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*Stefan Lovgren, [https://web.archive.org/web/20050319053238/http://news.nationalgeographic.com/news/2005/03/0318_050318_cryonics.html "Corpses Frozen for Future Rebirth by Arizona Company"], March 2005, National Geographic
1
Biochemistry
Fetal hemoglobin (HbF) is structurally different from normal adult hemoglobin (HbA), giving HbF a higher affinity for oxygen than HbA. HbF is composed of two alpha and two gamma chains whereas HbA is composed of two alpha and two beta chains. The fetal dissociation curve is shifted to the left relative to the curve for the normal adult because of these structural differences: In adult hemoglobin, the binding of 2,3-bisphosphoglycerate (2,3-BPG) primarily occurs with the beta chains, preventing the binding of oxygen with haemoglobin. This binding is crucial for stabilizing the deoxygenated state of hemoglobin, promoting the efficient release of oxygen to body tissues. In fetal hemoglobin, which possesses a gamma chain instead of a beta chain, the interaction with 2,3-BPG differes because 2,3 - -BPG not binds with gamma chain as it has lower to no affinity with gamma chain.This distinction contributes to fetal hemoglobin having a higher affinity for oxygen. Typically, fetal arterial oxygen pressures are lower than adult arterial oxygen pressures. Hence higher affinity to bind oxygen is required at lower levels of partial pressure in the fetus to allow diffusion of oxygen across the placenta. At the placenta, there is a higher concentration of 2,3-BPG formed, and 2,3-BPG binds readily to beta chains rather than to alpha chains. As a result, 2,3-BPG binds more strongly to adult hemoglobin, causing HbA to release more oxygen for uptake by the fetus, whose HbF is unaffected by the 2,3-BPG. HbF then delivers that bound oxygen to tissues that have even lower partial pressures where it can be released.
1
Biochemistry
After production in the upper atmosphere, the carbon-14 atoms react rapidly to form mostly (about 93%) (carbon monoxide), which subsequently oxidizes at a slower rate to form , radioactive carbon dioxide. The gas mixes rapidly and becomes evenly distributed throughout the atmosphere (the mixing timescale in the order of weeks). Carbon dioxide also dissolves in water and thus permeates the oceans, but at a slower rate. The atmospheric half-life for removal of has been estimated to be roughly 12 to 16 years in the northern hemisphere. The transfer between the ocean shallow layer and the large reservoir of bicarbonates in the ocean depths occurs at a limited rate. In 2009 the activity of was 238 Bq per kg carbon of fresh terrestrial biomatter, close to the values before atmospheric nuclear testing (226 Bq/kg C; 1950).
9
Geochemistry
Chiral drugs with stereo-labile configuration are likely to undergo interconversion of the enantiomers that may be enzymatic (biological) or non-enzymatic. Enzyme-mediated conversion is the process of chiral inversion that happens in a living organism. Non-enzymatic inversion of drugs is important and relevant in the pharmaceutical manufacturing process. This may have impact on the shelf-life of a drug and the economic feasibility of the resolution. Inversion can also happen without enzymes when precolumn derivatization is used in enantioselective chromatographic separation techniques. Racemization can also happen in the acidic environment of the stomach and other bodily fluids.
4
Stereochemistry
The Goldman–Hodgkin–Katz voltage equation, sometimes called the Goldman equation, is used in cell membrane physiology to determine the Resting potential across a cell's membrane, taking into account all of the ions that are permeant through that membrane. The discoverers of this are David E. Goldman of Columbia University, and the Medicine Nobel laureates Alan Lloyd Hodgkin and Bernard Katz.
7
Physical Chemistry
The Ferrier rearrangement is an organic reaction that involves a nucleophilic substitution reaction combined with an allylic shift in a glycal (a 2,3-unsaturated glycoside). It was discovered by the carbohydrate chemist Robert J. Ferrier.
0
Organic Chemistry
Electroforming is a metal forming process in which parts are fabricated through electrodeposition on a model, known in the industry as a mandrel. Conductive (metallic) mandrels are treated to create a mechanical parting layer, or are chemically passivated to limit electroform adhesion to the mandrel and thereby allow its subsequent separation. Non-conductive (glass, silicon, plastic) mandrels require the deposition of a conductive layer prior to electrodeposition. Such layers can be deposited chemically, or using vacuum deposition techniques (e.g., gold sputtering). The outer surface of the mandrel forms the inner surface of the form. The process involves passing direct current through an electrolyte containing salts of the metal being electroformed. The anode is the solid metal being electroformed, and the cathode is the mandrel, onto which the electroform gets plated (deposited). The process continues until the required electroform thickness is achieved. The mandrel is then either separated intact, melted away, or chemically dissolved. The surface of the finished part that was in intimate contact with the mandrel is replicated in fine detail with respect to the original, and is not subject to the shrinkage that would normally be experienced in a foundry cast metal object, or the tool marks of a milled part. The solution side of the part is less well defined, and that loss of definition increases with thickness of the deposit. In extreme cases, where a thickness of several millimetres is required, there is preferential build-up of material on sharp outside edges and corners. This tendency can be reduced by shielding, or a process known as periodic reverse, where the electroforming current is reversed for short periods and the excess is preferentially dissolved electrochemically. The finished form can either be the finished part, or can be used in a subsequent process to produce a positive of the original mandrel shape, such as with vinyl records or CD and DVD stamper manufacture. In recent years, due to its ability to replicate a mandrel surface with practically no loss of fidelity, electroforming has taken on new importance in the fabrication of micro and nano-scale metallic devices and in producing precision injection molds with micro- and nano-scale features for production of non-metallic micro-molded objects.
8
Metallurgy
Early work examined the dechlorinations with copper. Substrates included DDT, endrin, chloroform, and hexachlorocyclopentadiene. Aluminum and magnesium behave similarly in the laboratory. Ground water treatment most generally focuses on the use of iron.
2
Environmental Chemistry
* The monomer concentration is important for the synthesis of single chain cyclized/knotted polymers, but the kinetic chain length is the key determining factor for synthesis.
7
Physical Chemistry
The chemical composition of tall oil varies with the species of trees used in pulping, and in turn with geographical location. For example, the coastal areas of the southeastern United States have a high proportion of Slash Pine (Pinus elliottii); inland areas of the same region have a preponderance of Loblolly Pine (Pinus taeda). Slash Pine generally contains a higher concentration of resin acids than Loblolly Pine. In general, the tall oil produced in coastal areas of the southeastern United States contains over 40% resin acids and sometimes as much as 50% or more. The fatty acids fraction is usually lower than the resin acids, and unsaponifiables amount to 6-8%. Farther north in Virginia, where Pitch Pine (Pinus rigida)and Shortleaf Pine (Pinus echinata) are more dominant, the resin acid content decreases to as low as 30-35% with a corresponding increase in the fatty acids present. In Canada, where mills process Lodgepole Pine (Pinus contorta) in interior British Columbia and Alberta, Jack Pine (Pinus banksiana), Alberta to Quebec and Eastern White Pine (Pinus strobus) and Red Pine (Pinus resinosa), Ontario to New Brunswick, resin acid levels of 25% are common with unsaponifiable contents of 12-25%. Similar variations may be found in other parts of the United States and in other countries. For example, in Finland, Sweden and Russia, resin acid values from Scots Pine (Pinus sylvestris) may vary from 20 to 50%, fatty acids from 35 to 70%, and unsaponifiables from 6 to 30%.
1
Biochemistry
Obsidian hydration dating was introduced in 1960 by Irving Friedman and Robert Smith of the U.S. Geological Survey. Their initial work focused on obsidians from archaeological sites in western North America. The use of Secondary ion mass spectrometry (SIMS) in the measurement of obsidian hydration dating was introduced by two independent research teams in 2002. Today the technique is applied extensively by archaeologists to date prehistoric sites and sites from prehistory in California and the Great Basin of North America. It has also been applied in South America, the Middle East, the Pacific Islands, including New Zealand and Mediterranean Basin.
9
Geochemistry
Reactivity ratios indicate preference for propagation. Large indicates a tendency for to add , while small corresponds to a tendency for to add . Values of describe the tendency of to add or . From the definition of reactivity ratios, several special cases can be derived: * If both reactivity ratios are very high, the two monomers only react with themselves and not with each other. This leads to a mixture of two homopolymers. * . If both ratios are larger than 1, homopolymerization of each monomer is favored. However, in the event of crosspolymerization adding the other monomer, the chain-end will continue to add the new monomer and form a block copolymer. * . If both ratios are near 1, a given monomer will add the two monomers with comparable speeds and a statistical or random copolymer is formed. * If both values are near 0, the monomers are unable to homopolymerize. Each can add only the other resulting in an alternating polymer. For example, the copolymerization of maleic anhydride and styrene has reactivity ratios = 0.01 for maleic anhydride and = 0.02 for styrene. Maleic acid in fact does not homopolymerize in free radical polymerization, but will form an almost exclusively alternating copolymer with styrene. * In the initial stage of the copolymerization, monomer 1 is incorporated faster and the copolymer is rich in monomer 1. When this monomer gets depleted, more monomer 2 segments are added. This is called composition drift. * When both , the system has an azeotrope, where feed and copolymer composition are the same.
7
Physical Chemistry
The bottom part of ring B was constructed by nucleophilic addition to the aldehyde of 2.1 (scheme 2) with dibenzyl acetal of 2-bromobenzaldehyde 2.2 as its aryllithium. This step is much in common with the B ring synthesis in the Nicolaou Taxol total synthesis except that the aldehyde group is located at ring A and not ring B. The diol in 2.3 was protected as the boronic ester 2.4 preparing the molecule for upper part ring closure with tin tetrachloride to tricycle 2.5 in a Grob fragmentation-like reaction. After deprotection (pinacol) to diol 2.6, DIBAL reduction to triol 2.7 and TBS reprotection (TBSOtf, lutidine) to alcohol 2.8 it was possible to remove the phenylsulfide group in with a tributyltin hydride and AIBN(see Barton-McCombie deoxygenation) to alcohol 2.9. Palladium on carbon hydrogenation removed the benzyl protecting group allowing the Swern oxidation of 2.10 to ketone 2.11
0
Organic Chemistry
Two-component systems are rare in eukaryotes. They appear in yeasts, filamentous fungi, and slime molds, and are relatively common in plants, but have been described as "conspicuously absent" from animals. Two-component systems in eukaryotes likely originate from lateral gene transfer, often from endosymbiotic organelles, and are typically of the hybrid kinase phosphorelay type. For example, in the yeast Candida albicans, genes found in the nuclear genome likely originated from endosymbiosis and remain targeted to the mitochondria. Two-component systems are well-integrated into developmental signaling pathways in plants, but the genes probably originated from lateral gene transfer from chloroplasts. An example is the chloroplast sensor kinase (CSK) gene in Arabidopsis thaliana, derived from chloroplasts but now integrated into the nuclear genome. CSK function provides a redox-based regulatory system that couples photosynthesis to chloroplast gene expression; this observation has been described as a key prediction of the CoRR hypothesis, which aims to explain the retention of genes encoded by endosymbiotic organelles. It is unclear why canonical two-component systems are rare in eukaryotes, with many similar functions having been taken over by signaling systems based on serine, threonine, or tyrosine kinases; it has been speculated that the chemical instability of phosphoaspartate is responsible, and that increased stability is needed to transduce signals in the more complex eukaryotic cell. Notably, cross-talk between signaling mechanisms is very common in eukaryotic signaling systems but rare in bacterial two-component systems.
