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To stop the corrosion from continuing the object just needs to be aired out to remove any moisture and allow the normal layer of protection to form. Washing and a wire brush will remove most of the corrosion. For complete removal, 10% acetic acid or a mixture of polishing chalk and 20–40% NaOH can be used. Both require...
8
Metallurgy
Spiral separators of the wet type, also called spiral concentrators, are devices to separate solid components in a slurry, based upon a combination of the solid particle density as well as the particle's hydrodynamic properties (e.g. drag). The device consists of a tower, around which is wound a sluice, from which slot...
3
Analytical Chemistry
SH2 domains are not present in yeast and appear at the boundary between protozoa and animalia in organisms such as the social amoeba Dictyostelium discoideum. A detailed bioinformatic examination of SH2 domains of human and mouse reveals 120 SH2 domains contained within 115 proteins encoded by the human genome, represe...
1
Biochemistry
Crystallographic directions are lines linking nodes (atoms, ions or molecules) of a crystal. Similarly, crystallographic planes are planes linking nodes. Some directions and planes have a higher density of nodes; these dense planes have an influence on the behavior of the crystal: *optical properties: in condensed matt...
3
Analytical Chemistry
A number of organism-specific transcriptome databases have been constructed and annotated to aid in the identification of genes that are differentially expressed in distinct cell populations. RNA-seq is emerging (2013) as the method of choice for measuring transcriptomes of organisms, though the older technique of DNA ...
1
Biochemistry
A fourth group has also been discovered and members have three amino acids between the two cysteines and is termed CXC chemokine (or d-chemokines). The only CXC chemokine discovered to date is called fractalkine (or CXCL1). It is both secreted and tethered to the surface of the cell that expresses it, thereby serving a...
1
Biochemistry
In fluid mechanics, dewetting is one of the processes that can occur at a solid–liquid, solid–solid or liquid–liquid interface. Generally, dewetting describes the process of retraction of a fluid from a non-wettable surface it was forced to cover. The opposite process—spreading of a liquid on a substrate—is called wet...
7
Physical Chemistry
From the structural perspective, haloalkanes can be classified according to the connectivity of the carbon atom to which the halogen is attached. In primary (1°) haloalkanes, the carbon that carries the halogen atom is only attached to one other alkyl group. An example is chloroethane (). In secondary (2°) haloalkanes,...
0
Organic Chemistry
Tumor angiogenesis rely on interactions between endothelial vascular growth factors which can all activate the PI3K/AKT/mTOR in endothelial cells, pericytes, or cancer cells. Example of these growth factors are angiopoietin 1 (ANG1), ANG 2, basic fibroblast growth factor (bFGF), ephrin-B2, vascular endothelial growth f...
1
Biochemistry
Small interfering (siRNA) are short, 19-23 base-pair (with a 3 overhang of two nucleotides), double-stranded pieces of RNA that participate in the RNA-induced silencing complex (RISC) for gene silencing. Specifically, siRNA is bound by the RISC complex where it is unwound using ATP hydrolysis. It is then used as a guid...
1
Biochemistry
In atomic, molecular and optical physics, the Araki–Sucher correction is a leading-order correction to the energy levels of atoms and molecules due to effects of quantum electrodynamics (QED). It is named after Huzihiro Araki and Joseph Sucher, who first calculated it for the helium atom in 1957. The method is based on...
7
Physical Chemistry
*Arc discharge: this is a high power thermal discharge of very high temperature (≈10,000 K). It can be generated using various power supplies. It is commonly used in metallurgical processes. For example, it is used to smelt minerals containing AlO to produce aluminium. *Corona discharge: this is a non-thermal discharge...
7
Physical Chemistry
The contribution of each gas to the enhanced greenhouse effect is determined by the characteristics of that gas, its abundance, and any indirect effects it may cause. For example, the direct radiative effect of a mass of methane is about 84 times stronger than the same mass of carbon dioxide over a 20-year time frame. ...
