text stringlengths 105 4.57k | label int64 0 1 | label_text stringclasses 2
values |
|---|---|---|
If the values of the predicted rate constants are compared with the values of known rate constants, it is noticed that collision theory fails to estimate the constants correctly, and the more complex the molecules are, the more it fails. The reason for this is that particles have been supposed to be spherical and able to react in all directions, which is not true, as the orientation of the collisions is not always proper for the reaction. For example, in the hydrogenation reaction of ethylene the H molecule must approach the bonding zone between the atoms, and only a few of all the possible collisions fulfill this requirement.
To alleviate this problem, a new concept must be introduced: the steric factor ρ. It is defined as the ratio between the experimental value and the predicted one (or the ratio between the frequency factor and the collision frequency):
and it is most often less than unity.
Usually, the more complex the reactant molecules, the lower the steric factor. Nevertheless, some reactions exhibit steric factors greater than unity: the harpoon reactions, which involve atoms that exchange electrons, producing ions. The deviation from unity can have different causes: the molecules are not spherical, so different geometries are possible; not all the kinetic energy is delivered into the right spot; the presence of a solvent (when applied to solutions), etc.
Collision theory can be applied to reactions in solution; in that case, the solvent cage has an effect on the reactant molecules, and several collisions can take place in a single encounter, which leads to predicted preexponential factors being too large. ρ values greater than unity can be attributed to favorable entropic contributions. | 0 | Theoretical and Fundamental Chemistry |
The Stefan flow, occasionally called Stefan's flow, is a transport phenomenon concerning the movement of a chemical species by a flowing fluid (typically in the gas phase) that is induced to flow by the production or removal of the species at an interface. Any process that adds the species of interest to or removes it from the flowing fluid may cause the Stefan flow, but the most common processes include evaporation, condensation, chemical reaction, sublimation, ablation, adsorption, absorption, and desorption. It was named after the Slovenian physicist, mathematician, and poet Josef Stefan for his early work on calculating evaporation rates.
The Stefan flow is distinct from diffusion as described by Fick's law, but diffusion almost always also occurs in multi-species systems that are experiencing the Stefan flow. In systems undergoing one of the species addition or removal processes mentioned previously, the addition or removal generates a mean flow in the flowing fluid as the fluid next to the interface is displaced by the production or removal of additional fluid by the processes occurring at the interface. The transport of the species by this mean flow is the Stefan flow. When concentration gradients of the species are also present, diffusion transports the species relative to the mean flow. The total transport rate of the species is then given by a summation of the Stefan flow and diffusive contributions.
An example of the Stefan flow occurs when a droplet of liquid evaporates in air. In this case, the vapor/air mixture surrounding the droplet is the flowing fluid, and liquid/vapor boundary of the droplet is the interface. As heat is absorbed by the droplet from the environment, some of the liquid evaporates into vapor at the surface of the droplet, and flows away from the droplet as it is displaced by additional vapor evaporating from the droplet. This process causes the flowing medium to move away from the droplet at some mean speed that is dependent on the evaporation rate and other factors such as droplet size and composition. In addition to this mean flow, a concentration gradient must exist in the neighborhood of the droplet (assuming an isolated droplet) since the flowing medium is mostly air far from the droplet and mostly vapor near the droplet. This gradient causes Fickian diffusion that transports the vapor away from the droplet and the air towards it, with respect to the mean flow. Thus, in the frame of the droplet, the flow of vapor away from the droplet is faster than for the pure Stefan flow, since diffusion is working in the same direction as the mean flow. However, the flow of air away from the droplet is slower than the pure Stefan flow, since diffusion is working to transport air back towards the droplet against the Stefan flow. Such flow from evaporating droplets is important in understanding the combustion of liquid fuels such as diesel in internal combustion engines, and in the design of such engines. The Stefan flow from evaporating droplets and subliming ice particles also plays prominently in meteorology as it influences the formation and dispersion of clouds and precipitation. | 1 | Applied and Interdisciplinary Chemistry |
Waves varying sinusoidal in time, with period are considered. That is
where is the amplitude, is the wave height, is the angular frequency and is the wave phase. Consequently, also in Eq. () has to be a sine wave, e.g. with a constant.
Applying these forms of and in Eq. () gives:
which is Greens law'. | 1 | Applied and Interdisciplinary Chemistry |
The ionic strength plays a central role in the Debye–Hückel theory that describes the strong deviations from ideality typically encountered in ionic solutions. It is also important for the theory of double layer and related electrokinetic phenomena and electroacoustic phenomena in colloids and other heterogeneous systems. That is, the Debye length, which is the inverse of the Debye parameter (κ), is inversely proportional to the square root of the ionic strength. Both molar and molal ionic strength have been used, often without explicit definition. Debye length is characteristic of the double layer thickness. Increasing the concentration or valence of the counterions compresses the double layer and increases the electrical potential gradient.
Media of high ionic strength are used in stability constant determination in order to minimize changes, during a titration, in the activity quotient of solutes at lower concentrations. Natural waters such as mineral water and seawater have often a non-negligible ionic strength due to the presence of dissolved salts which significantly affects their properties. | 0 | Theoretical and Fundamental Chemistry |
Her publications include;
Casini serves on the editorial board of the Journal of Biological Inorganic Chemistry and the Journal of Inorganic Biochemistry. | 0 | Theoretical and Fundamental Chemistry |
Tacticity describes the relative stereochemistry of chiral centers in neighboring structural units within a macromolecule. There are three types of tacticity: isotactic (all substituents on the same side), atactic (random placement of substituents), and syndiotactic (alternating placement of substituents). | 0 | Theoretical and Fundamental Chemistry |
A naive (or inexperienced) B cell is one which belongs to a clone which has never encountered the epitope to which it is specific. In contrast, a memory B cell is one which derives from an activated naive or memory B cell. The activation of a naive or a memory B cell is followed by a manifold proliferation of that particular B cell, most of the progeny of which terminally differentiate into plasma B cells; the rest survive as memory B cells. So, when the naive cells belonging to a particular clone encounter their specific antigen to give rise to the plasma cells, and also leave a few memory cells, this is known as the primary immune response. In the course of proliferation of this clone, the B cell receptor genes can undergo frequent (one in every two cell divisions) mutations in the genes coding for paratopes of antibodies. These frequent mutations are termed somatic hypermutation. Each such mutation alters the epitope-binding ability of the paratope slightly, creating new clones of B cells in the process. Some of the newly created paratopes bind more strongly to the same epitope (leading to the selection of the clones possessing them), which is known as affinity maturation. Other paratopes bind better to epitopes that are slightly different from the original epitope that had stimulated proliferation. Variations in the epitope structure are also usually produced by mutations in the genes of pathogen coding for their antigen. Somatic hypermutation, thus, makes the B cell receptors and the soluble antibodies in subsequent encounters with antigens, more inclusive in their antigen recognition potential of altered epitopes, apart from bestowing greater specificity for the antigen that induced proliferation in the first place. When the memory cells get stimulated by the antigen to produce plasma cells (just like in the clones primary response), and leave even more memory cells in the process, this is known as a secondary immune response,' which translates into greater numbers of plasma cells and faster rate of antibody production lasting for longer periods. The memory B cells produced as a part of secondary response recognize the corresponding antigen faster and bind more strongly with it (i.e., greater affinity of binding) owing to affinity maturation. The soluble antibodies produced by the clone show a similar enhancement in antigen binding. | 1 | Applied and Interdisciplinary Chemistry |
Glaucoma is caused by high intra-ocular pressure (IOP). β-blockers reduce IOP and are the most common therapy. Most of the patients, who use the topical β-blockers, need adjunctive therapy to achieve a target IOP lowering. One of the most used drug in adjunctive therapy is dorzolamide. | 1 | Applied and Interdisciplinary Chemistry |
*Wax, used in the packaging of frozen foods, among others, Paraffin wax, derived from petroleum oil.
* Sulfur and its derivative sulfuric acid. Hydrogen sulfide is a product of sulfur removal from petroleum fraction. It is oxidized to elemental sulfur and then to sulfuric acid.
* Bulk tar and Asphalt
* Petroleum coke, used in speciality carbon products or as solid fuel | 0 | Theoretical and Fundamental Chemistry |
Complex molecules, in particular those containing carbon can be in the form of stereoisomers. With abiotic processes they would be expected to be equally likely, but in carbonaceous chondrites this is not the case. The reasons for this are unknown. | 0 | Theoretical and Fundamental Chemistry |
DNA molecules contain 5-membered carbon rings called riboses that are directly attached to two phosphate groups and a nucleobase that contains amino groups. The nitrogen atoms from the amino group in the nucleotides are covalently linked to the anomeric carbon of the ribose sugar structure through an N-glycosidic bond. Occasionally, the nucleobases attached to the ribose undergo deamination, alkylation, or oxidation which results in cytotoxic lesions along the DNA backbone. These modifications severely threaten the cohesiveness of the DNA molecule, leading to the development of diseases such as cancer. DNA glycosylases are enzymes that catalyze the hydrolysis the N-glycosidic bond to free the damaged or modified nucleobase from the DNA, by cleaving the carbon-nitrogen glycosidic bond at the 2' carbon, subsequently initiating the base excision repair (BER) pathway.
Monofunctional glycosylases catalyze the hydrolysis of the N-glycosidic bond via either a stepwise, S1 like mechanism, or a concerted, S2 like mechanism. The stepwise function, the nucleobase acts as a leaving group before the anomeric carbon gets attacked by the water molecule, producing a short-lived unstable oxacarbenium ion intermediate. This intermediate rapidly reacts with the nearby water molecule to substitute the N-glycosidic bond of the ribose and the nucleobase with an O-glycosidic bond with a hydroxy group. The concerted mechanism, the water acts as a nucleophile and attacks at the anomeric carbon before the nucelobase gets to act like a leaving group. The intermediate produced is a similar oxacarbenium ion where both the hydroxy groups and the nucleobase are still attached to the anomeric carbon. Both mechanisms theoretically yield the same product. Most ribonucleotides are hydrolyzed via the concerted S2 like mechanism, while most deoxyribonucleotides proceed through the stepwise like mechanism.
These reactions are practically irreversible. Due to the fact that the cleavage of the N-glycosidic bond from the DNA backbone can lead to detrimental mutagenic and cytotoxic responses in an organism, have the ability to also catalyze the synthesis of N-glycosidic bonds by way of an abasic DNA site and a specific nucleobase. | 0 | Theoretical and Fundamental Chemistry |
Putative genes can be identified by clustering large groups of sequences by patterns and arranging by mutual similarity or can be inferred by potential TATA boxes.
Putative genes can also be identified by recognizing differences between well-known gene clusters and gene clusters with a unique profiling.
Software tools have been developed in order to automatically identify putative genes. This is done by searching for gene families and testing the validity of uncharacterized genes by comparison to already identified genes.
Protein products can be identified and used to characterize the putative gene that codes for it. | 1 | Applied and Interdisciplinary Chemistry |
The process of histamine inactivation in biological species involves its metabolism through the oxidative deamination of its primary amino group. This reaction is catalyzed by the enzyme diamine oxidase (DAO). The metabolite produced from this reaction is imidazole-4-acetaldehyde.
