-amylase by CTAB is the result of complex formation between CTAB and α-amylase. The thermodynamic analysis on the binding interaction data shows that the interactions are strongly exothermic (ΔHo=-17.92 kJ mol-1) accompanied with increase in entropy (ΔSo between 109 to 135 J mol-1 K-1). Thus the binding of CTAB to α-amylase is both enthalpic and entropic driven, which represent the predominate role of both electrostatic and hydrophobic interactions in complex formation process. The values of 2.17x10-3 M-1 and 1.30 have been obtained from associative binding constant (Ka) and stoichiometry of binding number (n), from analysis of fluorescence data, respectively. Circular dichroism spectra showed the substantial conformational changes in secondary structure of α-amylase due to binding of CTAB, which represents the complete destruction of both secondary and tertiary structure of α-amylase by CTAB. - Research highlights: → The Fluorescence quenching effect of α-amylase by CTAB is a consequence of formation α-amylase-CTAB complex. → The α-helical analyzing from the CD spectra in the various concentration of CTAB shows strongly deformation of α-amylase. → Thermodynamic analysis of quenching verify that the interactions are both enthalpy and entropic driven.
15. Temperature effect on the transport of bromide and E. coli NAR in saturated soils
Science.gov (United States)
2015-03-01
In this study we investigated the transport of nalidixic acid-resistant Escherichia coli (E. coli NAR) and bromide (Br-) through two soils, a sandy loam (SL) and clay loam (CL). Soils were repacked in columns (45 cm length × 22 cm diameter) and subjected to physical (freeze/thaw, and wet/dry cycles) and biological (by earthworms, Eisenia fetida) weathering for 12 months. Saturated flow conditions were maintained using a tension infiltrometer. Tests were carried out at either 5 or 20 °C. After steady-state flow conditions were established, a suspension containing E. coli NAR and Br- was sprayed onto the surface of soil columns. Leachate was sampled at three depths, 15, 30 and 45 cm. Time to maximum concentration (Cmax) of E. coli NAR was greater for SL at all depths. Both tracers had rapid breakthrough curves (BTCs) shortly after the suspension injection followed by prolonged tailing indicating the presence of preferential pathways and thus soil heterogeneity regenerated after the induced physical and biological weathering. About 40% of the E. coli NAR and 79% of the Br- leached through the entire 45 cm soil columns during the experiments. Leaching with cold water (5 °C) led to lower hydraulic conductivity and flow rate and consequently enhanced bacterial filtration for both soils. Very low values for the detachment coefficient for E. coli NAR at 5 °C suggest an irreversible process of bacterial attachment in heterogeneous soils. BTCs were well described by the mobile-immobile model (MIM) in HYDRUS-1D. Soil texture/structure and temperature had a significant effect on the model's fitted parameters.
16. A comparison of the use of sodium iodide and lanthanum bromide scintillation crystals for airborne surveys
Science.gov (United States)
Bailey, Derek M.
The Environmental Protection Agency (EPA) Aerial Spectral Environmental Collection Technology (ASPECT) program performs aerial radiological and chemical characterization of geographical regions of interest. Airborne surveys are performed to characterize environmental radionuclide content, for mineral exploration, as well as for emergency scenarios such as major releases or lost sources. Two radiological detection systems are used by the ASPECT team for gamma-ray detection and characterization: lanthanum bromide [LaBr 3(Ce)] and sodium iodide [NaI(Tl)] scintillation systems. An aerial survey of a uranium mine in the western United States was performed using both NaI(Tl) and LaBr3(Ce) detection systems. Analyses of the survey data were performed with RadAssist software and applying International Atomic Energy Agency (IAEA) airborne gamma ray mapping guidelines. The data for the survey were corrected for cross-over, which is spectral interference from higher energy photons as a result of Compton scattering, height attenuation, cosmic ray contribution to signal, and Radon contribution to signal. Two radiation survey contours were generated from each discrete data set. Based on analysis of the uranium mine survey results, LaBr3(Ce) produced a product comparable to that of NaI(Tl). The LaBr3(Ce) detection system contained 1/16th the scintillating volume and had a total system weight that was 1/4th that of the NaI(Tl) system. LaBr3(Ce) demonstrated a clear advantage over NaI(Tl) detectors in system mobility, and weight factors in airborne gamma ray spectroscopy.
17. Rearrangement reaction of the hydroxyl group of ω-hydroxy-alkyltriphenyl phosphonium bromides
Institute of Scientific and Technical Information of China (English)
何美玉; 袁谷; 贺晓然
2000-01-01
No molecular ion peak from the Electron Impact Ionization of eight ω-hydroxyalkyltriphenyl phosphonium bromides (Ph3P+ (CH2)nOHBr, n = 2-6, 8--10) can be found, except a part of some relative powerful fragment ions can be observed only. Each c ompound forms a very characteristic ion (O= PPh3- 1)+ atm/z 277throughhydryl rearrangement reaction. The intensity of this ion is closely related with the size of the carbon chain of hydroxyalkyl and with temperature of ion source and temperature of sample probe. The above rearrangement reaction and the reaction to form ion at m/ z 262 take place simultaneonsly, thus leading to strong competition.At n =2, ion at m/z 277 is the most powerful and becomes continuously the base peak. At n = 3 and n = 4, the intensity of ion at m/z 262 reaches the maximum, and is always the base peak, and the relative abundance of m/z 277 is only around 2%. At n = 5, 6, 8, 9, 10, m/z 277 becomes base peak when the temperature of probe is below 300°C. But, when the temperature increases from 300°C to 350°C, m/z 262 suddenly becomes the base peak, which is not in direct proportional relation with the size of carbon chain. It is proved by MIKES and accurate mass that ion at m/z 277 produces a fragment ion (O= PPh2-2)+ at m/z 199 with the loss of the neutral benzene molecule.
18. Spectroscopic study on the interaction of Bacillus subtilis {alpha}-amylase with cetyltrimethylammonium bromide
Energy Technology Data Exchange (ETDEWEB)
Omidyan, R., E-mail: r.omidyan@sci.ui.ac.i [Department of Chemistry, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731 (Iran, Islamic Republic of); Kazemi, S.H. [Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731 (Iran, Islamic Republic of); Bordbar, A.K. [Department of Chemistry, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Zaynalpour, S. [Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731 (Iran, Islamic Republic of)
2011-06-15
The interaction between {alpha}-amylase from Bacillus subtilis and cetyltrimethylammonium bromide (CTAB) has been investigated at various temperature conditions using fluorescence and circular dichroism (CD) spectroscopic methods. Fluorescence data revealed that the fluorescence quenching of {alpha}-amylase by CTAB is the result of complex formation between CTAB and {alpha}-amylase. The thermodynamic analysis on the binding interaction data shows that the interactions are strongly exothermic ({Delta}H{sup o}=-17.92 kJ mol{sup -1}) accompanied with increase in entropy ({Delta}S{sup o} between 109 to 135 J mol{sup -1} K{sup -1}). Thus the binding of CTAB to {alpha}-amylase is both enthalpic and entropic driven, which represent the predominate role of both electrostatic and hydrophobic interactions in complex formation process. The values of 2.17x10{sup -3} M{sup -1} and 1.30 have been obtained from associative binding constant (K{sub a}) and stoichiometry of binding number (n), from analysis of fluorescence data, respectively. Circular dichroism spectra showed the substantial conformational changes in secondary structure of {alpha}-amylase due to binding of CTAB, which represents the complete destruction of both secondary and tertiary structure of {alpha}-amylase by CTAB. - Research highlights: {yields} The Fluorescence quenching effect of {alpha}-amylase by CTAB is a consequence of formation {alpha}-amylase-CTAB complex. {yields} The {alpha}-helical analyzing from the CD spectra in the various concentration of CTAB shows strongly deformation of {alpha}-amylase. {yields} Thermodynamic analysis of quenching verify that the interactions are both enthalpy and entropic driven.
19. Impact of the cation distribution homogeneity on the americium oxidation state in the U0.54Pu0.45Am0.01O2-x mixed oxide
Science.gov (United States)
Vauchy, Romain; Robisson, Anne-Charlotte; Martin, Philippe M.; Belin, Renaud C.; Aufore, Laurence; Scheinost, Andreas C.; Hodaj, Fiqiri
2015-01-01
The impact of the cation distribution homogeneity of the U0.54Pu0.45Am0.01O2-x mixed oxide on the americium oxidation state was studied by coupling X-ray diffraction (XRD), electron probe micro analysis (EPMA) and X-ray absorption spectroscopy (XAS). Oxygen-hypostoichiometric Am-bearing uranium-plutonium mixed oxide pellets were fabricated by two different co-milling based processes in order to obtain different cation distribution homogeneities. The americium was generated from β- decay of 241Pu. The XRD analysis of the obtained compounds did not reveal any structural difference between the samples. EPMA, however, revealed a high homogeneity in the cation distribution for one sample, and substantial heterogeneity of the U-Pu (so Am) distribution for the other. The difference in cation distribution was linked to a difference in Am chemistry as investigated by XAS, with Am being present at mixed +III/+IV oxidation state in the heterogeneous compound, whereas only Am(IV) was observed in the homogeneous compound. Previously reported discrepancies on Am oxidation states can hence be explained by cation distribution homogeneity effects.
20. Fabrication of targets for transmutation of americium : synthesis of inertial matrix by sol-gel method. Procedure study on the infiltration of a radioactive solutions
International Nuclear Information System (INIS)
addition a new and unexpected phase formed by the reaction of americium with spinel during the high temperature synthesis process has been identified. This new phase could provide a unique menas to stabilise Am in one particular oxidation state. (Author)
1. Sorption and diffusion of cobalt, nickel, strontium, iodine, cesium and americium in natural fissure surfaces and drill core cups studied by autoradiography, 3
International Nuclear Information System (INIS)
This report summarizes the studies on sorption and diffusion of Cs, Sr, Co, Ni, Am and I in common rocks in Finnish bedrock carried out in laboratory experiments. Samples used in these studies were sections of drill cores containing filled and unfilled natural fracture surfaces and drill cores with a diamond drilled longitudinal cavity in the middle of the sample (drill core cups). Samples originated from the two nuclear power plant sites in Finland: tonalite and mica gneiss from Olkiluoto in Eurajoki and rapakivi granite from Haestholmen in Loviisa. The water used in the experiments was synthetic groundwater spiked at a time with one of the radionuclides: Cs-134, Sr-90, Co-60, Ni-63, Am-241 and I-125. Contact times from one week to one year were used to evaluate time dependence of diffusion. An autoradiographic method was used for determination of the penetration depths and diffusion pathways of elements. For determination of diffusion coefficients a quantitative computerized autoradiographic method was used to get the concentration profiles of the radionuclides in the drill cores. Sorption on natural fracture surfaces was more effective than on freshly drilled core samples. Filling materials on natural fracture surfaces, except calcite, increased sorption. The distribution coefficients for drill core cups were about the same as those for unfilled natural fracture surfaces after a contact time of one week and the sorption tendency of radionuclides was: Ka(Cs) > Ka(Co) > Ka(Am) > Ka(Ni) > Ka(Sr) > Ka(I). Radionuclides were observed to penetrate into fissures of the rock matrix and high-capacity minerals. Strontium was found as far as 35 mm in a filled natural fracture surface sample of rapakivi granite after a contact time of one year. The corresponding values were 3.0 mm for cesium, 2.1 mm for cobalt and 2.6 mm for nickel. For americium no diffusion could be observed (a-values for strontium was 6.6 x 10-16-1.1 x 10-13 m2/s, for cesium 4.7 x 10-16-7.2 x 10-15 m2/s
2. Separation by sequential chromatography of americium, plutonium and neptunium elements: application to the study of trans-uranian elements migration in a European lacustrine system
International Nuclear Information System (INIS)
The nuclear tests carried out in the atmosphere in the Sixties, the accidents and in particular that to the power station of Chernobyl in 1986, were at the origin of the dispersion of a significant quantity of transuranic elements and fission products. The study of a lake system, such that of the Blelham Tarn in Great Britain, presented in this memory, can bring interesting answers to the problems of management of the environment. The determination of the radionuclides in sediment cores made it possible not only to establish the history of the depositions and consequently the origin of the radionuclides, but also to evaluate the various transfers which took place according to the parameters of the site and the properties of the elements. The studied transuranic elements are plutonium 238, 239-240, americium 241 and neptunium 237. Alpha emitting radionuclides, their determination requires complex radiochemical separations. A method was worked out to successively separate the three radioelements by using a same chromatographic column. Cesium 137 is the studied fission product, its determination is done by direct Gamma spectrometry. Lead 210, natural radionuclide, whose atmospheric flow can be supposed constant. makes it possible to obtain a chronology of the various events. The detailed vertical study of sediment cores showed that the accumulation mode of the studied elements is the same one and that the methods of dating converge. The cesium, more mobile than transuranic elements in the atmosphere, was detected in the 1963 and 1986 fallout whereas an activity out of transuranic elements appears only for the 1963 fallout. The activity of the 1963 cesium fallout is of the same order of magnitude as that of 1986. The calculation of the diffusion coefficients of the elements in the sediments shows an increased migration of cesium compared to transuranic elements. An inventory on the whole of the lake made it possible to note that the atmospheric fallout constitute the
3. Direct injection, simple and robust analysis of trace-level bromate and bromide in drinking water by IC with suppressed conductivity detection.
Science.gov (United States)
Lawal, Wasiu; Gandhi, Jay; Zhang, Chunlong Carl
2010-08-01
Bromide is ubiquitously found in drinking water. It is introduced into source water primarily by contact with bromide-containing soils or seawater having high bromide content. Bromide is converted into carcinogenic bromate during ozonation processes employed in some drinking water and wastewater treatment plants. Therefore, monitoring of bromate in drinking water and its precursor bromide in source water is required. The purpose of this study was to survey bromide and bromate concentrations in randomly selected bottle waters of various brands and several tap water samples in the coastal Houston area using a direct-injection ion chromatography (IC) and a suppressed conductivity system. The method employs a simple isocratic IC with loop injection with calculated detection limit of 0.009 microg/L for bromate and 0.028 microg/L for bromide (250-microL sample volume). Allowing the detection of both species at the microg/L level in drinking water, this method does not require specialized instrumentation such as two-dimensional IC, expensive sample preparation, or post-column reactions. The results show that, whereas bromate remains undetected in all five tap water samples, there are significant high concentrations of bromide in the coastal Houston area (294.79 +/- 56.97 microg/L). Its link to potential seawater intrusion need to be further investigated. For bottle water samples randomly collected, 18.2% (2 out of 11) showed detectable amount of both bromide and bromate. The detection of bromate coincides with those bottle water samples that underwent ozonation treatment. Further sample campaign with exclusively ozonated bottle water samples (n = 19) showed 100% detection rate for both bromide and bromate. The 99% confidence intervals were 14.45-37.97 microg/L and 0.32-2.58 microg/L for bromide and bromate, respectively. The highest level of bromate among all ozonated bottle water samples was 7.57 microg/L, a concentration close to the U.S. EPA prescribed limit for
4. Modelling the site of bromide binding in vanadate-dependent bromoperoxidases.
Science.gov (United States)
Kraehmer, Verena; Rehder, Dieter
2012-05-01
Treatment of Boc-protected (S)-serine (Ser) methyl ester with triphenylphosphine bromide Ph(3)PBr (intermittently generated from PPh(3) and N-bromosuccinimide) yields Boc-3-bromoalanine (R)-Boc-BrAlaMe and, after deprotection, bromoalanine methyl ester (R)-BrAlaMe in the form of its hydrobromide. Boc-BrAlaMe and BrAlaMe have been structurally characterised. The reaction between BrAlaMe, salicylaldehyde (sal) and VO(2+) results in the formation of Schiff base complexes of composition [VO(sal-BrAlaMe)solv](+) (solv = CH(3)OH: 3, THF: 5) and [VO(sal-BrAla)THF] 4. DFT calculations of the structures of 3, 4 and 5, based on the B3LYP functional and employing the triple zeta basis set 6-311++g(d,p), provide distances Br···V = 4.0 ± 0.1 Å, if some distortion of the dihedral angle ∠N-C-C-Br is allowed (affording a maximum energy of ca. 45 kJ mol(-1)), and thus model Br···V distances detected by X-ray methods in bromoperoxidases from the marine algae Ascophyllum nodosum and Corallina pilulifera. The DFT calculations have been validated by comparing calculated and found structures, including the new complex [V(V)O(Amp-sal)OMe(MeOH)] (1, Amp is the aminophenol moiety) and the known complex [VO(L-Ser-van)H(2)O] (van = vanillin). Additional validation has been undertaken by checking experimental against calculated (BHandHLYP) EPR spectroscopic hyperfine coupling constants. Complexes containing bromine as a substituent at the phenyl moiety of a Schiff base ligand do not allow for an appropriate simulation of the Br···V distance in peroxidases. The closest agreement, d(Br···V) = 4.87 Å, is achieved with [VO(3Br-salSer)THF] (6), where 3Brsal-Ser is the dianionic Schiff base formed between 3-Br-5-NO(2)-salicylaldehyde and serine. PMID:22415551
5. Formation of bromate during ferrate(VI) oxidation of bromide in water.
Science.gov (United States)
Huang, Xin; Deng, Yang; Liu, Shuang; Song, Yali; Li, Nanzhu; Zhou, Jizhi
2016-07-01
Ferrate (VI) is traditionally recognized as a safe oxidant without production of disinfection byproducts (DBPs). However, here we detected probable carcinogenic bromate (BrO3(-)) during ferrate(VI) oxidation of bromide (Br(-))-containing water, and evaluated the effects of pH, ferrate(VI) dose, initial Br(-) concentration, and co-existing anions on the BrO3(-) formation. BrO3(-) was produced at a moderately-weakly acidic pH condition and in the absence of phosphate that was commonly applied as a buffer and stabilizing agent in previous ferrate(VI) studies. At pH 5.0, the produced BrO3(-) was increased from 12.5 to 273.8 μg/L with the increasing initial Br(-) concentration from 200 to 1000 μg/L at 10 mg/L Fe(VI), corresponding to an increase in the molar conversion ([BrO3(-)]/initial [Br(-)]) from 2.3% to 10.3%, in a bicarbonate-buffered solution. As pH increased to 7.0, the BrO3(-) concentration gradually dropped. The BrO3(-) production appeared to be associated with the oxidation by high valence iron species (i.e. Fe(VI), Fe(V) and Fe(IV)). Two key intermediate products (i.e. hypobromous acid/hypobromite (HOBr/OBr(-)) and hydrogen peroxide (H2O2)) relevant to the bromate formation were identified. The production of HOBr, a requisite intermediate for the ensuing bromate formation, was indirectly validated through identification of bromine-containing trihalomethanes and haloacetic acids during ferrate oxidation in a natural water, though these bromo-organic DBPs produced were insignificant. Furthermore, the inhibition effects of various anions on the formation of BrO3(-) followed chloride H2O2 was detected at higher phosphate concentration. It could reduce HOBr to Br(-), thereby inhibiting the bromate formation. PMID:27153235
6. Effect of pinaverium bromide on stress-induced colonic smooth muscle contractility disorder in rats
Institute of Scientific and Technical Information of China (English)
Yun Dai; Jian-Xiang Liu; Jun-Xia Li; Yun-Feng Xu
2003-01-01
AIM: To investigate the effect of pinaverium bromide, a Ltype calcium channel blocker with selectivity for the gastrointestinal tract on contractile activity of colonic circular smooth muscle in normal or cold-restraint stressed rats and its possible mechanism.METHODS: Cold-restraint stress was conducted on rats to increase fecal pellets output. Each isolated colonic circular muscle strip was suspended in a tissue chamber containing warm oxygenated Tyrode-Ringer solution. The contractile response to ACh or KCl was measured isometrically on inkwriting recorder. Incubated muscle in different concentrations of pinaverium and the effects of pinaverium were investigated on ACh or KCl-induced contraction. Colon smooth muscle cells were cultured from rats and [Ca2+]i was measured in cell suspension using the Ca2+ fluorescent dye fura-2/AlMl.RESULTS: During stress, rats fecal pellet output increased 61% (P＜0.01). Stimulated with ACh or KCl, the muscle contractility was higher in stress than that in control. Pinaverium inhibited the increment of [Ca2+]i and the muscle contraction in response to ACh or KCl in a dose dependent manner. A significant inhibition of pinaverium to ACh or KCl induced [Ca2+]i increment was observed at 10-6 mol/L. The IC50 values for inhibition of ACh induced contraction for the stress and control group were 1.66×10-6 mol/L and 0.91×10-6mol/L, respectively. The ICs0 values for inhibition of KCl induced contraction for the stress and control group were 8.13×10-7 mol/L and 3.80×10-7 mol/L, respectively.CONCLUSION: Increase in [Ca2+]i of smooth muscle cells is directly related to the generation of contraction force in colon. L-type Ca2+ channels represent the main route of Ca2+ entry.Pinaverium inhibits the calcium influx through L-type channels;decreases the contractile response to many kinds of agonists and regulates the stress-induced colon hypermotility.
7. Tiotropium bromide in the routine care of GOLD stage II COPD patients: a pharmaeconomic evaluation
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Orietta Zaniolo
2011-06-01
Full Text Available Background: a secondary pre-specified analysis of the UPLIFT cohort demonstrated that the inclusion of tiotropium bromide in the routine care of GOLD stage II (moderate chronic obstructive pulmonary disease (COPD patients is associated with stronger improvements of survival, quality of life, and exacerbation rate than those shown in the total cohort; in this subgroup, tiotropium furthermore induces a significant reduction in the rate of FEV1 decline.Objective: to adapt the Spiriva® model, originally built to evaluate cost-effectiveness of tiotropium inclusion in the general COPD population, to GOLD II patients.Methods: the Spiriva® model is a probabilistic Markov patient-level simulation developed over a lifetime horizon to compare outcomes associated with the inclusion of tiotropium in routine care (RC for COPD treatment with those obtained with RC alone. Patients are characterised by gender, age, height, smoking status and FEV1. Model structure and sources have been maintained unvaried, except for demographic characteristics, specific for GOLD II patients, as extrapolated from an Italian observational study, and tiotropium efficacy, based on the secondary analysis of GOLD II UPLIFT patients. As in the original model, only direct health care costs are considered.Results: patients treated with tiotropium on average (95% CI gain 0.70 (0.00/7.23 LYs or 0.77 (0.02/4.67 QALYs compared to RC. The incremental lifetime cost is € 3,520 (-6,391/26,686, meaning that the incremental cost required to gain a QALY (incremental cost-effectiveness ratio – ICER is equal to € 4,548. Sensitivity analysis shows that tiotropium has a 50% probability of being cost-effective for a willingness-to-pay (WTP around 4,600 €/QALY; 100% probability is achieved with a WTP of € 9,300.Conclusions: the adoption of a strategy based on the inclusion of tiotropium from the early COPD stages represents good value for money in Italy, as the ICER estimated for GOLD II
8. COMPARISON OF ONSET TIME, DURATION OF ACTION AND INTUBATING CONDITION SACHIEVED WITH SUXAMETHONIUM AND ROCURONIUM BROMIDE
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Ajit P
2013-12-01
Full Text Available Adverse event profile ofSuxamethonium which is still the relaxant of choice to facilitate tracheal intubation inspired us to conduct a study in which we compared Onset time, Duration of Action and Intubating Conditions Achieved with Suxametho nium and Rocuronium Bromide with the Help of TOF Guard. AIMS : W e compared the onset of relaxation time, intubating condition, and duration of action, the cardiovascular effect, side effects between Suxamethonium and Rocuronium to ascertain the place of Rocu ronium as a relaxant for rapid sequence intubation as compared to the Suxamethonium. METHODS AND MATERIAL : The present study was carried out with the association of Department of Anesthesiology, S.S. Medical College and Associated S.G.M. and G.M. Hospitals, Rewa (M.P., and Departmen t of Pharmacology NSCB Medical C ollege Jabalpur (M.P. in 100 patients of either sex of ASA grade I and II between the ages of 16 to 70 years. The patients were randomly divided in two groups of 50 each. Group I & II received Sux amethonium 1.5 mg/kg B.W. or Rocuronium 1.0 mg/kg B.W. RESULTS : Onset time of maximum relaxation is < 60 seconds in each relaxants under study i.e. Rocuronium 1 mg/kg and Suxamethonium 1.5 mg/kg. Intubating conditions after Rocuronium 1 mg/kg are clinically acceptable in 100% of cases and are equivalent to that after Suxamethonium 1.5 mg/kg. Rocuronium upto dose of 1 mg/kg does not have any clinically significant cardiovascular effect. Rocuronium does not have any side effects including the sign of histamine release and anaphylactic or anaphylactoid reactions. Duration of action after Rocuronium 1 mg/kg is about 2346.4 seconds (39.14 minutes so it is not suitable for surgeries of short duration. CONCLUSIONS : Rocuronium can replace Suxamethonium for rapid sequ ence intubation in conditions where use of Suxamethonium is eithe r hazardous or contraindicated p rovided there is no anticipated difficulty in intubation.
9. Once-daily glycopyrronium bromide, a long-acting muscarinic antagonist, for chronic obstructive pulmonary disease: a systematic review of clinical benefit
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Ulrik CS
2012-09-01
Full Text Available Charlotte Suppli UlrikDepartment of Pulmonary Medicine, Hvidovre Hospital and University of Copenhagen, Copenhagen, DenmarkBackground: Long-acting bronchodilators are central in the pharmacological management of patients with chronic obstructive pulmonary disease (COPD. The aim of this systematic review is to provide an overview of the studies evaluating the safety and clinical efficacy of inhaled glycopyrronium bromide, a novel long-acting muscarinic antagonist, in patients with COPD.Methods: This study was performed as a systematic literature review.Results: Inhaled glycopyrronium bromide seems to be a safe and well tolerated long-acting muscarinic antagonist with a fast onset of action. In patients suffering from moderate to severe COPD, glycopyrronium bromide has clinically important effects on level of forced expiratory volume in one second, use of relief medication, percentage of days with no use of rescue medication, daytime dyspnea scores, and probably also on health status. Furthermore, in this group of patients, glycopyrronium bromide has beneficial effects on dynamic hyperinflation and exercise tolerance. Glycopyrronium bromide has been shown to reduce the rate of exacerbations in patients with moderate to severe COPD, but long-term controlled trials with exacerbation rate as the primary outcome variable have not been published yet.Conclusion: Once-daily inhaled glycopyrronium bromide has characteristics important for use in COPD, including a fast onset of action, sustained 24-hour bronchodilatation, and improvement in exercise tolerance, and therefore appears to have the potential for a significant role in the future management of COPD.Keywords: chronic obstructive pulmonary disease, glycopyrronium bromide, long-acting bronchodilators
10. CdTe quantum dots functionalized with 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide as luminescent nanoprobe for the sensitive recognition of bromide ion
Energy Technology Data Exchange (ETDEWEB)
Adegoke, Oluwasesan [Department of Chemistry, Rhodes University, Grahamstown 6140 (South Africa); Hosten, Eric; McCleland, Cedric [Department of Chemistry, Nelson Mandela Metropolitan University (South Campus), Port Elizabeth 6031 (South Africa); Nyokong, Tebello, E-mail: t.nyokong@ru.ac.za [Department of Chemistry, Rhodes University, Grahamstown 6140 (South Africa)
2012-04-06
Graphical abstract: A bromide ion-selective modified nanoprobe sensor based on 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4AT)-functionalized CdTe quantum dots (QDs-4AT) showed a high selectivity and sensitivity for the determination of bromide ion using fluorescence recovery. Highlights: Black-Right-Pointing-Pointer Water soluble CdTe quantum dots interact with tetramethylpiperidine-N-oxide. Black-Right-Pointing-Pointer Quantum dots fluorescence is quenched by the radical. Black-Right-Pointing-Pointer In the presence of bromide ions the fluorescence is restored. Black-Right-Pointing-Pointer The sensor is more selective to bromine ions than other common ions. - Abstract: A novel bromide ion-selective modified nanoprobe sensor based on 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4AT)-functionalized CdTe quantum dots (QDs-4AT) has been developed. Fluorescence quenching of the QDs by 4AT was observed. The functionalized QDs-4AT nanoprobe allowed a highly sensitive determination of bromide ion via analyte-induced change in the photoluminescence (fluorescence recovery) of the modified QDs. A detection limit of 0.6 nM of bromide ion was obtained, while the interfering effect of other inorganic cations and anions was investigated to examine the selectivity of the nanoprobe. The linear range was between 0.01 and 0.13 {mu}M. Combined fluorescence lifetime and electron paramagnetic resonance measurements confirmed electron transfer processes between bromide ion and QDs-4AT.
11. Titrimetric, spectrophotometric and kinetic methods for the assay of atenolol using bromate–bromide and methyl orange
Directory of Open Access Journals (Sweden)
KANAKAPURA BASAVAIAH
2006-05-01
Full Text Available Three new methods have been developed for the determination of atenolol in bulk drug and in tablet formulation. The methods are based on the oxidation–bromination reaction of the drug by bromine, generated in situ by the action of acid on a bromate–bromide mixture. In the titrimetric method, the drug is treated with a known excess of bromate–bromide mixture in hydrochloric acid medium, followed by the determination of the unreacted bromine iodometrically. The spectrophotometric method involves the addition of a measured excess of bromate–bromide reagent in hydrochloric acid medium to atenolol, and after ensuring the reaction had gone to completion, the unreacted bromine is treated with a fixed amount of methyl orange, and absorbance measured at 520 nm. The absorbance was found to increase linearly with increasing concentration of atenolol. The kinetic method depends on the existence of a linear relationship between the concentration of the drug and the time of the oxidation–bromination reaction, as indicated by the bleaching of methyl orange acid colour. The working conditions were optimized. The titrimetric method is based on a 1:1 reaction stoichiometry (atenolol:bromate and is applicable over the 3–20 mg range. The spectrophotometric method permits micro determination of the drug (0.5–4.0 mg ml-1with an apparentmolar absorptivity of 4.13x104 lmol-1 cm-1 and detection limit of 0.07 mg ml-1. The kinetic method is applicable in the concentration range 5–25 mg ml-1 with a detection limit of 3.72 mg ml-1. The proposed methods were successfully applied to the determination of atenolol in tablet preparations with mean recoveries of 97.63 to 101.78 %. The reliability of the assay was established by parallel determination by the reference method and by recovery studies using the standard addition technique.
12. Synthesis, characterization and thermal properties of new aromatic quaternary ammonium bromides: precursors for ionic liquids and complexation studies
Science.gov (United States)
Busi, Sara; Lahtinen, Manu; Ropponen, Jarmo; Valkonen, Jussi; Rissanen, Kari
2004-10-01
Series of new aromatic R2R‧2N+Br- (R=benzyl, 4-methylbenzyl, 2-phenylethyl, 3-phenylpropyl; R‧=ethyl, methyl, isopropyl) or RR‧2NH+Br--type (R=benzyl, R‧=isopropyl) quaternary ammonium bromides were prepared by using novel synthetic route in which a formamide (N,N-diethylformamide, N,N-dimethylformamide, N,N-diisopropylformamide) is treated with aralkyl halide in presence of a weak base. The compounds were characterized by 1H-NMR and 13C-NMR spectroscopy and mass spectrometry. Structures of the crystalline compounds were determined by X-ray single crystal diffraction, and in addition the powder diffraction method was used to study the structural similarities between the single crystal and microcrystalline bulk material. Three of the compounds crystallized in monoclinic, two in orthorhombic and one in triclinic crystal system, showing ion pairs, which are interconnected by weak hydrogen bonds and weak π - π interactions between the phenyl rings. Three of the compounds appeared as viscous oil or waxes. Finally, TG/DTA and DSC methods were used to analyze thermal properties of the prepared compounds. The lowest melting points were obtained for diethyldi-(2-phenylethyl)ammonium bromide (122.2 °C) and for diethyldi-(3-phenylpropyl)-ammonium bromide (109.1 °C). In general, decomposition of the compounds started at 170-190 °C without identifiable cleavages, thus liquid ranges of 30-70 °C were observed for some of the compounds.
13. A comparison of didodecyldimethylammonium bromide adsorbed at mica/water and silica/water interfaces using neutron reflection.
Science.gov (United States)
Griffin, Lucy R; Browning, Kathryn L; Truscott, Chris L; Clifton, Luke A; Webster, John; Clarke, Stuart M
2016-09-15
The layer structure of the dichain alkyl ammonium surfactant, didodecyldimethylammonium bromide (DDAB), adsorbed from water on to silica and mica surfaces has been determined using neutron reflection. Although sometimes considered interchangeable surfaces for study, we present evidence of significant differences in the adsorbed layer structure below the critical micelle concentration. A complete DDAB bilayer was assembled at the water/mica interface at concentrations below the critical micelle concentration (CMC). In contrast it is not until the CMC was reached that the complete bilayer structure formed on the oxidised silicon crystal. Removal of the complete bilayer on both surfaces was attempted by both washing and ion exchange yet the adsorbed structure proved tenacious.
14. Efficacy and safety of eco-friendly inhalers: focus on combination ipratropium bromide and albuterol in chronic obstructive pulmonary disease
Directory of Open Access Journals (Sweden)
Panos RJ
2013-04-01
Full Text Available Ralph J Panos1,2 1Pulmonary, Critical Care, and Sleep Medicine Division, Cincinnati Veterans Affairs Medical Center, 2Pulmonary, Critical Care, and Sleep Medicine Division, University of Cincinnati College of Medicine, Cincinnati, OH, USA Background: Chronic obstructive pulmonary disease (COPD is a major cause of morbidity and mortality and its treatment is critical to improve quality of life, reduce symptoms, and diminish the frequency of COPD exacerbations. Due to the harmful environmental effects of pressurized metered-dose inhalers (pMDIs containing chlorofluorocarbons (CFCs, newer systems for delivering respiratory medications have been developed. Methods: A search of the literature in the PubMed database was undertaken using the keywords “COPD,” “albuterol,” “ipratropium bromide,” and “Respimat® Soft Mist Inhaler™”; pertinent references within the identified citations were included. The environmental effect of CFC-pMDIs, the invention of the Respimat® Soft Mist Inhaler™ (SMI (Boehringer Ingelheim, Ingelheim, Germany, and its use to deliver the combination of albuterol and ipratropium bromide for the treatment of COPD were reviewed. Results: The adverse environmental effects of CFC-pMDIs stimulated the invention of novel delivery systems including the Respimat SMI. This review presents its development, internal mechanism, and use to deliver the combination of albuterol and ipratropium bromide. Conclusion: CFC-pMDIs contributed to the depletion of the ozone layer and the surge in disorders caused by harmful ultraviolet B radiation. The banning of CFCs spurred the development of novel delivery systems for respiratory medications. The Respimat SMI is an innovative device that produces a vapor of inhalable droplets with reduced velocity and prolonged aerosol duration that enhance deposition within the lower airway and is associated with improved patient satisfaction. Clinical trials have demonstrated that the Respimat SMI
15. Non-conservative behavior of bromide in surface waters and brines of Central Andes : a release into the atmosphere ?
OpenAIRE
Risacher, François; Fritz, B; Alonso, H.
2006-01-01
The transfer of reactive bromine into the atmosphere was recently observed by Honninger et al. [Honninger, G., Bobrowski, N., Palenque, E.R., Torrez, R., Platt, U., 2004. Reactive bromine and sulfur emission at salar de Uyuni, Bolivia. Geophys. Res. Lett. 31, doi:10.1029/2003GL018818] in a large salt pan of the Bolivian Altiplano: the salar de Uyuni. However, bromide is considered to be an excellent conservative tracer, which leads to the questioning of its actual conservation in surficial ge...
16. Investigating Two-Photon-Induced Fluorescence in Rhodamine-6G in Presence of Cetyl-Trimethyl-Ammonium-Bromide.
Science.gov (United States)
Maurya, Sandeep Kumar; Yadav, Dheerendra; Goswami, Debabrata
2016-09-01
We investigate the effect of cetyl-trimethyl-ammonium-bromides (CTAB) concentration on the fluorescence of Rhodamine-6G in water. This spectroscopic study of Rhodamine-6G in presence of CTAB was performed using two-photon-induced-fluorescence at 780 nm wavelength using high repetition rate femtosecond laser pulses. We report an increment of ∼10 % in the fluorescence in accordance with ∼12 % enhancement in the absorption intensity of the dye molecule around the critical micellar concentration. We discuss the possible mechanism for the enhancement in the two-photon fluorescence intensity and the importance of critical micellar concentration. PMID:27324955
17. The application of pancuronium bromide (Pavulon) forensic analyses to tissue samples from an "Angel of Death" investigation.
Science.gov (United States)
Andresen, Brian D; Alcaraz, Armando; Grant, Patrick M
2005-01-01
The case report of a serial killer who worked at several hospitals as a respiratory therapist is presented. The suspect was initially labeled a benevolent Angel of Death who ended the suffering of elderly patients through mercy killing. However, his subsequently declared motive for homicide was very different from other similar cases in medical settings. The application of new analysis techniques for the detection of pancuronium bromide in a series of aged exhumation tissues gave positive results and led to the resultant conviction of the therapist.
18. Solid-phase plate-reader quantification of specific PCR products by measurement of band-specific ethidium bromide fluorescence.
Science.gov (United States)
McCarthy, Michael T; O'Callaghan, Christopher A
2014-02-15
Real-time PCR is widely employed to quantify PCR products across a range of applications. However, accurate real-time PCR is not always technically feasible, and alternative methods for PCR product quantification can be expensive and time consuming to validate. We have developed an inexpensive, rapid, and immediately accessible protocol to quantify PCR products, by measuring ethidium bromide fluorescence of PCR products excised from agarose gels. This protocol has relevance to a broad range of methods in molecular biology where quantification of PCR products is necessary.
19. Motor effects of locally administered pinaverium bromide in the sigmoid tract of patients with irritable bowel syndrome.
Science.gov (United States)
Passaretti, S; Sorghi, M; Colombo, E; Mazzotti, G; Tittobello, A; Guslandi, M
1989-01-01
The effects of pinaverium bromide, a non-absorbable antispasmodic agent, administered locally, on sigmoid-rectal motility was investigated in 20 patients with irritable bowel syndrome. The influence of either pinaverium (10 subjects) or placebo (10 subjects) on a neostigmine-induced increase of sigmoid pressure was assessed and compared by means of computerized electromanometry. The drug was found to counteract significantly the motor effects of neostigmine, thus appearing to be an effective compound for the treatment of functional disorders of the colon. PMID:2744907
20. 1-Carboxymethyl-1′-carboxylatomethyl-3,3′-[p-phenylenebis(oxymethylene]dipyridinium bromide dihydrate
Directory of Open Access Journals (Sweden)
Wei-Cheng Pan
2010-10-01
Full Text Available In the crystal structure of the title salt, C22H21N2O6+·Br−·2H2O, pairs of betaine molecules are bridged by protons (the bridging proton is disordered, forming strong and symmetrical O—H...O hydrogen bonds, leading to an infinite chain along the b axis. The water molecules are linked to the betaine molecule and the bromide ion through O—H...O and O—H...Br interactions. The central ring, located on an inversion centre, makes dihedral angles of 1.2 (2° with the outer rings. One of the carboxylic acid groups is deprotonated.
1. Study of the Ion Channel Behavior of Didodecyldimethylammonium Bromide Formed Bilayer Lipid Membrane Stimulated by PF-6
Institute of Scientific and Technical Information of China (English)
TONG,Yue-Hong; HAN,Xiao-Jun; WANG,Er-Kang
2003-01-01
Bilayer lipid membranes ( BLM ) formed from didodecyldimethylammonium bromide were made on the freshly exposed surface ofa glassy carbon (GC) ani were demonstrated by the ac impedance spectroscopy. The ion channels of membrane properties induced by PF6- were studied by the cyclic voltammetric methods.Experimental results indicated that the ion channel of BLM was open in the presence of the PF6- due to the interaction of PF6- with the BLM, while it was switched offin the absence of PF6-. Because the ion channel behavior was affected by the concentration of PF6-,a sensor for PF6- can be developed.
2. Small angle neutron scattering studies of mixed micelles of sodium cumene sulphonate with cetyl trimethylammonium bromide and sodium dodecyl sulphate
K V Padalkar; V G Gaikar; V K Aswal
2008-11-01
The aqueous solutions of sodium cumene sulphonate (NaCS) and its mixtures with each of cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) are characterized by small angle neutron scattering (SANS). NaCS when added to CTAB solution leads to the formation of long rod-shaped micelles with a dramatic increase in the CTAB aggregation number. Its addition to SDS on the other hand results in the formation of smaller mixed micelles where part of SDS molecules in the micelle is replaced by NaCS molecules.
3. New air-stable planar chiral ferrocenyl monophosphine ligands: Suzuki cross-coupling of aryl chlorides and bromides
DEFF Research Database (Denmark)
Jensen, Jakob Feldthusen; Johannsen, Mogens
2003-01-01
GraphicA novel class of planar chiral electron-rich monophosphine ligands has been developed. The modular design allows a short and efficient synthesis of an array of aryl-ferrocenyl derivatives carrying the donating bis(dicyclohexyl)phosphino moiety. These new ligands have successfully been appl...... applied in the palladium-catalyzed Suzuki cross-coupling of activated as well as nonactivated aryl chlorides at room temperature. The asymmetric coupling of an aryl bromide and an aryl boronic acid was also tested, giving ees up to 54%....
4. 罗库溴铵合成路线图解%Graphical Synthetic Routes of Rocuronium Bromide
Institute of Scientific and Technical Information of China (English)
严慧; 邱飞; 刁勇
2011-01-01
@@ 罗库溴铵(rocuronium bromide,1),化学名为1-[(2β,3α,5α,16β,17β)-17-(乙酰氧基)-3-羟基-2-(4-吗啉基)雄甾烷-16-基]-1-(2-丙烯基)吡咯烷鎓溴化物,是荷兰Organon公司研发的一种非去极化甾醇类肌肉松弛药,1994年6月首次在美国上市.
5. Investigation of Surfactant-Stain-Metal Interaction: Naphthochrome Green/Cetyltrimethylammonium Bromide/Rare Earths Ternary Complexation
Institute of Scientific and Technical Information of China (English)
郑立新; 沈荣; 郜洪文
2003-01-01
The ternary interaction of naphthochrome green (NCG) with cetyltrimethylammonium bromide (CTAB) and rare earths (Res: Yb, Dy, Er and Eu) has been investigated with the microsurface adsorption-spectral correction technique (MSASC). The aggregation of NCG on CTAB obeys the Langmuir isothermal adsorption. The enrichment of NCG on CTAB and the presence of NaCl sensitize the complexation between Res and NCG. Both the binary aggregate and the ternary complex were characterized in the presence and absence of NaCl at pH 8.30 at 20 and 40℃.
6. Role of intravenously administered hyoscine butyl bromide in retrograde terminal ileoscopy: A randomized, double-blinded, placebo-controlled trial
Institute of Scientific and Technical Information of China (English)
SP Misra; M Dwivedi
2007-01-01
AIM:To evaluated the role of hyoscine butyl bromide in facilitating retrograde ileoscopy.METHODS:Retrograde terminal ileoscopy was attempted in 200 consecutive patients undergoing colonoscopy. After intubation of the cecum and visualization of the ileocecal valve,butyl bromide injection or normal saline was given intravenously to the patients in a double blind random fashion. The pulse rate and oxygen saturation were measured continuously. After completion of the procedure,endoscopists were then asked to score the ease of intubation and the ease of visualization of the terminal ileum on a visual scale of 1 to 10. The patients were also asked to score the pain after receiving hyoscine butyl bromide injection on a score of 1 to 10.RESULTS:Terminal ileoscopy could be performed in 188 patients. The mean (SD) visual analogue score for the ease of intubation of the cecum was 7.4 (0.65) in the injection group and 5.9 (0.8) in the placebo group (P＜0.001). The mean (SD) length of ileum visualized in the injection group was 14.4 (3.3) cm and 10.4 (2.7) cm in the placebo group (P＜0.001). The mean (SD) visual analogue score for ease of visualization of the terminal ileum was 7.5 (0.69) in the injection group and 5.9 (0.7) in the placebo group (P＜0.001). The pain score experienced by the patients was 6.5 (0.7) in the injection group and 6.7 (0.69) in the placebo group (P＜0.008). Although the pulse rate increased significantly in patients receiving the drug,no statistically significant difference was noted in the oxygen saturation between the two groups either before or after administration of the drug. No complications were observed in either of the groups.CONCLUSION:Hyoscine butyl bromide injection is a useful adjunct in helping the intubation and visualizationof terminal ileum during colonoscopy.
7. Americium behaviour in plastic vessels
Energy Technology Data Exchange (ETDEWEB)
Legarda, F.; Herranz, M. [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain); Idoeta, R., E-mail: raquel.idoeta@ehu.e [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain); Abelairas, A. [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain)
2010-07-15
The adsorption of {sup 241}Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of {sup 241}Am by these plastics was studied. The same was done by varying vessel agitation time, vessel agitation speed, surface/volume ratio of water in the vessels and water pH. Adsorptions were measured to be between 0% and 70%. The adsorption of {sup 241}Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification.
8. A sensitive and specific liquid chromatography/tandem mass spectrometry method for determination of pinaverium bromide in human plasma: application to a pharmacokinetic study in healthy volunteers.
Science.gov (United States)
Ren, Jin-Min; Zhao, Xi; Wang, Chuan-Ping; Sun, Qian; Yin, Li-Xin; Zhang, Zhi-Qing
2011-12-01
A sensitive and specific method using liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) for the determination of pinaverium bromide in human plasma was developed and validated. Pinaverium bromide and an internal standard (paclitaxel) were isolated from plasma samples by precipitating plasma, and determined by LC-MS/MS in multiple-reaction monitoring mode. The main metabolite of pinaverium bromide and endogenous substances in plasma did not show any interference. The calibration curve was linear over the plasma concentration range of 10.0-10000.0 pg/mL with a correlation coefficient of 0.9979. The relative standard derivations intra- and inter-day at 30.0, 300.0 and 8000.0 pg/mL in plasma were less than 15%. The absolute recoveries of pinaverium bromide and the internal standard were 99.7-111.7 and 106.2%, respectively. The lower limit of quantitation was 10 pg/mL. The analytical method was successfully applied to study the pharmacokinetics of pinaverium bromide tablets in healthy Chinese volunteers. PMID:21308709
9. Recent actions taken on methyl bromide under the Montreal Protocol: Their potential economic implications on international trade
International Nuclear Information System (INIS)
Methyl bromide (MB) produced and used by man is a versatile, highly effective, fastacting fumigant employed in a number of important ways to kill organisms destructive to plants. A wide spectrum of commodities is treated with MB. The compound is unique in that it provides a wide range of pest control, may be applied to a broad spectrum of both food and non-food commodities, can be used for fumigation of large and small quantities of materials, and, when applied properly, leaves no residues of toxicological significance. Recently, this compound has come under scientific scrutiny and has been identified as a potentially potent ozone depleting chemical. As a result, countries operating under the Montreal Protocol will be restricting its use, and, in some cases, eliminating its use altogether. To date there are no alternative chemical fumigants to replace methyl bromide. Non-chemical treatments such as irradiation, hot and cold treatments, modified atmosphere, etc., are the most promising. The paper focuses on the magnitude of the economic consequences on international trade and the necessity to have available alternative treatments that are highly effective, fast-acting, and practical. 8 refs, 12 tabs
10. Linear optical properties and their bond length dependence of yttrium bromide from ab initio and density functional theory calculations
Energy Technology Data Exchange (ETDEWEB)
Alipour, Mojtaba, E-mail: malipour@shirazu.ac.ir [Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Mohajeri, Afshan, E-mail: amohajeri@shirazu.ac.ir [Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)
2011-08-25
Graphical abstract: The electronic properties such as the static dipole polarizability, anisotropy of the polarizability, and dipole moment of yttrium bromide, YBr (X{sup 1}{Sigma}) have been theoretically studied. Highlights: {yields} Conventional ab initio and density functional theory methods were employed to study linear optical properties of YBr molecule. {yields} Properties derivatives and their level of theory dependence were studied. {yields} Electron correlation effects and rovibrational corrections have also been discussed. - Abstract: We have employed conventional ab initio and density functional theory methods to study the electronic properties such as the mean static dipole polarizability, {alpha}-bar, anisotropy of the polarizability, {Delta}{alpha}, and dipole moment, {mu}, of yttrium bromide. The bond length dependence of properties is determined at different levels of theory and appropriate expansions around experimental internuclear distance have been presented. Moreover, the first and second geometrical derivatives for each property are quantified and their level of theory dependence has been analyzed. To study the effect of molecular rotation and vibration on the electronic properties, the rovibrational corrections have also been carried out. It is found that these corrections are less pronounced for considered properties of YBr. In all calculations, the electron correlation effects have been considered and discussed. The obtained results show that the electron correlation is more significant in the calculation of the mean and the anisotropy of dipole polarizability.
11. Photoinduced Dissociation Of N-alkyl Bromides On Gallium Arsenide(110) And Gallium Arsenide(100) Electron And Fragment Dynamics
CERN Document Server
Khan, K A
1999-01-01
In this study we investigate the UV-initiated electron transfer and dissociation fragment dynamics of selected n-alkyl bromides physisorbed on single crystals of GaAs. By systematically varying different chemical and structural parameters of the adsorbate/substrate system we explore a number of fundamental questions regarding the basic physics and chemistry of photochemical processes on surfaces. Monolayers of methyl, ethyl and propyl bromide were deposited on the (110), Ga-terminated (100) and As- terminated (100) surfaces of GaAs without thermal decomposition at 80 K. Substrate-mediated electron transfer to the molecule, induced by exposure to UV light at 193, 248 and 351 nm, causes C-Br bond cleavage. The electron transfer dynamics of this mechanism are examined as a function of wavelength and molecular complexity of the adsorbate to better understand the flow of energy and charge across the adsorbate/substrate interface. The photodynamics of the alkyl fragments are studied using mass-, energy- and angle-r...
12. Study on the toxicity of sodium bromide to different fresh water organisms. [Scenedesmus pannonicus; Daphnia magna; Poecilia reticulata; Oryzias latipas
Energy Technology Data Exchange (ETDEWEB)
Canton, J.H.; Wester, P.W.; Mathijssen-Spiekman, E.A.
1983-08-01
The toxicity of sodium bromide for fresh water organisms was tested using algae (Scenedesmus pannonicus), crustaceans (Daphnia magna) and fish (Poecilia reticulata and Oryzias latipes). Depending on the species tested, the acute toxicity varied from 44 to 5800 mg Br-/litre (EC50 values) and the No Observed Effect Concentrations (NOEC values) in the long-term tests varied from 7.8 to 250 mg Br-/litre. Bromide ion markedly impaired reproduction in both crustaceans and fish. Histologically no effects were observed in the long-term test with Oryzias, but in the reproduction test with Poecilia, hyperplasia of the thyroid, atrophy and degeneration of the musculature and regressive changes in the female reproductive tract were observed. As a criterion of water quality, 1 mg Br-/litre has been proposed, on the basis of reproductive performance in the Poecilia test. The concentrations found in surface water frequently exceed this value and sometimes reach levels at which acute effects on water organisms can be expected.
13. The Efficacy and Safety of Topical Rocuronium Bromide to Induce Bilateral Mydriasis in Hispaniolan Amazon Parrots ( Amazona ventralis ).
Science.gov (United States)
Baine, Katherine; Hendrix, Diane V H; Kuhn, Sonia E; Souza, Marcy J; Jones, Michael P
2016-03-01
The efficacy and safety of topically applied rocuronium in Hispaniolan Amazon parrots ( Amazona ventralis ) was assessed in a group of 10 adult birds. A complete ophthalmic examination (including Schirmer tear test, ocular reflexes, applanation tonometry, fluorescein staining, and slit-lamp biomicroscopy) was performed, and rocuronium bromide (0.15 mg in both eyes) was administered. Pupillary light reflex (PLR) and pupillary diameter were recorded in a darkened room at the following time points: 0, 10, 20, 30, 40, 50, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 300, and 360 minutes, and 24 hours. Fluorescein staining in both eyes was performed at 24 hours. By 10 minutes, PLR was absent in all birds (at 5 minutes, 8 birds; at 10 minutes, remaining 2 birds). Pupil diameter differed significantly from baseline at all time points. Additionally, PLR was decreased in 7/10 birds at 360 minutes and normal in all birds at 24 hours. Superficial corneal ulceration was observed at 24 hours in the left eye of 2/10 of the birds after fluorescein stain application. This study demonstrated that rocuronium bromide was an effective mydriatic agent in Hispaniolan Amazon parrots with rapid onset and prolonged duration of action. PMID:27088739
14. The Efficacy and Safety of Topical Rocuronium Bromide to Induce Bilateral Mydriasis in Hispaniolan Amazon Parrots ( Amazona ventralis ).
Science.gov (United States)
Baine, Katherine; Hendrix, Diane V H; Kuhn, Sonia E; Souza, Marcy J; Jones, Michael P
2016-03-01
The efficacy and safety of topically applied rocuronium in Hispaniolan Amazon parrots ( Amazona ventralis ) was assessed in a group of 10 adult birds. A complete ophthalmic examination (including Schirmer tear test, ocular reflexes, applanation tonometry, fluorescein staining, and slit-lamp biomicroscopy) was performed, and rocuronium bromide (0.15 mg in both eyes) was administered. Pupillary light reflex (PLR) and pupillary diameter were recorded in a darkened room at the following time points: 0, 10, 20, 30, 40, 50, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 300, and 360 minutes, and 24 hours. Fluorescein staining in both eyes was performed at 24 hours. By 10 minutes, PLR was absent in all birds (at 5 minutes, 8 birds; at 10 minutes, remaining 2 birds). Pupil diameter differed significantly from baseline at all time points. Additionally, PLR was decreased in 7/10 birds at 360 minutes and normal in all birds at 24 hours. Superficial corneal ulceration was observed at 24 hours in the left eye of 2/10 of the birds after fluorescein stain application. This study demonstrated that rocuronium bromide was an effective mydriatic agent in Hispaniolan Amazon parrots with rapid onset and prolonged duration of action.
15. Sorption and transport studies of cetyl trimethylammonium bromide (CTAB)and Triton X-100 in clayey soil
Institute of Scientific and Technical Information of China (English)
Sivaram Harendra; Cumaraswamy Vipulanandan
2013-01-01
Surfactants are soil washing agents and facilitators for subsurface remediation of hydrocarbon spills.It is important to understand the sorption and transport behavior of surfactants for enhanced soil remediation.The adsorption and desorption isotherms of cetyl trimethylammonium bromide (CTAB) and Triton X-100 with sand and kaolinite have been quantified.Kaolinite clay had the highest sorption capacity compared to blasting sand.Transport parameters such as diffusion coefficient (D) and retardation factor (R) of the above mentioned surfactant solutions were determined in clayey soils (82.5％ sand and 17.5％ kaolinite mixture) with near zero and 0.1 g/L ionic strength.NaCl was used as the electrolyte solution.Convection-Diffusion equation was used to model the breakthrough curves of the surfactants.Bromide ion was chosen as the tracer material in order to characterize the column.CTAB and Triton X-100 were used to flush the perchloroethylene (PCE) contaminated soil.The effectiveness of CTAB and Triton X-100 in flushing the PCE from the contaminated soil was quantified.
16. High-performance liquid chromatographic assay for the simultaneous determination of ipratropium bromide, fenoterol, salbutamol and terbutaline in nebulizer solution.
Science.gov (United States)
Jacobson, G A; Peterson, G M
1994-06-01
A reversed-phase ion-pair high-performance liquid chromatography assay was developed for the simultaneous determination of ipratropium bromide, fenoterol hydrobromide, salbutamol sulphate and terbutaline sulphate in nebulizer solution. Chromatographic separation was achieved with a Nova-Pak C18 4 microns 10 cm x 8 mm i.d. Radial-pak cartridge inside a Waters RCM 8 x 10 compression module using ternary gradient analysis. Detection was performed using UV detection at 220 nm. The standard curves were linear over the following ranges: ipratropium bromide 20.8-250.0 micrograms ml-1, fenoterol hydrobromide 27.8-500.0 micrograms ml-1, salbutamol sulphate 34.7-2500.0 micrograms ml-1 and terbutaline sulphate 69.5-2500 micrograms ml-1. Inter-day and intra-day relative standard deviations for each compound ranged from 4.5-5.2% and 3.5-3.9%, respectively. The assay procedure was developed to allow the accurate determination of constituents in various combinations of nebulizer solution, as well as for stability indicating purposes. This provides a convenient means of testing long-term compatibility and stability following the post-manufacture mixing of commonly used nebulized preparations. PMID:7918785
17. Interaction between dodecyl oxypropyl β-hydroxyltrimethylammonium bromide and Xanthan: MesoDyn simulation and binding isotherm measurements
Institute of Scientific and Technical Information of China (English)
2007-01-01
MesoDyn density functional simulation method is used to study the interactions between dodecyl oxypropyl β-hydroxyltrimethylammonium bromide (C12NBr) and Xanthan (XC). The micro dynamic process of aggregate formation and the aggregate morphology are reported. Interaction between XC and nonyphenyloxypropylβ-hydroxyltrimethylammonium bromide (C9phNBr) is compared with that between XC and C12NBr. Simulation results show that the aggregate morphology of XC/C12NBr and XC/C9phNBr is of rod-like shape with helix characteristic. The binding of C9phNBr to XC is more difficult than that of C12NBr to XC. In addition, three stages for the dynamic evolution of surfactant binding to XC are observed. The simulation results agree with binding isotherms of C9phNBr (C12NBr) to XC obtained via the potentiometric titration method, which shows a typical cooperative binding between C9phNBr (C12NBr) and XC.
18. EURADOS action for determination of americium in skull measures in vivo and Monte Carlo simulation; Accion EURADOS para la determinacion de americio en craneo mediante medidas in-vivo y simulacion Monte Carlo
Energy Technology Data Exchange (ETDEWEB)
Lopez Ponte, M. A.; Navarro Amaro, J. F.; Perez Lopez, B.; Navarro Bravo, T.; Nogueira, P.; Vrba, T.
2013-07-01
From the Group of WG7 internal dosimetry of the EURADOS Organization (European Radiation Dosimetry group, e.V.) which It coordinates CIEMAT, international action for the vivo measurement of americium has been conducted in three mannequins type skull with detectors of Germanium by gamma spectrometry and simulation by Monte Carlo methods. Such action has been raised as two separate exercises, with the participation of institutions in Europe, America and Asia. Other actions similar precede this vivo intercomparison of measurement and modeling Monte Carlo1. The preliminary results and associated findings are presented in this work. The laboratory of the body radioactivity (CRC) of service counter of dosimetry staff internal (DPI) of the CIEMAT, it has been one of the participants in vivo measures exercise. On the other hand part, the Group of numerical dosimetry of CIEMAT is participant of the Monte Carlo2 simulation exercise. (Author)
19. Critical and shielding parametric studies with the Monte Carlo code TRIPOLI to identify the key points to take into account during the transportation of blanket assemblies with high ratio of americium
International Nuclear Information System (INIS) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7058293223381042, "perplexity": 11058.046398687593}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-22/segments/1495463607849.21/warc/CC-MAIN-20170524173007-20170524193007-00016.warc.gz"} |
https://eccc.weizmann.ac.il/author/02609/ | Under the auspices of the Computational Complexity Foundation (CCF)
REPORTS > AUTHORS > MAGNUS BORDEWICH:
All reports by Author Magnus Bordewich:
TR05-151 | 7th December 2005
Magnus Bordewich, Martin Dyer, Marek Karpinski
#### Metric Construction, Stopping Times and Path Coupling.
In this paper we examine the importance of the choice of metric in path coupling, and the relationship of this to \emph{stopping time analysis}. We give strong evidence that stopping time analysis is no more powerful than standard path coupling. In particular, we prove a stronger theorem for path coupling ... more >>>
TR05-002 | 6th January 2005
Magnus Bordewich, Martin Dyer, Marek Karpinski
#### Path Coupling Using Stopping Times and Counting Independent Sets and Colourings in Hypergraphs
We give a new method for analysing the mixing time of a Markov chain using
path coupling with stopping times. We apply this approach to two hypergraph
problems. We show that the Glauber dynamics for independent sets in a
hypergraph mixes rapidly as long as the maximum degree $\Delta$ of ... more >>>
ISSN 1433-8092 | Imprint | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9534139037132263, "perplexity": 2030.1675880854477}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-24/segments/1590347396495.25/warc/CC-MAIN-20200528030851-20200528060851-00507.warc.gz"} |
https://www.physicsforums.com/threads/finding-indexes.377824/ | # Finding indexes.
1. Feb 12, 2010
### The_Iceflash
I for the most part have this completed but I have a small question and thus checking if I did this correctly.
1. The problem statement, all variables and given/known data
Given the Sequence = $$\frac{n}{n+2}$$ $$\approx_{\epsilon}$$ 1 , for n >> 1
Show what index if $$\epsilon$$ = .001
" " if $$\epsilon$$ = .000002
" " for any $$\epsilon$$ > 0
2. Relevant equations
N/A
3. The attempt at a solution
for $$\epsilon$$ = .001 I did:
$$\left|\frac{n}{n+2}-1\right|< .001$$
$$\left|\frac{-2}{n+2}\right| < .001$$
$$\frac{2}{n+2} < .001$$
$$\frac{2}{n+2} < \frac{1}{1000}$$
$$\frac{n+2}{2} > 1000$$
$$n+2 > 2000$$
$$n > 1998$$
The only issue I have with this one and the next one is that they aren't decreasing and I'm not sure if it needs to be or not:
$$\frac{1999}{1999+2} = .9990004998$$
$$\frac{2000}{2000+2} = .9990009990$$
for $$\epsilon$$ = .000002 I did:
$$\left|\frac{n}{n+2}-1\right|< .000002$$
$$\left|\frac{-2}{n+2}\right| < .000002$$
$$\frac{2}{n+2} < .000002$$
$$\frac{2}{n+2} < \frac{2}{1000000}$$
$$\frac{n+2}{2} > \frac{1000000}{2}$$
$$n+2 > 1000000$$
$$n > 999998[tex] for any [tex]\epsilon$$ > 0
$$\left|\frac{n}{n+2}-1\right|< \epsilon$$
$$\left|\frac{-2}{n+2}\right| < \epsilon$$
$$\frac{2}{n+2} < \epsilon$$
$$\frac{n+2}{2} > \frac{1}{\epsilon}$$
$$n+2 > \frac{2}{\epsilon}$$
$$n > \frac{2}{\epsilon}-2$$
Last edited: Feb 12, 2010
2. Feb 12, 2010
### Staff: Mentor
Who are "they" in "they aren't decreasing"? The terms in the sequence n/(n + 2) are increasing, but you're looking at the difference n/(n + 2) - 1. This sequence is decreasing.
3. Feb 12, 2010
### The_Iceflash
The index:
I got n > 1998 as the index so,
$$\frac{1999}{1999+2} = .9990004998$$
$$\frac{2000}{2000+2} = .9990009990$$
4. Feb 12, 2010
### Staff: Mentor
This is to be expected in a sequence that is increasing, as {n/(n + 2)} is. A larger index gives you a larger value.
5. Feb 13, 2010
### HallsofIvy
As Mark44 said, that is to be expected. $\epsilon$ being smaller means you must get closer to the limit value which, in turn, means you must go further out in the sequence. As $\epsilon$ gets smaller, you should expect the index, N, to get larger, not smaller.
You may be thinking of function limits, $\lim_{x\to a}f(x)$ where to get closer to the limit, you must get closer to a: smaller $\epsilon$ means smaller $\delta$.
But with $\lim_{n\to \infty} a_n$ or even $\lim_{x\to\infty} f(x)$, your "a" is $\infty$ so you must get "closer to infinity" which means larger. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8612450361251831, "perplexity": 1122.6388610934673}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-13/segments/1521257646875.28/warc/CC-MAIN-20180319101207-20180319121207-00070.warc.gz"} |
https://huggingface.co/datasets/qa_srl | # Dataset: qa_srl
Languages: en
Multilinguality: monolingual
Size Categories: 10K<n<100K
Language Creators: expert-generated
Annotations Creators: expert-generated
Source Datasets: original
# Dataset Card for QA-SRL
### Dataset Summary
we model predicate-argument structure of a sentence with a set of question-answer pairs. our method allows practical large-scale annotation of training data. We focus on semantic rather than syntactic annotation, and introduce a scalable method for gathering data that allows both training and evaluation.
### Languages
This dataset is in english language.
## Dataset Structure
### Data Instances
We use question-answer pairs to model verbal predicate-argument structure. The questions start with wh-words (Who, What, Where, What, etc.) and contains a verb predicate in the sentence; the answers are phrases in the sentence. For example:
UCD finished the 2006 championship as Dublin champions , by beating St Vincents in the final .
Finished Who finished something?
Finished What did someone finish?
Finished What did someone finish something as?
Finished How did someone finish something?
beating Who beat someone?
beating When did someone beat someone?
beating Who did someone beat?
### Data Fields
Annotations provided are as follows:
• sentence: contains tokenized sentence
• sent_id: is the sentence identifier
• predicate_idx:the index of the predicate (its position in the sentence)
• predicate: the predicate token
• question: contains the question which is a list of tokens. The question always consists of seven slots, as defined in the paper. The empty slots are represented with a marker “_”. The question ends with question mark.
• answer: list of answers to the question
### Data Splits
Dataset Sentences Verbs QAs
newswire-train 744 2020 4904
newswire-dev 249 664 1606
newswire-test 248 652 1599
Wikipedia-train 1174 2647 6414
Wikipedia-dev 392 895 2183
Wikipedia-test 393 898 2201
Please note This dataset only has wikipedia data. Newswire dataset needs CoNLL-2009 English training data to get the complete data. This training data is under license. Thus, newswire dataset is not included in this data.
## Dataset Creation
### Source Data
#### Initial Data Collection and Normalization
We annotated over 3000 sentences (nearly 8,000 verbs) in total across two domains: newswire (PropBank) and Wikipedia.
### Annotations
#### Annotation process
non-expert annotators were given a short tutorial and a small set of sample annotations (about 10 sentences). Annotators were hired if they showed good understanding of English and the task. The entire screening process usually took less than 2 hours.
#### Who are the annotators?
10 part-time, non-exper annotators from Upwork (Previously oDesk)
## Considerations for Using the Data
Luheng He
### Citation Information
@InProceedings{huggingface:dataset,
title = {QA-SRL: Question-Answer Driven Semantic Role Labeling},
authors={Luheng He, Mike Lewis, Luke Zettlemoyer},
year={2015}
publisher = {cs.washington.edu},
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https://hal-normandie-univ.archives-ouvertes.fr/hal-02421547 | # Description of near-field digital in-line holography using vectorial Rayleigh-Sommerfeld integral
Abstract : We propose to simulate holograms with the vectorial Rayleigh-Sommerfeld diffraction integral. This new approach is compared with a classical Fresnel diffraction integral, and that is done through the comparison of the kernels. We define the limit where the Fresnel approximation fails to simulate holograms. We show that the vectorial Rayleigh-Sommerfeld diffraction integral is well adapted to simulate holograms in extremely near field conditions. This is particularly interesting when dealing with very small particles.
Document type :
Conference papers
Domain :
https://hal-normandie-univ.archives-ouvertes.fr/hal-02421547
Contributor : Alexandre Poux <>
Submitted on : Friday, December 20, 2019 - 3:17:01 PM
Last modification on : Tuesday, March 24, 2020 - 11:00:57 AM
### Citation
Teddy Tawk, Sébastien Coëtmellec, Denis Lebrun. Description of near-field digital in-line holography using vectorial Rayleigh-Sommerfeld integral. SPIE, 2018, Strasbourg, France. ⟨10.1117/12.2307493⟩. ⟨hal-02421547⟩
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https://mathematica.stackexchange.com/questions/174856/extracting-the-principal-component-analysis-vectors-in-the-original-basis | # Extracting the principal component analysis vectors in the original basis
I'm using Mathematica's PrincipalComponents[] to do a principal components analysis on a data set with m data points and n variables (m > n). The command produces the m by $n$ matrix which contains the representation of each of the data in the principal components basis.
My question is -- how can I instead extract the principal component vector itself, as coefficients of original variable basis vectors? I'm aware you can do this with singular value decomposition or calculating the eigenvectors of the covariance matrix, but in doing those calculations there is an arbitrary choice of sign involved which might not be the same choice as PrincipalComponents[]. I want to see exactly the principal component vectors used by PrincipalComponents[].
• I would say it's a duplicate of this: mathematica.stackexchange.com/q/37762/12 (though I'm not completely satisfied with that solution) – Szabolcs Jun 7 '18 at 18:37
• @Szabolcs Thanks for the link; the command FindGeometricTransform[] does seem to work. However it also seems very slow, without getting into details, I'm doing a principal components analysis on a set with ~20 observations and ~15 variables. PrincipalComponents[] is very fast. FindGeometricTransform[] takes minutes. If I remove half the variables it takes a few seconds. Frustrating since one would think PrincipalComponents[] would have already calculated them. – William Kennerly Jun 9 '18 at 4:31
• @Szabolcs I can update my previous comment to say that you can speed up FindGeometricTransform[] using the Method->"Linear" option, which the documentation says uses SVD just like PrincipalComponents[] should, so its speed is nearly instantaneous. Unfortunately I don't believe it orders the principal components by decreasing variance so this is still not the ideal solution. – William Kennerly Jun 9 '18 at 14:05
• I'm sorry, I don't have a good solution for you. When I needed this last time, I went straight to SingularValueDecomposition precisely because I couldn't get the transformation from PrincipalComponents. – Szabolcs Jun 9 '18 at 16:54
• I agree. I think it is worth contacting Wolfram Support about such issues and suggesting improvements for future versions. – Szabolcs Jun 13 '18 at 7:40 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6942166686058044, "perplexity": 755.663589250031}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-39/segments/1568514574662.80/warc/CC-MAIN-20190921190812-20190921212812-00152.warc.gz"} |
https://slideplayer.com/slide/1624990/ | # The Law of Cosines February 25, 2010.
## Presentation on theme: "The Law of Cosines February 25, 2010."— Presentation transcript:
The Law of Cosines February 25, 2010
Solving Oblique Triangles
Solving a triangle means finding the lengths of all the sides and the measures of all the angles. This problem requires that we know three of the sides or angles.
The Law of Sines We use the Law of Sines if we know:
Two angles and any side (AAS or ASA) One angle and two sides, where one of the sides is opposite the known angle (SSA)
Law of Cosines We use the Law of Cosines if we know:
One angle and its two adjacent sides (SAS) All three sides (SSS)
Questions What about AAA?
On page 612, why are there “Alternative Forms” of the Law of Cosines? Do we really need three equations for the Law of Cosines?
Homework Page 617, 1 – 7 (odd)
Download ppt "The Law of Cosines February 25, 2010."
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https://mathoverflow.net/questions/121315/projective-submanifolds-of-mathbb-cpn-whose-normals-bundles-are-sums-of-line/121321 | # Projective submanifolds of $\mathbb CP^n$ whose normals bundles are sums of linear.
Let $X\subset \mathbb CP^n$ be a smooth submanifold whose normal bundle is $$\bigoplus_{i=1}^{codim X}O(k_i).$$
Is there some general enough additional condition of $X$ that implies that $X$ is a complete intersection? For example, would $dimX\ge 2$ suffice (to exclude things like $X=\mathbb CP^1$)?
-
Perhaps this paper may answer your question: On the normal bundle of submanifolds of $\mathbb{P}^n$ by Lucian Badescu. Here is the link: arxiv.org/pdf/math/0701487.pdf – Mahdi Majidi-Zolbanin Feb 9 '13 at 20:25
Mahdi, thank you for the link to the paper! This is exactly what I wanted :). Would you like to make this comment an answer, so that I could accept it? – aglearner Feb 9 '13 at 21:06
## 3 Answers
I enter my comment as an answer. The paper On the normal bundle of submanifolds of $\mathbb{P}^n$ by Lucian Badescu contains some answers to the question. Here are the links:
Published version: http://www.ams.org/journals/proc/2008-136-05/S0002-9939-08-09255-1/
On arXiv version: http://arxiv.org/pdf/math/0701487v1.pdf
In particular, Theorem 1.2 (due to Faltings) in the above reference is of interest, in connection to this question.
-
If $X\subset\mathbb{P}^n$ is a smooth subvariety and the normal bundle splits then, by adjunction, $X$ is subcanonical i.e. $\omega_{X}\cong\mathcal{O}_X(k)$. This is important for the following result in codimension two.
In "Bénédicte Basili and Christian Peskine, Décomposition du fibré normal des surfaces lisses de $\mathbb{P}^4$ et structures doubles sur les solides de $\mathbb{P}^5$, Duke Math. J. Volume 69, Number 1 (1993), 1-245", you can find the following result:
Let $X\subset\mathbb{P}^N$, $n\geq 4$ be a smooth codimension two subvariety. If $N_X$ splits then $X$ is a complete intersection.
For curves in $\mathbb{P}^3$ is quite different and the following is still an open problem: "Let $C\subset\mathbb{P}^3$ be a smooth, connected curve. Is it true that if $N_C = \mathcal{O}_C(a)\oplus\mathcal{O}_C(b)$, then $C$ is a complete intersection?"
-
For sure if the variety is a complete intersection then the normal bundle splits. I am afraid that the other way round is not true. IMO it should imply just being locally complete intersection, and a priori there's no general condition that implies that a l.c.i. is a c.i., as far as I know
-
IMeasy, a smooth submanifold of $\mathbb CP^n$ is always a local complete intersection, is not it? On the other hand the condition that I impose is clearly strong, so I am still optimstic about a possible positive answer to the question :) – aglearner Feb 9 '13 at 18:19
Of course you are right. I am sorry I didn't notice that you assumed the smootheness of the variety. As it is now my comment means nothing. I will delete it in the next few days. ;) – IMeasy Feb 10 '13 at 13:02 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8841736912727356, "perplexity": 348.5042078169305}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-30/segments/1469257829970.64/warc/CC-MAIN-20160723071029-00284-ip-10-185-27-174.ec2.internal.warc.gz"} |
https://indico.math.cnrs.fr/event/3969/ | Séminaire de Mathématique
# On the deformation theory of discontinuous groups acting on solvable homogeneous spaces
## by Ali Baklouti (Faculty of Sciences of Sfax & IHES)
Europe/Paris
Amphithéâtre Léon Motchane (IHES)
### Amphithéâtre Léon Motchane
#### IHES
Le Bois Marie 35, route de Chartres 91440 Bures-sur-Yvette
Description
Let $G$ be a Lie group, $H$ a closed subgroup of $G$ and $\Gamma$ a discontinuous group for the homogeneous space $\mathscr{X}=G/H$, which means that $\Gamma$ is a discrete subgroup of $G$ acting properly discontinuously and fixed point freely on $\mathscr{X}$. The subject of the talk is to to deal with some questions related to the geometry of the parameter and the deformation spaces of the action of $\Gamma$ on $\mathscr{X}$, when the group $G$ is solvable. The local rigidity conjecture in the nilpotent case and the analogue of the Selberg-Weil-Kobayashi rigidity Theorem in such non-Riemannian setting is also discussed.
Organized by
Fanny Kassel
Contact
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https://huxorezyxa.carthage-publicite.com/fractional-sobolev-type-spaces-and-embeddings-book-1691kc.php | Last edited by Malakree
Tuesday, July 21, 2020 | History
2 edition of Fractional Sobolev-type spaces and embeddings found in the catalog.
Fractional Sobolev-type spaces and embeddings
JuМЃlio Severino Neves
# Fractional Sobolev-type spaces and embeddings
## by JuМЃlio Severino Neves
• 169 Want to read
• 30 Currently reading
Published .
Written in English
Edition Notes
D.Phil. 2001. BLDSC DXN041846.
ID Numbers Statement Júlio Severino Neves. Series Sussex theses ; S 5125 Open Library OL19706729M
Research Article Higher Order Sobolev-Type Spaces on the Real Line BogdanBojarski, 1 JuhaKinnunen, 2 andThomasZürcher 3,4 Institute of Mathematics, Polish Academy of Sciences, - Warsaw, Poland Department of Mathematics, School of Science and Technology, Aalto University, P.O. Box, Aalto, Finland. A distinguishing feature of the book is its focus on vector-valued Sobolev spaces. The final chapters include proofs of several landmark theorems, including Cheeger's stability theorem for Poincaré inequalities under Gromov–Hausdorff convergence, and the Keith–Zhong self-improvement theorem for Poincaré by:
Thanks for contributing an answer to Mathematics Stack Exchange! Please be sure to answer the question. Provide details and share your research! But avoid Asking for help, clarification, or responding to other answers. Making statements based on opinion; back them up with references or personal experience. Use MathJax to format equations. and for any p∈ [1,∞), we want to define the fractional Sobolev spaces Ws,p(Ω). In the literature, fractional Sobolev-type spaces are also called Aronszajn, Gagliardo or Slobodeckij spaces, by the name of the ones who introduced them, almost simul-taneously (see [3, 40, 79]). We start by fixing the fractional exponent sin (0,1).
Lectures on Isoperimetric and Isocapacitary Inequalities in the Theory of Sobolev Spaces Vladimir Maz’ya Abstract. Old and new author’s results on equivalence of various isoperimet-ric and isocapacitary inequalities, on one hand, and Sobolev’s type imbedding and compactness theorems, on the other hand, are described. It is proved thatFile Size: KB. We prove existence and uniqueness of mild solutions to Sobolev type fractional nonlocal dynamic equations in Banach spaces. The Sobolev nonlocal condition is considered in terms of a Riemann-Liouville fractional derivative. A Lagrange optimal control problem is considered, and existence of a multi-integral solution obtained.
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### Fractional Sobolev-type spaces and embeddings by JuМЃlio Severino Neves Download PDF EPUB FB2
Later, there have been more results for other Sobolevtype embeddings, namely for fractional Sobolev spaces, variable exponent Sobolev spaces, Besov and Triebel-Lizorkin spaces in R n. In mathematics, a Sobolev space is a vector space of functions equipped with a norm that is a combination of L p-norms of the function together with its derivatives up to a given order.
The derivatives are understood in a suitable weak sense to make the space complete, i.e. a Banach ively, a Sobolev space is a space of functions possessing sufficiently many. This paper deals with the fractional Sobolev spaces W s, p.
We analyze the relations among some of their possible definitions and their role in the trace theory. We prove continuous and compact embeddings, investigating the problem of the Cited by: s>0 and for any p∈ [1,∞), we want to define the fractional Sobolev spaces Ws,p(Ω).
In the literature, fractional Sobolev-type spaces are also called Aronszajn, Gagliardo or Slobodeckij spaces, by the name of the ones who introduced them, almost simultaneously (see [3, 44, 89]).
We start by fixing the fractional exponent s in (0,1). For Cited by: Sobolev embeddings in rearrangement-invariant Banach spaces Sobolev embeddings in r.i. spaces Kerman and Pick studied the Sobolev embeddings among r.i. spaces. In particular, they solved the following problems: Given an r.i. range space X(In), nd the largest r.i.
domain space, namely Z(In);satisfying W1Z(In),!X(In). We establish necessary and sufficient conditions for embeddings of Bessel potential spaces H σ X(IR n) with order of smoothness σ ∈ (0, n), modelled upon rearrangement invariant Banach function spaces X(IR n), into generalized Hölder spaces (involving k-modulus of smoothness).We apply our results to the case when X(IR n) is the Lorentz-Karamata space Cited by: B.
Opic Embeddings of Bessel potential and Sobolev type spaces, Colloquium del Departamento de Análisis Matemático, Sección 1, no. 48, Universidad Complutense de Madrid, CURSO –, – Google ScholarCited by: 2. A comprehensive approach to Sobolev type embeddings, involving arbitrary rearrangement-invariant norms on the entire Euclidean space ${\mathbb R^n}$, is offered.
In particular, the optimal target space in any such embedding is by: 7. Stack Exchange network consists of Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Visit Stack Exchange. Section 6 is devoted to the Sobolev embedding theorem and its improvement (like embeddings into Lorentz and Besov spaces). Section 7 concerns with interpolation properties of scales of Sobolev spaces.
Section 8 reflects some research interest of the authors. We deal with non-classical anisotropic Sobolev spaces. naturally appear, as well as analogous Bessel potential spaces H. Of course, one also needs Sobolev type embeddings. By localization and local charts, we reduce these results to the model cases of full- and half-spaces.
There we use that the related H spaces are the do-mains of the operator L= (1 @ t) + (1) =2 having bounded imaginary powers, see.
Hitchhiker’s guide to the fractional Sobolev spaces Sobolev inequalities and continuous embeddings are dealt with in Section 6, while Section 7 is devoted to compact embeddings. fractional Sobolev-type spaces are also called Aronszajn, Gagliardo or Slobodeckij spaces. Hitchhiker’s guide to the fractional Sobolev spaces Eleonora Di Nezzaa, Giampiero Palatuccia,b,1, is a very evenly edited book and contains many passages that simply fractional Sobolev-type spaces are also called Aronszajn, Gagliardo or Slobodeckij spaces, by the name of the ones.
The Sobolev type embedding for negative Sobolev space. Ask Question Asked 4 years, 11 months ago. Thanks for contributing an answer to Mathematics Stack Exchange. Browse other questions tagged sobolev-spaces or ask your own question.
We study weighted Sobolev embeddings in radially symmetric function spaces and then investigate the existence of nontrivial radial solutions of inhomogeneous quasilinear elliptic equation with singular potentials and super-$(p, q)$-linear by: 6.
FOCK-SOBOLEV SPACES OF FRACTIONAL ORDER HONG RAE CHO, BOO RIM CHOE, AND HYUNGWOON KOO the full range of index 0. Fractional Sobolev spaces 7 Embedding properties This subsection is devoted to the embeddings of fractional Sobolev spaces into Lebesgue spaces.
We point out that Sobolev inequalities and continuous (compact) embeddings of the spaces Ws,p into the classical Lebesgue spaces Lq are exhaustively treated in [83, sections 6 and 7] (see. Sobolev spaces in mathematics I: Sobolev type inequalities Vladimir Maz'ya This volume is dedicated to the centenary of the outstanding mathematician of the 20th century, Sergey Sobolev, and, in a sense, to his celebrated work On a theorem of functional analysis, published inexactly 70 years ago, was where the original Sobolev inequality.
on the fractional Sobolev spaces Ws,p. Mathematics Subject Classification. Primary 46E35; Secondary 35S30, 35S Key words and phrases. Fractional Sobolev spaces, Gagliardo norm, fractional Laplacian, non-local energy, Sobolev embeddings, Riesz potential.
GP has been supported by Istituto Nazionale di Alta Matematica “F. Severi” (Indam). LITTLEWOOD-PALEY CHARACTERIZATIONS OF ANISOTROPIC HARDY SPACES OF MUSIELAK-ORLICZ TYPE Li, Baode, Fan, Xingya, and Yang, Dachun, Taiwanese Journal of Mathematics, ; Limiting cases of Sobolev inequalities on stratified groups Ruzhansky, Michael and Yessirkegenov, Nurgissa, Proceedings of the Japan Academy, Series A.
On the Bourgain, Brezis, and Mironescu theorem concerning limiting embeddings of fractional Sobolev spaces V. Maz’ya, T. Shaposhnikova Abstract The article is concerned with the Bourgain, Brezis and Mironescu theorem on the asymptotic behaviour of the norm of the Sobolev type embedding operator: Ws;p!Lpn=(n¡sp) as s"1 and s"n=p.
Their result.WEIGHTED SOBOLEV-TYPE EMBEDDING THEOREMS FOR FUNCTIONS WITH SYMMETRIES S. V. IVANOV AND A. I. NAZAROV Abstract. It is well known that Sobolev embeddings can be refined in the presence of symmetries. Hebey and Vaugon () studied this phenomena in the context of an arbitrary Riemannian manifold M and a compact group of .embeddings, SIAM J.
Numer. Anal. 54 (), { T. Kuhn and M. Petersen, Approximation in periodic Gevrey spaces, in progress Thomas Kuhn (Leipzig) Approximation of Sobolev embeddings C aceres 3 / | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6664738059043884, "perplexity": 2555.7765548002203}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178383355.93/warc/CC-MAIN-20210308082315-20210308112315-00140.warc.gz"} |
http://www.walkingrandomly.com/?cat=42 | ## Faster transpose matrix multiplication in R
May 23rd, 2017
I’m working on optimising some R code written by a researcher at University of Sheffield and its very much a war of attrition! There’s no easily optimisable hotspot and there’s no obvious way to leverage parallelism. Progress is being made by steadily identifying places here and there where we can do a little better. 10% here and 20% there can eventually add up to something worth shouting about.
One such micro-optimisation we discovered involved multiplying two matrices together where one of them needed to be transposed. Here’s a minimal example.
#Set random seed for reproducibility
set.seed(3)
# Generate two random n by n matrices
n = 10
a = matrix(runif(n*n,0,1),n,n)
b = matrix(runif(n*n,0,1),n,n)
# Multiply the matrix a by the transpose of b
c = a %*% t(b)
When the speed of linear algebra computations are an issue in R, it makes sense to use a version that is linked to a fast implementation of BLAS and LAPACK and we are already doing that on our HPC system.
Here, I am using version 3.3.3 of Microsoft R Open which links to Intel’s MKL (an implementation of BLAS and LAPACK) on a Windows laptop.
In R, there is another way to do the computation c = a %*% t(b) — we can make use of the tcrossprod function (There is also a crossprod function for when you want to do t(a) %*% b)
c_new = tcrossprod(a,b)
Let’s check for equality
c_new == c
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[2,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[3,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[4,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[5,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[6,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[7,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[8,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[9,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
[10,] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
Sometimes, when comparing the two methods you may find that some of those entries are FALSE which may worry you!
If that happens, computing the difference between the two results should convince you that all is OK and that the differences are just because of numerical noise. This happens sometimes when dealing with floating point arithmetic (For example, see http://www.walkingrandomly.com/?p=5380).
Let’s time the two methods using the microbenchmark package.
install.packages('microbenchmark')
library(microbenchmark)
We time just the matrix multiplication part of the code above:
microbenchmark(
original = a %*% t(b),
tcrossprod = tcrossprod(a,b)
)
Unit: nanoseconds
expr min lq mean median uq max neval
original 2918 3283 3491.312 3283 3647 18599 1000
tcrossprod 365 730 756.278 730 730 10576 1000
We are only saving microseconds here but that’s more than a factor of 4 speed-up in this small matrix case. If that computation is being performed a lot in a tight loop (and for our real application, it was), it can add up to quite a difference.
As the matrices get bigger, the speed-benefit in percentage terms gets lower but tcrossprod always seems to be the faster method. For example, here are the results for 1000 x 1000 matrices
#Set random seed for reproducibility
set.seed(3)
# Generate two random n by n matrices
n = 1000
a = matrix(runif(n*n,0,1),n,n)
b = matrix(runif(n*n,0,1),n,n)
microbenchmark(
original = a %*% t(b),
tcrossprod = tcrossprod(a,b)
)
Unit: milliseconds
expr min lq mean median uq max neval
original 18.93015 26.65027 31.55521 29.17599 31.90593 71.95318 100
tcrossprod 13.27372 18.76386 24.12531 21.68015 23.71739 61.65373 100
The cost of not using an optimised version of BLAS and LAPACK
While writing this blog post, I accidentally used the CRAN version of R. The recently released version 3.4. Unlike Microsoft R Open, this is not linked to the Intel MKL and so matrix multiplication is rather slower.
For our original 10 x 10 matrix example we have:
library(microbenchmark)
#Set random seed for reproducibility
set.seed(3)
# Generate two random n by n matrices
n = 10
a = matrix(runif(n*n,0,1),n,n)
b = matrix(runif(n*n,0,1),n,n)
microbenchmark(
original = a %*% t(b),
tcrossprod = tcrossprod(a,b)
)
Unit: microseconds
expr min lq mean median uq max neval
original 3.647 3.648 4.22727 4.012 4.1945 22.611 100
tcrossprod 1.094 1.459 1.52494 1.459 1.4600 3.282 100
Everything is a little slower as you might expect and the conclusion of this article — tcrossprod(a,b) is faster than a %*% t(b) — seems to still be valid.
However, when we move to 1000 x 1000 matrices, this changes
library(microbenchmark)
#Set random seed for reproducibility
set.seed(3)
# Generate two random n by n matrices
n = 1000
a = matrix(runif(n*n,0,1),n,n)
b = matrix(runif(n*n,0,1),n,n)
microbenchmark(
original = a %*% t(b),
tcrossprod = tcrossprod(a,b)
)
Unit: milliseconds
expr min lq mean median uq max neval
original 546.6008 587.1680 634.7154 602.6745 658.2387 957.5995 100
tcrossprod 560.4784 614.9787 658.3069 634.7664 685.8005 1013.2289 100
As expected, both results are much slower than when using the Intel MKL-lined version of R (~600 milliseconds vs ~31 milliseconds) — nothing new there. More disappointingly, however, is that now tcrossprod is slightly slower than explicitly taking the transpose.
As such, this particular micro-optimisation might not be as effective as we might like for all versions of R.
## Reproducible research in Ecology
September 5th, 2016
One of the great things about being a Research Software Engineer is the diversity of work you can get involved with. I specialise in smaller interventions which means that I can be working with physicists on Monday, engineers on Tuesday, geneticists on Wednesday….you get the idea.
Last month, I got to work with some Ecologists along with Anna Krystalli. We undertook the arduous journey from Sheffield down to Exeter to deliver talks and workshops at a post-conference symposium on reproducibility in science, organised by Malika Ihle and Isabel Winney, at the International Symposium on Behavioural Ecology.
I gave my talk, Is your research software correct?, and also delivered a workshop on using projects and version control using R and RStudio in the Code Cafe style. For the full write up of the day, see the excellent blog post by Anna over at the Mozilla Science Lab blog.
## How to enable the Linux / Bash subsystem in Windows 10
August 5th, 2016
Like many people, I was excited to learn about the new Linux subsystem in Windows announced by Microsoft earlier this year (See Bash on Windows: The scripting game just changed).
Along with others, I’ve been playing with it on the Windows Insider builds but now that the Windows Anniversary Update has been released, everyone can get in on the action.
Activating the Linux Subsystem in Windows
Once you’ve updated to the Anniversary Update of Windows, here’s what you need to do.
Open settings
In settings, click on Update and Security
In Update and Security, click on For developers in the left hand pane. Then click on Developer mode.
Take note of the Use developer features warning and click Yes if you are happy. Developer mode gives you greater power, and with great power comes great responsibility.
Reboot the machine (may not be necessary here but it’s what I did).
Search for Features and click on Turn Windows features on or off
Tick Windows Subsystem for Linux (Beta) and click OK
When it’s finished churning, reboot the machine.
Launch cmd.exe
Type bash, press enter and follow the instructions
Try something linux-y
The short version of what’s available is ‘Every userland tool that’s available for Ubuntu’ with the caveat that anything requiring a GUI won’t work.
This isn’t emulation, it isn’t cygwin, it’s something else entirely. It’s very cool!
The gcc compiler isn’t installed by default so let’s fix that:
sudo apt-get install gcc
Using your favourite terminal based editor (I used vi), enter the following ‘Hello World’ code in C and call it hello.c.
/* Hello World program */
#include
int main()
{
printf("Hello World from C\n");
return(0);
}
Compile using gcc
gcc hello.c -o hello
Run the executable
./hello
Hello World from C
Now, transfer the executable to a modern Ubuntu machine (I just emailed it to myself) and run it there.
That’s right – you just wrote and compiled a C-program on a Windows machine and ran it on a Linux machine.
Now install cowsay — because you can:
sudo apt-get install cowsay
cowsay 'Hello from Windows'
____________________
< Hello from Windows >
--------------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
Update 1:
I was challenged by @linuxlizard to do a follow up tutorial that showed how to install the scientific Python stack — Numpy, SciPy etc.
It’s all there :)
sudo apt-get install python-scipy
Update 2
TensorFlow on LinuxOnWindows is also easy: http://www.hanselman.com/blog/PlayingWithTensorFlowOnWindows.aspx
## Interactive explorations with Maple: An introduction to the Explore function using the power series for sin(x)
July 13th, 2015
It is possible to write quick, interactive demonstrations in a variety of languages these days. Functions such as Mathematica’s Manipulate, Sage Math’s interact and IPython’s interact allow programmers to write functional graphical user interfaces with just a few lines of code.
Earlier this week, I hosted a session in the Faculty of Engineering at The University of Sheffield where Maplesoft showed us, among other things, their version of this technology. This blog post is an extension of my notes from this part of the session.
The series command expands a function as a power series around a point. For example, let’s expand sin(x) as a power series around the point x=0.
series(sin(x), x = 0, 10)
If we try to plot this, we get an error message
plot(series(sin(x), x = 0, 10), x = -2*Pi .. 2*Pi, y = -3 .. 3)
Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct
This is because the output of the series command is a series data structure — something that the plot function cannot handle. We can, however, convert this to a polynomial which is something that the plot function can handle
convert(series(sin(x), x = 0, 10), polynom)
Wrapping the above with plot gives:
plot(convert(series(sin(x), x = 0, 10), polynom), x = -2*Pi .. 2*Pi, y = -3 .. 3);
Let’s see how close this is to the sin(x) curve by plotting them both together
plot([sin(x), convert(series(sin(x), x = 0, 10), polynom)], x = -2*Pi .. 2*Pi, y = -3 .. 3);
It would be nice if we could see how the approximation varies as we vary the number of terms in the expansion. Change the value 10 to a parameter a, pass the whole thing to the Explore function and we get an interactive widget.
Explore(plot([sin(x), convert(series(sin(x), x = 0, a), polynom)], x = -2*Pi .. 2*Pi, y = -3 .. 3), parameters = [a = 2 .. 20]);
Here’s a screenshot of it:
It would also be nice to vary the point we expand around. Change the value 0 to b and add an extra parameter to Explore to get two sliders instead of one:
Explore(plot([sin(x), convert(series(sin(x), x = b, a), polynom)], x = -2*Pi .. 2*Pi, y = -3 .. 3), parameters = [a = 2 .. 20, b = -2*Pi .. 2*Pi]);
To see what this looks like, open the companion worksheet in Maple.
We can change the labels on the sliders as follows
Explore(plot([sin(x), convert(series(sin(x), x = b, a), polynom)], x = -2*Pi .. 2*Pi, y = -3 .. 3), parameters = [[a = 2 .. 20, label = Number Of Terms], [b = -2*Pi .. 2*Pi, label = Expansion location]]);
To see what this looks like, open the companion worksheet in Maple.
Finally, let’s set some starting values for each slider
Explore(plot([sin(x), convert(series(sin(x), x = b, a), polynom)], x = -2*Pi .. 2*Pi, y = -3 .. 3), parameters = [[a = 2 .. 20, label = Number Of Terms], [b = -2*Pi .. 2*Pi, label = Expansion location]], initialvalues = [a = 2, b = 1]);
The resulting interactive widget looks like this:
Not bad for one line of code!
At The University of Sheffield, we are lucky because all of our staff and students have access to Maple on both university-owned and personally-owned equipment. If your audience isn’t as fortunate, they can access the resulting worksheet on the Maple Cloud.
## Interactive ‘Mystery Curve’ using Jupyter notebook
June 4th, 2015
The ever-superb John D. Cook recently found this lovely looking curve in a book he’s currently reading
John posted some Python code that reproduced this curve. I stole borrowed his code, put it in a Jupyter notebook and wrapped it in an interactive widget to allow me to play with the parameters and see what other curves I could come up with. The result looks like this.
If you’d like something where those sliders work, you need to run the notebook I’ve created in Project Jupyter. Here are 2 ways to do that.
Once you have the notebook open, click on Cell->Run All and play with the sliders that pop up.
## Checkpointing MATLAB Programs
February 19th, 2014
I occasionally get emails from researchers saying something like this
‘My MATLAB code takes a week to run and the cleaner/cat/my husband keeps switching off my machine before it’s completed — could you help me make the code go faster please so that I can get my results in between these events’
While I am more than happy to try to optimise the code in question, what these users really need is some sort of checkpointing scheme. Checkpointing is also important for users of high performance computing systems that limit the length of each individual job.
The solution – Checkpointing (or ‘Assume that your job will frequently be killed’)
The basic idea behind checkpointing is to periodically save your program’s state so that, if it is interrupted, it can start again where it left off rather than from the beginning. In order to demonstrate some of the principals involved, I’m going to need some code that’s sufficiently simple that it doesn’t cloud what I want to discuss. Let’s add up some numbers using a for-loop.
%addup.m
%This is not the recommended way to sum integers in MATLAB -- we only use it here to keep things simple
%This version does NOT use checkpointing
mysum=0;
for count=1:100
mysum = mysum + count;
pause(1); %Let's pretend that this is a complicated calculation
fprintf('Completed iteration %d \n',count);
end
fprintf('The sum is %f \n',mysum);
Using a for-loop to perform an addition like this is something that I’d never usually suggest in MATLAB but I’m using it here because it is so simple that it won’t get in the way of understanding the checkpointing code.
If you run this program in MATLAB, it will take about 100 seconds thanks to that pause statement which is acting as a proxy for some real work. Try interrupting it by pressing CTRL-C and then restart it. As you might expect, it will always start from the beginning:
>> addup
Completed iteration 1
Completed iteration 2
Completed iteration 3
Operation terminated by user during addup (line 6)
Completed iteration 1
Completed iteration 2
Completed iteration 3
Operation terminated by user during addup (line 6)
This is no big deal when your calculation only takes 100 seconds but is going to be a major problem when the calculation represented by that pause statement becomes something like an hour rather than a second.
Let’s now look at a version of the above that makes use of checkpointing.
%addup_checkpoint.m
if exist( 'checkpoint.mat','file' ) % If a checkpoint file exists, load it
else %otherwise, start from the beginning
fprintf('No checkpoint file found - starting from beginning\n');
mysum=0;
countmin=1;
end
for count = countmin:100
mysum = mysum + count;
pause(1); %Let's pretend that this is a complicated calculation
%save checkpoint
countmin = count+1; %If we load this checkpoint, we want to start on the next iteration
fprintf('Saving checkpoint\n');
save('checkpoint.mat');
fprintf('Completed iteration %d \n',count);
end
fprintf('The sum is %f \n',mysum);
Before you run the above code, the checkpoint file checkpoint.mat does not exist and so the calculation starts from the beginning. After every iteration, a checkpoint file is created which contains every variable in the MATLAB workspace. If the program is restarted, it will find the checkpoint file and continue where it left off. Our code now deals with interruptions a lot more gracefully.
>> addup_checkpoint
No checkpoint file found - starting from beginning
Saving checkpoint
Completed iteration 1
Saving checkpoint
Completed iteration 2
Saving checkpoint
Completed iteration 3
Operation terminated by user during addup_checkpoint (line 16)
Saving checkpoint
Completed iteration 4
Saving checkpoint
Completed iteration 5
Saving checkpoint
Completed iteration 6
Operation terminated by user during addup_checkpoint (line 16)
Note that we’ve had to change the program logic slightly. Our original loop counter was
for count = 1:100
In the check-pointed example, however, we’ve had to introduce the variable countmin
for count = countmin:100
This allows us to start the loop from whatever value of countmin was in our last checkpoint file. Such minor modifications are often necessary when converting code to use checkpointing and you should carefully check that the introduction of checkpointing does not introduce bugs in your code.
Don’t checkpoint too often
The creation of even a small checkpoint file is a time consuming process. Consider our original addup code but without the pause command.
%addup_nopause.m
%This version does NOT use checkpointing
mysum=0;
for count=1:100
mysum = mysum + count;
fprintf('Completed iteration %d \n',count);
end
fprintf('The sum is %f \n',mysum);
On my machine, this code takes 0.0046 seconds to execute. Compare this to the checkpointed version, again with the pause statement removed.
%addup_checkpoint_nopause.m
if exist( 'checkpoint.mat','file' ) % If a checkpoint file exists, load it
else %otherwise, start from the beginning
fprintf('No checkpoint file found - starting from beginning\n');
mysum=0;
countmin=1;
end
for count = countmin:100
mysum = mysum + count;
%save checkpoint
countmin = count+1; %If we load this checkpoint, we want to start on the next iteration
fprintf('Saving checkpoint\n');
save('checkpoint.mat');
fprintf('Completed iteration %d \n',count);
end
fprintf('The sum is %f \n',mysum);
This checkpointed version takes 0.85 seconds to execute on the same machine — Over 180 times slower than the original! The problem is that the time it takes to checkpoint is long compared to the calculation time.
If we make a modification so that we only checkpoint every 25 iterations, code execution time comes down to 0.05 seconds:
%Checkpoint every 25 iterations
if exist( 'checkpoint.mat','file' ) % If a checkpoint file exists, load it
else %otherwise, start from the beginning
fprintf('No checkpoint file found - starting from beginning\n');
mysum=0;
countmin=1;
end
for count = countmin:100
mysum = mysum + count;
countmin = count+1; %If we load this checkpoint, we want to start on the next iteration
if mod(count,25)==0
%save checkpoint
fprintf('Saving checkpoint\n');
save('checkpoint.mat');
end
fprintf('Completed iteration %d \n',count);
end
fprintf('The sum is %f \n',mysum);
Of course, the issue now is that we might lose more work if our program is interrupted between checkpoints. Additionally, in this particular case, the mod command used to decide whether or not to checkpoint is more expensive than simply performing the calculation but hopefully that isn’t going to be the case when working with real world calculations.
In practice, we have to work out a balance such that we checkpoint often enough so that we don’t stand to lose too much work but not so often that our program runs too slowly.
Checkpointing code that involves random numbers
Extra care needs to be taken when running code that involves random numbers. Consider a modification of our checkpointed adding program that creates a sum of random numbers.
%addup_checkpoint_rand.m
%Adding random numbers the slow way, in order to demo checkpointing
%This version has a bug
if exist( 'checkpoint.mat','file' ) % If a checkpoint file exists, load it
else %otherwise, start from the beginning
fprintf('No checkpoint file found - starting from beginning\n');
mysum=0;
countmin=1;
rng(0); %Seed the random number generator for reproducible results
end
for count = countmin:100
mysum = mysum + rand();
countmin = count+1; %If we load this checkpoint, we want to start on the next iteration
pause(1); %pretend this is a complicated calculation
%save checkpoint
fprintf('Saving checkpoint\n');
save('checkpoint.mat');
fprintf('Completed iteration %d \n',count);
end
fprintf('The sum is %f \n',mysum);
In the above, we set the seed of the random number generator to 0 at the beginning of the calculation. This ensures that we always get the same set of random numbers and allows us to get reproducible results. As such, the sum should always come out to be 52.799447 to the number of decimal places used in the program.
The above code has a subtle bug that you won’t find if your testing is confined to interrupting using CTRL-C and then restarting in an interactive session of MATLAB. Proceed that way, and you’ll get exactly the sum you’ll expect : 52.799447. If, on the other hand, you test your code by doing the following
• Run for a few iterations
• Interrupt with CTRL-C
• Restart MATLAB
• Run the code again, ensuring that it starts from the checkpoint
You’ll get a different result. This is not what we want!
The root cause of this problem is that we are not saving the state of the random number generator in our checkpoint file. Thus, when we restart MATLAB, all information concerning this state is lost. If we don’t restart MATLAB between interruptions, the state of the random number generator is safely tucked away behind the scenes.
Assume, for example, that you stop the calculation running after the third iteration. The random numbers you’d have consumed would be (to 4 d.p.)
0.8147
0.9058
0.1270
Your checkpoint file will contain the variables mysum, count and countmin but will contain nothing about the state of the random number generator. In English, this state is something like ‘The next random number will be the 4th one in the sequence defined by a starting seed of 0.’
When we restart MATLAB, the default seed is 0 so we’ll be using the right sequence (since we explicitly set it to be 0 in our code) but we’ll be starting right from the beginning again. That is, the 4th,5th and 6th iterations of the summation will contain the first 3 numbers in the stream, thus double counting them, and so our checkpointing procedure will alter the results of the calculation.
In order to fix this, we need to additionally save the state of the random number generator when we save a checkpoint and also make correct use of this on restarting. Here’s the code
%addup_checkpoint_rand_correct.m
%Adding random numbers the slow way, in order to demo checkpointing
if exist( 'checkpoint.mat','file' ) % If a checkpoint file exists, load it
%use the saved RNG state
stream = RandStream.getGlobalStream;
stream.State = savedState;
else % otherwise, start from the beginning
fprintf('No checkpoint file found - starting from beginning\n');
mysum=0;
countmin=1;
rng(0); %Seed the random number generator for reproducible results
end
for count = countmin:100
mysum = mysum + rand();
countmin = count+1; %If we load this checkpoint, we want to start on the next iteration
pause(1); %pretend this is a complicated calculation
%save the state of the random number genertor
stream = RandStream.getGlobalStream;
savedState = stream.State;
%save checkpoint
fprintf('Saving checkpoint\n');
save('checkpoint.mat');
fprintf('Completed iteration %d \n',count);
end
fprintf('The sum is %f \n',mysum);
Ensuring that the checkpoint save completes
Events that terminate our code can occur extremely quickly — a powercut for example. There is a risk that the machine was switched off while our check-point file was being written. How can we ensure that the file is complete?
The solution, which I found on the MATLAB checkpointing page of the Liverpool University Condor Pool site is to first write a temporary file and then rename it. That is, instead of
save('checkpoint.mat')/pre>
we do
if strcmp(computer,'PCWIN64') || strcmp(computer,'PCWIN')
%We are running on a windows machine
system( 'move /y checkpoint_tmp.mat checkpoint.mat' );
else
%We are running on Linux or Mac
system( 'mv checkpoint_tmp.mat checkpoint.mat' );
end
As the author of that page explains ‘The operating system should guarantee that the move command is “atomic” (in the sense that it is indivisible i.e. it succeeds completely or not at all) so that there is no danger of receiving a corrupt “half-written” checkpoint file from the job.’
Only checkpoint what is necessary
So far, we’ve been saving the entire MATLAB workspace in our checkpoint files and this hasn’t been a problem since our workspace hasn’t contained much. In general, however, the workspace might contain all manner of intermediate variables that we simply don’t need in order to restart where we left off. Saving the stuff that we might not need can be expensive.
For the sake of illustration, let’s skip 100 million random numbers before adding one to our sum. For reasons only known to ourselves, we store these numbers in an intermediate variable which we never do anything with. This array isn’t particularly large at 763 Megabytes but its existence slows down our checkpointing somewhat. The correct result of this variation of the calculation is 41.251376 if we set the starting seed to 0; something we can use to test our new checkpoint strategy.
Here’s the code
% A demo of how slow checkpointing can be if you include large intermediate variables
if exist( 'checkpoint.mat','file' ) % If a checkpoint file exists, load it
%use the saved RNG state
stream = RandStream.getGlobalStream;
stream.State = savedState;
else %otherwise, start from the beginning
fprintf('No checkpoint file found - starting from beginning\n');
mysum=0;
countmin=1;
rng(0); %Seed the random number generator for reproducible results
end
for count = countmin:100
%Create and store 100 million random numbers for no particular reason
randoms = rand(10000);
mysum = mysum + rand();
countmin = count+1; %If we load this checkpoint, we want to start on the next iteration
fprintf('Completed iteration %d \n',count);
if mod(count,25)==0
%save the state of the random number generator
stream = RandStream.getGlobalStream;
savedState = stream.State;
%save and time checkpoint
tic
save('checkpoint_tmp.mat');
if strcmp(computer,'PCWIN64') || strcmp(computer,'PCWIN')
%We are running on a windows machine
system( 'move /y checkpoint_tmp.mat checkpoint.mat' );
else
%We are running on Linux or Mac
system( 'mv checkpoint_tmp.mat checkpoint.mat' );
end
timing = toc;
fprintf('Checkpoint save took %f seconds\n',timing);
end
end
fprintf('The sum is %f \n',mysum);
On my Windows 7 Desktop, each checkpoint save takes around 17 seconds:
Completed iteration 25
1 file(s) moved.
Checkpoint save took 17.269897 seconds
It is not necessary to include that huge random matrix in a checkpoint file. If we are explicit in what we require, we can reduce the time taken to checkpoint significantly. Here, we change
save('checkpoint_tmp.mat');
to
save('checkpoint_tmp.mat','mysum','countmin','savedState');
This has a dramatic effect on check-pointing time:
Completed iteration 25
1 file(s) moved.
Checkpoint save took 0.033576 seconds
Here’s the final piece of code that uses everything discussed in this article
%Final checkpointing demo
if exist( 'checkpoint.mat','file' ) % If a checkpoint file exists, load it
%use the saved RNG state
stream = RandStream.getGlobalStream;
stream.State = savedState;
else %otherwise, start from the beginning
fprintf('No checkpoint file found - starting from beginning\n');
mysum=0;
countmin=1;
rng(0); %Seed the random number generator for reproducible results
end
for count = countmin:100
%Create and store 100 million random numbers for no particular reason
randoms = rand(10000);
mysum = mysum + rand();
countmin = count+1; %If we load this checkpoint, we want to start on the next iteration
fprintf('Completed iteration %d \n',count);
if mod(count,25)==0 %checkpoint every 25th iteration
%save the state of the random number generator
stream = RandStream.getGlobalStream;
savedState = stream.State;
%save and time checkpoint
tic
%only save the variables that are strictly necessary
save('checkpoint_tmp.mat','mysum','countmin','savedState');
%Ensure that the save completed
if strcmp(computer,'PCWIN64') || strcmp(computer,'PCWIN')
%We are running on a windows machine
system( 'move /y checkpoint_tmp.mat checkpoint.mat' );
else
%We are running on Linux or Mac
system( 'mv checkpoint_tmp.mat checkpoint.mat' );
end
timing = toc;
fprintf('Checkpoint save took %f seconds\n',timing);
end
end
fprintf('The sum is %f \n',mysum);
Parallel checkpointing
If your code includes parallel regions using constructs such as parfor or spmd, you might have to do more work to checkpoint correctly. I haven’t considered any of the potential issues that may arise in such code in this article
Checkpointing checklist
Here’s a reminder of everything you need to consider
• Test to ensure that the introduction of checkpointing doesn’t alter results
• Don’t checkpoint too often
• Take care when checkpointing code that involves random numbers – you need to explicitly save the state of the random number generator.
• Take measures to ensure that the checkpoint save is completed
• Only checkpoint what is necessary
• Code that includes parallel regions might require extra care
## Using the Portland PGI Compiler for MATLAB mex files in Windows #1
June 14th, 2012
I recently got access to a shiny new (new to me at least) set of compilers, The Portland PGI compiler suite which comes with a great set of technologies to play with including AVX vector support, CUDA for x86 and GPU pragma-based acceleration. So naturally, it wasn’t long before I wondered if I could use the PGI suite as compilers for MATLAB mex files. The bad news is that The Mathworks don’t support the PGI Compilers out of the box but that leads to the good news…I get to dig down and figure out how to add support for unsupported compilers.
In what follows I made use of MATLAB 2012a on 64bit Windows 7 with Version 12.5 of the PGI Portland Compiler Suite.
In order to set up a C mex-compiler in MATLAB you execute the following
mex -setup
which causes MATLAB to execute a Perl script at C:\Program Files\MATLAB\R2012a\bin\mexsetup.pm. This script scans the directory C:\Program Files\MATLAB\R2012a\bin\win64\mexopts looking for Perl scripts with the extension .stp and running whatever it finds. Each .stp file looks for a particular compiler. After all .stp files have been executed, a list of compilers found gets returned to the user. When the user chooses a compiler, the corresponding .bat file gets copied to the directory returned by MATLAB’s prefdir function. This sets up the compiler for use. All of this is nicely documented in the mexsetup.pm file itself.
So, I’ve had my first crack at this and the results are the following two files.
These are crude, and there’s probably lots missing/wrong but they seem to work. Copy them to C:\Program Files\MATLAB\R2012a\bin\win64\mexopts. The location of the compiler is hard-coded in pgi.stp so you’ll need to change the following line if your compiler location differs from mine
my $default_location = "C:\\Program Files\\PGI\\win64\\12.5\\bin"; Now, when you do mex -setup, you should get an entry PGI Workstation 12.5 64bit 12.5 in C:\Program Files\PGI\win64\12.5\bin which you can select as normal. An example compilation and some details. Let’s compile the following very simple mex file, mex_sin.c, using the PGI compiler which does little more than take an elementwise sine of the input matrix. #include <math.h> #include "mex.h" void mexFunction( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[] ) { double *in,*out; double dist,a,b; int rows,cols,outsize; int i,j,k; /*Get pointers to input matrix*/ in = mxGetPr(prhs[0]); /*Get rows and columns of input*/ rows = mxGetM(prhs[0]); cols = mxGetN(prhs[0]); /* Create output matrix */ outsize = rows*cols; plhs[0] = mxCreateDoubleMatrix(rows, cols, mxREAL); /* Assign pointer to the output */ out = mxGetPr(plhs[0]); for(i=0;i<outsize;i++){ out[i] = sin(in[i]); } } Compile using the -v switch to get verbose information about the compilation mex sin_mex.c -v You’ll see that the compiled mex file is actually a renamed .dll file that was compiled and linked with the following flags pgcc -c -Bdynamic -Minfo -fast pgcc --Mmakedll=export_all -L"C:\Program Files\MATLAB\R2012a\extern\lib\win64\microsoft" libmx.lib libmex.lib libmat.lib The switch –Mmakedll=export_all is actually not supported by PGI which makes this whole setup doubly unsupported! However, I couldn’t find a way to export the required symbols without modifying the mex source code so I lived with it. Maybe I’ll figure out a better way in the future. Let’s try the new function out >> a=[1 2 3]; >> mex_sin(a) Invalid MEX-file 'C:\Work\mex_sin.mexw64': The specified module could not be found. The reason for the error message is that a required PGI .dll file, pgc.dll, is not on my system path so I need to do the following in MATLAB. setenv('PATH', [getenv('PATH') ';C:\Program Files\PGI\win64\12.5\bin\']); This fixes things >> mex_sin(a) ans = 0.8415 0.9093 0.1411 Performance I took a quick look at the performance of this mex function using my quad-core, Sandy Bridge laptop. I highly doubted that I was going to beat MATLAB’s built in sin function (which is highly optimised and multithreaded) with so little work and I was right: >> a=rand(1,100000000); >> tic;mex_sin(a);toc Elapsed time is 1.320855 seconds. >> tic;sin(a);toc Elapsed time is 0.486369 seconds. That’s not really a fair comparison though since I am purposely leaving mutithreading out of the PGI mex equation for now. It’s a much fairer comparison to compare the exact same mex file using different compilers so let’s do that. I created three different compiled mex routines from the source code above using the three compilers installed on my laptop and performed a very crude time test as follows >> a=rand(1,100000000); >> tic;mex_sin_pgi(a);toc %PGI 12.5 run 1 Elapsed time is 1.317122 seconds. >> tic;mex_sin_pgi(a);toc %PGI 12.5 run 2 Elapsed time is 1.338271 seconds. >> tic;mex_sin_vs(a);toc %Visual Studio 2008 run 1 Elapsed time is 1.459463 seconds. >> tic;mex_sin_vs(a);toc Elapsed time is 1.446947 seconds. %Visual Studio 2008 run 2 >> tic;mex_sin_intel(a);toc %Intel Compiler 12.0 run 1 Elapsed time is 0.907018 seconds. >> tic;mex_sin_intel(a);toc %Intel Compiler 12.0 run 2 Elapsed time is 0.860218 seconds. PGI did a little better than Visual Studio 2008 but was beaten by Intel. I’m hoping that I’ll be able to get more performance out of the PGI compiler as I learn more about the compilation flags. Getting PGI to make use of SSE extensions Part of the output of the mex sin_mex.c -v compilation command is the following notice mexFunction: 23, Loop not vectorized: data dependency This notice is a result of the -Minfo compilation switch and indicates that the PGI compiler can’t determine if the in and out arrays overlap or not. If they don’t overlap then it would be safe to unroll the loop and make use of SSE or AVX instructions to make better use of my Sandy Bridge processor. This should hopefully speed things up a little. As the programmer, I am sure that the two arrays don’t overlap so I need to give the compiler a hand. One way to do this would be to modify the pgi.dat file to include the compilation switch -Msafeptr which tells the compiler that arrays never overlap anywhere. This might not be a good idea since it may not always be true so I decided to be more cautious and make use of the restrict keyword. That is, I changed the mex source code so that double *in,*out; becomes double * restrict in,* restrict out; Now when I compile using the PGI compiler, the notice from -Mifno becomes mexFunction: 23, Generated 3 alternate versions of the loop Generated vector sse code for the loop Generated a prefetch instruction for the loop which demonstrates that the compiler is much happier! So, what did this do for performance? >> tic;mex_sin_pgi(a);toc Elapsed time is 1.450002 seconds. >> tic;mex_sin_pgi(a);toc Elapsed time is 1.460536 seconds. This is slower than when SSE instructions weren’t being used which isn’t what I was expecting at all! If anyone has any insight into what’s going on here, I’d love to hear from you. Future Work I’m happy that I’ve got this compiler working in MATLAB but there is a lot to do including: • Tidy up the pgi.dat and pgi.stp files so that they look and act more professionally. • Figure out the best set of compiler switches to use– it is almost certain that what I’m using now is sub-optimal since I am new to the PGI compiler. • Get OpenMP support working. I tried using the -Mconcur compilation flag which auto-parallelised the loop but it crashed MATLAB when I ran it. This needs investigating • Get PGI accelerator support working so I can offload work to the GPU. • Figure out why the SSE version of this function is slower than the non-SSE version • Figure out how to determine whether or not the compiler is emitting AVX instructions. The documentation suggests that if the compiler is called on a Sandy Bridge machine, and if vectorisation is possible then it will produce AVX instructions but AVX is not mentioned in the output of -Minfo. Nothing changes if you explicity set the target to Sandy Bridge with the compiler switch tp sandybridge64. Look out for more articles on this in the future. Related WalkingRandomly Articles My setup • Laptop model: Dell XPS L702X • CPU: Intel Core i7-2630QM @2Ghz software overclockable to 2.9Ghz. 4 physical cores but total 8 virtual cores due to Hyperthreading. • GPU: GeForce GT 555M with 144 CUDA Cores. Graphics clock: 590Mhz. Processor Clock:1180 Mhz. 3072 Mb DDR3 Memeory • RAM: 8 Gb • OS: Windows 7 Home Premium 64 bit. • MATLAB: 2012a • PGI Compiler: 12.5 ## MATLAB mex functions using the NAG C Library in Windows October 24th, 2011 The NAG C Library is one of the largest commercial collections of numerical software currently available and I often find it very useful when writing MATLAB mex files. “Why is that?” I hear you ask. One of the main reasons for writing a mex file is to gain more speed over native MATLAB. However, one of the main problems with writing mex files is that you have to do it in a low level language such as Fortran or C and so you lose much of the ease of use of MATLAB. In particular, you lose straightforward access to most of the massive collections of MATLAB routines that you take for granted. Technically speaking that’s a lie because you could use the mex function mexCallMATLAB to call a MATLAB routine from within your mex file but then you’ll be paying a time overhead every time you go in and out of the mex interface. Since you are going down the mex route in order to gain speed, this doesn’t seem like the best idea in the world. This is also the reason why you’d use the NAG C Library and not the NAG Toolbox for MATLAB when writing mex functions. One way out that I use often is to take advantage of the NAG C library and it turns out that it is extremely easy to add the NAG C library to your mex projects on Windows. Let’s look at a trivial example. The following code, nag_normcdf.c, uses the NAG function nag_cumul_normal to produce a simplified version of MATLAB’s normcdf function (laziness is all that prevented me from implementing a full replacement). /* A simplified version of normcdf that uses the NAG C library * Written to demonstrate how to compile MATLAB mex files that use the NAG C Library * Only returns a normcdf where mu=0 and sigma=1 * October 2011 Michael Croucher * www.walkingrandomly.com */ #include <math.h> #include "mex.h" #include "nag.h" #include "nags.h" void mexFunction( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[] ) { double *in,*out; int rows,cols,num_elements,i; if(nrhs>1) { mexErrMsgIdAndTxt("NAG:BadArgs","This simplified version of normcdf only takes 1 input argument"); } /*Get pointers to input matrix*/ in = mxGetPr(prhs[0]); /*Get rows and columns of input matrix*/ rows = mxGetM(prhs[0]); cols = mxGetN(prhs[0]); num_elements = rows*cols; /* Create output matrix */ plhs[0] = mxCreateDoubleMatrix(rows, cols, mxREAL); /* Assign pointer to the output */ out = mxGetPr(plhs[0]); for(i=0; i<num_elements; i++){ out[i] = nag_cumul_normal(in[i]); } } To compile this in MATLAB, just use the following command mex nag_normcdf.c CLW6I09DA_nag.lib If your system is set up the same as mine then the above should ‘just work’ (see System Information at the bottom of this post). The new function works just as you would expect it to >> format long >> format compact >> nag_normcdf(1) ans = 0.841344746068543 Compare the result to normcdf from the statistics toolbox >> normcdf(1) ans = 0.841344746068543 So far so good. I could stop the post here since all I really wanted to do was say ‘The NAG C library is useful for MATLAB mex functions and it’s a doddle to use – here’s a toy example and here’s the mex command to compile it’ However, out of curiosity, I looked to see if my toy version of normcdf was any faster than The Mathworks’ version. Let there be 10 million numbers: >> x=rand(1,10000000); Let’s time how long it takes MATLAB to take the normcdf of those numbers >> tic;y=normcdf(x);toc Elapsed time is 0.445883 seconds. >> tic;y=normcdf(x);toc Elapsed time is 0.405764 seconds. >> tic;y=normcdf(x);toc Elapsed time is 0.366708 seconds. >> tic;y=normcdf(x);toc Elapsed time is 0.409375 seconds. Now let’s look at my toy-version that uses NAG. >> tic;y=nag_normcdf(x);toc Elapsed time is 0.544642 seconds. >> tic;y=nag_normcdf(x);toc Elapsed time is 0.556883 seconds. >> tic;y=nag_normcdf(x);toc Elapsed time is 0.553920 seconds. >> tic;y=nag_normcdf(x);toc Elapsed time is 0.540510 seconds. So my version is slower! Never mind, I’ll just make my version parallel using OpenMP – Here is the code: nag_normcdf_openmp.c /* A simplified version of normcdf that uses the NAG C library * Written to demonstrate how to compile MATLAB mex files that use the NAG C Library * Only returns a normcdf where mu=0 and sigma=1 * October 2011 Michael Croucher * www.walkingrandomly.com */ #include <math.h> #include "mex.h" #include "nag.h" #include "nags.h" #include <omp.h> void do_calculation(double in[],double out[],int num_elements) { int i,tid; #pragma omp parallel for shared(in,out,num_elements) private(i,tid) for(i=0; i<num_elements; i++){ out[i] = nag_cumul_normal(in[i]); } } void mexFunction( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[] ) { double *in,*out; int rows,cols,num_elements; if(nrhs>1) { mexErrMsgIdAndTxt("NAG_NORMCDF:BadArgs","This simplified version of normcdf only takes 1 input argument"); } /*Get pointers to input matrix*/ in = mxGetPr(prhs[0]); /*Get rows and columns of input matrix*/ rows = mxGetM(prhs[0]); cols = mxGetN(prhs[0]); num_elements = rows*cols; /* Create output matrix */ plhs[0] = mxCreateDoubleMatrix(rows, cols, mxREAL); /* Assign pointer to the output */ out = mxGetPr(plhs[0]); do_calculation(in,out,num_elements); } Compile that with mex COMPFLAGS="$COMPFLAGS /openmp" nag_normcdf_openmp.c CLW6I09DA_nag.lib
and on my quad-core machine I get the following timings
>> tic;y=nag_normcdf_openmp(x);toc
Elapsed time is 0.237925 seconds.
>> tic;y=nag_normcdf_openmp(x);toc
Elapsed time is 0.197531 seconds.
>> tic;y=nag_normcdf_openmp(x);toc
Elapsed time is 0.206511 seconds.
>> tic;y=nag_normcdf_openmp(x);toc
Elapsed time is 0.211416 seconds.
This is faster than MATLAB and so normal service is resumed :)
System Information
• 64bit Windows 7
• MATLAB 2011b
• NAG C Library Mark 9 – CLW6I09DAL
• Visual Studio 2008
• Intel Core i7-2630QM processor
## MATLAB GPU / CUDA experiences and tutorials on my laptop – Introduction
July 27th, 2011
These days it seems that you can’t talk about scientific computing for more than 5 minutes without somone bringing up the topic of Graphics Processing Units (GPUs). Originally designed to make computer games look pretty, GPUs are massively parallel processors that promise to revolutionise the way we compute.
A brief glance at the specification of a typical laptop suggests why GPUs are the new hotness in numerical computing. Take my new one for instance, a Dell XPS L702X, which comes with a Quad-Core Intel i7 Sandybridge processor running at up to 2.9Ghz and an NVidia GT 555M with a whopping 144 CUDA cores. If you went back in time a few years and told a younger version of me that I’d soon own a 148 core laptop then young Mike would be stunned. He’d also be wondering ‘What’s the catch?’
Of course the main catch is that all processor cores are not created equally. Those 144 cores in my GPU are, individually, rather wimpy when compared to the ones in the Intel CPU. It’s the sheer quantity of them that makes the difference. The question at the forefront of my mind when I received my shiny new laptop was ‘Just how much of a difference?’
Now I’ve seen lots of articles that compare CPUs with GPUs and the GPUs always win…..by a lot! Dig down into the meat of these articles, however, and it turns out that things are not as simple as they seem. Roughly speaking, the abstract of some them could be summed up as ‘We took a serial algorithm written by a chimpanzee for an old, outdated CPU and spent 6 months parallelising and fine tuning it for a top of the line GPU. Our GPU version is up to 150 times faster!
Well it would be wouldn’t it?! In other news, Lewis Hamilton can drive his F1 supercar around Silverstone faster than my dad can in his clapped out 12 year old van! These articles are so prevalent that csgillespie.wordpress.com recently published an excellent article that summarised everything you should consider when evaluating them. What you do is take the claimed speed-up, apply a set of common sense questions and thus determine a realistic speedup. That factor of 150 can end up more like a factor of 8 once you think about it the right way.
That’s not to say that GPUs aren’t powerful or useful…it’s just that maybe they’ve been hyped up a bit too much!
So anyway, back to my laptop. It doesn’t have a top of the range GPU custom built for scientific computing, instead it has what Notebookcheck.net refers to as a fast middle class graphics card for laptops. It’s got all of the required bits though….144 cores and CUDA compute level 2.1 so surely it can whip the built in CPU even if it’s just by a little bit?
I decided to find out with a few randomly chosen tests. I wasn’t aiming for the kind of rigor that would lead to a peer reviewed journal but I did want to follow some basic rules at least
• I will only choose algorithms that have been optimised and parallelised for both the CPU and the GPU.
• I will release the source code of the tests so that they can be critised and repeated by others.
• I’ll do the whole thing in MATLAB using the new GPU functionality in the parallel computing toolbox. So, to repeat my calculations all you need to do is copy and paste some code. Using MATLAB also ensures that I’m using good quality code for both CPU and GPU.
The articles
This is the introduction to a set of articles about GPU computing on MATLAB using the parallel computing toolbox. Links to the rest of them are below and more will be added in the future.
External links of interest to MATLABers with an interest in GPUs
## Complex Power Towers (Or ‘mucking around with Mathematica’)
October 30th, 2010
Some time ago now, Sam Shah of Continuous Everywhere but Differentiable Nowhere fame discussed the standard method of obtaining the square root of the imaginary unit, i, and in the ensuing discussion thread someone asked the question “What is i^i – that is what is i to the power i?”
Sam immediately came back with the answer e^(-pi/2) = 0.207879…. which is one of the answers but as pointed out by one of his readers, Adam Glesser, this is just one of the infinite number of potential answers that all have the form e^{-(2k+1) pi/2} where k is an integer. Sam’s answer is the principle value of i^i (incidentally this is the value returned by google calculator if you google i^i – It is also the value returned by Mathematica and MATLAB). Life gets a lot more complicated when you move to the complex plane but it also gets a lot more interesting too.
While on the train into work one morning I was thinking about Sam’s blog post and wondered what the principal value of i^i^i (i to the power i to the power i) was equal to. Mathematica quickly provided the answer:
N[I^I^I]
0.947159+0.320764 I
So i is imaginary, i^i is real and i^i^i is imaginary again. Would i^i^i^i be real I wondered – would be fun if it was. Let’s see:
N[I^I^I^I]
0.0500922+0.602117 I
gah – a conjecture bites the dust – although if I am being honest it wasn’t a very good one. Still, since I have started making ‘power towers’ I may as well continue and see what I can see. Why am I calling them power towers? Well, the calculation above could be written as follows:
As I add more and more powers, the left hand side of the equation will tower up the page….Power Towers. We now have a sequence of the first four power towers of i:
i = i
i^i = 0.207879
i^i^i = 0.947159 + 0.32076 I
i^i^i^i = 0.0500922+0.602117 I
### Sequences of power towers
“Will this sequence converge or diverge?”, I wondered. I wasn’t in the mood to think about a rigorous mathematical proof, I just wanted to play so I turned back to Mathematica. First things first, I needed to come up with a way of making an arbitrarily large power tower without having to do a lot of typing. Mathematica’s Nest function came to the rescue and the following function allows you to create a power tower of any size for any number, not just i.
tower[base_, size_] := Nest[N[(base^#)] &, base, size]
Now I can find the first term of my series by doing
In[1]:= tower[I, 0]
Out[1]= I
Or the 5th term by doing
In[2]:= tower[I, 4]
Out[2]= 0.387166 + 0.0305271 I
To investigate convergence I needed to create a table of these. Maybe the first 100 towers would do:
ColumnForm[
Table[tower[I, n], {n, 1, 100}]
]
The last few values given by the command above are
0.438272+ 0.360595 I
0.438287+ 0.360583 I
0.438287+ 0.3606 I
0.438275+ 0.360591 I
0.438289+ 0.360588 I
Now this is interesting – As I increased the size of the power tower, the result seemed to be converging to around 0.438 + 0.361 i. Further investigation confirms that the sequence of power towers of i converges to 0.438283+ 0.360592 i. If you were to ask me to guess what I thought would happen with large power towers like this then I would expect them to do one of three things – diverge to infinity, stay at 1 forever or quickly converge to 0 so this is unexpected behaviour (unexpected to me at least).
### They converge, but how?
My next thought was ‘How does it converge to this value? In other words, ‘What path through the complex plane does this sequence of power towers take?” Time for a graph:
tower[base_, size_] := Nest[N[(base^#)] &, base, size];
complexSplit[x_] := {Re[x], Im[x]};
ListPlot[Map[complexSplit, Table[tower[I, n], {n, 0, 49, 1}]],
PlotRange -> All]
Who would have thought you could get a spiral from power towers? Very nice! So the next question is ‘What would happen if I took a different complex number as my starting point?’ For example – would power towers of (0.5 + i) converge?’
The answer turns out to be yes – power towers of (0.5 + I) converge to 0.541199+ 0.40681 I but the resulting spiral looks rather different from the one above.
tower[base_, size_] := Nest[N[(base^#)] &, base, size];
complexSplit[x_] := {Re[x], Im[x]};
ListPlot[Map[complexSplit, Table[tower[0.5 + I, n], {n, 0, 49, 1}]],
PlotRange -> All]
### The zoo of power tower spirals
So, taking power towers of two different complex numbers results in two qualitatively different ‘convergence spirals’. I wondered how many different spiral types I might find if I consider the entire complex plane? I already have all of the machinery I need to perform such an investigation but investigation is much more fun if it is interactive. Time for a Manipulate
complexSplit[x_] := {Re[x], Im[x]};
tower[base_, size_] := Nest[N[(base^#)] &, base, size];
generatePowerSpiral[p_, nmax_] :=
Map[complexSplit, Table[tower[p, n], {n, 0, nmax-1, 1}]];
Manipulate[const = p[[1]] + p[[2]] I;
ListPlot[generatePowerSpiral[const, n],
PlotRange -> {{-2, 2}, {-2, 2}}, Axes -> ax,
Epilog -> Inset[Framed[const], {-1.5, -1.5}]], {{n, 100,
"Number of terms"}, 1, 200, 1,
Appearance -> "Labeled"}, {{ax, True, "Show axis"}, {True,
False}}, {{p, {0, 1.5}}, Locator}]
After playing around with this Manipulate for a few seconds it became clear to me that there is quite a rich diversity of these convergence spirals. Here are a couple more
Some of them take a lot longer to converge than others and then there are those that don’t converge at all:
### Optimising the code a little
Before I could investigate convergence any further, I had a problem to solve: Sometimes the Manipulate would completely freeze and a message eventually popped up saying “One or more dynamic objects are taking excessively long to finish evaluating……” What was causing this I wondered?
Well, some values give overflow errors:
In[12]:= generatePowerSpiral[-1 + -0.5 I, 200]
General::ovfl: Overflow occurred in computation. >>
General::ovfl: Overflow occurred in computation. >>
General::ovfl: Overflow occurred in computation. >>
General::stop: Further output of General::ovfl will be suppressed during this calculation. >>
Could errors such as this be making my Manipulate unstable? Let’s see how long it takes Mathematica to deal with the example above
AbsoluteTiming[ListPlot[generatePowerSpiral[-1 -0.5 I, 200]]]
On my machine, the above command typically takes around 0.08 seconds to complete compared to 0.04 seconds for a tower that converges nicely; it’s slower but not so slow that it should break Manipulate. Still, let’s fix it anyway.
Look at the sequence of values that make up this problematic power tower
generatePowerSpiral[-0.8 + 0.1 I, 10]
{{-0.8, 0.1}, {-0.668442, -0.570216}, {-2.0495, -6.11826},
{2.47539*10^7,1.59867*10^8}, {2.068155430437682*10^-211800874,
-9.83350984373519*10^-211800875}, {Overflow[], 0}, {Indeterminate,
Indeterminate}, {Indeterminate, Indeterminate}, {Indeterminate,
Indeterminate}, {Indeterminate, Indeterminate}}
Everything is just fine until the term {Overflow[],0} is reached; after which we are just wasting time. Recall that the functions I am using to create these sequences are
complexSplit[x_] := {Re[x], Im[x]};
tower[base_, size_] := Nest[N[(base^#)] &, base, size];
generatePowerSpiral[p_, nmax_] :=
Map[complexSplit, Table[tower[p, n], {n, 0, nmax-1, 1}]];
The first thing I need to do is break out of tower’s Nest function as soon as the result stops being a complex number and the NestWhile function allows me to do this. So, I could redefine the tower function to be
tower[base_, size_] :=
NestWhile[N[(base^#)] &, base, MatchQ[#, _Complex] &, 1, size]
However, I can do much better than that since my code so far is massively inefficient. Say I already have the first n terms of a tower sequence; to get the (n+1)th term all I need to do is a single power operation but my code is starting from the beginning and doing n power operations instead. So, to get the 5th term, for example, my code does this
I^I^I^I^I
(4th term)^I
The function I need to turn to is yet another variant of Nest – NestWhileList
fasttowerspiral[base_, size_] :=
Quiet[Map[complexSplit,
NestWhileList[N[(base^#)] &, base, MatchQ[#, _Complex] &, 1,
size, -1]]];
The Quiet function is there to prevent Mathematica from warning me about the Overflow error. I could probably do better than this and catch the Overflow error coming before it happens but since I’m only mucking around, I’ll leave that to an interested reader. For now it’s enough for me to know that the code is much faster than before:
(*Original Function*)
AbsoluteTiming[generatePowerSpiral[I, 200];]
{0.036254, Null}
(*Improved Function*)
AbsoluteTiming[fasttowerspiral[I, 200];]
{0.001740, Null}
A factor of 20 will do nicely!
### Making Mathematica faster by making it stupid
I’m still not done though. Even with these optimisations, it can take a massive amount of time to compute some of these power tower spirals. For example
spiral = fasttowerspiral[-0.77 - 0.11 I, 100];
takes 10 seconds on my machine which is thousands of times slower than most towers take to compute. What on earth is going on? Let’s look at the first few numbers to see if we can find any clues
In[34]:= spiral[[1 ;; 10]]
Out[34]= {{-0.77, -0.11}, {-0.605189, 0.62837}, {-0.66393,
7.63862}, {1.05327*10^10,
7.62636*10^8}, {1.716487392960862*10^-155829929,
2.965988537183398*10^-155829929}, {1., \
-5.894184073663391*10^-155829929}, {-0.77, -0.11}, {-0.605189,
0.62837}, {-0.66393, 7.63862}, {1.05327*10^10, 7.62636*10^8}}
The first pair that jumps out at me is {1.716487392960862*10^-155829929, 2.965988537183398*10^-155829929} which is so close to {0,0} that it’s not even funny! So close, in fact, that they are not even double precision numbers any more. Mathematica has realised that the calculation was going to underflow and so it caught it and returned the result in arbitrary precision.
Arbitrary precision calculations are MUCH slower than double precision ones and this is why this particular calculation takes so long. Mathematica is being very clever but its cleverness is costing me a great deal of time and not adding much to the calculation in this case. I reckon that I want Mathematica to be stupid this time and so I’ll turn off its underflow safety net.
SetSystemOptions["CatchMachineUnderflow" -> False]
Now our problematic calculation takes 0.000842 seconds rather than 10 seconds which is so much faster that it borders on the astonishing. The results seem just fine too!
### When do the power towers converge?
We have seen that some towers converge while others do not. Let S be the set of complex numbers which lead to convergent power towers. What might S look like? To determine that I have to come up with a function that answers the question ‘For a given complex number z, does the infinite power tower converge?’ The following is a quick stab at such a function
convergeQ[base_, size_] :=
If[Length[
Quiet[NestWhileList[N[(base^#)] &, base, Abs[#1 - #2] > 0.01 &,
2, size, -1]]] < size, 1, 0];
The tolerance I have chosen, 0.01, might be a little too large but these towers can take ages to converge and I’m more interested in speed than accuracy right now so 0.01 it is. convergeQ returns 1 when the tower seems to converge in at most size steps and 0 otherwise.:
In[3]:= convergeQ[I, 50]
Out[3]= 1
In[4]:= convergeQ[-1 + 2 I, 50]
Out[4]= 0
So, let’s apply this to a section of the complex plane.
towerFract[xmin_, xmax_, ymin_, ymax_, step_] :=
ArrayPlot[
Table[convergeQ[x + I y, 50], {y, ymin, ymax, step}, {x, xmin, xmax,step}]]
towerFract[-2, 2, -2, 2, 0.1]
That looks like it might be interesting, possibly even fractal, behaviour but I need to increase the resolution and maybe widen the range to see what’s really going on. That’s going to take quite a bit of calculation time so I need to optimise some more.
### Going Parallel
There is no point in having machines with two, four or more processor cores if you only ever use one and so it is time to see if we can get our other cores in on the act.
It turns out that this calculation is an example of a so-called embarrassingly parallel problem and so life is going to be particularly easy for us. Basically, all we need to do is to give each core its own bit of the complex plane to work on, collect the results at the end and reap the increase in speed. Here’s the full parallel version of the power tower fractal code
(*Complete Parallel version of the power tower fractal code*)
convergeQ[base_, size_] :=
If[Length[
Quiet[NestWhileList[N[(base^#)] &, base, Abs[#1 - #2] > 0.01 &,
2, size, -1]]] < size, 1, 0];
LaunchKernels[];
DistributeDefinitions[convergeQ];
ParallelEvaluate[SetSystemOptions["CatchMachineUnderflow" -> False]];
towerFractParallel[xmin_, xmax_, ymin_, ymax_, step_] :=
ArrayPlot[
ParallelTable[
convergeQ[x + I y, 50], {y, ymin, ymax, step}, {x, xmin, xmax, step}
, Method -> "CoarsestGrained"]]
This code is pretty similar to the single processor version so let’s focus on the parallel modifications. My convergeQ function is no different to the serial version so nothing new to talk about there. So, the first new code is
LaunchKernels[];
This launches a set of parallel Mathematica kernels. The amount that actually get launched depends on the number of cores on your machine. So, on my dual core laptop I get 2 and on my quad core desktop I get 4.
DistributeDefinitions[convergeQ];
All of those parallel kernels are completely clean in that they don’t know about my user defined convergeQ function. This line sends the definition of convergeQ to all of the freshly launched parallel kernels.
ParallelEvaluate[SetSystemOptions["CatchMachineUnderflow" -> False]];
Here we turn off Mathematica’s machine underflow safety net on all of our parallel kernels using the ParallelEvaluate function.
That’s all that is necessary to set up the parallel environment. All that remains is to change Map to ParallelMap and to add the argument Method -> “CoarsestGrained” which basically says to Mathematica ‘Each sub-calculation will take a tiny amount of time to perform so you may as well send each core lots to do at once’ (click here for a blog post of mine where this is discussed further).
That’s all it took to take this embarrassingly parallel problem from a serial calculation to a parallel one. Let’s see if it worked. The test machine for what follows contains a T5800 Intel Core 2 Duo CPU running at 2Ghz on Ubuntu (if you want to repeat these timings then I suggest you read this blog post first or you may find the parallel version going slower than the serial one). I’ve suppressed the output of the graphic since I only want to time calculation and not rendering time.
(*Serial version*)
In[3]= AbsoluteTiming[towerFract[-2, 2, -2, 2, 0.1];]
Out[3]= {0.672976, Null}
(*Parallel version*)
In[4]= AbsoluteTiming[towerFractParallel[-2, 2, -2, 2, 0.1];]
Out[4]= {0.532504, Null}
In[5]= speedup = 0.672976/0.532504
Out[5]= 1.2638
I was hoping for a bit more than a factor of 1.26 but that’s the way it goes with parallel programming sometimes. The speedup factor gets a bit higher if you increase the size of the problem though. Let’s increase the problem size by a factor of 100.
towerFractParallel[-2, 2, -2, 2, 0.01]
The above calculation took 41.99 seconds compared to 63.58 seconds for the serial version resulting in a speedup factor of around 1.5 (or about 34% depending on how you want to look at it).
### Other optimisations
I guess if I were really serious about optimising this problem then I could take advantage of the symmetry along the x axis or maybe I could utilise the fact that if one point in a convergence spiral converges then it follows that they all do. Maybe there are more intelligent ways to test for convergence or maybe I’d get a big speed increase from programming in C or F#? If anyone is interested in having a go at improving any of this and succeeds then let me know.
I’m not going to pursue any of these or any other optimisations, however, since the above exploration is what I achieved in a single train journey to work (The write-up took rather longer though). I didn’t know where I was going and I only worried about optimisation when I had to. At each step of the way the code was fast enough to ensure that I could interact with the problem at hand.
Being mostly ‘fast enough’ with minimal programming effort is one of the reasons I like playing with Mathematica when doing explorations such as this.
### Treading where people have gone before
So, back to the power tower story. As I mentioned earlier, I did most of the above in a single train journey and I didn’t have access to the internet. I was quite excited that I had found a fractal from such a relatively simple system and very much felt like I had discovered something for myself. Would this lead to something that was publishable I wondered?
It turns out that power towers have been thoroughly investigated and the act of forming a tower is called tetration. I learned that when a tower converges there is an analytical formula that gives what it will converge to:
*** QuickLaTeX cannot compile formula:
h(z) = -\frac{W(-ln z)}{ln(z)
*** Error message:
File ended while scanning use of \frac .
Emergency stop.
Where W is the Lambert W function (click here for a cool poster for this function). I discovered that other people had already made Wolfram Demonstrations for power towers too
There is even a website called tetration.org that shows ‘my’ fractal in glorious technicolor. Nothing new under the sun eh?
