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These forms of AC have been reported in specific bacteria (Prevotella ruminicola and Rhizobium etli , respectively) and have not been extensively characterized. There are a few extra members (~400 in Pfam) known to be in class VI. Class VI enzymes possess a catalytic core similar to the one in Class III. | 1 | Applied and Interdisciplinary Chemistry |
Lanthanum(III) oxide, also known as lanthana, chemical formula , is an inorganic compound containing the rare earth element lanthanum and oxygen. It is used in some ferroelectric materials, as a component of optical materials, and is a feedstock for certain catalysts, among other uses. | 0 | Theoretical and Fundamental Chemistry |
A composite cross population (CCP) is created by crossing a number of plants from different lines, and subsequently bulking seeds from the resulting offspring. This makes a CCP a population of plants with a lot of inherent genetic diversity, in contrast to monocultures where all plants are clones and homozygous at all loci (fully inbred). In recent years CCPs have been proposed as a way to create modern landraces of wheat, barley and oats. Research is done to explore whether they are better suited for organic farming than the modern cultivars.
They are suited for participatory breeding of crops, which is in contrast to cultivars owned by big breeding companies.
The idea of using CCPs in plant breeding was published in 1956 based on the barley composite cross devised by Harry Harlan and Mary Martini in 1929. Yield data for 4 different populations for 8–28 years were presented in the article and after 8–15 years of repeated breeding under natural selection, the populations out-yielded the reference cultivar. | 1 | Applied and Interdisciplinary Chemistry |
For the Eulerian velocity as a monochromatic wave of any nature in a continuous medium: one readily obtains by the perturbation theory with as a small parameter for the particle position
Here the last term describes the Stokes drift velocity | 1 | Applied and Interdisciplinary Chemistry |
Sulfide deposition within the trap zone occurs when metal-carrying sulfate, sulfide, or other complexes become chemically unstable due to one or more of the following processes;
*falling temperature, which renders the complex unstable or metal insoluble
*loss of pressure, which has the same effect
*reaction with chemically reactive wall rocks, usually of reduced oxidation state, such as iron-bearing rocks, mafic or ultramafic rocks, or carbonate rocks
*degassing of the hydrothermal fluid into a gas and water system, or boiling, which alters the metal carrying capacity of the solution and even destroys metal-carrying chemical complexes
Metal can also precipitate when temperature and pressure or oxidation state favour different ionic complexes in the water, for instance the change from sulfide to sulfate, oxygen fugacity, exchange of metals between sulfide and chloride complexes, et cetera. | 0 | Theoretical and Fundamental Chemistry |
When using different types of microspheres, SAT is capable of simultaneously testing multiple variables, such as DNA and proteins, in a given sample. This allows SAT to analyze variety of molecular targets during a single reaction. The common nucleic acid detection method includes direct DNA hybridization. The direct DNA hybridization approach is the simplest suspension array assay whereby 15 to 20 bp DNA oligonucleotides attached to microspheres are amplified using PCR. This is the optimized probe length as it minimizes the melting temperature variation among different probes during probe-target hybridization. After amplifying one DNA oligoprobe of interest, it can be used to create 100 different probes on 100 different sets of microspheres, each with the capability of capturing 100 potential targets (if using a 100-plex array). Similarly, target DNA samples are usually PCR amplified and labeled. Hybridization between the capture probe and the target DNA is achieved by melting and annealing complementary target DNA sequences to their capture probes located on the microspheres. After washing to remove non-specific binding between sequences, only strongly paired probe-targets will remain hybridized. | 1 | Applied and Interdisciplinary Chemistry |
A fluorophore's environment can impact quantum yield, usually resulting from changes in the rates of non-radiative decay. Many fluorophores used to label macromolecules are sensitive to solvent polarity. The class of 8-anilinonaphthalene-1-sulfonic acid (ANS) probe molecules are essentially non-fluorescent when in aqueous solution, but become highly fluorescent in nonpolar solvents or when bound to proteins and membranes. The quantum yield of ANS is ~0.002 in aqueous buffer, but near 0.4 when bound to serum albumin. | 0 | Theoretical and Fundamental Chemistry |
Phytoplankton produces DOC by extracellular release commonly accounting between 5 and 30% of their total primary production, although this varies from species to species. Nonetheless, this release of extracellular DOC is enhanced under high light and low nutrient levels, and thus should increase relatively from eutrophic to oligotrophic areas, probably as a mechanism for dissipating cellular energy. Phytoplankton can also produce DOC by autolysis during physiological stress situations e.g., nutrient limitation. Other studies have demonstrated DOC production in association with meso- and macro-zooplankton feeding on phytoplankton and bacteria. | 1 | Applied and Interdisciplinary Chemistry |
Atmospheric concentrations fluctuate slightly with the seasons, falling during the Northern Hemisphere spring and summer as plants consume the gas and rising during northern autumn and winter as plants go dormant or die and decay. The level drops by about 6 or 7 ppm (about 50 Gt) from May to September during the Northern Hemisphere's growing season, and then goes up by about 8 or 9 ppm. The Northern Hemisphere dominates the annual cycle of concentration because it has much greater land area and plant biomass than the Southern Hemisphere. Concentrations reach a peak in May as the Northern Hemisphere spring greenup begins, and decline to a minimum in October, near the end of the growing season.
Concentrations also vary on a regional basis, most strongly near the ground with much smaller variations aloft. In urban areas concentrations are generally higher and indoors they can reach 10 times background levels. | 1 | Applied and Interdisciplinary Chemistry |
Because of the greater electronegativity of oxygen than nitrogen, the carbonyl (C=O) is a stronger dipole than the N–C dipole. The presence of a C=O dipole and, to a lesser extent a N–C dipole, allows amides to act as H-bond acceptors. In primary and secondary amides, the presence of N–H dipoles allows amides to function as H-bond donors as well. Thus amides can participate in hydrogen bonding with water and other protic solvents; the oxygen atom can accept hydrogen bonds from water and the N–H hydrogen atoms can donate H-bonds. As a result of interactions such as these, the water solubility of amides is greater than that of corresponding hydrocarbons. These hydrogen bonds also have an important role in the secondary structure of proteins.
The solubilities of amides and esters are roughly comparable. Typically amides are less soluble than comparable amines and carboxylic acids since these compounds can both donate and accept hydrogen bonds. Tertiary amides, with the important exception of N,N-dimethylformamide, exhibit low solubility in water. | 0 | Theoretical and Fundamental Chemistry |
At the most simple level, the Olszewski tube is a pipe that spans from the bottom, hypolimnetic layer of the lake to the outlet. The outlet part of the pipe is installed under lake level in order for the device to act as a siphon. Once warm water flows in the lake at the surface, it forces the cold anoxic water of the hypolimnetic layer through and up the tube. This oxygen-poor water is then brought to the top of the lake where the eutrophication occurs. This eventually helps the lake as a whole because the bottom of the lake will have more dissolved oxygen and the top of the lake will have less eutrophication. | 1 | Applied and Interdisciplinary Chemistry |
James Robert Durrant is a British photochemist. He is a professor of photochemistry at Imperial College London and Sêr Cymru Solar Professor at Swansea University. He serves as director of the centre for plastic electronics (CPE). | 0 | Theoretical and Fundamental Chemistry |
Sulfur has 24 known isotopes, 4 of which are stable (meaning that they do not undergo radioactive decay). S, the common isotope of sulfur, makes up 95.0% of the natural sulfur on Earth. In the atomic symbol of S, the number 32 refers to the mass of each sulfur atom in daltons, the result of the 16 protons and 16 neutrons of 1 dalton each that make up the sulfur nucleus. The three rare stable isotopes of sulfur are S (4.2% of natural sulfur), S (0.75%), and S (0.015%). These isotopes differ from S in the number of neutrons in each atom, but not the number of protons or electrons; as a result, each isotope has a slightly different mass, but has nearly identical chemical properties. | 0 | Theoretical and Fundamental Chemistry |
An akamptisomer is a type of conformational isomer characterized by a hindered inversion of a bond angle. It was first discovered in 2018 in a series of bridged porphyrin molecules. | 0 | Theoretical and Fundamental Chemistry |
* azotic air
* azote – means lifeless, or a-zote for "not life", generally regarded as the solid constituent whereas azotic gas was the gaseous form.