Imidazole-4-acetaldehyde is then further oxidized by a NAD-dependent aldehyde dehydrogenase, leading to imidazole-4-acetic acid. | 1 | Applied and Interdisciplinary Chemistry |
* Lee, Y. T. "Crossed Molecular Beam Studies and Dynamics of Decomposition of Chemically Activated Radicals", University of Chicago, United States Department of Energy (through predecessor agency the Atomic Energy Commission), (September 1973).
* Lee, Y. T. & S. J. Sibener. "Internal Energy Dependence of Molecular Condensation Coefficients Determined from Molecular Beam Surface Scattering Experiments", Lawrence Berkeley Laboratory, University of California, Berkeley, United States Department of Energy, (May 1978).
* Lee, Y. T., Sibener, S. J. & R. J. Buss. "Development of a Supersonic Atomic Oxygen Nozzle Beam Source for Crossed Beam Scattering Experiments", Lawrence Berkeley Laboratory, University of California, Berkeley, United States Department of Energy, (May 1978).
* Lee, Y. T., Baseman, R. J., Guozhong, H. & R. J. Buss. "Reaction Mechanism of Oxygen Atoms with Unsaturated Hydrocarbons by the Crossed-Molecular-Beams Method", Lawrence Berkeley Laboratory, University of California, Berkeley, United States Department of Energy-Office of Basic Energy Science, (April 1982).
* Lee, Y. T. "Molecular-beam Studies of Primary Photochemical Processes", Lawrence Berkeley Laboratory, University of California, Berkeley, United States Department of Energy, (December 1982).
* Lee, Y. T., Continetti, R. E. & B. A. Balko. "Molecular Beam Studies of Hot Atom Chemical Reactions: Reactive Scattering of Energetic Deuterium Atoms", Lawrence Berkeley Laboratory, United States Department of Energy, (February 1989).
* Lee, Y.T., "Energy, Environment, and the Responsibility of Scientists", (2007). | 0 | Theoretical and Fundamental Chemistry |
Gas phase coating is carried out at higher temperatures, about 1080 °C. The coating material is usually loaded onto trays without physical contact with the parts to be coated. The coating mixture contains active coating material and activator, but usually not thermal ballast. As in the pack cementation process, gaseous aluminium chloride (or fluoride) is transferred to the surface of the part. However, in this case the diffusion is outwards. This kind of coating also requires diffusion heat treatment. | 1 | Applied and Interdisciplinary Chemistry |
For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For potassium labeling purposes 100% of the Daily Value was 3500 mg, but as of May 2016, it has been revised to 4700 mg. A table of the old and new adult Daily Values is provided at Reference Daily Intake. | 1 | Applied and Interdisciplinary Chemistry |
The convection–diffusion equation (with no sources or drains, ) can be viewed as a stochastic differential equation, describing random motion with diffusivity and bias . For example, the equation can describe the Brownian motion of a single particle, where the variable describes the probability distribution for the particle to be in a given position at a given time. The reason the equation can be used that way is because there is no mathematical difference between the probability distribution of a single particle, and the concentration profile of a collection of infinitely many particles (as long as the particles do not interact with each other).
The Langevin equation describes advection, diffusion, and other phenomena in an explicitly stochastic way. One of the simplest forms of the Langevin equation is when its "noise term" is Gaussian; in this case, the Langevin equation is exactly equivalent to the convection–diffusion equation. However, the Langevin equation is more general. | 1 | Applied and Interdisciplinary Chemistry |
Trimethylsilyl azide is the organosilicon compound with the formula . A colorless liquid, it is a reagent in organic chemistry, serving as the equivalent of hydrazoic acid. | 0 | Theoretical and Fundamental Chemistry |
Willauer started researching biphasic systems and phase transitions after graduating from Berry College. In 1998 she studied aqueous biphasic systems (ABS) for the potential of recapturing valuable dyes from textile manufacturing effluent. She investigated ions and catalysts.
In the 2000s, Willauer began studying methods for extracting CO and H from seawater, for the purpose of reacting these molecules into hydrocarbons by using the Fischer–Tropsch process. She also investigated modified iron (Fe) catalysts and studied zeolite (nanoporous aluminosilicate) catalyst supports for recombining these molecules into jet fuel.
Previous studies had concluded that CO, under the form of the bicarbonate anion (HCO) dominant (96% mole fraction) in the seawater inorganic carbon species could not be economically removed from seawater. However, by acidifying seawater by means of an adapted electrolysis cell with cation permeable membranes (dubbed a three-chambered electrochemical acidification cell), it is possible to economically convert HCO into CO at a pH lower than 6 and to increase the extraction yield. In January 2011, the NRL installed a prototype of seawater electrolysis cell at Naval Air Station Key West in Florida.
In 2017, Willauer et al. were granted a patent for a extraction device from seawater, in the form of an electrolytic-cation exchange module (E-CEM). The E-CEM is seen as a "key step" in the production of synthetic fuel from seawater. Other researchers named in the patent are Felice DiMascio, Dennis R. Hardy, Jeffrey Baldwin, Matthew Bradley, James Morris, Ramagopal Ananth and Frederick W. Williams. | 0 | Theoretical and Fundamental Chemistry |
Proteins are essential macromolecules of living organisms. They are continuously being degraded into their constituent amino acids which can be reused in the synthesis of new proteins. Every cellular protein has its own half-life time. In humans, for instance, 50% of the liver and plasma proteins are replaced in 10 days, whereas in muscles it takes 180 days. In average, every 80 days about 50% of our proteins are totally replaced. Although the regulation of protein degradation is as important as their synthesis to keep each cell protein concentration at the optimum level, research in this area remained until the end of the 1970s. Up to this time, lysosomes, discovered in the 1950s by the Belgian cytologist Christian de Duve, were thought responsible for the complete digestion of intra- and extracellular proteins by the lysosomal hydrolytic enzymes.
Between the 1970s and 1980s, this view drastically changed. New experimental evidences showed that, under physiological conditions, non-lysosomal proteases were responsible for limited proteolysis of intra- and/or extracellular proteins, a concept originally conceived by Linderstᴓm-Lang in 1950. Endogenous or exogenous proteins are processed by non-lysosomal proteases into intermediate-sized polypeptides, which display gene and metabolic regulation, neurologic, endocrine, and immunological roles, whose dysfunction might explain a number of pathologies. Consequently, protein degradation did not represent anymore the end of the biological function of proteins, but rather the beginning of a yet unexplored side of the biology of the cells. A number of intra- or extracellular proteases release protein fragments endowed with essential biological activities. These hydrolytic processes could be carried out by proteases such as Proteasomes, Proprotein Convertases, Caspases, Rennin and Kallikreins. Among the products released by the non-lysosomal proteases are the bioactive oligopeptides such as hormones, neuropeptides and epitopes that, once released, could be modulated in their biological activities by specific peptidases, which promote the trimming, conversion and/or inactivation of the bioactive oligopeptides. | 1 | Applied and Interdisciplinary Chemistry |
The speed of sound varies with temperature. Since temperature and sound velocity normally decrease with increasing altitude, sound is refracted upward, away from listeners on the ground, creating an acoustic shadow at some distance from the source. Wind shear of 4 m/(s · km) can produce refraction equal to a typical temperature lapse rate of . Higher values of wind gradient will refract sound downward toward the surface in the downwind direction, eliminating the acoustic shadow on the downwind side. This will increase the audibility of sounds downwind. This downwind refraction effect occurs because there is a wind gradient; the fact that sound is carried along by the wind is not important.
For sound propagation, the exponential variation of wind speed with height can be defined as follows:
where
* U(h) is the speed of the wind at height h;
* ζ is the exponential coefficient based on ground surface roughness, typically between 0.08 and 0.52;
* dU/dH(h) is the expected wind gradient at height h.
In the 1862 American Civil War Battle of Iuka, an acoustic shadow, believed to have been enhanced by a northeast wind, kept two divisions of Union soldiers out of the battle, because they could not hear the sounds of battle only (six miles) downwind. | 1 | Applied and Interdisciplinary Chemistry |
The full biosynthesis of Absinthin in Artemisia absinthium has not been elucidated, but a great portion of it can be inferred from the natural product precursors required to access Absinthin. While terpenoids like Absinthin can be said to consist of isoprene "units," isoprene by itself is too stable and does not react directly. Rather, the isoprene units are transferred and reacted as diphosphates. As the nomenclature for terpenes suggests, the first Absinthin precursor farnesyl diphosphate [A] contains 15 carbons, or 3 isoprene units. Diphosphate departure (1) generates a carbo-cation within the synthase, which can then be attacked by a carbon-carbon double bond at the opposing end of the molecule (2). The first stable intermediate in the biosynthesis pathway in Artemisia is likely Germacrene A [B], which has been previously identified in plant sesquiterpene pathways as a precursor to guaianolides. From there, hydroxylation (3) occurs, followed by oxidation (4) to an aldehyde directly followed by further hydroxylation (5) and formation of a carboxyl group. It is important to note the disappearance of the terminal carbon-carbon double bond after (4), as the reduction of this bond in the final product differentiates the Absinthin monomer from other Germacrene A downstream products. This reduction does not necessarily occur at step (4), but may occur further downstream. With the carboxyl and hydroxyl group in position, the guaiano-lactone [C] formation via dehydration (7) can occur, as proposed for a general guaianolide pathway. Formation of the Absinthin sesquiterpene guaianolide monomer [D] from hydroxylation and double bond rearrangement (8,9) is then postulated to directly precede dimerization to Absinthin [E] via a naturally occurring Diels-Alder reaction [10], which is likely facilitated by the associated synthase even though the reaction itself can occur in good yields spontaneously, albeit slower than typical natural product biosynthesis.
While no synthases specific to Artemisia absinthium have been sufficiently isolated to recreate this particular sesquiterpene formation in vitro, the general reaction scheme presented here portrays a likely scenario for Absinthin biosynthesis through the use of terpene intermediates utilized in the biosynthesis of Germacrene A, another sesquiterpene lactone. Enzymatic analogs from terpene biosynthesis which help rationalize the above proposed numbered biosynthetic steps are as follows:
# Farnesyl diphosphate departure via a generic sesquiterpene synthase
# Ring closure via a generic sesquiterpene synthase (as for #1)
# Hydroxylation of terminal allylic carbon via Germacrene A hydroxylase, a cytochrome P450 enzyme.
# Oxidation of alcohol to aldol, via -germacrene A hydroxylase.
# Hydroxylation of alcohol to carboxyl group, via Germacrene A hydroxylase.
# NADPH-mediated hydroxylation of allylic carbon via a postulated hydroxylation to precede lactone ring closure
# Lactone formation/ring closure
# Hydroxylation at carbon-carbon tertiary double bond.
# Additional 5-membered ring formation/cyclization
# Diels-Alder coupling via an unidentified enzyme in Artemisia absinthium. | 0 | Theoretical and Fundamental Chemistry |
*Edgar Fahs Smith Memorial Collection in the history of chemistry at the University of Pennsylvania, opened in 1931
*Discovery of helium in natural gas by Hamilton Cady and David Ford McFarland at the University of Kansas in 1905
*Isolation of organic free radicals by Moses Gomberg at the University of Michigan in 1900
*Discovery of new elements beyond Curium by researchers at the Lawrence Berkeley National Laboratory in Berkeley, California
*Bowood House in Wiltshire, U.K., site of Joseph Priestley's discovery of oxygen in 1774
*Nucleic acid and protein chemistry at Rockefeller University
*Wallace Carothers' research on polymers at DuPont between 1928 and 1937 | 1 | Applied and Interdisciplinary Chemistry |
Some forensic techniques, believed to be scientifically sound at the time they were used, have turned out later to have much less scientific merit or none. Some such techniques include:
* Comparative bullet-lead analysis was used by the FBI for over four decades, starting with the John F. Kennedy assassination in 1963. The theory was that each batch of ammunition possessed a chemical makeup so distinct that a bullet could be traced back to a particular batch or even a specific box. Internal studies and an outside study by the National Academy of Sciences found that the technique was unreliable due to improper interpretation, and the FBI abandoned the test in 2005.
