text
stringlengths 105
4.44k
| label
int64 0
9
| label_text
stringclasses 10
values |
|---|---|---|
Intrinsically disordered proteins (IDPs) have very limited innate structure in solution but gain shape specifically when interacting with partner molecules such as proteins or RNA; however, their resultant structure is often dictated by this interaction. In addition, some proteins have sections of sequence without structure, termed intrinsically disordered regions (IDRs), that also gain structure on interaction. Having different shapes with different partners means they are functionally, as well as structurally flexible, making them centrally important to signalling pathways and as regulation/control factors for example. IDPs (and IDRs if capable of being isolated from the rest of the protein) have a distinct SRCD spectral appearance in solution which means that changes in their spectra that arise through interactions offer an ideal opportunity to gain insight into what is happening both structurally and functionally. In addition, SRCD studies have demonstrated that when the solvating water is removed from these proteins, generating a film, there is a gain in structure and more CD transition bands can be measured into the lower VUV wavelength region because the water absorption band is not present
Myelin is the insulating sheath that is formed in the central (CNS) and peripheral nervous systems (PNS) to surround nerve cell axons thereby increasing and maintaining the electrical impulse, the action potential, sent along them. Formed mostly of lipids, there are specific proteins within the myelin components whose roles are to structure the myelin into linked layers. Two of these proteins are myelin basic protein (MBP), an IDP primarily in the CNS, and myelin protein zero (P0) which contains an IDR section (P0ct) and is key within the PNS. MBP and P0ct were employed in a study which used SRCD data as a key factor to establish if there was any significance to the predictions of their IDP and IDR protein structures generated by Alphafold2, an artificial intelligence program developed by DeepMind. PDB2CD, a package that generates SRCD spectra from protein atomic coordinates, was used to calculate spectra from the Alphafold2 structures, and these spectra were then compared against SRCD experimental spectra collected from the MBP and P0ct proteins in various ambient conditions; solution, detergent and lipid-bound states. The study reported that from the SRCD comparisons, the structures predicted by Alphafold2 for MBP and P0ct bore a strong resemblance to those when they were bound to the lipid membrane. | 7 | Physical Chemistry |
Blocked isocyanates are organic compounds that have their isocyanate functionality chemically blocked to control reactivity. They are the product of an isocyanate moiety (nearly always a di-isocyanate) and a suitable blocking agent. It may also be a polyurethane prepolymer that is NCO terminated but this functionality has also been chemically reacted with a blocking agent.
They are usually used in polyurethane applications but not always. They are extensively used in industrial applications such as coatings, sealants and adhesives. | 0 | Organic Chemistry |
Consider quantum chromodynamics (QCD) with two massless quarks and (massive fermions do not exhibit chiral symmetry). The Lagrangian reads
In terms of left-handed and right-handed spinors, it reads
(Here, is the imaginary unit and the Dirac operator.)
Defining
it can be written as
The Lagrangian is unchanged under a rotation of q by any 2×2 unitary matrix , and q by any 2×2 unitary matrix .
This symmetry of the Lagrangian is called flavor chiral symmetry, and denoted as . It decomposes into
The singlet vector symmetry, , acts as
and thus invariant under gauge symmetry. This corresponds to baryon number conservation.
The singlet axial group transforms as the following global transformation
However, it does not correspond to a conserved quantity, because the associated axial current is not conserved. It is explicitly violated by a quantum anomaly.
The remaining chiral symmetry turns out to be spontaneously broken by a quark condensate
formed through nonperturbative action of QCD gluons, into the diagonal vector subgroup known as isospin. The Goldstone bosons corresponding to the three broken generators are the three pions.
As a consequence, the effective theory of QCD bound states like the baryons, must now include mass terms for them, ostensibly disallowed by unbroken chiral symmetry. Thus, this chiral symmetry breaking induces the bulk of hadron masses, such as those for the nucleons — in effect, the bulk of the mass of all visible matter.
In the real world, because of the nonvanishing and differing masses of the quarks, is only an approximate symmetry to begin with, and therefore the pions are not massless, but have small masses: they are pseudo-Goldstone bosons. | 4 | Stereochemistry |
* Alfred P. Sloan Fellow, 1961-65
* NSF Senior Postdoctoral Fellow, 1968-69
* Heinrich Hertz Fellow (West Germany)
* Meyerhoff Fellow (Israel)
* Fellow of the American Physical Society, citation: For his many contributions to the statistical mechanics of transport processes, especially to the understanding of Brownian motion and the couplings of moving molecules, 1983. | 7 | Physical Chemistry |
The base-catalyzed reaction of 3-sulfolene with carbon dioxide at 3 bar pressure produces 3-sulfolene-3-carboxylic acid in 45% yield.
With diazomethane, 3-sulfolene forms in a 1,3-dipolar cycloadduct: | 0 | Organic Chemistry |
David Henry Solomon (born 19 November 1929 in Adelaide, South Australia) is an Australian polymer chemist. He is best known for his work in developing Living Radical Polymerization techniques, and polymer banknotes. | 7 | Physical Chemistry |
In the gas phase sulfur dioxide is oxidized by reaction with the hydroxyl radical via an intermolecular reaction:
:SO + OH· → HOSO·
which is followed by:
:HOSO· + O → HO· + SO
In the presence of water, sulfur trioxide (SO) is converted rapidly to sulfuric acid:
:SO (g) + HO (l) → HSO (aq)
Nitrogen dioxide reacts with OH to form nitric acid:
:NO + OH· → HNO | 2 | Environmental Chemistry |
The multicopper active site of CP contains a type I (T1) mononuclear copper site and a trinuclear copper center ~ 12-13 Å away (see figure 2). The tricopper center consists of two type III (T3) coppers and one type II (T2) copper ion. The two T3 copper ions are bridged by a hydroxide ligand while another hydroxide ligand links the T2 copper ion to the protein. The T1 center is bridged to the tricopper center by two histidine (His1020, His1022) residues and one Cys(1021) residue. The substrate binds near the T1 center and is oxidized by the T1 Cu ion forming the reduced Cu oxidation state. The reduced T1 Cu then transfers the electron through the one Cys and two His bridging residues to the tricopper center. After four electrons have been transferred from the substrates to the copper centers, an O binds at the tricopper center and undergoes a four-electron reduction to form two molecules of water. | 1 | Biochemistry |
The first two STAT proteins were identified in the interferon system. There are seven mammalian STAT family members that have been identified: STAT1, STAT2, STAT3, STAT4, STAT5 (STAT5A and STAT5B), and STAT6.
STAT1 homodimers are involved in type II interferon signalling, and bind to the GAS (Interferon-Gamma Activated Sequence) promoter to induce expression of interferon stimulated genes (ISG). In type I interferon signaling, STAT1-STAT2 heterodimer combines with IRF9 (Interferon Response Factor) to form ISGF3 (Interferon Stimulated Gene Factor), which binds to the ISRE (Interferon-Stimulated Response Element) promoter to induce ISG expression. | 1 | Biochemistry |
Polybutene is an organic polymer made from a mixture of 1-butene, 2-butene, and isobutylene. Ethylene steam cracker C4s are also used as supplemental feed for polybutene. It is similar to polyisobutylene (PIB), which is produced from essentially pure isobutylene made in a C4 complex of a major refinery. The presence of isomers other than isobutylene can have several effects including: 1) lower reactivity due to steric hindrance at the terminal carbon in, e.g., manufacture of polyisobutenyl succinic anhydride (PIBSA) dispersant manufacture; 2) the molecular weight—viscosity relationships of the two materials may also be somewhat different. | 7 | Physical Chemistry |
Colloid-facilitated transport designates a transport process by which colloidal particles serve as transport vector
of diverse contaminants in the surface water (sea water, lakes, rivers, fresh water bodies) and in underground water circulating in fissured rocks
(limestone, sandstone, granite, ...). The transport of colloidal particles in surface soils and in the ground can also occur, depending on the soil structure, soil compaction, and the particles size, but the importance of colloidal transport was only given sufficient attention during the 1980 years.
Radionuclides, heavy metals, and organic pollutants, easily sorb onto colloids suspended in water and that can easily act as contaminant carrier.
Various types of colloids are recognised: inorganic colloids (clay particles, silicates, iron oxy-hydroxides, ...), organic colloids (humic and fulvic substances). When heavy metals or radionuclides form their own pure colloids, the term "Eigencolloid" is used to designate pure phases, e.g., Tc(OH), Th(OH), U(OH), Am(OH). Colloids have been suspected for the long range transport of plutonium on the Nevada Nuclear Test Site. They have been the subject of detailed studies for many years. However, the mobility of inorganic colloids is very low in compacted bentonites and in deep clay formations
because of the process of ultrafiltration occurring in dense clay membrane.
The question is less clear for small organic colloids often mixed in porewater with truly dissolved organic molecules. | 7 | Physical Chemistry |
Both sexual and asexual reproductions are implemented. Asexual reproduction is implemented as producing the offsprings genome (the gene network) by directly copying the parents genome. Sexual reproduction is implemented as the recombination of the two parents' genomes. | 1 | Biochemistry |
The US Department of Defense developed favipiravir in partnership with MediVector, Inc. as a broad-spectrum antiviral and sponsored it through FDA Phase II and Phase III clinical trials, where it demonstrated safety in humans and efficacy against the influenza virus. favipiravir remains unapproved in the UK and the USA. In 2014, Japan approved favipiravir for treating influenza strains unresponsive to current antivirals. Toyama Chemical initially hoped that favipiravir would become a new influenza medication that could replace oseltamivir (brand name Tamiflu). However, animal experiments show the potential for teratogenic effects, and the approval of production by The Ministry of Health, Labor and Welfare was greatly delayed and the production condition is limited only in an emergency in Japan.