* phlogisticated air
*atmospherical memphitic gas
* mephitis
*nitrogene
* base of mephitis
*stickstoffgas | 1 | Applied and Interdisciplinary Chemistry |
Despite its beneficial properties, NiAl generally suffers from two factors: very high brittleness at low temperatures (Al-based alloys these issues are generally addressed via the integration of other elements. Attempted elements can be broken into three groups depending on their influence of microstructure:
* Elements that form ternary intermetallic phases such as Ti and Hf
* Pseudobinary eutectic forming elements such as Cr
* Elements with high solubility in NiAl such as Fe, Co and Cu
Some of the more successful elements have been shown to be Fe, Co and Cr which drastically increase room temperature ductility as well as hot workability. This increase is due to the formation of γ phase which modifies the β phase grains. Alloying with Fe, Ga and Mo has also been shown to drastically improve room temperature ductility as well. Most recently, refracturing metals such as Cr, W and Mo have been added and resulted in not only increases in room temperature ductility but also increases in strength and fracture toughness at high temperatures. This is due to the formation of unique microstructures such as the eutectic alloy NiAlMo and α-Cr inclusions that contribute to solid solution hardening. It is even being shown that these complex alloys (NiAlCrMo) have the potential to be fabricated via additive manufacturing processes such as selective laser manufacturing, vastly increasing the potential applications for these alloys. | 1 | Applied and Interdisciplinary Chemistry |
Numerous hybrid organic–inorganic materials that contain POM cores,
Illustrative of the diverse structures of POM is the ion , which has face-shared octahedra with Mo atoms at the vertices of an icosahedron). | 0 | Theoretical and Fundamental Chemistry |
In animals and humans, after ingestion, natural phenols become part of the xenobiotic metabolism. In subsequent phase II reactions, these activated metabolites are conjugated with charged species such as glutathione, sulfate, glycine or glucuronic acid. These reactions are catalysed by a large group of broad-specificity transferases. UGT1A6 is a human gene encoding a phenol UDP glucuronosyltransferase active on simple phenols. The enzyme encoded by the gene UGT1A8 has glucuronidase activity with many substrates including coumarins, anthraquinones and flavones. | 0 | Theoretical and Fundamental Chemistry |
When the depositing particles attract each other, they will deposit and aggregate at the same time. This situation will result in a porous layer made of particle aggregates at the surface, and is referred to as ripening. The porosity of this layer will depend whether the particle aggregation process is fast or slow. Slow aggregation will lead to a more compact layer, while fast aggregation to a more porous one. The structure of the layer will resemble the structure of the aggregates formed in the later stages of the aggregation process. | 0 | Theoretical and Fundamental Chemistry |
PET imaging has been used for imaging muscles and bones. FDG is the most commonly used tracer for imaging muscles, and NaF-F18 is the most widely used tracer for imaging bones. | 1 | Applied and Interdisciplinary Chemistry |
Diversity-generating retroelements (DGRs) are a family of retroelements that were first found in Bordetella phage (BPP-1), and since been found in bacteria (e.g.Treponema denticola and Legionella pneumophila), Archaea, Archaean viruses (e.g. ANMV-1), temperate phages (e.g. Hankyphage and CrAss-like phage), and lytic phages. DGRs benefit their host by mutating particular regions of specific target proteins, for instance, phage tail fiber in BPP-1, lipoprotein in legionella pneumophila ( the pathogen behind Legionnaires disease), and TvpA in Treponema denticola (oral-associated periopathogen). An error-prone reverse transcriptase is responsible for generating these hypervariable regions in target proteins (Mutagenic retrohoming). In mutagenic retrohoming, a mutagenized cDNA (containing substantial A to N mutations) is reverse transcribed from a template region (TR), and is replaced with a segment similar to the template region called variable region (VR). Accessory variability determinant (Avd) protein is another component of DGRs, and its complex formation with the error-prone RT is of importance to mutagenic rehoming.
DGRs are beneficial to the evolution and survival of their host. A large fraction of Faecalibacterium prausnitzii phages contain DGRs that are believed to have a role in phage adaptability to the digestive system, as patients with inflammatory bowel disease (IBD), have more phages, but less F.prausnitzii in their stool samples compared to healthy individuals, suggesting that these phages activate during the illness, and that they may trigger F.prausnitzii depletion. Several tools have been implemented to identify DGRs, such as DiGReF, DGRscan, MetaCSST, and myDGR | 1 | Applied and Interdisciplinary Chemistry |
The mechanism of nucleophilic substitution by lower-order organocuprates depends in a profound way on the structure of the substrate, organocuprate, and reaction conditions. Early evidence suggested that a direct S2 displacement was occurring; however more recent results suggest that invertive oxidative addition of copper(I) into the carbon-leaving group bond takes place, generating a copper(III) intermediate which then undergoes reductive elimination to generate the coupled product. Both of these mechanisms predict inversion at the electrophilic carbon, which is observed in a number of cases. On the other hand, experiments with radical traps and the observation of racemization during substitution suggest a radical mechanism. | 0 | Theoretical and Fundamental Chemistry |
CDPs forests program has over 290 signatory investors in its network, which collectively represent about US$19 trillion in combined assets. CDP collects information about the four agricultural commodities responsible for most deforestation: timber, palm oil, cattle and soy. CDPs forests program was first set up by the UK Government's Department for International Development via the Global Canopy Programme and the JMG Foundation. | 1 | Applied and Interdisciplinary Chemistry |
The Z-factor is a measure of statistical effect size. It has been proposed for use in high-throughput screening (HTS), where it is also known as Z-prime, to judge whether the response in a particular assay is large enough to warrant further attention. | 1 | Applied and Interdisciplinary Chemistry |
Capillary pressure formulas are derived from the pressure relationship between two fluid phases in a capillary tube in equilibrium, which is that force up = force down. These forces are described as:
These forces can be described by the interfacial tension and contact angle of the fluids, and the radius of the capillary tube. An interesting phenomena, capillary rise of water (as pictured to the right) provides a good example of how these properties come together to drive flow through a capillary tube and how these properties are measured in a system. There are two general equations that describe the force up and force down relationship of two fluids in equilibrium.
The Young–Laplace equation is the force up description of capillary pressure, and the most commonly used variation of the capillary pressure equation:
where:
: is the interfacial tension
: is the effective radius of the interface
: is the wetting angle of the liquid on the surface of the capillary
The force down formula for capillary pressure is seen as:
where:
: is the height of the capillary rise
: is the density gradient of the wetting phase
: is the density gradient of the non-wetting phase | 1 | Applied and Interdisciplinary Chemistry |
mA is not the only RNA modification that can be found in viral RNAs. For instance, N,2-O-dimethyladenosine (mA) can be found in influenza and herpes simplex virus type 1, even though the effect this mark has on the life cycle of these viruses remains unknown. NAT10 mediated acetylation of cytidines on HIV-1 RNA was recently reported. Another modification commonly found in coronaviruses, flaviviruses and poxviruses (all of them are cytoplasmic viruses) is the 2-O-methylation of ribose moieties. The addition of this mark is catalyzed by a viral methyltransferase. 2-O-methylation binds to and inhibits Toll-like receptor 7 (TLR-7), which is involved in activating the production of inflammatory cytokines. Moreover, this modification enables viral RNAs to evade the antiviral actions of the IFIT proteins, a family of interferon-induced proteins that limit viral replication. | 1 | Applied and Interdisciplinary Chemistry |
Lipidology is the scientific study of lipids. Lipids are a group of biological macromolecules that have a multitude of functions in the body. Clinical studies on lipid metabolism in the body have led to developments in therapeutic lipidology for disorders such as cardiovascular disease. | 1 | Applied and Interdisciplinary Chemistry |
The IPF's research program is jointly set up and implemented by researchers of the different IPF institutes. They address six strategic topics:
# Basic concepts of soft matter
# Bio-inspired materials
# Functional materials and system integration
# Process controlled structural materials
# Data science-based material research
# Sustainability and environment protection | 1 | Applied and Interdisciplinary Chemistry |
Reaction centers are multi-protein complexes found within the thylakoid membrane.
At the heart of a photosystem lies the reaction center, which is an enzyme that uses light to reduce and oxidize molecules (give off and take up electrons). This reaction center is surrounded by light-harvesting complexes that enhance the absorption of light.
In addition, surrounding the reaction center are pigments which will absorb light. The pigments which absorb light at the highest energy level are found furthest from the reaction center. On the other hand, the pigments with the lowest energy level are more closely associated with the reaction center. Energy will be efficiently transferred from the outer part of the antenna complex to the inner part. This funneling of energy is performed via resonance transfer, which occurs when energy from an excited molecule is transferred to a molecule in the ground state. This ground state molecule will be excited, and the process will continue between molecules all the way to the reaction center. At the reaction center, the electrons on the special chlorophyll molecule will be excited and ultimately transferred away by electron carriers. (If the electrons were not transferred away after excitation to a high energy state, they would lose energy by fluorescence back to the ground state, which would not allow plants to drive photosynthesis.) The reaction center will drive photosynthesis by taking light and turning it into chemical energy that can then be used by the chloroplast.
Two families of reaction centers in photosystems can be distinguished: type I reaction centers (such as photosystem I (P700) in chloroplasts and in green-sulfur bacteria) and type II reaction centers (such as photosystem II (P680) in chloroplasts and in non-sulfur purple bacteria). The two photosystems originated from a common ancestor, but have since diversified.
Each of the photosystem can be identified by the wavelength of light to which it is most reactive (700 nanometers for PSI and 680 nanometers for PSII in chloroplasts), the amount and type of light-harvesting complex present, and the type of terminal electron acceptor used.
Type I photosystems use ferredoxin-like iron-sulfur cluster proteins as terminal electron acceptors, while type II photosystems ultimately shuttle electrons to a quinone terminal electron acceptor. Both reaction center types are present in chloroplasts and cyanobacteria, and work together to form a unique photosynthetic chain able to extract electrons from water, creating oxygen as a byproduct. | 0 | Theoretical and Fundamental Chemistry |
Even though the surface tension can be greatly reduced by pulmonary surfactant, this effect will depend on the surfactants concentration on the interface. The interface concentration has a saturation limit, which depends on temperature and mixture composition. Because during ventilation there is a variation of the lung surface area, the surfactants interface concentration is not usually at the level of saturation. The surface increases during inspiration, which consequently opens space for new surfactant molecules to be recruited to the interface. Meanwhile, during expiration the surface area decreases at a rate which is always in excess of the rate at which the surfactant molecules are driven from the interface into the water film. Thus, the surfactant density at the air water interface remains high and is relatively preserved throughout expiration, decreasing the surface tension even further. This also explains why the compliance is greater during expiration than during inspiration.
SP molecules contribute to increasing the surfactant interface adsorption kinetics, when the concentration is below the saturation level. They also make weak bonds with the surfactant molecules at the interface and hold them longer there when the interface is compressed. Therefore, during ventilation, surface tension is usually lower than at equilibrium. Therefore, the surface tension varies according to the volume of air in the lungs, which protects them from atelectasis at low volumes and tissue damage at high volume levels. | 0 | Theoretical and Fundamental Chemistry |
Committed dose equivalent and Committed effective dose equivalent are dose quantities used in the United States system of radiological protection for irradiation due to an internal source. | 0 | Theoretical and Fundamental Chemistry |
One of the most prolific of these modern biochemists was Hans Krebs who made huge contributions to the study of metabolism. Krebs was a student of extremely important Otto Warburg, and wrote a biography of Warburg by that title in which he presents Warburg as being educated to do for biological chemistry what Fischer did for organic chemistry. Which he did. Krebs discovered the urea cycle and later, working with Hans Kornberg, the citric acid cycle and the glyoxylate cycle. These discoveries led to Krebs being awarded the Nobel Prize in physiology in 1953, which was shared with the German biochemist Fritz Albert Lipmann who also codiscovered the essential cofactor coenzyme A. | 1 | Applied and Interdisciplinary Chemistry |
In contrast, renewable energy sources, particularly wind and solar power, have seen substantial growth. This is not only due to the environmental benefits they offer but also because of their increasingly competitive costs. The technological advancements in renewable energy, alongside supportive government policies, have made these sources more accessible and affordable. | 1 | Applied and Interdisciplinary Chemistry |
Seven autotrophic carbon fixation pathways are known. The Calvin cycle fixes carbon in the chloroplasts of plants and algae, and in the cyanobacteria. It also fixes carbon in the anoxygenic photosynthesis in one type of Pseudomonadota called purple bacteria, and in some non-phototrophic Pseudomonadota.