* Forensic dentistry has come under fire: in at least three cases bite-mark evidence has been used to convict people of murder who were later freed by DNA evidence. A 1999 study by a member of the American Board of Forensic Odontology found a 63 percent rate of false identifications and is commonly referenced within online news stories and conspiracy websites. The study was based on an informal workshop during an ABFO meeting, which many members did not consider a valid scientific setting. The theory is that each person has a unique and distinctive set of teeth, which leave a pattern after biting someone. They analyze the dental characteristics such as size, shape, and arch form.
* In 2009, scientists were able to show that it is possible to fabricate DNA evidence, thus "undermining the credibility of what has been considered the gold standard of proof in criminal cases".
* Police Access to Genetic Genealogy Databases: There are privacy concerns with the police being able to access personal genetic data that is on genealogy services. Individuals can become criminal informants to their own families or to themselves simply by participating in genetic genealogy databases. The Combined DNA Index System (CODIS) is a database that the FBI uses to hold genetic profiles of all known felons, misdemeanants, and arrestees. Some people argue that individuals who are using genealogy databases should have an expectation of privacy in their data that is or may be violated by genetic searches by law enforcement. These different services have warning signs about potential third parties using their information, but most individuals do not read the agreement thoroughly. According to a study by Christi Guerrini, Jill Robinson, Devan Petersen, and Amy McGuire, they found that the majority of the people who took the survey support police searches of genetic websites that identify genetic relatives. People who responded to the survey are more supportive of police activities using genetic genealogy when it is for the purpose of identifying offenders of violent crimes, suspects of crimes against children or missing people. The data from the surveys that were given show that individuals are not concerned about police searches using personal genetic data if it is justified. It was found in this study that offenders are disproportionally low-income and black and the average person of genetic testing is wealthy and white. The results from the study had different results. In 2016, there was a survey called the National Crime Victimization Survey (NCVS) that was provided by the US Bureau of Justice Statistics. In that survey, it was found that 1.3% of people aged 12 or older were victims of violent crimes, and 8.85 of households were victims of property crimes. There were some issues with this survey though. The NCVS produces only the annual estimates of victimization. The survey that Christi Guerrini, Jill Robinson, Devan Petersen, and Amy McGuire produced asked the participants about the incidents of victimization over one's lifetime. Their survey also did not restrict other family members to one household. Around 25% of people who responded to the survey said that they have had family members that have been employed by law enforcement which includes security guards and bailiffs. Throughout these surveys, it has been found that there is public support for law enforcement to access genetic genealogy databases. | 0 | Theoretical and Fundamental Chemistry |
Radicals are highly reactive and short-lived, as they have an unpaired electron which makes it extremely unstable. Radicals often react with hydrogens attached carbon molecules, effectively making the carbon a radical while stabilizing the former radical in a process called propagation. The formed product, a carbon radical, can react with non-radical molecule to continue propagation or react with another radical to form a new stable molecule such as a longer carbon chain or an alkyl halide.
The example below of methane chlorination shows a multi-step reaction involving radicals. | 0 | Theoretical and Fundamental Chemistry |
__NOTOC__
A trace element is a chemical element of a minute quantity, a trace amount, especially used in referring to a micronutrient, but is also used to refer to minor elements in the composition of a rock, or other chemical substance.
In nutrition, trace elements are classified into two groups: essential trace elements, and non-essential trace elements. Essential trace elements are needed for many physiological and biochemical processes in both plants and animals. Not only do trace elements play a role in biological processes but they also serve as catalysts to engage in redox – oxidation and reduction mechanisms. Trace elements of some heavy metals have a biological role as essential micronutrients. | 0 | Theoretical and Fundamental Chemistry |
Axelopran is an oral PAMORA which is under development by Theravane Biopharma. It has completed phase II in clinical trials in more than 400 patients with OIC. Axelopran has a different chemical structure from other PAMORAs but with a similar mechanism of action. It acts as an antagonist for MOR, KOR and DOR, but with higher affinity for MOR and KOR than for DOR. Like other PAMORAs, the main goal is the treatment of OIC.
Axelopran is also being investigated in fixed-dose combination (FDC) with oxycodone. It is done by using spray coating technology to create an FDC of axelopran and controlled-release oxycodone.
There is a demand for optimization of the receptor selectivity and affinity accompanied by an exploration of candidate compounds regarding their route of administration. These are the main objectives and future strategies for drug discovery and the development of PAMORAs.
Predominantly, the MORs exhibit functionally selective agonism. Therefore, future possible candidate compounds that target OIC are PAMORAs with optimized selectivity and affinity. | 1 | Applied and Interdisciplinary Chemistry |
On scales greater than 10 years, fission products, chiefly Tc, again represent a significant proportion of the remaining, though lower radioactivity, along with longer-lived actinides like neptunium-237 and plutonium-242, if those have not been destroyed.
The most abundant long-lived fission products have total decay energy around 100–300 keV, only part of which appears in the beta particle; the rest is lost to a neutrino that has no effect. In contrast, actinides undergo multiple alpha decays, each with decay energy around 4–5 MeV.
Only seven fission products have long half-lives, and these are much longer than 30 years, in the range of 200,000 to 16 million years. These are known as long-lived fission products (LLFP). Three have relatively high yields of about 6%, while the rest appear at much lower yields. (This list of seven excludes isotopes with very slow decay and half-lives longer than the age of the universe, which are effectively stable and already found in nature, as well as a few nuclides like technetium-98 and samarium-146 that are "shadowed" from beta decay and can only occur as direct fission products, not as beta decay products of more neutron-rich initial fission products. The shadowed fission products have yields on the order of one millionth as much as iodine-129.) | 0 | Theoretical and Fundamental Chemistry |
Within set concrete there remains some free "calcium hydroxide" (Ca(OH)), which can further dissociate to form Ca and hydroxide (OH) ions". Any water which finds a seepage path through micro cracks and air voids present in concrete, will readily carry the (Ca(OH)) and Ca (depending on solution pH and chemical reaction at the time) to the underside of the structure where leachate solution contacts the atmosphere. Carbon dioxide (CO) from the atmosphere readily diffuses into the leachate and causes a chemical reaction, which precipitates (deposits) calcium carbonate (CaCO) on the outside of the concrete structure. Consisting primarily of CaCO this secondary deposit derived from concrete is known as "calthemite" and can mimic the shapes and forms of cave "speleothems", such as stalactites, stalagmites, flowstone etc. Other trace elements such as iron from rusting reinforcing steel bars may be transported and deposited by the leachate at the same time as the CaCO. This may colour the calthemites orange or red.
The chemistry involving the leaching of calcium hydroxide from concrete can facilitate the growth of calthemites up to ≈200 times faster than cave speleothems due to the different chemical reactions involved. The sight of calthemite is a visual sign that calcium is being leached from the concrete structure and the concrete is gradually degrading.
In very old concrete where the calcium hydroxide has been leached from the leachate seepage path, the chemistry may revert to that similar to "speleothem" chemistry in limestone cave. This is where carbon dioxide enriched rain or seepage water forms a weak carbonic acid, which leaches calcium carbonate (CaCO) from within the concrete structure and carries it to the underside of the structure. When it contacts the atmosphere, carbon dioxide degasses and calcium carbonate is precipitated to create calthemite deposits, which mimic the shapes and forms of speleothems. This degassing chemistry is not common in concrete structures as the leachate can often find new paths through the concrete to access free calcium hydroxide and this reverts the chemistry to that previously mentioned where CO is the reactant. | 1 | Applied and Interdisciplinary Chemistry |
In macromolecular crystallography, the term additive is used instead of adjutant. An additive can either interact directly with the protein, and become incorporated at a fixed position in the resulting crystal or have a role within the disordered solvent, that in protein crystals constitute roughly 50% of the lattice volume.
Polyethylene glycols of various molecular weights and high-ionic strength salts such as ammonium sulfate and sodium citrate that induce protein precipitation when used in high concentrations are classified as precipitants, while certain other salts such as zinc sulfate or calcium sulfate that may cause a protein to precipitate vigorously even when used in small amounts are considered adjutants. Crystallization adjutants are considered additives when they are effective at relatively low concentrations.
The distinction between buffers and adjutants is also fuzzy. Buffer molecules can become part of the lattice (for example HEPES in becomes incorporated in crystals of human neutrophil collagenase) but their main use is to maintain the rather precise pH requirements for crystallization that many proteins have. Commonly used buffers such as citrate have a high ionic strength and at the typical buffer concentrations they also act as precipitants. Various species such as Ca and Zn are a biological requirement for certain proteins to fold correctly and certain co-factors are needed to maintain a well defined conformation. Certain strategies, like replacing precipitants and buffers with others intended to have a similar effect, have been used to differentiate between the roles played in protein crystallization by the various components in the crystallization solution. | 0 | Theoretical and Fundamental Chemistry |
The strength of a carboxylic acid depends on the extent of its ionization constant: the more ionized it is, the stronger it is. As an acid becomes stronger, the numerical value of its acid dissociation constant| drops.
In acids, the electron-releasing inductive effect of the alkyl group increases the electron density on oxygen and thus hinders the breaking of the O-H bond, which consequently reduces the ionization. Due to its greater ionization, formic acid () is stronger than acetic acid (). Monochloroacetic acid (), though, is stronger than formic acid, due to the electron-withdrawing effect of chlorine promoting ionization.
In benzoic acid, the carbon atoms which are present in the ring are sp hybridised. As a result, benzoic acid () is a stronger acid than cyclohexanecarboxylic acid (). Also, in aromatic carboxylic acids, electron-withdrawing groups substituted at the ortho and para positions can enhance the acid strength.
Since the carboxyl group is itself an electron-withdrawing group, dicarboxylic acids are, in general, stronger acids than their monocarboxyl analogues.
The Inductive effect will also help in polarization of a bond making certain carbon atom or other atom positions. | 0 | Theoretical and Fundamental Chemistry |
Systemic agmatine can potentiate opioid analgesia and prevent tolerance to chronic morphine in laboratory rodents. Since then, cumulative evidence amply shows that agmatine inhibits opioid dependence and relapse in several animal species. | 1 | Applied and Interdisciplinary Chemistry |
A proton pump is any process that creates a proton gradient across a membrane. Protons can be physically moved across a membrane, as seen in mitochondrial Complexes I and IV. The same effect can be produced by moving electrons in the opposite direction. The result is the disappearance of a proton from the cytoplasm and the appearance of a proton in the periplasm. Mitochondrial Complex III is this second type of proton pump, which is mediated by a quinone (the Q cycle).
