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To illustrate the difficulty of building a beam-target fusion system, we will consider one promising fusion fuel, the proton-boron cycle, or p-B11.
Boron can be formed into highly purified solid blocks, and protons easily produced by ionizing hydrogen gas. The protons can be accelerated and fired into the boron block, and the reactions will cause several alpha particles to be released. These can be collected in an electrostatic system to directly produce electricity without having to use a Rankine cycle or a similar heat-driven system. As the reactions create no neutrons directly, they have many practical advantages for safety also.
The chance of a collision is maximized when the protons have an energy of about 675 keV. When they fuse, the alphas carry away a total of 8.7 MeV. Some of that energy, 0.675 MeV, must be recycled into the accelerator to produce new protons to continue the process, and the generation and acceleration process is unlikely to be much more than 50% efficient. This still leaves ample net energy to close the cycle. However, this assumes every proton causes a fusion event, which does not occur. Considering the probability of a reaction, the resultant cycle is:
where and are the probabilities that any given proton or boron will undergo a reaction. Re-arranging, we can show that:
That means that to break even, the system needs at least of the particles to undergo fusion. To ensure that a proton has a chance to collide with a boron, it must travel past many boron atoms. The collision rate is:
where is the nuclear cross section between a proton and boron, is the density of boron, and is the average distance the proton travels through the boron before undergoing a fusion reaction. For p-B11, is 0.9 x 10 cm, is 2.535 g/cm, and thus ~ 8 cm. However, travelling through the block causes the proton to ionize the boron atoms it passes, which slows the proton. At 0.675 MeV, this process slows the proton to sub-keV energies in about 10 cm, many orders of magnitude less than what is required. | 0 | Theoretical and Fundamental Chemistry |
In the physical sciences, a partition coefficient (P) or distribution coefficient (D) is the ratio of concentrations of a compound in a mixture of two immiscible solvents at equilibrium. This ratio is therefore a comparison of the solubilities of the solute in these two liquids. The partition coefficient generally refers to the concentration ratio of un-ionized species of compound, whereas the distribution coefficient refers to the concentration ratio of all species of the compound (ionized plus un-ionized).
In the chemical and pharmaceutical sciences, both phases usually are solvents. Most commonly, one of the solvents is water, while the second is hydrophobic, such as 1-octanol. Hence the partition coefficient measures how hydrophilic ("water-loving") or hydrophobic ("water-fearing") a chemical substance is. Partition coefficients are useful in estimating the distribution of drugs within the body. Hydrophobic drugs with high octanol-water partition coefficients are mainly distributed to hydrophobic areas such as lipid bilayers of cells. Conversely, hydrophilic drugs (low octanol/water partition coefficients) are found primarily in aqueous regions such as blood serum.
If one of the solvents is a gas and the other a liquid, a gas/liquid partition coefficient can be determined. For example, the blood/gas partition coefficient of a general anesthetic measures how easily the anesthetic passes from gas to blood. Partition coefficients can also be defined when one of the phases is solid, for instance, when one phase is a molten metal and the second is a solid metal, or when both phases are solids. The partitioning of a substance into a solid results in a solid solution.
Partition coefficients can be measured experimentally in various ways (by shake-flask, HPLC, etc.) or estimated by calculation based on a variety of methods (fragment-based, atom-based, etc.).
If a substance is present as several chemical species in the partition system due to association or dissociation, each species is assigned its own K value. A related value, D, does not distinguish between different species, only indicating the concentration ratio of the substance between the two phases. | 0 | Theoretical and Fundamental Chemistry |
Matching involves a systematic comparison of a patient's clinical and demographic information against the eligibility criteria of various trials. Methods include:
* Manual: Healthcare providers or clinical trial coordinators manually review patient records and available trial criteria to identify potential matches. This might also include manually searching in clinical trial databases.
* Electronic health records (EHR). Some systems integrate with EHRs to automatically flag patients that may be eligible for trials based on their medical data. These systems may leverage machine learning, artificial intelligence or precision medicine methods to more effectively match patients to trials. These methods are faced with the challenge of overcoming the limitations of EHR records such as omissions and logging errors.
* Direct-to-patient services: Resources are specialized to support patients in finding clinical trials through online platforms, hotlines, and personalized support. | 1 | Applied and Interdisciplinary Chemistry |
As mentioned above, a diathermal wall may pass energy as heat by thermal conduction, but not the matter. A diathermal wall can move and thus be a part of a transfer of energy as work. Amongst walls that are impermeable to matter, diathermal and adiabatic walls are contraries.
For radiation, some further comments may be useful.
In classical thermodynamics, one-way radiation, from one system to another, is not considered. Two-way radiation between two systems is one of the two mechanisms of transfer of energy as heat. It may occur across a vacuum, with the two systems separated from the intervening vacuum by walls that are permeable only to radiation; such an arrangement fits the definition of a diathermal wall. The balance of radiative transfer is transfer of heat.
In thermodynamics, it is not necessary that the radiative transfer of heat be of pure black-body radiation, nor of incoherent radiation. Of course black-body radiation is incoherent. Thus laser radiation counts in thermodynamics as a one-way component of two-way radiation that is heat transfer. Also, by the [Helmholtz reciprocity] principle, the target system radiates into the laser source system, though of course relatively weakly compared with the laser light. According to Planck, an incoherent monochromatic beam of light transfers entropy and has a temperature. For a transfer to qualify as work, it must be reversible in the surroundings, for example in the concept of a reversible work reservoir. Laser light is not reversible in the surroundings and is therefore a component of transfer of energy as heat, not work.
In radiative transfer theory, one-way radiation is considered. For investigation of Kirchhoff's law of thermal radiation the notions of absorptivity and emissivity are necessary, and they rest on the idea of one-way radiation. These things are important for the study of the Einstein coefficients, which relies partly on the notion of thermodynamic equilibrium.
For the thermodynamic stream of thinking, the notion of empirical temperature is coordinately presupposed in the notion of heat transfer for the definition of an adiabatic wall.
For the mechanical stream of thinking, the exact way in which the walls are defined is important.
In the presentation of Carathéodory, it is essential that the definition of the adiabatic wall should in no way depend upon the notions of heat or temperature. This is achieved by careful wording and reference to transfer of energy only as work. Buchdahl is careful in the same way. Nevertheless, Carathéodory explicitly postulates the existence of walls that are permeable only to heat, that is to say impermeable to work and to matter, but still permeable to energy in some unspecified way; they are called diathermal walls. One might be forgiven for inferring from this that heat is energy in transfer across walls permeable only to heat, and that such are admitted to exist unlabeled as postulated primitives.
The mechanical stream of thinking thus regards the adiabatic enclosure's property of not allowing the transfer of heat across itself as a deduction from the Carathéodory axioms of thermodynamics, and regards transfer as heat as a residual rather than a primary concept. | 0 | Theoretical and Fundamental Chemistry |
The town owners constructed a single-track standard-gauge steam railway to get products and supplies to and from Cement and Tolenas which were away from each other. The company had a total of of track including yard and side tracks. The railway's name was . | 1 | Applied and Interdisciplinary Chemistry |
Much like beta-oxidation, straight-chain fatty acid synthesis occurs via the six recurring reactions shown below, until the 16-carbon palmitic acid is produced.
The diagrams presented show how fatty acids are synthesized in microorganisms and list the enzymes found in Escherichia coli. These reactions are performed by fatty acid synthase II (FASII), which in general contains multiple enzymes that act as one complex. FASII is present in prokaryotes, plants, fungi, and parasites, as well as in mitochondria.
In animals as well as some fungi such as yeast, these same reactions occur on fatty acid synthase I (FASI), a large dimeric protein that has all of the enzymatic activities required to create a fatty acid. FASI is less efficient than FASII; however, it allows for the formation of more molecules, including "medium-chain" fatty acids via early chain termination. Enzymes, acyltransferases and transacylases, incorporate fatty acids in phospholipids, triacylglycerols, etc. by transferring fatty acids between an acyl acceptor and donor. They also have the task of synthesizing bioactive lipids as well as their precursor molecules.
Once a 16:0 carbon fatty acid has been formed, it can undergo a number of modifications, resulting in desaturation and/or elongation. Elongation, starting with stearate (18:0), is performed mainly in the endoplasmic reticulum by several membrane-bound enzymes. The enzymatic steps involved in the elongation process are principally the same as those carried out by fatty acid synthesis, but the four principal successive steps of the elongation are performed by individual proteins, which may be physically associated.
Abbreviations: ACP – Acyl carrier protein, CoA – Coenzyme A, NADP – Nicotinamide adenine dinucleotide phosphate.
Note that during fatty synthesis the reducing agent is NADPH, whereas NAD is the oxidizing agent in beta-oxidation (the breakdown of fatty acids to acetyl-CoA). This difference exemplifies a general principle that NADPH is consumed during biosynthetic reactions, whereas NADH is generated in energy-yielding reactions. (Thus NADPH is also required for the synthesis of cholesterol from acetyl-CoA; while NADH is generated during glycolysis.) The source of the NADPH is two-fold. When malate is oxidatively decarboxylated by “NADP-linked malic enzyme" pyruvate, CO and NADPH are formed. NADPH is also formed by the pentose phosphate pathway which converts glucose into ribose, which can be used in synthesis of nucleotides and nucleic acids, or it can be catabolized to pyruvate. | 1 | Applied and Interdisciplinary Chemistry |
Iodine and thyroxine have also been shown to stimulate the spectacular apoptosis of the cells of the larval gills, tail and fins during metamorphosis in amphibians, as well as the transformation of their nervous system from that of the aquatic, herbivorous tadpole into that of the terrestrial, carnivorous adult. The frog species Xenopus laevis has proven to be an ideal model organism for experimental study of the mechanisms of apoptosis and the role of iodine in developmental biology. | 1 | Applied and Interdisciplinary Chemistry |
Yuri Tsolakovich Oganessian ( ; , born 14 April 1933) is a Soviet, Armenian and Russian nuclear physicist who is best known as a researcher of superheavy chemical elements. He participated with the discovery of multiple elements of the periodic table. He succeeded Georgy Flyorov as director of the Flyorov Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research in 1989 and is now its scientific director. The heaviest element known of the periodic table, oganesson, is named after him, only the second time that an element was named after a living person (the other being seaborgium). | 1 | Applied and Interdisciplinary Chemistry |
The recovery and beneficiation of glass products produced via reuse or reprocessing of glass found in municipal wastes are very important goals from the environmental and economic point of view. Some technologies allow not only to reduce the volume of landfill waste but also to generate products of economic value by reuse, recycling and recorporation in manufacturing processes. Some of the recycling products from glass are; glass ceramics, slag, fly ash & bottom ash are known as secondary raw materials. Mixed with glass cullet, bottom ash can be easily transformed into homogeneous and inert glasses, which can be transformed into glass fibres or sintered glass-ceramics after controlled thermal treatments. Alternatively, bottom ash can be used to produce tiles, in particular glazed tiles containing vitrified bottom ash in the ceramic body, and possibly bricks. This work will however focus on the use of glass as a secondary material in construction industry. | 0 | Theoretical and Fundamental Chemistry |
While mouse and human antibodies are structurally similar, the differences between them were sufficient to invoke an immune response when murine monoclonal antibodies were injected into humans, resulting in their rapid removal from the blood, as well as systemic inflammatory effects and the production of human anti-mouse antibodies (HAMA).