Of the five other autotrophic pathways, two are known only in bacteria (the reductive citric acid cycle and the 3-hydroxypropionate cycle), two only in archaea (two variants of the 3-hydroxypropionate cycle), and one in both bacteria and archaea (the reductive acetyl CoA pathway). | 0 | Theoretical and Fundamental Chemistry |
Although Agricola died in 1555, the publication was delayed until the completion of the extensive and detailed woodcuts one year after his death.
A German translation was published in 1557 and a second Latin edition appeared in 1561. A version in Spanish, though not a mere translation, was produced by Bernardo Pérez de Vargas in 1569. This was translated into French as Traité singulier de metallique in 1743.
In 1912, the first English translation of De Re Metallica was privately published in London by subscription. The translators and editors were Herbert Hoover, a mining engineer (and later President of the United States), and his wife, Lou Henry Hoover, a geologist and Latinist. The translation is notable not only for its clarity of language, but for the extensive footnotes, which detail the classical references to mining and metals, such as the Naturalis Historia of Pliny the Elder, the history of mining law in England, France, and the German states; safety in mines, including historical safety; and known minerals at the time that Agricola wrote De Re Metallica. No expense was spared for this edition: in its typography, fine paper and binding, quality of reproduced images, and vellum covers, the publisher attempted to match the extraordinarily high standards of the sixteenth-century original. As a consequence, copies of this 1912 edition are now both rare and valuable. Fortunately, the translation has been reprinted by Dover Books.
Subsequent translations into other languages, including German, owe much to the Hoover translations, as their footnotes detail their difficulties with Agricola's invention of several hundred Latin expressions to cover Medieval German mining and milling terms unknown to classical Latin. | 1 | Applied and Interdisciplinary Chemistry |
Upon the identification of the early targets of arginylation by ATE1 (in vitro and in vivo), a pattern emerged. This pattern showed that ATE1 displayed a high affinity for proteins and peptides containing the acidic amino acids asparagine or glutamine which were exposed on the N-terminal side of the protein or peptide. Further studies aided by high precision mass spectrometry have revealed hundreds of proteins from different cells and tissues which have been arginylated. Several of these proteins also displayed arginylation at their N-chain termini, but contained residues other than asparagine or glutamine. As such, arginylation studies are still in the introductory stages and further research into the specificity of arginylation must be performed.
However, the assumption that arginylation only occurs at the N-terminus severely limited the amount of proteins which were likely to be arginylated. This is due to the fact that, if the preference of arginylation to occur only at the N-terminus assumption was true, then arginylation would never be able to happen on intact proteins due to protein sequences beginning with methionine at the N-terminus and not the preferred asparagine or glutamine. This assumption was soon proved false when a protein was discovered with an arginylated residue in the middle of its sequence. | 1 | Applied and Interdisciplinary Chemistry |
Product packaging is an important aspect of maintaining the quality of consumer goods. Modern day packaging is split into 2 categories; active packaging and smart packaging. Thermochromic ink has found use in smart packaging, which is the aspect of packaging that deals with monitoring the condition of the products. Since most of the consumer goods are affected by changes in temperature, using thermochromic ink as an indicator of those temperature changes allows consumers to recognize when the quality of a product has changed. It can also be used to tell consumers the right temperatures to consume the product. | 0 | Theoretical and Fundamental Chemistry |
Plastic pipe systems fulfil a variety of service requirements. Product standards for plastics pipe systems are prepared within the CEN/TC155 standards committee. These requirements are described in a set of European Product Standards for each application alongside their specific characteristics, for example:
*Conveyance of drinking water: Hygienic requirements
*Conveyance of gas: Highest Safety requirements
*Plastic pipes for radiant heating and floor heating: Temperature resistance over decades
*Sewer applications: High chemical resistance
Plastic pipes are capable of fulfilling the specific requirement for each application. They do so over a long lifetime and with reliability and safety. The key success factor is achieved by maintaining consistently high quality levels. For plastic pipe products, these levels are defined by the different standards. Two aspects are fundamentally important for the performance of plastic pipes: flexibility and long lifetime. | 1 | Applied and Interdisciplinary Chemistry |
Leprecan, a proteoglycan, has demonstrated prolyl hydroxylase activity; prolyl hydroxylases hydroxylate proline residues. Prolyl 3-hydroxylase 1, P3H1, forms a larger complex with CRTAP and cyclophilin B, CyPB, in the endoplasimic reticulum. The complex hydroxylates a single proline residue, Pro986, on collagen chains. Recessive forms of Osteogenesis Imperfecta are partly caused by a mutation in the LEPRE1 gene. The mutation in the gene encodes prolyl 3-hydroxylase 1. The malfunctioning prolyl 3-hydroxylase in leprecan leads to inappropriate collagen folding. This is due to the instability caused by the absence of hydroxyproline. Hydroxyproline is the product of hydroxylating a proline residue. | 1 | Applied and Interdisciplinary Chemistry |
Several groups of animals have formed symbiotic relationships with photosynthetic algae. These are most common in corals, sponges, and sea anemones. Scientists presume that this is due to the particularly simple body plans and large surface areas of these animals compared to their volumes. In addition, a few marine mollusks, such as Elysia viridis and Elysia chlorotica, also maintain a symbiotic relationship with chloroplasts they capture from the algae in their diet and then store in their bodies (see Kleptoplasty). This allows the mollusks to survive solely by photosynthesis for several months at a time. Some of the genes from the plant cell nucleus have even been transferred to the slugs, so that the chloroplasts can be supplied with proteins they need to survive.
An even closer form of symbiosis may explain the origin of chloroplasts. Chloroplasts have many similarities with photosynthetic bacteria, including a circular chromosome, prokaryotic-type ribosome, and similar proteins in the photosynthetic reaction center. The endosymbiotic theory suggests that photosynthetic bacteria were acquired (by endocytosis) by early eukaryotic cells to form the first plant cells. Therefore, chloroplasts may be photosynthetic bacteria that adapted to life inside plant cells. Like mitochondria, chloroplasts possess their own DNA, separate from the nuclear DNA of their plant host cells and the genes in this chloroplast DNA resemble those found in cyanobacteria. DNA in chloroplasts codes for redox proteins such as those found in the photosynthetic reaction centers. The CoRR Hypothesis proposes that this co-location of genes with their gene products is required for redox regulation of gene expression, and accounts for the persistence of DNA in bioenergetic organelles. | 0 | Theoretical and Fundamental Chemistry |
Seasoning is the process of coating the surface of cookware with fat which is heated in order to produce a corrosion resistant layer of polymerized fat. It is required for raw cast-iron cookware and carbon steel, which otherwise rust rapidly in use, but is also used for many other types of cookware. An advantage of seasoning is that it helps prevent food sticking.
Some cast-iron and carbon steel cookware is pre-seasoned by manufacturers to protect the pan from oxidation (rust), but will need to be further seasoned by the end-users for the cookware to become ready for best nonstick cooking results. To form a strong seasoning, the raw iron item is thoroughly cleaned, coated in a very thin layer of unsaturated fat or oil, and then heated until the bioplastic layer forms, and left to completely cool. Multiple layers are required for the best long-term results.
Stainless steel and aluminium cookware do not require protection from corrosion, but seasoning reduces sticking, and can help with browning as the seasoning coating has high thermal emissivity. Other cookware surfaces are generally not seasoned.
A seasoned surface is hydrophobic and highly attractive to oils and fats used for cooking. These form a layer that prevents foods, which typically contain water, from touching and cooking onto the hydrophilic metallic cooking surface underneath. These properties are useful when frying, roasting and baking. | 0 | Theoretical and Fundamental Chemistry |
Taste is a form of chemoreception that takes place in the specialised taste receptors, contained in structures called taste buds in the mouth. Taste buds are mainly on the upper surface (dorsum) of the tongue. The function of taste perception is vital to help prevent harmful or rotten foods from being consumed. There are also taste buds on the epiglottis and upper part of the esophagus. The taste buds are innervated by a branch of the facial nerve the chorda tympani, and the glossopharyngeal nerve. Taste messages are sent via these cranial nerves to the brain. The brain can distinguish between the chemical qualities of the food. The five basic tastes are referred to as those of saltiness, sourness, bitterness, sweetness, and umami. The detection of saltiness and sourness enables the control of salt and acid balance. The detection of bitterness warns of poisons—many of a plant's defences are of poisonous compounds that are bitter. Sweetness guides to those foods that will supply energy; the initial breakdown of the energy-giving carbohydrates by salivary amylase creates the taste of sweetness since simple sugars are the first result. The taste of umami is thought to signal protein-rich food. Sour tastes are acidic which is often found in bad food. The brain has to decide very quickly whether the food should be eaten or not. It was the findings in 1991, describing the first olfactory receptors that helped to prompt the research into taste. The olfactory receptors are located on cell surfaces in the nose which bind to chemicals enabling the detection of smells. It is assumed that signals from taste receptors work together with those from the nose, to form an idea of complex food flavours. | 1 | Applied and Interdisciplinary Chemistry |
Currently, the majority of circulating tumour DNA (ctDNA) fragmentomic techniques lack the ability to achieve gene-level resolution and are effective mainly in inferring expression at elevated ctDNA levels. Consequently, they are primarily applicable to patients with notably advanced tumour burdens typically seen in late-stage cancer.
