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Polyphenols of several classes are widespread in plants, including anthocyanins, phytoestrogens, and tannins. Polyphenols are secondary metabolites produced by almost every part of plants, including fruits, flowers, leaves and bark. | 1 | Biochemistry |
The first contribution to van der Waals forces is due to electrostatic interactions between rotating permanent dipoles, quadrupoles (all molecules with symmetry lower than cubic), and multipoles. It is termed the Keesom interaction, named after Willem Hendrik Keesom. These forces originate from the attraction between permanent dipoles (dipolar molecules) and are temperature dependent.
They consist of attractive interactions between dipoles that are ensemble averaged over different rotational orientations of the dipoles. It is assumed that the molecules are constantly rotating and never get locked into place. This is a good assumption, but at some point molecules do get locked into place. The energy of a Keesom interaction depends on the inverse sixth power of the distance, unlike the interaction energy of two spatially fixed dipoles, which depends on the inverse third power of the distance. The Keesom interaction can only occur among molecules that possess permanent dipole moments, i.e., two polar molecules. Also Keesom interactions are very weak van der Waals interactions and do not occur in aqueous solutions that contain electrolytes. The angle averaged interaction is given by the following equation:
where d = electric dipole moment, = permitivity of free space, = dielectric constant of surrounding material, T = temperature, = Boltzmann constant, and r = distance between molecules. | 6 | Supramolecular Chemistry |
The main areas of use are the conversion of ketones to esters (Baeyer-Villiger oxidation), epoxidation of alkenes (Prilezhaev reaction), conversion of silyl enol ethers to silyl α-hydroxy ketones (Rubottom oxidation), oxidation of sulfides to sulfoxides and sulfones, and oxidation of amines to produce amine oxides. The following scheme shows the epoxidation of cyclohexene with mCPBA.
The epoxidation mechanism is concerted: the cis or trans geometry of the alkene starting material is retained in the epoxide ring of the product. The transition state of the Prilezhaev reaction is given below:
The geometry of the transition state, with the peracid bisecting the C-C double bond, allows the two primary frontier orbital interactions to occur: π (HOMO) to σ* (LUMO) and n (HOMO, regarded as a filled p orbital on a sp hybridized oxygen) to π* (LUMO), corresponding, in arrow-pushing terms, to formation of one C-O bond and cleavage of the O-O bond and formation of the other C-O bond and cleavage of the C=C π bond. | 0 | Organic Chemistry |
CARS spectroscopy can be used for temperature measurements; because the CARS signal is temperature dependent. The strength of the signal scales (non-linearly) with the difference in the ground state population and the vibrationally excited state population. Since the population of states follows the temperature dependent Boltzmann distribution, the CARS signal carries an intrinsic temperature dependence as well. This temperature dependence makes CARS a popular technique for monitoring the temperature of hot gases and flames. | 3 | Analytical Chemistry |
Breath analysis is a convenient and non-invasive way to detect chemicals in a bodily system such as alcohol content to determine intoxication, monitor the levels of anesthetics in the body during surgical procedures, and identify performance-enhancing substances in the system of athletes. However, conventional techniques are ineffective at low concentrations. An electrospray ionization interface assisted by an ion funnel used in a linear trap quadrupole Fourier-transform ion cyclotron resonance mass spectrometer was shown to greatly increase sensitivity with high resolution. | 7 | Physical Chemistry |
LAGP-based membranes have been applied as separators in lithium-sulfur batteries. LAGP allows the transfer of lithium ions from anode to cathode but, at the same time, prevents the diffusion of polysulfides from the cathode, suppressing the polysulfide shuttle effect and enhancing the overall performance of the battery. Typically, all-solid-state lithium-sulfur batteries are not fabricated because of high interfacial resistance; therefore, hybrid electrolytes are usually realized, in which LAGP acts as a barrier against polysulfide diffusion but it is combined with liquid or polymer electrolytes to promote fast lithium diffusion and to improve the interfacial contact with electrodes. | 7 | Physical Chemistry |
There are three classes of multiple sclerosis: relapsing-remitting (RRMS), primary progressive (PPMS) and secondary progressive (SPMS). Gene regulatory network (GRN) plays a vital role to understand the disease mechanism across these three different multiple sclerosis classes. | 1 | Biochemistry |
Bottles of di-tert-butyl dicarbonate buildup of internal pressure in sealed containers caused by its slow decomposition to di-tert-butyl carbonate and ultimately tert-butanol and CO in the presence of moisture. For this reason, it is usually sold and stored in plastic bottles rather than glass ones.
The main hazard of the reagent is its inhalational toxicity. Its median lethal concentration of 100 mg/m over 4 hours in rats is comparable to that of phosgene (49 mg/m over 50 min in rats). | 0 | Organic Chemistry |
Finally, fluids with an even higher molecular complexity can exhibit non-classical behavior in the single-phase vapor region near saturation. They are called Bethe-Zel’dovich-Thompson (BZT) fluids, from the name of physicists Hans Bethe, Yakov Zel'dovich, and Philip Thompson, who first worked on these kinds of fluids.
For thermodynamic conditions lying in the non-classical regime, the non-monotone evolution of the Mach number in isentropic expansions can be found even in subsonic conditions. In fact, for values of , positive values of can be reached also in subsonic flows (). In other words, the non-monotone Mach number evolution is also possible in the convergent section of an isentropic nozzle.
Moreover, a peculiar phenomenon of the non-classical regime is the so-called inverted gas-dynamics. In the classical regime, expansions are smooth isentropic processes, while compressions occur through shock waves, which are discontinuities in the flow. If gas-dynamics is inverted, the opposite occurs, namely rarefaction shock waves are physically admissible and compressions occur through smooth isentropic processes.
As a consequence of the negative value of , two other peculiar phenomena can occur for BZT fluids: shock splitting and composite waves. Shock splitting occurs when an inadmissible pressure discontinuity evolves in time by generating two weaker shock waves. Composite waves, instead, are referred to as phenomena in which two elementary waves propagate as a single entity.
Experimental evidence of a non-classical gas-dynamic regime is not available yet. The main reasons are the complexity of performing experiments in such challenging thermodynamic conditions and the thermal stability of these very complex molecules. | 7 | Physical Chemistry |
The bond coat adheres the thermal barrier to the substrate. Additionally, the bond coat provides oxidation protection and functions as a diffusion barrier against the motion of substrate atoms towards the environment. The five major types of bond coats are: the aluminides, the platinum-aluminides, MCrAlY, cobalt-cermets, and nickel-chromium. For aluminide bond coatings, the coatings final composition and structure depends on the substrate composition. Aluminides lack ductility below 750 °C, and exhibit limited thermomechanical fatigue strength. Pt-aluminides are similar to the aluminide bond coats except for a layer of Pt (5—10 μm) deposited on the blade. The Pt aids in oxide adhesion and contributes to hot corrosion, increasing blade lifespan. MCrAlY does not strongly interact with the substrate. Normally applied by plasma spraying, MCrAlY coatings from secondary aluminum oxides. This means that the coatings form an outer chromia layer and a secondary alumina layer underneath. These oxide formations occur at high temperatures in the range of those that superalloys usually encounter. The chromia provides oxidation and hot-corrosion resistance. The alumina controls oxidation mechanisms by limiting oxide growth by self-passivating. The yttrium enhances oxide adherence to the substrate, and limits the growth of grain boundaries (which can lead to coat flaking). Addition of rhenium and tantalum increases oxidation resistance. Cobalt-cermet-based coatings consisting of materials such as tungsten carbide/cobalt can be used due to excellent resistance to abrasion, corrosion, erosion, and heat. These cermet coatings perform well in situations where temperature and oxidation damage are significant concerns, such as boilers. One of cobalt cermets unique advantages is minimal loss of coating mass over time, due to the strength of carbides. Overall, cermet coatings are useful in situations where mechanical demands are equal to chemical demands. Nickel-chromium coatings are used most frequently in boilers fed by fossil fuels, electric furnaces, and waste incineration furnaces, where the danger of oxidizing agents and corrosive compounds in the vapor must be addressed. The specific method of spray-coating depends on the coating composition. Nickel-chromium coatings that also contain iron or aluminum provide better corrosion resistance when they are sprayed and laser glazed, while pure nickel-chromium coatings perform better when thermally sprayed exclusively. | 8 | Metallurgy |
The method is proposed as an assay that employs both cfDNA whole genome methylation sequencing and fragmentomic feature information for multicancer classification. Copy number ratios calculated for healthy and cancerous tissues are used as a cancer type and cancer existence identifier. As done in EPIC-seq, the method also utilizes fragment lengths. Short fragment over long fragment ratio is used in the method as an identifier score. Using the single base or region level methylation percentages on detected cancer methylation markers for each cancer type, copy number ratios, and short/long fragment ratios; the method employs a custom Support Vector Machines algorithm to classify the cancer type if there exists one. This method reports the cancer detection and tissue-of-origin of 4 cancer types. However, it requires detection of specific methylation sites/regions of interest for cancer types | 1 | Biochemistry |
Instrumentation in time-domain diffuse optics consists of three fundamental components namely, a pulsed laser source, a single photon detector and a timing electronics. | 7 | Physical Chemistry |
µSR requires a particle accelerator for the production of a muon beam. This is presently achieved at few large scale facilities in the world: the CMMS continuous source at TRIUMF in Vancouver, Canada; the SµS continuous source at the Paul Scherrer Institut (PSI) in Villigen, Switzerland; the ISIS Neutron and Muon Source and RIKEN-RAL pulsed sources at the Rutherford Appleton Laboratory in Chilton, United Kingdom; and the J-PARC facility in Tokai, Japan, where a new pulsed source is being built to replace that at KEK in Tsukuba, Japan.
