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The latest technology being deployed at ports uses pressurized natural helium to directly detect fast neutrons, without the need for bulky neutron moderators. Utilizing recoil nuclei following neutron scatter events, natural helium glows (scintillates), allowing photomultipliers (e.g. SiPMs) to produce an electrical signal. Introducing moderators and lithium-6 to capture thermalized neutrons further increases the detection capabilities of natural helium, at the expense of losing the initial information of the neutrons (such as energy) and reducing sensitivity to shielded neutron-emitting materials. | 0 | Theoretical and Fundamental Chemistry |
Protein–lipid interaction is the influence of membrane proteins on the lipid physical state or vice versa.
The questions which are relevant to understanding of the structure and function of the membrane are: 1) Do intrinsic membrane proteins bind tightly to lipids (see annular lipid shell), and what is the nature of the layer of lipids adjacent to the protein? 2) Do membrane proteins have long-range effects on the order or dynamics of membrane lipids? 3) How do the lipids influence the structure and/or function of membrane proteins? 4) How do peripheral membrane proteins which bind to the layer surface interact with lipids and influence their behavior? | 1 | Applied and Interdisciplinary Chemistry |
In the German/US HIBALL study, Garching used the high repetition rate of the RF driver to serve four reactor chambers using liquid lithium inside the chamber cavity. In 1982 high-confinement mode (H-mode) was discovered in tokamaks. | 0 | Theoretical and Fundamental Chemistry |
Although not as toxic as many similar compounds, inhaled or ingested 1,1,1-trichloroethane does act as a central nervous system depressant and can cause effects similar to those of ethanol intoxication, including dizziness, confusion, and, in sufficiently high concentrations, unconsciousness and death. Fatal poisonings and illnesses linked to intentional inhalation of trichloroethane have been reported. The removal of the chemical from correction fluid commenced due to Proposition 65 declaring it hazardous and toxic.
Prolonged skin contact with the liquid can result in the removal of fats from the skin, resulting in skin irritation.
The International Agency for Research on Cancer places 1,1,1-trichloroethane in Group 2A as a probable carcinogen. | 1 | Applied and Interdisciplinary Chemistry |
With single or prolonged exposure by inhalation the lungs may become sensitized to beryllium. Berylliosis has a slow onset and progression. Some people who are sensitized to beryllium may not have symptoms. Continued exposure causes the development of small inflammatory nodules, called granulomas. Of note, the authors of a 2006 study suggested that beryllium inhalation was not the only form of exposure and perhaps skin exposure was also a cause, as they found that a reduction in beryllium inhalation did not result in a reduction in chronic beryllium disease or beryllium sensitization.
Granuloma formation is seen in other diseases such as tuberculosis and sarcoidosis. Sarcoidosis, like berylliosis, also produces granulomas without a necrotic core, and so distinction between the two processes can be difficult.
Ultimately, this process leads to restrictive lung disease (a decrease in diffusion capacity).
The earliest symptoms are typically cough and shortness of breath. Other symptoms include chest pain, joint aches, weight loss, and fever.
Rarely, one can get granulomas in other organs including the liver.
The onset of symptoms can range from weeks up to tens of years from the initial exposure. In some individuals, a single exposure to beryllium can cause berylliosis. | 1 | Applied and Interdisciplinary Chemistry |
The Goldich dissolution series follows the same pattern of the Bowen's reaction series, with the minerals that are first to crystallize also the first the undergo chemical weathering. The Bowen’s reaction series dictates that during fractional crystallization, olivine and Ca-plagioclase feldspars are the first to crystalize out of a melt, after which follows pyroxene, amphibole, biotite, Na-plagioglase, orthoclase feldspar, muscovite, and finally, quartz. This order is controlled by the temperature of the melt and its composition. Because earlier crystallizing minerals are more stable at higher temperatures and pressures, these weather the fastest under surface conditions. | 0 | Theoretical and Fundamental Chemistry |
Episomes in prokaryotes are special sequences which can divide either separate from or integrated into the prokaryotic chromosome. | 1 | Applied and Interdisciplinary Chemistry |
The immunomodulatory proteins, including virokines, in the poxvirus family have been extensively studied in the context of the evolution of the family. Virokines in this family are thought to have been acquired from host genes and from other viruses through horizontal gene transfer. Similar observations have been made in the herpesvirus family; for example, Epstein-Barr virus encodes an interleukin protein with high sequence identity to the human interleukin-10, suggesting a recent evolutionary origin. | 1 | Applied and Interdisciplinary Chemistry |
A hybridization assay comprises any form of quantifiable hybridization i.e. the quantitative annealing of two complementary strands of nucleic acids, known as nucleic acid hybridization. | 1 | Applied and Interdisciplinary Chemistry |
Dry cask storage typically involves taking waste from a spent fuel pool and sealing it (along with an inert gas) in a steel cylinder, which is placed in a concrete cylinder which acts as a radiation shield. It is a relatively inexpensive method which can be done at a central facility or adjacent to the source reactor. The waste can be easily retrieved for reprocessing. | 0 | Theoretical and Fundamental Chemistry |
Bifurcation theory is a useful way to study the stability of a given flow, with the changes that occur in the structure of a given system. Hydrodynamic stability is a series of differential equations and their solutions. A bifurcation occurs when a small change in the parameters of the system causes a qualitative change in its behavior,. The parameter that is being changed in the case of hydrodynamic stability is the Reynolds number. It can be shown that the occurrence of bifurcations falls in line with the occurrence of instabilities. | 1 | Applied and Interdisciplinary Chemistry |
In the thermodynamic limit, the total number of particles N are so large that the quantum number n may be treated as a continuous variable. In this case, the overall number density profile in the box is indeed uniform.
The number of quantum states in the range is:
Without loss of generality, the zero-point energy is chosen to be zero, with the following result:
Therefore, in the range:
the number of quantum states is:
Here, the degree of degeneracy is:
And the density of states is:
In modern literature, the above is sometimes also called the "density of states". However, differs from by a factor of the system's volume (which is in this 1D case).
Based on the following formula:
the Fermi energy in the thermodynamic limit can be calculated to be: | 0 | Theoretical and Fundamental Chemistry |
* [http://news.bbc.co.uk/2/hi/science/nature/3917539.stm Freak waves spotted from space], BBC News Online
* [http://www.esa.int/esaCP/SEMOKQL26WD_index_0.html Ship-sinking monster waves revealed by ESA satellites]
* [https://web.archive.org/web/20110719032700/http://coast.gkss.de/projects/maxwave/ MaxWave project]
* [https://web.archive.org/web/20070107055941/http://icms.org.uk/archive/meetings/2005/roguewaves/index.html Rogue Wave Workshop (2005)]
* [http://www.ifremer.fr/web-com/stw2004/rw/index.html Rogue Waves 2004] | 1 | Applied and Interdisciplinary Chemistry |
The European Journal of Inorganic Chemistry is a weekly peer-reviewed scientific journal covering inorganic, organometallic, bioinorganic, and solid-state chemistry. It is published by Wiley-VCH on behalf of Chemistry Europe.
The journal, along with the European Journal of Organic Chemistry, was established in 1998 as the result of a merger of Chemische Berichte/Recueil, Bulletin de la Société Chimique de France, Bulletin des Sociétés Chimiques Belges, Gazzetta Chimica Italiana, Anales de Química, Chimika Chronika, Revista Portuguesa de Química, and ACH-Models in Chemistry.
According to the Journal Citation Reports, the journal has a 2021 impact factor of 2.551. | 0 | Theoretical and Fundamental Chemistry |
Precipitation of minerals is affected by water solubility within silicate melts, which typically exists as hydroxyl groups bound to Si or Group 1 and Group 2 cations in concentrations ranging from approximately 6-7 wt. %. Specifically, the equilibrium of water and dissolved oxygen yields hydroxides, where the K has been approximated between 0.1 and 0.3.
This inherent solubility is low yet varies greatly depending on the pressure of the system. Rhyolitic magmas have the highest solubility, ranging from approximately 0% at the surface to nearly 10% at 1100 °C and 5 kbar. Degassing occurs when hydrous magma is uplifted, gradually converting the dissolved water to aqueous phase. This aqueous phase is typically abundant in volatiles, metals (copper, lead, zinc, silver and gold), and Group 1 and Group 2 cations. Dependent on which cation the hydroxyl is bound to, it significantly impacts the properties of a volcanic eruption, particularly its explosiveness. During unusually high temperature and pressure conditions exceeding 374 °C and 218 bar, water enters a supercritical fluid state and becomes no longer a liquid or a gas. | 0 | Theoretical and Fundamental Chemistry |
Synthetic elements are excluded from the classification, as they do not occur naturally.
Trace radioactive elements (namely Tc, Pm, Po, At, Rn, Fr, Ra, Ac, Pa, Np, Pu) are also treated as synthetic. Although these do occur in nature, their occurrence is entirely dependent on their long-lived parents Th and U, and they are not very mobile. For instance, polonium's chemistry would predict it to be a chalcophile, but it tends to occur instead as a lithophile along with its parent uranium. Even radon, which is a gas, does not usually have time to travel very far from the original uranium source before decaying. When needed, these elements are typically produced synthetically in nuclear reactors instead of using the tedious and laborious process of extraction from uranium ores. | 0 | Theoretical and Fundamental Chemistry |
* The Wildfowl and Wetlands Trust's London Wetland Centre includes a rain garden.
* Islington London Borough Council commissioned sustainable drainage consultants Robert Bray Associates to design a pilot rain garden in the Ashby Grove development which was completed in 2011. This raingarden is fed from a typical modest domestic roof catchment area of 30m² and is designed to demonstrate how simple and cost effective domestic rain gardens are to install. Monitoring apparatus was built into the design to allow Middlesex University to monitor water volumes, water quality, and soil moisture content. The rain garden basin is 300mm deep and has a storage capacity of 2.17m³ which is just over the volume required to store runoff from the roof catchment in a 1 in 100 storm plus 30% allowance for climate change.
* The Day Brook Rain Garden Project has introduced a number of rain gardens into an existing residential street in Sherwood, Nottingham | 1 | Applied and Interdisciplinary Chemistry |
Individual lengths of ductile iron pipe are joined either by flanges, couplings, or some form of spigot and socket arrangement. | 1 | Applied and Interdisciplinary Chemistry |
In the first step of the mechanism, the glycosyl bromide reacts with silver carbonate upon elimination of silver bromide and the silver carbonate anion to the oxocarbenium ion. From this structure a dioxolanium ring is formed, which is attacked by methanol via an mechanism at the carbonyl carbon atom. This attack leads to the inversion. After deprotonation of the intermediate oxonium, the product glycoside is formed.
The reaction can also be applied to carbohydrates with other protecting groups. In the oligosaccharide synthesis in place of the methanol other carbohydrates are used, which have been modified with protective groups in such a way that only one hydroxyl group is accessible. | 0 | Theoretical and Fundamental Chemistry |
The Navier–Stokes equations ( ) are partial differential equations which describe the motion of viscous fluid substances. They were named after French engineer and physicist Claude-Louis Navier and the Irish physicist and mathematician George Gabriel Stokes. They were developed over several decades of progressively building the theories, from 1822 (Navier) to 1842–1850 (Stokes).