Some dehydrogenases are proton pumps, while others are not. Most oxidases and reductases are proton pumps, but some are not. Cytochrome bc is a proton pump found in many, but not all, bacteria (not in E. coli). As the name implies, bacterial bc is similar to mitochondrial bc (Complex III). | 1 | Applied and Interdisciplinary Chemistry |
Direct reduction processes were developed to overcome the difficulties of conventional blast furnaces. DRI plants need not be part of an integrated steel plant, as is characteristic of blast furnaces. The initial capital investment and operating costs of direct reduction plants are lower than integrated steel plants and are more suitable for developing countries where supplies of high grade coking coal are limited, but where steel scrap is generally available for recycling. Many other countries use variants of the process.
Factors that help make DRI economical:
* Direct-reduced iron has about the same iron content as pig iron, typically 90–94% total iron (depending on the quality of the raw ore) so it is an excellent feedstock for the electric furnaces used by mini mills, allowing them to use lower grades of scrap for the rest of the charge or to produce higher grades of steel.
* Hot-briquetted iron (HBI) is a compacted form of DRI designed for ease of shipping, handling, and storage.
* Hot direct reduced iron (HDRI) is DRI that is transported hot, directly from the reduction furnace, into an electric arc furnace, thereby saving energy.
* The direct reduction process uses pelletized iron ore or natural "lump" ore. One exception is the fluidized bed process which requires sized iron ore particles.
* The direct reduction process can use natural gas contaminated with inert gases, avoiding the need to remove these gases for other use. However, any inert gas contamination of the reducing gas lowers the effect (quality) of that gas stream and the thermal efficiency of the process. The use of natural gas also produces greenhouse gases.
* Supplies of powdered ore and raw natural gas are both available in areas such as Northern Australia, avoiding transport costs for the gas. In most cases the DRI plant is located near a natural gas source as it is more cost effective to ship the ore rather than the gas.
* To eliminate fossil fuel use in iron and steel making, renewable hydrogen gas can be used in place of syngas to produce DRI and eliminate production of greenhouse gases. | 1 | Applied and Interdisciplinary Chemistry |
Pycnonuclear reactions can occur anywhere and in any matter, but under standard conditions, the speed of the reaction is exceedingly low, and thus, have no significant role outside of extremely dense systems, neutron-rich and free electron-rich environments, such as the inner crust of a neutron star. A feature of pycnonuclear reactions is that the rate of the reaction is directly proportional to the density of the space that the reaction is occurring in, but is almost fully independent of the temperature of the environment.
Pycnonuclear reactions are observed in neutron stars or white dwarfs, with evidence present of them occurring in lab-generated deuterium-tritium plasma. Some speculations also relate the fact that Jupiter emits more radiation than it receives from the Sun with pycnonuclear reactions or cold fusion. | 0 | Theoretical and Fundamental Chemistry |
The cladiellin family of marine natural products possesses interesting molecular architecture, generally containing a 9-membered medium-sized ring. The synthesis of (−)-cladiella-6,11-dien-3-ol allowed access to a variety of other members of the cladiellin family. Notably, the conversion to cladiell-11-ene-3,6,7-triol makes use of macrocyclic stereocontrol in the dihydroxylation of a trisubstituted olefin. Below is shown the synthetic step controlled by the ground state conformation of the macrocycle, allowing stereoselective dihydroxylation without the usage of an asymmetric reagent. This example of substrate controlled addition is an example of the peripheral attack model in which two centers on the molecule are added two at once in a concerted fashion. | 0 | Theoretical and Fundamental Chemistry |
Annealing, in genetics, means for complementary sequences of single-stranded DNA or RNA to pair by hydrogen bonds to form a double-stranded polynucleotide. Before annealing can occur, one of the strands may need to be phosphorylated by an enzyme such as kinase to allow proper hydrogen bonding to occur. The term annealing is often used to describe the binding of a DNA probe, or the binding of a primer to a DNA strand during a polymerase chain reaction. The term is also often used to describe the reformation (renaturation) of reverse-complementary strands that were separated by heat (thermally denatured). Proteins such as RAD52 can help DNA anneal. DNA strand annealing is a key step in pathways of homologous recombination. In particular, during meiosis, synthesis-dependent strand annealing is a major pathway of homologous recombination. | 1 | Applied and Interdisciplinary Chemistry |
Crystal violet is one of the components of methyl violet, a dye first synthesized by Charles Lauth in 1861. From 1866, methyl violet was manufactured by the Saint-Denis-based firm of Poirrier et Chappat and marketed under the name "Violet de Paris". It was a mixture of the tetra-, penta- and hexamethylated pararosanilines.
Crystal violet itself was first synthesized in 1883 by Alfred Kern (1850–1893) working in Basel at the firm of Bindschedler and Busch. To optimize the difficult synthesis which used the highly toxic phosgene, Kern entered into a collaboration with the German chemist Heinrich Caro at BASF. Kern also found that by starting with diethylaniline rather than dimethylaniline, he could synthesize the closely related violet dye now known as C.I. 42600 or C.I. Basic violet 4. | 0 | Theoretical and Fundamental Chemistry |
Aluminium-based nanogalvanic alloys refer to a class of nanostructured metal powders that spontaneously and rapidly produce hydrogen gas upon contact with water or any liquid containing water as a result of their galvanic metal microstructure. It serves as a method of hydrogen production that can take place at a rapid pace at room temperature without the assistance of chemicals, catalysts, or externally supplied power. | 1 | Applied and Interdisciplinary Chemistry |
South Africa has an efficient returnable bottle system which includes beer, spirit and liquor bottles. Bottles and jars manufactured in South Africa contain at least 40% recycled glass. | 0 | Theoretical and Fundamental Chemistry |
Degradation can be detected before serious cracks are seen in a product using infrared spectroscopy. In particular, peroxy-species and carbonyl groups formed by photo-oxidation have distinct absorption bands. | 0 | Theoretical and Fundamental Chemistry |
Some alcohols are reduced to alkanes when treated with hydrosilanes in the presence of a strong Lewis acid. Brønsted acids may also be used. Tertiary alcohols undergo facile reduction using boron trifluoride etherate as the Lewis acid. Primary alcohols require an excess of the silane, a stronger Lewis acid, and long reaction times.
Skeletal rearrangements are sometimes induced. Another side reaction is nucleophilic attack of the conjugate base on the intermediate carbocation. In organosilane reductions of substrates bearing prostereogenic groups, diastereoselectivity is often high. Reduction of either diastereomer of 2-phenyl-2-norbornanol leads exclusively to the endo diastereomer of 2-phenylnorbornane. None of the exo diastereomer was observed.
Allylic alcohols may be deoxygenated in the presence of tertiary alcohols when ethereal lithium perchlorate is employed as a source of Li.
Reductions of alkyl halides and triflates gives poorer yields in general than reductions of alcohols. A Lewis or Bronsted acid is required. | 0 | Theoretical and Fundamental Chemistry |
Reactions of yellow arsenic with the group 6 transition metals largely proceed through thermolytic carbon monoxide elimination in chromium and molybdenum carbonyl complexes. Notable examples include the formation of triple-decker complexes [(CpMo)(μ,η-As)] and [{CpCr}(μ,η-As)] via reaction of the corresponding molybdenum and chromium dimers with yellow arsenic. These remarkable structures feature three planar-rings arranged in parallel fashion to result in an idealized D point group for the chromium complex. Both of these reactions necessitate harsh reaction conditions like boiling xylene to overcome the high barriers to activation of As. Conversely, utilization of more sterically demanding ligands on the metal center enabled reactions in milder conditions with molybdenum and chromium. Cummins Mo(N(t'Bu)Ar) catalyst, also known to split the N-N triple bond in dinitrogen, reacts with yellow arsenic to form a terminal arsenic moiety triple-bonded to the metal center - one of only several compounds known to contain a terminal arsenic atom. Complexes with metal-metal multiple bonds also enable mild As activation parameter. A chromium-chromium quintuply-bonded species reported by Kempe reacts with yellow arsenic to form a crown complex in which the four arsenic atoms form an approximately tetrahedral structure, with each chromium atom bonding to three arsenic atoms. | 0 | Theoretical and Fundamental Chemistry |
Mitochondrial respirometry is used to study mitochondrial functionality in
mitochondrial diseases or diseases with a (suspected) strong link to mitochondria, e.g. diabetes mellitus type 2, obesity and cancer. Other fields of application are e.g. sports science and the connection between mitochondrial function and aging. | 1 | Applied and Interdisciplinary Chemistry |
One of the methods of archaeometallurgy is the study of modern metals and alloys to explain and understand the use of metals in the past. A study conducted by the department of Particle Physics and Astrophysics at Weizmann Institute of Science and the department of Archaeology at the University of Haifia analyzed the chemical composition and the mass of different denominations of Euro coinage. They concluded that even with modern standards and technology, there is a considerable variation within the "same" denomination of coin. This simple conclusion can be used to further analyze discoveries of ancient currency. | 1 | Applied and Interdisciplinary Chemistry |
Because of her interest in nutrition and nutrients, Coward was one of the early adopters of chromatography following its introduction in 1906-1911 by M. S. Tswett.
Carotenoids, a class of structurally similar pigment molecules that include carotenes and xanthophylls, were of particular interest in nutritional research due to their demonstrated importance in animal studies. In his pioneering chromatographic research, Tswett showed the presence of four different xanthophylls in his studies of plant extracts, separated through the use of adsorption chromatography. Following L. S. Palmers descriptions of Tswetts experiment in 1922, Coward replicated the methodology, the results of which she published in 1923. During these studies Coward noted the presence of additional pigment (which would later be determined to be carotenes) in the eluent fractions, nearly developing a chromatographic method for the isolation of vitamin A from the carotenoids. This experiment made her the fifth scientist to adopt the use of chromatography, during a "dormant" period before the techniques popularization in the 1930s.
This early research applying adsorption chromatography would continue in her role at the Royal Pharmaceutical Society, in conjunction with other analytical methods. | 0 | Theoretical and Fundamental Chemistry |
Tetraselenium tetranitride is the inorganic compound with the formula . Like the analogous tetrasulfur tetranitride , is an orange solid. It is however less soluble and more shock-sensitive than .
As determined by X-ray crystallography, adopts a cage structure similar to that of . The Se−Se and Se−N distances are 2.740 and 1.800 Å, respectively. The N−Se−N angles are 90°.
Among its many reactions, reacts with aluminium chloride to form adducts of . | 0 | Theoretical and Fundamental Chemistry |
Chromosome jumping (or chromosome hopping) was first described in 1984 by Collins and Weissman.
