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Rubber expansion joints are mainly manufactured by manual wrapping of rubber sheets and fabric reinforced rubber sheets around a bellows-shaped product mandrel. Besides rubber and fabric, reinforced rubber and/or steel wires or metal rings are added for additional reinforcement. After the entire product is built up on the mandrel, it is covered with a winding of (nylon) peel ply to pressurize all layers together. Because of the labor-intensive production process, a large part of the production has moved to eastern Europe and Asian countries. | 1 | Applied and Interdisciplinary Chemistry |
PET scanning is non-invasive, but it does involve exposure to ionizing radiation. FDG, which is now the standard radiotracer used for PET neuroimaging and cancer patient management, has an effective radiation dose of 14 mSv.
The amount of radiation in FDG is similar to the effective dose of spending one year in the American city of Denver, Colorado (12.4 mSv/year). For comparison, radiation dosage for other medical procedures range from 0.02 mSv for a chest X-ray and 6.5–8 mSv for a CT scan of the chest. Average civil aircrews are exposed to 3 mSv/year, and the whole body occupational dose limit for nuclear energy workers in the US is 50 mSv/year. For scale, see Orders of magnitude (radiation).
For PET-CT scanning, the radiation exposure may be substantial—around 23–26 mSv (for a 70 kg person—dose is likely to be higher for higher body weights). | 1 | Applied and Interdisciplinary Chemistry |
In 1667, Johann Joachim Becher published his book , which contained the first instance of what would become the phlogiston theory. In his book, Becher eliminated fire and air from the classical element model and replaced them with three forms of the earth: , , and . was the element that imparted oily, sulphurous, or combustible properties. Becher believed that was a key feature of combustion and was released when combustible substances were burned. Becher did not have much to do with phlogiston theory as we know it now, but he had a large influence on his student Stahl. Bechers main contribution was the start of the theory itself, however much of it was changed after him. Bechers idea was that combustible substances contain an ignitable matter, the . | 1 | Applied and Interdisciplinary Chemistry |
Metal aromaticity or metalloaromaticity is the concept of aromaticity, found in many organic compounds, extended to metals and metal-containing compounds. The first experimental evidence for the existence of aromaticity in metals was found in aluminium cluster compounds of the type where M stands for lithium, sodium or copper. These anions can be generated in a helium gas by laser vaporization of an aluminium / lithium carbonate composite or a copper or sodium / aluminium alloy, separated and selected by mass spectrometry and analyzed by photoelectron spectroscopy. The evidence for aromaticity in these compounds is based on several considerations. Computational chemistry shows that these aluminium clusters consist of a tetranuclear plane and a counterion at the apex of a square pyramid. The unit is perfectly planar and is not perturbed the presence of the counterion or even the presence of two counterions in the neutral compound . In addition its HOMO is calculated to be a doubly occupied delocalized pi system making it obey Hückel's rule. Finally a match exists between the calculated values and the experimental photoelectron values for the energy required to remove the first 4 valence electrons. The first fully metal aromatic compound was a cyclogallane with a Ga core discovered by Gregory Robinson in 1995.
D-orbital aromaticity is found in trinuclear tungsten and molybdenum metal clusters generated by laser vaporization of the pure metals in the presence of oxygen in a helium stream. In these clusters the three metal centers are bridged by oxygen and each metal has two terminal oxygen atoms. The first signal in the photoelectron spectrum corresponds to the removal of the valence electron with the lowest energy in the anion to the neutral compound. This energy turns out to be comparable to that of bulk tungsten trioxide and molybdenum trioxide. The photoelectric signal is also broad which suggests a large difference in conformation between the anion and the neutral species. Computational chemistry shows that the anions and dianions are ideal hexagons with identical metal-to-metal bond lengths. Tritantalum oxide clusters (TaO) also are observed to exhibit possible D-orbital aromaticity.
The molecules discussed thus far only exist diluted in the gas phase. A study exploring the properties of a compound formed in water from sodium molybdate () and iminodiacetic acid also revealed evidence of aromaticity, but this compound has actually been isolated. X-ray crystallography showed that the sodium atoms are arranged in layers of hexagonal clusters akin to pentacenes. The sodium-to-sodium bond lengths are unusually short (327 pm versus 380 pm in elemental sodium) and, like benzene, the ring is planar. In this compound each sodium atom has a distorted octahedral molecular geometry with coordination to molybdenum atoms and water molecules. The experimental evidence is supported by computed NICS aromaticity values. | 0 | Theoretical and Fundamental Chemistry |
Many important metal ores are sulfides. Significant examples include: argentite (silver sulfide), cinnabar (mercury sulfide), galena (lead sulfide), molybdenite (molybdenum sulfide), pentlandite (nickel sulfide), realgar (arsenic sulfide), and stibnite (antimony), sphalerite (zinc sulfide), and pyrite (iron disulfide), and chalcopyrite (iron-copper sulfide). This sulfide minerals recorded information (like isotopes) of their surrounding environment during their formation. Scientists use these minerals to study environments in the deep sea or in the Earth's past. | 0 | Theoretical and Fundamental Chemistry |
As of 2012, these were the twelve member societies of the CEEES:
*Italy: Associazione Italia Tecnici Prove Ambientali (AITPA)
*France: Association pour le Développement des Sciences et Techniques de l'Environnement (ASTE)
*Belgium: Belgian Society of Mechanical and Environmental Engineering (BSMEE)
*Germany: Gesellschaft für Umweltsimulation (GUS)
*Finland: Finnish Society of Environmental Engineering (KOTEL)
*Czech Republic: National Association of Czech Environmental Engineers (NACEI)
*Austria: Österreichische Gesellschaft für Umweltsimulation (ÖGUS)
*Netherlands: PLatform Omgevings Technologie (PLOT)
*United Kingdom: Society of Environmental Engineers (SEE)
*Sweden: Swedish Environmental Engineering Society (SEES)
*Portugal: Sociedade Portuguesa de Simulacao Ambiental e Aveliaca de Riscos (SOPSAR)
*Switzerland: Swiss Society for Environmental Engineering (SSEE)
Each member society successively holds the presidency and the secretariat for a period of two years. | 1 | Applied and Interdisciplinary Chemistry |
The equations, in the absence of gravity, admits an explicit solution, which is called as the N-pole solution since the equation admits a pole decomposition,as shown by Olivier Thual, Uriel Frisch and Michel Hénon in 1988. Consider the 1d equation
where is the Fourier transform of . This has a solution of the form
where (which appear in complex conjugate pairs) are poles in the complex plane. In the case periodic solution with periodicity , the it is sufficient to consider poles whose real parts lie between the interval and . In this case, we have
These poles are interesting because in physical space, they correspond to locations of the cusps forming in the flame front. | 1 | Applied and Interdisciplinary Chemistry |
Ida Noddack was nominated three times for the Nobel Prize in Chemistry due to her discovery of rhenium and masurium. Noddack and her husband were repeatedly nominated for the Nobel Prize in 1932, 1933, 1935 and 1937 (once by Walther Nernst and K. L. Wagner for 1933; both Noddacks were nominated by W. J. Müller for 1935 and by A. Skrabal for 1937). The two of them were also awarded the German Chemical Society's prestigious Liebig Medal in 1931. In 1934, they received the Scheele Medal of the Swedish Chemical Society as well as the German patent for rhenium concentrate.
In 2020 a memorial medal of the discovery was issued by ISTR, designed by Igor Petrov. | 1 | Applied and Interdisciplinary Chemistry |
Galvanic corrosion is the electrochemical erosion of metals. Corrosion occurs when two dissimilar metals are in contact with each other in the presence of an electrolyte, such as salt water. This forms a galvanic cell, with hydrogen gas forming on the more noble (less active) metal. The resulting electrochemical potential then develops an electric current that electrolytically dissolves the less noble material. A concentration cell can be formed if the same metal is exposed to two different concentrations of electrolyte. | 1 | Applied and Interdisciplinary Chemistry |
Antiaromatic compounds, often being very unstable, can be highly reactive in order to relieve the antiaromatic destabilization. Cyclobutadiene, for example, rapidly dimerizes with no potential energy barrier via a 2 + 2 cycloaddition reaction to form tricyclooctadiene. While the antiaromatic character of cyclobutadiene is the subject of debate, the relief of antiaromaticity is usually invoked as the driving force of this reaction.
Antiaromaticity can also have a significant effect on pK. The linear compound propene has a pK of 44, which is relatively acidic for an sp carbon center because the resultant allyl anion can be resonance stabilized. The analogous cyclic system appears to have even more resonance stabilized, as the negative charge can be delocalized across three carbons instead of two. However, the cyclopropenyl anion has 4 π electrons in a cyclic system and in fact has a substantially higher pK than 1-propene because it is antiaromatic and thus destabilized. Because antiaromatic compounds are often short-lived and difficult to work with experimentally, antiaromatic destabilization energy is often modeled by simulation rather than by experimentation.
Some antiaromatic compounds are stable, especially larger cyclic systems (in which the antiaromatic destabilization is not as substantial). For example, the aromatic species 1 can be reduced to 2 with a relatively small penalty for forming an antiaromatic system. The antiaromatic 2 does revert to the aromatic species 1 over time by reacting with oxygen in the air because the aromaticity is preferred.
The loss of antiaromaticity can sometimes be the driving force of a reaction. In the following keto-enol tautomerization, the product enol is more stable than the original ketone even though the ketone contains an aromatic benzene moiety (blue). However, there is also an antiaromatic lactone moiety (green). The relief of antiaromatic destabilization provides a driving force that outweighs even the loss of an aromatic benzene. | 0 | Theoretical and Fundamental Chemistry |
In coastal areas the groundwater and seawater flows are driven by a variety of factors. Both types of water can circulate in marine sediments due to tidal pumping, waves, bottom currents or density driven transport processes. Meteoric freshwaters can discharge along confined and unconfined aquifers into the sea or the oppositional process of seawater intruding into groundwater charged aquifers can take place. The flow of both fresh and sea water is primarily controlled by the hydraulic gradients between land and sea and differences in the densities between both waters and the permeabilities of the sediments.
According to Drabbe and Badon-Ghijben (1888) and Herzberg (1901), the thickness of a freshwater lens below sea level (z) corresponds with the thickness of the freshwater level above sea level (h) as:
z= ρf/((ρs-ρf))*h
With z being the thickness between the saltwater-freshwater interface and the sea level, h being the thickness between the top of the freshwater lens and the sea level, ρf being the density of freshwater and ρs being the density of saltwater. Including the densities of freshwater (ρf = 1.00 g •cm-3) and seawater (ρs = 1.025 g •cm-3) equation (2) simplifies to:
z=40*h
Together with Darcy's Law, the length of a salt wedge from the shoreline into the hinterland can be calculated:
L= ((ρs-ρf)Kf m)/(ρf Q)
With Kf being the hydraulic conductivity, m the aquifer thickness and Q the discharge rate. Assuming an isotropic aquifer system the length of a salt wedge solely depends on the hydraulic conductivity, the aquifer thickness and is inversely related to the discharge rate. These assumptions are only valid under hydrostatic conditions in the aquifer system. In general the interface between fresh and saline water forms a zone of transition due to diffusion/dispersion or local anisotropy. | 0 | Theoretical and Fundamental Chemistry |
In 2019, the discovery of potent, and selective antagonists of the Luteinizing Hormone Receptor (BAY-298 and BAY-899) were reported which were able to reduce sex hormone levels in vivo. The latter fulfils the quality criteria for a Donated Chemical Probe as defined by the Structural Genomics Consortium.
