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He died on 23 July 2007 in Munich. At the time of his death, Fischer was the oldest living German Nobel laureate. He was succeeded by Manfred Eigen, who shared the Nobel Prize in Chemistry in 1967 and is nine years younger than Fischer was. | 0 | Theoretical and Fundamental Chemistry |
Apricitabine is a deoxycytidine analogue. It is structurally related to lamivudine where the positions of the oxygen and the sulfur are essentially reversed. Even though apricitabine is a little less potent in vitro compared to some other NRTIs, it maintains its activity against a broad spectrum of HIV-1 variants with NRTI resistance mutations. Apricitabine is in the final stage of clinical development for the treatment of NRTI-experienced patients. | 1 | Applied and Interdisciplinary Chemistry |
Symptoms of nitrate poisoning in domestic animals include increased heart rate and respiration; in advanced cases blood and tissue may turn a blue or brown color. Feed can be tested for nitrate; treatment consists of supplementing or substituting existing supplies with lower nitrate material. Safe levels of nitrate for various types of livestock are as follows:
The values above are on a dry (moisture-free) basis. | 0 | Theoretical and Fundamental Chemistry |
Ramipril is marketed as Prilace by Arrow Pharmaceuticals in Australia, Ramipro by Westfield Pharma in the Philippines, Triatec by Sanofi-Aventis in Italy and United States and Altace by King Pharmaceuticals in the United States, Novapril by Pharmanova in Ghana, Ramitens by PharmaSwiss, Ampril by Krka in Slovenia, Corpril by Cemelog-BRS in Hungary, Piramil and Prilinda by Hemofarm in Serbia, by Lek in Poland and by Novartis and Opsonin Pharma Limited as Ramace in Bangladesh, and in Canada as Altace (Sanofi-Aventis) and Ramipril (Pharmascience).
Ramipril is marketed in India under the brand names Cardace, Zigpril, Ramistar, Odipril and Zorem . Ramipril is marketed in Myanmar under brand name Endpril . | 0 | Theoretical and Fundamental Chemistry |
There are several examples of molecules that present amphiphilic properties:
Hydrocarbon-based surfactants are an example group of amphiphilic compounds. Their polar region can be either ionic, or non-ionic. Some typical members of this group are: sodium dodecyl sulfate (anionic), benzalkonium chloride (cationic), cocamidopropyl betaine (zwitterionic), and 1-octanol (long-chain alcohol, non-ionic).
Many biological compounds are amphiphilic: phospholipids, cholesterol, glycolipids, fatty acids, bile acids, saponins, local anaesthetics, etc.
Soap is a common household amphiphilic surfactant compound. Soap mixed with water (polar, hydrophilic) is useful for cleaning oils and fats (non-polar, lipiphillic) from kitchenware, dishes, skin, clothing, etc. | 0 | Theoretical and Fundamental Chemistry |
Grev Brook; Bill Bowyer; David Davies; Mike Dewey; Bill Flavell; Philipp Gross; Eddie Sugars; GI Williams | 1 | Applied and Interdisciplinary Chemistry |
The human TRiC complex is formed by two rings containing 8 similar but non-identical subunits, each with molecular weights of ~60 kDa. The two rings are stacked in an asymmetrical fashion, forming a barrel-like structure with a molecular weight of ~1 MDa.
Molecular weight of human subunits.
Counterclockwise from the exterior, each ring is made of the subunits in the following order: 6-8-7-5-2-4-1-3. | 1 | Applied and Interdisciplinary Chemistry |
Sometimes drugs are formulated in an inactive form that is designed to break down inside the body to form the active drug. These are called prodrugs. The reasons for this type of formulation may be because the drug is more stable during manufacture and storage as the prodrug form, or because the prodrug is better absorbed by the body or has superior pharmacokinetics (e.g., lisdexamphetamine). | 1 | Applied and Interdisciplinary Chemistry |
The Boom method (Boom nucleic acid extraction method)
is a solid phase extraction method for isolating nucleic acids (NA)
from biological samples. Silica beads are a key element to this method, which are capable of binding the nucleic acids in the presence of a chaotropic substance according to the chaotropic effect.
This method is one of the most widespread methods for isolating nucleic acids from biological samples and is known as a simple, rapid, and reliable method for the small-scale purification of nucleic acid from biological sample.
This method is said to have been developed and invented by Willem R. Boom et al. around 1990.
While the chaotropic effect was previously known and reported by other scientists,
Boom et al. contributed an optimization of the method to complex starting materials, such as body fluids and other biological starting materials, and provided a short procedure according to the Boom et al. US5234809. After the Boom et al. patent was filed,
similar applications were also filed by other parties.
In a narrow sense, the word "silica" meant SiO crystals; however, other forms of silica particles are available.
In particular, amorphous silicon oxide and glass powder, alkylsilica, aluminum silicate (zeolite), or, activated
silica with -NH, are all suitable as nucleic acid binding solid phase material according to this method.
Today, the concepts of the Boom method, characterized by utilizing magnetic silica particles, are widely used. With this method, magnetic silica beads are captured by a magnetic bead collector, such as the Tajima pipette, Pick pen(R),
Quad Pole collector, and so on. | 1 | Applied and Interdisciplinary Chemistry |
The choice of working fluids is known to have a significant impact on the thermodynamic as well as economic performance of the cycle. A suitable fluid must exhibit favorable physical, chemical, environmental, safety and economic properties such as low specific volume (high density), viscosity, toxicity, flammability, ozone depletion potential (ODP), global warming potential (GWP) and cost, as well as favorable process characteristics such as high thermal and exergetic efficiency. These requirements apply both to pure (single-component) and mixed (multicomponent) working fluids. Existing research is largely focused on the selection of pure working fluids, with vast number of published reports currently available. An important restriction of pure working fluids is their constant temperature profile during phase change. Working fluid mixtures are more appealing than pure fluids because their evaporation temperature profile is variable, therefore follows the profile of the heat source better, as opposed to the flat (constant) evaporation profile of pure fluids. This enables an approximately stable temperature difference during evaporation in the heat exchanger, coined as temperature glide, which significantly reduces exergetic losses. Despite their usefulness, recent publications addressing the selection of mixed fluids are considerably fewer.<br>
Many authors like for example O. Badr et al. have suggested the following thermodynamic and physical criteria which a working fluid should meet for heat engines like Rankine cycles. There are some differences in the criteria concerning the working fluids used in heat engines and refrigeration cycles or heat pumps, which are listed below accordingly: | 0 | Theoretical and Fundamental Chemistry |
Harold Scott MacDonald "Donald" Coxeter (9 February 1907 – 31 March 2003) was a British-Canadian geometer and mathematician. | 0 | Theoretical and Fundamental Chemistry |
Cosmetics are mentioned in the Old Testament, such as in 2 Kings 9:30, where the biblical figure Jezebel painted her eyelids (approximately 840 BC). Cosmetics are also mentioned in the book of Esther, where beauty treatments are described.
Both sexes used cosmetics throughout the pre-Islamic Near East, going back to the civilizations of ancient Mesopotamia, Ancient Egypt, and Iran. Eye makeup in the form of kohl, were used in Persia and what today is Iran from ancient periods. Kohl is a black powder that was used widely across the Persian Empire. It was used as a powder or smeared to darken the edges of the eyelids similar to eyeliner. Cosmetics, especially kohl, played a significant role in the Middle East, highlighting not only its eye-protective aspects but also its cultural significance. The process of making kohl involved burning a substance to maintain a flame, a group of surfaces, and incorporating galena, a lead compound. Three items—jewelry, pottery, and seashells containing kohl—were buried with an ancient Emirati woman. Natural benefits of kohl also reduced eye swelling.
The Middle Easts adherence to Islamic rules shapes various aspects of daily life, including cosmetics and was also used throughout the Middle East and Near East after the advent of Islam. A specific type of kohl known as Ithmid kohl has been used for over 15 centuries in the region. In comparison to other types, Ithmid kohl not only has cosmetic benefits but also promotes health without harmful substances. Women used cosmetics widely in the private sphere, while only female slaves and singers tended to use them in public. Ointments, powders, and pastes were used as skin-lightening agents to comply with the eras beauty standards. Perfumed creams were also used on the face, as were sandalwood-based pastes to protect the skin from sunlight. Decorative henna was used during wedding celebrations to beautify the bride. Men and children used kohl on their eyes and henna as a natural dye for their hair, but rarely used other cosmetic items. | 1 | Applied and Interdisciplinary Chemistry |
Martell was born in Spencer, Massachusetts. He attended the U.S. Military Academy in West Point, New York. He was commissioned as a second lieutenant after graduating in 1942 and served in the Okinawa campaign of World War II, retiring with the rank of lieutenant colonel. He received a Ph.D. in radiochemistry from the University of Chicago in 1950. Willard Libby was Martell's mentor at the university through the late 1940s and early 1950s. | 0 | Theoretical and Fundamental Chemistry |
Class I PTPs constitute the largest family. They contain the well-known classical receptor (a) and non-receptor PTPs (b), which are strictly tyrosine-specific, and the DSPs (c) which target Ser/Thr as well as Tyr and are the most diverse in terms of substrate specificity. | 1 | Applied and Interdisciplinary Chemistry |
Source:
If a static membrane is modeled by a constant field and the structure of the field is such that it has a penetrable core and vanishes when , then
We see that in this case the sign and value depend on the potential and temperature only. | 0 | Theoretical and Fundamental Chemistry |
microRNA (miRNA) plays an important role in regulating gene expression. Majority of miRNAs are transcribed from DNA sequences into primary miRNAs. These primary miRNAs are further processed into precursor miRNAs, and finally into mature miRNAs. The miRNAs in most cases interact with the 3’ UTR region of target to induce mRNA degradation and translational repression. Interactions of miRNAs with other regions, including the 5’ UTR, coding sequence, and gene promoters have also been reported. Under certain conditions, miRNAs are also able to activate translation or regulate transcription, but this is dependent on factors such as location of the effect. This process of interaction is very dynamic and dependent on multiple factors. | 1 | Applied and Interdisciplinary Chemistry |
Although a plain metallic cathode will exhibit photoelectric properties, the specialized coating greatly increases the effect. A photocathode usually consists of alkali metals with very low work functions.
