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Materials can transmit (e.g. glass) or reflect (e.g. metals) visible light.
Many materials will transmit some wavelengths while blocking others. For example, window glass is transparent to visible light, but much less so to most of the frequencies of ultraviolet light that cause sunburn. This property is used for frequency-selective optical filters, which can alter the color of incident light.
For some purposes, both the optical and mechanical properties of a material can be of interest. For example, the sensors on an infrared homing ("heat-seeking") missile must be protected by a cover that is transparent to infrared radiation. The current material of choice for high-speed infrared-guided missile domes is single-crystal sapphire. The optical transmission of sapphire does not actually extend to cover the entire mid-infrared range (3–5 µm), but starts to drop off at wavelengths greater than approximately 4.5 µm at room temperature. While the strength of sapphire is better than that of other available mid-range infrared dome materials at room temperature, it weakens above 600 °C. A long-standing trade-off exists between optical bandpass and mechanical durability; new materials such as transparent ceramics or optical nanocomposites may provide improved performance.
Guided lightwave transmission involves the field of fiber optics and the ability of certain glasses to transmit, simultaneously and with low loss of intensity, a range of frequencies (multi-mode optical waveguides) with little interference between them. Optical waveguides are used as components in integrated optical circuits or as the transmission medium in optical communication systems. | 0 | Theoretical and Fundamental Chemistry |
Davys laboratory assistant, Michael Faraday, went on to enhance Davys work and would become the more famous and influential scientist. Davy is supposed to have even claimed Faraday as his greatest discovery. Davy later accused Faraday of plagiarism, however, causing Faraday (the first Fullerian Professor of Chemistry) to cease all research in electromagnetism until his mentor's death.
According to one of Davy's biographers, June Z. Fullmer, he was a deist.
Of a sanguine, somewhat irritable temperament, Davy displayed characteristic enthusiasm and energy in all his pursuits. As is shown by his verses and sometimes by his prose, his mind was highly imaginative; the poet Coleridge declared that if he "had not been the first chemist, he would have been the first poet of his age", and Southey said that "he had all the elements of a poet; he only wanted the art." In spite of his ungainly exterior and peculiar manner, his happy gifts of exposition and illustration won him extraordinary popularity as a lecturer, his experiments were ingenious and rapidly performed, and Coleridge went to hear him "to increase his stock of metaphors." The dominating ambition of his life was to achieve fame; occasional petty jealousy did not diminish his concern for the "cause of humanity", to use a phrase often employed by him in connection with his invention of the miners' lamp. Careless about etiquette, his frankness sometimes exposed him to annoyances he might have avoided by the exercise of tact. | 1 | Applied and Interdisciplinary Chemistry |
Asthma is characterized by eosinophil-induced inflammation motivated by a type 2 helper T cell (Th2). By targeting the transcription factor, GATA3, of the Th2 pathway, with DNAzyme it may be possible to negate the inflammation. The safety and efficacy of SB010, a novel 10-23 DNAzyme was evaluated, and found to have the ability to cleave and inactivate GATA3 messenger RNA in phase IIa clinical trials. Treatment with SB010 significantly offset both late and early asthmatic responses after allergen aggravation in male patients with allergic asthma.
The transcription factor GATA-3 is also an interesting target, of the DNAzyme topical formulation SB012, for a novel therapeutic strategy in ulcerative colitis (UC). UC is an idiopathic inflammatory bowel diseases defined by chronically relapsing inflammations of the gastrointestinal tract, and characterized by a superficial, continuous mucosal inflammation, which predominantly affects the large intestine. Patients that do not effectively respond to current UC treatment strategies exhibit serious drawbacks one of which may lead to colorectal surgery, and can result in a severely compromised quality of life. Thus, patients with moderate or severe UC may significantly benefit from these new therapeutic alternatives, of which SB012 is in phase I clinical trials.
Atopic dermatitis (AD) is a chronic inflammatory skin disorder, in which patients suffer from eczema, often severe pruritus on the affected skin, as well as complications and secondary infections. AD surfaces from an upregulation of Th2-modified immune responses, therefore a novel AD approach using DNAzymes targeting GATA-3 is a plausible treatment option. The topical DNAzyme SB011 is currently in phase II clinical trials.
DNAzyme research for the treatment of cancer is also underway. The development of a 10-23 DNAzyme that can block the expression of IGF-I (Insulin-like growth factor I, a contributor to normal cell growth as well as tumorigenesis) by targeting its mRNA could be useful for blocking the secretion of IGF-I from prostate storm primary cells ultimately inhibiting prostate tumor development. Additionally, with this treatment it is expected that hepatic metastasis would also be inhibited, via the inhibition of IGF-I in the liver (the major source of serum IGF-I). | 0 | Theoretical and Fundamental Chemistry |
Many explanations fall into this category. First, the secondary orbital interactions theory emphasized that electron-donating heteroatom in the α-position could contribute to increased orbital interaction with the substrate, which stabilizes the transition state (TS) and gives greater reactivity. Second, the electron transfer (ET) mechanism presents that the heteroatom in the α position could stabilize the S2 transition state which has a single electron transfer (free radical) character. Other driving forces including the tighter transition state and higher polarizability of α-nucleophiles, involvement of intramolecular catalysis also plays a role. Another in silico study did find a correlation between the alpha effect and the so-called deformation energy, which is the electronic energy required to bring the two reactants together in the transition state. | 0 | Theoretical and Fundamental Chemistry |
Two main modes of release exist, the fission products can be vaporised or small particles of the fuel can be dispersed. | 0 | Theoretical and Fundamental Chemistry |
Ionic Atmosphere is a concept employed in Debye–Hückel theory which explains the electrolytic conductivity behaviour of solutions. It can be generally defined as the area at which a charged entity is capable of attracting an entity of the opposite charge. | 0 | Theoretical and Fundamental Chemistry |
Once through the observation cell the mixture enters a third syringe that contains a piston that is driven by the flow to activate a switch to stop the flow and activate the observation. | 0 | Theoretical and Fundamental Chemistry |
Norvaline and norleucine (one hydrocarbon group longer) both possess the nor- prefix for historical reason, despite current conventional usage of the prefix to denote a missing hydrocarbon group (under which they would theoretically be called "dihomoalanine" and "trihomoalanine"). The name is not systematic, and the IUPAC/IUB Joint Commission on Nomenclature recommends that this name should be abandoned and the systematic name should be used. | 1 | Applied and Interdisciplinary Chemistry |
Primary energy sources are transformed in energy conversion processes to more convenient forms of energy that can directly be used by society, such as electrical energy, refined fuels, or synthetic fuels such as hydrogen fuel. In the field of energetics, these forms are called energy carriers and correspond to the concept of "secondary energy" in energy statistics. | 0 | Theoretical and Fundamental Chemistry |
The ISBC's Lavoisier Medal is awarded to an internationally acknowledged scientist for an outstanding contribution to the development and/or the application of direct calorimetry in biology and medicine
Source: [http://www.biocalorimetry.org/2013/09/30/the-lavoisier-medal/ ISBC]
:*1990: Ingemar Wadsö, Lund, Sweden
:*1992: Richard B. Kemp, Aberystwyth, UK
:*1994: [http://www.chem.byu.edu/Site/EmeritusFaculty/LeeDHansen(template) Lee Hansen], Provo, USA
:*1997: Ingolf Lamprecht, Berlin, Germany
:*1999: Anthony E. Beezer, London, UK
:*2001: Lena Gustafsson, Göteborg, Sweden
:*2003: Erich Gnaiger, Innsbruck, Austria
:*2006: Mario Monti, Lund, Sweden
:*2010: Edwin Battley, Stony Brook NY, USA
:*2014: Urs von Stockar, Lausanne, Switzerland | 1 | Applied and Interdisciplinary Chemistry |
Sialic acid is synthesized by glucosamine 6 phosphate and acetyl-CoA through a transferase, resulting in N-acetylglucosamine-6-P. This becomes N-acetylmannosamine-6-P through epimerization, which reacts with phosphoenolpyruvate producing N-acetylneuraminic-9-P (sialic acid). For it to become active to enter in the oligosaccharide biosynthesis process of the cell, a monophosphate nucleoside is added, which comes from a cytidine triphosphate, turning sialic acid into cytidine monophosphate-sialic acid (CMP-sialic acid). This compound is synthesized in the nucleus of the animal cell.
In bacterial systems, sialic acids can be also biosynthesized by an aldolase. This enzyme uses for example a mannose derivative as a substrate, inserting three carbons from pyruvate into the resulting sialic acid structure. These enzymes can be used for chemoenzymatic synthesis of sialic acid derivatives. | 0 | Theoretical and Fundamental Chemistry |
The Queensland Acid Sulfate Soil Technical Manual: Soil Management Guidelines is highly recommended for both scientists and engineers due to its excellent discussion on risk assessment and management strategies. Management strategies discussed in the manual include: avoidance, minimisation of disturbance, neutralisation, hydraulic separation, strategic reburial / interment, and stockpiling.
The Queensland government Acid Sulfate Soils: Laboratory Methods Guidelines is recommended for a discussion on the analytical techniques. Although the National guidance constitutes the primary authority on the subject, and covers a broader range of issues, this manual provides more commentary on the analytical techniques such as SPOCAS. | 0 | Theoretical and Fundamental Chemistry |
Crystal violet is used as a textile and paper dye, and is a component of navy blue and black inks for printing, ball-point pens, and inkjet printers. It is sometimes used to colourize diverse products such as fertilizer, antifreeze, detergent, and leather.
The dye is used as a histological stain, particularly in Gram staining for classifying bacteria.
When conducting DNA gel electrophoresis, crystal violet can be used as a nontoxic DNA stain as an alternative to fluorescent, intercalating dyes such as ethidium bromide. Used in this manner, it may be either incorporated into the agarose gel or applied after the electrophoresis process is finished. Used at a 0.001% concentration and allowed to stain a gel after electrophoresis for 30 minutes, it can detect as little as 16 ng of DNA. Through use of a methyl orange counterstain and a more complex staining method, sensitivity can be improved further to 8 ng of DNA. When crystal violet is used as an alternative to fluorescent stains, it is not necessary to use ultraviolet illumination; this has made crystal violet popular as a means of avoiding UV-induced DNA destruction when performing DNA cloning in vitro.