A series of thienopyr(im)idine-based compounds leading to optimized Org 43553 were described as the first Luteinizing Hormone Receptor agonists. | 1 | Applied and Interdisciplinary Chemistry |
Observe that in the special case of a water–silver interface where the contact angle is equal to 90°, the liquid–solid/solid–air surface tension difference is exactly zero.
Another special case is where the contact angle is exactly 180°. Water with specially prepared Teflon approaches this. Contact angle of 180° occurs when the liquid–solid surface tension is exactly equal to the liquid–air surface tension. | 0 | Theoretical and Fundamental Chemistry |
Bed shear stress can be used to find:
* The vertical velocity profile within the fluid flow
* The ability of the fluid to carry sediment
* The rate of shear dispersion of contaminants and tracers. | 1 | Applied and Interdisciplinary Chemistry |
There are four different general schemes in which diffusion may take place. Tracer diffusion and chemical diffusion differ in the level of adsorbate coverage at the surface, while intrinsic diffusion and mass transfer diffusion differ in the nature of the diffusion environment. Tracer diffusion and intrinsic diffusion both refer to systems where adparticles experience a relatively homogeneous environment, whereas in chemical and mass transfer diffusion adparticles are more strongly affected by their surroundings.
*Tracer diffusion describes the motion of individual adparticles on a surface at relatively low coverage levels. At these low levels (< 0.01 monolayer), particle interaction is low and each particle can be considered to move independently of the others. The single atom diffusing in figure 1 is a nice example of tracer diffusion.
*Chemical diffusion describes the process at higher level of coverage where the effects of attraction or repulsion between adatoms becomes important. These interactions serve to alter the mobility of adatoms. In a crude way, figure 3 serves to show how adatoms may interact at higher coverage levels. The adatoms have no "choice" but to move to the right at first, and adjacent adatoms may block adsorption sites from one another.
*Intrinsic diffusion occurs on a uniform surface (e.g. lacking steps or vacancies) such as a single terrace, where no adatom traps or sources are present. This regime is often studied using field ion microscopy, wherein the terrace is a sharp sample tip on which an adparticle diffuses. Even in the case of a clean terrace the process may be influenced by non-uniformity near the edges of the terrace.
*Mass transfer diffusion takes place in the case where adparticle sources and traps such as kinks, steps, and vacancies are present. Instead of being dependent only on the jump potential barrier E, diffusion in this regime is now also dependent on the formation energy of mobile adparticles. The exact nature of the diffusion environment therefore plays a role in dictating the diffusion rate, since the formation energy of an adparticle is different for each type of surface feature as is described in the Terrace Ledge Kink model. | 0 | Theoretical and Fundamental Chemistry |
In immunology, a conformational epitope is a sequence of sub-units (usually amino acids) composing an antigen that come in direct contact with a receptor of the immune system.
An antigen is any substance that the immune system can recognize as foreign. Antigens are usually proteins that are too large to bind as a whole to any receptor so only specific segments, that form the antigen, bind with a specific receptor. Such segments are called epitopes. Likewise, it is only the paratope of the receptor that comes in contact with the epitope.
Proteins are composed of repeating nitrogen-containing subunits called amino acids that in nature do not exist as straight chains but as folded whorls with complex loops. The latter is known as the tertiary structure of a protein. So, whenever a receptor interacts with an undigested antigen, the surface amino acids that come in contact may not be continuous with each other if the protein is unwound. Such discontinuous amino acids that come together in three-dimensional conformation and interact with the receptor's paratope are called conformational epitopes. In contrast, if the antigen is digested, small segments called peptides are formed, which bind with major histocompatibility complex molecules, and then later with T cell receptors through amino acids that are continuous in a line. These are known as linear epitopes. | 1 | Applied and Interdisciplinary Chemistry |
Besides the set of parameters obtained by Pitzer et al. in the 1970s mentioned in the previous section. Kim and Frederick published the Pitzer parameters for 304 single salts in aqueous solutions at 298.15 K, extended the model to the concentration range up to the saturation point. Those parameters are widely used, however, many complex electrolytes including ones with organic anions or cations, which are very significant in some
related fields, were not summarized in their paper.
For some complex electrolytes, Ge et al. obtained the new set of Pitzer parameters using up-to-date measured or critically reviewed osmotic coefficient or activity coefficient data. | 0 | Theoretical and Fundamental Chemistry |
Daily light integral (DLI) describes the number of photosynthetically active photons (individual particles of light in the 400-700 nm range) that are delivered to a specific area over a 24-hour period. This variable is particularly useful to describe the light environment of plants. | 0 | Theoretical and Fundamental Chemistry |
In the thermodynamic stream of thinking, the specified mechanisms of heat transfer are conduction and radiation. These mechanisms presuppose recognition of temperature; empirical temperature is enough for this purpose, though absolute temperature can also serve. In this stream of thinking, quantity of heat is defined primarily through calorimetry.
Though its definition of them differs from that of the mechanical stream of thinking, the empirical stream of thinking nevertheless presupposes the existence of adiabatic enclosures. It defines them through the concepts of heat and temperature. These two concepts are coordinately coherent in the sense that they arise jointly in the description of experiments of transfer of energy as heat. | 0 | Theoretical and Fundamental Chemistry |
Clinical and translational data suggest that sensitive tumor types, with adequate parameters and functional apoptosis pathways, might not need high doses of mTOR inhibitors to trigger apoptosis. In most cases, cancer cells might only be partially sensitive to mTOR inhibitors due to redundant signal transduction or lack of functional apoptosis signaling pathways. In situations like this, high doses of mTOR inhibitors might be required. In a recent study of patients with Renal cell carcinoma, resistance to Temsirolimus was associated with low levels of p-AKT and p-S6K1, that play the key role in mTOR activation. These data strongly suggests number of tumors with an activated PI3K/AKT/mTOR signaling pathway that does not respond to mTOR inhibitors. For future studies, it is recommended to exclude patients with low or negative p-AKT levels from trials with mTOR inhibitors.
Current data is insufficient to predict sensitivity of tumors to rapamycin. However, the existing data allows us to characterize tumors that might not respond to rapalogs. | 1 | Applied and Interdisciplinary Chemistry |
A float switch is a type of level sensor, a device used to detect the level of liquid within a tank. The switch may be used to control a pump, as an indicator, an alarm, or to control other devices.
One type of float switch uses a mercury switch inside a hinged float. Another common type is a float that raises a rod to actuate a microswitch. One pattern uses a reed switch mounted in a tube; a float, containing a magnet, surrounds the tube and is guided by it. When the float raises the magnet to the reed switch, it closes. Several reeds can be mounted in the tube for different level indications by one assembly.
A very common application is in sump pumps and condensate pumps where the switch detects the rising level of liquid in the sump or tank and energizes an electrical pump which then pumps liquid out until the level of the liquid has been substantially reduced, at which point the pump is switched off again. Float switches are often adjustable and can include substantial hysteresis. That is, the switch's "turn on" point may be much higher than the "shut off" point. This minimizes the on-off cycling of the associated pump.
Some float switches contain a two-stage switch. As liquid rises to the trigger point of the first stage, the associated pump is activated. If the liquid continues to rise (perhaps because the pump has failed or its discharge is blocked), the second stage will be triggered. This stage may switch off the source of the liquid being pumped, trigger an alarm, or both.
Where level must be sensed inside a pressurized vessel, often a magnet is used to couple the motion of the float to a switch located outside the pressurized volume. In some cases, a rod through a stuffing box can be used to operate a switch, but this creates high drag and has a potential for leakage. Successful float switch installations minimize the opportunity for accumulation of dirt on the float that would impede its motion. Float switch materials are selected to resist the deleterious effects of corrosive process liquids. In some systems, a properly selected and sized float can be used to sense the interface level between two liquids of different density. | 1 | Applied and Interdisciplinary Chemistry |
Compared to natural vegetation, cropland soils are depleted in soil organic carbon (SOC). When soil is converted from natural land or semi-natural land, such as forests, woodlands, grasslands, steppes, and savannas, the SOC content in the soil reduces by about 30–40%. This loss is due to the removal of plant material containing carbon, in terms of harvests. When land use changes, the carbon in the soil will either increase or decrease, and this change will continue until the soil reaches a new equilibrium. Deviations from this equilibrium can also be affected by variated climate.
The decreasing of SOC content can be counteracted by increasing the carbon input. This can be done with several strategies, e.g. leave harvest residues on the field, use manure as fertilizer, or including perennial crops in the rotation. Perennial crops have a larger below ground biomass fraction, which increases the SOC content.
Perennial crops reduce the need for tillage and thus help mitigate soil erosion, and may help increase soil organic matter. Globally, soils are estimated to contain >8,580 gigatons of organic carbon, about ten times the amount in the atmosphere and much more than in vegetation.
Researchers have found that rising temperatures can lead to population booms in soil microbes, converting stored carbon into carbon dioxide. In laboratory experiments heating soil, fungi-rich soils released less carbon dioxide than other soils.
Following carbon dioxide (CO) absorption from the atmosphere, plants deposit organic matter into the soil. This organic matter, derived from decaying plant material and root systems, is rich in carbon compounds. Microorganisms in the soil break down this organic matter, and in the process, some of the carbon becomes further stabilized in the soil as humus - a process known as humification.
On a global basis, it is estimated that soil contains about 2,500 gigatons of carbon. This is greater than 3-fold the carbon found in the atmosphere and 4-fold of that found in living plants and animals. About 70% of the global soil organic carbon in non-permafrost areas is found in the deeper soil within the upper 1 meter and stabilized by mineral-organic associations. | 0 | Theoretical and Fundamental Chemistry |
Sulfate conjugates are a heterogeneous class of polar, anionic organosulfate compounds containing an ester of sulfuric acid. Sulfate conjugates commonly result from the metabolic conjugation of endogenous and exogenous compounds with sulfate (-OSO).
Biosynthesis of sulfate esters requires an activated sulfate donor, usually adenosine 5-phosphosulfate (APS) or 3-phosphoadenosine-5'-phosphosulfate (PAPS). Sulfate esters may be hydrolyzed by sulfatase enzyme to release the parent alcohol and a sulfate ion.