Despite limited data on efficacy, as of March 2021 favipiravir is widely prescribed for outpatient treatment of mild to moderate COVID-19 in Egypt, Hungary and Serbia. Patients are required to sign a consent form before obtaining the drug. | 4 | Stereochemistry |
Hydrogen for the reduction of C=N double bond can either be provided by hydrogen gas (H) or transferred from sources of H, such as alcohols and formic acid. The process is usually catalyzed by transition metal complexes. For metal catalyzed reactions, the transfer of H to the imine can proceed by either inner sphere or outer sphere mechanisms. | 0 | Organic Chemistry |
The first mesoionic carbenes based on pyrazole have been reported by Huynh in 2007. These carbenes are referred to as pyrazolin-3(or 4)-ylidenes. Pyrazolin-4-ylidenes are often tetrasubstituted with alkyl or aryl groups; however, the C3 and C5 positions could be substituted with nitrogen- or oxygen-based groups. The electronic properties of the groups in the C3 and C5 positions affect the overall electron properties of the ligand and influence catalytic activity. Free carbene have been produced as well as transition metal complexes. | 0 | Organic Chemistry |
Dicarbaboranes can be prepared from boron hydrides using alkynes as the source of the two carbon centers. In addition to the closo- series mentioned above, several open-cage dicarbon species are known including nido- (isostructural and isoelectronic with ) and arachno-.
Syntheses of icosahedral closo-dicarbadodecaborane derivatives () employ alkynes as the source and decaborane () to supply the unit. | 7 | Physical Chemistry |
The oldest known blast furnaces in the West were built in Durstel in Switzerland, the Märkische Sauerland in Germany, and at Lapphyttan in Sweden, where the complex was active between 1205 and 1300. At Noraskog in the Swedish parish of Järnboås, traces of even earlier blast furnaces have been found, possibly from around 1100. These early blast furnaces, like the Chinese examples, were very inefficient compared to those used today. The iron from the Lapphyttan complex was used to produce balls of wrought iron known as osmonds, and these were traded internationally – a possible reference occurs in a treaty with Novgorod from 1203 and several certain references in accounts of English customs from the 1250s and 1320s. Other furnaces of the 13th to 15th centuries have been identified in Westphalia.
The technology required for blast furnaces may have either been transferred from China, or may have been an indigenous innovation. Al-Qazvini in the 13th century and other travellers subsequently noted an iron industry in the Alburz Mountains to the south of the Caspian Sea. This is close to the silk route, so that the use of technology derived from China is conceivable. Much later descriptions record blast furnaces about three metres high. As the Varangian Rus' people from Scandinavia traded with the Caspian (using their Volga trade route), it is possible that the technology reached Sweden by this means. The Vikings are known to have used double bellows, which greatly increases the volumetric flow of the blast.
The Caspian region may also have been the source for the design of the furnace at Ferriere, described by Filarete, involving a water-powered bellows at Semogo in Valdidentro in northern Italy in 1226. In a two-stage process the molten iron was tapped twice a day into water, thereby granulating it. | 8 | Metallurgy |
RNA polymerase III uses a very similar factor to TFIIB called Brf (TFIIB-related factor) which also contains a conserved zinc ribbon and C terminal core. However, the structure diverges in the more flexible linker region although Brf still contains highly conserved sequences in the same positions that the B reader and B linker are found. These conserved regions probably carry out similar functions as the domains in TFIIB. RNA polymerase I does not use a factor that is similar to TFIIB; however, it is thought that another unknown factor fulfils the same function.
There is no direct homologue for TFIIB in bacterial systems but there are proteins that bind the bacterial polymerase in a similar manner with no sequence similarity. In particular the bacterial protein σ70 contains domains that bind the polymerase at the same points as the B-linker, B-ribbon and B-core. This is especially apparent in the σ 3 region and the region 4 linker which might stabilise the DNA in the polymerase active site. | 1 | Biochemistry |
DKPs are synthesized by a wide range of organisms, including bacteria, fungi, more complex marine microorganisms, and even mammals. However, 90% of gram-negative bacteria synthesize these molecules, making them the target of most studies. | 0 | Organic Chemistry |
Transforming growth factor beta-1-induced transcript 1 protein is a protein that in humans is encoded by the TGFB1I1 gene. Often put together with and studied alongside TGFB1I1 is the mouse homologue HIC-5 ( Hydrogen Peroxide-Inducible Clone-5). As the name suggests, TGFB1I1 is an induced form of the larger family of TGFB1. Studies suggest TGFB1I1 plays a role in processes of cell growth, proliferation, migration, differentiation and senescence. TGFB1I1 is most localized at focal adhesion complexes of cells, although it may be found active in the cytosol, nucleus and cell membrane as well. | 1 | Biochemistry |
Little is known about an effective way to overcoming hyperacute rejection (HAR), which follows the activation of complement initiated by xenoreactive antibodies recognizing galactosyl-alpha1-3galatosyl (alpha-Gal) antigens on the donor epithelium. | 1 | Biochemistry |
Contrastingly, reversible electroporation occurs when the electricity applied with the electrodes is below the electric field threshold of the target tissue. Because the electricity applied is below the cells' threshold, it allows the cells to repair their phospholipid bilayer and continue on with their normal cell functions. Reversible electroporation is typically done with treatments that involve getting a drug or gene (or other molecule that is not normally permeable to the cell membrane) into the cell. Not all tissue has the same electric field threshold; therefore careful calculations need to be made prior to a treatment to ensure safety and efficacy.
One major advantage of using N-TIRE is that, when done correctly according to careful calculations, it only affects the target tissue. Proteins, the extracellular matrix, and critical structures such as blood vessels and nerves are all unaffected and left healthy by this treatment. This allows for a quicker recovery, and facilitates a more rapid replacement of dead tumor cells with healthy cells.
Before doing the procedure, scientists must carefully calculate exactly what needs to be done and treat each patient on an individual case-by-case basis. To do this, imaging technology such as CT scans and MRI's are commonly used to create a 3D image of the tumor. From this information, they can approximate the volume of the tumor and decide on the best course of action including the insertion site of electrodes, the angle they are inserted in, the voltage needed, and more, using software technology. Often, a CT machine will be used to help with the placement of electrodes during the procedure, particularly when the electrodes are being used to treat tumors in the brain.
The entire procedure is very quick, typically taking about five minutes. The success rate of these procedures is high and is very promising for future treatment in humans. One disadvantage to using N-TIRE is that the electricity delivered from the electrodes can stimulate muscle cells to contract, which could have lethal consequences depending on the situation. Therefore, a paralytic agent must be used when performing the procedure. The paralytic agents that have been used in such research are successful; however, there is always some risk, albeit slight, when using anesthetics. | 1 | Biochemistry |
Common treatments used for toxic substance ingestions are ineffective, or are even harmful, when implemented in ingestions of caustic substances. Clinical attempts to empty the stomach can cause further injuries. Activated charcoal does not neutralize caustics and can also obscure endoscopic visualization. There is no known clinical benefit of neutralization of the caustic substances; neutralization releases heat as well as causing gaseous distention and vomiting, all of which can worsen injuries.
Signs of airway compromise including decreased level of consciousness, stridor, change in voice, inability to control oral secretions necessitate intubation and mechanical ventillation. IV fluids are often needed to maintain hydration and replace insensible water losses.
Endoscopy should be done within the first 24–48 hours of ingestion as subsequent wound softening increases the risk of perforation. Endoscopically inserted nasogastric tubes can serve as a stent to prevent esophageal strictures as well as allow tube feedings. A CT scan, often enhanced with contrast, can also be used to evaluate injuries.
The most common surgical methods of treatment in children include esophageal dilation and esophageal replacement as less commonly implantation of an esophageal stent. | 8 | Metallurgy |
Methylidyne, or (unsubstituted) carbyne, is an organic compound whose molecule consists of a single hydrogen atom bonded to a carbon atom. It is the parent compound of the carbynes, which can be seen as obtained from it by substitution of other functional groups for the hydrogen.
The carbon atom is left with either one or three unpaired electrons (unsatisfied valence bonds), depending on the molecule's excitation state; making it a radical. Accordingly, the chemical formula can be CH or CH (also written as ⫶CH); each dot representing an unpaired electron. The corresponding systematic names are methylylidene or hydridocarbon(•), and methanetriyl or hydridocarbon(3•). However, the formula is often written simply as CH.
Methylidyne is a highly reactive gas, that is quickly destroyed in ordinary conditions but is abundant in the interstellar medium (and was one of the first molecules to be detected there). | 0 | Organic Chemistry |
In 2000, Steglich et al. reported an intramolecular Pd(II)-mediated decarboxylative cross-coupling reaction in their synthesis of lamellarin L.
Myers et al. reported decarboxylative olefination of ortho-substituted arene carboxylates in the presence of an oxidant (Ag2CO3) in 2002.
Subsequent studies showed that homogeneous Pd catalysts were able to decarboxylate acids at lower temperatures than their Cu and Ag counterparts, but were limited to electron rich ortho-substituted aromatic carboxylic acids.
Despite this, palladium catalysts are able to promote a wide variety of cross-coupling reactions including biaryl formation and aryl alkyne formation, along with a variety of cross-coupling reactions in which the carboxylic acid is not bonded to an aromatic.
Other Pd-catalyzed decarboxylation cross-coupling reactions include conjugated diene preparation (see dienes and trienes below) and dehydrogenative reactions (with a variety of substrate and catalyst combinations).