The coating releases electrons much more readily than the underlying metal, allowing it to detect the low-energy photons in infrared radiation. The lens transmits the radiation from the object being viewed to a layer of coated glass. The photons strike the metal surface and transfer electrons to its rear side. The freed electrons are then collected to produce the final image. | 0 | Theoretical and Fundamental Chemistry |
Bohr, Heisenberg, and others tried to explain what these experimental results and mathematical models really mean. The term Copenhagen interpretation has been applied to their views in retrospect, glossing over differences among them. While no definitive statement of "the" Copenhagen interpretation exists, the following ideas are widely seen as characteristic of it.
# A system is completely described by a quantum state (Heisenberg)
# How the quantum state changes over time is given by a wave equation, the Schrödinger equation imparting wave characteristics to light and matter.
# Atomic interactions are discontinuous. (Planck's quantum of action)
# The description of nature is essentially probabilistic. The probability of an event—for example, where on the screen a particle shows up in the double-slit experiment—is related to the square of the absolute value of the amplitude of its wave function. (Born rule, due to Max Born, which gives a physical meaning to the wave function in the Copenhagen interpretation: the probability amplitude)
# The values of incompatible pairs of properties of the system cannot be known at the same time. (Heisenberg's uncertainty principle)
# Matter, like light, exhibits a wave-particle duality. An experiment can demonstrate the particle-like properties of matter, or its wave-like properties; but not both at the same time. (Complementarity principle due to Bohr)
# Measuring devices are essentially classical devices and measure classical properties such as position and momentum.
# The quantum mechanical description of large systems should closely approximate the classical description. (Correspondence principle of Bohr and Heisenberg) | 1 | Applied and Interdisciplinary Chemistry |
M. acetivorans has been noted for its ability to metabolize carbon monoxide to form acetate and formate. It can also oxidize carbon monoxide into carbon dioxide. The carbon dioxide can then be converted into methane in a process which M. acetivorans uses to conserve energy. It has been suggested that this pathway may be similar to metabolic pathways used by primitive cells.
However, in the presence of minerals containing iron sulfides, as might have been found in sediments in a primordial environment, acetate would be catalytically converted into acetate thioester, a sulfur-containing derivative. Primitive microbes could obtain biochemical energy in the form of adenosine triphosphate (ATP) by converting acetate thioester back into acetate using PTS and ACK, which would then be converted back into acetate thioester to complete the process. In such an environment, a primitive "protocell" could easily produce energy through this metabolic pathway, excreting acetate as waste. Furthermore, ACK catalyzes the synthesis of ATP directly. Other pathways generate energy from ATP only through complex multi-enzyme reactions involving protein pumps and osmotic imbalances across a membrane. | 1 | Applied and Interdisciplinary Chemistry |
There have been suggestions that leaf shedding may be a response that provides protection against diseases and certain kinds of pests such as leaf miners and gall forming insects. Other responses such as the change of leaf colors prior to fall have also been suggested as adaptations that may help undermine the camouflage of herbivores. Autumn leaf color has also been suggested to act as an honest warning signal of defensive commitment towards insect pests that migrate to the trees in autumn. | 1 | Applied and Interdisciplinary Chemistry |
Physiological agonism describes the action of a substance which ultimately produces the same effects in the body as another substance—as if they were both agonists at the same receptor—without actually binding to the same receptor. Physiological antagonism describes the behavior of a substance that produces effects counteracting those of another substance (a result similar to that produced by an antagonist blocking the action of an agonist at the same receptor) using a mechanism that does not involve binding to the same receptor. | 1 | Applied and Interdisciplinary Chemistry |
Fungi are amongst the primary saprotrophic organisms in an ecosystem, as they are efficient in the decomposition of matter. Wood-decay fungi, especially white rot, secretes extracellular enzymes and acids that break down lignin and cellulose, the two main building blocks of plant fiber. These are long-chain organic (carbon-based) compounds, structurally similar to many organic pollutants. They achieve this using a wide array of enzymes. In the case of polycyclic aromatic hydrocarbons (PAHs), complex organic compounds with fused, highly stable, polycyclic aromatic rings, fungi are very effective in addition to marine environments. The enzymes involved in this degradation are ligninolytic and include lignin peroxidase, versatile peroxidase, manganese peroxidase, general lipase, laccase and sometimes intracellular enzymes, especially the cytochrome P450.
Other toxins fungi are able to degrade into harmless compounds include petroleum fuels, phenols in wastewater, polychlorinated biphenyl (PCB) in contaminated soils using Pleurotus ostreatus, polyurethane in aerobic and anaerobic conditions, such as conditions at the bottom of landfills using two species of the Ecuadorian fungus Pestalotiopsis, and more.
The mechanisms of degradation are not always clear, as the mushroom may be a precursor to subsequent microbial activity rather than individually effective in the removal of pollutants. | 1 | Applied and Interdisciplinary Chemistry |
Ventilation guidelines are based on the minimum ventilation rate required to maintain acceptable levels of effluents. Carbon dioxide is used as a reference point, as it is the gas of highest emission at a relatively constant value of 0.005 L/s. The mass balance equation is:
Q = G/(C − C)
*Q = ventilation rate (L/s)
*G = CO generation rate
*C = acceptable indoor CO concentration
*C = ambient CO concentration | 1 | Applied and Interdisciplinary Chemistry |
Settling basins and clarifiers are designed to retain water so that suspended solids can settle. By sedimentation principles, the suitable treatment technologies should be chosen depending on the specific gravity, size and shear resistance of particles. Depending on the size and density of particles, and physical properties of the solids, there are four types of sedimentation processes:
* Type 1 – Dilutes, non-flocculent, free-settling (every particle settles independently.)
* Type 2 – Dilute, flocculent (particles can flocculate as they settle).
* Type 3 – Concentrated suspensions, zone settling, hindered settling (sludge thickening).
* Type 4 – Concentrated suspensions, compression (sludge thickening).
Different factors control the sedimentation rate in each. | 0 | Theoretical and Fundamental Chemistry |
The Royal Australian Chemical Institute (RACI) is both the qualifying body in Australia for professional chemists and a learned society promoting the science and practice of chemistry in all its branches. The RACI hosts conferences, seminars and workshops. It is the professional body for chemistry in Australia, with the ability to award the status of Chartered Chemist (CChem) to suitably qualified candidates. | 1 | Applied and Interdisciplinary Chemistry |
Lupeol is a pharmacologically active pentacyclic triterpenoid. It has several potential medicinal properties, like anticancer and anti-inflammatory activity. | 0 | Theoretical and Fundamental Chemistry |
Transforming growth factor beta-1-induced transcript 1 protein is a protein that in humans is encoded by the TGFB1I1 gene. Often put together with and studied alongside TGFB1I1 is the mouse homologue HIC-5 ( Hydrogen Peroxide-Inducible Clone-5). As the name suggests, TGFB1I1 is an induced form of the larger family of TGFB1. Studies suggest TGFB1I1 plays a role in processes of cell growth, proliferation, migration, differentiation and senescence. TGFB1I1 is most localized at focal adhesion complexes of cells, although it may be found active in the cytosol, nucleus and cell membrane as well. | 1 | Applied and Interdisciplinary Chemistry |
A contaminant is a substance present in nature at a level higher than fixed levels or that would not otherwise be there. This may be due to human activity and bioactivity. The term contaminant is often used interchangeably with pollutant, which is a substance that has a detrimental impact on the surrounding environment. Whilst a contaminant is sometimes defined as a substance present in the environment as a result of human activity, but without harmful effects, it is sometimes the case that toxic or harmful effects from contamination only become apparent at a later date.
The "medium" such as soil or organism such as fish affected by the pollutant or contaminant is called a receptor, whilst a sink is a chemical medium or species that retains and interacts with the pollutant such as carbon sink and its effects by microbes. | 1 | Applied and Interdisciplinary Chemistry |
Two mole of is split into 1 mole and 2 mole using light in the process shown below.
A photon with an energy greater than 1.23 eV is needed to generate an electron–hole pairs, which react with water on the surface of the photocatalyst. The photocatalyst must have a bandgap large enough to split water; in practice, losses from material internal resistance and the overpotential of the water splitting reaction increase the required bandgap energy to 1.6–2.4 eV to drive water splitting.
The process of water-splitting is a highly endothermic process (ΔH > 0). Water splitting occurs naturally in photosynthesis when the energy of four photons is absorbed and converted into chemical energy through a complex biochemical pathway (Dolais or Koks S-state diagrams).
O–H bond homolysis in water requires energy of 6.5 - 6.9 eV (UV photon). Infrared light has sufficient energy to mediate water splitting because it technically has enough energy for the net reaction. However, it does not have enough energy to mediate the elementary reactions leading to the various intermediates involved in water splitting (this is why there is still water on Earth). Nature overcomes this challenge by absorbing four visible photons. In the laboratory, this challenge is typically overcome by coupling the hydrogen production reaction with a sacrificial reductant other than water.
Materials used in photocatalytic water splitting fulfill the band requirements and typically have dopants and/or co-catalysts added to optimize their performance. A sample semiconductor with the proper band structure is titanium dioxide () and is typically used with a co-catalyst such as platinum (Pt) to increase the rate of production. A major problem in photocatalytic water splitting is photocatalyst decomposition and corrosion. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, axial chirality is a special case of chirality in which a molecule contains two pairs of chemical groups in a non-planar arrangement about an axis of chirality so that the molecule is not superposable on its mirror image. The axis of chirality (or chiral axis) is usually determined by a chemical bond that is constrained against free rotation either by steric hindrance of the groups, as in substituted biaryl compounds such as BINAP, or by torsional stiffness of the bonds, as in the C=C double bonds in allenes such as glutinic acid. Axial chirality is most commonly observed in substituted biaryl compounds wherein the rotation about the aryl–aryl bond is restricted so it results in chiral atropisomers, as in various ortho-substituted biphenyls, and in binaphthyls such as BINAP.