Steroid sulfation is one of the most common of all forms of steroid conjugation. Except for cholesterol, dehydroepiandrosterone sulfate is the most abundant of all plasma steroids. Estrone sulfate is the most abundant of all the estrogens in the human body. Estrone sulfate is synthesized by the enzyme estrone sulfotransferase. | 1 | Applied and Interdisciplinary Chemistry |
The venturi meter and manometer is a common type of flow meter which can be used in many fluid applications to convert differential pressure heads into volumetric flow rate, linear fluid speed, or mass flow rate using Bernoulli's principle. The reading of these meters (in inches of water, for example) can be converted into a differential, or gauge pressure, using the above equations. | 1 | Applied and Interdisciplinary Chemistry |
In 1857 Rudolf Clasius published The Nature of the Motion which We Call Heat. In it he derived the relation for the pressure, , in a gas with particles per unit volume (number density), mass , and mean square speed . He then noted that using the classical laws of Boyle and Charles one could write with a constant of proportionality. Hence temperature was proportional to the average kinetic energy of the particles. This article inspired further work based on the twin ideas that substances are composed of indivisible particles, and that heat is a consequence of the particle motion as governed by Newton's laws. The work, known as the kinetic theory of gases, was done principally by James Clerk Maxwell, and Ludwig Boltzmann. At about the same time J. Willard Gibbs also contributed, and advanced it by converting it into statistical mechanics.
This environment influenced Johannes Diderik van der Waals. After initially pursuing a teaching credential, he was accepted for doctoral studies at the University of Leiden under Pieter Rijke. This led, in 1873, to a dissertation that provided a simple, particle based, equation that described the gas–liquid change of state, the origin of a critical temperature, and the concept of corresponding states. The equation is based on two premises, first that fluids are composed of particles with non-zero volumes, and second that at a large enough distance each particle exerts an attractive force on all other particles in its vicinity. These forces were called by Boltzmann van der Waals cohesive forces.
In 1869 Irish professor of chemistry Thomas Andrews at Queens University Belfast in a paper entitled On the Continuity of the Gaseous and Liquid States of Matter', displayed an experimentally obtained set of isotherms of carbonic acid, HCO, that showed at low temperatures a jump in density at a certain pressure, while at higher temperatures there was no abrupt change; the figure can be seen here. Andrews called the isotherm at which the jump just disappeared the critical point. Given the similarity of the titles of this paper and van der Waals subsequent thesis one might think that van der Waals set out to develop a theoretical explanation of Andrews experiments. However the opposite is true, van der Waals began work by trying to determine a mollecular attraction that appeared in Laplaces theory of capillarity, and only after establishing his equation tested it using Andrews results.
By 1877 sprays of both liquid oxygen and liquid nitrogen had been produced, and a new field of research, low temperature physics, had been opened. The van der Waals equation played a part in all this especially with respect to the liquefaction of hydrogen and helium which was finally achieved in 1908. From measurements of and in two states with the same density, the van der Waals equation produces the values and . Thus from two such measurements of pressure and temperature one could determine and , and from these values calculate the expected critical pressure, temperature, and molar volume. Goodstein summarized this contribution of the van der Waals equation as follows:
Van der Waals was awarded the Nobel Prize in 1910, in recognition of the contribution of his formulation of this "equation of state for gases and liquids".
As noted previously, modern day studies of first order phase changes make use of the van der Waals equation together with the Gibbs criterion, equal chemical potential of each phase, as a model of the phenomenon. This model has an analytic coexistence (saturation) curve expressed parametrically, , that was first obtained by Plank, known to Gibbs, and later derived in a beautifully simple and elegant manner by Lekner. A summary of Lekner's solution is presented in a subsequent section, and a more complete discussion in the Maxwell construction. | 0 | Theoretical and Fundamental Chemistry |
The Chen autoxidation of benzoin had performed a similar experiment with respect to the classical and green versions. It was found that the traffic light and vanishing valentine experiments can become successful regardless of whether a sugar is added. One variation is more rapid, with the number of color change cycles do not last as long as the classical and green versions because the reactants are present in smaller amounts; also, the reducing agent for this experiment is benzoin, which is added to help increase the number of cycles in the solution. Moreover, the usable period in this experiment is quite short. Although the experiment is prepared overnight, the reducing agent can be added at any time to be able to observe the solution more. | 1 | Applied and Interdisciplinary Chemistry |
Ahmad Salahuddin (7 July 1937 – 26 November 1996) was an Indian biochemist who served as a professor of biochemistry and department chairman (1984–1996) at Aligarh Muslim University (AMU) Aligarh, India. He was a Founder Director of Interdisciplinary Biotechnology Unit at AMU in 1984. | 1 | Applied and Interdisciplinary Chemistry |
When the modeling phase is complete, selected systems are validated using a professional third party to provide oversight and to determine how closely the model is able to predict the reality of system performance. System validation uses non-pathogenic surrogates such as MS 2 phage or Bacillus subtilis to determine the Reduction Equivalent Dose within an envelope of flow and transmittance.
To validate effectiveness in drinking water systems, the method described in the EPA UV guidance manual is typically used by US water utilities, whilst Europe has adopted Germany's DVGW 294 standard. For wastewater systems, the NWRI/AwwaRF Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse protocols are typically used, especially in wastewater reuse applications. | 0 | Theoretical and Fundamental Chemistry |
In order to generate a molecular tool to discriminate between Interleukin-6 classic signaling and Interleukin-6 trans-signaling, a cDNA coding for human Interleukin-6 and a cDNA coding for the human soluble Interleukin-6 receptor were connected by a cDNA coding for a 13 amino acids long linker, which was long enough to bridge the 40 Å distance between the COOH terminus of the soluble Interleukin-6 receptor and the NH2 terminus of human Interleukin-6. The generated cDNA was expressed in yeast cells and in mammalian cells and it was shown that. | 1 | Applied and Interdisciplinary Chemistry |
When the cone angle is very small, the flow is nearly parallel everywhere in which case, an exact solution can be found, as shown by Theodore von Kármán and Norton B. Moore in 1932. The solution is more apparent in the cylindrical coordinates (the here is the radial distance from the -axis, and not the density). If is the speed of the incoming flow, then we write , where is a small correction and satisfies
where is the Mach number of the incoming flow. We expect the velocity components to depend only on , i.e., in cylindrical coordinates, which means that we must have , where is a self-similar coordinate. The governing equation reduces to
On the surface of the cone , we must have and conesequently .
In the small-angle approximation, the weak shock cone is given by . The trivial solution for describes the uniform flow upstream of the shock cone, whereas the non-trivial solution satisfying the boundary condition on the solid surface behind the shock wave is given by
We therefore have
exhibiting a logarthmic singularity as The velocity components are given by
The pressure on the surface of the cone is found to be (in this formula, is the density of the incoming gas). | 1 | Applied and Interdisciplinary Chemistry |
Primary alcohols () can be oxidized either to aldehydes () or to carboxylic acids (). The oxidation of secondary alcohols () normally terminates at the ketone () stage. Tertiary alcohols () are resistant to oxidation.
The direct oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an aldehyde hydrate () by reaction with water before it can be further oxidized to the carboxylic acid.
Reagents useful for the transformation of primary alcohols to aldehydes are normally also suitable for the oxidation of secondary alcohols to ketones. These include Collins reagent and Dess-Martin periodinane. The direct oxidation of primary alcohols to carboxylic acids can be carried out using potassium permanganate or the Jones reagent. | 0 | Theoretical and Fundamental Chemistry |
Compared to Bioglass 45S5, silicate 13-93 bioactive glass is composed of a higher composition of SiO and includes KO and MgO. It is commercially available from Mo-Sci Corp. or can be directly prepared by melting a mixture of NaCO, KCO, MgCO, CaCO, SiO and NaHPO · 2HO in a platinum crucible at 1300 °C and quenching between stainless steel plates.
The 13-93 glass has received approval for in vivo use in the USA and Europe. It has more facile viscous flow behavior and a lower tendency to crystallize upon being pulled into fibers. 13-93 bioactive glass powder could be dispersed into a binder to create ink for robocasting or direct ink 3D printing technique. The mechanical properties of the resulting porous scaffolds have been studied in various works of literature.
The printed 13-93 bioactive glass scaffold in the study by Liu et al. was dried in ambient air, fired to 600 °C under the O atmosphere to remove the processing additives, and sintered in air for 1 hour at 700 °C. In the pristine sample, the flexural strength (11 ± 3 MPa) and flexural modulus (13 ± 2 MPa) are comparable to the minimum value of those of trabecular bones while the compressive strength (86 ± 9 MPa) and compressive modulus (13 ± 2 GPa) are close to the cortical bone values. However, the fracture toughness of the as-fabricated scaffold was 0.48 ± 0.04 MPa·m, indicating that it is more brittle than human cortical bone whose fracture toughness is 2–12 MPa·m. After immersing the sample in a simulated body fluid (SBF) or subcutaneous implantation in the dorsum of rats, the compressive strength and compressive modulus decrease sharply during the initial two weeks but more gradually after two weeks. The decrease in the mechanical properties was attributed to the partial conversion of the glass filaments in the scaffolds into a layer mainly composed of a porous hydroxyapatite-like material.
Another work by Kolan and co-workers used selective laser sintering instead of conventional heat treatment. After the optimization of the laser power, scan speed, and heating rate, the compressive strength of the sintered scaffolds varied from 41 MPa for a scaffold with ~50% porosity to 157 MPa for dense scaffolds. The in vitro study using SBF resulted in a decrease in the compressive strength but the final value was similar to that of human trabecular bone.
13-93 porous glass scaffolds were synthesized using a polyurethane foam replication method in the report by Fu et al. The stress-strain relationship was examined in obtained from the compressive test using eight samples with 85 ± 2% porosity. The resultant curve demonstrated a progressive breaking down of the scaffold structure and the average compressive strength of 11 ± 1 MPa, which was in the range of human trabecular bone and higher than competitive bioactive materials for bone repairing such as hydroxyapatite scaffolds with the same extent of pores and polymer-ceramic composites prepared by the thermally induced phase separation (TIPS) method. | 0 | Theoretical and Fundamental Chemistry |
Nuclear spectroscopy are methods that use the nucleus to obtain information of the local structure in matter. Important methods are NMR (see below), Mössbauer spectroscopy and Perturbed angular correlation. These methods use the interaction of the hyperfine field with the nucleus' spin. The field can be magnetic or/and electric and are created by the electrons of the atom and its surrounding neighbours. Thus, these methods investigate the local structure in matter, mainly condensed matter in condensed matter physics and solid state chemistry. | 0 | Theoretical and Fundamental Chemistry |
The fully salt-water load bank dates from an earlier, less regulated and litigious era. To pass current safety legislation requires more enclosed designs.
