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This type of tensiometer uses a platinum ring which is submersed in a liquid. As the ring is pulled out of the liquid, the force required is precisely measured in order to determine the surface tension of the liquid.
The method is well-established as shown by a number of international standards on it such as ASTM D971. This method is widely used for interfacial tension measurement between two liquids but care should be taken to make sure to keep the platinum ring undeformed. | 0 | Theoretical and Fundamental Chemistry |
The Alternative Splicing and Transcript Diversity database (ASTD) was a database of transcript variants maintained by the European Bioinformatics Institute from 2008 to 2012. It contained transcription initiation, polyadenylation and splicing variant data. | 1 | Applied and Interdisciplinary Chemistry |
In alkylimino-de-oxo-bisubstitution, a primary or secondary amine adds to the carbonyl group and a proton is transferred from the nitrogen to the oxygen atom to create a carbinolamine. In the case of a primary amine, a water molecule can be eliminated from the carbinolamine intermediate to yield an imine or its trimer, a hexahydrotriazine This reaction is catalyzed by acid. Hydroxylamine () can also add to the carbonyl group. After the elimination of water, this results in an oxime. An ammonia derivative of the form such as hydrazine () or 2,4-dinitrophenylhydrazine can also be the nucleophile and after the elimination of water, resulting in the formation of a hydrazone, which are usually orange crystalline solids. This reaction forms the basis of a test for aldehydes and ketones. | 0 | Theoretical and Fundamental Chemistry |
The species depends heavily on mesic habitats, and in areas on the periphery of its range, which contain distinctive and divergent subspecies, populations may be lost if the wetness of the habitats changes. A distinct Pleistocene relict subspecies, M. d. chihuahuensis, the Chihuahuan vole, was also found in Chihuahua, Mexico, but has not been recorded since 1988 after its habitat was degraded by recreational activities and especially overgrazing, and eventually the marsh was completely drained by the early 2000s. This subspecies displayed notable divergence from other populations and was highly isolated from any others, and would be considered a distinctive subspecies. In addition, two other populations in New Mexico appear to have been extirpated in recent times, likely as a consequence of climate change-induced drying and overgrazing. Due to the heavy association between meadow voles and mesic habitats, they are especially at risk from drying trends in areas at the peripheries of their range, leaving many of these populations at heavy risk of extirpation. | 1 | Applied and Interdisciplinary Chemistry |
Ozone depletion
A team of researchers at the University of East Anglia analysed unpolluted air samples from Tasmania dating from the period 1978 to 2012. They concluded that the CFC's they studied had started entering the atmosphere from anthropogenic sources in the 1960s and that while the abundance of certain CFCs had decreased, owing to the Montreal Protocol, the abundance of CFC-113a in the atmosphere was still growing. Its source remained uncertain, but production of hydrofluorocarbons in East Asia was suspected by some. Between 2012 and 2017, concentrations of the gas jumped by 40 percent. In 2020, the global mean concentration of CFC-113a was 1.02 ppt with global emissions of 2.5 ± 0.4 ODP-Gg yr. | 1 | Applied and Interdisciplinary Chemistry |
Particulate inorganic carbon (PIC) can be contrasted with dissolved inorganic carbon (DIC), the other form of inorganic carbon found in the ocean. These distinctions are important in chemical oceanography. Particulate inorganic carbon is sometimes called suspended inorganic carbon. In operational terms, it is defined as the inorganic carbon in particulate form that is too large to pass through the filter used to separate dissolved inorganic carbon.
Most PIC is calcium carbonate, CaCO, particularly in the form of calcite, but also in the form of aragonite. Calcium carbonate makes up the shells of many marine organisms. It also forms during whiting events and is excreted by marine fish during osmoregulation. | 0 | Theoretical and Fundamental Chemistry |
The macroscopic theory of van der Waals theory has many experimental validations. Among which, some of the most notable ones are Derjaguin (1960); Derjaguin, Abrikosova and Lifshitz (1956) and Israelachvili and Tabor (1973), who measured the balance of forces between macroscopic bodies of glass, or glass and mica; Haydon and Taylor (1968), who measured the forces across bilayers by measuring their contact angle; and lastly Shih and Parsegian (1975), who investigated Van der Waals potentials between heavy alkali-metal atoms and gold surfaces using atomic-beam-deflection. | 0 | Theoretical and Fundamental Chemistry |
* NADPH-cytochrome P450 reductase
Cytochrome P450 reductase, also known as NADPH:ferrihemoprotein oxidoreductase, NADPH:hemoprotein oxidoreductase, NADPH:P450 oxidoreductase, P450 reductase, POR, CPR, CYPOR, is a membrane-bound enzyme required for electron transfer to cytochrome P450 in the microsome of the eukaryotic cell from a FAD- and FMN-containing enzyme NADPH:cytochrome P450 reductase
The general scheme of electron flow in the POR/P450 system is:
NADPH
FAD
FMN
P450
O
* Reduced (ferrous) cytochrome P450
During reduction reactions, a chemical can enter futile cycling, in which it gains a free-radical electron, then promptly loses it to oxygen (to form a superoxide anion). | 1 | Applied and Interdisciplinary Chemistry |
Pregnancy rate may be defined in various ways. In the United States, SART and the Centers for Disease Control (and appearing in the table in the Success Rates section above) include statistics on positive pregnancy test and clinical pregnancy rate.
The 2019 summary compiled by the SART the following data for non-donor eggs (first embryo transfer) in the United States:
In 2006, Canadian clinics reported an average pregnancy rate of 35%. A French study estimated that 66% of patients starting IVF treatment finally succeed in having a child (40% during the IVF treatment at the centre and 26% after IVF discontinuation). Achievement of having a child after IVF discontinuation was mainly due to adoption (46%) or spontaneous pregnancy (42%). | 1 | Applied and Interdisciplinary Chemistry |
In hydrodynamics, the behavior of flowing liquids is illustrated by flow lines. They run in the same direction as the flow itself. If the outflowing liquid hits an edge, the flow is compressed into a smaller cross-section. It only does not break off if the flow rate of liquid particles remains constant, regardless of where an imaginary cross section (perpendicular to the flow) is located. So the same amount of mass must flow in through one cross-sectional area as flows out of another. One can now conclude from this, but also observe in reality, that the flow accelerates at bottlenecks and the streamlines are bundled. This situation describes the continuity equation for non-turbulent flows. | 1 | Applied and Interdisciplinary Chemistry |
Surprisal analysis was formulated at the Hebrew University of Jerusalem as a joint effort between Raphael David Levine, Richard Barry Bernstein and Avinoam Ben-Shaul in 1972. Levine and colleagues had recognized a need to better understand the dynamics of non-equilibrium systems, particularly of small systems, that are not seemingly applicable to thermodynamic reasoning. Alhassid and Levine first applied surprisal analysis in nuclear physics, to characterize the distribution of products in heavy ion reactions. Since its formulation, surprisal analysis has become a critical tool for the analysis of reaction dynamics and is an official IUPAC term.* | 0 | Theoretical and Fundamental Chemistry |
Valves stop (or regulate) the flow of liquids or gases. They are categorized by application, such as isolation, throttling, and non-return.
Isolation valves temporarily disconnect part of a piping system to allow maintenance or repair, for example. Isolation valves are typically left in either a fully open or closed position. A given isolation valve may be in place for many years without being operated but must be designed to be readily operable whenever needed, including for emergency use.
Throttling valves control the amount or pressure of a fluid allowed to pass through and are designed to withstand the stress and wear caused by this operation. Because they may wear out in this usage, they are often installed alongside isolation valves which can temporarily disconnect a failing throttling valve from the rest of the system, so it can be refurbished or replaced.
Non-return or check valves allow the free flow of a fluid in one direction but prevent its flow in a reverse direction. They are often seen in drainage or sewage systems but may also be used in pressurized systems.
Valves are available in several types, based on design and purpose:
*Gate, plug, or ball valves – Isolation
*Globe valve – Throttling
*Needle valve – Throttling, usually with high precision but low flow
*Butterfly or diaphragm valves – Isolation and throttling
*Check valve – Preventing reverse flow (non-return) | 1 | Applied and Interdisciplinary Chemistry |
A line source is a line from which fluid appears and flows away on planes perpendicular to the line. When we consider 2-D flows on the perpendicular plane, a line source appears as a point source.
By symmetry, we can assume that the fluid flows radially outward from the source.
The strength of a source can be given by the volume flow rate that it generates. | 1 | Applied and Interdisciplinary Chemistry |
Mefloquine, sold under the brand name Lariam among others, is a medication used to prevent or treat malaria. When used for prevention it is typically started before potential exposure and continued for several weeks after potential exposure. It can be used to treat mild or moderate malaria but is not recommended for severe malaria. It is taken by mouth.
Common side effects include vomiting, diarrhea, headaches, sleep disorders, and a rash. Serious side effects include potentially long-term mental health problems such as depression, hallucinations, and anxiety and neurological side effects such as poor balance, seizures, and ringing in the ears. It is therefore not recommended in people with a history of mental health problems or epilepsy. It appears to be safe during pregnancy and breastfeeding.