To address this limitation, EPIC-seq employs hybrid capture-based targeted deep sequencing of regions flanking transcription start sites (TSS) in cfDNA. This approach allows for the acquisition of ctDNA fragmentation features crucial for predicting gene expressions, such as Promoter Fragmentation Entropy (PFE) and Nucleosome Depleted Region (NDR). These key fragmentomic features possess the capability to capture associations at the gene level with expression levels throughout the genome, enabling the construction of a predictive model for transcriptional output. This would allows for the high-resolution monitoring of cfDNA fragmentation and gene-level analysis. | 1 | Applied and Interdisciplinary Chemistry |
After an intake of 1.5 mg levonorgestrel in clinical trials, very common side effects (reported by 10% or more) included: hives, dizziness, hair loss, headache, nausea, abdominal pain, uterine pain, delayed menstruation, heavy menstruation, uterine bleeding, and fatigue; common side effects (reported by 1% to 10%) included diarrhea, vomiting, and painful menstruation; these side effects usually disappeared within 48 hours. However, the long term side effects common with oral contraceptives such as arterial disease are lower with levonorgestrel than in combination pills.
Levonorgestrel as a contraceptive intrauterine device is associated with a higher risk of breast cancer than with non-use. | 0 | Theoretical and Fundamental Chemistry |
T790M, also known as Thr790Met, is a gatekeeper mutation of the epidermal growth factor receptor (EGFR). The mutation substitutes a threonine (T) with a methionine (M) at position 790 of exon 20, affecting the ATP binding pocket of the EGFR kinase domain. Threonine is a small polar amino acid; methionine is a larger nonpolar amino acid. Rather than directly blocking inhibitor binding to the active site, T790M increases the affinity for ATP so that the inhibitors are outcompeted; irreversible covalent inhibitors such as osimertinib can overcome this resistance. | 1 | Applied and Interdisciplinary Chemistry |
The discovery of mTOR was made in 1994 while investigating the mechanism of action of its inhibitor, rapamycin. Rapamycin was first discovered in 1975 in a soil sample from Easter Island of South Pacific, also known as Rapa Nui, from where its name is derived. Rapamycin is a macrolide, produced by the microorganism Streptomyces hygroscopicus and showed antifungal properties. Shortly after its discovery, immunosuppressive properties were detected, which later led to the establishment of rapamycin as an immunosuppressant. In the 1980s, rapamycin was also found to have anticancer activity although the exact mechanism of action remained unknown until many years later.
In the 1990s there was a dramatic change in this field due to studies on the mechanism of action of rapamycin and the identification of the drug target. It was found that rapamycin inhibited cellular proliferation and cell cycle progression. Research on mTOR inhibition has been a growing branch in science and has promising results. | 1 | Applied and Interdisciplinary Chemistry |
Everhardus Ariëns 1963 was honored at the second International Congress of Pharmacology in Prague with the Purkinje Medal. In 1970 he became member of the Royal Netherlands Academy of Arts and Sciences. He also received the Dr. Saal van Zwanenberg Award (1972), the Medal of the Norwegian Poulsson Pharmacological Society (1973), the Scheele Award (1974), the Schmiedeberg Medal (1980) and the Smissman Award of the American Chemical Society (1985).
Everhardus Ariëns was awarded honorary doctorates from universities Universidade Luterana do Brasil, University of Kiel, University of Paris-Sud and Università degli Studi di Camerino. Another honorary doctorate was awarded in March 2002 at the Ohio State University. | 0 | Theoretical and Fundamental Chemistry |
The concept underlying the SCGE assay is that undamaged DNA retains a highly organized association with matrix proteins in the nucleus. When damaged, this organization is disrupted. The individual strands of DNA lose their compact structure and relax, expanding out of the cavity into the agarose. When the electric field is applied the DNA, which has an overall negative charge, is drawn towards the positively charged anode. Undamaged DNA strands are too large and do not leave the cavity, whereas the smaller the fragments, the farther they are free to move in a given period of time. Therefore, the amount of DNA that leaves the cavity is a measure of the amount of DNA damage in the cell.
The image analysis measures the overall intensity of the fluorescence for the whole nucleoid and the fluorescence of the migrated DNA and compares the two signals. The stronger the signal from the migrated DNA the more damage there is present. The overall structure resembles a comet (hence "comet assay") with a circular head corresponding to the undamaged DNA that remains in the cavity and a tail of damaged DNA. The brighter and longer the tail, the higher the level of damage.
The comet assay is a versatile technique for detecting damage and with adjustments to the protocol can be used to quantify the presence of a wide variety of DNA altering lesions (damage). The damage usually detected are single strand breaks and double strand breaks. It is sometimes stated that alkaline conditions and complete denaturating of the DNA is necessary to detect single strand breaks. However this is not true, both single- and double strand breaks are also detected in neutral conditions. In alkaline conditions, however, additional DNA structures are detected as DNA damage: AP sites (abasic sites missing either a pyrimidine or purine nucleotide) and sites where excision repair is taking place.
The comet assay is an extremely sensitive DNA damage assay. This sensitivity needs to be handled carefully as it is also vulnerable to physical changes which can affect the reproducibility of results. Essentially, anything that can cause DNA damage or denaturation except the factor(s) being researched is to be avoided. The most common form of the assay is the alkaline version although there is as yet no definitive alkaline assay protocol. Due to its simple and inexpensive setup, it can be used in conditions where more complex assays are not available. | 1 | Applied and Interdisciplinary Chemistry |
A mitogen-activated protein kinase (MAPK or MAP kinase) is a type of protein kinase that is specific to the amino acids serine and threonine (i.e., a serine/threonine-specific protein kinase). MAPKs are involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflammatory cytokines. They regulate cell functions including proliferation, gene expression, differentiation, mitosis, cell survival, and apoptosis.
MAP kinases are found in eukaryotes only, but they are fairly diverse and encountered in all animals, fungi and plants, and even in an array of unicellular eukaryotes.
MAPKs belong to the CMGC (CDK/MAPK/GSK3/CLK) kinase group. The closest relatives of MAPKs are the cyclin-dependent kinases (CDKs). | 1 | Applied and Interdisciplinary Chemistry |
Fast Sulphon Black F is a complexometric indicator used with EDTA, almost exclusively used in copper complexation determination. | 0 | Theoretical and Fundamental Chemistry |
Most presynaptic terminals release small numbers of neurotransmitter containing vesicles even when action potentials are not present. This is stochastic and the probability of release (Pr) can be modified by numerous factors including the presence and speed of an action potential. These vesicles are released at synaptic active zones, areas of the axon terminal that have all of the machinery and conditions necessary to specialize in vesicle fusion with the plasma membrane. Until relatively recently, the prevailing hypothesis was that only one vesicle at a time is released from these active zones. However, research over the past several decades has added support for an additional mechanism of neurotransmitter vesicle release. | 1 | Applied and Interdisciplinary Chemistry |
Americium often enters landfills from discarded smoke detectors. The rules associated with the disposal of smoke detectors are very relaxed in most municipalities. For instance, in the UK it is permissible to dispose of an americium containing smoke detector by placing it in the dustbin with normal household rubbish, but each dustbin worth of rubbish is limited to only containing one smoke detector. The manufacture of products containing americium (such as smoke detectors) as well as nuclear reactors and explosions may also release the americium into the environment.
In 1999, a truck transporting 900 smoke detectors in France had been reported to have caught fire; it is claimed that this led to a release of americium into the environment. In the U.S., the "Radioactive Boy Scout" David Hahn was able to buy thousands of smoke detectors at remainder prices and concentrate the americium from them.
There have been cases of humans being exposed to americium. The worst case was that of Harold McCluskey, who was exposed to an extremely high dose of americium-241 after an accident involving a glove box. He was subsequently treated with chelation therapy. It is likely that the medical care which he was given saved his life; despite similar biodistribution and toxicity to plutonium, the two radioactive elements have different solution-state chemistries. Americium is stable in the +3 oxidation state, while the +4 oxidation state of plutonium can form in the human body.
The most common isotope americium-241 decays (half-life 432 years) to neptunium-237 which has a much longer half-life, so in the long term, the issues discussed above for neptunium apply.
Americium released into the environment tends to remain in soil and water at relatively shallow depths and may be taken up by animals and plants during growth; shellfish such as shrimp take up americium-241 in their shells, and parts of grain plants can become contaminated with exposure. In a 2021 paper, J.D. Chaplin et al. reported advances in the Diffusive gradients in thin films technique, which have provided a method to measure labile bioavailable Americium in soils, as well as in freshwater and seawater. | 0 | Theoretical and Fundamental Chemistry |
Prime editing involves three major components:
* A prime editing guide RNA (pegRNA), capable of (i) identifying the target nucleotide sequence to be edited, and (ii) encoding new genetic information that replaces the targeted sequence. The pegRNA consists of an extended single guide RNA (sgRNA) containing a primer binding site (PBS) and a reverse transcriptase (RT) template sequence. During genome editing, the primer binding site allows the 3’ end of the nicked DNA strand to hybridize to the pegRNA, while the RT template serves as a template for the synthesis of edited genetic information.
* A fusion protein consisting of a Cas9 H840A nickase fused to a Moloney Murine Leukemia Virus (M-MLV) reverse transcriptase.
**Cas9 H840A nickase: the Cas9 enzyme contains two nuclease domains that can cleave DNA sequences, a RuvC domain that cleaves the non-target strand and a HNH domain that cleaves the target strand. The introduction of a H840A substitution in Cas9, through which the 840th amino acid histidine is replaced by an alanine, inactivates the HNH domain. With only the RuvC functioning domain, the catalytically impaired Cas9 introduces a single strand nick, hence the name nickase.
