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SNPs have historically been used to match a forensic DNA sample to a suspect but has been made obsolete due to advancing STR-based DNA fingerprinting techniques. However, the development of next-generation-sequencing (NGS) technology may allow for more opportunities for the use of SNPs in phenotypic clues such as ethnicity, hair color, and eye color with a good probability of a match. This can additionally be applied to increase the accuracy of facial reconstructions by providing information that may otherwise be unknown, and this information can be used to help identify suspects even without a STR DNA profile match.
Some cons to using SNPs versus STRs is that SNPs yield less information than STRs, and therefore more SNPs are needed for analysis before a profile of a suspect is able to be created. Additionally, SNPs heavily rely on the presence of a database for comparative analysis of samples. However, in instances with degraded or small volume samples, SNP techniques are an excellent alternative to STR methods. SNPs (as opposed to STRs) have an abundance of potential markers, can be fully automated, and a possible reduction of required fragment length to less than 100bp.[26] | 1 | Biochemistry |
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 | Biochemistry |
Immobilized enzymes have important application uses as they reduce costs and improve the outcome of the reaction they catalyze. Advantages include:
;Convenience: Minuscule amounts of protein dissolve in the reaction, so workup can be much easier. Upon completion, reaction mixtures typically contain only solvent and reaction products.
;Economy: The immobilized enzyme is easily removed from the reaction making it easy to recycle the biocatalyst. This is particularly useful in processes such as the production of Lactose Free Milk, as the milk can be drained from a container leaving the enzyme (Lactase) inside ready for the next batch.
;Stability: Immobilized enzymes typically have greater thermal and operational stability than the soluble form of the enzyme.
In the past, biological washing powders and detergents contained many proteases and lipases that broke down dirt. However, when the cleaning products contacted human skin, they created allergic reactions. This is why immobilization of enzymes is important, for many application fields.
Immobilized enzymes are used in various applications including: food, chemical, pharmaceutical, and medical industry. In the food industry for example, Immobilized enzymes are used for the manufacturing of several types of zero-calorie sweetners, Allulose for instance is an epimer of fructose, which is different structurally, resulting in it not being absorbable by human bodies when ingested. Another example of immobilized-enzyme-based sweetners include: Tagatose (immobilized β-galactosidase).
In the chemical (cosmetics) industry as well, immobilized enzymes are used for the production of emollient esters by utilizing immobilized CalB enzyme. The first company to use such method is Evonik company in 2000. The enzyme Lipase-CalB in its immobilized state is actually used in other pharmaceutical applications for the production of Odanacatib, and Sofosbuvir. | 4 | Stereochemistry |
Supercritical fluids generally have properties between those of a gas and a liquid. In Table 1, the critical properties are shown for some substances that are commonly used as supercritical fluids.
Table 2 shows density, diffusivity and viscosity for typical liquids, gases and supercritical fluids.
Also, there is no surface tension in a supercritical fluid, as there is no liquid/gas phase boundary. By changing the pressure and temperature of the fluid, the properties can be "tuned" to be more liquid-like or more gas-like. One of the most important properties is the solubility of material in the fluid. Solubility in a supercritical fluid tends to increase with density of the fluid (at constant temperature). Since density increases with pressure, solubility tends to increase with pressure. The relationship with temperature is a little more complicated. At constant density, solubility will increase with temperature. However, close to the critical point, the density can drop sharply with a slight increase in temperature. Therefore, close to the critical temperature, solubility often drops with increasing temperature, then rises again. | 7 | Physical Chemistry |
In chemistry, a diradical is a molecular species with two electrons occupying molecular orbitals (MOs) which are degenerate. The term "diradical" is mainly used to describe organic compounds, where most diradicals are extremely reactive and in fact rarely isolated. Diradicals are even-electron molecules but have one fewer bond than the number permitted by the octet rule.
Examples of diradical species can also be found in coordination chemistry, for example among bis(1,2-dithiolene) metal complexes. | 0 | Organic Chemistry |
The model and its variants have a number of simplifying assumptions. Three of them are listing below.
#The organisms are modeled as gene regulatory networks. The models assume that gene expression is regulated exclusively at the transcriptional level;
#The product of a gene can regulate the expression of (be a regulator of) that source gene or other genes. The models assume that a gene can only produce one active transcriptional regulator;
#The effects of one regulator are independent of effects of other regulators on the same target gene. | 1 | Biochemistry |
The effects of enrichment can be most simply attained in a greenhouse (see for its agricultural use). However, for experimentation, the results obtained in a greenhouse would be doubted due to it introducing too many confounding variables. Open-air chambers have been similarly doubted, with some critiques attributing, e.g., a decline in mineral concentrations found in these -enrichment experiments to constraints put on the root system. The current state-of-the art is the FACE methodology, where is put out directly in the open field. Even then, there are doubts over whether the results of FACE in one part of the world applies to another. | 2 | Environmental Chemistry |
The internal states of each ion can be treated as a two level system, with eigenstates denoted and . One of the ion's normal modes is chosen to be the transfer mode used for state mapping. This motional mode must be shared by both ions, which requires both ions be similar in mass. The normal mode has harmonic oscillator states denoted as , where n is the nth level of mode m. The wave function
denotes both ions and the transfer mode in the ground state. S and L represent the spectroscopy and logic ion. The spectroscopy ion's spectroscopy transition is then excited with a laser, producing the state:
A red sideband pi-pulse is then driven on the spectroscopy ion, resulting in the state:
At this stage, the spectroscopy ions internal state has been mapped on to the transfer mode. The internal state of the ion has been coupled to its motional mode. The state is unaffected by the pulse of light carrying out this operation because the state does not exist. QLS takes advantage of this in order to map the spectroscopy ions state onto the transfer mode. A final red sideband pi-pulse is applied to the logic ion, resulting in the state:
The spectroscopy ion's initial state has been mapped onto the logic ion, which can then be detected. | 7 | Physical Chemistry |
The three types of photooxygenation reactions are distinguished by the mechanisms that they proceed through, as they are capable of yielding different or similar products depending on environmental conditions. Type I and II reactions proceed through neutral intermediates, while type III reactions proceed through charged species. The absence or presence of O is what distinguishes type I and type II reactions, respectively. | 5 | Photochemistry |
Klyne met Barbara Clayton in 1947 while both were employed at the Medical Research Council; they married in 1949. | 4 | Stereochemistry |
These reagents were discovered by Henry Gilman and coworkers. Lithium dimethylcopper (CH)CuLi can be prepared by adding copper(I) iodide to methyllithium in tetrahydrofuran at −78 °C. In the reaction depicted below, the Gilman reagent is a methylating reagent reacting with an alkyne in a conjugate addition, and the negative charge is trapped in a nucleophilic acyl substitution with the ester group forming a cyclic enone. | 0 | Organic Chemistry |
The genomic distribution of SNPs is not homogenous; SNPs occur in non-coding regions more frequently than in coding regions or, in general, where natural selection is acting and "fixing" the allele (eliminating other variants) of the SNP that constitutes the most favorable genetic adaptation. Other factors, like genetic recombination and mutation rate, can also determine SNP density.
SNP density can be predicted by the presence of microsatellites: AT microsatellites in particular are potent predictors of SNP density, with long (AT)(n) repeat tracts tending to be found in regions of significantly reduced SNP density and low GC content. | 1 | Biochemistry |
TMTTF as well as BEDT-TTF are based on the molecule TTF (tetrathiafulvalene). Using tetrathiapentalene (TTP) as basic molecules one receives a variety of new organic molecules serving as cations in organic crystals. Some of them are superconducting. This class of superconductors was only reported recently and investigations are still under process. | 0 | Organic Chemistry |
Exome sequencing is only able to identify those variants found in the coding region of genes which affect protein function. It is not able to identify the structural and non-coding variants associated with the disease, which can be found using other methods such as whole genome sequencing. There remains 99% of the human genome that is not covered using exome sequencing, and exome sequencing allows sequencing of portions of the genome over at least 20 times as many samples compared to whole genome sequencing. For translation of identified rare variants into the clinic, sample size and the ability to interpret the results to provide a clinical diagnosis indicates that with the current knowledge in genetics, there are reports of exome sequencing being used for assisting diagnosis. The cost of exome sequencing is typically lower than whole genome sequencing. | 1 | Biochemistry |
As real measurement signals contain a certain level of noise, the derived 2D spectra are influenced and degraded with substantial higher amounts of noise. Hence, interpretation begins with studying the autocorrelation spectrum on the main diagonal of the 2D synchronous spectrum. In the 2D synchronous main diagonal signal on the right 4 peaks are visible at 10, 20, 30, and 40 (see also the 4 corresponding positive autopeaks in the 2D synchronous spectrum on the right). This indicates that in the original dataset 4 peaks of changing intensity are present. The intensity of peaks on the autocorrelation spectrum are directly proportional to the relative importance of the intensity change in the original spectra. Hence, if an intense band is present at position x, it is very likely that a true intensity change is occurring and the peak is not due to noise.
Additional techniques help to filter the peaks that can be seen in the 2D synchronous and asynchronous spectra. | 7 | Physical Chemistry |
Hammond's postulate (or alternatively the Hammond–Leffler postulate), is a hypothesis in physical organic chemistry which describes the geometric structure of the transition state in an organic chemical reaction. First proposed by George Hammond in 1955, the postulate states that:
Therefore, the geometric structure of a state can be predicted by comparing its energy to the species neighboring it along the reaction coordinate. For example, in an exothermic reaction the transition state is closer in energy to the reactants than to the products. Therefore, the transition state will be more geometrically similar to the reactants than to the products. In contrast, however, in an endothermic reaction the transition state is closer in energy to the products than to the reactants. So, according to Hammond’s postulate the structure of the transition state would resemble the products more than the reactants. This type of comparison is especially useful because most transition states cannot be characterized experimentally.
