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As the name contains the prefix thio-, these compounds contain sulfur. Examples include sinigrin, found in black mustard, and sinalbin, found in white mustard. | 0 | Theoretical and Fundamental Chemistry |
The use of materials began in the Stone Age. Typically, materials such as bone, fibers, feathers, shells, animal skin, and clay were used for weapons, tools, jewelry, and shelter. The earliest tools were in the paleolithic age, called Oldowan. These were tools created from chipped rocks that would be used for scavenging purpose. As history carried on into the Mesolithic age, tools became more complex and symmetrical in design with sharper edges. Moving into the Neolithic age, agriculture began to develop as new ways to form tools for farming were discovered. Nearing the end of the Stone Age, humans began using copper, gold, and silver as a material. Due to these metals' softness, the general use was for ceremonial purposes and to create ornaments or decorations and did not replace other materials for use in tools. The simplicity of the tools used reflected on the simple understanding of the human species of the time. | 1 | Applied and Interdisciplinary Chemistry |
According to popular legend, Galvani discovered the effects of electricity on muscle tissue when investigating an unrelated phenomenon which required skinned frogs in the 1780s and 1790s. His assistant is claimed to have accidentally touched a scalpel to the sciatic nerve of the frog and this resulted in a spark and animation of its legs. This was building on the theories of Giovanni Battista Beccaria, Felice Fontana, Leopoldo Marco Antonio Caldani, and . Galvani was investigating the effects of distant atmospheric electricity (lightning) on prepared frog legs when he discovered the legs convulsed not only when lightning struck but also when he pressed the brass hooks attached to the frogs spinal cord to the iron railing they were suspended from. In his laboratory, Galvani later discovered that he could replicate this phenomenon by touching metal electrodes of brass connected to the frogs spinal cord to an iron plate. He concluded that this was proof of "animal electricity," the electric power which animated living things. | 0 | Theoretical and Fundamental Chemistry |
Speisses are alloys of heavy metals like iron, cobalt, nickel and copper with arsenic, antimony and, occasionally, tin. The latter elements lower the melting point to around 1000 °C. Speisses commonly occur in lead smelting operations and copper smelting operations.
Speisses are only partially miscible with mattes, and if there is enough arsenic or antimony in the copper feed to a matte smelting furnace, a separate speiss melt can form. Speisses show high affinities for platinum group metals and gold. The mass concentration of platinum group metals in the speiss phase is about 1000 times that of the concentration in the matte phase, while the ratio for gold is about 100 times.
Speisses are also immiscible in liquid lead and flow out of lead blast furnaces as a separate phase. | 1 | Applied and Interdisciplinary Chemistry |
Super-enhancers have been most commonly identified by locating genomic regions that are highly enriched in ChIP-Seq signal. ChIP-Seq experiments targeting master transcription factors and co-factors like Mediator or BRD4 have been used, but the most frequently used is H3K27ac-marked nucleosomes. The program “ROSE” (Rank Ordering of Super-Enhancers) is commonly used to identify super-enhancers from ChIP-Seq data. This program stitches together previously identified enhancer regions and ranks these stitched enhancers by their ChIP-Seq signal. The stitching distance selected to combine multiple individual enhancers into larger domains can vary. Because some markers of enhancer activity also are enriched in promoters, regions within promoters of genes can be disregarded. ROSE separates super-enhancers from typical enhancers by their exceptional enrichment in a mark of enhancer activity. Homer is another tool that can identify super-enhancers. | 1 | Applied and Interdisciplinary Chemistry |
Electrometallurgy is a method in metallurgy that uses electrical energy to produce metals by electrolysis. It is usually the last stage in metal production and is therefore preceded by pyrometallurgical or hydrometallurgical operations. The electrolysis can be done on a molten metal oxide (smelt electrolysis) which is used for example to produce aluminium from aluminium oxide via the Hall-Hérault process. Electrolysis can be used as a final refining stage in pyrometallurgical metal production (electrorefining) and it is also used for reduction of a metal from an aqueous metal salt solution produced by hydrometallurgy (electrowinning). | 1 | Applied and Interdisciplinary Chemistry |
It is possible to formulate equations describing three conservation laws for quantities that are useful in open-channel flow: mass, momentum, and energy. The governing equations result from considering the dynamics of the flow velocity vector field with components . In Cartesian coordinates, these components correspond to the flow velocity in the x, y, and z axes respectively.
To simplify the final form of the equations, it is acceptable to make several assumptions:
# The flow is incompressible (this is not a good assumption for rapidly-varied flow)
# The Reynolds number is sufficiently large such that viscous diffusion can be neglected
# The flow is one-dimensional across the x-axis | 1 | Applied and Interdisciplinary Chemistry |
An isocyanide (also called isonitrile or carbylamine) is an organic compound with the functional group –. It is the isomer of the related nitrile (–C≡N), hence the prefix is isocyano. The organic fragment is connected to the isocyanide group through the nitrogen atom, not via the carbon. They are used as building blocks for the synthesis of other compounds. | 0 | Theoretical and Fundamental Chemistry |
MITF is phosphorylated on several serine and tyrosine residues. Serine phosphorylation is regulated by several signaling pathways including MAPK/BRAF/ERK, receptor tyrosine kinase KIT, GSK-3 and mTOR. In addition, several kinases including PI3K, AKT, SRC and P38 are also critical activators of MITF phosphorylation. In contrast, tyrosine phosphorylation is induced by the presence of the KIT oncogenic mutation D816V. This KIT pathway is dependent on SRC protein family activation signaling. The induction of serine phosphorylation by the frequently altered MAPK/BRAF pathway and the GSK-3 pathway in melanoma regulates MITF nuclear export and thereby decreasing MITF activity in the nucleus. Similarly, tyrosine phosphorylation mediated by the presence of the KIT oncogenic mutation D816V also increases the presence of MITF in the cytoplasm. | 1 | Applied and Interdisciplinary Chemistry |
Rubrocurcumin produces a red-colored solution.
Rubrocurcumin is a neutral molecule, while rosocyanine is ionic. In rubrocurcumin, one molecule of curcumin is replaced with oxalate compared to rosocyanine.
Complexes with boron such as rubrocurcumin are called 1,3,2-dioxaborines. | 0 | Theoretical and Fundamental Chemistry |
The following is a sample recipe for BBS:
*10 mM Sodium borate
*150 mM NaCl
Adjust pH to pH 8.2
The simplest way to prepare a BBS solution is to use BBS tablets. They are formulated to give a ready to use borate buffered saline solution upon dissolution in 500 ml of deionized water.
Concentration of borate and NaCl as well as the pH can vary, and the resulting solution would still be referred to as "borate buffered saline".
Borate concentration (giving buffering capacity) can vary from 10 mM to 100 mM. As BBS is used to emulate physiological conditions (as in animal or human body), the pH value is slightly alkaline, ranging from 8.0 to 9.0.
NaCl gives the isotonic (mostly used 150 mM NaCl corresponds to physiological conditions: 0.9% NaCl) salt concentration. | 1 | Applied and Interdisciplinary Chemistry |
In general there are three major categories of pH meters. Benchtop pH meters are often used in laboratories and are used to measure samples which are brought to the pH meter for analysis. Portable, or field pH meters, are handheld pH meters that are used to take the pH of a sample in a field or production site. In-line or in situ pH meters, also called pH analyzers, are used to measure pH continuously in a process, and can stand-alone, or be connected to a higher level information system for process control.
pH meters range from simple and inexpensive pen-like devices to complex and expensive laboratory instruments with computer interfaces and several inputs for indicator and temperature measurements to be entered to adjust for the variation in pH caused by temperature. The output can be digital or analog, and the devices can be battery-powered or rely on line power. Some versions use telemetry to connect the electrodes to the voltmeter display device.
Specialty meters and probes are available for use in special applications, such as harsh environments and biological microenvironments. There are also holographic pH sensors, which allow pH measurement colorimetrically, making use of the variety of pH indicators that are available. Additionally, there are commercially available pH meters based on solid state electrodes, rather than conventional glass electrodes. | 0 | Theoretical and Fundamental Chemistry |
In 1960, Bussard conceived of the Bussard ramjet, an interstellar space drive powered by hydrogen fusion using hydrogen collected with a magnetic field from the interstellar gas. Due to the presence of high-energy particles throughout space, much of the interstellar hydrogen exists in an ionized state (H II regions) that can be manipulated by magnetic or electric fields. Bussard proposed to "scoop" up ionized hydrogen and funnel it into a fusion reactor, using the exhaust from the reactor as a rocket engine.
It appears the energy gain in the reactor must be extremely high for the ramjet to work at all; any hydrogen picked up by the scoop must be sped up to the same speed as the ship in order to provide thrust, and the energy required to do so increases with the ship's speed. Hydrogen itself does not fuse very well (unlike deuterium, which is rare in the interstellar medium), and so cannot be used directly to produce energy, a fact which accounts for the billion-year scale of stellar lifetimes. This problem was solved, in principle, according to Bussard by use of the stellar CNO cycle in which carbon is used as a catalyst to burn hydrogen via the strong nuclear reaction. | 0 | Theoretical and Fundamental Chemistry |
Comex provides sorting technologies for mining industries using multi-sensory solution integrated in the same sorting units, like X-ray, hyper-spectral IR and color optical sensors and 3D cameras, which can be very effective in identifying and sorting of various mineral particles. Integration of AI models for sensor data processing is of critical importance to achieve good sorting results. | 0 | Theoretical and Fundamental Chemistry |
The MRFM concept combines the ideas of magnetic resonance imaging (MRI) and atomic force microscopy (AFM). Conventional MRI employs an inductive coil as an antenna to sense resonant nuclear or electronic spins in a magnetic field gradient. MRFM uses a cantilever tipped with a ferromagnetic (iron cobalt) particle to directly detect a modulated spin gradient force between sample spins and the tip. The magnetic particle is characterized using the technique of cantilever magnetometry. As the ferromagnetic tip moves close to the sample, the atoms' nuclear spins become attracted to it and generate a small force on the cantilever. The spins are then repeatedly flipped, causing the cantilever to gently sway back and forth in a synchronous motion. That displacement is measured with an interferometer (laser beam) to create a series of 2-D images of the sample, which are combined to generate a 3-D image. The interferometer measures resonant frequency of the cantilever. Smaller ferromagnetic particles and softer cantilevers increase the signal-to-noise ratio. Unlike the inductive coil approach, MRFM sensitivity scales favorably as device and sample dimensions are reduced.