Recombinant DNA has been explored since the late 1980s to increase residence times. In one approach called "CDR grafting", mouse DNA encoding the binding portion of a monoclonal antibody was merged with human antibody-producing DNA in living cells. The expression of this "chimeric" or "humanised" DNA through cell culture yielded part-mouse, part-human antibodies. | 1 | Applied and Interdisciplinary Chemistry |
The L-alanine derivative β-methylamino-L-alanine (BMAA) has long been identified as a neurotoxin which was first associated with the amyotrophic lateral sclerosis/parkinsonism–dementia complex (Lytico-bodig disease) in the Chamorro people of Guam. The widespread occurrence of BMAA can be attributed to cyanobacteria which produce BMAA as a result of complex reactions under nitrogen stress. Following research, excitotoxicity appears to be the likely mode of action for BMAA which acts as a glutamate agonist, activating AMPA and NMDA receptors and causing damage to cells even at relatively low concentrations of 10 μM. The subsequent uncontrolled influx of Ca then leads to the pathophysiology described above. Further evidence of the role of BMAA as an excitotoxin is rooted in the ability of NMDA antagonists like MK801 to block the action of BMAA. More recently, evidence has been found that BMAA is misincorporated in place of L-serine in human proteins. A considerable portion of the research relating to the toxicity of BMAA has been conducted on rodents. A study published in 2016 with vervets (Chlorocebus sabaeus) in St. Kitts, which are homozygous for the apoE4 (APOE-ε4) allele (a condition which in humans is a risk factor for Alzheimers disease), found that vervets orally administered BMAA developed hallmark histopathology features of Alzheimers Disease including amyloid beta plaques and neurofibrillary tangle accumulation. Vervets in the trial fed smaller doses of BMAA were found to have correlative decreases in these pathology features. This study demonstrates that BMAA, an environmental toxin, can trigger neurodegenerative disease as a result of a gene/environment interaction. While BMAA has been detected in brain tissue of deceased ALS/PDC patients, further insight is required to trace neurodegenerative pathology in humans to BMAA. | 1 | Applied and Interdisciplinary Chemistry |
As highly reduced species in solution, Zintl ions offer many and often unexpected, reaction possibilities, and their discrete nature positions them as potentially important starting materials in inorganic synthesis.
In solution, individual Zintl ions can react with each other to form oligomers and polymers. In fact, anions with high nuclearity can be viewed as oxidative coupling products of monomers. After oxidation, the clusters may sometimes persist as radicals that can be used as precursors in other reactions. Zintl ions can oxidize without the presence of specific oxidizing agents through solvent molecules or impurities, for example in the presence of cryptand, which is often used to aid crystallization.
Zintl ion clusters can be functionalized with a variety of ligands in a similar reaction to their oligomerization. As such, functionalization competes with those reactions and both can be observed to occur. Organic groups, for example phenyl, TMS, and bromomethane, form exo bonds to the electronegative main group atoms. These ligands can also stabilize high nuclearity clusters, in particular heteroatomic examples.
Similarly in solids, Zintl phases can incorporate hydrogen. Such Zintl phase hydrides can be either formed by direct synthesis of the elements or element hydrides in a hydrogen atmosphere or by a hydrogenation reaction of a pristine Zintl phase. Since hydrogen has a comparable electronegativity as the post-transition metal it is incorporated as part of the polyanionic spatial structure. There are two structural motifs present. A monatomic hydride can be formed occupying an interstitial site that is coordinated by cations exclusively (interstitial hydride) or it can bind covalently to the polyanion (polyanionic hydride).
The Zintl ion itself can also act as a ligand in transition metal complexes. This reactivity is usually seen in clusters composed of greater than 9 atoms, and it is more common for group 15 clusters. A change in geometry often accompanies complexation; however zero electrons are contributed from the metal to the complex, so the electron count with respect to Wade's rules does not change. In some cases the transition metal will cap the face of the cluster. Another mode of reaction is the formation of endohedral complexes where the metal is encapsulated inside the cluster. These types of complexes lend themselves to comparison with the solid state structure of the corresponding Zintl phase. These reactions tend to be unpredictable and highly dependent on temperature, among other reaction conditions. | 0 | Theoretical and Fundamental Chemistry |
The first reaction of iodine with SO and water is as follows:
SO+I+2HO→HSO+2HI
As the reaction proceeds, all available SO will be consumed and the starch indicator added to the solution will bind with the unconsumed iodine, turning the solution black.
The second step of the reaction requires pretreating with solution with NaOH to release bound SO. The reaction with iodine can then be done.
HSO⇌HSO⇌SO | 0 | Theoretical and Fundamental Chemistry |
Hydrogen sulfide (HS) is a weak electrolyte. It is partially ionized when in aqueous solution, therefore there exists an equilibrium between un-ionized molecules and constituent ions in an aqueous medium as follows:
:HS H + HS
By applying the law of mass action, we have
Hydrochloric acid (HCl) is a strong electrolyte, which nearly completely ionizes as
:HCl → H + Cl
If HCl is added to the HS solution, H a common ion and creates a common ion effect. Due to the increase in concentration of H ions from the added HCl, the equilibrium of the dissociation of HS shifts to the left and keeps the value of K constant. Thus the dissociation of HS decreases, the concentration of un-ionized HS increases, and as a result, the concentration of sulfide ions decreases. | 0 | Theoretical and Fundamental Chemistry |
Vectors and planes in a crystal lattice are described by the three-value Miller index notation. This syntax uses the indices h, k, and ℓ as directional parameters.
By definition, the syntax (hkℓ) denotes a plane that intercepts the three points a/h, a/k, and a/ℓ, or some multiple thereof. That is, the Miller indices are proportional to the inverses of the intercepts of the plane with the unit cell (in the basis of the lattice vectors). If one or more of the indices is zero, it means that the planes do not intersect that axis (i.e., the intercept is "at infinity"). A plane containing a coordinate axis is translated so that it no longer contains that axis before its Miller indices are determined. The Miller indices for a plane are integers with no common factors. Negative indices are indicated with horizontal bars, as in (13). In an orthogonal coordinate system for a cubic cell, the Miller indices of a plane are the Cartesian components of a vector normal to the plane.
Considering only (hkℓ) planes intersecting one or more lattice points (the lattice planes), the distance d between adjacent lattice planes is related to the (shortest) reciprocal lattice vector orthogonal to the planes by the formula | 0 | Theoretical and Fundamental Chemistry |
Due to the biological complexity of gene expression, the considerations of experimental design that are discussed in the expression profiling article are of critical importance if statistically and biologically valid conclusions are to be drawn from the data.
There are three main elements to consider when designing a microarray experiment. First, replication of the biological samples is essential for drawing conclusions from the experiment. Second, technical replicates (e.g. two RNA samples obtained from each experimental unit) may help to quantitate precision. The biological replicates include independent RNA extractions. Technical replicates may be two aliquots of the same extraction. Third, spots of each cDNA clone or oligonucleotide are present as replicates (at least duplicates) on the microarray slide, to provide a measure of technical precision in each hybridization. It is critical that information about the sample preparation and handling is discussed, in order to help identify the independent units in the experiment and to avoid inflated estimates of statistical significance. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a leaving group is defined by the IUPAC as an atom or group of atoms that detaches from the main or residual part of a substrate during a reaction or elementary step of a reaction. However, in common usage, the term is often limited to a fragment that departs with a pair of electrons in heterolytic bond cleavage. In this usage, a leaving group is a less formal but more commonly used synonym of the term nucleofuge. In this context, leaving groups are generally anions or neutral species, departing from neutral or cationic substrates, respectively, though in rare cases, cations leaving from a dicationic substrate are also known.
A species' ability to serve as a leaving group depends on its ability to stabilize the additional electron density that results from bond heterolysis. Common anionic leaving groups are halides such as and , and sulfonate esters such as tosylate (), while water (), alcohols (), and amines () are common neutral leaving groups.
In the broader IUPAC definition, the term also includes groups that depart without an electron pair in a heterolytic cleavage (groups specifically known as an electrofuges), like or , which commonly depart in electrophilic aromatic substitution reactions. Similarly, species of high thermodynamic stability like nitrogen () or carbon dioxide () commonly act as leaving groups in homolytic bond cleavage reactions of radical species. A relatively uncommon term that serves as the antonym of leaving group is entering group (i.e., a species that reacts with and forms a bond with a substrate or a substrate-derived intermediate).
In this article, the discussions below mainly pertain to leaving groups that act as nucleofuges. | 0 | Theoretical and Fundamental Chemistry |
* 2000 Royal Society of Chemistry Meldola Medal and Prize
* 2018 Ramsay Trustee of the Society of Chemical Industry
* 2019 Royal Society of Chemistry Applied Inorganic Chemistry Award | 0 | Theoretical and Fundamental Chemistry |
Lecithins have emulsification and lubricant properties, and are a surfactant. They can be completely metabolized (see inositol) by humans, so are well tolerated by humans and nontoxic when ingested.
The major components of commercial soybean-derived lecithin are:
* 33–35% soybean oil
* 20–21% phosphatidylinositols
* 19–21% phosphatidylcholine
* 8–20% phosphatidylethanolamine
* 5–11% other phosphatides including phosphatidylserine
* 5% free carbohydrates
* 2–5% sterols
* 1% moisture
Lecithin is used for applications in human food, animal feed, pharmaceuticals, paints, and other industrial applications.
Applications include:
* In the pharmaceutical industry, it acts as a wetting agent, stabilizing agent and a choline enrichment carrier, helps in emulsification and encapsulation, and is a good dispersing agent. It can be used in manufacture of intravenous fat infusions and for therapeutic use.
* In animal feed, it enriches fat and protein and improves pelletization.
* In the paint industry, it forms protective coatings for surfaces with painting and printing ink, helps as a rust inhibitor, is a colour intensifying agent, catalyst, conditioning aid modifier, and dispersing aid; it is a good stabilizing and suspending agent, emulsifier, and wetting agent, helps in maintaining uniform mixture of several pigments, helps in grinding of metal oxide pigments, is a spreading and mixing aid, prevents hard settling of pigments, eliminates foam in water-based paints, and helps in fast dispersion of latex-based paints.
* Lecithin also may be used as a release agent for plastics, an anti-sludge additive in motor lubricants, an anti-gumming agent in gasoline, and an emulsifier, spreading agent, and antioxidant in textile, rubber, and other industries. | 0 | Theoretical and Fundamental Chemistry |
Like any mechanical and physical entity there are scientific, industrial, and layman terminology. The following is a partial list of terms that are associated with mechanical screening.
*Amplitude - This is a measurement of the screen cloth as it vertically peaks to its tallest height and troughs to its lowest point. Measured in multiples of the acceleration constant g (g-force).
*Acceleration - Applied Acceleration to the screen mesh in order to overcome the van der waal forces
*Blinding - When material plugs into the open slots of the screen cloth and inhibits overflowing material from falling through.
*Brushing - This procedure is performed by an operator who uses a brush to brush over the screen cloth to dislodged blinded opening.
*Contamination - This is unwanted material in a given grade. This occurs when there is oversize or fine size material relative to the cut or grade. Another type of contamination is foreign body contamination.
**Oversize contamination occurs when there is a hole in the screen such that the hole is larger than the mesh size of the screen. Other instances where oversize occurs is material overflow falling into the grade from overhead, or there is the wrong mesh size screen in place.
**Fines contamination is when large sections of the screen cloth is blinded over, and material flowing over the screen does not fall through. The fines are then retained in the grade.
**Foreign body contamination is unwanted material that differs from the virgin material going over and through the screen. It can be anything ranging from tree twigs, grass, metal slag to other mineral types and composition. This contamination occurs when there is a hole in the scalping screen or a foreign material's mineralogy or chemical composition differs from the virgin material.
