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Leigh and co-workers recently began to explore a strategy in which template ions could also play an active role in promoting the crucial final covalent bond forming reaction that captures the interlocked structure (i.e., the metal has a dual function, acting as a template for entwining the precursors and catalyzing covalent bond formation between the reactants). | 0 | Theoretical and Fundamental Chemistry |
Total petroleum hydrocarbons (TPH) is a term used for any mixture of hydrocarbons that are found in crude oil. There are several hundred of these compounds, but not all occur in any one sample. Crude oil is used to make petroleum products, which can contaminate the environment. Because there are so many different chemicals in crude oil and in other petroleum products, it is not practical to measure each one separately. However, it is useful to measure the total amount of TPH at a site. Chemicals that occur in TPH include hexane, benzene, toluene, xylenes, naphthalene, and fluorene, other constituents of gasoline, jet fuels, mineral oils, and of other petroleum products. Petroleum hydrocarbon ranges are monitored at various levels depending on the state and testing site.
TPH is the sum of volatile petroleum hydrocarbons (VPH) and extractable petroleum hydrocarbons (EPH). VPH is also known as petrol (or gasoline) range organics (PRO or GRO) and includes hydrocarbons from C6-C10. Diesel range organics (DRO) includes hydrocarbons from C10-C28.
Various methods to analyze the components of TPH are introduced in a Nordic report. The report evaluates critically various new methods replacing the old ones using banned ozone depleting substances. | 0 | Theoretical and Fundamental Chemistry |
* Gold. 1990. Organic Compounds in Biological Systems, 2nd ed. John Wiley & Sons, Inc.
* [https://web.archive.org/web/20100213004815/http://faculty.mansfield.edu/bganong/biochemistry/reagents.htm Chemical Reagents] | 0 | Theoretical and Fundamental Chemistry |
Source:
* 1991 Chris H. Greene: "For his many contributions to atomic and molecular theory including studies of resonance vibronic processes, multiple electron excitations, photo-absorption in external fields, and threshold effects of long range forces."
* 1993 Timothy E. Chupp: "For his contributions to the development of high density polarized noble gases by spin exchange with optically pumped alkali atoms and in particular for his leadership and use of polarized 3He as a target for fundamental experiments in nuclear physics."
* 1995 Randall G. Hulet: "For his contributions to a broad range of important problems in atomic and optical physics including cavity quantum electrodynamics, quantum jumps, ion storage, and laser cooling of atoms. In the latter field, in particular for his demonstration of multiphoton cooling involving Doppleron resonances in neutral Lithium and his collision experiments with cooled Lithium vapor."
* 1997 Eric Allin Cornell and Wolfgang Ketterle: "For achieving Bose-Einstein condensation of an atomic gas, for creating techniques for studying the Bose condensate, and for measuring the physical properties of the weakly interacting atomic Bose gas."
* 1999 Mark G. Raizen: "For his pioneering advances in the experimental study of atom optics, and especially for the insightful connections he has developed between this discipline and studies of chaotic dynamics, condensed matter physics, and dissipative quantum systems."
* 2001 Christopher Monroe: "For his pivotal experiments that implemented quantum logic using trapped atomic ions, and for his fundamental studies of coherence and decoherence in entangled quantum systems."
* 2003 Mark A. Kasevich: "For developing atom interferometer inertial sensors with unprecedented precision, and for pioneering studies of Bose-Einstein condensates, especially the achievement of non-classical spin states and the demonstration of a mode-locked atom laser."
* 2005 Deborah Jin:
* 2007 Jun Ye: "For advances in precision measurement, including techniques for stabilizing and measuring optical frequencies, controlling the phase of femtosecond laser pulses, and measuring molecular transitions."
* 2009 Mikhail Lukin: "For pioneering theoretical and experimental work at the interface between quantum optics, quantum information processing, and the quantum many body problem."
* 2011 Cheng Chin: "For pioneering work in strongly interacting Fermi gas and few body physics including the discovery of the Effimov effect."
* 2013 Markus Greiner: "For seminal contributions to the field of ultracold atoms, including the observation of the superfluid-to-Mott-insulator transition, the study of the BEC-BCS cross over for fermions, and the development of imaging techniques for atoms in optical lattices with single-atom resolution"
* 2015 Ian Spielman: "For the development of quantum simulations using ultra-cold atoms, creation of synthetic electromagnetic fields, demonstration of synthetic spinorbit coupling, and applications to studying new physical systems."
* 2017 Martin Zwierlein: "For seminal studies of ultracold Fermi gases, including precision measurements of the equation of state, the observation of superfluidity, solitons, vortices, and polarons, the realization of a microscope for fermions in a lattice; and the production of chemically stable polar molecules."
* 2019 Kang-Kuen Ni: "For seminal work on ultracold molecules, including original contributions to the understanding of chemical reactions in the quantum regime, deterministic creation of individual molecules with optical tweezers, and development of novel, high-precision techniques to interrogate and control the complete set of internal molecular resources."
* 2021 Monika Schleier-Smith: "For seminal work in quantum optics and for discoveries at the intersection of AMO, condensed matter, and quantum information, including original contributions to spin squeezing in optical cavities, engineering long-range interactions for quantum simulations, and metrology, and for theoretical development of a measurement protocol related to the scrambling of quantum information."
* 2023 Adam M. Kaufman: "For seminal developments in optical tweezer arrays and clocks based on alkaline earth atoms, with applications to metrology and quantum information processing." | 0 | Theoretical and Fundamental Chemistry |
Single nucleotide polymorphism (SNP) in langerin gene may affect the stability as well as the affinity of the protein for some carbohydrates. The most common polymorphism is a replacement of alanine for valine in the 278. position (rs741326). Allelic frequency of this polymorphism is up to 48 %, but it probably does not have any influence on stability and affinity of langerin. Substitution of asparagine for aspartic acid in the 288. position leads to 10-fold reduction in the ability to recognize mannose-BSA. A substitution of tryptophane for arginine in the 264. position leads to a loss of Birbeck granules. | 1 | Applied and Interdisciplinary Chemistry |
The term "triangle of death" was first used with regard to the region in a September 2004 scientific publication in the Lancet Oncology. | 1 | Applied and Interdisciplinary Chemistry |
Isotope analysis has been particularly useful in archaeology as a means of characterization. Characterization of artifacts involves determining the isotopic composition of possible source materials such as metal ore bodies and comparing these data to the isotopic composition of analyzed artifacts. A wide range of archaeological materials such as metals, glass and lead-based pigments have been sourced using isotopic characterization. Particularly in the Bronze Age Mediterranean, lead isotope analysis has been a useful tool for determining the sources of metals and an important indicator of trade patterns. Interpretation of lead isotope data is, however, often contentious and faces numerous instrumental and methodological challenges. Problems such as the mixing and re-using of metals from different sources, limited reliable data and contamination of samples can be difficult problems in interpretation. | 0 | Theoretical and Fundamental Chemistry |
Plant virus transmission from generation to generation occurs in about 20% of plant viruses. When viruses are transmitted by seeds, the seed is infected in the generative cells and the virus is maintained in the germ cells and sometimes, but less often, in the seed coat. When the growth and development of plants is delayed because of situations like unfavorable weather, there is an increase in the amount of virus infections in seeds. There does not seem to be a correlation between the location of the seed on the plant and its chances of being infected. Little is known about the mechanisms involved in the transmission of plant viruses via seeds, although it is known that it is environmentally influenced and that seed transmission occurs because of a direct invasion of the embryo via the ovule or by an indirect route with an attack on the embryo mediated by infected gametes. These processes can occur concurrently or separately depending on the host plant. It is unknown how the virus is able to directly invade and cross the embryo and boundary between the parental and progeny generations in the ovule.
Many plants species can be infected through seeds including but not limited to the families Leguminosae, Solanaceae, Compositae, Rosaceae, Cucurbitaceae, Gramineae. Bean common mosaic virus is transmitted through seeds. | 1 | Applied and Interdisciplinary Chemistry |
In many applications of diffusiophoresis, the motion is driven by gradients in the concentration of a salt (electrolyte) concentration, such as sodium chloride in water. Colloidal particles in water are typically charged, and there is an electrostatic potential, called a zeta potential at their surface. This charged surface of the colloidal particle interacts with a gradient in salt concentration, and this gives rise to diffusiophoretic velocity given by
where is the permittivity of water, is the viscosity of water, is the zeta potential of the colloidal particle in the salt solution, is the reduced difference between the diffusion constant of the positively charged ion, , and the diffusion constant of the negatively charged ion, , and is the salt concentration. is the gradient, i.e., rate of change with position, of the logarithm of the salt concentration, which is equivalent to the rate of change of the salt concentration, divided by the salt concentration – it is effectively one over the distance over which the concentration decreases by a factor of e. The above equation is approximate, and only valid for 1:1 electrolytes such as sodium chloride.
Note that there are two contributions to diffusiophoresis of a charged particle in a salt gradient, which give rise to the two terms in the above equation for . The first is due to the fact that whenever there is a salt concentration gradient, then unless the diffusion constants of the positive and negative ions are exactly equal to each other, there is an electric field, i.e., the gradient acts a little like a capacitor. This electric filed generated by the salt gradient drives electrophoresis of the charged particle, just as an externally applied electric field does. This gives rise to the first term in the equation above, i.e., diffusiophoresis at a velocity .
The second part is due to the surface free energy of the surface of a charged particle, decreasing with increasing salt concentration, this is a similar mechanism to that found in diffusiophoresis in gradients of neutrial substances. This gives rise to the second part of the diffusiophoretic velocity . Note that this simple theory predicts that this contribution to the diffusiophoretic motion is always up a salt concentration gradient, it always moves particles towards higher salt concentration. By contrast, the sign of the electric-field contribution to diffusiophoresis depends on the sign of . So for example, for a negatively charged particle, , and if the positively charged ions diffuse faster than the negatively charged ones, then this term will push particles down a salt gradient, but if it is the negatively charged ions that diffuse faster, then this term pushes the particles up the salt gradient. | 0 | Theoretical and Fundamental Chemistry |
X-ray spectroelectrochemistry is a technique that studies the interaction of high-energy radiation with matter during an electrode process. X-rays can originate absorption, emission or scattering phenomena, allowing to perform both quantitative and qualitative analysis depending on the phenomenon taking place. All these processes involve electronic transitions in the inner layers of the atoms involved. Particularly, it is interesting to study the processes of radiation, absorption and emission that take place during an electron transfer reaction. In these processes, the promotion or relaxation of an electron can occur between an outer shell and an inner shell of the atom. | 0 | Theoretical and Fundamental Chemistry |
In hydrodynamics, a plume or a column is a vertical body of one fluid moving through another. Several effects control the motion of the fluid, including momentum (inertia), diffusion and buoyancy (density differences). Pure jets and pure plumes define flows that are driven entirely by momentum and buoyancy effects, respectively. Flows between these two limits are usually described as forced plumes or buoyant jets. "Buoyancy is defined as being positive" when, in the absence of other forces or initial motion, the entering fluid would tend to rise. Situations where the density of the plume fluid is greater than its surroundings (i.e. in still conditions, its natural tendency would be to sink), but the flow has sufficient initial momentum to carry it some distance vertically, are described as being negatively buoyant. | 1 | Applied and Interdisciplinary Chemistry |
The equilibrium constant of a chemical reaction is the value of its reaction quotient at chemical equilibrium, a state approached by a dynamic chemical system after sufficient time has elapsed at which its composition has no measurable tendency towards further change. For a given set of reaction conditions, the equilibrium constant is independent of the initial analytical concentrations of the reactant and product species in the mixture. Thus, given the initial composition of a system, known equilibrium constant values can be used to determine the composition of the system at equilibrium. However, reaction parameters like temperature, solvent, and ionic strength may all influence the value of the equilibrium constant.
