text stringlengths 105 4.57k | label int64 0 1 | label_text stringclasses 2 values |
|---|---|---|
Stable cell-cell interactions are required for cell adhesion within a tissue and controlling the shape and function of cells. These stable interactions involve cell junctions which are multiprotein complexes that provide contact between neighboring cells. Cell junctions allow for the preservation and proper functioning of epithelial cell sheets. These junctions are also important in the organization of tissues where cells of one type can only adhere to cells of the same tissue rather than to a different tissue. | 1 | Applied and Interdisciplinary Chemistry |
In an HCP crystal such as graphite, the two coordinates include the origin and the next plane up the c axis located at c/2, and hence , which gives us
From this it is convenient to define dummy variable , and from there consider the modulus squared so hence
This leads us to the following conditions for the structure factor: | 0 | Theoretical and Fundamental Chemistry |
The Magnus effect is named after Gustav Magnus, the German physicist who investigated it. It describes the force generated by fluid flow over a rotating body, at right angles to both the direction of flow and the axis of rotation. This force on a rotating cylinder is known as Kutta–Joukowski lift, after Martin Kutta and Nikolai Zhukovsky (or Joukowski), who first analyzed the effect.
The Flettner rotor is just one form of the Magnus rotor, which in general need not be cylindrical. | 1 | Applied and Interdisciplinary Chemistry |
Qin Shi Huang, the founder of the Qin dynasty (221–206 BCE), feared death and spent the last part of his life seeking the elixir of life. This led to later allegations that he died from elixir poisoning. The first emperor also sent Xu Fu to sail an expeditionary fleet into the Pacific seeking the legendary Mount Penglai where the busi zhi shu 不死之樹 "tree of deathlessness" grew, but they never returned. | 1 | Applied and Interdisciplinary Chemistry |
Defensive structures and chemicals are costly as they require resources that could otherwise be used by plants to maximize growth and reproduction. In some situations, plant growth slows down when most of the nutrients are being used for the generation of toxins or regeneration of plant parts. Many models have been proposed to explore how and why some plants make this investment in defenses against herbivores. | 1 | Applied and Interdisciplinary Chemistry |
In reproducing, most plants inherit their plastids from only one parent. In general, angiosperms inherit plastids from the female gamete, where many gymnosperms inherit plastids from the male pollen. Algae also inherit plastids from just one parent. Thus the plastid DNA of the other parent is completely lost.
In normal intraspecific crossingsresulting in normal hybrids of one speciesthe inheriting of plastid DNA appears to be strictly uniparental; i.e., from the female. In interspecific hybridisations, however, the inheriting is apparently more erratic. Although plastids are inherited mainly from the female in interspecific hybridisations, there are many reports of hybrids of flowering plants producing plastids from the male.
Approximately 20% of angiosperms, including alfalfa (Medicago sativa), normally show biparental inheriting of plastids. | 0 | Theoretical and Fundamental Chemistry |
In 1878 Josiah Willard Gibbs proposed that a droplet or crystal will arrange itself such that its surface Gibbs free energy is minimized by assuming a shape of low surface energy. He defined the quantity
Here represents the surface (Gibbs free) energy per unit area of the th crystal face and is the area of said face. represents the difference in energy between a real crystal composed of molecules with a surface and a similar configuration of molecules located inside an infinitely large crystal. This quantity is therefore the energy associated with the surface. The equilibrium shape of the crystal will then be that which minimizes the value of .
In 1901 Russian scientist George Wulff stated (without proof) that the length of a vector drawn normal to a crystal face will be proportional to its surface energy : . The vector is the "height" of the th face, drawn from the center of the crystal to the face; for a spherical crystal this is simply the radius. This is known as the Gibbs-Wulff theorem.
In 1943 Laue gave a simple proof, which was extended in 1953 by Herring with a proof of the theorem and a method for determining the equilibrium shape of a crystal, consisting of two main exercises. To begin, a polar plot of surface energy as a function of orientation is made. This is known as the gamma plot and is usually denoted as , where denotes the surface normal, e.g., a particular crystal face. The second part is the Wulff construction itself in which the gamma plot is used to determine graphically which crystal faces will be present. It can be determined graphically by drawing lines from the origin to every point on the gamma plot. A plane perpendicular to the normal is drawn at each point where it intersects the gamma plot. The inner envelope of these planes forms the equilibrium shape of the crystal.
The Wulff construction is for the equilibrium shape, but there is a corresponding form called the "kinetic Wulff construction" where the surface energy is replaced by a growth velocity. There are also variants that can be used for particles on surfaces and with twin boundaries. | 0 | Theoretical and Fundamental Chemistry |
The French group for the study of polymers and their application, also called more simply French polymer group (GFP) is a French nonprofit organization and learned society, which aims to promote polymer chemistry, physics, and material science in French industry and institutes of higher learning. | 1 | Applied and Interdisciplinary Chemistry |
The waste discharge can be used as land stabilizer as dry bio-solids that can be distributed to the market. The land stabilizer is used in reclaiming marginal land such as mining waste land. This process will help to restore the land to its initial appearance. | 0 | Theoretical and Fundamental Chemistry |
Esketamine is used for similar indications as ketamine. Such uses include induction of anesthesia in high-risk patients such as those with circulatory shock, severe bronchospasm, or as a supplement to regional anesthesia with incomplete nerve blocks. | 0 | Theoretical and Fundamental Chemistry |
In biochemistry, an Eadie–Hofstee plot (or Eadie–Hofstee diagram) is a graphical representation of the Michaelis–Menten equation in enzyme kinetics. It has been known by various different names, including Eadie plot, Hofstee plot and Augustinsson plot. Attribution to Woolf is often omitted, because although Haldane and Stern credited Woolf with the underlying equation, it was just one of the three linear transformations of the Michaelis–Menten equation that they initially introduced. However, Haldane indicated latter that Woolf had indeed found the three linear forms: is plotted against , against , or against , the first plot being most convenient unless inhibition is being studied.</blockquote> | 1 | Applied and Interdisciplinary Chemistry |
The classification of AFPs became more complicated when antifreeze proteins from plants were discovered. Plant AFPs are rather different from the other AFPs in the following aspects:
#They have much weaker thermal hysteresis activity when compared to other AFPs.
#Their physiological function is likely in inhibiting the recrystallization of ice rather than in preventing ice formation.
#Most of them are evolved pathogenesis-related proteins, sometimes retaining antifungal properties. | 1 | Applied and Interdisciplinary Chemistry |
The name Akkermansia (Ak.ker.mansi.a.) derives from: Neo-Latin feminine gender noun Akkermansia, named after Anton Dirk Louis Akkermans (28 October 1940 – 21 August 2006), a Dutch microbiologist recognized for his contribution to microbial ecology. Neo-Latin neuter gender noun mucinum, mucin; Neo-Latin adjective philus from Greek adjective philos (φίλος) meaning friend, loving; Neo-Latin feminine gender adjective muciniphila', mucin-loving). | 1 | Applied and Interdisciplinary Chemistry |
ortho-Carborane is the organoboron compound with the formula CBH. The prefix ortho is derived from ortho. It is the most prominent carborane. This derivative has been considered for a wide range of applications from heat-resistant polymers to medical applications. It is a colorless solid that melts, without decomposition, at 320 °C | 0 | Theoretical and Fundamental Chemistry |
During the thirteenth century, Mosul, Iraq became home to a school of luxury metalwork which rose to international renown. Artifacts classified as Mosul are some of the most intricately designed and revered pieces of the Middle Ages. | 1 | Applied and Interdisciplinary Chemistry |
There are several challenges associated with gene silencing therapies, including delivery and specificity for targeted cells. For instance, for treatment of neurodegenerative disorders, molecules for a prospective gene silencing therapy must be delivered to the brain. The blood–brain barrier makes it difficult to deliver molecules into the brain through the bloodstream by preventing the passage of the majority of molecules that are injected or absorbed into the blood. Thus, researchers have found that they must directly inject the molecules or implant pumps that push them into the brain.
Once inside the brain, however, the molecules must move inside of the targeted cells. In order to efficiently deliver siRNA molecules into the cells, viral vectors can be used. Nevertheless, this method of delivery can also be problematic as it can elicit an immune response against the molecules. In addition to delivery, specificity has also been found to be an issue in gene silencing. Both antisense oligonucleotides and siRNA molecules can potentially bind to the wrong mRNA molecule. Thus, researchers are searching for more efficient methods to deliver and develop specific gene silencing therapeutics that are still safe and effective. | 1 | Applied and Interdisciplinary Chemistry |
Nested polymerase chain reaction (nested PCR) is a modification of polymerase chain reaction intended to reduce non-specific binding in products due to the amplification of unexpected primer binding sites. | 1 | Applied and Interdisciplinary Chemistry |
In the case of multiple charged projectile ions a particular form of electronic sputtering can take place that has been termed potential sputtering. In these cases the potential energy stored in multiply charged ions (i.e., the energy necessary to produce an ion of this charge state from its neutral atom) is liberated when the ions recombine during impact on a solid surface (formation of hollow atoms). This sputtering process is characterized by a strong dependence of the observed sputtering yields on the charge state of the impinging ion and can already take place at ion impact energies well below the physical sputtering threshold. Potential sputtering has only been observed for certain target species and requires a minimum potential energy. | 0 | Theoretical and Fundamental Chemistry |
Following Max Planck (1914), a radiative field is often described in terms of specific radiative intensity, which is a function of each geometrical point in a space region, at an instant of time. This is slightly different from Prevosts mode of definition, which was for regions of space. It is also slightly conceptually different from Prevosts definition: Prevost thought in terms of bound and free heat while today we think in terms of heat in kinetic and other dynamic energy of molecules, that is to say heat in matter, and the thermal photon gas. A detailed definition is given by R. M. Goody and Y. L. Yung (1989). They think of the interconversion between thermal radiation and heat in matter. From the specific radiative intensity they derive , the monochromatic vector flux density of radiation at each point in a region of space, which is equal to the time averaged monochromatic Poynting vector at that point (D. Mihalas 1978 on pages 9–11). They define the monochromatic volume-specific rate of gain of heat by matter from radiation as the negative of the divergence of the monochromatic flux density vector; it is a scalar function of the position of the point:
They define (pointwise) monochromatic radiative equilibrium by
: at every point of the region that is in radiative equilibrium.
They define (pointwise) radiative equilibrium by
: at every point of the region that is in radiative equilibrium.
This means that, at every point of the region of space that is in (pointwise) radiative equilibrium, the total, for all frequencies of radiation, interconversion of energy between thermal radiation and energy content in matter is nil(zero). Pointwise radiative equilibrium is closely related to Prevost's absolute radiative equilibrium.