Axial chirality differs from central chirality (point chirality) in that axial chirality does not require a chiral center such as an asymmetric carbon atom, the most common form of chirality in organic compounds. Bonding to asymmetric carbon has the form Cabcd where a, b, c, and d must be distinct groups. Allenes have the form and the groups need not all be distinct as long as groups in each pair are distinct: abC=C=Cab is sufficient for the compound to be chiral, as in penta-2,3-dienedioic acid. Similarly, chiral atropisomers of the form may have some identical groups (), as in BINAP. | 0 | Theoretical and Fundamental Chemistry |
Pectins are a family of complex polysaccharides that contain 1,4-linked α--galactosyl uronic acid residues. They are present in most primary cell walls and in the nonwoody parts of terrestrial plants. | 0 | Theoretical and Fundamental Chemistry |
Zinc is the second most abundant transition metal present in living organisms second only to iron. It is critical for the growth and survival of cells. In humans, zinc is primarily found in various organs and tissues such as the brain, intestines, pancreas and mammary glands. In prokaryotes, zinc can function as an antimicrobial, zinc oxide nano-particles can function as an antibacterial or antibiotic. Zinc homeostasis is highly controlled to allow for its benefits without risk of death via its high toxicity. Because of zinc's antibiotic nature, it is often used in many drugs against bacterial infections in humans. Inversely, due to the bacterial nature of mitochondria, zinc antibiotics are also lethal to mitochondria and results in cell death at high concentrations. Zinc is also used in a number of transcription factors, proteins and enzymes. | 1 | Applied and Interdisciplinary Chemistry |
The vulcanization of rubber results in crosslinking groups which consist of disulfide (and polysulfide) bonds; in analogy to the role of disulfides in proteins, the S−S linkages in rubber strongly affect the stability and rheology of the material. Although the exact mechanism underlying the vulcanization process is not entirely understood (as multiple reaction pathways are present but the predominant one is unknown), it has been extensively shown that the extent to which the process is allowed to proceed determines the physical properties of the resulting rubber- namely, a greater degree of crosslinking corresponds to a stronger and more rigid material. The current conventional methods of rubber manufacturing are typically irreversible, as the unregulated reaction mechanisms can result in complex networks of sulfide linkages; as such, rubber is considered to be a thermoset material. | 0 | Theoretical and Fundamental Chemistry |
Unusual waves have been studied scientifically for many years (for example, John Scott Russells wave of translation, an 1834 study of a soliton wave). Still, these were not linked conceptually to sailors stories of encounters with giant rogue ocean waves, as the latter were believed to be scientifically implausible.
Since the 19th century, oceanographers, meteorologists, engineers, and ship designers have used a statistical model known as the Gaussian function (or Gaussian Sea or standard linear model) to predict wave height, on the assumption that wave heights in any given sea are tightly grouped around a central value equal to the average of the largest third, known as the significant wave height (SWH). In a storm sea with an SWH of , the model suggests hardly ever would a wave higher than occur. It suggests one of could indeed happen, but only once in 10,000 years. This basic assumption was well accepted, though acknowledged to be an approximation. Using a Gaussian form to model waves has been the sole basis of virtually every text on that topic for the past 100 years.
The first known scientific article on "freak waves" was written by Professor Laurence Draper in 1964. In that paper, he documented the efforts of the National Institute of Oceanography in the early 1960s to record wave height, and the highest wave recorded at that time, which was about . Draper also described freak wave holes.
Even as late as the mid-1990s, though, most popular texts on oceanography such as that by Pirie did not contain any mention of rogue or freak waves. Even after the 1995 Draupner wave, the popular text on Oceanography by Gross (1996) only gave rogue waves a mention and simply stated, "Under extraordinary circumstances, unusually large waves called rogue waves can form" without providing any further detail. | 1 | Applied and Interdisciplinary Chemistry |
Fluorophores are essential to our measurement of the metal binding event, and indirectly, metal concentration. There are many types, all with different properties that make them advantageous for different applications. Some work as small metal sensors completely on their own while others must be complexed with a subunit that can chelate or bind a metal ion. Rhodamine for example undergoes a conformation change upon the binding of a metal ion. In so doing it switches between a colorless, non-fluorescent spirocyclic form to a fluorescent, pink open cyclic form. Quinoline based sensors have been developed that form luminescent complexes with Cd(II) and fluorescent ones with Zn(II). It is hypothesized to function by changing its lowest luminescent state from n–* to –* when coordinating to a metal.
When the Dansyl group DNS binds to a metal, it loses a sulfonamide hydrogen, causing fluorescence quenching via a PET or reverse PET mechanism in which an electron is transferred either to or from the metal that is bound. | 0 | Theoretical and Fundamental Chemistry |
Zeta potential titrations are titrations in which the completion is monitored by the zeta potential, rather than by an indicator, in order to characterize heterogeneous systems, such as colloids. One of the uses is to determine the iso-electric point when surface charge becomes zero, achieved by changing the pH or adding surfactant. Another use is to determine the optimum dose for flocculation or stabilization. | 0 | Theoretical and Fundamental Chemistry |
The pits that penetrate the bore are usually covered in a hard pale green nodule of copper sulfate and copper hydroxide salts. If the nodule is removed a hemispherical pit is revealed filled with coarse crystals of red cuprous oxide and green cuprous chloride. The pits are often referred to as Type 1 pits and the form of attack as Type 1 pitting. | 1 | Applied and Interdisciplinary Chemistry |
A metallacarboxylic acid is a metal complex with the ligand COH. These compounds are intermediates in reactions that involve carbon monoxide and carbon dioxide, these species are intermediates in the water gas shift reaction. Metallacarboxylic acids are also called hydroxycarbonyls. | 0 | Theoretical and Fundamental Chemistry |
Note: These lists are illustrative, not exhaustive, and identification of noise sources is an active and expanding area of research.
;Intrinsic noise
* Low copy-number effects (including discrete birth and death events): the random (stochastic) nature of production and degradation of cellular components means that noise is high for components at low copy number (as the magnitude of these random fluctuations is not negligible with respect to the copy number);
* Diffusive cellular dynamics: many important cellular processes rely on collisions between reactants (for example, RNA polymerase and DNA) and other physical criteria which, given the diffusive dynamic nature of the cell, occur stochastically.
* Noise propagation: Low copy-number effects and diffusive dynamics result in each of the biochemical reactions in a cell occurring randomly. Stochasticity of reactions can be either attenuated or amplified. Contribution each reaction makes to the intrinsic variability in copy numbers can be quantified via Van Kampen's system size expansion.
;Extrinsic noise
* Cellular age / cell cycle stage: cells in a dividing population that is not synchronised will, at a given snapshot in time, be at different cell cycle stages, with corresponding biochemical and physical differences;
* Cell growth: variations in growth rates leading to concentration variations between cells;
* Physical environment (temperature, pressure, ...): physical quantities and chemical concentrations (particularly in the case of cell-to-cell signalling) may vary spatially across a population of cells, provoking extrinsic differences as a function of position;
* Organelle distributions: random factors in the quantity and quality of organelles (for example, the number and functionality of mitochondria) lead to significant cell-to-cell differences in a range of processes (as, for example, mitochondria play a central role in the energy budget of eukaryotic cells);
* Inheritance noise: uneven partitioning of cellular components between daughter cells at mitosis can result in large extrinsic differences in a dividing population.
* Regulator competition: Regulators competing to bind downstream promoters can cause negative correlations: when one promoter is bound the other is not and vice versa.
Note that extrinsic noise can affect levels and types of intrinsic noise: for example, extrinsic differences in the mitochondrial content of cells lead, through differences in ATP levels, to some cells transcribing faster than others, affecting the rates of gene expression and the magnitude of intrinsic noise across the population. | 1 | Applied and Interdisciplinary Chemistry |
Numerous sAC splice variants are present in osteoclast and osteoblasts, and mutation in the human sAC gene is associated with low spinal density. Calcification by osteoblasts is intrinsically related with bicarbonate and calcium. Bone density experiments in mouse calvaria cultured indicates that HCO-sensing sAC is a physiological appropriate regulator of bone formation and/or reabsorption. | 1 | Applied and Interdisciplinary Chemistry |
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from Latin ligare, which means to bind. In protein-ligand binding, the ligand is usually a molecule which produces a signal by binding to a site on a target protein. The binding typically results in a change of conformational isomerism (conformation) of the target protein. In DNA-ligand binding studies, the ligand can be a small molecule, ion, or protein which binds to the DNA double helix. The relationship between ligand and binding partner is a function of charge, hydrophobicity, and molecular structure.
Binding occurs by intermolecular forces, such as ionic bonds, hydrogen bonds and Van der Waals forces. The association or docking is actually reversible through dissociation. Measurably irreversible covalent bonding between a ligand and target molecule is atypical in biological systems. In contrast to the definition of ligand in metalorganic and inorganic chemistry, in biochemistry it is ambiguous whether the ligand generally binds at a metal site, as is the case in hemoglobin. In general, the interpretation of ligand is contextual with regards to what sort of binding has been observed.
Ligand binding to a receptor protein alters the conformation by affecting the three-dimensional shape orientation. The conformation of a receptor protein composes the functional state. Ligands include substrates, inhibitors, activators, signaling lipids, and neurotransmitters. The rate of binding is called affinity, and this measurement typifies a tendency or strength of the effect. Binding affinity is actualized not only by host–guest interactions, but also by solvent effects that can play a dominant, steric role which drives non-covalent binding in solution. The solvent provides a chemical environment for the ligand and receptor to adapt, and thus accept or reject each other as partners.
Radioligands are radioisotope labeled compounds used in vivo as tracers in PET studies and for in vitro binding studies. | 1 | Applied and Interdisciplinary Chemistry |
The General Meeting of the Association is the ultimate authority in the Association. A delegate of each ECCA member company is appointed to participate in and vote at the General Meeting of the Association.
The Executive Committee comprises the President, the immediate Past-President, the Vice-President, the Marketing Committee, the Technical Committee, the Environment and Sustainability Committee chairs and the Managing Director of the Association.
The Board of Directors includes the members of the Executive Committee plus some other members elected by the General Meeting. In 2013, there are 16 Board members.
The Head office is responsible for the day-to-day management of the Association. 4 staff members are working on a full-time basis (in 2013).
ECCA is also nationally represented in France, Germany, the UK, Italy, the Netherlands, and Nordic Countries. | 1 | Applied and Interdisciplinary Chemistry |
Index inducer or just inducer predictably induce metabolism via a given pathway and are commonly used in prospective clinical drug-drug interaction studies.