### Parting shots
Well, I didn’t discover anything new but I had a bit of fun along the way. Here’s the final Manipulate I came up with
Manipulate[const = p[[1]] + p[[2]] I;
If[hz,
ListPlot[fasttowerspiral[const, n], PlotRange -> {{-2, 2}, {-2, 2}},
Axes -> ax,
Epilog -> {{PointSize[Large], Red,
Point[complexSplit[N[h[const]]]]}, {Inset[
Framed[N[h[const]]], {-1, -1.5}]}}]
, ListPlot[fasttowerspiral[const, n],
PlotRange -> {{-2, 2}, {-2, 2}}, Axes -> ax]
]
, {{n, 100, "Number of terms"}, 1, 500, 1, Appearance -> "Labeled"}
, {{ax, True, "Show axis"}, {True, False}}
, {{hz, True, "Show h(z)"}, {True, False}}
, {{p, {0, 1.5}}, Locator}
, Initialization :> (
SetSystemOptions["CatchMachineUnderflow" -> False];
complexSplit[x_] := {Re[x], Im[x]};
fasttowerspiral[base_, size_] :=
Quiet[Map[complexSplit,
NestWhileList[N[(base^#)] &, base, MatchQ[#, _Complex] &, 1,
size, -1]]];
h[z_] := -ProductLog[-Log[z]]/Log[z];
)
]
and here’s a video of a zoom into the tetration fractal that I made using spare cycles on Manchester University’s condor pool.
If you liked this blog post then you may also enjoy: | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.32098644971847534, "perplexity": 2378.3111394024377}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-17/segments/1524125948126.97/warc/CC-MAIN-20180426105552-20180426125552-00009.warc.gz"} |
http://hal.in2p3.fr/in2p3-00723332 | # Dilepton production in proton-proton and Pb+Pb collisions at sqrt(s_NN)=2.76 TeV
Abstract : We study e^+e^- pair production in proton-proton and central Pb+Pb collisions at sqrt(s_NN)=2.76 TeV within two models: an extended statistical hadronization model (SHM) and the Parton-Hadron-String Dynamics (PHSD) transport approach. We find that the PHSD calculations roughly agree with the dilepton spectrum from hadronic sources with the 'cocktail' estimates from the statistical hadronization model matched to available data at LHC energies. The dynamical simulations within the PHSD show a moderate increase of the low mass dilepton yield essentially due to the in-medium modification of the rho-meson. Furthermore, pronounced traces of the partonic degrees of freedom are found in the PHSD results in the intermediate mass regime. The dilepton production from the strongly interacting quark-gluon plasma (sQGP) exceeds that from the semi-leptonic decays of open charm and bottom mesons. Additionally, we observe that a transverse momentum cut of 1 GeV/c further suppresses the relative contribution of the heavy meson decays to the dilepton yield, such that the sQGP radiation strongly dominates the spectrum for masses from 1 to 3 GeV, allowing a closer look at the electromagnetic emissivity of the partonic plasma in the early phase of Pb+Pb collisions.
Document type :
Journal articles
Physical Review C, American Physical Society, 2013, 87, pp.014905. <10.1103/PhysRevC.87.014905>
Domain :
http://hal.in2p3.fr/in2p3-00723332
Contributor : Dominique Girod <>
Submitted on : Thursday, August 9, 2012 - 10:16:07 AM
Last modification on : Tuesday, March 5, 2013 - 1:43:15 PM
### Citation
O. Linnyk, W. Cassing, J. Manninen, E. L. Bratkovskaya, Pol-Bernard Gossiaux, et al.. Dilepton production in proton-proton and Pb+Pb collisions at sqrt(s_NN)=2.76 TeV. Physical Review C, American Physical Society, 2013, 87, pp.014905. <10.1103/PhysRevC.87.014905>. <in2p3-00723332>
### Metrics
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http://mathoverflow.net/questions/62630/what-theorem-of-liouvilles-is-gian-carlo-rota-referring-to-here | # What theorem of Liouville's is Gian-Carlo Rota referring to here?
I am very curious about this remark in Lesson Four of Rota's talk, Ten Lessons I Wish I Had Learned Before I Started Teaching Differential Equations:
"For second order linear differential equations, formulas for changes of dependent and independent variables are known, but such formulas are not to be found in any book written in this century, even though they are of the utmost usefulness.
"Liouville discovered a differential polynomial in the coefficients of a second order linear differential equation which he called the invariant. He proved that two linear second order differential equations can be transformed into each other by changes of variables if and only if they have the same invariant. This theorem is not to be found in any text. It was stated as an exercise in the first edition of my book, but my coauthor insisted that it be omitted from later editions."
Does anyone know where to find this theorem?
-
Hyperbole is the worst thing in the universe, and Gian-Carlo Rota used it frequently. In this article, he wrote: "The Administrative Director of the MIT mathematics department, who exercises supreme authority upon the faculty's teaching, has only to wave a copy of my book at me, while staring at me in silence. At her prompting, I bow and fall into line; I will be the lecturer in the dreaded course for one more year, and[...]". Some years ago I called this sentence to the attention of the said "administrative director, and she said there's not a word of truth in it. – Michael Hardy Apr 22 '11 at 21:46
Hyperbole is far from the worst thing in the universe. Rota's flair for the dramatic is part of what made him such an engaging lecturer. – AVS Apr 23 '11 at 2:03
Um.....AVS, did you miss something? But then, who needs rhetorical questions? – Michael Hardy Apr 23 '11 at 5:58
BTW, I plagiarized that line from a facebook friend. He wrote it on his wall and put the period after the word "universe" and didn't go on from there. Maybe adding more stuff confuses the issue. – Michael Hardy Apr 23 '11 at 6:04
I apologize for misinterpreting your comment. Your meaning and tone would have been entirely clear had you ended your comment at the word universe as you suggest (and I'm sure Rota would have heartily approved). – AVS Apr 23 '11 at 9:43
See E. Hille, Ordinary differential equations in the complex domain, Wiley, New York, 1976. The Liouville transformation is given on Page 179. The invariant mentioned by Rota is the function $Q(z)$ appearing as a coefficient of the equation in the canonical form. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8032601475715637, "perplexity": 543.5161413945444}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1405997904391.23/warc/CC-MAIN-20140722025824-00153-ip-10-33-131-23.ec2.internal.warc.gz"} |
https://healthpolicy.fas.harvard.edu/people/samuel-moy | # Samuel Moy
Data Scientist, Uber
Dissertation Title: "Essays on Regulation in Health Care Markets"This dissertation consists of three chapters studying regulation of payer and provider health care markets.
The first chapter studies how the market definitions of the Affordable Care Act health insurance exchanges affect the function of these insurance markets. Using a county-level matching design among states that use the federally facilitated marketplace, I show that counties included in the same market as large metropolitan areas tend to offer lower premiums and deductibles; however, this comes at the cost of narrower provider networks. Given the nature of premium subsidies on the exchanges, the benefits of lower premiums and deductibles primarily accrue to the federal government. These effects are consistent with a form of market "unraveling": the presence of greater insurer competition in larger markets creates conditions under which no insurer can find it profitable to offer a plan that is generous on non-price dimensions.
In the second chapter, I develop a micro-founded structural model of the exchanges in the spirit of (Ho and Lee 2017). I calibrate the model using data from Commonwealth Care - the Massachusetts precursor to the ACA; I then use the model to simulate a counterfactual policy change to the geographic insurance market definitions. My simulations show that larger markets significantly attenuate hospitals' market power by altering insurers' threat points, leading to lower prices paid to hospitals. When the state of Massachusetts is divided into five separate rating areas, the average price paid for an inpatient admission is $15,333, whereas under a single state-wide rating area, the average price paid is$11,085. While large and striking, these price differences are actually less extreme than the observed differences between commercial and Medicare inpatient prices in Massachusetts. Taken literally, my results imply that aggregating rating areas may be an effective means to curb health care provider market power.
The third chapter studies the effects of clinical outsourcing on quality of care. I identify more than 250 distinct events for which a hospital's emergency department transitions from being independent to being managed by one of two larger, national staffing companies. Using an event study regression framework, I find that the "treated" hospitals improve with respect to measures of thoroughness and timeliness of care. I also find an increased volume of patients admitted to the hospital from the ED. However, I am unable to detect statistically significant changes in clinical outcomes, such as readmission rates and mortality, nor am I able to detect changes in patient satisfaction. These results suggest that outsourcing of clinical hospital departments may lead to improved efficiency of care delivery; however, these benefits may not offset their negative effects, such as higher prices and higher rates of out-of-network billing. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.43874555826187134, "perplexity": 3219.4547960141463}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652662604495.84/warc/CC-MAIN-20220526065603-20220526095603-00208.warc.gz"} |
https://www.toktol.com/notes/context/3282/maths/surds/conjugate-surds | Use adaptive quiz-based learning to study this topic faster and more effectively.
# Conjugate surds
The conjugate of the sum of two surds $\sqrt{x}\Tred{+} \sqrt{y}$ is $\sqrt{x} \Torange{-} \sqrt{y}$. We just need to change sign.
The conjugate of $1\Tred{+}\sqrt{2}$ is $1\Torange{-}\sqrt{2}$.
The conjugate of $\sqrt{3}\Tred{-} \sqrt{5}$ is $\sqrt{3}\Torange{+}\sqrt{5}$.
Conjugate surds are useful because the product is simple
$$(\Tblue{\sqrt{x}+\sqrt{y}})(\Tgreen{\sqrt{x}-\sqrt{y}}) = (\sqrt{x})^2 - (\sqrt{y})^2 = x - y.$$
Division / reciprocal of conjugate surds simplifies as well
$$\frac{1}{\Tblue{\sqrt{x} - \sqrt{y}}} = \frac{\Tgreen{\sqrt{x}+\sqrt{y}}}{(\Tblue{\sqrt{x} - \sqrt{y}})(\Tgreen{\sqrt{x}+\sqrt{y}})} = \frac{\Tgreen{\sqrt{x} +\sqrt{y}}}{x-y}.$$
Here are a few examples
\begin{align*} (\Tblue{\sqrt{2}+\sqrt{3}})(\Tgreen{\sqrt{2}-\sqrt{3}}) &= 2 - 3 = -1\\ (\Tblue{\sqrt{5}-1})(\Tgreen{\sqrt{5}+1}) & = 5-1 = 4\\ \frac{1}{\Tblue{1+\sqrt{2}}} = \frac{\Tgreen{1-\sqrt{2}}}{1-2} &= -1+\sqrt{2}\\ \frac{3}{\Tblue{\sqrt{7}-1}} = \frac{3(\Tgreen{\sqrt{7}+1})}{7-1} &= \frac{\sqrt{7}+1}{2} \end{align*} | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9997745156288147, "perplexity": 2917.7196986007625}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-30/segments/1500549424154.4/warc/CC-MAIN-20170722222652-20170723002652-00482.warc.gz"} |
https://eldenelmanto.com/research-4/ | Papers
1. Thesis: Motivic Contractibility of the Space of Rational Maps (preliminary version, comments welcome, last updated April 28 2018) (To be split into two papers).
2. Motivic Landewber Exact Theories and Étale Cohomology (with Marc Levine, Markus Spitzweck and Paul Arne Østvær). [Arxiv:1711:06258] (preliminary version, comments welcome, last updated Nov 16 2017).
3. Motivic Infinite Loop Spaces (with Marc Hoyois, Adeel Khan, Vladimir Sosnilo and Maria Yakerson[Arxiv:1711:05248] (submitted, last updated: May 21 2018).
4. Modules over MW-Motivic Cohomology (with Håkon Andreas Kolderup) [Arxiv:1708.05651] (title to be revised and result generalized further, comments welcome, last updated: Aug 22 2017) .
5. A Primer to Unstable Motivic Homotopy Theory (with Benjamin Antieau). Surveys on Recent Developments in Algebraic Geometry, Proc. Sympos. Pure Math. 95 (2017), 305-370. [Arxiv:1605.00929].
6. Some nontrivial examples of the BOS twisted spectral sequence (with Igor Kriz). New York J. Math. 22 (2016) 363–378. [Arxiv:1604.04260] [NYJM].
Reports
1. Topological Periodic Cyclic Homology of Smooth $\mathbb{F}_p$-algebras. (After Bhatt-Morrow-Scholze) (submitted, Oberwolfach Report, last updated May 26 2018).
In Preparation
1. Twisted Homotopy $K$theory and Twisted Cycle Class Maps.
2. Étale Framed Motives.
3. Relative Étale Realization of motivic spaces. (with David Carchedi, available upon request).
4. The Motivic Dyer-Lashof algebra. (with Tom Bachmann and Jeremiah Heller).
5. Framed Transfers and Motivic Fundamental Classes. (with Marc Hoyois, Adeel Khan, Vladimir Sosnilo and Maria Yakerson). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 2, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.48277077078819275, "perplexity": 16047.419410391005}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-30/segments/1531676589029.26/warc/CC-MAIN-20180716002413-20180716022413-00393.warc.gz"} |
http://www.maa.org/publications/maa-reviews/a-functional-analysis-framework-for-modeling-estimation-and-control-in-science-and-engineering | # A Functional Analysis Framework for Modeling, Estimation and Control in Science and Engineering
###### H. T. Banks
Publisher:
Chapman & Hall/CRC
Publication Date:
2012
Number of Pages:
268
Format:
Hardcover
Price:
79.95
ISBN:
9781439880838
Category:
Textbook
We do not plan to review this book.
Introduction to Functional Analysis in Applications
Example 1: Heat Equation
Some Preliminaries: Hilbert, Banach, and Other Spaces Useful in Operator Theory
Return to Example 1: Heat Equation
Example 2: General Transport Equation
Example 3: Delay Systems–Insect/Insecticide Models
Example 4: Probability Measure Dependent Systems — Maxwell’s Equations
Example 5: Structured Population Models
Semigroups and Infinitesimal Generators
Basic Principles of Semigroups
Infinitesimal Generators
Generators
Introduction to Generation Theorems
Hille-Yosida Theorems
Results from the Hille-Yosida Proof
Corollaries to Hille-Yosida
Lumer-Phillips and Dissipative Operators
Examples Using Lumer-Phillips Theorem
Adjoint Operators and Dual Spaces
Adjoint Operators
Dual Spaces and Strong, Weak, and Weak* Topologies
Examples of Spaces and Their Duals
Return to Dissipativeness for General Banach Spaces
More on Adjoint Operators
Examples of Computing Adjoints
Gelfand Triple, Sesquilinear Forms, and Lax-Milgram
Example 6: The Cantilever Beam
The Beam Equation in the Form x derivative = Ax + F
Gelfand Triples
Sesquilinear Forms
Lax-Milgram (Bounded Form)
Lax-Milgram (Unbounded Form)
Summary Remarks and Motivation
Analytic Semigroups
Example 1: The Heat Equation (again)
Example 2: The Transport Equation (again)
Example 6: The Beam Equation (again)
Summary of Results on Analytic Semigroup Generation by Sesquilinear Forms
Tanabe Estimates (on "Regular Dissipative Operators")
Infinitesimal Generators in a General Banach Space
Abstract Cauchy Problems
General Second-Order Systems
Introduction to Second-Order Systems
Results for σ2 V-elliptic
Results for σ2 H-semielliptic
Stronger Assumptions for σ2
Weak Formulations for Second-Order Systems
Model Formulation
Discussion of the Model
Theorems 9.1 and 9.2: Proofs
Inverse or Parameter Estimation Problems
Approximation and Convergence
Some Further Remarks
"Weak" or "Variational Form"
Finite Element Approximations and the Trotter-Kato Theorems
Finite Elements
Trotter-Kato Approximation Theorem
Delay Systems: Linear and Nonlinear
Linear Delay Systems and Approximation
Modeling of Viral Delays in HIV Infection Dynamics
Nonlinear Delay Systems
State Approximation and Convergence for Nonlinear Delay Systems
Fixed Delays versus Distributed Delays
Weak* Convergence and the Prohorov Metric in Inverse Problems
Populations with Aggregate Data, Uncertainty, and PBM
A Prohorov Metric Framework for Inverse Problems
Metrics on Probability Spaces
Example 5: The Growth Rate Distribution Model and Inverse Problem in Marine Populations
The Prohorov Metric in Optimization and Optimal Design Problems
Two Player Min-Max Games with Uncertainty
Optimal Design Techniques
Generalized Curves and Relaxed Controls of Variational Theory
Preisach Hysteresis in Smart Materials
NPML and Mixing Distributions in Statistical Estimation
Control Theory for Distributed Parameter Systems
Motivation
Abstract Formulation
Infinite Dimensional LQR Control: Full State Feedback
The Finite Horizon Control Problem
The Infinite Horizon Control Problem
Families of Approximate Control Problems
The Finite Horizon Problem Approximate Control Gains
The Infinite Horizon Problem Approximate Control Gains
References
Index | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8745826482772827, "perplexity": 22408.89351111746}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-42/segments/1414119648146.28/warc/CC-MAIN-20141024030048-00061-ip-10-16-133-185.ec2.internal.warc.gz"} |
https://tomflaminio.wordpress.com/tag/coherence/ | IPMU 2018
My contribute paper titled “Logics for strict coherence and Carnap-regular probability functions” has been recently accepted to be presented at the 17th International Conference on Information Processing and Management of Uncertainty in Knowledge-Based Systems – IPMU 2018. that will take place in Cádiz, Spain.
Layers of zero probability and stable coherence over Łukasiewicz events
Tommaso Flaminio, Lluis Godo
The notion of stable coherence has been recently introduced to characterize coherent assignments to conditional many-valued events by means of hyperreal-valued states. In a nutshell, an assignment, or book, β on a finite set of conditional events is stably coherent if there exists a coherent variant β of β such that β maps all antecedents of conditional events to a strictly positive hyperreal number, and such that β and β differ by an infinitesimal. In this paper, we provide a characterization of stable coherence in terms of layers of zero probability for books on Łukasiewicz logic events.
Keywords: Layers of zero probability, Conditional probability, Stable coherence MV-algebras.
Volume 21, Issue 1, pp. 113–123.
On the complexity of Strictly Coherent Books
Given an book on formulas (i.e., a partial map on SL to rational numbers of [0,1]), deciding if it is coherent is an NP-complete problem. The proof essentially uses Carathéodory theorem which characterizes the points of a convex set: given a convex set C=cl-co(X) whose affine dimension is n, then x belongs to C if and only if there is a finite subset Y of X of cardinality at most n+1, such that x is a convex combination of the elements of Y. Indeed a book is coherent if and only if it belongs to cl-co(H) being H the set of logical valuations.
Moving from coherence to strict-coherence essentially boils down, in geometrical terms, to providing a characterization, á la Carathéodory, for the relative interior of cl-co(H). Steinitz theorem gives a (unfortunately useless) direction: if a point x belongs to relint cl-co(H), then there exists a finite subset K of H of cardinality at most 2n such that x belongs to relint cl-co(K). The converse direction (which is key for the decidability of a strictly coherent book) is trivially false: consider a cube C in R3 and pick a point x lying in the relint of a face of C. Then x belongs to the relative interior of a square, but not to the relint of the cube.
In the last weeks I’m just trying to extend (in certain sense) Steinitz theorem to obtain a characterization of the relative interior of a convex set. I don’t know if I will get it, but I like very much the drawings. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9178259372711182, "perplexity": 654.3937600122314}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-50/segments/1606141201836.36/warc/CC-MAIN-20201129153900-20201129183900-00706.warc.gz"} |
http://www.ntrand.com/laplace-distribution/ | // Home / Documentation / Gallery of Distributions / Laplace distribution
# Laplace distribution
## Shape of Distribution
### Basic Properties
• Two parameters $\mu, \phi$ are required.
$\phi>0$
• Continuous distribution defined on entire range
• This distribution is always symmetric.
### Probability
• Cumulative distribution function
$F(x)=\begin{cases}\frac{1}{2}\exp\left(\frac{x-\mu}{\phi}\right)\;&(x<\mu)\\1-\frac{1}{2}\exp\left(-\frac{x-\mu}{\phi}\right)\;&(x\geq \mu)\end{cases}[/latex]
• Probability density function
[latex]f(x)=\frac{1}{2\phi}\exp\left(-\frac{|x-\mu|}{\phi}\right)$
• How to compute these on Excel.
1
2
3
4
5
6
7
8
A B
Data Description
0.5 Value for which you want the distribution
8 Value of parameter Mu
2 Value of parameter Phi
=(A2-A3)/A4 Standardized variable z
Formula Description (Result)
=IF(A2<A3,0.5*EXP(A5),1-0.5*EXP(-A5)) Cumulative distribution function for the terms above
=0.5*EXP(-ABS(A5))/A4 Probability density function for the terms above
### Quantile
• Inverse function of cumulative distribution function
$F^{-1}(P)=\begin{cases}\phi\ln 2P+\mu\;&(P<0.5)\\-(\phi\ln 2(1-P)+\mu)\;&(P\geq 0.5)\end{cases}$
• How to compute this on Excel.
1
2
3
4
5
6
A B
Data Description
0.7 Probability associated with the distribution
1.7 Value of parameter Mu
0.9 Value of parameter Phi
Formula Description (Result)
=IF(P<0.5,A4*LN(2*A2)+A3,-(A4*LN(2*(1-A2))+A3)) Inverse of the cumulative distribution function for the terms above
## Characteristics
### Mean – Where is the “center” of the distribution? (Definition)
• Mean of the distribution is given as $\mu$.
### Standard Deviation – How wide does the distribution spread? (Definition)
• Variance of the distribution is given as
$2\phi^2$
Standard Deviation is a positive square root of Variance.
• How to compute this on Excel
1
2
3
4
A B
Data Description
2 Value of parameter Phi
Formula Description (Result)
=SQRT(2)*A2 Standard deviation of the distribution for the terms above
### Skewness – Which side is the distribution distorted into? (Definition)
• Skewness of the distribution is $0$.
### Kurtosis – Sharp or Dull, consequently Fat Tail or Thin Tail (Definition)
• Kurtosis of the distribution is $3$.
## Random Numbers
• Random number x is generated by inverse function method, which is for uniform random U,
$x=\begin{cases}\phi\ln 2U+\mu\;&(U<0.5)\\-(\phi\ln 2(1-U)+\mu)\;&(U\geq 0.5)\end{cases}$
• How to generate random numbers on Excel.
1
2
3
4
5
A B
Data Description
0.5 Value of parameter Mu
0.5 Value of parameter Phi
Formula Description (Result)
=IF(NTRAND(100)<0.5,A3*LN(2*NTRAND(100))+A2,-(A3*LN(2*(1-NTRAND(100)))+A2)) 100 Laplace deviates based on Mersenne-Twister algorithm for which the parameters above
Note The formula in the example must be entered as an array formula. After copying the example to a blank worksheet, select the range A5:A104 starting with the formula cell. Press F2, and then press CTRL+SHIFT+ENTER.
## NtRand Functions
Not supported yet | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 9, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8894959092140198, "perplexity": 5521.198060858821}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948520042.35/warc/CC-MAIN-20171212231544-20171213011544-00071.warc.gz"} |
http://www.nag.com/numeric/MB/manual64_24_1/html/G03/g03eff.html | Integer type: int32 int64 nag_int show int32 show int32 show int64 show int64 show nag_int show nag_int
Chapter Contents
Chapter Introduction
NAG Toolbox
# NAG Toolbox: nag_mv_cluster_kmeans (g03ef)
## Purpose
nag_mv_cluster_kmeans (g03ef) performs K$K$-means cluster analysis.
## Syntax
[cmeans, inc, nic, css, csw, ifail] = g03ef(x, isx, cmeans, 'n', n, 'm', m, 'nvar', nvar, 'k', k, 'wt', wt, 'maxit', maxit)
[cmeans, inc, nic, css, csw, ifail] = nag_mv_cluster_kmeans(x, isx, cmeans, 'n', n, 'm', m, 'nvar', nvar, 'k', k, 'wt', wt, 'maxit', maxit)
Note: the interface to this routine has changed since earlier releases of the toolbox:
Mark 22: n, k have been made optional
Mark 24: drop weight, wt optional
.
## Description
Given n$n$ objects with p$p$ variables measured on each object, xij${x}_{\mathit{i}\mathit{j}}$, for i = 1,2,,n$\mathit{i}=1,2,\dots ,n$ and j = 1,2,,p$\mathit{j}=1,2,\dots ,p$, nag_mv_cluster_kmeans (g03ef) allocates each object to one of K$K$ groups or clusters to minimize the within-cluster sum of squares:
K p ∑ ∑i ∈ Sk ∑ (xij − xkj)2, k = 1 j = 1
$∑k=1K∑i∈Sk∑j=1p (xij-x-kj) 2,$
where Sk${S}_{k}$ is the set of objects in the k$k$th cluster and xkj${\stackrel{-}{x}}_{kj}$ is the mean for the variable j$j$ over cluster k$k$. This is often known as K$K$-means clustering.
In addition to the data matrix, a K$K$ by p$p$ matrix giving the initial cluster centres for the K$K$ clusters is required. The objects are then initially allocated to the cluster with the nearest cluster mean. Given the initial allocation, the procedure is to iteratively search for the K$K$-partition with locally optimal within-cluster sum of squares by moving points from one cluster to another.
Optionally, weights for each object, wi${w}_{i}$, can be used so that the clustering is based on within-cluster weighted sums of squares:
K p ∑ ∑i ∈ Sk ∑ wi(xij − x̃kj)2, k = 1 j = 1
$∑k=1K∑i∈Sk∑j=1pwi (xij-x~kj) 2,$
where kj${\stackrel{~}{x}}_{kj}$ is the weighted mean for variable j$j$ over cluster k$k$.
The function is based on the algorithm of Hartigan and Wong (1979).
## References
Everitt B S (1974) Cluster Analysis Heinemann
Hartigan J A and Wong M A (1979) Algorithm AS 136: A K-means clustering algorithm Appl. Statist. 28 100–108
Kendall M G and Stuart A (1976) The Advanced Theory of Statistics (Volume 3) (3rd Edition) Griffin
Krzanowski W J (1990) Principles of Multivariate Analysis Oxford University Press
## Parameters
### Compulsory Input Parameters
1: x(ldx,m) – double array
ldx, the first dimension of the array, must satisfy the constraint ldxn$\mathit{ldx}\ge {\mathbf{n}}$.
x(i,j)${\mathbf{x}}\left(\mathit{i},\mathit{j}\right)$ must contain the value of the j$\mathit{j}$th variable for the i$\mathit{i}$th object, for i = 1,2,,n$\mathit{i}=1,2,\dots ,n$ and j = 1,2,,m$\mathit{j}=1,2,\dots ,{\mathbf{m}}$.
2: isx(m) – int64int32nag_int array
m, the dimension of the array, must satisfy the constraint ${\mathbf{m}}\ge {\mathbf{nvar}}$.
isx(j)${\mathbf{isx}}\left(\mathit{j}\right)$ indicates whether or not the j$\mathit{j}$th variable is to be included in the analysis. If isx(j) > 0${\mathbf{isx}}\left(\mathit{j}\right)>0$, the variable contained in the j$\mathit{j}$th column of x is included, for j = 1,2,,m$\mathit{j}=1,2,\dots ,{\mathbf{m}}$.
Constraint: isx(j) > 0${\mathbf{isx}}\left(j\right)>0$ for nvar values of j$j$.
3: cmeans(ldc,nvar) – double array
ldc, the first dimension of the array, must satisfy the constraint ldck$\mathit{ldc}\ge {\mathbf{k}}$.
cmeans(i,j)${\mathbf{cmeans}}\left(\mathit{i},\mathit{j}\right)$ must contain the value of the j$\mathit{j}$th variable for the i$\mathit{i}$th initial cluster centre, for i = 1,2,,K$\mathit{i}=1,2,\dots ,K$ and j = 1,2,,p$\mathit{j}=1,2,\dots ,p$.
### Optional Input Parameters
1: n – int64int32nag_int scalar
Default: The first dimension of the array x.
n$n$, the number of objects.
Constraint: n > 1${\mathbf{n}}>1$.
2: m – int64int32nag_int scalar
Default: The dimension of the array isx and the second dimension of the array x. (An error is raised if these dimensions are not equal.)
The total number of variables in array x.
Constraint: ${\mathbf{m}}\ge {\mathbf{nvar}}$.
3: nvar – int64int32nag_int scalar
Default: The second dimension of the array cmeans.
p$p$, the number of variables included in the sums of squares calculations.
Constraint: 1nvarm$1\le {\mathbf{nvar}}\le {\mathbf{m}}$.
4: k – int64int32nag_int scalar
Default: The first dimension of the array cmeans.
K$K$, the number of clusters.
Constraint: k2${\mathbf{k}}\ge 2$.
5: wt( : $:$) – double array
Note: the dimension of the array wt must be at least n${\mathbf{n}}$ if weight = 'W'$\mathit{weight}=\text{'W'}$, and at least 1$1$ otherwise.
If weight = 'W'$\mathit{weight}=\text{'W'}$, the first n$n$ elements of wt must contain the weights to be used.
If wt(i) = 0.0${\mathbf{wt}}\left(i\right)=0.0$, the i$i$th observation is not included in the analysis. The effective number of observation is the sum of the weights.
If weight = 'U'$\mathit{weight}=\text{'U'}$, wt is not referenced and the effective number of observations is n$n$.
Constraint: if weight = 'W'$\mathit{weight}=\text{'W'}$, wt(i)0.0${\mathbf{wt}}\left(\mathit{i}\right)\ge 0.0$ and wt(i) > 0.0${\mathbf{wt}}\left(\mathit{i}\right)>0.0$ for at least two values of i$\mathit{i}$, for i = 1,2,,n$\mathit{i}=1,2,\dots ,n$.
6: maxit – int64int32nag_int scalar
The maximum number of iterations allowed in the analysis.
Default: 10$10$
Constraint: maxit > 0${\mathbf{maxit}}>0$.
### Input Parameters Omitted from the MATLAB Interface
weight ldx ldc iwk wk
### Output Parameters
1: cmeans(ldc,nvar) – double array
ldck$\mathit{ldc}\ge {\mathbf{k}}$.
cmeans(i,j)${\mathbf{cmeans}}\left(\mathit{i},\mathit{j}\right)$ contains the value of the j$\mathit{j}$th variable for the i$\mathit{i}$th computed cluster centre, for i = 1,2,,K$\mathit{i}=1,2,\dots ,K$ and j = 1,2,,p$\mathit{j}=1,2,\dots ,p$.
2: inc(n) – int64int32nag_int array
inc(i)${\mathbf{inc}}\left(\mathit{i}\right)$ contains the cluster to which the i$\mathit{i}$th object has been allocated, for i = 1,2,,n$\mathit{i}=1,2,\dots ,n$.
3: nic(k) – int64int32nag_int array
nic(i)${\mathbf{nic}}\left(\mathit{i}\right)$ contains the number of objects in the i$\mathit{i}$th cluster, for i = 1,2,,K$\mathit{i}=1,2,\dots ,K$.
4: css(k) – double array
css(i)${\mathbf{css}}\left(\mathit{i}\right)$ contains the within-cluster (weighted) sum of squares of the i$\mathit{i}$th cluster, for i = 1,2,,K$\mathit{i}=1,2,\dots ,K$.
5: csw(k) – double array
csw(i)${\mathbf{csw}}\left(\mathit{i}\right)$ contains the within-cluster sum of weights of the i$\mathit{i}$th cluster, for i = 1,2,,K$\mathit{i}=1,2,\dots ,K$. If weight = 'U'$\mathit{weight}=\text{'U'}$, the sum of weights is the number of objects in the cluster.
6: ifail – int64int32nag_int scalar
${\mathrm{ifail}}={\mathbf{0}}$ unless the function detects an error (see [Error Indicators and Warnings]).
## Error Indicators and Warnings
Errors or warnings detected by the function:
ifail = 1${\mathbf{ifail}}=1$
On entry, weight ≠ 'W'$\mathit{weight}\ne \text{'W'}$ or 'U'$\text{'U'}$, or n < 2${\mathbf{n}}<2$, or nvar < 1${\mathbf{nvar}}<1$, or ${\mathbf{m}}<{\mathbf{nvar}}$, or k < 2${\mathbf{k}}<2$, or ldx < n$\mathit{ldx}<{\mathbf{n}}$, or ldc < k$\mathit{ldc}<{\mathbf{k}}$, or maxit ≤ 0${\mathbf{maxit}}\le 0$.
ifail = 2${\mathbf{ifail}}=2$
On entry, weight = 'W'$\mathit{weight}=\text{'W'}$ and a value of wt(i) < 0.0${\mathbf{wt}}\left(i\right)<0.0$ for some i$i$, or weight = 'W'$\mathit{weight}=\text{'W'}$ and wt(i) = 0.0${\mathbf{wt}}\left(i\right)=0.0$ for all or all but one values of i$i$.
ifail = 3${\mathbf{ifail}}=3$
On entry, the number of positive values in isx does not equal nvar.
ifail = 4${\mathbf{ifail}}=4$
On entry, at least one cluster is empty after the initial assignment. Try a different set of initial cluster centres in cmeans and also consider decreasing the value of k. The empty clusters may be found by examining the values in nic.
ifail = 5${\mathbf{ifail}}=5$
Convergence has not been achieved within the maximum number of iterations given by maxit. Try increasing maxit and, if possible, use the returned values in cmeans as the initial cluster centres.
## Accuracy
nag_mv_cluster_kmeans (g03ef) produces clusters that are locally optimal; the within-cluster sum of squares may not be decreased by transferring a point from one cluster to another, but different partitions may have the same or smaller within-cluster sum of squares.
The time per iteration is approximately proportional to npK$\mathit{np}K$.
## Example
```function nag_mv_cluster_kmeans_example
x = [77.3, 13, 9.7, 1.5, 6.4;
82.5, 10, 7.5, 1.5, 6.5;
66.9, 20.6, 12.5, 2.3, 7;
47.2, 33.8, 19, 2.8, 5.8;
65.3, 20.5, 14.2, 1.9, 6.9;
83.3, 10, 6.7, 2.2, 7;
81.6, 12.7, 5.7, 2.9, 6.7;
47.8, 36.5, 15.7, 2.3, 7.2;
48.6, 37.1, 14.3, 2.1, 7.2;
61.6, 25.5, 12.9, 1.9, 7.3;
58.6, 26.5, 14.9, 2.4, 6.7;
69.3, 22.3, 8.4, 4, 7;
61.8, 30.8, 7.4, 2.7, 6.4;
67.7, 25.3, 7, 4.8, 7.3;
57.2, 31.2, 11.6, 2.4, 6.5;
67.2, 22.7, 10.1, 3.3, 6.2;
59.2, 31.2, 9.6, 2.4, 6;
80.2, 13.2, 6.6, 2, 5.8;
82.2, 11.1, 6.7, 2.2, 7.2;
69.7, 20.7, 9.6, 3.1, 5.9];
isx = [int64(1);1;1;1;1];
cmeans = [82.5, 10, 7.5, 1.5, 6.5;
47.8, 36.5, 15.7, 2.3, 7.2;
67.2, 22.7, 10.1, 3.3, 6.2];
[cmeansOut, inc, nic, css, csw, ifail] = nag_mv_cluster_kmeans(x, isx, cmeans)
```
```
cmeansOut =
81.1833 11.6667 7.1500 2.0500 6.6000
47.8667 35.8000 16.3333 2.4000 6.7333
64.0455 25.2091 10.7455 2.8364 6.6545
inc =
1
1
3
2
3
1
1
2
2
3
3
3
3
3
3
3
3
1
1
3
nic =
6
3
11
css =
46.5717
20.3800
468.8964
csw =
6
3
11
ifail =
0
```
```function g03ef_example
x = [77.3, 13, 9.7, 1.5, 6.4;
82.5, 10, 7.5, 1.5, 6.5;
66.9, 20.6, 12.5, 2.3, 7;
47.2, 33.8, 19, 2.8, 5.8;
65.3, 20.5, 14.2, 1.9, 6.9;
83.3, 10, 6.7, 2.2, 7;
81.6, 12.7, 5.7, 2.9, 6.7;
47.8, 36.5, 15.7, 2.3, 7.2;
48.6, 37.1, 14.3, 2.1, 7.2;
61.6, 25.5, 12.9, 1.9, 7.3;
58.6, 26.5, 14.9, 2.4, 6.7;
69.3, 22.3, 8.4, 4, 7;
61.8, 30.8, 7.4, 2.7, 6.4;
67.7, 25.3, 7, 4.8, 7.3;
57.2, 31.2, 11.6, 2.4, 6.5;
67.2, 22.7, 10.1, 3.3, 6.2;
59.2, 31.2, 9.6, 2.4, 6;
80.2, 13.2, 6.6, 2, 5.8;
82.2, 11.1, 6.7, 2.2, 7.2;
69.7, 20.7, 9.6, 3.1, 5.9];
isx = [int64(1);1;1;1;1];
cmeans = [82.5, 10, 7.5, 1.5, 6.5;
47.8, 36.5, 15.7, 2.3, 7.2;
67.2, 22.7, 10.1, 3.3, 6.2];
[cmeansOut, inc, nic, css, csw, ifail] = g03ef(x, isx, cmeans)
```
```
cmeansOut =
81.1833 11.6667 7.1500 2.0500 6.6000
47.8667 35.8000 16.3333 2.4000 6.7333
64.0455 25.2091 10.7455 2.8364 6.6545
inc =
1
1
3
2
3
1
1
2
2
3
3
3
3
3
3
3
3
1
1
3
nic =
6
3
11
css =
46.5717
20.3800
468.8964
csw =
6
3
11
ifail =
0
``` | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 108, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9048513770103455, "perplexity": 6647.6308558498085}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657137190.70/warc/CC-MAIN-20140914011217-00184-ip-10-234-18-248.ec2.internal.warc.gz"} |
https://mathzsolution.com/extending-the-result-%E2%88%AB%E2%88%9E01%E2%88%922cx21%E2%88%922sx2dx4%CF%80int_0infty-left-1-2cx2-1-2sx2-right-dx-frac4pi/ | # Extending the result ∫∞0((1−2C(x))2+(1−2S(x))2)dx=4π\int_{0}^{\infty} \left( ( 1 – 2C(x))^{2} + (1-2S(x))^{2} \right) \, dx = \frac{4}{\pi}
While generalizing this result, I succeeded in proving that for $\alpha > 0$, $\beta < 1$ and $1 < 2\alpha + \beta < 3$, we have
My question is
1. Is this a known result?
2. My ultimate goal is to examine whether the integral
has closed from or not for general $\alpha$ and $\beta$. I know that
but I know nothing for the other cases. (Here, the former identity in $(1)$ corresponds to the motivating problem linked above.) Is there any other known result concerning this integral?
A further inspection showed that
where
are Fresnel integrals. Indeed, this corresponds to
Note that major inverse symbolic calculators do not yield this result.
Pardon My Progress...
First, the sum of squared integrals inside the brackets, which for convenience we shall denote by $f{\left(x;\alpha\right)}$, may be rewritten as a single double integral with a little algebra and trigonometry:
Next, we apply a sequence of two two-variable transformations to put the integral into a more tractable form. The first substitution is a simple scaling transformation, $(1)$$(t_{1},t_{2})=(xu_{1},xu_{2})$; the second substitution is the more complicated transformation, $(2)$ $(u_{1}-u_{2},u_{1}u_{2})=(w_{1},w_{2})$:
To perform the integration with respect to $w_{2}$, I appeal to Gradshteyn 3.197(2): under the conditions $|\arg{\frac{u}{\beta}}|<\pi\lor |\frac{\beta}{u}|<1$, and $0<\Re{\left(\mu\right)}<\Re{\left(\lambda-\nu\right)}$, we have the result,
Let $\mu=1$, $\nu=-\frac12$, $\lambda=\alpha$, $u=1+w_{1}$, and $\beta=\frac14w_{1}^2$. Then for $\frac12<\Re{\left(\alpha\right)}<1\land w_{1}>0$,
The hypergeometric function above quite conveniently reduces to a rational function for the specified combination of parameters: for $\alpha\neq1$,
Thus, for $\frac12<\Re{\left(\alpha\right)}<1\land w_{1}>0$,
and hence:
where in the third line we've made the substitution $w_{1}=y$ for the sake of eliminating the dependency on subscripted variables, and where in the last line we've introduced the auxiliary function $g{\left(y;\alpha\right)}$ simply for the sake conveniently denoting the function,
Now if we repeat our initial trick of rewriting the square of an integral as a double integral, we can arrive at an expression for $\mathcal{I}{\left(\alpha,\beta\right)}$ as an ordinary triple integral:
Change the order of integration so that the integration over $x$ is first:
Then the inner integral with respect to $x$ may be evaluated in closed form with an appeal to another result from Gradshteyn. Proposition 3.762(3) of Gradshteyn states that, given $a,b\in\mathbb{R}$ and $\mu\in\mathbb{C}$ such that $a>0,~b>0$, and $0<\Re{(\mu)}<1$, then the following improper integral has the closed form:
Setting $(a,b,\mu)\mapsto(y,z,4(1-\alpha)-\beta+1)$ in the above proposition yields the following corrollary: given $y,z\in\mathbb{R}$ and $p\in\mathbb{C}$ such that $y>0,~z>0$, and $-1<\Re{\left(4(1-\alpha)-\beta\right)}<0$, then the following improper integral has the closed form,
Thus, we may reduce our integral representation of $\mathcal{I}{\left(\alpha,\beta\right)}$ to a single double integral:
Update:
Now we'll focus on reducing the previously defined function $\tilde{\mathcal{I}}{\left(\alpha,\beta\right)}$. First of all, by symmetry we can reduce the region of integration to one where the absolute value bars are no longer necessary inside the integrand, which will obviate some of tedium of evaluation:
Next, we rescale the interval of integration of the inner integral to the unit interval via the substitution $z=y\,\omega$:
At this stage, the inner integral over $\omega$ may be evaluated in terms of the Appell hypergeometric function, $F_{1}$. | {"extraction_info": {"found_math": true, "script_math_tex": 41, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 11, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9831788539886475, "perplexity": 567.6149316517897}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764499801.40/warc/CC-MAIN-20230130034805-20230130064805-00149.warc.gz"} |
https://cob.silverchair.com/jeb/search-results?qb=%7B%22Keywords1%22:%22anion+exchange%22%7D | 1-7 of 7
Keywords: anion exchange
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Journal Articles
J Exp Biol (2020) 223 (12): jeb216895.
Published: 15 June 2020
...). M, mucosal; S, serosal. Fig. 1. The intestine of marine teleost fish is proposed to be a major pathway for eliminating oxalate (Ox 2− ). This occurs in association with epithelial bicarbonate (HCO 3 − ) secretion, possibly involving Slc26-mediated anion exchange, and intraluminal calcium...
Journal Articles
J Exp Biol (2010) 213 (3): 459–468.
Published: 1 February 2010
... anion exchange SLC4 water absorption carbonic anhydrase acid–base balance During the last decade, intestinal HCO 3 – secretion via apical Cl – /HCO 3 – exchange has become recognized as an important component in the processing of seawater ingested to meet the osmoregulatory needs...
Journal Articles
J Exp Biol (2009) 212 (23): 3873–3881.
Published: 1 December 2009
.... , Laurent P. , Pärt P. , Walsh P. J. ( 1998 ). Nitrogen excretion and the cardiorespiratory physiology of the gulf toadfish, Opsanus beta . Physiol. Zool. 71 , 492 - 505 . Grosell M. ( 2006 ). Intestinal anion exchange in marine fish osmoregulation . J. Exp. Biol. 209...
Journal Articles
J Exp Biol (2007) 210 (19): 3484–3493.
Published: 1 October 2007
... suggest the presence of an anion exchange mechanism exchanging monovalent for polyvalent anions. Polyvalent inorganic anions(SO 4 2– and PO 4 3– ) are known to associate with metals inside vesicles and a detoxification model is presented that suggests how these anions may contribute to concretion...
Journal Articles
J Exp Biol (2002) 205 (18): 2943–2954.
Published: 15 September 2002
... are equipped with various pathways to secrete protons, and that the anion exchange activity especially of pseudobranch cells appears to be different from that in gills. References Barnett, C. H. ( 1951 ). The structure and function of the choroidal gland of teleostean fish. J. Anat. 85 , 113 -119...
Journal Articles
J Exp Biol (2002) 205 (8): 1069–1075.
Published: 15 April 2002
.... Incubation of gas gland cells with 4,4′-diisothiocyanostilbene-2,2′-disulphonic acid(DIDS), an inhibitor of anion exchange, also caused a decrease in pHi, but this decrease was not as pronounced as in the presence of MIA. Furthermore, at low pHi, the effect of DIDS was further reduced, suggesting...
Journal Articles
J Exp Biol (1991) 156 (1): 41–61.
Published: 1 March 1991
... preloaded with acetate or bicarbonate was enhanced compared to [ 3 H]acetate uptake into vesicles preloaded with gluconate. A series of trans-stimulation and cis-inhibition studies involving both organic and inorganic anions indicated the presence of a highly specific anion-exchange carrier which readily... | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8781751990318298, "perplexity": 25947.245350216555}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-49/segments/1669446710764.12/warc/CC-MAIN-20221130124353-20221130154353-00128.warc.gz"} |
https://rejectingrationality.org/blog/tags/philosophy/ | ## Stop Calling Subjects Ethically Fraught
### It's An Excuse Not An Argument
Listening to the Last Week Tonight on Gene Editing (it’s pretty good) and seeing this debate about paying organ donors I’m compelled to call out the practice of simply asserting that something is ethically fraught or troublesome.
Both with respect to not compensating organ donors (something which could save huge numbers of lives) and with (mostly prospective) limits on eliminating genetic disease or even barring improvement I think we let people who are simply uncomfortable with change off the hook by constantly repeating the supposed truism that the issue is ethically fraught or there are serious ethical concerns. It’s basically a free pass that excuses the fact that they are putting their discomfort ahead of people’s welfare.
Under all the scenarios/conditions seriously being considered No, there aren’t ethical concerns. Fears like letting a bank reposes your kidney are no more relevant to the proposals on the table than the fear that debtors will enslave people is to wages. Similarly, concerns about racially motivated eugenics programs have no plausible relationship to any kind of gene therapy even being prospectively considered.
Of course, we should hear potential concerns about such policies just like we would for any other policy/technology. However, opponents should be on the spot to either shut up or come up with compelling arguments suggesting harms. Based on the fact that the opponent in the WSJ to paying for organ donation is reduced to arguments like “The introduction of money for a precious good comes at the cost of the ability for one to aspire to virtue” makes me doubt they can come up with such arguments.
I’d add that I think philosophers are partially to blame on this point. As a matter of philosophical interest we correctly find clever new arguments seeking to show that paid organ donation is actually somehow problematically coercive or otherwise wrong more interesting than the obvious argument that it saves lives. However, just as physicists need to convey to the public that the very thing which makes theories which deviate from the standard model interesting also makes them less likely I think philosophers need to do this as well.
#### How to Provide Better Incentives to Organ Donors
Three experts discuss strategies to address the shortage of organs available for people who need transplants.
## Sleeping Beauty and Philosophy of Language
### Why The Debate Over The Sleeping Beauty Paradox Is Confused
The Sleeping Beauty Problem is a famous philosophical problem in the philosophy of probability which has seeped into debates in the rationalist community. Apart from it’s independent philosophical interest it raises issues of practical significance via it’s close connection to the Doomsday argument. However, I will argue below that sleeping beauty is only an apparent problem that arises only because framing the talk in terms of probability hides an unjustified assumption that our notion of (epistemically justified) credence refers and we have a good grip on what it refers to. An assumption which this very paradox shows to be false. As a result all attempts to directly argue for any particular position on the sleeping beauty problem is deeply confused.
In particular, if we take our word credence to (like water) refer to something like the most scientifically/philosophically useful term in the area then it should be obvious that the only answer we can give is “we don’t know.” If not then our natural language term simply doesn’t uniquely refer so it doesn’t make sense to expect a right answer to the sleeping beauty problem (though each particular preciseification would yield one).
In a latter post I’ll argue that debates about interpretations of probability are making a similar error in assuming there are the sort of facts behind the meaning of ascriptions of probability that are at issue between the interpretations.
#### The Sleeping Beauty Problem
The Sleeping Beauty Problem is defined thusly on wikipedia
Sleeping Beauty volunteers to undergo the following experiment and is told all of the following details: On Sunday she will be put to sleep. Once or twice, during the experiment, Beauty will be awakened, interviewed, and put back to sleep with an amnesia-inducing drug that makes her forget that awakening. A fair coin will be tossed to determine which experimental procedure to undertake:
1. If the coin comes up heads, Beauty will be awakened and interviewed on Monday only.
2. If the coin comes up tails, she will be awakened and interviewed on Monday and Tuesday.
In either case, she will be awakened on Wednesday without interview and the experiment ends. Any time Sleeping Beauty is awakened and interviewed she will not be able to tell which day it is or whether she has been awakened before.
During the interview Beauty is asked: “What is your probability now for the proposition that the coin landed heads?”.
The apparent paradox arises because there are compelling seeming arguments (described in more detail on wikipedia) that sleeping beauty should answer 1/2 and a 1/3. Roughly the argument for 1/2 is that on waking up sleeping beauty doesn’t receive any information that might justify updating her probability. An argument for 1/3 is that when woken up she should assign equal probability to it being Monday or Tuesday conditional on the coin landing tails while conditional on the day being Monday she should assign equal probability to the coin being heads or tails. As there are twice as many equally probable outcomes involving tails the probability the coin landed heads is 1/3 (this is also the probability that sleeping beauty should use to bet with if offered a bet each time she is woken).
While phrased in this manner the sleeping beauty problem seems like a pretty irrelevant paradox the same reasoning applies in much more interesting settings. For instance, suppose you assign some non-zero prior to the possibility that instead of one single universe there are infinitely many universes containing an exact duplicate of you1. If you accept the arguments for the 1/3 position in the sleeping beauty paradox the mere fact that you are having an experience should cause you to update your probability for there being infinitely many universes to 1.
Similarly, what arguments you find compelling in the sleeping beauty case affect how you should evaluate the Doomsday argument. For instance, taking the 1/3 position in sleeping beauty might lead one to argue against the doomsday argument on the grounds that there are more total individuals having experiences if there is no imminent doomsday and this should weight our probabilities.
#### What Does A Credence Mean?
While the sleeping beauty paradox may pose a challenge to our philosophical idea of (subjective) probability it doesn’t raise any problems for the mathematics of probability. But if the problem isn’t mathematical what is it about? At first blush it appears to be a question about the notion of (epistemically appropriate) credence. In other words sleeping beauty is a question about epistemology dressed up as a problem about probability.
But once we realize this we should be immediately be drive to ask: what does it mean to have an (epistemically appropriate) credence of 1/3 (or half)?
The sleeping beauty paradox itself demonstrates immediately that there are multiple plausible ways we could understand such a statement. For instance, one way of understanding the notion of epistemically appropriate credence might build from the intuition that the percent of times you believe something to be true with credence p and it is true should be p. If you allow the fanciful device of imagining restarting the universe one might think that a credence p in a claim C is appropriate relative to a given experience E if we ran reality a bunch of times and the ratio of the number of times C is true when E is experienced approaches p. In other words a credence is like a bet with reality you take each time you form it (though one would need to flesh out the notion of forming a credence if one wanted to pursue this). This concept supports the 1/3 answer to the sleeping beauty problem since, if the experiment is repeated many times, 1/3 of the times sleeping beauty has the experience of waking up the coin will be heads.
On the other hand, another way of understanding the notion of epistemically appropriate credence might build from the idea that you only care about whether or not a claim is true not how often it is true relative to the number of times you form a credence about it. In other words, credence p in a claim C is appropriate relative to a given experience E is appropriate if the number of times the universe is restarted where both claim C is true and you (or someone?) has experience E divided by the number of times the universe is restarted and you have experience E approaches p. This concept supports the 1/2 answer to the sleeping beauty problem since if the experiment is repeated many times 1/2 of those times will result in the coin landing heads.
Now, of course, all the problems with defining interpretations of probability and limiting frequency approaches mean I didn’t fully define a precise concept in either case. However, I don’t need to fully define any concept merely demonstrate that there is more than one way one could want to define the notion of epistemically appropriate credence.
Which notion one is interested in will depend on the particular situation at hand. For instance, if sleeping beauty’s concern is about making a bet with one of the researchers (who promises to accept bets either day) she should use the concept which considers the number of times she’s had the experience. If one of the researchers is a serial killer who tells her right before she goes under that he’s going to kill her spouse if the coin lands heads then a notion of credence which doesn’t concern herself with how many times she has the experience. Note that this nicely resolves the more applied versions of sleeping beauty once we make clear just what we are interested in.
Given that there are more than one notion of epistemically appropriate credence one could care about the most informative to the sleeping beauty problem should simply be that it is under-specified. Indeed, the fact that for any practical purpose we know which value to use should have been a red flag from the beginning that this was merely a verbal dispute not a genuine puzzle about epistemology.
#### Philosophy of Language Discussion
While I expect that I could stop at this point and satisfy non-philosophers there is a tendency among philosophers to insist that even if we don’t know exactly what properties epistemically appropriate credence (or ‘probability’) has one might nevertheless be justified in believing it uniquely asserts. While I’m skeptical of such claims in this case it certainly can happen. For instance, ‘water’ referred to H2O when Avogadro determined water’s chemical formula rather than changing it’s meaning2. However, that was only because (and to the extent) that past dispositions about the use of the word water would have lead (at least hypothetically philosophically informed3) people to hesitate to call something water despite it’s appearances if given sufficient reason to suspect it might differ in underlying nature, e.g., if flown in a spaceship to visit a stream on another world people would have expressed uncertainty as to whether the refreshing clear liquid was water.
But if our term ‘probability’ (or ‘epistemically appropriate credences’) is to, like ‘water’, refer to whatever natural kind fits sufficiently well with our usage then the only sane position for philosophers to take on questions like sleeping beauty is to admit that they don’t know, and indeed can’t know, until we figure out what natural kinds are in the neighborhood of our use of the term. After all, there is no doubt that problems like the sleeping beauty paradox differ from our usual applications of epistemically appropriate credences in ways that might or might not affect how some, yet undiscovered, natural kind in the neighborhood might apply. This wouldn’t reveal any kind of deep puzzle about the nature of the world, merely uncertainty as to the true reference of ‘epistemically appropriate credences’ as a result of our lack of knowledge about natural kinds in the neighborhood.
So sure, we can take ‘epistemically appropriate credences’ to refer to whatever concept turns out to be most elegantly useful in our theorizing about uncertainty in the world. However, if we do then the answer to all these paradoxes about probability becomes a simple “I don’t know” for the boring reason that we don’t know if there is an elegantly useful concept in the neighborhood yet. Thus, bald insistence that our notion of epistemically appropriate credences or probability has an implicit forward reference to the best concept in the neighborhood can’t save the arguments between the 1/2 and 1/3 camps from being appropriately regarded as confused.
1. To make the case fully analogous, one may assume that you have a soul which occupies each duplicate of you in turn, so you can’t escape the conclusion merely by appeal to the fact the same individual isn’t having the experiences.
2. While this makes for a nice philosophical parable I’m not totally convinced the claim holds up as a matter of linguistic history. The latin word aqua seems to be closely linked in meaning to the stuff in rivers and streams so I wouldn’t take it for granted that the average English speaker didn’t just mean whatever flows in the rivers and streams by ‘water’ back in 1811.
3. It might not be necessary for this to be the usual reaction but surely we must imagine that hypothetical philosophers who were somehow well versed Kripke’s arguments in Naming and Necessity back in 1800 would have such doubts if they didn’t understand ‘water’ to mean (as it is surely possible for a word to mean) any wet, clear, refreshing stuff that flows in a river or stream. If you deny this then you aren’t really studying the observable phenomena of language anymore but positing some kind of inaccessible platonic realm of truths regarding true meanings completely beyond the grasp of those using the language.
## Legalizing Baby Sales
### Don't We Want More Happy Parents, Healthier Pregnancies and Genetically Advantaged Children?
Julia Galef has more from her wonderful unpopular ideas series. This one covers unpopular ideas about children and reproduction. There’s a lot of interesting ideas in there but the one I found most appealing, though unfortunately pretty unlikely to be adopted, was the suggestion that we should allow parents to ‘sell’ their newborns.
There are some obvious problems with allowing people to do this in the third world. In traditional subsistence farming contexts children may offer a net economic gain to a family particularly if given only minimal accommodations. No one wants to return to the halcyon days when we hired children out as indentured servants where unsympathetic farmers would raise’ them in Dickensian conditions. However, in the developed world even the most neglected child is still a net economic cost so we can safely assume no one will be buying children to have someone they can extract work from without the guilt of mistreating their own offspring.
Such a policy would help many loving couples find children to adopt and I even believe there is a real benefit to removing children from the care of anyone so uninterested in them (or convinced they are unfit) that they are willing to make such a sale1.
But won’t this just result in drug addicts and other unfit parents popping out babies left and right for a bit of cash? Well maybe some college profs with oxy addictions might but babies to fund their habit but those babies would be in demand from parents who will offer them a good home (and unlike alcohol there is no analogous fetal opiate, meth or even crack syndrome). However, I suspect (but haven’t been able to find statistics on this) that the children born to street addicts already have plenty of problems finding adoptive parents. Moreover, pregnancy is a long, difficult process that its safe to assume anyone who finds it worthwhile to grow babies for sale is offering a high-value baby (good genes and health) who will be placed in a comfortable living situation.
What about the idea that it would incentivize women to choose the couple willing to pay the most for the child rather than the best family? First, I’m skeptical of the ability of birth mothers, given the lack of truly extensive interactions and their limited control over the process have any particular ability to pick good parents. Indeed, I suspect that the ability and willingness of the adopting family to pay would actually be a better indicator of the child’s future welfare than any gut level instinct. Second, when a birth mother decides between two potential families wanting to adopt the families who weren’t selected presumably still go on to adopt someone making this whole matter a wash from a social welfare perspective.
Basically, selling babies isn’t really any different than the surrogacy arrangements we are already comfortable allowing except that it no longer incentivizes people to only pretend to be willing to give the child up or to squeeze more money from the deal with a last minute change of heart. Where surrogacy arrangements incentivize the pregnant woman to divert money intended to increase the child’s health to their own pockets baby sales incentivize offering documented high quality care to maximize sale value.
Really, the only downside I can really see is just how obvious it will make our racial preferences in children. White babies will be worth way more than black ones.
1. In developed countries there is little reason to fear that more people would be extorted to sell their children if the practiced was legalized. One might imagine that in war torn parts of the world a market in children would give warlords the bright idea of forcing women to sell their children and give them the money. In the first world the only pressure on a woman to sell is the crappy circumstances she would be in whether or not baby sales were legal and if that induces her to make a sale I suspect everyone will be better off as a result, particularly the child.
## What Does It Mean To Assign Babies A Gender?
### More Philosophical Difficulties With The Concept Of Gender
I’m posting this because I think it raises some interesting philosophical issues about what it even means to assign a child a gender at birth as opposed to merely assigning them a sex. I mean surely the article isn’t advocating that we stop observing which genitalia a child has at birth or even that we stop using those facts to make decisions1. So then what even does it consist of to assign a child a gender at birth?
It seems to have something to do with assuming they will fill a certain kind of societal role, i.e., will comply with the societal expectations we have for men or women. So, for example, merely having a doctor note the genitalia expressed by the child or passing that information on to others wouldn’t count but having a “It’s a boy” party, and thereby encouraging guests to give boy appropriate presents, would.
However, this raises interesting questions about whether it is meaningful to claim to have a certain gender (say one different than the usual one for your sex) but be non-conformist to the usual social stereotypes. Or, indeed, what it would even mean to claim a given gender identity in the absence of such gender stereotypes and whether one can coherently support the idea of someone being transgender (as opposed to simply gender non-conforming) while opposing the idea of expectations of gendered behavior, i.e., in order to support the idea of someone claiming a different gender must one in some sense assent to the idea that it is appropriate to have certain gender specific expectations of behavior?
Interestingly, if on accepts the analysis I offer below, on which gender identity is ultimately about a preference between various gendered societal roles it may be that the suggestion in this article is in a sense conceptually self-defeating since if society ever got close to the point of adopting this solution the very concept of gender as distinct from sex would dissolve.
#### Why we should stop giving babies a gender when they are born
Trans rights have burst into the spotlight in the past few years thanks to high-profile figures like Laverne Cox and Caitlyn Jenner, with the former’s 2014 Time cover seen as a watershed moment for the movement. Now, the debate has turned to children and gender.
Before I go one I’d like to impress the importance of distinguishing theoretical considerations from more practical ones. For instance, one could believe that gender identity doesn’t really make sense because it rests on the inappropriate idea that we should have different expectations and social roles for men and women while believing that since, in the near term there is no practical means of eliminating those expectations/roles the best thing to do is to support people’s ability to change which set of expectations/roles apply to them (or make the effort of opting out). This isn’t quite the position I hold but I would like to stress that however the theoretical discussion turns out I firmly believe that, as a matter of simple human compassion and empathy, we should respect people’s requests to be referred to and treated as the gender they identify with. Regardless of whether the notion of gender is philosophically suspect or not it causes people real pain to be misgendered and doing so benefits no one. Even if you believe transgender identification is a mental disorder2 which doctors should try to cure rather than accede to refusing to gender colleagues as they request or let them use the restroom of their choice, like screaming at someone whose religious beliefs you disagree with, accomplishes nothing but making more people miserable.
#### Tentative Thoughts
These kind of questions push me towards the view that the only sense in which one can claim to have a certain gender (as distinct from sex) is insofar as one is announcing an intention to comply more with the social expectations of and fulfill the social role of your chosen gender and requesting others apply those expectations to you. Obviously, one need not intend to comply with all the stereotypes and expectations society has of your chosen gender or request they all be applied to you but by announcing a particular gender identity one is suggesting that in the main you intend to comply with or wish to be treated according to the stereotypes for your chosen gender more so than the other gender. Or in the case of a declaration of a non-binary gender identity that one doesn’t intend to fill either social role and doesn’t wish to be treated as if one belongs in either.
Ultimately, this means that there is a certain sense in which I don’t think it makes sense to ‘really’ be intrinsically male (female) despite being biologically female (male). There is no societally independent objective notion of gender relative to which one is really male or female. There are only certain societal roles, expectations and stereotypes about men and women and attitudes people have about how they wish to relate to those roles, expectations and stereotypes. Thus, its simply incoherent to claim that one’s gender is really female but that one doesn’t intend to play more of the stereotypical female role in social interactions nor does one want others to treat you more according to the usual social expectations we have of women. In other words, the only real concept of gender (as distinct from sex) which we have recourse to is the operational concept defined by way of society’s gendered expectations. As such, the common implicit assumption in discussions of gender identity that gender is some kind of intrinsic property of the individual must be rejected.
To be clear I’m not suggesting that talk of gender identity is misguided or can’t be made sense of. The operational definition (or a precisification thereof) I gave above works perfectly well and makes sense of what is going on when someone makes a male or female gender identity claim. However, it does suggest a certain skepticism about claims of gender identities other than male, female and none of the above (if gender is understood as a desire to be treated as if you belong/don’t belong to certain societal categories it doesn’t really make sense to call categories that society doesn’t have gender identities) and suggests a certain degree of skepticism regarding the implicit assumption of intrinsicness often made about gender. Accepting this view, however, does limit one’s ability to simultaneously claim to have a male/female gender identity while resisting the idea that gender specific social norms and stereotypes should be applied to you.
#### Gender As Personal Identification
I suspect a common response to my suggestion above is that I’m ignoring the very real sense in which some individuals strongly identify as a given gender. I fully accept the fact that some people simply feel male or female and are more comfortable thinking of themselves in that way. For those of us, like myself, who are cis by default such feelings certainly seem puzzling but I’m very much convinced they are real. But if I’m convinced these feelings are real why not just accept that the concept of gender merely refers to the sense of personal identification as male or female?
For one thing, the discussion of personal identification (driven by a noble desire to be inclusive) elides the fact that this can mean very different things to different people. I found the answers to this question I asked on quora about the experience of gender dysphoria quite illuminating. In particularly, it suggests that while some people’s experience of gender dysphoria is best described as a desire to be socially treated as a member of the other gender other individuals feelings were directly related to a feeling of discomfort with the genitalia they were born with. However, the focus on social role seems both more common and more faithful to the idea that gender is something distinct from biological sex (or even desired biological sex) and the operational definition above seems to capture the primary ways people want to use the term.
But why not go further and simply accept the claims of strong personal identification with a gender as defining the concept of gender? This, after all, seems to be what most transactivists seem to favor and would allow one to make sense of both the variety of non-binary gender identification and those individuals who want to both claim a given male/female gender identity while rejecting the operational aspects, i.e., the request to be treated according to gendered societal expectations or desire to fit into gendered roles.
Unfortunately, this approach has several serious flaws. First, it seems unable to cope with the phenomena of cis by default as such individuals lack any particular feeling of personal identification but we don’t want to deny they have the default cis gender. One could offer a disjunctive definition of gender but such unwieldy theoretical constructs should generally be avoided. Even more problematic is that such an approach fails to pick out a clear concept as what feelings count as identifying as a particular gender will vary from person to person. Of course, one might try and offer some kind of objective yardstick of male/female identifying against which various feelings can be measured but that just pushes the problem of choosing a conception of gender back a level. More broadly, it still leaves us in want of any sense in which we should regard a particular kind of feeling of identification to be a feeling of gender identification rather than some other kind of psycho-sexual identification.
Besides, as a purely practical matter it might be best if the transrights movement, at least temporarily, disassociated themselves from the idea that one can simply choose a word that describes how you feel about your gender’ and call that a gender-identity. Even if you don’t share my conceptual concerns about calling such identifications, no matter how sincerely felt, gender identities it may be a necessary tactical move just as it was tactically necessary for gays to disassociate themselves from other non-traditional relationships like polyamory in the pursuit of gay rights.
#### Philosophical Work
Yes, I’m aware that there is some philosophical work on this subject. Unfortunately, while there are a few interesting papers in the analytic tradition far too many are nothing but ideologically driven continentalesque concept association. Of the papers that are worth reading the only one that I’ve found which directly tackles these hard conceptual issues is “Science Fiction Double Feature: Trans Liberation on Twin Earth” but even this paper doesn’t, to my mind, give enough weight to how these terms are actually used and (perhaps motivated by understandable3 concerns about harmful effects on the trans rights movement or perhaps the authors simply don’t share these intuitions) avoids bullet biting when such bullets would conflict with transpositive ideology. However, It’s quite likely I’m unaware of some good work on this subject and would appreciate being pointed in the direction of other good analytic philosophy papers dealing with this subject.
1. For example, parents who are perfectly balanced between choosing to relocate to an area with far more boys than girls or an area with far more girls than boys could presumably consider the fact that the balance of probabilities favors their child being attracted to individuals with the other kind of genitals when they grow up.
2. Personally, I think even phrasing it this way is to miss the point. Of course transgender individuals are suffering from a mental disorder as is anyone experiencing mental anguish. The only relevant question is whether things like gender reassignment surgery or claiming a different gender identity are effective means to reduce that suffering and I believe the evidence suggests they are.
3. Understandable and well-intentioned perhaps but still, in my opinion, a mistake. It’s my view that people can sense when certain conclusions or arguments are being avoided out of concern for their harmful impact and this works to push many readers towards a generalized skepticism of such work. At least in the context of an academic philosophy paper where there is little risk of being quoted out of context in the mainstream media, far better to defang the best arguments that can be raised against a position (or at least the public rhetoric associated with a position) and bite any required bullets while showing that need not force one to take an unsupportive or uncompassionate position regarding the vulnerable group in question.
## Transgender and Transracial Philosophical Shenanigans
### Orthodox Conclusions For Unorthodox Reasons
For those who aren’t connected with the philosophical, social justice or anti social justice worlds let me start with a bit of background. A few weeks ago the feminist philosopher Rachel Tuvel wrote an article (pdf) suggesting that we should be sympathetic to hypothetical claims of transracialism (i.e. people like Rachel Dolezal who claim to feel like they are a member of a different race than society classifies them as) for the same reasons we are sympathetic to transgender individuals. In particular, Tuvel suggested that it might be appropriate to prioritize internal feelings when making group classifications.
Now I don’t find Tuvel’s paper particularly convincing as an argument for it’s stated thesis. However, I do find it much more compelling as a conditional argument: if our support for transgender individuals is justified then we should adopt the same attitude toward hypothetical claims of transracial identity1. In other words, you can’t both condemn the man on the street for failing to support the right2 of transgender individuals to be gendered as they request while simultaneously insisting that the straightforward appeals (people should be able to choose their own identity) must be thrown overboard and replaced with abstruse philosophical theories of gender and race in order to even consider a prima facia case for transracialism. Either the man on the street can correctly claim that none of the arguments/evidence in the cultural zeitgeist justify claims of transgender rights or those same arguments create at least a prima facia case for transracial rights.
There was an immediate, cacophonous backlash against Tuvel’s paper and over 500 philosophers signed an open letter demanding Hypatia (the journal the paper was published in) issue a retraction. Note that retractions are reserved almost exclusively for cases of research misconduct (even studies later discovered to have erroneous conclusions usually aren’t retracted) and journals have resisted retracting papers even when those papers (misleadingly) appear to be defending child abuse and congress is applying pressure. Now the reasons given in the open letter (impolite use of other gendered name, failure to consult trans or minority individuals about their experiences, lack of literature engagement) were pretty clearly pre-textual. Papers commonly don’t cite literature the author doesn’t believe will be helpful and the fact that no one could point to existing literature that countered Tuvel’s arguments is further evidence it was a smokescreen. This becomes even more apparent if you peruse some of the pieces written in protest.
Had Tuvel’s article been written in support of an orthodox position about transgender issues, e.g., our experience with racial identity shows how important it is to respect trans identity, no one would have done anything more than make polite suggestions. However, as it was, Tuvel’s article outlined a potential political reducto of trans rights advocacy (if you accept transgender next thing you know you’ll have to accept transracial people as well) and defended an idea that many minorities find offensive.
Rather than bang on about how awful it is that philosophers are putting ideological purity above intellectual principles I’ll let this excellent response do it for me and instead try to get to the bottom of the moral case for accepting (and accommodating) transgender and transracial identification as both a practical and theoretical matter. Ultimately, I do present what I believe to be straightforward considerations that distinguish the transracial and transgender cases but as they are ultimately mere consequentialist balancings of harms and benefits they do nothing to reduce the force of Tuvel’s reasoning against those who take transgender accommodation to be an obvious moral imperative whose justification doesn’t require marshaling (or even gesturing at) empirical evidence of costs and benefits.
#### Reactions Outside The Community
While the philosophical community was busy having a fit because someone (in good faith without animosity) dared to publish an article that didn’t genuflect in front of less privileged groups in precisely the correct way the reaction from the rest of the blogosphere was considerably different. Both esr and poppsych.org wrote pieces pointing out that categories belong to the society that makes them not the individual who is categorized and that people had no right to demand to be placed in a different category.
There is a great deal of truth in this. No matter how much you feel like a great baseball player we don’t let that internal feeling dictate how often you get sent out on the field. We do use both race and gender categories, to some extent, for this kind of practical assortment. As few individuals are bi we use the gender category to sort people into potential dates and potential rivals. We use race as a proxy for past (or potential future) discrimination and cultural background.
While the unwashed masses are more likely to simply insist “No a man is someone with a penis/Y chromosome” they are expressing a similar sentiment. Despite attempts by parts of the social justice community (not effective transgender advocates) to insist this is merely transphobia I think that (while transphobia surely plays some role3 for some segment of the public) this sentiment is best understood as a (poorly expressed) unwillingness to modify social categories merely because someone would prefer a different categorization. This is a perfectly reasonable reaction to have when someone requests you place them in a different category based on factors you don’t take to be relevant to membership in that category, e.g., pointing out you have a great batting average is relevant to being placed in the good baseball player category while feeling like a winner’ is not.
Thus, if you are advocating for transgender acceptance you owe the public an argument why the fact that transgender individuals desire to be classified differently justifies doing so when such desires usually don’t. Unfortunately, this controversy seems to suggest that any an attempt to formulate such an argument (rather than taking it for granted or offering pure emotional appeals) runs a serious risk of being met with open hostility from other transgender advocates. But, for whatever the reason, the choice to abandon friendly persuasion and adopt the presumption that disagreement is proof of transphobia (if not literally nazihood) does a deep disservice to trans individuals by turning potential supporters into enemies4.
#### Social Categories And Moral Duties
While it may be generally true that wishing to be classified differently, e.g., as a good baseball player, isn’t usually something that obligates us to change those categories it sometimes does. For instance, consider gay marriage. Despite it’s legal and religious trappings marriage is ultimately a societal category (society recognizes a certain class of people as being in a kind of approved sexual partnership). Even if we had adopted civil unions that gave homosexual couples all the legal rights of married individuals the discomfort caused by categorizing committed gay couples as merely having a civil union rather than a marriage created an obligation to change our conception of marriage to include single sex couples.
Note that, that the moral obligation with respect to gay marriage was to stop making prominent use of (both culturally and legally) a relationship category that excluded gays. The choice to recognize gay marriages as ‘marriages’ was merely the easiest way to achieve this but it would have been morally acceptable to instead promote civil unions into the preeminent legal and social standard for committed relationship, i.e., we would ask both straight and gay couples if they were civil unioned, laws would be drafted in reference to civil union status etc… Conversely, we would not have meet our moral obligation if we had accepted homosexual marriages as marriages only to demote marriage to second class status while reserving the highest social regard only for hetero marriage.’ Critically, while cases like gay marriage appear to be about changing the definition of words they are really about changing which concepts we give cultural and legal preeminence to.
Similarly, transgender advocates want us to give concepts that recognize voluntary identification/presentation the prominent social and legal role5 we currently give to male/female (whether or not we let the same word play that role). Whatever you think male/female mean you have to acknowledge that dividing people up by claimed (leaving aside non-binary) gender identity is a coherent way to categorize people and that we could use some term that refers to this categorization in the situations we now use male/female.
#### Categories and Moral Balancing
Ultimately, whether or not we have a moral obligation to change which categories we give legal/social importance is a matter of balancing harms and benefits. For instance, switching to a gay inclusive category of committed relationships imposed very little cost. All of the practical purposes we use the category of marriage for (distinguishing serious/non-serious romantic relationships, assigning legal rights/duties etc..) are equally well handled by a gay inclusive relationship category. Thus, there is little cost to promoting a gay inclusive notion of marriage into egal/social prominence. Conversely, eliminating the substantial practical burdens and emotional harms imposed by a hetero-only notion of marriage provides a great benefit to homosexuals as well as their friends/relatives. The minimal cost and large benefit are more than enough to overcome the presumption in favor of existing practice6.
In contrast, consider the proposal to give the category ‘good baseball player or self-identifies as a good baseball player’ the social role previously filled by the category ‘good baseball player.’ That would mean that merely identifying as a good baseball player would warrant being taken off the bench, draw praise from teammates and even (at the college or professional level) generate income. This would be a huge cost as it would totally gut the practical value of the category good baseball player. True, there is some unhappiness associated with being thought of as a bad baseball player but I think it’s fair to say that the benefits of having such a category outweigh the costs. Indeed, it is likely sociologically impossible to adopt such a proposal as people would inevitably resume using the category of actually being proficient at baseball under a different name and failing to enter that category would instill the same disappointment and frustration that exclusion from the category of good baseball players creates today.
This kind of analysis neatly explains why we shouldn’t recognize transracial/transethnic individuals at a legal level. While it is possible there are unrecognized individuals experiencing emotional suffering because they can’t legally change races there is no evidence such individuals exist at all (excepting, perhaps, Rachel Dolezal). Moreover, the harms involved in replacing the current notion of race with one that allowed self-identification would be significant7 as we use race/ethnicity as a proxy for a variety of obstacles individuals face on account of their skin color/culture. For instance transracial self-identification would allow people to obscure attempts to identify discriminatory treatment (hey guys we need a bunch of you to identify as black so we don’t get sued) or self-servingly take advantage of programs designed to offset/remedy these obstacles without having faced (or at least being statistically more likely to have faced) the obstacles themselves8. The situation is slightly more complicated when we consider the social role of racial identification but ultimately the analysis is the same9.
So what happens when we apply this kind of analysis to the demands of transgender advocates? I find the descriptions of gender dysphoria by transgendered individuals credible evidence of substantial suffering as a result of being classified10 as the ‘wrong’ gender (more pedantically as a result of society choosing to use a categorization they dislike in everyday social and legal interactions). Now what about the cost of changing our gender categories11? This depends greatly on the scope of the change being made. If all we seek to do is ensure that in workplaces, universities and other places of public accommodation that people can use the restroom, pronoun and gender classification they (attempt to) present as then the cost is extremely minimal. Coed restrooms may take some getting used to but present no dangers or substantial harms so I see no reason not to let people use restrooms of their choice. Correct honorifics are purely a matter of convention and the downsides of coming out trans outweigh any likely benefit from affirmative action style programs (and if it proves to be a problem they can be closed to trans individuals). Thus, I think the cost benefit analysis is pretty lopsided in favor of treating transgender individuals with the social pleasantries and restroom access they request. Indeed, I would argue that the cost is so low that simple good manners demands such treatment.
Of course, if you have a more expansive notion of what it means to accommodate transgender individuals which goes beyond mere terminology and politeness to require genuinely treating trans men/women indistinguishably from cis men/women the analysis changes. For instance, if you think lesbians are morally obliged to tear down the cotton ceiling by regarding all women (even including transgender women with cocks) as potential sexual partners the cost is substantial. Our sex drives don’t give a fuck about what facts are morally appropriate to consider in evaluating dates (race, wealth, obesity, and conformity with gender stereotypes are all huge determents of sexual interest) and trying to berate them into different behavior is a recipe for pain. Even the more modest demand that trans-women be welcome in (and supported by) all feminist organizations is dangerous. While trans-women may face more hardships than cis-women on average they don’t face the same hardships. For instance, a project examining hypothetical reluctance to introduce young girls to STEM fields and/or trying to offset this with later interventions should make distinctions on assigned gender as a youth12.
#### Tuvel, Transgender Activism and Non-Binary Identification
The analysis above is pretty obvious. When do you change the categories you regard as important: when the cost of doing so is less than the benefit reaped. This naturally begs the question why didn’t Tuvel (or any of her visible critics) avail themselves of it. I’m sure there are multiple reasons and I can only speculate here but my guess is that the practical, empirically oriented structure raises concerns that the feminist/trans philosophy orthodoxy would rather not confront.
For one, this structure puts the phenomenological particulars of the transgender experience front and center. The reason we should change our practices to accommodate transgender individuals (while resisting attempts by fuckers like me to insist on being called ‘God Emperor’) is that the former group experiences serious emotional distress and is making good faith requests while I’m just out for a lark. However, much of the social justice world has been very reluctant to try to characterize what constitutes a representative transgender experience lest they deny someone’s unique experience. Worse, this kind of analysis may not be quite so kind to non-binary identification13 not to mention treating transgender identity as fundamentally no different in kind from the desire to amputate a healthy limb (not a bad thing just a recognition that both are brute preferences for unusual things).
This is particular unfortunate because both from a practical and theoretical standpoint any attempt to advance transgender rights hinges on the nature of the transgender experience. The only reason for treating the requests of transgender individuals as legitimate and reasonable while denying trollish requests from people like me to be addressed as God Emperor (or the nutty transspecies individuals14) stems from our divergent experiences and resulting motivations. To ensure the support of the kind social justice critical intellectuals I linked above there needs to be a cogent intellectual defense of what makes the requests of transgender advocates reasonable in contrast to most requests to change behavior/language based on personal preference. While I find the utilitarian considerations here compelling most people need some kind of difference in kind and that must be rooted in the particular nature of transgender experience. Providing such an analysis is normally the role of philosophy but this controversy suggests it is unable to maintain even the fig leaf of dispassionate intellectual inquiry on this subject.
As a practical matter the transgender community also needs to provide an emotional narrative that average citizens can understand. Homosexual marriage won because everyday people understood the message: homosexuals have the same kind of feelings I do about sex and love only triggered by same gender individuals. If transgender individuals want to get their requests for social change accepted they need to tell a story about what it’s like to be transgender that makes the average citizen think: If I was in that situation I’d also want people to treat me like the gender I identified with.. That means backing away from the position that the individual uniqueness of transgender individuals prevents the identification of common experiences and conveying those experiences to the general public. Of course, this may require leaving some unusual allies behind just like the homosexuals had to leave the committed polyamorous triads behind to ensure the Obergefell decision but that’s how real progress happens.
1. While there are analyses of transgender (if accepted) or possible psychological/empirical facts that could be used to construct arguments in favor of supporting claims of transgender but not of transrace even most of the philosophical community (and even the transgender community I suspect) is unaware of these details. Thus, to the extent society at large has good grounds for supporting/accepting claims of transgender they can’t rely on these obscure considerations. I think Tuvel does a decent job of arguing that, if we set aside those more obscure/empirical points, the same considerations arise for transracial identity. Ultimately, my inclination is to say that it probably will turn on psychological/empirical facts that may not yet be widely known … but that kind of admission would not be acceptable by the orthodoxy.
2. You could criticize them for not extending to transgender people the normal human kindness of complying with requests made of us so long as they aren’t too burdensome but most trans advocates (at least in philosophical circles) tend to view any skepticism of the idea that transgender individuals have a right to be gendered as they request as proof of some moral failing.
3. As with homophobia a great deal of animosity (as opposed to mere difference of opinion about social structure) towards trans individuals is based on an ick factor (hence why gay men faced so much more opposition than lesbians). I think it’s important that rather than tell people they are bad for even having the feeling we let them know that it’s a common human reaction to even the thought of different physiology. When I was young I responded similarly to some aspect (her skin?) of my grandmother’s old age/illness but it dissipated quickly once it became familiar and certainly didn’t stop me from loving and respecting her. But telling people that innate human reactions they can’t control makes them a bad person is a good way to turn potential allies into enemies and ensure they never gain enough familiarity to eliminate that reaction.
4. Importantly, even people who would fight any attempt to discriminate against transgender individuals in the workplace may have different views on when individual preferences can justly require society to change the categories it uses. Rather than being anti-trans many people just feel that society has much less of a duty to be responsive to even very heartfelt and intense preferences.
5. As we will see the precise range or roles for which transgender individuals want to substitute these new categories makes a substantial difference in whether we have any moral obligation to do so.
6. It takes a great deal of effort to make such changes and enforcing such changes inevitably requires some level of social coercion and there is always the possibility of error. Thus, the burden is properly on the party attempting to argue we should change the categories we assign social/legal importance to.
7. At least assuming the policy consensus that it is good and appropriate to sometimes consider disadvantaged racial background in awarding government contracts, school admittance, hiring, etc.. If you think this consensus is harmful this analysis changes.
8. Of course the government/employer could simply record whether or not you were cis-black or trans-black and use that to recreate the original data (though it would make it easier to raise spurious objections based on a desire not to stigmatize transracialism). However, it’s not at all obvious merely changing the name of the box ticked from ‘non-black’ to ‘trans-black’ would offer any benefit to transracial individuals. If their status as transracial is used to deny them entry into programs open to cis-black individuals its hard to imagine they would feel they were being regarded as racially black.
9. The argument that we should replace the current social role of racial identification with something which allows identification based transition is somewhat more plausible. However, this too is problematic as one can’t separate cultural behavior from skin color/ancestry, e.g., the mere fact that I don’t have black skin means I can’t use the n-word with the same meaning as someone with black skin. So again the balance doesn’t favoring adopting categories that give a greater role to the feeling of identification to fill the role played by racial categories.
10. Whether or not that suffering is literally the result of not using the desired pronouns and gender ascriptions or merely correlates with non-acceptance and harassment isn’t clear. Maybe if some database screwup prevented trans individuals from having access to their preferred bathrooms or records made of their preferred pronouns but everyone was perfectly accepting it would be just as good but in practice we can assume that using desired pronouns and gender terms goes hand in hand with reduced suffering.
11. More pedantically, changing the categories we use to select pronouns, assign restrooms and use in everyday descriptive talk, e.g., “Ask the woman in the white blouse.”
12. Of course, while it would be appropriate to exclude trans-women it wouldn’t be appropriate to exclude trans-men but logical consistency has never done well against the rhetoric of privelege.
13. There are too many people claiming non-binary gender identity for purely political/expressive reasons, less clarity that using preferred pronouns/gender descriptions alleviates suffering for non-binary individuals, and the many non-binary genders impose substantial IT/forms/mental overhead costs. The real nail in the coffin, however, is the lack of any brightline to exclude clear attempts to hijack the norms for amusement/politics. People (rightly for fear of incentivizing more mischief) aren’t going to tolerate people like me asking to be addressed as Galactic Gerdes whatever the social justice scene says about galactic gender identity but once one starts accepting some non-binary identities it becomes dangerous to exclude others.
14. Personally, I’m not convinced they are any different than transgender individuals. They feel a certain way and respecting those feelings might make them happy. However, the feminist/trans philosophy community is certainly not willing to classify transgender as no different in kind than any other crazy, but emotionally intense and long term, life choice like voluntary amputation. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.26008856296539307, "perplexity": 1649.6849880310795}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-16/segments/1585371876625.96/warc/CC-MAIN-20200409185507-20200409220007-00521.warc.gz"} |
https://hal.inria.fr/inria-00099637 | # Automated Generation of Diagrams with Maple and Java
1 SPACES - Solving problems through algebraic computation and efficient software
INRIA Lorraine, LORIA - Laboratoire Lorrain de Recherche en Informatique et ses Applications
Abstract : This note shows how to draw diagrams automatically from the predicate specification of a given set of geometric relations among a set of points in the plane. It is done first in Maple by translating the geometric relations into polynomial equations, decomposing the obtained system of polynomials into irreducible representative triangular sets, and finding an adequate numerical solution from each triangular set. A Java class coding the solution and the polynomials in each triangular set is generated, compiled, and then executed with the main Java programs to draw a diagram. The whole process combining symbolic elimination in Maple with numerical computation, graphic drawing, and letter labelling in Java is fully automatic. The drawn diagrams may be animated and fine-tuned by mouse click and dragging and saved as PostScript files. We present the drawing method, discuss some techniques of implementation, and give several sample diagrams drawn by our program.
Mots-clés :
Type de document :
Chapitre d'ouvrage
M. Joswig, N. Takayama. Algebra, Geometry, and Software Systems, Springer-Verlag, Berlin Heidelberg, pp.277-287, 2003
Domaine :
https://hal.inria.fr/inria-00099637
Contributeur : Publications Loria <>
Soumis le : mardi 26 septembre 2006 - 09:39:38
Dernière modification le : jeudi 11 janvier 2018 - 06:20:00
### Identifiants
• HAL Id : inria-00099637, version 1
### Citation
Dongming Wang. Automated Generation of Diagrams with Maple and Java. M. Joswig, N. Takayama. Algebra, Geometry, and Software Systems, Springer-Verlag, Berlin Heidelberg, pp.277-287, 2003. 〈inria-00099637〉
### Métriques
Consultations de la notice | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.896745502948761, "perplexity": 4512.094384958607}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-05/segments/1516084886739.5/warc/CC-MAIN-20180116204303-20180116224303-00481.warc.gz"} |
http://cms.math.ca/cmb/msc/20D60?fromjnl=cmb&jnl=CMB | location: Publications → journals
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Search: MSC category 20D60 ( Arithmetic and combinatorial problems )
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1. CMB 2010 (vol 54 pp. 39)
Chapman, S. T.; García-Sánchez, P. A.; Llena, D.; Marshall, J.
Elements in a Numerical Semigroup with Factorizations of the Same Length Questions concerning the lengths of factorizations into irreducible elements in numerical monoids have gained much attention in the recent literature. In this note, we show that a numerical monoid has an element with two different irreducible factorizations of the same length if and only if its embedding dimension is greater than two. We find formulas in embedding dimension three for the smallest element with two different irreducible factorizations of the same length and the largest element whose different irreducible factorizations all have distinct lengths. We show that these formulas do not naturally extend to higher embedding dimensions. Keywords:numerical monoid, numerical semigroup, non-unique factorizationCategories:20M14, 20D60, 11B75
2. CMB 2007 (vol 50 pp. 632)
Zelenyuk, Yevhen; Zelenyuk, Yuliya
Transformations and Colorings of Groups Let $G$ be a compact topological group and let $f\colon G\to G$ be a continuous transformation of $G$. Define $f^*\colon G\to G$ by $f^*(x)=f(x^{-1})x$ and let $\mu=\mu_G$ be Haar measure on $G$. Assume that $H=\Imag f^*$ is a subgroup of $G$ and for every measurable $C\subseteq H$, $\mu_G((f^*)^{-1}(C))=\mu_H(C)$. Then for every measurable $C\subseteq G$, there exist $S\subseteq C$ and $g\in G$ such that $f(Sg^{-1})\subseteq Cg^{-1}$ and $\mu(S)\ge(\mu(C))^2$. Keywords:compact topological group, continuous transformation, endomorphism, Ramsey theoryinversion, Categories:05D10, 20D60, 22A10
3. CMB 2004 (vol 47 pp. 530)
Iranmanesh, A.; Khosravi, B.
A Characterization of $PSU_{11}(q)$ Order components of a finite simple group were introduced in [4]. It was proved that some non-abelian simple groups are uniquely determined by their order components. As the main result of this paper, we show that groups $PSU_{11}(q)$ are also uniquely determined by their order components. As corollaries of this result, the validity of a conjecture of J. G. Thompson and a conjecture of W. Shi and J. Bi both on $PSU_{11}(q)$ are obtained. Keywords:Prime graph, order component, finite group,simple groupCategories:20D08, 20D05, 20D60 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9776126742362976, "perplexity": 621.3257910073794}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657131846.69/warc/CC-MAIN-20140914011211-00277-ip-10-196-40-205.us-west-1.compute.internal.warc.gz"} |
https://economics.stackexchange.com/questions/41957/what-links-can-be-made-between-the-marginal-productivities-of-the-factors-of-pro | What links can be made between the marginal productivities of the factors of production and the costs of production [closed]
What links can be made between the marginal productivities of the factors of production and the costs of production
In a perfectly competitive markets for factors of production the marginal productivity of factors is equal to price of factor, which in turn decides the cost of production. For example, consider two factor production function $$Y=F(K,L)$$. At equilibrium, under assumption of perfect competition in market for both factors, $$F_K = r$$ and $$F_L = w$$, where $$F_K, F_L$$ are marginal products with of $$K$$ and $$L$$ respectively, and $$r, w$$ are respective prices of these factors.
Cost of production is $$C(Y)=rK+wL=F_K\cdot K+F_L\cdot L$$
This is the simplest link between marginal productivities and cost of production. In a partial equilibrium setting, with $$r, w$$ given, this can be further simplified to eliminate $$K$$ and $$L$$ (see equation (6) in this answer)
Assume the following profit function: $$\pi = pY - wL -rK$$ and a two factor economy $$Y(L,K)$$. Optimal labour and capital inputs for the firm can be found by taking the respective derivatives and setting them to zero:
$$\frac{\delta \pi}{\delta L} = p \frac{\delta Y}{\delta L} -w = 0 \iff \; \frac{\delta Y}{\delta L} = \frac{w}{p}$$
$$\frac{\delta \pi}{\delta K} = p \frac{\delta Y}{\delta K} -r = 0 \iff \; \frac{\delta Y}{\delta K} = \frac{r}{p}$$
Now you can see that marginal productivities are equal marginal costs. The derivative with respect to the input factor tells you what the next unit of capital or labour will produce and the right hand side tells you what they will cost (real wage or real interest rate). If this condition does not hold firms could be better off by adjusting their production towards this condition. For example assume marginal product of labour is greater than the real wage $$(\delta Y / \delta L > w / p)$$. The firm should hire an additional worker since she will produce more than she costs. This logic holds true until the conditions are fulfilled. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 16, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7385733127593994, "perplexity": 522.0172050564366}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-17/segments/1618038062492.5/warc/CC-MAIN-20210411115126-20210411145126-00292.warc.gz"} |
https://www.physicsforums.com/threads/free-body-diagram-on-a-piano.187698/ | Free Body Diagram on a Piano
1. Sep 28, 2007
C.Me.B
Identify the forces acting on the object of interest. From the list below, select the forces that act on the piano.
1. acceleration of the piano
2. gravitational force acting on the piano (piano's weight)
3. speed of the piano
5. force of the floor on the piano (normal force)
6. force of the piano on the floor
7. force of Chadwick on the piano
8. force of the piano pushing on Chadwick
I thought it would be 2, 5, 7, 8 But I might be missing something
I guess you would use Fnet= m*a
2. Sep 28, 2007
bob1182006
is 8 acting ON the piano? or is the piano acting on Chadwick? if it's not a force acting ON the piano then it isnt part of the answer.
but I think you have them all.
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https://www.ahay.org/RSF/book/sep/stack/paper_html/node12.html | Asymptotic pseudounitary stacking operators
Next: Velocity Transform Up: EXAMPLES Previous: 3. Common-offset migration
## Post-Stack Time Migration
An interesting example of a stacking operator is the hyperbola summation used for time migration in the post-stack domain. In this case, the summation path is defined as
(59)
where denotes the vertical traveltime, and are the horizontal coordinates on the migrated and unmigrated sections respectively, and stands for the effectively constant root-mean-square velocity (Claerbout, 1995). The summation path for the reverse transformation (demigration) is found from solving equation (59) for . It has the well-known elliptic form
(60)
The Jacobian of transforming to is
(61)
If the migration weighting function is defined by conventional downward continuation (Schneider, 1978), it takes the following form, which is equivalent to equation (40):
(62)
The simple trigonometry of the reflected ray suggests that the cosine factor in formula (62) is equal to the simple ratio between the vertical traveltime and the zero-offset reflected traveltime :
(63)
The equivalence of the Jacobian (61) and the cosine factor (63) has important interpretations in the theory of Stolt frequency-domain migration (Levin, 1986; Chun and Jacewitz, 1981; Stolt, 1978). According to equation (22), the weighting function of the adjoint operator is the ratio of (62) and (61):
(64)
We can see that the cosine factor disappears from the adjoint weighting. This is completely analogous to the known effect of dropping the Jacobian'' in Stolt migration (Harlan, 1983; Levin, 1994). The product of the weighting functions for the time migration and its asymptotic inverse is defined according to formula (10) as
(65)
Thus, the asymptotic inverse of the conventional time migration has the weighting function determined from equations (10) and (62) as
(66)
The weighting functions of the asymptotic pseudo-unitary operators are obtained from formulas (28) and (29). They have the form
(67) (68)
The square roots of the cosine factor appearing in formulas (67) and (68) correspond to the analogous terms in the pseudo-unitary Stolt migration proposed by Harlan and Sword (1986).
Figure 1 shows the output of a simple numerical test. The synthetic zero-offset section used in this test is shown in the left plot of Figure 2. The data are taken from Claerbout (1995) and correspond to a synthetic reflectivity model, which contains several dipping layers, a fault, and an unconformity. The input zero-offset section is inverted using an iterative conjugate-gradient method and two different weighting schemes: the uniform weighting and the asymptotic pseudo-unitary weighting (67-68). I compare the iterative convergence by measuring the least-squares norm of the data residual error at different iterations. Figure 1 shows that the pseudo-unitary weighting provides a significantly faster convergence. The result of inversion after 10 conjugate-gradient iterations is shown in Figures 2 and 3. The right plot in Figure 2 shows the output of the least-squares migration. Figure 3 shows the corresponding modeled data and the residual error. The latter is very close to zero. Although this example has only a pedagogical value, it clearly demonstrates possible advantages of using asymptotic pseudo-unitary operators in least-squares migration.
migiter
Figure 1.
Comparison of convergence of the iterative least-squares migration. The dashed line corresponds to the unweighted (uniformly weighted) operator. The solid line corresponds to the asymptotic pseudo-unitary operator. The latter provides a noticeably faster convergence.
migcvv
Figure 2.
Input zero-offset section (left) and the corresponding least-squares image (right) after 10 iterations of iterative inversion.
migrst
Figure 3.
The modeled zero-offset (left) and the residual error (right) plotted at the same scale.
Asymptotic pseudounitary stacking operators
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https://www.limswiki.org/index.php/Journal:The_GAAIN_Entity_Mapper:_An_active-learning_system_for_medical_data_mapping | # Journal:The GAAIN Entity Mapper: An active-learning system for medical data mapping
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Full article title The GAAIN Entity Mapper: An active-learning system for medical data mapping Frontiers in Neuroinformatics Ashish, N.; Dewan, P.; Toga, A.W. University of Southern California at Los Angeles Email: nashish@loni.usc.edu Van Ooyen, A. 2016 9 30 10.3389/fninf.2015.00030 1662-5196 Creative Commons Attribution 4.0 International http://journal.frontiersin.org/article/10.3389/fninf.2015.00030/full http://journal.frontiersin.org/article/10.3389/fninf.2015.00030/pdf (PDF)
## Abstract
This work is focused on mapping biomedical datasets to a common representation, as an integral part of data harmonization for integrated biomedical data access and sharing. We present GEM, an intelligent software assistant for automated data mapping across different datasets or from a dataset to a common data model. The GEM system automates data mapping by providing precise suggestions for data element mappings. It leverages the detailed metadata about elements in associated dataset documentation such as data dictionaries that are typically available with biomedical datasets. It employs unsupervised text mining techniques to determine similarity between data elements and also employs machine-learning classifiers to identify element matches. It further provides an active-learning capability where the process of training the GEM system is optimized. Our experimental evaluations show that the GEM system provides highly accurate data mappings (over 90 percent accuracy) for real datasets of thousands of data elements each, in the Alzheimer's disease research domain. Further, the effort in training the system for new datasets is also optimized. We are currently employing the GEM system to map Alzheimer's disease datasets from around the globe into a common representation, as part of a global Alzheimer's disease integrated data sharing and analysis network called GAAIN. GEM achieves significantly higher data mapping accuracy for biomedical datasets compared to other state-of-the-art tools for database schema matching that have similar functionality. With the use of active-learning capabilities, the user effort in training the system is minimal.
Keywords: data mapping, machine learning, active learning, data harmonization, common data model
## Background and significance
This paper describes a software solution for biomedical data harmonization. Our work is in the context of the “GAAIN” project in the domain of Alzheimer's disease data. However, this solution is applicable to any biomedical or clinical data harmonization in general. GAAIN — the Global Alzheimer's Association Interactive Network — is a data sharing federated network of Alzheimer's disease datasets from around the globe. The aim of GAAIN is to create a network of Alzheimer's disease data, researchers, analytical tools and computational resources to better our understanding of this disease. A key capability of this network is also to provide investigators with access to harmonized data across multiple, independently created Alzheimer's datasets.
Our primary interest is in biomedical data sharing and specifically harmonized data sharing. Harmonized data from multiple data providers has been curated to a unified representation after reconciling the different formats, representation, and terminology from which it was derived.[1][2] The process of data harmonization can be resource-intensive and time-consuming; the present work describes a software solution to significantly automate that process. Data harmonization is fundamentally about data alignment, the establishment of correspondence between related or identical data elements across different datasets. Consider the very simple example of a data element capturing the gender of a subject that is defined as “SEX” in one dataset, “GENDER” in another and “M/F” in yet another. When harmonizing data, a unified element is needed to capture this gender concept and to link (align) the individual elements in different datasets with this unified element. This unified element is the “G.GENDER” element as illustrated in Figure 1.
Figure 1. Data element mapping.
The data mapping problem can be solved in two ways as illustrated in Figure 1. We could map elements across two datasets, for instance match the element “GENDER” from one data source (DATA SOURCE 1 in Figure 1) to the element “SEX” in a second source (DATA SOURCE 2). We could also map elements from one dataset to elements from a common data model. A common data model is a uniform representation which all data sources or providers in a data sharing network agree to adopt. The fundamental mapping task is the same in both. Also, the task of data alignment is inevitable regardless of the data sharing model one employs. In a centralized data sharing model[3], where we create a single unified store of data from multiple data sources, the data from any data source must be mapped and transformed to the unified representation of the central repository. In federated or mediated approaches to data sharing[1] individual data sources (such as databases) must be mapped to a “global” unified model through mapping rules. The common data model approach, which is also the GAAIN approach, also requires us to map and transform every dataset to the (GAAIN) common data model. This kind of data alignment or mapping can be labor intensive in biomedical and clinical data integration case studies.[4] A single dataset typically has thousands of distinct data elements of which a large subset must be accurately mapped. And it is widely acknowledged that data sharing and integration processes need to be simplified and made less resource-intensive for data sharing, for them to become a viable solution for the medical and clinical data sharing domain as well as the more general enterprise information integration domain.[5] The GEM system is designed to achieve this by providing automated assistance to developers for such data alignment or mapping.
The GEM data mapping approach is centered on exploiting the information in the data documentation, typically in the form of data dictionaries associated with the data. The importance of data dictionary documentation, and for Alzheimer's data in particular, has been articulated by Morris et al.[6] These data dictionaries contain detailed descriptive information and metadata about each data element in the dataset. Our solution is based on extracting this rich metadata in data dictionaries, developing element similarity measures based on text mining of the element descriptions, and employing machine-learning classifiers to meaningfully combine multiple indicative factors for an element match.
## Materials and methods
Here we report the second version of the GEM system.[7] The first version (GEM-1.0)[7], deployed in December 2014 is a knowledge driven system. Element matches are determined in a heuristic manner based on element similarity derived off the element metadata in data dictionaries. In this second version (GEM-2.0), completed in April 2015, we added machine-learning based classification to the system. We have further added capabilities of active-learning[8] where the user effort in training the machine-learning classifiers in the system is minimized.
While GEM-2.0 data mapping is powered by machine-learning classification, it employs the element metadata extraction developed in GEM-1.0 for synthesizing features required for classification. In this section we will describe the extraction of metadata from data dictionaries and element similarity metrics as developed in GEM-1.0. We then describe the machine-learning classification capabilities developed in GEM-2.0. The last sub-section describes the active-learning capability for training the system for new datasets, in an efficient manner. Before describing the system however, we clarify some terminology and definitions.
• A dataset is a source of data. For example, a dataset provided by “ADNI” is a source.
• A data dictionary is the document associated with a dataset, which defines the terms used in the dataset.
• A data element is an individual “atomic” unit of information in a dataset, for instance a field or a column in a table in a database or in a spreadsheet.
• The documentation for each data element in a data dictionary is called element metadata or element information.
• A mapping or element mapping is a one-to-one relationship across two data elements, coming from different sources.
• Mappings are created across two distinct sources. The element that we seek to match is called the query element. The source we must find matches from is called the target source, and the source of the query element is called the query source. (Note: A common data model may also be treated as a target source.)
• For any element, the GEM system provides a set of suggestions (typically five). We refer to this set as the window of suggestions.
### Metadata extraction for element similarity
Medical datasets, including datasets in domains such as Alzheimer's disease, are typically documented in data dictionaries. The data dictionary provides information about each element, including descriptions of the data element and other details such as its data type, range or set of possible values etc.
Figure 2 illustrates some snippets from a data dictionary for a particular Alzheimer's disease dataset. The element described (on the left) is called “BILLS” and includes a short as well as a more complete description of this data element. We are also provided information about its type (numeric code in this case) and also the possible values it can take, i.e., one of {0,1,2,3,8}. Such element information is the basis for identifying GEM element mappings.
Figure 2. Element information in data dictionary.
As a data mapping system GEM operates as follows:
• Elements are matched based on a metric of element similarity that is assessed by using the above illustrated metadata for each element.
• Such metadata is first extracted from the data dictionaries (of the datasets to be matched) and stored in a metadata database.
• Elements are matched from a source dataset to a target dataset. For instance we may be interested in finding mappings between two datasets such as ADNI and say “NACC” of which one would be the source and the other the target.
The target may also be a common data model. The elements of the common model are treated as (data) elements of a target data model.
• In determining the possible matches for a given data element, some of the metadata constraints are used for “blocking,” i.e., elimination from consideration of improbable matches. For instance an element (such as say BILLS) that takes one of five distinct coded values (as illustrated above) cannot match to an element such as BLOOD PRESSURE that takes values in the range 90–140.
• Probable matches for a data element are determined using element similarity. The element similarity is a score that captures how well (or not) the corresponding text descriptions of two data elements match. This text description similarity is computed using two approaches.
One is to use a TF-IDF cosine distance on a bag-of-words representation of the text descriptions. TF-IDF, short for term frequency–inverse document frequency, is a numerical statistic that is intended to reflect how important a word is to a document in a collection or corpus.[9]
Another approach requires building a topic model[10] over the element text descriptions and using the topic distribution to derive the similarity between two element text descriptions.
In machine learning and natural language processing, a topic model is a type of statistical model for discovering the abstract topics that occur in a collection of documents.[10] Such topics are not known in advance and are discovered dynamically during topic modeling. Topics are defined by a set of words from the document collection. After topic modeling a document is not assigned to a single topic (necessarily) but rather a document's topic is essentially a distribution over multiple topics. In the second approach for determining text similarity we compare how similar the topic distributions of two documents (element descriptions in this case) are.
Figure 3 illustrates the current GEM-2.0 architecture and workflow, GEM-1.0 had the same components minus the machine-learning classification modules, namely the boxes labeled “FEATURE EXTRACTOR” and “CLASSIFIER” to the right in Figure 3. In GEM-2.0 we also added a “NAME MATCH” module that determines the similarity of two element names. This module is capable of matching complex element names common in biomedical datasets and achieves this by segmenting complex element names into “components” and matching element names in a component wise fashion. In GEM-1.0 we determined element matches by (i) Blocking or filtering out improbable match candidates based on metadata constraints (the METADATA FILTER in Figure 1) and (ii) Ranking probable matches in order of the element similarity that was based on the element text description similarity. GEM-1.0 is described in more detail in Ashish et al.[7]
Figure 3. GEM architecture.
### Machine learning classification
Our motivation for the incorporation of machine-learning based classification for data mapping in GEM is two-fold. First, we have multiple indicators that can help in identifying element matches; for example, text similarity measures, other metadata constraints such as the element data type or set or range of possible values, and also a measure of the similarity of element names themselves. A classification approach can learn how to optimally combine such various indicators for an element match. Next, the GEM system is intended to operate as an intelligent software assistant that suggests data mappings to human data analysts and data integration developers. As such analysts and developers “select” correct matches (from alternatives provided by the system), implicitly providing training data to the system in terms of labeled data mapping examples. The system must incorporate this training data and improve the data mapping by leveraging the new knowledge.
The classification problem in our system is to determine, given a pair of element names (from the source and target), whether they match (Y) or not (N). We now describe the features employed for this task.
#### Features for classification
The classification is driven off features that are based on the metadata extracted and the computed element similarity. Note that the features as defined for a pair of data elements as the classification task is to classify element pairs into whether they match or not. The features are in four broad categories:
(i) Features based on the element text description similarity (ii) Features based on the element name (iii) Feature based on metadata constraints (iv) Other features
Table 1 provides the feature set for classification where we have provided the specific features, what they essentially represent and their possible values. Many of these features are synthesized from the information extracted from the data dictionary about the elements. For instance the text description similarity scores and ranks are synthesized from the element text descriptions, this is described in more detail in Ashish et al.[7] The name match score is provided by a name-matching classification module. Other features like the element cardinality or range are extracted directly from the data dictionary.
Table 1. Set of features for classification.
The Table Correspondence Score needs some explanation. Most datasets are originally housed in database systems, often in relational database management systems in a relational format. Data elements are thus organized and grouped into specific tables, for instance all patient information and demographic elements (patient age, gender, ethnicity etc.,) would likely be represented as columns in a demographics table. The table association can be a useful indicator for data mapping. For instance if we know that certain elements such as AGE, RACE, ETHNICITY all belong to a certain table “X” in the source dataset, and that their corresponding matching elements all (or mostly) come from a table “Y” in the target dataset, then it is likely that a new element say GENDER also from table X in the source has its corresponding matching element in table Y in the target. The literal table names of elements are not usable features, as the system would, at best, only learn about the specific table correspondences in the training data. This would not scale to unseen table names in the data that must be actually mapped. We have thus synthesized a feature called the table correspondence score which is a measure of how well two tables (one from the source and the other from the target) “correspond.” Employing the metadata constraints and the element text description similarity, we can determine the “best” match for a source element, this is essentially what GEM-1.0 does. The table correspondence score (TCS) captures the proportion of such best matches across data elements from two tables and is defined as:
${\displaystyle TCS(e_{S},e_{T})={\frac {M(e_{S},e_{T})}{\min(O(Tab(e_{S})),O(Tab(e_{T})))}}}$
where,
${\displaystyle {\begin{matrix}Tab(e){\text{is the table to which element }}e{\text{ belongs}}\\M(e_{S},e_{T})={\begin{cases}1&\quad {\text{if best match of }}e_{S}{\text{ is in }}Tab(e_{T})\\0&\quad {\text{otherwise }}\\\end{cases}}\\O(Tab(e))={\text{size of the table of element }}e{\text{ (number of columns in table)}}\\\end{matrix}}}$
The FEATURE EXTRACTOR module (Figure 3) compiles these above features from the metadata database. The CLASSIFIER module is a suite of machine-learning classifiers that can be trained on annotated training data for a pair of datasets to be mapped. We have experimented with multiple kinds of classifiers including functional classifiers such as Support Vector Machines (SVM) and Logistic Regression, tree based classifiers such as Random Forest and Simple CART, hybrid classifiers such as Sequential Minimal Optimization (SMO) and also neural network classifiers such as the Multi-Layer Perceptron.[11] A comparative analysis of the relative performance of these classifiers is provided in the Results section.
### Active learning
The GEM system is intended for use as an intelligent software assistant that provides precise mapping suggestions but it is a human analyst that finally accepts or rejects suggested element mappings. This forms the basis for active-learning in GEM where the user is also provided assistance by the system in intelligently selecting data mapping instances for training. The GEM user interface (UI) serves a dual purpose as an intelligent assistant to help with mappings, and also as an active-learning tool that collects data for training.
Active learning[8] itself is a special case of semi-supervised machine learning in which a learning algorithm is able to interactively query the user (or some other information source) to obtain the desired outputs at new data points. There are situations in which unlabeled data is abundant but manual labeling is expensive. In such a scenario, learning algorithms can actively query the user/teacher for labels. Since the learner chooses the examples, the number of examples to learn a concept can often be much lower than the number required in normal supervised learning.
Algorithms for determining which data points should be labeled can be organized into a number of different categories.[11] These include (i) uncertainty sampling where we label those points for which the current model is least certain as to what the correct output should be, (ii) query by committee where a variety of models are trained on the current labeled data, and vote on the output for unlabeled data, (iii) label those points for which the “committee” disagrees the most, (iv) expected model change where we label those points that would most change the current model, (v) expected error reduction where we label those points that would most reduce the model's generalization error, and (vi) variance reduction where we label those points that would minimize output variance, which is one of the components of error. Figure 4 illustrates the two possibilities for assembling training data to train GEM classifiers.
Figure 4. Training data for GEM.
The first is “passive-learning” where a user must examine data dictionaries in a brute force manner and determine training instances. The second is to use active-learning where the system itself provides selected candidates for training instances, with the objective of significantly reducing user effort in determining good training instances. Figure 5A is a screenshot of the GEM data mapping user interface. Figure 5B illustrates the user options and workflow.
Figure 5. GEM data mapping and active learning interface. (A) GEM UI, (B) Process.
The user is provided a set of suggested matches for a data element as shown in Figure 5A. He or she can then (i) Approve a match if he can identify a correct match from within the suggestions, (ii) Ask for more match suggestions, (iii) Skip a particular training instance, and (iv) Finally choose to end the training data collection session. The UI also provides information about each suggested match such as its text description and associated metadata (not illustrated) to help the user determine if it is a match or not. The green highlight in the “Mappings” box in the UI in Figure 5A indicates that the user has vetted that element match as the correct one. The red highlights indicates match suggestions provided by the system that the user explicitly marks as incorrect.
### Estimating user effort
It is important to quantify the user effort with either passive-learning or active-learning, objectively. The effort is directly related to the number of data elements that a user must examine in determining a match and we thus employ the number of data elements examined as the matric. In active-learning, for a given source data element, the system suggests matches for that element in the order of the “rank” based on the text description match scores. Assuming that the user examines target elements in the order suggested by the GEM UI, the number of (target) elements examine per source element is simply the rank of the correct target match element. For instance if the rank of the correct target match is "9," the user would examine nine elements from the UI in serial order and stop at the ninth element identifying it as a correct match. The total effort to determine N training instances is thus:
${\displaystyle {\begin{matrix}{\begin{array}{l}{E=\Sigma _{i=1\,to\,N}\,r\left(e_{i}\right)}\\\end{array}}\\{\text{where }}r(e)={\text{rank of element }}e\\\end{matrix}}}$
Estimating the effort for passive-learning, even in terms of the number of elements examined, is somewhat subjective. It depends on factors such as the user's familiarity with the domain, familiarity with the scientific concepts that the data elements represent, and also any prior knowledge of the particular dataset(s) to be mapped. We conducted an assessment where we tasked multiple developers—graduate students and data analysts to manually determine mappings across pairs of GAAIN datasets. The developers had varying degrees of familiarity with the Alzheimer's disease domain and datasets. We determined that the average number of target data elements examined per instance was approximately ${\displaystyle {\frac {N}{4}}}$ where N is the size of the target dataset (number of data elements). We will thus estimate the passive-learning effort in terms of this model, if the user ascertains K truth set mappings we estimate that the passive-learning mapping determination effort is ${\displaystyle {\frac {KN}{4}}}$.
### GEM system
As a software system GEM is written in Java. It employs the following tools and libraries—(i) the H2 main memory relational database, (ii) the Mallet toolkit for topic modeling and (iii) the Weka toolkit for machine-learning classification. The system works in a scalable fashion on a regular desktop or laptop computer with Java being the only requirement. We are currently working on (a) making the GEM software available for use free and open-source to the community and (b) providing the GEM data mapping capabilities as a service that can be invoked over an API.
## Results
We conducted a series of experimental evaluations with GEM-2.0 system, which are centered on evaluating the mapping accuracy with machine-learning classification added, and also the effort in training the system for mapping.
### Experimental setup
The experimental evaluations have been conducted on data mapping across various GAAIN datasets from different institutions. We used six of the data sources of Alzheimer's disease data that we have in GAAIN namely (1) the Alzheimer's Disease Neuroimaging Initiative (ADNI)[12], (2) the National Alzheimer's Coordinating Center database (NACC)[13], (3) the Dominantly Inherited Alzheimer Network database (DIAN)[6], (4) the Integrated Neurogenerative Disease Database (INDD)[14], (5) the Layton Aging and Alzheimer's Disease Center database (LAADC)[15], and (6) the Canadian Longitudinal Study of Aging (CLSA).[16] The data providers provided us with data dictionaries for all of these sources. We manually created truth sets of data mappings across these dataset pairs, which are used as the gold standard against which GEM generated mappings and training effort are evaluated. Each of these datasets contains between five and then thousand distinct data elements. On an average, between any two dataset pairs from the above, we have about 200 elements that correspond across both datasets. The duration to determine these mappings manually was about three days per pair on average, and with the actual time effort ranging between eight and 12 hours per pair. The mappings cannot be typically done in “one sitting” as the process may require seeking additional documentation or understanding of the data elements. The manual mappings were done by graduate students and data analysts with some familiarity of the neuro-informatics domain.
### Mapping accuracy with classification
The first experiment is to evaluate the impact of using GEM-2.0 (with machine-learning classification for matching) vs. GEM-1.0 (with no machine-learning classification). Figure 6A shows the mapping accuracies achieved, across various pairs of GAAIN datasets, with GEM-2.0 and GEM-1.0. The mapping accuracy is provided as F-Measure which is a metric that combines the precision as well recall—of the matches in this case. In pattern recognition and information retrieval with binary classification, precision is the fraction of retrieved instances that are relevant, while recall is the fraction of relevant instances that are retrieved.[17] F-Measure itself is defined as: ${\displaystyle F-Measure\ =\ 2.{\frac {precision.recall}{precision+recall}}}$.
Figure 6. Mapping accuracy. (A) Mapping accuracy, (B) Classifiers.
The mapping accuracy achieved with machine-learning classification in GEM-2.0 is high, at above 90 percent (with a suggested matches window size of five) for all schema pairs (shown for only three pairs). GEM-2.0 is also significantly more accurate compared to GEM-1.0, thus establishing the importance of a classification approach over features. We evaluated multiple classifiers illustrated the best 3 in Figure 6B and determined that the hybrid SMO classifiers performs best for this task. We also analyzed the relative importance of the various features. Figure 7 lists the most important classification features in terms of the information gain associated with each feature. Information gain is an entropy based metric that essentially captures how discriminative (or not) an attribute or feature is for a classification task.[11] The information gain, while shown for one pair of schemas, is representative of the importance obtained for all other pairs. We see that the two text matching scores and ranks are the most important features driving the major part of the classification. We also observe that the TF-IDF based text match information is more informative compared to what the topic model match provides.
Figure 7. Feature relevance.
### Training effort with active learning
The objective of an active-learning capability is to make system training efficient. We assess the user effort in training the system with active-learning and provide a comparative estimate with the effort required with passive-learning. Table 2 illustrates the user effort, in terms of elements examined, for identifying truth set mapping sets, of increasing sizes. We show the effort for both active and passive learning (in terms of total number of elements that had to be examined). For active learning we employed two slightly different strategies for the user, namely: Strategy 1: For a given element, repeatedly request more suggestions until the correct match is shown and identified. Strategy 2: Skip the element if the matching element is not found in the initial set of suggestions. We also provide the mapping accuracy of the GEM system at each stage, i.e., after training it with the examples identified for the truth set.
Table 2. Impact of active-learning on user effort.
As Table 2 shows, the effort required is about 10 times more with passive-learning than with active-learning. The average number of target elements examined per source element is 250 elements with passive-learning whereas it is slightly above 20 elements on average for active-learning (Strategy 2). We also observe that a high mapping accuracy can be achieved with training the system with a modest number of training examples.
## Discussion
The objectives of the GEM system are similar to that of eMERGE[18], which is a system for mapping phenotype data elements to standard data elements from ontologies such as the UMLS and SNOMED CT.[19] The eMERGE approach to mapping is purely knowledge driven, based upon simple lexical matches to ontology concepts in “pre-coordination” and “post-coordination” phases, depending upon whether the semantic terms have been previously seen and mapped or not, respectively. This approach is currently not applicable to the GEM environment where we may be mapping data across two dataset schemas vs. from a dataset to common data elements from ontologies. In the longer term however, as the GAAIN common model evolves and as we anchor GAAIN common model terms to standard data elements such as CDISC[20], we could consider the addition of such semantic mapping techniques to GEM. The analysis on the element text descriptions in GEM is significantly more sophisticated. Further, GEM also exploits metadata details such as element codes, ranges of values etc., for mapping which eMERGE does not. Data mapping is, in general, frequently performed manually based on data dictionaries, on any other information such as database design diagrams[1] and in consultation with the original dataset creators and/or administrators. Data mapping is well understood[21] and there are a number of software tools that have been developed in the past years that relate to it.
Existing tools can be categorized as metadata visualization tools, Extract-Transform-Load (ETL), and schema-mapping tools. Metadata visualization tools are those that create a visual representation of the design of a database by examining the database itself. For instance SchemaSpy provides functionality of “reverse engineering” to create a graphical representation of metadata, such as an “ER” (Entity-Relationship) diagram [22] from the database metadata. Altova is a tool for analyzing and managing relationships among data in data files in XML. These tools are relevant to our task as they can be employed to examine the data and/or metadata of new datasets. ETL tools provide support for data schema mapping. However, the mappings are not automated and have to be created by hand using a graphical user interface (GUI). Tools in this category include Talend, Informatica and Clio.[5]
The category most relevant to our data mapping problem is schema-mapping, which provides automated mapping of data elements from two different database or ontology schemas. These tools take as input the data definition language or “DDL”[22] associated with a dataset (database) and match elements across two database schemas based on the DDL information. Prominent examples in this category include the Harmony schema-mapping tool from the Open Information Integration or OpenII initiative and COMA++.[23] There are also schema-mapping tools that are based on “learning-from-examples,” i.e. the system is trained to recognize data element mappings from a tagged corpus of element matches (from the domain of interest). LSD [21] is an example in this category. Another tool is Karma [24] which has more of an ontology alignment focus as opposed to data (element) mapping. Karma has been employed for data mapping tasks in a variety of domains including in bioinformatics for mapping various drug databases to a common ontology, and also other domains such as geospatial data and environmental data. Finally, PhenoExplorer[25] is an online tool that allows researchers to identify research studies of interest. Specifically, a researcher can search for studies along a set of dimensions, including race/ethnicity, sex, study design, type of genetic data, genotype platform, and diseases studied and the system determines the relevance of a study by mapping data elements in a study to dimensions specified by a researcher. Our work was motivated by the observation that the rich metadata available in data dictionaries of biomedical datasets can be leveraged toward a significantly more automated approach to schema-mapping than could be achieved with existing tools.
## Conclusion
We have described and evaluated the GEM-2.0 system in this paper. Compared to the existing state-of-the-art in schema mapping, the GEM system is better suited to and optimized for biomedical data mapping such as in Alzheimer's disease research. Our experimental evaluations demonstrate significant mapping accuracy improvements obtained with our approach, particularly by leveraging the detailed information synthesized for data dictionaries. The addition of machine-learning classification has helped us achieve significantly high accuracy of data mapping with real datasets. We have also demonstrated that with active-learning the system can be trained very efficiently with a very small number of training examples and minimal data element examination effort, to map data accurately in new datasets. Finally, the system and technology are applicable to data matching in any biomedical domain as the system is driven by biomedical data dictionaries not restricted to any domain or disease and can be trained with match examples specific to a domain of interest. GEM is currently also being applied to other data harmonization efforts in neuro-informatics but not restricted to Alzheimer's disease, for instance in a project on biomedical big data discovery where the focus is on developing a biomedical big data analysis infrastructure that is applicable to any biomedical domain or disease.
## Conflict of interest statement
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
## Acknowledgments
This research was supported by the GAAIN project which is funded by the Alzheimer's Association under grant number 003278-0001 and by the Laboratory of Neuro Imaging Resource (LONIR) NIH grant number P41EB015922. Additional research support was provided by the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health under award number U54EB020406.
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## Notes
This presentation is faithful to the original, with only a few minor changes to presentation. In some cases important information was missing from the references, and that information was added. References are in order of appearance rather than alphabetical order (as the original was). Some grammar, punctuation, and minor wording issues have been corrected. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 6, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.24567072093486786, "perplexity": 2144.8115514025712}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623487660269.75/warc/CC-MAIN-20210620084505-20210620114505-00141.warc.gz"} |
http://ejde.math.txstate.edu/Volumes/2003/47/abstr.html | Electron. J. Diff. Eqns., Vol. 2003(2003), No. 47, pp. 1-25.
Oscillation for equations with positive and negative coefficients and distributed delay II: Applications Leonid Berezansky & Elena Braverman
Abstract:
We apply the results of our previous paper "Oscillation of equations with positive and negative coefficients and distributed delay I: General results" to the study of oscillation properties of equations with several delays and positive and negative coefficients
integrodifferential equations with oscillating kernels and mixed equations combining two above equations. Comparison theorems, explicit non-oscillation and oscillation results are presented.
Submitted February 14, 2003. Published April 24, 2003.
Math Subject Classifications: 34K11, 34K15.
Key Words: Oscillation, non-oscillation, distributed delay, equations with several delays, integrodifferential equations.
Show me the PDF file (272K), TEX file, and other files for this article.
A related article has been published by the same authors in this journal: Oscillation for equations with positive and negative coefficients and with distributed delay I: General results, Vol. 2003(2003), No. 12, pp. 1-21.
Leonid Berezansky Department of Mathematics Ben-Gurion University of the Negev Beer-Sheva 84105, Israel e-mail: brznsky@cs.bgu.ac.il Elena Braverman Department of Mathematics and Statistics University of Calgary 2500 University Drive N. W., Calgary, Alberta, Canada, T2N 1N4 Fax: (403)-282-5150, phone: (403)-220-3956 email: maelena@math.ucalgary.ca | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8805644512176514, "perplexity": 5594.2518667420845}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-50/segments/1480698541556.70/warc/CC-MAIN-20161202170901-00006-ip-10-31-129-80.ec2.internal.warc.gz"} |
http://debasishg.blogspot.com/2017/07/domain-models-late-evaluation-buys-you.html | ## Sunday, July 30, 2017
### Domain Models - Late Evaluation buys you better Composition
In the last post we talked about early abstractions that allow you to design generic interfaces which can be polymorphic in the type parameter. Unless you abuse the type system of a permissive language like Scala, if you adhere to the principles of parametricity, this approach helps you implement abstractions that are reusable under various contexts. We saw this when we implemented the generic contract of the mapReduce function and its various specializations by supplying different concrete instances of the Monoid algebra.
In this post we will take a look at the other end of the spectrum in designing functional domain models. We will discuss evaluation semantics of model behaviors - the precise problem of when to commit to specific concrete evaluation semantics. Consider the following definition of a domain service module ..
type ErrorOr[A] = Either[String, A]
trait PaymentService {
def paymentCycle: ErrorOr[PaymentCycle]
def qualifyingAccounts(paymentCycle: PaymentCycle): ErrorOr[Vector[Account]]
def payments(accounts: Vector[Account]): ErrorOr[Vector[Payment]]
def postToLedger(payments: Vector[Payment]): ErrorOr[Unit]
}
Such definitions are quite common these days. We have a nice monadic definition going on which can be composed as well to implement larger behaviors out of smaller ones ..
def processPayments() = for {
p <- paymentCycle
a <- qualifyingAccounts(p)
m <- payments(a)
_ <- postToLedger(a)
} yield ()
Can we improve upon this design ?
## Committing to the concrete early - the pitfalls ..
One of the defining aspects of reusable abstractions is the ability to run it under different context. This is one lesson that we learnt in the last post as well. Make the abstractions depend on the least powerful algebra. In this example our service functions return Either, which is a monad. But it's not necessarily the least powerful algebra in the context. Users may choose to use some other monad or may be even applicative to thread through the context of building larger behaviors. Why not keep the algebra unspecified at the service definition level and hope to have specializations in implementations or even in usages at the end of the world ? Here's what we can do ..
// algebra
trait PaymentService[M[_]] {
def paymentCycle: M[PaymentCycle]
def qualifyingAccounts(paymentCycle: PaymentCycle): M[Vector[Account]]
def payments(accounts: Vector[Account]): M[Vector[Payment]]
def postToLedger(payments: Vector[Payment]): M[Unit]
}
A top level service definition that keeps the algebra unspecified. Now if we want to implement a larger behavior with monadic composition, we can do this ..
// weaving the monad
def processPayments()(implicit me: Monad[M]) = for {
p <- paymentCycle
a <- qualifyingAccounts(p)
m <- payments(a)
_ <- postToLedger(a)
} yield p
Note that we are using only the monadic bind in composing the larger behavior - hence the least powerful algebra that we can use is that of a Monad. And we express this exact constraint by publishing the requirements of the existence of an instance of a Monad for the type constructor M.
Well, we could avoid the committment to a concrete algebra in the definition of the service. What about the implementation ? One of the core issues with the implementation is how you need to handle errors. This is an issue which often makes you commit to an implementation when you write the interpreter / implementation of a service contract. You may use Failure for a Try based implementation, or Left for an Either based implementation etc. Can we abstract over this behavior through a generic error handling strategy ? Some libraries like cats offers you abstractions like MonadError that helps you implement error reporting functionality using generic monadic APIs. Here's how we can do this ..
class PaymentServiceInterpreter[M[_]](implicit me: MonadError[M, Throwable])
extends PaymentService[M] {
//..
def payments(accounts: Vector[Account]): M[Vector[Payment]] =
if (accounts.isEmpty) me.raiseError(
new IllegalArgumentException("Empty account list"))
else //..
//..
}
//..
}
Note we needed a monad with error handling capabilities and we used MonadError for that. Note that we have kept the error type in MonadError as Throwable, which may seem a bit unethical in the context of pure functional programming. But it's also true that many libraries (especially Java ones) or underlying abstractions like Future or Try play well with exceptions. Anyway this is just a red herring though it has nothing to do with the current topic of discussion. The moot point is that you need to supply a MonadError that you have instances of.
Here's how cats defines the trait MonadError ..
trait MonadError[F[_], E] extends ApplicativeError[F, E] with Monad[F] { //..
.. and that's exactly what we will commit to. We are still dealing with a generic Monad even in the implementation without committing to any concreate instance.
## End of the World!
The basic purpose why we wanted to delay committing to the concrete instance was to allow the users the flexibility to choose their own implementations. This is what we call the principle of delayed evaluation. Abstract early, evaluate late and decouple the concerns of building and the evaluation of the abstractions. We have already seen the 2 of these principles - we will see that our design so far will accommodate the third one as well, at least for some instances of M.
The user of our API has the flexibility to choose the monad as long as she supplies the MonadError[M, Throwable] instance. And we have many to choose from. Here's an example of the above service implementation in use that composes with another service in a monadic way and choosing the exact concrete instance of the Monad at the end of the world ..
import cats._
import cats.data._
import cats.implicits._
import monix.cats._
for {
p <- paymentInterpreter.processPayments
e <- emailInterpreter.sendEmail(p)
} yield e
}
// future based computation
object FutureModule {
import scala.concurrent.Future
import scala.concurrent.ExecutionContext.Implicits.global
val paymentInterpreter = new PaymentServiceInterpreter[Future]
val emailInterpreter = new EmailServiceInterpreter[Future]
for {
p <- paymentInterpreter.processPayments
e <- emailInterpreter.sendEmail(p)
} yield e
}
object TryModule {
import scala.util.Try
val paymentInterpreter = new PaymentServiceInterpreter[Try]
val emailInterpreter = new EmailServiceInterpreter[Try]
for {
p <- paymentInterpreter.processPayments
e <- emailInterpreter.sendEmail(p)
} yield e
}
Monix Task is an abstraction that decouples the building of the abstraction from execution. So the Task that we get from building the composed behavior as in the above example can be executed in a deferred way depending of the requirements of the application. It can also be composed with other Tasks to build larger ones as well.
## Vertical Composition - stacking abstractions
When you have not committed to an implementation early enough, all you have is an unspecified algebra. You can do fun stuff like stacking abstractions vertically. Suppose we want to implement auditability in some of our service methods. Here we consider a simple strategy of logging as a means to audit the behaviors. How can we take an existing implementation and plugin the audit function selectively ? The answer is we compose algebras .. here's an example that stacks the Writer monad with an already existing algebra to make the payments function auditable ..
final class AuditablePaymentService[M[_]: Applicative](paymentService: PaymentService[M])
extends PaymentService[WriterT[M, Vector[String], ?]] {
def paymentCycle: WriterT[M, Vector[String], PaymentCycle] =
WriterT.lift(paymentService.paymentCycle)
def qualifyingAccounts(paymentCycle: PaymentCycle): WriterT[M, Vector[String], Vector[Account]] =
WriterT.lift(paymentService.qualifyingAccounts(paymentCycle))
def payments(accounts: Vector[Account]): WriterT[M, Vector[String], Vector[Payment]] =
WriterT.putT(paymentService.payments(accounts))(accounts.map(_.no))
//..
}
val auditablePaymentInterpreter = new AuditablePaymentService[Future](
new PaymentServiceInterpreter[Future]
)
We took the decision to abstract the return type in the form of a type constructor early on. But committed to the specific type only during the actual usage of the service implementation. Early abstraction and late committment to implementation make great composition possible and often in ways that may pleasantly surprise you later ..
Benoit said...
Breathtaking!
Thanks alot for this post!
Philippe Derome said...
Very nice blog! People on the conferences circle or significant OSS contributors may find this elementary but I think it's very useful for most Scala developers who are working in the enterprise (me) or for startups. Debasish is easier to follow than several other writers on FP in Scala arena by introducing sample code in context and discussing full context in sufficient detail. Not everybody knows how to compose abstractions with Writer (or Reader) monads as is done at the end of the blog. It's a beauty to see such a concise and clear exposure of non-trivial concepts. Maybe you could expand the WriterT at the end a little more to show the method calls that are being made? Or discuss how such a Writer Monad could be used to collect latency statistics for the audited calls (e.g. publishing to a service like Logstash)?
Readers should understand that a EmailService would be defined in way similar to PaymentService (not shown in blog).
If you like this blog, you'll probably like his book Functional and Reactive Domain Modeling at Manning. Readers may also like work Raul Raja Martinez on Freestyle project (I believe it's sponsored by 47 Degrees); he's made similar arguments on error handling as is made here.
zagubiony said...
Really good post, I have one question though. You parameterize with higher kinded type. Does it imply that you have to implement it every time you want to test it? Be it Future , Try or Task. Doesn't it make it not reusable ? I mean if I want to test it with unit test I don't want to return Future if all the data is stubbed, I would rather return Try but then I need Try -ish implementation which in turn requires from me implementing all the logic again. Is it really effective and worth it?
Debasish Ghosh said...
@zagubiony - You don't have to implement anything repeatedly. Note the entire implementation is in PaymentServiceInterpreter and it is completely independent of the instance of Monad that you are using. Look at the modules FutureModule or TryModule - you just instantiate with the type of Monad - Try or Future. This gives you the reusability.
zagubiony said...
@Debashish
thank you for your response. It's still not clear for me yet. Let me explain with some examples:
PaymentServiceInterpreter has various methods like payments and postToLedger let's assume that former needs DB and latter talks to 3rd party API/module. I can either implement those myself in PaymentServiceInterpreter itself (ie make the calls myself, fetch data from DB) or use the interface supplied in the constructor of the class. I am therefore dependent on those implementations or the return type of the calls I make.
I am really trying to understand it as I have had to cheat with Future.successful in my mocks in tests many times before and I really don't like this approach.
It would be much easier if you had maybe a repository with examples?
Thank you
Debasish Ghosh said...
@zagubiony - I think you are conflating 2 issues. In the implementation of the interpreter you can use any types that get returned from your third party library. e.g. your db access library may return a Try. The thing that we are trying to parameterize here is the contract between the interpreter and the external world. Suppose you have a method in your interpreter class as ..
// DB is an abstraction from your third party library
def qualifyingAccounts(p: PaymentCycle, db: DB): M[Vector[Account]] = {
// use DB to fetch from database
// do whatever you like with the result, use Try, Future etc.
// Finally when u return a Vector[Account] v, do this or
// call another function that returns a vector wrapped in an M monad
v.pure[M]
}
The contract of compositionality is just between the functions of the interpreter and possibly with other interpreters (we have not yet discussed it though). The only constraint that you need to honor is that the functions of the class return an M[_] and all errors are reported using MonadError. So the important part is to keep in mind is that within your implementation when you return errors, you need to use an abstraction that has an instance of MonadError.
HTH. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3002023994922638, "perplexity": 2275.9788522603294}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-43/segments/1508187823360.1/warc/CC-MAIN-20171019175016-20171019195016-00540.warc.gz"} |
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• Record: found
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Snaking states on a cylindrical surface in a perpendicular magnetic field
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Abstract
We calculate electronic states on a closed cylindrical surface as a model of a core-shell nanowire. The length of the cylinder can be infinite or finite. We define cardinal points on the circumference of the cylinder and consider a spatially uniform magnetic field perpendicular to the cylinder axis,in the direction South-North. The orbital motion of the electrons depends on the radial component of the field which is not uniform around the circumference: it is equal to the total field at North and South, but vanishes at the West and East sides. For a strong field, when the magnetic length is comparable to the radius of the cylinder, the electronic states at North and South become localized cyclotron orbits, whereas at East and West the states become long and narrow snaking orbits propagating along the cylinder. The energy of the cyclotron states increases with the magnetic field whereas the energy of the snaking states is stable. Consequently, at high magnetic fields the electron density vanishes at North and South and concentrates at East and West. We include spin-orbit interaction with linear Rashba and Dresselhaus models. For a cylinder of finite length the Dresselhaus interaction produces an axial twist of the charge density relative to the center of the wire, which may be amplified in the presence of the Rashba interaction.
Most cited references19
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Direct Measurement of the Spin-Orbit Interaction in a Two-Electron InAs Nanowire Quantum Dot
(2007)
We demonstrate control of the electron number down to the last electron in tunable few-electron quantum dots defined in catalytically grown InAs nanowires. Using low temperature transport spectroscopy in the Coulomb blockade regime we propose a simple method to directly determine the magnitude of the spin-orbit interaction in a two-electron artificial atom with strong spin-orbit coupling. Due to a large effective g-factor |g*|=8+/-1 the transition from singlet S to triplet T+ groundstate with increasing magnetic field is dominated by the Zeeman energy rather than by orbital effects. We find that the spin-orbit coupling mixes the T+ and S states and thus induces an avoided crossing with magnitude $$\Delta_{SO}$$=0.25+/-0.05 meV. This allows us to calculate the spin-orbit length $$\lambda_{SO}\approx$$127 nm in such systems using a simple model.
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Two-dimensional electrons in lateral magnetic superlattices
(1995)
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Spin states and persistent currents in mesoscopic rings: spin-orbit interactions
(2006)
We investigate theoretically electron spin states in one dimensional (1D) and two dimensional (2D) hard-wall mesoscopic rings in the presence of both the Rashba spin-orbit interaction (RSOI) and the Dresselhaus spin-orbit interaction (DSOI) in a perpendicular magnetic field. The Hamiltonian of the RSOI alone is mathematically equivalent to that of the DSOI alone using an SU(2) spin rotation transformation. Our theoretical results show that the interplay between the RSOI and DSOI results in an effective periodic potential, which consequently leads to gaps in the energy spectrum. This periodic potential also weakens and smoothens the oscillations of the persistent charge current (CC) and spin current (SC) and results in the localization of electrons. For a 2D ring with a finite width, higher radial modes destroy the periodic oscillations of persistent currents.
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Author and article information
Journal
23 May 2013
2013-11-14
1305.5577 10.1140/epjb/e2013-40735-5
Eur. Phys. J. B (2013) 86: 445
12 pages, 11 figures
cond-mat.mes-hall
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http://mathhelpforum.com/algebra/198617-simple-division.html | # Math Help - simple division?
1. ## simple division?
I have $\frac{(n+1)^n}{n^n}$
this somehow equals:
$(1+\frac{1}{n})^n$
Can someone show me the step in between? I just can't seem to make it work...
2. ## Re: simple division?
$\frac {(n+1)^n} {n^n}$
$\implies \big (\frac {n+1} {n} \big )^n$ [which is the same]
$\implies (1+\frac {1} {n})^n$ [separating the denominator for n and 1]
Thanks
3. ## Re: simple division?
thanks, I knew I was just missing something simple as always.
I appreciate the help. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 5, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9766729474067688, "perplexity": 4393.494211966657}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-35/segments/1440644066017.21/warc/CC-MAIN-20150827025426-00315-ip-10-171-96-226.ec2.internal.warc.gz"} |
http://verification.asmedigitalcollection.asme.org/article.aspx?articleid=2654279 | 0
Research Papers
# Verification Assessment of Piston Boundary Conditions for Lagrangian Simulation of the Guderley Problem
[+] Author and Article Information
Scott D. Ramsey
Mem. ASME
Applied Physics,
Los Alamos National Laboratory,
PO Box 1663, MS T082,
Los Alamos, NM 87545
e-mail: ramsey@lanl.gov
Jennifer F. Lilieholm
Department of Physics,
University of Washington,
3910 15th Ave NE,
Seattle, WA 98195
e-mail: liliej@uw.edu
Manuscript received March 30, 2017; final manuscript received September 5, 2017; published online September 26, 2017. Assoc. Editor: Jeffrey E. Bischoff.The United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States government purposes.
J. Verif. Valid. Uncert 2(3), 031001 (Sep 26, 2017) (14 pages) Paper No: VVUQ-17-1015; doi: 10.1115/1.4037888 History: Received March 30, 2017; Revised September 05, 2017
## Abstract
This work is concerned with the use of Guderley's converging shock wave solution of the inviscid compressible flow equations as a verification test problem for compressible flow simulation software. In practice, this effort is complicated by both the semi-analytical nature and infinite spatial/temporal extent of this solution. Methods can be devised with the intention of ameliorating this inconsistency with the finite nature of computational simulation; the exact strategy will depend on the code and problem archetypes under investigation. For example, scale-invariant shock wave propagation can be represented in Lagrangian compressible flow simulations as rigid boundary-driven flow, even if no such “piston” is present in the counterpart mathematical similarity solution. The purpose of this work is to investigate in detail the methodology of representing scale-invariant shock wave propagation as a piston-driven flow in the context of the Guderley problem, which features a semi-analytical solution of infinite spatial/temporal extent. The semi-analytical solution allows for the derivation of a similarly semi-analytical piston boundary condition (BC) for use in Lagrangian compressible flow solvers. The consequences of utilizing this BC (as opposed to directly initializing the Guderley solution in a computational spatial grid at a fixed time) are investigated in terms of common code verification analysis metrics (e.g., shock strength/position errors, global convergence rates). For the examples considered in this work, the piston-driven initialization approach is demonstrated to be a viable alternative to the more traditional, direct initialization approach.
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## References
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Morgan, N. , 2013, “ A Dissipation Model for Staggered Grid Lagrangian Hydrodynamics,” Comput. Fluids, 83, pp. 48–57.
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Banks, J. , Aslam, T. , and Rider, W. , 2008, “ On Sub-Linear Convergence for Linearly Degenerate Waves in Capturing Schemes,” J. Comp. Phys., 227(14), pp. 6985–7002.
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Runnels, S. , and Margolin, L. , 2013, “ An Integrated Study of Numerical Shock Shape, Artificial Viscosity, and Plasticity,” Los Alamos National Laboratory, Los Alamos, NM, Report No. LA-UR-13-24226.
LeVeque, R. , 2002, Finite Volume Methods for Hyperbolic Problems, Cambridge University Press, Cambridge, UK.
Arora, M. , and Roe, P. , 1997, “ On Postshock Oscillations Due to Shock Capturing Schemes in Unsteady Flows,” J. Comp. Phys., 130(1), pp. 25–40.
Noh, W. , 1987, “ Errors for Calculations of Strong Shocks Using an Artificial Viscosity and an Artificial Heat Flux,” J. Comp. Phys., 72(1), pp. 78–120.
Rider, W. , 2000, “ Revisiting Wall Heating,” J. Comp. Phys., 162(2), pp. 395–410.
Kamm, J. , Rider, W. , and Brock, J. , 2003, “ Combined Space and Time Convergence Analysis of a Compressible Flow Algorithm,” AIAA Paper No. 2003-4241.
Doebling, S. , and Ramsey, S. , 2013, “ Impact of Artificial Viscosity Models on Verification Assessment of a Lagrangian Hydrodynamics Code Using the Sedov Problem,” Los Alamos National Laboratory, Los Alamos, NM, Report No. LA-UR-13-23559.
Pederson, C. , Brown, B. , and Morgan, N. , 2016, “ The Sedov Blast Wave as a Radial Piston Verification Test,” ASME J. Verif. Valid. Uncertainty Quantif., 1(3), p. 031001.
Caramana, E. , and Whalen, P. , 1998, “ Numerical Preservation of Symmetry Properties of Continuum Problems,” J. Comp. Phys., 141(2), pp. 174–198.
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## Figures
Fig. 1
Guderley density solution (k = 2, γ = 1.4, ρ0 = 1.0) as a function of r, evaluated at t = –0.2. At this time, the shock wave is moving to the left.
Fig. 2
Guderley density solution (k = 2, γ = 1.4, ρ0 = 1.0) as a function of r, evaluated at t = 0.2. At this time, the shock wave is moving to the right.
Fig. 3
Direct initialization of a similarity solution onto a computational spatial grid
Fig. 4
Piston initialization of a similarity solution onto a computational spatial grid
Fig. 5
Piston velocity versus time for the Guderley problem (k = 2, γ = 1.4)
Fig. 6
Piston trajectory (solid line) for the Guderley problem (k = 2, γ = 1.4), with initial condition given by Eq. (41). The dashed line denotes the shock trajectory.
Fig. 7
Guderley problem (k = 2, γ = 1.4) density simulation results for direct (top) and piston (bottom; the right edge of this plot denotes the piston location) initialization methods; t = –0.2 (converging shock)
Fig. 8
Guderley problem (k = 2, γ = 1.4) density simulation results for direct (top) and piston (bottom; the right edge of this plot denotes the piston location) initialization methods; t = –0.2 (diverging shock)
Fig. 9
Guderley problem (k = 2, γ = 1.4) density error simulation results for direct (top) and piston (bottom; the right edge of this plot denotes the piston location) initialization methods; t = –0.2 (converging shock)
Fig. 10
Guderley problem (k = 2, γ = 1.4) density error simulation results for direct (top) and piston (bottom; the right edge of this plot denotes the piston location) initialization methods; t = 0.2 (diverging shock)
Fig. 11
Guderley problem (k = 2, γ = 1.4) L1 error convergence results for shock position (rs) and magnitude (Ms). Clockwise from top left: rs at t = –0.2 (converging shock), rs at t = 0.2 (diverging shock), Ms at t = 0.2 (diverging shock), Ms at t = –0.2 (converging shock). Fit data are summarized in Tables 5 and 6.