The Navier–Stokes equations mathematically express momentum balance for Newtonian fluids and making use of conservation of mass. They are sometimes accompanied by an equation of state relating pressure, temperature and density. They arise from applying Isaac Newtons second law to fluid motion, together with the assumption that the stress in the fluid is the sum of a diffusing viscous term (proportional to the gradient of velocity) and a pressure term—hence describing viscous flow'. The difference between them and the closely related Euler equations is that Navier–Stokes equations take viscosity into account while the Euler equations model only inviscid flow. As a result, the Navier–Stokes are a parabolic equation and therefore have better analytic properties, at the expense of having less mathematical structure (e.g. they are never completely integrable).
The Navier–Stokes equations are useful because they describe the physics of many phenomena of scientific and engineering interest. They may be used to model the weather, ocean currents, water flow in a pipe and air flow around a wing. The Navier–Stokes equations, in their full and simplified forms, help with the design of aircraft and cars, the study of blood flow, the design of power stations, the analysis of pollution, and many other problems. Coupled with Maxwell's equations, they can be used to model and study magnetohydrodynamics.
The Navier–Stokes equations are also of great interest in a purely mathematical sense. Despite their wide range of practical uses, it has not yet been proven whether smooth solutions always exist in three dimensions—i.e., whether they are infinitely differentiable (or even just bounded) at all points in the domain. This is called the Navier–Stokes existence and smoothness problem. The Clay Mathematics Institute has called this one of the seven most important open problems in mathematics and has offered a US$1 million prize for a solution or a counterexample. | 1 | Applied and Interdisciplinary Chemistry |
Trimedoxime bromide (INN), also known as dipyroxime or TMB-4, is an oxime used in the treatment of organophosphate poisoning It is chemically related to asoxime pralidoxime and obidoxime. | 1 | Applied and Interdisciplinary Chemistry |
Bacteriorhodopsin belongs to the microbial rhodopsin family. Its homologs include the archaerhodopsins, the light-driven chloride pump halorhodopsin (for which the crystal structure is also known), and some directly light-activated channels such as channelrhodopsin.
Bacteriorhodopsin is similar to vertebrate rhodopsins, the pigments that sense light in the retina. Rhodopsins also contain retinal; however, the functions of rhodopsin and bacteriorhodopsin are different, and there is limited similarity in their amino acid sequences. Both rhodopsin and bacteriorhodopsin belong to the 7TM receptor family of proteins, but rhodopsin is a G protein-coupled receptor and bacteriorhodopsin is not. In the first use of electron crystallography to obtain an atomic-level protein structure, the structure of bacteriorhodopsin was resolved in 1990. It was then used as a template to build models of G protein-coupled receptors before crystallographic structures were also available for these proteins. It has been excessively studied on both mica and glass substrates using Atomic force microscopy and Femtosecond crystallography.
All other phototrophic systems in bacteria, algae, and plants use chlorophylls or bacteriochlorophylls rather than bacteriorhodopsin. These also produce a proton gradient, but in a quite different and more indirect way involving an electron transfer chain consisting of several other proteins. Furthermore, chlorophylls are aided in capturing light energy by other pigments known as "antennas"; these are not present in bacteriorhodopsin-based systems. It is possible that phototrophy independently evolved at least twice, once in bacteria and once in archaea. | 0 | Theoretical and Fundamental Chemistry |
The National Institute for Health and Care Excellence (NICE) in the UK, along with various non-governmental organizations focused on multiple sclerosis (MS), endorse the off-label use of modafinil to alleviate fatigue associated with MS.
MS-related fatigue is a common and often debilitating symptom experienced by people with multiple sclerosis. It can significantly impact their daily functioning, quality of life, and ability to perform everyday activities. When prescribed for MS-related fatigue management, modafinil works by promoting wakefulness and increasing alertness without causing drowsiness or disrupting nighttime sleep. People with multiple sclerosis often report increased energy levels, reduced feelings of tiredness, improved cognitive function, and an overall improvement in their quality of life when taking modafinil. While modafinil can provide relief from MS-related fatigue symptoms, it does not treat the underlying cause or cure MS itself. The primary goal of using modafinil in MS is symptom management and improving daily functioning. The effects of modafinil on other aspects of MS-related fatigue, such as severity and cognitive function, are less clear.
While modafinil has been shown to be effective in managing fatigue in people with MS, optimal dosing and treatment schedules are not well established. | 0 | Theoretical and Fundamental Chemistry |
Archimedes principle shows the buoyant force and displacement of fluid. However, the concept of Archimedes principle can be applied when considering why objects float. Proposition 5 of Archimedes treatise On Floating Bodies' states that
In other words, for an object floating on a liquid surface (like a boat) or floating submerged in a fluid (like a submarine in water or dirigible in air) the weight of the displaced liquid equals the weight of the object. Thus, only in the special case of floating does the buoyant force acting on an object equal the objects weight. Consider a 1-ton block of solid iron. As iron is nearly eight times as dense as water, it displaces only 1/8 ton of water when submerged, which is not enough to keep it afloat. Suppose the same iron block is reshaped into a bowl. It still weighs 1 ton, but when it is put in water, it displaces a greater volume of water than when it was a block. The deeper the iron bowl is immersed, the more water it displaces, and the greater the buoyant force acting on it. When the buoyant force equals 1 ton, it will sink no farther.
When any boat displaces a weight of water equal to its own weight, it floats. This is often called the "principle of flotation": A floating object displaces a weight of fluid equal to its own weight. Every ship, submarine, and dirigible must be designed to displace a weight of fluid at least equal to its own weight. A 10,000-ton ship's hull must be built wide enough, long enough and deep enough to displace 10,000 tons of water and still have some hull above the water to prevent it from sinking. It needs extra hull to fight waves that would otherwise fill it and, by increasing its mass, cause it to submerge. The same is true for vessels in air: a dirigible that weighs 100 tons needs to displace 100 tons of air. If it displaces more, it rises; if it displaces less, it falls. If the dirigible displaces exactly its weight, it hovers at a constant altitude.
While they are related to it, the principle of flotation and the concept that a submerged object displaces a volume of fluid equal to its own volume are not Archimedes principle. Archimedes principle, as stated above, equates the buoyant force to the weight of the fluid displaced.
One common point of confusion regarding Archimedes' principle is the meaning of displaced volume. Common demonstrations involve measuring the rise in water level when an object floats on the surface in order to calculate the displaced water. This measurement approach fails with a buoyant submerged object because the rise in the water level is directly related to the volume of the object and not the mass (except if the effective density of the object equals exactly the fluid density). | 1 | Applied and Interdisciplinary Chemistry |
In lone-pair-active multiferroics, the ferroelectric displacement is driven by the A-site cation, and the magnetism arises from a partially filled d shell on the B site. Examples include bismuth ferrite, BiFeO, BiMnO (although this is believed to be anti-polar), and PbVO. In these materials, the A-site cation (Bi, Pb) has a so-called stereochemically active 6s lone-pair of electrons, and off-centering of the A-site cation is favoured by an energy-lowering electron sharing between the formally empty A-site 6p orbitals and the filled O 2p orbitals. | 0 | Theoretical and Fundamental Chemistry |
This form factor does not include a display and these devices are designed to enable a new class of geographically-distributed spectrum monitoring and analysis applications. The key attribute is the ability to connect the analyzer to a network and monitor such devices across a network. While many spectrum analyzers have an Ethernet port for control, they typically lack efficient data transfer mechanisms and are too bulky or expensive to be deployed in such a distributed manner. Key applications for such devices include RF intrusion detection systems for secure facilities where wireless signaling is prohibited. As well cellular operators are using such analyzers to remotely monitor interference in licensed spectral bands. The distributed nature of such devices enable geo-location of transmitters, spectrum monitoring for dynamic spectrum access and many other such applications.
Key attributes of such devices include:
* Network-efficient data transfer
* Low power consumption
* The ability to synchronize data captures across a network of analyzers
* Low cost to enable mass deployment. | 0 | Theoretical and Fundamental Chemistry |
With regard to the theory of CVI and ESA, there was an important observation made by O'Brien, who linked these measured parameters with dynamic electrophoretic mobility μ.
where
: A is calibration constant, depending on frequency, but not particles properties;
: ρ is particle density,
: ρ density of the fluid,
: φ is volume fraction of dispersed phase,
Dynamic electrophoretic mobility is similar to electrophoretic mobility that appears in electrophoresis theory. They are identical at low frequencies and/or for sufficiently small particles.
There are several theories of the dynamic electrophoretic mobility. Their overview is given in the Ref.5. Two of them are the most important.
The first one corresponds to the Smoluchowski limit. It yields following simple expression for CVI for sufficiently small particles with negligible CVI frequency dependence:
where:
: ε is vacuum dielectric permittivity,
: ε is fluid dielectric permittivity,
: ζ is electrokinetic potential
: η is dynamic viscosity of the fluid,
: K is conductivity of the system,
: K is conductivity of the fluid,
: ρ is density of the system.
This remarkably simple equation has same wide range of applicability as Smoluchowski equation for electrophoresis. It is independent on shape of the particles, their concentration.
Validity of this equation is restricted with the following two requirements.
First, it is valid only for a thin double layer, when the Debye length is much smaller than particle's radius a:
Secondly, it neglects the contribution of the surface conductivity. This assumes a small Dukhin number:
Restriction of the thin double layer limits applicability of this Smoluchowski type theory only to aqueous systems with sufficiently large particles and not very low ionic strength. This theory does not work well for nano-colloids, including proteins and polymers at low ionic strength. It is not valid for low- or non-polar fluids.
There is another theory that is applicable for the other extreme case of a thick double layer, when
This theory takes into consideration the double layer overlap that inevitably occurs for concentrated systems with thick double layer. This allows introduction of so-called "quasi-homogeneous" approach, when overlapped diffuse layers of particles cover the complete interparticle space. The theory becomes much simplified in this extreme case, as shown by Shilov and others. Their derivation predicts that surface charge density σ is a better parameter than ζ-potential for characterizing electroacoustic phenomena in such systems. An expression for CVI simplified for small particles follows: | 0 | Theoretical and Fundamental Chemistry |
Fluoride can act as a base. It can combine with a proton ():
This neutralization reaction forms hydrogen fluoride (HF), the conjugate acid of fluoride.
In aqueous solution, fluoride has a pK value of 10.8. It is therefore a weak base, and tends to remain as the fluoride ion rather than generating a substantial amount of hydrogen fluoride. That is, the following equilibrium favours the left-hand side in water:
However, upon prolonged contact with moisture, soluble fluoride salts will decompose to their respective hydroxides or oxides, as the hydrogen fluoride escapes. Fluoride is distinct in this regard among the halides. The identity of the solvent can have a dramatic effect on the equilibrium shifting it to the right-hand side, greatly increasing the rate of decomposition. | 1 | Applied and Interdisciplinary Chemistry |
The beam origin concept is used to describe the mechanisms governing the ecological condition of running waters. It is based on the positive influence of sections in very good condition on sections in less good condition. The idea was first introduced in 2008 by the German Council for Land Stewardship to reach the goals defined in the Water Framework Directive of the European Union. | 1 | Applied and Interdisciplinary Chemistry |
People can be exposed to bitumen in the workplace by breathing in fumes or skin absorption. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit of 5 mg/m over a 15-minute period.