*Deck - a deck is frame or apparatus that holds the screen cloth in place. It also contains the screening drive. It can contain multiple sections as the material travels from the feed end to the discharge end. Multiple decks are screen decks placed in a configuration where there are a series of decks attached vertically and lean at the same angle as it preceding and exceeding decks. Multiple decks are often referred to as single deck, double deck, triple deck, etc.
*Frequency - Measured in hertz (Hz) or revolutions per minute (RPM). Frequency is the number of times the screen cloth sinusoidally peaks and troughs within a second. As for a gyratory screening motion it is the number of revolutions the screens or screen deck takes in a time interval, such as revolution per minute (RPM).
*Gradation, grading - Also called "cut" or "cutting." Given a feed material in an initial state, the material can be defined to have a particle size distribution. Grading is removing the maximum size material and minimum size material by way of mesh selection.
*Screen Media (Screen cloth) - it is the material defined by mesh size, which can be made of any type of material such steel, stainless steel, rubber compounds, polyurethane, brass, etc.
*Shaker - the whole assembly of any type mechanical screening machine.
*Stratification - This phenomenon occurs as vibration is passed through a bed of material. This causes coarse (larger) material to rise and finer (smaller) material to descend within the bed. The material in contact with screen cloth either falls through a slot or blinds the slot or contacts the cloth material and is thrown from the cloth to fall to the next lower level.
*Mesh - The number of open slots per linear inch. Mesh is arranged in multiple configuration. Mesh can be a square pattern, long-slotted rectangular pattern, circular pattern, or diamond pattern.
*Scalp, scalping - this is the very first cut of the incoming material with the sum of all its grades. Scalping is removing the largest size particles. This includes enormously large particles relative to the other particle's sizes. Scalping also cleans the incoming material from foreign body contamination such as twigs, trash, glass, or other unwanted oversize material. | 1 | Applied and Interdisciplinary Chemistry |
In photosynthetic organisms, Mg has the additional vital role of being the coordinating ion in the chlorophyll molecule. This role was discovered by Richard Willstätter, who received the Nobel Prize in Chemistry 1915 for the purification and structure of chlorophyll binding with sixth number of carbon | 1 | Applied and Interdisciplinary Chemistry |
Nitrile oxides have the chemical formula . Their general structure is . The R stands for any group (typically organyl, e.g., acetonitrile oxide , hydrogen in the case of fulminic acid , or halogen, e.g., chlorine fulminate ). They and are used in 1,3-dipolar cycloadditions. They undergo type 1 dyotropic rearrangement to isocyanates. Nitrile oxides can be synthesised by dehydrogenation of oximes or by dehydration of nitroalkanes. They can be used to synthesise isoxazoles. | 0 | Theoretical and Fundamental Chemistry |
Drug solubility has previously been done by the shaker method. A 96-well high throughput device has allowed development of a new method to test drugs. | 0 | Theoretical and Fundamental Chemistry |
Some sperm banks enable recipients to choose the sex of their child, through methods of sperm sorting. Although the methods used do not guarantee 100% success, the chances of being able to select the gender of a child are held to be considerably increased.
One of the processes used is the swim up method, whereby a sperm extender is added to the donor's freshly ejaculated sperm and the test-tube is left to settle. After about half-an-hour, the lighter sperm, containing the male chromosome pair (XY), will have swum to the top, leaving the heavier sperm, containing the female chromosome pair (XX), at the bottom, thus allowing selection and storage according to sex.
The alternative process is the Percoll Method which is similar to the swim up method but involves additionally the centrifuging of the sperm in a similar way to the washing of samples produced for IUI inseminations, or for IVF purposes.
Sex selection is not permitted in a number of countries, including the UK. | 1 | Applied and Interdisciplinary Chemistry |
Another way to form primitive compartments that may lead to the formation of a protocell is polyesters membraneless structures that have the ability to host biochemicals (proteins and RNA) and/or scaffold the assemblies of lipids around them. While these droplets are leaky towards genetic materials, this leakiness could have facilitated the progenote hypothesis. | 0 | Theoretical and Fundamental Chemistry |
Conducting clinical trials of vaccines during epidemics and pandemics is subject to ethical concerns. For diseases with high mortality rates like Ebola, assigning individuals to a placebo or control group can be viewed as a death sentence. In response to ethical concerns regarding clinical research during epidemics, the National Academy of Medicine authored a report identifying seven ethical and scientific considerations. These considerations are:
* Scientific value
* Social value
* Respect for persons
* Community engagement
* Concern for participant welfare and interests
* A balance towards benefit over risks
* Post-trial access to tested therapies that had been withheld during the trial | 1 | Applied and Interdisciplinary Chemistry |
From the start Fulmer was a commercial enterprise aiming to make a surplus for investment in its own development. It received no grant or membership fees. Its income was solely from projects, each with defined objectives and time and cost limits agreed with individual sponsors from Government or Industry. Normally, the project contract would provide that all results would belong in confidence to the sponsor, who would also own any patents arising from the investigation. | 1 | Applied and Interdisciplinary Chemistry |
In the cells, the cytosolic CK enzymes consist of two subunits, which can be either B (brain type) or M (muscle type). There are, therefore, three different isoenzymes: CK-MM, CK-BB and CK-MB. The genes for these subunits are located on different chromosomes: B on 14q32 and M on 19q13. In addition to those three cytosolic CK isoforms, there are two mitochondrial creatine kinase isoenzymes, the ubiquitous form and the sarcomeric form. The functional entity of the mitochondrial CK isoforms is an octamer consisting of four dimers each.
While mitochondrial creatine kinase is directly involved in the formation of phosphocreatine from mitochondrial ATP, cytosolic CK regenerates ATP from ADP, using PCr. This happens at intracellular sites where ATP is used in the cell, with CK acting as an in situ ATP regenerator.
Isoenzyme patterns differ in tissues. Skeletal muscle expresses CK-MM (98%) and low levels of CK-MB (1%). The myocardium (heart muscle), in contrast, expresses CK-MM at 70% and CK-MB at 25–30%. CK-BB is predominantly expressed in brain and smooth muscle, including vascular and uterine tissue. | 1 | Applied and Interdisciplinary Chemistry |
Before powered fans were widely accessible, their use related to the social divide between social classes. In Britain and China, they were initially only installed in the buildings of Parliament and in noble homes. In Ancient Egypt (3150 BC), servants were required to fan Pharaohs and important figures.
In parts of the world such as India, where the temperature reaches above , standing and electric box fans are essential in the business world for customer comfort and an efficient work environment. Fans have become solar powered, energy efficient and battery powered in places with unreliable energy sources.
In South Korea, fans play a part in an old wives tale. Many older South Korean citizens believe in the unscientific and unsupported myth of fan death due to excessive use of an electric fan; Korean electric fans usually turn off after a few hours to protect from fan death.
Typical room electrical fans consume 50 to 100 watts of power, while air-conditioning units use 500 to 4000 watts; fans use less electricity but do not cool the air, simply providing evaporative cooling of sweat. Commercial fans are louder than AC units and can be to disruptively loud. According to the U.S. Consumer Product Safety Commission, reported incidents related to box fans include, fire (266 incidents), potential fire (29 incidents), electrocution (15), electric shock (4 incidents), and electrical hazard (2 incidents). Injuries related to AC units mostly relate to their falling from buildings. | 0 | Theoretical and Fundamental Chemistry |
Figuratively speaking, hyperspectral sensors collect information as a set of images. Each image represents a narrow wavelength range of the electromagnetic spectrum, also known as a spectral band. These images are combined to form a three-dimensional (x,y,λ) hyperspectral data cube for processing and analysis, where x and y represent two spatial dimensions of the scene, and λ represents the spectral dimension (comprising a range of wavelengths).
Technically speaking, there are four ways for sensors to sample the hyperspectral cube: Spatial scanning, spectral scanning, snapshot imaging, and spatio-spectral scanning.
Hyperspectral cubes are generated from airborne sensors like NASAs Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), or from satellites like NASAs EO-1 with its hyperspectral instrument Hyperion. However, for many development and validation studies, handheld sensors are used.
The precision of these sensors is typically measured in spectral resolution, which is the width of each band of the spectrum that is captured. If the scanner detects a large number of fairly narrow frequency bands, it is possible to identify objects even if they are only captured in a handful of pixels. However, spatial resolution is a factor in addition to spectral resolution. If the pixels are too large, then multiple objects are captured in the same pixel and become difficult to identify. If the pixels are too small, then the intensity captured by each sensor cell is low, and the decreased signal-to-noise ratio reduces the reliability of measured features.
The acquisition and processing of hyperspectral images is also referred to as imaging spectroscopy or, with reference to the hyperspectral cube, as 3D spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
The technique initially incubates a small amount of abnormal prion with an excess of normal protein, so that some conversion takes place. The growing chain of misfolded protein is then blasted with ultrasound, breaking it down into smaller chains and so rapidly increasing the amount of abnormal protein available to cause conversions. By repeating the cycle, the mass of normal protein is rapidly changed into the prion being tested for. | 1 | Applied and Interdisciplinary Chemistry |
* U.S. Naval Research Laboratory ocean-floor pressure sensors detected a freak wave caused by Hurricane Ivan in the Gulf of Mexico, 2004. The wave was around high from peak to trough, and around long. Their computer models also indicated that waves may have exceeded in the eyewall.
* Aleutian Ballad, (Bering Sea, 2005) footage of what is identified as an wave appears in an episode of Deadliest Catch. The wave strikes the ship at night and cripples the vessel, causing the boat to tip for a short period onto its side. This is one of the few video recordings of what might be a rogue wave.
* In 2006, researchers from U.S. Naval Institute theorized rogue waves may be responsible for the unexplained loss of low-flying aircraft, such as U.S. Coast Guard helicopters during search-and-rescue missions.
* MS Louis Majesty (Mediterranean Sea, March 2010) was struck by three successive waves while crossing the Gulf of Lion on a Mediterranean cruise between Cartagena and Marseille. Two passengers were killed by flying glass when the second and third waves shattered a lounge window. The waves, which struck without warning, were all abnormally high in respect to the sea swell at the time of the incident.
* In 2011, the Sea Shepherd vessel MV Brigitte Bardot was damaged by a rogue wave of 11 m (36.1 ft) while pursuing the Japanese whaling fleet off the western coast of Australia on 28 December 2011. The MV Brigitte Bardot was escorted back to Fremantle by the SSCS flagship, MV Steve Irwin. The main hull was cracked, and the port side pontoon was being held together by straps. The vessel arrived at Fremantle Harbor on 5 January 2012. Both ships were followed by the ICR security vessel MV Shōnan Maru 2 at a distance of 5 nautical miles (9 km).
* In 2019, Hurricane Dorian's extratropical remnant generated a rogue wave off the coast of Newfoundland.
* In 2022, the Viking cruise ship Viking Polaris was hit by a rogue wave on its way to Ushuaia, Argentina. One person died, four more were injured, and the ship's scheduled route to Antarctica was canceled. | 1 | Applied and Interdisciplinary Chemistry |
Around 1950, researchers from the Technion Institute in Haifa (Israel) and from New York University tried to explain this effect scientifically. In fact, there are two phenomena that contribute to this effect: on the one hand, the Bernoulli equation is used to explain it, on the other hand, the adhesion between the liquid and the spout material is also important.
According to the Bernoulli explanation, the liquid is pressed against the inner edge of the spout when pouring out, because the pressure conditions at the end, the edge, change significantly; the surrounding air pressure pushes the liquid towards the spout. With the help of a suitable pot geometry (or a sufficiently high pouring speed) it can be avoided that the liquid reaches the spout and thus triggers the teapot effect. Laws of hydrodynamics (flow theory) describe this situation, the relevant ones are explained in the following sections.