1
Biochemistry
Disabled Iranian veterans, called janbaz (, literally "those who were willing to lose their lives") in Iran, mostly constitute the disabled veterans of the Iran–Iraq war. According to Mohammad Esfandiari, director of communications and public relations of Irans Martyrs and Disabled Veterans Organization, there are 548,499 disabled veterans of the Iran–Iraq War living in Iran as of June 2014, a number which includes the victims of Iraqs chemical weapon attacks on Iran, called "chemical janbaz'" (). Among the disabled veterans are more than 10,000 veterans with foot and ankle injuries related to war.
1
Biochemistry
The oxygen effect is quantified by measuring the radiation sensitivity or Oxygen Enhancement Ratio (OER) of a particular biological effect (e.g., cell death or DNA damage), which is the ratio of doses under pure oxygen and anoxic conditions. Consequently, OER varies from unity in anoxia to a maximum value for 100% oxygen of typically up to three for low ionizing-density-radiation (beta-, gamma-, or x-rays), or so-called low linear energy transfer (LET) radiations. Radiosensitivity varies most rapidly for oxygen partial pressures below ~1% atmospheric (Fig. 1). Howard-Flanders and Alper (1957) developed a formula for the hyperbolic function of OER and its variation with oxygen concentration, or oxygen pressure in air. Radiobiologists identified additional characteristics of the oxygen effect that influence radiotherapy practices. They found that the maximum OER value diminishes as the ionizing-density of the radiation increases (Fig. 2), from low-LET to high-LET radiations. The OER is unity irrespective of the oxygen tension for alpha-particles of high-LET around 200 keV/μm. The OER is reduced for low doses as evaluated for cultured mammalian cells exposed to x-rays under aerobic (21% O2, 159 mmHg) and anoxic (nitrogen) conditions. Typical fractionation treatments are daily 2 Gy exposures, as below this dose the so-called shoulder or repair region of the cell survival curve is encroached upon reducing the OER (Fig. 3).
1
Biochemistry
Adenosine-to-Inosine (A-to-I) modifications were described well before the conception of epitranscriptomics. These modifications are very common in tissues and cells of the nervous system, and malfunctions in this deamination can result in a variety of different human diseases. A-to-I deamination has been shown to cause changes in the overall RNA structure or cause changes to the protein-coding mRNAs, although changes in codons and the amino acid they code for are not commonly seen. A-to-I RNA editing is described in more detail on the RNA editing page.
1
Biochemistry
In chemical reaction engineering, "yield", "conversion" and "selectivity" are terms used to describe ratios of how much of a reactant has reacted—conversion, how much of a desired product was formed—yield, and how much desired product was formed in ratio to the undesired product—selectivity, represented as X, S, and Y. According to the Elements of Chemical Reaction Engineering manual, yield refers to the amount of a specific product formed per mole of reactant consumed. In chemistry, mole is used to describe quantities of reactants and products in chemical reactions. The Compendium of Chemical Terminology defined yield as the "ratio expressing the efficiency of a mass conversion process. The yield coefficient is defined as the amount of cell mass (kg) or product formed (kg,mol) related to the consumed substrate (carbon or nitrogen source or oxygen in kg or moles) or to the intracellular ATP production (moles)." In the section "Calculations of yields in the monitoring of reactions" in the 1996 4th edition of Vogels Textbook of Practical Organic Chemistry (1978), the authors write that, "theoretical yield in an organic reaction is the weight of product which would be obtained if the reaction has proceeded to completion according to the chemical equation. The yield is the weight of the pure product which is isolated from the reaction." In the 1996 edition of Vogels Textbook', percentage yield is expressed as, According to the 1996 edition of Vogels Textbook, yields close to 100% are called quantitative, yields above 90% are called excellent, yields above 80% are very good, yields above 70% are good, yields above 50% are fair, and yields below 40% are called poor. In their 2002 publication, Petrucci, Harwood, and Herring wrote that Vogels Textbook names were arbitrary, and not universally accepted, and depending on the nature of the reaction in question, these expectations may be unrealistically high. Yields may appear to be 100% or above when products are impure, as the measured weight of the product will include the weight of any impurities. In their 2016 laboratory manual, Experimental Organic Chemistry, the authors described the "reaction yield" or "absolute yield" of a chemical reaction as the "amount of pure and dry product yielded in a reaction". They wrote that knowing the stoichiometry of a chemical reaction—the numbers and types of atoms in the reactants and products, in a balanced equation "make it possible to compare different elements through stoichiometric factors." Ratios obtained by these quantitative relationships are useful in data analysis.
0
Organic Chemistry
Observational longitudinal studies have further evaluated REMS T-score performance in the identification of patients at risk for fragility fracture. Specifically, in Adami et al., a group of more than 1.500 patients has undergone both DXA and REMS scans. Afterwards, these patients have been monitored for a period up to 5 years in order to estimate the incidence of fragility fractures in relationship with the T-score values previously obtained with both technologies. The study has demonstrated that REMS T-score is an effective parameter for the prediction of the occurrence of fragility fractures, leading the authors to positive conclusions about the effectiveness of REMS technology in the identification of patients at risk for osteoporotic fracture.
7
Physical Chemistry
Agents that transiently block MPT include the immune suppressant cyclosporin A (CsA); N-methyl-Val-4-cyclosporin A (MeValCsA), a non-immunosuppressant derivative of CsA; another non-immunosuppressive agent, NIM811, 2-aminoethoxydiphenyl borate (2-APB), bongkrekic acid and alisporivir (also known as Debio-025). TRO40303 is a newly synthetitised MPT blocker developed by Trophos company and currently is in Phase I clinical trial.
1
Biochemistry
It is well known that optical interference often is a major problem in laser-based gas spectroscopy. In conventional laser-based gas spectrometers, the optical interference originates from e.g. etalon-type interference effects in (or between) optical components and multi-pass gas cells. Throughout the years, great efforts have been devoted to handle this problem. Proper optical design is important to minimize interference from the beginning (e.g. by tilting optical components, avoiding transmissive optics and using anti-reflection coating), but interference patterns can not be completely avoided and are often difficult to separate from gas absorption. Since gas spectroscopy often involves measurement of small absorption fractions (down to 10), appropriate handling of interference is crucial. Utilised countermeasures include customized optical design, tailored laser modulation, mechanical dithering, signal post-processing, sample modulation, and baseline recording and interference subtraction. In the case of GASMAS, optical interference is particularly cumbersome. This is related to the severe speckle-type interference that originates from the interaction between laser light and highly scattering solid materials. Since this highly non-uniform interference is generated in same place as the utility signal, it cannot be removed by design. The optical properties of the porous material under study determines the interference pattern, and the level of interference is not seldom much stronger than actual gas absorption signals. Random mechanical dithering (e.g. laser beam dithering and/or sample rotation ) has been found effective in GASMAS. However, this approach converts stable interference into a random noise that must be averaged away, thus requiring longer acquisition times. Baseline recording and interference subtraction may be applicable in some GASMAS applications, as may other of the methods described above.
7
Physical Chemistry
Kinetic capillary electrophoresis or KCE is capillary electrophoresis of molecules that interact during electrophoresis. KCE was introduced and developed by Professor Sergey Krylov and his research group at York University, Toronto, Canada. It serves as a conceptual platform for development of homogeneous chemical affinity methods for studies of molecular interactions (measurements of binding and rate constants) and affinity purification (purification of known molecules and search for unknown molecules). Different KCE methods are designed by varying initial and boundary conditions – the way interacting molecules enter and exit the capillary. Several KCE methods were described: non-equilibrium capillary electrophoresis of the equilibrium mixtures (NECEEM), sweeping capillary electrophoresis (SweepCE), and plug-plug KCE (ppKCE).
7
Physical Chemistry
Cleanup for urban gasworks, usually smaller Victorian sites, has usually consisted of removing the worst material en masse to a landfill site away from town. Remediation of larger sites, such as industrial cokeworks, has required a more selective approach as the volumes and site values involved have been too large to justify simply carrying it away elsewhere. Bio-remediation, mechanically working the soil to expose it to air, sunlight and bacterial action, is a process which can be effective against tars, but not blue billy. Billy residues may require small-scale identification across the site and their separation. By such screening it has been possible to separate the worst of the wastes as one-thirtieth of the total, then to stabilise that within a cementitious matrix and produce a stable form which could be re-used on site.