Strong, moderate, and weak inducers are drugs that decreases the AUC of sensitive index substrates of a given metabolic pathway by ≥80%, ≥50% to <80%, and ≥20% to <50%, respectively. | 0 | Theoretical and Fundamental Chemistry |
The basic tool required for the derivation of the RANS equations from the instantaneous Navier–Stokes equations is the Reynolds decomposition. Reynolds decomposition refers to separation of the flow variable (like velocity ) into the mean (time-averaged) component () and the fluctuating component (). Because the mean operator is a Reynolds operator, it has a set of properties. One of these properties is that the mean of the fluctuating quantity is equal to zero . Thus,
where is the position vector. Some authors prefer using instead of for the mean term (since an overbar is sometimes used to represent a vector). In this case, the fluctuating term is represented instead by . This is possible because the two terms do not appear simultaneously in the same equation. To avoid confusion, the notation , , and will be used to represent the instantaneous, mean, and fluctuating terms, respectively.
The properties of Reynolds operators are useful in the derivation of the RANS equations. Using these properties, the Navier–Stokes equations of motion, expressed in tensor notation, are (for an incompressible Newtonian fluid):
where is a vector representing external forces.
Next, each instantaneous quantity can be split into time-averaged and fluctuating components, and the resulting equation time-averaged,
to yield:
The momentum equation can also be written as,
On further manipulations this yields,
where, is the mean rate of strain tensor.
Finally, since integration in time removes the time dependence of the resultant terms, the time derivative must be eliminated, leaving: | 1 | Applied and Interdisciplinary Chemistry |
Milk is presently the most mature system to produce recombinant proteins from transgenic organisms. Blood, egg white, seminal plasma, and urine are other theoretically possible systems, but all have drawbacks. Blood, for instance, as of 2012 cannot store high levels of stable recombinant proteins, and biologically active proteins in blood may alter the health of the animals. Expression in the milk of a mammal, such as a cow, sheep, or goat, is a common application, as milk production is plentiful and purification from milk is relatively easy. Hamsters and rabbits have also been used in preliminary studies because of their faster breeding.
One approach to this technology is the creation of a transgenic mammal that can produce the biopharmaceutical in its milk (or blood or urine). Once an animal is produced, typically using the pronuclear microinjection method, it becomes efficacious to use cloning technology to create additional offspring that carry the favorable modified genome. In February 2009 the US FDA granted marketing approval for the first drug to be produced in genetically modified livestock. The drug is called ATryn, which is antithrombin protein purified from the milk of genetically modified goats. Marketing permission was granted by the European Medicines Agency in August 2006. | 1 | Applied and Interdisciplinary Chemistry |
The term photoprotein was first used to describe the unusual chemistry of the luminescent system of Chaetopterus (a marine Polychaete worm). This was meant to distinguish them from other light-producing proteins because these do not exhibit the usual luciferin-luciferase reaction. | 1 | Applied and Interdisciplinary Chemistry |
Through hot-isostatically pressing (HIP) a ZrWO-Cu composite (system) can be realized. Work done by C. Verdon and D.C. Dunand in 1997 used similarly sized zirconium tungstate and copper powder in a low carbon steel can coated with Cu, and they were HIPed under 103MPa pressure for 3 hours at 600 °C. A control experiment was also conducted, with only a heat treatment (i.e., no pressing) for the same powder mixture also under 600 °C for 3 hours in a quartz tube gettered with titanium.
The results from X-ray diffraction (XRD) in the graph in Verdon & Dunand's paper shows expected products. (a) is from the as received zirconium tungstate powder, (b) is the result from the control experiment , and (c) is the ceramic product from the HIP process. Apparently there are new phases formed according to Spectrum (c) with no ZrWO left. While for the control experiment only partial amount of ZrWO was decomposed.
While complex oxides containing Cu, Zr, and W were believed to be created, selected area diffraction (SAD) of the ceramic product has proven the existence of CuO as precipitates after reaction. A model consisted of two concurrent processes were surmised (as presented): (b) the decomposition of the ceramic and loss of oxygen under low oxygen partial pressure at high temperature leads to CuO formation; (c) copper diffuses into the ceramic and forms new oxides that absorb some oxygen upon cooling.
Since only very few oxides, those of noble metals which are very expensive, are less stable than CuO and CuO was believed to be more stable than ZrWO, kinetic control of the reaction must be taken into account. For example, reducing reaction time and temperature helps alleviate the residual stress caused by different phases of the ceramic during reaction, which could lead to a delamination of the ceramic particles from the matrix and an increase in the CTE. | 0 | Theoretical and Fundamental Chemistry |
Legal regulations usually require that sales to end customers be compensated to the legally defined base conditions. Where regulations do not require the use of a specific set of base conditions, contractual partners may be free to choose their own base conditions.
Base conditions are often defined jurisdictionally. For example: | 1 | Applied and Interdisciplinary Chemistry |
The Woodward–Hoffmann rules can be stated succinctly as a single sentence: A ground-state pericyclic process is brought about by addition of thermal energy (i.e., heating the system, symbolized by Δ). In contrast, an excited-state pericyclic process takes place if a reactant is promoted to an electronically excited state by activation with ultraviolet light (i.e., irradiating the system, symbolized by hν). It is important to recognize, however, that the operative mechanism of a formally pericyclic reaction taking place under photochemical irradiation is generally not as simple or clearcut as this dichotomy suggests. Several modes of electronic excitation are usually possible, and electronically excited molecules may undergo intersystem crossing, radiationless decay, or relax to an unfavorable equilibrium geometry before the excited-state pericyclic process can take place. Thus, many apparent pericyclic reactions that take place under irradiation are actually thought to be stepwise processes involving diradical intermediates. Nevertheless, it is frequently observed that the pericyclic selection rules become reversed when switching from thermal to photochemical activation. This can be rationalized by considering the correlation of the first electronic excited states of the reactants and products. Although more of a useful heuristic than a rule, a corresponding generalized selection principle for photochemical pericyclic reactions can be stated: Pericyclic reactions involving an odd number of electrons are also known. With respect to application of the generalized pericyclic selection rule, these systems can generally be treated as though one more electron were involved.
In the language of aromatic transition state theory, the Woodward–Hoffmann rules can be restated as follows: A pericyclic transition state involving (4n + 2) electrons with Hückel topology or 4n electrons with Möbius topology is aromatic and allowed, while a pericyclic transition state involving 4n-electrons with Hückel topology or (4n + 2)-electrons with Möbius topology is antiaromatic and forbidden. | 0 | Theoretical and Fundamental Chemistry |
The Hüttenwerke Kayser smelter at Lünen in Germany installed an ISASMELT plant in 2002 to replace three blast furnaces and one Peirce-Smith converter used for smelting scrap copper. The company was subsequently bought by Norddeutsche Affinerie AG, which in turn became Aurubis.
The process used at the Lünen smelter involves charging the furnace with copper residues and scrap containing between 1 and 80% copper and then melting it in a reducing environment. This produces a "black copper phase" and a low-copper silica slag. Initially the black copper was converted to blister copper in the ISASMELT furnace. However, in 2011 the smelter was expanded as part of the "KRS Plus" project. A top-blown rotary converter is used to convert the black copper and the ISASMELT furnace runs continuously in smelting mode.
The installation of the ISASMELT furnace increased the overall copper recovery in the plant by reducing losses to slag, reduced the number of furnaces in operation, decreased the waste gas volume, and decreased energy consumption by more than 50%. The production capacity exceeds the original design by 40%.
Kandanshi
Atlantic Copper | 1 | Applied and Interdisciplinary Chemistry |
Flora on Pandora are of a tropical type several times taller than that existing on Earth. Many, if not all, plant and animal species have bioluminescent properties. The flora specimens seen in the film were all designed by Jodie Holt, a professor of botany at the University of California, Riverside. According to Holt, Pandoran flora are able to communicate with each other through signal transduction and are larger in size than Earth flora due to greater atmospheric thickness, weaker gravity, and stronger magnetism on Pandora. | 1 | Applied and Interdisciplinary Chemistry |
Figure 4 shows the orbital array involved in the butadiene to cyclobutene interconversion. It is seen that there are four orbitals in this cyclic array. Thus in the interconversion reactions orbitals 1 and 4 overlap either in a conrotatory or a disrotatory fashion. Also, it is seen that the conrotation involves one plus-minus overlap as drawn while the disrotation involves zero plus-minus overlaps as drawn. Thus the conrotation uses a Möbius array while the disrotation uses a Hückel array.
But it is important to note, as described for the generalized orbital array in Figure 3, that the assignment of the basis-set p-orbitals is arbitrary. Were one p-orbital in either reaction mode to be written upside-down, this would change the number of sign inversions by two and not change the evenness or oddness of the orbital array.
With a conrotation giving a Möbius system, with butadiene's four electrons, we find an "allowed" reaction model. With disrotation giving a Hückel system, with the four electrons, we find a "forbidden" reaction model.
Although in these two examples symmetry is present, symmetry is not required or involved in determination of reaction allowedness versus forbiddenness. Hence a very large number of organic reactions can be understood. Even where symmetry is present, the Möbius–Hückel analysis proves simple to employ. | 0 | Theoretical and Fundamental Chemistry |
Early approximations for smooth pipes by Paul Richard Heinrich Blasius in terms of the Darcy–Weisbach friction factor are given in one article of 1913:
Johann Nikuradse in 1932 proposed that this corresponds to a power law correlation for the fluid velocity profile.
Mishra and Gupta in 1979 proposed a correction for curved or helically coiled tubes, taking into account the equivalent curve radius, R:
with,
where f is a function of:
* Pipe diameter, D (m, ft)
* Curve radius, R (m, ft)
* Helicoidal pitch, H (m, ft)
* Reynolds number, Re (dimensionless)
valid for:
* Re
* 6.7 /D < 346.0
* 0 < H/D < 25.4 | 1 | Applied and Interdisciplinary Chemistry |
Birds have bony beaks that are specialised according to the bird's ecological niche. For example, macaws primarily eat seeds, nuts, and fruit, using their beaks to open even the toughest seed. First they scratch a thin line with the sharp point of the beak, then they shear the seed open with the sides of the beak.
The mouth of the squid is equipped with a sharp horny beak mainly made of cross-linked proteins. It is used to kill and tear prey into manageable pieces. The beak is very robust, but does not contain any minerals, unlike the teeth and jaws of many other organisms, including marine species. The beak is the only indigestible part of the squid. | 1 | Applied and Interdisciplinary Chemistry |
Active flow control by MHD force fields on the contrary involves a direct and imperious action of forces to locally accelerate or slow down the airflow, modifying its velocity, direction, pressure, friction, heat flux parameters, in order to preserve materials and engines from stress, allowing hypersonic flight. It is a field of magnetohydrodynamics also called magnetogasdynamics, magnetoaerodynamics or magnetoplasma aerodynamics, as the working fluid is the air (a gas instead of a liquid) ionized to become electrically conductive (a plasma).