They are no more dangerous than electrode heaters, which work on the same principle, but with plain water, or electrical immersion heaters, provided the correct precautions are used. This requires connecting the container to both ground and neutral and breaking all poles with a linked over-current circuit breaker. If in the open, safety barriers are required. | 0 | Theoretical and Fundamental Chemistry |
The partial volume of a particular gas in a mixture is the volume of one component of the gas mixture. It is useful in gas mixtures, e.g. air, to focus on one particular gas component, e.g. oxygen.
It can be approximated both from partial pressure and molar fraction:
* V is the partial volume of an individual gas component X in the mixture
* V is the total volume of the gas mixture
* p is the partial pressure of gas X
* p is the total pressure of the gas mixture
* n is the amount of substance of gas X
* n is the total amount of substance in the gas mixture | 0 | Theoretical and Fundamental Chemistry |
Vanadium tetrachloride is the inorganic compound with the formula VCl. This reddish-brown liquid serves as a useful reagent for the preparation of other vanadium compounds. | 0 | Theoretical and Fundamental Chemistry |
"Screaming Jelly Babies" (British English), also known as "Growling Gummy Bears" (American and Canadian English), is a classroom chemistry demonstration which is practiced in schools around the world. It is often used at open evenings to show the more engaging and entertaining aspects of science in secondary education settings.
The experiment shows the amount of energy there is in a piece of candy. Jelly babies or gummy bears are often used for theatrics. Potassium chlorate, a strong oxidising agent, rapidly oxidises the sugar in the candy causing it to burst into flames. The reaction produces a "screaming" sound as rapidly expanding gases are emitted from the test tube. The aroma of caramel is given off. Other carbohydrate or hydrocarbon containing substances can be dropped into test tubes of molten chlorate to produce similar results.
Net Reaction
4 KClO + CHO + 6 O → 4 KCl + 12 CO + 11 HO | 1 | Applied and Interdisciplinary Chemistry |
Lepidodinium viride and its close relatives are dinophytes (see below) that lost their original peridinin chloroplast and replaced it with a green algal derived chloroplast (more specifically, a prasinophyte). Lepidodinium is the only dinophyte that has a chloroplast that's not from the rhodoplast lineage. The chloroplast is surrounded by two membranes and has no nucleomorph—all the nucleomorph genes have been transferred to the dinophyte nucleus. The endosymbiotic event that led to this chloroplast was serial secondary endosymbiosis rather than tertiary endosymbiosis—the endosymbiont was a green alga containing a primary chloroplast (making a secondary chloroplast). | 0 | Theoretical and Fundamental Chemistry |
* Ephemeroptera
* Plecoptera
* Mollusca
* Trichoptera
* Escherichia coli (E. coli)
* Coliform bacteria
* Pimephales promelas (fathead minnow)
* Americamysis bahia (Mysid shrimp)
* Sea urchin
* Protists, e.g. Paratrimastix pyriformis
Biological monitoring metrics have been developed in many places, and one widely used family of measurements for freshwater is the presence and abundance of members of the insect orders Ephemeroptera, Plecoptera and Trichoptera (EPT) (of benthic macroinvertebrates whose common names are, respectively, mayfly, stonefly and caddisfly). EPT indexes will naturally vary from region to region, but generally, within a region, the greater the number of taxa from these orders, the better the water quality. Organisations in the United States, such as EPA. offer guidance on developing a monitoring program and identifying members of these and other aquatic insect orders. Many US wastewater dischargers (e.g., factories, power plants, refineries, mines, municipal sewage treatment plants) are required to conduct periodic whole effluent toxicity (WET) tests.
Individuals interested in monitoring water quality who cannot afford or manage lab scale analysis can also use biological indicators to get a general reading of water quality. One example is the IOWATER volunteer water monitoring program of Iowa, which includes an EPT indicator key.
Bivalve molluscs are largely used as bioindicators to monitor the health of aquatic environments in both fresh water and the marine environments. Their population status or structure, physiology, behaviour or the level of contamination with elements or compounds can indicate the state of contamination status of the ecosystem. They are particularly useful since they are sessile so that they are representative of the environment where they are sampled or placed. A typical project is the U.S. Mussel Watch Programme, but today they are used worldwide.
The Southern African Scoring System (SASS) method is a biological water quality monitoring system based on the presence of benthic macroinvertebrates (EPT). The SASS aquatic biomonitoring tool has been refined over the past 30 years and is now on the fifth version (SASS5) which has been specifically modified in accordance with international standards, namely the ISO/IEC 17025 protocol. The SASS5 method is used by the South African Department of Water Affairs as a standard method for River Health Assessment, which feeds the national River Health Programme and the national Rivers Database. | 0 | Theoretical and Fundamental Chemistry |
In 2019 Albrecht-Schönzart was awarded the Glenn T. Seaborg Award in Nuclear Chemistry for outstanding contributions to nuclear and radiochemistry at the American Chemical Society meeting in Orlando, Florida. The focus of this award was his group's discovery of a fundamental break in the chemistry of actinides that begins at californium. His group is responsible for the majority of transuranium single crystal structures and was the first to apply the use of microdiffraction techniques to compounds of these elements. His team was also the first to report the single crystal structure of a berkelium compound. He was in 2015 elected as a fellow of the Royal Society of Chemistry for contributions including his pioneering work on californium. In 2018, Albrecht-Schönzart was elected a fellow of the American Association for the Advancement of Science and was the preceptor for the ACS Nobel Signature Prize for Graduate Education in Chemistry. He has delivered a number of important endowed lectures throughout the world including the Gerhard and Lisolette Closs Memorial Lecture at the University of Chicago and the George Fischer Baker Lecture at Cornell University. In 2024, he was awarded the M. J. Buerger Award for contributions of exceptional distinction in areas of interest to the American Crystallographic Association. | 0 | Theoretical and Fundamental Chemistry |
In the US, individual states are allowed to develop their own water quality standards based on EPA's recommendations under the Clean Water Act of 1977. Once water quality standards are approved, states are tasked with monitoring their surface waters to determine where impairments occur, and watershed plans called Total Maximum Daily Loads (TMDLs) are developed to direct water quality improvement efforts including changes to allowable bacteria loading by point sources and recommendations for changes to practices that reduce nonpoint-source contributions to bacteria loads. Also, many states have beach monitoring programs to warn swimmers when high levels of indicator bacteria are detected. | 0 | Theoretical and Fundamental Chemistry |
The human disease sickle cell anemia is caused by a genetic mutation in the codon for the sixth amino acid of the blood protein beta-hemoglobin. The normal DNA sequence G-A-G codes for the amino acid glutamate, while the mutation changes the middle adenine to a thymine, leading to the sequence G-T-G (G-U-G in the mRNA). This altered sequence substitutes a valine into the final protein, distorting its structure.
To test for the presence of the mutation in a DNA sample, an ASO probe would be synthesized to be complementary to the altered sequence, here labeled as "S". As a control, another ASO would be synthesized for the normal sequence "A". Each ASO is fully complementary to its target sequence (and will bind strongly), but has a single mismatch against its non-target allele (leading to weaker interaction). The first diagram shows how the "S" probe is fully complementary to the "S" target (top), but is partially mismatched against the "A" target (bottom).
A segment of the beta-hemoglobin genes in the sample DNA(s) would be amplified by PCR, and the resulting products applied to duplicate support membranes as Dot blots. The sample's DNA strands are separated with alkali, and each ASO probe is applied to a different blot. After hybridization, a washing protocol is used which can discriminate between the fully complementary and the mismatched hybrids. The mismatched ASOs are washed off of the blots, while the matched ASOs (and their labels) remain.
In the second diagram, six samples of amplified DNA have been applied to each of the two blots. Detection of the ASO label that remains after washing allows a direct reading of the genotype of the samples, each with two copies of the beta-hemoglobin gene. Samples 1 and 4 only have the normal "A" allele, while samples 3 and 5 have both the "A" and "S" alleles (and are therefore heterozygous carriers of this recessive mutation). Samples 2 and 6 have only the "S" allele, and would be affected by the disease. The small amount of cross hybridization shown is typical, and is considered in the process of interpreting the final results. | 1 | Applied and Interdisciplinary Chemistry |
Magnetic particles loaded with vectors are concentrated on the target cells by the influence of an external magnetic field. The cells then take up genetic material naturally via endocytosis and pinocytosis. Consequently, membrane architecture and structure stays intact, in contrast to other physical transfection methods such as electroporation or gene guns that damage the cell membrane.
The nucleic acids are then released into the cytoplasm by different mechanisms depending upon the formulation used:
# the proton sponge effect caused by cationic polymers coated on the nanoparticles that promote endosome osmotic swelling, disruption of the endosome membrane and intracellular release of DNA form,
# the destabilization of endosome by cationic lipids coated on the particles that release the nucleic acid into cells by flip-flop of cell negative lipids and charge neutralization and
# the viral infection mechanism.
Magnetofection works with cells that are not dividing or slowly dividing, meaning that the genetic materials can go to the cell nucleus without cell division. | 1 | Applied and Interdisciplinary Chemistry |
As noradrenaline is an intermediate on the path to adrenaline, dopamine is on the path to noradrenaline (and hence adrenaline.) In 1957 dopamine was identified in the human brain by researcher Katharine Montagu. In 1958/59 Arvid Carlsson and his group in the Pharmacology Department of the University of Lund, including the medical students Åke Bertler and Evald Rosengren, not only found dopamine in the brain, but also – like noradrenaline in Marthe Vogts exemplary study – in uneven distribution, quite different from the distribution of noradrenaline. This argued for a function beyond an intermediate. The concentration was highest in the corpus striatum, which contained only traces of noradrenaline. Carlssons group had previously found that reserpine, which was known to cause a Parkinsonism syndrome, depleted dopamine (as well as noradrenaline and serotonin) from the brain. They concluded that ″dopamine is concerned with the function of the corpus striatum and thus with the control of motor function″. Thus for the first time the reserpine-induced Parkinsonism in laboratory animals and, by implication, Parkinsons disease in humans was related to depletion of striatal dopamine. A year later Oleh Hornykiewicz, who had been introduced to dopamine by Blaschko and was carrying out a color reaction on extracts of human corpus striatum in the Pharmacological Institute of the University of Vienna, saw the brain dopamine deficiency in Parkinsons disease ″with his own naked eye: Instead of the pink color given by the comparatively high concentrations of dopamine in the control samples, the reaction vials containing the extracts of the Parkinson's disease striatum showed hardly a tinge of pink discoloration″.
In 1970, von Euler and Axelrod were two of three winners of the Nobel Prize in Physiology or Medicine, “for their discoveries concerning the humoral transmitters in the nerve terminals and the mechanism for their storage, release and inactivation”, and in 2000 Carlsson was one of three winners who got the prize “for their discoveries concerning signal transduction in the nervous system”. | 1 | Applied and Interdisciplinary Chemistry |
Ørsted was elected a Fellow of the Royal Society of Edinburgh in March 1821, a Foreign Member of the Royal Society of London in April 1821, a foreign member of the Royal Swedish Academy of Sciences in 1822, a member of the American Philosophical Society in 1829, and a Foreign Honorary Member of the American Academy of Arts and Sciences in 1849.