In biomedical research, crystal violet can be used to stain the nuclei of adherent cells. In this application, crystal violet works as an intercalating dye and allows the quantification of DNA which is proportional to the number of cells.
In forensics, crystal violet was used to develop fingerprints. Crystal violet is also used as a tissue stain in the preparation of light microscopy sections. In laboratory, solutions containing crystal violet and formalin are often used to simultaneously fix and stain cells grown in tissue culture to preserve them and make them easily visible, since most cells are colourless. It is also sometimes used as a cheap way to put identification markings on laboratory mice; since many strains of lab mice are albino, the purple colour stays on their fur for several weeks.
In body piercing, gentian violet is commonly used to mark the location for placing piercings, including surface piercings.
Marking blue, used to mark out pieces in metalworking, is composed of methylated spirits, shellac, and gentian violet. | 0 | Theoretical and Fundamental Chemistry |
After Iraqi chemical attacks against Iranian soldiers and civilians, from 1983 to 1988, the number of people sustained injuries, including respiratory (42%), ocular (39%) and skin complications (25%) was more than 3,400 – a number which increased to at least 45,000 twenty years later, "due to the occurrence of late respiratory complications of mustard gas exposure." "The latency period can be as much as 40 years" and "So almost every day there are new cases — 30 years after the war," said Shahriar Khateri, the co-founder of the Society for Chemical Weapons Victims Support. According to Farhad Hashemnezhad in 2002, at least 20 percent of the patients were "civilians who didnt think they were close enough to be exposed." This large number of chemically affected veterans has made Iran the worlds largest laboratory for the study of the effects of chemical weapons. According to a declassified CIA report, as a result of Iraqs repeated use of nerve agents and toxic gases in the 1980s, Iran suffered more than 50,000 casualties mostly by mustard gas used in dusty, liquid and vapor forms packed into bombs and artillery shells which were then fired at the front lines and beyond, at targets such as hospitals. The number of registered chemically affected veterans was 70,000 by 2014, according to Shahriar Khateri, Irans leading expert on chemical weapons victims. "awareness could have saved lives," Khateri said. Doctors estimate that the final toll of Iraq's chemical weapons could be as high as 90,000, equal to the total deaths from all toxic gases in World War I.
During the Iran–Iraq War, mustard gas was used by Iraq against Iran, and it was the "first time ever that nerve agents such as sarin and tabun were employed." Experiencing the outcomes of the chemical weapons, chemical warfare veterans believe that the younger generations should be instructed that "war is not a computer game." "We want to show how painful the consequences are. We dont want revenge. We just want to show what happens so it wont happen again," said Saadi, injured by Iraqi mustard gas. | 1 | Applied and Interdisciplinary Chemistry |
An intermediate energy projectile transfers energy or picks up or loses nucleons to the nucleus in a single quick (10 second) event. Energy and momentum transfer are relatively small. These are particularly useful in experimental nuclear physics, because the reaction mechanisms are often simple enough to calculate with sufficient accuracy to probe the structure of the target nucleus. | 0 | Theoretical and Fundamental Chemistry |
* The recA1 mutation is a single point mutation that replaces glycine 160 of the recA polypeptide with an aspartic acid residue in order to disable the activity of the recombinases and inactivate homologous recombination.
* The endA1 mutation inactivates an intracellular endonuclease to prevent it from degrading the inserted plasmid. | 1 | Applied and Interdisciplinary Chemistry |
The symbiotic relationship between the Hawaiian bobtail squid Euprymna scolopes and the marine gram-negative bacterium Aliivibrio fischeri has been well studied. The two organisms exhibit a mutualistic relationship in which bioluminescence produced by A. fischeri helps to attract pray to the squid host, which provides nutrient-rich tissues and a protected environment forA. fischeri. Bioluminescence provided by A. fischeri also aids in the defense of the squid E. scolopes by providing camouflage during its nighttime foraging activity. Following bacterial colonization, the specialized organs of the squid undergo developmental changes and a relationship becomes established. The squid expels 90% of the bacterial population each morning, because it no longer needs to produce bioluminescence in the daylight. This expulsion benefits the bacteria by aiding in their dissemination. A single expulsion by one bobtail squid produces enough bacterial symbionts to fill 10,000m of seawater at a concentration that is comparable to what is found in coastal waters. Thus, in at least some habitats, the symbiotic relationship between A. fischeri and E. scolopes plays a key role in determining the abundance and distribution of E. scolopes. There is a higher abundance of A. fischeri in the vicinity of a population of E. scolopes and this abundance markedly decreases with increasing distance from the host's habitat.
Bioluminescent Photobacterium species also engage in mutually beneficial associations with fish and squid. Dense populations of P. kishitanii, P. leiogathi, and P. mandapamensis can live in the light organs of marine fish and squid, and are provided with nutrients and oxygen for reproduction in return for providing bioluminescence to their hosts, which can aid in sex-specific signaling, predator avoidance, locating or attracting prey, and schooling.<!-- Empty reference | 1 | Applied and Interdisciplinary Chemistry |
Chemical handles are used to detect post-translationally modified proteins. Recently, there is a N6pATP that contains an alkynyl tag (propargyl) at the N6 position of the adenine of ATP. This N6pATP combines with the click reaction to detect AMPylated proteins. To detect unrecognized modified protein and label VopS substrates, ATP derivatives with a fluorophore at the adenine N6 NH2 is utilized to do that. | 1 | Applied and Interdisciplinary Chemistry |
The film can be used as a sensor. As the film is charged, it creates an electric field. When pressure is applied to the film, the film's thickness is reduced and changes in the shapes of the individual voids in its structure occur. Any electric charges residing in these voids will move and create mirror charges at the electrode surfaces of the film. These charges are proportional to the force applied to the film, which is given by the equation:
where ΔF is the dynamic force, Δq is the charge generated, and k is the sensitivity factor. | 1 | Applied and Interdisciplinary Chemistry |
There are currently around 19 research groups at the institute. The research at MPI-Marburg broadly focuses on understanding the functioning of microorganisms at the molecular, cellular and community levels. In particular, the focus is the mechanisms of cellular and community adaptation of bacteria in response to changes in the environment. | 0 | Theoretical and Fundamental Chemistry |
The relationship below provides a way to determine the volume-based concentration of any individual gaseous component
where c is the concentration of component i.
Dalton's law is not strictly followed by real gases, with the deviation increasing with pressure. Under such conditions the volume occupied by the molecules becomes significant compared to the free space between them. In particular, the short average distances between molecules increases intermolecular forces between gas molecules enough to substantially change the pressure exerted by them, an effect not included in the ideal gas model. | 0 | Theoretical and Fundamental Chemistry |
The G-less assay can be performed on a circular plasmid to measure levels of transcription. A circular plasmid provides a more efficient template in many systems when compared to other assays such as runoff transcription, in which a cleaved end is required. This method generates radiolabeled transcripts very efficiently because it bypasses the unnecessary process of performing other indirect mRNA product measurements. The promoter is inserted into a circular plasmid containing the G-less cassette, which will generate a transcript of a certain length that omits random and nonspecific transcription throughout the plasmid. Most crude systems, such as HeLa nuclear extracts, are used because they contain low amounts of contaminating GTP that lead to background transcription and may occasionally cause random transcription to read through the G-less cassette. | 1 | Applied and Interdisciplinary Chemistry |
A diureide is a complex nitrogenous substance regarded as containing two molecules of urea or their radicals, e.g. uric acid or allantoin. | 0 | Theoretical and Fundamental Chemistry |
Cells use glucose for energy. This normally occurs by phosphorylation from the enzyme hexokinase. However, if large amounts of glucose are present (as in diabetes mellitus), hexokinase becomes saturated and the excess glucose enters the polyol pathway when aldose reductase reduces it to sorbitol. This reaction oxidizes NADPH to NADP+. Sorbitol dehydrogenase can then oxidize sorbitol to fructose, which produces NADH from NAD+. Hexokinase can return the molecule to the glycolysis pathway by phosphorylating fructose to form fructose-6-phosphate. However, in uncontrolled diabetics that have high blood glucose - more than the glycolysis pathway can handle - the reactions mass balance ultimately favors the production of sorbitol.
Activation of the polyol pathway results in a decrease of reduced NADPH and oxidized NAD+; these are necessary co-factors in redox reactions throughout the body, and under normal conditions they are not interchangeable. The decreased concentration of these NADPH leads to decreased synthesis of reduced glutathione, nitric oxide, myo-inositol, and taurine. Myo-inositol is particularly required for the normal function of nerves. Sorbitol may also glycate nitrogens on proteins, such as collagen, and the products of these glycations are referred-to as AGEs - advanced glycation end-products. AGEs are thought to cause disease in the human body, one effect of which is mediated by RAGE (receptor for advanced glycation end-products) and the ensuing inflammatory responses induced. They are seen in the hemoglobin A1C tests performed on known diabetics to assess their levels of glucose control. | 1 | Applied and Interdisciplinary Chemistry |
The R symbol was introduced by 19th-century French chemist Charles Frédéric Gerhardt, who advocated its adoption on the grounds that it would be widely recognizable and intelligible given its correspondence in multiple European languages to the initial letter of "root" or "residue": French ("root") and ("residue"), these terms respective English translations along with radical (itself derived from Latin below), Latin ("root") and ("residue"), and German ' ("remnant" and, in the context of chemistry, both "residue" and "radical"). | 0 | Theoretical and Fundamental Chemistry |
In a mixture of gases, the fugacity of each component has a similar definition, with partial molar quantities instead of molar quantities (e.g., instead of and instead of ):
and
where is the partial pressure of component . The partial pressures obey Dalton's law:
where is the total pressure and is the mole fraction of the component (so the partial pressures add up to the total pressure). The fugacities commonly obey a similar law called the Lewis and Randall rule:
where is the fugacity that component would have if the entire gas had that composition at the same temperature and pressure. Both laws are expressions of an assumption that the gases behave independently. | 0 | Theoretical and Fundamental Chemistry |
* [https://books.google.com.ua/books/about/Le_fer_de_Dieu.html?id=urRyoAEACAAJ&redir_esc=y Le fer de Dieu : histoire de la météorite de Chinguetti], with Théodore Monod, Actes Sud, 2008, 152 pages. ISBN 978-2742775521.