**M-MLV reverse transcriptase: an enzyme that synthesizes DNA from a single-stranded RNA template.
* A single guide RNA (sgRNA) that directs the Cas9 H840A nickase portion of the fusion protein to nick the non-edited DNA strand. | 1 | Applied and Interdisciplinary Chemistry |
Several theoretical models exist to predict the order of duplication and specialisation events, but the actual process is more intertwined and fuzzy (§ Reconstructed enzymes below). On one hand, gene amplification results in an increase in enzyme concentration, and potentially freedom from a restrictive regulation, therefore increasing the reaction rate (v) of the promiscuous activity of the enzyme making its effects more pronounced physiologically ("gene dosage effect"). On the other, enzymes may evolve an increased secondary activity with little loss to the primary activity ("robustness") with little adaptive conflict (§ Robustness and plasticity below). | 1 | Applied and Interdisciplinary Chemistry |
Stringers are filaments of slag left in wrought iron after the production process. In their correct proportions their presence is beneficial, as they help to control the ductility of the finished product, but when the proportion of slag is too high, or when the filaments run at right angles to the direction of tension, they can cause weakness. | 1 | Applied and Interdisciplinary Chemistry |
Some atoms, notably uranium-238, do not usually undergo fission when struck by slow neutrons, but do split when struck with neutrons of high enough energy. The fast neutrons produced in a hydrogen bomb by fusion of deuterium and tritium have even higher energy than the fast neutrons produced in a nuclear reactor. This makes it possible to increase the yield of any given fusion weapon by the simple expedient of adding layers of cheap natural (or even depleted) uranium. Fast fission of uranium-238 provides a large part of the explosive yield, and fallout, in many designs of hydrogen bomb. | 0 | Theoretical and Fundamental Chemistry |
* 2003 - Rfam: an RNA family database.
* 2005 - Rfam: annotating non-coding RNAs in complete genomes.
* 2008 - The RNA WikiProject: community annotation of RNA families.
* 2008 - Rfam: updates to the RNA families database.
* 2011 - Rfam: Wikipedia, clans and the “decimal” release.
* 2012 - Rfam 11.0: 10 years of RNA families.
* 2014 - Rfam 12.0: updates to the RNA families database.
* 2017 - Rfam 13.0: shifting to a genome-centric resource for non-coding RNA families.
* 2020 - Rfam 14: expanded coverage of metagenomic, viral and microRNA families. | 1 | Applied and Interdisciplinary Chemistry |
The specific weight, , of a material is defined as the product of its density, , and the standard gravity, :
The density of the material is defined as mass per unit volume, typically measured in kg/m. The standard gravity is acceleration due to gravity, usually given in m/s, and on Earth usually taken as .
Unlike density, specific weight is not a fixed property of a material. It depends on the value of the gravitational acceleration, which varies with location. Pressure may also affect values, depending upon the bulk modulus of the material, but generally, at moderate pressures, has a less significant effect than the other factors. | 0 | Theoretical and Fundamental Chemistry |
A common sulfonyl hydrazide is p-toluenesulfonyl hydrazide, a white air-stable solid. They are also widely used as organic reagents.
Toluenesulfonyl hydrazide is used to generate toluenesulfonyl hydrazones. When derived from ketones, these hydrazones participate in the Shapiro reaction and the Eschenmoser–Tanabe fragmentation.
2,4,6-Triisopropylbenzenesulfonylhydrazide is a useful source of diimide. | 0 | Theoretical and Fundamental Chemistry |
Nucleic acid secondary structure is generally divided into helices (contiguous base pairs), and various kinds of loops (unpaired nucleotides surrounded by helices). Frequently these elements, or combinations of them, are further classified into additional categories including, for example, tetraloops, pseudoknots, and stem-loops. Topological approaches can be used to categorize and compare complex structures that arise from combining these elements in various arrangements. | 0 | Theoretical and Fundamental Chemistry |
Taube was born November 30, 1915, in Neudorf, Saskatchewan, as the youngest of four boys. His parents were ethnic Germans from Ukraine who had immigrated to Saskatchewan from Ukraine in 1911. Growing up, his first language was Low German. In the 18th century, Catherine the Great encouraged Central European farmers to settle in Russia. As the rights afforded to these settlers by Catherine were gradually diminished, many of the settlers headed to North America, with Saskatchewan offering good farmland, and other incentives for immigrants. Taube reflected fondly on his experiences growing up in Saskatchewan, noting: "Certainly, there is nothing about my first 21 years in Saskatchewan, taken in the context of those times that I would wish to be changed. The advantages that I enjoyed include: the marvelous experience of growing up on a farm, which taught me an appreciation of nature, and taught me also to discipline myself to get necessary jobs done..."
After completing his graduate studies, Taube became a naturalized citizen of the United States in 1942. Taube married his wife Mary in 1952. They had three children, Karl, Heinrich, and Linda. His stepdaughter Marianna died of cancer in 1998. When he stopped his active research projects in 2001, Taube continued to be available as a reviewer and consultant, but his main goal was "enjoying life". Away from chemistry, Taube had varied interests including gardening and classical music, mainly opera. In 2003 he was one of 22 Nobel laureates who signed the Humanist Manifesto.
Taube died at his home in Palo Alto, California on November 16, 2005, at the age of 89. | 0 | Theoretical and Fundamental Chemistry |
The concentrations of free calcium in the cell can regulate an array of reactions and is important for signal transduction in the cell. Mitochondria can transiently store calcium, a contributing process for the cell's homeostasis of calcium.
Their ability to rapidly take in calcium for later release makes them good "cytosolic buffers" for calcium. The endoplasmic reticulum (ER) is the most significant storage site of calcium, and there is a significant interplay between the mitochondrion and ER with regard to calcium. The calcium is taken up into the matrix by the mitochondrial calcium uniporter on the inner mitochondrial membrane. It is primarily driven by the mitochondrial membrane potential. Release of this calcium back into the cell's interior can occur via a sodium-calcium exchange protein or via "calcium-induced-calcium-release" pathways. This can initiate calcium spikes or calcium waves with large changes in the membrane potential. These can activate a series of second messenger system proteins that can coordinate processes such as neurotransmitter release in nerve cells and release of hormones in endocrine cells.
Ca influx to the mitochondrial matrix has recently been implicated as a mechanism to regulate respiratory bioenergetics by allowing the electrochemical potential across the membrane to transiently "pulse" from ΔΨ-dominated to pH-dominated, facilitating a reduction of oxidative stress. In neurons, concomitant increases in cytosolic and mitochondrial calcium act to synchronize neuronal activity with mitochondrial energy metabolism. Mitochondrial matrix calcium levels can reach the tens of micromolar levels, which is necessary for the activation of isocitrate dehydrogenase, one of the key regulatory enzymes of the Krebs cycle. | 1 | Applied and Interdisciplinary Chemistry |
One current goal of the Joint Center for Structural Genomics (JCSG), a part of the Protein Structure Initiative (PSI) is to solve the structures for all the proteins in Thermotoga maritima, a thermophillic bacterium. T. maritima was selected as a structural genomics target based on its relatively small genome consisting of 1,877 genes and the hypothesis that the proteins expressed by a thermophilic bacterium would be easier to crystallize.
Lesley et al used Escherichia coli to express all the open-reading frames (ORFs) of T. martima. These proteins were then crystallized and structures were determined for successfully crystallized proteins using X-ray crystallography. Among other structures, this structural genomics approach allowed for the determination of the structure of the TM0449 protein, which was found to exhibit a novel fold as it did not share structural homology with any known protein. | 1 | Applied and Interdisciplinary Chemistry |
The ARS is essentially set up to create a fingerprint for different samples by constructive and destructive interferences. Figure 1 is a schematic of the quartz rod ARS which illustrates the path of the sound through the quartz rod. A function generator is the source though any device that is capable of outputting sound in voltage form could be used (i.e. CD player, MP3 player or sound card). White noise is generated and the voltage is converted into a sound wave by a piezoelectric disc coupled to the quartz rod. The sound resonates down the quartz rod which is shown as a blue sinusoidal wave and two key interactions occur. A portion of the energy (red) is introduced into the sample and interacts in a specific manner dependent of the sample and another portion of the energy (blue) continues unaltered through the quartz rod. The two energies will still have the same frequency though they will have changes in their phase and possibly amplitude. The two waves recombine after the sample and constructive or destructive interference occurs depending on the phase shift and amplitude change due to the sample. The altered combined energy is converted to an electrical voltage by another piezoelectric disc at the end of the quartz rod. The voltage is then recorded onto a computer by a sound card. The sample is coupled to the quartz rod at constant pressure which is monitored by a pressure transducer which also acts as the sample holder. Rubber grommets are used to secure the quartz rod to a stable stand minimizing coupling of the rod to the surroundings. Broadband white noise is used to obtain a full spectrum; however, most sound cards only pick up between 20 and 22,050 Hz. The waveform that is sent to the computer is a time-based signal of the interactions of white noise with the sample. Fast Fourier transform (FFT) is performed on the waveform to transform the time-based signal into the more useful frequency spectrum. | 0 | Theoretical and Fundamental Chemistry |
The number of essentially different kinds of constituents in a crystal tends to be small. The repeating units will tend to be identical because each atom in the structure is most stable in a specific environment. There may be two or three types of polyhedra, such as tetrahedra or octahedra, but there will not be many different types. | 0 | Theoretical and Fundamental Chemistry |
The term "environmental toxin" can sometimes explicitly include synthetic contaminants such as industrial pollutants and other artificially made toxic substances. As this contradicts most formal definitions of the term "toxin", it is important to confirm what the researcher means when encountering the term outside of microbiological contexts.