Air ionization is achieved at high altitude (electrical conductivity of air increases as atmospheric pressure reduces according to Paschen's law) using various techniques: high voltage electric arc discharge, RF (microwaves) electromagnetic glow discharge, laser, e-beam or betatron, radioactive source… with or without seeding of low ionization potential alkali substances (like caesium) into the flow.
MHD studies applied to aeronautics try to extend the domain of hypersonic planes to higher Mach regimes:
* Action on the boundary layer to prevent laminar flow from becoming turbulent.
* Shock wave mitigation for thermal control and reduction of the wave drag and form drag. Some theoretical studies suggest the flow velocity could be controlled everywhere on the wetted area of an aircraft, so shock waves could be totally cancelled when using enough power.
* Inlet flow control.
* Airflow velocity reduction upstream to feed a scramjet by the use of an MHD generator section combined with an MHD accelerator downstream at the exhaust nozzle, powered by the generator through an MHD bypass system.
The Russian project Ayaks (Ajax) is an example of MHD-controlled hypersonic aircraft concept. A US program also exists to design a hypersonic MHD bypass system, the Hypersonic Vehicle Electric Power System (HVEPS). A working prototype was completed in 2017 under development by General Atomics and the University of Tennessee Space Institute, sponsored by the US Air Force Research Laboratory. These projects aim to develop MHD generators feeding MHD accelerators for a new generation of high-speed vehicles. Such MHD bypass systems are often designed around a scramjet engine, but easier to design turbojets are also considered, as well as subsonic ramjets.
Such studies covers a field of resistive MHD with magnetic Reynolds number ≪ 1 using nonthermal weakly ionized gases, making the development of demonstrators much more difficult to realize than for MHD in liquids. "Cold plasmas" with magnetic fields are subject to the electrothermal instability occurring at a critical Hall parameter, which makes full-scale developments difficult. | 1 | Applied and Interdisciplinary Chemistry |
A core set of energy-producing catabolic pathways occur within all living organisms in some form. These pathways transfer the energy released by breakdown of nutrients into ATP and other small molecules used for energy (e.g. GTP, NADPH, FADH). All cells can perform anaerobic respiration by glycolysis. Additionally, most organisms can perform more efficient aerobic respiration through the citric acid cycle and oxidative phosphorylation. Additionally plants, algae and cyanobacteria are able to use sunlight to anabolically synthesize compounds from non-living matter by photosynthesis. | 1 | Applied and Interdisciplinary Chemistry |
Block copolymers are interesting because they can "microphase separate" to form periodic nanostructures,[13][14][15] Microphase separation is a situation similar to that of oil and water. Oil and water are immiscible - they phase separate. Due to incompatibility between the blocks, block copolymers undergo a similar phase separation. Because the blocks are covalently bonded to each other, they cannot demix macroscopically as water and oil. In "microphase separation" the blocks form nanometer-sized structures. | 0 | Theoretical and Fundamental Chemistry |
The steam digester or bone digester (also known as Papin’s digester) is a high-pressure cooker invented by French physicist Denis Papin in 1679. It is a device for extracting fats from bones in a high-pressure steam environment, which also renders them brittle enough to be easily ground into bone meal. It is the forerunner of the autoclave and the domestic pressure cooker.
The steam-release valve, which was invented for Papin's digester following various explosions of the earlier models, inspired the development of the piston-and-cylinder steam engine. | 0 | Theoretical and Fundamental Chemistry |
The definition of ecosan is focusing on the health, environment and resource aspect of sustainable sanitation. Thus ecosan is not, per se, sustainable sanitation, but ecosan systems can be implemented in a sustainable way and have a strong potential for sustainable sanitation, if technical, institutional, social and economical aspects are cared for appropriately. Ecosan systems can be "unsustainable" for example if there is too little user acceptance or if the costs of the system are too high for a given target group of users, making the system financially unsustainable in the longer term. | 1 | Applied and Interdisciplinary Chemistry |
He is a related ion bonded by a half covalent bond. It can be formed in a helium electrical discharge. It recombines with electrons to form an electronically excited He(aΣ) excimer molecule. Both of these molecules are much smaller with more normally sized interatomic distances. He reacts with N, Ar, Xe, O, and CO to form cations and neutral helium atoms.
The helium dication dimer He is extremely repulsive and releases much energy when it dissociates, around 835 kJ/mol. Dynamical stability of the ion was predicted by Linus Pauling. An energy barrier of 138.91 kJ/mol prevents immediate decay. This ion is isoelectronic with the hydrogen molecule. He is the smallest possible molecule with a double positive charge. It is detectable using mass spectroscopy.
The negative helium dimer He is metastable and was discovered by Bae, Coggiola and Peterson in 1984 by passing He through cesium vapor. Subsequently, H. H. Michels theoretically confirmed its existence and concluded that the Π state of He is bound relative to the aΣ state of He. The calculated electron affinity is 0.233 eV compared to 0.077 eV for the He[P] ion. The He decays through the long-lived 5/2g component with τ~350 μsec and the much shorter-lived 3/2g, 1/2g components with τ~10 μsec. The Π state has a 1σ1σ2σ2π electronic configuration, its electron affinity E is 0.18±0.03 eV, and its lifetime is 135±15 μsec; only the v=0 vibrational state is responsible for this long-lived state.
The molecular helium anion is also found in liquid helium that has been excited by electrons with an energy level higher than 22 eV. This takes place firstly by penetration of liquid He, taking 1.2 eV, followed by excitation of a He atom electron to the P level, which takes 19.8 eV. The electron can then combine with another helium atom and the excited helium atom to form He. He repels helium atoms, and so has a void around it. It will tend to migrate to the surface of liquid helium. | 0 | Theoretical and Fundamental Chemistry |
The calculation of Ki using arterial input function, time-activity curve, and Hawkins model was limited to a small skeletal region covered by the narrow field-of-view of the PET scanner while acquiring a dynamic scan. However, Siddique et al. showed in 2012 that it is possible to measure K values in bones using static [F]NaF PET scans. Blake et al. later showed in 2019 that the K obtained using the Siddique–Blake method has precision errors of less than 10%. The Siddique–Blake approach is based on the combination of the Patlak method, the semi-population based arterial input function, and the information that V does not significantly change post-treatment. This method uses the information that a linear regression line can be plotted using the data from a minimum of two time-points, to obtain m and c as explained in the Patlak method. However, if V is known or fixed, only one single static PET image is required to obtain the second time-point to measure m, representing the K value. This method should be applied with great caution to other clinical areas where these assumptions may not hold true. | 1 | Applied and Interdisciplinary Chemistry |
Massively parallel reporter assays is a technology to test the cis-regulatory activity of DNA sequences. MPRAs use a plasmid with a synthetic cis-regulatory element upstream of a promoter driving a synthetic gene such as Green Fluorescent Protein. A library of cis-regulatory elements is usually tested using MPRAs, a library can contain from hundreds to thousands of cis-regulatory elements. The cis-regulatory activity of the elements is assayed by using the downstream reporter activity. The activity of all the library members is assayed in parallel using barcodes for each cis-regulatory element. One limitation of MPRAs is that the activity is assayed on a plasmid and may not capture all aspects of gene regulation observed in the genome. | 1 | Applied and Interdisciplinary Chemistry |
The detector (5) of AFM measures the deflection (displacement with respect to the equilibrium position) of the cantilever and converts it into an electrical signal. The intensity of this signal will be proportional to the displacement of the cantilever.
Various methods of detection can be used, e.g. interferometry, optical levers, the piezoelectric method, and STM-based detectors (see section "AFM cantilever deflection measurement"). | 0 | Theoretical and Fundamental Chemistry |
Referring back to the derivation for Darken's first equation, is written as
Inserting this value for in gives
As stated before, , which gives
Rewriting this equation in terms of atom fraction and yields
By using and solving to the form , it is found that
Integrating the above gives the final equation:
This equation is only applicable for binary systems that follow the equations of state and the Gibbs–Duhem equation. This equation, as well as Darken's first law, , gives a complete description of an ideal binary diffusion system. This derivation was the approach taken by Darken in his original 1948, though shorter methods can be used to attain the same result. | 0 | Theoretical and Fundamental Chemistry |
For surfaces which are not black bodies, one has to consider the (generally frequency dependent) emissivity factor . This factor has to be multiplied with the radiation spectrum formula before integration. If it is taken as a constant, the resulting formula for the power output can be written in a way that contains as a factor:
This type of theoretical model, with frequency-independent emissivity lower than that of a perfect black body, is often known as a grey body. For frequency-dependent emissivity, the solution for the integrated power depends on the functional form of the dependence, though in general there is no simple expression for it. Practically speaking, if the emissivity of the body is roughly constant around the peak emission wavelength, the gray body model tends to work fairly well since the weight of the curve around the peak emission tends to dominate the integral. | 0 | Theoretical and Fundamental Chemistry |
Other options besides traditional NMR spectroscopy for sequence analysis are listed here; these include Kerr-effect for characterization of polymer microstructures, MALDI-TOF mass spectrometry, depolymerization (controlled chemical degradation of macromolecules) via chain-end depolymerization (i.e., unzipping) and nanopore analysis (most of such reported studies, however, have focused on poly(ethylene glycol), PEG). | 0 | Theoretical and Fundamental Chemistry |
* 1997 Alexander von Humboldt Fellowship
* 1999 National Laboratory Visiting Fellow (NSERC)
* 2004 Fred Beamish Award (CSC)
* 2008 JSPS Invitation Fellow
* 2011 W. Lash Miller Award (ECS Canadian Section)
* 2012 Tajima Prize (ISE)
* 2015 W.A.E. McBryde Medal (CSC)
* 2021 Fellow, Royal Society of Chemistry | 0 | Theoretical and Fundamental Chemistry |
Paint has four major components: pigments, binders, solvents, and additives. Pigments serve to give paint its color, texture, toughness, as well as determining if a paint is opaque or not. Common white pigments include titanium dioxide and zinc oxide. Binders are the film forming component of a paint as it dries and affects the durability, gloss, and flexibility of the coating. Polyurethanes, polyesters, and acrylics are all examples of common binders. The solvent is the medium in which all other components of the paint are dissolved and evaporates away as the paint dries and cures. The solvent also modifies the curing rate and viscosity of the paint in its liquid state. There are two types of paint: solvent-borne and water-borne paints. Solvent-borne paints use organic solvents as the primary vehicle carrying the solid components in a paint formulation, whereas water-borne paints use water as the continuous medium. The additives that are incorporated into paints are a wide range of things which impart important effects on the properties of the paint and the final coating. Common paint additives are catalysts, thickeners, stabilizers, emulsifiers, texturizers, biocides to fight bacterial growth, etc.
