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Fermented water contains a similar alcoholic content of wines as both beverages are fermented on yeast, however fermented water differs from wine and other fermented beverages in that it contains no fruit juice or residual sugar after manufacture.
Kilju can be produced by fermenting sugar, yeast, and water, but it was illegal in Finland before March 2018; therefore, grain, potatoes, fruits or berries were used during fermentation to avoid legal problems and to flavor the drink. Oranges and lemons are a popular choice for this purpose. | 1 | Biochemistry |
Lithium amides are usually prepared in the laboratory through the addition of a titrated solution of n-butyllithium in hexanes to a solution of the amine in ether. Dry glassware and inert atmosphere are required for these reactions. Alternatively, lithium amides may be prepared by the direct action of lithium on the corresponding amine. Typical temperatures for isomerization reactions employing lithium amides are between 0 °C and reflux (ether/hexane solvent mixtures derived from the synthesis of the lithium amide are usually used directly for isomerization reactions). An excess of the base is employed to account for impurities that consume base and reaction of the base with the ether solvent. Care should be taken when HMPA is added to lithium amide reactions, as it is a known animal carcinogen.
Organolithium reagents may also be used; however, lower temperatures are required to avoid decomposition of the base. These reactions are most often run in hexanes.
Aluminum amides, which are bulkier and sometimes more selective than lithium amides, are prepared from the corresponding lithium amides and diethylaluminum chloride. Reactions are usually carried out at 0 °C in an inert atmosphere, with benzene as the solvent. | 0 | Organic Chemistry |
The Gaussian line shape has the standardized form,
The subsidiary variable, x, is defined in the same way as for a Lorentzian shape. Both this function and the Lorentzian have a maximum value of 1 at x = 0 and a value of 1/2 at x=±1. | 7 | Physical Chemistry |
Beta oxidation removes 2 carbons at a time, so in the oxidation of an 18 carbon fatty acid such as Stearic Acid 8 cycles will need to occur to completely break down Acyl-CoA. This will produce 9 Acetyl-CoA that have 2 carbons each, 8 FADH2, and 8 NADH. | 1 | Biochemistry |
Yttria-alumina melts are another system reported to exhibit polyamorphism. Observation of a liquid–liquid phase transition in the supercooled liquid has been reported. Though this is disputed in the literature. Polyamorphism has also been reported in Yttria-Alumina glasses. Yttria-Alumina melts quenched from about 1900 °C at a rate ~400 °C/s, can form glasses containing a second co-existing phase. This happens for certain Y/Al ratios (about 20–40 mol% YO). The two phases have the same average composition but different density, molecular structure and hardness. However whether the second phase is glassy or crystalline is also debated.
Continuous changes in density were observed upon cooling silicon dioxide or germanium dioxide. Although continuous density changes do not constitute a first order transition, they may be indicative of an underlying abrupt transition. | 7 | Physical Chemistry |
In E. coli, it has been shown that an inducible, periplasmic TMAO reductase is responsible for almost all TMAO reduction (with the rest being DMSO reduction). While no structural analysis of this E. coli enzyme has been reported, TMAO reductase from Shewanella massilia has been isolated and characterized at a resolution of 2.5 Å.
TMAO reductases have been studied in several organisms, and a common feature is the presence of a molybdenum cofactor in all the known terminal enzymes. The common form of the molybdopterin molecule is a tricyclic ring system comprising a pterin group fused to a pyran ring. The role of this pyran ring could be a way of controlling the oxidation state of the molybdenum cofactor and/or facilitating proton diffusion. Furthermore, the arrangement of aromatic residues in the funnel-like entrance leading to the active center is closely related to that of DMSO reductase structures. A hydrophobic pocket, formed by two tryptophan and two tyrosine residues, is also present in the TMAO reductase and contains highly conserved residues.
When comparing TMAO reductase of S. massilia to DMSO reductase from R. Sphaeroides and R. capsulatus, the overall structure is strikingly similar. However, one major difference in TMAO reductase is a missing tyrosine (Tyr114), in DMSO reductase of R. capsulatus. It is replaced by a threonine (Thr116) in the TMAO reductase, and the backbone stretch around this residue, from residue 100 to 116, is not identical to that in the DMSO reductases. A direct consequence of the missing residue is a wider accessible space, adjacent to the molybdenum active center, which potentially exists to accommodates the somewhat bulkier trimethylamine-oxide molecules more easily than the dimethylsulfoxide molecules. This different demonstrates how an enzyme's form is almost always directly tied to its function.
However, recent discrepancies have risen regarding the structure of the TMAO reductase active site. The proposed active site contains several anomalous bond lengths; one Mo-O bond length is too short for a Mo-O single-bond coordination, and the four Mo-S bond lengths are all considerably longer than expected. Moreover, the proposed molybdenum coordination of the active site is extremely crowded, with the distances between several supposedly nonbonding atoms being significantly shorter than the sum of their van der Waals radii and some bond angles being unreasonably small. Now, it is being hypothesized that this overcrowding is due to the cocrystallization of multiple forms of the enzyme. | 1 | Biochemistry |
The operating environment is not simply black space, but one with solar radiation and diffuse radiation reflected and emitted from the sun (stars), earth, other objects, and or the spacecraft's own propulsion. It is possible to "orient" the droplet sheet edge towards an external heat source but the sheet area would still be subject to radiation from other sources. Most of the presented solutions of the equation of radiative transfer are practical simplifications by introducing assumptions.
In order to achieve high collection efficiency splashing of the droplet on the collector surface has to be minimized. It was determined that droplet collector with an incidence angle of 35 degrees can prevent a uniform droplet stream with droplet diameter 250 µm and a velocity of 16 m/s from splashing under microgravity condition.
Another solution is to have a liquid film formed on the inner surface of the collector. When the droplet streams are absorbed in this liquid film, no splashes should be formed. A miscapture rate of incoming droplets was required to be less than 10. The droplet diameter was determined to be less than 300 µm and the droplet speed less than 20 m/s.
If a ferrofluid is used a magnetic focusing means can effectively suppress splashing.
As the droplet sheet is in free fall a spacecraft performing a maneuver or angular acceleration would lose coolant. Even a magnetically focused LDR has a very limited tolerance of less than 10 g.
A droplet generator has approximately 10 – 10 holes (orifices) per system with diameters of 50–20 µm.
These orifices are more susceptible to damage than a conventional solid radiator or heat pipe which may affect droplet formation and droplet stream flow direction, potentially causing fluid loss. | 7 | Physical Chemistry |
In geology, the terms sinistral and dextral refer to the horizontal component of the movement of blocks on either side of a fault or the sense of movement within a shear zone. These are terms of relative direction, as the movement of the blocks is described relative to each other when viewed from above. Movement is sinistral (left-handed) if the block on the other side of the fault moves to the left, or if straddling the fault the left side moves toward the observer. Movement is dextral (right-handed) if the block on the other side of the fault moves to the right, or if straddling the fault the right side moves toward the observer. | 4 | Stereochemistry |
The term "polymer" derives . The term was coined in 1833 by Jöns Jacob Berzelius, though with a definition distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, who spent the next decade finding experimental evidence for this hypothesis. | 7 | Physical Chemistry |
Another level of complexity comes from the existence of slow redox-driven reactions that may change the activity of the enzyme and make the response depart from steady-state. Here, slow means that the time scale of the (in)activation is similar to the voltammetric time scale . If a RDE is used, these slow (in)activations are detected by a hysteresis in the catalytic voltammogram that is not due to mass-transport. The hysteresis may disappear at very fast scan rates (if the inactivation has no time to proceed) or at very slow scan rates (if the (in)activation reaction reaches a steady-state). | 7 | Physical Chemistry |
The following are examples of simple and aromatic carbocycles, inorganic cyclic compounds, and heterocycles: | 4 | Stereochemistry |
While the exact mechanism of action is still unknown many important protein physical properties play a part in the Vroman Effect. Proteins have many properties that are important to take into consideration when discussing protein adsorption. These properties include the protein size, charge, mobility, stability, and the structure and composition of the different protein domains that make up the protein's tertiary structure. Protein size determines the molecular weight. Protein charge determines whether preferentially or selective favorable interactions will exist between the protein and a biomaterial. Protein mobility plays a factor in adsorption kinetics. | 7 | Physical Chemistry |
In 1982 The Electrochemical Society created the [https://web.archive.org/web/20150721022447/http://www.electrochem.org/awards/ecs/ecs_awards.htm#k Norman Hackerman Young Author Award] to honor the best paper published in the Journal of the Electrochemical Society for a topic in the field of electrochemical science and technology by a young author or authors. In 2000 the Welch Foundation created the Norman Hackerman Award in Chemical Research to recognize the work of young researchers in Texas. The Rice Board of Trustees established the Norman Hackerman Fellowship in Chemistry in honor of Hackermans 90th birthday in 2002. In 2008, the original Experimental Science Building at the University of Texas at Austin campus was demolished and rebuilt as the Norman Hackerman Experimental Science Building in his name and honor. The building was completed in late 2010, with the opening and dedication ceremony on March 2, 2011, which was both Hackermans 99th Birthday and the 175th Anniversary of Texas Independence. The main building at the J. Erik Jonsson Center of the National Academy of Sciences is Hackerman House, named in his honor. Hackerman House overlooks Quissett Harbor in Woods Hole MA, on Cape Cod. | 7 | Physical Chemistry |
Exome sequencing can be used to diagnose the genetic cause of disease in a patient. Identification of the underlying disease gene mutation(s) can have major implications for diagnostic and therapeutic approaches, can guide prediction of disease natural history, and makes it possible to test at-risk family members. There are many factors that make exome sequencing superior to single gene analysis including the ability to identify mutations in genes that were not tested due to an atypical clinical presentation or the ability to identify clinical cases where mutations from different genes contribute to the different phenotypes in the same patient.
Having diagnosed a genetic cause of a disease, this information may guide the selection of appropriate treatment. The first time this strategy was performed successfully in the clinic was in the treatment of an infant with inflammatory bowel disease. A number of conventional diagnostics had previously been used, but the results could not explain the infants symptoms. Analysis of exome sequencing data identified a mutation in the XIAP gene. Knowledge of this genes function guided the infant's treatment, leading to a bone marrow transplantation which cured the child of disease.
Researchers have used exome sequencing to identify the underlying mutation for a patient with Bartter Syndrome and congenital chloride diarrhea. Bilgular's group also used exome sequencing and identified the underlying mutation for a patient with severe brain malformations, stating "[These findings] highlight the use of whole exome sequencing to identify disease loci in settings in which traditional methods have proved challenging... Our results demonstrate that this technology will be particularly valuable for gene discovery in those conditions in which mapping has been confounded by locus heterogeneity and uncertainty about the boundaries of diagnostic classification, pointing to a bright future for its broad application to medicine".