Contrarily to Cu-only systems, decarboxylative palladation is the rate-limiting step in the palladium catalytic cycle. | 0 | Organic Chemistry |
Lilleby smelteverk was a smeltmill located in Lilleby, Trondheim, Sør-Trøndelag county, Norway, next to City Lade. It is well known for having produced the world's cleanest ferrosilicon (an alloy that contains iron and silicon) for NASA. Shut down in December 20th, 2002, the production moved to Mo I Rana.
The building is demolished. | 8 | Metallurgy |
Carboxypeptidase E is found in all species of vertebrates that have been examined, and is also present in many other organisms that have been studied (nematode, sea slug). Carboxypeptidase E is not found in the fruit fly (Drosophila), and another enzyme (presumably carboxypeptidase D) fills in for carboxypeptidase E in this organism. In humans, CPE is encoded by the CPE gene. | 1 | Biochemistry |
The first efforts that can be considered photogeochemical research can be traced to the "formaldehyde hypothesis" of Adolf von Baeyer in 1870, in which formaldehyde was proposed to be the initial product of plant photosynthesis, formed from carbon dioxide and water through the action of light on a green leaf. This suggestion inspired numerous attempts to obtain formaldehyde in vitro, which can retroactively be considered photogeochemical studies. Detection of organic compounds such as formaldehyde and sugars was reported by many workers, usually by exposure of a solution of carbon dioxide to light, typically a mercury lamp or sunlight itself. At the same time, many other workers reported negative results. One of the pioneer experiments was that of Bach in 1893, who observed the formation of lower uranium oxides upon irradiation of a solution of uranium acetate and carbon dioxide, implying the formation of formaldehyde. Some experiments included reducing agents such as hydrogen gas, and others detected formaldeyhde or other products in the absence of any additives, although the possibility was admitted that reducing power may have been produced from the decomposition of water during the experiment. In addition to the main focus on synthesis of formaldehyde and simple sugars, other light-assisted reactions were occasionally reported, such as the decomposition of formaldehyde and subsequent release of methane, or the formation of formamide from carbon monoxide and ammonia.
In 1912 Benjamin Moore summarized the main facet of photogeochemistry, that of inorganic photocatalysis: "the inorganic colloid must possess the property of transforming sunlight, or some other form of radiant energy, into chemical energy." Many experiments, still focused on how plants assimilate carbon, did indeed explore the effect of a "transformer" (catalyst); some effective "transformers" were similar to naturally occurring minerals, including iron(III) oxide or colloidal iron hydroxide; cobalt carbonate, copper carbonate, nickel carbonate; and iron(II) carbonate. Working with an iron oxide catalyst, Baly concluded in 1930 that "the analogy between the laboratory process and that in the living plant seems therefore to be complete," referring to his observation that in both cases, a photochemical reaction takes place on a surface, the activation energy is supplied in part by the surface and in part by light, efficiency decreases when the light intensity is too great, the optimal temperature of the reaction is similar to that of living plants, and efficiency increases from the blue to the red end of the light spectrum.
At this time, however, the intricate details of plant photosynthesis were still obscure, and the nature of photocatalysis in general was still actively being discovered; Mackinney in 1932 stated that "the status of this problem [photochemical CO reduction] is extraordinarily involved." As in many emerging fields, experiments were largely empirical, but the enthusiasm surrounding this early work did lead to significant advances in photochemistry. The simple but challenging principle of transforming solar energy into chemical energy capable of performing a desired reaction remains the basis of application-based photocatalysis, most notably artificial photosynthesis (production of solar fuels).
After several decades of experiments centered around the reduction of carbon dioxide, interest began to spread to other light-induced reactions involving naturally occurring materials. These experiments usually focused on reactions analogous to known biological processes, such as soil nitrification, for which the photochemical counterpart "photonitrification" was first reported in 1930. | 5 | Photochemistry |
This technique is commonly used in conjunction with green fluorescent protein (GFP) fusion proteins, where the studied protein is fused to a GFP. When excited by a specific wavelength of light, the protein will fluoresce. When the protein that is being studied is produced with the GFP, then the fluorescence can be tracked. Photodestroying the GFP, and then watching the repopulation into the bleached area can reveal information about protein interaction partners, organelle continuity and protein trafficking.
If after some time the fluorescence doesn't reach the initial level anymore, then some part of the fluorescence is caused by an immobile fraction (that cannot be replenished by diffusion). Similarly, if the fluorescent proteins bind to static cell receptors, the rate of recovery will be retarded by a factor related to the association and disassociation coefficients of binding. This observation has most recently been exploited to investigate protein binding. Similarly, if the GFP labeled protein is constitutively incorporated into a larger complex, the dynamics of fluorescence recovery will be characterized by the diffusion of the larger complex. | 1 | Biochemistry |
"Oil rents" have been described as connected with corruption in political literature. A 2011 study suggested that increases in oil rents increased corruption in countries with heavy government involvement in the production of oil. The study found that increases in oil rents "significantly deteriorates political rights". The investigators say that oil exploitation gave politicians "an incentive to extend civil liberties but reduce political rights in the presence of oil windfalls to evade redistribution and conflict". | 7 | Physical Chemistry |
Fluorite (CaF), also called fluorspar, is the main source of commercial fluorine. Fluorite is a colorful mineral associated with hydrothermal deposits. It is common and found worldwide. China supplies more than half of the world's demand and Mexico is the second-largest producer in the world.
The United States produced most of the world's fluorite in the early 20th century, but its last mine, in Illinois, shut down in 1995. Canada also exited production in the 1990s. The United Kingdom has declining fluorite mining and has been a net importer since the 1980s. | 9 | Geochemistry |
Joule heating (also known as resistive, resistance, or Ohmic heating) is the process by which the passage of an electric current through a conductor produces heat.
Joules first law (also just Joules law), also known in countries of the former USSR as the Joule–Lenz law, states that the power of heating generated by an electrical conductor equals the product of its resistance and the square of the current. Joule heating affects the whole electric conductor, unlike the Peltier effect which transfers heat from one electrical junction to another.
Joule-heating or resistive-heating is used in multiple devices and industrial process. The part that converts electricity into heat is called a heating element.
Among the many practical uses are:
* An incandescent light bulb glows when the filament is heated by Joule heating, due to thermal radiation (also called blackbody radiation).
* Electric fuses are used as a safety, breaking the circuit by melting if enough current flows to melt them.
* Electronic cigarettes vaporize propylene glycol and vegetable glycerine by Joule heating.
* Multiple heating devices use Joule heating, such as electric stoves, electric heaters, soldering irons, cartridge heaters.
* Some food processing equipment may make use of Joule heating: running current through food material (which behave as an electrical resistor) causes heat release inside the food. The alternating electrical current coupled with the resistance of the food causes the generation of heat. A higher resistance increases the heat generated. Ohmic heating allows for fast and uniform heating of food products, which maintains quality. Products with particulates heat up faster (compared to conventional heat processing) due to higher resistance. | 7 | Physical Chemistry |
While humans are highly dependent upon visual cues, when in close proximity smells also play a role in sociosexual behaviors. An inherent difficulty in studying human pheromones is the need for cleanliness and odorlessness in human participants. Though various researchers have investigated the possibility of their existence, no pheromonal substance has ever been demonstrated to directly influence human behavior in a peer reviewed study. Experiments have focused on three classes of possible human pheromones: axillary steroids, vaginal aliphatic acids, and stimulators of the vomeronasal organ, including [https://academic.oup.com/scan/article/14/7/719/5532402 this 2018 study] claiming pheromones affect men's sexual cognition. | 1 | Biochemistry |
Proteins have many different functions in a cell and the function may vary based on the polypeptides they interact with and their cellular environment. Chaperone proteins work to stabilize newly synthesized proteins. They ensure the new protein folds into its correct functional conformation in addition to making sure products do not aggregate in areas where they should not. Proteins can also function as enzymes, increasing the rate of various biochemical reactions and turning substrates into products. Products can be modified by attaching groups such as phosphate via an enzyme to specific amino acids in the primary sequence. Proteins can also be used to move molecules in the cell to where they are needed, these are called motor proteins. The shape of the cell is supported by proteins. Proteins such as actin, microtubules and intermediate filaments provide structure to the cell. Another class of proteins are found in plasma membranes. Membrane proteins can be associated with the plasma membrane in different ways, depending on their structure. These proteins allow the cell to import or export cell products, nutrients or signals to and from the extracellular space. Other proteins help the cell to perform regulatory functions. For example, transcription factors bind to DNA to help transcription of RNA. | 1 | Biochemistry |
Doubly-expanded (or naphtho-homologated) nucleobases incorporate a naphthalene spacer instead of a benzene ring, widening the base twice as much with its two-ringed structure. These structures (known as xxDNA and yyDNA) are 4.8Å wider than natural bases and were once again created as a result of Leonard's research on expanded adenine in ATP-dependent enzymes in 1984. No literature was published on these doubly-expanded bases for nearly three decades until 2013 when the first xxG was produced by Sharma, Lait, and Wetmore and incorporated along with xxA into a natural helix. Although very little research has been performed on xxDNA, xx-purine neighbours have already been shown to increase intrastrand stacking energy by up to 119% (as opposed to 62% in x-purines). xx-purine and pyrimidine interactions show an overall decrease in stacking energies, but the overall stability of duplexes including pyrimidines and xx-purines increases by 22%, more than twofold that of pyrimidines and x-purines. | 1 | Biochemistry |
Nitroalkenes are synthesized by various means, notable examples include:
* Nitroaldol reactions such as the Henry reaction:
* Nitration of an alkene with nitryl iodide generated in-situ from silver nitrite and elemental iodine:
* Direct nitration of alkenes with nitric oxide and an aluminum oxide catalyst in acidic conditions:
*Direct nitration of alkenes with Clayfen (Iron(III) nitrate supported on Montmorillonite clay):
* Dehydration of nitro-alcohols: | 0 | Organic Chemistry |
Within the realm of bioorganometallic chemistry is the study of the fates of synthetic organometallic compounds. Tetraethyllead has received considerable attention in this regard as has its successors such as methylcyclopentadienyl manganese tricarbonyl. Methylmercury is a particularly infamous case; this cation is produced by the action of vitamin B-related enzymes on mercury. | 0 | Organic Chemistry |
A pH meter is a scientific instrument that measures the hydrogen-ion activity in water-based solutions, indicating its acidity or alkalinity expressed as pH. The pH meter measures the difference in electrical potential between a pH electrode and a reference electrode, and so the pH meter is sometimes referred to as a "potentiometric pH meter". The difference in electrical potential relates to the acidity or pH of the solution. Testing of pH via pH meters (pH-metry) is used in many applications ranging from laboratory experimentation to quality control. | 7 | Physical Chemistry |
Photosensitizers absorb light (hν) and transfer the energy from the incident light into another nearby molecule either directly or by a chemical reaction. Upon absorbing photons of radiation from incident light, photosensitizers transform into an excited singlet state. The single electron in the excited singlet state then flips in its intrinsic spin state via Intersystem crossing to become an excited triplet state. Triplet states typically have longer lifetimes than excited singlets. The prolonged lifetime increases the probability of interacting with other molecules nearby. Photosensitizers experience varying levels of efficiency for intersystem crossing at different wavelengths of light based on the internal electronic structure of the molecule. | 5 | Photochemistry |
John Douglas Eshelby FRS (21 December 1916 – 10 December 1981) was a scientist in micromechanics. He made significant contributions to the fields of defect mechanics and micromechanics of inhomogeneous solids for fifty years, including important aspects of the controlling mechanisms of plastic deformation and fracture. | 8 | Metallurgy |
This form factor is useful for any applications where the spectrum analyzer needs to be taken outside to make measurements or simply carried while in use. Attributes that contribute to a useful portable spectrum analyzer include:
*Optional battery-powered operation to allow the user to move freely outside.
