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A scleroscope is a device used to measure rebound hardness. It consists of a steel ball dropped from a fixed height. The device was invented in 1907. As an improvement on this rough method, the Leeb Rebound Hardness Test, invented in the 1970s, uses the ratio of impact and rebound velocities (as measured by a magnet... | 8 | Metallurgy |
People can be exposed to bitumen in the workplace by breathing in fumes or skin absorption. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit of 5 mg/m over a 15-minute period.
Bitumen is basically an inert material that must be heated or diluted to a point where it ... | 7 | Physical Chemistry |
Additional evidence supporting the concept of an RNA world has resulted from research on viroids, the first representatives of a novel domain of "subviral pathogens".
Viroids infect plants, where most are pathogens, and consist of short stretches of highly complementary, circular, single-stranded and non-coding RNA wit... | 9 | Geochemistry |
The development of fluorometers allowed chlorophyll fluorescence analysis to become a common method in plant research. Chlorophyll fluorescence analysis has been revolutionized by the invention of the Pulse-Amplitude-Modulation (PAM) technique and availability of the first commercial modulated chlorophyll fluorometer ... | 5 | Photochemistry |
Sequencing of nearly an entire human genome was first accomplished in 2000 partly through the use of shotgun sequencing technology. While full genome shotgun sequencing for small (4000–7000 base pair) genomes was already in use in 1979, broader application benefited from pairwise end sequencing, known colloquially as d... | 1 | Biochemistry |
Human activities have also dramatically altered the global nitrogen cycle via production of nitrogenous gases, associated with the global atmospheric nitrogen pollution. There are multiple sources of atmospheric reactive nitrogen (Nr) fluxes. Agricultural sources of reactive nitrogen can produce atmospheric emission o... | 1 | Biochemistry |
The coordination of alkynes to transition metals is similar to that of alkenes. The bonding is described by the Dewar–Chatt–Duncanson model. Upon complexation the C-C bond elongates and the alkynyl carbon bends away from 180º. For example, in the phenylpropyne complex Pt(PPh)(MeCPh), the C-C distance is 1.277(25) vs 1.... | 0 | Organic Chemistry |
Gerel Ochir was born in Moscow on 17 July 1941. She gained an interest in geology at the age of 10 after her mother gave her a book on geology by Russian geochemist Alexander Fersman. She graduated from secondary school in Ulaanbaatar in 1958.
From 1959, Ochir attended Charles University in Prague. She earned a bachelo... | 9 | Geochemistry |
RMR is regularly used in ecology to study the response of individuals to changes in environmental conditions.
Parasites by definition have a negative impact on their hosts and it is thus expected that there might be effects on host RMR. Varying effects of parasite infection on host RMR have been found. Most studies ind... | 1 | Biochemistry |
Oxidative carbonylation is an alternative to phosgenation. The advantage is the avoidance of phosgene. Using copper catalysts, dimethylcarbonate is prepared in this way:
: 2 MeOH + CO + 1/2 O → MeOC(O)OMe + HO
Diphenyl carbonate is also prepared similarly, but using palladium catalysts. The Pd-catalyzed process req... | 0 | Organic Chemistry |
Genome-wide CRISPR-Cas9 knockout screens aim to elucidate the relationship between genotype and phenotype by ablating gene expression on a genome-wide scale and studying the resulting phenotypic alterations. The approach utilises the CRISPR-Cas9 gene editing system, coupled with libraries of single guide RNAs (sgRNAs),... | 1 | Biochemistry |
During the formation of a crystalline structure, different impurities, irregularities, and other defects can form. These imperfections can form through deformation of the solid, rapid cooling, or high energy radiation. Types of defects include point defects, line defects, as well as edge dislocation. | 1 | Biochemistry |
Allyl thiocyanate isomerizes to the isothiocyanate:
Isothiocyanates can be prepared by degradation of dithiocarbamate salts, e.g. induced with lead nitrate.
A related method is tosyl chloride-mediated decomposition of dithiocarbamate salts.