Mefloquine was developed by the United States Army in the 1970s and came into use in the mid-1980s. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. | 0 | Theoretical and Fundamental Chemistry |
Rare-earth oxides such as ytterbium oxide (YbO) and erbium oxide (ErO) are the most commonly used selective emitters. These oxides emit a narrow band of wavelengths in the near-infrared region, allowing the emission spectra to be tailored to better fit the absorbance characteristics of a particular PV material. The peak of the emission spectrum occurs at 1.29 eV for YbO and 0.827 eV for ErO. As a result, YbO can be used a selective emitter for silicon cells and ErO, for GaSb or InGaAs. However, the slight mismatch between the emission peaks and band gap of the absorber costs significant efficiency. Selective emission only becomes significant at 1100 °C and increases with temperature. Below 1700 °C, selective emission of rare-earth oxides is fairly low, further decreasing efficiency. Currently, 13% efficiency has been achieved with YbO and silicon PV cells. In general selective emitters have had limited success. More often filters are used with black body emitters to pass wavelengths matched to the bandgap of the PV and reflect mismatched wavelengths back to the emitter. | 0 | Theoretical and Fundamental Chemistry |
Syntactic foams are composite materials synthesized by filling a metal, polymer, cementitious or ceramic matrix with hollow spheres called microballoons or cenospheres or non-hollow spheres (e.g. perlite) as aggregates. In this context, "syntactic" means "put together." The presence of hollow particles results in lower density, higher specific strength (strength divided by density), lower coefficient of thermal expansion, and, in some cases, radar or sonar transparency. | 0 | Theoretical and Fundamental Chemistry |
The simplest derivation of the Avrami equation makes a number of significant assumptions and simplifications:
* Nucleation occurs randomly and homogeneously over the entire untransformed portion of the material.
* The growth rate does not depend on the extent of transformation.
* Growth occurs at the same rate in all directions.
If these conditions are met, then a transformation of into will proceed by the nucleation of new particles at a rate per unit volume, which grow at a rate into spherical particles and only stop growing when they impinge upon each other. During a time interval , nucleation and growth can only take place in untransformed material. However, the problem is more easily solved by applying the concept of an extended volume – the volume of the new phase that would form if the entire sample was still untransformed. During the time interval to the number of nuclei N that appear in a sample of volume V will be given by
where is one of two parameters in this simple model: the nucleation rate per unit volume, which is assumed to be constant. Since growth is isotropic, constant and unhindered by previously transformed material, each nucleus will grow into a sphere of radius , and so the extended volume of due to nuclei appearing in the time interval will be
where is the second of the two parameters in this simple model: the growth velocity of a crystal, which is also assumed constant. The integration of this equation between and will yield the total extended volume that appears in the time interval:
Only a fraction of this extended volume is real; some portion of it lies on previously transformed material and is virtual. Since nucleation occurs randomly, the fraction of the extended volume that forms during each time increment that is real will be proportional to the volume fraction of untransformed . Thus
rearranged
and upon integration:
where Y is the volume fraction of ().
Given the previous equations, this can be reduced to the more familiar form of the Avrami (JMAK) equation, which gives the fraction of transformed material after a hold time at a given temperature:
where , and .
This can be rewritten as
which allows the determination of the constants n and k from a plot of vs . If the transformation follows the Avrami equation, this yields a straight line with slope n and intercept . | 0 | Theoretical and Fundamental Chemistry |
According to Jose Carlos Melo, who is considered to be the "father" of condominial sewers in Brazil, some important constraints for the application of simplified sewerage are:
* Lack of information on fundamentals and techniques of the approach or lack of experience in its application,
* Resistance to change: Institutional, technical and operational changes required by the service provider for implementing the condominial approach usually provoke resistance and can hinder the application.
* Normative and legal restrictions: Existing conservative design and construction standards linked to conventional systems can be an essential constraint in the introduction and dissemination of the systems.
Over the last years, countries like Bolivia and Peru reviewed and modernized technical standards according to methods and criteria established and accepted in Brazil in the 1980s, thus overcoming the latter constraint. | 1 | Applied and Interdisciplinary Chemistry |
The idealized plug flow reactor is an open system resembling a tube with no mixing in the direction of flow but perfect mixing perpendicular to the direction of flow, often used for systems like rivers and water pipes if the flow is turbulent. When a mass balance is made for a tube, one first considers an infinitesimal part of the tube and make a mass balance over that using the ideal tank reactor model. That mass balance is then integrated over the entire reactor volume to obtain:
In numeric solutions, e.g. when using computers, the ideal tube is often translated to a series of tank reactors, as it can be shown that a PFR is equivalent to an infinite number of stirred tanks in series, but the latter is often easier to analyze, especially at steady state. | 1 | Applied and Interdisciplinary Chemistry |
Choi studied piano at Yewon Middle School, Korea's first middle school dedicated to the arts. In high school, Choi liked Chemistry and Physics classes tremendously and decided to become a scientist. Choi attended college at Seoul National University in South Korea, earning her B.S. (major in Food and Nutrition and minor in Chemistry) in 1993 and M.S. in 1995. She worked with Jin-Ho Choy on the crystal structure, pressure-induced phase transitions, and magnetism of chromium-niobium oxide materials that adopt the double perovskite structure.
For her doctoral study, Choi came to the United States in 1995. She worked at Michigan State University in the laboratory of Mercouri G. Kanatzidis, earning her Ph.D. in chemistry in 2000. Her graduate work focused on the synthesis of various solid state antimony and bismuth-containing chalcogenides using the "molten polychalcogenide salt method."
Choi then conducted postdoctoral studies from 2000 to 2002 at the University of California, Santa Barbara with Galen D. Stucky and Eric W. McFarland. Her postdoctoral research concerned the electrochemical synthesis of nanostructured thin films. | 0 | Theoretical and Fundamental Chemistry |
Industrially, the main methods for producing nitriles are ammoxidation and hydrocyanation. Both routes are green in the sense that they do not generate stoichiometric amounts of salts. | 0 | Theoretical and Fundamental Chemistry |
Many viruses undergo frequent mutations that result in changes in amino acid composition of their important proteins. Epitopes located on the protein may also undergo alterations in the process. Such an altered epitope binds less strongly with the antibodies specific to the unaltered epitope that would have stimulated the immune system. This is unfortunate because somatic hypermutation does give rise to clones capable of producing soluble antibodies that would have bound the altered epitope avidly enough to neutralize it. But these clones would consist of naive cells which are not allowed to proliferate by the weakly binding antibodies produced by the priorly stimulated clone. This doctrine is known as the original antigenic sin. This phenomenon comes into play particularly in immune responses against influenza, dengue and HIV viruses. This limitation, however, is not imposed by the phenomenon of polyclonal response, but rather, against it by an immune response that is biased in favor of experienced memory cells against the "novice" naive cells. | 1 | Applied and Interdisciplinary Chemistry |
A union also connects two pipes but is quite different from a coupling, as it allows future disconnection of the pipes for maintenance. In contrast to a coupling requiring solvent welding, soldering, or rotation (for threaded couplings), a union allows easy connection and disconnection multiple times if needed. It consists of three parts: a nut, a female, and a male end. When the female and male ends are joined, the nut seals the joint by pressing the two ends tightly together. Unions are a type of very compact flange connector.
Dielectric unions, with dielectric insulation, separate dissimilar metals (such as copper and galvanized steel) to prevent galvanic corrosion. When two dissimilar metals are in contact with an electrically conductive solution (ordinary tap water is conductive), they form an electrochemical couple which generates a voltage by electrolysis. When the metals are in direct contact with each other, the electric current from one to the other also moves metallic ions from one to the other; this dissolves one metal, depositing it on the other. A dielectric union breaks the electrical path with a plastic liner between its halves, limiting galvanic corrosion.
Rotary unions allow mechanical rotation of one of the joined parts while resisting leakage. | 1 | Applied and Interdisciplinary Chemistry |
Sir Humphry Davy, 1st Baronet, (17 December 177829 May 1829) was a British chemist and inventor who invented the Davy lamp and a very early form of arc lamp. He is also remembered for isolating, by using electricity, several elements for the first time: potassium and sodium in 1807 and calcium, strontium, barium, magnesium and boron the following year, as well as for discovering the elemental nature of chlorine and iodine. Davy also studied the forces involved in these separations, inventing the new field of electrochemistry. Davy is also credited with discovering clathrate hydrates.
In 1799, he experimented with nitrous oxide and was astonished at how it made him laugh. He nicknamed it "laughing gas" and wrote about its potential as an anaesthetic to relieve pain during surgery.
Davy was a baronet, President of the Royal Society (PRS), Member of the Royal Irish Academy (MRIA), Fellow of the Geological Society (FGS), and a member of the American Philosophical Society (elected 1810). Berzelius called Davys 1806 Bakerian Lecture On Some Chemical Agencies of Electricity' "one of the best memoirs which has ever enriched the theory of chemistry." | 1 | Applied and Interdisciplinary Chemistry |
In the Calvin cycle, DHAP is one of the products of the sixfold reduction of 1,3-bisphosphoglycerate by NADPH. It is also used in the synthesis of sedoheptulose 1,7-bisphosphate and fructose 1,6-bisphosphate, both of which are used to reform ribulose 5-phosphate, the key carbohydrate of the Calvin cycle.
DHAP is also the product of the dehydrogenation of -glycerol-3-phosphate, which is part of the entry of glycerol (sourced from triglycerides) into the glycolytic pathway. Conversely, reduction of glycolysis-derived DHAP to -glycerol-3-phosphate provides adipose cells with the activated glycerol backbone they require to synthesize new triglycerides. Both reactions are catalyzed by the enzyme glycerol 3-phosphate dehydrogenase with NAD/NADH as cofactor.
DHAP also has a role in the ether-lipid biosynthesis process in the protozoan parasite Leishmania mexicana.
DHAP is a precursor to 2-oxopropanal. This conversion is the basis of a potential biotechnological route to the commodity chemical 1,2-propanediol. | 0 | Theoretical and Fundamental Chemistry |
Governments have set standards on the allowable turbidity in drinking water. In the United States, public water systems that use conventional or direct filtration methods must not have a turbidity higher than 1.0 NTU at the plant outlet and all samples for turbidity must be less than or equal to 0.3 NTU for at least 95 percent of the samples in any month. Systems that use filtration other than the conventional or direct filtration must follow state limits, which must include turbidity at no time exceeding 5 NTU. Many drinking water utilities strive to achieve levels as low as 0.1 NTU. The European turbidity standard is 4 NTU. | 0 | Theoretical and Fundamental Chemistry |
Chairman, Gordon Research Conference on Analytical Chemistry; James B. Himes Merit Award of the Chicago Chromatography Discussion Group; M.S. Tswett Award and Medal in Chromatography; American Chemical Society Award in Chromatography; ISCO Award in Biochemical Instrumentation; Eastern Analytical Symposium Award in Chromatography; Chemical Instrumentation Award of the American Chemical Society; Distinguished Faculty Research Lecture, Indiana University. | 0 | Theoretical and Fundamental Chemistry |
In 1885, Auer von Welsbach used a method of fractional crystallization that he had developed himself to separate the alloy didymium into its two parts, for the first time. It had previously been believed to be an element. After 167 crystallizations, Auer von Welsbach differentiated it into two colored salts: he named the green colored salt "praseodymium" and the pink one "neodidymium".