*Clearly viewable display to allow the screen to be read in bright sunlight, darkness or dusty conditions.
*Light weight (usually less than ). | 7 | Physical Chemistry |
Vanadyl ribonucleoside is a potent transition-state analog of ribonucleic acid and potent inhibitor of many species of ribonuclease formed from a vanadium coordination complex and one ribonucleoside. Vanadium's [ 4s electron configuration allows it to make five sigma bonds and two pi bonds with adjacent atoms. | 1 | Biochemistry |
Early mining operations often did not take adequate steps to make tailings areas environmentally safe after closure. Modern mines, particularly those in jurisdictions with well-developed mining regulations and those operated by responsible mining companies, often include the rehabilitation and proper closure of tailings areas in their costs and activities. For example, the Province of Quebec, Canada, requires not only the submission of a closure plan before the start of mining activity, but also the deposit of a financial guarantee equal to 100% of the estimated rehabilitation costs. Tailings dams are often the most significant environmental liability for a mining project.
Mine tailings may have economic value in carbon sequestration due to the large exposed surface area of the minerals. | 8 | Metallurgy |
An action potential is a spike of both positive and negative ionic discharge that travels along the membrane of a cell. The creation and conduction of action potentials represents a fundamental means of communication in the nervous system. Action potentials represent rapid reversals in voltage across the plasma membrane of axons. These rapid reversals are mediated by voltage-gated ion channels found in the plasma membrane.
The action potential travels from one location in the cell to another, but ion flow across the membrane occurs only at the nodes of Ranvier. As a result, the action potential signal jumps along the axon, from node to node, rather than propagating smoothly, as they do in axons that lack a myelin sheath. The clustering of voltage-gated sodium and potassium ion channels at the nodes permits this behavior. | 1 | Biochemistry |
Chetsanga has discovered two enzymes involved in the repair of damaged DNA: firstly, formamidopyrimidine DNA glycosylase, which removes damaged 7-methylguanine from DNA (1979), and secondly, purine imidazole-ring cyclase, which re-closes imidazole rings of guanine and adenine damaged by x-irradiation (1985).
According to Chetsanga, his research focus in his scientific career has been on DNA and RNA structural and functional details as they relate to cellular metabolism and disease development. | 1 | Biochemistry |
For strong electrolytes, a single reaction arrow shows that the reaction occurs completely in one direction, in contrast to the dissociation of weak electrolytes, which both ionize and re-bond in significant quantities.
Strong electrolytes conduct electricity only when molten or in aqueous solutions.
Strong electrolytes break apart into ions completely.
The stronger an electrolyte the greater the voltage produced when used in a galvanic cell. | 3 | Analytical Chemistry |
Foodomics approach is used to analyze and establish the links between several substances presented in rosemary and the ability to cure colon cancer cells. There are thousands of chemical compounds in rosemary, but the ones that are able to help cure such disease are Carnosic acid (CA) and Carnosol (CS), which can be obtained by extracting rosemary via SFE. They have the potential to fight against and reduce the proliferation of human HT-29 colon cancer cells.
The experiment done by inserting rosemary extracts to the mice and collecting RNA and metabolites from each controlled and treated individual indicated that there is a correlation between the compounds used and the percentage of recovery from the cancer. This information is however never achievable without the help of foodomics knowledge as it was used to process data, analyze statistic, and identify biomarkers. Foodomics, coupled with transcriptomic data, shows that Carnosic acid leads to the accumulation of an antioxidant, glutothione (GSH). The chemical can be broken down to Cysteinylglycine, a naturally occurring dipeptide and an intermediate in the gamma glutamyl cycle. Moreover, the result from an integration of foodomics, transcriptomics and metabolomics reveals that provoking colon cancer cell compounds, such as N‐acetylputrescine, N‐acetylcadaverine, 5’MTA and γ‐aminobutyric acid, can also be lowered by CA treatment.
Thus, foodomics plays an important role in explaining the relationship between deadly disease, like colon cancer, and natural compounds existing in rosemary. Data obtained is useful in reaching another approach for tackling proliferation against cancer cells. | 1 | Biochemistry |
Amino acid biosynthesis is the set of biochemical processes (metabolic pathways) by which the amino acids are produced. The substrates for these processes are various compounds in the organism's diet or growth media. Not all organisms are able to synthesize all amino acids. For example, humans can synthesize 11 of the 20 standard amino acids. These 11 are called the non-essential amino acids). | 1 | Biochemistry |
Autoantibodies may be produced against the body's own snRNPs, most notably the anti-Sm antibodies targeted against the Sm protein type of snRNP specifically in systemic lupus erythematosus (SLE). | 1 | Biochemistry |
Respirometry depends on a "what goes in must come out" principle. Consider a closed system first. Imagine that we place a mouse into an air-tight container. The air sealed in the container initially contains the same composition and proportions of gases that were present in the room: 20.95% O, 0.04% CO, water vapor (the exact amount depends on air temperature, see dew point), 78% (approximately) N, 0.93% argon and a variety of trace gases making up the rest (see Earth's atmosphere). As time passes, the mouse in the chamber produces CO and water vapor, but extracts O from the air in proportion to its metabolic demands. Therefore, as long as we know the volume of the system, the difference between the concentrations of O and CO at the start when we sealed the mouse into the chamber (the baseline or reference conditions) compared to the amounts present after the mouse has breathed the air at a later time must be the amounts of CO/O produced/consumed by the mouse. Nitrogen and argon are inert gasses and therefore their fractional amounts are unchanged by the respiration of the mouse. In a closed system, the environment will eventually become hypoxic. | 1 | Biochemistry |
A widespread current model of the evolution of the first living organisms is that these were some form of prokaryotes, which may have evolved out of protocells, while the eukaryotes evolved later in the history of life. Some authors have questioned this conclusion, arguing that the current set of prokaryotic species may have evolved from more complex eukaryotic ancestors through a process of simplification.
Others have argued that the three domains of life arose simultaneously, from a set of varied cells that formed a single gene pool. This controversy was summarized in 2005:
The oldest known fossilized prokaryotes were laid down approximately 3.5 billion years ago, only about 1 billion years after the formation of the Earth's crust. Eukaryotes only appear in the fossil record later, and may have formed from endosymbiosis of multiple prokaryote ancestors. The oldest known fossil eukaryotes are about 1.7 billion years old. However, some genetic evidence suggests eukaryotes appeared as early as 3 billion years ago.
While Earth is the only place in the universe where life is known to exist, some have suggested that there is evidence on Mars of fossil or living prokaryotes. However, this possibility remains the subject of considerable debate and skepticism. | 1 | Biochemistry |
In mainland China, modafinil is strictly controlled like other stimulants such as amphetamines and methylphenidate. It is classified as Class I psychotropic drug. This classification means that modafinil is considered to have a high potential for abuse and dependence, and is therefore subject to strict regulation and control. As a result, modafinil is only available by prescription and cannot be purchased over the counter. In order to obtain a prescription for modafinil, a patient must have a valid medical reason for using the drug, such as narcolepsy or sleep apnea. Additionally, the prescription must be written by a licensed physician and filled at a licensed pharmacy. The use of modafinil for non-medical purposes, such as with the aim to improve cognitive performance or to stay awake for long periods of time, is strictly prohibited and can result in legal consequences. | 4 | Stereochemistry |
The ACV frequency is used to monitor the Faradaic current, which quantifies target binding. The generation of signal has been reported to be insensitive to ACV frequency as long as the ACV is in a sensible range, therefore, not too low to be detected or too fast. The ACV frequency is used instead of a single-directional current to protect the degradation of the electrodes. Square wave voltammetry is applied and measured to analyze the change in current as the voltage is swept linearly across an electrode. | 7 | Physical Chemistry |
Water is the most abundant substance on Earths surface and also the third most abundant molecule in the universe, after and . 0.23 ppm of the earths mass is water and 97.39% of the global water volume of 1.38 km is found in the oceans.