Muon beams are also available at the Laboratory of Nuclear Problems, Joint Institute for Nuclear Research (JINR) in Dubna, Russia.
The International Society for µSR Spectroscopy (ISMS) exists to promote the worldwide advancement of µSR. Membership in the society is open free of charge to all individuals in academia, government laboratories and industry who have an interest in the society's goals. | 7 | Physical Chemistry |
Cyclohexenone is an organic compound which is a versatile intermediate used in the synthesis of a variety of chemical products such as pharmaceuticals and fragrances. It is colorless liquid, but commercial samples are often yellow.
Industrially, cyclohexenone is prepared from phenol by Birch reduction.
Cyclohexenone is a ketone, or more precisely an enone. Common reactions include nucleophilic conjugate addition with organocopper reagents, Michael reactions and Robinson annulations. | 0 | Organic Chemistry |
Despite the low oxygen conditions, organisms have evolved to live in and around OMZs. For those organisms, like the vampire squid, special adaptations are needed to either make do with lesser amounts of oxygen or to extract oxygen from the water more efficiently. For example, the giant red mysid (Gnathophausia ingens) continues to live aerobically (using oxygen) in OMZs. They have highly developed gills with large surface area and thin blood-to-water diffusion distance that enables effective removal of oxygen from the water (up to 90% O removal from inhaled water) and an efficient circulatory system with high capacity and high blood concentration of a protein (hemocyanin) that readily binds oxygen.
Another strategy used by some classes of bacteria in the oxygen minimum zones is to use nitrate rather than oxygen, thus drawing down the concentrations of this important nutrient. This process is called denitrification. The oxygen minimum zones thus play an important role in regulating the productivity and ecological community structure of the global ocean. For example, giant bacterial mats floating in the oxygen minimum zone off the west coast of South America may play a key role in the region's extremely rich fisheries, as bacterial mats the size of Uruguay have been found there. | 9 | Geochemistry |
Some other methods to produce LAGP materials have been reported in literature works, including liquid-based techniques, spark plasma sintering, and co-precipitation.
In the following table, some ionic conductivity values are reported for LAGP materials produced with different synthesis routes, in the case of optimized production and annealing conditions. | 7 | Physical Chemistry |
Protocell research has created controversy and opposing opinions, including criticism of vague definitions of "artificial life". The creation of a basic unit of life is the most pressing ethical concern, although the most widespread worry about protocells is their potential threat to human health and the environment through uncontrolled replication.
Additionally, postulation into the conditions for protocellular origins of life on Earth remain debated. Scientists in the field emphasize the importance of further hypothesis based experimentation over theoretical conjecture to more concretely constrain the prebiotic plausibility of different protocell morphologies, geologic conditions, and synthetic schemes. | 9 | Geochemistry |
Diastereomeric recrystallisation is a method of chiral resolution of enantiomers from a racemic mixture. It differs from asymmetric synthesis, which aims to produce a single enantiomer from the beginning, in that diastereomeric recrystallisation separates two enantiomers that have already mixed into a single solution.
The strategy of diastereomeric recrystallisation involves two steps. The first step is to convert the enantiomers into diastereomers by way of a chemical reaction. A mixture of enantiomers may contain two isomers of a molecule with one chiral center. After adding a second chiral center in a determined location, the two isomers are still different, but they are no longer mirror images of each other; rather, they become diastereomers.
In a prototypical example, a mixture of R and S enantiomers with one chiral center would become a mixture of (R,S) and (S,S) diastereomers. (The R-S notation is explained here.) The conversion of the enantiomeric mixture into a diastereomer pair, depending on the nature of the chemicals, can be via covalent bond formation with the enantiopure resolving agent, or by salt formation, the latter being particularly convenient since acid base chemistry is typically quite operationally simple and high yielding.
The second step, once the diastereomers have formed, is to separate them using recrystallisation. This is possible because enantiomers have shared physical properties such as melting point and boiling point, but diastereomers have different chemical properties, so they can be separated like any two different molecules. It is these, now different, physical properties e.g. Melting point & Enthalpy of fusion which determine the eutectic composition (see Eutectic system) which correlates with the maximum yield of pure diastereomer in the crystallization (R, see example melting point phase diagram of a diastereomeric system across all compositions in Figure 1). Various methods have been developed to screening diastereomeric resolutions by determining the eutectic composition as a means of ranking for yield efficiency. | 4 | Stereochemistry |
The TSH index is reduced in patients with secondary hypothyroidism resulting from thyrotropic insufficiency. For this indication, it has, however, up to now only been validated in adults. JTI was also found reduced in cases of TACITUS syndrome (non-thyroidal illness syndrome) as an example of type 1 thyroid allostasis. Conversely, an elevated thyroid function index may serve as a biomarker for type 2 allostasis and contextual stress.
Jostel's TSH index may decrease under therapy with the antidiabetic drug metformin, especially in women under oral contraceptives.
In two large population-based cohorts included in the Study of Health in Pomerania differentially correlated to some markers of body composition. Correlation was positive to body mass index (BMI), waist circumference and fat mass, but negative to body cell mass. With the exception of fat mass all correlations were age-dependent. Very similar observations have been made earlier in the NHANES dataset.
In Parkinson's disease, JTI is significantly elevated in early sub-types of the disease compared to an advanced group.
A longitudinal study in euthyroid subjects with structural heart disease found that JTI predicts the risk of malignant arrhythmia including ventricular fibrillation and ventricular tachycardia. This applies to both incidence and event-free survival. It was therefore concluded that an elevated set point of thyroid homeostasis may contribute to cardiovascular risk. A positive correlation of JTI to SIQALS 2, a score for allostatic load, suggests that thyroid hormones are among the mediators linking stress to major cardiovascular endpoints.
Another study demonstrated the TSH index to inversely correlate to thyroid's secretory capacity and thyroid volume. It is unclear if this finding reflects shortcomings of the index (i.e. low specificity in the setting of subclinical hypothyroidism) or plastic responses of the pituitary gland to beginning hypothyroidism.
In subjects with type 2 diabetes, treatment with beta blockers resulted in increased TSH index, but the mechanism is unclear.
Negative correlation of Jostel's TSH index to the urinary excretion of certain phthalates suggests that endocrine disruptors may affect the central set point of thyroid homeostasis. | 1 | Biochemistry |
Storeys research includes studies of enzyme properties, gene expression, protein phosphorylation, epigenetics, and cellular signal transduction mechanisms to seek out the basic principles of how organisms endure and flourish under extreme conditions. He is particularly known within the field of cryobiology for his studies of animals that can survive freezing, especially the frozen "frog-sicles" (Rana sylvatica) that have made his work popular with multiple TV shows and magazines. Storeys studies of the adaptations that allow frogs, insects, and other animals to survive freezing have made major advances in the understanding of how cells, tissues and organs can endure freezing. Storey was also responsible for the discovery that some turtle species are freeze tolerant: newly hatched painted turtles that spend their first winter on land (Chrysemys picta marginata & C. p. bellii). These turtles are unique as they are the only reptiles, and highest vertebrate life form, known to tolerate prolonged natural freezing of extracellular body fluids during winter hibernation. These advances may aid the development of organ cryopreservation technology. A second area of his research is metabolic rate depression - understanding the mechanisms by which some animals can reduce their metabolism and enter a state of hypometabolism or torpor that allows them to survive prolonged environmental stresses. His studies have identified molecular mechanisms that underlie metabolic arrest across phylogeny and that support phenomena including mammalian hibernation, estivation, and anoxia- and ischemia-tolerance. These studies hold key applications for medical science, particularly for preservation technologies that aim to extend the survival time of excised organs in cold or frozen storage. Additional applications include insights into hyperglycemia in metabolic syndrome and diabetes, and anoxic and ischemic damage caused by heart attack and stroke. Furthermore, Storey's lab has created several web based programs freely available for [http://www.kenstoreylab.com/research-tools/ data management, data plotting, and microRNA analysis]. | 1 | Biochemistry |
Current U.S. assay offices include the following:
* The Philadelphia Mint – 1792 to date
* The Denver Mint – 1862 to date. It served as an assay office until 1906, when coinage operations began.
* The San Francisco Mint – 1852 to date. Coinage operations were suspended in March 1955, but the plant continued to operate as an assay office. In 1962, its official designation was changed from mint to assay office. Coinage operations were again authorized in 1965.
* The West Point, New York Bullion Depository – 1938 to date. It is operated as an adjunct of the New York Assay Office. | 3 | Analytical Chemistry |
Lawessons reagent (LR) is a chemical compound used in organic synthesis as a thiation agent. Lawessons reagent was first made popular by Sven-Olov Lawesson, who did not, however, invent it. Lawesson's reagent was first made in 1956 during a systematic study of the reactions of arenes with PS. | 0 | Organic Chemistry |
Isotopic effect expressed with the equations given above only refer to reactions that can be described with first-order kinetics. In all instances in which this is not possible, transient kinetic isotope effects should be taken into account using the GEBIK and GEBIF equations. | 7 | Physical Chemistry |
The compound with empirical formula FeSn is the first known kagome magnet. It is an intermetallic compound composed of iron (Fe) and tin (Sn), with alternating planes of FeSn and Sn. | 8 | Metallurgy |
Most aliphatic compounds are flammable, allowing the use of hydrocarbons as fuel, such as methane in natural gas for stoves or heating; butane in torches and lighters; various aliphatic (as well as aromatic) hydrocarbons in liquid transportation fuels like petrol/gasoline, diesel, and jet fuel; and other uses such as ethyne (acetylene) in welding. | 0 | Organic Chemistry |
The P-N bond is susceptible to attack by protic reagents. Alcoholysis occurs readily:
:PhPNEt + ROH → PhPOR + HNEt
The P-N bond reverts to the chloride upon treatment with anhydrous hydrogen chloride:
:PhPNEt + 2 HCl → PhPCl + [HNEt]Cl
Similarly, transamination is used in the conversion of one aminophosphine to another:
:P(NMe) + RNH P(NR)(NMe) + HNMe
With tris(dimethylamino)phosphine is a reactant, the equilibrium can be driven by evaporation of dimethylamine.