Researchers at University of Cape Town, South Africa used exome sequencing to discover the genetic mutation of CDH2 as the underlying cause of a genetic disorder known as arrhythmogenic right ventricle cardiomyopathy (ARVC)‚ which increases the risk of heart disease and cardiac arrest. [https://www.news.uct.ac.za/article/-2017-03-10-uct-researchers-discover-heart-attack-gene] | 1 | Biochemistry |
A study on molecular markers in human aortic endothelial cells published that aglycone stopped cell migration but not monocyte adhesion, which is the initial step of atherosclerotic plaque formation. Another study exploring the benefits of extra virgin olive oil consumption in preventing age-related neurodegenerative diseases found aglycone greatly increased the cognitive performance of mice. The aglycone-fed mice displayed strong autophagic reactions, mTOR regulation, and reduced plaque deposits and ß-amyloid levels. | 0 | Organic Chemistry |
Both prokaryotic and eukarotic genomes are organized into large loops of protein-bound DNA. In eukaryotes, the bases of the loops are called scaffold attachment regions (SARs) and they consist of stretches of DNA that bind an RNA/protein complex to stabilize the loop. There are about 100,000 loops in the human genome and each one consists of about 100 bp of DNA. The total amount of DNA devoted to SARs accounts for about 0.3% of the human genome. | 1 | Biochemistry |
It has been shown previously that OMgp (oligodendrocyte myelin glycoprotein) clusters at nodes of Ranvier and may regulate paranodal architecture, node length and axonal sprouting at nodes. However, a follow-up study showed that the antibody used previously to identify OMgp at nodes crossreacts with another node-enriched component versican V2 and that OMgp is not required for the integrity of nodes and paranodes, arguing against the previously reported localization and proposed functions of OMgp at nodes. | 1 | Biochemistry |
An ionic liquid (IL) is a salt in the liquid state at ambient conditions. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as . While ordinary liquids such as water and gasoline are predominantly made of electrically neutral molecules, ionic liquids are largely made of ions. These substances are variously called liquid electrolytes, ionic melts, ionic fluids, fused salts, liquid salts, or ionic glasses.
Ionic liquids have many potential applications. They are powerful solvents and can be used as electrolytes. Salts that are liquid at near-ambient temperature are important for electric battery applications, and have been considered as sealants due to their very low vapor pressure.
Any salt that melts without decomposing or vaporizing usually yields an ionic liquid. Sodium chloride (NaCl), for example, melts at into a liquid that consists largely of sodium cations () and chloride anions (). Conversely, when an ionic liquid is cooled, it often forms an ionic solid—which may be either crystalline or glassy.
The ionic bond is usually stronger than the Van der Waals forces between the molecules of ordinary liquids. Because of these strong interactions, salts tend to have high lattice energies, manifested in high melting points. Some salts, especially those with organic cations, have low lattice energies and thus are liquid at or below room temperature. Examples include compounds based on the 1-ethyl-3-methylimidazolium (EMIM) cation and include: EMIM:Cl, EMIMAc (acetate anion), EMIM dicyanamide, ()()·, that melts at ; and 1-butyl-3,5-dimethylpyridinium bromide which becomes a glass below .
Low-temperature ionic liquids can be compared to ionic solutions, liquids that contain both ions and neutral molecules, and in particular to the so-called deep eutectic solvents, mixtures of ionic and non-ionic solid substances which have much lower melting points than the pure compounds. Certain mixtures of nitrate salts can have melting points below 100 °C. | 7 | Physical Chemistry |
Stefan adhesion is the normal stress (force per unit area) acting between two discs when their separation is attempted. Stefan's law governs the flow of a viscous fluid between the solid parallel plates and thus the forces acting when the plates are approximated or separated.
The force resulting at distance between two parallel circular disks of radius , immersed in a Newtonian fluid with viscosity , at time , depends on the rate of change of separation :
Stefan adhesion is mentioned in conjunction with bioadhesion by mucus-secreting animals. Nevertheless, most such systems violate the assumptions of the equation. In addition, these systems are much more complex when the fluid is non-Newtonian or inertial effects are relevant (high flow rate). | 6 | Supramolecular Chemistry |
Ferromanganese is an alloy of iron and manganese, with other elements such as silicon, carbon, sulfur, nitrogen and phosphorus. The primary use of ferromanganese is as a type of processed manganese source to add to different types of steel, such as stainless steel. Global production of low-carbon ferromanganese (i.e. alloys with less than 2% carbon content) reached 1.5 megatons in 2010. | 8 | Metallurgy |
The zirconium-catalyzed asymmetric carbo-alumination reaction (or ZACA reaction) was developed by Nobel laureate Ei-ichi Negishi. It facilitates the chiral functionalization of alkenes using organoaluminium compounds under the influence of chiral bis-indenylzirconium catalysts (e.g. bearing chiral terpene residues, as in (+)- or (−)-bis[(1-neomenthyl)indenyl]zirconium dichloride). In a first step the alkene inserts into an Al-C bond of the reagent, forming a new chiral organoaluminium compound in which the aluminium atom occupies the lesser hindered position. This intermediate is usually oxidized by oxygen to form the corresponding chiral alcohol (cf. hydroboration–oxidation reaction). The reaction can also be applied to dienes, where the least sterically hindered double bond is attacked selectively. | 0 | Organic Chemistry |
RDRP – sometimes misleadingly called free radical polymerization – is one of the most widely used polymerization processes since it can be applied
*to a great variety of monomers
*it can be carried out in the presence of certain functional groups
*the technique is rather simple and easy to control
*the reaction conditions can vary from bulk over solution, emulsion, miniemulsion to suspension
*it is relatively inexpensive compared with competitive techniques
The steady-state concentration of the growing polymer chains is 10 M by order of magnitude, and the average life time of an individual polymer radical before termination is about 5–10 s. A drawback of the conventional radical polymerization is the limited control of chain architecture, molecular weight distribution, and composition. In the late 20th century it was observed that when certain components were added to systems polymerizing by a chain mechanism they are able to react reversibly with the (radical) chain carriers, putting them temporarily into a dormant state.
This had the effect of prolonging the lifetime of the growing polymer chains (see above) to values comparable with the duration of the experiment. At any instant most of the radicals are in the inactive (dormant) state, however, they are not irreversibly terminated (‘dead’). Only a small fraction of them are active (growing), yet with a fast rate of interconversion of active and dormant forms, faster than the growth rate, the same probability of growth is ensured for all chains, i.e., on average, all chains are growing at the same rate. Consequently, rather than a most probable distribution, the molecular masses (degrees of polymerization) assume a much narrower Poisson distribution, and a lower dispersity prevails.
IUPAC also recognizes the alternative name, ‘controlled reversible-deactivation radical polymerization’ as acceptable, "provided the controlled context is specified, which in this instance comprises molecular mass and molecular mass distribution." These types of radical polymerizations are not necessarily ‘living’ polymerizations, since chain termination reactions are not precluded".
The adjective ‘controlled’ indicates that a certain kinetic feature of a polymerization or structural aspect of the polymer molecules formed is controlled (or both). The expression ‘controlled polymerization’ is sometimes used to describe a radical or ionic polymerization in which reversible-deactivation of the chain carriers is an essential component of the mechanism and interrupts the propagation that secures control of one or more kinetic features of the polymerization or one or more structural aspects of the macromolecules formed, or both. The expression ‘controlled radical polymerization’ is sometimes used to describe a radical polymerization that is conducted in the presence of agents that lead to e.g. atom-transfer radical polymerization (ATRP), nitroxide-(aminoxyl) mediated polymerization (NMP), or reversible-addition-fragmentation chain transfer (RAFT) polymerization. All these and further controlled polymerizations are included in the class of reversible-deactivation radical polymerizations. Whenever the adjective ‘controlled’ is used in this context the particular kinetic or the structural features that are controlled have to be specified. | 7 | Physical Chemistry |
Ordinarily the nitrogen atom in the amine group is reacting as a nucleophile by way of its lone pair. This polarity can be reversed when a primary or secondary amine is substituted with a good leaving group (such as a halogen atom or an alkoxy group). The resulting N-substituted compound can behave as an electrophile at the nitrogen atom and react with a nucleophile as for example in the electrophilic amination of carbanions. | 0 | Organic Chemistry |
Chromosomal landing is a genetic technique used to identify and isolate clones in a genetic library. Chromosomal landing reduces the problem of analyzing large, and/or highly repetitive genomes by minimizing the need for chromosome walking. It is based on the principle that the expected average between-marker distances can be smaller than the average insert length of a clone library containing the gene of interest.
From the abstract of :
:The strategy of chromosome walking is based on the assumption that it is difficult and time consuming to find DNA markers that are physically close to a gene of interest. Recent technological developments invalidate this assumption for many species. As a result, the mapping paradigm has now changed such that one first isolates one or more DNA marker(s) at a physical distance from the targeted gene that is less than the average insert size of the genomic library being used for clone isolation. The DNA marker is then used to screen the library and isolate (or land on) the clone containing the gene, without any need for chromosome walking and its associated problems. Chromosome landing, together with the technology that has made it possible, is likely to become the main strategy by which map-based cloning is applied to isolate both major genes and genes underlying quantitative traits in plant species. | 1 | Biochemistry |
In volatilization methods, removal of the analyte involves separation by heating or chemically decomposing a volatile sample at a suitable temperature. In other words, thermal or chemical energy is used to precipitate a volatile species. For example, the water content of a compound can be determined by vaporizing the water using thermal energy (heat). Heat can also be used, if oxygen is present, for combustion to isolate the suspect species and obtain the desired results.
The two most common gravimetric methods using volatilization are those for water and carbon dioxide. An example of this method is the isolation of sodium hydrogen bicarbonate (the main ingredient in most antacid tablets) from a mixture of carbonate and bicarbonate. The total amount of this analyte, in whatever form, is obtained by addition of an excess of dilute sulfuric acid to the analyte in solution.
In this reaction, nitrogen gas is introduced through a tube into the flask which contains the solution. As it passes through, it gently bubbles. The gas then exits, first passing a drying agent (here CaSO, the common desiccant Drierite). It then passes a mixture of the drying agent and sodium hydroxide which lies on asbestos or Ascarite II, a non-fibrous silicate containing sodium hydroxide. The mass of the carbon dioxide is obtained by measuring the increase in mass of this absorbent. This is performed by measuring the difference in weight of the tube in which the ascarite contained before and after the procedure.
The calcium sulfate (CaSO) in the tube retains carbon dioxide selectively as it's heated, and thereby, removed from the solution. The drying agent absorbs any aerosolized water and/or water vapor (reaction 3.). The mix of the drying agent and NaOH absorbs the CO and any water that may have been produced as a result of the absorption of the NaOH (reaction 4.).
The reactions are:
Reaction 3 - absorption of water
NaHCO + HSO → CO) + HO + NaHSO
Reaction 4. Absorption of CO and residual water
CO + 2 NaOH NaCO + HO | 3 | Analytical Chemistry |
A circular filter paper is taken and the sample is deposited at the center of the paper. After drying the spot, the filter paper is tied horizontally on a Petri dish containing solvent, so that the wick of the paper is dipped in the solvent. The solvent rises through the wick and the components are separated into concentric rings. | 3 | Analytical Chemistry |
In positive plant-insect interactions, GLVs are used as a form of defense. They attract predators to plants that are being preyed upon by herbivores.
