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Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:
Errors in compilations concerning equilibrium and/or data elaboration. Data not recommended. It is strongly suggested to refer to the original papers. | 0 | Theoretical and Fundamental Chemistry |
Endergonic reactions can be pushed by coupling them to another reaction which is strongly exergonic, through a shared intermediate.
This is often how biological reactions proceed. For example, on its own the reaction
may be too endergonic to occur. However it may be possible to make it occur by coupling it to a strongly exergonic reaction – such as, very often, the decomposition of ATP into ADP and inorganic phosphate ions, ATP → ADP + P, so that
This kind of reaction, with the ATP decomposition supplying the free energy needed to make an endergonic reaction occur, is so common in cell biochemistry that ATP is often called the "universal energy currency" of all living organisms. | 0 | Theoretical and Fundamental Chemistry |
In this method the solid particles present into the two immiscible liquids can be easily separated by suspending those solid particles directly into these immiscible or somewhat miscible liquids. | 0 | Theoretical and Fundamental Chemistry |
The process of peak-fitting high energy resolution XPS spectra is a mixture of scientific knowledge and experience. The process is affected by instrument design, instrument components, experimental settings and sample variables. Before starting any peak-fit effort, the analyst performing the peak-fit needs to know if the topmost 15 nm of the sample is expected to be a homogeneous material or is expected to be a mixture of materials. If the top 15 nm is a homogeneous material with only very minor amounts of adventitious carbon and adsorbed gases, then the analyst can use theoretical peak area ratios to enhance the peak-fitting process. Peak fitting results are affected by overall peak widths (at half maximum, FWHM), possible chemical shifts, peak shapes, instrument design factors and experimental settings, as well as sample properties:
* The full width at half maximum (FWHM) values are useful indicators of chemical state changes and physical influences. Their increase may indicate a change in the number of chemical bonds, a change in the sample condition (x-ray damage) or differential charging of the surface (localised differences in the charge state of the surface). However, the FWHM also depends on the detector, and can also increase due to the sample getting charged. When using high energy resolution experiment settings on an XPS equipped with a monochromatic Al K-alpha X-ray source, the FWHM of the major XPS peaks range from 0.3 eV to 1.7 eV. The following is a simple summary of FWHM from major XPS signals: Main metal peaks (e.g. 1s, 2p3, 3d5, 4f7) from pure metals have FWHMs that range from 0.30 eV to 1.0 eV Main metal peaks (e.g. 1s, 2p3, 3d5, 4f7) from binary metal oxides have FWHMs that range from 0.9 eV to 1.7 eV The O (1s) peak from binary metal oxides have FWHMs that, in general, range from 1.0 eV to 1.4 eV The C (1s) peak from adventitious hydrocarbons have FWHMs that, in general, range from 1.0 eV to 1.4 eV
* Chemical shift values depend on the degree of electron bond polarization between nearest-neighbor atoms. A specific chemical shift is the difference in BE values of one specific chemical state versus the BE of one form of the pure element, or of a particular agreed-upon chemical state of that element. Component peaks derived from peak-fitting a raw chemical state spectrum can be assigned to the presence of different chemical states within the sampling volume of the sample.
* Peak shapes depend on instrument parameters, experimental parameters and sample characteristics.
* Instrument design factors include linewidth and purity of X-rays used (monochromatic Al, non-monochromatic Mg, Synchrotron, Ag, Zr), as well as properties of the electron analyzer.
* Settings of the electron analyzer (e.g. pass energy, step size)
* Sample factors that affect the peak fitting are the number of physical defects within the analysis volume (from ion etching, or laser cleaning), and the very physical form of the sample (single crystal, polished, powder, corroded) | 0 | Theoretical and Fundamental Chemistry |
Ring A synthesis (scheme 4) started with reduction of the C9 ketone group in 28 to diol 29 with alane in toluene followed by diol protection in 30 as a dimethyl carbonate. This allowed selective oxidation of the C1 alcohol with DDQ after deprotection to ketone 31. This compound was alkylated to 32 at the C1 ketone group with the Grignard homoallyl magnesium bromide (C4 fragment completing the carbon framework) and deprotected at C11 (TBAF) to diol 33. By reaction with cyclohexylmethylsilyldichloride both alcohol groups participated in a cyclic silyl ether (34) which was again cleaved by reaction with methyl lithium exposing the C11 alcohol in 35. The A ring closure required two ketone groups for a pinacol coupling which were realized by oxidation of the C11 alcohol (TPAP, NMO) to ketone 36 and Wacker oxidation of the allyl group to diketone 37. After formation of the pinacol product 38 the benzyl groups (sodium, ammonia) and the trialkylsilyl groups (TBAF) were removed to form pentaol 39.
The pentaol 39 was protected twice: two bottom hydroxyl groups as a carbonate ester (bis(trichloromethyl)carbonate, pyridine) and the C10 hydroxyl group as the acetate forming 40. The acetonide group was removed (HCl, THF), the C7 hydroxyl group protected as a TES silyl ether and the C11 OH group oxidized (TPAP, NMO) to ketone 41. The ring A diol group was next removed in a combined elimination reaction and Barton deoxygenation with 1,1-thiocarbonyldiimidazole' forming alkene 42. Finally the C15 hydroxyl group was introduced by oxidation at the allyl position with in two steps PPC and sodium acetate (to the enone) and with K-selectride to alcohol 43 which was protected as a TES ether in 44. | 0 | Theoretical and Fundamental Chemistry |
Once the initiation complex is open, the first ribonucleotide is brought into the active site to initiate the polymerization reaction in the absence of a primer. This generates a nascent RNA chain that forms a hetero-duplex with the template DNA strand. However, before entering the elongation phase, polymerase may terminate prematurely and release a short, truncated transcript. This process is called abortive initiation. Many cycles of abortive initiation may occur before the transcript grows to sufficient length to promote polymerase escape from the promoter. Throughout abortive initiation cycles, RNA polymerase remains bound to the promoter and pulls downstream DNA into its catalytic cleft in a scrunching-kind of motion. | 1 | Applied and Interdisciplinary Chemistry |
In stereochemistry, enantiomeric excess (ee) is a measurement of purity used for chiral substances. It reflects the degree to which a sample contains one enantiomer in greater amounts than the other. A racemic mixture has an ee of 0%, while a single completely pure enantiomer has an ee of 100%. A sample with 70% of one enantiomer and 30% of the other has an ee of 40% (70% − 30%). | 0 | Theoretical and Fundamental Chemistry |
Strontium-90 is not quite as likely as caesium-137 to be released as a part of a nuclear reactor accident because it is much less volatile, but is probably the most dangerous component of the radioactive fallout from a nuclear weapon.
A study of hundreds of thousands of deciduous teeth, collected by Dr. Louise Reiss and her colleagues as part of the Baby Tooth Survey, found a large increase in Sr levels through the 1950s and early 1960s. The study's final results showed that children born in St. Louis, Missouri, in 1963 had levels of Sr in their deciduous teeth that was 50 times higher than that found in children born in 1950, before the advent of large-scale atomic testing. Reviewers of the study predicted that the fallout would cause increased incidence of disease in those who absorbed strontium-90 into their bones. However, no follow up studies of the subjects have been performed, so the claim is untested.
An article with the study's initial findings was circulated to U.S. President John F. Kennedy in 1961, and helped convince him to sign the Partial Nuclear Test Ban Treaty with the United Kingdom and Soviet Union, ending the above-ground nuclear weapons testing that placed the greatest amounts of nuclear fallout into the atmosphere.
The Chernobyl disaster released roughly 10 PBq, or about 5% of the core inventory, of strontium-90 into the environment. The Kyshtym disaster released strontium-90 and other radioactive material into the environment. It is estimated to have released 20 MCi (800 PBq) of radioactivity. The Fukushima Daiichi disaster had from the accident until 2013 released 0.1 to 1 PBq of strontium-90 in the form of contaminated cooling water into the Pacific Ocean. | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, the Ledinegg instability occurs in two-phase flow, especially in a boiler tube, when the boiling boundary is within the tube. For a given mass flux J through the tube, the pressure drop per unit length (which typically varies as the square of the mass flux and inversely as the density, i.e., as ) is much less when the flow is wholly of liquid than when the flow is wholly of steam. Thus, as the boiling boundary moves up the tube, the total pressure drop falls, potentially increasing the flow in an unstable manner. Boiler tubes normally overcome this (which is effectively a negative resistance regime) by incorporating a narrow orifice at the entry, to give a stabilising pressure drop on entry. | 1 | Applied and Interdisciplinary Chemistry |
In 1761, Benjamin Franklin wrote a letter describing his experiments on the relationship between color and heat absorption. He found that darker color clothes got hotter when exposed to sunlight than lighter color clothes. One experiment he performed consisted of placing square pieces of cloth of various color out in the snow on a sunny day. He waited some time and then measured that the black pieces sank furthest into the snow of all the colors, indicating that they got the hottest and melted the most snow. | 0 | Theoretical and Fundamental Chemistry |
The noble metals are siderophiles (iron-lovers). They tend to sink into the Earth's core because they dissolve readily in iron either as solid solutions or in the molten state. Most siderophile elements have practically no affinity whatsoever for oxygen: indeed, oxides of gold are thermodynamically unstable with respect to the elements.