2
Environmental Chemistry
As widely accepted as this statement might be, it should not be considered synonymous with a lack of metal objects, as it points out native copper was relatively abundant, particularly in the Great Lakes region. The latest glacial period had resulted in the scouring of copper bearing rocks. Once the ice retreated, these were readily available for use in a variety of sizes. Copper was shaped via cold hammering into objects from very early dates (Archaic period in the Great Lakes region: 8000–1000 BCE). There is also evidence of actual mining of copper veins (Old Copper Complex), but disagreement exists as to the dates. Extraction would have been extremely difficult. Hammerstones may have been used to break off pieces small enough to be worked. This labor-intensive process might have been eased by building a fire on top of the deposit, then quickly dousing the hot rock with water, creating small cracks. This process could be repeated to create more small cracks. The copper could then be cold-hammered into shape, which would make it brittle, or hammered and heated in an annealing process to avoid this. The final object would then have to be ground and sharpened using local sandstone. Numerous bars have also been found, possibly indicative of trade for which their shaping into a bar would also serve as proof of quality. Great Lake artifacts found in the Eastern Woodlands of North America seem to indicate there were widespread trading networks by 1000 BCE. Progressively the usage of copper for tools decreases with more jewelry and adornments being found. This is believed to be indicative of social changes to a more hierarchical society. Thousands of copper mining pits have been found along the lake shore of Lake Superior, and on Isle Royale. These pits may have been in use as far back as 8,000 years ago. This copper was mined and then made into objects such as heavy spear points and tools of all kinds. It was also made into mysterious crescent objects that some archaeologists believe were religious or ceremonial items. The crescents were too fragile for utilitarian use, and many have 28 or 29 notches along the inner edge, the approximate number of days in a lunar month.The Old Copper Culture mainly flourished in Ontario and Minnesota. However at least 50 Old Copper items, including spear points and ceremonial crescents have been discovered in Manitoba. A few more in Saskatchewan, and at least one, a crescent, has turned up in Alberta, 2,000 kilometres from its homeland in Ontario. It is most likely that these copper items arrived in the plains as trade goods rather than people of the Old Copper Culture moving into these new places. However from one excavated site in eastern Manitoba we can see that at least some people were moving northwest. At a site near Bissett archaeologists have found copper tools, weapons, and waste material of manufacture, along with a large nugget of raw copper. This site however was dated to around 4,000 years ago, a time of cooler climate when the boreal forest's treeline moved much further south. Though if these migrants moved with their metallurgy up the Winnipeg River at this time they may have continued onward, into Lake Winnipeg, and the Saskatchewan River system. This Old Copper Culture never became particularity advanced, and never discovered the principle of creating alloys. This means that many, though they could make metal objects and weapons, continued to use their flint tools, which could maintain a sharper edge for much longer. The unalloyed copper could simply not compete, and in the later days of the Old Copper Culture the metal was almost exclusively used for ceremonial items. However this Great Lake model as a unique source of copper and of copper technologies remaining somewhat static for over 6,000 years has recently come into some level of criticism, particularly since other deposits seem to have been available to ancient North Americans, even if much smaller.
8
Metallurgy
As one would expect, the majority of these images reveal large increases in turbidity in the regions where a hurricane has made landfall. The increases are primarily due to sediments that have been resuspended from the shallow bottom regions. In areas near shore some of the signal may also be due to sediments eroded from beaches as well as from sediment laden river plumes. In some cases a post-hurricane phytoplankton bloom due to increased nutrient availability may perhaps be detectable. The examination of the turbidity after the passing of a hurricane can have potentially many uses for coastal resource management including: * identifying regional "hot spots" where the erosion could be expected to be most severe * estimating the total sediment concentration that has been mobilized by the hurricane * determining the spatial extent of the sediment mobilization * identifying the extent and contribution of river plumes * assessing and predicting potential ecosystem impacts With regard to these uses, determining the regions of high turbidity will allow managers to best decide on response strategies as well as help ensure that post-hurricane resources are most effectively utilized.
3
Analytical Chemistry
In 1970, lithium was approved by the United States Food and Drug Administration (FDA) for the treatment of bipolar disorder, which remains its primary use in the United States. It is sometimes used when other treatments are not effective in a number of other conditions, including major depression, schizophrenia, disorders of impulse control, and some psychiatric disorders in children. Because the FDA has not approved lithium for the treatment of other disorders, such use is off-label.
1
Biochemistry
Khimera incorporates up to date achievements in the development of the wide range of models of elementary physicochemical processes; these models are of particular importance for hi-tech applications in: *microelectronics *materials science *chemical industry *automobile and aviation industry *power engineering.
7
Physical Chemistry
Another direction for transparent wood applications is as a high optical transmittance for optoelectronic devices as substrates in photovoltaic solar cells. Li and her colleagues at the KTH Royal Institute of Technology studied the high optical transmittance that makes transparent wood a candidate for substrate in perovskite solar cells. They concluded that transparent wood has high optical transmittance of 86% and long term stability with fracture of toughness 3.2 MPa⋅m compared to glass substrate fracture of toughness 0.7–0.85 MPa⋅m, which meets the substrates requirements for solar cells. These are relevant information for transparent woods possible application because it is a suitable and sustainable solution to the substrate for solar cell assembly with potential in energy-efficient building applications, as well as replacements for glass and lowering the carbon footprint for the devices. Transparent wood could transform the material sciences and building industries by enabling new applications such as load-bearing windows. These components could also generate improvements in energy savings and efficiency over glass or other traditional materials. A lot of work and research is needed to understand the interaction between light and the wood structure further, to tune the optical and mechanical properties, and to take advantage of advanced transparent wood composite applications
7
Physical Chemistry
Hydrogen bond-assisted supramolecular assembly is the process of assembling small organic molecules to form large supramolecular structures by non-covalent hydrogen bonding interactions. The directionality, reversibility, and strong bonding nature of hydrogen bond make it an attractive and useful approach in supramolecular assembly. Functional groups such as carboxylic acids, ureas, amines, and amides are commonly used to assemble higher order structures upon hydrogen bonding. Hydrogen bond play an essential role in the assembly of secondary and tertiary structures of large biomolecules. DNA double helix is formed by hydrogen bonding between nucleobases: adenine and thymine forms two hydrogen bonds, while guanine and cytosine forms three hydrogen bonds (Figure "Hydrogen bonds in (a) DNA duplex formation"). Another prominent example of hydrogen bond-assisted assembly in nature is the formation of protein secondary structures. Both the α-helix and β-sheet are formed through hydrogen bonding between the amide hydrogen and the amide carbonyl oxygen (Figure "Hydrogen bonds in (b) protein β-sheet structure"). In supramolecular chemistry, hydrogen bonds have been broadly applied to crystal engineering, molecular recognition, and catalysis. Hydrogen bonds are among the mostly used synthons in bottom-up approach to engineering molecular interactions in crystals. Representative hydrogen bond patterns for supramolecular assembly is shown in Figure "Representative hydrogen bond patterns in supramolecular assembly". A 1: 1 mixture of cyanuric acid and melamine forms crystal with a highly dense hydrogen-bonding network. This supramolecular aggregates has been used as templates to engineering other crystal structures.
6
Supramolecular Chemistry
STAT3 has been shown to interact with: * AR, * ELP2, * EP300, * EGFR, * HIF1A, * JAK1, * JUN * KHDRBS1, * mTOR, * MYOD1, * NDUFA13, * NFKB1, * NR3C1, * NCOA1, * PML, * RAC1, * RELA, * RET, * RPA2, * STAT1, * Stathmin, * Src, and * TRIP10. * KPNA4. Niclosamide seems to inhibit the STAT3 signalling pathway. Nicotinamide (a type of vitamin B) naturally inhibits STAT3. However NAC (Acetylcysteine) inhibits STAT3 inhibitors.
1
Biochemistry
The perturbative treatment of the Stark effect has some problems. In the presence of an electric field, states of atoms and molecules that were previously bound (square-integrable), become formally (non-square-integrable) resonances of finite width. These resonances may decay in finite time via field ionization. For low lying states and not too strong fields the decay times are so long, however, that for all practical purposes the system can be regarded as bound. For highly excited states and/or very strong fields ionization may have to be accounted for. (See also the article on the Rydberg atom).
7
Physical Chemistry
* Sherwood, L. (2004). Human Physiology From Cells to Systems, 5th Ed (p. 680). Belmont, CA: Brooks/Cole-Thomson Learning * Wilmore, J., Costill, D. (2004). Physiology of Sport and Exercise, 3rd Ed (p. 164). Champaign, IL: Human Kinetics
1
Biochemistry
2,3-Butanediol fermentation is anaerobic fermentation of glucose with 2,3-butanediol as one of the end products. The overall stoichiometry of the reaction is :2 pyruvate + NADH --> 2CO + 2,3-butanediol. Butanediol fermentation is typical for the facultative anaerobes Klebsiella and Enterobacter and is tested for using the Voges–Proskauer (VP) test. There are other alternative strains that can be used, talked about in details in the Alternative Bacteria Strains section below. The metabolic function of 2,3-butanediol is not known, although some have speculated that it was an evolutionary advantage for these microorganisms to produce a neutral product thats less inhibitory than other partial oxidation products and doesnt reduce the pH as much as mixed acids. There are many important industrial applications that butanediol can be used for, including antifreeze, food additives, antiseptic, and pharmaceuticals. It also is produced naturally in various places of the environment.
1
Biochemistry
An applied example is a synthesis of sunitinib begins by mixing 5-fluoroisatin slowly into hydrazine hydrate. After 4 hours at 110 °C, the indole ring structure has been broken into (2-amino-5-fluoro-phenyl)-acetic acid hydrazide with reduction of the ketone at the 3-position. Subsequent annelation in strong acid creates the 1,3-dihydro-2-oxo indole structure required for the drug.
0
Organic Chemistry
In general, a catalyst is an agent that increases the speed of a chemical reaction without being consumed by a reaction. Thermodynamically, a catalyst lowers the activation energy required for a chemical reaction to take place. An electrocatalyst is a catalyst that affects the activation energy of an electrochemical reaction. Shown below is the activation energy of chemical reactions as it relates to the energies of products and reactants. The activation energy in electrochemical processes is related to the potential, i.e. voltage, at which a reaction occurs. Thus, electrocatalysts frequently change the potential at which oxidation and reduction processes are observed. Alternatively, an electrocatalyst can be thought of as an agent that facilitates a specific chemical interaction at an electrode surface. Given that electrochemical reactions occur when electrons are passed from one chemical species to another, favorable interactions at an electrode surface increase the likelihood of electrochemical transformations occurring, thus reducing the potential required to achieve these transformations. Electrocatalysts can be evaluated according to three figures of merit: activity, stability, and selectivity. The activity of electrocatalysts can be assessed quantitatively by understanding how much current density is generated, and therefore how fast a reaction is taking place, for a given applied potential. This relationship is described with the Tafel equation. In assessing the stability of electrocatalysts, the ability of catalysts to withstand the potentials at which transformations are occurring is crucial. The selectivity of electrocatalysts refers to their preferential interaction with particular substrates, and their generation of a single product. Selectivity can be quantitatively assessed through a selectivity coefficient, which compares the response of the material to the desired analyte or substrate with the response to other interferents. In many electrochemical systems, including galvanic cells, fuel cells and various forms of electrolytic cells, a drawback is that they can suffer from high activation barriers. The energy diverted to overcome these activation barriers is transformed into heat. In most exothermic combustion reactions this heat would simply propagate the reaction catalytically. In a redox reaction, this heat is a useless byproduct lost to the system. The extra energy required to overcome kinetic barriers is usually described in terms of low faradaic efficiency and high overpotentials. In these systems, each of the two electrodes and its associated half-cell would require its own specialized electrocatalyst. Half-reactions involving multiple steps, multiple electron transfers, and the evolution or consumption of gases in their overall chemical transformations, will often have considerable kinetic barriers. Furthermore, there is often more than one possible reaction at the surface of an electrode. For example, during the electrolysis of water, the anode can oxidize water through a two electron process to hydrogen peroxide or a four electron process to oxygen. The presence of an electrocatalyst could facilitate either of the reaction pathways.