Since the P-NR bond is not attacked by Grignard reagents, aminophosphine chlorides are useful reagents in the preparation of unsymmetrical tertiary phosphines. Illustrative is the conversion of dimethylaminophosphorus dichloride to chlorodimethylphosphine:
:2 MeMgBr + MeNPCl → MeNPMe + 2 MgBrCl
:MeNPMe + 2 HCl → ClPMe + MeNHCl
Illustrative also is the chemistry of 1,2-bis(dichlorophosphino)benzene, a versatile precursor to diphosphine ligands, is prepared using aminophosphine reagents. It is prepared from 1,2-dibromobenzene via lithiation and treatment with (EtN)PCl (Et = ethyl). This route gives CH[P(NEt)], which is treated with hydrogen chloride:
:CH[P(NEt)] + 8 HCl → CH(PCl) + 4 EtNHCl | 0 | Organic Chemistry |
Naturally occurring polymers such as cotton, starch, and rubber were familiar materials for years before synthetic polymers such as polyethene and perspex appeared on the market. Many commercially important polymers are synthesized by chemical modification of naturally occurring polymers. Prominent examples include the reaction of nitric acid and cellulose to form nitrocellulose and the formation of vulcanized rubber by heating natural rubber in the presence of sulfur. Ways in which polymers can be modified include oxidation, cross-linking, and end-capping. | 7 | Physical Chemistry |
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production.
Coenzyme A (CoASH or CoA) consists of a β-mercaptoethylamine group linked to pantothenic acid (vitamin B5) through an amide linkage and 3'-phosphorylated ADP. The acetyl group (indicated in blue in the structural diagram on the right) of acetyl-CoA is linked to the sulfhydryl substituent of the β-mercaptoethylamine group. This thioester linkage is a "high energy" bond, which is particularly reactive. Hydrolysis of the thioester bond is exergonic (−31.5 kJ/mol).
CoA is acetylated to acetyl-CoA by the breakdown of carbohydrates through glycolysis and by the breakdown of fatty acids through β-oxidation. Acetyl-CoA then enters the citric acid cycle, where the acetyl group is oxidized to carbon dioxide and water, and the energy released is captured in the form of 11 ATP and one GTP per acetyl group.
Konrad Bloch and Feodor Lynen were awarded the 1964 Nobel Prize in Physiology or Medicine for their discoveries linking acetyl-CoA and fatty acid metabolism. Fritz Lipmann won the Nobel Prize in 1953 for his discovery of the cofactor coenzyme A. | 1 | Biochemistry |
Polanyis model of adsorption was met with much criticism for several decades after publication years. His simplistic model for determining adsorption was formed during the time of the discovery of Debyes fixed dipoles, Bohr's atomic model, and well as the developing theory of intermolecular forces and electrostatic forces by key figures in the chemistry world including W.H. Bragg, W.L. Bragg, and Willem Hendrik Keesom.
Opponents of his model claimed that Polanyis theory did not take into account these emerging theories. Criticism included that the model did not take into account the electrical interactions of the gas and the surface, and that the presence of other molecules would screen off the attraction of the gas to the surface. Polanyis model was furthermore put under scrutiny following the experimental claims of Irving Langmuir from 1916 to 1918 through whose research would eventually win the Nobel Prize in 1932.
However, Polanyi was not able to participate in many of these discussions because he served as a medical officer for the Austro-Hungarian army in the Serbian front during World War I. Polanyi wrote about this experience saying: | 7 | Physical Chemistry |
Most metal carbonyl complexes contain a mixture of ligands. Examples include the historically important IrCl(CO)(P(CH)) and the antiknock agent (CHCH)Mn(CO). The parent compounds for many of these mixed ligand complexes are the binary carbonyls, those species of the formula [M(CO)], many of which are commercially available. The formulae of many metal carbonyls can be inferred from the 18-electron rule. | 0 | Organic Chemistry |
Bina Shaheen Siddiqui is a Pakistani chemist and the Director of the H.E.J. Research Institute of Chemistry at the University of Karachi. Siddiqui graduated from the University of Karachi with an MPhil in 1978. In 1980, she graduated from the same university with a PhD in organic chemistry.
She specialises in the chemical components of Pakistan's indigenous plants. She was elected to The World Academy of Sciences in 1989, and was elected a Fellow of the Pakistan Academy of Sciences in 1997. She is also a Fellow of the Chemical Society of Pakistan. | 0 | Organic Chemistry |
For historical reasons discussed below, a few types of carbon-containing compounds, such as carbides, carbonates (excluding carbonate esters), simple oxides of carbon (for example, CO and carbon dioxide|) and cyanides are generally considered inorganic compounds. Different forms (allotropes) of pure carbon, such as diamond, graphite, fullerenes and carbon nanotubes are also excluded because they are simple substances composed of a single element and so not generally considered chemical compounds.
The word "organic" in this context does not mean "natural". | 0 | Organic Chemistry |
The bx1 gene encodes a protein, BX1, that forms indol from indol-3-glycerol phosphate in the plastid. It is the first step in the pathway and determines much of the natural variation in levels of DIMBOA in maize. The next steps in the pathway occur in the endoplasmic reticulum, also referred to as the microsomes in cell fractionation experiments, and are carried by proteins encoded by genes bx2, bx3, bx4, and bx5. | 1 | Biochemistry |
In chemistry, a nucleofuge () is a leaving group which retains the lone pair of electrons from its previous bond with another species. For example, in the S2 mechanism, a nucleophile attacks an organic compound containing the nucleofuge (the bromo group) which simultaneously breaks the bond with the nucleofuge.
After a reaction nucleofuges may contain either a negative or a neutral charge; this is governed by the nature of the specific reaction.
The word nucleofuge is commonly found in older literature, but its use is less common in current literature in which the term leaving group dominates. | 0 | Organic Chemistry |
A suggestion has been made that in the early stages of the Earths development when its radioactivity was almost two orders of magnitude higher than at present, radiolysis could have been the principal source of atmospheric oxygen, which ensured the conditions for the origin and development of life. Molecular hydrogen and oxidants produced by the radiolysis of water may also provide a continuous source of energy to subsurface microbial communities (Pedersen, 1999). Such speculation is supported by a discovery in the Mponeng Gold Mine in South Africa, where the researchers found a community dominated by a new phylotype of Desulfotomaculum', feeding on primarily radiolytically produced H. | 5 | Photochemistry |
A submitochondrial particle (SMP) is an artificial vesicle made from the inner mitochondrial membrane. They can be formed by subjecting isolated mitochondria to sonication, freezing and thawing, high pressure, or osmotic shock. SMPs can be used to study the electron transport chain in a cell-free context.
The process of SMP formation forces the inner mitochondrial membrane inside out, meaning that the matrix-facing leaflet becomes the outer surface of the SMP, and the intermembrane space-facing leaflet faces the lumen of the SMP. As a consequence, the F particles which normally face the matrix are exposed. Chaotropic agents can destabilize F particles and cause them to dissociate from the membrane, thereby uncoupling the final step of oxidative phosphorylation from the rest of the electron transport chain. | 1 | Biochemistry |
Immunoelectrophoresis is a general name for a number of biochemical methods for separation and characterization of proteins based on electrophoresis and reaction with antibodies. All variants of immunoelectrophoresis require immunoglobulins, also known as antibodies, reacting with the proteins to be separated or characterized. The methods were developed and used extensively during the second half of the 20th century. In somewhat chronological order: Immunoelectrophoretic analysis (one-dimensional immunoelectrophoresis ad modum Grabar), crossed immunoelectrophoresis (two-dimensional quantitative immunoelectrophoresis ad modum Clarke and Freeman or ad modum Laurell), rocket-immunoelectrophoresis (one-dimensional quantitative immunoelectrophoresis ad modum Laurell), fused rocket immunoelectrophoresis ad modum Svendsen and Harboe, affinity immunoelectrophoresis ad modum Bøg-Hansen. | 1 | Biochemistry |
Photolithotrophs such as plants obtain energy from light and therefore use inorganic electron donors such as water only to fuel biosynthetic reactions (e. g., carbon dioxide fixation in lithoautotrophs). | 1 | Biochemistry |
Copper technology may date back to the 4th millennium BCE in the Himalaya region.
It is the first element to be discovered in metallurgy,
Copper and its alloys were also used to create copper-bronze images such as Buddhas or Hindu/Mahayana Buddhist deities. Xuanzang also noted that there were copper-bronze Buddha images in Magadha. In Varanasi, each stage of the image manufacturing process is handled by a specialist.
Other metal objects made by Indian artisans include lamps. Copper was also a component in the razors for the tonsure ceremony.
One of the most important sources of history in the Indian subcontinent are the royal records of grants engraved on copper-plate grants (tamra-shasan or tamra-patra). Because copper does not rust or decay, they can survive indefinitely. Collections of archaeological texts from the copper-plates and rock-inscriptions have been compiled and published by the Archaeological Survey of India during the past century. The earliest known copper-plate known as the Sohgaura copper-plate is a Maurya record that mentions famine relief efforts. It is one of the very few pre-Ashoka Brahmi inscriptions in India. | 8 | Metallurgy |
Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometrical parameters that determine the position of each atom.