Copper, silver, gold, and the six platinum group metals are the only native metals that occur naturally in relatively large amounts. | 1 | Applied and Interdisciplinary Chemistry |
Vflo is suited for distributed hydrologic forecasting in post-analysis and continuous operations. Vflo models may be calibrated by loading precipitation maps for historical events and comparing simulated volume/peak hydrographs to observed hydrographs. Elevation data are taken from a digital elevation model. A vector channel representation is employed. Parameterization utilizes digital data sets at any resolution, including LIDAR terrain data and other digital maps of impervious area, soils, and land use/cover. Vflo is developed to utilize multi-sensor inputs from radar, satellites, rain gauges, or model forecasts. The kinematic wave analogy is used to represent hydraulic conditions in a watershed. | 1 | Applied and Interdisciplinary Chemistry |
The ribosomal protein S1 binds to adenine sequences upstream of the RBS. Increasing the concentration of adenine upstream of the RBS will increase the rate of ribosome recruitment. | 1 | Applied and Interdisciplinary Chemistry |
Factors such as rainfall, wind currents, and the initial explosions at Chernobyl themselves caused the nuclear fallout to spread throughout Europe, Asia, as well as parts of North America. Not only was there a spread of these various radioactive elements previously mentioned, but there were also problems with what are known as hot particles. The Chernobyl reactor didn't just expel aerosol particles, fuel particles, and radioactive gases, but there was an additional expulsion of Uranium fuel fused together with radionuclides. These hot particles could spread for thousands of Kilometers and could produce concentrated substances in the form of raindrops known as Liquid hot particles. These particles were potentially hazardous, even in low-level radiation areas. The radioactive level in each individual hot particle could rise as high as 10 kBq, which is a fairly high dosage of radiation. These liquid hot particle droplets could be absorbed in two main ways; ingestion through food or water, and inhalation. | 0 | Theoretical and Fundamental Chemistry |
Tosyl azide is used for the introduction of azide and diazo functional groups. It is also used as a nitrene source and as a substrate for [3+2] cycloaddition reactions. | 0 | Theoretical and Fundamental Chemistry |
Hexaferrum and epsilon iron (ε-Fe) are synonyms for the hexagonal close-packed (HCP) phase of iron that is stable only at extremely high pressure.
A 1964 study at the University of Rochester mixed 99.8% pure α-iron powder with sodium chloride, and pressed a 0.5-mm diameter pellet between the flat faces of two diamond anvils. The deformation of the NaCl lattice, as measured by x-ray diffraction (XRD), served as a pressure indicator. At a pressure of 13 GPa and room temperature, the body-centered cubic (BCC) ferrite powder transformed to the HCP phase in Figure 1. When the pressure was lowered, ε-Fe transformed back to ferrite (α-Fe) rapidly. A specific volume change of −0.20 cm/mole ± 0.03 was measured. Hexaferrum, much like austenite, is more dense than ferrite at the phase boundary. A shock wave experiment confirmed the diamond anvil results. Epsilon was chosen for the new phase to correspond with the HCP form of cobalt.
The triple point between the alpha, gamma and epsilon phases in the unary phase diagram of iron has been calculated as T = 770 K and P = 11 GPa, although it was determined at a lower temperature of T = 750 K (477 °C) in Figure 1. The Pearson symbol for hexaferrum is hP2 and its space group is P6/mmc.
Another study concerning the ferrite-hexaferrum transformation metallographically determined that it is a martensitic rather than equilibrium transformation.
While hexaferrum is purely academic in metallurgical engineering, it may have significance in geology. The pressure and temperature of Earths iron core are on the order of 150–350 GPa and 3000 ± 1000 °C. An extrapolation of the austenite-hexaferrum phase boundary in Figure 1 suggests hexaferrum could be stable or metastable in Earths core. For this reason, many experimental studies have investigated the properties of HCP iron under extreme pressures and temperatures. Figure 2 shows the compressional behaviour of ε-iron at room temperature up to a pressure as would be encountered halfway through the outer core of the Earth; there are no points at pressures lower than approximately 6 GPa, because this allotrope is not thermodynamically stable at low pressures but will slowly transform into α-iron. | 1 | Applied and Interdisciplinary Chemistry |
The modern optical mapping platform works as follows:
#Genomic DNA is obtained from lysed cells, and randomly sheared to produce a "library" of large genomic molecules for optical mapping.
#A single molecule of DNA is stretched (or elongated) and held in place on a slide under a fluorescent microscope due to charge interactions.
#The DNA molecule is digested by added restriction enzymes, which cleave at specific digestion sites. The resulting molecule fragments remain attached to the surface. The fragment ends at the cleavage sites are drawn back (due to elasticity of linearized DNA), leaving gaps which are identifiable under the microscope.
#DNA fragments stained with intercalating dye are visualized by fluorescence microscopy and are sized by measuring the integrated fluorescence intensity. This produces an optical map of single molecules.
#Individual optical maps are combined to produce a consensus, genomic optical map. | 1 | Applied and Interdisciplinary Chemistry |
The Purine Nucleotide Cycle is a metabolic pathway in protein metabolism requiring the amino acids aspartate and glutamate. The cycle is used to regulate the levels of adenine nucleotides, in which ammonia and fumarate are generated. AMP converts into IMP and the byproduct ammonia. IMP converts to S-AMP (adenylosuccinate), which then converts to AMP and the byproduct fumarate. The fumarate goes on to produce ATP (energy) via oxidative phosphorylation as it enters the Krebs cycle and then the electron transport chain. Lowenstein first described this pathway and outlined its importance in processes including amino acid catabolism and regulation of flux through glycolysis and the Krebs cycle.
AMP is produced after strenuous muscle contraction when the ATP reservoir is low (ADP > ATP) by the adenylate kinase (myokinase) reaction. AMP is also produced from adenine and adenosine directly; however, AMP can be produced through less direct metabolic pathways, such as de novo synthesis of IMP or through salvage pathways of guanine (a purine) and any of the purine nucleotides and nucleosides. IMP is synthesized de novo from glucose through the pentose phosphate pathway which produces ribose 5-P, which then converts to PRPP that with the amino acids glycine, glutamine, and aspartate (see Purine metabolism) can be further converted into IMP. | 1 | Applied and Interdisciplinary Chemistry |
The replication initiator protein (Rep) plays a key role in initiation of replication in plasmids. In its monomer form, Rep binds an iteron and promotes replication. The protein itself is known to contain two independent N-terminal and C-terminal globular domains that subsequently bind to two domains of the iteron. The dimer version of the protein is generally inactive in iteron binding, however it is known to bind to the repE operator. This operator contains half of the iteron sequence making it able to bind the dimer and promote gene expression.
Plasmids containing iterons are all organized very similarly in structure. The gene for Rep proteins is usually found directly downstream of the origin of replication. This means that the iterons themselves are known to regulate the synthesis of the rep proteins. | 1 | Applied and Interdisciplinary Chemistry |
Through its meetings CCPN provides a forum for the discussion of computational and experimental NMR techniques. The aim is to debate and spread best practice in the determination of macromolecular information, including structure, dynamics and biological chemistry. CCPN continues to arrange annual conferences for the UK NMR community (the current being the ninth) and a series of workshops to discuss and promote data standards. Because it is vital to the success of CCPN as a software project and as a coordinated NMR community, its software developers run courses to teach the use of CCPN software and its development framework. They also arrange visits to NMR groups to introduce the CCPN program suite and to gain an understanding of the requirements of users.
CCPN is especially keen to enable young scientists to contribute to and attend its meetings. Accordingly, wherever possible CCPN tries to keep conference fees at a minimum by using contributions that come from our industrial sponsorship and software subscriptions. | 0 | Theoretical and Fundamental Chemistry |
Aside from its immense environmental impacts, Freon 113, like most chlorofluoroalkanes, forms phosgene gas when exposed to a naked flame. | 1 | Applied and Interdisciplinary Chemistry |
The results of each SELDM analysis are written to 5–10 output files, depending on the options that were selected during the analysis-specification process. The five output files that are created for every model run are the output documentation, highway-runoff quality, annual highway runoff, precipitation events, and stormflow file. If the Stream Basin or Stream and Lake Basin output options are selected, then the prestorm streamflow and dilution factor files also are created. If these same two output options are selected and, in addition, one or more downstream water-quality pairs are defined by using the water-quality menu, then the upstream water-quality and downstream water-quality output files also are created by SELDM. If the Stream and Lake Basin Output or Lake Basin Output option is selected, and one or more downstream water-quality pairs are defined by using the water-quality menu, then the Lake Analysis output file is created when the Lake Basin Analysis is run. The output files are written as tab-delimited ASCII text files in a relational database (RDB) format that can be imported into many software packages. This output is designed to facilitate post-modeling analysis and presentation of results.
The benefit of the Monte Carlo analysis is not to decrease uncertainty in the input statistics, but to represent the different combinations of the variables that determine potential risks of water-quality excursions. SELDM provides a method for rapid assessment of information that is otherwise difficult or impossible to obtain because it models the interactions among hydrologic variables (with different probability distributions) that result in a population of values that represent likely long-term outcomes from runoff processes and the potential effects of different mitigation measures. SELDM also provides the means for rapidly doing sensitivity analyses to determine the potential effects of different input assumptions on the risks for water-quality excursions. SELDM produces a population of storm-event and annual values to address the questions about the potential frequency, magnitude, and duration of water-quality excursions. The output represents a collection of random events rather than a time series. Each storm that is generated in SELDM is identified by sequence number and annual-load accounting year. The model generates each storm randomly; there is no serial correlation, and the order of storms does not reflect seasonal patterns. The annual-load accounting years, which are just random collections of events generated with the sum of storm interevent times less than or equal to a year, are used to generate annual highway flows and loads for TMDL analysis and the lake basin analysis.
