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Functional null mutations in this gene cause Carney complex (CNC), an autosomal dominant multiple neoplasia syndrome. This gene can fuse to the RET protooncogene by gene rearrangement and form the thyroid tumor-specific chimeric oncogene known as PTC2.
Mutation of PRKAR1A leads to the Carney complex, associating multiple endocrine tumors. | 1 | Applied and Interdisciplinary Chemistry |
Okazaki fragments are present in both prokaryotes and eukaryotes. DNA molecules in eukaryotes differ from the circular molecules of prokaryotes in that they are larger and usually have multiple origins of replication. This means that each eukaryotic chromosome is composed of many replicating units of DNA with multiple origins of replication. In comparison, prokaryotic DNA has only a single origin of replication. In eukaryotes, these replicating forks, which are numerous all along the DNA, form "bubbles" in the DNA during replication. The replication fork forms at a specific point called autonomously replicating sequences (ARS). Eukaryotes have a clamp loader complex and a six-unit clamp called the proliferating cell nuclear antigen. The efficient movement of the replication fork also relies critically on the rapid placement of sliding clamps at newly primed sites on the lagging DNA strand by ATP-dependent clamp loader complexes. This means that the piecewise generation of Okazaki fragments can keep up with the continuous synthesis of DNA on the leading strand. These clamp loader complexes are characteristic of all eukaryotes and separate some of the minor differences in the synthesis of Okazaki fragments in prokaryotes and eukaryotes.
The lengths of Okazaki fragments in prokaryotes and eukaryotes are different as well. Prokaryotes have Okazaki fragments that are quite longer than those of eukaryotes. Eukaryotes typically have Okazaki fragments that are 100 to 200 nucleotides long, whereas fragments in prokaryotic E. coli can be 2,000 nucleotides long. The reason for this discrepancy is unknown.
Each eukaryotic chromosome is composed of many replicating units of DNA with multiple origins of replication. In comparison, the prokaryotic E. coli chromosome has only a single origin of replication. Replication in prokaryotes occurs inside of the cytoplasm, and this all begins the replication that is formed of about 100 to 200 or more nucleotides. Eukaryotic DNA molecules have a significantly larger number of replicons, about 50,000 or more; however, replication does not occur at the same time on all of the replicons. In eukaryotes, DNA replication takes place in the nucleus. A plethora replication form in just one replicating DNA molecule, the start of DNA replication is moved away by the multi-subunit protein. This replication is slow, and sometimes about 100 nucleotides per second are added.
We take from this that prokaryotic cells are simpler in structure, they have no nucleus, organelles, and very little of DNA, in the form of a single chromosome. Eukaryotic cells have nucleus with multiple organelles and more DNA arranged in linear chromosomes. We also see that the size is another difference between these prokaryotic and eukaryotic cells. The average eukaryotic cell has about 25 times more DNA than a prokaryotic cell does. Replication occurs much faster in prokaryotic cells than in eukaryotic cells; bacteria sometimes only take 40 minutes, while animal cells can take up to 400 hours. Eukaryotes also have a distinct operation for replicating the telomeres at the end of their last chromosomes. Prokaryotes have circular chromosomes, causing no ends to synthesize. Prokaryotes have a short replication process that occurs continuously; eukaryotic cells, on the other hand, only undertake DNA replication during the S-phase of the cell cycle.
The similarities are the steps for the DNA replication. In both prokaryotes and eukaryotes, replication is accomplished by unwinding the DNA by an enzyme called the DNA helicase. New strands are created by enzymes called DNA polymerases. Both of these follow a similar pattern, called semi-conservative replication, in which individual strands of DNA are produced in different directions, which makes a leading and lagging strand. These lagging strands are synthesized by the production of Okazaki fragments that are soon joined. Both of these organisms begin new DNA strands which also include small strands of RNA. | 1 | Applied and Interdisciplinary Chemistry |
In genetics, attenuation is a regulatory mechanism for some bacterial operons that results in premature termination of transcription. The canonical example of attenuation used in many introductory genetics textbooks, is ribosome-mediated attenuation of the trp operon. Ribosome-mediated attenuation of the trp operon relies on the fact that, in bacteria, transcription and translation proceed simultaneously. Attenuation involves a provisional stop signal (attenuator), located in the DNA segment that corresponds to the leader sequence of mRNA. During attenuation, the ribosome becomes stalled (delayed) in the attenuator region in the mRNA leader. Depending on the metabolic conditions, the attenuator either stops transcription at that point or allows read-through to the structural gene part of the mRNA and synthesis of the appropriate protein.
Attenuation is a regulatory feature found throughout Archaea and Bacteria causing premature termination of transcription. Attenuators are 5-cis' acting regulatory regions which fold into one of two alternative RNA structures which determine the success of transcription. The folding is modulated by a sensing mechanism producing either a Rho-independent terminator, resulting in interrupted transcription and a non-functional RNA product; or an anti-terminator structure, resulting in a functional RNA transcript. There are now many equivalent examples where the translation, not transcription, is terminated by sequestering the Shine-Dalgarno sequence (ribosomal binding site) in a hairpin-loop structure. While not meeting the previous definition of (transcriptional) attenuation, these are now considered to be variants of the same phenomena and are included in this article. Attenuation is an ancient regulatory system, prevalent in many bacterial species providing fast and sensitive regulation of gene operons and is commonly used to repress genes in the presence of their own product (or a downstream metabolite). | 1 | Applied and Interdisciplinary Chemistry |
In thermodynamics, the particle number (symbol ) of a thermodynamic system is the number of constituent particles in that system. The particle number is a fundamental thermodynamic property which is conjugate to the chemical potential. Unlike most physical quantities, the particle number is a dimensionless quantity, specifically a countable quantity. It is an extensive property, as it is directly proportional to the size of the system under consideration and thus meaningful only for closed systems.
A constituent particle is one that cannot be broken into smaller pieces at the scale of energy involved in the process (where is the Boltzmann constant and is the temperature). For example, in a thermodynamic system consisting of a piston containing water vapour, the particle number is the number of water molecules in the system. The meaning of constituent particles, and thereby of particle numbers, is thus temperature-dependent. | 0 | Theoretical and Fundamental Chemistry |
A single jet meter consists of a simple impeller with radial vanes, impinged upon by a single jet. They are increasing in popularity in the UK at larger sizes and are commonplace in the EU. | 1 | Applied and Interdisciplinary Chemistry |
An endothermic process is a chemical or physical process that absorbs heat from its surroundings. In terms of thermodynamics and thermochemistry, it is a thermodynamic process with an increase in the enthalpy (or internal energy ) of the system. In an endothermic process, the heat that a system absorbs is thermal energy transfer into the system. Thus, an endothermic reaction generally leads to an increase in the temperature of the system and a decrease in that of the surroundings.
The term was coined by 19th-century French chemist Marcellin Berthelot. The term endothermic comes from the Greek ἔνδον (endon) meaning within and θερμ- (therm) meaning hot or warm.
An endothermic process may be a chemical process, such as dissolving ammonium nitrate () in water (), or a physical process, such as the melting of ice cubes.
The opposite of an endothermic process is an exothermic process, one that releases or "gives out" energy, usually in the form of heat and sometimes as electrical energy. Thus, endo in endothermic refers to energy or heat going in, and exo in exothermic refers to energy or heat going out. In each term (endothermic and exothermic) the prefix refers to where heat (or electrical energy) goes as the process occurs. | 0 | Theoretical and Fundamental Chemistry |
The Wien effect is the experimentally-observed increase in ionic mobility or conductivity of electrolytes at very high gradient of electrical potential. A theoretical explanation has been proposed by Lars Onsager.
A related phenomenon is known as the Second Wien Effect or the dissociation field effect, and it involves increased dissociation constants of weak acids at high electrical gradients. The dissociation of weak chemical bases is unaffected.
The effects are important at very high electrical fields (10 – 10 V/m), like those observed in electrical double layers at interfaces or at the surfaces of electrodes in electrochemistry.
More generally, the electric field effect (directly, through space rather than through chemical bonds) on chemical behaviour of systems (e.g., on reaction rates) is known as the field effect or the direct effect.
The terms are named after Max Wien. | 0 | Theoretical and Fundamental Chemistry |
Ants typically use trail pheromones to coordinate roles like nest defense and foraging. Ants can produce a trail of defensive secretions that trigger an alarm response within their nestmates. In regards to foraging, an ant can communicate the quality of a food source to its colony; the more rewarding a food source is, the higher the concentration of the trail produced. Additionally, some species, like Lasius niger ants, can "eavesdrop" on the trails produced by another species in order to procure food.
Myrmicine ants produce their trail pheromones through their poison glands. The major component in the trail pheromones secreted by Pristomyrex pungens is 6-n-pentyl-2-pyrone; several monoterpenes were also found in the secretion, but they provided only marginal effects when combined with the former. The major components found in the secretions of Aphaenogaster rudis include anabaseine, anabasine, and 2,3'-bipyridyl, though the third contributes less than the other two. When secreted, this trail pheromone does not recruit ants directly from their nest; instead, worker ants may stumble upon to the trail unintentionally and follow it thereafter to the food source. | 1 | Applied and Interdisciplinary Chemistry |
Annulenes may be aromatic (benzene, [6]annulene and [18]annulene), non-aromatic ([8] and [10]annulene), or anti-aromatic (cyclobutadiene, [4]annulene). Cyclobutadiene is the only annulene with considerable antiaromaticity, since planarity is unavoidable. With [8]annulene, the molecule takes on a tub shape that allows it to avoid conjugation of double bonds. [10]Annulene is of the wrong size to achieve a planar structure: in a planar conformation, ring strain due to either steric hindrance of internal hydrogens (when some double bonds are trans) or bond angle distortion (when the double bonds are all cis) is unavoidable. Thus, it does not exhibit appreciable aromaticity.
When the annulene is large enough, [18]annulene for example, there is enough room internally to accommodate hydrogen atoms without significant distortion of bond angles. [18]Annulene possesses several properties that qualify it as aromatic. However, none of the larger annulenes are as stable as benzene, as their reactivity more closely resembles a conjugated polyene than an aromatic hydrocarbon.
In general, charged annulene species of the form [CH] (n = 0, 1, 2, ..., q = 0, ±1, ±2, 4n + 2 + q ≥ 3) are aromatic, provided a planar conformation can be achieved. For instance, CH, CH, and CH are all known aromatic species. | 0 | Theoretical and Fundamental Chemistry |
The ENCyclOpedia of Rna Epitranscriptome (ENCORE) is an upgraded version of [https://rna.sysu.edu.cn/encore/index.php RMBase] that a comprehensive epitranscriptome platform with tens of new software and tools, to decode the distribution pattern, metagene profile, biogenesis mechanisms, regulatory functions, interactome, evolutional conservation and novel reader proteins of more than 70 different types of RNA modifications by analyzing thousands of high-throughput sequencing data. | 1 | Applied and Interdisciplinary Chemistry |
The theory that metallurgy was imported into Europe from the Near East has been practically ruled out. A second hypothesis, that there were two main points of origin of metallurgy in Europe, in southern Spain and in West Bulgaria, is also doubtful due to the existence of sites outside the centers of diffusion where metallurgy was known simultaneously with, or before, those in the ‘original’ nuclei, such as Brixlegg (Tyrol, Austria), while sites closer to the supposed origins of metallurgy, such as in the north of Spain, show fewer metal artifacts than sites in the south and practically no evidence of production.