Water is far more prevalent in the outer Solar System, beyond a point called the frost line, where the Suns radiation is too weak to vaporize solid and liquid water (as well as other elements and chemical compounds with relatively low melting points, such as methane and ammonia). In the inner Solar System, planets, asteroids, and moons formed almost entirely of metals and silicates. Water has since been delivered to the inner Solar System via an as-yet unknown mechanism, theorized to be the impacts of asteroids or comets carrying water from the outer Solar System, where bodies contain much more water ice. The difference between planetary bodies located inside and outside the frost line can be stark. Earths mass is 0.000023% water, while Tethys, a moon of Saturn, is almost entirely made of water. | 2 | Environmental Chemistry |
Indigo carmine, or 5,5′-indigodisulfonic acid sodium salt, is an organic salt derived from indigo by aromatic sulfonation, which renders the compound soluble in water. It is approved for use as a food colorant in the United States and European Union to produce a blue color. It has the E number E132, and is named Blue No. 2 by the Federal Food, Drug, and Cosmetic Act. It is also a pH indicator. | 3 | Analytical Chemistry |
A major advantage of DamID over ChIP seq is that profiling of protein binding sites can be assayed in a particular cell type in vivo without requiring the physical separation of a subpopulation of cells. This allows for investigation into developmental or physiological processes in animal models. | 1 | Biochemistry |
The Dhar iron pillar is a now-fragmented iron column located in the Dhar town of Madhya Pradesh, India. The exact origins of the pillar are unknown, but according to the local tradition, it was a victory column erected by the 11th century Paramara king Bhoja.
Three of its fragments are now located near the 15th century Lat Masjid ("pillar mosque"), which is named after the pillar (called "lāṭ" in Hindi). A fourth portion is believed to be missing. The original pillar tapered from bottom to top: the bottom fragment has a square cross-section; the middle fragment has square and octagonal cross-sections, and the top fragment has an octagonal cross-section with a small circular part at the end. The total length of the three fragments is , which indicates that the original pillar must have been twice as high as the iron pillar of Delhi. The combined weight of the fragments is estimated at around , which is at least more than the Delhi pillar's weight. At the time of its erection, it was probably the largest forge-welded iron pillar in the world. | 8 | Metallurgy |
A focused laser beam rotates in a constant frequency and interacts with particles within the sample medium.
Each randomly scanned particle obscures the laser beam to its dedicated photo diode, which measures the time of obscuration.
The time of obscuration directly relates to the particle's Diameter, by a simple calculation principle of multiplying the known beam rotation Velocity in the directly measured Time of obscuration, (D=V*t). | 7 | Physical Chemistry |
In the current biosphere, the most common electron donors are organic molecules. Organisms that use organic molecules as an electron source are called organotrophs. Chemoorganotrophs (animals, fungi, protists) and photolithotrophs (plants and algae) constitute the vast majority of all familiar life forms.
Some prokaryotes can use inorganic matter as an electron source. Such an organism is called a (chemo)lithotroph ("rock-eater"). Inorganic electron donors include hydrogen, carbon monoxide, ammonia, nitrite, sulfur, sulfide, manganese oxide, and ferrous iron. Lithotrophs have been found growing in rock formations thousands of meters below the surface of Earth. Because of their volume of distribution, lithotrophs may actually outnumber organotrophs and phototrophs in our biosphere.
The use of inorganic electron donors such as hydrogen as an energy source is of particular interest in the study of evolution. This type of metabolism must logically have preceded the use of organic molecules and oxygen as an energy source. | 1 | Biochemistry |
When the DNA hairpin is unzipped into single-strand, oligonucleotides complementary to the hairpin sequence are allowed to hybridize. During the time course of the rezipping process, the bound oligonucleotides cause transient blockages. The time course measurement of hairpin length allows for the determination of the exact position of the hybridization, as well as the presence of mismatches between the oligonucleotide and the hairpin. | 1 | Biochemistry |
Silyl ethers are a group of chemical compounds which contain a silicon atom covalently bonded to an alkoxy group. The general structure is RRRSi−O−R where R is an alkyl group or an aryl group. Silyl ethers are usually used as protecting groups for alcohols in organic synthesis. Since RRR can be combinations of differing groups which can be varied in order to provide a number of silyl ethers, this group of chemical compounds provides a wide spectrum of selectivity for protecting group chemistry. Common silyl ethers are: trimethylsilyl (TMS), tert-butyldiphenylsilyl (TBDPS), tert-butyldimethylsilyl (TBS/TBDMS) and triisopropylsilyl (TIPS). They are particularly useful because they can be installed and removed very selectively under mild conditions. | 0 | Organic Chemistry |
In molecular biology, quantitation of nucleic acids is commonly performed to determine the average concentrations of DNA or RNA present in a mixture, as well as their purity. Reactions that use nucleic acids often require particular amounts and purity for optimum performance. To date, there are two main approaches used by scientists to quantitate, or establish the concentration, of nucleic acids (such as DNA or RNA) in a solution. These are spectrophotometric quantification and UV fluorescence tagging in presence of a DNA dye. | 7 | Physical Chemistry |
Mutations and loss of function of the Von Hippel-Lindau (VHL) tumor suppressor gene play a causal role in the pathogenesis of clear cell renal carcinomas (ccRCC), a pathological subtype that accounts for the majority kidney cancer each year. Mollapour work has shown that VHL ubiquitinates protein phosphatase-5 (PP5) for proteasomal degradation in a hypoxia- and prolyl-hydroxylation-independent manner. VHL-deficient ccRCC cell lines and patient tumors exhibit elevated PP5 levels. Downregulation of PP5 causes activation of the extrinsic apoptotic pathway in ccRCC cells, suggesting a prosurvival role for PP5 in kidney cancer.
Mollapour’s research group has been supported by grants from the National Institutes for General Medical Science and the National Cancer Institute to design and examine novel therapeutic strategies for patients with kidney, bladder and breast cancer. | 1 | Biochemistry |
Although no large studies showing the long term outcomes for women with hyperthecosis exist, a diagnosis of hyperthecosis may suggest an increased risk for metabolic complications of hyperlipidemia and type 2 diabetes . In postmenopausal women, hyperthecosis may also contribute to the pathogenesis of endometrial polyp, endometrial hyperplasia, and endometrioid adenocarcinoma due to the association of hyperestrinism (excess estrins in the body) and hyperthecosis. Treatment for hyperthecosis is based upon each case, but may range from pharmacological interventions to surgical. | 1 | Biochemistry |
Beginning in 1867, a lichen ( , ) was understood as a symbiosis of an algae or cyanobacteria, living among filaments of multiple fungi species. In 2016, new research by T. Spribille et al. revealed a third partner, a yeast imbedded in the lichen cortex or "skin."
Lichens are important actors in nutrient cycling and act as producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); grow crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); have a powder-like appearance (leprose); or other growth forms.
A macrolichen is a lichen that is either bush-like or leafy; all other lichens are termed microlichens. Here, "macro" and "micro" do not refer to size, but to the growth form. Common names for lichens may contain the word moss (e.g., "reindeer moss", "Iceland moss"), and lichens may superficially look like and grow with mosses, but they are not closely related to mosses or any plant. Lichens do not have roots that absorb water and nutrients as plants do, but like plants, they produce their own nutrition by photosynthesis. When they grow on plants, they do not live as parasites, but instead use the plant's surface as a substrate.
Lichens occur from sea level to high alpine elevations, in many environmental conditions, and can grow on almost any surface. They are abundant growing on bark, leaves, mosses, or other lichens and hanging from branches "living on thin air" (epiphytes) in rainforests and in temperate woodland. They grow on rock, walls, gravestones, roofs, exposed soil surfaces, rubber, bones, and in the soil as part of biological soil crusts. Various lichens have adapted to survive in some of the most extreme environments on Earth: arctic tundra, hot dry deserts, rocky coasts, and toxic slag heaps. They can even live inside solid rock, growing between the grains (endolithic).
It is estimated that 6–8% of Earth's land surface is covered by lichens. There are about 20,000 known species. Some lichens have lost the ability to reproduce sexually, yet continue to speciate. They can be seen as being relatively self-contained miniature ecosystems, where the fungi, algae, or cyanobacteria have the potential to engage with other microorganisms in a functioning system that may evolve as an even more complex composite organism. Lichens may be long-lived, with some considered to be among the oldest living things. They are among the first living things to grow on fresh rock exposed after an event such as a landslide. The long life-span and slow and regular growth rate of some species can be used to date events (lichenometry). Lichens are a keystone species in many ecosystems and benefit trees and birds. | 2 | Environmental Chemistry |
The regulation of Snf3 in S. cerevisiae and its downstream events are still poorly understood, but it seems clear that a second glucose sensor Rgt2 influences Snf3 and vice versa. Furthermore, it is unclear whether these two proteins sense the glucose concentration on the outside or inside the cell. Snf3 and Rgt2 influence directly or indirectly several Hxt-transporters which are responsible for the glucose uptake. Low extracellular glucose concentrations are sensed by the Snf3 protein which probably leads to the expression of Hxt2-Genes for high affinity glucose transporters, while Rgt2 senses high glucose concentrations and leads to the expression of low affinity glucose transporters, like Hxt1 Although the downstream pathway is poorly understood it seems that Snf3 and Rgt2 transmit a signal directly or indirectly to Grr1, the DNA binding protein Rgt1, and the two cofactors Ssn6 and Tup1. Also needed for the transcription are the two nuclear proteins Mth1 and Std1. | 1 | Biochemistry |
Type B, S, R and K thermocouples are used extensively in the steel and iron industries to monitor temperatures and chemistry throughout the steel making process. Disposable, immersible, type S thermocouples are regularly used in the electric arc furnace process to accurately measure the temperature of steel before tapping. The cooling curve of a small steel sample can be analyzed and used to estimate the carbon content of molten steel. | 8 | Metallurgy |
The goniometric SPR method was researched alongside focused beam SPR and Otto configurations at VTT Technical Research Centre of Finland since 1980s by Dr. Janusz Sadowski. The goniometric SPR optics was commercialized by Biofons Oy for use in point-of-care applications. Introduction of additional measurement laser wavelengths and first thin film analyses were performed in 2011 giving way to MP-SPR method. | 7 | Physical Chemistry |
A Criegee intermediate (also called a Criegee zwitterion or Criegee biradical) is a carbonyl oxide with two charge centers. These chemicals may react with sulfur dioxide and nitrogen oxides in the Earth's atmosphere, and are implicated in the formation of aerosols, which are an important factor in controlling global climate. Criegee intermediates are also an important source of OH (hydroxyl radicals). OH radicals are the most important oxidant in the troposphere, and are important in controlling air quality and pollution.