D. Mihalas and B. Weibel-Mihalas (1984) emphasise that this definition applies to a static medium, in which the matter is not moving. They also consider moving media. | 0 | Theoretical and Fundamental Chemistry |
In the future alternative marker technologies will need to be used more often to, at the least, assuage concerns about their persistence into the final product. It is also possible that markers will be replaced entirely by future techniques which use removable markers, and others which do not use markers at all, instead relying on co-transformation, homologous recombination, and recombinase-mediated excision. | 1 | Applied and Interdisciplinary Chemistry |
This case was appealed to the Supreme Court as Addyston Pipe and Steel Company v. United States, 175 U.S. 211 (1899). However, on appeal, the defendants did not attack the reasoning of the Sixth Circuit. Instead, they argued that the Commerce Clause of the Constitution did not empower Congress to regulate purely private agreements but instead authorized Congress only to remove barriers to interstate commerce erected by individual states. They argued that even if Congress possessed the authority to regulate purely private agreements, banning defendants cartel would infringe liberty of contract because the defendants cartel purportedly set reasonable prices. The defendants' last argument was that their cartel did not directly restrain trade but was simply a partial restraint, which ensured the defendants merely a reasonable rate of return and thus would have been enforceable at common law.
The Court, in an opinion by Justice Peckham, rejected all three arguments and affirmed the decision of the Court of Appeals. Peckham conceded that the framers and ratifiers of the Constitution likely anticipated that the Commerce Clause would authorize mainly Congressional interdiction of state-created barriers to interstate commerce. At the same time, Peckham observed that in some cases, purely private agreements can have the same economic impact and directly restrain commerce among the several states. Moreover, Peckham also held that contracts that directly restrain trade are not the sort of ordinary contracts and combinations that find shelter in liberty of contract. Finally, Peckham held that the defendants cartel directly restrained trade. Peckham quoted extensively from Judge Tafts opinion below, which found, as a matter of fact, that the defendants cartel set unreasonable prices. See 85 F. 291–93. In particular, Peckham quoted Tafts finding that pipe produced by the cartel could have been produced and delivered to Atlanta for a cost, including a reasonable profit and the cost of transportation, or $17 or $18 per ton, but the cartel charged instead $24.25 per ton. | 1 | Applied and Interdisciplinary Chemistry |
The optical microscope, scanning electron microscope, X-ray diffraction and petrographic analysis can be used to determine the types and distribution of minerals in slag. The minerals present in the slag are good indicators of the gas atmosphere in the furnace, the cooling rate of the slag and the homogeneity of the slag. The type of ore and flux used in the smelting process can be determined if there are elements of un-decomposed charge or even metal pills trapped in the slag.
Slag minerals are classified as silicates, oxides and sulfides. Bachmann classified the main silicates in slag according to the ratio between metal oxides and silica.
:::::Ratio MeO : SiO silicate examples
:::::::2 : 1 fayalite
:::::::2 : 1 monticellite
:::::::1.5 : 1 melilite
:::::::1 : 1 pyroxene
Fayalite (FeSiO) is the most common mineral found in ancient slag. By studying the shape of the fayalite, the cooling rates of the slag can be roughly estimated.
Fayalite reacts with oxygen to form magnetite:
:3FeSiO + O= 2FeO·FeO + 3SiO
Therefore, the gas atmosphere in the furnace can be calculated from the ratio of magnetite to fayalite in the slag.
The presence of metal sulfides suggests that a sulfidic ore has been used. Metal sulfides survive the oxidizing stage before smelting and therefore may also indicate a multi-stage smelting process.
When fayalite is replete with CaO, monticellite and pyroxene form. They are an indicator of a high calcium content in the ore. | 1 | Applied and Interdisciplinary Chemistry |
The AnMBR technology goes through two stages to ensure maximum solid-liquid separation, adhering to increasing standards for effluent. First, the wastewater enters the anaerobic bioreactor unit, where the organic load goes through the anaerobic process to be transformed into biogas. Subsequently, the remaining liquid, which still has small amounts of solids, goes into the membrane unit, to separate the remaining, smaller solid particles from the anaerobically treated wastewater. This wastewater, otherwise known as effluent, can now either directly be recycled, or can further be treated by Reverse osmosis. The remaining solid particles are then cycled back to the anaerobic bioreactor unit where they can go through the biogas production process. Overall, this process removes 99% of the organic load contained within wastewater, and also produces biogas with a 70% purity. | 1 | Applied and Interdisciplinary Chemistry |
The ICRP states; "Collective effective dose is an instrument for optimisation, for comparing radiological technologies and protection procedures. Collective effective dose is not intended as a tool for epidemiological studies, and it is inappropriate to use it in risk projections. This is because the assumptions implicit in the calculation of collective effective dose (e.g., when applying the LNT model) conceal large biological and statistical uncertainties. Specifically, the computation of cancer deaths based on collective effective doses involving trivial exposures to large populations is not reasonable and should be avoided.
All calculations that involve adding doses assume the Linear no-threshold model (LNT) for health effects. Particularly the collective dose will not give a good indication of health consequences where the doses to some individuals are large enough to cause to deterministic effects.
The cancer risk due to a unit dose of radiation depends on the age and other characteristics of the population. Small local populations, for example radiation workers, may not have a typical population profile.
Both LNT and the concept of "collective dose" are criticized as speculative, lacking empirical evidence and based on unproved assumption that radiation "effect is cumulative over one’s lifetime, regardless of how low the rate of delivery of that dose (dose rate)".
Releases of radioisotopes can expose future generations to ionizing radiation and the calculation of the collective dose from such releases will contain uncertainties. For example, it is impossible to be sure of future population sizes and habits (e.g. diet and agricultural practices). Also the effects of a given radiation dose in the future may be greater (longer life expectancies) or less (improvements in cancer treatment) than for current exposures.
When calculating the total collective dose due to a release of long-lived radionuclides (e.g. Carbon-14) it is necessary to make assumptions about the habits and population sizes of future generations, and sometimes it is assumed that population sizes and behaviour remain the same for all time. | 0 | Theoretical and Fundamental Chemistry |
In outer-sphere ET reactions, the participating redox centers are not linked via any bridge during the ET event. Instead, the electron "hops" through space from the reducing center to the acceptor. Outer sphere electron transfer can occur between different chemical species or between identical chemical species that differ only in their oxidation state. The latter process is termed self-exchange. As an example, self-exchange describes the degenerate reaction between permanganate and its one-electron reduced relative manganate:
:[MnO] + [Mn*O] → [MnO] + [Mn*O]
In general, if electron transfer is faster than ligand substitution, the reaction will follow the outer-sphere electron transfer.
Often occurs when one/both reactants are inert or if there is no suitable bridging ligand.
A key concept of Marcus theory is that the rates of such self-exchange reactions are mathematically related to the rates of "cross reactions". Cross reactions entail partners that differ by more than their oxidation states. One example (of many thousands) is the reduction of permanganate by iodide to form iodine and, again, manganate. | 0 | Theoretical and Fundamental Chemistry |
Von Kármán swirling flow finds its applications in wide range of fields, which includes rotating machines, filtering systems, computer storage devices, heat transfer and mass transfer applications, combustion-related problems, planetary formations, geophysical applications etc. | 1 | Applied and Interdisciplinary Chemistry |
A restriction fragment is a DNA fragment resulting from the cutting of a DNA strand by a restriction enzyme (restriction endonucleases), a process called restriction. Each restriction enzyme is highly specific, recognising a particular short DNA sequence, or restriction site, and cutting both DNA strands at specific points within this site. Most restriction sites are palindromic, (the sequence of nucleotides is the same on both strands when read in the 5 to 3 direction of each strand), and are four to eight nucleotides long. Many cuts are made by one restriction enzyme because of the chance repetition of these sequences in a long DNA molecule, yielding a set of restriction fragments. A particular DNA molecule will always yield the same set of restriction fragments when exposed to the same restriction enzyme. Restriction fragments can be analyzed using techniques such as gel electrophoresis or used in recombinant DNA technology. | 1 | Applied and Interdisciplinary Chemistry |
Butyric acid is used in the preparation of various butyrate esters. It is used to produce cellulose acetate butyrate (CAB), which is used in a wide variety of tools, paints, and coatings, and is more resistant to degradation than cellulose acetate. CAB can degrade with exposure to heat and moisture, releasing butyric acid.
Low-molecular-weight esters of butyric acid, such as methyl butyrate, have mostly pleasant aromas or tastes. As a consequence, they are used as food and perfume additives. It is an approved food flavoring in the EU FLAVIS database (number 08.005).
Due to its powerful odor, it has also been used as a fishing bait additive. Many of the commercially available flavors used in carp (Cyprinus carpio) baits use butyric acid as their ester base. It is not clear whether fish are attracted by the butyric acid itself or the substances added to it. Butyric acid was one of the few organic acids shown to be palatable for both tench and bitterling. The substance has been used as a stink bomb by the Sea Shepherd Conservation Society to disrupt Japanese whaling crews. | 1 | Applied and Interdisciplinary Chemistry |
This bacterium was previously considered a fish pathogen, but it has recently emerged as a human pathogen. Aeromonas sp. have been isolated from various infected sites from patients (bile, blood, peritoneal fluid, pus, stool and urine). All isolates produced the two principal AHLs, N-butanoylhomoserine lactone (C4-HSL) and N-hexanoyl homoserine lactone (C6-HSL). It has been documented that Aeromonas sobria has produced C6-HSL and two additional AHLs with N-acyl side chain longer than C6. | 1 | Applied and Interdisciplinary Chemistry |
A [2+2]-cycloaddition is a 4 electron process that brings together two components. Thus, by the above general WH rules, it is only allowed if the reaction is antarafacial with respect to exactly one component. This is the same conclusion reached with correlation diagrams in the section above.
A rare but stereochemically unambiguous example of a [2 + 2]-cycloaddition is shown on the right. The strain and steric properties of the trans double bond enables this generally kinetically unfavorable process. cis, trans-1,5-Cyclooctadiene is also believed to undergo dimerization via this mode. Ketenes are a large class of reactants favoring [2 + 2] cycloaddition with olefins. The MO analysis of ketene cycloaddition is rendered complicated and ambiguous by the simultaneous but independent interaction of the orthogonal orbitals of the ketene but may involve a [2 + 2] interaction as well. | 0 | Theoretical and Fundamental Chemistry |
The scholarship surrounding Mosul Metalwork has been ongoing for a very long time, since it became the first Islamic objects dart studied in Europe, due to its early arrival on the continent. The diverse opinions on what constitutes as Mosul Metalwork arise due to the styles dispersion across lands and through the component of signatures which identify creators as "al Mawsili", meaning "of Mosul". Within the section of metalwork with signatures, twenty-seven out of the thirty-five state themselves as "al- Mawsili". Out of those, eight state their provenance through the name of the people for which they were created along with statements declaring their engendering within Mosul. Some notable scholars that have helped shape the basis of this study include: Joseph Toussaint Reinaud, Henri Lavoix, Gaston Migeon, Max Van Berchem, Mehmed Aga-Oglu, David Storm Rice.