Bitumen is basically an inert material that must be heated or diluted to a point where it becomes workable for the production of materials for paving, roofing, and other applications. In examining the potential health hazards associated with bitumen, the International Agency for Research on Cancer (IARC) determined that it is the application parameters, predominantly temperature, that affect occupational exposure and the potential bioavailable carcinogenic hazard/risk of the bitumen emissions. In particular, temperatures greater than 199 °C (390 °F), were shown to produce a greater exposure risk than when bitumen was heated to lower temperatures, such as those typically used in asphalt pavement mix production and placement. IARC has classified paving asphalt fumes as a Class 2B possible carcinogen, indicating inadequate evidence of carcinogenicity in humans.
In 2020, scientists reported that bitumen currently is a significant and largely overlooked source of air pollution in urban areas, especially during hot and sunny periods.
A bitumen-like substance found in the Himalayas and known as shilajit is sometimes used as an Ayurveda medicine, but is not in fact a tar, resin or bitumen. | 0 | Theoretical and Fundamental Chemistry |
The surface-area-to-volume ratio has physical dimension inverse length (L) and is therefore expressed in units of inverse metre (m) or its prefixed unit multiples and submultiples. As an example, a cube with sides of length 1 cm will have a surface area of 6 cm and a volume of 1 cm. The surface to volume ratio for this cube is thus
For a given shape, SA:V is inversely proportional to size. A cube 2 cm on a side has a ratio of 3 cm, half that of a cube 1 cm on a side. Conversely, preserving SA:V as size increases requires changing to a less compact shape. | 0 | Theoretical and Fundamental Chemistry |
The OpenFOAM directory structure consists of two main directories:
* : OpenFOAM libraries whose directory layout is shown in the side-figure
* : A set of third-party libraries | 1 | Applied and Interdisciplinary Chemistry |
The most important (in a commercial sense) peroxides are produced by autoxidation, the direct reaction of with a hydrocarbon. Autoxidation is a radical reaction that begins with the abstraction of an H atom from a relatively weak C-H bond. Important compounds made in this way include tert-butyl hydroperoxide, cumene hydroperoxide and ethylbenzene hydroperoxide:
Auto-oxidation reaction is also observed with common ethers, such as diethyl ether, diisopropyl ether, tetrahydrofuran, and 1,4-dioxane. An illustrative product is diethyl ether peroxide. Such compounds can result in a serious explosion when distilled.
To minimize this problem, commercial samples of THF are often inhibited with butylated hydroxytoluene (BHT). Distillation of THF to dryness is avoided because the explosive peroxides concentrate in the residue.
Although ether hydroperoxide often form adventitiously (i.e. autoxidation), they can be prepared in high yield by the acid-catalyzed addition of hydrogen peroxide to vinyl ethers: | 0 | Theoretical and Fundamental Chemistry |
In the breakdown of a compound into its constituent parts, the generalized reaction for chemical decomposition is:
: AB → A + B (AB represents the reactant that begins the reaction, and A and B represent the products of the reaction)
An example is the electrolysis of water to the gases hydrogen and oxygen:
: 2 HO() → 2 H() + O() | 0 | Theoretical and Fundamental Chemistry |
Saloximes are used in the extraction and separation of metals from their ores. In one application of hydrometallurgy, Cu is extracted into organic solvents as its saloxime complex. | 0 | Theoretical and Fundamental Chemistry |
Depending on the position of an atom on a surface, it can be referred to by one of several names. Figure 1 illustrates the names for the atomic positions and point defects on a surface for a simple cubic lattice.
Figure 2 shows a scanning tunneling microscopy topographic image of a step edge that shows many of the features in Figure 1.<br>Figure 3 shows a crystal surface with steps, kinks, adatoms, and vacancies in a closely packed crystalline material, which resembles the surface featured in Figure 2. | 0 | Theoretical and Fundamental Chemistry |
An intuitive understanding of the phenomenon comes from Newton's third law, that the deflective force on the body is a reaction to the deflection that the body imposes on the air-flow. The body "pushes" the air in one direction, and the air pushes the body in the other direction. In particular, a lifting force is accompanied by a downward deflection of the air-flow. It is an angular deflection in the fluid flow, aft of the body.
Lyman Briggs made a wind tunnel study of the Magnus effect on baseballs, and others have produced images of the effect. The studies show that a turbulent wake behind the spinning ball causes aerodynamic drag, plus there is a noticeable angular deflection in the wake, and this deflection is in the direction of spin.
The process by which a turbulent wake develops aft of a body in an airflow is complex, but well-studied in aerodynamics. The thin boundary layer detaches itself ("flow separation") from the body at some point, and this is where the wake begins to develop. The boundary layer itself may be turbulent or not, and that has a significant effect on the wake formation. Quite small variations in the surface conditions of the body can influence the onset of wake formation and thereby have a marked effect on the downstream flow pattern. The influence of the body's rotation is of this kind.
It is said that Magnus himself wrongly postulated a theoretical effect with laminar flow due to skin friction and viscosity as the cause of the Magnus effect. Such effects are physically possible but slight in comparison to what is produced in the Magnus effect proper. In some circumstances the causes of the Magnus effect can produce a deflection opposite to that of the Magnus effect.
The diagram above shows lift being produced on a back-spinning ball. The wake and trailing air-flow have been deflected downwards. The boundary layer motion is more violent at the underside of the ball where the spinning movement of the balls surface is forward and reinforces the effect of the balls translational movement. The boundary layer generates wake turbulence after a short interval.
In baseball, this effect is used to generate the downward motion of a curveball, in which the baseball is rotating forward (with topspin). Participants in other sports played with a ball also take advantage of this effect.
On a cylinder, the force due to rotation is known as Kutta–Joukowski lift. It can be analysed in terms of the vortex produced by rotation. The lift on the cylinder per unit length, , is the product of the freestream velocity, (in m/s), the freestream density of the fluid, (in kg/m), and circulation of fluid established by the rotation, , due to viscous effects:
where the vortex strength (assuming that the surrounding fluid obeys the no-slip condition) is given by
where ω is the angular velocity of the cylinder (in rad/s) and r is the radius of the cylinder (in m). | 1 | Applied and Interdisciplinary Chemistry |
The area of temporary hypoxic bottom water that occurs most summers off the coast of Louisiana in the Gulf of Mexico is the largest recurring hypoxic zone in the United States. It occurs only during the summer months of the year due to summer warming, regional circulation, wind mixing and high freshwater discharge. The Mississippi River, which is the drainage area for 41% of the continental United States, dumps high-nutrient runoff such as nitrates and phosphorus into the Gulf of Mexico. According to a 2009 fact sheet created by NOAA, "seventy percent of nutrient loads that cause hypoxia are a result of this vast drainage basin". which includes the heart of U.S. agribusiness, the Midwest. The discharge of treated sewage from urban areas (pop. c 12 million in 2009) combined with agricultural runoff deliver c. 1.7 million tons of phosphorus and nitrogen into the Gulf of Mexico every year. Nitrogen is indeed needed to increase crop yields, but plants are inefficient at taking it up, and often more fertilizers are used than plants actually need. Therefore, only a percentage of applied nitrogen ends up in the crops; and in some areas that number is less than 20%. Even though Iowa occupies less than 5% of the Mississippi River drainage basin, average annual nitrate discharge from surface water in Iowa is about 204,000 to 222,000 metric tonnes, or 25% of all the nitrate which the Mississippi River delivers to the Gulf of Mexico. Export from the Raccoon River Watershed is among the highest in the United States with annual yields at 26.1 kg/ha/year which ranked as the highest loss of nitrate out of 42 Mississippi subwatersheds evaluated for a Gulf of Mexico hypoxia report. In 2012, Iowa introduced the Iowa Nutrient Reduction Strategy, which "is a science and technology-based framework to assess and reduce nutrients to Iowa waters and the Gulf of Mexico. It is designed to direct efforts to reduce nutrients in surface water from both point and nonpoint sources in a scientific, reasonable and cost effective manner." The strategy continues to evolve, using voluntary methods to reduce Iowas negative contributions through outreach, research, and implementation of nutrient holding practices. In order to help reduce agricultural runoff into the Mississippi Basin, Minnesota passed [https://www.revisor.mn.gov/statutes/cite/103F.48 MN Statute 103F.48] in 2015, also known as the "Buffer Law", which was designed to implement mandatory riparian buffers between farmland and public waterways across the State of Minnesota. The [http://bwsr.state.mn.us Minnesota Board of Water and Soil Resources] (BWSR) issued a January 2019 report stating that compliance with the Buffer Law' has reached 99%. | 0 | Theoretical and Fundamental Chemistry |
The contact angle (symbol ) is the angle between a liquid surface and a solid surface where they meet. More specifically, it is the angle between the surface tangent on the liquid–vapor interface and the tangent on the solid–liquid interface at their intersection.
It quantifies the wettability of a solid surface by a liquid via the Young equation.
A given system of solid, liquid, and vapor at a given temperature and pressure has a unique equilibrium contact angle. However, in practice a dynamic phenomenon of contact angle hysteresis is often observed, ranging from the advancing (maximal) contact angle to the receding (minimal) contact angle. The equilibrium contact is within those values, and can be calculated from them. The equilibrium contact angle reflects the relative strength of the liquid, solid, and vapour molecular interaction.
The contact angle depends upon the medium above the free surface of the liquid, and the nature of the liquid and solid in contact. It is independent of the inclination of solid to the liquid surface. It changes with surface tension and hence with the temperature and purity of the liquid. | 0 | Theoretical and Fundamental Chemistry |
Expansion joint failure can occur for various reasons, but experience shows that failures fall into several distinct categories. This list includes, but is not limited to: shipping and handling damage, improper installation/insufficient protection, during/after installation, improper anchoring, guiding, and supporting of the system, anchor failure in service, corrosion, system over-pressure, excessive bellows deflection, torsion, bellows erosion, and particulate matter in bellows convolutions restricting proper movement.
There are various actions that can be taken to prevent and minimize expansion joint failure. During installation, prevent any damage to the bellows by carefully following the instructions furnished by the manufacturer. After installation, carefully inspect the entire piping system to see if any damage occurred during installation, if the expansion joint is in the proper location, and if the expansion joint flow direction and positioning is correct. Also, periodically inspect the expansion joint throughout the operating life of the system in order to check for external corrosion, loosening of threaded fasteners and deterioration of anchors, guides, and other hardware. | 1 | Applied and Interdisciplinary Chemistry |
It gives the ratio of the occurrence each amino acid combination in the observed data to the expected value of occurrence of the pair.
It is rounded off and used in the substitution matrix.
where is the probability of observing the pair and is the expected probability of such a pair occurring, given the background probabilities of each amino acid. | 1 | Applied and Interdisciplinary Chemistry |
Kazzinc selected the copper ISASMELT process for its Ust-Kamenogorsk metallurgical complex. It is designed to treat 290,000 t/y of copper concentrate and was commissioned in 2011. A projected capital cost for the smelter and refinery in 2006 was US$178 million. | 1 | Applied and Interdisciplinary Chemistry |
Diffuse correlation spectrometry measures the motion of scatters or red blood cells in tissue by analyzing the intensity of autocorrelation functions.