Because the signal-to-noise ratio is inversely proportional to the sample size, Brownian motion is the primary source of noise at the scale in which MRFM is useful. Accordingly, MRFM devices are cryogenically cooled. MRFM was specifically devised to determine the structure of proteins in situ. | 0 | Theoretical and Fundamental Chemistry |
One notable example of functional selectivity occurs with the 5-HT receptor, as well as the 5-HT receptor. Serotonin, the main endogenous ligand of 5-HT receptors, is a functionally selective agonist at this receptor, activating phospholipase C (which leads to inositol triphosphate accumulation), but does not activate phospholipase A2, which would result in arachidonic acid signaling. However, the other endogenous compound dimethyltryptamine activates arachidonic acid signaling at the 5-HT receptor, as do many exogenous hallucinogens such as DOB and lysergic acid diethylamide (LSD). Notably, LSD does not activate IP signaling through this receptor to any significant extent. (Conversely, LSD, unlike serotonin, has negligible affinity for the 5-HT isoform, is unable to promote calcium release, and is, thus, functionally selective at 5-HT.) Oligomers, specifically 5-HT– heteromers, mediate this effect. This may explain why some direct 5-HT receptor agonists have psychedelic effects, whereas compounds that indirectly increase serotonin signaling at the 5-HT receptors generally do not, for example: selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), and medications using 5HT receptor agonists that do not have constitutive activity at the mGluR2 dimer, such as lisuride.
Tianeptine, an atypical antidepressant, is thought to exhibit functional selectivity at the μ-opioid receptor to mediate its antidepressant effects.
Oliceridine is a μ-opioid receptor agonist that has been described to be functionally selective towards G protein and away from β-arrestin2 pathways. However, recent reports highlight that, rather than functional selectivity or G protein bias, this agonist has low intrinsic efficacy. In vivo, it has been reported to mediate pain relief without tolerance nor gastrointestinal side effects.
The delta opioid receptor agonists SNC80 and ARM390 demonstrate functional selectivity that is thought to be due to their differing capacity to cause receptor internalization. While SNC80 causes delta opioid receptors to internalize, ARM390 causes very little receptor internalization. Functionally, that means that the effects of SNC80 (e.g. analgesia) do not occur when a subsequent dose follows the first, whereas the effects of ARM390 persist. However, tolerance to ARM390's analgesia still occurs eventually after multiple doses, though through a mechanism that does not involve receptor internalization. Interestingly, the other effects of ARM390 (e.g. decreased anxiety) persist after tolerance to its analgesic effects has occurred.
An example of functional selectivity to bias metabolism was demonstrated for an electron transfer protein cytochrome P450 reductase (POR) with binding of small molecule ligands shown to alter the protein conformation and interaction with various redox partner proteins of POR. | 1 | Applied and Interdisciplinary Chemistry |
This phase is favored in detergent-in-water solutions and has a packing ratio of less than one. The micellar population in a detergent/water mixture cannot increase without limit as the detergent to water ratio increases. In the presence of low amounts of water, lipids that would normally form micelles will form larger aggregates in the form of micellar tubules in order to satisfy the requirements of the hydrophobic effect. These aggregates can be thought of as micelles that are fused together. These tubes have the polar head groups facing out, and the hydrophobic hydrocarbon chains facing the interior. This phase is only seen under unique, specialized conditions, and most likely is not relevant for biological membranes. | 0 | Theoretical and Fundamental Chemistry |
The primary essential parts for this phase include detailing the reaction conditions in full, giving both the amount of RNA used and the total volume of the reaction, give information on the oligonucleotide used as a primer and its concentration, the concentration and type of reverse transcriptase used, and lastly the temperature and amount of time done for the reaction. It is also desirable to have the catalog numbers of reagents used and their manufacturers, the standard deviation for the Cq with and without the transcriptase being involved, and how the cDNA was stored. | 1 | Applied and Interdisciplinary Chemistry |
In fluid dynamics, the Coriolis–Stokes force is a forcing of the mean flow in a rotating fluid due to interaction of the Coriolis effect and wave-induced Stokes drift. This force acts on water independently of the wind stress.
This force is named after Gaspard-Gustave Coriolis and George Gabriel Stokes, two nineteenth-century scientists. Important initial studies into the effects of the Earth's rotation on the wave motion – and the resulting forcing effects on the mean ocean circulation – were done by , and .
The Coriolis–Stokes forcing on the mean circulation in an Eulerian reference frame was first given by :
to be added to the common Coriolis forcing Here is the mean flow velocity in an Eulerian reference frame and is the Stokes drift velocity – provided both are horizontal velocities (perpendicular to ). Further is the fluid density, is the cross product operator, where is the Coriolis parameter (with the Earths rotation angular speed and the sine of the latitude) and is the unit vector in the vertical upward direction (opposing the Earths gravity).
Since the Stokes drift velocity is in the wave propagation direction, and is in the vertical direction, the Coriolis–Stokes forcing is perpendicular to the wave propagation direction (i.e. in the direction parallel to the wave crests). In deep water the Stokes drift velocity is with the wave's phase velocity, the wavenumber, the wave amplitude and the vertical coordinate (positive in the upward direction opposing the gravitational acceleration). | 1 | Applied and Interdisciplinary Chemistry |
MOFs have been explored for electrolysis to enhance the rate and selectivity of reactions. Owing to their high surface area they can provide large number of interaction site for the reaction, conductivity of the material allows charge transfer during the electrocatalytic process. Two Cobalt based MOFs Co-BHT (Benzenehexathiol) and Co-HTTP (Hexathioltriphenylene) have been investigated for hydrogen evolution reaction (HER). In this report, overpotential values for Co-BHT and Co-HTTP are found to be 340 mV and 530 mV respectively at pH 1.3. The tafel slopes are between 149 and 189 mV dec at pH 4.2. Ultrathin sheets of Co-HAB MOF have been found to be catalytically active for oxygen evolution reaction (OER). Overpotential for this MOF was 310 mV at 10 mA cm in 1M KOH. Authors claimed that the ultrathin sheets were better than nanoparticles/thick sheets/bulk Co-HAB MOF because of favourable electrode kinetics. A 2-D conductive MOF has also been employed as an electrocatalyst for oxygen reduction reaction (ORR). Ni(HITP) MOF film on glassy carbon electrode in their study showed a potential of 820 mV at 50 μA in 0.1 M potassium hydroxide (KOH). | 0 | Theoretical and Fundamental Chemistry |
*1990, American Chemical Society Division of Analytical Chemistry J. Calvin Giddings Award for Excellence in Teaching
*2002, Electrochemical Society Henry B. Linford Award for Distinguished Teaching
*2006, W. George Pinnell Award for Outstanding Service, Indiana University Bloomington
*2007, Elected Fellow of the Electrochemical Society
*2012, Electrochemical Society Division of Organic and Biological Electrochemistry, Manuel M. Baizer Award
*2012, Elected Fellow of the American Association for the Advancement of Science
*2017, Elected Fellow of the American Chemical Society
*2020, American Chemical Society Division of Analytical Chemistry, Roland F. Hirsch Award for Distinguished Service | 0 | Theoretical and Fundamental Chemistry |
There are a number of distinct methods of holding the precursors together prior to the ultimate ring-closing reaction in a template-directed catenane synthesis. Each noncovalent approach to catenane formation results in what can be considered different families of catenanes.
Another family of catenanes are called pretzelanes or bridged [2]catenanes after their likeness to pretzels with a spacer linking the two macrocycles. In one such system one macrocycle is an electron deficient oligo Bis-bipyridinium ring and the other cycle is crown ether cyclophane based on para phenylene or naphthalene. X-ray diffraction shows that due to pi-pi interactions the aromatic group of the cyclophane is held firmly inside the pyridinium ring. A limited number of (rapidly interchanging) conformers exist for this type of compound.
In handcuff-shaped catenanes, two connected rings are threaded through the same ring. The bis-macrocycle (red) contains two phenanthroline units in a crown ether chain. The interlocking ring is self-assembled when two more phenanthroline units with alkene arms coordinate through a copper(I) complex followed by a metathesis ring closing step. | 0 | Theoretical and Fundamental Chemistry |
The theory of response reactions (RERs) was elaborated for systems in which several physico-chemical processes run simultaneously in mutual interaction, with local thermodynamic equilibrium, and in which state variables called extents of reaction are allowed, but thermodynamic equilibrium proper is not required. It is based on detailed analysis of the Hessian determinant, using either the Gibbs or the De Donder method of analysis. The theory derives the sensitivity coefficient as the sum of the contributions of individual RERs. Thus phenomena which are in contradiction to over-general statements of the Le Chatelier principle can be interpreted. With the help of RERs the equilibrium coupling was defined. RERs could be derived based either on the species, or on the stoichiometrically independent reactions of a parallel system. The set of RERs is unambiguous in a given system; and the number of them (M) is , where S denotes the number of species and C refers to the number of components. In the case of three-component systems, RERs can be visualized on a triangle diagram. | 0 | Theoretical and Fundamental Chemistry |
It is also used to prevent bacterial endocarditis and as a pain-reliever in high-risk people having dental work done, to prevent Streptococcus pneumoniae and other encapsulated bacterial infections in those without spleens, such as people with sickle-cell disease, and for both the prevention and the treatment of anthrax. The United Kingdom recommends against its use for infectious endocarditis prophylaxis. These recommendations do not appear to have changed the rates of infection for infectious endocarditis. | 0 | Theoretical and Fundamental Chemistry |
The biological treatment of wastewater in the sewage treatment plant is often accomplished using conventional activated sludge systems. These systems generally require large surface areas for treatment and biomass separation units due to the generally poor settling properties of the sludge. Aerobic granules are a type of sludge that can self-immobilize flocs and microorganisms into spherical and strong compact structures. The advantages of aerobic granular sludge are excellent settleability, high biomass retention, simultaneous nutrient removal and tolerance to toxicity. Recent studies show that aerobic granular sludge treatment could be a potentially good method to treat high strength wastewaters with nutrients, toxic substances.
The aerobic granular sludge usually is cultivated in SBR (sequencing batch reactor) and applied successfully as a wastewater treatment for high strength wastewater, toxic wastewater and domestic wastewater. Compared with conventional aerobic granular processes for COD removal, current research focuses more on simultaneous nutrient removal, particularly COD, phosphorus and nitrogen, under pressure conditions, such as high salinity or thermophilic condition.
In recent years, new technologies have been developed to improve settleability. The use of aerobic granular sludge technology is one of them. | 1 | Applied and Interdisciplinary Chemistry |
The reaction was discovered in the 1970s as part of a synthetic route to certain prostanoids. The reaction required tin tetrachloride and a stoichiometric amount of Wilkinson's catalyst:
An equal amount of a cyclopropane was formed as the result of decarbonylation.
The first catalytic application involved cyclization of 4-pentenal to cyclopentanone using (again) Wilkinson's catalyst. In this reaction the solvent was saturated with ethylene.