Currently, the general opinion is that the development of metallurgy took place independently in different places, at different times, with various techniques. One fact that supports this interpretation is that, although the final products (beads, rings, sickles, swords, axes, etc.) are quite similar throughout Europe, the method of production is not. Thus the use of crucibles was the technique utilized in the south of Spain, whereas central Europe employed a slagging process, but Cabrierés (France) used a primitive oxidizing non-slagging process, while in the British Isles the absence of debris, slag or ceramic suggests another technique.
Consequently, the way in which metallurgy was initiated differs considerably depending on the region. There are areas in which copper seems to play a crucial role (i.e., the Balkans), whereas other areas show no interest in it at all. Then there are societies that use copper artifacts, but do not practice metallurgy, and there are other ones that fully adopt some of the cultural innovations but ignore the rest. One example of the latter is Basque country in northern Spain, where splendid large dolmens are present along the Ebro river, but metal is rather infrequent, and when it does appear between the trapping, it is more often bronze or arsenical copper than copper. According to radiocarbon dating, the Pre-Bell Beaker Chalcolithic with copper metallurgy began on the Iberian Peninsula in the last third of the IV millennium cal. BC, in the Northern Iberian Plateau in 3000 cal. BC and the Bell Beaker Chalcolithic appeared around 2500 cal. BC. | 1 | Applied and Interdisciplinary Chemistry |
In healthy adults, the normal concentrations of CRP varies between 0.8 mg/L and 3.0 mg/L. However, some healthy adults show elevated CRP at 10 mg/L. CRP concentrations also increase with age, possibly due to subclinical conditions. There are also no seasonal variations of CRP concentrations. Gene polymorphism of interleukin-1 family, interleukin 6, and polymorphic GT repeat of the CRP gene do affect the usual CRP concentrations when a person does not have any medical illnesses. | 1 | Applied and Interdisciplinary Chemistry |
Ecdysteroids are arthropod steroid hormones that are mainly responsible for molting, development and, to a lesser extent, reproduction; examples of ecdysteroids include ecdysone, ecdysterone, turkesterone and 2-deoxyecdysone. These compounds are synthesized in arthropods from dietary cholesterol upon metabolism by the Halloween family of cytochrome P450s. Phytoecdysteroids also appear in many plants mostly as a protection agents (toxins or antifeedants) against herbivore insects.
Ecdysterone has been tested on mammals due to the interest in its potential hypertrophic effect. It has been found to increase hypertrophy in rats at a similar level to some anabolic androgenic steroids and SARM S 1. This is proposed to be through increase of Calcium leading to activation of Akt and protein synthesis in skeletal muscles. | 1 | Applied and Interdisciplinary Chemistry |
Open pond systems consist of simple in ground ponds, which are often mixed by a paddle wheel. These systems have low power requirements, operating costs, and capital costs when compared to closed loop photobioreactor systems. Nearly all commercial algae producers for high value algal products utilize open pond systems. | 1 | Applied and Interdisciplinary Chemistry |
The acetonides of small di- and triols, as well as many sugars and sugar alcohols, are common. The hexaol mannitol reacts with 2,2-dimethoxypropane to give the bis-acetonide, which oxidizes to give the acetonide of glyceraldehyde:
:(CHOHCHOHCHOH) + 2 (MeO)CMe → (CHOHCHCHOCMe) + 4 MeOH
:(CHOHCHOCHOCMe) + [O] → 2 OCHCHCHOCMe + HO
An example of its use as a protecting group in a complex organic synthesis is the Nicolaou Taxol total synthesis. It is a common protecting group for sugars and sugar alcohols, a simple example being solketal.
The acetonides of corticosteroid are used in dermatology, because their increased lipophilicity leads to better penetration into the skin.
* Fluclorolone acetonide
* Fluocinolone acetonide
* Triamcinolone acetonide | 0 | Theoretical and Fundamental Chemistry |
There is an association between high intake of heme iron sourced from meat and increased risk of colorectal cancer.
The American Institute for Cancer Research (AICR) and World Cancer Research Fund International (WCRF) concluded in a 2018 report that there is limited but suggestive evidence that foods containing heme iron increase risk of colorectal cancer. A 2019 review found that heme iron intake is associated with increased breast cancer risk. | 1 | Applied and Interdisciplinary Chemistry |
Many mutagens are highly toxic to proliferating cells, and they are often used to destroy cancer cells. Alkylating agents such as cyclophosphamide and cisplatin, as well as intercalating agent such as daunorubicin and doxorubicin may be used in chemotherapy. However, due to their effect on other cells which are also rapidly dividing, they may have side effects such as hair loss and nausea. Research on better targeted therapies may reduce such side-effects. Ionizing radiations are used in radiation therapy. | 0 | Theoretical and Fundamental Chemistry |
One of the most commonly used practices to quantitate DNA or RNA is the use of spectrophotometric analysis using a spectrophotometer. A spectrophotometer is able to determine the average concentrations of the nucleic acids DNA or RNA present in a mixture, as well as their purity.
Spectrophotometric analysis is based on the principles that nucleic acids absorb ultraviolet light in a specific pattern. In the case of DNA and RNA, a sample is exposed to ultraviolet light at a wavelength of 260 nanometres (nm) and a photo-detector measures the light that passes through the sample. Some of the ultraviolet light will pass through and some will be absorbed by the DNA / RNA. The more light absorbed by the sample, the higher the nucleic acid concentration in the sample. The resulting effect is that less light will strike the photodetector and this will produce a higher optical density (OD)
Using the Beer–Lambert law it is possible to relate the amount of light absorbed to the concentration of the absorbing molecule. At a wavelength of 260 nm, the average extinction coefficient for double-stranded DNA is 0.020 (μg/ml) cm, for single-stranded DNA it is 0.027 (μg/ml) cm, for single-stranded RNA it is 0.025 (μg/ml) cm and for short single-stranded oligonucleotides it is dependent on the length and base composition. Thus, an Absorbance (A) of 1 corresponds to a concentration of 50 μg/ml for double-stranded DNA. This method of calculation is valid for up to an A of at least 2. A more accurate extinction coefficient may be needed for oligonucleotides; these can be predicted using the nearest-neighbor model. | 0 | Theoretical and Fundamental Chemistry |
Equilibrium thermodynamics is the study of transfers of matter and energy in systems or bodies that, by agencies in their surroundings, can be driven from one state of thermodynamic equilibrium to another. The term thermodynamic equilibrium indicates a state of balance, in which all macroscopic flows are zero; in the case of the simplest systems or bodies, their intensive properties are homogeneous, and their pressures are perpendicular to their boundaries. In an equilibrium state there are no unbalanced potentials, or driving forces, between macroscopically distinct parts of the system. A central aim in equilibrium thermodynamics is: given a system in a well-defined initial equilibrium state, and given its surroundings, and given its constitutive walls, to calculate what will be the final equilibrium state of the system after a specified thermodynamic operation has changed its walls or surroundings. | 0 | Theoretical and Fundamental Chemistry |
The pyrimidine ring system has wide occurrence in nature
as substituted and ring fused compounds and derivatives, including the nucleotides cytosine, thymine and uracil, thiamine (vitamin B1) and alloxan. It is also found in many synthetic compounds such as barbiturates and the HIV drug zidovudine. Although pyrimidine derivatives such as alloxan were known in the early 19th century, a laboratory synthesis of a pyrimidine was not carried out until 1879, when Grimaux reported the preparation of barbituric acid from urea and malonic acid in the presence of phosphorus oxychloride.
The systematic study of pyrimidines began in 1884 with Pinner,
who synthesized derivatives by condensing ethyl acetoacetate with amidines. Pinner first proposed the name “pyrimidin” in 1885. The parent compound was first prepared by Gabriel and Colman in 1900,
by conversion of barbituric acid to 2,4,6-trichloropyrimidine followed by reduction using zinc dust in hot water. | 1 | Applied and Interdisciplinary Chemistry |
A metabotropic receptor, also referred to by the broader term G-protein-coupled receptor, is a type of membrane receptor that initiates a number of metabolic steps to modulate cell activity. The nervous system utilizes two types of receptors: metabotropic and ionotropic receptors. While ionotropic receptors form an ion channel pore, metabotropic receptors are indirectly linked with ion channels through signal transduction mechanisms, such as G proteins.
Both receptor types are activated by specific chemical ligands. When an ionotropic receptor is activated, it opens a channel that allows ions such as Na, K, or Cl to flow. In contrast, when a metabotropic receptor is activated, a series of intracellular events are triggered that can also result in ion channels opening or other intracellular events, but involve a range of second messenger chemicals. | 1 | Applied and Interdisciplinary Chemistry |
Physalaemin is a tachykinin peptide obtained from the Physalaemus frog, closely related to substance P. Its structure was first elucidated in 1964.
Like all tachykinins, physalaemin is a sialagogue (increases salivation) and a potent vasodilator with hypotensive effects. | 1 | Applied and Interdisciplinary Chemistry |
Deep cycling involves the exchange of materials with the mantle. The deep water cycle involves exchange of water with the mantle, with water carried down by subducting oceanic plates and returning through volcanic activity, distinct from the water cycle process that occurs above and on the surface of Earth. Some of the water makes it all the way to the lower mantle and may even reach the outer core.
In the conventional view of the water cycle (also known as the hydrologic cycle), water moves between reservoirs in the atmosphere and Earth's surface or near-surface (including the ocean, rivers and lakes, glaciers and polar ice caps, the biosphere and groundwater). However, in addition to the surface cycle, water also plays an important role in geological processes reaching down into the crust and mantle. Water content in magma determines how explosive a volcanic eruption is; hot water is the main conduit for economically important minerals to concentrate in hydrothermal mineral deposits; and water plays an important role in the formation and migration of petroleum. Petroleum is a fossil fuel derived from ancient fossilized organic materials, such as zooplankton and algae.
Water is not just present as a separate phase in the ground. Seawater percolates into oceanic crust and hydrates igneous rocks such as olivine and pyroxene, transforming them into hydrous minerals such as serpentines, talc and brucite. In this form, water is carried down into the mantle. In the upper mantle, heat and pressure dehydrates these minerals, releasing much of it to the overlying mantle wedge, triggering the melting of rock that rises to form volcanic arcs. However, some of the "nominally anhydrous minerals" that are stable deeper in the mantle can store small concentrations of water in the form of hydroxyl (OH), and because they occupy large volumes of the Earth, they are capable of storing at least as much as the world's oceans.