7
Physical Chemistry
The homing endonucleases are a collection of endonucleases encoded either as freestanding genes within introns, as fusions with host proteins, or as self-splicing inteins. They catalyze the hydrolysis of genomic DNA within the cells that synthesize them, but do so at very few, or even singular, locations. Repair of the hydrolyzed DNA by the host cell frequently results in the gene encoding the homing endonuclease having been copied into the cleavage site, hence the term homing to describe the movement of these genes. Homing endonucleases can thereby transmit their genes horizontally within a host population, increasing their allele frequency at greater than Mendelian rates.
1
Biochemistry
Isomers with a trigonal bipyramidal geometry are able to interconvert through a process known as Berry pseudorotation. Pseudorotation is similar in concept to the movement of a conformational diastereomer, though no full revolutions are completed. In the process of pseudorotation, two equatorial ligands (both of which have a shorter bond length than the third) "shift" toward the molecule's axis, while the axial ligands simultaneously "shift" toward the equator, creating a constant cyclical movement. Pseudorotation is particularly notable in simple molecules such as phosphorus pentafluoride (PF).
4
Stereochemistry
Monomers undergoing supramolecular polymerization are considered to be in equilibrium with the growing polymers, and thermodynamic factors therefore dominate the system. However, when the constituent monomers are connected via strong and multivalent interactions, a "metastable" kinetic state can dominate the polymerization. An externally supplied energy, in the form of heat in most cases, can transform the "metastable" state into a thermodynamically stable polymer. A clear understanding of multiple pathways exist in supramolecular polymerization is still under debate, however, the concept of "pathway complexity", introduced by E.W. "Bert" Meijer, shed a light on the kinetic behavior of supramolecular polymerization. Thereafter, many dedicated scientists are expanding the scope of "pathway complexity" because it can produce a variety of interesting assembled structures from the same monomeric units. Along this line of kinetically controlled processes, supramolecular polymers having "stimuli-responsive" and "thermally bisignate" characteristics is also possible. In conventional covalent polymerization, two models based on step-growth and chain-growth mechanisms are operative. Nowadays, a similar subdivision is acceptable for supramolecular polymerization; isodesmic also known as equal-K model (step-growth mechanism) and cooperative or nucleation-elongation model (chain-growth mechanism). A third category is seeded supramolecular polymerization, which can be considered as a special case of chain-growth mechanism.
6
Supramolecular Chemistry
An object's deflective efficiency can never equal or surpass 100%, for example: *a mirror will never reflect exactly the same amount of light cast upon it, though it may concentrate the light which is reflected into a narrower beam. *on hitting the ground, a ball previously in free-fall (meaning no force other than gravity acted upon it) will never bounce back up to the place where it first started to descend. This transfer of some energy into heat or other radiation is a consequence of the theory of thermodynamics, where, for every such interaction, some energy must be converted into alternative forms of energy or is absorbed by the deformation of the objects involved in the collision.
7
Physical Chemistry
The alpha-3 beta-2 nicotinic receptor, also known as the α3β2 receptor, is a type of nicotinic acetylcholine receptor, consisting of α3 and β2 subunits. It occurs alongside the more common α3β4 nicotinic receptor in autonomic ganglia, and as an facilitatory presynaptic autoreceptor at the neuromuscular junction (NMJ). At the NMJ, it is involved in upregulation of ACh release during high-frequency stimulation. Nicotine, a component of tobacco, a common stimulate of the receptor has been found to increase the concentration of this receptor. Blockage of this receptor in the presence of a partial postsynaptic neuromuscular block is thought to produce the characteristic tetanic fade caused by non-depolarizing neuromuscular blockers. The receptor is classified as an allosteric enzyme that is generally activated by the natural agonist acetylcholine, however it may also be activated by external agonists such as nicotine and blocked by toxins such as bungarus toxin 3.1. The main role of the receptor is to allow the re uptake of the neurotransmitter acetylcholine. Because it is a receptor involved in mechanisms including the neurotransmitter acetylcholine it is synthesized in the brain. However, α3β2 receptors synthesized in different locations of the brain may have differing regulatory properties. this is due to the cytoplasmic region in which the receptor is being formulated. Even though, there have been theories, how the increase in the receptors and uptaking of acetylcholine because of smoking nicotine can cause schizophrenia, no real correlation has been deducted.
1
Biochemistry
An ideal Bose gas is a quantum-mechanical phase of matter, analogous to a classical ideal gas. It is composed of bosons, which have an integer value of spin and abide by Bose–Einstein statistics. The statistical mechanics of bosons were developed by Satyendra Nath Bose for a photon gas and extended to massive particles by Albert Einstein, who realized that an ideal gas of bosons would form a condensate at a low enough temperature, unlike a classical ideal gas. This condensate is known as a Bose–Einstein condensate.
7
Physical Chemistry
Sandy soil has lower capacity to hold water and nutrients. Water is applied more frequently in smaller amounts to avoid it leaching and carrying nutrients below the root zone. Routine application of organic matter increases sandy soil's ability to hold water and nutrients by 10 times or more.
9
Geochemistry
DNA condensation refers to the process of compacting DNA molecules in vitro or in vivo. Mechanistic details of DNA packing are essential for its functioning in the process of gene regulation in living systems. Condensed DNA often has surprising properties, which one would not predict from classical concepts of dilute solutions. Therefore, DNA condensation in vitro serves as a model system for many processes of physics, biochemistry and biology. In addition, DNA condensation has many potential applications in medicine and biotechnology. DNA diameter is about 2 nm, while the length of a stretched single molecule may be up to several dozens of centimetres depending on the organism. Many features of the DNA double helix contribute to its large stiffness, including the mechanical properties of the sugar-phosphate backbone, electrostatic repulsion between phosphates (DNA bears on average one elementary negative charge per each 0.17 nm of the double helix), stacking interactions between the bases of each individual strand, and strand-strand interactions. DNA is one of the stiffest natural polymers, yet it is also one of the longest molecules. The persistence length of double-stranded DNA (dsDNA) is a measure of its stiffness or flexibility, which depends on the DNA sequence and the surrounding environment, including factors like salt concentration, pH, and temperature. Under physiological conditions (e.g., near-neutral pH and physiological salt concentrations), the persistence length of dsDNA is generally around 50 nm, which corresponds to approximately 150 base pairs. This means that at large distances DNA can be considered as a flexible rope, and on a short scale as a stiff rod. Like a garden hose, unpacked DNA would randomly occupy a much larger volume than when it is orderly packed. Mathematically, for a non-interacting flexible chain randomly diffusing in 3D, the end-to-end distance would scale as a square root of the polymer length. For real polymers such as DNA, this gives only a very rough estimate; what is important, is that the space available for the DNA in vivo is much smaller than the space that it would occupy in the case of a free diffusion in the solution. To cope with volume constraints, DNA can pack itself in the appropriate solution conditions with the help of ions and other molecules. Usually, DNA condensation is defined as "the collapse of extended DNA chains into compact, orderly particles containing only one or a few molecules". This definition applies to many situations in vitro and is also close to the definition of DNA condensation in bacteria as "adoption of relatively concentrated, compact state occupying a fraction of the volume available". In eukaryotes, the DNA size and the number of other participating players are much larger, and a DNA molecule forms millions of ordered nucleoprotein particles, the nucleosomes, which is just the first of many levels of DNA packing.
1
Biochemistry
In a medical laboratory, flocculation is the core principle used in various diagnostic tests, for example the rapid plasma reagin test.
8
Metallurgy
SPIKE was developed by Ron Shamir's computational biology group in cooperation with the group of Yosef Shiloh, an Israel Prize recipient for his research in systems biology, and the group of Karen Avraham, a leading researcher of human deafness, all from Tel Aviv University.
1
Biochemistry
Lovastatin is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase), an enzyme that catalyzes the conversion of HMG-CoA to mevalonate. Mevalonate is a required building block for cholesterol biosynthesis and lovastatin interferes with its production by acting as a reversible competitive inhibitor for HMG-CoA, which binds to the HMG-CoA reductase. Lovastatin is a prodrug, an inactive lactone in its native form, the gamma-lactone closed ring form in which it is administered, is hydrolysed in vivo to the β-hydroxy acid open ring form; which is the active form. Lovastatin and other statins have been studied for their chemopreventive and chemotherapeutic effects. No such effects were seen in the early studies. More recent investigations revealed some chemopreventive and therapeutic effects, for certain types of cancer, especially in combination of statins with other anticancer drugs. It is likely that these effect are mediated by the properties of statins to reduce proteasome activity, leading to an accumulation of cyclin-dependent kinase inhibitors p21 and p27, and to subsequent G-phase arrest, as seen in cells of different cancer lines.
0
Organic Chemistry
The synthesis of ring II was accomplished with a Fischer indole synthesis using phenylhydrazine 1 and acetophenone derivative acetoveratrone 2 (catalyst polyphosphoric acid) to give the 2-veratrylindole 3. The veratryl group not only blocks the 2-position for further electrophilic substitution but will also become part of the strychnine skeleton. A Mannich reaction with formaldehyde and dimethylamine) produced gramine 4. Alkylation with iodomethane gave an intermediate quaternary ammonium salt which reacted with sodium cyanide in a nucleophilic substitution to nitrile 5 and then in a reduction with lithium aluminium hydride to tryptamine 6. Amine-carbonyl condensation with ethyl glyoxylate give the imine 7. The reaction of this imine with TsCl in pyridine to the ring-closed N-tosyl compound 8 was described by Woodward as a concerted nucleophilic enamine attack and formally a Pictet–Spengler reaction. This compound should form as a diastereomeric pair but only one compound was found although which one was not investigated. Finally the newly formed double bond was reduced by sodium borohydride to indoline 9 with the C8 hydrogen atom approaching from the least hindered side (this proton is removed later on in the sequence and is of no importance).