He announced his achievement to the Vienna Academy of Sciences on 18 June 1885. His achievement was approved by Bunsen, but met with considerable skepticism from others.
The name "neodidymium" is derived from the Greek words neos (νέος), new, and didymos (διδύμος), twin. The name praseodymium comes from the Greek prasinos (πράσινος), meaning "green". In naming both elements, and not leaving the original name didymium to the more-abundant component, Auer von Welsbach diverged from established practice, which was to give a new name only to the less-abundant component. Nonetheless, his name for the major fraction, neodidymium, after some modification, became the name of the element neodymium. Praseodymium was also accepted as the name of the minor fraction. | 1 | Applied and Interdisciplinary Chemistry |
The development process is modeled as the development of gene expression states. The gene expression pattern at time is defined as the initial expression state. The interactions among genes change the expression states during the development process. This process is modeled by the following differential equations
where τ) represents the expression state of at time . It is determined by a filter function σ. represents the weighted sum of regulatory effects () of all genes on gene at time . In the original Wagner model, the filter function is a step function
In other variants, the filter function is implemented as a sigmoidal function
In this way, the expression states will acquire a continuous distribution. The gene expression will reach the final state if it reaches a stable pattern. | 1 | Applied and Interdisciplinary Chemistry |
Systematic pairwise deletion of genes or inhibition of gene expression can be used to identify genes with related function, even if they do not interact physically. Epistasis refers to the fact that effects for two different gene knockouts may not be additive; that is, the phenotype that results when two genes are inhibited may be different from the sum of the effects of single knockouts. | 1 | Applied and Interdisciplinary Chemistry |
An immobilized enzyme is an enzyme, with restricted mobility, attached to an inert, insoluble material—such as calcium alginate (produced by reacting a mixture of sodium alginate solution and enzyme solution with calcium chloride). This can provide increased resistance to changes in conditions such as pH or temperature. It also lets enzymes be held in place throughout the reaction, following which they are easily separated from the products and may be used again - a far more efficient process and so is widely used in industry for enzyme catalysed reactions. An alternative to enzyme immobilization is whole cell immobilization. Immobilized enzymes are easily to be handled, simply separated from their products, and can be reused.
Enzymes are bio-catalysts which play an essential role in the enhancement of chemical reactions in cells without being persistently modified, wasted, nor resulting in the loss of equilibrium of chemical reactions. Although the characteristics of enzymes are extremely unique, their utility in the industry is limited due to the lack of re-usability, stability, and high-cost of production. | 0 | Theoretical and Fundamental Chemistry |
Succinate-Q oxidoreductase, also known as complex II or succinate dehydrogenase, is a second entry point to the electron transport chain. It is unusual because it is the only enzyme that is part of both the citric acid cycle and the electron transport chain. Complex II consists of four protein subunits and contains a bound flavin adenine dinucleotide (FAD) cofactor, iron–sulfur clusters, and a heme group that does not participate in electron transfer to coenzyme Q, but is believed to be important in decreasing production of reactive oxygen species. It oxidizes succinate to fumarate and reduces ubiquinone. As this reaction releases less energy than the oxidation of NADH, complex II does not transport protons across the membrane and does not contribute to the proton gradient.
In some eukaryotes, such as the parasitic worm Ascaris suum, an enzyme similar to complex II, fumarate reductase (menaquinol:fumarate
oxidoreductase, or QFR), operates in reverse to oxidize ubiquinol and reduce fumarate. This allows the worm to survive in the anaerobic environment of the large intestine, carrying out anaerobic oxidative phosphorylation with fumarate as the electron acceptor. Another unconventional function of complex II is seen in the malaria parasite Plasmodium falciparum. Here, the reversed action of complex II as an oxidase is important in regenerating ubiquinol, which the parasite uses in an unusual form of pyrimidine biosynthesis. | 1 | Applied and Interdisciplinary Chemistry |
There are >50 human diseases associated with SINEs. When inserted near or within the exon, SINEs can cause improper splicing, become coding regions, or change the reading frame, often leading to disease phenotypes in humans and other animals. Insertion of Alu elements in the human genome is associated with breast cancer, colon cancer, leukemia, hemophilia, Dent's disease, cystic fibrosis, neurofibromatosis, and many others. | 1 | Applied and Interdisciplinary Chemistry |
The TRAFAC class of G domain proteins is named after the prototypical member, the translation factor G proteins. They play roles in translation, signal transduction, and cell motility. | 1 | Applied and Interdisciplinary Chemistry |
Japan was the first country that allowed the use of sucrose esters as food additives. The Japanese Ministry of Health and Welfare approved sucrose esters in 1959. Then, in 1969, FAO/WHO approved the use of sucrose esters.
Sucrose esters were approved and registered by European Food Safety Authority or EFSA under the E number of E 473.
In the US, sucrose esters were approved by the FDA (Food and Drug Administration). | 0 | Theoretical and Fundamental Chemistry |
The discovery of TOR and mTOR stemmed from independent studies of the natural product rapamycin by Joseph Heitman, Rao Movva, and Michael N. Hall in 1991; by David M. Sabatini, Hediye Erdjument-Bromage, Mary Lui, Paul Tempst, and Solomon H. Snyder in 1994; and by Candace J. Sabers, Mary M. Martin, Gregory J. Brunn, Josie M. Williams, Francis J. Dumont, Gregory Wiederrecht, and Robert T. Abraham in 1995. In 1991, working in yeast, Hall and colleagues identified the TOR1 and TOR2 genes. In 1993, Robert Cafferkey, George Livi, and colleagues, and Jeannette Kunz, Michael N. Hall, and colleagues independently cloned genes that mediate the toxicity of rapamycin in fungi, known as the TOR/DRR genes. However, the molecular target of the FKBP12-rapamycin complex in mammals was not known. In 1994, researchers working in the labs of Stuart L. Schreiber, Solomon H. Snyder and Robert T. Abraham independently discovered a protein that directly interacts with FKBP12-rapamycin, which became known as mTOR due to its homology to the yeast TOR/DRR genes.
Rapamycin arrests fungal activity at the G1 phase of the cell cycle. In mammals, it suppresses the immune system by blocking the G1 to S phase transition in T-lymphocytes. Thus, it is used as an immunosuppressant following organ transplantation. Interest in rapamycin was renewed following the discovery of the structurally related immunosuppressive natural product FK506 in 1987. In 1989–90, FK506 and rapamycin were determined to inhibit T-cell receptor (TCR) and IL-2 receptor signaling pathways, respectively. The two natural products were used to discover the FK506- and rapamycin-binding proteins, including FKBP12, and to provide evidence that FKBP12–FK506 and FKBP12–rapamycin might act through gain-of-function mechanisms that target distinct cellular functions. These investigations included key studies by Francis Dumont and Nolan Sigal at Merck contributing to show that FK506 and rapamycin behave as reciprocal antagonists. These studies implicated FKBP12 as a possible target of rapamycin, but suggested that the complex might interact with another element of the mechanistic cascade.
In 1991, calcineurin was identified as the target of FKBP12-FK506. That of FKBP12-rapamycin remained mysterious until genetic and molecular studies in yeast established FKBP12 as the target of rapamycin, and implicated TOR1 and TOR2 as the targets of FKBP12-rapamycin in 1991 and 1993, followed by studies in 1994 when several groups, working independently, discovered the mTOR kinase as its direct target in mammalian tissues. Sequence analysis of mTOR revealed it to be the direct ortholog of proteins encoded by the yeast target of rapamycin 1 and 2 (TOR1 and TOR2) genes, which Joseph Heitman, Rao Movva, and Michael N. Hall had identified in August 1991 and May 1993. Independently, George Livi and colleagues later reported the same genes, which they called dominant rapamycin resistance 1 and 2 (DRR1 and DRR2), in studies published in October 1993.
The protein, now called mTOR, was originally named FRAP by Stuart L. Schreiber and RAFT1 by David M. Sabatini; FRAP1 was used as its official gene symbol in humans. Because of these different names, mTOR, which had been first used by Robert T. Abraham, was increasingly adopted by the community of scientists working on the mTOR pathway to refer to the protein and in homage to the original discovery of the TOR protein in yeast that was named TOR, the Target of Rapamycin, by Joe Heitman, Rao Movva, and Mike Hall. TOR was originally discovered at the Biozentrum and Sandoz Pharmaceuticals in 1991 in Basel, Switzerland, and the name TOR pays further homage to this discovery, as TOR means doorway or gate in German, and the city of Basel was once ringed by a wall punctuated with gates into the city, including the iconic Spalentor. "mTOR" initially meant "mammalian target of rapamycin", but the meaning of the "m" was later changed to "mechanistic". Similarly, with subsequent discoveries the zebra fish TOR was named zTOR, the Arabidopsis thaliana TOR was named AtTOR, and the Drosophila TOR was named dTOR. In 2009 the FRAP1 gene name was officially changed by the HUGO Gene Nomenclature Committee (HGNC) to mTOR, which stands for mechanistic target of rapamycin.