He founded the (Society for the Dissemination of Natural Science, SNU) in 1824. He was also the founder of predecessor organizations which eventually became the Danish Meteorological Institute and the Danish Patent and Trademark Office. In 1829, Ørsted founded (College of Advanced Technology), which was later renamed the Technical University of Denmark (DTU).
In 1824, Ørsted made a significant contribution to chemistry by being the first person to successfully produce aluminium in its metallic state, albeit in a less-than-pure form. In 1808, Humphry Davy had predicted the existence of the metal which he gave the name of alumium. However his attempts to isolate it using electrolysis processes were unsuccessful; the closest he came was an aluminium-iron alloy. Ørsted succeeded in isolating the metallic form by reacting aluminium chloride with potassium amalgam (an alloy of potassium and mercury) and then boiling away the mercury, which left small "chunks" of metal that he described as appearing similar to tin. He presented his results and a sample of the metal at meetings of the Danish Academy of Sciences in early 1825, but otherwise appears to have considered his discovery to be of limited importance. This ambivalence, coupled with the limited audience for the Danish Academy's journal in which the results had been published, meant that the discovery went mostly unnoticed by the wider scientific community at the time. Busy with other work, in 1827 Ørsted gave his friend, the German chemist Friedrich Wöhler, permission to take over the research. Wöhler was able to produce approximately of aluminium powder soon thereafter, using a process of his own design, before finally, in 1845, isolating a quantity of solid metal sufficient for him to describe some of its physical properties.
Ørsted died in Copenhagen in 1851, aged 73, and was buried in the Assistens Cemetery. | 1 | Applied and Interdisciplinary Chemistry |
Calcite changes to calcite-II and calcite-III at pressures of 1.5, and 2.2 GPa. Siderite undergoes a chemical change at 10 GPa at 1800K to form FeO. Dolomite decomposes 7GPa and below 1000 °C to yield aragonite and magnesite. However, there are forms of iron containing dolomite stable at higher pressures and temperatures. Over 130 GPa aragonite undergoes a transformation to a SP tetrahedrally connected carbon, in a covalent network in a C222 structure. Magnesite can survive 80 GPa, but with more than 100 GPa (as at a depth of 1800 km it changes to forms with three-member rings of CO tetrahedra (CO). If iron is present in this mineral, at these pressures it will convert to magnetite and diamond. Melted carbonates with SP carbon are predicted to be very viscous.
Some minerals that contain both silicate and carbonate exist, spurrite and tilleyite. But high-pressure forms have not been studied. There have been attempts to make silicon carbonate. Six coordinated silicates mixed with carbonate should not exist on Earth, but may exist on more massive planets. | 0 | Theoretical and Fundamental Chemistry |
Heat-Mass Analogy:
Because the Nu and Sh equations are derived from these analogous governing equations, one can directly swap the Nu and Sh and the Pr and Sc numbers to convert these equations between mass and heat.
In many situations, such as flow over a flat plate, the Nu and Sh numbers are functions of the Pr and Sc numbers to some coefficient . Therefore, one can directly calculate these numbers from one another using:
Where can be used in most cases, which comes from the analytical solution for the Nusselt Number for laminar flow over a flat plate. For best accuracy, n should be adjusted where correlations have a different exponent.
We can take this further by substituting into this equation the definitions of the heat transfer coefficient, mass transfer coefficient, and Lewis number, yielding:
For fully developed turbulent flow, with n=1/3, this becomes the Chilton–Colburn J-factor analogy. Said analogy also relates viscous forces and heat transfer, like the Reynolds analogy. | 1 | Applied and Interdisciplinary Chemistry |
Silica monoliths have only been commercially available since 2001, when Merck began their Chromolith campaign. The Chromolith technology was licensed from Soga and Nakanishi's group at Kyoto University. The new product won the PittCon Editors’ Gold Award for Best New Product, as well as an R&D 100 Award, both in 2001.
Individual monolith columns have a life cycle that generally exceeds that of its particulate competitors. When selecting an HPLC column supplier, column lifetime was second only to column-to-column reproducibility in importance to the purchaser. Chromolith columns, for example, have demonstrated reproducibility of 3,300 sample injections and 50,000 column volumes of mobile phase. Also important to the life cycle of the monolith is its increased mechanical robustness; polymeric monoliths are able to withstand pH ranges from 1 to 14, can endure elevated temperatures, and do not need to be handled delicately. “Monoliths are still teenagers,” affirms Frantisec Svec, a leader in the field of novel stationary phases for LC. | 0 | Theoretical and Fundamental Chemistry |
Dithiofluorescein (sometimes generically called thiofluorescein) is a complexometric indicator used in analytical chemistry. It changes from blue to colorless when it binds to mercury(2+) ions. It thus can indicate the endpoint in the titration of thiols using o-hydroxymercuribenzoic acid or its sodium salt. The reagent can be immobilized t in a polymer on a fiber optic, which might allow development of a detector for sulfide ions in a flow cell. Unlike fluorescein and other related fluoran dyes that have oxygen substituents on the benzene rings, dithiofluorescein, which has sulfur substituents, is not fluorescent. | 0 | Theoretical and Fundamental Chemistry |
β-Leucine (beta-leucine) is a beta amino acid and positional isomer of -leucine which is naturally produced in humans via the metabolism of -leucine by the enzyme leucine 2,3-aminomutase. In cobalamin (vitamin B) deficient individuals, plasma concentrations of β-leucine are elevated. | 1 | Applied and Interdisciplinary Chemistry |
Both slow variants (GCaMP6s, jGCaMP7s) and fast variants (GCaMP6f, jGCaMP7f) are used in biological and neuroscience research. The slow variants are brighter and more sensitive to small changes in Ca levels, such as single action potentials; on the other hand, the fast variants are less sensitive but respond more quickly, making them useful for tracking changes in Ca levels over precise timescales. GCaMP6 also has a medium variant, GCaMP6m, whose kinetics are intermediate between GCaMP6s and GCaMP6f. Other variants of jGCaMP7 are also employed: jGCaMP7b exhibits bright baseline fluorescence and is used for imaging dendrites and axons, while jGCaMP7c exhibits greater contrast between maximal and baseline fluorescence and is advantageous for imaging large populations of neurons.
In 2018, Yang et al. reported the development of GCaMP-X, generated by the addition of a calmodulin-binding motif. Since the GCaMP calmodulin domain, when unbound, disrupts L-type calcium channel gating, the added calmodulin-binding motif prevents GCaMP-X from interfering with calcium-dependent signaling mechanisms.
In 2020, Zhang et al. reported the development of jGCaMP8, including sensitive, medium, and fast variants, which exhibit faster kinetics and greater sensitivity than the corresponding jGCaMP7 variants.
Red fluorescent indicators have also been developed: jRCaMP1a and jRCaMP1b use a circular permutation of the red fluorescent protein mRuby instead of GFP, while jRGECO1a is based on the red fluorescent protein mApple. Since the blue light used to excite GCaMP is scattered by tissue and the emitted green light is absorbed by blood, red fluorescent indicators provide more penetration and imaging depth in vivo than GCaMP. Use of red fluorescent indicators also avoids the photodamage caused by blue excitation light. Moreover, red fluorescent indicators allow for concurrent use of optogenetics, which is difficult with GCaMP because the excitation wavelengths of GCaMP overlap with those of channelrhodopsin-2 (ChR2). Simultaneous use of red and green GECIs can provide two-color visualization of different subcellular regions or cell populations. | 1 | Applied and Interdisciplinary Chemistry |
Among its few known reactions, CS reacts with bromine to form the cyclic disulfide.
CS polymerizes under applied pressure to give a black semi-conducting solid. A similar pressure-induced polymerization of CS also gives a black semiconducting polymer.
In addition, reactions of CS can yield highly condensed sulfur-containing compounds, e.g. the reaction of CS with 2-aminopyridine.
Using microwave spectroscopy, small CS clusters have been detected in interstellar medium. The rotational transitions of these molecular carbon sulfides matched with the corresponding molecules. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, the alkoxy group is an alkyl group which is singularly bonded to oxygen; thus . Denoted usually with apostrophe('). The range of alkoxy groups is vast, the simplest being methoxy (). An ethoxy group () is found in the organic compound ethyl phenyl ether (, also known as ethoxybenzene).
Related to alkoxy groups are aryloxy groups, which have an aryl group singularly bonded to oxygen such as the phenoxy group ().
An alkoxy or aryloxy group bonded to an alkyl or aryl () is an ether. If bonded to H it is an alcohol.
An alkoxide can refer to salts of alcohols, and they are ionic compounds containing an alkoxide ions ; it is a derivative of an alcohol where the hydrogen of the –OH group is replaced by a metal, for example sodium salt of ethanol () is sodium ethoxide, containing ethoxide anions and sodium cations . | 0 | Theoretical and Fundamental Chemistry |
Figure 15 shows four sketches Kneass drew of steam passing through a nozzle. In general, compressible flows through a diverging duct increases velocity as a gas expands. The two sketches at the bottom of figure 15 are both diverging, but the bottom one is slightly curved, and produced the highest velocity flow parallel to the axis. The area of a duct is proportional to the square of the diameter, and the curvature allows the steam to expand more linearly as it passes through the duct.
An ideal gas cools during adiabatic expansion (without adding heat), releasing less energy than the same gas would during isothermal expansion (constant temperature). Expansion of steam follows an intermediate thermodynamic process called the Rankine cycle. Steam does more work than an ideal gas, because steam remains hot during expansion.
The extra heat comes from enthalpy of vaporization, as some of the steam condenses back into dropplets of water intermixed with steam. | 1 | Applied and Interdisciplinary Chemistry |
Schwab's academic career was prolific in the many fields he became involved with; most famous were his contributions to the understanding and kinetics of phenomena relating to heterogeneous catalysis. In his career he published a total of more than 250 papers in eminent chemical journals. | 0 | Theoretical and Fundamental Chemistry |
Ostwalds law of dilution, which gives the dissociation constant of a weak electrolyte as a function of concentration, can be written in terms of molar conductivity. Thus, the pK values of acids can be calculated by measuring the molar conductivity and extrapolating to zero concentration. Namely, pK = p() at the zero-concentration limit, where K is the dissociation constant from Ostwalds law. | 0 | Theoretical and Fundamental Chemistry |
Flocculation is used in biotechnology applications in conjunction with microfiltration to improve the efficiency of biological feeds. The addition of synthetic flocculants to the bioreactor can increase the average particle size making microfiltration more efficient. When flocculants are not added, cakes form and accumulate causing low cell viability. Positively charged flocculants work better than negatively charged ones since the cells are generally negatively charged. | 1 | Applied and Interdisciplinary Chemistry |
The goal of spectral density estimation is to estimate the spectral density of a random signal from a sequence of time samples. Depending on what is known about the signal, estimation techniques can involve parametric or non-parametric approaches, and may be based on time-domain or frequency-domain analysis. For example, a common parametric technique involves fitting the observations to an autoregressive model. A common non-parametric technique is the periodogram.