0
Organic Chemistry
In the early 1950s, divers found the remains of a shipwreck in Cape Gelidonya, off the coast of Turkey. The remains included a substantial amount of copper oxhide ingot material: 34 in full, five in half, 12 corners, and of random fragments. Twenty-four full copper oxhide ingots have stamps on their centers—usually of a circle containing intersecting lines. These stamps were likely made when the metal was soft. In addition, the ship contained numerous complete and incomplete copper bun-shaped ingots, rectangular tin bars, and Cypriot agricultural tools made of scrap bronze. Radiocarbon dating of brushwood from the ship gives an approximate date of 1200 BC.
8
Metallurgy
The Danheiser annulation or Danheiser TMS-cyclopentene annulation is an organic reaction of an α,β-unsaturated ketone and a trialkylsilylallene (e.g., trimethylsilyl- or triisopropylsilyl-) in the presence of a Lewis Acid to give a trialkylsilylcyclopentene in a regiocontrolled annulation.
0
Organic Chemistry
At this point in the synthesis of Taxol, the material was a racemic mixture. To obtain the desired enantiomer, allylic alcohol 4.9 was acylated with (1S)-(−)-camphanic chloride and dimethylaminopyridine, giving two diastereomers. These were then separated using standard column chromatography. The desired enantiomer was then isolated when one of the separated disatereomers was treated with potassium bicarbonate in methanol.
0
Organic Chemistry
The reaction allows for alkylation of electron deficient heterocyclic species which is not possible with Friedel-Crafts chemistry. A method for alkylating electron deficient arenes, nucleophilic aromatic substitution, is also unavailable to electron deficient heterocycles as the ionic nucleophilic species used will deprotonate the heterocycle over acting as a nucleophile. Again, in contrast to nucleophilic aromatic substitution, the Minisci reaction does not require functionalisation of the arene, allowing for direct C-H functionalisation. Further to this, the generated alkyl radical species will not rearrange during the reaction in the way that alkyl fragments appended by Friedel-Crafts alkylation often will; meaning groups such as n-pentyl and cyclopropyl groups can be added unchanged. The alkyl radical is also a soft nucleophile and so is very unlikely to interact with any hard electrophiles (carbonyl species for example) already present on the heterocycle, which increases the functional group tolerance of the reaction. The reaction has been the subject of much research in recent years, with a focus placed on improved reactivity towards a greater variety of heterocycles, increasing the number of alkylating reagents that can be used, and employing milder oxidants and acids.
0
Organic Chemistry
Cavitand cages are formed by linking bowl-shaped organic molecules called cavitands. The two "bowls" are linked with organometallic complexes. In order for a cavitand cage to efficiently self-assemble, the following requirements must be met: The cavitand scaffold must be rigid, the incoming metal complex must impose cis geometry, and there must be enough preorganization in the structure such that the entropic barrier to create the cage can be overcome. The complexes used to assemble cavitand cages are square planar with one η2 ligand; this helps enforce the final geometry. Without cis geometry, only small oligomers will form. Self-assembly also requires a ligand exchange; weakly bound ions such as BF- and PF- promote assembly because they leave the complex so it can bind with the nitriles on the rest of the structure.
6
Supramolecular Chemistry
Most hormones initiate a cellular response by initially binding to either cell surface receptors or intracellular receptors. A cell may have several different receptors that recognize the same hormone but activate different signal transduction pathways, or a cell may have several different receptors that recognize different hormones and activate the same biochemical pathway. Receptors for most peptide as well as many eicosanoid hormones are embedded in the cell membrane as cell surface receptors, and the majority of these belong to the G protein-coupled receptor (GPCR) class of seven alpha helix transmembrane proteins. The interaction of hormone and receptor typically triggers a cascade of secondary effects within the cytoplasm of the cell, described as signal transduction, often involving phosphorylation or dephosphorylation of various other cytoplasmic proteins, changes in ion channel permeability, or increased concentrations of intracellular molecules that may act as secondary messengers (e.g., cyclic AMP). Some protein hormones also interact with intracellular receptors located in the cytoplasm or nucleus by an intracrine mechanism. For steroid or thyroid hormones, their receptors are located inside the cell within the cytoplasm of the target cell. These receptors belong to the nuclear receptor family of ligand-activated transcription factors. To bind their receptors, these hormones must first cross the cell membrane. They can do so because they are lipid-soluble. The combined hormone-receptor complex then moves across the nuclear membrane into the nucleus of the cell, where it binds to specific DNA sequences, regulating the expression of certain genes, and thereby increasing the levels of the proteins encoded by these genes. However, it has been shown that not all steroid receptors are located inside the cell. Some are associated with the plasma membrane.
1
Biochemistry
Signaling Gateway is a web portal dedicated to signaling pathways powered by the San Diego Supercomputer Center at the University of California, San Diego. It was initiated by a collaboration between the Alliance for Cellular Signaling and Nature. A primary feature is the Molecule Pages database.
1
Biochemistry
The dominant use of hexamethylenetetramine is in the production of solid (powder) or liquid phenolic resins and phenolic resin moulding compounds, in which it is added as a hardening component. These products are used as binders, e.g., in brake and clutch linings, abrasives, non-woven textiles, formed parts produced by moulding processes, and fireproof materials.
0
Organic Chemistry
Neuromelanin (NM) is a dark pigment found in the brain which is structurally related to melanin. It is a polymer of 5,6-dihydroxyindole monomers. Neuromelanin is found in large quantities in catecholaminergic cells of the substantia nigra pars compacta and locus coeruleus, giving a dark color to the structures.
1
Biochemistry
Captopril, sold under the brand name Capoten among others, is an angiotensin-converting enzyme (ACE) inhibitor used for the treatment of hypertension and some types of congestive heart failure. Captopril was the first oral ACE inhibitor found for the treatment of hypertension. It does not cause fatigue as associated with beta-blockers. Due to the adverse drug event of causing hyperkalemia, as seen with most ACE Inhibitors, the medication is usually paired with a diuretic. Captopril was patented in 1976 and approved for medical use in 1980.
4
Stereochemistry
Operando spectroscopy is widely applicable to heterogeneous catalysis, which is largely used in industrial chemistry. An example of operando methodology to monitor heterogeneous catalysis is the dehydrogenation of propane with molybdenum catalysts commonly used in industrial petroleum. Mo/SiO and Mo/AlO were studied with an operando setup involving EPR/UV-Vis, NMR/UV-Vis, and Raman. The study examined the solid molybdenum catalyst in real time. It was determined that the molybdenum catalyst exhibited propane dehydrogenation activity, but deactivated over time. The spectroscopic data showed that the most likely catalytic active state was in the production of propene. The deactivation of the catalyst was determined to be the result of coke formation and the irreversible formation of crystals, which were difficult to reduce back to . The dehydrogenation of propane can also be achieved with chromium catalysts, through the reduction of to . Propylene is one of the most important organic starting materials is used globally, particularly in the synthesis of various plastics. Therefore, the development of effective catalysts to produce propylene is of great interest. Operando spectroscopy is of great value to the further research and development of such catalysts.
7
Physical Chemistry
Like OCT, the early implementations of a/LCI relied on physically changing the optical path length (OPL) to control the depth in the sample from which data are acquired. However, it has been demonstrated that it is possible to use a Fourier domain implementation to yield depth resolution in a single data acquisition. A broadband light source is used to produce a spectrum of wavelengths at once, and the backscattered light is collected by a coherent optical fiber in the return path to capture different scattering angles simultaneously. Intensity is then measured via a spectrometer: a single frame from the spectrometer contains scattering intensity as a function of wavelength and angle. Finally the data is Fourier transformed on a line-by-line basis to generate scattering intensity as a function of OPL and angle. In the resulting image, the x axis represents the OPL and the y axis the angle of reflection, thus yielding a 2D map of reflection intensities. Using this method, the acquisition speed is limited only by the integration time of the spectrometer and can be as short at 20 ms. The same data that initially required tens of minutes to acquire can be acquired ~10 times faster.
7
Physical Chemistry
Inorganic ions in animals and plants are ions necessary for vital cellular activity. In body tissues, ions are also known as electrolytes, essential for the electrical activity needed to support muscle contractions and neuron activation. They contribute to osmotic pressure of body fluids as well as performing a number of other important functions. Below is a list of some of the most important ions for living things as well as examples of their functions: * Cacalcium ions are a component of bones and teeth. They also function as biological messengers, as do most of the ions listed below. (See Hypocalcaemia.) *Zn - zinc ions are found in very small concentrations in the body, and their main purpose is that of an antioxidant; the zinc ions act as antioxidants both generally and for liver specific pro-oxidants. Zinc ions can also act as an antioxidant-like stabilizer for some macro-molecules which bind zinc ions with high affinity, especially in cysteine-rich binding sites. These binding sites use these zinc ions as a stabilizer to protein folds, making these protein motifs more rigid in structure. These structures include zinc fingers, and have several different conformations. * Kpotassium ions' main function in animals is osmotic balance, particularly in the kidneys. (See Hypokalemia.) * Nasodium ions have a similar role to potassium ions. (See Sodium deficiency.) *Mn- manganese ions are seen being used as stabilizer for varying protein configurations. However, manganese ion overexposure is linked to several neurodegenerative diseases such as Parkinson's disease. * Mg magnesium ions are a component of chlorophyll. (See Magnesium deficiency (plants)) * Cl inability to transport chloride ions in humans manifests itself as cystic fibrosis (CF) * Carbonate| the shells of sea creatures are calcium carbonate. In blood approximately 85% of carbon dioxide, is converted into aqueous carbonate ions (an acidic solution), allowing a greater rate of transportation. *Co- cobalt ions are present in the human body in amounts from 1 to 2 mg. Cobalt is observed in the heart, liver, kidney, and spleen, and considerably smaller quantities in the pancreas, brain, and serum. Cobalt is a necessary component of vitamin B and a fundamental coenzyme of cell mitosis. Cobalt is crucial for amino acid formation and some proteins to create myelin sheath in nerve cells. Cobalt also plays a role in creating neurotransmitters, which are vital for proper function within the organism. * Phosphate|adenosine triphosphate (ATP) is a common molecule which stores energy in an accessible form. Bone is calcium phosphate. * Fe/Feas found in haemoglobin, the main oxygen carrying molecule has a central iron ion. * Nitrate| source of nitrogen in plants for the synthesis of proteins.