A knowledge of equilibrium constants is essential for the understanding of many chemical systems, as well as biochemical processes such as oxygen transport by hemoglobin in blood and acid–base homeostasis in the human body.
Stability constants, formation constants, binding constants, association constants and dissociation constants are all types of equilibrium constants. | 0 | Theoretical and Fundamental Chemistry |
Aquo complexes of lanthanide(III) ions are eight- and nine-coordinate, reflecting the large size of the metal centres. | 0 | Theoretical and Fundamental Chemistry |
To fully gauge the viability of calcium looping as a capture process, it is necessary to consider the political, environmental, and health effects of the process as well. | 1 | Applied and Interdisciplinary Chemistry |
A rotameter consists of a tapered tube, typically made of glass with a float (a shaped weight, made either of anodized aluminum or a ceramic), inside that is pushed up by the drag force of the flow and pulled down by gravity. The drag force for a given fluid and float cross section is a function of flow speed squared only, see drag equation.
A higher volumetric flow rate through a given area increases flow speed and drag force, so the float will be pushed upwards. However, as the inside of the rotameter is cone shaped (widens), the area around the float through which the medium flows increases, the flow speed and drag force decrease until there is mechanical equilibrium with the float's weight.
Floats are made in many different shapes, with spheres and ellipsoids being the most common. The float may be diagonally grooved and partially colored so that it rotates axially as the fluid passes. This shows if the float is stuck since it will only rotate if it is free. Readings are usually taken at the top of the widest part of the float; the center for an ellipsoid, or the top for a cylinder. Some manufacturers use a different standard.
The "float" must not float in the fluid: it has to have a higher density than the fluid, otherwise it will float to the top even if there is no flow.
The mechanical nature of the measuring principle provides a flow measurement device that does not require any electrical power. If the tube is made of metal, the float position is transferred to an external indicator via a magnetic coupling. This capability has considerably expanded the range of applications for the variable area flowmeter, since the measurement can observed remotely from the process or used for automatic control. | 1 | Applied and Interdisciplinary Chemistry |
Pheromones of certain pest insect species, such as the Japanese beetle, acrobat ant, and the spongy moth, can be used to trap the respective insect for monitoring purposes, to control the population by creating confusion, to disrupt mating, and to prevent further egg laying. | 1 | Applied and Interdisciplinary Chemistry |
Sonication can be used for the production of nanoparticles, such as nanoemulsions, nanocrystals, liposomes and wax emulsions, as well as for wastewater purification, degassing, extraction of seaweed polysaccharides and plant oil, extraction of anthocyanins and antioxidants, production of biofuels, crude oil desulphurization, cell disruption, polymer and epoxy processing, adhesive thinning, and many other processes. It is applied in pharmaceutical, cosmetic, water, food, ink, paint, coating, wood treatment, metalworking, nanocomposite, pesticide, fuel, wood product and many other industries.
Sonication can be used to speed dissolution, by breaking intermolecular interactions. It is especially useful when it is not possible to stir the sample, as with NMR tubes. It may also be used to provide the energy for certain chemical reactions to proceed. Sonication can be used to remove dissolved gases from liquids (degassing) by sonicating the liquid while it is under a vacuum. This is an alternative to the freeze-pump-thaw and sparging methods.
In biological applications, sonication may be sufficient to disrupt or deactivate a biological material. For example, sonication is often used to disrupt cell membranes and release cellular contents. This process is called sonoporation. Small unilamellar vesicles (SUVs) can be made by sonication of a dispersion of large multilamellar vesicles (LMVs). Sonication is also used to fragment molecules of DNA, in which the DNA subjected to brief periods of sonication is sheared into smaller fragments.
Sonication is commonly used in nanotechnology for evenly dispersing nanoparticles in liquids. Additionally, it is used to break up aggregates of micron-sized colloidal particles.
Sonication can also be used to initiate crystallisation processes and even control polymorphic crystallisations. It is used to intervene in anti-solvent precipitations (crystallisation) to aid mixing and isolate small crystals.
Sonication is the mechanism used in ultrasonic cleaning—loosening particles adhering to surfaces. In addition to laboratory science applications, sonicating baths have applications including cleaning objects such as spectacles and jewelry.
Sonication is used in food industry as well. Main applications are for dispersion to save expensive emulgators (mayonnaise) or to speed up filtration processes (vegetable oil etc.). Experiments with sonication for artificial ageing of liquors and other alcoholic beverages were conducted.
Soil samples are often subjected to ultrasound in order to break up soil aggregates; this allows the study of the different constituents of soil aggregates (especially soil organic matter) without subjecting them to harsh chemical treatment.
Sonication is also used to extract microfossils from rock.
An ultrasonic bath or an ultrasonic probe system is used for extraction. For instance, this technique was suggested to remove isoflavones from soybeans and phenolic compounds from wheat bran and coconut shell powder. The outcomes differ for every raw material and solvent utilized and the other extraction techniques. Acoustic or ultrasonic cavitation is the basis for the operation of ultrasound-assisted extraction. | 1 | Applied and Interdisciplinary Chemistry |
Self-cleaning screen media was initially engineered to resolve screen cloth blinding, clogging and pegging problems. The idea was to place crimped wires side by side on a flat surface, creating openings and then, in some way, holding them together over the support bars (crown bars or bucker bars). This would allow the wires to be free to vibrate between the support bars, preventing blinding, clogging and pegging of the cloth. Initially, crimped longitudinal wires on self-cleaning cloth were held together over support bars with woven wire. In the 50s, some manufacturers started to cover the woven cross wires with caulking or rubber to prevent premature wear of the crimps (knuckles on woven wires). One of the pioneer products in this category was ONDAP GOMME made by the French manufacturer Giron. During the mid 90s, Major Wire Industries Ltd., a Quebec manufacturer, developed a “hybrid” self-cleaning screen cloth called Flex-Mat, without woven cross wires. In this product, the crimped longitudinal wires are held in place by polyurethane strips. Rather than locking (impeding) vibration over the support bars due to woven cross wires, polyurethane strips reduce vibration of longitudinal wires over the support bars, thus allowing vibration from hook to hook. Major Wire quickly started to promote this product as a high-performance screen that helped producers screen more in-specification material for less cost and not simply a problem solver. They claimed that the independent vibrating wires helped produce more product compared to a woven wire cloth with the same opening (aperture) and wire diameter. This higher throughput would be a direct result of the higher vibration frequency of each independent wire of the screen cloth (calculated in hertz) compared to the shaker vibration (calculated in RPM), accelerating the stratification of the material bed. Another benefit that helped the throughput increase is that hybrid self-cleaning screen media offered a better open area percentage than woven wire screen media. Due to its flat surface (no knuckles), hybrid self-cleaning screen media can use a smaller wire diameter for the same aperture than woven wire and still lasts as long, resulting in a greater opening percentage. | 1 | Applied and Interdisciplinary Chemistry |
A caplet is a smooth, coated, oval-shaped medicinal tablet in the general shape of a capsule. Many caplets have an indentation running down the middle, so they may be split in half more easily. Consumers have viewed capsules as the most effective way to take medication ever since they first appeared. For this reason, producers of drugs such as OTC analgesics wanting to emphasize the strength of their product developed the "caplet", a portmanteau of capsule-shaped tablet, in order to tie this positive association to more efficiently produced tablet pills as well as being an easier-to-swallow shape than the usual disk-shaped tablet. | 1 | Applied and Interdisciplinary Chemistry |
Polytypes are a special case of polymorphs, where multiple close-packed crystal structures differ in one dimension only. Polytypes have identical close-packed planes, but differ in the stacking sequence in the third dimension perpendicular to these planes. Silicon carbide (SiC) has more than 170 known polytypes, although most are rare. All the polytypes of SiC have virtually the same density and Gibbs free energy. The most common SiC polytypes are shown in Table 1.
Table 1: Some polytypes of SiC.
A second group of materials with different polytypes are the transition metal dichalcogenides, layered materials such as molybdenum disulfide (MoS). For these materials the polytypes have more distinct effects on material properties, e.g. for MoS, the 1T polytype is metallic in character, while the 2H form is more semiconducting.
Another example is tantalum disulfide, where the common 1T as well as 2H polytypes occur, but also more complex mixed coordination types such as 4Hb and 6R, where the trigonal prismatic and the octahedral geometry layers are mixed. Here, the 1T polytype exhibits a charge density wave, with distinct influence on the conductivity as a function of temperature, while the 2H polytype exhibits superconductivity.
ZnS and CdI are also polytypical. It has been suggested that this type of polymorphism is due to kinetics where screw dislocations rapidly reproduce partly disordered sequences in a periodic fashion. | 0 | Theoretical and Fundamental Chemistry |
Axiomatic thermodynamics is a mathematical discipline that aims to describe thermodynamics in terms of rigorous axioms, for example by finding a mathematically rigorous way to express the familiar laws of thermodynamics.
The first attempt at an axiomatic theory of thermodynamics was Constantin Carathéodorys 1909 work Investigations on the Foundations of Thermodynamics', which made use of Pfaffian systems and the concept of adiabatic accessibility, a notion that was introduced by Carathéodory himself. In this formulation, thermodynamic concepts such as heat, entropy, and temperature are derived from quantities that are more directly measurable. Theories that came after, differed in the sense that they made assumptions regarding thermodynamic processes with arbitrary initial and final states, as opposed to considering only neighboring states. | 0 | Theoretical and Fundamental Chemistry |
TaqMan probes consist of a fluorophore covalently attached to the 5’-end of the oligonucleotide probe and a quencher at the 3’-end. Several different fluorophores (e.g. 6-carboxyfluorescein, acronym: FAM, or tetrachlorofluorescein, acronym: TET) and quenchers (e.g. tetramethylrhodamine, acronym: TAMRA) are available. The quencher molecule quenches the fluorescence emitted by the fluorophore when excited by the cycler’s light source via Förster resonance energy transfer (FRET). As long as the fluorophore and the quencher are in proximity, quenching inhibits any fluorescence signals.