* [https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL047173 Low temperature magnetic transition of chromite in ordinary chondrites], J. Gattacceca et al., 2011. | 0 | Theoretical and Fundamental Chemistry |
* 1999 Marie Curie Fellowship, University of Cambridge, United Kingdom.
* 2000 Junior Research Fellowship, Wolfson College, Cambridge, United Kingdom.
* 2001 Royal Society University Research Fellowship, University of Cambridge, United Kingdom.
* 2011 ERC Starting Grant (subsidy) from the European Research Council for research into: Self-replication in dynamic molecular networks
* 2013 Vici grant from the Dutch Research Council (NWO) for research into: the Darwinian evolution of molecules. (Vici grants are intended for excellent senior researchers who can demonstrably develop their own innovative research lines and who are suitable for coaching early-career researchers.
* 2013 Appointed as Fellow of the Royal Society of Chemistry.
* 2013 Visiting professor, University of Strasbourg, France.
* 2017 ERC Advanced Grant (subsidy) from the European Research Council.
* 2018 Visiting professor, Ludwig Maximilian University of Munich, Germany.
* 2018 Supramolecular chemistry prize of the Royal Society of Chemistry.
* 2020 Member of the Royal Dutch Academy of Science ([https://knaw.nl/en/news/news/royal-academy-selects-eighteen-new-members link]).
* 2023 ERC Synergy Grant (subsidy) from the European Research Council. | 0 | Theoretical and Fundamental Chemistry |
Euxinia most frequently occurred in the Earth's ancient oceans, but its distribution and frequency of occurrence are still under debate. The original model was that it was quite constant for approximately a billion years. Some meta-analyses have questioned how persistent euxinic conditions were based on relatively small black shale deposits in a period when the ocean should have theoretically been preserving more organic matter.
Before the Great Oxygenation Event happened approximately 2.3 billion years ago, there was little free oxygen in either the atmosphere or the ocean. It was originally thought that the ocean accumulated oxygen soon after the atmosphere did, but this idea was challenged by Canfield in 1998 when he proposed that instead of the deep ocean becoming oxidizing, it became sulfidic. This hypothesis is partially based on the disappearance of banded iron formations from the geological records 1.8 billion years ago. Canfield argued that although enough oxygen entered the atmosphere to erode sulfides in continental rocks, there was not enough oxygen to mix into the deep ocean. This would result in an anoxic deep ocean with an increased flux of sulfur from the continents. The sulfur would strip iron ions from the sea water, resulting in iron sulfide (pyrite), a portion of which was eventually buried. When sulfide became the major oceanic reductant instead of iron, the deep water became euxinic. This has become what is known as the Canfield ocean, a model backed by the increase in presence of δS in sedimentary pyrite and the discovery of evidence of the first sulfate evaporites.
Anoxia and sulfidic conditions often occur together. In anoxic conditions anaerobic, sulfate reducing bacteria convert sulfate into sulfide, creating sulfidic conditions. The emergence of this metabolic pathway was very important in the pre-oxygenated oceans because adaptations to otherwise inhabitable or "toxic" environments like this may have played a role in the diversification of early eukaryotes and protozoa in the pre-Phanerozoic.
Euxinia still occurs occasionally today, mostly in meromictic lakes and silled basins such as the Black Sea and some fjords. It is rare in modern times; less than 0.5% of today's sea floor is euxinic. | 0 | Theoretical and Fundamental Chemistry |
Nanowell array formats are used to express individual proteins in small volume reaction vessels or nanowells (Figure 4). This format is sometimes preferred because it avoids the need to immobilize the target protein which might result in the potential loss of protein activity. The miniaturization of the array also conserves solution and precious compounds that might be used in screening assays. Moreover, the structural properties of individual wells help to prevent cross-contamination among chambers. In 2012 an improved NAPPA was published, which used a nanowell array to prevent diffusion. Here the DNA was immobilized in the well together with an anti-GST antibody. Then cell-free expression mix was added and the wells closed by a lid. The nascent proteins containing a GST-tag were bound to the well surface enabling a NAPPA-array with higher density and nearly no cross-contaminations. | 1 | Applied and Interdisciplinary Chemistry |
A well-studied class of solid-state compounds related to the chalcohalides are molybdenum clusters of the type AMoX with X sulfur or selenium and A an interstitial atom such as Pb. These materials, called Chevrel phases or Chevrel clusters, have been actively studied because they are type II superconductors with relatively high critical fields. Such materials are prepared by high temperature (1100 °C) reactions of the chalcogen and Mo metal. Structurally related, soluble analogues have been prepared, e.g., MoS(PEt). | 0 | Theoretical and Fundamental Chemistry |
There are two major applications to studying the genome at the single cell level. One application is to track the changes that occur in bacterial populations, where phenotypic differences are often seen. These differences are missed by bulk sequencing of a population, but can be observed in single cell sequencing. The second major application is to study the genetic evolution of cancer. Since cancer cells are constantly mutating it is of great interest to see how cancers evolve at the genetic level. These patterns of somatic mutations and copy number aberration can be observed using single cell sequencing. | 1 | Applied and Interdisciplinary Chemistry |
Transcription can be repressed in a variety of ways, and therefore can be derepressed in different ways as well. A common mechanism is allosteric regulation. This is when a substrate binds a repressor protein and causes it to undergo a conformational change. If the repressor is bound upstream of a gene, such as in an operator sequence, then it would be repressing the gene's expression. This conformational change would take away the repressor’s ability to bind DNA, thus removing its repressive effect on transcription.
Another form of transcriptional derepression uses chromatin remodeling complexes. For transcription to occur, RNA polymerase needs to have access to the promoter sequence of the gene or it cannot bind the DNA. Sometimes these sequences are wrapped around nucleosomes or are in condensed heterochromatin regions, and are therefore inaccessible. Through different chromatin remodeling mechanisms these promoter sequences can become accessible to the RNA polymerase, and transcription becomes derepressed.
Transcriptional derepression may also occur at the level of transcription factor activation. Certain families of transcription factors are non-functional on their own because their active domains are blocked by another part of the protein. Substrate binding to this second, regulatory domain causes a conformational change in the protein to allows access to the active domain. This lets the transcription factor bind to DNA and serve its function, thus derepressing the transcription factor. | 1 | Applied and Interdisciplinary Chemistry |
Hypertension is a risk factor for atherosclerosis, heart failure, coronary artery disease, stroke, renal disease, and peripheral arterial disease, and is the most important risk factor for cardiovascular morbidity and mortality, in industrialized countries. Prior to 1940 approximately 23% of all deaths among persons over age 50 were attributed to hypertension. Severe cases of hypertension were treated by surgery.
Early developments in the field of treating hypertension included quaternary ammonium ion sympathetic nervous system blocking agents, but these compounds were never widely used due to their severe side effects, because the long-term health consequences of high blood pressure had not yet been established, and because they had to be administered by injection.
In 1952 researchers at Ciba discovered the first orally available vasodilator, hydralazine. A major shortcoming of hydralazine monotherapy was that it lost its effectiveness over time (tachyphylaxis). In the mid-1950s Karl H. Beyer, James M. Sprague, John E. Baer, and Frederick C. Novello of Merck and Co. discovered and developed chlorothiazide, which remains the most widely used antihypertensive drug today. This development was associated with a substantial decline in the mortality rate among people with hypertension. The inventors were recognized by a Public Health Lasker Award in 1975 for "the saving of untold thousands of lives and the alleviation of the suffering of millions of victims of hypertension".
A 2009 Cochrane review concluded that thiazide antihypertensive drugs reduce the risk of death (RR 0.89), stroke (RR 0.63), coronary heart disease (RR 0.84), and cardiovascular events (RR 0.70) in people with high blood pressure. In the ensuring years other classes of antihypertensive drug were developed and found wide acceptance in combination therapy, including loop diuretics (Lasix/furosemide, Hoechst Pharmaceuticals, 1963), beta blockers (ICI Pharmaceuticals, 1964) ACE inhibitors, and angiotensin receptor blockers. ACE inhibitors reduce the risk of new onset kidney disease [RR 0.71] and death [RR 0.84] in diabetic patients, irrespective of whether they have hypertension. | 1 | Applied and Interdisciplinary Chemistry |
The most recently completed dexpramipexole clinical trial was EXHALE-1 (AS201), a Phase II clinical trial in participants with moderate-to-severe eosinophilic asthma. Dexpramipexole demonstrated highly significant, dose dependent eosinophil lowering during the primary assessment phase and was maximal at Week 12. Dexpramipexole produced clinically relevant changes in FEV across study arms and time points and the magnitude of FEV improvement was comparable to currently approved biologics. Dexpramipexole was well tolerated in the trial, with adverse events balanced across treatment and placebo groups, no serious adverse events, and no adverse events leading to discontinuation. | 0 | Theoretical and Fundamental Chemistry |
The air in a room can be supplied and removed in several ways, for example via ceiling ventilation, cross ventilation, floor ventilation or displacement ventilation.
Furthermore, the air can be circulated in the room using vortexes which can be initiated in various ways: | 1 | Applied and Interdisciplinary Chemistry |
Elements are composed either of one nuclide (mononuclidic elements), or of more than one naturally occurring isotopes. The unstable (radioactive) isotopes are either primordial or postprimordial. Primordial isotopes were a product of stellar nucleosynthesis or another type of nucleosynthesis such as cosmic ray spallation, and have persisted down to the present because their rate of decay is so slow (e.g. uranium-238 and potassium-40). Post-primordial isotopes were created by cosmic ray bombardment as cosmogenic nuclides (e.g., tritium, carbon-14), or by the decay of a radioactive primordial isotope to a radioactive radiogenic nuclide daughter (e.g. uranium to radium). A few isotopes are naturally synthesized as nucleogenic nuclides, by some other natural nuclear reaction, such as when neutrons from natural nuclear fission are absorbed by another atom.
As discussed above, only 80 elements have any stable isotopes, and 26 of these have only one stable isotope. Thus, about two-thirds of stable elements occur naturally on Earth in multiple stable isotopes, with the largest number of stable isotopes for an element being ten, for tin (). There are about 94 elements found naturally on Earth (up to plutonium inclusive), though some are detected only in very tiny amounts, such as plutonium-244. Scientists estimate that the elements that occur naturally on Earth (some only as radioisotopes) occur as 339 isotopes (nuclides) in total. Only 251 of these naturally occurring nuclides are stable, in the sense of never having been observed to decay as of the present time. An additional 35 primordial nuclides (to a total of 286 primordial nuclides), are radioactive with known half-lives, but have half-lives longer than 100 million years, allowing them to exist from the beginning of the Solar System. See list of nuclides for details.
