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The reaction mechanism centers around the formation of an iminophosphorane through nucleophilic addition of the aryl or alkyl phosphine at the terminal nitrogen atom of the organic azide and expulsion of diatomic nitrogen. The iminophosphorane is then hydrolyzed in the second step to the amine and a phosphine oxide byproduct. | 0 | Theoretical and Fundamental Chemistry |
Cyclic silyl enol ethers undergo regiocontrolled one-carbon ring contractions. These reactions employ electron-deficient sulfonyl azides, which undergo chemoselective, uncatalyzed [3+2] cycloaddition to the silyl enol ether, followed by loss of dinitrogen, and alkyl migration to give ring-contracted products in good yield. These reactions may be directed by substrate stereochemistry, giving rise to stereoselective ring-contracted product formation. | 0 | Theoretical and Fundamental Chemistry |
GaN dust is an irritant to skin, eyes and lungs. The environment, health and safety aspects of gallium nitride sources (such as trimethylgallium and ammonia) and industrial hygiene monitoring studies of MOVPE sources have been reported in a 2004 review.
Bulk GaN is non-toxic and biocompatible. Therefore, it may be used in the electrodes and electronics of implants in living organisms. | 0 | Theoretical and Fundamental Chemistry |
Alcohols add to electrophilically activated alkenes. The method is atom-economical:
: RC=CR + R–OH → RCH–C(–O–R)–R
Acid catalysis is required for this reaction. Commericially important ethers prepared in this way are derived from isobutene or isoamylene, which protonate to give relatively stable carbocations. Using ethanol and methanol with these two alkenes, four fuel-grade ethers are produced: methyl tert-butyl ether (MTBE), methyl tert-amyl ether (TAME), ethyl tert-butyl ether (ETBE), and ethyl tert-amyl ether (TAEE).
Solid acid catalysts are typically used to promote this reaction. | 0 | Theoretical and Fundamental Chemistry |
cDNA library lacks the non-coding and regulatory elements found in genomic DNA. Genomic DNA libraries provide more detailed information about the organism, but are more resource-intensive to generate and keep. | 1 | Applied and Interdisciplinary Chemistry |
Her research involves structural characterization of biopolymers using mass spectrometry-based techniques, such as liquid chromatography-mass spectrometry, thin-layer chromatography-mass spectrometry, Fourier-transform ion cyclotron resonance mass spectrometry, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, microfluidic capillary electrophoresis-mass spectrometry, and ion mobility spectrometry-mass spectrometry. She was one of the first scientists to characterize glycoconjugates with tandem mass spectrometry. Her 1988 article has been cited over two thousand times. She participated in the Human Proteome Project, the SysteMHC Atlas project, and the Minimum Information Required for a Glycomics Experiment (MIRAGE) project. | 1 | Applied and Interdisciplinary Chemistry |
Under the Acronym Biofector the European Union supports the Research of Bioeffectors under the leadership of the University of Hohenheim. Coordinator Guenter Neumann, Projectmembers: Jiří Balík, Borbala Biro, Karl Fritz Lauer, Uwe Ludewig, Torsten Müller, Alessandro Piccolo, Manfred G. Raupp, Kornelia Smalla, Pavel Tlustoš, Markus Weinmann.
The results of the project will be evaluated by the members of the Association Biostimulants in Agriculture (ABISTA) and provided agriculture for use and EU institutions for the legislative and registration procedures.
Other Biostimulants Organisations are European Biostimulant Industry Council, International Biocontrol Manufacturers' Association and Annual Biocontrol Industry Meeting. | 1 | Applied and Interdisciplinary Chemistry |
T5 lamps are approximately 40% smaller than T8 Lamps. T5 lamps have a G5 base while T8 lamps use a G13 base. | 1 | Applied and Interdisciplinary Chemistry |
Thylakoids (sometimes spelled thylakoïds), are small interconnected sacks which contain the membranes that the light reactions of photosynthesis take place on. The word thylakoid comes from the Greek word thylakos which means "sack".
Suspended within the chloroplast stroma is the thylakoid system, a highly dynamic collection of membranous sacks called thylakoids where chlorophyll is found and the light reactions of photosynthesis happen.
In most vascular plant chloroplasts, the thylakoids are arranged in stacks called grana, though in certain plant chloroplasts and some algal chloroplasts, the thylakoids are free floating. | 0 | Theoretical and Fundamental Chemistry |
Effective 18 August 2014, tramadol has been placed into Schedule IV of the federal Controlled Substances Act in the United States. Before that, some US states had already classified tramadol as a Schedule IV controlled substance under their respective state laws.
Tramadol is classified in Schedule 4 (prescription only) in Australia, rather than as a Schedule 8 Controlled Drug (Possession without authority illegal) like most other opioids.
Effective May 2008, Sweden classified tramadol as a controlled substance in the same category as codeine and dextropropoxyphene, but allows a normal prescription to be used.
On 10 June 2014, the United Kingdom's Home Office classified tramadol as a Class C, Schedule 3 controlled drug, but exempted it from the safe custody requirement.
On 1 October 2023, New Zealand's Medsafe reclassified tramadol as a Class C2 Controlled Drug (in addition to its existing status as a prescription only medication). | 0 | Theoretical and Fundamental Chemistry |
Common side effects include headache, dizziness, feeling tired, cough, nausea, and rash. Serious side effects may include low blood pressure, liver problems, hyperkalemia, and angioedema. Use is not recommended during the entire duration of pregnancy as it may harm the baby. | 0 | Theoretical and Fundamental Chemistry |
Among the TrkA agonists, the small molecule gambogic amide exerts a potent neurotrophic activity decreasing apoptosis in primary hippocampal neurons. The non-peptidic TrkA agonist MT2 protects neurons from Aβ amyloid-mediated death in NGF-deficient neurons and talaumidin and its derivatives show neuroprotective effects, promoting neurite outgrowth in PC12 cells. Furthermore, the peptidomimetic cerebrolysin is known for its protective role in Alzheimer’s disease (AD). It was shown to improve the activities of daily living and the psychiatric symptoms in patients with mild to severe form of AD, after intravenous administration in a double-blind trial. In addition, the cyclic peptide tavilermide (MIM-D3), acting as a partial TrkA receptor agonist, showed a relevant improvement of cognitive capacities of treated aged rats, leading to a selective survival of the cholinergic neurons.
A phase 3 clinical trial of 5% and 1% tavilermide ophthalmic solutions for the treatment of dry eye was completed in 2020 (NCT03925727), with positive results concerning safety and efficacy. Recent studies demonstrated the neurotrophic activity of carvacrol by inducing neurite outgrowth and phosphorylation of TrkA in cells deprived of NGF. The same research group investigated the neurotrophic effect of the well-known antibiotic doxycycline and they found that it prevents amyloid toxicity in a Drosophila model of AD both in vitro and in vivo and induces neuritogenesis by activation of TrkA.
Additionally, some novel DHEA derivatives were shown to be TrkA agonists. In particular, the C17-spiroepoxy derivative, BNN-27, induces phosphorylation of TrkA in neuronal and glial cells in culture and it exerts antiapoptotic effect without inducing hyperalgesia. Moreover, it improved memorizing abilities in rats after i.p. administration and restored the myelin loss in cuprizone-induced demyelination in vivo. Moreover, the C17-spirocyclopryl DHEA derivatives, ENT-A010 and ENT-A013, were shown to be potent TrkA agonists. In particular, ENT-A010 acts as dual TrkA and TrkB agonist while, ENT-A013 acts as a selective TrkA agonist. Both induce phosphorylation of TrkA and its downstream signaling pathways, and promote cell survival of PC12 cells from serum deprivation. In addition, they exhibit potent neuroprotective effects in dorsal root ganglia and anti-amyloid activity in hippocampal neurons. | 1 | Applied and Interdisciplinary Chemistry |
Traditionally, ultrasound B-Mode imaging has been designed for allowing a visual evaluation of human organs and their features by clinicians; however, this implies that the huge quantity of information carried by ultrasound signals is processed and significantly reduced for visualization purposes. REMS technology instead analyses the raw, unfiltered ultrasound signals by comparing their spectral representation with the spectral models stored in a proprietary database which has been previously obtained from healthy and osteoporotic patients; these models are specific and vary with sex, age, BMI and skeletal site. The comparison allows the BMD estimation of the patient as well as a both fast and reliable diagnostic classification, compliant to the recommendations and diagnostic criteria defined by the World Health Organization. | 0 | Theoretical and Fundamental Chemistry |
In molecules whose vibrational mode involves a rotational or pseudorotational mechanism (such as the Berry mechanism or the Bartell mechanism), Van der Waals strain can cause significant differences in potential energy, even between molecules with identical geometry.
PF, for example, has significantly lower potential energy than PCl.
Despite their identical trigonal bipyramidal molecular geometry, the higher electron count of chlorine as compared to fluorine causes a potential energy spike as the molecule enters its intermediate in the mechanism and the substituents draw nearer to each other. | 0 | Theoretical and Fundamental Chemistry |
Metallacarboxylic acids exist in equilibria with the carboxylate anions, LMCO.
Metallacarboxylate esters (LMCOR) arise by the addition of alkoxide to metal carbonyl:
:[LM-CO] + ROH → [LM-COR] + H
Metallacarboxylic amides (LMC(O)NR) arise by the addition of amide to metal carbonyl:
:[LM-CO] + 2 RNH → [LM-C(O)N(H)R] + RNH
Derivatives of metalladithiacarboxylic acids are also known. They are prepared by treating anionic complexes with carbon disulfide. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, the Hass–Bender oxidation (also called the Hass–Bender carbonyl synthesis) is an organic oxidation reaction that converts benzyl halides into benzaldehydes using the sodium salt of 2-nitropropane as the oxidant. This name reaction is named for Henry B. Hass and Myron L. Bender, who first reported it in 1949.
The reaction process begins with the deprotonation of 2-nitropropane at the α carbon to form a nitronate. This compound then initiates an S2 reaction to displace the benzyl halide. Unlike in the nitroaldol reaction, where the deprotonated carbon of the nitroalkyl group is the nucleophilic atom, it is instead an oxygen of the nitro itself that attacks the benzylic carbon. The O-benzyl structure then undergoes a pericyclic reaction to produce a benzaldehyde, with dimethyloxime as a byproduct.
Although originally developed for benzyl compounds, the reaction also works for allyl halides, giving the respective α,β-enones and enals. | 0 | Theoretical and Fundamental Chemistry |
Within living things, isotopic labels (both radioactive and nonradioactive) can be used to probe how the complex web of reactions which makes up the metabolism of an organism converts one substance to another. For instance a green plant uses light energy to convert water and carbon dioxide into glucose by photosynthesis. If the oxygen in the water is labeled, then the label appears in the oxygen gas formed by the plant and not in the glucose formed in the chloroplasts within the plant cells.
For biochemical and physiological experiments and medical methods, a number of specific isotopes have important applications.
*Stable isotopes have the advantage of not delivering a radiation dose to the system being studied; however, a significant excess of them in the organ or organism might still interfere with its functionality, and the availability of sufficient amounts for whole-animal studies is limited for many isotopes. Measurement is also difficult, and usually requires mass spectrometry to determine how much of the isotope is present in particular compounds, and there is no means of localizing measurements within the cell.