At the time, cloning techniques allowed for generation of clones of limited size (up to 240kb), and cytogenetic techniques allowed for mapping such clones to a small region of a particular chromosome to a resolution of around 5-10Mb. Therefore, a major gap remained in resolution between available technologies, and no methods were available for mapping larger areas of the genome. | 1 | Applied and Interdisciplinary Chemistry |
Pdr1p and Pdr3p is a part of Gal4 transcription factor family due to their zinc-finger DNA binding motif, which is located in N-terminus end of Pdr1p. Pdr1p also contains a long internal region of many inhibitory domains and possess a C-terminal transcription activation domain (amino acids 879–1036). The transcriptional activation domain is rich in glutamine and asparagine, which is theorized to facilitate in protein-protein interaction via hydrogen bonding. A study found that DNA-binding domain of Pdr1p was sufficient for recognizing its endogenous target genes. Strong drug resistance phenotype of yeasts with pdr1-3 is speculated due to its inability to bind to ligands that otherwise cause conformational change to inhibit the transcriptional activity of Pdr1p. | 1 | Applied and Interdisciplinary Chemistry |
The gram per cubic centimetre is a unit of density in the CGS system, and is commonly used in chemistry. It is defined by dividing the CGS unit of mass, the gram, by the CGS unit of volume, the cubic centimetre. The official SI symbols are g/cm, g·cm, or g cm. It is equivalent to the units gram per millilitre (g/mL) and kilogram per litre (kg/L). The density of water is about 1 g/cm, since the gram was originally defined as the mass of one cubic centimetre of water at its maximum density at . | 0 | Theoretical and Fundamental Chemistry |
Some industrial-level sprays (with teflon or leather needle packing, variable speed agitator in pressure pot, separate air and fluid pressure regulators) can also be used for Dimetcote. | 1 | Applied and Interdisciplinary Chemistry |
The operation of a detonation gun is a very loud process due to the multiple explosions occurring in the chamber per second. This could cause damage to operators hearing if in close proximity to the D-gun. As a result, detonation spraying should be performed within a sound proof room and no one should be present in the room during operation. Also operators should wear ear protection (such as ear muffs and/or ear plugs) while working with a D-gun. | 1 | Applied and Interdisciplinary Chemistry |
CrysTBox is freely available on demand for non-commercial use by non-commercial subjects. The only safe way to download CrysTBox installers is via a request form on the official website. Commercial use is not allowed due to the license of MATLAB used for CrysTBox compilation. | 0 | Theoretical and Fundamental Chemistry |
In World War I, hydrogen cyanide was used by the French from 1916 as a chemical weapon against the Central Powers, and by the United States and Italy in 1918. It was not found to be effective enough due to weather conditions. The gas is lighter than air and rapidly disperses up into the atmosphere. Rapid dilution made its use in the field impractical. In contrast, denser agents such as phosgene or chlorine tended to remain at ground level and sank into the trenches of the Western Front's battlefields. Compared to such agents, hydrogen cyanide had to be present in higher concentrations in order to be fatal.
A hydrogen cyanide concentration of 100–200 ppm in breathing air will kill a human within 10 to 60 minutes. A hydrogen cyanide concentration of 2000 ppm (about 2380 mg/m) will kill a human in about one minute. The toxic effect is caused by the action of the cyanide ion, which halts cellular respiration. It acts as a non-competitive inhibitor for an enzyme in mitochondria called cytochrome c oxidase. As such, hydrogen cyanide is commonly listed among chemical weapons as a blood agent.
The Chemical Weapons Convention lists it under Schedule 3 as a potential weapon which has large-scale industrial uses. Signatory countries must declare manufacturing plants that produce more than 30 metric tons per year, and allow inspection by the Organisation for the Prohibition of Chemical Weapons.
Perhaps its most infamous use is (German: Cyclone B, with the B standing for – prussic acid; also, to distinguish it from an earlier product later known as Zyklon A), used in Nazi German extermination camps during World War II to kill Jews and other persecuted minorities en masse as part of their Final Solution genocide program. Hydrogen cyanide was also used in the camps for delousing clothing in attempts to eradicate diseases carried by lice and other parasites. One of the original Czech producers continued making Zyklon B under the trademark "Uragan D2" until around 2015.
During World War II, the US considered using it, along with cyanogen chloride, as part of Operation Downfall, the planned invasion of Japan, but President Harry Truman decided against it, instead using the atomic bombs developed by the secret Manhattan Project.
Hydrogen cyanide was also the agent employed in judicial execution in some U.S. states, where it was produced during the execution by the action of sulfuric acid on sodium or potassium cyanide.
Under the name prussic acid, HCN has been used as a killing agent in whaling harpoons, although it proved quite dangerous to the crew deploying it, and it was quickly abandoned. From the middle of the 18th century it was used in a number of poisoning murders and suicides.
Hydrogen cyanide gas in air is explosive at concentrations above 5.6%. | 0 | Theoretical and Fundamental Chemistry |
Hydroacylation as an asymmetric reaction was demonstrated in the form of a kinetic resolution. A true asymmetric synthesis was also described. Both conversions employed rhodium catalysts and a chiral diphosphine ligand. In one application the ligand is Me-DuPhos: | 0 | Theoretical and Fundamental Chemistry |
*1986 – Weissberger-Williams lectureship Award
*1987 – Korean Chemical Society Award
*1989 – Chemical Society of Japan Award
*1995 – DowElanco lectureship Award
*2000 – The H. C. Brown Lecture Award
*2003 – Japan Academy Prize
*2009 – Paul Karrer Gold Medal
*2009 – Special Member of Royal Society of Chemistry (RSC)
*2010 – Nobel Prize in Chemistry
*2010 – Order of Culture
*2010 – Person of Cultural Merit
*2011 – Member of the Japan Academy
*2011 – honored on a stamp issued by Republic of the Congo
*2016 – Honorary chair professorship, National Cheng Kung University | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics the Morison equation is a semi-empirical equation for the inline force on a body in oscillatory flow. It is sometimes called the MOJS equation after all four authors—Morison, O'Brien, Johnson and Schaaf—of the 1950 paper in which the equation was introduced. The Morison equation is used to estimate the wave loads in the design of oil platforms and other offshore structures. | 1 | Applied and Interdisciplinary Chemistry |
It is estimated that half of the US' 1.2M invasive cancer cases diagnosed in 2022 received radiation therapy in their treatment program. Different cancers respond to radiation therapy in different ways.
The response of a cancer to radiation is described by its radiosensitivity.
Highly radiosensitive cancer cells are rapidly killed by modest doses of radiation. These include leukemias, most lymphomas, and germ cell tumors.
The majority of epithelial cancers are only moderately radiosensitive, and require a significantly higher dose of radiation (60–70 Gy) to achieve a radical cure.
Some types of cancer are notably radioresistant, that is, much higher doses are required to produce a radical cure than may be safe in clinical practice. Renal cell cancer and melanoma are generally considered to be radioresistant but radiation therapy is still a palliative option for many patients with metastatic melanoma. Combining radiation therapy with immunotherapy is an active area of investigation and has shown some promise for melanoma and other cancers.
It is important to distinguish the radiosensitivity of a particular tumor, which to some extent is a laboratory measure, from the radiation "curability" of a cancer in actual clinical practice. For example, leukemias are not generally curable with radiation therapy, because they are disseminated through the body. Lymphoma may be radically curable if it is localised to one area of the body. Similarly, many of the common, moderately radioresponsive tumors are routinely treated with curative doses of radiation therapy if they are at an early stage. For example, non-melanoma skin cancer, head and neck cancer, breast cancer, non-small cell lung cancer, cervical cancer, anal cancer, and prostate cancer. With the exception of oligometastatic disease, metastatic cancers are incurable with radiation therapy because it is not possible to treat the whole body.
Modern radiation therapy relies on a CT scan to identify the tumor and surrounding normal structures and to perform dose calculations for the creation of a complex radiation treatment plan. The patient receives small skin marks to guide the placement of treatment fields. Patient positioning is crucial at this stage as the patient will have to be placed in an identical position during each treatment. Many patient positioning devices have been developed for this purpose, including masks and cushions which can be molded to the patient. Image-guided radiation therapy is a method that uses imaging to correct for positional errors of each treatment session.
The response of a tumor to radiation therapy is also related to its size. Due to complex radiobiology, very large tumors respond less well to radiation than smaller tumors or microscopic disease. Various strategies are used to overcome this effect. The most common technique is surgical resection prior to radiation therapy. This is most commonly seen in the treatment of breast cancer with wide local excision or mastectomy followed by adjuvant radiation therapy. Another method is to shrink the tumor with neoadjuvant chemotherapy prior to radical radiation therapy. A third technique is to enhance the radiosensitivity of the cancer by giving certain drugs during a course of radiation therapy. Examples of radiosensitizing drugs include cisplatin, nimorazole, and cetuximab.
The impact of radiotherapy varies between different types of cancer and different groups. For example, for breast cancer after breast-conserving surgery, radiotherapy has been found to halve the rate at which the disease recurs. In pancreatic cancer, radiotherapy has increased survival times for inoperable tumors. | 0 | Theoretical and Fundamental Chemistry |
Calcium looping technology offers several technical advantages over amine scrubbing for carbon capture. Firstly, both carbonator and calciner can use fluidized bed technology, due to the good gas-solid contacting and uniform bed temperature. Fluidized bed technology has already been demonstrated at large scale: large (460MWe) atmospheric and pressurized systems exist, and there is not a need for intensive scaling up as there is for the solvent scrubbing towers used in amine scrubbing.
Also, the calcium looping process is energy efficient. The heat required for the endothermic calcination of CaCO and the heat required to raise the temperature of fresh limestone from ambient temperature, can be provided by in-situ oxy-fired combustion of fuel in the calciner. Although additional energy is required to separate O from N, the majority of the energy input can be recovered because the carbonator reaction is exothermic and CO from the calciner can be used to power a steam cycle. A solid purge heat exchanger can also be utilized to recover energy from the deactivated CaO and coal ashes from the calciner. As a result, a relatively small efficiency penalty is imposed on the power process, where the efficiency penalty refers to the power losses for CO compression, air separation and steam generation. It is estimated at 6-8 % points, compared to 9.5-12.5 % from post combustion amine capture.
The main shortcoming of Ca-looping technology is the decreased reactivity of CaO through multiple calcination-carbonation cycles. This can be attributed to sintering and the permanent closure of small pores during carbonation. | 1 | Applied and Interdisciplinary Chemistry |
Interchange pathways apply to substitution reactions where intermediates are not observed, which is more common than pure dissociative pathways. If the reaction rate is insensitive to the nature of the attacking nucleophile, the process is called dissociative interchange, abbreviated I. An illustrative process comes from the "anation" (reaction with an anion) of cobalt(III) complexes: | 0 | Theoretical and Fundamental Chemistry |
Photodynamic detection is the use of photosensitive drugs with a light source of the right wavelength for the detection of cancer, using fluorescence of the drug. 5ALA, or derivatives thereof, can be used to visualize bladder cancer by fluorescence imaging. | 1 | Applied and Interdisciplinary Chemistry |
The viscosity of gases is the result in the transfer of each molecule of gas as they pass each other from layer to layer. As gases tend to pass one another, the velocity, in the form of momentum, of the faster moving molecule speeds up the slower moving molecule. As the slower moving molecule passes the faster moving molecule, the momentum of the slower moving particle slows down the faster moving particle. The molecules continue to enact until frictional drag causes both molecules to equalize their velocities. | 1 | Applied and Interdisciplinary Chemistry |
The diverse functions of peroxisomes require dynamic interactions and cooperation with many organelles involved in cellular lipid metabolism such as the endoplasmic reticulum, mitochondria, lipid droplets, and lysosomes.