In the early years of Mosul Metalwork, around 1828, Joseph Toussaint Reinaud, published a collection that included the first item to clearly state its creation in Mosul, the Blacas ewer, an artifact consistently scrutinized by scholars when exploring Mosul style. Then in the 1860s the credibility of Mosul was being questioned by scholars, it was during that century that Henry Lavoix declared that Damascus, Aleppo, Mosul, and Egypt all created inlaid metalwork, but specifically singled out Mosul as a source for a unique style unseen throughout the medium.
A critical point in the scholarship came in the beginning of the 20th, through Gaston Migeon, whose claims over the precedency of Mosul caused objection and an urgency for reliability. Migeon also wrote the first comprehensive article introducing the inlaid Islamic metalwork. In the following years, the fluctuation of precedence of Mosul and the lack of it continued, leading up to David Storm Rice, who released the first series of articles exploring the complexities of multiple objects, a process similar to that of Max Van Brehmen and Mehmed Aga-Oglu, two scholars that impacted the relevance and viability of Mosul Metalwork, some of which included the Blacas Ewer, Louvre basin and the Munich Tray.
Present day, Mosul Metalwork is still elusive, and lacks a sustaining amount of scholarship, but scholars continue to construct a field that utilizes substantiated evidence through designs, inscription, and other items engendered specifically in Mosul around the 13th century. An example of this is represented in an article written by Ruba Kana' An who utilizes its iconography and description to construct the argument stating the Freer Ewer as one of many metalworks constructed in Mosul. | 1 | Applied and Interdisciplinary Chemistry |
Light from the Sun hitting lunar dust causes it to become positively charged from the photoelectric effect. The charged dust then repels itself and lifts off the surface of the Moon by electrostatic levitation. This manifests itself almost like an "atmosphere of dust", visible as a thin haze and blurring of distant features, and visible as a dim glow after the sun has set. This was first photographed by the Surveyor program probes in the 1960s, and most recently the Chang'e 3 rover observed dust deposition on lunar rocks as high as about 28 cm. It is thought that the smallest particles are repelled kilometers from the surface and that the particles move in "fountains" as they charge and discharge. | 0 | Theoretical and Fundamental Chemistry |
Anaerobic oxidation of iron and steel commonly finds place in oxygen-depleted environments, such as in permanently water-saturated soils, peat bogs or wetlands in which archaeological iron artefacts are often found.
Anaerobic oxidation of carbon steel of canisters and overpacks is also expected to occur in deep geological formations in which high-level radioactive waste and spent fuels should be ultimately disposed. Nowadays, in the frame of the corrosion studies related to HLW disposal, anaerobic corrosion of steel is receiving a renewed and continued attention. Indeed, it is essential to understand this process to guarantee the total containment of HLW waste in an engineered barrier during the first centuries or millennia when the radiotoxicity of the waste is high and when it emits a significant quantity of heat.
The question is also relevant for the corrosion of the reinforcement bars (rebars) in concrete (Aligizaki et al., 2000). This deals then with the service life of concrete structures, amongst others the near-surface vaults intended for hosting low-level radioactive waste. | 1 | Applied and Interdisciplinary Chemistry |
Bioluminescent bacteria are most abundant in marine environments during spring blooms when there are high nutrient concentrations. These light-emitting organisms are found mainly in coastal waters near the outflow of rivers, such as the northern Adriatic Sea, Gulf of Trieste, northwestern part of the Caspian Sea, coast of Africa and many more. These are known as milky seas. Bioluminescent bacteria are also found in freshwater and terrestrial environments but are less wide spread than in seawater environments. They are found globally, as free-living, symbiotic or parasitic forms and possibly as opportunistic pathogens. Factors that affect the distribution of bioluminescent bacteria include temperature, salinity, nutrient concentration, pH level and solar radiation. For example, Aliivibrio fischeri grows favourably in environments that have temperatures between 5 and 30 °C and a pH that is less than 6.8; whereas, Photobacterium phosphoreum thrives in conditions that have temperatures between 5 and 25 °C and a pH that is less than 7.0. | 1 | Applied and Interdisciplinary Chemistry |
The first true chromatography is usually attributed to the Russian-Italian botanist Mikhail Tsvet. Tsvet applied his observations with filter paper extraction to the new methods of column fractionation that had been developed in the 1890s for separating the components of petroleum. He used a liquid-adsorption column containing calcium carbonate to separate yellow, orange, and green plant pigments (what are known today as xanthophylls, carotenes, and chlorophylls, respectively). The method was described on December 30, 1901, at the 11th Congress of Naturalists and Doctors (XI съезд естествоиспытателей и врачей) in Saint Petersburg. The first printed description was in 1903, in the Proceedings of the Warsaw Society of Naturalists, section of biology. He first used the term chromatography in print in 1906 in his two papers about chlorophyll in the German botanical journal, Berichte der Deutschen Botanischen Gesellschaft. In 1907 he demonstrated his chromatograph for the German Botanical Society. Mikhail's surname "Цвет" means "color" in Russian, so there is the possibility that his naming the procedure chromatography (literally "color writing") was a way that he could make sure that he, a commoner in Tsarist Russia, could be immortalized.
In a 1903 lecture (published in 1905), Tsvet also described using filter paper to approximate the properties of living plant fibers in his experiments on plant pigments—a precursor to paper chromatography. He found that he could extract some pigments (such as orange carotenes and yellow xanthophylls) from leaves with non-polar solvents, but others (such as chlorophyll) required polar solvents. He reasoned that chlorophyll was held to the plant tissue by adsorption, and that stronger solvents were necessary to overcome the adsorption. To test this, he applied dissolved pigments to filter paper, allowed the solvent to evaporate, then applied different solvents to see which could extract the pigments from the filter paper. He found the same pattern as from leaf extractions: carotene could be extracted from filter paper using non-polar solvents, but chlorophyll required polar solvents.
Tsvet's work saw little use until the 1930s. | 1 | Applied and Interdisciplinary Chemistry |
In his inaugural lecture as professor of chemistry at University College London, Nyholm spoke of his concern for the teaching of chemistry. In 1957 Nyholm organized the first of an annual series of Summer Schools at University College on new aspects of chemical knowledge and theory, and demonstrations of new equipment. In the early sixties, the Nuffield Foundation, at least partly as a result of Nyholms influence, established the Science Teaching project, of which Nyholm was the first Chairman of the Chemistry Consultative Committee. This program led to the development of experiential GCE courses that emphasized the process of chemistry, rather than the recall of chemical facts, and explored the role of chemistry in society. In 1971 Nyholm published an article entitled Education for Change in which he differentiated between education and training as it applies to chemistry. He defined education as a process in which a person receives a training for a full life in a rapidly changing modern society, carried out in such a manner as will ensure the maximum development of the individual personality'. He was not a person who placed too much emphasis on fact-burdened and fact-tested learning such as in the National Curriculum developments in England in the nineteen-nineties.
Nyholm defined training for a full life as including:
# Recognition of oneself as an individual with the development of some kind of ethical standards. This may take place via training in religion of one kind or other; whether these beliefs are rejected later or not, they form at least a basis against which future behaviour can be measured.
# Man is a social being and needs to be made familiar with the nature of, and the reason for, the development of the society in which he is living
# Man needs to be able to communicate both by the spoken word and the written word
# Man must be numerate. It is essential that he receive an understanding of the process of quantitative thinking appropriate to his intellectual ability. | 0 | Theoretical and Fundamental Chemistry |
NPP catalyses the nucleophilic substitution of one ester bond on a phosphodiester substrate. It has a nucleoside binding pocket that excludes phospholipid substrates from the active site. A threonine nucleophile has been identified through site-directed mutagenesis, and the reaction inverts the stereochemistry of the phosphorus center. The sequence of bond breakage and formation has yet to be resolved. | 1 | Applied and Interdisciplinary Chemistry |
In organometallic chemistry, palladium-NHC complexes are a family of organopalladium compounds in which palladium forms a coordination complex with N-heterocyclic carbenes (NHCs). They have been investigated for applications in homogeneous catalysis,
particularly cross-coupling reactions. | 0 | Theoretical and Fundamental Chemistry |
Alternatives for normally occupied areas include (PFC-410 or CEA-410), CF (PFC-218 or CEA-308), HCFC Blend A (NAF S-III), HFC-23 (FE 13), HFC-227ea (FM 200), IG-01 (argon), IG-55 (argonite), HFC-125, or HFC-134a. For normally unoccupied areas, the alternatives include carbon dioxide, powdered Aerosol C, CFI, HCFC-22, HCFC-124, HFC-125, HFC-134a, gelled halocarbon/dry chemical suspension (PGA), blend of inert gas, high expansion foam systems and powdered aerosol (FS 0140), and IG-541 (Inergen).
Perfluorocarbons, i.e., PFCs such as CF, have very long atmospheric lifetimes and very high global warming potentials. Hydrochlorofluorocarbons, i.e., HCFCs including HCFC containing NAF S-III, contain chlorine and are stratospheric ozone layer depleters, although less so than Halon 1301. Their selection for usage as Halon replacements should consider those factors, and is restricted in some countries. | 1 | Applied and Interdisciplinary Chemistry |
Artificial seawater (abbreviated ASW) is a mixture of dissolved mineral salts (and sometimes vitamins) that simulates seawater. Artificial seawater is primarily used in marine biology and in marine and reef aquaria, and allows the easy preparation of media appropriate for marine organisms (including algae, bacteria, plants and animals). From a scientific perspective, artificial seawater has the advantage of reproducibility over natural seawater since it is a standardized formula. Artificial seawater is also known as synthetic seawater and substitute ocean water. | 0 | Theoretical and Fundamental Chemistry |
Seraj has established a well-equipped plant biotechnology laboratory at the University of Dhaka. She has been a co-principal investigator in several projects, such as the Generation Challenge Program (GCP)—an initiative to use molecular biology to help boost agricultural production.
Seraj has not only worked on fine mapping of the major QTLs for salinity tolerance in Pokkali, but also characterized traditional rice landraces with the aim of finding genetic loci responsible for salt tolerance and applying markers linked to these loci to aid breeding programs for incorporation of salinity tolerance in rice. She also works on developing genetically modified rice varieties with improved salt tolerance suitable for growing in the coastal region of Bangladesh. She was the recipient of the PEER award (joint USAID-NSF initiative) for using next generation sequencing technologies to find the basis of salt tolerance of a rice landrace endemic to the Bangladesh coast, where University of Texas at Austin served as the host for collaborative work.