*H (deuterium), the stable isotope of hydrogen, is a stable tracer, the concentration of which can be measured by mass spectrometry or NMR. It is incorporated into all cellular structures. Specific deuterated compounds can also be produced.
*N, a stable isotope of nitrogen, has also been used. It is incorporated mainly into proteins.
*Radioactive isotopes have the advantages of being detectable in very low quantities, in being easily measured by scintillation counting or other radiochemical methods, and in being localizable to particular regions of a cell, and quantifiable by autoradiography. Many compounds with the radioactive atoms in specific positions can be prepared, and are widely available commercially. In high quantities they require precautions to guard the workers from the effects of radiation—and they can easily contaminate laboratory glassware and other equipment. For some isotopes the half-life is so short that preparation and measurement is difficult.
By organic synthesis it is possible to create a complex molecule with a radioactive label that can be confined to a small area of the molecule. For short-lived isotopes such as C, very rapid synthetic methods have been developed to permit the rapid addition of the radioactive isotope to the molecule. For instance a palladium catalysed carbonylation reaction in a microfluidic device has been used to rapidly form amides and it might be possible to use this method to form radioactive imaging agents for PET imaging.
*H (tritium), the radioisotope of hydrogen, is available at very high specific activities, and compounds with this isotope in particular positions are easily prepared by standard chemical reactions such as hydrogenation of unsaturated precursors. The isotope emits very soft beta radiation, and can be detected by scintillation counting.
*C, carbon-11 is usually produced by cyclotron bombardment of N with protons. The resulting nuclear reaction is . Additionally, carbon-11 can also be made using a cyclotron; boron in the form of boric oxide is reacted with protons in a (p,n) reaction. Another alternative route is to react B with deuterons. By rapid organic synthesis, the C compound formed in the cyclotron is converted into the imaging agent which is then used for PET.
*C, carbon-14 can be made (as above), and it is possible to convert the target material into simple inorganic and organic compounds. In most organic synthesis work it is normal to try to create a product out of two approximately equal sized fragments and to use a convergent route, but when a radioactive label is added, it is normal to try to add the label late in the synthesis in the form of a very small fragment to the molecule to enable the radioactivity to be localised in a single group. Late addition of the label also reduces the number of synthetic stages where radioactive material is used.
*F, fluorine-18 can be made by the reaction of neon with deuterons, Ne reacts in a (d,He) reaction. It is normal to use neon gas with a trace of stable fluorine (F). The F acts as a carrier which increases the yield of radioactivity from the cyclotron target by reducing the amount of radioactivity lost by absorption on surfaces. However, this reduction in loss is at the cost of the specific activity of the final product. | 0 | Theoretical and Fundamental Chemistry |
DNA sequences of HBsAg were obtained from 180 patients, in which 51 were chronic HBV carrier and 129 newly diagnosed patients, and compared with consensus sequences built with 168 HBV sequences imported from GenBank. Literature review and BLOSUM scores were used to define potentially altered antigenicity. | 1 | Applied and Interdisciplinary Chemistry |
Creatinine (; from Ancient Greek: κρέας (kréas) flesh) is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body (depending on muscle mass). | 1 | Applied and Interdisciplinary Chemistry |
In case (c), the spin-orbit coupling is stronger than the coupling to the internuclear axis, and and from case (a) cannot be defined. Instead and combine to form , which has a projection along the internuclear axis of magnitude . Then , as in case (a).
The good quantum numbers in case (c) are , , and . Since is undefined for this case, the states cannot be described as , or . An example of Hund's case (c) is the lowest Π state of diiodine (I), which approximates more closely to case (c) than to case (a).
The selection rules for , and parity are valid as for cases (a) and (b), but there are no rules for and since these are not good quantum numbers for case (c). | 0 | Theoretical and Fundamental Chemistry |
The Manning formula or Manning's equation is an empirical formula estimating the average velocity of a liquid in an open channel flow (flowing in a conduit that does not completely enclose the liquid). However, this equation is also used for calculation of flow variables in case of flow in partially full conduits, as they also possess a free surface like that of open channel flow. All flow in so-called open channels is driven by gravity.
It was first presented by the French engineer in 1867, and later re-developed by the Irish engineer Robert Manning in 1890.
Thus, the formula is also known in Europe as the Gauckler–Manning formula or Gauckler–Manning–Strickler formula (after Albert Strickler).
The Gauckler–Manning formula is used to estimate the average velocity of water flowing in an open channel in locations where it is not practical to construct a weir or flume to measure flow with greater accuracy. Manning's equation is also commonly used as part of a numerical step method, such as the standard step method, for delineating the free surface profile of water flowing in an open channel. | 1 | Applied and Interdisciplinary Chemistry |
The basic apparatus comprises an optical microscope, a light source and some fluorescent probe. Fluorescent emission is contingent upon absorption of a specific optical wavelength or color which restricts the choice of lamps. Most commonly, a broad spectrum mercury or xenon source is used in conjunction with a color filter. The technique begins by saving a background image of the sample before photobleaching. Next, the light source is focused onto a small patch of the viewable area either by switching to a higher magnification microscope objective or with laser light of the appropriate wavelength. The fluorophores in this region receive high intensity illumination which causes their fluorescence lifetime to quickly elapse (limited to roughly 10 photons before extinction). Now the image in the microscope is that of a uniformly fluorescent field with a noticeable dark spot. As Brownian motion proceeds, the still-fluorescing probes will diffuse throughout the sample and replace the non-fluorescent probes in the bleached region. This diffusion proceeds in an ordered fashion, analytically determinable from the diffusion equation. Assuming a Gaussian profile for the bleaching beam, the diffusion constant D can be simply calculated from:
where w is the radius of the beam and t is the "Characteristic" diffusion time. | 1 | Applied and Interdisciplinary Chemistry |
The Navier–Stokes equations for steady flow, with zero viscosity and a body force corresponding to the Coriolis force, are
where is the fluid velocity, is the fluid density, and the pressure. If we assume that is a scalar potential and the advective term on the left may be neglected (reasonable if the Rossby number is much less than unity) and that the flow is incompressible (density is constant), the equations become:
where is the angular velocity vector. If the curl of this equation is taken, the result is the Taylor–Proudman theorem:
To derive this, one needs the vector identities
and
and
(because the curl of the gradient is always equal to zero).
Note that is also needed (angular velocity is divergence-free).
The vector form of the Taylor–Proudman theorem is perhaps better understood by expanding the dot product:
In coordinates for which , the equations reduce to
if . Thus, all three components of the velocity vector are uniform along any line parallel to the z-axis. | 1 | Applied and Interdisciplinary Chemistry |
The generalized Liñán's equation is given by
where and are constant reaction orders of fuel and oxidizer, respectively. | 1 | Applied and Interdisciplinary Chemistry |
These techniques employ electric currents to drive or enhance sintering. English engineer A. G. Bloxam registered in 1906 the first patent on sintering powders using direct current in vacuum. The primary purpose of his inventions was the industrial scale production of filaments for incandescent lamps by compacting tungsten or molybdenum particles. The applied current was particularly effective in reducing surface oxides that increased the emissivity of the filaments.
In 1913, Weintraub and Rush patented a modified sintering method which combined electric current with pressure. The benefits of this method were proved for the sintering of refractory metals as well as conductive carbide or nitride powders. The starting boron–carbon or silicon–carbon powders were placed in an electrically insulating tube and compressed by two rods which also served as electrodes for the current. The estimated sintering temperature was 2000 °C.
In the United States, sintering was first patented by Duval d'Adrian in 1922. His three-step process aimed at producing heat-resistant blocks from such oxide materials as zirconia, thoria or tantalia. The steps were: (i) molding the powder; (ii) annealing it at about 2500 °C to make it conducting; (iii) applying current-pressure sintering as in the method by Weintraub and Rush.
Sintering that uses an arc produced via a capacitance discharge to eliminate oxides before direct current heating, was patented by G. F. Taylor in 1932. This originated sintering methods employing pulsed or alternating current, eventually superimposed to a direct current. Those techniques have been developed over many decades and summarized in more than 640 patents.
Of these technologies the most well known is resistance sintering (also called hot pressing) and spark plasma sintering, while electro sinter forging is the latest advancement in this field. | 1 | Applied and Interdisciplinary Chemistry |
Eoxin E4, also known as 14,15-leukotriene E4, is an eoxin. Cells make eoxins by metabolizing arachidonic acid with a 15-lipoxygenase enzyme to form 15(S)-hydroperoxyeicosapentaenoic acid (i.e. 15(S)-HpETE). This product is then converted serially to eoxin A4 (i.e. EXA4), EXC4, EXD4, and EXE4 by LTC4 synthase, an unidentified gamma-glutamyltransferase, and an unidentified dipeptidase, respectively, in a pathway which appears similar if not identical to the pathway which forms leukotreines, i.e. LTA4, LTC4, LTD4, and LTE4. This pathway is schematically shown as follows:
EXA is viewed as an intracellular-bound, short-lived intermediate which is rapidly metabolized to the down-stream eoxins. The eoxins down stream of EXA4 are secreted from their parent cells and, it is proposed but not yet proven, serve to regulate allergic responses and the development of certain cancers (see Eoxins). | 1 | Applied and Interdisciplinary Chemistry |
Ion current density is typically measured in mA/cm, and ion energy in eV. The use of eV is convenient for converting between voltage and energy, especially when dealing with singly-charged ion beams, as well as converting between energy and temperature (1 eV = 11600 K). | 0 | Theoretical and Fundamental Chemistry |
Rotation axes are denoted by a number n – 1, 2, 3, 4, 5, 6, 7, 8, ... (angle of rotation ). For improper rotations, Hermann–Mauguin symbols show rotoinversion axes, unlike Schoenflies and Shubnikov notations, that shows rotation-reflection axes. The rotoinversion axes are represented by the corresponding number with a macron, – , , , , , , , , ... . is equivalent to a mirror plane and usually notated as m. The direction of the mirror plane is defined as the direction perpendicular to it (the direction of the axis).
Hermann–Mauguin symbols show non-equivalent axes and planes in a symmetrical fashion. The direction of a symmetry element corresponds to its position in the Hermann–Mauguin symbol. If a rotation axis n and a mirror plane m have the same direction (i.e. the plane is perpendicular to axis n), then they are denoted as a fraction or n/m.