Isothiocyanates may also be accessed by the fragmentation reactions of 1,4,2-ox... | 0 | Organic Chemistry |
Rigid unit modes (RUMs) represent a class of lattice vibrations or phonons that exist in network materials such as quartz, cristobalite or zirconium tungstate. Network materials can be described as three-dimensional networks of polyhedral groups of atoms such as SiO tetrahedra or TiO octahedra. A RUM is a lattice vibra... | 3 | Analytical Chemistry |
* van der Waals Prize 2021 (awarded in 2022 by the 2nd International Conference on Noncovalent Interactions, ICNI-2022)
* RSC-SCI Award Lectureship in the Chemical Sciences (awarded in 2010 by Royal Society of Chemistry/Società Chimica Italiana)
* Intermolecular Interactions and Structural Aspects in Organic Chemistry... | 0 | Organic Chemistry |
Many radical processes involve chain reactions or chain propagation with disproportionation and recombination occurring in the terminal step of the reaction. Terminating chain propagation is often most significant during polymerization as the desired chain propagation cannot take place if disproportionation and recombi... | 0 | Organic Chemistry |
UNECE recognizes several rivers that cross international borders which flow into the Caspian Sea.
These are: | 2 | Environmental Chemistry |
HCN4 is the main isoform expressed in the sinoatrial node, but low levels of HCN1 and HCN2 have also been reported.
The current through HCN channels, called the pacemaker current (I), plays a key role in the generation and modulation of cardiac rhythmicity, as they are responsible for the spontaneous depolarization in ... | 1 | Biochemistry |
Stopped-flow spectrometry allows chemical kinetics of fast reactions (with half times of the order of milliseconds) to be studied in solution. It was first used primarily to study enzyme-catalyzed reactions. Then the stopped-flow rapidly found its place in almost all biochemistry, biophysics, and chemistry laboratorie... | 7 | Physical Chemistry |
The Van t Hoff equation relates the change in the equilibrium constant, , of a chemical reaction to the change in temperature, T, given the standard enthalpy change, , for the process. The subscript means "reaction" and the superscript means "standard". It was proposed by Dutch chemist Jacobus Henricus van t Hoff in ... | 7 | Physical Chemistry |
Polyclonal B cell response is a natural mode of immune response exhibited by the adaptive immune system of mammals. It ensures that a single antigen is recognized and attacked through its overlapping parts, called epitopes, by multiple clones of B cell.
In the course of normal immune response, parts of pathogens (e.g. ... | 1 | Biochemistry |
The trihexagonal tiling exists in a sequence of symmetries of quasiregular tilings with vertex configurations (3.n), progressing from tilings of the sphere to the Euclidean plane and into the hyperbolic plane. With orbifold notation symmetry of *n32 all of these tilings are wythoff construction within a fundamental dom... | 3 | Analytical Chemistry |
Unlike other endonucleases, the MmeI (type IIS) and EcoP15I (type III) restriction endonucleases cut downstream of their target binding sites. MmeI cuts 18/20 base pairs downstream and EcoP15I cuts 25/27 base pairs downstream. As these restriction enzymes bind at their target sequences located in the adaptors, they cut... | 1 | Biochemistry |
Coupling reactions are routinely employed in the preparation of pharmaceuticals. Conjugated polymers are prepared using this technology as well. | 0 | Organic Chemistry |
The water-repelling liquid is applied:
* To provide the surface of materials with excellent water resistance properties - the surface does not absorb water;
* To make the material frost- and corrosion resistant;
* To reduce the pollution of surface;
In addition, the treated surface does not change its appearance, maint... | 6 | Supramolecular Chemistry |
In 1955, biologists Britton Chance and G. R. Williams were the first to propose the idea that respiratory enzymes assemble into larger complexes, although the fluid state model remained the standard. However, as early as 1985, researchers had begun isolating complex III/complex IV supercomplexes from bacteria and yeast... | 1 | Biochemistry |
Solvents with a dielectric constant (more accurately, relative static permittivity) greater than 15 (i.e. polar or polarizable) can be further divided into protic and aprotic. Protic solvents, such as water, solvate anions (negatively charged solutes) strongly via hydrogen bonding. Polar aprotic solvents, such as aceto... | 2 | Environmental Chemistry |
Some sucrose esters, such as sucrose distearate, sucrose dilaurate, sucrose palmitate, etc. are added in cosmetics products as an emulsifier. Some have a function in skin conditioning and emollient. Cosmetics products that might have sucrose esters as an ingredient includes eyelash products, hair treatments, oil gels, ... | 0 | Organic Chemistry |
Solid diazonium halides are often dangerously explosive, and fatalities and injuries have been reported.