Fig. 12
Guderley problem (k = 2, γ = 1.4) mass-weighted L1 error norm convergence results for flow variables. Clockwise from top left: direct method at t = –0.2 (converging shock), piston method at t = –0.2 (converging shock), piston method at t = 0.2(diverging shock), and direct method at t = 0.2 (diverging shock). Fit data are summarized in Tables 11 and 12.
Fig. 13
Piston velocity (top) and trajectory (bottom) for the Caramana–Whalen–Shashkov Guderley problem (k = 2, γ = 5/3). Solid lines result from an exact solution of Eqs. (28)(30), and (39) with 1/λ = 0.6883545, t0 = 0.75, and xs = –0.75; dashed lines result from use of Eq. (A1).
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• EMAIL: asmedigitalcollection@asme.org | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8184992074966431, "perplexity": 5544.734159429424}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-26/segments/1529267860041.64/warc/CC-MAIN-20180618031628-20180618051628-00483.warc.gz"} |
https://math.stackexchange.com/questions/2711149/can-you-write-something-like-3-cdot5-cdot7-cdots2n1-as-2n1 | # Can you write something like $3\cdot5\cdot7\cdots(2n+1)$ as $(2n+1)!$?
I have been working through some infinite series in calculus I, and there have been a lot of expressions of the form $a\cdot b\cdot c\cdots(zn+x)$. It usually seems to work if I simplify them to $(zn+x)!$. In addition to the example I gave in the question, here are a couple more:
1. $2\cdot3\cdot4\cdots(n+1) = (n+1)!$
2. $1\cdot2\cdot3\cdots(2n-1) = (2n-1)!$
However, my professor said that this was incorrect and that she had an explanation for why, but for some reason, it slipped her mind. It seems like my textbook does not simplify them like I do either, but I still do not understand what is mathematically wrong with doing it like that.
Any help would be much appreciated!
-Isaac
Edit:
Thanks for your comments. I see that I am clearly overthinking this, and I'm sure that something will click into place once I read through what you all said several times more. However, I still don't really get it. Isn't
$(n+1)! = (n+1)\cdot(n)\cdot(n-1)\cdot\cdots\cdot(n-(n-1))$?
How is this not the same as
$(n+1)! = 2\cdot3\cdot4\cdot\cdots\cdot(n+1)$?
Do I have to specify that n is an integer greater than 1 for it to work, or is there something more fundamentally wrong?
I'm not trying to waste anyone's time; this is honestly something that I am confused about. I enjoy my math class, and I want to really get what I am learning.
Also, thanks for posting that MathJax tutorial. I was trying to figure it out earlier, but I think I've got it now.
One last note: my original post had a typo in example 2. It is fixed now.
• So for instance, is $1\times 3\times5\times 7$ equal to $7!$? Of course $7!=5040$, a nice even number. – Lord Shark the Unknown Mar 28 '18 at 1:15
• It's simply wrong. Make a substitution $2n-1=k$ then consider $k!$ and compare to your product – Yuriy S Mar 28 '18 at 1:15
• If you want to say "although usually the expression $n!$ means the product of all natural numbers up to $n$, for the purpose of this paper, I'll be using it to mean 'go make a peanut butter sandwich'", you may. But you will have to expect no-one in any other context to know what you mean. $(zn+x)!$ simply does mean $1*2*...*(zn+x-1)*(zn+x)$ and it simply doesn't mean $(z+x)(2z+x)... (zn+x)$. But if you want to SAY it does, go ahead. But just make sure you explicitly state it, and you only use it in that one context. – fleablood Mar 28 '18 at 3:06
• The OEIS is frequently a very useful resource for math. For this particular question, look at oeis.org/A001147 and oeis.org/A000165 – Robert Soupe Mar 28 '18 at 3:34
I think you are looking for the product notation.
$$\prod_{i=1}^n (2i-1)= 1\cdot 3\cdot 5 \ldots (2n-1)=\frac{(2n-1)!}{2\cdot 4\cdot \ldots (2n-2)}=\frac{(2n-1)!}{(n-1)!2^{n-1}}$$
$$\prod_{i=1}^n (i+1)= 2\cdot 3\cdot 4 \ldots (n+1)=(n+1)!$$
$$\prod_{i=1}^n (zi+x)= (z+x)\cdot(2z+x)\cdot \ldots \cdot(nz+x)$$
The factorial notation $n!$ multiply every positive integers up to $n$.
• That's right, I forgot about product notation. I really appreciate your comment, I understand much better now – Ii Meme Mar 29 '18 at 2:01
The equation
$$1 \cdot 3 \cdot 5 \cdot \ldots \cdot (2n-1) = (2n-1)!$$
is (usually) wrong because, by definition,
$$(2n-1)! = 1 \cdot 2 \cdot 3 \cdot \ldots \cdot (2n-1)$$
and we (usually) have
$$1 \cdot 3 \cdot 5 \cdot \ldots \cdot (2n-1) \neq 1 \cdot 2 \cdot 3 \cdot \ldots \cdot (2n-1)$$
The specific example you give, incidentally, comes up often enough to be given a name: the double factorial. It has different definitions depending on whether it is even or odd:
$$(2n-1)!! = 1 \cdot 3 \cdot 5 \cdot \ldots \cdot (2n-1)$$ $$(2n)!! = 2 \cdot 4 \cdot 6 \cdot \ldots \cdot (2n)$$
There are convenient identities
$$n! = n!! \cdot (n-1)!!$$ $$(2n)!! = 2^n n!$$
• In case it's not clear, $!!$ is meant to be read as a single symbol. $n!!$ means to apply the double factorial operation to $n$; it does not mean to apply the factorial and then apply the factorial a second time. That is, we usually have $n!! \neq (n!)!$. – Hurkyl Mar 28 '18 at 1:32
• I did not know about the double factorial, thanks for letting me know. About that example I gave, that was a typo on my part. I will edit it to display what it should. – Ii Meme Mar 29 '18 at 2:12
"but I still do not understand what is mathematically wrong with doing it like that."
Seriously?
You don't see why $1*2*3*4*5*6*7* ......(2n-3)*(2n-2)*(2n-1)*(2n)*(2n + 1) \ne 1*3*5*7*.......... *(2n-3)*(2n-1)*(2n+1)$?
Only one of those can be written as $(2n+1)!$. Which one is it going to be?
Oh, you chose the RHS...? Well, I wasn't actually giving you a choice. The question was first asked 80 years ago and everyone chose the LHS.
"However, my professor said that this was incorrect and that she had an explanation for why, but for some reason, it slipped her mind."
Seriously?!?!?
• Part of me thinks this may be a troll question. – Crescendo Mar 28 '18 at 4:47
• Thanks for responding to my question. It was indeed serious; I legitimately did not know. Also, my tutor said that it was correct, I posted this question to figure out who was right. Have a nice day – Ii Meme Mar 29 '18 at 1:56 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8201767802238464, "perplexity": 282.1495288701884}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-39/segments/1568514574182.31/warc/CC-MAIN-20190921022342-20190921044342-00136.warc.gz"} |
https://www.gurobi.com/documentation/9.1/examples/gc_pwl_func_py.html | # gc_pwl_func.py
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### gc_pwl_func.py
#!/usr/bin/env python3.7
# Copyright 2021, Gurobi Optimization, LLC
# This example considers the following nonconvex nonlinear problem
#
# maximize 2 x + y
# subject to exp(x) + 4 sqrt(y) <= 9
# x, y >= 0
#
# We show you two approaches to solve this:
#
# 1) Use a piecewise-linear approach to handle general function
# constraints (such as exp and sqrt).
# u = exp(x)
# v = sqrt(y)
# b) Compute points (x, u) of u = exp(x) for some step length (e.g., x
# = 0, 1e-3, 2e-3, ..., xmax) and points (y, v) of v = sqrt(y) for
# some step length (e.g., y = 0, 1e-3, 2e-3, ..., ymax). We need to
# compute xmax and ymax (which is easy for this example, but this
# does not hold in general).
# c) Use the points to add two general constraints of type
# piecewise-linear.
#
# 2) Use the Gurobis built-in general function constraints directly (EXP
# and POW). Here, we do not need to compute the points and the maximal
# possible values, which will be done internally by Gurobi. In this
# approach, we show how to "zoom in" on the optimal solution and
# tighten tolerances to improve the solution quality.
#
import math
import gurobipy as gp
from gurobipy import GRB
def printsol(m, x, y, u, v):
print('x = ' + str(x.x) + ', u = ' + str(u.x))
print('y = ' + str(y.x) + ', v = ' + str(v.x))
print('Obj = ' + str(m.objVal))
# Calculate violation of exp(x) + 4 sqrt(y) <= 9
vio = math.exp(x.x) + 4 * math.sqrt(y.x) - 9
if vio < 0:
vio = 0
print('Vio = ' + str(vio))
try:
# Create a new model
m = gp.Model()
# Create variables
# Set objective
m.setObjective(2*x + y, GRB.MAXIMIZE)
lc = m.addConstr(u + 4*v <= 9)
# Approach 1) PWL constraint approach
xpts = []
ypts = []
upts = []
vpts = []
intv = 1e-3
xmax = math.log(9)
t = 0.0
while t < xmax + intv:
xpts.append(t)
upts.append(math.exp(t))
t += intv
ymax = (9.0/4)*(9.0/4)
t = 0.0
while t < ymax + intv:
ypts.append(t)
vpts.append(math.sqrt(t))
t += intv
gc1 = m.addGenConstrPWL(x, u, xpts, upts, "gc1")
gc2 = m.addGenConstrPWL(y, v, ypts, vpts, "gc2")
# Optimize the model
m.optimize()
printsol(m, x, y, u, v)
# Approach 2) General function constraint approach with auto PWL
# translation by Gurobi
# restore unsolved state and get rid of PWL constraints
m.reset()
m.remove(gc1)
m.remove(gc2)
m.update()
# u = exp(x)
# v = x^(0.5)
gcf2 = m.addGenConstrPow(y, v, 0.5, name="gcf2")
# Use the equal piece length approach with the length = 1e-3
m.params.FuncPieces = 1
m.params.FuncPieceLength = 1e-3
# Optimize the model
m.optimize()
printsol(m, x, y, u, v)
# Zoom in, use optimal solution to reduce the ranges and use a smaller
# pclen=1-5 to solve it
x.lb = max(x.lb, x.x-0.01)
x.ub = min(x.ub, x.x+0.01)
y.lb = max(y.lb, y.x-0.01)
y.ub = min(y.ub, y.x+0.01)
m.update()
m.reset()
m.params.FuncPieceLength = 1e-5
# Optimize the model
m.optimize()
printsol(m, x, y, u, v)
except gp.GurobiError as e:
print('Error code ' + str(e.errno) + ": " + str(e))
except AttributeError:
print('Encountered an attribute error') | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5589839220046997, "perplexity": 16591.902303603092}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-43/segments/1634323588284.71/warc/CC-MAIN-20211028100619-20211028130619-00439.warc.gz"} |
https://www.forex.academy/alternation-and-extensions-in-the-wave-analysis-advanced-level/?replytocom=7756 | Home Forex Technical Analysis Forex Elliott Wave Alternation and Extensions in the Wave Analysis – Advanced Level
Alternation and Extensions in the Wave Analysis – Advanced Level
299
1
Introduction
In previous articles, we discussed the concepts of alternation and extensions and their importance in wave analysis.
R.N. Elliott, in his work “The Wave Principle,” described alternation as a principle of nature. Likewise, since financial markets are the result of human activity, and consequently part of nature, they are governed by the “law of nature.”
Elliott also identified the existence of extensions as part of impulsive movements. In particular, in his Treatise, Elliott points out that extensions should appear only on one of the three motive waves and never on more than one.
In this educational article, we will review and expand on the concepts of Alternation and Extensions applied in wave analysis.
Alternation
As we have seen in previous articles, alternation can be recognized in different forms, which are detailed as follows:
1. Price, which corresponds to vertical advance, either increasing or decreasing.
2. Time, which corresponds to the time taken by the construction of each wave.
3. Severity, which is the ratio of the wave to the impulsive pattern, this aspect applies only to corrective waves 2 and 4.
4. Complexity, which refers to the number of subdivisions that the Elliott pattern has in development.
5. Construction, an Elliott wave pattern, can be a flat, zigzag, triangle, etc.
So far, we have studied the characteristics of alternation in the first three aspects.
In impulsive structures, they can alternate in terms of time and price. However, in corrective structures, alternation in terms of price is usually not relevant.
However, on alternation in time, in particular, one must verify the time taken by each phase of the corrective pattern, which in general will be very different from each other. Likewise, in terms of severity, if a corrective wave produces a deep retrace to the previous impulsive wave, likely, the next corrective wave will not show a deep retrace and vice versa.
The next aspect that corresponds to the alternation principle is complexity or intricacy, which refers to the number of internal subdivisions that have an Elliott wave pattern, compared to the number of subdivisions that have the adjacent structure.
In practical terms, it will be useful for the analysis of poly-waves and multi-waves. In this way, it will be helpful for one wave to be subdivided and the other not.
The following figure shows cases for impulsive and corrective structures.
The alternation in terms of construction corresponds to the patterns that compose an impulsive or corrective structure.
For example, in a corrective sequence in which the first movement is composed of a zigzag pattern, the next corrective move can be any structure, minus a zigzag.
In this context, in the real market, a typical sequence is first the appearance of a zigzag and then a movement corresponding to a flat pattern, as shown in the following figure. Likewise, if the price action develops an impulsive structure, the next movement will correspond to a corrective structure of the same degree.
Extensions
Usually, in wave analysis, the extension and subdivision concepts tend to be used interchangeably. However, Glenn Neely, in his work “Mastering Elliott Wave,” shows that both terms are independent.
On the one hand, the extension corresponds to the wave with the longest movement in favor of the trend. As we have seen in previous articles, the extended wave appears in a single wave, and this may be in the first, third, or fifth wave, but it will never be present in more than one simultaneously.
On the other hand, the term subdivision applies to the number of segments constituting a wave, which can be impulsive or corrective.
Thus, the extended wave will not necessarily be the one with the most subdivisions. Likewise, as the complexity of the wave under study increases, the level of subdivisions that constitute it will also increase.
Finally, as indicated by R.N. Elliott in his Treatise, the extended wave is a relevant factor in terms of the behavior of an impulsive wave, either by what the most complex corrective wave will be. It can also lead the wave analyst to avoid losses and obtain gains from its knowledge.
When the first wave is extended, the structural sequence has a wedge shape. In this series of waves, the ends of waves 1 and 3 and waves 2 and 4 are joined. Usually, the fifth wave will end up under the higher guideline. The structure shall be complete when the price action violates the lower guideline joining waves 2 and 4.
When the third wave is the extended one, the fourth wave should not retrace beyond 38.2% of the third wave advance. If the retrace extends beyond 38.2%, this would be indicative of a weakness in impulsive movement, and consequently, the fifth wave should not reach a new high.
Finally, when the fifth wave is the most widespread, waves 1 and 3 may be similar, the third wave being slightly longer than the first and the fourth wave the most complex corrective wave compared to the second wave. The fifth wave will have the appearance of a false rupture of the directive that joins waves 1 and 3.
Conclusions
In this educational article, we have seen the importance of the principle of alternation in wave analysis, which can provide valuable information in the study of price action.
Also, knowledge of the alternation principle can help the wave analyst to identify which wave will be extended. In particular, when the analysts look to incorporate to the trend when it is in progress.
In the next educational article, we will study the process of wave counting and counting. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8727402687072754, "perplexity": 844.6957122706532}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-49/segments/1637964358903.73/warc/CC-MAIN-20211130015517-20211130045517-00559.warc.gz"} |
https://www.physicsforums.com/threads/simple-but-poorly-worded-unit-conversion-question.332750/ | # Simple but poorly worded unit conversion question
1. Aug 26, 2009
### dvs0826
1. The problem statement, all variables and given/known data
Because Earth's rotation is gradually slowing, the length of each day increases: The day at the end of 1.0 century is 1.0 ms longer than the day at the start of the century. In 54 centuries, what is the total (in hours) of the daily increases in time (that is, the sum of the gain on the first day, the gain on the second day, etc.)?
2. Relevant equations
Sum of an arithmetic sequence (see below)
3. The attempt at a solution
I've seen this question "answered" a number of times via a google search (for example, https://www.physicsforums.com/showthread.php?t=208510"), but nobody seems to ask the more fundamental question: What are they even asking? Most attempts at answering the question use an arithmetic sequence. For example, if the day is 1ms longer at the end of each century, then at the first day it was 1/36525 ms (365.25 days/year, 100 years/century) longer than at the beginning of the first century, and at the second day it was 2/36525 ms longer than at the beginning of the first century, and more generally at the n'th day it was n/36525 ms longer than at the beginning of the first century. So the sum of all these gains is (1 + 2 + 3 + ... + k) / 36525, where k is the total number of days in 54 centuries.
I have three problems with all of these solutions.
First of all, it makes no sense. The answer you get is meaningless in the context of physics and has no physical interpretation that I can come up with. This is normal in a math book to have problems with no physical interpretation, but I'm suspicious of seeing a physics problem like this.
Second, I'm not sure what this formula is that people are using for the sum of an arithmetic sequence. In the link above, for example, someone claims that the sum is (n/2) · [2·a1 + (n-1)·d]. What are a1 and d? And what happened to n*(n+1) / 2?
Third, the wording of the question says "what is the total (in hours) of the daily increases in time". The daily increases. The increases between each day. The increases between each day are constant, 1/36525 ms. So the sum of the daily increases for a century should be 1ms, and the sum of the daily increases for 54 centuries should be 54 ms, or 1.5 × 10^-5 hours.
Anyone have any insight on what the heck this question is talking about?
Thanks
Last edited by a moderator: Apr 24, 2017
2. Aug 26, 2009
### Fightfish
A term in an arithmetic sequence is given by $$u_{n} = a + (n-1) d$$.
a is the constant base term, while d is the common difference between consecutive terms.
The $$\frac{n(n+1)}{2}$$ that you cite is only true for the sum 1+2+3+...n, which would constitute an arithmetic sequence $$u_{n} = 1 + (n-1) (1) = n$$. Substituting a and d = 1 into the general formula thus yields $$\frac{n(n+1)}{2}$$.
3. Aug 26, 2009
### dvs0826
Ahh, I'm always bad at remembering formulas. I tend to just stick with a single formula whenever possible and then just massage everything into the right format to make it work.
Thanks, now just looking for any suggestions on the problem itself
4. Aug 26, 2009
### senan
As I read the question I just see it as your 3rd point. The sum of the gain of each of the days is simply 54ms. As the question gives you the increase per century independent of the length of the day I don't see why you are involving sumations at all. The increase per century is 1ms independent of the lenght of the day during the century as I see it.
5. Aug 26, 2009
### ideasrule
I'm pretty sure I know what it means.
Suppose you have a cesium atomic clock that can keep time much better than Earth's rotation. (Actually, you don't have to suppose; they exist.) After 54 centuries, the clocks will say that the time is such-and-such. Because Earth's rotation has been slowing down, astronomical observations will indicate a different time. The clocks might say that it's noon in England, for example, even though the Sun has yet to rise. The question asks: what is the difference between the clock's time and the time determined by Earth's rotation?
This question is extremely meaningful because it turns out that the slowing of Earth's rotation is more than detectable with atomic clocks. Every few years, a "leap second" is added to the time to compensate for decreases in the length of the day. Many effects contribute to the decrease: the most significant are tidal interactions with the Moon and glacier rebound, but other effects are of a similar order of magnitude. That's why leap seconds don't get inserted at regular intervals: because Earth's rotation is not slowing at a constant rate. However, for this question, you have to assume that it is; you'll be able to get a reasonably accurate answer because the extremely regular tides generated by the Moon dominate other factors.
If you're interested, you can read http://tycho.usno.navy.mil/leapsec.html [Broken] for a more detailed explanation of the leap seconds that inspired your question.
About the question itself: using the arithmetic series formula is only an approximation, but it's more than accurate enough considering the uncertainty in the rate that Earth's rotation slows. What you're assuming is that Earth rotates at exactly the same rate for one revolution, then instantly changes its rotation speed and rotates exactly 1 revolution at the new speed, then repeats the process. In reality, rotation speed is slowing constantly and not just at year-end, and to rigorously account for that you'd have to use integration. For this problem, integration happens to be easier. Suppose you have a small period of time dt. After time t, dt has lengthened by ktdt, where k is 1 ms/century. Its length would then be (1+kt)dt. Integrating that gives t+kt2/2, so kt2/2 would be the time difference between real time and solar time.
Last edited by a moderator: May 4, 2017
6. Aug 26, 2009
### dvs0826
I actually agree with you, but myself and a friend both solved the problem independently, and I did it the 54ms way, and he did it the summation way. Neither of us could understand why the other was doing it the way they did, so we searched on google and found many "solutions" to the problem. Almost all used the summation way, which is really strange to me. I guess this was why I got my undergrad degree in math, so I dont' have to worry about lack of precision in the wording of problems :)
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Accepted : 2/1/2016 2:56:00 PM
Abstract :
In this note, we propose the minimal representation of an element in a quasi-modular pseudocomplemented lattice (PCL) satisfying the descending chain condition generalizing of the result of Ji and Xin for modular PCLs. We prove that the minimal representation of an element is unique. Necessary and sufficient conditions are given under which a sequence of positive integers can be the spectrum of a quasi-modular PCL. An alternative proof is presented following Katrinaks work. These results settle the problems raised by Gratzer, Gungerson and Quackenbush in 2009, in case of quasi-modular PCLs which form a larger class that contains the modular one. Finally, we characterize the spectrum of a finite quasi-modular S-algebras.
Ref : 253
Title : Parameter estimation in metabolic control analysis in enzyme kinetic systems
Author(s) :
Name : Mustafa Bayram Address : Department of Healthcare Management, Uskudar university, Istanbul, Turkey
Accepted : 2/1/2016 12:26:00 AM
Abstract :
Determination of enzyme kinetic parameters has traditionally been made by isolating individual enzymes in vitro and performing initial rate experiments.
It is possible to write down the equations governing a one-stageenzyme-catalysed reaction (according toMichaelis–Menten kinetics) quite easily, and deduce information about the steady-state flux in such a system. The situation is some what more complicated if several such reactions form a linear chain. A procedure for fitting enzyme kinetic data directly to the flux equation was described. It involves choosing parameters that minimize the sum of the squares of deviations due to errors in s, the substrate concentration at time t. Estimates of the standard errors of the parameters are provided using computer algebra and numerical analysis techniques.
Ref : 252
Title : Influence of Bi-doped TiO2 layer on the performance of dye-sensitized solar cells
Author(s) :
Name : Alshimaa Ali Address : Department of Physics, Faculty of Science, Menoufia University, Egypt.
Name : Ahmed Alhamalawy Address : Department of Physics, Faculty of Science, Menoufia University, Egypt.
Name : Meawad Elkholy Address : Department of Physics, Faculty of Science, Menoufia University, Egypt.
Accepted : 2/1/2016 12:26:00 AM
Abstract :
A new method to prepare Bi-doped TiO2 pastes with different ratios was used to obtain dye sensitized solar cells(DSSCS).TiO2 powder was derived from home- made TiO2 nano-particles. The crystalline size of Bi-doped TiO2,strain and lattice distortion were calculated. The samples were characterized by X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX). Photovoltaic behavior of dye sensitized solar cells prepared by Bi-doped TiO2 was studied.
Ref : 251
Title : Oscillation of Fractional Order Functional Differential Equations With Nonlinear Damping
Author(s) :
Name : Hakan Adiguzel Address : Department of Mathematical Engineering, Faculty of Chemistry-Metallurgical, Yildiz Technical University, Istanbul, Turkey
Name : Mustafa Bayram Address : Department of Mathematical Engineering, Faculty of Chemistry-Metallurgical, Yildiz Technical University, Istanbul, Turkey
Name : Suleyman Ogrekci Address : Department of Mathematics, Sciences&Arts Faculty, Amasya University, Amasya, Turkey
Accepted : 1/29/2016 2:43:00 PM
Abstract :
In this paper, we are concerned with the oscillatory behavior of a class of fractional
differential equations with functional terms. The fractional derivative defined in the sense of
the modified Riemann-Liouville derivative. Based ona a certain variable transformation, by
using generalized Riccati transformation, Generalized Philos type kernels and averagaging
technique we establish new interval oscillation criteria. Illustrative examples also given.
Ref : 250
Title : Oscillation Criteria for A class of Fractional Order Functional Differential Equation with Nonlinear Damping Term
Author(s) :
Name : Aydin Secer Address : Department of Mathematical Engineering, Faculty of Chemistry-Metallurgical, Yildiz Technical University, Istanbul, Turkey
Name : Mustafa Bayram Address : Department of Mathematical Engineering, Faculty of Chemistry-Metallurgical, Yildiz Technical University, Istanbul, Turkey
Name : Hakan Adiguzel Address : Department of Mathematical Engineering, Faculty of Chemistry-Metallurgical, Yildiz Technical University, Istanbul, Turkey
Accepted : 1/29/2016 2:43:00 PM
Abstract :
In this paper, we are concerned with the oscillations in a class of fractional order funtional differential equation with nonlinear damping term. By generalized Riccati transformation and inequality technique, some new oscillation criteria for the equations are obtained
Ref : 248
Title : Oscillation of Solutions to Nonlinear Fractional Differential Equation with Damping Term
Author(s) :
Name : Hakan Adiguzel Address : Department of Mathematical Engineering, Faculty of Chemistry-Metallurgical, Yildiz Technical University, Istanbul, Turkey
Name : Mustafa Bayram Address : Department of Mathematical Engineering, Faculty of Chemistry-Metallurgical, Yildiz Technical University, Istanbul, Turkey
Name : Aydin Secer Address : Department of Mathematical Engineering, Faculty of Chemistry-Metallurgical, Yildiz Technical University, Istanbul, Turkey
Accepted : 1/29/2016 2:44:00 PM
Abstract :
In this study, we study the oscillation of solutions to a nonlinear fractional differential equation with damping term. The fractional derivative is defined in the sense of the modified Riemann-Liouville derivative. Based on a certain variable transformation, by using a generalized Riccati transformation, inequality, and integration average technique, we establish new oscillation criteria. Several illustrative examples are also given.
Ref : 247
Title : On Slightly G-Precontiuous functions
Author(s) :
Name : A. A. AZZAM Address : Department of Math. Faculaty of science, Assuit university, New Vally
Accepted : 1/29/2016 2:45:00 PM
Abstract :
In this paper a new class of functions called slightly G-precontinuous functions has been de ned and studied Grill topological spaces. Some characterization and several basic properties of this class of functions are obtained.
AMS Mathematics Subject Classi cation: (2000) 54A05, 54C10.
Keywords and Phrases: Grill topological space, G-preopen sets, Slightly
G-precontinuty.
1
Ref : 245
Title : Management of Quantum Databases
Author(s) :
Name : M A. A. Zidan, Abdel-Haleem Abdel-Aty Address : Physics Department, Faculty of Science, Al-Azhar University, Assiut , Egypt
Accepted : 1/25/2016 3:30:00 PM
Abstract :
Databases is the essential entity for building quantum operating systems. In this paper we propose a novel quantum algorithm to perform manipulation of quantum databases based on the unique properties of quantum information and computation such as superposition and entanglement.
Ref : 244
Title : EKNN: Ensemble Classification by Incorporating Connectivity and Density into KNN Applied to Genetic Cancer Diagnosis
Author(s) :
Name : Mohamed A. Mahfouz Address : 300, Gamal Abdelnaser St., Alexandria, Miami
Accepted : 1/25/2016 3:56:00 AM
Abstract :
Microarray based approach for automated diagnostic of cancer has been used in various research studies. By analyzing the gene expression deviation from its normal composition, classification algorithms are able to assign cancer grades to incoming sample. In this study, a novel ensemble classification scheme relative to the famous K-Nearest Neighbors algorithm (KNN) is proposed. The proposed algorithm (EKNN) exploits the increase in connectivity and density in classifying gene samples into normal and malignant classes. Novelty of EKNN is in two complementary ways. First, an efficient dimension reduction technique based on graph coloring is proposed and compared to two state of the art dimension reduction techniques. Second, a majority based ensemble of two novel classification models, beside the traditional k-nearest-neighbors, has been proposed. In the first model, the incoming pattern is classified as class t if class t achieves the highest increase in density if this pattern is added to it. In the second model, the class that achieves the highest reduction in the average distance of the k neighbors of its members when the incoming pattern is added to it, is chosen. Combining the predicted results of individual models makes the decision space more discriminative. The proposed technique has been tested on several datasets. An improved performance has been achieved compared to the traditional KNN algorithm and previously reported gene based cancer detection techniques.
Keywords: Cancer Diagnosis , Ensemble Classification, Gene Expressions, Dimension Reduction
Ref : 243
Title : Dynamical analysis of fractional-order biological model and its discretization
Author(s) :
Name : A. A. Elsadany Address : Department of Basic Science, Faculty of Computers and Informatics, Ismailia 41522, Suez Canal University, Egypt
Accepted : 1/22/2016 10:09:00 AM
Abstract :
In this work, we study some dynamical behaviors in the fractional-order Lotka-Volterra system. We investigate the stability conditions in the system. Also, the analytical conditions of stability of the discretized system are studied. Furthermore, chaotic behaviors in the discretized system are obtained. It is shown that the discretized system exhibits much richer dynamical behaviors than its corresponding
fractional-order form; in the discretized system, many types of bifurcation and chaos are obtained however the dynamics of fractional-order counterpart is included only stable (unstable) equilibria.
Ref : 242
Title : On the Optimal Control for MultiStrain TB Models
Author(s) :
Name : Nasser H. Sweilam Address : Cairo University, Faculty of Science, Mathematics Department, Giza, Egypt
Accepted : 1/21/2016 9:34:00 AM
Abstract :
In this paper, optimal control of a general nonlinear multi-strain TB model which incorporates three strains: drug-sensitive, emerging multi-drug resistant(MDR) and extensively drug-resistant(XDR) is presented. The general multi-strain TB model is introduced as a fractional-order multi-strain TB model. The fractional derivatives are described in the Caputo sense. An optimal control problem is formulated and studied theoretically using the Pontryagin maximum principle. Four controls variables are proposed to minimize the cost of interventions. Two simple numerical methods are used to study the nonlinear fractional optimal control problem (FOCP). The methods are, the iterative optimal control method (IOCM) and the generalized Euler method (GEM). Comparative studies are implemented, it is found that IOCM method is better than GEM
Ref : 241
Title : AVLINK: Robust Clustering Algorithm based on Average Link Applied to Protein Sequence Analysis
Author(s) :
Name : Mohamed A. Mahfouz Address : 300, Gamal Abdelnaser St., Alexandria, Miami
Accepted : 1/21/2016 9:34:00 AM
Abstract :
Abstract— Robust Clustering methods are aimed at avoiding unsatisfactory results resulting from the presence of certain amount of outlying observations in the input data of many practical applications such as biological sequences analysis or gene expressions analysis. This paper presents a fuzzy iterative algorithm based on average link termed as AVLINK that maximizes the average similarity between pairs of patterns within the same cluster and at the same time the size of a cluster is maximized by computing the zeros of the derivative of appropriate objective function. The proposed algorithm is comprised of a judicious integration of the principles of Average link and possibilistic clustering paradigm. This integration enables robust selection of the minimum set of the most informative bio-bases from the lower bound of the produced clusters. AVLINK along with the proposed initialization procedure with a few less sensitive input parameters shows a high outliers rejection capability as it makes their membership very low furthermore it does not requires the number of clusters to be known in advance and it can discover clusters of non convex shape. The effectiveness and robustness of the proposed algorithms, along with a comparison with other algorithms, have been demonstrated on different types of protein data sets.
Ref : 240
Title : Fifty Years of Hoare Sorting Algoritms: A Global Stochastic View of the Quicksort Techniques
Author(s) :
Name : Mahmoud Ragab Address : Mathematics Department, Faculty of Science, Al Azhar University, Nasr City (11884), Cairo, Egypt.
Accepted : 1/21/2016 1:34:00 AM
Abstract :
Quicksort was chosen as one of the 10 most important algorithms. Quick-sort serves also as a challenging random divide-and-conquer algorithm for a mathematical analysis. We focus here on the average cost of a special version of the Quicksort algorithm, depending on the choice of the Pivot element. Starting with the worst case, the best case and the expected running time we know nowadays much finer results on the limiting distribution, the existence via martingale methods and a characterization as a stochastic fixed point. The running time for many versions, actually all versions I know of, can be analyzed by smart tools. focus here on the average cost of these algorithms, depending on the choice of the sample. We also present the Contraction method and Weighted Branching Process invented for Quicksort. Keywords and phrases: sorting algorithms, Quicksort, running time analysis, stochastic process.
Ref : 239
Title : Fifty Years of Hoare Sorting Algoritms: A Global Stochastic View of the Quicksort Techniques
Author(s) :
Name : Mahmoud Ragab Address : Mathematics Department, Faculty of Science, Al Azhar University, Nasr City (11884), Cairo, Egypt.
Accepted : 1/21/2016 1:34:00 AM
Abstract :
Quicksort was chosen as one of the 10 most important algorithms. Quicksort serves also as a challenging random divide-and-conquer algorithm for a mathematical analysis. We focus here on the average cost of a special version of the Quicksort algorithm, depending on the choice of the Pivot element. Starting with the worst case, the best case and the expected running time we know nowadays much finer results on the limiting distribution, the existence via martingale methods and a characterization as a stochastic fixed point.The running time for many versions, actually all versions I know of, can be analyzed by smart tools. focus here on the average cost of these algorithms, depending on the choice of the sample. We also present the Contraction method and Weighted Branching Process invented for Quicksort.
Ref : 237
Title : Recent developments on solving systems of coupled generalized Sylvester matrix equations using iterative algorithms
Author(s) :
Name : Mohamed Abdel-Latif Ramdan Address : Department of Mathematics, Faculty of Science,Menoufia University, Shebeen El- Kom, Egypt
Accepted : 1/19/2016 7:51:00 AM
Abstract :
Abstract
The problem of solving matrix equations has become a hot topic in the field of numerical linear algebra. In this talk, I will shed light on my recent contributions dealing with solutions of systems Sylvester matrix equations. Three main gradient based iterative techniques will be presented
The first technique is called a relaxed gradient based algorithm for solving extended Sylvester-conjugate matrix equations. In the second technique a modified gradient based algorithm for solving extended Sylvester- conjugate matrix equations is considered. The third technique is a recent suggested joint work and we called it an accelerated gradient based iterative algorithm for solving systems of coupled generalized Sylvester-transpose matrix equations.
.
Ref : 236
Title : Recent developments on solving systems of coupled generalized Sylvester matrix equations using iterative algorithms
Author(s) :
Name : Mohamed Abdel-Latif Ramadan Address : Department of Mathematics, Faculty of Science Menoufia University, Shebeen El- Koom, Egypt
Accepted : 1/19/2016 7:47:00 AM
Abstract :
The problem of solving matrix equations has become a hot topic in the field of numerical linear algebra. In this talk, I will shed light on my recent contributions dealing with solutions of systems Sylvester matrix equations. Three main gradient based iterative techniques will be presented. The first technique is called a relaxed gradient based algorithm for solving extended Sylvester-conjugate matrix equations. In the second technique a modified gradient based algorithm for solving extended Sylvester- conjugate matrix equations is considered. The third technique is a recent suggested joint work and we called it an accelerated gradient based iterative algorithm for solving systems of coupled generalized Sylvester-transpose matrix equations.
Ref : 235
Title : ON THE EVALUATION OF LEACH PROTOCOL FOR WSN
Author(s) :
Name : Soha Mohamed Hassan Address : Harbin, China
Accepted : 1/19/2016 7:48:00 AM
Abstract :
The design of WSN is an issue that is considered a challenge for routing protocol with energy efficiency. An effective way in sensor nodes is clustering that achieves energy efficiency. low energy adaptive clustering hierarchy (LEACH) protocol is the first and most efficient hierarchical cluster based routing protocol used in WSN to increase the lifetime of network. In this paper, we give a detailed simulation study of LEACH protocol. Using proposed enhancement which consider the distance between the non-head nodes and the cluster head nodes. We get more accurate analysis of energy consumption that can be scaled. Thus, the user can define more limitations on nodes usage for data transmission. Simulation results show that the proposed enhancement decrease energy consumption and lengthen the total lifetime of WSN compared to original LEACH.
Ref : 234
Title : ESTIMATIONS FOR CONSTANT PARTIALLY ACCELERATED LIFE TESTS FOR LINDLEY DISTRIBUTION BASED ON PROGRESSIVE TYPE-II SENSORING
Author(s) :
Name : Gamal A. Abd-Elmougod Address : Department of Mathematics, Faculty of Science, Taif University, Kingdom of Saudi Arabia
Name : Saher A. Awaji Address : Department of Mathematics, Faculty of Science, Taif University, Kingdom of Saudi Arabia
Accepted : 1/19/2016 7:48:00 AM
Abstract :
In this paper, the constant PALT applied to items whose life times under design condition are assumed to follows Lindley distribution under a progressive type II censoring. The likelihood equations of the involved parameters are derived and then reduced to a single nonlinear equation to be solved numerically to obtain the maximum likelihood estimates (MLEs) of the parameters. Approximate confidence intervals (CIs) for the parameters, based on normal approximation to the asymptotic distribution of MLEs, as well as the bootstrap confidence intervals are also proposed. The Bayes estimators are computed using the idea of MCMC methods to generate from the posterior distributions. A Monte Carlo simulation study is carried out to investigate the precision of the MLEs and to compare the performance of different corresponding confidence intervals considered. Finally, analysis of a simulated data set has also been presented for illustrative purposes.
Ref : 233
Title : PERFORMANCE EVALUATION OF PROACTIVE AND REACTIVE
Author(s) :
Name : Hamdy.H El-Sayed Address : Math Department - Faculty of Science- Sohag University-Egypt
Name : Marghny H.Mohamed Address : CS Dept., Faculty of computer and information, Assiut University, Egypt
Name : Mahmoud.A Mofaddel Address : Math Department - Faculty of Science- Sohag University-Egypt
Accepted : 1/17/2016 9:35:00 AM
Abstract :
A mobile ad hoc network (MANET) consists of mobile wireless nodes. The communication between these mobile nodes is carried out without any centralized infrastructure. MANET is a self-organized and self-configurable network where the mobile nodes move randomly. The mobile nodes act as router it can receive and forward packets. This type of networks has difficult to find a path between the communicating nodes because of limited resources and energy. Routing is the process of moving information across the network from source to destination. Routing is a critical issue in MANET and hence the focus of this paper on the performance of proactive and reactive routing protocols. We compared Optimized Link State Routing (OLSR) and Bee-Dijkstra Algorithm (BDA) using hop count, path cost, CPU time and delivery rate as a parameter with some network characteristics changes like topology changes, average number of neighbor nodes and node density. The study depicts that the BDA is more accurate than OLSR but OLSR protocol is particularly suitable for large and dense networks.
Ref : 232
Title : An efficient iterative method for solving Fredholm integral equations using Triangular functions
Author(s) :
Name : Mohamed A. Ramadan Address : Department of Mathematics, Faculty of Science, Menoufia University. Shbeen El-Koom,Egypt
Accepted : 1/17/2016 9:35:00 AM
Abstract :
In this paper the orthogonal triangular function (TF) based method is first applied to transform the Fredholm integral equations and Fredholm system of integral equations to a coupled systems of matrix algebraic equations. The obtained systems are a variant of coupled Sylvester matrix equations. A finite iterative algorithm is then applied to solve these systems to obtain the coefficients used to get the form of approximate solution of the unknown functions of the integral problems. Some numerical examples are solved to illustrate the accuracy and the efficiency of the proposed hybrid method. The obtained numerical results are compared with other numerical methods and the exact solutions.
Ref : 231
Title : Characterizing Solutions of Rough Programming Problem Based on A Boundary Function
Author(s) :
Name : H. G. Gomaa Address : Computer Science Institute, Suez, Egypt.
Accepted : 1/17/2016 2:19:00 AM
Abstract :
In this paper we introduce the concept of rough function based on a function of boundary region as well as the convexity and differentiability of rough function. Also a new kind of rough programming problem and its solutions are presented according to the notion of boundary function.
Ref : 230
Title : ESTIMATIONS FOR CONSTANT PARTIALLY ACCELERATED LIFE TESTS FOR LINDLEY DISTRIBUTION BASED ON PROGRESSIVE TYPE-II SENSORING
Author(s) :
Name : Gamal A. Abd-Elmougod Address : Department of Mathematics, Faculty of Science, Taif University, Kingdom of Saudi Arabia
Accepted : 1/16/2016 9:21:00 PM
Abstract :
In this paper, the constant PALT applied to items whose life times under design condition are assumed to follows Lindley distribution under a progressive type II censoring. The likelihood equations of the involved parameters are derived and then reduced to a single nonlinear equation to be solved numerically to obtain the maximum likelihood estimates (MLEs) of the parameters. Approximate confidence intervals (CIs) for the parameters, based on normal approximation to the asymptotic distribution of MLEs, as well as the bootstrap confidence intervals are also proposed. The Bayes estimators are computed using the idea of MCMC methods to generate from the posterior distributions. A Monte Carlo simulation study is carried out to investigate the precision of the MLEs and to compare the performance of different corresponding confidence intervals considered. Finally, analysis of a simulated data set has also been presented for illustrative purposes.
Ref : 229
Title : A critical review of physiological bubble formation in the bio tissues
Author(s) :
Name : Selim Ali Mohammadein Address : Department of Mathematics, Faculty of Science, Tanta University, Tanta, Egypt
Accepted : 1/16/2016 11:42:00 AM
Abstract :
The growth and collapse of Nitrogen gas bubbles in the bio tissues of Divers who surface too quickly to the sea level is obtained. The extended Mohammadein mathematical model is formulated by Fick, and concentration equations and solved analytically. The collapse operation is affected by tissue concentration diffusivity and void fraction. The concentration distribution surrounded the collapsing gas bubbles proportional with time and inversely with tissue concentration diffusivity. The collapse of gas bubble performs lower values in under water stage than after the end of decompression pressure stages. The model is used to study the harmful effects of the decompression sickness (DCS).
Ref : 227
Title : Analysis of Waveguides and Antennas
Author(s) :
Name : Mohamed Tarek ElHefnawy Address : 16A street 199 Degla - Maadi - Cairo
Accepted : 1/15/2016 1:57:00 PM
Abstract :
Waveguides assume many different forms that depend on the purpose of the guide and the waves to be transmitted. The simplest form is the parallel plate guide. Other forms are the hollow-pipe guides including the rectangular and circular guides. Dielectric waveguides used primarily at optical frequencies include slab waveguide and optical fibers. Each of these structures possesses certain advantages over the others depending on the application and the frequency of the waves to be transmitted. . In order to radiate EM waves efficiently in prescribed directions, the charges and currents must be distributed in specific ways. Antennas are structures designed for radiating EM energy in prescribed manner. Without an efficient antenna, EM energy would be localized. Maxwell’s equations govern the propagation of EM waves in all of these structures. Each structure and form has its own analysis. Analytical and numerical approaches can be investigated in various structures.
Ref : 226
Title : Effect of detuning on the dynamics of information for a non-Markovian regime
Author(s) :
Name : A.-S.F. Obada Address : Department of Mathematics, Faculty of Science, Al-Azhar University, Nasr City, Cairo, Egypt
Name : M.E. Shaheen Address : Department of Mathematics, Faculty of Science, Port Said University, Port Said, Egypt
Accepted : 1/15/2016 1:57:00 PM
Abstract :
Two qubits in two independent structured reservoirs or in a common structured reservoir with non-resonant interactions are considered. We study the effects of detuning on information and entanglement through temporal evolution of atomic quantum Fisher information and partial entropy of the qubit. The relationship between quantum Fisher information flow and quantum entanglement has been investigated.
Ref : 225
Title : Huffman compression algorithm
Author(s) :
Name : Mahmoud El-Sayed Abdelhammed Address : University of science and technology in ZewailCity
Accepted : 1/15/2016 1:58:00 PM
Abstract :
Abstract:
In this research, We are testing various prediction error techniques including linear and non linear methods and report how they affect the entropy and thus the compression ratio of compressed data based on the lossless compression algorithm Huffman source coding and block coding which is based on variable code lengths rather than the fixed code length of the ascii coding. Moreover, new combined techniques and multi-layer prediction error will be tested on different data which will be Images or alphabetical data in form of coded messages
Ref : 224
Title : Effect of detuning on the dynamics of information for a non-Markovian regime
Author(s) :
Name : A.-S.F. Obada Address : Department of Mathematics, Faculty of Science, Al-Azhar University, Nasr City, Cairo, Egypt
Accepted : 1/15/2016 1:58:00 PM
Abstract :
Two qubits in two independent structured reservoirs or in a common structured reservoir with non-resonant interactions are considered. We study the effects of detuning on information and entanglement through temporal evolution of atomic quantum Fisher information and von Neumman entropy of the qubit. We discuss the relationship between quantum Fisher information flow and quantum entanglement for the non-Markovian regime .
Ref : 223
Title : Shykon theory and heat transfer between two-phase flow (Postulates and Applications)
Author(s) :
Name : Selim Ali Mohammadein Address : 1Department of Mathematics, Faculty of Science, Tanta University, Tanta, Egypt
Accepted : 1/15/2016 1:58:00 PM
Abstract :
A new theory of heat is built on the basis of thermal elementary particles (Shykons). The postulates of the present theory have been applied to solve the heat exchange problem between two phase-flow. Temperature distribution surrounding a growing vapour bubble is obtained analytically. Thermal relaxation time is calculated in terms of void fraction and initial bubble velocity. The obtained results are compared with the previous published models and MOBY DICK experiment a good agreement. The obtain results in terms of shykon mass prove the validity of present theory(assumptions and application and real step the unified theory.
Ref : 222
Title : Application Decision Making-Based Scheme for Method Offloading in Mobile Cloud Computing Environments
Author(s) :
Name : Ahmed. A. A. Gad-ElRab Address : Department of Mathematics Faculty of Science Al-Azhar University, Cairo, Egypt
Name : T. A. A. Alzohairy Address : Department of Mathematics Faculty of Science Al-Azhar University, Cairo, Egypt
Name : Farouk. A. Emara Address : Department of Mathematics Faculty of Science Al-Azhar University, Cairo, Egypt
Accepted : 1/15/2016 1:58:00 PM
Abstract :
Ref : 221
Title : Growth of Vapour Bubbles Between Two-phase Bubbly Flow inside a Cylindrical Tube
Author(s) :
Name : A. K. Abu-Nab Address : Department of Mathematics, Faculty of Science, Menoufia University, Shebin El-Koom , Egypt
Name : S. A. Mohammadein Address : Department of Mathematics, Faculty of Science, Tanta University, Egypt
Accepted : 1/14/2016 1:42:00 PM
Abstract :
The growth of a vapour bubble in a superheated liquid in a cylindrical tube is studied. The problem is solved analytically using the modified method of Plesset and Zwick method. The pressure difference is described in terms of temperature difference. The growth of bubble radius is proportional with different physical parameters. The pressure distribution and flow velocities are obtained. Moreover, better agreements with some previous theoretical efforts.
Ref : 219
Title : Influences of Thermophoresis, Hall Currents and Heat Generation
Author(s) :
Name : A.R.Abd Al-Mohaimen (Ahmed Refaie Abd Al-Mohaimen) Address : Department of Mathematics, Faculty of science, Damietta University, New Damietta city, Egypt.
Name : N.T.M.Eldabe (Nabi Tawfeek Mohammed Eldabe) Address : Department of mathematics,Faculty of Education,Ain Shams University,Roxy,Heliopolis,cairo,Egypt
Name : A.A.El-shekhipy (Abdelhafeez Ahmed El-shekhipy) Address : Mathematics Department, Faculty of Science, Minia University, El-Minia, Egypt.
Accepted : 1/14/2016 8:10:00 AM
Abstract :
A mathematical model analysis has been developed to investigate the effect of thermophoresis on unsteady flow of Non-Newtonian fluid with heat and mass transfer over a vertical infinite porous plate through a porous medium.The fluid is obeying to a second grade model where its flow is permeated by a uniform strong magnetic field and so the hall currents are taken into the consideration .Also, The effects of thermal radiation , heat generation or absorption and thermal diffusion (soret effect) have been studied in the presence of viscous dissipation and chemical reaction. The problem is modulated mathematically by a system of coupled Non-linear partial differential equations which pertaining to describe the Continuity,Momentum,Energy and Concentration.The Numerical solutions of the resulting dimensionless equations are founded as a functions of the physical parameters of this problem .The field variables from the numerical computations ,dimensionless velocities u \& w ,temperature $\theta$ and concentration C profiles as well as the local skin -friction coefficient($C_f$) , the local Nusselt number($Nu$) and Sherwood number($Sh$) are obtained and illustrated graphically for different values of the physical parameters that is significant in this study.
Ref : 218
Title : Estimation of coefficient of variation Based on Adaptive Type-II Progressive Censoring
Author(s) :
Name : A. A. Soliman Address : Department of Mathematics, Sohag University, Sohag, Egypt, Department of Mathematics, Islamic University, Madinah, Saudi Arabia
Name : N. A. Abou-Elheggag Address : Department of Mathematics, Sohag University, Sohag, Egypt
Name : E. E. Ahmed Address : Department of Mathematics, Sohag University, Sohag, Egypt
Name : S. M. Ahmed Address : Department of Mathematics, Sohag University, Sohag, Egypt
Accepted : 1/14/2016 8:11:00 AM
Abstract :
In applied statistics, the coefficient of variation (CV) of a distribution is considered as one of the useful descriptive measures for describing variability. However, inferences concerning the coefficient of variation of non-normal distributions are rarely reported. In this paper, estimation of coefficient of variation using an adaptive Type-II progressive censored data for the Inverse Weibull distribution (IWD) is developed. A point estimates as well as interval estimates of CV are obtained using Bayesian and non-Bayesian approaches. In Bayesian approach, the joint prior density as a product of two independent gamma densities for the unknown (IWD) parameters is considered. In addition, Markov Chain Monte Carlo (MCMC) method to generate from the posterior distributions and computing the Bayes estimate is proposed.. A numerical example is provided to illustrate our proposed methods. Results from simulation studies assessing the performance of the maximum likelihood and Bayes estimates are included.
Ref : 217
Title : Three-dimensional blood vessel detection from low-dose CT imaging using shape prior approach
Author(s) :
Name : Esraa A. Mohamed Address : Department of Mathematics, Faculty of Science, Suez Canal University,Isamilia, Egypt
Name : Essam A. Rashed Address : Department of Mathematics, Faculty of Science, Suez Canal University,Isamilia, Egypt
Name : H. M. Hewedi Address : Department of Mathematics, Faculty of Science, Suez Canal University,Isamilia, Egypt
Accepted : 1/14/2016 12:16:00 PM
Abstract :
The identification of blood vessels is an important image processing technique in several medical imaging applications. Computed tomography (CT) is a common imaging modality used for blood vessels imaging. It can provide a high quality images for both diagnosis and treatment purposes. However, CT is known as a source of high radiation dose especially for cases required a follow up scans in short time. Reducing the CT dose is knows to produce statistical noise and artifacts that significantly reduce the image quality. In this paper, we propose a method for three-dimensional (3D) blood vessel detection from low-dose CT images. We employ a shape prior model to identify blood vessels as a post-processing step. The CT image reconstructed from low-dose projection data is used to identify the vessels using convex shape prior and morphological filters. Moreover, we develop a pixel connectivity model for 3D whole vascular network identification. The proposed method is tested for 3D blood vessel phantom and achieves superior results. It is also found that the proposed method is potentially useful in detecting lung airways.
Ref : 216
Title : Generalized Superposition of Squeezed Displaced Fock States
Author(s) :
Name : Norhan H. Gerish Address : Department of Mathematics, Faculty of Science, Suez Canal University,Isamilia, Egypt
Accepted : 1/14/2016 12:16:00 PM
Abstract :
The s-parametrized characteristic function for the superposition of squeezed displaced rock states is presented . the s-parametrized distribution function for superposition of SDFSs are investigated for different coherent state.The moments are obtained by using this characteristic function. The Glauber second-order correlation function is calculated. The squeezing properties of the superposition of SDFSs are studied. Analytical and numerical results for the quadrature component distribution for the superposition of pair of SDFSs are presented.
Ref : 215
Title : Solving of nonlinear fractional differential equations by using Mittage - Leffler method
Author(s) :
Name : S. Z. Rida Address : Dept. of Math., Faculty. of Science, Qina University
Name : Y. G. Gouda Address : Dept. of Math., Faculty of Science, Aswan University
Name : M. M. Farag Address : Dept. of Math. Faculty of Science, Aswan University
Accepted : 1/14/2016 12:16:00 PM
Abstract :
The fractional calculus plays an important role in many fields. It is considered as one of realistic modeling of a natural phenomenon that does not depend only on the instant time, but also on the history of the previous time which can be successfully achieved by using fractional calculus. In this article we use a Mittage – Leffler method to solve some problems of nonlinear differential equations with fractional order. The fractional derivatives are described in Caputo power series.
Ref : 214
Title : On Lyapunov Exponential Stability of Abstract First Order Dynamic Equations on Time Scales
Author(s) :
Name : Alaa E. Hamza Address : Cairo, Egypt
Accepted : 1/14/2016 3:51:00 AM
Abstract :
In this paper, we establish new sufficient conditions for the exponential stability of the abstract first order dynamic equation
{█(x^∆ (t)=F(t,x(t)), t∈T_τ^+≔[τ,∞)_T,@x(τ)=x_τ∈H,)┤
Where F:T×H→H is rd-continuous function in the first argument with F(t,0)=0, by using lyapunov functions technique. Here, H is a Hilbert space. Finally, we give an illustrative example
Ref : 212
Title : Hellinger Optimal Criterion and HP_A- Optimum Designs for Model Discrimination and Probability-Based Optimality
Author(s) :
Name : N. M. Kilany Address : Faculty of Science, Menoufia University, Egypt
Name : W. A. Hassanein Address : Faculty of Science, Tanta University, Egypt
Accepted : 1/14/2016 3:51:00 AM
Abstract :
Kullback-Leibler (KL) optimality criterion has been considered in the literature for model discrimination. However, Hellinger distance has many advantages rather than KL-distance. For that reason, in this paper a new criterion based on the Hellinger distance named by Hellinger (H) -optimality criterion is proposed to discriminate between two rival models. An equivalence theorem is proved for this criterion. Furthermore, a new compound criterion is constructed that possess both discrimination and a high probability of desired outcome properties. Discrimination between binary and Logistic GLM are suggested based on the new criteria.
Ref : 210
Title : Wave equation using finite element analysis 1D
Author(s) :
Name : Ahmed Samir Ewida Address : Zewail City of Science and Technology
Name : Ahmed Alghanam Address : Zewail City of Science and Technology
Name : Waleed Hamdy Elshemy Address : Zewail City of Science and Technology
Accepted : 1/14/2016 12:16:00 PM
Abstract :
Blogging the approximate solution back to the equation and multiplying by weighting function and integrate over the whole domain, we find weighting function.
Ref : 209
Title : Theoretical study on the influence of wavelength in laser-induced breakdown and plasma formation of CO2 gas.
Author(s) :
Name : M.A A.Elsayed Address : Department of Physics, Faculty of Science, Menoufia University, Egypt.
Name : Y. S. Rammah Address : Department of Physics, Faculty of Science, Menoufia University, Egypt.
Name : M.M. El-Kholy Address : Department of Physics, Faculty of Science, Menoufia University, Egypt.
Name : Y.EE-D. Gamal Address : National Institute of Laser Enhanced Science, Cairo University, Egypt.
Accepted : 1/14/2016 3:52:00 AM
Abstract :
During the last few decades the phenomenon of gas breakdown and plasma generation has attracted the interest of many physicists due to its important applications in different scientific and science life fields. Practically this phenomenon depends mainly on laser characteristics and nature of gas. Previous studies that carried out to investigate this phenomenon revealed with a great success many of the physical concepts when laser sources of wavelengths in the infra-red and visible regions of the electromagnetic spectrum are used. While for shorter wavelengths the investigation of this phenomenon still represents an open question. In this work a theoretical investigation of the breakdown of CO2 gas at atmospheric pressure induced by laser sources operating at different characteristics is presented. This gasis deliberately chosen since it represents one of the highest pollutants in the atmosphere. The study based on the application of a modified electron cascade model which solves numerically the time dependent Boltzmann equation for the electron energy distribution function (EEDF) simultaneously with a set of rate equations that describe the rate of change of the formed excited states population. The model takes into account all the possible physical processes which might take place in the interaction volume. Calculations are performed corresponding to published experimental measurements on the breakdown of CO2 by wide range of wavelengths to obtain the following outcomes: (i) a relation between the threshold irradiance and laser wavelength, (ii) comparison between the calculated and measured thresholds to validate the model, and (iii) the EEDF and its parameters to determine the contribution of each physical process to the breakdown phenomenon and its effect on determining the threshold intensity for the corresponding wavelength.
Ref : 208
Title : Peristaltic Transport with Cilia Influence of Magneto-Fluid Through a Porous Medium: Numerical Study
Author(s) :
Name : Kh. S. Mekheimer Address : Mathematical Department, Faculty of Science (Men), Al-Azhar University, Nasr City 11884, Cairo, Egypt
Name : R.E. Abo-Elkhair Address : Mathematical Department, Faculty of Science (Men), Al-Azhar University, Nasr City 11884, Cairo, Egypt
Name : A.M.A. Moawad Address : Mathematical Department, Faculty of Science (Men), Al-Azhar University, Nasr City 11884, Cairo, Egypt
Accepted : 1/14/2016 3:53:00 AM
Abstract :
The aim of this problem is to study the peristaltic transport with cilia influence of magneto, Newtonian, homogeneous and incompressible viscous fluid through a porous medium in a two-dimensional symmetric channel by using Adomian Decomposition Method to solve it. The expressions for stream function, velocity and vorticity are obtained without any approximation for the governing equations and also for the choice of the problem parameters values, but we used the Adomian Decomposition Method as approximated one. The effects for arbitrary values of the problem parameters on flow characteristics are studied in detail.
Ref : 207
Title : Application Decision Making-Based Scheme for Method Offloading in Mobile Cloud Computing Environments
Author(s) :
Name : Ahmed A.A. Gad-ElRab Address : Department of Mathematics Faculty of Science Al-Azhar University, Cairo, Egypt
Name : T.A.A. Alzohairy Address : Department of Mathematics Faculty of Science Al-Azhar University, Cairo, Egypt
Accepted : 1/14/2016 3:53:00 AM
Abstract :
Ref : 205
Title : The estimations under power normalization for the tail index, with comparison
Author(s) :
Name : E. M. Nigm Address : Zagazig University-Faculty of Science-Egypt
Accepted : 1/13/2016 8:09:00 AM
Abstract :
The objective of this talk is to suggest two classes of moment and moment ratio estimators under power normalization for the tail index. Moreover, for quantitative comparison of the suggested estimators and other estimators, we use a mean square error criterion. The problem of weighting between the linear and power models to describe the given extreme data is challenging. For this purpose, we suggest the coefficient variation criterion. A simulation study is conducted, to assess and compare the accuracy of the suggested estimators and other estimators, as well as the suggested statistical criterions. The suggested estimators and other estimators, as well as the suggested criterions are used to analyze a real data sets. All computations in this work
are performed by R-package.
AMS 2010 Subject Classification: :} 62G32, 62G30.
Key Words: :} Power normalization; generalized Pareto distributions; Hill estimators; moment estimator; moment ratio estimator
Remark: This talk is based on the recently submitted paper: Barakat, H. M. & Nigm, E. M. & Khaled, O. M. & Alaswed , A. M. (2015). The estimations under power normalization for the tail index, with comparison.
Ref : 204
Title : Asymptotic behavior of the joint record values, with applications
Author(s) :
Accepted : 1/13/2016 7:51:00 AM
Abstract :
Abstract: In this talk, the joint upper record values and the joint lower record values are discussed. The class of limit distribution functions of the joint upper record values, as well as the joint lower record values, is fully characterized. Sufficient conditions for the weak convergence are obtained. As an application of this result, the sufficient conditions for the weak convergence of the record quasi-range, record quasi-midrange, record extremal quasi-quotient and record extremal quasi-product are obtained. Moreover, the classes of the non-degenerate limit distribution functions of these statistics are derived.
AMS 2010 Subject Classification: Primary 60F05, 62E20; Secondary 62E15.
Key Words: Weak convergence; record values; joint record values, record functions.
Remark: This talk is based on the recently submitted paper: Barakat, H. M. and Abd Elgawad, M. A. (2015). Asymptotic behavior of the joint record values, with applications
Ref : 203
Title : Reviewing Computer Aided Systems for Breast Cancer Diagnosis in Ultrasound images
Author(s) :
Name : Mohamed Meselhy Eltoukhy Address : Computer Science Department, Faculty of Computers and Informatics, Suez Canal University, Ismailia, Egypt
Name : Abdelalim K. Farag Address : Computer Science Department, Faculty of Computers and Information, Menoufia University, Shebin El-kom, Egypt
Name : Noura M. A. Abdelwahed Address : Faculty of Computers and Informatics, Suez Canal University, Ismailia, Egypt
Accepted : 1/13/2016 7:51:00 AM
Abstract :
Abstract— Breast cancer is a common disease among the women worldwide. Computer aided breast cancer diagnosis has been actively researched for last few decades. The main aim of the paper is to identify the method used in CAD for breast cancer detection in ultrasound images. This paper summarizes the methods used in segmentation, feature extraction and classification of breast cancer in ultrasound images. The advantages and disadvantages of different methods are illustrated. This review is helpful for appropriate use of existing methods as well as designing of new methods to improve the accuracy of CAD systems. In addition, some new directions are suggested.
Keywords— Computer aided diagnosis; Ultrasound images; Breast cancer; Image segmentation methods; Image classification techniques;
Ref : 202
Title : Another Modification of Generalized Closed Sets Via Nano Topology
Author(s) :
Name : S. M. Darwesh Address : Department of Mathematics, Faculty of Science, Al-Azhar University, Nasr City (11884), Cairo, Egypt.
Name : A. A. Nasef Address : Department of Physics and Engineering Mathematics, Faculty of Engineering, Kafr El-Sheikh University, Kafr El-Sheikh, Egypt.
Name : A. I. Aggour Address : Department of Mathematics, Faculty of Science, Al-Azhar University, Nasr City (11884), Cairo, Egypt.
Name : S. M. Darwesh Address : S. M. Darwesh
Accepted : 1/13/2016 7:51:00 AM
Abstract :
This paper continues the study of some classes of generalized closed sets in a nano topological spaces. Our main objective is to establish results about the relationships between the various of nano generalized closed sets.
Ref : 201
Title : Improved Performance Of Text –Independent Speaker Identification Using MFCC, LPC and Gender Detection
Author(s) :
Name : Nagwa M.AboElenein Address : Eygpt-gharbia- kafer elzayat
Name : Khalid M.Amin Address : Eygpt-cario
Name : Mina I. Samaan Address : Eygpt-cario
Accepted : 1/13/2016 7:51:00 AM
Abstract :
Speaker identification identifies the speaker among a set of users by matching against a set of voiceprints. In this paper text independent speaker identification model is developed by combining linear predictive coding (LPC) and Mel Frequency Cepstral Coefficients (MFCC). The objective of this method is to extract additional features to help in the recognition process, and the numbers of speakers are reduced in test by gender detection algorithm. The pertinence of Gaussian Mixture Mode (GMM) is studied as classifier. The proposed method is implemented for corpus database for 18 male speakers and 18 female speakers. The experiment result shows, that the speaker identification rate for LPC+MFCC is 91.6 % and proposed method is 97.2% .
Ref : 200
Title : Existence of almost automorphic solutions for some evolution equations
Author(s) :
Name : Mohsen Miraoui Address : Institut Préparatoire aux Etudes dIngénieur de Kairouan, Kairouan, Tunisie.
Accepted : 1/13/2016 1:44:00 AM
Abstract :
In this work, we study some results regarding the completness and the invariance of the space consisting in (mu;nu)-pseudo almost automorphic functions and we show the existence and uniqueness of (mu;nu)-pseudo almost automorphic solutions to some nonautonomous differential equations
Ref : 199
Title : Electro-Magneto hydro oscillatory flow of dielectric fluid through a porous medium with heat transfer
Author(s) :
Name : Kh. S. Mekheimer Address : Mathematics Department, Faculty of Science, Al-Azhar University, Nasr City, Egypt.
Name : R.E. Abo-Elkhair Address : Mathematics Department, Faculty of Science, Al-Azhar University, Nasr City, Egypt.
Name : A.Z.Zaher Address : Mathematics and Physics Engineering Department, Faculty of Engineering - Shubra- Benha University,Egypt.
Accepted : 1/13/2016 1:44:00 AM
Abstract :
In this paper we study the effect of electro-magnetic field and heat transfer on the oscillatory flow(peristaltic flow) of an incompressible viscous fluid through a porous medium in a symmetric flexible channel.Numerical solution of stream function ,axial velocity,electric field,and temperature obtained by regular perturbation method.The perturbation solution of the system is derived by considering a small wave number.The effect of pertinent parameters is demonstrated and discussed.
Ref : 198
Title : L-Fuzzy nbd topological groups and L-fuzzy uniformities
Author(s) :
Name : Enas Hassan Samy Elkordy Address : Beni-Suif
Accepted : 1/13/2016 1:44:00 AM
Abstract :
Our main purpose of this paper is to highlight the concept of the topological group and introduce a stratified L-fuzzy neighborhood topological group and some related theorems. We managed to introduce two kinds of L-fuzzy uniformities of L-fuzzy neighborhood topological groups. The first one is of the stratification property and the second L-fuzzy uniformity is of the complete MV-algebra valued L-fuzzy neighborhood topological group. Some interesting results are obtained.
Ref : 196
Title : Tracking of multiple interacting objects based on Gabor-wavelet transform
Author(s) :
Name : R. M. Farouk Address : Mathematics Department, Faculty of Science Zagazig University, Egypt.
Name : Atef A. Galal Address : Department of Mathematics, Faculty of Science, Assuit University, Assuit, Egypt
Name : M. H. Marghny Address : Faculty of Information and Computers, Assiut University, Egypt
Accepted : 1/13/2016 1:45:00 AM
Abstract :
The problem of tracking multiple interacting objects is considering one of the challenges in computer vision. In this paper we have proposed a new technique based on Gabor wavelets blobs tracking and particle filter technique. The proposed algorithm show a promise results of tracking multiple interacting objects in the presence of partial occlusion. The problem of partial occlusion in computer vision field is considering NP-problem. Gabor wavelet transform is interested in analyzing signal at different scales and different orientations. In the tracking process we have determined certain points on each object and then extracted a Gabor blobs around this points. For all objet tracking we have tracked, we have tracked the blobs on each moving object. We have tested our algorithm on a digital video with simple and complex background. In each video we have used our algorithm is able to tracking all interacting objects.
Ref : 195
Title : Modification to the Variation of Tutte Polynomial of n- Cycle Graphs
Author(s) :
Name : Elrokh, A. Address : Mathematics Department, Faculty of Science, Sheben El-Kom University, Menoufia, Egypt.
Accepted : 1/13/2016 1:45:00 AM
Abstract :
Recently, the authors have investigated and discussed the variation of Tutte polynomial of n - cycle graphs under the action of the time [4]. In this paper ,we discuss the same variation but in higher dimensions to get partial derivatives of these n-cycle graphs with respect to x (edges) and y (loops) using the time consideration.
Ref : 194
Title : Power Lomax Distribution: Model for Bladder Cancer Data
Author(s) :
Accepted : 1/13/2016 1:45:00 AM
Abstract :
A new three-parameter continuous distribution, namely, Power Lomax distribution is proposed and studied for remission times of bladder cancer data. It offers a more flexible model for lifetime data. It can accommodate both inverted bathtub and decreasing hazard rate. Several statistical and reliability properties are derived, including the behavior of the density and hazard rate functions, the moments, the quantile function, and the limiting distributions of order statistics and extreme values. Point estimation via method of moments and maximum likelihood besides the interval estimation are studied. The simulation schemes are carried out to examine the bias and mean square error of the maximum likelihood estimators of the parameters. Finally, a real data application is illustrated the performance and applicability of the new distribution for bladder cancer data and compared with the fit attained known extensions of Lomax distribution.
Ref : 193
Title : On Some Generalizations of Certain Retarded Nonlinear Integral Inequalities and Their Applications in Delay Di erential Equations
Author(s) :
Name : A. A. El-Deeb Address : Department of Mathematics, Faculty of Science, Al-Azhar University, Nasr City (11884), Cairo, Egypt
Name : Reda Gamal Ahmed Address : Department of Mathematics, Faculty of Science, Al-Azhar University, Nasr City (11884), Cairo, Egypt
Accepted : 1/11/2016 2:52:00 PM
Abstract :
The main aim of this article is to investigate some new explicit bounds on solutions to a class of new nonlinear retarded integral inequalities of Gronwall type. By some new techniques, we generalize the results presented by Pachpatte in [10] to nonlinear retarded integral inequalities, where the case of non-retarded $t$ is changed into retarded case $\alpha(t)$. We also present an application to illustrate the usefulness of some of our results in estimation of the solution of delay nonlinear differential equations with given initial conditions.
Ref : 192
Title : A two dimensional approach for finding solutions of nonlinear fractional programming problems
Author(s) :
Name : H.A.Eldidamony Address : Department of Basic Science, Higher Technological Institute, 10th of Ramadan city, Egypt.
Name : E.A.Youness Address : Department of Mathematics, Faculty of Science, Tanta University, Tanta, Egypt.
Name : M.A.Maaty Address : Department of Basic Science, Higher Technological Institute, 10th of Ramadan city, Egypt
Accepted : 1/10/2016 5:07:00 PM
Abstract :
The problem of finding the minimum value of the objective function of the fractional programming problems has attracted considerable research and interest in many fields such as production planning, financial and corporate planning, health care and hospital planning, etc. In this paper, a two-dimensional approach for finding solutions of nonlinear fractional optimization problems is introduced. The proposed algorithm shows how to obtain a new point and a new direction in the feasible region, improving the process of solution depending on choosing three initial points from the feasible region without any conditions. The proposed algorithm is based mainly upon parametric method, which is very easy to understand and apply. The convergence of the proposed algorithm is discussed and illustrative examples are presented.
Ref : 191
Title : Toward an Efficient Simulation of Colored Hybrid Petri Nets on the GPU
Author(s) :
Name : Ismail Abd Elsattar Mohammed Ali Elansary Address : Mathematics and Computer Science Department, Faculty of Science, Port Said University
Name : Mostafa Mahmoud Ali Herajy Address : Mathematics and Computer Science Department, Faculty of Science, Port Said University
Name : Alaa Abd El Fattah Soliman Hefnawy Address : Computer and Systems Department, Electronics Research Institute
Name : Nasser Hassan Sewilam Address : Mathematics and Computer Science Department, Faculty of Science, Cairo University
Accepted : 1/10/2016 5:07:00 PM
Abstract :
The scales of biological models have been rabidly increased. Colored Petri nets are a promising tool to model such biological system, which extend the power of Petri nets by assigning colours to places. Moreover, colored Petri nets permit scaling up the size of a model consisting of many similar component by adding new colours. However, the serial implementation of colored Petri nets is prohibitively slow. Particulary, when biger and more complex models are considered. Therefore, speeding up the simulation of colored models is of a paramount importance. One direction to achieve this goal is to resort to parallel processing.
In this paper, we report our work of progress of using Graphics Processing Unit (GPU) to increase the efficiency of simulating colored models. We focus on a speci c class of colored Petri nets called colored hybrid Petri nets (HPN^C), which integrate all the features of hybrid Petri nets and colored Petri nets into one class. Moreover, HPN^C are ideal for modeling and analyzing complex and multiscale biological systems.
Keywords: colored hybrid Petri nets, GPU, large scale biological systems, parallel simulation, CUDA
Ref : 188
Title : On Real-Time Recognition of Arabic License Plates Using GPU.
Author(s) :
Name : Walid Hamdy Kamel Tolba Address : Mathematics and Computer Science Department, Faculty of Science, Port Said University
Name : Mostafa Mahmoud Ali Herajy Address : Mathematics and Computer Science Department, Faculty of Science, Port Said University
Name : Hatem Mohamed Abd El Kader Moharram Address : Mathematics and Computer Science Department, Faculty of Science, Cairo University.
Name : Alaa Abd El Fattah Soliman Hefnawy Address : Head of Computer & Systems Department, Electronic Research Institute.
Accepted : 1/10/2016 8:20:00 AM
Abstract :
Automatic License plate recognition plays a key role in accelerating the process of identifying vehicle data. It has many applications in intelligent traffic systems such as parking fee, highway toll fee, traffic data collection
and traffic monitoring systems. However, there is a significant increase in the number of cars worldwide. Thus the process of license plate recognition consumes a substantial amount of time, particularly with the increase number of cars. Implementing LPR on a single core processor with a tremendous number of cars will take more time. However, LPR systems usually requires real-time processing to take advantage of applications to LPR. Therefore we use the graphics processing unit to accelerate license plate recognition performance where a large number of cores collaborate in achieving a real time performance of LPR. Furthermore, we apply LPR on Arabic written plates which result in new challenges to existing recognition systems.
In this paper we report our work in progress of exploring the power of parallel processing to increase the efficiency of license plate recognition (LPR). More specifically, we utilize graphical processing unit (GPU) to increase performance of LPR. We aim to get a real time performance using GPU. Moreover, we use CUDA to implement the proposed framework.
Keywords: License plate recognition (LPR), graphics processing unit(GPU), CUDA, Arabic plate recognition, parallel recognition, intelligent traffic systems.
Ref : 186
Title : A two dimensional approach for finding solutions of nonlinear fractional programming problems
Author(s) :
Name : H.A.Eldidamony Address : Department of Basic Science, Higher Technological Institute, 10th of Ramadan city, Egypt
Name : E.A.Youness Address : Department of Mathematics, Faculty of Science, Tanta University, Tanta, Egypt.
Accepted : 1/10/2016 8:20:00 AM
Abstract :
The problem of finding the minimum value of the objective function of the fractional programming problems has attracted considerable research and interest in many fields such as production planning, financial and corporate planning, health care and hospital planning, etc. In this paper, a two-dimensional approach for finding solutions of nonlinear fractional optimization problems is introduced. The proposed algorithm shows how to obtain a new point and a new direction in the feasible region, improving the process of solution depending on choosing three initial points from the feasible region without any conditions. The proposed algorithm is based mainly upon parametric method, which is very easy to understand and apply. The convergence of the proposed algorithm is discussed and illustrative examples are presented.
Ref : 185
Title : An Efficient Likelihood-Based Modulation Classification Algorithm for MIMO Systems
Author(s) :
Name : Mohammad Rida Bahloul Address : Centre for Intelligent Signal and Imaging Research (CISIR), Department of Electrical and Electronics Engineering, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak, Malaysia
Name : Abdel-Haleem Abdel-Aty Address : Physics and Computers Department, Faculty of Science, Al-Azhar University, Assiut, Egypt
Accepted : 1/10/2016 8:20:00 AM
Abstract :
Blind algorithms for multiple-input multiple-output (MIMO) signals interception have recently received considerable attention due to its important applications in modern civil and military communication fields. One key step in the interception process is to blindly recognize the modulation type of the MIMO signals. This can be performed by employing Modulation Classification (MC) algorithm, which can be feature-based or likelihood-based. In this paper, we focus on likelihood-based MC algorithms for MIMO systems rather than feature-based ones since they can provide optimal solutions, when the unknown parameters or their reliable estimates are available at the receiver side. To overcome the problems associated with the existing likelihood-based algorithms, a new algorithm is developed in this paper. The formulation of the MC problem is simplified in this algorithm by treating the individual estimated transmit signals as independent processes, where a weighted sum rule is introduced to combine the likelihood functions of the estimated transmit signals under each hypothesis. The proposed algorithm shows good performance under different operating conditions, over an acceptable range of SNR, without any prior information about the channel state. It also shows a performance close to the upper bound while having a significantly lower computational complexity.
Ref : 184
Title : Soft Metric Spaces
Author(s) :
Name : Radwa Mohamed Ahmed Address : Mathematics Department, Faculty of Science, Suez Canal University, Ismailia, Egypt
Accepted : 1/10/2016 4:00:00 AM
Abstract :
After the famous article of Moldotsove in 1999 which initiate the theory of soft sets as a mathematical theory to dealing with the uncertainty, many research works in the soft mathematics and its applications in various field are appeared.
In the present paper, soft metric function is introduced using the soft elements of the soft space. By this definition each soft metric in view of Das and Samanta is also a soft metric in our concept but the converse is not true. Also, some soft topological properties are given in detail.
We hope that the findings in this paper will help researcher enhance and promote the further study on fuzzy soft topology to carry out a general framework for their applications in practical life.
Ref : 183
Title : A HYBRID GENETIC ALGORITHM FOR JOB_SHOP SCHEDULING PROBLEMS
Author(s) :
Name : Sarah Mohammed Nasr Address : Department of Basic Engineering Science, Faculty of Engineering, Shebin El-Kom, Menoufia University, Egypt.
Name : M.A. El-Shorbagy Address : Department of Basic Engineering Science, Faculty of Engineering, Shebin El-Kom, Menoufia University, Egypt.
Name : I.M. El_Desoky Address : Department of Basic Engineering Science, Faculty of Engineering, Shebin El-Kom, Menoufia University, Egypt.
Name : A.A. Mousa Address : Department of Basic Engineering Science, Faculty of Engineering, Shebin El-Kom, Menoufia University, Egypt.
Name : Z. M. Hendawy Address : Department of Basic Engineering Science, Faculty of Engineering, Shebin El-Kom, Menoufia University, Egypt.
Accepted : 1/10/2016 12:28:00 AM
Abstract :
Abstract — Job Shop Scheduling Problem(JSSP) is an optimization problem in which ideal jobs are assigned to resources at particular times. In recent years many attempts have been made at the solution of this problem using a various range of tools and techniques. This paper presents a hybrid genetic algorithm(GA) for JSSP. The hybrid algorithm is a combination between genetic algorithm and local search. Firstly, A generation alternation model using GA is designed. A new initialization method is proposed. Advanced crossover and mutation operators are used. Then local search based on the neighborhood structure is applied in the GA result. The approach is tested on a set of standard instances taken from the literature. The computation results have validated the effectiveness of the proposed algorithm.
Keywords: Genetic algorithm, Job shop scheduling problem, Local search
Ref : 182
Title : Centralized Topological Map Extraction Technique for Low Density Wireless Sensor Network
Author(s) :
Name : Walaa Ali Address : Menofia university
Name : Osama Shebl Address : Menofiea University
Name : Hatem Elsayed Address : Menofia university
Accepted : 1/10/2016 12:28:00 AM
Abstract :
Wireless sensor networks consist of varying number of randomly deployed tiny sensors. One of its main applications is monitoring environmental phenomena’s in remote and rugged places. In such applications, sensors are distributed with helicopter passing over the area of study. This way of distribution cause different density sub-regions and unknown topology structure. Information is needed to be shared between sensors to enable them to detect and extract topological features about their random distribution. In this paper, we propose a technique which depends on performing a simple spatial analysis on the nodes’ position. This technique enables the base station to construct a topological map using collected spatial information from sensors. To the best of our knowledge, this is the first study for this problem which concern low density networks.
Ref : 181
Title : Prediction of Missing Values of any Numerical Information System Tables by Using Rough Sets
Author(s) :
Name : Elsayed Sallam Address : Computer and Automatic Control Department, Faculty of Engineering, Tanta University, Tanta, Egypt.
Name : T. Medhat Address : Computer and Automatic Control Department, Faculty of Engineering, Kafrelsheikh University, 33516, Kafrelsheikh, Egypt.
Name : A.Ghanem Address : Kafrelsheikh University portal manger, Kafrelsheikh University, 33516, Kafrelsheikh, Egypt
Accepted : 1/10/2016 12:29:00 AM
Abstract :
This paper proposes a model for predicting missing values of any attributes for numerical information system tables. The model depends on three methods: KNN (K nearest neighbors) Imputation, rough set and most common value. This model presents two methods and one improvement to them. This model will be discussed in detail with an example of a case study. Web application was developed to apply this proposed model by c#, asp.net and SQL server.
Ref : 180
Title : فاعلية التعلم المقلوب في تعل م وتعليم الرياضيات
Author(s) :
Name : مريم زيد زيدان العمري Address : إدارة التعليم بمحافظة ينبع
Accepted : 1/9/2016 11:17:00 AM
Abstract :
It was observed that self-learning through the computer contributes to instill in students a variety of educational positions, through Giving skills and experience useful, as was noted academic achievement influenced to some students because of the large number of their absence, and the lack of communication mothers of the students; which necessitated the search for a
strategy to involve parents in the stand on level grades for the students; the goal of the use of education technology and techniques. And help students to mastery of new data. It also lies the importance of the experience to stand on the use of information and communication of modern technology, learning inverted and is defined as: "an educational model aims to use modern technologies and the Internet, in a manner allows the teacher to prepare the lesson through the media; to the attention of their students at home or anywhere else, using the computer, or smartphones, or tablets, as and locate Education, was selected video links. and measured the effectiveness of the inverted learning, through the design of a questionnaire to explore the views of parents, and highlighted the results of the experiment the evolution of the role of Almlqna parameter, to become oriented, and stimulating, and a guide, and help. The base configuration of the feedback for students in fourth-grade math. It is the key recommendations to provide dedicated time, reserve quotas;
to train students and develop their performance. work training workshops; to exchange experiences among students.
Ref : 179
Title : Soft Metric Spaces
Author(s) :
Name : Osama Abd El-Hamid Tantawy Address : Department of Mathematics, Faculty of Science, Zagazig University, Zagazig, Egypt
Accepted : 1/9/2016 11:08:00 AM
Abstract :
After the famous article of Moldotsove in 1999 which initiate the theory of soft sets as a mathematical theory to dealing with the uncertainty, many research works in the soft mathematics and its applications in various field are appeared. In the present paper, soft metric function is introduced using the soft elements of the soft space. By this defi nition each soft metric in view of Das and Samanta is also a soft metric in our concept but the converse is not true. Also, some soft topological properties are given in detail. We hope that the fi ndings in this paper will help researcher enhance and promote the further study on fuzzy soft topology to carry out a general framework for their applications in practical life.
Ref : 178
Title : Managing uncertainty in an automotive industry supply chain model
Author(s) :
Name : Duaa Gomaa Address : Shibin El-Kom, Menoufia, Egypt
Name : Osama Abdel-Raouf Address : Shibin El-Kom, Menoufia, Egypt
Accepted : 1/9/2016 11:08:00 AM
Abstract :
Supply chain (SC) is one of these real-life problems with uncertain decision making variables. SC linear programming model tries to minimize the total transportation costs between elements of Supply chain management (SCM). SC works in an uncertain environment like customer demand, supply deliveries and market supply. The fuzzy sets, rough sets and rough-fuzzy sets are adequate for solving SC problem. This paper aims to use these sets in respect of their suitability for representing uncertain information. Finally, comparison between fuzzy set and rough set optimization results under uncertainty is presented. Rough set are used to give a better optimization basing on better accurate mathematical models. This set proved to be a convenient for decision maker for giving a wide optimized performance range.
Ref : 177
Title : On the existence of new solutions for the rotational motion of a rigid body under the action of a Newtonian force field
Author(s) :
Name : Tarek Saleh Amer Address : Mathematics Department, Faculty of Science, Tanta University, Tanta 31527, Egypt.
Name : Ibrahim Mohamed Abady Address : Mathematics Department, Faculty of Science, Tanta University, Tanta 31527, Egypt.
Accepted : 1/9/2016 8:37:00 AM
Abstract :
In this work, new solutions of the Euler’s dynamic equations for the rotational motion of a rigid body about a fixed point under the action of a Newtonian force field are studied. Some restrictions on the center of mass of the rigid body and on the values of the principle moments of inertia are assumed according to the investigated cases. The obtained solutions are represented graphically to describe the motion at any time and are considered as a modification of both Eulers and Lagranges cases. Moreover, the components of the angular velocity vector for these solutions are differing from the most famous cases. The obtained results can be exploited in industrial applications of the rigid body dynamics like robotics and computer games.
Ref : 176
Title : Prime Numbers and Application in Security Systems
Author(s) :
Name : Mohammed Ashraf Abd El-Kareem Address : Egypt- Giza - El-Sheikh Zayed- 13th district
Name : Osama Habshy Elsayed Address : 303/13 Suez canal st., Mohatram Pasha, Moharam Baik, Alexandria
Name : Maryam Sobhy Hebeishy Address : Cairo- Hadayek El Koba - Al Sakia st., 1-Ibrahim El Shimy
Accepted : 1/8/2016 1:17:00 PM
Abstract :
-Some Properties of prime numbers: Being infinite(proved), decreasing in density as the number range increases,and-seemingly contradicting- Mills constants, and Mersenne primes
-Fermats primality test (Fermats little theorem)
- RSA Security System (the security system used on almost all online encryption systems) and its use of prime numbers,Fermats little theorem, and Eulers Phi function.
Ref : 175
Title : The growth of vapour bubble between two-phase flow for non viscous and viscous fluids
Author(s) :
Name : M. H. Omran Address : Math. Department, Al-Arish Faculty of Science , Suez Canal University, Al-Arish, Egypt
Accepted : 1/8/2016 1:18:00 PM
Abstract :
In this paper , we studied the growth of vapour bubbles between two-phase flow. The growth problem is discussed for viscous and non viscous fluids. The mathematical model is performed by mass, momentum and heat equations and solved analytically by using a new assumption to derive the growth of a vapour bubble between two-phase viscous and non viscous fluid flow in terms of time and some another physical parameters. The growth of vapour bubble in a viscous fluids flow performs lower values than that in case of non viscous fluid flow. Moreover, the growth of vapour bubble between two-phase flow for viscous and non viscous fluid flow is affected by superheated, thermal diffusivity and initial growth. Results are compared with Mohammadein and Plesset models in case of bubble growth,
.
Ref : 174
Title : Soft Metric Spaces
Author(s) :
Name : Osama Abd El-Hamid Tantawy Address : Department of Mathematics, Faculty of Science, Zagazig University, Zagazig, Egypt
Accepted : 1/8/2016 1:18:00 PM
Abstract :
After the famous article of Moldotsove in 1999 which initiate the theory of soft sets as a mathematical theory to dealing with the uncertainty, many research works in the soft mathematics and its applications in various fi eld are appeared.
In the present paper, soft metric function is introduced using the soft elements of the soft space.
By this defi nition each soft metric in view of Das and Samanta is also a soft metric in our concept but the converse is not true. Also, some soft topological properties are given in detail.
We hope that the findings in this paper will help researcher enhance and promote the further study on fuzzy soft topology to carry out a general framework for their applications in practical life.
Ref : 172
Title : Summation of all natural numbers gives a value of -1/12
Author(s) :
Accepted : 1/8/2016 8:18:00 AM
Abstract :
Its known that the natural numbers series (1+2+3+4..) is a divergent series, however, many summation methods are used to give a numerical value for the series which is -1/12. Its really exotic that all methods yield the same value for a divergent series. Im going to show how this works using summation methods for series and Riemann-zeta function, and the applications based on it.
Ref : 171
Title : Solving Multi-objective Unit commitment Problem using a Genetic Algorithm based clustering technique
Author(s) :
Name : Mai A. Farag Address : Department of Basic Engineering Science, Faculty of Engineering, Menoufiya University, Egypt.
Name : M.A. El-Shorbagy Address : Department of Basic Engineering Science, Faculty of Engineering, Menoufiya University, Egypt.
Name : I.M. El_Desoky Address : Department of Basic Engineering Science, Faculty of Engineering, Menoufiya University, Egypt.&3Department of Mathematics, Faculty of Sciences, Taif University, Saudi Arabia
Name : A.A. Mousa Address : Department of Basic Engineering Science, Faculty of Engineering, Menoufiya University, Egypt,
Name : A.A. El-Sawy Address : 1Department of Basic Engineering Science, Faculty of Engineering, Menoufiya University, Egypt. Department of Mathematics, Faculty of Science, Qassim University, Saudi Arabia
Accepted : 1/6/2016 12:43:00 PM
Abstract :
This paper presents an intelligent computing based approach for solving multi-objective unit commitment problem (MOUCP) using binary-real-coded genetic algorithm (GA) based on K-means clustering technique to find the solution of the optimal schedule of the generation units. A binary-real-coded GA is used here in order to tackle both the unit scheduling and load dispatch problems. The binary part of the GA deals with the scheduling of units and the real part determines the amounts of power to be generated by committed units. K-means clustering algorithm is used to divide population into a specific number of subpopulation. In this way, different GA operators can apply to sub-populations instead of one GA operator applied to all population. The proposed algorithm has been tested on standard systems of MOUCPs. The results have been demonstrated the superiority of the proposed approach to solve MOUCPs. Furthermore, this paper presents a fuzzy model for the MOUCP. The model takes the uncertainties in fuel cost coefficients in a fuzzy frame. With this model, the proposed algorithm gives a set of non-dominated solutions using different α cut level.
Ref : 170
Title : DNA-based watermarking technique for protecting the copyrights
Author(s) :
Name : Basmaa Ahmed AbdElHafez Address : Faculty of Science, South Valley University,Egypt
Name : S. Z.Rida Address : Faculty of Science, South Valley University
Name : Marghny H. Mohamed Address : Faculty of Computers and Information, Assiut University
Accepted : 1/5/2016 3:52:00 PM
Abstract :
The Development of the Internet along with the increasing availability of multimedia applications has Generated a number of copyright issues. One of the topic that Development has fueled is digital watermarking.Digital watermarking is the act of hiding a message related to a digital signal (i.e. an image, song, video, DNA) within the signal itself.DNA watermarking is a technique for copyright protection and ownership authentication of DNA sequences and ensures the security of private genetic information. In This paper, we proposes a coding DNA watermarking technique based on the Discrete WaveletTransform (DWT) domain that relies on frequency domain for DNA sequences. The technique divides a coding DNA sequence into number of subsequences and assign all codons in subsequences to a numerical code. Then, calculate DWT coefficients that are optimal for embedding watermark bits. Finally, we apply the data hiding equation and process IDWT with amino acid conservation.
Ref : 169
Title : Fast inversion of electromagnetic logging-while-drilling measurements acquired in multiple wells
Author(s) :
Name : Shaaban Ali Bakr Address : Basque Center for Applied Mathematics (BCAM), Bilbao, Spain, and Department of Mathematics, Assiut University, Assiut 71516, Egypt.
Name : David Pardo Address : Department of Applied Mathematics, Statistics, and Operational Research, University of the Basque Country (UPV/EHU), Leioa, Spain, Basque Center for Applied Mathematics (BCAM), and IKERBASQUE (Basque Foundation for Sciences), Bilbao, Spain.
Accepted : 1/5/2016 8:59:00 AM
Abstract :
This paper describes a method for the fast
inversion of borehole resistivity measurements acquired in multiple wells.
There are two key novel contributions on this work. First, we extend the set of formation models from previously existing two-dimensions (2D) ones to three-dimensional (3D) transversely isotropic (TI) formations that are approximated by a sequence of several stitched" one-dimensional (1D) sections. This provides added flexibility in order to approximate complex 3D formations. Second, the developed inversion method enables to simultaneously invert measurements acquired at different wells and/or with different logging instruments.
Numerical experiments performed over realistic 3D synthetic formations illustrate the flexibility and superb inversion results obtained with the library, which enables to interpret resistivity measurements acquired at various wells (e.g., an exploratory, an offset, and a geosteering well) and with any combination of co-axial and/or tri-axial commercial logging instruments with known antennae configurations.
Ref : 168
Title : The Weibull Exponential Distribution: Properties and Applications
Author(s) :
Name : Ahmed M. T. Abd El-Bar Address : Mathematics Department, Faculty of Science, Tanta University, Tanta, Egypt
Name : I. E. Ragaba Address : Mathematics Department, Faculty of Science, Tanta University, Tanta, Egypt
Accepted : 1/4/2016 9:56:00 AM
Abstract :
In this paper we introduce a three-parameter distribution called Weibull exponential (WE) distribution which
offers a more flexible model for lifetime data. We show that the hazard rate of the new distribution can be
increasing or decreasing. The hazard rate can also be bathtub shaped. A comprehensive mathematical treatment
of the WE distribution is provided. We give closed-form expressions for the density, hazard rate, moments,
quantile function, mean residual life function, mean deviations, Bonferroni and Lorenz curves. We also derive
the density of ith order statistic. Moreover, we discuss estimation by the maximum likelihood and obtain an
expression for the observed information matrix. Furthermore, simulation results on maximum likelihood
estimation are presented. A two real data applications illustrates the performance of the distribution.
Ref : 166
Title : Study of nonlinear vibration of an electrostatically actuated microbeam by using global residue harmonic balance method
Author(s) :
Name : G. M. Ismail Address : Department of Mathematics, Faculty of Science, Sohag University, Sohag, 82524, Egypt.
Accepted : 1/4/2016 1:53:00 AM
Abstract :
A suggested class of certain technique that called global residue harmonic balance method to obtain analytical approximate solutions for the large-amplitude vibration of electrostatically actuated microbeams is used in the present work. To illustrate the applicability and accuracy of the method, the approximate solution results are compared with the numerical solutions and existing results. The obtained results ensure that this method is an easy one to solve many sophisticated nonlinear problems.
Ref : 165
Title : Bayesian estimation using MCMC approach on progressive first - failure censoring from inverse Weibull distribution
Author(s) :
Name : Azhari Abd Alla Alhag Address : Mathematics department, Faculty of Science, Taif university, Saudi Arabia
Name : Hamda Saed Mohmel Alharthi Address : Mathematics department, Faculty of Science, Taif university, Saudi Arabia
Name : Hamda Saed Mohmel Alharthi Address : Mathematics department, Faculty of Science, Taif university, Saudi Arabia
Accepted : 1/3/2016 8:43:00 AM
Abstract :
In this paper, we derive the maximum likelihood and Bayes estimation of the parameters of the inverse Weibull distribution (IWD) based on progressive first failure censored scheme. The Bayes estimator does not exist in an explicit form, so Markov chain Monte Carlo (MCMC) method is used generate from the posterior distribution . The approximate confidence intervals as well as credible intervals for the parameters are presented. Numerical example will be used to illustrate our purposes. Results from simulation studies will be used to assessing the performance of different method.
Ref : 164
Title : Bayesian estimation using MCMC approach on progressive first - failure censoring from inverse Weibull distribution
Author(s) :
Name : Azhari Abd Alla Alhag Address : Mathematics department, Faculty of Science, Taif university, Saudi Arabia
Name : Hamda Saed Mohmel Alharthi Address : Mathematics department, Faculty of Science, Taif university, Saudi Arabia
Accepted : 1/3/2016 8:43:00 AM
Abstract :
In this paper, we derive the maximum likelihood and Bayes estimation of the parameters of the inverse Weibull distribution (IWD) based on progressive first failure censored scheme. The Bayes estimator does not exist in an explicit form, so Markov chain Monte Carlo (MCMC) method is used generate from the posterior distribution . The approximate confidence intervals as well as credible intervals for the parameters are presented. Numerical example will be used to illustrate our purposes. Results from simulation studies will be used to assessing the performance of different method.
Ref : 163
Title : Nonclassical properties and geometric phase of Raman photon pairs in the presence of atomic motion effect
Author(s) :
Name : Sadah. A. Alkhateeb Address : Mathematics department, Faculty of Science, King Abdulaziz university, Jeddah, Saudi Arabia
Name : S. Abdel-Khalek Address : Mathematics department, Faculty of Science, Taif university, Saudi Arabia
Name : Eman M. A. Hilal Address : Mathematics department, Faculty of Science, King Abdulaziz university, Saudi Arabia
Accepted : 1/3/2016 2:58:00 AM
Abstract :
In this paper, we will theoretically investigate the efficient of correlated-photon generation by irradiating a four-level driven in a double-Raman configuration with pomp and drive laser, which emits a pair of Stokes and anti-Stokes photon. We will present more practical situations for the generation of the pair of Stokes and anti-Stokes photons considering the case of time-dependent coupling with the effect of the atomic speed. On the other hand, we will investigate the geometric phase of the pair of photons in terms of the physical parameters. Finally, we will investigate some other important physical properties of the atom and pair of generated photons considering the purity and nonclassicaliry.
Ref : 162
Title : Lie point symmetries for a magneto couple stress fluid in a porous channel with expanding or contracting walls and slip boundary condition
Author(s) :
Name : Rabea El Shennawy Abo elkhair Address : Mathematics Department, Faculty of Science, Al-Azhar University, Nasr City, 11448, Cairo, Egypt.
Accepted : 1/3/2016 1:20:00 AM
Abstract :
In this paper, an incompressible couple stress fluid flow with magnetic field in a porous
channel with expanding or contracting walls and slip boundary condition is considered. Lie
group analysis and group invariant solutions are obtained, the governing equations are reduced to nonlinear ordinary differential equations. The resulting equations are solved analytically, also this equations are solved by using Adomian method. The graphs for the axial and the normal velocity components and the pressure distribution for different values of the physical and geometric parameters are plotted and discussed. Finally, the comparison between the analytic and adomain methods is discussed.
Ref : 161
Title : Quantum Entanglement
Author(s) :
Name : Omar Muhammed El-Sayed Address : Zewail City of Science and Technology, Egypt
Accepted : 1/3/2016 1:21:00 AM
Abstract :
Undoubtedly, Quantum Mechanics is the most shocking physical theory to humans classical logic. This is because of the bizarre phenomena scientists observe in the quantum scale. One of the most shocking of these phenomena is what is called "Quantum Entanglement", which is a correlation that takes place between two particles that requires communication faster than the speed of light; what was so-called by Albert Einstein: "Spooky Action at a Distance". In this paper, I am going to introduce the basic concepts of Quantum Mechanics, and then proceed to discuss quantum entanglement and the debate about it, starting from Einstein and Bohr. I will also be discussing the EPR Paradox and Bells Inequality. I shall mention at the end a very recent experiment about Quantum Entanglement that supports the phenomenon to a great extent.
Ref : 160
Title : Fractal Geometry explains the Universe
Author(s) :
Name : Weam Moghazy Address : Zewail City
Name : Aya El Zahy Address : Zewail City
Accepted : 1/2/2016 3:18:00 PM
Abstract :
A novel approach to cosmology is presented that mathematically models the Universe as an iterated function system (IFS) analogous to the famous Mandelbrot Set IFS (M): z=z2+c, where z and c are complex numbers. In theoretical physics, wavefunctions are functions of a complex space that are commonly used to model the dynamics of particles and waves. In the IFS framework presented herein, complex dynamical systems are generated via the iteration process, where the act of iteration corresponds to 1) a change in the state of the system and 2) a change to the wavefunction itself. In this manner, M can be considered a wavefunction generator. In this framework, all observables, including gravity and time, are thought to be generated by the iteration process. Feynman understood that there are many ways of looking at the Universe that are equivalent in nature but different psychologically. Understanding cosmology in terms of fractals and iterated function systems requires a paradigm shift in the way we approach cosmology. This is an evidence based dissertation and does not contradict the standard model; rather, it attempts to reconstruct it using the principles of the fractal paradigm as outlined in this essay. It is the contention of the author that in order to understand the true nature of light, the universe and everything, we must first understand the important role that fractal cosmology plays in the study of our complex dynamical universe.
Ref : 159
Title : Fixed point theorems in multiplicative dislocated quasi-metric spaces
Author(s) :
Name : A.M. Zidan Address : Department of Mathematics, Faculty of Science, Al-Azhar University, Assiut
Name : A.M. Zidan Address : Department of Mathematics, Faculty of Science, Al-Azhar University, Assiut
Name : M.A. Ahmed Address : Department of Mathematics, Faculty of Science, Assiut University,
Accepted : 1/2/2016 1:03:00 AM
Abstract :
In this work, we introduce a new concept of generalized multiplicative metric spaces and dislocated quasi-metric spaces called multiplicative Md-quasi metric space. The main result of our paper is prove fixed point theorem in a complete multiplicative Md-metric space. An illustrative example is given to support our results.
Ref : 158
Title : Method of singular mass matrix and singular perturbation problem
Author(s) :
Name : Berkane Ali Address : Baji Mokhtar University, Annaba, Algeria
Accepted : 1/1/2016 9:49:00 AM
Abstract :
Abstract: In this work we study the approximation of hyperbolic operators of the first order or parabolic degenerate time. This method using the singular mass technique proposed to obtain optimal estimates of errors for classes of Lagrange finite elements.
Ref : 157
Title : Determination of heights
Author(s) :
Accepted : 1/1/2016 8:35:00 AM
Abstract :
In this talk I am going to discuss four different ways to determine the height. We will discuss some applications and show how sensitive reaction can be obtained using our models.
Ref : 156
Title : Extended one-step methods for solving delay differential equations
Author(s) :
Name : OYETNUDE RAPHAEL ANUOLUWAPO Address : P.M.B. 704 Akure, Ondo State
Name : OLAOKE AYOBAMI AKANNI Address : P.M.B. 704 Akure, Ondo State
Name : LASISI MOSHOOD AYIKI Address : P.M.B. 704 Akure, Ondo State
Accepted : 1/1/2016 8:36:00 AM
Abstract :
We provide a reliable and stable computational technique, based on a class of extended one-step methods for solving delay differential equations with constant and variable delays. Numerical stability properties of the schemes are investigated. The schemes are suitable for stiff and non-stiff problems. Numerical results and simulations are presented to demonstrate the effectiveness of the methodology.
Ref : 154
Title : Exact soltuions of the (3+1)-Dimensional Yu-Toda-Sasa-Fukuyama equation by using the extended exp (-Ф(ξ)) expansion method
Author(s) :
Name : Emad H. M. Zahran Address : Department of mathematical and physical engineering, college of engineering Shubra, university of Benha, Egypt
Accepted : 1/1/2016 8:36:00 AM
Abstract :
In this research, we employ the extended exp(- Ф(ξ)) expansion method to obtain the exact and solitary wave solutions of the (3+1)-Dimensional Yu-Toda-Sasa-Fukuyama Equation. We obtain the wide range of exact and solitary wave solutions of distinct physical structure.
Ref : 153
Title : A New Lifetime Distribution for a Series-Parallel System: Properties, Applications and Estimations Under Progressive Type-II Censoring
Author(s) :
Name : Alaa Hashem Abdel-Hamid Address : Department of Mathematics and Computer Science, Faculty of Science, Beni-Suef University
Name : Atef. F. Hashem Address : Department of Mathematics and Computer Science, Faculty of Science, Beni-Suef University
Accepted : 12/31/2015 9:09:00 AM
Abstract :
A compound class of zero truncated Poisson and lifetime distributions is introduced. A specialization is paved to a new three-parameter distribution, called doubly Poisson-exponential distribution, which may represent the lifetime of units connected in a series-parallel system. The new distribution can be obtained by compounding two zero truncated Poisson distributions and an exponential distribution. Among its motivations is that the hazard rate function has decreasing, increasing and upside-down bathtub shapes. Several properties of the new distribution are discussed. Based on progressive type-II censoring, six estimation methods [maximum likelihood, moments, least squares, weighted least squares and Bayes (using linear-exponential and general entropy loss functions) estimations] are used to estimate the involved parameters and compare their performance through a simulation study. The Bayes estimates are obtained using Markov chain Monte Carlo algorithm. In addition, the confidence intervals, symmetric credible intervals and highest posterior density credible intervals of the parameters are obtained. Finally, an application to a real data set is used to compare the new distribution with other five distributions.
Ref : 151
Title : Reliable and stable computational technique
Author(s) :
Name : OYETNUDE RAPHAEL ANUOLUWAPO Address : P.M.B. 704 Akure, Ondo State
Name : OLAOKE AYOBAMI AKANNI Address : P.M.B. 704 Akure, Ondo State
Name : LASISI MOSHOOD AYIKI Address : P.M.B. 704 Akure, Ondo State
Accepted : 12/31/2015 9:10:00 AM
Abstract :
We provide a reliable and stable computational technique, based on a class of extended one-step methods for solving delay differential equations with constant and variable delays. Numerical stability properties of the schemes are investigated. The schemes are suitable for stiff and non-stiff problems. Numerical results and simulations are presented to demonstrate the effectiveness of the methodology.
Ref : 150
Title : DNA-based watermarking technique for protecting the copyrights
Author(s) :
Name : Basmaa Ahmed AbdElHafez Address : Faculty of Science, South Valley University, Egypt
Name : Saad Zagloul Rida Address : Faculty of Science, South Valley University
Accepted : 12/31/2015 3:13:00 AM
Abstract :
The Development of the Internet along with the increasing availability of multimedia applications has Generated a number of copyright issues. One of the topic that Development has fueled is digital watermarking.Digital watermarking is the act of hiding a message related to a digital signal (i.e. an image, song, video, DNA) within the signal itself. It is a concept closely related to steganography as both of them hide a message inside a digital signal.DNA watermarking is a technique for copyright protection and ownership authentication of DNA sequences and guarantees the security of private genetic information. In This paper, we proposes a coding DNA watermarking technique based on the Discrete WaveletTransform (DWT) domain that rely on frequency domain for DNA sequences. The technique divides a coding DNA sequence into number of subsequences and assign all codons in subsequences to a numerical code. Then, calculate DWT coefficients that are optimal for embedding watermark bits.Then, we apply the data hiding equation. After that processing IDWT with amino acid conservation.
Ref : 149
Title : Fixed point theorems in multiplicative dislocated quasi-metric spaces
Author(s) :
Name : A.M. Zidan Address : Department of Mathematics, Faculty of Science, Al-Azhar University, Assiut .
Accepted : 12/31/2015 3:13:00 AM
Abstract :
In this work, we introduce a new concept of generalized multiplicative metric spaces and dislocated quasi-metric spaces called multiplicative Md-quasi metric space. The main result of our paper is prove fixed point theorem in a complete multiplicative Md-metric space. An illustrative example is given to support our results.
Ref : 148
Title : Optimal design for step-stress partially accelerated life tests under progressive type-I interval censored data from generalized Pareto distribution
Author(s) :
Name : Rashad Mohamed EL-Sagheer Address : Mathematics Department, Faculty of Science, Al-Azhar University, Naser city 11884, Cairo, Egypt.
Accepted : 12/30/2015 2:29:00 PM
Abstract :
This article discusses k-stage step-stress partially accelerated life tests under type-I progressive interval censoring with equal inspection intervals of length. The maximum likelihood and parametric bootstrap methods are used to obtain the estimators of the model parameters. Approximate confidence intervals for the unknown parameters are constructed based on the asymptotic variances when the lifetime of a testing unit are assumed to be generalized Pareto distribution. The methods for obtaining the optimal are investigated using the variance-optimality and determinant-optimality criteria. Monte Carlo simulation studies are discussed to illustrate the proposed criteria.
Ref : 147
Title : Geometric phase and entanglement of three-level atom with and without rotating wave approximation
Author(s) :
Name : Y.S.El-Saman Address : Department of Mathematics, Faculty of Science, Jazan University, Saudi Arabia
Name : M. Abdel-Aty Address : Zewail City of Science and Technology, University of Science and Technology, 6th October, Giza, Egypt
Name : S.Abdel-Khalek Address : Department of Mathematics, Faculty of Science, Sohag University, Egypt
Name : I. Mechai Address : Department of Mathematics, Faculty of Science, Jazan University, Saudi Arabia
Accepted : 12/30/2015 4:34:00 AM
Abstract :
In this work, we study the interaction between three level atom and optical field initially prepared in squeezed coherent state. The dynamical properties of the geometric phase and non-local correlation will be compared in the absence and presence of the rotating wave approximation. The effect of the squeeze parameter on the evolution of the geometric phase and entanglement measured by the von Neumann entropy will be examined. Finally we explore the relationship between the geometric phase and entanglement during the time evolution.
Ref : 146
Title : Geometric phase and entanglement of three-level atom with and without rotating wave approximation
Author(s) :
Name : Y.S.El-Saman Address : Department of Mathematics, Faculty of Science, Jazan University, Saudi Arabia
Name : I. Mechai Address : Department of Mathematics, Faculty of Science, Jazan University, Saudi Arabia
Accepted : 12/30/2015 4:34:00 AM
Abstract :
In this work, we study the interaction between three level atom and optical field initially prepared in squeezed coherent state. The dynamical properties of the geometric phase and non-local correlation will be compared in the absence and presence of the rotating wave approximation. The effect of the squeeze parameter on the evolution of the geometric phase and entanglement measured by the von Neumann entropy will be examined. Finally we explore the relationship between the geometric phase and entanglement during the time evolution.
Ref : 145
Title : Instability criteria of a viscous liquid film
Author(s) :
Name : RamySalah Saber Selim Address : Tanta
Accepted : 12/28/2015 2:43:00 PM
Abstract :
In this work, we have investigated the instability criteria of a viscous liquid film flowing down an inclined slippery wall with a weak periodic corrugations. The mathematical model of the current problem is communicated with the linear as well as the nonlinear cases, in the frame of the long-wave theory. The fluid flow, due to the gravity, is assumed to be steady, and con fined to the limit of a small amplitude of the wall corrugation. The analysis has dealt with all the possible cases of resonance can be arised in the linear and nonlinear problems, corresponding to small wall corrugations. The eff ects of various parameters on the flow properties are examined through some numerical applications.
Ref : 144
Title : Bayesian estimation using MCMC approach on progressive first-failure censoring from inverse Weibull distribution
Author(s) :
Name : Hamda Saed Mohmel Alharthi Address : Mathematics Department, Faculty of Science, Taif University, Saudi Arabia
Accepted : 12/28/2015 2:42:00 PM
Abstract :
In this paper, we derive the maximum likelihood and Bayes estimation of the parameters of the inverse Weibull distribution (IWD) based on progressive first failure censored scheme. The Bayes estimator does not exist in an explicit form, so Markov Chain Monte Carlo (MCMC) method is used generate from the posterior distribution. The approximate confidence intervals as well as credible intervals for the parameters are presented. Numerical example will be used to illustrate this purposes. Results from the simulation studies will be used to assessing the performance of different method.
Ref : 142
Title : Statistical and bioinformatics analysis of 5′-regulatory region of TM4SF1 locus involved in cancer and drug resistance
Author(s) :
Name : Abdel-Salam Gomaa Address : Department of Mathematics, Statistics and Physics, CAS, Qatar University
Accepted : 12/27/2015 6:34:00 AM
Abstract :
Biostatistics and bioinformatics analyses are becoming integral to gene expression research. TM4SF1 gene expresses variably in various normal tissues and associated with carcinomas and drug resistant. Statistical analysis of TM4SF1 mRNA and protein measurements in various human tissues and tumors showed significant variation that could be linked to unique patterns of regulatory elements in the TM4SF1 alternative promoters. We identified six alternative promoters involved in expression of this gene, five located at the TM4SF1 5′-side, two overlapping promoters hosted CpG island (CGI), the other three alternative promoters also showed overlapping sequences and form a bidirectional promoter sequence involved in expression of TM4SF1 and divergently paired lncRNA locus TM4SF1-AS1. One promoter rich in TATA motifs was identified at the 3′-end of TM4SF1 locus. Structural differences in regulatory sequences dignified by dinucleotide base stacking energy showed specific values correlated with the location of the transcription binding sites (TFBSs). Further, several stem-loops were identified in the secondary structure of TM4SF1 and lnc-RNA TM4SF1-AS1 transcripts sequences that suggest possible posttranscriptional role of lnc-RNA in regulation of TM4SF1. Our findings give further insight into the roles played by TM4SF1 regulatory sequences in oncogenesis and drug resistance.
Ref : 141
Title : γ-Closed Spaces and Γ-Continuous Functions
Author(s) :
Name : Arafa A. Nasef Address : Department of Physics and Engineering Mathematics, Faculty of Engineering, Kafr El-Sheikh University, Kafr El-Sheikh, Egypt.
Name : M. M. El-Sharkasy Address : Department of Mathematics, Faculty of Science, Tanta University, Tanta, Egypt.
Accepted : 12/25/2015 12:38:00 AM
Abstract :
This paper introduces and studies a new class of functions between topological spaces, namely Γ-continuous functions, which properly contains the class of s-continuous functions introduced by the first author et al.[2]. Several results of [2] are improved and generalized.
Ref : 140
Title : a study of moon escaping phenomenon
Author(s) :
Name : Esraa Hussain Hashem Address : Aswan university faculty of Commerce
Accepted : 12/24/2015 10:03:00 AM
Abstract :
At this paper we discuss the moon escaping phenomena through the relationship between the distance between the earth and the moon and the earths inclination axis after these calculations we reached the moon period with the earth .
Ref : 139
Title : Advanced Topics in Statistical Analysis using SPSS
Author(s) :
Name : Abdel-Salam Gomaa Address : Department of Mathematics and Statistics, CAS, Qatar University
Accepted : 12/22/2015 5:29:00 AM
Abstract :
This workshop is designed to provide advanced and common statistical techniques in various disciplines which are very important for researches and practitioners using the SPSS. The workshop is designed especially to demonstrate some techniques and applications of biostatistics in medical, biology, business, Mass Communication, Engineering, public health, Epidemiology, pharmaceutical and biomedical fields.
For Whom: PhD scholars, faculty, employees and empirical researchers
The following topics will be dealt with in the workshop:
1. Introduction to the Inferential Statistics and SPSS.
2. Perform Hypothesis Testing and Confidence interval analysis for one and two populations.
3. One and Two-way Factorial ANOVA with SPSS.
4. Post Hoc Multiple Comparisons
5. Conducted a Pearson correlation and created a scatter plot for the results.
6. Perform Linear Regression Analysis (Simple and Multiple) and Logistic Regression.
7. Data Reduction Techniques (Factor Analysis, PCA,….etc.)
8. How to interpret the SPSS outputs and get the results into the report.
Ref : 138
Title : Dynamic Littlewood-Type Inequalities on Time Scales
Author(s) :
Name : Samir H. Saker Address : Department of Mathematics, Mansoura University
Accepted : 12/20/2015 2:19:00 AM
Abstract :
This talk is concerned with some dynamic inequalities on time scales. As special cases, these results contain and improve some integral inequalities and some discrete inequalities formulated by Littlewood in connection with some work on the general theory of orthogonal series. Also we show that the so-called "sneak-out principle" for discrete inequalities is valid also on a general time scale. In particular, we prove some new dynamic inequalities on time scales which as special cases contain discrete inequalities obtained by Bennett and Grosse-Erdmann. The main results also are used to formulate the corresponding continuous integral inequalities, and these are essentially new. The techniques employed in this paper are elementary and rely mainly on the time scales integration by parts rule, the time scales chain rule, the time scales Hölder inequality, and the time scales Minkowski inequality.
AMSSC: 26D10, 26D15, 34A40, 34N05, 39A12, 39A13
Keywords: Littlewoods inequality, time scales, dynamic inequality
Ref : 137
Title : Estimation in step-stress partially accelerated life tests for the Chen distribution using Progressive Type-II Censoring
Author(s) :
Name : Soliman, A. A. Address : Faculty of Science, Islamic University, Madinah, KSA
Name : Abd-Elmougod G. A Address : Faculty of Science, Taif University, Taif, KSA.
Name : Al- Sobhi, M.M. Address : Faculty of Applied Science, Umm Al-Qura University, Makkah, KSA.
Accepted : 12/19/2015 4:07:00 PM
Abstract :
In this paper, step-stress partially accelerated life tests are considered when the lifetime of a product follows a two-parameter bathtub-shaped lifetime distribution (Chen Distribution). Based on progressive Type-II censoring, the maximum likelihood estimates (MLEs) are obtained for the distribution parameters and acceleration factor. In addition, asymptotic variance and covariance matrix of the estimators are given. Approximate confidence intervals and the bootstrap confidence intervals for the distribution parameters and acceleration factor are given. An iterative procedure is used to obtain the estimators numerically using (Mathematica Package). A numerical example is presented to illustrate the method of estimation developed here. Finally, a Monte Carlo Simulation study is performed to check the statistical properties of estimates of the parameters and the confidence intervals.
Ref : 136
Title : PSEUDO-SLANT SUBMANIFOLDS OF A NORMAL PARACONTACT METRIC MANIFOLD
Author(s) :
Name : süleyman dirik Address : Amasya ünv.
Name : mehmet Atçeken Address : Gaziosmanpasa ünv.
Name : ümit yıldırım Address : Gaziosmanpasa ünv.
Accepted : 12/19/2015 4:07:00 PM
Abstract :
In this paper, the geometry of pseudo-slant submanifolds of a normal paracontact metric manifold are studied. We research integrability conditions for the distributions which are involved in the definition of a pseudo-slant submanifold. The necessary and sufficient conditions are given for a pseudo-slant submanifold to be pseudo-slant product.
Ref : 135
Title : A construction of non-gaussian white noise analysis using the theory of hypercomplex systems
Author(s) :
Name : M. Zakarya Address : Faculty of Science, Al-Azhar University, Assiut, Egypt
Name : Hossam A. Ghany Address : Faculty of Science Taif University, Taif, Saudi Arabia
Name : Abd-Allah Hyder Address : Faculty of Engineering, Al-Azhar University, Cairo, Egypt
Accepted : 12/19/2015 4:07:00 PM
Abstract :
In this paper, we present a generalization of white noise analysis to the case of non-Gaussian
measures. For this purpose, we use a biorthogonal approach in which instead of the exponentials
the characters of commutative hypercomplex systems are employed. Moreover, we construct
the elements of Wick calculus in a non-Gaussian setting.
Ref : 134
Title : Novel approach for scheduling on parallel identical machines
Author(s) :
Name : Omar Selt Address : Department of Mathematics, University of Msila
Accepted : 12/19/2015 4:08:00 PM
Abstract :
In this paper, we propose novel approach for solving scheduling problem of n tasks on m parallel identical machines. this problem is NP-complete in the strong sense and finding an optimal solution appears unlikely.This problem is formulated as an integer linear programming model with integer and deterministic data. Extensive computational experiment were performed which gave promising results in this work.
Ref : 133
Title : Some tasks of quantum Fisher information in two-qubit entanglement in the framework of quantum state estimation
Author(s) :
Name : S. Abdel-Khalek Address : Mathematics Department, Faculty of Science, Taif University, Taif, Saudi Arabia
Name : M. A. El-Sayed Address : Department of Computer Science, CIT College, Taif University, Taif, Saudi Arabia
Name : G. A. Abd-Elmougod Address : Department of Computer Science, CIT College, Taif University, Taif, Saudi Arabia
Accepted : 12/15/2015 2:51:00 PM
Abstract :
In this paper, we have discussed the quantum entanglement between two-two level atoms and optical coherent field as well as the atom-atom entanglement and their relationship with the quantum Fisher Information based on the quantum state estimation. Analytic results under certain parametric conditions are obtained, by means of which we have analyzed the influence of different parameters on the entanglement measures and quantum Fisher information for two types of the estimator parameter. Also, we have investigated the quantum Fisher information flow and nonlocal correlation between the two qubits which is measured by the concurrence and the entanglement between the two qubits and optical field which is measured by the von Neumann entropy in terms of the parameters involved in the whole system. The effect of the atomic motion in terms of velocity parameter in the evolution of the system dynamics; nonlocal correlation and quantum Fisher information have been discussed.
Ref : 132
Title : THE SOLITON INTERACTION IN WEAKLY NONLOCAL NONLINEAR MEDIA ON THE EXTERNAL POTENTIALS.
Author(s) :
Name : Nor Amirah bt Mohd Busul Aklan Address : Department of Computational and Theoretical Sciences, Faculty of Science, International Islamic University Malaysia, 25200 Kuantan, Malaysia
Name : Bakhram Umarov Address : Department of Physics, Faculty of Science, International Islamic University Malaysia, 25200 Kuantan, Malaysia
Accepted : 12/15/2015 8:56:00 AM
Abstract :
This paperwork had observed the analytical and numerical study of the solitons interaction and scattering of the weakly nonlocal nonlinear media on the external potential called delta potential. Using Nonlinear Schrodinger Equation (NLSE) in weakly nonlocal nonlinear media, we applied the variational approximation method to derive the equations for soliton parameters evolution during scattering process. Then a direct numerical simulation of NLSE is used to check the validity of approximations, considering the soliton initially located far from potential. Depending on initial velocity of the soliton, the phenomenon of reflection and transmission of the soliton through the potential have been showed. The critical values of the velocity separating these two scenarios have been identified.
Ref : 131
Title : Statistical Analysis of time series data using Error correction model
Author(s) :
Name : Amhammed Almhdi Abdallah Address : Faculty of Education Brack–Sebha University–Libya
Name : Nuri Omar Ali Address : Department of Statistics Faculty of Science Sebha University-Libya
Accepted : 12/15/2015 8:56:00 AM
Abstract :
The aim of this paper is to analyze the monthly and annual data for the temperature and hours of sunshine rays and humidity to the Libyan city of Sebha; for the purpose of testing the existence of unit root and the long-term relations of causality; using error correction model and the concept of cointegration
Ref : | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4690789580345154, "perplexity": 2077.898284061207}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-13/segments/1552912202689.76/warc/CC-MAIN-20190322200215-20190322222215-00234.warc.gz"} |
http://math.stackexchange.com/users/1489/whuber?tab=activity&sort=all&page=2 | # whuber
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Consultant (environmental and spatial stats a specialty), expert witness, and teacher. I can be reached through (outdated but still valid) links posted on my web site.
Twitter: @WilliamAHuber // ASA-P website: http://amstatphilly.org/
Why waste time learning, when ignorance is instantaneous?
--T(iger) Hobbes.
For any complex problem there is a simple solution. And it's always wrong.
--[Mis?]attributed to H.L. Mencken by Dava Sobel, Longitude.
# 548 Actions
Jul30 answered How to simplify a sum with binomial coefficients multiplied by $k^3/2^k$? Jul5 comment Combinatorics: Mean and Variance of an indicator function of items arranged in a circle. You have hit on the crux of the matter: the question, to be unambiguous, must somehow include enough information to enable calculation of all probabilities. In some settings those probabilities are given explicitly, but usually some particular process whereby the randomization is achieved is described. When the process consists of placing each blue ball within one of the spaces between red balls, all with equal probability (of $1/15$), and doing so in a way that the placement of one blue ball affects no other blue balls, you get the multinomial probabilities. Jul5 comment Combinatorics: Mean and Variance of an indicator function of items arranged in a circle. Perhaps an illustration would help. In the case $n=k=2$ there are two distinguishable configurations modulo symmetries of the circle: RBRB (red-blue-red-blue in counterclockwise order) and RBBR. In the multinomial scenario both are assumed to have probability $1/2$, while in the permutation scenario they are assumed to have probabilities $1/3$ and $2/3$, respectively. Some people have argued that absent any additional information, one should assume the maximum-entropy distribution. That's the multinomial one in this case--not the permutation one! Jul5 comment Combinatorics: Mean and Variance of an indicator function of items arranged in a circle. Yes I can still come up with two (and even more) solutions. In this post I have explained two ways of looking at the situation that are perfectly consistent with the problem. If you disagree, the burden is on you to demonstrate how one (or even both!) violate some explicitly-stated criterion in the problem statement. I would even go so far as to accept that there are some conventional implicit criteria in questions like this one: the obvious one is that the distribution ought to be invariant under symmetries of the configuration. That is the case in both scenarios. Jul5 comment Combinatorics: Mean and Variance of an indicator function of items arranged in a circle. No, that's not right. "Random" is not a quantitative characterization: you have to specify the process involved. The problem statement does not give enough information to "assess" a unique distribution. Both my answers are correct given their assumptions about how the balls are distributed randomly. One of them happens to agree with yours, but that only means it likely adopted the same assumptions you did. Jul5 revised Combinatorics: Mean and Variance of an indicator function of items arranged in a circle. added 4099 characters in body Jul3 answered Combinatorics: Mean and Variance of an indicator function of items arranged in a circle. Jul1 comment How to understand Demartines theorem This is a minor variant of the Central Limit Theorem, which asserts the standardized version of $||X||_2^2$ is asymptotically Normal. It requires that $X$ have finite variance. Jun26 comment Transforming vector elements to element indices Because matrix operations represent linear transformations and the relationship between Y and X is not linear, no such Q exists. Jun18 comment Does affine equivariance implies shape unbiasedness? Some things to consider: when $\sigma(X)=0$ (the $p\times p$ zero matrix) the procedure is trivially equivariant but obviously not unbiased. More generally, when $\sigma$ is equivariant unbiased and $p\gt 1$, the procedure $\tau(X)=\lambda\sigma(X)$ is also equivariant but when $\lambda^p\ne \lambda$ it must be biased. This suggests that dividing $\sigma(X)$ by its determinant might not be the right definition of "unbiased" to be using. Apr7 comment Holder's inequality Your second statement is not well defined until you assume both $X$ and $Y$ are strictly positive. Mar7 reviewed Approve another question on surds and how to use math symbols in this site Feb26 comment Lower bound for non-negative definite matrix The matrix $$\left( \begin{array}{cc} 0 & 1 \\ -1 & 2 \\ \end{array} \right)$$ is non-negative definite but your expression equals $-2$. Perhaps you would like to stipulate that $A$ also be symmetric? Feb16 awarded Good Answer Jan16 awarded Custodian Jan16 reviewed Leave Open How do you find the angle between a diagonal of a cube and one of its faces? Jan16 reviewed Looks OK How do you find the angle between a diagonal of a cube and one of its faces? Jan16 reviewed Looks OK Integration Techniques - Adding [arbitrary] values to the numerator. Jan16 reviewed Approve Card game question Dec16 comment Determine the number of revolutions the normal to a curve makes as it moves along a curve in three dimensions? That is correct, which is why I claimed your question is not well-defined! It only becomes so once you fix a pair of points on the sphere once and for all. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8578932881355286, "perplexity": 561.3363113111831}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-52/segments/1418802768636.90/warc/CC-MAIN-20141217075248-00175-ip-10-231-17-201.ec2.internal.warc.gz"} |
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http://community.boredofstudies.org/showthread.php?s=&goto=lastpost&threadid=375098 | # Thread: logarithm and exponential calculus
1. ## logarithm and exponential calculus
So I missed out a couple of weeks on maths and missed out quite a bit
I don't understand what is this "In" thing in the questions. I only have formulas with either "log" and "x", "d", "v" signs.
https://prnt.sc/hjyiz4
image1 (1).JPG
These questions are the ones I'm stuck on. I don't need all of them done, I just need someone to use one of the examples and explain it? The words in blue are the answers. pls help if you can
2. ## Re: logarithm and exponential calculus
ln is natural log, i.e. it has a base of e instead of 10 like log.
For differentiating you have ln(f(x)) so the derivative is f'(x)/f(x).
For integrating you want to divide by the derivative of the power. Note for 4a that isn't possible as it has lnx rather than a form of x e.g. 4x so consider indice laws. A good thing to note is that e^lnx = x and ln(e^x) as they are the inverse of each other.
NOTE: 2lnx = ln(x^2) but I'm assuming you know your log laws
3. ## Re: logarithm and exponential calculus
Originally Posted by otakuworld
So I missed out a couple of weeks on maths and missed out quite a bit
I don't understand what is this "In" thing in the questions. I only have formulas with either "log" and "x", "d", "v" signs.
https://prnt.sc/hjyiz4
image1 (1).JPG
These questions are the ones I'm stuck on. I don't need all of them done, I just need someone to use one of the examples and explain it? The words in blue are the answers. pls help if you can
woah this isn't something you should do when you've just started learning it.
But anyways in 4a) you need to know your indices and log law well.
$\int e^{2-lnx} \ dx = \ \ \int \ e^2 e^{-lnx} \ \ dx = \\ \\ e^2 \int e^{ln\frac{1}{x}} \ \ dx \\ \\ = e^2 \int \frac{1}{x} \ \ dx \\ \\ = e^2 ln(x) + C$
P.S holy crap you posted this at 4:10 am?!!
4. ## Re: logarithm and exponential calculus
thank you! and I didn't realise you could see the time I was up...shhh..ಠ_ಠ
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## gator8boy Group Title whats pie 11 months ago 11 months ago Edit Question Delete Cancel Submit
• This Question is Open
1. Chrisma
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pi = 3.14
• 11 months ago
2. Heyhihellowazap
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it be 3.14
• 11 months ago
3. e.mccormick
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$$\pi = \dfrac{c}{d}$$ where c is the circumference of a circle and d is the diameter of the same circle.
• 11 months ago
4. silverxx
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3.14
• 11 months ago
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Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9979802966117859, "perplexity": 24192.734855106173}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-42/segments/1413507444385.33/warc/CC-MAIN-20141017005724-00056-ip-10-16-133-185.ec2.internal.warc.gz"} |
http://stackoverflow.com/questions/642265/start-does-not-work-in-bat-file-when-used-as-filetype-handler-in-firefox | # “start” does not work in bat file when used as filetype handler in Firefox
I have a batch (bat / cmd) file which should act as a filetype handler for jpeg files in Firefox, I just want it to copy the file to another folder, and then open the file in the Picasa Viewer. When I run it from the command line, even if I'm running it from another folder, it works fine, and opens Picasa Viewer. However, when setting it as the handler for jpeg files in Firefox, it only copies the file, but does not start Picasa.
Here is the script (I'm not a batch programmer so this could probably be a lot simpler, was just scraped together from various stackoverflow posts...):
``````set topath=%~DP0
copy %1 "%topath%"
@echo off
set picpath=%1
set picpath=%picpath:\=;%
set picpath=%picpath: =:%
for /F "tokens=* delims=;" %%i IN (%picpath%) DO call :LAST_FOLDER %%i
goto :EOF
:LAST_FOLDER
if "%1"=="" (
set LAST2=%LAST::= %
start explorer "%topath%"
goto :EOF
)
set LAST=%1
SHIFT
goto :LAST_FOLDER
``````
(I also tried opening just explorer on the folder, as seen above.) So, anyone know why neither explorer nor Picasa get started when run from Firefox, but both get started from the console? (Also, explorer gets started when drag-dropping a file on the script, however, Picasa does not...)
-
This "feature/bug" I have seen a number of times when using the start command.
The start command is interpreting the the first parameter as the "title" .
Just try this for example : start "c:\windows\system32\calc.exe" "c:\windows\system32\notepad.exe"
It will launch notepad, not calculator
So simply prepend a dummy parameter like this : start "some dummy title" "c:\windows\system32\calc.exe"
It will work fine...
-
Now you got my hopes up... I couldn't get this to work either.. (I mean, the weird thing is how it works from the commandline but not from Firefox...) – unhammer Mar 28 '09 at 11:32
Looking at your code (Damn, is there a way to copy/paste with the correct alignment on this site? :( ) something like this might help:
jpgviewer.cmd
``````@echo off
set topath=%~dp0
copy %1 "%topath%"
set file=%~nx1
start explorer "%topath%"
start "-" "%Programfiles%\Google\Picasa3\PicasaPhotoViewer.exe" "%topath%%file%"
``````
Hope this helps.
%~nx0 : Gets the filename+ext of the given variable (here 0) Too bad you didn't see it, it't at the samne place you got ~dp part (help of for).
-
I haven't read it thorough enough to understand it but your path to picasa looks wrong rather than c:\program files\ you have c:\programfiler\
HTH
-
I think this is Norwegian for "Program files". – Daniel Rikowski Mar 13 '09 at 11:51
Yeah, for some reason MS decided to localize system directories..silly. – unhammer Mar 28 '09 at 11:30
Use the environment variable ProgramFiles instead, ex. %ProgramFiles% – RealHowTo Jun 20 '09 at 13:06
You may try substituting `start` by `cmd /c start`. Maybe that helps. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8113576173782349, "perplexity": 10492.290514905739}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-10/segments/1394678694630/warc/CC-MAIN-20140313024454-00016-ip-10-183-142-35.ec2.internal.warc.gz"} |
http://math.stackexchange.com/questions/20957/showing-fraceaxb2-cosbxa2-cosbxa2b2-eax-cosbx | # Showing $\frac{e^{ax}(b^2\cos(bx)+a^2\cos(bx))}{a^2+b^2}=e^{ax}\cos(bx).$
I've got:
$$\frac{e^{ax}(b^2\cos(bx)+a^2\cos(bx))}{a^2+b^2}.$$
Could someone show me how it simplifies to:
$e^{ax} \cos(bx)$?
It looks like the denominator is canceled by the terms that are being added, but then how do I get rid of one of the cosines?
-
Notice b^(2)cos(bx)+a^(2)cos(bx)=(a^2+b^2)(cos(bx)) – yunone Feb 8 '11 at 7:54
Someone should edit this title! – user2468 Feb 8 '11 at 8:14
You use the distributive law, which says that $(X+Y)\cdot Z=(X\cdot Z)+(Y\cdot Z)$ for any $X$, $Y$, and $Z$. In your case, we have $X=b^2$, $Y=a^2$, and $Z=\cos(bx)$, and so
$$\frac{e^{ax}(b^2\cos(bx)+a^2\cos(bx))}{a^2+b^2}=\frac{e^{ax}((b^2+a^2)\cos(bx))}{(a^2+b^2)}=\frac{e^{ax}((a^2+b^2)\cos(bx))}{(a^2+b^2)}=e^{ax}\cos(bx).$$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9586119055747986, "perplexity": 244.25116679523944}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-32/segments/1438042990603.54/warc/CC-MAIN-20150728002310-00245-ip-10-236-191-2.ec2.internal.warc.gz"} |
https://www.clingenetic.com.ua/component/k2/item/11-mitochondria-and-male-disease.html | Понеділок, вересня 28, 2020
# Mitochondria and male disease.
Frank, S. A. and Hurst, L. D. 1996. Mitochondria and male disease.
Nature 383:224.
Mitochondrial mutations have been clearly associated with a wide range of degenerative conditions, including blindness caused by Leber's Hereditary Optic Neuropathy and various muscle and heart conditions in Maternally Inherited Myopathy and Cardiomyopathy. Recent data suggest an even broader array of maladies associated with mitochondrial mutations and poor aerobic performance, from Parkinson and Alzheimer diseases to reduced sperm motility and male infertility (reviewed in ref. 1). Mitochondria are transmitted matrilineally in most organisms. Matrilineal inheritance creates an important and previously unnoted male-female asymmetry in the expected severity of mitochondrial disease. Consider a germline mitochondrial mutation with severe effects on males but only mild effects on females. This mutation could increase to relatively high frequency because natural selection of mitochondria occurs only in females. Males do not transmit mitochondria, and therefore male-specific phenotypes have no fitness consequences for mitochondria. Simple models of population genetics describe the quantitative effects of this male-female asymmetry. The equilibrium frequency of germline mitochondrial mutations is approximately $q=\m/\sf$, where $\m$ is the mitochondrial mutation rate in the female germline, and $1-\sf$ is the fitness of a female with the mutation relative to a normal female with a fitness of one. A male carrying the mitochondrial mutation has a relative fitness of $1-\sm$ when compared with a normal male with a fitness of one. For example, if a mutation arose with frequency $\m=10^{-4}$, with severe effects on sperm motility and a reduction in male fertility by one-half $(\sm=0.5)$ but only mild effects on females $(\sf=0.01)$, then $q=\m/\sf=0.01$. This mutation, occurring at an equilibrium frequency of one percent of the population, would have strong fitness consequences for males but negligible effects on females. At least one maternally inherited mitochondrial disease affects males more severely than females. Approximately 85 percent of individuals affected by Leber's Hereditary Optic Neuropathy (LHON) are male [1]. Several distinct base-pair substitutions in germlinemtDNA have been directly associated with LHON. Linkage analysis suggested that a deleterious X-linked mutation in combination with defective mitochondria may be the cause of the sex bias [2]. However, several further studies failed to support a model of X-linkage (see, for example, ref. 3). An analysis of X-inactivation also argues against X-linkage as the cause of sex-bias [4]. Furthermore, LHON typically has an earlier age of onset in males than females. Present evidence therefore suggests that males are more susceptible to the mitochondrial defects. In another example, an inherited mitochondrial mutation was associated with early onset Pearson marrow-pancreas syndrome in a male (high $\sm$) but only late onset, progressive eye disease in the mother (low $\sf$) [5]. Finally, a mother and her two sons shared a tendency for spontaneous, somatic deletions in mtDNA [6]. The mother was asymptomatic but the two sons were severely affected by anemia and mitochondrial myopathy. This suggests that males may be more susceptible than females to certain mitochondrial defects. Male-female dimorphism of mitochondrial effects is possible in various organs, such as the heart. The difference between the sexes is likely to be small, but perhaps significant. Ascertainment will be difficult because there is undoubtedly a wide spectrum of mutations, many with highly correlated effects on the sexes (high correlation between $\sm$ and $\sf$). However, natural selection creates an asymmetric sieve, pushing down in frequency any mutations with high $\sf$ values but allowing through mutations with high $\sm$ but low $\sf$. This selective sieve may explain some aspects of male-female dimorphism in heart disease and other degenerative syndromes. Sperm vigour and male fertility are traits that deserve close study. Sperm obtain energy for motility from a densely packed group of mitochondria at the base of the flagellum [7]. Almost all energy produced by this pack of mitochondria is used to drive the flagellum and propel the sperm. Reduced power output translates directly into reduced motility and probably into reduced fertility. This tight coupling between capacity and performance differs from most tissues, which function reasonably well when mitochondrial capacity is reduced by as much as 80 or 90 percent. Disease is observed only when mitochondrial function drops below a threshold of 10 or 20 percent of full capacity [1]. Aberrations in sperm motility and male fertility are widely observed in humans and other species [8]. Such traits are puzzling given the powerful selection against alleles with deleterious effects on fertility. Sperm dysfunction may be explicable, however, if mitochondrial mutations arise that strongly affect sperm vigour but have only weak effects on female fitness. Both somatic mtDNA deletions [8,9] and inherited mitochondrial disease [10] have been associated with reduced sperm motility and poor fertility. Whether inherited mutations are sufficiently frequent to be an important cause of infertility will depend on the correlated fitness effect of these mutations when in females (the correlation between $\sf$ and $\sm$). The logic of the population genetics argument is indisputable. The important questions are how frequently mutations with $\sm>\sf$ arise, and to what extent male infertility or excess mortality can be explained by such mutations. Rapid progress on the mitochondrial genetics of humans and mammalian models will provide some clues in the near future. Experiments and screens of natural populations of {\it Drosophila} can supplement the mammalian data. Mutagenesis experiments could provide data on the correlation between $\sm$ and $\sf$ for new mutations, with particular attention to sperm dysfunction. Mutagenesis followed by laboratory cage experiments could be used to examine the idea of a selective sieve, comparing the distribution of $\sm$ and $\sf$ in new mutations relative to the distribution after selection. These model systems can also be used to study how frequently compensatory nuclear changes mask male-specific mitochondrial defects. Male-female dimorphism of mitochondrial disease is a subset of a larger problem. Many symbiotic microorganisms are transmitted matrilineally [11]. The function of these symbionts in males varies widely. The broad problem can be described as the competence of uniparentally inherited symbionts in the nontransmitting sex. Once viewed in this way, many interesting puzzles emerge.
Інші матеріали у цій категорії: « Genetic counseling for mitochondrial disorders Mitochondrial disease » | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6634091734886169, "perplexity": 4764.294058024704}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-40/segments/1600401600771.78/warc/CC-MAIN-20200928104328-20200928134328-00726.warc.gz"} |
http://mathhelpforum.com/advanced-algebra/86637-matrix-question-print.html | # Matrix question
• Apr 30th 2009, 08:55 AM
mathatlast
Matrix question
Hi. I need help with the final paer of this question. I am including my answers so far. Thanks in advance.
For the given martix A,
[-4 1 1]
[1 5 -1]
[0 1 -3]
a. Find the characteristic polynomail -60+x^3+2x^2-23x
b. Find the eigenvalues 5,-4,-3
c. Find the eigenvectors
[5] [1 1 10]
[-3] [8 0 -1]
[-4] [1 1 1]
The final part is where I need the help- or so I think!- If A is diagonalizable find a matrix P such that P^-1 AP is diagonal.
I just cannot figure it out.
Thanks again in advance.
• Apr 30th 2009, 06:11 PM
Gamma
You have done all the work. Simply make P the matrix with first column the eigenvector corresponding to the 1st eigenvalue, the second column the eigenvector corresponding to the second eigenvalue, ditto for the third.
This will give you the diagonal matrix with entries 1st eigenvalue, second eigenvalue, third eigenvalue when you do $P^{-1}AP$. This is in fact the Jordan Canonical Form of your matrix A, and it is unique up to permutation of the blocks (which in this case consist of just the eigenvalue).
So you can see in this way that you could put those columns in any order you want and you would just get a different diagonal matrix (ie just a permutation of the eigenvalues) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 1, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9567406177520752, "perplexity": 653.3566942371208}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-40/segments/1474738661367.29/warc/CC-MAIN-20160924173741-00265-ip-10-143-35-109.ec2.internal.warc.gz"} |
http://mathhelpforum.com/advanced-algebra/91224-subspaces-print.html | # Subspaces
• May 31st 2009, 01:34 AM
Robb
Subspaces
Hello MHF, would appreciate some help with the following equestions;
Determine which of the following sets are subspaces. Give reasons for your answers.
(a) $H=\left\{\left[\begin{array}{cc}s\\2s\\0\end{array}\right]:s\in\mathbb{R},s\geq0 \right\}$
(b) $L=\left\{\left[\begin{array}{cc}s+2t+1\\s+3t\end{array}\right]:s,t\in\mathbb{R} \right\}$
• May 31st 2009, 02:20 AM
Moo
Hello,
Quote:
Originally Posted by Robb
Hello MHF, would appreciate some help with the following equestions;
Determine which of the following sets are subspaces. Give reasons for your answers.
You have to check that for any u,v belonging to the set, u+v belongs to the set, and for any real number $\lambda$ , $\lambda u$ belongs to the set.
Quote:
(a) $H=\left\{\left[\begin{array}{cc}s\\2s\\0\end{array}\right]:s\in\mathbb{R},s\geq0 \right\}$
So let $u=\begin{bmatrix} s\\2s\\0 \end{bmatrix}$ and $v=\begin{bmatrix} s'\\2s'\\0\end{bmatrix}$, where $s,s' \in\mathbb{R}$ and $\geq 0$.
$u+v=\begin{bmatrix} s+s' \\ 2(s+s') \\ 0 \end{bmatrix}$
Does this belong to $H$ ?
$\lambda\in\mathbb{R}$
Consider the case when $\lambda< 0$
Quote:
(b) $L=\left\{\left[\begin{array}{cc}s+2t+1\\s+3t\end{array}\right]:s,t\in\mathbb{R} \right\}$
Let $u=\begin{bmatrix}s+2t+1\\s+3t\end{bmatrix}$ and $v=\begin{bmatrix}s'+2t'+1\\s'+3t'\end{bmatrix}$
$u+v=\begin{bmatrix} (s+s')+2(t+t')+2\\(s+s')+3(t+t') \end{bmatrix}$
Can the first coordinate be in the form $m+2n+{\color{red}1}$ ?
The problem here is that s and t are the same in the first and the second coordinates.
If there weren't, you could have just written $(s+s'+1)+2(t+t')+1$
But you would have to get $(s+s'+1)+3(t+t')$ as your second coordinate...
• May 31st 2009, 02:26 AM
HallsofIvy
Quote:
Originally Posted by Robb
Hello MHF, would appreciate some help with the following equestions;
Determine which of the following sets are subspaces. Give reasons for your answers.
(a) $H=\left\{\left[\begin{array}{cc}s\\2s\\0\end{array}\right]:s\in\mathbb{R},s\geq0 \right\}$
(b) $L=\left\{\left[\begin{array}{cc}s+2t+1\\s+3t\end{array}\right]:s,t\in\mathbb{R} \right\}$
A subset of a vector space is a subspace if and only if it is "closed" under vector addition and scalar multiplication.