There are many advantages to this method. The first advantage is that DCS can be used for patients of all ages. This is significant as some modalities such as MRI are difficult to use for certain populations. The second advantage is that DCS instrumentation is easy to assemble and requires only one wavelength that can be chosen. The third advantage is that the theoretical concepts of DCS can be adapted to other blood flow imaging techniques.
However, there are limitations associated with DCS. First, the reason for why the dynamics of RBCs are so well approximated by a Brownian motion flow model is still not clear. Second, motion artifacts are common and can generate signals that can mislead physiological interpretation. Third, on the instrumentation side, the low SNR levels due to small fibers and tissues are challenging.
Next steps for DCS include using this modality as a bedside monitor of cerebral perfusion. Furthermore, DCS should be used to increase our understanding of early brain development. The ability to monitor neurovascular responses will enable the use of more complex stimulation paradigms. | 0 | Theoretical and Fundamental Chemistry |
A group of distinguished scientists from the U.S. Department of Energy’s (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) did a recent study on how laminin-111 interacts with the cytoplasmic protein, actin. Their study gave the following conclusions:
The biological process in which a cell ceases to continue growing and dividing is called quiescence (the opposite of cancer). ECM laminin-111 sends chemical signals that promotes adhesion of a cell and its ECM. Although the mechanism is unknown, these signals have also been linked to cell quiescence. Adding laminin-111 to breast epithelial cells leads to quiescence by altering nuclear actin. High levels of laminin-111 deplete nuclear actin which induces quiescence of cells. However, when an isoform of actin, that cannot exit a cell’s nucleus, is active, cells continue to grow and divide even when laminin levels are high. ECM laminin-111 levels in a normal breast cell are significantly higher than laminin-111 levels in tissues of cancerous breast tissue. Simply increasing laminin levels in the ECM of cancerous breast cells is not enough to lead to quiescence. Therefore, it is implied that there are multiple factors working together influencing cell-to-cell communication. How laminin-111 and nuclear actin communicate is one of these factors. Laminin-111 could be the physiological regulator of nuclear actin which would suggest that depleting nuclear actin could be a key to achieving cell quiescence and returning to homeostatic operating conditions. Decreased expression of laminin-111 and the growth-inhibitory signals that it produces in malignant myoepithelial cells begs for further investigation with regard to cancer research. Therefore, further exploration of laminin-111 and nuclear actin interaction could be a target for future experimental therapeutic investigations. | 0 | Theoretical and Fundamental Chemistry |
The percent yield is a comparison between the actual yield—which is the weight of the intended product of a chemical reaction in a laboratory setting—and the theoretical yield—the measurement of pure intended isolated product, based on the chemical equation of a flawless chemical reaction, and is defined as,
The ideal relationship between products and reactants in a chemical reaction can be obtained by using a chemical reaction equation. Stoichiometry is used to run calculations about chemical reactions, for example, the stoichiometric mole ratio between reactants and products. The stoichiometry of a chemical reaction is based on chemical formulas and equations that provide the quantitative relation between the number of moles of various products and reactants, including yields. Stoichiometric equations are used to determine the limiting reagent or reactant—the reactant that is completely consumed in a reaction. The limiting reagent determines the theoretical yield—the relative quantity of moles of reactants and the product formed in a chemical reaction. Other reactants are said to be present in excess. The actual yield—the quantity physically obtained from a chemical reaction conducted in a laboratory—is often less than the theoretical yield. The theoretical yield is what would be obtained if all of the limiting reagent reacted to give the product in question. A more accurate yield is measured based on how much product was actually produced versus how much could be produced. The ratio of the theoretical yield and the actual yield results in a percent yield.
When more than one reactant participates in a reaction, the yield is usually calculated based on the amount of the limiting reactant, whose amount is less than stoichiometrically equivalent (or just equivalent) to the amounts of all other reactants present. Other reagents present in amounts greater than required to react with all the limiting reagent present are considered excess. As a result, the yield should not be automatically taken as a measure for reaction efficiency.
In their 1992 publication General Chemistry, Whitten, Gailey, and Davis described the theoretical yield as the amount predicted by a stoichiometric calculation based on the number of moles of all reactants present. This calculation assumes that only one reaction occurs and that the limiting reactant reacts completely.
According to Whitten, the actual yield is always smaller (the percent yield is less than 100%), often very much so, for several reasons. As a result, many reactions are incomplete and the reactants are not completely converted to products. If a reverse reaction occurs, the final state contains both reactants and products in a state of chemical equilibrium. Two or more reactions may occur simultaneously, so that some reactant is converted to undesired side products. Losses occur in the separation and purification of the desired product from the reaction mixture. Impurities are present in the starting material which do not react to give desired product. | 0 | Theoretical and Fundamental Chemistry |
The other types of algae are diatoms and dinoflagellates, found primarily in marine environments, such as ocean coastlines or bays, where they can also form algal blooms. Coastal HABs are a natural phenomenon, although in many instances, particularly when they form close to coastlines or in estuaries, it has been shown that they are exacerbated by human-induced eutrophication and/or climate change. They can occur when warmer water, salinity, and nutrients reach certain levels, which then stimulates their growth. Most HAB algae are dinoflagellates. They are visible in water at a concentration of 1,000 algae cells/ml, while in dense blooms they can measure over 200,000/ml.
Diatoms produce domoic acid, another neurotoxin, which can cause seizures in higher vertebrates and birds as it concentrates up the food chain. Domoic acid readily accumulates in the bodies of shellfish, sardines, and anchovies, which if then eaten by sea lions, otters, cetaceans, birds or people, can affect the nervous system causing serious injury or death. In the summer of 2015, the state governments closed important shellfish fisheries in Washington, Oregon and California because of high concentrations of domoic acid in shellfish.
In the marine environment, single-celled, microscopic, plant-like organisms naturally occur in the well-lit surface layer of any body of water. These organisms, referred to as phytoplankton or microalgae, form the base of the food web upon which nearly all other marine organisms depend. Of the 5000+ species of marine phytoplankton that exist worldwide, about 2% are known to be harmful or toxic. Blooms of harmful algae can have large and varied impacts on marine ecosystems, depending on the species involved, the environment where they are found, and the mechanism by which they exert negative effects. | 0 | Theoretical and Fundamental Chemistry |
When dealing with a heterogeneous surface, the Wenzel model is not sufficient. A more complex model is needed to measure how the apparent contact angle changes when various materials are involved. This heterogeneous surface, like that seen in Figure 8, is explained using the Cassie–Baxter equation (Cassie's law):
Here the r is the roughness ratio of the wet surface area and f is the fraction of solid surface area wet by the liquid. It is important to realize that when f = 1 and r = r, the Cassie–Baxter equations becomes the Wenzel equation. On the other hand, when there are many different fractions of surface roughness, each fraction of the total surface area is denoted by .
A summation of all equals 1 or the total surface. Cassie–Baxter can also be recast in the following equation:
Here is the Cassie–Baxter surface tension between liquid and vapor, is the solid vapor surface tension of every component, and is the solid liquid surface tension of every component. A case that is worth mentioning is when the liquid drop is placed on the substrate and creates small air pockets underneath it. This case for a two-component system is denoted by:
Here the key difference to notice is that there is no surface tension between the solid and the vapor for the second surface tension component. This is because of the assumption that the surface of air that is exposed is under the droplet and is the only other substrate in the system. Subsequently, the equation is then expressed as (1 – f). Therefore, the Cassie equation can be easily derived from the Cassie–Baxter equation. Experimental results regarding the surface properties of Wenzel versus Cassie–Baxter systems showed the effect of pinning for a Young angle of 180 to 90°, a region classified under the Cassie–Baxter model. This liquid/air composite system is largely hydrophobic. After that point, a sharp transition to the Wenzel regime was found where the drop wets the surface, but no further than the edges of the drop. Actually, the Young, Wenzel and Cassie-Baxter equations represent the transversality conditions of the variational problem of wetting. | 0 | Theoretical and Fundamental Chemistry |
Beryllides of cobalt and nickel have metallurgical importance as the precipitated phase in beryllium copper alloys. These materials are nonsparking, which allows them to be used in certain hazardous environments.
In nuclear technology, beryllides are investigated as neutron multipliers. Unlike metallic Be, materials such as BeTi are more resistant to oxidation by water but retain the neutron-multiplying properties of the predominant isotope Be. | 1 | Applied and Interdisciplinary Chemistry |
Suspension array technology (or SAT) is a high throughput, large-scale, and multiplexed screening platform used in molecular biology. SAT has been widely applied to genomic and proteomic research, such as single nucleotide polymorphism (SNP) genotyping, genetic disease screening, gene expression profiling, screening drug discovery and clinical diagnosis. SAT uses microsphere beads (5.6 um in diameter) to prepare arrays. SAT allows for the simultaneous testing of multiple gene variants through the use of these microsphere beads as each type of microsphere bead has a unique identification based on variations in optical properties, most common is fluorescent colour. As each colour and intensity of colour has a unique wavelength, beads can easily be differentiated based on their wavelength intensity. Microspheres are readily suspendable in solution and exhibit favorable kinetics during an assay. Similar to flat microarrays (e.g. DNA microarray), an appropriate receptor molecule, such as DNA oligonucleotide probes, antibodies, or other proteins, attach themselves to the differently labeled microspheres. This produces thousands of microsphere array elements. Probe-target hybridization is usually detected by optically labeled targets, which determines the relative abundance of each target in the sample. | 1 | Applied and Interdisciplinary Chemistry |
Symbols for chemical elements shall be written in roman (upright) type. The symbol is not followed by a full-stop.
Examples:
: H He C Ca
Attached subscripts or superscripts specifying a nucleotide or molecule have the following meanings and positions:
* The nucleon number (mass number) is shown in the left superscript position (e.g., N)
* The number of atoms of a nucleotide is shown in the right subscript position (e.g., N)
* The proton number (atomic number) may be indicated in the left subscript position (e.g., Gd)
* If necessary, a state of ionization or an excited state may be indicated in the right superscript position (e.g., state of ionization Na) | 0 | Theoretical and Fundamental Chemistry |
The study of agrominerals is termed agrogeology, and agrogeologists are concerned with issues such as the replenishment of soil fertility in areas where agrominerals have been depleted by unsustainable farming methods. With current farming practice, the system is expected to have high crop production with low soil quality. Over time with this type of practice, ground nutrients have been depleted which has led to an increase in chemical fertilizer usage. Chemical fertilizers have been shown to have runoff and it can contaminate groundwaters and are not economically feasible for third world countries. One of the major sources for chemical fertilizers is potash ore. The other concern with the potash ore is the supply is finite and is running out, hence the increase in pricing. Potash is one of the major sources for potassium and phosphorus and one of the original agrominerals. Finding alternative sources for these agrominerals was a concept that was created to focus on soil remediation, to increase productivity in a low-cost manner.