The formation of this sort of structure was first postulated in the 1950s by Rudolf Criegee, for whom it is named. It was not until 2012 that direct detection of such chemicals was reported. Infrared spectroscopy suggests the electronic structure has a substantially zwitterionic character rather than the biradical character that had previously been proposed. | 2 | Environmental Chemistry |
Pestiviruses have a single stranded, positive-sense RNA genomes. They cause Classical swine fever (CSF) and Bovine viral diarrhea(BVD). Mucosal disease is a distinct, chronic persistent infection, whereas BVD is an acute infection. | 1 | Biochemistry |
Thiosulfonates are organosulfur compounds with the formula RSOSR'. Thiosulfonate esters are produced by oxidation of disulfides or the nucleophilic attack of thiolates on organosulfonyl halides.
Alkali metal thiosulfonates are the conjugate base of thiosulfuric acid. They are prepared by the reaction of organosulfonyl chlorides with sources of sulfide.
Oxidation with mCPBA gives disulfones. | 0 | Organic Chemistry |
Interleukin 10 is produced by regulatory T lymphocytes, B cells, and monocytes. It is a homodimer that functions through the IL-10R1 and IL-10R2 receptor complexes, activating such kinases as Janus kinase and tyrosine kinase 2. IL-10R2 receptor is presented in most cells, when IL-10R1 receptor is IL-10 is also an inhibitor of expressions of CD80 and CD86 by dendritic cells (DC) and antigen-presenting cells (APC), and of T cells, decreasing their cytokine production, therefore, controlling their activation. IL-10 plays a big role in regulating allergies by inhibiting cytokines responsible for allergic inflammation. | 1 | Biochemistry |
Enolate ions are more useful than enols for two reasons. First, pure enols can't normally be isolated but are instead generated only as short lived intermediates in low concentration. By contrast, stable solutions of pure enolate ions
are easily prepared from most carbonyl compounds by reaction with a strong base. Second, enolate ions are more reactive than enols and undergo many reactions that enols don't. Whereas enols are neutral, enolate ions are negatively charged, making them much better nucleophiles. As a result, enolate ions are more common than enols in both laboratory and biological chemistry.
Because they are resonance hybrids of two nonequivalent forms, enolate ions can be looked at either as vinylic alkoxides (C=C- O) or as α-ketocarbanions (C-C= O). Thus, enolate ions can react with electrophiles either on oxygen or on carbon. Reaction on oxygen yields an enol derivative, while reaction on carbon yields an α-substituted carbonyl compound. Both kinds of reactivity are known, but reaction on carbon is more common. | 0 | Organic Chemistry |
*Gadd45a was discovered and characterized in the laboratory of Dr. Albert J. Fornace Jr. in 1988.
*Gadd45b (MyD118) was discovered and characterized in the laboratories of Drs. Dan A. Liebermann and Barbara Hoffman in 1991.
*Gadd45g (CR6) was discovered and characterized in the laboratories of Drs. Kenneth Smith, Dan A. Liebermann, and Barbara Hoffman in 1993 and 1999. | 1 | Biochemistry |
PAC is one of the artificial chromosome vectors. Some other artificial chromosomes include: bacterial artificial chromosome, yeast artificial chromosome and the human artificial chromosome. Compared to other artificial chromosomes, it can carry relatively large DNA fragments, however less so than the yeast artificial chromosome(YAC). Some advantages of PACs compared to YACs includes easier manipulation of bacteria system, easier separation from DNA hosts, higher transformation rate, more stable inserts, and they are non-chimeric which means they do not rearrange and ligate to form new DNA strand, allowing for a user friendly vector choice. | 1 | Biochemistry |
In biochemistry, the hydrophobic effect can be used to separate mixtures of proteins based on their hydrophobicity. Column chromatography with a hydrophobic stationary phase such as phenyl-sepharose will cause more hydrophobic proteins to travel more slowly, while less hydrophobic ones elute from the column sooner. To achieve better separation, a salt may be added (higher concentrations of salt increase the hydrophobic effect) and its concentration decreased as the separation progresses. | 6 | Supramolecular Chemistry |
Divergent synthesis refers to the sequential "growth" of a dendrimer layer by layer, starting with a core "initiator" molecule which contains functional groups capable of acting as active sites in the initial reaction. Each subsequent reaction in the series increases the number of available surface groups exponentially. Core molecules which give rise to PAMAM dendrimers can vary, but the most basic initiators are ammonia and ethylene diamine. Outward growth of PAMAM dendrimers is accomplished by alternating between two reactions:
# Michael addition of the amino-terminated surface onto methyl acrylate, resulting in an ester-terminated outer layer, and
# Coupling with ethylene diamine to achieve a new amino-terminated surface.
Each round of reactions forms a new "generation", and PAMAM dendrimers are often classified by generation number; the common shorthand for this classification is "GX" or "GX PAMAM", where X is a number referring to the generation number. The first full cycle of Michael addition followed by coupling with ethylene diamine forms Generation 0 PAMAM, with subsequent Michael additions giving rise to "half" generations, and subsequent amide coupling giving rise to "full" (integer) generations.
With divergent synthesis of dendrimers, it is extremely important to allow each reaction to proceed to completion; any defects caused by incomplete reaction or intramolecular coupling of new surface amines with unreacted methyl ester surface groups could cause "trailing" generations, stunting further growth for certain branches. These impurities are difficult to remove when using the divergent synthetic approach because the molecular weight, physical size, and chemical properties of the defective dendrimers are very similar in nature to the desired product. As generation number increases, it becomes more difficult to produce pure products in a timely fashion due to steric constraints. As a result, synthesis of higher-generation PAMAM dendrimers can take months. | 6 | Supramolecular Chemistry |
Brinelling is the permanent indentation of a hard surface. It is named after the Brinell scale of hardness, in which a small ball is pushed against a hard surface at a preset level of force, and the depth and diameter of the mark indicates the Brinell hardness of the surface. Brinelling is permanent plastic deformation of a surface, and usually occurs while two surfaces in contact are stationary (such as rolling elements and the raceway of a bearings) and the material yield strength has been exceeded.
Brinelling is undesirable, as the parts often mate with other parts in very close proximity. The very small indentations can quickly lead to improper operation, such as chattering or excess vibration, which in turn can accelerate other forms of wear, such as spalling and ultimately, failure of the bearing. | 8 | Metallurgy |
Prior to 1882, the South Island of New Zealand had been experimenting with sowing grass and crossbreeding sheep, which immediately gave their farmers economic potential in the exportation of meat. In 1882, the first successful shipment of sheep carcasses was sent from Port Chalmers in Dunedin, New Zealand, to London. By the 1890s, the frozen meat trade became increasingly more profitable in New Zealand, especially in Canterbury, where 50% of exported sheep carcasses came from in 1900. It was not long before Canterbury meat was known for the highest quality, creating a demand for New Zealand meat around the world. In order to meet this new demand, the farmers improved their feed so sheep could be ready for the slaughter in only seven months. This new method of shipping led to an economic boom in New Zealand by the mid 1890s.
In the United States, the Meat Inspection Act of 1891 was put in place in the United States because local butchers felt the refrigerated railcar system was unwholesome. When meat packing began to take off, consumers became nervous about the quality of the meat for consumption. Upton Sinclairs 1906 novel The Jungle' brought negative attention to the meat packing industry, by drawing to light unsanitary working conditions and processing of diseased animals. The book caught the attention of President Theodore Roosevelt, and the 1906 Meat Inspection Act was put into place as an amendment to the Meat Inspection Act of 1891. This new act focused on the quality of the meat and environment it is processed in. | 7 | Physical Chemistry |
The epiglottis is a flap of elastic cartilage attached to the entrance of the larynx. It is covered with a mucous membrane and there are taste buds on its lingual surface which faces into the mouth. Its laryngeal surface faces into the larynx. The epiglottis functions to guard the entrance of the glottis, the opening between the vocal folds. It is normally pointed upward during breathing with its underside functioning as part of the pharynx, but during swallowing, the epiglottis folds down to a more horizontal position, with its upper side functioning as part of the pharynx. In this manner it prevents food from going into the trachea and instead directs it to the esophagus, which is behind. During swallowing, the backward motion of the tongue forces the epiglottis over the glottis' opening to prevent any food that is being swallowed from entering the larynx which leads to the lungs; the larynx is also pulled upwards to assist this process. Stimulation of the larynx by ingested matter produces a strong cough reflex in order to protect the lungs. | 1 | Biochemistry |
Because of the great importance of many types of CIA spectra in planetary and astrophysical research, a well known spectroscopy database (HITRAN) has been expanded to include a number of CIA spectra in various frequency bands and for a variety of temperatures. | 7 | Physical Chemistry |
The relaxosome is the complex of proteins that facilitates plasmid transfer during bacterial conjugation. The proteins are encoded by the tra operon on a fertility plasmid in the region near the origin of transfer, oriT. The most important of these proteins is relaxase, which is responsible for beginning the conjugation process by cutting at the nic site via transesterification. This nicking results in a DNA-Protein complex with the relaxosome bound to a single strand of the plasmid DNA and an exposed 3' hydroxyl group. Relaxase also unwinds the plasmid being conjugated with its helicase properties. The relaxosome interacts with integration host factors within the oriT.