If u and v are two members of H, they are of the form $u= \left[\begin{array}{c}s \\ 2s \\ 0\end{array}\right]$ and $v= \left[\begin{array}{c}t\\ 2t\\ 0\end{array}\right]$ for some positive numbers s and t. Their sum is $u+ v=\left[\begin{array}{c}s+t \\ 2s+ 2t \\ 0\end{array}\right]=\left[\begin{array}{c}s \\ 2(s+t) \\ 0\end{array}\right]$ while, for any number k, $k v= \left[\begin{array}{c}ks \\ 2(ks) \\ 0\end{array}\right]$. What happens if k is negative?
If u and v are two members of L, they are of the form $u= \left[\begin{array}{c}s+ 2t+ 1 \\ s+ 3t\end{array}\right]$ and $v= \left[\begin{array}{c}x+ 2y+ 1 \\ x+ 3y\end{array}\right]$ where s, t, x, y can be any real numbers. Their sum is $u+ v= \left[\begin{array}{c}s+ 2t+ 1+ x+ 2y+ 1 \\ s+ 3t+ x+ 3y\end{array}\right]= \left[\begin{array}{c}(s+x)+ 2(t+y)+ 2 \\ (s+x)+ 3(t+y)\end{array}\right]$ and, for a real number k, $ku= \left[\begin{array}{c}k(s+ 2t+ 1) \\ k(s+ 3t)\end{array}\right]= \left[\begin{array}{c}ks+ 2kt+ k) \\ (ks+ 3lt)\end{array}\right]$. Can you see that those are NOT of the correct form for L?
• May 31st 2009, 02:28 AM
Moo
To Robb and HallsOfIvy : using \begin{bmatrix} ... \end{bmatrix} is shorter than going with arrays :) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 30, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9195427894592285, "perplexity": 376.6709605366251}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-32/segments/1438043058631.99/warc/CC-MAIN-20150728002418-00290-ip-10-236-191-2.ec2.internal.warc.gz"} |
http://mathoverflow.net/users/17118/davide-giraudo?tab=activity | Davide Giraudo
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https://www.science.gov/topicpages/a/air+bubble+radius.html | #### Sample records for air bubble radius
1. Rise of Air Bubbles in Aircraft Lubricating Oils
NASA Technical Reports Server (NTRS)
Robinson, J. V.
1950-01-01
Lubricating and antifoaming additives in aircraft lubricating oils may impede the escape of small bubbles from the oil by forming shells of liquid with a quasi-solid or gel structure around the bubbles. The rates of rise of small air bubbles, up to 2 millimeters in diameter, were measured at room temperature in an undoped oil, in the same oil containing foam inhibitors, and in an oil containing lubricating additives. The apparent diameter of the air bubbles was measured visually through an ocular micrometer on a traveling telescope. The bubbles in the undoped oil obeyed Stokes' Law, the rate of rise being proportional to the square of the apparent diameter and inversely proportional to the viscosity of the oil. The bubbles in the oils containing lubricating additives or foam inhibitors rose more slowly than the rate predicted by Stokes 1 Law from the apparent diameter, and the rate of rise decreased as the length of path the bubbles traveled increased. A method is derived to calculate the thickness of the liquid shell which would have to move with the bubbles in the doped oils to account for the abnoi'I!l8.lly slow velocity. The maximum thickness of this shell, calculated from the velocities observed, was equal to the bubble radius.
2. Rise velocity of an air bubble in porous media: Theoretical studies
Corapcioglu, M. Yavuz; Cihan, Abdullah; Drazenovic, Mirna
2004-04-01
The rise velocity of injected air phase from the injection point toward the vadose zone is a critical factor in in-situ air sparging operations. It has been reported in the literature that air injected into saturated gravel rises as discrete air bubbles in bubbly flow of air phase. The objective of this study is to develop a quantitative technique to estimate the rise velocity of an air bubble in coarse porous media. The model is based on the macroscopic balance equation for forces acting on a bubble rising in a porous medium. The governing equation incorporates inertial force, added mass force, buoyant force, surface tension and drag force that results from the momentum transfer between the phases. The momentum transfer terms take into account the viscous as well as the kinetic energy losses at high velocities. Analytical solutions are obtained for steady, quasi-steady, and accelerated bubble rise velocities. Results show that air bubbles moving up through a porous medium equilibrate after a short travel time and very short distances of rise. It is determined that the terminal rise velocity of a single air bubble in an otherwise water saturated porous medium cannot exceed 18.5 cm/s. The theoretical model results compared favorably with the experimental data reported in the literature. A dimensional analysis conducted to study the effect of individual forces indicates that the buoyant force is largely balanced by the drag force for bubbles with an equivalent radius of 0.2-0.5 cm. With increasing bubble radius, the dimensionless number representing the effect of the surface tension force decreases rapidly. Since the total inertial force is quite small, the accelerated bubble rise velocity can be approximated by the terminal velocity.
3. Elastic oscillations of bubbles separated from an air cavity in a magnetic fluid
Polunin, V. M.; Shabanova, I. A.; Karpova, G. V.; Kobelev, N. S.; Ryabtsev, K. S.; Platonov, V. B.; Aref'ev, I. M.
2015-07-01
The elastic oscillations of air bubbles separated from an air cavity compressed by the ponderomotive forces of a magnetic field in a magnetic fluid are accompanied by the appearance of an alternating magnetic field component. The frequency of the alternating component corresponds to the frequency of radial bubble oscillations, and this fact is used to determine the bubble size. A great body of experimental data has been obtained from six magnetic fluid samples with different viscosities. Based on these data, histograms illustrating the bubble radius distribution are plotted. The appearance of the alternating magnetic field component caused by bubble oscillations in a magnetized magnetic fluid can be used to develop a fundamentally new method for supplying small metered gas shots to a reactor, as well as to study the boiling process in a magnetic fluid.
4. The production of drops by the bursting of a bubble at an air liquid interface
NASA Technical Reports Server (NTRS)
Darrozes, J. S.; Ligneul, P.
1982-01-01
The fundamental mechanism arising during the bursting of a bubble at an air-liquid interface is described. A single bubble was followed from an arbitrary depth in the liquid, up to the creation and motion of the film and jet drops. Several phenomena were involved and their relative order of magnitude was compared in order to point out the dimensionless parameters which govern each step of the motion. High-speed cinematography is employed. The characteristic bubble radius which separates the creation of jet drops from cap bursting without jet drops is expressed mathematically. The corresponding numerical value for water is 3 mm and agrees with experimental observations.
5. Modelling of Air Bubble Rising in Water and Polymeric Solution
Hassan, N. M. S.; Khan, M. M. K.; Rasul, M. G.; Subaschandar, N.
2010-06-01
This study investigates a Computational Fluid Dynamics (CFD) model for a single air bubble rising in water and xanthan gum solution. The bubble rise characteristics through the stagnant water and 0.05% xanthan gum solution in a vertical cylindrical column is modelled using the CFD code Fluent. Single air bubble rise dispersed into the continuous liquid phase has been considered and modelled for two different bubble sizes. Bubble velocity and vorticity magnitudes were captured through a surface-tracking technique i.e. Volume of Fluid (VOF) method by solving a single set of momentum equations and tracking the volume fraction of each fluid throughout the domain. The simulated results of the bubble flow contours at two different heights of the cylindrical column were validated by the experimental results and literature data. The model developed is capable of predicting the entire flow characteristics of different sizes of bubble inside the liquid column.
6. Mixing of spherical bubbles with time-dependent radius in incompressible flows
Pérez-Muñuzuri, Vicente; Garaboa-Paz, Daniel
2016-02-01
The motion of contracting and expanding bubbles in an incompressible chaotic flow is analyzed in terms of the finite-time Lyapunov exponents. The viscous forces acting on the bubble surface depend not only on the relative acceleration but also on the time dependence of the bubble volume, which is modeled by the Rayleigh-Plesset equation. The effect of bubble coalescence on the coherent structures that develop in the flow is studied using a simplified bubble merger model. Contraction and expansion of the bubbles is favored in the vicinity of the coherent structures. Time evolution of coalescence bubbles follows a Lévy distribution with an exponent that depends on the initial distance between bubbles. Mixing patterns were found to depend heavily on merging and on the time-dependent volume of the bubbles.
7. Maximal Air Bubble Entrainment at Liquid-Drop Impact
Bouwhuis, Wilco; van der Veen, Roeland C. A.; Tran, Tuan; Keij, Diederik L.; Winkels, Koen G.; Peters, Ivo R.; van der Meer, Devaraj; Sun, Chao; Snoeijer, Jacco H.; Lohse, Detlef
2012-12-01
At impact of a liquid drop on a solid surface, an air bubble can be entrapped. Here, we show that two competing effects minimize the (relative) size of this entrained air bubble: for large drop impact velocity and large droplets, the inertia of the liquid flattens the entrained bubble, whereas for small impact velocity and small droplets, capillary forces minimize the entrained bubble. However, we demonstrate experimentally, theoretically, and numerically that in between there is an optimum, leading to maximal air bubble entrapment. For a 1.8 mm diameter ethanol droplet, this optimum is achieved at an impact velocity of 0.25m/s. Our results have a strong bearing on various applications in printing technology, microelectronics, immersion lithography, diagnostics, or agriculture.
8. Experiments of air bubbles impacting a rigid wall in tap water
Pelletier, Etienne; Béguin, Cédric; Étienne, Stéphane
2015-12-01
Trajectory and impact dynamics of bubbles in tap water were studied. Results confirm that bubbles with identical radii can be classified in two categories: fast bubbles and slow bubbles. Each category of bubble can describe zig-zag or helical motion. The aspect ratio and terminal velocity of a bubble depend on its radius and category. Restitution relations are also presented for the two categories of bubble after impact with an horizontal wall. With these relations, the state of a bubble after rebound can be predicted from its state before rebound. The aspect ratio before rebound of the bubble is found to play a key role in the dynamics of the impacts.
9. Effect of air, heliox, and oxygen breathing on air bubbles in aqueous tissues in the rat.
PubMed
1994-12-01
Our purpose was to examine the behavior of air bubbles in three non-lipid tissues (skeletal muscle, tendon, and the anterior chamber of the eye) during breathing of air, helium-oxygen (heliox, 80:20), or oxygen. Air bubbles were injected into skeletal muscle or tendon in rats after decompression from a 1-h air exposure at 3.5 atm abs (355 kPa) or into the anterior chamber of the rat eye without any previous pressure exposure. The bubbles were studied by photomicroscopy at 1 atm abs (101 kPa) during either air breathing or during air breathing followed by heliox or O2 breathing. Muscle: during air breathing, all bubbles initially increased in size for a period of 55-100 min after decompression and then started to shrink. Both heliox and O2 breathing increased the shrinking rate as compared to air. Bubble size decreased more rapidly during O2 than heliox breathing. Tendon: during air breathing, bubble size decreased at a constant rate; in one bubble the decrease was preceded by a small increase. During heliox breathing most bubbles decreased faster than during breathing of air. O2 breathing caused a short-term increase in bubble size in 4 out of 10 bubbles. Otherwise, the shrinkage rate was increased in six bubbles and uninfluenced in four bubbles during breathing of O2. Rat eye: during air breathing all bubbles shrank in the observation period. When heliox breathing was started, all bubbles transiently grew for 10-35 min, after which they began shrinking faster than during air breathing. When O2 breathing was started, five out of seven bubbles initially grew or stopped shrinking for 5-15 min, after which they decreased in size faster than during both air and heliox breathing. We conclude that breathing of either heliox or O2 will cause air bubbles in aqueous tissues to disappear faster than during breathing of air. Since heliox breathing promoted bubble shrinking in both muscle and tendon, gas exchange was probably not primarily limited by extravascular diffusion in
10. Entrapped air bubbles in piezo-driven inkjet printing: Their effect on the droplet velocity
de Jong, Jos; Jeurissen, Roger; Borel, Huub; van den Berg, Marc; Wijshoff, Herman; Reinten, Hans; Versluis, Michel; Prosperetti, Andrea; Lohse, Detlef
2006-12-01
Air bubbles entrapped in the ink channel are a major problem in piezo-driven inkjet printing. They grow by rectified diffusion and eventually counteract the pressure buildup at the nozzle, leading to a breakdown of the jetting process. Experimental results on the droplet velocity udrop as a function of the equilibrium radius R0 of the entrained bubble are presented. Surprisingly, udrop(R0) shows a pronounced maximum around R0=17μm before it sharply drops to zero around R0=19μm. A simple one-dimensional model is introduced to describe this counterintuitive behavior which turns out to be a resonance effect of the entrained bubble.
11. Light Scattering by Ice Crystals Containing Air Bubbles
Zhang, J.; Panetta, R. L.; Yang, P.; Bi, L.
2014-12-01
The radiative effects of ice clouds are often difficult to estimate accurately, but are very important for interpretation of observations and for climate modeling. Our understanding of these effects is primarily based on scattering calculations, but due to the variability in ice habit it is computationally difficult to determine the required scattering and absorption properties, and the difficulties are only compounded by the need to include consideration of air and carbon inclusions of the sort frequently observed in collected samples. Much of the previous work on effects of inclusions in ice particles on scattering properties has been conducted with variants of geometric optics methods. We report on simulations of scattering by ice crystals with enclosed air bubbles using the pseudo-spectral time domain method (PSTD) and improved geometric optics method (IGOM). A Bouncing Ball Model (BBM) is proposed as a parametrization of air bubbles, and the results are compared with Monte Carlo radiative transfer calculations. Consistent with earlier studies, we find that air inclusions lead to a smoothing of variations in the phase function, weakening of halos, and a reduction of backscattering. We extend these studies by examining the effects of the particular arrangement of a fixed number of bubbles, as well as the effects of splitting a given number of bubbles into a greater number of smaller bubbles with the same total volume fraction. The result shows that the phase function will not change much for stochastic distributed air bubbles. It also shows that local maxima of phase functions are smoothed out for backward directions, when we break bubbles into small ones, single big bubble scatter favors more forward scattering than multi small internal scatters.
12. Amateur scientists - producing light from a bubble of air
SciTech Connect
Hiller, R.A.; Barber, B.P.
1995-02-01
A glowing bubble of air cannot be bought anywhere at any price. But with an oscilloscope, a moderately precise sound generator, a home stereo amplifier and about \$100, readers can turn sound into light through a process called sonoluminescence. The apparatus is relatively simple. A glass spherical flask filled with water serves as the resonator - the cavity in which sound is created to trap and drive the bubble. Small speakers, called piezoelectric transducers, are cemented to the flask and powered by an audo generator and amplifier. Bubbles introduced into the water coalesce at the center of the flask and produce a dim light visible to the unaided eye in a darkened room.
13. The role of bubbles during air-sea gas exchange
Emerson, Steven; Bushinsky, Seth
2016-06-01
The potential for using the air-sea exchange rate of oxygen as a tracer for net community biological production in the ocean is greatly enhanced by recent accuracy improvements for in situ measurements of oxygen on unmanned platforms. A limiting factor for determining the exchange process is evaluating the air-sea flux contributed by bubble processes produced by breaking waves, particularly during winter months under high winds. Highly accurate measurements of noble gases (Ne, Ar & Kr) and nitrogen, N2, in seawater are tracers of the importance of bubble process in the surface mixed layer. We use measured distributions of these gases in the ventilated thermocline of the North Pacific and an annual time series of N2 in the surface ocean of the NE Subarctic Pacific to evaluate four different air-water exchange models chosen to represent the range of model interpretation of bubble processes. We find that models must have an explicit bubble mechanism to reproduce concentrations of insoluble atmospheric gases, but there are periods when they all depart from observations. The recent model of Liang et al. (2013) stems from a highly resolved model of bubble plumes and categorizes bubble mechanisms into those that are small enough to collapse and larger ones that exchange gases before they resurface, both of which are necessary to explain the data.
14. Technical Note: How accurate can stalagmite formation temperatures be determined using vapour bubble radius measurements in fluid inclusions?
Spadin, F.; Marti, D.; Hidalgo-Staub, R.; Rička, J.; Fleitmann, D.; Frenz, M.
2015-06-01
Stalagmites are natural archives containing detailed information on continental climate variability of the past. Microthermometric measurements of fluid inclusion homogenisation temperatures allow determination of stalagmite formation temperatures by measuring the radius of stable laser-induced vapour bubbles inside the inclusions. A reliable method for precisely measuring the radius of vapour bubbles is presented. The method is applied to stalagmite samples for which the formation temperature is known. An assessment of the bubble radius measurement accuracy and how this error influences the uncertainty in determining the formation temperature is provided. We demonstrate that the nominal homogenisation temperature of a single inclusion can be determined with an accuracy of ±0.25 °C, if the volume of the inclusion is larger than 105 μm3. With this method, we could measure in a proof-of-principle investigation that the formation temperature of 10-20 yr old inclusions in a stalagmite taken from the Milandre cave is 9.87 ± 0.80 °C, while the mean annual surface temperature, that in the case of the Milandre cave correlates well with the cave temperature, was 9.6 ± 0.15 °C, calculated from actual measurements at that time, showing a very good agreement. Formation temperatures of inclusions formed during the last 450 yr are found in a temperature range between 8.4 and 9.6 °C, which corresponds to the calculated average surface temperature. Paleotemperatures can thus be determined within ±1.0 °C.
15. An experimental study on resonance of oscillating air/vapor bubbles in water using a two-frequency acoustic apparatus
Ohsaka, K.
2003-05-01
A two-frequency acoustic apparatus is employed to study the growth behavior of vapor-saturated bubbles driven in a volumetric mode. A unique feature of the apparatus is its capability of trapping a bubble by an ultrasonic standing wave while independently driving it into oscillations by a second lower-frequency acoustic wave. It is observed that the growing vapor bubbles exhibit a periodic shape transition between the volumetric and shape modes due to resonant coupling. In order to explain this observation, we performed an experimental investigation on resonant coupling of air bubbles and obtained the following results: First, the induced shape oscillations are actually a mixed mode that contains the volume component, thus, vapor bubbles can grow while they exhibit shape oscillations. Second, the acoustically levitated bubbles are deformed and therefore, degeneracy in resonant frequency is partially removed. As a result, the vapor bubbles exhibit the shape oscillations in both the axisymmetric mode and asymmetric (three-dimensional) modes. Nonlinear effects in addition to the frequency shift and split due to deformation creates overlapping of the coupling ranges for different modes, which leads to the continuous shape oscillations above a certain bubble radius as the bubble grows.
16. Motion of Air Bubbles in Water Subjected to Microgravity Accelerations
NASA Technical Reports Server (NTRS)
DeLombard, Richard; Kelly, Eric M.; Hrovat, Kenneth; Nelson, Emily S.; Pettit, Donald R.
2006-01-01
The International Space Station (ISS) serves as a platform for microgravity research for the foreseeable future. A microgravity environment is one in which the effects of gravity are drastically reduced which then allows physical experiments to be conducted without the over powering effects of gravity. During his 6-month stay on the ISS, astronaut Donald R. Pettit performed many informal/impromptu science experiments with available equipment. One such experiment focused on the motion of air bubbles in a rectangular container nearly filled with de-ionized water. Bubbles were introduced by shaking and then the container was secured in place for several hours while motion of the bubbles was recorded using time-lapse photography. This paper shows correlation between bubble motion and quasi-steady acceleration levels during one such experiment operation. The quasi-steady acceleration vectors were measured by the Microgravity Acceleration Measurement System (MAMS). Essentially linear motion was observed in the condition considered here. Dr. Pettit also created other conditions which produced linear and circulating motion, which are the subjects of further study. Initial observations of this bubble motion agree with calculations from many microgravity physical science experiments conducted on shuttle microgravity science missions. Many crystal-growth furnaces involve heavy metals and high temperatures in which undesired acceleration-driven convection during solidification can adversely affect the crystal. Presented in this paper will be results showing correlation between bubble motion and the quasi-steady acceleration vector.
17. Motion of Air Bubbles in Water Subjected to Microgravity Accelerations
NASA Technical Reports Server (NTRS)
DeLombard, Richard; Kelly, Eric M.; Hrovar, Kenneth; Nelson, Emily S.; Pettit, Donald R.
2004-01-01
The International Space Station (ISS) serves as a platform for microgravity research for the foreseeable future. A microgravity environment is one in which the effects of gravity are drastically reduced which then allows physical experiments to be conducted without the overpowering effects of gravity. During his six month stay on the ISS, astronaut Donald R Pettit performed many informal/impromptu science experiments with available equipment. One such experiment focused on the motion of air bubbles in a rectangular container nearly filled with de-ionized water. Bubbles were introduced by shaking and the container was secured in place for several hours while motion of the bubbles were recorded using time-lapse photography. This paper shows correlation between bubble motion and quasi-steady acceleration levels during one such experiment operation. The quasi-steady acceleration vectors were measured by the Microgravity Acceleration Measurement System. Essentially linear motion was observed in the condition considered here. Dr. Pettit also created other conditions which produced linear and circulating motion, which are the subjects of further study. Initial observations of this bubble motion agree with calculations from many microgravity physical science experiments conducted on Shuttle microgravity science missions. Many crystal-growth furnaces involve heavy metals and high temperatures in which undesired acceleration-driven convection during solidification can adversely affect the crystal. Presented in this paper will be results showing correlation between bubble motion and the quasi-steady acceleration vector.
18. Effect of combined recompression and air, oxygen, or heliox breathing on air bubbles in rat tissues.
PubMed
Hyldegaard, O; Kerem, D; Melamed, Y
2001-05-01
The fate of bubbles formed in tissues during the ascent from a real or simulated air dive and subjected to therapeutic recompression has only been indirectly inferred from theoretical modeling and clinical observations. We visually followed the resolution of micro air bubbles injected into adipose tissue, spinal white matter, muscle, and tendon of anesthetized rats recompressed to and held at 284 kPa while rats breathed air, oxygen, heliox 80:20, or heliox 50:50. The rats underwent a prolonged hyperbaric air exposure before bubble injection and recompression. In all tissues, bubbles disappeared faster during breathing of oxygen or heliox mixtures than during air breathing. In some of the experiments, oxygen breathing caused a transient growth of the bubbles. In spinal white matter, heliox 50:50 or oxygen breathing resulted in significantly faster bubble resolution than did heliox 80:20 breathing. In conclusion, air bubbles in lipid and aqueous tissues shrink and disappear faster during recompression during breathing of heliox mixtures or oxygen compared with air breathing. The clinical implication of these findings might be that heliox 50:50 is the mixture of choice for the treatment of decompression sickness. PMID:11299250
19. Air bubble-shock wave interaction adjacent to gelantine surface
Lush, P. A.; Tomita, Y.; Onodera, O.; Takayama, K.; Sanada, N.; Kuwahara, M.; Ioritani, N.; Kitayama, O.
1990-07-01
The interaction between a shock wave and an air bubble-adjacent to a gelatine surface is investigated in order to simulate human tissue damage resulting from extracorporeal shock wave lithotripsy. Using high speed cine photography it is found that a shock wave of strength 11 MPa causes 1-3 mm diameter bubbles to produce high velocity microjets with penetration rates of approximately 110 m/s and penetration depths approximately equal to twice the initial bubble diameter. Theoretical considerations for liquid impact on soft solid of similar density indicate that microjet velocities will be twice the penetration rate, i.e. 220 m/s in the present case. Such events are the probable cause of observed renal tissue damage.
20. Kinetics of conversion of air bubbles to air hydrate crystals in antarctic ice.
PubMed
Price, P B
1995-03-24
The depth dependence of bubble concentration at pressures above the transition to the air hydrate phase and the optical scattering length due to bubbles in deep ice at the South Pole are modeled with diffusion-growth data from the laboratory, taking into account the dependence of age and temperature on depth in the ice. The model fits the available data on bubbles in cores from Vostok and Byrd and on scattering length in deep ice at the South Pole. It explains why bubbles and air hydrate crystals coexist in deep ice over a range of depths as great as 800 meters and predicts that at depths below approximately 1400 meters the AMANDA neutrino observatory at the South Pole will operate unimpaired by light scattering from bubbles. PMID:17775808
1. Acoustic wave propagation in air-bubble curtains in water. Part 1. History and theory
SciTech Connect
Domenico, S.N.
1982-03-01
Air bubbles in water increase the compressibility several orders of magnitude above that in bubble-free water, thereby greatly reducing the velocity and increasing attenuation of acoustic waves. Currently, air bubble curtains are used to prevent damage of submerged structures (e.g., dams) by shock waves from submarine explosives. Also, air-bubble curtains are used to reduce damage to water-filler tanks in which metals are formed by explosives. Published results of laboratory experiments confirm theoretic velocity and attenuation functions and demonstrate that these quantities are dependent principally upon frequency, bubble size, and fractional volume of air. 31 references.
2. Bubble stimulation efficiency of dinoflagellate bioluminescence.
PubMed
Deane, Grant B; Stokes, M Dale; Latz, Michael I
2016-02-01
Dinoflagellate bioluminescence, a common source of bioluminescence in coastal waters, is stimulated by flow agitation. Although bubbles are anecdotally known to be stimulatory, the process has never been experimentally investigated. This study quantified the flash response of the bioluminescent dinoflagellate Lingulodinium polyedrum to stimulation by bubbles rising through still seawater. Cells were stimulated by isolated bubbles of 0.3-3 mm radii rising at their terminal velocity, and also by bubble clouds containing bubbles of 0.06-10 mm radii for different air flow rates. Stimulation efficiency, the proportion of cells producing a flash within the volume of water swept out by a rising bubble, decreased with decreasing bubble radius for radii less than approximately 1 mm. Bubbles smaller than a critical radius in the range 0.275-0.325 mm did not stimulate a flash response. The fraction of cells stimulated by bubble clouds was proportional to the volume of air in the bubble cloud, with lower stimulation levels observed for clouds with smaller bubbles. An empirical model for bubble cloud stimulation based on the isolated bubble observations successfully reproduced the observed stimulation by bubble clouds for low air flow rates. High air flow rates stimulated more light emission than expected, presumably because of additional fluid shear stress associated with collective buoyancy effects generated by the high air fraction bubble cloud. These results are relevant to bioluminescence stimulation by bubbles in two-phase flows, such as in ship wakes, breaking waves, and sparged bioreactors. PMID:26061152
3. Effect of compressibility on the rise velocity of an air bubble in porous media
Cihan, Abdullah; Corapcioglu, M. Yavuz
2008-04-01
The objective of this study is to develop a theoretical model to analyze the effect of air compressibility on air bubble migration in porous media. The model is obtained by combining the Newton's second law of motion and the ideal gas law assuming that the air phase in the bubble behaves as an ideal gas. Numerical and analytical solutions are presented for various cases of interest. The model results compare favorably with both experimental data and analytical solutions reported in the literature obtained for an incompressible air bubble migration. The results show that travel velocity of a compressible air bubble in porous media strongly depends on the depth of air phase injection. A bubble released from greater depths travels with a slower velocity than a bubble with an equal volume injected at shallower depths. As an air bubble rises up, it expands with decreasing bubble pressure with depth. The volume of a bubble injected at a 1-m depth increases 10% as the bubble reaches the water table. However, bubble volume increases almost twofold when it reaches to the surface from a depth of 10 m. The vertical rise velocity of a compressible bubble approaches that of an incompressible one regardless of the injection depth and volume as it reaches the water table. The compressible bubble velocity does not exceed 18.8 cm/s regardless of the injection depth and bubble volume. The results demonstrate that the effect of air compressibility on the motion of a bubble cannot be neglected except when the air is injected at very shallow depths.
4. Memory encoding vibrations in a disconnecting air bubble
Zhang, Wendy
2009-03-01
The implosion that disconnects a submerged air bubble into several bubbles provides a simple example of energy focusing. The most efficient disconnection is an entirely symmetric one terminating in a finite-time singularity. At the final moment, the potential energy at the start of the disconnection is entirely condensed into the kinetic energy of a vanishingly small amount of liquid rushing inwards to disconnect the bubble. In reality, however, the initial shape always possesses slight imperfections. We show that a memory of the imperfection remains and controls the final fate of the focusing. Linear stability reveals that even an infinitesimal perturbation is remembered. A slight initial asymmetry excites vibrations in the cross-section shape of the bubble neck. The vibrations persist over time. Near the singularity, their amplitudes freeze, locking onto constant values, while their frequencies chirp, increasing more and more rapidly. The net effect is that the singularity remembers exactly half of the information about the initial imperfection, the half encoded by the vibration amplitudes. We check this scenario in an experiment by releasing an air bubble from a nozzle with an oblong cross-section. This excites an elongation-compression vibrational mode. We measure the vibration excited and find quantitative agreement with linear stability. When the initial distortion has a small, but finite, size, the saturation of the vibration amplitude causes the symmetric singularity to be pre-empted by an asymmetric contact between two distant points on the interface. Numerics reveal that the contact is typically smooth, corresponding to two inward-curving portions of the bubble surface colliding at finite speed. Both the contact speed and curvature vary non-monotonically with the initial distortion size, with abrupt jumps at specific values. This is because the vibration causes contact to occur at different values of the phase. A contact produced when the shape distortion
5. Shockwave and cavitation bubble dynamics of atmospheric air
Leela, Ch.; Bagchi, S.; Tewari, Surya P.; Kiran, P. Prem
2013-11-01
The generation and evolution of laser induced shock waves (SWs) and the hot core plasma (HCP) created by focusing 7 ns, 532 nm laser pulses in ambient air is studied using time resolved shadowgraphic imaging technique. The dynamics of rapidly expanding plasma releasing SWs into the ambient atmosphere were studied for time delays ranging from nanoseconds to milliseconds with ns temporal resolution. The SW is observed to get detached from expanding HCP at around 3μs. Though the SWs were found to expand spherically following the Sedov-Taylor theory, the rapidly expanding HCP shows asymmetric expansion during both the expansion and cooling phase similar to that of inertial cavitation bubble (CB) dynamics. The asymmetric expansion of HCP leads to oscillation of the plasma boundary, eventually leading to collapse by forming vortices formed by the interaction of ambient air.
6. Ceramic membrane defouling (cleaning) by air Nano Bubbles.
PubMed
Ghadimkhani, Aliasghar; Zhang, Wen; Marhaba, Taha
2016-03-01
Ceramic membranes are among the most promising technologies for membrane applications, owing to their excellent resistance to mechanical, chemical, and thermal stresses. However, membrane fouling is still an issue that hampers the applications at large scales. Air Nano Bubbles (NBs), due to high mass transfer efficiency, could potentially prevent fouling of ceramic membrane filtration processes. In this study, bench and pilot scale ceramic membrane filtration was performed with air NBs to resist fouling. To simulate fouling, humic acid, as an organic foulant, was applied to the membrane flat sheet surface. Complete membrane clogging was achieved in less than 6 h. Membrane defouling (cleaning) was performed by directly feeding of air NBs to the membrane cells. The surface of the ceramic membrane was superbly cleaned by air NBs, as revealed by atomic force microscope (AFM) images before and after the treatment. The permeate flux recovered to its initial level (e.g., 26.7 × 10(-9) m(3)/m(2)/s at applied pressure of 275.8 kPa), which indicated that NBs successfully unclogged the pores of the membrane. The integrated ceramic membrane and air NBs system holds potential as an innovative sustainable technology. PMID:26741542
NASA Technical Reports Server (NTRS)
Kelley, H. J.; Lefton, L.
1977-01-01
A chase in a horizontal plane between a pursuer with a large capture radius and a more maneuverable evading vehicle is examined with constant-speed vehicle models. An approximation to the 'sidestepping' maneuver of the Homicidal Chauffeur Game is modified to account for the effect of evader turning rate, and an estimate of capture radius required is so obtained which agrees remarkably well with Cockayne's point-capture result. The maneuver assumes central importance for barrier surfaces appearing in the Game of Two Cars. Results are given for required weapon capture-radius in terms of the maneuverability of the two vehicles. Some calculations of capture radius are presented.
8. Bubbles
Prosperetti, Andrea
2004-06-01
Vanitas vanitatum et omnia vanitas: bubbles are emptiness, non-liquid, a tiny cloud shielding a mathematical singularity. Born from chance, a violent and brief life ending in the union with the (nearly) infinite. But a wealth of phenomena spring forth from this nothingness: underwater noise, sonoluminescence, boiling, and many others. Some recent results on a "blinking bubble" micropump and vapor bubbles in sound fields are outlined. The last section describes Leonardo da Vinci's observation of the non-rectlinear ascent of buoyant bubbles and justifies the name Leonardo's paradox recently attributed to this phenomenon.
9. The influence of clean air entrainment on the droplet effective radius of warm maritime convective clouds
SciTech Connect
Pontikis, C.A.; Hicks, E.M.
1993-09-01
The influence of clear air entrainment on the droplet effective radius of cloudy air parcels is investigated theoretically and experimentally by using data collected in 16 warm maritime tropical cumuli during the Joint Hawaii Warm Rain Project (1985). The theoretical study consists of calculations of the droplet spectrum, droplet effective radius, and liquid water content performed by an entraining cloud parcel model for different entrainment-mixing scenarios. The numerical simulation results are interpreted by means of an analytic equation of the droplet effective radius expressed as a function of both the liquid water content and the droplet concentration. In the experiment study, the behavior of the effective radius is examined at all scales as a function of the liquid water content, used as a dilution degree indicator. At a given cloud level, in the abscence of secondary droplet activation, the effective radius of the droplet spectrum of small-scale parcels (10-Hz data) is roughly independent of the liquid water content and appears unaffected by entrainment. In contrast, if secondary droplet activation occurs in diluted ascending cloud parcels, a wide range of effective radius values is observed for a given liquid water content as a result of the induced variation of the droplet concentration. Further, mean cloud pass effective radii increase with increasing mean pass liquid water contents and mean pass height above cloud base. The results limit the validity of the classical cloud effective radius parameterizations used in the radiative transfer calculations in climate models and some suggestions to improve these parameterizations are presented.
10. Simple method for high-performance stretchable composite conductors with entrapped air bubbles.
PubMed
Hwang, Hyejin; Kim, Dae-Gon; Jang, Nam-Su; Kong, Jeong-Ho; Kim, Jong-Man
2016-12-01
We integrate air bubbles into conductive elastic composite-based stretchable conductors to make them mechanically less stiff and electrically more robust against physical deformations. A surfactant facilitates both the formation and maintenance of air bubbles inside the elastic composites, leading to a simple fabrication of bubble-entrapped stretchable conductors. Based on the unique bubble-entrapped architecture, the elastic properties are greatly enhanced and the resistance change in response to tensile strains can clearly be controlled. The bubble-entrapped conductor achieves ~80 % elongation at ~3.4 times lower stress and ~44.8 % smaller change in the electrical resistance at 80 % tensile strain, compared to bare conductor without air bubbles. PMID:26754940
11. Studies on the tempo of bubble formation in recently cavitated vessels: a model to predict the pressure of air bubbles.
PubMed
Wang, Yujie; Pan, Ruihua; Tyree, Melvin T
2015-06-01
A cavitation event in a vessel replaces water with a mixture of water vapor and air. A quantitative theory is presented to argue that the tempo of filling of vessels with air has two phases: a fast process that extracts air from stem tissue adjacent to the cavitated vessels (less than 10 s) and a slow phase that extracts air from the atmosphere outside the stem (more than 10 h). A model was designed to estimate how water tension (T) near recently cavitated vessels causes bubbles in embolized vessels to expand or contract as T increases or decreases, respectively. The model also predicts that the hydraulic conductivity of a stem will increase as bubbles collapse. The pressure of air bubbles trapped in vessels of a stem can be predicted from the model based on fitting curves of hydraulic conductivity versus T. The model was validated using data from six stem segments each of Acer mono and the clonal hybrid Populus 84 K (Populus alba × Populus glandulosa). The model was fitted to results with root mean square error less than 3%. The model provided new insight into the study of embolism formation in stem tissue and helped quantify the bubble pressure immediately after the fast process referred to above. PMID:25907963
12. Probing the interaction between air bubble and sphalerite mineral surface using atomic force microscope.
PubMed
Xie, Lei; Shi, Chen; Wang, Jingyi; Huang, Jun; Lu, Qiuyi; Liu, Qingxia; Zeng, Hongbo
2015-03-01
The interaction between air bubbles and solid surfaces plays important roles in many engineering processes, such as mineral froth flotation. In this work, an atomic force microscope (AFM) bubble probe technique was employed, for the first time, to directly measure the interaction forces between an air bubble and sphalerite mineral surfaces of different hydrophobicity (i.e., sphalerite before/after conditioning treatment) under various hydrodynamic conditions. The direct force measurements demonstrate the critical role of the hydrodynamic force and surface forces in bubble-mineral interaction and attachment, which agree well with the theoretical calculations based on Reynolds lubrication theory and augmented Young-Laplace equation by including the effect of disjoining pressure. The hydrophobic disjoining pressure was found to be stronger for the bubble-water-conditioned sphalerite interaction with a larger hydrophobic decay length, which enables the bubble attachment on conditioned sphalerite at relatively higher bubble approaching velocities than that of unconditioned sphalerite. Increasing the salt concentration (i.e., NaCl, CaCl2) leads to weakened electrical double layer force and thereby facilitates the bubble-mineral attachment, which follows the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory by including the effects of hydrophobic interaction. The results provide insights into the basic understanding of the interaction mechanism between bubbles and minerals at nanoscale in froth flotation processes, and the methodology on probing the interaction forces of air bubble and sphalerite surfaces in this work can be extended to many other mineral and particle systems. PMID:25675101
13. A study of the accuracy of neutrally buoyant bubbles used as flow tracers in air
NASA Technical Reports Server (NTRS)
Kerho, Michael F.
1993-01-01
Research has been performed to determine the accuracy of neutrally buoyant and near neutrally buoyant bubbles used as flow tracers in air. Theoretical, computational, and experimental results are presented to evaluate the dynamics of bubble trajectories and factors affecting their ability to trace flow-field streamlines. The equation of motion for a single bubble was obtained and evaluated using a computational scheme to determine the factors which affect a bubble's trajectory. A two-dimensional experiment was also conducted to experimentally determine bubble trajectories in the stagnation region of NACA 0012 airfoil at 0 deg angle of attack using a commercially available helium bubble generation system. Physical properties of the experimental bubble trajectories were estimated using the computational scheme. These properties included the density ratio and diameter of the individual bubbles. the helium bubble system was then used to visualize and document the flow field about a 30 deg swept semispan wing with simulated glaze ice. Results were compared to Navier-Stokes calculations and surface oil flow visualization. The theoretical and computational analysis have shown that neutrally buoyant bubbles will trace even the most complex flow patterns. Experimental analysis revealed that the use of bubbles to trace flow patterns should be limited to qualitative measurements unless care is taken to ensure neutral buoyancy. This is due to the difficulty in the production of neutrally buoyant bubbles.
14. The impact and bounce of air bubbles at a flat fluid interface.
PubMed
Manica, Rogerio; Klaseboer, Evert; Chan, Derek Y C
2016-04-01
The rise and impact of bubbles at an initially flat but deformable liquid-air interface in ultraclean liquid systems are modelled by taking into account the buoyancy force, hydrodynamic drag, inertial added mass effect and drainage of the thin film between the bubble and the interface. The bubble-surface interaction is analyzed using lubrication theory that allows for both bubble and surface deformation under a balance of normal stresses and surface tension as well as the long-range nature of deformation along the interface. The quantitative result for collision and bounce is sensitive to the impact velocity of the rising bubble. This velocity is controlled by the combined effects of interfacial tension via the Young-Laplace equation and hydrodynamic stress on the surface, which determine the deformation of the bubble. The drag force that arises from the hydrodynamic stress in turn depends on the hydrodynamic boundary conditions on the bubble surface and its shape. These interrelated factors are accounted for in a consistent manner. The model can predict the rise velocity and shape of millimeter-size bubbles in ultra-clean water, in two silicone oils of different densities and viscosities and in ethanol without any adjustable parameters. The collision and bounce of such bubbles with a flat water/air, silicone oil/air and ethanol/air interface can then be predicted with excellent agreement when compared to experimental observations. PMID:26924623
15. Exploring morphological variations of a laser-induced water jet in temporal evolution: formation of an air bubble enclosing a water drop
Chen, Ross C. C.; Yu, Y. T.; Su, K. W.; Chen, Y. F.
2013-11-01
We explore the spatio-temporal dynamics of a water jet that is generated by laser-induced water breakdown beneath a flat free surface. We find that morphological variations in the temporal evolution can be divided into three categories depending on the depth parameter γ, which is the ratio of the water-breakdown depth to the maximum bubble radius. For a depth parameter in the range 0.8 ≤ γ ≤ 1.03, we observe an intriguing pattern formation in which an air bubble perfectly encloses a water drop through the process of the Plateau-Rayleigh instability.
16. Passive Underwater Noise Attenuation Using Large Encapsulated Air Bubbles.
PubMed
Lee, Kevin M; Wochner, Mark S; Wilson, Preston S
2016-01-01
Measurements demonstrating low-frequency underwater sound attenuation using arrays of large, tethered, stationary encapsulated bubbles to surround a sound source were compared with various effective medium models for the acoustic dispersion relationship in bubbly liquids. Good agreement was observed between measurements for the large bubbles (on the order of 10 cm) at frequencies below 1 kHz and a model originally intended to describe the acoustic behavior of ultrasound contrast agents. The primary goal is to use the model for designing encapsulated-bubble-based underwater noise abatement systems and to reduce uncertainty in system performance. PMID:26611010
17. Electrical breakdown of transformer oil with sulfur hexafluoride and air bubbles
Gadzhiev, M. Kh.; Isakaev, E. Kh.; Tyuftyaev, A. S.; Akimov, P. L.; Yusupov, D. I.; Kulikov, Yu. M.; Panov, V. A.
2015-07-01
The influence of gas bubbles on the breakdown voltage of transformer oil is experimentally studied. The influence of the oil flow on the electrical characteristics of breakdown is analyzed. It is shown that sulfur hexafluoride and air bubbles decrease the breakdown voltage.
18. Detection and 3D representation of pulmonary air bubbles in HRCT volumes
Silva, Jose S.; Silva, Augusto F.; Santos, Beatriz S.; Madeira, Joaquim
2003-05-01
Bubble emphysema is a disease characterized by the presence of air bubbles within the lungs. With the purpose of identifying pulmonary air bubbles, two alternative methods were developed, using High Resolution Computer Tomography (HRCT) exams. The search volume is confined to the pulmonary volume through a previously developed pulmonary contour detection algorithm. The first detection method follows a slice by slice approach and uses selection criteria based on the Hounsfield levels, dimensions, shape and localization of the bubbles. Candidate regions that do not exhibit axial coherence along at least two sections are excluded. Intermediate sections are interpolated for a more realistic representation of lungs and bubbles. The second detection method, after the pulmonary volume delimitation, follows a fully 3D approach. A global threshold is applied to the entire lung volume returning candidate regions. 3D morphologic operators are used to remove spurious structures and to circumscribe the bubbles. Bubble representation is accomplished by two alternative methods. The first generates bubble surfaces based on the voxel volumes previously detected; the second method assumes that bubbles are approximately spherical. In order to obtain better 3D representations, fits super-quadrics to bubble volume. The fitting process is based on non-linear least squares optimization method, where a super-quadric is adapted to a regular grid of points defined on each bubble. All methods were applied to real and semi-synthetical data where artificial and randomly deformed bubbles were embedded in the interior of healthy lungs. Quantitative results regarding bubble geometric features are either similar to a priori known values used in simulation tests, or indicate clinically acceptable dimensions and locations when dealing with real data.
19. Gas and liquid measurements in air-water bubbly flows
SciTech Connect
Zhou, X.; Doup, B.; Sun, X.
2012-07-01
Local measurements of gas- and liquid-phase flow parameters are conducted in an air-water two-phase flow loop. The test section is a vertical pipe with an inner diameter of 50 mm and a height of 3.2 m. The measurements are performed at z/D = 10. The gas-phase measurements are performed using a four-sensor conductivity probe. The data taken from this probe are processed using a signal processing program to yield radial profiles of the void fraction, bubble velocity, and interfacial area concentration. The velocity measurements of the liquid-phase are performed using a state-of-the-art Particle Image Velocimetry (PIV) system. The raw PIV images are acquired using fluorescent particles and an optical filtration device. Image processing is used to remove noise in the raw PIV images. The statistical cross correlation is introduced to determine the axial velocity field and turbulence intensity of the liquid-phase. Measurements are currently being performed at z/D = 32 to provide a more complete data set. These data can be used for computational fluid dynamic model development and validation. (authors)
20. Surfactants as bubble surface modifiers in the flotation of algae: dissolved air flotation that utilizes a chemically modified bubble surface.
PubMed
Henderson, Rita K; Parsons, Simon A; Jefferson, Bruce
2008-07-01
In this paper we present an investigation into the use of bubbles modified with surfactants in dissolved air flotation (DAF). Bubble modification was investigated by dosing surfactants of varying character into the saturator of a DAF unit in turn. The cell removal efficiency only improved when using a cationic surfactant where optimum removal of Microcystis aeruginosa cells was obtained when using 0.0022-0.004 mequiv L(-1) surfactant. However, the magnitude of the removal differed according to the hydrophobicity of the surfactant. Typically, the more efficiently the surfactant adsorbed at the bubble interface, the better the removal efficiency. When the dose to saturator ratio was kept constant and the recycle ratio varied, the removal efficiency improved with increasing recycle ratio, reaching a maximum removal efficiency of 87% for M. aeruginosa. This value was comparable with that predicted by a theoretical model. The bubble collection efficiency of a maximum of two cells per bubble was constant irrespective of the influent cell number or recycle ratio. Treatment of additional species in this way revealed a relationship between increasing size and both increasing removal efficiency and decreasing surfactant dose, which is supported by theoretical relationships. PMID:18678021
1. The wake structures of the air bubbles rising in a Hele-Shaw cell
Moskun, Eric; Wu, Mingming; Zarandi, Mehrdad M.
1997-11-01
The wake structures of the penny-shaped air bubbles rising in a layer of fluid contained in a Hele-Shaw cell were studied qualitatively by colored dye visualization technique, and quantitatively by digital particle imaging velocimetry(DPIV). We found that the straight path of a rising circular bubble was changed to a zigzag path when the Reynolds number R (proportional to the bubble terminal velocity) exceeded a threshold R_c.( Erin Kelley and Mingming Wu, Phys. Rev. Lett.), 79, 1265(1997). The colored dye visualization results demonstrated that the path instability was a consequence of vortex shedding behind the bubbles. The DPIV measurements supplied the full velocity fields behind the bubbles, and revealed the details of the vortex forming processes. The boundary conditions at the surfaces of the small bubbles will be discussed.
2. Role of air bubbles overlooked in the adsorption of perfluorooctanesulfonate on hydrophobic carbonaceous adsorbents.
PubMed
Meng, Pingping; Deng, Shubo; Lu, Xinyu; Du, Ziwen; Wang, Bin; Huang, Jun; Wang, Yujue; Yu, Gang; Xing, Baoshan
2014-12-01
Hydrophobic interaction has been considered to be responsible for adsorption of perfluorooctanesulfonate (PFOS) on the surface of hydrophobic adsorbents, but the long C-F chain in PFOS is not only hydrophobic but also oleophobic. In this study, for the first time we propose that air bubbles on the surface of hydrophobic carbonaceous adsorbents play an important role in the adsorption of PFOS. The level of adsorption of PFOS on carbon nanotubes (CNTs), graphite (GI), graphene (GE), and powdered activated carbon (PAC) decreases after vacuum degassing. Vacuum degassing time and pressure significantly affect the removal of PFOS by these adsorbents. After vacuum degassing at 0.01 atm for 36 h, the extent of removal of PFOS by the pristine CNTs and GI decreases 79% and 74%, respectively, indicating the main contribution of air bubbles to PFOS adsorption. When the degassed solution is recontacted with air during the adsorption process, the removal of PFOS recovers to the value obtained without vacuum degassing, further verifying the key role of air bubbles in PFOS adsorption. By theoretical calculation, the distribution of PFOS in air bubbles on the adsorbent surfaces is discussed, and a new schematic sorption model of PFOS on carbonaceous adsorbents in the presence of air bubbles is proposed. The accumulation of PFOS at the interface of air bubbles on the adsorbents is primarily responsible for its adsorption, providing a new mechanistic insight into the transport, fate, and removal of PFOS. PMID:25365738
3. Effect of heliox, oxygen and air breathing on helium bubbles after heliox diving.
PubMed
Hyldegaard, O; Jensen, T
2007-01-01
In helium saturated rat abdominal adipose tissue, helium bubbles were studied at 101.3 kPa during breathing of either heliox(80:20), 100% oxygen or air after decompression from an exposure to heliox at 405 kPa for one hour. While breathing heliox bubbles initially grew for 15-115 minutes then shrank slowly; three out of 10 bubbles disappeared in the observation period. During oxygen breathing all bubbles initially grew for 10-80 minutes then shrank until they disappeared from view; in the growing phase, oxygen caused faster growth than heliox breathing, but bubbles disappeared sooner with oxygen breathing than with heliox or air breathing. In the shrinking phase, shrinkage is faster with heliox and oxygen breathing than with air breathing. Air breathing caused consistent growth of all bubbles. With heliox and oxygen breathing, most animals survived during the observation period but with air breathing, most animals died of decompression sickness regardless of whether the surrounding atmosphere was helium or air. If recompression beyond the maximum treatment pressure of oxygen is required, these results indicate that a breathing mixture of heliox may be better than air during the treatment of decompression sickness following heliox diving. PMID:17520862
4. Presence and absence of a water film between moving air bubbles and a plate
Remenyik, Carl J.
1990-01-01
The thickness of water films between an inclined Lucite plate submerged in water and air bubbles moving beneath it was measured with a small impedance probe. The instrument was calibrated with a laser interferometer built for this purpose. The bubbles released beneath the plate varied in size from 10 cc to 100 cc. At a plate inclination angle of 0.98°, and in tap water, an uninterrupted water film covered most of the bubbles. Some bubbles, however, dewetted the plate, and the water film covered only a forward part of the bubble. When the film was uninterrupted, its thickness was very uniform from front to rear. When the bubble dewetted the plate, a large forward section of the film had the same uniform thickness, but this was followed by a hump on the film the rear slope of which ended at the plate surface. For some of the experiments, the surface tension of the water was reduced by admixing a detergent. In these experiments, dewetting was not observed. In a second set of experiments, a hand held transparent container filled with water and a 1.3 cm3 air bubble was used to observe visually the behavior of the moving bubble and its associated water film.
5. Electric Field Effects on an Injected Air Bubble at Detachment in a Low Gravity Environment
NASA Technical Reports Server (NTRS)
Iacona, Estelle; Herman, Cila; Chang, Shinan
2002-01-01
The objective of the study is to investigate the behavior of individual air bubbles injected through an orifice into an electrically insulating liquid under the influence of a static and uniform electric field. Bubble formation and detachment were visualized and recorded in microgravity using a high-speed video camera. Bubble volume, dimensions and contact angle at detachment were measured. In addition to the experimental studies, a simple model, predicting bubble characteristics at detachment was developed. The model, based on thermodynamic considerations, accounts for the level of gravity as well as the magnitude of the uniform electric field. Measured data and model predictions show good agreement, and indicate that the level of gravity and the electric field magnitude significantly affect bubble shape, volume and dimensions.
6. Noise reduction by the application of an air-bubble curtain in offshore pile driving
Tsouvalas, A.; Metrikine, A. V.
2016-06-01
Underwater noise pollution is a by-product of marine industrial operations. In particular, the noise generated when a foundation pile is driven into the soil with an impact hammer is considered to be harmful for the aquatic species. In an attempt to reduce the ecological footprint, several noise mitigation techniques have been investigated. Among the various solutions proposed, the air-bubble curtain is often applied due to its efficacy in noise reduction. In this paper, a model is proposed for the investigation of the sound reduction during marine piling when an air-bubble curtain is placed around the pile. The model consists of the pile, the surrounding water and soil media, and the air-bubble curtain which is positioned at a certain distance from the pile surface. The solution approach is semi-analytical and is based on the dynamic sub-structuring technique and the modal decomposition method. Two main results of the paper can be distinguished. First, a new model is proposed that can be used for predictions of the noise levels in a computationally efficient manner. Second, an analysis is presented of the principal mechanisms that are responsible for the noise reduction due to the application of the air-bubble curtain in marine piling. The understanding of these mechanisms turns to be crucial for the exploitation of the maximum efficiency of the system. It is shown that the principal mechanism of noise reduction depends strongly on the frequency content of the radiated sound and the characteristics of the bubbly medium. For piles of large diameter which radiate most of the acoustic energy at relatively low frequencies, the noise reduction is mainly attributed to the mismatch of the acoustic impedances between the seawater and the bubbly layer. On the contrary, for smaller piles and when the radiated acoustic energy is concentrated at frequencies close to, or higher than, the resonance frequency of the air bubbles, the sound absorption within the bubbly layer
7. Growth of oxygen bubbles during recharge process in zinc-air battery
Wang, Keliang; Pei, Pucheng; Ma, Ze; Chen, Huicui; Xu, Huachi; Chen, Dongfang; Xing, Haoqiang
2015-11-01
Rechargeable zinc-air battery used for energy storage has a serious problem of charging capacity limited by oxygen bubble coalescence. Fast removal of oxygen bubbles adhered to the charging electrode surface is of great importance for improving the charging performance of the battery. Here we show that the law of oxygen bubble growth can be achieved by means of phase-field simulation, revealing two phenomena of bubble detachment and bubble coalescence located in the charging electrode on both sides. Hydrodynamic electrolyte and partial insulation structure of the charging electrode are investigated to solve the problem of oxygen bubble coalescence during charging. Two types of rechargeable zinc-air battery are developed on the basis of different tri-electrode configurations, demonstrating that the charging performance of the battery with electrolyte flow (Ⅰ) is better than that of the battery with the partially insulated electrode (Ⅱ), while the battery Ⅱ is superior to the battery Ⅰ in the discharging performance, cost and portability. The proposed solutions and results would be available for promoting commercial application of rechargeable zinc-air batteries or other metal-air batteries.
8. Hydrophilic strips for preventing air bubble formation in a microfluidic chamber.
PubMed
Choi, Munseok; Na, Yang; Kim, Sung-Jin
2015-12-01
In a microfluidic chamber, unwanted formation of air bubbles is a critical problem. Here, we present a hydrophilic strip array that prevents air bubble formation in a microfluidic chamber. The array is located on the top surface of the chamber, which has a large variation in width, and consists of a repeated arrangement of super- and moderately hydrophilic strips. This repeated arrangement allows a flat meniscus (i.e. liquid front) to form when various solutions consisting of a single stream or two parallel streams with different hydrophilicities move through the chamber. The flat meniscus produced by the array completely prevents the formation of bubbles. Without the array in the chamber, the meniscus shape is highly convex, and bubbles frequently form in the chamber. This hydrophilic strip array will facilitate the use of a microfluidic chamber with a large variation in width for various microfluidic applications. PMID:26382942
9. Interaction between bubble and air-backed plate with circular hole
Liu, Y. L.; Wang, S. P.; Zhang, A. M.
2016-06-01
This paper investigates the nonlinear interaction between a violent bubble and an air-backed plate with a circular hole. A numerical model is established using the incompressible potential theory coupled with the boundary integral method. A double-node technique is used to solve the overdetermined problem caused by the intersection between the solid wall and the free surface. A spark-generated bubble near the air-backed plate with a circular hole is observed experimentally using a high-speed camera. Our numerical results agree well with the experimental results. Both experimental and numerical results show that a multilevel spike emerges during the bubble's expansion and contraction. Careful numerical simulation reveals that this special type of spike is caused by the discontinuity in the boundary condition. The influences of the hole size and depth on the bubble and spike dynamics are also analyzed.
10. Solution-Processed Ultraelastic and Strong Air-Bubbled Graphene Foams.
PubMed
Lv, Lingxiao; Zhang, Panpan; Cheng, Huhu; Zhao, Yang; Zhang, Zhipan; Shi, Gaoquan; Qu, Liangti
2016-06-01
Solution-processed ultraelastic graphene foams are prepared via a convenient air-bubble-promoted synthesis. These foams can dissipate external compression through the ordered interconnecting graphene network between the bubbles without causing a local fracture and thus reliably show compressive stress of 5.4 MPa at a very high strain of 99%, setting a new benchmark for solution-processed graphene foams. PMID:27171551
11. Effect of air bubble on inflammation after cataract surgery in rabbit eyes
PubMed Central
Demirci, Goktug; Karabaş, Levent; Maral, Hale; Ozdek, Şengül; Gülkılık, Gökhan
2013-01-01
Purpose: Intense inflammation after cataract surgery can cause cystoid macular edema, posterior synechia and posterior capsule opacification. This experimental study was performed to investigate the effect of air bubble on inflammation when given to anterior chamber of rabbit eyes after cataract surgery. Materials and Methods: 30 eyes of 15 rabbits were enrolled in the study. One of the two eyes was in the study group and the other eye was in the control group. After surgery air bubble was given to the anterior chamber of the study group eye and balanced salt solution (BSS; Alcon) was left in the anterior chamber of control eye. Results: On the first, second, fourth and fifth days, anterior chamber inflammations of the eyes were examined by biomicroscopy. On the sixth day anterior chamber fluid samples were taken for evaluation of nitric oxide levels as an inflammation marker. When the two groups were compared, in the air bubble group there was statistically less inflammation was seen. (1, 2, 4. days P = 0,001, and 5. day P = 0,009). Conclusions: These results have shown that when air bubble is left in anterior chamber of rabbits’ eyes after cataract surgery, it reduced inflammation. We believe that, air bubble in the anterior chamber may be more beneficial in the cataract surgery of especially pediatric age group, uveitis patients and diabetics where we see higher inflammation. However, greater and long termed experimental and clinical studies are necessary for more accurate findings. PMID:23571264
12. An experimental study on the effect of air bubble injection on the flow induced rotational hub
SciTech Connect
Nouri, N.M.; Sarreshtehdari, A.
2009-01-15
Modification of shear stress due to air bubbles injection in a rotary device was investigated experimentally. Air bubbles inject to the water flow crosses the neighbor of the hub which can rotate just by water flow shear stresses, in this device. Increasing air void fraction leads to decrease of shear stresses exerted on the hub surface until in high void fractions, the hub motion stopped as observed. Amount of skin friction decrease has been estimated by counting central hub rotations. Wall shear stress was decreased by bubble injection in all range of tested Reynolds number, changing from 50,378 to 71,238, and also by increasing air void fraction from zero to 3.06%. Skin friction reduction more than 85% was achieved in this study as maximum measured volume of air fraction injected to fluid flow while bubbles are distinct and they do not make a gas layer. Significant skin friction reduction obtained in this special case indicate that using small amount of bubble injection causes large amount of skin friction reduction in some rotary parts in the liquid phases like as water. (author)
13. Effects of floc and bubble size on the efficiency of the dissolved air flotation (DAF) process.
PubMed
Han, Mooyoung; Kim, Tschung-il; Kim, Jinho
2007-01-01
Dissolved air flotation (DAF) is a method for removing particles from water using micro bubbles instead of settlement. The process has proved to be successful and, since the 1960s, accepted as an alternative to the conventional sedimentation process for water and wastewater treatment. However, limited research into the process, especially the fundamental characteristics of bubbles and particles, has been carried out. The single collector collision model is not capable of determining the effects of particular characteristics, such as the size and surface charge of bubbles and particles. Han has published a set of modeling results after calculating the collision efficiency between bubbles and particles by trajectory analysis. His major conclusion was that collision efficiency is maximum when the bubbles and particles are nearly the same size but have opposite charge. However, experimental verification of this conclusion has not been carried out yet. This paper describes a new method for measuring the size of particles and bubbles developed using computational image analysis. DAF efficiency is influenced by the effect of the recycle ratio on various average floc sizes. The larger the recycle ratio, the higher the DAF efficiency at the same pressure and particle size. The treatment efficiency is also affected by the saturation pressure, because the bubble size and bubble volume concentration are controlled by the pressure. The highest efficiency is obtained when the floc size is larger than the bubble size. These results, namely that the highest collision efficiency occurs when the particles and bubbles are about the same size, are more in accordance with the trajectory model than with the white water collector model, which implies that the larger the particles, the higher is the collision efficiency. PMID:18048983
14. Three-dimensionally ordered array of air bubbles in a polymer film
NASA Technical Reports Server (NTRS)
Srinivasarao, M.; Collings, D.; Philips, A.; Patel, S.; Brown, C. S. (Principal Investigator)
2001-01-01
We report the formation of a three-dimensionally ordered array of air bubbles of monodisperse pore size in a polymer film through a templating mechanism based on thermocapillary convection. Dilute solutions of a simple, coil-like polymer in a volatile solvent are cast on a glass slide in the presence of moist air flowing across the surface. Evaporative cooling and the generation of an ordered array of breath figures leads to the formation of multilayers of hexagonally packed water droplets that are preserved in the final, solid polymer film as spherical air bubbles. The dimensions of these bubbles can be controlled simply by changing the velocity of the airflow across the surface. When these three-dimensionally ordered macroporous materials have pore dimensions comparable to the wavelength of visible light, they are of interest as photonic band gaps and optical stop-bands.
15. Massively-multicellular alignment with the self-aggregate of air bubbles.
PubMed
Tanaka, Nobuyuki; Haraguchi, Yuji; Shimizu, Tatsuya; Yamato, Masayuki; Okano, Teruo; Miyake, Jun
2015-08-01
This study proposes a cell manipulation method with aggregated air bubbles on cell culture medium. This method requires no additional regents nor devices, except for normal cell-culture materials such as cell culture dishes and pipettes. Bubbles generated by pipetting were spontaneously aggregated with regularity on the whole surface and used as a mask for avoiding cell adhesion after cell-seeding. The diameter of bubbles was able to be controlled by the size of micro-pipette tips. Seeded cells spread to the whole area along the bubble gap. This technique is a surface-tension-driven self-assembly-based method. Using this technique, millions of living cells were successfully aligned into a hexagonal pattern within 300 μm in pattern width on the whole surface of dish for less than 2 h. PMID:26737056
16. Effect of surfactants on the rate of growth of an air bubble by rectified diffusion.
PubMed
Lee, Judy; Kentish, Sandra; Ashokkumar, Muthupandian
2005-08-01
The rectified diffusion growth of a single air bubble levitated in an acoustic field (frequency = 22.35 kHz) in water and in aqueous solutions containing surfactants (sodium dodecyl sulfate and sodium dodecylbenzene sulfonate) was investigated. As reported by Crum (J. Acoust. Soc. Am. 1980, 68, 203), the presence of surfactants at the bubble/liquid interface enhanced the growth rate of the bubble by rectified diffusion. It is suggested in this paper that in addition to the effect of surfactants on the surface tension and interfacial resistance to mass transfer, the effect of surface rheological properties may also contribute to the cause of the enhancement observed in the bubble growth rate. PMID:16852840
17. The influence of bubble plumes on air-seawater gas transfer velocities
Asher, W. E.; Karle, L. M.; Higgins, B. J.; Farley, P. J.; Monahan, E. C.; Leifer, I. S.
1996-05-01
Laboratory results have demonstrated that bubble plumes are a very efficient air-water gas transfer mechanism. Because breaking waves generate bubble plumes, it could be possible to correlate the air-sea gas transport velocity kL with whitecap coverage. This correlation would then allow kL to be predicted from measurements of apparent microwave brightness temperature through the increase in sea surface microwave emissivity associated with breaking waves. In order to develop this remote-sensing-based method for predicting air-sea gas fluxes, a whitecap simulation tank was used to measure evasive and invasive kL values for air-seawater transfer of carbon dioxide, oxygen, helium, sulfur hexafluoride, and dimethyl sulfide at cleaned and surfactant-influenced water surfaces. An empirical model has been developed that can predict kL from bubble plume coverage, diffusivity, and solubility. The observed dependence of kL on molecular diffusivity and aqueous-phase solubility agrees with the predictions of modeling studies of bubble-driven air-water gas transfer. It has also been shown that soluble surfactants can decrease kL even in the presence of breaking waves.
18. Size distribution of oceanic air bubbles entrained in sea-water by wave-breaking
NASA Technical Reports Server (NTRS)
Resch, F.; Avellan, F.
1982-01-01
The size of oceanic air bubbles produced by whitecaps and wave-breaking is determined. The production of liquid aerosols at the sea surface is predicted. These liquid aerosols are at the origin of most of the particulate materials exchanged between the ocean and the atmosphere. A prototype was designed and built using an optical technique based on the principle of light scattering at an angle of ninety degrees from the incident light beam. The output voltage is a direct function of the bubble diameter. Calibration of the probe was carried out within a range of 300 microns to 1.2 mm. Bubbles produced by wave-breaking in a large air-sea interaction simulating facility. Experimental results are given in the form of size spectrum.
19. Bubble-size distributions produced by wall injection of air into flowing freshwater, saltwater and surfactant solutions
Winkel, Eric S.; Ceccio, Steven L.; Dowling, David R.; Perlin, Marc
2004-12-01
As air is injected into a flowing liquid, the resultant bubble characteristics depend on the properties of the injector, near-wall flow, and flowing liquid. Previous research has shown that near-wall bubbles can significantly reduce skin-friction drag. Air was injected into the turbulent boundary layer on a test section wall of a water tunnel containing various concentrations of salt and surfactant (Triton-X-100, Union Carbide). Photographic records show that the mean bubble diameter decreased monotonically with increasing salt and surfactant concentrations. Here, 33 ppt saltwater bubbles had one quarter, and 20 ppm Triton-X-100 bubbles had one half of the mean diameter of freshwater bubbles.
20. Study of interfacial area transport and sensitivity analysis for air-water bubbly flow
SciTech Connect
Kim, S.; Sun, X.; Ishii, M.; Beus, S.G.
2000-09-01
The interfacial area transport equation applicable to the bubbly flow is presented. The model is evaluated against the data acquired by the state-of-the-art miniaturized double-sensor conductivity probe in an adiabatic air-water co-current vertical test loop under atmospheric pressure condition. In general, a good agreement, within the measurement error of plus/minus 10%, is observed for a wide range in the bubbly flow regime. The sensitivity analysis on the individual particle interaction mechanisms demonstrates the active interactions between the bubbles and highlights the mechanisms playing the dominant role in interfacial area transport. The analysis employing the drift flux model is also performed for the data acquired. Under the given flow conditions, the distribution parameter of 1.076 yields the best fit to the data.
1. Tunneling effects in resonant acoustic scattering of an air bubble in unbounded water.
PubMed
Simão, André G; Guimarães, Luiz G
2016-01-01
The problem of acoustic scattering of a gaseous spherical bubble immersed within unbounded liquid surrounding is considered in this work. The theory of partial wave expansion related to this problem is revisited. A physical model based on the analogy between acoustic scattering and potential scattering in quantum mechanics is proposed to describe and interpret the acoustical natural oscillation modes of the bubble, namely, the resonances. In this context, a physical model is devised in order to describe the air water interface and the implications of the high density contrast on the various regimes of the scattering resonances. The main results are presented in terms of resonance lifetime periods and quality factors. The explicit numerical calculations are undertaken through an asymptotic analysis considering typical bubble dimensions and underwater sound wavelengths. It is shown that the resonance periods are scaled according to the Minnaert's period, which is the short lived resonance mode, called breathing mode of the bubble. As expected, resonances with longer lifetimes lead to impressive cavity quality Q-factor ranging from 1010 to 105. The present theoretical findings lead to a better understanding of the energy storage mechanism in a bubbly medium. PMID:27331803
2. Influence of sonication conditions on the efficiency of ultrasonic cleaning with flowing micrometer-sized air bubbles.
PubMed
Tuziuti, Toru
2016-03-01
This paper describes the sizes of cleaned areas under different sonication conditions with the addition of flowing micrometer-sized air bubbles. The differences in the cleaned area of a glass plate pasted with silicon grease as a dirty material under different sonication conditions were investigated after tiny bubbles were blown on the dirty plate placed in an underwater sound field. The ultrasound was applied perpendicular to the bubble flow direction. The shape of the cleaned areas was nearly elliptical, so the lengths of the minor and major axes were measured. The length of the minor axis under sweep conditions (amplitude modulation), for which the average power was lower than that for continuous wave (CW) irradiation, was comparable to that for CW irradiation and was slightly larger than under bubble flow only. Not only the relatively high power for CW irradiation, but also the larger angular change of the bubble flow direction under sweep conditions contributed to the enlargement of the cleaned area in the direction of the minor axis. The combination of bubble flow and sonication under sweep or CW conditions produced a larger cleaned area compared with bubble flow only, although the increase was not higher than 20%. A rapid change from an air to water interface caused by the bubble flow and water jets caused by the collapse of bubbles due to violent pulsation is the main cleaning mechanism under a combination of ultrasound and bubble flow. PMID:26422770
3. Effect of oxygen and heliox breathing on air bubbles in adipose tissue during 25-kPa altitude exposures.
PubMed
Randsøe, T; Kvist, T M; Hyldegaard, O
2008-11-01
At altitude, bubbles are known to form and grow in blood and tissues causing altitude decompression sickness. Previous reports indicate that treatment of decompression sickness by means of oxygen breathing at altitude may cause unwanted bubble growth. In this report we visually followed the in vivo changes of micro air bubbles injected into adipose tissue of anesthetized rats at 101.3 kPa (sea level) after which they were decompressed from 101.3 kPa to and held at 25 kPa (10,350 m), during breathing of oxygen or a heliox(34:66) mixture (34% helium and 66% oxygen). Furthermore, bubbles were studied during oxygen breathing preceded by a 3-h period of preoxygenation to eliminate tissue nitrogen before decompression. During oxygen breathing, bubbles grew from 11 to 198 min (mean: 121 min, +/-SD 53.4) after which they remained stable or began to shrink slowly. During heliox breathing bubbles grew from 30 to 130 min (mean: 67 min, +/-SD 31.0) from which point they stabilized or shrank slowly. No bubbles disappeared during either oxygen or heliox breathing. Preoxygenation followed by continuous oxygen breathing at altitude caused most bubbles to grow from 19 to 179 min (mean: 51 min, +/-SD 47.7) after which they started shrinking or remained stable throughout the observation period. Bubble growth time was significantly longer during oxygen breathing compared with heliox breathing and preoxygenated animals. Significantly more bubbles disappeared in preoxygenated animals compared with oxygen and heliox breathing. Preoxygenation enhanced bubble disappearance compared with oxygen and heliox breathing but did not prevent bubble growth. The results indicate that oxygen breathing at 25 kPa promotes air bubble growth in adipose tissue regardless of the tissue nitrogen pressure. PMID:18756005
4. Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats.
PubMed
Hyldegaard, O; Kerem, D; Melamed, Y
2011-09-01
Deep tissue isobaric counterdiffusion that may cause unwanted bubble formation or transient bubble growth has been referred to in theoretical models and demonstrated by intravascular gas formation in animals, when changing inert breathing gas from nitrogen to helium after hyperbaric air breathing. We visually followed the in vivo resolution of extravascular air bubbles injected at 101 kPa into nitrogen supersaturated rat tissues: adipose, spinal white matter, skeletal muscle or tail tendon. Bubbles were observed during isobaric breathing-gas shifts from air to normoxic (80:20) heliox mixture while at 285 kPa or following immediate recompression to either 285 or 405 kPa, breathing 80:20 and 50:50 heliox mixtures. During the isobaric shifts, some bubbles in adipose tissue grew marginally for 10-30 min, subsequently they shrank and disappeared at a rate similar to or faster than during air breathing. No such bubble growth was observed in spinal white matter, skeletal muscle or tendon. In spinal white matter, an immediate breathing gas shift after the hyperbaric air exposure from air to both (80:20) and (50:50) heliox, coincident with recompression to either 285 or 405 kPa, caused consistent shrinkage of all air bubbles, until they disappeared from view. Deep tissue isobaric counterdiffusion may cause some air bubbles to grow transiently in adipose tissue. The effect is marginal and of no clinical consequence. Bubble disappearance rate is faster with heliox breathing mixtures as compared to air. We see no reason for reservations in the use of heliox breathing during treatment of air-diving-induced decompression sickness. PMID:21318313
5. Effect of hypobaric air, oxygen, heliox (50:50), or heliox (80:20) breathing on air bubbles in adipose tissue.
PubMed
2007-09-01
The fate of bubbles formed in tissues during decompression to altitude after diving or due to accidental loss of cabin pressure during flight has only been indirectly inferred from theoretical modeling and clinical observations with noninvasive bubble-measuring techniques of intravascular bubbles. In this report we visually followed the in vivo resolution of micro-air bubbles injected into adipose tissue of anesthetized rats decompressed from 101.3 kPa to and held at 71 kPa corresponding to approximately 2.750 m above sea level, while the rats breathed air, oxygen, heliox (50:50), or heliox (80:20). During air breathing, bubbles initially grew for 30-80 min, after which they remained stable or began to shrink slowly. Oxygen breathing caused an initial growth of all bubbles for 15-85 min, after which they shrank until they disappeared from view. Bubble growth was significantly greater during breathing of oxygen compared with air and heliox breathing mixtures. During heliox (50:50) breathing, bubbles initially grew for 5-30 min, from which point they shrank until they disappeared from view. After a shift to heliox (80:20) breathing, some bubbles grew slightly for 20-30 min, then shrank until they disappeared from view. Bubble disappearance was significantly faster during breathing of oxygen and heliox mixtures compared with air. In conclusion, the present results show that oxygen breathing at 71 kPa promotes bubble growth in lipid tissue, and it is possible that breathing of heliox may be beneficial in treating decompression sickness during flight. PMID:17600159
6. Direct AFM force measurements between air bubbles in aqueous monodisperse sodium poly(styrene sulfonate) solutions.
PubMed
Browne, Christine; Tabor, Rico F; Grieser, Franz; Dagastine, Raymond R
2015-08-01
Structural forces play an important role in the rheology, processing and stability of colloidal systems and complex fluids, with polyelectrolytes representing a key class of structuring colloids. Here, we explore the interactions between soft colloids, in the form of air bubbles, in solutions of monodisperse sodium poly(styrene sulfonate) as a model polyelectrolyte. It is found that by self-consistently modelling the force oscillations due to structuring of the polymer chains along with deformation of the bubbles, it is possible to precisely predict the interaction potential between approaching bubbles. In line with polyelectrolyte scaling theory, two distinct regimes of behaviour are seen, corresponding to dilute and semi-dilute polymer solutions. It is also seen that by blending monodisperse systems to give a bidisperse sample, the interaction forces between soft colloids can be controlled with a high degree of precision. At increasing bubble collision velocity, it is revealed that hydrodynamic flow overwhelms oscillatory structural interactions, showing the important disparity between equilibrium behaviour and dynamic interactions. PMID:25881266
7. Arrested Bubble Rise in a Narrow Tube
Lamstaes, Catherine; Eggers, Jens
2016-06-01
If a long air bubble is placed inside a vertical tube closed at the top it can rise by displacing the fluid above it. However, Bretherton found that if the tube radius, R, is smaller than a critical value Rc=0.918 ℓ_c , where ℓ_c=√{γ /ρ g} is the capillary length, there is no solution corresponding to steady rise. Experimentally, the bubble rise appears to have stopped altogether. Here we explain this observation by studying the unsteady bubble motion for Rbubble and the tube goes to zero in limit of large t like t^{-4/5} , leading to a rapid slow-down of the bubble's mean speed U ∝ t^{-2} . As a result, the total bubble rise in infinite time remains very small, giving the appearance of arrested motion.
8. The effect of water temperature on air entrainment, bubble plumes, and surface foam in a laboratory breaking-wave analog
Callaghan, A. H.; Stokes, M. D.; Deane, G. B.
2014-11-01
Air-entraining breaking waves form oceanic whitecaps and play a key role in climate regulation through air-sea bubble-mediated gas transfer, and sea spray aerosol production. The effect of varying sea surface temperature on air entrainment, subsurface bubble plume dynamics, and surface foam evolution intrinsic to oceanic whitecaps has not been well studied. By using a breaking wave analog in the laboratory over a range of water temperatures (Tw = 5°C to Tw = 30°C) and different source waters, we have examined changes in air entrainment, subsurface bubble plumes, and surface foam evolution over the course of a breaking event. For filtered seawater, air entrainment was estimated to increase by 6% between Tw = 6°C and Tw = 30°C, driven by increases of about 43% in the measured surface roughness of the plunging water sheet. After active air entrainment, the rate of loss of air through bubble degassing was more rapid at colder water temperatures within the first 0.5 s of plume evolution. Thereafter, the trend reversed and bubbles degassed more quickly in warmer water. The largest observed temperature-dependent differences in subsurface bubble distributions occurred at radii greater than about 700 μm. Temperature-dependent trends observed in the subsurface bubble plume were mirrored in the temporal evolution of the surface whitecap foam area demonstrating the intrinsic link between surface whitecap foam and the subsurface bubble plume. Differences in foam and plume characteristics due to different water sources were greater than the temperature dependencies for the filtered seawater examined.
9. Fluorescence light microscopy of pulmonary surfactant at the air-water interface of an air bubble of adjustable size.
PubMed
Knebel, D; Sieber, M; Reichelt, R; Galla, H-J; Amrein, M
2002-07-01
The structural dynamics of pulmonary surfactant was studied by epifluorescence light microscopy at the air-water interface of a bubble as a model close to nature for an alveolus. Small unilamellar vesicles of dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylglycerol, a small amount of a fluorescent dipalmitoylphosphatidylcholine-analog, and surfactant-associated protein C were injected into the buffer solution. They aggregated to large clusters in the presence of Ca(2+) and adsorbed from these units to the interface. This gave rise to an interfacial film that eventually became fully condensed with dark, polygonal domains in a fluorescent matrix. When now the bubble size was increased or decreased, respectively, the film expanded or contracted. Upon expansion of the bubble, the dark areas became larger to the debit of the bright matrix and reversed upon contraction. We were able to observe single domains during the whole process. The film remained condensed, even when the interface was increased to twice its original size. From comparison with scanning force microscopy directly at the air-water interface, the fluorescent areas proved to be lipid bilayers associated with the (dark) monolayer. In the lung, such multilayer phase acts as a reservoir that guarantees a full molecular coverage of the alveolar interface during the breathing cycle and provides mechanical stability to the film. PMID:12080141
10. Hydrodynamic effects of air sparging on hollow fiber membranes in a bubble column reactor.
PubMed
Xia, Lijun; Law, Adrian Wing-Keung; Fane, Anthony G
2013-07-01
Air sparging is now a standard approach to reduce concentration polarization and fouling of membrane modules in membrane bioreactors (MBRs). The hydrodynamic shear stresses, bubble-induced turbulence and cross flows scour the membrane surfaces and help reduce the deposit of foulants onto the membrane surface. However, the detailed quantitative knowledge on the effect of air sparging remains lacking in the literature due to the complex hydrodynamics generated by the gas-liquid flows. To date, there is no valid model that describes the relationship between the membrane fouling performance and the flow hydrodynamics. The present study aims to examine the impact of hydrodynamics induced by air sparging on the membrane fouling mitigation in a quantitative manner. A modelled hollow fiber module was placed in a cylindrical bubble column reactor at different axial heights with the trans-membrane pressure (TMP) monitored under constant flux conditions. The configuration of bubble column without the membrane module immersed was identical to that studied by Gan et al. (2011) using Phase Doppler Anemometry (PDA), to ensure a good quantitative understanding of turbulent flow conditions along the column height. The experimental results showed that the meandering flow regime which exhibits high flow instability at the 0.3 m is more beneficial to fouling alleviation compared with the steady flow circulation regime at the 0.6 m. The filtration tests also confirmed the existence of an optimal superficial air velocity beyond which a further increase is of no significant benefit on the membrane fouling reduction. In addition, the alternate aeration provided by two air stones mounted at the opposite end of the diameter of the bubble column was also studied to investigate the associated flow dynamics and its influence on the membrane filtration performance. It was found that with a proper switching interval and membrane module orientation, the membrane fouling can be effectively
11. An air-bubble-actuated micropump for on-chip blood transportation.
PubMed
Chiu, Sheng-Hung; Liu, Cheng-Hsien
2009-06-01
A novel electrolysis-based micropump using air bubbles to achieve indirect actuation is proposed and demonstrated. Compared with other electrochemical micropumps, our micropump can drive microfluids without inducing the pH value variation in the main channel and the choking/sticking phenomena of electrolytic bubbles. It is promising for biomedical applications, especially for blood transportation. Our proposed on-chip electrolysis-bubble actuator with the features of room temperature operation, low driving voltage, low power consumption and large actuation force not only can minimize the possibility of cell-damage but also may enable portable and implantable lab-on-a-chip microsystems. Utilizing our proposed hydrophobic trapeziform pattern located at the junction of the T-shaped microchannel, the micropump makes the pumped fluid in the main channel be isolated from the electrolytic bubbles. It can be used for a variety of applications without the constraints on the pumped liquid. Experimental results show that the liquid displacement and the pumping rate could be easily and accurately controlled via the signal of a two-phase peristaltic sequence and the periodic generation of electrolytic bubbles. With an applied voltage of 2.5 V, the maximum pumping rate for DI water and whole blood were 121 nl min(-1) and 88 nl min(-1), respectively, with a channel cross section of 100 x 50 microm. Maximum back-pressure of 16 kPa and 11 kPa for DI water and whole blood, respectively, were achieved in our present prototype chips. PMID:19458858
12. Bubble Combustion
NASA Technical Reports Server (NTRS)
Corrigan, Jackie
2004-01-01
, a computational model developed at Glenn, that simulates the cavitational collapse of a single bubble in a liquid (water) and the subsequent combustion of the gaseous contents inside the bubble. The model solves the time-dependent, compressible Navier-Stokes equations in one-dimension with finite-rate chemical kinetics using the CHEMKIN package. Specifically, parameters such as frequency, pressure, bubble radius, and the equivalence ratio were varied while examining their effect on the maximum temperature, radius, and chemical species. These studies indicate that the radius of the bubble is perhaps the most critical parameter governing bubble combustion dynamics and its efficiency. Based on the results of the parametric studies, we plan on conducting experiments to study the effect of ultrasonic perturbations on the bubble generation process with respect to the bubble radius and size distribution.
13. Calibration of a bubble evolution model to observed bubble incidence in divers.
PubMed
Gault, K A; Tikuisis, P; Nishi, R Y
1995-09-01
The method of maximum likelihood was used to calibrate a probabilistic bubble evolution model against data of bubbles detected in divers. These data were obtained from a diverse set of 2,064 chamber man-dives involving air and heliox with and without oxygen decompression. Bubbles were measured with Doppler ultrasound and graded according to the Kisman-Masurel code from which a single maximum bubble grade (BG) per diver was compared to the maximum bubble radius (Rmax) predicted by the model. This comparison was accomplished using multinomial statistics by relating BG to Rmax through a series of probability functions. The model predicted the formation of the bubble according to the critical radius concept and its evolution was predicted by assuming a linear rate of inert gas exchange across the bubble boundary. Gas exchange between the model compartment and blood was assumed to be perfusion-limited. The most successful calibration of the model was found using a trinomial grouping of BG according to no bubbles, low, and high bubble activity, and by assuming a single tissue compartment. Parameter estimations converge to a tissue volume of 0.00036 cm3, a surface tension of 5.0 dyne.cm-1, respective time constants of 27.9 and 9.3 min for nitrogen and helium, and respective Ostwald tissue solubilities of 0.0438 and 0.0096. Although not part of the calibration algorithm, the predicted evolution of bubble size compares reasonably well with the temporal recordings of BGs. PMID:7580766
14. Trapping of Sodium Dodecyl Sulfate at the Air-Water Interface of Oscillating Bubbles.
PubMed
Corti, Mario; Pannuzzo, Martina; Raudino, Antonio
2015-06-16
We report that at very low initial bulk concentrations, a couple of hundred times below the critical micellar concentration (CMC), anionic surfactant sodium dodecyl sulfate (SDS) adsorbed at the air-water interface of a gas bubble cannot be removed, on the time scale of the experiment (hours), when the surrounding solution is gently replaced by pure water. Extremely sensitive interferometric measurements of the resonance frequency of the bubble-forced oscillations give precise access to the concentration of the surfactant monolayer. The bulk-interface dynamic exchange of SDS molecules is shown to be inhibited below a concentration which we believe refers to a kind of gas-liquid phase transition of the surface monolayer. Above this threshold we recover the expected concentration-dependent desorption. The experimental observations are interpreted within simple energetic considerations supported by molecular dynamics (MD) calculations. PMID:26039913
15. Interfacial structures of confined air-water two-phase bubbly flow
SciTech Connect
Kim, S.; Ishii, M.; Wu, Q.; McCreary, D.; Beus, S.G.
2000-08-01
The interfacial structure of the two-phase flows is of great importance in view of theoretical modeling and practical applications. In the present study, the focus is made on obtaining detailed local two-phase parameters in the air-water bubbly flow in a rectangular vertical duct using the double-sensor conductivity probe. The characteristic wall-peak is observed in the profiles of the interracial area concentration and the void fraction. The development of the interfacial area concentration along the axial direction of the flow is studied in view of the interfacial area transport and bubble interactions. The experimental data is compared with the drift flux model with C{sub 0} = 1.35.
16. Observations of internal flow inside an evaporating nanofluid sessile droplet in the presence of an entrapped air bubble.
PubMed
Shin, Dong Hwan; Allen, Jeffrey S; Lee, Seong Hyuk; Choi, Chang Kyoung
2016-01-01
Using a unique, near-field microscopy technique, fringe patterns and nanoparticle motions are visualized immediately following a nanofluid droplet deposition on a glass substrate in which an air bubble is entrapped. The nanofluid consists of DI-water, 0.10% Aluminum Oxide nanoparticles with an average diameter of 50 nm, and 0.0005% yellow-green polystyrene fluorescent particles of 1 μm diameter. High-speed, fluorescent-mode confocal imaging enables investigation of depth-wise sectioned particle movements in the nanofluid droplet inside which a bubble is entrapped. The static contact angle is increased when a bubble is applied. In the presence of the bubble in the droplet, the observed flow toward the center of the droplet is opposite to the flow observed in a droplet without the bubble. When the bubble is present, the evaporation process is retarded. Also, random motion is observed in the contact line region instead of the typical evaporation-driven flow toward the droplet edge. Once the bubble bursts, however, the total evaporation time decreases due to the change in the contact line characteristics. Moreover, the area of fringe patterns beneath the bubble increases with time. Discussed herein is a unique internal flow that has not been observed in nanofluid droplet evaporation. PMID:27615999
17. Detection of micro-sized air bubble defects in optical glass based on Mie theory
Zhang, Sai; Bai, Jian; Wang, Kaiwei; He, Fan; Zhou, Bin
2015-10-01
Mie scattering theory was shown in this paper to be suitable for analyzing the forward scattered light intensity distribution of micro-sized air bubble defects in glass, shining by a monochrome laser with a wavelength of 532um. The scattered light was measured by a high definition CCD camera. The scattering process can be classified as uncorrelated single scattering according to the properties of optical media. After calculating and smoothing the gray value of split rings of picture, Chahine algorithm was applied to reverse the size of defects. This technique was accurate to within 5% for defects with radii of <50um.
18. Influence of water depth on the sound generated by air-bubble vibration in the water musical instrument
Ohuchi, Yoshito; Nakazono, Yoichi
2014-06-01
We have developed a water musical instrument that generates sound by the falling of water drops within resonance tubes. The instrument can give people who hear it the healing effect inherent in the sound of water. The sound produced by falling water drops arises from air- bubble vibrations. To investigate the impact of water depth on the air-bubble vibrations, we conducted experiments at varying values of water pressure and nozzle shape. We found that air-bubble vibration frequency does not change at a water depth of 50 mm or greater. Between 35 and 40 mm, however, the frequency decreases. At water depths of 30 mm or below, the air-bubble vibration frequency increases. In our tests, we varied the nozzle diameter from 2 to 4 mm. In addition, we discovered that the time taken for air-bubble vibration to start after the water drops start falling is constant at water depths of 40 mm or greater, but slower at depths below 40 mm.
19. Measuring forces and spatiotemporal evolution of thin water films between an air bubble and solid surfaces of different hydrophobicity.
PubMed
Shi, Chen; Cui, Xin; Xie, Lei; Liu, Qingxia; Chan, Derek Y C; Israelachvili, Jacob N; Zeng, Hongbo
2015-01-27
A combination of atomic force microscopy (AFM) and reflection interference contrast microscopy (RICM) was used to measure simultaneously the interaction force and the spatiotemporal evolution of the thin water film between a bubble in water and mica surfaces with varying degrees of hydrophobicity. Stable films, supported by the repulsive van der Waals-Casimir-Lifshitz force were always observed between air bubble and hydrophilic mica surfaces (water contact angle, θ(w) < 5°) whereas bubble attachment occurred on hydrophobized mica surfaces. A theoretical model, based on the Reynolds lubrication theory and the augmented Young-Laplace equation including the effects of disjoining pressure, provided excellent agreement with experiment results, indicating the essential physics involved in the interaction between air bubble and solid surfaces can be elucidated. A hydrophobic interaction free energy per unit area of the form: WH(h) = -γ(1 - cos θ(w))exp(-h/D(H)) can be used to quantify the attraction between bubble and hydrophobized solid substrate at separation, h, with γ being the surface tension of water. For surfaces with water contact angle in the range 45° < θ(w) < 90°, the decay length DH varied between 0.8 and 1.0 nm. This study quantified the hydrophobic interaction in asymmetric system between air bubble and hydrophobic surfaces, and provided a feasible method for synchronous measurements of the interaction forces with sub-nN resolution and the drainage dynamics of thin films down to nm thickness. PMID:25514470
20. Pachymetry-guided intrastromal air injection ("pachy-bubble") for deep anterior lamellar keratoplasty.
PubMed
Ghanem, Ramon C; Ghanem, Marcielle A
2012-09-01
To evaluate an innovative technique for intrastromal air injection to achieve deep anterior lamellar keratoplasty (DALK) with bare Descemet membrane (DM). Thirty-four eyes with anterior corneal pathology, including 27 with keratoconus, underwent DALK. After 400 μm trephination with a suction trephine, ultrasound pachymetry was performed 0.8 mm internally from the trephination groove in the 11 to 1 o'clock position. In this area, a 2-mm incision was created, parallel to the groove, with a micrometer diamond knife calibrated to 90% depth of the thinnest measurement. A cannula was inserted through the incision and 0.5 mL of air was injected to dissect the DM from the stroma. After peripheral paracentesis, anterior keratectomy was carried out to bare the DM. A 0.25-mm oversized graft was sutured in place. Overall, 94.1% of eyes achieved DALK. Bare DM was achieved in 30 eyes, and a pre-DM dissection was performed in 2 eyes. Air injection was successful in detaching the DM (achieving the big bubble) in 88.2% of the eyes. In keratoconus eyes, the rate was 88.9%. All cases but one required a single air injection to achieve DM detachment. Microperforations occurred in 5 cases: 3 during manual layer-by-layer dissection after air injection failed to detach the DM, 1 during removal of the residual stroma after big-bubble formation, and 1 during the diamond knife incision. Two cases (5.9%) were converted to penetrating keratoplasty because of macroperforations. The technique was reproducible, safe, and highly effective in promoting DALK with bare DM. PMID:22367050
1. Enriched Air Nitrox Breathing Reduces Venous Gas Bubbles after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial
PubMed Central
Souday, Vincent; Koning, Nick J.; Perez, Bruno; Grelon, Fabien; Mercat, Alain; Boer, Christa; Seegers, Valérie; Radermacher, Peter; Asfar, Pierre
2016-01-01
Objective To test the hypothesis whether enriched air nitrox (EAN) breathing during simulated diving reduces decompression stress when compared to compressed air breathing as assessed by intravascular bubble formation after decompression. Methods Human volunteers underwent a first simulated dive breathing compressed air to include subjects prone to post-decompression venous gas bubbling. Twelve subjects prone to bubbling underwent a double-blind, randomized, cross-over trial including one simulated dive breathing compressed air, and one dive breathing EAN (36% O2) in a hyperbaric chamber, with identical diving profiles (28 msw for 55 minutes). Intravascular bubble formation was assessed after decompression using pulmonary artery pulsed Doppler. Results Twelve subjects showing high bubble production were included for the cross-over trial, and all completed the experimental protocol. In the randomized protocol, EAN significantly reduced the bubble score at all time points (cumulative bubble scores: 1 [0–3.5] vs. 8 [4.5–10]; P < 0.001). Three decompression incidents, all presenting as cutaneous itching, occurred in the air versus zero in the EAN group (P = 0.217). Weak correlations were observed between bubble scores and age or body mass index, respectively. Conclusion EAN breathing markedly reduces venous gas bubble emboli after decompression in volunteers selected for susceptibility for intravascular bubble formation. When using similar diving profiles and avoiding oxygen toxicity limits, EAN increases safety of diving as compared to compressed air breathing. Trial Registration ISRCTN 31681480 PMID:27163253
2. Bubble pinch-off and scaling during liquid drop impact on liquid pool
Ray, Bahni; Biswas, Gautam; Sharma, Ashutosh
2012-08-01
Simulations are performed to show entrapment of air bubble accompanied by high speed upward and downward water jets when a water drop impacts a pool of water surface. A new bubble entrapment zone characterised by small bubble pinch-off and long thick jet is found. Depending on the bubble and jet behaviour, the bubble entrapment zone is subdivided into three sub-regimes. The entrapped bubble size and jet height depends on the crater shape and its maximum depth. During the bubble formation, bubble neck develops an almost singular shape as it pinches off. The final pinch-off shape and the power law governing the pinching, rneck ∝ A(t0 - t)αvaries with the Weber number. Weber dependence of the function describing the radius of the bubble during the pinch-off only affects the coefficient A and not the power exponent α.
3. Pixel-scale assessment and uncertainty analysis of AIRS and MODIS ice cloud optical thickness and effective radius
Kahn, B. H.; Schreier, M. M.; Yue, Q.; Fetzer, E. J.; Irion, F. W.; Platnick, S.; Wang, C.; Nasiri, S. L.; L'Ecuyer, T. S.
2015-11-01
Comparisons of collocated Atmospheric Infrared Sounder (AIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS) ice cloud optical thickness (τ) and effective radius (re) retrievals and their uncertainty estimates are described at the pixel scale. While an estimated 27% of all AIRS fields of view contain ice cloud, only 7% contain spatially uniform ice according to the MODIS 1 km optical property phase mask. The ice cloud comparisons are partitioned by horizontal variability in cloud amount, cloud top thermodynamic phase, vertical layering of clouds, and other parameters. The magnitudes of τ and re and their relative uncertainties are compared for a wide variety of pixel-scale cloud complexity. The correlations of τ and re between the two instruments are strong functions of horizontal cloud heterogeneity and vertical cloud structure, with the highest correlations found in single-layer, horizontally homogeneous clouds over the low-latitude tropical oceans. While the τ comparisons are essentially unbiased for homogeneous ice cloud with variability that depends on scene complexity, a bias of 5-10 µm remains in re within the most homogeneous scenes identified, consistent with known radiative transfer differences in the visible and infrared bands. The AIRS and MODIS uncertainty estimates reflect the wide variety of cloud complexity, with greater magnitudes in scenes with larger horizontal variability. The AIRS averaging kernels suggest scene-dependent information content that is consistent with infrared sensitivity to ice clouds. The AIRS-normalized χ2 radiance fits suggest that accounting for horizontal cloud variability is likely to improve the AIRS ice cloud retrievals.
4. Variation of Local Surface Properties of an Air Bubble in Water Caused by Its Interaction with Another Surface.
PubMed
Del Castillo, Lorena A; Ohnishi, Satomi; Carnie, Steven L; Horn, Roger G
2016-08-01
Surface and hydrodynamic forces acting between an air bubble and a flat mica surface in surfactant-free water and in 1 mM KCl solution have been investigated by observing film drainage using a modified surface force apparatus (SFA). The bubble shapes observed with the SFA are compared to theoretical profiles computed from a model that considers hydrodynamic interactions, surface curvature, and disjoining pressure arising from electrical double layer and van der Waals interactions. It is shown that the bubble experiences double-layer forces, and a final equilibrium wetting film between the bubble and mica surfaces is formed by van der Waals repulsion. However, comparison with the theoretical model reveals that the double-layer forces are not simply a function of surface separation. Rather, they appear to be changed by one of more of the following: the bubble's dynamic deformation, its proximity to another surface, and/or hydrodynamic flow in the aqueous film that separate them. The same comments apply to the hydrodynamic mobility or immobility of the air-water interface. Together the results show that the bubble's surface is "soft" in two senses: in addition to its well-known deformability, its local properties are affected by weak external forces, in this case the electrical double-layer interactions with a nearby surface and hydrodynamic flow in the neighboring aqueous phase. PMID:27391417
5. Is mudflow in Sidoarjo, East Java due to the pumping mechanism of hot air bubbles? : Laboratory simulations and field observations
Nurhandoko, Bagus Endar B.
2015-09-01
Extraordinary mudflow has happened in Sidoarjo, East Java, Indonesia since 2006. This mud comes from the giant crater that is located close to the BJP - 01. Thousands of homes have been submerged due to mudflow. Till today this giant mud crater is still has great strength despite the mud flowing over 8 years. This is a very rare phenomenon in the world. This mud flow mechanism raises big questions, because it has been going on for years, naturally the mudflow will stop by itself because the pressure should be reduced. This research evaluates all aspects of integrated observations, laboratory tests and field observations since the beginning of this ongoing mudflow. Laboratory tests were done by providing hot air bubbles into the fluid inside the inverted funnel showed that the fluid can flow with a high altitude. It is due to the mechanism of buoyant force from air bubbles to the water where the contrast density of the water and the air is quite large. Quantity of air bubbles provides direct effect to the debit of fluid flow. Direct observation in the field, in 2006 and 2007, with TIMNAS and LPPM ITB showed the large number of air bubbles on the surface of the mud craters. Temperature observation on the surface of mud crater is around 98 degree C whereas at greater depth shows the temperature is increasingly rising. This strengthens the hypothesis or proves that the mud pumping mechanism comes from buoyant force of hot air bubbles. Inversion gravity images show that the deep subsurface of main crater is close to volcanic layers or root of Arjuna mountain. Based on the simulation laboratory and field observation data, it can be concluded that the geothermal factor plays a key role in the mudflow mechanism.
6. Turbulent hydraulic jumps: Effect of Weber number and Reynolds number on air entrainment and micro-bubble generation
2015-11-01
Air entrainment in breaking waves is a ubiquitous and complex phenomenon. It is the main source of air transfer from atmosphere to the oceans. Furthermore, air entrainment due to ship-induced waves contributes to bubbly flows in ship wakes and also affect their performance. In this study, we consider a turbulent hydraulic jump as a canonical setting to investigate air entrainment due to turbulence-wave interactions. The flow has an inlet Froude number of 2.0, while three different Weber numbers (We = 1820, 729, 292), and two different Reynolds numbers (Re = 11000, 5500) based on the inlet height and inlet velocity are investigated. Air entrainment is shown to be very sensitive to the We number, while Re number has a minor effect. Wave breaking and interface collisions are significantly reduced in the low Weber number cases. As a result, micro-bubble generation is significantly reduced with decreasing Weber number. Vortex shedding events are observed to emerge at the toe of the jump in all of the cases. For high Weber number regimes, shedding of vortices is accompanied by engulfment of air pockets into the jump in a periodic manner, while for lower Webber number regimes such events are significantly suppressed. Reynolds number is shown to have a negligible effect on the air entrainment, wave breaking and micro-bubble generation, contrary to the previous assumptions in other studies. Supported by ONR.
7. Hydrophobically-associating cationic polymers as micro-bubble surface modifiers in dissolved air flotation for cyanobacteria cell separation.
PubMed
Yap, R K L; Whittaker, M; Diao, M; Stuetz, R M; Jefferson, B; Bulmus, V; Peirson, W L; Nguyen, A V; Henderson, R K
2014-09-15
Dissolved air flotation (DAF), an effective treatment method for clarifying algae/cyanobacteria-laden water, is highly dependent on coagulation-flocculation. Treatment of algae can be problematic due to unpredictable coagulant demand during blooms. To eliminate the need for coagulation-flocculation, the use of commercial polymers or surfactants to alter bubble charge in DAF has shown potential, termed the PosiDAF process. When using surfactants, poor removal was obtained but good bubble adherence was observed. Conversely, when using polymers, effective cell removal was obtained, attributed to polymer bridging, but polymers did not adhere well to the bubble surface, resulting in a cationic clarified effluent that was indicative of high polymer concentrations. In order to combine the attributes of both polymers (bridging ability) and surfactants (hydrophobicity), in this study, a commercially-available cationic polymer, poly(dimethylaminoethyl methacrylate) (polyDMAEMA), was functionalised with hydrophobic pendant groups of various carbon chain lengths to improve adherence of polymer to a bubble surface. Its performance in PosiDAF was contrasted against commercially-available poly(diallyl dimethyl ammonium chloride) (polyDADMAC). All synthesised polymers used for bubble surface modification were found to produce positively charged bubbles. When applying these cationic micro-bubbles in PosiDAF, in the absence of coagulation-flocculation, cell removals in excess of 90% were obtained, reaching a maximum of 99% cell removal and thus demonstrating process viability. Of the synthesised polymers, the polymer containing the largest hydrophobic functionality resulted in highly anionic treated effluent, suggesting stronger adherence of polymers to bubble surfaces and reduced residual polymer concentrations. PMID:24934266
8. Surfactant effects on cumulative drop size distributions produced by air bubbles bursting on a non-quiescent free surface
Parmar, K.; Liu, X.; Duncan, J. H.
2013-11-01
The generation of droplets when air bubbles travel upwards from within a liquid and burst at a free surface is studied experimentally. The bubbles are generated in a glass water tank that is 0.91 m long and 0.46 m wide with a water depth of 0.5 m. The tank is equipped with an acrylic box at its bottom that creates the bubble field using filtered air injected through an array of 180 hypodermic needles (0.33 mm ID). Two different surface conditions are created by using clean water and a 0.4% aqueous solution of Triton X-100 surfactant. Measurements of the bubble diameters as they approach the free surface are obtained with diffuse light shadowgraph images. The range of bubble diameters studied is 2.885 mm to 3.301 mm for clean water and 2.369 mm to 3.014 mm for the surfactant solution. A laser-light high-speed cinematic shadowgraph system is employed to record and measure the diameters and motions of the droplets at the free surface. This system can measure droplets with diameters <= 50 μm. The results show a clear distinction between the droplet distributions obtained in clean water and the surfactant solution. A bimodal droplet distribution is observed for clean water with at least two dominating peaks. For the surfactant solution, a single distribution peak is seen. This work is supported by the National Science Foundation, Division of Ocean Sciences.
9. Ring Bubbles of Dolphins
NASA Technical Reports Server (NTRS)
Shariff, Karim; Marten, Ken; Psarakos, Suchi; White, Don J.; Merriam, Marshal (Technical Monitor)
1996-01-01
The article discusses how dolphins create and play with three types of air-filled vortices. The underlying physics is discussed. Photographs and sketches illustrating the dolphin's actions and physics are presented. The dolphins engage in this behavior on their own initiative without food reward. These behaviors are done repeatedly and with singleminded effort. The first type is the ejection of bubbles which, after some practice on the part of the dolphin, turn into toroidal vortex ring bubbles by the mechanism of baroclinic torque. These bubbles grow in radius and become thinner as they rise vertically to the surface. One dolphin would blow two in succession and guide them to fuse into one. Physicists call this a vortex reconnection. In the second type, the dolphins first create an invisible vortex ring in the water by swimming on their side and waving their tail fin (also called flukes) vigorously. This vortex ring travels horizontally in the water. The dolphin then turns around, finds the vortex and injects a stream of air into it from its blowhole. The air "fills-out" the core of the vortex ring. Often, the dolphin would knock-off a smaller ring bubble from the larger ring (this also involves vortex reconnection) and steer the smaller ring around the tank. One other dolphin employed a few other techniques for planting air into the fluke vortex. One technique included standing vertically in the water with tail-up, head-down and tail piercing the free surface. As the fluke is waved to create the vortex ring, air is entrained from above the surface. Another technique was gulping air in the mouth, diving down, releasing air bubbles from the mouth and curling them into a ring when they rose to the level of the fluke. In the third type, demonstrated by only one dolphin, the longitudinal vortex created by the dorsal fin on the back is used to produce 10-15 foot long helical bubbles. In one technique she swims in a curved path. This creates a dorsal fin vortex since
10. Gas bubble dimensions in Archean lava flows indicate low air pressure at 2.7 Ga
Som, S. M.; Buick, R.; Hagadorn, J.; Blake, T.; Perreault, J.; Harnmeijer, J.; Catling, D. C.
2014-12-01
Air pressure constrains atmospheric composition, which, in turn, is linked to the Earth system through biogeochemical cycles and fluxes of volatiles from and to the Earth's interior. Previous studies have only placed maximum levels on surface air pressure for the early Earth [1]. Here, we calculate an absolute value for Archean barometric pressure using gas bubble size (vesicle) distributions in uninflated basaltic lava flows that solidified at sea level 2.7 billion years ago in the Pilbara Craton, Western Australia. These vesicles have been filled in by secondary minerals deposited during metasomatism and so are now amydules, but thin sections show that infilling did not change vesicle dimensions. Amygdule dimensions are measured using high-resolution X-ray tomography from core samples obtained from the top and bottom of the lava flows. The modal size expressed at the top and at the bottom of an uninflated flow can be linked to atmospheric pressure using the ideal gas law. Such a technique has been verified as a paleoaltimeter using Hawaiian Quaternary lava flows [2]. We use statistical methods to estimate the mean and standard deviation of the volumetric size of the amygdules by applying 'bootstrap'resampling and the Central Limit Theorem. Our data indicate a surprisingly low atmospheric pressure. Greater nitrogen burial under anaerobic conditions likely explains lower pressure. Refs: [1] Som et al. (2012) Nature 484, 359-262. D. L. Sahagian et al. (2002) J. Geol., 110, 671-685.
11. Field-scale tests for determining mixing patterns associated with coarse-bubble air diffuser configurations, Egan Quarry, Illinois
USGS Publications Warehouse
Hornewer, N.J.; Johnson, G.P.; Robertson, D.M.; Hondzo, Miki
1997-01-01
The U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers, Chicago District did field-scale tests in August-September 1996 to determine mixing patterns associated with different configurations of coarse-bubble air diffusers. The tests were done in an approximately 13-meter deep quarry near Chicago, Ill. Three-dimensional velocity, water-temperature, dissolved oxygen concentration, and specific-conductivity profiles were collected from locations between approximately 2 to 30 meters from the diffusers for two sets of five test configurations; one set for stratified and one set for destratified conditions in the quarry. The data-collection methods and instrumentation used to characterize mixing patterns and interactions of coarse-bubble diffusers were successful. An extensive data set was collected and is available to calibrate and verify aeration and stratification models, and to characterize basic features of bubble-plume interaction.
12. Preliminary investigation of air bubbling and dietary sulfur reduction to mitigate hydrogen sulfide and odor from swine waste.
PubMed
Clark, O Grant; Morin, Brent; Zhang, Yongcheng; Sauer, Willem C; Feddes, John J R
2005-01-01
When livestock manure slurry is agitated, the sudden release of hydrogen sulfide (H(2)S) can raise concentrations to dangerous levels. Low-level air bubbling and dietary S reduction were evaluated as methods for reducing peak H(2)S emissions from swine (Sus scrofa) manure slurry samples. In a first experiment, 15-L slurry samples were stored in bench-scale digesters and continuously bubbled with air at 0 (control), 5, or 10 mL min(-1) for 28 d. The 5-L headspace of each digester was also continuously ventilated at 40 mL min(-1) and the mean H(2)S concentration in the outlet air was <10 microL L(-1). On Day 28, the slurry was agitated suddenly. The peak H(2)S concentration exceeded instrument range (>120 microL L(-1)) from the control treatment, and was 47 and 3.4 microL L(-1) for the 5 and 10 mL min(-1) treatments, respectively. In a second experiment, individually penned barrows were fed rations with dietary S concentrations of 0.34, 0.24, and 0.15% (w/w). Slurry derived from each diet was bubbled with air in bench-scale digesters, as before, at 10 mL min(-1) for 12 d and the mean H(2)S concentration in the digester outlet air was 11 microL L(-1). On Day 12, the slurry was agitated but the H(2)S emissions did not change significantly. Both low-level bubbling of air through slurry and dietary S reduction appear to be viable methods for reducing peak H(2)S emissions from swine manure slurry at a bench scale, but these approaches must be validated at larger scales. PMID:16221821
13. Extreme conditions in a dissolving air nanobubble
Yasui, Kyuichi; Tuziuti, Toru; Kanematsu, Wataru
2016-07-01
Numerical simulations of the dissolution of an air nanobubble in water have been performed taking into account the effect of bubble dynamics (inertia of the surrounding liquid). The presence of stable bulk nanobubbles is not assumed in the present study because the bubble radius inevitably passes the nanoscale in the complete dissolution of a bubble. The bubble surface is assumed to be clean because attachment of hydrophobic materials on the bubble surface could considerably change the gas diffusion rate. The speed of the bubble collapse (the bubble wall speed) increases to about 90 m/s or less. The shape of a bubble is kept nearly spherical because the amplitude of the nonspherical component of the bubble shape is negligible compared to the instantaneous bubble radius. In other words, a bubble never disintegrates into daughter bubbles during the dissolution. At the final moment of the dissolution, the temperature inside a bubble increases to about 3000 K due to the quasiadiabatic compression. The bubble temperature is higher than 1000 K only for the final 19 ps. However, the Knudsen number is more than 0.2 for this moment, and the error associated with the continuum model should be considerable. In the final 2.3 ns, only nitrogen molecules are present inside a bubble as the solubility of nitrogen is the lowest among the gas species. The radical formation inside a bubble is negligible because the probability of nitrogen dissociation is only on the order of 10-15. The pressure inside a bubble, as well as the liquid pressure at the bubble wall, increases to about 5 GPa at the final moment of dissolution. The pressure is higher than 1 GPa for the final 0.7 ns inside a bubble and for the final 0.6 ns in the liquid at the bubble wall. The liquid temperature at the bubble wall increases to about 360 K from 293 K at the final stage of the complete dissolution.
14. Extreme conditions in a dissolving air nanobubble.
PubMed
Yasui, Kyuichi; Tuziuti, Toru; Kanematsu, Wataru
2016-07-01
Numerical simulations of the dissolution of an air nanobubble in water have been performed taking into account the effect of bubble dynamics (inertia of the surrounding liquid). The presence of stable bulk nanobubbles is not assumed in the present study because the bubble radius inevitably passes the nanoscale in the complete dissolution of a bubble. The bubble surface is assumed to be clean because attachment of hydrophobic materials on the bubble surface could considerably change the gas diffusion rate. The speed of the bubble collapse (the bubble wall speed) increases to about 90 m/s or less. The shape of a bubble is kept nearly spherical because the amplitude of the nonspherical component of the bubble shape is negligible compared to the instantaneous bubble radius. In other words, a bubble never disintegrates into daughter bubbles during the dissolution. At the final moment of the dissolution, the temperature inside a bubble increases to about 3000 K due to the quasiadiabatic compression. The bubble temperature is higher than 1000 K only for the final 19 ps. However, the Knudsen number is more than 0.2 for this moment, and the error associated with the continuum model should be considerable. In the final 2.3 ns, only nitrogen molecules are present inside a bubble as the solubility of nitrogen is the lowest among the gas species. The radical formation inside a bubble is negligible because the probability of nitrogen dissociation is only on the order of 10^{-15}. The pressure inside a bubble, as well as the liquid pressure at the bubble wall, increases to about 5 GPa at the final moment of dissolution. The pressure is higher than 1 GPa for the final 0.7 ns inside a bubble and for the final 0.6 ns in the liquid at the bubble wall. The liquid temperature at the bubble wall increases to about 360 K from 293 K at the final stage of the complete dissolution. PMID:27575216
15. Exploring Bubbles
O'Geary, Melissa A.
Bubbles provide an enjoyable and festive medium through which to teach many concepts within the science topics of light, color, chemistry, force, air pressure, electricity, buoyancy, floating, density, among many others. In order to determine the nature of children's engagement within a museum setting and the learning opportunities of playing with bubbles, I went to a children's interactive museum located in a metropolitan city in the Northeastern part of the United States.
16. Cold Heat Release Characteristics of Solidified Oil Droplet-Water Solution Latent Heat Emulsion by Air Bubbles
Inaba, Hideo; Morita, Shin-Ichi
The present work investigates the cold heat-release characteristics of the solidified oil droplets (tetradecane, C14H30, freezing point 278.9 K)/water solution emulsion as a latent heat-storage material having a low melting point. An air bubbles-emulsion direct-contact heat exchange method is selected for the cold heat-results from the solidified oil droplet-emulsion layer. This type of direct-contact method results in the high thermal efficiency. The diameter of air bubbles in the emulsion increases as compared with that in the pure water. The air bubbles blown from a nozzle show a strong mixing behavior during rising in the emulsion. The temperature effectiveness, the sensible heat release time and the latent heat release time have been measured as experimental parameters. The useful nondimensional emulsion level equations for these parameters have been derived in terms of the nondimensional emalsion level expressed the emulsion layer dimensions, Reynolds number for air flow, Stefan number and heat capacity ratio.
17. Gasification of torrefied Miscanthus × giganteus in an air-blown bubbling fluidized bed gasifier.
PubMed
Xue, G; Kwapinska, M; Horvat, A; Kwapinski, W; Rabou, L P L M; Dooley, S; Czajka, K M; Leahy, J J
2014-05-01
Torrefaction is suggested to be an effective method to improve the fuel properties of biomass and gasification of torrefied biomass should provide a higher quality product gas than that from unprocessed biomass. In this study, both raw and torrefied Miscanthus × giganteus (M×G) were gasified in an air-blown bubbling fluidized bed (BFB) gasifier using olivine as the bed material. The effects of equivalence ratio (ER) (0.18-0.32) and bed temperature (660-850°C) on the gasification performance were investigated. The results obtained suggest the optimum gasification conditions for the torrefied M × G are ER 0.21 and 800°C. The product gas from these process conditions had a higher heating value (HHV) of 6.70 MJ/m(3), gas yield 2m(3)/kg biomass (H2 8.6%, CO 16.4% and CH4 4.4%) and cold gas efficiency 62.7%. The comparison between raw and torrefied M × G indicates that the torrefied M × G is more suitable BFB gasification. PMID:24681300
18. Gas bubbles in fossil amber as possible indicators of the major gas composition of ancient air
USGS Publications Warehouse
Berner, R.A.; Landis, G.P.
1988-01-01
Gases trapped in Miocene to Upper Cretaceous amber were released by gently crushing the amber under vacuum and were analyzed by quadrupole mass spectrometry. After discounting the possibility that the major gases N2, O2, and CO2 underwent appreciable diffusion and diagenetic exchange with their surroundings or reaction with the amber, it has been concluded that in primary bubbles (gas released during initial breakage) these gases represent mainly original ancient air modified by the aerobic respiration of microorganisms. Values of N2/(CO2+O2) for each time period give consistent results despite varying O2/CO2 ratios that presumably were due to varying degrees of respiration. This allows calculation of original oxygen concentrations, which, on the basis of these preliminary results, appear to have changed from greater than 30 percent O2 during one part ofthe Late Cretaceous (between 75 and 95 million years ago) to 21 percent during the Eocene-Oligocene and for present-day samples, with possibly lower values during the Oligocene-Early Miocene. Variable O2 levels over time in general confirm theoretical isotope-mass balance calculations and suggest that the atmosphere has evolved over Phanerozoic time.
19. Exploiting zone trapping to avoid liberation of air bubbles in flow-based analytical procedures requiring heating.
PubMed
Vida, Ana C F; Zagatto, Elias A G
2014-01-01
In flow-based analytical procedures requiring heating, liberation of air bubbles is avoided by trapping a sample selected portion into a heated hermetic environment. The flow-through cuvette is maintained into a temperature-controlled aluminium block, thus acting as the trapping element and allowing real-time monitoring. The feasibility of the innovation was demonstrated in the spectrophotometric catalytic determination of vanadium in mineral waters. Air bubbles were not released even for temperatures as high as 95°C. The proposed system handles about 25 samples per hour, requires only 3 mg p-anisidine per determination and yields precise results (r.s.d. = 2.1%), in agreement with ICP-MS. Detection limit was evaluated (3.3 σ criterion) as 0.1 μg L(-1) V. PMID:25109646
20. The use of an air bubble curtain to reduce the received sound levels for harbor porpoises (Phocoena phocoena).
PubMed
Lucke, Klaus; Lepper, Paul A; Blanchet, Marie-Anne; Siebert, Ursula
2011-11-01
In December 2005 construction work was started to replace a harbor wall in Kerteminde harbor, Denmark. A total of 175 wooden piles were piled into the ground at the waters edge over a period of 3 months. During the same period three harbor porpoises were housed in a marine mammal facility on the opposite side of the harbor. All animals showed strong avoidance reactions after the start of the piling activities. As a measure to reduce the sound exposure for the animals an air bubble curtain was constructed and operated in a direct path between the piling site and the opening of the animals' semi-natural pool. The sound attenuation effect achieved with this system was determined by quantitative comparison of pile driving impulses simultaneously measured in front of and behind the active air bubble curtain. Mean levels of sound attenuation over a sequence of 95 consecutive pile strikes were 14 dB (standard deviation (s.d.) 3.4 dB) for peak to peak values and 13 dB (s.d. 2.5 dB) for SEL values. As soon as the air bubble curtain was installed and operated, no further avoidance reactions of the animals to the piling activities were apparent. PMID:22088014
1. "Immortal" liquid film formed by colliding bubble at oscillating solid substrates
Zawala, Jan
2016-05-01
This paper presents an experimental study of the behavior of an ascending air bubble (equivalent radius 0.74 mm) colliding with a solid substrate. The substrate is either motionless or oscillating with a precisely adjusted acceleration, slightly higher than gravity. It is shown that the stability of the liquid film formed between the striking bubble and the solid surface depends not only on the hydrophobic/hydrophilic properties of the solid but also on the energetic interrelations in the system. The results indicate that the rupture of the bubble and its attachment at a smooth hydrophobic solid surface are related to the viscous dissipation of energy, leading to a gradual decrease in the bubble deformation, and in consequence in the radius of the formed separating liquid film. When the film radius is small enough, the bubble ruptures and attaches to the hydrophobic solid surface. Moreover, it is shown that when the bubble deformations are forced to be constant, by applying properly adjusted oscillations of the solid substrate (energy supply conditions), bubble rupture can be prevented and a constant bubble bouncing is observed, irrespective of the hydrophobic/hydrophilic properties of the solid substrate. Under such energy supply conditions, the liquid film can be considered "immortal." The numerical calculations performed for the respective system, in which constant kinetic energy is induced, confirm that the liquid film can persist indefinitely owing to its constant radius, which is too large to reach the critical thickness for rupture during the collision time.
2. Air bubble contact with endothelial cells in vitro induces calcium influx and IP3-dependent release of calcium stores
PubMed Central
Sobolewski, Peter; Kandel, Judith; Klinger, Alexandra L.
2011-01-01
Gas embolism is a serious complication of decompression events and clinical procedures, but the mechanism of resulting injury remains unclear. Previous work has demonstrated that contact between air microbubbles and endothelial cells causes a rapid intracellular calcium transient and can lead to cell death. Here we examined the mechanism responsible for the calcium rise. Single air microbubbles (50–150 μm), trapped at the tip of a micropipette, were micromanipulated into contact with individual human umbilical vein endothelial cells (HUVECs) loaded with Fluo-4 (a fluorescent calcium indicator). Changes in intracellular calcium were then recorded via epifluorescence microscopy. First, we confirmed that HUVECs rapidly respond to air bubble contact with a calcium transient. Next, we examined the involvement of extracellular calcium influx by conducting experiments in low calcium buffer, which markedly attenuated the response, or by pretreating cells with stretch-activated channel blockers (gadolinium chloride or ruthenium red), which abolished the response. Finally, we tested the role of intracellular calcium release by pretreating cells with an inositol 1,4,5-trisphosphate (IP3) receptor blocker (xestospongin C) or phospholipase C inhibitor (neomycin sulfate), which eliminated the response in 64% and 67% of cases, respectively. Collectively, our results lead us to conclude that air bubble contact with endothelial cells causes an influx of calcium through a stretch-activated channel, such as a transient receptor potential vanilloid family member, triggering the release of calcium from intracellular stores via the IP3 pathway. PMID:21633077
3. Buoyancy effects in steeply inclined air-water bubbly shear flow in a rectangular channel
Sanaullah, K.; Arshad, M.; Khan, A.; Chughtai, I. R.
2015-07-01
We report measurements of two-dimensional ( B/ D = 5) fully turbulent and developed duct flows (overall length/depth, L/ D = 60; D-based Reynolds number Re > 104) for inclinations to 30° from vertical at low voidages (< 5 % sectional average) representative of disperse regime using tap water bubbles (4-6 mm) and smaller bubbles (2 mm) stabilised in ionic solution. Pitot and static probe instrumentation, primitive but validated, provided adequate (10 % local value) discrimination of main aspects of the mean velocity and voidage profiles at representative streamwise station i.e L/ D = 40. Our results can be divided into three categories of behaviour. For vertical flow (0°) the evidence is inconclusive as to whether bubbles are preferentially trapped within the wall-layer as found in some, may be most earlier experimental works. Thus, the 4-mm bubbles showed indication of voidage retention but the 2-mm bubbles did not. For nearly vertical flow (5°) there was pronounced profiling of voidage especially with 4-mm bubbles but the transverse transport was not suppressed sufficiently to induce any obvious layering. In this context, we also refer to similarities with previous work on one-phase vertical and nearly vertical mixed convection flows displaying buoyancy inhibited mean shear turbulence. However, with inclined flow (10+ degrees) a distinctively layered pattern was invariably manifested in which voidage confinement increased with increasing inclination. In this paper we address flow behavior at near vertical conditions. Eulerian, mixed and VOF models were used to compute voidage and mean velocity profiles.
4. The effect of hydrodynamic interactions on the average properties of a bidisperse suspension of high Reynolds number, low Weber number bubbles
Kumaran, V.; Koch, Donald L.
1993-05-01
The hydrodynamic interaction between a pair of nondeformable bubbles (low Weber number limit) in potential flow (high Reynolds number limit) was analyzed. The velocity potential was determined using twin spherical expansions, and the equations of motion were calculated by enforcing the zero net force condition on the surface of the bubbles. The acceleration due to the interaction is expressed in a perturbation series in the parameter (ai/R), where ai is the radius of bubble i, R is the distance between the bubbles, and the leading-order acceleration was found to decrease as (ai/R)4. The effect of potential flow interactions on the trajectory of a pair of bubbles of different sizes (size ratio greater than 1.07 at a Reynolds number of 200) rising due to gravity was studied. A salient feature of the trajectories is that the surfaces of the bubble do not come into contact during the interaction, except when the smaller bubble radius is less than 0.233 times the larger bubble radius when the Reynolds number based on the larger bubble is 200. In the latter case, however, the Reynolds number based on the radius of the smaller bubble is not large enough to justify the potential flow approximation. For interactions where collisions do not occur, the mean-square fluctuating velocity in a uniform suspension and the hydrodynamic diffusivities in a nonuniform suspension were calculated by performing an ensemble average over pair interactions. The pair averaging procedure is valid for dilute suspensions (V≪18/Re, where V is the volume fraction of the bubbles and Re is the Reynolds number based on the bubble radius and its terminal velocity).
5. Aerator Combined With Bubble Remover
NASA Technical Reports Server (NTRS)
Dreschel, Thomas W.
1993-01-01
System produces bubble-free oxygen-saturated water. Bubble remover consists of outer solid-walled tube and inner hydrophobic, porous tube. Air bubbles pass from water in outer tube into inner tube, where sucked away. Developed for long-term aquaculture projects in space. Also applicable to terrestrial equipment in which entrained bubbles dry membranes or give rise to cavitation in pumps.
6. The Making of an Air-Supported Campus. Antioch's Bubble. Final Report.
ERIC Educational Resources Information Center
Brann, James
The inflation of the vinyl bubble by Antioch students and faculty climaxed more than a year of study, planning, dealing with contractors, county officials, manufacturers of equipment and materials--and maturing the technology of pneumatic buildings. These activities were combined into what Antioch calls a "process-oriented curriculum." This…
7. Sonoluminescence: Why fiery bubbles have eternal life
Lohse, Detlef; Brenner, Michael; Hilgenfeldt, Sascha
1996-11-01
Sound driven gas bubbles in water can emit light pulses. This phenomenon is called sonoluminescence (SL). Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL. Phase diagrams are presented in the gas concentration vs forcing pressure state space and also in the ambient radius vs forcing pressure state space. These phase diagrams are based on the thresholds for energy focusing in the bubble and on those for (i) shape instabilities and (ii) diffusive instabilities. Stable SL only occurs in a tiny parameter window of large forcing pressure amplitude Pa ~ 1.2 - 1.5atm and low gas concentration of less than 0.4% of saturation. The results quantitatively agree with experimental results of Putterman's UCLA group on argon, but not on air. However, air bubbles and other gas mixtures can also successfully be treated in this approach if in addition (iii) chemical instabilities are considered. The essential feature is the removal of almost all nitrogen and oxygen from the bubble through reaction to soluble compounds (i.e. NOx or NH_3).
8. The Speed of Axial Propagation of a Cylindrical Bubble Through a Cylindrical Vortex
NASA Technical Reports Server (NTRS)
Shariff, Karim; Mansour, Nagi N. (Technical Monitor)
2002-01-01
Inspired by the rapid elongation of air columns injected into vortices by dolphins, we present an exact inviscid solution for the axial speed (assumed steady) of propagation of the tip of a semi-infinite cylindrical bubble along the axis of a cylindrical vortex. The bubble is assumed to be held at constant pressure by being connected to a reservoir, the lungs of the dolphin, say. For a given bubble pressure, there is a modest critical rotation rate above which steadily propagating bubbles exist. For a bubble at ambient pressure, the propagation speed of the bubble (relative to axial velocity within the vortex) varies between 0.5 and 0.6 of the maximum rotational speed of the vortex. Surprisingly, the bubble tip can propagate (almost as rapidly) even when the pressure minimum in the vortex core is greater than the bubble pressure; in this case, solutions exhibit a dimple on the nose of the bubble. A situation important for incipient vortex cavitation, and one which dolphins also demonstrate, is elongation of a free bubble, i.e., one whose internal pressure may vary. Under the assumption that the acceleration term is small (checked a posteriori), the steady solution is applied at each instant during the elongation. Three types of behavior are then possible depending on physical parameters and initial conditions: (A) Unabated elongation with slowly increasing bubble pressure, and nearly constant volume. Volume begins to decrease in the late stages. (B1) Elongation with decreasing bubble pressure. A limit point of the steady solution is encountered at a finite bubble length. (B2) Unabated elongation with decreasing bubble pressure and indefinite creation of volume. This is made possible by the existence of propagating solutions at bubble pressures below the minimum vortex pressure. As the bubble stretches, its radius initially decreases but then becomes constant; this is also observed in experiments on incipient vortex cavitation.
9. The injection of air/oxygen bubble into the anterior chamber of rabbits as a treatment for hyphema in patients with sickle cell disease.
PubMed
Ayintap, Emre; Keskin, Uğurcan; Sadigov, Fariz; Coskun, Mesut; Ilhan, Nilufer; Motor, Sedat; Semiz, Hilal; Parlakfikirer, Nihan
2014-01-01
Purpose. To investigate the changes of partial oxygen pressure (PaO2) in aqueous humour after injecting air or oxygen bubble into the anterior chamber in sickle cell hyphema. Methods. Blood samples were taken from the same patient with sickle cell disease. Thirty-two rabbits were divided into 4 groups. In group 1 (n = 8), there was no injection. Only blood injection constituted group 2 (n = 8), both blood and air bubble injection constituted group 3 (n = 8), and both blood and oxygen bubble injection constituted group 4 (n = 8). Results. The PaO2 in the aqueous humour after 10 hours from the injections was 78.45 ± 9.9 mmHg (Mean ± SD) for group 1, 73.97 ± 8.86 mmHg for group 2, 123.35 ± 13.6 mmHg for group 3, and 306.47 ± 16.5 mmHg for group 4. There was statistically significant difference between group 1 and group 2, when compared with group 3 and group 4. Conclusions. PaO2 in aqueous humour was increased after injecting air or oxygen bubble into the anterior chamber. We offer to leave an air bubble in the anterior chamber of patients with sickle cell hemoglobinopathies and hyphema undergoing an anterior chamber washout. PMID:24808955
10. Direct AFM force measurements between air bubbles in aqueous polydisperse sodium poly(styrene sulfonate) solutions: effect of collision speed, polyelectrolyte concentration and molar mass.
PubMed
Browne, Christine; Tabor, Rico F; Grieser, Franz; Dagastine, Raymond R
2015-07-01
Interactions between colliding air bubbles in aqueous solutions of polydisperse sodium poly(styrene sulfonate) (NaPSS) using direct force measurements were studied. The forces measured with deformable interfaces were shown to be more sensitive to the presence of the polyelectrolytes when compared to similar measurements using rigid interfaces. The experimental factors that were examined were NaPSS concentration, bubble collision velocity and polyelectrolyte molar mass. These measurements were then compared with an analytical model based on polyelectrolyte scaling theory in order to explain the effects of concentration and bubble deformation on the interaction between bubbles. Typically structural forces from the presence of monodisperse polyelectrolyte between interacting surfaces may be expected, however, it was found that the polydispersity in molar mass resulted in the structural forces to be smoothed and only a depletion interaction was able to be measured between interacting bubbles. It was found that an increase in number density of NaPSS molecules resulted in an increase in the magnitude of the depletion interaction. Conversely this interaction was overwhelmed by an increase in the fluid flow in the system at higher bubble collision velocities. Polymer molar mass dispersity plays a significant role in the interactions present between the bubbles and has implications that also affect the polyelectrolyte overlap concentration of the solution. Further understanding of these implications can be expected to play a role in the improvement in operations in such fields as water treatment and mineral processing where polyelectrolytes are used extensively. PMID:25596872
11. Bubble Velocities in Slowly Sheared Bubble Rafts
Dennin, Michael
2004-03-01
Many complex fluids, such as foams, emulsions, colloids, and granular matter, exhibit interesting flow behavior when subjected to slow, steady rates of strain. The flow is characterized by irregular fluctuations in the stress with corresponding nonlinear rearrangements of the individual particles. We focus on the flow behavior of a model two-dimensional system: bubble rafts. Bubble rafts consist of a single layer of soap bubbles floating on the surface of a liquid subphase, usually a soap-water solution. The bubbles are sheared using a Couette geometry, i.e. concentric cylinders. We rotate the outer cylinder at a constant rate and measure the motions of individual bubbles and the stress on the inner cylinder. We will report on the velocity profiles of the bubbles averaged over long-times and averaged over individual stress events. The long-time average velocities are well described by continuum models for fluids with the one surprising feature that there exists a critical radius at which the shear-rate is discontinuous. The individual profiles are highly nonlinear and strongly correlated with the stress fluctuations. We will discuss a number of interesting questions. Can the average profiles be understood in a simple way given the individual velocities? Is there a clear "classification" for the individual profiles, or are they purely random? What sets the critical radius for a given set of flow conditions?
12. In Search of the Big Bubble
ERIC Educational Resources Information Center
Simoson, Andrew; Wentzky, Bethany
2011-01-01
Freely rising air bubbles in water sometimes assume the shape of a spherical cap, a shape also known as the "big bubble". Is it possible to find some objective function involving a combination of a bubble's attributes for which the big bubble is the optimal shape? Following the basic idea of the definite integral, we define a bubble's surface as…
13. Sonochemistry and bubble dynamics.
PubMed
Mettin, Robert; Cairós, Carlos; Troia, Adriano
2015-07-01
The details of bubble behaviour in chemically active cavitation are still not sufficiently well understood. Here we report on experimental high-speed observations of acoustically driven single-bubble and few-bubble systems with the aim of clarification of the connection of their dynamics with chemical activity. Our experiment realises the sonochemical isomerization reaction of maleic acid to fumaric acid, mediated by bromine radicals, in a bubble trap set-up. The main result is that the reaction product can only be observed in a parameter regime where a small bubble cluster occurs, while a single trapped bubble stays passive. Evaluations of individual bubble dynamics for both cases are given in form of radius-time data and numerical fits to a bubble model. A conclusion is that a sufficiently strong collapse has to be accompanied by non-spherical bubble dynamics for the reaction to occur, and that the reason appears to be an efficient mixing of liquid and gas phase. This finding corroborates previous observations and literature reports on high liquid phase sonochemical activity under distinct parameter conditions than strong sonoluminescence emissions. PMID:25194210
14. Importance of air bubbles in the core of coated pellets: Synchrotron X-ray microtomography allows for new insights.
PubMed
Fahier, J; Muschert, S; Fayard, B; Velghe, C; Byrne, G; Doucet, J; Siepmann, F; Siepmann, J
2016-09-10
High-resolution X-ray microtomography was used to get deeper insight into the underlying mass transport mechanisms controlling drug release from coated pellets. Sugar starter cores were layered with propranolol HCl and subsequently coated with Kollicoat SR, plasticized with 10% TEC. Importantly, synchrotron X-ray computed microtomography (SR-μCT) allowed direct, non-invasive monitoring of crack formation in the film coatings upon exposure to the release medium. Propranolol HCl, as well as very small sugar particles from the pellets' core, were expulsed through these cracks into the surrounding bulk fluid. Interestingly, SR-μCT also revealed the existence of numerous tiny, air-filled pores (varying in size and shape) in the pellet cores before exposure to the release medium. Upon water penetration into the system, the contents of the pellet cores became semi-solid/liquid. Consequently, the air-pockets became mobile and fused together. They steadily increased in size (and decreased in number). Importantly, "big" air bubbles were often located in close vicinity of a crack within the film coating. Thus, they play a potentially crucial role for the control of drug release from coated pellets. PMID:27374626
15. The dynamics of histotripsy bubbles
Kreider, Wayne; Bailey, Michael R.; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Crum, Lawrence A.
2011-09-01
Histotripsy describes treatments in which high-amplitude acoustic pulses are used to excite bubbles and erode tissue. Though tissue erosion can be directly attributed to bubble activity, the genesis and dynamics of bubbles remain unclear. Histotripsy lesions that show no signs of thermal coagulative damage have been generated with two different acoustic protocols: relatively long acoustic pulses that produce local boiling within milliseconds and relatively short pulses that are higher in amplitude but likely do not produce boiling. While these two approaches are often distinguished as boiling' versus cavitation', such labels can obscure similarities. In both cases, a bubble undergoes large changes in radius and vapor is transported into and out of the bubble as it oscillates. Moreover, observations from both approaches suggest that bubbles grow to a size at which they cease to collapse violently. In order to better understand the dynamics of histotripsy bubbles, a single-bubble model has been developed that couples acoustically excited bubble motions to the thermodynamic state of the surrounding liquid. Using this model for bubbles exposed to histotripsy sound fields, simulations suggest that two mechanisms can act separately or in concert to lead to the typically observed bubble growth. First, nonlinear acoustic propagation leads to the evolution of shocks and an asymmetry in the positive and negative pressures that drive bubble motion. This asymmetry can have a rectifying effect on bubble oscillations whereby the bubble grows on average during each acoustic cycle. Second, vapor transport to/from the bubble tends to produce larger bubbles, especially at elevated temperatures. Vapor transport by itself can lead to rectified bubble growth when the ambient temperature exceeds 100 °C (boiling') or local heating in the vicinity of the bubble leads to a superheated boundary layer.
16. Body fat does not affect venous bubble formation after air dives of moderate severity: theory and experiment.
PubMed
Schellart, Nico A M; van Rees Vellinga, Tjeerd P; van Hulst, Rob A
2013-03-01
For over a century, studies on body fat (BF) in decompression sickness and venous gas embolism of divers have been inconsistent. A major problem is that age, BF, and maximal oxygen consumption (Vo2max) show high multicollinearity. Using the Bühlmann model with eight parallel compartments, preceded by a blood compartment in series, nitrogen tensions and loads were calculated with a 40 min/3.1 bar (absolute) profile. Compared with Haldanian models, the new model showed a substantial delay in N2 uptake and (especially) release. One hour after surfacing, an increase of 14-28% in BF resulted in a whole body increase of the N2 load of 51%, but in only 15% in the blood compartment. This would result in an increase in the bubble grade of only 0.01 Kisman-Masurel (KM) units at the scale near KM = I-. This outcome was tested indirectly by a dry dive simulation (air breathing) with 53 male divers with a small range in age and Vo2max to suppress multicollinearity. BF was determined with the four-skinfold method. Precordial Doppler bubble grades determined at 40, 80, 120, and 160 min after surfacing were used to calculate the Kisman Integrated Severity Score and were also transformed to the logarithm of the number of bubbles/cm(2) (logB). The highest of the four scores yielded logB = -1.78, equivalent to KM = I-. All statistical outcomes of partial correlations with BF were nonsignificant. These results support the model outcomes. Although this and our previous study suggest that BF does not influence venous gas embolism (Schellart NAM, van Rees Vellinga TP, van Dijk FH, Sterk W. Aviat Space Environ Med 83: 951-957, 2012), more studies with different profiles under various conditions are needed to establish whether BF remains (together with age and Vo2max) a basic physical characteristic or will become less important for the medical examination and for risk assessment. PMID:23305985
17. A Subgrid Model for Predicting Air Entrainment Rates in Bubbly Flows
Ma, Jingsen; Oberai, Assad A.; Drew, Donald E.; Lahey, Richard T., Jr.; Moraga, Francisco J.
2008-11-01
In this talk we present a fairly simple subgrid air entrainment model that accurately predicts the rate of air entrainment, which is critical in simulating multiphase (air/water) flows. The derivation of this model begins by assuming that a thin sheet of air is carried into the water by the inertia of the liquid at the free surface. A momentum balance on the entrained gas layer results in an expression for the entrained volumetric gas flow rate, in terms of the local liquid velocity, gas viscosity etc., which are readily available from a multiphase RANS-type simulation. This model has been validated against extensive experimental data on both plunging jets and hydraulic jumps over a wide range of liquid velocities. It was implemented in a two-fluid computational fluid dynamics code (CFDShipM) to be used to predict the void fraction distribution underneath a plunging liquid jet at different depths and jet velocities. The results were found to match the experimental observations very well. The application of this model to more challenging problems, including hydraulic jumps and full-scale ship simulations, is currently underway.
18. Measurement and modeling on hydrodynamic forces and deformation of an air bubble approaching a solid sphere in liquids.
PubMed
Shahalami, Mansoureh; Wang, Louxiang; Wu, Chu; Masliyah, Jacob H; Xu, Zhenghe; Chan, Derek Y C
2015-03-01
The interaction between bubbles and solid surfaces is central to a broad range of industrial and biological processes. Various experimental techniques have been developed to measure the interactions of bubbles approaching solids in a liquid. A main challenge is to accurately and reliably control the relative motion over a wide range of hydrodynamic conditions and at the same time to determine the interaction forces, bubble-solid separation and bubble deformation. Existing experimental methods are able to focus only on one of the aspects of this problem, mostly for bubbles and particles with characteristic dimensions either below 100 μm or above 1 cm. As a result, either the interfacial deformations are measured directly with the forces being inferred from a model, or the forces are measured directly with the deformations to be deduced from the theory. The recently developed integrated thin film drainage apparatus (ITFDA) filled the gap of intermediate bubble/particle size ranges that are commonly encountered in mineral and oil recovery applications. Equipped with side-view digital cameras along with a bimorph cantilever as force sensor and speaker diaphragm as the driver for bubble to approach a solid sphere, the ITFDA has the capacity to measure simultaneously and independently the forces and interfacial deformations as a bubble approaches a solid sphere in a liquid. Coupled with the thin liquid film drainage modeling, the ITFDA measurement allows the critical role of surface tension, fluid viscosity and bubble approach speed in determining bubble deformation (profile) and hydrodynamic forces to be elucidated. Here we compare the available methods of studying bubble-solid interactions and demonstrate unique features and advantages of the ITFDA for measuring both forces and bubble deformations in systems of Reynolds numbers as high as 10. The consistency and accuracy of such measurement are tested against the well established Stokes-Reynolds-Young-Laplace model
19. A review of induction and attachment times of wetting thin films between air bubbles and particles and its relevance in the separation of particles by flotation.
PubMed
Albijanic, Boris; Ozdemir, Orhan; Nguyen, Anh V; Bradshaw, Dee
2010-08-11
Bubble-particle attachment in water is critical to the separation of particles by flotation which is widely used in the recovery of valuable minerals, the deinking of wastepaper, the water treatment and the oil recovery from tar sands. It involves the thinning and rupture of wetting thin films, and the expansion and relaxation of the gas-liquid-solid contact lines. The time scale of the first two processes is referred to as the induction time, whereas the time scale of the attachment involving all the processes is called the attachment time. This paper reviews the experimental studies into the induction and attachment times between minerals and air bubbles, and between oil droplets and air bubbles. It also focuses on the experimental investigations and mathematical modelling of elementary processes of the wetting film thinning and rupture, and the three-phase contact line expansion relevant to flotation. It was confirmed that the time parameters, obtained by various authors, are sensitive enough to show changes in both flotation surface chemistry and physical properties of solid surfaces of pure minerals. These findings should be extended to other systems. It is proposed that measurements of the bubble-particle attachment can be used to interpret changes in flotation behaviour or, in conjunction with other factors, such as particle size and gas dispersion, to predict flotation performance. PMID:20478547
20. The Bubbling Galactic Disk
Churchwell, E.; Povich, M. S.; Allen, D.; Taylor, M. G.; Meade, M. R.; Babler, B. L.; Indebetouw, R.; Watson, C.; Whitney, B. A.; Wolfire, M. G.; Bania, T. M.; Benjamin, R. A.; Clemens, D. P.; Cohen, M.; Cyganowski, C. J.; Jackson, J. M.; Kobulnicky, H. A.; Mathis, J. S.; Mercer, E. P.; Stolovy, S. R.; Uzpen, B.; Watson, D. F.; Wolff, M. J.
2006-10-01
A visual examination of the images from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) has revealed 322 partial and closed rings that we propose represent partially or fully enclosed three-dimensional bubbles. We argue that the bubbles are primarily formed by hot young stars in massive star formation regions. We have found an average of about 1.5 bubbles per square degree. About 25% of the bubbles coincide with known radio H II regions, and about 13% enclose known star clusters. It appears that B4-B9 stars (too cool to produce detectable radio H II regions) probably produce about three-quarters of the bubbles in our sample, and the remainder are produced by young O-B3 stars that produce detectable radio H II regions. Some of the bubbles may be the outer edges of H II regions where PAH spectral features are excited and may not be dynamically formed by stellar winds. Only three of the bubbles are identified as known SNRs. No bubbles coincide with known planetary nebulae or W-R stars in the GLIMPSE survey area. The bubbles are small. The distribution of angular diameters peaks between 1' and 3' with over 98% having angular diameters less than 10' and 88% less than 4'. Almost 90% have shell thicknesses between 0.2 and 0.4 of their outer radii. Bubble shell thickness increases approximately linearly with shell radius. The eccentricities are rather large, peaking between 0.6 and 0.7; about 65% have eccentricities between 0.55 and 0.85.