Molecular geometry influences several properties of a substance including its reactivity, polarity, phase of matter, color, magnetism and biological activity. The angles between bonds that an atom forms depend only weakly on the rest of molecule, i.e. they can be understood as approximately local and hence transferable properties. | 4 | Stereochemistry |
Quinone methides are cross-conjugated rather than aromatic. Nucleophilic addition at the exo-cyclic double bond will result in rearomatisation, making such reactions highly favourable. As a result, quinone methides are excellent, electrophilic Michael acceptors, react quickly with nucleophiles and can be easily reduced. They are able to act as radical scavengers via a similar process, a behaviour exploited by certain polymerisation inhibitors. Quinone methides are more polar than quinones, and therefore more chemically reactive. Simple unhindered quinone methides are short lived reactive intermediates that are not stable enough to be isolated under normal circumstances, they will trimerise in the absence of nucleophiles. Sterically hindered quinone methides can be sufficiently stable to be isolated, with some examples being commercially available. | 0 | Organic Chemistry |
Ideally, the reference set in CAI is composed of highly expressed genes, so that CAI provides an indication of gene expression level under the assumption that there is translational selection to optimize gene sequences according to their expression levels. The rationale for this is dual: highly expressed genes need to compete for resources (i.e. ribosomes) in fast-growing organisms and it makes sense for them to be also more accurately translated. Both hypotheses lead to highly expressed genes using mostly codons for tRNA species that are abundant in the cell. | 1 | Biochemistry |
Generally speaking, there are two distinct mechanistic pathways that lead to C-C bond activation: (a) the β-carbon elimination of metal complexes. In this mechanism, a M–C intermediate and a double bond are formed at the same time; and (b) the direct oxidative addition of C–C bonds into low-valent metal adducts to form a bis(organyl)metal complex. | 0 | Organic Chemistry |
High intensity ultrashort pulse lasers can create ATI features with 20 or more peaks. The photoelectron spectrum of electron energies is continuous since actual light sources contain a spread of energies. | 7 | Physical Chemistry |
In chemistry, metal-catalysed hydroboration is a reaction used in organic synthesis. It is one of several examples of homogeneous catalysis. | 0 | Organic Chemistry |
Some metabolic myopathies involve the under- or over-utilization of the purine nucleotide cycle. Metabolic myopathies cause a low ATP reservoir in muscle cells (ADP > ATP), resulting in exercise-induced excessive AMP buildup in muscle, and subsequent exercise-induced hyperuricemia (myogenic hyperuricemia) through conversion of excessive AMP into uric acid by way of either AMP → adenosine or AMP → IMP.
During strenuous exercise, AMP is created through the use of the adenylate kinase (myokinase) reaction after the phosphagen system has been depleted of creatine phosphate and not enough ATP is being produced yet by other pathways (see above reaction in Occurrence section). In those affected by metabolic myopathies, exercise that normally wouldn't be considered strenuous for healthy people, is however strenuous for them due to their low ATP reservoir in muscle cells. This results in regular use of the myokinase reaction for normal, everyday activities.
Besides the myokinase reaction, a high ATP consumption and low ATP reservoir also increases protein catabolism and salvage of IMP, which results in increased AMP and IMP. These two nucleotides can then enter the purine nucleotide cycle to produce fumarate which will then produce ATP by oxidative phosphorylation. If the purine nucleotide cycle is blocked (such as AMP deaminase deficiency) or if exercise is stopped and increased fumarate production is no longer needed, then the excess nucleotides will be converted into uric acid. | 1 | Biochemistry |
Single-cell transcriptomics uses sequencing techniques similar to single cell genomics or direct detection using fluorescence in situ hybridization. The first step in quantifying the transcriptome is to convert RNA to cDNA using reverse transcriptase so that the contents of the cell can be sequenced using NGS methods as was done in genomics. Once converted, there is not enough cDNA to be sequenced so the same DNA amplification techniques discussed in single cell genomics are applied to the cDNA to make sequencing possible. Alternately, fluorescent compounds attached to RNA hybridization probes are used to identify specific sequences and sequential application of different RNA probes will build up a comprehensive transcriptome. | 1 | Biochemistry |
Propanephosphonic acid anhydride (PPAA, T3P) is an anhydride of propanephosphonic acid. Its structure is a cyclic trimer, with a phosphorus–oxygen core and propyl groups and additional oxygens attached. The chemical is a useful reagent for peptide synthesis reactions, where it activates the carboxylic acid partner for subsequent reaction with amines. It is commercially available as 50 % solution in DMF or ethyl acetate as a slightly yellow mixture. | 0 | Organic Chemistry |
Froth flotation is a process for separating minerals from gangue by exploiting differences in their hydrophobicity. Hydrophobicity differences between valuable minerals and waste gangue are increased through the use of surfactants and wetting agents. The flotation process is used for the separation of a large range of sulfides, carbonates and oxides prior to further refinement. Phosphates and coal are also upgraded (purified) by flotation technology. "Grade-recovery curves" are tools for weighing the trade-off of producing a high grade of concentrate vs cost. These curves only compare the grade-recovery relations of a specific feed grade and feed rate. | 8 | Metallurgy |
More useful generally than the Gilman reagents are the so-called mixed cuprates with the formula [RCuX] and [RCuX]. Such compounds are often prepared by the addition of the organolithium reagent to copper(I) halides and cyanide. These mixed cuprates are more stable and more readily purified. One problem addressed by mixed cuprates is the economical use of the alkyl group. Thus, in some applications, the mixed cuprate has the formula is prepared by combining thienyllithium and cuprous cyanide followed by the organic group to be transferred. In this higher order mixed cuprate, both the cyanide and thienyl groups do not transfer, only the R group does. | 0 | Organic Chemistry |
A non-combustible material is a substance that does not ignite, burn, support combustion, or release flammable vapors when subject to fire or heat, in the form in which it is used and under conditions anticipated. Any solid substance complying with either of two sets of passing criteria listed in Section 8 of ASTM E 136 when the substance is tested in accordance with the procedure specified in ASTM E 136 is considered to be non-combustible. | 7 | Physical Chemistry |
Perovskite solar cells are solar cells that include a perovskite-structured material as the active layer. Most commonly, this is a solution-processed hybrid organic-inorganic tin or lead halide based material. Efficiencies have increased from below 5% at their first usage in 2009 to 25.5% in 2020, making them a very rapidly advancing technology and a hot topic in the solar cell field. Researchers at University of Rochester reported in 2023 that significant further improvements in cell efficiency can be achieved by utilizing Purcell effect.
Perovskite solar cells are also forecast to be extremely cheap to scale up, making them a very attractive option for commercialisation. So far most types of perovskite solar cells have not reached sufficient operational stability to be commercialised, although many research groups are investigating ways to solve this. Energy and environmental sustainability of perovskite solar cells and tandem perovskite are shown to be dependent on the structures. Photonic front contacts for light management can improve the perovskite cells' performance, via enhanced broadband absorption, while allowing better operational stability due to protection against the harmful high-energy (above Visible) radiation. The inclusion of the toxic element lead in the most efficient perovskite solar cells is a potential problem for commercialisation. | 7 | Physical Chemistry |
Ancyronyx, commonly known as spider water beetles or spider riffle beetles, is a genus of aquatic riffle beetles from North America, South Asia, China, and Southeast Asia. They are small beetles with extremely long legs ending in strong claws. Both the adults and the larvae are found underwater in the shallow riffles of streams and rivers, clinging to rocks or submerged wood. They feed on algae and decaying wood tissue. The genus contains twenty-one species, eleven of which are endemic to the Philippines. | 2 | Environmental Chemistry |
Black shales are organic rich, microlaminated sedimentary rocks often associated with bottom water anoxia. This is because anoxia slows the degradation of organic matter, allowing for greater burial in the sediments. Other evidence for anoxic burial of black shale includes the lack of bioturbation, meaning that there were no organisms burrowing into the sediment because there was no oxygen for respiration. There must also be a source of organic matter for burial, generally from production near the oxic surface. Many papers discussing ancient euxinic events use the presence of black shale as a preliminary proxy for anoxic bottom waters, but their presence does not in and of itself indicate euxinia or even strong anoxia. Generally geochemical testing is needed to provide better evidence for conditions. | 9 | Geochemistry |
The model represents individuals as networks of interacting transcriptional regulators. Each individual expresses genes encoding transcription factors. The product of each gene can regulate the expression level of itself and/or the other genes through cis-regulatory elements. The interactions among genes constitute a gene network that is represented by a × regulatory matrix in the model. The elements in matrix R represent the interaction strength. Positive values within the matrix represent the activation of the target gene, while negative ones represent repression. Matrix elements with value 0 indicate the absence of interactions between two genes. | 1 | Biochemistry |
There is an overall 2–3 kcal/mol error using the Benson group-increment theory to calculate the ΔH. The value of each group is estimated on the base of the average ΔΔH° shown above and there will be a dispersion around the average ΔΔH°. Also, it can only be as accurate as the experimental accuracy. That's the derivation of the error, and there is nearly no way to make it more accurate. | 7 | Physical Chemistry |
Heme A differs from heme B in that a methyl side chain at ring position 8 is oxidized to a formyl group and a hydroxyethylfarnesyl group, an isoprenoid chain, has been attached to the vinyl side chain at ring position 2 of the iron tetrapyrrole heme. Heme A is similar to heme o, in that both have this farnesyl addition at position 2 but heme O does not have the formyl group at position 8, still containing the methyl group. The correct structure of heme A, based upon NMR and IR experiments of the reduced, Fe(II) form of the heme, was published in 1975. The structure was confirmed by synthesis of the dimethyl ester of the iron-free form. | 1 | Biochemistry |
* Phase Change Material (PCM) Based Energy Storage Materials and Global Application Examples, Zafer URE M.Sc., C.Eng. MASHRAE [https://www.pcmproducts.net/Building_Temperature_Control.htm HVAC Applications]
* Phase Change Material Based Passive Cooling Systems Design Principal and Global Application Examples, Zafer URE M.Sc., C.Eng. MASHRAE [https://www.pcmproducts.net/Passive_Enclosure_Cooling.htm Passive Cooling Application] | 7 | Physical Chemistry |
Beyond the most common perovskite symmetries (cubic, tetragonal, orthorhombic), a more precise determination leads to a total of 23 different structure types that can be found. These 23 structure can be categorized into 4 different so-called tilt systems that are denoted by their respective Glazer notation.