The nature of the anions affects stability of the salt. Arenediazonium perchlorates, such as nitrobenzenediazonium perchlorate, have been used to initiate explosives. | 0 | Organic Chemistry |
The RNA-editing system seen in the animal may have evolved from mononucleotide deaminases, which have led to larger gene families that include the apobec-1 and adar genes. These genes share close identity with the bacterial deaminases involved in nucleotide metabolism. The adenosine deaminase of E. coli cannot deaminat... | 1 | Biochemistry |
Microscopically, liquids consist of a dense, disordered packing of molecules. This contrasts with the other two common phases of matter, gases and solids. Although gases are disordered, the molecules are well-separated in space and interact primarily through molecule-molecule collisions. Conversely, although the molecu... | 7 | Physical Chemistry |
The charge modulation spectroscopy signal can be defined as the differential transmission divided by the total transmission . By modulating the mobile carriers, an increase transmission and decrease transmission features could be both observed. The former relates to the bleaching and the latter to the charge absorpt... | 7 | Physical Chemistry |
Polar liquids have a tendency to be more viscous than nonpolar liquids. For example, nonpolar hexane is much less viscous than polar water. However, molecule size is a much stronger factor on viscosity than polarity, where compounds with larger molecules are more viscous than compounds with smaller molecules. Thus, wat... | 7 | Physical Chemistry |
The photocytes of Renilla köllikeri were found to have a diameter of eight to ten micrometers. The mitochondria of the photocytes were found to be very large with abnormally organized cristae surrounding the nucleus of the cell. The rough endoplasmic reticulum of the photocytes were found to exist close to the cell mem... | 1 | Biochemistry |
The empirical formula for benzene was long known, but its highly polyunsaturated structure, with just one hydrogen atom for each carbon atom, was challenging to determine. Archibald Scott Couper in 1858 and Johann Josef Loschmidt in 1861 suggested possible structures that contained multiple double bonds or multiple rin... | 2 | Environmental Chemistry |
Increasing the yield of succinate from mixed acid fermentation was first done by overexpressing the enzyme PEP carboxylase. This produced a succinate yield that was approximately 3 times greater than normal. Several experiments using a similar approach have followed.
Alternative approaches have altered the redox and AT... | 1 | Biochemistry |
Dissimilatory nitrate reduction to ammonium is similar to the process of denitrification, though NO is reduced farther to NH rather than to N, transferring eight electrons. Both denitrifiers and nitrate ammonifiers are competing for NO in the environment. Despite the redox potential of dissimilatory nitrate reduction t... | 1 | Biochemistry |
Phenoxymethylpenicillin is usually well tolerated but may occasionally cause transient nausea, vomiting, epigastric distress, diarrhea, constipation, acidic smell to urine and black hairy tongue. A previous hypersensitivity reaction to any penicillin is a contraindication. | 4 | Stereochemistry |
Carpanone is a naturally occurring lignan-type natural product most widely known for the remarkably complex way nature prepares it, and the similarly remarkable success that an early chemistry group, that of Orville L. Chapman, had at mimicking natures pathway. Carpanone is an organic compound first isolated from the c... | 0 | Organic Chemistry |
(LAP-A), a product of the octadecanoid pathway in some solanaceous plants, has been shown by Fowler et al. to have a regulatory role in the late wound response of tomato. Experiments were conducted using three genotypes of tomato plants: wildtype (WT), (LapA-SI) plants that were silenced for LAP-A, and LapA-OX that con... | 1 | Biochemistry |
Modern-day boilers, such as those in coal-fired power stations, are still fitted with economizers which are descendants of Green's original design. In this context they are often referred to as feedwater heaters and heat the condensate from turbines before it is pumped to the boilers.