All the known stable nuclides occur naturally on Earth; the other naturally occurring nuclides are radioactive but occur on Earth due to their relatively long half-lives, or else due to other means of ongoing natural production. These include the afore-mentioned cosmogenic nuclides, the nucleogenic nuclides, and any radiogenic nuclides formed by ongoing decay of a primordial radioactive nuclide, such as radon and radium from uranium.
An additional ~3000 radioactive nuclides not found in nature have been created in nuclear reactors and in particle accelerators. Many short-lived nuclides not found naturally on Earth have also been observed by spectroscopic analysis, being naturally created in stars or supernovae. An example is aluminium-26, which is not naturally found on Earth but is found in abundance on an astronomical scale.
The tabulated atomic masses of elements are averages that account for the presence of multiple isotopes with different masses. Before the discovery of isotopes, empirically determined noninteger values of atomic mass confounded scientists. For example, a sample of chlorine contains 75.8% chlorine-35 and 24.2% chlorine-37, giving an average atomic mass of 35.5 atomic mass units.
According to generally accepted cosmology theory, only isotopes of hydrogen and helium, traces of some isotopes of lithium and beryllium, and perhaps some boron, were created at the Big Bang, while all other nuclides were synthesized later, in stars and supernovae, and in interactions between energetic particles such as cosmic rays, and previously produced nuclides. (See nucleosynthesis for details of the various processes thought responsible for isotope production.) The respective abundances of isotopes on Earth result from the quantities formed by these processes, their spread through the galaxy, and the rates of decay for isotopes that are unstable. After the initial coalescence of the Solar System, isotopes were redistributed according to mass, and the isotopic composition of elements varies slightly from planet to planet. This sometimes makes it possible to trace the origin of meteorites. | 0 | Theoretical and Fundamental Chemistry |
The basis for the ISFET is the MOSFET. Dutch engineer Piet Bergveld, at the University of Twente studied the MOSFET and realized it could be adapted into a sensor for electrochemical and biological applications. This led to Bergveld's invention of the ISFET in 1970. He described the ISFET as "a special type of MOSFET with a gate at a certain distance". It was the earliest Biosensor FET (BioFET).
ISFET sensors could be implemented in integrated circuits based on CMOS (complementary MOS) technology. ISFET devices are widely used in biomedical applications, such as the detection of DNA hybridization, biomarker detection from blood, antibody detection, glucose measurement and pH sensing. The ISFET is also the basis for later BioFETs, such as the DNA field-effect transistor (DNAFET), used in genetic technology. | 0 | Theoretical and Fundamental Chemistry |
AFM-IR has been used to study miscibility and phase separation in drug polymer blends, the chemical analysis of nanocrystalline drug particles as small 90 nm across, the interaction of chromosomes with chemotherapeutics drugs, and of amyloids with pharmacological approaches to contrast neurodegeneration. | 0 | Theoretical and Fundamental Chemistry |
* A lean flashover (sometimes called rollover) is the ignition of the gas layer under the ceiling, leading to total involvement of the compartment. The air–fuel ratio is at the bottom region of the flammability range (i.e. lean).
* A rich flashover occurs when the flammable gases are ignited while at the upper region of the flammability range (i.e. rich). This can happen in rooms where the fire subsided because of lack of oxygen. The ignition source can be a smouldering object, or the stirring up of embers by the air track. Such an event is known as backdraft.
* A delayed flashover occurs when the colder gray smoke cloud ignites after congregating outside of its room of origin. This results in a volatile situation, and if the ignition occurs at the ideal mixture, the result can be a violent smoke gas explosion. This is referred to as smoke explosion or fire gas ignition depending on the severity of the combustion process.
* A hot rich flashover occurs when the hot smoke with flammable gas ratio above the upper limit of flammability range and temperature higher than the ignition temperature leaves the compartment. Upon dilution with air it can spontaneously ignite, and the resultant flame can propagate back into the compartment, resulting in an event similar to a rich flashover. The common definition of this process is known as auto-ignition, which is another form of fire gas ignition. | 0 | Theoretical and Fundamental Chemistry |
MRI has the advantages of having very high spatial resolution and is very adept at morphological imaging and functional imaging. MRI does have several disadvantages though. First, MRI has a sensitivity of around 10 mol/L mol/L which, compared to other types of imaging, can be very limiting. This problem stems from the fact that the difference between atoms in the high energy state and the low energy state is very small. For example, at 1.5 tesla, a typical field strength for clinical MRI, the difference between high and low energy states is approximately 9 molecules per 2 million. Improvements to increase MR sensitivity include increasing magnetic field strength, and hyperpolarization via optical pumping or dynamic nuclear polarization. There are also a variety of signal amplification schemes based on chemical exchange that increase sensitivity.
To achieve molecular imaging of disease biomarkers using MRI, targeted MRI contrast agents with high specificity and high relaxivity (sensitivity) are required. To date, many studies have been devoted to developing targeted-MRI contrast agents to achieve molecular imaging by MRI. Commonly, peptides, antibodies, or small ligands, and small protein domains, such as HER-2 affibodies, have been applied to achieve targeting. To enhance the sensitivity of the contrast agents, these targeting moieties are usually linked to high payload MRI contrast agents or MRI contrast agents with high relaxivities. | 1 | Applied and Interdisciplinary Chemistry |
All cloning vectors have features that allow a gene to be conveniently inserted into the vector or removed from it. This may be a multiple cloning site (MCS) or polylinker, which contains many unique restriction sites. The restriction sites in the MCS are first cleaved by restriction enzymes, then a PCR-amplified target gene also digested with the same enzymes is ligated into the vectors using DNA ligase. The target DNA sequence can be inserted into the vector in a specific direction if so desired. The restriction sites may be further used for sub-cloning into another vector if necessary.
Other cloning vectors may use topoisomerase instead of ligase and cloning may be done more rapidly without the need for restriction digest of the vector or insert. In this TOPO cloning method a linearized vector is activated by attaching topoisomerase I to its ends, and this "TOPO-activated" vector may then accept a PCR product by ligating both the 5' ends of the PCR product, releasing the topoisomerase and forming a circular vector in the process. Another method of cloning without the use of DNA digest and ligase is by DNA recombination, for example as used in the Gateway cloning system. The gene, once cloned into the cloning vector (called entry clone in this method), may be conveniently introduced into a variety of expression vectors by recombination. | 1 | Applied and Interdisciplinary Chemistry |
Eutrophication is caused by excessive concentrations of nutrients, most commonly phosphates and nitrates, although this varies with location. Prior to their being phasing out in the 1970's, phosphate-containing detergents contributed to eutrophication. Since then, sewage and agriculture have emerged as the dominant phosphate sources. The main sources of nitrogen pollution are from agricultural runoff containing fertilizers and animal wastes, from sewage, and from atmospheric deposition of nitrogen originating from combustion or animal waste.
The limitation of productivity in any aquatic system varies with the rate of supply (from external sources) and removal (flushing out) of nutrients from the body of water. This means that some nutrients are more prevalent in certain areas than others and different ecosystems and environments have different limiting factors. Phosphorus is the limiting factor for plant growth in most freshwater ecosystems, and because phosphate adheres tightly to soil particles and sinks in areas such as wetlands and lakes, due to its prevalence nowadays more and more phosphorus is accumulating inside freshwater bodies. In marine ecosystems, nitrogen is the primary limiting nutrient; nitrous oxide (created by the combustion of fossil fuels) and its deposition in the water from the atmosphere has led to an increase in nitrogen levels, and also the heightened levels of eutrophication in the ocean. | 1 | Applied and Interdisciplinary Chemistry |
An inverted siphon is not a siphon but a term applied to pipes that must dip below an obstruction to form a U-shaped flow path.
Large inverted siphons are used to convey water being carried in canals or flumes across valleys, for irrigation or gold mining. The Romans used inverted siphons of lead pipes to cross valleys that were too big to construct an aqueduct.
Inverted siphons are commonly called traps for their function in preventing sewer gases from coming back out of sewers and sometimes making dense objects like rings and electronic components retrievable after falling into a drain. Liquid flowing in one end simply forces liquid up and out the other end, but solids like sand will accumulate. This is especially important in sewerage systems or culverts which must be routed under rivers or other deep obstructions where the better term is "depressed sewer". | 1 | Applied and Interdisciplinary Chemistry |
The earliest record of trichloroethylene synthesis dates back to 1836. It was obtained from the action of potassium hydroxide on 1,1,2,2-tetrachloroethane and 1,1,1,2-tetrachloroethane by Auguste Laurent and notated as (then the atomic weight of carbon was thought to be the half of it really was). Laurent did not investigate the compound further.
Trichloroethylene's discovery is widely attributed to E. Fischer who made it in 1864 via the reduction of hexachloroethane with hydrogen. Fischer investigated TCE and noted its boiling point as between 87 and 90 degrees Celsius. Commercial production began in Germany, in 1920 and in the US in 1925.
Pioneered by Imperial Chemical Industries in Britain, under the trade name "Trilene" (from trichloroethylene) , its development was hailed as an anesthetic revolution. It was mostly known as "Trimar" in the United States. The –mar suffix indicates study and development at the University of Maryland, e.g., "Fluoromar" for fluroxene and "Vinamar" for ethyl vinyl ether".
Originally thought to possess less hepatotoxicity than chloroform, and without the unpleasant pungency and flammability of ether, TCE use was nonetheless soon found to have several pitfalls. These included promotion of cardiac arrhythmias, low volatility and high solubility preventing quick anesthetic induction, reactions with soda lime used in carbon dioxide absorbing systems, prolonged neurologic dysfunction when used with soda lime, and evidence of hepatotoxicity as had been found with chloroform.
The introduction of halothane in 1956 greatly diminished the use of TCE as a general anesthetic. TCE was still used as an inhalation analgesic in childbirth given by self-administration. Fetal toxicity and concerns about the carcinogenic potential of TCE led to its abandonment in developed countries by the 1980s.