For example, female parasitoid wasps from two different families, Microplitis croceipes and Netelia heroica, can be attracted to plants that are emitting GLVs due to wounding from caterpillars. Maize plants emit volatiles to attract the parasitic wasps Cotesia marginiventris and Microplitis rufiventris to attack African cotton leafworm. In some species GLVs enhance the attraction of sex pheromones. For example, green leaf volatiles have been found to increase the response of tobacco budworm to sex pheromone. Budworm larvae feed on tobacco, cotton, and various flowers and weeds, and in turn can be fed on by the larvae of cohabiting species that are attracted by GLVs.
In another study, a multi-plant relationship was reported. The parasitic wasps (Vespula germanica and V. vulgaris) prey on caterpillar (Pieris brassicae)-infested cabbage leaves that emit GLVs. The same GLVs are emitted by the orchids (Epipactis purpurata and E. helleborine) through pheromone release. The orchids benefit from attracting the wasps, not to protect them from insects, but because the wasps aid in pollination.
Benefits of GLV release have also been reported in soybeans grown in Iowa. When these soybean plants became heavily infested by aphids, the amount of GLV released far surpassed normal levels and as a result, more spotted lady beetles were attracted to the pheromone releasing plants and preyed on the bugs eating the plant. The stimulus of aphid predation is chemically transmitted through the plant to coordinate an increase release of GLV’s. The particular chemical released is unique to these spotted lady beetles and when different species of beetles were tested, there wasn’t any extra inclination for them to move towards GLV releasing plants. This indicates that these soybeans evolved ability to release species-specific pheromones to aid in their survival. | 1 | Biochemistry |
The bulk distribution coefficient is used to calculate the elemental composition for any element that makes up a mineral in a rock. The bulk distribution coefficient, , is defined as
where is the element of interest in the mineral, and is the weight fraction of mineral in the rock. is the distribution coefficient for the element in mineral . This constant can be used to describe how individual elements in a mineral is concentrated in two different phases. During chemical fractionation, certain elements may become more or less concentrated, which can allow geochemists to quantify the different stages of magma differentiation. Ultimately, these measurements can be used to provide further understanding of elemental behavior in different geologic settings. | 9 | Geochemistry |
The first nearly complete human genomes sequenced were two Americans of predominantly Northwestern European ancestry in 2007 (J. Craig Venter at 7.5-fold coverage, and James Watson at 7.4-fold). This was followed in 2008 by sequencing of an anonymous Han Chinese man (at 36-fold), a Yoruban man from Nigeria (at 30-fold), a female clinical geneticist (Marjolein Kriek) from the Netherlands (at 7 to 8-fold), and a female leukemia patient in her mid-50s (at 33 and 14-fold coverage for tumor and normal tissues). Steve Jobs was among the first 20 people to have their whole genome sequenced, reportedly for the cost of $100,000. , there were 69 nearly complete human genomes publicly available. In November 2013, a Spanish family made their personal genomics data publicly available under a Creative Commons public domain license. The work was led by Manuel Corpas and the data obtained by direct-to-consumer genetic testing with 23andMe and the Beijing Genomics Institute. This is believed to be the first such Public Genomics dataset for a whole family. | 1 | Biochemistry |
Albert Fredrick Ottomar Germann (February 18, 1886 – December 22, 1976) was an American physical chemist, university professor, and chemical entrepreneur. | 7 | Physical Chemistry |
In the 2000s the application of the bulk material analyzer was extended to include minerals. Today, analyzers are found in copper, iron ore, and phosphates, to name a few. One of the advantages of these analyzers is the timeliness of information for the user. Another is the avoidance of physical sampling. | 3 | Analytical Chemistry |
Dynabeads are superparamagnetic spherical polymer particles with a uniform size and a consistent, defined surface for the adsorption or coupling of various bioreactive molecules or cells. | 7 | Physical Chemistry |
Leonidas Zervas (, ; 21 May 1902 – 10 July 1980) was a Greek organic chemist who made seminal contributions in peptide chemical synthesis. Together with his mentor Max Bergmann they laid the foundations for the field in 1932 with their major discovery, the Bergmann-Zervas carboxybenzoxy oligopeptide synthesis which remained unsurpassed in utility for the next two decades. The carboxybenzyl protecting group he discovered is often abbreviated Z in his honour.
Throughout his life Zervas also served in many important posts, including President of the Academy of Athens or briefly Minister of Industry of Greece. He received numerous awards and honours during his life and posthumously, such as Foreign Member of the USSR Academy of Sciences or the first Max Bergmann golden medal. | 0 | Organic Chemistry |
HNF4 was originally classified as an orphan receptor that exhibits constitutive transactivation activity apparently by being continuously bound to a variety of fatty acids. The existence of a ligand for HNF4 has been somewhat controversial, but linoleic acid (LA) has been identified as the endogenous ligand of native HNF4 expressed in mouse liver; the binding of LA to HNF4 is reversible.
The ligand binding domain of HNF4, as with other nuclear receptors, adopts a canonical alpha helical sandwich fold and interacts with co-activator proteins.
HNF4 binds to the consensus sequence AGGTCAaAGGTCA in order to activate transcription. | 1 | Biochemistry |
The concept of prochirality is necessary for understanding some aspects of enzyme stereospecificity. Ogston pointed out that when a symmetrical molecule is placed in an asymmetric environment, such as the surface of an enzyme, supposedly identically placed groups become distinguishable. In this way he showed that earlier exclusion of non-chiral citrate as a possible intermediate in the tricarboxylate cycle was mistaken.
A coffee mug with one handle is an everyday example of a prochiral object. If it is placed in an achiral corrosive liquid, such as a concentrated acid, then the left and right-hand sides will be corroded equally because there is nothing to distinguish them. However, if the mug is held in a person's right hand it is easy to drink out of the left-hand side but difficult to drink out of the right-hand side. In other words, an achiral environment such as an acid cannot distinguish between the two sides of a prochiral, but a chiral object like a person can. Thus a chiral enzyme such as aconitase can act differently on two apparently equivalent groups on a prochiral molecule, so citrate can be an intermediate in the tricarboxylate cycle. | 4 | Stereochemistry |
This method was first developed by Benesi and Hildebrand in 1949, as a means to explain a phenomenon where iodine changes color in various aromatic solvents. This was attributed to the formation of an iodine-solvent complex through acid-base interactions, leading to the observed shifts in the absorption spectrum. Following this development, the Benesi–Hildebrand method has become one of the most common strategies for determining association constants based on absorbance spectra. | 7 | Physical Chemistry |
One of the largest hurdles for genome-wide CRISPR screening is ensuring adequate coverage of the sgRNA library across the cell population. Evidence so far has suggested that each sgRNA should be represented and maintained in a minimum of 200-300 cells.
Considering that the standard protocol uses a multiplicity of infection of ~0.3, and a transduction efficiency of 30-40% the number of cells required to produce and maintain suitable coverage becomes very large. By way of example, the most popular human sgRNA library is the [https://www.addgene.org/pooled-library/zhang-human-gecko-v2/?gclid=Cj0KCQiA1-3yBRCmARIsAN7B4H2cTsJq44UZen4GOpdr-IbSGuTdqS_BjcCdi9x0PtthkDXvoIztPDgaAoNIEALw_wcB/ GeCKO v2 library] created by the Zhang lab; it contains 123,411 sgRNAs. Studies using this library commonly transduce more than 1x10 cells
As CRISPR continues to exhibit low noise and minimal off-target effects, an alternative strategy is to reduce the number of sgRNAs per gene for a primary screen. Less stringent cut-offs are used for hit selection, and additional sgRNAs are later used in a more specific secondary screen. This approach is demonstrated by Doench et al. (2016), who found that >92% of genes recovered using the standard protocol were also recovered using fewer sgRNAs per gene. They suggest that this strategy could be useful in studies where scale-up is prohibitively costly. | 1 | Biochemistry |
Bioluminescence is the process of light emission in living organisms. Bioluminescence imaging utilizes native light emission from one of several organisms which bioluminesce, also known as luciferase enzymes. The three main sources are the North American firefly, the sea pansy (and related marine organisms), and bacteria like Photorhabdus luminescens and Vibrio fischeri. The DNA encoding the luminescent protein is incorporated into the laboratory animal either via a viral vector or by creating a transgenic animal. Rodent models of cancer spread can be studied through bioluminescence imaging.for e.g.Mouse models of breast cancer metastasis.
Systems derived from the three groups above differ in key ways:
* Firefly luciferase requires D-luciferin to be injected into the subject prior to imaging. The peak emission wavelength is about 560 nm. Due to the attenuation of blue-green light in tissues, the red-shift (compared to the other systems) of this emission makes detection of firefly luciferase much more sensitive in vivo.
* Renilla luciferase (from the Sea pansy) requires its substrate, coelenterazine, to be injected as well. As opposed to luciferin, coelenterazine has a lower bioavailability (likely due to MDR1 transporting it out of mammalian cells). Additionally, the peak emission wavelength is about 480 nm.
* Bacterial luciferase has an advantage in that the lux operon used to express it also encodes the enzymes required for substrate biosynthesis. Although originally believed to be functional only in prokaryotic organisms, where it is widely used for developing bioluminescent pathogens, it has been genetically engineered to work in mammalian expression systems as well. This luciferase reaction has a peak wavelength of about 490 nm.
While the total amount of light emitted from bioluminescence is typically small and not detected by the human eye, an ultra-sensitive CCD camera can image bioluminescence from an external vantage point. | 1 | Biochemistry |
A ternary rhodium-centered bipyramidal dibismuth complex is an example of subhalide complexes with interesting geometry and unusual electronic properties, particularly what has been reported as an example of Möbius aromaticity. The complex exhibits a 4-electron-5-centered bond in the central plane occupied by a Bi equatorial pentagon with the rhodium center in the middle. Based on the electronic analysis carried out by Ruck (2003), the bismuth bonding consists of 2-centered-2-electron bonds, namely, Bi-Rh and Bi-Br one (see structure on the right).
The electronic analysis was carried out starting with counting the available skeletal electrons. Each of the 7 bismuth atoms contribute a total of 3x7=21 electrons (3 per each atom), while Rh gives all of its 9 electrons and the 8 bridging bromide atoms yield 3 electrons each. The total skeletal electron count is thus 54. The total skeletal electron count gets distributed as follows: 2 electrons per each of the 16 2c-2e Bi-Br bond, 2 electrons per each of the 7 2c-2e Rh-Bi metallic bond, 2 rhodium lone pairs remaining on the Rh centre (total of 4e), and 4 electrons for 5c-4e bond pertaining to the central pentagon. The sum of electrons used in bonding is therefore 54. Hence, the subhalide complex is electron-precise, i.e., with all of its skeletal electrons involved in chemical bonding.
The bonding in such a system was compared to the aromatic cyclopentadienyl aromatic anion. Contrary to the π-type all in-phase orbital overlap exhibited by the organic cyclopentadienyl anion, σ-type bonding of the RhBi unit yields a phase change for an orbital pair (see figure).