:CH=CHCHCHCHO → (CH)CO | 0 | Theoretical and Fundamental Chemistry |
RNA can also be transfected into cells to transiently express its coded protein, or to study RNA decay kinetics. RNA transfection is often used in primary cells that do not divide.
siRNAs can also be transfected to achieve RNA silencing (i.e. loss of RNA and protein from the targeted gene). This has become a major application in research to achieve "knock-down" of proteins of interests (e.g. Endothelin-1) with potential applications in gene therapy. Limitation of the silencing approach are the toxicity of the transfection for cells and potential "off-target" effects on the expression of other genes/proteins.
RNA can be purified from cells after lysis or synthesized from free nucleotides either chemically, or enzymatically using an RNA polymerase to transcribe a DNA template. As with DNA, RNA can be delivered to cells by a variety of means including microinjection, electroporation, and lipid-mediated transfection. If the RNA encodes a protein, transfected cells may translate the RNA into the encoded protein. If the RNA is a regulatory RNA (such as a miRNA), the RNA may cause other changes in the cell (such as RNAi-mediated knockdown).
Encapsulating the RNA molecule in lipid nanoparticles was a breakthrough for producing viable RNA vaccines, solving a number of key technical barriers in delivering the RNA molecule into the human cell.
RNA molecules shorter than about 25nt (nucleotides) largely evade detection by the innate immune system, which is triggered by longer RNA molecules. Most cells of the body express proteins of the innate immune system, and upon exposure to exogenous long RNA molecules, these proteins initiate signaling cascades that result in inflammation. This inflammation hypersensitizes the exposed cell and nearby cells to subsequent exposure. As a result, while a cell can be repeatedly transfected with short RNA with few non-specific effects, repeatedly transfecting cells with even a small amount of long RNA can cause cell death unless measures are taken to suppress or evade the innate immune system (see "Long-RNA transfection" below).
Short-RNA transfection is routinely used in biological research to knock down the expression of a protein of interest (using siRNA) or to express or block the activity of a miRNA (using short RNA that acts independently of the cells RNAi machinery, and therefore is not referred to as siRNA). While DNA-based vectors (viruses, plasmids) that encode a short RNA molecule can also be used, short-RNA transfection does not risk modification of the cells DNA, a characteristic that has led to the development of short RNA as a new class of macromolecular drugs.
Long-RNA transfection is the process of deliberately introducing RNA molecules longer than about 25nt into living cells. A distinction is made between short- and long-RNA transfection because exogenous long RNA molecules elicit an innate immune response in cells that can cause a variety of nonspecific effects including translation block, cell-cycle arrest, and apoptosis. | 1 | Applied and Interdisciplinary Chemistry |
There are several other bioprinting techniques which are less commonly used. Droplet-based bioprinting is a technique in which the bioink blend of cells and/or hydrogels are placed in droplets in precise positions. Most common amongst this approach are thermal and piezoelectric-drop-on-demand techniques. This method of bioprinting is often used experimentally with lung and ovarian cancer models. Thermal technologies use short duration signals to heat the bioink, inducing the formation of small bubbles which are ejected. Piezoelectric bioprinting has short duration current applied to a piezoelectric actuator, which induces a mechanical vibration capable of ejecting a small globule of bioink through the nozzle. A significant aspect of the study of droplet-based approaches to bioprinting is accounting for mechanical and thermal stress cells within the bioink experience near the nozzle-tip as they are extruded. | 1 | Applied and Interdisciplinary Chemistry |
UV attack by sunlight can be ameliorated or prevented by adding anti-UV polymer stabilizers, usually prior to shaping the product by injection moulding. UV stabilizers in plastics usually act by absorbing the UV radiation preferentially, and dissipating the energy as low-level heat. The chemicals used are similar to those in sunscreen products, which protect skin from UV attack. They are used frequently in plastics, including cosmetics and films. Different UV stabilizers are utilized depending upon the substrate, intended functional life, and sensitivity to UV degradation. UV stabilizers, such as benzophenones, work by absorbing the UV radiation and preventing the formation of free radicals. Depending upon substitution, the UV absorption spectrum is changed to match the application. Concentrations normally range from 0.05% to 2%, with some applications up to 5%.
Frequently, glass can be a better alternative to polymers when it comes to UV degradation. Most of the commonly used glass types are highly resistant to UV radiation. Explosion protection lamps for oil rigs for example can be made either from polymer or glass. Here, the UV radiation and rough weathers belabor the polymer so much, that the material has to be replaced frequently.
Poly(ethylene-naphthalate) (PEN) can be protected by applying a zinc oxide coating, which acts as protective film reducing the diffusion of oxygen. Zinc oxide can also be used on polycarbonate (PC) to decrease the oxidation and photo-yellowing rate caused by solar radiation. | 0 | Theoretical and Fundamental Chemistry |
Substrate or product inhibition is where either an enzymes substrate or product also act as an inhibitor. This inhibition may follow the competitive, uncompetitive or mixed patterns. In substrate inhibition there is a progressive decrease in activity at high substrate concentrations, potentially from an enzyme having two competing substrate-binding sites. At low substrate, the high-affinity site is occupied and normal kinetics are followed. However, at higher concentrations, the second inhibitory site becomes occupied, inhibiting the enzyme. Product inhibition (either the enzyme's own product, or a product to an enzyme downstream in its metabolic pathway) is often a regulatory feature in metabolism and can be a form of negative feedback. | 1 | Applied and Interdisciplinary Chemistry |
The first uses of ferrouranium date back to 1897, when the French government attempted to use it for guns. Ferrouranium is used as a deoxidizer (more powerful than ferrovanadium), for denitrogenizing steel, for forming carbides, and as an alloying element. In ferrous alloys, uranium increases the elastic limit and the tensile strength. In high speed steels, it has been used to increase toughness and strength in amounts between 0.05 and 5%. Uranium-alloyed steels can be used at very low temperatures; nickel-uranium alloys are resistant to even very aggressive chemicals, including aqua regia. | 1 | Applied and Interdisciplinary Chemistry |
In biochemistry, two biopolymers are antiparallel if they run parallel to each other but with opposite directionality (alignments). An example is the two complementary strands of a DNA double helix, which run in opposite directions alongside each other. | 1 | Applied and Interdisciplinary Chemistry |
Barium chlorate, when burned with a fuel, produces a vibrant green light. Because it is an oxidizer, a chlorine donor, and contains a metal, this compound produces a green color that is unparalleled. However, due to the instability of all chlorates to sulfur, acids, and ammonium ions, chlorates have been banned from use in class C fireworks in the United States. Therefore, more and more firework producers have begun to use more stable compound such as barium nitrate and barium carbonate. | 0 | Theoretical and Fundamental Chemistry |
An alteration in copy number state with respect to a single-copy reference locus is referred to as a “copy number variation” (CNV) if it appears in germline cells, or a copy number alteration (CNA) if it appears in somatic cells. A CNV or CNA could be due to a deletion or amplification of a locus with respect to the number of copies of the reference locus present in the cell, and together, they are major contributors to variability in the human genome. They have been associated with cancers; neurological, psychiatric, and autoimmune diseases; and adverse drug reactions. However, it is difficult to measure these allelic variations with high precision using other methods such as qPCR, thus making phenotypic and disease associations with altered CNV status challenging.
The large number of “digitized,” endpoint measurements made possible by sample partitioning enables dPCR to resolve small differences in copy number with better accuracy and precision when compared to other methods such as SNP-based microarrays or qPCR. qPCR is limited in its ability to precisely quantify gene amplifications in several diseases, including Crohn’s disease, HIV-1 infection, and obesity.
dPCR was designed to measure the concentration of a nucleic acid target in copies per unit volume of the sample. When operating in dilute reactions where less than ~10% of the partitions contain a desired target (referred to as “limiting dilution”), copy number can be estimated by comparing the number of fluorescent droplets arising from a target CNV with the number of fluorescent droplets arising from an invariant single-copy reference locus. In fact, both at these lower target concentrations and at higher ones where multiple copies of the same target can co-localize to a single partition, Poisson statistics are used to correct for these multiple occupancies to give a more accurate value for each target’s concentration.
Digital PCR has been used to uncover both germline and somatic variation in gene copy number between humans and to study the link between amplification of HER2 (ERBB2) and breast cancer progression. | 1 | Applied and Interdisciplinary Chemistry |
Schering AG filed for a patent for NETA in June 1957, and the patent was issued in December 1960. The drug was first marketed, by Parke-Davis as Norlestrin in the United States, in March 1964. This was a combination formulation of 2.5 mg NETA and 50 μg ethinylestradiol and was indicated as an oral contraceptive. Other early brand names of NETA used in oral contraceptives included Minovlar and Anovlar. | 1 | Applied and Interdisciplinary Chemistry |
The Kostanecki acylation is a method used in organic synthesis to form chromones or coumarins by acylation of O-hydroxyaryl ketones with aliphatic acid anhydrides, followed by cyclization. If benzoic anhydride (or benzoyl chloride) is used, a particular type of chromone called a flavone is obtained. | 0 | Theoretical and Fundamental Chemistry |
Light2CAT was a project funded by the European Commission from 2012 to 2015. It aimed to develop a modified that can absorb visible light and include this modified into construction concrete. The degrades harmful pollutants such as NOx into NO. The modified TiO is in use in Copenhagen and Holbæk, Denmark, and Valencia, Spain. This “self-cleaning” concrete led to a 5-20% reduction in NOx over the course of a year. | 0 | Theoretical and Fundamental Chemistry |
The two terminal N–O bonds are nearly equivalent and relatively short, at 1.20 and 1.21 Å. This can be explained by theories of resonance; the two major canonical forms show some double bond character in these two bonds, causing them to be shorter than N–O single bonds. The third N–O bond is elongated because its O atom is bonded to H atom, with a bond length of 1.41 Å in the gas phase. The molecule is slightly aplanar (the nitro group| and NOH planes are tilted away from each other by 2°) and there is restricted rotation about the N–OH single bond. | 0 | Theoretical and Fundamental Chemistry |
High-content screening (HCS), also known as high-content analysis (HCA) or cellomics, is a method that is used in biological research and drug discovery to identify substances such as small molecules, peptides, or RNAi that alter the phenotype of a cell in a desired manner. Hence high content screening is a type of phenotypic screen conducted in cells involving the analysis of whole cells or components of cells with simultaneous readout of several parameters. HCS is related to high-throughput screening (HTS), in which thousands of compounds are tested in parallel for their activity in one or more biological assays, but involves assays of more complex cellular phenotypes as outputs. Phenotypic changes may include increases or decreases in the production of cellular products such as proteins and/or changes in the morphology (visual appearance) of the cell. Hence HCA typically involves automated microscopy and image analysis. Unlike high-content analysis, high-content screening implies a level of throughput which is why the term "screening" differentiates HCS from HCA, which may be high in content but low in throughput.