1. Sensitivity of Hollow Fiber Spacesuit Water Membrane Evaporator Systems to Potable Water Constituents, Contaminants and Air Bubbles
NASA Technical Reports Server (NTRS)
Bue, Grant C.; Trevino, Luis A.; Fritts, Sharon; Tsioulos, Gus
2008-01-01
The Spacesuit Water Membrane Evaporator (SWME) is the baseline heat rejection technology selected for development for the Constellation lunar suit. The first SWME prototype, designed, built, and tested at Johnson Space Center in 1999 used a Teflon hydrophobic porous membrane sheet shaped into an annulus to provide cooling to the coolant loop through water evaporation to the vacuum of space. This present study describes the test methodology and planning and compares the test performance of three commercially available hollow fiber materials as alternatives to the sheet membrane prototype for SWME, in particular, a porous hydrophobic polypropylene, and two variants that employ ion exchange through non-porous hydrophilic modified Nafion. Contamination tests will be performed to probe for sensitivities of the candidate SWME elements to ordinary constituents that are expected to be found in the potable water provided by the vehicle, the target feedwater source. Some of the impurities in potable water are volatile, such as the organics, while others, such as the metals and inorganic ions are nonvolatile. The non-volatile constituents will concentrate in the SWME as evaporated water from the loop is replaced by the feedwater. At some point in the SWME mission lifecycle as the concentrations of the non-volatiles increase, the solubility limits of one or more of the constituents may be reached. The resulting presence of precipitate in the coolant water may begin to plug pores and tube channels and affect the SWME performance. Sensitivity to macroparticles, lunar dust simulant, and air bubbles will also be investigated.
2. Acoustic radiation force on an air bubble and soft fluid spheres in ideal liquids: Example of a high-order Bessel beam of quasi-standing waves
Mitri, F. G.
2009-04-01
The partial wave series for the scattering of a high-order Bessel beam (HOBB) of acoustic quasi-standing waves by an air bubble and fluid spheres immersed in water and centered on the axis of the beam is applied to the calculation of the acoustic radiation force. A HOBB refers to a type of beam having an axial amplitude null and an azimuthal phase gradient. Radiation force examples obtained through numerical evaluation of the radiation force function are computed for an air bubble, a hexane, a red blood and mercury fluid spheres in water. The examples were selected to illustrate conditions having progressive, standing and quasi-standing waves with appropriate selection of the waves’ amplitude ratio. An especially noteworthy result is the lack of a specific vibrational mode contribution to the radiation force determined by appropriate selection of the HOBB parameters.
3. Air gasification of rice husk in bubbling fluidized bed reactor with bed heating by conventional charcoal.
PubMed
Makwana, J P; Joshi, Asim Kumar; Athawale, Gaurav; Singh, Dharminder; Mohanty, Pravakar
2015-02-01
An experimental study of air gasification of rice husk was conducted in a bench-scale fluidized bed gasifier (FBG) having 210 mm diameter and 1600 mm height. Heating of sand bed material was performed using conventional charcoal fuel. Different operating conditions like bed temperature, feeding rate and equivalence ratio (ER) varied in the range of 750-850 °C, 25-31.3 kg/h, and 0.3-0.38, respectively. Flow rate of air was kept constant (37 m(3)/h) during FBG experiments. The carbon conversion efficiencies (CCE), cold gas efficiency, and thermal efficiency were evaluated, where maximum CCE was found as 91%. By increasing ER, the carbon conversion efficiency was decreased. Drastic reduction in electric consumption for initial heating of gasifier bed with charcoal compared to ceramic heater was ∼45%. Hence rice husk is found as a potential candidate to use directly (without any processing) in FBG as an alternative renewable energy source from agricultural field. PMID:25446789
4. Airborne & SAR Synergy Reveals the 3D Structure of Air Bubble Entrainment in Internal Waves and Frontal Zones
da Silva, J. C. B.; Magalhaes, J. M.; Batista, M.; Gostiaux, L.; Gerkema, T.; New, A. L.
2013-03-01
Internal waves are now recognised as an important mixing mechanism in the ocean. Mixing at the base of the mixed layer and in the seasonal thermocline affects the properties of those water masses which define the exchange of heat and freshwater between the atmosphere and ocean. The breaking of Internal Solitary Waves (ISWs) contributes significantly to turbulent mixing in the near-surface layers, through the continual triggering of instabilities as they propagate and shoal towards the coast or shallow topography. Here we report some results of the EU funded project A.NEW (Airborne observations of Nonlinear Evolution of internal Waves generated by internal tidal beams). The airborne capabilities to observe small scale structure of breaking internal waves in the near-shore zone has been demonstrated in recent studies (e.g. Marmorino et al., 2008). In particular, sea surface thermal signatures of shoaling ISWs have revealed the turbulent character of these structures in the form of surface “boil” features. On the other hand, some in situ measurements of internal waves and theoretical work suggest subsurface entrainment of air bubbles in the convergence zones of ISWs (Serebryany and Galybin, 2009; Grimshaw et al., 2010). We conducted airborne remote sensing observations in the coastal zone off the west Iberian Peninsula (off Lisbon, Portugal) using high resolution imaging sensors: LiDAR (Light Detection And Ranging), hyperspectral cameras (Eagle and Hawk) and thermal infrared imaging (TABI-320). These measurements were planned based on previous SAR observations in the region, which included also near-real time SAR overpasses (ESA project AOPT-2423 and TerraSAR-X project OCE-0056). The airborne measurements were conducted from board the NERC (Natural Environmental Research Centre) Do 228 aircraft in the summer of 2010. The TABI-320 thermal airborne broadband imager can distinguish temperature differences as small as one-twentieth of a degree and operates in the
5. Shape Oscillations of Bubbles in Water Driven by Modulated Ultrasonic Radiation Pressure and Applications to Interfacial Dynamics
Asaki, Thomas James
1995-01-01
Acoustic levitation techniques were used for static and dynamic studies of single air bubbles in aqueous solutions. Bubble sizes ranged from 0.3 to 6 mm in radius. The static position of a bubble, determined by the balance between the buoyant and acoustic forces, agrees well with existing theory. Measured bubble aspect ratios are a nonmonotonic increasing function of bubble size and agree well with an improved expression based on the radiation stress tensor. Small amplitude normal mode shape oscillations were induced by modulation of the acoustic radiation pressure and were detected by optical pseudo-extinction and optical interferometry techniques. Driven oscillation frequencies for bubbles in clean water agree well with Lamb theory although significant frequency shifts occur for bubbles of large aspect ratio (_sp{~ }{>}1.3). An improved asymptotic expansion, important for bubbles in fluids and for liquid drops in air, was obtained for the complex free decay frequency. The free decay of quadrupole shape oscillations was measured for nearly spherical bubbles (aspect ratio ~ 1.01) in clean water, clean salt water, sea water, and in the presence of surfactants. Bubbles in clean solutions exhibit behavior indicative of an ideal clean interface. Frequency shifts and excess damping were observed for bubbles in sea water, in aqueous solutions of Triton X-100, and for a bubble coated with the insoluble surfactant stearic acid. The damping and frequency exhibit nonmonotonic behavior with respect to interfacial surfactant coverage; maxima occur at coverages which do not significantly affect the surface tension. At large coverages the damping is increased and the frequency is reduced relative to theoretical expectations for a clean ideal interface at constant surface tension. These results are in qualitative agreement with theories incorporating interfacial viscoelastic effects and with planar-surface capillary ripple experiments which also exhibit maxima in the damping as a
6. Interfacial Bubble Deformations
Seymour, Brian; Shabane, Parvis; Cypull, Olivia; Cheng, Shengfeng; Feitosa, Klebert
Soap bubbles floating at an air-water experience deformations as a result of surface tension and hydrostatic forces. In this experiment, we investigate the nature of such deformations by taking cross-sectional images of bubbles of different volumes. The results show that as their volume increases, bubbles transition from spherical to hemispherical shape. The deformation of the interface also changes with bubble volume with the capillary rise converging to the capillary length as volume increases. The profile of the top and bottom of the bubble and the capillary rise are completely determined by the volume and pressure differences. James Madison University Department of Physics and Astronomy, 4VA Consortium, Research Corporation for Advancement of Science.
7. Thermocapillary Flow and Aggregation of Bubbles on a Solid Wall
NASA Technical Reports Server (NTRS)
Kasumi, Hiroki; Solomentsev, Yuri E.; Guelcher, Scott A.; Anderson, John L.; Sides, Paul J.
2000-01-01
were equated by using a wall hindrance parameter q: U = qu [1] which shows the velocity of bubble is proportional to the entraining velocity. The hindrance parameter q can experimentally be measured independently. q can also be calculated by solving the equations of motion for a bubble translating parallel to a solid wall. The experimental cell is cylindrical with an ID of 10 cm and consists of a 1 cm deep main cell filled with silicone oil and flanked by two thermal reservoirs. The upper thermal reservoir was heated and the lower thermal reservoir was cooled so that the bubbles aggregate. Two types of silicone oil (eta = 0.02 and 0.50 Pa s) were used. Two equal sized air bubbles were injected into the cell with a syringe. The center-to-center distance of bubbles was observed through a microscope. Bubble radius ranged from 0.40 mm to 0.65 mm and the temperature gradients along with the cell ranged from 1400 to 5000 K/m. The bubbles aggregated when heat flows from the wall to the fluid. The velocities of bubbles were in the range of 1 - 10 microns/s. The separation r decreased more quickly when the temperature gradient was higher, bubble size was larger, and the oil viscosity was lower. r decreased more rapidly as the bubbles approached each other. Dimensionless time was arbitrarily set to be zero when the dimensionless center-to-center distance between the bubbles was 4. All the bubble trajectories fall onto one line, especially in the range of dimensionless distance from 4 to 3. This means the relative movement of the bubble pair is proportional to the temperature gradient and bubble size and it is inversely proportional to the viscosity of the oil. This result strongly suggests that the thermocapillary flow-based aggregation mechanism is correct. A value of q can be estimated by fitting the scaled data to Eq. [1]. A best fit value of q was obtained as q = 0.26 with a standard deviation of 0.03. Independent experimental results for q for a 0.5 mm radius bubble, give
8. Rheology of dense bubble suspensions
Kang, Sang-Yoon; Sangani, Ashok S.; Tsao, Heng-Kwong; Koch, Donald L.
1997-06-01
The rheological behavior of rapidly sheared bubble suspensions is examined through numerical simulations and kinetic theory. The limiting case of spherical bubbles at large Reynolds number Re and small Weber number We is examined in detail. Here, Re=ργa2/μ and We=ργ2a3/s, a being the bubble radius, γ the imposed shear, s the interfacial tension, and μ and ρ, respectively, the viscosity and density of the liquid. The bubbles are assumed to undergo elastic bounces when they come into contact; coalescence can be prevented in practice by addition of salt or surface-active impurities. The numerical simulations account for the interactions among bubbles which are assumed to be dominated by the potential flow of the liquid caused by the motion of the bubbles and the shear-induced collision of the bubbles. A kinetic theory based on Grad's moment method is used to predict the distribution function for the bubble velocities and the stress in the suspension. The hydrodynamic interactions are incorporated in this theory only through their influence on the virtual mass and viscous dissipation in the suspension. It is shown that this theory provides reasonable predictions for the bubble-phase pressure and viscosity determined from simulations including the detailed potential flow interactions. A striking result of this study is that the variance of the bubble velocity can become large compared with (γa)2 in the limit of large Reynolds number. This implies that the disperse-phase pressure and viscosity associated with the fluctuating motion of the bubbles is quite significant. To determine whether this prediction is reasonable even in the presence of nonlinear drag forces induced by bubble deformation, we perform simulations in which the bubbles are subject to an empirical drag law and show that the bubble velocity variance can be as large as 15γ2a2.
9. High-speed photography of the bubble generated by an airgun
SciTech Connect
Langhammer, J.; Landroe, M.
1996-01-01
High-speed photography has been used visually to study the shape, surface, turbulence and behavior of an underwater oscillating bubble generated by an airgun. The source wa a BOLT airgun with a chamber volume of 1.6 cu.in., placed in a 0.85 m{sup 3} tank at 0.5 m depth. Near-field signatures were also recorded in order to compare the instant photographs of the oscillating bubble with the pressure field recorded about 25 cm from the gun. Estimations of the bubble-wall velocity and bubble radius estimated from high-speed film sequences are also presented, and are compared with modeled results. The deviation between the modeled and measured bubble radii was at most 9%. In order to check the capacity for transmission of light through the bubble, a concentrated laser beam was used as illumination. The authors found that the air bubble is a strong scattering medium of laser light, hence the bubble is opaque.
10. Oscillating bubble concentration and its size distribution using acoustic emission spectra.
PubMed
Avvaru, Balasubrahmanyam; Pandit, Aniruddha B
2009-01-01
New method has been proposed for the estimation of size and number density distribution of oscillating bubbles in a sonochemical reactor using acoustic emission spectra measurements. Bubble size distribution has been determined using Minnaert's equation [M. Minnaert, On musical air bubbles and sound of running water, Philanthr. Mag. 16 (1933) 235], i.e., size of oscillating bubble is inversely related to the frequency of its volume oscillations. Decomposition of the pressure signal measured by the hydrophone in frequency domain of FFT spectrum and then inverse FFT reconstruction of the signal at each frequency level has been carried out to get the information about each of the bubble/cavity oscillation event. The number mean radius of the bubble size is calculated to be in the range of 50-80 microm and it was not found to vary much with the spatial distribution of acoustic field strength of the ultrasound processor used in the work. However, the number density of the oscillating bubbles and the nature of the distribution were found to vary in different horizontal planes away from the driving transducer surface in the ultrasonic bath. A separate set of experiments on erosion assessment studies were carried out using a thin aluminium foil, revealing a phenomena of active region of oscillating bubbles at antinodal points of the stationary waves, identical to the information provided by the acoustic emission spectra at the same location in the ultrasonic bath. PMID:18752981
11. The formation of soap bubbles created by blowing on soap films
Salkin, Louis; Schmit, Alexandre; Panizza, Pascal; Courbin, Laurent
2015-11-01
Using either circular bubble wands or long-lasting vertically falling soap films having an adjustable steady state thickness, we study the formation of soap bubbles created when air is blown through a nozzle onto a soap film. We vary nozzle radius, film size, space between the film and nozzle, and gas density, and we measure the gas velocity threshold above which bubbles are generated. The response is sensitive to confinement, that is, the ratio between film and jet sizes, and dissipation in the turbulent gas jet which is a function of the distance from the nozzle to the film. We observe four different regimes that we rationalize by comparing the dynamic pressure of a jet on the film and the Laplace pressure needed to create the curved surface of a bubble.
12. Azimuthal asymmetries and vibrational modes in bubble pinch-off
Schmidt, Laura E.
The pressure-driven inertial collapse of a cylindrical void in an inviscid liquid is an integrable, Hamiltonian system that forms a finite-time singularity as the radius of the void collapses to zero. Here it is shown that when the natural cylindrical symmetry of the void is perturbed azimuthally, the perturbation modes neither grow nor decay, but instead cause constant amplitude vibrations about the leading-order symmetric collapse. Though the amplitudes are frozen in time, they grow relative to the mean radius which is collapsing to zero, eventually overtaking the leading-order symmetric implosion. Including weak viscous dissipation destroys the integrability of the underlying symmetric implosion, and the effect on the stability spectrum is that short-wavelength disturbances are now erased as the implosion proceeds. Introducing a weak rotational flow component to the symmetric implosion dynamics causes the vibrating shapes to spin as the mean radius collapses. The above theoretical scenario is compared to a closely related experimental realization of void implosion: the disconnection of an air bubble from an underwater nozzle. There, the thin neck connecting the bubble to the nozzle implodes primarily radially inward and disconnects. Recent experiments were able to induce vibrations of the neck shape by releasing the bubble from a slot-shaped nozzle. The frequency and amplitude of the observed vibrations are consistent with the theoretical prediction once surface tension effects are taken into account.
13. Bubble dielectrophoresis
NASA Technical Reports Server (NTRS)
Jones, T. B.; Bliss, G. W.
1977-01-01
The theoretical principles related to bubble dielectrophoresis are examined, taking into account the polarization force, aspects of bubble deformation, the electrostatic bubble levitation theorem, and the equation of motion. The measurement of the dielectrophoretic force on static and dynamic bubbles represents a convenient experimental method for the study of the general problem of dielectrophoresis. The experiments reported include static-force measurements, static-levitation experiments, and dynamic-force measurements.
14. Partial coalescence of soap bubbles
Harris, Daniel M.; Pucci, Giuseppe; Bush, John W. M.
2015-11-01
We present the results of an experimental investigation of the merger of a soap bubble with a planar soap film. When gently deposited onto a horizontal film, a bubble may interact with the underlying film in such a way as to decrease in size, leaving behind a smaller daughter bubble with approximately half the radius of its progenitor. The process repeats up to three times, with each partial coalescence event occurring over a time scale comparable to the inertial-capillary time. Our results are compared to the recent numerical simulations of Martin and Blanchette and to the coalescence cascade of droplets on a fluid bath.
15. Recalcitrant bubbles
PubMed Central
Shanahan, Martin E. R.; Sefiane, Khellil
2014-01-01
We demonstrate that thermocapillary forces may drive bubbles against liquid flow in ‘anomalous' mixtures. Unlike ‘ordinary' liquids, in which bubbles migrate towards higher temperatures, we have observed vapour bubbles migrating towards lower temperatures, therefore against the flow. This unusual behaviour may be explained by the temperature dependence of surface tension of these binary mixtures. Bubbles migrating towards their equilibrium position follow an exponential trend. They finally settle in a stationary position just ‘downstream' of the minimum in surface tension. The exponential trend for bubbles in ‘anomalous' mixtures and the linear trend in pure liquids can be explained by a simple model. For larger bubbles, oscillations were observed. These oscillations can be reasonably explained by including an inertial term in the equation of motion (neglected for smaller bubbles). PMID:24740256
16. Generating Soap Bubbles by Blowing on Soap Films.
PubMed
Salkin, Louis; Schmit, Alexandre; Panizza, Pascal; Courbin, Laurent
2016-02-19
Making soap bubbles by blowing air on a soap film is an enjoyable activity, yet a poorly understood phenomenon. Working either with circular bubble wands or long-lived vertical soap films having an adjustable steady state thickness, we investigate the formation of such bubbles when a gas is blown through a nozzle onto a film. We vary film size, nozzle radius, space between the film and nozzle, and gas density, and we measure the gas velocity threshold above which bubbles are formed. The response is sensitive to containment, i.e., the ratio between film and jet sizes, and dissipation in the turbulent gas jet, which is a function of the distance from the film to the nozzle. We rationalize the observed four different regimes by comparing the dynamic pressure exerted by the jet on the film and the Laplace pressure needed to create the curved surface of a bubble. This simple model allows us to account for the interplay between hydrodynamic, physicochemical, and geometrical factors. PMID:26943558
17. Generating Soap Bubbles by Blowing on Soap Films
Salkin, Louis; Schmit, Alexandre; Panizza, Pascal; Courbin, Laurent
2016-02-01
Making soap bubbles by blowing air on a soap film is an enjoyable activity, yet a poorly understood phenomenon. Working either with circular bubble wands or long-lived vertical soap films having an adjustable steady state thickness, we investigate the formation of such bubbles when a gas is blown through a nozzle onto a film. We vary film size, nozzle radius, space between the film and nozzle, and gas density, and we measure the gas velocity threshold above which bubbles are formed. The response is sensitive to containment, i.e., the ratio between film and jet sizes, and dissipation in the turbulent gas jet, which is a function of the distance from the film to the nozzle. We rationalize the observed four different regimes by comparing the dynamic pressure exerted by the jet on the film and the Laplace pressure needed to create the curved surface of a bubble. This simple model allows us to account for the interplay between hydrodynamic, physicochemical, and geometrical factors.
18. Wetting of soap bubbles on hydrophilic, hydrophobic, and superhydrophobic surfaces
Arscott, Steve
2013-06-01
Wetting of sessile bubbles on various wetting surfaces (solid and liquid) has been studied. A model is presented for the apparent contact angle of a sessile bubble based on a modified Young's equation--the experimental results agree with the model. Wetting a hydrophilic surface results in a bubble contact angle of 90° whereas using a superhydrophobic surface one observes 134°. For hydrophilic surfaces, the bubble angle diminishes with bubble radius whereas on a superhydrophobic surface, the bubble angle increases. The size of the plateau borders governs the bubble contact angle, depending on the wetting of the surface.
19. Microfluidic pinball made of quasi-2D microbubbles: on the collective dynamics of confined bubbles pulsating under ultrasound
Mekki-Berrada, Flore; Thibault, Pierre; Marmottant, Philippe
2014-11-01
The pulsation properties of air bubbles under ultrasound have received much attention since the development of sonoporation and contrast agents. Spherical bubbles are well known to induce streaming when excited by ultrasound. Here we study how the vibration of very confined bubbles pinned to pits (assuming a quasi-2D pancake'' shape) influences the streaming inside a microfluidic channel. For a single bubble, 20 to 70 μm in radius, we observe the well-known parametric instability, giving rise to a shape deformation, and sketch a phase diagram of existence of the surface modes. We also evidence very active out-of-plane fluid circulations located near the bubble that are correlated with the surface modes. In the case of a bubble pair, the interaction results in an additional bipolar surface mode. We demonstrate that a long-range multipolar recirculating flow occurs from a combination of phase-lagged vibration modes. Using a large triangular lattice of these microbubbles, we obtain a unique acoustic bubble pinball'' driving fluid and particles in complex paths, the constructive interference between vibration modes leading to the elaborate in-plane microstreaming vortices. This work gives a new insight in bubbles efficiency to trigger local and non-local mixing in laminar flows.
NASA Technical Reports Server (NTRS)
Harris, Michael R.
1987-01-01
Resonator configurations permitting operation with large mode radius while maintaining good transverse mode discrimination are considered. Stable resonators incorporating an intracavity telescope and unstable resonator geometries utilizing an output coupler with a Gaussian reflectivity profile are shown to enable large radius single mode laser operation. Results of heterodyne studies of pulsed CO2 lasers with large (11mm e sup-2 radius) fundamental mode sizes are presented demonstrating minimal frequency sweeping in accordance with the theory of laser-induced medium perturbations.
1. Partial coalescence of soap bubbles
Pucci, G.; Harris, D. M.; Bush, J. W. M.
2015-06-01
We present the results of an experimental investigation of the merger of a soap bubble with a planar soap film. When gently deposited onto a horizontal film, a bubble may interact with the underlying film in such a way as to decrease in size, leaving behind a smaller daughter bubble with approximately half the radius of its progenitor. The process repeats up to three times, with each partial coalescence event occurring over a time scale comparable to the inertial-capillary time. Our results are compared to the recent numerical simulations of Martin and Blanchette ["Simulations of surfactant effects on the dynamics of coalescing drops and bubbles," Phys. Fluids 27, 012103 (2015)] and to the coalescence cascade of droplets on a fluid bath.
2. Bubble, Bubble, Toil and Trouble.
ERIC Educational Resources Information Center
Journal of Chemical Education, 2001
2001-01-01
Bubbles are a fun way to introduce the concepts of surface tension, intermolecular forces, and the use of surfactants. Presents two activities in which students add chemicals to liquid dishwashing detergent with water in order to create longer lasting bubbles. (ASK)
3. Studies on pressure response of gas bubbles contributions of condensed droplets in bubbles generated by a uniform nucleation
NASA Technical Reports Server (NTRS)
Matsumoto, Y.
1988-01-01
The response of a tiny gas bubble under reduced pressure is investigated in its relation to cavitation. Equations of motion are formulated for gas mixtures inside the bubble and numerical calculations performed for several examples. The conclusions are as follows: (1) at the onset of bubble growth, the gas mixture inside it adiabatically expands and the temperature decreases. Condensed droplets appear inside the gas mixture due to a uniform nucleation and the temperature recovers, thus the motion of the bubble is apparently isothermal; (2) the evaporation and condensation coefficient largely affects bubble motions (maximum radius, period and rate of attenuation of the bubble oscillation) including the uniform contraction; (3) the oscillation period of the bubble is longer as the equilibrium bubble radius is larger when the surrounding pressure decreases stepwise. In this circumstance the temperature inside the bubble is kept constant due to condensation evaporation phenomena and is nearly isothermal; and (4) when the surrounding pressure decreases in a stepwise fashion, the critical pressure bubble radius relation becomes closer to that for the isothermal process if the bubble radius is larger than 8 microns.
4. Computational Analysis for Secondary Vorticity and Non-Axisymmetric Features in the Shock-Bubble Interaction
Niederhaus, John; Ranjan, Devesh; Motl, Bradley; Oakley, Jason; Anderson, Mark; Bonazza, Riccardo; Greenough, Jeffrey
2006-11-01
Computations for the shock-bubble interaction are performed using the 3D Eulerian AMR code Raptor. In the simulations, performed in 3D at a fine-grid resolution of 128 grid points per bubble radius, a planar shock wave of specified strength accelerates a spherical gas bubble embedded in an otherwise uniform air or nitrogen medium. The computed solutions clearly resolve the development of distinctive features observed in previous experiments (Haas and Sturtevant, J. Fluid. Mech., 1987) and simulations (Zabusky and Zeng, J. Fluid. Mech., 1998), including jets, secondary shocks, vortex rings, and turbulent mixing. Using both flow visualizations and quantitative diagnostics, the non-axisymmetric and turbulent features developing in the flow are characterized. Local fluctuating quantities are defined with respect to an azimuthal mean, and mechanisms are identified for the post-shock origin and growth of secondary vortices and turbulent features.
5. Bubble migration during hydrate formation
Shagapov, V. Sh.; Chiglintseva, A. S.; Rusinov, A. A.
2015-03-01
A model of the process of migration of methane bubbles in water under thermobaric conditions of hydrate formation is proposed. The peculiarities of the temperature field evolution, migration rate, and changes in the radius and volume fraction of gas hydrate bubbles are studied. It is shown that, with a constant mass flow of gas from the reservoir bottom, for all parameters of the surfacing gas hydrate disperse system, there is a quasistationary pattern in the form of a "step"-like wave. Depending on the relationship of the initial gas bubble density with the average gas density in the hydrate composition determined by the depth from which bubbles rise to the surface, the final radius of hydrate particles may be larger or smaller than the initial gas bubble radii. It is established that the speed at which gas hydrate inclusions rise to the surface decreases by several times due to an increase in their weight during hydrate formation. The influence of the depth of the water reservoir whose bottom is a gas flow source on the dynamics of hydrate formation is studied.
6. The Dueling Bubble Experiment
Roy, Anshuman; Borrell, Marcos; Felts, John; Leal, Gary; Hirsa, Amir
2007-11-01
When two drops or bubbles are brought into close proximity to each other, the thin film of the fluid between them drains as they are squeezed together. If the film becomes thin enough that intermolecular forces of attraction overwhelm capillary forces, the drops/bubbles coalesce and the time it takes for this to happen, starting from the point of apparent contact is referred to as the drainage time. One practical version of this scenario occurs during the formation of foams, when the thin film forms between gas bubbles that are growing in volume with time. We performed an experimental study that is intended to mimic this process in which the two drops (or bubbles) in the size range of 50-100 microns diameter are created by oozing a liquid/gas out of two capillaries of diameter less than 100 microns directly facing each other and immersed in a second fluid. We present measurements of drainage times for the cases of very low viscosity ratios PDMS drops in Castor oil (less than 0.05) and bubbles of air in PDMS, and highlight the differences that arise in part due to the different boundary conditions for thin film drainage for liquid-liquid versus gas-liquid systems, and in part due to the different Hamaker constants for the two systems.
7. Bubble diagnostics
DOEpatents
Visuri, Steven R.; Mammini, Beth M.; Da Silva, Luiz B.; Celliers, Peter M.
2003-01-01
The present invention is intended as a means of diagnosing the presence of a gas bubble and incorporating the information into a feedback system for opto-acoustic thrombolysis. In opto-acoustic thrombolysis, pulsed laser radiation at ultrasonic frequencies is delivered intraluminally down an optical fiber and directed toward a thrombus or otherwise occluded vessel. Dissolution of the occlusion is therefore mediated through ultrasonic action of propagating pressure or shock waves. A vapor bubble in the fluid surrounding the occlusion may form as a result of laser irradiation. This vapor bubble may be used to directly disrupt the occlusion or as a means of producing a pressure wave. It is desirable to detect the formation and follow the lifetime of the vapor bubble. Knowledge of the bubble formation and lifetime yields critical information as to the maximum size of the bubble, density of the absorbed radiation, and properties of the absorbing material. This information can then be used in a feedback system to alter the irradiation conditions.
8. Interactions of multiple spark-generated bubbles with phase differences
Fong, Siew Wan; Adhikari, Deepak; Klaseboer, Evert; Khoo, Boo Cheong
2009-04-01
This paper aims to study the complex interaction between multiple bubbles, and to provide a summary and physical explanation of the phenomena observed during the interaction of two bubbles. High-speed photography is utilized to observe the experiments involving multiple spark-generated bubbles. Numerical simulations corresponding to the experiments are performed using the Boundary Element Method (BEM). The bubbles are typically between 3 and 5 mm in radius and are generated either in-phase (at the same time) or with phase differences. Complex phenomena are observed such as bubble splitting, and high-speed jetting inside a bubble caused by another collapsing bubble nearby (termed the ‘catapult’ effect). The two-bubble interactions are broadly classified in a graph according to two parameters: the relative inter-bubble distance and the phase difference (a new parameter introduced). The BEM simulations provide insight into the physics, such as bubble shape changes in detail, and jet velocities. Also presented in this paper are the experimental results of three bubble interactions. The interesting and complex observations of multiple bubble interaction are important for a better understanding of real life applications in medical ultrasonic treatment and ultrasonic cleaning. Many of the three bubble interactions can be explained by isolating bubble pairs and classifying their interaction according to the graph for the two bubble case. This graph can be a useful tool to predict the behavior of multiple bubble interactions.
Downie, E. J.
2016-03-01
The proton radius puzzle is the difference between the proton radius as measured with electron scattering and in the excitation spectrum of atomic hydrogen, and that measured with muonic hydrogen spectroscopy. Since the inception of the proton radius puzzle in 2010 by the measurement of Pohl et al.[1], many possible resolutions to the puzzle have been postulated, but, to date, none has been generally accepted. New data are therefore necessary to resolve the issue. We briefly review the puzzle, the proposed solutions, and the new electron scattering and spectroscopy experiments planned and underway. We then introduce the MUSE experiment, which seeks to resolve the puzzle by simultaneously measuring elastic electron and muon scattering on the proton, in both charge states, thereby providing new information to the puzzle. MUSE addresses issues of two-photon effects, lepton universality and, possibly, new physics, while providing simultaneous form factor, and therefore radius, measurements with both muons and electrons.
10. Oscillations of soap bubbles
Kornek, U.; Müller, F.; Harth, K.; Hahn, A.; Ganesan, S.; Tobiska, L.; Stannarius, R.
2010-07-01
Oscillations of droplets or bubbles of a confined fluid in a fluid environment are found in various situations in everyday life, in technological processing and in natural phenomena on different length scales. Air bubbles in liquids or liquid droplets in air are well-known examples. Soap bubbles represent a particularly simple, beautiful and attractive system to study the dynamics of a closed gas volume embedded in the same or a different gas. Their dynamics is governed by the densities and viscosities of the gases and by the film tension. Dynamic equations describing their oscillations under simplifying assumptions have been well known since the beginning of the 20th century. Both analytical description and numerical modeling have made considerable progress since then, but quantitative experiments have been lacking so far. On the other hand, a soap bubble represents an easily manageable paradigm for the study of oscillations of fluid spheres. We use a technique to create axisymmetric initial non-equilibrium states, and we observe damped oscillations into equilibrium by means of a fast video camera. Symmetries of the oscillations, frequencies and damping rates of the eigenmodes as well as the coupling of modes are analyzed. They are compared to analytical models from the literature and to numerical calculations from the literature and this work.
11. Adsorption of egg phosphatidylcholine to an air/water and triolein/water bubble interface: use of the 2-dimensional phase rule to estimate the surface composition of a phospholipid/triolein/water surface as a function of surface pressure.
PubMed
Mitsche, Matthew A; Wang, Libo; Small, Donald M
2010-03-11
Phospholipid monolayers play a critical role in the structure and stabilization of biological interfaces, including all membranes, the alveoli of the lungs, fat droplets in adipose tissue, and lipoproteins. The behavior of phospholipids in bilayers and at an air-water interface is well understood. However, the study of phospholipids at oil-water interfaces is limited due to technical challenges. In this study, egg phosphatidylcholine (EPC) was deposited from small unilamellar vesicles onto a bubble of either air or triolein (TO) formed in a low-salt buffer. The surface tension (gamma) was measured using a drop tensiometer. We observed that EPC binds irreversibly to both interfaces and at equilibrium exerts approximately 12 and 15 mN/m of pressure (Pi) at an air and TO interface, respectively. After EPC was bound to the interface, the unbound EPC was washed out of the cuvette, and the surface was compressed to study the Pi/area relationship. To determine the surface concentration (Gamma), which cannot be measured directly, compression isotherms from a Langmuir trough and drop tensiometer were compared. The air-water interfaces had identical characteristics using both techniques; thus, Gamma on the bubble can be determined by overlaying the two isotherms. Both TO and EPC are surface-active, so in a mixed TO/EPC monolayer, both molecules will be exposed to water. Since TO is less surface-active than EPC, as Pi increases, the TO is progressively ejected. To understand the Pi/area isotherm of EPC on a TO bubble, a variety of TO-EPC mixtures were spread at the air-water interface. The isotherms show an abrupt break in the curve caused by the ejection of TO from the monolayer into a new bulk phase. By overlaying the compression isotherm above the ejection point with a TO bubble compression isotherm, Gamma can be estimated. This allows determination of Gamma of EPC on a TO bubble as a function of Pi. PMID:20151713
12. Motion of a bubble ring in a viscous fluid
Cheng, M.; Lou, J.; Lim, T. T.
2013-06-01
In this paper, lattice Boltzmann method was undertaken to study the dynamics of a vortex ring bubble (or bubble ring) in a viscous incompressible fluid. The study is motivated partly by our desire to assess whether a bubble ring keeps increasing its radius and decreasing its rise velocity as it rises through fluid as was predicted by Turner ["Buoyant vortex rings," Proc. R. Soc. London, Ser. A 239, 61 (1957)], 10.1098/rspa.1957.0022 and Pedley ["The toroidal bubble," J. Fluid Mech. 32, 97 (1968)], 10.1017/S0022112068000601, or does the ring like a rising bubble, eventually reaches a steady state where its radius and velocity remain constant as was predicted by Joseph et al. [Potential Flows of Viscous and Viscoelastic Fluids (Cambridge University Press, 2008)]. The parameters investigated included ring circulation, Reynolds number, density ratio and Bond number. Our numerical results show that a rising bubble ring increases its radius and decreases its velocity, but the process is interrupted by ring instability that eventually causes it to break up into smaller bubbles. This finding is consistent with the stability analysis by Pedley, who predicted that a bubble ring has a finite lifespan and is ultimately destroyed by surface tension instability. Furthermore, it is found that increasing initial circulation has a stabilizing effect on a bubble ring while increasing Reynolds number or Bond number hastens ring instability, resulting in an earlier break up into smaller bubbles; the number of bubbles depends on the wavenumber of the perturbation.
13. Robust acoustic wave manipulation of bubbly liquids
Gumerov, N. A.; Akhatov, I. S.; Ohl, C.-D.; Sametov, S. P.; Khazimullin, M. V.; Gonzalez-Avila, S. R.
2016-03-01
Experiments with water-air bubbly liquids when exposed to acoustic fields of frequency ˜100 kHz and intensity below the cavitation threshold demonstrate that bubbles ˜30 μm in diameter can be "pushed" away from acoustic sources by acoustic radiation independently from the direction of gravity. This manifests formation and propagation of acoustically induced transparency waves (waves of the bubble volume fraction). In fact, this is a collective effect of bubbles, which can be described by a mathematical model of bubble self-organization in acoustic fields that matches well with our experiments.
14. Mechanism of bubble detachment from vibrating walls
SciTech Connect
Kim, Dongjun; Park, Jun Kwon Kang, Kwan Hyoung; Kang, In Seok
2013-11-15
We discovered a previously unobserved mechanism by which air bubbles detach from vibrating walls in glasses containing water. Chaotic oscillation and subsequent water jets appeared when a wall vibrated at greater than a critical level. Wave forms were developed at water-air interface of the bubble by the wall vibration, and water jets were formed when sufficiently grown wave-curvatures were collapsing. Droplets were pinched off from the tip of jets and fell to the surface of the glass. When the solid-air interface at the bubble-wall attachment point was completely covered with water, the bubble detached from the wall. The water jets were mainly generated by subharmonic waves and were generated most vigorously when the wall vibrated at the volume resonant frequency of the bubble. Bubbles of specific size can be removed by adjusting the frequency of the wall's vibration.
15. Breaking waves and near-surface sea spray aerosol dependence on changing winds: Wave breaking efficiency and bubble-related air-sea interaction processes
Hwang, P. A.; Savelyev, I. B.; Anguelova, M. D.
2016-05-01
Simultaneous measurements of sea spray aerosol (SSA), wind, wave, and microwave brightness temperature are obtained in the open ocean on-board Floating Instrument Platform (FLIP). These data are analysed to clarify the ocean surface processes important to SSA production. Parameters are formulated to represent surface processes with characteristic length scales spanning a broad range. The investigation reveals distinct differences of the SSA properties in rising winds and falling winds, with higher SSA volume in falling winds. Also, in closely related measurements of whitecap coverage, higher whitecap fraction as a function of wind speed is found in falling winds than in rising winds or in older seas than in younger seas. Similar trend is found in the short scale roughness reflected in the microwave brightness temperature data. In the research of length and velocity scales of breaking waves, it has been observed that the length scale of wave breaking is shorter in mixed seas than in wind seas. For example, source function analysis of short surface waves shows that the characteristic length scale of the dissipation function shifts toward higher wavenumber (shorter wavelength) in mixed seas than in wind seas. Similarly, results from feature tracking or Doppler analysis of microwave radar sea spikes, which are closely associated with breaking waves, show that the magnitude of the average breaking wave velocity is smaller in mixed seas than in wind seas. Furthermore, breaking waves are observed to possess geometric similarity. Applying the results of breaking wave analyses to the SSA and whitecap observations described above, it is suggestive that larger air cavities resulting from the longer breakers are entrained in rising high winds. The larger air cavities escape rapidly due to buoyancy before they can be fully broken down into small bubbles for the subsequent SSA production or whitecap manifestation. In contrast, in falling winds (with mixed seas more likely), the
16. Determining Flow Type and Shear Rate in Magmas From Bubble Shapes and Orientations
Rust, A. C.; Manga, M.; Cashman, K. V.
2001-12-01
To compare bubble geometries in obsidian to bubbles deformed under known conditions, we measure the deformation of air bubbles in corn syrup in simple shear. We use these experimental data and results of theoretical, numerical and experimental studies to interpret the shear environments that formed the textures preserved in obsidian samples. In particular, we use the shapes and orientations of bubbles in obsidian to estimate shear rates and assess flow type (simple vs. pure shear). This technique can be used to determine shear rates in volcanic conduits, the origin of pyroclastic obsidian, and the emplacement history and dynamics of obsidian flows. The deformation of a bubble is governed by the competing stresses from shearing that deforms, and surface tension that rerounds. The ratio of these stresses is the capillary number, Ca. An initially spherical bubble placed in a low Reynolds number, steady flow field deforms with a time-dependent shape and orientation until it reaches a steady geometry or breaks into smaller bubbles. A useful measure of the magnitude of flow-induced bubble deformation is the dimensionless parameter, D=(l-b)/(l+b) where l and b are the semi-major and semi-minor axes of the sheared bubble. For small deformations (Ca<< 1), low Reynolds number flow and bubble viscosity << suspending fluid viscosity, D ~ 2 Ca in pure shear and D ~ Ca in simple shear. In pure shear flow, bubble elongations are parallel to the shear direction regardless of the magnitude of bubble deformation. However, in simple shear flow, the angle between the bubble elongation and the flow varies with Ca, which is proportional to bubble radius and shear rate. Because the relationships between Ca and bubble orientation and shape for pure and simple shear differ, we can distinguish between these flow types using bubble geometries preserved in obsidian. Furthermore, because Ca is a function of shear rate, we can use relationships between Ca and D to calculate shear rates when
17. Experimental study on interaction and coalescence of synchronized multiple bubbles
Cui, P.; Wang, Q. X.; Wang, S. P.; Zhang, A. M.
2016-01-01
Experiments are carried out on the interaction and coalescence of two, three, and four bubbles with approximately the same sizes, distributed evenly and symmetrically. The bubbles are generated simultaneously by electric discharges, using an in-house designed series circuit, and their interaction is captured using a high-speed camera. Particular attentions are paid to if/when coalescence of bubbles happens and the motion of the joined bubbles. Some new features are observed, which depend mainly on the dimensionless distance γbb = dbb/Rmax, where dbb is the inter-bubble distance and Rmax is the maximum bubble radius. For γbb > 2, a jet forms and penetrates each side bubble, directed to the center of the configuration, resulting in a protrusion. Towards the end of collapse, a large portion of bubble gases is compressed into the protrusion from the main part of the toroidal bubble. For γbb < 2, the bubbles coalesce during expansion, and the part of the joined bubble's surface distal from the center of the configuration collapses faster than elsewhere. The experiments show that the oscillation period of multi-bubbles does not change appreciably without coalescence but increases significantly with coalescence. For three bubbles initiated at collinear positions with γbb > 2, the jets that form from the side bubbles are towards the middle, and the middle bubble splits into two parts, moving towards the two side bubbles. For γbb < 2, the side bubbles merge with the middle bubble during expansion, forming an ellipsoid bubble; the joined bubble collapses predominantly from two sides, where two inward jets form towards the end of collapse.
18. Effect of pressure on statics, dynamics, and stability of multielectron bubbles.
PubMed
Tempere, J; Silvera, I F; Devreese, J T
2001-12-31
The effect of positive and negative pressure on the modes of oscillation of a multielectron bubble in liquid helium is calculated. Already at low pressures of the order of 10-100 mbar, these effects are found to significantly modify the frequencies of oscillation of the bubble. Stabilization of the bubble is shown to occur in the presence of a small negative pressure, which expands the bubble radius. Above a threshold negative pressure, the bubble is unstable. PMID:11800888
19. Energy spectra in bubbly turbulence
Luther, Stefan; van den Berg, Thomas H.; Rensen, Judith; Lohse, Detlef
2004-11-01
The energy spectrum of single phase turbulent flow - apart from intermittency corrections - has been known since Kolomogorov 1941, E(k) ∝ k-5/3. How do bubbles modify this spectrum? To answer this question, we inject micro bubbles (radius 100 μm) in fully turbulent flow (Re_λ=200) up to volume concentrations of 0.3 %. Energy spectra and velocity structure functions are measured with hot-film anemometry. Under our experimental conditions, we find an enhancement of energy on small scales confirming numerical predictions by Mazzitelli, Lohse, and Toschi [Phys. Fluids 15, L5 (2003)]. They propose a mechanism in which bubbles are clustering most likely in downflow regions. This clustering is a lift force effect suppressing large vortical structures, while enhancing energy input on small scales.
20. Dynamics of Vapour Bubbles in Nucleate Boiling. 2; Evolution of Thermally Controlled Bubbles
NASA Technical Reports Server (NTRS)
Buyevich, Yu A.; Webbon, Bruce W.; Callaway, Robert (Technical Monitor)
1995-01-01
The previously developed dynamic theory of growth and detachment of vapour bubbles under conditions of nucleate pool boiling is applied to study motion and deformation of a bubble evolving at a single nucleation site. The bubble growth is presumed to be thermally controlled, and two components of heat transfer to the bubble are accounted of: the one from the bulk of surrounding liquid and the one due to heat conduction across a liquid microlayer formed underneath the bubble. Bubble evolution is governed by the buoyancy and an effective surface tension force, both the forces making the bubble centre of mass move away from the wall and, thus, assisting its detachment. Buoyancy-controlled and surface-tension-controlled regimes are considered separately in a meticulous way. The duration of the whole process of bubble evolution till detachment, the rate of growth, and the bubble departure size are found as functions of time and physical and operating parameters. Some repeatedly observed phenomena, such as an influence of gravity on the growth rate, are explained. Inferences of the model agree qualitatively with available experimental evidence, and conclusions pertaining to the dependence on gravity of the bubble radius at detachment and the whole time of the bubble development when being attached to the wall are confirmed quantitatively.
1. Magma mixing enhanced by bubble segregation
Wiesmaier, S.; Daniele, M.; Renggli, C.; Perugini, D.; De Campos, C.; Hess, K. U.; Ertel-Ingrisch, W.; Lavallée, Y.; Dingwell, D. B.
2014-12-01
Rising bubbles may significantly affect magma mixing paths as has been demonstrated by analogue experiments in the past. Here, bubble-advection experiments are performed for the first time employing natural materials at magmatic temperatures. Cylinders of basaltic glass were placed below cylinders of rhyolite glass. Upon melting, interstitial air formed bubbles that rose into the rhyolite melt, thereby entraining tails of basaltic liquid. The formation of plume-like filaments of advected basalt within the rhyolite was characterized by microCT and subsequent high-resolution EMP analyses. Melt entrainment by bubble ascent appears as efficient mechanism to mingle contrasting melt compositions. MicroCT imaging shows bubbles trailing each other and trails of multiple bubbles having converged. Rheological modelling of the filaments yields viscosities of up to 2 orders of magnitude lower than for the surrounding rhyolitic liquid. Such a viscosity contrast implies that subsequent bubbles rising are likely to follow the same pathways that previously ascending bubbles have generated. Filaments formed by multiple bubbles would thus experience episodic replenishment with mafic material. Fundamental implications for the concept of bubble advection in magma mixing are thus a) an acceleration of mixing because of decreased viscous resistance for bubbles inside filaments and b) non-conventional diffusion systematics because of intermittent supply of mafic material (instead of a single pulse) inside a filament. Inside these filaments, the mafic material was variably hybridised to andesitic through rhyolitic composition. Compositional profiles alone are ambiguous, however, to determine whether single or multiple bubbles were involved during formation of a filament. Statistical analysis, employing concentration variance as measure of homogenisation, demonstrates that also filaments appearing as single-bubble filaments are likely to have experienced multiple bubbles passing through
2. Tiny Bubbles.
ERIC Educational Resources Information Center
Kim, Hy
1985-01-01
A simple oxygen-collecting device (easily constructed from glass jars and a lid) can show bubbles released by water plants during photosynthesis. Suggestions are given for: (1) testing the collected gas; (2) using various carbon dioxide sources; and (3) measuring respiration. (DH)
3. Leverage bubble
Yan, Wanfeng; Woodard, Ryan; Sornette, Didier
2012-01-01
Leverage is strongly related to liquidity in a market and lack of liquidity is considered a cause and/or consequence of the recent financial crisis. A repurchase agreement is a financial instrument where a security is sold simultaneously with an agreement to buy it back at a later date. Repurchase agreement (repo) market size is a very important element in calculating the overall leverage in a financial market. Therefore, studying the behavior of repo market size can help to understand a process that can contribute to the birth of a financial crisis. We hypothesize that herding behavior among large investors led to massive over-leveraging through the use of repos, resulting in a bubble (built up over the previous years) and subsequent crash in this market in early 2008. We use the Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles and behavioral finance to study the dynamics of the repo market that led to the crash. The JLS model qualifies a bubble by the presence of characteristic patterns in the price dynamics, called log-periodic power law (LPPL) behavior. We show that there was significant LPPL behavior in the market before that crash and that the predicted range of times predicted by the model for the end of the bubble is consistent with the observations.
4. Nano bubbles in liquid of a noble-gas mixture.
PubMed
Yamamoto, Takenori; Ohnishi, Shuhei
2010-02-01
Large-scale molecular dynamics (MD) simulations with over one million atoms are used to investigate nano bubbles in Ar-Ne liquid. The simulations demonstrate cavitations in the stretched liquid, and bubble creation and collapse. We find that a small cavity created in the stretched liquid spontaneously transforms into a nano bubble with the homogeneous vapor region. The equilibrium spherical bubble of 11.4 nm in radius is obtained after the long-time MD run. The surface tension of the nano bubble is found to be larger than that of the flat surface. PMID:20094667
5. Physical conditions for trapping air by a microtrichia-covered insect cuticle during temporary submersion
Neumann, Dietrich; Woermann, Dietrich
2009-08-01
The intertidal midge Clunio, which reproduces on exposed rocky seashores, becomes enclosed in an irregularly shaped air bubble during short submersion by incoming waves. This water-repellent property of Clunio’s cuticle is caused by a complete cover of hydrophobic microtrichia offering an effective surf tolerance. These microtrichia not only trap a thin air layer above the cuticle but also maintain a larger air bubble between the insect’s ventral side and legs. The effectiveness of the water repellence was quantitatively characterised on the basis of a known model (Crisp and Thorpe, Discuss Faraday Soc 3:210-220, 1948). The parameters of the model are the contact angle θ (>90°) at the contact line of air/water/microtrichia and the distance between individual microtrichia and their radius. When the microtrichia are 1.1 μm apart and have a radius of 0.1 μm and an estimated contact angle θ of 140°, the air layer is stable against hydrostatic pressures of up to 3 m water column. As shown by a modified version of the model, considerably larger air bubbles can be trapped by the microtrichia cover of the legs up to distances of 0.5 mm from the body. The widely spaced (about 8 μm apart) and longer setae of Clunio are not involved in the formation of air layers and air bubble.
6. Numerical investigation of bubble nonlinear dynamics characteristics
SciTech Connect
Shi, Jie Yang, Desen; Shi, Shengguo; Hu, Bo; Zhang, Haoyang; Jiang, Wei
2015-10-28
The complicated dynamical behaviors of bubble oscillation driven by acoustic wave can provide favorable conditions for many engineering applications. On the basis of Keller-Miksis model, the influences of control parameters, including acoustic frequency, acoustic pressure and radius of gas bubble, are discussed by utilizing various numerical analysis methods, Furthermore, the law of power spectral variation is studied. It is shown that the complicated dynamic behaviors of bubble oscillation driven by acoustic wave, such as bifurcation and chaos, further the stimulated scattering processes are revealed.
7. Numerical investigation of bubble nonlinear dynamics characteristics
Shi, Jie; Yang, Desen; Zhang, Haoyang; Shi, Shengguo; Jiang, Wei; Hu, Bo
2015-10-01
The complicated dynamical behaviors of bubble oscillation driven by acoustic wave can provide favorable conditions for many engineering applications. On the basis of Keller-Miksis model, the influences of control parameters, including acoustic frequency, acoustic pressure and radius of gas bubble, are discussed by utilizing various numerical analysis methods, Furthermore, the law of power spectral variation is studied. It is shown that the complicated dynamic behaviors of bubble oscillation driven by acoustic wave, such as bifurcation and chaos, further the stimulated scattering processes are revealed.
8. Generation of Bubbly Suspensions in Low Gravity
NASA Technical Reports Server (NTRS)
Nahra, Henry K.; Hoffmann, Monica I.; Hussey, Sam; Bell, Kimberly R.
2000-01-01
Generation of a uniform monodisperse bubbly suspension in low gravity is a rather difficult task because bubbles do not detach as easily as on Earth. Under microgravity, the buoyancy force is not present to detach the bubbles as they are formed from the nozzles. One way to detach the bubbles is to establish a detaching force that helps their detachment from the orifice. The drag force, established by flowing a liquid in a cross or co-flow configuration with respect to the nozzle direction, provides this additional force and helps detach the bubbles as they are being formed. This paper is concerned with studying the generation of a bubbly suspension in low gravity in support of a flight definition experiment titled "Behavior of Rapidly Sheared Bubbly Suspension." Generation of a bubbly suspension, composed of 2 and 3 mm diameter bubbles with a standard deviation <10% of the bubble diameter, was identified as one of the most important engineering/science issues associated with the flight definition experiment. This paper summarizes the low gravity experiments that were conducted to explore various ways of making the suspension. Two approaches were investigated. The first was to generate the suspension via a chemical reaction between the continuous and dispersed phases using effervescent material, whereas the second considered the direct injection of air into the continuous phase. The results showed that the reaction method did not produce the desired bubble size distribution compared to the direct injection of bubbles. However, direct injection of air into the continuous phase (aqueous salt solution) resulted in uniform bubble-diameter distribution with acceptable bubble-diameter standard deviation.
9. Doughnut-shaped soap bubbles.
PubMed
Préve, Deison; Saa, Alberto
2015-10-01
Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only factor responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume V and with a fixed equatorial perimeter L. It is well known that the sphere is the solution for V=L(3)/6π(2), and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for V<αL(3)/6π(2), with α≈0.21, such a surface cannot be the usual lens-shaped surface formed by the juxtaposition of two spherical caps, but is rather a toroidal surface. Practically, a doughnut-shaped bubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtaining the global solution for this axisymmetric isoperimetric problem. Our result suggests that deformed bubbles with V<αL(3)/6π(2) cannot be stable and should not exist in foams, for instance. PMID:26565252
10. Doughnut-shaped soap bubbles
Préve, Deison; Saa, Alberto
2015-10-01
Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only factor responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume V and with a fixed equatorial perimeter L . It is well known that the sphere is the solution for V =L3/6 π2 , and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for V <α L3/6 π2 , with α ≈0.21 , such a surface cannot be the usual lens-shaped surface formed by the juxtaposition of two spherical caps, but is rather a toroidal surface. Practically, a doughnut-shaped bubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtaining the global solution for this axisymmetric isoperimetric problem. Our result suggests that deformed bubbles with V <α L3/6 π2 cannot be stable and should not exist in foams, for instance.
11. Mechanisms of single bubble cleaning.
PubMed
Reuter, Fabian; Mettin, Robert
2016-03-01
The dynamics of collapsing bubbles close to a flat solid is investigated with respect to its potential for removal of surface attached particles. Individual bubbles are created by nanosecond Nd:YAG laser pulses focused into water close to glass plates contaminated with melamine resin micro-particles. The bubble dynamics is analysed by means of synchronous high-speed recordings. Due to the close solid boundary, the bubble collapses with the well-known liquid jet phenomenon. Subsequent microscopic inspection of the substrates reveals circular areas clean of particles after a single bubble generation and collapse event. The detailed bubble dynamics, as well as the cleaned area size, is characterised by the non-dimensional bubble stand-off γ=d/Rmax, with d: laser focus distance to the solid boundary, and Rmax: maximum bubble radius before collapse. We observe a maximum of clean area at γ≈0.7, a roughly linear decay of the cleaned circle radius for increasing γ, and no cleaning for γ>3.5. As the main mechanism for particle removal, rapid flows at the boundary are identified. Three different cleaning regimes are discussed in relation to γ: (I) For large stand-off, 1.8<γ<3.5, bubble collapse induced vortex flows touch down onto the substrate and remove particles without significant contact of the gas phase. (II) For small distances, γ<1.1, the bubble is in direct contact with the solid. Fast liquid flows at the substrate are driven by the jet impact with its subsequent radial spreading, and by the liquid following the motion of the collapsing and rebounding bubble wall. Both flows remove particles. Their relative timing, which depends sensitively on the exact γ, appears to determine the extension of the area with forces large enough to cause particle detachment. (III) At intermediate stand-off, 1.1<γ<1.8, only the second bubble collapse touches the substrate, but acts with cleaning mechanisms similar to an effective small γ collapse: particles are removed by
12. Application of the ultrasonic technique and high-speed filming for the study of the structure of air-water bubbly flows
SciTech Connect
Carvalho, R.D.M.; Venturini, O.J.; Tanahashi, E.I.; Neves, F. Jr.; Franca, F.A.
2009-10-15
Multiphase flows are very common in industry, oftentimes involving very harsh environments and fluids. Accordingly, there is a need to determine the dispersed phase holdup using noninvasive fast responding techniques; besides, knowledge of the flow structure is essential for the assessment of the transport processes involved. The ultrasonic technique fulfills these requirements and could have the capability to provide the information required. In this paper, the potential of the ultrasonic technique for application to two-phase flows was investigated by checking acoustic attenuation data against experimental data on the void fraction and flow topology of vertical, upward, air-water bubbly flows in the zero to 15% void fraction range. The ultrasonic apparatus consisted of one emitter/receiver transducer and three other receivers at different positions along the pipe circumference; simultaneous high-speed motion pictures of the flow patterns were made at 250 and 1000 fps. The attenuation data for all sensors exhibited a systematic interrelated behavior with void fraction, thereby testifying to the capability of the ultrasonic technique to measure the dispersed phase holdup. From the motion pictures, basic gas phase structures and different flows patterns were identified that corroborated several features of the acoustic attenuation data. Finally, the acoustic wave transit time was also investigated as a function of void fraction. (author)
13. The impacts of replacing air bubbles with microspheres for the clarification of algae from low cell-density culture.
PubMed
Ometto, Francesco; Pozza, Carlo; Whitton, Rachel; Smyth, Beatrice; Gonzalez Torres, Andrea; Henderson, Rita K; Jarvis, Peter; Jefferson, Bruce; Villa, Raffaella
2014-04-15
Dissolved Air Flotation (DAF) is a well-known coagulation-flotation system applied at large scale for microalgae harvesting. Compared to conventional harvesting technologies DAF allows high cell recovery at lower energy demand. By replacing microbubbles with microspheres, the innovative Ballasted Dissolved Air Flotation (BDAF) technique has been reported to achieve the same algae cell removal efficiency, while saving up to 80% of the energy required for the conventional DAF unit. Using three different algae cultures (Scenedesmus obliquus, Chlorella vulgaris and Arthrospira maxima), the present work investigated the practical, economic and environmental advantages of the BDAF system compared to the DAF system. 99% cells separation was achieved with both systems, nevertheless, the BDAF technology allowed up to 95% coagulant reduction depending on the algae species and the pH conditions adopted. In terms of floc structure and strength, the inclusion of microspheres in the algae floc generated a looser aggregate, showing a more compact structure within single cell alga, than large and filamentous cells. Overall, BDAF appeared to be a more reliable and sustainable harvesting system than DAF, as it allowed equal cells recovery reducing energy inputs, coagulant demand and carbon emissions. PMID:24525066
14. Bubble pinch-off in a rotating flow.
PubMed
Bergmann, Raymond; Andersen, Anders; van der Meer, Devaraj; Bohr, Tomas
2009-05-22
We create air bubbles at the tip of a "bathtub vortex" which reaches to a finite depth. The bathtub vortex is formed by letting water drain through a small hole at the bottom of a rotating cylindrical container. The tip of the needlelike surface dip is unstable at high rotation rates and releases bubbles which are carried down by the flow. Using high-speed imaging we find that the minimal neck radius of the unstable tip decreases in time as a power law with an exponent close to 1/3. This exponent was found by Gordillo et al. [Phys. Rev. Lett. 95, 194501 (2005)10.1103/PhysRevLett.95.194501] to govern gas flow driven pinch-off, and indeed we find that the volume oscillations of the tip creates a considerable air flow through the neck. We argue that the Bernoulli pressure reduction caused by this air flow can become sufficient to overcome the centrifugal forces and cause the final pinch-off. PMID:19519033
15. The hydrodynamics of bubble rise and impact with solid surfaces.
PubMed
Manica, Rogerio; Klaseboer, Evert; Chan, Derek Y C
2016-09-01
A bubble smaller than 1mm in radius rises along a straight path in water and attains a constant speed due to the balance between buoyancy and drag force. Depending on the purity of the system, within the two extreme limits of tangentially immobile or mobile boundary conditions at the air-water interface considerably different terminal speeds are possible. When such a bubble impacts on a horizontal solid surface and bounces, interesting physics can be observed. We study this physical phenomenon in terms of forces, which can be of colloidal, inertial, elastic, surface tension and viscous origins. Recent advances in high-speed photography allow for the observation of phenomena on the millisecond scale. Simultaneous use of such cameras to visualize both rise/deformation and the dynamics of the thin film drainage through interferometry are now possible. These experiments confirm that the drainage process obeys lubrication theory for the spectrum of micrometre to millimetre-sized bubbles that are covered in this review. We aim to bridge the colloidal perspective at low Reynolds numbers where surface forces are important to high Reynolds number fluid dynamics where the effect of the surrounding flow becomes important. A model that combines a force balance with lubrication theory allows for the quantitative comparison with experimental data under different conditions without any fitting parameter. PMID:27378067
16. Determination of the microstructure of gas bubbles in highly purified water by measuring the elements of the laser radiation scattering matrix
SciTech Connect
Bunkin, Nikolai F; Suyazov, N V; Shkirin, A V; Ignat'ev, P S; Indukaev, K V
2009-04-30
Modulation interference microscopy and measurements of the elements of the light scattering matrix showed that doubly distilled water purified from solid impurities contains macroscopic scatterers in the form of micron clusters formed by polydisperse air bubbles with the effective radius 70-90 nm. The fractal dimension of clusters lies within 2.4-2.8 and their concentration is {approx}10{sup 6} cm{sup -3}. (radiation scattering)
17. Fuel system bubble dissipation device
SciTech Connect
Iseman, W.J.
1987-11-03
This patent describes a bubble dissipation device for a fuel system wherein fuel is delivered through a fuel line from a fuel tank to a fuel control with the pressure of the fuel being progressively increased by components including at least one pump stage and an ejector in advance of the pump state. The ejector an ejector casing with a wall defining an elongate tubular flow passage which forms a portion of the fuel line to have all of the fuel flow through the tubular flow passage in flowing from the fuel tank to the fuel control, a nozzle positioned entirely within the tubular flow passage and spaced from the wall to permit fuel flow. The nozzle has an inlet and an outlet with the inlet connected to the pump stage to receive fuel under pressure continuously from the pump stage, a bubble accumulation chamber adjoining and at a level above the ejector casing and operatively connected to the fuel line in advance of the ejector casing. The bubble accumulation chamber is of a size to function as a fuel reservoir and hold an air bubble containing vapor above the level of fuel therein and having an outlet adjacent the bottom thereof operatively connected to the tubular flow passage in the ejector casing at an inlet end, a bubble accumulation chamber inlet above the level of the bubble accumulation chamber outlet whereby fuel can flow through the bubble accumulation chamber from the inlet to the outlet thereof with a bubble in the fuel rising above the fuel level in the bubble accumulation chamber.
18. Behavior of bubbles in glassmelts. II - Dissolution of a stationary bubble containing a diffusing and a nondiffusing gas
NASA Technical Reports Server (NTRS)
Weinberg, M. C.; Onorato, P. I. K.; Uhlmann, D. R.
1980-01-01
The effect of a foreign nondiffusing gas on the rate of shrinkage of an oxygen bubble in a soda-lime-silica melt was studied. The rate of change of bubble radius with time was computed using the quasi-stationary approximation. The effects of melt undersaturation and initial fraction of foreign gas in the bubble are considered and compared with those calculated using previously derived expressions.
19. The Minnaert Bubble: An Acoustic Approach
ERIC Educational Resources Information Center
Devaud, Martin; Hocquet, Thierry; Bacri, Jean-Claude; Leroy, Valentin
2008-01-01
We propose an "ab initio" introduction to the well-known Minnaert pulsating bubble at graduate level. After a brief recall of the standard stuff, we begin with a detailed discussion of the radial movements of an air bubble in water. This discussion is managed from an acoustic point of view, and using the Lagrangian rather than the Eulerian…
20. Anomalous bubble propagation in elastic tubes
Heap, Alexandra; Juel, Anne
2008-08-01
Airway reopening is an important physiological event, as exemplified by the first breath of an infant that inflates highly collapsed airways by driving a finger of air through its fluid-filled lungs. Whereas fundamental models of airway reopening predict the steady propagation of only one type of bubble with a characteristic rounded tip, our experiments reveal a surprising selection of novel bubbles with counterintuitive shapes that reopen strongly collapsed, liquid-filled elastic tubes. Our multiple bubbles are associated with a discontinuous relationship between bubble pressure and speed that sets exciting challenges for modelers.
1. Structure of nanoscale gas bubbles in metals
SciTech Connect
Caro, A. Schwen, D.; Martinez, E.
2013-11-18
A usual way to estimate the amount of gas in a bubble inside a metal is to assume thermodynamic equilibrium, i.e., the gas pressure P equals the capillarity force 2γ/R, with γ the surface energy of the host material and R the bubble radius; under this condition there is no driving force for vacancies to be emitted or absorbed by the bubble. In contrast to the common assumption that pressure inside a gas or fluid bubble is constant, we show that at the nanoscale this picture is no longer valid. P and density can no longer be defined as global quantities determined by an equation of state (EOS), but they become functions of position because the bubble develops a core-shell structure. We focus on He in Fe and solve the problem using both continuum mechanics and empirical potentials to find a quantitative measure of this effect. We point to the need of redefining an EOS for nanoscale gas bubbles in metals, which can be obtained via an average pressure inside the bubble. The resulting EOS, which is now size dependent, gives pressures that differ by a factor of two or more from the original EOS for bubble diameters of 1 nm and below.
2. Bernoulli Suction Effect on Soap Bubble Blowing?
Davidson, John; Ryu, Sangjin
2015-11-01
As a model system for thin-film bubble with two gas-liquid interfaces, we experimentally investigated the pinch-off of soap bubble blowing. Using the lab-built bubble blower and high-speed videography, we have found that the scaling law exponent of soap bubble pinch-off is 2/3, which is similar to that of soap film bridge. Because air flowed through the decreasing neck of soap film tube, we studied possible Bernoulli suction effect on soap bubble pinch-off by evaluating the Reynolds number of airflow. Image processing was utilized to calculate approximate volume of growing soap film tube and the volume flow rate of the airflow, and the Reynolds number was estimated to be 800-3200. This result suggests that soap bubbling may involve the Bernoulli suction effect.
3. Bubble bath soap poisoning
MedlinePlus
... medlineplus.gov/ency/article/002762.htm Bubble bath soap poisoning To use the sharing features on this page, please enable JavaScript. Bubble bath soap poisoning occurs when someone swallows bubble bath soap. ...
4. Discrete Bubble Modeling for Cavitation Bubbles
Choi, Jin-Keun; Chahine, Georges; Hsiao, Chao-Tsung
2007-03-01
Dynaflow, Inc. has conducted extensive studies on non-spherical bubble dynamics and interactions with solid and free boundaries, vortical flow structures, and other bubbles. From these studies, emerged a simplified Surface Averaged Pressure (SAP) spherical bubble dynamics model and a Lagrangian bubble tracking scheme. In this SAP scheme, the pressure and velocity of the surrounding flow field are averaged on the bubble surface, and then used for the bubble motion and volume dynamics calculations. This model is implemented using the Fluent User Defined Function (UDF) as Discrete Bubble Model (DBM). The Bubble dynamics portion can be solved using an incompressible liquid modified Rayleigh-Plesset equation or a compressible liquid modified Gilmore equation. The Discrete Bubble Model is a very suitable tool for the studies on cavitation inception of foils and turbo machinery, bubble nuclei effects, noise from the bubbles, and can be used in many practical problems in industrial and naval applications associated with flows in pipes, jets, pumps, propellers, ships, and the ocean. Applications to propeller cavitation, wake signatures of waterjet propelled ships, bubble-wake interactions, modeling of cavitating jets, and bubble entrainments around a ship will be presented.
5. Breaking waves, turbulence and bubbles
Gemmrich, Johannes; Vagle, Svein; Thomson, Jim
2014-05-01
The air-sea fluxes of heat, momentum, and gases are to a large extent affected by wave-induced turbulence in the near-surface ocean layer, and are generally increased over the fluxes in a law-of-the-wall type boundary layer. However, air-bubbles generated during the wave breaking process may affect the density stratification and in turn reduce turbulence intensity in the near-surface layer. The turbulence field beneath surface waves is rather complex and provides great challenges for detailed observations. We obtained high resolution near-surface velocity profiles, bubble cloud measurements and video recordings of the breaking activity in a coastal strait. Conditions ranged from moderate to strong wind forcing with wind speed ranging from 5 m/s to 20 m/s. Estimates of the dissipation rates of turbulence kinetic energy are calculated from the in-situ velocity measurements. We find dissipation rates, fluctuating by more than two orders of magnitude, are closely linked to the air-fraction associated with micro-bubbles. Combining these turbulence estimates and the bubble cloud characteristics we infer differences in the strength of wave breaking and its effect on wave-induced mixing and air-sea exchange processes.
6. BUBBLE DYNAMICS AT GAS-EVOLVING ELECTRODES
SciTech Connect
Sides, Paul J.
1980-12-01
Nucleation of bubbles, their growth by diffusion of dissolved gas to the bubble surface and by coalescence, and their detachment from the electrode are all very fast phenomena; furthermore, electrolytically generated bubbles range in size from ten to a few hundred microns; therefore, magnification and high speed cinematography are required to observe bubbles and the phenomena of their growth on the electrode surface. Viewing the action from the front side (the surface on which the bubbles form) is complicated because the most important events occur close to the surface and are obscured by other bubbles passing between the camera and the electrode; therefore, oxygen was evolved on a transparent tin oxide "window" electrode and the events were viewed from the backside. The movies showed that coalescence of bubbles is very important for determining the size of bubbles and in the chain of transport processes; growth by diffusion and by coalescence proceeds in series and parallel; coalescing bubbles cause significant fluid motion close to the electrode; bubbles can leave and reattach; and bubbles evolve in a cycle of growth by diffusion and different modes of coalescence. An analytical solution for the primary potential and current distribution around a spherical bubble in contact with a plane electrode is presented. Zero at the contact point, the current density reaches only one percent of its undisturbed value at 30 percent of the radius from that point and goes through a shallow maximum two radii away. The solution obtained for spherical bubbles is shown to apply for the small bubbles of electrolytic processes. The incremental resistance in ohms caused by sparse arrays of bubbles is given by {Delta}R = 1.352 af/kS where f is the void fraction of gas in the bubble layer, a is the bubble layer thickness, k is the conductivity of gas free electrolyte, and S is the electrode area. A densely populated gas bubble layer on an electrode was modeled as a hexagonal array of
7. Dynamics of Single Hydrogen Bubbles at a Platinum Microelectrode.
PubMed
Yang, Xuegeng; Karnbach, Franziska; Uhlemann, Margitta; Odenbach, Stefan; Eckert, Kerstin
2015-07-28
Bubble dynamics, including the formation, growth, and detachment, of single H2 bubbles was studied at a platinum microelectrode during the electrolysis of 1 M H2SO4 electrolyte. The bubbles were visualized through a microscope by a high-speed camera. Electrochemical measurements were conducted in parallel to measure the transient current. The periodic current oscillations, resulting from the periodic formation and detachment of single bubbles, allow the bubble lifetime and size to be predicted from the transient current. A comparison of the bubble volume calculated from the current and from the recorded bubble image shows a gas evolution efficiency increasing continuously with the growth of the bubble until it reaches 100%. Two different substrates, glass and epoxy, were used to embed the Pt wire. While nearly no difference was found with respect to the growth law for the bubble radius, the contact angle differs strongly for the two types of cell. Data provided for the contact point evolution further complete the image of single hydrogen bubble growth. Finally, the velocity field driven by the detached bubble was measured by means of PIV, and the effects of the convection on the subsequent bubble were evaluated. PMID:26133052
8. Acoustical and Optical Characterization of Air Entrapment in Piezo-Driven Inkjet Printheads
de Jong, Jos; Reinten, Hans; Versluis, Michel
2005-11-01
Air entrapment leads to malfunctioning of jet formation in a piezo-driven inkjet printhead. The entrapped air bubbles disturb the acoustics and in many cases cause the droplet formation to stop. Here we will focus on piezo inkjet devices where a voltage pulse applied to a piezo-electric element causes an ink-filled channel to deform, thereby creating a pressure waveform in the ink. The nozzle diameter is typically 30 μm. Droplets are jetted every 50 μs and it is essential that the droplet formation remains stable for an extensive period. Here we detect air entrapment, reveal the air entrapment process, and the time evolution of the entrapped air bubble. The acoustical signal is monitored by using the piezo actuator as a sensor to measure the pressure in the channel after the pulse is applied. This signal is employed to detect air bubbles inside the ink channel and to trigger the optical setup. High speed imaging is employed to perfom optical measurements at microsecond timescales. Once entrapped, the air bubble has an initial radius of 10 μm and oscillates with a frequency near 200 kHz. The radial growth of the bubble is found to be 0.3 μm/ms.
9. Effects of ultrasound frequency and acoustic amplitude on the size of sonochemically active bubbles - Theoretical study.
PubMed
Merouani, Slimane; Hamdaoui, Oualid; Rezgui, Yacine; Guemini, Miloud
2013-05-01
Numerical simulation of chemical reactions inside an isolated spherical bubble of oxygen has been performed for various ambient bubble radii at different frequencies and acoustic amplitudes to study the effects of these two parameters on the range of ambient radius for an active bubble in sonochemical reactions. The employed model combines the dynamic of bubble collapse with the chemical kinetics of single cavitation bubble. Results from this model were compared with some experimental results presented in the literature and good apparent trends between them were observed. The numerical calculations of this study showed that there always exists an optimal ambient bubble radius at which the production of oxidizing species at the end of the bubble collapse attained their upper limit. It was shown that the range of ambient radius for an active bubble increased with increasing acoustic amplitude and decreased with increasing ultrasound frequency. The optimal ambient radius decreased with increasing frequency. Analysis of curves showing optimal ambient radius versus acoustic amplitude for different ultrasonic frequencies indicated that for 200 and 300kHz, the optimal ambient radius increased linearly with increasing acoustic amplitude up to 3atm. However, slight minima of optimal radius were observed for the curves obtained at 500 and 1000kHz. PMID:23187064
10. Bubble coalescence dynamics and supersaturation in electrolytic gas evolution
SciTech Connect
Stover, R.L. |
1996-08-01
The apparatus and procedures developed in this research permit the observation of electrolytic bubble coalescence, which heretofore has not been possible. The influence of bubble size, electrolyte viscosity, surface tension, gas type, and pH on bubble coalescence was examined. The Navier-Stokes equations with free surface boundary conditions were solved numerically for the full range of experimental variables that were examined. Based on this study, the following mechanism for bubble coalescence emerges: when two gas bubbles coalesce, the surface energy decreases as the curvature and surface area of the resultant bubble decrease, and the energy is imparted into the surrounding liquid. The initial motion is driven by the surface tension and slowed by the inertia and viscosity of the surrounding fluid. The initial velocity of the interface is approximately proportional to the square root of the surface tension and inversely proportional to the square root of the bubble radius. Fluid inertia sustains the oblate/prolate oscillations of the resultant bubble. The period of the oscillations varies with the bubble radius raised to the 3/2 power and inversely with the square root of the surface tension. Viscous resistance dampens the oscillations at a rate proportional to the viscosity and inversely proportional to the square of the bubble radius. The numerical simulations were consistent with most of the experimental results. The differences between the computed and measured saddle point decelerations and periods suggest that the surface tension in the experiments may have changed during each run. By adjusting the surface tension in the simulation, a good fit was obtained for the 150-{micro}m diameter bubbles. The simulations fit the experiments on larger bubbles with very little adjustment of surface tension. A more focused analysis should be done to elucidate the phenomena that occur in the receding liquid film immediately following rupture.
11. Models of cylindrical bubble pulsation
PubMed Central
Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hay, Todd A.; Hamilton, Mark F.
2012-01-01
Three models are considered for describing the dynamics of a pulsating cylindrical bubble. A linear solution is derived for a cylindrical bubble in an infinite compressible liquid. The solution accounts for losses due to viscosity, heat conduction, and acoustic radiation. It reveals that radiation is the dominant loss mechanism, and that it is 22 times greater than for a spherical bubble of the same radius. The predicted resonance frequency provides a basis of comparison for limiting forms of other models. The second model considered is a commonly used equation in Rayleigh-Plesset form that requires an incompressible liquid to be finite in extent in order for bubble pulsation to occur. The radial extent of the liquid becomes a fitting parameter, and it is found that considerably different values of the parameter are required for modeling inertial motion versus acoustical oscillations. The third model was developed by V. K. Kedrinskii [Hydrodynamics of Explosion (Springer, New York, 2005), pp. 23–26] in the form of the Gilmore equation for compressible liquids of infinite extent. While the correct resonance frequency and loss factor are not recovered from this model in the linear approximation, it provides reasonable agreement with observations of inertial motion. PMID:22978863
12. Axisymmetric bubble pinch-off at high Reynolds numbers.
PubMed
Gordillo, J M; Sevilla, A; Rodríguez-Rodríguez, J; Martínez-Bazán, C
2005-11-01
Analytical considerations and potential-flow numerical simulations of the pinch-off of bubbles at high Reynolds numbers reveal that the bubble minimum radius, rn, decreases as tau proportional to r2n sqrt[1lnr2n], where tau is the time to break up, when the local shape of the bubble near the singularity is symmetric. However, if the gas convective terms in the momentum equation become of the order of those of the liquid, the bubble shape is no longer symmetric and the evolution of the neck changes to a rn proportional to tau1/3 power law. These findings are verified experimentally. PMID:16383983
13. Approaching behavior of a pair of spherical bubbles in quiescent liquids
2015-11-01
Some unique motions related bubble-bubble interaction, such as equilibrium distance, wake induced lift force, have been proposed by theoretical analysis or numerical simulations. These motions are different from the solid spheres like DKT model (Drafting, Kissing and Tumbling). However, there is a lack of the experimental verification. In this study, we experimentally investigated the motion of a pair of bubbles initially positioned in-line configuration in ultrapure water or an aqueous surfactant solution. The bubble motion were observed by two high speed video cameras. The bubbles Reynolds number was ranged from 50 to 300 and bubbles hold the spherical shape in this range. In ultrapure water, initially the trailing bubble deviated from the vertical line on the leading bubble owing to the wake of the leading bubble. And then, the slight difference of the bubble radius changed the relative motion. When the trailing bubble slightly larger than the leading bubble, the trailing bubble approached to the leading bubble due to it's buoyancy difference. The bubbles attracted and collided only when the bubbles rising approximately side by side configuration. In addition, we will also discuss the motion of bubbles rising in an aqueous surfactant solution.
14. Gas bubble dynamics in soft materials.
PubMed
Solano-Altamirano, J M; Malcolm, John D; Goldman, Saul
2015-01-01
Epstein and Plesset's seminal work on the rate of gas bubble dissolution and growth in a simple liquid is generalized to render it applicable to a gas bubble embedded in a soft elastic solid. Both the underlying diffusion equation and the expression for the gas bubble pressure were modified to allow for the non-zero shear modulus of the medium. The extension of the diffusion equation results in a trivial shift (by an additive constant) in the value of the diffusion coefficient, and does not change the form of the rate equations. But the use of a generalized Young-Laplace equation for the bubble pressure resulted in significant differences on the dynamics of bubble dissolution and growth, relative to an inviscid liquid medium. Depending on whether the salient parameters (solute concentration, initial bubble radius, surface tension, and shear modulus) lead to bubble growth or dissolution, the effect of allowing for a non-zero shear modulus in the generalized Young-Laplace equation is to speed up the rate of bubble growth, or to reduce the rate of bubble dissolution, respectively. The relation to previous work on visco-elastic materials is discussed, as is the connection of this work to the problem of Decompression Sickness (specifically, "the bends"). Examples of tissues to which our expressions can be applied are provided. Also, a new phenomenon is predicted whereby, for some parameter values, a bubble can be metastable and persist for long times, or it may grow, when embedded in a homogeneous under-saturated soft elastic medium. PMID:25382720
15. Gas bubble dynamics in soft materials
Solano-Altamirano, J. M.; Malcolm, John D.; Goldman, Saul
Epstein and Plesset's seminal work on the rate of gas bubble dissolution and growth in a simple liquid is generalized to render it applicable to a gas bubble embedded in a soft elastic medium. Both the underlying diffusion equation and the expression for the gas bubble pressure were modified to allow for the non-zero shear modulus of the elastic medium. The extension of the diffusion equation results in a trivial shift (by an additive constant) in the value of the diffusion coefficient, and does not change the form of the rate equations. But the use of a Generalized Young-Laplace equation for the bubble pressure resulted in significant differences on the dynamics of bubble dissolution and growth, relative to a simple liquid medium. Depending on whether the salient parameters (solute concentration, initial bubble radius, surface tension, and shear modulus) lead to bubble growth or dissolution, the effect of allowing for a non-zero shear modulus in the Generalized Young-Laplace equation is to speed up the rate of bubble growth, or to reduce the rate of bubble dissolution, respectively. The relation to previous work on visco-elastic materials is discussed, as is the connection of this work to the problem of Decompression Sickness (specifically, "the bends"). Examples of tissues to which our expressions can be applied are provided. Also, a new phenomenon is predicted whereby, for some parameter values, a bubble can be metastable and persist for long times, or it may grow, when embedded in a homogeneous under-saturated soft elastic medium.
16. Buoyancy Driven Shear Flows of Bubble Suspensions
NASA Technical Reports Server (NTRS)
Koch, D. L.; Hill, R. J.; Chellppannair, T.; Zenit, R.; Zenit, R.; Spelt, P. D. M.
1999-01-01
In this work the gas volume fraction and the root-mean-squared fluid velocity are measured in buoyancy driven shear flows of bubble suspensions in a tall, inclined, rectangular channel. The experiments are performed under conditions where We << 1a nd Re >> 1, for which comparisons are made with kinetic theory and numerical simulations. Here Re = gamma(a(exp 2)/nu is the Reynolds number and We = rho(gamma(exp 2))a(exp 3)/sigma is the Weber number; gamma is the shear rate, a is the bubble radius, nu is the kinematic viscosity of the liquid, rho is the density of the liquid, and sigma is the surface tension of the gas/liquid interface. Kang et al. calculated the bubble phase pressure and velocity variance of sheared bubble suspensions under conditions where the bubbles are spherical and the liquid phase velocity field can be approximated using potential flow theory, i.e. We= 0 and Re >> 1. Such conditions can be achieved in an experiment using gas bubbles, with a radius of O(0.5mm), in water. The theory requires that there be no average relative motion of the gas and liquid phases, hence the motivation for an experimental program in microgravity. The necessity of performing preliminary, Earth based experiments, however, requires performing experiments where the gas phase rises in the liquid, which significantly complicates the comparison of experiments with theory. Rather than comparing experimental results with theory for a uniform, homogeneous shear flow, experiments can be compared directly with solutions of the averaged equations of motion for bubble suspensions. This requires accounting for the significant lift force acting on the gas phase when the bubbles rise parallel to the average velocity of the sheared suspension. Shear flows can be produced in which the bubble phase pressure gradient, arising from shear induced collisions amongst the bubbles, balances a body force (centrifugal or gravitational) on the gas phase. A steady, non-uniform gas volume fraction
17. Inert gas bubbles in bcc Fe
Gai, Xiao; Smith, Roger; Kenny, S. D.
2016-03-01
The properties of inert gas bubbles in bcc Fe is examined using a combination of static energy minimisation, molecular dynamics and barrier searching methods with empirical potentials. Static energy minimisation techniques indicate that for small Ar and Xe bubbles, the preferred gas to vacancy ratio at 0 K is about 1:1 for Ar and varies between 0.5:1 and 0.9:1 for Xe. In contrast to interstitial He atoms and small He interstitial clusters, which are highly mobile in the lattice, Ar and Xe atoms prefer to occupy substitutional sites and any interstitials present in the lattice soon displace Fe atoms and become substitutional. If a pre-existing bubble is present then there is a capture radius around a bubble which extends up to the 6th neighbour position. Collision cascades can also enlarge an existing bubble by the capture of vacancies. Ar and Xe can diffuse through the lattice through vacancy driven mechanisms but with relatively high energy barriers of 1.8 and 2.0 eV respectively. This indicates that Ar and Xe bubbles are much harder to form than bubbles of He and that such gases produced in a nuclear reaction would more likely be dispersed at substitutional sites without the help of increased temperature or radiation-driven mechanisms.
18. The rising bubble technique for discharge measurements
Luxemburg, W.; Hilgersom, K.; van Eekelen, M.
2010-12-01
The rising bubble technique is an elegant method to determine the full discharge of a river or a canal in a short moment of time. The method is not new [Sargent, 1982], but hardly applied so far. The method applies air bubbles released from the bottom of a river or canal. While the bubbles rise to the surface they are dragged along by the current. The deeper the stream and the faster the current the longer will be the distance they are dragged along. The horizontal displacement L, of the bubbles can be observed at the surface of the stream. To obtain a discharge, the rising velocity vr, of the bubble is required additionally. When the rising velocity is assumed constant the discharge per unit width amounts to q= Lvr. Placing a tube on the bottom of the stream and releasing bubbles at regular intervals results in a complete discharge profile. The ongoing research is focusing on factors affecting the rising velocity, solving practicalities in applying the method in the field and how modern image processing techniques can enhance determining in a glance the distance travelled by the bubbles. Surfacing of air bubbles in a canal
19. The size of active bubbles for the production of hydrogen in sonochemical reaction field.
PubMed
Merouani, Slimane; Hamdaoui, Oualid
2016-09-01
The sonication of aqueous solution generates microscopic cavitation bubbles that may growth and violently collapse to produce highly reactive species (i.e. OH, HO2 and H2O2), hydrogen and emit light, sonoluminescence. The bubble size is a key parameter that influences the chemical activity of the system. This wok aims to study theoretically the size of active bubbles for the production of hydrogen in ultrasonic cavitation field in water using a single bubble sonochemistry model. The effect of several parameters such as frequency of ultrasound, acoustic intensity and liquid temperature on the range of sonochemically active bubbles for the production of hydrogen was clarified. The numerical simulation results showed that the size of active bubbles is an interval which includes an optimum value at which the production rate of H2 is maximal. It was shown that the range of ambient radius for an active bubble as well as the optimum bubble radius for the production of hydrogen increased with increasing acoustic intensity and decreased with increasing ultrasound frequency and bulk liquid temperature. It was found that the range of ambient bubble radius dependence of the operational conditions followed the same trend as those reported experimentally for sonoluminescing bubbles. Comparison with literature data showed a good agreement between the theoretical determined optimum bubble sizes for the production of hydrogen and the experimental reported sizes for sonoluminescing bubbles. PMID:27150777
20. Bubble cloud dynamics in a high-pressure spherical resonator
Anderson, Phillip Andrew
A bubble cloud is a population of bubbles confined to a region within a fluid. Bubble clouds play a large role in a variety of naturally occurring phenomena and man-made applications (e.g., ocean noise, cavitation damage, sonoluminescence, ultrasonic cleaning, drug delivery, lithotripsy). It is important, therefore, to understand the behavior of bubble clouds so that their effects may be enhanced or diminished as desired. This work explores and characterizes the properties of bubble clouds nucleated inside a high-pressure spherical acoustic resonator, in connection with recent interest in acoustic inertial confinement fusion (acoustic ICF). A laser system was developed to repeatably nucleate a cloud of bubbles inside the resonator. The resulting events were then observed, primarily with schlieren imaging methods. Preliminary studies of the bubble cloud dynamics showed the sensitivity of the initial cloud to nucleation parameters including the phase of nucleation, the laser energy, and the acoustic power. After many acoustic cycles, some bubble clouds are observed to evolve into a tight cluster. The formation of these clusters correlates with initial bubble distributions which have a large cloud interaction parameter, β. Cluster dynamics are seen to be largely driven by reconverging shock waves from previous collapses reflected from the resonator's interior surface. Initial expansion of the cluster boundary is on the order of 8 mm/µs and the maximum radius approaches 3 mm. Shock pressures are estimated to be > 10 GPa at a radius of 100 µm using weak shock theory.
1. Bubble formation in additive manufacturing of glass
Luo, Junjie; Gilbert, Luke J.; Peters, Daniel C.; Bristow, Douglas A.; Landers, Robert G.; Goldstein, Jonathan T.; Urbas, Augustine M.; Kinzel, Edward C.
2016-05-01
Bubble formation is a common problem in glass manufacturing. The spatial density of bubbles in a piece of glass is a key limiting factor to the optical quality of the glass. Bubble formation is also a common problem in additive manufacturing, leading to anisotropic material properties. In glass Additive Manufacturing (AM) two separate types of bubbles have been observed: a foam layer caused by the reboil of the glass melt and a periodic pattern of bubbles which appears to be unique to glass additive manufacturing. This paper presents a series of studies to relate the periodicity of bubble formation to part scan speed, laser power, and filament feed rate. These experiments suggest that bubbles are formed by the reboil phenomena why periodic bubbles result from air being trapped between the glass filament and the substrate. Reboil can be detected using spectroscopy and avoided by minimizing the laser power while periodic bubbles can be avoided by a two-step laser melting process to first establish good contact between the filament and substrate before reflowing the track with higher laser power.
2. Acoustic bubble removal method
NASA Technical Reports Server (NTRS)
Trinh, E. H.; Elleman, D. D.; Wang, T. G. (Inventor)
1983-01-01
A method is described for removing bubbles from a liquid bath such as a bath of molten glass to be used for optical elements. Larger bubbles are first removed by applying acoustic energy resonant to a bath dimension to drive the larger bubbles toward a pressure well where the bubbles can coalesce and then be more easily removed. Thereafter, submillimeter bubbles are removed by applying acoustic energy of frequencies resonant to the small bubbles to oscillate them and thereby stir liquid immediately about the bubbles to facilitate their breakup and absorption into the liquid.
3. Discharge coefficients of cooling holes with radiused and chamfered inlets
Hay, N.; Spencer, A.
1991-06-01
The flow of cooling air within the internal passages of gas turbines is controlled and metered using holes in disks and casings. The effects of inlet radiusing and chamfering of these holes on the discharge coefficient are discussed. Experimental results for a range of radiusing and chamfering ratios for holes of different length to diameter ratios are presented, covering the range of pressure ratios of practical interest. The results indicate that radiusing and chamfering are both beneficial in increasing the discharge coefficient. Increases of 10-30 percent are possible. Chamfered holes give the more desirable performance characteristics in addition to being easier to produce than radiused holes.
4. Bubble size prediction in co-flowing streams
van Hoeve, W.; Dollet, B.; Gordillo, J. M.; Versluis, M.; van Wijngaarden, L.; Lohse, D.
2011-06-01
In this paper, the size of bubbles formed through the breakup of a gaseous jet in a co-axial microfluidic device is derived. The gaseous jet surrounded by a co-flowing liquid stream breaks up into monodisperse microbubbles and the size of the bubbles is determined by the radius of the inner gas jet and the bubble formation frequency. We obtain the radius of the gas jet by solving the Navier-Stokes equations for low-Reynolds-number flows and by conservation of momentum. The prediction of the bubble size is based on the system's control parameters only, i.e. the inner gas flow rate Qi, the outer liquid flow rate Qo, and the tube radius R. For a very low gas-to-liquid flow rate ratio (Qi/Qo→0) the bubble radius scales as r_{b}/R \\propto \\sqrt{Q_{i}/Q_{o}} , independently of the inner-to-outer viscosity ratio ηi/ηo and of the type of the velocity profile in the gas, which can be either flat or parabolic, depending on whether high-molecular-weight surfactants cover the gas-liquid interface or not. However, in the case in which the gas velocity profiles are parabolic and the viscosity ratio is sufficiently low, i.e. ηi/ηoLt1, the bubble diameter scales as rb~(Qi/Qo)β, with β smaller than 1/2.
5. The terminal velocity of a bubble in an oscillating flow.
SciTech Connect
Torczynski, John Robert; Kraynik, Andrew Michael; Romero, Louis Anthony
2010-11-01
A bubble in an acoustic field experiences a net 'Bjerknes' force from the nonlinear coupling of its radial oscillations with the oscillating buoyancy force. It is typically assumed that the bubble's net terminal velocity can be found by considering a spherical bubble with the imposed 'Bjerknes stresses'. We have analyzed the motion of such a bubble using a rigorous perturbation approach and found that one must include a term involving an effective mass flux through the bubble that arises from the time average of the second-order nonlinear terms in the kinematic boundary condition. The importance of this term is governed by the dimensionless parameter {alpha} = R{sup 2} {phi}/R{sup 2} {phi} {nu}.-{nu}, where R is the bubble radius, {phi} is the driving frequency, and {nu} is the liquid kinematic viscosity. If {alpha} is large, this term is unimportant, but if {alpha} is small, this term is the dominant factor in determining the terminal velocity.
6. Cavitation bubble dynamics in microfluidic gaps of variable height.
PubMed
Quinto-Su, Pedro A; Lim, Kang Y; Ohl, Claus-Dieter
2009-10-01
We study experimentally the dynamics of laser-induced cavitation bubbles created inside a narrow gap. The gap height, h , is varied from 15 to 400 microm and the resulting bubble dynamics is compared to a semiunbounded fluid. The cavitation bubbles are created with pulsed laser light at constant laser energy and are imaged with a high-speed camera. The bubble lifetime increases with decreasing gap height by up to 50% whereas the maximum projected bubble radius remains constant. Comparing the radial dynamics to potential flow models, we find that with smaller gaps, the bubble-induced flow becomes essentially planar, thus slower flows with reduced shear. These findings might have important consequences for microfluidic applications where it is desirable to tune the strength and range of the interactions such as in the case of cell lysis and cell membrane poration. PMID:19905487
7. Video measurements of near-surface bubble spectra
Bowyer, Peter A.
2001-07-01
Large bubbles >300μm radius have been observed at depths of between 10 cm and 1.2 m using a small video camera attached to a surface following float. In salt water, bubble spectra are presented for both limited fetch and open sea conditions and in fresh water for limited fetch conditions. The void fractions and areas of the observed bubbles are calculated. Measurements were made in a limited range of wind conditions (greater than Beaufort force 5) and depths (between 10 cm and 1.2 m). Video records were analyzed by eye which introduced some uncertainty in the measured size and limited the number of sampled bubbles. Bubble populations are represented by power law spectra (dndr=ar-b). Near the surface, 2 < b < 3 on average; the distribution is very patchy: near breaking waves there are relatively more large bubbles: here 1 < b < 2. Away from the surface, 3.5 < b < 5.
8. A Study on Bubble Departure and Bubble Lift-Off in Sub-Cooled Nucleate Boiling Flows
SciTech Connect
Wu, Wen; Chen, Peipei; Jones, Barclay G.; Newell, Ty A.
2006-07-01
This research examines bubble departure and bubble lift-off phenomena under subcooled nucleate boiling condition, using a high fidelity digital imaging apparatus. Refrigerant R- 134a is chosen as a simulant fluid due to its merits of having smaller surface tension, reduced latent heat, and lower boiling temperature than water. Images at frame rates up to 4000 frames/s were obtained with varying experimental parameters e.g. pressure, inlet sub-cooled level, and flow rate, etc., showing characteristics of bubble behavior under different conditions. Bubble size and position information was calculated via Canny's algorithm for edge detection and Fitzgibbon's algorithm for ellipse fitting. Bubble departure and lift-off radiuses were obtained and compared with existing bubble forces and detachment models proposed by Thorncroft et al., with good agreement observed. (authors)
9. Effect of particle adsorption rates on the disproportionation process in pickering stabilised bubbles.
PubMed
Ettelaie, Rammile; Murray, Brent
2014-05-28
The degree of shrinkage of particle stabilised bubbles of various sizes, in a polydisperse bubble dispersion, has been investigated in the light of the finite adsorption times for the particles and the disproportionation kinetics of the bubbles. For the case where the system contains an abundance of particles we find a threshold radius, above which bubbles are stabilised without any significant reduction in their size. Bubbles with an initial radius below this threshold on the other hand undergo a large degree of shrinkage prior to stabilisation. As the ratio of the available particles to the bubbles is reduced, it is shown that the final bubble size, for the larger bubbles in the distribution, becomes increasingly governed by the number of particles, rather than their adsorption time per se. For systems with "adsorption controlled" shrinkage ratio, the final bubble distribution is found to be wider than the initial one, while for a "particle number controlled" case it is actually narrower. Starting from a unimodal bubble size distribution, we predict that at intermediate times, prior to the full stabilisation of all bubbles, the distribution breaks up into a bimodal one. However, the effect is transient and a unimodal final bubble size distribution is recovered, when all the bubbles are stabilised by the particles. PMID:24880317
10. Primary Particles from different bubble generation techniques
Butcher, A. C.; King, S. M.; Rosenoern, T.; Nilsson, E. D.; Bilde, M.
2011-12-01
Sea spray aerosols (SSA) are of major interest to global climate models due to large uncertainty in their emissions and ability to form Cloud Condensation Nuclei (CCN). In general, SSA are produced from wind breaking waves that entrain air and cause bubble bursting on the ocean surface. Preliminary results are presented for bubble generation, bubble size distribution, and CCN activity for laboratory generated SSA. In this study, the major processes of bubble formation are examined with respect to particle emissions. It has been suggested that a plunging jet closely resembles breaking wave bubble entrainment processes and subsequent bubble size distributions (Fuentes, Coe et al. 2010). Figure 1 shows the different particle size distributions obtained from the various bubble generation techniques. In general, frits produce a higher concentration of particles with a stronger bimodal particle size distribution than the various jet configurations used. The experiments consist of a stainless steel cylinder closed at both ends with fittings for aerosol sampling, flow connections for the recirculating jet, and air supply. Bubble generation included a recirculating jet with 16 mm or 4 mm nozzles, a stainless steel frit, or a ceramic frit. The chemical composition of the particles produced via bubble bursting processes has been probed using particle CCN activity. The CCN activity of sodium chloride, artificial sea salt purchased from Tropic Marin, and laboratory grade artificial sea salt (Kester, Duedall et al. 1967) has been compared. Considering the the limits of the shape factor as rough error bars for sodium chloride and bubbled sea salt, the CCN activity of artificial sea salt, Tropic Marin sea salt, and sodium chloride are not significantly different. This work has been supported by the Carlsberg Foundation.
11. Determination of surface tension from the measurement of internal pressure of mini soap bubbles
Behroozi, F.; Behroozi, P. S.
2011-11-01
We review the elementary theory that gives the internal pressure of a soap bubble in terms of its radius and surface tension. The theory is generalized to relate the pressure difference across any element of a soap film to its local curvature. This result is used to introduce the concept of the mean curvature of a surface element and is applied to a double soap bubble to obtain the relation between the three radii that characterize its geometry. We also describe a simple setup, suitable for the undergraduate laboratory, to produce mini bubbles and to obtain the surface tension of the soap solution by measuring the radius and internal pressure of the bubbles.
12. Computational study of the dynamics of two interacting bubbles in a megasonic field.
PubMed
Ochiai, Naoya; Ishimoto, Jun
2015-09-01
Clarification of the mechanism of particle removal by megasonic cleaning and control of cavitation bubbles in the megasonic field are essential for cleaning of nanodevices without pattern damage. Multiple bubble interactions complicate the mechanism of particle removal. Therefore, it is important to understand multiple bubble dynamics to clarify the mechanism of particle removal by megasonic cleaning. In the present study, the dynamics of two bubbles in a megasonic field with several initial radii and initial separation distances were simulated by numerical analysis using a compressible locally homogeneous model of a gas-liquid two-phase medium. The present numerical method simulated the various complex behaviors of two bubbles, which are repulsive motion, coalescence, periodic and stable motion of the separation distance, and bubble breakup. The initial separation distance strongly affected the behavior of the two bubbles because the effect of the secondary pressure induced by the oscillation of one bubble on the other bubble depends on the separation distance. In particular, when the equilibrium radii are larger than the resonant radius and the radius of one or both bubbles is close to the resonant radius, the bubbles can show characteristic behaviors, such as periodic and stable motion of the separation distance. PMID:25892462
13. The Minnaert bubble: an acoustic approach
Devaud, Martin; Hocquet, Thierry; Bacri, Jean-Claude; Leroy, Valentin
2008-11-01
We propose an ab initio introduction to the well-known Minnaert pulsating bubble at graduate level. After a brief recall of the standard stuff, we begin with a detailed discussion of the radial movements of an air bubble in water. This discussion is managed from an acoustic point of view, and using the Lagrangian rather than the Eulerian variables. In unbounded water, the air-water system has a continuum of eigenmodes, some of them correspond to regular Fabry-Pérot resonances. A singular resonance, the lowest one, is shown to coincide with that of Minnaert. In bounded water, the eigenmodes spectrum is discrete, with a finite fundamental frequency. A spectacular quasi-locking of the latter occurs if it happens to exceed the Minnaert frequency, which provides an unforeseen one-bubble alternative version of the famous 'hot chocolate effect'. In the (low) frequency domain in which sound propagation inside the bubble reduces to a simple 'breathing' (i.e. inflation/deflation), the light air bubble can be 'dressed' by the outer water pressure forces, and is turned into the heavy Minnaert bubble. Thanks to this unexpected renormalization process, we demonstrate that the Minnaert bubble definitely behaves like a true harmonic oscillator of the spring-bob type, but with a damping term and a forcing term in apparent disagreement with those commonly admitted in the literature. Finally, we underline the double role played by the water. In order to tell the water motion associated with water compressibility (i.e. the sound) from the simple incompressible accompaniment of the bubble breathing, we introduce a new picture analogous to the electromagnetic radiative picture in Coulomb gauge, which naturally leads us to split the water displacement in an instantaneous and a retarded part. The Minnaert renormalized mass of the dressed bubble is then automatically recovered.
14. The interaction of positive streamers with bubbles floating on a liquid surface
Akishev, Yu; Arefi-Khonsari, F.; Demir, A.; Grushin, M.; Karalnik, V.; Petryakov, A.; Trushkin, N.
2015-12-01
This paper reports the results of a preliminary investigation on the interaction of a streamer discharge in air with bubbles filled with air and floating on a liquid surface. The bubbles are formed of tap water and transformer oil. It was shown that the strike of the streamer in a bubble is followed by the full bubble destroying. However, scenarios of the streamer discharge interaction with a conductive water bubble and dielectric oil bubble are different in their concrete details. A positive streamer smoothly and slowly slides on an external surface of a water bubble, but the streamer striking in an oil bubble quickly perforates it and penetrates into the bubble. The mechanisms for water and oil bubble destroying are discussed. The applicability of the results obtained to plasma-liquid systems based on the use of foam is discussed as well.
15. Development of a simple model for predicting the spark-induced bubble behavior under different ambient pressures
Zhang, L. C.; Zhu, X. L.; Huang, Y. F.; Liu, Z.; Yan, K.
2016-07-01
In this paper, a simple model was developed to predict the dynamics of a spark-induced bubble under different ambient pressures. This work helps in developing a deep-towed plasma sparker, as the model can predict the dynamics of bubbles subjected to very high ambient pressures (about 20 MPa) which normally are difficult to obtain experimentally. Experimental results indicate that the maximum bubble radius for a fixed discharge energy decreases as a power-law function of the ambient pressure up to 1.0 MPa; the bubble period also decreases quickly with increasing ambient pressure. For a constant value of the ratio of bubble energy to discharge energy, the modeling results for both maximum radius and bubble period are in good agreement with the experimental results. Both sets of results indicate that the bubble period is proportional to the maximum radius under different ambient pressures.
16. Bubble growth by rectified diffusion at high gas supersaturation levels.
PubMed
Ilinskii, Yurii A; Wilson, Preston S; Hamilton, Mark F
2008-10-01
For high gas supersaturation levels in liquids, on the order of 300% as predicted in capillaries of marine mammals following a series of dives [D. S. Houser, R. Howard, and S. Ridgway, J. Theor. Biol. 213, 183-195 (2001)], standard mathematical models of both static and rectified diffusion are found to underestimate the rate of bubble growth by 10%-20%. The discrepancy is demonstrated by comparing predictions based on existing mathematical models with direct numerical solutions of the differential equations for gas diffusion in the liquid and thermal conditions in the bubble. Underestimation of bubble growth by existing mathematical models is due to the underlying assumption that the gas concentration in the liquid is given by its value for a bubble of constant equilibrium radius. This assumption is violated when high supersaturation causes the bubble to grow too fast in relation to the time scale associated with diffusion. Rapid bubble growth results in an increased gas concentration gradient at the bubble wall and therefore a growth rate in excess of predictions based on constant equilibrium bubble radius. PMID:19062834
17. Steady State Vapor Bubble in Pool Boiling
Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C.; Maroo, Shalabh C.
2016-02-01
Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics.
18. Steady State Vapor Bubble in Pool Boiling.
PubMed
Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C; Maroo, Shalabh C
2016-01-01
Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics. PMID:26837464
19. Steady State Vapor Bubble in Pool Boiling
PubMed Central
Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C.; Maroo, Shalabh C.
2016-01-01
Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics. PMID:26837464
20. Air
MedlinePlus
... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...
1. A bubble detection system for propellant filling pipeline
Wen, Wen; Zong, Guanghua; Bi, Shusheng
2014-06-01
This paper proposes a bubble detection system based on the ultrasound transmission method, mainly for probing high-speed bubbles in the satellite propellant filling pipeline. First, three common ultrasonic detection methods are compared and the ultrasound transmission method is used in this paper. Then, the ultrasound beam in a vertical pipe is investigated, suggesting that the width of the beam used for detection is usually smaller than the internal diameter of the pipe, which means that when bubbles move close to the pipe wall, they may escape from being detected. A special device is designed to solve this problem. It can generate the spiral flow to force all the bubbles to ascend along the central line of the pipe. In the end, experiments are implemented to evaluate the performance of this system. Bubbles of five different sizes are generated and detected. Experiment results show that the sizes and quantity of bubbles can be estimated by this system. Also, the bubbles of different radii can be distinguished from each other. The numerical relationship between the ultrasound attenuation and the bubble radius is acquired and it can be utilized for estimating the unknown bubble size and measuring the total bubble volume.
2. A bubble detection system for propellant filling pipeline.
PubMed
Wen, Wen; Zong, Guanghua; Bi, Shusheng
2014-06-01
This paper proposes a bubble detection system based on the ultrasound transmission method, mainly for probing high-speed bubbles in the satellite propellant filling pipeline. First, three common ultrasonic detection methods are compared and the ultrasound transmission method is used in this paper. Then, the ultrasound beam in a vertical pipe is investigated, suggesting that the width of the beam used for detection is usually smaller than the internal diameter of the pipe, which means that when bubbles move close to the pipe wall, they may escape from being detected. A special device is designed to solve this problem. It can generate the spiral flow to force all the bubbles to ascend along the central line of the pipe. In the end, experiments are implemented to evaluate the performance of this system. Bubbles of five different sizes are generated and detected. Experiment results show that the sizes and quantity of bubbles can be estimated by this system. Also, the bubbles of different radii can be distinguished from each other. The numerical relationship between the ultrasound attenuation and the bubble radius is acquired and it can be utilized for estimating the unknown bubble size and measuring the total bubble volume. PMID:24985851
3. A bubble detection system for propellant filling pipeline
SciTech Connect
Wen, Wen; Zong, Guanghua; Bi, Shusheng
2014-06-15
This paper proposes a bubble detection system based on the ultrasound transmission method, mainly for probing high-speed bubbles in the satellite propellant filling pipeline. First, three common ultrasonic detection methods are compared and the ultrasound transmission method is used in this paper. Then, the ultrasound beam in a vertical pipe is investigated, suggesting that the width of the beam used for detection is usually smaller than the internal diameter of the pipe, which means that when bubbles move close to the pipe wall, they may escape from being detected. A special device is designed to solve this problem. It can generate the spiral flow to force all the bubbles to ascend along the central line of the pipe. In the end, experiments are implemented to evaluate the performance of this system. Bubbles of five different sizes are generated and detected. Experiment results show that the sizes and quantity of bubbles can be estimated by this system. Also, the bubbles of different radii can be distinguished from each other. The numerical relationship between the ultrasound attenuation and the bubble radius is acquired and it can be utilized for estimating the unknown bubble size and measuring the total bubble volume.
4. Magma mixing enhanced by bubble segregation
Wiesmaier, S.; Morgavi, D.; Renggli, C.; Perugini, D.; De Campos, C. P.; Hess, K.-U.; Ertel-Ingrisch, W.; Lavallée, Y.; Dingwell, D. B.
2015-04-01
That rising bubbles may significantly affect magma mixing paths has already been demon strated by analogue experiments. Here, for the first time, bubble-advection experiments are performed employing volcanic melts at magmatic temperatures. Cylinders of basaltic glass were placed below cylinders of rhyolite glass. Upon melting, interstitial air formed bubbles that rose into the rhyolite melt, thereby entraining tails of basaltic liquid. The formation of plume-like filaments of advected basalt within the rhyolite was characterized by microCT and subsequent high-resolution EMP analyses. Melt entrainment by bubble ascent appears to be an efficient mechanism for mingling volcanic melts of highly contrasting compositions and properties. MicroCT imaging reveals bubbles trailing each other and multiple filaments coalescing into bigger ones. Rheological modelling of the filaments yields viscosities of up to 2 orders of magnitude lower than for the surrounding rhyolitic liquid. Such a viscosity contrast implies that bubbles rising successively are likely to follow this pathway of low resistance that previously ascending bubbles have generated. Filaments formed by multiple bubbles would thus experience episodic replenishment with mafic material. Inevitable implications for the concept of bubble advection in magma mixing include thereby both an acceleration of mixing because of decreased viscous resistance for bubbles inside filaments and non-conventional diffusion systematics because of intermittent supply of mafic material (instead of a single pulse) inside a material. Inside the filaments, the mafic material was variably hybridised to andesitic through rhyolitic composition. Compositional profiles alone are ambiguous, however, to determine whether single or multiple bubbles were involved during formation of a filament. Statistical analysis, employing concentration variance as measure of homogenisation, demonstrates that also filaments appearing as single-bubble filaments
5. Scaling and Instabilities in Bubble Pinch-Off
Burton, J. C.; Waldrep, R.; Taborek, P.
2005-05-01
We have used a 100 000 frame-per-second video to analyze the pinch-off of nitrogen gas bubbles in fluids with a wide range of viscosity. If the external fluid is highly viscous (ηext>100 cP), the bubble neck radius is proportional to the time before break, τ, and decreases smoothly to zero. If the external fluid has low viscosity (ηext<10 cP), the radius scales as τ1/2 until an instability develops in the gas bubble, which causes the neck to rupture and tear apart. Finally, if the viscosity of the external fluid is in an intermediate range, an elongated thread is formed, which breaks apart into micron-sized bubbles.
6. Shrinkage of bubbles and drops in the lattice Boltzmann equation method for nonideal gases.
PubMed
Zheng, Lin; Lee, Taehun; Guo, Zhaoli; Rumschitzki, David
2014-03-01
One characteristic of multiphase lattice Boltzmann equation (LBE) methods is that the interfacial region has a finite (i.e., noninfinitesimal) thickness known as a diffuse interface. In simulations of, e.g., bubble or drop dynamics, for problems involving nonideal gases, one frequently observes that the diffuse interface method produces a spontaneous, nonphysical shrinkage of the bubble or drop radius. In this paper, we analyze in detail a single-fluid two-phase model and use a LBE model for nonideal gases in order to explain this fundamental problem. For simplicity, we only investigate the static bubble or droplet problem. We find that the method indeed produces a density shift, bubble or droplet shrinkage, as well as a critical radius below which the bubble or droplet eventually vanishes. Assuming that the ratio between the interface thickness D and the initial bubble or droplet radius r0 is small, we analytically show the existence of this density shift, bubble or droplet radius shrinkage, and critical bubble or droplet survival radius. Numerical results confirm our analysis. We also consider droplets on a solid surface with different curvatures, contact angles, and initial droplet volumes. Numerical results show that the curvature, contact angle, and the initial droplet volume have an effect on this spontaneous shrinkage process, consistent with the survival criterion. PMID:24730962
7. Forces on ellipsoidal bubbles in a turbulent shear layer
Ford, Barry; Loth, Eric
1998-01-01
The objective of this research was to gain fundamental knowledge of the drag and lift forces on ellipsoidal air bubbles in water in a turbulent flow. This was accomplished by employing a cinematic two-phase particle image velocimetry (PIV) system to evaluate bubbly flow in a two-stream, turbulent, planar free shear layer of filtered tap water. Ellipsoidal air bubbles with nominal diameters from 1.5 to 4.5 mm were injected directly into the shear layer through a single slender tube. The cinematic PIV allowed for high resolution of the unsteady liquid velocity vector field. Triple-pulsed bubble images were obtained in a temporal sequence, such that the bubble size and bubble trajectory could be accurately determined. The bubble's oscillation characteristics, velocity, acceleration, and buoyancy force were obtained from the trajectory data. A bubble dynamic equation was then applied to allow determination of the time-evolving lift and drag forces acting upon bubbles within the shear layer. The results indicate that for a fixed bubble diameter (and fixed Bond and Morton numbers), the drag coefficient decreases for an increasing Reynolds number. This is fundamentally different than the increasing drag coefficient trend seen for ellipsoidal bubbles rising in quiescent baths for increasing diameter (and increasing Bond number), but is qualitatively consistent with the trend for spherical bubbles. A new empirical expression for the dependence of the drag coefficient on Reynolds number for air bubbles in tap water for both quiescent and turbulent flows is constructed herein. Finally, the instantaneous side forces measured in this study were dominated by the inherent deformation-induced vortex shedding of the bubble wake rather than the inviscid lift force based on the background fluid vorticity.
8. Bubble - Crystal Interactions in Magmatic Three-Phase Systems
Belien, I.; Cashman, K.; Rempel, A.; Pioli, L.; Pistolesi, M.
2007-12-01
The influence of crystals on the movement of bubbles through basaltic magmas is poorly understood. We study the interaction of bubbles with a suspension of crystals in a viscous fluid through analog experiments. In our experiments, an air bubble rises through a suspension of plastic beads in a viscous corn syrup - water mixture; we vary bubble volumes, crystal spacings and fluid viscosities. We observe the following change in interaction styles with increasing bubble volume: (1) bubble migration through the crystal network with little bubble deformation, (2) bubble movement through the crystal network with deformation (and sometimes bubble splitting), and (3) displacement of the liquid-crystal mixture by the rising bubble. Interactions change from type (1) to (2) when the bubble is approximately the same size as the crystals forming the network. Transition to type (3) behavior depends on both bubble volume and the thickness of the crystal-liquid layer. In all cases, bubble rise is impeded by the presence of crystals. Preliminary results suggest that impedance is most pronounced for bubbles slightly larger than the crystals (a condition that promotes the maximum bubble deformation). Additionally, very small bubbles may be trapped for long times in the crystal network, suggesting that a shallow reservoir of crystal-rich magma may actually trap rising bubbles from below. These observations provide an alternative interpretation to that of small undeformed bubbles representing late-stage bubble nucleation and large irregularly shaped bubbles forming by coalescence of smaller bubbles (e.g. Lautze and Houghton, 2006). Furthermore, we observe in our experiments that large bubbles can spread out and move laterally underneath a crystal layer. This is not usually considered in models of bubble migration and may explain focusing of gas escape from magma reservoirs and volcanic vents. We apply our experimental results to analysis of bubble populations at Stromboli volcano
9. How are soap bubbles blown? Fluid dynamics of soap bubble blowing
Davidson, John; Lambert, Lori; Sherman, Erica; Wei, Timothy; Ryu, Sangjin
2013-11-01
Soap bubbles are a common interfacial fluid dynamics phenomenon having a long history of delighting not only children and artists but also scientists. In contrast to the dynamics of liquid droplets in gas and gas bubbles in liquid, the dynamics of soap bubbles has not been well documented. This is possibly because studying soap bubbles is more challenging due to there existing two gas-liquid interfaces. Having the thin-film interface seems to alter the characteristics of the bubble/drop creation process since the interface has limiting factors such as thickness. Thus, the main objective of this study is to determine how the thin-film interface differentiates soap bubbles from gas bubbles and liquid drops. To investigate the creation process of soap bubbles, we constructed an experimental model consisting of air jet flow and a soap film, which consistently replicates the conditions that a human produces when blowing soap bubbles, and examined the interaction between the jet and the soap film using the high-speed videography and the particle image velocimetry.
10. Preheating in bubble collisions
SciTech Connect
Zhang Jun; Piao Yunsong
2010-08-15
In a landscape with metastable minima, the bubbles will inevitably nucleate. We show that when the bubbles collide, due to the dramatic oscillation of the field at the collision region, the energy deposited in the bubble walls can be efficiently released by the explosive production of the particles. In this sense, the collision of bubbles is actually highly inelastic. The cosmological implications of this result are discussed.
11. Experimental Visualization of Bubble Formation from an Orifice In Microgravity in the Presence of Electric Fields
NASA Technical Reports Server (NTRS)
Herman, C.; Iacona, E.; Foldes, I. B.; Suner, G.; Milburn, C.
2002-01-01
The formation of air bubbles injected into a stagnant, isothermal liquid in microgravity through an orifice was studied. The bubbles grew very large in microgravity. They attained a nearly spherical shape and showed pronounced affinity towards coalescence in the absence of electric fields and other perturbations. Under the influence of electric fields, periodic detachment was observed, with bubble sizes larger than in terrestrial conditions. The bubble shape was elongated. After detachment, the bubbles moved away from the electrode at which they formed without coalescing with other bubbles. Experimental data on bubble shape and size at detachment showed good agreement with models.
12. Distal radius fractures: current concepts.
PubMed
Schneppendahl, Johannes; Windolf, Joachim; Kaufmann, Robert A
2012-08-01
Despite the frequency of distal radius fractures, the optimal treatment remains without consensus opinion. A trend toward increased distal radius fracture open reduction and internal fixation has been identified, with biomechanical and clinical studies suggesting treatment advantages of certain fixation methods over others. Well-controlled patient trials are still missing to lend objective findings to management algorithms. This article reviews the literature over the past 5 years to guide our management regarding this common upper-extremity injury. PMID:22763062
13. Spherical bubble motion in a turbulent boundary layer
Felton, Keith; Loth, Eric
2001-09-01
Monodisperse dilute suspensions of spherical air bubbles in a tap-water turbulent vertical boundary layer were experimentally studied to note their motion and distribution. Bubbles with diameters of 0.37-1.2 mm were injected at various transverse wall-positions for free-stream velocities between 0.4 and 0.9 m/s. The bubbles were released from a single injector at very low frequencies such that two-way coupling and bubble-bubble interaction were negligible. The experimental diagnostics included ensemble-averaged planar laser intensity profiles for bubble concentration distribution, as well as Cinematic Particle Image Velocimetry with bubble tracking for bubble hydrodynamic forces. A variety of void distributions within the boundary layer were found. For example, there was a tendency for bubbles to collect along the wall for higher Stokes number conditions, while the lower Stokes number conditions produced Gaussian-type profiles throughout the boundary layer. In addition, three types of bubble trajectories were observed—sliding bubbles, bouncing bubbles, and free-dispersion bubbles. Instantaneous liquid forces acting on individual bubbles in the turbulent flow were also obtained to provide the drag and lift coefficients (with notable experimental uncertainty). These results indicate that drag coefficient decreases with increasing Reynolds number as is conventionally expected but variations were observed. In general, the instantaneous drag coefficient (for constant bubble Reynolds number) tended to be reduced as the turbulence intensity increased. The averaged lift coefficient is higher than that given by inviscid theory (and sometimes even that of creeping flow theory) and tends to decrease with increasing bubble Reynolds number.
14. Hadron bubble evolution into the quark sea
SciTech Connect
Freese, K. ); Adams, F.C. )
1990-04-15
A solution is presented for the evolution of hadron bubbles which nucleate in the quark sea if there is a first-order quark-hadron phase transition at a temperature {ital T}{sub {ital c}} on the order of 100 MeV. We make three assumptions: (1) the dominant mechanism for transport of latent heat is radiative, e.g., neutrinos; (2) the distance between nucleation sites is greater than the neutrino mean free path; and (3) the effects of hydrodynamic flow can be neglected. Bubbles nucleate with a characteristic radius 1 fm/{Delta}, where {Delta} is a dimensionless parameter for the undercooling (we take {Delta}{ge}10{sup {minus}4}, so that the expansion of the Universe can be neglected). We argue that bubbles grow stably and remain spherical until the radius becomes as large as the neutrino mean free path, {ital l}{congruent}10 cm. The growth then becomes diffusion limited and the bubbles become unstable to formation of dendrites, or fingerlike structures, because latent heat can diffuse away more easily from long fingers than from spheres. We study the nonlinear evolution of structure with a geometrical model'' and argue that the hadron bubbles ultimately look like stringy seaweed. The percolation of seaweed-shaped bubbles can leave behind regions of quark phase that are quite small. In fact, one might expect the typical scale to be {ital L}{sub {ital Q}}={ital l}{congruent}10 cm. Protons can easily diffuse out of such small regions (and neutrons back in). Thus, these instabilities can lead to important modifications of inhomogeneous nucleosynthesis, which requires {ital L}{sub {ital Q}}{approx gt}1 m.
15. Hadron bubble evolution into the quark sea
1990-04-01
A solution is presented for the evolution of hadron bubbles which nucleate in the quark sea if there is a first-order quark-hadron phase transition at a temperature Tc on the order of 100 MeV. We make three assumptions: (1) the dominant mechanism for transport of latent heat is radiative, e.g., neutrinos; (2) the distance between nucleation sites is greater than the neutrino mean free path; and (3) the effects of hydrodynamic flow can be neglected. Bubbles nucleate with a characteristic radius 1 fm/Δ, where Δ is a dimensionless parameter for the undercooling (we take Δ>=10-4, so that the expansion of the Universe can be neglected). We argue that bubbles grow stably and remain spherical until the radius becomes as large as the neutrino mean free path, l~=10 cm. The growth then becomes diffusion limited and the bubbles become unstable to formation of dendrites, or fingerlike structures, because latent heat can diffuse away more easily from long fingers than from spheres. We study the nonlinear evolution of structure with a geometrical model'' and argue that the hadron bubbles ultimately look like stringy seaweed. The percolation of seaweed-shaped bubbles can leave behind regions of quark phase that are quite small. In fact, one might expect the typical scale to be LQ=l~=10 cm. Protons can easily diffuse out of such small regions (and neutrons back in). Thus, these instabilities can lead to important modifications of inhomogeneous nucleosynthesis, which requires LQ>~1 m.
16. Bursting the Taylor cone bubble
2014-11-01
A soap bubble fixed on a surface and placed in an electric field will take on the shape of a cone rather than constant curvature (dome) when the electrical field is not present. The phenomenon was introduced by J. Zeleny (1917) and studied extensively by C.T. Wilson & G.I. Taylor (1925). We revisit the Taylor cone problem by studying the deformation and bursting of soap bubbles in a point charge electric field. A single bubble takes on the shape of a cone in the electric field and a high-speed camera equipped with a micro-lens is used to observe the unsteady dynamics at the tip. Rupture occurs as a very small piece of the tip is torn away from the bubble toward the point charge. Based on experiments, a theoretical model is developed that predicts when rupture should occur. This study may help in the design of foam-removal techniques in engineering and provide a better understanding of an electrified air-liquid interface.
17. Finite-sized gas bubble motion in a blood vessel: Non-Newtonian effects
PubMed Central
Mukundakrishnan, Karthik; Ayyaswamy, Portonovo S.; Eckmann, David M.
2009-01-01
We have numerically investigated the axisymmetric motion of a finite-sized nearly occluding air bubble through a shear-thinning Casson fluid flowing in blood vessels of circular cross section. The numerical solution entails solving a two-layer fluid model—a cell-free layer and a non-Newtonian core together with the gas bubble. This problem is of interest to the field of rheology and for gas embolism studies in health sciences. The numerical method is based on a modified front-tracking method. The viscosity expression in the Casson model for blood (bulk fluid) includes the hematocrit [the volume fraction of red blood cells (RBCs)] as an explicit parameter. Three different flow Reynolds numbers, Reapp=ρlUmaxd/μapp, in the neighborhood of 0.2, 2, and 200 are investigated. Here, ρl is the density of blood, Umax is the centerline velocity of the inlet Casson profile, d is the diameter of the vessel, and μapp is the apparent viscosity of whole blood. Three different hematocrits have also been considered: 0.45, 0.4, and 0.335. The vessel sizes considered correspond to small arteries, and small and large arterioles in normal humans. The degree of bubble occlusion is characterized by the ratio of bubble to vessel radius (aspect ratio), λ, in the range 0.9≤λ≤1.05. For arteriolar flow, where relevant, the Fahraeus-Lindqvist effects are taken into account. Both horizontal and vertical vessel geometries have been investigated. Many significant insights are revealed by our study: (i) bubble motion causes large temporal and spatial gradients of shear stress at the “endothelial cell” (EC) surface lining the blood vessel wall as the bubble approaches the cell, moves over it, and passes it by; (ii) rapid reversals occur in the sign of the shear stress (+ → − → +) imparted to the cell surface during bubble motion; (iii) large shear stress gradients together with sign reversals are ascribable to the development of a recirculation vortex at the rear of the bubble
18. Finite-sized gas bubble motion in a blood vessel: Non-Newtonian effects
Mukundakrishnan, Karthik; Ayyaswamy, Portonovo S.; Eckmann, David M.
2008-09-01
We have numerically investigated the axisymmetric motion of a finite-sized nearly occluding air bubble through a shear-thinning Casson fluid flowing in blood vessels of circular cross section. The numerical solution entails solving a two-layer fluid model—a cell-free layer and a non-Newtonian core together with the gas bubble. This problem is of interest to the field of rheology and for gas embolism studies in health sciences. The numerical method is based on a modified front-tracking method. The viscosity expression in the Casson model for blood (bulk fluid) includes the hematocrit [the volume fraction of red blood cells (RBCs)] as an explicit parameter. Three different flow Reynolds numbers, Reapp=ρlUmaxd/μapp , in the neighborhood of 0.2, 2, and 200 are investigated. Here, ρl is the density of blood, Umax is the centerline velocity of the inlet Casson profile, d is the diameter of the vessel, and μapp is the apparent viscosity of whole blood. Three different hematocrits have also been considered: 0.45, 0.4, and 0.335. The vessel sizes considered correspond to small arteries, and small and large arterioles in normal humans. The degree of bubble occlusion is characterized by the ratio of bubble to vessel radius (aspect ratio), λ , in the range 0.9⩽λ⩽1.05 . For arteriolar flow, where relevant, the Fahraeus-Lindqvist effects are taken into account. Both horizontal and vertical vessel geometries have been investigated. Many significant insights are revealed by our study: (i) bubble motion causes large temporal and spatial gradients of shear stress at the “endothelial cell” (EC) surface lining the blood vessel wall as the bubble approaches the cell, moves over it, and passes it by; (ii) rapid reversals occur in the sign of the shear stress (+ → - → +) imparted to the cell surface during bubble motion; (iii) large shear stress gradients together with sign reversals are ascribable to the development of a recirculation vortex at the rear of the bubble
19. Non-intrusive measurements of bubble size and velocity
Tassin, A. L.; Nikitopoulos, D. E.
1995-06-01
A non-intrusive measuring technique based on video-imaging has been developed for the measurement of bubble size, velocity and frequency. Measurements carried out with this method have been compared to those obtained by an optimized phase-Doppler system in standard configuration, for a wide range of bubble sizes produced from single injectors in a quiescent environment. The two measuring techniques have yielded velocities and frequencies that are in very good agreement while the size of spherical bubbles was consistently measured by both methods. The phase-Doppler system was also used to size oblate-spheroidal bubbles moving with their equatorial plane parallel to the scattering plane, yielding measurements reasonably close to the average radius of curvature of the bubbles in the neighborhood of the equatorial plane, as calculated from the video-imaging data. Both methods were used for detailed velocity measurements of the bubble-stream in the neighborhood of the injector tip. The observed bubble-velocity variation with the distance from the injector tip does not always display the usual increasing trend leading into the terminal velocity. When injection conditions are near the transition from discrete to jet injection mode and the bubbles are small, the latter decelerate into a terminal velocity due to direct interaction of successive bubbles at the injector tip. The measured terminal velocities of bubble-chains for a variety of bubble sizes and injection frequencies, are successfully predicted by using a far-field wake approximation to account for the drafting effect which is responsible for bubble-chain velocities higher than those of single bubbles.
20. Dynamics of diffusive bubble growth in magmas: Isothermal case
Prousevitch, A. A.; Sahagian, D. L.; Anderson, A. T.
1993-12-01
We have conducted a parametric study and developed a new cell model describing diffusion-induced growth of closely spaced bubbles in magmatic sytems. The model accounts for (1) the effects of advection of melt resulting from bubble growth, and its affect on the local concentration profile; (2) dynamic resistence of the viscous melt during diffusive growth; (3) diffusion of volatiles in response to evolving concentration gradients; (4) mass balance between dissolved volatiles and gas inside the bubble; (5) changes in the equilibrium saturation concentration at the bubble-melt interface; (6) total pressure within the bubble consisting of ambient, surface tension, and dynamic pressures. The results of this study reveal that bubble growth depends strongly on ambient pressure, volatile oversaturation in the melt, and diffusivity coefficients, but only weakly on bubble separation and inital bubble radius. Increased volatile oversaturation increases growth rate to the point at which it actually reduces time for complete bubble growth. This counterintuitive result is due to significant advective volatile flux toward the bubble interface during growth. Viscosity controls growth dynamics only for cases of high viscosity (greater than 10(exp 4) Pa s). The documentation of the evolution of gas fraction in the melt and bubble wall thickness as a function of time makes it possible to estimate bubble disruption thresholds which bear on volcanic eruption mechanisms. Model results can be applied to the larger-scale problem of magmatic degassing in terms of bubble coalescence, flotation and the development of foams in magma chambers and vent systems, and ultimately to the dynamics of eruption mechanisms.
1. Initiation of breakdown in strings of bubbles immersed in transformer oil and water: string orientation and proximity of bubbles
Babaeva, Natalia Yu; Tereshonok, Dmitry V.; Naidis, George V.; Smirnov, Boris M.
2016-01-01
We computationally investigated the properties of positive streamers propagating inside strings of bubbles filled with humid air at atmospheric pressure, immersed in liquids and aligned along the electric field or transversal to it. We show that orientation of the string and proximity of bubbles are crucial for the streamer formation and re-initiation in the neighboring bubbles. For the vertical string (aligned along the electric field) there is a small field depletion inside the bubbles due to mutual polarization compared to the field in an isolated bubble. As a result, in a vertical string the ‘streamer hopping’ is more sensitive to the bubble separation. The streamer hopping is observed only when the separation is smaller than 300 μm. Polarization of the horizontal string of bubbles results in higher electric field inside the bubbles as compared to that in an isolated bubble. In this case, ‘streamer hopping’ is observed for the bubble separation 500 μm or larger. We also investigated the arrays of five and nine bubbles and showed that the enhancement of the electric field and streamer development depend on how many field depleting poles or field enhancing equators are in close proximity to the particular bubble.
2. Effect of static pressure on acoustic energy radiated by cavitation bubbles in viscous liquids under ultrasound.
PubMed
Yasui, Kyuichi; Towata, Atsuya; Tuziuti, Toru; Kozuka, Teruyuki; Kato, Kazumi
2011-11-01
The effect of static pressure on acoustic emissions including shock-wave emissions from cavitation bubbles in viscous liquids under ultrasound has been studied by numerical simulations in order to investigate the effect of static pressure on dispersion of nano-particles in liquids by ultrasound. The results of the numerical simulations for bubbles of 5 μm in equilibrium radius at 20 kHz have indicated that the optimal static pressure which maximizes the energy of acoustic waves radiated by a bubble per acoustic cycle increases as the acoustic pressure amplitude increases or the viscosity of the solution decreases. It qualitatively agrees with the experimental results by Sauter et al. [Ultrason. Sonochem. 15, 517 (2008)]. In liquids with relatively high viscosity (∼200 mPa s), a bubble collapses more violently than in pure water when the acoustic pressure amplitude is relatively large (∼20 bar). In a mixture of bubbles of different equilibrium radius (3 and 5 μm), the acoustic energy radiated by a 5 μm bubble is much larger than that by a 3 μm bubble due to the interaction with bubbles of different equilibrium radius. The acoustic energy radiated by a 5 μm bubble is substantially increased by the interaction with 3 μm bubbles. PMID:22087995
3. Magma mixing enhanced by bubble segregation
Wiesmaier, S.; Morgavi, D.; Renggli, C. J.; Perugini, D.; De Campos, C. P.; Hess, K.-U.; Ertel-Ingrisch, W.; Lavallée, Y.; Dingwell, D. B.
2015-08-01
In order to explore the materials' complexity induced by bubbles rising through mixing magmas, bubble-advection experiments have been performed, employing natural silicate melts at magmatic temperatures. A cylinder of basaltic glass was placed below a cylinder of rhyolitic glass. Upon melting, bubbles formed from interstitial air. During the course of the experimental runs, those bubbles rose via buoyancy forces into the rhyolitic melt, thereby entraining tails of basaltic liquid. In the experimental run products, these plume-like filaments of advected basalt within rhyolite were clearly visible and were characterised by microCT and high-resolution EMP analyses. The entrained filaments of mafic material have been hybridised. Their post-experimental compositions range from the originally basaltic composition through andesitic to rhyolitic composition. Rheological modelling of the compositions of these hybridised filaments yield viscosities up to 2 orders of magnitude lower than that of the host rhyolitic liquid. Importantly, such lowered viscosities inside the filaments implies that rising bubbles can ascend more efficiently through pre-existing filaments that have been generated by earlier ascending bubbles. MicroCT imaging of the run products provides textural confirmation of the phenomenon of bubbles trailing one another through filaments. This phenomenon enhances the relevance of bubble advection in magma mixing scenarios, implying as it does so, an acceleration of bubble ascent due to the decreased viscous resistance facing bubbles inside filaments and yielding enhanced mass flux of mafic melt into felsic melt via entrainment. In magma mixing events involving melts of high volatile content, bubbles may be an essential catalyst for magma mixing. Moreover, the reduced viscosity contrast within filaments implies repeated replenishment of filaments with fresh end-member melt. As a result, complex compositional gradients and therefore diffusion systematics can be
4. Morphology of Two-Phase Layers with Large Bubbles
Vékony, Klára; Kiss, László I.
2010-10-01
The understanding of formation and movement of bubbles nucleated during aluminum reduction is essential for a good control of the electrolysis process. In our experiments, we filmed and studied the formation of a bubble layer under the anode in a real-size air-water electrolysis cell model. The maximum height of the bubbles was found to be up to 2 cm because of the presence of the so-called Fortin bubbles. Also, the mean height of the bubble layer was found to be much higher than published previously. The Fortin bubbles were investigated more closely, and their shape was found to be induced by a gravity wave formed at the gas-liquid interface. In addition, large bubbles were always observed to break up into smaller parts right before escaping from under the anode. This breakup and escape led to a large momentum transfer in the bath.
5. Rheology of bubble-bearing magmas
Lejeune, A. M.; Bottinga, Y.; Trull, T. W.; Richet, P.
1999-02-01
The physical effects of air or argon bubbles on the rheology of a calcium aluminosilicate melt have been measured at temperatures ranging from 830° to 960°C, at 1 bar pressure. The melt composition is SiO 2:64, Al 2O 3:23, and CaO:13 (wt%), while bubble volume fractions are: 0, 0.06, 0.13, 0.32, 0.41 and 0.47. Measured Newtonian viscosities range from 10 10 to 10 14 dPa s. Melts with bubble fractions of 0.06 and 0.13 show with increasing temperature ( T) an increasing relative viscosity for T < 850°C. However at T > 850°C, for all bubble fractions the viscosity decreases markedly with temperature. The observed maximum decrease of the relative viscosity is 75% for a bubble fraction of 0.47 at 907°C. At all bubble fractions the viscosity is independent of the applied stress, which ranged from 11 to 677 bars. No clear indications were observed of non-Newtonian rheological behavior. Under our experimental conditions the relative viscosity of the two phase liquid depends primarily on the bubble fraction. Physical and volcanological implications of these measurements are discussed.
6. Heat transfer and bubble dynamics in slurry bubble columns for Fischer-Tropsch clean alternative energy
Wu, Chengtian
With the increasing demand for alternative energy resources, the Fischer-Tropsch (FT) process that converts synthesis gas into clean liquid fuels has attracted more interest from the industry. Slurry bubble columns are the most promising reactors for FT synthesis due to their advantages over other reactors. Successful operation, design, and scale-up of such reactors require detailed knowledge of hydrodynamics, bubble dynamics, and transport characteristics. However, most previous studies have been conducted at ambient pressure or covered only low superficial gas velocities. The objectives of this study were to experimentally investigate the heat transfer coefficient and bubble dynamics in slurry bubble columns at conditions that can mimic FT conditions. The air-C9C 11-FT catalysts/glass beads systems were selected to mimic the physical properties of the gas, liquid, and solid phases at commercial FT operating conditions. A heat transfer coefficient measurement technique was developed, and for the first time, this technique was applied in a pilot scale (6-inch diameter) high pressure slurry bubble column. The effects of superficial gas velocity, pressure, solids loading, and liquid properties on the heat transfer coefficients were investigated. Since the heat transfer coefficient can be affected by the bubble properties (Kumar et al., 1992), in this work bubble dynamics (local gas holdup, bubble chord length, apparent bubble frequency, specific interfacial area, and bubble velocity) were studied using the improved four-point optical probe technique (Xue et al., 2003; Xue, 2004). Because the four-point optical technique had only been successfully applied in a churn turbulent flow bubble column (Xue, 2004), this technique was first assessed in a small scale slurry bubble column in this study. Then the bubble dynamics were studied at the same conditions as the heat transfer coefficient investigation in the same pilot scale column. The results from four-point probe
7. Optical absorption properties of electron bubbles and experiments on monitoring individual electron bubbles in liquid helium
Guo, Wei
When a free electron is injected into liquid helium, it forms a microscopic bubble essentially free of helium atoms, which is referred to as an electron bubble. It represents a fine example of a quantum-mechanical particle confined in a potential well. In this dissertation, we describe our studies on bubble properties, especially the optical absorption properties of ground state electron bubbles and experiments on imaging individual electron bubbles in liquid helium. We studied the effect of zero-point and thermal fluctuations on the shape of ground state electron bubbles in liquid helium. The results are used to determine the line shape for the 1S to 1P optical transition. The calculated line shape is in very good agreement with the experimental measurements of Grimes and Adams. For 1S to 2P transition, the obtained transition line width agrees well with the measured data of Zipfel over a range of pressure up to 15 bars. Fluctuations in the bubble shape also make other "unallowed" transitions possible. The transition cross-sections from the 1S state to the 1D and 2D states are calculated with magnitude approximately two orders smaller than that of the 1S to 1P and 2P transitions. In our electron bubble imaging experiments, a planar ultrasonic transducer was used to generate strong sound wave pulse in liquid helium. The sound pulse passed through the liquid so as to produce a transient negative pressure over a large volume (˜ 1 cm3). An electron bubble that was passed by the sound pulse exploded for a fraction of a microsecond and grew to have a radius of around 10 microns. While the bubble had this large size it was illuminated with a flash lamp and its position was recorded. In this way, we can determine its position. Through the application of a series of sound pulses, we can then take images along the track of individual electrons. The motion of individual electron bubbles has been successfully monitored. Interesting bubble tracks that may relate to electrons
8. Steady bubble rise and deformation in Newtonian and viscoplastic fluids and conditions for bubble entrapment
Tsamopoulos, J.; Dimakopoulos, Y.; Chatzidai, N.; Karapetsas, G.; Pavlidis, M.
We examine the buoyancy-driven rise of a bubble in a Newtonian or a viscoplastic fluid assuming axial symmetry and steady flow. Bubble pressure and rise velocity are determined, respectively, by requiring that its volume remains constant and its centre of mass remains fixed at the centre of the coordinate system. The continuous constitutive model suggested by Papanastasiou is used to describe the viscoplastic behaviour of the material. The flow equations are solved numerically using the mixed finite-element/Galerkin method. The nodal points of the computational mesh are determined by solving a set of elliptic differential equations to follow the often large deformations of the bubble surface. The accuracy of solutions is ascertained by mesh refinement and predictions are in very good agreement with previous experimental and theoretical results for Newtonian fluids. We determine the bubble shape and velocity and the shape of the yield surfaces for a wide range of material properties, expressed in terms of the Bingham Bn=tau_y(*}/rho({*}g^{*)) R_b(*) Bond Bo =rho(*}g({*)) R_b({*) 2}/gamma(*) and Archimedes Ar=rho(*2}g({*)) R_b(*3}/mu_o({*2)) numbers, where *o the viscosity, *y the yield stress of the material, g* the gravitational acceleration and R*b the radius of a spherical bubble of the same volume. If the fluid is viscoplastic, the material will not be deforming outside a finite region around the bubble and, under certain conditions, it will not be deforming either behind it or around its equatorial plane in contact with the bubble. As Bn increases, the yield surfaces at the bubble equatorial plane and away from the bubble merge and the bubble becomes entrapped. When Bo is small and the bubble cannot deform from the spherical shape the critical Bn is 0.143, i.e. it is a factor of 3/2 higher than the critical Bn for the entrapment of a solid sphere in a Bingham fluid, in direct correspondence with the 3/2 higher terminal velocity of a bubble over that of a sphere
9. Bubble Manipulation by Self Organization of Bubbles inside Ultrasonic Wave
Yamakoshi, Yoshiki; Koganezawa, Masato
2005-06-01
Microbubble manipulation using ultrasonic waves is a promising technology in the fields of future medicine and biotechnology. For example, it is considered that bubble trapping using ultrasonic waves may play an important role in drug or gene delivery systems in order to trap the drugs or genes in the diseased tissue. Usually, when bubbles are designed so that they carry payloads, such as drug or gene, they tend to be harder than free bubbles. These hard bubbles receive a small acoustic radiation force, which is not sufficient for bubble manipulation. In this paper, a novel method of microbubble manipulation using ultrasonic waves is proposed. This method uses seed bubbles in order to manipulate target bubbles. When the seed bubbles are introduced into the ultrasonic wave field, they start to oscillate to produce a bubble aggregation of a certain size. Then the target bubbles are introduced, the target bubbles attach around the seed bubbles producing a bubble mass with bilayers (inner layer: seed bubbles, outer layer: target bubbles). The target bubbles are manipulated as a bilayered bubble mass. Basic experiments are carried out using polyvinyl chloride (PVC) shell bubbles. No target bubbles are trapped when only the target bubbles are introduced. However, they are trapped if the seed bubbles are introduced in advance.
10. Diamagnetic "bubble" equilibria in linear traps
Beklemishev, A. D.
2016-08-01
The plasma equilibrium in a linear trap at β ≈ 1 (or above the mirror-instability threshold) under the topology-conservation constraint evolves into a kind of diamagnetic "bubble." This can take two forms: either the plasma body greatly expands in radius while containing the same magnetic flux, or, if the plasma radius is limited, the plasma distribution across flux-tubes changes, so that the same cross-section contains a greatly reduced flux. If the magnetic field of the trap is quasi-uniform around its minimum, the bubble can be made roughly cylindrical, with radius much larger than the radius of the corresponding vacuum flux-tube, and with non-paraxial ends. Then the effective mirror ratio of the diamagnetic trap becomes very large, but the cross-field transport increases. The confinement time can be found from solution of the system of equilibrium and transport equations and is shown to be τ E ≈ √{ τ ∥ τ ⊥ } . If the cross-field confinement is not too degraded by turbulence, this estimate in principle allows construction of relatively compact fusion reactors with lengths in the range of a few tens of meters. In many ways, the described diamagnetic confinement and the corresponding reactor parameters are similar to those claimed by the field-reversed configurations.
11. Laser differential confocal radius measurement.
PubMed
Zhao, Weiqian; Sun, Ruoduan; Qiu, Lirong; Sha, Dingguo
2010-02-01
A new laser differential confocal radius measurement (DCRM) is proposed for high precision measurement of radius. Based on the property of an axial intensity curve that the absolute zero precisely corresponds to the focus of the objective in a differential confocal system (DCS), DCRM uses the zero point of the DCS axial intensity curve to precisely identify the cat's-eye and confocal positions of the test lens, and measures the accurate distance between the two positions to achieve the high-precision measurement of radius of curvature (ROC). In comparison with the existing measurement methods, DCRM proposed has a high measurement precision, a strong environmental anti-interference capability and a low cost. The theoretical analyses and preliminary experimental results indicate that DCRM has a relative measurement error of better than 5 ppm. PMID:20174065
12. Bubble bursting as an aerosol generation mechanism during an oil spill in the deep-sea environment: molecular dynamics simulations of oil alkanes and dispersants in atmospheric air/salt water interfaces.