The word surfactant is short for surface active agent. Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or the interfacial tension between a liquid and a solid. In solutions this behavior is known as wetting, and it occurs as a result of surfactants adsorbing to the air/water interface. Soluble surfactants are also capable of forming micelles and other aggregate structures in solution, leading to a stabilizing effect in latex paints. Surfactants in paint are used to change many end properties of a dried paint, as well as to emulsify paints in their liquid state. | 0 | Theoretical and Fundamental Chemistry |
From a study of lithium abundances in 53 T Tauri stars, it has been found that lithium depletion varies strongly with size, suggesting that lithium burning by the P-P chain, during the last highly convective and unstable stages during the pre–main sequence later phase of the Hayashi contraction may be one of the main sources of energy for T Tauri stars. Rapid rotation tends to improve mixing and increase the transport of lithium into deeper layers where it is destroyed. T Tauri stars generally increase their rotation rates as they age, through contraction and spin-up, as they conserve angular momentum. This causes an increased rate of lithium loss with age. Lithium burning will also increase with higher temperatures and mass, and will last for at most a little over 100 million years.
The P-P chain for lithium burning is as follows
It will not occur in stars less than sixty times the mass of Jupiter. In this way, the rate of lithium depletion can be used to calculate the age of the star. | 0 | Theoretical and Fundamental Chemistry |
The Edinburgh Handedness Inventory is a measurement scale used to assess the dominance of a person's right or left hand in everyday activities, sometimes referred to as laterality. The inventory can be used by an observer assessing the person, or by a person self-reporting hand use. The latter method tends to be less reliable due to a person over-attributing tasks to the dominant hand.
The Edinburgh Handedness Inventory was published in 1971 by Richard Carolus Oldfieldand has been used in various scientific studies as well as popular literature. According to Google Scholar it has been cited tens of thousands of times. Within the very substantial literature on handedness it is used far more than any rival, such as FLANDERS, or the Annett Hand Preference Questionnaire, which is not good at eliciting either-hand responses.
Nevertheless, profound dissatisfaction with the Inventory has been expressed and statistical analysis of the Inventory has shown that the two-handed items broom and box are poorly correlated with the other eight items, while drawing is too highly correlated with writing to add information. A major revision has been published. | 0 | Theoretical and Fundamental Chemistry |
The nucleosome core particle is the most basic form of DNA compaction in eukaryotes. Nucleosomes consist of a histone octamer surrounded by 146 base pairs of DNA wrapped in a superhelical manner. In addition to compacting the DNA, the histone octamer plays a key role in the transcription of the DNA surrounding it. The histone octamer interacts with the DNA through both its core histone folds and N-terminal tails. The histone fold interacts chemically and physically with the DNA's minor groove. Studies have found that the histones interact more favorably with A:T enriched regions than G:C enriched regions in the minor grooves. The N-terminal tails do not interact with a specific region of DNA but rather stabilize and guide the DNA wrapped around the octamer. The interactions between the histone octamer and DNA, however, are not permanent. The two can be separated quite easily and often are during replication and transcription. Specific remodeling proteins are constantly altering the chromatin structure by breaking the bonds between the DNA and nucleosome. | 1 | Applied and Interdisciplinary Chemistry |
Sapropelic deposits from global ocean anoxic events form important oil source rocks. Detailed process studies of sapropel formation have concentrated on the fairly recent eastern Mediterranean deposits, the last of which occurred between 9.5 and 5.5 thousand years ago.
The Mediterranean sapropels of the Pleistocene reflect increased density stratification in the isolated Mediterranean basin. They record a higher organic carbon concentration than non-sapropel times; an increase in the δN and corresponding decrease in δC tells of rising productivity as a result of nitrogen fixation. This effect is more pronounced further east in the basin, suggesting that increased precipitation was most pronounced at that end of the sea. | 0 | Theoretical and Fundamental Chemistry |
In chemistry an eclipsed conformation is a conformation in which two substituents X and Y on adjacent atoms A, B are in closest proximity, implying that the torsion angle X–A–B–Y is 0°. Such a conformation can exist in any open chain, single chemical bond connecting two sp-hybridised atoms, and it is normally a conformational energy maximum. This maximum is often explained by steric hindrance, but its origins sometimes actually lie in hyperconjugation (as when the eclipsing interaction is of two hydrogen atoms).
In order to gain a deeper understanding of eclipsed conformations in organic chemistry, it is first important to understand how organic molecules are arranged around bonds, as well as how they move and rotate.
In the example of ethane, two methyl groups are connected with a carbon-carbon sigma bond, just as one might connect two Lego pieces through a single “stud” and “tube”. With this image in mind, if the methyl groups are rotated around the bond, they will remain connected; however, the shape will change. This leads to multiple possible three-dimensional arrangements, known as conformations, conformational isomers (conformers), or sometimes rotational isomers (rotamers). | 0 | Theoretical and Fundamental Chemistry |
Matthaeus Silvaticus, Avicenna, Galen, Dioscorides, Platearius and Serapio inspired the appearance of three main works printed in Mainz: In 1484 the Herbarius, the following year the Gart der Gesundheit, and in 1491 the Ortus Sanitatis. The works contain 16, 242 and 570 references to Dioscorides, respectively.
The first appearance of Dioscorides as a printed book was a Latin translation printed at Colle, Italy by Johanemm Allemanun de Mdemblik in 1478. The Greek version appeared in 1499 by Manutius at Venice.
The most useful books of botany, pharmacy and medicine used by students and scholars were supplemented commentaries on Dioscorides, including the works of Fuchs, Anguillara, Mattioli, Maranta, Cesalpino, Dodoens, Fabius Columna, Gaspard and Johann Bauhin, and De Villanueva/Servetus. In several of these versions, the annotations and comments exceed the Dioscoridean text and have much new botany. Printers were not merely printing the authentic materia medica, but hiring experts on the medical and botanical field for criticism, commentaries, that would raise the stature of the printers and the work.
Most of these authors copied each other, from previous works. It was normal to add previous commentaries and marginalia, to make the text look more enriched or thorough.
There were several De Materia Medica works noted as Anonymous A, B, C and D by the expert on Dioscorides-De Materia Medica professor John M. Riddle. The Anonymous A has to do with authors on translations of handwriting. Riddle proved Anonymous C to be Bruyerinus Champier.
During the 16th century, the most representative among them were Ermolao Barbaro, Jean Ruel, Broyeurinus, Michel de Villeneuva, Pietro Andrea Mattioli, Andres Laguna, Marcello Virgilio, Martin Mathee and Valerius Cordus.
In 1789, William Cullen published his two volume A Treatise of the Materia Medica, which was highly valued by other medical practitioners throughout Europe. | 1 | Applied and Interdisciplinary Chemistry |
It reacts with tertiary amines to trisubstituted hydrazinium salts and with pyridine to the 1-amino pyridinium salt.
From 1-aminopyridinium salts the photochemically active 1-N-iminopyridinium ylides are accessible by acylation. The photochemical rearrangement of the obtained 1-N-iminipyridinium ylides leads in high yields to 1H-1,2-diazepines
N-amination of 1H-benzotriazole with hydroxylamine-O-sulfonic acid yields a mixture of 1-aminobenzotriazole (major product) and 2-aminobenzotriazole (minor product). From 1-aminotriazole, benzyne is formed in an almost quantitative yield by oxidation with lead(IV) acetate, which rapidly dimerizes to biphenylene in good yields.
Electron deficient heterocycles, such as tetrazole, can be N-aminated with hydroxylamine-O-sulfonic acid, while even more electron-deficient compounds, such as 5-nitrotetrazole, react only with stronger aminating agents such as O-tosylhydroxylamine or O- mesitylene sulfonylhydroxylamine to amino compounds, which were investigated as explosives.
In the N-amination of the unsubstituted tetrazole, a mixture of 1-amino- and 2-aminotetrazole is obtained.
Also sulfur compounds (such as thioethers) can be aminated with hydroxylamine-O-sulfonic acid to sulfinimines (isosteric with sulfoxides but far more unstable) or phosphorus compounds (such as triphenylphosphine) can be aminated to phosphine imides via the intermediate aminotriphenylphosphonium hydrogen sulfate.
The reaction of hydroxylamine-O-sulfonic acid with metal salts of sulfinic acids in sodium acetate solution produces primary sulfonamides in very good yields.
Diimine can formed in situ from hydroxylamine-O-sulfonic acid respectively hydroxylamine-O-sulfonic acid hydroxylamine sulfate mixtures, which hydrogenates selectively conjugated multiple bonds.[20] | 0 | Theoretical and Fundamental Chemistry |
When producers, importers or authorities test a sample for the unintended presence of GMOs, they usually do not know which GMO to expect. While EU authorities prefer an event-specific approach to this problem, US authorities rely on construct-specific test schemes. | 1 | Applied and Interdisciplinary Chemistry |
With the determination of the first structure of the complex between a G-protein coupled receptor (GPCR) and a G-protein trimer (Gαβγ) in 2011 a new chapter of GPCR research was opened for structural investigations of global switches with more than one protein being investigated. The previous breakthroughs involved determination of the crystal structure of the first GPCR, rhodopsin, in 2000 and the crystal structure of the first GPCR with a diffusible ligand (βAR) in 2007. The way in which the seven transmembrane helices of a GPCR are arranged into a bundle was suspected based on the low-resolution model of frog rhodopsin from cryogenic electron microscopy studies of the two-dimensional crystals. The crystal structure of rhodopsin, that came up three years later, was not a surprise apart from the presence of an additional cytoplasmic helix H8 and a precise location of a loop covering retinal binding site. However, it provided a scaffold which was hoped to be a universal template for homology modeling and drug design for other GPCRs – a notion that proved to be too optimistic.