TaqMan probes are designed such that they anneal within a DNA region amplified by a specific set of primers. (Unlike the diagram, the probe binds to single stranded DNA.) TaqMan probes can be conjugated to a minor groove binder (MGB) moiety, dihydrocyclopyrroloindole tripeptide (DPI), in order to increase its binding affinity to the target sequence; MGB-conjugated probes have a higher melting temperature (T) due to increased stabilization of van der Waals forces. As the Taq polymerase extends the primer and synthesizes the nascent strand (from the single-stranded template), the 5 to 3 exonuclease activity of the Taq polymerase degrades the probe that has annealed to the template. Degradation of the probe releases the fluorophore from it and breaks the proximity to the quencher, thus relieving the quenching effect and allowing fluorescence of the fluorophore. Hence, fluorescence detected in the quantitative PCR thermal cycler is directly proportional to the fluorophore released and the amount of DNA template present in the PCR. | 1 | Applied and Interdisciplinary Chemistry |
In the case of low material loss, the Nicolson–Ross–Weir method is known to be unstable for sample thicknesses at integer multiples of one half wavelength due to resonance phenomenon. Improvements over the standard algorithm have been presented in engineering literature to alleviate this effect. Furthermore, complete filling of a waveguide with sample material may pose a particular challenge: presence of gaps during the filling of the waveguide section would excite higher-order modes, which may yield errors in scattering parameter results. In such cases, more advanced methods based on the rigorous modal analysis of partially-filled waveguides or optimization methods can be used. A modification of the method for single-port measurements was also reported.
In addition to homogenous materials, the extension of the method was developed to obtain constitutive parameters of isotropic and bianisotropic metamaterials. | 0 | Theoretical and Fundamental Chemistry |
In the study of partial differential equations, particularly in fluid dynamics, a self-similar solution is a form of solution which is similar to itself if the independent and dependent variables are appropriately scaled. Self-similar solutions appear whenever the problem lacks a characteristic length or time scale (for example, the Blasius boundary layer of an infinite plate, but not of a finite-length plate). These include, for example, the Blasius boundary layer or the Sedov–Taylor shell. | 1 | Applied and Interdisciplinary Chemistry |
Uranus has an active methane cycle. Methane is converted to hydrocarbons through photolysis which condenses and as they are heated, release methane which rises to the upper atmosphere.
Studies by Grundy et al. (2006) indicate active carbon cycles operates on Titania, Umbriel and Ariel and Oberon through the ongoing sublimation and deposition of carbon dioxide, though some is lost to space over long periods of time. | 0 | Theoretical and Fundamental Chemistry |
In Norway as of July 2010, all new housing of more than two storeys, all new hotels, care homes, and hospitals must be sprinklered. Other Nordic countries require or soon will require sprinklers in new care homes, and in Finland a third of care homes were retrofitted with sprinklers. A fire in an illegal immigrant detention center at Schiphol Airport in the Netherlands on 27 October 2005 killed 11 detainees, and led to the retrofitting of sprinklers in all similarly-designed prisons in the Netherlands. A fire at Düsseldorf Airport on 11 April 1996 which killed 17 people led to sprinklers being retrofitted in all major German airports. Most European countries also require sprinklers in shopping centers, in large warehouses, and in high-rise buildings.
Renewed interest in and support for sprinkler systems in the UK has resulted in sprinkler systems being more widely installed. In schools, for example, the government has issued recommendations through Building Bulletin 100, a design guide for fire safety in schools, that most new schools, except for a few low risk schools, should be constructed with sprinkler protection. In 2011, Wales became the first country in the world where sprinklers are compulsory in all new homes. The law applies to newly built houses and blocks of flats, as well as care homes and university halls of residence. In Scotland, all new schools are sprinklered, as are new care homes, sheltered housing and high rise flats.
In the UK, since the 1990s sprinklers have gained recognition within the Building Regulations (England and Wales) and Scottish Building Standards and under certain circumstances, the presence of sprinkler systems is deemed to provide a form of alternative compliance to some parts of the codes. For example, the presence of a sprinkler system will usually permit doubling of compartment sizes and increases in travel distances (to fire exits) as well as allowing a reduction in the fire rating of internal compartment walls. | 1 | Applied and Interdisciplinary Chemistry |
Migratory aptitude is the relative ability of a migrating group to migrate in a rearrangement reaction. Migratory aptitudes vary in different reactions, depending on multiple factors.
In the Baeyer-Villiger reaction, the more substituted group, in general, migrates. In the pinacol rearrangement, the order of migratory aptitude has not been determined unambiguously, but some trends have been determined. For example, relative migratory aptitudes for alkyl substituents is Hydride >Phenide>C(CH)> CH > CH.
More bulky groups have more tendency to migrate. | 0 | Theoretical and Fundamental Chemistry |
Milk lipids are secreted in a unique manner by lactocytes, which are specialized epithelial cells within the alveoli of the lactating mammary gland.
The process takes place in multiple stages. First, fat synthesized within the endoplasmic reticulum accumulates in droplets between the inner and outer phospholipid monolayers of the endoplasmic reticulum membrane. As these droplets increase in size, the two monolayers separate further and eventually pinch off. This leads to the surrounding of the droplet in a phospholipid monolayer that allows it to disperse within the aqueous cytoplasm. In the next stage, lipid droplets then migrate to the apical surface of the cell, where plasma membrane subsequently envelops the droplet and extrudes together with it. It fully encases the fat droplet in an additional bilayer of phospholipids. The milk fat globule thus released into the glandular lumen, measuring 3-6 μm in average diameter, is surrounded by a phospholipid trilayer containing associated proteins, carbohydrates, and lipids derived primarily from the membrane of the secreting lactocyte. This trilayer is collectively known as MFGM.
This secretion process occurs in all types of mammalian milk, including human and bovine. However, it is distinct from the lipid secretion mechanism used by all other non-mammary cells. That makes MFGM unique to milk and it is not present in non-dairy food products. | 1 | Applied and Interdisciplinary Chemistry |
The first study which detected and quantified submarine groundwater discharge on a regional basis was done by Moore (1996) in the South Atlantic Bight off South Carolina. He measured enhanced radium-226 concentrations within the water column near shore and up to about from the shoreline. Radium-226 is a decay product of thorium-230, which is produced within sediments and supplied by rivers. However, these sources could not explain the high concentrations present in the study area. Moore (1996) hypothesized that submarine groundwater, enriched in radium-226, was responsible for the high concentrations. This hypothesis has been tested numerous times at sites around the world and confirmed at each site. | 0 | Theoretical and Fundamental Chemistry |
Esketamine is eliminated from the human body more quickly than arketamine (R(–)-ketamine) or racemic ketamine, although arketamine slows the elimination of esketamine. | 0 | Theoretical and Fundamental Chemistry |
Silicon can form sigma bonds to other silicon atoms (and disilane is the parent of this class of compounds). However, it is difficult to prepare and isolate SiH (analogous to the saturated alkane hydrocarbons) with n greater than about 8, as their thermal stability decreases with increases in the number of silicon atoms. Silanes higher in molecular weight than disilane decompose to polymeric polysilicon hydride and hydrogen. But with a suitable pair of organic substituents in place of hydrogen on each silicon it is possible to prepare polysilanes (sometimes, erroneously called polysilenes) that are analogues of alkanes. These long chain compounds have surprising electronic properties - high electrical conductivity, for example - arising from sigma delocalization of the electrons in the chain.
Even silicon–silicon pi bonds are possible. However, these bonds are less stable than the carbon analogues. Disilane and longer silanes are quite reactive compared to alkanes. Disilene and disilynes are quite rare, unlike alkenes and alkynes. Examples of disilynes, long thought to be too unstable to be isolated were reported in 2004. | 0 | Theoretical and Fundamental Chemistry |
Environmental radioactivity is not limited to actinides; non-actinides such as radon and radium are of note. While all actinides are radioactive, there are a lot of actinides or actinide-relating minerals in the Earth's crust such as uranium and thorium. These minerals are helpful in many ways, such as carbon-dating, most detectors, X-rays, and more. | 0 | Theoretical and Fundamental Chemistry |
An AFM probe has a sharp tip on the free-swinging end of a cantilever that protrudes from a holder. The dimensions of the cantilever are in the scale of micrometers. The radius of the tip is usually on the scale of a few nanometers to a few tens of nanometers. (Specialized probes exist with much larger end radii, for example probes for indentation of soft materials.) The cantilever holder, also called the holder chip—often 1.6 mm by 3.4 mm in size—allows the operator to hold the AFM cantilever/probe assembly with tweezers and fit it into the corresponding holder clips on the scanning head of the atomic force microscope.
This device is most commonly called an "AFM probe", but other names include "AFM tip" and "cantilever" (employing the name of a single part as the name of the whole device). An AFM probe is a particular type of SPM (scanning probe microscopy) probe.
AFM probes are manufactured with MEMS technology. Most AFM probes used are made from silicon (Si), but borosilicate glass and silicon nitride are also in use. AFM probes are considered consumables as they are often replaced when the tip apex becomes dull or contaminated or when the cantilever is broken. They can cost from a couple of tens of dollars up to hundreds of dollars per cantilever for the most specialized cantilever/probe combinations.
Just the tip is brought very close to the surface of the object under investigation, the cantilever is deflected by the interaction between the tip and the surface, which is what the AFM is designed to measure. A spatial map of the interaction can be made by measuring the deflection at many points on a 2D surface.
Several types of interaction can be detected. Depending on the interaction under investigation, the surface of the tip of the AFM probe needs to be modified with a coating. Among the coatings used are gold – for covalent bonding of biological molecules and the detection of their interaction with a surface, diamond for increased wear resistance and magnetic coatings for detecting the magnetic properties of the investigated surface. Another solution exists to achieve high resolution magnetic imaging : having the probe equip with a microSQUID. The AFM tips is fabricated using silicon micro machining and the precise positioning of the microSQUID loop is done by electron beam lithography. The additional attachment of a quantum dot to the tip apex of a conductive probe enables surface potential imaging with high lateral resolution, scanning quantum dot microscopy.
The surface of the cantilevers can also be modified. These coatings are mostly applied in order to increase the reflectance of the cantilever and to improve the deflection signal. | 0 | Theoretical and Fundamental Chemistry |
These are liquid solutions of one or more organic scintillators in an organic solvent. The typical solutes are fluors such as p-terphenyl (), PBD (), butyl PBD (), PPO (), and wavelength shifter such as POPOP (). The most widely used solvents are toluene, xylene, benzene, phenylcyclohexane, triethylbenzene, and decalin. Liquid scintillators are easily loaded with other additives such as wavelength shifters to match the spectral sensitivity range of a particular PMT, or B to increase the neutron detection efficiency of the scintillation counter itself (since B has a high interaction cross section with thermal neutrons). Newer approaches combine several solvents or load different metals to achieve identification of incident particles. For many liquids, dissolved oxygen can act as a quenching agent and lead to reduced light output, hence the necessity to seal the solution in an oxygen-free, airtight enclosure. | 0 | Theoretical and Fundamental Chemistry |
Tennant was born in Selby in Yorkshire. His father was Calvert Tennant (named after his grandmother Phyllis Calvert, a granddaughter of Cecilius Calvert, 2nd Baron Baltimore).
His own name derives from his grandmother Rebecca Smithson, widow of Joshua Hitchling. He attended Beverley Grammar School and there is a plaque over one of the entrances to the present school commemorating his discovery of the two elements, osmium and iridium.
He began to study medicine at Edinburgh in 1781, but after a few months moved to Cambridge, where he devoted himself to botany and chemistry.
He graduated M.D. at Cambridge in 1796, and about the same time purchased an estate near Cheddar, where he carried out agricultural experiments.