If two or more axes have the same direction, the axis with higher symmetry is shown. Higher symmetry means that the axis generates a pattern with more points. For example, rotation axes 3, 4, 5, 6, 7, 8 generate 3-, 4-, 5-, 6-, 7-, 8-point patterns, respectively. Improper rotation axes , , , , , generate 6-, 4-, 10-, 6-, 14-, 8-point patterns, respectively. If a rotation and a rotoinversion axis generate the same number of points, the rotation axis should be chosen. For example, the combination is equivalent to . Since generates 6 points, and 3 generates only 3, should be written instead of (not , because already contains the mirror plane m). Analogously, in the case when both 3 and axes are present, should be written. However we write , not , because both 4 and generate four points. In the case of the combination, where 2, 3, 6, , and axes are present, axes , , and 6 all generate 6-point patterns, as we can see on the figure in the right, but the latter should be used because it is a rotation axis – the symbol will be
Finally, the Hermann–Mauguin symbol depends on the type of the group. | 0 | Theoretical and Fundamental Chemistry |
Protein separate techniques, such as 2D PAGE, are limited in that they cannot handle very high or low molecular weight protein species. Alternative methods have been developed to deal with such cases. These include liquid chromatography mass spectrometry along with sodium dodecyl sulfate polyacrylamide gel electrophoresis, or liquid chromatography mass spectrometry run in multiple dimensions. Compared to simple 2D page, liquid chromatography mass spectrometry can handle a larger range of protein species size, but it is limited in the amount of protein sample it handle at once. Liquid chromatography mass spectrometry is also limited in its lack of a reference map from which to work with. Complex algorithms are usually used to analyze the fringe results that occur after a procedure is run. The unknown portions of the protein species are usually not analyzed in favor of familiar proteomes, however. This fact reveals a fault with current technology; new techniques are needed to increase both the specificity and scope of proteome mapping. | 1 | Applied and Interdisciplinary Chemistry |
Retrofitting is the addition of new technology or features to older systems. Retrofits can happen for a number of reasons, for example with big capital expenditures like naval vessels, military equipment or manufacturing plants, businesses or governments may retrofit in order to reduce the need to replace a system entirely. Other retrofits may be due to changing codes or requirements, such as seismic retrofit which are designed strengthening older buildings in order to make them earthquake resistant.
Retrofitting is also an important part of climate change mitigation and climate change adaptation: because society invested in built infrastructure, housing and other systems before the magnitude of changes anticipated by climate change. Retrofits to increase building efficiency, for example, both help reduce the overall negative impacts of climate change by reducing building emissions and environmental impacts while also allowing the building to be more healthy during extreme weather events. Retrofitting also is part of a circular economy, reducing the amount of newly manufactured goods, thus reducing lifecycle emissions and environmental impacts. | 1 | Applied and Interdisciplinary Chemistry |
Silicon single crystals may be produced today in commercial facilities with extremely high purity and with few lattice defects. This method defined the Avogadro constant as the ratio of the molar volume, V, to the atomic volume V:
where and n is the number of atoms per unit cell of volume V.
The unit cell of silicon has a cubic packing arrangement of 8 atoms, and the unit cell volume may be measured by determining a single unit cell parameter, the length a of one of the sides of the cube. The 2018 CODATA value of a for silicon is .
In practice, measurements are carried out on a distance known as d(Si), which is the distance between the planes denoted by the Miller indices {220}, and is equal to .
The isotope proportional composition of the sample used must be measured and taken into account. Silicon occurs in three stable isotopes (Si, Si, Si), and the natural variation in their proportions is greater than other uncertainties in the measurements. The atomic weight A for the sample crystal can be calculated, as the standard atomic weights of the three nuclides are known with great accuracy. This, together with the measured density ρ of the sample, allows the molar volume V to be determined:
where M is the molar mass constant. The 2018 CODATA value for the molar volume of silicon is , with a relative standard uncertainty of . | 0 | Theoretical and Fundamental Chemistry |
Mutations in emerin cause X-linked recessive Emery–Dreifuss muscular dystrophy, which is characterized by early contractures in the Achilles tendons, elbows and post-cervical muscles; muscle weakness proximal in the upper limbs and distal in lower limbs; along with cardiac conduction defects that range from sinus bradycardia, PR prolongation to complete heart block. In these patients, immunostaining of emerin is lost in various tissues, including muscle, skin fibroblasts, and leukocytes, however diagnostic protocols involve mutational analysis rather than protein staining. In nearly all cases, mutations result in a complete deletion, or undetectable levels, of emerin protein. Approximately 20% of cases have X chromosomes with an inversion within the Xq28 region.
Moreover, recent research have found that the absence of functional emerin may decrease the infectivity of HIV-1. Thus, it is speculated that patients with Emery–Dreifuss muscular dystrophy may have immunity to or show an irregular infection pattern to HIV-1. | 1 | Applied and Interdisciplinary Chemistry |
[F]FDG, as a glucose analog, is taken up by high-glucose-using cells such as brain, brown adipocytes, kidney, and cancer cells, where phosphorylation prevents the glucose from being released again from the cell, once it has been absorbed. The 2-hydroxyl group (–OH) in normal glucose is needed for further glycolysis (metabolism of glucose by splitting it), but [F]FDG is missing this 2-hydroxyl. Thus, in common with its sister molecule 2-deoxy--glucose, FDG cannot be further metabolized in cells. The [F]FDG-6-phosphate formed when [F]FDG enters the cell cannot exit the cell before radioactive decay. As a result, the distribution of [F]FDG is a good reflection of the distribution of glucose uptake and phosphorylation by cells in the body.
The fluorine in [F]FDG decays radioactively via beta-decay to O. After picking up a proton H from a hydronium ion in its aqueous environment, the molecule becomes glucose-6-phosphate labeled with harmless nonradioactive "heavy oxygen" in the hydroxyl at the C-2 position. The new presence of a 2-hydroxyl now allows it to be metabolized normally in the same way as ordinary glucose, producing non-radioactive end-products.
Although in theory all [F]FDG is metabolized as above with a radioactivity elimination half-life of 110 minutes (the same as that of fluorine-18), clinical studies have shown that the radioactivity of [F]FDG partitions into two major fractions. About 75% of the fluorine-18 activity remains in tissues and is eliminated with a half-life of 110 minutes, presumably by decaying in place to O-18 to form [O]O-glucose-6-phosphate, which is non-radioactive (this molecule can soon be metabolized to carbon dioxide and water, after nuclear transmutation of the fluorine to oxygen ceases to prevent metabolism). Another fraction of [F]FDG, representing about 20% of the total fluorine-18 activity of an injection, is excreted renally by two hours after a dose of [F]FDG, with a rapid half-life of about 16 minutes (this portion makes the renal-collecting system and bladder prominent in a normal PET scan). This short biological half-life indicates that this 20% portion of the total fluorine-18 tracer activity is eliminated renally much more quickly than the isotope itself can decay. Unlike normal glucose, FDG is not fully reabsorbed by the kidney. Because of this rapidly excreted urine F, the urine of a patient undergoing a PET scan may therefore be especially radioactive for several hours after administration of the isotope.
All radioactivity of [F]FDG, both the 20% which is rapidly excreted in the first several hours of urine which is made after the exam, and the 80% which remains in the patient, decays with a half-life of 110 minutes (just under two hours). Thus, within 24 hours (13 half-lives after the injection), the radioactivity in the patient and in any initially voided urine which may have contaminated bedding or objects after the PET exam will have decayed to 2 = of the initial radioactivity of the dose. In practice, patients who have been injected with [F]FDG are told to avoid the close vicinity of especially radiation-sensitive persons, such as infants, children and pregnant women, for at least 12 hours (7 half-lives, or decay to the initial radioactive dose). | 1 | Applied and Interdisciplinary Chemistry |
After completing his PhD, Philipp Kukura moved to Zürich. There he worked at the Swiss Federal Institute of Technology as a postdoctoral research assistant under the supervision of Professor Vahid Sandoghdar on nano-optics until 2010. He returned to Oxford in 2010 to work initially as an EPSRC Career Acceleration Fellow. In 2011 he was elected to a tutorial fellowship at Exeter College. In 2016 he was promoted to Full Professor of Chemistry.
In 2018 Philipp Kukura founded Refeyn Ltd. together with Justin Benesch, Daniel Cole, and Gavin Young to commercialise mass photometry. | 0 | Theoretical and Fundamental Chemistry |
Unlike ideal surfaces, real surfaces do not have perfect smoothness, rigidity, or chemical homogeneity. Such deviations from ideality result in phenomenon called contact angle hysteresis, which is defined as the difference between the advancing (θ) and receding (θ) contact angles
When the contact angle is between the advancing and receding cases, the contact line is considered to be pinned and hysteretic behaviour can be observed, namely contact angle hysteresis. When these values are exceeded, the displacement of the contact line, such as the one in Figure 3, will take place by either expansion or retraction of the droplet. Figure 6 depicts the advancing and receding contact angles. The advancing contact angle is the maximum stable angle, whereas the receding contact angle is the minimum stable angle. Contact angle hysteresis occurs because many different thermodynamically stable contact angles are found on a nonideal solid. These varying thermodynamically stable contact angles are known as metastable states.
Such motion of a phase boundary, involving advancing and receding contact angles, is known as dynamic wetting. The difference between dynamic and static wetting angles is proportional to the capillary number, , When a contact line advances, covering more of the surface with liquid, the contact angle is increased and is generally related to the velocity of the contact line. If the velocity of a contact line is increased without bound, the contact angle increases, and as it approaches 180°, the gas phase will become entrained in a thin layer between the liquid and solid. This is a kinetic nonequilibrium effect which results from the contact line moving at such a high speed that complete wetting cannot occur.
A well-known departure from ideal conditions is when the surface of interest has a rough texture. The rough texture of a surface can fall into one of two categories: homogeneous or heterogeneous. A homogeneous wetting regime is where the liquid fills in the grooves of a rough surface. A heterogeneous wetting regime, though, is where the surface is a composite of two types of patches. An important example of such a composite surface is one composed of patches of both air and solid. Such surfaces have varied effects on the contact angles of wetting liquids. Cassie–Baxter and Wenzel are the two main models that attempt to describe the wetting of textured surfaces. However, these equations only apply when the drop size is sufficiently large compared with the surface roughness scale. When the droplet size is comparable to that of the underlying pillars, the effect of line tension should be considered. | 0 | Theoretical and Fundamental Chemistry |
A majority of cellular proteins are translated and folded in the cytosol with the help of molecular chaperones. Just as proteins must be folded to function in the cytosol, proteins in organelles like the endoplasmic reticulum (ER) and mitochondria also must be folded to function. Consequently, specific cellular mechanisms exist that aim to detect cellular stress (causing misfolded/unfolded proteins to accumulate), transduce the signal to the nucleus, and mediate the restoration of protein homeostasis (proteostasis). In the cytosol, the heat shock response (HSR) manages the unfolded proteins through heat shock factor 1 (HSF1). HSF-1 is a transcription factor that, upon increases in unfolded cytosolic proteins, will trimerize and enter the nucleus to upregulate the expression of heat shock proteins (HSPs) that will act as protein folding chaperones.
In organelles like the ER and mitochondria, the response is slightly more complex. Both UPR mechanisms are conceptually similar in that they are activated by the accumulation of misfolded/ unfolded proteins and induce the translational upregulation of molecular chaperones and proteases to process proteins and restore homeostasis. Despite their names, the two pathways possess distinct initiating stimuli and signaling mechanisms that regulate the responses. The ER UPR is induced by a variety of cellular stressors that inhibit protein folding or exit of the ER. Within the ER GRP78, an ER lumen chaperone, is bound to ER membrane proteins. When unfolded proteins build up, it dissociates to from the membrane to aid in protein folding. GRP78 dissociation triggers the UPR that restores protein homeostasis via three pathways (IRE1, PERK, and ATF6). The UPR restores proteostasis by selectively attenuation protein translation, upregulating protein folding chaperones, and degrading excess misfolded proteins via ER associated protein degradation (ERAD). Prolonged activation of the UPR can result in apoptosis.