Seraj has been a visiting scientist in [http://beta.irri.org/solutions/index.php?option=com_content&task=view&id=51&Itemid=69 PBGB, IRRI] (Constructs for salinity tolerance with Dr. John Bennett Jan-March 1998), PBGB & CSWS Division, IRRI (IRRI-PETRRA Bangladesh project on development of MV rice for the coastal wetlands of Bangladesh, June 11–29, 2002 and June 16–20, 2003), USDA research station at Beaumont, Texas, USA ( Aug. 4–16, 2003) and at the Department of Molecular, Cell and Developmental Biology, University of Texas, Austin, USA as Norman Borlaug Fellow (August 15-December 15, 2005). She has been honored with Visiting researcher status at University of Texas at Austin (October 2014-September, 2020). She was awarded the Annanya Award, 2017 for her scientific research. She was invited for a Tedx talk on how to save crops from sea level rise and salinity (Jan 16, 2018). She was featured in NHK TV, Japan in a talk on Science for Sustainable Earth in 2019. | 1 | Applied and Interdisciplinary Chemistry |
Before introduction of platinum catalysts by Speier, hydrosilylation was not practiced widely. A peroxide-catalyzed process was reported in academic literature in 1947, but the introduction of Speier's catalyst (HPtCl) was a big breakthrough.
Karstedts catalyst was later introduced. It is a lipophilic complex that is soluble in the organic substrates of industrial interest. Complexes and compounds that catalyze hydrogenation are often effective catalysts for hydrosilylation, e.g. Wilkinsons catalyst. | 0 | Theoretical and Fundamental Chemistry |
The NCI, headed by Dr. John R. Heller Jr., lobbied the United States Congress for financial support for second-generation chemotherapy research. In response, Congress created a Cancer Chemotherapy National Service Center (CCNSC) at the NCI in 1955. This was the first federal programme to promote drug discovery for cancer – unlike now, most pharmaceutical companies were not yet interested in developing anticancer drugs. The CCNSC developed the methodologies and crucial tools (like cell lines and animal models) for chemotherapeutic development. | 1 | Applied and Interdisciplinary Chemistry |
Semiconductor detectors, also called solid-state detectors, are fundamentally different from scintillation detectors: They rely on detection of the charge carriers (electrons and holes) generated in semiconductors by energy deposited by gamma ray photons.
In semiconductor detectors, an electric field is applied to the detector volume. An electron in the semiconductor is fixed in its valence band in the crystal until a gamma ray interaction provides the electron enough energy to move to the conduction band. Electrons in the conduction band can respond to the electric field in the detector, and therefore move to the positive contact that is creating the electrical field. The gap created by the moving electron is called a "hole", and is filled by an adjacent electron. This shuffling of holes effectively moves a positive charge to the negative contact. The arrival of the electron at the positive contact and the hole at the negative contact produces the electrical signal that is sent to the preamplifier, the MCA, and on through the system for analysis. The movement of electrons and holes in a solid-state detector is very similar to the movement of ions within the sensitive volume of gas-filled detectors such as ionization chambers.
Common semiconductor-based detectors include germanium, cadmium telluride, and cadmium zinc telluride.
Germanium detectors provide significantly improved energy resolution in comparison to sodium iodide detectors, as explained in the preceding discussion of resolution. Germanium detectors produce the highest resolution commonly available today. However, a disadvantage is the requirement of cryogenic temperatures for the operation of germanium detectors, typically by cooling with liquid nitrogen. | 0 | Theoretical and Fundamental Chemistry |
Most of the iron in the body is hoarded and recycled by the reticuloendothelial system, which breaks down aged red blood cells. In contrast to iron uptake and recycling, there is no physiologic regulatory mechanism for excreting iron. People lose a small but steady amount by gastrointestinal blood loss, sweating and by shedding cells of the skin and the mucosal lining of the gastrointestinal tract. The total amount of loss for healthy people in the developed world amounts to an estimated average of a day for men, and 1.5–2 mg a day for women with regular menstrual periods. People with gastrointestinal parasitic infections, more commonly found in developing countries, often lose more. Those who cannot regulate absorption well enough get disorders of iron overload. In these diseases, the toxicity of iron starts overwhelming the body's ability to bind and store it. | 1 | Applied and Interdisciplinary Chemistry |
The Lamberhurst Foundry is believed to have been the maker in 1710–14 of some of the earliest cast-iron railings produced in England, which they made for St Paul's Cathedral, despite the objections of Christopher Wren, who did not want a fence around the Cathedral at all, and said that if there had to be one it should be of wrought rather than cast iron. The railings surrounded the cathedral, including seven gates. It weighed two hundred tons and cost six pence a pound. The total cost was £11,202. No further railings are known to have been cast in the Weald. Other early uses of cast iron railings were at Cambridge Senate House and at St Martin-in-the-Fields, London. | 1 | Applied and Interdisciplinary Chemistry |
The Chapman approach has been applied in a variety of ways since its original report, varying substrates, oxidants, and other aspects (and so synthesis of carpanone has subsequently been achieved by "quite a few research groups"); the actual mechanism of Pd(II) action is likely more complex than the original conjecture, and there is evidence that the mechanism, broadly speaking, depends on actual conditions (specific substrate, oxidant, etc.). Various groups, including the laboratories of Steve Ley, Craig Lindley, and Matthew Shair, have succeeded in extending the Chapman method to solid-supported synthesis, i.e., phenolic starting materials on polymeric supports, thus allowing the generation of libraries of carpanone analogs. A hetero-8-8' oxidative coupling system akin to the Chapman approach has been developed that uses IPh(OAC), and that allows for preparation of more electron rich homodimers, and for hetero-tetracyclic analogs of carpanone. | 0 | Theoretical and Fundamental Chemistry |
The US Food and Drug Administration issued a Premarket Submission and Labeling Recommendations for Drugs of Abuse Screening Tests. Its availability was announced in the Federal Register, Vol. 68, No. 231 on December 2, 2003 and is listed under "Notices." Presumptive testing has found widespread use by employers and public entities. Most people who take a drug test take a presumptive test, cheaper and faster than other methods of testing. However, it is less accurate and can render false results. The FDA recommends for confirmatory testing to be conducted and the placing of a warning label on the presumptive drug test: "This assay provides only a preliminary result. Clinical consideration and professional judgment should be applied to any drug of abuse test result, in evaluating a preliminary positive result. To obtain a confirmed analytical result, a more specific alternate chemical method is needed. Gas chromatography/mass spectrometry (GC/MS) is the recommended confirmatory method." | 0 | Theoretical and Fundamental Chemistry |
The Surface Force Apparatus (SFA) is a scientific instrument which measures the interaction force of two surfaces as they are brought together and retracted using multiple beam interferometry to monitor surface separation and directly measure contact area and observe any surface deformations occurring in the contact zone. One surface is held by a cantilevered spring, and the deflection of the spring is used to calculate the force being exerted. The technique was pioneered by David Tabor and R.H.S. Winterton in the late 1960s at Cambridge University. By the mid-1970s, J.N. Israelachvili had adapted the original design to operate in liquids, notably aqueous solutions, while at the Australian National University, and further advanced the technique to support friction and electro-chemical surface studies while at the University of California Santa Barbara. | 0 | Theoretical and Fundamental Chemistry |
* Oxime compounds are used as antidotes for nerve agents. A nerve agent inactivates acetylcholinesterase by phosphorylation. Oxime compounds can reactivate acetylcholinesterase by attaching to phosphorus, forming an oxime-phosphonate, which then splits away from the acetylcholinesterase molecule. Oxime nerve-agent antidotes are pralidoxime (also known as 2-PAM), obidoxime, methoxime, HI-6, Hlo-7, and TMB-4. The effectiveness of the oxime treatment depends on the particular nerve agent used.
* Perillartine, the oxime of perillaldehyde, is used as an artificial sweetener in Japan. It is 2000 times sweeter than sucrose.
* Diaminoglyoxime is a key precursor to various compounds containing the highly reactive furazan ring.
* Methyl ethyl ketoxime is a skin-preventing additive in many oil-based paints.
* Buccoxime and 5-methyl-3-heptanone oxime ("Stemone") are perfume ingredients.
*Fluvoxamine is used as an antidepressant. | 0 | Theoretical and Fundamental Chemistry |
The somatic fusion process occurs in four steps:
# The removal of the cell wall of one cell of each type of plant using cellulase enzyme to produce a somatic cell called a protoplast
# The cells are then fused using electric shock (electrofusion) or chemical treatment to join the cells and fuse together the nuclei. The resulting fused nucleus is called heterokaryon.
# The formation of the cell wall is then induced using hormones
# The cells are then grown into calluses which then are further grown to plantlets and finally to a full plant, known as a somatic hybrid.
The procedure for seed plants describe above, fusion of moss protoplasts can be initiated without electric shock but by the use of polyethylene glycol (PEG). Further, moss protoplasts do not need phytohormones for regeneration, and they do not form a callus. Instead, regenerating moss protoplasts behave like germinating moss spores. Of further note sodium nitrate and calcium ion at high pH can be used, although results are variable depending on the organism. | 1 | Applied and Interdisciplinary Chemistry |
Evidence from an expert who has compared DNA samples must be accompanied by evidence as to the sources of the samples and the procedures for obtaining the DNA profiles. The judge must ensure that the jury must understand the significance of DNA matches and mismatches in the profiles. The judge must also ensure that the jury does not confuse the match probability (the probability that a person that is chosen at random has a matching DNA profile to the sample from the scene) with the probability that a person with matching DNA committed the crime. In 1996 R v. Doheny
Juries should weigh up conflicting and corroborative evidence, using their own common sense and not by using mathematical formulae, such as Bayes' theorem, so as to avoid "confusion, misunderstanding and misjudgment". | 1 | Applied and Interdisciplinary Chemistry |
It is important to consider the downstream applications of the plasmid DNA when choosing a purification method. For example, if the plasmid is to be used for transfection or electroporation, a purification method that results in high purity and low endotoxin levels is desirable. Similarly, if the plasmid is to be used for sequencing or PCR, a purification method that results in high yield and minimal contaminants is desirable. However, multiple methods of nucleic acid purification exist. All work on the principle of generating conditions where either only the nucleic acid precipitates, or only other biomolecules precipitate, allowing the nucleic acid to be separated. | 1 | Applied and Interdisciplinary Chemistry |
Near the corner, the flow can be assumed to be Stokes flow. Describing the two-dimensional planar problem by the cylindrical coordinates with velocity components defined by a stream function such that
the governing equation can be shown to be simply the biharmonic equation . The equation has to be solved with homogeneous boundary conditions (conditions taken for two walls separated by angle )
The Taylor scraping flow is similar to this problem but driven inhomogeneous boundary condition. The solution is obtained by the eigenfunction expansion,
where are constants and the real part of the eigenvalues are always greater than unity. The eigenvalues will be function of the angle , but regardless eigenfunctions can be written down for any ,
For antisymmetrical solution, the eigenfunction is even and hence and the boundary conditions demand . The equations admits no real root when °. These complex eigenvalues indeed correspond to the moffatt eddies. The complex eigenvalue if given by where
Here . | 1 | Applied and Interdisciplinary Chemistry |
is a Japanese chemist. He won the Nobel Prize in Chemistry in 2001, Noyori shared a half of the prize with William S. Knowles for the study of chirally catalyzed hydrogenations; the second half of the prize went to K. Barry Sharpless for his study in chirally catalyzed oxidation reactions (Sharpless epoxidation). | 0 | Theoretical and Fundamental Chemistry |
Raw water (untreated) is from a surface water source (such as an intake on a lake or a river) or from a groundwater source (such as a water well drawing from an underground aquifer) within the watershed that provides the water resource.