In high content screening, cells are first incubated with the substance and after a period of time, structures and molecular components of the cells are analyzed. The most common analysis involves labeling proteins with fluorescent tags, and finally changes in cell phenotype are measured using automated image analysis. Through the use of fluorescent tags with different absorption and emission maxima, it is possible to measure several different cell components in parallel. Furthermore, the imaging is able to detect changes at a subcellular level (e.g., cytoplasm vs. nucleus vs. other organelles). Therefore, a large number of data points can be collected per cell. In addition to fluorescent labeling, various label free assays have been used in high content screening. | 1 | Applied and Interdisciplinary Chemistry |
Fig. 3 shows an AFM, which typically consists of the following features. Numbers in parentheses correspond to numbered features in Fig. 3. Coordinate directions are defined by the coordinate system (0).
The small spring-like cantilever (1) is carried by the support (2). Optionally, a piezoelectric element (typically made of a ceramic material) (3) oscillates the cantilever (1). The sharp tip (4) is fixed to the free end of the cantilever (1). The detector (5) records the deflection and motion of the cantilever (1). The sample (6) is mounted on the sample stage (8). An xyz drive (7) permits to displace the sample (6) and the sample stage (8) in x, y, and z directions with respect to the tip apex (4). Although Fig. 3 shows the drive attached to the sample, the drive can also be attached to the tip, or independent drives can be attached to both, since it is the relative displacement of the sample and tip that needs to be controlled. Controllers and plotter are not shown in Fig. 3.
According to the configuration described above, the interaction between tip and sample, which can be an atomic-scale phenomenon, is transduced into changes of the motion of cantilever, which is a macro-scale phenomenon. Several different aspects of the cantilever motion can be used to quantify the interaction between the tip and sample, most commonly the value of the deflection, the amplitude of an imposed oscillation of the cantilever, or the shift in resonance frequency of the cantilever (see section Imaging Modes). | 0 | Theoretical and Fundamental Chemistry |
When observing a gas, it is typical to specify a frame of reference or length scale. A larger length scale corresponds to a macroscopic or global point of view of the gas. This region (referred to as a volume) must be sufficient in size to contain a large sampling of gas particles. The resulting statistical analysis of this sample size produces the "average" behavior (i.e. velocity, temperature or pressure) of all the gas particles within the region. In contrast, a smaller length scale corresponds to a microscopic or particle point of view.
Macroscopically, the gas characteristics measured are either in terms of the gas particles themselves (velocity, pressure, or temperature) or their surroundings (volume). For example, Robert Boyle studied pneumatic chemistry for a small portion of his career. One of his experiments related the macroscopic properties of pressure and volume of a gas. His experiment used a J-tube manometer which looks like a test tube in the shape of the letter J. Boyle trapped an inert gas in the closed end of the test tube with a column of mercury, thereby making the number of particles and the temperature constant. He observed that when the pressure was increased in the gas, by adding more mercury to the column, the trapped gas' volume decreased (this is known as an inverse relationship). Furthermore, when Boyle multiplied the pressure and volume of each observation, the product was constant. This relationship held for every gas that Boyle observed leading to the law, (PV=k), named to honor his work in this field.
There are many mathematical tools available for analyzing gas properties. As gases are subjected to extreme conditions, these tools become more complex, from the Euler equations for inviscid flow to the Navier–Stokes equations that fully account for viscous effects. These equations are adapted to the conditions of the gas system in question. Boyle's lab equipment allowed the use of algebra to obtain his analytical results. His results were possible because he was studying gases in relatively low pressure situations where they behaved in an "ideal" manner. These ideal relationships apply to safety calculations for a variety of flight conditions on the materials in use. The high technology equipment in use today was designed to help us safely explore the more exotic operating environments where the gases no longer behave in an "ideal" manner. This advanced math, including statistics and multivariable calculus, makes possible the solution to such complex dynamic situations as space vehicle reentry. An example is the analysis of the space shuttle reentry pictured to ensure the material properties under this loading condition are appropriate. In this flight regime, the gas is no longer behaving ideally. | 0 | Theoretical and Fundamental Chemistry |
Ethanol is dehydrogenated to acetaldehyde by alcohol dehydrogenase, and further into acetyl CoA by acetaldehyde dehydrogenase. During this reaction 2 NADH are produced. If large amounts of ethanol are present, then large amounts of NADH are produced, leading to a depletion of NAD. Thus, the conversion of pyruvate to lactate is increased due to the associated regeneration of NAD. Therefore, anion-gap metabolic acidosis (lactic acidosis) may ensue in ethanol poisoning.
The increased NADH/NAD+ ratio also can cause hypoglycemia in an (otherwise) fasting individual who has been drinking and is dependent on gluconeogenesis to maintain blood glucose levels. Alanine and lactate are major gluconeogenic precursors that enter gluconeogenesis as pyruvate. The high NADH/NAD+ ratio shifts the lactate dehydrogenase equilibrium to lactate, so that less pyruvate can be formed and, therefore, gluconeogenesis is impaired. | 1 | Applied and Interdisciplinary Chemistry |
John William Draper (May 5, 1811 – January 4, 1882) was an English scientist, philosopher, physician, chemist, historian and photographer. He is credited with pioneering portrait photography (1839–40) and producing the first detailed photograph of the moon in 1840. He was also the first president of the American Chemical Society (1876–77) and a founder of the New York University School of Medicine.
One of Drapers books, the History of the Conflict between Religion and Science', popularised the conflict thesis proposing intrinsic hostility in the relationship between religion and science. It was widely read and was translated into several languages.
His son, Henry Draper, and his granddaughter, Antonia Maury, were astronomers. His granddaughter, Carlotta Maury (Antonia's younger sister), was a paleontologist. His eldest son, John Christopher Draper, was a chemist; and son Daniel Draper, a meteorologist. | 0 | Theoretical and Fundamental Chemistry |
Various methods have been proposed to achieve the suitable alignment of monomers in the crystal. These methods can be divided into two categories:
An obvious method is to introduce supramolecular interactions to the monomer. Popular choices include π - π stacking interactions, hydrogen/halogen bonding interactions, and Coulomb interactions. These interactions are sometimes inherent properties of reaction groups, such as π-π interaction between azide and acetylene group, or stacking force between biphenylethylene unit. Sometimes the side groups are introduced to form a network within the crystal.
The other strategy is to take advantage of the so-called "host-guest" assembly. In this case, the monomer is designed to link to a "host" molecule, while the host molecule is in charge of forming the ordered network. The host molecule stays intact during the polymerization. Such strategies simplify the synthesis of monomer. | 0 | Theoretical and Fundamental Chemistry |
AOAC has published the peer-reviewed Journal of AOAC International bimonthly since 1915. They also publish the Official Methods of Analysis (OMA) in hard copy and through the on-line database. The magazine Inside Laboratory Management is published bimonthly for members. | 0 | Theoretical and Fundamental Chemistry |
Sulfenyl fluorides and bromides are also known. Simple sulfenyl iodides are unknown because they are unstable with respect to the disulfide and iodine:
Sulfenyl iodides can be isolated as stable compounds if they bear alkyl steric protecting groups as part of a cavity-shaped framework, illustrating the technique of kinetic stabilization of a reactive functionality, as in the case of sulfenic acids.
A related class of compounds are the alkylsulfur trichlorides, as exemplified by methylsulfur trichloride, .
The corresponding selenenyl halides, , are more commonly encountered in the laboratory. Sulfenyl chlorides are used in the production of agents used in the vulcanization of rubber. | 0 | Theoretical and Fundamental Chemistry |
Noise-immune cavity-enhanced optical-heterodyne molecular spectroscopy (NICE-OHMS) is an ultra-sensitive laser-based absorption technique that utilizes laser light to assess the concentration or the amount of a species in gas phase by absorption spectrometry (AS). | 0 | Theoretical and Fundamental Chemistry |
A foam is, in many cases, a multi-scale system.
One scale is the bubble: material foams are typically disordered and have a variety of bubble sizes. At larger sizes, the study of idealized foams is closely linked to the mathematical problems of minimal surfaces and three-dimensional tessellations, also called honeycombs. The Weaire–Phelan structure is considered the best possible (optimal) unit cell of a perfectly ordered foam, while Plateau's laws describe how soap-films form structures in foams.
At lower scale than the bubble is the thickness of the film for metastable foams, which can be considered a network of interconnected films called lamellae. Ideally, the lamellae connect in triads and radiate 120° outward from the connection points, known as Plateau borders.
An even lower scale is the liquid–air interface at the surface of the film. Most of the time this interface is stabilized by a layer of amphiphilic structure, often made of surfactants, particles (Pickering emulsion), or more complex associations. | 0 | Theoretical and Fundamental Chemistry |
The crystal structure of NMT reveals two identical subunits, each with its own myristoyl CoA binding site. Each subunit consists of a large saddle-shaped β-sheet surrounded by α-helices. The symmetry of the fold is pseudo twofold. Myristoyl CoA binds at the N-terminal portion, while the C-terminal end binds the protein. | 1 | Applied and Interdisciplinary Chemistry |
An abiogenic substance or process does not result from the present or past activity of living organisms. Abiogenic products may, e.g., be minerals, other inorganic compounds, as well as simple organic compounds (e.g. extraterrestrial methane, see also abiogenesis). | 0 | Theoretical and Fundamental Chemistry |
Perovskite materials exhibit many interesting and intriguing properties from both the theoretical and the application point of view. Colossal magnetoresistance, ferroelectricity, superconductivity, charge ordering, spin dependent transport, high thermopower and the interplay of structural, magnetic and transport properties are commonly observed features in this family. These compounds are used as sensors and catalyst electrodes in certain types of fuel cells and are candidates for memory devices and spintronics applications.
Many superconducting ceramic materials (the high temperature superconductors) have perovskite-like structures, often with 3 or more metals including copper, and some oxygen positions left vacant. One prime example is yttrium barium copper oxide which can be insulating or superconducting depending on the oxygen content.
Chemical engineers are considering a cobalt-based perovskite material as a replacement for platinum in catalytic converters for diesel vehicles. | 0 | Theoretical and Fundamental Chemistry |
Mississippi basin
* The Greater Twin Cities area of Minneapolis and St. Paul, Minnesota features two important Mississippi confluences. Near historical Fort Snelling and the town of Mendota—about 9 miles downstream on the Mississippi from Minneapolis—the Minnesota River flows into the Mississippi at Pike Island. The area around this confluence is a location of spiritual, cultural, and historical significance to the Dakota people and is also the site of the earliest European settlements in the Twin Cities area. About 30 miles further downstream from the Minnesota-Mississippi confluence—and 25 miles downstream from St. Paul—the Mississippi joins with the St. Croix River near Hastings, Minnesota, and Prescott, Wisconsin.
* Vicksburg, Mississippi lies atop bluffs overlooking the confluence of the Mississippi River with its tributary the Yazoo. Both rivers, as well as the bluffs, played an important role in the Vicksburg Campaign, a pivotal event of the American Civil War.
* The Missouri River flows into the Mississippi River at Jones-Confluence Point State Park, just north of St. Louis, Missouri. Slightly further upstream, the Illinois River flows into the Mississippi.