The use of trichloroethylene in the food and pharmaceutical industries has been banned in much of the world since the 1970s due to concerns about its toxicity. Legislation has forced the replacement of trichloroethylene in many processes in Europe as the chemical was classified as a carcinogen carrying an R45 risk phrase, May cause cancer. Many degreasing chemical alternatives are being promoted such as Ensolv and Leksol; however, each of these is based on n-propyl bromide which carries an R60 risk phrase of May impair fertility, and would not be a legally acceptable substitute. | 1 | Applied and Interdisciplinary Chemistry |
An inverted repeat (or IR) is a single stranded sequence of nucleotides followed downstream by its reverse complement. The intervening sequence of nucleotides between the initial sequence and the reverse complement can be any length including zero. For example, is an inverted repeat sequence. When the intervening length is zero, the composite sequence is a palindromic sequence.
Both inverted repeats and direct repeats constitute types of nucleotide sequences that occur repetitively. These repeated DNA sequences often range from a pair of nucleotides to a whole gene, while the proximity of the repeat sequences varies between widely dispersed and simple tandem arrays. The short tandem repeat sequences may exist as just a few copies in a small region to thousands of copies dispersed all over the genome of most eukaryotes. Repeat sequences with about 10–100 base pairs are known as minisatellites, while shorter repeat sequences having mostly 2–4 base pairs are known as microsatellites. The most common repeats include the dinucleotide repeats, which have the bases AC on one DNA strand, and GT on the complementary strand. Some elements of the genome with unique sequences function as exons, introns and regulatory DNA. Though the most familiar loci of the repetitive sequences are the centromere and the telomere, a large portion of the repeated sequences in the genome are found among the noncoding DNA.
Inverted repeats have a number of important biological functions. They define the boundaries in transposons and indicate regions capable of self-complementary base pairing (regions within a single sequence which can base pair with each other). These properties play an important role in genome instability and contribute not only to cellular evolution and genetic diversity but also to mutation and disease. In order to study these effects in detail, a number of programs and databases have been developed to assist in discovery and annotation of inverted repeats in various genomes. | 1 | Applied and Interdisciplinary Chemistry |
Retrosynthetic analysis is a technique for solving problems in the planning of organic syntheses. This is achieved by transforming a target molecule into simpler precursor structures regardless of any potential reactivity/interaction with reagents. Each precursor material is examined using the same method. This procedure is repeated until simple or commercially available structures are reached. These simpler/commercially available compounds can be used to form a synthesis of the target molecule. E.J. Corey formalized this concept in his book The Logic of Chemical Synthesis.
The power of retrosynthetic analysis becomes evident in the design of a synthesis. The goal of retrosynthetic analysis is a structural simplification. Often, a synthesis will have more than one possible synthetic route. Retrosynthesis is well suited for discovering different synthetic routes and comparing them in a logical and straightforward fashion. A database may be consulted at each stage of the analysis, to determine whether a component already exists in the literature. In that case, no further exploration of that compound would be required. If that compound exists, it can be a jumping point for further steps developed to reach a synthesis. | 0 | Theoretical and Fundamental Chemistry |
Triphenyl tetrazolium chloride, TTC, or simply tetrazolium chloride (with the formula 2,3,5-triphenyl-2H-tetrazolium chloride) is a redox indicator commonly used in biochemical experiments especially to indicate cellular respiration. It is a white crystalline powder, soluble in water, ethanol and acetone but insoluble in ether. | 0 | Theoretical and Fundamental Chemistry |
There are various treatments to combat the effects of nonivamide. One popular method includes administering a one to one solution of milk of magnesia, and water to the eyes. Doctors also recommend not using oils or creams on the skin, and to not wear contact lenses, if one is planning to minimise the effects of nonivamide. | 1 | Applied and Interdisciplinary Chemistry |
The average grade of copper ores in the 21st century is below 0.6% copper, with a proportion of economic ore minerals being less than 2% of the total volume of the ore rock. Thus, all mining operations, the ore must usually be beneficiated (concentrated). The concentrate is typically sold to distant smelters, although some large mines have smelters located nearby. Such colocation of mines and smelters was more typical in the 19th and early 20th centuries, when smaller smelters could be economic. The subsequent processing techniques depend on the nature of the ore.
In the usual case when it is primarily sulfide copper minerals (such as chalcopyrite, FeCuS), the ore is treated by comminution, where the rock is crushed to produce small particles (<100 μm) consisting of individual mineral phases. These particles are then ready to be separated to remove gangue (silicate rocks residues) using froth flotation. | 1 | Applied and Interdisciplinary Chemistry |
Murexide is used in analytical chemistry as a complexometric indicator for complexometric titrations, most often of calcium ions, but also for copper, nickel, cobalt, thorium and rare-earth metals. It functions as a tridentate ligand.
Its use has been eclipsed by calcium-ion selective electrodes. | 0 | Theoretical and Fundamental Chemistry |
Attaching a single polymer chain to a specific site away from the active center of the protein has less impact on protein activity compared with random attachments. In practice, attaching a single polymer chain can be used to adjust chemical properties of the therapeutic protein. For example, conjugation of a single chain of the hydrophilic polyethylene glycol (PEG) can increase the hydrodynamic radius of the protein conjugate by 5-10 fold. Attachment to PEG was mainly achieved by covalent conjugation via the grafting to strategy, targeting chemo-selective anchor groups. Other polymers, such as oligosaccharides and polypeptides, offer different properties to the enzymes attached to them. | 1 | Applied and Interdisciplinary Chemistry |
Flower visitors such as insects and bats detect floral scents thanks to chemoreceptors of variable specificity to a specific VOC. The fixation of a VOC on a chemoreceptor triggers the activation of an antennal glomerulus, further projecting on an olfactory receptor neuron and finally triggering a behavioral response after processing the information (see also Olfaction, Insect olfaction). The simultaneous perception of various VOCs may cause the activation of several glomeruli, but the output signal may not be additive due to synergistic or antagonistic mechanisms linked with inter-neuronal activity. Therefore, the perception of a VOC within a floral blend may trigger a different behavioral response than when perceived isolated. Similarly, the output signal is not proportional to the amount of VOCs, with some VOCs in low amounts in the floral blend having major effects on pollinator behavior. A good characterization of floral scent, both qualitative and quantitative, is necessary to understand and potentially predict flower visitors' behavior.
Flower visitors use floral scents to detect, recognize and locate their host species and even discriminate among flowers of the same plant. This is made possible by the high specificity of floral scent, where both diversity of VOCs and their relative amount may characterize the flowering species, an individual plant, a flower of the plant, and the distance of the plume from the source.
To make the best use of this specific information, flower visitors rely on long-term and short-term memory that allows them to efficiently choose their flowers. They learn to associate the floral scent of a plant with a reward such as nectar and pollen, and have different behavioral responses to known scents versus unknown ones. They are also able to react similarly to slightly different odor blends. | 1 | Applied and Interdisciplinary Chemistry |
Many problems in the chemical and physical sciences can be related to packing problems where more than one size of sphere is available. Here there is a choice between separating the spheres into regions of close-packed equal spheres, or combining the multiple sizes of spheres into a compound or interstitial packing. When many sizes of spheres (or a distribution) are available, the problem quickly becomes intractable, but some studies of binary hard spheres (two sizes) are available.
When the second sphere is much smaller than the first, it is possible to arrange the large spheres in a close-packed arrangement, and then arrange the small spheres within the octahedral and tetrahedral gaps. The density of this interstitial packing depends sensitively on the radius ratio, but in the limit of extreme size ratios, the smaller spheres can fill the gaps with the same density as the larger spheres filled space. Even if the large spheres are not in a close-packed arrangement, it is always possible to insert some smaller spheres of up to 0.29099 of the radius of the larger sphere.
When the smaller sphere has a radius greater than 0.41421 of the radius of the larger sphere, it is no longer possible to fit into even the octahedral holes of the close-packed structure. Thus, beyond this point, either the host structure must expand to accommodate the interstitials (which compromises the overall density), or rearrange into a more complex crystalline compound structure. Structures are known which exceed the close packing density for radius ratios up to 0.659786.
Upper bounds for the density that can be obtained in such binary packings have also been obtained.
In many chemical situations such as ionic crystals, the stoichiometry is constrained by the charges of the constituent ions. This additional constraint on the packing, together with the need to minimize the Coulomb energy of interacting charges leads to a diversity of optimal packing arrangements. | 0 | Theoretical and Fundamental Chemistry |
Gastric- and lingual lipases are the two acidic lipolytic enzymes that origin preduodenal but the gastric lipase is in much higher levels in humans.
Gastric lipase is synthesized and secreted from gastric chief cells in the stomach and is stable at pH 1,5-8,
but has maximum activity at pH 3-6.
Fat digestion begins when gastric lipase hydrolyses dietary triglycerides, by cleaving only one long-, medium- or short-acyl chain from the glyceride backbone and release free fatty acids and diacylglycerols. The enzyme hydrolyses esters at position sn-3, the acyl chain at the bottom, more rapidly than esters at sn-1 position, the acyl chain on the top of the glyceride backbone. However the gastric lipase activity against phospholipids and cholesterol esters is poor.
Gastric lipase is composed of 379 amino acids. Fully glycosylated protein is 50kDa and unglycosylated enzyme is 43kDa. However deglycosylation of the enzyme does not affect the activity of the enzyme. The hydrophobic region around Ser152, which has the hexapeptide sequence Val-Gly-His-Ser-Gln-Gly, is essential for the catalytic activity of gastric lipase. At the N-terminal, Lys4 is necessary for the enzyme to bind at lipid-water interfaces. | 1 | Applied and Interdisciplinary Chemistry |
Ester exchange takes place between an ester carbonyl and an alcohol. Reverse esterification can take place via hydrolysis. This method has been used extensively in polymer synthesis. | 0 | Theoretical and Fundamental Chemistry |
This way also uses two experimental protocols, and , to compare the index effect with the effect of moderation alone. The index protocol is executed first; the response of prime interest, is observed, and the response of the moderating variable is also measured. With that knowledge, then the fixed driver, moderation imposed protocol enforces that with the driving variable held fixed; the protocol also, through an adjustment imposes a change (learnt from the just previous measurement) in the moderating variable, and measures the change Provided that the moderated response is indeed that then the principle states that the signs of and are opposite.