The UPR progresses through the bZIP transcription factor ATFS-1 (in C. elegans; ATF5 in mammals). AFTS-1 is usually imported into the mitochondria where it is degraded by the LON protease. Mitochondrial dysfunction inhibits this process and allows ATFS-1 to accumulate in the cytosol and enter the nucleus where it can act as a transcription factor. This responses restores proteostasis by upregulating chaperones and proteases, increasing reactive oxygen species (ROS) detoxification, and increasing mitochondrial import machinery. | 1 | Applied and Interdisciplinary Chemistry |
MIKE 11 is a computer program that simulates flow and water level, water quality and sediment transport in rivers, flood plains, irrigation canals, reservoirs and other inland water bodies. MIKE 11 is a 1-dimensional river model. It was developed by DHI.
MIKE 11 has long been known as a software tool with advanced interface facilities.
Since the beginning MIKE 11 was operated through an efficient interactive menu system with systematic layouts and sequencing of menus. It is within that framework where the latest ‘Classic’ version of MIKE 11 – version 3.20 was developed.
The new generation of MIKE 11 combines the features and experiences from the mike11
MIKE 11 ‘Classic’ period, with the powerful Windows based user interface including graphical editing facilities and improved computational speed gained by the full utilization of 32-bit technology. | 1 | Applied and Interdisciplinary Chemistry |
The system of DNA profiling used today is based on polymerase chain reaction (PCR) and uses simple sequences.
From country to country, different STR-based DNA-profiling systems are in use. In North America, systems that amplify the CODIS 20 core loci are almost universal, whereas in the United Kingdom the DNA-17 loci system is in use, and Australia uses 18 core markers.
The true power of STR analysis is in its statistical power of discrimination. Because the 20 loci that are currently used for discrimination in CODIS are independently assorted (having a certain number of repeats at one locus does not change the likelihood of having any number of repeats at any other locus), the product rule for probabilities can be applied. This means that, if someone has the DNA type of ABC, where the three loci were independent, then the probability of that individual having that DNA type is the probability of having type A times the probability of having type B times the probability of having type C. This has resulted in the ability to generate match probabilities of 1 in a quintillion (1x10) or more. However, DNA database searches showed much more frequent than expected false DNA profile matches. | 1 | Applied and Interdisciplinary Chemistry |
* Rockefeller Public Service Award (1953)
* Society of Women Engineers Achievement Award (1966)
* Businessweek’s list of 100 Top Corporate Women (1976) | 0 | Theoretical and Fundamental Chemistry |
Essentially, Hox genes contribute to the specification of three main components of limb development, including the stylopod, zeugopod and autopod. Certain mutations in Hox genes can potentially lead to the proximal and/or distal losses along with different abnormalities. Three different models have been created for outlining the patterning of these regions. The Zone of polarizing activity (ZPA) in the limb bud has pattern-organizing activity through the utilization of a morphogen gradient of a protein called Sonic hedgehog (Shh). Sonic hedgehog is turned on in the posterior region via the early expression of HoxD genes, along with the expression of Hoxb8. Shh is maintained in the posterior through a feedback loop between the ZPA and the AER. Shh cleaves the Ci/Gli3 transcriptional repressor complex to convert the transcription factor Gli3 to an activator, which activates the transcription of HoxD genes along the anterior/posterior axis. It is evident that different Hox genes are critical for proper limb development in different amphibians.
Researchers conducted a study targeting the Hox-9 to Hox-13 genes in different species of frogs and other amphibians. Similar to an ancient tetrapod group with assorted limb types, it is important to note that amphibians are required for the understanding of the origin and diversification of limbs in different land vertebrates. A PCR (Polymerase Chain Reaction) study was conducted in two species of each amphibian order to identify Hox-9 to Hox-13. Fifteen distinct posterior Hox genes and one retro-pseudogene were identified, and the former confirm the existence of four Hox clusters in each amphibian order. Certain genes expected to occur in all tetrapods, based on the posterior Hox complement of mammals, fishes and coelacanth, were not recovered. HoxD-12 is absent in frogs and possibly other amphibians. By definition, the autopodium is distal segment of a limb, comprising the hand or foot. Considering Hox-12’s function in autopodium development, the loss of this gene may be related to the absence of the fifth finger in frogs and salamanders. | 1 | Applied and Interdisciplinary Chemistry |
The allosteric model suggests that termination occurs due to the structural change of the RNA polymerase unit after binding to or losing some of its associated proteins, making it detach from the DNA strand after the signal. This would occur after the RNA pol II unit has transcribed the poly-A signal sequence, which acts as a terminator signal.
RNA polymerase is normally capable of transcribing DNA into single-stranded mRNA efficiently. However, upon transcribing over the poly-A signals on the DNA template, a conformational shift is induced in the RNA polymerase from the proposed loss of associated proteins from its carboxyl terminal domain. This change of conformation reduces RNA polymerase's processivity making the enzyme more prone to dissociating from its DNA-RNA substrate. In this case, termination is not completed by degradation of mRNA but instead is mediated by limiting the elongation efficiency of RNA polymerase and thus increasing the likelihood that the polymerase will dissociate and end its current cycle of transcription. | 1 | Applied and Interdisciplinary Chemistry |
A chiral condensate is an example of a fermionic condensate that appears in theories of massless fermions with chiral symmetry breaking, such as the theory of quarks in Quantum Chromodynamics. | 0 | Theoretical and Fundamental Chemistry |
Eastern meadow voles are an important prey for many hawks, owls, and mammalian carnivores, and they are also taken by some snakes. Almost all species of raptors take microtine (Microtus spp.) rodents as prey. Birds not usually considered predators of mice do take voles; examples include gulls (Larus spp.), northern shrike (Larius borealis), common raven (Corvus corax), American crow (C. brachyrhynchos), great blue heron (Ardea herodias), and American bittern (Botaurus lentiginosus). In Ohio, eastern meadow voles comprised 90% of the individual prey remains in long-eared owl (Asio otus) pellets on a relict wet prairie, and in Wisconsin, eastern meadow voles comprised 95% of short-eared owl (A. flammeus) prey. Most mammalian predators take microtine prey. The American short-tailed shrew (Blarina brevicauda) is a major predator; eastern meadow voles avoid areas frequented by short-tailed shrews. Other major mammalian predators include the badger (Taxidea taxus), striped skunk (Mephitis mephitis), weasels (Mustela spp.), marten (Martes americana), domestic dog (Canis familiaris), domestic cat (Felis catus) and mountain lion. Other animals reported to have ingested voles include trout (Salmo spp.) and garter snake (Thamnophis spp.). | 1 | Applied and Interdisciplinary Chemistry |
In the relativistic limit, the momentum (speed) is large, so using the relativistic energy-momentum equation, the energy becomes essentially the momentum norm (e.g. becomes ). The rest mass can also be neglected.
So for example,
because and .
Thus, | 0 | Theoretical and Fundamental Chemistry |
Two (or more) chemically equivalent (symmetry-related) spins will have the same chemical shift, but those that have a different coupling relationship to the same coupling partner are magnetically inequivalent by the coupling criterion. This occurs in molecules bearing two (or more) chemically distinct groups of symmetry-related nuclei, with just one element of symmetry relating them. Most commonly, two chemically inequivalent pairs of hydrogen nuclei (protons) are involved, although other magnetically active nuclei will also show this phenomenon, and the spin system is often labelled an AA′BB′ system. Additional coupling partners may also be present, but it is the two A/A′ and B/B′ signals (at different chemical shifts) that are said to show magnetic inequivalence between the symmetry-related A and A′ (or B and B′) pairs at the same chemical shift. If the chemical shift difference (ν−ν) is large compared to the largest coupling constant, the spin system may be designated AA′XX′. | 0 | Theoretical and Fundamental Chemistry |
The basic building blocks of carotenoids are isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). These two isoprene isomers are used to create various compounds depending on the biological pathway used to synthesize the isomers. Plants are known to use two different pathways for IPP production: the cytosolic mevalonic acid pathway (MVA) and the plastidic methylerythritol 4-phosphate (MEP). In animals, the production of cholesterol starts by creating IPP and DMAPP using the MVA. For carotenoid production plants use MEP to generate IPP and DMAPP. The MEP pathway results in a 5:1 mixture of IPP:DMAPP. IPP and DMAPP undergo several reactions, resulting in the major carotenoid precursor, geranylgeranyl diphosphate (GGPP). GGPP can be converted into carotenes or xanthophylls by undergoing a number of different steps within the carotenoid biosynthetic pathway. | 0 | Theoretical and Fundamental Chemistry |
Falipamil is a bradycardic drug focused on decreasing the heart rate of animals. The drug focuses on treating sinuses in some animals, with the most common experiments being conducted in dogs. Falipamil is commonly administered to reduce sinus, and different dosage administrations have proven to bear different results When given in small doses, the drug is effective in reducing sinus rate, but when given in high doses, the drug increases the sinus rate as the drug increases the atrial pumping rate, thus increasing the amount of body fluid pumped through the body to the face. When falipamil is administered, the drug decreases the ventricular rate of the heart, which in turn helps reduce the sinus rate in an organism.
Falipamil has different effects on the electrophysiological structure of the heart, where different dosages result in different heart activity rates with diverse vagolytic actions. Recent studies have been carried out on dogs to determine the effectiveness of the drug in treating sinuses. When administered to a conscious dog, the sinus heart rate of the dog increases, whereas when administered to a stale dog, the animal experiences a lessened heart rate. The electrophysiological result of administering falipamil shows that the drug decreases the maximal atrial driving frequency when administered to a conscious dog, which is an effective measure in reducing sinus in a living organism. Falipamil administration also shows that the administration of the drug increases the bodys action potential exerting less bradycardic effects that are effective in reducing sinuses. Fallipamil does have different recovery times when administered to dogs involved in different activities. Intact dogs are likely to have short sinus recovery time-conscious dogs. Falipamil has a positive effect on the hearts refractory period, where the drug prolongs the atrial refractory period. | 1 | Applied and Interdisciplinary Chemistry |
In natural gas cyclic processes, a unit produces hot reducing gas, which is injected into the reactor. To ensure continuous operation of the unit converting natural gas into reducing gas, several tanks are operated in parallel and with a time lag.
The best-known of this type is HYL I and its improved variant, HYL II. This is the oldest industrial direct gas reduction process, developed in Mexico in 1957 by the Hylsa company. | 1 | Applied and Interdisciplinary Chemistry |
In a mirror furnace, material is heated by the lamps whose radiation is focused by mirrors. They are widely used for growing single crystals for scientific purposes, using the "floating zone" method. | 0 | Theoretical and Fundamental Chemistry |
Hybridization is the process of complementary base pairs binding to form a double helix. Melting is the process by which the interactions between the strands of the double helix are broken, separating the two nucleic acid strands. These bonds are weak, easily separated by gentle heating, enzymes, or mechanical force. Melting occurs preferentially at certain points in the nucleic acid. T and A rich regions are more easily melted than C and G rich regions. Some base steps (pairs) are also susceptible to DNA melting, such as T A and T G. These mechanical features are reflected by the use of sequences such as TATA at the start of many genes to assist RNA polymerase in melting the DNA for transcription.