The discovery of TOR and the subsequent identification of mTOR opened the door to the molecular and physiological study of what is now called the mTOR pathway and had a catalytic effect on the growth of the field of chemical biology, where small molecules are used as probes of biology. | 1 | Applied and Interdisciplinary Chemistry |
Further investigations by Sir Edward Abraham and Guy Newton were made in England and isolation of culture fluids from the Sardinian fungus yielded cephalosporin P, N and C. These natural compounds were not found to be potent enough to use as antimicrobial agents but with chemical methods and removal of the natural side chain it was possible to produce 7-aminocephalosporanic acid (7-ACA) which could be further fit with unnatural side chains. 7-ACA is analogous to 6-aminopenicillanic acid (6-APA), a starting block for making several derivatives of penicillins.
In 1959 Abraham reported that his N-phenylacetyl derivative of cephalosporin C was much more potent against Staphylococcus aureus strains than the parent compound. This derivative was later named Cephaloram, a cephalosporin analogue of benzylpenicillin.
Eli Lilly developed a method for producing 7-ACA based on cleaving the α-aminoadipoyl side chain of cephalosporin C. Further work by Robert Morin led to semisynthesis of 3-deacetoxy-7-ACA (7-ADCA) from penicillins which is convenient because penicillins can be fermented with more ease than cephalosporins. For example, 7-ADCA can be semisynthesized in seven chemical reaction steps from phenoxymethylpenicillin. | 1 | Applied and Interdisciplinary Chemistry |
The Prilezhaev reaction involves the conversion of an alkene to an epoxide using a peracid as the oxidant and was first reported in 1909. The reaction has been used as the final step of the synthesis of scopine, a tropane alkaloid. In this approach, a [4+3] cycloaddition mediated by diiron nonacarbonyl is used to construct the bicyclic skeleton, the hydroxyl functional group is then introduced by diastereoselective reduction of the ketone with diisobutylaluminum hydride, and the preparation completed with a Prilezhaev trifluoroperacetic acid epoxidation.
The high reactivity of trifluoroperacetic acid relative to other peroxy acids allows it to successfully oxidize relatively electron-poor alkenes such as 1-hexene and α,β-unsaturated esters such as methyl methacrylate, substrates that are generally resistant to peroxy-acid epoxidation. Including additional buffered trifluoroacetic acid in the mixture gives a vicinal hydroxy–trifluoroacetate structure instead of an epoxide, which can be converted to the diol by treatment with acidic methanol, such as in the following conversion of 1-dodecene to 1,2-dodecanediol.
In the case of an allyl alcohol compound with a proximate carbonyl functional group, the epoxide can undergo a ring-expansion reaction to form a dioxolane. The process below was used as part of the total synthesis of neosporol, a natural product:
The preparation of the isomeric compound sporol involved a similar dioxolane formation. In this case, the use of trifluoroperacetic acid derived from hydrogen peroxide, which therefore presumably contained traces of water, gave mostly a hemiacetal rather than the closed-ring dioxolane. The use of the urea complex, which gave a water-free material, successfully gave the dioxolane as the major product. The dioxolane is expanded to the 1,3-dioxane system found in sporol at a later step in the synthesis. | 0 | Theoretical and Fundamental Chemistry |
The following packages calculate the state of the carbonate system in seawater (including pH):
* [http://cdiac.ornl.gov/oceans/co2rprt.html CO2SYS] , available as a stand-alone executable, Excel spreadsheet, or MATLAB script.
* [http://cran.at.r-project.org/web/packages/seacarb/index.html seacarb], a R package for Windows, Mac OS X and Linux (also available [https://web.archive.org/web/20060212225505/http://www.obs-vlfr.fr/%7Egattuso/seacarb.php here])
* [http://www.soest.hawaii.edu/oceanography/faculty/zeebe_files/CO2_System_in_Seawater/csys.html CSYS], a Matlab script | 0 | Theoretical and Fundamental Chemistry |
Many alloys of industrial significance have some volume fraction of second phase particles, either as a result of impurities or from deliberate alloying additions. Depending on their size and distribution such particles may act to either encourage or retard recrystallization. | 1 | Applied and Interdisciplinary Chemistry |
Lipinski's rule states that, in general, an orally active drug has no more than one violation of the following criteria:
* No more than 5 hydrogen bond donors (the total number of nitrogen–hydrogen and oxygen–hydrogen bonds)
* No more than 10 hydrogen bond acceptors (all nitrogen or oxygen atoms)
* A molecular mass less than 500 daltons
* A calculated octanol-water partition coefficient (Clog P) that does not exceed 5
Note that all numbers are multiples of five, which is the origin of the rule's name.
As with many other rules of thumb, such as Baldwins rules for ring closure, there are many exceptions'. | 1 | Applied and Interdisciplinary Chemistry |
MAO inhibitors within 14 days. MAO inhibitors include isocarboxazid, linezolid, phenelzine, rasagiline, selegiline, and tranylcypromine.
Drinking alcohol can increase side effects of dexbrompheniramine. | 0 | Theoretical and Fundamental Chemistry |
Alongside the ACC there is also the associated Meridional Overturning Circulation (MOC), which is also mainly driven by wind forcing. The insensitivity of the mean current to the accelerating wind forcing can also be seen in the MOC. This near independence of the MOC to the increase of wind stress is referred to as eddy compensation. There would be perfect eddy compensation when the Ekman transport would be balanced by eddy-induced transport.
There is a widespread belief that the sensitivities of the transport in the ACC and MOC are dynamically linked. However, note that eddy saturation and eddy compensation are distinct dynamical mechanisms. Occurrence of one does not necessarily entail the occurrence of the other. It is hypothesized that dearth of a dynamical link between eddy saturation and eddy compensation is a consequence of the depth dependence (cancellation between the Eulerian circulation and eddy-induced circulation). Currently it is assumed that the ACC is fully eddy saturated, but only partially eddy compensated. The degree to which there is eddy compensation in the Southern Ocean is currently unknown. | 1 | Applied and Interdisciplinary Chemistry |
6-Methylisoxanthopterin (6MI) is a base analog for the nucleotide guanine. It is useful as a fluorescent indicator because unlike most other base analogs, quenching does not occur when it is incorporated into a double helix. In fact, it exhibits a 3 to 4-fold increase in quantum yield when it is incorporated into a duplex formation. This allows 6MI to be used to probe the dynamics of DNA or RNA helices using a technique such as fluorescence polarization anisotropy. | 1 | Applied and Interdisciplinary Chemistry |
The placeholder R is often used as a generic placeholder for alkyl (saturated hydrocarbon) group side chains in chemical structure diagrams. To indicate other non-carbon groups in structure diagrams, X, Y, or Z are often used. | 0 | Theoretical and Fundamental Chemistry |
Agmatine biosynthesis by arginine decarboxylation is well-positioned to compete with the principal arginine-dependent pathways, namely: nitrogen metabolism (urea cycle), and polyamine and nitric oxide (NO) synthesis (see illustration Agmatine Metabolic Pathways). Agmatine degradation occurs mainly by hydrolysis, catalyzed by agmatinase into urea and putrescine, the diamine precursor of polyamine biosynthesis. An alternative pathway, mainly in peripheral tissues, is by diamine oxidase-catalyzed oxidation into agmatine-aldehyde, which is in turn converted by aldehyde dehydrogenase into guanidinobutyrate and secreted by the kidneys. | 1 | Applied and Interdisciplinary Chemistry |
However, the biological effects of radiation due to radioactive substances were less easy to gauge. This gave the opportunity for many physicians and corporations to market radioactive substances as patent medicines. Examples were radium enema treatments, and radium-containing waters to be drunk as tonics. Marie Curie protested against this sort of treatment, warning that "radium is dangerous in untrained hands". Curie later died from aplastic anaemia, likely caused by exposure to ionizing radiation. By the 1930s, after a number of cases of bone necrosis and death of radium treatment enthusiasts, radium-containing medicinal products had been largely removed from the market (radioactive quackery). | 0 | Theoretical and Fundamental Chemistry |
For many years, the origin of residual supercoiling in eukaryotic genomes remained unclear. This topological puzzle was referred to by some as the "linking number paradox". However, when experimentally determined structures of the nucleosome displayed an over-twisted left-handed wrap of DNA around the histone octamer, this paradox was considered to be solved by the scientific community. | 0 | Theoretical and Fundamental Chemistry |
Reductions with metal alkoxyaluminium hydrides are chemical reactions that involve either the net hydrogenation of an unsaturated compound or the replacement of a reducible functional group with hydrogen by metal alkoxyaluminium hydride reagents. | 0 | Theoretical and Fundamental Chemistry |
Fahy is the world's foremost expert in organ cryopreservation by vitrification. Fahy introduced the modern successful approach to vitrification for cryopreservation in cryobiology and he is widely credited, along with William F. Rall, for introducing vitrification into the field of reproductive biology.
In 2005, where he was a keynote speaker at the annual Society for Cryobiology meeting, Fahy announced that Twenty-First Century Medicine had successfully cryopreserved a rabbit kidney at −130 °C by vitrification and transplanted it into a rabbit after rewarming, with subsequent long-term life support by the vitrified-rewarmed kidney as the sole kidney. This research breakthrough was later published in the peer-reviewed journal Organogenesis.
Fahy is also a biogerontologist and is the originator and Editor-in-Chief of The Future of Aging: Pathways to Human Life Extension, a multi-authored book on the future of biogerontology. He currently serves on the editorial boards of Rejuvenation Research and the Open Geriatric Medicine Journal and served for 16 years as a Director of the American Aging Association and for 6 years as the editor of AGE News, the organization's newsletter. | 1 | Applied and Interdisciplinary Chemistry |
The Phillips catalyst is prepared by impregnating high surface area silica gel with chromium trioxide or related chromium compounds. The solid precatalyst is then calcined in air to give the active catalyst. Only a fraction of the chromium is catalytically active, a fact that interferes with elucidation of the catalytic mechanism. The active catalyst is often depicted as a chromate ester bound to the silica surface. The mechanism for the polymerization process is the subject of much research, the central question being the structure of the active species, which is assumed to be an organochromium compound. Robert L. Banks and J. Paul Hogan, both at Phillips Petroleum, filed the first patents on the Phillips catalyst in 1953. Four years later, the process was commercialized. | 0 | Theoretical and Fundamental Chemistry |
The DNA or RNA aptamers are fixed on the interrogating electrode, where a redox reaction is reported by a redox tag. Gold is often used as the probe surface for interrogating electrodes. The surface of the gold electrode is packed with redox-tagged DNA or RNA aptamers. The redox reporter is often methylene blue. Upon target binding, the aptamer changes structure by folding, bringing the redox reporter closer to the gold electrode. This increase in proximity from the redox-reporter to the electrode enables faster electron transfer from the redox tag to the gold electrode. The increase in speed of electron transfer contributes to a change in Faradaic current that is detected by the potentiostat.