7
Physical Chemistry
A sperm bank will aim to provide donor sperm which is safe by checking and screening donors and of their semen. A sperm donor must generally meet specific requirements regarding age and medical history. Requirements for sperm donors are strictly enforced, as in a study of 24,040 potential sperm donors, only 5620, or 23.38% were eligible to donate their sperm. Sperm banks typically screen potential donors for a range of diseases and disorders, including genetic diseases, chromosomal abnormalities and sexually transmitted infections that may be transmitted through sperm. The screening procedure generally also includes a quarantine period, in which the samples are frozen and stored for at least six months after which the donor will be re-tested for the STIs. This is to ensure no new infections have been acquired or have developed during the period of donation. Providing the result is negative, the sperm samples can be released from quarantine and used in treatments. Common reasons for sperm rejection include suboptimal semen quality and STDs. Chromosomal abnormalities are also a cause for semen rejection, but are less common. Children conceived through sperm donation have a birth defect rate of almost a fifth compared with the general population. A sperm bank takes a number of steps to ensure the health and quality of the sperm which it supplies and it will inform customers of the checks which it undertakes, providing relevant information about individual donors. A sperm bank will usually guarantee the quality and number of motile sperm available in a sample after thawing. They will try to select men as donors who are particularly fertile and whose sperm will survive the freezing and thawing process. Samples are often sold as containing a particular number of motile sperm per milliliter, and different types of samples may be sold by a sperm bank for differing types of use, e.g. ICI or IUI. The sperm will be checked to ensure its fecundity and also to ensure that motile sperm will survive the freezing process. If a man is accepted onto the sperm banks program as a sperm donor, his sperm will be constantly monitored, the donor will be regularly checked for infectious diseases, and samples of his blood will be taken at regular intervals. A sperm bank may provide a donor with dietary supplements containing herbal or mineral substances such as maca, zinc, vitamin E and arginine which are designed to improve the quality and quantity of the donors semen, as well as reducing the refractory time (i.e. the time between viable ejaculations). All sperm is frozen in straws or vials and stored for as long as the sperm donor may and can maintain it. Donors are subject to tests for infectious diseases such as human immunoviruses HIV (HIV-1 and HIV-2), human T-cell lymphotropic viruses (HTLV-1 and HTLV-2), syphilis, chlamydia, gonorrhea, hepatitis B virus, hepatitis C virus, cytomegalovirus (CMV), Trypanosoma cruzi and malaria as well as hereditary diseases such as cystic fibrosis, Sickle cell anemia, Familial Mediterranean fever, Gauchers disease, thalassaemia, Tay–Sachs disease, Canavans disease, familial dysautonomia, congenital adrenal hyperplasia, carnitine transporter deficiency and Karyotyping 46XY. Karyotyping is not a requirement in either EU or the US but some sperm banks choose to test donors as an extra service to the customer. A sperm donor may also be required to produce their medical records and those of their family, often for several generations. A sperm sample is usually tested micro-biologically at the sperm bank before it is prepared for freezing and subsequent use. A sperm donor's blood group may also be registered to ensure compatibility with the recipient. Some sperm banks may disallow sexually active gay men from donating sperm due to the population's increased risk of HIV and hepatitis B. Modern sperm banks have also been known to screen out potential donors based on genetic conditions and family medical history.
1
Biochemistry
Serial analysis of gene expression (SAGE) was a development of EST methodology to increase the throughput of the tags generated and allow some quantitation of transcript abundance. cDNA is generated from the RNA but is then digested into 11 bp "tag" fragments using restriction enzymes that cut DNA at a specific sequence, and 11 base pairs along from that sequence. These cDNA tags are then joined head-to-tail into long strands (>500 bp) and sequenced using low-throughput, but long read-length methods such as Sanger sequencing. The sequences are then divided back into their original 11 bp tags using computer software in a process called deconvolution. If a high-quality reference genome is available, these tags may be matched to their corresponding gene in the genome. If a reference genome is unavailable, the tags can be directly used as diagnostic markers if found to be differentially expressed in a disease state. The cap analysis gene expression (CAGE) method is a variant of SAGE that sequences tags from the 5’ end of an mRNA transcript only. Therefore, the transcriptional start site of genes can be identified when the tags are aligned to a reference genome. Identifying gene start sites is of use for promoter analysis and for the cloning of full-length cDNAs. SAGE and CAGE methods produce information on more genes than was possible when sequencing single ESTs, but sample preparation and data analysis are typically more labour-intensive.
1
Biochemistry
It is common to represent polymers backbones, notably proteins, in internal coordinates; that is, a list of consecutive dihedral angles and bond lengths. However, some types of computational chemistry instead use cartesian coordinates. In computational structure optimization, some programs need to flip back and forth between these representations during their iterations. This task can dominate the calculation time. For processes with many iterations or with long chains, it can also introduce cumulative numerical inaccuracy. While all conversion algorithms produce mathematically identical results, they differ in speed and numerical accuracy.
4
Stereochemistry
To use electron affinities properly, it is essential to keep track of sign. For any reaction that releases energy, the change ΔE in total energy has a negative value and the reaction is called an exothermic process. Electron capture for almost all non-noble gas atoms involves the release of energy and thus is exothermic. The positive values that are listed in tables of E are amounts or magnitudes. It is the word "released" within the definition "energy released" that supplies the negative sign to ΔE. Confusion arises in mistaking E for a change in energy, ΔE, in which case the positive values listed in tables would be for an endo- not exo-thermic process. The relation between the two is E = −ΔE(attach). However, if the value assigned to E is negative, the negative sign implies a reversal of direction, and energy is required to attach an electron. In this case, the electron capture is an endothermic process and the relationship, E = −ΔE(attach) is still valid. Negative values typically arise for the capture of a second electron, but also for the nitrogen atom. The usual expression for calculating E when an electron is attached is This expression does follow the convention ΔX = X(final) − X(initial) since −ΔE = −(E(final) − E(initial)) = E(initial) − E(final). Equivalently, electron affinity can also be defined as the amount of energy required to detach an electron from the atom while it holds a single-excess-electron thus making the atom a negative ion, i.e. the energy change for the process :X → X + e If the same table is employed for the forward and reverse reactions, without switching signs, care must be taken to apply the correct definition to the corresponding direction, attachment (release) or detachment (require). Since almost all detachments (require +) an amount of energy listed on the table, those detachment reactions are endothermic, or ΔE(detach) > 0.
7
Physical Chemistry
So long as it is symmetric, we can easily think of the system as an iterated function map, a common method of representing a chaotic, dynamical system. Figure 7 shows one possible representation of the variables, with the first variable, , representing the angle around the disc at rebound and the second, , representing the impact/rebound angle relative to the disc. A subset of these two variables, called the invariant set will map onto themselves. This set, four members of which are shown in Figures 8 and 9, will be fractal, totally non-attracting and of measure zero. This is an interesting inversion of the more normally discussed chaotic systems in which the fractal invariant set is attracting and in fact comprises the basin[s] of attraction. Note that the totally non-attracting nature of the invariant set is another property of a hyperbolic chaotic scatterer. Each member of the invariant set can be modelled using symbolic dynamics: the trajectory is labelled based on each of the discs off of which it rebounds. The set of all such sequences form an uncountable set. For the four members shown in Figures 8 and 9, the symbolic dynamics will be as follows: Members of the stable manifold may be likewise represented, except each sequence will have a starting point. When you consider that a member of the invariant set must "fit" in the boundaries between two basins of attraction, it is apparent that, if perturbed, the trajectory may exit anywhere along the sequence. Thus it should also be apparent that an infinite number of alternating basins of all three "colours" will exist between any given boundary. Because of their unstable nature, it is difficult to access members of the invariant set or the stable manifold directly. The uncertainty exponent is ideally tailored to measure the fractal dimension of this type of system. Once again using the single impact parameter, b, we perform multiple trials with random impact parameters, perturbing them by a minute amount, , and counting how frequently the number of rebounds off the discs changes, that is, the uncertainty fraction. Note that even though the system is two dimensional, a single impact parameter is sufficient to measure the fractal dimension of the stable manifold. This is demonstrated in Figure 10, which shows the basins of attraction plotted as a function of a dual impact parameter, and . The stable manifold, which can be seen in the boundaries between the basins, is fractal along only one dimension. Figure 11 plots the uncertainty fraction, f, as a function of the uncertainty, for a simulated Gaspard–Rice system. The slope of the fitted curve returns the uncertainty exponent, , thus the box-counting dimension of the stable manifold is, . The invariant set is the intersection of the stable and unstable manifolds. Since the system is the same whether run forwards or backwards, the unstable manifold is simply the mirror image of the stable manifold and their fractal dimensions will be equal. On this basis we can calculate the fractal dimension of the invariant set: where D_s and D_u are the fractal dimensions of the stable and unstable manifolds, respectively and N=2 is the dimensionality of the system. The fractal dimension of the invariant set is D=1.24.
7
Physical Chemistry
Eating a variety of foods that contain potassium is the best way to get an adequate amount. Foods with high sources of potassium include kiwifruit, orange juice, potatoes, coconut, avocados, apricots, parsnips and turnips, although many other fruits, vegetables, legumes, and meats contain potassium. Common foods very high in potassium: * beans (white beans and others) * dark leafy greens (spinach, Swiss chard, and others) * baked potatoes * dried fruit (apricots, peaches, prunes, raisins; figs and dates) * baked squash * yogurt * fish (salmon) * avocado * nuts (pistachios, almonds, walnuts, etc.) * seeds (squash, pumpkin, sunflower) Foods containing the highest concentration: * dried herbs * sun dried tomatoes * cocoa solids * whey powder * paprika * yeast extract * rice bran * molasses * dry roasted soybeans
1
Biochemistry
The Phosphagen System (ATP-PCr) occurs in the cytosol (a gel-like substance) of the sarcoplasm of skeletal muscle, and in the myocyte's cytosolic compartment of the cytoplasm of cardiac and smooth muscle. During muscle contraction: :HO + ATP → H + ADP + P (Mg assisted, utilization of ATP for Muscle contraction by ATPase) :H + ADP + CP → ATP + Creatine (Mg assisted, catalyzed by creatine kinase, ATP is used again in the above reaction for continued muscle contraction) :2 ADP → ATP + AMP (catalyzed by adenylate kinase/myokinase when CP is depleted, ATP is again used for muscle contraction) Muscle at rest: :ATP + Creatine → ADP + CP + H (Mg assisted, catalyzed by creatine kinase) :ADP + P → ATP (during anaerobic glycolysis and oxidative phosphorylation) When the Phosphagen System has been depleted of phosphocreatine (creatine phosphate), the resulting AMP produced from the adenylate kinase (myokinase) reaction is primarily regulated by the Purine Nucleotide Cycle.