Since adhesion also plays a role, the material of the spout or the type of liquid (water, alcohol or oil, for example) is also relevant for the occurrence of the teapot effect.
The Coandă effect is sometimes mentioned in this context, but it is rarely cited in the scientific literature and is therefore not precisely defined. Often several different phenomena seem to be mixed up in this one. | 1 | Applied and Interdisciplinary Chemistry |
LHCGR have been found in many types of extragonadal tissues, and the physiologic role of some has remained largely unexplored. Thus receptors have been found in the uterus, sperm, seminal vesicles, prostate, skin, breast, adrenals, thyroid, neural retina, neuroendocrine cells, and (rat) brain. | 1 | Applied and Interdisciplinary Chemistry |
Carcinogenic cells undergo a metabolic rewiring during oncogenesis, and oncometabolites play an important role. In cancer, there are several reprogrammed metabolic pathways that help cells survive when nutrients are scarce: Aerobic glycolysis, an increase in glycolytic flux, also known as the Warburg effect, allows glycolytic intermediates to supply subsidiary pathways to meet the metabolic demands of proliferating tumorigenic cells. Another studied reprogrammed pathway is gain of function of the oncogene MYC. This gene encodes a transcription factor that boosts the expression of a number of genes involved in anabolic growth via mitochondrial metabolism. Oncometabolite production is another example of metabolic deregulation. | 1 | Applied and Interdisciplinary Chemistry |
All enzymes work within a range of temperature specific to the organism. Increases in temperature generally lead to increases in reaction rates. There is a limit to the increase because higher temperatures lead to a sharp decrease in reaction rates. This is due to the denaturating (alteration) of protein structure resulting from the breakdown of the weak ionic and hydrogen bonding that stabilize the three-dimensional structure of the enzyme active site. The "optimum" temperature for human enzymes is usually between 35 and 40 °C. The average temperature for humans is 37 °C. Human enzymes start to denature quickly at temperatures above 40 °C. Enzymes from thermophilic archaea found in the hot springs are stable up to 100 °C. However, the idea of an "optimum" rate of an enzyme reaction is misleading, as the rate observed at any temperature is the product of two rates, the reaction rate and the denaturation rate. If you were to use an assay measuring activity for one second, it would give high activity at high temperatures, however if you were to use an assay measuring product formation over an hour, it would give you low activity at these temperatures. | 1 | Applied and Interdisciplinary Chemistry |
In biochemistry, differences between the isotopomers of biochemicals such as starches is of practical importance in archaeology. They offer clues to the diet of prehistoric humans that lived as long ago as paleolithic times. This is because naturally occurring carbon dioxide contains both C and C. Monocots, such as rice and oats, differ from dicots, such as potatoes and tree fruits, in the relative amounts of CO and CO that they incorporate into their tissues as products of photosynthesis. When tissues of such subjects are recovered, usually tooth or bone, the relative isotopic content can give useful indications of the main source of the staple foods of the subjects of the investigations. | 0 | Theoretical and Fundamental Chemistry |
Chemcatcher® is a passive sampling device for monitoring a variety of pollutants (including trace metals, polycyclic aromatic hydrocarbons, pesticides and pharmaceutical residues) in water.
Chemcatcher® comprises a reusable three component, water-tight PTFE body. Two different designs are available to accommodate different types of commercially available 47 mm diameter receiving phase disks. | 0 | Theoretical and Fundamental Chemistry |
The soil vapor extraction remediation technology uses vacuum blowers and extraction wells to induce gas flow through the subsurface, collecting contaminated soil vapor, which is subsequently treated aboveground. SVE systems can rely on gas inflow through natural routes or specific wells may be installed for gas inflow (forced or natural). The vacuum extraction of soil gas induces gas flow across a site, increasing the mass transfer driving force from aqueous (soil moisture), non-aqueous (pure phase), and solid (soil) phase into the gas phase. Air flow across a site is thus a key aspect, but soil moisture and subsurface heterogeneity (i.e., a mixture of low and high permeability materials) can result in less gas flow across some zones. In some situations, such as enhancement of monitored natural attenuation, a passive SVE system that relies on barometric pumping may be employed.
SVE has several advantages as a vadose zone remediation technology. The system can be implemented with standard wells and off-the-shelf equipment (blowers, instrumentation, vapor treatment, etc.). SVE can also be implemented with a minimum of site disturbance, primarily involving well installation and minimal aboveground equipment. Depending on the nature of the contamination and the subsurface geology, SVE has the potential to treat large soil volumes at reasonable costs.
The soil gas (vapor) that is extracted by the SVE system generally requires treatment prior to discharge back into the environment. The aboveground treatment is primarily for a gas stream, although condensation of liquid must be managed (and in some cases may specifically be desired). A variety of treatment techniques are available for aboveground treatment and include thermal destruction (e.g., direct flame thermal oxidation, catalytic oxidizers), adsorption (e.g., granular activated carbon, zeolites, polymers), biofiltration, non-thermal plasma destruction, photolytic/photocatalytic destruction, membrane separation, gas absorption, and vapor condensation. The most commonly applied aboveground treatment technologies are thermal oxidation and granular activated carbon adsorption. The selection of a particular aboveground treatment technology depends on the contaminant, concentrations in the offgas, throughput, and economic considerations. | 1 | Applied and Interdisciplinary Chemistry |
The aliphatic biopolyesters are mainly polyhydroxyalkanoates (PHAs) like the poly-3-hydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxyhexanoate (PHH). | 0 | Theoretical and Fundamental Chemistry |
Source:
* Lomonosov Prize, 1974.
* Mendeleev Prize, 1979.
* Nesmeyanov Prize, 1991.
* Demidov Prize, 2003.
* State Prize, 2004.
* IUPAC 2013 Distinguished Women in Chemistry or Chemical Engineering Award, 2013. | 0 | Theoretical and Fundamental Chemistry |
Adam17 may facilitate entry of the SARS‑CoV‑2 virus, possibly by enabling fusion of virus particles with the cytoplasmic membrane. Adam17 has similar ACE2 cleavage activity as TMPRSS2, but by forming soluble ACE2, Adam17 may actually have the protective effect of blocking circulating SARS‑CoV‑2 virus particles.
Adam17 sheddase activity may contribute to COVID-19 inflammation by cleavage of TNF-α and Interleukin-6 receptor. | 1 | Applied and Interdisciplinary Chemistry |
Different isotopes of the same element can be considered as different kinds of atoms when enumerating isomers of a molecule or ion. The replacement of one or more atoms by their isotopes can create multiple structural isomers and/or stereoisomers from a single isomer.
For example, replacing two atoms of common hydrogen () by deuterium (, or ) on an ethane molecule yields two distinct structural isomers, depending on whether the substitutions are both on the same carbon (1,1-dideuteroethane, ) or one on each carbon (1,2-dideuteroethane, ); as if the substituent was chlorine instead of deuterium. The two molecules do not interconvert easily and have different properties, such as their microwave spectrum.
Another example would be substituting one atom of deuterium for one of the hydrogens in chlorofluoromethane (). While the original molecule is not chiral and has a single isomer, the substitution creates a pair of chiral enantiomers of , which could be distinguished (at least in theory) by their optical activity.
When two isomers would be identical if all isotopes of each element were replaced by a single isotope, they are described as isotopomers or isotopic isomers. In the above two examples if all were replaced by , the two dideuteroethanes would both become ethane and the two deuterochlorofluoromethanes would both become .
The concept of isotopomers is different from isotopologs or isotopic homologs, which differ in their isotopic composition. For example, and are isotopologues and not isotopomers, and are therefore not isomers of each other. | 0 | Theoretical and Fundamental Chemistry |
In molecular biology, the ankyrin-G binding motif of KCNQ2-3 is a protein motif found in the potassium channels KCNQ2 and KCNQ3.
Interactions with ankyrin-G (ankyrin-3) are crucial to the localisation of voltage-gated sodium channels (VGSCs) at the axonal initial segment and for neurons to initiate action potentials. This conserved 9-amino acid motif ((V/A)P(I/L)AXXE(S/D)D) is required for ankyrin-G binding and functions to localise sodium channels to a variety of excitable membrane domains both inside and outside of the nervous system. This motif has also been identified in the potassium channel 6TM proteins KCNQ2 and KCNQ3 that correspond to the M channels that exert a crucial influence over neuronal excitability. KCNQ2/KCNQ3 channels are preferentially localised to the surface of axons both at the axonal initial segment and more distally, and this axonal initial segment targeting of surface KCNQ channels is mediated by these ankyrin-G binding motifs of KCNQ2 and KCNQ3. KCNQ3 is a major determinant of M channel localisation to the AIS, rather than KCNQ2. Phylogenetic analysis reveals that anchor motifs evolved sequentially in chordates (NaV channel) and jawed vertebrates (KCNQ2/3). | 1 | Applied and Interdisciplinary Chemistry |
Research conducted by the American Cyanamid laboratories in the late 1940s and early 1950s demonstrated that adding penicillin to chicks' feed increased their weight gain by 10 per cent. The reasons for this were still subject to debate in the twenty-first century. Subsequent research indicated that adding penicillin to animal feed also improved feed conversion efficiency, promoted more uniform growth and facilitated disease control. After the Food and Drug Administration approved the use of penicillin as feed additives for poultry and livestock in 1951, the pharmaceutical companies ramped up production to meet the demand.
By 1954, the United States was producing of antibiotics each year, of which was going into animal feed; in the 1990s, the United States was producing of antibiotics per year, of which half was going to livestock. The largest user remained the poultry industry, which consumed of antibiotics each year, compared to for hogs and for cattle. A 1981 study by the Council for Agricultural Science and Technology estimated that banning their use in animal feed could cost American consumers up to $3.5 billion a year (equivalent to $ billion in ) in increased food prices. The story was similar in the UK, where 44 per cent of antibiotic production was consumed by animals by 1963.
By the mid-1950s, there were reports in the United States that milk was not curdling to make cheese. The FDA found that the milk was contaminated with penicillin, which was killing the bacteria required for cheesemaking. In 1963 the World Health Organization reported high levels of penicillin in milk worldwide. People who were allergic to penicillin could now get a reaction from drinking milk. A committee chaired by Lord Netherthorpe was established in the UK in 1960 to inquire into the use of antibiotics in animal feed. In 1962, the committee recommended that restrictions on the use of antibiotics in animals be relaxed. It contended that the benefits were substantial and that even if bacteria became resistant, new antibiotics would soon be developed, and there was no evidence that bacterial resistance in animals impacted human health.
The Netherthorpe committees conclusions were undermined by new research even before they were published, and the committee was recalled to reconsider the issue in 1965. New studies had shown that bacteria were not only were able to inherit the genes for antibiotic resistance, but they could also communicate them to each other. In 1967, a multiresistant strain of E. coli' killed fifteen children in the UK. The use of antibiotics in animals for nontherapeutic use was banned there in 1971. Many other European countries soon followed.
When Sweden acceded to the European Union (EU) in 1995, a total ban on antibiotic growth promoters (AGPs) had been in place there for ten years. This would be superseded by more relaxed EU rules unless Sweden could demonstrate scientific evidence in favour of a ban. Two Swedish scientists, Anders Franklin and Christina Greko, and two Danish scientists, and , took up the fight. The odds seemed against them but this coincided with the United Kingdom BSE outbreak, which resulted in intense political pressure. In December 1996, the European Parliament's Standing Committee on Health and Welfare voted to ban the use of AGPs. The EU went further and recommended broad restrictions on the use of antibiotics. | 1 | Applied and Interdisciplinary Chemistry |
"Deluge" systems are systems in which all sprinklers connected to the water piping system are open, in that the heat sensing operating element is removed. These systems are used for special hazards where rapid fire spread is a concern, as they provide a simultaneous application of water over the entire hazard.