2
Environmental Chemistry
Jaroslav Heyrovský () (December 20, 1890 – March 27, 1967) was a Czech chemist and inventor. Heyrovský was the inventor of the polarographic method, father of the electroanalytical method, and recipient of the Nobel Prize in 1959 for his invention and development of the polarographic methods of analysis. His main...
3
Analytical Chemistry
In 2005, Suskiewicz et al. classified the enzyme YwIE as a tyrosine phosphatase. And Kirstein et al. (2005) found that McsB is a tyrosine kinase that needs McsA to become activated. They also found that the interaction of McsA and McsB with CtsR results in the formation of a 3-protein complex that stops the binding of ...
1
Biochemistry
A mode of toxic action is a common set of physiological and behavioral signs that characterize a type of adverse biological response. A mode of action should not be confused with mechanism of action, which refer to the biochemical processes underlying a given mode of action. Modes of toxic action are important, widely ...
1
Biochemistry
The ohmic resistance appears in series with the electrode impedance of the reaction and the Nyquist diagram is translated to the right.
7
Physical Chemistry
Any of the thermodynamic potentials may be held constant during a process. For example: * An isenthalpic process introduces no change in enthalpy in the system.
7
Physical Chemistry
Sea salt is mentioned in the Vinaya Pitaka, a Buddhist scripture compiled in the mid-5th century BC. The principle of production is evaporation of the water from the sea brine. In warm and dry climates this may be accomplished entirely by using solar energy, but in other climates fuel sources have been used. Modern sea...
9
Geochemistry
The word "litmus" comes from an Old Norse word for “moss used for dyeing”. About 1300, the Spanish physician Arnaldus de Villa Nova began using litmus to study acids and bases. From the 16th century onwards, the blue dye was extracted from some lichens, especially in the Netherlands.
3
Analytical Chemistry
In FRAP, a region is briefly exposed to intense light, irrecoverably photobleaching fluorophores, and the fluorescence recovery due to diffusion of nearby (non-bleached) fluorophores is imaged. A primary advantage of FRAP over FCS is the ease of interpreting qualitative experiments common in cell biology. Differences b...
7
Physical Chemistry
The Crich β-mannosylation in organic chemistry is a synthetic strategy which is used in carbohydrate synthesis to generate a 1,2-cis-glycosidic bond. This type of linkate is generally very difficult to make, and specific methods like the Crich β-mannosylation are used to overcome these issues. The technique takes its n...
0
Organic Chemistry
In thermodynamics, a thermodynamicist is someone who studies thermodynamic processes and phenomena, i.e. the physics that deal with mechanical action and relations of heat. Among the well-known number of famous thermodynamicists, include Sadi Carnot, Rudolf Clausius, Willard Gibbs, Hermann von Helmholtz, and Max Planck...
7
Physical Chemistry
Hydroalumination of alkynes may be either stereospecifically cis or trans depending on the conditions employed. When a dialkylalane such as di(isobutyl)aluminium hydride (DIBAL-H) is used, the hydrogen and aluminium delivered from the reagent end up cis in the resulting alkenylalane. This stereospecificity can be expla...
0
Organic Chemistry
This detector is mostly used with alkali atoms, having a low ionization potential, with applications in mass spectrometry and atomic clocks.
3
Analytical Chemistry
Anabolic processes build organs and tissues. These processes produce growth and differentiation of cells and increase in body size, a process that involves synthesis of complex molecules. Examples of anabolic processes include the growth and mineralization of bone and increases in muscle mass.
1
Biochemistry
Computational methods have been applied to search for parameters (e.g. residue propensity, hydrophobicity, planarity) that could distinguish glycan-binding proteins from other surface patches. For example, a model trained on 19 non-homologous carbohydrate binding structures was able to predict carbohydrate-binding dom...
1
Biochemistry
Unlike other GDNF family of ligands, persephin only contains one RXXR cleavage site, rather than multiple, indicating that it can only make one length of functional peptide.
1
Biochemistry
Microwave radiation was applied in electrochemical methods in 1998 when Frank Marken and Richard G. Compton in Oxford placed a piece of platinum wire inside a microwave cavity in small electrochemical cell.