The reference electrode is the site of a known chemical reaction that has a known redox potential. For example, a reference electrode that harbors the reaction of silver-silver chloride (Ag/AgCl) has a fixed redox potential and is the measuring point for the redox potential of the interrogating electrode. The counter electrode (or auxiliary electrode) acts as a cathode or anode to the interrogating electrode. The applied voltage is not passed through the reference electrode due to an impedance supplied by the potentiostat. Therefore, the potential generated within the electrochemical cell is attributed to the interrogating electrode. Current is measured as potential of the interrogating electrode vs. the fixed potential of the reference electrode. The difference in potential is what produces the current in the external circuit and generates a signal. The signal quantifies target binding depending on electron transfer that is stoichimetrically proportional to target binding.
Four electrode method has also been demonstrated in an electrochemical nanoporous alumina membrane sensor, where the aptamer was grafted onto the membrane and not on the electrode. The binding of the aptamer with the target protein produces a change in impedance of the membrane which is picked up by the electrochemical sensor using an impedance spectroscopy analyzer. This approach could be beneficial in cases where the electric field of the electrode can change the aptamer structure or the biointerface which may decrease the sensing ability. | 0 | Theoretical and Fundamental Chemistry |
António Egas Moniz searched for a radiocontrast agent for cerebral angiography. After experiments on rabbits and dogs he settled upon sodium iodide as the best medium. | 0 | Theoretical and Fundamental Chemistry |
Due to historic activities typically related to the radium industry, uranium mining, and military programs, numerous sites contain or are contaminated with radioactivity. In the United States alone, the Department of Energy states there are "millions of gallons of radioactive waste" as well as "thousands of tons of spent nuclear fuel and material" and also "huge quantities of contaminated soil and water." Despite copious quantities of waste, the DOE has stated a goal of cleaning all presently contaminated sites successfully by 2025. The Fernald, Ohio site for example had "31 million pounds of uranium product", "2.5 billion pounds of waste", "2.75 million cubic yards of contaminated soil and debris", and a "223 acre portion of the underlying Great Miami Aquifer had uranium levels above drinking standards." The United States has at least 108 sites designated as areas that are contaminated and unusable, sometimes many thousands of acres. DOE wishes to clean or mitigate many or all by 2025, using the recently developed method of geomelting, however the task can be difficult and it acknowledges that some may never be completely remediated. In just one of these 108 larger designations, Oak Ridge National Laboratory, there were for example at least "167 known contaminant release sites" in one of the three subdivisions of the site. Some of the U.S. sites were smaller in nature, however, cleanup issues were simpler to address, and DOE has successfully completed cleanup, or at least closure, of several sites. | 0 | Theoretical and Fundamental Chemistry |
He is also the co-author of three popular books on total synthesis:
#Classics in Total Synthesis I, 1996
#Classics in Total Synthesis II, 2003
#Classics in Total Synthesis III, 2011
Additionally, he authored or co-authored several other books:
#Molecules That Changed the World, 2008
#Handbook of Combinatorial Chemistry: Drugs, Catalysts, Materials, 2002
#Selenium in Natural Products Synthesis, 1984 | 0 | Theoretical and Fundamental Chemistry |
The unicellular cyanobacterium Synechocystis sp. PCC6803 was the third prokaryote and first photosynthetic organism whose genome was completely sequenced. It continues to be an important model organism. Cyanothece ATCC 51142 is an important diazotrophic model organism. The smallest genomes have been found in Prochlorococcus spp. (1.7 Mb) and the largest in Nostoc punctiforme (9 Mb). Those of Calothrix spp. are estimated at 12–15 Mb, as large as yeast.
Recent research has suggested the potential application of cyanobacteria to the generation of renewable energy by directly converting sunlight into electricity. Internal photosynthetic pathways can be coupled to chemical mediators that transfer electrons to external electrodes. In the shorter term, efforts are underway to commercialize algae-based fuels such as diesel, gasoline, and jet fuel. Cyanobacteria have been also engineered to produce ethanol and experiments have shown that when one or two CBB genes are being over expressed, the yield can be even higher.
Cyanobacteria may possess the ability to produce substances that could one day serve as anti-inflammatory agents and combat bacterial infections in humans. Cyanobacteria's photosynthetic output of sugar and oxygen has been demonstrated to have therapeutic value in rats with heart attacks. While cyanobacteria can naturally produce various secondary metabolites, they can serve as advantageous hosts for plant-derived metabolites production owing to biotechnological advances in systems biology and synthetic biology.
Spirulina's extracted blue color is used as a natural food coloring.
Researchers from several space agencies argue that cyanobacteria could be used for producing goods for human consumption in future crewed outposts on Mars, by transforming materials available on this planet. | 0 | Theoretical and Fundamental Chemistry |
Surface-enhanced laser desorption/ionization (SELDI) is a soft ionization method in mass spectrometry (MS) used for the analysis of protein mixtures. It is a variation of matrix-assisted laser desorption/ionization (MALDI). In MALDI, the sample is mixed with a matrix material and applied to a metal plate before irradiation by a laser, whereas in SELDI, proteins of interest in a sample become bound to a surface before MS analysis. The sample surface is a key component in the purification, desorption, and ionization of the sample. SELDI is typically used with time-of-flight (TOF) mass spectrometers and is used to detect proteins in tissue samples, blood, urine, or other clinical samples, however, SELDI technology can potentially be used in any application by simply modifying the sample surface. | 1 | Applied and Interdisciplinary Chemistry |
Marine macrophytes (i.e., macroalgae and seagrass) are highly productive and extend over large areas in coastal waters but their production of DOC has not received much attention. Macrophytes release DOC during growth with a conservative estimate (excluding release from decaying tissues) suggesting that macroalgae release between 1-39% of their gross primary production, while seagrasses release less than 5% as DOC of their gross primary production. The released DOC has been shown to be rich in carbohydrates, with rates depending on temperature and light availability. Globally the macrophyte communities have been suggested to produce ~160 Tg C yr of DOC, which is approximately half the annual global river DOC input (250 Tg C yr). | 1 | Applied and Interdisciplinary Chemistry |
In some cases, the stereochemistry of the starting material can prevent the formation of the Zaytsev product. For example, when menthyl chloride is treated with sodium ethoxide, the Hofmann product is formed exclusively, but in very low yield:
This result is due to the stereochemistry of the starting material. E2 eliminations require anti-periplanar geometry, in which the proton and leaving group lie on opposite sides of the C-C bond, but in the same plane. When menthyl chloride is drawn in the chair conformation, it is easy to explain the unusual product distribution.
Formation of the Zaytsev product requires elimination at the 2-position, but the isopropyl group – not the proton – is anti-periplanar to the chloride leaving group; this makes elimination at the 2-position impossible. In order for the Hofmann product to form, elimination must occur at the 6-position. Because the proton at this position has the correct orientation relative to the leaving group, elimination can and does occur. As a result, this particular reaction produces only the Hofmann product. | 0 | Theoretical and Fundamental Chemistry |
A dilute solution of a certain polymer has a unique feature: all polymers are considered independent from each other, so that interactions between polymers may be neglected. By illuminating such a solution with a ray of considerable width, a macroscopic number of chain conformations are being sampled simultaneously. In this situation the accessible observables are all ensemble averages, i.e. averages over all possible configurations and deformations of the polymer.
In such a solution, where the polymer density is low (dilute) enough, homogenous and isotropic (on average), intermolecular contributions to the structure factor are averaged out, and only the single-molecule/polymer structure factor is preserved:
with representing the ensemble average. This reduces to the following for an isotropic system (which is typically the case):
where two more definitions were made: and . | 0 | Theoretical and Fundamental Chemistry |
Inspired from the dirhodium tetraacetate bimetallic salt, synthetic chemists decided to explore the synthesis of paddlewheel mixed heteronuclear bismuth-rhodium salts. The synthesis involves treatment of the [Rh(OCR)] salt with the dibusmuth tetrafluoroacetate [Bi(OCCF)] equivalent. Depending on the nature and sterics of the R ligand, the resulting mixed salt has either two Bu R-substituents resulting in the cis mixed salt or a single Me R-substituent provenient from the dirhodium precursor (see scheme to the right). The mixed salts display increased air and moisture compared to the parental dimetallic salts and show Lewis acidity at the rhodium center. | 0 | Theoretical and Fundamental Chemistry |
Hydrometalation (hydrometallation) is a type of chemical reaction in organometallic chemistry in which a chemical compound with a hydrogen to metal bond (M-H, metal hydride) adds to compounds with an unsaturated bond like an alkene (RC=CR) forming a new compound with a carbon to metal bond (RHC-CRM). The metal is less electronegative than hydrogen, the reverse reaction is beta-hydride elimination. The reaction is structurally related to carbometalation. When the substrate is an alkyne the reaction product is a vinylorganometallic.
Examples are hydroboration, hydroalumination, hydrosilylation and hydrozirconation. | 0 | Theoretical and Fundamental Chemistry |
IRsweep is a Swiss company offering optical spectroscopy solutions and multipass absorption cells.