The conventional view of the ocean's origin is that it was filled by outgassing from the mantle in the early Archean and the mantle has remained dehydrated ever since. However, subduction carries water down at a rate that would empty the ocean in 1–2 billion years. Despite this, changes in the global sea level over the past 3–4 billion years have only been a few hundred metres, much smaller than the average ocean depth of 4 kilometres. Thus, the fluxes of water into and out of the mantle are expected to be roughly balanced, and the water content of the mantle steady. Water carried into the mantle eventually returns to the surface in eruptions at mid-ocean ridges and hotspots. Estimates of the amount of water in the mantle range from to 4 times the water in the ocean.
The deep carbon cycle is the movement of carbon through the Earth's mantle and core.
It forms part of the carbon cycle and is intimately connected to the movement of carbon in the Earth's surface and atmosphere. By returning carbon to the deep Earth, it plays a critical role in maintaining the terrestrial conditions necessary for life to exist. Without it, carbon would accumulate in the atmosphere, reaching extremely high concentrations over long periods of time. | 0 | Theoretical and Fundamental Chemistry |
According to the Journal Citation Reports, the journal had an impact factor of 6.88 for 2021.
It is indexed in the following bibliographic databases:
* Cambridge Structural Database (Cambridge Crystallographic Data Centre)
* Chemical Abstracts Service/SciFinder (ACS)
* ChemWeb (ChemIndustry.com)
* Chimica Database (Elsevier)
* Current Contents: Physical, Chemical & Earth Sciences (Thomson Reuters)
* INSPEC (IET)
* Journal Citation Reports/Science Edition (Thomson Reuters)
* Nature Index (Springer Nature)
* PASCAL Database (INIST/CNRS)
* Science Citation Index (Thomson Reuters)
* Science Citation Index Expanded (Thomson Reuters)
* SCOPUS (Elsevier)
* VINITI (All-Russian Institute of Science & Technological Information)
* Web of Science (Thomson Reuters) | 0 | Theoretical and Fundamental Chemistry |
People who work at fluorochemical production plants and in manufacturing industries that use PFASs in the industrial process can be exposed to PFASs in the workplace. Much of what we know about PFASs exposure and health effects began with medical surveillance studies of workers exposed to PFASs at fluorochemical production facilities. These studies began in the 1940s and were conducted primarily at U.S. and European manufacturing sites. Between the 1940s and 2000s, thousands of workers exposed to PFASs participated in research studies that advanced scientific understanding of exposure pathways, toxicokinetic properties, and adverse health effects associated with exposure.
The first research study to report elevated organic fluorine levels in the blood of fluorochemical workers was published in 1980. It established inhalation as a potential route of occupational PFAS exposure by reporting measurable levels of organic fluorine in air samples at the facility. Workers at fluorochemical production facilities have higher levels of PFOA and PFOS in their blood than the general population. Serum PFOA levels in fluorochemical workers are generally below 20,000 ng/mL but have been reported as high as 100,000 ng/mL, whereas the mean PFOA concentration among non-occupationally exposed cohorts in the same time frame was 4.9 ng/mL. Among fluorochemical workers, those with direct contact with PFASs have higher PFAS concentrations in their blood than those with intermittent contact or no direct PFAS contact. Blood PFAS levels have been shown to decline when direct contact ceases. PFOA and PFOS levels have declined in U.S. and European fluorochemical workers due to improved facilities, increased usage of personal protective equipment, and the discontinuation of these chemicals from production. Occupational exposure to PFASs in manufacturing continues to be an active area of study in China with numerous investigations linking worker exposure to various PFASs. | 0 | Theoretical and Fundamental Chemistry |
Lactones contribute significantly to the flavor of fruit, and of unfermented and fermented dairy products, and are therefore used as flavors and fragrances. Some examples are γ-decalactone (4-decanolide), which has a characteristic peach flavor; δ-decalactone (5-decanolide), which has a creamy coconut/peach flavour; γ-dodecalactone (4-dodecanolide), which also has a coconut/fruity flavor, a description which also fits γ-octalactone (4-octanolide), although it also has a herbaceous character; γ-nonalactone, which has an intense coconut flavor of this series, despite not occurring in coconut, and γ-undecalactone.
Macrocyclic lactones (cyclopentadecanolide, 15-pentadec-11/12-enolide) have odors similar to macrocyclic ketones of animal origin (muscone, civetone), but they can be prepared more easily, for example, by depolymerization of the corresponding linear polyesters. Replacement of a methylene unit by oxygen barely affects the odor of these compounds, and oxalactones with 15 – 17-membered rings are produced in addition to cyclopentadecanolide (e. g., 12-oxa-16-hexadecanolide). | 0 | Theoretical and Fundamental Chemistry |
An additional use for the injector technology is in vacuum ejectors in continuous train braking systems, which were made compulsory in the UK by the Regulation of Railways Act 1889. A vacuum ejector uses steam pressure to draw air out of the vacuum pipe and reservoirs of continuous train brake. Steam locomotives, with a ready source of steam, found ejector technology ideal with its rugged simplicity and lack of moving parts. A steam locomotive usually has two ejectors: a large ejector for releasing the brakes when stationary and a small ejector for maintaining the vacuum against leaks. The exhaust from the ejectors is invariably directed to the smokebox, by which means it assists the blower in draughting the fire. The small ejector is sometimes replaced by a reciprocating pump driven from the crosshead because this is more economical of steam and is only required to operate when the train is moving.
Vacuum brakes have been superseded by air brakes in modern trains, which allow the use of smaller brake cylinders and/or higher braking force due to the greater difference from atmospheric pressure. | 1 | Applied and Interdisciplinary Chemistry |
Bioadhesives are natural polymeric materials that act as adhesives. The term is sometimes used more loosely to describe a glue formed synthetically from biological monomers such as sugars, or to mean a synthetic material designed to adhere to biological tissue.
Bioadhesives may consist of a variety of substances, but proteins and carbohydrates feature prominently. Proteins such as gelatin and carbohydrates such as starch have been used as general-purpose glues by man for many years, but typically their performance shortcomings have seen them replaced by synthetic alternatives. Highly effective adhesives found in the natural world are currently under investigation. For example, bioadhesives secreted by microbes and by marine molluscs and crustaceans are being researched with a view to biomimicry. Furthermore, thiolation of proteins and carbohydrates enables these polymers (thiomers) to covalently adhere especially to cysteine-rich subdomains of proteins such as keratins or mucus glycoproteins via disulfide bond formation. Thiolated chitosan and thiolated hyaluronic acid are used as bioadhesives in various medicinal products. | 1 | Applied and Interdisciplinary Chemistry |
Shikimate can be used to synthesise (6S)-6-fluoroshikimic acid, an antibiotic which inhibits the aromatic biosynthetic pathway. More specifically, glyphosate inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). "Roundup Ready" genetically modified crops overcome that inhibition. | 1 | Applied and Interdisciplinary Chemistry |
An industrial process control or simply process control in continuous production processes is a discipline that uses industrial control systems and control theory to achieve a production level of consistency, economy and safety which could not be achieved purely by human manual control. It is implemented widely in industries such as automotive, mining, dredging, oil refining, pulp and paper manufacturing, chemical processing and power generating plants.
There is a wide range of size, type and complexity, but it enables a small number of operators to manage complex processes to a high degree of consistency. The development of large industrial process control systems was instrumental in enabling the design of large high volume and complex processes, which could not be otherwise economically or safely operated.
The applications can range from controlling the temperature and level of a single process vessel, to a complete chemical processing plant with several thousand control loops. | 1 | Applied and Interdisciplinary Chemistry |
The expression of the enzyme in adrenocortical cells is regulated by the trophic hormone corticotropin (ACTH). | 1 | Applied and Interdisciplinary Chemistry |
Coenzyme F is a family of coenzymes involved in redox reactions in a number of bacteria and archaea. It is derived from coenzyme F (7,8-didemethyl-8-hydroxy-5-deazariboflavin) and differs by having a oligoglutamyl tail attached via a 2-phospho-L-lactate bridge. F is so named because it is a flavin derivative with an absorption maximum at 420 nm.
F was originally discovered in methanogenic archaea and in Actinomycetota (especially in Mycobacterium). It is now known to be used also by Cyanobacteria and by soil Proteobacteria, Chloroflexi and Firmicutes. Eukaryotes including the fruit fly Drosophila melanogaster and the algae Ostreococcus tauri also use Coenzyme F.
F is structurally similar to FMN, but catalytically it is similar to NAD and NADP: it has low redox potential and always transfer a hydride. As a result, it is not only a versatile cofactor in biochemical reactions, but also being eyed for potential as an industrial catalyst. Similar to FMN, it has two states: one reduced state, notated as F-H, and one oxidized state, written as just F. F has largely similar redox properties, but cannot carry an electric charge and as a result probably slowly leaks out of the cellular membrane.
A number of F molecules, differing by the length of the oligoglutamyl tail, are possible; F-2, for example, refers to the version with two glutamyl units attached. Lengths from 4 to 9 are typical. | 1 | Applied and Interdisciplinary Chemistry |
Since carbon dioxide and oxygen compete at the active site of RuBisCO, carbon fixation by RuBisCO can be enhanced by increasing the carbon dioxide level in the compartment containing RuBisCO (chloroplast stroma). Several times during the evolution of plants, mechanisms have evolved for increasing the level of carbon dioxide in the stroma (see carbon fixation). The use of oxygen as a substrate appears to be a puzzling process, since it seems to throw away captured energy. However, it may be a mechanism for preventing carbohydrate overload during periods of high light flux. This weakness in the enzyme is the cause of photorespiration, such that healthy leaves in bright light may have zero net carbon fixation when the ratio of O to available to RuBisCO shifts too far towards oxygen. This phenomenon is primarily temperature-dependent: high temperatures can decrease the concentration of dissolved in the moisture of leaf tissues. This phenomenon is also related to water stress: since plant leaves are evaporatively cooled, limited water causes high leaf temperatures. plants use the enzyme PEP carboxylase initially, which has a higher affinity for . The process first makes a 4-carbon intermediate compound, hence the name plants, which is shuttled into a site of photosynthesis then decarboxylated, releasing to boost the concentration of .
Crassulacean acid metabolism (CAM) plants keep their stomata closed during the day, which conserves water but prevents the light-independent reactions (a.k.a. the Calvin Cycle) from taking place, since these reactions require to pass by gas exchange through these openings. Evaporation through the upper side of a leaf is prevented by a layer of wax. | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, Berman flow is a steady flow created inside a rectangular channel with two equally porous walls. The concept is named after a scientist Abraham S. Berman who formulated the problem in 1953. | 1 | Applied and Interdisciplinary Chemistry |
* High-pressure vessel: Vessel in which the diamond anvil cell is loaded.
* Clamp device seals the DAC; which is tightened by closure mechanism with motor driven screws.
* PLC (programmable logic controller): Controls air flow to the compressor and all valves. The PLC ensures that valves are opened and closed in the correct sequence for accurate loading and safety.