Economizers are commonly used as ... | 7 | Physical Chemistry |
The Sharpless epoxidation, developed by K. Barry Sharpless in 1980, has been utilized for the kinetic resolution of a racemic mixture of allylic alcohols. While extremely effective at resolving a number of allylic alcohols, this method has a number of drawbacks. Reaction times can run as long as 6 days, and the catalys... | 4 | Stereochemistry |
The so-called carbamate insecticides feature the carbamate ester functional group. Included in this group are aldicarb (Temik), carbofuran (Furadan), carbaryl (Sevin), ethienocarb, fenobucarb, oxamyl, and methomyl. These insecticides kill insects by reversibly inactivating the enzyme acetylcholinesterase (AChE inhibiti... | 0 | Organic Chemistry |
Planar Flow Casting (PFC) is a commonly used melt spinning process for the industrial fabrication of wide metallic glass sheets. In this process, the primary modification is that a much wider nozzle is used to eject the melt from the crucible. As a result, the melt puddle covers a larger area of the drum, which in turn... | 8 | Metallurgy |
Annual Review of Physical Chemistry is a peer-reviewed scientific journal published by Annual Reviews. It covers all topics pertaining to physical chemistry. The editors are Todd J. Martínez (Stanford University) and Anne McCoy (University of Washington). As of 2023, Annual Review of Physical Chemistry is being publ... | 7 | Physical Chemistry |
His lectures frequently lasted for three or four hours. His longest known lecture defined the unit of time known as the "Woodward", after which his other lectures were deemed to be so many "milli-Woodwards" long. In many of these, he eschewed the use of slides and drew structures by using multicolored chalk. Typically,... | 4 | Stereochemistry |
Four members of 2A peptides family are frequently used in life science research. They are P2A, E2A, F2A, and T2A. F2A is derived from foot-and-mouth disease virus 18; E2A is derived from equine rhinitis A virus; P2A is derived from porcine teschovirus-1 2A; T2A is derived from thosea asigna virus 2A.
The following ta... | 1 | Biochemistry |
A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input. The name is from the Greek roots mono-, "single", and chroma, "colour", and the Latin suffix -ator, denoting an agent. | 7 | Physical Chemistry |
Late transition metals from groups 10, 11, and 12 when placed at the anomeric carbon show strong axial preferences. This phenomenon termed as the metallo-anomeric effect originates from stabilizing hyperconjugative interactions between oxygen or other heteroatoms with lone pairs and C-M anti-bonding orbitals that act a... | 7 | Physical Chemistry |
Trifluoromethylsulfur pentafluoride, CFSF, is a rarely used industrial greenhouse gas. It was first identified in the atmosphere in 2000. Trifluoromethylsulfur pentafluoride is considered to be one of the several "super-greenhouse gases". | 2 | Environmental Chemistry |
The hexahydrate consists of octahedral cation centers and chloride anions () as counterions. Hydrogen bonds link the cation and anions.
The hydrated form of aluminium chloride has an octahedral molecular geometry, with the central aluminium ion surrounded by six water ligand molecules. Being coordinatively saturated, ... | 0 | Organic Chemistry |
Ethyl bromoacetate is listed by the World Health Organization as a riot control agent, and was first employed for that purpose by French police in 1912. The French army used rifle grenades grenades lacrymogènes filled with this gas against the Germans beginning in August 1914, but the weapons were largely ineffective, ... | 0 | Organic Chemistry |
Crystalline structure is the composition of ions, atoms, and molecules that are held together and ordered in a 3D shape. The main difference between a crystalline structure and an amorphous structure is the order of the components. Crystalline has the highest level of order possible in the material where amorphous stru... | 1 | Biochemistry |
At equilibrium, the sum of the chemical potentials of the reactants is equal to the sum of the chemical potentials of the products. The Gibbs free energy change for the reactions, ΔG, is equal to the difference between these sums and therefore, at equilibrium, is equal to zero. Thus, for an equilibrium such as
Substitu... | 7 | Physical Chemistry |
Like the photo-oxidation method, UV light is the oxidizer but the oxidation power of the reaction is magnified by the addition of a chemical oxidizer, which is usually a persulfate compound. The mechanisms of the reactions are as follows:
Free radical oxidants formed:
Excitation of organics:
Oxidation of organics:
The ... | 3 | Analytical Chemistry |
As the slag becomes enriched with iron oxide during the reaction in air, it becomes basic and then combines with the siliceous refractory lining, which is very acidic. A basic refractory lining would not react and would therefore lower the cost of production. The adoption of a lining inspired by one developed by Sidney... | 8 | Metallurgy |
Previously called "ideal ATM" and "polarization-varying ATM," stationary sample ATM (SSATM) involves rotation of the linearly polarized state of the THz beam in a time-domain spectroscopy (TDS) configuration parallel to the interrogated material sample. In a SSATM configuration, the THz beam polarization is rotated thr... | 7 | Physical Chemistry |
As early as 1976 a short-term, relatively small, dead zone off the coasts of New York and New Jersey cost commercial and recreational fisheries over $500 million. In 1998 a HAB in Hong Kong killed over $10 million in high-value fish.