The spectroscopy is based on semiconductor quantum cascade laser frequency combs
in the mid-infrared wavelength range. The company is based in Zurich, Switzerland and was founded in 2014 and acquired by Sensirion Holding in May 2021.
The technology is used for high speed absorption measurements of different molecules and is robust against cross-sensitivities. Such sensor systems are in high demand for process analytics as well as research applications, as the mid-infrared range hosts the strongest absorption features of many molecules. | 0 | Theoretical and Fundamental Chemistry |
Acetone–butanol–ethanol (ABE) fermentation, also known as the Weizmann process, is a process that uses bacterial fermentation to produce acetone, n-butanol, and ethanol from carbohydrates such as starch and glucose. It was developed by chemist Chaim Weizmann and was the primary process used to produce acetone, which was needed to make cordite, a substance essential for the British war industry during World War I. | 1 | Applied and Interdisciplinary Chemistry |
A table with experimental single bonds for carbon to other elements is given below. Bond lengths are given in picometers. By approximation the bond distance between two different atoms is the sum of the individual covalent radii (these are given in the chemical element articles for each element). As a general trend, bond distances decrease across the row in the periodic table and increase down a group. This trend is identical to that of the atomic radius. | 0 | Theoretical and Fundamental Chemistry |
The pharynx is a part of the conducting zone of the respiratory system and also a part of the digestive system. It is the part of the throat immediately behind the nasal cavity at the back of the mouth and above the esophagus and larynx. The pharynx is made up of three parts. The lower two parts—the oropharynx and the laryngopharynx are involved in the digestive system. The laryngopharynx connects to the esophagus and it serves as a passageway for both air and food. Air enters the larynx anteriorly but anything swallowed has priority and the passage of air is temporarily blocked. The pharynx is innervated by the pharyngeal plexus of the vagus nerve. Muscles in the pharynx push the food into the esophagus. The pharynx joins the esophagus at the oesophageal inlet which is located behind the cricoid cartilage. | 1 | Applied and Interdisciplinary Chemistry |
Benefactor and corporate members can be companies, universities, national, regional or international organizations, laboratories, associations or any other structure active in or connected to the refrigeration industry or IIR activities. | 0 | Theoretical and Fundamental Chemistry |
This process consists of depositing a solid culture substrate, such as rice or wheat bran, on flatbeds after seeding it with microorganisms; the substrate is then left in a temperature-controlled room for several days.
Liquid state fermentation is performed in tanks, which can reach at an industrial scale. Liquid culture is ideal for the growing of unicellular organisms such as bacteria or yeasts.
To achieve liquid aerobic fermentation, it is necessary to constantly supply the microorganism with oxygen, which is generally done via stirring the fermentation media. Accurately managing the synthesis of the desired metabolites requires regulating temperature, soluble oxygen, ionic strength, pH and control nutrients.
Applying this growing technique to filamentous fungi leads to difficulties. The fungus develops in its vegetative form, generating hyphae or multicellular ramous filaments, while a septum separates the cells. As this mycelium develops in a liquid environment, it generates abundant viscosity in the growing medium, reducing oxygen solubility, while stirring disrupts the cell network increasing cell mortality.
In nature, filamentous fungi grow on the ground, decomposing vegetal compounds under naturally ventilated conditions. Therefore, solid state fermentation enables the optimal development of filamentous fungi, allowing the mycelium to spread on the surface of solid compounds among which air can flow.
Solid state fermentation uses culture substrates with low water levels (reduced water activity), which is particularly appropriate for mould. The methods used to grow filamentous fungi using solid state fermentation allow the best reproduction of their natural environment. The medium is saturated with water but little of it is free-flowing. The solid medium comprises both the substrate and the solid support on which the fermentation takes place. The substrate used is generally composed of vegetal byproducts such as beet pulp or wheat bran.
At the beginning of the growth process, the substrates and solid culture compounds are non-soluble compounds composed of very large, biochemically complex molecules that the fungus will cut off to get essential C and N nutrients. To develop its natural substrate, the fungal organism sets forth its entire genetic potential to produce the metabolites necessary for its growth. The composition of the growth medium guides the microorganism's metabolism towards the production of enzymes that release bio-available single molecules such as sugars or amino acids by carving out macromolecules. Therefore, when selecting the components of the growth medium it is possible to guide the cells towards the production of the desired metabolite(s), mainly enzymes that transform polymers (cellulose, hemicellulose, pectins, proteins) into single moieties in a very efficient and cost-effective manner.
Compared to submerged fermentation processes, solid state fermentation is more cost-effective: smaller vessels, lower water consumption, reduced wastewater treatment costs and lower energy consumption (no need to heat up water, poor mechanical energy input due to smooth stirring).
Cultivating on heterogeneous substrates requires expertise to maintain optimal growth conditions. Air flow monitoring is key because it impacts temperature, oxygen supply and moisture. In order to maintain sufficient moisture content for the growth of filamentous fungus, waterlogged air is used and may require further addition of water. In most cases, solid state fermentation does not require a completely sterile environment as the initial sterilization of the fermentation substrate associated with the rapid colonization of the substrate by the fungous microorganism limits the development of the autochthonous flora. | 1 | Applied and Interdisciplinary Chemistry |
The ideality factor (also called the emissivity factor) is a fitting parameter that describes how closely the diode's behavior matches that predicted by theory, which assumes the p-n junction of the diode is an infinite plane and no recombination occurs within the space-charge region. A perfect match to theory is indicated when . When recombination in the space-charge region dominate other recombination, however, . The effect of changing ideality factor independently of all other parameters is shown for a crystalline silicon solar cell in the I-V curves displayed in the figure to the right.
Most solar cells, which are quite large compared to conventional diodes, well approximate an infinite plane and will usually exhibit near-ideal behavior under standard test conditions (). Under certain operating conditions, however, device operation may be dominated by recombination in the space-charge region. This is characterized by a significant increase in I as well as an increase in ideality factor to . The latter tends to increase solar cell output voltage while the former acts to erode it. The net effect, therefore, is a combination of the increase in voltage shown for increasing n in the figure to the right and the decrease in voltage shown for increasing I in the figure above. Typically, I is the more significant factor and the result is a reduction in voltage.
Sometimes, the ideality factor is observed to be greater than 2, which is generally attributed to the presence of Schottky diode or heterojunction in the solar cell. The presence of a heterojunction offset reduces the collection efficiency of the solar cell and may contribute to low fill-factor. | 0 | Theoretical and Fundamental Chemistry |
Langgan () is the ancient Chinese name of a gemstone which remains an enigma in the history of mineralogy; it has been identified, variously, as blue-green malachite, blue coral, white coral, whitish chalcedony, red spinel, and red jade. It is also the name of a mythological langgan tree of immortality found in the western paradise of Kunlun Mountain, and the name of the classic waidan alchemical elixir of immortality langgan huadan 琅玕華丹 "Elixir Efflorescence of Langgan". | 1 | Applied and Interdisciplinary Chemistry |
In 2020 a spectroscopic analysis was reported to show signs of phosphine in the atmosphere of Venus in quantities that could not be explained by known abiotic processes. Later re-analysis of this work showed interpolation errors had been made, and re-analysis of data with the fixed algorithm do not result in the detection of phosphine. The authors of the original study then claimed to detect it with a much lower concentration of 1 ppb. | 0 | Theoretical and Fundamental Chemistry |
The apparent incorruptibility of an elixir-takers corpse is Needham and Lus second explanation for the persistent belief in immortality elixirs. They suggest that in some cases a body did not decompose because the deceased had died from mercury or arsenic poisoning, which is forensically known to often preserve a corpse from decay. For a believer in Daoist immortality drugs, even when an elixir-taker had unmistakably died, if the corpse was comparatively undecomposed, that could be interpreted as proof that the adept had become a xian immortal, as well as evidence for the alchemical elixir's efficacy.
Terminal incorruptibility was an ancient Chinese belief associated with jade, gold, and cinnabar. The Baopuzi says, "When gold and jade are inserted into the nine orifices, corpses do not decay. When salt and brine are absorbed into flesh and marrow, dried meats do not spoil. So when men ingest substances which are able to benefit their bodies and lengthen their days, why should it be strange that (some of these) should confer life perpetual?" The abolition of decay was believed to demonstrate the power of elixirs, "the corruptible had put on incorruptibility". Chinese jade burial suits are a better known example of using a mineral to preserve corpses.
There is a possibility that Sun Simiao (above) died from taking mercury elixirs. According to Suns hagiography in the 10th-century Xuxian zhuan' 續仙傳 (Further Biographies of the Immortals), after his death in 682 there was no visible sign of putrefaction, "After more than a month had passed there was no change in his appearance, and when the corpse was raised to be placed in the coffin it was as light as (a bundle of) empty clothes".
The incorruptibility stories about elixir users were not all myth, and recent archeological evidence showed that the ancient Chinese knew how "to achieve an almost perpetual conservation". The 1972 excavation of a tomb at Mawangdui discovered the extremely well-preserved body of Xin Zhui or Lady Dai, which resembled that of "a person who had died only a week or two before". A subsequent autopsy on her corpse found "abnormally high levels" of mercury and lead in her internal organs. | 1 | Applied and Interdisciplinary Chemistry |
Neptunes internal heat and convection drives cycles of methane, carbon, and a combination of other volatiles within Tritons lithosphere.