The spectral density is usually estimated using Fourier transform methods (such as the Welch method), but other techniques such as the maximum entropy method can also be used. | 0 | Theoretical and Fundamental Chemistry |
The Ohnesorge number for a 3 mm diameter rain drop is typically ~0.002. Larger Ohnesorge numbers indicate a greater influence of the viscosity.
This is often used to relate to free surface fluid dynamics such as dispersion of liquids in gases and in spray technology.
In inkjet printing, liquids whose Ohnesorge number are in the range 0.1 < Oh < 1.0 are jettable (1<Z<10 where Z is the reciprocal of the Ohnesorge number). | 1 | Applied and Interdisciplinary Chemistry |
* 2005 NSF-CAREER Award of the American National Science Foundation
* 2009 Peter Mark Memorial Award, American Vacuum Society
* 2009 University of Central Florida, Research Incentive Award
* 2016 Fellow of the Max Planck Society at the Max Planck Institute for Chemical Energy Conversion (Mülheim, Germany)
* 2016 European Research Council Consolidator Award
*2020 Elected Member of the Academia Europaea, the Academy of Europe
*2021 ISE-Elsevier Prize for Experimental Electrochemistry of the International Society of Electrochemistry (ISE)
*2022 Paul H. Emmett Award from the North American Catalysis Society for Fundamental Catalysis | 0 | Theoretical and Fundamental Chemistry |
NPP1 helps scavenge extracellular nucleotides in order to meet the high purine and pyrimidine requirements of dividing cells. In T-cells, it may scavenge NAD from nearby dead cells as a source of adenosine.
The pyrophosphate produced by NPP1 in bone cells is thought to serve as both a phosphate source for calcium phosphate deposition and as an inhibitory modulator of calcification. NPP1 appears to be important for maintaining pyrophosphate/phosphate balance. Overactivity of the enzyme is associated with chondrocalcinosis, while deficiency correlates to pathological calcification.
NPP1 inhibits the insulin receptor in vitro. In 2005, overexpression of the isoform was implicated in insulin resistance in mice. It has been linked to insulin resistance and Type 2 diabetes in humans. | 1 | Applied and Interdisciplinary Chemistry |
Mitotic spindle assembly checkpoint protein MAD1 is a protein that in humans is encoded by the MAD1L1 gene.
MAD1L1 is also known as Human Accelerated Region 3. It may have played a key role in the evolution of humans from apes. | 1 | Applied and Interdisciplinary Chemistry |
The ionizing effect of radiation on a gas is extensively used for the detection of radiation such as alpha, beta, gamma, and X-rays. The original ionization event in these instruments results in the formation of an "ion pair"; a positive ion and a free electron, by ion impact by the radiation on the gas molecules. The ionization chamber is the simplest of these detectors, and collects all the charges created by direct ionization within the gas through the application of an electric field.
The Geiger–Müller tube and the proportional counter both use a phenomenon known as a Townsend avalanche to multiply the effect of the original ionizing event by means of a cascade effect whereby the free electrons are given sufficient energy by the electric field to release further electrons by ion impact. | 0 | Theoretical and Fundamental Chemistry |
Fluorine-18 is one of the early tracers used in positron emission tomography (PET), having been in use since the 1960s.
Its significance is due to both its short half-life and the emission of positrons when decaying.
A major medical use of fluorine-18 is: in positron emission tomography (PET) to image the brain and heart; to image the thyroid gland; as a radiotracer to image bones and seeking cancers that have metastasized from other locations in the body and in radiation therapy treating internal tumors.
Tracers include sodium fluoride which can be useful for skeletal imaging as it displays high and rapid bone uptake accompanied by very rapid blood clearance, which results in a high bone-to-background ratio in a short time and
fluorodeoxyglucose (FDG), where the F substitutes a hydroxyl.
New dioxaborolane chemistry enables radioactive fluoride (F) labeling of antibodies, which allows for positron emission tomography (PET) imaging of cancer. A uman-erived, enetic, ositron-emitting and luorescent (HD-GPF) reporter system uses a human protein, PSMA and non-immunogenic, and a small molecule that is positron-emitting (F) and fluorescent for dual modality PET and fluorescence imaging of genome modified cells, e.g. cancer, CRISPR/Cas9, or CAR T-cells, in an entire mouse. The dual-modality small molecule targeting PSMA was tested in humans and found the location of primary and metastatic prostate cancer, fluorescence-guided removal of cancer, and detects single cancer cells in tissue margins. | 1 | Applied and Interdisciplinary Chemistry |
By 2007 the use of economic evaluation methods regarding public-funding of orphan drugs, using estimates of the incremental cost-effectiveness, for example, became more established internationally. The QALY has often been used in cost-utility analysis to calculate the ratio of cost to QALYs saved for a particular health care intervention. By 2008 the National Institute for Health and Care Excellence (NICE) in England and Wales, for example, operated with a threshold range of £20,000–30,000 per quality-adjusted life year (QALY). By 2005 doubts were raised about the use of economic evaluations in orphan drugs. By 2008 most of the orphan drugs appraised had cost-effectiveness thresholds "well in excess of the accepted level and would not be reimbursed according to conventional criteria". As early as 2005 McCabe et al. argued that rarity should not have a premium and orphan drugs should be treated like other pharmaceuticals in general. Drummond et al. argued that the social value of health technologies should also be included in the assessment along with the estimation of the incremental cost-effectiveness ratio. | 1 | Applied and Interdisciplinary Chemistry |
Consider slender body of length and typical diameter with , surrounded by fluid of viscosity whose motion is governed by the Stokes equations. Note that the Stokes' paradox implies that the limit of infinite aspect ratio is singular, as no Stokes flow can exist around an infinite cylinder.
Slender-body theory allows us to derive an approximate relationship between the velocity of the body at each point along its length and the force per unit length experienced by the body at that point.
Let the axis of the body be described by , where is an arc-length coordinate, and is time. By virtue of the slenderness of the body, the force exerted on the fluid at the surface of the body may be approximated by a distribution of Stokeslets along the axis with force density per unit length. is assumed to vary only over lengths much greater than , and the fluid velocity at the surface adjacent to is well-approximated by .
The fluid velocity at a general point due to such a distribution can be written in terms of an integral of the Oseen tensor (named after Carl Wilhelm Oseen), which acts as a Greens function for a single Stokeslet. We have
where is the identity tensor.
Asymptotic analysis can then be used to show that the leading-order contribution to the integral for a point on the surface of the body adjacent to position comes from the force distribution at . Since , we approximate . We then obtain
where .
The expression may be inverted to give the force density in terms of the motion of the body:
Two canonical results that follow immediately are for the drag force on a rigid cylinder (length , radius ) moving a velocity either parallel to its axis or perpendicular to it. The parallel case gives
while the perpendicular case gives
with only a factor of two difference.
Note that the dominant length scale in the above expressions is the longer length ; the shorter length has only a weak effect through the logarithm of the aspect ratio. In slender-body theory results, there are corrections to the logarithm, so even for relatively large values of the error terms will not be that small. | 1 | Applied and Interdisciplinary Chemistry |
The 4th analytical group of cations includes ions which form sulfides that are insoluble at high concentrations. The reagents used are HS in the presence of NHOH. NHOH is used to increase the concentration of the sulfide ion, by the common ion effect - hydroxide ions from NHOH combine with H ions from HS, which shifts the equilibrium in favor of the ionized form:
They contain Zn, Mn, Ni and Co | 0 | Theoretical and Fundamental Chemistry |
A protocell (or protobiont) is a self-organized, endogenously ordered, spherical collection of lipids proposed as a rudimentary precursor to cells during the origin of life. A central question in evolution is how simple protocells first arose and how their progeny could diversify, thus enabling the accumulation of novel biological emergences over time (i.e. biological evolution). Although a functional protocell has not yet been achieved in a laboratory setting, the goal to understand the process appears well within reach.
A protocell is a pre-cell in abiogenesis, and was a contained system consisting of simple biologically relevant molecules like ribozymes, and encapsulated in a simple membrane structure – isolating the entity from the environment and other individuals – thought to consist of simple fatty acids, mineral structures, or rock-pore structures. | 0 | Theoretical and Fundamental Chemistry |
Section A on Cryogenics and Liquefied Gases focuses on refrigeration science and technology at low temperatures: the cryogenic domain spans the lower part of the temperature scale, from absolute zero to 120 K, thus encompassing the normal boiling points of air gases as well as of liquid natural gas (LNG).
Section A comprises two Commissions, A1 Cryophysics and Cryoengineering, and A2 Liquefaction and Separation of Gases. Commission A1 deals with research, development and industrial activities at the lowest temperatures, including low-temperature physics, applications of superconductivity and helium cryogenics. Commission A2 essentially covers the liquefied gas industry, including air separation and LNG technology, two mature domains with high economic stakes and ongoing developments addressing important societal issues such as energy efficiency and carbon sequestration.
Section A also maintains and develops relations with other Sections of the IIR, mainly Commission B1 Thermodynamics and Transfer Processes in the field of thermodynamics and transfer processes, essential tools of the cryogenic engineer, and Commission C1 Cryobiology, Cryomedicine and Health Products for the cooling of biological specimens and living tissues for preservation or treatment which require implementing cryogenic processes. Section A consists of a panel of multidisciplinary professionals and experts in sciences and technologies such as thermodynamics, condensed matter physics, materials science, heat transfer, fluid dynamics, vacuum and leak-tightness, instrumentation and process control, applied to the low-temperature domain.
* Commission A1: Cryophysics and Cryoengineering
Commission A1 on Cryophysics and Cryoengineering deals with research, development and industrial activities at the lowest temperatures, including low-temperature physics, applications of superconductivity and helium cryogenics.
* Commission A2: Liquefaction and Separation of Gases
The work of Commission A2 Liquefaction and Separation of Gases reflects world-wide activities in the domain of separation of gases and liquefaction. Apart from the personal involvement of Commission members in various projects, the commission is present at conferences, workshops and seminars: LNG International Exhibition and Conference, GASTECH, Cryogenics, Cryogen Expos, European Cryogenic Course and others.
The commission is close to academia, industry and end users of separated and liquefied gases.