5
Photochemistry
An area denial weapon is a defensive device used to prevent an adversary from occupying or traversing an area of land, sea or air. The specific method may not be totally effective in preventing passage, but is sufficient to severely restrict, slow down, or endanger the opponent. Some area denial weapons pose risks to c...
1
Biochemistry
The discovery of the Nef reaction and the papers about divalent carbon (carbenes) were his major achievements.
0
Organic Chemistry
The nucleophilic lysine residue is commonly targeted site in protein bioconjugation, typically through amine-reactive N-hydroxysuccinimidyl (NHS) esters. To obtain optimal number of deprotonated lysine residues, the pH of the aqueous solution must be below the pKa of the lysine ammonium group, which is around 10.5, so ...
1
Biochemistry
Chromatin Immunoprecipitation results in production of complex mixtures of relatively short DNA fragments, which is challenging to amplify with MDA without causing a bias in the fragment representation. A method to circumvent this problem was proposed, which is based on conversion of these mixtures to circular concatem...
1
Biochemistry
Hexosaminidases (Hex) are important glycoside hydrolases for the generation of plant-specific paucimannosidic proteins across Plantae. HEXO1-HEXO3 have been reported to be key mediators of paucimannose expression in various plant species including Nicotiana benthamiana, A.thaliana and L. japonicus. Moreover, α1,3-fucos...
1
Biochemistry
Metabolic labeling of glycans can be used as a way to detect glycan structures. A well-known strategy involves the use of azide-labeled sugars which can be reacted using the Staudinger ligation. This method has been used for in vitro and in vivo imaging of glycans.
0
Organic Chemistry
Scolytus multistriatus, one of the vectors of the Dutch elm disease, uses vanillin as a signal to find a host tree during oviposition.
0
Organic Chemistry
DNA is precipitated by first ensuring that the correct concentration of positive ions is present in solution (too much will result in a lot of salt co-precipitating with DNA, too little will result in incomplete DNA recovery) and then adding two to three volumes of at least 95% ethanol. Many protocols advise storing DN...
1
Biochemistry
The type of a mass spectrometer most widely used with MALDI is the time-of-flight mass spectrometer (TOF), mainly due to its large mass range. The TOF measurement procedure is also ideally suited to the MALDI ionization process since the pulsed laser takes individual shots rather than working in continuous operation. M...
1
Biochemistry
Adverse effects include nausea, indigestion, diarrhea, constipation, gastrointestinal ulceration, headache, dizziness, rash, salt and fluid retention, and high blood pressure. Infrequent adverse effects include esophageal ulceration, heart failure, high blood levels of potassium, kidney impairment, confusion, and bronc...
4
Stereochemistry
The development of methods to detect and identify biomolecules has been motivated by the ability to improve the study of molecular structure and interactions. Before the advent of fluorescent labeling, radioisotopes were used to detect and identify molecular compounds. Since then, safer methods have been developed th...
1
Biochemistry
In some cases in the EU MRLs are also used for ornamental produce, and checked against MRLs for food crops. While this is a sound approach for the general environmental impact, it doesnt reflect potential exposure of people handling ornamentals. A swap test can eliminate this gap. MRLs for ornamental produce can someti...
2
Environmental Chemistry
References to silicon carbide heating elements exist from the early 20th century when they were produced by Acheson's Carborundum Co. in the U.S. and EKL in Berlin. Silicon carbide offered increased operating temperatures compared with metallic heaters. Silicon carbide elements are used today in the melting of glass an...
8
Metallurgy
Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate component and an amine component. The isocyanate can be aromatic or aliphatic in nature. It can be monomer, polymer, or any variant reaction of isocyanates, quasi-prepolymer or a prepolymer. The prepolymer, or quasi-prepolymer, c...
7
Physical Chemistry
The discovery of mTOR was made in 1994 while investigating the mechanism of action of its inhibitor, rapamycin. Rapamycin was first discovered in 1975 in a soil sample from Easter Island of South Pacific, also known as Rapa Nui, from where its name is derived. Rapamycin is a macrolide, produced by the microorganism Str...