The raw water is transferred to the water purification facilities using uncovered aqueducts, covered tunnels or underground water pipes. | 1 | Applied and Interdisciplinary Chemistry |
Nanocomposite hydrogels are observed to be temperature sensitive and will change temperature when their surrounding is altered. Inorganic salts, when absorbed, will result in changing the hydrogels to a lower temperature whereas cat-ionic surfactant will shift the temperature the other way. The temperature of these hydrogels are around 40 degrees Celsius, making it a possible candidate for use as biomaterial. The stimulus-sensitivity of hydrogels allow for a responsive release system where the hydrogels can be designed to deliver the drug in response to changes in condition of the body. | 0 | Theoretical and Fundamental Chemistry |
In the iron–carbon system (i.e. plain-carbon steels and cast irons) it is a common constituent because ferrite can contain at most 0.02wt% of uncombined carbon. Therefore, in carbon steels and cast irons that are slowly cooled, a portion of the carbon is in the form of cementite. Cementite forms directly from the melt in the case of white cast iron. In carbon steel, cementite precipitates from austenite as austenite transforms to ferrite on slow cooling, or from martensite during tempering. An intimate mixture with ferrite, the other product of austenite, forms a lamellar structure called pearlite.
While cementite is thermodynamically unstable, eventually being converted to austenite (low carbon level) and graphite (high carbon level) at higher temperatures, it does not decompose on heating at temperatures below the eutectoid temperature (723 °C) on the metastable iron-carbon phase diagram.
Mechanical properties are as follows: room temperature microhardness 760–1350 HV; bending strength 4.6–8 GPa, Young's modulus 160–180 GPa, indentation fracture toughness 1.5–2.7 MPa√m. | 1 | Applied and Interdisciplinary Chemistry |
Mach number, a useful quantity in aerodynamics, is the ratio of air speed to the local speed of sound. At altitude, for reasons explained, Mach number is a function of temperature.
Aircraft flight instruments, however, operate using pressure differential to compute Mach number, not temperature. The assumption is that a particular pressure represents a particular altitude and, therefore, a standard temperature. Aircraft flight instruments need to operate this way because the stagnation pressure sensed by a Pitot tube is dependent on altitude as well as speed. | 1 | Applied and Interdisciplinary Chemistry |
The Chesapeake Bay forms a link in the Intracoastal Waterway, of the bays, sounds and inlets between the off-shore barrier islands and the coastal mainland along the Atlantic coast connecting the Chesapeake and Delaware Canal (linking the Bay to the north and the Delaware River) with the Albemarle and Chesapeake Canal (linking the Bay, to the south, via the Elizabeth River, by the cities of Norfolk and Portsmouth to the Albemarle Sound and Pamlico Sound in North Carolina and further to the Sea Islands of Georgia). A busy shipping channel (dredged by the U.S. Army Corps of Engineers since the 1850s) runs the length of the Bay, is an important transit route for large vessels entering or leaving the Port of Baltimore, and further north through the Chesapeake and Delaware Canal to the ports of Wilmington and Philadelphia on the Delaware River.
During the later half of the 19th century and the first half of the 20th century, the Bay was plied by passenger steamships and packet boat lines connecting the various cities on it, notably the Baltimore Steam Packet Company ("Old Bay Line").
In the later 20th century, a series of road crossings were built. One, the Chesapeake Bay Bridge (also known as the Governor William Preston Lane, Jr. Memorial Bridge) between the state capital of Annapolis, Maryland and Matapeake on the Eastern Shore, crossing Kent Island, was constructed 1949–1952. A second, parallel, span was added in 1973. The Chesapeake Bay Bridge–Tunnel, connecting Virginia's Eastern Shore with its mainland (at the metropolitan areas of Virginia Beach, Norfolk, Portsmouth, and Chesapeake), is approximately long; it has trestle bridges as well as two stretches of tunnels that allow unimpeded shipping; the bridge is supported by four man-made islands. The Chesapeake Bay Bridge–Tunnel was opened for two lanes in 1964 and four lanes in 1999. | 1 | Applied and Interdisciplinary Chemistry |
The CDP (formerly the Carbon Disclosure Project) is an international non-profit organisation based in the United Kingdom, Japan, India, China, Germany, Brazil and the United States that helps companies, cities, states, regions and public authorities disclose their environmental impact. It aims to make environmental reporting and risk management a business norm, driving disclosure, insight, and action towards a sustainable economy. In 2022, nearly 18,700 organizations disclosed their environmental information through CDP. | 1 | Applied and Interdisciplinary Chemistry |
Multiple bismuth-containing clusters were reported, some of them synthesized through carbon monoxide ligand loss from the previously reported bismuth complexes. Strained cluster complexes with monodentate as well as bridging carbon monoxide units have also been isolated, such as [{Cp(μ-CO)Fe}(μ-Bi)] and [(µ-Bi)Co(CO)(µ-CO)].
Spiro-like clusters such as [{Ru(CO)}(µ-Bi){(µ-H)Ru(CO)} and cubane-like ones as [BiCo*] are representatives as well. The former displays a tetracoordinate bismuth metallic center along with a dicoordinated hydride ligand. The structure of the latter is cubic with the edges alternating bismuth and cobalt metallic centers. | 0 | Theoretical and Fundamental Chemistry |
Dynabeads are superparamagnetic spherical polymer particles with a uniform size and a consistent, defined surface for the adsorption or coupling of various bioreactive molecules or cells. | 0 | Theoretical and Fundamental Chemistry |
In carbon fixation, plants convert carbon dioxide into sugars, from which many biosynthetic pathways originate. The catalyst responsible for this conversion, RuBisCO, is the most common protein. Some anaerobic organisms employ enzymes to convert CO to carbon monoxide, from which fatty acids can be made.
In industry, a few products are made from CO, including urea, salicylic acid, methanol, and certain inorganic and organic carbonates. In the laboratory, carbon dioxide is sometimes used to prepare carboxylic acids in a process known as carboxylation. An electrochemical CO electrolyzer that operates at room temperature has not yet been commercialized. Elevated temperature solid oxide electrolyzer cells (SOECs) for CO reduction to CO are commercially available. For example, Haldor Topsoe offers SOECs for CO reduction with a reported 6-8 kWh per Nm CO produced and purity up to 99.999% CO. | 1 | Applied and Interdisciplinary Chemistry |
One variation is called the decarboxylative A coupling. In this reaction the amine is replaced by an amino acid. The imine can isomerise and the alkyne group is placed at the other available nitrogen alpha position. This reaction requires a copper catalyst. The redox A coupling has the same product outcome but the reactants are again an aldehyde, an amine and an alkyne as in the regular A coupling. | 0 | Theoretical and Fundamental Chemistry |
Mechanically, NbSn is extremely brittle and thus cannot be easily drawn into a wire, which is necessary for winding superconducting magnets. To overcome this, wire manufacturers typically draw down composite wires containing ductile precursors. The "internal tin" process includes separate alloys of Nb, Cu and Sn. The "bronze" process contains Nb in a copper–tin bronze matrix. With both processes the strand is typically drawn to final size and coiled into a solenoid or cable before heat treatment. It is only during heat treatment that the Sn reacts with the Nb to form the brittle, superconducting niobium–tin compound. The powder-in-tube process is also used.
The high field section of modern NMR magnets are composed of niobium–tin wire. | 1 | Applied and Interdisciplinary Chemistry |
A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical synthesis (both semisynthesis and total synthesis) and have played a central role in the development of the field of organic chemistry by providing challenging synthetic targets. The term natural product has also been extended for commercial purposes to refer to cosmetics, dietary supplements, and foods produced from natural sources without added artificial ingredients.
Within the field of organic chemistry, the definition of natural products is usually restricted to organic compounds isolated from natural sources that are produced by the pathways of secondary metabolism. Within the field of medicinal chemistry, the definition is often further restricted to secondary metabolites. Secondary metabolites (or specialized metabolites) are not essential for survival, but nevertheless provide organisms that produce them an evolutionary advantage. Many secondary metabolites are cytotoxic and have been selected and optimized through evolution for use as "chemical warfare" agents against prey, predators, and competing organisms. Secondary or specialized metabolites are often unique to species, which is contrasted to primary metabolites which have broad use across kingdoms. Secondary metabolites are marked by chemical complexity which is why they are of such interest to chemists.
Natural sources may lead to basic research on potential bioactive components for commercial development as lead compounds in drug discovery. Although natural products have inspired numerous drugs, drug development from natural sources has received declining attention in the 21st century by pharmaceutical companies, partly due to unreliable access and supply, intellectual property, cost, and profit concerns, seasonal or environmental variability of composition, and loss of sources due to rising extinction rates. | 1 | Applied and Interdisciplinary Chemistry |
In biochemistry, dephosphorylation is the removal of a phosphate (PO) group from an organic compound by hydrolysis. It is a reversible post-translational modification. Dephosphorylation and its counterpart, phosphorylation, activate and deactivate enzymes by detaching or attaching phosphoric esters and anhydrides. A notable occurrence of dephosphorylation is the conversion of ATP to ADP and inorganic phosphate.
Dephosphorylation employs a type of hydrolytic enzyme, or hydrolase, which cleaves ester bonds. The prominent hydrolase subclass used in dephosphorylation is phosphatase, which removes phosphate groups by hydrolysing phosphoric acid monoesters into a phosphate ion and a molecule with a free hydroxyl (-OH) group.
The reversible phosphorylation-dephosphorylation reaction occurs in every physiological process, making proper function of protein phosphatases necessary for organism viability. Because protein dephosphorylation is a key process involved in cell signalling, protein phosphatases are implicated in conditions such as cardiac disease, diabetes, and Alzheimer's disease. | 1 | Applied and Interdisciplinary Chemistry |
Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. Nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus of an atom is changed.
A transmutation can be achieved either by nuclear reactions (in which an outside particle reacts with a nucleus) or by radioactive decay, where no outside cause is needed.
Natural transmutation by stellar nucleosynthesis in the past created most of the heavier chemical elements in the known existing universe, and continues to take place to this day, creating the vast majority of the most common elements in the universe, including helium, oxygen and carbon. Most stars carry out transmutation through fusion reactions involving hydrogen and helium, while much larger stars are also capable of fusing heavier elements up to iron late in their evolution.