Commission members work closely with Commission A1 Cryophysics, Cryoengineering and Commission C1 Cryobiology, Cryomedicine and Health Products. | 0 | Theoretical and Fundamental Chemistry |
Lineatin is a pheromone produced by female striped ambrosia beetle, Trypodendron lineatum Olivier. These kinds of beetles are responsible for extensive damage of coniferous forest infestation in Europe and North America. Since lineatin can act as lures used for mass-trapping of T. lineatum, it is being studied to apply as a pest control reagent. | 0 | Theoretical and Fundamental Chemistry |
Half sandwich complexes containing cyclopentadienyl ligands are common. Well studied examples include (η-CH)V(CO), (η-CH)Cr(CO)H, (η-CHCH)Mn(CO), (η-CH)Cr(CO)H, [(η-CH)Fe(CO)], (η-CH)V(CO)I, and (η-CH)Ru(NCMe). (η-CH)Co(CO) is a two-legged piano stool complex. Bulky cyclopentadienyl ligands such as 1,2,4-CH(tert-Bu) form unusual half-sandwich complexes. | 0 | Theoretical and Fundamental Chemistry |
Eutrophication may cause competitive release by making abundant a normally limiting nutrient. This process causes shifts in the species composition of ecosystems. For instance, an increase in nitrogen might allow new, competitive species to invade and out-compete original inhabitant species. This has been shown to occur in New England salt marshes. In Europe and Asia, the common carp frequently lives in naturally eutrophic or hypereutrophic areas, and is adapted to living in such conditions. The eutrophication of areas outside its natural range partially explain the fish's success in colonizing these areas after being introduced. | 1 | Applied and Interdisciplinary Chemistry |
Industrial ecology is the notion that major manufacturing and industrial processes need to shift from open loop systems to closed loop systems. This is essentially the recycling of waste to make new products. This reduces refuse and increases the effectiveness of resources. ESEM looks to minimize the impact of industrial processes on the environment, therefore the notion of recycling of industrial products is important to ESEM. | 1 | Applied and Interdisciplinary Chemistry |
A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals. The input signal that most common spectrum analyzers measure is electrical; however, spectral compositions of other signals, such as acoustic pressure waves and optical light waves, can be considered through the use of an appropriate transducer. Spectrum analyzers for other types of signals also exist, such as optical spectrum analyzers which use direct optical techniques such as a monochromator to make measurements.
By analyzing the spectra of electrical signals, dominant frequency, power, distortion, harmonics, bandwidth, and other spectral components of a signal can be observed that are not easily detectable in time domain waveforms. These parameters are useful in the characterization of electronic devices, such as wireless transmitters.
The display of a spectrum analyzer has frequency displayed on the horizontal axis and the amplitude on the vertical axis. To the casual observer, a spectrum analyzer looks like an oscilloscope, which plots amplitude on the vertical axis but time on the horizontal axis. In fact, some lab instruments can function either as an oscilloscope or a spectrum analyzer. | 0 | Theoretical and Fundamental Chemistry |
Analytical Chemistry is a biweekly peer-reviewed scientific journal published since 1929 by the American Chemical Society. Articles address general principles of chemical measurement science and novel analytical methodologies. Topics commonly include chemical reactions and selectivity, chemometrics and data processing, electrochemistry, elemental and molecular characterization, imaging, instrumentation, mass spectrometry, microscale and nanoscale systems, -omics, sensing, separations, spectroscopy, and surface analysis. It is abstracted and indexed in Chemical Abstracts Service, CAB International, EBSCOhost, ProQuest, PubMed, Scopus, and the Science Citation Index Expanded. According to the Journal Citation Reports, it has a 2022 impact factor of 7.4. The editor-in-chief is Jonathan V. Sweedler (University of Illinois). | 0 | Theoretical and Fundamental Chemistry |
*1,2-dipolar compounds have the opposite charges on adjacent atoms.
*1,3-dipolar compounds have the charges separated over three atoms. They are reactants in 1,3-dipolar cycloadditions.
*Also 1,4-dipolars, 1,5-dipolars, and so on exist. | 0 | Theoretical and Fundamental Chemistry |
In 2016, New York, along with Vermont and New Hampshire, acknowledged PFOA contamination by requesting the EPA to release water quality guidance measures. Contamination has been observed by the New York State Department of Environmental Conservation in Hoosick Falls, Newburgh, Petersburgh, Poestenkill, Mahopac, and Armonk.
The village of Hoosick Falls has received a $65.25 million dollar settlement from Saint-Gobain Performance Plastics, Honeywell, 3M, and DuPont companies through a class action lawsuit in 2021, due to the disposal of PFAS chemicals into the groundwater of the local water treatment plant. | 0 | Theoretical and Fundamental Chemistry |
After graduating from Auckland University College with a Master of Science with second-class honours in 1928, he received funding to research manuka oil the following year, and undertook independent research at Massey Agricultural College from 1929 to 1930.
He then went to the Dyson Perrins Laboratory at Oxford University for a PhD under Robert Robinson, investigating the chemical structure of strychnine. He was awarded his doctorate in 1932 and returned to Auckland, where he was appointed as a lecturer in organic chemistry in 1933.
In 1941 he was awarded a DSc from Auckland University College. He was elected a Fellow of the Royal Society of New Zealand in 1942 and served as its president from 1956 to 1958. He was awarded the Hector Medal by the society in 1943. In 1953, he was awarded the Queen Elizabeth II Coronation Medal.
He was also an active member of the Auckland University field club. | 0 | Theoretical and Fundamental Chemistry |
It is recommended that polymorphs are identified (e.g. for where the two forms zincblende (cubic) and wurtzite (hexagonal)), as and respectively. | 0 | Theoretical and Fundamental Chemistry |
Extremely high temperatures are reached by the D-gun (≈4000 °C) whilst in operation. Flammable and explosive fuels (generally acetylene) are used in detonation spraying to produce the supersonic shockwave that propels the powder coating materials onto their target components. This poses a serious burn and explosion hazard. Again, no-one should be present in the room whilst the D-gun is in operation and the room should be designed to withstand any malfunction of the D-gun. Also protective gloves should be used to handle the D-gun and sprayed components to void burns form hot components after spraying. | 1 | Applied and Interdisciplinary Chemistry |
A colour-indicator titration, for example using test method ASTM D974, can be carried out to indicate relative changes that occur in an oil sample during its use under oxidising conditions. A sample is dissolved in a solvent mixture of Toluene/ Propan-2-ol with 0.5% deionised water. A methyl orange indicator is added and the solution is titrated using alcoholic potassium hydroxide. The end point is indicated by a colour change from orange to green. | 0 | Theoretical and Fundamental Chemistry |
Calculation can be employed to determine the nuclear binding energy of nuclei. The calculation involves determining the mass defect, converting it into energy, and expressing the result as energy per mole of atoms, or as energy per nucleon. | 0 | Theoretical and Fundamental Chemistry |
Traditionally, enhancers were identified by enhancer trap techniques using a reporter gene or by comparative sequence analysis and computational genomics. In genetically tractable models such as the fruit fly Drosophila melanogaster, for example, a reporter construct such as the lacZ gene can be randomly integrated into the genome using a P element transposon. If the reporter gene integrates near an enhancer, its expression will reflect the expression pattern driven by that enhancer. Thus, staining the flies for LacZ expression or activity and cloning the sequence surrounding the integration site allows the identification of the enhancer sequence.
The development of genomic and epigenomic technologies, however, has dramatically changed the outlook for cis-regulatory modules (CRM) discovery. Next-generation sequencing (NGS) methods now enable high-throughput functional CRM discovery assays, and the vastly increasing amounts of available data, including large-scale libraries of transcription factor-binding site (TFBS) motifs, collections of annotated, validated CRMs, and extensive epigenetic data across many cell types, are making accurate computational CRM discovery an attainable goal. An example of NGS-based approach called DNase-seq have enabled identification of nucleosome-depleted, or open chromatin regions, which can contain CRM. More recently techniques such as ATAC-seq have been developed which require less starting material. Nucelosome depleted regions can be identified in vivo through expression of Dam methylase, allowing for greater control of cell-type specific enhancer identification.
Computational methods include comparative genomics, clustering of known or predicted TF-binding sites, and supervised machine-learning approaches trained on known CRMs.
All of these methods have proven effective for CRM discovery, but each has its own considerations and limitations, and each is subject to a greater or lesser number of false-positive identifications.
In the comparative genomics approach, sequence conservation of non-coding regions can be indicative of enhancers. Sequences from multiple species are aligned, and conserved regions are identified computationally. Identified sequences can then be attached to a reporter gene such as green fluorescent protein or lacZ to determine the in vivo pattern of gene expression produced by the enhancer when injected into an embryo. mRNA expression of the reporter can be visualized by in situ hybridization, which provides a more direct measure of enhancer activity, since it is not subjected to the complexities of translation and protein folding. Although much evidence has pointed to sequence conservation for critical developmental enhancers, other work has shown that the function of enhancers can be conserved with little or no primary sequence conservation. For example, the RET enhancers in humans have very little sequence conservation to those in zebrafish, yet both species' sequences produce nearly identical patterns of reporter gene expression in zebrafish. Similarly, in highly diverged insects (separated by around 350 million years), similar gene expression patterns of several key genes was found to be regulated through similarly constituted CRMs although these CRMs do not show any appreciable sequence conservation detectable by standard sequence alignment methods such as BLAST. | 1 | Applied and Interdisciplinary Chemistry |
Isotope effect is observed when molecules containing heavier isotopes of the same atoms (for example, deuterium instead of hydrogen) are engaged in a chemical reaction at a slower rate. Deuterium-reinforced lipids can be used for the protection of living cells by slowing the chain reaction of lipid peroxidation. The lipid bilayer of the cell and organelle membranes contain polyunsaturated fatty acids (PUFA) are key components of cell and organelle membranes. Any process that either increases oxidation of PUFAs or hinders their ability to be replaced can lead to serious disease. Correspondingly, drugs that stop the chain reaction of lipid peroxidation have preventive and therapeutic potential. | 0 | Theoretical and Fundamental Chemistry |
The first disproportionation reaction to be studied in detail was:
This was examined using tartrates by Johan Gadolin in 1788. In the Swedish version of his paper he called it . | 0 | Theoretical and Fundamental Chemistry |
After 1908, Ostwald redirected his philosophy to sociological and cultural phenomena as part of sociological energetics (). He attempted to create a hierarchy to classify the sciences and social sciences based on life, energy and order.
Sociologist Max Weber oppossed Ostwald views. In 1909, Weber accussed sociological energetics of being ideological, underrating the complexity of the social sciences and overrating the importance of recasting phenomena in energetic terminology. Weber also objects to the idea of psychological energy to explain psychology and accusses Ostwald of trying to derive an is from an ought. | 1 | Applied and Interdisciplinary Chemistry |
Transmethylation is a biologically important organic chemical reaction in which a methyl group is transferred from one compound to another.
An example of transmethylation is the recovery of methionine from homocysteine. In order to sustain sufficient reaction rates during metabolic stress, this reaction requires adequate levels of vitamin B and folate. Methyl tetrahydrofolate delivers methyl groups to form the active methyl form of vitamin B that is required for methylation of homocysteine. Deficiencies of vitamin B or folate cause increased levels of circulating homocysteine. Elevated homocysteine is a risk factor for cardiovascular disease and is linked to the metabolic syndrome (insulin insensitivity).