Seven years later, the crystallization of β-adrenergic receptor (βAR) with a diffusible ligand brought surprising results because it revealed quite a different shape of the receptor extracellular side than that of rhodopsin. This area is important because it is responsible for the ligand binding and is targeted by many drugs. Moreover, the ligand binding site was much more spacious than in the rhodopsin structure and was open to the exterior. In the other receptors crystallized shortly afterwards the binding side was even more easily accessible to the ligand. New structures complemented with biochemical investigations uncovered mechanisms of action of molecular switches which modulate the structure of the receptor leading to activation states for agonists or to complete or partial inactivation states for inverse agonists.
The 2012 Nobel Prize in Chemistry was awarded to Brian Kobilka and Robert Lefkowitz for their work that was "crucial for understanding how G protein-coupled receptors function". There have been at least seven other Nobel Prizes awarded for some aspect of G protein–mediated signaling. As of 2012, two of the top ten global best-selling drugs (Advair Diskus and Abilify) act by targeting G protein-coupled receptors. | 1 | Applied and Interdisciplinary Chemistry |
This friction factor is one-fourth of the Darcy friction factor, so attention must be paid to note which one of these is meant in the "friction factor" chart or equation consulted. Of the two, the Fanning friction factor is the more commonly used by chemical engineers and those following the British convention.
The formulas below may be used to obtain the Fanning friction factor for common applications.
The Darcy friction factor can also be expressed as
where:
* is the shear stress at the wall
* is the density of the fluid
* is the flow velocity averaged on the flow cross section | 1 | Applied and Interdisciplinary Chemistry |
A single antigen can be thought of as a sequence of multiple overlapping epitopes. Many unique B cell clones may be able to bind to the individual epitopes. This imparts even greater multiplicity to the overall response. All of these B cells can become activated and produce large colonies of plasma cell clones, each of which can secrete up to 1000 antibody molecules against each epitope per second. | 1 | Applied and Interdisciplinary Chemistry |
An advantage of the microscope spectrometer is its ability to use microscope apertures to precisely control the area of sample analysis. Flat capillaries can be used for analyzing small liquid samples, up to about 10 micro-liters in volume. Quartz or mirror-based optics can be used for studying samples from the ultraviolet (UV), down to 200 nm, to the near infrared (NIR) up to 2100 nm. Samples that emit electromagnetic radiation via fluorescence, phosphorescence or photoluminescence when exposed to light, can be quantitatively investigated using a variety of excitation and barrier filters. A variety of observations can be made on samples of interest by using different illumination sources such as halogen, xenon, deuterium and mercury lamps. Plane polarized light can also be used for studying birefringent samples. | 0 | Theoretical and Fundamental Chemistry |
Combining the laws of Charles, Boyle and Gay-Lussac gives the combined gas law, which takes the same functional form as the ideal gas law says that the number of moles is unspecified, and the ratio of to is simply taken as a constant:
where is the pressure of the gas, is the volume of the gas, is the absolute temperature of the gas, and is a constant. When comparing the same substance under two different sets of conditions, the law can be written as | 0 | Theoretical and Fundamental Chemistry |
T4 bacteriophage uses anti-sigma factor to ruin the Escherichia coli polymerase in order that direct exclusive transcription of its own genes.
AsiA is an anti-sigma factor gene that is required for bacteriophage T4 to be developed). Which means that AsiA is an essential anti-sigma factor in bacteriophage. | 1 | Applied and Interdisciplinary Chemistry |
Saponification value or saponification number (SV or SN) represents the number of milligrams of potassium hydroxide (KOH) or sodium hydroxide (NaOH) required to saponify one gram of fat under the conditions specified. It is a measure of the average molecular weight (or chain length) of all the fatty acids present in the sample in form of triglycerides. The higher the saponification value, the lower the fatty acids average length, the lighter the mean molecular weight of triglycerides and vice versa. Practically, fats or oils with high saponification value (such as coconut and palm oil) are more suitable for soap making. | 0 | Theoretical and Fundamental Chemistry |
Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water pollution from raw sewage discharges. Sewage contains wastewater from households and businesses and possibly pre-treated industrial wastewater. There are a high number of sewage treatment processes to choose from. These can range from decentralized systems (including on-site treatment systems) to large centralized systems involving a network of pipes and pump stations (called sewerage) which convey the sewage to a treatment plant. For cities that have a combined sewer, the sewers will also carry urban runoff (stormwater) to the sewage treatment plant. Sewage treatment often involves two main stages, called primary and secondary treatment, while advanced treatment also incorporates a tertiary treatment stage with polishing processes and nutrient removal. Secondary treatment can reduce organic matter (measured as biological oxygen demand) from sewage, using aerobic or anaerobic biological processes. A so-called quarternary treatment step (sometimes referred to as advanced treatment) can also be added for the removal of organic micropollutants, such as pharmaceuticals. This has been implemented in full-scale for example in Sweden.
A large number of sewage treatment technologies have been developed, mostly using biological treatment processes. Design engineers and decision makers need to take into account technical and economical criteria of each alternative when choosing a suitable technology. Often, the main criteria for selection are: desired effluent quality, expected construction and operating costs, availability of land, energy requirements and sustainability aspects. In developing countries and in rural areas with low population densities, sewage is often treated by various on-site sanitation systems and not conveyed in sewers. These systems include septic tanks connected to drain fields, on-site sewage systems (OSS), vermifilter systems and many more. On the other hand, advanced and relatively expensive sewage treatment plants may include tertiary treatment with disinfection and possibly even a fourth treatment stage to remove micropollutants.
At the global level, an estimated 52% of sewage is treated. However, sewage treatment rates are highly unequal for different countries around the world. For example, while high-income countries treat approximately 74% of their sewage, developing countries treat an average of just 4.2%.
The treatment of sewage is part of the field of sanitation. Sanitation also includes the management of human waste and solid waste as well as stormwater (drainage) management. The term sewage treatment plant is often used interchangeably with the term wastewater treatment plant. | 1 | Applied and Interdisciplinary Chemistry |
In quantum mechanics, a repulsive state is an electronic state of a molecule for which there is no minimum in the potential energy. This means that the state is unstable and unbound since the potential energy smoothly decreases with the interatomic distance and the atoms repel one another. In such a state there are no discrete vibrational energy levels; instead, these levels form a continuum. This should not be confused with an excited state, which is a metastable electronic state containing a minimum in the potential energy, and may be short or long-lived.
When a molecule is excited by means such as UV/VIS spectroscopy it can undergo a molecular electronic transition: if such a transition brings the molecule into a repulsive state, it will spontaneously dissociate. This condition is also known as predissociation since the chemical bond is broken at an energy which is lower than what might be expected. In electronic spectroscopy, this often appears as a strong, continuous feature in the absorption or emission spectrum, making repulsive states easy to detect.
For example, triatomic hydrogen has a repulsive ground state, which means it can only exist in an excited state: if it drops down to the ground state, it will immediately break up into one of the several possible dissociation products. | 0 | Theoretical and Fundamental Chemistry |
Humans have between 10 and 20 million olfactory receptor neurons (ORNs). In vertebrates, ORNs are bipolar neurons with dendrites facing the external surface of the cribriform plate with axons that pass through the cribriform foramina with terminal end at olfactory bulbs. The ORNs are located in the olfactory epithelium in the nasal cavity. The cell bodies of the ORNs are distributed among all three of the stratified layers of the olfactory epithelium.
Many tiny hair-like non-motile cilia protrude from the olfactory receptor cell's dendrites. The dendrites extend to the olfactory epithelial surface and each ends in a dendritic knob from which around 20 to 35 cilia protrude. The cilia have a length of up to 100 micrometres and with the cilia from other dendrites form a meshwork in the olfactory mucus. The surface of the cilia is covered with olfactory receptors, a type of G protein-coupled receptor. Each olfactory receptor cell expresses only one type of olfactory receptor (OR), but many separate olfactory receptor cells express ORs which bind the same set of odors. The axons of olfactory receptor cells which express the same OR converge to form glomeruli in the olfactory bulb. | 1 | Applied and Interdisciplinary Chemistry |
In the 1970s, male musicians began to use makeup onstage. This included famous rock stars such as David Bowie, Alice Cooper, and the band Kiss. The use of cosmetics allowed them to create an alter ego, and were part of the visual entertainment of their shows. Currently, the popularity of TikTok has created a rise in men's cosmetics. Some men have chosen to wear nail polish, makeup, and other cosmetics to express their identity online. | 1 | Applied and Interdisciplinary Chemistry |
Particle size and surface area influence the drug absorption and subsequently the therapeutic action. The higher the dissolution, the faster the absorption and hence the quicker and greater the drug action. | 0 | Theoretical and Fundamental Chemistry |
Ractopamine () is an animal feed additive used to promote leanness and increase food conversion efficiency in farmed animals in several countries, but banned in others. Pharmacologically, it is a phenol-based TAAR1 agonist and β adrenoreceptor agonist that stimulates β and β adrenergic receptors.
It is most commonly administered to animals for meat production as ractopamine hydrochloride. It is the active ingredient in products marketed in the US as Paylean for swine, Optaflexx for cattle, and Topmax for turkeys. It was developed by Elanco Animal Health, a division of Eli Lilly and Company.
As of 2014, the use of ractopamine was banned in 160 countries, including the European Union, China and Russia, while 27 other countries, such as Japan, the United States, South Korea, and New Zealand have deemed meat from livestock fed ractopamine safe for human consumption.
Commercial ractopamine is a mixture of all four possible stereoisomers. It is also a positional isomer of dobutamine, a related drug. | 0 | Theoretical and Fundamental Chemistry |
White adipose tissue, also known as white fat, is one two types of adipose tissue in mammals. White adipose tissue stores energy in the form of triglycerides, which can be broken down to free fatty acids on demand. Its normal function is to store free fatty acids as triglycerides within the tissue. When glucose is deficient, in situations like fasting, white adipose tissue generates glycerol 3-phosphate. | 1 | Applied and Interdisciplinary Chemistry |
For its medical uses, 1,1,1,2-tetrafluoroethane has the generic name norflurane. It is used as propellant for some metered dose inhalers. It is considered safe for this use. In combination with pentafluoropropane, it is used as a topical vapocoolant spray for numbing boils before curettage. It has also been studied as a potential inhalational anesthetic, but it is nonanaesthetic at doses used in inhalers. | 1 | Applied and Interdisciplinary Chemistry |
Because of the carcinogenicity of its beta radiation in the thyroid in small doses, I-131 is rarely used primarily or solely for diagnosis (although in the past this was more common due to this isotope's relative ease of production and low expense). Instead the more purely gamma-emitting radioiodine iodine-123 is used in diagnostic testing (nuclear medicine scan of the thyroid). The longer half-lived iodine-125 is also occasionally used when a longer half-life radioiodine is needed for diagnosis, and in brachytherapy treatment (isotope confined in small seed-like metal capsules), where the low-energy gamma radiation without a beta component makes iodine-125 useful. The other radioisotopes of iodine are never used in brachytherapy.