Hammonds postulate also helps to explain and rationalize the Bell–Evans–Polanyi principle. Namely, this principle describes the experimental observation that the rate of a reaction, and therefore its activation energy, is affected by the enthalpy of that reaction. Hammonds postulate explains this observation by describing how varying the enthalpy of a reaction would also change the structure of the transition state. In turn, this change in geometric structure would alter the energy of the transition state, and therefore the activation energy and reaction rate as well.
The postulate has also been used to predict the shape of reaction coordinate diagrams. For example, electrophilic aromatic substitution involves a distinct intermediate and two less well defined states. By measuring the effects of aromatic substituents and applying Hammond's postulate it was concluded that the rate-determining step involves formation of a transition state that should resemble the intermediate complex. | 7 | Physical Chemistry |
Emanuel Gil-Av was born 1916 in Pensa of Tzarist Russia. After the death of his father, a physician, the family moved first to Central Europe and in 1928 to Tel-Aviv, Israel, where Gil-Av attended High School. Gil-Av studied petroleum chemistry at the University of Strasbourg. In 1940 he escaped the German occupation to England where he worked at first in the chemical laboratory of Chaim Weizmann, followed by the Petrochemical Ltd. in Manchester. After World War II, he moved to Palestine and he joined the Daniel Sieff Institute in Rehovot which was later on to become the Weizmann Institute of Science. In 1951 he earned his PhD under the supervision of Ernst David Bergmann.
In his study of oil shale deposits, Gil-Av developed complex-forming stationary phases employing silver(I) ions for selective olefin separations by gas chromatography (GC). In co-operation with the centre of peptide chemistry at the Weizmann Institute of Science, he developed methods of the gas-chromatographic resolution of racemic α-amino acids. By coating a glass capillary column with the chiral stationary phase (CSP) N-trifluoroacetyl-L-isoleucine lauryl ester, Gil-Av et al. carried out in 1966 the first gas-chromatographic enantioseparation of racemic amino acids as N-trifluoroacetyl-O-alkyl derivatives. Many racemic compounds, amenable for enantioselective interaction via hydrogen bonding with the CSP, could be analytically enantioseparated by GC.
Further contributions of Gil-Av and associates are concerned with the use of chiral mobile phase additives (CMPAs) in liquid chromatography (LC), enantiomeric separation of helicenes by supramolecular LC, the temperature-dependent reversal of enantioselectivity by enthalpy-entropy compensation and non-linear effects leading to enantiomeric enrichment during chromatography on achiral stationary phases. | 3 | Analytical Chemistry |
An intermolecular force (IMF) (or secondary force) is the force that mediates interaction between molecules, including the electromagnetic forces of attraction
or repulsion which act between atoms and other types of neighbouring particles, e.g. atoms or ions. Intermolecular forces are weak relative to intramolecular forces – the forces which hold a molecule together. For example, the covalent bond, involving sharing electron pairs between atoms, is much stronger than the forces present between neighboring molecules. Both sets of forces are essential parts of force fields frequently used in molecular mechanics.
The first reference to the nature of microscopic forces is found in Alexis Clairauts work Théorie de la figure de la Terre,' published in Paris in 1743. Other scientists who have contributed to the investigation of microscopic forces include: Laplace, Gauss, Maxwell, Boltzmann and Pauling.
Attractive intermolecular forces are categorized into the following types:
*Hydrogen bonding
*Ion–dipole forces and ion–induced dipole force
*Cation–π, σ–π and π–π bonding
*Van der Waals forces – Keesom force, Debye force, and London dispersion force
*Cation–cation bonding
*Salt bridge (protein and supramolecular)
Information on intermolecular forces is obtained by macroscopic measurements of properties like viscosity, pressure, volume, temperature (PVT) data. The link to microscopic aspects is given by virial coefficients and intermolecular pair potentials, such as the Mie potential, Buckingham potential or Lennard-Jones potential.
In the broadest sense, it can be understood as such interactions between any particles (molecules, atoms, ions and molecular ions) in which the formation of chemical, that is, ionic, covalent or metallic bonds does not occur. In other words, these interactions are significantly weaker than covalent ones and do not lead to a significant restructuring of the electronic structure of the interacting particles. (This is only partially true. For example, all enzymatic and catalytic reactions begin with a weak intermolecular interaction between a substrate and an enzyme or a molecule with a catalyst, but several such weak interactions with the required spatial configuration of the active center of the enzyme lead to significant restructuring changes the energy state of molecules or substrate, which ultimately leads to the breaking of some and the formation of other covalent chemical bonds. Strictly speaking, all enzymatic reactions begin with intermolecular interactions between the substrate and the enzyme, therefore the importance of these interactions is especially great in biochemistry and molecular biology, and is the basis of enzymology). | 6 | Supramolecular Chemistry |
In E. coli, TMAO reductase is encoded by the torCAD operon. The torC gene encodes a pentahemic c-type cytochrome (TorC). TorC is likely to transfer electrons directly to the periplasmic TorA terminal enzyme encoded by the torA gene. The anaerobic expression of the torCAD operon is strictly controlled by the presence of TMAO or related compounds.
There are several different metabolic pathways that involve TMAO and TMA. The reduction of TMAO to TMA, catalyzed by TMAO reductase, as part of the electron transport chain follows the following reaction:
NADH + H + trimethylamine N-oxide NAD + trimethylamine + HO
However, both the R. denitrificans and E. coli enzymes can accept electrons from cytochromes:
:trimethylamine + 2 (ferricytochrome c)-subunit + HO → trimethylamine N-oxide + 2 (ferrocytochrome c)-subunit + 2 H
Other reactions involving TMAO and TMA include:
* The oxidation of TMA to TMAO, which occurs in some methylotrophs as an initial step in utilizing TMA as a source of carbon
* The demethylation of TMAO to dimethylamine and formaldehyde by methylotrophs
* The oxidative demethylation of TMA to dimethylamine and formaldehyde by methylotrophs
* The production of methane from TMA and other methylamines by some methanogens | 1 | Biochemistry |
AMGs play a crucial role in microbial adaptation to environmental changes. In extreme environments, AMGs can encode for alternate energy pathways such as subunits of dissimilatory sulfite reductase. The ability of viruses to confer new metabolic traits to their hosts enhances the resilience of microbial communities facing shifts in temperature, nutrient availability, or other environmental stressors. AMGs can also serve as a genetic pool in shaping the evolution of their hosts. | 1 | Biochemistry |
Several properties may make Glycoazodyes an environmentally friendly alternative to traditional synthetic dyes. The increased hydrophilicity of Glycoazodyes allows for the elimination of surfactants, mordants, and salts, during the dyeing process and permits the aqueous dying of a variety of textiles at moderate temperatures and pressures. The unique structure may also allow for the treatment of textile effluent through biological means. Fusarium oxysporum efficiently decolourizes the first-generation Glycoazodye 4-{N,N-Bis[2-(D-galactopyranos-6-yloxy)ethyl]-amino}azobenzene. Various other Ascomycota fungi show a similar potential to decolourise Glycoazodyes, but to a lesser extent. Detoxification has been measured, using the Daphnia magna acute toxicity test, showing a 92% dye detoxification after 6 days. This detoxification method produces low concentrations of nitrobenzene, aniline, and nitrosobenzene. | 0 | Organic Chemistry |
Radioactive water baths have been applied since 1906 in Jáchymov, Czech Republic, but even before radon discovery they were used in Bad Gastein, Austria. Radium-rich springs are also used in traditional Japanese onsen in Misasa, Tottori Prefecture. Drinking therapy is applied in Bad Brambach, Germany. Inhalation therapy is carried out in Gasteiner-Heilstollen, Austria, in Kowary, Poland and in Boulder, Montana, United States. In the United States and Europe there are several "radon spas", where people sit for minutes or hours in a high-radon atmosphere in the belief that low doses of radiation will invigorate or energize them. | 2 | Environmental Chemistry |
Copperas works are manufactories where copperas (iron(II) sulfate) is produced from pyrite, often obtained as a byproduct during coal mining, and iron. The history of producing green vitriol, as it was known, goes back hundreds of years in Scotland. In 1814 the wool-producing city of Steubenville, Ohio had seven copperas-producing manufacturers.
Pyrite has been used since classical times to manufacture copperas. Iron pyrite was heaped up and allowed to weather (an example of an early form of heap leaching). The acidic runoff from the heap was then boiled with iron to produce iron sulfate.
Containment of leachate is important due to its toxicity; a fish kill that occurred in the 1890s in the Kanawha River was attributed to copperas solution release from the mines in Cannelton, West Virginia.