PubMed
Liyana-Arachchi, Thilanga P; Zhang, Zenghui; Ehrenhauser, Franz S; Avij, Paria; Valsaraj, Kalliat T; Hung, Francisco R
2014-01-01
Potential of mean force (PMF) calculations and molecular dynamics (MD) simulations were performed to investigate the properties of oil n-alkanes [i.e., n-pentadecane (C15), n-icosane (C20) and n-triacontane (C30)], as well as several surfactant species [i.e., the standard anionic surfactant sodium dodecyl sulfate (SDS), and three model dispersants similar to the Tween and Span species present in Corexit 9500A] at air/salt water interfaces. This study was motivated by the 2010 Deepwater Horizon (DWH) oil spill, and our simulation results show that, from the thermodynamic point of view, the n-alkanes and the model dispersants have a strong preference to remain at the air/salt water interface, as indicated by the presence of deep free energy minima at these interfaces. The free energy minimum of these n-alkanes becomes deeper as their chain length increases, and as the concentration of surfactant species at the interface increases. The n-alkanes tend to adopt a flat orientation and form aggregates at the bare air/salt water interface. When this interface is coated with surfactants, the n-alkanes tend to adopt more tilted orientations with respect to the vector normal to the interface. These simulation results are consistent with the experimental findings reported in the accompanying paper [Ehrenhauser et al., Environ. Sci.: Processes Impacts 2013, in press, (DOI: 10.1039/c3em00390f)]. The fact that these long-chain n-alkanes show a strong thermodynamic preference to remain at the air/salt water interfaces, especially if these interfaces are coated with surfactants, makes these species very likely to adsorb at the surface of bubbles or droplets and be ejected to the atmosphere by sea surface processes such as whitecaps (breaking waves) and bubble bursting. Finally, the experimental finding that more oil hydrocarbons are ejected when Corexit 9500A is present in the system is consistent with the deeper free energy minima observed for the n-alkanes at the air/salt water
13. Nanoemulsions obtained via bubble-bursting at a compound interface
Feng, Jie; Roché, Matthieu; Vigolo, Daniele; Arnaudov, Luben N.; Stoyanov, Simeon D.; Gurkov, Theodor D.; Tsutsumanova, Gichka G.; Stone, Howard A.
2014-08-01
Bursting of bubbles at an air/liquid interface is a familiar occurrence relevant to foam stability, cell cultures in bioreactors and ocean-atmosphere mass transfer. In the latter case, bubble-bursting leads to the dispersal of sea-water aerosols in the surrounding air. Here we show that bubbles bursting at a compound air/oil/water-with-surfactant interface can disperse submicrometre oil droplets in water. Dispersal results from the detachment of an oil spray from the bottom of the bubble towards water during bubble collapse. We provide evidence that droplet size is selected by physicochemical interactions between oil molecules and the surfactants rather than by hydrodynamics. We demonstrate the unrecognized role that this dispersal mechanism may play in the fate of the sea surface microlayer and of pollutant spills by dispersing petroleum in the water column. Finally, our system provides an energy-efficient route, with potential upscalability, for applications in drug delivery, food production and materials science.
14. Dynamics of two-dimensional bubbles
Piedra, Saúl; Ramos, Eduardo; Herrera, J. Ramón
2015-06-01
The dynamics of two-dimensional bubbles ascending under the influence of buoyant forces is numerically studied with a one-fluid model coupled with the front-tracking technique. The bubble dynamics are described by recording the position, shape, and orientation of the bubbles as functions of time. The qualitative properties of the bubbles and their terminal velocities are described in terms of the Eötvos (ratio of buoyancy to surface tension) and Archimedes numbers (ratio of buoyancy to viscous forces). The terminal Reynolds number result from the balance of buoyancy and drag forces and, consequently, is not an externally fixed parameter. In the cases that yield small Reynolds numbers, the bubbles follow straight paths and the wake is steady. A more interesting behavior is found at high Reynolds numbers where the bubbles follow an approximately periodic zigzag trajectory and an unstable wake with properties similar to the Von Karman vortex street is formed. The dynamical features of the motion of single bubbles are compared to experimental observations of air bubbles ascending in a water-filled Hele-Shaw cell. Although the comparison is not strictly valid in the sense that the effect of the lateral walls is not incorporated in the model, most of the dynamical properties observed are in good qualitative agreement with the numerical calculations. Hele-Shaw cells with different gaps have been used to determine the degree of approximation of the numerical calculation. It is found that for the relation between the terminal Reynolds number and the Archimedes number, the numerical calculations are closer to the observations of bubble dynamics in Hele-Shaw cells of larger gaps.
15. Dynamics of two-dimensional bubbles.
PubMed
Piedra, Saúl; Ramos, Eduardo; Herrera, J Ramón
2015-06-01
The dynamics of two-dimensional bubbles ascending under the influence of buoyant forces is numerically studied with a one-fluid model coupled with the front-tracking technique. The bubble dynamics are described by recording the position, shape, and orientation of the bubbles as functions of time. The qualitative properties of the bubbles and their terminal velocities are described in terms of the Eötvos (ratio of buoyancy to surface tension) and Archimedes numbers (ratio of buoyancy to viscous forces). The terminal Reynolds number result from the balance of buoyancy and drag forces and, consequently, is not an externally fixed parameter. In the cases that yield small Reynolds numbers, the bubbles follow straight paths and the wake is steady. A more interesting behavior is found at high Reynolds numbers where the bubbles follow an approximately periodic zigzag trajectory and an unstable wake with properties similar to the Von Karman vortex street is formed. The dynamical features of the motion of single bubbles are compared to experimental observations of air bubbles ascending in a water-filled Hele-Shaw cell. Although the comparison is not strictly valid in the sense that the effect of the lateral walls is not incorporated in the model, most of the dynamical properties observed are in good qualitative agreement with the numerical calculations. Hele-Shaw cells with different gaps have been used to determine the degree of approximation of the numerical calculation. It is found that for the relation between the terminal Reynolds number and the Archimedes number, the numerical calculations are closer to the observations of bubble dynamics in Hele-Shaw cells of larger gaps. PMID:26172798
16. Nonlinear Bubble Interactions in Acoustic Pressure Fields
NASA Technical Reports Server (NTRS)
Barbat, Tiberiu; Ashgriz, Nasser; Liu, Ching-Shi
1996-01-01
The systems consisting of a two-phase mixture, as clouds of bubbles or drops, have shown many common features in their responses to different external force fields. One of particular interest is the effect of an unsteady pressure field applied to these systems, case in which the coupling of the vibrations induced in two neighboring components (two drops or two bubbles) may result in an interaction force between them. This behavior was explained by Bjerknes by postulating that every body that is moving in an accelerating fluid is subjected to a 'kinetic buoyancy' equal with the product of the acceleration of the fluid multiplied by the mass of the fluid displaced by the body. The external sound wave applied to a system of drops/bubbles triggers secondary sound waves from each component of the system. These secondary pressure fields integrated over the surface of the neighboring drop/bubble may result in a force additional to the effect of the primary sound wave on each component of the system. In certain conditions, the magnitude of these secondary forces may result in significant changes in the dynamics of each component, thus in the behavior of the entire system. In a system containing bubbles, the sound wave radiated by one bubble at the location of a neighboring one is dominated by the volume oscillation mode and its effects can be important for a large range of frequencies. The interaction forces in a system consisting of drops are much smaller than those consisting of bubbles. Therefore, as a first step towards the understanding of the drop-drop interaction subject to external pressure fluctuations, it is more convenient to study the bubble interactions. This paper presents experimental results and theoretical predictions concerning the interaction and the motion of two levitated air bubbles in water in the presence of an acoustic field at high frequencies (22-23 KHz).
17. Electrowetting of soap bubbles
Arscott, Steve
2013-07-01
A proof-of-concept demonstration of the electrowetting-on-dielectric of a sessile soap bubble is reported here. The bubbles are generated using a commercial soap bubble mixture—the surfaces are composed of highly doped, commercial silicon wafers covered with nanometer thick films of Teflon®. Voltages less than 40 V are sufficient to observe the modification of the bubble shape and the apparent bubble contact angle. Such observations open the way to inter alia the possibility of bubble-transport, as opposed to droplet-transport, in fluidic microsystems (e.g., laboratory-on-a-chip)—the potential gains in terms of volume, speed, and surface/volume ratio are non-negligible.
18. The Investigation of the Effects of Gravity on Single Bubble Sonoluminescence
NASA Technical Reports Server (NTRS)
Dzikowicz, Ben; Thiessen, David B.; Marston, Philip
2000-01-01
In single bubble following it's rapid collapse each cycle of oscillation of an ultrasonic field. Since widely varying length and time scales affect the bubble dynamics and optical emission processes, it is difficult to anticipate the importance of the effects of gravity present for observations on earth. Our bubble is driven in an acoustically resonating cavity at it's first harmonic mode. The acoustical radiation pressure (Bjerknes force) will then keep it suspended in the center near the pressure antinode. When driven in a region where the diffusive processes balance the bubble it acts in a nonlinear but regular way, emitting a short (approx. 200ps) burst of light each acoustic cycle. Balancing the Bjerknes force with buoyancy, as in, we can see that the bubble should be displaced from the velocity node approximately 20m at normal gravity. Therefore, water flows past the bubble at the time of collapse. Gravitation also changes the ambient pressure at the bubble's location, as Delta.P = rho.g.h this gives a change of approximately -0.5% in our experiment when going from 1.8g to 0g. Studies of ambient pressure changes were also done in order to assess these effects. Inside a pressure sealed chamber a spherical glass cell is filled with distilled water which has been degassed to 120mmHg. A bubble is then trapped in the center and driven by a piezoelectric transducer at 32.2kHz attached to the side of the cell. An optical system is then set up to take strobbed video images along and light emission data simultaneously. Temperature, pressure, drive voltage, and listener voltage are also monitored. PMT output in Volts The radii of the bubbles for both experiment s are fit using the Rayleigh-Plesset equation and the acoustic drive amplitude and the ambient bubble radius are found. There is little change in the acoustic drive amplitude as we expect, since we are not varying the drive voltage. However. the ambient bubble radius goes up considerably. These changes
19. Optical measurements of gas bubbles in oil behind a cavitating micro-orifice flow
Iben, Uwe; Wolf, Fabian; Freudigmann, Hans-Arndt; Fröhlich, Jochen; Heller, Winfried
2015-06-01
In hydraulic systems, it is common for air release to occur behind valves or throttles in the form of bubbles. These air bubbles can affect the behavior and the performance of these systems to a substantial extent. In the paper, gas release in a liquid flow behind an orifice is analyzed by optical methods for various operation points. The bubbles are observed with a digital camera, and a detection algorithm based on the Hough transformation is used to determine their number and size. The appearance of gas bubbles is very sensitive to the inlet and outlet pressure of the orifice. Gas bubbles are only observed if choking cavitation occurs. An empirical relationship between an adjusted cavitation number and the appearance of gas release is presented. It is assumed that the observed bubbles contain mostly air. With the applied pressure differences, up to 30 % of the dissolved air was degassed in the form of bubbles.
20. Gas bubble detector
NASA Technical Reports Server (NTRS)
Mount, Bruce E. (Inventor); Burchfield, David E. (Inventor); Hagey, John M. (Inventor)
1995-01-01
A gas bubble detector having a modulated IR source focused through a bandpass filter onto a venturi, formed in a sample tube, to illuminate the venturi with modulated filtered IR to detect the presence of gas bubbles as small as 0.01 cm or about 0.004 in diameter in liquid flowing through the venturi. Means are provided to determine the size of any detected bubble and to provide an alarm in the absence of liquid in the sample tube.
1. Dynamics of bubble-bubble interaction in sheared low-viscosity magma imaged by X-ray computed micro-tomography
Helo, C.; Flaws, A.; Hess, K.-U.; Franz, A.; Clague, D. A.; Dingwell, D. B.
2012-04-01
X-ray computed tomography of vesicles in basaltic pyroclastic glass fragments has been used to investigate the syn-eruptive shear environment and resulting bubble-bubble interaction during mild pyroclastic eruptions in a mid-ocean ridge environment. We have imaged vesicles present in two different types of pyroclastic fragments produced by mildly explosive activity on Axial Seamount, limu o Pele, that is, thin glass films often described as bubble walls, and tube scoria fragments. Rapid quenching of the glass has prevented extensive bubble relaxation preserving the syn-eruptive geometry of the bubbles in these fragments. Isolated, ellipsoid-shaped vesicles in low-vesicular limu o Pele indicate deformation in a simple shear environment. Under these shear conditions higher vesiculated parts of the erupting magma show strong bubble-bubble interactions partially leading to coalscence and formation of tubular vesicles. These tubular vesicles can reach significant lengths, exceeding the dimensions of the small glass fragments (2 mm). Their unreformed radius can be more then one order of magnitude larger than that of the isolated vesicles in the limu o Pele fragments. We can distinguish two principle modes of interaction based on the relative orientation of the bubbles. Interaction along the sidewalls of two bubbles, and tip-to-tip interaction. At interdistances of less than a few tens of micrometre, interaction of the sidewalls results in deformation of the bubbles to more irregular shapes, with depressions caused by close, small bubbles or in some cases bubbles being partially mantled around tubular bubbles. This often leads to a more close packing of bubbles. At distances of less than a few microns, the melt films between the bubbles destabilize leading to coalescence. This mechanism appears to involve a bulging of the larger bubble into the smaller, followed by melt film rapture and coalescence. The complete digestion of one bubble by the other is the slow rate
2. The effect of viscosity, applied frequency and driven pressure on the laser induced bubble luminescence in water-sulfuric acid mixtures
2016-06-01
Production and oscillation of sonoluminescence bubbles by laser pulse in the presence of acoustic field in water and different concentrations of sulfuric acid are investigated. In the presence of acoustic field, the laser causes variable speed of sound, surface tension and density; and the host liquid acts as a compressible one and strongly affects the bubble's dynamics equations. The effect of various concentrations of sulfuric acid as a host liquid on the oscillation of bubble radius, bubble wall velocity and bubble interior temperature is studied. Furthermore, the effect of applied frequency on LI-SCBL in the presence of the acoustic field is investigated and an optimum sound wave frequency for the bubble oscillation and bubble interior temperature in pure water and SA is introduced. Based on the modification of RP equation, by applying the optimum frequency, the results indicate that the maximum bubble radius for LI-SCBL in the presence of the acoustic field is increased up to 7 ×10-4 m as this article presents, which is more than 40% improvement. This amount results in interior temperature of more than three times, from almost 5000 K in the previous works to almost 16 000 K in the present report. This is very similar to the experimental measurements for bubble radius induced by laser. Furthermore, the effects of driving pressure amplitudes on the bubble radius, the bubble interior temperature and the bubble wall velocity in different host liquids and in optimum frequency are investigated.
Yariv, Ehud; Shusser, Michael
2006-07-01
When a stationary bubble is exposed to an external temperature gradient, Marangoni stresses at the bubble surface result in fluid motion. A straightforward attempt to calculate the influence of this thermocapillary flow upon the temperature distribution fails to provide a well-behaved solution [Balasubramaniam and Subramanian, Phys. Fluids 16, 3131 (2004)]. This problem is revisited here using a regularization procedure which exploits the qualitative disparity in the long-range flow fields generated by a stationary bubble and a moving one. The regularization parameter is an (exponentially small) artificial bubble velocity, which reflects the inability of any asymptotic expansion to satisfy the condition of exact bubble equilibrium. The solution is obtained using asymptotic matching of two separate Reynolds-number expansions: an inner expansion, valid at the bubble neighborhood, and a remote outer expansion, valid far beyond the familiar Oseen region. This procedure provides a well-behaved solution, which is subsequently used to evaluate the convection-induced correction to the hydrodynamic force exerted on the bubble. The independence of that correction upon the artificial velocity confirms the adequacy of the regularization procedure to describe the stationary-bubble case. The ratio of the calculated force to that pertaining to the classical pure-conduction limit [Young, Goldstein, and Block, J. Fluid Mech. 6, 350 (1959)] is given by 1-Ma/8+o(Ma), where Ma is a radius-based Marangoni number.
Yariv, Ehud; Shusser, Michael
2006-11-01
When a stationary bubble is exposed to an external temperature gradient, Marangoni stresses at the bubble surface result in fluid motion. A straight-forward attempt to calculate the influence of this thermocapillary flow upon the temperature distribution fails to provide well-behaved solution [Balasubramaniam & Subramanian, Phys. Fluids 16, 3131 (2004)]. This paradox is resolved here using regularization procedure which exploits the qualitative disparity in the long-range flow fields generated by stationary bubble and moving one. The regularization parameter is an (exponentially small) artificial bubble velocity U, which reflects the inability of any asymptotic expansion to satisfy the condition of exact bubble equilibrium. The solution is obtained using asymptotic matching of two separate Reynolds-number expansions: an inner expansion, valid at the bubble neighborhood, and remote outer expansion, valid far beyond the familiar Oseen region. This procedure provides well-behaved solution, which is subsequently used to evaluate the convection-induced correction to the hydrodynamic force exerted on the bubble. The independence of that correction upon U confirms the adequacy of the regularization procdure to descibe the stationary-bubble case. The ratio of the calculated force to that pertaining to the classical pure-conduction limit [Young, Goldstein Block, J. Fluid Mech. 6, 350 (1959)] is given by 1 - Ma/8+ o(Ma), where Ma is radius-based Marangoni number.
5. Pinch-off Scaling Law of Soap Bubbles
Davidson, John; Ryu, Sangjin
2014-11-01
Three common interfacial phenomena that occur daily are liquid drops in gas, gas bubbles in liquid and thin-film bubbles. One aspect that has been studied for these phenomena is the formation or pinch-off of the drop/bubble from the liquid/gas threads. In contrast to the formation of liquid drops in gas and gas bubbles in liquid, thin-film bubble pinch-off has not been well documented. Having thin-film interfaces may alter the pinch-off process due to the limiting factor of the film thickness. We observed the pinch-off of one common thin-film bubble, soap bubbles, in order to characterize its pinch-off behavior. We achieved this by constructing an experimental model replicating the process of a human producing soap bubbles. Using high-speed videography and image processing, we determined that the minimal neck radius scaled with the time left till pinch-off, and that the scaling law exponent was 2/3, similar to that of liquid drops in gas.
6. Evolution of Vapor Bubbles Nucleation Sites in Low Gravity
NASA Technical Reports Server (NTRS)
Buyevich, Yu A.; Webbon, Bruce W.
1995-01-01
When liquid is expelled by a vapor bubble growing at a nucleation site on a superheated surface, a thin microlayer underneath the bubble is left behind. It is evaporated from the free microlayer surface that provides for bubble growth. The average thickness of the microlayer determining the evaporation rate increases with time if the latter does not exceed a threshold value associated with the burn-out crisis. The bubble is described as a spherical segment with its flattened part adjoining the microlayer. This introduces two independent variables - the radius of the spherical part of the bubble surface and the polar angle that defines the relative area of the flattened part. They are to be found out from a set of two strongly nonlinear equations resulting from mass and momentum conservation laws. The first one depends on both microlayer thickness and nonmonotonously changing bubble base area. The second involves two major factors favoring bubble detachment - the buoyancy and a force due to the initial momentum of vapor input into the bubble. The former force depends on gravity whereas the latter one does not. It is why the limiting regimes of bubble evolution that correspond to normal or moderately reduced gravity and to microgravity feature drastically different properties. In the first case, the buoyancy dominates and the bubble evolves in such a manner as to become a full sphere at a moment that can be viewed as that of detachment. The detachment volume grows as gravity decreases. In the second case, the buoyancy is negligible and the bubble stays near the surface, while its volume continues to increase for a sufficiently long time. The findings are discussed in connection with experimental data obtained under different gravity conditions, some unpublished experiments being included. They help to understand why the pool boiling heat transfer coefficient frequently increases as gravity falls down and eventually vanishes.
7. Nonlinear dynamic behavior of microscopic bubbles near a rigid wall
Suslov, Sergey A.; Ooi, Andrew; Manasseh, Richard
2012-06-01
The nonlinear dynamic behavior of microscopic bubbles near a rigid wall is investigated. Oscillations are driven by the ultrasonic pressure field that arises in various biomedical applications such as ultrasound imaging or targeted drug delivery. It is known that, when bubbles approach a blood-vessel wall, their linear dynamic response is modified. This modification may be very useful for real-time detection of bubbles that have found targets; in future therapeutic technologies, it may be useful for controlled release of medical agents encapsulating microbubbles. In this paper, the nonlinear response of microbubbles near a wall is studied. The Keller-Miksis-Parlitz equation is adopted, but modified to account for the presence of a rigid wall. This base model describes the time evolution of the bubble surface, which is assumed to remain spherical, and accounts for the effect of acoustic radiation losses owing to liquid compressibility in the momentum conservation. Two situations are considered: the base case of an isolated bubble in an unbounded medium, and a bubble near a rigid wall. In the latter case, the wall influence is modeled by including a symmetrically oscillating image bubble. The bubble dynamics is traced using a numerical solution of the model equation. Subsequently, Floquet theory is used to accurately detect the bifurcation point where bubble oscillations stop following the driving ultrasound frequency and undergo period-changing bifurcations. Of particular interest is the detection of the subcritical period-tripling and -quadrupling transition. The parametric bifurcation maps are obtained as functions of nondimensional parameters representing the bubble radius, the frequency and pressure amplitude of the driving ultrasound field, and the distance from the wall. It is shown that the presence of the wall generally stabilises the bubble dynamics, so that much larger values of the pressure amplitude are needed to generate nonlinear responses. Thus, a
8. Simulation of hydrogen bubble growth in tungsten by a hybrid model
Sang, Chaofeng; Sun, Jizhong; Bonnin, Xavier; Wang, L.; Wang, Dezhen
2015-08-01
A two dimensional hybrid code (HIIPC-MC) joining rate-theory and Monte Carlo (MC) methods is developed in this work. We evaluate the cascade-coalescence mechanism contribution to the bubble growth by MC. First, effects of the starting radius and solute deuterium concentration on the bubble growth are studied; then the impacts of the wall temperature and implantation ion flux on the bubble growth are assessed. The simulation indicates that the migration-coalescence of the bubbles and the high pressure inside the bubbles are the main driving forces for the bubble growth, and that neglect of the migration and coalescence would lead to an underestimation of the bubble growth or blistering.
9. Mass Transport Phenomena Between Bubbles and Dissolved Gases in Liquids Under Reduced Gravity Conditions
NASA Technical Reports Server (NTRS)
Dewitt, K. J.; Brockwell, J. L.
1985-01-01
The long term objective of the experiment is to observe the dissolution of isolated, immobile gas bubbles of specified size and composition in a solvent liquid of known concentration in the reduced gravity environment of earth orbit. Preliminary bubble dissolution experiment conducted both in the NASA Lewis 2.2 sec drop tower and in normal gravity using SO2 - Toluene system were not completely successful in their objective. The method of gas injection and lack of bubble interface stabiliy experienced due to the extreme solubility of SO in Toluene has the effects of changing the problem from that of bubble dissolution to one of bubble formation stability and subsequent dissolution in a liquid of unknown initial solute concentration. Current work involves further experimentation in order to refine the bubble injection system and to investigate the concept of having a bubble with a critical radius in a state of unstable equilibrium.
10. Gas Bubble Pinch-off in Viscous and Inviscid Liquids
Taborek, P.
2005-11-01
We have used high-speed video to analyze pinch-off of nitrogen gas bubbles in fluids with a wide range of viscosity. If the external fluid is highly viscous (ηext>100 cP), the radius is proportional to the time before break, τ, and decreases smoothly to zero. If the external fluid has low viscosity (ηext<10 cP), the neck radius scales as &1/2circ; until an instability develops in the gas bubble which causes the neck to rupture and tear apart. Finally, if the viscosity of the external fluid is in an intermediate range, an elongated thread is formed which breaks apart into micron-sized bubbles. 100,000 frame-per-second videos will be presented which illustrate each of these flow regimes.
11. Electrical breakdown of a bubble in a water-filled capillary
SciTech Connect
Bruggeman, P.J.; Leys, C.A.; Vierendeels, J. A.
2006-06-01
In this Communication, the electrical breakdown of a static bubble in a water-filled capillary generated in a dc electrical field is studied. We present experimental results which indicate that the liquid layer between capillary and bubble wall can have an important influence on the breakdown mechanism of the bubble. The breakdown electrical field (atmospheric pressure) without a liquid layer in a (vapor) bubble is 18 kV/cm. When a liquid layer is present, the electrical breakdown of an air bubble is observed at electrical fields typically two times smaller. Local plasma formation is observed in this case possibly due to bubble deformation.
12. Detached eddy simulations of Taylor bubbles rising in stagnant liquid columns
Shaban, Hassan; Tavoularis, Stavros
2015-11-01
The rise of a single air Taylor bubble in a vertical circular tube filled with stagnant water was investigated numerically using the Volume Of Fluid (VOF) method to model the phase distribution and the Detached Eddy Simulation (DES) method for turbulence modelling. The predictions were in good quantitative agreement with previous experimental results. The simulation results provided insight into bubble shedding in the wake of the Taylor bubble, frictional pressure drop along the tube and scalar dispersion caused by the passage of the Taylor bubble. The interaction between adjacent Taylor bubbles and the process of Taylor bubble coalescence were also examined in detail. Supported by NSERC and UNENE.
13. Prospects for bubble fusion
SciTech Connect
Nigmatulin, R.I.; Lahey, R.T. Jr.
1995-09-01
In this paper a new method for the realization of fusion energy is presented. This method is based on the superhigh compression of a gas bubble (deuterium or deuterium/thritium) in heavy water or another liquid. The superhigh compression of a gas bubble in a liquid is achieved through forced non-linear, non-periodic resonance oscillations using moderate amplitudes of forcing pressure. The key feature of this new method is a coordination of the forced liquid pressure change with the change of bubble volume. The corresponding regime of the bubble oscillation has been called {open_quotes}basketball dribbling (BD) regime{close_quotes}. The analytical solution describing this process for spherically symmetric bubble oscillations, neglecting dissipation and compressibility of the liquid, has been obtained. This solution shown no limitation on the supercompression of the bubble and the corresponding maximum temperature. The various dissipation mechanisms, including viscous, conductive and radiation heat losses have been considered. It is shown that in spite of these losses it is possible to achieve very high gas bubble temperatures. This because the time duration of the gas bubble supercompression becomes very short when increasing the intensity of compression, thus limiting the energy losses. Significantly, the calculated maximum gas temperatures have shown that nuclear fusion may be possible. First estimations of the affect of liquid compressibility have been made to determine possible limitations on gas bubble compression. The next step will be to investigate the role of interfacial instability and breaking down of the bubble, shock wave phenomena around and in the bubble and mutual diffusion of the gas and the liquid.
14. A 3D Bubble Merger Model for RTI Mixing
Cheng, Baolian
2015-11-01
In this work we present a model for the merger processes of bubbles at the edge of an unstable acceleration driven mixing layer. Steady acceleration defines a self-similar mixing process, with a time-dependent inverse cascade of structures of increasing size. The time evolution is itself a renormalization group evolution. The model predicts the growth rate of a Rayleigh-Taylor chaotic fluid-mixing layer. The 3-D model differs from the 2-D merger model in several important ways. Beyond the extension of the model to three dimensions, the model contains one phenomenological parameter, the variance of the bubble radii at fixed time. The model also predicts several experimental numbers: the bubble mixing rate, the mean bubble radius, and the bubble height separation at the time of merger. From these we also obtain the bubble height to the radius aspect ratio, which is in good agreement with experiments. Applications to recent NIF and Omega experiments will be discussed. This work was performed under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under Contract No. W-7405-ENG-36.
15. Electric Field Effect on Bubble Detachment in Variable Gravity Environment
NASA Technical Reports Server (NTRS)
Iacona, Estelle; Herman, Cila; Chang, Shinan
2003-01-01
The subject of the present study, the process of bubble detachment from an orifice in a plane surface, shows some resemblance to bubble departure in boiling. Because of the high heat transfer coefficients associated with phase change processes, boiling is utilized in many industrial operations and is an attractive solution to cooling problems in aerospace engineering. In terrestrial conditions, buoyancy is responsible for bubble removal from the surface. In space, the gravity level being orders of magnitude smaller than on earth, bubbles formed during boiling remain attached at the surface. As a result, the amount of heat removed from the heated surface can decrease considerably. The use of electric fields is proposed to control bubble behavior and help bubble removal from the surface on which they form. The objective of the study is to investigate the behavior of individual air bubbles injected through an orifice into an electrically insulating liquid under the influence of a static electric field. Bubble cycle life were visualized in terrestrial conditions and for several reduced gravity levels. Bubble volume, dimensions and contact angle at detachment were measured and analyzed for different parameters as gravity level and electric field magnitude. Situations were considered with uniform or non-uni form electric field. Results show that these parameters significantly affect bubble behavior, shape, volume and dimensions.
16. Gases in Tektite Bubbles.
PubMed
O'keefe, J A; Lowman, P D; Dunning, K L
1962-07-20
Spectroscopic analysis of light produced by electrodeless discharge in a tektite bubble showed the main gases in the bubble to be neon, helium, and oxygen. The neon and helium have probably diffused in from the atmosphere, while the oxygen may be atmospheric gas incorporated in the tektite during its formation. PMID:17801113
17. Evaporation, Boiling and Bubbles
ERIC Educational Resources Information Center
Goodwin, Alan
2012-01-01
Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The…
18. Clustering in bubbly liquids
Figueroa, Bernardo; Zenit, Roberto
2004-11-01
We are conducting experiments to determine the amount of clustering that occurs when small gas bubbles ascend in clean water. In particular, we are interested in flows for which the liquid motion around the bubbles can be described, with a certain degree of accuracy, using potential flow theory. This model is applicable for the case of bubbly liquids in which the Reynolds number is large and the Weber number is small. To clearly observe the formation of bubble clusters we propose the use of a Hele-Shaw-type channel. In this thin channel the bubbles cannot overlap in the depth direction, therefore the identification of bubble clusters cannot be misinterpreted. Direct video image analysis is performed to calculate the velocity and size of the bubbles, as well as the formation of clusters. Although the walls do affect the motion of the bubbles, the clustering phenomena does occur and has the same qualitative behavior as in fully three-dimensional flows. A series of preliminary measurements are presented. A brief discussion of our plans to perform PIV measurements to obtain the liquid velocity fields is also presented.
19. Cost versus Enrollment Bubbles
ERIC Educational Resources Information Center
Vedder, Richard K.; Gillen, Andrew
2011-01-01
The defining characteristic of a bubble is unsustainable growth that eventually reverses. Bubbles typically arise when uncertainty leads to unsustainable trends, and the authors argue that there are two areas in which higher education has experienced what appear to be unsustainable trends, namely, college costs (the costs to students, parents, and…
20. Let Them Blow Bubbles.
ERIC Educational Resources Information Center
Korenic, Eileen
1988-01-01
Describes a series of activities and demonstrations involving the science of soap bubbles. Starts with a recipe for bubble solution and gives instructions for several activities on topics such as density, interference colors, optics, static electricity, and galaxy formation. Contains some background information to help explain some of the effects.…
1. Multiscale Modeling of Cavitating Bubbly Flows
Ma, J.; Hsiao, C.-T.; Chahine, G. L.
2013-03-01
Modeling of cavitating bubbly flows is challenging due to the wide range of characteristic lengths of the physics at play: from micrometers (e.g., bubble nuclei radius) to meters (e.g., propeller diameter or sheet cavity length). To address this, we present here a multiscale approach which integrates a Discrete Bubble Model for dispersed microbubbles and a level set N-S solver for macro cavities, along with a mesoscale transition model to bridge the two. This approach was implemented in 3DYNAFScopyright and used to simulate sheet-to-cloud cavitation over a hydrofoil. The hybrid model captures well the full cavitation process starting from free field nuclei and nucleation from solid surfaces. In low pressure region of the foil small nuclei are seen to grow large and eventually merge to form a large scale sheet cavity. A reentrant jet forms under the cavity, travels upstream, and breaks it, resulting in a bubble cloud of a large amount of microbubbles as the broken pockets shrink and travel downstream. This is in good agreement with experimental observations based of sheet lengths and frequency of lift force oscillation. DOE-SBIR, ONR (monitored by Dr. Ki-Han Kim)
2. EXPERIMENTAL BUBBLE FORMATION IN A LARGE SCALE SYSTEM FOR NEWTONIAN AND NONNEWTONIAN FLUIDS
SciTech Connect
Leishear, R; Michael Restivo, M
2008-06-26
The complexities of bubble formation in liquids increase as the system size increases, and a photographic study is presented here to provide some insight into the dynamics of bubble formation for large systems. Air was injected at the bottom of a 28 feet tall by 30 inch diameter column. Different fluids were subjected to different air flow rates at different fluid depths. The fluids were water and non-Newtonian, Bingham plastic fluids, which have yield stresses requiring an applied force to initiate movement, or shearing, of the fluid. Tests showed that bubble formation was significantly different in the two types of fluids. In water, a field of bubbles was formed, which consisted of numerous, distributed, 1/4 to 3/8 inch diameter bubbles. In the Bingham fluid, large bubbles of 6 to 12 inches in diameter were formed, which depended on the air flow rate. This paper provides comprehensive photographic results related to bubble formation in these fluids.
3. Coalescence In Draining Foams Made of Very Small Bubbles.
PubMed
Briceño-Ahumada, Zenaida; Drenckhan, Wiebke; Langevin, Dominique
2016-03-25
We studied the stability of foams containing small bubbles (radius ≲ 50 μm). The foams are made from aqueous surfactant solutions containing various amounts of glycerol. The foams start breaking at their top, when the liquid volume fraction has decreased sufficiently during liquid drainage. Unlike in foams with larger bubbles, the liquid fraction at which the foam destabilizes is surprisingly high. In order to interpret this observation we propose that film rupture occurs during reorganization events (T1) induced by bubble coarsening, which is particularly rapid in the case of small bubbles. New films are therefore formed rapidly and if their thickness is too small, they cannot be sufficiently covered by surfactant and they break. Using literature data for the duration of T1 events and the thickness of the new films, we show that this mechanism is consistent with the behavior of the foams studied. PMID:27058106
4. Coalescence In Draining Foams Made of Very Small Bubbles
Briceño-Ahumada, Zenaida; Drenckhan, Wiebke; Langevin, Dominique
2016-03-01
We studied the stability of foams containing small bubbles (radius ≲ 50 μ m ). The foams are made from aqueous surfactant solutions containing various amounts of glycerol. The foams start breaking at their top, when the liquid volume fraction has decreased sufficiently during liquid drainage. Unlike in foams with larger bubbles, the liquid fraction at which the foam destabilizes is surprisingly high. In order to interpret this observation we propose that film rupture occurs during reorganization events (T 1 ) induced by bubble coarsening, which is particularly rapid in the case of small bubbles. New films are therefore formed rapidly and if their thickness is too small, they cannot be sufficiently covered by surfactant and they break. Using literature data for the duration of T 1 events and the thickness of the new films, we show that this mechanism is consistent with the behavior of the foams studied.
5. On the possibility of diffusionally driven oscillations in two component gas bubbles in fluids
NASA Technical Reports Server (NTRS)
Weinberg, Michael C.
1986-01-01
The problem of an isolated, stationary, two-component gas bubble in a fluid is analyzed. The appropriate governing equations, and an approximate version of these equations, for this model system are reviewed. The qualitative differences in bubble dissolution behavior between single- and two-component gas bubbles are elucidated. In particular, it is demonstrated that in the latter case the gas bubble radius may exhibit extrema as a function of time for certain values of the controlling parameters. The conditions under which these extrema may occur, and the maximum number of extrema which are permitted are elucidated.
6. Transverse Electron Motion and Multiple Electron Injection in Blowout Bubble of Laser Wakefield Accelerator
Matsuoka, T.; McGuffey, C.; Cummings, P. G.; Horovitz, Y.; Dollar, F.; Schumaker, W.; Chvykov, V.; Kalintchenko, G.; Rousseau, P.; Yanovsky, V.; Bulanov, S. S.; Thomas, A. G. R.; Maksimchuk, A.; Krushelnick, K.
2010-11-01
An analytical formula for electron motion in a spherical bubble was compared with data from electron acceleration experiments using the HERCULES laser system showing reasonable agreement. This also provides evidence for continuous injection of electrons into the bubble with multiple bunches in the bubble separated both transversely and longitudinally. The only free parameter in the analytical model was radius of the bubble (rb) which was found to be close to the matched spot size for self focusing. The RMS electron beam divergence is found to increase with bunch charge also suggesting tradeoff between beam divergence and photon number in applications for such beams as an x-ray source.
7. Bubbles, Bubbles: Integrated Investigations with Floating Spheres
ERIC Educational Resources Information Center
Reeder, Stacy
2007-01-01
In this article, the author describes integrated science and mathematics activities developed for fourth-grade students to explore and investigate three-dimensional geometric shapes, Bernoulli's principle, estimation, and art with and through bubbles. Students were engaged in thinking and reflection on the questions their teachers asked and were…
8. Tribonucleation of bubbles
PubMed Central
Wildeman, Sander; Lhuissier, Henri; Sun, Chao; Lohse, Detlef; Prosperetti, Andrea
2014-01-01
We report on the nucleation of bubbles on solids that are gently rubbed against each other in a liquid. The phenomenon is found to depend strongly on the material and roughness of the solid surfaces. For a given surface, temperature, and gas content, a trail of growing bubbles is observed if the rubbing force and velocity exceed a certain threshold. Direct observation through a transparent solid shows that each bubble in the trail results from the early coalescence of several microscopic bubbles, themselves detaching from microscopic gas pockets forming between the solids. From a detailed study of the wear tracks, with atomic force and scanning electron microscopy imaging, we conclude that these microscopic gas pockets originate from a local fracturing of the surface asperities, possibly enhanced by chemical reactions at the freshly created surfaces. Our findings will be useful either for preventing undesired bubble formation or, on the contrary, for “writing with bubbles,” i.e., creating controlled patterns of microscopic bubbles. PMID:24982169
9. A modelling and experimental study of the bubble trajectory in a non-Newtonian crystal suspension
Hassan, N. M. S.; Khan, M. M. K.; Rasul, M. G.
2010-12-01
This paper presents an experimental and computational study of air bubbles rising in a massecuite-equivalent non-Newtonian crystal suspension. The bubble trajectory inside the stagnant liquid of a 0.05% xanthan gum crystal suspension was investigated and modelled using the computational fluid dynamics (CFD) model to gain an insight into the bubble flow characteristics. The CFD code FLUENT was used for numerical simulation, and the bubble trajectory calculations were performed through a volume of fluid (VOF) model. The influences of the Reynolds number (Re), the Weber number (We) and the bubble aspect ratio (E) on the bubble trajectory are discussed. The conditions for the bubbles' path oscillations are identified. The experimental results showed that the path instability for the crystal suspension was less rapid than in water. The trajectory analysis indicated that 5.76 mm diameter bubbles followed a zigzag motion in the crystal suspension. Conversely, the smaller bubbles (5.76 mm) followed a path of least horizontal movement and larger bubbles (21.21 mm) produced more spiral motion within the crystal suspension. Path instability occurred for bubbles of 15.63 and 21.21 mm diameter, and they induced both zigzag and spiral trajectories within the crystal suspension. At low Re and We, smaller bubbles (5.76 mm) produced a zigzag trajectory, whereas larger bubbles (15.63 and 21.21 mm) showed both zigzag and spiral trajectories at intermediate and moderately high Re and We in the crystal suspension. The simulation results illustrated that a repeating pattern of swirling vortices was created for smaller bubbles due to the unstable wake and unsteady flow of these bubbles. This is the cause of the smaller bubbles moving in a zigzag way. Larger bubbles showed two counter-rotating trailing vortices at the back of the bubble. These vortices induced a velocity component to the gas-liquid interface and caused a deformation. Hence, the larger bubbles produced a path transition.
10. Structure and dynamics of the wake of bubbles and its relevance for bubble interaction
Brücker, Christoph
1999-07-01
The flow in the wake of single and two interacting air bubbles freely rising in water is studied experimentally using digital-particle-image-velocimetry in combination with high-speed recording. The experiments focus on ellipsoidal bubbles of diameter of about 0.4-0.8 cm which show spiraling, zigzagging, and rocking motion during their rise in water, which was seeded with small tracer particles for flow visualization. Under counterflow conditions in the vertical channel, the bubbles are retained in the center of the observation region, which allows the wake oscillations and bubble interaction to be observed over several successive periods. By simultaneous diffuse illumination in addition to the light sheet, we were able to record both the path and shape oscillations of the bubble, as well as the wake structure in a horizontal and vertical cross section. The results show that the zigzagging motion is coupled to a regular generation and discharge of alternate oppositely oriented hairpin-like vortex structures. Associated with the wake oscillation, the bubble experiences a strong asymmetric deformation in the equatorial plane at the inversion points of the zigzag path. The zigzag motion is superimposed on a small lateral drift of the bubble, which implies the existence of a net lift force. This is explained by the observed different strength of the hairpin vortices in the zig and zag path; a seemingly familiar phenomenon was found in recent numerical results of the sphere wake flow. For spiraling bubbles the wake is approximately steady to an observer moving with the bubble. It consists of a twisted pair of streamwise vortex filaments which are wound in a helical path and are attached to the bubble base at an asymmetrical position. The minor axis of the bubble is tilted in the tangential plane as well as in the radial plane toward the spiral center. Due to the pressure field induced by the asymmetrically attached wake two components of the lift force exist, one that
11. Significance of viscoelastic effects on the rising of a bubble and bubble-to-bubble interaction
Fernandez, Arturo
2011-11-01
Numerical results for the rising of a bubble and the interaction between two bubbles in non-Newtonian fluids will be discussed. The computations are carried out using a multiscale method combining front-tracking with Brownian dynamics simulations. The evaluation of the material properties for the non-Newtonian fluid will be discussed firstly. The results from the computations of a single bubble show how elastic effects modify the deformation and rising of the bubble by pulling the tail of it. The relationship between the strength of the elastic forces and the discontinuity in the bubble terminal velocity, when plotted versus bubble volume, is also observed in the computations. The bubble-to-bubble interaction is dominated not only by elastic effects but also by the shear-thinning caused by the leading bubble, which leads the trailing bubble to accelerate faster and coalesce with the leading bubble.
DOEpatents
Webb, Brent J.; Coomes, Edmund P.
1988-12-06
A heat radiator useful for expelling waste heat from a power generating system aboard a space vehicle is disclosed. Liquid to be cooled is passed to the interior of a rotating bubble membrane radiator, where it is sprayed into the interior of the bubble. Liquid impacting upon the interior surface of the bubble is cooled and the heat radiated from the outer surface of the membrane. Cooled liquid is collected by the action of centrifical force about the equator of the rotating membrane and returned to the power system. Details regarding a complete space power system employing the radiator are given.
13. Dynamics of diffusive bubble growth and pressure recovery in a bubbly rhyolitic melt embedded in an elastic solid
USGS Publications Warehouse
Chouet, Bernard A.; Dawson, Phillip B.; Nakano, Masaru
2006-01-01
We present a model of gas exsolution and bubble expansion in a melt supersaturated in response to a sudden pressure drop. In our model, the melt contains a suspension of gas bubbles of identical sizes and is encased in a penny-shaped crack embedded in an elastic solid. The suspension is modeled as a three-dimensional lattice of spherical cells with slight overlap, where each elementary cell consists of a gas bubble surrounded by a shell of volatile-rich melt. The melt is then subjected to a step drop in pressure, which induces gas exsolution and bubble expansion, resulting in the compression of the melt and volumetric expansion of the crack. The dynamics of diffusion-driven bubble growth and volumetric crack expansion span 9 decades in time. The model demonstrates that the speed of the crack response depends strongly on volatile diffusivity in the melt and bubble number density and is markedly sensitive to the ratio of crack thickness to crack radius and initial bubble radius but is relatively insensitive to melt viscosity. The net drop in gas concentration in the melt after pressure recovery represents only a small fraction of the initial concentration prior to the drop, suggesting the melt may undergo numerous pressure transients before becoming significantly depleted of gases. The magnitude of pressure and volume recovery in the crack depends sensitively on the size of the input-pressure transient, becoming relatively larger for smaller-size transients in a melt containing bubbles with initial radii less than 10-5 m. Amplification of the input transient may be large enough to disrupt the crack wall and induce brittle failure in the rock matrix surrounding the crack. Our results provide additional basis for the interpretation of volume changes in the magma conduit under Popocatépetl Volcano during Vulcanian degassing bursts in its eruptive activity in April–May 2000.
14. Dynamics of a bubble bouncing at a compound interface
Feng, Jie; Muradoglu, Metin; Stone, Howard A.
2014-11-01
Bubbly flow is extensively involved in a wide range of technological applications, which generate a great demand for understanding of bubble physics. The collision, bouncing and coalescence of moving bubbles with liquid/gas and liquid/solid interfaces, as the first stage for the formation of foams and flotation aggregates, have been the subject of many studies, but there are still unanswered questions related to how the properties of the interface influence the dynamics. For example, Zawala et al. 2013 have tried to investigate how the kinetic energy of the bubble affects the liquid film drainage during the collision with an air-water interface. Inspired by Feng et al. 2014, we study the dynamics of an air bubble bouncing at a liquid/liquid/gas interface, in which a thin layer of oil is put on top of the water. The presence of the oil layer changes the interfacial properties and thus the entire process. Combined with direct numerical simulations, extensive experiments were carried out to investigate the effects of the oil layer thickness, oil viscosity, bubble size and initial impact velocity on the bouncing of the bubble at the compound interface. In addition, a mass-spring model is proposed to describe the bubble dynamics and interactions with the oil layer.
15. Stably Levitated Large Bubbles in Vertically Vibrating Liquids
O'Hern, Timothy; Shelden, Bion; Romero, Louis; Torczynski, John
2012-11-01
Vertical vibration of a liquid can cause small gas bubbles to move downward against the buoyancy force. Downward bubble motion is caused by the oscillating bubble volume (induced by the oscillating pressure field) interacting with the bubble drag force. The volume-drag asymmetry and the oscillating pressure gradient produce net downward bubble motion analogous to that caused by the Bjerknes force in high-frequency vibrations. Low-frequency (below 300 Hz) experiments demonstrate downward bubble motion over a range of vibration conditions, liquid properties, and pressure in the air above the free surface. Small bubbles deep in a quasi-two-dimensional test cell usually coalesce to form a much larger bubble that is stably levitated well below the free surface. The size and position of this levitated bubble can be controlled by varying the vibration conditions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
16. Frictional drag reduction in bubbly Couette-Taylor flow
Murai, Yuichi; Oiwa, Hiroshi; Takeda, Yasushi
2008-03-01
Frictional drag reduction due to the presence of small bubbles is investigated experimentally using a Couette-Taylor flow system; i.e., shear flow between concentric cylinders. Torque and bubble behavior are measured as a function of Reynolds number up to Re =5000 while air bubbles are injected constantly and rise through an array of vortical cells. Silicone oil is used to avoid the uncertain interfacial property of bubbles and to produce nearly monosized bubble distributions. The effect of drag reduction on sensitivity and power gain are assessed. The sensitivity exceeds unity at Re <2000, proving that the effect of the reduction in drag is greater than that of the reduction in mixture density. This is due to the accumulation of bubbles toward the rotating inner cylinder, which is little affected by turbulence. The power gain, which is defined by the power saving from the drag reduction per the pumping power of bubble injection, has a maximum value of O(10) at higher Re numbers around 2500. An image processing measurement shows this is because of the disappearance of azimuthal waves when the organized bubble distribution transforms from toroidal to spiral modes. Moreover, the axial spacing of bubble clouds expands during the transition, which results in an effective reduction in the momentum exchange.
17. Spectra of single-bubble sonoluminescence in water and glycerin-water mixtures
Gaitan, D. Felipe; Atchley, Anthony A.; Lewia, S. D.; Carlson, J. T.; Maruyama, X. K.; Moran, Michael; Sweider, Darren
1996-07-01
A single gas bubble, acoustically levitated in a standing-wave field and oscillating under the action of that field, can emit pulses of blue-white light with duration less than 50 ps. Measurements of the spectrum of this picosecond sonoluminescence with a scanning monochrometer are reported for air bubbles levitated in water and in glycerin-water mixtures. While the spectrum has been reported previously by others for air bubbles in water, the spectrum for air bubbles in water-glycerin mixtures has not. Expected emission lines from glycerin were conspicuously absent, suggesting a different mechanism for light production in single-bubble sonoluminescence. Other conclusions are the spectrum for air bubbles in water is consistent with that previously reported, the radiated energy decreases as the glycerin concentration increases, and the peak of the spectrum appears to shift to longer wavelengths for the water-glycerin mixtures.
18. Helium nano-bubble evolution in aging metal tritides.
SciTech Connect
Cowgill, Donald F.
2004-05-01
A continuum-scale, evolutionary model of helium (He) nano-bubble nucleation, growth and He release for aging bulk metal tritides is presented which accounts for major features of the experimental database. Bubble nucleation, modeled as self-trapping of interstitially diffusing He atoms, is found to occur during the first few days following tritium introduction into the metal and is sensitive to the He diffusivity and pairing energy. An effective helium diffusivity of 0.3 x 10{sup -16} cm{sup 2}/s at 300 K is required to generate the average bubble density of 5x 1017 bubbles/cm3 observed by transmission electron microscopy (TEM). Early bubble growth by dislocation loop punching with a l/radius bubble pressure dependence produces good agreement with He atomic volumes and bubble pressures determined from swelling data, nuclear magnetic resonance (NMR) measurements, and hydride pressure-composition-temperature (PCT) shifts. The model predicts that later in life neighboring bubble interactions may first lower the loop punching pressure through cooperative stress effects, then raise the pressure by partial blocking of loops. It also accounts for the shape of the bubble spacing distribution obtained from NMR data. This distribution is found to remain fixed with age, justifying the separation of nucleation and growth phases, providing a sensitive test of the growth formulation, and indicating that further significant bubble nucleation does not occur throughout life. Helium generated within the escape depth of surfaces and surface-connected porosity produces the low-level early helium release. Accelerated or rapid release is modeled as inter-bubble fracture using an average ligament stress criterion. Good agreement is found between the predicted onset of fracture and the observed He-metal ratio (HeM) for rapid He release from bulk palladium tritide. An examination of how inter-bubble fracture varies over the bubble spacing distribution shows that the critical Hem will be
19. Asymmetric motion of bubble in nematic liquid crystal induced by symmetry-broken evaporation
Kim, Sung-Jo; Lev, Bohdan; Kim, Jong-Hyun
2016-07-01
The size of air bubbles in nematic liquid crystals can be continuously decreased through the absorption of air molecules into the host liquid crystal. A bubble and its accompanying hyperbolic hedgehog point defect undergo a continuous asymmetric motion, while the bubble decreases in size. In this study, a mechanism is proposed to theoretically explain both the motion of the air bubble and the point defect observed experimentally. Anisotropic evaporation of air molecules may occur because of the symmetry breaking of the director configuration near the point defect. The motion of the center of the air bubble to the hyperbolic hedgehog point defect is induced by the anisotropic force due to evaporation of air molecules and Stokes drag force.
20. What's in a Bubble?
ERIC Educational Resources Information Center
Saunderson, Megan
2000-01-01
Describes a unit on detergents and bubbles that establishes an interest in the properties of materials and focuses on active learning involving both hands- and minds-on learning rather than passive learning. (ASK)
1. Blowing magnetic skyrmion bubbles
Jiang, Wanjun; Upadhyaya, Pramey; Zhang, Wei; Yu, Guoqiang; Jungfleisch, M. Benjamin; Fradin, Frank Y.; Pearson, John E.; Tserkovnyak, Yaroslav; Wang, Kang L.; Heinonen, Olle; te Velthuis, Suzanne G. E.; Hoffmann, Axel
2015-07-01
The formation of soap bubbles from thin films is accompanied by topological transitions. Here we show how a magnetic topological structure, a skyrmion bubble, can be generated in a solid-state system in a similar manner. Using an inhomogeneous in-plane current in a system with broken inversion symmetry, we experimentally “blow” magnetic skyrmion bubbles from a geometrical constriction. The presence of a spatially divergent spin-orbit torque gives rise to instabilities of the magnetic domain structures that are reminiscent of Rayleigh-Plateau instabilities in fluid flows. We determine a phase diagram for skyrmion formation and reveal the efficient manipulation of these dynamically created skyrmions, including depinning and motion. The demonstrated current-driven transformation from stripe domains to magnetic skyrmion bubbles could lead to progress in skyrmion-based spintronics.
2. Chemistry in Soap Bubbles.
ERIC Educational Resources Information Center
Lee, Albert W. M.; Wong, A.; Lee, H. W.; Lee, H. Y.; Zhou, Ning-Huai
2002-01-01
Describes a laboratory experiment in which common chemical gases are trapped inside soap bubbles. Examines the physical and chemical properties of the gases such as relative density and combustion. (Author/MM)
3. Bubble coalescence in magmas
NASA Technical Reports Server (NTRS)
Herd, Richard A.; Pinkerton, Harry
1993-01-01
The most important factors governing the nature of volcanic eruptions are the primary volatile contents, the ways in which volatiles exsolve, and how the resulting bubbles grow and interact. In this contribution we assess the importance of bubble coalescence. The degree of coalescence in alkali basalts has been measured using Image Analysis techniques and it is suggested to be a process of considerable importance. Binary coalescence events occur every few minutes in basaltic melts with vesicularities greater than around 35 percent.
4. Radius of curvature controlled mirror
DOEpatents
Neil, George R.; Rathke, John Wickham; Schultheiss, Thomas John; Shinn, Michelle D.; Dillon-Townes, Lawrence A.
2006-01-17
A controlled radius of curvature mirror assembly comprising: a distortable mirror having a reflective surface and a rear surface; and in descending order from the rear surface; a counter-distortion plate; a flow diverter having a flow diverter aperture at the center thereof; a flow return plate having a flow return aperture at the center thereof; a thermal isolation plate having a thermal isolation plate aperture at the center thereof and a flexible heater having a rear surface and a flexible heater aperture at the center thereof; a double walled tube defining a coolant feed chamber and a coolant return chamber; said coolant feed chamber extending to and through the flow diverter aperture and terminating at the counter-distortion plate and the coolant return chamber extending to and through the thermal isolation backplate and terminating at the flow diverter; and a coolant feed and a coolant return exit at the rear of said flexible heater.
5. Treatment of distal radius fractures.
PubMed
Lichtman, David M; Bindra, Randipsingh R; Boyer, Martin I; Putnam, Matthew D; Ring, David; Slutsky, David J; Taras, John S; Watters, William C; Goldberg, Michael J; Keith, Michael; Turkelson, Charles M; Wies, Janet L; Haralson, Robert H; Boyer, Kevin M; Hitchcock, Kristin; Raymond, Laura
2010-03-01
The clinical practice guideline is based on a systematic review of published studies on the treatment of distal radius fractures in adults. None of the 29 recommendations made by the work group was graded as strong; most are graded as inconclusive or consensus; seven are graded as weak. The remaining five moderate-strength recommendations include surgical fixation, rather than cast fixation, for fractures with postreduction radial shortening >3 mm, dorsal tilt >10 degrees , or intra-articular displacement or step-off >2 mm; use of rigid immobilization rather than removable splints for nonsurgical treatment; making a postreduction true lateral radiograph of the carpus to assess dorsal radial ulnar joint alignment; beginning early wrist motion following stable fixation; and recommending adjuvant treatment with vitamin C to prevent disproportionate pain. PMID:20190108
6. Clustering in Bubble Suspensions
Zenit, Roberto
2000-11-01
A monidisperse bubble suspension is studied experimentally for the limit in which the Weber number is small and the Reynolds number is large. For this regime the suspension can be modeled using potential flow theory to describe the dynamics of the interstitial fluid. Complete theoretical descriptions have been composed (Spelt and Sangani, 1998) to model the behavior of these suspensions. Bubble clustering is a natural instability that arises from the potential flow considerations, in which bubbles tend to align in horizontal rafts as they move upwards. The appearance of bubble clusters was recently corroborated experimentally by Zenit et al. (2000), who found that although clusters did appear, their strength was not as strong as the predictions. Experiments involving gravity driven shear flows are used to explain the nature of the clustering observed in these type of flows. Balances of the bubble phase pressure (in terms of a calculated diffusion coefficient) and the Maxwell pressure (from the potential flow description) are presented to predict the stability of the bubble suspension. The predictions are compared with experimental results.
7. Time-resolved imaging of electrical discharge development in underwater bubbles
Tu, Yalong; Xia, Hualei; Yang, Yong; Lu, Xinpei
2016-01-01
The formation and development of plasma in single air bubbles submerged in water were investigated. The difference in the discharge dynamics and the after-effects on the bubble were investigated using a 900 000 frame per second high-speed charge-coupled device camera. It was observed that depending on the position of the electrodes, the breakdown could be categorized into two modes: (1) direct discharge mode, where the high voltage and ground electrodes were in contact with the bubble, and the streamer would follow the shortest path and propagate along the axis of the bubble and (2) dielectric barrier mode, where the ground electrode was not in touch with the bubble surface, and the streamer would form along the inner surface of the bubble. The oscillation of the bubble and the development of instabilities on the bubble surface were also discussed.
8. Numerical simulation of cavitation bubble dynamics induced by ultrasound waves in a high frequency reactor.
PubMed
Servant, G; Caltagirone, J P; Gérard, A; Laborde, J L; Hita, A
2000-10-01
The use of high frequency ultrasound in chemical systems is of major interest to optimize chemical procedures. Characterization of an open air 477 kHz ultrasound reactor shows that, because of the collapse of transient cavitation bubbles and pulsation of stable cavitation bubbles, chemical reactions are enhanced. Numerical modelling is undertaken to determine the spatio-temporal evolution of cavitation bubbles. The calculus of the emergence of cavitation bubbles due to the acoustic driving (by taking into account interactions between the sound field and bubbles' distribution) gives a cartography of bubbles' emergence within the reactor. Computation of their motion induced by the pressure gradients occurring in the reactor show that they migrate to the pressure nodes. Computed bubbles levitation sites gives a cartography of the chemical activity of ultrasound. Modelling of stable cavitation bubbles' motion induced by the motion of the liquid gives some insight on degassing phenomena. PMID:11062879
9. Atmospheric-pressure microplasma in dielectrophoresis-driven bubbles for optical emission spectroscopy.
PubMed
Fan, Shih-Kang; Shen, Yan-Ting; Tsai, Ling-Pin; Hsu, Cheng-Che; Ko, Fu-Hsiang; Cheng, Yu-Ting
2012-10-01
The manipulation of bubbles and the ignition of microplasma within a 200 nL bubble at atmospheric pressure and in an inert silicone oil environment were achieved. Driven by dielectrophoresis (DEP), bubble generation, transportation, mixing, splitting, and expelling were demonstrated. This process facilitated the preparation of various bubbles with tuneable gas compositions. Different gas bubbles, including air, argon (Ar), helium (He), and Ar/He mixtures, were manipulated and ignited to the plasma state by dielectric barrier discharge (DBD) within a 50 μm-high gap between parallel plates. Moving and splitting the atmospheric-pressure microplasma in different gas bubbles were achieved by DEP. The excited light of the microplasma was recorded by an optical spectrometer for the optical emission spectroscopy (OES) analyses. The characteristic peaks of air, Ar, and He were observed in the DEP-driven microplasma. With the capability to manipulate bubbles and microplasma, this platform could be used for gas analyses in the future. PMID:22878730
10. STABILITY OF AQUEOUS FILMS BETWEEN BUBBLES
PubMed Central
Ohnishi, Satomi; Vogler, Erwin A.; Horn, Roger G.
2010-01-01
Film thinning experiments have been conducted with aqueous films between two air phases in a thin film pressure balance. The films are free of added surfactant but simple NaCl electrolyte is added in some experiments. Initially the experiments begin with a comparatively large volume of water in a cylindrical capillary tube a few mm in diameter, and by withdrawing water from the center of the tube the two bounding menisci are drawn together at a prescribed rate. This models two air bubbles approaching at a controlled speed. In pure water the results show three regimes of behavior depending on the approach speed: at slow speed (<1 µm/s) it is possible to form a flat film of pure water, ~100 nm thick, that is stabilised indefinitely by disjoining pressure due to repulsive double-layer interactions between naturally-charged air/water interfaces. The data are consistent with a surface potential of −57 mV on the bubble surfaces. At intermediate approach speed (~1 – 150 µm/s) the films are transiently stable due to hydrodynamic drainage effects, and bubble coalescence is delayed by ~10 – 100 s. At approach speeds greater than ~150 µm/s the hydrodynamic resistance appears to become negligible, and the bubbles coalesce without any measurable delay. Explanations for these observations are presented that take into account DLVO and Marangoni effects entering through disjoining pressure, surface mobility and hydrodynamic flow regimes in thin film drainage. In particular, it is argued that the dramatic reduction in hydrodynamic resistance is a transition from viscosity-controlled drainage to inertia-controlled drainage associated with a change from immobile to mobile air/water interfaces on increasing the speed of approach of two bubbles. A simple model is developed that accounts for the boundaries between different film stability or coalescence regimes. Predictions of the model are consistent with the data, and the effects of adding electrolyte can be explained. In
11. Electron bubbles in helium clusters. II. Probing superfluidity.
PubMed
Rosenblit, Michael; Jortner, Joshua
2006-05-21
In this paper we present calculations of electron tunneling times from the ground electronic state of excess electron bubbles in ((4)He)(N) clusters (N=6500-10(7), cluster radius R=41.5-478 A), where the equilibrium bubble radius varies in the range R(b)=13.5-17.0 A. For the bubble center located at a radial distance d from the cluster surface, the tunneling transition probability was expressed as A(0)phi(d,R)exp(-betad), where beta approximately 1 A(-1) is the exponential parameter, A(0) is the preexponential factor for the bubble located at the cluster center, and phi(d,R) is a correction factor which accounts for cluster curvature effects. Electron tunneling dynamics is grossly affected by the distinct mode of motion of the electron bubble in the image potential within the cluster, which is dissipative (i.e., tau(D)tau(0)) in superfluid ((4)He)(N) clusters, where tau(D) is the bubble motional damping time (tau(D) approximately 4 x 10(-12) s for normal fluid clusters and tau(D) approximately 10 s for superfluid clusters), while tau(0) approximately 10(-9)-10(-10) s is the bubble oscillatory time. Exceedingly long tunneling lifetimes, which cannot be experimentally observed, are manifested from bubbles damped to the center of the normal fluid cluster, while for superfluid clusters electron tunneling occurs from bubbles located in the vicinity of the initial distance d near the cluster boundary. Model calculations of the cluster size dependence of the electron tunneling time (for a fixed value of d=38-39 A), with lifetimes increasing in the range of 10(-3)-0.3 s for N=10(4)-10(7), account well for the experimental data [M. Farnik and J. P. Toennies, J. Chem. Phys. 118, 4176 (2003)], manifesting cluster curvature effects on electron tunneling dynamics. The minimal cluster size for the dynamic stability of the bubble was estimated to be N=3800, which represents the
12. Immobilization of a bubble in water by nanoelectrolysis
Hammadi, Zoubida; Lapena, Laurent; Morin, Roger; Olives, Juan
2016-08-01
A surprising phenomenon is presented: a bubble, produced from water electrolysis, is immobilized in the liquid (as if the Archimedes' buoyant force were annihilated). This is achieved using a nanoelectrode (1 nm to 1 μm of curvature radius at the apex) and an alternating electric potential with adapted values of amplitude and frequency. A simple model based on "nanoelectrolysis" (i.e., nanolocalization of the production of H2 and O2 molecules at the apex of the nanoelectrode) and an "open bubble" (i.e., exchanging H2 and O2 molecules with the solution) explains most of the observations.
13. Bubble Formation at a Submerged Orifice in Reduced Gravity
NASA Technical Reports Server (NTRS)
Buyevich, Yu A.; Webbon, Bruce W.
1994-01-01
The dynamic regime of gas injection through a circular plate orifice into an ideally wetting liquid is considered, when successively detached bubbles may be regarded as separate identities. In normal gravity and at relatively low gas flow rates, a growing bubble is modeled as a spherical segment touching the orifice perimeter during the whole time of its evolution. If the flow rate exceeds a certain threshold value, another stage of the detachment process takes place in which an almost spherical gas envelope is connected with the orifice by a nearly cylindrical stem that lengthens as the bubble rises above the plate. The bubble shape resembles then that of a mushroom and the upper envelope continues to grow until the gas supply through the stem is completely cut off. Such a stage is always present under conditions of sufficiently low gravity, irrespective of the flow rate. Two major reasons make for bubble detachment: the buoyancy force and the force due to the momentum inflow into the bubble with the injected gas. The former force dominates the process at normal gravity whereas the second one plays a key role under negligible gravity conditions. It is precisely this fundamental factor that conditions the drastic influence on bubble growth and detachment that changes in gravity are able to cause. The frequency of bubble formation is proportional to and the volume of detached bubbles is independent of the gas flow rate in sufficiently low gravity, while at normal and moderately reduced gravity conditions the first variable slightly decreases and the second one almost linearly increases as the flow rate grows. Effects of other parameters, such as the orifice radius, gas and liquid densities, and surface tension are discussed.
14. Approach to universality in axisymmetric bubble pinch-off
Gekle, Stephan; Snoeijer, Jacco H.; Lohse, Detlef; van der Meer, Devaraj
2009-09-01
The pinch-off of an axisymmetric air bubble surrounded by an inviscid fluid is compared in four physical realizations: (i) cavity collapse in the wake of an impacting disk, (ii) gas bubbles injected through a small orifice, (iii) bubble rupture in a straining flow, and (iv) a bubble with an initially necked shape. Our boundary-integral simulations suggest that all systems eventually follow the universal behavior characterized by slowly varying exponents predicted by J. Eggers [Phys. Rev. Lett. 98, 094502 (2007)]. However, the time scale for the onset of this final regime is found to vary by orders of magnitude depending on the system in question. While for the impacting disk it is well in the millisecond range, for the gas injection needle universal behavior sets in only a few microseconds before pinch-off. These findings reconcile the different views expressed in recent literature about the universal nature of bubble pinch-off.
15. Optimization of bubble column performance for nanoparticle collection.
PubMed
Cadavid-Rodriguez, M C; Charvet, A; Bemer, D; Thomas, D
2014-04-30
Fibrous media embody the most effective and widely used method of separating ultrafine particles from a carrier fluid. The main problem associated with them is filter clogging, which induces an increasingly marked pressure drop with time and thus imposes regular media cleaning or replacement. This context has prompted the idea of investigating bubble columns, which operate at constant pressure drop, as alternatives to fibrous filters. This study examines the influence of different operating conditions, such as liquid height, air flow rate, bubble size and presence of granular beds on ultrafine particle collection. Experimental results show that bubble columns are characterised by high collection efficiency, when they feature a large liquid height and small diameter bubbling orifices, while their efficiencies remain lower than those of fibrous filters. Gas velocity does not greatly influence collection efficiency, but the inclusion of a granular bed, composed of beads, increases the bubble residence time in the column, thereby increasing the column collection efficiency. PMID:24584069
16. Bubble and Drop Nonlinear Dynamics (BDND)
NASA Technical Reports Server (NTRS)
Trinh, E. H.; Leal, L. Gary; Thomas, D. A.; Crouch, R. K.
1998-01-01
Free drops and bubbles are weakly nonlinear mechanical systems that are relatively simple to characterize experimentally in 1-G as well as in microgravity. The understanding of the details of their motion contributes to the fundamental study of nonlinear phenomena and to the measurement of the thermophysical properties of freely levitated melts. The goal of this Glovebox-based experimental investigation is the low-gravity assessment of the capabilities of a modular apparatus based on ultrasonic resonators and on the pseudo- extinction optical method. The required experimental task is the accurate measurements of the large-amplitude dynamics of free drops and bubbles in the absence of large biasing influences such as gravity and levitation fields. A single-axis levitator used for the positioning of drops in air, and an ultrasonic water-filled resonator for the trapping of air bubbles have been evaluated in low-gravity and in 1-G. The basic feasibility of drop positioning and shape oscillations measurements has been verified by using a laptop-interfaced automated data acquisition and the optical extinction technique. The major purpose of the investigation was to identify the salient technical issues associated with the development of a full-scale Microgravity experiment on single drop and bubble dynamics.
17. Grout Long Radius Flow Testing to Support Saltstone Disposal Unit 6 Design - 13352
SciTech Connect
Stefanko, D.B.; Langton, C.A.; Serrato, M.G.; Brooks, T.E. II; Huff, T.H.
2013-07-01
designed to simulate slurry with the reference Saltstone rheology and a Saltstone with extra water from the process flushing operation. Long-radius flow tests were run using approximately 4.6 cubic meters of each of these mixes. In both tests the pump rate was 0.063 liters/second (1 gpm). A higher pump rate, 0.19 liters/second (3 gpm), was used in a third long-radius flow test. The angle of repose of the grout wedges increased as a function of time in all three tests. The final angles of repose were measured at 3.0 deg., 2.4 deg., and 0.72 deg.. The pump rate had the largest effect on the radial flow distance and slope of the grout surface. The slope on the pour placed at 0.19 liters/second (3 gpm) was most representative of the slope on the grout currently being pumped into SDU 2 which is estimated to be 0.7 deg. to 0.9 deg. The final grout heights at 1/3 of a meter from the discharge point were 115, 105, and 38 cm. Entrapped air (≥ 0.25 cm bubbles) was also observed in all of the mixes. The entrapped air appeared to be released from the flows within about 3.1 meters (10 feet) of the discharge point. The bleed water was clear but had a thin layer of floating particulates. The bleed water should be retrievable by a drain water collection system in SDU 6 assuming the system does not get clogged. Layering was observed and was attributed to intervals when the hopper was being cleaned. Heat from the hydration reactions was noticeable to the touch. (authors)
18. Grout long radius flow testing to support Saltstone disposal Unit 5 design
SciTech Connect
Stefanko, D. B.; Langton, C. A.; Serrato, M. G.; Brooks, T. E. II; Huff, T. H.
2013-02-24
) were designed to simulate slurry with the reference saltstone rheology and a saltstone with extra water from the process flushing operation. Long-radius flow tests were run using approximately 4.6 cubic meters of each of these mixes. In both tests the pump rate was 0.063 liters/second (1 gpm). A higher pump rate, 0.19 liters/second (3 gpm), was used in a third long-radius flow test. The angle of repose of the grout wedges increased as a function of time in all three tests. The final angles of repose were measured at 3.0º, 2.4º, and 0.72º. The pump rate had the largest effect on the radial flow distance and slope of the grout surface. The slope on the pour placed at 0.19 liters/second (3 gpm) was most representative of the slope on the grout currently being pumped into SDU 2 which is estimated to be 0.7º to 0.9º. The final grout heights at 1/3 of a meter from the discharge point were 115, 105, and 38 cm. Entrapped air (≥ 0.25 cm bubbles) was also observed in all of the mixes. The entrapped air appeared to be released from the flows within about 3.1 meters (10 feet) of the discharge point. The bleed water was clear but had a thin layer of floating particulates. The bleed water should be retrievable by a drain water collection system in SDU 6 assuming the system does not get clogged. Layering was observed and was attributed to intervals when the hopper was being cleaned. Heat from the hydration reactions was noticeable to the touch.
19. Bubble-induced acoustic mixing in a microfluidic device
Chen, Huaying; Petkovic-Duran, Karolina; Best, Michael; Zhu, Yonggang
2015-12-01
Homogeneous and fast mixing of samples at microscale is a critical requirement for successful applications of microfluidics in biochemical analysis, chemical synthesis, drug delivery and nanomaterial synthesis. This paper reports the optimisation of bubble-induced mixing in a microfluidic device in terms of voltage, driving frequency, piezo transducer position and PDMS thickness. The microfluidic device consists of a microwell (with the diameter of 1mm and volume of ~95 nL) with two rectangular bubble traps (400×400μm) on both sides of the well. After the injection of liquid, air bubbles were spontaneously trapped in two rectangular traps. When the frequency of a piezo was equal to the resonance frequency of air bubbles, strong liquid recirculation formed (so called acoustic microstreaming) in the vicinity of the interface of air bubbles and water. The acoustic induced flow of microbeads and mixing of water and fluorescence dye were imaged to study the mixing efficiency. For a given voltage and PDMS thickness, when the piezo was placed on top of the well, the mixing was most vigorous. For a given frequency, the mixing efficiency was directly proportional to the voltage (4-20V) and inversely proportional to the PDMS thickness (0.3-2mm). When the frequency driving the piezo was approaching the resonance frequency of air bubbles, the mixing efficiency was maximal, while when it was far away from the resonance frequency of air bubbles, the mixing efficiency was much lower. This work provides guidance to the design and the application of bubble-induced acoustic mixing in microfluidics.
20. Bubble reconstruction method for wire-mesh sensors measurements
Mukin, Roman V.
2016-08-01
A new algorithm is presented for post-processing of void fraction measurements with wire-mesh sensors, particularly for identifying and reconstructing bubble surfaces in a two-phase flow. This method is a combination of the bubble recognition algorithm presented in Prasser (Nuclear Eng Des 237(15):1608, 2007) and Poisson surface reconstruction algorithm developed in Kazhdan et al. (Poisson surface reconstruction. In: Proceedings of the fourth eurographics symposium on geometry processing 7, 2006). To verify the proposed technique, a comparison was done of the reconstructed individual bubble shapes with those obtained numerically in Sato and Ničeno (Int J Numer Methods Fluids 70(4):441, 2012). Using the difference between reconstructed and referenced bubble shapes, the accuracy of the proposed algorithm was estimated. At the next step, the algorithm was applied to void fraction measurements performed in Ylönen (High-resolution flow structure measurements in a rod bundle (Diss., Eidgenössische Technische Hochschule ETH Zürich, Nr. 20961, 2013) by means of wire-mesh sensors in a rod bundle geometry. The reconstructed bubble shape yields bubble surface area and volume, hence its Sauter diameter d_{32} as well. Sauter diameter is proved to be more suitable for bubbles size characterization compared to volumetric diameter d_{30}, proved capable to capture the bi-disperse bubble size distribution in the flow. The effect of a spacer grid was studied as well: For the given spacer grid and considered flow rates, bubble size frequency distribution is obtained almost at the same position for all cases, approximately at d_{32} = 3.5 mm. This finding can be related to the specific geometry of the spacer grid or the air injection device applied in the experiments, or even to more fundamental properties of the bubble breakup and coagulation processes. In addition, an application of the new algorithm for reconstruction of a large air-water interface in a tube bundle is
1. Herds of methane chambers grazing bubbles
Grinham, Alistair; Dunbabin, Matthew
2014-05-01
Water to air methane emissions from freshwater reservoirs can be dominated by sediment bubbling (ebullitive) events. Previous work to quantify methane bubbling from a number of Australian sub-tropical reservoirs has shown that this can contribute as much as 95% of total emissions. These bubbling events are controlled by a variety of different factors including water depth, surface and internal waves, wind seiching, atmospheric pressure changes and water levels changes. Key to quantifying the magnitude of this emission pathway is estimating both the bubbling rate as well as the areal extent of bubbling. Both bubbling rate and areal extent are seldom constant and require persistent monitoring over extended time periods before true estimates can be generated. In this paper we present a novel system for persistent monitoring of both bubbling rate and areal extent using multiple robotic surface chambers and adaptive sampling (grazing) algorithms to automate the quantification process. Individual chambers are self-propelled and guided and communicate between each other without the need for supervised control. They can maintain station at a sampling site for a desired incubation period and continuously monitor, record and report fluxes during the incubation. To exploit the methane sensor detection capabilities, the chamber can be automatically lowered to decrease the head-space and increase concentration. The grazing algorithms assign a hierarchical order to chambers within a preselected zone. Chambers then converge on the individual recording the highest 15 minute bubbling rate. Individuals maintain a specified distance apart from each other during each sampling period before all individuals are then required to move to different locations based on a sampling algorithm (systematic or adaptive) exploiting prior measurements. This system has been field tested on a large-scale subtropical reservoir, Little Nerang Dam, and over monthly timescales. Using this technique
2. Effective Compressibility of a Bubbly Slurry.
PubMed
Kam, S. I.; Gauglitz, P. A.; Rossen, W. R.
2001-09-01
The goal of this study is to fit model parameters to changes in waste level in response to barometric pressure changes in underground storage tanks at the Hanford Site. This waste compressibility is a measure of the quantity of gas, typically hydrogen and other flammable gases, that can pose a safety hazard, retained in the waste. A one-dimensional biconical-pore-network model for compressibility of a bubbly slurry is presented in a companion paper. Fitting these results to actual waste level changes in the tanks implies that bubbles in the slurry layer are long and the ratio of pore-body radius to pore-throat radius is close to 1; unfortunately, compressibility can not be quantified unambiguously from the data without additional information on pore geometry. Therefore, determining the quantity of gas in the tanks requires more than just waste-level data. The non-uniqueness of the fit is also found with two other simple models: a capillary-tube model with contact angle hysteresis and a spherical-pore model. Copyright 2001 Academic Press. PMID:11502128
3. Treatment of distal radius fractures.
PubMed
Murray, Jayson; Gross, Leeaht
2013-08-01
The American Academy of Orthopaedic Surgeons has developed Appropriate Use Criteria (AUC) for treating distal radius fractures (DRF). Evidence-based information, in conjunction with the clinical expertise of physicians, was used to develop the criteria to improve patient care and obtain best outcomes while considering the subtleties and distinctions necessary in making clinical decisions. The DRF AUC clinical patient scenarios were derived from patient indications that generally accompany a DRF, as well as from current evidence-based clinical practice guidelines and supporting literature. The 216 indications and 10 treatments were developed by the Writing Panel, a group of clinicians who are specialists in this AUC topic. Next, the Review Panel, a separate group of volunteer physicians, independently reviewed these materials to ensure that they were representative of patient scenarios that clinicians are likely to encounter in daily practice. Finally, the multidisciplinary Voting Panel (made up of specialists and nonspecialists) rated the appropriateness of treatment of each patient scenario using a 9-point scale to designate a treatment as Appropriate (median rating, 7 to 9), May Be Appropriate (median rating, 4 to 6), or Rarely Appropriate (median rating, 1 to 3). PMID:23908256
4. Colliding with a crunching bubble
SciTech Connect
Freivogel, Ben; Freivogel, Ben; Horowitz, Gary T.; Shenker, Stephen
2007-03-26
In the context of eternal inflation we discuss the fate of Lambda = 0 bubbles when they collide with Lambda< 0 crunching bubbles. When the Lambda = 0 bubble is supersymmetric, it is not completely destroyed by collisions. If the domain wall separating the bubbles has higher tension than the BPS bound, it is expelled from the Lambda = 0 bubble and does not alter its long time behavior. If the domain wall saturates the BPS bound, then it stays inside the Lambda = 0 bubble and removes a finite fraction of future infinity. In this case, the crunch singularity is hidden behind the horizon of a stable hyperbolic black hole.
5. Turbulent bubbly flow
van den Berg, Thomas H.; Luther, Stefan; Mazzitelli, Irene M.; Rensen, Judith M.; Toschi, Federico; Lohse, Detlef
The effect of bubbles on fully developed turbulent flow is investigated numerically and experimentally, summarizing the results of our previous papers (Mazzitelli et al., 2003, Physics of Fluids15, L5. and Journal of Fluid Mechanics488, 283; Rensen, J. et al. 2005, Journal of Fluid Mechanics538, 153). On the numerical side, we simulate Navier Stokes turbulence with a Taylor Reynolds number of Re?˜60, a large large-scale forcing, and periodic boundary conditions. The point-like bubbles follow their Lagrangian paths and act as point forces on the flow. As a consequence, the spectral slope is less steep as compared to the Kolmogorov case. The slope decrease is identified as a lift force effect. On the experimental side, we do hot-film anemometry in a turbulent water channel with Re? ˜ 200 in which we have injected small bubbles up to a volume percentage of 3%. Here the challenge is to disentangle the bubble spikes from the hot-film velocity signal. To achieve this goal, we have developed a pattern recognition scheme. Furthermore, we injected microbubbles up to a volume percentage of 0.3%. Both in the counter flowing situation with small bubbles and in the co-flow situation with microbubbles, we obtain a less spectral slope, in agreement with the numerical result.
6. Bubbles of Metamorphosis
Prakash, Manu
2011-11-01
Metamorphosis presents a puzzling challenge where, triggered by a signal, an organism abruptly transforms its entire shape and form. Here I describe the role of physical fluid dynamic processes during pupal metamorphosis in flies. During early stages of pupation of third instar larvae into adult flies, a physical gas bubble nucleates at a precise temporal and spatial location, as part of the normal developmental program in Diptera. Although its existence has been known for the last 100 years, the origin and control of this cavitation'' event has remained completely mysterious. Where does the driving negative pressure for bubble nucleation come from? How is the location of the bubble nucleation site encoded in the pupae? How do molecular processes control such a physical event? What is the role of this bubble during development? Via developing in-vivo imaging techniques, direct bio-physical measurements in live insect pupal structures and physical modeling, here I elucidate the physical mechanism for appearance and disappearance of this bubble and predict the site of nucleation and its exact timing. This new physical insight into the process of metamorphosis also allows us to understand the inherent design of pupal shell architectures in various species of insects. Milton Award, Harvard Society of Fellows; Terman Fellowship, Stanford
7. Plasma in sonoluminescing bubble.
PubMed
An, Yu
2006-12-22
With the new accommodation coefficient of water vapor evaluated by molecular dynamics model, the maximum temperature of a sonoluminescing bubble calculated with the full partial differential equations easily reaches few tens of thousands degrees. Though at this temperature the gas is weakly ionized (10% or less), the gas density inside a sonoluminescing bubble at the moment of the bubble's flashing is so high that there still forms a dense plasma. The light emission of the bubble is calculated by the plasma model which is compared with that by the bremsstrahlung (electron-ion, electron-neutral atom) and recombination model. The calculation by the two models shows that for the relatively low maximum temperature (< 30,000 K) of the bubble, the pulse width is independent of the wavelength and the spectrum deviates the black body radiation type; while for the relatively high maximum temperature (approximately 60,000 K), the pulse width is dependent of the wavelength and the spectrum is an almost perfect black body radiation spectrum. The maximum temperature calculated by the gas dynamics equations is much higher than the temperature fitted by the black body radiation formula. PMID:16797657
8. A Bubble Bursts
NASA Technical Reports Server (NTRS)
2005-01-01
RCW 79 is seen in the southern Milky Way, 17,200 light-years from Earth in the constellation Centaurus. The bubble is 70-light years in diameter, and probably took about one million years to form from the radiation and winds of hot young stars.
The balloon of gas and dust is an example of stimulated star formation. Such stars are born when the hot bubble expands into the interstellar gas and dust around it. RCW 79 has spawned at least two groups of new stars along the edge of the large bubble. Some are visible inside the small bubble in the lower left corner. Another group of baby stars appears near the opening at the top.
NASA's Spitzer Space Telescope easily detects infrared light from the dust particles in RCW 79. The young stars within RCW 79 radiate ultraviolet light that excites molecules of dust within the bubble. This causes the dust grains to emit infrared light that is detected by Spitzer and seen here as the extended red features.
9. BLOWING COSMIC BUBBLES
NASA Technical Reports Server (NTRS)
2002-01-01
This NASA Hubble Space Telescope image reveals an expanding shell of glowing gas surrounding a hot, massive star in our Milky Way Galaxy. This shell is being shaped by strong stellar winds of material and radiation produced by the bright star at the left, which is 10 to 20 times more massive than our Sun. These fierce winds are sculpting the surrounding material - composed of gas and dust - into the curve-shaped bubble. Astronomers have dubbed it the Bubble Nebula (NGC 7635). The nebula is 10 light-years across, more than twice the distance from Earth to the nearest star. Only part of the bubble is visible in this image. The glowing gas in the lower right-hand corner is a dense region of material that is getting blasted by radiation from the Bubble Nebula's massive star. The radiation is eating into the gas, creating finger-like features. This interaction also heats up the gas, causing it to glow. Scientists study the Bubble Nebula to understand how hot stars interact with the surrounding material. Credit: Hubble Heritage Team (AURA/STScI/NASA)
10. Sliding bubble dynamics and the effects on surface heat transfer
Donnelly, B.; Robinson, A. J.; Delauré, Y. M. C.; Murray, D. B.
2012-11-01
An investigation into the effects of a single sliding air bubble on heat transfer from a submerged, inclined surface has been undertaken. Existing literature has shown that both vapour and gas bubbles can increase heat transfer rates from adjacent heated surfaces. However, the mechanisms involved are complex and dynamic and in some cases poorly understood. The present study utilises high speed, high resolution, infrared thermography and video photography to measure two dimensional surface heat transfer and three dimensional bubble position and shape. This provides a unique insight into the complex interactions at the heated surface. Bubbles of volume 0.05, 0.1, 0.2 and 0.4 ml were released onto a surface inclined at 30 degrees to horizontal. Results confirmed that sliding bubbles can enhance heat transfer rates up to a factor of 9 and further insight was gained about the mechanisms behind this phenomenon. The enhancement effects were observed over large areas and persisted for a long duration with the bubble exhibiting complex shape and path oscillations. It is believed that the periodic wake structure present behind the sliding bubble affects the bubble motion and is responsible for the heat transfer effects observed. The nature of this wake is proposed to be that of a chain of horseshoe vortices.
11. Black Hole Blows Big Bubble
2010-07-01
astronomers understand the similarity between small black holes formed from exploded stars and the supermassive black holes at the centres of galaxies. Very powerful jets have been seen from supermassive black holes, but are thought to be less frequent in the smaller microquasar variety. The new discovery suggests that many of them may simply have gone unnoticed so far. The gas-blowing black hole is located 12 million light-years away, in the outskirts of the spiral galaxy NGC 7793 (eso0914b). From the size and expansion velocity of the bubble the astronomers have found that the jet activity must have been ongoing for at least 200 000 years. Note: [1] Astronomers do not have yet any means of measuring the size of the black hole itself. The smallest stellar black hole discovered so far has a radius of about 15 km. An average stellar black hole of about 10 solar masses has a radius of about 30 km, while a "big" stellar black hole may have a radius of up to 300 km. This is still much smaller than the jets, which extend out to 1000 light-years, or about 9000 million million km! More Information: This result appears in a paper published in this week's issue of the journal Nature (A 300 parsec long jet-inflated bubble around a powerful microquasar in the galaxy NGC 7793, by Manfred W. Pakull, Roberto Soria and Christian Motch). ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates
12. Black Hole Blows Big Bubble
2010-07-01
astronomers understand the similarity between small black holes formed from exploded stars and the supermassive black holes at the centres of galaxies. Very powerful jets have been seen from supermassive black holes, but are thought to be less frequent in the smaller microquasar variety. The new discovery suggests that many of them may simply have gone unnoticed so far. The gas-blowing black hole is located 12 million light-years away, in the outskirts of the spiral galaxy NGC 7793 (eso0914b). From the size and expansion velocity of the bubble the astronomers have found that the jet activity must have been ongoing for at least 200 000 years. Notes [1] Astronomers do not have yet any means of measuring the size of the black hole itself. The smallest stellar black hole discovered so far has a radius of about 15 km. An average stellar black hole of about 10 solar masses has a radius of about 30 km, while a "big" stellar black hole may have a radius of up to 300 km. This is still much smaller than the jets, which extend out to several hundreds light years on each side of the black hole, or about several thousand million million km! More information This result appears in a paper published in this week's issue of the journal Nature (A 300 parsec long jet-inflated bubble around a powerful microquasar in the galaxy NGC 7793, by Manfred W. Pakull, Roberto Soria and Christian Motch). ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising
13. Black Hole Blows Big Bubble
2010-07-01
astronomers understand the similarity between small black holes formed from exploded stars and the supermassive black holes at the centres of galaxies. Very powerful jets have been seen from supermassive black holes, but are thought to be less frequent in the smaller microquasar variety. The new discovery suggests that many of them may simply have gone unnoticed so far. The gas-blowing black hole is located 12 million light-years away, in the outskirts of the spiral galaxy NGC 7793 (eso0914b). From the size and expansion velocity of the bubble the astronomers have found that the jet activity must have been ongoing for at least 200 000 years. Note: [1] Astronomers do not have yet any means of measuring the size of the black hole itself. The smallest stellar black hole discovered so far has a radius of about 15 km. An average stellar black hole of about 10 solar masses has a radius of about 30 km, while a "big" stellar black hole may have a radius of up to 300 km. This is still much smaller than the jets, which extend out to 1000 light-years, or about 9000 million million km! More Information: This result appears in a paper published in this week's issue of the journal Nature (A 300 parsec long jet-inflated bubble around a powerful microquasar in the galaxy NGC 7793, by Manfred W. Pakull, Roberto Soria and Christian Motch). ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates
14. Black Hole Blows Big Bubble
2010-07-01
astronomers understand the similarity between small black holes formed from exploded stars and the supermassive black holes at the centres of galaxies. Very powerful jets have been seen from supermassive black holes, but are thought to be less frequent in the smaller microquasar variety. The new discovery suggests that many of them may simply have gone unnoticed so far. The gas-blowing black hole is located 12 million light-years away, in the outskirts of the spiral galaxy NGC 7793 (eso0914b). From the size and expansion velocity of the bubble the astronomers have found that the jet activity must have been ongoing for at least 200 000 years. Notes [1] Astronomers do not have yet any means of measuring the size of the black hole itself. The smallest stellar black hole discovered so far has a radius of about 15 km. An average stellar black hole of about 10 solar masses has a radius of about 30 km, while a "big" stellar black hole may have a radius of up to 300 km. This is still much smaller than the jets, which extend out to several hundreds light years on each side of the black hole, or about several thousand million million km! More information This result appears in a paper published in this week's issue of the journal Nature (A 300 parsec long jet-inflated bubble around a powerful microquasar in the galaxy NGC 7793, by Manfred W. Pakull, Roberto Soria and Christian Motch). ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising
15. Experimental and numerical study on the dynamic pressure caused by the bubble jet
Li, S.; Zhang, A. M.; Yao, X. L.
2015-12-01
The high speed liquid jet is an important mechanism of damage to hydraulic machinery by cavitation bubbles, as well as damage to vessels by underwater explosion bubble. In this study, the bubble motion near a wall and the pressure impulse are investigated through experimental and numerical methods. In the experiment, the bubble is generated by the electric discharge, and a high speed camera is used to capture the bubble motion. Numerical studies are conducted using the boundary element method, and the vortex ring model is adopted to deal with the discontinued potential of the toroidal bubble. Calculated results show excellent agreement with experimental observations. Meanwhile, the dynamic pressure caused by the bubble in the flow domain is calculated by an auxiliary function, which improves the accuracy of the results. A highly localized pressure region will be generated on the wall by the bubble jet. The optimal stand-off parameter (the ratio of the distance the bubble center at inception from the wall to the maximum bubble radius) for a most damaging jet formation is around 0.9.
16. Venous gas embolism - Time course of residual pulmonary intravascular bubbles
NASA Technical Reports Server (NTRS)
Butler, B. D.; Luehr, S.; Katz, J.
1989-01-01
A study was carried out to determine the time course of residual pulmonary intravascular bubbles after embolization with known amounts of venous air, using an N2O challenge technique. Attention was also given to the length of time that the venous gas emboli remained as discrete bubbles in the lungs with 100 percent oxygen ventilation. The data indicate that venous gas emboli can remain in the pulmonary vasculature as discrete bubbles for periods lasting up to 43 + or - 10.8 min in dogs ventilated with oxygen and nitrogen. With 100 percent oxygen ventilation, these values are reduced significantly to 19 + or - 2.5 min.
17. Study of bubble behavior in weightlessness (effects of thermal gradient and acoustic stationary wave) (M-16)
NASA Technical Reports Server (NTRS)
Azuma, H.
1993-01-01
loop according to whether its diameter is larger or smaller than that of the main resonant radius. In our experiment fine bubbles will be observed to move according to an acoustic field formed in a cylindrical cell. The existence of bubbles varies the acoustic speed, and the interactive force between bubbles will make the bubble behavior collective and complicated. This experiment will be very useful to development of bubble removable technology as well as to the understanding of bubble behavior.
18. Dynamical model of bubble path instability.
PubMed
Shew, Woodrow L; Pinton, Jean-François
2006-10-01
Millimeter-sized air bubbles rising through still water are known to exhibit zigzag and spiral oscillatory trajectories. We present a system of four ordinary differential equations which effectively model these dynamics. The model is based on Kirchhoff's equations and several physical arguments derived from our experimental observations. In the framework of this model, the zigzag and the spiral motions result from the same underlying bifurcation to wake instability. PMID:17155262
19. Effect of direct bubble-bubble interactions on linear-wave propagation in bubbly liquids
Fuster, D.; Conoir, J. M.; Colonius, T.
2014-12-01
We study the influence of bubble-bubble interactions on the propagation of linear acoustic waves in bubbly liquids. Using the full model proposed by Fuster and Colonius [J. Fluid Mech. 688, 253 (2011), 10.1017/jfm.2011.380], numerical simulations reveal that direct bubble-bubble interactions have an appreciable effect for frequencies above the natural resonance frequency of the average size bubble. Based on the new results, a modification of the classical wave propagation theory is proposed. The results obtained are in good agreement with previously reported experimental data where the classical linear theory systematically overpredicts the effective attenuation and phase velocity.
20. Bubbles from nothing
SciTech Connect
2012-01-01
Within the framework of flux compactifications, we construct an instanton describing the quantum creation of an open universe from nothing. The solution has many features in common with the smooth 6d bubble of nothing solutions discussed recently, where the spacetime is described by a 4d compactification of a 6d Einstein-Maxwell theory on S{sup 2} stabilized by flux. The four-dimensional description of this instanton reduces to that of Hawking and Turok. The choice of parameters uniquely determines all future evolution, which we additionally find to be stable against bubble of nothing instabilities.
1. Heated Gas Bubbles
NASA Technical Reports Server (NTRS)
2004-01-01
Fluid Physics is study of the motion of fluids and the effects of such motion. When a liquid is heated from the bottom to the boiling point in Earth's microgravity, small bubbles of heated gas form near the bottom of the container and are carried to the top of the liquid by gravity-driven convective flows. In the same setup in microgravity, the lack of convection and buoyancy allows the heated gas bubbles to grow larger and remain attached to the container's bottom for a significantly longer period.
2. Mechanics of collapsing cavitation bubbles.
PubMed
van Wijngaarden, Leen
2016-03-01
A brief survey is given of the dynamical phenomena accompanying the collapse of cavitation bubbles. The discussion includes shock waves, microjets and the various ways in which collapsing bubbles produce damage. PMID:25890856
3. Mirror with thermally controlled radius of curvature
DOEpatents
Neil, George R.; Shinn, Michelle D.
2010-06-22
A radius of curvature controlled mirror for controlling precisely the focal point of a laser beam or other light beam. The radius of curvature controlled mirror provides nearly spherical distortion of the mirror in response to differential expansion between the front and rear surfaces of the mirror. The radius of curvature controlled mirror compensates for changes in other optical components due to heating or other physical changes. The radius of curvature controlled mirror includes an arrangement for adjusting the temperature of the front surface and separately adjusting the temperature of the rear surface to control the radius of curvature. The temperature adjustment arrangements can include cooling channels within the mirror body or convection of a gas upon the surface of the mirror. A control system controls the differential expansion between the front and rear surfaces to achieve the desired radius of curvature.
4. Fluid Dynamics of Bubbly Liquids
NASA Technical Reports Server (NTRS)
Tsang, Y. H.; Koch, D. L.; Zenit, R.; Sangani, A.; Kushch, V. I.; Spelt, P. D. M.; Hoffman, M.; Nahra, H.; Fritz, C.; Dolesh, R.
2002-01-01
Experiments have been performed to study the average flow properties of inertially dominated bubbly liquids which may be described by a novel analysis. Bubbles with high Reynolds number and low Weber number may produce a fluid velocity disturbance that can be approximated by a potential flow. We studied the behavior of suspensions of bubbles of about 1.5 mm diameter in vertical and inclined channels. The suspension was produced using a bank of 900 glass capillaries with inner diameter of about 100 microns in a quasi-steady fashion. In addition, salt was added to the suspension to prevent bubble-bubble coalescence. As a result, a nearly monodisperse suspension of bubble was produced. By increasing the inclination angle, we were able to explore an increasing amount of shear to buoyancy motion. A pipe flow experiment with the liquid being recirculated is under construction. This will provide an even larger range of shear to buoyancy motion. We are planning a microgravity experiment in which a bubble suspension is subjected to shearing in a couette cell in the absence of a buoyancy-driven relative motion of the two phases. By employing a single-wire, hot film anemometer, we were able to obtain the liquid velocity fluctuations. The shear stress at the wall was measured using a hot film probe flush mounted on the wall. The gas volume fraction, bubble velocity, and bubble velocity fluctuations were measured using a homemade, dual impedance probe. In addition, we also employed a high-speed camera to obtain the bubble size distribution and bubble shape in a dilute suspension. A rapid decrease in bubble velocity for a dilute bubble suspension is attributed to the effects of bubble-wall collisions. The more gradual decrease of bubble velocity as gas volume fraction increases, due to subsequent hindering of bubble motion, is in qualitative agreement with the predictions of Spelt and Sangani for the effects of potential-flow bubble-bubble interactions on the mean velocity. The
5. Modeling and Measurements of Multiphase Flow and Bubble Entrapment in Steel Continuous Casting
Jin, Kai; Thomas, Brian G.; Ruan, Xiaoming
2016-02-01
In steel continuous casting, argon gas is usually injected to prevent clogging, but the bubbles also affect the flow pattern, and may become entrapped to form defects in the final product. To investigate this behavior, plant measurements were conducted, and a computational model was applied to simulate turbulent flow of the molten steel and the transport and capture of argon gas bubbles into the solidifying shell in a continuous slab caster. First, the flow field was solved with an Eulerian k- ɛ model of the steel, which was two-way coupled with a Lagrangian model of the large bubbles using a discrete random walk method to simulate their turbulent dispersion. The flow predicted on the top surface agreed well with nailboard measurements and indicated strong cross flow caused by biased flow of Ar gas due to the slide-gate orientation. Then, the trajectories and capture of over two million bubbles (25 μm to 5 mm diameter range) were simulated using two different capture criteria (simple and advanced). Results with the advanced capture criterion agreed well with measurements of the number, locations, and sizes of captured bubbles, especially for larger bubbles. The relative capture fraction of 0.3 pct was close to the measured 0.4 pct for 1 mm bubbles and occurred mainly near the top surface. About 85 pct of smaller bubbles were captured, mostly deeper down in the caster. Due to the biased flow, more bubbles were captured on the inner radius, especially near the nozzle. On the outer radius, more bubbles were captured near to narrow face. The model presented here is an efficient tool to study the capture of bubbles and inclusion particles in solidification processes.
6. Conformal grasping using feedback controlled bubble actuator array
Carrigan, Wei; Stein, Richard; Mittal, Manoj; Wijesundara, Muthu B. J.
2014-06-01
This paper presents an implementation of a bubble actuator array (BAA) based active robotic skin, a modular system, onto existing low cost robotic end-effectors or prosthetic hands for conformal grasping of objects. The active skin is comprised of pneumatically controlled polyurethane rubber bubbles with overlaid sensors for feedback control. Sensor feedback allows the BAA based robotic skin to conformally grasp an object with an explicit uniform force distribution. The bubble actuator array reported here is capable of applying up to 4N of force at each point of contact and tested for conformally grasping objects with a radius of curvature up to 57.15mm. Once integrated onto a two-finger gripper with one degree of freedom (DOF), the active skin was shown to reduce point of contact forces of up to 50% for grasped objects.
7. Bubble coalescence in a power-law fluid
Kamat, Pritish; Thete, Sumeet; Basaran, Osman
2015-11-01
As two spherical gas bubbles in a liquid are slowly brought together, the liquid film or sheet between them drains and ultimately ruptures, forming a circular hole that connects them. The high curvature near the edge of the liquid sheet drives flow radially outward, causing the film to retract and the radius of the hole to increase with time. Recent experimental and theoretical work in this area has uncovered self-similarity and universal scaling regimes when two bubbles coalesce in a Newtonian fluid. Motivated by applications such as polymer and composites processing, food and drug manufacture, and aeration/deaeration systems where the liquids often exhibit deformation-rate thinning rheology, we extend the recent Newtonian studies to bubble coalescence in power-law fluids. In our work, we use a combination of thin-film theory and full 3D, axisymmetric computations to probe the dynamics in the aftermath of the singularity.
8. Collapsing Bubble in Metal for High Energy Density Physics Study
SciTech Connect
Ng, S F; Barnard, J J; Leung, P T; Yu, S S
2011-04-13
This paper presents a new idea to produce matter in the high energy density physics (HEDP) regime in the laboratory using an intense ion beam. A gas bubble created inside a solid metal may collapse by driving it with an intense ion beam. The melted metal will compress the gas bubble and supply extra energy to it. Simulations show that the spherical implosion ratio can be about 5 and at the stagnation point, the maximum density, temperature and pressure inside the gas bubble can go up to nearly 2 times solid density, 10 eV and a few megabar (Mbar) respectively. The proposed experiment is the first to permit access into the Mbar regime with existing or near-term ion facilities, and opens up possibilities for new physics gained through careful comparisons of simulations with measurements of quantities like stagnation radius, peak temperature and peak pressure at the metal wall.
9. Ground State Properties and Bubble Structure of Synthesized Superheavy Nuclei
Singh, S. K.; Ikram, M.; Patra, S. K.
2013-01-01
We calculate the ground state properties of recently synthesized superheavy elements (SHEs) from Z = 105-118 along with the predicted proton magic Z = 120. The relativistic and nonrelativistic mean field formalisms are used to evaluate the binding energy (BE), charge radius, quadrupole deformation parameter and the density distribution of nucleons. We analyzed the stability of the nuclei based on BE and neutron to proton ratio. We also studied the bubble structure which reveals the special features of the superheavy nuclei.
10. DNS studies of bubbly flows
Tryggvason, Gretar; Esmaeeli, Asghar; Biswas, Souvik
2004-11-01
Recent stuies of bubbly flows, using direct numerical simulations, are discussed. The goal of this study is to examine the collective behavior of many bubbles as the rise Reynolds number is increased and and a single bubble rises unsteadily, as well as to examine the motion of bubbles in channels. A front-tracking/finite volume method is used to fully resolve all flow scales, including the bubbles and the flow around them. Two cases are simulated, for one the bubbles remain nearly spherical and for the other case the bubbles are deformable and wobble. The wobbly bubbles remains relatively uniformly distributed and are not susceptible to the streaming instability found by Bunner and Tryggvason (2003) for deformable bubbles at lower rise Reynolds numbers. The more spherical bubbles, on the other hand, form transients rafts'' somewhat similar to those seen in potential flow simulation of many bubbles. For channel flow we compare results from direct numerical simulations of bubbly flow with prediction of the steady-state two-fluid model of Antal, Lahey, and Flaherty (1991). The simulations are done assuming a two-dimensional system and the model coefficients are adjusted slightly to match the data for upflow. The results generally agree reasonably well, even though the simulated void fraction is considerably higher than the one assumed in the derivation of the model. Research supported by DOE.
11. Cohesion of Bubbles in Foam
ERIC Educational Resources Information Center
Ross, Sydney
1978-01-01
The free-energy change, or binding energy, of an idealized bubble cluster is calculated on the basis of one mole of gas, and on the basis of a single bubble going from sphere to polyhedron. Some new relations of bubble geometry are developed in the course of the calculation. (BB)
12. Bubble Eliminator Based on Centrifugal Flow
NASA Technical Reports Server (NTRS)
Gonda, Steve R.; Tsao, Yow-Min D.; Lee, Wenshan
2004-01-01
The fluid bubble eliminator (FBE) is a device that removes gas bubbles from a flowing liquid. The FBE contains no moving parts and does not require any power input beyond that needed to pump the liquid. In the FBE, the buoyant force for separating the gas from the liquid is provided by a radial pressure gradient associated with a centrifugal flow of the liquid and any entrained bubbles. A device based on a similar principle is described in Centrifugal Adsorption Cartridge System (MSC- 22863), which appears on page 48 of this issue. The FBE was originally intended for use in filtering bubbles out of a liquid flowing relatively slowly in a bioreactor system in microgravity. Versions that operate in normal Earth gravitation at greater flow speeds may also be feasible. The FBE (see figure) is constructed as a cartridge that includes two concentric cylinders with flanges at the ends. The outer cylinder is an impermeable housing; the inner cylinder comprises a gas-permeable, liquid-impermeable membrane covering a perforated inner tube. Multiple spiral disks that collectively constitute a spiral ramp are mounted in the space between the inner and outer cylinders. The liquid enters the FBE through an end flange, flows in the annular space between the cylinders, and leaves through the opposite end flange. The spiral disks channel the liquid into a spiral flow, the circumferential component of which gives rise to the desired centrifugal effect. The resulting radial pressure gradient forces the bubbles radially inward; that is, toward the inner cylinder. At the inner cylinder, the gas-permeable, liquid-impermeable membrane allows the bubbles to enter the perforated inner tube while keeping the liquid in the space between the inner and outer cylinders. The gas thus collected can be vented via an endflange connection to the inner tube. The centripetal acceleration (and thus the radial pressure gradient) is approximately proportional to the square of the flow speed and
13. A Study of Bubble and Slug Gas-Liquid Flow in a Microgravity Environment
NASA Technical Reports Server (NTRS)
McQuillen, J.
2000-01-01
surfactant), to identify clusters that promote coalescence and transition the void fraction distribution in bubbly and slug flow,to measure the wall friction in bubbly flow. These experiments will consist of multiple bubbles type flows and will utilize hot wire and film anemometers to measure liquid velocity and wall shear stress respectively and double fiber optic probes to measure bubble size and velocity as a function of tube radius and axial location.
14. Characterization of acoustic droplet vaporization for control of bubble generation under flow conditions.
PubMed
Kang, Shih-Tsung; Huang, Yi-Luan; Yeh, Chih-Kuang
2014-03-01
This study investigated the manipulation of bubbles generated by acoustic droplet vaporization (ADV) under clinically relevant flow conditions. Optical microscopy and high-frequency ultrasound imaging were used to observe bubbles generated by 2-MHz ultrasound pulses at different time points after the onset of ADV. The dependence of the bubble population on droplet concentration, flow velocity, fluid viscosity and acoustic parameters, including acoustic pressure, pulse duration and pulse repetition frequency, was investigated. The results indicated that post-ADV bubble growth spontaneously driven by air permeation markedly affected the bubble population after insonation. The bubbles can grow to a stable equilibrium diameter as great as twice the original diameter in 0.5-1 s, as predicted by the theoretical calculation. The growth trend is independent of flow velocity, but dependent on fluid viscosity and droplet concentration, which directly influence the rate of gas uptake by bubbles and the rate of gas exchange across the wall of the semipermeable tube containing the bubbles and, hence, the gas content of the host medium. Varying the acoustic pressure does not markedly change the formation of bubbles as long as the ADV thresholds of most droplets are reached. Varying pulse duration and pulse repetition frequency markedly reduces the number of bubbles. Lengthening pulse duration favors the production of large bubbles, but reduces the total number of bubbles. Increasing the PRF interestingly provides superior performance in bubble disruption. These results also suggest that an ADV bubble population cannot be assessed simply on the basis of initial droplet size or enhancement of imaging contrast by the bubbles. Determining the optimal acoustic parameters requires careful consideration of their impact on the bubble population produced for different application scenarios. PMID:24433748
15. Size distributions of micro-bubbles generated by a pressurized dissolution method
Taya, C.; Maeda, Y.; Hosokawa, S.; Tomiyama, A.; Ito, Y.
2012-03-01
Size of micro-bubbles is widely distributed in the range of one to several hundreds micrometers and depends on generation methods, flow conditions and elapsed times after the bubble generation. Although a size distribution of micro-bubbles should be taken into account to improve accuracy in numerical simulations of flows with micro-bubbles, a variety of the size distribution makes it difficult to introduce the size distribution in the simulations. On the other hand, several models such as the Rosin-Rammler equation and the Nukiyama-Tanazawa equation have been proposed to represent the size distribution of particles or droplets. Applicability of these models to the size distribution of micro-bubbles has not been examined yet. In this study, we therefore measure size distribution of micro-bubbles generated by a pressurized dissolution method by using a phase Doppler anemometry (PDA), and investigate the applicability of the available models to the size distributions of micro-bubbles. Experimental apparatus consists of a pressurized tank in which air is dissolved in liquid under high pressure condition, a decompression nozzle in which micro-bubbles are generated due to pressure reduction, a rectangular duct and an upper tank. Experiments are conducted for several liquid volumetric fluxes in the decompression nozzle. Measurements are carried out at the downstream region of the decompression nozzle and in the upper tank. The experimental results indicate that (1) the Nukiyama-Tanasawa equation well represents the size distribution of micro-bubbles generated by the pressurized dissolution method, whereas the Rosin-Rammler equation fails in the representation, (2) the bubble size distribution of micro-bubbles can be evaluated by using the Nukiyama-Tanasawa equation without individual bubble diameters, when mean bubble diameter and skewness of the bubble distribution are given, and (3) an evaluation method of visibility based on the bubble size distribution and bubble
16. Time-resolved interference imaging of the air disc under an impacting drop
Li, E. Q.; Thoroddsen, S. T.
2015-11-01
Water drop impacting on dry, solid surface, is rapidly decelerated by an air cushion. This thin air layer is formed by lubrication pressure in the gas, which is strong enough to stop the inertia of the drop liquid and deform its bottom tip. The contact of the drop with the solid therefore occurs along a ring, entrapping a central bubble. For very large impact velocities the lubrication pressure becomes large enough to compress the gas. We use the Kirana ultra-high-speed video camera and 50 ns pulsed laser-diodes for interferometric imaging, at time-resolution of 200 ns. We capture the evolution of the air-layer thickness profile over the entire bubble entrapment process. The maximum diameter of the air disc is in perfect agreement with earlier theoretical models, if one uses the bottom radius of curvature of the drop. The air-layer thickness is also in agreement with available theoretical models, if one assumes adiabatic compression of the gas. For the largest impact velocities the air is compressed by more than a factor of 10. Immediately after first contact, the air disc expands rapidly in the vertical. The outer edge of the air-disk forms a kink in the free surface. This kink can move radially outwards just before contact, at speed as large as 50 times the impact velocity.
17. Double Bubble? No Trouble!
ERIC Educational Resources Information Center
Shaw, Mike I.; Smith, Greg F.
1995-01-01
Describes a soap-solution activity involving formation of bubbles encasing the students that requires only readily available materials and can be adapted easily for use with various grade levels. Discusses student learning outcomes including qualitative and quantitative observations and the concept of surface tension. (JRH)
18. The Bubble N10
Gama, D.; Lepine, J.; Wu, Y.; Yuan, J.
2014-10-01
We studied the environment surrounding the infrared bubble N10 in molecular and infrared emission. There is an HII region at the center of this bubble. We investigated J=1-0 transitions of molecules ^{12}CO, ^{13}CO and C^{18}O towards N10. This object was detected by GLIMPSE, a survey carried out between 3.6 and 8.0 μ m. We also analyzed the emission at 24 μ m, corresponding to the emission of hot dust, with a contribution of small grains heated by nearby O stars. Besides, the contribution at 8 μ m is dominated by PAHs (polycyclic aromatic hydrocarbons) excited by radiation from the PDRs of bubbles. In the case of N10, it is proposed that the excess at 4.5 μ m IRAC band indicate an outflow, a signature of early stages of massive star formation. This object was the target of observations at the PMO 13.7 m radio telescope. The bubble N10 presents clumps, from which we can derive physical features through the observed parameters. We also intended to discuss the evolutionary stage of the clumps and their distribution. It can lead us to understand the triggered star formation scenario in this region.
19. The Liberal Arts Bubble
ERIC Educational Resources Information Center
Agresto, John
2011-01-01
The author expresses his doubt that the general higher education bubble will burst anytime soon. Although tuition, student housing, and book costs have all increased substantially, he believes it is still likely that the federal government will continue to pour billions into higher education, largely because Americans have been persuaded that it…
20. THE YOUNG INTERSTELLAR BUBBLE WITHIN THE ROSETTE NEBULA
SciTech Connect
Bruhweiler, F. C.; Bourdin, M. O.; Gull, T. R. E-mail: theodore.r.gull@nasa.go
2010-08-20
We use high-resolution International Ultraviolet Explorer (IUE) data and the interstellar (IS) features of highly ionized Si IV and C IV seen toward the young, bright OB stars of NGC 2244 in the core of the Rosette Nebula to study the physics of young IS bubbles. Two discrete velocity components in Si IV and C IV are seen toward stars in the 6.2 pc radius central cavity, while only a single velocity component is seen toward those stars in the surrounding H II region, at the perimeter and external to this cavity. The central region shows characteristics of a very young, windblown bubble. The shell around the central hot cavity is expanding at 56 km s{sup -1} with respect to the embedded OB stars, while the surrounding H II region of the Rosette is expanding at {approx}13 km s{sup -1}. Even though these stars are quite young ({approx}2-4 Myr), both the radius and expansion velocity of the 6.2 pc inner shell point to a far younger age; t{sub age} {approx} 6.4 x 10{sup 4} years. These results represent a strong contradiction to theory and present modeling, where much larger bubbles are predicted around individual O stars and O associations. Specifically, the results for this small bubble and its deduced age extend the 'missing wind luminosity problem' to young evolving bubbles. These results indicate that OB star winds mix the surrounding H II regions and the wind kinetic energy is converted to turbulence and radiated away in the dense H II regions. These winds do not form hot, adiabatically expanding cavities. True IS bubbles appear only to form at later evolutionary times, perhaps triggered by increased mass loss rates or discrete ejection events. Means for rectifying discrepancies between theory and observations are discussed.
1. Bubble-Turbulence Interaction in Binary Fluids
F, Battista; M, Froio; F, Picano; P, Gualtieri; M, Casciola C.
2011-12-01
Multiphase flows represent a central issue in many natural, biological and industrial fields. For instance, liquid jets vaporization, petroleum refining and boiling, emulsions in pharmaceutical applications, are all characterized by a disperse phase, such as solid particles or liquid bubbles, which evolve in a Newtonian carrier fluid. Features such as the global evaporation rates of liquid fuels in air or the homogeneity of the emulsions are controlled by the finest interaction details occurring between the two phases. In this paper we study the rising motion of a bubble induced by buoyancy in a viscous fluid. Usually this issue is tackled by tracking the bubble interface by means of sharp interface methods. However this approach requires "ad hoc" techniques to describe changes in the topological features of the deforming interface and to enforce the mass preservation. Here the problem is addressed by using a different philosophy based on a diffuse interface method, that allows a straightforward analysis of complex phenomena such as bubbles coalescence and break up without any numerical expedient. The model we adopt, funded on a solid thermodynamical and physical base, relies on the Cahn-Hilliard equation for the disperse phase, see Cahn & Hilliard (1958) and Elliott & Songmu (1986).
2. Linear oscillation of gas bubbles in a viscoelastic material under ultrasound irradiation
Hamaguchi, Fumiya; Ando, Keita
2015-11-01
Acoustically forced oscillation of spherical gas bubbles in a viscoelastic material is studied through comparisons between experiments and linear theory. An experimental setup has been designed to visualize bubble dynamics in gelatin gels using a high-speed camera. A spherical gas bubble is created by focusing an infrared laser pulse into (gas-supersaturated) gelatin gels. The bubble radius (up to 150 μm) under mechanical equilibrium is controlled by gradual mass transfer of gases across the bubble interface. The linearized bubble dynamics are studied from the observation of spherical bubble oscillation driven by low-intensity, planar ultrasound driven at 28 kHz. It follows from the experiment for an isolated bubble that the frequency response in its volumetric oscillation was shifted to the high frequency side and its peak was suppressed as the gelatin concentration increases. The measurement is fitted to the linearized Rayleigh-Plesset equation coupled with the Voigt constitutive equation that models the behavior of linear viscoelastic solids; the fitting yields good agreement by tuning unknown values of the viscosity and rigidity, indicating that more complex phenomena including shear thinning, stress relaxation, and retardation do not play an important role for the small-amplitude oscillations. Moreover, the cases for bubble-bubble and bubble-wall systems are studied. The observed interaction effect on the linearized dynamics can be explained as well by a set of the Rayleigh-Plesset equations coupled through acoustic radiation among these systems. This suggests that this experimental setup can be applied to validate the model of bubble dynamics with more complex configuration such as a cloud of bubbles in viscoelastic materials.
3. Linear oscillation of gas bubbles in a viscoelastic material under ultrasound irradiation
SciTech Connect
Hamaguchi, Fumiya; Ando, Keita
2015-11-15
Acoustically forced oscillation of spherical gas bubbles in a viscoelastic material is studied through comparisons between experiments and linear theory. An experimental setup has been designed to visualize bubble dynamics in gelatin gels using a high-speed camera. A spherical gas bubble is created by focusing an infrared laser pulse into (gas-supersaturated) gelatin gels. The bubble radius (up to 150 μm) under mechanical equilibrium is controlled by gradual mass transfer of gases across the bubble interface. The linearized bubble dynamics are studied from the observation of spherical bubble oscillation driven by low-intensity, planar ultrasound driven at 28 kHz. It follows from the experiment for an isolated bubble that the frequency response in its volumetric oscillation was shifted to the high frequency side and its peak was suppressed as the gelatin concentration increases. The measurement is fitted to the linearized Rayleigh–Plesset equation coupled with the Voigt constitutive equation that models the behavior of linear viscoelastic solids; the fitting yields good agreement by tuning unknown values of the viscosity and rigidity, indicating that more complex phenomena including shear thinning, stress relaxation, and retardation do not play an important role for the small-amplitude oscillations. Moreover, the cases for bubble-bubble and bubble-wall systems are studied. The observed interaction effect on the linearized dynamics can be explained as well by a set of the Rayleigh–Plesset equations coupled through acoustic radiation among these systems. This suggests that this experimental setup can be applied to validate the model of bubble dynamics with more complex configuration such as a cloud of bubbles in viscoelastic materials.
4. Synchrotron quantification of ultrasound cavitation and bubble dynamics in Al-10Cu melts.
PubMed
Xu, W W; Tzanakis, I; Srirangam, P; Mirihanage, W U; Eskin, D G; Bodey, A J; Lee, P D
2016-07-01
Knowledge of the kinetics of gas bubble formation and evolution under cavitation conditions in molten alloys is important for the control casting defects such as porosity and dissolved hydrogen. Using in situ synchrotron X-ray radiography, we studied the dynamic behaviour of ultrasonic cavitation gas bubbles in a molten Al-10 wt%Cu alloy. The size distribution, average radius and growth rate of cavitation gas bubbles were quantified under an acoustic intensity of 800 W/cm(2) and a maximum acoustic pressure of 4.5 MPa (45 atm). Bubbles exhibited a log-normal size distribution with an average radius of 15.3 ± 0.5 μm. Under applied sonication conditions the growth rate of bubble radius, R(t), followed a power law with a form of R(t)=αt(β), and α=0.0021 &β=0.89. The observed tendencies were discussed in relation to bubble growth mechanisms of Al alloy melts. PMID:26964960
5. Growth and structural determination of He bubbles in iron/chromium alloys using molecular dynamics simulations
Abhishek, A.; Warrier, M.; Ganesh, R.; Caro, A.
2016-04-01
Helium(He) produced by transmutation process inside structural material due to neutron irradiation plays a vital role in the degradation of material properties. We have carried out Molecular dynamics(MD) simulations to study the growth of He bubble in Iron-Chromium alloy. Simulations are carried out at two different temperatures, viz. 0.1 K and 800 K, upto He bubble radius of 2.5 nm. An equation for variation of volume of He bubbles with the number of He atoms is obtained at both the temperatures. Bubble pressure and potential energy variation is obtained with increasing bubble radius. Dislocations are also found to be emitted after the bubble reaches a critical radius of 0.39 nm at 800 K. Separate MD simulations of He with pre-created voids are also carried out to study the binding energies of He and Vacancy (V) to Hem-Vn cluster. Binding energies are found to be in the range of 1-5.5 eV.
6. Micro bubble formation and bubble dissolution in domestic wet central heating systems
2012-04-01
16 % of the carbon dioxide emissions in the UK are known to originate from wet domestic central heating systems. Contemporary systems make use of very efficient boilers known as condensing boilers that could result in efficiencies in the 90-100% range. However, research and development into the phenomenon of micro bubbles in such systems has been practically non-existent. In fact, such systems normally incorporate a passive deaerator that is installed as a default' feature with no real knowledge as to the micro bubble characteristics and their effect on such systems. High saturation ratios are known to occur due to the widespread use of untreated tap water in such systems and due to the inevitable leakage of air into the closed loop circulation system during the daily thermal cycling. The high temperatures at the boiler wall result in super saturation conditions which consequently lead to micro bubble nucleation and detachment, leading to bubbly two phase flow. Experiments have been done on a test rig incorporating a typical 19 kW domestic gas fired boiler to determine the expected saturation ratios and bubble production and dissolution rates in such systems.
7. Bubbly Little Star
NASA Technical Reports Server (NTRS)
2007-01-01
In this processed Spitzer Space Telescope image, baby star HH 46/47 can be seen blowing two massive 'bubbles.' The star is 1,140 light-years away from Earth.
The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are formed by starlight scattered by surrounding dust.
These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. The red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.
Whenever astronomers observe a star, or snap a stellar portrait, through the lens of any telescope, they know that what they are seeing is slightly blurred. To clear up the blurring in Spitzer images, astronomers at the Jet Propulsion Laboratory developed an image processing technique for Spitzer called Hi-Res deconvolution.
This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When scientists applied this image processing technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.
This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.
8. Characterization of acoustic emissions resulting from particle collision with a stationary bubble.
PubMed
Zhang, Wen; Spencer, Steven J; Coghill, Peter
2013-05-01
The present work characterizes the acoustic emissions resulting from the collision of a particle driven under gravity with a captive bubble. Conventional methods to investigate the bubble particle collision interaction model measure a descriptive parameter known as the collision time. During such a collision, particle impact may cause a strong deformation and a following oscillation of the bubble-particle interface generates detectable passive acoustic emissions (AE). Experiments and models presented show that the AE frequency monotonically decreases with the particle radius and is independent of the impact velocity, whereas the AE amplitude has a more complicated relationship with impact parameters. PMID:23654360
9. The derivation of thermal relaxation time between two-phase bubbly flow
2006-03-01
Thermal relaxation time constant is derived analytically for the relaxed model with unequal phase-temperatures of a vapour bubble at saturation temperature and a non-steady temperature field around the growing vapour bubble. The energy and state equation are solved between two finite boundary conditions. Thermal relaxation time perform a good agreement with Mohammadein (in Doctoral thesis, PAN, Gdansk, 1994) and Moby Dick experiment in terms of non-equilibrium homogeneous model (Bilicki et al. in Proc R Soc Lond A428:379-397, 1990) for lower values of initial void fraction. Thermal relaxation is affected by Jacob number, superheating, initial bubble radius and thermal diffusivity.
10. The dissolution or growth of a gas bubble inside a drop in zero gravity
NASA Technical Reports Server (NTRS)
Kondos, Pericles A.; Subramanian, R. Shankar; Weinberg, Michael C.
1987-01-01
The radius-time history of a gas bubble located concentrically within a spherical liquid drop in a space laboratory is analyzed within the framework of the quasi-stationary approximation. Illustrative results are calculated from the theory which demonstrate interesting qualitative features. For instance, when a pure gas bubble dissolves within a liquid drop in an environment containing the same gas and some inert species, the dissolution can be more or less rapid than that in an unbounded liquid depending on the initial relative size of the drop. Further, given a similar growth situation, indefinite growth is not possible, and the bubble will initially grow, but always dissolve in the end.
11. Sounds of marine seeps: a study of bubble activity near a rigid boundary.
PubMed
Maksimov, A O; Burov, B A; Salomatin, A S; Chernykh, D V
2014-09-01
A passive acoustic method for detecting environmentally dangerous gas leaks from pipelines and methane naturally leaking from the seabed has been investigated. Gas escape involves the formation and release of bubbles of different sizes. Each bubble emits a sound at a specific frequency. Determination of the bubble radius from the frequency of its signature passive acoustic emission by use of so-called Minnaert formula has a restricted area of applicability near the seabed. The point is that the inertial mass and the damping constant of the birthing bubble are markedly different from those of a free bubble. The theoretical model for the bubble volume oscillations near the seabed has been proposed and an analytical solution has been derived. It was shown that the bispherical coordinates provide separation of variables and are more suitable for analysis of the volume oscillations of these constrained bubbles. Explicit formulas have been derived, which describe the dependence of the bubble emission near a rigid wall on its size and the separation distance between the bubble and the boundary. PMID:25190382
12. Scalewise investigation of two-phase flow turbulence in upward turbulent bubbly pipe flows
Lee, Jun Ho; Kim, Hyunseok; Park, Hyungmin
2015-11-01
In the present study, the two-phase flow turbulence in upward turbulent bubbly pipe flows (at the Reynolds number of 5300) is invesgitated, especially focusing on the changes in flow structures with bubbles depending on the length scales. For the scalewise investigation, we perform the wavelet multi-resolution analysis on the velocity fields at three streamwise locations, measured with high-speed two-phase particle image velocimetry technology. While we intentaionlly introduce asymmetrically distributed bubbles at the pipe inlet, the mean volume void fraction is varied from from 0.3% to 1.86% and the considered mean bubble diameter is roughly maintained at 3.8 mm. With the present condition, turbulence enhancement is achieived for most cases but the turbulent suppression is also captured near the wall for the smallest void fraction case. Comparing the scalewise energy contribution, it is understood that the flow structures with length scales between bubble radius and bubble wake size are enhanced due to bubbles, resulting in the turbulence enhancement. On the other hand, flow structure with smaller length scales (mostly existing near the wall) may decrease depending on the bubble condition, which may be one of the explanations in turbulence suppression with bubbles. Supported by the NRF grant funded by the Korea government (NRF-2012M2A8A4055647) via SNU-IAMD.
13. Dynamic features of a laser-induced cavitation bubble near a solid boundary.
PubMed
Yang, Yuan Xiang; Wang, Qian Xi; Keat, T S
2013-07-01
This paper deals with detailed features of bubble dynamics near a solid boundary. The cavitation bubble was created by using a Q-switched Nd: YAG laser pulse and observed using a high-speed camera (up to 100,000 frames per second). A hydrophone system was employed to monitor the acoustic signals generated by the transient pressure impulses and estimate the bubble oscillation periods. Experimental observations were carried out for bubbles with various maximum expanded radius Rmax (between 1.0mm and 1.6mm) and stand-off distances, ds (defined as the distance between the solid boundary and the bubble center at inception) of 0.4≤γ≤3.0, and γ=ds/Rmax. The existence of a solid boundary created asymmetry in the flow field and forced the bubble to collapse non-spherically, which finally brought forth the jet impact phenomenon. The dimensionless first and second oscillation periods were dependent on γ. A series of expansion and collapse of the bubble with cascading loss of energy were observed after the bubble had been generated. This study revealed that most bubbles lost about two-thirds of the total energy from the first maximum expansion to the second maximum expansion. PMID:23411165
14. Radial oscillation of a gas bubble in a fluid as a problem in canonical perturbation theory
Stephens, James
2006-11-01
The oscillation of a gas bubble is in a fluid is of interest in many areas of physics and technology. Lord Rayleigh treated the pressure developed in the collapse of cavitation bubbles and developed an expression for the collapse period. Minnaert developed a harmonic oscillator approximation to bubble oscillation in his study of the sound produced by running water. Besides recent interest in bubble oscillation in connection to sonoluminescence, an understanding of oscillating bubbles is of important to oceanographers studying the sound spectrum produced by water waves, geophysicists employing air guns as acoustic probes, mechanical engineers concerned with erosion of turbine blades, and military engineers concerned with the acoustic signatures developed by the propeller screws of ships and submarines. For the oceanographer, Minnaert's approximation is useful, for the latter two examples, Lord Rayleigh's analysis is appropriate. For the case of the airgun, a period of twice Rayleigh's period for the total collapse'' of the cavitation bubble is often cited as a good approximation for the period of an air bubble ejected from an air gun port, typically at ˜2000 psi), however for the geophysical example, numerical integration is employed from the outset to determine the dynamics of the bubble and the emitted acoustic energy. On the one hand, a bubble can be treated as a harmonic oscillator in the small amplitude regime, whereas even in the relatively moderate pressure regime characteristic of air guns the oscillation is strongly nonlinear and amplitude dependent. Is it possible to develop an analytic approximation that affords insight into the behavior of a bubble beyond the harmonic approximation of Minnaert? In this spirit, the free radial oscillation of a gas bubble in a fluid is treated as a problem in canonical perturbation theory. Several orders of the expansion are determined in order to explore the dependence of the oscillation frequency with bubble amplitude
15. The living times of bubbles at the interface
Cameron, Benjamin; Bourouiba, Lydia; Vandenberghe, Nicolas; Villermaux, Emmanuel
2014-11-01
The lifetime of a water bubble at the surface of a pool prior to its burst remains an open question. It is known that the death of a bubble is initiated by the nucleation of a hole in its shell. However, the mechanisms governing the occurrence of such nucleation sites and prescribing the lifetime of bubbles remain unclear. Combining original visualizations, quantitative measurements of bubbles lifetimes and simple theoretical ideas, we report direct observations of the onset of the bursting process and rationalize the link between the rich interfacial events leading to the hole nucleation on the shell and the resulting robust bubble lifetimes distributions. These play a critical role in shaping the final size distribution of the droplets emitted. We will underline the consequences of the process in the sensible world, like air-sea water vapor exchanges. Bubbles bursting at the surface of water sources also allow for high levels of contamination and long-term exposure to a range of respiratory human pathogens and irritants indoors. Indeed, the droplets created by such bursts can contribute to the transfer of pathogens to the air, followed by their dispersal, thus bridging this subtle problem with unexpected new areas in health. Thanks to the financial support of the MISTI-FRANCE MIT program.
16. Introductory Applicaton of Defocusing DPIV to the Study of Bubbly Shear Flows
Pereira, Francisco; Gharib, Morteza; Dabiri, Dana; Modarress, Darius
1999-11-01
A study of a three-dimensional bubbly flow is presented to demonstrate the applicability of the newly developed defocusing digital particle image velocimetry technique. The DDPIV instrument provides bubble size and location information within a one cubic foot volume. A three-dimensional two-phase flow measurement is performed to obtain a full-field quantitative description of the global dynamics of air bubbles in a vortical shear flow generated by a model boat propeller. Clouds of sub-millimeter air bubbles are injected upstream the propeller. The velocity field is calculated from volumetric cross-correlation of consecutive three-dimensional sets of bubble locations, whereas the bubble size information is estimated from the blurred image of bubbles. Flow analysis is presented in terms of vorticity and bubble trajectory. The bubble size distribution upstream and downstream the propeller is discussed. Growth and collapse of bubbles are detected and related to the respective velocity field in the suction and high-pressure regions of the propeller.
17. Resolving size distributions of bubbles with radii less than 30 μm with optical and acoustical methods
Czerski, H.; Twardowski, M.; Zhang, X.; Vagle, S.
2011-07-01
Many studies have investigated bubble size distributions in the ocean, but the measured size range does not normally extend to bubbles with a radius below 20 μm. Bubbles smaller than this are thought to have a significant effect on the optical properties of the ocean, potentially affecting remotely sensed measurements of ocean color and the optical detection of particulates and dissolved matter. Such optical data are becoming the major source of oceanic information about algal blooms, primary productivity, sediment loading and the spread of pollutants. The challenges associated with measuring these bubbles are difficulty of calibrating sensors with independent bubble size measurements and lack of knowledge about the organic coating on the bubbles. This paper describes simultaneous oceanic measurements of these small bubbles using independent optical and acoustical techniques. These measurements agree well, and an investigation of the bubble coating parameters was made. Both the optical and acoustical properties of bubbles are affected by this organic coating, and a comparison of these measurements narrows down the choice of possible coating parameters. Our results suggest that the bubbles measured in this study were likely to have a coating with a thickness of 10 nm and a refractive index of 1.18, and that the coating thickness is the more important parameter for optical inversions. The research described here is the first attempt to constrain these parameters in the ocean using two independent techniques and suggests that further studies of this type could result in significant insight into oceanic bubble coatings.
18. Stabilizing effect of plasma discharge on bubbling fluidized granular bed
Hu, Mao-Bin; Dang, Sai-Chao; Ma, Qiang; Xia, Wei-Dong
2015-07-01
Fluidized beds have been widely used for processing granular materials. In this paper, we study the effect of plasma on the fluidization behavior of a bubbling fluidized bed with an atmospheric pressure plasma discharger. Experiment results show that the bubbling fluidized bed is stabilized with the discharge of plasma. When the discharge current reaches a minimum stabilization current Cms, air bubbles in the bed will disappear and the surface fluctuation is completely suppressed. A simplified model is proposed to consider the effect of electric Coulomb force generated by the plasma. It is found that the Coulomb force will propel the particles to move towards the void area, so that the bubbling fluidized bed is stabilized with a high enough plasma discharge. Project supported by the National Natural Science Foundation of China (Grant Nos. 11035005 and 11034010).
19. Numerical simulations of bubble dynamics at high Reynolds numbers
Piedra, Saul; Ramos, Eduardo; Termociencias Team
2012-11-01
We present a three-dimensional numerical simulation of air bubbles rising in water. The analysis is based on the solution of the conservation equations combined with a front tracking method to represent an interface between two immiscible fluids. The interfacial forces incorporate the effect of the surface tension and the material properties of the fluids are calculated in the entire integration domain. In order to follow the bubbles along thousands of diameters in its ascending motion, a moving reference frame technique is used. The shape of the bubbles, the pressure and the velocity fields at different flow conditions calculated with our model are in agreement with experimental observations reported in the literature. Also, the qualitative change in the trajectory of the bubbles from rectilinear to zig-zag to helical motion is reproduced by the model. Dominant physical effects in each mode of displacement are described. S.P. acknowledges support from CONACYT-Mexico through a PhD grant.
20. Can bubbles sink ships?
Hueschen, Michael A.
2010-02-01
I investigate the interplay between the buoyancy force and the upwelling (or drag) force which act on a floating object when bubbles are rising through a body of water. Bubbles reduce the buoyant force by reducing the density of the water, but if they entrain an upwelling flow of water as they rise, they can produce a large upward drag force on the floating object. In an upwelling flow, our model ship (density=0.94 g/cm3) floats in a foam whose density is only 0.75 g/cm3. Comparing results with and without upwelling currents is an interesting demonstration and has real-world applications to ships in the ocean.
1. CONTINUOUSLY SENSITIVE BUBBLE CHAMBER
DOEpatents
Good, R.H.
1959-08-18
A radiation detector of the bubble chamber class is described which is continuously sensitive and which does not require the complex pressure cycling equipment characteristic of prior forms of the chamber. The radiation sensitive element is a gas-saturated liquid and means are provided for establishing a thermal gradient across a region of the liquid. The gradient has a temperature range including both the saturation temperature of the liquid and more elevated temperatures. Thus a supersaturated zone is created in which ionizing radiations may give rise to visible gas bubbles indicative of the passage of the radiation through the liquid. Additional means are provided for replenishing the supply of gas-saturated liquid to maintaincontinuous sensitivity.
2. Effect of electrolytes on bubble coalescence in columns observed with visualization techniques.
PubMed
Aguilera, María Eugenia; Ojeda, Antonieta; Rondón, Carolina; López De Ramos, Aura
2002-10-01
Bubble coalescence and the effect of electrolytes on this phenomenon have been previously studied. This interfacial phenomenon has attracted attention for reactor design/operation and enhanced oil recovery. Predicting bubble coalescence may help prevent low yields in reactors and predict crude oil recovery. Because of the importance of bubble coalescence, the objectives of this work were to improve the accuracy of measuring the percentage of coalescing bubbles and to observe the interfacial gas-liquid behavior. An experimental setup was designed and constructed. Bubble interactions were monitored with a visualization setup. The percentage of air bubble coalescence was 100% in distilled water, about 50% in 0.1 M sodium chloride (NaCl) aqueous solution, and 0% in 0.145 M NaCl aqueous solution. A reduction of the contact gas-liquid area was observed in distillate water. The volume of the resulting bubble was the sum of the original bubble volumes. Repulsion of bubbles was observed in NaCl solutions exceeding 0.07 M. The percentage of bubble coalescence diminishes as the concentration of NaCl chloride increases. High-speed video recording is an accurate technique to measure the percentage of bubble coalescence, and represents an important advance in gas-liquid interfacial studies. PMID:12496024
3. Effects of Gravity on Sheared Turbulence Laden with Bubbles or Droplets
NASA Technical Reports Server (NTRS)
Elghobashi, Said; Lasheras, Juan
1999-01-01
The objective of this numerical/experimental study is to improve the understanding of the effects of gravity on the two-way interaction between dispersed particles (bubbles or liquid droplets) and the carrier turbulent flow. The first phase of the project considers isotropic turbulence. Turbulent homogeneous shear flows laden with droplets/bubbles will be studied in the next phase. The experiments reported here are concerned with the dispersion of liquid droplets by homogeneous turbulence under various gravitational conditions and the effect of these droplets on the evolution of the turbulence of the carrier fluid (air). Direct numerical simulations (DNS) of bubble - laden isotropic decaying turbulence are performed using the two-fluid approach (TF) instead of the Eulerian-Lagrangian approach (EL). The motivation for using the TF formulation is that EL requires considerable computational resources especially for the case of two-way coupling where the instantaneous trajectories of a large number of individual bubbles need to be computed. The TF formulation is developed by spatially averaging the instantaneous equations of the carrier flow and bubble phase over a scale of the order of the Kolmogorov length scale which, in our case, is much larger than the bubble diameter. On that scale, the bubbles are treated as a continuum (without molecular diffusivity) characterized by the bubble phase velocity field and concentration (volume fraction). The bubble concentration, C, is assumed small enough to neglect the bubble-bubble interactions.
4. Magnetic bubble domain memories
NASA Technical Reports Server (NTRS)
Ypma, J. E.
1974-01-01
Some attractive features of Bubble Domain Memory and its relation to existing technologies are discussed. Two promising applications are block access mass memory and tape recorder replacement. The required chip capabilities for these uses are listed, and the specifications for a block access mass memory designed to fit between core and HPT disk are presented. A feasibility model for a tape recorder replacement is introduced.
5. Slurry bubble column hydrodynamics
Slurry bubble column reactors are presently used for a wide range of reactions in both chemical and biochemical industry. The successful design and scale up of slurry bubble column reactors require a complete understanding of multiphase fluid dynamics, i.e. phase mixing, heat and mass transport characteristics. The primary objective of this thesis is to improve presently limited understanding of the gas-liquid-solid slurry bubble column hydrodynamics. The effect of superficial gas velocity (8 to 45 cm/s), pressure (0.1 to 1.0 MPa) and solids loading (20 and 35 wt.%) on the time-averaged solids velocity and turbulent parameter profiles has been studied using Computer Automated Radioactive Particle Tracking (CARPT). To accomplish this, CARPT technique has been significantly improved for the measurements in highly attenuating systems, such as high pressure, high solids loading stainless steel slurry bubble column. At a similar set of operational conditions time-averaged gas and solids holdup profiles have been evaluated using the developed Computed Tomography (CT)/Overall gas holdup procedure. This procedure is based on the combination of the CT scans and the overall gas holdup measurements. The procedure assumes constant solids loading in the radial direction and axially invariant cross-sectionally averaged gas holdup. The obtained experimental holdup, velocity and turbulent parameters data are correlated and compared with the existing low superficial gas velocities and atmospheric pressure CARPT/CT gas-liquid and gas-liquid-solid slurry data. The obtained solids axial velocity radial profiles are compared with the predictions of the one dimensional (1-D) liquid/slurry recirculation phenomenological model. The obtained solids loading axial profiles are compared with the predictions of the Sedimentation and Dispersion Model (SDM). The overall gas holdup values, gas holdup radial profiles, solids loading axial profiles, solids axial velocity radial profiles and solids
6. Bubble dynamics in drinks
Broučková, Zuzana; Trávníček, Zdeněk; Šafařík, Pavel
2014-03-01
This study introduces two physical effects known from beverages: the effect of sinking bubbles and the hot chocolate sound effect. The paper presents two simple "kitchen" experiments. The first and second effects are indicated by means of a flow visualization and microphone measurement, respectively. To quantify the second (acoustic) effect, sound records are analyzed using time-frequency signal processing, and the obtained power spectra and spectrograms are discussed.
7. A model of the interaction of bubbles and solid particles under acoustic excitation
Hay, Todd Allen
The Lagrangian formalism utilized by Ilinskii, Hamilton and Zabolotskaya [J. Acoust. Soc. Am. 121, 786-795 (2007)] to derive equations for the radial and translational motion of interacting bubbles is extended here to obtain a model for the dynamics of interacting bubbles and elastic particles. The bubbles and particles are assumed to be spherical but are otherwise free to pulsate and translate. The model is accurate to fifth order in terms of a nondimensional expansion parameter R/d, where R is a characteristic radius and d is a characteristic distance between neighboring bubbles or particles. The bubbles and particles may be of nonuniform size, the particles elastic or rigid, and external acoustic sources are included to an order consistent with the accuracy of the model. Although the liquid is assumed initially to be incompressible, corrections accounting for finite liquid compressibility are developed to first order in the acoustic Mach number for a cluster of bubbles and particles, and to second order in the acoustic Mach number for a single bubble. For a bubble-particle pair consideration is also given to truncation of the model at fifth order in R/d via automated derivation of the model equations to arbitrary order. Numerical simulation results are presented to demonstrate the effects of key parameters such as particle density and size, liquid compressibility, particle elasticity and model order on the dynamics of single bubbles, pairs of bubbles, bubble-particle pairs and clusters of bubbles and particles under both free response conditions and sinusoidal or shock wave excitation.
8. Segregating gas from melt: an experimental study of the Ostwald ripening of vapor bubbles in magmas
USGS Publications Warehouse
Lautze, Nicole C.; Sisson, Thomas W.; Mangan, Margaret T.; Grove, Timothy L.
2011-01-01
Diffusive coarsening (Ostwald ripening) of H2O and H2O-CO2 bubbles in rhyolite and basaltic andesite melts was studied with elevated temperature–pressure experiments to investigate the rates and time spans over which vapor bubbles may enlarge and attain sufficient buoyancy to segregate in magmatic systems. Bubble growth and segregation are also considered in terms of classical steady-state and transient (non-steady-state) ripening theory. Experimental results are consistent with diffusive coarsening as the dominant mechanism of bubble growth. Ripening is faster in experiments saturated with pure H2O than in those with a CO2-rich mixed vapor probably due to faster diffusion of H2O than CO2 through the melt. None of the experimental series followed the time1/3 increase in mean bubble radius and time-1 decrease in bubble number density predicted by classical steady-state ripening theory. Instead, products are interpreted as resulting from transient regime ripening. Application of transient regime theory suggests that bubbly magmas may require from days to 100 years to reach steady-state ripening conditions. Experimental results, as well as theory for steady-state ripening of bubbles that are immobile or undergoing buoyant ascent, indicate that diffusive coarsening efficiently eliminates micron-sized bubbles and would produce mm-sized bubbles in 102–104 years in crustal magma bodies. Once bubbles attain mm-sizes, their calculated ascent rates are sufficient that they could transit multiple kilometers over hundreds to thousands of years through mafic and silicic melt, respectively. These results show that diffusive coarsening can facilitate transfer of volatiles through, and from, magmatic systems by creating bubbles sufficiently large for rapid ascent.
9. Energy analysis during acoustic bubble oscillations: relationship between bubble energy and sonochemical parameters.
PubMed
Merouani, Slimane; Hamdaoui, Oualid; Rezgui, Yacine; Guemini, Miloud
2014-01-01
In this work, energy analysis of an oscillating isolated spherical bubble in water irradiated by an ultrasonic wave has been theoretically studied for various conditions of acoustic amplitude, ultrasound frequency, static pressure and liquid temperature in order to explain the effects of these key parameters on both sonochemistry and sonoluminescence. The Keller-Miksis equation for the temporal variation of the bubble radius in compressible and viscous medium has been employed as a dynamics model. The numerical calculations showed that the rate of energy accumulation, dE/dt, increased linearly with increasing acoustic amplitude in the range of 1.5-3.0 atm and decreased sharply with increasing frequency in the range 200-1000 kHz. There exists an optimal static pressure at which the power w is highest. This optimum shifts toward a higher value as the acoustic amplitude increases. The energy of the bubble slightly increases with the increase in liquid temperature from 10 to 60 °C. The results of this study should be a helpful means to explain a variety of experimental observations conducted in the field of sonochemistry and sonoluminescence concerning the effects of operational parameters. PMID:23683796
10. Mechanisms of gas bubble retention
SciTech Connect
Gauglitz, P.A.; Mahoney, L.A.; Mendoza, D.P.; Miller, M.C.