He was appointed professor of chemistry at Cambridge in 1813, but lived to deliver only one course of lectures, being killed near Boulogne-sur-Mer by the fall of a bridge over which he was riding. | 1 | Applied and Interdisciplinary Chemistry |
* Journal of Photochemistry and Photobiology [https://www.sciencedirect.com/journal/journal-of-photochemistry-and-photobiology]
* ChemPhotoChem [https://chemistry-europe.onlinelibrary.wiley.com/journal/23670932]
* Photochemistry and Photobiology [https://onlinelibrary.wiley.com/journal/17511097]
* Photochemical & Photobiological Sciences [https://www.springer.com/journal/43630]
* Photochemistry [https://www.mdpi.com/journal/molecules/sections/photochemistry] | 0 | Theoretical and Fundamental Chemistry |
Pure calcium carbide is a colourless solid. The common crystalline form at room temperature is a distorted rock-salt structure with the C</sup> units lying parallel. There are three different polymorphs which appear at room temperature: the tetragonal structure and two different monoclinic structures. | 1 | Applied and Interdisciplinary Chemistry |
Leonardo da Vinci designed a sprinkler system in the 15th century. Leonardo automated his patron's kitchen with a super-oven and a system of conveyor belts. In a comedy of errors, everything went wrong during a huge banquet, and a fire broke out. "The sprinkler system worked all too well, causing a flood that washed away all the food and a good part of the kitchen."
Ambrose Godfrey created the first successful automated sprinkler system in 1723. He used gunpowder to release a tank of extinguishing fluid.
The world's first modern recognizable sprinkler system was installed in the Theatre Royal, Drury Lane in the United Kingdom in 1812 by its architect, William Congreve, and was covered by patent No. 3606 dated the same year. The apparatus consisted of a cylindrical airtight reservoir of 400 hogsheads (c. 95,000 litres) fed by a water main which branched to all parts of the theatre. A series of smaller pipes fed from the distribution pipe were pierced with a series of holes which would pour water in the event of a fire.
Frederick Grinnell improved Henry S. Parmalee's design and in 1881 patented the automatic sprinkler that bears his name. He continued to improve the device and in 1890 invented the glass disc sprinkler, essentially the same as that in use today.
"Until the 1940s, sprinklers were installed almost exclusively for the protection of commercial buildings, whose owners were generally able to recoup their expenses with savings in insurance costs. Over the years, fire sprinklers have become mandatory safety equipment" in some parts of North America, in certain occupancies, including, but not limited to newly constructed "hospitals, schools, hotels and other public buildings", subject to the local building codes and enforcement. However, outside of the US and Canada, sprinklers have rarely been mandated by building codes for normal hazard occupancies which do not have large numbers of occupants (e.g. factories, process lines, retail outlets, petrol stations, etc.)
Sprinklers are now commonly installed in non-industrial buildings, including schools and residential premises. This is largely as a result of lobbying by the National Fire Sprinkler Network, the European Fire Sprinkler Network, and the British Automatic Fire Sprinkler Association. | 1 | Applied and Interdisciplinary Chemistry |
Lipids (oleaginous) are chiefly fatty acid esters, and are the basic building blocks of biological membranes. Another biological role is energy storage (e.g., triglycerides). Most lipids consist of a polar or hydrophilic head (typically glycerol) and one to three non polar or hydrophobic fatty acid tails, and therefore they are amphiphilic. Fatty acids consist of unbranched chains of carbon atoms that are connected by single bonds alone (saturated fatty acids) or by both single and double bonds (unsaturated fatty acids). The chains are usually 14-24 carbon groups long, but it is always an even number.
For lipids present in biological membranes, the hydrophilic head is from one of three classes:
* Glycolipids, whose heads contain an oligosaccharide with 1-15 saccharide residues.
* Phospholipids, whose heads contain a positively charged group that is linked to the tail by a negatively charged phosphate group.
* Sterols, whose heads contain a planar steroid ring, for example, cholesterol.
Other lipids include prostaglandins and leukotrienes which are both 20-carbon fatty acyl units synthesized from arachidonic acid.
They are also known as fatty acids | 0 | Theoretical and Fundamental Chemistry |
An RBS instrument generally includes three essential components:
* An ion source, usually alpha particles (He ions) or, less commonly, protons.
* A linear particle accelerator capable of accelerating incident ions to high energies, usually in the range 1-3 MeV.
* A detector capable of measuring the energies of backscattered ions over some range of angles.
Two common source/acceleration arrangements are used in commercial RBS systems, working in either one or two stages. One-stage systems consist of a He source connected to an acceleration tube with a high positive potential applied to the ion source, and the ground at the end of the acceleration tube. This arrangement is simple and convenient, but it can be difficult to achieve energies of much more than 1 MeV due to the difficulty of applying very high voltages to the system.
Two-stage systems, or "tandem accelerators", start with a source of He ions and position the positive terminal at the center of the acceleration tube. A stripper element included in the positive terminal removes electrons from ions which pass through, converting He ions to He ions. The ions thus start out being attracted to the terminal, pass through and become positive, and are repelled until they exit the tube at ground. This arrangement, though more complex, has the advantage of achieving higher accelerations with lower applied voltages: a typical tandem accelerator with an applied voltage of 750 kV can achieve ion energies of over 2 MeV.
Detectors to measure backscattered energy are usually silicon surface barrier detectors, a very thin layer (100 nm) of P-type silicon on an N-type substrate forming a p-n junction. Ions which reach the detector lose some of their energy to inelastic scattering from the electrons, and some of these electrons gain enough energy to overcome the band gap between the semiconductor valence and conduction bands. This means that each ion incident on the detector will produce some number of electron-hole pairs which is dependent on the energy of the ion. These pairs can be detected by applying a voltage across the detector and measuring the current, providing an effective measurement of the ion energy. The relationship between ion energy and the number of electron-hole pairs produced will be dependent on the detector materials, the type of ion and the efficiency of the current measurement; energy resolution is dependent on thermal fluctuations. After one ion is incident on the detector, there will be some dead time before the electron-hole pairs recombine in which a second incident ion cannot be distinguished from the first.
Angular dependence of detection can be achieved by using a movable detector, or more practically by separating the surface barrier detector into many independent cells which can be measured independently, covering some range of angles around direct (180 degrees) back-scattering. Angular dependence of the incident beam is controlled by using a tiltable sample stage. | 0 | Theoretical and Fundamental Chemistry |
The amplification reaction initiates when multiple primer hexamers anneal to the template. When DNA synthesis proceeds to the next starting site, the polymerase displaces the newly produced DNA strand and continues its strand elongation. The strand displacement generates a newly synthesized single-stranded DNA template for more primers to anneal. Further primer annealing and strand displacement on the newly synthesized template results in a hyper-branched DNA network. The sequence debranching during amplification results in a high yield of the products. To separate the DNA branching network, S1 nucleases are used to cleave the fragments at displacement sites. The nicks on the resulting DNA fragments are repaired by DNA polymerase I. | 1 | Applied and Interdisciplinary Chemistry |
To estimate the surface energy of a pure, uniform material, an individual region of the material can be modeled as a cube. In order to move a cube from the bulk of a material to the surface, energy is required. This energy cost is incorporated into the surface energy of the material, which is quantified by:
where and are coordination numbers corresponding to the surface and the bulk regions of the material, and are equal to 5 and 6, respectively; is the surface area of an individual molecule, and is the pairwise intermolecular energy.
Surface area can be determined by squaring the cube root of the volume of the molecule:
Here, corresponds to the molar mass of the molecule, corresponds to the density, and is the Avogadro constant.
In order to determine the pairwise intermolecular energy, all intermolecular forces in the material must be broken. This allows thorough investigation of the interactions that occur for single molecules. During sublimation of a substance, intermolecular forces between molecules are broken, resulting in a change in the material from solid to gas. For this reason, considering the enthalpy of sublimation can be useful in determining the pairwise intermolecular energy. Enthalpy of sublimation can be calculated by the following equation:
Using empirically tabulated values for enthalpy of sublimation, it is possible to determine the pairwise intermolecular energy. Incorporating this value into the surface energy equation allows for the surface energy to be estimated.
The following equation can be used as a reasonable estimate for surface energy: | 0 | Theoretical and Fundamental Chemistry |
The Journal of Thermal Analysis and Calorimetry is a bimonthly peer-reviewed scientific journal published by Springer Science+Business Media on behalf of Akadémiai Kiadó. It was established in 1969 as the Journal of Thermal Analysis, obtaining its current title in 1998. The journal covers all aspects of calorimetry, thermal analysis, and experimental thermodynamics. The editor-in-chief is I.M. Szilágyi (Budapest University of Technology and Economics). | 0 | Theoretical and Fundamental Chemistry |
Highly crosslinked resins typically swell much less than the latter. The property that allows these types of resins to work efficiently lies in their porous properties. The reacting compound can diffuse through the porous layer of the resin to converge with the scavenger's functional group. These types of resins are utilized in situations where swelling of the resins may cause a physical barrier to reaction purification. Contain much higher content of divinylbenzene. | 0 | Theoretical and Fundamental Chemistry |
* MicroMSI is endorsed by the NGA.
* Opticks is an open-source remote sensing application.
* Multispec is freeware multispectral analysis software.
* Gerbil is open source multispectral visualization and analysis software. | 0 | Theoretical and Fundamental Chemistry |
Förster resonance energy transfer efficiency () is the quantum yield of the energy-transfer transition, i.e. the probability of the energy-transfer event occurring per donor excitation event:
where
* is the rate of energy transfer,
* the radiative decay rate (fluorescence) of the donor,
* are non-radiative relaxation rates (e.g., internal conversion, intersystem crossing, external conversion etc.). | 0 | Theoretical and Fundamental Chemistry |
Different types of radioactive decay are characterized by their changes in mass number as well as atomic number, according to the radioactive displacement law of Fajans and Soddy.
For example, uranium-238 usually decays by alpha decay, where the nucleus loses two neutrons and two protons in the form of an alpha particle. Thus the atomic number and the number of neutrons each decrease by 2 (Z: 92 → 90, N: 146 → 144), so that the mass number decreases by 4 (A = 238 → 234); the result is an atom of thorium-234 and an alpha particle ():
On the other hand, carbon-14 decays by beta decay, whereby one neutron is transmuted into a proton with the emission of an electron and an antineutrino. Thus the atomic number increases by 1 (Z: 6 → 7) and the mass number remains the same (A = 14), while the number of neutrons decreases by 1 (N: 8 → 7). The resulting atom is nitrogen-14, with seven protons and seven neutrons:
Beta decay is possible because different isobars have mass differences on the order of a few electron masses. If possible, a nuclide will undergo beta decay to an adjacent isobar with lower mass. In the absence of other decay modes, a cascade of beta decays terminates at the isobar with the lowest atomic mass.