The "vitriolic waters of Fahlun" (Falun, Sweden), according to Murray (1844), annually produced "about 600 quintals of green vitriol" (sulfate of iron), as well as a "small quantity of blue vitriol" (sulfate of copper). These may have been obtained through evaporation of the groundwater associated with mines in order to yield the crystalline form of copperas. | 8 | Metallurgy |
A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules. These "fingerprints" can be compared to the previously collected ones of atoms and molecules, and are thus used to identify the atomic and molecular components of stars and planets, which would otherwise be impossible. | 7 | Physical Chemistry |
Metallacrown nomenclature has been developed to mimic the nomenclature of crown ethers, which are named by the total number of atoms in the ring, followed by "C" for "crown," and the number of oxygen atoms in the ring. For example, 12-crown-4 or 12-C-4 describes Figure 2a. When naming metallacrowns, a similar format is followed. However, the C becomes "MC" for "metallacrown" and the "MC" is followed by the ring metal, other heteroatom, and the ligand used to make the metallacrown. For example, metallacrown b in the figure above is named [12-MC-4], where "shi" is the ligand, salicylhydroxamic acid. | 6 | Supramolecular Chemistry |
The Imd pathway bears a number of similarities to mammalian TNFR signalling, though many of the intracellular regulatory proteins of Imd signalling also bear homology to different signalling cascades of human Toll-like receptors. | 1 | Biochemistry |
Lichen identification uses growth form, microscopy and reactions to chemical tests.
The outcome of the "Pd test" is called "Pd", which is also used as an abbreviation for the chemical used in the test, para-phenylenediamine. If putting a drop on a lichen turns an area bright yellow to orange, this helps identify it as belonging to either the genus Cladonia or Lecanora. | 2 | Environmental Chemistry |
Amperometric titration refers to a class of titrations in which the equivalence point is determined through measurement of the electric current produced by the titration reaction. It is a form of quantitative analysis. | 3 | Analytical Chemistry |
More generally, stereographic projection may be applied to the unit -sphere in ()-dimensional Euclidean space . If is a point of and a hyperplane in , then the stereographic projection of a point is the point of intersection of the line with . In Cartesian coordinates (, from 0 to ) on and (, from 1 to n) on , the projection from is given by
Defining
the inverse is given by
Still more generally, suppose that is a (nonsingular) quadric hypersurface in the projective space . In other words, is the locus of zeros of a non-singular quadratic form in the homogeneous coordinates . Fix any point on and a hyperplane in not containing . Then the stereographic projection of a point in is the unique point of intersection of with . As before, the stereographic projection is conformal and invertible on a non-empty Zariski open set. The stereographic projection presents the quadric hypersurface as a rational hypersurface. This construction plays a role in algebraic geometry and conformal geometry. | 3 | Analytical Chemistry |
Mitochondrial disease can manifest in many different ways whether in children or adults. Examples of mitochondrial diseases include:
* Mitochondrial myopathy
* Maternally inherited diabetes mellitus and deafness (MIDD)
** While diabetes mellitus and deafness can be found together for other reasons, at an early age this combination can be due to mitochondrial disease, as may occur in Kearns–Sayre syndrome and Pearson syndrome
* Leber's hereditary optic neuropathy (LHON)
**LHON is an eye disorder characterized by progressive loss of central vision due to degeneration of the optic nerves and retina (apparently affecting between 1 in 30,000 and 1 in 50,000 people); visual loss typically begins in young adulthood
* Leigh syndrome, subacute necrotizing encephalomyelopathy
** after normal development the disease usually begins late in the first year of life, although onset may occur in adulthood
** a rapid decline in function occurs and is marked by seizures, altered states of consciousness, dementia, ventilatory failure
* Neuropathy, ataxia, retinitis pigmentosa, and ptosis (NARP)
** progressive symptoms as described in the acronym
** dementia
* Myoneurogenic gastrointestinal encephalopathy (MNGIE)
** gastrointestinal pseudo-obstruction
** neuropathy
* MERRF syndrome
** progressive myoclonic epilepsy
** "Ragged Red Fibers" are clumps of diseased mitochondria that accumulate in the subsarcolemmal region of the muscle fiber and appear when muscle is stained with modified Gömöri trichrome stain
** short stature
** hearing loss
** lactic acidosis
** exercise intolerance
* MELAS syndrome, mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes
* Mitochondrial DNA depletion syndrome
Conditions such as Friedreichs ataxia can affect the mitochondria but are not associated with mitochondrial proteins.' | 1 | Biochemistry |
The property of photoconversion in Kaede is contributed by the tripeptide, His-Tyr-Gly, that acts as a green chromophore that can be converted to red. Once Kaede is synthesized, a chromophore, 4-(p-hydroxybenzylidene)-5-imidazolinone, derived from the tripeptide mediates green fluorescence in Kaede. When exposed to UV, Kaede protein undergoes unconventional cleavage between the amide nitrogen and the α carbon (Cα) at His62 via a formal β-elimination reaction. Followed by the formation of a double bond between His62-Cα and –Cβ, the π-conjugation is extended to the imidazole ring of His62. A new chromophore, 2-[(1E)-2-(5-imidazolyl)ethenyl]-4-(p-hydroxybenzylidene)-5-imidazolinone, is formed with the red-emitting property.
The cleavage of the tripeptide was analysed by SDS-PAGE analysis. Unconverted green Kaede shows one band at 28 kDa, whereas two bands at 18 kDa and 10 kDa are observed for converted red Kaede, indicating that the cleavage is crucial for the photoconversion.
A shifting of the absorption and emission spectrum in Kaede is caused by the cleavage of the tripeptide. Before the photoconversion, Kaede displays a major absorption wavelength maximum at 508 nm, accompanied with a slight shoulder at 475 nm. When it is excited at 480 nm, green fluorescence is emitted with a peak of 518 nm.
When Kaede is irradiated with UV or violet light, the major absorption peak shifts to 572 nm. When excited at 540 nm, Kaede showed an emission maximum at 582 nm with a shoulder at 627 nm and the 518-nm peak. Red fluorescence is emitted after this photoconversion.
The photoconversion in Kaede is irreversible. Exposure in dark or illumination at 570 nm cannot restore its original green fluorescence. A reduced fluorescence is observed in red, photoconverted Kaede when it is intensively exposed to 405 nm light, followed by partial recover after several minutes. | 1 | Biochemistry |
All sulfate-reducing organisms are strict anaerobes. Because sulfate is energetically stable, before it can be metabolized it must first be activated by adenylation to form APS (adenosine 5’-phosphosulfate) thereby consuming ATP. The APS is then reduced by the enzyme APS reductase to form sulfite () and AMP. In organisms that use carbon compounds as electron donors, the ATP consumed is accounted for by fermentation of the carbon substrate. The hydrogen produced during fermentation is actually what drives respiration during sulfate reduction. | 1 | Biochemistry |
The material used is said to be an organic and non-toxic blend of baking powder, yeast, and other ingredients. Deriving its name from the animal of the same name which is known for its ability to spray a foul-smelling fluid, "Skunk" is dispersed as a form of yellow mist, fired from a water cannon, which leaves a powerful odor similar to rot or sewage on whatever it touches. Skunk is also sold in handheld canisters and in grenades which can be thrown or fired as projectiles (see riot gun). The company later marketed Skunk to law enforcement agencies worldwide, specifically American local police departments. Several US police departments, including the St. Louis Metropolitan Police Department, purchased it.
A BBC reporter describes its effects as follows:
A reporter for Reuters described its effect in the following words:
However, when tested in India, the product failed miserably:
In December 2017, Haaretz reported:
Some report that the smell is so potent it can linger on clothes for months, if not years. | 1 | Biochemistry |
Modulating the pyrimidine metabolism pharmacologically has therapeutical uses, and could implement in cancer treatment.
Pyrimidine synthesis inhibitors are used in active moderate to severe rheumatoid arthritis and psoriatic arthritis, as well as in multiple sclerosis. Examples include Leflunomide and Teriflunomide (the active metabolite of leflunomide). | 1 | Biochemistry |
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). | 7 | Physical Chemistry |
The Blueprint Initiative started as a research program in the lab of Dr. Christopher Hogue at the Samuel Lunenfeld Research Institute at Mount Sinai Hospital in Toronto. On December 14, 2005, Unleashed Informatics Limited acquired the commercial rights to The Blueprint Initiative intellectual property. This included rights to the protein interaction database BIND, the small molecule interaction database SMID, as well as the data warehouse SeqHound. Unleashed Informatics is a data management service provider and is overseeing the management and curation of The Blueprint Initiative under the guidance of Dr. Hogue. | 1 | Biochemistry |
Full spectral imaging, along with empirical reflectance retrieval and autonomous remote sensing are the components of the new systems for remote sensing and the successor to the Landsat series of satellites of the Landsat program. | 7 | Physical Chemistry |
Moisture is an important property of coal, as all coals are mined wet. Groundwater and other extraneous moisture is known as adventitious moisture and is readily evaporated. Moisture held within the coal itself is known as inherent moisture and is analysed quantitatively. Moisture may occur in four possible forms within coal:
* Surface moisture: water held on the surface of coal particles or macerals
* Hygroscopic moisture: water held by capillary action within the microfractures of the coal
* Decomposition moisture: water held within the coal's decomposed organic compounds
* Mineral moisture: water which comprises part of the crystal structure of hydrous silicates such as clays
Total moisture is analysed by loss of mass between an untreated sample and the sample once analysed. This is achieved by any of the following methods;
# Heating the coal with toluene
# Drying in a minimum free-space oven at within a nitrogen atmosphere
# Drying in air at and relative loss of mass determined
Methods 1 and 2 are suitable with low-rank coals, but method 3 is only suitable for high-rank coals as free air drying low-rank coals may promote oxidation.