Strand separation by gentle heating, as used in polymerase chain reaction (PCR), is simple, providing the molecules have fewer than about 10,000 base pairs (10 kilobase pairs, or 10 kbp). The intertwining of the DNA strands makes long segments difficult to separate. The cell avoids this problem by allowing its DNA-melting enzymes (helicases) to work concurrently with topoisomerases, which can chemically cleave the phosphate backbone of one of the strands so that it can swivel around the other. Helicases unwind the strands to facilitate the advance of sequence-reading enzymes such as DNA polymerase. | 0 | Theoretical and Fundamental Chemistry |
Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of ferrite (87.5 wt%) and cementite (12.5 wt%) that occurs in some steels and cast irons. During slow cooling of an iron-carbon alloy, pearlite forms by a eutectoid reaction as austenite cools below (the eutectoid temperature). Pearlite is a microstructure occurring in many common grades of steels. | 1 | Applied and Interdisciplinary Chemistry |
The freely joined chain, also called an ideal chain, follows the random walk model. Microscopically, the 3-D random walk of a polymer chain assumes the overall end-to-end distance is expressed in terms of the x, y and z directions:
In the model, is the length of a rigid segment, is the number of segments of length , is the distance between the fixed and free ends, and is the "contour length" or . Above the glass transition temperature, the polymer chain oscillates and changes over time. The probability distribution of the chain is the product of the probability distributions of the individual components, given by the following Gaussian distribution:
Therefore, the ensemble average end-to-end distance is simply the standard integral of the probability distribution over all space. Note that the movement could be backwards or forwards, so the net average will be zero. However, one can use the root mean square as a useful measure of the distance.
The Flory theory of rubber elasticity has pointed out the rubber elasticity has primarily entropic origins. By using the following basic equations for Helmholtz free energy and its discussion about entropy, the force generated from the deformation of a rubber chain from its original un-stretched conformation can be derived. The is the number of conformations of the polymer chain. Since the deformation does not involve enthalpy change, the change in free energy can just be calculated as the change in entropy. It can be observed that the force equation resembles the behavior of a spring and follows Hookes law: , where F is the force, k is the spring constant and x' is the distance. Usually, neo-Hookean model can be used on cross-linked polymers to predict their stress-strain relations:
Note that the elastic coefficient is temperature dependent. If we increase the rubber temperature, the elastic coefficient also rises. This is the reason why rubber under constant stress shrinks when its temperature increases.
We can further expand the Flory theory into a macroscopic view, where bulk rubber material is discussed. Assume the original dimension of the rubber material is , and , a deformed shape can then be expressed by applying an individual extension ratio to the length (, , ). So microscopically, the deformed polymer chain can also be expressed with the extension ratio: , , . The free energy change due to deformation can then be expressed as follows:
Assume that the rubber is cross-linked and isotropic, the random walk model gives , and are distributed according to a normal distribution. Therefore, they are equal in space, and all of them are 1/3 of the overall end-to-end distance of the chain: . Plugging in the change of free energy equation above, it is easy to get:
The free energy change per volume is just:
where is the number of strands in network, the subscript "def" means "deformation", , which is the number density per volume of polymer chains, which is the ratio between the end-to-end distance of the chain and the theoretical distance that obey random walk statistics. If we assume incompressibility, the product of extension ratios is 1, implying no change in the volume: .
In a uniaxial deformed rubber, because we assume . So the previous free energy per volume equation is:
The engineering stress (by definition) is the first derivative of the energy in terms of the extension ratio, which is equivalent to the concept of strain:
and the Young's Modulus is defined as derivative of the stress with respect to strain, which measures the stiffness of the rubber in laboratory experiments.
<math display="block">E=\frac{d(\sigma_\text{eng})}{d\lambda_z}=k_\text{B}T v_s \beta \left.\left(1+ \frac{2}{\lambda_z^3}\right)\right|_{\lambda_z=1}
= 3 k_\text{B}T v_s\beta = \frac{3\rho \beta RT}{M_s}, is the mass density of the chain, is the number average molecular weight of a network strand between crosslinks. Here, this type of analysis links the thermodynamic theory of rubber elasticity to experimentally measurable parameters. In addition, it gives in sights into the cross-linking condition of the materials. | 0 | Theoretical and Fundamental Chemistry |
His research focused on the following topics:
* crystallographic group theory in crystal chemistry (Bärnighausen trees)
* synthesis and characterization of new compounds in including rare earth metals
* structure refinements of twinned crystals | 0 | Theoretical and Fundamental Chemistry |
As PA is rapidly converted to DAG, it is very short-lived in the cell. This means that it is difficult to measure PA production and therefore to study the role of PA in the cell. However, PLD activity can be measured by the addition of primary alcohols to the cell. PLD then carries out a transphosphatidylation reaction, instead of hydrolysis, producing phosphatidyl alcohols in place of PA. The phosphatidyl alcohols are metabolic dead-ends, and can be readily extracted and measured. Thus PLD activity and PA production (if not PA itself) can be measured, and, by blocking the formation of PA, the involvement of PA in cellular processes can be inferred. | 1 | Applied and Interdisciplinary Chemistry |
Virtual karyotyping is another cost-effective, clinically available alternative to FISH panels using thousands to millions of probes on a single array to detect copy number changes, genome-wide, at unprecedented resolution. Currently, this type of analysis will only detect gains and losses of chromosomal material and will not detect balanced rearrangements, such as translocations and inversions which are hallmark aberrations seen in many types of leukemia and lymphoma. | 1 | Applied and Interdisciplinary Chemistry |
The [4+4] Photocycloaddition is a cycloaddition reaction in which two unsaturated molecules connect via four atoms from each molecule (hence "4 + 4") to create an eight-membered ring. As a photochemical reaction, it is promoted by some form of light, as opposed to a thermal process. | 0 | Theoretical and Fundamental Chemistry |
Limited precision of chemical shift measurements also puts an upper limit of about 4 on . Limited to diamagnetic systems. H NMR cannot be used with solutions of compounds in HO. | 0 | Theoretical and Fundamental Chemistry |
The metallurgical production of the Republic of Azerbaijan is considered high due to the large deposits of alunite, polymetallic ores, deposits of iron ore, etc. The metallurgy industry of Azerbaijan encompasses both ferrous and non-ferrous branches. | 1 | Applied and Interdisciplinary Chemistry |
Sulfonic acids are strong acids. They are commonly cited as being around a million times stronger than the corresponding carboxylic acid. For example, p-Toluenesulfonic acid and methanesulfonic acid have pK values of −2.8 and −1.9, respectively, while those of benzoic acid and acetic acid are 4.20 and 4.76, respectively. However, as a consequence of their strong acidity, their pK values cannot be measured directly, and values commonly quoted should be regarded as indirect estimates with significant uncertainties. For instance, various sources have reported the pK of methanesulfonic acid to be as high as −0.6 or as low as −6.5. Sulfonic acids are known to react with solid sodium chloride (salt) to form the sodium sulfonate and hydrogen chloride. This property implies an acidity within two or three orders of magnitude of that of HCl, whose pK was recently accurately determined (pK = −5.9).
Because of their polarity, sulfonic acids tend to be crystalline solids or viscous, high-boiling liquids. They are also usually colourless and nonoxidizing, which makes them suitable for use as acid catalysts in organic reactions. Their polarity, in conjunction with their high acidity, renders short-chain sulfonic acids water-soluble, while longer-chain ones exhibit detergent-like properties.
The structure of sulfonic acids is illustrated by the prototype, methanesulfonic acid. The sulfonic acid group, RSOOH features a tetrahedral sulfur centre, meaning that sulfur is at the center of four atoms: three oxygens and one carbon. The overall geometry of the sulfur centre is reminiscent of the shape of sulfuric acid. | 0 | Theoretical and Fundamental Chemistry |
O-linked glycopeptides recently have been shown to exhibit excellent CNS permeability and efficacy in multiple animal models with disease states. In addition one of the most intriguing aspects thereof is the capability of O-glycosylation to extend half life, decrease clearance, and improve PK/PD thereof the active peptide beyond increasing CNS penetration. The innate utilization of sugars as solubilizing moieties in Phase II and III metabolism (glucuronic acids) has remarkably allowed an evolutionary advantage in that mammalian enzymes are not directly evolved to degrade O glycosylated products on larger moieties.
The peculiar nature of O-linked glycopeptides is that there are numerous examples which are CNS penetrant. The fundamental basis of this effect is thought to involve "membrane hopping" or "hop diffusion". The non-brownian motion driven "hop diffusion" process is thought to occur due to discontinuity of the plasma membrane. "Hop diffusion" notably combines free diffusion and intercomparmental transitions. Recent examples notably include high permeability of met-enkephalin analogs amongst other peptides. The full mOR agonist pentapeptide DAMGO is also CNS penetrant upon introduction of glycosylation. | 0 | Theoretical and Fundamental Chemistry |
The specific study of the non-ferrous metals used in past. Gold, silver and copper were the first to be used by ancient humans. Gold and copper are both found in their native state in nature, and were thus the first to be exploited as they did not need to be smelted from their ores. They could be hammered into sheets or decorative shapes. The extraction of copper from its ores may have developed due to the attractive colouring and value of ores such as malachite. | 1 | Applied and Interdisciplinary Chemistry |
While their function has not yet been studied in great detail, it has been speculated that due to the morphological similarity of paramural bodies to the exosomes produced by mammalian cells, they may perform similar functions such as membrane vesicle trafficking between cells. Current evidence suggests that, like exosomes, paramural bodies are derived from multivesicular bodies. | 1 | Applied and Interdisciplinary Chemistry |
Work hardening is a consequence of plastic deformation, a permanent change in shape. This is distinct from elastic deformation, which is reversible. Most materials do not exhibit only one or the other, but rather a combination of the two. The following discussion mostly applies to metals, especially steels, which are well studied. Work hardening occurs most notably for ductile materials such as metals. Ductility is the ability of a material to undergo plastic deformations before fracture (for example, bending a steel rod until it finally breaks).
The tensile test is widely used to study deformation mechanisms. This is because under compression, most materials will experience trivial (lattice mismatch) and non-trivial (buckling) events before plastic deformation or fracture occur. Hence the intermediate processes that occur to the material under uniaxial compression before the incidence of plastic deformation make the compressive test fraught with difficulties.
A material generally deforms elastically under the influence of small forces; the material returns quickly to its original shape when the deforming force is removed. This phenomenon is called elastic deformation. This behavior in materials is described by Hookes Law. Materials behave elastically until the deforming force increases beyond the elastic limit, which is also known as the yield stress. At that point, the material is permanently deformed and fails to return to its original shape when the force is removed. This phenomenon is called plastic deformation. For example, if one stretches a coil spring up to a certain point, it will return to its original shape, but once it is stretched beyond the elastic limit, it will remain deformed and wont return to its original state.
Elastic deformation stretches the bonds between atoms away from their equilibrium radius of separation, without applying enough energy to break the inter-atomic bonds. Plastic deformation, on the other hand, breaks inter-atomic bonds, and therefore involves the rearrangement of atoms in a solid material. | 1 | Applied and Interdisciplinary Chemistry |
Van der Waals strain, or steric strain, occurs when atoms are forced to get closer than their Van der Waals radii allow. Specifically, Van der Waals strain is considered a form of strain where the interacting atoms are at least four bonds away from each other. The amount on steric strain in similar molecules is dependent on the size of the interacting groups; bulky tert-butyl groups take up much more space than methyl groups and often experience greater steric interactions.