Another type of radioactive decay without change in mass number is emission of a gamma ray from a nuclear isomer or metastable excited state of an atomic nucleus. Since all the protons and neutrons remain in the nucleus unchanged in this process, the mass number is also unchanged. | 0 | Theoretical and Fundamental Chemistry |
Practical engineering designs must first take into account safety as the primary goal. All designs should incorporate passive cooling in combination with refractory materials to prevent melting and reconfiguration of fissionables into geometries capable of un-intentional criticality. Blanket layers of Lithium bearing compounds will generally be included as part of the design to generate Tritium to allow the system to be self-supporting for one of the key fuel element components. Tritium, because of its relatively short half-life and extremely high radioactivity, is best generated on-site to obviate the necessity of transportation from a remote location. D-T fuel can be manufactured on-site using Deuterium derived from heavy water production and Tritium generated in the hybrid reactor itself. Nuclear spallation to generate additional neutrons can be used to enhance the fission output, with the caveat that this is a tradeoff between the number of neutrons (typically 20-30 neutrons per spallation event) against a reduction of the individual energy of each neutron. This is a consideration if the reactor is to use natural Thorium as a fuel. While high energy (0.17c) neutrons produced from fusion events are capable of directly causing fission in both Thorium and U, the lower energy neutrons produced by spallation generally cannot. This is a tradeoff that affects the mixture of fuels against the degree of spallation used in the design. | 0 | Theoretical and Fundamental Chemistry |
Potassium bifluoride is the inorganic compound with the formula . This colourless salt consists of the potassium cation () and the bifluoride anion (). The salt is used as an etchant for glass. Sodium bifluoride is related and is also of commercial use as an etchant as well as in cleaning products. | 0 | Theoretical and Fundamental Chemistry |
It is also possible to derive the Grashof number by physical definition of the number as follows:
However, above expression, especially the final part at the right hand side, is slightly different from Grashof number appearing in literature. Following dimensionally correct scale in terms of dynamic viscosity can be used to have the final form.
Writing above scale in Gr gives;
Physical reasoning is helpful to grasp the meaning of the number. On the other hand, following velocity definition can be used as a characteristic velocity value for making certain velocities nondimensional. | 1 | Applied and Interdisciplinary Chemistry |
Photo-methionine can be used to label recombinant proteins in Escherichia coli cells; though methionine in general is a rare amino acid so that means it could only give limited structural data. Nevertheless, photo-methionine was incorporated into Ca regulating protein calmodulin (CaM that was 17-kDa) that has nine methionines and studied via mass spectrometry (MS). What makes this method different is the use of mineral salts medium instead of DMEM (Dulbeccos Modified Eagle's Limiting Medium) or dialyzed fetal bovine serum for the incorporation into the cells. Using the mineral salt medium allowed the cells to be grown from the beginning in order to eliminate complicated steps with other protocols (incubating the cells in LB medium, followed by washing, and further incubating in the depleted medium), meaning that photo-methionine could be incorporated at the very beginning of the cell growth that had a high yield above 30%. Photo-methionine had shown no damage during the cell growth process and once photo-activated by UV-A light, CaM had nine distinct cross-link sites once MS had determined there was peaks of photo-methionine labeled CaM. Not only can photo-methionine be used for mapping 3D protein structure, studying protein-protein interactions, but now hydrophobic regions in the protein. | 0 | Theoretical and Fundamental Chemistry |
The Watt steam engine design became synonymous with steam engines, and it was many years before significantly new designs began to replace the basic Watt design.
The first steam engines, introduced by Thomas Newcomen in 1712, were of the "atmospheric" design. At the end of the power stroke, the weight of the object being moved by the engine pulled the piston to the top of the cylinder as steam was introduced. Then the cylinder was cooled by a spray of water, which caused the steam to condense, forming a partial vacuum in the cylinder. Atmospheric pressure on the top of the piston pushed it down, lifting the work object. James Watt noticed that it required significant amounts of heat to warm the cylinder back up to the point where steam could enter the cylinder without immediately condensing. When the cylinder was warm enough that it became filled with steam the next power stroke could commence.
Watt realised that the heat needed to warm the cylinder could be saved by adding a separate condensing cylinder. After the power cylinder was filled with steam, a valve was opened to the secondary cylinder, allowing the steam to flow into it and be condensed, which drew the steam from the main cylinder causing the power stroke. The condensing cylinder was water cooled to keep the steam condensing. At the end of the power stroke, the valve was closed so the power cylinder could be filled with steam as the piston moved to the top. The result was the same cycle as Newcomen's design, but without any cooling of the power cylinder which was immediately ready for another stroke.
Watt worked on the design over a period of several years, introducing the condenser, and introducing improvements to practically every part of the design. Notably, Watt performed a lengthy series of trials on ways to seal the piston in the cylinder, which considerably reduced leakage during the power stroke, preventing power loss. All of these changes produced a more reliable design which used half as much coal to produce the same amount of power.
The new design was introduced commercially in 1776, with the first example sold to the Carron Company ironworks. Watt continued working to improve the engine, and in 1781 introduced a system using a sun and planet gear to turn the linear motion of the engines into rotary motion. This made it useful not only in the original pumping role, but also as a direct replacement in roles where a water wheel would have been used previously. This was a key moment in the industrial revolution, since power sources could now be located anywhere instead of, as previously, needing a suitable water source and topography. Watts partner Matthew Boulton began developing a multitude of machines that made use of this rotary power, developing the first modern industrialized factory, the Soho Foundry, which in turn produced new steam engine designs. Watts early engines were like the original Newcomen designs in that they used low-pressure steam, and all of the power was produced by atmospheric pressure. When, in the early 1800s, other companies introduced high-pressure steam engines, Watt was reluctant to follow suit due to safety concerns. Wanting to improve on the performance of his engines, Watt began considering the use of higher-pressure steam, as well as designs using multiple cylinders in both the double-acting concept and the multiple-expansion concept. These double-acting engines required the invention of the parallel motion, which allowed the piston rods of the individual cylinders to move in straight lines, keeping the piston true in the cylinder, while the walking beam end moved through an arc, somewhat analogous to a crosshead in later steam engines. | 0 | Theoretical and Fundamental Chemistry |
The alloy contains about 35–50% uranium and 1.5–4.0% carbon. At least two intermetallic compounds of iron and uranium were identified: UFe and UFe. Small amounts of uranium can drastically lower the melting point of iron and vice versa. reportedly melts at 1230 °C, at 805 °C; a mixture of these two can have melting point as low as 725 °C, a mixture of iron and can have melting point of 1055 °C. As ferrouranium readily dissolves in mineral acids, its chemical analysis is not problematic. | 1 | Applied and Interdisciplinary Chemistry |
It is possible by bond valence calculations to estimate how great a contribution a given oxygen atom is making to the assumed valence of uranium. Zachariasen lists the parameters to allow such calculations to be done for many of the actinides. Bond valence calculations use parameters which are estimated after examining a large number of crystal structures of uranium oxides (and related uranium compounds); note that the oxidation states which this method provides are only a guide which assists in the understanding of a crystal structure.
For uranium binding to oxygen the constants R and B are tabulated in the table below. For each oxidation state use the parameters from the table shown below. | 0 | Theoretical and Fundamental Chemistry |
Prior to the Montreal Protocol, large quantities of carbon tetrachloride were used to produce the chlorofluorocarbon refrigerants R-11 (trichlorofluoromethane) and R-12 (dichlorodifluoromethane). However, these refrigerants play a role in ozone depletion and have been phased out. Carbon tetrachloride is still used to manufacture less destructive refrigerants. | 1 | Applied and Interdisciplinary Chemistry |
* EIA/JEDEC Standard EIA/JESD61: Isothermal Electromigration Test Procedure.
* EIA/JEDEC Standard EIA/JESD63: Standard method for calculating the electromigration model parameters for current density and temperature.
* [https://www.ifte.de/books/em/em_chap2.pdf Fundamentals of electromigration, Chapter 2] | 0 | Theoretical and Fundamental Chemistry |
A large research effort involves approaches to know whether proteins have binding sites which are specific for particular lipids and whether the protein–lipid complexes can be considered to be long-lived, on the order of the time required for the turnover a typical enzyme, that is 10 sec. This is now known through the use of H-NMR, ESR, and fluorescent methods.
There are two approaches used to measure the relative affinity of lipids binding to specific membrane proteins. These involve the use of lipid analogues in reconstituted phospholipid vesicles containing the protein of interest:
1) Spin-labeled phospholipids are motionally restricted when they are adjacent to membrane proteins. The result is a component in the ESR spectrum which is broadened. The experimental spectrum can be analyzed as the sum of the two components, a rapidly tumbling species in the "bulk" lipid phase with a sharp spectrum, and a motionally restricted component adjacent to the protein. Membrane protein denaturation causes further broadening of ESR spin label spectrum and throws more light on membrane lipid-proteins interactions
2) Spin-labeled and brominated lipid derivatives are able to quench the intrinsic tryptophan fluorescence from membrane proteins. The efficiency of quenching depends on the distance between the lipid derivative and the fluorescent tryptophans. | 1 | Applied and Interdisciplinary Chemistry |
R-410A was invented and patented by Allied Signal (now Honeywell) in 1991. Other producers around the world have been licensed to manufacture and sell R-410A, but Honeywell continues to be the leader in capacity and sales. R-410A was successfully commercialized in the air conditioning segment by a combined effort of Carrier Corporation, Emerson Climate Technologies, Inc., Copeland Scroll Compressors (a division of Emerson Electric Company), and Allied Signal. Carrier Corporation was the first company to introduce an R-410A-based residential air conditioning unit into the market in 1996 and holds the trademark "Puron". | 1 | Applied and Interdisciplinary Chemistry |
Emmerling conducted post-doctoral research in the group of Prof. Claudia Felser at Johannes Gutenberg University in Mainz. In 2005, Emmerling moved to the Federal Institute for Materials Research and Testing (BAM) in Berlin as head of the working group on X-ray structure analysis. From 2010 until 2013 she held a guest professorship in inorganic chemistry at Humboldt University in Berlin. In 2012 Emmerling became Head of the Division ‘Structure Analysis’ at BAM, before becoming Head of Department Analytical Sciences and Reference Materials in 2017.
Emmerling achieved her habilitation in chemistry in 2018 focusing on in situ analysis of mechanochemical reaction.
The current work of Emmerling focuses on the investigation of crystallization and aggregation phenomena by means of synchrotron radiation. She is also well known for her advances in mechanochemistry and for developing new methods to monitor mechanochemical reactions in situ. Emmerling develops and uses time-resolved experiments applying synchrotron X-rays, supplemented with additional analytic methods including Raman spectroscopy and XANES.