Inherent moisture is analysed similarly, though it may be done in a vacuum. | 3 | Analytical Chemistry |
The resonance assisted hydrogen bond (commonly abbreviated as RAHB) is a strong type of hydrogen bond. It is characterized by the π-delocalization that involves the hydrogen and cannot be properly described by the electrostatic model alone. This description of the hydrogen bond has been proposed to describe unusually short distances generally observed between or . | 6 | Supramolecular Chemistry |
Born in Thames on 14 July 1935, Phillips was educated at Westport Technical College and Christchurch Boys' High School. He studied at Canterbury University College, from where he graduated with an MSc with first-class honours in 1958. After a PhD at the University of Cambridge and post-doctoral research at McGill University, he returned to lecture at Canterbury, rising to the rank of professor in 1966.
In 1968, Phillips was elected a Fellow of the Royal Society of New Zealand, and in 1979 he won the society's Hector Medal.
In 1959, Phillips married Pamela Anne Johnstone, and the couple went on to have two children. He died in Christchurch on 24 September 2023, at the age of 88. | 7 | Physical Chemistry |
Carotenoderma, also referred to as carotenemia, is a benign and reversible medical condition where an excess of dietary carotenoids results in orange discoloration of the outermost skin layer. It is associated with a high blood β-carotene value. This can occur after a month or two of consumption of beta-carotene rich foods, such as carrots, carrot juice, tangerine juice, mangos, or in Africa, red palm oil. β-carotene dietary supplements can have the same effect. The discoloration extends to palms and soles of feet, but not to the white of the eye, which helps distinguish the condition from jaundice. Consumption of greater than 30 mg/day for a prolonged period has been confirmed as leading to carotenemia. | 1 | Biochemistry |
When a crystal of a binary oxide is cleaved to generate two new surfaces, each solid's charge remains neutral. However, the structure of the two newly created surfaces may or may not be the same. If the structures are identical, the surface will be dipoleless and is considered a nonpolar surface. If the structures are different, the surface will have a strong dipole and is considered a polar surface. Examples of nonpolar surfaces include the rocksalt (100) surface, the rutile (100), (110) and (001) surfaces and the pervoskite (100) surface. An example of a polar surface is the rocksalt (111) surface. In general, a polar surface is less stable than a nonpolar surface because a dipole moment increases the surface Gibbs energy. Also, oxygen polar surfaces are more stable than metal polar surfaces because oxygen ions are more polarizable, which lowers the surface energy. | 7 | Physical Chemistry |
An approach published in 2007 like Corey's starts by an asymmetric Diels-Alder reaction this time with starting materials pyridine and acrolein.
Pyridine (1) is reduced with sodium borohydride in presence of benzyl chloroformate to the Cbz protected dihydropyridine 2. The asymmetric Diels-Alder reaction with acrolein 3 is carried out with the McMillan catalyst to the aldehyde 4 as the endo isomer which is oxidized to the carboxylic acid 5 with sodium chlorite, monopotassium phosphate and 2-methyl-2-butene. Addition of bromine gives halolactonization product 6 and after replacement of the Cbz protective group by a BOC protective group in 7 (hydrogenolysis in the presence of di-tert-butyl dicarbonate) a carbonyl group is introduced in intermediate 8 by catalytic ruthenium(IV) oxide and sacrificial catalyst sodium periodate. Addition of ammonia cleaves the ester group to form amide 9 the alcohol group of which is mesylated to compound 10. In the next step iodobenzene diacetate is added, converting the amide in a Hofmann rearrangement to the allyl carbamate 12 after capturing the intermediate isocyanate with allyl alcohol 11. On addition of sodium ethoxide in ethanol three reactions take place simultaneously: cleavage of the amide to form new an ethyl ester group, displacement of the mesyl group by newly formed BOC protected amine to an aziridine group and an elimination reaction forming the alkene group in 13 with liberation of HBr. In the final two steps the aziridine ring is opened by 3-pentanol 14 and boron trifluoride to aminoether 15 with the BOC group replaced by an acyl group and on removal of the other amine protecting group (Pd/C, PhP, and 1,3-dimethylbarbituric acid in ethanol) and addition of phosphoric acid oseltamivir 16 is obtained. | 0 | Organic Chemistry |
The modern optical mapping platform works as follows:
#Genomic DNA is obtained from lysed cells, and randomly sheared to produce a "library" of large genomic molecules for optical mapping.
#A single molecule of DNA is stretched (or elongated) and held in place on a slide under a fluorescent microscope due to charge interactions.
#The DNA molecule is digested by added restriction enzymes, which cleave at specific digestion sites. The resulting molecule fragments remain attached to the surface. The fragment ends at the cleavage sites are drawn back (due to elasticity of linearized DNA), leaving gaps which are identifiable under the microscope.
#DNA fragments stained with intercalating dye are visualized by fluorescence microscopy and are sized by measuring the integrated fluorescence intensity. This produces an optical map of single molecules.
#Individual optical maps are combined to produce a consensus, genomic optical map. | 1 | Biochemistry |
Disease gene identification is a process by which scientists identify the mutant genotypes responsible for an inherited genetic disorder. Mutations in these genes can include single nucleotide substitutions, single nucleotide additions/deletions, deletion of the entire gene, and other genetic abnormalities. | 1 | Biochemistry |
The Jameson Cell can be used for the reverse flotation of silica from iron ore, where flotation columns have traditionally been used. | 8 | Metallurgy |
Mutations in super-enhancers have been noted in various diseases, including cancers, type 1 diabetes, Alzheimer’s disease, lupus, rheumatoid arthritis, multiple sclerosis, systemic scleroderma, primary biliary cirrhosis, Crohn’s disease, Graves disease, vitiligo, and atrial fibrillation. A similar enrichment in disease-associated sequence variation has also been observed for stretch enhancers.
Super-enhancers may play important roles in the misregulation of gene expression in cancer. During tumor development, tumor cells acquire super-enhancers at key oncogenes, which drive higher levels of transcription of these genes than in healthy cells. Altered super-enhancer function is also induced by mutations of chromatin regulators. Acquired super-enhancers may thus be biomarkers that could be useful for diagnosis and therapeutic intervention.
Proteins enriched at super-enhancers include the targets of small molecules that target transcription-regulating proteins and have been deployed against cancers. For instance, super-enhancers rely on exceptional amounts of CDK7, and, in cancer, multiple papers report the loss of expression of their target genes when cells are treated with the CDK7 inhibitor THZ1. Similarly, super-enhancers are enriched in the target of the JQ1 small molecule, BRD4, so treatment with JQ1 causes exceptional losses in expression for super-enhancer—associated genes. | 1 | Biochemistry |
Photosynthetically active radiation (PAR) designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more or less with the range of light visible to the human eye. Photons at shorter wavelengths tend to be so energetic that they can be damaging to cells and tissues, but are mostly filtered out by the ozone layer in the stratosphere. Photons at longer wavelengths do not carry enough energy to allow photosynthesis to take place.
Other living organisms, such as cyanobacteria, purple bacteria, and heliobacteria, can exploit solar light in slightly extended spectral regions, such as the near-infrared. These bacteria live in environments such as the bottom of stagnant ponds, sediment and ocean depths. Because of their pigments, they form colorful mats of green, red and purple.
Chlorophyll, the most abundant plant pigment, is most efficient in capturing red and blue light. Accessory pigments such as carotenes and xanthophylls harvest some green light and pass it on to the photosynthetic process, but enough of the green wavelengths are reflected to give leaves their characteristic color. An exception to the predominance of chlorophyll is autumn, when chlorophyll is degraded (because it contains N and Mg) but the accessory pigments are not (because they only contain C, H and O) and remain in the leaf producing red, yellow and orange leaves.
In land plants, leaves absorb mostly red and blue light in the first layer of photosynthetic cells because of chlorophyll absorbance. Green light, however, penetrates deeper into the leaf interior and can drive photosynthesis more efficiently than red light. Because green and yellow wavelengths can transmit through chlorophyll and the entire leaf itself, they play a crucial role in growth beneath the plant canopy.
PAR measurement is used in agriculture, forestry and oceanography. One of the requirements for productive farmland is adequate PAR, so PAR is used to evaluate agricultural investment potential. PAR sensors stationed at various levels of the forest canopy measure the pattern of PAR availability and utilization. Photosynthetic rate and related parameters can be measured non-destructively using a photosynthesis system, and these instruments measure PAR and sometimes control PAR at set intensities. PAR measurements are also used to calculate the euphotic depth in the ocean.
In these contexts, the reason PAR is preferred over other lighting metrics such as luminous flux and illuminance is that these measures are based on human perception of brightness, which is strongly green biased and does not accurately describe the quantity of light usable for photosynthesis. | 5 | Photochemistry |
All chromatographic purifications and separations which are executed via solvent gradient batch chromatography can be performed using MCSGP. Typical examples are reversed phase purification of peptides, hydrophobic interaction chromatography for fatty acids or for example ion exchange chromatography of proteins or antibodies. The process can effectively enrich components, which have been fed in only small amounts. Continuous capturing of antibodies without affinity chromatography can be realized with the MCSGP-process. | 3 | Analytical Chemistry |
This piece is the larger part of the fragment broken during Bahadur Shah's reign. Henry Cousens (1902–03) measured its length as . Klaus Roessler (1995) found it to be long. It has a square cross-section. Roessler estimated its weight at .