* The Madison, Jefferson and Gallatin Rivers in Three Forks, Montana form the confluence of the Missouri River.
* At Keokuk, Iowa, the Des Moines River flows into the Mississippi. This forms the political tripoint between the U.S. states of Iowa, Missouri, and Illinois.
* Just south of Cairo, Illinois, the Ohio River flows into the Mississippi, forming the tripoint between the states of Illinois, Missouri, and Kentucky.
* The Ohio River is formed by the confluence of the Monongahela and Allegheny rivers, located in Pittsburgh, Pennsylvania. The site is of great historical significance; in the 1970s it was upgraded by the creation of Point State Park, highlighted by a large fountain.
Atlantic watersheds
* At Harpers Ferry, West Virginia, the Shenandoah River flows into the Potomac River, at the tripoint of the U.S. states of Virginia, West Virginia, and Maryland.
* At Philadelphia, Pennsylvania, the Schuylkill River flows into the Delaware River, next to the former Philadelphia Naval Shipyard; the site remains industrial.
* At Cohoes, New York, a few miles north of Albany, the Mohawk River flows into the Hudson in three channels separated by islands. The confluence is historically important: upstream traffic on or along the Hudson often took a left turn at the Mohawk, which offers a uniquely level passageway through the Appalachian Mountains that assisted commerce and the settlement of the West.
* At Ottawa, the capital of Canada, the Rideau River flows—unusually, as a waterfall—into the Ottawa River; see Rideau Falls. On the island separating the two portions of the falls is a park with military monuments, among them the Ottawa Memorial.
* The Hochelaga Archipelago, including the island and city of Montreal, is located where the Ottawa River flows into the St. Lawrence River in Quebec, Canada.
* Winnipeg, Canada, is at the confluence of the Red River, and the Assiniboine River. The area is referred to as The Forks by locals, and has been an important trade location for over 6000 years.
Pacific watersheds
* The Green River flows into the Colorado River at the heart of Canyonlands National Park in Utah's Canyon Country.
* The Snake River flows into the Columbia River at Sacagawea State park near the Tri-Cities of Washington. It should also be noted that the significant Yakima river also flows into the Columbia just a few miles upstream, thus giving the region the unofficial preposition of Three Rivers
* In Portland, Oregon, the Willamette River flows into the Columbia at Kelley Point Park, built on land acquired from the Port of Portland in 1984.
* Lytton, British Columbia, Canada, is located at the confluence of the muddy Fraser River and the clearer Thompson River. | 1 | Applied and Interdisciplinary Chemistry |
The microdialysis principle was first employed in the early 1960s, when push-pull canulas and dialysis sacs were implanted into animal tissues, especially into rodent brains, to directly study the tissues biochemistry. While these techniques had a number of experimental drawbacks, such as the number of samples per animal or no/limited time resolution, the invention of continuously perfused dialytrodes in 1972 helped to overcome some of these limitations. Further improvement of the dialytrode concept resulted in the invention of the "hollow fiber", a tubular semipermeable membrane with a diameter of ~200-300μm, in 1974. Todays most prevalent shape, the needle probe, consists of a shaft with a hollow fiber at its tip and can be inserted by means of a guide cannula into the brain and other tissues. An alternative method, open flow micro-perfusion (OFM), replaces the membrane with macroscopic openings which facilitates sampling of lipophilic and hydrophilic compounds, protein bound and unbound drugs, neurotransmitters, peptides and proteins, antibodies, nanoparticles and nanocarriers, enzymes and vesicles. | 1 | Applied and Interdisciplinary Chemistry |
A Trisonic Wind Tunnel (TWT) is a wind tunnel so named because it is capable of testing in three speed regimes – subsonic, transonic, and supersonic. The earliest known trisonic wind tunnel was dated to 1950 and was located in El Segundo, California before it closed in 2007. Other trisonic wind tunnels currently in operation are those located at NASAs Marshall Space Flight Center, National Researach Council Canadas 1.5 m Trisonic Wind Tunnel Research Facility and the French-German Research Institute of Saint-Louis, ISRO's Vikram Sarabhai Space Centre(VSSC) in Thiruvananthapuram, India. | 1 | Applied and Interdisciplinary Chemistry |
Tube bending as a process starts with loading a tube into a tube or pipe bender and clamping it into place between two dies, the clamping block and the forming die. The tube is also loosely held by two other dies, the wiper die and the pressure die.
The process of tube bending involves using mechanical force to push stock material pipe or tubing against a die, forcing the pipe or tube to conform to the shape of the die. Often, stock tubing is held firmly in place while the end is rotated and rolled around the die. Other forms of processing including pushing stock through rollers that bend it into a simple curve. For some tube bending processing, a mandrel is placed inside the tube to prevent collapsing. The tube is held in tension by a wiper die to prevent any creasing during stress. A wiper die is usually made of a softer alloy such as aluminum or brass to avoid scratching or damaging the material being bent.
Much of the tooling is made of hardened steel or tool steel to maintain and prolong the tool's life. However, when there is a concern of scratching or gouging the work piece, a softer material such as aluminum or bronze is utilized. For example, the clamping block, rotating form block and pressure die are often formed from hardened steel because the tubing is not moving past these parts of the machine. The pressure die and the wiping die are formed from aluminum or bronze to maintain the shape and surface of the work piece as it slides by.
Pipe bending machines are typically human powered, pneumatic powered, hydraulic assisted, hydraulic driven, or electric servomotor. | 1 | Applied and Interdisciplinary Chemistry |
In December 2020, the Chinese experimental nuclear fusion reactor HL-2M achieved its first plasma discharge. In May 2021, Experimental Advanced Superconducting Tokamak (EAST) announced a new world record for superheated plasma, sustaining a temperature of 120 M°C for 101 seconds and a peak of 160 M°C for 20 seconds. In December 2021 EAST set a new world record for high temperature (70 M°C) plasma of 1,056 seconds.
In 2020, Chevron Corporation announced an investment in start-up Zap Energy, co-founded by British entrepreneur and investor, Benj Conway, together with physicists Brian Nelson and Uri Shumlak from University of Washington. In 2021 the company raised $27.5 million in Series B funding led by Addition.
In 2021, the US DOE launched the INFUSE program, a public-private knowledge sharing initiative involving a PPPL, MIT Plasma Science and Fusion Center and Commonwealth Fusion Systems partnership, together with partnerships with TAE Technologies, Princeton Fusion Systems, and Tokamak Energy. In 2021, DOE's Fusion Energy Sciences Advisory Committee approved a strategic plan to guide fusion energy and plasma physics research that included a working power plant by 2040, similar to Canadian, Chinese, and U.K. efforts.
In January 2021, SuperOx announced the commercialization of a new superconducting wire, with more than 700 A/mm2 current capability.
TAE Technologies announced that its Norman device had sustained a temperature of about 60 million degrees C for 30 milliseconds, 8 and 10 times higher, respectively, than the company's previous devices. The duration was claimed to be limited by the power supply rather than the device.
In August 2021, the National Ignition Facility recorded a record-breaking 1.3 megajoules of energy created from fusion which is the first example of the Lawson criterion being surpassed in a laboratory.
In February 2022, JET sustained 11 MW and a Q value of 0.33 for over 5 seconds, outputting 59.7 megajoules, using a mix of deuterium and tritium for fuel. In March 2022 it was announced that Tokamak Energy achieved a record plasma temperature of 100 million kelvins, inside a commercial compact tokamak.
In October 2022, the Korea Superconducting Tokamak Advanced Research (KSTAR) reached a record plasma duration of 45 seconds, sustaining the high-temperature fusion plasma over the 100 million degrees Celsus based on the integrated real-time RMP control for ELM-less H-mode, i.e. fast ions regulated enhancement (FIRE) mode, machine learning algorithm, and 3D field optimization via an edge-localized RMP.
In December 2022, the NIF achieved the first scientific breakeven controlled fusion experiment, with an energy gain of 1.5.
In February 2024, the KSTAR tokamak set a new record (shot #34705) for the longest duration (102 seconds) of a magnetically confined plasma. The plasma was operated in ELM-less H-mode, with much better control of the error field than was possible previously. KSTAR also set a record (shot #34445) for the longest steady-state duration at a temperature of 100 million degrees Celsius (48 seconds). | 0 | Theoretical and Fundamental Chemistry |
A spectacular example of galvanic corrosion occurred in the Statue of Liberty when regular maintenance checks in the 1980s revealed that corrosion had taken place between the outer copper skin and the wrought iron support structure. Although the problem had been anticipated when the structure was built by Gustave Eiffel to Frédéric Bartholdi's design in the 1880s, the insulation layer of shellac between the two metals had failed over time and resulted in rusting of the iron supports. An extensive renovation was carried out with replacement of the original insulation with PTFE. The structure was far from unsafe owing to the large number of unaffected connections, but it was regarded as a precautionary measure to preserve a national symbol of the United States. | 1 | Applied and Interdisciplinary Chemistry |
Sum frequency generation spectroscopy (SFG) is a nonlinear laser spectroscopy technique used to analyze surfaces and interfaces. It can be expressed as a sum of a series of Lorentz oscillators. In a typical SFG setup, two laser beams mix at an interface and generate an output beam with a frequency equal to the sum of the two input frequencies, traveling in a direction allegedly given by the sum of the incident beams' wavevectors. The technique was developed in 1987 by Yuen-Ron Shen and his students as an extension of second harmonic generation spectroscopy and rapidly applied to deduce the composition, orientation distributions, and structural information of molecules at gas–solid, gas–liquid and liquid–solid interfaces. Soon after its invention, Philippe Guyot-Sionnest extended the technique to obtain the first measurements of electronic and vibrational dynamics at surfaces. SFG has advantages in its ability to be monolayer surface sensitive, ability to be performed in situ (for example aqueous surfaces and in gases), and its capability to provide ultrafast time resolution. SFG gives information complementary to infrared and Raman spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
Several components of the signaling cascade that mediates the HMB-induced increase in human skeletal muscle protein synthesis have been identified in vivo. Similar to HMBs metabolic precursor, , HMB has been shown to increase protein synthesis in human skeletal muscle via phosphorylation of the mechanistic target of rapamycin (mTOR) and subsequent activation of , which leads to protein biosynthesis in cellular ribosomes via phosphorylation of mTORC1s immediate targets (i.e., the p70S6 kinase and the translation repressor protein 4EBP1). Supplementation with HMB in several non-human animal species has been shown to increase the serum concentration of growth hormone and insulin-like growth factor 1 (IGF-1) via an unknown mechanism, in turn promoting protein synthesis through increased mTOR phosphorylation. Based upon limited clinical evidence in humans, supplemental HMB appears to increase the secretion of growth hormone and IGF-1 in response to resistance exercise.