The effects of steric strain in the reaction of trialkylamines and trimethylboron were studied by Nobel laureate Herbert C. Brown et al. They found that as the size of the alkyl groups on the amine were increased, the equilibrium constant decreased as well. The shift in equilibrium was attributed to steric strain between the alkyl groups of the amine and the methyl groups on boron. | 0 | Theoretical and Fundamental Chemistry |
The MEDICIS facility is located in the extension of building 179 at the CERN Meyrin site, next to the ISOLDE building. The facility was established by CERN in 2010, along with contributions from the CERN Knowledge Transfer Fund, as well as receiving a European Commission Marie-Skłodowska-Curie training grant under the title MEDICIS-PROMED. The construction of the facility started in September 2013 and was completed in 2017.
ISOLDE directs a 1.4 GeV proton beam from the Proton Synchrotron Booster (PSB) onto a thick target, the material dependent on the desired produced isotopes. Only 10% of the proton beam used in the ISOLDE facility is absorbed by the target, with the rest otherwise hitting the beam dump. MEDICIS uses these wasted protons to irradiate a second target, which produces specific isotopes, placed behind each of ISOLDE's target stations, the High Resolution Separator (HRS) and the General Purpose Separator (GPS). Alternatively, the facility uses pre-irradiated targets that are provided by external institutions. MEDICIS was one of the few facilities operating throughout the Long Shutdown 2, due to it being provided with 34 externally irradiated target materials.
Due to the high levels of radiation, the targets are transferred from the irradiation station to the radioisotope mass-separation beamline using an automated rail conveyer system (RCS). A KUKA robot is used to transport the target to the station, where the isotope of interest can be collected and radiochemically purified. This is done by heating the target up to very high temperatures, often more than 2000 °C, which causes the specified isotopes to diffuse. The isotopes are then ionised and accelerated by an ion source to be sent through a mass separator. The mass separator extracts the isotope of interest so that it can be implanted onto thin gold foils with a one-sided metallic or salt coating.
In 2019, the MEDICIS Laser Ion Source Setup At CERN (MELISSA) became fully operational, containing the individual lasers, auxiliary and control systems, and optical beam transport. The MELISSA laser laboratory has helped to successfully increase the separation efficiency and the yield of the isotopes. The laser excites only isotopes of the desired element, allowing an element-selective isotope separation for a given atomic mass from other isobars by the mass separator.
A shielded trolley is used to retrieve the samples after the radioisotopes have been collected, in order to avoid risk of contamination. Once the target is finished being used, it is sent to a hot cell in order to be safely dismantled and put in waste bins. Once collected, the samples can be sent to hospitals and research facilities with the purpose of developing patient imaging and treatment, and therapy protocols.
Additionally next to the MEDICIS facility, there is a nanolab laboratory designed for the development and assembly of nanomaterials. The nanomaterials are sealed in a glovebox, meaning there is no contact with the outside environment. It builds up on the development of the first nanostructured targets used for isotope production, and further exploits developments initiated in MEDICIS-Promed under the guidance of Prof. "Kostya" Novozelov. | 0 | Theoretical and Fundamental Chemistry |
The oldest form of mineral processing practiced since the Stone Age is hand-picking. Georgius Agricola also describes hand-picking is his book De re metallica in 1556. Sensor-based sorting is the automation and extension to hand picking. In addition to sensors that measure visible differences like color (and the further interpretation of the data regarding texture and shape), other sensors are available on industrial scale sorters that are able to measure differences invisible for the human eye (EM, XRT, NIR).
The principles of the technology and the first machinery has been developed since the 1920s (. Nevertheless, widely applied and standard technology it is only in the industrial minerals and gemstone segments. Mining is benefiting from the step change developments in sensing and computing technologies and from machine development in the recycling and food processing industries.
In 2002, Cutmore and Eberhard stated that the relatively small installed base of sensor-based sorters in mining is more a result of insufficient industry interest than any technical barriers to their effective use
Nowadays sensor-based sorting is beginning to reveal its potential in various applications in basically all segments of mineral production (industrial minerals, gemstones, base-metals, precious metals, ferrous metals, fuel). Precondition is physical liberation in coarse size ranges (~) to make physical separation possible. Either the product fraction, but more often the waste fraction needs to be liberated. If liberation is present, there is good potential that one of available detection technologies on today's sensor-based sorters can positively or negatively identify one of the two desired fractions. | 0 | Theoretical and Fundamental Chemistry |
Certain methyl groups can be deprotonated. For example, the acidity of the methyl groups in acetone () is about 10 times more acidic than methane. The resulting carbanions are key intermediates in many reactions in organic synthesis and biosynthesis. Fatty acids are produced in this way. | 0 | Theoretical and Fundamental Chemistry |
Hormonal effects are dependent on where they are released, as they can be released in different manners. Not all hormones are released from a cell and into the blood until it binds to a receptor on a target. The major types of hormone signaling are: | 1 | Applied and Interdisciplinary Chemistry |
The Society of PEth Research published a harmonization document (2022 Consensus of Basel) for the interpretation of phosphatidylethanol concentrations in the clinical and forensic setting. This consensus represents the first internationally established harmonization document on PEth and was created by an assembly of the world's leading experts in phosphatidylethanol research. The consensus defines the target measurand (PEth 16:0/18:1 in whole blood), cutoff concentrations (20 ng/mL and 200 ng/mL), and minimal requirements for the applied analytical method (accuracy and precision within 15%). | 1 | Applied and Interdisciplinary Chemistry |
Once radiative capture can no longer proceed on a given nucleus, either from photodisintegration or the drip lines, further nuclear processing to higher mass must either bypass this nucleus by undergoing a reaction with a heavier nucleus such as He, or more often wait for the beta decay. Nuclear species where a significant fraction of the mass builds up during a particular nucleosynthesis episode are considered nuclear waiting points, since further processing by fast radiative captures is delayed.
As has been emphasized, the beta decays are the slowest processes occurring in explosive nucleosynthesis. From the nuclear physics side, explosive nucleosynthesis time scales are set simply by summing the beta decay half-lives involved, since the time scale for other nuclear processes is negligible in comparison, although practically speaking this time scale is typically dominated by the sum of a handful of waiting point nuclear half lives. | 0 | Theoretical and Fundamental Chemistry |
The chemical processing and synthesis of high-performance technological components for the private, industrial, and military sectors requires the use of high-purity ceramics (oxide ceramics, such as aluminium oxide or copper(II) oxide), polymers, glass-ceramics, and composite materials, as metal carbides (SiC), nitrides (Aluminum nitrides, Silicon nitride), metals (Al, Cu), non-metals (graphite, carbon nanotubes), and layered (Al + aluminium carbonate, Cu + C). In condensed bodies formed from fine powders, the irregular particle sizes and shapes in a typical powder often lead to non-uniform packing morphologies that result in packing density variations in the powder compact.
Uncontrolled agglomeration of powders due to attractive van der Waals forces can also give rise to microstructural heterogeneity. Differential stresses that develop as a result of non-uniform drying shrinkage are directly related to the rate at which the solvent can be removed, and thus highly dependent upon the distribution of porosity. Such stresses have been associated with a plastic-to-brittle transition in consolidated bodies, and can yield to crack propagation in the unfired body if not relieved.
In addition, any fluctuations in packing density in the compact as it is prepared for the kiln are often amplified during the sintering process, yielding inhomogeneous densification. Some pores and other structural defects associated with density variations have been shown to play a detrimental role in the sintering process by growing and thus limiting end-point densities. Differential stresses arising from inhomogeneous densification have also been shown to result in the propagation of internal cracks, thus becoming the strength-controlling flaws.
Inert gas evaporation and inert gas deposition are free many of these defects due to the distillation (cf. purification) nature of the process and having enough time to form single crystal particles, however even their non-aggreated deposits have lognormal size distribution, which is typical with nanoparticles. The reason why modern gas evaporation techniques can produce a relatively narrow size distribution is that aggregation can be avoided. However, even in this case, random residence times in the growth zone, due to the combination of drift and diffusion, result in a size distribution appearing lognormal.
It would, therefore, appear desirable to process a material in such a way that it is physically uniform with regard to the distribution of components and porosity, rather than using particle size distributions that will maximize the green density. The containment of a uniformly dispersed assembly of strongly interacting particles in suspension requires total control over interparticle forces. Monodisperse nanoparticles and colloids provide this potential. | 0 | Theoretical and Fundamental Chemistry |
Differential refractometers are often used for the analysis of polymer samples in size exclusion chromatography. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, ion association is a chemical reaction whereby ions of opposite electric charge come together in solution to form a distinct chemical entity. Ion associates are classified, according to the number of ions that associate with each other, as ion pairs, ion triplets, etc. Ion pairs are also classified according to the nature of the interaction as contact, solvent-shared or solvent-separated. The most important factor to determine the extent of ion association is the dielectric constant of the solvent. Ion associates have been characterized by means of vibrational spectroscopy, as introduced by Niels Bjerrum, and dielectric-loss spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
The technique of selecting only one embryo to transfer to the woman is called elective-single embryo transfer (e-SET) or, when embryos are at the blastocyst stage, it can also be called elective single blastocyst transfer (eSBT). It significantly lowers the risk of multiple pregnancies, compared with e.g. Double Embryo Transfer (DET) or double blastocyst transfer (2BT), with a twinning rate of approximately 3.5% in sET compared with approximately 38% in DET, or 2% in eSBT compared with approximately 25% in 2BT. At the same time, pregnancy rates is not significantly less with eSBT than with 2BT. That is, the cumulative live birth rate associated with single fresh embryo transfer followed by a single frozen and thawed embryo transfer is comparable with that after one cycle of double fresh embryo transfer. Furthermore, SET has better outcomes in terms of mean gestational age at delivery, mode of delivery, birthweight, and risk of neonatal intensive care unit necessity than DET. e-SET of embryos at the cleavage stage reduces the likelihood of live birth by 38% and multiple birth by 94%. Evidence from randomized, controlled trials suggests that increasing the number of e-SET attempts (fresh and/or frozen) results in a cumulative live birth rate similar to that of DET.
The usage of single embryo transfer is highest in Sweden (69.4%), but as low as 2.8% in the USA. Access to public funding for ART, availability of good cryopreservation facilities, effective education about the risks of multiple pregnancy, and legislation appear to be the most important factors for regional usage of single embryo transfer. Also, personal choice plays a significant role as many subfertile couples have a strong preference for twins. | 1 | Applied and Interdisciplinary Chemistry |
Check dams are made of a variety of materials. Because they are typically used as temporary structures, they are often made of cheap and accessible materials such as rocks, gravel, logs, hay bales, and sandbags. Of these, logs and rock check dams are usually permanent or semi-permanent, and sandbag check dams are built primarily for temporary purposes. Also, there are check dams that are constructed with rockfill or wooden boards. These dams are usually implemented only in small, open channels that drain or less; and usually do not exceed high. Woven wire can be used to construct check dams in order to hold fine material in a gully. It is typically used in environments where the gully has a moderate slope (less than 10%), small drainage area, and in regions where flood flows do not typically carry large rocks or boulders. In nearly all instances, erosion control blankets, which are biodegradable open-weave blankets, are used in conjunction with check dams. These blankets help encourage vegetation growth on the slopes, shorelines and ditch bottoms. | 1 | Applied and Interdisciplinary Chemistry |
Extrusion bioprinting includes the consistent statement of a specific printing fabric and cell line from an extruder, a sort of portable print head. This tends to be a more controlled and gentler handle for fabric or cell statement, and permits for more noteworthy cell densities to be utilized within the development of 3D tissue or organ structures. In any case, such benefits are set back by the slower printing speeds involved by this procedure. Extrusion bioprinting is frequently coupled with UV light, which photopolymerizes the printed fabric to create a more steady, coordinated construct. | 1 | Applied and Interdisciplinary Chemistry |
After attending the Lycée Charlemagne and Lycée Lavoisier, Urbain studied at the École supérieure de physique et de chimie industrielles de la ville de Paris (ESPCI ParisTech). He graduated as the top student in the schools ninth graduating class, in 1894. At that time he also earned his licence ès sciences physique et chimie' at the Sorbonne.