In 1598, the Mughal emperor Akbars visit to Dhar was recorded on the pillar in form of a Persian language inscription. This piece also has some names and letters in Devanagari script. The names end in word Soni' ("goldsmith"), and seem to have been engraved while the original pillar was still intact. There are some other symbols and Persian characters scratched on the surface.
The autobiography of Akbars son Jahangir mentions that he saw this piece lying on ground in Dhar. He ordered it to be taken to Agra, intending to use it as a lamp post in the courtyard of Akbars tomb. It appears that Jahangir's orders were never carried out.
Until 1980, this piece lay in a sloping position against a masonry terrace. The local kids used it as a slide, because of which a large part of its surface gained a polished appearance. | 8 | Metallurgy |
Anodizing is one of the more environmentally friendly metal finishing processes. Except for organic (aka integral colour) anodizing, the by-products contain only small amounts of heavy metals, halogens, or volatile organic compounds. Integral color anodizing produces no VOCs, heavy metals, or halogens as all of the byproducts found in the effluent streams of other processes come from their dyes or plating materials. The most common anodizing effluents, aluminium hydroxide and aluminium sulfate, are recycled for the manufacturing of alum, baking powder, cosmetics, newsprint and fertilizer or used by industrial wastewater treatment systems. | 8 | Metallurgy |
Persephin is a neurotrophic factor in the glial cell line-derived neurotrophic factor (GDNF) family. Persephin shares around a 40% similarity in amino acid sequence compared to GDNF and neurturin, two members of the GDNF family. | 1 | Biochemistry |
The effectiveness of a dispersant may be analyzed with the following equations. The Area refers to the area under the absorbance/wavelength curve, which is determined using the trapezoidal rule. The absorbances are measured at 340, 370, and 400 nm.
Area = 30(Abs + Abs)/2 + 30(Abs + Abs)/2 (1)
The dispersant effectiveness may then be calculated using the equation below.
Effectiveness (%) = Total oil dispersed x 100/(ρV)
* ρ = density of the test oil (g/L)
* V = volume of oil added to test flask (L)
* Total oil dispersed = mass of oil x 120mL/30mL
* Mass of oil = concentration oil x V
* V = final volume of DCM-extract of water sample (0.020 L)
* Concentration of oil = area determined by Equation (1) / slope of calibration curve | 2 | Environmental Chemistry |
Retroviruses are established pathogens of veterinary importance. They are generally a cause of cancer or immune deficiency. | 1 | Biochemistry |
The copper-bronze metallurgy in the Harappan civilization was widespread and had a high variety and quality. The early use of iron may have developed from the practice of copper-smelting. While there is to date no proven evidence for smelted iron in the Indus Valley civilization, iron ore and iron items have been unearthed in eight Indus Valley sites, some of them dating to before 2600 BCE. There remains the possibility that some of these items were made of smelted iron, and the term "kṛṣṇa-ayas" might possibly also refer to these iron items, even if they are not made of smelted iron.
Lothali copper is unusually pure, lacking the arsenic typically used by coppersmiths across the rest of the Indus valley. Workers mixed tin with copper for the manufacture of celts, arrowheads, fishhooks, chisels, bangles, rings, drills and spearheads, although weapon manufacturing was minor. They also employed advanced metallurgy in following the cire perdue technique of casting, and used more than one-piece moulds for casting birds and animals. They also invented new tools such as curved saws and twisted drills unknown to other civilizations at the time. | 8 | Metallurgy |
The thermal decomposition of nitrate esters mainly yields the gases molecular nitrogen (N) and carbon dioxide. The considerable chemical energy of the detonation is due to the high strength of the bond in molecular nitrogen. This stoichiometry is illustrated by the equation for the detonation of nitroglycerin.
Illustrative of the highly sensitive nature of some organic nitrates is Si(CHONO). A single crystal of this compound detonates even upon contact with a teflon spatula and in fact made full characterization impossible. Another contributor to its exothermic decomposition (inferred from much safer in silico experimentation) is the ability of silicon in its crystal phase to coordinate to two oxygen nitrito groups in addition to regular coordination to the four carbon atoms. This additional coordination would make formation of silicon dioxide (one of the decomposition products) more facile. | 0 | Organic Chemistry |
Over the course of Earth's geologic history concentrations have played a role in biological evolution. The first photosynthetic organisms probably evolved early in the evolutionary history of life and most likely used reducing agents such as hydrogen or hydrogen sulfide as sources of electrons, rather than water. Cyanobacteria appeared later, and the excess oxygen they produced contributed to the oxygen catastrophe, which rendered the evolution of complex life possible. In recent geologic times, low concentrations below 600 parts per million might have been the stimulus that favored the evolution of C4 carbon fixation| plants which increased greatly in abundance between 7 and 5 million years ago over plants that use the less efficient C3 carbon fixation| metabolic pathway. At current atmospheric pressures photosynthesis shuts down when atmospheric concentrations fall below 150 ppm and 200 ppm although some microbes can extract carbon from the air at much lower concentrations. | 2 | Environmental Chemistry |
Robert Burns Woodward (April 10, 1917 – July 8, 1979) was an American organic chemist. He is considered by many to be the preeminent synthetic organic chemist of the twentieth century, having made many key contributions to the subject, especially in the synthesis of complex natural products and the determination of their molecular structure. He worked closely with Roald Hoffmann on theoretical studies of chemical reactions. He was awarded the Nobel Prize in Chemistry in 1965. | 4 | Stereochemistry |
Once inside the mitochondria, each cycle of β-oxidation, liberating a two carbon unit (acetyl-CoA), occurs in a sequence of four reactions:
This process continues until the entire chain is cleaved into acetyl CoA units. The final cycle produces two separate acetyl CoAs, instead of one acyl CoA and one acetyl CoA. For every cycle, the Acyl CoA unit is shortened by two carbon atoms. Concomitantly, one molecule of FADH, NADH and acetyl CoA are formed. | 1 | Biochemistry |
Subcooling may also be produced by superheating the gas leaving the evaporator and heading to the gas compressor. These systems withdraw heat from the liquid line and heat up the gas compressor's suction line. This is a very common solution to insure that gas reaches the compressor and liquid reaches the valve. It also allows maximum heat exchanger use as minimizes the portion of the heat exchangers used to change the temperature of the fluid, and maximizes the volume in which the refrigerant changes its phase (phenomena involving much more heat flow, the base principle of vapor-compression refrigeration).
An internal heat exchanger is simply a heat exchanger that uses the cold gas leaving the evaporator coil to cool the high-pressure liquid that is headed into the beginning of the evaporator coil via an expansion device. The gas is used to chill a chamber that normally has a series of pipes for the liquid running through it. The superheated gas then proceeds on to the compressor. The subcooling term refers to cooling the liquid below its boiling point. of subcooling means it is 10 °F colder than boiling at a given pressure. As it represents a difference of temperatures, the subcooling value is not measured on an absolute temperature scale, only on a relative scale as a temperature difference. | 7 | Physical Chemistry |
The first commercial production of MSA, developed in the 1940s by Standard Oil of Indiana, was based on oxidation of dimethylsulfide by from air. Although inexpensive, this process suffered from a poor product quality and explosion hazards.
In 1967, the Pennwalt Corporation (USA) developed a different process for dimethylsulfide (as a water-based emulsion) oxidation using chlorine, followed by extraction-purification. In 2022 this chlorine-oxidation process was used only by Arkema (France) for making high-purity MSA. This process is not popular on a large scale, because it co-produces large quantities of hydrochloric acid.
Between years 1970 and 2000 MSA was used only on a relatively small-scale in niche markets (for example, in the microelectronic and electroplating industries since the 1980s), which was mainly due to its rather high price and limited availability. However, this situation changed around 2003, when BASF launched commercial production of MSA in Ludwigshafen based on a modified version of the aforementioned air oxidation process, oxidising dimethyldisulfide with nitric acid which is then restored using atmospheric oxygen. The former is produced in one step from methanol from syngas, hydrogen and sulfur.
An even better (lower-cost and environmentally friendlier) process of making methanesulfonic acid was developed in 2016 by Grillo-Werke AG (Germany). It is based on a direct reaction between methane and oleum at around 50 °C and 100 bar in the presence of a potassium persulfate initiator. This technology was acquired and commercialized by BASF in 2019. | 0 | Organic Chemistry |
One class of example is the iodine clock reactions, in which an iodine species is mixed with redox reagents in the presence of starch. After a delay, a dark blue color suddenly appears due to the formation of a triiodide-starch complex.
Additional reagents can be added to some chemical clocks to build a chemical oscillator. For example, the Briggs–Rauscher reaction is derived from an iodine clock reaction by adding perchloric acid, malonic acid and manganese sulfate. | 7 | Physical Chemistry |
*DNA extraction
*Phenol–chloroform extraction
*Minicolumn purification
*RNA extraction
*Boom method
*Synchronous coefficient of drag alteration (SCODA) DNA purification | 1 | Biochemistry |
Most metal ores contain metals of interest (e.g. gold, copper, nickel) in some oxidized states and thus the goal of most metallurgical operations is to chemically reduce them to their pure metallic form. The question is how to convert highly impure metal ores into purified bulk metals. A vast array of operations have been developed to accomplish those tasks, one of which is electrowinning. In an ideal case, ore is extracted into a solution which is then subjected to electrolysis. The metal is deposited on the cathode. In a practical sense, this idealized process is complicated by some or all of the following considerations: the metal content is low (a few percent is typical), other metals deposit competitively with the desired one, the ore is not easily or efficiently dissolved. For these reasons, electrowinning is usually only used on purified solutions of a desired metal, e.g. cyanide-extracts of gold ores.