Other genes that code for relaxosome components include TraH, which stabilizes the relaxosomes structural formation, TraI, which encodes for the relaxase protein, TraJ, which recruits the complex to the oriT site, TraK, which increases the nicked state of the target plasmid, and TraY, which imparts single-stranded DNA character on the oriT site. TraM plays a particularly important role in relaxase interaction by stimulating relaxed' DNA formation. | 1 | Biochemistry |
By analyzing the emissivity of ground surfaces, multispectral imaging can detect the presence of underground missiles. Surface and sub-surface soil possess different physical and chemical properties that appear in spectral analysis. Disturbed soil has increased emissivity in the wavelength range of 8.5 to 9.5 micrometers while demonstrating no change in wavelengths greater than 10 micrometers. The US Army Research Laboratorys dual MWIR/LWIR FPA used "red" and "blue" detectors to search for areas with enhanced emissivity. The red detector acts as a backdrop, verifying realms of undisturbed soil areas, as it is sensitive to the 10.4 micrometer wavelength. The blue detector is sensitive to wavelengths of 9.3 micrometers. If the intensity of the blue image changes when scanning, that region is likely disturbed.' The scientists reported that fusing these two images increased detection capabilities. | 7 | Physical Chemistry |
Some DNA viruses encode a recombinase that facilitates homologous recombination. A well-studied example is the UvsX recombinase encoded by bacteriophage T4. UvsX is homologous to bacterial RecA. UvsX, like RecA, can facilitate the assimilation of linear single-stranded DNA into an homologous DNA duplex to produce a D-loop. | 1 | Biochemistry |
Lignite-tar creosote is produced from lignite rather than bituminous coal, and varies considerably from coal-tar creosote. Also called "lignite oil", it has a very high content of tar acids, and has been used to increase the tar acids in normal creosote when necessary. When it has been produced, it has generally been applied in mixtures with coal-tar creosote or petroleum. Its effectiveness when used alone has not been established. In an experiment with southern yellow pine fence posts in Mississippi, straight lignite-tar creosote was giving good results after about 27 years exposure, although not as good as the standard coal-tar creosote used in the same situation. | 7 | Physical Chemistry |
Early mechanistic studies from the 1960s elucidated several key points:
# No H/D exchange effects seen in this reaction. Experiments using CD in water generate CDCDO, and runs with CH in DO generate CHCHO. Thus, keto-enol tautomerization is not a possible mechanistic step.
# Negligible kinetic isotope effect with fully deuterated reactants (=1.07). Hence, it is inferred that hydride transfer is not rate-determining.
# Significant competitive isotope effect with CHD, (= ~1.9), suggests that rate determining step be prior to formation of acetaldehyde.
# High concentrations of chloride and copper(II) chloride favor formation of a new product, chlorohydrin.
Many mechanistic studies on the Wacker process have focused on pathway for formation of the C-O bond, the hydroxypalladation step. Henry inferred that coordinated hydroxide attacks the ethylene ligand, an internal (syn-) pathway. Later, stereochemical studies by Stille and coworkers support an anti-addition pathway, whereby free hydroxide attacks the ethylene ligand. The conditions for Stille's experiments differ significantly from industrial process conditions. Other studies using normal industrial Wacker conditions (except with high chloride and high copper chloride concentrations) also yielded products that inferred nucleophilic attack was an anti-addition reaction.
Kinetic studies were conducted on isotopically substituted allyl alcohols at standard industrial conditions (with low-chloride concentrations) to probe the reaction mechanisms. Those results showed that nucleophilic attack is a slow process, while the proposed mechanisms explaining the earlier stereochemical studies assumed nucleophilic attack to be a fast process.
Subsequent stereochemical studies indicated that both pathways occur and are dependent on chloride concentrations. However, these studies too are disputed since allyl-alcohols may be sensitive to isomerization reactions, and different stereoisomers may be formed from those reactions and not from the standard Wacker process.
In summary, experimental evidence seems to support that syn-addition occurs under low-chloride reaction concentrations (< 1 mol/L, industrial process conditions), while anti-addition occurs under high-chloride (> 3mol/L) reaction concentrations, probably due to chloride ions saturating the catalyst and inhibiting the inner-sphere mechanism. However, the exact pathway and the reason for this switching of pathways is still unknown.
Further complicating the Wacker process mechanism is questions about the role of copper chloride. Most theories assumed copper does not play a role in the olefin oxidation mechanisms. Yet, experiments by Stangl and Jira found chlorohydrin formation was dependent on copper chloride concentrations. Work by Hosokawa and coworkers yielded a crystallized product containing copper chloride, indicating it may have a non-innocent role in olefin oxidation. Finally, an ab initio study by Comas-Vives, et al. involving no copper co-catalyst found anti-addition was the preferred pathway. This pathway was later confirmed by copper-free experiments by Anderson and Sigman. A different kinetic rate law with no proton dependence was found under copper-free conditions, indicating the possibility that even small amounts of copper co-catalysts may have non-innocent roles on this chemistry. While these works complicate the picture of the Wacker process mechanism, one should probably infer that this and related chemistry can be sensitive to reaction conditions, and multiple different reaction pathways may be in play.
Another key step in the Wacker process is the migration of the hydrogen from oxygen to chloride and formation of the C-O double bond. This step is generally thought to proceed through a so-called β-hydride elimination with a cyclic four-membered transition state:
In silico studies argue that the transition state for this reaction step is unfavorable and an alternative reductive elimination reaction mechanism is in play. The proposed reaction steps are likely assisted by water molecule in solution acting as a catalyst. | 0 | Organic Chemistry |
This category groups pages related to microRNA, which is cellular ribonucleic acid (RNA) that is often involved in gene regulation. | 1 | Biochemistry |
STAT1 has been shown to interact with:
* BRCA1,
* C-jun,
* CD117,
* CREB-binding protein,
* Calcitriol receptor,
* Epidermal growth factor receptor,
* Fanconi anemia, complementation group C,
* GNB2L1,
* IFNAR2,
* IRF1,
* ISGF3G
* Interleukin 27 receptor, alpha subunit,
* MCM5,
* Mammalian target of rapamycin,
* PIAS1,
* PRKCD,
* PTK2,
* Protein kinase R,
* STAT2,
* STAT3,
* Src, and
* TRADD. | 1 | Biochemistry |
By modeling reactions as Langevin motion along a one dimensional reaction coordinate, Hendrik Kramers was able to derive a relationship between the shape of the potential energy surface along the reaction coordinate and the transition rates of the system. The formulation relies on approximating the potential energy landscape as a series of harmonic wells. In a two state system, there will be three wells; a well for state A, an upside-down well representing the potential energy barrier, and a well for state B.
In the overdamped (or "diffusive") regime, the transition rate from state A to B is related to the resonant frequency of the wells via
where is the frequency of the well for state A, is the frequency of the barrier well, is the viscous damping, is the energy of the top of the barrier, is the energy of bottom of the well for state A, and is the temperature of the system times the Boltzmann constant.
For general damping (overdamped or underdamped), there is a similar formula. | 7 | Physical Chemistry |
Homoepitaxy is a kind of epitaxy performed with only one material, in which a crystalline film is grown on a substrate or film of the same material. This technology is often used to grow a more pure film than the substrate and to fabricate layers with different doping levels. In academic literature, homoepitaxy is often abbreviated to "homoepi".
Homotopotaxy is a process similar to homoepitaxy except that the thin-film growth is not limited to two-dimensional growth. Here the substrate is the thin-film material.
Heteroepitaxy is a kind of epitaxy performed with materials that are different from each other. In heteroepitaxy, a crystalline film grows on a crystalline substrate or film of a different material. This technology is often used to grow crystalline films of materials for which crystals cannot otherwise be obtained and to fabricate integrated crystalline layers of different materials. Examples include silicon on sapphire, gallium nitride (GaN) on sapphire, aluminium gallium indium phosphide (AlGaInP) on gallium arsenide (GaAs) or diamond or iridium, and graphene on hexagonal boron nitride (hBN).
Heteroepitaxy occurs when a film of different composition and/or crystalline films grown on a substrate. In this case, the amount of strain in the film is determined by the lattice mismatch Ԑ:
Where and are the lattice constants of the film and the substrate. The film and substrate could have similar lattice spacings but also different thermal expansion coefficients. If a film is grown at a high temperature, it can experience large strains upon cooling to room temperature. In reality, is necessary for obtaining epitaxy. If is larger than that, the film experiences a volumetric strain that builds with each layer until a critical thickness. With increased thickness, the elastic strain in the film is relieved by the formation of dislocations, which can become scattering centers that damage the quality of the structure. Heteroepitaxy is commonly used to create so-called bandgap systems thanks to the additional energy caused by de deformation. A very popular system with great potential for microelectronic applications is that of Si–Ge.
Heterotopotaxy is a process similar to heteroepitaxy except that thin-film growth is not limited to two-dimensional growth; the substrate is similar only in structure to the thin-film material.
Pendeo-epitaxy is a process in which the heteroepitaxial film is growing vertically and laterally simultaneously.