Elements heavier than iron, such as gold or lead, are created through elemental transmutations that can naturally occur in supernovae. One goal of alchemy, the transmutation of base substances into gold, is now known to be impossible by chemical means but possible by physical means. As stars begin to fuse heavier elements, substantially less energy is released from each fusion reaction. This continues until it reaches iron which is produced by an endothermic reaction consuming energy. No heavier element can be produced in such conditions.
One type of natural transmutation observable in the present occurs when certain radioactive elements present in nature spontaneously decay by a process that causes transmutation, such as alpha or beta decay. An example is the natural decay of potassium-40 to argon-40, which forms most of the argon in the air. Also on Earth, natural transmutations from the different mechanisms of natural nuclear reactions occur, due to cosmic ray bombardment of elements (for example, to form carbon-14), and also occasionally from natural neutron bombardment (for example, see natural nuclear fission reactor).
Artificial transmutation may occur in machinery that has enough energy to cause changes in the nuclear structure of the elements. Such machines include particle accelerators and tokamak reactors. Conventional fission power reactors also cause artificial transmutation, not from the power of the machine, but by exposing elements to neutrons produced by fission from an artificially produced nuclear chain reaction. For instance, when a uranium atom is bombarded with slow neutrons, fission takes place. This releases, on average, three neutrons and a large amount of energy. The released neutrons then cause fission of other uranium atoms, until all of the available uranium is exhausted. This is called a chain reaction.
Artificial nuclear transmutation has been considered as a possible mechanism for reducing the volume and hazard of radioactive waste. | 0 | Theoretical and Fundamental Chemistry |
Ultraviolet disinfection of water is a purely physical, chemical-free process. Even parasites such as Cryptosporidium or Giardia, which are extremely resistant to chemical disinfectants, are efficiently reduced. UV can also be used to remove chlorine and chloramine species from water; this process is called photolysis, and requires a higher dose than normal disinfection. The dead microorganisms are not removed from the water. UV disinfection does not remove dissolved organics, inorganic compounds or particles in the water. The world's largest water disinfection plant treats drinking water for New York City. The Catskill-Delaware Water Ultraviolet Disinfection Facility, commissioned on 8 October 2013, incorporates a total of 56 energy-efficient UV reactors treating up to a day.
Ultraviolet can also be combined with ozone or hydrogen peroxide to produce hydroxyl radicals to break down trace contaminants through an advanced oxidation process.
It used to be thought that UV disinfection was more effective for bacteria and viruses, which have more-exposed genetic material, than for larger pathogens that have outer coatings or that form cyst states (e.g., Giardia) that shield their DNA from UV light. However, it was recently discovered that ultraviolet radiation can be somewhat effective for treating the microorganism Cryptosporidium. The findings resulted in the use of UV radiation as a viable method to treat drinking water. Giardia in turn has been shown to be very susceptible to UV-C when the tests were based on infectivity rather than excystation. It has been found that protists are able to survive high UV-C doses but are sterilized at low doses. | 0 | Theoretical and Fundamental Chemistry |
In chemistry and thermodynamics, the enthalpy of neutralization () is the change in enthalpy that occurs when one equivalent of an acid and a base undergo a neutralization reaction to form water and a salt. It is a special case of the enthalpy of reaction. It is defined as the energy released with the formation of 1 mole of water.
When a reaction is carried out under standard conditions at the temperature of 298 K (25 degrees Celsius) and 1 atm of pressure and one mole of water is formed, the heat released by the reaction is called the standard enthalpy of neutralization ().
The heat () released during a reaction is
where is the mass of the solution, is the specific heat capacity of the solution, and is the temperature change observed during the reaction. From this, the standard enthalpy change () is obtained by division with the amount of substance (in moles) involved.
When a strong acid, HA, reacts with a strong base, BOH, the reaction that occurs is
as the acid and the base are fully dissociated and neither the cation nor the anion are involved in the neutralization reaction. The enthalpy change for this reaction is -57.62 kJ/mol at 25 °C.
For weak acids or bases, the heat of neutralization is pH-dependent. In the absence of any added mineral acid or alkali, some heat is required for complete dissociation. The total heat evolved during neutralization will be smaller.
:e.g. at 25°C
The heat of ionization for this reaction is equal to (–12 + 57.3) = 45.3 kJ/mol at 25 °C. | 0 | Theoretical and Fundamental Chemistry |
There are various forms of mutations that can occur in coding regions. One form is silent mutations, in which a change in nucleotides does not result in any change in amino acid after transcription and translation. There also exist nonsense mutations, where base alterations in the coding region code for a premature stop codon, producing a shorter final protein. Point mutations, or single base pair changes in the coding region, that code for different amino acids during translation, are called missense mutations. Other types of mutations include frameshift mutations such as insertions or deletions. | 1 | Applied and Interdisciplinary Chemistry |
The effect was described by Louis Pasteur in 1857 in experiments showing that aeration of yeasted broth causes cell growth to increase while the fermentation rate decreases, based on lowered ethanol production. | 1 | Applied and Interdisciplinary Chemistry |
The gallbladder is a hollow part of the biliary tract that sits just beneath the liver, with the gallbladder body resting in a small depression. It is a small organ where the bile produced by the liver is stored, before being released into the small intestine. Bile flows from the liver through the bile ducts and into the gall bladder for storage. The bile is released in response to cholecystokinin (CCK), a peptide hormone released from the duodenum. The production of CCK (by endocrine cells of the duodenum) is stimulated by the presence of fat in the duodenum.
It is divided into three sections, a fundus, body and neck. The neck tapers and connects to the biliary tract via the cystic duct, which then joins the common hepatic duct to form the common bile duct. At this junction is a mucosal fold called Hartmanns pouch, where gallstones commonly get stuck. The muscular layer of the body is of smooth muscle tissue that helps the gallbladder contract, so that it can discharge its bile into the bile duct. The gallbladder needs to store bile in a natural, semi-liquid form at all times. Hydrogen ions secreted from the inner lining of the gallbladder keep the bile acidic enough to prevent hardening. To dilute the bile, water and electrolytes from the digestion system are added. Also, salts attach themselves to cholesterol molecules in the bile to keep them from crystallising. If there is too much cholesterol or bilirubin in the bile, or if the gallbladder does not empty properly the systems can fail. This is how gallstones form when a small piece of calcium gets coated with either cholesterol or bilirubin and the bile crystallises and forms a gallstone. The main purpose of the gallbladder is to store and release bile, or gall'. Bile is released into the small intestine in order to help in the digestion of fats by breaking down larger molecules into smaller ones. After the fat is absorbed, the bile is also absorbed and transported back to the liver for reuse. | 1 | Applied and Interdisciplinary Chemistry |
Nanoscale iron can be directly into the subsurface because they are small enough to be distributed thoroughly. Because the particles are so small, they have a comparatively large reactive surface, providing a more effective reaction. As of now, nanoscale iron is the only material that has been used with this injection strategy, and it is probably the only material that is effective in injection. | 1 | Applied and Interdisciplinary Chemistry |
Proteolysis-targeting chimeras (PROTACs) were first reported by Kathleen Sakamoto, Craig Crews, and Raymond Deshaies in 2001. A chimeric molecule consisting of ovalicin (a MetAP-2 small molecule inhibitor) and IκBα phosphopeptide (a recruiter of the SCFβ-TRCP E3 ligase complex) separated by a linker was constructed and shown to induce MetAP-2 degradation in in vitro cell models. Further study confirmed that E3 ligase-mediated ubiquitination and subsequent proteasome degradation was responsible for reduced MetAP-2 levels. Continued work on this system by Craig Crews and others has expanded the potential pool of E3 ligases and degradation targets with Arvinas Inc. founded in 2013 to bring PROTAC drugs to market. As of April 2023, Arvinas has one drug in Stage 3 clinical trials (ARV-471, an estrogen receptor degrader), and two drugs in Stage 2 clinical trials (androgen receptor degraders ARV-110 and ARV-766) for treatment of breast and prostate cancer, respectively. Arvinas released Phase 2 clinical trial results for ARV-471 in December, 2022 reporting a clinical benefit rate of 40% in CDK4/6 inhibitor-pretreated patients and an absence of dose-limiting toxicities. | 1 | Applied and Interdisciplinary Chemistry |
Before his famous doctoral studies on magnetism, he designed and perfected an extremely sensitive torsion balance for measuring magnetic coefficients. Variations on this equipment were commonly used by future workers in that area. Pierre Curie studied ferromagnetism, paramagnetism, and diamagnetism for his doctoral thesis, and discovered the effect of temperature on paramagnetism which is now known as Curies law. The material constant in Curies law is known as the Curie constant. He also discovered that ferromagnetic substances exhibited a critical temperature transition, above which the substances lost their ferromagnetic behavior. This is now known as the Curie temperature. The Curie temperature is used to study plate tectonics, treat hypothermia, measure caffeine, and to understand extraterrestrial magnetic fields. The Curie is a unit of measurement (3.7 × 10 decays per second or 37 gigabecquerels) used to describe the intensity of a sample of radioactive material and was named after Marie and Pierre Curie by the Radiology Congress in 1910.
Pierre Curie formulated what is now known as the Curie Dissymmetry Principle: a physical effect cannot have a dissymmetry absent from its efficient cause. For example, a random mixture of sand in zero gravity has no dissymmetry (it is isotropic). Introduce a gravitational field, and there is a dissymmetry because of the direction of the field. Then the sand grains can self-sort with the density increasing with depth. But this new arrangement, with the directional arrangement of sand grains, actually reflects the dissymmetry of the gravitational field that causes the separation.
Curie worked with his wife in isolating polonium and radium. They were the first to use the term "radioactivity", and were pioneers in its study. Their work, including Marie Curies celebrated doctoral work, made use of a sensitive piezoelectric electrometer constructed by Pierre and his brother Jacques Curie. Pierre Curies 26 December 1898 publication with his wife and M. G. Bémont for their discovery of radium and polonium was honored by a Citation for Chemical Breakthrough Award from the Division of History of Chemistry of the American Chemical Society presented to the ESPCI ParisTech (officially the École supérieure de physique et de Chimie industrielles de la Ville de Paris) in 2015. In 1903, to honor the Curies' work, the Royal Society of London invited Pierre to present their research. Marie Curie was not permitted to give the lecture so Lord Kelvin sat beside her while Pierre spoke on their research. After this, Lord Kelvin held a luncheon for Pierre. While in London, Pierre and Marie were awarded the Davy Medal of the Royal Society of London. In the same year, Pierre and Marie Curie, as well as Henri Becquerel, were awarded a Nobel Prize in physics for their research of radioactivity.