Because metal deposition rates are related to available surface area, maintaining properly working cathodes is important. Two cathode types exist, flat-plate and reticulated cathodes, each with its own advantages and disadvantages. Flat-plate cathodes can be cleaned and reused, and plated metals recovered by either mechanically scraping the cathode (or, the electrolyzed metal has a lower melting point than the cathode, heating the cathode to the electrolyzed metals melting point causing the electrolyzed metal to liquify and separate from the cathode, which remains solid). Reticulated cathodes have a much higher deposition rate compared to flat-plate cathodes due to their greater surface area. However, reticulated cathodes are not reusable and must' be sent off for recycling. Alternatively, starter cathodes of pre-refined metals can be used, which become an integral part of the finished metal ready for rolling or further processing. | 8 | Metallurgy |
In molecular genetics, a regulon is a group of genes that are regulated as a unit, generally controlled by the same regulatory gene that expresses a protein acting as a repressor or activator. This terminology is generally, although not exclusively, used in reference to prokaryotes, whose genomes are often organized into operons; the genes contained within a regulon are usually organized into more than one operon at disparate locations on the chromosome. Applied to eukaryotes, the term refers to any group of non-contiguous genes controlled by the same regulatory gene.
A modulon is a set of regulons or operons that are collectively regulated in response to changes in overall conditions or stresses, but may be under the control of different or overlapping regulatory molecules. The term stimulon is sometimes used to refer to the set of genes whose expression responds to specific environmental stimuli. | 1 | Biochemistry |
The Shannon entropy,
is the number of bits which would have to be transmitted to identify from equally likely possibilities, less the relative entropy of the uniform distribution on the random variates of , , from the true distribution — i.e. less the expected number of bits saved, which would have had to be sent if the value of were coded according to the uniform distribution rather than the true distribution . This definition of Shannon entropy forms the basis of E.T. Jaynes's alternative generalization to continuous distributions, the limiting density of discrete points (as opposed to the usual differential entropy), which defines the continuous entropy as
which is equivalent to: | 7 | Physical Chemistry |
Durrant has proposed an alternative definition of hypervalency, based on the analysis of atomic charge maps obtained from atoms in molecules theory. This approach defines a parameter called the valence electron equivalent, γ, as “the formal shared electron count at a given atom, obtained by any combination of valid ionic and covalent resonance forms that reproduces the observed charge distribution”. For any particular atom X, if the value of γ(X) is greater than 8, that atom is hypervalent. Using this alternative definition, many species such as PCl, , and XeF, that are hypervalent by Musher's definition, are reclassified as hypercoordinate but not hypervalent, due to strongly ionic bonding that draws electrons away from the central atom. On the other hand, some compounds that are normally written with ionic bonds in order to conform to the octet rule, such as ozone O, nitrous oxide NNO, and trimethylamine N-oxide , are found to be genuinely hypervalent. Examples of γ calculations for phosphate (γ(P) = 2.6, non-hypervalent) and orthonitrate (γ(N) = 8.5, hypervalent) are shown below. | 4 | Stereochemistry |
Single Chain Cyclized/Knotted Polymers are a new class of polymer architecture with a general structure consisting of multiple intramolecular cyclization units within a single polymer chain. Such a structure was synthesized via the controlled polymerization of multivinyl monomers, which was first reported in Dr. Wenxin Wang's research lab. These multiple intramolecular cyclized/knotted units mimic the characteristics of complex knots found in proteins and DNA which provide some elasticity to these structures. Of note, 85% of elasticity in natural rubber is due to knot-like structures within its molecular chain. <br />
An intramolecular cyclization reaction is where the growing polymer chain reacts with a vinyl functional group on its own chain, rather than with another growing chain in the reaction system. In this way the growing polymer chain covalently links to itself in a fashion similar to that of a knot in a piece of string. As such, single chain cyclized/knotted polymers consist of many of these links (intramolecularly cyclized), as opposed to other polymer architectures including branched and crosslinked polymers that are formed by two or more polymer chains in combination.
Linear polymers can also fold into knotted topologies via non-covalent linkages. Knots and slipknots have been identified in naturally evolved polymers such as proteins as well. Circuit topology and knot theory formalise and classify such molecular conformations. | 7 | Physical Chemistry |
Rac is a subfamily of the Rho family of GTPases, small (~21 kDa) signaling G proteins (more specifically a GTPase). Just as other G proteins, Rac acts as a molecular switch, remaining inactive while bound to GDP and activated once GEFs remove GDP, permitting GTP to bind. When bound to GTP, Rac is activated. In its activated state, Rac participates in the regulation of cell movement, through its involvement in structural changes to the actin Cytoskeleton. By changing the cytoskeletal dynamics within the cell, Rac-GTPases are able to facilitate the recruitment of neutrophils to the infected tissues, and to regulate degranulation of azurophil and integrin-dependent phagocytosis.
Activated Rac also regulates the effector functions of the target proteins involved in downstream signaling. As an essential subunit of NOX2 (NADPH oxidase enzyme complex), Rac is required for ROS (reactive oxygen species) production involved in the formation of NETs (neutrophil extracellular traps, thus, facilitating the pathogen and debris clearance by neutrophils, and the reduction of inflammation.
The abnormal activities of Rac including its hyperactivation, resistance to degradation, and abnormal localization of its signaling protein components were found to facilitate the development of cancerous cells and resist to anticancer treatment.
Recent experiments on Drosophila suggested that Rac could be involved in mediating the process of forgetting. Hyperactivation of Rac increases the memory decay whereas its inhibition prevents interference-induced forgetting and slows down a passive memory decay. | 1 | Biochemistry |
According to legend, Puerto Mosquito is named after the Mosquito, the name of one of pirate Roberto Cofresí's ships. The bio bay was proclaimed a National Natural Landmark in 1980. | 1 | Biochemistry |
The δS (pronounced delta 34 S) value is a standardized method for reporting measurements of the ratio of two stable isotopes of sulfur, S:S, in a sample against the equivalent ratio in a known reference standard. Presently, the most commonly used standard is Vienna-Canyon Diablo Troilite (VCDT). Results are reported as variations from the standard ratio in parts per thousand, per mil or per mille, using the ‰ symbol. Heavy and light sulfur isotopes fractionate at different rates and the resulting δS values, recorded in marine sulfate or sedimentary sulfides, have been studied and interpreted as records of the changing sulfur cycle throughout the earth's history. | 9 | Geochemistry |
For materials that are difficult to sinter, a process called liquid phase sintering is commonly used. Materials for which liquid phase sintering is common are SiN, WC, SiC, and more. Liquid phase sintering is the process of adding an additive to the powder which will melt before the matrix phase. The process of liquid phase sintering has three stages:
*rearrangement – As the liquid melts capillary action will pull the liquid into pores and also cause grains to rearrange into a more favorable packing arrangement.
*solution-precipitation – In areas where capillary pressures are high (particles are close together) atoms will preferentially go into solution and then precipitate in areas of lower chemical potential where particles are not close or in contact. This is called contact flattening. This densifies the system in a way similar to grain boundary diffusion in solid state sintering. Ostwald ripening will also occur where smaller particles will go into solution preferentially and precipitate on larger particles leading to densification.
*final densification – densification of solid skeletal network, liquid movement from efficiently packed regions into pores.
For liquid phase sintering to be practical the major phase should be at least slightly soluble in the liquid phase and the additive should melt before any major sintering of the solid particulate network occurs, otherwise rearrangement of grains will not occur. Liquid phase sintering was successfully applied to improve grain growth of thin semiconductor layers from nanoparticle precursor films. | 8 | Metallurgy |
*CuMnAl, CuMnIn, CuMnSn
*NiMnAl, NiMnIn, NiMnSn, NiMnSb, NiMnGa
*CoMnAl, CoMnSi, CoMnGa, CoMnGe, CoNiGa, CoMnSn
*PdMnAl, PdMnIn, PdMnSn, PdMnSb
*CoFeSi, CoFeAl
*FeVAl
*MnVGa, CoFeGe
*CoCrFeX(X=Al, Si)
* YbBiPt | 8 | Metallurgy |
In pattern comparison the general shapes of electropherograms of different samples are compared for changes such as presence-absence of peaks between treatments, their relative size, etc. | 1 | Biochemistry |
DEAD is an orange-red liquid which weakens its color to yellow or colorless upon dilution or chemical reaction. This color change is conventionally used for visual monitoring of the synthesis. DEAD dissolves in most common organic solvents, such as toluene, chloroform, ethanol, tetrahydrofuran and dichloromethane but has low solubility in water or carbon tetrachloride; the solubility in water is higher for the related azo compound dimethyl azodicarboxylate.
DEAD is a strong electron acceptor and easily oxidizes a solution of sodium iodide in glacial acetic acid. It also reacts vigorously with hydrazine hydrate producing diethyl hydrazodicarboxylate and evolving nitrogen. Linear combination of atomic orbitals molecular orbital method (LCAO-MO) calculations suggest that the molecule of DEAD is unusual in having a high-lying vacant bonding orbital, and therefore tends to withdraw hydrogen atoms from various hydrogen donors. Photoassisted removal of hydrogen by DEAD was demonstrated for isopropyl alcohol, resulting in pinacol and tetraethyl tetrazanetetracarboxylate, and for acetaldehyde yielding diacetyl and diethyl hydrazodicarboxylate. Similarly, reacting DEAD with ethanol and cyclohexanol abstracts hydrogen producing acetaldehyde and cyclohexanone. Those reactions also proceed without light, although at much lower yields.