In 2019, the USGS developed a model post processor for SELDM to facilitate analysis and graphing of results from SELDM simulations; that software, known as InterpretSELDM, is available in the public domain on a USGS ScienceBase site. | 1 | Applied and Interdisciplinary Chemistry |
In a water-cooled power reactor (or in a water-filled spent fuel pool, SFP), if a power surge occurs as a result of a reactivity initiated accident, an understanding of the transfer of heat from the surface of the cladding to the water is very useful. In a French study, metal pipe immersed in water (both under typical PWR and SFP conditions), was electrically heated to simulate the generation of heat within a fuel pin by nuclear processes. The temperature of the pipe was monitored by thermocouples and for the tests conducted under PWR conditions the water entering the larger pipe (14.2 mm diameter) holding the test metal pipe (9.5 mm outside diameter and 600 mm long) was at 280 °C and 15 MPa. The water was flowing past the inner pipe at circa 4 ms and the cladding was subjected to heating at 2200 to 4900 °C s to simulate an RIA. It was found that as the temperature of the cladding increased the rate of heat transfer from the surface of the cladding increased at first as the water boiled at nucleation sites. When the heat flux is greater than the critical heat flux a boiling crisis occurs. This occurs as the temperature of the fuel cladding surface increases so that the surface of the metal was too hot (surface dries out) for nucleation boiling. When the surface dries out the rate of heat transfer decreases, after a further increase in the temperature of the metal surface the boiling resumes but it is now film boiling. | 0 | Theoretical and Fundamental Chemistry |
Research into the use self-healing hydrogels has revealed an effective method for mitigating acid spills through the ability to selectively crosslink under acidic conditions. In a testing done by the University of California San Diego, various surfaces were coated with self healing hydrogels and then mechanically damaged with 300 micrometer wide cracks with the coatings healing the crack within seconds upon exposure of low pH buffers. The hydrogels also can adhere to various plastics due to hydrophobic interactions. Both findings suggest the use of these hydrogels as a sealant for vessels containing corrosive acids. No commercial applications currently exist for implementation of this technology. | 0 | Theoretical and Fundamental Chemistry |
Like plutonium, neptunium has a high affinity for soil. However, it is relatively mobile over the long term, and diffusion of neptunium-237 in groundwater is a major issue in designing a deep geological repository for permanent storage of spent nuclear fuel. Np has a half-life of 2.144 million years and is therefore a long-term problem; but its half-life is still much shorter than those of uranium-238, uranium-235, or uranium-236, and Np therefore has higher specific activity than those nuclides. It is used only to make plutonium-238 when bombarded with neutrons in a lab. | 0 | Theoretical and Fundamental Chemistry |
In 2023, a research team composed of Chuo University, Nihon University, Kanazawa University, and the Research Institute of Innovative Technology for the Earth utilized electronic state informatics to design and synthesize ionic liquids. Subsequently, they conducted precise measurements of carbon dioxide solubility and successfully developed ionic liquids with the highest physical absorption capacity for carbon dioxide to date. | 0 | Theoretical and Fundamental Chemistry |
Sex-Linked Recessive Lethal Test – Males from a strain with yellow bodies are used in this test. The gene for the yellow body lies on the X-chromosome. The fruit flies are fed on a diet of test chemical, and progenies are separated by sex. The surviving males are crossed with the females of the same generation, and if no males with yellow bodies are detected in the second generation, it would indicate a lethal mutation on the X-chromosome has occurred. | 0 | Theoretical and Fundamental Chemistry |
The origin of nitrogenase has been of interest to paleobiologists and is an area of active research. Nitrogenase is thought to have evolved sometime between 1.5-2.2 billion years ago (Ga) although some isotopic support showing nitrogenase evolution as early as around 3.2 Ga. Nitrogenase appears to have evolved from maturase-like proteins, although the function of the preceding protein is currently unknown.
Nitrogenase has three different forms (Nif, Anf, and Vnf) that correspond with the metal found in the active site of the protein (Molybdenum, Iron, and Vanadium respectively). Marine metal abundances over Earth’s geologic timeline are thought to have driven the relative abundance of which form of nitrogenase was most common. Currently, there is no conclusive agreement on which form of nitrogenase arose first. | 1 | Applied and Interdisciplinary Chemistry |
Historically, the mechanisms of carboxypeptidases and endoprotease have been much more well-studied and understood by researchers (Ref #6 Lipscomb 1990). Work within the past two decades has provided vital knowledge regarding the mechanisms of aminopeptidases. The mechanism of
bovine lens LAP and PepA have been elucidated (Ref 1 and 2), however, the exact mechanism of tomato LAP-A is unknown at this time. A search of current literature does not indicate that new research is underway to determine the exact mechanism of LAP-A. Based on the biochemical similarities of the LAPs between kingdoms, the mechanism of LAP-A may be similar to bovine lens LAP and PepA. | 1 | Applied and Interdisciplinary Chemistry |
Strange matter (or strange quark matter) is quark matter containing strange quarks. In extreme environments, strange matter is hypothesized to occur in the core of neutron stars, or, more speculatively, as isolated droplets that may vary in size from femtometers (strangelets) to kilometers, as in the hypothetical strange stars. At high enough density, strange matter is expected to be color superconducting.
Ordinary matter, also referred to as atomic matter, is composed of atoms, with nearly all matter concentrated in the atomic nuclei. Nuclear matter is a liquid composed of neutrons and protons, and they are themselves composed of up and down quarks. Quark matter is a condensed form of matter composed entirely of quarks. When quark matter does not contain strange quarks, it is sometimes referred to as non-strange quark matter. | 0 | Theoretical and Fundamental Chemistry |
One of the innovations for night and all-weather flying used by the US, UK, Japan and Germany during World War II was the use of UV interior lighting to illuminate the instrument panel, giving a safer alternative to the radium-painted instrument faces and pointers, and an intensity that could be varied easily and without visible illumination that would give away an aircraft's position. This went so far as to include the printing of charts that were marked in UV-fluorescent inks, and the provision of UV-visible pencils and slide rules such as the E6B.
They may also be used to test for LSD, which fluoresces under black light while common substitutes such as 25I-NBOMe do not.
Strong sources of long-wave ultraviolet light are used in tanning beds. | 0 | Theoretical and Fundamental Chemistry |
Popular choices for plant biofuels include: oil palm, soybean, castor oil, sunflower oil, safflower oil, corn ethanol, and sugar cane ethanol.
A 2008 Hawaiian oil palm plantation projection stated: "algae could yield from 5,000-10,000 gallons of oil per acre yearly, compared to 250-350 gallons for jatropha and 600-800 gallons for palm oil". That comes to 26 kW per acre or 7 W/m. Typical insolation in Hawaii is around 230 W/m., so converting 3% of the incident solar energy to chemical fuel. Total photosynthetic efficiency would include more than just the biodiesel oil, so this number is a lower bound.
Contrast this with a typical photovoltaic installation, which would produce an average of roughly 22 W/m (roughly 10% of the average insolation), throughout the year. Furthermore, the photovoltaic panels would produce electricity, which is a high-quality form of energy, whereas converting the biodiesel into mechanical energy entails the loss of a large portion of the energy. On the other hand, a liquid fuel is much more convenient for a vehicle than electricity, which has to be stored in heavy, expensive batteries.
Most crop plants store ~0.25% to 0.5% of the sunlight in the product (corn kernels, potato starch, etc.) Ethanol fuel in Brazil has a calculation that results in: "Per hectare per year, the biomass produced corresponds to 0.27 TJ. This is equivalent to 0.86 W/m. Assuming an average insolation of 225 W/m, the photosynthetic efficiency of sugarcane is 0.38%." Sucrose accounts for little more than 30% of the chemical energy stored in the mature plant; 35% is in the leaves and stem tips, which are left in the fields during harvest, and 35% are in the fibrous material (bagasse) left over from pressing. | 0 | Theoretical and Fundamental Chemistry |
Zinc chloride dissolves readily in water to give species and some free chloride. Aqueous solutions of are acidic: a 6 M aqueous solution has a pH of 1. The acidity of aqueous solutions relative to solutions of other Zn salts (say the sulfate) is due to the formation of the tetrahedral chloro aqua complexes where the reduction in coordination number from 6 to 4 further reduces the strength of the O–H bonds in the solvated water molecules.
In alkali solution, zinc chloride converts to various zinc hydroxychlorides. These include , , , and the insoluble . The latter is the mineral simonkolleite. When zinc chloride hydrates are heated, HCl gas evolves and hydroxychlorides result.
When solutions of zinc chloride are treated with ammonia, various ammine complexes are produced. These include and on concentration . The former contains the ion, and the latter is molecular with a distorted tetrahedral geometry. The species in aqueous solution have been investigated and show that is the main species present with also present at lower :Zn ratio. | 0 | Theoretical and Fundamental Chemistry |
During the curing process, single monomers and oligomers, mixed with or without a curing agent, react to form a tridimensional polymeric network.
In the very first part of the reaction branches of molecules with various architectures are formed, and their molecular weight increases in time with the extent of the reaction until the network size is equal to the size of the system. The system has lost its solubility and its viscosity tends to infinite. The remaining molecules start to coexist with the macroscopic network until they react with the network creating other crosslinks. The crosslink density increases until the system reaches the end of the chemical reaction.
Curing can be induced by heat, radiation, electron beams, or chemical additives. To quote from IUPAC: curing "might or might not require mixing with a chemical curing agent". Thus, two broad classes are curing induced by chemical additives (also called curing agents, hardeners) and curing in the absence of additives. An intermediate case involves a mixture of resin and additives that requires external stimulus (light, heat, radiation) to induce curing.
The curing methodology depends on the resin and the application. Particular attention is paid to the shrinkage induced by the curing. Usually small values of shrinkage (2–3%) are desirable. | 0 | Theoretical and Fundamental Chemistry |
The Treatment and management of soils and water in acid sulfate soil landscapes provides an overview of acid sulfate soil management strategies – including a discussion on groundwater management (which is not covered in the Queensland technical manual). | 0 | Theoretical and Fundamental Chemistry |
Reactions are known where the deuterated species reacts faster than the undeuterated analogue, and these cases are said to exhibit inverse kinetic isotope effects (IKIE). IKIE's are often observed in the reductive elimination of alkyl metal hydrides, e.g. (MeNCHCHNMe)PtMe(H). In such cases the C-D bond in the transition state, an agostic species, is highly stabilized relative to the C–H bond.
An inverse effect can also occur in a multistep reaction if the overall rate constant depends on a pre-equilibria prior to the rate-determining step which has an inverse equilibrium isotope effect. For example, the rates of acid-catalyzed reactions are usually 2-3 times greater for reactions in DO catalyzed by DO than for the analogous reactions in HO catalyzed by HO This can be explained for a mechanism of specific hydrogen-ion catalysis of a reactant R by HO (or DO).
:HO + R RH + HO
:RH + HO → HO + P
The rate of formation of products is then d[P]/dt = k[RH] = kK[HO][R] = k[HO][R]. In the first step, HO is usually a stronger acid than RH. Deuteration shifts the equilibrium toward the more strongly bound acid species RD in which the effect of deuteration on zero-point vibrational energy is greater, so that the deuterated equilibrium constant K is greater than K. This equilibrium isotope effect in the first step usually outweighs the kinetic isotope effect in the second step, so that there is an apparent inverse isotope effect and the observed overall rate constant k = kK decreases. | 0 | Theoretical and Fundamental Chemistry |
For mutually insoluble compounds, Dalton's law states that the partial pressure of a non aqueous phase liquid (NAPL) is equal to its vapor pressure, and that the NAPL in contact with water will boil when the vapor pressure of water plus the vapor pressure of the VOC is equal to ambient pressure. When a VOC-steam bubble is formed the composition of the bubble is proportional to the composite’s respective vapor pressures. | 1 | Applied and Interdisciplinary Chemistry |
In alchemy, albedo, or leucosis, is the second of the four major stages of the Magnum Opus, along with nigredo, citrinitas and rubedo. It is a Latinicized term meaning "whiteness". Following the chaos or massa confusa of the nigredo stage, the alchemist undertakes a purification in albedo, which is literally referred to as ablutio – the washing away of impurities. This phase is concerned with "bringing light and clarity to the prima materia (the First Matter)".