Again, in other words, change in the moderating state variable opposes the effect of the driving change in on the responding conjugate variable | 0 | Theoretical and Fundamental Chemistry |
* Directed Placement – Directly print various materials onto existing nano and microstructures with nanoscale registry
* Direct Write – Maskless creation of arbitrary patterns with feature resolutions from as small as 50 nm and as large as 10 micrometres
* Biocompatible – Subcellular to nanoscale resolution at ambient deposition conditions
* Scalable – Force independent, allowing for parallel depositions | 1 | Applied and Interdisciplinary Chemistry |
The Staudinger reduction is conducted in two steps. First phosphine imine-forming reaction is conducted involving treatment of the azide with the phosphine. The intermediate, e.g. triphenylphosphine phenylimide, is then subjected to hydrolysis to produce a phosphine oxide and an amine:
:RP=NR + HO → RP=O + RNH
The overall conversion is a mild method of reducing an azide to an amine. Triphenylphosphine or tributylphosphine are most commonly used, yielding tributylphosphine oxide or triphenylphosphine oxide as a side product in addition to the desired amine. An example of a Staudinger reduction is the organic synthesis of the pinwheel compound 1,3,5-tris(aminomethyl)-2,4,6-triethylbenzene. | 0 | Theoretical and Fundamental Chemistry |
It creates volatile compounds when mixed with glucose and amino acids at 90 °C.
It is a cofactor in tyrosine oxidation. | 1 | Applied and Interdisciplinary Chemistry |
Brine rejection occurs in the sea ice packs around at the north and south poles of the Earth. The Arctic Ocean has historically ranged from roughly 14-16 million square kilometers in late winter to roughly 7 million km each September. The annual increase of ice plays a major role in the movement of ocean circulation and deep water formation. The density of the water below the newly-formed ice increases due to brine rejection. Saltier water can also become colder without freezing.
The dense water that forms in the Arctic are called North Atlantic Deep Water (NADW), while the Antarctic Bottom Water (AABW) forms in the southern hemisphere. These two areas of brine rejection play an important role in the thermohaline circulation of all of Earth's oceans. | 0 | Theoretical and Fundamental Chemistry |
Bis(chloromethyl) ether is an organic compound with the chemical formula (ClCH)O. It is a colourless liquid with an unpleasant suffocating odour and it is one of the chloroalkyl ethers. Bis(chloromethyl) ether was once produced on a large scale, but was found to be highly carcinogenic and thus such production has ceased. | 0 | Theoretical and Fundamental Chemistry |
CRISPR gene editing based on Clustered regularly interspaced short palindromic repeats (CRISPR) -Cas9 is an enzyme that uses the gene sequences to help control, cleave, and separate specific DNA sequences that are complementary to a CRISPR sequence. These sequences and enzymes were originally derived from bacteriophages. The importance of this technique in the field of genetic engineering is that it gives the ability to have highly precise targeted gene editing and the cost factor for this technique is low compared to other tools. The ability to insert DNA sequences into the organism is easy and fast, although it can run into expression issues in higher complex organisms. | 1 | Applied and Interdisciplinary Chemistry |
Hardy worked as assistant professor of organic chemistry at Bryn Mawr College in 1939 and 1940. In the years 1942–1958, Hardy worked as a chemist at Calco Chemical Division, subsequently she worked as a literature chemist at Lederle Labs from 1958 to 1975. After working for Lederle, Hardy worked as a senior resident literature chemist for American Cyanamid Company from 1975 on. She was a member of the American Association for the Advancement of Science, American Chemical Society and Chemical Institute of Canada. Hardy worked in a number of different research areas including molecular rearrangements, preparation of unsaturated esters and ketones, vat dyestuffs, esterification of leuco vat dyes, organosulfur compounds, and pharmaceutical chemistry. | 0 | Theoretical and Fundamental Chemistry |
In its simplest form, equilibrium unfolding assumes that the molecule may belong to only two thermodynamic states, the folded state (typically denoted N for "native" state) and the unfolded state (typically denoted U). This "all-or-none" model of protein folding was first proposed by Tim Anson in 1945, but is believed to hold only for small, single structural domains of proteins (Jackson, 1998); larger domains and multi-domain proteins often exhibit intermediate states. As usual in statistical mechanics, these states correspond to ensembles of molecular conformations, not just one conformation.
The molecule may transition between the native and unfolded states according to a simple kinetic model
:N U
with rate constants and for the folding () and unfolding () reactions, respectively. The dimensionless equilibrium constant can be used to determine the conformational stability by the equation
where is the gas constant and is the absolute temperature in kelvin. Thus, is positive if the unfolded state is less stable (i.e., disfavored) relative to the native state.
The most direct way to measure the conformational stability of a molecule with two-state folding is to measure its kinetic rate constants and under the solution conditions of interest. However, since protein folding is typically completed in milliseconds, such measurements can be difficult to perform, usually requiring expensive stopped flow or (more recently) continuous-flow mixers to provoke folding with a high time resolution. Dual polarisation interferometry is an emerging technique to directly measure conformational change and . | 0 | Theoretical and Fundamental Chemistry |
Especially energetic alpha particles deriving from a nuclear process are produced in the relatively rare (one in a few hundred) nuclear fission process of ternary fission. In this process, three charged particles are produced from the event instead of the normal two, with the smallest of the charged particles most probably (90% probability) being an alpha particle. Such alpha particles are termed "long range alphas" since at their typical energy of 16 MeV, they are at far higher energy than is ever produced by alpha decay. Ternary fission happens in both neutron-induced fission (the nuclear reaction that happens in a nuclear reactor), and also when fissionable and fissile actinides nuclides (i.e., heavy atoms capable of fission) undergo spontaneous fission as a form of radioactive decay. In both induced and spontaneous fission, the higher energies available in heavy nuclei result in long range alphas of higher energy than those from alpha decay. | 0 | Theoretical and Fundamental Chemistry |
Acute beryllium poisoning is an occupational disease. Relevant occupations are those where beryllium is mined, processed or converted into metal alloys, or where machining of metals containing beryllium or recycling of scrap alloys occurs.
Metallographic preparation equipment and laboratory work surfaces must be damp-wiped occasionally to inhibit buildup of particles. Cutting, grinding, and polishing procedures that generate dust or fumes must be handled within sufficiently vented coverings supplied with particulate filters. | 1 | Applied and Interdisciplinary Chemistry |
Most of the time, artificial tissue is grown from the patients own cells. However, when the damage is so extreme that it is impossible to use the patients own cells, artificial tissue cells are grown. The difficulty is in finding a scaffold that the cells can grow and organize on. The characteristics of the scaffold must be that it is biocompatible, cells can adhere to the scaffold, mechanically strong and biodegradable. One successful scaffold is a copolymer of lactic acid and glycolic acid. | 1 | Applied and Interdisciplinary Chemistry |
George N. Phillips Jr. is a biochemist, researcher, and academic. He is the Ralph and Dorothy Looney Professor of Biochemistry and Cell Biology at Rice University, where he also serves as Associate Dean for Research at the Wiess School of Natural Sciences and as a professor of chemistry. Additionally, he holds the title of professor emeritus of biochemistry at the University of Wisconsin-Madison.
Phillips research is primarily centered on protein structure, protein dynamics, and computational biology, with a specific emphasis on understanding the correlation between the dynamics of proteins and their biological functions. He has authored book chapters, and is an editor for the Handbook of Proteins: Structure, Function and Methods Volume 2. He is the recipient of the Arnold O. Beckman Research Award, the American Heart Associations Established Investigator Award, and the Vilas Associate Award.
Phillips is an Elected Fellow of the Biophysical Society, the American Crystallographic Association, and the American Association for the Advancement of Science. He served as president and vice-president of the American Crystallographic Association from 2011 to 2013. He also holds the position of Editor-in-Chief for Structural Dynamics with the AIP Press and serves as an Associate Editor for Critical Reviews in Biochemistry and Molecular Biology. | 1 | Applied and Interdisciplinary Chemistry |
Initially written off as a non-essential process due to the ATE1 knockout in yeast, later studies have shown arginylation plays a significant role in several biological processes. The knockout of ATE1 in mice and Drosophila resulted in embryonic lethality for both species. Further studies using the mouse model to observe the effects of ATE1 knockout in the development of the organism revealed that the gene loss resulted in abnormal cardiac and craniofacial morphogenesis, impaired angiogenesis, and the ability of cells to undergo meiosis. Postnatally, ATE1 knockout resulted in weight loss, infertility, and mental retardation. Additionally, observing the effects of ATE1 deletion in Arabidopsis thaliana, a model plant organism, revealed defective shoot and leaf development, abnormal seed germination, and delayed leaf senescence. The dysfunctions resulting from the knockout of the ATE1 enzyme therefore suggest that arginylation is necessary for many physiological pathways within eukaryotes. | 1 | Applied and Interdisciplinary Chemistry |
The conjugate base of a sulfinic acid is a sulfinate anion. The enzyme cysteine dioxygenase converts cysteine into the corresponding sulfinate. One product of this catabolic reaction is the sulfinic acid hypotaurine. Sulfinite also describes esters of sulfinic acid. Cyclic sulfinite esters are called sultines. | 0 | Theoretical and Fundamental Chemistry |
The Italian company Caffaro, located in Brescia, specialized in producing PCBs from 1938 to 1984, following the acquisition of the exclusive rights to use the patent in Italy from Monsanto. The pollution resulting from this factory and the case of Anniston, in the US, are the largest known cases in the world of PCB contamination in water and soil, in terms of the amount of toxic substance dispersed, size of the area contaminated, number of people involved and duration of production.
The values reported by the local health authority (ASL) of Brescia since 1999 are 5,000 times above the limits set by Ministerial Decree 471/1999 (levels for residential areas, 0.001 mg/kg). As a result of this and other investigations, in June 2001, a complaint of an environmental disaster was presented to the Public Prosecutors Office of Brescia. Research on the adult population of Brescia showed that residents of some urban areas, former workers of the plant, and consumers of contaminated food, have PCB levels in their bodies that are in many cases 10–20 times higher than reference values in comparable general populations. PCBs entered the human food supply by animals grazing on contaminated pastures near the factory, especially in local veal mostly eaten by farmers families. The exposed population showed an elevated risk of Non-Hodgkin lymphoma, but not for other specific cancers. | 1 | Applied and Interdisciplinary Chemistry |
Iron isotopes have become particularly useful in recent years for tracing biogeochemical cycling in the oceans. Iron is an important micronutrient for living species in the ocean, particularly for the growth of phytoplankton. Iron is estimated to limit phytoplankton growth in about one half of the ocean. As a result, the development of a better understanding of sources and cycling of iron in the modern oceans is important. Iron isotopes have been used to better constrain these pathways through data collected by the GEOTRACES program, which has collected iron isotopic data throughout the ocean. Based on the variations in iron isotopes, biogeochemical cycling and other processes controlling iron distribution in the ocean can be elucidated.