At first agrominerals were used to help recreate soil conditions for exotic plants. These were simple practices that occur on a much smaller scale. These include using perlite to enhance the aeration of the soil, using pumice to control evaporation while one can use vermiculites and zeolites to store moisture. This soil modification was the start of the agromineral concept and has evolved into looking for alternative sources to obtain the three major nutrient elements. Remineralization has been the term created for implementing rock powders into soils as a source of nutrients. This process has been implemented into bigger operations and has found great success in places like Brazil, Germany, Norway, South Africa, Sri Lanka, and Uganda. | 0 | Theoretical and Fundamental Chemistry |
There are many GFP-like proteins that, despite being in the same protein family as GFP, are not directly derived from Aequorea victoria. These include dsRed, eqFP611, Dronpa, TagRFPs, KFP, EosFP/IrisFP, Dendra, and so on. Having been developed from proteins in different organisms, these proteins can sometimes display unanticipated approaches to chromophore formation. Some of these, such as KFP, are developed from naturally non- or weakly-fluorescent proteins to be greatly improved upon by mutagenesis. When GFP-like barrels of different spectra characteristics are used, the excitation spectra of one chromophore can be used to power another chromophore (FRET), allowing for conversion between wavelengths of light.
FMN-binding fluorescent proteins (FbFPs) were developed in 2007 and are a class of small (11–16 kDa), oxygen-independent fluorescent proteins that are derived from blue-light receptors. They are intended especially for the use under anaerobic or hypoxic conditions, since the formation and binding of the Flavin chromophore does not require molecular oxygen, as it is the case with the synthesis of the GFP chromophore.
Fluorescent proteins with other chromophores, such as UnaG with bilirubin, can display unique properties like red-shifted emission above 600 nm or photoconversion from a green-emitting state to a red-emitting state. They can have excitation and emission wavelengths far enough apart to achieve conversion between red and green light.
A new class of fluorescent protein was evolved from a cyanobacterial (Trichodesmium erythraeum) phycobiliprotein, α-allophycocyanin, and named small ultra red fluorescent protein (smURFP) in 2016. smURFP autocatalytically self-incorporates the chromophore biliverdin without the need of an external protein, known as a lyase. Jellyfish- and coral-derived GFP-like proteins require oxygen and produce a stoichiometric amount of hydrogen peroxide upon chromophore formation. smURFP does not require oxygen or produce hydrogen peroxide and uses the chromophore, biliverdin. smURFP has a large extinction coefficient (180,000 M cm) and has a modest quantum yield (0.20), which makes it comparable biophysical brightness to eGFP and ~2-fold brighter than most red or far-red fluorescent proteins derived from coral. smURFP spectral properties are similar to the organic dye Cy5.
Reviews on new classes of fluorescent proteins and applications can be found in the cited reviews. | 1 | Applied and Interdisciplinary Chemistry |
When a molecule of chlorophyll absorbs light it is promoted from its ground state to its first singlet excited state. The excited state then has three main fates. Either the energy is; 1. passed to another chlorophyll molecule by Förster resonance energy transfer (in this way excitation is gradually passed to the photochemical reaction centers (photosystem I and photosystem II) where energy is used in photosynthesis (called photochemical quenching)); or 2. the excited state can return to the ground state by emitting the energy as heat (called non-photochemical quenching); or 3. the excited state can return to the ground state by emitting a photon (fluorescence).
In higher plants, the absorption of light continues to increase as light intensity increases, while the capacity for photosynthesis tends to saturate. Therefore, there is the potential for the absorption of excess light energy by photosynthetic light harvesting systems. This excess excitation energy leads to an increase in the lifetime of singlet excited chlorophyll, increasing the chances of the formation of long-lived chlorophyll triplet states by inter-system crossing. Triplet chlorophyll is a potent photosensitiser of molecular oxygen forming singlet oxygen which can cause oxidative damage to the pigments, lipids and proteins of the photosynthetic thylakoid membrane. To counter this problem, one photoprotective mechanism is so-called non-photochemical quenching (NPQ), which relies upon the conversion and dissipation of the excess excitation energy into heat. NPQ involves conformational changes within the light harvesting proteins of photosystem (PS) II that bring about a change in pigment interactions causing the formation of energy traps. The conformational changes are stimulated by a combination of transmembrane proton gradient, the photosystem II subunit S (PsBs) and the enzymatic conversion of the carotenoid violaxanthin to zeaxanthin (the xanthophyll cycle).
Violaxanthin is a carotenoid downstream from chlorophyll a and b within the antenna of PS II and nearest to the special chlorophyll a located in the reaction center of the antenna. As light intensity increases, acidification of the thylakoid lumen takes place through the stimulation of carbonic anhydrase, which in turn converts bicarbonate (HCO) into carbon dioxide causing an influx of CO and inhibiting Rubisco oxygenase activity. This acidification also leads to the protonation of the PsBs subunit of PS II which catalyze the conversion of violaxanthin to zeaxanthin, and is involved in the alteration orientation of the photosystems at times of high light absorption to reduce the quantities of carbon dioxide created and start the non-photochemical quenching, along with the activation of enzyme violaxanthin de-epoxidase which eliminates an epoxide and forms an alkene on a six-member ring of violaxanthin giving rise to another carotenoid known as antheraxanthin. Violaxanthin contains two epoxides each bonded to a six-member ring and when both are eliminated by de-epoxidase the carotenoid zeaxanthin is formed. Only violaxanthin is able to transport a photon to the special chlorophyll a. Antheraxanthin and zeaxanthin dissipate the energy from the photon as heat preserving the integrity of photosystem II. This dissipation of energy as heat is one form of non-photochemical quenching. | 0 | Theoretical and Fundamental Chemistry |
Hydrosilylation of alkenes represents a commercially important method for preparing organosilicon compounds. The process is mechanistically similar to the hydrogenation of alkenes. In fact, similar catalysts are sometimes employed for the two catalytic processes.
The prevalent mechanism, called the Chalk-Harrod mechanism, assumes an intermediate metal complex that contains a hydride, a silyl ligand (RSi), and the alkene substrate. Oxidative addition proceeds by the intermediacy of a sigma-complex, wherein the Si-H bond is not fully broken.
Hydrosilylation of alkenes usually proceeds via anti-Markovnikov addition, i.e., silicon is placed at the terminal carbon when hydrosilylating a terminal alkene Variations of the Chalk-Harrod mechanism exist. Some cases involve insertion of alkene into M-Si bond followed by reductive elimination, the opposite of the sequence in the Chalk-Harrod mechanism. In certain cases, hydrosilylation results in vinyl or allylic silanes resulting from beta-hydride elimination.
Alkynes also undergo hydrosilylation, e.g., the addition of triethylsilane to diphenylacetylene:
:EtSiH + PhC≡CPh → EtSi(Ph)C=CH(Ph) | 0 | Theoretical and Fundamental Chemistry |
DNA‐templated organic synthesis (DTS) is a way to control the reactivity of synthetic molecules by using nature's molarity‐based approach. Historically, DTS was used as a model of prebiotic nucleic acid replication. Now however, it is capable of translating DNA sequences into complex small‐molecule and polymer products of multistep organic synthesis. | 1 | Applied and Interdisciplinary Chemistry |
The diastereoselectivity of radical cyclizations is often high. In most all-carbon cases, selectivity can be rationalized according to Beckwiths guidelines, which invoke the reactant-like, exo transition state shown above. Placing substituents in pseudoequatorial positions in the transition state leads to cis products from simple secondary radicals. Introducing polar substituents can favor trans' products due to steric or electronic repulsion between the polar groups. In more complex systems, the development of transition state models requires consideration of factors such as allylic strain and boat-like transition states
Chiral auxiliaries have been used in enantioselective radical cyclizations with limited success. Small energy differences between early transition states constitute a profound barrier to success in this arena. In the example shown, diastereoselectivity (for both configurations of the left-hand stereocenter) is low and enantioselectivity is only moderate.
Substrates with stereocenters between the radical and multiple bond are often highly stereoselective. Radical cyclizations to form polycyclic products often take advantage of this property. | 0 | Theoretical and Fundamental Chemistry |
Peripherally selective trans-3,4-dimethyl-4-(3-hydroxylphenyl)piperidine opioid antagonists were developed for the treatment of gastrointestinal motility disorder by Zimmerman and his coworkers. From that, they derived the 4-(3-hydroxyphenyl)-3,4-dimethylpiperidine scaffold with functional groups spanning various sizes, charge, and polarity to reach peripheral opioid receptor antagonism while decreasing CNS drug exposure. The in vitro μ-Ki, in vivo AD50, and ED50 and peripheral index (ratio) was examined for several selective analogs, and from that, they found out that the trans-3,4-dimethyl-4-(3-hydroxyphenyl) piperidine, Alvimopan, gave the best results. The large zwitterionic structure and the high polarity prevents Alvimopan from crossing the blood–brain barrier, potency at binding peripheral MORs is thereby 200 times that of central MORs. | 1 | Applied and Interdisciplinary Chemistry |
Roughness length () is a parameter of some vertical wind profile equations that model the horizontal mean wind speed near the ground. In the log wind profile, it is equivalent to the height at which the wind speed theoretically becomes zero in the absence of wind-slowing obstacles and under neutral conditions. In reality, the wind at this height no longer follows a mathematical logarithm. It is so named because it is typically related to the height of terrain roughness elements (i.e. protrusions from and/or depressions into the surface). For instance, forests tend to have much larger roughness lengths than tundra. The roughness length does not exactly correspond to any physical length. However, it can be considered as a length-scale representation of the roughness of the surface. | 1 | Applied and Interdisciplinary Chemistry |
Halohydrins are usually prepared by treatment of an alkene with a halogen, in the presence of water. The reaction is a form of electrophilic addition, with the halogen acting as electrophile. In that regard, it resembles the halogen addition reaction and proceeds with anti addition, leaving the newly added X and OH groups in a trans configuration. The chemical equation for the conversion of ethylene to ethylene chlorohydrin is:
:HC=CH + Cl + HO → H(OH)C-CHCl + HCl
When bromination is desired, N-bromosuccinimide (NBS) can be preferable to bromine because fewer side-products are produced. | 0 | Theoretical and Fundamental Chemistry |
The N-terminal telopeptide (NTX), also known as amino-terminal collagen crosslinks, is the N-terminal telopeptide of fibrillar collagens such as collagen type I and type II. It is used as a biomarker to measure the rate of bone turnover. NTX can be measured in the urine (uNTX) or serum (serum NTX). The peptide consists of eight amino acids with the sequence YDEKSTGG. | 1 | Applied and Interdisciplinary Chemistry |
It crystallizes as a tetrameric cubane-type cluster. It crystallises from tetrahydrofuran/pentane at −20°C as [tBuOK·tBuOH], which consists of straight chains linked by hydrogen bonding. Sublimation of [tBuOK·tBuOH] affords the tetramer [tBuOK], which adopts a cubane-like structure. Mild Lewis basic solvents such as THF and diethyl ether do not break up the tetrameric structure, which persists in the solid, in solution and even in the gas phase. | 0 | Theoretical and Fundamental Chemistry |
In 1860, aged 20, Cleve became assistant professor of mineralogy at the University of Uppsala, and was appointed assistant professor of chemistry in 1868. He also taught at the Royal Institute of Technology between 1870 and 1874, and eventually became professor of general and agricultural chemistry at the University of Uppsala. He was the chair of chemistry at the University of Uppsala starting in 1874. He was also the president of the Nobel Committee for Chemistry.
Cleves first work was Några ammoniakaliska chromföreningar (Some compounds of ammonia and chromium', 1861). He also wrote several more papers on complex compounds, including the compounds of platinum. Additionally, Cleve synthesized several hundred complex platinum compounds.