Thus, in general DEAD is an aza-dienophile and dehydrogenating agent, converting alcohols to aldehydes, thiols to disulfides and hydrazo groups to azo groups. It also undergoes pericyclic reactions with alkenes and dienes via ene and Diels–Alder mechanisms. | 0 | Organic Chemistry |
A regular solution can also be described by Raoult's law modified with a Margules function with only one parameter :
where the Margules function is
Notice that the Margules function for each component contains the mole fraction of the other component. It can also be shown using the Gibbs-Duhem relation that if the first Margules expression holds, then the other one must have the same shape. A regular solutions internal energy will vary during mixing or during process.
The value of can be interpreted as W/RT, where W = 2U - U - U represents the difference in interaction energy between like and unlike neighbors.
In contrast to ideal solutions, regular solutions do possess a non-zero enthalpy of mixing, due to the W term. If the unlike interactions are more unfavorable than the like ones, we get competition between an entropy of mixing term that produces a minimum in the Gibbs free energy at x = 0.5 and the enthalpy term that has a maximum there. At high temperatures, the entropic term in the free energy of mixing dominates and the system is fully miscible, but at lower temperatures the G(x) curve will have two minima and a maximum in between. This results in phase separation. In general there will be a temperature where the three extremes coalesce and the system becomes fully miscible. This point is known as the upper critical solution temperature or the upper consolute temperature.
In contrast to ideal solutions, the volumes in the case of regular solutions are no longer strictly additive but must be calculated from partial molar volumes that are a function of x.
The term was introduced in 1927 by the American physical chemist Joel Henry Hildebrand. | 7 | Physical Chemistry |
DNA sequences of HBsAg were obtained from 180 patients, in which 51 were chronic HBV carrier and 129 newly diagnosed patients, and compared with consensus sequences built with 168 HBV sequences imported from GenBank. Literature review and BLOSUM scores were used to define potentially altered antigenicity. | 1 | Biochemistry |
Again, define and to be conjugate pairs, and the to be the natural variables of the internal energy.
Since all of the natural variables of the internal energy are extensive quantities
it follows from Euler's homogeneous function theorem that the internal energy can be written as:
From the equations of state, we then have:
This formula is known as an Euler relation, because Euler's theorem on homogeneous functions leads to it. (It was not discovered by Euler in an investigation of thermodynamics, which did not exist in his day.).
Substituting into the expressions for the other main potentials we have:
As in the above sections, this process can be carried out on all of the other thermodynamic potentials. Thus, there is another Euler relation, based on the expression of entropy as a function of internal energy and other extensive variables. Yet other Euler relations hold for other fundamental equations for energy or entropy, as respective functions of other state variables including some intensive state variables. | 7 | Physical Chemistry |
It is apparent that both the reactor geometry and the method by which the plasma is generated strongly influence the performance of the system. | 7 | Physical Chemistry |
2-Phosphoglyceric acid (2PG), or 2-phosphoglycerate, is a glyceric acid which serves as the substrate in the ninth step of glycolysis. It is catalyzed by enolase into phosphoenolpyruvate (PEP), the penultimate step in the conversion of glucose to pyruvate. | 1 | Biochemistry |
Classical variables that do not change upon time reversal include:
:, position of a particle in three-space
:, acceleration of the particle
:, force on the particle
:, energy of the particle
:, electric potential (voltage)
:, electric field
:, electric displacement
:, density of electric charge
:, electric polarization
:Energy density of the electromagnetic field
:, Maxwell stress tensor
:All masses, charges, coupling constants, and other physical constants, except those associated with the weak force. | 7 | Physical Chemistry |
There are numerous mosses or bog habitats in Scotland, many of them situated also in Aberdeenshire, including the Cookney Moss, Leuchar Moss and Red Moss of Netherley nearby. There are also many other shires within Scotland that contain mosses such as Fife, Angus, Morayshire and Lanarkshire. Some of these are lowland bogs and others, like Portlethen Moss, are raised bogs. There are other similar acidic peat bogs in the northern part of North America, Russia and northern Europe, but in those locations they are usually called "bogs". | 2 | Environmental Chemistry |
These sweet glycosides found in the stevia plant Stevia rebaudiana Bertoni have 40–300 times the sweetness of sucrose. The two primary glycosides, stevioside and rebaudioside A, are used as natural sweeteners in many countries. These glycosides have steviol as the aglycone part. Glucose or rhamnose-glucose combinations are bound to the ends of the aglycone to form the different compounds. | 0 | Organic Chemistry |
Because radon is generally associated with diseases that are not detected until many years after elevated exposure, the public may not consider the amount of radon that children are currently being exposed to. Aside from the exposure in the home, one of the major contributors to radon exposure in children are the schools in which they attend almost every day. A survey was conducted in schools across the United States to detect radon levels, and it was estimated that about one in five schools has at least one room (more than 70,000 schoolrooms) with short-term levels above 4pCi/L.
Many states have active radon testing and mitigation programs in place, which require testing in buildings such as public schools. However, these are not standardized nationwide, and the rules and regulations on reducing high radon levels are even less common. The School Health Policies and Practices Study (SHPPS), conducted by the CDC in 2012, found that of schools located in counties with high predicted indoor radon levels, only 42.4% had radon testing policies, and a mere 37.5% had policy for radon-resistant new construction practices. Only about 20% of all schools nationwide have done testing, even though the EPA recommends that every school be tested. These numbers are arguably not high enough to ensure protection of the majority of children from elevated radon exposures. For exposure standards to be effective, they should be set for those most susceptible. | 2 | Environmental Chemistry |
In chemistry, a supramolecular assembly is a complex of molecules held together by noncovalent bonds. While a supramolecular assembly can be simply composed of two molecules (e.g., a DNA double helix or an inclusion compound), or a defined number of stoichiometrically interacting molecules within a quaternary complex, it is more often used to denote larger complexes composed of indefinite numbers of molecules that form sphere-, rod-, or sheet-like species. Colloids, liquid crystals, biomolecular condensates, micelles, liposomes and biological membranes are examples of supramolecular assemblies, and their realm of study is known as supramolecular chemistry. The dimensions of supramolecular assemblies can range from nanometers to micrometers. Thus they allow access to nanoscale objects using a bottom-up approach in far fewer steps than a single molecule of similar dimensions.
The process by which a supramolecular assembly forms is called molecular self-assembly. Some try to distinguish self-assembly as the process by which individual molecules form the defined aggregate. Self-organization, then, is the process by which those aggregates create higher-order structures. This can become useful when talking about liquid crystals and block copolymers. | 6 | Supramolecular Chemistry |
The sodium fusion test, or Lassaigne's test, is used in elemental analysis for the qualitative determination of the presence of foreign elements, namely halogens, nitrogen, and sulfur, in an organic compound. It was developed by J. L. Lassaigne.
The test involves heating the sample with sodium metal, "fusing" it with the sample. A variety of techniques has been described. The "fused" sample is plunged into water, and the qualitative tests are performed on the resultant solution for the respective possible constituents. | 3 | Analytical Chemistry |
Although the chemical composition of the primitive mantle cannot be directly measured at its source, researchers have been able to estimate primitive mantle characteristics using a few methods. One methodology involves the analysis of chondritic meteorites that represent early Earth chemical composition and creating models using the analyzed chemical characteristics and assumptions describing inner-Earth dynamics. This approach is based on the assumption that early planetary bodies in the solar system formed under similar conditions, giving them comparable chemical compositions. The more direct methodology is to observe trends in the chemical makeup of upper mantle peridotites and interpret the hypothetical composition of the primitive mantle based on these trends. This is done by matching the peridotite compositional trends to the distribution of refractory lithophile elements (which are not affected by core-mantle differentiation) in chondritic meteorites. Both methods have limitations based on the assumptions made about inner-earth, as well as statistical uncertainties in the models used to quantify the data.
The two approaches detailed above yield weight percentages that follow the same general trends when compared to the depleted (or homogeneous) mantle: the primitive mantle has significantly higher concentrations of SiO AlO, NaO, and CaO, and significantly lower concentrations of MgO. More importantly, both approaches show that the primitive mantle has much greater concentrations of refractory lithophile elements (e.g Al, Ba, Be, Ca, Hf, Nb, Sc, Sr, Ta, Th, Ti, U, Y, Zr, and rare earth elements). The exact concentrations of these compounds and refractory lithophile elements depends on the estimation method used. Methods using peridotite analysis yield a much smaller primitive mantle weight percentage for SiO and significantly larger primitive mantle weight percentages for MgO and AlO than those estimated using direct chondritic meteorite analysis. The estimated concentrations of refractory lithophile elements obtained from the two methods vary as well, usually 0.1-5 ppm. | 9 | Geochemistry |
The book was first published by Profile Books in 2015. The British edition was subtitled with the question of the title, "Why is Life the Way it is?", whereas the American edition was subtitled with the explanation "Energy, Evolution, and the Origins of Complex Life". A paperback edition came out in 2016. The book has been translated into at least seven languages: Chinese, German, Japanese, Korean, Polish, Spanish, and Turkish. | 1 | Biochemistry |
Crop rotation can help restore tilth in compacted soils. Two processes contribute to this gain. First, accelerated organic matter decomposition from tillage ends under the sod crop. Another way to achieve this is via no-till farming. Second, grass and legume sods develop extensive root systems that continually grow and die off. The dead roots supply a source of active organic matter, which feeds soil organisms that create aggregation – the soil carbon sponge. Beneficial organisms need continual supplies of organic matter to sustain themselves and they deposit the digested materials on soil aggregates and thereby stabilize them. Also, the living roots and symbiotic microorganisms (for example, mycorrhizal fungi) can exude organic materials that nourish soil organisms and help with aggregation. Grass and legume sod crops therefore deposit more organic matter in the soil than most other crops.