The notation consists of a letter a/b/c, which describes the rotation around a Cartesian axis and a superscript +/—/0 to denote the rotation with respect to the adjacent layer. A “+” denotes that the rotation of two adjacent layers points in the same direction, whereas a “—” denotes that adjacent layers are rotated in opposite directions. Common examples are aaa, aaa and aaa which are visualized here. | 3 | Analytical Chemistry |
After a WGD, one of the duplicated gene pair is often lost through fractionation; less than 10% of WGD gene pairs have remained in S. cerevisiae genome. A little over half of WGD gene pairs in the glycolysis reaction pathway were retained in post-WGD species, significantly higher than the overall retention rate. This has been associated with an increased ability to metabolize glucose into pyruvate, or higher rate of glycolysis. After glycolysis, pyruvate can either be further broken down by pyruvate decarboxylase (Pdc) or pyruvate dehydrogenase (Pdh). The kinetics of the enzymes are such that when pyruvate concentrations are high, due to a high rate of glycolysis, there is increased flux through Pdc and thus the fermentation pathway. The WGD is believed to have played a beneficial role in the evolution of the Crabtree effect in post-WGD species partially due to this increase in copy number of glycolysis genes. | 1 | Biochemistry |
Multiple displacement amplification (MDA) is a DNA amplification technique. This method can rapidly amplify minute amounts of DNA samples to a reasonable quantity for genomic analysis. The reaction starts by annealing random hexamer primers to the template: DNA synthesis is carried out by a high fidelity enzyme, preferentially Φ29 DNA polymerase. Compared with conventional PCR amplification techniques, MDA does not employ sequence-specific primers but amplifies all DNA, generates larger-sized products with a lower error frequency, and works at a constant temperature. MDA has been actively used in whole genome amplification (WGA) and is a promising method for application to single cell genome sequencing and sequencing-based genetic studies. | 1 | Biochemistry |
In analytical chemistry, argentometry is a type of titration involving the silver(I) ion. Typically, it is used to determine the amount of chloride present in a sample. The sample solution is titrated against a solution of silver nitrate of known concentration. Chloride ions react with silver(I) ions to give the insoluble silver chloride:
: Ag (aq) + Cl (aq) → AgCl (s) (K = 5.88 × 10) | 3 | Analytical Chemistry |
In 2017, two research groups from ETH Zurich and from MIT reported on the creation of an ultracold quantum gas with supersolid properties. The Zurich group placed a Bose–Einstein condensate inside two optical resonators, which enhanced the atomic interactions until they started to spontaneously crystallize and form a solid that maintains the inherent superfluidity of Bose–Einstein condensates. This setting realises a special form of a supersolid, the so-called lattice supersolid, where atoms are pinned to the sites of an externally imposed lattice structure. The MIT group exposed a Bose–Einstein condensate in a double-well potential to light beams that created an effective spin–orbit coupling. The interference between the atoms on the two spin–orbit coupled lattice sites gave rise to a characteristic density modulation.
In 2019, three groups from Stuttgart, Florence, and Innsbruck observed supersolid properties in dipolar Bose–Einstein condensates formed from lanthanide atoms. In these systems, supersolidity emerges directly from the atomic interactions, without the need for an external optical lattice. This facilitated also the direct observation of superfluid flow and hence the definitive proof for the existence of the supersolid state of matter.
In 2021, dysprosium was used to create a 2-dimensional supersolid quantum gas. In 2022, the same team created a supersolid disk in a round trap.
In 2021, confocal cavity quantum electrodynamics with a Bose–Einstein condensate was used to create a supersolid that possesses a key property of solids, vibration. That is, a supersolid was created that possesses lattice phonons with a Goldstone mode dispersion exhibiting a 16 cm/s speed of sound. | 7 | Physical Chemistry |
Standard reduction potentials in aqueous solution are also a useful way of predicting the non-aqueous chemistry of the metals involved. Thus, metals with high negative potentials, such as sodium, or potassium, will ignite in air, forming the respective oxides. These fires cannot be extinguished with water, which also react with the metals involved to give hydrogen, which is itself explosive. Noble metals, in contrast, are disinclined to react with oxygen and, for that reason (as well as their scarcity) have been valued for millennia, and used in jewellery and coins.
The adjacent table lists standard reduction potential in volts; electronegativity (revised Pauling); and electron affinity values (kJ/mol), for some metals and metalloids.
The simplified entries in the reaction column can be read in detail from the Pourbaix diagrams of the considered element in water. Noble metals have large positive potentials; elements not in this table have a negative standard potential or are not metals.
Electronegativity is included since it is reckoned to be, "a major driver of metal nobleness and reactivity".
On account of their high electron affinity values, the incorporation of a noble metal in the electrochemical photolysis process, such as platinum and gold, among others, can increase photoactivity.
Arsenic and antimony are usually considered to be metalloids rather than noble metals. However, physically speaking their most stable allotropes are metallic. Semiconductors, such as selenium and tellurium, have been excluded.
The black tarnish commonly seen on silver arises from its sensitivity to hydrogen sulfide:
:2 Ag + HS + O → AgS + HO.
Rayner-Canham contends that, "silver is so much more chemically-reactive and has such a different chemistry, that it should not be considered as a noble metal." In dentistry, silver is not regarded as a noble metal due to its tendency to corrode in the oral environment.
The relevance of the entry for water is addressed by Li et al. in the context of galvanic corrosion. Such a process will only occur when:
:"(1) two metals which have different electrochemical potentials are...connected, (2) an aqueous phase with electrolyte exists, and (3) one of the two metals has...potential lower than the potential of the reaction ( + 4e + = 4 OH</sup>)."
The superheavy elements from hassium (element 108) to livermorium (116) inclusive are expected to be "partially very noble metals"; chemical investigations of hassium has established that it behaves like its lighter congener osmium, and preliminary investigations of nihonium and flerovium have suggested but not definitively established noble behavior. Copernicium's behaviour seems to partly resemble both its lighter congener mercury and the noble gas radon. | 8 | Metallurgy |
Overload, shocks and vibrations (bridges, roads submitted to intense truck traffic...) can induce mechanical stress and deformations in concrete structures and be responsible for the mechanical degradation of concrete. Beside the long-term drying shrinkage of concrete, pre-stressed and post-tensioned civil engineering structures (bridges, primary containment domes of nuclear power plants can also undergo slow concrete creep and deformation. | 8 | Metallurgy |
Hanna Reisler (née Bregman) is an Israeli-American Professor of Chemistry at the University of Southern California. She is interested in the reaction dynamics of molecules and free radicals, as well as the photodissociation in the gas phase. Reisler established the University of Southern California Women In Science and Engineering (WISE) program. | 7 | Physical Chemistry |
In some cases, discordant reads can also indicate a CNV for example in sequences repeats. For larger CNV, the density of the reads will vary accordingly to the copy number. An increase of copy numbers will be reflected by increasing mapping of the same region on the reference genome. | 1 | Biochemistry |
[4+4] reactions are forbidden in the ground state and often entropically disfavored in the excited state. The mechanism of the [4+4] photocycloaddition is proposed to begin with the photoexcitation of a 1,3-diene system into the excited state. Because the orbital symmetry of the highest occupied molecular orbital (HOMO) in the excited diene is the same as that of the lowest unoccupied molecular orbital (LUMO) in another ground state diene, they are able to form an exciplex that decays to form the closed cyclooctane ring structure. Below is a Frontier Molecular Orbital diagram depicting the interaction between the two molecules of dienes. | 5 | Photochemistry |
On 29 November 2018, Chinese authorities suspended all of Hes research activities, saying his work was "extremely abominable in nature" and a violation of Chinese law. He was sequestered in a university apartment under some sort of surveillance. On 21 January 2019, He was fired from his job at SUSTech and his teaching and research work at the university was terminated. The same day, the Guangdong Province administration investigated the "gene editing baby incident", which is explicitly prohibited by the state. On 30 December 2019, the Shenzhen Nanshan District Peoples Court sentenced He Jiankui to three years in prison and with a fine of 3 million RMB (about US$ in 2019).
Among the collaborators, only two were indicted – Zhang Renli of the Guangdong Academy of Medical Sciences and Guangdong General Hospital, received a two-year prison sentence and a 1-million RMB (about US$) fine, and Qin Jinzhou of the Southern University of Science and Technology received an 18-month prison sentence and a 500,000 RMB (about US$) fine. The three were found guilty of having "forged ethical review documents and misled doctors into unknowingly implanting gene-edited embryos into two women." Zhang and Qin were officially banned from working in assisted reproductive technology for life. In April 2022, He was released from prison.