, the signaling cascade that mediates the HMB-induced reduction in muscle protein breakdown has not been identified in living humans, although it is well-established that it attenuates proteolysis in humans in vivo. Unlike , HMB attenuates muscle protein breakdown in an insulin-independent manner in humans. HMB is believed to reduce muscle protein breakdown in humans by inhibiting the 19S and 20S subunits of the ubiquitin–proteasome system in skeletal muscle and by inhibiting apoptosis of skeletal muscle nuclei via unidentified mechanisms.
Based upon animal studies, HMB appears to be metabolized within skeletal muscle into cholesterol, which may then be incorporated into the muscle cell membrane, thereby enhancing membrane integrity and function. The effects of HMB on muscle protein metabolism may help stabilize muscle cell structure. One review suggested that the observed HMB-induced reduction in the plasma concentration of muscle damage biomarkers (i.e., muscle enzymes such as creatine kinase and lactate dehydrogenase) in humans following intense exercise may be due to a cholesterol-mediated improvement in muscle cell membrane function.
HMB has been shown to stimulate the proliferation, differentiation, and fusion of human myosatellite cells in vitro, which potentially increases the regenerative capacity of skeletal muscle, by increasing the protein expression of certain myogenic regulatory factors (e.g., myoD and myogenin) and gene transcription factors (e.g., MEF2). HMB-induced human myosatellite cell proliferation in vitro is mediated through the phosphorylation of the mitogen-activated protein kinases ERK1 and ERK2. HMB-induced human myosatellite differentiation and accelerated fusion of myosatellite cells into muscle tissue in vitro is mediated through the phosphorylation of Akt, a serine/threonine-specific protein kinase. | 1 | Applied and Interdisciplinary Chemistry |
ppGpp and pppGpp were first identified by Michael Cashel in 1969. These nucleotides were found to accumulate rapidly in Escherichia coli cells starved for amino acids and inhibit synthesis of ribosomal and transfer RNAs. It is now known that (p)ppGpp is also produced in response to other stressors including carbon and phosphate starvation. Historically, literature surrounding (p)ppGpp have given conflicting findings and information on its role in bacterial stress responses. | 1 | Applied and Interdisciplinary Chemistry |
There may be leftover embryos or eggs from IVF procedures if the person for whom they were originally created has successfully carried one or more pregnancies to term, and no longer wishes to use them. With the patient's permission, these may be donated to help others conceive by means of third party reproduction.
In embryo donation, these extra embryos are given to others for transfer, with the goal of producing a successful pregnancy. Embryo recipients have genetic issues or poor-quality embryos or eggs of their own. The resulting child is considered the child of whoever birthed them, and not the child of the donor, the same as occurs with egg donation or sperm donation. As per The National Infertility Association, typically, genetic parents donate the eggs or embryos to a fertility clinic where they are preserved by oocyte cryopreservation or embryo cryopreservation until a carrier is found for them. The process of matching the donation with the prospective parents is conducted by the agency itself, at which time the clinic transfers ownership of the embryos to the prospective parent(s).
Alternatives to donating unused embryos are destroying them (or having them transferred at a time when pregnancy is very unlikely), keeping them frozen indefinitely, or donating them for use in research (rendering them non-viable). Individual moral views on disposing of leftover embryos may depend on personal views on the beginning of human personhood and the definition and/or value of potential future persons, and on the value that is given to fundamental research questions. Some people believe donation of leftover embryos for research is a good alternative to discarding the embryos when patients receive proper, honest and clear information about the research project, the procedures and the scientific values.
During the embryo selection and transfer phases, many embryos may be discarded in favour of others. This selection may be based on criteria such as genetic disorders or the sex. One of the earliest cases of special gene selection through IVF was the case of the Collins family in the 1990s, who selected the sex of their child.
The ethic issues remain unresolved as no worldwide consensus exists in science, religion, and philosophy on when a human embryo should be recognised as a person. For those who believe that this is at the moment of conception, IVF becomes a moral question when multiple eggs are fertilised, begin development, and only a few are chosen for uterus transfer.
If IVF were to involve the fertilisation of only a single egg, or at least only the number that will be transferred, then this would not be an issue. However, this has the chance of increasing costs dramatically as only a few eggs can be attempted at a time. As a result, the couple must decide what to do with these extra embryos. Depending on their view of the embryo's humanity or the chance the couple will want to try to have another child, the couple has multiple options for dealing with these extra embryos. Couples can choose to keep them frozen, donate them to other infertile couples, thaw them, or donate them to medical research. Keeping them frozen costs money, donating them does not ensure they will survive, thawing them renders them immediately unviable, and medical research results in their termination. In the realm of medical research, the couple is not necessarily told what the embryos will be used for, and as a result, some can be used in stem cell research.
In February 2024, the Alabama Supreme Court ruled in LePage v. Center for Reproductive Medicine that cryopreserved embryos were "persons" or "extrauterine children". After Dobbs v. Jackson Women's Health Organization (2022), some antiabortionists had hoped to get a judgement that fetuses and embryos were "person[s]". | 1 | Applied and Interdisciplinary Chemistry |
An electrophoretic mobility shift assay (EMSA) or mobility shift electrophoresis, also referred as a gel shift assay, gel mobility shift assay, band shift assay, or gel retardation assay, is a common affinity electrophoresis technique used to study protein–DNA or protein–RNA interactions. This procedure can determine if a protein or mixture of proteins is capable of binding to a given DNA or RNA sequence, and can sometimes indicate if more than one protein molecule is involved in the binding complex. Gel shift assays are often performed in vitro concurrently with DNase footprinting, primer extension, and promoter-probe experiments when studying transcription initiation, DNA gang replication, DNA repair or RNA processing and maturation, as well as pre-mRNA splicing. Although precursors can be found in earlier literature, most current assays are based on methods described by Garner and Revzin and Fried and Crothers. | 1 | Applied and Interdisciplinary Chemistry |
Pyridine has historically been added to foods to give them a bitter flavour, although this practise is now banned in the U.S. It may still be added to ethanol to make it unsuitable for drinking. | 0 | Theoretical and Fundamental Chemistry |
*Ohshima. H. Theory of Colloid and Interfacial Electric Phenomena, Elsevier, 2006.
*Duval, J.F.L. and oth. Langmuir, 21, 11268-11282 (2005). | 0 | Theoretical and Fundamental Chemistry |
The Klein–Nishina formula was derived in 1928 by Oskar Klein and Yoshio Nishina, and was one of the first results obtained from the study of quantum electrodynamics. Consideration of relativistic and quantum mechanical effects allowed development of an accurate equation for the scattering of radiation from a target electron. Before this derivation, the electron cross section had been classically derived by the British physicist and discoverer of the electron, J.J. Thomson. However, scattering experiments showed significant deviations from the results predicted by the Thomson cross section. Further scattering experiments agreed perfectly with the predictions of the Klein–Nishina formula. | 0 | Theoretical and Fundamental Chemistry |
Ca is required to activate the binding. Ca binds to the protein and carbohydrate by non covalent bond. Mannose-binding protein (MBP) contains the C-type CRD. | 0 | Theoretical and Fundamental Chemistry |
The chiral pool is a "collection of abundant enantiopure building blocks provided by nature" used in synthesis. In other words, a chiral pool would be a large quantity of common organic enantiomers. Contributors to the chiral pool are amino acids, sugars, and terpenes. Their use improves the efficiency of total synthesis. Not only does the chiral pool contribute a premade carbon skeleton, their chirality is usually preserved in the remainder of the reaction sequence.
This strategy is especially helpful if the desired molecule resembles cheap enantiopure natural products. Many times, suitable enantiopure starting materials cannot be identified. The alternative to the use of the chiral pool is asymmetric synthesis, whereby achiral precursors are employed or racemic intermediates are resolved. | 0 | Theoretical and Fundamental Chemistry |
Currently there are many methods used to determine the zygosity status of a gene at a particular locus. These methods include the use of PCR with specifically designed probes to detect the variants of the genes (SNP typing is the simplest case). In cases where longer stretches of variation is implicated, post PCR analysis of the amplicons may be required. Changes in enzyme restriction, electrophoretic and chromatographic profiles can be measured. These methods are usually more time-consuming and increase the risk of amplicon contamination in the laboratory, due to the need to work with high concentrations of amplicons in the lab post-PCR. The use of HRM reduces the time required for analysis and the risk of contamination. HRM is a more cost-effective solution and the high resolution element not only allows the determination of homo and heterozygosity, it also resolves information about the type of homo and heterozygosity, with different gene variants giving rise to differing melt curve shapes. A study by Gundry et al. 2003, showed that fluorescent labelling of one primer (in the pair) has been shown to be favourable over using an intercalating dye such as SYBR green I. However, progress has been made in the development and use of improved intercalating dyes which reduce the issue of PCR inhibition and concerns over non-saturating intercalation of the dye. | 1 | Applied and Interdisciplinary Chemistry |
This complex is used as an indicator in analytical chemistry. The active ingredient is the [Fe(o-phen)] ion, which is a chromophore that can be oxidized to the ferric derivative [Fe(o-phen)]. The potential for this redox change is +1.06 volts in 1 M HSO. It is a popular redox indicator for visualizing oscillatory Belousov–Zhabotinsky reactions.
Ferroin is suitable as a redox indicator, as the color change is reversible, very pronounced and rapid, and the ferroin solution is stable up to 60 °C. It is the main indicator used in cerimetry.
Nitroferroin, the complex of iron(II) with 5-nitro-1,10-phenanthroline, has transition potential of +1.25 volts. It is more stable than ferroin, but in sulfuric acid with Ce ion it requires significant excess of the titrant. It is however useful for titration in perchloric acid or nitric acid solution, where cerium redox potential is higher.
The redox potential of the iron-phenanthroline complex can be varied between +0.84 V and +1.10 V by adjusting the position and number of methyl groups on the phenanthroline core. | 0 | Theoretical and Fundamental Chemistry |
The anthracene molecule admits three resonance structures, each with a circle in one ring and two sets of double bonds in the other two. Following the rule at point 4 exposed above, anthracene is better described by a superposition of these three equivalent structures, and an arrow is drawn to indicate the presence of a migrating π-sextet. Following the same line of reasoning, one can find migrating π-sextets in other molecules of the acene series, such as tetracene, pentacene, and hexacene. | 0 | Theoretical and Fundamental Chemistry |
Ashe's parents came to the United States from China to pursue PhDs; her father, C.C. Hsiao, taught aerospace engineering at the University of Minnesota, and her mother, Joyce, was a biochemist. She has three younger siblings.
Attending the St. Paul Academy and Summit School in the 1970s, Ashe's interest in the brain began in primary school, where she excelled in math, along with music. She obtained her undergraduate degree at Harvard University in 1975 in chemistry and physics, starting as a sophomore at the age of 17. She went on to earn her PhD in brain and cognitive sciences at MIT in 1981 and her MD from Harvard in 1982.