For example, the combination of iron concentration and iron isotope data can use to determine the sources of oceanic iron. In the South Atlantic and in the Southern Ocean, isotopically light iron is observed in intermediate waters (200 - 1,300 meters), whereas isotopically heavy iron is observed in surface waters and deep waters (> 1,300 meters). To first order, this demonstrates that there are different sources, sinks, and processes contributing to the iron cycle in varying water masses. The isotopically light iron in intermediate waters suggests that the dominant iron sources include remineralized organic matter. This organic matter is isotopically light because phytoplankton preferentially take up light iron. In the surface ocean, the isotopically heavy iron represents the external sources of iron, such as dust, which is isotopically heavy relative to IRMM-014, and the sink of light isotopes as a result of their preferential uptake by phytoplankton. The isotopically heavy iron in the deep ocean suggests that the iron cycle is dominated by the abiotic, non-reductive release of iron, via desorption or dissolution, from particles. Isotopic analyses similar to the one above are utilized throughout all of the world's oceans to better understand regional variability in the processes which control iron cycling. These analyses can then be synthesized to better model the global biogeochemical cycling of iron, which is particularly important when considering primary production in the ocean. | 0 | Theoretical and Fundamental Chemistry |
Mucolipin-1 also known as TRPML1 (transient receptor potential cation channel, mucolipin subfamily, member 1) is a protein that in humans is encoded by the MCOLN1 gene. It is a member of the small family of the TRPML channels, a subgroup of the large protein family of TRP ion channels.
TRPML1 is a 65 kDa protein associated with mucolipidosis type IV. Its predicted structure includes six transmembrane domains, a transient receptor potential (TRP) cation-channel domain, and an internal channel pore. TRPML1 is believed to channel iron ions across the endosome/lysosome membrane into the cell and so its malfunction causes cellular iron deficiency. It is important in lysosome function and plays a part in processes such as vesicular trafficking, exocytosis and autophagy. | 1 | Applied and Interdisciplinary Chemistry |
Cell metabolism is necessary for the production of energy for the cell and therefore its survival and includes many pathways and also sustaining the main cell organelles such as the nucleus, the mitochondria, the cell membrane etc. For cellular respiration, once glucose is available, glycolysis occurs within the cytosol of the cell to produce pyruvate. Pyruvate undergoes decarboxylation using the multi-enzyme complex to form acetyl coA which can readily be used in the TCA cycle to produce NADH and FADH. These products are involved in the electron transport chain to ultimately form a proton gradient across the inner mitochondrial membrane. This gradient can then drive the production of ATP and during oxidative phosphorylation. Metabolism in plant cells includes photosynthesis which is simply the exact opposite of respiration as it ultimately produces molecules of glucose. | 1 | Applied and Interdisciplinary Chemistry |
Heavy liquids such as tetrabromoethane can be used to separate ores from supporting rocks by preferential flotation. The rocks are crushed, and while sand, limestone, dolomite, and other types of rock material will float on TBE, ores such as sphalerite, galena and pyrite will sink. | 0 | Theoretical and Fundamental Chemistry |
Alpha decay is characterized by the emission of an alpha particle, a He nucleus. The mode of this decay causes the parent nucleus to decrease by two protons and two neutrons. This type of decay follows the relation: | 0 | Theoretical and Fundamental Chemistry |
An exponential decay can be described by any of the following four equivalent formulas:<big><math display="block">\begin{align}
N(t) &= N_0 \left(\frac {1}{2}\right)^{\frac{t}{t_{1/2}}} \\
N(t) &= N_0 2^{-\frac{t}{t_{1/2}}} \\
N(t) &= N_0 e^{-\frac{t}{\tau}} \\
N(t) &= N_0 e^{-\lambda t}
\end{align}
where
* is the initial quantity of the substance that will decay (this quantity may be measured in grams, moles, number of atoms, etc.),
* is the quantity that still remains and has not yet decayed after a time ,
* is the half-life of the decaying quantity,
* is a positive number called the mean lifetime of the decaying quantity,
* is a positive number called the decay constant of the decaying quantity.
The three parameters , , and are directly related in the following way:where is the natural logarithm of 2 (approximately 0.693). | 0 | Theoretical and Fundamental Chemistry |
The triangle of death () is an area approximately 25 km northeast of the city of Naples in the Province of Naples, Campania, Italy, that comprises the comuni of Acerra, Nola and Marigliano. This area contains the largest illegal waste dump in Europe due to a waste management crisis in the 1990s and 2000s.
The region has experienced a rise in cancer-related mortality that is linked to exposure of pollution from the illegal waste disposal by the Camorra criminal organization after regional landfills had been filled to capacity.
The phenomenon of widespread environmental crime perpetrated by criminal syndicates like the Camorra and 'Ndrangheta has given rise to the term "ecomafia". | 1 | Applied and Interdisciplinary Chemistry |
Alcohols alkylate to give ethers:
When the alkylating agent is an alkyl halide, the conversion is called the Williamson ether synthesis.
Alcohols are also good alkylating agents in the presence of suitable acid catalysts. For example, most methyl amines are prepared by alkylation of ammonia with methanol. The alkylation of phenols is particularly straightforward since it is subject to fewer competing reactions.
:(with as a spectator ion)
More complex alkylation of a alcohols and phenols involve ethoxylation. Ethylene oxide is the alkylating group in this reaction. | 0 | Theoretical and Fundamental Chemistry |
Because there is a difference in concentration of ions on either side of the membrane, the pH (defined using the relative activity) may also differ when protons are involved. In many instances, from ultrafiltration of proteins to ion exchange chromatography, the pH of the buffer adjacent to the charged groups of the membrane is different from the pH of the rest of the buffer solution. When the charged groups are negative (basic), then they will attract protons so that the pH will be lower than the surrounding buffer. When the charged groups are positive (acidic), then they will repel protons so that the pH will be higher than the surrounding buffer. | 0 | Theoretical and Fundamental Chemistry |
Surveys showed that 54% of lakes in Asia are eutrophic; in Europe, 53%; in North America, 48%; in South America, 41%; and in Africa, 28%. In South Africa, a study by the CSIR using remote sensing has shown more than 60% of the reservoirs surveyed were eutrophic.
The World Resources Institute has identified 375 hypoxic coastal zones in the world, concentrated in coastal areas in Western Europe, the Eastern and Southern coasts of the US, and East Asia, particularly Japan. | 1 | Applied and Interdisciplinary Chemistry |
Andrei Sakharov and F.C. Frank predicted the phenomenon of muon-catalyzed fusion on theoretical grounds before 1950. Yakov Borisovich Zeldovich also wrote about the phenomenon of muon-catalyzed fusion in 1954. Luis W. Alvarez et al.', when analyzing the outcome of some experiments with muons incident on a hydrogen bubble chamber at Berkeley in 1956, observed muon-catalysis of exothermic p–d, proton and deuteron, nuclear fusion, which results in a helion, a gamma ray, and a release of about 5.5 MeV of energy. The Alvarez experimental results, in particular, spurred John David Jackson to publish one of the first comprehensive theoretical studies of muon-catalyzed fusion in his ground-breaking 1957 paper. This paper contained the first serious speculations on useful energy release from muon-catalyzed fusion. Jackson concluded that it would be impractical as an energy source, unless the "alpha-sticking problem" (see below) could be solved, leading potentially to an energetically cheaper and more efficient way of utilizing the catalyzing muons. | 0 | Theoretical and Fundamental Chemistry |
Some viral families, such as the Bromoviridae instead opt to have multipartite genomes, genomes split between multiple viral particles. For infection to occur, the plant must be infected with all particles across the genome. For instance Brome mosaic virus has a genome split between 3 viral particles, and all 3 particles with the different RNAs are required for infection to take place. | 1 | Applied and Interdisciplinary Chemistry |
Surface modification has gained a lot of interest in recent years for a variety of applications. An example of the application of free radical polymerizations to forming new architectures is through RAFT polymerizations which result in dithioester end groups. These dithioesters can be reduced to the thiol which can be immobilized on a metal surface; this is important for applications in electronics, sensing and catalysis. The schematic below demonstrates the immobilization of copolymers onto a gold surface as reported for poly(sodium 4-styrenesulfonate) by the McCormick group at the University of Southern Mississippi. | 0 | Theoretical and Fundamental Chemistry |
Meteorites come in a variety of compositions, but chemical analysis can determine whether they were once in planetesimals that melted or differentiated. Chondrites are undifferentiated and have round mineral inclusions called chondrules. With the ages of 4.56 billion years, they date to the early solar system. A particular kind, the CI chondrite, has a composition that closely matches that of the Sun's photosphere, except for depletion of some volatiles (H, He, C, N, O) and a group of elements (Li, B, Be) that are destroyed by nucleosynthesis in the Sun. Because of the latter group, CI chondrites are considered a better match for the composition of the early Solar System. Moreover, the chemical analysis of CI chondrites is more accurate than for the photosphere, so it is generally used as the source for chemical abundance, despite their rareness (only five have been recovered on Earth). | 0 | Theoretical and Fundamental Chemistry |
More than 600 million SNPs have been identified across the human genome in the world's population. A typical genome differs from the reference human genome at 4 to 5 million sites, most of which (more than 99.9%) consist of SNPs and short indels. | 1 | Applied and Interdisciplinary Chemistry |
In physics, an atomic mirror is a device which reflects neutral atoms in a way similar to the way a conventional mirror reflects visible light. Atomic mirrors can be made of electric fields or magnetic fields, electromagnetic waves or just silicon wafer; in the last case, atoms are reflected by the attracting tails of the van der Waals attraction (see quantum reflection). Such reflection is efficient when the normal component of the wavenumber of the atoms is small or comparable to the effective depth of the attraction potential (roughly, the distance at which the potential becomes comparable to the kinetic energy of the atom). To reduce the normal component, most atomic mirrors are blazed at the grazing incidence.