Environmental toxins from food chains that may be dangerous to human health include:
* Paralytic shellfish poisoning (PSP)
* Amnesic shellfish poisoning (ASP)
* Diarrheal shellfish poisoning (DSP)
* Neurotoxic shellfish poisoning (NSP) | 1 | Applied and Interdisciplinary Chemistry |
José Joaquín Barluenga Mur (27 July 1940 – 7 September 2016) was a Spanish chemist known for his research in organometallic chemistry. He was a professor of chemistry at Oviedo University until his retirement in 2014. | 0 | Theoretical and Fundamental Chemistry |
Jean-Claude Duplessy, born in 1942, is a French geochemist. He is Director of Research Emeritus at the CNRS and a member of the French Academy of Sciences. | 0 | Theoretical and Fundamental Chemistry |
Countercurrent distribution (CCD, also spelled "counter current" distribution) is an analytical chemistry technique which was developed by Lyman C. Craig in the 1940s. Countercurrent distribution is a separation process that is founded on the principles of liquid–liquid extraction where a chemical compound is distributed (partitioned) between two immiscible liquid phases (oil and water for example) according to its relative solubility in the two phases. The simplest form of liquid-liquid extraction is the partitioning of a mixture of compounds between two immiscible liquid phases in a separatory funnel. This occurs in five steps: 1) preparation of the separatory funnel with the two phase solvent system, 2) introduction of the compound mixture into the separatory funnel, 3) vigorous shaking of the separatory funnel to mix the two layers and allow for mass transfer of compounds in and out of the phases, 4) The contents of the separatory funnel are allowed to settle back into two distinct phases and 5) the two phases are separated from each other by draining out the bottom phase. If a compound is insoluble in the lower phase it will distribute into the upper phase and stay in the separatory funnel. If a compound is insoluble in the upper phase it will distribute into the lower phase and be removed from the separatory funnel. If the mixture contains one or more compounds that are soluble in the upper phase and one or more compounds that are soluble in the lower phase, then an extraction has occurred. Often, an individual compound is soluble to a certain extent in both phases and the extraction is, therefore, incomplete. The relative solubility of a compound in two phases is known as the partition coefficient.
While one separatory funnel is useful in separating certain compound mixtures with a carefully formulated biphasic solvent system, a series of separatory funnels may be employed to separate compounds that have different partition coefficients. Countercurrent distribution, therefore, is a method of using a series of vessels (separatory funnels) to separate compounds by a sequence of liquid-liquid extraction operations. Contrary to liquid-liquid extraction, in the CCD instruments the upper phase is decanted from the lower phase once the phases have settled. First, a mixture is introduced to vessel 1 (V) charged with both phases and the liquid-liquid extraction process is performed. The upper phase is added to a second vessel (V) which already holds fresh lower phase. Fresh upper phase is added to V. Both vessels are shaken and allowed to settle. upper phase from V is transferred to V at the same time the upper phase from V is transferred to V which already holds fresh lower phase. Fresh upper phase is added to V, all three vessels are shaken and settled and the process continues. Compounds that are more soluble in the upper phase than lower phase faster and farther down the series of vessels (the "train") while those compounds which are more soluble in the lower phase than the upper phase tend to lag behind. A compound insoluble in the upper phase will remain in V while a compound insoluble in the lower phase will stay in the lead vessel. | 0 | Theoretical and Fundamental Chemistry |
More recently many research groups have tried to employ enzymes into DKR synthetic routes. Due to the generally high specificity for substrates, enzymes prove to be vital catalysts for binding to only one stereoisomer in the racemic mixture. In 2007 Bäckvall discovered an enzyme-metal coupled reaction that converts allylic acetates to allylic alcohols with excellent stereospecificity.
In this reaction, a Pd(0) complex is used to interconvert the chirality of the acetate center at a rate fast enough to ensure complete racemization. When this is achieved the CALB enzyme selectively hydrolyzes the (R) substrate because of the low binding affinity for the (S) substrate. This gives almost exclusively the (R) allylic alcohol in 98% ee.
To expand on this chemistry, Bäckvall designed a one-pot, two-reaction system that utilizes the stereochemical outcome of a DKR reaction to undergo a second energetically favorable reaction with high enantioselectivity.
This time a ruthenium complex is used to racemize the allylic alcohol in much the same way as the previous example. The addition of CALB catalyzes the reaction between the (R) isomer and the ester reagent to form a product with a diene and a dienophile. This intermediate can then undergo a tandem Diels-Alder reaction to achieve a decent yield with 97% ee. | 0 | Theoretical and Fundamental Chemistry |
Since metabolism focuses on the breaking down (catabolic processes) of molecules and the building of larger molecules from these particles (anabolic processes), the use of glucose and its involvement in the formation of adenosine triphosphate (ATP) is fundamental to this understanding. The most frequent type of glycolysis found in the body is the type that follows the Embden-Meyerhof-Parnas (EMP) Pathway, which was discovered by Gustav Embden, Otto Meyerhof, and Jakob Karol Parnas. These three men discovered that glycolysis is a strongly determinant process for the efficiency and production of the human body. The significance of the pathway shown in the adjacent image is that by identifying the individual steps in this process doctors and researchers are able to pinpoint sites of metabolic malfunctions such as pyruvate kinase deficiency that can lead to severe anemia. This is most important because cells, and therefore organisms, are not capable of surviving without proper functioning metabolic pathways. | 1 | Applied and Interdisciplinary Chemistry |
The p75 neurotrophin receptor (p75NTR) was first identified in 1973 as the low-affinity nerve growth factor receptor (LNGFR) before discovery that p75NTR bound other neurotrophins equally well as nerve growth factor. p75NTR is a neurotrophic factor receptor. Neurotrophic factor receptors bind Neurotrophins including Nerve growth factor, Neurotrophin-3, Brain-derived neurotrophic factor, and Neurotrophin-4. All neurotrophins bind to p75NTR. This also includes the immature pro-neurotrophin forms. Neurotrophic factor receptors, including p75NTR, are responsible for ensuring a proper density to target ratio of developing neurons, refining broader maps in development into precise connections. p75NTR is involved in pathways that promote neuronal survival and neuronal death. | 1 | Applied and Interdisciplinary Chemistry |
Ziryab started a vogue by changing clothes according to the weather and season. He suggested different clothing for mornings, afternoons and evenings. Henri Terrasse, a French historian of North Africa, commented that legend attributes winter and summer clothing styles and "the luxurious dress of the Orient" found in Morocco today to Ziryab, but argues that "Without a doubt, a lone man could not achieve this transformation. It is rather a development which shook the Muslim world in general ..."
He created a new type of deodorant to get rid of bad odors and also promoted morning and evening baths and emphasized the maintenance of personal hygiene. Ziryab is thought to have invented an early toothpaste, which he popularized throughout Islamic Iberia. The exact ingredients of this toothpaste are not currently known, but it was reported to have been both "functional and pleasant to taste".
According to Al-Maqqari before the arrival of Ziryab, all the people of al-Andalus, in the Cordoban court, wore their long hair parted in the middle and hung down loose down to the shoulders, men and women; Ziryab had his hair cut with bangs down to his eyebrows and straight across his forehead, "new short hairstyles leaving the neck, ears and eyebrows free,". He popularized shaving among men and set new haircut trends. Royalty used to wash their hair with rose water, but Ziryab introduced the use of salt and fragrant oils to improve the hair's condition. He is alleged by some to have opened beauty parlors for women of the Cordoban elite. However, this is not supported by the early sources.
Ziryab was a "major trendsetter of his time" creating trends in fashion, hairstyles, and hygiene. His students took these trends with them throughout Europe and North Africa. | 1 | Applied and Interdisciplinary Chemistry |
Unsolved problems have been used to indicate a rare mathematical talent in fiction. The Navier–Stokes problem features in The Mathematicians Shiva (2014), a book about a prestigious, deceased, fictional mathematician named Rachela Karnokovitch taking the proof to her grave in protest of academia. The movie Gifted' (2017) referenced the Millennium Prize problems and dealt with the potential for a 7-year-old girl and her deceased mathematician mother for solving the Navier–Stokes problem. | 1 | Applied and Interdisciplinary Chemistry |
First, the coverage and quality of an interactome has to be evaluated. Interactomes are never complete, given the limitations of experimental methods. For instance, it has been estimated that typical Y2H screens detect only 25% or so of all interactions in an interactome. The coverage of an interactome can be assessed by comparing it to benchmarks of well-known interactions that have been found and validated by independent assays. Other methods filter out false positives calculating the similarity of known annotations of the proteins involved or define a likelihood of interaction using the subcellular localization of these proteins. | 1 | Applied and Interdisciplinary Chemistry |
A Markov process is called a reversible Markov process or reversible Markov chain if it satisfies the detailed balance equations. These equations require that the transition probability matrix P for the Markov process possess a stationary distribution (i.e. equilibrium probability distribution) π such that
where P is the Markov transition probability from state i to state j, i.e. , and π and π are the equilibrium probabilities of being in states i and j, respectively. When for all i, this is equivalent to the joint probability matrix, being symmetric in i and j; or symmetric in and t.
The definition carries over straightforwardly to continuous variables, where π becomes a probability density, and a transition kernel probability density from state s′ to state s:
The detailed balance condition is stronger than that required merely for a stationary distribution; that is, there are Markov processes with stationary distributions that do not have detailed balance. Detailed balance implies that, around any closed cycle of states, there is no net flow of probability. For example, it implies that, for all a, b and c,
This can be proved by substitution from the definition. In the case of a positive transition matrix, the "no net flow" condition implies detailed balance. Indeed, a necessary and sufficient condition for the reversibility condition is Kolmogorov's criterion, which demands that for the reversible chains the product of transition rates over any closed loop of states must be the same in both directions.
Transition matrices that are symmetric or always have detailed balance. In these cases, a uniform distribution over the states is an equilibrium distribution. For continuous systems with detailed balance, it may be possible to continuously transform the coordinates until the equilibrium distribution is uniform, with a transition kernel which then is symmetric. In the case of discrete states, it may be possible to achieve something similar by breaking the Markov states into appropriately-sized degenerate sub-states.