In 2019, Emmerling was elected as a member of the Analytical Chemistry Division of the International Union of Pure and Applied Chemistry (IUPAC) Currently, she is Head of Materials Cheimstry Department and Head of the Structure Analysis Division at the German Federal Institute for Materials Research and Testing (BAM). | 0 | Theoretical and Fundamental Chemistry |
One of the most common forms of pesticide application, especially in conventional agriculture, is the use of mechanical sprayers. Hydraulic sprayers consists of a tank, a pump, a lance (for single nozzles) or boom, and a nozzle (or multiple nozzles). Sprayers convert a pesticide formulation, often containing a mixture of water (or another liquid chemical carrier, such as fertilizer) and chemical, into droplets, which can be large rain-type drops or tiny almost-invisible particles. This conversion is accomplished by forcing the spray mixture through a spray nozzle under pressure. The size of droplets can be altered through the use of different nozzle sizes, or by altering the pressure under which it is forced, or a combination of both. Large droplets have the advantage of being less susceptible to spray drift, but require more water per unit of land covered. Due to static electricity, small droplets are able to maximize contact with a target organism, but very still wind conditions are required. | 1 | Applied and Interdisciplinary Chemistry |
IgA - IgE receptor - IGF type 1 receptor - IGF type 2 receptor - IgG - IgM - immediate-early protein - immune cell - immune system - immunoglobulin - immunoglobulin joining region - immunoglobulin variable region - immunologic receptor - immunology - In vivo - infrared spectroscopy - inhibin - inhibitor - inhibitory gi G-protein - Inorganic chemistry - insect protein - Insulin - insulin receptor - insulin-like growth factor I - Integral membrane protein - intein - intercellular adhesion molecule-1 - interferon receptor - interferon type I - interferon type II - interferon-alpha - interferon-beta - interleukin receptor - interleukin-1 receptor - interleukin-2 receptor - interleukin-3 - interleukin-3 receptor - intermediate filament - intermediate filament protein - intermembrane space - Intermolecular force - International Union of Pure and Applied Chemistry (IUPAC) - interphase - intracisternal A-particle gene - Intramolecular force - intron - Inverse agonist - invertebrate peptide receptor - invertebrate photoreceptor - Ion channel - ion channel gating - Ionic bond - ionization potential - iron–sulfur protein - isoenzyme - isoleucine - Isomer - Isothermal titration calorimeter - Isotopic tracer | 1 | Applied and Interdisciplinary Chemistry |
Anti-graffiti coatings can be invisible to the naked eye. There are two different categories of anti-graffiti coatings. The first, sacrificial coatings, are applied to a surface and then removed when graffiti is applied. The surface underneath will be left clean and a new sacrificial coating can be applied. The other type of coating are permanent coatings that prevent graffiti from adhering to a surface in the first place.
Newer coatings are made of charged polymeric materials that form a gel on the surface of the building or substrate. Some of the most important characteristics of anti-graffiti coatings are:
* Sufficient adherence without damage to substrates
* Hydrophobicity (water repellence)
* Environmentally friendly composition and processing
* Resistance to UV aging and weathering
* Good cleaning efficiency | 0 | Theoretical and Fundamental Chemistry |
Binders promote the binding of pigment particles between themselves and the coating layer of the paper. Binders are spherical particles less than 1 µm in diameterr. Common binders are styrene maleic anhydride copolymer or styrene-acrylate copolymer. The surface chemical composition is differentiated by the adsorption of acrylic acid or an anionic surfactant, both of which are used for stabilization of the dispersion in water. Co-binders, or thickeners, are generally water-soluble polymers that influence the paper's color viscosity, water retention, sizing, and gloss. Some common examples are carboxymethyl cellulose (CMC), cationic and anionic hydroxyethyl cellulose (EHEC), modified starch, and dextrin. | 0 | Theoretical and Fundamental Chemistry |
A peptide library is a tool for studying proteins. Peptide libraries typically contain a large number of peptides that have a systematic combination of amino acids. Usually, solid phase synthesis, e.g. resin as a flat surface or beads, is used for peptide library generation. Peptide libraries are a popular tool for experiments in drug design, protein–protein interactions, and other biochemical and pharmaceutical applications.
Synthetic peptide libraries are synthesized without utilizing biological systems such as phage or in vitro translation. There are at least five subtypes of synthetic peptide libraries that differ from each other by the design of the library and/or the method used for the synthesis of the library. The subtypes include:
* Overlapping peptide libraries - in which the entirety of a larger protein is used to produce a library of 8-20 amino acid peptides which overlap; these libraries can be used to identify the specific regions of a larger protein which participate in a given interaction or to provide pre-digested versions of a larger protein for binding.
* Truncation peptide libraries - in which a given peptide is produced with various or all N or C terminal truncations, these smaller fragments can be used to identify the minimal required region of a peptide for a given interaction being studied.
* Random libraries - randomly generated peptides of a set length, or range of lengths, can be used to identify novel binding partners of a target of interest.
* Alanine scanning libraries - in which each amino acid of a given protein or peptide is replaced with an alanine sequentially such that each peptide contains only one alanine mutations but all possible mutations to alanine are present; this can be used to identify critical residues for binding
* Positional or scrambled peptide libraries - in which specific positions in the peptide are substituted for many or all other amino acids such that the affect of each amino acid at that position in the peptide on the binding or other activity of the peptide can be tested. Scrambled libraries are often random peptides and used as negative controls.
Solid phase peptide synthesis is limited to a peptide chain length of approximately 70 amino acids and is generally unsuitable for the study of larger proteins. Many libraries utilize peptide chains much shorter than 70 amino acids. For 20 encoded amino acids at maximally 70 positions, this results in an upper limit of 20, or more than 10 quindecillion (1x10), possible combinations, not accounting for the potential use of amino acids with post-translational modifications or amino acids not encoded in the genetic code, such as selenocysteine and pyrrolysine. Peptide libraries generally encompass only a fraction of this diversity, selected for depending on the needs of the experiment, for instance keeping some amino acids constant at certain positions.
Large random peptide libraries are often used for the synthesis of certain peptide molecules, such as ultra-large chemical libraries for the discovery of high-affinity peptide binders. Any increase in the library size severely affects parameters, such as the synthesis scale, the number of library members, the sequence deconvolution and peptide structure elucidation. To mitigate these technical challenges, an algorithm-supported approach to peptide library design may use molecular mass and amino acid diversity to simplify the laborious permutation identification in complex mixtures when using mass spectrometry. This approach is used to avoid mass redundancy.
Biological reagent companies, such as Pepscan, ProteoGenix, Mimotopes, GenScript and many others, manufacture customized peptide libraries. | 1 | Applied and Interdisciplinary Chemistry |
In her final year at the University of Glasgow, Hitchins began to work with Frederick Soddy. When he moved to the University of Aberdeen as the Chair of Chemistry in 1914, Hitchins and another assistant, John A. Cranston, accompanied him. At Aberdeen, Hitchins was a Carnegie Research Scholar, receiving a one-year appointment and monetary award given to a graduate of a Scottish institution for research and study by American philanthropist Andrew Carnegie.
Expectations that Soddy would establish a thriving research center at Aberdeen were disrupted by World War I, as male students became soldiers, and women students were encouraged to graduate from accelerated courses so as to fill positions in industry and government. Hitchins was drafted to work in the Admiralty Steel Analysis Laboratories in 1916. After the war, women workers were displaced from their jobs by returning soldiers. Hitchins, released from the Admiralty, was able to find work at a Sheffield steel works.
In 1921, Frederick Soddy, then at the University of Oxford, obtained funding to rehire Hitchins as a technical assistant. He had recently received the Nobel prize for his work on radioactivity and isotopes. In 1922, Hitchins became his private research assistant. She continued to work with him until 1927, when she emigrated to Kenya to be nearer to her family. | 0 | Theoretical and Fundamental Chemistry |
Papillomaviruses typically target epithelial cells and cause everything from warts to cervical cancer. When human papillomavirus (HPV) transforms a cell, it interferes with the function of cellular proteins while degrading other cellular proteins. | 1 | Applied and Interdisciplinary Chemistry |
Pulsatile secretion is a biochemical phenomenon observed in a wide variety of cell and tissue types, in which chemical products are secreted in a regular temporal pattern. The most common cellular products observed to be released in this manner are intercellular signaling molecules such as hormones or neurotransmitters. Examples of hormones that are secreted pulsatilely include insulin, thyrotropin, TRH, gonadotropin-releasing hormone (GnRH) and growth hormone (GH). In the nervous system, pulsatility is observed in oscillatory activity from central pattern generators. In the heart, pacemakers are able to work and secrete in a pulsatile manner. A pulsatile secretion pattern is critical to the function of many hormones in order to maintain the delicate homeostatic balance necessary for essential life processes, such as development and reproduction. Variations of the concentration in a certain frequency can be critical to hormone function, as evidenced by the case of GnRH agonists, which cause functional inhibition of the receptor for GnRH due to profound downregulation in response to constant (tonic) stimulation. Pulsatility may function to sensitize target tissues to the hormone of interest and upregulate receptors, leading to improved responses. This heightened response may have served to improve the animal's fitness in its environment and promote its evolutionary retention.
Pulsatile secretion in its various forms is observed in:
*Hypothalamic-pituitary-gonadal axis (HPG) related hormones
*Glucocorticoids
*Insulin
*Growth hormone
*Parathyroid hormone | 1 | Applied and Interdisciplinary Chemistry |
Non-linear kinematic wave for debris flow can be written as follows with complex non-linear coefficients:
where is the debris flow height, is the time, is the downstream channel position, is the pressure gradient and the depth dependent nonlinear variable wave speed, and is a flow height and pressure gradient dependent variable diffusion term.
This equation can also be written in the conservative form:
where is the generalized flux that depends on several physical and geometrical parameters of the flow, flow height and the hydraulic pressure gradient. For this equation reduces to the Burgers' equation. | 1 | Applied and Interdisciplinary Chemistry |
The concentrations of species in equilibrium are usually calculated under the assumption that activity coefficients are either known or can be ignored. In this case, each equilibrium constant for the formation of a complex in a set of multiple equilibria can be defined as follows
:α A + β B ... AB...;
The concentrations of species containing reagent A are constrained by a condition of mass-balance, that is, the total (or analytical) concentration, which is the sum of all species' concentrations, must be constant. There is one mass-balance equation for each reagent of the type
There are as many mass-balance equations as there are reagents, A, B..., so if the equilibrium constant values are known, there are n mass-balance equations in n unknowns, [A], [B]..., the so-called free reagent concentrations. Solution of these equations gives all the information needed to calculate the concentrations of all the species.
Thus, the importance of equilibrium constants lies in the fact that, once their values have been determined by experiment, they can be used to calculate the concentrations, known as the speciation, of mixtures that contain the relevant species. | 0 | Theoretical and Fundamental Chemistry |
Stainless steel forms a passivation layer of chromium(III) oxide. Similar passivation behavior occurs with magnesium, titanium, zinc, zinc oxides, aluminium, polyaniline, and other electroactive conductive polymers.
Special "weathering steel" alloys such as Cor-Ten rust at a much slower rate than normal, because the rust adheres to the surface of the metal in a protective layer. Designs using this material must include measures that avoid worst-case exposures since the material still continues to rust slowly even under near-ideal conditions. | 1 | Applied and Interdisciplinary Chemistry |
Chemical structures of BNA monomers containing a bridge at the 2, 4-position of the ribose to afford a 2, 4-BNA monomer as synthesized by Takeshi Imanishi's group. The nature of the bridge can vary for different types of monomers. The 3D structures for A-RNA and B-DNA were used as a template for the design of the BNA monomers. The goal for the design was to find derivatives that possess high binding affinities with complementary RNA and/or DNA strands.
An increased conformational inflexibility of the sugar moiety in nucleosides (oligonucleotides) results in a gain of high binding affinity with complementary single-stranded RNA and/or double-stranded DNA. The first 2,4-BNA (LNA) monomers were first synthesized by Takeshi Imanishis group in 1997 followed independently by Jesper Wengels group in 1998.
BNA nucleotides can be incorporated into DNA or RNA oligonucleotides at any desired position. Such oligomers are synthesized chemically and are now commercially available. The bridged ribose conformation enhances base stacking and pre-organizes the backbone of the oligonucleotide significantly increasing their hybridization properties.