In 2D crystal heterostructure, graphene nanoribbons embedded in hexagonal boron nitride give an example of pendeo-epitaxy.
Grain-to-grain epitaxy involves epitaxial growth between the grains of a multicrystalline epitaxial and seed layer. This can usually occur when the seed layer only has an out-of-plane texture but no in-plane texture. In such a case, the seed layer consists of grains with different in-plane textures. The epitaxial overlayer then creates specific textures along each grain of the seed layer, due to lattice matching. This kind of epitaxial growth doesn't involve single-crystal films.
Epitaxy is used in silicon-based manufacturing processes for bipolar junction transistors (BJTs) and modern complementary metal–oxide–semiconductors (CMOS), but it is particularly important for compound semiconductors such as gallium arsenide. Manufacturing issues include control of the amount and uniformity of the depositions resistivity and thickness, the cleanliness and purity of the surface and the chamber atmosphere, the prevention of the typically much more highly doped substrate wafers diffusion of dopant to the new layers, imperfections of the growth process, and protecting the surfaces during manufacture and handling. | 3 | Analytical Chemistry |
Alkaliphiles maintain cytosolic acidification through both passive and active means. In passive acidification, it has been proposed that cell walls contain acidic polymers composed of residues such as galacturonic acid, gluconic acid, glutamic acid, aspartic acid, and phosphoric acid. Together, these residues form an acidic matrix that helps protect the plasma membrane from alkaline conditions by preventing the entry of hydroxide ions, and allowing for the uptake of sodium and hydronium ions. In addition, the peptidoglycan in alkaliphilic B. subtilis has been observed to contain higher levels of hexosamines and amino acids as compared to its neutrophilic counterpart. When alkaliphiles lose these acidic residues in the form of induced mutations, it has been shown that their ability to grow in alkaline conditions is severely hindered. However, it is generally agreed upon that passive methods of cytosolic acidification are not sufficient to maintain an internal pH 2-2.3 levels below that of external pH; there must also be active forms of acidification. The most characterized method of active acidification is in the form of Na/H antiporters. In this model, H ions are first extruded through the electron transport chain in respiring cells and to some extent through an ATPase in fermentative cells. This proton extrusion establishes a proton gradient that drives electrogenic antiporters—which drive intracellular Na out of the cell in exchange for a greater number of H ions, leading to the net accumulation of internal protons. This proton accumulation leads to a lowering of cytosolic pH. The expelled Na can be used for solute symport, which are necessary for cellular processes. It has been noted that Na/H antiport is required for alkaliphilic growth, whereas either K/H antiporters or Na/H antiporters can be utilized by neutrophilic bacteria. If Na/H antiporters are disabled through mutation or another means, the bacteria are rendered neutrophilic. The sodium required for this antiport system is the reason some alkaliphiles can only grow in saline environments. | 1 | Biochemistry |
The key intermediate in methylotrophic metabolism is formaldehyde, which can be diverted to either assimilatory or dissimilatory pathways. Methylotrophs produce formaldehyde through oxidation of methanol and/or methane. Methane oxidation requires the enzyme methane monooxygenase (MMO). Methylotrophs with this enzyme are given the name methanotrophs. The oxidation of methane (or methanol) can be assimilatory or dissimilatory in nature (see figure). If dissimilatory, the formaldehyde intermediate is oxidized completely into to produce reductant and energy. If assimilatory, the formaldehyde intermediate is used to synthesize a 3-Carbon () compound for the production of biomass. Many methylotrophs use multi-carbon compounds for anabolism, thus limiting their use of formaldehyde to dissimilatory processes, however methanotrophs are generally limited to only metabolism. | 0 | Organic Chemistry |
The National Science Foundation's (NSF) Ocean Observatories Initiative (OOI) [http://oceanobservatories.org/infrastructure/ooi-station-map/regional-scale-nodes/ Regional Scale Nodes] (RSN) component is an electro-optically cabled underwater observatory that directly connects to the global Internet. It is the largest cable-linked seabed observatory in the world, and also the first of its kind in the United States.
Located on the southern part of the Juan de Fuca plate, off the coast of Washington and Oregon, it is the first ocean observatory to span a tectonic plate.
RSN utilizes several high-power, high-bandwidth sub-sea terminals called primary nodes which are linked together by fiber-optic cable and provide support to oceanographic sensors at key [http://www.interactiveoceans.washington.edu/story/V14_Science locations].
Upon completion of the network in 2014, RSN will cover a distance of over 900 kilometers at depths of up to 3000 meters. Implementation of the OOI Regional Scale Nodes is led by the University of Washington's (UW) [http://www.ocean.washington.edu School of Oceanography], the [http://www.apl.washington.edu UW Applied Physics Laboratory], and [http://www.l-3mps.com/maripro/index.aspx L-3 MariPro].
Live RSN data from >100 seafloor and water column instruments will be made available live on the Internet. This will allow both scientists and the general public to study long-term changes in ocean systems over the next 25 years.
Construction of RSN will be completed in 2014. Efforts are substantially aided by the crews of [http://www.ropos.com/ ROPOS (Remotely Operated Platform for Observation Sciences]. The [http://www.interactiveoceans.washington.edu/story/VISIONS_14 83-day VISIONS ’14 expedition] aboard the 274-foot global-class R/V Thomas G. Thompson is responsible for the observatory's final implementation. | 9 | Geochemistry |
STAT6-mediated signaling pathway is required for the development of T-helper type 2 (Th2) cells and Th2 immune response. Expression of Th2 cytokines, including IL-4, IL-13, and IL-5, was reduced in STAT6-deficient mice. STAT 6 protein is crucial in IL4 mediated biological responses. It was found that STAT6 induce the expression of BCL2L1/BCL-X(L), which is responsible for the anti-apoptotic activity of IL4. IL-4 stimulates the phosphorylation of IL-4 receptor, which recruits cytosolic STAT6 by its SH2 domain and STAT6 is phosphorylated on tyrosine 641 (Y641) by JAK1, which results in the dimerization and nuclear translocation of STAT6 to activate target genes. Knockout studies in mice suggested the roles of this gene in differentiation of T helper 2 (Th2), expression of cell surface markers, and class switch of immunoglobulins.
Activation of STAT6 signaling pathway is necessary in macrophage function, and is required for the M2 subtype activation of macrophages. STAT6 protein also regulates other transcription factor as Gata3, which is important regulator of Th2 differentiation. STAT6 is also required for the development of IL-9-secreting T cells.
STAT6 also plays a critical role in Th2 lung inflammatory responses including clearance of parasitic infections and in the pathogenesis of asthma. Th2-cell derived cytokines as IL-4 and IL-13 induce the production of IgE which is a major mediator in allergic response. Association studies searching for relation of polymorphisms in STAT6 with IgE level or asthma discovered a few polymorphisms significantly associated with examined traits. Only two polymorphisms showed repeatedly significant clinical association and/or functional effect on STAT6 function (GT repeats in exon 1 and rs324011 polymorphism in intron 2). | 1 | Biochemistry |
As an example of a thermodynamic process involving a photon gas, consider a cylinder with a movable piston. The interior walls of the cylinder are "black" in order that the temperature of the photons can be maintained at a particular temperature. This means that the space inside the cylinder will contain a blackbody-distributed photon gas. Unlike a massive gas, this gas will exist without the photons being introduced from the outside – the walls will provide the photons for the gas. Suppose the piston is pushed all the way into the cylinder so that there is an extremely small volume. The photon gas inside the volume will press against the piston, moving it outward, and in order for the transformation to be isothermic, a counter force of almost the same value will have to be applied to the piston so that the motion of the piston is very slow. This force will be equal to the pressure times the cross sectional area (A ) of the piston. This process can be continued at a constant temperature until the photon gas is at a volume V . Integrating the force over the distance (x ) traveled yields the total work done to create this photon gas at this volume
where the relationship V = Ax has been used. Defining
The pressure is
Integrating, the work done is just
The amount of heat that must be added in order to create the gas is
where H is the enthalpy at the end of the transformation. It is seen that the enthalpy is the amount of energy needed to create the photon gas. | 7 | Physical Chemistry |
Methanosaeta harundinacea 6Ac, a methanogenic archaeon, produces carboxylated acyl homoserine lactone compounds that facilitate the transition from growth as short cells to growth as filaments. | 1 | Biochemistry |
Synthesis of marmesin has been successfully conducted in the laboratory on multiple occasions. One way of doing so is by a strategy based on the palladium-catalyzed intramolecular coupling reaction. This reaction would construct the dihydropyran ring and synthesize the compound from the intermediate (-)-peucedanol. The key step in the overall synthesis uses catalytic asymmetric epoxidation of an enone. | 1 | Biochemistry |
mTECs are not only capable to present TRAs as efficient APCs. They are also potent in production of these TRAs via unique process called promiscuous gene expression (PGE) and might serve as their reservoir. | 1 | Biochemistry |
Supercritical carbon dioxide is used to enhance oil recovery in mature oil fields. At the same time, there is the possibility of using "clean coal technology" to combine enhanced recovery methods with carbon sequestration. The CO is separated from other flue gases, compressed to the supercritical state, and injected into geological storage, possibly into existing oil fields to improve yields.
At present, only schemes isolating fossil CO from natural gas actually use carbon storage, (e.g., Sleipner gas field), but there are many plans for future CCS schemes involving pre- or post- combustion CO. There is also the possibility to reduce the amount of CO in the atmosphere by using biomass to generate power and sequestering the CO produced. | 7 | Physical Chemistry |
Inhibition of PSII is caused by singlet oxygen produced either by weakly coupled chlorophyll molecules or by cytochromes or iron–sulfur centers. | 5 | Photochemistry |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.