Peroxisomes interact with mitochondria in several metabolic pathways, including β-oxidation of fatty acids and the metabolism of reactive oxygen species. Both organelles are in close contact with the endoplasmic reticulum and share several proteins, including organelle fission factors. Peroxisomes also interact with the endoplasmic reticulum and cooperate in the synthesis of ether lipids (plasmalogens), which are important for nerve cells (see above). In filamentous fungi, peroxisomes move on microtubules by hitchhiking, a process involving contact with rapidly moving early endosomes. Physical contact between organelles is often mediated by membrane contact sites, where membranes of two organelles are physically tethered to enable rapid transfer of small molecules, enable organelle communication and are crucial for coordination of cellular functions and hence human health. Alterations of membrane contacts have been observed in various diseases. | 1 | Applied and Interdisciplinary Chemistry |
A solution of the amide (0.365 g, 0.809 mmol), Pd(PPh) (0.187 g, 0.162 mmol), and triethylamine (1.12 mL, 8.08 mmol) in MeCN (8 mL) in a sealed tube was heated slowly to 120°. After stirring for 4 hours, the reaction mixture was cooled to room temperature, and the solvent was evaporated. The residue was chromatographed (loaded with CHCl) to give the title product 316 (0.270 g, 90%) as a colorless oil; R 0.42 (EtOAc/petroleum ether 10:1); [α] +14.9 (c, 1.0, CHCl); IR 3027, 2930, 1712, 1673, 1608, 1492, 1343, 1248 cm; H NMR (400 MHz) δ 7.33–7.21 (m, 6 H), 7.07 (dd, J = 7.3, 16.4 Hz, 1 H), 7.00 (t, J = 7.5 Hz, 1 H), 6.77 (d, J = 7.7 Hz, 1 H), 6.30 (dd, J = 8.7, 11.4 Hz, 1 H), 5.32 (d, J = 15.7 Hz, 1 H), 5.04 (s, 1 H), 4.95 (s, 1 H), 4.93 (d, J = 11.1 Hz, 1 H), 4.17 (s, 1 H), 3.98 (d, J = 15.7 Hz, 1 H), 3.62 (d, J = 8.7 Hz, 1 H), 3.17 (s, 3 H), 2.56 (dd, J = 3.5, 15.5 Hz, 1 H), 2.06 (dd, J = 2.8, 15.5 Hz, 1 H); C NMR (100 MHz) δ 177.4, 172.9, 147.8, 142.2, 136.5, 132.2, 131.6, 128.8, 128.4, 128.2, 127.7, 127.1, 123.7, 122.9, 107.9, 105.9, 61.0, 54.7, 49.9, 44.4, 38.2, 26.4; HRMS Calcd. for CHNO: 370.1681. Found: 370.1692. | 0 | Theoretical and Fundamental Chemistry |
Nitric acid has been used in various forms as the oxidizer in liquid-fueled rockets. These forms include red fuming nitric acid, white fuming nitric acid, mixtures with sulfuric acid, and these forms with HF inhibitor. IRFNA (inhibited red fuming nitric acid) was one of three liquid fuel components for the BOMARC missile. | 0 | Theoretical and Fundamental Chemistry |
Hydrogen is a chemical element with an atomic number of 1. It has just one proton and one electron. Deuterium is the heavier naturally occurring, non-radioactive, stable isotope of hydrogen. Deuterium was discovered by Harold Urey in 1931, for which he received the Nobel Prize in 1934. The deuterium isotope effect has become an important tool in the elucidation of the mechanism of chemical reactions. Deuterium contains one proton, one electron, and a neutron, effectively doubling the mass of the deuterium isotope without changing its properties significantly. However, the C–D bond is a bit shorter, and it has reduced electronic polarizability and less hyperconjugative stabilization of adjacent bonds, including developing an anti-bonding orbital as part of the newly formed bond. This can potentially result in weaker van der Waals stabilization, and can produce other changes in properties that are difficult to predict, including changes in the intramolecular volume and the transition state volume. Substituting deuterium for hydrogen yields deuterated compounds that are similar in size and shape to hydrogen-based compounds. | 1 | Applied and Interdisciplinary Chemistry |
Thorin (also called thoron or thoronol) is an indicator used in the determination of barium, beryllium, lithium, uranium and thorium compounds. Being a compound of arsenic, it is highly toxic. | 0 | Theoretical and Fundamental Chemistry |
Polyurea and polyurethane are copolymers used in the manufacture of spandex, which was invented in 1959.
Polyurea was originally developed in automotive applications in the 1980s but other applications such as protecting tabletop edges followed. Its fast reactivity and relative moisture insensitivity made it useful for coatings on large surface area projects, such as secondary containment, manhole and tunnel coatings, tank liners, and truck bed liners. Excellent adhesion to concrete and steel is obtained with the proper primer and surface treatment. They can also be used for spray molding and armor. Some polyureas reach strengths of 40 MPa (6000 psi) tensile and over 500% elongation making it a tough coating. The quick cure time allows many coats to be built up quickly. The high strength and high impact resistance of polyurea coatings is a key reason for their use.
In 2014, a polyurea elastomer-based material was shown to be self-healing, melding together after being cut in half. The material also includes inexpensive commercially available compounds. The elastomer molecules were tweaked, making the bonds between them longer. The resulting molecules are easier to pull apart from one another and better able to rebond at room temperature with almost the same strength. The rebonding can be repeated. Elastic, self-healing paints and other coatings recently took a step closer to common use, thanks to research being conducted at the University of Illinois. Scientists there have used "off-the-shelf" components to create a polymer that melds back together after being cut in half, without the addition of other chemicals.
Polyurea has become a preferred long term solution for narrowboats. The traditional coating with bitumen, known as "blacking" is being replaced with the practice of polyurea coatings. The clearest advantage is that it is not necessary to reapply a coat every 3–4 years. It is thought that polyurea coatings last 25–30 years.
Commercial trademarks for Polyurea include Line-X, GLS 100R, and Pentens SPU-1000, to name a few. There are multiple possible polyurea formulations. The Polyurea Development Association is a trade association that represents the interests of polyurea coating manufacturers. | 0 | Theoretical and Fundamental Chemistry |
Placer mining, the mining of stream beds for minerals, was common practice in the area since the mid nineteenth century.
The Mount Polley ore deposit was discovered subsequent to an airborne magnetometer study completed by the Canadian government in 1964 which detected a significant reading for the surveyed map in the region of Polley Mountain. Investigating further, Karl Springer discovered an alkalic porphyry deposit there the same year.
Quintana Resources prospected the area in 1976, discovering numerous copper float boulders but let their claim to the property lapse in 1978. In 1980, E&B Exploration optioned the property from Highland Crow, a subsidiary of Teck. Through the early 1980s, the potential for gold mining on the site was explored due to the rising global price of the commodity.
The first feasibility study for the site was completed in 1991 and the first permits for developing the deposit were approved the same year. Financing from Imperial Metals however was not yet in place. | 1 | Applied and Interdisciplinary Chemistry |
In about 50 BCE, the Roman philosopher Lucretius proposed that apparently static macroscopic bodies were composed on a small scale of rapidly moving atoms all bouncing off each other. This Epicurean atomistic point of view was rarely considered in the subsequent centuries, when Aristotlean ideas were dominant.
In 1738 Daniel Bernoulli published Hydrodynamica, which laid the basis for the kinetic theory of gases. In this work, Bernoulli posited the argument, that gases consist of great numbers of molecules moving in all directions, that their impact on a surface causes the pressure of the gas, and that their average kinetic energy determines the temperature of the gas. The theory was not immediately accepted, in part because conservation of energy had not yet been established, and it was not obvious to physicists how the collisions between molecules could be perfectly elastic.
Other pioneers of the kinetic theory, whose work was also largely neglected by their contemporaries, were Mikhail Lomonosov (1747), Georges-Louis Le Sage (ca. 1780, published 1818), John Herapath (1816) and John James Waterston (1843), which connected their research with the development of mechanical explanations of gravitation. In 1856 August Krönig created a simple gas-kinetic model, which only considered the translational motion of the particles.
In 1857 Rudolf Clausius developed a similar, but more sophisticated version of the theory, which included translational and, contrary to Krönig, also rotational and vibrational molecular motions. In this same work he introduced the concept of mean free path of a particle. In 1859, after reading a paper about the diffusion of molecules by Clausius, Scottish physicist James Clerk Maxwell formulated the Maxwell distribution of molecular velocities, which gave the proportion of molecules having a certain velocity in a specific range. This was the first-ever statistical law in physics. Maxwell also gave the first mechanical argument that molecular collisions entail an equalization of temperatures and hence a tendency towards equilibrium. In his 1873 thirteen page article Molecules, Maxwell states: "we are told that an atom is a material point, invested and surrounded by potential forces and that when flying molecules strike against a solid body in constant succession it causes what is called pressure of air and other gases."
In 1871, Ludwig Boltzmann generalized Maxwell's achievement and formulated the Maxwell–Boltzmann distribution. The logarithmic connection between entropy and probability was also first stated by Boltzmann.
At the beginning of the 20th century, atoms were considered by many physicists to be purely hypothetical constructs, rather than real objects. An important turning point was Albert Einsteins (1905) and Marian Smoluchowskis (1906) papers on Brownian motion, which succeeded in making certain accurate quantitative predictions based on the kinetic theory.
Following the development of the Boltzmann equation, a framework for its use in developing transport equations was developed independently by David Enskog and Sydney Chapman in 1917 and 1916. The framework provided a route to prediction of the transport properties of dilute gases, and became known as Chapman–Enskog theory. The framework was gradually expanded throughout the following century, eventually becoming a route to prediction of transport properties in real, dense gases. | 0 | Theoretical and Fundamental Chemistry |
The 2013 ILCOR and 2010 American Heart Association guidelines support the use of cooling following resuscitation from cardiac arrest. These recommendations were largely based on two trials from 2002 which showed improved survival and brain function when cooled to after cardiac arrest.
However, more recent research suggests that there is no benefit to cooling to when compared with less aggressive cooling only to a near-normal temperature of ; it appears cooling is effective because it prevents fever, a common complication seen after cardiac arrest. There is no difference in long term quality of life following mild compared to more severe cooling.
In children, following cardiac arrest, cooling does not appear useful as of 2018. | 1 | Applied and Interdisciplinary Chemistry |
Since diffusion and transport of free ammonia across the cell membrane will affect the pH level of the cell, the more attractive and regulated way of transporting ammonia between the neuronal and the astrocytic compartment is via an amino-acid shuttle, of which there are two: leucine and alanine. The amino acid moves in the opposite direction of glutamine. In the opposite direction of the amino acid, a corresponding molecule is transported; for alanine this molecule is lactate; for leucine, α-ketoisocaproate. | 1 | Applied and Interdisciplinary Chemistry |
Many esters have distinctive fruit-like odors, and many occur naturally in the essential oils of plants. This has also led to their common use in artificial flavorings and fragrances which aim to mimic those odors. | 0 | Theoretical and Fundamental Chemistry |
The ability for a mechanical bond to reduce reactivity and hence prevent unwanted reactions has been exploited in a number of areas. One of the earliest applications was in the protection of organic dyes from environmental degradation. | 0 | Theoretical and Fundamental Chemistry |
John French (1616–1657) was an English physician known for his contributions to chemistry (in particular, distillation) as well as for his English translations of Latin and German works. | 1 | Applied and Interdisciplinary Chemistry |
Although no heterotrophs use carbon dioxide in biosynthesis, some carbon dioxide is incorporated in their metabolism. Notably pyruvate carboxylase consumes carbon dioxide (as bicarbonate ions) as part of gluconeogenesis, and carbon dioxide is consumed in various anaplerotic reactions.