Ashe's husband, James is a neurologist; she has three children (two sons and a daughter). | 1 | Applied and Interdisciplinary Chemistry |
For small scale reactions, SF can be inconvenient since it is a gas and stainless steel reaction vessels are required. Many transformations require elevated temperatures. The reaction generates hydrogen fluoride. These concerns have led to interest in alternative fluorinating reagents. Selenium tetrafluoride, a liquid at room temperature, behaves similarly to SF. Diethylaminosulfur trifluoride (DAST) is a derivative of SF that is easier to handle, albeit more expensive. | 0 | Theoretical and Fundamental Chemistry |
Both ASR and aerial respiration require fish to travel to the top of water column and this behaviour increases the predation risks by aerial predators or other piscivores inhabiting near the surface of the water. To cope with the increased predation risk upon surfacing, some fish perform ASR or aerial respiration in schools to dilute the predation risk. When fish can visually detect the presence of their aerial predators, they simply refrain from surfacing, or prefer to surface in areas where they can be detected less easily (i.e. turbid, shaded areas). | 0 | Theoretical and Fundamental Chemistry |
Many important biological processes involve redox reactions. Before some of these processes can begin iron must be assimilated from the environment.
Cellular respiration, for instance, is the oxidation of glucose (CHO) to CO and the reduction of oxygen to water. The summary equation for cell respiration is:
The process of cell respiration also depends heavily on the reduction of NAD to NADH and the reverse reaction (the oxidation of NADH to NAD). Photosynthesis and cellular respiration are complementary, but photosynthesis is not the reverse of the redox reaction in cell respiration:
Biological energy is frequently stored and released by means of redox reactions. Photosynthesis involves the reduction of carbon dioxide into sugars and the oxidation of water into molecular oxygen. The reverse reaction, respiration, oxidizes sugars to produce carbon dioxide and water. As intermediate steps, the reduced carbon compounds are used to reduce nicotinamide adenine dinucleotide (NAD) to NADH, which then contributes to the creation of a proton gradient, which drives the synthesis of adenosine triphosphate (ATP) and is maintained by the reduction of oxygen. In animal cells, mitochondria perform similar functions.
Free radical reactions are redox reactions that occur as a part of homeostasis and killing microorganisms, where an electron detaches from a molecule and then reattaches almost instantaneously. Free radicals are a part of redox molecules and can become harmful to the human body if they do not reattach to the redox molecule or an antioxidant.
The term redox state is often used to describe the balance of GSH/GSSG, NAD/NADH and NADP/NADPH in a biological system such as a cell or organ. The redox state is reflected in the balance of several sets of metabolites (e.g., lactate and pyruvate, beta-hydroxybutyrate, and acetoacetate), whose interconversion is dependent on these ratios. Redox mechanisms also control some cellular processes. Redox proteins and their genes must be co-located for redox regulation according to the CoRR hypothesis for the function of DNA in mitochondria and chloroplasts. | 0 | Theoretical and Fundamental Chemistry |
The oxygen minimum zone (OMZ), sometimes referred to as the shadow zone, is the zone in which oxygen saturation in seawater in the ocean is at its lowest. This zone occurs at depths of about , depending on local circumstances. OMZs are found worldwide, typically along the western coast of continents, in areas where an interplay of physical and biological processes concurrently lower the oxygen concentration (biological processes) and restrict the water from mixing with surrounding waters (physical processes), creating a "pool" of water where oxygen concentrations fall from the normal range of 4–6 mg/L to below 2 mg/L. | 0 | Theoretical and Fundamental Chemistry |
Despite two distinct base-resolution methods being available for hm5dC, there are no base-resolution methods for detection of hm5C. | 1 | Applied and Interdisciplinary Chemistry |
Plants have evolved R genes (resistance genes) whose products mediate resistance to specific virus, bacteria, oomycete, fungus, nematode or insect strains. R gene products are proteins that allow recognition of specific pathogen effectors, either through direct binding or by recognition of the effector's alteration of a host protein. Many R genes encode NB-LRR proteins (proteins with nucleotide-binding and leucine-rich repeat domains, also known as NLR proteins or STAND proteins, among other names). Most plant immune systems carry a repertoire of 100–600 different R gene homologs. Individual R genes have been demonstrated to mediate resistance to specific virus, bacteria, oomycete, fungus, nematode or insect strains. R gene products control a broad set of disease resistance responses whose induction is often sufficient to stop further pathogen growth/spread.
Studied R genes usually confer specificity for particular strains of a pathogen species (those that express the recognized effector). As first noted by Harold Flor in his mid-20th century formulation of the gene-for-gene relationship, a plant R gene has specificity for a pathogen avirulence gene (Avr gene). Avirulence genes are now known to encode effectors. The pathogen Avr gene must have matched specificity with the R gene for that R gene to confer resistance, suggesting a receptor/ligand interaction for Avr and R genes. Alternatively, an effector can modify its host cellular target (or a molecular decoy of that target), and the R gene product (NLR protein) activates defenses when it detects the modified form of the host target or decoy. | 1 | Applied and Interdisciplinary Chemistry |
Weld-On is a division of IPS Corporation, a manufacturer of solvent cements, primers, and cleaners for PVC, CPVC, and ABS plastic piping systems. Weld-On products are commonly used for joining plastic pipes and fittings. Weld-On also manufactures specialty products from repair adhesives for leaking pipes, pipe thread sealants / joint compounds, to test plugs for pipeline pressure testing. Their products are most commonly utilized in the irrigation, industrial, pool & spa, electrical conduit, and plumbing industries.
Headquartered in California, Weld-On has operations throughout the United States, as well as in China, and a worldwide network of sales representatives and distributors. | 1 | Applied and Interdisciplinary Chemistry |
Many technological processes require control of liquid spreading over solid surfaces. When a drop is placed on a surface, it can completely wet, partially wet, or not wet the surface. By reducing the surface tension with surfactants, a nonwetting material can be made to become partially or completely wetting. The excess free energy (σ) of a drop on a solid surface is:
:* γ is the liquid–vapor interfacial tension
:* γ is the solid–liquid interfacial tension
:* γ is the solid–vapor interfacial tension
:* S is the area of liquid–vapor interface
:* P is the excess pressure inside liquid
:* R is the radius of droplet base
Based on this equation, the excess free energy is minimized when γ decreases, γ decreases, or γ increases. Surfactants are absorbed onto the liquid–vapor, solid–liquid, and solid–vapor interfaces, which modify the wetting behavior of hydrophobic materials to reduce the free energy. When surfactants are absorbed onto a hydrophobic surface, the polar head groups face into the solution with the tail pointing outward. In more hydrophobic surfaces, surfactants may form a bilayer on the solid, causing it to become more hydrophilic. The dynamic drop radius can be characterized as the drop begins to spread. Thus, the contact angle changes based on the following equation:
:* θ is initial contact angle
:* θ is final contact angle
:* τ is the surfactant transfer time scale
As the surfactants are absorbed, the solid–vapor surface tension increases and the edges of the drop become hydrophilic. As a result, the drop spreads. | 0 | Theoretical and Fundamental Chemistry |
Bhushan is a member of editorial board of
* Biomedical Chromatography, (John Wiley & Sons, UK, since Jan 1996);
* Bioanalysis (Future Science Group, UK, since 2011), and
* Acta Chromatographica (Akademiai Kiado, Hungary, since 2012). | 0 | Theoretical and Fundamental Chemistry |
The SI unit of conductivity is S/m and, unless otherwise qualified, it refers to 25 °C. More generally encountered is the traditional unit of μS/cm.
The commonly used standard cell has a width of 1 cm, and thus for very pure water in equilibrium with air would have a resistance of about 10 ohms, known as a megohm. Ultra-pure water could achieve 18 megohms or more. Thus in the past, megohm-cm was used, sometimes abbreviated to "megohm". Sometimes, conductivity is given in "microsiemens" (omitting the distance term in the unit). While this is an error, it can often be assumed to be equal to the traditional μS/cm. Often, by typographic limitations μS/cm is expressed as uS/cm.
The conversion of conductivity to the total dissolved solids depends on the chemical composition of the sample and can vary between 0.54 and 0.96. Typically, the conversion is done assuming that the solid is sodium chloride; 1 μS/cm is then equivalent to about 0.64 mg of NaCl per kg of water.
Molar conductivity has the SI unit S m mol. Older publications use the unit Ω cm mol. | 0 | Theoretical and Fundamental Chemistry |
Karsten Meyer (born May 17, 1968, in Herne, Germany) is a German inorganic chemist and Chair of Inorganic and General Chemistry at the Friedrich-Alexander University of Erlangen-Nürnberg (FAU). His research involves the coordination chemistry of transition metals as well as uranium coordination chemistry, small molecule activation with these coordination complexes, and the synthesis of new chelating ligands. He is the 2017 recipient of the Elhuyar-Goldschmidt Award of the Spanish Royal Society of Chemistry, the Ludwig-Mond Award of the Royal Society of Chemistry, and the L.A. Chugaev Commemorative Medal of the Russian Academy of Sciences, among other awards. He also serves as an Associate Editor of the journal Organometallics since 2014. | 0 | Theoretical and Fundamental Chemistry |
Fraser-Reid was born in Coleyville, Jamaica to William, an elementary school principal, and Laura, a teacher. He had five older siblings. Laura died when Fraser-Reid was only nine months old. He attended Excelsior High School and Clarendon College before moving to Canada to earn BSc (1959) and MSc (1961) at Queen's University in Ontario He went to University of Alberta to earn a PhD in 1964 under the supervision of Raymond Lemieux. He went to Imperial College London to do postdoctoral work for Nobel Laureate Sir Derek Barton from 1964 to 1966. | 0 | Theoretical and Fundamental Chemistry |
Archaeometallurgy is the study of the past use and production of metals by humans. It is a sub-discipline of archaeology and archaeological science. | 1 | Applied and Interdisciplinary Chemistry |
The Denigés' reagent is a reagent used for qualitative analysis. It was developed in 1898 by Georges Denigés (December 25, 1859–February 20, 1951), a French biochemist. | 0 | Theoretical and Fundamental Chemistry |
Drospirenone was patented in 1976 and introduced for medical use in 2000. Schering AG of Germany has been granted several patents on the production of drospirenone, including WIPO and US patents, granted in 1998 and 2000, respectively. It was introduced for medical use in combination with ethinylestradiol as a combined birth control pill in 2000. Drospirenone is sometimes described as a "fourth-generation" progestin based on its time of introduction. The medication was approved for use in menopausal hormone therapy in combination with estradiol in 2005. Drospirenone was introduced for use as a progestogen-only birth control pill in 2019. A combined birth control pill containing estetrol and drospirenone was approved in 2021. | 0 | Theoretical and Fundamental Chemistry |
The Electrochemical Society is a learned society (professional association) based in the United States that supports scientific inquiry in the field of electrochemistry solid-state science and related technology. The Society membership comprises more than 8,000 scientists and engineers in over 85 countries at all degree levels and in all fields of electrochemistry, solid-state science and related technologies. Additional support is provided by institutional members including corporations and laboratories.