The relative orbital energy diagram is rationalized for each of the systems relying on the Frost-Musulin mnemonic. The two lone pairs stemming from the rhodium metallic center are localized on the lowest-lying twicely degenerate set of molecular orbitals, consistent with the Möbius-type aromaticity. For reference, the electronics of the aromatic organice cyclopentadienyl unit is shown to the right of the rhodium-centered pentagonal Bi unit. As can be seen, Hückel rules dictate the molecular orbital splitting is inverted compared to its metallic counterpart, the highest-occupied molecular orbitals this time being twicely degenerate. | 7 | Physical Chemistry |
As a byproduct of the ethoxylation process, a route to some ingredients found in cleansing and moisturizing products, dioxane can contaminate cosmetics and personal care products such as deodorants, perfumes, shampoos, toothpastes and mouthwashes. The ethoxylation process makes the cleansing agents, such as sodium laureth sulfate and ammonium laureth sulfate, less abrasive and offers enhanced foaming characteristics. 1,4-Dioxane is found in small amounts in some cosmetics, a yet unregulated substance used in cosmetics in both China and the U.S. Research has found the chemical in ethoxylated raw ingredients and in off-the-shelf cosmetic products. The Environmental Working Group (EWG) found that 97% of hair relaxers, 57% of baby soaps and 22 percent of all products in Skin Deep, their database for cosmetic products, are contaminated with 1,4-dioxane.
Since 1979 the U.S. Food and Drug Administration (FDA) have conducted tests on cosmetic raw materials and finished products for the levels of 1,4-dioxane. 1,4-Dioxane was present in ethoxylated raw ingredients at levels up to 1410 ppm (~0.14%wt), and at levels up to 279 ppm (~0.03%wt) in off the shelf cosmetic products. Levels of 1,4-dioxane exceeding 85 ppm (~0.01%wt) in children's shampoos indicate that close monitoring of raw materials and finished products is warranted. While the FDA encourages manufacturers to remove 1,4-dioxane, it is not required by federal law.
On 9 December 2019, New York passed a bill to ban the sale of cosmetics with more than 10 ppm of 1,4-dioxane as of the end of 2022. The law will also prevent the sale of household cleaning and personal care products containing more than 2 ppm of 1,4-dioxane at the end of 2022. | 6 | Supramolecular Chemistry |
Capillary tubes are attached to both the solvent and the solution compartments. In this case the osmotic pressure is provided by the additional pressure of the fluid in the solution compartment. The difference in the height of the fluid in the capillary tube of solution compartment versus the height of the fluid in the capillary tube of the solvent compartment is measured once the solution reaches equilibrium to calculate the osmotic pressure.
, osmotic pressure
, change in height
, density
, acceleration due to gravity
The main disadvantage of static osmometry is the long time it takes for equilibrium to be reached. It often takes 3 or more hours after the solute is added for the static osmometer to reach equilibrium. | 7 | Physical Chemistry |
In a cell, there are several non-canonical bases present: CpG islands in DNA (often methylated), all eukaryotic mRNA (capped with a methyl-7-guanosine), and several bases of rRNAs (methylated). Often, tRNAs are heavily modified postranscriptionally in order to improve their conformation or base pairing, in particular in or near the anticodon: inosine can base pair with C, U, and even with A, whereas thiouridine (with A) is more specific than uracil (with a purine). Other common tRNA base modifications are pseudouridine (which gives its name to the TΨC loop), dihydrouridine (which does not stack as it is not aromatic), queuosine, wyosine, and so forth. Nevertheless, these are all modifications to normal bases and are not placed by a polymerase. | 1 | Biochemistry |
The ideal gas law, also called the general gas equation, is the equation of state of a hypothetical ideal gas. It is a good approximation of the behavior of many gases under many conditions, although it has several limitations. It was first stated by Benoît Paul Émile Clapeyron in 1834 as a combination of the empirical Boyles law, Charless law, Avogadros law, and Gay-Lussacs law. The ideal gas law is often written in an empirical form:
where , and are the pressure, volume and temperature respectively; is the amount of substance; and is the ideal gas constant.
It can also be derived from the microscopic kinetic theory, as was achieved (apparently independently) by August Krönig in 1856 and Rudolf Clausius in 1857. | 7 | Physical Chemistry |
Examples of photochemical organic reactions are electrocyclic reactions, radical reactions, photoisomerization, and Norrish reactions.
Alkenes undergo many important reactions that proceed via a photon-induced π to π* transition. The first electronic excited state of an alkene lacks the π-bond, so that rotation about the C–C bond is rapid and the molecule engages in reactions not observed thermally. These reactions include cis-trans isomerization and cycloaddition to other (ground state) alkene to give cyclobutane derivatives. The cis-trans isomerization of a (poly)alkene is involved in retinal, a component of the machinery of vision. The dimerization of alkenes is relevant to the photodamage of DNA, where thymine dimers are observed upon illuminating DNA with UV radiation. Such dimers interfere with transcription. The beneficial effects of sunlight are associated with the photochemically-induced retro-cyclization (decyclization) reaction of ergosterol to give vitamin D. In the DeMayo reaction, an alkene reacts with a 1,3-diketone reacts via its enol to yield a 1,5-diketone. Still another common photochemical reaction is Howard Zimmerman's di-π-methane rearrangement.
In an industrial application, about 100,000 tonnes of benzyl chloride are prepared annually by the gas-phase photochemical reaction of toluene with chlorine. The light is absorbed by chlorine molecules, the low energy of this transition being indicated by the yellowish color of the gas. The photon induces homolysis of the Cl-Cl bond, and the resulting chlorine radical converts toluene to the benzyl radical:
:Cl + hν → 2 Cl·
:CHCH + Cl· → CHCH· + HCl
:CHCH· + Cl· → CHCHCl
Mercaptans can be produced by photochemical addition of hydrogen sulfide (HS) to alpha olefins. | 5 | Photochemistry |
The frequency of introns within different genomes is observed to vary widely across the spectrum of biological organisms. For example, introns are extremely common within the nuclear genome of jawed vertebrates (e.g. humans, mice, and pufferfish (fugu)), where protein-coding genes almost always contain multiple introns, while introns are rare within the nuclear genes of some eukaryotic microorganisms, for example bakers/brewers yeast (Saccharomyces cerevisiae). In contrast, the mitochondrial genomes of vertebrates are entirely devoid of introns, while those of eukaryotic microorganisms may contain many introns.
A particularly extreme case is the Drosophila dhc7 gene containing a ≥3.6 megabase (Mb) intron, which takes roughly three days to transcribe. On the other extreme, a 2015 study suggests that the shortest known metazoan intron length is 30 base pairs (bp) belonging to the human MST1L gene. The shortest known introns belong to the heterotrich ciliates, such as Stentor coeruleus, in which most (> 95%) introns are 15 or 16 bp long. | 1 | Biochemistry |
Symptoms of overdosing are similar to adverse effects of standard doses: severe hyponatraemia, somnolence, uncoordinated/unsteady gait, hemiparesis (weakness of one side of the body), along with visual and gastrointestinal disturbances. No specific antidote is available. Eslicarbazepine and metabolites can be dialyzed. | 4 | Stereochemistry |
Cyp33 in mammals causes isomerization in MLL1. MLL1 is a multiprotein complex that regulates gene expression and chromosomal translocations involving this gene often lead to leukemia. MLL's target genes include HOXC8, HOXA9, CDKN1B, and C-MYC. MLL also has two binding domains: a Cyp33 RNA-recognition motif domain (RRM), and a PHD3 domain that binds to H3K4me3 or Cyp33 RRM. Cyp33 has the ability to downregulate the expression of these genes through proline isomerization at the peptide bond between His1628 and Pro1629 within MLL. This bond lies in a sequence between the PHD3 finger of MLL1 and the bromeodomain of MLL1, and its isomerization mediates the bonding of the PHD3 domain and the Cyp33 RRM domain. When these two domains are bonded transcription is repressed through recruitment of histone deacetylases to MLL1 and inhibition of H3K4me3. | 4 | Stereochemistry |
Single-molecule real-time sequencing (SMRT) is used in the epigenomic and epitranscriptomic fields. As regards epigenomics, thousands of zero-mode waveguides (ZMWs) are used to capture the DNA polymerase: when a modified base is present, the biophysical dynamics of its movement changes, creating a unique kinetic signature before, during, and after the base incorporation.
SMRT sequencing can be used to detect modified bases in RNA, including m6A sites. In this case, a reverse transcriptase is used as enzyme with ZMWs to observe the cDNA synthesis in real time. The incorporation of synthetically designed m6A sites leaves a kinetic signature and increases the interpulse duration (IPD).
There are some issues concerning the reading of homonucleotide stretches and the base resolution of m6A therein, due to the stuttering of reverse transcriptase. Secondly, the throughput is too low for transcriptome-wide approaches.
One of the most commonly used platform is the SMRT sequencing technology by Pacific Biosciences. | 1 | Biochemistry |
Probably the most widely used current applications of refrigeration are for air conditioning of private homes and public buildings, and refrigerating foodstuffs in homes, restaurants and large storage warehouses. The use of refrigerators and walk-in coolers and freezers in kitchens, factories and warehouses for storing and processing fruits and vegetables has allowed adding fresh salads to the modern diet year round, and storing fish and meats safely for long periods.
The optimum temperature range for perishable food storage is .
In commerce and manufacturing, there are many uses for refrigeration. Refrigeration is used to liquefy gases – oxygen, nitrogen, propane, and methane, for example. In compressed air purification, it is used to condense water vapor from compressed air to reduce its moisture content. In oil refineries, chemical plants, and petrochemical plants, refrigeration is used to maintain certain processes at their needed low temperatures (for example, in alkylation of butenes and butane to produce a high-octane gasoline component). Metal workers use refrigeration to temper steel and cutlery. When transporting temperature-sensitive foodstuffs and other materials by trucks, trains, airplanes and seagoing vessels, refrigeration is a necessity.
Dairy products are constantly in need of refrigeration, and it was only discovered in the past few decades that eggs needed to be refrigerated during shipment rather than waiting to be refrigerated after arrival at the grocery store. Meats, poultry and fish all must be kept in climate-controlled environments before being sold. Refrigeration also helps keep fruits and vegetables edible longer.
One of the most influential uses of refrigeration was in the development of the sushi/sashimi industry in Japan. Before the discovery of refrigeration, many sushi connoisseurs were at risk of contracting diseases. The dangers of unrefrigerated sashimi were not brought to light for decades due to the lack of research and healthcare distribution across rural Japan. Around mid-century, the Zojirushi corporation, based in Kyoto, made breakthroughs in refrigerator designs, making refrigerators cheaper and more accessible for restaurant proprietors and the general public. | 7 | Physical Chemistry |
The scientific goals of RSN are significant. A vast array of natural phenomena that occur throughout the world's oceans and seafloor are found in the Northeast Pacific Ocean. As a whole, the mission of RSN is to provide a human telepresence in the ocean that will serve researchers, students, educators, policymakers, and the public. Scientists will be able to conduct local investigations of such global processes as major ocean currents, active earthquake zones, creation of new seafloor, and rich environments of marine plants and animals.