Water is not present in the piping until the system operates. Because the sprinkler orifices are open, the piping is at atmospheric pressure. To prevent the water supply pressure from forcing water into the piping, a "deluge valve" (a mechanically latched valve) is used in the water supply connection. It is a non-resetting valve, and stays open once tripped.
Because the heat sensing elements normally present in automatic sprinklers have been removed (resulting in open sprinkler heads), the deluge valve is opened via a signal from the fire alarm system which utilizes fire detectors. The type of fire alarm initiating device is selected mainly based on the hazard (e.g. pilot sprinklers, smoke detectors, heat detectors, or optical flame detectors). The initiation device signals the fire alarm panel, which in turn signals the deluge valve to open. Activation can also be via an electric or pneumatic fire alarm pull station which signals the fire alarm panel to signal the deluge valve to open. | 1 | Applied and Interdisciplinary Chemistry |
Nucleotides are organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all life-forms on Earth. Nucleotides are obtained in the diet and are also synthesized from common nutrients by the liver.
Nucleotides are composed of three subunit molecules: a nucleobase, a five-carbon sugar (ribose or deoxyribose), and a phosphate group consisting of one to three phosphates. The four nucleobases in DNA are guanine, adenine, cytosine, and thymine; in RNA, uracil is used in place of thymine.
Nucleotides also play a central role in metabolism at a fundamental, cellular level. They provide chemical energy—in the form of the nucleoside triphosphates, adenosine triphosphate (ATP), guanosine triphosphate (GTP), cytidine triphosphate (CTP), and uridine triphosphate (UTP)—throughout the cell for the many cellular functions that demand energy, including: amino acid, protein and cell membrane synthesis, moving the cell and cell parts (both internally and intercellularly), cell division, etc.. In addition, nucleotides participate in cell signaling (cyclic guanosine monophosphate or cGMP and cyclic adenosine monophosphate or cAMP) and are incorporated into important cofactors of enzymatic reactions (e.g., coenzyme A, FAD, FMN, NAD, and NADP).
In experimental biochemistry, nucleotides can be radiolabeled using radionuclides to yield radionucleotides.
5-nucleotides are also used in flavour enhancers as food additive to enhance the umami taste, often in the form of a yeast extract. | 1 | Applied and Interdisciplinary Chemistry |
A novel application for gel electrophoresis is the separation or characterization of metal or metal oxide nanoparticles (e.g. Au, Ag, ZnO, SiO2) regarding the size, shape, or surface chemistry of the nanoparticles. The scope is to obtain a more homogeneous sample (e.g. narrower particle size distribution), which then can be used in further products/processes (e.g. self-assembly processes). For the separation of nanoparticles within a gel, the key parameter is the ratio of the particle size to the mesh size, whereby two migration mechanisms were identified: the unrestricted mechanism, where the particle size << mesh size, and the restricted mechanism, where particle size is similar to mesh size. | 1 | Applied and Interdisciplinary Chemistry |
Renal lipotoxicity occurs when excess long-chain nonesterified fatty acids are stored in the kidney and proximal tubule cells. It is believed that these fatty acids are delivered to the kidneys via serum albumin. This condition leads to tubulointerstitial inflammation and fibrosis in mild cases, and to kidney failure and death in severe cases. The current accepted treatments for lipotoxicity in renal cells are fibrate therapy and intensive insulin therapy. | 1 | Applied and Interdisciplinary Chemistry |
The first analysis, assuming a Faraday efficiency of 100%, yielded an average apparent excess heat of 21% of input power. The term "apparent excess heat" was coined by the investigators to indicate that the actual Faraday efficiency was ignored in the analysis. | 0 | Theoretical and Fundamental Chemistry |
Examples of industrial applications of these devices for intensifying processes are:
* preparation of food emulsions
* preparation of multicomponent suspensions with vulcanizing and gelling agents (sulfur, zinc oxide, soot, kaolin, sodium silicofluoride) in latex sponge production; Obtaining suspensions of titanium dioxide used as matting agent for chemical fibers
* wastewater treatment from acids, alkalis, hexavalent chromium compounds, nickel, iron, zinc, copper, cadmium, other heavy metals, cyanide compounds, and other contaminants
* production of greases and emulsions
* drilling fluid preparation
* preparation of kerosene in water emulsions, silicone, rubber, latex, etc.
Electromagnetic vortex intensifier grinds and regrinds coal, alumina-containing slag, quartz sand, technical diamonds, cellulose, chalk, wood flour, fluoroplastics, etc.
Also, it can be used for decontamination of agricultural animal waste. | 1 | Applied and Interdisciplinary Chemistry |
In 2002, a seminal paper on Brownian motors published in the American Institute of Physics magazine Physics Today, "Brownian motors", by Dean Astumian and Peter Hänggi. There, they proposed the then novel concept of Brownian motors and posited that "thermal motion combined with input energy gives rise to a channeling of chance that can be used to exercise control over microscopic systems". Astumian and Hänggi provide in their paper a copy of Wallace Stevens' 1919 poem, The Place of the Solitaries to elegantly illustrate, from an abstract perspective, the ceaseless nature of noise.
A year after the Astumian-Hänggi paper, David Leighs organic chemistry group reported the first artificial molecular Brownian motors. In 2007 the same team reported a Maxwells Demon-inspired molecular information ratchet.
Another important demonstration of nanoengineering and nanotechnology was the building of a practical artificial Brownian motor by IBM in 2018. Specifically, an energy landscape was created by accurately shaping a nanofluidic slit, and alternate potentials and an oscillating electric field were then used to “rock” nanoparticles to produce directed motion. The experiment successfully made the nanoparticles move along a track in the shape of the outline of the IBM logo, and serves as an important milestone in the practical use of Brownian motors and other elements at the nanoscale.Additionally, various institutions around the world, such as the University of Sydney Nano Institute, headquartered at the Sydney Nanoscience Hub (SNH), and the Swiss Nanoscience Institute (SNI) at the University of Basel, are examples of the research activity emerging in the field of nanoscience. Brownian motors remain a central concept in both the understanding of natural molecular motors and the construction of useful nanoscale machines that involve directed motion. | 0 | Theoretical and Fundamental Chemistry |
In 1984, Martin Peng proposed an alternate arrangement of magnet coils that would greatly reduce the aspect ratio while avoiding the erosion issues of the compact tokamak: a spherical tokamak. Instead of wiring each magnet coil separately, he proposed using a single large conductor in the center, and wiring the magnets as half-rings off of this conductor. What was once a series of individual rings passing through the hole in the center of the reactor was reduced to a single post, allowing for aspect ratios as low as 1.2. The ST concept appeared to represent an enormous advance in tokamak design. The proposal came during a period when US fusion research budgets were dramatically smaller. ORNL was provided with funds to develop a suitable central column built out of a high-strength copper alloy called "Glidcop". However, they were unable to secure funding to build a demonstration machine.
Failing at ORNL, Peng began a worldwide effort to interest other teams in the concept and get a test machine built. One approach would be to convert a spheromak. Peng's advocacy caught the interest of Derek Robinson, of the United Kingdom Atomic Energy Authority. Robinson gathered a team and secured on the order of 100,000 pounds to build an experimental machine, the Small Tight Aspect Ratio Tokamak, or START. Parts of the machine were recycled from earlier projects, while others were loaned from other labs, including a 40 keV neutral beam injector from ORNL. Construction began in 1990 and operation started in January 1991. It achieved a record beta (plasma pressure compared to magnetic field pressure) of 40% using a neutral beam injector | 0 | Theoretical and Fundamental Chemistry |
Micellar liquid chromatography (MLC) is a form of reversed phase liquid chromatography that uses an aqueous micellar solutions as the mobile phase. | 0 | Theoretical and Fundamental Chemistry |
The replication cycle of a retrovirus entails the insertion ("integration") of a DNA copy of the viral genome into the nuclear genome of the host cell. Most retroviruses infect somatic cells, but occasional infection of germline cells (cells that produce eggs and sperm) can also occur. Rarely, retroviral integration may occur in a germline cell that goes on to develop into a viable organism. This organism will carry the inserted retroviral genome as an integral part of its own genome—an "endogenous" retrovirus (ERV) that may be inherited by its offspring as a novel allele. Many ERVs have persisted in the genome of their hosts for millions of years. However, most of these have acquired inactivating mutations during host DNA replication and are no longer capable of producing the virus. ERVs can also be partially excised from the genome by a process known as recombinational deletion, in which recombination between the identical sequences that flank newly integrated retroviruses results in deletion of the internal, protein-coding regions of the viral genome.
The general retrovirus genome consists of three genes vital for the invasion, replication, escape, and spreading of its viral genome. These three genes are gag (encodes for structural proteins for the viral core), pol (encodes for reverse transcriptase, integrase, and protease), and env (encodes for coat proteins for the viruss exterior). These viral proteins are encoded as polyproteins. In order to carry out their life cycle, the retrovirus relies heavily on the host cells machinery. Protease degrades peptide bonds of the viral polyproteins, making the separate proteins functional. Reverse transcriptase functions to synthesize viral DNA from the viral RNA in the host cell's cytoplasm before it enters the nucleus. Integrase guides the integration of viral DNA into the host genome.
Over time, the genome of ERVs not only acquire point mutations, but also shuffle and recombine with other ERVs. ERVs with a decayed sequence for the env become more likely to propagate. | 1 | Applied and Interdisciplinary Chemistry |
Mutation in genes (XPB), (XPD) or (TTDA) cause trichothiodystrophy, a condition characterized by photosensitivity, ichthyosis, brittle hair and nails, intellectual impairment, decreased fertility and/or short stature. | 1 | Applied and Interdisciplinary Chemistry |
These occur between alkenes and electrophiles, often halogens as in halogen addition reactions. Common reactions include use of bromine water to titrate against a sample to deduce the number of double bonds present. For example, ethene + bromine → 1,2-dibromoethane:
:CH + Br → BrCHCHBr
This takes the form of 3 main steps shown below;
#Forming of a π-complex
#:The electrophilic Br-Br molecule interacts with electron-rich alkene molecule to form a π-complex 1.
#Forming of a three-membered bromonium ion
#:The alkene is working as an electron donor and bromine as an electrophile. The three-membered bromonium ion 2 consisted of two carbon atoms and a bromine atom forms with a release of Br.
#Attacking of bromide ion
#:The bromonium ion is opened by the attack of Br from the back side. This yields the vicinal dibromide with an antiperiplanar configuration. When other nucleophiles such as water or alcohol are existing, these may attack 2 to give an alcohol or an ether.
This process is called Ad2 mechanism ("addition, electrophilic, second-order"). Iodine (I), chlorine (Cl), sulfenyl ion (RS), mercury cation (Hg), and dichlorocarbene (:CCl) also react through similar pathways. The direct conversion of 1 to 3 will appear when the Br is large excess in the reaction medium. A β-bromo carbenium ion intermediate may be predominant instead of 3 if the alkene has a cation-stabilizing substituent like phenyl group. There is an example of the isolation of the bromonium ion 2. | 0 | Theoretical and Fundamental Chemistry |
In host-guest chemistry, cucurbiturils are macrocyclic molecules made of glycoluril () monomers linked by methylene bridges (). The oxygen atoms are located along the edges of the band and are tilted inwards, forming a partly enclosed cavity (cavitand). The name is derived from the resemblance of this molecule with a pumpkin of the family of Cucurbitaceae.
Cucurbiturils are commonly written as cucurbit[n]uril, where n is the number of glycoluril units. Two common abbreviations are CB[n], or simply CBn.