* Compressor: Responsible for compression of the gas. The compressor employs a dual-stage air-driven diaphragm design that creates pressure and avoids contamination. Able to achieve 207 MPa of pressure.
* Valves: Valves open and close via the PLC to regulate which gases enter the high-pressure vessel.
* Burst disks: Two burst disks in the system – one for the high-pressure system and one for the low-pressure system. These disks act as a pressure relief system that protects the system from over-pressurization
* Pressure transducers: A pressure sensor for the low- and high-pressure systems. Produces a 0–5 V output over their pressure range.
* Pressure meters: Digital displays connected to each pressure transducer and the PLC system.
* Vacuum pump and gauges: Cleans the system (by evacuation) before loading.
* Optical system: Used visual observation; allowing in situ observations of gasket deformation.
* Ruby fluorescence system: Pressure in the sample chamber can be measured during loading using an online ruby fluorescence system. Not all systems have an online ruby fluorescence system for in situ measuring. However, being able to monitor the pressure within the chamber while the DAC is being sealed is advantageous – ensuring the desired pressure is reached (or not over-shot). Pressure is measured by the shift in the laser induced luminescence of rubies in the sample chamber. | 0 | Theoretical and Fundamental Chemistry |
Differential capacitance in physics, electronics, and electrochemistry is a measure of the voltage-dependent capacitance of a nonlinear capacitor, such as an electrical double layer or a semiconductor diode. It is defined as the derivative of charge with respect to potential. | 0 | Theoretical and Fundamental Chemistry |
Ajivika is a "Nastika" school of thought whose metaphysics included a theory of atoms or atomism which was later adapted in the Vaiśeṣika school, which postulated that all objects in the physical universe are reducible to paramāṇu (atoms), and ones experiences are derived from the interplay of substance (a function of atoms, their number and their spatial arrangements), quality, activity, commonness, particularity and inherence. Everything was composed of atoms, qualities emerged from aggregates of atoms, but the aggregation and nature of these atoms was predetermined by cosmic forces. The school founders traditional name Kanada means atom eater, and he is known for developing the foundations of an atomistic approach to physics and philosophy in the Sanskrit text Vaiśeṣika Sūtra. His text is also known as Kanada Sutras, or Aphorisms of Kanada. | 1 | Applied and Interdisciplinary Chemistry |
Starting from the assumption that two wetted surfaces will stick together, e.g. the bottom of a glass cup on a wet counter top, will help to explain the idea of how capillary condensation causes two surfaces to bridge together. When looking at the Kelvin equation, where relative humidity comes into play, condensation that occurs below P will cause adhesion. However it is most often ignored that the adhesive force is dependent only on the particle radius (for wettable, spherical particles, at least) and therefore independent of the relative vapor pressure or humidity, within very wide limits. This is a consequence of the fact that particle surfaces are not smooth on the molecular scale, therefore condensation only occurs about the scattered points of actual contacts between the two spheres. Experimentally, however it is seen that capillary condensation plays a large role in bridging or adhering multiple surfaces or particles together. This can be important in the adhesion of dust and powders. It is important to note the difference between bridging and adhesion. While both are a consequence of capillary condensation, adhesion implies that the two particles or surfaces will not be able to separate without a large amount of force applied, or complete integration, as in sintering; bridging implies the formation of a meniscus that brings two surfaces or particles in contact with each other without direct integration or loss of individuality. | 1 | Applied and Interdisciplinary Chemistry |
Signal transduction is realized by activation of specific receptors and consequent production/delivery of second messengers, such as Ca or cAMP. These molecules operate as signal transducers, triggering intracellular cascades and in turn amplifying the initial signal.
Two main signal transduction mechanisms have been identified, via nuclear receptors, or via transmembrane receptors. In the first one, first messenger cross through the cell membrane, binding and activating intracellular receptors localized at nucleus or cytosol, which then act as transcriptional factors regulating directly gene expression. This is possible due to the lipophilic nature of those ligands, mainly hormones. In the signal transduction via transmembrane receptors, the first messenger binds to the extracellular domain of transmembrane receptor, activating it. These receptors may have intrinsic catalytic activity or may be coupled to effector enzymes, or may also be associated to ionic channels. Therefore, there are four main transmembrane receptor types: G protein coupled receptors (GPCRs), tyrosine kinase receptors (RTKs), serine/threonine kinase receptors (RSTKs), and ligand-gated ion channels (LGICs).
Second messengers can be classified into three classes:
# Hydrophilic/cytosolic – are soluble in water and are localized at the cytosol, including cAMP, cGMP, IP3, Ca, cADPR and S1P. Their main targets are protein kinases as PKA and PKG, being then involved in phosphorylation mediated responses.
# Hydrophobic/membrane-associated – are insoluble in water and membrane-associated, being localized at intermembrane spaces, where they can bind to membrane-associated effector proteins. Examples: PIP3, DAG, phosphatidic acid, arachidonic acid and ceramide. They are involved in regulation of kinases and phosphatases, G protein associated factors and transcriptional factors.
# Gaseous – can be widespread through cell membrane and cytosol, including nitric oxide and carbon monoxide. Both of them can activate cGMP and, besides of being capable of mediating independent activities, they also can operate in a coordinated mode. | 0 | Theoretical and Fundamental Chemistry |
Ammonium is oxidized to nitrate under aerobic conditions
:NH + 2O → NO + HO + 2H
Ammonium oxidation can be treated as part of BOD, so that BOD = CBOD + NBOD, where CBOD is the carbonaceous biochemical oxygen demand and NBOD is nitrogenous BOD. Usually CBOD is much higher than the ammonium concentration and thus NBOD often does not need to be considered. The change in oxygen deficit due to oxidation of ammonium is described as
where
* D is the saturation deficit.
* is the nitrification rate .
* is ammonium-nitrogen concentration.
The range of is typically 0.05-0.5 . | 1 | Applied and Interdisciplinary Chemistry |
Internal oxidation, in corrosion of metals, is the process of formation of corrosion products (e.g. a metal oxide) within the metal bulk. In other words, the corrosion products are created away from the metal surface, and they are isolated from the surface.
Internal oxidation occurs when some components of the alloy are oxidized in preference to the balance of the bulk. The oxidizer is often oxygen diffusing through the metal bulk from the interface, but it can be also another element (for example sulfur or nitrogen).
Internal oxidation is a well-known corrosion mechanism of nickel-based alloys in the temperature range of 500 to 1200 °C.
Internal oxidation is distinct from selective leaching. | 1 | Applied and Interdisciplinary Chemistry |
When looking at what affects SVA, one of the main things that come up first is the solvent that is used, and what nanostructure is wanted to be obtained. For example, if a hierarchical structure is desired, a solvent that has a vapor that can selectively mobilize the amorphous polymer chains of a semi-crystalline polymer is ideal because it can also keep the integrity of the crystals, allowing for the secondary structure to form.
Looking more at BCP itself, they make ordered nanostructures because of thermodynamic differences between different blocks of the polymer. The sample morphology at equilibrium can be predicted using the molar mass of the blocks, the degree of polymerization of the chains (N), and the Flory-Huggins interaction parameter (χ) which is a magnitude of exactly how incompatible the different blocks are. These factors, along with the composition of the BCP, allow microphase separation of chains and the rearrangement into the desired product. The composition provides an especially important part of the process as knowing the ordering, such as alternating AB monomers, gives light on how to section the polymer in the desired manner.
Along with this, the selection of a specific type of block polymer is important for the process and its effectiveness. The main thing to consider is the original structure of the block at room temperature, as well as, temperatures in which each block will begin to change phase. Knowing these temperatures is critical in determining when each will begin to react and take in solvent and at what rate this will happen, which is critical in pushing to a desired morphology of the given block polymer through annealing.
Other factors that affect SVA are parameters such as vapor pressure, solvent concertation in the film, and evaporation rate of the solvent. Each of these factors contributes to the volatility and imprecision at times of this method, not possessing a set mechanism for the construction of structures that are desired, such as nanocylinders. Getting perfect success of the desired morphology of a polymer has yet to be achieved with these plethoras of factors dictating formation. | 0 | Theoretical and Fundamental Chemistry |
Fatta-Kassinos received a Diploma in Chemical Engineering from the National Technical University of Athens (NTUA), Greece, in 1993, and completed a M.Sc. in Environmental Management and Education in 1995 from the European Association of Environmental Management and Education (EAEME). She then received her Ph.D. in Chemical Engineering in 1999 from NTUA. Her dissertation was titled "Development of a methodology for the estimation of the pollution level of the groundwater aquifers in the vicinity of waste disposal sites." Following this, she served as a Postdoctoral researcher for three years at NTUA between 1999 and 2003. | 1 | Applied and Interdisciplinary Chemistry |
Magnetic nanoparticles do not aggregate easily once the magnet is removed, and therefore are unlikely to block capillaries or cause thrombosis. In addition, iron oxide is biodegradable, and the iron can be reused in hemoglobin or iron metabolism pathways. | 1 | Applied and Interdisciplinary Chemistry |
Media filters are used to protect water quality in streams, rivers, and lakes. They can be effective at removing pollutants in stormwater such as suspended solids and phosphorus. Sand is the most common filter material. In other filters, sometimes called "organic filters," wood chips or leaf mold may be used. | 1 | Applied and Interdisciplinary Chemistry |
LEIS systems consist of the following:
# Ion Gun, used to direct a beam of ions at a target sample. An electron ionization ion source is typically used to ionize noble gas atoms such as He, Ne or Ar, while heating of wafers containing alkali atoms is used to create an alkali ion beam. The ions thus created hold a positive charge, typically +1, due to the ejection of electrons from the atoms. The range of energies used most often in LEIS is 500 eV to 20 keV. In order to attain good experimental resolution it is important to have a narrow energy spread (ΔE/E < 1%) in the outgoing ion beam.
# Ion beam manipulator, includes the electrostatic lenses of the ion gun for focusing and beam-chopping. Lenses consist of a series of either plate or cylinder geometries and serve to collimate the beam as well as to selectively filter the beam based on mass and velocity. Beam chopping is performed using a pulsed-wave generator when time-of-flight (TOF) experiments are performed. Ions only pass through the chopper when there is no applied voltage.
# Sample manipulator, allows an operator to change the position and/or angle of the target in order to perform experiments with varying geometries. Using directional controls, azimuthal (rotational) and incident angle adjustments may be made.
# Drift tube/drift region, used in TOF setup. TOF measurements are used when analysis of particle velocity is required. By pulsing ions towards the sample with a regular frequency, and observing the time to travel a certain distance after surface impact to a detector, it is possible to calculate the velocity of ions and neutrals coming from the surface. An accelerator may also be used in this setup, prior to the drift tube, in order to achieve separation of ions from neutrals when desired.