RSN is also designed to help anticipate both short and long-term ocean-generated threats and opportunities. Notably, RSN will be able to monitor the tectonic activity along the plate boundary. There is hope that seismic sensors could be installed at key areas along the spreading center which would serve as an early warning system for earthquakes and tsunamis.
The existence of a long-term cabled observatory will allow for long-term measurements of biological communities. In particular, the Juan de Fuca plate's divergent plate boundary has resulted in the existence of seafloor hydrothermal vents ecosystems, and other similar groups. These deep sea communities, thriving in extremely harsh environments, pose a number of unsolved scientific questions which RSN will be capable of investigating. | 9 | Geochemistry |
In case of new constructions and for some existing structures the load level for treated welds can be increased. Using constructions for the same lifetime as before welds can transfer 1.6 times loads. This has e.g. for cranes the very positive effect of larger lifting capacity. The efficiency of cranes increases with each stroke. | 8 | Metallurgy |
*Represents the majority 85-90% of typical tall oil.
*abietic acid
**abieta-7,13-dien-18-oic acid
**13-isopropylpodocarpa -7,13-dien-15-oic acid
*Neoabietic acid
*Dehydroabietic acid
*Palustric acid
*Levopimaric acid
*Simplified formula CHO, or CHCOOH
*molecular weight 302 | 1 | Biochemistry |
In 1967 he discovered satellite DNA in plants. Through his research from 1972 to 1975, it was found that closely related species of one genus differ in satellite DNA content. In 1986 he published the monograph Satellite DNA in Springer Edition. In 2013 this monograph was edited as an eBOOK.
In 2011-17 he established a complete nucleotide sequence of four Georgian grape varieties, nuclear, chloroplast and mitochondria.
In 2015-21 he established a complete chloroplast DNA sequence of Georgian wheat species
In 1967, he defended his Candidate's Dissertation. In 1980, he defended his doctoral dissertation in the Bakh Institute of Biochemistry, Moscow. He is elected a corresponding member of the Academy of Sciences of Georgia in 1987 and a full member in 1993.
Beridze held various positions in Soviet and Georgian institutions since 1960s. | 1 | Biochemistry |
There is no single theory covering adhesion, and particular mechanisms are specific to particular material scenarios.
Five mechanisms of adhesion have been proposed to explain why one material sticks to another: | 6 | Supramolecular Chemistry |
TPVs have been proposed for use in recreational vehicles. Their ability to use multiple fuel sources makes them interesting as more sustainable fuels emerge. TPVs silent operation allows them to replace noisy conventional generators (i.e. during "quiet hours" in national park campgrounds). However, the emitter temperatures required for practical efficiencies make TPVs on this scale unlikely. | 7 | Physical Chemistry |
In electrochemistry, faradaic impedance is the resistance and capacitance acting jointly at the surface of an electrode of an electrochemical cell. The cell may be operating as either a galvanic cell generating an electric current or inversely as an electrolytic cell using an electric current to drive a chemical reaction. In the simplest nontrivial case faradaic impedance is modeled as a single resistor and single capacitor connected in parallel, as opposed say to in series or as a transmission line with multiple resistors and capacitors. | 7 | Physical Chemistry |
Tissue engineering is a relatively new field that utilizes a scaffolding as a platform upon which the desired cells proliferate. It is not clear what defines an ideal scaffold for a specific tissue type. The considerations are complex and protein adsorption only adds to the complexity. Although architecture, structural mechanics, and surface properties play a key role, understanding degradation and rate of protein adsorption are also key. In addition to the essentials of mechanics and geometry, a suitable scaffold construct will possess surface properties that are optimized for the attachment and migration of the cell types of particular interest.
Generally, it has been found that scaffolds that closely resemble the natural environments of the tissue being engineered are the most successful. As a result, much research has gone into investigating natural polymers that can be tailored, through processing methodology, toward specific design criteria. Chitosan is currently one of the most widely used polymers as it is very similar to naturally occurring glycosaminoglycan (GAGs) and it is degradable by human enzymes. | 1 | Biochemistry |
The art of cutting a gem is an exacting procedure performed on a faceting machine. The ideal product of facet cutting is a gemstone that displays a pleasing balance of internal reflections of light known as brilliance, strong and colorful dispersion which is commonly referred to as "fire", and brightly colored flashes of reflected light known as scintillation. Typically transparent to translucent stones are faceted, although opaque materials may occasionally be faceted as the luster of the gem will produce appealing reflections. Pleonaste (black spinel) and black diamond are examples of opaque faceted gemstones. | 3 | Analytical Chemistry |
The reaction occurring between double bonds and ozone is known as ozonolysis when one molecule of the gas reacts with the double bond:
The immediate result is formation of an ozonide, which then decomposes rapidly so that the double bond is cleaved. This is the critical step in chain breakage when polymers are attacked. The strength of polymers depends on the chain molecular weight or degree of polymerization, the higher the chain length, the greater the mechanical strength (such as tensile strength). By cleaving the chain, the molecular weight drops rapidly and there comes a point when it has little strength whatsoever, and a crack forms. Further attack occurs in the freshly exposed crack surfaces and the crack grows steadily until it completes a circuit and the product separates or fails. In the case of a seal or a tube, failure occurs when the wall of the device is penetrated.
The carbonyl end groups which are formed are usually aldehydes or ketones, which can oxidise further to carboxylic acids. The net result is a high concentration of elemental oxygen on the crack surfaces, which can be detected using energy-dispersive X-ray spectroscopy in the environmental SEM, or ESEM. The spectrum at left shows the high oxygen peak compared with a constant sulfur peak. The spectrum at right shows the unaffected elastomer surface spectrum, with a relatively low oxygen peak compared with the sulfur peak. | 7 | Physical Chemistry |
When observing a gas, it is typical to specify a frame of reference or length scale. A larger length scale corresponds to a macroscopic or global point of view of the gas. This region (referred to as a volume) must be sufficient in size to contain a large sampling of gas particles. The resulting statistical analysis of this sample size produces the "average" behavior (i.e. velocity, temperature or pressure) of all the gas particles within the region. In contrast, a smaller length scale corresponds to a microscopic or particle point of view.
Macroscopically, the gas characteristics measured are either in terms of the gas particles themselves (velocity, pressure, or temperature) or their surroundings (volume). For example, Robert Boyle studied pneumatic chemistry for a small portion of his career. One of his experiments related the macroscopic properties of pressure and volume of a gas. His experiment used a J-tube manometer which looks like a test tube in the shape of the letter J. Boyle trapped an inert gas in the closed end of the test tube with a column of mercury, thereby making the number of particles and the temperature constant. He observed that when the pressure was increased in the gas, by adding more mercury to the column, the trapped gas' volume decreased (this is known as an inverse relationship). Furthermore, when Boyle multiplied the pressure and volume of each observation, the product was constant. This relationship held for every gas that Boyle observed leading to the law, (PV=k), named to honor his work in this field.
There are many mathematical tools available for analyzing gas properties. As gases are subjected to extreme conditions, these tools become more complex, from the Euler equations for inviscid flow to the Navier–Stokes equations that fully account for viscous effects. These equations are adapted to the conditions of the gas system in question. Boyle's lab equipment allowed the use of algebra to obtain his analytical results. His results were possible because he was studying gases in relatively low pressure situations where they behaved in an "ideal" manner. These ideal relationships apply to safety calculations for a variety of flight conditions on the materials in use. The high technology equipment in use today was designed to help us safely explore the more exotic operating environments where the gases no longer behave in an "ideal" manner. This advanced math, including statistics and multivariable calculus, makes possible the solution to such complex dynamic situations as space vehicle reentry. An example is the analysis of the space shuttle reentry pictured to ensure the material properties under this loading condition are appropriate. In this flight regime, the gas is no longer behaving ideally. | 7 | Physical Chemistry |
The technology works by probing an optical standing wave, or the sum of the standing waves in the case of polychromatic light, created by a light to be analyzed. In a SWIFTS linear configuration (true Lippman configuration), the stationary wave is created by a single-mode waveguide ended by a fixed mirror. The stationary wave is regularly sampled on one side of a waveguide using nano-scattering dots. These dots are located in the evanescent field. These nanodots are characterized by an optical index difference with the medium in which the evanescent field is located. The light is then scattered around an axis perpendicular to the waveguide. For each dot, this scattered light is detected by a pixel aligned with this axis. The intensity detected is therefore proportional to the intensity inside the waveguide at the exact location of the dot. This results in a linear image of the interferogram. No moving parts are used. A mathematical function known as a Lippmann transform, similar to a Fourier transform, is then applied to this linear image and gives the spectrum of the light.
The interferogram is truncated. Only the frequencies corresponding to the zero optical path difference at the mirror, up to the farthest dots are sampled. Higher frequencies are rejected. This interferogram’s truncation determines the spectral resolution. The interferogram is undersampled. A consequence of this under-sampling is a limitation of the wavelength bandwidth to which the mathematical function is applied.
SWIFTS technology displays the Fellgetts advantage, which is derived from the fact that an interferometer measures wavelengths simultaneously with the same elements of the detector, whereas a dispersive spectrometer measures them successively. Fellgetts advantage also states that when collecting a spectrum whose measurement noise is dominated by detector noise, a multiplex spectrometer such as a Fourier-transform spectrometer will produce a relative improvement in the signal-to-noise ratio, with respect to an equivalent scanning monochromator, that is approximately equal to the square root of the number of sample points comprising the spectrum. The Connes advantage states that the wavenumber scale of an interferometer, derived from a helium–neon laser, is more accurate and boasts better long-term stability than the calibration of dispersive instruments. | 7 | Physical Chemistry |
There are limited examples of small molecules that target RNA and are approved drugs for the treatment of human disease. Ribavirin was approved in 2002 to treat Hepatitis C and viral hemorrhagic fever. As a nucleoside inhibitor, the guanosine analog prodrug is used to stop viral RNA synthesis and viral mRNA capping by incorporating into RNA and pairing to uracil or cytosine. Branaplam is currently in phase I/II clinical trial for the treatment of Spinal Muscular Atrophy (SMA). This molecule is from a class of pyridazine small molecules and enhances the inclusion of exon 7, resulting in a full-length and functional protein product.
Branaplam represents the first mechanistic study of splicing modulation using a sequence-selective small molecule. The drug stabilizes the transient double-stranded RNA (dsRNA) structure formed between the SMN2 pre-mRNA and U1 snRNP complex, a key component of the splicesome. Further, this compound acts by increasing the binding affinity of U1 snRNP to the 5’ splice site (5’ss) in a sequence-selective manner that is discrete from constitutive recognition. Ataluren is in clinical trials for the treatment of Duchenne Muscular Dystrophy (DMD). It is believed that Ataluren acts by promoting insertion of near-cognate tRNAs at the site of the nonsense codon without affecting transcription, mRNA processing, mRNA stability, or protein stability to give nonsense suppression. This drug would be effective for ~10% of patients with DMD who have a single mutation in the DMD gene causing a stop codon to appear prematurely (nonsense mutation). | 1 | Biochemistry |
All family members are capable of catalyzing the hydrolysis of PIP, a phosphatidylinositol at the inner leaflet of the plasma membrane into the two second messengers, inositol trisphosphate (IP) and diacylglycerol (DAG).