Curie and one of his students, Albert Laborde, made the first discovery of nuclear energy, by identifying the continuous emission of heat from radium particles. Curie also investigated the radiation emissions of radioactive substances, and through the use of magnetic fields was able to show that some of the emissions were positively charged, some were negative and some were neutral. These correspond to alpha, beta and gamma radiation. | 1 | Applied and Interdisciplinary Chemistry |
The main application of DVS is to measure water sorption isotherms. In general, a vapor sorption isotherm shows the equilibrium amount of vapor sorbed as a function of steady state relative vapor pressure at a constant temperature. For water sorption isotherms, water-relative vapor pressure is more commonly expressed as relative humidity. This is accomplished in a DVS measurement by exposing a sample to a series of step changes in relative humidity and monitoring the mass change as a function of time. The sample mass must be allowed to reach gravimetric equilibrium at each step change in humidity before progressing to the next humidity level. Then, the equilibrium mass values at each relative humidity step are used to generate the isotherm. Isotherms are typically divided into two components: sorption for increasing humidity steps, and desorption for decreasing humidity steps. Sorption can be further divided into adsorption (sorbate located on the surface) and absorption (sorbate penetrates the bulk). | 0 | Theoretical and Fundamental Chemistry |
Copper has played a role in architecture for thousands of years. For example, in ancient Egypt, massive doors to the temple of Amen-Re at Karnak were clad with copper. In the 3rd Century B.C., copper roof shingles were installed atop of the Lowa Maha Paya Temple in Sri Lanka. And the Romans used copper as roof covering for the Pantheon in 27 B.C.
Centuries later, copper and its alloys were integral in medieval architecture. The doors of the Church of the Nativity at Bethlehem (6th century) are covered with plates of bronze, cut out in patterns. Those of Hagia Sophia at Constantinople, of the 8th and 9th century, are wrought in bronze. Bronze doors on the Aachen Cathedral in Germany date back to about 800 A.D. Bronze baptistery doors at the Cathedral of Florence were completed in 1423 A.D. by Ghiberti.
The copper roof of Hildesheim Cathedral, installed in 1280 A.D., survives to this day. And the roof at Kronborg, one of northern Europes most important Renaissance castles that was immortalized as Elsinore Castle in Shakespeares Hamlet, was installed in 1585 A.D. The copper on the tower was renovated in 2009.
For years, copper was reserved mainly for public institutions, such as churches, government buildings, and universities. Copper roofs are often one of the most architecturally distinguishable features of these structures.
Today, architectural copper is used in roofing systems, flashings and copings, rain gutters and downspouts, building expansion joints, wall cladding, domes, spires, vaults, and various other design elements. Simultaneously, the metal has evolved from a weather barrier and exterior design element into indoor building environments where it is changing the way commercial and residential interiors are decorated.
In the 21st century, the use of copper continues to evolve in the indoor environment. Its recently proven antimicrobial properties reduce pathogenic bacterial loads on such products as handrails, bedrails, bathroom fixtures, counter tops, etc. These antimicrobial copper-based products are now being incorporated into public facilities (hospitals, nursing homes, mass transit facilities) as well as in residential buildings because of the public health benefits. (For main article, see: Antimicrobial copper-alloy touch surfaces.) | 1 | Applied and Interdisciplinary Chemistry |
The 2nd group of anions consist of Cl, Br, I, NO and CO. The group reagent for Group 2 anion is concentrated sulfuric acid (HSO).
After addition of the acid, chlorides, bromides and iodides will form precipitates with silver nitrate. The precipitates are white, pale yellow, and yellow, respectively. The silver halides formed are completely soluble, partially soluble, or not soluble at all, respectively, in aqueous ammonia solution.
Chlorides are confirmed by the chromyl chloride test. When the salt is heated with KCrO and concentrated HSO, red vapours of chromyl chloride (CrOCl) are produced. Passing this gas through a solution of NaOH produces a yellow solution of NaCrO. The acidified solution of NaCrO gives a yellow precipitate with the addition of (CHCOO)Pb.
Bromides and iodides are confirmed by the layer test. A sodium carbonate extract is made from the solution containing bromide or iodide, and CHCl or carbon disulfide| is added to the solution, which separates into two layers: an orange colour in the or layer indicates the presence of Br, and a violet colour indicates the presence of I.
Nitrates give brown fumes with concentrated HSO due to formation of NO. This is intensified upon adding copper turnings. Nitrate ion is confirmed by adding an aqueous solution of the salt to FeSO and pouring concentrated HSO slowly along the sides of the test tube, which produces a brown ring around the walls of the tube, at the junction of the two liquids caused by the formation of .
Upon treatment with concentrated sulfuric acid, oxalates yield colourless CO and CO gases. These gases burn with a bluish flame and turn lime water milky. Oxalates also decolourise KMnO and give a white precipitate with CaCl. | 0 | Theoretical and Fundamental Chemistry |
Contraindications include:
* Pregnancy
* Impaired renal and liver function
* Patients with a history of angioedema related to previous treatment with an ACE inhibitor
* Hypersensitivity to Quinapril | 0 | Theoretical and Fundamental Chemistry |
Karl Söllner (9 January 1903 – 14 June 1986) was an Austrian-American chemist, primarily active in the field of physical chemistry and biophysics. | 0 | Theoretical and Fundamental Chemistry |
N-Arylcinnamides have emerged as potent and important class of TRPV1 antagonists, Compound SB-366791, (fig. 6a) shows competitive and specific activity in both human and rat TRPV1 receptors overall profile of receptor selectivity much better than that of capsazepine.
Within this series of compounds, AMG-9810 (fig. 6b) exhibited high antagonist potency showing good oral bio-availability in rats and a promising pharmacokinetic profile, boding well for clinical efficacy. Another potent blocker from this group is AMG0347(fig. 6c)that was shown in a postoperative pain trial to be able to decrease capsaicin-induced heat and mechanical hyperalgesia and to block central TRPV1 receptors. | 1 | Applied and Interdisciplinary Chemistry |
Supercritical liquid–gas boundaries are lines in the pressure-temperature (pT) diagram that delimit more liquid-like and more gas-like states of a supercritical fluid. They comprise the Fisher–Widom line, the Widom line, and the Frenkel line. | 0 | Theoretical and Fundamental Chemistry |
The problem on the whole is similar to the one dimensional heat conduction problem. Hence a self-similar variable can be introduced
Substituting this the partial differential equation, reduces it to ordinary differential equation
with boundary conditions
The solution to the above problem can be written in terms of complementary error function
The force per unit area exerted on the plate is | 1 | Applied and Interdisciplinary Chemistry |
In addition to monitoring oil contamination and wear metals, modern usage of OA includes the analysis of the additives in oils to determine if an extended drain interval may be used. Maintenance costs can be reduced using OA to determine the remaining useful life of additives in the oil. By comparing the OA results of new and used oil, a tribologist can determine when an oil must be replaced. Careful analysis might even allow the oil to be "sweetened" to its original additive levels by either adding fresh oil or replenishing additives that were depleted.
Oil analysis professionals and analysts can get certified in compliance with ISO standards by passing exams administered by the International Council for Machinery Lubrication (ICML).
For purposes of Oil Analysis Program (OAP) trend analysis, replacement, replenishment or drain and flush of lubricating fluids in excess of half an engine’s oil capacity (2.5 gallons or more) will be considered an Oil Change and the engine will be placed in code Charlie (C) for three flights to establish a new working trend. Oil-Wetted Maintenance (OWM) is any replacement of engine components within an oil-lubricated system (bearings, gearbox, pumps, etc.). OWM actions shall be documented on DD Form 2026 and submitted to OAP lab for update of Oil Analysis database.
(a) Special Samples can be requested by the laboratory whenever they feel its necessary.
(b) Whenever directed by the unit maintenance activity to investigate suspected deficiencies.
The NDI/JOAP laboratory will set the standards and intervals of oil analysis.
A typical predictive maintenance technique is ferrography, which analyses iron in oil. | 0 | Theoretical and Fundamental Chemistry |
Repellents generally work by taking advantage of an animal's natural aversion to something, and often the thing chosen is something that the animal has learned to avoid (or instinctively avoids) in its natural environment.
Chemical repellents fall into two main categories, odor and taste. The former work better in the warm season and the latter, which ward off an animal only after it eats, in the cold season. (For example, the smell of the lawn fertilizer Milorganite is claimed to make it an effective repellent.) Such repellents mimic natural substances that deter animals and/or are designed to be so irritating to a specific animal or type of animal that it will avoid the protected object or area. Contact plant-origin repellents such as pepper, peppermint, tarragon, garlic, various essential oils, and castor oil, as well as diatomaceous earth and putrescent egg solids, are examples.
Further, some repellents function by inducing fear in the target animal. Such a repellent may contain animal urine, dried blood, or hair. Some animals will avoid anything that has the odor of the urine of their predators. Tiger urine is thus very effective at keeping away animals. Coyote urine has gained currency as a deer repellent. Fox urine is used to repel rabbits, groundhogs, woodchucks, squirrels and chipmunks. Bobcat urine repels moles, mice, voles and other rodents. Wolf urine is used to repel moose. Used cat litter is also effective. Domestic dogs can be repelled by vinegar.
Other repellents are not chemical. A simple electrified or barbed-wire fence can mechanically repel livestock or predator animals. Some electrical repellent systems have been tested against sharks. High-frequency whistles are used on vehicles to drive deer away from highways, and similar devices are used to deter certain types of insects or rodents. Repellents of this kind for domestic cats and dogs include ultrasonic devices which emit a high-frequency noise that does not affect humans. These types of non-chemical repellents are controversial, both because their effectiveness varies from animal to animal and because there have been few scientific studies conducted to prove that they work. They are, however, safe and humane, as are motion-activated sprinklers and electronic pet barriers, which latter are used by pet owners to confine their own pets to designated areas.
Flashing lights are used to repel lions in Kenya.
The ideal repellent is completely specific for the target animal; that is, it drives away the animal that one wishes to repel without affecting or harming any other animals or people. One type of animal repellent may be effective for raccoons, while another animal repellent may be more effective for skunks. It can be difficult to design a repellent method that drives away only undesirable animals while having no effect on people or other creatures. | 1 | Applied and Interdisciplinary Chemistry |
Further progress in studies of atomic structure was in tight connection with the advance to shorter wavelength in EUV region. Millikan, Sawyer, Bowen used electric discharges in vacuum to observe some emission spectral lines down to 13 nm they prescribed to stripped atoms. In 1927 Osgood and Hoag reported on grazing incidence concave grating spectrographs and photographed lines down to 4.4 nm (K of carbon). Dauvillier used a fatty acid crystal of large crystal grating space to extend soft x-ray spectra up to 12.1 nm, and the gap was closed. In the same period Manne Siegbahn constructed a very sophisticated grazing incidence spectrograph that enabled Ericson and Edlén to obtain spectra of vacuum spark with high quality and to reliably identify lines of multiply ionized atoms up to O VI, with five stripped electrons. Grotrian developed his graphic presentation of energy structure of the atoms. Russel and Saunders proposed their coupling scheme for the spin-orbit interaction and their generally recognized notation for spectral terms. | 0 | Theoretical and Fundamental Chemistry |
The first step in photosynthesis is the light-driven reduction (splitting) of water to provide the electrons for the photosynthetic electron transport chains as well as protons for the establishment of a proton gradient. The water-splitting reaction occurs on the lumenal side of the thylakoid membrane and is driven by the light energy captured by the photosystems. This oxidation of water conveniently produces the waste product O that is vital for cellular respiration. The molecular oxygen formed by the reaction is released into the atmosphere. | 0 | Theoretical and Fundamental Chemistry |
Asymmetric induction (also enantioinduction) describes the preferential formation in a chemical reaction of one enantiomer or diastereoisomer over the other as a result of the influence of a chiral feature present in the substrate, reagent, catalyst or environment. Asymmetric induction is a key element in asymmetric synthesis.