1
Biochemistry
In case (b), the spin-orbit coupling is weak or non-existent (in the case ). In this case, we take and and assume precesses quickly around the internuclear axis. The good quantum numbers in case (b) are , , , and . We express the rotational energy operator as , where is a rotational constant. The rotational leve...
7
Physical Chemistry
Cation-exchange capacity is measured by displacing all the bound cations with a concentrated solution of another cation, and then measuring either the displaced cations or the amount of added cation that is retained. Barium (Ba) and ammonium (NH) are frequently used as exchanger cations, although many other methods are...
9
Geochemistry
Dalton's law expresses the fact that the total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of the individual gases in the mixture. This equality arises from the fact that in an ideal gas, the molecules are so far apart that they do not interact with each other. Most actual real-wor...
7
Physical Chemistry
The list of synthetic polymers, roughly in order of worldwide demand, includes polyethylene, polypropylene, polystyrene, polyvinyl chloride, synthetic rubber, phenol formaldehyde resin (or Bakelite), neoprene, nylon, polyacrylonitrile, PVB, silicone, and many more. More than 330 million tons of these polymers are made ...
7
Physical Chemistry
In chemistry, "activation" refers to the reversible transition of a molecule into a nearly identical chemical or physical state, with the defining characteristic being that this resultant state exhibits an increased propensity to undergo a specified chemical reaction. Thus, activation is conceptually the opposite of p...
7
Physical Chemistry
A number of formal [2+2+2] cycloadditions have been realized under Nb catalysis, including alkyne trimerizations and couplings of alkynes with alkenes or nitriles to form cyclohexadienes or pyridines, respectively. Typically a Nb(III) catalyst will form a Nb(V) metallocyclopropene with a terminal alkyne component and t...
0
Organic Chemistry
Enantiopure tert-butanesulfinamide can be prepared by enantioselective oxidation of inexpensive di-tert-butyl disulfide to the thiosulfinate followed by disulfide bond cleavage by lithium amide. In the original scope the chiral ligand used together with vanadyl acetylacetonate was prepared by condensing an optically pu...
0
Organic Chemistry
Thermochemical equations can be changed, as mentioned above, by multiplying by any numerical coefficient. All agents must be multiplied, including ΔH. Using the thermochemical equation of variables as above, one gets the following example. :A + B → C :ΔH= (±) # One must assume that A needs to be multiplied by two in or...
7
Physical Chemistry
The gradation of soils, or soil texture, affects water and nutrient holding and drainage capabilities. For sand-based soils, particle size can be the dominant characteristic affecting soil performances and hence crop. Sieving has long been the technique of choice for soil texture analysis, although laser diffraction in...
3
Analytical Chemistry
Organic Letters is a biweekly peer-reviewed scientific journal covering research in organic chemistry. It was established in 1999 and is published by the American Chemical Society. In 2014, the journal moved to a hybrid open access publishing model. The founding editor-in-chief was Amos Smith. The current editor-in-chi...
0
Organic Chemistry
High-energy ion beams produced by particle accelerators are used in atomic physics, nuclear physics and particle physics.
7
Physical Chemistry
Lithium is structurally similar to other cations such as sodium, potassium, magnesium and calcium, this causes lithium to activate potassium channels which inhibit neuromuscular transmission. Patients who take lithium can have a prolonged response to both depolarising and nondepolarising NMBAs.
1
Biochemistry
Ultraviolet in sewage treatment is commonly replacing chlorination. This is in large part because of concerns that reaction of the chlorine with organic compounds in the waste water stream could synthesize potentially toxic and long lasting chlorinated organics and also because of the environmental risks of storing chl...
5
Photochemistry
We have to distinguish between line source AAS (LS AAS) and continuum source AAS (CS AAS). In classical LS AAS, as it has been proposed by Alan Walsh, the high spectral resolution required for AAS measurements is provided by the radiation source itself that emits the spectrum of the analyte in the form of lines that ar...