The chemical reaction may be expressed as:
:1-phosphatidyl-1-myo-inositol 4,5-bisphosphate + HO -myo-inositol 1,4,5-trisphosphate + diacylglycerol
PLCs catalyze the reaction in two sequential steps. The first reaction is a phosphotransferase step that involves an intramolecular attack between the hydroxyl group at the 2 position on the inositol ring and the adjacent phosphate group resulting in a cyclic IP intermediate. At this point, DAG is generated. However, in the second phosphodiesterase step, the cyclic intermediate is held within the active site long enough to be attacked by a molecule of water, resulting in a final acyclic IP product. It should be mentioned that bacterial forms of the enzyme, which contain only the catalytic lipase domain, produce cyclic intermediates exclusively, whereas the mammalian isoforms generate predominantly the acyclic product. However, it is possible to alter experimental conditions (e.g., temperature, pH) in vitro' such that some mammalian isoforms will alter the degree to which they produce mixtures of cyclic/acyclic products along with DAG. This catalytic process is tightly regulated by reversible phosphorylation of different phosphoinositides and their affinity for different regulatory proteins. | 1 | Biochemistry |
Non-aqueous acid–base titrations can be carried out advantageously by thermometric means.
Acid leach solutions from some copper mines can contain large quantities of Fe(III) as well as Cu(II). The "free acid" (sulfuric acid) content of these leach solutions is a critical process parameter. While thermometric titrimetry can determine the free acid content with modest amounts of Fe(III), in some solutions the Fe(III) content is so high as to cause serious interference. Complexation with necessarily large amounts of oxalate is undesirable due to the toxicity of the reagent. A thermometric titration was devised by diluting the aliquot with propan-2-ol and titration with standard KOH in propan-2-ol. Most of the metal content precipitated prior to the commencement of the titration, and a clear, sharp endpoint for the sulfuric acid content was obtained. | 3 | Analytical Chemistry |
In association football, the ball is predominantly struck by the foot. Footedness may refer to the foot a player uses to kick with the greatest force and skill. Most people are right-footed, kicking with the right leg. Capable left-footed footballers are rare and therefore quite sought after. As rare are "two-footed" players, who are equally capable with both feet. Such players make up only one sixth of players in the top professional leagues in Europe. Two-footedness can be learnt, a notable case being England international Tom Finney, but can only be properly developed in the early years. In Australian Rules Football, several players are equally adept at using both feet to kick the ball, such as Sam Mitchell and Charles Bushnell (footballer, retired).
In basketball, a sport composed almost solely of right-handed players, it is common for most athletes to have a dominant left leg which they would use when jumping to complete a right-hand layup. Hence, left-handed basketball players tend to use their right leg more as they finish a left handed layup (although both right- and left-handed players are usually able to use both hands when finishing near the basket).
In the National Football League, a disproportionate, and increasing, number of punters punt with their left leg, where punting is the position in play that receives and kicks the ball once it leaves the line of scrimmage. At the end of the 2017 NFL season, 10 out of the league's 32 punters were left-footed, up from four out of 31 (not counting dual-footed punter Chris Hanson, who left the league in 2009) at the beginning of the millennium; in contrast, placekickers were almost exclusively right-footed. The only apparent advantage to punting with the left foot is that, because it is not as common, return specialists are not as experienced handling the ball spinning in the opposite direction. | 4 | Stereochemistry |
In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory. It has particular value for analyzing delocalized electrons where the bonding cannot be expressed by one single Lewis structure. The resonance hybrid is the accurate structure for a molecule or ion; it is an average of the theoretical contributing structures. | 7 | Physical Chemistry |
Corrosion inhibitors are substances used in the oil industry to protect equipment and pipes against corrosion. Corrosion is a common problem in the oil industry due to the presence of water, gases, and other corrosive contaminants in the production environment.
Anodic inhibitors and cathodic inhibitors are the two main categories of corrosion inhibitors. While cathodic inhibitors act as catalysts to slow down corrosion, anodic inhibitors protect metal surfaces by acting as physical barriers. They can also be divided into organic and inorganic corrosion inhibitors based on their chemical composition.
Corrosion inhibitors are used in the petroleum industry in several steps, including drilling, production, transportation, and storage of oil and gas. They can mitigate different types of corrosion in the petroleum industry, such as generalized corrosion, pitting corrosion, erosion corrosion, stress corrosion, galvanic corrosion, cavitation corrosion, and hydrogen blister. | 0 | Organic Chemistry |
Main methods to study protein–ligand interactions are principal hydrodynamic and calorimetric techniques, and principal spectroscopic and structural methods such as
*Fourier transform spectroscopy
*Raman spectroscopy
*Fluorescence spectroscopy
*Circular dichroism
*Nuclear magnetic resonance
*Mass spectrometry
*Atomic force microscope
*Paramagnetic probes
*Dual polarisation interferometry
*Multi-parametric surface plasmon resonance
*Ligand binding assay and radioligand binding assay
Other techniques include:
fluorescence intensity,
bimolecular fluorescence complementation,
FRET (fluorescent resonance energy transfer) / FRET quenching
surface plasmon resonance,
bio-layer interferometry,
Coimmunopreciptation
indirect ELISA,
equilibrium dialysis,
gel electrophoresis,
far western blot,
fluorescence polarization anisotropy,
electron paramagnetic resonance,
microscale thermophoresis,
switchSENSE.
The dramatically increased computing power of supercomputers and personal computers has made it possible to study protein–ligand interactions also by means of computational chemistry. For example, a worldwide grid of well over a million ordinary PCs was harnessed for cancer research in the project grid.org, which ended in April 2007. Grid.org has been succeeded by similar projects such as World Community Grid, Human Proteome Folding Project, Compute Against Cancer and Folding@Home. | 1 | Biochemistry |
Willard was born on June 3, 1881, in Erie, Pennsylvania. His family relocated to Union City, Michigan, in 1883 and he spent the rest of his early life there. His father and later his high school teachers encouraged his interest in chemistry, which he pursued as an undergraduate at the University of Michigan. He received his A.B. in 1903 and his M.A. in 1905. Meanwhile, he was briefly hired as an instructor of chemistry, but at the encouragement of coworkers he decided to pursue his Ph.D. at Harvard University. He received his Ph.D. in 1909 under the supervision of Theodore William Richards. | 3 | Analytical Chemistry |
For a cell reaction characterized by the chemical equation:
at constant temperature and pressure, the thermodynamic voltage (minimum voltage required to drive the reaction) is given by the Nernst equation:
where is the Gibbs energy and F is the Faraday constant. The standard thermodynamic voltage (i.e. at standard temperature and pressure) is given by:
and the Nernst equation can be used to calculate the standard potential at other conditions.
The cell reaction is generally endothermic: i.e. it will extract heat from its environment. The Gibbs energy calculation generally assumes an infinite thermal reservoir to maintain a constant temperature, but in a practical case, the reaction will cool the electrode interface and slow the reaction occurring there.
If the cell voltage is increased above the thermodynamic voltage, the product of that voltage and the current will generate heat, and if the voltage is such that the heat generated matches the heat required by the reaction to maintain a constant temperature, that voltage is called the "thermoneutral voltage". The rate of delivery of heat is equal to where T is the temperature (the standard temperature, in this case) and dS/dt is the rate of entropy production in the cell. At the thermoneutral voltage, this rate will be zero, which indicates that the thermoneutral voltage may be calculated from the enthalpy. | 7 | Physical Chemistry |
Smeltmills were water-powered mills used to smelt lead or other metals.
The older method of smelting lead on wind-blown bole hills began to be superseded by artificially-blown smelters. The first such furnace was built by Burchard Kranich at Makeney, Derbyshire in 1554, but produced less good lead than the older bole hill. William Humfrey (the Queen's assay master), and a leading shareholder in the Company of Mineral and Battery Works introduced the ore hearth from the Mendips about 1577. This was initially blown by a foot-blast, but was soon developed into a water-powered smelt mill at Beauchief (now a suburb of Sheffield).
A typical smelt mill had an orehearth and a slaghearth, the latter being used to reprocess slags from the orehearth in order to recover further lead from the slag | 8 | Metallurgy |
Dye-sensitized solar cells or DSSCs use TiO and dyes to absorb the light. This absorption induces the formation of electron-hole pairs which are used to oxidize and reduce the same redox couple, usually I/I. Consequently, a differential potential is created which induces a current. | 5 | Photochemistry |
It was first observed by accident by Mike Marchywka while trying to find a selective means to etch non-diamond carbon and fabricate simple astronomical UV detection devices. These devices required a few specific features such as clean surfaces and patterned areas of non-diamond carbon but the approach has subsequently been explored as a more general means to terminate carbon surfaces and selectively clean and etch various other materials or structures. The term "Marchywka effect" is not used consistently and sometimes the term "bipolar surface treatment" is used as the substrate is induced to become a bipolar electrode. Various phrases such as "non-contacted electrochemical" process may also be used (see any references cited herein) or it may be mentioned as just an "electrochemical etch".
While this is easily confused with various common electrochemical cells, and may appear to be a trivial and obvious extension of well known methods, recent patents continue to reference prior work that cites non-contactedness as a feature. The use of a low conductivity medium as used in Marchywka et al.'s original paper is sometimes noted when it is used and may produce new effects.
The apparatus to create the effect is similar to the well-known electroporation system except that the biological specimen is replaced with an inorganic substrate, although, in some cases, organic films can be etched with this process using a surfactant solution as the electrolyte. | 7 | Physical Chemistry |
Rhamnolipids have long been reported to have antimicrobial properties. They have been shown to have activity against a range of bacteria including Serratia marcescens, Klebsiella pneumoniae, Staphylococcus aureus and Bacillus subtilis with minimum inhibitory concentrations (MICs) ranging from 0.5 µg/mL to 32 µg/mL. Activity against several fungi such as Fusarium solani and Penicillium funiculosum have also been observed with MICs of 75 µg/mL and 16 µg/mL respectively. Rhamnolipids have been suggested as antimicrobials able to remove Bordetella bronchiseptica biofilms. The mode of killing has been shown to result from intercalation of rhamnolipids into the cell membrane causing pores to form which result in cell lysis, at least in the case of Bacillus subtilis. The anti-microbial action of rhamnolipids may provide a fitness advantage for Pseudomonas aeruginosa by excluding other microorganisms from the colonised niche. Furthermore, rhamnolipids have been shown to have anti-viral and zoosporicidal activities. The antimicrobial properties of rhamnolipids may confer a fitness advantage for Pseudomonas aeruginosa in niche colonisation as Pseudomonas aeruginosa is a soil bacterium, as well as competing with other bacteria in the cystic fibrosis lung. | 0 | Organic Chemistry |
Ommochrome (or visual pigment) refers to several biological pigments that occur in the eyes of crustaceans and insects. The eye color is determined by the ommochromes. Ommochromes are also found in the chromatophores of cephalopods, and in spiders.