The incorporation of BNAs into oligonucleotides allows the production of modified synthetic oligonucleotides with
equal or higher binding affinity against a DNA or RNA complement with excellent single-mismatch discriminating power;
better RNA selective binding;
stronger and more sequence selective triplex-forming characters;
pronounced higher nuclease resistance, even higher than Sp-phosphorothioate analogues; and
good aqueous solubility of the resulting oligonucleotides when compared to regular DNA or RNA oligonucleotides.
New BNA analogs introduced by Imanishis group were designed by taking the length of the bridged moiety into account. A six-membered bridged structure with a unique structural feature (N-O bond) in the sugar moiety was designed to have a nitrogen atom. This atom improves the formation of duplexes and triplexes by lowering the repulsion between the negatively charged backbone phosphates. These modifications allow to control the affinity towards complementary strands, regulate resistance against nuclease degradation and the synthesis of functional molecules designed for specific applications in genomics. The properties of these analogs were investigated and compared to those of previous 2,4-BNA (LNA) modified oligonucleotides by Imanishis group. Imanishis results show that "2,4'-BNA-modified oligonucleotides with these profiles show great promise for applications in antisense and antigene technologies." | 1 | Applied and Interdisciplinary Chemistry |
Autophagy is a self-degradative mechanism that regulates energy sources during growth and reaction to dietary stress. Autophagy also cleans up after itself, clearing aggregated proteins, cleaning damaged structures including mitochondria and endoplasmic reticulum and eradicating intracellular infections. Additionally, autophagy has antiviral and antibacterial roles within the cell, and it is involved at the beginning of distinctive and adaptive immune responses to viral and bacterial contamination. Some viruses include virulence proteins that prevent autophagy, while others utilize autophagy elements for intracellular development or cellular splitting. Macro autophagy, micro autophagy, and chaperon-mediated autophagy are the three basic types of autophagy. When macro autophagy is triggered, an exclusion membrane incorporates a section of the cytoplasm, generating the autophagosome, a distinctive double-membraned organelle. The autophagosome then joins the lysosome to create an autolysosome, with lysosomal enzymes degrading the components. In micro autophagy, the lysosome or vacuole engulfs a piece of the cytoplasm by invaginating or protruding the lysosomal membrane to enclose the cytosol or organelles. The chaperone-mediated autophagy (CMA) protein quality assurance by digesting oxidized and altered proteins under stressful circumstances and supplying amino acids through protein denaturation. Autophagy is the primary intrinsic degradative system for peptides, fats, carbohydrates, and other cellular structures. In both physiologic and stressful situations, this cellular progression is vital for upholding the correct cellular balance. Autophagy instability leads to a variety of illness symptoms, including inflammation, biochemical disturbances, aging, and neurodegenerative, due to its involvement in controlling cell integrity. The modification of the autophagy-lysosomal networks is a typical hallmark of many neurological and muscular illnesses. As a result, autophagy has been identified as a potential strategy for the prevention and treatment of various disorders. Many of these disorders are prevented or improved by consuming polyphenol in the meal. As a result, natural compounds with the ability to modify the autophagy mechanism are seen as a potential therapeutic option. The creation of the double membrane (phagophore), which would be known as nucleation, is the first step in macro-autophagy. The phagophore approach indicates dysregulated polypeptides or defective organelles that come from the cell membrane, Golgi apparatus, endoplasmic reticulum, and mitochondria. With the conclusion of the autophagocyte, the phagophore's enlargement comes to an end. The auto-phagosome combines with the lysosomal vesicles to formulate an auto-lysosome that degrades the encapsulated substances, referred to as phagocytosis. | 1 | Applied and Interdisciplinary Chemistry |
Tetraanthraporphyrin exhibit strongly red-shifted and hyperchromic absorption bands. The maximum of absorption is about 830 nm. The molar extinction coefficients reach 10 scale. Very strong red-shift of absorption by about 90 nm upon protonation of nitrogen atoms and blue-shift by 20−40 nm upon metal insertion are observed. | 1 | Applied and Interdisciplinary Chemistry |
The upcasting (up-casting, upstream, or upward casting) is a method of either vertical or horizontal continuous casting of rods and pipes of various profiles (cylindrical, square, hexagonal, slabs etc.) of 8-30mm in diameter. Copper (Cu), bronze (Cu·Sn alloy), nickel alloys are usually used because of greater casting speed (in case of vertical upcasting) and because of better physical features obtained. The advantage of this method is that metals are almost oxygen-free and that the rate of product crystallization (solidification) may be adjusted in a crystallizer - a high-temperature resistant device that cools a growing metal rod or pipe by using water.
The method is comparable to Czochralski method of growing silicon (Si) crystals, which is a metalloid. | 1 | Applied and Interdisciplinary Chemistry |
Electrolysis in an aqueous solution is a similar process as mentioned in electrolysis of water. However, it is considered to be a complex process because the contents in solution have to be analyzed in half reactions, whether reduced or oxidized. | 0 | Theoretical and Fundamental Chemistry |
In addition to crystallographic space groups there are also magnetic space groups (also called two-color (black and white) crystallographic groups or Shubnikov groups). These symmetries contain an element known as time reversal. They treat time as an additional dimension, and the group elements can include time reversal as reflection in it. They are of importance in magnetic structures that contain ordered unpaired spins, i.e. ferro-, ferri- or antiferromagnetic structures as studied by neutron diffraction. The time reversal element flips a magnetic spin while leaving all other structure the same and it can be combined with a number of other symmetry elements. Including time reversal there are 1651 magnetic space groups in 3D . It has also been possible to construct magnetic versions for other overall and lattice dimensions ([https://web.archive.org/web/20111119065722/http://www.bk.psu.edu/faculty/litvin/Download.html Daniel Litvin's papers], , ). Frieze groups are magnetic 1D line groups and layer groups are magnetic wallpaper groups, and the axial 3D point groups are magnetic 2D point groups. Number of original and magnetic groups by (overall, lattice) dimension: | 0 | Theoretical and Fundamental Chemistry |
In chemistry, folding is the process by which a molecule assumes its shape or conformation. The process can also be described as intramolecular self-assembly, a type of molecular self-assembly, where the molecule is directed to form a specific shape through noncovalent interactions, such as hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, pi-pi interactions, and electrostatic effects.
The most active area of interest in the folding of molecules is the process of protein folding, which analyses the specific sequences of amino acids in a protein. The shape of the folded protein can be used to understand its function and design drugs to influence the processes that it is involved in.
There is also a great deal of interest in the construction of artificial folding molecules or foldamers. They are studied as models of biological molecules and for potential application to the development of new functional materials. | 0 | Theoretical and Fundamental Chemistry |
Ions in crystal lattices of purely ionic compounds are spherical; however, if the positive ion is small and/or highly charged, it will distort the electron cloud of the negative ion, an effect summarised in Fajans' rules. This polarization of the negative ion leads to a build-up of extra charge density between the two nuclei, that is, to partial covalency. Larger negative ions are more easily polarized, but the effect is usually important only when positive ions with charges of 3+ (e.g., Al) are involved. However, 2+ ions (Be) or even 1+ (Li) show some polarizing power because their sizes are so small (e.g., LiI is ionic but has some covalent bonding present). Note that this is not the ionic polarization effect that refers to displacement of ions in the lattice due to the application of an electric field. | 0 | Theoretical and Fundamental Chemistry |
It is on the World Health Organization's List of Essential Medicines. The World Health Organization classifies cefalexin as highly important for human medicine. | 0 | Theoretical and Fundamental Chemistry |
A Townsend discharge can be sustained only over a limited range of gas pressure and electric field intensity. The accompanying plot shows the variation of voltage drop and the different operating regions for a gas-filled tube with a constant pressure, but a varying current between its electrodes. The Townsend avalanche phenomena occurs on the sloping plateau B-D. Beyond D the ionisation is sustained.
At higher pressures, discharges occur more rapidly than the calculated time for ions to traverse the gap between electrodes, and the streamer theory of spark discharge of Raether, Meek, and Loeb is applicable. In highly non-uniform electric fields, the corona discharge process is applicable. See Electron avalanche for further description of these mechanisms.
Discharges in vacuum require vaporization and ionisation of electrode atoms. An arc can be initiated without a preliminary Townsend discharge; for example when electrodes touch and are then separated. | 0 | Theoretical and Fundamental Chemistry |
Transcriptome analysis is the study of all the RNA transcripts that are produced by the genome of an organism. Linked-read sequencing has been used by researchers to assemble transcript isoforms and alternative splicing events. Information regarding alternative splicing events can provide insights into the regulation of gene expression in human transcriptome | 1 | Applied and Interdisciplinary Chemistry |
Chemical measures of water quality include dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total dissolved solids (TDS), pH, nutrients (nitrates and phosphorus), heavy metals, soil chemicals (including copper, zinc, cadmium, lead and mercury), and pesticides. | 1 | Applied and Interdisciplinary Chemistry |
The second phase of the $170 million Human Microbiome Project was focused on integrating patient data to different omic datasets, considering host genetics, clinical information and microbiome composition. The phase one focused on characterization of communities in different body sites. Phase 2 focused in the integration of multiomic data from host & microbiome to human diseases. Specifically, the project used multiomics to improve the understanding of the interplay of gut and nasal microbiomes with type 2 diabetes, gut microbiomes and inflammatory bowel disease and vaginal microbiomes and pre-term birth. | 1 | Applied and Interdisciplinary Chemistry |
In medicine, this property is used to create droppers and IV infusion sets which have a standardized diameter, in such a way that 1 millilitre is equivalent to 20 drops. When smaller amounts are necessary (such as paediatrics), microdroppers or paediatric infusion sets are used, in which 1 millilitre = 60 microdrops. | 1 | Applied and Interdisciplinary Chemistry |
As in many other systems, vortices can exist in BECs.
Vortices can be created, for example, by "stirring" the condensate with lasers,
rotating the confining trap,
or by rapid cooling across the phase transition.
The vortex created will be a quantum vortex with core shape determined by the interactions. Fluid circulation around any point is quantized due to the single-valued nature of the order BEC order parameter or wavefunction, that can be written in the form where and are as in the cylindrical coordinate system, and is the angular quantum number (a.k.a. the "charge" of the vortex). Since the energy of a vortex is proportional to the square of its angular momentum, in trivial topology only vortices can exist in the steady state; Higher-charge vortices will have a tendency to split into vortices, if allowed by the topology of the geometry.
An axially symmetric (for instance, harmonic) confining potential is commonly used for the study of vortices in BEC. To determine , the energy of must be minimized, according to the constraint . This is usually done computationally, however, in a uniform medium, the following analytic form demonstrates the correct behavior, and is a good approximation:
Here, is the density far from the vortex and , where is the healing length of the condensate.
A singly charged vortex () is in the ground state, with its energy given by
where is the farthest distance from the vortices considered.(To obtain an energy which is well defined it is necessary to include this boundary .)
For multiply charged vortices () the energy is approximated by
which is greater than that of singly charged vortices, indicating that these multiply charged vortices are unstable to decay. Research has, however, indicated they are metastable states, so may have relatively long lifetimes.