For a Markov transition matrix and a stationary distribution, the detailed balance equations may not be valid. However, it can be shown that a unique Markov transition matrix exists which is closest according to the stationary distribution and a given norm. The closest Matrix can be computed by solving a quadratic-convex optimization problem. For more details see Closest reversible Markov chain | 0 | Theoretical and Fundamental Chemistry |
According to the United States National Library of Medicines medical subject headings, the term neurotrophin may be used as a synonym for neurotrophic factor, but the term neurotrophin is more generally reserved for four structurally related factors: nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). The term neurotrophic factor' generally refers to these four neurotrophins, the GDNF family of ligands, and ciliary neurotrophic factor (CNTF), among other biomolecules. Neurotrophin-6 and neurotrophin-7 also exist, but are only found in zebrafish. | 1 | Applied and Interdisciplinary Chemistry |
The coupling of chromatography with MS is a well developed chemical analysis strategy dating back from the 1950s. Gas chromatography (GC)–MS was originally introduced in 1952, when A. T. James and A. J. P. Martin were trying to develop tandem separation – mass analysis techniques. In GC, the analytes are eluted from the separation column as a gas and the connection with electron ionization (EI) or chemical ionization (CI) ion sources in the MS system was a technically simpler challenge. Because of this, the development of GC-MS systems was faster than LC–MS and such systems were first commercialized in the 1970s. The development of LC–MS systems took longer than GC-MS and was directly related to the development of proper interfaces. Victor Talrose and his collaborators in Russia started the development of LC–MS in the late 1960s, when they first used capillaries to connect an LC columns to an EI source. A similar strategy was investigated by McLafferty and collaborators in 1973 who coupled the LC column to a CI source, which allowed a higher liquid flow into the source. This was the first and most obvious way of coupling LC with MS, and was known as the capillary inlet interface. This pioneer interface for LC–MS had the same analysis capabilities of GC-MS and was limited to rather volatile analytes and non-polar compounds with low molecular mass (below 400 Da). In the capillary inlet interface, the evaporation of the mobile phase inside the capillary was one of the main issues. Within the first years of development of LC–MS, on-line and off-line alternatives were proposed as coupling alternatives. In general, off-line coupling involved fraction collection, evaporation of solvent, and transfer of analytes to the MS using probes. Off-line analyte treatment process was time-consuming and there was an inherent risk of sample contamination. Rapidly, it was realized that the analysis of complex mixtures would require the development of a fully automated on-line coupling solution in LC–MS.
The key to the success and widespread adoption of LC–MS as a routine analytical tool lies in the interface and ion source between the liquid-based LC and the vacuum-base MS. The following interfaces were stepping-stones on the way to the modern atmospheric-pressure ionization interfaces, and are described for historical interest. | 0 | Theoretical and Fundamental Chemistry |
The method was improved by Draine, Flatau, and Goodman, who applied the fast Fourier transform to solve fast convolution problems arising in the discrete dipole approximation (DDA). This allowed for the calculation of scattering by large targets. They distributed an open-source code DDSCAT.
There are now several DDA implementations, extensions to periodic targets, and particles placed on or near a plane substrate. Comparisons with exact techniques have also been published.
Other aspects, such as the validity criteria of the discrete dipole approximation, were published. The DDA was also extended to employ rectangular or cuboid dipoles, which are more efficient for highly oblate or prolate particles. | 0 | Theoretical and Fundamental Chemistry |
The first law gives rise to the following formula:
in which
* is the permeability, an experimentally determined membrane "conductance" for a given gas at a given temperature.
* is the difference in concentration of the gas across the membrane for the direction of flow (from to ).
Fick's first law is also important in radiation transfer equations. However, in this context, it becomes inaccurate when the diffusion constant is low and the radiation becomes limited by the speed of light rather than by the resistance of the material the radiation is flowing through. In this situation, one can use a flux limiter.
The exchange rate of a gas across a fluid membrane can be determined by using this law together with Graham's law.
Under the condition of a diluted solution when diffusion takes control, the membrane permeability mentioned in the above section can be theoretically calculated for the solute using the equation mentioned in the last section (use with particular care because the equation is derived for dense solutes, while biological molecules are not denser than water):
where
* is the total area of the pores on the membrane (unit m).
* transmembrane efficiency (unitless), which can be calculated from the stochastic theory of chromatography.
* D is the diffusion constant of the solute unit m⋅s.
* t is time unit s.
* c, c concentration should use unit mol m, so flux unit becomes mol s.
The flux is decay over the square root of time because a concentration gradient builds up near the membrane over time under ideal conditions. When there is flow and convection, the flux can be significantly different than the equation predicts and show an effective time t with a fixed value, which makes the flux stable instead of decay over time. A critical time has been estimated under idealized flow conditions when there is no gradient formed. This strategy is adopted in biology such as blood circulation. | 0 | Theoretical and Fundamental Chemistry |
While it is well known that the genome of one individual can have extensive differences when compared to the genome of another, recent research has found that some coding regions are highly constrained, or resistant to mutation, between individuals of the same species. This is similar to the concept of interspecies constraint in conserved sequences. Researchers termed these highly constrained sequences constrained coding regions (CCRs), and have also discovered that such regions may be involved in high purifying selection. On average, there is approximately 1 protein-altering mutation every 7 coding bases, but some CCRs can have over 100 bases in sequence with no observed protein-altering mutations, some without even synonymous mutations. These patterns of constraint between genomes may provide clues to the sources of rare developmental diseases or potentially even embryonic lethality. Clinically validated variants and de novo mutations in CCRs have been previously linked to disorders such as infantile epileptic encephalopathy, developmental delay and severe heart disease. | 1 | Applied and Interdisciplinary Chemistry |
Ellen Gleditsch was born in 1879 in Mandal, Norway. She was the daughter of Petra Birgitte Hansen (1857–1913) and headmaster Karl Kristian Gleditsch (1851–1913). Her siblings included architect Eivind Gleditsch(nl), Adler (1893–1978) who lived with her for the rest of her life following the death of their parents, Liv Gleditsch (1895–1977) who graduated with a degree in chemistry, and civil engineer and geodesist Kristian Gleditsch. The family moved to Trondhjem and then Fredrikshald in 1905. She was the niece of Jens Gran Gleditsch and Kristen Gran Gleditsch, a first cousin of Henry Gleditsch and second cousin of Rolf Juell Gleditsch and Odd Gleditsch, Sr. Her sister in law through Kristian was Nini Haslund Gleditsch (1908–1996).
Although she graduated from high school at the top of her class, the college entrance exams were not available to women at the time. Therefore, she worked as a pharmacy assistant where she was able to work toward a non-academic degree in chemistry and pharmacology in 1902. In 1905 with the support of her mentor Eyvind Bødtker, she passed the university entrance exam, but chose to study in Paris. | 0 | Theoretical and Fundamental Chemistry |
Tetracyclics are cyclic chemical compounds that contain four fused rings of atoms, for example, Tröger's base.
Some tricyclic compounds having three fused and one tethered ring (connected to main nucleus by a single bond) can also classified as tetracyclic, for example, ciclazindol.
Tetracyclic compounds have various pharmaceutical uses, such as:
*tetracycline antibiotics
**Doxycycline
**Tigecycline
**Omadacycline
**Eravacycline
*tetracyclic antidepressants
**Benzoctamine
**Loxapine
**Mazindol
**Mianserin
**Mirtazapine | 0 | Theoretical and Fundamental Chemistry |
When the mean free path of an atom is much smaller than the wavelength of the radiative transition, the atom changes velocity and direction many times during the emission or absorption of a photon. This causes an averaging over different Doppler states and results in an atomic linewidth that is narrower than the Doppler width. | 0 | Theoretical and Fundamental Chemistry |
The dienone–phenol rearrangement is a reaction in organic chemistry first reported in 1921 by Karl von Auwers and Karl Ziegler. A common example of dienone–phenol rearrangement is 4,4-disubstituted converting into a stable 3,4-disubstituted phenol in presence of acid. A similar rearrangement is possible with a 2,2-disubstituted cyclohexadienone to its corresponding disubstituted phenol. Usually this type of rearrangement is spontaneous unless a dichloromethyl group is present at the 4th position or the process is otherwise blocked. | 0 | Theoretical and Fundamental Chemistry |
Hydraulic jumps occur in the atmosphere in the air flowing over mountains. A hydraulic jump also occurs at the tropopause interface between the stratosphere and troposphere downwind of the overshooting top of very strong supercell thunderstorms. A related situation is the Morning Glory cloud observed, for example, in Northern Australia, sometimes called an undular jump. | 1 | Applied and Interdisciplinary Chemistry |
The molecule CSPD has the following functional groups in the structure: phosphate group, phenyl group, spiro group, methyl ether group, and chlorine group. The ones worth noting are the ones above. None of these groups carry a charge. If there was a charge this would have had a change in the compound's pH, 3D structure, mass and bond angles.
The toxin CSPD effect persister cell formation using MqsR (MqsR, a crucial regulator for quorum sensing and biofilm formation, is a GCU-specific mRNA interferase in Escherichia coli) and persister cells are cells that avoid stress and are characterized by reduced metabolism and other factors. | 1 | Applied and Interdisciplinary Chemistry |
Micro RNAs (miRNAs) are short, ~19-23 base pair long RNA oligonucleotides that are involved in the microRNA-induced silencing complex. Specifically, once loaded onto the ARGONAUTE enzyme, miRNAs work with mRNAs to repress translation and post-translationally destabilize mRNA. While they are functionally similar to siRNAs, miRNAs do not require extensive base-pairing for mRNA silencing (can require as few as seven base-pairs with target), thus allowing them to broadly affect a wider range of mRNA targets. In the cell, miRNA uses switch, tuning, and neutral interactions to finely regulate gene repression. As a therapeutic, miRNA has the potential to affect biochemical pathways throughout the organism.
With more than 400 miRNA identified in humans, discerning their target gene for repression is the first challenge. Multiple databases have been built, for example TargetScan, using miRNA seed matching. In vitro assays assist in determining the phenotypic effects of miRNAs, but due to the complex nature of gene regulation not all identified miRNAs have the expected effect. Additionally, several miRNAs have been found to act as either tumor suppressors or oncogenes in vivo, such as the oncogenic miR-155 and miR-17-92.