Cleve visited a number of laboratories in England, France, Italy, and Switzerland in the 1860s. While in Paris, he visited the laboratory of Charles-Adolphe Wurtz and also made a number of friends there.
Cleve worked on the synthesis of complex chemical compounds until 1872. He theorized in 1874 that the element didymium consisted of two elements. This theory was proven right with the discovery of praseodymium and neodymium in 1885 by Carl Auer von Welsbach. In 1879, Cleve proved that the newly discovered element scandium was an element predicted by Dmitri Mendeleev to be "eka-boron". He isolated a quantity of scandium in this same year and determined its atomic weight. He discovered the element holmium in 1879 by examining a sample of erbium oxide. While removing impurities from a sample of erbium oxide, Cleve discovered a brown substance and a green substance, and the brown substance was holmium oxide (the green substance was thulium oxide). However, this sample may have been impure. He separated thulium from an erbium oxide sample in 1879. Additionally, Cleve and Abraham Langlet discovered helium in the mineral cleveite in 1895.
Cleve discovered six forms of dichloronaphthalene and discovered aminonaphthalenesulfonic acids, which are sometimes named after him. He prepared a number of nitrosulfonic acids as well. In 1883, Cleve was the first person to describe the plankton species Nitzschia seriata. In 1890, Cleve began to mainly focus on the field of biology, mainly studying freshwater algae, diatoms, and plankton. Cleve participated in a Swedish expedition to Spitsbergen in 1898. While on this mission, he discovered a number of species of spumellarians, nassellarians, and phaeodarians.
Cleve, in collaboration with
Otto Höglund
prepared numerous previously-undiscovered salts of yttrium and erbium. The two also did work on the chemistry of the chemical elements thorium and lanthanum. By 1874, Cleve discovered that thorium was a quadrivalent element and also determined lanthanum to be trivalent. These findings were initially doubted by the scientific community.
Cleve was the first observer of isomerism in platinumamine derivatives.
Additionally, Cleve created a method of dating glacial and post-glacial deposits in the fossil record.
Cleves PhD dissertation was "Mineral-analytiska under-sökningar". He wrote a paper on samarium in 1879 and The Seasonal Distribution of Atlantic Plankton Organisms in 1900. In 1883, he published Kemiskt Handlexicon, which translates to Chemical Handbook'. Notable students of Cleve include Ellen Fries (the first Swedish woman to earn a PhD) and Svante Arrhenius (a winner of the Nobel Prize).
Cleve also studied hydrography and geology. | 1 | Applied and Interdisciplinary Chemistry |
Evidence for the role of the endocannabinoid system in food-seeking behavior comes from a variety of cannabinoid studies. Emerging data suggests that THC acts via CB receptors in the hypothalamic nuclei to directly increase appetite. It is thought that hypothalamic neurons tonically produce endocannabinoids that work to tightly regulate hunger. The amount of endocannabinoids produced is inversely correlated with the amount of leptin in the blood. For example, mice without leptin not only become massively obese but express abnormally high levels of hypothalamic endocannabinoids as a compensatory mechanism. Similarly, when these mice were treated with an endocannabinoid inverse agonists, such as rimonabant, food intake was reduced. When the CB receptor is knocked out in mice, these animals tend to be leaner and less hungry than wild-type mice. A related study examined the effect of THC on the hedonic (pleasure) value of food and found enhanced dopamine release in the nucleus accumbens and increased pleasure-related behavior after administration of a sucrose solution. A related study found that endocannabinoids affect taste perception in taste cells. In taste cells, endocannabinoids were shown to selectively enhance the strength of neural signaling for sweet tastes, whereas leptin decreased the strength of this same response. While there is need for more research, these results suggest that cannabinoid activity in the hypothalamus and nucleus accumbens is related to appetitive, food-seeking behavior. | 1 | Applied and Interdisciplinary Chemistry |
In November 2004 Rochdale councillor Tom Stott, a former employee at Turners, warned that any development of the site could be an environmental disaster, and that there could be so much asbestos waste in the ground that serious disturbance could lead to "Rochdales Chernobyl." He also expressed concern that the developers would be allowed by the council to carry out their own contamination survey to determine whether the site was fit for development, which was confirmed by the council: "Any developers would have to provide a full environmental assessment of the site as part of their planning application. The council wouldnt be doing any surveys of its own because it doesnt have the expertise or the resources to do this." | 1 | Applied and Interdisciplinary Chemistry |
The redox reactions catalyzed by oxidoreductases are vital in all parts of metabolism, but one particularly important area where these reactions occur is in the release of energy from nutrients. Here, reduced compounds such as glucose and fatty acids are oxidized, thereby releasing energy. This energy is transferred to NAD by reduction to NADH, as part of beta oxidation, glycolysis, and the citric acid cycle. In eukaryotes the electrons carried by the NADH that is produced in the cytoplasm are transferred into the mitochondrion (to reduce mitochondrial NAD) by mitochondrial shuttles, such as the malate-aspartate shuttle. The mitochondrial NADH is then oxidized in turn by the electron transport chain, which pumps protons across a membrane and generates ATP through oxidative phosphorylation. These shuttle systems also have the same transport function in chloroplasts.
Since both the oxidized and reduced forms of nicotinamide adenine dinucleotide are used in these linked sets of reactions, the cell maintains significant concentrations of both NAD and NADH, with the high NAD/NADH ratio allowing this coenzyme to act as both an oxidizing and a reducing agent. In contrast, the main function of NADPH is as a reducing agent in anabolism, with this coenzyme being involved in pathways such as fatty acid synthesis and photosynthesis. Since NADPH is needed to drive redox reactions as a strong reducing agent, the NADP/NADPH ratio is kept very low.
Although it is important in catabolism, NADH is also used in anabolic reactions, such as gluconeogenesis. This need for NADH in anabolism poses a problem for prokaryotes growing on nutrients that release only a small amount of energy. For example, nitrifying bacteria such as Nitrobacter oxidize nitrite to nitrate, which releases sufficient energy to pump protons and generate ATP, but not enough to produce NADH directly. As NADH is still needed for anabolic reactions, these bacteria use a nitrite oxidoreductase to produce enough proton-motive force to run part of the electron transport chain in reverse, generating NADH. | 0 | Theoretical and Fundamental Chemistry |
This theory is a little similar to the Lock and Key Theory, but at this time the active site is preprogrammed to bind perfectly to substrate in transition state rather than in ground state. The formation of transition state within the solution requires a large amount of energy to relocate solvent molecules and the reaction is slowed. So the active site can substitute solvent molecules and surround the substrates to minimize the counterproductive effect imposed by the solution. The presence of charged groups with the active site will attract substrates and ensure electrostatic complementarity. | 1 | Applied and Interdisciplinary Chemistry |
In the on-line process, the cleaning body moves through the tubes with the conveying medium and cleans them by means of its oversize compared to the tube diameter. In the range of diameters of up to 50 mm these cleaning bodies consist of sponge rubber, in larger diameters up to the size of oil pipelines it is a matter of scrapers or so-called pigs. Sponge rubber balls are applied mainly for cooling water, like sea, river, or cooling tower water. For the chemical or pharmaceutical industry, specially adapted cleaning bodies are imaginable but the conveying media flows are so weak that off-line processes are employed in most cases. Given the fact that the cleaning bodies are not allowed to remain in the conveying medium they have to be collected after passing through the tubes. In the case of sponge rubber balls this is done through special strainer sections; for scrapers or pigs an outward transfer station is provided. According to the Taprogge process, the sponge rubber balls are re-injected upstream of the system to be cleaned by a corresponding ball recirculating unit whereas the scraper or pig is mostly taken out by hand and re-injected into another collector. Sponge rubber balls therefore safeguard a continuous cleaning while the scraper or pig system is discontinuous. | 1 | Applied and Interdisciplinary Chemistry |
According to Ligand Field Theory, the ns orbital is involved in bonding to the ligands and forms a strongly bonding orbital which has predominantly ligand character and the correspondingly strong anti-bonding orbital which is unfilled and usually well above the lowest unoccupied molecular orbital (LUMO). Since the orbitals resulting from the ns orbital are either buried in bonding or elevated well above the valence, the ns orbitals are not relevant to describing the valence. Depending on the geometry of the final complex, either all three of the np orbitals or portions of them are involved in bonding, similar to the ns orbitals. The np orbitals if any that remain non-bonding still exceed the valence of the complex. That leaves the (n − 1)d orbitals to be involved in some portion of the bonding and in the process also describes the metal complexs valence electrons. The final description of the valence is highly dependent on the complexs geometry, in turn highly dependent on the d electron count and character of the associated ligands.
For example, in the MO diagram provided for the [Ti(HO)] the ns orbital – which is placed above (n − 1)d in the representation of atomic orbitals (AOs) – is used in a linear combination with the ligand orbitals, forming a very stable bonding orbital with significant ligand character as well as an unoccupied high energy antibonding orbital which is not shown. In this situation the complex geometry is octahedral, which means two of the d orbitals have the proper geometry to be involved in bonding. The other three d orbitals in the basic model do not have significant interactions with the ligands and remain as three degenerate non-bonding orbitals. The two orbitals that are involved in bonding form a linear combination with two ligand orbitals with the proper symmetry. This results in two filled bonding orbitals and two orbitals which are usually the lowest unoccupied molecular orbitals (LUMO) or the highest partially filled molecular orbitals – a variation on the highest occupied molecular orbitals (HOMO).
Crystal field theory is an alternative description of electronic configurations that is simplified relative to LFT. It rationalizes a number of phenomena, but does not describe bonding nor offer an explanation for why ns electrons are ionized before (n − 1)d electrons. | 0 | Theoretical and Fundamental Chemistry |
Proteorhodopsin belongs to a family of similar retinylidene proteins, most similar to its archaeal homologues halorhodopsin and bacteriorhodopsin. Sensory rhodopsin was discovered by Franz Christian Boll in 1876. Bacteriorhodopsin was discovered in 1971 and named in 1973 and is currently only known to exist in archaea, not bacteria. Halorhodopsin was first discovered and named in 1977.
Bacteriorhodopsin and Halorhodopsin both only exist in archaea whereas proteorhodopsin spans bacteria, archaea, and eukaryotes. Proteorhodopsin shares seven transmembrane α-helices retinal covalently linked by a Schiff base mechanism to a lysine residue in the seventh helix (helix G). Bacteriorhodopsin, like proteorhodopsin, is a light-driven proton pump. Sensory rhodopsin is a G-coupled protein involved in sight. | 0 | Theoretical and Fundamental Chemistry |
Avacopan was approved for medical use in the United States to treat anti-neutrophil cytoplasmic autoantibody-associated vasculitis in October 2021. | 1 | Applied and Interdisciplinary Chemistry |
* Reduced immunogenicity compared to attenuated vaccines
** Require adjuvants to improve immunogenicity
** Often require multiple doses ("booster" doses) to provide long-term immunity
* Can be difficult to isolate the specific antigen(s) which will invoke the necessary immune response
*It is not easy to supervise conjugation chemistry which leads to noncontinuous variation | 1 | Applied and Interdisciplinary Chemistry |
In Idrija, Slovenia, where the world’s second largest mercury (Hg) mine operated has a significant amount of Hg emissions into the atmosphere by a surface process of adsorption of Hg from and to soil particles surfaces, which results in a diffusion of Hg through the pores of soil. To calculate the emission flux for Hg, a Hg emission model was developed:
=E/(R*T )+n*ln[Hg]+m+0.003*R Equation 1</div>
in which the F is the flux of Hg emission, E is the activation energy, R is the gas constant, T is the soil temperature, n and m are constants, [Hg] is the Hg concentration, and 0.003* R accounts for the solar radiation since the solar radiation has the effect on the temperature, hence the solar radiation has the effect on the emission flux of Hg.