Closely related to the creation of vortices in BECs is the generation of so-called dark solitons in one-dimensional BECs. These topological objects feature a phase gradient across their nodal plane, which stabilizes their shape even in propagation and interaction. Although solitons carry no charge and are thus prone to decay, relatively long-lived dark solitons have been produced and studied extensively. | 0 | Theoretical and Fundamental Chemistry |
Most tests will incorporate a second line which contains a further antibody (one which is not specific to the analyte) that binds some of the remaining colored particles which did not bind to the test line. This confirms that fluid has passed successfully from the sample-application pad, past the test line. By giving confirmation that the sample has had a chance to interact with the test line, this increases confidence that a visibly-unchanged test line can be interpreted as a negative result (or that a changed test line can be interpreted as a negative result in a competitive assay). | 1 | Applied and Interdisciplinary Chemistry |
Donna M. Huryn is an American medicinal and organic chemist. She received her B.A. (chemistry) from Cornell University, and Ph.D. in organic chemistry from the University of Pennsylvania. She is on the faculty at the University of Pittsburgh’s school of pharmacy, holds an adjunct appointment in the department of chemistry at the University of Pennsylvania, is the principal investigator of the University of Pittsburgh Chemical Diversity Center, and was a visiting fellow in the summer of 2017 at the University of Bologna. She is a fellow of the American Chemical Society, recipient of the ACS Philadelphia Local Section Award, has held a number of elected positions within the American Chemical Society at both the local and national levels, and is 2015 Chair of the Division of Organic Chemistry. Huryn also formed, along with a number of other scientists, the Empowering Women in Organic Chemistry Conferences in 2019. The goal was to empower and bring the research and career of all marginalized individuals in chemistry-related fields to the forefront of the scientific community. Huryn noticed how there was not enough women pursuing and maintaining a career in organic chemistry, and thus founded this organization. The Empowering Women in Organic Chemistry Conferences allowed for women leaders to present their scientific findings and hear the stories of how eminent women in the field of organic chemistry overcame the challenges they faced being female. She is associate editor of ACS Medicinal Chemistry Letters. She in also an editor of the journal Organic Reactions and co-authored the textbook Medicinal Chemistry and the article "Medicinal Chemistry: Where Are All the Women?" which appeared in the ACS Medicinal Chemistry Letters Journal. Huryn’s research focuses on the design and synthesis of small molecules probes and drugs to treat cancer, neurodegenerative and infectious diseases. | 0 | Theoretical and Fundamental Chemistry |
Defined by the monoclonal antibody MBr1, Globo H has been isolated from breast cancer cell line MCF-7, and its structure has been determined through several analyses, including NMR spectroscopy and methylation analysis. Globo H consists of a hexasaccharide of the structure Fucα(1-2)Galβ(1-3)GalNAcβ(1-3)Galα(1-4)Galβ(1-4)Glcβ(1) with a ceramide attached to its terminal glucose ring at the 1 position in a beta linkage. | 1 | Applied and Interdisciplinary Chemistry |
The lipid pump sequesters carbon from the oceans surface to deeper waters via lipids associated with overwintering vertically migratory zooplankton. Lipids are a class of hydrocarbon rich, nitrogen and phosphorus deficient compounds essential for cellular structures. The lipid associated carbon enters the deep ocean as carbon dioxide produced by respiration of lipid reserves and as organic matter from the mortality of zooplankton. Compared to the more general biological pump, the lipid pump also results in a lipid shunt, where other nutrients like nitrogen and phosphorus that are consumed in excess must be excreted back to the surface environment, and thus are not removed from the surface mixed layer of the ocean. This means that the carbon transported by the lipid pump does not limit the availability of essential nutrients in the ocean surface. Carbon sequestration via the lipid pump is therefore decoupled from nutrient removal, allowing carbon uptake by oceanic primary production to continue. In the Biological Pump, nutrient removal is always coupled to carbon sequestration; primary production is limited as carbon and nutrients are transported to depth together in the form of organic matter. The contribution of the lipid pump to the sequestering of carbon in the deeper waters of the ocean can be substantial: the carbon transported below 1,000 metres (3,300 ft) by copepods of the genus Calanus' in the Arctic Ocean almost equals that transported below the same depth annually by particulate organic carbon (POC) in this region. A significant fraction of this transported carbon would not return to the surface due to respiration and mortality. Research is ongoing to more precisely estimate the amount that remains at depth. The export rate of the lipid pump may vary from 1–9.3 g C m y across temperate and subpolar regions containing seasonally-migrating zooplankton. The role of zooplankton, and particularly copepods, in the food web is crucial to the survival of higher trophic level organisms whose primary source of nutrition is copepods. With warming oceans and increasing melting of ice caps due to climate change, the organisms associated with the lipid pump may be affected, thus influencing the survival of many commercially important fish and endangered marine mammals. As a new and previously unquantified component of oceanic carbon sequestration, further research on the lipid pump can improve the accuracy and overall understanding of carbon fluxes in global oceanic systems. | 0 | Theoretical and Fundamental Chemistry |
Epimerization is a chemical process where an epimer is converted to its diastereomeric counterpart. It can happen in condensed tannins depolymerization reactions. Epimerization can be spontaneous (generally a slow process), or catalysed by enzymes, e.g. the epimerization between the sugars N-acetylglucosamine and N-acetylmannosamine, which is catalysed by renin-binding protein.
The penultimate step in Zhang & Trudells classic epibatidine synthesis is an example of epimerization. Pharmaceutical examples include epimerization of the erythro isomers of methylphenidate to the pharmacologically preferred and lower-energy threo isomers, and undesired in vivo' epimerization of tesofensine to brasofensine. | 0 | Theoretical and Fundamental Chemistry |
The Warburg coefficient (or Warburg constant; denoted or ) is the diffusion coefficient of ions in solution, associated to the Warburg element, . The Warburg coefficient has units of
The value of can be obtained by the gradient of the Warburg plot, a linear plot of the real impedance () against the reciprocal of the square root of the frequency (). This relation should always yield a straight line, as it is unique for a Warburg.
Alternatively, the value of can be found by:
where
* is the ideal gas constant;
* is the thermodynamic temperature;
* is the Faraday constant;
* is the valency;
* is the diffusion coefficient of the species, where subscripts and stand for the oxidized and reduced species respectively;
* is the concentration of the and species in the bulk;
* is the concentration of the electrolyte;
* denotes the surface area;
* denotes the fraction of the and species present.
The equation for applies to both reversible and quasi-reversible reactions for which both halves of the couple are soluble. | 0 | Theoretical and Fundamental Chemistry |
Conjugated systems form the basis of chromophores, which are light-absorbing parts of a molecule that can cause a compound to be colored. Such chromophores are often present in various organic compounds and sometimes present in polymers that are colored or glow in the dark. Chromophores often consist of a series of conjugated bonds and/or ring systems, commonly aromatic, which can include C–C, C=C, C=O, or N=N bonds.
Conjugated chromophores are found in many organic compounds including azo dyes (also artificial food additives), compounds in fruits and vegetables (lycopene and anthocyanidins), photoreceptors of the eye, and some pharmaceutical compounds such as the following:
Conjugated polymer nanoparticles (PDots) are assembled from hydrophobic fluorescent conjugated polymers, along with amphiphilic polymers to provide water solubility. Pdots are important labels for single-molecule fluorescence microscopy, based on high brightness, lack of blinking or dark fraction, and slow photobleaching. | 0 | Theoretical and Fundamental Chemistry |
In the BGIT, we assumed that a CH always makes a constant contribution to ΔH° values for cyclic system. H° values for a number of structures and represents an average value that gives the best agreement with the range of experimental data. In contrast, the strain energy of cyclobutane is specific to the parent compound, with their new corrections, it is now possible to predict ΔH° values for strained ring system by first adding up all the basic group increments and then adding appropriate ring-strain correction values.
The same as ring system, corrections have been made to other situations such as gauche alkane with a 0.8 kcal/mol correction and cis- alkene with a 1.0 kcal/mol correction.
Also, the BGIT fails when conjugation and interactions between functional groups exist, such as intermolecular and intramolecular hydrogen bonding, which limits its accuracy and usage in some cases. | 0 | Theoretical and Fundamental Chemistry |
Soderholm's more recent projects use machine learning to understand the influence of complex molecular structuring in solutions, in connection with low-energy processes for separation of f-block elements from complex mixtures. | 0 | Theoretical and Fundamental Chemistry |
Zeolitic imidazolate frameworks (ZIFs) are metal-organic frameworks similar to zeolites. Because of their porosity, chemical stability and thermal resistance, ZIFs are being examined for their capacity to capture carbon dioxide. | 0 | Theoretical and Fundamental Chemistry |
In physical chemistry, the Arrhenius equation is a formula for the temperature dependence of reaction rates. The equation was proposed by Svante Arrhenius in 1889, based on the work of Dutch chemist Jacobus Henricus van t Hoff who had noted in 1884 that the van t Hoff equation for the temperature dependence of equilibrium constants suggests such a formula for the rates of both forward and reverse reactions. This equation has a vast and important application in determining the rate of chemical reactions and for calculation of energy of activation. Arrhenius provided a physical justification and interpretation for the formula. Currently, it is best seen as an empirical relationship. It can be used to model the temperature variation of diffusion coefficients, population of crystal vacancies, creep rates, and many other thermally induced processes and reactions. The Eyring equation, developed in 1935, also expresses the relationship between rate and energy. | 0 | Theoretical and Fundamental Chemistry |
The above techniques can be combined with computational methods to estimate staining levels without staining the cell. These approaches, generally, rely on training a deep-convolutional neural network to perform imaging remapping, converting the bright-field or phase image into a fluorescent image. By decoupling the training corpus from the cells under investigation, these approaches provide an avenue for using stains that are otherwise incompatible with live cell imaging, such as anti-body staining. | 1 | Applied and Interdisciplinary Chemistry |
Certain materials, such as glass and glycerol, may harden without crystallizing; these are called amorphous solids. Amorphous materials, as well as some polymers, do not have a freezing point, as there is no abrupt phase change at any specific temperature. Instead, there is a gradual change in their viscoelastic properties over a range of temperatures. Such materials are characterized by a glass transition that occurs at a glass transition temperature, which may be roughly defined as the "knee" point of the material's density vs. temperature graph. Because vitrification is a non-equilibrium process, it does not qualify as freezing, which requires an equilibrium between the crystalline and liquid state. | 1 | Applied and Interdisciplinary Chemistry |
In dimensional analysis, a ratio which converts one unit of measure into another without changing the quantity is called a conversion factor. For example, kPa and bar are both units of pressure, and . The rules of algebra allow both sides of an equation to be divided by the same expression, so this is equivalent to . Since any quantity can be multiplied by 1 without changing it, the expression "" can be used to convert from bars to kPa by multiplying it with the quantity to be converted, including the unit. For example, because , and bar/bar cancels out, so . | 1 | Applied and Interdisciplinary Chemistry |
The earliest reports of tip enhanced Raman spectroscopy typically used a Raman microscope coupled with an atomic force microscope. Tip-enhanced Raman spectroscopy coupled with a scanning tunneling microscope (STM-TERS) has also become a reliable technique, since it utilizes the gap mode plasmon between the metallic probe and the metallic substrate. | 0 | Theoretical and Fundamental Chemistry |
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