Models predicted the presence of seasonal nitrogen cycles on the moon Triton, however this has not been supported by observations to date. | 0 | Theoretical and Fundamental Chemistry |
Various governmental agencies involved with environmental protection and with occupational safety and health have promulgated regulations limiting the allowable concentrations of gaseous pollutants in the ambient air or in emissions to the ambient air. Such regulations involve a number of different expressions of concentration. Some express the concentrations as ppmv and some express the concentrations as mg/m, while others require adjusting or correcting the concentrations to reference conditions of moisture content, oxygen content or carbon dioxide content. This article presents a set of useful conversions and formulas for air dispersion modeling of atmospheric pollutants and for complying with the various regulations as to how to express the concentrations obtained by such modeling. | 1 | Applied and Interdisciplinary Chemistry |
Short-wave UV light is harmful to humans. In addition to causing sunburn and (over time) skin cancer, this light can produce extremely painful inflammation of the cornea of the eye, which may lead to temporary or permanent vision impairment. For this reason, the light produced by a germicidal lamp must be carefully shielded against direct viewing, with consideration of reflections and dispersed light. A February 2017 risk analysis of UVC lights concluded that ultraviolet light from these lamps can cause skin and eye problems. | 0 | Theoretical and Fundamental Chemistry |
The unambiguous mechanism of the antigen transfer is still unknown. However, there are three possible ways: I. acquisition of mTEC apoptotic bodies, which could possibly be related with low mTEC lifespan II. acquisition of exosomes and III. acquisition via trogocytosis, how antigen transfer can be mediated.
There is also an evidence, that antigen transfer and therefore indirect presentation by thymic DCs are regulated by PGE activator Aire. | 1 | Applied and Interdisciplinary Chemistry |
Diethyl azodicarboxylate, conventionally abbreviated as DEAD and sometimes as DEADCAT, is an organic compound with the structural formula . Its molecular structure consists of a central azo functional group, RN=NR, flanked by two ethyl ester groups. This orange-red liquid is a valuable reagent but also quite dangerous and explodes upon heating. Therefore, commercial shipment of pure diethyl azodicarboxylate is prohibited in the United States and is carried out either in solution or on polystyrene particles.
DEAD is an aza-dienophile and an efficient dehydrogenating agent, converting alcohols to aldehydes, thiols to disulfides and hydrazo groups to azo groups; it is also a good electron acceptor. While DEAD is used in numerous chemical reactions it is mostly known as a key component of the Mitsunobu reaction, a common strategy for the preparation of an amine, azide, ether, thioether, or ester from the corresponding alcohol. It is used in the synthesis of various natural products and pharmaceuticals such as zidovudine, an AIDS drug; FdUMP, a potent antitumor agent; and procarbazine, a chemotherapy drug. | 0 | Theoretical and Fundamental Chemistry |
Macroscopic optical elements and active optical components as well as large area hot mirrors, cold mirrors, lenses, and beam splitters can be made by the sol–gel route. In the processing of high performance ceramic nanomaterials with superior opto-mechanical properties under adverse conditions, the size of the crystalline grains is determined largely by the size of the crystalline particles present in the raw material during the synthesis or formation of the object. Thus a reduction of the original particle size well below the wavelength of visible light (~500 nm) eliminates much of the light scattering, resulting in a translucent or even transparent material.
Furthermore, microscopic pores in sintered ceramic nanomaterials, mainly trapped at the junctions of microcrystalline grains, cause light to scatter and prevented true transparency. The total volume fraction of these nanoscale pores (both intergranular and intragranular porosity) must be less than 1% for high-quality optical transmission, i.e. the density has to be 99.99% of the theoretical crystalline density. | 0 | Theoretical and Fundamental Chemistry |
The SUV has emerged as a clinically useful, albeit controversial, semi-quantitative tool in PET analysis. Standardizing imaging protocols and measuring the SUV at the same time post-injection of the radiotracer, is necessary to obtain a correct SUV because imaging before the uptake plateau introduces unpredictable errors of up to 50% with SUVs. Noise, image resolution, and reconstruction do affect the accuracy of SUVs, but correction with phantom can minimize these differences when comparing SUVs for multi-centre clinical trials. SUV may lack sensitivity in measuring response to treatment as it is a simple measure of tracer uptake in bone, which is affected by the tracer uptake in other competing tissues and organs in addition to the target ROI. | 1 | Applied and Interdisciplinary Chemistry |
Hexamethylenetetramine was discovered by Aleksandr Butlerov in 1859.
It is prepared industrially by combining formaldehyde and ammonia:
The reaction can be conducted in gas phase and in solution.
The molecule has a tetrahedral cage-like structure, similar to adamantane. Four vertices are occupied by nitrogen atoms, which are linked by methylene groups. Although the molecular shape defines a cage, no void space is available at the interior for binding other atoms or molecules, unlike crown ethers or larger cryptand structures.
The molecule behaves like an amine base, undergoing protonation and N-alkylation (). | 0 | Theoretical and Fundamental Chemistry |
The name Vaiśeṣika Sūtra (Sanskrit: वैशेषिक सूत्र) is derived from viśeṣa, विशेष, which means "particularity", that is to be contrasted from "universality". The classes particularity and universality belong to different categories of experience. | 1 | Applied and Interdisciplinary Chemistry |
The discovery that a hormone can influence phosphoinositide metabolism was made by Mabel R. Hokin (1924–2003) and her husband Lowell E. Hokin in 1953, when they discovered that radioactive P phosphate was incorporated into the phosphatidylinositol of pancreas slices when stimulated with acetylcholine. Up until then phospholipids were believed to be inert structures only used by cells as building blocks for construction of the plasma membrane.
Over the next 20 years, little was discovered about the importance of PIP metabolism in terms of cell signaling, until the mid-1970s when Robert H. Michell hypothesized a connection between the catabolism of PIP and increases in intracellular calcium (Ca) levels. He hypothesized that receptor-activated hydrolysis of PIP produced a molecule that caused increases in intracellular calcium mobilization. This idea was researched extensively by Michell and his colleagues, who in 1981 were able to show that PIP is hydrolyzed into DAG and IP by a then unknown phosphodiesterase. In 1984 it was discovered that IP acts as a secondary messenger that is capable of traveling through the cytoplasm to the endoplasmic reticulum (ER), where it stimulates the release of calcium into the cytoplasm.
Further research provided valuable information on the IP pathway, such as the discovery in 1986 that one of the many roles of the calcium released by IP is to work with DAG to activate protein kinase C (PKC). It was discovered in 1989 that phospholipase C (PLC) is the phosphodiesterase responsible for hydrolyzing PIP into DAG and IP. Today the IP signaling pathway is well mapped out, and is known to be important in regulating a variety of calcium-dependent cell signaling pathways. | 1 | Applied and Interdisciplinary Chemistry |
Starvation response in animals (including humans) is a set of adaptive biochemical and physiological changes, triggered by lack of food or extreme weight loss, in which the body seeks to conserve energy by reducing metabolic rate and/or non-resting energy expenditure to prolong survival and preserve body fat and lean mass.
Equivalent or closely related terms include famine response, starvation mode, famine mode, starvation resistance, starvation tolerance, adapted starvation, adaptive thermogenesis, fat adaptation, and metabolic adaptation. | 1 | Applied and Interdisciplinary Chemistry |
Unresolved complex mixture (UCM), or hump, is a feature frequently observed in gas chromatographic (GC) data of crude oils and extracts from organisms exposed to oil.
The reason for the UCM hump appearance is that GC cannot resolve and identify a significant part of the hydrocarbons in crude oils. The resolved components appear as peaks while the UCM appears as a large background/platform. In non-biodegraded oils the UCM may comprise less than 50% of the total area of the chromatogram, while in biodegraded oils this figure can rise to over 90%. UCMs are also observed in certain refined fractions such as lubricating oils and references therein.
One reason why it is important to study the nature of UCMs is that some have been shown to contain toxic components, but only a small range of known petrogenic toxicants, such as the USEPA list of 16 polycyclic aromatic hydrocarbons (PAHs), tend to be routinely monitored in the environment.
Analysis of the hydrocarbon fraction of crude oils by GC reveals a complex mixture containing many thousands of individual components. Components that are resolved by GC have been extensively studied e.g. However, despite the application of many analytical techniques the remaining components have, until very recently, proved difficult to separate due to the large numbers of co-eluting compounds. Gas chromatograms of mature oils have prominent n-alkane peaks which distract attention from the underlying unresolved complex mixture (UCM) of hydrocarbons often referred to as the ‘hump’. Processes such as weathering and biodegradation result in a relative enrichment of the UCM component by removal of resolved components and the creation of new compounds. It has been shown that both resolved and unresolved components of oils are subject to concurrent biodegradation, i.e. it is not a sequential process, but due to the recalcitrant nature of some components, the rates of biodegradation of individual compounds greatly varies. The UCM fraction often represents the major component of hydrocarbons within hydrocarbon-polluted sediments (see reference therein) and biota e.g. A number of studies has now demonstrated that aqueous exposure to components within the UCM can affect the health of marine organisms, including possible hormonal disruption, and high concentrations of environmental UCMs have been strongly implicated with impaired health in wild populations. | 0 | Theoretical and Fundamental Chemistry |
Homoenolates are a type of functional group that have been used in synthetic organic chemistry since the 1980s. They are related to enolates, but represent an umpolung of their reactivity. Homoenolates can be formed with a variety of different metal counterions, including lithium, iron, silver, lead, titanium, tin, tellurium, zirconium, niobium, mercury, zinc, antimony, bismuth, nickel, palladium, and copper. Homoenolates stability and reactivity varies by counterion identity and other nearby functional groups. Common pathways of decomposition include proto-demetalation and β-hydride elimination. Multiple reviews on the topic of homoenolates and their reactivity have been published. | 0 | Theoretical and Fundamental Chemistry |
In implementing the CWA, the U.S. Environmental Protection Agency (EPA) defined BMP in the federal wastewater permit regulations, initially to refer to auxiliary procedures for industrial wastewater controls.
:...schedules of activities, prohibitions of practices, maintenance procedures, and other management practices to prevent or reduce the pollution of waters of the United States, BMPs also include treatment requirements, operating procedures, and practices to control plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage.
Later the Agency added a reference to stormwater management BMPs.