1
Biochemistry
Deuterium can be used to reinforce specific oxidation-vulnerable C-H bonds within essential or conditionally essential nutrients, such as certain amino acids, or polyunsaturated fatty acids (PUFA), making them more resistant to oxidative damage. Deuterated polyunsaturated fatty acids, such as linoleic acid, slow down the chain reaction of lipid peroxidation that damage living cells. Deuterated ethyl ester of linoleic acid (RT001), developed by Retrotope, is in a compassionate use trial in infantile neuroaxonal dystrophy and has successfully completed a Phase I/II trial in Friedreich's ataxia.
9
Geochemistry
The most commonly used surface modification protocols are plasma activation, wet chemical treatment, including grafting, and thin-film coating. Surface energy mimicking is a technique that enables merging the device manufacturing and surface modifications, including patterning, into a single processing step using a single device material. Many techniques can be used to enhance wetting. Surface treatments, such as corona treatment, plasma treatment and acid etching, can be used to increase the surface energy of the substrate. Additives can also be added to the liquid to decrease its surface tension. This technique is employed often in paint formulations to ensure that they will be evenly spread on a surface.
7
Physical Chemistry
Iron–sulfur proteins are proteins characterized by the presence of iron–sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states. Iron–sulfur clusters are found in a variety of metalloproteins, such as the ferredoxins, as well as NADH dehydrogenase, hydrogenases, coenzyme Q – cytochrome c reductase, succinate – coenzyme Q reductase and nitrogenase. Iron–sulfur clusters are best known for their role in the oxidation-reduction reactions of electron transport in mitochondria and chloroplasts. Both Complex I and Complex II of oxidative phosphorylation have multiple Fe–S clusters. They have many other functions including catalysis as illustrated by aconitase, generation of radicals as illustrated by SAM-dependent enzymes, and as sulfur donors in the biosynthesis of lipoic acid and biotin. Additionally, some Fe–S proteins regulate gene expression. Fe–S proteins are vulnerable to attack by biogenic nitric oxide, forming dinitrosyl iron complexes. In most Fe–S proteins, the terminal ligands on Fe are thiolate, but exceptions exist. The prevalence of these proteins on the metabolic pathways of most organisms leads to theories that iron–sulfur compounds had a significant role in the origin of life in the iron–sulfur world theory. In some instances Fe–S clusters are redox-inactive, but are proposed to have structural roles. Examples include endonuclease III and MutY.
7
Physical Chemistry
The first widescale use of VCIs can be traced to Shell's patent for dicyclohexylammonium nitrite (DICHAN), which was eventually commercialized as VPI 260.  DICHAN was used extensively by the US military to protect a wide variety of metallic components from corrosion via various delivery systems, VCI powder, VCI paper, VCI solution, VCI slushing compound, etc. Safety and health concerns as well as inherent limitations has led to the abandonment of DICHAN as a VCI. At present, commercial VCI compounds are typically salts of moderately strong bases and weak volatile acids.  The typical bases are amines and the acids are carbonic, nitrous and carboxylic.
8
Metallurgy
Usually, plastocyanin can be found in organisms that contain chlorophyll b and cyanobacteria, as well as algae that contain chlorophyll c. Plastocyanin has also been found in the diatom, Thalassiosira oceanica, which can be found in oceanic environments. It was surprising to find these organisms containing the protein plastocyanin because the concentration of copper dissolved in the ocean is usually low (between 0.4 – 50 nM). However, the concentration of copper in the oceans is comparatively higher compared to the concentrations of other metals such as zinc and iron. Other organisms that live in the ocean, such as phytoplankton, have adapted to where they do not need these low concentration metals (Fe and Zn) to facilitate photosynthesis and grow.
5
Photochemistry
The general goal of the technique is similar to the DNA microarray. However, SAGE sampling is based on sequencing mRNA output, not on hybridization of mRNA output to probes, so transcription levels are measured more quantitatively than by microarray. In addition, the mRNA sequences do not need to be known a priori, so genes or gene variants which are not known can be discovered. Microarray experiments are much cheaper to perform, so large-scale studies do not typically use SAGE. Quantifying gene expressions is more exact in SAGE because it involves directly counting the number of transcripts whereas spot intensities in microarrays fall in non-discrete gradients and are prone to background noise.
1
Biochemistry
Many alloys of industrial significance have some volume fraction of second phase particles, either as a result of impurities or from deliberate alloying additions. Depending on their size and distribution such particles may act to either encourage or retard recrystallization.
8
Metallurgy
Early studies suggested a minimum of two RNAPs: one which synthesized rRNA in the nucleolus, and one which synthesized other RNA in the nucleoplasm, part of the nucleus but outside the nucleolus. In 1969, biochemists Robert G. Roeder and William Rutter discovered there are total three distinct nuclear RNA polymerases, an additional RNAP that was responsible for transcription of some kind of RNA in the nucleoplasm. The finding was obtained by the use of ion-exchange chromatography via DEAE coated Sephadex beads. The technique separated the enzymes by the order of the corresponding elutions, Ι,ΙΙ,ΙΙΙ, by increasing the concentration of ammonium sulfate. The enzymes were named according to the order of the elutions, RNAP I, RNAP II, RNAP IΙI. This discovery demonstrated that there was an additional enzyme present in the nucleoplasm, which allowed for the differentiation between RNAP II and RNAP III. RNA polymerase II (RNAP2) undergoes regulated transcriptional pausing during early elongation. Various studies has shown that disruption of transcription elongation is implicated in cancer, neurodegeneration, HIV latency etc.
1
Biochemistry
Imidazoline is a class of heterocycles formally derived from imidazoles by the reduction of one of the two double bonds. Three isomers are known, 2-imidazolines, 3-imidazolines, and 4-imidazolines. The 2- and 3-imidazolines contain an imine center, whereas the 4-imidazolines contain an alkene group. The 2-Imidazoline group occurs in several drugs.
0
Organic Chemistry
The pzc is the same as the isoelectric point (iep) if there is no adsorption of other ions than the potential determining H/OH at the surface. This is often the case for pure ("pristine surface") oxides in water. In the presence of specific adsorption, pzc and isoelectric point generally have different values.
7
Physical Chemistry
The entropy due to a set of states that can be either occupied with probability or empty with probability can be written as: where is Boltzmann constant. For a continuously distributed set of states as a function of energy, such as the eigenstates in an electronic band structure, the above sum can be written as an integral over the possible energy values, rather than a sum. Switching from summing over individual states to integrating over energy levels, the entropy can be written as: where is the density of states of the solid. The probability of occupation of each eigenstate is given by the Fermi function, : where is the Fermi energy and is the absolute temperature. One can then re-write the entropy as: This is the general formulation of the density-of-states based electronic entropy.
7
Physical Chemistry
Levobupivacaine has become a more favourable alternative for regional anaesthesia than bupivacaine due to its reduced toxicity. A plethora of non-human studies have established levobupivacaine’s lower risk of cardiac and neurotoxic adverse effects. Most animal studies show that the lethal dose (LD) of levobupivacaine is approximately 50% higher than that of bupivacaine. In general, laevorotatory isomers tend to cause significantly fewer adverse effects and are thus a safer pharmacological alternative. Levobupivacaine has a 97% protein binding rate which is 2% higher than what is observed in bupivacaine. The faster protein binding rate contributes to its reduced toxicity level. In human volunteer studies, levobupivacaine consistently proved to have a safety advantage over bupivacaine. Risk factors for local anaesthetic toxicity depend on the administration of levobupivacaine to myocardial and cerebral tissue, as well as the predisposition of these tissues to levobupivacaine’s negative effects. Age is a relevant factor in vulnerability to levobupivacaine toxicity. Elderly patients are more likely to have pre-existing conditions impacting the cardiac, renal and hepatic systems, which contribute to the slower absorption rate and plasma concentrations below the toxic level compared to younger patients. On the other hand, homeostatic disbalance can exacerbate toxic effects. It is important to adjust the dosage of levobupivacaine in paediatric patients due to their underdeveloped metabolic processing to prevent reaching toxic levels. The dosage of local anaesthetics is calculated based on the patient’s weight and body mass index, however, the association power is stronger in children than in adults. Moreover, symptoms of systemic toxicity like paraesthesia are harder to notice in children.
4
Stereochemistry
Boron porphyrins are a variety of porphyrin, a common macrocycle used for photosensitization and metal trapping applications, that incorporate boron. The central four nitrogen atoms in a porphyrin macrocycle form a unique molecular pocket which is known to accommodate transition metals of various sizes and oxidation states. Due to the diversity of binding modes available to porphyrin, there is a growing interest in introducing other elements (i.e. main group elements) into this pocket. Boron in particular has been shown to prefer binding to porphyrin in a 2:1 stoichiometry, primarily due to its small atomic radius, but the Group XIII element will bind in a 1:1 ratio with corrole, a macromolecule with a structure similar to porphyrin but with a smaller N pocket. Boron porphyrins are of interest because of the unique geometric environment to which both boron and porphyrin are subjected upon B-N bond formation. These new geometric motifs lead to novel reactivity, one of the most surprising examples being sterically-induced reductive coupling. Possible applications for boron porphyrins include BNCT delivery agents and OLED devices. Also of interest are molecules containing both boron and porphyrin moieties, but without B-N bonds. Examples include diketonate-porphyrin compounds and dyads (two-component molecules) containing the classic BODIPY dye.
5
Photochemistry
Downregulation of glycine-N-methyltransferase has been linked to hepatocellular carcinoma and pancreatic cancer. Serving this as a reliable marker for oncogenesis. When compared to patients with deletions in GNMT, patients with no deletions early-stage pancreatic cancer had twice the median months overall survival.
1
Biochemistry
MIKES, as the name implies, is used for kinetic energy spectrometery. This means that certain criteria are needed to accomplish this. One such feature of MIKES is that it has high kinetic energy resolution and good angular resolution. This is due to the fact that MIKES has low accelerating voltage, around 3 kilo-volts. Another feature is that it has good differential pumping between the various regions of the instrument. In addition, MIKES has multiple systems for bringing in and/or overseeing collision gases or vapors and the ability to vary slit height and width. This prevents favoritism when determining kinetic energy distributions. Although common now, back in the 1970s, MIKES had a great computer compatibility that allowed for readily obtainable molecular structures.