# Detector/electrostatic analyzer, used to detect the velocities and/or energies of scattered particles including ions and, in some cases, neutral species. As opposed to TOF analyzers, electrostatic analyzers achieve ion energy resolution using electrostatic deflectors to direct only ions of a particular energy range into a collector, while all other ions are redirected. This type of analyzer can give good energy resolution (and thus, selectivity) but typically suffers from poor sensitivity due to the fact that it only detects ions of a certain energy range and ignores neutral species altogether. Two types of detectors are used: channel electron multiplier (CEM) and microchannel plate (MCP) detectors. CEMs operate in a similar manner to photomultipliers, displaying a cascade of secondary electron emission processes initiated by ion or fast neutral (energy > 1 keV) impact to give a gain in signal current. In this way it is possible to efficiently detect even small ion or neutral particle fluxes. MCP detectors are essentially 2-dimensional arrays of CEMs, and they allow additional information about particle position to be obtained at the cost of sensitivity at any given position.
# Vacuum pumps; Studies are performed in ultra-high vacuum (UHV) conditions ( torr) in order to prevent unwanted interference with the ion beam and/or sample. Common UHV pumps include turbomolecular and ion pumps, with roughing pumping typically performed using a rotary vane pump. Due to the extreme surface (i.e. first-layer) sensitivity of LEIS, samples also need to be rigorously cleaned prior to analysis. Some common processes used to clean samples include sputtering and annealing. Appropriate equipment for cleaning must be contained within the vacuum chamber.
# Other analysis tools; in many cases it is desirable to perform multiple types of analysis on a sample within the same UHV system, or even at the same time. Some additional tools may include Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and x-ray photoelectron spectroscopy (XPS). Use of these tools typically requires the presence of additional detectors as well as electron and/or x-ray sources where applicable. | 0 | Theoretical and Fundamental Chemistry |
A raised weight accumulator consists of a vertical cylinder containing fluid connected to the hydraulic line. The cylinder is closed by a piston on which a series of weights are placed that exert a downward force on the piston and thereby pressurizes the fluid in the cylinder. In contrast to compressed gas and spring accumulators, this type delivers a nearly constant pressure, regardless of the volume of fluid in the cylinder, until it is empty. (The pressure will decline somewhat as the cylinder is emptied due to the decline in weight of the remaining fluid.)
A working example of this type of accumulator may be found at the hydraulic engine house, Bristol Harbour. The original 1887 accumulator is in place in its tower, an external accumulator was added in 1954 and this system was used until 2010 to power the Cumberland Basin (Bristol) lock gates. The water is pumped from the harbour into a header tank and then fed by gravity to the pumps. The working pressure is 750 psi (5.2 MPa, or 52 bar) which was used to power the cranes, bridges and locks of Bristol Harbour.
The original operating mechanism of Tower Bridge, London, also used this type of accumulator. Although no longer in use, two of the six accumulators may still be seen in situ in the bridge's museum.
Regents Canal Dock, now named Limehouse Basin has the remains of a hydraulic accumulator, dating from 1869, a fragment of the oldest remaining such facility in the world, the second at the dock, which was installed later than that at Poplar Dock, originally listed incorrectly as a signalbox for the London and Blackwall Railway, when correctly identified, it was restored as a tourist attraction by the now defunct London Docklands Development Corporation. Now owned by the Canal & River Trust, it is open for large groups on application to the Dockmasters Office at the basin and on both the afternoons of London Open House Weekend, held on the third weekend of September each year.
London had an extensive public hydraulic power system from the mid-nineteenth century finally closing in the 1970s with 5 hydraulic power stations, operated by the London Hydraulic Power Company. Railway goods yards and docks often had their own separate system. | 1 | Applied and Interdisciplinary Chemistry |
In April of 2022, Pfizer voluntarily recalled five batches of the drug because of the presence of a nitrosamine, NNitroso-quinapril. Testing found that the amount of nitrosamines was above the acceptable daily intake level (all humans are exposed to nitrosamines up to a certain daily level by cured and grilled meats, water, dairy products, and vegetables) set by the U.S.'s Food and Drug Administration (FDA). Though long-term ingestion of NNitroso-quinapril potentially might cause cancer in some individuals, there is not believed to be an imminent risk of harm. | 0 | Theoretical and Fundamental Chemistry |
Hexaammineplatinum(IV) chloride is the chemical compound with the formula [Pt(NH)]Cl. It is the chloride salt of the metal ammine complex [Pt(NH)]. The cation features six ammonia (called ammines in coordination chemistry) ligands attached to the platinum(IV) ion. It is a white, water soluble solid. | 0 | Theoretical and Fundamental Chemistry |
Recyclability is a key factor of a sustainable material. It reduces the need to mine new resources and requires less energy than mining. Copper and its alloys are virtually 100% recyclable and can be recycled infinitely without any loss of quality (i.e., copper does not degrade (i.e., downcycle) after each recycling loop as do most non-metallic materials, if they are recyclable at all). Copper retains much of its primary metal value: premium-grade scrap normally contains at least 95% of the value of primary metal from newly mined ore. Scrap values for competing materials range from about 60% down to 0%. And copper recycling requires only around 20% of the energy needed to extract and process primary metal.
Currently, around 40% of Europe's annual copper demand and about 55% of copper used in architecture come from recycled sources. New copper coil and sheet often have 75%-100% recycled content.
By 1985, more copper was recycled than the total amount of copper that was consumed in 1950. This is due to the relative ease of reusing processing waste and salvaging copper from products after their useful life. | 1 | Applied and Interdisciplinary Chemistry |
In the late 1990s, the World Trade Organization authorized the United States and Canada to impose retaliatory tariffs of US$116.8 million per year on the European Union after it found the EU beef hormone ban to be in violation of the WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement). In September 2009, the trade representatives from the US and EU signed a memorandum of understanding, which established a new duty-free import quota in the European Union for grain-fed, high-quality beef as part of a compromise solution. | 0 | Theoretical and Fundamental Chemistry |
Various magnetometers use NMR effects to measure magnetic fields, including proton precession magnetometers (PPM) (also known as proton magnetometers), and Overhauser magnetometers. | 0 | Theoretical and Fundamental Chemistry |
The spin precession of an electron in an external electromagnetic field is described by the Bargmann–Michel–Telegdi (BMT) equation
where , , , and are polarization four-vector, charge, mass, and magnetic moment, is four-velocity of electron (in a system of units in which ), , , and is electromagnetic field-strength tensor. Using equations of motion,
one can rewrite the first term on the right side of the BMT equation as , where is four-acceleration. This term describes Fermi–Walker transport and leads to Thomas precession. The second term is associated with Larmor precession.
When electromagnetic fields are uniform in space or when gradient forces like can be neglected, the particle's translational motion is described by
The BMT equation is then written as
The Beam-Optical version of the Thomas-BMT, from the Quantum Theory of Charged-Particle Beam Optics, applicable in accelerator optics | 0 | Theoretical and Fundamental Chemistry |
Particles will, in effect, "stick" to the surface of an object moving through it. This layer of particles is called the boundary layer. At the surface of the object, it is essentially static due to the friction of the surface. The object, with its boundary layer is effectively the new shape of the object that the rest of the molecules "see" as the object approaches. This boundary layer can separate from the surface, essentially creating a new surface and completely changing the flow path. The classical example of this is a stalling airfoil. The delta wing image clearly shows the boundary layer thickening as the gas flows from right to left along the leading edge. | 0 | Theoretical and Fundamental Chemistry |
Sulfur bloom refers to the migration of sulfur, usually as S, to the surface of a rubber article either before or after vulcanization. Blooming is undesirable in rubber processing. When sulfur bloom appears before vulcanization, the rubber is deprived of the crosslinking agent. Sulfur bloom after vulcanization indicates incomplete vulcanization. In rubber processing, ingredients other than sulfur can "bloom", including antioxidants, fatty acids, and accelerators. | 0 | Theoretical and Fundamental Chemistry |
Surface chemistry of implantable electrodes proves to be more of a design concern for chronically implanted electrodes as compared to those with only acute implantation times. For acute implantations, the main concerns are laceration damage and degradation of particles left behind after electrode removal. For chronically implanted electrodes the cellular response and tissue encapsulation of the foreign body, regardless of degradation – even for materials that are highly biocompatible – are the primary concerns. Degradation, however, is still undesirable because particles can be toxic to tissue, can spread throughout the body, and even trigger an allergic response. Surface chemistry is an area of science applicable to biological implants. Bulk material properties are important when considering applications, however, it is the materials' surface (top several layers of molecules) that determines the biological response and is therefore the key to implant success. Implants within the central nervous system are unique in their manor of cellular response; there is little room for error. Prosthesis in these areas are typically electrodes or electrode arrays. | 0 | Theoretical and Fundamental Chemistry |
Returning home, she became more involved with the opposition to the dictator Fulgencio Batista. A meeting with revolutionary leader Frank País led her to become a leader of the revolutionary movement in Oriente province. Espín met the Castro brothers who had relocated to Mexico after their failed armed attack on the Moncada Barracks in July 1953 and release from prison in 1955. Espin acted as a messenger between the Julio 26 Movement in Mexico and Pais back in Cuba. She then went on to assist the revolutionaries in the Sierra Maestra mountains after the 26th of July Movement's return to Cuba on the Granma yacht in November 1956.
Espíns ability to speak both Spanish and English allowed her to represent the revolutionary movement on an international scale. Pepín Bosch, an executive of the Bacardi Corporation, arranged a meeting between CIA Inspector General Lyman Kirkpatrick and representatives of the 26th of July Movement in 1957. Espín, as both a revolutionary leader and the daughter of a Bacardi executive, told Kirkpatrick that the revolutionaries only wanted "what you Americans have: clean politics and a clean police system." She also acted as an interpreter for an interview between New York Times reporter Herbert Matthews and Fidel Castro in 1957, which served the dual purpose of spreading news of the revolution and assuring Cubans and the international community that Batistas claims of Castro's death were false. | 1 | Applied and Interdisciplinary Chemistry |
Sometimes modulation of transgene expression may be necessary since strong constitutive expression of a therapeutic gene in retinal tissues could be deleterious for long-term retinal function. Different methods have been utilized for the expression modulation. One way is using exogenously regulatable promoter system in AAV vectors. For example, the tetracycline-inducible expression system uses a silencer/transactivator AAV2 vector and a separate inducible doxycycline-responsive coinjection. When induction occurs by oral doxycycline, this system shows tight regulation of gene expression in both photoreceptor and RPE cells. | 1 | Applied and Interdisciplinary Chemistry |
Outdoor air may contain low levels of benzene from automobile service stations, wood smoke, tobacco smoke, the transfer of gasoline, exhaust from motor vehicles, and industrial emissions. About 50% of the entire nationwide (United States) exposure to benzene results from smoking tobacco or from exposure to tobacco smoke. After smoking 32 cigarettes per day, the smoker would take in about 1.8 milligrams (mg) of benzene. This amount is about 10 times the average daily intake of benzene by nonsmokers.