In this process, the subject is divided into two opposing principles to be later coagulated to form a unity of opposites or coincidentia oppositorum during rubedo. Alchemists also applied it to an individual's soul after the first phase is completed, which entailed the decay of matter. In Medieval literature, which developed an intricate system of images and symbols for alchemy, the dove often represented this stage, while the raven symbolized nigredo.
Titus Burckhardt interprets the albedo as the end of the lesser work, corresponding to a spiritualization of the body. Claiming the goal of this portion of the process is to regain the original purity and receptivity of the soul. | 1 | Applied and Interdisciplinary Chemistry |
The molar conductivity of an electrolyte solution is defined as its conductivity divided by its molar concentration.
where:
: κ is the measured conductivity (formerly known as specific conductance),
: c is the molar concentration of the electrolyte.
The SI unit of molar conductivity is siemens metres squared per mole (S m mol). However, values are often quoted in S cm mol. In these last units, the value of Λ may be understood as the conductance of a volume of solution between parallel plate electrodes one centimeter apart and of sufficient area so that the solution contains exactly one mole of electrolyte. | 0 | Theoretical and Fundamental Chemistry |
Some harmful algal blooms resulting from eutrophication, are toxic to plants and animals. Freshwater algal blooms can pose a threat to livestock. When the algae die or are eaten, neuro- and hepatotoxins are released which can kill animals and may pose a threat to humans. An example of algal toxins working their way into humans is the case of shellfish poisoning. Biotoxins created during algal blooms are taken up by shellfish (mussels, oysters), leading to these human foods acquiring the toxicity and poisoning humans. Examples include paralytic, neurotoxic, and diarrhoetic shellfish poisoning. Other marine animals can be vectors for such toxins, as in the case of ciguatera, where it is typically a predator fish that accumulates the toxin and then poisons humans. | 1 | Applied and Interdisciplinary Chemistry |
Prof. dr. O.P. Kuipers published 365 articles in scientific papers, 2 books and 18 chapters in books. 34 publications appeared in 2015. Kuipers articles have been cited over 26 148 times and he has a H-index of 84 and an i10 index of 278. This means that 80 of his articles have been cited at least 80 times and that 278 articles have been cited more than 10 times.
* [http://www.rug.nl/staff/o.p.kuipers/research/publications.html An overview of the most significant publications of Oscar Kuipers.] | 0 | Theoretical and Fundamental Chemistry |
The Indian Rivers Inter-link project is similar in scope and technical challenges as other major global river inter-link projects, such as:
#Rhine–Main–Danube Canal – completed in 1992, and also called the Europa Canal, it inter-links the Main river to the Danube river, thus connecting North Sea and Atlantic Ocean to the Black Sea. It provides a navigable artery between the Rhine delta at Rotterdam in the Netherlands to the Danube Delta in eastern Romania. It is 171 km long, has the summit altitude (between the Hilpoltstein and Bachhausen locks) is 406 m above sea level, the highest point on Earth reachable by ships from the sea. In 2010, the inter-link provided navigation for 5.2 million tonnes of goods, mostly food, agriculture, ores and fertilizers, reducing the need for 250,000 truck trips per year. The canal is also a source for irrigation, industrial water and power generation plants.
#Illinois Waterway system consists of 541 kilometres of interlink that connects a system of rivers, lakes, and canals to provide a shipping connection from the Great Lakes to the Gulf of Mexico via the Mississippi River. It provides a navigation route; primary cargoes are coal to powerplants, chemicals and petroleum upstream, and agriculture produce downstream primarily for export. The Illinois waterway is the principal source of industrial and municipal services water needs along its way; it serves the petroleum refining, pulp and paper processing, metal works, fermentation and distillation, and agricultural products industries.
#Tennessee–Tombigbee Waterway is a 377 kilometre man-made waterway that interlinks the Tennessee River to the Black Warrior-Tombigbee River in the United States. The Tennessee–Tombigbee Waterway links major coal producing regions to coal consuming regions, and serves as commercial navigation for coal and timber products. Industries that utilize these natural resources have found the Waterway to be their most cost-efficient mode of transportation. The water from the Tenn-Tom Waterway is a major source of industrial water supply, public drinking water supply, and irrigation along its way.
#Gulf Intracoastal Waterway, completed in 1949, interlinks 8 rivers, and is located along the Gulf Coast of the United States. It is a navigable inland waterway running approximately 1700 kilometres from Florida to Texas. It is the third busiest waterway in the United States, handling 70 million tonnes of cargo per year, and a major low cost, ecologically friendly and low carbon footprint way to import, export and transport raw materials and products for industrial, chemical and petrochemical industries in the United States. It has also become a significant source for fishing industry as well as for harvesting and shipping shellfish along the coast line of the United States.
#The Central Yunnan Water Diversion Project is a water diversion project from the Jinsha River with 63 tunnels of total length 600 km to the Dianchi Lake in Yunnan province of China. Once this project is completed, it would be world's longest tunnel relegating Delaware Aqueduct tunnel of 137 km to second place.
#Murray–Darling basin, this region in southern Australia with two rivers and associated watercourses was engineered for agriculture and a number of flows were altered over decades with the earliest alterations beginning in 1890. Among the results were changes in seasonal flows causing numerous ecological problems including cyanobacteria blooms killing off fishes, high salinity, acidification, and decline in numerous species of plants and animals. A study of attempts to repair the ecology that began in 2012 were reported as failing in 2017.
Other completed rivers inter-linking projects include the Marne-Rhine Canal in France, the All-American Canal and California State Water Project in the United States, South–North Water Transfer Project in China, etc. | 1 | Applied and Interdisciplinary Chemistry |
Bacterial recombination undergoes various different processes. The processes include: transformation, transduction, conjugation and homologous recombination. Homologous recombination relies on cDNA transferring genetic material. Complementary DNA sequences transport genetic material in the identical homologous chromosomes. The paternal and maternal paired chromosomes will align in order for the DNA sequences to undergo the process of crossing over. Transformation involves the uptake of exogenous DNA from the encircling environment. DNA fragments from a degraded bacterium will transfer into the surrounding, competent bacterium resulting in an exchange of DNA from the recipient. Transduction is associated with viral-mediated vectors transferring DNA material from one bacterium to another within the genome. Bacterial DNA is placed into the bacteriophage genome via bacterial transduction. In bacterial conjugation, DNA is transferred via cell-to-cell communication. Cell-to-cell communication may involve plasmids that allow for the transfer of DNA into another neighboring cell. The neighboring cells absorb the F-plasmid (fertility plasmid: inherited material that is present in the chromosome). The recipient and donor cell come into contact during a F-plasmid transfer. The cells undergo horizontal gene transfer in which the genetic material is transferred.
Mechanisms for double-stranded breaks
The RecBCD pathway in homologous recombination repairs the double-strand breaks in DNA that has degraded in bacteria. Base pairs attached to the DNA strands go through an exchange at a Holliday junction. In the second step of bacterial recombination, branch migration. involves the base pairs of the homologous DNA strands to continuously be interchanged at a Holliday junction. This results in the formation of two DNA duplexes. The RecBCD pathway undergoes helicase activity by unzipping the DNA duplex and stops when the nucleotide sequence reaches 5′-GCTGGTGG-3′. This nucleotide sequence is known as the Chi site. RecBCD enzymes will change after the nucleotide sequence reaches the Chi site. The RecF pathway repairs the degradation of the DNA strands. | 1 | Applied and Interdisciplinary Chemistry |
Uridine diphosphate, abbreviated UDP, is a nucleotide diphosphate. It is an ester of pyrophosphoric acid with the nucleoside uridine. UDP consists of the pyrophosphate group, the pentose sugar ribose, and the nucleobase uracil.
UDP is an important factor in glycogenesis. Before glucose can be stored as glycogen in the liver and muscles, the enzyme UDP-glucose pyrophosphorylase forms a UDP-glucose unit by combining glucose 1-phosphate with uridine triphosphate, cleaving a pyrophosphate ion in the process. Then, the enzyme glycogen synthase combines UDP-glucose units to form a glycogen chain. The UDP molecule is cleaved from the glucose ring during this process and can be reused by UDP-glucose pyrophosphorylase. | 1 | Applied and Interdisciplinary Chemistry |
Ada Hitchins was born on 26 June 1891 in Tavistock, Devon, England, the daughter of William Hedley Hitchins, a supervisor of customs and excise, and his wife Annie Sarah Pearsons. The family lived for a time in Campbeltown, Scotland, where Hitchins attended high school, graduating in 1909. From there, she went to the University of Glasgow, obtaining her bachelor's degree in science, with honors, in 1913. She was awarded prizes in botany and geology, as well as being accorded special distinction for her work in chemistry. | 0 | Theoretical and Fundamental Chemistry |
In molecular biology, TBST (or TTBS) is a mixture of tris-buffered saline (TBS) (a buffer solution) and Polysorbate 20 (a polysorbate-type nonionic surfactant). Polysorbate 20 is also known as Tween 20, a commercial brand name. It is a common detergent used in many buffers for washing nitrocellulose membrane in western blotting and microtiter plate wells in ELISA assays. Tris is a buffer that maintains a pH of 7–9.2. | 1 | Applied and Interdisciplinary Chemistry |
The I. I. Rabi Award, founded in 1983, is awarded annually by IEEE.
: "The Rabi Award is to recognize outstanding contributions related to the fields of atomic and molecular frequency standards, and time transfer and dissemination."