Once the Hg concentration data was gathered, a schematic model has been prepared for GIS input, which consisted of a digital elevation model (DEM), a satellite land use map, and EARS data. Using the inverse distance weighted (IDW) method from geostatistical tools in ArcGIS 9.3, a raster model of the Hg concentration has been produced for the Idrija area. | 1 | Applied and Interdisciplinary Chemistry |
The H NMR spectra were recorded at a resonance frequency of 400 MHz with a resolution of 0.0625 Hz or at 90 MHz with a resolution of 0.125 Hz. The spectral acquisition was carried out using a flip angle of 22.5 – 30.0 degrees and a pulse repetition time of 30 seconds. Samples were prepared by dissolution in deuterated chloroform (CDCl), deuterium oxide (DO), or deuterated dimethylsulfoxide (DMSO-d). Each spectrum is accompanied by a list of peaks with their respective intensities and chemical shifts reported in ppm and in Hz. Most spectra show the peak assignment. This collection contains ca 15,900 spectra and is being updated. | 0 | Theoretical and Fundamental Chemistry |
Buffer capacity is a quantitative measure of the resistance to change of pH of a solution containing a buffering agent with respect to a change of acid or alkali concentration. It can be defined as follows:
where is an infinitesimal amount of added base, or
where is an infinitesimal amount of added acid. pH is defined as −log[H], and d(pH) is an infinitesimal change in pH.
With either definition the buffer capacity for a weak acid HA with dissociation constant K can be expressed as
where [H] is the concentration of hydrogen ions, and is the total concentration of added acid. K is the equilibrium constant for self-ionization of water, equal to 1.0. Note that in solution H exists as the hydronium ion HO, and further aquation of the hydronium ion has negligible effect on the dissociation equilibrium, except at very high acid concentration.
This equation shows that there are three regions of raised buffer capacity (see figure 2).
* In the central region of the curve (coloured green on the plot), the second term is dominant, and Buffer capacity rises to a local maximum at pH = pK. The height of this peak depends on the value of pK. Buffer capacity is negligible when the concentration [HA] of buffering agent is very small and increases with increasing concentration of the buffering agent. Some authors show only this region in graphs of buffer capacity. Buffer capacity falls to 33% of the maximum value at pH = pK ± 1, to 10% at pH = pK ± 1.5 and to 1% at pH = pK ± 2. For this reason the most useful range is approximately pK ± 1. When choosing a buffer for use at a specific pH, it should have a pK value as close as possible to that pH.
* With strongly acidic solutions, pH less than about 2 (coloured red on the plot), the first term in the equation dominates, and buffer capacity rises exponentially with decreasing pH: This results from the fact that the second and third terms become negligible at very low pH. This term is independent of the presence or absence of a buffering agent.
* With strongly alkaline solutions, pH more than about 12 (coloured blue on the plot), the third term in the equation dominates, and buffer capacity rises exponentially with increasing pH: This results from the fact that the first and second terms become negligible at very high pH. This term is also independent of the presence or absence of a buffering agent. | 0 | Theoretical and Fundamental Chemistry |
Beweries, et al., developed a light-driven "closed cycle of water splitting using ansa-titanocene(III/IV) triflate complexes". | 0 | Theoretical and Fundamental Chemistry |
The SMD can be defined as the diameter of a drop having the same volume/surface area ratio as the entire spray.
SMD is especially important in calculations where the active surface area is important. Such areas include catalysis and applications in fuel combustion. | 1 | Applied and Interdisciplinary Chemistry |
Sulfur has four main oxidation states in nature, which are −2, +2, +4, and +6. The common sulfur species of each oxidation state are listed as follows:
S: HS; (CH)S; BaS
S: native, or elemental, sulfur
S: SCl
S: SO; sulfite ()
S: (HSO, CaSO); SF | 0 | Theoretical and Fundamental Chemistry |
Nod factors structurally are lipochitooligosaccharides (LCOs) that consist of an N-acetyl--glucosamine chain linked through β-1,4 linkage with a fatty acid of variable identity attached to a non reducing nitrogen in the backbone with various functional group substitutions at the terminal or non-terminal residues.
Nod factors are produced in complex mixtures differing in the following characteristics:
* Length of the chain can vary from three to six units of N-acetyl--glucosamine with the exception of M. loti which can produce Nod factors with two unit only.
* Presence or absence of strain-specific substitutions along the chain
* Identity of the fatty acid component
* Presence or absence of unsaturated fatty acids
Nod gene expression is induced by the presence of certain flavonoids in the soil, which are secreted by the plant and act as an attractant to bacteria and induce Nod factor production. Flavonoids activate NodD, a LysR family transcription factor, which binds to the nod box and initiates the transcription of the nod genes which encode the proteins necessary for the production of a wide range of LCOs. | 1 | Applied and Interdisciplinary Chemistry |
Hassan Naim is a Lebanese-Swiss biochemist. He currently holds the position of Director of the "Institut für Physiologische Chemie" (Institute for Physiological Chemistry/Biochemistry) at the University of Veterinary Medicine Hanover, while collaborating regularly with the University of Hannover. | 1 | Applied and Interdisciplinary Chemistry |
Among the thousands of species of plant pathogenic microorganisms, only a small minority have the capacity to infect a broad range of plant species. Most pathogens instead exhibit a high degree of host-specificity. Non-host plant species are often said to express non-host resistance. The term host resistance is used when a pathogen species can be pathogenic on the host species but certain strains of that plant species resist certain strains of the pathogen species. The causes of host resistance and non-host resistance can overlap. Pathogen host range is determined, among other things, by the presence of appropriate effectors that allow colonization of a particular host. Pathogen host range can change quite suddenly if, for example, the pathogen's capacity to synthesize a host-specific toxin or effector is gained by gene shuffling/mutation, or by horizontal gene transfer. | 1 | Applied and Interdisciplinary Chemistry |
Crosstalk can even be observed across membranes. Membrane interactions with the extracellular matrix (ECM) and with neighboring cells can trigger a variety of responses within the cell. However, the topography and mechanical properties of the ECM also come to play an important role in powerful, complex crosstalk with the cells growing on or inside the matrix. For example, integrin-mediated cytoskeleton assembly and even cell motility are affected by the physical state of the ECM. Binding of the α5β1 integrin to its ligand (fibronectin) activates the formation of fibrillar adhesions and actin filaments. Yet, if the ECM is immobilized, matrix reorganization of this kind and formation of fibrillar adhesions is inhibited. In turn, binding of the same integrin (α5β1) to an immobilized fibronectin ligand is seen to form highly phosphorylated focal contacts/focal adhesion (cells involved in matrix adhesion) within the membrane and reduces cell migration rates In another example of crosstalk, this change in the composition of focal contacts in the cytoskeleton can be inhibited by members of yet another pathway: inhibitors of myosin light-chain kinases or Rho kinases, H-7 or ML-7, which reduce cell contractility and consequently motility. (see figure 2). | 1 | Applied and Interdisciplinary Chemistry |
A common urban habitat, the lawn, consists of short grass and sometimes herbaceous plants. While modern artificial lawns have been connected to a negative environmental impact, lawns in the past have been more sustainable, and they promoted biodiversity and the growth of native plants. These historical lawns are impacting lawn design today to create more sustainable ‘alternative lawns’.
In Medieval Europe, lawns rich with flowers and herbaceous plants known as ‘flower meads’ are a good example of a more sustainable lawn. Since then, this idea has been used. In the Edwardian Era, lawns full of thyme, whose flowers attracted insects and pollinators, created biodiversity. A 20th century take on this lawn, the ‘enamelled mead’, has been used in England, and has the purpose of both aesthetics and for stormwater management.
During the height of the Renaissance, public areas became more common in new cities and infrastructure. These areas were carefully selected and would often be urban parks and gardens for the public to converse and relax at. Other than social uses, urban parks and gardens were used to improve the aesthetic of the urban environment they were present in. Urban spaces had environmental uses for the implementation of fresh air and reduced urban heating. | 1 | Applied and Interdisciplinary Chemistry |
KRP stands for kinesin related proteins. bimC is a subfamily of KRPs and its function is to separate the duplicated centrosomes during mitosis. | 1 | Applied and Interdisciplinary Chemistry |
Nucleotidomimetics do not generally qualify as foldamers. Most are designed to mimic single DNA bases, nucleosides, or nucleotides in order to nonspecifically target DNA. These have several different medicinal uses including anti-cancer, anti-viral, and anti-fungal applications. | 0 | Theoretical and Fundamental Chemistry |
A DID is an ion detector which uses a high-voltage electric discharge to produce ions. The detector uses an electrical discharge in helium to
generate high energy UV photons and metastable helium which ionizes all compounds except helium. The ions produce an electric current, which is the signal output of the detector. The greater the concentration of the component, the more ions are produced, and the greater the current. | 0 | Theoretical and Fundamental Chemistry |
Warm spraying is a novel modification of high velocity oxy-fuel spraying, in which the temperature of combustion gas is lowered by mixing nitrogen with the combustion gas, thus bringing the process closer to the cold spraying. The resulting gas contains much water vapor, unreacted hydrocarbons and oxygen, and thus is dirtier than the cold spraying. However, the coating efficiency is higher. On the other hand, lower temperatures of warm spraying reduce melting and chemical reactions of the feed powder, as compared to HVOF. These advantages are especially important for such coating materials as Ti, plastics, and metallic glasses, which rapidly oxidize or deteriorate at high temperatures. | 1 | Applied and Interdisciplinary Chemistry |
The solution of the equations is a flow velocity. It is a vector field—to every point in a fluid, at any moment in a time interval, it gives a vector whose direction and magnitude are those of the velocity of the fluid at that point in space and at that moment in time. It is usually studied in three spatial dimensions and one time dimension, although two (spatial) dimensional and steady-state cases are often used as models, and higher-dimensional analogues are studied in both pure and applied mathematics. Once the velocity field is calculated, other quantities of interest such as pressure or temperature may be found using dynamical equations and relations. This is different from what one normally sees in classical mechanics, where solutions are typically trajectories of position of a particle or deflection of a continuum. Studying velocity instead of position makes more sense for a fluid, although for visualization purposes one can compute various trajectories. In particular, the streamlines of a vector field, interpreted as flow velocity, are the paths along which a massless fluid particle would travel. These paths are the integral curves whose derivative at each point is equal to the vector field, and they can represent visually the behavior of the vector field at a point in time. | 1 | Applied and Interdisciplinary Chemistry |
Aerosol is defined as a suspension system of solid or liquid particles in a gas. An aerosol includes both the particles and the suspending gas, which is usually air. Meteorologists usually refer them as particle matter - PM2.5 or PM10, depending on their size. Frederick G. Donnan presumably first used the term aerosol during World War I to describe an aero-solution, clouds of microscopic particles in air. This term developed analogously to the term hydrosol, a colloid system with water as the dispersed medium. Primary aerosols contain particles introduced directly into the gas; secondary aerosols form through gas-to-particle conversion.