Inhaled benzene is primarily expelled unchanged through exhalation. In a human study 16.4 to 41.6% of retained benzene was eliminated through the lungs within five to seven hours after a two- to three-hour exposure to 47 to 110 ppm and only 0.07 to 0.2% of the remaining benzene was excreted unchanged in the urine. After exposure to 63 to 405 mg/m of benzene for 1 to 5 hours, 51 to 87% was excreted in the urine as phenol over a period of 23 to 50 hours. In another human study, 30% of absorbed dermally applied benzene, which is primarily metabolized in the liver, was excreted as phenol in the urine. | 1 | Applied and Interdisciplinary Chemistry |
The blast furnace remains an important part of modern iron production. Modern furnaces are highly efficient, including Cowper stoves to pre-heat the blast air and employ recovery systems to extract the heat from the hot gases exiting the furnace. Competition in industry drives higher production rates. The largest blast furnace in the world is in South Korea, with a volume around . It can produce around of iron per year.
This is a great increase from the typical 18th-century furnaces, which averaged about per year. Variations of the blast furnace, such as the Swedish electric blast furnace, have been developed in countries which have no native coal resources.
According to Global Energy Monitor, the blast furnace is likely to become obsolete to meet climate change objectives of reducing carbon dioxide emission, but BHP disagrees. An alternative process involving direct reduced iron is likely to succeed it, but this also needs to use a blast furnace to melt the iron and remove the gangue (impurities) unless the ore is very high quality. | 1 | Applied and Interdisciplinary Chemistry |
Purine metabolism refers to the metabolic pathways to synthesize and break down purines that are present in many organisms. | 1 | Applied and Interdisciplinary Chemistry |
tert-Butyllithium is a chemical compound with the formula (CH)CLi. As an organolithium compound, it has applications in organic synthesis since it is a strong base, capable of deprotonating many carbon molecules, including benzene. tert-Butyllithium is available commercially as solutions in hydrocarbons (such as pentane); it is not usually prepared in the laboratory. | 0 | Theoretical and Fundamental Chemistry |
Normal air comprises in crude numbers 80 percent nitrogen and 20 percent oxygen . Both molecules are small and non-polar (and therefore non-associating). We can therefore expect that the behaviour of air within broad temperature and pressure ranges can be approximated as an ideal gas with reasonable accuracy. Experimental values for the compressibility factor confirm this.
values are calculated from values of pressure, volume (or density), and temperature in Vasserman, Kazavchinskii, and Rabinovich, "Thermophysical Properties of Air and Air Components;' Moscow, Nauka, 1966, and NBS-NSF Trans. TT 70-50095, 1971: and Vasserman and Rabinovich, "Thermophysical Properties of Liquid Air and Its Component, "Moscow, 1968, and NBS-NSF Trans. 69-55092, 1970. | 0 | Theoretical and Fundamental Chemistry |
An aromatic ring can assist in the formation of a carbocationic intermediate called a phenonium ion by delocalising the positive charge.
When the following tosylate reacts with acetic acid in solvolysis then rather than a simple S2 reaction forming B, a 48:48:4 mixture of A, B (which are enantiomers) and C+D was obtained .
The mechanism which forms A and B is shown below. | 0 | Theoretical and Fundamental Chemistry |
Tautomerization is pervasive in organic chemistry. It is typically associated with polar molecules and ions containing functional groups that are at least weakly acidic. Most common tautomers exist in pairs, which means that the hydrogen is located at one of two positions, and even more specifically the most common form involves a hydrogen changing places with a double bond: . Common tautomeric pairs include:
* ketone – enol: , see keto–enol tautomerism
* enamine – imine:
**cyanamide – carbodiimide
**guanidine – guanidine – guanidine: With a central carbon surrounded by three nitrogens, a guanidine group allows this transform in three possible orientations
* amide – imidic acid: (e.g., the latter is encountered during nitrile hydrolysis reactions)
**lactam – lactim, a cyclic form of amide-imidic acid tautomerism in 2-pyridone and derived structures such as the nucleobases guanine, thymine, and cytosine
* imine – imine, e.g., during pyridoxal phosphate catalyzed enzymatic reactions
*nitro – aci-nitro (nitronic acid):
* nitroso – oxime:
* ketene – ynol, which involves a triple bond:
* amino acid – ammonium carboxylate, which applies to the building blocks of the proteins. This shifts the proton more than two atoms away, producing a zwitterion rather than shifting a double bond:
*phosphite – phosphonate: between trivalent and pentavalent phosphorus. | 0 | Theoretical and Fundamental Chemistry |
Research aimed at engineered resistance follows multiple strategies. One is to transfer useful PRRs into species that lack them. Identification of functional PRRs and their transfer to a recipient species that lacks an orthologous receptor could provide a general pathway to additional broadened PRR repertoires. For example, the Arabidopsis PRR EF-Tu receptor (EFR) recognizes the bacterial translation elongation factor EF-Tu. Research performed at Sainsbury Laboratory demonstrated that deployment of EFR into either Nicotiana benthamianaor Solanum lycopersicum (tomato), which cannot recognize EF-Tu, conferred resistance to a wide range of bacterial pathogens. EFR expression in tomato was especially effective against the widespread and devastating soil bacterium Ralstonia solanacearum. Conversely, the tomato PRR Verticillium 1 (Ve1) gene can be transferred from tomato to Arabidopsis, where it confers resistance to race 1 Verticillium isolates. | 1 | Applied and Interdisciplinary Chemistry |
Stercobilin results from breakdown of the heme moiety of hemoglobin found in erythrocytes. Macrophages break down senescent erythrocytes and break the heme down into biliverdin, which rapidly reduces to free bilirubin. Bilirubin binds tightly to plasma proteins (especially albumin) in the blood stream and is transported to the liver, where it is conjugated with one or two glucuronic acid residues into bilirubin diglucuronide, and secreted into the small intestine as bile. In the small intestine, some bilirubin glucuronide is converted back to bilirubin via bacterial enzymes in the terminal ileum. This bilirubin is further converted to colorless urobilinogen. Urobilinogen that remains in the colon can either be reduced to stercobilinogen and finally oxidized to stercobilin, or it can be directly reduced to stercobilin. Stercobilin is responsible for the brown color of human feces. Stercobilin is then excreted in the feces. | 1 | Applied and Interdisciplinary Chemistry |
The protein encoded by this gene belongs to the immunoglobulin superfamily. It is a type I membrane protein. The protein may play a role in the adhesive interactions of activated T and NK cells during the late phase of the immune response. It may also function in antigen presentation. Alternative splicing generates multiple transcript variants encoding distinct isoforms. [provided by RefSeq, Jan 2016]. | 1 | Applied and Interdisciplinary Chemistry |
Selegiline has an oral bioavailability of about 10%, which increases when ingested together with a fatty meal, as the molecule is fat soluble. Selegiline and its metabolites bind extensively to plasma proteins (at a rate of 94%). They cross the blood–brain barrier and enter the brain, where they most concentrated at the thalamus, basal ganglia, midbrain, and cingulate gyrus.
Selegiline is mostly metabolized in the intestines and liver; it and its metabolites are excreted in the urine.
Buccal administration of selegiline results in 5-fold higher bioavailability, more reproducible blood concentration, and produces fewer amphetamine metabolites than the oral tablet form. | 0 | Theoretical and Fundamental Chemistry |
Grain strength generally follows the Hall–Petch relation, which states that material strength decreases with the square root of the grain size. A higher number of smaller subgrains leads to a higher yield stress, and so some materials may be purposefully manufactured to have many subgrains, and in this case subgrain rotation recrystallization should be avoided.
Precipitates may also form in grain boundaries. It has been observed that precipitates in subgrain boundaries grow in a more elongated shape parallel to the adjacent grains, whereas precipitates in HAGB are blockier. This difference in aspect ratio may provide different strengthening effects to the material; long plate-like precipitates in the LAGB may delaminate and cause brittle failure under stress. Subgrain rotation recrystallization reduces the number of LAGB, thus reducing the number of flat, long precipitates, and also reducing the number of available pathways for this brittle failure. | 1 | Applied and Interdisciplinary Chemistry |
Deuterium NMR is NMR spectroscopy of deuterium (H or D), an isotope of hydrogen.
Deuterium is an isotope with spin = 1, unlike hydrogen-1, which has spin = 1/2. The term deuteron NMR, in direct analogy to proton NMR, is also used. Deuterium NMR has a range of chemical shift similar to proton NMR but with poor resolution, due to the smaller magnitude of the magnetic dipole moment of the deuteron relative to the proton. It may be used to verify the effectiveness of deuteration: a deuterated compound will show a strong peak in deuterium NMR but not proton NMR.
Deuterium NMR spectra are especially informative in the solid state because of its relatively small quadrupole moment in comparison with those of bigger quadrupolar nuclei such as chlorine-35, for example. This allows for the whole spectrum to be excited with practically achievable pulses of a few microseconds in duration. However, since the natural abundance of H is only 0.016%, the sample must usually be isotope enriched with H to achieve a sufficiently strong signal. For a given C-D moiety, the quadrupolar splitting in the H NMR spectrum depends in a simple way on the angle between the C-D bond and the applied static magnetic field. Thus, H NMR can probe orientation distributions in partially ordered deuterated polymers. Changes in C-D bond orientation due to molecular motions have pronounced effects on the spectral line shape. One example is the use of deuterium NMR to study lipid membrane phase behavior. | 0 | Theoretical and Fundamental Chemistry |
Pletz grouped the explosophores into eight distinct categories.
;I.
:These represent:
:* the nitro group, a nitrogen atom bound to two oxygen atoms as well as an organic molecule (e.g. TNT, RDX)
:* the nitrate ion, a nitrogen atom bound to three oxygen atoms, (e.g. nitroglycerin, ANFO)
:* the nitrite ion, a nitrogen atom bound to two oxygen atoms
:Most commercially used explosives include the nitrate ion or the nitro group.
;II.
:The azo and azide groups respectively, connected to organic/inorganic compounds (e.g. silver azide , lead azide , ammonium azide )
;III.
:The halogenated nitrogen group X:halogen (e.g. nitrogen triiodide and nitrogen trichloride )
;IV.
:The fulminate group (e.g. fulminic acid HONC and mercury fulminate )
;V.
:The chlorate and perchlorate groups respectively, connected to organics/inorganics (e.g. potassium chlorate , fluorine perchlorate )
;VI.
:The peroxide and ozonide groups respectively, connected to organics/inorganics (e.g. acetone peroxide, butanone peroxide)
;VII.
:The acetylide group with its metal derivatives (e.g. silver acetylide , copper acetylide )
;VIII. A metal atom connected by an unstable bond to the carbon of certain organic radicals
:This class contains for instance organic compounds of mercury, thallium, and lead.