Urbain served in teaching positions at the Préparateur at the École de Physique et Chimie Industrielle (1894-1895), in Charles Friedels organic chemistry laboratory (1832-1899), in the Faculté des Science P.C.N. (1895-1898), and at the École Alsacienne (1897-1899).
He completed a thesis on Recherches sur la Séparation des Terres Rares (Research into the Separation of Rare Earth Elements) in 1899. | 1 | Applied and Interdisciplinary Chemistry |
Rates of recycling and methods of waste collection vary substantially across the United States because laws are written on the state or local level and large municipalities often have their own unique systems. Many cities do curbside recycling, meaning they collect household recyclable waste on a weekly or bi-weekly basis that residents set out in special containers in front of their homes and transported to a materials recovery facility. This is typically single-stream recycling, which creates an impure product and partly explains why, as of 2019, the US has a recycling rate of around 33% versus 90% in some European countries. European countries have requirements for minimum recycled glass content, and more widespread deposit-return systems that provide more uniform material streams. The lower population density and long distances in much of the United States, and the cost of shipping heavy glass also mean that recycling is not inherently economical in places where there are no nearby buyers.
Apartment dwellers usually use shared containers that may be collected by the city or by private recycling companies which can have their own recycling rules. In some cases, glass is specifically separated into its own container because broken glass is a hazard to the people who later manually sort the co-mingled recyclables. Sorted recyclables are later sold to companies to be used in the manufacture of new products.
In 1971, the state of Oregon passed a law requiring buyers of carbonated beverages (such as beer and soda) to pay five cents per container (increased to ten cents in April 2017) as a deposit which would be refunded to anyone who returned the container for recycling. This law has since been copied in nine other states including New York and California. The abbreviations of states with deposit laws are printed on all qualifying bottles and cans. In states with these container deposit laws, most supermarkets automate the deposit refund process by providing machines which will count containers as they are inserted and then print credit vouchers that can be redeemed at the store for the number of containers returned. Small glass bottles (mostly beer) are broken, one-by-one, inside these deposit refund machines as the bottles are inserted. A large, wheeled hopper (very roughly 1.5 m by 1.5 m by 0.5 m) inside the machine collects the broken glass until it can be emptied by an employee. Nationwide bottle refunds recover 80% of glass containers that require a deposit.
Major companies in the space include Strategic Materials, which purchases post-consumer glass for 47 facilities across the country. Strategic Materials has worked to correct misconceptions about glass recycling. Glass manufacturers such as Owens-Illinois ultimately include recycled glass in their product. The Glass Recycling Coalition is a group of companies and stakeholders working to improve glass recycling. | 0 | Theoretical and Fundamental Chemistry |
Glass collection points, known as bottle banks are very common near shopping centres, at civic amenity sites and in local neighborhoods in the United Kingdom. The first bottle bank was introduced by Stanley Race CBE, then president of the Glass Manufacturers' Federation and Ron England in Barnsley on 6 June 1977. Development work was done by the DoE at Warren Spring Laboratory, Stevenage, (now AERA at Harwell) and Nazeing Glass Works, Broxbourne to prove if a usable glass product could be made from over 90% recycled glass. It was found necessary to use magnets to remove unwanted metal closures in the mixture.
Bottle banks commonly stand beside collection points for other recyclable waste like paper, metals and plastics. Local, municipal waste collectors usually have one central point for all types of waste in which large glass containers are located.
In 2007 there were over 50,000 bottle banks in the United Kingdom, and 752,000 tons of glass was being recycled annually. | 0 | Theoretical and Fundamental Chemistry |
Beta oxidation removes 2 carbons at a time, so in the oxidation of an 18 carbon fatty acid such as Stearic Acid 8 cycles will need to occur to completely break down Acyl-CoA. This will produce 9 Acetyl-CoA that have 2 carbons each, 8 FADH2, and 8 NADH. | 1 | Applied and Interdisciplinary Chemistry |
On September 5, 2019, the United States Food and Drug Administration (US FDA) announced that 10 out of 18, or 56% of the samples of vape liquids sent in by states, linked to recent vaping related lung disease outbreak in the United States, tested positive for vitamin E acetate which had been used as a thickening agent by illicit THC vape cartridge manufacturers. On November 8, 2019, the Centers for Disease Control and Prevention (CDC) identified vitamin E acetate as a very strong culprit of concern in the vaping-related illnesses, but has not ruled out other chemicals or toxicants as possible causes. The CDC's findings were based on fluid samples from the lungs of 29 patients with vaping-associated pulmonary injury, which provided direct evidence of vitamin E acetate at the primary site of injury in all the 29 lung fluid samples tested. Research suggests when vitamin E acetate is inhaled, it may interfere with normal lung functioning. "Vitamin E oil might be in 60-70% of street carts, insiders say." | 0 | Theoretical and Fundamental Chemistry |
For binary mixtures of two chemically independent components, so that . In addition to temperature and pressure, the other degree of freedom is the composition of each phase, often expressed as mole fraction or mass fraction of one component.
As an example, consider the system of two completely miscible liquids such as toluene and benzene, in equilibrium with their vapours. This system may be described by a boiling-point diagram which shows the composition (mole fraction) of the two phases in equilibrium as functions of temperature (at a fixed pressure).
Four thermodynamic variables which may describe the system include temperature (T), pressure (p), mole fraction of component 1 (toluene) in the liquid phase (x), and mole fraction of component 1 in the vapour phase (x). However, since two phases are present () in equilibrium, only two of these variables can be independent (). This is because the four variables are constrained by two relations: the equality of the chemical potentials of liquid toluene and toluene vapour, and the corresponding equality for benzene.
For given T and p, there will be two phases at equilibrium when the overall composition of the system (system point) lies in between the two curves. A horizontal line (isotherm or tie line) can be drawn through any such system point, and intersects the curve for each phase at its equilibrium composition. The quantity of each phase is given by the lever rule (expressed in the variable corresponding to the x-axis, here mole fraction).
For the analysis of fractional distillation, the two independent variables are instead considered to be liquid-phase composition (x) and pressure. In that case the phase rule implies that the equilibrium temperature (boiling point) and vapour-phase composition are determined.
Liquid–vapour phase diagrams for other systems may have azeotropes (maxima or minima) in the composition curves, but the application of the phase rule is unchanged. The only difference is that the compositions of the two phases are equal exactly at the azeotropic composition. | 0 | Theoretical and Fundamental Chemistry |
(+)-Discodermolide is a highly potent antiproliferative agent. (+)-Discodermolide treated murine Do11.10T hybridoma cells could not proceed normal cell cycling. In untreated controls, 68% of cells were found at G1 phase, and 31% were found at S phase, and less than 1% was found at the G2/M phase. However, after 3 hours (+)-discodermolide treatment, 52% were found at G1 phase, 40% at S phase, and 58% at G2 and M phase. This result indicated that (+)-discodermolide blocks the cell cycle at G2 and M phase. This inhibition effect was also found to be reversible. Cells resume normal cycling within 48 hours after removal of (+)-discodermolide from the cell culture medium.
(+)-Discodermolide arrests cell cycle via binding and stabilization of the microtubule network. Hyper-stabilization of the mitotic spindle causes cell cycle arresting at G2 and M phase and eventually leads to cell death by apoptosis. At 10µM concentration, (+)-discodermolide is able to promote microtubules assembly without microtubule-associated proteins and GTP. With microtubule-associated protein and GTP presented, 10µM (+)-discodermolide is able to initiate tubulin polymerization at 0 °C. | 0 | Theoretical and Fundamental Chemistry |
Biosolarization is an alternative technology to soil fumigation used in agriculture. It is closely related to biofumigation and soil solarization, or the use of solar power to control nematodes, bacteria, fungi and other pests that damage crops. In solarization, the soil is mulched and covered with a tarp to trap solar radiation and heat the soil to a temperature that kills pests. Biosolarization adds the use of organic amendments or compost to the soil before it is covered with plastic, which speeds up the solarization process by decreasing the soil treatment time through increased microbial activity. Research conducted in Spain on the use of biosolarization in strawberry fruit production has shown it to be a sustainable and cost effective option. The practice of biosolarization is being used among small agricultural operations in California. Biosolarization is a growing practice in response to the need for methods for organic soil solarization. The option for more widespread use of biosolarization is being studied by researchers at the [https://aghealth.ucdavis.edu/current-research-projects Western Center for Agricultural Health and Safety at the University of California at Davis] in order to validate the effectiveness of biosolarization in commercial agriculture in California, where it has the potential to greatly reduce the use of conventional fumigants. Biosolarization can also use as organic waste management practice. Recent studies showed the potential of food industrial residues as soil amendments that can improve the efficiency of biosolarization. | 1 | Applied and Interdisciplinary Chemistry |
The mechanism of a glycosynthase is similar to the hydrolysis reaction of retaining glycosidases except no covalent-enzyme intermediate is formed. Mutation of the active site nucleophile to a non-nucleophilic amino acid prevents the formation of a covalent intermediate. An activated glycosyl donor with a good anomeric-leaving group (often a fluorine) is required. The leaving group is displaced by an alcohol of the acceptor sugar aided by the active site general base amino acid of the enzyme. | 0 | Theoretical and Fundamental Chemistry |
Vflo is a commercially available, physics-based distributed hydrologic model generated by [http://www.vieuxinc.com Vieux & Associates, Inc.] Vflo uses radar rainfall data for hydrologic input to simulate distributed runoff. Vflo employs GIS maps for parameterization via a desktop interface. The model is suited for distributed hydrologic forecasting in post-analysis and in continuous operations. Vflo output is in the form of hydrographs at selected drainage network grids, as well as distributed runoff maps covering the watershed. Model applications include civil infrastructure operations and maintenance, stormwater prediction and emergency management, continuous and short-term surface water runoff, recharge estimation, soil moisture monitoring, land use planning, water quality monitoring, and water resources management. | 1 | Applied and Interdisciplinary Chemistry |
The basis of the Falkner-Skan approach are the Prandtl boundary layer equations. Ludwig Prandtl simplified the equations for fluid flowing along a wall (wedge) by dividing the flow into two areas: one close to the wall dominated by viscosity, and one outside this near-wall boundary layer region where viscosity can be neglected without significant effects on the solution. This means that about half of the terms in the Navier-Stokes equations are negligible in near-wall boundary layer flows (except in a small region near the leading edge of the plate). This reduced set of equations are known as the Prandtl boundary layer equations. For steady incompressible flow with constant viscosity and density, these read:
Mass Continuity:
-Momentum:
-Momentum:
Here the coordinate system is chosen with pointing parallel to the plate in the direction of the flow and the coordinate pointing towards the free stream, and are the and velocity components, is the pressure, is the density and is the kinematic viscosity.