The use of I as a medical isotope has been blamed for a routine shipment of biosolids being rejected from crossing the Canada—U.S. border. Such material can enter the sewers directly from the medical facilities, or by being excreted by patients after a treatment | 0 | Theoretical and Fundamental Chemistry |
P. rubens has four chromosomes. The genome of the Wisconsin strain has been most studied. The nuclear genome of 54-1255 strain, regarded as low-penicillin producer, has a size of 32.19 Mb. There are 13,653 open reading frames (ORFs), including 592 probable pseudogenes and 116 truncated ORFs. Three genes, namely pcbAB, pcbC, and penDE constitute the core sites for penicillin biosynthesis. They are distributed in clusters among other (ORFs) in a 58.8 kb region, on chromosome 2. pcbAB encodes an enzyme α-aminoadipoyl-L-cysteinyl-D-valine synthetase, pcbC encodes isopenicillinN (IPN) synthase, and penDE, encoding acyl-CoA:isopenicillinN acyltransferase. The high penicillin-producing strain, NCPC10086, has slightly larger genome of 32.3 Mb, with about 13,290 protein-coding genes. There are at least 69 genes not present in 54-1255 strain. The gene Pch018g00010 that codes for enzymes in glutathione metabolism is considered as the key factor in enhanced penicillin production of this strain.
The mitochondrial genome consists of 31,790 bp and 17 ORFs. Enzymes synthesised from the nuclear genome are not sufficient for complete synthesis of penicillin. Enzymes of the final biosynthetic pathway such as acyl-CoA:isopenicillinN acyltransferase28 and phenylacetyl-CoA ligase are synthesised in separate cell organelles called microbodies (peroxisomes). The peroxisome gene pex11 is essential for controlling the amount of penicillin synthesis; the more the gene is activated (expressed), the more the penicillins. | 1 | Applied and Interdisciplinary Chemistry |
The solution for the flow forming the bottom Ekman spiral was a result of the shear stress exerted on the flow by the bottom. Logically, wherever shear stress can be exerted on a flow, Ekman spirals will form. This is the case at the air–water interface, because of wind. A situation is considered where a wind stress is exerted along a water-surface with an interior flow beneath. Again, the flow is uniform, has a geostrophic interior and is homogeneous fluid. The equations of motion for a geostrophic flow, which are the same as stated in the bottom spiral section, can be reduced to:
The boundary conditions for this case are as follows:
* Surface : and
* Towards interior : and
With these conditions, the solution can be determined:
Some differences with respect to the bottom Ekman spiral emerge. The deviation from the interior flow is exclusively dependent on the wind stress and not on the interior flow. Whereas in the case of the bottom Ekman spiral, the deviation is determined by the interior flow. The wind-driven component of the flow is inversely proportional with respect to the Ekman-layer thickness . So if the layer thickness is small, because of a small viscosity of the fluid for example, this component could be very large. At last, the flow at the surface is 45 degrees to the right on the northern hemisphere and 45 degrees to the left on the southern hemisphere with respect to the wind-direction. In case of the bottom Ekman spiral, this is the other way around. | 1 | Applied and Interdisciplinary Chemistry |
Hemiaminal formation is a key step in an asymmetric total synthesis of saxitoxin:
In this reaction step the alkene group is first oxidized to an intermediate acyloin by action of osmium(III) chloride, oxone (sacrificial catalyst) and sodium carbonate (base). | 0 | Theoretical and Fundamental Chemistry |
The different stages of the method are lyse, bind, wash, and elute. More specifically, this entails the lysis of target cells to release nucleic acids, selective binding of nucleic acid to a silica membrane, washing away particulates and inhibitors that are not bound to the silica membrane, and elution of the nucleic acid, with the end result being purified nucleic acid in an aqueous solution.
For lysis, the cells (blood, tissue, etc.) of the sample must undergo a treatment to break the cell membrane and free the nucleic acid. Depending on the target material, this can include the use of detergent or other buffers, proteinases or other enzymes, heating to various times/temperatures, or mechanical disruption such as cutting with a knife or homogenizer, using a mortar and pestle, or bead-beating with a bead mill.
For binding, a buffer solution is then added to the lysed sample along with ethanol or isopropanol. The sample in binding solution is then transferred to a spin column, and the column is put either in a centrifuge or attached to a vacuum. The centrifuge/vacuum forces the solution through a silica membrane that is inside the spin column, where under the right ionic conditions, nucleic acids will bind to the silica membrane, as the rest of the solution passes through. With the target material bound, the flow-through can be removed.
To wash, a new buffer is added onto the column, then centrifuged/vacuumed through the membrane. This buffer is intended to maintain binding conditions, while removing the binding salts and other remaining contaminants. Generally it takes several washes, often with increasing percentages of ethanol/isopropanol, until the nucleic acid on the silica membrane is free of contaminants. The last wash is often a dry step to allow the alcohol to evaporate, leaving only purified nucleic acids bound to the column.
Finally, elution is the process of adding an aqueous solution to the column, allowing the hydrophilic nucleic acid to leave the column and return to solution. This step may be improved with salt, pH, time, or heat. Finally, to capture the eluate/eluent, the column is transferred into a clean microtube prior to a last centrifugation step. | 1 | Applied and Interdisciplinary Chemistry |
In premixed turbulent combustion, the Klimov–Williams criterion or Klimov–Williams limit, named after A.M. Klimov and Forman A. Williams, is the condition where (assuming a Schmidt number of unity). When , the flame thickness is smaller than the Kolmogorov scale, thus the flame burning velocity is not affected by the turbulence field. Here, the burning velocity is given by the laminar flame speed and these laminar flamelets are called as wrinkled flamelets or corrugated flamelets, depending on the turbulence intensity. When , the turbulent transport penetrates into the preheat zone of the flame (thin reaction zone) or even into the reactive-diffusive zone (distributed flames). | 0 | Theoretical and Fundamental Chemistry |
Anfinsens dogma, also known as the thermodynamic hypothesis, is a postulate in molecular biology. It states that, at least for a small globular protein in its standard physiological environment, the native structure is determined only by the proteins amino acid sequence. The dogma was championed by the Nobel Prize Laureate Christian B. Anfinsen from his research on the folding of ribonuclease A. The postulate amounts to saying that, at the environmental conditions (temperature, solvent concentration and composition, etc.) at which folding occurs, the native structure is a unique, stable and kinetically accessible minimum of the free energy. In other words, there are three conditions for formation of a unique protein structure:
*Uniqueness – Requires that the sequence does not have any other configuration with a comparable free energy. Hence the free energy minimum must be unchallenged.
*Stability – Small changes in the surrounding environment cannot give rise to changes in the minimum configuration. This can be pictured as a free energy surface that looks more like a funnel (with the native state in the bottom of it) rather than like a soup plate (with several closely related low-energy states); the free energy surface around the native state must be rather steep and high, in order to provide stability.
*Kinetical accessibility – Means that the path in the free energy surface from the unfolded to the folded state must be reasonably smooth or, in other words, that the folding of the chain must not involve highly complex changes in the shape (like knots or other high order conformations). Basic changes in the shape of the protein happen dependent on their environment, shifting shape to suit their place. This creates multiple configurations for biomolecules to shift into. | 1 | Applied and Interdisciplinary Chemistry |
There are two main types of ultrasonic flowmeters: Doppler and transit time. While they both utilize ultrasound to make measurements and can be non-invasive (measure flow from outside the tube, pipe or vessel, also called clamp-on device), they measure flow by very different methods.
Ultrasonic transit time flowmeters measure the difference of the transit time of ultrasonic pulses propagating in and against the direction of flow. This time difference is a measure for the average velocity of the fluid along the path of the ultrasonic beam. By using the absolute transit times both the averaged fluid velocity and the speed of sound can be calculated. Using the two transit times and and the distance between receiving and transmitting transducers and the inclination angle one can write the equations:
and
where is the average velocity of the fluid along the sound path and is the speed of sound.
With wide-beam illumination transit time ultrasound can also be used to measure volume flow independent of the cross-sectional area of the vessel or tube.
Ultrasonic Doppler flowmeters measure the Doppler shift resulting from reflecting an ultrasonic beam off the particulates in flowing fluid. The frequency of the transmitted beam is affected by the movement of the particles; this frequency shift can be used to calculate the fluid velocity. For the Doppler principle to work, there must be a high enough density of sonically reflective materials such as solid particles or air bubbles suspended in the fluid. This is in direct contrast to an ultrasonic transit time flowmeter, where bubbles and solid particles reduce the accuracy of the measurement. Due to the dependency on these particles, there are limited applications for Doppler flowmeters. This technology is also known as acoustic Doppler velocimetry.
One advantage of ultrasonic flowmeters is that they can effectively measure the flow rates for a wide variety of fluids, as long as the speed of sound through that fluid is known. For example, ultrasonic flowmeters are used for the measurement of such diverse fluids as liquid natural gas (LNG) and blood. One can also calculate the expected speed of sound for a given fluid; this can be compared to the speed of sound empirically measured by an ultrasonic flowmeter for the purposes of monitoring the quality of the flowmeter's measurements. A drop in quality (change in the measured speed of sound) is an indication that the meter needs servicing. | 1 | Applied and Interdisciplinary Chemistry |
Characterization and quantification of the transcriptome in a given "dead" tissue can identify genetic assets, which can be used to determine the regulatory mechanisms and set networks of gene expression.
The techniques commonly used for simultaneously measuring the concentration of a large number of different types of mRNA include microarrays and high-throughput sequencing via RNA-Seq.
Analysis from a serology postmortem can characterize the transcriptome of a particular tissue cell type, or compare the transcriptomes between various experimental conditions. Such analysis can be complementary to the analysis of thanatomicrobiome to better understand the process of transformation of the necromass in the hours and days following death. | 1 | Applied and Interdisciplinary Chemistry |
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