The award is named after Isidor Isaac Rabi, Nobel Prize winner in 1944. He was the first recipient of the award, for his experimental and theoretical work on atomic beam resonance spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
V. G. Khlopin began to study the distribution of helium in freely emitting gases of the country in 1922-1923. In 1924, he and A. I. Lakashuk discovered helium in the gases of the Novouzensky district of Saratov province; and in the period from 1924 to 1936, V. G. Khlopin and his students (E. K. Gerling, G. M. Ermolina, B. A. Nikitin, I. E. Starik, P. I. Tolmachev, and others) analyzed many samples of natural gases and created a distribution map based on the data. For the first time a new type of gas jets in the Kokand area, called "air jets" and characteristic of wide mountain basins (1936), was identified. | 0 | Theoretical and Fundamental Chemistry |
Bronzing is a process by which a bronze-like surface is applied to other materials (metallic or non-metallic). Some bronzing processes are merely simulated finishes (patinas) applied to existing metal surfaces, or coatings of powdered metal that give the appearance of a solid metal surface. In other cases, an actual layer of heavy copper is electroplated onto an object to produce a bronze-like surface. This electroplating is the method traditionally used for "bronzing" of baby shoes, but to electroplate a non-conductive item like a baby shoe, a conductive material must first be applied, then the copper plating is done. | 0 | Theoretical and Fundamental Chemistry |
* EC requires simple equipment and is easy to operate with sufficient operational latitude to handle most problems encountered on running.
* Wastewater treated by EC gives palatable, clear, colorless and odorless water.
* Sludge formed by EC tends to be readily settable and easy to de-water, compared to conventional alum or ferric hydroxide sludges, because the mainly metallic oxides/hydroxides have no residual charge.
* Flocs formed by EC are similar to chemical floc, except that EC floc tends to be much larger, contains less bound water, is acid-resistant and more stable, and therefore, can be separated faster by filtration.
* EC can produce effluent with less TDS content as compared with chemical treatments, particularly if the metal ions can be precipitated as either hydroxides or carbonates (such as magnesium and calcium). EC generally has little if any impact on sodium and potassium ions in solution.
* The EC process has the advantage of removing the smallest colloidal particles, because the applied electric field neutralises any residual charge, thereby facilitating the coagulation.
* The EC process generally avoids excessive use of chemicals and so there is reduced requirement to neutralize excess chemicals and less possibility of secondary pollution caused by chemical substances added at high concentration as when chemical coagulation of wastewater is used.
* The gas bubbles produced during electrolysis can conveniently carry the pollutant components to the top of the solution where it can be more easily concentrated, collected and removed by a motorised skimmer.
* The electrolytic processes in the EC cell are controlled electrically and with no moving parts, thus requiring less maintenance.
* Dosing incoming waste water with sodium hypochlorite assists reduction of biochemical oxygen demand (BOD) and consequent chemical oxygen demand (COD) although this should be avoided for wastewater containing high levels of organic compounds or dissolved ammonia (NH4+) due to formation of trihalogenated methanes (THMs) or other chlorinated organics. Sodium hypochlorite can be generated electrolytically in an E cell using platinum and similar inert electrodes or by using external electrochlorinators.
* Due to the excellent EC removal of suspended solids and the simplicity of the EC operation, tests conducted for the U.S. Office of Naval Research concluded that the most promising application of EC in a membrane system was found to be as pretreatment to a multi-membrane system of UF/RO or microfiltration/reverse osmosis (MF/RO). In this function the EC provides protection of the low-pressure membrane that is more general than that provided by chemical coagulation and more effective. EC is very effective at removing a number of membrane fouling species (such as silica, alkaline earth metal hydroxides and transition group metals) as well as removing many species that chemical coagulation alone cannot remove. (see Refractory Organics) | 1 | Applied and Interdisciplinary Chemistry |
Earths atmosphere and hydrosphere—Earths heat engine—are coupled processes that constantly even out solar heating imbalances through evaporation of surface water, convection, rainfall, winds and ocean circulation, when distributing heat around the globe.
A Hadley cell is an example of a heat engine. It involves the rising of warm and moist air in the earth's equatorial region and the descent of colder air in the subtropics creating a thermally driven direct circulation, with consequent net production of kinetic energy. | 0 | Theoretical and Fundamental Chemistry |
The origin of the name Ariconium is uncertain, as is its pre-Roman name. The Romans often named a place in recognition of some feature of the terrain, or in recognition of the people then living in the area. There is a similarity to other Roman place-names such as Viroconium (post-Roman Welsh: Caer Guricon), also known as Uriconium, but as yet no established connection to them.
It is generally believed that Ariconium is the origin of the name of the post-Roman kingdom of Ergyng, although Ariconium was located outside the later boundaries of Ergyng. It is plausible that both derive from an earlier name for a wider area. In turn, Ergyng is believed to have given its name to Archenfield.
Since 2008, it has been used as the name of a united benefice of six Church of England parishes in the area - Aston Ingham, Hope Mansell, Lea, Linton, Upton Bishop and Weston under Penyard. | 1 | Applied and Interdisciplinary Chemistry |
The midbody is a transient structure found in mammalian cells and is present near the end of cytokinesis just prior to the complete separation of the dividing cells. The structure was first described by Walther Flemming in 1891. | 1 | Applied and Interdisciplinary Chemistry |
In fluid dynamics, Rayleigh problem also known as Stokes first problem is a problem of determining the flow created by a sudden movement of an infinitely long plate from rest, named after Lord Rayleigh and Sir George Stokes. This is considered as one of the simplest unsteady problem that have exact solution for the Navier-Stokes equations. The impulse movement of semi-infinite plate was studied by Keith Stewartson. | 1 | Applied and Interdisciplinary Chemistry |
Butterfly wings are a new site of porphyrin synthesis and cleavage where bilin is portrayed; the expression of the lipocalin bilin-binding protein in Pieris brassicae. The function of the biliprotein during wing development is still unknown, as is the existence of an active pathway for porphyrin synthesis and cleavage in insect wings, which has been demonstrated here for the first time. The bilin-binding protein from Pieris brassicae, which was discovered to have a crystal structure, was one of the initial members of the lipocalins protein superfamily, which has since grown significantly. It is a blue pigment protein that can be clearly identified by its amino acid sequence and crystal structure. The bilin-binding protein is predominantly present in hemolymph, fat body, and epidermis in the last instar larval and in the wings of the adult insect of Pieris brassicae. Although it has recently been discovered that three swallowtail butterfly larval color patterns are correlated with the combination of bilin-binding protein and the yellow-related gene, additional physiological activities are still unknown. Normally, insect bilins are joined to proteins to create a variety of biliproteins that have been identified in Lepidoptera and other insects. The presence of the blue and yellow pigments contributes to the blue-green hue of some lepidopteran larvae. Blue pigments and yellow carotenoids are thought to work together as camouflage.
Bilin-binding protein is a member of the lipocalin family, which includes extracellular proteins with a number of molecular ligand features in common, including the ability to bind tiny, primarily lipophilic compounds like retinol. Members of the lipocalin family have mostly been classified as transport proteins, but it is clear that they also perform a range of other tasks, including retinol transport, invertebrate cryptic coloring, olfaction, and pheromone transmission. There is a lot of structural and functional variation in the lipocalin family, both within and between species. | 1 | Applied and Interdisciplinary Chemistry |
In the early 1950s, Frohring received patents for Frohring Cement Mixers, a line of compact, portable mixers than can be moved out to a field and operated by hand, electric motor, gasoline motor or tractor motor. In 1953, Frohring patented a neurological research device known as a biothesiometer, used to determine a patient's sensitivity to vibration. Other patents include a formula for hypo-alergic milk, a process of making liquid malted milk, and a method for determining vitamin A deficiency, and a method for extracting carotene.
He was made an honorary doctor of science by McKinley-Roosevelt College in Chicago, Illinois. | 0 | Theoretical and Fundamental Chemistry |
It can be prepared by reacting carbon tetrachloride with hydrogen fluoride in the presence of a catalytic amount of antimony pentachloride:
:CCl + 2HF CClF + 2HCl
This reaction can also produce trichlorofluoromethane (CClF), chlorotrifluoromethane (CClF) and tetrafluoromethane (CF). | 1 | Applied and Interdisciplinary Chemistry |
Plumbosolvency is the ability of a solvent, notably water, to dissolve lead. In the public supply of water this is an undesirable property. In (usually older) consumers' premises plumbosolvent water can attack lead pipes, lead service lines, and any lead in solder used to join copper.
Plumbosolvency of water can be countered by achieving a pH of 7.5 by increasing the pH with lime or sodium hydroxide (lye), or by providing a protective coating to the inside of lead pipes by the addition of phosphate at the water treatment works.
While optimal pH for prevention of plumbosolvency is 7.5, performance remains very good in the range pH 7.2-7.6.
Achieving this pH has been shown to decrease population blood lead concentrations.(3, 4)
Chlorinating water also reduces dissolved lead. It causes the interiors of lead pipes to become coated with lead chloride, which is very insoluble in cold water. However, lead chloride is fairly soluble in hot water. For this reason, water that is to be used for drinking or the preparation of food should never be taken from a hot-water tap, if the water may have been in contact with lead. Water should be taken from a cold-water tap, and heated in a pan or kettle that does not contain lead or lead solder. | 0 | Theoretical and Fundamental Chemistry |
Turbulence is flow characterized by recirculation, eddies, and apparent randomness. Flow in which turbulence is not exhibited is called laminar. The presence of eddies or recirculation alone does not necessarily indicate turbulent flow—these phenomena may be present in laminar flow as well. Mathematically, turbulent flow is often represented via a Reynolds decomposition, in which the flow is broken down into the sum of an average component and a perturbation component.
It is believed that turbulent flows can be described well through the use of the Navier–Stokes equations. Direct numerical simulation (DNS), based on the Navier–Stokes equations, makes it possible to simulate turbulent flows at moderate Reynolds numbers. Restrictions depend on the power of the computer used and the efficiency of the solution algorithm. The results of DNS have been found to agree well with experimental data for some flows.