Transmethylation is decreased sometimes in parents of children with autism. | 0 | Theoretical and Fundamental Chemistry |
The identification of synexpression groups has affected the way some scientists view evolutionary change in higher eukaryotes. Since groups of genes involved in the same biological process often share one or more common control elements, it has been suggested that the differential expression of these synexpression groups in different tissues of organisms can contribute to co-evolution tissues, organs, and appendages. Today it is commonly believed that it is not primarily the gene products themselves that evolve, but that it is the control networks for groups of genes that contribute most to the evolution of higher eukaryotes. | 1 | Applied and Interdisciplinary Chemistry |
* Along with Thénard, Gay Lussac received 30,000 francs from Napoleon in the third edition of the Galvanism Prize in 1809 for their research.
* In Paris, a street and a hotel near the Sorbonne are named after him as are a square and a street in his birthplace, Saint-Léonard-de-Noblat
* In Australia, the "Gay-Lussac Room" at AB Mauri STC, Sydney was named after him in honor of his work with yeast fermentation. | 1 | Applied and Interdisciplinary Chemistry |
The amylolytic process is used in the brewing of alcohol from grains. Since grains contain starches but little to no simple sugars, the sugar needed to produce alcohol is derived from starch via the amylolytic process. In beer brewing, this is done through malting. In sake brewing, the mold Aspergillus oryzae provides amylolysis, and in Tapai, Saccharomyces cerevisiae. The amylolytic process can also be used to allow for maximum results in production. For instance, glucose formation, when amylolytic enzymes are added to a given compound, the enzymes work to give maximum formation. The amylolytic process is also useful in the breaking down of molecules, it can be closely associated with the process of hydrolysis. | 0 | Theoretical and Fundamental Chemistry |
Tensioned screen cloth is typically 4 feet by the width or the length of the screening machine depending on whether the deck is side or end tensioned. Screen cloth for tensioned decks can be made with hooks and are attached with clamp rails bolted on both sides of the screen box. When the clamp rail bolts are tightened, the cloth is tensioned or even stretched in the case of some types of self-cleaning screen media. To ensure that the center of the cloth does not tap repeatedly on the deck due to the vibrating shaker and that the cloth stays tensioned, support bars are positioned at different heights on the deck to create a crown curve from hook to hook on the cloth. Tensioned screen cloth is available in various materials: stainless steel, high carbon steel and oil tempered steel wires, as well as moulded rubber or polyurethane and hybrid screens (a self-cleaning screen cloth made of rubber or polyurethane and metal wires).
Commonly, vibratory-type screening equipment employs rigid, circular sieve frames to which woven wire mesh is attached. Conventional methods of producing tensioned meshed screens has given way in recent years to bonding, whereby the mesh is no longer tensioned and trapped between a sieve frame body and clamping ring; instead, developments in modern adhesive technologies has allowed the industry to adopt high strength structural adhesives to bond tensioned mesh directly to frames. | 1 | Applied and Interdisciplinary Chemistry |
Sulfenyl chlorides can be converted to sulfinyl chlorides (RS(O)Cl). In one approach, the sulfinyl chloride is generated in two steps starting with reaction of a thiol () with sulfuryl chloride (). In some cases the sulfenyl chloride results instead, as happens with 2,2,2-trifluoro-1,1-diphenylethanethiol. A trifluoroperacetic acid oxidation then provides a general approach to formation of sulfinyl chlorides from sulfenyl chlorides: | 0 | Theoretical and Fundamental Chemistry |
Reagent test results develop very quickly and due to reactions with moisture and oxygen in air, any changes after the first 60 seconds should be discarded. | 0 | Theoretical and Fundamental Chemistry |
Polyphosphazenes obtained from polymerised hexachlorophosphazene (polydichlorophosphazene) have gathered attention within the field of inorganic polymers and probed investigations on the properties of elastomeric and thermoplastic derivatives. Some of them appear promising for future applications as fibre- or membrane-forming high performance materials, since they combine transparency, backbone flexibility, tunable hydrophilicity or hydrophobicity, and various other desirable properties.
Current commercial applications for polyphosphazene rubber components are in O-rings, fuel lines and shock absorbers, where the polyphosphazenes confer fire resistance, imperviousness to oils and flexibility even at very low temperatures. | 0 | Theoretical and Fundamental Chemistry |
Molecules interact at close range through intermolecular forces (the "van der Waals
forces"), which cause minute shifts of the electron density distributions (relative
the distributions of electrons when the molecules are not interacting).
Intermolecular forces are repulsive at near range, where electron exchange
forces dominate the interaction, and attractive at somewhat greater separations,
where the dispersion forces are active. (If separations are further increased, all
intermolecular forces fall off rapidly and may be totally neglected.)
Repulsion and attraction are due, respectively, to the small defects or
excesses of electron densities of molecular complexes in the space
between the interacting molecules, which often result in interaction-induced
electric dipole moments that contribute some to interaction-induced emission and
absorption intensities. The resulting dipoles are referred to as exchange
force-induced dipole and dispersion force-induced dipoles, respectively.
Other dipole induction mechanisms also exist in molecular (as opposed to
monatomic) gases and in mixtures of gases, when molecular gases are present.
Molecules have centers of positive charge (the nuclei), which are surrounded by
a cloud of electrons. Molecules thus may be thought of being surrounded by various
electric multipolar fields which will polarize any collisional partner
momentarily in a fly-by encounter, generating the so-called multipole-induced
dipoles. In diatomic molecules such as H and N, the lowest-order
multipole moment is the quadrupole, followed by a hexadecapole, etc., hence the
quadrupole-induced, hexadecapole-induced,... dipoles. Especially the former is often
the strongest, most significant of the induced dipoles contributing to CIA and CIE.
Other induced dipole mechanisms exist. In collisional systems involving
molecules of three or more atoms (CO, CH...), collisional frame
distortion may be an important induction mechanism. Collision-induced
emission and absorption by simultaneous collisions of three or more particles
generally do involve pairwise-additive dipole components, as well as important
irreducible dipole contributions and their spectra. | 0 | Theoretical and Fundamental Chemistry |
Low plasticity burnishing (LPB) is a method of metal improvement that provides deep, stable surface compressive residual stresses with little cold work for improved damage tolerance and metal fatigue life extension. Improved fretting fatigue and stress corrosion performance has been documented, even at elevated temperatures where the compression from other metal improvement processes relax. The resulting deep layer of compressive residual stress has also been shown to improve high cycle fatigue (HCF) and low cycle fatigue (LCF) performance. | 1 | Applied and Interdisciplinary Chemistry |
For example, using the OSLOs for ferrocene shows great consistency with the prediction. The metal center was assigned the oxidation state of +2, and the Cp ligands were assigned the oxidation state of -1, which is quite consistent with the aromatic behavior of Cp. Furthermore, the last FOLI for ferrocene is 1.313 and the Δ-FOLI is 1.800, both indicating the unambiguity of the result.
However, for some complicated species possessing noninnocent ligands, the results become ambiguous. For example, several copper-trifluoromethyl complexes show small Δ-FOLI, which means the result is no longer unique. Moreover, whether the copper has the oxidation state of +3 or +1 remain controversial. Besides, for the Grubbs catalyst, the result is also inconsistent with conventional Fischer and Schrock classifications. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, bifunctionality or difunctionality is the presence of two functional groups in a molecule. A bifunctional species has the properties of each of the two types of functional groups, such as an alcohol (), amide (), aldehyde (), nitrile () or carboxylic acid (). Many bifunctional species are used to produce complex materials. They participate in condensation polymerization like polyester and polyamide.
Polyfunctional species have more than two functional groups. Most biological compounds are polyfunctional. | 0 | Theoretical and Fundamental Chemistry |
*Williams-Miles History of Chemistry Collection at Harding University, established in 1992
*The Houdry process for catalytic cracking of crude petroleum into gasoline, developed by Eugene Houdry and the Sun Oil Company in the 1930s
*Kem-Tone Wall Finish, the first commercially successful water-based paint, introduced by Sherwin-Williams in 1941
*The Sohio process for production of acrylonitrile, developed by Sohio in 1957 and commercialized in 1960 | 1 | Applied and Interdisciplinary Chemistry |
In RHT jurisdictions, vehicles are typically configured as left hand drive (LHD), with the steering wheel on the left side of the passenger compartment. In LHT jurisdictions, the reverse is true as the right hand drive (RHD) configuration. In most jurisdictions, the position of the steering wheel is not regulated, or explicitly permitted to be anywhere. The drivers side, the side closer to the centre of the road, is sometimes called the offside, while the passenger side, the side closer to the side of the road, is sometimes called the nearside'.
Most windscreen wipers are preferentially designed to better clean the drivers side of the windscreen and thus have a longer wiper blade on the drivers side and wipe up from the passenger side to the driver's side. Thus on LHD configurations, they wipe up from right to left, viewed from inside the vehicle, and do the opposite on RHD vehicles.
Historically there was less consistency in the relationship of the position of the driver to the handedness of traffic. Most American cars produced before 1910 were RHD. In 1908 Henry Ford standardised the Model T as LHD in RHT America, arguing that with RHD and RHT, the passenger was obliged to "get out on the street side and walk around the car" and that with steering from the left, the driver "is able to see even the wheels of the other car and easily avoids danger." By 1915 other manufacturers followed Ford's lead, due to the popularity of the Model T.
In specialised cases, the driver will sit on the nearside, or curbside. Examples include:
*Where the driver needs a good view of the nearside, e.g. street sweepers, or vehicles driven along unstable road edges. Similarly in mountainous areas the driver may be seated opposite side so that they have a better view of the road edge which may fall away for very many metres into the valley below. Swiss Postbuses in mountainous areas are a well known example.
*Where it is more convenient for the driver to be on the nearside, e.g. delivery vehicles. The Grumman LLV postal delivery truck is widely used with RHD configurations in RHT North America. Some Unimogs are designed to switch between LHD and RHD to permit operators to work on the more convenient side of the truck.
Generally, the convention is to mount a motorcycle on the left, and kickstands are usually on the left which makes it more convenient to mount on the safer kerbside as is the case in LHT. Some jurisdictions prohibit fitting a sidecar to a motorcycle's offside.
In 2020, there were 160 LHD heavy goods vehicles in the UK involved in accidents (%) for a total of 3,175 accidents, killing 215 people (%) for a total of 4271.
It has been suggested that right-hand drive vehicles, and hence the left-hand traffic direction, are associated with greater safety. As most drivers are right-handed, the dominant right hand remains controlled on the steering wheel while the non-dominant left hand can manipulate gears. The right field of vision may also be more dominant, thereby permitting a superior view of oncoming traffic. | 0 | Theoretical and Fundamental Chemistry |
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