On 26 November 2018, The CRISPR Journal published ahead of print an article by He, Ryan Ferrell, Chen Yuanlin, Qin Jinzhou, and Chen Yangran in which the authors justified the ethical use of CRISPR gene editing in humans. As the news of CRISPR babies broke out, the editors reexamined the paper and retracted it on 28 December, announcing:Michael W. Deem, an American bioengineering professor at Rice University and his doctoral advisor was involved in the research, and was present when people involved in the study gave consent. He was the only non-Chinese out of 10 authors listed in the manuscript submitted to Nature'. Deem came under investigation by Rice University after news of the work was made public. As of 2022, the university never issued any information on his conduct. He resigned from the university in 2020, and pursued a business by creating a bioengineering and energy consultant company called Certus LLC.
Stanford University also investigated its faculty of Hes confidants including William Hurlbut, Matthew Porteus, and Stephen Quake, his main mentor in gene editing. The universitys review committee concluded that the accused "were not participants in [He Jiankui’s] research regarding genome editing of human embryos for intended implantation and birth and that they had no research, financial or organizational ties to this research."
In response to He's work, the World Health Organization, formed a committee comprising "a global, multi-disciplinary expert panel" called the Expert Advisory Committee on Developing Global Standards for Governance and Oversight of Human Genome Editing "to examine the scientific, ethical, social and legal challenges associated with human genome editing (both somatic and germline)" in December 2018. In 2019, it issued a call to halt all work on human genome editing, and launched a global registry to track research in the field. It had issued three reports for the recommended guidelines on human genome editing since 2019. As of 2021, the committee stood by the grounds that while somatic gene therapies have become useful in several disease, germline and heritable human genome editing is still with risks, and should be banned.
In May 2019, Chinese government prepared gene-editing regulations stressing that anyone found manipulating the human genome by genome-editing techniques would be held responsible for any related adverse consequences. The Civil Code of the People's Republic of China was amended in 2020 that added Article 1009 which states: "any medical research activity associated with human gene and human embryo must comply with the relevant laws, administrative regulations and national regulation, must not harm individuals and violate ethical morality and public interest." It was enacted on 1 January 2021. A draft of the 11th Amendment to the Chinese Criminal Code in 2020 has incorporated three types of crime: the illegal practice of human gene editing, human embryo cloning and severe endangering of the security of human genetic resources; with penalties of imprisonment of up to 7 years and a fine.
As of December 2021, Vivien Marx reported in the Nature Biotechnology article that both children are healthy. | 1 | Biochemistry |
The aromatic component of the quinine molecule is a quinoline with a methoxy substituent. The amine component has a quinuclidine skeleton and the methylene bridge in between the two components has a hydroxyl group. The substituent at the 3 position is a vinyl group. The molecule is optically active with five stereogenic centers (the N1 and C4 constituting a single asymmetric unit), making synthesis potentially difficult because it is one of 16 stereoisomers. | 0 | Organic Chemistry |
Fluxes are materials added to the ore during smelting to catalyze the desired reactions and to chemically bind to unwanted impurities or reaction products. Calcium carbonate or calcium oxide in the form of lime are often used for this purpose, since they react with sulfur, phosphorus, and silicon impurities to allow them to be readily separated and discarded, in the form of slag. Fluxes may also serve to control the viscosity and neutralize unwanted acids.
Flux and slag can provide a secondary service after the reduction step is complete; they provide a molten cover on the purified metal, preventing contact with oxygen while still hot enough to readily oxidize. This prevents impurities from forming in the metal. | 8 | Metallurgy |
Some of the most commonly-used biocompatible materials (or biomaterials) are polymers due to their inherent flexibility and tunable mechanical properties. Medical devices made of plastics are often made of a select few including: cyclic olefin copolymer (COC), polycarbonate (PC), polyetherimide (PEI), medical grade polyvinylchloride (PVC), polyethersulfone (PES), polyethylene (PE), polyetheretherketone (PEEK) and even polypropylene (PP). To ensure biocompatibility, there are a series of regulated tests that material must pass to be certified for use. These include the United States Pharmacopoeia IV (USP Class IV) Biological Reactivity Test and the International Standards Organization 10993 (ISO 10993) Biological Evaluation of Medical Devices. The main objective of biocompatibility tests is to quantify the acute and chronic toxicity of material and determine any potential adverse effects during use conditions, thus the tests required for a given material are dependent on its end-use (i.e. blood, central nervous system, etc.). | 1 | Biochemistry |
Ions in their gas-like state are highly reactive and will rapidly interact with ions of opposite charge to give neutral molecules or ionic salts. Ions are also produced in the liquid or solid state when salts interact with solvents (for example, water) to produce solvated ions, which are more stable, for reasons involving a combination of energy and entropy changes as the ions move away from each other to interact with the liquid. These stabilized species are more commonly found in the environment at low temperatures. A common example is the ions present in seawater, which are derived from dissolved salts.
As charged objects, ions are attracted to opposite electric charges (positive to negative, and vice versa) and repelled by like charges. When they move, their trajectories can be deflected by a magnetic field.
Electrons, due to their smaller mass and thus larger space-filling properties as matter waves, determine the size of atoms and molecules that possess any electrons at all. Thus, anions (negatively charged ions) are larger than the parent molecule or atom, as the excess electron(s) repel each other and add to the physical size of the ion, because its size is determined by its electron cloud. Cations are smaller than the corresponding parent atom or molecule due to the smaller size of the electron cloud. One particular cation (that of hydrogen) contains no electrons, and thus consists of a single proton – much smaller than the parent hydrogen atom. | 7 | Physical Chemistry |
Preimplantation genetic screening (PGS) or preimplantation genetic diagnosis (PGD) has been suggested to be able to be used in IVF to select an embryo that appears to have the greatest chances for successful pregnancy. However, a systematic review and meta-analysis of existing randomised controlled trials came to the result that there is no evidence of a beneficial effect of PGS with cleavage-stage biopsy as measured by live birth rate. On the contrary, for those of advanced maternal age, PGS with cleavage-stage biopsy significantly lowers the live birth rate. Technical drawbacks, such as the invasiveness of the biopsy, and non-representative samples because of mosaicism are the major underlying factors for inefficacy of PGS.
Still, as an expansion of IVF, patients who can benefit from PGS/PGD include:
* Those who have a family history of inherited disease
* Those who want prenatal sex discernment. This can be used to diagnose monogenic disorders with sex linkage. It can potentially be used for sex selection, wherein a fetus is aborted if having an undesired sex.
* Those who already have a child with an incurable disease and need compatible cells from a second healthy child to cure the first, resulting in a "saviour sibling" that matches the sick child in HLA type.
PGS screens for numeral chromosomal abnormalities while PGD diagnosis the specific molecular defect of the inherited disease. In both PGS and PGD, individual cells from a pre-embryo, or preferably trophectoderm cells biopsied from a blastocyst, are analysed during the IVF process. Before the transfer of a pre-embryo back to a person's uterus, one or two cells are removed from the pre-embryos (8-cell stage), or preferably from a blastocyst. These cells are then evaluated for normality. Typically within one to two days, following completion of the evaluation, only the normal pre-embryos are transferred back to the uterus. Alternatively, a blastocyst can be cryopreserved via vitrification and transferred at a later date to the uterus. In addition, PGS can significantly reduce the risk of multiple pregnancies because fewer embryos, ideally just one, are needed for implantation. | 1 | Biochemistry |
Chiral recognition implies the ability of chiral stationery phases to interact differently with mirror-image molecules, leading to their separation. The mechanism of enantiomeric resolution using CSPs is generally attributed to the “three-point" interaction model (fig.1.) between the analyte and the chiral selector in the stationary phase. Also known as the Dalgliesh model. Under this model, for chiral recognition, and hence enantiomeric resolution to happen on a CSP one of the enantiomers of the analyte must be involved in three simultaneous interactions. This means to say the one of enantiomers is able to have a good interaction with the complimentary sites on the chiral selector attached to the CSP. While Its mirror-image partner may only interact at two or one such sites. In the figure, enantiomer (a), has the correct configuration of the ligands (X, Y and Z) for three-point interactions with the complimentary sites (X’, Y’ and Z’) on the CSP, while its mirror image (b) can only interact at one site. The dotted lines (-----) indicate interaction with complimentary sites.
The diastereomeric complexes thus formed will have different energies of interaction. The enantiomer forming the more stable complex will have less energy and stay longer in the stationary phase compared to the less stable complex with higher energy. The success of chiral separation basically depends in manipulating the subtle energy differences between the reversibly formed non-covalent transient diastereomeric complexes. The energy difference reflects the magnitude of enantioselectivity. Mobile phase has a major role in stabilizing the diastereomeric complex and thus in chiral separation. This simplified bimolecular interaction model is a treatment suitable for theoretical purposes. Mobile phase plays a key role in chiral recognition mechanism. Components of MP (such as bulk solvents, modifiers, buffer salts, additives) not only influence the conformational flexibility of CS and CA molecules but also their degree of ionization. The types of interaction involved in the analyte-selector interaction vary depending on the nature of the CSP used. These may include hydrogen bonding, dipole-dipole, π-π, electrostatic, hydrophobic or steric interactions, and inclusion complex formation. | 4 | Stereochemistry |
There is considerable interest in applying gene-editing methods to the treatment of diseases with a genetic component. However, there are multiple challenges associated with this approach. An effective treatment would require editing of a large number of target cells, which in turn would require an effective method of delivery and a great level of tissue specificity.
As of 2019, prime editing looks promising for relatively small genetic alterations, but more research needs to be conducted to evaluate whether the technology is efficient in making larger alterations, such as targeted insertions and deletions. Larger genetic alterations would require a longer RT template, which could hinder the efficient delivery of pegRNA to target cells. Furthermore, a pegRNA containing a long RT template could become vulnerable to damage caused by cellular enzymes. Prime editing in plants suffers from low efficiency ranging from zero to a few percent and needs significant improvement.