3
Analytical Chemistry
The MAM is a critical signaling, metabolic, and trafficking hub in the cell that allows for the integration of ER and mitochondrial physiology. Coupling between these organelles is not simply structural but functional as well and critical for overall cellular physiology and homeostasis. The MAM thus offers a perspectiv...
1
Biochemistry
Cyanosulfidic prebiotic synthesis is a proposed mechanism for the origin of the key chemical building blocks of life. It involves a systems chemistry approach to synthesize the precursors of amino acids, ribonucleotides, and lipids using the same starting reagents and largely the same plausible early Earth conditions. ...
9
Geochemistry
The geologic component of the carbon cycle operates slowly in comparison to the other parts of the global carbon cycle. It is one of the most important determinants of the amount of carbon in the atmosphere, and thus of global temperatures. Most of the Earths carbon is stored inertly in the Earths lithosphere. Much of ...
5
Photochemistry
Caldoramide is a pentapeptide isolated from the cyanobacteria Caldora penicillata. It has cytotoxic effects on cancer cells and has been the subject of extensive oncological research. It is structurally analogous to belamide A and dolastatin 15. Its appearance is that of a powdery, white, substance.
1
Biochemistry
Platelet-derived growth factor receptors (PDGF-R) are cell surface tyrosine kinase receptors for members of the platelet-derived growth factor (PDGF) family. PDGF subunits -A and -B are important factors regulating cell proliferation, cellular differentiation, cell growth, development and many diseases including cancer...
1
Biochemistry
Not every interaction between a photon and an atom, or molecule, will result in photoionization. The probability of photoionization is related to the photoionization cross section of the species – the probability of an ionization event conceptualized as a hypothetical cross-sectional area. This cross section depends on...
7
Physical Chemistry
The Secretin family are peptides that act as local hormones which regulate activity of G-protein coupled receptors. Most often found in the pancreas and the intestines. Secretin was discovered in 1902 by E. H. Starling. It was later linked to chemical regulation and was the first substance to be deemed a hormone. #Secr...
1
Biochemistry
Nicotinamide adenine dinucleotide has several essential roles in metabolism. It acts as a coenzyme in redox reactions, as a donor of ADP-ribose moieties in ADP-ribosylation reactions, as a precursor of the second messenger molecule cyclic ADP-ribose, as well as acting as a substrate for bacterial DNA ligases and a grou...
5
Photochemistry
The genome of the P1 phage is moderately large, around 93Kbp in length (compared to the genomes of e.g. T4 - 169Kbp, lambda - 48Kbp and Ff - 6.4Kbp). In the viral particle it is in the form of a linear double stranded DNA molecule. Once inserted into the host it circularizes and replicates as a plasmid. In the viral p...
1
Biochemistry
The 1,3-enyne moiety is an important structural unit for biologically active and natural compounds. It can be derived from vinylic systems and terminal acetylenes by using a configuration-retention stereospecific procedure such as the Sonogashira reaction. Vinyl iodides are the most reactive vinyl halides to Pd oxidati...
0
Organic Chemistry
Norsteroids (nor-, L. norma, from "normal" in chemistry, indicating carbon removal) are a structural class of steroids that have had an atom or atoms (typically carbon) removed, biosynthetically or synthetically, from positions of branching off of rings or side chains (e.g., removal of methyl groups), or from within ri...
1
Biochemistry
The NDUFAF6 gene encodes a protein that localizes to mitochondria. The encoded protein plays an important role in the assembly of complex I (NADH-ubiquinone oxidoreductase) of the mitochondrial respiratory chain through regulation of subunit ND1 biogenesis.
1
Biochemistry
Although only being able to produce short hydrogel fibers, production of hydrogel fiber by polymerizing the hydrogel network inside a tubular mold and push out the fiber forcefully can also be achieved. But the friction will increase with the increasing length, and only short hydrogel fibers are feasible. A case would ...
7
Physical Chemistry
When two or more types of ligands (L, L, ...) are coordinated to an octahedral metal centre (M), the complex can exist as isomers. The naming system for these isomers depends upon the number and arrangement of different ligands.