ECS is a 501(c)(3) non-profit organization.
The Society publishes numerous journals including the Journal of The Electrochemical Society (the oldest peer-reviewed journal in its field), the Journal of Solid State Science and Technology, ECS Meeting Abstracts, ECS Transactions, and ECS Interface. The Society sponsors the ECS Monographs Series. These distinguished monographs, published by John Wiley & Sons, are the leading textbooks in their fields.
The ECS Digital Library on IOPscience encompasses over 160,000 journal and magazine articles and meeting abstracts. The Society supports open access through the Society’s initiative to make research freely available to world readers and free for authors to publish.
The Society has thirteen topic interest area divisions as well as regional sections in Asia, Europe, Latin America, the Middle East, North America, and Southern Asia; over 100 ECS student chapters are located in major universities in all of these regions as well as Eastern Europe and South Africa. Student members benefit from exposure to experts in their fields, sharing research, volunteer activities, and career development.
ECS administers numerous international awards and supports STEM educational and outreach efforts. | 0 | Theoretical and Fundamental Chemistry |
Because the intense red color of hemoglobin interferes with the readout of colorimetric or optical detection-based diagnostic tests, blood plasma separation is a common first step to increase diagnostic test accuracy. Plasma can be extracted from whole blood via integrated filters or via agglutination. | 1 | Applied and Interdisciplinary Chemistry |
Prp24 interacts with the U6 snRNA via its RRMs. It has been shown through chemical modification testing that nucleotides 39–57 of U6 (40–43 in particular) are involved in binding Prp24.
The LSm proteins are in a consistent configuration on the U6 RNA. It has been proposed that the LSm proteins and Prp24 interact both physically and functionally and the C-terminal motif of Prp24 is important for this interaction. The binding of Prp24 to U6 is enhanced by the binding of Lsm proteins to U6, as is binding of U4 and U6. It was revealed by electron microscopy that Prp24 may interact with the LSm protein ring at LSm2. | 1 | Applied and Interdisciplinary Chemistry |
An example of an isozyme is glucokinase, a variant of hexokinase which is not inhibited by glucose 6-phosphate. Its different regulatory features and lower affinity for glucose (compared to other hexokinases), allow it to serve different functions in cells of specific organs, such as control of insulin release by the beta cells of the pancreas, or initiation of glycogen synthesis by liver cells. Both these processes must only occur when glucose is abundant.
1.) The enzyme lactate dehydrogenase is a tetramer made of two different sub-units, the H-form and the M-form. These combine in different combinations depending on the tissue:
2.) Isoenzymes of creatine phosphokinase: Creatine kinase (CK) or creatine phosphokinase (CPK) catalyses the interconversion of phospho creatine to creatine .
CPK exists in 3 isoenzymes. Each isoenzymes is a dimer of 2 subunits M (muscle), B (brain) or both
3.) Isoenzymes of alkaline phosphatase: Six isoenzymes have been identified. The enzyme is a monomer, the isoenzymes are due to the differences in the carbohydrate content (sialic acid residues). The most important ALP isoenzymes are α-ALP, α-heat labile ALP, α-heat stable ALP, pre-β ALP and γ-ALP. Increase in α-heat labile ALP suggests hepatitis whereas pre-β ALP indicates bone diseases. | 1 | Applied and Interdisciplinary Chemistry |
Note that domain does not have to be a 2D domain: the method is applicable to higher dimensional domains using multidimensional noise fields. However, the visualization of the higher-dimensional LIC texture is problematic; one way is to use interactive exploration with 2D slices that are manually positioned and rotated. The domain does not have to be flat either; the LIC texture can be computed also for arbitrarily shaped 2D surfaces in 3D space. | 1 | Applied and Interdisciplinary Chemistry |
Emeléus died of heart failure at Addenbrooke's Hospital, Cambridge, on 2 December 1993. He was survived by his four children, his wife having predeceased him in January 1991. | 0 | Theoretical and Fundamental Chemistry |
Two types of threads are distinguished:
* Parallel (straight) threads, British Standard Pipe Parallel thread (BSPP; originally also known as British Standard Pipe Fitting thread/BSPF and British Standard Pipe Mechanical thread/BSPM), which have a constant diameter; denoted by the letter G.
* Taper threads, British Standard Pipe Taper thread (BSPT), whose diameter increases or decreases along the length of the thread; denoted by the letter R.
These can be combined into two types of joints:
; Jointing threads: These are pipe threads where pressure-tightness is made through the mating of two threads together. They always use a taper male thread, but can have either parallel or taper female threads. (In Europe, taper female pipe threads are not commonly used.)
; Longscrew threads: These are parallel pipe threads used where a pressure-tight joint is achieved by the compression of a soft material (such as an o-ring seal or a washer) between the end face of the male thread and a socket or nipple face, with the tightening of a backnut. | 1 | Applied and Interdisciplinary Chemistry |
Biuret was first prepared and studied by Gustav Heinrich Wiedemann (1826–1899) for his doctoral dissertation, which was submitted in 1847. His findings were reported in several articles. | 0 | Theoretical and Fundamental Chemistry |
Real gases can be characterized by their difference from ideal. This is done by writing the mechanical equation of state in the form where , called the compressibility factor, is usually expressed either as a function of pressure and temperature, or density and temperature, and in each case in the limit or , , the ideal gas value.
In the second case . Thus for a van der Waals fluid the compressibility factor is , or in terms of reduced variables
where . At the critical point, , .
In the limit , (for finite ); the fluid behaves like an ideal gas, a point noted several times earlier. Note additionally that the derivative for , and when this is . The slope is positive or negative depending on whether is greater than or less than , and becomes infinitely large negative as approaches .
Figure 6 shows a plot of various isotherms of vs . Also shown are the spinodal and coexistence curves described previously. The subcritical isotherm consists of stable, metastable, and unstable segments, and are identified the same as they were in Fig. 1. Also included are the zero initial slope isotherm and the one corresponding to infinite temperature.
By plotting vs using as a parameter, one obtains the generalized compressibility chart for a vdW gas, which is shown in Fig. 7. Like all other vdW properties, this is not quantitatively correct for most gases but it has the correct qualitative features as can be seen by comparison with this figure which was produced from data using real gases. The two graphs are similar, including the caustic generated by the crossing isotherms; they are qualitatively very much alike. | 0 | Theoretical and Fundamental Chemistry |
The basic setup in electrosynthesis is a galvanic cell, a potentiostat and two electrodes. Typical solvent and electrolyte combinations minimizes electrical resistance. Protic conditions often use alcohol-water or dioxane-water solvent mixtures with an electrolyte such as a soluble salt, acid or base. Aprotic conditions often use an organic solvent such as acetonitrile or dichloromethane with electrolytes such as lithium perchlorate or tetrabutylammonium salts. The choice of electrodes with respect to their composition and surface area can be decisive. For example, in aqueous conditions the competing reactions in the cell are the formation of oxygen at the anode and hydrogen at the cathode. In this case a graphite anode and lead cathode could be used effectively because of their high overpotentials for oxygen and hydrogen formation respectively. Many other materials can be used as electrodes. Other examples include platinum, magnesium, mercury (as a liquid pool in the reactor), stainless steel or reticulated vitreous carbon. Some reactions use a sacrificial electrode that is consumed during the reaction like zinc or lead. Cell designs can be undivided cell or divided cell type. In divided cells the cathode and anode chambers are separated with a semiporous membrane. Common membrane materials include sintered glass, porous porcelain, polytetrafluoroethene or polypropylene. The purpose of the divided cell is to permit the diffusion of ions while restricting the flow of the products and reactants. This separation simplifies workup. An example of a reaction requiring a divided cell is the reduction of nitrobenzene to phenylhydroxylamine, where the latter chemical is susceptible to oxidation at the anode. | 0 | Theoretical and Fundamental Chemistry |
In powder samples there is a tendency for plate- or rod-like crystallites to align themselves along the axis of a cylindrical sample holder. In solid polycrystalline samples the production of the material may result in greater volume fraction of certain crystal orientations (commonly referred to as texture). In such cases the reflex intensities will vary from that predicted for a completely random distribution. Rietveld allowed for moderate cases of the former by introducing a correction factor:
where is the intensity expected for a random sample, is the preferred orientation parameter and is the acute angle between the scattering vector and the normal of the crystallites. | 0 | Theoretical and Fundamental Chemistry |
Photolysis, i.e., photochemical decomposition is a chemical reaction where the compound is broken down by the photons. This decomposition occurs when a photon of sufficient energy encounters a colorant molecule bond with a suitable dissociation energy. The reaction causes homolytic cleavage in the chromophoric system resulting in the fading of the colourant. | 0 | Theoretical and Fundamental Chemistry |
The GDNF family receptor-α (GFRα) proteins are a group of co-receptors which form complexes with GDNF-family ligands (GFLs) to activate RET, the receptor of the GFLs. The GFRα co-receptors include the following:
* GFRα1 – preference for GDNF
* GFRα2 – preference for neurturin
* GFRα3 – preference for artemin
* GFRα4 – preference for persephin
* GFRAL - receptor for GDF15 | 1 | Applied and Interdisciplinary Chemistry |
In adults, the primary metabolic pathway for paracetamol is glucuronidation. This yields a relatively non-toxic metabolite, which is excreted into bile and passed out of the body. A small amount of the drug is metabolized via the cytochrome P-450 pathway (to be specific, CYP3A4 and CYP2E1) into NAPQI, which is extremely toxic to liver tissue, as well as being a strong biochemical oxidizer. In an average adult, only a small amount (approximately 10% of a therapeutic paracetamol dose) of NAPQI is produced, which is inactivated by conjugation with glutathione (GSH). The amount of NAPQI produced differs in certain populations.
The minimum dosage at which paracetamol causes toxicity usually is 7.5 to 10g in the average person. The lethal dose is usually between 10 g and 15 g. Concurrent alcohol intake lowers these thresholds significantly. Chronic alcoholics may be more susceptible to adverse effects due to reduced glutathione levels. Other populations may experience effects at lower or higher dosages depending on differences in P-450 enzyme activity and other factors which affect the amount of NAPQI produced. In general, however, the primary concern is accidental or intentional paracetamol overdose.
When a toxic dose of paracetamol is ingested, the normal glucuronide pathway is saturated and large amounts of NAPQI are produced. Liver reserves of glutathione are depleted by conjugation with this excess NAPQI. The mechanism by which toxicity results is complex, but is believed to involve reaction between unconjugated NAPQI and critical proteins as well as increased susceptibility to oxidative stress caused by the depletion of glutathione. | 1 | Applied and Interdisciplinary Chemistry |
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