At grazing incidence, the efficiency of the quantum reflection can be enhanced by a surface covered with ridges (ridged mirror).
The set of narrow ridges reduces the van der Waals attraction of atoms to the surfaces and enhances the reflection. Each ridge blocks part of the wavefront, causing Fresnel diffraction.
Such a mirror can be interpreted in terms of the Zeno effect.
We may assume that the atom is "absorbed" or "measured" at the ridges. Frequent measuring (narrowly spaced ridges) suppresses the transition of the particle to the half-space with absorbers, causing specular reflection. At large separation between thin ridges, the reflectivity of the ridged mirror is determined by dimensionless momentum , and does not depend on the origin of the wave; therefore, it is suitable for reflection of atoms. | 0 | Theoretical and Fundamental Chemistry |
Directing edits to correct mutated sequences was first proposed and demonstrated in 1995. This initial work used synthetic RNA antisense oligonucleotides complementary to a pre-mature stop codon mutation in a dystrophin sequence to activate A-to-I editing of the stop codon to a read through codon in a model xenopus cell system. While this also led to nearby inadvertent A-to-I transitions, A to I (read as G) transitions can correct all three stop codons, but cannot create a stop codon. Therefore, the changes led >25% correction of the targeted stop codon with read through to a downstream luciferase reporter sequence. Follow on work by Rosenthal achieved editing of mutated mRNA sequence in mammalian cell culture by directing an oligonucleotide linked to a cytidine deaminase to correct a mutated cystic fibrosis sequence. More recently, CRISPR-Cas13 fused to deaminases has been employed to direct mRNA editing.
In 2022, therapeutic RNA editing for Cas7-11 was reported. It enables sufficiently targeted cuts and an early version of it was used for in vitro editing in 2021. | 1 | Applied and Interdisciplinary Chemistry |
High voltage distribution networks use fixed electrolyte resistors to ground the neutral, to provide a current limiting action, so that the voltage across the ground during fault is kept to a safe level. Unlike a solid resistor, the liquid resistor is self healing in the event of overload. Normally the resistance is set up during commissioning, and then left fixed.
Modern motor starters are totally enclosed and the electrode movement is servo motor controlled. Typically a 1 tonne tank will start a 1 megawatt slip ring type motor, but there is considerable variation in start time depending on application. | 0 | Theoretical and Fundamental Chemistry |
ITCH is regulated by MAPK8. MAPK8 regulates JUNB protein turnover by MAPK8-dependent phosphorylation of ITCH and a subsequent conformational change in ITCH. This mechanism is discrete from the direct activation of Jun family transcription factors by direct phosphorylation. ITCH serves as a paradigm for our understanding of the regulation of the ubiquitylation machinery by direct protein phosphorylation of its components. Importantly, this regulatory process controls the balance of Th2 cytokine secretion by negatively regulating JUNB levels and Interleukin 4 transcription. | 1 | Applied and Interdisciplinary Chemistry |
Acquisition, adaptive re-use, and disposal of a brownfield site requires advanced and specialized appraisal analysis techniques. For example, the highest and best use of the brownfield site may be affected by the contamination, both before and after remediation. Additionally, the value should take into account residual stigma and potential for third-party liability. Normal appraisal techniques frequently fail, and appraisers must rely on more advanced techniques, such as contingent valuation, case studies, or statistical analyses. A 2011 University of Delaware study has suggested a 17.5:1 return on dollars invested on brownfield redevelopment.
A 2014 study of EPA brownfield cleanup grants from 2002 through 2008 found an average benefit value of almost $4 million per brownfield site (with a median of $2,117,982).
To expedite the cleanup of brownfield sites in the US, some environmental firms have teamed up with insurance companies to underwrite the cleanup and provide a guaranteed cleanup cost to limit land developers' exposure to environmental remediation costs and pollution lawsuits. The environmental firm first performs an extensive investigation generally in the form of desk studies and potentially further intrusive investigation. | 1 | Applied and Interdisciplinary Chemistry |
Spalling is a common mechanism of rock weathering, and occurs at the surface of a rock when there are large shear stresses under the surface. This form of mechanical weathering can be caused by freezing and thawing, unloading, thermal expansion and contraction, or salt deposition. | 1 | Applied and Interdisciplinary Chemistry |
Abortive initiation is a normal process of transcription and occurs both in vitro and in vivo. After each nucleotide-addition step in initial transcription, RNA polymerase, stochastically, can proceed on the pathway toward promoter escape (productive initiation) or can release the RNA product and revert to the RNA polymerase-promoter open complex (abortive initiation). During this early stage of transcription, RNA polymerase enters a phase during which dissociation of the transcription complex energetically competes with the elongation process. Abortive cycling is not caused by strong binding between the initiation complex and the promoter. | 1 | Applied and Interdisciplinary Chemistry |
Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) is often used in organic electrons and have strong NIR absorption. In 2012, Liu’s group first reported PEGylated PEDOT:PSS polymeric nanoparticle (PEDOT:PSS-PEG) for near-infrared photothermal therapy of cancer. PEDOT:PSS-PEG nanoparticles have high stability in vivo and long blood circulation half-life of 21.4 ± 3.1 h. The PTT in animals showed no appreciable side effects for the tested dose and an excellent therapeutic efficacy under the 808 nm laser irradiation. Kang et al. synthesized magneto-conjugated polymer core−shell MNP@PEDOT:PSS nanoparticles for multimodal imaging-guided PTT. Furthermore, PEDOT:PSS NPs can not only serve as PTAs but also as a drug carrier to load various types of drugs, such as SN38, chemotherapy drugs DOX and photodynamic agent chlorin e6 (Ce6), thus achieving synergistic cancer therapy. | 0 | Theoretical and Fundamental Chemistry |
In enzymology, a NAD glycohydrolase () is an enzyme that catalyzes the chemical reaction
:NAD + HO ADP-ribose + nicotinamide
Thus, the two substrates of this enzyme are NAD and HO, whereas its two products are ADP-ribose and nicotinamide. Unlike ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase (EC 3.2.2.6), which catalyzes the same reaction, this reaction does not proceed through a cyclic ADP-ribose.
This enzyme belongs to the family of hydrolases, specifically those glycosylases that hydrolyse N-glycosyl compounds. The systematic name of this enzyme class is NAD glycohydrolase. Other names in common use include NAD+ nucleosidase, NADase, DPNase, DPN hydrolase, NAD hydrolase, diphosphopyridine nucleosidase, nicotinamide adenine dinucleotide nucleosidase, NAD glycohydrolase, NAD nucleosidase, and nicotinamide adenine dinucleotide glycohydrolase. This enzyme participates in nicotinate and nicotinamide metabolism and calcium signaling pathway. Calcium metabolism involves the regulation of the levels of calcium in the body. The role this calcium plays also includes providing enough calcium for bone mineralization. It serves as the basis for the structure and rigidity of bones. Calcium metabolism can lead to a variety of diseases which can involve renal function. High concentrations of calcium can lead to cell death or apoptosis. | 1 | Applied and Interdisciplinary Chemistry |
The hydrolysis of nitriles is conducted on an industrial scale to produce fatty amides. Laboratory procedures are also available. | 0 | Theoretical and Fundamental Chemistry |
The hypersalinity and high alkalinity (pH=10 or equivalent to 4 milligrams of NaOH per liter of water) of the lake means that no fish are native to the lake. An attempt by the California Department of Fish and Game to stock the lake failed.
The whole food chain of the lake is based on the high population of single-celled planktonic algae present in the photic zone of the lake. These algae reproduce rapidly during winter and early spring after winter runoff brings nutrients to the surface layer of water. By March the lake is "as green as pea soup" with photosynthesizing algae.
The lake is famous for the Mono Lake brine shrimp, Artemia monica, a tiny species of brine shrimp, no bigger than a thumbnail, that are endemic to the lake. During the warmer summer months, an estimated 4–6 trillion brine shrimp inhabit the lake. Brine shrimp have no food value for humans, but are a staple for birds of the region. The brine shrimp feed on microscopic algae.
Alkali flies, Ephydra hians, live along the shores of the lake and walk underwater, encased in small air bubbles, for grazing and to lay eggs. These flies are an important source of food for migratory and nesting birds.
Eight nematode species were found living in the littoral sediment:
* Auanema spec., which is outstanding for its extreme arsenic resistance (survives concentrations 500 times higher than humans), having 3 sexes, and being viviparous.
* Pellioditis spec.
* Mononchoides americanus
* Diplogaster rivalis
* species of the family Mermithidae
* Prismatolaimus dolichurus
* 2 species of the order Monhysterida | 1 | Applied and Interdisciplinary Chemistry |
Nanoparticles have been explored as a delivery system for various drugs, such as improving the oral bioavailability of drugs with poor absorption characteristics. However, this has not proved successful with CoQ, although reports have differed widely. The use of aqueous suspension of finely powdered CoQ in pure water also reveals only a minor effect. | 1 | Applied and Interdisciplinary Chemistry |
For the deprotonation of acids, K is known as K, the acid dissociation constant. Strong acids, such as sulfuric or phosphoric acid, have large dissociation constants; weak acids, such as acetic acid, have small dissociation constants.
The symbol K, used for the acid dissociation constant, can lead to confusion with the association constant, and it may be necessary to see the reaction or the equilibrium expression to know which is meant.
Acid dissociation constants are sometimes expressed by pK, which is defined by
This notation is seen in other contexts as well; it is mainly used for covalent dissociations (i.e., reactions in which chemical bonds are made or broken) since such dissociation constants can vary greatly.
A molecule can have several acid dissociation constants. In this regard, that is depending on the number of the protons they can give up, we define monoprotic, diprotic and triprotic acids. The first (e.g., acetic acid or ammonium) have only one dissociable group, the second (e.g., carbonic acid, bicarbonate, glycine) have two dissociable groups and the third (e.g., phosphoric acid) have three dissociable groups. In the case of multiple pK values they are designated by indices: pK, pK, pK and so on. For amino acids, the pK constant refers to its carboxyl (–COOH) group, pK refers to its amino (–NH) group and the pK is the pK value of its side chain. | 0 | Theoretical and Fundamental Chemistry |
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