Ommochromes are metabolites of tryptophan, via kynurenine and 3-hydroxykynurenine. They are responsible for a wide variety of colors, ranging from yellow over red and brown to black. Lighter colors tend to be generated by ommatins, while mixtures of ommatin and ommins are responsible for darker colors.
In spiders, ommochromes are usually deposited as pigment granules within the cells of the hypodermis, immediately beneath the cuticle.
A study on various insects showed that ommochromes in their eyes have high antioxidant activity. The ommochromes were found to have the ability to suppress the Maillard reaction. | 1 | Biochemistry |
The Greenhouse Gases Observing Satellite-2 (GOSAT-2), also known as , is an Earth observation satellite dedicated to greenhouse gas monitoring. It is a successor of Greenhouse Gases Observing Satellite (GOSAT). The GOSAT-2 was developed as a joint project of the Japan Aerospace Exploration Agency (JAXA), Ministry of the Environment, and the National Institute for Environmental Studies (NIES). It was launched on 29 October 2018 from the Tanegashima Space Center aboard the H-IIA rocket. | 2 | Environmental Chemistry |
When an Arabidopsis plant is subjected to cold temperatures, it induces cold response genes. In order for cold genes to be expressed, COLD1 receptors that are present on the plants surface sense the cold temperature and activate Ca channels, these channels include: MCA1, MCA2 and other undetermined channels. The activation of Ca channels allows for Ca to move into the cell and increase cellular Ca concentration. The concentration and duration of Ca within the cell is determined by the plants acclimation to the temperature, as well as the intensity and length of cold duration. During increased Ca concentrations, Ca is used as a second messenger to increase the concentration of Ca dependent protein kinase (CPKs). During times of increased Ca concentrations, Ca also binds to calmodulin on the CRLK and AtSR1/CAMTA3. Activation of the CRLK causes an MAPK cascade that activates the MAPK pathway, signaling for the suppression of ICE1 degradation: ICE1 encodes a transcription factor that promotes production of CBF/DREB genes. AtSR1 also binds to the promoter region of CBF and promotes CBF gene expression. CBF and DREB transcription proteins are then synthesized and bind to the promoter of cold induced genes DRE and CRT. Binding to the promoter region of the cold induced genes increases the rate of transcription of cold genes, allowing the Arabidopsis plant to become more acclimated to the cold. This Ca signaling cascade, and transcription of cold genes in response to cold temperatures, allows for the plants survival. | 7 | Physical Chemistry |
Fluoroform was first obtained by Maurice Meslans in the violent reaction of iodoform with dry silver fluoride in 1894. The reaction was improved by Otto Ruff by substitution of silver fluoride by a mixture of mercury fluoride and calcium fluoride. The exchange reaction works with iodoform and bromoform, and the exchange of the first two halogen atoms by fluorine is vigorous. By changing to a two step process, first forming a bromodifluoromethane in the reaction of antimony trifluoride with bromoform and finishing the reaction with mercury fluoride the first efficient synthesis method was found by Henne. | 2 | Environmental Chemistry |
The biological pump, in its simplest form, is the ocean's biologically driven sequestration of carbon from the atmosphere to the ocean interior and seafloor sediments. It is the part of the oceanic carbon cycle responsible for the cycling of organic matter formed mainly by phytoplankton during photosynthesis (soft-tissue pump), as well as the cycling of calcium carbonate (CaCO) formed into shells by certain organisms such as plankton and mollusks (carbonate pump).
The biological pump can be divided into three distinct phases, the first of which is the production of fixed carbon by planktonic phototrophs in the euphotic (sunlit) surface region of the ocean. In these surface waters, phytoplankton use carbon dioxide (CO), nitrogen (N), phosphorus (P), and other trace elements (barium, iron, zinc, etc.) during photosynthesis to make carbohydrates, lipids, and proteins. Some plankton, (e.g. coccolithophores and foraminifera) combine calcium (Ca) and dissolved carbonates (carbonic acid and bicarbonate) to form a calcium carbonate (CaCO) protective coating.
Once this carbon is fixed into soft or hard tissue, the organisms either stay in the euphotic zone to be recycled as part of the regenerative nutrient cycle or once they die, continue to the second phase of the biological pump and begin to sink to the ocean floor. The sinking particles will often form aggregates as they sink, greatly increasing the sinking rate. It is this aggregation that gives particles a better chance of escaping predation and decomposition in the water column and eventually make it to the sea floor.
The fixed carbon that is either decomposed by bacteria on the way down or once on the sea floor then enters the final phase of the pump and is remineralized to be used again in primary production. The particles that escape these processes entirely are sequestered in the sediment and may remain there for millions of years. It is this sequestered carbon that is responsible for ultimately lowering atmospheric CO.
* Brum JR, Morris JJ, Décima M and Stukel MR (2014) "Mortality in the oceans: Causes and consequences". Eco-DAS IX Symposium Proceedings, Chapter 2, pages 16–48. Association for the Sciences of Limnology and Oceanography. .
* Mateus, M.D. (2017) "Bridging the gap between knowing and modeling viruses in marine systems—An upcoming frontier". Frontiers in Marine Science, 3: 284.
* Beckett, S.J. and Weitz, J.S. (2017) "Disentangling niche competition from grazing mortality in phytoplankton dilution experiments". PLOS ONE, 12(5): e0177517. . | 9 | Geochemistry |
FRET can be used to observe membrane fluidity, movement and dispersal of membrane proteins, membrane lipid-protein and protein-protein interactions, and successful mixing of different membranes. FRET is also used to study formation and properties of membrane domains and lipid rafts in cell membranes and to determine surface density in membranes. | 1 | Biochemistry |
Hubel majored in mechanical engineering at Iowa State University, graduating in 1983. She continued her studies at the Massachusetts Institute of Technology (MIT), where she earned a master's degree in 1989 and completed her Ph.D. in the same year.
She worked as a research fellow at Massachusetts General Hospital from 1989 to 1990, and as an instructor at MIT from 1990 to 1993, before moving to the University of Minnesota in 1993 as a research associate in the Department of Laboratory Medicine and Pathology. In 1996 she became an assistant professor in that department, and in 2002 she moved to the Department of Mechanical Engineering as an associate professor. She was promoted to full professor in 2009, and became director of the Biopreservation Core Resource in 2010.
With two of her students, she founded a spinoff company, BlueCube Bio (later renamed Evia Bio) to commercialize their technology for preserving cells in cell therapy. She continues to serve as chief scientific officer for Evia Bio.
She became president-elect of the Society for Cryobiology for the 2022–2023 term, and will become president in the subsequent term. | 1 | Biochemistry |
* Orbifold signature:
* Coxeter notation (rhombic): [∞,2,∞]
* Coxeter notation (square): [(4,4,2)]
* Lattice: rhombic
* Point group: D
* The group cmm has reflections in two perpendicular directions, and a rotation of order two (180°) whose centre is not on a reflection axis. It also has two rotations whose centres are on a reflection axis.
*This group is frequently seen in everyday life, since the most common arrangement of bricks in a brick building (running bond) utilises this group (see example below).
The rotational symmetry of order 2 with centres of rotation at the centres of the sides of the rhombus is a consequence of the other properties.
The pattern corresponds to each of the following:
*symmetrically staggered rows of identical doubly symmetric objects
*a checkerboard pattern of two alternating rectangular tiles, of which each, by itself, is doubly symmetric
*a checkerboard pattern of alternatingly a 2-fold rotationally symmetric rectangular tile and its mirror image
;Examples of group cmm | 3 | Analytical Chemistry |
Combining PDRCs with other systems may increase their cooling power. When included in a combined thermal insulation, evaporative cooling, and radiative cooling system consisting of "a solar reflector, a water-rich and IR-emitting evaporative layer, and a vapor-permeable, IR-transparent, and solar-reflecting insulation layer," 300% higher ambient cooling power was demonstrated. This could extend the shelf life of food by 40% in humid climates and 200% in dry climates without refrigeration. The system however requires water "re-charges" to maintain its cooling power, with more frequent re-charges in hot climates than cooler climates.
A dual-mode asymmetric photonic mirror (APM) consisting of silicon-based diffractive gratings could achieve all-season cooling, even under cloudy and humid conditions, as well as heating. The cooling power of APM could perform 80% more when compared to standalone radiative coolers. Under cloudy sky, it could achieve 8 °C more cooling and, for heating, 5.7 °C higher. | 7 | Physical Chemistry |
* An ingredient in diesel exhaust fluid (DEF), which is 32.5% urea and 67.5% de-ionized water. DEF is sprayed into the exhaust stream of diesel vehicles to break down dangerous emissions into harmless nitrogen and water.
* A component of animal feed, providing a relatively cheap source of nitrogen to promote growth
* A non-corroding alternative to rock salt for road de-icing. It is often the main ingredient of pet friendly salt substitutes although it is less effective than traditional rock salt or calcium chloride.
* A main ingredient in hair removers such as Nair and Veet
* A browning agent in factory-produced pretzels
* An ingredient in some skin cream, moisturizers, hair conditioners, and shampoos
* A cloud seeding agent, along with other salts
* A flame-proofing agent, commonly used in dry chemical fire extinguisher charges such as the urea-potassium bicarbonate mixture
* An ingredient in many tooth whitening products
* An ingredient in dish soap
* Along with diammonium phosphate, as a yeast nutrient, for fermentation of sugars into ethanol
* A nutrient used by plankton in ocean nourishment experiments for geoengineering purposes
* As an additive to extend the working temperature and open time of hide glue
* As a solubility-enhancing and moisture-retaining additive to dye baths for textile dyeing or printing
* As an optical parametric oscillator in nonlinear optics | 0 | Organic Chemistry |
Another approach to prevent or reduce PD formation is by modifying the primers so that annealing with themselves or each other does not cause extension.
HANDS (Homo-Tag Assisted Non-Dimer System): a nucleotide tail, complementary to the 3 end of the primer is added to the 5 end of the primer. Because of the close proximity of the 5 tail it anneals to the 3 end of the primer. The result is a stem-loop primer that excludes annealing involving shorter overlaps, but permits annealing of the primer to its fully complementary sequence in the target.
Chimeric primers: some DNA bases in the primer are replaced with RNA bases, creating a chimeric sequence. The melting temperature of a chimeric sequence with another chimeric sequence is lower than that of chimeric sequence with DNA. This difference enables setting the annealing temperature such that the primer will anneal to its target sequence, but not to other chimeric primers.
Blocked-cleavable primers: a method known as RNase H-dependent PCR (rhPCR), utilizes a thermostable RNase HII to remove a blocking group from the PCR primers at high temperature. This RNase HII enzyme displays almost no activity at low temperature, making the removal of the block only occur at high temperature. The enzyme also possess inherent primer:template mismatch discrimination, resulting in additional selection against primer-dimers.