;Other
:Other substances have been characterised as explosophores outside of the eight classes as defined by Pletz. | 0 | Theoretical and Fundamental Chemistry |
In contrast to chemical cross-links, physical cross-links are formed by weaker interactions. For example, sodium alginate gels upon exposure to calcium ions, which form ionic bonds that bridge between alginate chains. Polyvinyl alcohol gels upon the addition of borax through hydrogen bonding between boric acid and the polymer's alcohol groups. Other examples of materials which form physically cross-linked gels include gelatin, collagen, agarose, and agar agar. | 0 | Theoretical and Fundamental Chemistry |
The equations for β decay are similar, with the generic equation
giving
However, in this equation, the electron masses do not cancel, and we are left with
Because the reaction will proceed only when the value is positive, β decay can occur when the mass of atom exceeds that of by at least twice the mass of the electron. | 0 | Theoretical and Fundamental Chemistry |
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for some minerals in 1997. Where there was not sufficient information to establish EARs and RDAs, an estimate designated Adequate Intake (AI) was used instead. AIs are typically matched to actual average consumption, with the assumption that there appears to be a need, and that need is met by what people consume. The current AI for women 19 years and older is 3.0 mg/day (includes pregnancy and lactation). The AI for men is 4.0 mg/day. The AI for children ages 1–18 increases from 0.7 to 3.0 mg/day. The major known risk of fluoride deficiency appears to be an increased risk of bacteria-caused tooth cavities. As for safety, the IOM sets tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of fluoride the UL is 10 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For women ages 18 and older the AI is set at 2.9 mg/day (includes pregnancy and lactation). For men the value is 3.4 mg/day. For children ages 1–17 years the AIs increase with age from 0.6 to 3.2 mg/day. These AIs are comparable to the U.S. AIs. The EFSA reviewed safety evidence and set an adult UL at 7.0 mg/day (lower for children).
For U.S. food and dietary supplement labeling purposes the amount of a vitamin or mineral in a serving is expressed as a percent of Daily Value (%DV). Although there is information to set Adequate Intake, fluoride does not have a Daily Value and is not required to be shown on food labels. | 1 | Applied and Interdisciplinary Chemistry |
Cyanobacteria (), also called Cyanobacteriota or Cyanophyta, are a phylum of autotrophic gram-negative bacteria that can obtain biological energy via photosynthesis. The name cyanobacteria refers to their color (), which similarly forms the basis of cyanobacteria's common name, blue-green algae, although they are not scientifically classified as algae. They appear to have originated in a freshwater or terrestrial environment.
Cyanobacteria are probably the most numerous taxon to have ever existed on Earth and the first organisms known to have produced oxygen. By producing and releasing oxygen as a byproduct of photosynthesis, cyanobacteria are thought to have converted the early oxygen-poor, reducing atmosphere into an oxidizing one, causing the Great Oxidation Event and the "rusting of the Earth", which dramatically changed the composition of life forms on Earth.
Cyanobacteria use photosynthetic pigments, such as various forms of chlorophyll, carotenoids, phycobilins to convert the energy in sunlight to chemical energy. Unlike heterotrophic prokaryotes, cyanobacteria have internal membranes. These are flattened sacs called thylakoids where photosynthesis is performed. Phototrophic eukaryotes such as green plants perform photosynthesis in plastids that are thought to have their ancestry in cyanobacteria, acquired long ago via a process called endosymbiosis. These endosymbiotic cyanobacteria in eukaryotes then evolved and differentiated into specialized organelles such as chloroplasts, chromoplasts, etioplasts, and leucoplasts, collectively known as plastids.
Sericytochromatia, the proposed name of the paraphyletic and most basal group, is the ancestor of both the non-photosynthetic group Melainabacteria and the photosynthetic cyanobacteria, also called Oxyphotobacteria.
The cyanobacteria Synechocystis and Cyanothece are important model organisms with potential applications in biotechnology for bioethanol production, food colorings, as a source of human and animal food, dietary supplements and raw materials. Cyanobacteria produce a range of toxins known as cyanotoxins that can cause harmful health effects in humans and animals. | 0 | Theoretical and Fundamental Chemistry |
In particle physics, deep inelastic scattering is the name given to a process used to probe the insides of hadrons (particularly the baryons, such as protons and neutrons), using electrons, muons and neutrinos. It was first attempted in the 1960s and 1970s and provided the first convincing evidence of the reality of quarks, which up until that point had been considered by many to be a purely mathematical phenomenon. It is an extension of Rutherford scattering to much higher energies of the scattering particle and thus to much finer resolution of the components of the nuclei.
Henry Way Kendall, Jerome Isaac Friedman and Richard E. Taylor were joint recipients of the Nobel Prize of 1990 "for their pioneering investigations concerning deep inelastic scattering of electrons on protons and bound neutrons, which have been of essential importance for the development of the quark model in particle physics." | 0 | Theoretical and Fundamental Chemistry |
The Dallol area lies up to below sea level, and has been repeatedly flooded in the past when waters from the Red Sea have flowed into the depression. The last separation from the Red Sea was about 30,000 years ago.
The discovery of the volcano by the first European settlers certainly dates from the first colonization and expeditions in the region, in the 17th or 18th century. But the hostility of the depression, the unbearable heat which reigns there, and the dangers of the site (acid basins, toxic fumes), did not favour the exploration of the zones close to the crater. On the contrary, the Erta Ale was much more accessible, especially because the part of the rift where it is located (called the Erta Ale Range), is significantly higher. The last eruption of this phreato-magmatic volcano dates back to 2011. | 0 | Theoretical and Fundamental Chemistry |
In polymer chemistry, a repeat unit or repeating unit (or mer) is a part of a polymer whose repetition would produce the complete polymer chain (except for the end-groups) by linking the repeat units together successively along the chain, like the beads of a necklace.
A repeat unit is sometimes called a mer (or mer unit). "Mer" originates from the Greek word meros, which means "a part". The word polymer derives its meaning from this, which means "many mers". A repeat unit (mer) is not to be confused with the term monomer, which refers to the small molecule from which a polymer is synthesized.
One of the simplest repeat units is that of the addition polymer polyvinyl chloride,
-[CH-CHCl]-, whose repeat unit is -[CH-CHCl]-.
In this case the repeat unit has the same atoms as the monomer vinyl chloride CH=CHCl. When the polymer is formed, the C=C double bond in the monomer is replaced by a C-C single bond in the polymer repeat unit, which links by two new bonds to adjoining repeat units.
In condensation polymers (see examples below), the repeat unit contains fewer atoms than the monomer or monomers from which it is formed.
The subscript "n" denotes the degree of polymerisation, that is, the number of units linked together. The molecular mass of the repeat unit, M, is simply the sum of the atomic masses of the atoms within the repeat unit. The molecular mass of the chain is just the product nM. Other than monodisperse polymers, there is normally a molar mass distribution caused by chains of different length.
In copolymers there are two or more types of repeat unit, which may be arranged in alternation, or at random, or in other more complex patterns. | 0 | Theoretical and Fundamental Chemistry |
Exothermic and endothermic describe two types of chemical reactions or systems found in nature, as follows: | 0 | Theoretical and Fundamental Chemistry |
A solute in dilute solution usually follows Henrys law rather than Raoults law, and it is more usual to express the composition of the solution in terms of the molar concentration (in mol/L) or the molality (in mol/kg) of the solute rather than in mole fractions. The standard state of a dilute solution is a hypothetical solution of concentration = 1 mol/L (or molality = 1 mol/kg) which shows ideal behaviour (also referred to as "infinite-dilution" behaviour). The standard state, and hence the activity, depends on which measure of composition is used. Molalities are often preferred as the volumes of non-ideal mixtures are not strictly additive and are also temperature-dependent: molalities do not depend on volume, whereas molar concentrations do.
The activity of the solute is given by: | 0 | Theoretical and Fundamental Chemistry |
The huge amount of Pre-Hispanic silver adornments known especially from Perú, Bolivia and Ecuador raises the question whether the pre-Hispanic civilizations obtained the raw material from native ores or from argentiferous-lead ores. Although native silver may be available in America, it is as rare as in the Old World. From colonial texts it is known that silver mines were open in colonial times by the Spaniards from Mexico to Argentina, the main ones being those of Tasco, Mexico, and Potosí in Bolivia.
Some kind of blast furnaces called huayrachinas were described in colonial texts, as native technology furnaces used in Perú and Bolivia to smelt the ores that come from the silver mines owned by the Spaniards. Although it is not conclusive, it is believed that these kinds of furnaces were used before the Spanish Conquest. Ethnoarchaeological and archaeological work in Porco Municipality, Potosí, Bolivia, has suggested pre-European use of huayrachinas.
There are no specific archaeological accounts about silver smelting or mining in the Andes prior to the Incas. Silver and lead artefacts have been found in the Peruvian central highlands dated in the pre-Inca and Inca periods. From the presence of lead in silver artefacts, archaeologists suggest that cupellation occurred there. | 1 | Applied and Interdisciplinary Chemistry |
Some thiosemicarbazones have medicinal properties, e.g. the antiviral metisazone and the antibiotic thioacetazone. Thiosemicarbazones are also widely used as ligands in coordination chemistry. The affinity of thiosemicarbazones for metal ions is exploited in controlling iron overload. | 0 | Theoretical and Fundamental Chemistry |
According to the complexity of the DNA encoded chemical library (typically between 10 and 10 members), a conventional Sanger sequencing based decoding is unlikely to be usable in practice, due both to the high cost per base for the sequencing and to the tedious procedure involved. High throughput sequencing technologies exploited strategies that parallelize the sequencing process displacing the use of capillary electrophoresis and producing thousands or millions of sequences at once. In 2008 was described the first implementation of a high-throughput sequencing technique originally developed for genome sequencing (i.e. "454 technology") to the fast and efficient decoding of a DNA encoded chemical library comprising 4000 compounds. This study led to the identification of novel chemical compounds with submicromolar dissociation constants towards streptavidin and definitely shown the feasibility to construct, perform selections and decode DNA-encoded libraries containing millions of chemical compounds. | 1 | Applied and Interdisciplinary Chemistry |
After leaching, the leach liquor must normally undergo concentration of the metal ions that are to be recovered. Additionally, undesirable metal ions sometimes require removal.
*Precipitation is the selective removal of a compound of the targeted metal or removal of a major impurity by precipitation of one of its compounds. Copper is precipitated as its sulfide as a means to purify nickel leachates.
*Cementation is the conversion of the metal ion to the metal by a redox reaction. A typical application involves addition of scrap iron to a solution of copper ions. Iron dissolves and copper metal is deposited.
*Solvent Extraction
*Ion exchange
*Gas reduction. Treating a solution of nickel and ammonia with hydrogen affords nickel metal as its powder.
*Electrowinning is a particularly selective if expensive electrolysis process applied to the isolation of precious metals. Gold can be electroplated from its solutions. | 1 | Applied and Interdisciplinary Chemistry |
The process of repolarization causes an overshoot in the potential of the cell. Potassium ions continue to move out of the axon so much so that the resting potential is exceeded and the new cell potential becomes more negative than the resting potential. The resting potential is ultimately re-established by the closing of all voltage-gated ion channels and the activity of the sodium potassium ion pump. | 0 | Theoretical and Fundamental Chemistry |
Severin Schwan, the CEO of the Swiss company Roche, reported that Roche's research and development costs amounted to $12.3 billion in 2018, a quarter of the entire National Institutes of Health budget. Given the profit-driven nature of pharmaceutical companies and their research and development expenses, companies use their research and development expenses as a starting point to determine appropriate yet profitable prices.