These compounds are particularly interesting to chemists because they are suitable hosts for an array of neutral and cationic species. The binding mode is thought to occur through hydrophobic interactions, and, in the case of cationic guests, through cation-dipole interactions as well. The dimensions of cucurbiturils are generally on the ~10 Å size scale. For instance, the cavity of cucurbit[6]uril has a height ~9.1 Å, an outer diameter ~5.8 Å, and an inner diameter ~3.9 Å.
Cucurbiturils were first synthesized in 1905 by Robert Behrend, by condensing glycoluril with formaldehyde, but their structure was not elucidated until 1981. The field expanded as CB5, CB7, and CB8 were discovered and isolated by Kim Kimoon in the year 2000. To date cucurbiturils composed of 5, 6, 7, 8, 10, and 14 repeat units have all been isolated, which have internal cavity volumes of 82, 164, 279, 479, and 870 Å respectively. A cucurbituril composed of 9 repeat units has yet to be isolated (as of 2009). Other common molecular capsules that share a similar molecular shape with cucurbiturils include cyclodextrins, calixarenes, and pillararenes. | 0 | Theoretical and Fundamental Chemistry |
Transnasal evaporative cooling is a method of inducing the hypothermia process and provides a means of continuous cooling of a person throughout the early stages of targeted temperature management and during movement throughout the hospital environment. This technique uses two cannulae, inserted into a person's nasal cavity, to deliver a spray of coolant mist that evaporates directly underneath the brain and base of the skull. As blood passes through the cooling area, it reduces the temperature throughout the rest of the body.
The method is compact enough to be used at the point of cardiac arrest, during ambulance transport, or within the hospital proper. It is intended to reduce rapidly the person's temperature to below while targeting the brain as the first area of cooling. Research into the device has shown cooling rates of per hour in the brain (measured through infrared tympanic measurement) and per hour for core body temperature reduction. | 1 | Applied and Interdisciplinary Chemistry |
The O−O bond length in peroxides is about 1.45 Å, and the R−O−O angles (R = H, C) are about 110° (water-like). Characteristically, the C−O−O−R (R = H, C) dihedral angles are about 120°. The O−O bond is relatively weak, with a bond dissociation energy of , less than half the strengths of C−C, C−H, and C−O bonds. | 0 | Theoretical and Fundamental Chemistry |
Sinapaldehyde is an organic compound with the formula HO(CHO)CHCH=CHCHO. It is a derivative of cinnamaldehyde, featuring one hydroxy group and two methoxy groups as substituents. It is an intermediate in the formation of sinapyl alcohol, a lignol that is a major precursor to lignin. | 1 | Applied and Interdisciplinary Chemistry |
The Geochemical Ocean Sections Study (GEOSECS) was a global survey of the three-dimensional distributions of chemical, isotopic, and radiochemical tracers in the ocean. A key objective was to investigate the deep thermohaline circulation of the ocean, using chemical tracers, including radiotracers, to establish the pathways taken by this.
Expeditions undertaken during GEOSECS took place in the Atlantic Ocean from July 1972 to May 1973, in the Pacific Ocean from August 1973 to June 1974, and in the Indian Ocean from December 1977 to March 1978.
Measurements included those of physical oceanographic quantities such as temperature, salinity, pressure and density, chemical / biological quantities such as total inorganic carbon, alkalinity, nitrate, phosphate, silicic acid, oxygen and apparent oxygen utilisation (AOU), and radiochemical / isotopic quantities such as carbon-13, carbon-14 and tritium. | 0 | Theoretical and Fundamental Chemistry |
Li Zhou and coworkers used a volumetric apparatus to measure the adsorption equilibria of hydrogen and methane on activated carbon (Figure 2, 3). They also measure the adsorption equilibria of nitrogen on microporous activated carbon (Figure 4) and on a mesoporous silica gel (Figure 5) for both subcritical and supercritical region. Figure 6 shows the isotherms of methane on silica gel. | 0 | Theoretical and Fundamental Chemistry |
LD for the HCl salt of pempidine in mice: 74 mg/kg (intravenous); 125 mg/kg (intraperitoneal); 413 mg/kg (oral). | 0 | Theoretical and Fundamental Chemistry |
The eluant from the column passes through one or more flow cells to measure the concentration of protein in the eluant (by UV light absorption at 280 nm). The conductivity cell measures the buffer conductivity, usually in millisiemens/cm, which indicates the concentration of salt in the buffer. A flow cell which measures pH of the buffer is also commonly included. Usually each flow cell is connected to a separate electronics module which provides power and amplifies the signal. | 0 | Theoretical and Fundamental Chemistry |
Sodium hydroxide has been used for detection of carbon monoxide poisoning, with blood samples of such patients turning to a vermilion color upon the addition of a few drops of sodium hydroxide. Today, carbon monoxide poisoning can be detected by CO oximetry. | 0 | Theoretical and Fundamental Chemistry |
The porous medium equation, also called the nonlinear heat equation, is a nonlinear partial differential equation taking the form:where is the Laplace operator. It may also be put into its equivalent divergence form:where may be interpreted as a diffusion coefficient and is the divergence operator. | 1 | Applied and Interdisciplinary Chemistry |
According to the bibliographer Ibn al-Nadīm, the first Muslim alchemist was Khālid ibn Yazīd, who is said to have studied alchemy under the Christian Marianos of Alexandria. The historicity of this story is not clear; according to M. Ullmann, it is a legend. According to Ibn al-Nadīm and Ḥajjī Khalīfa, he is the author of the alchemical works Kitāb al-kharazāt (The Book of Pearls), Kitāb al-ṣaḥīfa al-kabīr (The Big Book of the Roll), Kitāb al-ṣaḥīfa al-saghīr (The Small Book of the Roll), Kitāb Waṣīyatihi ilā bnihi fī-ṣ-ṣanʿa (The Book of his Testament to his Son about the Craft), and Firdaws al-ḥikma (The Paradise of Wisdom), but again, these works may be pseudepigraphical. | 1 | Applied and Interdisciplinary Chemistry |
The lack of drugs and unavailability of experimental treatment in the most affected regions of the West African Ebola virus outbreak spurred some controversy. The fact that the drug was first given to Americans and a European and not to Africans, according to the Los Angeles Times, "provoked outrage, feeding into African perceptions of Western insensitivity and arrogance, with a deep sense of mistrust and betrayal still lingering over the exploitation and abuses of the colonial era". Salim S. Abdool Karim, the director of an AIDS research center in South Africa, placed the issue in the context of the history of exploitation and abuses. Responding to a question on how people might have reacted if ZMapp and other drugs had first been used on Africans, he said "It would have been the front-page screaming headline: Africans used as guinea pigs for American drug companys medicine.
In early August, the World Health Organization called for convening a panel of medical authorities "to consider whether experimental drugs should be more widely released." In a statement, Peter Piot (co-discoverer of the Ebola virus); Jeremy Farrar, the director of the Wellcome Trust; and David Heymann of the Chatham House Center on Global Health Security, called for the release of experimental drugs for affected African nations.
At an August 6, 2014 press conference, Barack Obama, the President of the United States, was questioned regarding whether the cocktail should be fast-tracked for approval or be made available to sick patients outside of the United States. He responded, "I think weve got to let the science guide us. I dont think all the information's in on whether this drug is helpful." | 1 | Applied and Interdisciplinary Chemistry |
Nanofluids are produced by several techniques:
# Direct Evaporation (1 step)
# Gas condensation/dispersion (2 step)
# Chemical vapour condensation (1 step)
# Chemical precipitation (1 step)
# Bio-based (2 step)
Several liquids including water, ethylene glycol, and oils have been used as base fluids. Although stabilization can be a challenge, on-going research indicates that it is possible. Nano-materials used so far in nanofluid synthesis include metallic particles, oxide particles, carbon nanotubes, graphene nano-flakes and ceramic particles.
A bio-based, environmentally friendly approach for the covalent functionalization of multi-walled carbon nanotubes (MWCNTs) using clove buds was developed. There are no any toxic and hazardous acids which are typically used in common carbon nanomaterial functionalization procedures, employed in this synthesis. The MWCNTs are functionalized in one pot using a free radical grafting reaction. The clove-functionalized MWCNTs are then dispersed in distilled water (DI water), producing a highly stable MWCNT aqueous suspension (MWCNTs Nanofluid). | 0 | Theoretical and Fundamental Chemistry |
In his work "On Floating Bodies", Archimedes famously stated:
While this basic idea carried enormous weight and has come to form the basis of understanding why objects float, it is best applied for objects with a characteristic length scale greater than the capillary length. What Archimedes had failed to predict was the influence of surface tension and its impact at small length scales.
More recent works, such as that of Keller, have extended these principles by considering the role of surface tension forces on partially submerged bodies. Keller, for instance, demonstrated analytically that the weight of water displaced by a meniscus is equal to the vertical component of the surface tension force.
Nonetheless, the role of flexibility and its impact on an object's load-bearing potential is one that did receive attention until the mid-2000s and onward. In an initial study, Vella studied the load supported by a raft composed of thin, rigid strips. Specifically, he compared the case of floating individual strips to floating an aggregation of strips, wherein the aggregate structure causes portions of the meniscus (and hence, resulting surface tension force) to disappear. By extending his analysis to consider a similar system composed of thin strips of some finite bending stiffness, he found that this later case in fact was able support a greater load.
A well known work in the area of surface tension aided flotation was the analysis of water strider locomotion along the surface of water. Using the idea of flexible structures, Ji et al. re-examined this problem by considering the compliance of a water strider leg. By modeling the leg as a compliant structure that deforms at the water surface (rather than pierce it), Ji was able to ascertain what added benefit this flexibility has in supporting the insect. Other studies on the water strider have examined the ways in which flexibility can affect wetting properties of the leg.
Another track of research has been to investigate how exactly the interaction between liquid and a compliant object leads to the resulting deformation. In one example, such analysis has been extended to explain the difficulty in submerging hairs in a fluid. These works focus on behavior near the contact line, and consider what role non-linear effects such as slippage play. | 1 | Applied and Interdisciplinary Chemistry |
The extraction cell is filled with the solid sample to be examined and placed in a temperature-controllable oven. After adding the solvent, the cell is heated at constant pressure (adjustable between 0.3 and 20 MPa) up to a maximum temperature of 200°C and kept at constant conditions for a while so that equilibrium can be established. The extract is then transferred to a sample tube. A sample often goes through several extraction cycles. Finally, the extraction cell is rinsed with solvent, the rinsing valve is opened and the cell and all lines are rinsed with nitrogen and the apparatus is prepared for further extractions. | 0 | Theoretical and Fundamental Chemistry |
Rhodoquinone (RQ) is a modified ubiquinone-like molecule that is an important cofactor used in anaerobic energy metabolism by many organisms. Recently, it has gained attention as a potential anthelmintic drug target due to the fact that parasitic hosts do not synthesize or use this cofactor. Because this cofactor is used in low oxygen environments, many helminth-like organisms have adapted to survive host environments such as the areas within the gastrointestinal tracks. | 1 | Applied and Interdisciplinary Chemistry |
Thermoelectric cooling uses the Peltier effect to create a heat flux between the junction of two types of material. This effect is commonly used in camping and portable coolers and for cooling electronic components and small instruments. Peltier coolers are often used where a traditional vapor-compression cycle refrigerator would be impractical or take up too much space, and in cooled image sensors as an easy, compact and lightweight, if inefficient, way to achieve very low temperatures, using two or more stage peltier coolers arranged in a cascade refrigeration configuration, meaning that two or more Peltier elements are stacked on top of each other, with each stage being larger than the one before it, in order to extract more heat and waste heat generated by the previous stages. Peltier cooling has a low COP (efficiency) when compared with that of the vapor-compression cycle, so it emits more waste heat (heat generated by the Peltier element or cooling mechanism) and consumes more power for a given cooling capacity. | 0 | Theoretical and Fundamental Chemistry |
** After considering the concept for some time, John Nuckolls publishes the concept of inertial confinement fusion. The laser, introduced the same year, appears to be a suitable "driver".