Most flows of interest have Reynolds numbers much too high for DNS to be a viable option, given the state of computational power for the next few decades. Any flight vehicle large enough to carry a human ( > 3 m), moving faster than is well beyond the limit of DNS simulation ( = 4 million). Transport aircraft wings (such as on an Airbus A300 or Boeing 747) have Reynolds numbers of 40 million (based on the wing chord dimension). Solving these real-life flow problems requires turbulence models for the foreseeable future. Reynolds-averaged Navier–Stokes equations (RANS) combined with turbulence modelling provides a model of the effects of the turbulent flow. Such a modelling mainly provides the additional momentum transfer by the Reynolds stresses, although the turbulence also enhances the heat and mass transfer. Another promising methodology is large eddy simulation (LES), especially in the form of detached eddy simulation (DES) — a combination of LES and RANS turbulence modelling. | 1 | Applied and Interdisciplinary Chemistry |
For its main use as a fertilizer urea is mostly marketed in solid form, either as prills or granules. Prills are solidified droplets, whose production predates satisfactory urea granulation processes. Prills can be produced more cheaply than granules, but the limited size of prills (up to about 2.1 mm in diameter), their low crushing strength, and the caking or crushing of prills during bulk storage and handling make them inferior to granules. Granules are produced by acretion onto urea seed particles by spraying liquid urea in a succession of layers. Formaldehyde is added during the production of both prills and granules in order to increase crushing strength and suppress caking. Other shaping techniques such as pastillization (depositing uniform-sized liquid droplets onto a cooling conveyor belt) are also used. | 0 | Theoretical and Fundamental Chemistry |
The Derjaguin approximation (or sometimes also referred to as the proximity approximation), named after the Russian scientist Boris Derjaguin, expresses the force profile acting between finite size bodies in terms of the force profile between two planar semi-infinite walls. This approximation is widely used to estimate forces between colloidal particles, as forces between two planar bodies are often much easier to calculate. The Derjaguin approximation expresses the force F(h) between two bodies as a function of the surface separation as
where W(h) is the interaction energy per unit area between the two planar walls and R the effective radius. When the two bodies are two spheres of radii R and R, respectively, the effective radius is given by
Experimental force profiles between macroscopic bodies as measured with the surface forces apparatus (SFA) or colloidal probe technique are often reported as the ratio F(h)/R. | 0 | Theoretical and Fundamental Chemistry |
The part to be coated is immersed in a bath of electrolyte which usually consists of a dilute alkaline solution such as KOH. It is electrically connected, so as to become one of the electrodes in the electrochemical cell, with the other "counter-electrode" typically being made from an inert material such as stainless steel, and often consisting of the wall of the bath itself.
Potentials of over 200 V are applied between these two electrodes. These may be continuous or pulsed direct current (DC) (in which case the part is simply an anode in DC operation), or alternating pulses (alternating current or "pulsed bi-polar" operation) where the stainless steel counter electrode might just be earthed. | 1 | Applied and Interdisciplinary Chemistry |
and other lanthanide phthalocyanines are of interest in the development of organic thin-film field-effect transistors.
derivatives can be selected to change color in the presence of certain molecules, such as in gas detectors; for example, the thioether derivative changes from green to brownish-purple in the presence of NADH. | 0 | Theoretical and Fundamental Chemistry |
Normally the y-axis is pressure ratio (P/P), where P is stagnation (or total head) pressure.
ΔT/T (or similar), where T is stagnation (or total head) temperature, is also used. | 0 | Theoretical and Fundamental Chemistry |
In SI units, number density is measured in m, although cm is often used. However, these units are not quite practical when dealing with atoms or molecules of gases, liquids or solids at room temperature and atmospheric pressure, because the resulting numbers are extremely large (on the order of 10). Using the number density of an ideal gas at and as a yardstick: is often introduced as a unit of number density, for any substances at any conditions (not necessarily limited to an ideal gas at and ). | 0 | Theoretical and Fundamental Chemistry |
*Padma Bhushan (1964)
*Commander of the Order of the British Empire (CBE) (1943 Birthday Honours)
*Fellow of Indian Academy of Science, Bangalore, Indian Chemical Association and Royal Society of Chemistry (London)
*Founder Secretary, Indian Chemical Society, President (1935–36), Indian Society of Soil Science
*Member, Council (1935–38) and as Vice-President (1941–42)
*Foreign Secretary, INSA (1943–44) and (1947–51)
*General President, Indian Science Congress Association (1952). | 0 | Theoretical and Fundamental Chemistry |
Haworth projections are a related chemical notation used to represent sugars in ring form. The groups on the right hand side of a Fischer projection are equivalent to those below the plane of the ring in Haworth projections. Fischer projections should not be confused with Lewis structures, which do not contain any information about three dimensional geometry. Newman projections are another system that can be used as they showcase the structure of a molecule in the staggered or eclipsed conformation states. The wedge and dash notation will help to showcase the stereochemistry within a specific molecule. | 0 | Theoretical and Fundamental Chemistry |
UV/Vis spectroscopy is widely used as a technique in chemistry to analyze chemical structure, the most notable one being conjugated systems. UV radiation is often used to excite a given sample where the fluorescent emission is measured with a spectrofluorometer. In biological research, UV radiation is used for quantification of nucleic acids or proteins. In environmental chemistry, UV radiation could also be used to detect Contaminants of emerging concern in water samples.
In pollution control applications, ultraviolet analyzers are used to detect emissions of nitrogen oxides, sulfur compounds, mercury, and ammonia, for example in the flue gas of fossil-fired power plants. Ultraviolet radiation can detect thin sheens of spilled oil on water, either by the high reflectivity of oil films at UV wavelengths, fluorescence of compounds in oil, or by absorbing of UV created by Raman scattering in water. UV absorbance can also be uesd to quantify contaminants in wastewater. Most commonly used 254 nm UV absorbance is genrally used as a surrogate parameters to quantify NOM. Another form of light-based detection method uses a wide spectrum of excitation emission matrix (EEM) to detect and identify contaminants based on their flourense properties. EEM could be used to discriminate different groups of NOM based on the difference in light emission and excitation of fluorophores. NOMs with certain molecular structures are reported to have fluorescent properties in a wide range of excitation/emission wavelengths.
Ultraviolet lamps are also used as part of the analysis of some minerals and gems. | 0 | Theoretical and Fundamental Chemistry |
The efficacy of the Diphoterine solution has been shown to be effective in a two-year study on humans and also in a study on animals. Its effectiveness as compared to use of water alone, and therefore its necessity, has been questioned by some medical experts. On the other hand these statements do not provide any studies that compare the effectiveness of the Diphoterine solution compare to water.
The largest case series reported to date does compare the effectiveness of water and the Diphoterine solution. "One hundred eighty cases of alkali splashes to the skin were evaluated clinically. Two groups were compared; those who had applied Diphoterine first and those who had applied water first." Here are the results of this independent study: "There were no signs of chemical burn in 52.9% of the group who applied Diphoterine first compared with 21.4% of the group who applied water first. Only 7.9% of the group who applied Diphoterine first had blisters or more severe signs compared with 23.8% of the group who applied water first. The differences were statistically significant (P < 0.001). After implementation of Diphoterine the "first aid" injury rate for chemical burns fell 24.7% (95% CI 0.5–43.0%)." | 0 | Theoretical and Fundamental Chemistry |
It has also been seen that metabolic phenotype of tumor cells changes to adapt to the prevailing local conditions. A convergence between phenotypic and metabolic state transitions that confers a survival advantage to cancer cells against clinically used drug combinations like taxanes and anthracyclines have also been reported while drug resistant cancer cells had increased activity of both the glycolytic and oxidative pathways and glucose flux through the pentose phosphate pathway (PPP). Some of the fatty acids have been linked to acquire resistance against some of the cancer drugs. Fatty acid synthase (FASN), a key complex catalyzing fatty acid synthesis has been found to be linked to acquired docetaxel, trastuzumab and adriamycin resistance in breast cancer. Similar resistance have been found with intrinsic gemcitabine and radiation resistance in pancreatic cancer. Glutaminolysis is linked to cisplatin resistance via the activation of mTORC1 signaling in gastric cancer. | 1 | Applied and Interdisciplinary Chemistry |
The potential difference (η) between the electrically conductive electrode (V) and the electrolyte (V) causes a potential gradient which is distributed latterly across the BPE-electrolyte interface, with one extreme having the highest potential (anode +η) and the other extreme having the lowest potential (cathode -η). Comparing to the electrolyte potential (V) gradient/drop; the electrode potential (V) does not change between the BPE poles, this is due to the high conductivity of the electrodes which is higher than 10 S/m for most of steel alloys, compared to the solution conductivity in the range of 5.5 μS/m for ionized water and 5 S/m for seawater. | 0 | Theoretical and Fundamental Chemistry |
Dexmethylphenidate has a 4–6 hour duration of effect. A long-acting formulation, Focalin XR, which spans 12 hours is also available and has been shown to be as effective as -TMP (threo-methylphenidate) XR (extended release) (Concerta, Ritalin LA), with flexible dosing and good tolerability. It has also been demonstrated to reduce ADHD symptoms in both children and adults. d-MPH has a similar side-effect profile to MPH and can be administered without regard to food intake. | 0 | Theoretical and Fundamental Chemistry |
Tropoelastin is a protein, of size 72kDa, that comes together via cross-links to form elastin in the extracellular matrix of the cell. The cross-link formation process is mediated by lysyl oxidase. One of the major reasons that elastin can withstand high levels of stress in the body without experiencing any physical deformation is that the underlying tropoelastin contains domains that are highly hydrophobic. These hydrophobic domains, consisting overwhelmingly of alanine, proline, glycine, and valine, tend towards instability and disorderliness, ensuring that the elastin does not lock into any specific confirmation. Thus, ELPs consisting of the Val-Pro-Gly-X-Gly monomeric units, which bear resemblance to the repetitive tropoelastin hydrophobic domains, are highly disordered below their T Even above their T in their aggregated state, ELPs are only partially ordered. This is due to the fact that the proline and glycine amino acids are present in high amounts in the ELP. Glycine, due to the lack of a bulky side chain, enables the biopolymer to be flexible and proline prevents the formation of stable hydrogen bonds in the ELP backbone. It is important to note, however, that certain segments of the ELP may be able to form instantaneous type II β turns, but these turns are not long-lasting and do not resemble true β sheets, when the NMR chemical shifts are compared. | 0 | Theoretical and Fundamental Chemistry |
Sulfide compounds can be prepared in several different ways:
#Direct combination of elements:
#:Example: Fe + S → FeS
#Reduction of a sulfate:
#:Example: MgSO + 4C → MgS + 4CO
#Precipitation of an insoluble sulfide:
#:Example: M + HS → MS + 2H | 0 | Theoretical and Fundamental Chemistry |
Aratashen (, also Romanized as Arratashen; also, Artashen; until 1978 Zeyva Hayi – meaning "Armenian Zeyva", Zeyva, Bol’shaya Zeyva and Nerkin-Zeyva) is a town in the Armavir Province of Armenia. It is located on the Ararat Plain. | 1 | Applied and Interdisciplinary Chemistry |
Early experiments measured the force between mica surfaces in air or vacuum. The technique has been extended, however, to enable an arbitrary vapor or solvent to be introduced between the two surfaces. In this way, interactions in various media can be carefully probed, and the dielectric constant of the gap between the surfaces can be tuned. Moreover, use of water as a solvent enables the measurement of interactions between biological molecules (such as lipids in biological membranes or proteins) in their native environment. In a solvent environment, SFA can even measure the oscillatory solvation and structural forces arising from the packing of individual layers of solvent molecules. It can also measure the electrostatic double layer forces between charged surfaces in an aqueous medium with electrolyte. | 0 | Theoretical and Fundamental Chemistry |
Sedimentation potential occurs when dispersed particles move under the influence of either gravity or centrifugation or electricity in a medium. This motion disrupts the equilibrium symmetry of the particles double layer. While the particle moves, the ions in the electric double layer lag behind due to the liquid flow. This causes a slight displacement between the surface charge and the electric charge of the diffuse layer. As a result, the moving particle creates a dipole moment. The sum of all of the dipoles generates an electric field which is called sedimentation potential'. It can be measured with an open electrical circuit, which is also called sedimentation current.