4
Stereochemistry
A kairomone (a coinage using the Greek καιρός opportune moment, paralleling pheromone) is a semiochemical, emitted by an organism, which mediates interspecific interactions in a way that benefits an individual of another species which receives it and harms the emitter. This "eavesdropping" is often disadvantageous to t...
1
Biochemistry
Boiling is also a phase transition from the liquid phase to gas phase, but boiling is the formation of vapor as bubbles of vapor below the surface of the liquid. Boiling occurs when the equilibrium vapor pressure of the substance is greater than or equal to the atmospheric pressure. The temperature at which boiling occ...
7
Physical Chemistry
In 1834, Théophile-Jules Pelouze distilled tartaric acid and isolated glutaric acid and another unknown organic acid. Jöns Jacob Berzelius characterized this other acid the following year and named pyruvic acid because it was distilled using heat. The correct molecular structure was deduced by the 1870s. Pyruvic acid ...
1
Biochemistry
Methanogenesis or biomethanation is the formation of methane coupled to energy conservation by microbes known as methanogens. Organisms capable of producing methane for energy conservation have been identified only from the domain Archaea, a group phylogenetically distinct from both eukaryotes and bacteria, although ma...
1
Biochemistry
An inclusion is a solid particle in liquid aluminium alloy. It is usually non-metallic and can be of different nature depending on its source.
8
Metallurgy
Rudd joined the glycobiology institute at the University of Oxford in 1985. At the time, it was difficult for women scientists to secure jobs as academic personnel, and Rudd joined as a glass washer. She learned how to work with glycoproteins and large sugars and eventually completed a doctorate on glycoforms at the Op...
1
Biochemistry
*A phase is a form of matter that is homogeneous in chemical composition and physical state. Typical phases are solid, liquid and gas. Two immiscible liquids (or liquid mixtures with different compositions) separated by a distinct boundary are counted as two different phases, as are two immiscible solids. *The number ...
7
Physical Chemistry
In heterotrimeric G proteins, catalysis of GTP can be assisted by aluminum tetrafluoride () and RGS4. Heterotrimeric G proteins are larger three-part proteins serve in signal transduction of many pathways. The catalytic mechanism for GTP hydrolysis in heterotrimeric G proteins consists of an active state where catalysi...
1
Biochemistry
was a Japanese organic chemist and marine biologist, and professor emeritus at Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts and Boston University School of Medicine. He was awarded the Nobel Prize in Chemistry in 2008 for the discovery and development of green fluorescent protein (GFP) with two Ameri...
0
Organic Chemistry
Type J (iron–constantan) has a more restricted range (−40 °C to +750 °C) than type K but higher sensitivity of about 50 μV/°C. The Curie point of the iron (770 °C) causes a smooth change in the characteristic, which determines the upper temperature limit. Note, the European/German Type L is a variant of the type J, wit...
8
Metallurgy
Very little is known about the initiation of epigenetic silencing of transposable elements, and aside from the rare exception to this rule, as in the gene Muk, present as an initiator of regulatory epigenetic modification in maize, there are many other unclear aspects of how transposons are regulated in plant genomes. ...
1
Biochemistry
EXPOSE has several objectives, specific to each experiments, but all linked to the astrobiology domain. Their collective objective is to better understand the nature and evolution of organic matter present in extraterrestrial environments and their potential implications in astrobiology. These experiments mostly study ...
1
Biochemistry
Kinesin-13 MCAK (Mitotic Centromere-Associated Kinesin) is a KRP that is involved in resolving errors during mitosis involving kinetochore-microtubules. This process is associated with Aurora B Protein Kinase. When Aurora Bs function is disrupted, MCAK ability to locate centromeres, which play a critical role in separa...
1
Biochemistry
The best Lewis structure for an oxocarbenium ion contains an oxygen–carbon double bond, with the oxygen atom attached to an additional group and consequently taking on a formal positive charge. In the language of canonical structures (or "resonance"), the polarization of the π bond is described by a secondary carbocat...