** The Soviet Union test the Tsar Bomba (50 megatons), the most powerful thermonuclear weapon ever.
** Plasma temperatures of approximately 40 million degrees Celsius and a few billion deuteron-deuteron fusion reactions per discharge were achieved at LANL with the Scylla IV device.
** At an international meeting at the UKs new fusion research centre in Culham, the Soviets release early results showing greatly improved performance in toroidal pinch machines. The announcement is met by scepticism, especially by the UK team whos ZETA was largely identical. Spitzer, chairing the meeting, essentially dismisses it out of hand.
** At the same meeting, odd results from the ZETA machine are published. It will be years before the significance of these results are realized.
** By the end of the meeting, it is clear that most fusion efforts have stalled. All of the major designs, including the stellarator, pinch machines and magnetic mirrors are all losing plasma at rates that are simply too high to be useful in a reactor setting. Less-known designs like the levitron and astron are faring no better.
** The 12-beam "4 pi laser" using ruby as the lasing medium is developed at Lawrence Livermore National Laboratory (LLNL) includes a gas-filled target chamber of about 20 centimeters in diameter.
** Demonstration of Farnsworth-Hirsch Fusor appeared to generate neutrons in a nuclear reaction.
** Hans Bethe wins the 1967 Nobel Prize in physics for his publication on how fusion powers the stars in work of 1939.
** Robert L. Hirsch is hired by Amasa Bishop of the Atomic Energy Commission as staff physicist. Hirsch would eventually end up running the fusion program during the 1970s.
** Further results from the T-3 tokamak, similar to the toroidal pinch machine mentioned in 1965, claims temperatures to be over an order of magnitude higher than any other device. The Western scientists remain highly sceptical.
** The Soviets invite a UK team from ZETA to perform independent measurements on T-3.
** The UK team, nicknamed "The Culham Five", confirm the Soviet results early in the year. They publish their results in Octobers edition of Nature'. This leads to a "veritable stampede" of tokamak construction around the world.
** After learning of the Culham Five's results in August, a furious debate breaks out in the US establishment over whether or not to build a tokamak. After initially pooh-poohing the concept, the Princeton group eventually decides to convert their stellarator to a tokamak. | 0 | Theoretical and Fundamental Chemistry |
Generally associated with exposure to beryllium levels at or above 100 μg/m, it produces severe cough, sore nose and throat, weight loss, labored breathing, anorexia, and increased fatigue.
In addition to beryllium's toxicity when inhaled, when brought into contact with skin at relatively low doses, beryllium can cause local irritation and contact dermatitis, and contact with skin that has been scraped or cut may cause rashes or ulcers. Beryllium dust or powder can irritate the eyes. | 1 | Applied and Interdisciplinary Chemistry |
Some typical Doppler-broadened NICE-OHMS signals, from 13 ppb (10 μTorr, 13•10 atm) of CH detected in a cavity with a finesse of 4800, are shown in the figure. (a) fm- and (b) wm-signal. Individual markers: measured data; Solid curves: theoretical fits. | 0 | Theoretical and Fundamental Chemistry |
Ammonia-Oxidizing Bacteria (AOB) are typically Gram-negative bacteria and belong to Betaproteobacteria and Gammaproteobacteria including the commonly studied genera including Nitrosomonas and Nitrococcus. They are known for their ability to utilize ammonia as an energy source and are prevalent in a wide range of environments, such as soils, aquatic systems, and wastewater treatment plants.
AOB possess enzymes called ammonia monooxygenases (AMOs), which are responsible for catalyzing the conversion of ammonia to hydroxylamine (NHOH), a crucial intermediate in the process of nitrification. This enzymatic activity is sensitive to environmental factors, such as pH, temperature, and oxygen availability.
AOB play a vital role in soil nitrification, making them key players in nutrient cycling. They contribute to the transformation of ammonia derived from organic matter decomposition or fertilizers into nitrite, which subsequently serves as a substrate for nitrite-oxidizing bacteria (NOB). | 1 | Applied and Interdisciplinary Chemistry |
The appearance of oxhide ingots in the archaeological record corresponds with the beginning of the bulk copper trade in the Mediterranean—approximately 1600 BC. The earliest oxhide ingots found come from Crete and date to the Late Minoan IB, approximately 1500 BC to 1450 BC. The latest oxhide ingots date to approximately 1000 BC, and were found on Sardinia. The copper trade was largely maritime: the principal sites where oxhide ingots are found are at sea, on the coast, and on islands. | 1 | Applied and Interdisciplinary Chemistry |
Because hypophosphorous acid can reduce elemental iodine to form hydroiodic acid, which is a reagent effective for reducing ephedrine or pseudoephedrine to methamphetamine, the United States Drug Enforcement Administration designated hypophosphorous acid (and its salts) as a List I precursor chemical effective November 16, 2001. Accordingly, handlers of hypophosphorous acid or its salts in the United States are subject to stringent regulatory controls including registration, recordkeeping, reporting, and import/export requirements pursuant to the Controlled Substances Act and 21 CFR §§ 1309 and 1310. | 0 | Theoretical and Fundamental Chemistry |
If the two side-chains on the central carbon are different from each other—either an aldoxime, or a ketoxime with two different "R" groups—the oxime can often have two different geometric stereoisomeric forms according to the E/Z configuration. An older terminology of syn and anti was used to identify especially aldoximes according to whether the R group was closer or further from the hydroxyl. Both forms are often stable enough to be separated from each other by standard techniques.
Oximes have three characteristic bands in the infrared spectrum, whose wavelengths corresponding to the stretching vibrations of its three types of bonds: 3600 cm (O−H), 1665 cm (C=N) and 945 cm (N−O).
In aqueous solution, aliphatic oximes are 10- to 10-fold more resistant to hydrolysis than analogous hydrazones. | 0 | Theoretical and Fundamental Chemistry |
Anti-wear (AW) hydraulic oils are made from a petroleum base fluid and commonly contain the anti-wear additive Zinc dialkyldithiophosphate (ZDDP). This additive works to protect the hydraulic pump. They come in multiple viscosity grades that have varying applications. For example, AW 46 hydraulic oils can be used to operate the hydraulic systems in off-road equipment such as dump trucks, excavators, and backhoes, while AW 32 hydraulic oils may be more suitable for colder weather applications like in a snow plow's pump. | 1 | Applied and Interdisciplinary Chemistry |
Microspectrophotometry is the measure of the spectra of microscopic samples using different wavelengths of electromagnetic radiation (e.g. ultraviolet, visible and near infrared, etc.) It is accomplished with microspectrophotometers, cytospectrophotometers, microfluorometers, Raman microspectrophotometers, etc. A microspectrophotometer can be configured to measure transmittance, absorbance, reflectance, light polarization, fluorescence (or other types of luminescence such as photoluminescence) of sample areas less than a micrometer in diameter through a modified optical microscope. | 0 | Theoretical and Fundamental Chemistry |
Native iron in the metallic state occurs rarely as small inclusions in certain basalt rocks. Besides meteoritic iron, Thule people of Greenland have used native iron from the Disko region. | 1 | Applied and Interdisciplinary Chemistry |
Kamal was born on 5 April 1959 in the Nile Delta city Zagazig. He attended Cairo University, faculty of engineering, and graduated from the chemical engineering department in 1982. Kamal began his career at the state-owned Engineering for Petroleum and Process Industries (Enppi) as an engineer. A few years later, Kamal switched to another public-sector energy company, known as Petrojet. | 1 | Applied and Interdisciplinary Chemistry |
The focus of Hieberts research was the history and philosophy of chemistry and physical sciences in the 2nd half of 19th century and 1st half of the 20th century. During his lifetime he completed three books and his fourth book (which deals with acoustics) was nearly complete at the time of his death. His book 1961 book The Impact of Atomic Energy examined the Manhattan Project, the atomic bombs dropped on Hiroshima and Nagasaki, and WW IIs consequences related to atomic energy from an ethical and religious perspective. He wrote numerous papers on the history of science, the relations between science and religion, and the philosophy of science as viewed by outstanding scientists of the modern era, especially among those scientists from 1850 to 1930 in Germany and Austria. His 1962 book Historical Roots of the Principle of Conservation of Energy is a notable achievement in writing the history of thermodynamics. He wrote papers about the science and philosophy of Max Planck, Ernst Mach, Walther Nernst, Ludwig Boltzmann, Hermann von Helmholtz, and Wilhelm Ostwald. Hiebert
had a strong conviction that historians of science should have a good, scientific grounding in the particular science that they study and write about. | 0 | Theoretical and Fundamental Chemistry |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), and Valine (Val, V). | 1 | Applied and Interdisciplinary Chemistry |
In addition, it is thought that extensive salinity stratification can lead to a reduction in the meridional overturning circulation (MOC) through the slowing of thermohaline circulation. Increased stratification means that there is effectively a barrier to subduction of parcels of water; isopycnals effectively do not outcrop at the surface and are parallel to the surface. The ocean, in this case, can be described as "less ventilated", and this has been implicated in the slowing down of the MOC. | 0 | Theoretical and Fundamental Chemistry |
The local Nusselt number for laminar flow over a flat plate, at a distance downstream from the edge of the plate, is given by
The average Nusselt number for laminar flow over a flat plate, from the edge of the plate to a downstream distance , is given by | 1 | Applied and Interdisciplinary Chemistry |
In physics, the gyromagnetic ratio (also sometimes known as the magnetogyric ratio in other disciplines) of a particle or system is the ratio of its magnetic moment to its angular momentum, and it is often denoted by the symbol Gamma|, gamma. Its SI unit is the radian per second per tesla (rad⋅s⋅T) or, equivalently, the coulomb per kilogram (C⋅kg).
The term "gyromagnetic ratio" is often used as a synonym for a different but closely related quantity, the -factor. The -factor only differs from the gyromagnetic ratio in being dimensionless. | 0 | Theoretical and Fundamental Chemistry |
RMR is regularly used in ecology to study the response of individuals to changes in environmental conditions.
Parasites by definition have a negative impact on their hosts and it is thus expected that there might be effects on host RMR. Varying effects of parasite infection on host RMR have been found. Most studies indicate an increase in RMR with parasite infection, but others show no effect, or even a decrease in RMR. It is still unclear why such variation in the direction of change in RMR with parasite infection is seen. | 1 | Applied and Interdisciplinary Chemistry |
Crookes became interested in spiritualism in the late 1860s, and was most strongly involved around 1874–1875. Eric Deeson notes that Crookes's studies of the occult are related to his scientific work on radiometry in that both involved the detection of previously undiscovered forces.
Crookes was possibly influenced by the death of his younger brother Philip in 1867 at 21 from yellow fever contracted while he was on an expedition to lay a telegraph cable from Cuba to Florida.
In 1867, influenced by Cromwell Fleetwood Varley, Crookes attended a séance to try to get in touch with his brother.
Between 1871 and 1874, Crookes studied the mediums Kate Fox, Florence Cook, and Daniel Dunglas Home. After his investigation, he believed that the mediums could produce genuine paranormal phenomena and communicate with spirits. Psychologists Leonard Zusne and Warren H. Jones have described Crookes as gullible as he endorsed fraudulent mediums as genuine.