1994-09-01
Retention and episodic release of flammable gases are critical safety concerns regarding double-shell tanks (DSTs) containing waste slurries. Previous investigations have concluded that gas bubbles are retained by the slurry that has settled at the bottom of the DST. However, the mechanisms responsible for the retention of these bubbles are not well understood. In addition, the presence of retained gas bubbles is expected to affect the physical properties of the sludge, but essentially no literature data are available to assess the effect of these bubbles. The rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles. The objectives of this study are to elucidate the mechanisms contributing to gas bubble retention and release from sludge such as is in Tank 241-SY-101, understand how the bubbles affect the physical properties of the sludge, develop correlations of these physical properties to include in computer models, and collect experimental data on the physical properties of simulated sludges with bubbles. This report presents a theory and experimental observations of bubble retention in simulated sludge and gives correlations and new data on the effect of gas bubbles on sludge yield strength.
11. Spreading of Bubbles after Contacting the Lower Side of an Aerophilic Slide Immersed in Water.
PubMed
de Maleprade, Hélène; Clanet, Christophe; Quéré, David
2016-08-26
While the dynamics of complete wetting has been widely studied for liquids, the way a gas spreads on a solid is by far less known. We report here the events following the rise of a millimeter-size air bubble towards a textured material immersed in water and covered by a thin plastron of air. Bubbles contact the material either directly at the end of the rise, or after a few rebounds, which affects the initial shape of the bubble and the resulting dynamics of contact. Then, air spreads on the material, owing to surface tension and later buoyance, which tends to flatten further the bubble. The corresponding dynamics are shown to result from the inertial resistance of water, which explains how spreading bubbles reach centimeter sizes in typically 10 ms. PMID:27610858
12. Chondromyxoid Fibroma of Radius: A Case Report
PubMed Central
Bagewadi, Rajakumar M.; Hippargi, Surekha B.
2016-01-01
Chondromyxoid fibroma (CMF) is a rare benign cartilaginous tumour accounting to less than 1% of bone tumours. It is most commonly seen in lower extremity involving tibia. CMF of radius is rare. We report a rare case of CMF of proximal radius in a 37-year-old female who presented with swelling and pain over right elbow. Wide local excision of proximal radius along with radial head was done and above elbow POP slab was applied for one month. Elbow range of movement exercises started after one month. PMID:27437232
13. Chondromyxoid Fibroma of Radius: A Case Report.
PubMed
Bagewadi, Rajakumar M; Nerune, Savitri Mallikarjun; Hippargi, Surekha B
2016-05-01
Chondromyxoid fibroma (CMF) is a rare benign cartilaginous tumour accounting to less than 1% of bone tumours. It is most commonly seen in lower extremity involving tibia. CMF of radius is rare. We report a rare case of CMF of proximal radius in a 37-year-old female who presented with swelling and pain over right elbow. Wide local excision of proximal radius along with radial head was done and above elbow POP slab was applied for one month. Elbow range of movement exercises started after one month. PMID:27437232
14. Management of Complications of Distal Radius Fractures
PubMed Central
Chung, Kevin C.; Mathews, Alexandra L.
2015-01-01
Synopsis Treating a fracture of the distal radius may require the surgeon to make a difficult decision between surgical treatment and nonsurgical management. The use of surgical fixation has recently increased owing to complications associated with conservative treatment. However, conservative action may be necessary depending on certain patient factors. The treating surgeon must be aware of the possible complications associated with distal radius fracture treatments to prevent their occurrence. Prevention can be achieved with a proper understanding of the mechanism of these complications. This article discusses the most recent evidence on how to manage and prevent complications following a fracture of the distal radius. PMID:25934197
15. Interfacial characteristic measurements in horizontal bubbly two-phase flow
Wang, Z.; Huang, W. D.; Srinivasmurthy, S.; Kocamustafaogullari, G.
1990-10-01
Advances in the study of two-phase flow increasingly require detailed internal structure information upon which theoretical models can be formulated. The void fraction and interfacial area are two fundamental parameters characterizing the internal structure of two-phase flow. However, little information is currently available on these parameters, and it is mostly limited to vertical flow configurations. In view of the above, the internal phase distribution of concurrent, air-water bubbly flow in a 50.3 mm diameter transparent pipeline has been experimentally investigated by using a double-sensor resistivity probe. Liquid and gas volumetric superficial velocities ranged from 3.74 to 5.60 m/s and 0.25 to 1.59 m/s, respectively, and average void fractions ranged from 2.12 to 22.5 percent. The local values of void fractions, interfacial area concentration, mean bubble diameter, bubble interface velocity, bubble chord-length and bubble frequency distributions were measured. The experimental results indicate that the void fraction interfacial area concentration and bubble frequency have local maxima near the upper pipe wall, and the profiles tend to flatten with increasing void fraction. The observed peak void fraction can reach 0.65, the peak interfacial area can go up to 900 approximately 1000 sq m/cu m, and the bubble frequency can reach a value of 2200 per s. These ranges of values have never been reported for vertical bubbly flow. It is found that either decreasing the liquid flow rate or increasing the gas flow would increase the local void fraction, the interfacial area concentration and the bubble frequency.
16. Contributions to the acoustic excitation of bubbles released from a nozzle.
PubMed
Czerski, Helen; Deane, Grant B
2010-11-01
It has recently been demonstrated that air bubbles released from a nozzle are excited into volume mode oscillations by the collapse of the neck of air formed at the moment of bubble detachment. A pulse of sound is caused by these breathing mode oscillations, and the sound of air-entraining flows is made up of many such pulses emitted as bubbles are created. This paper is an elaboration on a JASA-EL paper, which examined the acoustical excitation of bubbles released from a nozzle. Here, further details of the collapse of a neck of air formed at the moment of bubble formation and its implications for the emission of sound by newly formed bubbles are presented. The role of fluid surface tension was studied using high-speed photography and found to be consistent with a simple model for neck collapse. A re-entrant fluid jet forms inside the bubble just after detachment, and its role in acoustic excitation is assessed. It is found that for slowly-grown bubbles the jet does make a noticeable difference to the total volume decrease during neck collapse, but that it is not a dominant effect in the overall acoustic excitation. PMID:21110560
17. Stable Multibubble Sonoluminescence Bubble Patterns
SciTech Connect
Posakony, Gerald J.; Greenwood, Lawrence R.; Ahmed, Salahuddin
2006-06-30
Multibubble standing wave patterns can be generated from a flat piezoceramic transducer element propagating into water. By adding a second transducer positioned at 90 degrees from the transducer generating the standing wave, a 3-dimensional volume of stable single bubbles can be established. Further, the addition of the second transducer stabilizes the bubble pattern so that individual bubbles may be studied. The size of the bubbles and the separation of the standing waves depend on the frequency of operation. Two transducers, operating at frequencies above 500 kHz, provided the most graphic results for the configuration used in this study. At these frequencies stable bubbles exhibit a bright sonoluminescence pattern. Whereas stable SBSL is well-known, stable MBSL has not been previously reported. This paper includes discussions of the acoustic responses, standing wave patterns, and pictorial results of the separation of individual bubble of sonoluminescence in a multibubble sonoluminescence environment.
SciTech Connect
Ripin, B.H.; McLean, E.A.; Manka, C.K.; Pawley, C.; Stamper, J.A.; Peyser, T.A.; Mostovych, A.N.; Grun, J.; Hassam, A.B.; Huba, J.
1987-11-16
We observe linear and nonlinear features of a strong plasma/magnetic field interchange Rayleigh-Taylor instability in the limit of large ion Larmor radius. The instability undergoes rapid linear growth culminating in free-streaming flute tips.
19. Experiments on bubble generation by a hydrofoil moving beneath the water surface for reducing ship drag
Kumagai, Ichiro; Murai, Yuichi; Takahashi, Yoshiaki; Sakamaki, Haruki; Tsukahara, Takahiro; Ozaki, Tsubasa; Tasaka, Yuji; Oishi, Yoshihiko
2014-04-01
We have invented two types of hydrofoil bubble generator for drag reduction of ship that can reduce the energy for air bubble generation on the ship hull. Their fundamental process of air entrainment and subsequent bubble generation by the hydrofoil facility are described by a simple fluid dynamic model. We experimentally determined the critical velocity of the bubble generation and the relationship between air volume flow rate and the hydrofoil velocity. The magnitude of the negative pressure produced above the hydrofoil, which is a driving force of the air entrainment, depends on the shape of the hydrofoil, gap ratio (normalized depth of the hydrofoil), Reynolds number, Froude number, and angle of attack. Recent applications of the drag-reduction technology with air bubbles to a ship save about 10%-15% of the total energy consumption of the ship. The device works as a self-priming pump when the draft of the ship is shallow (< ˜5 m) as predicted by the theory. For ships of deeper draft, the device needs the assistance of an air compressor. Because the magnitude of the negative pressure above the hydrofoil depends on the flow condition around the hydrofoil, proper operation of compressors is necessary. We also show experimental results on optimization of hydrofoils to enhance the hydrofoil performance of air entrainment and air bubble generation.
20. Arthroscopic management of distal radius fractures.
PubMed
Wiesler, Ethan R; Chloros, George D; Mahirogullari, Mahir; Kuzma, Gary R
2006-11-01
Arthroscopy has the advantage of providing a direct and accurate assessment of the articular surfaces and detecting the presence of injuries associated with distal radius fractures. Current indications, although numerous and potentially expanding, also are controversial. This report presents a global view of the current status of arthroscopy in the management of distal radius fractures. The rationale of arthroscopic treatment, the available evidence, and finally the diagnosis and treatment are discussed. PMID:17095385
1. Neutron detection via bubble chambers.
PubMed
Jordan, D V; Ely, J H; Peurrung, A J; Bond, L J; Collar, J I; Flake, M; Knopf, M A; Pitts, W K; Shaver, M; Sonnenschein, A; Smart, J E; Todd, L C
2005-01-01
Research investigating the application of pressure-cycled bubble chambers to fast neutron detection is described. Experiments with a Halon-filled chamber showed clear sensitivity to an AmBe neutron source and insensitivity to a (137)Cs gamma source. Bubble formation was documented using high-speed photography, and a ceramic piezo-electric transducer element registered the acoustic signature of bubble formation. In a second set of experiments, the bubble nucleation response of a Freon-134a chamber to an AmBe neutron source was documented with high-speed photography. PMID:16005238
2. Droplets, Bubbles and Ultrasound Interactions.
PubMed
Shpak, Oleksandr; Verweij, Martin; de Jong, Nico; Versluis, Michel
2016-01-01
The interaction of droplets and bubbles with ultrasound has been studied extensively in the last 25 years. Microbubbles are broadly used in diagnostic and therapeutic medical applications, for instance, as ultrasound contrast agents. They have a similar size as red blood cells, and thus are able to circulate within blood vessels. Perfluorocarbon liquid droplets can be a potential new generation of microbubble agents as ultrasound can trigger their conversion into gas bubbles. Prior to activation, they are at least five times smaller in diameter than the resulting bubbles. Together with the violent nature of the phase-transition, the droplets can be used for local drug delivery, embolotherapy, HIFU enhancement and tumor imaging. Here we explain the basics of bubble dynamics, described by the Rayleigh-Plesset equation, bubble resonance frequency, damping and quality factor. We show the elegant calculation of the above characteristics for the case of small amplitude oscillations by linearizing the equations. The effect and importance of a bubble coating and effective surface tension are also discussed. We give the main characteristics of the power spectrum of bubble oscillations. Preceding bubble dynamics, ultrasound propagation is introduced. We explain the speed of sound, nonlinearity and attenuation terms. We examine bubble ultrasound scattering and how it depends on the wave-shape of the incident wave. Finally, we introduce droplet interaction with ultrasound. We elucidate the ultrasound-focusing concept within a droplets sphere, droplet shaking due to media compressibility and droplet phase-conversion dynamics. PMID:26486337
3. Helium bubble bursting in tungsten
SciTech Connect
Sefta, Faiza; Juslin, Niklas; Wirth, Brian D.
2013-12-28
Molecular dynamics simulations have been used to systematically study the pressure evolution and bursting behavior of sub-surface helium bubbles and the resulting tungsten surface morphology. This study specifically investigates how bubble shape and size, temperature, tungsten surface orientation, and ligament thickness above the bubble influence bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom “islands,” craters, and pinholes. The present study provides insight into the mechanisms and conditions leading to various tungsten topology changes, which we believe are the initial stages of surface evolution leading to the formation of nanoscale fuzz.
4. Bubble Measuring Instrument and Method
NASA Technical Reports Server (NTRS)
Kline-Schoder, Robert (Inventor); Magari, Patrick J. (Inventor)
2002-01-01
Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer. respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.
5. Bubble measuring instrument and method
NASA Technical Reports Server (NTRS)
Kline-Schoder, Robert (Inventor); Magari, Patrick J. (Inventor)
2003-01-01
Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.
6. Bubble Measuring Instrument and Method
NASA Technical Reports Server (NTRS)
Kline-Schoder, Robert (Inventor); Magari, Patrick J. (Inventor)
2002-01-01
Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.
7. Bubble Measuring Instrument and Method
NASA Technical Reports Server (NTRS)
Kline-Schoder, Robert (Inventor); Magari, Patrick J. (Inventor)
2002-01-01
Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting. distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receive, the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.
8. Analysis of the three-dimensional structure of a bubble wake using PIV and Galilean decomposition
SciTech Connect
Hassan, Y.A.; Schmidl, W.D.; Ortiz-Villafuerte, J.; Scharf, J.R.
1999-07-01
Bubbly flow plays a key role in a variety of natural and industrial processes. An accurate and complete description of the phase interactions in two-phase bubbly flow is not available at this time. These phase interactions are, in general, always three-dimensional and unsteady. Therefore, measurement techniques utilized to obtain qualitative and quantitative data from two-phase flow should be able to acquire transient and three-dimensional data, in order to provide information to test theoretical models and numerical simulations. Even for dilute bubble flows, in which bubble interaction is at a minimum, the turbulent motion of the liquid generated by the bubble is yet to be completely understood. For many years, the design of systems with bubbly flows was based primarily on empiricism. Dilute bubbly flows are an extension of single bubble dynamics, and therefore improvements in the description and modeling of single bubble motion, the flow field around the bubble, and the dynamical interactions between the bubble and the flow will consequently improve bubbly flow modeling. The improved understanding of the physical phenomena will have far-reaching benefits in upgrading the operation and efficiency of current processes and in supporting the development of new and innovative approaches. A stereoscopic particle image velocimetry measurement of the flow generated by the passage of a single air-bubble rising in stagnant water, in a circular pipe is presented. Three-dimensional velocity fields within the measurement zone were obtained. Ensemble-averaged instantaneous velocities for a specific bubble path were calculated and interpolated to obtain mean three-dimensional velocity fields. A Galilean velocity decomposition is used to study the vorticity generated in the flow.
9. Bubble Generation in a Continuous Liquid Flow Under Reduced Gravity Conditions
NASA Technical Reports Server (NTRS)
Pais, Salvatore Cezar
1999-01-01
The present work reports a study of bubble generation under reduced gravity conditions for both co-flow and cross-flow configurations. Experiments were performed aboard the DC-9 Reduced Gravity Aircraft at NASA Glenn Research Center, using an air-water system. Three different flow tube diameters were used: 1.27, 1.9, and 2.54 cm. Two different ratios of air injection nozzle to tube diameters were considered: 0.1 and 0.2. Gas and liquid volumetric flow rates were varied from 10 to 200 ml/s. It was experimentally observed that with increasing superficial liquid velocity, the bubbles generated decreased in size. The bubble diameter was shown to increase with increasing air injection nozzle diameters. As the tube diameter was increased, the size of the detached bubbles increased. Likewise, as the superficial liquid velocity was increased, the frequency of bubble formation increased and thus the time to detach forming bubbles decreased. Independent of the flow configuration (for either single nozzle or multiple nozzle gas injection), void fraction and hence flow regime transition can be controlled in a somewhat precise manner by solely varying the gas and liquid volumetric flow rates. On the other hand, it is observed that uniformity of bubble size can be controlled more accurately by using single nozzle gas injection than by using multiple port injection, since this latter system gives rise to unpredictable coalescence of adjacent bubbles. A theoretical model, based on an overall force balance, is employed to study single bubble generation in the dynamic and bubbly flow regime. Under conditions of reduced gravity, the gas momentum flux enhances bubble detachment; however, the surface tension forces at the nozzle tip inhibits bubble detachment. Liquid drag and inertia can act either as attaching or detaching force, depending on the relative velocity of the bubble with respect to the surrounding liquid. Predictions of the theoretical model compare well with performed
10. Vortex dynamics of collapsing bubbles: Impact on the boundary layer measured by chronoamperometry.
PubMed
Reuter, Fabian; Cairós, Carlos; Mettin, Robert
2016-11-01
Cavitation bubbles collapsing in the vicinity to a solid substrate induce intense micro-convection at the solid. Here we study the transient near-wall flows generated by single collapsing bubbles by chronoamperometric measurements synchronously coupled with high-speed imaging. The individual bubbles are created at confined positions by a focused laser pulse. They reach a maximum expansion radius of approximately 425μm. Several stand-off distances to the flat solid boundary are investigated and all distances are chosen sufficiently large that no gas phase of the expanding and collapsing bubble touches the solid directly. With a microelectrode embedded into the substrate, the time-resolved perturbations in the liquid shear layer are probed by means of a chronoamperometric technique. The measurements of electric current are synchronized with high-speed imaging of the bubble dynamics. The perturbations of the near-wall layer are found to result mainly from ring vortices created by the jetting bubble. Other bubble induced flows, such as the jet and flows following the radial bubble oscillations are perceptible with this technique, but show a minor influence at the stand-off distances investigated. PMID:27245968
11. Experimental technique for observing free oscillation of a spherical gas bubble in highly viscous liquids.
Nakajima, Takehiro; Ando, Keita
2015-11-01
An experimental technique is developed to observe free oscillations of a spherical gas bubble in highly viscous liquids. It is demonstrated that focusing a nanosecond laser pulse of wavelength 532 nm and energy up to 1.5 mJ leads to the formation of a spherical gaseous bubble, not a vaporous bubble (quickly condensed back to the liquid), whose equilibrium radius is up to 200 microns in glycerin saturated with gases at room temperature. The subsequent free oscillations of the spherical gas bubble is visualized using a high-speed camera. Since the oscillation periods are short enough to ignore bubble translation under gravity and mass transfer out of the bubble, the observed bubble dynamics can be compared to nonlinear and linearized Reyleigh-Plesset-type calculations that account for heat conduction and acoustic radiation as well as the liquid viscosity. In this presentation, we report on the measurements with varying the viscosity and comparisons to the theory to quantify damping mechanisms in the bubble dynamics.
12. Effect of charge on the dynamics of an acoustically forced bubble
Hongray, Thotreithem; Ashok, B.; Balakrishnan, J.
2014-06-01
The effect of charge on the dynamics of a gas bubble undergoing forced oscillations in a liquid due to incidence of an ultrasonic wave is theoretically investigated. The limiting values of the possible charge a bubble may physically carry are obtained. The presence of charge influences the regime in which the bubble's radial oscillations fall. The extremal compressive and expansive dimensions of the bubble are also studied as a function of the amplitude of the driving pressure. It is shown that the limiting value of the bubble charge is dictated both by the minimal value reachable of the bubble radius as well as the amplitude of the driving ultrasonic pressure wave. A non-dimensional ratio ζ is defined that is a comparative measure of the extremal values the bubble can expand or contract to, and we find the existence of an unstable regime for ζ as a function of the driving pressure amplitude, Ps. This unstable regime is gradually suppressed with increasing bubble size. The Blake and the upper transient pressure thresholds for the system are then discussed.
13. A bubbling bolt
2014-07-01
We present a new solvable system, solving the equations of five-dimensional ungauged = 1 supergravity coupled to vector multiplets, that allows for non-extremal solutions and reduces to a known system when restricted to the floating brane Ansatz. A two-centre globally hyperbolic smooth geometry is obtained as a solution to this system, describing a bubble linking a Gibbons-Hawking centre to a charged bolt. However this solution turns out to violate the BPS bound, and we show that its generalisation to an arbitrary number of Gibbons-Hawking centres never admits a spin structure.
14. Effect of bubble size on micro-bubble drag reduction
Shen, Xiaochun
2005-11-01
The effect of bubble size on micro-bubble drag reduction was investigated experimentally in a high-speed turbulent channel flow of water. A variety of near-wall injection techniques were used to create a bubbly turbulent boundary layer. The resulting wall friction force was measured directly by a floating element force balance. The bubble size was determined from photographic imaging. Using compressed nitrogen to force flow through a slot injector located in the plate beneath the boundary layer of the tunnel test section, a surfactant solution (Triton X-100, 19ppm) and salt water solution (35ppt) generated bubbles of average size between ˜500 microns and ˜200 microns and ˜100 microns, respectively (40 < d^+ < 200). In addition hollow spherical glass beads (˜75 microns (d^+ = 30) and specific gravity 0.18) and previously prepared lipid stabilized gas bubbles of ˜ 30 micron (d^+ =12) were injected. The results indicate that the drag reduction is related strongly to the injected gas volume flux and the static pressure in the boundary layer. Changing bubble size had essentially no influence on the measured friction drag, suggesting that friction drag is not a strong function of bubble size. [Sponsored by the Office of Naval Research.
15. Electrowetting-on-dielectric assisted bubble detachment in a liquid film
Wang, S.; Chen, H. H.; Chen, C. L.
2016-05-01
Drawing inspiration from electrowetting-controlled droplets, the potential advantages of electrowetting for bubble dynamics are investigated experimentally. In this study, we present and characterize an open electrowetting-on-dielectric (EWOD) system for studying the bubble behavior. Both detachment and non-detachment processes of a small single bubble in a thick liquid film under EWOD were experimentally observed. The measurement of contact angle changes of the small air bubble shows relatively good agreement with Young-Lippmann's equation within the majority of the test voltage range, except for the saturation region. Meanwhile, we have experimentally demonstrated both the characteristics of single- and double-bubble detachment within a thin liquid film. Direct bubble detachment may occur when it touches the gas-liquid interface during the process of contact angle change, while indirect bubble detachment is highly possible due to the dramatic oscillation resulting from the detachment of adjacent bubbles. The experimental results demonstrate that EWOD can effectively facilitate the detachment of small air bubble in a thin liquid film.
16. A model of extravascular bubble evolution: effect of changes in breathing gas composition.
PubMed
Himm, J F; Homer, L D
1999-10-01
Observations of bubble evolution in rats after decompression from air dives (O. Hyldegaard and J. Madsen. Undersea Biomed. Res. 16: 185-193, 1989; O. Hyldegaard and J. Madsen. Undersea Hyperbaric Med. 21: 413-424, 1994; O. Hyldegaard, M. Moller, and J. Madsen. Undersea Biomed. Res. 18: 361-371, 1991) suggest that bubbles may resolve more safely when the breathing gas is a heliox mixture than when it is pure O(2). This is due to a transient period of bubble growth seen during switches to O(2) breathing. In an attempt to understand these experimental results, we have developed a multigas-multipressure mathematical model of bubble evolution, which consists of a bubble in a well-stirred liquid. The liquid exchanges gas with the bubble via diffusion, and the exchange between liquid and blood is described by a single-exponential time constant for each inert gas. The model indicates that bubbles resolve most rapidly in spinal tissue, in adipose tissue, and in aqueous tissues when the breathing gas is switched to O(2) after surfacing. In addition, the model suggests that switching to heliox breathing may prolong the existence of the bubble relative to breathing air for bubbles in spinal and adipose tissues. Some possible explanations for the discrepancy between model and experiment are discussed. PMID:10517787
17. Force Balance Model for Bubble Rise, Impact, and Bounce from Solid Surfaces.
PubMed
Manica, Rogerio; Klaseboer, Evert; Chan, Derek Y C
2015-06-23
A force balance model for the rise and impact of air bubbles in a liquid against rigid horizontal surfaces that takes into account effects of buoyancy and hydrodynamic drag forces, bubble deformation, inertia of the fluid via an added mass force, and a film force between the bubble and the rigid surface is proposed. Numerical solution of the governing equations for the position and velocity of the center of mass of the bubbles is compared against experimental data taken with ultraclean water. The boundary condition at the air-water interface is taken to be stress free, which is consistent for bubbles in clean water systems. Features that are compared include bubble terminal velocity, bubbles accelerating from rest to terminal speed, and bubbles impacting and bouncing off different solid surfaces for bubbles that have already or are yet to attain terminal speed. Excellent agreement between theory and experiments indicates that the forces included in the model constitute the main physical ingredients to describe the bouncing phenomenon. PMID:26035016
18. CFD modelling of most probable bubble nucleation rate from binary mixture with estimation of components' mole fraction in critical cluster
Hong, Ban Zhen; Keong, Lau Kok; Shariff, Azmi Mohd
2016-05-01
The employment of different mathematical models to address specifically for the bubble nucleation rates of water vapour and dissolved air molecules is essential as the physics for them to form bubble nuclei is different. The available methods to calculate bubble nucleation rate in binary mixture such as density functional theory are complicated to be coupled along with computational fluid dynamics (CFD) approach. In addition, effect of dissolved gas concentration was neglected in most study for the prediction of bubble nucleation rates. The most probable bubble nucleation rate for the water vapour and dissolved air mixture in a 2D quasi-stable flow across a cavitating nozzle in current work was estimated via the statistical mean of all possible bubble nucleation rates of the mixture (different mole fractions of water vapour and dissolved air) and the corresponding number of molecules in critical cluster. Theoretically, the bubble nucleation rate is greatly dependent on components' mole fraction in a critical cluster. Hence, the dissolved gas concentration effect was included in current work. Besides, the possible bubble nucleation rates were predicted based on the calculated number of molecules required to form a critical cluster. The estimation of components' mole fraction in critical cluster for water vapour and dissolved air mixture was obtained by coupling the enhanced classical nucleation theory and CFD approach. In addition, the distribution of bubble nuclei of water vapour and dissolved air mixture could be predicted via the utilisation of population balance model.
19. Localized removal of layers of metal, polymer, or biomaterial by ultrasound cavitation bubbles
PubMed Central
Fernandez Rivas, David; Verhaagen, Bram; Seddon, James R. T.; Zijlstra, Aaldert G.; Jiang, Lei-Meng; van der Sluis, Luc W. M.; Versluis, Michel; Lohse, Detlef; Gardeniers, Han J. G. E.
2012-01-01
We present an ultrasonic device with the ability to locally remove deposited layers from a glass slide in a controlled and rapid manner. The cleaning takes place as the result of cavitating bubbles near the deposited layers and not due to acoustic streaming. The bubbles are ejected from air-filled cavities micromachined in a silicon surface, which, when vibrated ultrasonically at a frequency of 200 kHz, generate a stream of bubbles that travel to the layer deposited on an opposing glass slide. Depending on the pressure amplitude, the bubble clouds ejected from the micropits attain different shapes as a result of complex bubble interaction forces, leading to distinct shapes of the cleaned areas. We have determined the removal rates for several inorganic and organic materials and obtained an improved efficiency in cleaning when compared to conventional cleaning equipment. We also provide values of the force the bubbles are able to exert on an atomic force microscope tip. PMID:23964308
20. Bubble production using a Non-Newtonian fluid in microfluidic flow focusing device
Wang, Yi-Lin; Ward, Thomas; Grant, Christine
2012-02-01
We experimentally study the production of micrometer-sized bubbles using microfluidic technology and a flow-focusing geometry. Bubbles are produced by using a mixture containing aqueous polyacrylamide of concentrations ranging from 0.01-0.10% by weight and several solution also containing a sodium-lauryl-sulfate (SLS) surfactant at concentrations ranging 0.01-0.1% by weight. The fluids are driven by controlling the static pressure above a hydrostatic head of the liquid while the disperse phase fluid static pressure is held constant (air). In the absence of surfactant the bubble production is discontinuous. The addition of surfactant stabilizes the bubble production. In each type of experiment, the bubble length l, velocity U and production frequency φ are measured and compared as a function of the inlet pressure ratio. The bubbles exhibit a contraction in their downstream length as a function of the polymer concentration which is investigated.
1. Bubble Formation at a Submerged Orifice for Aluminum Foams Produced by Gas Injection Method
Fan, Xueliu; Chen, Xiang; Liu, Xingnan; Zhang, Huiming; Li, Yanxiang
2013-02-01
The bubble formation at a submerged orifice in the process of aluminum foams produced by gas injection method is investigated. The experimental results show that the increase of the gas flow rate and the orifice diameter can lead to increasing of the bubble size. The large orifice can make the frequency of bubble formation decrease by slowing down the increase of the gas chamber pressure when the gas flow rate increases. The effect of the gas chamber volume on the bubble size can be ignored in the experiment when it expands from 1 to 125 cm3. A theoretical model of bubble formation, expansion, and detachment under constant flow conditions is established to predict the bubble size. The theoretical predictions for air-aluminum melt systems are consistent with the experimental results.
2. Bubble levitation and translation under single-bubble sonoluminescence conditions.
PubMed
Matula, Thomas J
2003-08-01
Bubble levitation in an acoustic standing wave is re-examined for conditions relevant to single-bubble sonoluminescence. Unlike a previous examination [Matula et al., J. Acoust. Soc. Am. 102, 1522-1527 (1997)], the stable parameter space [Pa,R0] is accounted for in this realization. Forces such as the added mass force and drag are included, and the results are compared with a simple force balance that equates the Bjerknes force to the buoyancy force. Under normal sonoluminescence conditions, the comparison is quite favorable. A more complete accounting of the forces shows that a stably levitated bubble does undergo periodic translational motion. The asymmetries associated with translational motion are hypothesized to generate instabilities in the spherical shape of the bubble. A reduction in gravity results in reduced translational motion. It is hypothesized that such conditions may lead to increased light output from sonoluminescing bubbles. PMID:12942960
3. Shear stress induced by a gas bubble pulsating in an ultrasonic field near a wall.
PubMed
Krasovitski, Boris; Kimmel, Eitan
2004-08-01
Some of the effects that therapeutic ultrasound has in medicine and biology may be associated with steady oscillations of gas bubbles in liquid, very close to tissue surface. The bubble oscillations induce on the surface steady shear stress attributed to microstreaming. A mathematical simulation of the problem for both free and capsulated bubbles, known as contrast agents, is presented here. The simulation is based on a solution of Laplace's equation for potential flow and existing models for microstreaming. The solution for potential flow was obtained numerically using a boundary integral method. The solution provides the evolution of the bubble shape, the distribution of the velocity potential on the surface, and the shear stress along the surface. The simulation shows that significant shear stresses develop on the surface when the bubble bounces near the tissue surface. In this case, pressure amplitude of 20 kPa generates maximal steady shear stress of several kilo Pascal. Substantial shear stress on the tissue surface takes place inside a circular zone with a radius about half of the bubble radius. The predicted shear stress is greater than stress that causes hemolysis in blood and several orders of magnitude greater than the physiological stress induced on the vessel wall by the flowing blood. PMID:15344403
4. Thermocapillary Migration and Interactions of Bubbles and Drops
NASA Technical Reports Server (NTRS)
Subramaniam, R. Shankar; Balasubramaniam, R.; Wozniak, G.; Hadland, P. H.
1999-01-01
Experiments were performed aboard the LMS mission of the Space Shuttle in summer 1996 in the BDPU on isolated air bubbles and Fluorinert FC-75 drops as well as on interacting bubbles/drops migrating in a temperature gradient in a Dow-Corning DC-200 series silicone oil of nominal viscosity 10 centistokes. The data, recorded in the form of videotape images as well as cine images in selected runs, have been analyzed. The behavior of the isolated objects is consistent with earlier observations made aboard the IML-2 mission while the range of Reynolds and Marangoni numbers has been extended substantially over that in the IML-2 experiments. Large bubbles were found to be slightly deformed to an oblate shape while no deformation could be detected in the case of similarly large drops. Results on interacting drops and bubbles display interesting and unanticipated features. In some experiments, drops are found to follow a three-dimensional trajectory. In others, trailing drops and bubbles are found to move off the axis of the cell when migrating behind a leading drop or bubble which moves along the axis. In this type of run, if the trailing drop is sufficiently large, it is found to pass the leading drop. Finally, behavior similar to that observed in IML-2, namely that a small leading drop slows the movement of a larger trailing drop moving along the cell axis, was observed as well.
5. Simulation of bubble growth and coalescence in reacting polymer foams
Marchisio, Daniele; Karimi, Mohsen
2015-11-01
This work concerns with the simulation of reacting polymer foams with computational fluid dynamics (CFD). In these systems upon mixing of different ingredients polymerization starts and some gaseous compounds are produced, resulting in the formation of bubbles that growth and coalesce. As the foam expands, the polymerization proceeds resulting in an increase of the apparent viscosity. The evolution of the collective behavior of the bubbles within the polymer foam is tracked by solving a master kinetic equation, formulated in terms of the bubble size distribution. The rate with which individual bubbles grow is instead calculated by resolving the momentum and concentration boundary layers around the bubbles. Moreover, since it is useful to track the evolution of the interface between the foam and the surrounding air, a volume-of-fluid (VOF) model is adopted. The final computational model is implemented in the open-source CFD code openFOAM by making use of the compressibleInterFoam solver. The master kinetic equation is solved with a quadrature-based moment method (QBMM) directly implemented in openFOAM, whereas the bubble growth model is solved independently and ''called'' from the CFD code by using an unstructured database. Model predictions are validated against experimental data. This work was funded by the European Commission under the grant agreement number 604271 (Project acronym: MoDeNa; call identifier: FP7-NMP-2013-SMALL-7).
6. The effect of nearby bubbles on array gain.
PubMed
Culver, R Lee; Park, J Daniel; Leighton, Timothy G; Coles, David G H
2011-12-01
The coherent processing of signals from multiple hydrophones in an array offers improvements in angular resolution and signal-to-noise ratio. When the array is steered in a particular direction, the signals arriving from that direction are added in phase, and any signals arriving from other directions are not. Array gain (AG) is a measure of how much the signal arriving from the steering direction is amplified relative to signals arriving from all other directions. The subject of this paper is the manner in which the AG of an acoustic array operating in water that contains air bubbles is affected by scattering from nearby bubbles. The effects of bubbles on acoustic attenuation and dispersion are considered separately from their effects on AG. Acoustic measurements made in bubbly water using the AB Wood tank at the Institute of Sound and Vibration Research, University of Southampton, in June 2008 show that as bubble density increases, relative phase shifts in individual hydrophone signals increase and signal correlation among the hydrophones is reduced. A theory and numerical simulation linking bubble density at the hydrophone to the AG is in good agreement with the measurements up to the point where multiple scattering becomes important. PMID:22225039
7. Endothelial dysfunction correlates with decompression bubbles in rats.
PubMed
Zhang, Kun; Wang, Dong; Jiang, Zhongxin; Ning, Xiaowei; Buzzacott, Peter; Xu, Weigang
2016-01-01
Previous studies have documented that decompression led to endothelial dysfunction with controversial results. This study aimed to clarify the relationship between endothelial dysfunction, bubble formation and decompression rate. Rats were subjected to simulated air dives with one of four decompression rates: one slow and three rapid. Bubble formation was detected ultrasonically following decompression for two hours, before measurement of endothelial related indices. Bubbles were found in only rapid-decompressed rats and the amount correlated with decompression rate with significant variability. Serum levels of ET-1, 6-keto-PGF1α, ICAM-1, VCAM-1 and MDA, lung Wet/Dry weight ratio and histological score increased, serum NO decreased following rapid decompression. Endothelial-dependent vasodilatation to Ach was reduced in pulmonary artery rings among rapid-decompressed rats. Near all the above changes correlated significantly with bubble amounts. The results suggest that bubbles may be the causative agent of decompression-induced endothelial damage and bubble amount is of clinical significance in assessing decompression stress. Furthermore, serum levels of ET-1 and MDA may serve as sensitive biomarkers with the capacity to indicate endothelial dysfunction and decompression stress following dives. PMID:27615160
8. Particle image velocimetry studies of bubble growth and detachment by high-speed photography
Stickland, Mathew; Dempster, William; Lothian, Lee; Oldroyd, Andrew
1997-05-01
An understanding of bubble flows is important in the design of process equipment, particularly in the chemical and power industries. In vapor-liquid processes the mass and heat transfer between the phases is dominated by the liquid-vapor interface and is determined by the number, size, and shape of the bubbles. For bubble flows these characteristics are often controlled by the generation mechanisms and, since bubble flows are often generated at an orifice, it is important to determine the controlling parameters which dictate how bubbles grow and detach. For bubbles growing at orifices the liquid displacement is an important feature and affects the pressure distribution acting on the bubble and the heat and mass transfer that may occur at the bubble interface. Therefore, in this study, the characteristics of the liquid velocity field are studied experimentally using Particle image Velocimetry (PIV) during growth, detachment and translation of a bubble being generated at an orifice supplied with a constant mass flow rate of air. The process is transient and occurs over a period of approximately 50 msecs. In order to map the transient flow field a combination of high speed cine and cross correlation PIV image processing has been used to determine the liquid velocity vector field during the bubble growth process. The paper contains details of the PIV technique and presents several of the velocity vector maps calculated.
9. The Measurement and Parameterization of Effective Radius of Droplets in Warm Stratocumulus Clouds.
Martin, G. M.; Johnson, D. W.; Spice, A.
1994-07-01
Observations from the Meteorological Research Flight's Hercules C-130 aircraft of the microphysical characteristics of warm stratocumulus clouds have been analyzed to investigate the variation of the effective radius of cloud droplets in layer clouds. Results from experiments in the eastern Pacific, South Atlantic, subtropical regions of the North Atlantic, and the sea areas around the British Isles are presented. In situations where entrainment effects are small the (effective radius)3 is found to be a linear function of the (volume-averaged radius)3 in a given cloud and can thus be parameterized with respect to the liquid water content and the droplet number concentration in the cloud. However, the shape of the droplet size spectrum is very dependent on the cloud condensation nuclei (CCN) characteristics below cloud base, and the relationship between effective radius and volume-averaged radius varies between maritime air masses and continental air masses. This study also details comparisons that have been made in stratocumulus between the droplet number concentrations and (a) aerosol concentrations below cloud base in the size range 0.1 to 3.0 m and (b) CCN supersaturation spectra in the boundary layer. A parameterization relating droplet concentration and aerosol concentration is suggested. The effects of nonadiabatic processes on the parameterization of effective radius are discussed. Drizzle is found to have little effect near cloud top, but in precipitating stratocumulus clouds the parameterization breaks down near cloud base. Comparisons are made between this parameterization of effective radius and others used currently or in the past.
10. Bubbles, Bubbles, Tremors & Trouble: The Bayou Corne Sinkhole
Nunn, J. A.
2013-12-01
In May 2012, thermogenic methane bubbles were first observed in Bayou Corne in Assumption Parish, Louisiana. As of July 2013, ninety one bubbling sites have been identified. Gas was also found in the top of the Mississippi River Alluvial Aquifer (MRAA) about 125 ft below the surface. Vent wells drilled into the MRAA have flared more 16 million SCF of gas. Trace amounts of hydrogen sulfide also have been detected. Bayou Corne flows above the Napoleonville salt dome which has been an active area for oil and gas exploration since the 1920s. The dome is also a site of dissolution salt mining which has produced large caverns with diameters of up to 300 ft and heights of 2000 ft. Some caverns are used for storage of natural gas. Microseismic activity was confirmed by an Earthscope seismic station in White Castle, LA in July 2012. An array of microseismic stations set up in the area recorded more than 60 microseismic events in late July and early August, 2012. These microseismic events were located on the western side of the dome. Estimated focal depths are just above the top of salt. In August 2012, a sinkhole developed overnight just to the northwest of a plugged and abandoned brine filled cavern (see figure below). The sinkhole continues to grow in area to more than 20 acres and has consumed a pipeline right of way. The sinkhole is more than 750 ft deep at its center. Microseismic activity was reduced for several months following the formation of the sinkhole. Microseismic events have reoccurred episodically since then with periods of frequent events preceding slumping of material into the sinkhole or a 'burp' where fluid levels in the sinkhole drop and then rebound followed by a decrease in microseismic activity. Some gas and/or oil may appear at the surface of the sinkhole following a 'burp'. Very long period events also have been observed which are believed to be related to subsurface fluid movement. A relief well drilled into the abandoned brine cavern found that
11. Stable tridimensional bubble clusters in multi-bubble sonoluminescence (MBSL).
PubMed
Rosselló, J M; Dellavale, D; Bonetto, F J
2015-01-01
In the present work, stable clusters made of multiple sonoluminescent bubbles are experimentally and theoretically studied. Argon bubbles were acoustically generated and trapped using bi-frequency driving within a cylindrical chamber filled with a sulfuric acid aqueous solution (SA85w/w). The intensity of the acoustic pressure field was strong enough to sustain, during several minutes, a large number of positionally and spatially fixed (without pseudo-orbits) sonoluminescent bubbles over an ellipsoidally-shaped tridimensional array. The dimensions of the ellipsoids were studied as a function of the amplitude of the applied low-frequency acoustic pressure (PAc(LF)) and the static pressure in the fluid (P0). In order to explain the size and shape of the bubble clusters, we performed a series of numerical simulations of the hydrodynamic forces acting over the bubbles. In both cases the observed experimental behavior was in excellent agreement with the numerical results. The simulations revealed that the positionally stable region, mainly determined by the null primary Bjerknes force (F→Bj), is defined as the outer perimeter of an axisymmetric ellipsoidal cluster centered in the acoustic field antinode. The role of the high-frequency component of the pressure field and the influence of the secondary Bjerknes force are discussed. We also investigate the effect of a change in the concentration of dissolved gas on the positional and spatial instabilities through the cluster dimensions. The experimental and numerical results presented in this paper are potentially useful for further understanding and modeling numerous current research topics regarding multi-bubble phenomena, e.g. forces acting on the bubbles in multi-frequency acoustic fields, transient acoustic cavitation, bubble interactions, structure formation processes, atomic and molecular emissions of equal bubbles and nonlinear or unsteady acoustic pressure fields in bubbly media. PMID:24974006
12. Bubbles trapped in a fluidized bed: Trajectories and contact area
Poryles, Raphaël; Vidal, Valérie; Varas, Germán
2016-03-01
This work investigates the dynamics of bubbles in a confined, immersed granular layer submitted to an ascending gas flow. In the stationary regime, a central fluidized zone of parabolic shape is observed, and the bubbles follow different dynamics: either the bubbles are initially formed outside the fluidized zone and do not exhibit any significant motion over the experimental time or they are located inside the fluidized bed, where they are entrained downwards and are, finally, captured by the central air channel. The dependence of the air volume trapped inside the fluidized zone, the bubble size, and the three-phase contact area on the gas injection flow rate and grain diameter are quantified. We find that the volume fraction of air trapped inside the fluidized region is roughly constant and of the order of 2%-3% when the gas flow rate and the grain size are varied. Contrary to intuition, the gas-liquid-solid contact area, normalized by the air injected into the system, decreases when the flow rate is increased, which may have significant importance in industrial applications.
13. a Comprehensive Model for Capillary Pressure Difference across a Drop/bubble Flowing Through a Constricted Capillary
Liang, Mingchao; Wei, Junhong; Han, Hongmei; Fu, Chengguo; Liu, Jianjun
2015-09-01
The capillary pressure is one of the crucial parameters in many science and engineering applications such as composite materials, interface science, chemical engineering, oil exploration, etc. The drop/bubble formation and its mechanisms that affect the permeability of porous media have steadily attracted much attention in the past. When a drop/bubble moves from a larger capillary to a smaller one, it is often obstructed by an additional pressure difference caused by the capillary force. In this paper, a comprehensive model is derived for the capillary pressure difference when a drop/bubble flows through a constricted capillary, i.e. a geometrically constricted passage with an abrupt change in radius. The proposed model is expressed as a function of the smaller capillary radius, pore-throat ratio, contact angle, surface tension and length of the drop/bubble in the smaller capillary. The model predictions are compared with the available experimental data, and good agreement is found between them.
14. Bubble formation in microgravity
NASA Technical Reports Server (NTRS)
Antar, Basil N.
1994-01-01
Two KC-135 flight campaigns have been conducted to date which are specifically dedicated to study bubble formation in microgravity. The first flight was conducted during March 14-18, 1994, and the other during June 20-24, 1994. The results from the June 1994 flight have not been analyzed yet, while the results from the March flight have been partially analyzed. In the first flight three different experiments were performed, one with the specific aim at determining whether or not cavitation can take place during any of the fluid handling procedures adopted in the shuttle bioprocessing experiments. The other experiments were concerned with duplicating some of the procedures that resulted in bubble formation, namely the NCS filling procedure and the needle scratch of a solid surface. The results from this set of experiments suggest that cavitation did not take place during any of the fluid handling procedures. The results clearly indicate that almost all were generated as a result of the breakup of the gas/liquid interface. This was convincingly demonstrated in the scratch tests as well as in the liquid fill tests.
15. Bubble formation in microgravity
NASA Technical Reports Server (NTRS)
Antar, Basil N.
1996-01-01
An extensive experimental program was initiated for the purpose of understanding the mechanisms leading to bubble generation during fluid handling procedures in a microgravity environment. Several key fluid handling procedures typical for PCG experiments were identified for analysis in that program. Experiments were designed to specifically understand how such procedures can lead to bubble formation. The experiments were then conducted aboard the NASA KC-135 aircraft which is capable of simulating a low gravity environment by executing a parabolic flight attitude. However, such a flight attitude can only provide a low gravity environment of approximately 10-2go for a maximum period of 30 seconds. Thus all of the tests conducted for these experiments were designed to last no longer than 20 seconds. Several experiments were designed to simulate some of the more relevant fluid handling procedures during protein crystal growth experiments. These include submerged liquid jet cavitation, filling of a cubical vessel, submerged surface scratch, attached drop growth, liquid jet impingement, and geysering experiments. To date, four separate KC-135 flight campaigns were undertaken specifically for performing these experiments. However, different experiments were performed on different flights.
16. Controlled permeation of cell membrane by single bubble acoustic cavitation.
PubMed
Zhou, Y; Yang, K; Cui, J; Ye, J Y; Deng, C X
2012-01-10
radius of the pores was estimated from the measured TMC to be 0.106±0.032μm (n=70) for acoustic pressure of 1.5MPa (duration 13.3μs), and increased to 0.171±0.030μm (n=125) for acoustic pressure of 1.7MPa and to 0.182±0.052μm (n=112) for a pulse duration of 40μs (1.5MPa). These results from controlled cell membrane permeation by cavitation of single bubbles revealed insights and key factors affecting sonoporation at the single cell level. PMID:21945682
17. Mechanotransductional Basis of Endothelial Cell Response to Intravascular Bubbles
PubMed Central
Klinger, Alexandra L.; Pichette, Benjamin; Sobolewski, Peter; Eckmann, David M.
2011-01-01
Vascular air embolism resulting from too rapid decompression is a well-known risk in deep-sea diving, aviation and space travel. It is also a common complication during surgery or other medical procedures when air or other endogenously administered gas is entrained in the circulation. Preventive and post-event treatment options are extremely limited for this dangerous condition, and none of them address the poorly understood pathophysiology of endothelial response to intravascular bubble presence. Using a novel apparatus allowing precise manipulation of microbubbles in real time fluorescence microscopy studies, we directly measure human umbilical vein endothelial cell responses to bubble contact. Strong intracellular calcium transients requiring extracellular calcium are observed upon cell-bubble interaction. The transient is eliminated both by the presence of the stretch activated channel inhibitor, gadolinium, and the transient receptor potential vanilliod family inhibitor, ruthenium red. No bubble induced calcium upsurge occurs if the cells are pretreated with an inhibitor of actin polymerization, cytochalasin-D. This study explores the biomechanical mechanisms at play in bubble interfacial interactions with endothelial surface layer (ESL) macromolecules, reassessing cell response after selective digestion of glycocalyx glycosoaminoglycans, hyaluran (HA) and heparin sulfate (HS). HA digestion causes reduction of cell-bubble adherence and a more rapid induction of calcium influx after contact. HS depletion significantly decreases calcium transient amplitudes, as does pharmacologically induced sydencan ectodomain shedding. The surfactant perfluorocarbon oxycyte abolishes any bubble induced calcium transient, presumably through direct competition with ESL macromolecules for interfacial occupancy, thus attenuating the interactions that trigger potentially deleterious biochemical pathways. PMID:21931900
18. Bubble masks for time-encoded imaging of fast neutrons.
SciTech Connect
Brubaker, Erik; Brennan, James S.; Marleau, Peter; Nowack, Aaron B.; Steele, John; Sweany, Melinda; Throckmorton, Daniel J.
2013-09-01
Time-encoded imaging is an approach to directional radiation detection that is being developed at SNL with a focus on fast neutron directional detection. In this technique, a time modulation of a detected neutron signal is induced-typically, a moving mask that attenuates neutrons with a time structure that depends on the source position. An important challenge in time-encoded imaging is to develop high-resolution two-dimensional imaging capabilities; building a mechanically moving high-resolution mask presents challenges both theoretical and technical. We have investigated an alternative to mechanical masks that replaces the solid mask with a liquid such as mineral oil. Instead of fixed blocks of solid material that move in pre-defined patterns, the oil is contained in tubing structures, and carefully introduced air gaps-bubbles-propagate through the tubing, generating moving patterns of oil mask elements and air apertures. Compared to current moving-mask techniques, the bubble mask is simple, since mechanical motion is replaced by gravity-driven bubble propagation; it is flexible, since arbitrary bubble patterns can be generated by a software-controlled valve actuator; and it is potentially high performance, since the tubing and bubble size can be tuned for high-resolution imaging requirements. We have built and tested various single-tube mask elements, and will present results on bubble introduction and propagation as a function of tubing size and cross-sectional shape; real-time bubble position tracking; neutron source imaging tests; and reconstruction techniques demonstrated on simple test data as well as a simulated full detector system.
19. Acoustic Behavior of Vapor Bubbles
NASA Technical Reports Server (NTRS)
Prosperetti, Andrea; Oguz, Hasan N.
1996-01-01
In a microgravity environment vapor bubbles generated at a boiling surface tend to remain near it for a long time. This affects the boiling heat transfer and in particular promotes an early transition to the highly inefficient film boiling regime. This paper describes the physical basis underlying attempts to remove the bubbles by means of pressure radiation forces.
20. Optical behavior of surface bubbles
Straulino, Samuele; Gambi, Cecilia M. C.; Molesini, Giuseppe
2015-11-01
The observation of diamond-like light spots produced by surface bubbles obliquely illuminated is reported. The phenomenon is discussed in terms of geometrical optics, and an explanation is provided attributing the effect to the astigmatism introduced by the deformation of the liquid surface surrounding the bubble. An essential ray tracing program is outlined and used to reconstruct the observed phenomenon numerically.
1. Vortex-ring-induced large bubble entrainment during drop impact.
PubMed
Thoraval, Marie-Jean; Li, Yangfan; Thoroddsen, Sigurdur T
2016-03-01
For a limited set of impact conditions, a drop impacting onto a pool can entrap an air bubble as large as its own size. The subsequent rise and rupture of this large bubble plays an important role in aerosol formation and gas transport at the air-sea interface. The large bubble is formed when the impact crater closes up near the pool surface and is known to occur only for drops that are prolate at impact. Herein we use experiments and numerical simulations to show that a concentrated vortex ring, produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self-destruct. Rather, it is somewhat weaker vortices that can deform the deeper craters, which manage to pinch off the large bubbles. These observations also explain why the strongest and most penetrating vortex rings emerging from drop impacts are not produced by oblate drops but by more prolate drop shapes, as had been observed in previous experiments. PMID:27078468
2. Vortex-ring-induced large bubble entrainment during drop impact
Thoraval, Marie-Jean; Li, Yangfan; Thoroddsen, Sigurdur T.
2016-03-01
For a limited set of impact conditions, a drop impacting onto a pool can entrap an air bubble as large as its own size. The subsequent rise and rupture of this large bubble plays an important role in aerosol formation and gas transport at the air-sea interface. The large bubble is formed when the impact crater closes up near the pool surface and is known to occur only for drops that are prolate at impact. Herein we use experiments and numerical simulations to show that a concentrated vortex ring, produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self-destruct. Rather, it is somewhat weaker vortices that can deform the deeper craters, which manage to pinch off the large bubbles. These observations also explain why the strongest and most penetrating vortex rings emerging from drop impacts are not produced by oblate drops but by more prolate drop shapes, as had been observed in previous experiments.
3. Bubble dynamics in a variable gap Hele-Shaw cell
Piedra, Saul; Domiguez, Roberto; Ramos, Eduardo
2015-11-01
We present observations of the dynamics of individual air bubbles ascending in a Hele-Shaw cell filled with water. Cells with gaps of 1 mm, 1.5 and 2.5 mm are used and the volume of the bubbles is such that we observe bubbles with apparent diameter from 2 mm to 7.3 mm. Given that we work with air and water in all experiments, the Morton number is constant and equal to 2 . 5 ×10-11 . The results are given in terms of the Eotvos, Archimedes and Reynolds numbers, and the trajectories and wakes of the bubbles are described as functions of the gap. In all cases we observe a linear relationship between the Reynolds and Archimedes numbers, but the proportionality constant varies with the gap. Also, although the wake is composed of alternating vortices similar to the von Karman vortex street, the size and location of the vortices vary with the gap. The analysis of some features of the observations and the description of the shape of the bubbles and dominant forces are made with a two dimensional numerical solution of the conservation equations using a front tracking strategy.
4. A monolithic mass tracking formulation for bubbles in incompressible flow
SciTech Connect
Aanjaneya, Mridul Patkar, Saket Fedkiw, Ronald
2013-08-15
We devise a novel method for treating bubbles in incompressible flow that relies on the conservative advection of bubble mass and an associated equation of state in order to determine pressure boundary conditions inside each bubble. We show that executing this algorithm in a traditional manner leads to stability issues similar to those seen for partitioned methods for solid–fluid coupling. Therefore, we reformulate the problem monolithically. This is accomplished by first proposing a new fully monolithic approach to coupling incompressible flow to fully nonlinear compressible flow including the effects of shocks and rarefactions, and then subsequently making a number of simplifying assumptions on the air flow removing not only the nonlinearities but also the spatial variations of both the density and the pressure. The resulting algorithm is quite robust, has been shown to converge to known solutions for test problems, and has been shown to be quite effective on more realistic problems including those with multiple bubbles, merging and pinching, etc. Notably, this approach departs from a standard two-phase incompressible flow model where the air flow preserves its volume despite potentially large forces and pressure differentials in the surrounding incompressible fluid that should change its volume. Our bubbles readily change volume according to an isothermal equation of state.
5. Mass and radius of cosmic balloons
NASA Technical Reports Server (NTRS)
Wang, Yun
1994-01-01
Cosmic balloons are spherical domain walls with relativistic particles trapped inside. We derive the exact mass and radius relations for a static cosmic balloon using Gauss-Codazzi equations. The cosmic balloon mass as a function of its radius, M(R), is found to have a functional form similar to that of fermion soliton stars, with a fixed point at 2GM(R)/R approximately or equal to 0.486 which corresponds to the limit of infinite central density. We derive a simple analytical approximation for the mass density of a spherically symmetric relativistic gas star. When applied to the computation of the mass and radius of a cosmic balloon, the analytical approximation yields fairly good agreement with the exact numerical solutions.
6. A Maximum Radius for Habitable Planets.
PubMed
Alibert, Yann
2015-09-01
We compute the maximum radius a planet can have in order to fulfill two constraints that are likely necessary conditions for habitability: 1- surface temperature and pressure compatible with the existence of liquid water, and 2- no ice layer at the bottom of a putative global ocean, that would prevent the operation of the geologic carbon cycle to operate. We demonstrate that, above a given radius, these two constraints cannot be met: in the Super-Earth mass range (1-12 Mearth), the overall maximum that a planet can have varies between 1.8 and 2.3 Rearth. This radius is reduced when considering planets with higher Fe/Si ratios, and taking into account irradiation effects on the structure of the gas envelope. PMID:26159097
7. Evolution of a gas bubble in porous matrix filled by methane hydrate
Tsiberkin, Kirill; Lyubimov, Dmitry; Lyubimova, Tatyana; Zikanov, Oleg
2013-04-01
Behavior of a small isolated hydrate-free inclusion (a bubble) within hydrate-bearing porous matrix is studied analytically and numerically. An infinite porous matrix of uniform properties with pores filled by methane hydrates and either water (excessive water situation) or methane gas (excessive gas situation) is considered. A small spherical hydrate-free bubble of radius R0 exists at initial moment within the matrix due to overheating relative to the surrounding medium. There is no continuing heat supply within the bubble, so new hydrate forms on its boundary, and its radius decreases with time. The process is analysed in the framework of the model that takes into account the phase transition and accompanying heat and mass transport processes and assumes spherical symmetry. It is shown that in the case of small (~ 10-2-10-1 m) bubbles, convective fluxes are negligible and the process is fully described by heat conduction and phase change equations. A spherically symmetric Stefan problem for purely conduction-controlled evolution is solved analytically for the case of equilibrium initial temperature and pressure within the bubble. The self-similar solution is verified, with good results, in numerical simulations based on the full filtration and heat transfer model and using the isotherm migration method. Numerical simulations are also conducted for a wide range of cases not amenable to analytical solution. It is found that, except for initial development of an overheated bubble, its radius evolves with time following the self-similar formula: R(t) ( t)1-2 R0-= 1 - tm- , (1) where tm is the life-time of bubble (time of its complete freezing). The analytical solution shows that tm follows 2 tm ~ (R0-?) , (2) where ? is a constant determined by the temperature difference ΔT between the bubble's interior and far field. We consider implications for natural hydrate deposits. As an example, for a bubble with R0 = 4 cm and ΔT = 0.001 K, we find tm ~ 5.7 ? 106 s (2
8. Gas permeation of LC films observed by smectic bubble expansion.
PubMed
Ishii, Y; Tabe, Y
2009-11-01
Gas permeation through liquid crystal (LC) films was examined using hemispherical smectic bubbles. A smectic bubble, when the inside and the outside are filled with different gases, should expand or shrink toward the quasi-equilibrium state, where the influx and efflux caused by osmotic pressure are balanced. Deriving a simple formula that directly converts the quasi-equilibrated bubble radius to the gas permeation, we determined the absolute permeability coefficients of 8 simple gases through the smectic bubble. The permeability was distributed in such a wide range that carbon-dioxide had more than 20 times larger value than nitrogen, the dependence of which on the gas species was mostly dominated by their solubility into the LCs. Dividing the measured permeability by the calculated solubility, we obtained the diffusion constants as well, yet whose magnitude and the dependence on the solute size could not be explained by either conventional continuum theories or microscopic diffusion models. In order to describe the diffusion of small solutes in the liquid solvent composed of large molecules, a new theoretical framework may be necessary. PMID:19816725
9. Bubble formation during horizontal gas injection into downward-flowing liquid
Bai, Hua; Thomas, Brian G.
2001-12-01
Bubble formation during gas injection into turbulent downward-flowing water is studied using high-speed videos and mathematical models. The bubble size is determined during the initial stages of injection and is very important to turbulent multiphase flow in molten-metal processes. The effects of liquid velocity, gas-injection flow rate, injection hole diameter, and gas composition on the initial bubble-formation behavior have been investigated. Specifically, the bubble-shape evolution, contact angles, size, size range, and formation mode are measured. The bubble size is found to increase with increasing gas-injection flow rate and decreasing liquid velocity and is relatively independent of the gas injection hole size and gas composition. Bubble formation occurs in one of four different modes, depending on the liquid velocity and gas flow rate. Uniform-sized spherical bubbles form and detach from the gas injection hole in mode I for a low liquid speed and small gas flow rate. Modes III and IV occur for high-velocity liquid flows, where the injected gas elongates down along the wall and breaks up into uneven-sized bubbles. An analytical two-stage model is developed to predict the average bubble size, based on realistic force balances, and shows good agreement with measurements. Preliminary results of numerical simulations of bubble formation using a volume-of-fluid (VOF) model qualitatively match experimental observations, but more work is needed to reach a quantitative match. The analytical model is then used to estimate the size of the argon bubbles expected in liquid steel in tundish nozzles for conditions typical of continuous casting with a slide gate. The average argon bubble sizes generated in liquid steel are predicted to be larger than air bubbles in water for the same flow conditions. However, the differences lessen with increasing liquid velocity.
10. Inside the Bondi radius of M87
Russell, H. R.; Fabian, A. C.; McNamara, B. R.; Broderick, A. E.
2015-07-01
Chandra X-ray observations of the nearby brightest cluster galaxy M87 resolve the hot gas structure across the Bondi accretion radius of the central supermassive black hole (SMBH), a measurement possible in only a handful of systems but complicated by the bright nucleus and jet emission. By stacking only short frame-time observations to limit pileup, and after subtracting the nuclear point spread function, we analysed the X-ray gas properties within the Bondi radius at 0.12-0.22 kpc (1.5-2.8 arcsec), depending on the black hole mass. Within 2 kpc radius, we detect two significant temperature components, which are consistent with constant values of 2 and 0.9 keV down to 0.15 kpc radius. No evidence was found for the expected temperature increase within ˜ 0.25 kpc due to the influence of the SMBH. Within the Bondi radius, the density profile is consistent with ρ ∝ r-1. The lack of a temperature increase inside the Bondi radius suggests that the hot gas structure is not dictated by the SMBH's potential and, together with the shallow density profile, shows that the classical Bondi rate may not reflect the accretion rate on to the SMBH. If this density profile extends in towards the SMBH, the mass accretion rate on to the SMBH could be at least two orders of magnitude less than the Bondi rate, which agrees with Faraday rotation measurements for M87. We discuss the evidence for outflow from the hot gas and the cold gas disc and for cold feedback, where gas cooling rapidly from the hot atmosphere could feed the cirumnuclear disc and fuel the SMBH. At 0.2 kpc radius, the cooler X-ray temperature component represents ˜20 per cent of the total X-ray gas mass and, by losing angular momentum to the hot gas component, could provide a fuel source of cold clouds within the Bondi radius.
11. Exposure of the forearm and distal radius.
PubMed
Klausmeyer, Melissa A; Mudgal, Chaitanya
2014-11-01
Approaches to the forearm use internervous planes to allow adequate bone exposure and prevent muscle denervation. The Henry approach utilizes the plane between muscles supplied by the median and radial nerves. The Thompson approach utilizes the plane between muscles supplied by the radial and posterior interosseous nerves. The distal radius may be approached volarly. The extended flexor carpi radialis approach is useful for intraarticular fractures, subacute fractures, and malunions. The distal radius can be approached dorsally by releasing the third dorsal compartment and continuing the dissection subperiosteally. Choice of approach depends on the injury pattern and the need for exposure. PMID:25440071
12. Distal radius fracture: diagnosis, treatment, and controversies.
PubMed
Tang, Jin Bo
2014-07-01
This article presents the diagnosis and treatment of distal radius fractures with emphasis on (1) current common principles, (2) the author's current practices, and (3) controversies. The author emphasizes that displaced distal radius fractures should be approached first with a trial of closed reduction, with or without percutaneous pinning. If this reduction is unstable or unsuccessful, open reduction is indicated. Early treatments include percutaneous pinning through the distal radioulnar joint, early or delayed reattachment/repair of the avulsed dorsal periphery of the triangular fibrocartilage complex (TFCC), reattachment of the TFCC to the ulna fovea, and late reconstruction. PMID:24996466
13. Influence of bubble size on micro-bubble drag reduction
Shen, Xiaochun; Ceccio, Steven L.; Perlin, Marc
2006-09-01
Micro-bubble drag reduction experiments were conducted in a turbulent water channel flow. Compressed nitrogen was used to force flow through a slot injector located in the plate beneath the boundary layer of the tunnel test section. Gas and bubbly mixtures were injected into a turbulent boundary layer (TBL), and the resulting friction drag was measured downstream of the injector. Injection into tap water, a surfactant solution (Triton X-100, 20 ppm), and a salt-water solution (35 ppt) yielded bubbles of average diameter 476, 322 and 254 μm, respectively. In addition, lipid stabilized gas bubbles (44 μm) were injected into the boundary layer. Thus, bubbles with d + values of 200 to 18 were injected. The results indicate that the measured drag reduction by micro-bubbles in a TBL is related strongly to the injected gas volumetric flow rate and the static pressure in the boundary layer, but is essentially independent of the size of the micro-bubbles over the size range tested.
14. Three dimensional calculations of the effective Kapitza resistance of UO2 grain boundaries containing intergranular bubbles
Millett, Paul C.; Tonks, Michael R.; Chockalingam, K.; Zhang, Yongfeng; Biner, S. B.
2013-08-01
A parametric study has been performed that quantifies the effective change in grain boundary Kapitza resistance due to the presence of intergranular bubbles. The steady-state heat conduction equation was solved in three-dimensional space using INL's MOOSE finite element software, with which spacial mesh adaptivity was used to resolve interfacial widths down to several nanometers while investigating bubble sizes up to a micrometer. Three critical parameters were systematically varied: the intergranular bubble radius, the fractional grain boundary bubble coverage, and the Kapitza resistance of the intact grain boundary. Using the simulation results, a mathematical model dependent on each of these parameters was developed to describe the effective Kapitza resistance. Furthermore, we illustrate how this model can be implemented in a fuel performance code to predict the temperature profile of a cylindrical fuel pellet.
15. Linear bubble plume model for hypolimnetic oxygenation: Full-scale validation and sensitivity analysis
Singleton, V. L.; Gantzer, P.; Little, J. C.
2007-02-01
An existing linear bubble plume model was improved, and data collected from a full-scale diffuser installed in Spring Hollow Reservoir, Virginia, were used to validate the model. The depth of maximum plume rise was simulated well for two of the three diffuser tests. Temperature predictions deviated from measured profiles near the maximum plume rise height, but predicted dissolved oxygen profiles compared very well with observations. A sensitivity analysis was performed. The gas flow rate had the greatest effect on predicted plume rise height and induced water flow rate, both of which were directly proportional to gas flow rate. Oxygen transfer within the hypolimnion was independent of all parameters except initial bubble radius and was inversely proportional for radii greater than approximately 1 mm. The results of this work suggest that plume dynamics and oxygen transfer can successfully be predicted for linear bubble plumes using the discrete-bubble approach.
16. Optical shielding of nickel nanoparticle by a bubble: Optical limiting gets limited
Shukla, Vijay; Jayabalan, J.; Chari, Rama
2016-06-01
We have demonstrated that in a nickel nanoparticle colloid, the optical limiting action reduces if a vapor bubble forms around the nanoparticle. The energy-dependent transmission and z-scan measurements on nickel nanoparticles in toluene show the onset of an additional process. At high fluence excitation, the particle becomes less visible to the later part of the incoming pulse due to the heat generated bubble formed around it. We have proposed a simple "particle-in-bubble" model which fits the optical limiting and z-scan curves quite well. Using this model, we have also estimated that the bubble radius increases at a rate of 4.5 m/s.
17. An acoustic levitation technique for the study of nonlinear oscillations of gas bubbles in liquids
Young, D. A.; Crum, L. A.
1983-08-01
A technique of acoustic levitation was developed for the study of individual gas bubbles in a liquid. Isopropyl alcohol and a mixture of glycerine and water (33-1/3% glycerine by volume) were the two liquids used in this research. Bubbles were levitated near the acoustic pressure antinode of an acoustic wave in the range of 20-22 kHz. Measurements were made of the levitation number as a function of the normalized radius of the bubbles. The levitation number is the ratio of the hydrostatic pressure gradient to the acoustic pressure gradient. These values were then compared to a nonlinear theory. Results were very much in agreement except for the region near the n=2 harmonic. An explanation for the discrepancy between theory and experiment appears to lie in the polytropic exponent associated with the gas in the interior of the bubble.
18. Long Pathways for Outgassing Generated by a Rapid and Large Shear Strain of Bubbly Fluids Reducing Effective Viscosity and Affecting Eruption Styles
Namiki, A.; Tanaka, Y.
2015-12-01
The styles of basaltic explosive eruptions have a wide variety, which is usually attributed to the separation of volcanic gas from the surrounding silicate melt. As a mechanism of gas separation, shear deformation has been suggested. However, the bubble shape evolution under large strain at high strain rate and its effects on viscosity have not yet understood well. We thus performed shear deformation experiments of bubbly liquid under high shear rate and large strain with in situ observation of bubble deformation and viscosity measurements. We used syrup solution as a magma analogue whose viscosity of 3, 50, 500 Pa s, similar to that of basaltic magma. We rotated disc-shaped bubbly syrup at shear rates of 0.03-10 s-1 with strains of 3-1000. Experiments show that deformed bubbles coalesce into larger bubbles and finally generate concentric air rings, resulting that the striped shape of air and liquid parts appears. The widths of air rings greatly exceed the bubble sizes and can be long outgassing pathways if those exist in a volcanic conduit. During the evolution of air rings the measured effective viscosity decreases, while after reaching to a steady state, viscous resistance increases again. At this stage, bubble volume and size in the liquid parts become considerably small. Time evolution of bubble size distribution suggests that most of bubbles are assimilated into the air rings and the remnants in the liquid parts break up into small bubbles. Similar shear deformation of bubbly magma could occur in volcanic conduits, which generates large bubbles at a depth where the lower effective viscosity enhances the ascending velocity. The large bubbles may originate Strombolian eruption or suppresses the explosive eruption by making the long outgassing pathways reaching to the Earth's surface. In both cases, bubble free dense melt accumulates at a shallow conduit. Our experiments suggest that, for larger melt viscosity and narrower conduit, the gas separation occurs
19. A three dimensional model of an ultrasound contrast agent gas bubble and its mechanical effects on microvessels
PubMed Central
Hosseinkhah, N.; Hynynen, K.
2012-01-01
versus the vessel rigidity at difference acoustic frequencies. When the acoustic pressure was increased from 52 kPa to 680 kPa, the maximum bubble radius increase by 2.5 folds and the maximum shear and circumferential stress increased by 15.7 and 18.3 folds respectively. The shear stress was largest when the acoustic frequency was higher (3.25 MHz) and the ratio of the vessel radius to the bubble radius was lower. The circumferential stress was largest when the bubble wall was closer to the vessel wall. An oscillating off-center bubble forms a mushroom shape with the most damping on the points closest to the vessel wall. PMID:22252221
20. Luminescence from Collapsing Centimeter Bubbles Expanded by Chemical Reaction
Duplat, Jérôme; Villermaux, Emmanuel
2015-08-01
We report on a new method for realizing an exceptionally strong inertial confinement of a gas in a liquid: A centimetric spherical bubble filled with a reactive gaseous mixture in a liquid is expanded by an exothermic chemical reaction whose products condense in the liquid at the bubble wall. Hence, the cavity formed in this way is essentially empty as it collapses. The temperatures reached at maximum compression, inferred from the cavity radius dynamics and further confirmed by spectroscopic measurements exceed 20 000 K. Because the cavity is typically big, our findings also provide unique space and time resolved sequences of the events accompanying the collapse, notably the development of the inertial instability notoriously known to deter strong compression.
1. Ballistic heat transport in laser generated nano-bubbles.
PubMed
Lombard, Julien; Biben, Thierry; Merabia, Samy
2016-08-01
Nanobubbles generated by laser heated plasmonic nanoparticles are of interest for biomedical and energy harvesting applications. Of utmost importance is the maximal size of these transient bubbles. Here, we report hydrodynamic phase field simulations of the dynamics of laser induced nanobubbles, with the aim to understand which physical processes govern their maximal size. We show that the nanobubble maximal size and lifetime are to a large extent controlled by the ballistic thermal flux which is present inside the bubble. Taking into account this thermal flux, we can reproduce the fluence dependence of the maximal nanobubble radius as reported experimentally. We also discuss the influence of the laser pulse duration on the number of nanobubbles generated and their maximal size. These studies represent a significant step toward the optimization of the nanobubble size, which is of crucial importance for photothermal cancer therapy applications. PMID:27461058
2. Comment on "Acoustical observation of bubble oscillations induced by bubble popping"
Blanc, É.; Ollivier, F.; Antkowiak, A.; Wunenburger, R.
2015-03-01
We have reproduced the experiment of acoustic monitoring of spontaneous popping of single soap bubbles standing in air reported by Ding et al. [2aa Phys. Rev. E 75, 041601 (2007), 10.1103/PhysRevE.75.041601]. By using a single microphone and two different signal acquisition systems recording in parallel the signal at the microphone output, among them the system used by Ding et al., we have experimentally evidenced that the acoustic precursors of bubble popping events detected by Ding et al. actually result from an acausal artifact of the signal processing performed by their acquisition system which lies outside of its prescribed working frequency range. No acoustic precursor of popping could be evidenced with the microphone used in these experiments, whose sensitivity is 1 V Pa-1 and frequency range is 500 Hz-100 kHz.
3. The bubble legacy
Hecht, Jeff
2010-05-01
Imagine an optics company - let's call it JDS Uniphase - with a market capitalization approaching the gross domestic product (GDP) of Ireland. Now imagine it merging with a laser company - say, SDL - that has a stock valuation of 41bn, higher than the GDP of Costa Rica. Finally, imagine a start-up with 109m in venture capital in its pocket but no product to its name (Novalux) turning down an offer of 500m as insufficient. It may be hard to believe, but these tales are true: they occurred in the year 2000 - an era when the laser, fibre-optics and photonics industries were the darlings of the financial world. Such was the madcap nature of that brief period that survivors call it simply "the bubble".
4. Surface Bubble Nucleation Stability
Seddon, James R. T.; Kooij, E. Stefan; Poelsema, Bene; Zandvliet, Harold J. W.; Lohse, Detlef
2011-02-01
Recent research has revealed several different techniques for nanoscopic gas nucleation on submerged surfaces, with findings seemingly in contradiction with each other. In response to this, we have systematically investigated the occurrence of surface nanobubbles on a hydrophobized silicon substrate for various different liquid temperatures and gas concentrations, which we controlled independently. We found that nanobubbles occupy a distinct region of this parameter space, occurring for gas concentrations of approximately 100%-110%. Below the nanobubble region we did not detect any gaseous formations on the substrate, whereas micropancakes (micron wide, nanometer high gaseous domains) were found at higher temperatures and gas concentrations. We moreover find that supersaturation of dissolved gases is not a requirement for nucleation of bubbles.
5. Constrained Vapor Bubble
NASA Technical Reports Server (NTRS)
Huang, J.; Karthikeyan, M.; Plawsky, J.; Wayner, P. C., Jr.
1999-01-01
The nonisothermal Constrained Vapor Bubble, CVB, is being studied to enhance the understanding of passive systems controlled by interfacial phenomena. The study is multifaceted: 1) it is a basic scientific study in interfacial phenomena, fluid physics and thermodynamics; 2) it is a basic study in thermal transport; and 3) it is a study of a heat exchanger. The research is synergistic in that CVB research requires a microgravity environment and the space program needs thermal control systems like the CVB. Ground based studies are being done as a precursor to flight experiment. The results demonstrate that experimental techniques for the direct measurement of the fundamental operating parameters (temperature, pressure, and interfacial curvature fields) have been developed. Fluid flow and change-of-phase heat transfer are a function of the temperature field and the vapor bubble shape, which can be measured using an Image Analyzing Interferometer. The CVB for a microgravity environment, has various thin film regions that are of both basic and applied interest. Generically, a CVB is formed by underfilling an evacuated enclosure with a liquid. Classification depends on shape and Bond number. The specific CVB discussed herein was formed in a fused silica cell with inside dimensions of 3x3x40 mm and, therefore, can be viewed as a large version of a micro heat pipe. Since the dimensions are relatively large for a passive system, most of the liquid flow occurs under a small capillary pressure difference. Therefore, we can classify the discussed system as a low capillary pressure system. The studies discussed herein were done in a 1-g environment (Bond Number = 3.6) to obtain experience to design a microgravity experiment for a future NASA flight where low capillary pressure systems should prove more useful. The flight experiment is tentatively scheduled for the year 2000. The SCR was passed on September 16, 1997. The RDR is tentatively scheduled for October, 1998.
6. The Tidal Radius of the Arches Cluster
Hosek, Matthew; Lu, Jessica R.; Anderson, Jay; Ghez, Andrea; Morris, Mark; Clarkson, William
2015-08-01
At a projected distance of just ˜26 pc from the center of the Milky Way, the Arches cluster allows us to examine the structure of a young massive cluster in the strong tidal environment of the Galactic center (GC). We use the HST WFC3IR camera to conduct an astrometric and photometric study of the outer region of the Arches cluster (R > 6.25”) in order to measure its radial profile. Using proper motions we separate cluster members from field stars down to F153M = 20 mag (˜2.5 M_sun) over a 120” x 120” field of view, covering an area 144 times larger than previous proper motion studies. This is a significant improvement over photometrically-determined cluster membership, which is complicated by the high degree of differential reddening across the field. Using cluster membership probabilities, a derived extinction map, and extensive completeness simulations, we construct the radial profile of the Arches cluster to a radius of ˜80” (˜3.1 pc assuming a distance of 8 kpc). Evidence of mass segregation out to this radius is observed, and no significant tidal tail structure is apparent. We find that the projected radial extent of the Arches cluster is significantly larger than its expected tidal radius. This result suggests either that the cluster is not as close to the GC as previously thought or that it is inflated beyond its nominal tidal radius.
7. Effects of Tissue Stiffness, Ultrasound Frequency, and Pressure on Histotripsy-induced Cavitation Bubble Behavior
PubMed Central
Vlaisavljevich, Eli; Lin, Kuang-Wei; Warnez, Matthew; Singh, Rahul; Mancia, Lauren; Putnam, Andrew J.; Johnsen, Eric; Cain, Charles; Xu, Zhen
2015-01-01
Histotripsy is an ultrasound ablation method that controls cavitation to fractionate soft tissue. In order to effectively fractionate tissue, histotripsy requires cavitation bubbles to rapidly expand from nanometer-sized initial nuclei into bubbles often larger than 50 microns. Using a negative pressure high enough to initiate a bubble cloud and expand bubbles to a sufficient size, histotripsy has been shown capable of completely fractionating soft tissue into acelluar debris resulting in effective tissue removal. Previous work has shown that the histotripsy process is affected by tissue mechanical properties with stiffer tissues showing increased resistance to histotripsy fractionation, which we hypothesize to be caused by impeded bubble expansion in stiffer tissues. In this study, the hypothesis that increases in tissue stiffness causes a reduction in bubble expansion was investigated both theoretically and experimentally. High speed optical imaging was used to capture a series of time delayed images of bubbles produced inside mechanically tunable agarose tissue phantoms using histotripsy pulses produced by 345 kHz, 500 kHz, 1.5 MHz, and 3 MHz histotripsy transducers. The results demonstrated a significant decrease in maximum bubble radius (Rmax) and collapse time (tc) with both increasing Young’s modulus and increasing frequency. Furthermore, results showed that Rmax was not increased by raising the pressure above the intrinsic threshold. Finally, this work demonstrated the potential of using a dual-frequency strategy to modulate the expansion of histotripsy bubbles. Overall, the results of this study improve our understanding of how tissue stiffness and ultrasound parameters affect histotripsy-induced bubble behavior and provide a rational basis to tailor acoustic parameters for treatment of the specific tissues of interest. PMID:25715732
8. Interfacial instability of a condensing vapor bubble in a subcooled liquid
Ueno, I.; Ando, J.; Koiwa, Y.; Saiki, T.; Kaneko, T.
2015-03-01
A special attention is paid to the condensing and collapsing processes of vapor bubble injected into a subcooled pool. We try to extract the vapor-liquid interaction by employing a vapor generator that supplies vapor to the subcooled pool through an orifice instead of using a immersed heating surface to realize vapor bubbles by boiling phenomenon. This system enables ones to detect a spatio-temporal behavior of a single bubble of superheated vapor exposed to a subcooled liquid. In the present study, vapor of water is injected through an orifice at constant flow rate to the subcooled pool of water at the designated degree of subcooling under the atmospheric pressure. The degree of subcooling of the pool is ranged from 0 K to 70 K, and the vapor temperature is kept constant at 101 ∘C. The behaviors of the injected vapor are captured by high-speed camera at frame rate up to 0.3 million frame per second (fps) to track the temporal variation of the vapor bubble shape. It is found that the abrupt collapse of the vapor bubble exposed to the subcooled pool takes place under the condition that the degree of subcooling is greater than around 30 K, and that the abrupt collapse always takes place accompanying the fine disturbances or instability emerged on the free surface. We then evaluate a temporal variation of the apparent volume' of the bubble V under the assumption of the axisymmetric shape of the vapor bubble. It is also found that the instability emerges slightly after the volume of the vapor bubble reaches the maximum value. It is evaluated that the second derivative of the corresponding radius' R of the vapor bubble is negative when the instability appears on the bubble surface, where R = 3√ 3V/4π. We also illustrate that the wave number of the instability on the liquid-vapor interface increases as the degree of subcooling.
9. Effects of tissue stiffness, ultrasound frequency, and pressure on histotripsy-induced cavitation bubble behavior
Vlaisavljevich, Eli; Lin, Kuang-Wei; Warnez, Matthew T.; Singh, Rahul; Mancia, Lauren; Putnam, Andrew J.; Johnsen, Eric; Cain, Charles; Xu, Zhen
2015-03-01
Histotripsy is an ultrasound ablation method that controls cavitation to fractionate soft tissue. In order to effectively fractionate tissue, histotripsy requires cavitation bubbles to rapidly expand from nanometer-sized initial nuclei into bubbles often larger than 50 µm. Using a negative pressure high enough to initiate a bubble cloud and expand bubbles to a sufficient size, histotripsy has been shown capable of completely fractionating soft tissue into acelluar debris resulting in effective tissue removal. Previous work has shown that the histotripsy process is affected by tissue mechanical properties with stiffer tissues showing increased resistance to histotripsy fractionation, which we hypothesize to be caused by impeded bubble expansion in stiffer tissues. In this study, the hypothesis that increases in tissue stiffness cause a reduction in bubble expansion was investigated both theoretically and experimentally. High speed optical imaging was used to capture a series of time delayed images of bubbles produced inside mechanically tunable agarose tissue phantoms using histotripsy pulses produced by 345 kHz, 500 kHz, 1.5 MHz, and 3 MHz histotripsy transducers. The results demonstrated a significant decrease in maximum bubble radius (Rmax) and collapse time (tc) with both increasing Young’s modulus and increasing frequency. Furthermore, results showed that Rmax was not increased by raising the pressure above the intrinsic threshold. Finally, this work demonstrated the potential of using a dual-frequency strategy to modulate the expansion of histotripsy bubbles. Overall, the results of this study improve our understanding of how tissue stiffness and ultrasound parameters affect histotripsy-induced bubble behavior and provide a rational basis to tailor acoustic parameters for treatment of the specific tissues of interest.
10. Ballistic heat transport in laser generated nano-bubbles
Lombard, Julien; Biben, Thierry; Merabia, Samy
2016-08-01
Nanobubbles generated by laser heated plasmonic nanoparticles are of interest for biomedical and energy harvesting applications. Of utmost importance is the maximal size of these transient bubbles. Here, we report hydrodynamic phase field simulations of the dynamics of laser induced nanobubbles, with the aim to understand which physical processes govern their maximal size. We show that the nanobubble maximal size and lifetime are to a large extent controlled by the ballistic thermal flux which is present inside the bubble. Taking into account this thermal flux, we can reproduce the fluence dependence of the maximal nanobubble radius as reported experimentally. We also discuss the influence of the laser pulse duration on the number of nanobubbles generated and their maximal size. These studies represent a significant step toward the optimization of the nanobubble size, which is of crucial importance for photothermal cancer therapy applications.Nanobubbles generated by laser heated plasmonic nanoparticles are of interest for biomedical and energy harvesting applications. Of utmost importance is the maximal size of these transient bubbles. Here, we report hydrodynamic phase field simulations of the dynamics of laser induced nanobubbles, with the aim to understand which physical processes govern their maximal size. We show that the nanobubble maximal size and lifetime are to a large extent controlled by the ballistic thermal flux which is present inside the bubble. Taking into account this thermal flux, we can reproduce the fluence dependence of the maximal nanobubble radius as reported experimentally. We also discuss the influence of the laser pulse duration on the number of nanobubbles generated and their maximal size. These studies represent a significant step toward the optimization of the nanobubble size, which is of crucial importance for photothermal cancer therapy applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/C6NR02144A
11. Proton radius from electron scattering data
Higinbotham, Douglas W.; Kabir, Al Amin; Lin, Vincent; Meekins, David; Norum, Blaine; Sawatzky, Brad
2016-05-01
Background: The proton charge radius extracted from recent muonic hydrogen Lamb shift measurements is significantly smaller than that extracted from atomic hydrogen and electron scattering measurements. The discrepancy has become known as the proton radius puzzle. Purpose: In an attempt to understand the discrepancy, we review high-precision electron scattering results from Mainz, Jefferson Lab, Saskatoon, and Stanford. Methods: We make use of stepwise regression techniques using the F test as well as the Akaike information criterion to systematically determine the predictive variables to use for a given set and range of electron scattering data as well as to provide multivariate error estimates. Results: Starting with the precision, low four-momentum transfer (Q2) data from Mainz (1980) and Saskatoon (1974), we find that a stepwise regression of the Maclaurin series using the F test as well as the Akaike information criterion justify using a linear extrapolation which yields a value for the proton radius that is consistent with the result obtained from muonic hydrogen measurements. Applying the same Maclaurin series and statistical criteria to the 2014 Rosenbluth results on GE from Mainz, we again find that the stepwise regression tends to favor a radius consistent with the muonic hydrogen radius but produces results that are extremely sensitive to the range of data included in the fit. Making use of the high-Q2 data on GE to select functions which extrapolate to high Q2, we find that a Padé (N =M =1 ) statistical model works remarkably well, as does a dipole function with a 0.84 fm radius, GE(Q2) =(1+Q2/0.66 GeV2) -2 . Conclusions: Rigorous applications of stepwise regression techniques and multivariate error estimates result in the extraction of a proton charge radius that is consistent with the muonic hydrogen result of 0.84 fm; either from linear extrapolation of the extremely-low-Q2 data or by use of the Padé approximant for extrapolation using a larger
12. Interfacial area transport in bubbly flow
SciTech Connect
Ishii, M.; Wu, Q.; Revankar, S.T.
1997-12-31
In order to close the two-fluid model for two-phase flow analyses, the interfacial area concentration needs to be modeled as a constitutive relation. In this study, the focus was on the investigation of the interfacial area concentration transport phenomena, both theoretically and experimentally. The interfacial area concentration transport equation for air-water bubbly up-flow in a vertical pipe was developed, and the models for the source and sink terms were provided. The necessary parameters for the experimental studies were identified, including the local time-averaged void fraction, interfacial area concentration, bubble interfacial velocity, liquid velocity and turbulent intensity. Experiments were performed with air-water mixture at atmospheric pressure. Double-sensor conductivity probe and hot-film probe were employed to measure the identified parameters. With these experimental data, the preliminary model evaluation was carried out for the simplest form of the developed interfacial area transport equation, i.e., the one-dimensional transport equation.
13. On solar radius measurements with PICARD
Meftah, M.; Irbah, A.; Hauchecorne, A.; Corbard, T.; Hochedez, J. F.
2014-12-01
Solar diameter measurements performed from the ground for several decades seem to indicate a relation between the solar diameter and the solar activity. If this relationship is confirmed, it would be possible to use measurements of solar diameter as a proxy of solar activity in the past since the 1715 solar eclipses, and to use this input for the reconstruction of solar irradiance in climate models. However the interpretation of ground observations is controversial, ground-based measurements being affected by refraction, by atmospheric turbulence, and perhaps by atmospheric aerosols scattering. The only way to be free from atmospheric effects is to measure from space. This is the reason why, since the beginning, the PICARD program included a space and a ground component set up at the Calern site of the Observatoire de la Côte dAzur. During the last 4 years, the PICARD space mission has been used for observing the apparent solar diameter. First results of the astrometry program include a study of the June 2012 Venus transit for solar diameter determination. From this, the value of the solar radius from one astronomical unit was found to be equal to 959.86 arc-seconds at 607.1 nm. However, concerning observed variations in time of the solar radius, instrumental effects affect the results. Space is known to represent a harsh environment for optical instruments. Nevertheless, we can use the PICARD data to monitor the solar radius variation. PICARD aims to perpetuate historical series of the solar radius measurements, in particular during the solar cycle 24. This paper presents solar radius measurements obtained with PICARD.
14. From bubble bursting to droplet evaporation in the context of champagne aerosols
Seon, Thomas; Ghabache, Elisabeth; Antkowiak, Arnaud; Liger-Belair, Gerard
2015-11-01
As champagne or sparkling wine is poured into a glass, a myriad of ascending bubbles collapse and therefore radiate a multitude of tiny droplets above the free surface into the form of very characteristic and refreshing aerosols. Because these aerosols have been found to hold the organoleptic essence'' of champagne they are believed to play a crucial role in the flavor release in comparison with that from a flat wine for example. Based on the model experiment of a single bubble bursting in idealized champagnes, the velocity, radius and maximum height of the first jet drop following bubble collapse have been characterized, with varying bubble size and liquid properties in the context of champagne aerosols. Using the experimental results and simple theoretical models for drop and surface evaporation, we show that bubble bursting aerosols drastically enhance the transfer of liquid in the atmosphere with respect to a flat liquid surface. Contrary to popular opinion, we exhibit that small bubbles are negative in terms of aroma release, and we underline bubble radii enabling to optimize the droplet height and evaporation in the whole range of champagne properties. These results pave the road to the fine tuning of champagne aroma diffusion, a major issue of the sparkling wine industry.
15. Molecular Dynamics Simulation of Cascade-Induced Ballistic Helium Resolutioning from Bubbles in Iron
SciTech Connect
Stoller, Roger E
2013-01-01
Molecular dynamics simulations have been used to assess the ability of atomic displacement cascades to eject helium from small bubbles in iron. This study of the ballistic resolutioning mechanism employed a recently-developed Fe-He interatomic potential in concert with an iron potential developed by Ackland and co-workers. The primary variables examined were: irradiation temperature (100 and 600K), cascade energy (5 and 20 keV), bubble radius (0.5 and 1.0 nm), and He-to-vacancy ratio in the bubble (0.25, 0.5 and 1.0). Systematic trends were observed for each of these variables. For example, ballistic resolutioning leads to a greater number of helium atoms being displaced from larger bubbles and from bubbles that have a higher He/vacancy ratio (bubble pressure). He resolutioning was reduced at 600K relative to 100K, and for 20 keV cascades relative to 5 keV cascades. Overall, the results indicate a modest level of He removal by ballistic resolutioning. The results can be used to provide guidance in selection of a resolution parameter that can be employed in cluster dynamics models to predict the bubble size distribution that evolves under irradiation.
16. Combination syringe provides air-free blood samples
NASA Technical Reports Server (NTRS)
Pool, S. L.
1970-01-01
Standard syringe and spinal needle are combined in unique manner to secure air-free blood samples. Combination syringe obtains air free samples because air bubbles become insignificant when samples greater than 1 cc are drawn.
17. Experimental study on the interaction between bubble and free surface using a high-voltage spark generator
Zhang, S.; Wang, S. P.; Zhang, A. M.
2016-03-01
The experimental studies presented in this paper attempt to supply a reasonable comprehensive explanation for the key feature of the collapse bubble and the complex nature of the raised free surface. Six distinctive patterns of free surface motion were identified for bubbles initiated at different γf (the non-dimensional bubble-free surface distance scaled with the maximum bubble radius). Special features such as "breaking wrinkles," "spraying water film," and other unstable phenomena were observed with free surface motions, which were hardly captured by a boundary integral scheme. Parameters defining the shape of the free surface, such as the spike height Hspike, the spike width Wbase, and the skirt height Hspray, are measured and analyzed against γf. Different voltages were used to generate bubbles with varies sizes, while the bubble and free surface motion patterns appeared to be largely independent of the bubble size. Finally, collapsing bubble shape, centroid migration, period of bubble oscillation, and jet tip velocity at different γf are investigated and noticeable variation trends are found.
18. Theoretical model of ice nucleation induced by acoustic cavitation. Part 1: Pressure and temperature profiles around a single bubble.
PubMed
Cogné, C; Labouret, S; Peczalski, R; Louisnard, O; Baillon, F; Espitalier, F
2016-03-01
This paper deals with the inertial cavitation of a single gas bubble in a liquid submitted to an ultrasonic wave. The aim was to calculate accurately the pressure and temperature at the bubble wall and in the liquid adjacent to the wall just before and just after the collapse. Two different approaches were proposed for modeling the heat transfer between the ambient liquid and the gas: the simplified approach (A) with liquid acting as perfect heat sink, the rigorous approach (B) with liquid acting as a normal heat conducting medium. The time profiles of the bubble radius, gas temperature, interface temperature and pressure corresponding to the above models were compared and important differences were observed excepted for the bubble size. The exact pressure and temperature distributions in the liquid corresponding to the second model (B) were also presented. These profiles are necessary for the prediction of any physical phenomena occurring around the cavitation bubble, with possible applications to sono-crystallization. PMID:26044460
19. Phase transitions in multicomponent systems at the nano-scale: the existence of a minimal bubble size
Wilhelmsen, Oivind; Bedeaux, Dick; Kjelstrup, Signe; Reguera, David
2014-03-01
The formation of nanoscale droplets/bubbles from a metastable bulk phase is still connected to many unresolved scientific questions. In this work we analyze the stability of multicomponent liquid droplets and bubbles in closed Nj, V, T systems (total mass of components, total volume and temperature). To investigate this problem, square gradient theory combined with an accurate equation of state is used. We compare the results from the square gradient model to the macroscopic capillary description. We find that both predict a finite threshold size for droplets/bubbles. The work reveals a metastable region close to the minimal droplet/bubble radius. We find that the liquid compressibility is crucial for the existence of this minimum threshold size for bubble formation.
20. Bubble Growth in Lunar Basalts
Zhang, Y.
2009-05-01
Although Moon is usually said to be volatile-"free", lunar basalts are often vesicular with mm-size bubbles. The vesicular nature of the lunar basalts suggests that they contained some initial gas concentration. A recent publication estimated volatile concentrations in lunar basalts (Saal et al. 2008). This report investigates bubble growth on Moon and compares with that on Earth. Under conditions relevant to lunar basalts, bubble growth in a finite melt shell (i.e., growth of multiple regularly-spaced bubbles) is calculated following Proussevitch and Sahagian (1998) and Liu and Zhang (2000). Initial H2O content of 700 ppm (Saal et al. 2008) or lower is used and the effect of other volatiles (such as carbon dioxide, halogens, and sulfur) is ignored. H2O solubility at low pressures (Liu et al. 2005), concentration-dependent diffusivity in basalt (Zhang and Stolper 1991), and lunar basalt viscosity (Murase and McBirney 1970) are used. Because lunar atmospheric pressure is essentially zero, the confining pressure on bubbles is completely supplied by the overlying magma. Due to low H2O content in lunar basaltic melt (700 ppm H2O corresponds to a saturation pressure of 75 kPa), H2O bubbles only grow in the upper 16 m of a basalt flow or lake. A depth of 20 mm corresponds to a confining pressure of 100 Pa. Hence, vesicular lunar rocks come from very shallow depth. Some findings from the modeling are as follows. (a) Due to low confining pressure as well as low viscosity, even though volatile concentration is very low, bubble growth rate is extremely high, much higher than typical bubble growth rates in terrestrial melts. Hence, mm-size bubbles in lunar basalts are not strange. (b) Because the pertinent pressures are so low, bubble pressure due to surface tension plays a main role in lunar bubble growth, contrary to terrestrial cases. (c) Time scale to reach equilibrium bubble size increases as the confining pressure increases. References: (1) Liu Y, Zhang YX (2000) Earth
1. Electron bubbles in helium clusters. I. Structure and energetics.
PubMed
Rosenblit, Michael; Jortner, Joshua
2006-05-21
In this paper we present a theoretical study of the structure, energetics, potential energy surfaces, and energetic stability of excess electron bubbles in ((4)He)(N) (N=6500-10(6)) clusters. The subsystem of the helium atoms was treated by the density functional method. The density profile was specified by a void (i.e., an empty bubble) at the cluster center, a rising profile towards a constant interior value (described by a power exponential), and a decreasing profile near the cluster surface (described in terms of a Gudermannian function). The cluster surface density profile width (approximately 6 A) weakly depends on the bubble radius R(b), while the interior surface profile widths (approximately 4-8 A) increase with increasing R(b). The cluster deformation energy E(d) accompanying the bubble formation originates from the bubble surface energy, the exterior cluster surface energy change, and the energy increase due to intracluster density changes, with the latter term providing the dominant contribution for N=6500-2 x 10(5). The excess electron energy E(e) was calculated at a fixed nuclear configuration using a pseudopotential method, with an effective (nonlocal) potential, which incorporates repulsion and polarization effects. Concurrently, the energy V(0) of the quasi-free-electron within the deformed cluster was calculated. The total electron bubble energies E(t)=E(e)+E(d), which represent the energetic configurational diagrams of E(t) vs R(b) (at fixed N), provide the equilibrium bubble radii R(b) (c) and the corresponding total equilibrium energies E(t) (e), with E(t) (e)(R(e)) decreasing (increasing) with increasing N (i.e., at N=6500, R(e)=13.5 A and E(t) (e)=0.86 eV, while at N=1.8 x 10(5), R(e)=16.6 A and E(t) (e)=0.39 eV). The cluster size dependence of the energy gap (V(0)-E(t) (e)) allows for the estimate of the minimal ((4)He)(N) cluster size of N approximately 5200 for which the electron bubble is energetically stable. PMID:16729823
2. Micro-bubble drag reduction on a high speed vessel model
Yanuar; Gunawan; Sunaryo; Jamaluddin, A.
2012-09-01
Ship hull form of the underwater area strongly influences the resistance of the ship. The major factor in ship resistance is skin friction resistance. Bulbous bows, polymer paint, water repellent paint (highly water-repellent wall), air injection, and specific roughness have been used by researchers as an attempt to obtain the resistance reduction and operation efficiency of ships. Micro-bubble injection is a promising technique for lowering frictional resistance. The injected air bubbles are supposed to somehow modify the energy inside the turbulent boundary layer and thereby lower the skin friction. The purpose of this study was to identify the effect of injected micro bubbles on a navy fast patrol boat (FPB) 57 m type model with the following main dimensions: L=2 450 mm, B=400 mm, and T=190 mm. The influence of the location of micro bubble injection and bubble velocity was also investigated. The ship model was pulled by an electric motor whose speed could be varied and adjusted. The ship model resistance was precisely measured by a load cell transducer. Comparison of ship resistance with and without micro-bubble injection was shown on a graph as a function of the drag coefficient and Froude number. It was shown that micro bubble injection behind the mid-ship is the best location to achieve the most effective drag reduction, and the drag reduction caused by the micro-bubbles can reach 6%-9%.
3. Radial oscillation of a gas bubble in a fluid as a problem in canonical perturbation theory
Stephens, James
2005-11-01
The oscillation of a gas bubble is in a fluid is of interest in many areas of physics and technology. Lord Rayleigh treated the pressure developed in the collapse of cavitation bubbles and developed an expression for the collapse period. Minnaert developed a harmonic oscillator approximation to bubble oscillation in his study of the sound produced by running water. Oscillating bubbles are important to oceanographers studying the sound spectrum produced by water waves, geophysicists employing air guns as acoustic probes, mechanical engineers concerned with erosion of turbine blades, and military engineers concerned with the acoustic signatures developed by the propeller screws of ships and submarines. For the oceanographer, Minnaert's approximation is useful, for the latter two examples, Lord Rayleigh's analysis is appropriate. On the one hand, a bubble can be treated as a harmonic oscillator in the small amplitude regime, whereas even in the relatively moderate pressure regime characteristic of air guns the oscillation is strongly nonlinear and amplitude dependent. Is it possible to develop an analytic approximation that affords insight into the behavior of a bubble beyond the harmonic approximation of Minnaert? In this spirit, the free radial oscillation of a gas bubble in a fluid is treated as a problem in canonical perturbation theory. Several orders of the expansion are determined in order to explore the dependence of the oscillation frequency with bubble amplitude. The expansion to second order is inverted to express the time dependence of the oscillation.
4. Bubble splitting in bifurcating tubes: a model study of cardiovascular gas emboli transport.
PubMed
Calderón, Andrés J; Fowlkes, J Brian; Bull, Joseph L
2005-08-01
The transport of long gas bubbles, suspended in liquid, through symmetric bifurcations, is investigated experimentally and theoretically as a model of cardiovascular gas bubble transport in air embolism and gas embolotherapy. The relevant dimensionless parameters in the models match the corresponding values for arteries and arterioles. The effects of roll angle (the angle the plane of the bifurcation makes with the horizontal), capillary number (a dimensionless indicator of flow), and bubble volume (or length) on the splitting of bubbles as they pass through the bifurcation are examined. Splitting is observed to be more homogenous at higher capillary numbers and lower roll angles. It is shown that, at nonzero roll angles, there is a critical value of the capillary number below which the bubbles do not split and are transported entirely into the upper branch. The value of the critical capillary number increases with roll angle and parent tube diameter. A unique bubble motion is observed at the critical capillary number and for slightly slower flows: the bubble begins to split, the meniscus in the lower branch then moves backward, and finally the entire bubble enters the upper branch. These findings suggest that, in large vessels, emboli tend to be transported upward unless flow is unusually strong but that a more homogeneous distribution of emboli occurs in smaller vessels. This corresponds to previous observations that air emboli tend to lodge in the upper regions of the lungs and suggests that relatively uniform infarction of tumors by gas embolotherapy may be possible. PMID:15790688
5. Bubble Rise and Break-Up in Volcanic Conduits
Soldati, A.; Cashman, K. V.; Rust, A.; Rosi, M.
2013-12-01
The continual passive degassing occurring at open-vent mafic volcanoes is often punctuated by bursts of active degassing. The latter are generally thought to be the result of slug flow: large, conduit-filling bubbles periodically rising up the feeder conduit and bursting at the magma-air interface. Existing models of volcanic degassing systems make the simplifying assumption that the conduit is cylindrical; however, while this may be true at shallow levels, a flaring probably connects it to a dyke-like geometry at depth. The overall goal of this research is to assess the influence of conduit geometry on the speed and stability of bubbles rising in open-vent systems, and ultimately to devise a model to infer conduit shape from emerging bubbles size. In order to do that an analogue experimental approach was used. All of the experiments were two-phase (melt+volatiles); the analogue materials of choice were golden syrup-water mixtures ranging in viscosity from 10-1 to 104 Pa*s and air. Two experimental apparatuses were used: a bi-dimensional and a tri-dimensional one. The bi-dimensional set-up is a cell made of two flat transparent PVC plates (44x23cm) 10mm or 5mm apart (the front one having a hole at the bottom permitting bubble injection) containing a variety of parallelepipeds apt to outline different plumbing system geometries. The tri-dimensional one consists of a cylindrical tube (r=1,5cm; l=7cm) allowing bubble injection through the bottom rubber tap and terminating into a square tank (l=22cm). Results indicate that conduit geometry directly controls the slug rise velocity and the surrounding liquid descending speed, which in turn control the slug stability. Small enough bubbles simply deform as they go through the flaring, while bigger ones split into two daughter bubbles. A regime diagram has been constructed, illustrating the bubble break-up threshold dependence on the flare geometry and initial slug size, the two main controlling factors. The phenomenon of
6. Discussion on the Applicability of Rayleigh-Plesset Equation for a Nano-scale bubble using Molecular Dynamics Simulation
Tsuda, Shin-Ichi; Ogasawara, Kazuki; Itakura, Takumi
2014-11-01
Multi-phase flows such as cavitation and boiling have much variety on the scale in time and space compared with single phase flows. It is necessary to recognize the multi-scale structure accurately to construct a sophisticated numerical method for the prediction of various multi-phase flow phenomena. In this point of view, clarification of the valid range of continuum mechanics would be very important. Here, an interesting problem in the case of cavitation is, to what extent Rayleigh-Plesset (R-P) equation, which describes the radius change of a spherical bubble under a pressure given at far from the bubble, can express the behavior of a tiny bubble quantitatively. In this work, we discussed the validity of the application of R-P equation to a nano-scale bubble using Molecular Dynamics (MD) simulation. In the simulation, liquid argon at a decompressed state in a cubic domain was simulated. As a result, a nano-scale bubble was generated after a waiting time, and it rapidly grew to several nanometers, and it reached to an equilibrium state showing a transient behavior. We compared the bubble radius change observed in the MD simulation with the numerical result of R-P equation, and confirmed that R-P equation can well predict the behavior of such tiny bubble.
7. Near Surface Vapor Bubble Layers in Buoyant Low Stretch Burning of Polymethylmethacrylate
NASA Technical Reports Server (NTRS)
Olson, Sandra L.; Tien, J. S.
1999-01-01
Large-scale buoyant low stretch stagnation point diffusion flames over solid fuel (polymethylmethacrylate) were studied for a range of aerodynamic stretch rates of 2-12/ sec which are of the same order as spacecraft ventilation-induced stretch in a microgravity environment. An extensive layer of polymer material above the glass transition temperature is observed. Unique phenomena associated with this extensive glass layer included substantial swelling of the burning surface, in-depth bubble formation, and migration and/or elongation of the bubbles normal to the hot surface. The bubble layer acted to insulate the polymer surface by reducing the effective conductivity of the solid. The reduced in-depth conduction stabilized the flame for longer than expected from theory neglecting the bubble layer. While buoyancy acts to move the bubbles deeper into the molten polymer, thermocapillary forces and surface regression both act to bring the bubbles to the burning surface. Bubble layers may thus be very important in low gravity (low stretch) burning of materials. As bubbles reached the burning surface, monomer fuel vapors jetted from the surface, enhancing burning by entraining ambient air flow. Popping of these bubbles at the surface can expel burning droplets of the molten material, which may increase the fire propagation hazards at low stretch rates.
8. Collective bubble oscillations as a component of surf infrasound.
PubMed
Park, Joseph; Garcés, Milton; Fee, David; Pawlak, Geno
2008-05-01
Plunging surf is a known generator of infrasound, though the mechanisms have not been clearly identified. A model based on collective bubble oscillations created by demise of the initially entrained air pocket is examined. Computed spectra are compared to infrasound data from the island of Kauai during periods of medium, large, and extreme surf. Model results suggest that bubble oscillations generated by plunging waves are plausible generators of infrasound, and that dynamic bubble plume evolution on a temporal scale comparable to the breaking wave period may contribute to the broad spectral lobe of dominant infrasonic energy observed in measured data. Application of an inverse model has potential to characterize breaking wave size distributions, energy, and temporal changes in seafloor morphology based on remotely sensed infrasound. PMID:18529169
9. Investigation of Bubble-Slag Layer Behaviors with Hybrid Eulerian-Lagrangian Modeling and Large Eddy Simulation
Li, Linmin; Li, Baokuan
2016-03-01
In ladle metallurgy, bubble-liquid interaction leads to complex phase structures. Gas bubble behavior, as well as the induced slag layer behavior, plays a significant role in the refining process and the steel quality. In the present work, a mathematical model using the large eddy simulation (LES) is developed to investigate the bubble transport and slag layer behavior in a water model of an argon-stirred ladle. The Eulerian volume of fluid model is adopted to track the liquid steel-slag-air free surfaces while the Lagrangian discrete phase model is used for tracking and handling the dynamics of discrete bubbles. The bubble coalescence is considered using O'Rourke's algorithm to solve the bubble diameter redistribution and bubbles are removed after leaving the air-liquid interface. The turbulent liquid flow that is induced by bubble-liquid interaction is solved by LES. The slag layer fluactuation, slag droplet entrainment and spout eye open-close phenomenon are well revealed. The bubble diameter distribution and the spout eye size are compared with the experiment. The results show that the hybrid Eulerian-Lagrangian-LES model provides a valid modeling framework to predict the unsteady gas bubble-slag layer coupled behaviors.
SciTech Connect
Swift, D. C.; Eggert, J. H.; Hicks, D. G.; Hamel, S.; Caspersen, K.; Schwegler, E.; Collins, G. W.; Nettelmann, N.; Ackland, G. J.
2012-01-01
For planets other than Earth, particularly exoplanets, interpretation of the composition and structure depends largely on comparing the mass and radius with the composition expected given their distance from the parent star. The composition implies a mass-radius relation which relies heavily on equations of state calculated from electronic structure theory and measured experimentally on Earth. We lay out a method for deriving and testing equations of state, and deduce mass-radius and mass-pressure relations for key, relevant materials whose equation of state (EOS) is reasonably well established, and for differentiated Fe/rock. We find that variations in the EOS, such as may arise when extrapolating from low-pressure data, can have significant effects on predicted mass-radius relations and on planetary pressure profiles. The relations are compared with the observed masses and radii of planets and exoplanets, broadly supporting recent inferences about exoplanet structures. Kepler-10b is apparently 'Earth-like', likely with a proportionately larger core than Earth's, nominally 2/3 of the mass of the planet. CoRoT-7b is consistent with a rocky mantle over an Fe-based core which is likely to be proportionately smaller than Earth's. GJ 1214b lies between the mass-radius curves for H{sub 2}O and CH{sub 4}, suggesting an 'icy' composition with a relatively large core or a relatively large proportion of H{sub 2}O. CoRoT-2b is less dense than the hydrogen relation, which could be explained by an anomalously high degree of heating or by higher than assumed atmospheric opacity. HAT-P-2b is slightly denser than the mass-radius relation for hydrogen, suggesting the presence of a significant amount of matter of higher atomic number. CoRoT-3b lies close to the hydrogen relation. The pressure at the center of Kepler-10b is 1.5{sup +1.2}{sub -1.0} TPa. The central pressure in CoRoT-7b is probably close to 0.8 TPa, though may be up to 2 TPa. These pressures are accessible by planar
11. Aspherical bubble dynamics and oscillation times
SciTech Connect
Vogel, A.; Noack, J.; Chapyak, E.J.; Godwin, R.P.
1999-06-01
The cavitation bubbles common in laser medicine are rarely perfectly spherical and are often located near tissue boundaries, in vessels, etc., which introduce aspherical dynamics. Here, novel features of aspherical bubble dynamics are explored by time-resolved photography and numerical simulations. The growth-collapse period of cylindrical bubbles of large aspect ratio (length:diameter {approximately}20) differs only slightly from twice the Rayleigh collapse time for a spherical bubble with an equivalent maximum volume. This fact justifies using the temporal interval between the acoustic signals emitted upon bubble creation and collapse to estimate the maximum bubble volume. As a result, hydrophone measurements can provide an estimate of the bubble size and energy even for aspherical bubbles. The change of the oscillation period of bubbles near solid walls and elastic (tissue-like) boundaries relative to that of isolated spherical bubbles is also investigated.
12. Transient bubbles, bublets and breakup
Keen, Giles; Blake, John
1999-11-01
The non-spherical nature of the collapse of bubbles has important ramifications in many practical situations such as ultrasonic cleaning, tanning of leather, and underwater explosions. In particular the high speed liquid jet that can thread a collapsing bubble is central to the functional performance. An impressive photographic record of a liquid jet was obtained by Crum using a bubble situated in the vicinity of a platform oscillating vertically at a frequency of 60 Hz. A boundary integral method is used to model this situation and is found to closely mimic some of the observations. However, a slight variation of parameters or a change in the phase of the driving frequency can lead to dramatically different bubble behaviour, a feature also observed by Crum.
13. Bubble nucleation in stout beers
Lee, W. T.; McKechnie, J. S.; Devereux, M. G.
2011-05-01
Bubble nucleation in weakly supersaturated solutions of carbon dioxide—such as champagne, sparkling wines, and carbonated beers—is well understood. Bubbles grow and detach from nucleation sites: gas pockets trapped within hollow cellulose fibers. This mechanism appears not to be active in stout beers that are supersaturated solutions of nitrogen and carbon dioxide. In their canned forms these beers require additional technology (widgets) to release the bubbles which will form the head of the beer. We extend the mathematical model of bubble nucleation in carbonated liquids to the case of two gases and show that this nucleation mechanism is active in stout beers, though substantially slower than in carbonated beers and confirm this by observation. A rough calculation suggests that despite the slowness of the process, applying a coating of hollow porous fibers to the inside of a can or bottle could be a potential replacement for widgets.
14. Pulling bubbles from a bath
Kao, Justin C. T.; Blakemore, Andrea L.; Hosoi, A. E.
2010-06-01
Deposition of bubbles on a wall withdrawn from a liquid bath is a phenomenon observed in many everyday situations—the foam lacing left behind in an emptied glass of beer, for instance. It is also of importance to the many industrial processes where uniformity of coating is desirable. We report work on an idealized version of this situation, the drag-out of a single bubble in Landau-Levich-Derjaguin flow. We find that a well-defined critical wall speed exists, separating the two regimes of bubble persistence at the meniscus and bubble deposition on the moving wall. Experiments show that this transition occurs at Ca∗˜Bo0.73. A similar result is obtained theoretically by balancing viscous stresses and gravity.
15. Modeling the Local Bubble
Cox, D. P.
Modeling the Local Bubble is one of those activities fraught with danger. It is very easy to be too naive, to fail to consider the dependence of the model on assumptions about the nearby ambient state, or the likelihood of such a structure. It is similarly easy to become so caught up in the details of the vicinity that it is unclear where to begin a necessarily idealized modeling effort. And finally, it is important to remember that the data we have may in some cases be lying to us, and that we have not yet learned to read their facial expressions quite carefully enough. That said, I've tried in this paper to be helpful to those who may wish to take the risks. I surveyed the very most basic stories that the data seem to tell, and pointed out the standard coincidences that may be telling us a lot about what is happening, but may turn out once again to have been just coincidences. I've described 5 distinct conceptions that in one flavor or another pretty well survey the collection of mental images that have so far been carried by those who've attempted models. One may be right, or something entirely different may be more appropriate. It's at least vital to realize that a conception comes first, followed by a simplified model of details. I've also included a long list of questions directed at observers. Some have partial answers, some one wouldn't know today quite how to approach. But it is a list that students of the soft x-ray background, interstellar absorption lines, possible instrumentation, and the heliosphere may wish to review from time to time, just to see whether they can figure out how to be more helpful. There is another list for modelers, things the models must address, however-so-flimsily if necessary, because there are strong observational constraints (and stronger ones coming) on what can and cannot be present in the local ISM. To that I've added a few remarks concerning x-ray emission coming from beyond the Local Bubble, and another few on how x
16. Maximum likelihood analysis of bubble incidence for mixed gas diving.
PubMed
Tikuisis, P; Gault, K; Carrod, G
1990-03-01
The method of maximum likelihood has been applied to predict the incidence of bubbling in divers for both air and helium diving. Data were obtained from 108 air man-dives and 622 helium man-dives conducted experimentally in a hyperbaric chamber. Divers were monitored for bubbles using Doppler ultrasonics during the period from surfacing until approximately 2 h after surfacing. Bubble grades were recorded according to the K-M code, and the maximum value in the precordial region for each diver was used in the likelihood analysis. Prediction models were based on monoexponential gas kinetics using one and two parallel-compartment configurations. The model parameters were of three types: gas kinetics, gas potency, and compartment gain. When the potency of the gases was not distinguished, the risk criterion used was inherently based on the gas supersaturation ratio, otherwise it was based on the potential bubble volume. The two-compartment model gave a significantly better prediction than the one-compartment model only if the kinetics of nitrogen and helium were distinguished. A further significant improvement with the two-compartment model was obtained when the potency of the two gases was distinguished, thereby making the potential bubble volume criterion a better choice than the gas pressure criterion. The results suggest that when the method of maximum likelihood is applied for the prediction of the incidence of bubbling, more than one compartment should be used and if more than one is used consideration should be given to distinguishing the potencies of the inert gases. PMID:2181767
17. How does a bubble chamber work?
SciTech Connect
Konstantinov, D.; Homsi, W.; Luzuriaga, J.; Su, C.K.; Weilert, M.A.; Maris, H.J.
1998-11-01
A charged particle passing through a bubble chamber produces a track of bubbles. The way in which these bubbles are produced has been a matter of some controversy. The authors consider the possibility that in helium and hydrogen bubble chambers the production of bubbles is primarily a mechanical process, rather than a thermal process as has often been assumed. The model the authors propose gives results which are in excellent agreement with experiment.
18. Bubble gum simulating abdominal calcifications.
PubMed
Geller, E; Smergel, E M
1992-01-01
CT examination of the abdomens of two children demonstrated sites of high attenuation in the stomach, which were revealed to be bubble gum. Investigation of the CT appearance of samples of chewing gum showed that it consistently has high attenuation (178-345 HU). The attenuation of gum base, which contains calcium carbonate, was 476 HU. In addition, examination of a volunteer who had swallowed bubble gum confirmed the CT appearance. PMID:1523059
19. Shape and size of methane bubbles in muddy aquatic sediments and their dependence on sediment fracture toughness: a modeling approach
Katsman, Regina
2014-05-01
Shallow gassy marine sediments abundantly found on continental margins of Israel and worldwide, are a source of a major concern for their contribution to the destabilization of coastal and marine infrastructure, air pollution, and global warming. Bubbles are different in the different sediment types. Size of the bubbles residing in the fine-grained muddy sediment exceeds significantly the grain size of sediment, and its shape can be approximated by a large oblate spheroid surrounded by sediment saturated with water. Experimental results indicate that bubble growth is accompanied by fracturing of the fine-grained muddy sediment. Modeling reveals that fracture toughness of the muddy sediments significantly affects bubble shape and size evolution prior its ascent. Small fracture toughness is responsible for generation of the small bubbles with highly asymmetric configuration and with fracturing concentrated mostly on the bubble head. In contrast, bigger fracture toughness is responsible for generation of the large, more symmetric bubbles. Moreover, growing bubble demonstrates a positive allometry resulting in a bigger rate of growth of its surface area that is responsible for the effectiveness of the solute supply from pore water to the bubble interior. This scaling demonstrates a strong correlation with sediment fracture toughness as well. Cross-section of the buoyant bubbles evolves from the elliptic profile to the one resembling an 'inverted tear drop'. Calculated bubbles characteristics in different sediments types demonstrate a good agreement with values reported in the literature.
20. Ultrasonic excitation of a bubble inside a deformable tube: implications for ultrasonically induced hemorrhage.
PubMed
Miao, Hongyu; Gracewski, Sheryl M; Dalecki, Diane
2008-10-01
Various independent investigations indicate that the presence of microbubbles within blood vessels may increase the likelihood of ultrasound-induced hemorrhage. To explore potential damage mechanisms, an axisymmetric coupled finite element and boundary element code was developed and employed to simulate the response of an acoustically excited bubble centered within a deformable tube. As expected, the tube mitigates the expansion of the bubble. The maximum tube dilation and maximum hoop stress were found to occur well before the bubble reached its maximum radius. Therefore, it is not likely that the expanding low pressure bubble pushes the tube wall outward. Instead, simulation results indicate that the tensile portion of the acoustic excitation plays a major role in tube dilation and thus tube rupture. The effects of tube dimensions (tube wall thickness 1-5 microm), material properties (Young's modulus 1-10 MPa), ultrasound frequency (1-10 MHz), and pressure amplitude (0.2-1.0 MPa) on bubble response and tube dilation were investigated. As the tube thickness, tube radius, and acoustic frequency decreased, the maximum hoop stress increased, indicating a higher potential for tube rupture and hemorrhage. PMID:19062875 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7565942406654358, "perplexity": 2292.972360352138}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-04/segments/1484560280280.6/warc/CC-MAIN-20170116095120-00007-ip-10-171-10-70.ec2.internal.warc.gz"} |
https://www.meritnation.com/ask-answer/question/ten-students-were-selected-from-a-school-on-the-basis-of-val/matrices/7176213 | # Ten students were selected from a school on the basis of values for giving awards and were divided into three groups. The first group comprises hard workers,the second group has honest and law abiding students and the third group consists vigilant and obedient students. Double the number of students of the first group added to the number in the second group gives 13, while the combined strength of first and second group is 4 times that of the third group. Find the number of students in each group.
Let the number of student is each group is x , y and z respectively
Hence from the question x + y + z = 10
And 2x + y = 13
And x + y = 4z
Hence forming a matrix ,we get
AX = B
Hence X = A-1B
And |A| = 1(-4-0) -1(-8 -0) + 1(2-1) = -4 + 8 + 1 = 5
And A11 = ( -4 -0 ) = -4 , A12 = -1(-8 -0 ) = 8 , A13 = 1(2-1) = 1
A21 = -1(-4 -1) = 5 , A22 = 1(-4 -1) = -5 , A23 = 0
A31 = 1(0-1) = -1 , A32 = -1(0-2) = 2 and A33 = -1(1-2) = 1
So A-1 $\frac{1}{5}\left[\begin{array}{ccc}-4& 5& -1\\ 8& -5& 2\\ 1& 0& 1\end{array}\right]$
So
• 16
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https://blog.forexcycle.com/569/short-term-analysis-august-16-2007/ | # Short Term Analysis – August 16, 2007
USDCHF
USDCHF broke above 1.2163 (July 25 high). The pair is now in up trend. Further rise towards 1.2400 is expected in the next several days. Near term support is at the up trend line, and as long as the trend line support holds, up trend will continue.
USDJPY
USDJPY broke below 117.15 previous low and reached as low as 116.23 so far. Further fall towards 115.50 is still possible later today. Near term resistance is at the price channel, and as long as the channel resistance holds, down trend will continue.
GBPUSD
GBPUSD is in down trend. The fall from 2.0652 extended to as low as 1.9834, and further fall towards 1.9700 area is still possible in a couple of days. Near term resistance is at 1.9960, as long as this resistance holds, down trend will continue. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9017192125320435, "perplexity": 3116.4220423523207}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178358064.34/warc/CC-MAIN-20210227024823-20210227054823-00638.warc.gz"} |
https://forum.vbulletin.com/forum/vbulletin-5-connect/support-issues-questions/4438453-cleaning-up-database-errors-one-left-concurrent-optimize-or-alter-etc-is-running-update-timed-out-please-retry | # Announcement
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https://www.hpmuseum.org/forum/archive/index.php?thread-12529.html | # HP Forums
Full Version: (12C) Signum Function
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Signum Function is an odd mathematical function that extracts
the sign of a real number.
In mathematical expressions the sign function is often represented as sgn.
The Signum Function of a real number (x) is defined as follows:
sgn(x) = -1 if x < 0
sgn(x) = 0 if x = 0
sgn(x) = 1 if x > 0
For more detail on this topic
https://en.wikipedia.org/wiki/Sign_function
-------------------------------------------------
Example:
123 [R/S] display 1
-23.33 [R/S] display -1
0 [R/S] display 0
-------------------------------------------------
Program: for HP-12C
Code:
X=0 GTO 00 ENTER ENTER x √x ÷
Program: for HP-12C Platinum on RPN mode
Code:
X=0 GTO 000 ENTER x² √x ÷
Gamo
Same number of steps (on the HP-12C), working on full range:
Code:
01 ENTER 02 CHS 03 x<=y 04 CHS 05 x=0 06 n! 07 /
For HP-12 Platinum on ALG mode
Program:
Code:
[X=0] [GTO] 000 1 [x] [X<>Y] [x²] [√x] [÷] [LSTx] [=]
Gamo
(03-02-2019 05:47 AM)Gamo Wrote: [ -> ]For HP-12 Platinum on ALG mode
I do not have a 12C Platinum or an emulator, so I cannot check this, but on a TI calculator with AOS I'd simply type
[÷] [x²] [√x] [=]
Does this also work on the 12CP ?
Dieter
(03-02-2019 05:22 PM)Dieter Wrote: [ -> ]I do not have a 12C Platinum or an emulator, so I cannot check this, but on a TI calculator with AOS I'd simply type
[÷] [x²] [√x] [=]
Does this also work on the 12CP ?
Dieter
But... if the input is zero, you get an error instead of zero output.
Unique HP-12C Platinum in ALG mode
I'm not sure if TI Calculator with AOS got the [LSTx] function.
For 12CP in order to use [LSTx] it need to execute direct arithmetic first like
[+] [-] [x] [÷] but with [x²] or [√x] can not recall [LSTx] so then
I use 1 [x] [X<>Y] first so that I can recall [LSTx] later in program.
Gamo
(03-01-2019 06:29 AM)Gamo Wrote: [ -> ]
Code:
X=0 GTO 00 ENTER ENTER x √x ÷
This doesn't work for $$\left | x \right |\leqslant 10^{-50}$$ or $$\left | x \right | \geqslant 10^{50}$$ due to under- or overflow.
Obviously it works for numbers like -113 or 47.
But what happens with a number that uses all the 10 digits like 12.78974364?
When we square this number we get 163.5775424 which is rounded to 10 digits.
The exact value is 163.5775423769204496.
Taking the square root of the rounded value 163.5775424, why can we be sure that we get the original number?
If we received something off by 1 in the last digit, such as 12.78974363 or 12.78974365, we'd end up with 1.000000001 or 0.999999999 instead.
Any thoughts why this can't happen?
The reverse isn't true as we know: taking the square root of 3 gives 1.732050808.
But the square of this number is rounded to 3.000000001.
The exact value is 3.000000001493452864.
Kind regards
Thomas
(03-02-2019 08:57 PM)rprosperi Wrote: [ -> ]But... if the input is zero, you get an error instead of zero output.
Yes, sure, in a real program the first steps would be x=0? GTO 000.
(03-03-2019 02:31 AM)Gamo Wrote: [ -> ]Unique HP-12C Platinum in ALG mode
I'm not sure if TI Calculator with AOS got the [LSTx] function.
Of course not. But that's not my question. The point is that on a TI you don't need all this. There is no need to use LstX or a dummy multiplication. I just want to know whether the proposed key sequence (without 1 x multipliation and without LstX) also works on the 12CP or not.
Does it?
What happens if you press 123 [÷] [x²] [√x] [=] ?
Dieter
(03-03-2019 08:17 AM)Thomas Klemm Wrote: [ -> ]But what happens with a number that uses all the 10 digits like 12.78974364?
When we square this number we get 163.5775424 which is rounded to 10 digits ...
Taking the square root of the rounded value 163.5775424, why can we be sure that we get the original number?
If a number x had an uncertainty factor 1+ε, (x·(1+ε))² = x²·(1+2ε+ε²) ≈ x²·(1+2ε)
So, for squaring, uncertainly doubled (with at most ±½ ulp error).
Square root is just a reverse operation, uncertainly cut in half.
We would expect squaring, then square root, round-trip back to original number.
Program this in ALG mode for 12CP
[÷] [x²] [√x] [=]
123 [R/S] display 123
123 [CHS] [R/S] display 123
Above routine look like ABS function.
Gamo
(03-03-2019 02:39 PM)Gamo Wrote: [ -> ]Program this in ALG mode for 12CP
[÷] [x²] [√x] [=]
123 [R/S] display 123
123 [CHS] [R/S] display 123
Above routine look like ABS function.
Gamo
No, the above program returns -1.00 on a 12CP, as Dieter suspected.
SICNR, I had to try my first algebriac mode program on a 12CP...
Interesting UPDATE:
On the initial 12CP (before the (), Undo and Backspace were added) the above program returns -1.00, but on later models (including the Android emulator) returns 123 as Gamo reported.
Clearly a bug, I need to explore past bug reports. Intuitively, the initial behavior is correct and the later is not, though it seems unlikely such a bug has never been noticed and fixed...
(03-03-2019 01:15 PM)Albert Chan Wrote: [ -> ]If a number x had an uncertainty factor 1+ε, (x·(1+ε))² = x²·(1+2ε+ε²) ≈ x²·(1+2ε)
There's no "uncertainty" when it comes to rounding numbers.
Though this may be related it doesn't explain what's going on.
Cheers
Thomas
(03-03-2019 03:34 PM)rprosperi Wrote: [ -> ]On the initial 12CP (before the (), Undo and Backspace were added) the above program returns -1.00, but on later models (including the Android emulator) returns 123 as Gamo reported.
That's really weird. #-)
I wonder what happens in similar cases like
2 [+] [√x] [=]
or
5 [x] [LN] [x²] [=]
I'd expect 3,41 and 12,95 but obviously you never know...
Dieter
(03-03-2019 05:51 PM)Dieter Wrote: [ -> ]I wonder what happens in similar cases like
2 [+] [√x] [=]
or
5 [x] [LN] [x²] [=]
I'd expect 3,41 and 12,95 but obviously you never know...
That’s what I get on my TI 57, but on my 12c Prestige (and on the latest Platinums, I presume), arguments on the display cannot be reused after an operator. Thus, in order to get what you want the following sequences should be used:
2 [+] 2 [√x] [=] -> 3.414213562
5 [x] 5 [LN] [x²] [=] -> 12.95145197
IMHO, this is a feature, not a bug. Although the old behavior is apparently more convenient in some situations, I prefer this new one (or at least I would if I chose ALG, which I never will).
Gerson.
(03-03-2019 08:17 AM)Thomas Klemm Wrote: [ -> ]
(03-01-2019 06:29 AM)Gamo Wrote: [ -> ]
Code:
X=0 GTO 00 ENTER ENTER x √x ÷
This doesn't work for $$\left | x \right |\leqslant 10^{-50}$$ or $$\left | x \right | \geqslant 10^{50}$$ due to under- or overflow.
The RPN program in post #2 above completely avoids these shortcomings.
Gerson.
(03-03-2019 04:59 PM)Thomas Klemm Wrote: [ -> ]There's no "uncertainty" when it comes to rounding numbers.
Though this may be related it doesn't explain what's going on.
Turns out, there is nothing to explain. I found a counter-example ...
My post on square, following by square-root round-trip is wrong
Example, on HP-12C, x = Pi + 0.04 = 3.181592654
3.181592654^2 ≈ 10.1225318160, rounded-up-to 10.12253182
√10.12253182 ≈ 3.18159265463, rounded-up-to 3.181592655
Ratio of x / √(x²) = 0.9999999997 ≠ 1
(03-03-2019 05:51 PM)Dieter Wrote: [ -> ]I wonder what happens in similar cases like
2 [+] [√x] [=]
or
5 [x] [LN] [x²] [=]
I'd expect 3,41 and 12,95 but obviously you never know...
Your expectations are correct, IMHO.
Original 12CP: 3,41 & 12,95
Later 12CP: 1,41 & 2,59
I've not researched yet, but Gerson's summary "...arguments on the display cannot be reused after an operator..." seems a concise summary of the 'fixed' or at least updated, behavior. Denying re-use of the original argument may have been necessary (or at least easier) as a result of adding the UNDO feature in the 2nd and all later series of 12CP models.
One could argue either way which is 'right', since algebraic notation is notoriously ambiguous, though I must admit that this is a more interesting than normal situation.
@Gerson - of course the RPN solution works; they're always unambiguous.
(03-03-2019 07:49 PM)Albert Chan Wrote: [ -> ]Example, on HP-12C, x = Pi + 0.04 = 3.181592654
If we just look at the mantissa it appears that this only happens for values between $$\sqrt{10} \approx 3.16228$$ and $$5$$.
And within this interval it happens at about 18.37% of the cases.
Which is close to $$\frac{5 - \sqrt{10}}{10} \approx 0.18377$$.
Choosing a number at random leads to a wrong result in about 1 of 27 cases.
I don't think that we can neglect that.
Here's a table with some values $$x$$ having only 5 digits after the decimal point and $$\sqrt{x^2}$$ as it is calculated by the HP-12C:
Code:
3.16343 3.163429999 3.16466 3.164660001 3.17129 3.171289999 3.19029 3.190289999 3.19434 3.194340001 3.20766 3.207660001 3.22016 3.220160001 3.22092 3.220920001 3.22379 3.223789999 3.23338 3.233379999 3.23869 3.238690001 3.24384 3.243840001 3.25258 3.252580001 3.25807 3.258069999 3.26229 3.262289999 3.28479 3.284789999 3.28807 3.288069999 3.29319 3.293190001 3.29693 3.296929999 3.30756 3.307559999 3.32538 3.325379999 3.32808 3.328080001 3.34906 3.349059999 3.35962 3.359619999 3.36371 3.363709999 3.38234 3.382340001 3.38394 3.383939999 3.38838 3.388379999 3.41781 3.417810001 3.42121 3.421209999 3.42931 3.429310001 3.43142 3.431420001 3.44721 3.447209999 3.44906 3.449059999 3.45719 3.457190001 3.46108 3.461080001 3.47871 3.478709999 3.48116 3.481160001 3.48608 3.486080001 3.48643 3.486429999 3.48821 3.488209999 3.49429 3.494289999 3.49831 3.498310001 3.49921 3.499209999 3.50488 3.504879999 3.51834 3.518340001 3.53331 3.533310001 3.54069 3.540690001 3.54171 3.541709999 3.54388 3.543879999 3.54484 3.544840001 3.55221 3.552209999 3.55792 3.557920001 3.56512 3.565119999 3.57588 3.575879999 3.57734 3.577340001 3.57829 3.578289999 3.57866 3.578660001 3.58194 3.581939999 3.59334 3.593340001 3.59421 3.594209999 3.59556 3.595559999 3.60493 3.604929999 3.60834 3.608340001 3.61407 3.614069999 3.61743 3.617429999 3.61884 3.618840001 3.63366 3.633660001 3.63462 3.634619999 3.63771 3.637709999 3.65793 3.657929999 3.66531 3.665310001 3.67357 3.673569999 3.67557 3.675569999 3.67762 3.677619999 3.68834 3.688340001 3.69693 3.696929999 3.70616 3.706160001 3.71143 3.711429999 3.71466 3.714660001 3.72621 3.726209999 3.74243 3.742429999 3.75288 3.752879999 3.75638 3.756379999 3.75643 3.756429999 3.75938 3.759379999 3.77419 3.774190001 3.78007 3.780069999 3.79638 3.796379999 3.79731 3.797310001 3.80288 3.802879999 3.82866 3.828660001 3.84429 3.844289999 3.85679 3.856789999 3.87116 3.871160001 3.88507 3.885069999 3.89021 3.890209999 3.90788 3.907879999 3.91862 3.918619999 3.94979 3.949789999 3.95034 3.950340001 3.96016 3.960160001 3.96812 3.968119999 3.99571 3.995709999 4.00312 4.003119999 4.01279 4.012789999 4.01316 4.013160001 4.02188 4.021879999 4.07884 4.078840001 4.11312 4.113119999 4.15243 4.152429999 4.17866 4.178660001 4.19862 4.198619999 4.23857 4.238569999 4.24734 4.247340001 4.26734 4.267340001 4.28816 4.288160001 4.29112 4.291119999 4.30134 4.301340001 4.30566 4.305660001 4.33416 4.334160001 4.36738 4.367379999 4.38716 4.387160001 4.40307 4.403069999 4.44193 4.441929999 4.51507 4.515069999 4.51557 4.515569999 4.51793 4.517929999 4.57107 4.571069999 4.58657 4.586569999 4.64793 4.647929999 4.68393 4.683929999 4.72493 4.724929999 4.73393 4.733929999 4.77593 4.775929999 4.84307 4.843069999
Cheers
Thomas
(03-03-2019 11:27 PM)Thomas Klemm Wrote: [ -> ]If we just look at the mantissa it appears that this only happens for values between $$\sqrt{10} \approx 3.16228$$ and $$5$$.
This range can be explained by squaring errors: (x·(1+ε))² = x²·(1+2ε+ε²) ≈ x²·(1+2ε)
Assuming numbers in scientific notation, with mantissa = [1, 10), ulp = 1e-9
Max rel error of √(x²) ≈ ½ Max rel error of x² = ½ (½ ulp / mantissa(x²))
Max abs error of √(x²) ≈ ¼ ulp (mantissa(x) / mantissa(x²))
Round-trip errors occurs if √(x²) abs error ≥ ½ ulp
-> mantissa(x) between √10 and 5.0
-> Max abs error between 0.79 and 0.50 ulp
Edit: this also explained why (√x)² may have errors upto 3 ULP
Example: (√9.11)² = 9.110000003
Example program on ALG mode
Guass Sum (x² + x) ÷ 2
-------------------------------------
If program this way
[LSTx] [x²] + [LSTx] [÷] 2 [=]
Each [R/S] need to clear register to restart
Clear by pressing [CLx] [CLx]
100 [R/S] display 5050
If not clear 100 [R/S] display 12751300
---------------------------------------------
This routine no need to clear register but
Need the dummy (1 × X<>Y)
1 [×] [X<>Y] [x²] + [LSTx] [÷] 2 [=]
---------------------------------------------
Gamo
Pages: 1 2
Reference URL's
• HP Forums: https://www.hpmuseum.org/forum/index.php
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http://ncsostools.fis.unm.si/documentation/nceigmin | Documentation >
NCeigMin
description: [opt,decom_sohs,decom_S,base,SDP_data,Z,Zg,H,Hg,decom_err,Y] = NCeigMin(f,S,d,params) computes the lower bound for the minimum eigenvalue of f on all matrices A = D_S, where S contains polynomials, i.e. lower bound for inf lambda_min (f(A)) s.t. g(A)\succeq 0 for all g in SIt solves: min H ... hankel (moment) matrix H(1) = 1 H >= 0 H^g >= 0 (H_g)_p,q = L(p^*gq), for all g in Swhere H is of order |W_{d/2}| and H_g is of order |W_{d/2-deg(g)/2}| and d is inputThis is dual to: sup eps s.t. f-eps = SOHS + \sum_{g\in S}\sum_i h_j^*gh_j arguments: f is an NCpoly representing a polynomialS is a set of nc polynomails defining D_Sd is a starting degree for the hierarchy (even number)With params.precision we can set the smallest value that is considered to be nonzero in numerical calculations; if the command is called without it, we assume the precision set with the command NCsetPrecision or the value set in NCparam.m.params.messages is used to optionally turn on (1) and off (0) verbose output; default value is 1 (on).params.solver sets the solver to be used for SDP and overrides the value set in the global option file NCparam.m. (currently SeDuMi, SDPA-M or SDPT3 are supported) params.eps sets the desired accuracy iy you are using SeDuMi as SDP solver. Setting params.eps=0 lets SeDuMi run as long as it can make progress.params.justSDP_data == 1 means that the program ends when the SDP_data is prepared and nothing else is computed. It is optional; the default value is 0.params.decomposition == 0 means that no SOHS decomposition over the module will actually be computed. It is optional; the default value is 1. output: opt ... optimal value of the SDPdecom_sohs ... sohs part of the sohs decomposition over the module M_{S,d}decom_S ... weights of polynomials gin Sbase ... is a list of monomials which appear in the SOHS decomposition over SSDP_data ... is a structure holding all the data used in SDP solverZ ... dual solution, that represent sohsZg.... dual solution that contains wightsH ... Hankel matrixHg ... shifted Hankel matrices for g in Sdecom_err ... how much sohs decomposition differs from f possible usage: NCeigMin(f,S,d),NCeigMin(f,S,d,params) | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8409243822097778, "perplexity": 5890.417248518649}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-09/segments/1518891814101.27/warc/CC-MAIN-20180222101209-20180222121209-00182.warc.gz"} |
https://www.knowpia.com/knowpedia/Longitude | BREAKING NEWS
Longitude
## Summary
A graticule on the Earth as a sphere or an ellipsoid. The lines from pole to pole are lines of constant longitude, or meridians. The circles parallel to the Equator are circles of constant latitude, or parallels. The graticule shows the latitude and longitude of points on the surface. In this example, meridians are spaced at 6° intervals and parallels at 4° intervals.
Longitude (/ˈlɒnɪtjd/, AU and UK also /ˈlɒŋɡɪ-/),[1][2] is a geographic coordinate that specifies the eastwest position of a point on the Earth's surface, or the surface of a celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians (lines running from pole to pole) connect points with the same longitude. The prime meridian, which passes near the Royal Observatory, Greenwich, England, is defined as 0° longitude by convention. Positive longitudes are east of the prime meridian, and negative ones are west.
Because of the earth's rotation, there is a close connection between longitude and time. Local time (for example from the position of the sun) varies with longitude, a difference of 15° longitude corresponding to a one-hour difference in local time. Comparing local time to an absolute measure of time allows longitude to be determined. Depending on the era, the absolute time might be obtained from a celestial event visible from both locations, such as a lunar eclipse, or from a time signal transmitted by telegraph or wireless. The principle is straightforward, but in practice finding a reliable method of determining longitude took centuries and required the effort of some of the greatest scientific minds.
A location's northsouth position along a meridian is given by its latitude, which is approximately the angle between the local vertical and the equatorial plane.
Longitude is generally given using the geometrical or astronomical vertical. This can differ slightly from the gravitational vertical because of small variations in Earth's gravitational field.
## History
The concept of longitude was first developed by ancient Greek astronomers. Hipparchus (2nd century BCE) used a coordinate system that assumed a spherical earth, and divided it into 360° as we still do today. His prime meridian passed through Alexandria.[3]:31 He also proposed a method of determining longitude by comparing the local time of a lunar eclipse at two different places, thus demonstrating an understanding of the relationship between longitude and time.[3]:11.[4] Claudius Ptolemy (2nd century CE) developed a mapping system using curved parallels that reduced distortion. He also collected data for many locations, from Britain to the Middle East. He used a prime meridian through the Canary Islands, so that all longitude values would be positive. While Ptolemy's system was sound, the data he used were often poor, leading to a gross over-estimate (by about 70%) of the length of the Mediterranean.[5][6]:551–553[7]
After the fall of the Roman Empire, interest in geography greatly declined in Europe.[8]:65 Hindu and Muslim astronomers continued to develop these ideas, adding many new locations and often improving on Ptolemy's data.[9][10] For example al-Battānī used simultaneous observations of two lunar eclipses to determine the difference in longitude between Antakya and Raqqa with an error of less than 1°. This is considered to be the best that can be achieved with the methods then available - observation of the eclipse with the naked eye, and determination of local time using an astrolabe to measure the altitude of a suitable "clock star".[11][12]
In the later Middle Ages, interest in geography revived in the west, as travel increased, and Arab scholarship began to be known through contact with Spain and North Africa. In the 12th Century, astronomical tables were prepared for a number of European cities, based on the work of al-Zarqālī in Toledo. The lunar eclipse of September 12, 1178 was used to establish the longitude differences between Toledo, Marseilles, and Hereford.[13]:85
Christopher Columbus made two attempts to use lunar eclipses to discover his longitude, the first in Saona Island, on 14 September 1494 (second voyage), and the second in Jamaica on 29 February 1504 (fourth voyage). It is assumed that he used astronomical tables for reference. His determinations of longitude showed large errors of 13 and 38° W respectively.[14] Randles (1985) documents longitude measurement by the Portuguese and Spanish between 1514 and 1627 both in the Americas and Asia. Errors ranged from 2-25°.[15]
The telescope was invented in the early 17th-century. Initially an observation device, developments over the next half century transformed it into an accurate measurement tool.[16][17] The pendulum clock was patented by Christiaan Huygens in 1657[18] and gave an increase in accuracy of about 30 fold over previous mechanical clocks.[19] These two inventions would revolutionize observational astronomy and cartography.[20]
The main methods for determining longitude are listed below. With one exception (magnetic declination) they all depend on a common principle, which was to determine an absolute time from an event or measurement and to compare the corresponding local time at two different locations.
• Lunar distances. In its orbit around the earth, the moon moves relative to the stars at a rate of just over 0.5°/hour. The angle between the moon and a suitable star is measured with a sextant, and (after consultation with tables and lengthy calculations) gives a value for absolute time.
• Satellites of Jupiter. Galileo proposed that with sufficiently accurate knowledge of the orbits of the satellites, their positions could provide a measure of absolute time. The method requires a telescope, as the moons are not visible to the naked eye.
• Appulses, occultations, and eclipses. An appulse is the least apparent distance between two objects (the moon a star or a planet), an occultation occurs when a star or planet passes behind the moon — essentially a type of eclipse. Lunar eclipses continued to be used. The times of any of these events can be used as the measure of absolute time.
• Chronometers. A clock is set to the local time of a starting point whose longitude is known, and the longitude of any other place can be determined by comparing its local time with the clock time.