6-phosphogluconate dehydrogenase catalyzes the reductive carboxylation of ribulose 5-phosphate to 6-phosphogluconate in E. coli under elevated CO concentrations. | 0 | Theoretical and Fundamental Chemistry |
Mathews married Ella Gillfillan (B.A. 1907, University of Wisconsin) on June 26, 1909. They had two children: Marian and Jean. Marian married M. H. Withey of Madison. Jean married Charles C. Watson, a collaborator with her father and with John Warren Williams in establishing the colloid chemistry research group at the University of Wisconsin. | 0 | Theoretical and Fundamental Chemistry |
In 1971, just after what a later study would identify as the point when the lakes eutrophication began in earnest, M.C. Healey and W.L. Woodall, two researchers from the Fisheries Research Board of Canada, considered Frame in a limnological study of seven lakes in and around Yellowknife that their agency was considering as sites for an experimental fishery. Among the others studied were the larger Kam Lake to the south, and five others outside city limits. Their analysis, published in 1973, showed that while Frames water quality was still good enough to support the recreational use that was still occurring, there were already some signs of decline.
Chemical analysis of the water showed similarities to Kam Lake. Like the larger lake, it had a notably alkaline pH of 8.5, reflecting higher concentrations of salts, and a specific conductance of 332, well below Kam but around three times the values obtained for the other four lakes. Its calcium, magnesium, potassium, and sodium levels were higher than any other lake except Kam, and it had the highest bicarbonate levels at 132.4 mg/L. The lake was found to be generally isothermal, although its depths cooled significantly in August, when the later of two samples was taken. Plenty of oxygen was still in the water. The researchers attributed Frames high biochemical oxygen demand and "peculiar chemical characteristics" to not only the proximity of downtown but the citys use of the lake as a dump for plowed snow.
"Frame Lake had the most peculiar species assemblage for the region", the two wrote of the results of their zooplankton findings. Daphnia middendoffiana, the only Cladocera species found in Frame, was present in only that lake of the seven. Likewise, several copepods—Heterecope sententrionalis and Diaptomus pribilofensis and leptopus—were unique to Frame. Cyclops vernalis was the only species the lake shared with any of the others. "The species in Frame Lake are typical of a lake west of the continental divide, in Alaska or northern British Columbia, but extremely uncommon east of the divide", they observed.
Benthos species in Frame were more similar to the other lakes. Frame shared with the other lakes a high mollusk population, predominantly in the Sphaeriidae and Valvatidae families. Lymnaeidae were unique to it, however. Insect populations around the lake are dominated by non-biting midges, especially the Chironominae and Tanypodinae subfamilies. Healey and Woodall also found significant populations of mayflies, damselflies, and water boatmen in the lake.
They did not find any fish, the only one of the seven lakes where this was the case. Frame nevertheless recorded the highest biomass count of the seven lakes, 7.32 grams of dry weight per square meter of bed, more than three times the second highest reading, on the second of two sampling periods in summer 1971. At the same time, that biomass had the lowest ash content of any of the sampled lakes as well. | 1 | Applied and Interdisciplinary Chemistry |
* left hand side of Navier–Stokes equations minus body force (per unit volume) acting on fluid.
* this relation is derived using this relationship which is alternative form of continuity equation | 0 | Theoretical and Fundamental Chemistry |
In fluid mechanics, the pressure-gradient force is the force that results when there is a difference in pressure across a surface. In general, a pressure is a force per unit area across a surface. A difference in pressure across a surface then implies a difference in force, which can result in an acceleration according to Newtons second law of motion, if there is no additional force to balance it. The resulting force is always directed from the region of higher-pressure to the region of lower-pressure. When a fluid is in an equilibrium state (i.e. there are no net forces, and no acceleration), the system is referred to as being in hydrostatic equilibrium. In the case of atmospheres, the pressure-gradient force is balanced by the gravitational force, maintaining hydrostatic equilibrium. In Earths atmosphere, for example, air pressure decreases at altitudes above Earth's surface, thus providing a pressure-gradient force which counteracts the force of gravity on the atmosphere. | 1 | Applied and Interdisciplinary Chemistry |
Praseodymium(III) nitride forms black crystals of a cubic system. The space group is Fm3m, with cell parameter a = 0.5165 nm, Z = 4, its structure similar to that of sodium chloride (NaCl).
The compound is readily hydrolyzed with water and reacts with acids. | 0 | Theoretical and Fundamental Chemistry |
The word environmental has its root in the late 19th-century French word environ (verb), meaning to encircle or to encompass. The word environment was used by Carlyle in 1827 to refer to the aggregate of conditions in which a person or thing lives. The meaning shifted again in 1956 when it was used in the ecological sense, where Ecology is the branch of science dealing with the relationship of living things to their environment.
The second part of the phrase environmental engineer originates from Latin roots and was used in the 14th century French as engignour, meaning a constructor of military engines such as trebuchets, harquebuses, longbows, cannons, catapults, ballistas, stirrups, armour as well as other deadly or bellicose contraptions. The word engineer was not used to reference public works until the 16th century; and it likely entered the popular vernacular as meaning a contriver of public works during John Smeaton's time. | 1 | Applied and Interdisciplinary Chemistry |
Cantilever enhanced photoacoustics measuring technology can be used e.g. in detection and analysis of gases, liquids, and solid materials in applications of research, industry, environmental, safety, and security. | 0 | Theoretical and Fundamental Chemistry |
Kai Simons is the son of a physics professor. His father convinced him to study medicine, though he originally wanted to study physics. While studying at the University of Helsinki, Simons spent a summer internship in the Stockholm laboratory of Bengt Samuelsson There, he studied mechanisms of vitamin B12 absorption. He worked with other students to organize a campaign to fight taeniasis, a disease common in eastern Finland where eating raw fish is popular.
After completing his MD in 1964, he began a postdoctoral fellowship at Rockefeller University in New York City where he worked between 1966 and 1967 on blood serum protein polymorphism. He returned to Helsinki in 1967, where he began working as a Junior Investigator for the Finnish Medical Research Council at the University of Helsinki. He became a group leader in 1972 and was a biochemistry professor in 1971–79 at the medical faculty of this university At first, he continued his work on serum proteins. Next, together with Leevi Kääriäinen and Ossi Renkonen, he started a research team – later joined by Ari Helenius, his first PhD student and later a post doctoral researcher who became Simons' brother-in-law. After a one-month stay in MRC Laboratory for Molecular Biology in Cambridge, the group started investigating a Semliki Forest virus, introduced to Simons by Kääriäinen.
In 1975 Simons came to Heidelberg (Germany), as one of the EMBL group leaders. Together with Ari Helenius he helped to develop EMBL, headed at this time by John Kendrew. In years 1982–1998 Simons was a coordinator of the Cell Biology Program there. During this time he for the first time presented the concept of lipid rafts.
In 1999 he took part in setting up ELSO (later incorporated into EMBO), which later he presided over.
He was one of the initiators of establishing and building Max Planck Institute of Molecular Cell Biology and Genetics in Dresden (Germany), where he moved. Formally from 1998 (beginning of MPI-CBG construction) and practically from 2000 he was one of five institutes directors and also a group leader there Since 2006 he is a director emeritus'.
In 2012 he started-up a biotech company Lipotype GmbH, where he is a CEO.
He is married to Carola Simons and a father of three: twins – Mikael (neurobiologist) and Katja (sociologist), and the youngest of three, Matias (physician). | 1 | Applied and Interdisciplinary Chemistry |
*Bio: Shortened form of Biology; refers to usage of bacteria.
*Hydro: Term referring to the usage of water; process occurs in aqueous environments
*Metallurgy: A process involving the separating and refining of metals from other substances;
*Bioleaching: Using biological agents (bacteria) to extract metals or soils; general term used to encompass all forms biotechnological forms of extraction (hydrometallurgy, biohydrometallurgy, biomining, etc) | 1 | Applied and Interdisciplinary Chemistry |
It is possible to perform lateral force measurements using a nc-AFM probe oscillating normal to the surface under study. This method uses a similar method to force spectroscopy except the tip is moved parallel to the surface while the frequency shift is recorded, this is repeated at multiple heights above the surface, starting far from the surface and moving closer. After any change to the surface, for example moving an atom on the surface, the experiment is stopped. This leaves a 2D grid of measured frequency shifts. Using an appropriate force spectroscopy calculation each of the vertical frequency shift vectors can be converted into a vector of forces in the z-direction, thus creating a 2D grid of calculated forces. These forces can be integrated vertically to produce a 2D map of the potential. It is then possible to differentiate the potential horizontally to calculate the lateral forces. As this method relies on heavy mathematical processing, in which each state assumes a vertical motion of the tip, it is critical that the sensor is not angled, and that the tip length is very short compared to the length of the sensor.
A direct measurement of lateral forces is possible by using a torsional mode with a silicon cantilever or by orienting the sensor to oscillate parallel to the surface. Using the latter technique, Weymouth et al. measured the tiny interaction of two CO molecules as well as the lateral stiffness of a CO terminated tip. | 0 | Theoretical and Fundamental Chemistry |
Emerging technologies are aiming to combine pooled CRISPR screens with the detailed resolution of massively parallel single-cell RNA-sequencing (RNA-seq). Studies utilising “CRISP-seq”, “CROP-seq”, and “PERTURB-seq” have demonstrated rich genomic readouts, accurately identifying gene expression signatures for individual gene knockouts in a complex pool of cells. These methods have the added benefit of producing transcriptional profiles of the sgRNA-induced cells. | 1 | Applied and Interdisciplinary Chemistry |
It is often useful to group processes into pairs, in which each variable held constant is one member of a conjugate pair. | 0 | Theoretical and Fundamental Chemistry |
Depletion forces were first described by Sho Asakura and Fumio Oosawa in 1954. In their model, the force is always considered to be attractive. Additionally, the force is considered to be proportional to the osmotic pressure. The Asakura–Oosawa model assumes low macromolecule densities and that the density distribution, , of the macromolecules is constant. Asakura and Oosawa described four cases in which depletion forces would occur. They first described the most general case as two solid plates in a solution of macromolecules. The principles for the first case were then extended to three additional cases. | 0 | Theoretical and Fundamental Chemistry |
Before signals can be detected in a ZULF NMR experiment, it is first necessary to polarize the nuclear spin ensemble, since the signal is proportional to the nuclear spin magnetization. There are a number of methods to generate nuclear spin polarization. The most common is to allow the spins to thermally equilibrate in a magnetic field, and the nuclear spin alignment with the magnetic field due to the Zeeman interaction leads to weak spin polarization. The polarization generated in this way is on the order of 10 for tesla field-strengths.