In clinical trials, miRNA are commonly used as biomarkers for a variety of diseases, potentially providing earlier diagnosis as well as disease progression, stage, and genetic links. Phase 1 and 2 trials currently test miRNA mimics (to express genes) and miRNA (to repress genes) in patients with cancers and other diseases. In particular, mimic miRNAs are used to introduce miRNAs that act as tumor suppressors into cancerous tissues, while miRNA antagonists are used to target oncogenic miRNAs to prevent their cancer-promoting activity. Therapeutic miRNA is also used in addition to common therapies (such as cancer therapies) that are known to overexpress or destabilize the patient miRNA levels. An example of one mimic miRNA therapy that demonstrated efficacy in impeding lung cancer tumor growth in mouse studies is miR-34a.
One concerning aspect of miRNA-based therapies is the potential for the exogeneous miRNA to affect miRNA silencing mechanisms within normal body cells, thereby affecting normal cellular biochemical pathways. However, in vivo studies have indicated that miRNAs display little to no effect in non-target tissues/organs. | 1 | Applied and Interdisciplinary Chemistry |
In 1986, Professor Hugo Karl Messerle at The University of Sydney researched coal-fueled MHD. This resulted in a 28MWe topping facility that was operated outside Sydney. Messerle also wrote one of the most recent reference works (see below), as part of a UNESCO education program.
A detailed obituary for Hugo is located on the Australian Academy of Technological Sciences and Engineering (ATSE) website. | 1 | Applied and Interdisciplinary Chemistry |
Various AMMs have been designed with a broad range of functions and applications, several of which have been tabulated below along with indicative images: | 0 | Theoretical and Fundamental Chemistry |
An integrated constructed wetland is an unlined free surface flow constructed wetland with emergent vegetated areas and local soil material. Its objectives is not only to treat wastewater from farmyards and other wastewater sources, but also to integrate the wetland infrastructure into the landscape and enhancing its biological diversity.
Integrated constructed wetland facilitates may be more robust treatment systems compared to other constructed wetlands. This is due to the greater biological complexity and generally relatively larger land area use and associated longer hydraulic residence time of integrated constructed wetland compared to conventional constructed wetlands.
Integrated constructed wetlands are used in Ireland, the UK and the United States since about 2007. Farm constructed wetlands, which are a subtype of integrated constructed wetlands, are promoted by the Scottish Environment Protection Agency and the Northern Ireland Environment Agency since 2008. | 1 | Applied and Interdisciplinary Chemistry |
Platinum-samarium forms crystals of rhombic crystal system, space group P nma, cell parameters a = 0.7148 nm, b = 0.4501 nm, c = 0.5638 nm, Z = 4, structure similar to that of iron boride (FeB).
The compound melts congruently at a temperature of ≈1810 °C. | 1 | Applied and Interdisciplinary Chemistry |
Sulfur dioxide forms complexes with many transition metals. Most numerous are complexes with metals i in oxidation state 0 or +1.
In most cases SO binds in monodentate fashion, attaching to the metal through sulfur. Such complexes are further subdivided according to the planarity or pyramidalization at sulfur. The various bonding modes are:
*η-SO, planar (meaning that the MSO subunit forms a plane). In such complexes, SO is classified as a 2e donor complemented by pi-back bonding into the empty p orbital localized on sulfur.
*η-SO, pyramidal (meaning that the MSO subunit is pyramidal at sulfur). In such complexes, SO is classified as a pure Lewis acid. The structure is similar to that for conventional Lewis base adducts of SO.
*η-SO. Both S and one O centre are attached to the metal. The MSO subunit is pyramidal at sulfur. This bonding mode is more common for early metals, which are typically strongly pi-donating.
*η-SO, O-bonded. In such cases, SO attaches to a metal via one of its two oxygen centres. Such complexes are prevalent for hard metal cations such as Na and Al. In these compounds the M-O interaction is usually weak.
More exotic bonding modes are known for clusters. | 0 | Theoretical and Fundamental Chemistry |
Ideal materials for thermal mass are those materials that have:
* high specific heat capacity,
* high density
Any solid, liquid, or gas that has mass will have some thermal mass. A common misconception is that only concrete or earth soil has thermal mass; even air has thermal mass (although very little).
A table of volumetric heat capacity for building materials is available, but note that their definition of thermal mass is slightly different. | 0 | Theoretical and Fundamental Chemistry |
:The following carbon numbering system of porphyrins is an older numbering used by biochemists and not the 1–24 numbering system recommended by IUPAC, which is shown in the table above.
*Heme l is the derivative of heme B which is covalently attached to the protein of lactoperoxidase, eosinophil peroxidase, and thyroid peroxidase. The addition of peroxide with the glutamyl-375 and aspartyl-225 of lactoperoxidase forms ester bonds between these amino acid residues and the heme 1- and 5-methyl groups, respectively. Similar ester bonds with these two methyl groups are thought to form in eosinophil and thyroid peroxidases. Heme l is one important characteristic of animal peroxidases; plant peroxidases incorporate heme B. Lactoperoxidase and eosinophil peroxidase are protective enzymes responsible for the destruction of invading bacteria and virus. Thyroid peroxidase is the enzyme catalyzing the biosynthesis of the important thyroid hormones. Because lactoperoxidase destroys invading organisms in the lungs and excrement, it is thought to be an important protective enzyme.
*Heme m is the derivative of heme B covalently bound at the active site of myeloperoxidase. Heme m contains the two ester bonds at the heme 1- and 5-methyl groups also present in heme l of other mammalian peroxidases, such as lactoperoxidase and eosinophil peroxidase. In addition, a unique sulfonamide ion linkage between the sulfur of a methionyl amino-acid residue and the heme 2-vinyl group is formed, giving this enzyme the unique capability of easily oxidizing chloride and bromide ions to hypochlorite and hypobromite. Myeloperoxidase is present in mammalian neutrophils and is responsible for the destruction of invading bacteria and viral agents. It perhaps synthesizes hypobromite by "mistake". Both hypochlorite and hypobromite are very reactive species responsible for the production of halogenated nucleosides, which are mutagenic compounds.
*Heme D is another derivative of heme B, but in which the propionic acid side chain at the carbon of position 6, which is also hydroxylated, forms a γ-spirolactone. Ring III is also hydroxylated at position 5, in a conformation trans to the new lactone group. Heme D is the site for oxygen reduction to water of many types of bacteria at low oxygen tension.
*Heme S is related to heme B by having a formyl group at position 2 in place of the 2-vinyl group. Heme S is found in the hemoglobin of a few species of marine worms. The correct structures of heme B and heme S were first elucidated by German chemist Hans Fischer.
The names of cytochromes typically (but not always) reflect the kinds of hemes they contain: cytochrome a contains heme A, cytochrome c contains heme C, etc. This convention may have been first introduced with the publication of the structure of heme A. | 1 | Applied and Interdisciplinary Chemistry |
The manufacturing process of recombinant subunit vaccines are as follows:
# Identification of immunogenic subunit
# Subunit expression and synthesis
# Extraction and purification
# Addition of adjuvants or incorporation to vectors
# Formulation and delivery. | 1 | Applied and Interdisciplinary Chemistry |
In this type of plot (Figure 1), each axis represents a unique reaction coordinate, the corners represent local minima along the potential surface such as reactants, products or intermediates and the energy axis projects vertically out of the page. Changing a single reaction parameter can change the height of one or more of the corners of the plot. These changes are transmitted across the surface such that the position of the transition state (the saddle point) is altered.
Consider a generic example in which the initial transition state along a concerted pathway is represented by a black dot on a red diagonal (Figure 1). Changing the height of the corners can have two effects on the position of the transition state: it can move along the diagonal, reflecting a change in the Gibbs free energy of the reaction (ΔG°), or perpendicular to it, reflecting a change in the energy of competing pathways. Thus, in accordance with the Hammond postulate, the transition state moves along the diagonal towards the corner that is raised in energy (a Hammond effect) and perpendicular to the diagonal towards the corner that is lowered (an anti-Hammond effect). In this example, R is raised in energy and I(2) is lowered in energy. The transition state moves accordingly and the vector sum of both movements gives the real change in its position. | 0 | Theoretical and Fundamental Chemistry |
EosFP is a photoactivatable green to red fluorescent protein. Its green fluorescence (516 nm) switches to red (581 nm) upon UV irradiation of ~390 nm (violet/blue light) due to a photo-induced modification resulting from a break in the peptide backbone near the chromophore. Eos was first discovered as a tetrameric protein in the stony coral Lobophyllia hemprichii. Like other fluorescent proteins, Eos allows for applications such as the tracking of fusion proteins, multicolour labelling and tracking of cell movement. Several variants of Eos have been engineered for use in specific study systems including mEos2, mEos4 and CaMPARI. | 1 | Applied and Interdisciplinary Chemistry |
In analytical chemistry, a chiral derivatizing agent (CDA), also known as a chiral resolving reagent, is a derivatization reagent that is a chiral auxiliary used to convert a mixture of enantiomers into diastereomers in order to analyze the quantities of each enantiomer present and determine the optical purity of a sample. Analysis can be conducted by spectroscopy or by chromatography. Some analytical techniques such as HPLC and NMR, in their most commons forms, cannot distinguish enantiomers within a sample, but can distinguish diastereomers. Therefore, converting a mixture of enantiomers to a corresponding mixture of diastereomers can allow analysis. The use of chiral derivatizing agents has declined with the popularization of chiral HPLC. Besides analysis, chiral derivatization is also used for chiral resolution, the actual physical separation of the enantiomers. | 0 | Theoretical and Fundamental Chemistry |
If the characteristic length is defined
where is the surface area of the plate and is its perimeter.
Then for the top surface of a hot object in a colder environment or bottom surface of a cold object in a hotter environment
And for the bottom surface of a hot object in a colder environment or top surface of a cold object in a hotter environment | 1 | Applied and Interdisciplinary Chemistry |
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