There are detailed descriptions of this effect in many books on colloid and interface science. | 0 | Theoretical and Fundamental Chemistry |
Resource recovery as a solid fuel has been found to have high market potential in Sub-Saharan Africa. The selection of the fuel type will depend on: (1) the intended use of the fuel (e.g. combustion technology, user/handling requirements, and amount required); and (2) the properties of the input fecal sludge (e.g. level of stabilization, sand content, and moisture content). Once suitable technology options are identified, they must subsequently be evaluated for best fit in the local context (e.g. local capacity for electricity, land, and technical (operation and maintenance) requirements). | 1 | Applied and Interdisciplinary Chemistry |
Radium and radon are important contributors to environmental radioactivity. Radon occurs naturally as a result of decay of radioactive elements in soil and it can accumulate in houses built on areas where such decay occurs. Radon is a major cause of cancer; it is estimated to contribute to ~2% of all cancer related deaths in Europe.
Radium, like radon, is radioactive and is found in small quantities in nature and is hazardous to life if radiation exceeds 20-50 mSv/year. Radium is a decay product of uranium and thorium. Radium may also be released into the environment by human activity, for example, in improperly discarded products painted with radioluminescent paint. | 0 | Theoretical and Fundamental Chemistry |
Electrohydrodynamics (EHD), also known as electro-fluid-dynamics (EFD) or electrokinetics, is the study of the dynamics of electrically charged fluids. It is the study of the motions of ionized particles or molecules and their interactions with electric fields and the surrounding fluid. The term may be considered to be synonymous with the rather elaborate electrostrictive hydrodynamics. ESHD covers the following types of particle and fluid transport mechanisms: electrophoresis, electrokinesis, dielectrophoresis, electro-osmosis, and electrorotation. In general, the phenomena relate to the direct conversion of electrical energy into kinetic energy, and vice versa.
In the first instance, shaped electrostatic fields (ESF's) create hydrostatic pressure (HSP, or motion) in dielectric media. When such media are fluids, a flow is produced. If the dielectric is a vacuum or a solid, no flow is produced. Such flow can be directed against the electrodes, generally to move the electrodes. In such case, the moving structure acts as an electric motor. Practical fields of interest of EHD are the common air ioniser, electrohydrodynamic thrusters and EHD cooling systems.
In the second instance, the converse takes place. A powered flow of medium within a shaped electrostatic field adds energy to the system which is picked up as a potential difference by electrodes. In such case, the structure acts as an electrical generator. | 1 | Applied and Interdisciplinary Chemistry |
In molecular biology, the protein domain S-adenosylmethionine synthetase, C-terminal domain refers to the C terminus of the S-adenosylmethionine synthetase | 1 | Applied and Interdisciplinary Chemistry |
The zirconium-catalyzed asymmetric carbo-alumination reaction (or ZACA reaction) was developed by Nobel laureate Ei-ichi Negishi. It facilitates the chiral functionalization of alkenes using organoaluminium compounds under the influence of chiral bis-indenylzirconium catalysts (e.g. bearing chiral terpene residues, as in (+)- or (−)-bis[(1-neomenthyl)indenyl]zirconium dichloride). In a first step the alkene inserts into an Al-C bond of the reagent, forming a new chiral organoaluminium compound in which the aluminium atom occupies the lesser hindered position. This intermediate is usually oxidized by oxygen to form the corresponding chiral alcohol (cf. hydroboration–oxidation reaction). The reaction can also be applied to dienes, where the least sterically hindered double bond is attacked selectively. | 0 | Theoretical and Fundamental Chemistry |
Effluent is wastewater from sewers or industrial outfalls that flows directly into surface waters, either untreated or after being treated at a facility. The term has slightly different meanings in certain contexts, and may contain various pollutants depending on the source. | 1 | Applied and Interdisciplinary Chemistry |
The British Non-Ferrous Metals Research Association was a research group in the United Kingdom during the 20th century, bringing together public and privately funded research into metallurgy. The name was abbreviated officially to B.N.F.M.R.A. (the organisation was normally known as ‘The BNF’ during its life). It was formed in 1920 by members of the British Non-Ferrous Metals Federation which represented the commercial interests of British manufacturers of coppers and copper alloys, lead, zinc and other non-ferrous metals and their alloys, latterly including titanium. Robert Hutton was appointed director in 1921. | 1 | Applied and Interdisciplinary Chemistry |
In mass spectroscopy based proteomics there are three major steps needed for peptide identification: sample preparation, separation of peptides, and identification of peptides. Several groups have focused on oocytes or very early cleavage-stage cells since these cells are unusually large and provide enough material for analysis. Another approach, single cell proteomics by mass spectrometry (SCoPE-MS) has quantified thousands of proteins in mammalian cells with typical cell sizes (diameter of 10-15 μm) by combining carrier-cells and single-cell barcoding. The second generation, SCoPE2, increased the throughput by automated and miniaturized sample preparation; It also improved quantitative reliability and proteome coverage by data-driven optimization of LC-MS/MS and peptide identification. The sensitivity and consistency of these methods have been further improved by prioritization, and massively parallel sample preparation in nanoliter size droplets. Another direction for single-cell protein analysis is based on a scalable framework of multiplexed data-independent acquisition (plexDIA) enables time saving by parallel analysis of both peptide ions and protein samples, thereby realizing multiplicative gains in throughput.
The separation of differently sized proteins can be accomplished by using capillary electrophoresis (CE) or liquid chromatography (LC) (using liquid chromatography with mass spectroscopy is also known as LC-MS). This step gives order to the peptides before quantification using tandem mass-spectroscopy (MS/MS). The major difference between quantification methods is some use labels on the peptides such as tandem mass tags (TMT) or dimethyl labels which are used to identify which cell a certain protein came from (proteins coming from each cell have a different label) while others use not labels (quantify cells individually). The mass spectroscopy data is then analyzed by running data through databases that convert the information about peptides identified to quantification of protein levels. These methods are very similar to those used to quantify the proteome of bulk cells, with modifications to accommodate the very small sample volume. | 1 | Applied and Interdisciplinary Chemistry |
In thermodynamics, when is exact, the function is a state function of the system: a mathematical function which depends solely on the current equilibrium state, not on the path taken to reach that state. Internal energy , Entropy , Enthalpy , Helmholtz free energy , and Gibbs free energy are state functions. Generally, neither work nor heat is a state function. (Note: is commonly used to represent heat in physics. It should not be confused with the use earlier in this article as the parameter of an exact differential.) | 0 | Theoretical and Fundamental Chemistry |
The photochromic trans-cis isomerization of azobenzenes has been used extensively in molecular switches, often taking advantage of its shape change upon isomerization to produce a supramolecular result. In particular, azobenzenes incorporated into crown ethers give switchable receptors and azobenzenes in monolayers can provide light-controlled changes in surface properties. | 0 | Theoretical and Fundamental Chemistry |
The student was not allowed to use notes, textbooks, or a calculator on this test. The only resource a student could use was a periodic table which was provided with the test booklet. This table only provided atomic masses, atomic numbers, and symbols for each element. | 1 | Applied and Interdisciplinary Chemistry |
Parvoviruses are linear, non-segmented single-stranded DNA viruses, with an average genome size of 5000 nucleotides. They are classified as group II viruses in Baltimore classification of viruses. Parvoviruses are among the smallest viruses (hence the name, from Latin parvus meaning small) and are 18–28 nm in diameter.
Parvoviruses can cause disease in some animals, including starfish and humans. Because the viruses require actively dividing cells to replicate, the type of tissue infected varies with the age of the animal. The gastrointestinal tract and lymphatic system can be affected at any age, leading to vomiting, diarrhea and immunosuppression but cerebellar hypoplasia is only seen in cats that were infected in the womb or at less than two weeks of age, and disease of the myocardium is seen in puppies infected between the ages of three and eight weeks. | 1 | Applied and Interdisciplinary Chemistry |
Hattori began her academic career as a postdoctoral researcher at the University of Alberta in Edmonton in 1977 and participated in the International Drilling project as a Canadian delegate to study volcanic rocks and thermal alteration in Iceland. In 1980, she moved to the University of Calgary as a Research Associate jointly affiliated with the Department of Physics and the Department of Geology and Geophysics. Three years later, she joined the University of Ottawa as an Assistant Professor and was promoted to Associate Professor in the Department of Geology in 1987.
She was the first female Professor in earth science departments within the national capital region as well as the first female Professor of mineral deposits in Canada. In 1994 she became Full Professor in the Department of Earth and Environmental Sciences at the University of Ottawa. She was awarded the title of Distinguished University Professor in 2023 for her contributions to scientific research and education.
Hattori has held numerous administrative appointments throughout her career. From July 1991 to June 1994, she served as the Director of the Ottawa-Carleton Geoscience Centre. In 2004, she was appointed as the department chair for Earth Sciences at the University of Ottawa, a position she held for four years.
Apart from the administrative work related to universities, she has been engaged in the activities of several scientific organizations including Mineralogical Society of America, Society of Economic Geologists, and Royal Society of Canada. She is Director of Earth, Ocean and Atmosphere Science Division of Royal Society of Canada (2021-2024).