An alternative approach is to use hyperpolarization techniques, which are chemical and physical methods to generate nuclear spin polarization. Examples include parahydrogen-induced polarization, spin-exchange optical pumping of noble gas atoms, dissolution dynamic nuclear polarization, and chemically-induced dynamic nuclear polarization. | 0 | Theoretical and Fundamental Chemistry |
Steel casing pipe, also known as encasement pipe, is most commonly used in underground construction to protect utility lines of various types from getting damaged. Such damage might occur due to the elements of nature or human activity.
Steel casing pipe is used in different types of horizontal underground boring, where the pipe is jacked into an augered hole in segments and then connected together by welding or by threaded and coupled ends, or other proprietary pipe connectors such as interference-fit interlocking push-on joints. The steel casing pipe can also be set up and welded into a "ribbon" and then directionally pulled through a previously drilled hole under highways, railroads, lakes and rivers. | 1 | Applied and Interdisciplinary Chemistry |
Using experimental data as a starting point, homology transfer is one way to predict interactomes. Here, PPIs from one organism are used to predict interactions among homologous proteins in another organism ("interologs"). However, this approach has certain limitations, primarily because the source data may not be reliable (e.g. contain false positives and false negatives). In addition, proteins and their interactions change during evolution and thus may have been lost or gained. Nevertheless, numerous interactomes have been predicted, e.g. that of Bacillus licheniformis.
Some algorithms use experimental evidence on structural complexes, the atomic details of binding interfaces and produce detailed atomic models of protein–protein complexes as well as other protein–molecule interactions. Other algorithms use only sequence information, thereby creating unbiased complete networks of interaction with many mistakes.
Some methods use machine learning to distinguish how interacting protein pairs differ from non-interacting protein pairs in terms of pairwise features such as cellular colocalization, gene co-expression, how closely located on a DNA are the genes that encode the two proteins, and so on. Random Forest has been found to be most-effective machine learning method for protein interaction prediction. Such methods have been applied for discovering protein interactions on human interactome, specifically the interactome of Membrane proteins and the interactome of Schizophrenia-associated proteins. | 1 | Applied and Interdisciplinary Chemistry |
A pigment termed molybdenum blue is recorded in 1844 as a mixture of molybdenum with "oxyde of tin or phosphate of lime". An alternative formulation involves "digesting" molybdenum sulfide with nitric acid to form molybdic acid, which is then mixed with tin filings and a little muriatic acid (HCl). This is evaporated and heated with alumina. A 1955 paper states that molybdenum blue is unstable and is not used commercially as a pigment. The chemistry of these pigments has not been investigated. | 0 | Theoretical and Fundamental Chemistry |
The 1st analytical group of cations consists of ions which form insoluble chlorides. As such, the group reagent to separate them is hydrochloric acid, usually used at a concentration of 1–2 M. Concentrated HCl must not be used, because it forms a soluble complex ([PbCl]) with Pb. Consequently, the Pb ion would go undetected.
The most important cations in the 1st group are Ag, Hg, and Pb. The chlorides of these elements cannot be distinguished from each other by their colour - they are all white solid compounds. PbCl is soluble in hot water, and can therefore be differentiated easily. Ammonia is used as a reagent to distinguish between the other two. While AgCl dissolves in ammonia (due to the formation of the complex ion [Ag(NH)]), HgCl gives a black precipitate consisting of a mixture of chloro-mercuric amide and elemental mercury. Furthermore, AgCl is reduced to silver under light, which gives samples a violet colour.
PbCl is far more soluble than the chlorides of the other two ions, especially in hot water. Therefore, HCl in concentrations which completely precipitate Hg and Ag may not be sufficient to do the same to Pb. Higher concentrations of Cl cannot be used for the before mentioned reasons. Thus, a filtrate obtained after first group analysis of Pb contains an appreciable concentration of this cation, enough to give the test of the second group, viz. formation of an insoluble sulfide. For this reason, Pb is usually also included in the 2nd analytical group.
This group can be determined by adding the salt in water and then adding dilute hydrochloric acid. A white precipitate is formed, to which ammonia is then added. If the precipitate is insoluble, then Pb is present; if the precipitate is soluble, then Ag is present, and if the white precipitate turns black, then Hg is present.
Confirmation test for Pb:
:Pb + 2 KI → PbI + 2 K
:Pb + KCrO → PbCrO + 2 K
Confirmation test for Ag:
:Ag + KI → AgI + K
:2Ag + KCrO → AgCrO + 2 K
Confirmation test for Hg:
:Hg + 2 KI → HgI + 2 K
:2 Hg + 2 NaOH → 2 HgO + 2 Na + HO | 0 | Theoretical and Fundamental Chemistry |
According to historian Tonio Andrade, "Scholars today overwhelmingly concur that the gun was invented in China," however multiple independent gunpowder and gun invention theories continue to exist today, advocating for European, Islamic, or Indian origins. Opponents of Chinese invention and transmission criticize the vagueness of Chinese records on specific gunpowder usage in weaponry, the possible lack of gunpowder in incendiary weapons as described by Chinese documents, the weakness of Chinese firearms, the lack of evidence of guns between Europe and China before 1326, and emphasize the appearance of earlier or superior gunpowder weapons. For example, Stephen Morillo, Jeremy Black, and Paul Lococos War in World History argues that "the sources are not entirely clear about Chinese use of gunpowder in guns. There are references to bamboo and iron cannons, or perhaps proto-cannons, but these seem to have been small, unreliable, handheld weapons in this period. The Chinese do seem to have invented guns independently of the Europeans, at least in principle; but, in terms of effective cannon, the edge goes to Europe." Independent invention theories include examples such as the attribution of gunpowder to Berthold Schwarz (Black Berthold), the usage of cannons by Mamluks at the Battle of Ain Jalut in 1260, and descriptions of gunpowder and firearms to various Sanskrit texts. The problem with all theories of non-Chinese invention boils down to lack of evidence and dating. Its not certain who exactly Berthold Schwarz was since there are no contemporary records of him. According to J.R. Partington, Black Berthold is a purely legendary figure invented for the purpose of providing a German origin for gunpowder and cannon. The source for Mamluk usage of cannons in the Battle of Ain Jalut is a text dated to the late 14th century. The dating of the cited Sanskrit texts is often dubious at best, with one example, Sukraniti, containing descriptions of a musket and a cart-drawn gun.
Proponents of Chinese invention and transmission point out the acute dearth of any significant evidence of evolution or experimentation with gunpowder or gunpowder weapons leading up to the gun outside of China. Gunpowder appeared in Europe primed for military usage as an explosive and propellant, bypassing a process which took centuries of Chinese experimentation with gunpowder weaponry to reach, making a nearly instantaneous and seamless transition into firearm warfare, as its name suggests. Furthermore, early European gunpowder recipes shared identical defects with Chinese recipes such as the inclusion of the poisons sal ammoniac and arsenic, which provide no benefit to gunpowder. Bert S. Hall explains this phenomenon in his Weapons and Warfare in Renaissance Europe: Gunpowder, Technology, and Tactics by drawing upon the gunpowder transmission theory, explaining that "gunpowder came [to Europe], not as an ancient mystery, but as a well-developed modern technology, in a manner very much like twentieth-century technology-transfer projects." In a similar vein, Peter Lorge supposes that the Europeans experienced gunpowder "free from preconceived notions of what could be done," in contrast to China, "where a wide range of formulas and a broad variety of weapons demonstrated the full range of possibilities and limitations of the technologies involved." There is also the vestige of Chinese influence on Muslim terminology of key gunpowder related items such as saltpeter, which has been described as either Chinese snow or salt, fireworks which were called Chinese flowers, and rockets which were called Chinese arrows. Moreover, Europeans in particular experienced great difficulty in obtaining saltpeter, a primary ingredient of gunpowder which was relatively scarce in Europe compared to China, and had to be obtained from "distant lands or extracted at high cost from soil rich in dung and urine." Thomas Arnold believes that the similarities between early European cannons and contemporary Chinese models suggests a direct transmission of cannon making knowledge from China rather than a home grown development. | 1 | Applied and Interdisciplinary Chemistry |
Recombinase polymerase amplification (RPA) is a single tube, isothermal alternative to the polymerase chain reaction (PCR). By adding a reverse transcriptase enzyme to an RPA reaction it can detect RNA as well as DNA, without the need for a separate step to produce cDNA,. Because it is isothermal, RPA can use much simpler equipment than PCR, which requires a thermal cycler. Operating best at temperatures of 37–42 °C and still working, albeit more slowly, at room temperature means RPA reactions can in theory be run quickly simply by holding a tube. This makes RPA an excellent candidate for developing low-cost, rapid, point-of-care molecular tests. An international quality assessment of molecular detection of Rift Valley fever virus performed as well as the best RT-PCR tests, detecting less concentrated samples missed by some PCR tests and an RT-LAMP test.
RPA was developed and launched by TwistDx Ltd. (formerly known as ASM Scientific Ltd), a biotechnology company based in Cambridge, UK. | 1 | Applied and Interdisciplinary Chemistry |
Ilya Iosifovich Moiseev (; 15 March 1929 – 10 October 2020) was a Soviet and Russian chemist. An expert in both kinetics and the coordination chemistry of transition metals, he made significant advances in metal-complex catalysis. | 0 | Theoretical and Fundamental Chemistry |
Hermann Senftleben (April 8, 1890, in Bremen – 1975 in Recklinghausen) was a German physicist and physical chemist. | 0 | Theoretical and Fundamental Chemistry |
Recreation of the prostate epithelium is motivated by evidence suggesting it to be the site of nucleation in cancer metastasis. These systems essentially serve as the next step in the development of cells cultured from mice to two and subsequently three-dimensional human cell culturing. PDMS developments have enabled the creation of microfluidic systems that offer the benefit of adjustable topography, gas and liquid exchange, as well as an ease of observation via conventional microscopy.
Researchers at the University of Grenoble Alpes have outlined a methodology that utilizes such a microfluidic system in the attempt to construct a viable Prostate epithelium model. The approach focuses on a cylindrical microchannel configuration, mimicking the morphology of a human secretory duct, within which the epithelium is located. Various microchannel diameters were assessed for successful promotion of cell cultures, and it was observed that diameters of 150-400 µm were the most successful. Furthermore, cellular adhesion endured throughout this experimentation, despite the introduction of physical stress through variations in microfluidic currents.
The objective of these constructions is to facilitate the collection of prostatic fluid, along with gauging cellular reactions to microenvironmental changes. Additionally, prostate-on-a-chip enables the recreation of metastasis scenarios, which allows the assessment of drug candidates and other therapeutic approaches. Scalability of this method is also attractive to researchers, as the reusable mold approach ensures a low-cost of production. | 1 | Applied and Interdisciplinary Chemistry |
From 1942 to 1945, Cram worked in chemical research at Merck & Co laboratories, doing penicillin research with mentor Max Tishler. Postdoctoral work was as an American Chemical Society postdoctoral fellow at the Massachusetts Institute of Technology, with John D. Roberts. Cram was the originator of Cram's rule, which provides a model for predicting the outcome of nucleophilic attack of carbonyl compounds. He published over 350 research papers and eight books on organic chemistry, and taught graduate and post-doctoral students from 21 different countries. | 0 | Theoretical and Fundamental Chemistry |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.