Some of these limitations have been mitigated by recent improvements to the prime editors, including motifs that protect pegRNAs from degradation. Further research is needed before prime editing could be used to correct pathogenic alleles in humans. Research has also shown that inhibition of certain MMR proteins, including MLH1 can improve prime editing efficiency. | 1 | Biochemistry |
In the 1920s and 30s, Albert H. Taylor, Arthur C. Hardy , and others of the General Electric company developed a series of instruments that were capable of easily recording spectral data "in reflection". Their display preference for the data was "% Reflectance". In 1946, Frank Benford published a series of parametric equations that gave results equivalent to the Stokes formulas. The formulas used fractions to express reflectance and transmittance. | 7 | Physical Chemistry |
Gestonorone caproate is the generic name of the drug and its , , and , while gestronol hexanoate is its . It has also been referred to as norhydroxyprogesterone caproate, and is also known by its former developmental code names SH-582 and SH-80582. | 4 | Stereochemistry |
* EAS Award for Outstanding Achievements in the Fields of Analytical Chemistry (2023)
* Martin Medal (2019)
* Ralph N. Adams Award in Bioanalyical Chemistry (2016)
* ACS Award in Chromatography (2017)
* CASSS Award for Outstanding Achievements in Separation Science (2017)
* Marcel Golay Award for Lifetime Achievement in Capillary Chromatography (2012)
* Eastern Analytical Symposium Award for Separation Science (2012)
* McKnight Award for Technical Innovations in Neuroscience (2010)
* Rackham Distinguished Faculty Achievement Award (2009)
* American Microchemical Society’s Benedetti-Pichler Memorial Award (2001) | 3 | Analytical Chemistry |
In IUPAC nomenclature, 1,1-ethenediyl describes the connectivity >C=CH. The related species ethenylidenes have the connectivity =C=CH. | 0 | Organic Chemistry |
Left-hand traffic (LHT) and right-hand traffic (RHT) are the practices, in bidirectional traffic, of keeping to the left side and to the right side of the road, respectively. They are fundamental to traffic flow, and are sometimes called the rule of the road. The terms right- and left-hand drive refer to the position of the driver and the steering wheel in the vehicle and are, in automobiles, the reverse of the terms right- and left-hand traffic. The rule also includes where on the road a vehicle is to be driven, if there is room for more than one vehicle in the one direction, and the side on which the vehicle in the rear overtakes the one in the front. For example, a driver in an LHT country would typically overtake on the right of the vehicle being overtaken.
RHT is used in 165 countries and territories, mainly in the Americas, Continental Europe, northern Africa and mainland Asia (except South Asia), while 75 countries use LHT, which account for about a sixth of the worlds land area, a quarter of its roads, and about a third of its population. In 1919, 104 of the worlds territories were LHT and an equal number were RHT. Between 1919 and 1986, 34 of the LHT territories switched to RHT.
Many of the countries using LHT were part of the British Empire, while others, including Indonesia, Japan, Nepal, Bhutan, Macao, Thailand, Mozambique, Suriname, United States Virgin Islands, Sweden and Iceland (which use RHT since September 1967 and late May 1968 respectively), were not. Most of the countries that were part of the French colonial empire adopted RHT.
Historical switches of traffic handedness have often been motivated by factors such as changes in political administration, a desire for uniformity within a country or with neighboring states, or availability and affordability of vehicles.
In LHT, traffic keeps left and cars usually have the steering wheel on the right (RHD: right-hand drive) and roundabouts circulate clockwise. RHT is the opposite: traffic keeps right, the driver usually sits on the left side of the car (LHD: left-hand drive), and roundabouts circulate counterclockwise.
In most countries, rail traffic follows the handedness of the roads; but many of the countries that switched road traffic from LHT to RHT did not switch their trains. Boat traffic on rivers is RHT, regardless of location. Boats are traditionally piloted from the starboard side to facilitate priority to the right. | 4 | Stereochemistry |
Low-pressure mercury lamps are very similar to a fluorescent lamp, with a wavelength of 253.7 nm (1182.5 THz).
The most common form of germicidal lamp looks similar to an ordinary fluorescent lamp but the tube contains no fluorescent phosphor. In addition, rather than being made of ordinary borosilicate glass, the tube is made of fused quartz or vycor 7913 glass. These two changes combine to allow the 253.7 nm ultraviolet light produced by the mercury arc to pass out of the lamp unmodified (whereas, in common fluorescent lamps, it causes the phosphor to fluoresce, producing visible light). Germicidal lamps still produce a small amount of visible light due to other mercury radiation bands.
An older design looks like an incandescent lamp but with the envelope containing a few droplets of mercury. In this design, the incandescent filament heats the mercury, producing a vapor which eventually allows an arc to be struck, short circuiting the incandescent filament.
As with all gas-discharge lamps, low- and high-pressure mercury lamps exhibit negative resistance and require the use of an external ballast to regulate the current flow. The older lamps that resembled an incandescent lamp were often operated in series with an ordinary 40 W incandescent "appliance" lamp; the incandescent lamp acted as the ballast for the germicidal lamp. | 5 | Photochemistry |
Ethyl eicosapentaenoic acid (E-EPA) is an ethyl ester of eicosapentaenoic acid, which is an omega-3 fatty acid. | 1 | Biochemistry |
#Microinject the embryo with DNA coding for transposase and a plasmid with the reporter gene and transposase recognition sequences (and often the E. coli reporter gene and origin of replication, etc.).
#Random transposition occurs, inserting the reporter gene randomly. The insertion tends to occur near actively transcribed genes, as this is where the chromatin structure is loosest, so the DNA is most accessible.
#Grow flies and cross to remove genetic variation between the cells of the organism (see above).
#Look for flies expressing the reporter gene. These have experienced a successful transposition, so can be investigated to determine the phenotype due to mutation of existing genes.
Possible mutations:
#Insertion in a translated region => hybrid protein/truncated protein. Usually causes loss of protein function, although more complex effects are seen.
#Insertion in an intron => altered splicing pattern/splicing failure. Usually results in protein truncation or the production of inactive mis-spliced products, although more complex effects are common.
#Insertion in 5 (the sequence that will become the mRNA 5 UTR) untranslated region => truncation of transcript. Usually results in failure of the mRNA to contain a 5' cap, leading to less efficient translation.
#Insertion in promoter => reduction/complete loss of expression. Always results in greatly reduced protein production levels. The most useful type of insertion for analysis due to the simplicity of the situation.
#Insertion between promoter and upstream enhancers => loss of enhancer function/hijack of enhancer function for reporter gene.† Generally reduces the level of protein specificity to cell type, although complex effects are often seen. | 1 | Biochemistry |
Notable members of The Electrochemical Society include numerous Nobel Prize laureates including the three co-winners of the 2019 Nobel Prize for Chemistry.
*Thomas Edison: Edison became a member on April 4, 1903. Early members recall attending a meeting at Edison's home in the Society’s early days. Edison is often credited for inventing the phonograph, the motion picture camera, and the electric light bulb.
*John B. Goodenough, M. Stanley Whittingham, and Akira Yoshino, all long-time ECS members, shared the 2019 Nobel Prize in Chemistry “for the development of lithium-ion batteries”.
*Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura shared the 2014 Nobel Prize in Physics for “the invention of efficient blue light-emitting diodes, which has enabled bright and energy-saving white light sources”.
*Jack Kilby’s invention of the integrated circuit earned him half of the 2000 Nobel Prize in Physics "for basic work on information and communication technology".
*Steven Chu and William D. Phillips were co-recipients of the 1997 Nobel Prize in Physics “for the development of methods to cool and trap atoms with laser light”.
*Richard Smalley shared the 1996 Nobel Prize in Chemistry “for the discovery of fullerenes”.
*Rudolph A. Marcus won the 1992 Nobel Prize in Chemistry “for his contributions to the theory of electron transfer reactions in chemical systems".
*Jean-Marie Lehn, an early innovator in the field of supramolecular chemistry, shared the 1987 Nobel Prize in Chemistry “for the development and use of molecules with structure-specific interactions of high selectivity”.
*Gerd Binnig shared the 1986 Nobel Prize in Physics “for the design of the scanning tunneling microscope”.
*[https://www.electrochem.org/publications/leadership-collections Charles W. Tobias]: A pioneer in the field of electrochemical engineering, Tobias made a long-lasting and far-reaching impact on the field of electrochemical science by forming the Chemical Engineering Department at UC Berkeley in 1947. He served as ECS president from 1970-1971.
*Gordon E. Moore: The co-founder of Intel was known for his 1965 principle which made possible the delivery of more powerful and lower-costing semiconductor chips. This was later known as Moore's law.
*Norman Hackerman: The internationally known expert in metal corrosion served as ECS president from 1957-1958. Hackerman is most recognized for developing the electrochemistry of oxidation.
*Carl Wagner: Often referred to as the father of solid-state chemistry, Wagner's work on oxidation rate theory, counter diffusion of ions, and defect chemistry considerably advanced knowledge of how reactions proceed at the atomic level in the solid state. Wagner was the first recipient of the ECS Palladium Award in 1951.
*Irving Langmuir: received the 1932 Nobel Prize in Chemistry “for his discoveries and investigations in surface chemistry”.
*Edward Goodrich Acheson: The inventor of the Acheson process was a manufacturer of carborundum and graphite. The ECS Acheson Award was named in his honor in 1931.
*Theodore William Richards: Richards, whose research helped confirm the existence of isotopes, received the 1914 Nobel Prize in Chemistry, “in recognition of his accurate determinations of the atomic weight of a large number of chemical elements”.