The anthropologist Edward Clodd noted that Crookes had poor eyesight, which may have explained his belief in spiritualist phenomena and quoted William Ramsay as saying that Crookes is "so shortsighted that, despite his unquestioned honesty, he cannot be trusted in what he tells you he has seen." Biographer William Hodson Brock wrote that Crookes was "evidently short-sighted, but did not wear spectacles until the 1890s. Until then he may have used a monocle or pocket magnifying glass when necessary. What limitations this imposed upon his psychic investigations we can only imagine."
After studying the reports of Florence Cook, the science historian Sherrie Lynne Lyons wrote that the alleged spirit "Katie King" was at times Cook herself and at other times an accomplice. Regarding Crookes, Lyons wrote, "Here was a man with a flawless scientific reputation, who discovered a new element, but could not detect a real live maiden who was masquerading as a ghost". Cook was repeatedly exposed as a fraudulent medium but she had been "trained in the arts of the séance" which managed to trick Crookes. Some researchers such as Trevor H. Hall suspected that Crookes had an affair with Cook.
In a series of experiments in London, England at the house of Crookes in February 1875, the medium Anna Eva Fay managed to fool Crookes into believing she had genuine psychic powers. Fay later confessed to her fraud and revealed the tricks that she had used. Regarding Crookes and his experiments with mediums, the magician Harry Houdini suggested that Crookes had been deceived. The physicist Victor Stenger wrote that the experiments were poorly controlled and "his desire to believe blinded him to the chicanery of his psychic subjects."
In 1897, John Grier Hibben wrote that Crookes's idea of ether waves explaining telepathy was not a scientific hypothesis "he presents no facts to indicate its probability or to save it from being relegated to the sphere of bare conjecture."
In 1916, William Hope tricked Crookes with a fake spirit photograph of his wife. Oliver Lodge revealed there had been obvious signs of double exposure, the picture of Lady Crookes had been copied from a wedding anniversary photograph, but Crookes was a convinced spiritualist and claimed it was genuine evidence for spirit photography.
The physiologist Gordon Stein suspected that Crookes was too ashamed to admit he had been duped by the medium Florence Cook or that he conspired with her for sexual favors. He also suggested that Crookes had conspired with Anna Eva Fay. He noted that contrary to popular belief, Hope had been exposed as a fraud on several occasions. Stein concluded that all feats of Hope were conjuring tricks. In a review, biographer William Brock wrote that Stein made his "case against Crookes and Home clearly and logically."
Crookes joined the Society for Psychical Research, becoming its president in the 1890s: he also joined the Theosophical Society and The Ghost Club, of which he was president from 1907 to 1912. In 1890 he was initiated into the Hermetic Order of the Golden Dawn. | 1 | Applied and Interdisciplinary Chemistry |
The action potential generated at the axon hillock propagates as a wave along the axon. The currents flowing inwards at a point on the axon during an action potential spread out along the axon, and depolarize the adjacent sections of its membrane. If sufficiently strong, this depolarization provokes a similar action potential at the neighboring membrane patches. This basic mechanism was demonstrated by Alan Lloyd Hodgkin in 1937. After crushing or cooling nerve segments and thus blocking the action potentials, he showed that an action potential arriving on one side of the block could provoke another action potential on the other, provided that the blocked segment was sufficiently short.
Once an action potential has occurred at a patch of membrane, the membrane patch needs time to recover before it can fire again. At the molecular level, this absolute refractory period corresponds to the time required for the voltage-activated sodium channels to recover from inactivation, i.e., to return to their closed state. There are many types of voltage-activated potassium channels in neurons. Some of them inactivate fast (A-type currents) and some of them inactivate slowly or not inactivate at all; this variability guarantees that there will be always an available source of current for repolarization, even if some of the potassium channels are inactivated because of preceding depolarization. On the other hand, all neuronal voltage-activated sodium channels inactivate within several milliseconds during strong depolarization, thus making following depolarization impossible until a substantial fraction of sodium channels have returned to their closed state. Although it limits the frequency of firing, the absolute refractory period ensures that the action potential moves in only one direction along an axon. The currents flowing in due to an action potential spread out in both directions along the axon. However, only the unfired part of the axon can respond with an action potential; the part that has just fired is unresponsive until the action potential is safely out of range and cannot restimulate that part. In the usual orthodromic conduction, the action potential propagates from the axon hillock towards the synaptic knobs (the axonal termini); propagation in the opposite direction—known as antidromic conduction—is very rare. However, if a laboratory axon is stimulated in its middle, both halves of the axon are "fresh", i.e., unfired; then two action potentials will be generated, one traveling towards the axon hillock and the other traveling towards the synaptic knobs. | 0 | Theoretical and Fundamental Chemistry |
*Uranium
*Enriched uranium
*Nuclear weapon design
*The technology of mining and metallurgy [http://www.unu.edu/unupress/unupbooks/uu29me/uu29me08.htm], retrieved 7 October 2005. | 1 | Applied and Interdisciplinary Chemistry |
Also shown on the map is a typical steady state working (or operating/running) line. This is a locus of the operating points of the engine, as it is throttled.
Being a high pressure ratio device, the working line is relatively shallow. If the unit had no variable geometry, there would be handling problems, because the surge line would be very steep and cross the working line at part-flow.
During a slam-acceleration from a mid-throttle setting, the compressor working line will move rapidly towards surge and then slowly approach the steady state operating point, further up the map. The reverse effect occurs during a slam-deceleration. These effects are caused by the sluggish response of the spool (i.e. inertia effects) to rapid changes in engine fuel flow. Compressor surge is a particular problem during slam-accelerations and can be overcome by suitable adjustments to the fueling schedule and/or use of blow-off (bleeding air off the compressor, for handling purposes).
In the particular example shown, a slam-acceleration from ground idle would cause a high-pressure compressor surge. Opening the blow-off would help, but some changes to the variable stator schedule might also be required.
Because a high-pressure compressor sees the choked flow capacity of the high-pressure turbine, the compressor working line is hardly affected by flight conditions. The slope of the working line approximates to a constant corrected outlet flow. | 0 | Theoretical and Fundamental Chemistry |
The human genome contains about 28 million CpG sites, and roughly 60% of the CpG sites are methylated at the 5 position of the cytosine. During formation of a cancer there is an average reduction of the number of methylated cytosines of about 5% to 20%, or about 840,00 to 3.4 million demethylations of CpG sites.
DNMT1 methylates CpGs on hemi-methylated DNA during DNA replication. Thus, when a DNA strand has a methylated CpG, and the newly replicated strand during semi-conservative replication lacks a methyl group on the complementary CpG, DNMT1 is normally recruited to the hemimethylated site and adds a methyl group to cytosine in the newly synthesized CpG. However, recruitment of DNMT1 to hemimethylated CpG sites during DNA replication depends on the UHRF1 protein. If UHRF1 does not bind to a hemimethylated CpG site, then DNMT1 is not recruited and cannot methylate the newly synthesized CpG site. The arginine methyltransferase PRMT6 regulates DNA methylation by methylating the arginine at position 2 of histone 3 (H3R2me2a). (See Protein methylation#Arginine.) In the presence of H3R2me2a UHRF1 can not bind to a hemimethylated CpG site, and then DNMT1 is not recruited to the site, and the site remains hemimethylated. Upon further rounds of replication the methylated CpG is passively diluted out. PRMT6 is frequently overexpressed in many types of cancer cells. The overexpression of PRMT6 may be a source of DNA demethylation in cancer. | 1 | Applied and Interdisciplinary Chemistry |
To create this effect, a stream of negative muons, most often created by decaying pions, is sent to a block that may be made up of all three hydrogen isotopes (protium, deuterium, and/or tritium), where the block is usually frozen, and the block may be at temperatures of about 3 kelvin (−270 degrees Celsius) or so. The muon may bump the electron from one of the hydrogen isotopes. The muon, 207 times more massive than the electron, effectively shields and reduces the electromagnetic repulsion between two nuclei and draws them much closer into a covalent bond than an electron can. Because the nuclei are so close, the strong nuclear force is able to kick in and bind both nuclei together. They fuse, release the catalytic muon (most of the time), and part of the original mass of both nuclei is released as energetic particles, as with any other type of nuclear fusion. The release of the catalytic muon is critical to continue the reactions. The majority of the muons continue to bond with other hydrogen isotopes and continue fusing nuclei together. However, not all of the muons are recycled: some bond with other debris emitted following the fusion of the nuclei (such as alpha particles and helions), removing the muons from the catalytic process. This gradually chokes off the reactions, as there are fewer and fewer muons with which the nuclei may bond. The number of reactions achieved in the lab can be as high as 150 d–t fusions per muon (average). | 0 | Theoretical and Fundamental Chemistry |
*[https://web.archive.org/web/20050425235816/http://www.romawa.nl/nereus/fuel.html TRISO fuel descripción]
*[http://www.ndt.net/article/wcndt00/papers/idn540/idn540.htm Non-Destructive Examination of SiC Nuclear Fuel Shell using X-Ray Fluorescence Microtomography Technique]
*[http://www.world-nuclear.org/sym/2003/fig-htm/labf5-h.htm GT-MHR fuel compact process]
*[https://web.archive.org/web/20051112023757/http://www.min.uc.edu/nuclear/kadak/sld009.htm Description of TRISO fuel for "pebbles"]
*[http://www.lanl.gov/orgs/nmt/nmtdo/AQarchive/03springsummer/AFCI.html LANL webpage showing various stages of TRISO fuel production]
*[http://www.ijnsweb.com/?type=subscriber&action=articleinfo&id=188 Method to calculate the temperature profile in TRISO fuel] | 0 | Theoretical and Fundamental Chemistry |
Other types of radioactive decay were found to emit previously seen particles but via different mechanisms. An example is internal conversion, which results in an initial electron emission, and then often further characteristic X-rays and Auger electrons emissions, although the internal conversion process involves neither beta nor gamma decay. A neutrino is not emitted, and none of the electron(s) and photon(s) emitted originate in the nucleus, even though the energy to emit all of them does originate there. Internal conversion decay, like isomeric transition gamma decay and neutron emission, involves the release of energy by an excited nuclide, without the transmutation of one element into another.
Rare events that involve a combination of two beta-decay-type events happening simultaneously are known (see below). Any decay process that does not violate the conservation of energy or momentum laws (and perhaps other particle conservation laws) is permitted to happen, although not all have been detected. An interesting example discussed in a final section, is bound state beta decay of rhenium-187. In this process, the beta electron-decay of the parent nuclide is not accompanied by beta electron emission, because the beta particle has been captured into the K-shell of the emitting atom. An antineutrino is emitted, as in all negative beta decays.
If energy circumstances are favorable, a given radionuclide may undergo many competing types of decay, with some atoms decaying by one route, and others decaying by another. An example is copper-64, which has 29 protons, and 35 neutrons, which decays with a half-life of hours. This isotope has one unpaired proton and one unpaired neutron, so either the proton or the neutron can decay to the other particle, which has opposite isospin. This particular nuclide (though not all nuclides in this situation) is more likely to decay through beta plus decay (%) than through electron capture (%). The excited energy states resulting from these decays which fail to end in a ground energy state, also produce later internal conversion and gamma decay in almost 0.5% of the time. | 0 | Theoretical and Fundamental Chemistry |
Calthemite coralloids (also known as popcorn), can form on the underside of concrete structures and look very similar to those which occurs in caves. Coralloids can form by a number of different methods in caves, however on concrete the most common form is created when hyperalkaline solution seeps from fine cracks in concrete. Due to solution evaporation, deposition of calcium carbonate occurs before any drop can form. The resulting coralloids are small and chalky with a cauliflower appearance. | 1 | Applied and Interdisciplinary Chemistry |
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