In 2009, the economic impact for the state of Washington's coastal counties dependent ... | 3 | Analytical Chemistry |
After the first bond is synthesized, the RNA polymerase must clear the promoter. During this time, there is a tendency to release the RNA transcript and produce truncated transcripts. This is called abortive initiation and is common for both eukaryotes and prokaryotes. Abortive initiation continues to occur until the... | 1 | Biochemistry |
Polymerized ionic liquids, poly(ionic liquid)s or polymeric ionic liquids, all abbreviated as PIL is the polymeric form of ionic liquids. They have half of the ionicity of ionic liquids since one ion is fixed as the polymer moiety to form a polymeric chain. PILs have a similar range of applications, comparable with tho... | 7 | Physical Chemistry |
Atmospheric carbon dioxide has risen from 280 to 409 ppm since the industrial revolution. This increase in carbon dioxide has led to a 0.1 decrease in pH, and it could decrease by 0.5 by 2100. When carbon dioxide meets seawater, it forms carbonic acid; the molecules dissociate into hydrogen, bicarbonate, and carbonate,... | 9 | Geochemistry |
The equation describing the fluorescence as a function of time is particularly simple in another limit. If a large number of proteins bind to sites in a small volume such that there the fluorescence signal is dominated by the signal from bound proteins, and if this binding is all in a single state with an off rate k, t... | 1 | Biochemistry |
While the presence of any symmetry element within a ligand intended for asymmetric induction might appear counterintuitive, asymmetric induction only requires that the ligand be chiral (i.e. have no improper rotation axis). Asymmetry (i.e. absence of any symmetry elements) is not required. C symmetry improves the enant... | 4 | Stereochemistry |
Aqueous samples, lysed cells, or homogenised tissue are mixed with equal volumes of a phenol:chloroform mixture. This mixture is then centrifuged. Because the phenol:chloroform mixture is immiscible with water, the centrifuge will cause two distinct phases to form: an upper aqueous phase, and a lower organic phase. The... | 1 | Biochemistry |
Gamma helix (or γ-helix) is a type of secondary structure in proteins that has been predicted by Pauling, Corey, and Branson, but has never been observed in natural proteins. The hydrogen bond in this type of helix was predicted to be between N-H group of one amino acid and the C=O group of the amino acid six residues ... | 1 | Biochemistry |
For iron rust to occur the metal has to be in contact with oxygen and water. The chemical reactions for this process are relatively complex and not all of them are completely understood. It is believed the causes are the following:
Electron transfer (reduction-oxidation)
:One area on the surface of the metal acts as th... | 7 | Physical Chemistry |
In molecular biology, protein catabolism is the breakdown of proteins into smaller peptides and ultimately into amino acids. Protein catabolism is a key function of digestion process. Protein catabolism often begins with pepsin, which converts proteins into polypeptides. These polypeptides are then further degraded.... | 1 | Biochemistry |
For small-scale hydrogen production, RO is sometimes used to prevent formation of mineral deposits on the surface of electrodes. | 3 | Analytical Chemistry |
Solder bumping technology (the process of joining a chip to a substrate without shorting using solder) was first conceived and implemented by IBM in the early 1960s. Three versions of this type of solder joining were developed. The first was to embed copper balls in the solder bumps to provide a positive stand-off. ... | 7 | Physical Chemistry |
Genetic disorders are often an issue within captive populations due to the fact that the populations are usually established from a small number of founders. In large, outbreeding populations, the frequencies of most deleterious alleles are relatively low, but when a population undergoes a bottleneck during the foundi... | 1 | Biochemistry |
Thermodynamic scale differs from empirical scales in that it is absolute. It is based on the fundamental laws of thermodynamics or statistical mechanics instead of some arbitrary chosen working material. Besides it covers full range of temperature and has simple relation with microscopic quantities like the average kin... | 7 | Physical Chemistry |
Selective leaching can be used to produce powdered materials with extremely high surface area, such as Raney nickel and other heterogeneous catalysts. Selective leaching can be the pre-final stage of depletion gilding. | 8 | Metallurgy |
One method for synthesizing ynones is the acyl substitution reaction of an alkynyldimethylaluminum with an acyl chloride. An alkynyldimethylaluminum compound is the reaction product of trimethylaluminum and a terminal alkyne.