Hattori was an appraiser of graduate-research programs at various Ontario Universities (1999-2002) and geoscience program reviewers of American University of Beirut in Lebanon (2016-17), Western University (2012) and Hiroshima University (2009).
Hattori has been appointed as Visiting Professor at Université de Lyon (1999) and l’Universiteé Grenoble (2016), Visiting Scientist at Japan Marine Science and Technology (2003-2004), Visiting Professor at Nagoya Institute, Guest Research Scientists at Woods Hole Oceanographic Institution (1995-1996), Visiting Research Scientist at Massachusetts Institute of Technology (1989-1990). | 0 | Theoretical and Fundamental Chemistry |
Several groups of animals have formed symbiotic relationships with photosynthetic algae. These are most common in corals, sponges and sea anemones. It is presumed that this is due to the particularly simple body plans and large surface areas of these animals compared to their volumes. In addition, a few marine mollusks Elysia viridis and Elysia chlorotica also maintain a symbiotic relationship with chloroplasts they capture from the algae in their diet and then store in their bodies. This allows the mollusks to survive solely by photosynthesis for several months at a time. Some of the genes from the plant cell nucleus have even been transferred to the slugs, so that the chloroplasts can be supplied with proteins that they need to survive.
An even closer form of symbiosis may explain the origin of chloroplasts. Chloroplasts have many similarities with photosynthetic bacteria, including a circular chromosome, prokaryotic-type ribosomes, and similar proteins in the photosynthetic reaction center. The endosymbiotic theory suggests that photosynthetic bacteria were acquired (by endocytosis) by early eukaryotic cells to form the first plant cells. Therefore, chloroplasts may be photosynthetic bacteria that adapted to life inside plant cells. Like mitochondria, chloroplasts still possess their own DNA, separate from the nuclear DNA of their plant host cells and the genes in this chloroplast DNA resemble those in cyanobacteria. DNA in chloroplasts codes for redox proteins such as photosynthetic reaction centers. The CoRR Hypothesis proposes that this Co-location is required for Redox Regulation. | 0 | Theoretical and Fundamental Chemistry |
Both Spanish (sacamantecas) and Peruvian (pishtaco) folklore contain examples of monsters or criminals who murder human victims for their fat.
Manuel Blanco Romasanta (1809–1863), the first serial killer documented in Spain, was accused of extracting fat from his victims to sell in Portugal, exchanging an ounce of fat for an ounce of gold.
This folk belief survives to the modern day. In Latin American urban legends, it is claimed that human fat is used to grease bells for better sound, or applied to modern machinery such as railways or airplanes. | 1 | Applied and Interdisciplinary Chemistry |
The belt-type machine is generally more applicable to smaller and to adhesive feed. In addition, the feed presentation is more stable which makes it more applicable for more difficult and heterogenous applications. | 0 | Theoretical and Fundamental Chemistry |
By the use of selective radioactively labeled agonist and antagonist substances, five subtypes of muscarinic receptors have been determined, named M–M (using an upper case M and subscript number). M, M, M receptors are coupled with G proteins, while M and M receptors are coupled with G proteins. There are other classification systems. For example, the drug pirenzepine is a muscarinic antagonist (decreases the effect of ACh), which is much more potent at M receptors than it is at other subtypes. The acceptance of the various subtypes proceeded in numerical order, therefore, earlier sources may recognize only M and M subtypes, while later studies recognize M, M,[http://www.guidetopharmacology.org/GRAC/FamilyDisplayForward?familyId=2] and most recently M subtypes. | 1 | Applied and Interdisciplinary Chemistry |
Miraculin was first sequenced in 1989 and was found to be a 24.6 kilodalton glycoprotein consisting of 191 amino acids and 13.9% by weight of various sugars.
The sugars consist of a total of 3.4 kDa, composed of a molar ratio of glucosamine (31%), mannose (30%), fucose (22%), xylose (10%), and galactose (7%).
The native state of miraculin is a tetramer consisting of two dimers, each held together by a disulfide bridge. Both tetramer miraculin and native dimer miraculin in its crude state have the taste-modifying activity of turning sour tastes into sweet tastes. Miraculin belongs to the Kunitz STI protease inhibitor family. | 1 | Applied and Interdisciplinary Chemistry |
A provitamin is a substance that may be converted within the body to a vitamin. The term previtamin is a synonym.
The term "provitamin" is used when it is desirable to label a substance with little or no vitamin activity, but which can be converted to an active form by normal metabolic processes. | 1 | Applied and Interdisciplinary Chemistry |
Sevoflurane has an excellent safety record, but is under review for potential hepatotoxicity, and may accelerate Alzheimer's. There were rare reports involving adults with symptoms similar to halothane hepatotoxicity. Sevoflurane is the preferred agent for mask induction due to its lesser irritation to mucous membranes.
Sevoflurane is an inhaled anaesthetic that is often used to induction and maintenance of anaesthesia in children for surgery. During the process of awakening from the medication, it has been associated with a high incidence (>30%) of agitation and delirium in preschool children undergoing minor noninvasive surgery. It is not clear if this can be prevented.
Studies examining a current significant health concern, anesthetic-induced neurotoxicity (including with sevoflurane, and especially with children and infants) are "fraught with confounders, and many are underpowered statistically", and so are argued to need "further data... to either support or refute the potential connection".
Concern regarding the safety of anaesthesia is especially acute with regard to children and infants, where preclinical evidence from relevant animal models suggest that common clinically important agents, including sevoflurane, may be neurotoxic to the developing brain, and so cause neurobehavioural abnormalities in the long term; two large-scale clinical studies (PANDA and GAS) were ongoing as of 2010, in hope of supplying "significant [further] information" on neurodevelopmental effects of general anaesthesia in infants and young children, including where sevoflurane is used.
In 2021, researchers at Massachusetts General Hospital published in Communications Biology research that sevoflurane may accelerate existing Alzheimer's or existing tau protein to spread: "These data demonstrate anesthesia-associated tau spreading and its consequences. [...] This tau spreading could be prevented by inhibitors of tau phosphorylation or extracellular vesicle generation." According to Neuroscience News, "Their previous work showed that sevoflurane can cause a change (specifically, phosphorylation, or the addition of phosphate) to tau that leads to cognitive impairment in mice. Other researchers have also found that sevoflurane and certain other anesthetics may affect cognitive function."
Additionally, there has been some investigation into potential correlation of sevoflurane use and renal damage (nephrotoxicity). However, this should be subject to further investigation, as a recent study shows no correlation between sevoflurane use and renal damage as compared to other control anesthetic agents. | 1 | Applied and Interdisciplinary Chemistry |
The British "Radiac Survey Meter No. 2" dates from 1953 to 1956, and required now-obsolete 15 and 30 volt high voltage batteries and a 1.5 volt standard cell, the latter used to power the valve heater filaments and meter illumination bulb. There was also a training unit, which measured 0–300 mR/h, and ran on four 30 volt batteries plus one 1.5 V cell for the filaments. This meter used a large Geiger–Müller tube, as opposed to the ionisation chamber of the RSM No. 2.
These meters were favoured, as they had been tested on fallout in Australia after Operation Buffalo nuclear tests, and were retained until 1982 by commissioning a manufacturer to regularly produce special production runs of the obsolete batteries.
The UK's Royal Observer Corps (ROC) initially used the RSM No. 2 as its prime radiation detector until it was replaced by the specially-designed "Fixed Survey Meter", which used the same obsolete high voltage batteries as the RSM. The ROC retained the RSM No. 2 for use during external "post-attack" mobile monitoring surveys. | 0 | Theoretical and Fundamental Chemistry |
The classic example of an IEC device is a fusor. A typical Fusor has two spherical metal cages, one inside another, in a vacuum. A high voltage is placed between the two cages. Fuel gas injected. The fuel ionizes and is accelerated toward the inner cage. Ions that miss the inner cage can fuse together.
Fusors are not considered part of the CBFR family, because they do not traditionally use beams.
There are many problems with the fusor as a fusion power reactor. One is that the electrical grids are charged to the point where there is a strong mechanical force pulling them together, which limits how small the grid materials can be. This results in a minimum rate of collisions between the ions and the grids, removing energy from the system. Additionally, these collisions spall off metal into the fuel, which causes it to rapidly lose energy through radiation. It may be that the smallest possible grid material is still large enough that collisions with the ions will remove energy from the system faster than the fusion rate. Beyond that, there are several loss mechanisms that suggest X-ray radiation from such a system will likewise remove energy faster than fusion can supply it. | 0 | Theoretical and Fundamental Chemistry |
The indenyl analogues of ferrocene, which is orange, and cobaltocenium cation were first reported by Pauson and Wilkinson. The cobalt derivative is a poorer reductant than cobaltocene.
The indenyl effect was discovered by Hart-Davis and Mawby in 1969 through studies on the conversion of (η-CH)Mo(CO)CH to the phosphine-substituted acetyl complex, which follows bimolecular kinetics. This rate law was attributed to the haptotropic rearrangement of the indenyl ligand from η to η. The corresponding reaction of tributylphosphine with (η-CH)Mo(CO)CH was 10 x slower. The term indenyl effect was coined by Fred Basolo.
Subsequent work by Hart-Davis, Mawby, and White compared CO substitution by phosphines in Mo(η-CH)(CO)X and Mo(η-CH)(CO)X (X = Cl, Br, I) and found the cyclopentadienyl compounds to substitute by an S1 pathway and the indenyl compounds to substitute by both S1 and S2 pathways. Mawby and Jones later studied the rate of CO substitution with P(OEt) with Fe(η-CH)(CO)I and Fe(η-CH)(CO)I and found that both occur by an S1 pathway with the indenyl substitution occurring about 575 times faster. Hydrogenation of the arene ring in the indenyl ligand resulted in CO substitution at about half the rate of the cyclopentadienyl compound.
Work in the early 1980s by Basolo found the S2 replacement of CO in Rh(η-CH)(CO) to be 10 times faster than in Rh(η-CH)(CO). Shortly afterwards, Basolo tested the effect of the indene ligand on Mn(η-CH)(CO), the cyclopentadienyl analogue of which having been shown to be inert to CO substitution. Mn(η-CH)(CO) did undergo CO loss and was found to substitute via an S2 mechanism. | 0 | Theoretical and Fundamental Chemistry |
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