Asymmetric induction was introduced by Hermann Emil Fischer based on his work on carbohydrates. Several types of induction exist.
Internal asymmetric induction makes use of a chiral center bound to the reactive center through a covalent bond and remains so during the reaction. The starting material is often derived from chiral pool synthesis. In relayed asymmetric induction the chiral information is introduced in a separate step and removed again in a separate chemical reaction. Special synthons are called chiral auxiliaries. In external asymmetric induction chiral information is introduced in the transition state through a catalyst of chiral ligand. This method of asymmetric synthesis is economically most desirable. | 0 | Theoretical and Fundamental Chemistry |
In most cases the fractionation of polymers on a preparative scale is based on chromatographic methods (e.g. preparative SEC or Baker-Williams fractionation). Therefore, the production is normally limited to few grams only. For large scales of several grams up to kg or even tons the “continuous spin fractionation” can be used. F. Francuskiewicz gives an overview about preparative polymer fractionation. | 0 | Theoretical and Fundamental Chemistry |
FRET can be used to observe membrane fluidity, movement and dispersal of membrane proteins, membrane lipid-protein and protein-protein interactions, and successful mixing of different membranes. FRET is also used to study formation and properties of membrane domains and lipid rafts in cell membranes and to determine surface density in membranes. | 1 | Applied and Interdisciplinary Chemistry |
Zero-order ultrasensitivity was first described by Albert Goldbeter and Daniel Koshland, Jr in 1981 in a paper in the Proceedings of the National Academy of Sciences. They showed using mathematical modeling that modification of enzymes operating outside of first order kinetics required only small changes in the concentration of the effector to produce larger changes in the amount of modified protein. This amplification provided added sensitivity in biological control, and implicated the importance of this in many biological systems.
Many biological processes are binary (ON-OFF), such as cell fate decisions, metabolic states, and signaling pathways. Ultrasensitivity is a switch that helps decision-making in such biological processes. For example, in apoptotic process, a model showed that a positive feedback of inhibition of caspase 3 (Casp3) and Casp9 by inhibitors of apoptosis can bring about ultrasensitivity (bistability). This positive feedback cooperates with Casp3-mediated feedback cleavage of Casp9 to generate irreversibility in caspase activation (switch ON), which leads to cell apoptosis. Another model also showed similar but different positive feedback controls in Bcl-2 family proteins in apoptotic process.
Recently, Jeyeraman et al. have proposed that the phenomenon of ultrasensitivity may be further subdivided into three sub-regimes, separated by sharp stimulus threshold values: OFF, OFF-ON-OFF, and ON. Based on their model, they proposed that this sub-regime of ultrasensitivity, OFF-ON-OFF, is like a switch-like adaption which can be accomplished by coupling N phosphorylation–dephosphorylation cycles unidirectionally, without any explicit feedback loops.
Other recent work has emphasized that not only is the topology of networks important for creating ultrasensitivity responses, but that their composition (enzymes vs. transcription factors) strongly affects whether they will exhibit robust ultrasensitivity. Mathematical modeling suggests for a broad array of network topologies that a combination of enzymes and transcription factors tends to provide more robust ultrasensitivity than that seen in networks composed entirely of transcription factors or composed entirely of enzymes. | 1 | Applied and Interdisciplinary Chemistry |
An acoustic slowness surface can be determined for each pixel by propagating the acoustic wave in several directions. Having measured the SAW velocity in multiple directions the challenge is then to convert this information into the measurement of crystallographic orientation. The direct calculation of the orientation from velocity is a difficult problem. However, the numerical calculation of the SAW velocity as a function of SAW velocity is relatively simple, as first outlined by Farnell. Therefore, a database of possible slowness surfaces can be pre-calculated and compared to the measurement values. For each measurement pixel the orientation is given by the orientation of the pre-calculated velocity surface which best matches the measured data. These maps can spatially describe the crystal orientation of the material being interrogated and can be used to examine microtexture and sample morphology. The technique is applicable to any crystal structure, however transverse isotropy means the full orientation cannot be determined in hexagonal materials, such as titanium.
In order to calculate the predicted SAW velocity of the sample, the materials density and elastic constants must be known. Elastic constants are typically measured by ultrasonic techniques such as resonant ultrasound spectroscopy, with well-established values for most common engineering materials. However, it is possible to attempt the full inverse problem to determine both the elastic constants and crystallographic orientation from only the measured SAW velocity.
From orientation data, a wealth of information can be devised that aids in the understanding of the sample's microstructure and processing history. Recent developments include understanding: the prior texture of parent phases at elevated temperature; the storage and residual deformation after mechanical testing; the population of various microstructural features, including precipitates and grain boundary character. | 0 | Theoretical and Fundamental Chemistry |
In microbiology, methyl red is used in the methyl red test (MR test), used to identify bacteria producing stable acids by mechanisms of mixed acid fermentation of glucose (cf. Voges–Proskauer test).
The MR test, the "M" portion of the four IMViC tests, is used to identify enteric bacteria based on their pattern of glucose metabolism. All enterics initially produce pyruvic acid from glucose metabolism. Some enterics subsequently use the mixed acid pathway to metabolize pyruvic acid to other acids, such as lactic, acetic, and formic acids. These bacteria are called methyl-red positive and include Escherichia coli and Proteus vulgaris. Other enterics subsequently use the butylene glycol pathway to metabolize pyruvic acid to neutral end products. These bacteria are called methyl-red-negative and include Serratia marcescens and Enterobacter aerogenes. | 0 | Theoretical and Fundamental Chemistry |
Influenza A is involved in most strains of the flu. It is an enveloped RNA virus. It has a protein membrane containing the glycoproteins hemagglutinin (HA) and neuraminidase (NA) which are used by the virus to enter a host cell and to release itself and its copies from the host cell. Each strain of the influenza virus has a different pattern of glycoproteins; the glycoproteins themselves have variability as well. | 1 | Applied and Interdisciplinary Chemistry |
The production of bottromycin by S. bottropensis and S. scabies, as well as the production of a bottromycin analog termed bottromycin D, has been studied. It was independently confirmed in 2012 by multiple groups that bottromycin is produced as a ribosomal peptide natural product that it subsequently post-translationally modified. Before this, it was unclear whether bottromycin was produced by nonribosomal peptide synthetase machinery (NRPS). The presence of amino acids other than the 20 proteinogenic amino acids is often a feature of NRPS products because NRPS machinery can directly incorporate other amino acids, among other chemical building blocks. Ribosomal peptide synthesis, which is the same machinery that produces all proteins found in the cell, is limited to the 20 proteinogenic amino acids. However, bottromycin was found to be a highly modified ribosomal peptide by a combination of genome mining and gene deletion studies.
In ribosomal peptide synthesis, the final product results from modifications to a linear peptide starting material translated by the ribosome from an mRNA transcript. In S. scabies the precursor peptide, termed BtmD, is a 44-amino acid peptide. The precursor peptide is termed BmbC in S. bottropensis. The amino acids forming the bottromycin core are residues 2-9 in BtmD: Gly-Pro-Val-Val-Val-Phe-Asp-Cys. In bottromycin D, the sequence is Gly-Pro-Ala-Val-Val-Phe-Asp-Cys, and the precursor peptide is termed BstA. BstA shares high sequence homology with BtmD in the follower peptide region. Unlike other ribosomal peptide natural products, which are normally synthesized with a leader peptide that is cleaved, bottromycin is synthesized with a follower peptide. The presence of a follower peptide was identified by bioinformatic analysis of the bottromycin biosynthetic cluster.
The complete biosynthetic gene cluster for bottromycin has been identified. It is predicted to contain 13 genes, including the precursor peptide (notation will follow Crone and colleagues; other studies had similar results). One of the genes in the cluster, btmL, is proposed to be a transcriptional regulator. Another gene, btmA, is proposed to export bottromycin. The remaining ten genes are expected to modify the precursor peptide btmD from a linear peptide to the final macrocyclic product.
A biosynthetic pathway has been hypothesized based on proposed gene functions (see figure). btmM, with homology to Zn+2 aminopeptidases, is predicted to cleave the N-terminal methionine residue, which is not present in the bottromycin final product. btmE and btmF both contain YcaO-like domains. It is believed that one Although it is unclear which enzyme is responsible for which step, it is hypothesized that one catalyzes macrocyclic amidine formation while the other catalyzes thiazoline formation. btmJ, encoding an enzyme with cytochrome P450 homology, may oxidize the thiazoline to the thiazole. btmH or btmI both have homology to hydrolytic enzymes (α/β hydrolase and metallo-dependent hydrolase, respectively) may catalyze follower peptide hydrolysis. An alternative proposed role for btmH or btmI is to function as a cyclodehydratase in macrocyclization. Gene deletion studies failed to elucidate the function of other proteins within the cluster. | 0 | Theoretical and Fundamental Chemistry |
In the presence of a non-competitive inhibitor, the apparent enzyme affinity is equivalent to the actual affinity. In terms of Michaelis-Menten kinetics, K = K. This can be seen as a consequence of Le Chatelier's principle because the inhibitor binds to both the enzyme and the enzyme-substrate complex equally so that the equilibrium is maintained. However, since some enzyme is always inhibited from converting the substrate to product, the effective enzyme concentration is lowered.
Mathematically, | 1 | Applied and Interdisciplinary Chemistry |
In 1956, C. Gordon Zubrod, who had formerly led the development of antimalarial agents for the United States Army, took over the Division of Cancer Treatment of the NCI and guided development of new drugs. In the two decades that followed the establishment of the NCCSC, a large network of cooperative clinical trial groups evolved under the auspices of the NCI to test anticancer agents. Zubrod had a particular interest in natural products, and established a broad programme for collecting and testing plant and marine sources, a controversial programme that led to the discovery of taxanes (in 1964) and camptothecins (in 1966). Both classes of drug were isolated and characterized by the laboratory of Monroe Wall at the Research Triangle Institute. | 1 | Applied and Interdisciplinary Chemistry |
Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation. It can be given on a volumetric or mass (gravimetric) basis. | 0 | Theoretical and Fundamental Chemistry |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.