:...each NPDES permit shall include conditions meeting the following requirements when applicable... (k) Best management practices (BMPs) to control or abate the discharge of pollutants when: ... (2) Authorized under section 402(p) of the CWA for the control of storm water discharges... | 1 | Applied and Interdisciplinary Chemistry |
Concerns regarding the persistence in the environment and toxicity to various flora and fauna of oil dispersants date back to their early use in the 1960s and 1970s. Both the degradation and the toxicity of dispersants depend on the chemicals chosen within the formulation. Compounds which interact too harshly with oil dispersants should be tested to ensure that they meet three criteria:
* They should be biodegradable.
* In the presence of oil, they must not be preferentially utilized as a carbon source.
* They must be nontoxic to indigenous bacteria. | 1 | Applied and Interdisciplinary Chemistry |
Solvent vapor annealing (SVA) is a widely used technique for controlling the morphology and ordering of block copolymer (BCP) films. By controlling the block ratio (f = N/N), spheres, cylinders, gyroids , and lamellae structures can be generated by forming a swollen and mobile layer of thin-film from added solvent vapor to facilitate the self-assembly of the polymer blocks. The process allows increased lateral ordering by several magnitudes to previous methods. It is a more mild alternative to thermal annealing.
Ideally, the chamber in which SVA takes place is a metal chamber that is inert to reaction with the given solvent, allowing for high precision in forming the desired nanostructures. Computers with designed program control of the valves for solvent addition and withdrawal are used to increase precision as well. This regulated inlet along with close monitoring of pressure gauges and thickness allows instant response and control while the annealing and evaporation phases precede. | 0 | Theoretical and Fundamental Chemistry |
Attenuation was first observed by Charles Yanofsky in the trp operon of E. coli. The first observation was linked to two separate scientific facts. Mutations which knocked out the trp R (repressor) gene still showed some regulation of the trp operon (these mutants were not fully induced/repressed by tryptophan). The total range of trp operon regulation is about 700 X (on/off). When the trp repressor was knocked out, one still got about 10 X regulation by the absence or presence of trp. When the sequence of the beginning of the trp operon was determined an unusual open reading frame (ORF) was seen immediately preceding the ORFs for the known structural genes for the tryptophan biosynthetic enzymes. The general structural information shown below was observed from the sequence of the trp operon.
First, Yanofsky observed that the ORF contained two tandem Trp codons and the protein had a Trp percent composition which was about 10X normal. Second, the mRNA in this region contained regions of dyad symmetry which would allow it to form two mutually exclusive secondary structures. One of the structures looked exactly like a rho-independent transcription termination signal. The other secondary structure, if formed, would prevent the formation of this secondary structure and thus the terminator. This other structure is called the "preemptor". | 1 | Applied and Interdisciplinary Chemistry |
Early developments in organometallic chemistry include Louis Claude Cadets synthesis of methyl arsenic compounds related to cacodyl, William Christopher Zeises platinum-ethylene complex, Edward Franklands discovery of diethyl- and dimethylzinc, Ludwig Monds discovery of Ni(CO), and Victor Grignard's organomagnesium compounds. (Although not always acknowledged as an organometallic compound, Prussian blue, a mixed-valence iron-cyanide complex, was first prepared in 1706 by paint maker Johann Jacob Diesbach as the first coordination polymer and synthetic material containing a metal-carbon bond.) The abundant and diverse products from coal and petroleum led to Ziegler–Natta, Fischer–Tropsch, hydroformylation catalysis which employ CO, H, and alkenes as feedstocks and ligands.
Recognition of organometallic chemistry as a distinct subfield culminated in the Nobel Prizes to Ernst Fischer and Geoffrey Wilkinson for work on metallocenes. In 2005, Yves Chauvin, Robert H. Grubbs and Richard R. Schrock shared the Nobel Prize for metal-catalyzed olefin metathesis. | 0 | Theoretical and Fundamental Chemistry |
Amorphous solids typically exhibit higher localization of heat carriers compared to crystalline, giving rise to low thermal conductivity. Products for thermal protection, such as thermal barrier coatings and insulation, rely on materials with ultralow thermal conductivity. | 0 | Theoretical and Fundamental Chemistry |
The history of penicillin follows observations and discoveries of evidence of antibiotic activity of the mould Penicillium that led to the development of penicillins that became the first widely used antibiotics. Following the production of a relatively pure compound in 1942, penicillin was the first naturally-derived antibiotic.
Ancient societies used moulds to treat infections, and in the following centuries many people observed the inhibition of bacterial growth by moulds. While working at St Marys Hospital in London in 1928, Scottish physician Alexander Fleming was the first to experimentally determine that a Penicillium mould secretes an antibacterial substance, which he named "penicillin". The mould was found to be a variant of Penicillium notatum (now called Penicillium rubens), a contaminant of a bacterial culture in his laboratory. The work on penicillin at St Marys ended in 1929.
In 1939, a team of scientists at the Sir William Dunn School of Pathology at the University of Oxford, led by Howard Florey that included Edward Abraham, Ernst Chain, Mary Ethel Florey, Norman Heatley and Margaret Jennings, began researching penicillin. They developed a method for cultivating the mould and extracting, purifying and storing penicillin from it, together with an assay for measuring its purity. They carried out experiments with animals to determine penicillin's safety and effectiveness before conducting clinical trials and field tests. They derived its chemical structure and determined how it works. The private sector and the United States Department of Agriculture located and produced new strains and developed mass production techniques. During the Second World War penicillin became an important part of the Allied war effort, saving thousands of lives. Alexander Fleming, Howard Florey and Ernst Chain shared the 1945 Nobel Prize in Physiology or Medicine for the discovery and development of penicillin.
After the end of the war in 1945, penicillin became widely available. Dorothy Hodgkin determined its chemical structure, for which she received the Nobel Prize in Chemistry in 1964. This led to the development of semisynthetic penicillins that were more potent and effective against a wider range of bacteria. The drug was synthesised in 1957, but cultivation of mould remains the primary means of production. It was discovered that adding penicillin to animal feed increased weight gain, improved feed-conversion efficiency, promoted more uniform growth and facilitated disease control. Agriculture became a major user of penicillin. Shortly after their discovery of penicillin, the Oxford team reported penicillin resistance in many bacteria. Research that aims to circumvent and understand the mechanisms of antibiotic resistance continues today. | 1 | Applied and Interdisciplinary Chemistry |
Dexchlorpheniramine is an antihistamine, or an antagonist of the histamine H receptor. A study found that dexchlorpheniramine had a K value of 20 to 30 μM for the muscarinic acetylcholine receptors using rat brain tissue. | 0 | Theoretical and Fundamental Chemistry |
The mechanism behind episomal retention in the case of S/MAR episomes is generally still uncertain.
As of 1985, in the case of latent Epstein-Barr virus infection, episomes seemed to be associated with nuclear proteins of the host cell through a set of viral proteins. | 1 | Applied and Interdisciplinary Chemistry |
From 1997, Waters was an honorary senior research fellow at Massey University's Albany campus, where his wife Joyce was a professor of chemistry.
In 2002, Massey Universitys governing council considered restoring Waters to the vice-chancellorship as an interim replacement following the retirement of his successor, James McWha; however, the board was prevented from doing so by the State Sector Act 1988, which barred the appointment of someone not already on the universitys payroll; Waters had since moved to Auckland and no longer worked in the university sector.
Waters died in Auckland on 7 June 2018, aged 87. | 0 | Theoretical and Fundamental Chemistry |
In 1985, Donna Strickland and Gérard Mourou invented a method to amplify laser pulses by "chirping". This changed a single wavelength into a full spectrum. The system amplified the beam at each wavelength and then reversed the beam into one color. Chirp pulsed amplification became instrumental for NIF and the Omega EP system.
LANL constructed a series of laser facilities. They included Gemini (a two beam system), Helios (eight beams), Antares (24 beams) and Aurora (96 beams). The program ended in the early nineties with a cost on the order of one billion dollars.
In 1987, Akira Hasegawa noticed that in a dipolar magnetic field, fluctuations tended to compress the plasma without energy loss. This effect was noticed in data taken by Voyager 2, when it encountered Uranus. This observation became the basis for a fusion approach known as the levitated dipole.
In tokamaks, the Tore Supra was under construction from 1983 to 1988 in Cadarache, France. Its superconducting magnets permitted it to generate a strong permanent toroidal magnetic field. First plasma came in 1988.
In 1983, JET achieved first plasma. In 1985, the Japanese tokamak, JT-60 produced its first plasmas. In 1988, the T-15 a Soviet tokamak was completed, the first to use (helium-cooled) superconducting magnets.
In 1998, the T-15 Soviet tokamak with superconducting helium-cooled coils was completed. | 0 | Theoretical and Fundamental Chemistry |
The Ferrier Research Institute at Victoria University of Wellington was named for Ferrier. It was created on 6 January 2014 to accommodate the group of carbohydrate chemists who left Callaghan Innovation on that date. (Callaghan Innovation was previously Industrial Research Ltd.) | 0 | Theoretical and Fundamental Chemistry |
Neptunium diarsenide is a binary inorganic compound of neptunium and arsenic with the chemical formula . The compound forms crystals. | 0 | Theoretical and Fundamental Chemistry |
There are numerous methods that have been designed to accurately measure coupling constant between nuclei. They have been classified into two groups: frequency based methods where separation of peaks centers (splitting) is measured in a frequency domain, and intensity based methods where the coupling is extracted from the resonance intensity instead of splitting. The two methods complement each other as each of them is subject to a different kind of systematic errors. Here are the prototypical examples of NMR experiments belonging to each of the two groups:
* Intensity methods: quantitative J-modulation experiment and phase modulated methods
* frequency resolved methods: SCE-HSQC, E. COSY and spin state selective experiments | 0 | Theoretical and Fundamental Chemistry |
Tetsuo Nozoe (野副 鉄男, 16 May 1902 – 4 April 1996) was a Japanese organic chemist. He is known for the discovery of hinokitiol, a seven-membered aromatic compound, and studying non-benzenoid aromatic compounds. | 0 | Theoretical and Fundamental Chemistry |
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