Some annual rotation crops such as buckwheat also have dense, fibrous, root systems and can improve tilth. Crop mixtures with different rooting systems can be beneficial. For example, red clover seeded into winter wheat provide additional roots and a more protein-rich soil organic matter.
Other rotation crops are more valuable for improving subsoils. Perennial crops such as alfalfa have strong, deep, penetrating tap roots that can push through hard layers, especially during wet periods when the soil is soft. These deep roots establish pathways for water and future plant roots, and produce soil organic matter.
Crops rotation can extend the period of active growth compared to conventional row crops, leaving more organic material behind. For example, in a corn-soybean rotation, active growth occurs 32% of the time, while a dry bean–winter wheat–corn rotation is active 72% of the time. Crops such as rye, wheat, oat, barley, pea and cool-season grasses grow actively in the late fall and early spring when other crops are inactive. They are beneficial both as rotation and cover crops, although intensive tillage can negate their effects. | 9 | Geochemistry |
Differences in plant disease resistance are often incremental or quantitative rather than qualitative. The term quantitative resistance (QR) refers to plant disease resistance that is controlled by multiple genes and multiple molecular mechanisms that each have small or minor effects on the overall resistance trait. QR is important in plant breeding because the resulting resistance is often more durable (effective for more years), and more likely to be effective against most or all strains of a particular pathogen. QR is typically effective against one pathogen species or a group of closely related species, rather than being broadly effective against multiple pathogens. QR is often obtained through plant breeding without knowledge of the causal genetic loci or molecular mechanisms. QR is likely to depend on many of the plant immune system components discussed in this article, as well as traits that are unique to certain plant-pathogen pairings (such as sensitivity to certain pathogen effectors), as well as general plant traits such as leaf surface characteristics or root system or plant canopy architecture. The term QR is synonymous with minor gene resistance. | 1 | Biochemistry |
In the case of an idealized two-level atom the detailed balance for the emission and absorption which preserves the Planck formula for the black-body radiation leads to equality of cross-section of absorption and emission. In the solid-state lasers the splitting of each of laser levels leads to the broadening which greatly exceeds the natural spectral linewidth. In the case of an ideal two-level atom, the product of the linewidth and the lifetime is of order of unity, which obeys the Heisenberg uncertainty principle. In solid-state laser materials, the linewidth is several orders of magnitude larger so the spectra of emission and absorption are determined by distribution of excitation among sublevels rather than by the shape of the spectral line of each individual transition between sublevels. This distribution is determined by the effective temperature within each of laser levels. The McCumber hypothesis is that the distribution of excitation among sublevels is thermal. The effective temperature determines the spectra of emission and absorption ( The effective temperature is called a temperature by scientists even if the excited medium as whole is pretty far from the thermal state ) | 7 | Physical Chemistry |
Planck (1914, page 40) refers to a condition of thermodynamic equilibrium, in which "any two bodies or elements of bodies selected at random exchange by radiation equal amounts of heat with each other."
The term radiative exchange equilibrium can also be used to refer to two specified regions of space that exchange equal amounts of radiation by emission and absorption (even when the steady state is not one of thermodynamic equilibrium, but is one in which some sub-processes include net transport of matter or energy including radiation). Radiative exchange equilibrium is very nearly the same as Prevost's relative radiative equilibrium. | 7 | Physical Chemistry |
Cold-adapted arctic frogs, such as wood frogs, and some other ectotherms in polar and subpolar regions naturally produce glucose, but southern brown tree frogs and Arctic salamanders create glycerol in their livers to reduce ice formation.
When glucose is used as a cryoprotectant by arctic frogs, massive amounts of glucose are released at low temperature and a special form of insulin allows for this extra glucose to enter the cells. When the frog rewarms during spring, the extra glucose must be rapidly eliminated, but stored. | 1 | Biochemistry |
Fura-2-acetoxymethyl ester, often abbreviated Fura-2AM, is a membrane-permeant derivative of the ratiometric calcium indicator Fura-2 used in biochemistry to measure cellular calcium concentrations by fluorescence. When added to cells, Fura-2AM crosses cell membranes and once inside the cell, the acetoxymethyl groups are removed by cellular esterases. Removal of the acetoxymethyl esters regenerates "Fura-2", the pentacarboxylate calcium indicator. Measurement of Ca-induced fluorescence at both 340 nm and 380 nm allows for calculation of calcium concentrations based 340/380 ratios. The use of the ratio automatically cancels out certain variables such as local differences in fura-2 concentration or cell thickness that would otherwise lead to artifacts when attempting to image calcium concentrations in cells. | 1 | Biochemistry |
AMOC is driven by ocean temperature and salinity differences. The major possible mechanism causing the cold ocean surface temperature anomaly is based on the fact that freshwater decreases ocean water salinity, and through this process prevents colder waters sinking. Observed freshwater increase originates probably from Greenland ice melt. | 9 | Geochemistry |
This is a classical use of thermal mass. Examples include adobe, rammed earth, or limestone block houses. Its function is highly dependent on marked diurnal temperature variations. The wall predominantly acts to retard heat transfer from the exterior to the interior during the day. The high volumetric heat capacity and thickness prevents thermal energy from reaching the inner surface. When temperatures fall at night, the walls re-radiate the thermal energy back into the night sky. In this application it is important for such walls to be massive to prevent heat transfer into the interior. | 7 | Physical Chemistry |
Molecular oxygen is a good terminal electron acceptor because it is a strong oxidizing agent. The reduction of oxygen does involve potentially harmful intermediates. Although the transfer of four electrons and four protons reduces oxygen to water, which is harmless, transfer of one or two electrons produces superoxide or peroxide anions, which are dangerously reactive.
These reactive oxygen species and their reaction products, such as the hydroxyl radical, are very harmful to cells, as they oxidize proteins and cause mutations in DNA. This cellular damage may contribute to disease and is proposed as one cause of aging.
The cytochrome c oxidase complex is highly efficient at reducing oxygen to water, and it releases very few partly reduced intermediates; however small amounts of superoxide anion and peroxide are produced by the electron transport chain. Particularly important is the reduction of coenzyme Q in complex III, as a highly reactive ubisemiquinone free radical is formed as an intermediate in the Q cycle. This unstable species can lead to electron "leakage" when electrons transfer directly to oxygen, forming superoxide. As the production of reactive oxygen species by these proton-pumping complexes is greatest at high membrane potentials, it has been proposed that mitochondria regulate their activity to maintain the membrane potential within a narrow range that balances ATP production against oxidant generation. For instance, oxidants can activate uncoupling proteins that reduce membrane potential.
To counteract these reactive oxygen species, cells contain numerous antioxidant systems, including antioxidant vitamins such as vitamin C and vitamin E, and antioxidant enzymes such as superoxide dismutase, catalase, and peroxidases, which detoxify the reactive species, limiting damage to the cell. | 1 | Biochemistry |
His father was a military physician. He was a student of Academician . In 1940, he defended his Candidate's Dissertation at the N.D. Zelinsky Institute of Organic Chemistry. In 1949, he defended his doctoral dissertation. From 1950 to 1992, Perekalin headed the Department of Organic Chemistry at the Herzen University. In this University he organized the Faculty of Chemistry. He taught in the Herzen University for 48 years. In 1995, he was appointed Soros Professor.
He has a son Pyotr.
Perekalin is the author of more than 350 scientific papers. | 0 | Organic Chemistry |
Dichloromethane, . There is a rotation axis which passes through the carbon atom and the midpoints between the two hydrogen atoms and the two chlorine atoms. Define the z axis as co-linear with the axis, the plane as containing and the plane as containing . A rotation operation permutes the two hydrogen atoms and the two chlorine atoms. Reflection in the plane permutes the hydrogen atoms while reflection in the plane permutes the chlorine atoms. The four symmetry operations , , and form the point group . Note that if any two operations are carried out in succession the result is the same as if a single operation of the group had been performed.
Methane, . In addition to the proper rotations of order 2 and 3 there are three mutually perpendicular axes which pass half-way between the C-H bonds and six mirror planes. Note that | 7 | Physical Chemistry |
Hattori argued that the prevailing view for volcano formation in arcs ic arc formation, that water is released rapidly from subducting slabs when they are metamorphosed to eclogite facies, is inconsistent with geological evidence. Instead, she proposed an alternative mechanism, suggesting that water is continuously released from slabs and stored as serpentinites (hydrated mantle rocks) and stressed that the subsequent dehydration of these serpentinites triggers the formation of arc volcanoes. Her work has established the importance and distribution of serpentinites on the major ocean floors, which control seismic activity and may potentially have played a role in the origin of life on the planet.
Additionally, Hattori's work highlighted that heavy metals and metalloids, such as arsenic and antimony, are generally considered to be concentrated in sulphides, but under sulphur-deficient conditions, these elements behave like normal rock-forming elements. | 9 | Geochemistry |
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