Pharmaceutical companies spend a large amount on research and development before a drug is released to the market and costs can be further divided into three major fields: the discovery into the drug’s specific medical field, clinical trials, and failed drugs. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, a moiety ( ) is a part of a molecule that is given a name because it is identified as a part of other molecules as well.
Typically, the term is used to describe the larger and characteristic parts of organic molecules, and it should not be used to describe or name smaller functional groups of atoms that chemically react in similar ways in most molecules that contain them. Occasionally, a moiety may contain smaller moieties and functional groups.
A moiety that acts as a branch extending from the backbone of a hydrocarbon molecule is called a substituent or side chain, which typically can be removed from the molecule and substituted with others.
The term is also used in pharmacology, where an active moiety is the part of a molecule responsible for the physiological or pharmacological action of a drug. | 0 | Theoretical and Fundamental Chemistry |
Compliance is the ability of lungs and thorax to expand.
Lung compliance is defined as the volume change per unit of pressure change across the lung. Measurements of lung volume obtained during the controlled inflation/deflation of a normal lung show that the volumes obtained during deflation exceed those during inflation, at a given pressure. This difference in inflation and deflation volumes at a given pressure is called hysteresis and is due to the air-water surface tension that occurs at the beginning of inflation. However, surfactant decreases the alveolar surface tension, as seen in cases of premature infants with infant respiratory distress syndrome. The normal surface tension for water is 70 dyn/cm (70 mN/m) and in the lungs, it is 25 dyn/cm (25 mN/m); however, at the end of the expiration, compressed surfactant phospholipid molecules decrease the surface tension to very low, near-zero levels. Pulmonary surfactant thus greatly reduces surface tension, increasing compliance allowing the lung to inflate much more easily, thereby reducing the work of breathing. It reduces the pressure difference needed to allow the lung to inflate. The lung's compliance, and ventilation decrease when lung tissue becomes diseased and fibrotic. | 0 | Theoretical and Fundamental Chemistry |
Hollywood is a RNA splicing database containing data for the splicing of orthologous genes in different species. | 1 | Applied and Interdisciplinary Chemistry |
According to the general definition, every element of the periodic table (except some noble gases) forms one or more hydrides. These substances have been classified into three main types according to the nature of their bonding:
*Ionic hydrides, which have significant ionic bonding character.
*Covalent hydrides, which include the hydrocarbons and many other compounds which covalently bond to hydrogen atoms.
*Interstitial hydrides, which may be described as having metallic bonding.
While these divisions have not been used universally, they are still useful to understand differences in hydrides. | 0 | Theoretical and Fundamental Chemistry |
Assume that:
*at t = 0 the transverse nuclear magnetization M(0) experiences a constant magnetic field B(t) = (0, 0, B);
*B is positive;
*there are no longitudinal and transverse relaxations (that is T and T → ∞).
Then the Bloch equations are simplified to:
These are two (not coupled) linear differential equations. Their solution is:
Thus the transverse magnetization, M, rotates around the z axis with angular frequency ω = γB in clockwise direction (this is due to the negative sign in the exponent).
The longitudinal magnetization, M remains constant in time. This is also how the transverse magnetization appears to an observer in the laboratory frame of reference (that is to a stationary observer).
M(t) is translated in the following way into observable quantities of M(t) and M(t): Since
then
where Re(z) and Im(z) are functions that return the real and imaginary part of complex number z. In this calculation it was assumed that M(0) is a real number. | 0 | Theoretical and Fundamental Chemistry |
A compact disk/digital versatile disk (CD/DVD) based immunoassay is a method for determining the concentration of a compound in research and diagnostic laboratories by performing the test on an adapted CD/DVD surface using an adapted optical disc drive; these methods have been discussed and prototyped in research labs since 1991. | 1 | Applied and Interdisciplinary Chemistry |
The HPCE-based viral titer assay uses a proprietary, high-performance capillary electrophoresis system to determine baculovirus titer.
The Trofile assay is used to determine HIV tropism.
The viral plaque assay is to calculate the number of viruses present in a sample. In this technique the number of viral plaques formed by a viral inoculum is counted, from which the actual virus concentration can be determined. | 1 | Applied and Interdisciplinary Chemistry |
Sustainable Islands International website reports that a 30kWh/8 kW prototype has been installed in Scotland to support a remote community and has been running successfully since 2013. This product has been recently selected by Canadian and UK governments to install large scale SLIQ battery systems to support the grid and to support storage of renewable generation. According to this news article in a British news paper this technology and supporting electronics will demonstrate how this energy storage systems can increase uptake of renewables, save money for customers and utilities, and accelerate carbon reductions by boosting the use of electric energy. The University of Strathclyde is leading a research project aimed at reducing the cost and improving the performance of battery technologies, for use in developing countries and emerging economies using this technology. With the development of this technology for developing countries, the faraday institute and University of Strathclyde believe they can help communities with low or no connectivity to have reliable access to energy sources and bringing economic, social and environment benefits to developing countries and emerging economies. In addition this technology has been used to set up a smart energy network for Perth & Kinross council to decarbonise all their assets and to achieve net-zero status. | 1 | Applied and Interdisciplinary Chemistry |
Adherents to the MaxEnt viewpoint take a clear position on some of the conceptual/philosophical questions in thermodynamics. This position is sketched below. | 0 | Theoretical and Fundamental Chemistry |
Cast iron farm tools and weapons were widespread in China by the 5th century BC, employing workforces of over 200 men in iron smelters from the 3rd century onward. The earliest known blast furnaces are attributed to the Han dynasty in the 1st century AD. These early furnaces had clay walls and used phosphorus-containing minerals as a flux. Chinese blast furnaces ranged from around two to ten meters in height, depending on the region. The largest ones were found in modern Sichuan and Guangdong, while the 'dwarf" blast furnaces were found in Dabieshan. In construction, they are both around the same level of technological sophistication
There is no evidence of the bloomery in China after the appearance of the blast furnace and cast iron. In China, blast furnaces produced cast iron, which was then either converted into finished implements in a cupola furnace, or turned into wrought iron in a fining hearth. If iron ores are heated with carbon to 1420–1470 K, a molten liquid is formed, an alloy of about 96.5% iron and 3.5% carbon. This product is strong, can be cast into intricate shapes, but is too brittle to be worked, unless the product is decarburized to remove most of the carbon. The vast majority of Chinese iron manufacture, from the late Zhou dynasty onward, was of cast iron. However forged swords began to be made in the Warring-States-period: "Earliest iron and steel Jian also appear, made by the earliest and most basic forging and folding techniques." Iron would become, by around 300 BCE, the preferred metal for tools and weapons in China.
The primary advantage of the early blast furnace was in large scale production and making iron implements more readily available to peasants. Cast iron is more brittle than wrought iron or steel, which required additional fining and then cementation or co-fusion to produce, but for menial activities such as farming it sufficed. By using the blast furnace, it was possible to produce larger quantities of tools such as ploughshares more efficiently than the bloomery. In areas where quality was important, such as warfare, wrought iron and steel were preferred. Nearly all Han period weapons are made of wrought iron or steel, with the exception of axe-heads, of which many are made of cast iron.
The effectiveness of the Chinese human and horse powered blast furnaces was enhanced during this period by the engineer Du Shi (c. AD 31), who applied the power of waterwheels to piston-bellows in forging cast iron. Early water-driven reciprocators for operating blast furnaces were built according to the structure of horse powered reciprocators that already existed. That is, the circular motion of the wheel, be it horse driven or water driven, was transferred by the combination of a belt drive, a crank-and-connecting-rod, other connecting rods, and various shafts, into the reciprocal motion necessary to operate a push bellow.
Donald Wagner suggests that early blast furnace and cast iron production evolved from furnaces used to melt bronze. Certainly, though, iron was essential to military success by the time the State of Qin had unified China (221 BC). Usage of the blast and cupola furnace remained widespread during the Song and Tang dynasties. By the 11th century, the Song dynasty Chinese iron industry made a switch of resources from charcoal to coke in casting iron and steel, sparing thousands of acres of woodland from felling. This may have happened as early as the 4th century AD.
Blast furnaces were also later used to produce gunpowder weapons such as cast iron bomb shells and cast iron cannons during the Song dynasty. | 1 | Applied and Interdisciplinary Chemistry |
Aliphatic alcohols give azides via a variant of the Mitsunobu reaction, with the use of hydrazoic acid. Hydrazines may also form azides by reaction with sodium nitrite: Alcohols can be converted into azides in one step using 2-azido-1,3-dimethylimidazolinium hexafluorophosphate (ADMP) or under Mitsunobu conditions with diphenylphosphoryl azide (DPPA). | 0 | Theoretical and Fundamental Chemistry |
The segments resulting from circularization during constructing jumping library are cleaved, and DNA fragments with markers will be enriched and subjected to paired-end sequencing.
These DNA fragments are sequenced from both ends and generate pairs of reads. The genomic distance between the reads in each pair is approximately known and used for the assembly process.
For example, a DNA clone generated by random fragmentation is about 200 bp, and a read from each end is around 180 bp, overlapping each other.
This should be distinguished from mate-pair sequencing, which is basically a combination of next generation sequencing with jumping libraries. | 1 | Applied and Interdisciplinary Chemistry |
Baku has the main moorings of all large vessels, such as oil tankers, in Azerbaijan. It is the largest port of the Caspian Sea. The port (and tankers) have access to the oceans along the Caspian Sea–Volga–Don Canal, and the Don–Sea of Azov. A northern alternate is the Volga–Baltic (a sea which has a connection to the North Sea of the Atlantic, as the White Sea does via the White Sea-Baltic canal). Baku Sea Trade Port and Caspian Shipping Company CJSC, have a big role in the sea transportation of Azerbaijan. The Caspian Sea Shipping Company CJSC has two fleets plus shipyards. Its transport fleet has 51 vessels: 20 tankers, 13 ferries, 15 universal dry cargo vessels, 2 Ro-Ro vessels, as well as 1 technical vessel and 1 floating workshop. Its specialized fleet has 210 vessels: 20 cranes, 25 towing and supplying vehicles, 26 passenger, two pipe-laying, six fire-fighting, seven engineering-geological, two diving and 88 auxiliary vessels.
The Caspian Sea Shipping Company of Azerbaijan, which acts as a liaison in the Transport Corridor Europe-Caucasus-Asia (TRACECA), simultaneously with the transportation of cargo and passengers in the Trans-Caspian direction, also performs work to fully ensure the processes of oil and gas production at sea. In the 19th century, the sharp increase in oil production in Baku gave a huge impetus to the development of shipping in the Caspian Sea, and as a result, there was a need to create fundamentally new floating facilities for the transportation of oil and oil products. | 1 | Applied and Interdisciplinary Chemistry |
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