A number of similarity solutions to these equations have been found for various types of flow. Falkner and Skan developed the similarity solution for the case of laminar flow along a wedge in 1930. The term similarity refers to the property that the velocity profiles at different positions in the flow look similar apart from scaling factors in the boundary layer thickness and a characteristic boundary layer velocity. These scaling factors reduce the partial differential equations to a set of relatively easily solved set of ordinary differential equations. | 1 | Applied and Interdisciplinary Chemistry |
Acylsilanes are starting compounds in the Brook rearrangement with vinyl lithium compounds to silyl enol ethers.
Acyl silanes and aryl bromides are coupling partners in Pd-catalyzed cross coupling reactions: | 0 | Theoretical and Fundamental Chemistry |
The first plastid is highly accepted within the scientific community to be derived from the engulfment of cyanobacteria ancestor into a eukaryotic organism. Evidence supporting this belief is found in many morphological similarities such as the presence of a two plasma membranes. It is thought that the first membrane belonged to the cyanobacteria ancestor. During phagocytosis, a vesicle engulfs a molecule with its plasma membrane to allow safe import. When the cyanobacteria became engulfed, the bacterium avoided digestion and led to the double membrane found in primary plastids. However, in order to live in symbiosis, the eukaryotic cell that engulfed the cyanobacterium must now provide proteins and metabolites to maintain the functions of the bacteria in exchange for energy. Thus, an engulfed cyanobacterium must give up some of its genetic material to allow for endosymbiotic gene transfer to the eukaryote, a phenomenon that is thought to be extremely rare due to the "learned nature" of the interactions that must occur between the cells to allow for processes such as; gene transfer, protein localization, excretion of highly reactive metabolites, and DNA repair. This would mean, a reduction in genome size, for the cyanobacteria, but also an increase in cytobacterial genes within the eukaryotic genome. The genus of Synechocystis sp., strain PCC6803 is a unicellular fresh water cyanobacteria that encodes 3725 genes, and a 3.9 Mb sized genome. However, most plastids rarely exceed 200 protein coding genes. A recent study sequenced the genome of a cyanobacterium that was living extracellularly in endosymbiosis with the water-fern Azolla filiculoides. Endosymbiosis was supported by the fact that the cyanobacterium was unable to grow autonomously, and the observance of the cyanobacterium being vertically transferred between succeeding generations. After cyanobacterium genome analysis, the researchers found that over 30% of the genome was made up of pseudogenes. In addition, roughly 600 transposable elements were found within the genome. The pseudogenes were found in genes such as dnaA, DNA repair genes, glycolysis and nutrient uptake genes. dnaA is essential to initiation of DNA replication in prokaryotic organisms, thus Azolla filiculoides is thought to provide nutrients, and transcriptional factors for DNA replication in exchange for fixed nitrogen that is not readily available in water. Although the cyanobacterium had not been completely engulfed in the eukaryotic organism, the relationship is thought to demonstrate the precursor to endosymbiotic primary plastids. | 0 | Theoretical and Fundamental Chemistry |
VIM involves placing a core-less induction furnace into a vacuum chamber. The melting and casting operations are carried out at low pressures to control the entire alloy chemistry process. | 1 | Applied and Interdisciplinary Chemistry |
Steel casing pipe generally has no specific specifications, other than the need for the material to be extremely straight and round. In some areas A.S.T.M. specifications may be required by project engineers. The specification most commonly called for is A.S.T.M. 139 Grade B. This specification gives parameters for minimum yield and tensile strength of the steel pipe being used for casing, and tolerances of straightness and concentricity.
Steel casing pipe is often specified as ASTM A-252 which is a structural grade material that does not require hydrostatic testing and the inspection requirements are not stringent and it usually costs less than other grades such as A-53, A-139 or API 5L. Used natural gas line pipe is also used as casing on many projects because it is often reclaimed in very good condition and can offer a significant cost savings when compared to new steel pipe. Used pipe is most likely to not have any testing data associated with it and is generally used when the only required specification is a given diameter and wall thickness of steel casing pipe. | 1 | Applied and Interdisciplinary Chemistry |
*1996 – A. R. Day Award (ACS Philadelphia Section award)
*1997 – Chemical Society of Japan Award
*1998 – Herbert N. McCoy Award
*1998 – American Chemical Society Award for Organometallic Chemistry
*1998–2000 – Alexander von Humboldt Senior Researcher Award
*2003 – Sigma Xi Award, Purdue University
*2007 – Yamada–Koga Prize
*2007 – Gold Medal of Charles University, Prague, Czech Republic
*2010 – Nobel Prize in Chemistry
*2010 – ACS Award for Creative Work in Synthetic Organic Chemistry
*2015 – Fray International Sustainability Award, SIPS 2015 | 0 | Theoretical and Fundamental Chemistry |
After events such as earthquakes and tsunamis, there is an immediate response by the aid agencies as relief operations get underway to try and restore basic infrastructure and provide the basic fundamental items that are necessary for survival and subsequent recovery. The threat of disease increases hugely due to the large numbers of people living close together, often in squalid conditions, and without proper sanitation.
After a natural disaster, as far as water quality testing is concerned, there are widespread views on the best course of action to take and a variety of methods can be employed. The key basic water quality parameters that need to be addressed in an emergency are bacteriological indicators of fecal contamination, free chlorine residual, pH, turbidity and possibly conductivity/total dissolved solids. There are many decontamination methods.
After major natural disasters, a considerable length of time might pass before water quality returns to pre-disaster levels. For example, following the 2004 Indian Ocean tsunami the Colombo-based International Water Management Institute (IWMI) monitored the effects of saltwater and concluded that the wells recovered to pre-tsunami drinking water quality one and a half years after the event. IWMI developed protocols for cleaning wells contaminated by saltwater; these were subsequently officially endorsed by the World Health Organization as part of its series of Emergency Guidelines. | 0 | Theoretical and Fundamental Chemistry |
The electron transport chain carries both protons and electrons, passing electrons from donors to acceptors, and transporting protons across a membrane. These processes use both soluble and protein-bound transfer molecules. In mitochondria, electrons are transferred within the intermembrane space by the water-soluble electron transfer protein cytochrome c. This carries only electrons, and these are transferred by the reduction and oxidation of an iron atom that the protein holds within a heme group in its structure. Cytochrome c is also found in some bacteria, where it is located within the periplasmic space.
Within the inner mitochondrial membrane, the lipid-soluble electron carrier coenzyme Q10 (Q) carries both electrons and protons by a redox cycle. This small benzoquinone molecule is very hydrophobic, so it diffuses freely within the membrane. When Q accepts two electrons and two protons, it becomes reduced to the ubiquinol form (QH); when QH releases two electrons and two protons, it becomes oxidized back to the ubiquinone (Q) form. As a result, if two enzymes are arranged so that Q is reduced on one side of the membrane and QH oxidized on the other, ubiquinone will couple these reactions and shuttle protons across the membrane. Some bacterial electron transport chains use different quinones, such as menaquinone, in addition to ubiquinone.
Within proteins, electrons are transferred between flavin cofactors, iron–sulfur clusters and cytochromes. There are several types of iron–sulfur cluster. The simplest kind found in the electron transfer chain consists of two iron atoms joined by two atoms of inorganic sulfur; these are called [2Fe–2S] clusters. The second kind, called [4Fe–4S], contains a cube of four iron atoms and four sulfur atoms. Each iron atom in these clusters is coordinated by an additional amino acid, usually by the sulfur atom of cysteine. Metal ion cofactors undergo redox reactions without binding or releasing protons, so in the electron transport chain they serve solely to transport electrons through proteins. Electrons move quite long distances through proteins by hopping along chains of these cofactors. This occurs by quantum tunnelling, which is rapid over distances of less than 1.4 m. | 1 | Applied and Interdisciplinary Chemistry |
The Cephalodiscidae mitochondrial code (translation table 33) is a genetic code used by the mitochondrial genome of Cephalodiscidae (Pterobranchia). The Pterobranchia are one of the two groups in the Hemichordata which together with the Echinodermata and Chordata form the major clades of deuterostomes.
Code 33 is very similar to the mitochondrial code 24 for the Pterobranchia, which also belong to the Hemichordata, except that it uses UAA for tyrosine rather than as a stop codon.
This code shares with many other mitochondrial codes the reassignment of the UGA STOP to tryptophan, and AGG and AGA to an amino acid other than arginine. However, the assignment of AGG to lysine in pterobranchian mitogenomes is not found elsewhere in deuterostome mitochondria but it occurs in some taxa of Arthropoda. | 1 | Applied and Interdisciplinary Chemistry |
The idea of nanothermodynamics was initially proposed by T. L. Hill in 1960, theorizing the differences between differential and integral forms of properties due to small sizes. The size, shape, and environment of a nanoparticle affect the power law, or its proportionality, between nano and macroscopic properties. Transitioning from macro to nano changes the proportionality from exponential to power. Therefore, nanothermodynamics and the theory of statistical mechanics are related in concept. | 0 | Theoretical and Fundamental Chemistry |
A Pythagorean cup (also known as a Pythagoras cup, Greedy Cup, Cup of Justice or Tantalus cup) is a practical joke device in a form of a drinking cup, credited to Pythagoras of Samos. When it is filled beyond a certain point, a siphoning effect causes the cup to drain its entire contents through the base. The cup has been used to make statements about greed. | 1 | Applied and Interdisciplinary Chemistry |
Percoll does not notably diffuse over time, resulting in the formation of very stable gradients. Therefore, both discontinuous and continuous Percoll density gradients can be prepared weeks in advance, allowing great reproducibility & ease of use. | 1 | Applied and Interdisciplinary Chemistry |
Major NMR instrument makers include Thermo Fisher Scientific, Magritek, Oxford Instruments, Bruker, Spinlock SRL, General Electric, JEOL, Kimble Chase, Philips, Siemens AG, and formerly Agilent Technologies (who acquired Varian, Inc.). | 0 | Theoretical and Fundamental Chemistry |
The DNA sequence of the fd genome has 6408 nucleotide comprising 9 genes, but the genome has 11 open reading frames producing 11 proteins, since two genes, gene 2 and gene 1, have internal in-frame translation starts, generating two additional proteins, p10 and p11. The genome also contains a short non-coding intergenic sequence. M13 and f1 sequences are slightly different from fd. They both have only 6407 nucleotides; f1 differs from fd in 180 positions (only 10 of these changes are reflected in amino-acid changes in gene products) and M13 has only 59 nucleotide differences from f1. For many purposes the phages in the Ff group can be considered as interchangeable.
Five gene products are part of the virion: the major coat protein (p8) and the minor proteins capping the two ends, p3 and p6 at one end, and p7 and p9 at the other end. Three gene products (p2, p5, and p10) are cytoplasmic proteins needed for DNA synthesis and the rest are membrane proteins involved in assembly of the virion.
The gene encoding p1 has been used as a conserved marker gene, along with three other features specific for inovirus genomes, in an automatic machine-learning approach to identify over 10000 inovirus-like sequences from microbial genomes. | 1 | Applied and Interdisciplinary Chemistry |
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