Key aerosol groups include sulfates, organic carbon, black carbon, nitrates, mineral dust, and sea salt, they usually clump together to form a complex mixture. Various types of aerosol, classified according to physical form and how they were generated, include dust, fume, mist, smoke and fog.
There are several measures of aerosol concentration. Environmental science and environmental health often use the mass concentration (M), defined as the mass of particulate matter per unit volume, in units such as μg/m. Also commonly used is the number concentration (N), the number of particles per unit volume, in units such as number per m or number per cm.
Particle size has a major influence on particle properties, and the aerosol particle radius or diameter (d) is a key property used to characterise aerosols.
Aerosols vary in their dispersity. A monodisperse aerosol, producible in the laboratory, contains particles of uniform size. Most aerosols, however, as polydisperse colloidal systems, exhibit a range of particle sizes. Liquid droplets are almost always nearly spherical, but scientists use an equivalent diameter to characterize the properties of various shapes of solid particles, some very irregular. The equivalent diameter is the diameter of a spherical particle with the same value of some physical property as the irregular particle. The equivalent volume diameter (d) is defined as the diameter of a sphere of the same volume as that of the irregular particle. Also commonly used is the aerodynamic diameter, d. | 0 | Theoretical and Fundamental Chemistry |
Chemical tube cleaning is understood to be the use of cleaning liquids or chemicals for removing layers and deposits. A typical example is the deliming of a coffee maker where scale is removed by means of acetic acid or citric acid. Depending on the field of application and tube material, special cleaning liquids may be used which also require a multi-stage treatment:
* chemical activation
* cleaning
* rinsing
This method of cleaning calls for a shutdown of the relevant system which causes undesired standstill periods. To safeguard a continuous production operation it may be necessary to install several systems. Another disadvantage: in the field of large-scale technology (reactor, heat exchanger, condenser, etc.), huge quantities of cleaning liquids would be required which would cause major disposal problems. A further problem occurs in the food industry through the possible toxicity of the cleaning liquid. Only the strict observance of rinsing instructions and an exact control of the admissible residue tolerances can remedy things here. This in turn requires expensive detection methods. Generally the process of chemical tube cleaning is applicable for any diameter, however practical limits of use ensue from the volume of a pipeline. | 1 | Applied and Interdisciplinary Chemistry |
As the equation originated with Henri, not with Michaelis and Menten, it is more accurate to call it the Henri–Michaelis–Menten equation, though it was Michaelis and Menten who realized that analysing reactions in terms of initial rates would be simpler, and as a result more productive, than analysing the time course of reaction, as Henri had attempted. Although Henri derived the equation he made no attempt to apply it. In addition, Michaelis and Menten understood the need for buffers to control the pH, but Henri did not. | 0 | Theoretical and Fundamental Chemistry |
Jeewanu is derived from Sanskrit jeewa, meaning "life", and anu, meaning the "smallest part of something", or the "indivisible". In contemporary Hindi, jeewanu also means unicellular organisms such as bacteria. Bahadur specifically used the term to represent the Indian philosophical tradition not only through the use of Sanskrit but also by inferring ideas on the origin of life from the Vedas. Bahadur, while employing the traditional Hindu philosophy, attempted to incorporate the advances in cell biology to the concept of abiogenesis. | 0 | Theoretical and Fundamental Chemistry |
Porphyrin ligands can be innocent (2-) or noninnocent (1-). In the enzymes chloroperoxidase and cytochrome P450, the porphyrin ligand sustains oxidation during the catalytic cycle, notably in the formation of Compound I. In other heme proteins, such as myoglobin, ligand-centered redox does not occur and the porphyrin is innocent. | 0 | Theoretical and Fundamental Chemistry |
The executive council of the Committee for Skeptical Inquiry (CSI) voted in April 2011 to include Walter McCrone in its "Pantheon of Skeptics". The Pantheon of Skeptics commemorates deceased distinguished fellows of CSI and their exceptional contributions to the cause of scientific skepticism. | 0 | Theoretical and Fundamental Chemistry |
Biochemists are scientists who are trained in biochemistry. They study chemical processes and chemical transformations in living organisms. Biochemists study DNA, proteins and cell parts. The word "biochemist" is a portmanteau of "biological chemist."
Biochemists also research how certain chemical reactions happen in cells and tissues and observe and record the effects of products in food additives and medicines.
Biochemist researchers focus on playing and constructing research experiments, mainly for developing new products, updating existing products and analyzing said products. It is also the responsibility of a biochemist to present their research findings and create grant proposals to obtain funds for future research.
Biochemists study aspects of the immune system, the expressions of genes, isolating, analyzing, and synthesizing different products, mutations that lead to cancers, and manage laboratory teams and monitor laboratory work. Biochemists also have to have the capabilities of designing and building laboratory equipment and devise new methods of producing correct results for products.
The most common industry role is the development of biochemical products and processes. Identifying substances' chemical and physical properties in biological systems is of great importance, and can be carried out by doing various types of analysis. Biochemists must also prepare technical reports after collecting, analyzing and summarizing the information and trends found.
In biochemistry, researchers often break down complicated biological systems into their component parts. They study the effects of foods, drugs, allergens and other substances on living tissues; they research molecular biology, the study of life at the molecular level and the study of genes and gene expression; and they study chemical reactions in metabolism, growth, reproduction, and heredity, and apply techniques drawn from biotechnology and genetic engineering to help them in their research. About 75% work in either basic or applied research; those in applied research take basic research and employ it for the benefit of medicine, agriculture, veterinary science, environmental science, and manufacturing. Each of these fields allows specialization; for example, clinical biochemists can work in hospital laboratories to understand and treat diseases, and industrial biochemists can be involved in analytical research work, such as checking the purity of food and beverages.
Biochemists in the field of agriculture research the interactions between herbicides with plants. They examine the relationships of compounds, determining their ability to inhibit growth, and evaluate the toxicological effects surrounding life.
Biochemists also prepare pharmaceutical compounds for commercial distribution.
Modern biochemistry is considered a sub-discipline of the biological sciences, due to its increased reliance on, and training, in accord with modern molecular biology. Historically, even before the term biochemist was formally recognized, initial studies were performed by those trained in basic chemistry, but also by those trained as physicians. | 1 | Applied and Interdisciplinary Chemistry |
The Weimberg pathway is an oxidative pathway where the D-xylose is oxidized to D-xylono-lactone by a D-xylose dehydrogenase followed by a lactonase to hydrolyze the lactone to D-xylonic acid. A xylonate dehydratase is splitting off a water molecule resulting in 2-keto 3-deoxy-xylonate. 2-keto-3-deox-D-xylonate dehydratase forms the α-ketoglutarate semialdehyde. This is subsequently oxidised via α-ketoglutarate semialdehyde dehydrogenase to yield 2-ketoglutarate which serves as a key intermediate in the citric acid cycle. | 1 | Applied and Interdisciplinary Chemistry |
A Lorentz force velocimetry system is called Lorentz force flowmeter (LFF). An LFF measures the integrated or bulk Lorentz force resulting from the interaction between a liquid metal in motion and an applied magnetic field. In this case, the characteristic length of the magnetic field is of the same order of magnitude as the dimensions of the channel. It must be addressed that in the case where localized magnetic fields are used, it is possible to perform local velocity measurements and thus the term Lorentz force velocimeter is used. | 1 | Applied and Interdisciplinary Chemistry |
Xylene is flammable but of modest acute toxicity, with ranges from 200 to 5000 mg/kg for animals. Oral for rats is 4300 mg/kg. The principal mechanism of detoxification is oxidation to methylbenzoic acid and hydroxylation to hydroxylene.
The main effect of inhaling xylene vapor is depression of the central nervous system (CNS), with symptoms such as headache, dizziness, nausea and vomiting. At an exposure of 100 ppm, one may experience nausea or a headache. At an exposure between 200 and 500 ppm, symptoms can include feeling "high", dizziness, weakness, irritability, vomiting, and slowed reaction time.
The side effects of exposure to low concentrations of xylene () are reversible and do not cause permanent damage. Long-term exposure may lead to headaches, irritability, depression, insomnia, agitation, extreme tiredness, tremors, hearing loss, impaired concentration and short-term memory loss. A condition called chronic solvent-induced encephalopathy, commonly known as "organic-solvent syndrome" has been associated with xylene exposure. There is very little information available that isolates xylene from other solvent exposures in the examination of these effects.
Hearing disorders have been also linked to xylene exposure, both from studies with experimental animals, as well as clinical studies.
Xylene is also a skin irritant and strips the skin of its oils, making it more permeable to other chemicals. The use of impervious gloves and masks, along with respirators where appropriate, is recommended to avoid occupational health issues from xylene exposure.
Xylenes are metabolized to methylhippuric acids. The presence of methylhippuric acid can be used as a biomarker to determine exposure to xylene. | 1 | Applied and Interdisciplinary Chemistry |
There are a few old studies indicating efficacy of lithium for acute depression with lithium having the same efficacy as tricyclic antidepressants. A recent study concluded that lithium works best on chronic and recurrent depression when compared to modern antidepressant (i.e. citalopram) but not for patients with no history of depression. | 1 | Applied and Interdisciplinary Chemistry |
In fluid descriptions of plasmas (see plasma modeling and magnetohydrodynamics (MHD)) one does not consider the velocity distribution. This is achieved by replacing with plasma moments such as number density , flow velocity and pressure . They are named plasma moments because the -th moment of can be found by integrating over velocity. These variables are only functions of position and time, which means that some information is lost. In multifluid theory, the different particle species are treated as different fluids with different pressures, densities and flow velocities. The equations governing the plasma moments are called the moment or fluid equations.
Below the two most used moment equations are presented (in SI units). Deriving the moment equations from the Vlasov equation requires no assumptions about the distribution function. | 1 | Applied and Interdisciplinary Chemistry |
To have an A- and B-term in the MCD spectrum, a molecule must contain degenerate excited states (A-term) and excited states close enough in energy to allow mixing (B-term). One case exemplifying these conditions is a square planar, d complex such as [(n-CH)N]Pt(CN). In addition to containing A- and B-terms, this example demonstrates the effects of spin-orbit coupling in metal to ligand charge transfer (MLCT) transitions. As shown in figure 1, the molecular orbital diagram of [(n-CH)N]Pt(CN) reveals MLCT into the antibonding π* orbitals of cyanide. The ground state is diamagnetic (thereby eliminating any C-terms) and the LUMO is the a. The dipole-allowed MLCT transitions are a-a and e-a. Another transition, b-a, is a weak (orbitally forbidden singlet) but can still be observed in MCD.
Because A- and B-terms arise from the properties of states, all singlet and triplet excited states are given in figure 2.
Mixing of all these singlet and triplet states will occur and is attributed to the spin orbit coupling of platinum 5d orbitals (ζ ~ 3500 cm), as shown in figure 3. The black lines on the figure indicate the mixing of A with E to give two A states. The red lines show the E, E, A, and B states mixing to give four E states. The blue lines indicate remnant orbitals after spin-orbit coupling that are not a result of mixing. | 0 | Theoretical and Fundamental Chemistry |
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