7
Physical Chemistry
The effects and influences of RE1/NRSE and REST/NRSF are significant in non-neuronal cells that require the repression or silencing of neuronal genes. These silencer elements also regulate the expression of genes that do not induce neuron-specific proteins and studies have shown the extensive impact these factors have in cellular processes. In Xenopus laevis, RE1/NRSE and REST/NRSF dysfunction or mutation demonstrated significant impact on neural tube, cranial ganglia, and eye development. All of these alterations can be traced to an improper patterning of the ectoderm during Xenopus development. Thus, a mutation or alteration in either the silencing region RE1/NRSE or silencer REST/NRSF factor can disrupt the proper differentiation and specification of the neuroepithelial domain and also hinder the formation of skin or ectoderm. The lack of these factors result in a decreased production of bone morphogenetic protein (BMP), which translates into a deficient development of the neural crest. Hence, the effects of NRSE and NRSF are of fundamental importance for neurogenesis of the developing embryo, and also in the early stages of ectodermal patterning. Ultimately, inadequate functioning of these factors can result in aberrant neural tube, cranial ganglia, and eye development in Xenopus.
1
Biochemistry
If the superspots are located at simple fractions of the vectors of the reciprocal lattice of the substructure, e.g., at q=(½,0,0), the resulting broken symmetry is a multiple of the unit cell along that axis. Such a modulation is called a commensurate superstructure.
3
Analytical Chemistry
The equation of state given here (PV = nRT) applies only to an ideal gas, or as an approximation to a real gas that behaves sufficiently like an ideal gas. There are in fact many different forms of the equation of state. Since the ideal gas law neglects both molecular size and intermolecular attractions, it is most accurate for monatomic gases at high temperatures and low pressures. The neglect of molecular size becomes less important for lower densities, i.e. for larger volumes at lower pressures, because the average distance between adjacent molecules becomes much larger than the molecular size. The relative importance of intermolecular attractions diminishes with increasing thermal kinetic energy, i.e., with increasing temperatures. More detailed equations of state, such as the van der Waals equation, account for deviations from ideality caused by molecular size and intermolecular forces.
7
Physical Chemistry
For the process of extracting the DNA/RNA, there are a number of essential guidelines. This includes a description of the extraction process done, a statement on what DNA extraction kit was used and any changes made to the directions, details on whether any DNase or RNase treatment was used, a statement on whether any contamination was assessed, a quantification of the amount of genetic material extracted, a description of the instruments used for the extraction, the methods used to retain RNA integrity, a statement on the RNA integrity number and quality indicator and the quantification cycle (Cq) reached, and lastly what testing was done to determine the presence or absence of inhibitors. Four desired pieces of information are where the reagents used were obtained from, what level of genetic purity was obtained, what yield was obtained, and an electrophoresis gel image for confirmation.
1
Biochemistry
Along with other aggregates, a hollow, spherical structure self-assembles from approximately 1,165 Mo wheels. This was termed a vesicle by analogy with lipid vesicles. Unlike lipid vesicles that are stabilised by hydrophobic interactions it is believed that the vesicle is stabilised by an interplay of van der Waals attraction, long-range electrostatic repulsion with further stabilization arising from hydrogen bonding involving water molecules encapsulated between the wheel-shaped clusters and in the vesicles' interior. The radius of the vesicle is 45 nm.
7
Physical Chemistry
Surface plasmon resonance can be implemented in analytical instrumentation. SPR instruments consist of a light source, an input scheme, a prism with analyte interface, a detector, and computer.
7
Physical Chemistry
Ste5 is involved in the following biological processes: *Invasive growth in response to glucose limitation *Negative regulation of the MAPK cascade *Pheromone-dependent signal transduction involved in conjugation with cellular fusion *Positive regulation of protein phosphorylation *Regulation of RNA-mediated transposition
1
Biochemistry
Emulsified Fuels are emulsions composed of water and a combustible liquid, either oil or a fuel. Emulsions are a particular example of a dispersion comprising a continuous and a dispersed phase. The most commonly used emulsion fuel is water-in-diesel emulsion. In the case of emulsions, both phases are the immiscible liquids, oil and water. Emulsion fuels can be either a microemulsion or an ordinary emulsion (sometimes referred to as macroemulsion, to differentiate it from microemulsion). The essential differences between the two are stability (microemulsions are thermodynamically stable systems, whereas macroemulsions are kinetically stabilized) and particle size distribution (microemulsions are formed spontaneously and have dimensions of 10 to 200 nm, whereas macroemulsions are formed by a shearing process and have dimensions of 100 nm to over 1 micrometer). Microemulsions are isotropic whereas macroemulsions are prone to settling (or creaming) and changes in particle size over time. Both use surfactants (also called emulsifiers) and can be either water-in-oil (invert emulsions), or oil-in-water (regular emulsions) or bicontinuous (also called multiple or complex emulsions).
7
Physical Chemistry
The Cassie–Baxter wetting regime also explains the water repellent features of the pennae (feathers) of a bird. The feather consists of a topography network of barbs and barbules and a droplet that is deposited on a these resides in a solid-liquid-air non-wetting composite state, where tiny air pockets are trapped within.
7
Physical Chemistry
This spectroscopic technique complements another recently developed method of chemical characterisation or fingerprinting, namely micro-thermal analysis (micro-TA). This also uses an “active” SThM probe, which acts as a heater as well as a thermometer, so as to inject evanescent temperature waves into a sample and to allow sub-surface imaging of polymers and other materials. The sub-surface detail detected corresponds to variations in heat capacity or thermal conductivity. Ramping the temperature of the probe, and thus the temperature of the small sample region in contact with it, allows localized thermal analysis and/or thermomechanometry to be performed.
7
Physical Chemistry
Coordination polymerization is a chain polymerization that involves the preliminary coordination of a monomer molecule with a chain carrier. The monomer is first coordinated with the transition metal active center, and then the activated monomer is inserted into the transition metal-carbon bond for chain growth. In some cases, coordination polymerization is also called insertion polymerization or complexing polymerization. Advanced coordination polymerizations can control the tacticity, molecular weight and PDI of the polymer effectively. In addition, the racemic mixture of the chiral metallocene can be separated into its enantiomers. The oligomerization reaction produces an optically active branched olefin using an optically active catalyst.
7
Physical Chemistry
Various neurotrophic factors such as BDNF and mesencephalic astrocyte-derived neurotrophic factor have been shown to be modulated by various mood stabilizers.
1
Biochemistry
Given 3 faces of a polyhedron which meet at a common vertex P and have edges AP, BP and CP, the cosine of the dihedral angle between the faces containing APC and BPC is: This can be deduced from Spherical law of cosines
4
Stereochemistry
BBE-like enzymes in plant physiology play a role in primary metabolism catalyzed by members of this family. The oxidation of a variety of alcohol groups supplies a first understanding of the origin of the BBE-like enzyme family, present in reactions like oxidation of mono and polysaccharides. It seems that they are present in a huge percentage of plants. A common reaction of BBE-like enzymes from plants is the oxidation of carbohydrates at the anomeric center to the appropriate lactones. A member of these enzymes is hexose oxidase (HOX) from Chondrus crispus, a red algae that belongs to the division of Rhodophyta. But is more related to bacterial BBE-like enzymes than to members present in plants. Other example of carbohydrate oxidizing BBE-like enzyme is nectarin V (Nec5) from tobacco. Its function is to convert glucose to gluconolactone. Nec5 is related with the pathogen defense system of plants, because it protects reproductive organelles. Another function of this class of enzymes in plants is Defense response homeostasis. BBE-like enzymes play a key role as oligosaccharide oxidases, reducing the activity of olygogalacturonanes (fragments of pectin) and oligocellobiose (fragments of cellulose) as DAMPS.
1
Biochemistry
The number of adatoms present on a surface is temperature dependent. The relationship between the surface adatom concentration and the temperature at equilibrium is described by equation 4, where n is the total number of surface sites per unit area: This can be extended to find the equilibrium concentration of other types of surface point defects as well. To do so, the energy of the defect in question is simply substituted into the above equation in the place of the energy of adatom formation.
7
Physical Chemistry
An organic superconductor is a synthetic organic compound that exhibits superconductivity at low temperatures. As of 2007 the highest achieved critical temperature for an organic superconductor at standard pressure is , observed in the alkali-doped fullerene RbCsC. In 1979 Klaus Bechgaard synthesized the first organic superconductor (TMTSF)PF (the corresponding material class was named after him later) with a transition temperature of T = 0.9 K, at an external pressure of 11 kbar. Many materials may be characterized as organic superconductors. These include the Bechgaard salts and Fabre salts which are both quasi-one-dimensional, and quasi-two-dimensional materials such as k-BEDT-TTFX charge-transfer complex, λ-BETSX compounds, graphite intercalation compounds and three-dimensional materials such as the alkali-doped fullerenes. Organic superconductors are of special interest not only for scientists, looking for room-temperature superconductivity and for model systems explaining the origin of superconductivity but also for daily life issues as organic compounds are mainly built of carbon and hydrogen which belong to the most common elements on earth in contrast to copper or osmium.
0
Organic Chemistry
Colloid vibration current is an electroacoustic phenomenon that arises when ultrasound propagates through a fluid that contains ions and either solid particles or emulsion droplets. The pressure gradient in an ultrasonic wave moves particles relative to the fluid. This motion disturbs the double layer that exists at the particle-fluid interface. The picture illustrates the mechanism of this distortion. Practically all particles in fluids carry a surface charge. This surface charge is screened with an equally charged diffuse layer; this structure is called the double layer. Ions of the diffuse layer are located in the fluid and can move with the fluid. Fluid motion relative to the particle drags these diffuse ions in the direction of one or the other of the particle's poles. The picture shows ions dragged towards the left hand pole. As a result of this drag, there is an excess of negative ions in the vicinity of the left hand pole and an excess of positive surface charge at the right hand pole. As a result of this charge excess, particles gain a dipole moment. These dipole moments generate an electric field that in turn generates measurable electric current. This phenomenon is widely used for measuring zeta potential in concentrated colloids.
7
Physical Chemistry
The process of histamine inactivation in biological species involves its metabolism through the oxidative deamination of its primary amino group. This reaction is catalyzed by the enzyme diamine oxidase (DAO). The metabolite produced from this reaction is imidazole-4-acetaldehyde. Imidazole-4-acetaldehyde is then further oxidized by a NAD-dependent aldehyde dehydrogenase, leading to imidazole-4-acetic acid.
1
Biochemistry