Self-Avoiding molecular recognition systems :also known as SAMRS, eliminating primer dimers by introducing nucleotide analogues T*, A*, G* and C* into the primer. The SAMRS DNA could bind to natural DNA, but not to other members of the same SAMRS species. For example, T* could bind to A but not A*, and A* could bind to T but not T*. Thus, through careful design, primers build from SAMRS could avoid primer-primer interactions and allowing sensitive SNP detection as well as multiplex PCR. | 1 | Biochemistry |
The most common carotenoids include lycopene and the vitamin A precursor β-carotene. In plants, the xanthophyll lutein is the most abundant carotenoid and its role in preventing age-related eye disease is currently under investigation. Lutein and the other carotenoid pigments found in mature leaves are often not obvious because of the masking presence of chlorophyll. When chlorophyll is not present, as in autumn foliage, the yellows and oranges of the carotenoids are predominant. For the same reason, carotenoid colors often predominate in ripe fruit after being unmasked by the disappearance of chlorophyll.
Carotenoids are responsible for the brilliant yellows and oranges that tint deciduous foliage (such as dying autumn leaves) of certain hardwood species as hickories, ash, maple, yellow poplar, aspen, birch, black cherry, sycamore, cottonwood, sassafras, and alder. Carotenoids are the dominant pigment in autumn leaf coloration of about 15-30% of tree species. However, the reds, the purples, and their blended combinations that decorate autumn foliage usually come from another group of pigments in the cells called anthocyanins. Unlike the carotenoids, these pigments are not present in the leaf throughout the growing season, but are actively produced towards the end of summer. | 5 | Photochemistry |
Chiral crown stationary phases consist Crown ethers, immobilized or bonded to the support particles, are polyethers with a macrocyclic structure that can create host-guest complexes with alkali, earth-alkali metal ions, and ammonium cations. The skeleton of the cyclic structure is composed of oxygen and methylene groups arranged alternately. The electron-donating ether oxygens are positioned within the inner wall of the crown cavity, and are encircled by methylene groups in a collar-like arrangement. The chiral recognition is based on two distinct diastereomeric inclusion complexes that can be generated. The primary interactions facilitating complexation involve hydrogen bonds, formed between the three amine hydrogens and the oxygens of the macrocyclic ether, arranged in a tripod configuration. Additionally, ionic interactions, dipole-dipole interactions, or hydrogen bonds can occur between the carbocyclic groups and polar groups of the analytes, providing further support for the complexes. | 4 | Stereochemistry |
Some oxidative additions proceed analogously to the well known bimolecular nucleophilic substitution reactions in organic chemistry. Nucleophilic attack by the metal center at the less electronegative atom in the substrate leads to cleavage of the R–X bond, to form an [M–R] species. This step is followed by rapid coordination of the anion to the cationic metal center. For example, reaction of a square planar complex with methyl iodide:
This mechanism is often assumed in the addition of polar and electrophilic substrates, such as alkyl halides and halogens. | 0 | Organic Chemistry |
Tenebrescence, also known as reversible photochromism, is the ability of minerals to change color when exposed to light. The effect can be repeated indefinitely, but is destroyed by heating.
Tenebrescent minerals include hackmanite, spodumene and tugtupite. | 5 | Photochemistry |
Chemotaxis receptors are expressed in the surface membrane with diverse dynamics, some of them have long-term characteristics as they are determined genetically, others have short-term moiety as their assembly is induced ad hoc in the presence of the ligand. The diverse feature of the chemotaxis receptors and ligands provides the possibility to select chemotactic responder cells with a simple chemotaxis assay. By chemotactic selection we can determine whether a still not characterized molecule acts via the long- or the short-term receptor pathway. Recent results proved that chemokines (e.g. IL-8, RANTES) are working on long-term chemotaxis receptors, while vasoactive peptides (e.g. endothelin) act more on the short-term ones. Term chemotactic selection is also used to design a technique which separates eukaryotic or prokaryotic cells upon their chemotactic responsiveness to selector ligands. | 1 | Biochemistry |
The process of forming diazonium compounds is called "diazotation", "diazoniation", or "diazotization". The reaction was first reported by Peter Griess in 1858, who subsequently discovered several reactions of this new class of compounds. Most commonly, diazonium salts are prepared by treatment of aromatic amines with nitrous acid and additional acid. Usually the nitrous acid is generated in situ (in the same flask) from sodium nitrite and the excess mineral acid (usually aqueous HCl, , p-, or ):
Chloride salts of diazonium cation, traditionally prepared from the aniline, sodium nitrite, and hydrochloric acid, are unstable at room temperature and are classically prepared at 0 – 5 °C. However, one can isolate diazonium compounds as tetrafluoroborate or tosylate salts, which are stable solids at room temperature. It is often preferred that the diazonium salt remain in solution, but they do tend to supersaturate. Operators have been injured or even killed by an unexpected crystallization of the salt followed by its detonation.
Due to these hazards, diazonium compounds are often not isolated. Instead they are used in situ. This approach is illustrated in the preparation of an arenesulfonyl compound: | 0 | Organic Chemistry |
Different assembly tools have been developed to handle jumping library data. One example is DELLY. DELLY was developed to discover genomic structural variants and "integrates short insert paired-ends, long-range mate-pairs and split-read alignments" to detect rearrangements at sequence level.
An example of joint development of new experimental design and algorithm development is demonstrated by the ALLPATHS-LG assembler. | 1 | Biochemistry |
By NIGMS program mandate, Glue Grant consortia must contain core resources and bridging projects. The EFI consists of six scientific cores which provide bioinformatic, structural, computational, and data management expertise to facilitate functional predictions for enzymes of unknown function targeted by the EFI. At the beginning of the grant, these predictions were tested by five Bridging Projects representing the amidohydrolase, enolase, GST, HAD, and isoprenoid synthase enzyme superfamilies. Three Bridging Projects now remain. In addition, the Anaerobic Enzymology Pilot Project was added in 2014 to explore the Radical SAM superfamily and Glycyl Radical Enzyme superfamily. | 1 | Biochemistry |
The suppressor of cytokine signaling 1 has been shown to interact with:
* Tax,
* CD117,
* Colony stimulating factor 1 receptor
* Growth hormone receptor,
* IRS2,
* Janus kinase 2, and
* TEC. | 1 | Biochemistry |
The asymmetric hydrogenation of indoles has been established with N-Boc protection.
<br />
A Pd(TFA)/H8-BINAP system achieves the enantioselective cis-hydrogenation of 2,3- and 2-substituted indoles.
<br />
Akin to the behavior of indoles, pyrroles can be converted to pyrrolidines by asymmetric hydrogenation.
<br /> | 0 | Organic Chemistry |
Cyanobacteria, the precursor to chloroplasts found in green plants, have both photosystems with both types of reaction centers. Combining the two systems allows for producing oxygen. | 5 | Photochemistry |
:DNA strand 1: antisense strand (transcribed to) → RNA strand (sense)
:DNA strand 2: sense strand
Some regions within a double-stranded DNA molecule code for genes, which are usually instructions specifying the order in which amino acids are assembled to make proteins, as well as regulatory sequences, splicing sites, non-coding introns, and other gene products. For a cell to use this information, one strand of the DNA serves as a template for the synthesis of a complementary strand of RNA. The transcribed DNA strand is called the template strand, with antisense sequence, and the mRNA transcript produced from it is said to be sense sequence (the complement of antisense). The untranscribed DNA strand, complementary to the transcribed strand, is also said to have sense sequence; it has the same sense sequence as the mRNA transcript (though T bases in DNA are substituted with U bases in RNA).
The names assigned to each strand actually depend on which direction you are writing the sequence that contains the information for proteins (the "sense" information), not on which strand is depicted as "on the top" or "on the bottom" (which is arbitrary). The only biological information that is important for labeling strands is the relative locations of the terminal 5′ phosphate group and the terminal 3′ hydroxyl group (at the ends of the strand or sequence in question), because these ends determine the direction of transcription and translation. A sequence written 5′-CGCTAT-3′ is equivalent to a sequence written 3′-TATCGC-5′ as long as the 5′ and 3′ ends are noted. If the ends are not labeled, convention is to assume that both sequences are written in the 5′-to-3′ direction. The "Watson strand" refers to 5′-to-3′ top strand (5′→3′), whereas the "Crick strand" refers to the 5′-to-3′ bottom strand (3′←5′). Both Watson and Crick strands can be either sense or antisense strands depending on the specific gene product made from them.
For example, the notation "YEL021W", an alias of the URA3 gene used in the National Center for Biotechnology Information (NCBI) database, denotes that this gene is in the 21st open reading frame (ORF) from the centromere of the left arm (L) of Yeast (Y) chromosome number V (E), and that the expression coding strand is the Watson strand (W). "YKL074C" denotes the 74th ORF to the left of the centromere of chromosome XI and that the coding strand is the Crick strand (C). Another confusing term referring to "Plus" and "Minus" strand is also widely used. Whether the strand is sense (positive) or antisense (negative), the default query sequence in NCBI BLAST alignment is "Plus" strand. | 1 | Biochemistry |
An alternate preparation of carbonate green rust first creates a suspension of iron(III) hydroxide () in an iron(II) chloride solution, and bubbles carbon dioxide through it.
In a more recent variant, solutions of both iron(II) and iron(III) salts are first mixed, then a solution of is added, all in the stoichometric proportions of the desired green rust. No oxidation step is then necessary. | 8 | Metallurgy |
Measuring cardiac biomarkers can be a step toward making a diagnosis for a condition. Whereas cardiac imaging often confirms a diagnosis, simpler and less expensive cardiac biomarker measurements can advise a physician whether more complicated or invasive procedures are warranted. In many cases medical societies advise doctors to make biomarker measurements an initial testing strategy especially for patients at low risk of cardiac death.
Many acute cardiac marker IVD products are targeted at nontraditional markets, e.g., the hospital ER instead of traditional hospital or clinical laboratory environments. Competition in the development of cardiac marker diagnostic products and their expansion into new markets is intense.
Recently, the intentional destruction of myocardium by alcohol septal ablation has led to the identification of additional potential markers. | 1 | Biochemistry |
The force F(h) between two bodies is related to the interaction free energy U(h) as
where h is the surface-to-surface separation. Conversely, when the force profile is known, one can evaluate the interaction energy as
When one considers two planar walls, the corresponding quantities are expressed per unit area. The disjoining pressure is the force per unit area and can be expressed by the derivative
where W(h) is the surface free energy per unit area. Conversely, one has
The main restriction of the Derjaguin approximation is that it is only valid at distances much smaller than the size of the objects involved, namely h ≪ R and h ≪ R. Furthermore, it is a continuum approximation and thus valid at distances larger than the molecular length scale. Even when rough surfaces are involved, this approximation has been shown to be valid in many situations. Its range of validity is restricted to distances larger than the characteristic size of the surface roughness features (e.g., root mean square roughness). | 7 | Physical Chemistry |
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