*Willis R. Whitney: ECS president from 1911-1912, Whitney is most recognized among his many achievements for founding the research laboratory of the General Electric Company.
*Leo Baekeland: Baekland, who served as ECS president in 1909, is most famous for inventing Bakelite in 1907. His entrepreneurial genius and inventive nature made Baekeland one of the most important players in chemical technology.
*Herbert H. Dow: Among his most significant achievements, Dow founded the Dow Chemical Company in 1897. Dow Chemical funded the creation of the ECS Industrial Electrochemistry and Electrochemical Engineering Division H. H. Dow Memorial Student Achievement Award in his honor in 1990.
*Edward Weston: Noted for his achievements in electroplating, Weston developed the electrochemical cell – named the Weston cell, for the voltage standard.
*Charles Martin Hall: Hall, is best known for inventing an inexpensive process to produce aluminum, was one of the founders of Alcoa.
*Lawrence Addicks (1878-1964) served as president of The Electrochemical Society from 1915 to 1916. | 7 | Physical Chemistry |
The process typically takes place between 900 and 1100 °C, with an anode (typically carbon) and a cathode (the oxide being reduced) in a solution of molten CaCl. Depending on the nature of the oxide it will exist at a particular potential relative to the anode, which is dependent on the quantity of CaO present in CaCl. | 7 | Physical Chemistry |
* Cost of reactor and replacements (each replacement unit costs ~ $6000)
* Addition of dead volume causes an increase in peak broadening depending on the GC column flow rates and molecule types (5-10% broadening is typical)
** Heteroatoms and oxidation of Polyarc transfer lines increase this broadening
* Susceptible to sulfur, silicon, and halogen poisoning
* Requires constant feed of hydrogen
* Cannot be regenerated in-house; must be shipped back to the manufacturer for a replacement
* Cannot be used with cryogenic oven temperatures, or for GCxGC
* Poor response for species containing C-F bonds
* May contribute to power overload on older GC models, preventing the use of other heated components such as valve boxes or auxiliary detectors | 3 | Analytical Chemistry |
The protein encoded by this gene belongs to the immunoglobulin superfamily. It is a type I membrane protein. The protein may play a role in the adhesive interactions of activated T and NK cells during the late phase of the immune response. It may also function in antigen presentation. Alternative splicing generates multiple transcript variants encoding distinct isoforms. [provided by RefSeq, Jan 2016]. | 1 | Biochemistry |
Bromophenol blue (3′,3″,5′,5″-tetrabromophenolsulfonphthalein, BPB), albutest is used as a pH indicator, an electrophoretic color marker, and a dye. It can be prepared by slowly adding excess bromine to a hot solution of phenolsulfonphthalein in glacial acetic acid. | 3 | Analytical Chemistry |
It has been studied in AIDS-related Kaposis sarcoma, West Nile virus, and to inactivate Staphylococcus aureus', and HIV-1. Phenothiazine dyes and light have been known to have virucidal properties for over 70 years. | 3 | Analytical Chemistry |
As stated above, the STAT3-Ser/Hes3 signaling axis regulates the number of neural stem cells (as well as other cell types) in culture. This prompted experiments to determine if the same pathway can also regulate the number of naturally resident (endogenous) neural stem cells in the adult rodent brain. If so, this would generate a new experimental approach to study the effects of increasing the number of endogenous neural stem cells (eNSCs). For example, would this lead to the replacement of lost cells by newly generated cells from eNSCs? Or, could this lead to the rescue of damaged neurons in models of neurodegenerative disease, since eNSCs are known to produce factors that can protect injured neurons?
Various treatments that input into the STAT3-Ser/Hes3 signaling axis (Delta4, Angiopoietin 2, insulin, or a combined treatment consisting of all three factors and an inhibitor of JAK) induce the increase in numbers of endogenous neural stem cells as well as behavioral recovery in models of neurodegenerative disease. Several pieces of evidence suggest that in the adult brain, pharmacological activation of the STAT3-Ser/Hes3 signaling axis protects compromised neurons through increased neurotrophic support provided by activated neural stem cells / neural precursor cells, which can be identified by their expression of Hes3:
:* These treatments increase the number of Hes3+ cells by several-fold.
:* Hes3+ cells can be isolated and placed in culture where they exhibit stem cell properties.
:* In culture and in vivo, Hes3+ cells express Shh, which supports the survival of certain neurons [Hes3+ cells may also express other pro-survival factors, yet unidentified].
:* The distribution of Hes3+ cells in the adult brain is widespread and can be found in close physical proximity to different types of neurons.
:* Diverse treatments that converge to the STAT3-Ser/Hes3 signaling axis exert similar effects in the normal brain (increase in the number of Hes3+ cells) and in the compromised brain (increase in the number of Hes3+ cells, oppose neuronal death, and improve behavioral state).
:* Macrophage migration inhibitory factor stimulates this signaling pathway and promotes the survival of neural stem cells.
:* Mice genetically engineered to lack the Hes3 gene exhibit differences in the amount of myelin basic protein (a protein expressed on myelinating oligodendrocytes), relative to normal mice; Hes3-lacking mice also exhibit a different regulation of this protein after oligodendrocyte damage induced by the chemical cuprizone. | 1 | Biochemistry |
While earlier version of fiber-based laser traps exclusively used single mode beams, M. Kreysing and colleagues recently showed that the careful excitation of further optical modes in a short piece of optical fiber allows the realization of non-trivial trapping geometries. By this the researchers were able to orient various human cell types (individual cells and clusters) on a microscope. The main advantage of the so-called "optical cell rotator" technology over standard optical tweezers is the decoupling of trapping from imaging optics. This, its modular design, and the high compatibility of divergent laser traps with biological material indicates the great potential of this new generation of laser traps in medical research and life science. Recently, the optical cell rotator technology was implemented on the basis of adaptive optics, allowing to dynamically reconfigure the optical trap during operation and adapt it to the sample. | 1 | Biochemistry |
Regions of the short arm of chromosome 8 are frequently deleted in a range of solid tumors, indicating that tumor suppressor genes reside at these loci. Caldwell et al. have shown frequent interstitial deletions in a series of prostate cancers, squamous cell head and neck cancers and colorectal carcinomas. There was also an association between 8p11.2 deletion and local invasion.
The first coding exon contains the whole of the frizzled-related cysteine rich domain (CRD), while the third exon (COOH-terminal domain) contains the netrin-related domain. Netrin is a regulator of apoptosis; the SFRP1 netrin-related motif is also found in a range of other proteins that is thought to mediate protein-protein interactions. The middle exon most likely represents a spacer between the first and third exon. There are 2 introns present within the coding sequence of SFRP1. | 1 | Biochemistry |
CDI is mainly employed to convert amines into amides, carbamates, ureas. It can also be used to convert alcohols into esters. | 0 | Organic Chemistry |
Sedimentation equilibrium in a suspension of different particles, such as molecules, exists when the rate of transport of each material in any one direction due to sedimentation equals the rate of transport in the opposite direction due to diffusion. Sedimentation is due to an external force, such as gravity or centrifugal force in a centrifuge.
It was discovered for colloids by Jean Baptiste Perrin for which he received the Nobel Prize in Physics in 1926. | 1 | Biochemistry |
In the early 2020s, molecular biology entered a golden age defined by both vertical and horizontal technical development. Vertically, novel technologies are allowing for real-time monitoring of biological processes at the atomic level. Molecular biologists today have access to increasingly affordable sequencing data at increasingly higher depths, facilitating the development of novel genetic manipulation methods in new non-model organisms. Likewise, synthetic molecular biologists will drive the industrial production of small and macro molecules through the introduction of exogenous metabolic pathways in various prokaryotic and eukaryotic cell lines.
Horizontally, sequencing data is becoming more affordable and used in many different scientific fields. This will drive the development of industries in developing nations and increase accessibility to individual researchers. Likewise, CRISPR-Cas9 gene editing experiments can now be conceived and implemented by individuals for under $10,000 in novel organisms, which will drive the development of industrial and medical applications. | 1 | Biochemistry |
Hemorphin-4 is an endogenous opioid peptide of the hemorphin family which possesses antinociceptive properties and is derived from the β-chain of hemoglobin in the bloodstream. It is a tetrapeptide with the amino acid sequence Tyr-Pro-Trp-Thr. Hemorphin-4 has affinities for the μ-, δ-, and κ-opioid receptors that are in the same range as the structurally related β-casomorphins, although affinity to the κ-opioid receptor is markedly higher in comparison. It acts as an agonist at these sites. Hemorphin-4 also has inhibitory effects on angiotensin-converting enzyme (ACE), and as a result, may play a role in the regulation of blood pressure. Notably, inhibition of ACE also reduces enkephalin catabolism. | 1 | Biochemistry |
The concept of using reinforced lipids to inhibit lipid peroxidation has been tested in numerous cell and animal
models, including:
* Parkinson's disease (MPTP and a-Syn models in mice and rats)
* Huntington's disease (in mice)
* Alzheimer's disease (APP/PS1 and ALDH2 mouse models)
* Diabetic retinopathy (Akita mice)
* Age-related macular degeneration (light irradiation in rats, eye iron overload in mice)
* Atherosclerosis (Leiden mice) | 1 | Biochemistry |
Since cyclic AMP is a second messenger and plays vital role in cell signalling, it has been implicated in various disorders but not restricted to the roles given below: | 1 | Biochemistry |
Microautoradiography FISH is a technique to combine radio-labeled substrates with conventional FISH to detect phylogenetic groups and metabolic activities simultaneously. | 1 | Biochemistry |