• Magnetic declination. A compass needle does not in general point exactly north. The variation from true north varies with location, and it was suggested that this could provide a basis for determination of longitude.
With the exception of magnetic declination, all proved practicable methods. Developments on land and sea, however, were very different.
On land, the period from the development of telescopes and pendulum clocks until the mid 18th-Century saw a steady increase in the number of places whose longitude had been determined with reasonable accuracy, often with errors of less than a degree, and nearly always within 2-3°. By the 1720s errors were consistently less than 1°.[21] At sea during the same period, the situation was very different. Two problems proved intractable. The first was the need of a navigator for immediate results. The second was the marine environment. Making accurate observations in an ocean swell is much harder than on land, and pendulum clocks do not work well in these conditions.
In response to the problems of navigation, a number of European maritime powers offered prizes for a method to determine longitude at sea. The best-known of these is the Longitude Act passed by the British parliament in 1714.[22]:8 It offered two levels of rewards, for solutions within 1° and 0.5°. Rewards were given for two solutions: lunar distances, made practicable by the tables of Tobias Mayer[23] developed into an nautical almanac by the Astronomer Royal Neville Maskelyne; and for the chronometers developed by the Yorkshire carpenter and clock-maker John Harrison. Harrison built five chronometers over more than three decades. However, he was not awarded the prize by the Longitude Board and was forced to fight for his reward, finally receiving payment in 1773, after the intervention of parliament[22]:26. It was some while before either method became widely used in navigation. In the early years, chronometers were very expensive, and the calculations required for lunar distances were still complex and time-consuming. Lunar distances came into general use after 1790.[24] Chronometers had the advantages that both the observations and the calculations were simpler, and as they became cheaper in the early 19th-Century they started to replace lunars, which were seldom used after 1850.[25]
The first working telegraphs were established in Britain by Wheatstone and Cooke in 1839, and in the US by Morse in 1844. It was quickly realised that the telegraph could be used to transmit a time signal for longitude determination.[26] The method was soon in practical use for longitude determination, especially in North America, and over longer and longer distances as the telegraph network expanded, including western Europe with the completion of transatlantic cables. The US Coast Survey was particularly active in this development, and not just in the United States. The Survey established chains of mapped locations through Central and South America, and the West Indies, and as far as Japan and China in the years 1874–90. This contributed greatly to the accurate mapping of these areas.[27][28]
While mariners benefited from the accurate charts, they could not receive telegraph signals while under way, and so could not use the method for navigation. This changed when wireless telegraphy became available in the early 20th-Century.[29] Wireless time signals for the use of ships were transmitted from Halifax, Nova Scotia, starting in 1907[30] and from the Eiffel Tower in Paris from 1910.[31] These signals allowed navigators to check and adjust their chronometers on a frequent basis.[32]
Radio navigation systems came into general use after World War II. The systems all depended on transmissions from fixed navigational beacons. A ship-board receiver calculated the vessel's position from these transmissions.[33] They allowed accurate navigation when poor visibility prevented astronomical observations, and became the established method for commercial shipping until replaced by GPS in the early 1990s.
## Noting and calculating longitude
Longitude is given as an angular measurement ranging from 0° at the Prime Meridian to +180° eastward and −180° westward. The Greek letter λ (lambda),[34][35] is used to denote the location of a place on Earth east or west of the Prime Meridian.
Each degree of longitude is sub-divided into 60 minutes, each of which is divided into 60 seconds. A longitude is thus specified in sexagesimal notation as 23° 27′ 30″ E. For higher precision, the seconds are specified with a decimal fraction. An alternative representation uses degrees and minutes, where parts of a minute are expressed in decimal notation with a fraction, thus: 23° 27.5′ E. Degrees may also be expressed as a decimal fraction: 23.45833° E. For calculations, the angular measure may be converted to radians, so longitude may also be expressed in this manner as a signed fraction of π (pi), or an unsigned fraction of 2π.
For calculations, the West/East suffix is replaced by a negative sign in the western hemisphere. The international standard convention (ISO 6709)—that East is positive—is consistent with a right-handed Cartesian coordinate system, with the North Pole up. A specific longitude may then be combined with a specific latitude (positive in the northern hemisphere) to give a precise position on the Earth's surface. Confusingly, the convention of negative for East is also sometimes seen, most commonly in the United States; the Earth System Research Laboratory used it on an older version of one of their pages, in order "to make coordinate entry less awkward" for applications confined to the Western Hemisphere. They have since shifted to the standard approach.[36]
There is no other physical principle determining longitude directly but with time. Longitude at a point may be determined by calculating the time difference between that at its location and Coordinated Universal Time (UTC). Since there are 24 hours in a day and 360 degrees in a circle, the sun moves across the sky at a rate of 15 degrees per hour (360° ÷ 24 hours = 15° per hour). So if the time zone a person is in is three hours ahead of UTC then that person is near 45° longitude (3 hours × 15° per hour = 45°). The word near is used because the point might not be at the center of the time zone; also the time zones are defined politically, so their centers and boundaries often do not lie on meridians at multiples of 15°. In order to perform this calculation, however, a person needs to have a chronometer (watch) set to UTC and needs to determine local time by solar or astronomical observation. The details are more complex than described here: see the articles on Universal Time and on the equation of time for more details.
### Singularity and discontinuity of longitude
Note that the longitude is singular at the Poles and calculations that are sufficiently accurate for other positions may be inaccurate at or near the Poles. Also the discontinuity at the ±180° meridian must be handled with care in calculations. An example is a calculation of east displacement by subtracting two longitudes, which gives the wrong answer if the two positions are on either side of this meridian. To avoid these complexities, consider replacing latitude and longitude with another horizontal position representation in calculation.
## Plate movement and longitude
The Earth's tectonic plates move relative to one another in different directions at speeds on the order of 50 to 100 mm (2.0 to 3.9 in) per year.[37] So points on the Earth's surface on different plates are always in motion relative to one another. For example, the longitudinal difference between a point on the Equator in Uganda, on the African Plate, and a point on the Equator in Ecuador, on the South American Plate, is increasing by about 0.0014 arcseconds per year. These tectonic movements likewise affect latitude.
If a global reference frame (such as WGS84, for example) is used, the longitude of a place on the surface will change from year to year. To minimize this change, when dealing just with points on a single plate, a different reference frame can be used, whose coordinates are fixed to a particular plate, such as "NAD83" for North America or "ETRS89" for Europe.
## Length of a degree of longitude
The length of a degree of longitude (east–west distance) depends only on the radius of a circle of latitude. For a sphere of radius a that radius at latitude φ is a cos φ, and the length of a one-degree (or π/180 radian) arc along a circle of latitude is
${\displaystyle \Delta _{\rm {long}}^{1}={\frac {\pi }{180^{\circ }}}a\cos \phi }$
φ Δ1
lat
Δ1
long
110.574 km 111.320 km
15° 110.649 km 107.551 km
30° 110.852 km 96.486 km
45° 111.133 km 78.847 km
60° 111.412 km 55.800 km
75° 111.618 km 28.902 km
90° 111.694 km 0.000 km
Length of one degree (black), minute (blue) and second (red) of latitude and longitude in metric (upper half) and imperial units (lower half) at a given latitude (vertical axis) in WGS84. For example, the green arrows show that Donetsk (green circle) at 48°N has a Δlong of 74.63 km/° (1.244 km/min, 20.73 m/sec etc) and a Δlat of 111.2 km/° (1.853 km/min, 30.89 m/sec etc).
When the Earth is modelled by an ellipsoid this arc length becomes[38][39]
${\displaystyle \Delta _{\rm {long}}^{1}={\frac {\pi a\cos \phi }{180^{\circ }{\sqrt {1-e^{2}\sin ^{2}\phi }}}}}$
where e, the eccentricity of the ellipsoid, is related to the major and minor axes (the equatorial and polar radii respectively) by
${\displaystyle e^{2}={\frac {a^{2}-b^{2}}{a^{2}}}}$
An alternative formula is
${\displaystyle \Delta _{\rm {long}}^{1}={\frac {\pi }{180^{\circ }}}a\cos \beta \quad {\mbox{where }}\tan \beta ={\frac {b}{a}}\tan \phi }$; here ${\displaystyle \beta }$ is the so-called parametric or reduced latitude.
Cos φ decreases from 1 at the equator to 0 at the poles, which measures how circles of latitude shrink from the equator to a point at the pole, so the length of a degree of longitude decreases likewise. This contrasts with the small (1%) increase in the length of a degree of latitude (north–south distance), equator to pole. The table shows both for the WGS84 ellipsoid with a = 6378137.0 m and b = 6356752.3142 m. Note that the distance between two points 1 degree apart on the same circle of latitude, measured along that circle of latitude, is slightly more than the shortest (geodesic) distance between those points (unless on the equator, where these are equal); the difference is less than 0.6 m (2 ft).
A geographical mile is defined to be the length of one minute of arc along the equator (one equatorial minute of longitude), therefore a degree of longitude along the equator is exactly 60 geographical miles or 111.3 kilometers, as there are 60 minutes in a degree. The length of 1 minute of longitude along the equator is 1 geographical mile or 1.855 km or 1.153 miles, while the length of 1 second of it is 0.016 geographical mile or 30.916 m or 101.43 feet.
## Longitude on bodies other than Earth
Planetary coordinate systems are defined relative to their mean axis of rotation and various definitions of longitude depending on the body. The longitude systems of most of those bodies with observable rigid surfaces have been defined by references to a surface feature such as a crater. The north pole is that pole of rotation that lies on the north side of the invariable plane of the solar system (near the ecliptic). The location of the prime meridian as well as the position of the body's north pole on the celestial sphere may vary with time due to precession of the axis of rotation of the planet (or satellite). If the position angle of the body's prime meridian increases with time, the body has a direct (or prograde) rotation; otherwise the rotation is said to be retrograde.
In the absence of other information, the axis of rotation is assumed to be normal to the mean orbital plane; Mercury and most of the satellites are in this category. For many of the satellites, it is assumed that the rotation rate is equal to the mean orbital period. In the case of the giant planets, since their surface features are constantly changing and moving at various rates, the rotation of their magnetic fields is used as a reference instead. In the case of the Sun, even this criterion fails (because its magnetosphere is very complex and does not really rotate in a steady fashion), and an agreed-upon value for the rotation of its equator is used instead.
For planetographic longitude, west longitudes (i.e., longitudes measured positively to the west) are used when the rotation is prograde, and east longitudes (i.e., longitudes measured positively to the east) when the rotation is retrograde. In simpler terms, imagine a distant, non-orbiting observer viewing a planet as it rotates. Also suppose that this observer is within the plane of the planet's equator. A point on the Equator that passes directly in front of this observer later in time has a higher planetographic longitude than a point that did so earlier in time.
However, planetocentric longitude is always measured positively to the east, regardless of which way the planet rotates. East is defined as the counter-clockwise direction around the planet, as seen from above its north pole, and the north pole is whichever pole more closely aligns with the Earth's north pole. Longitudes traditionally have been written using "E" or "W" instead of "+" or "−" to indicate this polarity. For example, −91°, 91°W, +269° and 269°E all mean the same thing.
The reference surfaces for some planets (such as Earth and Mars) are ellipsoids of revolution for which the equatorial radius is larger than the polar radius, such that they are oblate spheroids. Smaller bodies (Io, Mimas, etc.) tend to be better approximated by triaxial ellipsoids; however, triaxial ellipsoids would render many computations more complicated, especially those related to map projections. Many projections would lose their elegant and popular properties. For this reason spherical reference surfaces are frequently used in mapping programs.
The modern standard for maps of Mars (since about 2002) is to use planetocentric coordinates. Guided by the works of historical astronomers, Merton E. Davies established the meridian of Mars at Airy-0 crater.[40][41] For Mercury, the only other planet with a solid surface visible from Earth, a thermocentric coordinate is used: the prime meridian runs through the point on the equator where the planet is hottest (due to the planet's rotation and orbit, the sun briefly retrogrades at noon at this point during perihelion, giving it more sun). By convention, this meridian is defined as exactly twenty degrees of longitude east of Hun Kal.[42][43][44]
Tidally-locked bodies have a natural reference longitude passing through the point nearest to their parent body: 0° the center of the primary-facing hemisphere, 90° the center of the leading hemisphere, 180° the center of the anti-primary hemisphere, and 270° the center of the trailing hemisphere.[45] However, libration due to non-circular orbits or axial tilts causes this point to move around any fixed point on the celestial body like an analemma.
## References
1. ^ "Definition of LONGITUDE". www.merriam-webster.com. Merriam-Webster. Retrieved 14 March 2018.
2. ^ Oxford English Dictionary
3. ^ a b Dicks, D.R. (1953). Hipparchus : a critical edition of the extant material for his life and works (PhD). Birkbeck College, University of London.
4. ^ Hoffman, Susanne M. (2016). "How time served to measure the geographical position since Hellenism". In Arias, Elisa Felicitas; Combrinck, Ludwig; Gabor, Pavel; Hohenkerk, Catherine; Seidelmann, P.Kenneth (eds.). The Science of Time. Astrophysics and Space Science Proceedings. 50. Springer International. pp. 25–36. doi:10.1007/978-3-319-59909-0_4. ISBN 978-3-319-59908-3.
5. ^ Mittenhuber, Florian (2010). "The Tradition of Texts and Maps in Ptolemy's Geography". In Jones, Alexander (ed.). Ptolemy in Perspective: Use and Criticism of his Work from Antiquity to the Nineteenth Century. Archimedes. 23. Dordrecht: Springer. pp. 95-119. doi:10.1007/978-90-481-2788-7_4. ISBN 978-90-481-2787-0.
6. ^ Bunbury, E.H. (1879). A History of Ancient Geography. 2. London: John Murray.
7. ^ Shcheglov, Dmitry A. (2016). "The Error in Longitude in Ptolemy's Geography Revisited". The Cartographic Journal. 53 (1): 3–14. doi:10.1179/1743277414Y.0000000098. S2CID 129864284.
8. ^ Wright, John Kirtland (1925). The geographical lore of the time of the Crusades: A study in the history of medieval science and tradition in Western Europe. New York: American geographical society.
9. ^ Ragep, F.Jamil (2010). "Islamic reactions to Ptolemy's imprecisions". In Jones, A. (ed.). Ptolemy in Perspective. Archimedes. 23. Dordrecht: Springer. doi:10.1007/978-90-481-2788-7. ISBN 978-90-481-2788-7.
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11. ^ Said, S.S.; Stevenson, F.R. (1997). "Solar and Lunar Eclipse Measurements by Medieval Muslim Astronomers, II: Observations". Journal for the History of Astronomy. 28 (1): 29–48. Bibcode:1997JHA....28...29S. doi:10.1177/002182869702800103. S2CID 117100760.
12. ^ Steele, John Michael (1998). Observations and predictions of eclipse times by astronomers in the pre-telescopic period (PhD). University of Durham (United Kingdom).
13. ^ Wright, John Kirtland (1923). "Notes on the Knowledge of Latitudes and Longitudes in the Middle Ages". Isis. 5 (1). Bibcode:1922nkll.book.....W.
14. ^ Pickering, Keith (1996). "Columbus's Method of Determining Longitude: An Analytical View". The Journal of Navigation. 49 (1): 96–111. Bibcode:1996JNav...49...95P. doi:10.1017/S037346330001314X.
15. ^ Randles, W.G.L. (1985). "Portuguese and Spanish attempts to measure longitude in the 16th century". Vistas in Astronomy. 28 (1): 235–241. Bibcode:1985VA.....28..235R. doi:10.1016/0083-6656(85)90031-5.
16. ^ Pannekoek, Anton (1989). A history of astronomy. Courier Corporation. pp. 259–276.
17. ^ Van Helden, Albert (1974). "The Telescope in the Seventeenth Century". Isis. 65 (1): 38–58. doi:10.1086/351216. JSTOR 228880.
18. ^ Grimbergen, Kees (2004). Fletcher, Karen (ed.). Huygens and the advancement of time measurements. Titan - From Discovery to Encounter. Titan - from Discovery to Encounter. 1278. ESTEC, Noordwijk, Netherlands: ESA Publications Division. pp. 91–102. Bibcode:2004ESASP1278...91G. ISBN 92-9092-997-9.
19. ^ Blumenthal, Aaron S.; Nosonovsky, Michael (2020). "Friction and Dynamics of Verge and Foliot: How the Invention of the Pendulum Made Clocks Much More Accurate". Applied Mechanics. 1 (2): 111–122. doi:10.3390/applmech1020008.
20. ^ Olmsted, J.W. (1960). "The Voyage of Jean Richer to Acadia in 1670: A Study in the Relations of Science and Navigation under Colbert". Proceedings of the American Philosophical Society. 104 (6): 612–634. JSTOR 985537.
21. ^ See, for example, Port Royal, Jamaica: Halley, Edmond (1722). "Observations on the Eclipse of the Moon, June 18, 1722. and the Longitude of Port Royal in Jamaica". Philosophical Transactions. 32 (370–380): 235–236.; Buenos Aires: Halley, Edm. (1722). "The Longitude of Buenos Aires, Determin'd from an Observation Made There by Père Feuillée". Philosophical Transactions. 32 (370–380): 2–4.Santa Catarina, Brazil: Legge, Edward; Atwell, Joseph (1743). "Extract of a letter from the Honble Edward Legge, Esq; F. R. S. Captain of his Majesty's ship the Severn, containing an observation of the eclipse of the moon, Dec. 21. 1740. at the Island of St. Catharine on the Coast of Brasil". Philosophical Transactions. 42 (462): 18–19.
22. ^ a b Siegel, Jonathan R. (2009). "Law and Longitude". Tulane Law Review. 84: 1–66.
23. ^ Forbes, Eric Gray (2006). "Tobias Mayer's lunar tables". Annals of Science. 22 (2): 105–116. doi:10.1080/00033796600203075. ISSN 0003-3790.
24. ^ Wess, Jane (2015). "Navigation and Mathematics: A Match Made in the Heavens?". In Dunn, Richard; Higgitt, Rebekah (eds.). Navigational Enterprises in Europe and its Empires, 1730-1850. London: Palgrave Macmillan UK. pp. 201–222. doi:10.1057/9781137520647_11. ISBN 978-1-349-56744-7.
25. ^ Littlehales, G.W. (1909). "The Decline of the Lunar Distance for the Determination of the Time and Longitude at". Bulletin of the American Geographical Society. 41 (2): 83–86. doi:10.2307/200792. JSTOR 200792.
26. ^ Walker, Sears C (1850). "Report on the experience of the Coast Survey in regard to telegraph operations, for determination of longitude &c". American Journal of Science and Arts. 10 (28): 151–160.
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28. ^ Green, Francis Mathews; Davis, Charles Henry; Norris, John Alexander (1883). Telegraphic Determination of Longitudes in Japan, China, and the East Indies: Embracing the Meridians of Yokohama, Nagasaki, Wladiwostok, Shanghai, Amoy, Hong-Kong, Manila, Cape St. James, Singapore, Batavia, and Madras, with the Latitude of the Several Stations. Washington: US Hydrographic Office.
29. ^ Munro, John (1902). "Time-Signals by Wireless Telegraphy". Nature. 66 (1713): 416. Bibcode:1902Natur..66..416M. doi:10.1038/066416d0. ISSN 0028-0836. S2CID 4021629.
30. ^ Hutchinson, D.L. (1908). "Wireless Time Signals from the St. John Observatory of the Canadian Meteorological Service". Proceedings and Transactions of the Royal Society of Canada. Ser. 3 Vol. 2: 153–154.
31. ^ Lockyer, William J. S. (1913). "International Time and Weather Radio-Telegraphic Signals". Nature. 91 (2263): 33–36. Bibcode:1913Natur..91...33L. doi:10.1038/091033b0. ISSN 0028-0836. S2CID 3977506.
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39. ^ Rapp, Richard H. (April 1991). "Chapter 3: Properties of the Ellipsoid". Geometric Geodesy Part I. Columbus, Ohio.: Department of Geodetic Science and Surveying, Ohio State University. hdl:1811/24333. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 5, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6961091160774231, "perplexity": 2587.360558042287}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-04/segments/1610704821253.82/warc/CC-MAIN-20210127055122-20210127085122-00598.warc.gz"} |
http://www.let.rug.nl/~gosse/termpedia2/termpedia.php?language=dutch_general&density=7&link_color=000000&termpedia_system=perl_db&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FCrystal_system | # Crystal system
The diamond crystal structure belongs to the face-centered cubic lattice, with a repeated two-atom pattern.
In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals. Informally, two crystals are in the same crystal system if they have similar symmetries, although there are many exceptions to this.
Crystal systems, crystal families and lattice systems are similar but slightly different, and there is widespread confusion between them: in particular the trigonal crystal system is often confused with the rhombohedral lattice system, and the term "crystal system" is sometimes used to mean "lattice system" or "crystal family".
Space groups and crystals are divided into seven crystal systems according to their point groups, and into seven lattice systems according to their Bravais lattices. Five of the crystal systems are essentially the same as five of the lattice systems, but the hexagonal and trigonal crystal systems differ from the hexagonal and rhombohedral lattice systems. The six crystal families are formed by combining the hexagonal and trigonal crystal systems into one hexagonal family, in order to eliminate this confusion.
## Overview
Hexagonal hanksite crystal, with threefold c-axis symmetry
A lattice system is a class of lattices with the same set of lattice point groups, which are subgroups of the arithmetic crystal classes. The 14 Bravais lattices are grouped into seven lattice systems: triclinic, monoclinic, orthorhombic, tetragonal, rhombohedral, hexagonal, and cubic.
In a crystal system, a set of point groups and their corresponding space groups are assigned to a lattice system. Of the 32 point groups that exist in three dimensions, most are assigned to only one lattice system, in which case both the crystal and lattice systems have the same name. However, five point groups are assigned to two lattice systems, rhombohedral and hexagonal, because both exhibit threefold rotational symmetry. These point groups are assigned to the trigonal crystal system. In total there are seven crystal systems: triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, and cubic.
A crystal family is determined by lattices and point groups. It is formed by combining crystal systems which have space groups assigned to a common lattice system. In three dimensions, the crystal families and systems are identical, except the hexagonal and trigonal crystal systems, which are combined into one hexagonal crystal family. In total there are six crystal families: triclinic, monoclinic, orthorhombic, tetragonal, hexagonal, and cubic.
Spaces with less than three dimensions have the same number of crystal systems, crystal families and lattice systems. In one-dimensional space, there is one crystal system. In 2D space, there are four crystal systems: oblique, rectangular, square, and hexagonal.
The relation between three-dimensional crystal families, crystal systems and lattice systems is shown in the following table:
Crystal family (6) Crystal system (7) Required symmetries of point group Point groups Space groups Bravais lattices Lattice system
Triclinic None 2 2 1 Triclinic
monoclinic 1 twofold axis of rotation or 1 mirror plane 3 13 2 monoclinic
Orthorhombic 3 twofold axes of rotation or 1 twofold axis of rotation and 2 mirror planes 3 59 4 Orthorhombic
Tetragonal 1 fourfold axis of rotation 7 68 2 Tetragonal
Hexagonal Trigonal 1 threefold axis of rotation 5 7 1 Rhombohedral
18 1 Hexagonal
Hexagonal 1 sixfold axis of rotation 7 27
Cubic 3 fourfold axes of rotation 5 36 3 Cubic
6 7 Total 32 230 14 7
Note: there is no "trigonal" lattice system. To avoid confusion of terminology, the term "trigonal lattice" is not used.
## Crystal classes
The 7 crystal systems consist of 32 crystal classes (corresponding to the 32 crystallographic point groups) as shown in the following table:
Crystal family Crystal system Point group / Crystal class Schönflies Hermann–Mauguin Orbifold Coxeter Point symmetry Order Abstract group
triclinic pedial C1 1 11 [ ]+ enantiomorphic polar 1 trivial ${\displaystyle \mathbb {Z} _{1}}$
pinacoidal Ci (S2) 1 1x [2,1+] centrosymmetric 2 cyclic ${\displaystyle \mathbb {Z} _{2}}$
monoclinic sphenoidal C2 2 22 [2,2]+ enantiomorphic polar 2 cyclic ${\displaystyle \mathbb {Z} _{2}}$
domatic Cs (C1h) m *11 [ ] polar 2 cyclic ${\displaystyle \mathbb {Z} _{2}}$
prismatic C2h 2/m 2* [2,2+] centrosymmetric 4 Klein four ${\displaystyle \mathbb {V} =\mathbb {Z} _{2}\times \mathbb {Z} _{2}}$
orthorhombic rhombic-disphenoidal D2 (V) 222 222 [2,2]+ enantiomorphic 4 Klein four ${\displaystyle \mathbb {V} =\mathbb {Z} _{2}\times \mathbb {Z} _{2}}$
rhombic-pyramidal C2v mm2 *22 [2] polar 4 Klein four ${\displaystyle \mathbb {V} =\mathbb {Z} _{2}\times \mathbb {Z} _{2}}$
rhombic-dipyramidal D2h (Vh) mmm *222 [2,2] centrosymmetric 8 ${\displaystyle \mathbb {V} \times \mathbb {Z} _{2}}$
tetragonal tetragonal-pyramidal C4 4 44 [4]+ enantiomorphic polar 4 cyclic ${\displaystyle \mathbb {Z} _{4}}$
tetragonal-disphenoidal S4 4 2x [2+,2] non-centrosymmetric 4 cyclic ${\displaystyle \mathbb {Z} _{4}}$
tetragonal-dipyramidal C4h 4/m 4* [2,4+] centrosymmetric 8 ${\displaystyle \mathbb {Z} _{4}\times \mathbb {Z} _{2}}$
tetragonal-trapezohedral D4 422 422 [2,4]+ enantiomorphic 8 dihedral ${\displaystyle \mathbb {D} _{8}=\mathbb {Z} _{4}\rtimes \mathbb {Z} _{2}}$
ditetragonal-pyramidal C4v 4mm *44 [4] polar 8 dihedral ${\displaystyle \mathbb {D} _{8}=\mathbb {Z} _{4}\rtimes \mathbb {Z} _{2}}$
tetragonal-scalenohedral D2d (Vd) 42m or 4m2 2*2 [2+,4] non-centrosymmetric 8 dihedral ${\displaystyle \mathbb {D} _{8}=\mathbb {Z} _{4}\rtimes \mathbb {Z} _{2}}$
ditetragonal-dipyramidal D4h 4/mmm *422 [2,4] centrosymmetric 16 ${\displaystyle \mathbb {D} _{8}\times \mathbb {Z} _{2}}$
hexagonal trigonal trigonal-pyramidal C3 3 33 [3]+ enantiomorphic polar 3 cyclic ${\displaystyle \mathbb {Z} _{3}}$
rhombohedral C3i (S6) 3 3x [2+,3+] centrosymmetric 6 cyclic ${\displaystyle \mathbb {Z} _{6}=\mathbb {Z} _{3}\times \mathbb {Z} _{2}}$
trigonal-trapezohedral D3 32 or 321 or 312 322 [3,2]+ enantiomorphic 6 dihedral ${\displaystyle \mathbb {D} _{6}=\mathbb {Z} _{3}\rtimes \mathbb {Z} _{2}}$
ditrigonal-pyramidal C3v 3m or 3m1 or 31m *33 [3] polar 6 dihedral ${\displaystyle \mathbb {D} _{6}=\mathbb {Z} _{3}\rtimes \mathbb {Z} _{2}}$
ditrigonal-scalenohedral D3d 3m or 3m1 or 31m 2*3 [2+,6] centrosymmetric 12 dihedral ${\displaystyle \mathbb {D} _{12}=\mathbb {Z} _{6}\rtimes \mathbb {Z} _{2}}$
hexagonal hexagonal-pyramidal C6 6 66 [6]+ enantiomorphic polar 6 cyclic ${\displaystyle \mathbb {Z} _{6}=\mathbb {Z} _{3}\times \mathbb {Z} _{2}}$
trigonal-dipyramidal C3h 6 3* [2,3+] non-centrosymmetric 6 cyclic ${\displaystyle \mathbb {Z} _{6}=\mathbb {Z} _{3}\times \mathbb {Z} _{2}}$
hexagonal-dipyramidal C6h 6/m 6* [2,6+] centrosymmetric 12 ${\displaystyle \mathbb {Z} _{6}\times \mathbb {Z} _{2}}$
hexagonal-trapezohedral D6 622 622 [2,6]+ enantiomorphic 12 dihedral ${\displaystyle \mathbb {D} _{12}=\mathbb {Z} _{6}\rtimes \mathbb {Z} _{2}}$
dihexagonal-pyramidal C6v 6mm *66 [6] polar 12 dihedral ${\displaystyle \mathbb {D} _{12}=\mathbb {Z} _{6}\rtimes \mathbb {Z} _{2}}$
ditrigonal-dipyramidal D3h 6m2 or 62m *322 [2,3] non-centrosymmetric 12 dihedral ${\displaystyle \mathbb {D} _{12}=\mathbb {Z} _{6}\rtimes \mathbb {Z} _{2}}$
dihexagonal-dipyramidal D6h 6/mmm *622 [2,6] centrosymmetric 24 ${\displaystyle \mathbb {D} _{12}\times \mathbb {Z} _{2}}$
cubic tetartoidal T 23 332 [3,3]+ enantiomorphic 12 alternating ${\displaystyle \mathbb {A} _{4}}$
diploidal Th m3 3*2 [3+,4] centrosymmetric 24 ${\displaystyle \mathbb {A} _{4}\times \mathbb {Z} _{2}}$
gyroidal O 432 432 [4,3]+ enantiomorphic 24 symmetric ${\displaystyle \mathbb {S} _{4}}$
hextetrahedral Td 43m *332 [3,3] non-centrosymmetric 24 symmetric ${\displaystyle \mathbb {S} _{4}}$
hexoctahedral Oh m3m *432 [4,3] centrosymmetric 48 ${\displaystyle \mathbb {S} _{4}\times \mathbb {Z} _{2}}$
The point symmetry of a structure can be further described as follows. Consider the points that make up the structure, and reflect them all through a single point, so that (x,y,z) becomes (−x,−y,−z). This is the 'inverted structure'. If the original structure and inverted structure are identical, then the structure is centrosymmetric. Otherwise it is non-centrosymmetric. Still, even in the non-centrosymmetric case, the inverted structure can in some cases be rotated to align with the original structure. This is a non-centrosymmetric achiral structure. If the inverted structure cannot be rotated to align with the original structure, then the structure is chiral or enantiomorphic and its symmetry group is enantiomorphic.[1]
A direction (meaning a line without an arrow) is called polar if its two directional senses are geometrically or physically different. A symmetry direction of a crystal that is polar is called a polar axis.[2] Groups containing a polar axis are called polar. A polar crystal possesses a unique polar axis (more precisely, all polar axes are parallel). Some geometrical or physical property is different at the two ends of this axis: for example, there might develop a dielectric polarization as in pyroelectric crystals. A polar axis can occur only in non-centrosymmetric structures. There cannot be a mirror plane or twofold axis perpendicular to the polar axis, because they would make the two directions of the axis equivalent.
The crystal structures of chiral biological molecules (such as protein structures) can only occur in the 65 enantiomorphic space groups (biological molecules are usually chiral).
## Bravais lattices
There are 7 different kinds of crystal systems, and each kind of crystal system has 4 different kinds of centerings (Primitive, Base-centered, Body-centered, Face-centered). However, not all of the combinations are unique; some of the combinations are equivalent while other combinations are not possible due to symmetry reasons. This reduces the number of unique lattices to the 14 Bravais lattices.
The distribution of the 14 Bravais lattices into lattice systems and crystal families is given in the following table.
Crystal family Lattice system Schönflies 14 Bravais Lattices
Primitive Base-centered Body-centered Face-centered
triclinic Ci
monoclinic C2h
orthorhombic D2h
tetragonal D4h
hexagonal rhombohedral D3d
hexagonal D6h
cubic Oh
In geometry and crystallography, a Bravais lattice is a category of translative symmetry groups (also known as lattices) in three directions.
Such symmetry groups consist of translations by vectors of the form
R = n1a1 + n2a2 + n3a3,
where n1, n2, and n3 are integers and a1, a2, and a3 are three non-coplanar vectors, called primitive vectors.
These lattices are classified by the space group of the lattice itself, viewed as a collection of points; there are 14 Bravais lattices in three dimensions; each belongs to one lattice system only. They[clarification needed] represent the maximum symmetry a structure with the given translational symmetry can have.
All crystalline materials (not including quasicrystals) must, by definition, fit into one of these arrangements.
For convenience a Bravais lattice is depicted by a unit cell which is a factor 1, 2, 3 or 4 larger than the primitive cell. Depending on the symmetry of a crystal or other pattern, the fundamental domain is again smaller, up to a factor 48.
The Bravais lattices were studied by Moritz Ludwig Frankenheim in 1842, who found that there were 15 Bravais lattices. This was corrected to 14 by A. Bravais in 1848.
## In four-dimensional space
The four-dimensional unit cell is defined by four edge lengths (a, b, c, d) and six interaxial angles (α, β, γ, δ, ε, ζ). The following conditions for the lattice parameters define 23 crystal families
Crystal families in 4D space
No. Family Edge lengths Interaxial angles
1 Hexaclinic abcd αβγδεζ ≠ 90°
2 Triclinic abcd αβγ ≠ 90°
δ = ε = ζ = 90°
3 Diclinic abcd α ≠ 90°
β = γ = δ = ε = 90°
ζ ≠ 90°
4 Monoclinic abcd α ≠ 90°
β = γ = δ = ε = ζ = 90°
5 Orthogonal abcd α = β = γ = δ = ε = ζ = 90°
6 Tetragonal monoclinic ab = cd α ≠ 90°
β = γ = δ = ε = ζ = 90°
7 Hexagonal monoclinic ab = cd α ≠ 90°
β = γ = δ = ε = 90°
ζ = 120°
8 Ditetragonal diclinic a = db = c α = ζ = 90°
β = ε ≠ 90°
γ ≠ 90°
δ = 180° − γ
9 Ditrigonal (dihexagonal) diclinic a = db = c α = ζ = 120°
β = ε ≠ 90°
γδ ≠ 90°
cos δ = cos β − cos γ
10 Tetragonal orthogonal ab = cd α = β = γ = δ = ε = ζ = 90°
11 Hexagonal orthogonal ab = cd α = β = γ = δ = ε = 90°, ζ = 120°
12 Ditetragonal monoclinic a = db = c α = γ = δ = ζ = 90°
β = ε ≠ 90°
13 Ditrigonal (dihexagonal) monoclinic a = db = c α = ζ = 120°
β = ε ≠ 90°
γ = δ ≠ 90°
cos γ = −1/2cos β
14 Ditetragonal orthogonal a = db = c α = β = γ = δ = ε = ζ = 90°
15 Hexagonal tetragonal a = db = c α = β = γ = δ = ε = 90°
ζ = 120°
16 Dihexagonal orthogonal a = db = c α = ζ = 120°
β = γ = δ = ε = 90°
17 Cubic orthogonal a = b = cd α = β = γ = δ = ε = ζ = 90°
18 Octagonal a = b = c = d α = γ = ζ ≠ 90°
β = ε = 90°
δ = 180° − α
19 Decagonal a = b = c = d α = γ = ζβ = δ = ε
cos β = −1/2 − cos α
20 Dodecagonal a = b = c = d α = ζ = 90°
β = ε = 120°
γ = δ ≠ 90°
21 Diisohexagonal orthogonal a = b = c = d α = ζ = 120°
β = γ = δ = ε = 90°
22 Icosagonal (icosahedral) a = b = c = d α = β = γ = δ = ε = ζ
cos α = −1/4
23 Hypercubic a = b = c = d α = β = γ = δ = ε = ζ = 90°
The names here are given according to Whittaker.[3] They are almost the same as in Brown et al,[4] with exception for names of the crystal families 9, 13, and 22. The names for these three families according to Brown et al are given in parenthesis.
The relation between four-dimensional crystal families, crystal systems, and lattice systems is shown in the following table.[3][4] Enantiomorphic systems are marked with an asterisk. The number of enantiomorphic pairs are given in parentheses. Here the term "enantiomorphic" has a different meaning than in the table for three-dimensional crystal classes. The latter means, that enantiomorphic point groups describe chiral (enantiomorphic) structures. In the current table, "enantiomorphic" means that a group itself (considered as a geometric object) is enantiomorphic, like enantiomorphic pairs of three-dimensional space groups P31 and P32, P4122 and P4322. Starting from four-dimensional space, point groups also can be enantiomorphic in this sense.
Crystal systems in 4D space
No. of
crystal family
Crystal family Crystal system No. of
crystal system
Point groups Space groups Bravais lattices Lattice system
I Hexaclinic 1 2 2 1 Hexaclinic P
II Triclinic 2 3 13 2 Triclinic P, S
III Diclinic 3 2 12 3 Diclinic P, S, D
IV Monoclinic 4 4 207 6 Monoclinic P, S, S, I, D, F
V Orthogonal Non-axial orthogonal 5 2 2 1 Orthogonal KU
112 8 Orthogonal P, S, I, Z, D, F, G, U
Axial orthogonal 6 3 887
VI Tetragonal monoclinic 7 7 88 2 Tetragonal monoclinic P, I
VII Hexagonal monoclinic Trigonal monoclinic 8 5 9 1 Hexagonal monoclinic R
15 1 Hexagonal monoclinic P
Hexagonal monoclinic 9 7 25
VIII Ditetragonal diclinic* 10 1 (+1) 1 (+1) 1 (+1) Ditetragonal diclinic P*
IX Ditrigonal diclinic* 11 2 (+2) 2 (+2) 1 (+1) Ditrigonal diclinic P*
X Tetragonal orthogonal Inverse tetragonal orthogonal 12 5 7 1 Tetragonal orthogonal KG
351 5 Tetragonal orthogonal P, S, I, Z, G
Proper tetragonal orthogonal 13 10 1312
XI Hexagonal orthogonal Trigonal orthogonal 14 10 81 2 Hexagonal orthogonal R, RS
150 2 Hexagonal orthogonal P, S
Hexagonal orthogonal 15 12 240
XII Ditetragonal monoclinic* 16 1 (+1) 6 (+6) 3 (+3) Ditetragonal monoclinic P*, S*, D*
XIII Ditrigonal monoclinic* 17 2 (+2) 5 (+5) 2 (+2) Ditrigonal monoclinic P*, RR*
XIV Ditetragonal orthogonal Crypto-ditetragonal orthogonal 18 5 10 1 Ditetragonal orthogonal D
165 (+2) 2 Ditetragonal orthogonal P, Z
Ditetragonal orthogonal 19 6 127
XV Hexagonal tetragonal 20 22 108 1 Hexagonal tetragonal P
XVI Dihexagonal orthogonal Crypto-ditrigonal orthogonal* 21 4 (+4) 5 (+5) 1 (+1) Dihexagonal orthogonal G*
5 (+5) 1 Dihexagonal orthogonal P
Dihexagonal orthogonal 23 11 20
Ditrigonal orthogonal 22 11 41
16 1 Dihexagonal orthogonal RR
XVII Cubic orthogonal Simple cubic orthogonal 24 5 9 1 Cubic orthogonal KU
96 5 Cubic orthogonal P, I, Z, F, U
Complex cubic orthogonal 25 11 366
XVIII Octagonal* 26 2 (+2) 3 (+3) 1 (+1) Octagonal P*
XIX Decagonal 27 4 5 1 Decagonal P
XX Dodecagonal* 28 2 (+2) 2 (+2) 1 (+1) Dodecagonal P*
XXI Diisohexagonal orthogonal Simple diisohexagonal orthogonal 29 9 (+2) 19 (+5) 1 Diisohexagonal orthogonal RR
19 (+3) 1 Diisohexagonal orthogonal P
Complex diisohexagonal orthogonal 30 13 (+8) 15 (+9)
XXII Icosagonal 31 7 20 2 Icosagonal P, SN
XXIII Hypercubic Octagonal hypercubic 32 21 (+8) 73 (+15) 1 Hypercubic P
107 (+28) 1 Hypercubic Z
Dodecagonal hypercubic 33 16 (+12) 25 (+20)
Total 23 (+6) 33 (+7) 227 (+44) 4783 (+111) 64 (+10) 33 (+7) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 32, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6657027006149292, "perplexity": 6425.8480939815545}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-26/segments/1560627999482.38/warc/CC-MAIN-20190624104413-20190624130413-00306.warc.gz"} |
https://proofwiki.org/wiki/Definition:Greatest_Lower_Bound | Definition:Infimum of Set/Real Numbers
Definition
Let $T \subseteq \R$.
A real number $c \in \R$ is the infimum of $T$ in $\R$ if and only if:
$(1): \quad c$ is a lower bound of $T$ in $\R$
$(2): \quad d \le c$ for all lower bounds $d$ of $T$ in $\R$.
If there exists an infimum of $T$ (in $\R$), we say that $T$ admits an infimum (in $\R$).
The infimum of $T$ is denoted $\inf T$ or $\map \inf T$.
Also known as
Particularly in the field of analysis, the infimum of a set $T$ is often referred to as the greatest lower bound of $T$ and denoted $\map {\mathrm {glb} } T$ or $\map {\mathrm {g.l.b.} } T$.
Some sources refer to the infimum of a set as the infimum on a set.
Some sources introduce the notation $\displaystyle \inf_{y \mathop \in S} y$, which may improve clarity in some circumstances.
Some older sources, applying the concept to a (strictly) decreasing real sequence, refer to a infimum as a lower limit.
Also defined as
Some sources refer to the infimum as being the lower bound.
Using this convention, any element less than this is not considered to be a lower bound.
Examples
Example 1
The subset $S$ of the real numbers $\R$ defined as:
$S = \set {1, 2, 3}$
$\inf S = 1$
Example 2
The subset $T$ of the real numbers $\R$ defined as:
$T = \set {x \in \R: 1 \le x \le 2}$
$\inf T = 1$
Example 3
The subset $V$ of the real numbers $\R$ defined as:
$V := \set {x \in \R: x > 0}$
$\inf V = 0$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9941575527191162, "perplexity": 196.90900974757932}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178363782.40/warc/CC-MAIN-20210302065019-20210302095019-00599.warc.gz"} |
https://astarmathsandphysics.com/university-maths-notes/topology/2233-proof-that-a-sequentially-compact-subset-of-a-metric-space-is-compact.html | ## Proof That a Sequentially Compact Subset of a Metric Space is Compact
Theorem
A sequentially compact subsetof a metric spaceis compact.
Proof
Letbe a sequentially compact subset of a metric spaceand letbe an open cover ofThe sethas a Lebesgue numbersince every open cover of a sequentially compact subset of a metric space has a Lebesgue number. Sinceis totally bounded, there is a decomposition ofinto a finite number of subsetswith whereis the diameter of the subset
is a Lebesgue number ofso there are open setssuch that
Henceandis a finite subcover. Henceis compact. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9874634146690369, "perplexity": 1102.6685379836156}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-05/segments/1516084886416.17/warc/CC-MAIN-20180116105522-20180116125522-00038.warc.gz"} |
http://mathhelpforum.com/algebra/155441-matrix-multiplication.html | # Math Help - matrix multiplication,
1. ## matrix multiplication,
Hi,
I have a matrix that looks like the following.
$
A = \left[\begin{matrix} 3 & 9 \\ 5 & 2 \\ 1 & 4 \end{matrix}\right]
$
by doing the following, I can add the two columns.
$
\left[\begin{matrix} 3 & 9 \\ 5 & 2 \\ 1 & 4 \end{matrix}\right] * \left[\begin{matrix} 1 \\ 1 \end{matrix}\right] = \left[\begin{matrix} 12 \\ 7 \\ 5 \end{matrix}\right]
$
My question is:
Is there any clever way to multiply columns in the matrix.
$
\left[\begin{matrix} 3 & 9 \\ 5 & 2 \\ 1 & 4 \end{matrix}\right] * X = \left[\begin{matrix} 18 \\ 10 \\ 4 \end{matrix}\right]
$
Can X be a matrix of any kind?
Regards
Craig.
2. X must be a 2 x 1 matrix. You could let it have elements a and b, and try solving simultaneously.
3. You need to take into account the dimensions of the matrix.
You know that for matrices $A$ and $B$, the number of columns in $A$ has to equal the number of rows in $B$ to be able to multiply them. And if $A$ has dimensions $m \times n$ and $B$ has dimensions $n \times p$, then $AB$ has dimensions $m \times p$.
So you have a $3 \times 2$ multiplied by $X$ to give $3 \times 1$.
That means $X$ has dimensions $2 \times 1$.
There are two ways to solve this.
The first is to write $X$ as $\left[\begin{matrix}x\\y\end{matrix}\right]$ so that your equation is
$\left[\begin{matrix}3 & 9\\ 5 & 1\\ 1 & 4\end{matrix}\right] \left[\begin{matrix}x\\y\end{matrix}\right] = \left[\begin{matrix}18\\10\\4\end{matrix}\right]$.
Perform the multiplication on the LHS to get
$3x + 9y = 18$
$5x + y = 10$
$x + 4y = 4$.
Solve for $x$ and $y$.
The other way is to create a "pseudo-inverse" matrix.
If you have an equation
$A\mathbf{x} = B$
only square matrices have inverses, so to create a square matrix on the LHS, premultiply both sides by $A^T$.
$A^TA\mathbf{x} = A^TB$.
Since $A^TA$ is square, you can multiply both sides by its inverse (as long as it's invertible).
$A^TA\mathbf{x} = A^TB$
$(A^TA)^{-1}A^TA\mathbf{x} = (A^TA)^{-1}A^TAB$
$I\mathbf{x} = (A^TA)^{-1}A^TB$
$\mathbf{x} = (A^TA)^{-1}A^TB$.
4. Originally Posted by craigmain
Hi,
I have a matrix that looks like the following.
$
A = \left[\begin{matrix} 3 & 9 \\ 5 & 1 \\ 1 & 4 \end{matrix}\right]
$
by doing the following, I can add the two columns.
$
\left[\begin{matrix} 3 & 9 \\ 5 & 1 \\ 1 & 4 \end{matrix}\right] * \left[\begin{matrix} 1 \\ 1 \end{matrix}\right] = \left[\begin{matrix} 12 \\ 7 \\ 5 \end{matrix}\right]
$
My question is:
Is there any clever way to multiply columns in the matrix.
$
\left[\begin{matrix} 3 & 9 \\ 5 & 1 \\ 1 & 4 \end{matrix}\right] * X = \left[\begin{matrix} 18 \\ 10 \\ 4 \end{matrix}\right]
$
Can X be a matrix of any kind?
Regards
Craig.
this can be done
$\displaystyle \begin{bmatrix}
a_{11} & a_{12}\\
a_{21} & a_{22} \\
a_{31} & a_{32}
\end{bmatrix} \cdot \begin{bmatrix}
b_{11} \\
b_{12}
\end{bmatrix}$
meaning that matrix A(m x n) can be multiplied with another matrix B (n x m) only if matrix B have same number of the columns as the matrix A have rows
important is that (mostly)
$A\cdot B \ne B\cdot A$
only in some cases can be $AB = BA$
as for the your problem there
$\displaystyle \left[\begin{matrix} 3 & 9 \\ 5 & 1 \\ 1 & 4 \end{matrix}\right] * X = \left[\begin{matrix} 18 \\ 10 \\ 4 \end{matrix}\right]$
your X can be $X= \begin{bmatrix}
x_1 \\
x_2
\end{bmatrix}$
so when multiplied you get system of equations like :
$3x_1+9x_2=18$
$5x_1+x_2=10$
$x_1+4x_2=4$
Edit : sorry Prove It I have no idea why i didn't see your post .... early hm... very very sorry (P.S. when i refreshed this thread it wasn't there, and i waited to my post be posted at least 5 min. don't know what just happen .... ) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 45, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8726719617843628, "perplexity": 356.0766630127307}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-35/segments/1440645257890.57/warc/CC-MAIN-20150827031417-00232-ip-10-171-96-226.ec2.internal.warc.gz"} |
https://gauravtiwari.org/math/recreations/?amp=1 | # Recreations
## Abel Prize Laureates
Abel prize is one of the most prestigious awards given for outstanding contribution in mathematics, often considered as the Nobel Prize of Mathematics. Niels Henrik Abel Memorial fund, established on 1 January 2002, awards the Abel Prize for outstanding scientific work in the field of mathematics. The prize amount is 6 million NOK (about 1010000 USD) and
## This Prime Generating Product generates successive prime factors
Any integer greater than 1 is called a prime number if and only if its positive factors are 1 and the number p itself. The basic ideology involved in this post is flawed and the post has now been moved to Archives. – The Editor Prime Generating Formulas We all know how hard it is to predict a formula
## 11-12-13 – Last such sequence of the century
11th December 2013 (or in short 11-12-13) is just a few hours away here. It’s the last date of the 21st century with such an extraordinary pattern of numbers. In any calendar of the world, such date will be seen in 22nd century after 87 years and 54 days from today — on February 3, 2101,
## Examination Strategies : Tactics & Tips
Every student or graduate knows how hard the first experience of passing exams is. Preliminary preparation starves the nervous system and the physical condition of the human body, however, the exam itself is always a stressful situation, which requires a candidate a great manifestation of mental and physical abilities. Therefore, just the knowledge of a
## Some good, OK, and useless revision techniques
Exams have been haunting students forever, and although you’re willing to do whatever you can to retain essential information, sometimes you end up spending weeks studying with useless revision techniques. We’re accustomed to employing our own techniques when it comes to studying such as making sticky notes, highlighting, or drawing charts. However, recent studies conducted
## Hopalong Orbits Visualizer: Stunning WebGL Experiment
Just discovered Barry Martin’s Hopalong Orbits Visualizer — an excellent abstract visualization, which is rendered in 3D using Hopalong Attractor algorithm, WebGL and Mrdoob’s three.js project. Hop to the source website using your desktop browser (with WebGl and Javascript support) and enjoy the magic. PS: Hopalong Attractor Algorithm Hopalong Attractor predicts the locus of points
## Smart Fallacies: i=1, 1= 2 and 1= 3
This mathematical fallacy is due to a simple assumption, that $-1=\dfrac{-1}{1}=\dfrac{1}{-1}$ . Proceeding with $\dfrac{-1}{1}=\dfrac{1}{-1}$ and taking square-roots of both sides, we get: $\dfrac{\sqrt{-1}}{\sqrt{1}}=\dfrac{\sqrt{1}}{\sqrt{-1}}$ Now, as the Euler’s constant $i= \sqrt{-1}$ and $\sqrt{1}=1$ , we can have $\dfrac{i}{1}=\dfrac{1}{i} \ldots \{1 \}$ $\Rightarrow i^2=1 \ldots \{2 \}$ . This
## Interesting Egyptian Fraction Problem
Here is an interesting mathematical puzzle alike problem involving the use of Egyptian fractions, whose solution sufficiently uses the basic algebra. Problem Let a, b, c, d and e be five non-zero complex numbers, and; $a + b + c + d + e = -1$ … (i) $a^2+b^2+c^2+d^2+e^2=15$ …(ii) \$ \dfrac{1}{a} +
We are now on Telegram! | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6690327525138855, "perplexity": 2371.34522124831}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-40/segments/1600400232211.54/warc/CC-MAIN-20200926004805-20200926034805-00583.warc.gz"} |
http://mathhelpforum.com/pre-calculus/37195-urgent-very-easy-vector-exercise-print.html | # URGENT! Very easy Vector exercise!
• May 5th 2008, 12:51 AM
Akuma666
URGENT! Very easy Vector exercise!
It's supposed to be a parallelogram.
O (0;0)
P (6;8)
Q (9;14)
Vector OP and OQ are parallelogram sides.
I need this parallelogram diagonals and their edge-top coordinates.
And if possible, then drawing too!
It's very easy, all you need is one edge-top to find!
First diag : OP + OQ =
Sec. diag : OP - OQ =
Thanks!!
• May 5th 2008, 02:32 AM
topsquark
Quote:
Originally Posted by Akuma666
It's supposed to be a parallelogram.
O (0;0)
P (6;8)
Q (9;14)
Vector OP and OQ are parallelogram sides.
I need this parallelogram diagonals and their edge-top coordinates.
And if possible, then drawing too!
It's very easy, all you need is one edge-top to find!
First diag : OP + OQ =
Sec. diag : OP - OQ =
Thanks!!
Try looking at it this way. The opposite sides in a parallelogram are equal and parallel. So if the last point in your parallelogram is R then we know that vector OP and vector QR are equal. Similarly vectors OQ and PR are equal.
-Dan
• May 5th 2008, 03:39 AM
Akuma666
I have this drawing in my notebook right now and well it looks SO weird, i'd really feel more comfortable if I'd knew it is correct one, this simple exercise is actually very important.
Could you please or anyone else make the drawing and give me the vector numbers? (Thinking)
Thanks.
• May 5th 2008, 03:45 AM
topsquark
Quote:
Originally Posted by Akuma666
I have this drawing in my notebook right now and well it looks SO weird, i'd really feel more comfortable if I'd knew it is correct one, this simple exercise is actually very important.
Could you please or anyone else make the drawing and give me the vector numbers? (Thinking)
Thanks.
Quote:
Originally Posted by Akuma666
O (0;0)
P (6;8)
Q (9;14)
Well the vector OP is the directed line segment from (0, 0) to (6, 8), so it has the vector coordinates <6, 8>.
Since OP = QR, we can base the vector <6, 8> at point Q and travel 6 units to the right and 8 units up to get point R.
-Dan
• May 5th 2008, 03:47 AM
james_bond
1 Attachment(s)
$\vec{OA}=\vec{OP}+\vec{OQ}=(15,22)\qquad \vec{QP}=\vec{OP}-\vec{OQ}=(-3,-6)$
• May 5th 2008, 03:48 AM
Akuma666
Thank you both very much! I'm very glad someone helped me with this. ^_^
• May 5th 2008, 03:49 AM
topsquark
Quote:
Originally Posted by james_bond
$\vec{OP}+\vec{OQ}=(15,22)\qquad \vec{OP}-\vec{OQ}=(-3,-6)$
(Chuckles)
That diagram is not only very large, but the parallelogram is so squished that it is almost impossible to make out any details! Try reducing the size and changing the scale of the x and y axis a bit.
-Dan | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 2, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7169749736785889, "perplexity": 2672.700218490165}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1405997895170.20/warc/CC-MAIN-20140722025815-00117-ip-10-33-131-23.ec2.internal.warc.gz"} |
http://nrich.maths.org/10142/index?nomenu=1 | Which of the following has the greatest value?
(a) $\left(\frac{11}{7}\right)^3$
(b) $\left(\frac{5}{3}\right)^3$
(c) $\left(\frac{7}{4}\right)^3$
(d) $\left(\frac{9}{5}\right)^3$
(e) $\left(\frac{3}{2}\right)^3$
If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.
This problem is taken from the UKMT Mathematical Challenges.
View the archive of all weekly problems grouped by curriculum topic
View the previous week's solution
View the current weekly problem | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3167073428630829, "perplexity": 3044.931000641273}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-18/segments/1461860121423.81/warc/CC-MAIN-20160428161521-00213-ip-10-239-7-51.ec2.internal.warc.gz"} |
https://www.realnfo.com/toc/Basic_Electrical_Engineering/Electricity_and_Magnetism/Magnetism/Magnetic_Flux | Magnetic Flux
Show Profile
Wilhelm Eduard Weber
Wilhelm Eduard Weber
Physicist
October 24, 1804 - June 23, 1891
An important contributor to the establishment of a system of absolute units for the electrical sciences, which was beginning to become a very active area of research and development. Established a definition of electric current in an electromagnetic system based on the magnetic field produced by the current. He was politically active and, in fact, was dismissed from the faculty of the University of Gottingen for protesting the suppression of the constitution by the King of Hanover in 1837. However, he found other faculty positions and eventually returned to Gottingen as director of the astronomical observatory. Received honors from England, France, and Germany, including the Copley Medal of the Royal Society.
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What is Magnetic Flux?
Magnetic flux is a measure of the amount of magnetic field passing through a given surface (such as a conducting coil).
It gives the measurement of the total magnetic field that passes through a given surface area. Here, the area under consideration can be of any size and under any orientation with respect to the direction of the magnetic field.
Fig.no.1: Magnetic flux
Magnetic Flux Symbol
Magnetic flux is commonly denoted using greek letter Phi ($\Phi _B$).
Magnetic Flux Formula
Magnetic flux formula is given by: $$\Phi _B = B.A=BA \, cos\theta \, \text{(weber)}$$ Where,
$\Phi _B$ is the magnetic flux.
B is the magnetic field.
A is the area
$\theta$, the angle at which the field lines pass through the given surface area.
Magnetic Flux Unit
The unit of the magnetic flux is the tesla meter squared ($T. m^2$, also called the weber - the SI unit of magnetic flux and symbolized Wb). The older units for the magnetic flux, the Maxwell (equivalent to $10^{-8}$ Wb). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9566013813018799, "perplexity": 960.3579504652049}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764500384.17/warc/CC-MAIN-20230207035749-20230207065749-00145.warc.gz"} |
http://www.talkstats.com/tags/ljung-box-q/ | # ljung-box q
1. ### Timeseries: sig. Ljung-box Q, but residuals normally distributed
Hi all, Hope someone can help me with the following problem/question I encounter. I'm working with a monthly time-serie consisting of 36 data points (i know 50 is the rule of thumb). Spss expert modeler chose Winter's multiplicative model, which is fine with me because I know how such a... | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9420735836029053, "perplexity": 4406.786540186648}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030335054.79/warc/CC-MAIN-20220927162620-20220927192620-00450.warc.gz"} |
http://docmadhattan.fieldofscience.com/2014/07/fifty-years-of-cp-violation.html | Fifty years of CP violation
via @CERN http://t.co/9Rac42mBVh #CPviolation #CPsymmetry #matter #antimatter
The CP violation is a violation of the CP-symmetry, a combination between the charge conjugation symmetry (C) and the parity symmetry (P).
CP-symmetry states that the laws of physics should be the same if a particle is interchanged with its antiparticle, and then its spatial coordinates are inverted.
The CP violation is discovered in 1964 by Christenson, Cronin, Fitch, and Turlay (Cronin and Fitch awarded the Nobel Prize in 1980) studying the kaons' decays and it could have a key-role in the matter-antimatter imbalance. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.903747022151947, "perplexity": 1979.5955025946205}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886133449.19/warc/CC-MAIN-20170824101532-20170824121532-00590.warc.gz"} |
http://mymathforum.com/complex-analysis/336286-graphing-set.html | My Math Forum graphing set
User Name Remember Me? Password
Complex Analysis Complex Analysis Math Forum
October 1st, 2016, 08:57 AM #1 Newbie Joined: Oct 2016 From: Lawrence, Kansas Posts: 2 Thanks: 0 graphing set How do I graph a set that is defined as z given that |z -[complex number]| <= 1 (apologies: I am approaching an online class with an undeniably weak background, but with determination....). Last edited by skipjack; October 22nd, 2016 at 11:31 AM.
October 1st, 2016, 09:06 AM #2 Senior Member Joined: Sep 2015 From: USA Posts: 1,653 Thanks: 840 You'll see the expression $|z - z_0|$ a lot. The region $|z-z_0| \leq \rho$ is a disk on the complex plane of radius $\rho$, centered at the point $z_0$. Thanks from Dan dimmitt Last edited by skipjack; October 22nd, 2016 at 11:32 AM.
October 1st, 2016, 09:27 AM #3 Newbie Joined: Oct 2016 From: Lawrence, Kansas Posts: 2 Thanks: 0 Thanks! Last edited by skipjack; October 22nd, 2016 at 11:31 AM.
October 22nd, 2016, 10:38 AM #4 Math Team Joined: Jan 2015 From: Alabama Posts: 2,875 Thanks: 766 Specifically, in the "complex" plane z= x+ iy. Writing point $\displaystyle z_0$ as a+ iy, then $\displaystyle |z- z_0|= |x+ iy- (a+ ib)|= |(x- a)+ i(y- b)|= \sqrt{(x-a)^2+ (y- b)^2}$ so that $\displaystyle |z- z_0|\le \rho$ is $\displaystyle \sqrt{(x- a)^2+ (y- b)^2}\le \rho$ and squaring both sides, $\displaystyle (x- a)^2+ (y- b)^2\le \rho^2$. $\displaystyle (x- a)^2+ (y- b)^2= \rho^2$ is the circle, in the complex plane with center $\displaystyle z_0= a+ ib$ and radius $\displaystyle \rho$.
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http://www.newton.ac.uk/seminar/20180403110012002 | # Inference for the mode of a log-concave density: a likelihood ratio test and confidence intervals
Presented by:
Jon August Wellner University of Washington
Date:
Tuesday 3rd April 2018 - 11:00 to 12:00
Venue:
INI Seminar Room 2
Abstract:
I will discuss a likelihood ratio test for the mode of a log-concave density. The new test is based on comparison of the log-likelihoods corresponding to the unconstrained maximum likelihood estimator of a log-concave density and the constrained maximum likelihood estimator, where the constraint is that the mode of the density is fixed, say at m. The constrained estimators have many properties in common with the unconstrained estimators discussed by Walther (2001), Pal, Woodroofe, and Meyer (2007), Dümbgen and Rufibach (2009), and Balabdaoui, Rufibach and Wellner (2010), but they differ from the unconstrained estimator under the null hypothesis on n^{−1/5} neighborhoods of the mode m. Using joint limiting properties of the unconstrained and constrained estimators we show that under the null hypothesis (and strict curvature of - log f at the mode), the likelihood ratio statistic is asymptotically pivotal: that is, it converges in distribution to a limiting distribution which is free of nuisance parameters, thus playing the role of the chi-squared distribution in classical parametric statistical problems. By inverting this family of tests, we obtain new (likelihood ratio based) confidence intervals for the mode of a log-concave density f. These new intervals do not depend on any smoothing parameters. We study the new confidence intervals via Monte Carlo studies and illustrate them with several real data sets. The new confidence intervals seem to have several advantages over existing procedures. This talk is based on joint work with Charles Doss. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9672989249229431, "perplexity": 557.2583547117882}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-13/segments/1552912203755.18/warc/CC-MAIN-20190325051359-20190325073359-00055.warc.gz"} |
http://www.bankersguruadda.com/2016/10/quantitative-aptitude-quiz-104-for-ibps.html | ## Quantitative Aptitude Quiz 104 for IBPS PO
Directions (Q. 1-5): Study the graph carefully to answer the questions that follow : The graph represents the total productions (in tons) and total sales (in tons) of company A and B o f six years
The below table represents the ratio of the production (in tons) of company A and B, and the ratio o f the sales of company A in (in tons) to the sales of company B (in tons) :
1. What is the ratio of the production of company B (in tons) in the year 2010 to sales of company A in 2008 ?
1) 16 : 164 2) 64 : 165 3) 33 : 32 4) 644 : 165 5) None of these
2. What is the ratio of total production of company B in the year 2008 and 2010 to the sales of company B in the same years?
1) 44 : 81 2) 81 : 44 3) 95 : 81 4) 59 : 81 5) None of these
3. What is the average sales (in tons) of company B in all over the years ?
1) 149.67 tons 2) 148.33 tons 3) 147.67 tons 4) 150.67 tons 5) None of these
4. What is the average production of company B in years – 2008, 2009, 2010 ?
1) 345.33 tons 2) 343.33 tons 3) 353.33 tons 4) 348.33 tons 5) None of these
5. The sales of company B in the year 2008 is what % of production of company B in the same year ?
1) 36.5 % 2) 37.5 % 3) 38.5 % 4) 39.5 % 5) None of these
Direction (Q. 6-10): Read the graph carefully to answer the questions that follows :
Percentage profit earned by two companies by selling mobiles phones over the year :
6. If the profit earned by company B in 2008 was 812500. What was the total income of the company in that year ?
1) 3437500 2) 2437500 3) 2462500 4) 3637500 5) None of these
7. If the amount invested by both companies A and B in year 2010 was equal what was the ratio of the in come of the company B to A in same year ?
1) 16 : 13 2) 13 : 16 3) 15 : 14 4) 14 : 15 5) None of these
8. If the income of both companies A and B was equal in the year 2008, what was the ratio of the expenditure of company A to B in the same year ?
1) 5 : 2 2) 5 : 4 3) 6 : 2 4) 2 : 6 5) None of these
9. If the income of company A in 2007 and that in 2009 was equal and the amount invested in 2007 by company A is 40 lakh, what was the amount invested in 2009 ?
1) 44.44 lakh 2) 54.44 lakh 3) 64.44 lakh 4) 34.44 lakh 5) None of these
10. If the expenditure of company B in 2009 is 60 lakh. Find the income of same company in same year ?
1) 86 lakh 2) 76 lakh 3) 96 lakh 4) `85 lakh 5) None of these
For More Materials
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http://mathhelpforum.com/discrete-math/215278-sum-series-print.html | # Sum of the series
• March 22nd 2013, 07:58 AM
Shakarri
Sum of the series
I am struggling to see a way of finding the infinite sum of the series
$2sin(\frac{1}{k}-\frac{1}{k+1})cos(\frac{1}{k}+\frac{1}{k+1})$
$sin(\frac{1}{k}-\frac{1}{k+1})$ converges to 0 and $cos(\frac{1}{k}+\frac{1}{k+1})$ converges to 1.
Expanding and simplifying the trig functions just yields
$2(sin(\frac{1}{k})cos(\frac{1}{k})cos(\frac{2}{k+1 })-sin(\frac{1}{k+1})cos(\frac{1}{k+1})cos(\frac{2}{k }))$
Which is not of any use
We didn't cover many methods for finding the sum of series in class, just ways of showing that a series converges :(
Could someone point me in the right direction?
• March 22nd 2013, 05:25 PM
Nehushtan
Re: Sum of the series
$2\sin\left(\frac1k - \frac1{k+1}\right)\cos\left(\frac1k + \frac1{k+1}\right)\,=\,\sin\frac2k-\sin\frac2{k+1}$
$\sum_{k=1}^n\left[\sin\frac2k-\sin\frac2{k+1}\right]\,=\,\sin2-\sin\frac2{n+1}\to\sin2\ \mbox{as}\ n\to\infty$
• March 23rd 2013, 09:07 AM
Shakarri
Re: Sum of the series
At first I didnt see what you did but now I see its a telescoping series! thank you | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 6, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9747049808502197, "perplexity": 881.8007896470252}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-30/segments/1469257826916.34/warc/CC-MAIN-20160723071026-00227-ip-10-185-27-174.ec2.internal.warc.gz"} |
http://math.stackexchange.com/questions/172012/prove-existence-uniqueness-of-a-certain-operator-on-hilbert-space | # Prove existence/uniqueness of a certain operator on Hilbert Space
Trying to solve this question: Let $\mathcal{H},(\cdot,\cdot)$ be a real Hilbert space, and $\{e_n\}_{n=1}^\infty$ an orthonormal basis on $\mathcal{H}$. Let $F:[0,1]\rightarrow \mathcal{H}$ be continuous. Show that there exists a unique positive self-adjoint operator $T \in B(\mathcal{H})$ such that:
$$(Tx,y) = \int_0^1(F(t),x)(F(t),y)dt \quad \text{ for all } x,y \in \mathcal{H}.$$
Also show that $T$ is compact.
As hint we got that we may use $\lim_{N\rightarrow \infty}\int_0^1\sum_{n=N+1}^\infty|(F(t),e_n)|^2\,dt = 0$.
So far all I've come up with is that $\int_0^1 (F(t),F(t))dt = \lim_{N \rightarrow \infty}\int_0^1\sum_{n=1}^N|(F(t),e_n)|^2dt$ but I have no idea where I'm going with this.
Is there a smarter way to doing this than actually finding an operator which fits all the conditions?
-
Hint (1): Show that $\int_0^1 (F(t),x)(F(t),y)dt$ is a bounded bilinear operator. The rest would follow from Riesz Representation Theorem.
Edit: I add an extra hint.
Hint (2): A bilinear map $\sigma: H\times H\to\mathbb R$ is bounded if there exists $M$ such that $|\sigma(x,y)|\leq M\|x\| \|y\|$. If $\sigma$ is a bounded bilinear map then there exists a bounded operator $u:H\to H$ so that $\sigma(x,y)=\langle u(x), y\rangle$ (here $\langle, \rangle$ denotes the inner product of $H$). Moreover, if $\sigma$ is positive definite then $u$ is positive and self-adjoint. This follows (easily) from the Riesz Representation Theorem you mentioned in the comments.
-
All right, I'll see if I can work this out. – BallzofFury Jul 18 '12 at 12:41
How its stated in my book doesn't seem applicable here to me. For $\mathcal{H}$ a Hilbert space and $f \in B(\mathcal{H},\mathcal{R})$ there exists a unique $y \in \mathcal{H}$ such that $f_y(x) = (x,y)$ for all $x \in \mathcal{H}$. If we do this in each argument, doesn't it just prove it for a single point in each argument, and not for all combinations of $x$ and $y$? – BallzofFury Jul 18 '12 at 13:08
@BallzofFury That's not the version I had in mind. I'll add a further hint. – azarel Jul 18 '12 at 17:45
Right, worked that out. Right now I have everything except for the boundedness of $T$. I tried working it out as $|Tx|^2=\langle Tx,Tx\rangle=\langle TTx,x\rangle \leq |T||Tx||x|$ but I can't get any further. – BallzofFury Jul 18 '12 at 21:26
@BallzofFury To prove that the integral is bounded just apply Caucy-Schwarz inequality and the compactness of $[0,1]$. – azarel Jul 18 '12 at 21:56
For the interested: To prove the existence of such an operator, let $x \in \mathcal{H}$ and define the following function $f_x(y):= \int_0^1 (F(t),x)(F(t),y)\,dt$. We will show that this function is bounded, namely: \begin{align*} |f_x(y)| &= |\int_0^1 (F(t),x)(F(t),y)\,dt| \\ &\leq \int_0^1 |(F(t),x)(F(t),y)|\,dt \\ & = \int_0^1 |(F(t),x)||(F(t),y)|\,dt \\ &\leq |x|\int_0^1 |F(t)|^2\,dt |y| \quad \text{(Cauchy-Schwarz)} \\ &\leq|x| \max_{t \in [0,1]}|F(t)|^2 |y| \end{align*} which gives that $f$ is a bounded operator since $f$ is continuous in the compact interval $[0,1]$, so attains a maximum. Due to the fact that $f$ is bounded, by the Riesz-Fr\'echet representation theorem there exists a unique $z \in \mathcal{H}$ such that $f(x) = (z,y)$. We then define $T$ such that $T(x) = z$. This shows that there exists a unique $T$ such that for all $x,y \in \mathcal{H}$ we have $(Tx,y) = \int_0^1 (F(t),y)(F(t),x)\,dt$.
Now we want to show that $T \in B(\mathcal{H})$, so that it is linear and bounded. For linear, let $x_1,x_2 \in \mathcal{H}$ and $\lambda,\mu \in \mathcal{R}$. Then: \begin{align*} (T(\lambda x_1 + \mu x_2),y) &= \int_0^1 (F(t),\lambda x_1 + \mu x_2)(F(t),y)\,dt \\ &= \int_0^1 (\lambda(F(t),x_1) + \mu(F(t),x_2))(F(t),y)\,dt \\ &= \lambda\int_0^1 (F(t),x_1)(F(t),y)\,dt + \mu\int_0^1 (F(t),x_2)(F(t),y)\,dt \\ &= \lambda(Tx_1,y) + \mu(Tx_2,y) = (\lambda Tx_1,y) + (\mu Tx_2,y) \end{align*} which proves linearity. Now for the boundedness of $T$, take $x \in \mathcal{H}$ then we have by Cauchy-Schwarz that: \begin{align*} |Tx|^2 &= (Tx,Tx) \\ &= \int_0^1 (F(t),x)(F(t),Tx)\,dt \\ &= \int_0^1 (F(t),x)\int_0^1 (F(t),x)(F(t),F(t))\,dt\,dt \\ &= \int_0^1 (F(t),x)^2 |F(t)|^2 \,dt \\ &\leq \left(\int_0^1 |F(t)|^4\,dt\right) |x|^2 \leq \max_{t \in [0,1]}|F(t)|^4 |x|^2 \end{align*} which in turn implies that $|Tx| \leq \max_{t\in[0,1]}|F(t)|^2 |x|$. Therefore $T \in B(\mathcal{H})$.
We will now show that $T$ is a positive operator. Let $x \in \mathcal{H}$, then: \begin{align*} (Tx,x) &= \int_0^1 (F(t),x)(F(t),x)\,dt \\ &= \int_0^1 (F(t),x)^2\,dt \geq 0 \end{align*} since $(F(t),x)^2 \geq 0$ for all $x \in \mathcal{H}$ and all $t \in [0,1]$. For the self-adjoint condition, this is easily seen since we are working on a real Hilbert space. Then: \begin{align*} (Tx,y) &= \int_0^1 (F(t),x)(F(t),y)\,dt \\ &= \int_0^1 (F(t),y)(F(t),x)\,dt \\ &= (Ty,x) = (x,Ty). \end{align*}
As the last required property, we will show that $T$ is a compact operator. Look at the following: \begin{align*} \sum_{n=1}^\infty |Te_n|^2 &= \sum_{n=1}^\infty (Te_n,Te_n) \\ &= \sum_{n=1}^\infty \int_0^1 (F(t),e_n)\int_0^1 (F(t),e_n)(F(t),F(t))\,dt\,dt \\ &= \int_0^1 |F(t)|^2 \sum_{n=1}^\infty (F(t),e_n)(e_n,F(t)) \,dt \\ &= \int_0^1 |F(t)|^2 |F(t)|^2\, dt \quad \text{(by Parseval relation Q3.24)} \\ &\leq \max_{t \in [0,1]}|F(t)|^4 \end{align*} which is bounded by the compactness of $[0,1]$, which means that $T$ is a Hilbert-Schmidt operator and therefore compact.
-
This is just a hint.
If the operator exists, then uniqueness, positivity and self-adjointedness (?) all follow from the formula.
For existence, consider the numbers $\alpha_{n,m} = \int_0^1(F(t),e_n)(F(t),e_m)dt$. Show that $\sum |\alpha_{n,m}|^2 < K$, for some $K$. Then define $T$ so that $\alpha_{n,m} = \langle T e_n, e_m \rangle$. Show $T$ is bounded.
To show compactness, show that $T$ is the norm limit of a sequence of finite rank operators (each of which is compact by finite rank). The norm limit of a sequence of compact operators is compact. The form of $T$ should suggest an obvious finite rank operator.
- | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 1.0000098943710327, "perplexity": 164.0609897588943}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1405997894473.81/warc/CC-MAIN-20140722025814-00118-ip-10-33-131-23.ec2.internal.warc.gz"} |
http://www.ni.com/documentation/en/labview-comms/1.0/mnode-ref/log/ | Version:
Computes the natural logarithm of the input elements.
The natural logarithm of zero is -inf.
## Syntax
c = log(a)
## a
Scalar or array of any dimension of floating point or complex numbers.
## c
Natural logarithm of the elements in a. c returns complex numbers for negative or complex elements in a. c is an array of the same size as a. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4186287224292755, "perplexity": 1251.5277550414874}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-34/segments/1534221218899.88/warc/CC-MAIN-20180821191026-20180821211026-00252.warc.gz"} |
https://www.physicsforums.com/threads/help-calculation-torque-moments.277296/ | # Help calculation torque, moments.
1. Dec 5, 2008
### tweety1234
1. The problem statement, all variables and given/known data
A uniform rod AB of length 4m and mass 2kg is suspended in a horizontal position by two vertical strings attached at points p and Q where AP=1m and AQ=3m. When a particle of mass 3kg is attached at point R of the rod, the rod is on the point of turning about point P. Calculate the distance AR.
3. The attempt at a solution
As the rod is on the point of tilting about P than, Rp =0
I have drawn the diagram and have attached with this post, but i am not sure it is correct, and also I am not quite sure were to put point 'R' on my diagram.
the moments equation that I have come up with is;
taking moments about P
$$2kg + 3kg (xm-3m)=0$$
$$2 \times 9.8 + 3 \times 9.8 (xm-3m) =0$$
$$19.6 + 29.4x-88.2=0$$
$$29.4x-68.2=0$$
$$29.4x=68.2$$
$$x = 2.3$$
I think my moments equation is wrong, or my diagram, can anyone please show me where i am going wrong
thanks!!
Last edited: Dec 5, 2008
2. Dec 5, 2008
### aerospaceut10
I'm a bit confused with your notation, I guess. what is m?
3. Dec 5, 2008
### jmarcian
here is my attempt,
first off, dont forget that you are looking for WEIGHT, which is (mass)(gravity)
ok, if you draw your diagram, you will notice in order for the rod to move, the weight at point r has to be between AP, let's call A=0m and P=1m. Now draw the rods weight, and where it should be placed, in the center of the rod, or W=2m. notice now that the distance from P to the center of the rod must be 1m. since A=0m and W=2m, and since P=1m, the distance from P to W is 1m.
now just set up you equation, i used a variable "a" to represent the moment arm of the point r, but this distance measures rp not ar. but that is easy to solve, let start with the moment equation.
Mp=(3kg)(9.81kg/m2)(a)-(2kg)(9.81kg/m2)(1m)=0
solving for a we get a=2/3m
now remember what i said before a is the moment arm of the point r, measured from p. also remember for the rod to move, r has to be to the left of p. and since AP=1m, and rP=2/3m we arrive at our solution
Ar=1/3m
hopethis helps! this was my first time trying to explain something on this site hehehe
4. Dec 5, 2008
### HallsofIvy
Staff Emeritus
I presume that "xm" means x meters and "3m" means 3 m. But I don't know why you are calculating torque about Q. The problem says it is about to pivot about P, not Q. "AQ=3m" means that the distance from A to Q is 3 meters. Since the stick is 4 meters long that means that the stick has supports 1 meter from each end.
Since the mass of the rod is 2 kg, we can treat that as a downward force 2 m from A. A 3 kg mass is attached at point R, some unknown "x" meters from A.
If "the rod is on the point of turning about point P", the torque in both directions, clockwise and counter clockwise must be the same and the total torque 0 and the upward force at Q must be 0. That means we have only the weight of the rod, 2g N at 1 m from P and the 3g N force at R. Taking "to the right of P" to be positive, we have torque 2g N-m from the weight of the rod and torque 3g(x-1) (since P is itself 1 meter from A). The total torque is 3g(x-1)+ 2g= 0. Solve that for x.
It should be obvious that to offset the weight of the bar to the right of P, R must be to the left of P and x must be less than 1.
5. Dec 5, 2008
### HallsofIvy
Staff Emeritus
One of the things you should have learned from the things you were asked to read when you registered is that you should not give full solutions!
6. Dec 5, 2008
### tweety1234
Hi,
thanks for all your replies but i don't really understand what everyone is saying....
I re-drawn my diagram, if anyone can have a look at it and tell me if it is correct ?
http://www.mathhelpforum.com/math-help/attachments/advanced-applied-math/9103d1228428259-mechanics-help-untitled.jpg [Broken]
from this equation, shouldn't my moments equation be; $$2kg + 3kg (xm-3m)=0$$? (taking moments about P)
Last edited by a moderator: May 3, 2017
7. Dec 5, 2008
### jmarcian
WHOOPS! ill keep that in mind!!
in your drawing, tweety, notice r is not in the appropriate place. becuase having the weight where you placed it would not make the bar rotate about point P, but Q instead...
8. Dec 5, 2008
### tweety1234
Oh right, so should it be next to p instead?
9. Dec 5, 2008
### jmarcian
yes! (in between p and a!)
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Similar Discussions: Help calculation torque, moments. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8594158291816711, "perplexity": 892.3735984357934}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886133447.78/warc/CC-MAIN-20170824082227-20170824102227-00548.warc.gz"} |
http://mathhelpforum.com/math-topics/173634-mechanics-problem-vectors.html | # Math Help - Mechanics Problem - Vectors
1. ## Mechanics Problem - Vectors
A particle has position vector 2i + j initially and is moving with speed 10m/s in the direction 3i - 4j. Find its position vector when t = 3 and the distance it has travelled in those 3 seconds.
My solution:
Position vector = initial position + displacement
since displacement = velocity x time
then position vector= (2i + j) + 3(3i - 4j)
= 2i + j + 9i - 12i
= 11i - 11j
and distance is straightforward, distance = speed x time so 10 x 3 which is 30m.
My solution is however wrong, becuase in the question it says (3i - 4j) is the direction the particle is travelling in, not the velocity, so im kinda stuck and the right answer should be 20i - 23j according to the back of the book.
How do i do this question? Also, if u find the velocity vector, and work out the magnitude, you should get the speed right? So if initial velocity is (2i + 3j) then the magnitude of this vector should equal the speed which is 10 m/s but it does not, the magnitude of this vector is the sqrt (2^2 + 3^2) which is root 13 and not 10 m/s so how does that work? Thanks for you help.
2. Originally Posted by MingMing
A particle has position vector 2i + j initially and is moving with speed 10m/s in the direction 3i - 4j. Find its position vector when t = 3 and the distance it has travelled in those 3 seconds.
My solution:
Position vector = initial position + displacement
since displacement = velocity x time
then position vector= (2i + j) + 3(3i - 4j)
= 2i + j + 9i - 12i
= 11i - 11j
and distance is straightforward, distance = speed x time so 10 x 3 which is 30m.
My solution is however wrong, becuase in the question it says (3i - 4j) is the direction the particle is travelling in, not the velocity, so im kinda stuck and the right answer should be 20i - 23j according to the back of the book.
How do i do this question? Also, if u find the velocity vector, and work out the magnitude, you should get the speed right? So if initial velocity is (2i + 3j) then the magnitude of this vector should equal the speed which is 10 m/s but it does not, the magnitude of this vector is the sqrt (2^2 + 3^2) which is root 13 and not 10 m/s so how does that work? Thanks for you help.
$\displaystyle \vec{s} = \vec{s_0} + \vec{v}t$
Note that 3i - 4j is a vector in the direction of the velocity. It is not the velocity. The velocity will be the unit vector in the direction of 3i - 4j times the speed. Thus
$\displaystyle \vec{v} = \left ( \frac{3i - 4j}{|3i - 4j|} \right ) \cdot 10~\text{m/s}$
-Dan
3. Thank you. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 2, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9331523180007935, "perplexity": 658.7746427554558}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-49/segments/1416931010590.31/warc/CC-MAIN-20141125155650-00213-ip-10-235-23-156.ec2.internal.warc.gz"} |
http://www.epicrapbattlesofhistory.com/video/jqGciPsMFziH/ | # Most Recent Videos
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# Intense Viewer Mail.
nicepetertoo-yt|7:38
# Intense Viewer Mail.
## Published: Mar 12, 2012
Hi. My name is Nice Peter, and this is the Monday Show.
Its very late on Sunday as I type these words, so I'm going to sleep.
see you soon,
- nice peter | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.971737802028656, "perplexity": 25163.1396953189}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-13/segments/1490218189525.23/warc/CC-MAIN-20170322212949-00306-ip-10-233-31-227.ec2.internal.warc.gz"} |
http://www.ionicon.com/publications?qt-main_navigation=2&f%5Bauthor%5D=1706 | Scientific Articles - PTR-MS Bibliography
Welcome to the new IONICON scientific articles database!
Publications
Found 4 results
Title [ Year]
Filters: Author is Taipale, R [Clear All Filters]
2009
[Davison2009] "Concentrations and fluxes of biogenic volatile organic compounds above a Mediterranean macchia ecosystem in western Italy", Biogeosciences, vol. 6: EGU, pp. 1655–1670, 2009.
Abstract
Emission rates and concentrations of biogenic volatile organic compounds (BVOCs) were measured at a Mediterranean coastal site at Castelporziano, approximately 25 km south-west of Rome, between 7 May and 3 June 2007, as part of the ACCENT-VOCBAS field campaign on biosphere–atmosphere interactions. Concentrations and emission rates were measured using the disjunct eddy covariance (DEC) method utilizing three different proton transfer reaction mass spectrometers (PTR-MS) so allowing a comparison between the instruments. The high resolution data from the PTR-MS instruments considerably enhances the original BEMA measurements of the mid 1990s. Depending on the measurement period, the volume mixing ratios were in the range 1.6–3.5 ppbv for methanol, 0.44–1.3 ppbv for acetaldehyde, 0.96–2.1 ppbv for acetone, 0.10–0.14 ppbv for isoprene, and 0.13–0.30 ppbv for monoterpenes. A diurnal cycle in mixing ratios was apparent with daytime maxima for methanol, acetaldehyde, acetone, and isoprene. The fluxes ranged from 370–440 μg m−2 h−1 for methanol, 180–360 μg m−2 h−1 for acetaldehyde, 180–450 μg m−2 h−1 for acetone, 71–290 μg m−2 h−1 for isoprene, and 240–860 μg m−2 h−1 for monoterpenes. From the measured flux data (7 May–3 June) an average basal emission rate for the Macchia vegetation was calculated of 430 μg m−2 h−1 for isoprene and 1100 μg m−2 h−1 for monoterpenes.
[Rinne2009] "Origin of monoterpene emissions from boreal tree species: Determination of de novo and pool emissions by 13CO2 labeling", AGU Fall Meeting Abstracts, vol. 1, pp. 04, 2009.
Abstract
Boreal forests emit a large amount of monoterpenes into the atmosphere. Traditionally these emissions are assumed to originate as evaporation from large storage pools. Thus their diurnal cycle would depend mostly on temperature. However, there is indication that a significant part of the monoterpene emission would originate directly from de novo synthesis. By applying 13CO2 fumigation and analyzing the isotope fractions with proton transfer reaction mass spectrometry (PTR-MS) and classical GC-MS we studied the origin of monoterpene emissions from some major Eurasian boreal and alpine tree species. We determined the fractions originating from de novo biosynthesis and from large internal monoterpene storages for three coniferous tree species with specialized monoterpene storage structures and one dicotyledon species without such structures. The emission from dicotyledon species Betula pendula originated solely from the de novo synthesis. The origin of the emissions from coniferous species was mixed with varying fraction originating from de novo synthesis (Pinus sylvestris 58%, Picea abies 33.5%, Larix decidua 9.8%) and the rest from large internal monoterpene storage pools. Application of the observed fractions of emission originating from de novo synthesis and large storage pools in a hybrid emission algorithm resulted in a better description of ecosystem scale monoterpene emissions from a boreal Scots pine forest stand.
[Ruuskanen2009] "Quantitative long-term measurements of VOC concentrations by PTR-MS: annual cycle at a boreal forest site", Atmospheric Chemistry and Physics Discussions, vol. 9, no. 1: Copernicus GmbH, pp. 81–134, 2009.
2008
[Taipale2008] "Technical Note: Quantitative long-term measurements of VOC concentrations by PTR-MS–measurement, calibration, and volume mixing ratio calculation methods", Atmospheric Chemistry and Physics, vol. 8, no. 22: Copernicus GmbH, pp. 6681–6698, 2008.
Abstract
Proton transfer reaction mass spectrometry (PTR-MS) is a technique for online measurements of atmospheric concentrations, or volume mixing ratios, of volatile organic compounds (VOCs). This paper gives a detailed description of our measurement, calibration, and volume mixing ratio calculation methods, which have been designed for long-term stand-alone field measurements by PTR-MS. The PTR-MS instrument has to be calibrated regularly with a gas standard to ensure the accuracy needed in atmospheric VOC measurements. We introduce a novel method for determining an instrument specific relative transmission curve using information obtained from a calibration. This curve enables consistent mixing ratio calculation for VOCs not present in a calibration gas standard. Our method proved to be practical, systematic, and sensitive enough to capture changes in the transmission over time. We also propose a new approach to considering the abundance of H3O+H2O ions in mixing ratio calculation. The approach takes into account the difference in the transmission efficiencies for H3O+ and H3O+H2O ions. To illustrate the functionality of our measurement, calibration, and calculation methods, we present a one-month period of ambient mixing ratio data measured in a boreal forest ecosystem at the SMEAR II station in southern Finland. During the measurement period 27 March–26 April 2007, the hourly averages of the mixing ratios were 0.051–0.57 ppbv for formaldehyde, 0.19–3.1 ppbv for methanol, 0.038–0.39 ppbv for benzene, and 0.020–1.3 ppbv for monoterpenes. The detection limits for the hourly averages were 0.020, 0.060, 0.0036, and 0.0092 ppbv, respectively.
Featured Articles
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Selected PTR-MS related Reviews
F. Biasioli, C. Yeretzian, F. Gasperi, T. D. Märk: PTR-MS monitoring of VOCs and BVOCs in food science and technology, Trends in Analytical Chemistry 30 (7) (2011).
J. de Gouw, C. Warneke, T. Karl, G. Eerdekens, C. van der Veen, R. Fall: Measurement of Volatile Organic Compounds in the Earth's Atmosphere using Proton-Transfer-Reaction Mass Spectrometry. Mass Spectrometry Reviews, 26 (2007), 223-257. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8718786239624023, "perplexity": 13719.442550252621}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948522343.41/warc/CC-MAIN-20171213084839-20171213104839-00088.warc.gz"} |
https://portlandpress.com/bioscirep/article/4/10/843/55270/Hepatic-hexose-transport-and-the-effect-of | Hepatic hexose transport was characterized using 3-O-methyl-D-glucose, which is not metabolized by the liver. The kinetic parameters determined in the starved state were taken as basal values for the transport system which showed saturation kinetics with high Vmax and Km values of 161 nmol/mg dry wt./rnin and 39 mM respectively. In the fed state, the Vmax was found to be increased nearly two-fold; this may be due to a phenomenon known as trans-stirnulation. The effects of N2-induced anoxia and of KCN were investigated. In the fasted state, anoxia caused the transport characteristics Vmax and Km to decrease nearly two-fold whereas KCN had the opposite effect as the Vmax and Km were increased by three- and two-fold respectively. In the fed state, anoxia and KCN caused a marked decrease in the transport characteristics.
This content is only available as a PDF. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8951057195663452, "perplexity": 4998.698353986859}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-24/segments/1590347390442.29/warc/CC-MAIN-20200526015239-20200526045239-00179.warc.gz"} |
http://math.stackexchange.com/questions/62150/whats-the-simplest-algorithm-for-resizing-an-object-inside-a-rectangle-so-that | # What's the simplest algorithm for resizing an object inside a rectangle so that it's as large as possible?
This is a simple enough problem that I could just cover all corner cases, but I was wondering if there was an elegant way to do this.
Here is the starting point. It finds out which side of the image is taller and then sets that to match up with the size of the "b" boundary. So if it's wider than it is tall it'll set it to be the width of the boundary.
void setBoundsMaxSize(Drawable d, Rect b) {
int bWidth = b.right - b.left + 1;
int bHeight = b.bottom - b.top + 1;
if(d.width() > d.height()) {
// it's wider than it is tall
int newHeight = bWidth * d.height() / d.width();
int padding = (bHeight - newHeight) / 2;
} else {
// the width and height are the same or it's taller than it is wide.
int newWidth = bHeight * d.width() / d.height();
int padding = (bWidth - newWidth) / 2;
}
}
This algorithm works if the "b" boundary is square. However, if it's not then I'll need special cases to check if the newWidth and newHeight are inside the boundary. If they're not then I'll need to shrink it down to fit.
So I'd be handling 4 separate special cases.
I was just curious if there was a cleaner way to deal with this.
EDIT:
FWIW this is what I've got now. It's pretty good, but I still wonder if there's a simple way to know at the beginning that I don't need to try one and then do the other.
public static void setBoundsMaxSize(Drawable d, Rect b) {
if(d.getIntrinsicWidth() > d.getIntrinsicHeight()) {
// it's wider than it is tall
shrinkVert(d,b);
} else {
// the width and height are the same or it's taller than it is wide.
shrinkHoriz(d,b);
}
}
private static void shrinkVert(Drawable d, Rect b) {
int bWidth = b.right - b.left + 1;
int newHeight = bWidth * d.getIntrinsicHeight() / d.getIntrinsicWidth();
int bHeight = b.bottom - b.top + 1;
if(newHeight > bHeight) {
shrinkHoriz(d,b);
} else {
int padding = (bHeight - newHeight) / 2;
}
}
private static void shrinkHoriz(Drawable d, Rect b) {
int bHeight = b.bottom - b.top + 1;
int newWidth = bHeight * d.getIntrinsicWidth() / d.getIntrinsicHeight();
int bWidth = b.right - b.left + 1;
if(newWidth > bWidth) {
shrinkVert(d,b);
} else {
int padding = (bWidth - newWidth) / 2;
}
}
-
The 'minimum bounding rectangle' problem is very close to your problem en.wikipedia.org/wiki/Minimum_bounding_box_algorithms assuming your object is a convex polygon then the minimum bounding rectangle and the convex polygon will have a parallel side. (Just throwing that out there) – Peter Sheldrick Sep 6 '11 at 6:14
if (d.width / d.height > b.width / b.height) { | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.24219152331352234, "perplexity": 611.7216539320576}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-42/segments/1413507448169.17/warc/CC-MAIN-20141017005728-00029-ip-10-16-133-185.ec2.internal.warc.gz"} |
http://mdolab.engin.umich.edu/Biblio?f%5Bkeyword%5D=6&f%5Bauthor%5D=318&s=year&o=asc | Publications
Export 1 results:
Author Keyword Title Type [ Year]
Filters: Keyword is AD and Author is Juan J. Alonso [Clear All Filters]
2007
, A methodology for the development of discrete adjoint solvers using automatic differentiation tools, International Journal of Computational Fluid Dynamics, vol. 21, pp. 307-327, 2007. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8099547624588013, "perplexity": 2445.2719445968214}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-24/segments/1590347407289.35/warc/CC-MAIN-20200530040743-20200530070743-00178.warc.gz"} |
http://web.stanford.edu/group/wang_group/People/Amal_El-Ghazaly.html | About Amal's research on Integrated Transformers for Efficient Power Conversion:
This project aims to extend the efficiency and isolation of transformer-based power conversion to widespread applications. Through the integration of thin-film magnetic cores, transformers can be taken from macroscopic, lumped element use to being implemented on-chip and incorporated into both AC-to-DC and DC-to-DC power conversion. While the most significant source of loss for transformer designs arises from coupling loss, we have previously demonstrated transformers with an unprecedented value of greater than 97% coupling efficiency. Additional factors limiting the efficiency of specifically magnetic transformers consist of material losses, including hysteresis loss, eddy current loss, and ferromagnetic resonance loss. Hysteresis loss is proportional to the area inside the B-H loop and equates to energy lost per cycle, potentially leading to significant losses at higher frequencies. To limit hysteresis loss, materials with low coercivities are desired, reducing the overall area of the B-H loop and the energy lost per cycle. As a field is applied to magnetize the material, small currents arise in the cross-section to produce an opposing field. These eddy currents thereby decrease the effect of the applied field. Eddy currents can be minimized in two ways, through the use of more resistive materials as well as laminations, which break apart the thickness of the cores and reduce the currents in the cross-section. As with the first two loss mechanisms, ferromagnetic resonance loss also increases with frequency when the imaginary part of the permeability rises to the same order of magnitude as the real part. Magnetic materials with a high ferromagnetic resonance frequency (FMR) are desired to mitigate the FMR losses. In order to address these material losses, magnetic nanoparticles will be synthesized to produce the desired properties tuned for the most efficient magnetic cores. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8313753008842468, "perplexity": 1189.364828085556}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-35/segments/1409535922871.14/warc/CC-MAIN-20140901014522-00350-ip-10-180-136-8.ec2.internal.warc.gz"} |
http://www.ck12.org/geometry/Midpoints-and-Segment-Bisectors/exerciseint/True-or-False--Is-This-the-Midpoint/r1/ | <img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
# Midpoints and Segment Bisectors
## Midpoints and bisectors can be used to find the halfway mark between two coordinates.
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Progress
Practice Midpoints and Segment Bisectors
Progress
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True or False--Is This the Midpoint
Teacher Contributed
The midpoint of the line joining (2, 4) and (6, 8) is (-2.0, -2.0).
qid: 100125 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8790639042854309, "perplexity": 16715.665321911336}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-48/segments/1448398461132.22/warc/CC-MAIN-20151124205421-00056-ip-10-71-132-137.ec2.internal.warc.gz"} |
https://tex.stackexchange.com/questions/462433/draw-a-line-not-touching-edges/462446 | # Draw a line not touching edges
I'm drawing a line between 2 nodes and I'd like to avoid to touch the nodes, I have been able to do it with the first node but not with the second.
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\begin{document}
\tikzstyle{every picture}+=[remember picture]
\tikz[baseline] \node[fill opacity=0.1,circle,label=left:2016,fill=black,inner sep=3pt] at (0,0) (n1) {};
\tikz[baseline] \node[draw=none,fill=none,align=left] {
\vbox{
bar
}
};
\tikz[baseline] \node[draw=none,align=left] {
\hspace*{20mm}\parbox{10cm}{
foo
}
};
\tikz[baseline] \node[fill opacity=0.1,circle,label=left:2016,fill=black,inner sep=3pt] at (0,0) (n2) {};
\tikz[baseline] \node[draw=none,fill=none,align=left] {
\vbox{
bar
}
};
\tikz[baseline] \node[draw=none,align=left] {
\hspace*{20mm}\parbox{10cm}{
foo
}
};
\begin{tikzpicture}[overlay]
\draw (n1)++(0, -0.25) -- (n2)++(0, 0.25);
\end{tikzpicture}
\end{document}
https://www.overleaf.com/project/5c00283f4365993602702d4f
• Try \draw ([yshift=-0.1cm]n1.south) -- ([yshift=0.1cm]n2.north);. (And replace \tikzstyle{every picture}+=[remember picture] by \tikzset{every picture/.append style={remember picture}}) Not sure if I would draw this picture in the way you do, why don't you just draw one picture? – user121799 Nov 29 '18 at 18:25
• It works nicely, thanks again @marmot. I also replaced the section you mentioned. I'm not using one picture because I'm mixing text and a few nodes, if I used \begin{tikzpicture} It would not allow me to use some commands. Probably because I do not know Latex – Rod Nov 29 '18 at 18:35
In your setting, you'd only need to use \draw ([yshift=-0.1cm]n1.south) -- ([yshift=0.1cm]n2.north);. However, one can draw your picture in a single picture without remember picture.
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}
\node[fill opacity=0.1,circle,label=left:2016,fill=black,inner
sep=3pt,label={[xshift=5mm]right:bar},label={[xshift=2mm,yshift=-5mm]right:foo},] (N1){};
\node[below=1cm of N1,fill opacity=0.1,circle,label=left:2016,fill=black,inner
sep=3pt,label={[xshift=5mm]right:bar},label={[xshift=2mm,yshift=-5mm]right:foo}] (N2) {};
\draw ([yshift=-0.1cm]N1.south) -- ([yshift=0.1cm]N2.north);
\end{tikzpicture}
\end{document}
ADDENDUM: Using Zarko's way to define a universal style, one could use outer sep to produce the gaps. I would rather not use shorten as this can have unwanted side-effects if you consider using curved paths.
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}[pfft/.style={circle,fill opacity=0.1,fill=black,inner
sep=3pt,outer sep=1mm}]
\node[pfft,label=left:2016,,label={[xshift=5mm]right:bar},label={[xshift=2mm,yshift=-5mm]right:foo},] (N1){};
\node[below=1cm of N1,pfft,label=left:2016,label={[xshift=5mm]right:bar},label={[xshift=2mm,yshift=-5mm]right:foo}] (N2) {};
\draw (N1) -- (N2);
\end{tikzpicture}
\end{document}
• When did shorten get deprecated? It is still used in the examples in the 3.0.1a manual. – Peter Grill Nov 29 '18 at 19:52
• @PeterGrill I do not think it got officially deprecated. However, it can cause issues on curved paths, see e.g. here. So I do not see that it is better than the yshift solution, rather it can backfire. – user121799 Nov 29 '18 at 19:56
And a third option, without yshift and without outer sep but shorten option in line between nodes:
\documentclass[tikz, margin=3.141592mm]{standalone}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}[
node distance = 12mm,
dot/.style = {circle, fill=black, fill opacity=0.1,
inner sep=3pt, %No outer sep like in Zarko's answer
node contents={}}
]
\node (n1) [dot, label=left:2016, label={[xshift=3mm]right:bar}, label=below right:foo];
\node (n2) [dot, label=left:2017, label={[xshift=3mm]right:bar}, label=below right:foo,
below=of n1];
\draw[shorten >=2pt, shorten <=2pt] (n1) -- (n2); %No yshift like in Marmot's answer
\end{tikzpicture}
\end{document}
as complement to nice @marmot answer:
\documentclass[tikz, margin=3.141592mm]{standalone}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}[
node distance = 12mm,
dot/.style = {circle, fill=black, fill opacity=0.1,
inner sep=3pt, outer sep=2pt,
node contents={}}
]
\node (n1) [dot, label=left:2016, label={[xshift=3mm]right:bar}, label=below right:foo];
\node (n2) [dot, label=left:2017, label={[xshift=3mm]right:bar}, label=below right:foo,
below=of n1];
\draw (n1) -- (n2);
\end{tikzpicture}
\end{document} | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9405468106269836, "perplexity": 9545.384252253803}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570986692126.27/warc/CC-MAIN-20191019063516-20191019091016-00490.warc.gz"} |
http://mathhelpforum.com/algebra/94393-gre-question.html | 1. GRE Question
If 0 < st < 1, then which of the following can be true?
a.) s < -1 and t > 0
b.) s < -1 and t < -1
c.) s > -1 and t < -1
d.) s > 1 and t < -1
e.) s > 1 and t > 1
If s > -1, that means s = 0, 1, 2, ...
If t < -1, that means t = -2, -3, ...
2. Originally Posted by Ideasman
If 0 < st < 1, then which of the following can be true?
a.) s < -1 and t > 0
b.) s < -1 and t < -1
c.) s > -1 and t < -1
d.) s > 1 and t < -1
e.) s > 1 and t > 1
If s > -1, that means s = 0, 1, 2, ...
If t < -1, that means t = -2, -3, ...
first note the wording of the question.
no way any of the other choices will work, no matter what numbers you pick for s and t that meet the given restrictions.
don't limit yourself to integer values.
for (c) ... let s = -1/5 and t = -2
3. They should specify that it's all reals then and not just integers!
Thanks.
4. Originally Posted by Ideasman
They should specify that it's all reals then and not just integers!
Thanks.
where does the question state that only integral values should be used?
5. His point appears to be that "numbers" automatically means integers. After all, he is taking the GRE so he has only had 12 years of school and 4 years of college. You can't expect him to have worked with fractions or irrational numbers in that little time!
Frankly, I'm surprised he didn't complain that they didn't specifically tell him that the test is in English! Otherwise how can he be sure what "of" and "the" mean? | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8182045221328735, "perplexity": 894.4766495388487}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-17/segments/1492917122992.88/warc/CC-MAIN-20170423031202-00461-ip-10-145-167-34.ec2.internal.warc.gz"} |
http://mathhelpforum.com/math-challenge-problems/83022-some-special-polynomials-print.html | # # Some special polynomials!
Let $p$ be a prime number. How many polynomials $f(x) \in \mathbb{F}_p[x]$ of degree at most $p-1$ are there for which the map $a \longmapsto f(a)$ is a permutation of $\mathbb{F}_p$? | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 5, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9734519720077515, "perplexity": 63.833609723614664}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-18/segments/1461861700245.92/warc/CC-MAIN-20160428164140-00160-ip-10-239-7-51.ec2.internal.warc.gz"} |
https://ai.stackexchange.com/questions/2733/understanding-why-the-expectation-is-over-the-new-policy-pi-in-the-proof-of | # Understanding why the expectation is over the new policy $\pi'$ in the proof of the Policy Improvement Theorem
In reinforcement learning, policy improvement is a part of an algorithm called policy iteration, which attempts to find approximate solutions to the Bellman optimality equations.
Pages 84 and 85 in Sutton and Barto's book on RL mentions the following theorem:
Policy Improvement Theorem
Given two deterministic policies $$\pi$$ and $$\pi'$$, then $$v_\pi(s) \leq q_\pi(s, \pi'(s)), \forall s \in S.$$
where $$S$$ is the set of all states.
In the the right-hand side of the inequality, the agent acts according to policy $$\pi'$$ (given that $$\pi'(s)$$ is used in the inequality), in the current state $$s$$, and for all subsequent states acts according to policy $$\pi$$.
In the left-hand side of the inequality, the agent acts according to policy $$\pi$$ (hence the subscript $$_\pi$$ of $$v_\pi(s)$$), starting from the current state $$s$$.
The claim is the following
$$v_\pi(s) \leq v_{\pi'}(s), \forall s \in S$$
In other words, $$\pi'$$ is is an improvement over $$\pi$$.
However, I have a difficulty in understanding the proof. This is discussed below.
Proof
$$v_\pi(s) \leq q_\pi(s, \pi'(s)) = \mathbb{E}_{\pi'}[R_{t+1} + \gamma v_\pi(S_{t+1}) \mid S_t = s]$$
I am stuck here. The q-function is evaluated over the policy $$\pi$$ (note the subscript $$_\pi$$ in $$q_\pi(s, \pi'(s))$$). That being the case, how is the expectation over the policy $$\pi'$$?
My guess is the following. In the proof given in Sutton and Barto, the expectation is unrolled in time. At each time step, the agent follows the policy $$\pi'$$ for that particular time step, and then follows $$\pi$$ from then on. In the limit of this process, the policy transforms from $$\pi$$ to $$\pi'$$. As long as the expression for the return inside the expectation is finite, the governing policy should be $$\pi$$; only in the limit of this process does the governing policy transform to $$\pi'$$.
The expectation is over the policy $$\pi'$$ because the action at the state $$S_t = s$$ is taken according to $$\pi'$$, and, for the proof, the book text (2nd edition, paragraph below Equation 4.8) defines $$\pi'$$ to be a policy that is identical to $$\pi$$ except that $$\pi'(s) = a \neq \pi(s)$$, where $$s$$ is one particular state.
So, essential, the book text tries to prove that, for such a changed policy $$\pi'$$, if $$q_\pi(s, a) = q_\pi(s, \pi'(s)) > v_\pi(s)$$, then the changed policy is better than $$\pi$$. Note that $$\pi'(s) = a$$ in this case.
That is why $$q_\pi(s, \pi'(s)) = \mathbb{E}_{\pi'}[R_{t+1} + \gamma v_\pi(S_{t+1}) \mid S_t = s]$$. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 38, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7273640036582947, "perplexity": 188.71297647518006}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-17/segments/1618038072366.31/warc/CC-MAIN-20210413122252-20210413152252-00336.warc.gz"} |
https://blogdacrianca.com/2fufaf/constrained-recursive-least-squares-a8627b | time-series consisting of a nonlinear function of the true but unknown parameter corrupted by noise. Recursive least squares (RLS) corresponds to expanding window ordinary least squares (OLS). 0000004725 00000 n 22 0 obj <> endobj 0000001606 00000 n 0000121652 00000 n It is also a crucial piece of information for helping improve state of charge (SOC) estimation, health prognosis, and other related tasks in the battery management system (BMS). 0000131365 00000 n 0000001834 00000 n A Recursive Least Squares Implementation for LCMP Beamforming Under Quadratic Constraint Zhi Tian, Member, IEEE, Kristine L. Bell, Member, IEEE, and Harry L. Van Trees, Life Fellow, IEEE Abstract— Quadratic constraints on the weight vector of an adaptive linearly constrained minimum power (LCMP) beam- ... also includes time‐varying parameters that are not constrained by a dynamic model. Hong, X. and Gong, Y. (2) Choose a forgetting factor 0 < λ ≤ 1. Hong, X. and Gong, Y. The derivations make use of partial … References * Durbin, James, and Siem Jan Koopman. Linear least squares problems which are sparse except for a small subset of dense equations can be efficiently solved by an updating method. 0000015143 00000 n Unlike information-type algorithms, covariance algorithms are amenable to parallel implementation, e.g., on processor arrays, and this is also demonstrated. In this paper, we develop a novel constrained recursive least squares algorithm for adaptively combining a set of given multiple models. Distributed Recursive Least-Squares: Stability and Performance Analysis ... of inexpensive sensors with constrained resources cooperate to achieve a common goal, constitute a promising technology for applications as diverse and crucial as environmental monitor-ing, process control and fault diagnosis for the industry, … Download PDF Abstract: In this paper, we propose a new {\it \underline{R}ecursive} {\it \underline{I}mportance} {\it \underline{S}ketching} algorithm for {\it \underline{R}ank} constrained least squares {\it \underline{O}ptimization} (RISRO). %PDF-1.7 %���� The Recursive Least Squares (RLS) approach [25, 15] is an instantiation of the stochastic Newton method by replacing the scalar learning rate with an approximation of the Hessian … 0000006846 00000 n In: 2015 International Joint Conference on Neural Networks (IJCNN), 12-17, July, 2015, Killarney, Ireland. 64 0 obj <>stream 0000090204 00000 n It offers additional advantages over conventional LMS algorithms such as faster convergence rates, modular structure, and insensitivity to variations in eigenvalue spread of the input … The NLMS algorithm can be summarised as: ... Recursive least squares; For statistical techniques relevant to LMS filter see Least squares. However, employing the The expression of (2) is an exact solution for the con-strained LS problem of interest, (1). 0000140756 00000 n 0000014736 00000 n Then a weighted l2-norm is applied as an approximation to the l1-norm term. ALGLIB for C++,a high performance C++ library with great portability across hardwareand software platforms 2. It is important to generalize RLS for generalized LS (GLS) problem. 0000001648 00000 n It is advisable to refer to the publisher's version if you intend to cite from this work. Apart from using Z t instead of A t, the update in Alg.4 line3 conforms with Alg.1 line4. startxref 0000015419 00000 n The constrained 0000016735 00000 n 0000009500 00000 n Time Series Analysis by State Space Methods: Second … 0 The method of weighting is employed to incorporate the linear constraints into the least-squares problem. The results of constrained and unconstrained parameter estimation are presented The linear least mean squares (LMS) algorithm has been recently extended to a reproducing kernel Hilbert space, resulting in an adaptive filter built from a weighted sum of kernel functions evaluated at each incoming data sample. CONTINUOUS-TIME CONSTRAINED LEAST-SQUARES ALGORITHMS FOR RECURSIVE PARAMETER ESTIMATION OF STOCHASTIC LINEAR SYSTEMS BY A STABILIZED OUTPUT ERROR METHOD A.J. ALGLIB for C#,a highly optimized C# library with two alternati… 0000003312 00000 n Recursive Least Squares. Distributed Constrained Recursive Nonlinear Least-Squares Estimation: Algorithms and Asymptotics Anit Kumar Sahu, Student Member, IEEE, Soummya Kar, Member, IEEE, Jose M. F. Moura,´ Fellow, IEEE and H. Vincent Poor, Fellow, IEEE Abstract This paper focuses on recursive nonlinear least squares parameter estimation in multi … As … the least squares problem. • The concept of underdetermined recursive least-squares filtering is introduced from first principles to fill the gap between normalized least mean square (NLMS) and recursive least squares (RLS) algorithms and defined formally, which has been lacking up to now. Least squares (LS)optimiza-tion problems are those in which the objective (error) function is a quadratic function of the parameter(s) … University Staff: Request a correction | Centaur Editors: Update this record, http://dx.doi.org/10.1109/IJCNN.2015.7280298, School of Mathematical, Physical and Computational Sciences. This paper shows that the unique solutions to linear-equality constrained and the unconstrained LS problems, respectively, always have exactly the same recursive form. Abstract: We develop a new linearly-constrained recursive total least squares adaptive filtering algorithm by incorporating the linear constraints into the underlying total least squares problem using an approach similar to the method of weighting and searching for the solution (filter weights) along the input vector. At each time step, the parameter estimate obtained by a recursive least squares estimator is orthogonally projected onto the constraint surface. 0000003024 00000 n In contrast, the constrained part of the third algorithm preceeds the unconstrained part. The Lattice Recursive Least Squares adaptive filter is related to the standard RLS except that it requires fewer arithmetic operations (order N). This paper shows that the unique solutions to linear-equality constrained and the unconstrained LS problems, respectively, always have exactly the same recursive … Linear and nonlinear least squares fitting is one of the most frequently encountered numerical problems.ALGLIB package includes several highly optimized least squares fitting algorithms available in several programming languages,including: 1. A battery’s capacity is an important indicator of its state of health and determines the maximum cruising range of electric vehicles. 0000131838 00000 n A distributed recursive … 0000003789 00000 n 0000090442 00000 n 22 43 Moreover an l1-norm constraint to the combination parameters is also applied with the aim to achieve sparsity of multiple models so that only a subset of models may be selected into the final model. 0000004165 00000 n (2015) It is shown that this algorithm gives an exact solution to a linearly constrained least-squares adaptive filtering problem with perturbed constraints and … Nearly all physical systems are nonlinear at some level, but may appear linear over … 0000001998 00000 n Full text not archived in this repository. 3.1 Recursive generalized total least squares (RGTLS) The herein proposed RGTLS algorithm that is shown in Alg.4, is based on the optimization procedure (9) and the recursive update of the augmented data covariance matrix. 2012. It is applicable for problems with a large number of inequalities. 0000006463 00000 n <]>> 2) You may treat the least squares as a constrained optimization problem. (2015) A constrained recursive least squares algorithm for adaptive combination of multiple models. 0000004994 00000 n This model applies the Kalman filter to compute recursive estimates of the coefficients and recursive residuals. 0000004052 00000 n With data available in an online fashion, the linear combination coefficients of submodels are adapted via the proposed algorithm.We propose to minimize the mean square error with a forgetting factor, and apply the sum to one constraint to the combination parameters. 0000017800 00000 n As in any other problem of this kind, you have the cost function defined in a … The proposed algorithm outperforms the previously proposed constrained … xref 0000013576 00000 n 0000002859 00000 n Udink ten Cate September 1 98 5 WP-85-54 Working Papers are interim reports on work of the International Institute for … 0000091546 00000 n It is also of value to … trailer (3) Get new … Often the least squares solution is also required to satisfy a set of linear constraints, which again can be divided into sparse and dense subsets. 3.3. %%EOF Summary of the constrained recursive least squares (CRLS) subspace algorithm (1) Use the CLS subspace algorithm in Section 2 to initialize the parameter vector θ ˆ N f and covariance P ˆ N from a set {u 0, y 0, ⋯ , u N−1, y N−1} of N input–output data. This chapter discusses extensions of basic linear least ‐ squares techniques, including constrained least ‐ squares estimation, recursive least squares, nonlinear least squares, robust estimation, and measurement preprocessing. • Fast URLS algorithms are derived. The normal equations of the resultant unconstrained least-squares … 0000002134 00000 n 0000013710 00000 n 0000001512 00000 n x�bf`y�������A��X��,S�f��"L�ݖ���p�z&��)}~B������. 0000012195 00000 n As such at each time step, a closed solution of the model combination parameters is available. 0000010853 00000 n This paper proposes a novel two dimensional recursive least squares identification method with soft constraint (2D-CRLS) for batch processes. Abstract: A linearly-constrained recursive least-squares adaptive filtering algorithm based on the method of weighting and the dichotomous coordinate descent (DCD) iterations is proposed. Recursive least squares (RLS) estimations are used extensively in many signal processing and control applications. 0000057855 00000 n A constrained recursive least squares algorithm for adaptive combination of multiple models. 0000161600 00000 n Official URL: http://dx.doi.org/10.1109/IJCNN.2015.7280298. 0000114130 00000 n 0000001156 00000 n 0000006617 00000 n In: 2015 International Joint Conference on Neural Networks (IJCNN), 12-17, July, 2015, Killarney, Ireland. The matrix-inversion-lemma based recursive least squares (RLS) approach is of a recursive form and free of matrix inversion, and has excellent performance regarding computation and memory in solving the classic least-squares (LS) problem. In this paper we consider RLS with sliding data windows involving multiple (rank k) updating and downdating computations.The least squares estimator can be found by solving a near-Toeplitz matrix system at each … 0000131627 00000 n These constraints may be time varying. Full text not archived in this repository. The contribution of this paper is to derive the proposed constrained recursive least squares algorithm that is computational efficient by exploiting matrix theory. A new recursive algorithm for the least squares problem subject to linear equality and inequality constraints is presented. The Normalised least mean squares filter (NLMS) is a variant of the LMS algorithm that solves this problem by normalising with the power of the input. The algorithm combines three types of recursion: time-, order-, and active-set-recursion. The constrained recursive least-squares (CRLS) algorithm [6] is a recursive calculation of (2) that avoids the matrix inversions by apply-ing the matrix inversion lemma [15]. 0000004462 00000 n Abstract. adshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A ... present the proposed constrained recursive esti-mation method. Parameter estimation scheme based on recursive least squares can be regarded as a form of the Kalman –lter (Astrom and Wittenmark, 2001). This simple idea, when appropriately executed, enhances the output prediction accuracy of estimated parameters. 0000171106 00000 n The effectiveness of the approach has been demonstrated using both simulated and real time series examples. In this paper, we propose an improved recursive total least squares … We develop a new linearly-constrained recursive total least squares adaptive filtering algorithm by incorporating the linear constraints into the underlying total least squares problem using an approach similar to the method of weighting and searching for the solution (filter weights) along the input vector. See Guidance on citing. For each of the five models the batch solutions and real‐time sequential solutions are provided. Recursive Least Squares (RLS) algorithms have wide-spread applications in many areas, such as real-time signal processing, control and communications. Alfred Leick Ph.D. Department of Geodetic Science, Ohio State University, USA. This paper focuses on the problem of recursive nonlinear least squares parameter estimation in multi-agent networks, in which the individual agents observe sequentially over time an independent and identically distributed (i.i.d.) As its name suggests, the algorithm is based on a new sketching framework, recursive … In this contribution, a covariance counterpart is described of the information matrix approach to constrained recursive least squares estimation. 0000008153 00000 n 0000000016 00000 n The proposed algorithm outperforms the previously proposed constrained recursive least … The Least Mean Squares (LMS) algorithm [25] is the standard first order SGD, which takes a scalar as the learning rate. Similarities between Wiener … This method can improve the identification performance by exploiting information not only from time direction within a batch but also along batches. Least Squares Optimization The following is a brief review of least squares optimization and constrained optimization techniques,which are widely usedto analyze and visualize data. Recursive Least Squares (RLS) algorithms have wide-spread applications in many areas, such as real-time signal processing, control and communications.
2020 constrained recursive least squares | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7787994146347046, "perplexity": 1150.6825025880385}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-04/segments/1610703495936.3/warc/CC-MAIN-20210115164417-20210115194417-00010.warc.gz"} |
https://ask.sagemath.org/question/39202/laurent-series-error-q2oq-is-not-oq/ | # Laurent series error q^2+O(q) is not O(q) edit
I get an error for the following code:
R.<q>=LaurentSeriesRing(QQ,1)
O(q)+q^2
Any explanation? (works for PowerSeriesRing) Here is the error:
Error in lines 2-2 Traceback (most recent call last): File "/cocalc/lib/python2.7/site-packages/smc_sagews/sage_server.py", line 996, in execute exec compile(block+'\n', '', 'single') in namespace, locals File "", line 1, in <module> File "sage/structure/element.pyx", line 1192, in sage.structure.element.Element.__add__ (/ext/sage/sage-8.0/src/build/cythonized/sage/structure/element.c:10640) return (<element>left)._add_(right) File "sage/rings/laurent_series_ring_element.pyx", line 622, in sage.rings.laurent_series_ring_element.LaurentSeries._add_ (/ext/sage/sage-8.0/src/build/cythonized/sage/rings/laurent_series_ring_element.c:8637) return right.add_bigoh(self.prec()) File "sage/rings/laurent_series_ring_element.pyx", line 691, in sage.rings.laurent_series_ring_element.LaurentSeries.add_bigoh (/ext/sage/sage-8.0/src/build/cythonized/sage/rings/laurent_series_ring_element.c:9742) u = self.__u.add_bigoh(prec - self.__n) File "sage/rings/power_series_ring_element.pyx", line 797, in sage.rings.power_series_ring_element.PowerSeries.add_bigoh (/ext/sage/sage-8.0/src/build/cythonized/sage/rings/power_series_ring_element.c:9029) return self._parent(v, prec) File "sage/structure/parent.pyx", line 936, in sage.structure.parent.Parent.__call__ (/ext/sage/sage-8.0/src/build/cythonized/sage/structure/parent.c:9826) return mor._call_with_args(x, args, kwds) File "sage/structure/coerce_maps.pyx", line 173, in sage.structure.coerce_maps.DefaultConvertMap_unique._call_with_args (/ext/sage/sage-8.0/src/build/cythonized/sage/structure/coerce_maps.c:5322) raise File "sage/structure/coerce_maps.pyx", line 166, in sage.structure.coerce_maps.DefaultConvertMap_unique._call_with_args (/ext/sage/sage-8.0/src/build/cythonized/sage/structure/coerce_maps.c:5161) return C._element_constructor(x, *args) File "/ext/sage/sage-8.0/local/lib/python2.7/site-packages/sage/rings/power_series_ring.py", line 783, in _element_constructor_ raise ValueError("prec (= %s) must be non-negative" % prec) ValueError: prec (= -1) must be non-negative
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What is the expectation?
Default precision has an other sense here... For instance:
sage: R.<q>=LaurentSeriesRing(QQ, default_prec=10)
sage: R(q^100)
q^100
sage: R(q^100)/R(1+q)
q^100 - q^101 + q^102 - q^103 + q^104 - q^105 + q^106 - q^107 + q^108 - q^109 + O(q^110)
sage: R(q^-100)/R(1+q)
q^-100 - q^-99 + q^-98 - q^-97 + q^-96 - q^-95 + q^-94 - q^-93 + q^-92 - q^-91 + O(q^-90)
The word default precision tells just how many significant terms should be computed and shown. It is not about an ideal, computations may show O(q^110) . Which is not O(q^10).
The initialization of an element of the ring is an other story, and sage assume the user knows what makes sense, and what not.
So q^2 + O(q) simply makes no sense. The error ValueError: prec (= -1) must be non-negative is telling enough. Same for q^2017 + O(q) where the error is of course ValueError: prec (= -2016) must be non-negative.
more
The expectation is O(q). The same code works for power series and gives the desired result O(q)
( 2017-10-19 16:08:25 +0200 )edit
OK, right, this should not happen.
But there is a good way to prevent thing going wrong like the above. Simply use
R.<q>=LaurentSeriesRing(QQ, default_prec=10)
a = R(q^2)
and there is no problem to work inside this ring. For instance:
sage: a
q^2
sage: a.precision_absolute()
+Infinity
sage: a.precision_relative()
+Infinity
The big problem i see is related to a bug (rather than feature) in the function add_bigoh, which crashes in a.add_bigoh(1) or in (a^3).add_bigoh(5) ... I think it is simple to fix the code. (I would fix it, but am still new in sage devel, no git use so far...)
Thanks for the post!
( 2017-10-23 22:45:45 +0200 )edit
Sorry, I don't really understand your way of preventing. I showed a simple example of how things can go wrong, which makes computations in Laurent series rings impossible because you can't even perform addition in there. For example,
a=R(1+q+O(q^2))
b=R(-1-q-O(q^4))
c=R(q^3+O(q^4))
print a+b+c
gives an error. I think you are right about the function add_bigoh. I tried to understand how to report bugs in here, but it seems overly complicated tbh, so if you or anyone could report that, it would be great! Also, it just seems that the whole LaurentSeriesRing is underdeveloped (earlier I asked about lifting homomorphisms from the base ring to Laurent series, which is implemented for polynomials but not for series),which is weird because Laurent series are better than power
( 2017-10-24 01:22:34 +0200 )edit | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.2545047104358673, "perplexity": 5367.5348965547455}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243989012.26/warc/CC-MAIN-20210509183309-20210509213309-00445.warc.gz"} |
https://stats.stackexchange.com/questions/185159/selecting-best-arima-model-with-regressors-and-dummy-variable | # Selecting best ARIMA model with regressors and dummy variable
I have data on GDP, employment rate, inflation and production on two countries and I like to make some ARIMA models. I have done this before, but not with including regressors. Also, the time period includes the European crisis, so I created a dummy for this period. I know that I can select the best ARIMA model by checking the AIC and BIC values. But I have to play around with the regressors, maybe it is better not to include them all. Also, I have to check if the dummy is necessary to include or not (Chow test). How do I start?
I thought
1. First, I select the appropriate ARIMA model (using AIC and BIC), using all regressors, but not the dummy.
2. Then, when looking at the significance of the regressors, select the one to use and which not (how to do?).
3. Then compare this model with the same model including the dummy and perform a Chow test on whether to include it or not.
But I feel like there are many more combinations of regressors and the dummy and so on, like I did not test all possible models. What is the right approach?
• You have neither commented, upvoted nor accepted any of the answers (in which we put some effort). Is there something you still would like us to address? – Richard Hardy Feb 10 '17 at 10:55
One idea would be to first compute an ARIMA model without any regressors (using the usual AIC, BIC etc) and then check, if the residuals of this ARIMA model are correlated with your regressors. You could then select those regressors with "significant" correlation (or those whose correlation is higher than a pre-defined threshold) and re-compute the ARIMA model, this time including the regressors.
One drawback of this procedure is that you are, in effect, applying a kind of "hillclimbing" method. So, you are excluding regressors, which are correlated only in (non-linear) combination with another regressor. Nonetheless, the procedure might give you a good starting point for further investigation.
Finally, of course, you should check, if the AIC and BIC values have improved by including the regressors.
The drawback with your approach is that endogeneity among variables and lagged effects are not properly accounted for.
Since these macroeconomic variables are likely to be mutually endogenous and influence each other with some time lags, a VAR or VARMA model would make sense. VAR would be the simpler and more popular alternative; it is often used for modelling the macroeconomic indicators you have. In a VAR model you would select the lag order using information criteria or residual diagnostics. In R the relevant package would be "vars" and function VARselect.
Vector error correction model (VECM; it is a special case of VAR) could be relevant if your variables are cointegrated. After selecting the lag order for a VAR model in levels, you would proceed with cointegration analysis (function ca.jo from package "urca") and VECM modelling.
Regarding inclusion/exclusion of the crisis dummy, you could compare values of information criteria and do residual diagnostics, similarly to when doing lag order selection.
Some relevant references: | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.32567641139030457, "perplexity": 1140.3054789056423}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-16/segments/1585370506870.41/warc/CC-MAIN-20200402080824-20200402110824-00421.warc.gz"} |
https://forum.allaboutcircuits.com/threads/help-too-many-dmms-kits-to-chose-from.606/ | # Help Too many DMMs/kits to chose from
#### darkplayer
Joined Nov 8, 2004
4
Waz up ladies & gent's B)
As the description to my title states, I'm trying to set up my own personal work bench in my apartment. I've just started modding hardwares internally & externally and now I find myself troubleshooting dead circuit boards. I was hoping if you kind people can suggest what type of inexpesive testing equipment & kits I should have.
Items I have:
Hakku 963 soldering station
old analog meter
PC tool kit, basic stuff
Items I need or like to have
DMM, hand held for now
Workbench, probably make my own from Lowes/home depot
Matt for the bench
Kits you think I should have, even a project for a beginner
Thanks.
#### mozikluv
Joined Jan 22, 2004
1,435
hi,
how about logic probe & pulser, signal tracer & injector for a start.
#### darkplayer
Joined Nov 8, 2004
4
Originally posted by mozikluv@Nov 8 2004, 07:19 PM
hi,
how about logic probe & pulser, signal tracer & injector for a start.
[post=3474]Quoted post[/post]
Thanks, already searching for a good deal online Any recommendations on DMM? Looking @ a few w/ diode & transistor test, Cat I/II so far their in the $60 range. #### mozikluv Joined Jan 22, 2004 1,435 hi, you can make your own diode and transistor tester if you like. i made one and i got it from the net, i just made some modification for better performance. if you like i can post the schem. #### m4yh3m Joined Apr 28, 2004 186 Originally posted by mozikluv@Nov 10 2004, 02:26 AM hi, you can make your own diode and transistor tester if you like. i made one and i got it from the net, i just made some modification for better performance. if you like i can post the schem. [post=3493]Quoted post[/post] I am interested in seeing this schematic... could you please post? Thread Starter #### darkplayer Joined Nov 8, 2004 4 Originally posted by mozikluv@Nov 9 2004, 11:26 PM hi, you can make your own diode and transistor tester if you like. i made one and i got it from the net, i just made some modification for better performance. if you like i can post the schem. [post=3493]Quoted post[/post] Can you post both the schem & the actual tester? UPDATE: Just bought a crafstman DMM w/ PC interface for about$46, including shipping & 2 logic probe w/ pulser on Ebay for \$24. Can't wait to get them.
Decided that I or have someone build a small work bench to fit in my room. Unless someone knows where I can get one that's already assembled or can be easily assembled.
#### mozikluv
Joined Jan 22, 2004
1,435
hi,
here's the scr, diode & transistor tester | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.22767478227615356, "perplexity": 10743.772439187873}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652662517245.1/warc/CC-MAIN-20220517095022-20220517125022-00126.warc.gz"} |
https://artofproblemsolving.com/wiki/index.php?title=2021_AMC_12B_Problems/Problem_7&diff=145536&oldid=145531 | # Difference between revisions of "2021 AMC 12B Problems/Problem 7"
## Problem
Let . What is the ratio of the sum of the odd divisors of to the sum of the even divisors of ?
## Solution
Prime factorize to get . For each odd divisor of , there exist even divisors of , therefore the ratio is
2021 AMC 12B (Problems • Answer Key • Resources) Preceded byProblem 6 Followed byProblem 8 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 All AMC 12 Problems and Solutions | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9170761108398438, "perplexity": 3346.245425172049}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243988953.13/warc/CC-MAIN-20210509002206-20210509032206-00184.warc.gz"} |
https://www.hackmath.net/en/math-problem/16793?tag_id=29 | # Tetrahedral pyramid 8
Let’s all side edges of the tetrahedral pyramid ABCDV be equally long and its base let’s be a rectangle. Determine its volume if you know the deviations A=40° B=70° of the planes of adjacent sidewalls and the plane of the base and the height h=16 of the pyramid.
Result
V = 2368.923
#### Solution:
$A=40 \ ^\circ \ \\ B=70 \ ^\circ \ \\ h=16 \ \\ \ \\ \tan A=\dfrac{ h }{ b/2 } \ \\ \tan B=\dfrac{ h }{ a/2 } \ \\ \ \\ b=2 \cdot \ h / \tan( A)=2 \cdot \ 16 / \tan( 40^\circ ) \doteq 38.1361 \ \\ a=2 \cdot \ h / \tan( B)=2 \cdot \ 16 / \tan( 70^\circ ) \doteq 11.647 \ \\ \ \\ S=a \cdot \ b=11.647 \cdot \ 38.1361 \doteq 444.1731 \ \\ \ \\ V=\dfrac{ 1 }{ 3 } \cdot \ S \cdot \ h=\dfrac{ 1 }{ 3 } \cdot \ 444.1731 \cdot \ 16 \doteq 2368.9234 \doteq 2368.923$
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The annual growth of wood in the forest is estimated at 2%. In how many years will make the forest volume double? | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 1, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6838211417198181, "perplexity": 1322.0484979488801}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-16/segments/1585371618784.58/warc/CC-MAIN-20200406035448-20200406065948-00402.warc.gz"} |
https://brilliant.org/problems/find-the-center/ | # Find The Center
Algebra Level 2
If the numbers $$x−4, 4−x$$ and $$x$$ form an arithmetic progression, what is $$x$$?
× | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6091888546943665, "perplexity": 1022.5273190885803}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-22/segments/1495463608642.30/warc/CC-MAIN-20170526051657-20170526071657-00211.warc.gz"} |
http://blog.math.toronto.edu/GraduateBlog/2011/12/06/2012-13-mackenzie-king-scholarships/ | ## 2012-13 Mackenzie King Scholarships
Student Application Deadline to SGS: Wednesday February 1, 2012
Purpose
There are 2 types of Mackenzie King Scholarships: the “Open” Scholarship and the “Travelling” Scholarship. Both were established to support graduates of Canadian universities who are pursuing graduate studies. Further information about these scholarships can be obtained here: http://www.mkingscholarships.ca/index-e.html
Mackenzie King “Open” Scholarship
Open to graduates of any Canadian university who are pursuing postgraduate (Master’s or Doctoral/PhD) study in any field, in Canada or elsewhere. Its value has been $10,000.00, but could be subject to change. Only 1 “Open” Scholarship is awarded annually at the National competition – applicants interested in applying need be aware of the extremely competitive nature of the award. Mackenzie King “Travelling” Scholarship Open to graduates of any Canadian university who are pursuing postgraduate (Master’s or Doctoral/PhD) study in either the United States or the United Kingdom in the subject area of international relations or industrial relations (these aspects also included within law, history, politics and economics). This scholarship has previously been awarded to 4 individuals annually ($11,000.00 each), but the number and value could be subject to change.
Eligibility
• If a candidate is offered an award, they are not permitted to accept the award in conjunction with any other major award totaling over \$15,000 (NSERC, SSHRC, CIHR, etc.) – however, this amount is subject to change.
• At the time of this application, applicants must either be currently studying in a Canadian university or be a graduate of a Canadian university (and be pursuing graduate studies).
Nomination Process
Departments are not responsible for nominating students for this competition – students must submit their entire application package in hard copy directly to the Graduate Awards Office (Rm 202, 2nd floor, 63 St.George Street) by the deadline. Late applications, or late application materials, will not be accepted.
Application Package for both scholarships:
(if applying to both scholarships, indicate so at the top of the application form)
• Sheets “A” and “B” (each must be typed, clearly state “Sheet A” and “Sheet B” at the top along with the applicant’s name – details regarding these sheets are found on the application form)
• Certified copies of transcripts from all universities attended (ROSI transcripts are not acceptable). Certified photocopies International transcripts may be made at the Graduate Unit and submitted with the application.
• 3 Letters of Reference Total:
Two letters from:
• person under whom the applicant has taken major work at university and is able to give a critical evaluation of the applicant’s plans for graduate study
• senior colleague with whom the applicant has been associated in academic teaching/research and is able to give a critical evaluation of the applicant’s plans for graduate study
And one letter from:
• from a person who can ascribe to the same descriptions above or at least has intimate knowledge of the applicant’s record and ability and is able to give a critical evaluation of the applicant’s plans for graduate study
Each reference letter must clearly state the name and contact information of the referee and must also be signed by the referee; the referee must also seal the letter and sign across the seal
*In order to avoid the loss or misplacement of documents, applicants must assemble the entire application package and submit it themselves in hardcopy to the Graduate Awards Office by the deadline.*
Important Notes
• It is the responsibility of each applicant to ensure that the content within the application form is correctly entered, that all required supporting documentation is provided and adheres to all specified limitations, and that the complete application package is submitted no later than the GAO deadline.
• Applicants will not be notified of any missing documentation after the application has been submitted.
• Documentation that is sent directly to the Board that administers these scholarships will not be considered in this competition.
Results
• All applicants will be notified in March on whether or not their application will be forwarded on to the official competition (UofT is only permitted to nominate 2 individuals for the “Open” Scholarship and 2 individuals for the “Travelling” Scholarship).
• Decisions in this national competition are usually announced by end of May.
Wednesday February 1st, 2012
• The entire application package must be received at the Graduate Awards Office (63 St.George Street, Rm 202, 2nd floor) in hardcopy no later than 4pm on Wednesday February 1st, 2012 (office-hours are 10am-4pm).
Please feel free to contact me with any further questions,
Erin McMahon
Awards Officer, Federal
University of Toronto, School of Graduate Studies
63 St. George Street, Toronto ON, M5S 2Z9
P: 416-978-8260 F: 416-971-2864
erin.mcmahon@sgs.utoronto.ca | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.17724254727363586, "perplexity": 4515.159707481287}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-05/segments/1642320304954.18/warc/CC-MAIN-20220126131707-20220126161707-00444.warc.gz"} |
https://www.gradesaver.com/textbooks/math/algebra/elementary-and-intermediate-algebra-concepts-and-applications-6th-edition/chapter-r-elementary-algebra-review-r-4-polynomials-r-4-exercise-set-page-961/22 | ## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)
$-8a^{6}$
Using the laws of exponents, the given expression, $\left( -2a^2 \right)^{3} ,$ simplifies to \begin{array}{l}\require{cancel} (-2)^3a^{2(3)} \\\\= -8a^{6} .\end{array} | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9894272685050964, "perplexity": 16623.530577964237}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-39/segments/1537267164750.95/warc/CC-MAIN-20180926101408-20180926121808-00518.warc.gz"} |
https://math.stackexchange.com/questions/3106877/calculating-probability-of-sending-a-bit-given-an-error-occurred-in-a-noisy-chan | Calculating probability of sending a bit given an error occurred in a noisy channel
A digital signal “1” or “0” is transmitted through a noisy channel, the received data may be different from the signal sent out. Suppose the transmitter sends out “0” with probability 0.7, and “1” with probability 0.3. When “0” is transmitted, the receiver receives “0” with probability 0.9, and “1” with probability 0.1. When “1” is transmitted, the receiver receives “0” with probability 0.2, and “1” with probability 0.8.
• Find the probability that “1” was transmitted, when error occurs.
My attempt is the following:
We need to calculate P(S=1|error).
P(error) = P(S=0) P(R=1|S=0) + P(S=1) P(R=0|S=1)= (0.7)(0.1)+(0.3)(0.2)=0.13
P(S=1|error)= P(error|S=1) P(S=1) / P(error)
I have all the information except for P(error|S=1) which I am not sure how to calculate.
Any clue?
• Isn't $P(\text{error}|S=1)=.2?$ That's how I interpret the hypothesis that when $1$ is transmitted $0$ is received with probability $.2$ Do I misunderstand? – saulspatz Feb 9 at 23:51
• I think you are right! I missed it – HaneenSu Feb 10 at 0:07
$$P(error|S=1)$$ is just the chance of an error when the digit 1 is sent - it is given in the question as $$0.2$$. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 2, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8275962471961975, "perplexity": 690.7079163784089}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-22/segments/1558232257497.4/warc/CC-MAIN-20190524024253-20190524050253-00035.warc.gz"} |
https://www.aimsciences.org/journal/A0000-0001/2019/2/1 | # American Institute of Mathematical Sciences
eISSN:
2577-8838
All Issues
## Mathematical Foundations of Computing
February 2019 , Volume 2 , Issue 1
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2019, 2(1): 1-9 doi: 10.3934/mfc.2019001 +[Abstract](2794) +[HTML](760) +[PDF](336.95KB)
Abstract:
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Abstract:
Because balanced constraints can overcome the problems of trivial solutions of data classification via minimum cut method, many techniques with different balanced strategies have been proposed to improve data classification accuracy. However, their performances have not been compared comprehensively so far. In this paper, we investigate seven balanced classification methods under the discrete non-local total variational framework and compare their accuracy performances on graph. The two-class classification problem with equality constraints, inequality constraints and Ratio Cut, Normalized Cut, Cheeger Cut models are investigated. For cases of equality constraint, we firstly compare the Penalty Function Method (PFM) and the Augmented Lagrangian Method (ALM), which can transform the constrained problems into unconstrained ones, to show the advantages of ALM. The other cases are all solved using the ALM also. In order to make the comparison fairly, we solve all models using ALM method and using the same proportion of fidelity points and the same neighborhood size on graph. Experimental results demonstrate ALM with the equality balanced constraint has the best classification accuracy compared with other six constraints. 200 words.
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Abstract:
SLAM (simultaneous localization and mapping) system can be implemented based on monocular, RGB-D and stereo cameras. RTAB-MAP is a SLAM system, which can build dense 3D map. In this paper, we present a novel method named SEMANTIC-RTAB-MAP (SRM) to implement a semantic SLAM system based on RTAB-MAP and deep learning. We use YOLOv2 network to detect target objects in 2D images, and then use depth information for precise localization of the targets and finally add semantic information into 3D point clouds. We apply SRM in different scenes, and the results show its higher running speed and accuracy.
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Abstract:
It has been noticed that the performance of multi-ethnic facial expression recognition is affected by other-race effect significantly. Though this phenomenon has been noticed by psychologists and computer vision researchers for decades, the mechanism of other-race effect is still unknown and few work has been done to compensate or remove this effect. This work proposes an ICA-based method to eliminate the other-race effect in automatic 3D facial expression recognition. Firstly, the depth features are extracted from 3D local facial patches, and independent component analysis is applied to project the features into a subspace in which the projected features are mutually independent. The ethnic-related features and expression-related features are supposed to be separated in ICA subspace. Hence, ethnic-sensitive features are then determined by an entropy-based feature selection method and discarded to depress their influence on facial expression recognition. The proposed method is evaluated on benchmark BU-3DFE database, and the experimental results reveal that the influence caused by other-race effect can be suppressed effectively with the proposed method.
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Abstract:
This paper studies a residential PV-ESS energy system scheduling problem with electricity purchase cost, storage degradation cost and surplus PV generated cost [2]. This problem can be viewed as an online optimization problem in time \begin{document}$t \in [1, T]$\end{document} with switching costs between decision at \begin{document}$t-1$\end{document} and \begin{document}$t$\end{document}. We reformulate the problem into a single variable problem with \begin{document}${\bf{s}} = (s_1, ..., s_T)^T$\end{document}, which denotes the storage energy content. We then propose a new algorithm, named Average Receding Horizon Control (ARHC) to solve the PV-ESS energy system scheduling problem. ARHC is an online control algorithm exploiting the prediction information with \begin{document}$W$\end{document}-steps look-ahead. We proved an upper bound on the dynamic regret for ARHC of order \begin{document}$O(nT/W)$\end{document}, where \begin{document}$n$\end{document} is the dimension of decision space. This bound can be converted to a competitive ratio of order \begin{document}$1+O(1/W)$\end{document}. This result overcomes the drawback of the classical algorithm Receding Horizon Control (RHC), which has been proved [11] that it may perform bad even with large look ahead \begin{document}$W$\end{document}. We also provide a lower bound for ARHC of order \begin{document}$O(nT/W^2)$\end{document} on the dynamic regret. ARHC is then used to study a real world case in residential PV-ESS energy system scheduling.
2019, 2(1): 73-81 doi: 10.3934/mfc.2019006 +[Abstract](3460) +[HTML](1103) +[PDF](681.93KB)
Abstract:
In exploratory data mining, most classifiers pay more attention on the accuracy and speed of learned models, but they are lacking of the interpretability. In this paper, an interpretable and comprehensible classifier is proposed based on Linear Discriminant Analysis (LDA) and Axiomatic Fuzzy Sets (AFS). The algorithm utilizes LDA to extract features with the largest inter-class variance. Besides, the proposed approach aims to explore a transformation from the selected feature space to a semantic space where the samples in the same class are made as close as possible to one another, whereas the samples in the different class are as far as possible from one another. Moreover, the descriptions of each class can be obtained by the proposed approach. When compared with well-known classifiers such as LogisticR, C4.5Tree, SVM and KNN, the proposed method not only can achieve better performance in terms of accuracy but also has the capability of interpretability and comprehension. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.694051206111908, "perplexity": 1125.1591512318464}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780056711.62/warc/CC-MAIN-20210919035453-20210919065453-00153.warc.gz"} |
http://www.ck12.org/tebook/CK-12-Chemistry-Intermediate-Teachers-Edition/section/2.0/ | <img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
# Chapter 2: Matter and Change
Difficulty Level: At Grade Created by: CK-12
jcroninone. www.flickr.com/photos/31867606@N04/4038864078. CC BY 2.0.
## Chapter Overview
Chemistry is the study of matter and so it is important to be able to understand the properties of matter and to classify matter based on type. All samples of matter have both physical and chemical properties, and thus can undergo physical and chemical changes. Classifications of matter include elements, compounds, and mixtures. Careful observation of changes in matter must be made in order to determine if each change is physical or chemical in nature.
## Online Resources
See the following Web sites for appropriate activities:
## Pacing the Lessons
Lesson Class Period(s) (60 min)
2.1 Properties of Matter 1
2.2 Classification of Matter 1
2.3 Changes in Matter 1
Chapter Outline
### Chapter Summary
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Date Created:
Jul 25, 2014 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9819080233573914, "perplexity": 4821.604637115853}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-40/segments/1474738660898.27/warc/CC-MAIN-20160924173740-00058-ip-10-143-35-109.ec2.internal.warc.gz"} |