0
Organic Chemistry
Beginning with this initial sequence:<br /> The complement created by base pairing is:<br /> The reverse complement is:<br /> And, the inverted repeat sequence is:<br /> "nnnnnn" represents any number of intervening nucleotides.
1
Biochemistry
Phillips started his academic career as an assistant professor at the University of Illinois Urbana-Champaign, followed by his appointment as a professor of biochemistry at Rice University in 1987. In 1993, he assumed the position of Rice Scientia Lecturer, subsequently receiving the Robert A. Welch Lecturer appointmen...
1
Biochemistry
Another potential route to ecosystem impacts is through bioacoustics. This may occur as ocean acidification can alter the acoustic properties of seawater, allowing sound to propagate further, and increasing ocean noise. This impacts all animals that use sound for echolocation or communication.
9
Geochemistry
In biology, iron plays a number of roles. Iron is widespread in most living organisms and is essential for their function. In microbes, iron redox chemistry is utilized as an electron donor or receptor in microbial metabolism, allowing microbes to generate energy. In the oceans, iron is essential for the growth and sur...
9
Geochemistry
Progesterone, like pregnenolone and dehydroepiandrosterone (DHEA), belongs to an important group of endogenous steroids called neurosteroids. It can be metabolized within all parts of the central nervous system. Neurosteroids are neuromodulators, and are neuroprotective, neurogenic, and regulate neurotransmission and m...
0
Organic Chemistry
Floral scent emissions of most flowering plants vary predictably throughout the day, following a circadian rhythm. This variation is controlled by light intensity. Maximal emissions coincide with peaks of the highest activity of visiting pollinators. For instance, snapdragon flowers, mostly pollinated by bees, have the...
1
Biochemistry
Agreed-upon reference materials are required so that reported δ values are comparable among studies. For the sulfur isotope system, δS values are reported on the Vienna-Cañon Diablo Troilite (VCDT) scale. The original CDT scale was based on a sample of the mineral troilite recovered from the Canyon Diablo meteorite at ...
9
Geochemistry
A Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, is a catalyst used in the synthesis of polymers of 1-alkenes (alpha-olefins). Two broad classes of Ziegler–Natta catalysts are employed, distinguished by their solubility: * Heterogeneous supported catalysts based on titanium compounds are used in pol...
7
Physical Chemistry
Undervirilization can occur if a genetic male cannot produce enough androgen or the body tissues cannot respond to it. Extreme undervirilization occurs when no significant androgen hormones can be produced or the body is completely insensitive to androgens. Both result in a female body. Partial undervirilization produc...
1
Biochemistry
Ferrosilicon is an alloy of iron and silicon with a typical silicon content by weight of 15–90%. It contains a high proportion of iron silicides.
8
Metallurgy
Tumor development is a complex process that requires cell division, growth, and survival. One approach used by tumors to upregulate growth and survival is through autocrine production of growth and survival factors. Autocrine signaling plays critical roles in cancer activation and also in providing self-sustaining grow...
1
Biochemistry
Aliphatic compounds can be saturated, joined by single bonds (alkanes), or unsaturated, with double bonds (alkenes) or triple bonds (alkynes). If other elements (heteroatoms) are bound to the carbon chain, the most common being oxygen, nitrogen, sulfur, and chlorine, it is no longer a hydrocarbon, and therefore no long...
0
Organic Chemistry
A complete description of hypervalent molecules arises from consideration of molecular orbital theory through quantum mechanical methods. An LCAO in, for example, sulfur hexafluoride, taking a basis set of the one sulfur 3s-orbital, the three sulfur 3p-orbitals, and six octahedral geometry symmetry-adapted linear combi...
4
Stereochemistry
The diaphragm is an important part of the body's digestive system. The muscular diaphragm separates the thoracic cavity from the abdominal cavity where most of the digestive organs are located. The suspensory muscle attaches the ascending duodenum to the diaphragm. This muscle is thought to be of help in the digestive ...
1
Biochemistry