An alternative is the direct coupling of an acyl chloride with a terminal alkyne, using a copp... | 0 | Organic Chemistry |
Vitamin A deficiency is common in developing countries, especially in Sub-Saharan Africa and Southeast Asia. Deficiency can occur at any age, but is most common in pre-school-age children and pregnant women, the latter due to a need to transfer retinol to the fetus. The causes are low intake of retinol-containing, anim... | 1 | Biochemistry |
The construction of large-scale microalgae cultivation facilities would inevitably result in negative environmental impacts related to land use change, such as the destruction of existing natural habitats. Microalgae can also under certain conditions emit greenhouse gases, like methane or nitrous oxide, or foul-smellin... | 0 | Organic Chemistry |
A pigment termed molybdenum blue is recorded in 1844 as a mixture of molybdenum with "oxyde of tin or phosphate of lime". An alternative formulation involves "digesting" molybdenum sulfide with nitric acid to form molybdic acid, which is then mixed with tin filings and a little muriatic acid (HCl). This is evaporated ... | 7 | Physical Chemistry |
Precondition for the applicability of sensor-based ore sorting is the presence of liberation at the particle size of interest. Before entering into sensor-based ore sorting testing procedures there is the possibility to assess the degree of liberation through the inspection of drill cores, hand-counting and washability... | 3 | Analytical Chemistry |
Maternal overnutrition can have detrimental effects on the health of the offspring later in life. This area is less well studied and understood but some progress has been made in identifying specific genes that are affected. Studies have investigated hypermethylation of DNA and found it to be higher in obese mothers to... | 1 | Biochemistry |
Levels of phosphatidylethanols in blood are used as markers of previous alcohol consumption.
An increase of alcohol intake by ~20 g ethanol/day will raise the PEth 16:0/18:1 concentration by ~0.10 μmol/L, and vice versa if the alcohol consumption has decreased. However, it has been demonstrated that there can be signif... | 1 | Biochemistry |
Drinking water which has been chlorinated to kill microbes may contain trace levels of chlorine. The World Health Organization recommends an upper limit of 5 ppm.
Although low, 5 ppm is enough to slowly attack certain types of plastic, particularly when the water is heated, as it is for washing.
Polyethylene, polybutyl... | 7 | Physical Chemistry |
An organic compound is a chemical whose molecules contain carbon. Carbon is abundant in the Sun, stars, comets, and in the atmospheres of most planets. Organic compounds are relatively common in space, formed by "factories of complex molecular synthesis" which occur in molecular clouds and circumstellar envelopes, and ... | 9 | Geochemistry |
Recent work suggests that molecular recognition elements can be synthetically produced at the nano-scale, circumventing the need for naturally occurring molecular recognition elements for the development of sensing tools for small molecules. Bio-mimetic polymers such as molecular imprinted polymers and peptoids can be ... | 6 | Supramolecular Chemistry |
Plants under horticultural care in a constructed landscape, typically a botanic garden or arboreta. This technique is similar to a field gene bank in that plants are maintained in the ambient environment, but the collections are typically not as genetically diverse or extensive. These collections are susceptible to hyb... | 1 | Biochemistry |
Secondary standards are compounds with a concentration determined by a primary standard. Secondary standards do not satisfy the requirements for a primary standard. | 3 | Analytical Chemistry |
Coactivators are promising targets for drug therapies in the treatment of cancer, metabolic disorder, cardiovascular disease and type 2 diabetes, along with many other disorders. For example, the steroid receptor coactivator (SCR) NCOA3 is often overexpressed in breast cancer, so the development of an inhibitor molecul... | 1 | Biochemistry |
Ambident is a molecule or group that has two alternative and interacting reaction sites, to either of which a bond may be made during a reaction, in Chemistry. | 7 | Physical Chemistry |
E.coli are shown to be more sensitive to accumulations of guanosine tetraphosphate than guanosine pentaphosphate. A complete absence of (p)ppGpp causes multiple amino acid requirements, poor survival of aged cultures, aberrant cell division, morphology, and immotility, as well as being locked in a growth mode during e... | 1 | Biochemistry |
SELDI is often criticized for its reproducibility due to differences in the mass spectra obtained when using different batches of chip surfaces. While the method has been successful with analyzing low molecular weight proteins, consistent results have not been obtained when analyzing high molecular weight proteins. The... | 1 | Biochemistry |
If we attempt to build a densely packed collection of spheres, we will be tempted to always place the next sphere in a hollow between three packed spheres. If five spheres are assembled in this way, they will be consistent with one of the regularly packed arrangements described above. However, the sixth sphere placed i... | 3 | Analytical Chemistry |
Each dislocation is associated with a strain field which contributes some small but finite amount to the materials stored energy. When the temperature is increased - typically below one-third of the absolute melting point - dislocations become mobile and are able to glide, cross-slip and climb. If two dislocations of o... | 8 | Metallurgy |
Pseudoknots are common structural motifs found in RNA. They are formed by two nested stem-loops such that the stem of one structure is formed from the loop of the other. There are multiple folding topologies among pseudoknots and great variation in loop lengths, making them a structurally diverse group.
Inverted repe... | 1 | Biochemistry |
The density of saltwater depends on the dissolved salt content as well as the temperature. Ice still floats in the oceans, otherwise, they would freeze from the bottom up. However, the salt content of oceans lowers the freezing point by about 1.9 °C (due to freezing-point depression of a solvent containing a solute) an... | 2 | Environmental Chemistry |
In 1980, Staden wrote: In order to make it easier to talk about our data gained by the shotgun method of sequencing we have invented the word "contig". A contig is a set of gel readings that are related to one another by overlap of their sequences. All gel readings belong to one and only one contig, and each contig co... | 1 | Biochemistry |
cAMP is a signaling molecule important for a variety of cellular functions. cAMP exerts its effects by activating the cAMP-dependent protein kinase A (PKA), which transduces the signal through phosphorylation of different target proteins. The inactive holoenzyme of PKA is a tetramer composed of two regulatory and two c... | 1 | Biochemistry |
Many kinds of diketones are known, some with unusual properties. The simplest is diacetyl , once used as butter-flavoring in popcorn. Acetylacetone (pentane-2,4-dione) is virtually a misnomer (inappropriate name) because this species exists mainly as the monoenol . Its enolate is a common ligand in coordination chemist... | 0 | Organic Chemistry |
Dextroamphetamine is the active metabolite of the prodrug lisdexamfetamine (L-lysine-dextroamphetamine), available by the brand name Vyvanse (Elvanse in the European market) (Venvanse in the Brazil market) (lisdexamfetamine dimesylate). Dextroamphetamine is liberated from lisdexamfetamine enzymatically following contac... | 4 | Stereochemistry |
For typical three-dimensional metals, the temperature-dependence of the electrical resistivity ρ(T) due to the scattering of electrons by acoustic phonons changes from a high-temperature regime in which ρ ∝ T to a low-temperature regime in which ρ ∝ T at a characteristic temperature known as the Debye temperature. For ... | 7 | Physical Chemistry |
Bees can use trail pheromones to mark food sources and the entrance of their hives. Oftentimes, when finding a source, bees will mark that exact location as well as secreting pheromones along the flight back to their hives. Employment of trail pheromones is extensively studied in honey bees and stingless bees, for both... | 1 | Biochemistry |
The E1 subunit, called the pyruvate dehydrogenase subunit, is either a homodimer (comprising two “ɑ” chains, e.g. in Escherichia coli) or a heterotetramer of two different chains (two “ɑ” and two “ꞵ” chains). A magnesium ion forms a 4-coordinate complex with three, polar amino acid residues (Asp, Asn, and Tyr) located... | 1 | Biochemistry |
The retinoic acid receptor (RAR) is a type of nuclear receptor which can also act as a ligand-activated transcription factor that is activated by both all-trans retinoic acid and 9-cis retinoic acid, retinoid active derivatives of Vitamin A. They are typically found within the nucleus. There are three retinoic acid re... | 1 | Biochemistry |
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