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Myo-inositol trispyrophosphate (ITPP), also known as OXY111A, is an inositol phosphate that causes a rightward shift in the oxygen hemoglobin dissociation curve through allosteric modulation of hemoglobin within red blood cells. It is an experimental drug intended to reduce tissue hypoxia. The effects appear to last roughly as long as the affected red blood cells remain in circulation. | 1 | Applied and Interdisciplinary Chemistry |
Ethnochemistry is the study of chemical ideas found in any culture; where an appreciation of cultural heritage is preserved. In the West African country of Ghana, an example of this are the bead makers who do not explain what they're doing in modern chemical terms, though they do explain the process in their own artistic way. A similar concept is ethnomathematics; Achor, et al. concluded that there was a positive impact on the achievement of students and retention of knowledge when ethnomathematics is applied to a classroom setting, it can also help to make students aware of the role in which chemistry plays in their everyday lives. This suggests that similar results are possible in a chemistry classroom if ethnochemistry is applied. | 1 | Applied and Interdisciplinary Chemistry |
Disphenoidal or seesaw (also known as sawhorse) is a type of molecular geometry where there are four bonds to a central atom with overall C molecular symmetry. The name "seesaw" comes from the observation that it looks like a playground seesaw. Most commonly, four bonds to a central atom result in tetrahedral or, less commonly, square planar geometry.
The seesaw geometry occurs when a molecule has a steric number of 5, with the central atom being bonded to 4 other atoms and 1 lone pair (AXE in AXE notation). An atom bonded to 5 other atoms (and no lone pairs) forms a trigonal bipyramid with two axial and three equatorial positions, but in the seesaw geometry one of the atoms is replaced by a lone pair of electrons, which is always in an equatorial position. This is true because the lone pair occupies more space near the central atom (A) than does a bonding pair of electrons. An equatorial lone pair is repelled by only two bonding pairs at 90°, whereas a hypothetical axial lone pair would be repelled by three bonding pairs at 90° which would make it stable. Repulsion by bonding pairs at 120° is much smaller and less important. | 0 | Theoretical and Fundamental Chemistry |
4-Hydroxyphenylpyruvic acid (4-HPPA) is an intermediate in the metabolism of the amino acid phenylalanine. The aromatic side chain of phenylalanine is hydroxylated by the enzyme phenylalanine hydroxylase to form tyrosine. The conversion from tyrosine to 4-HPPA is in turn catalyzed by tyrosine aminotransferase. Additionally, 4-HPPA can be converted to homogentisic acid which is one of the precursors to ochronotic pigment.
It is an intermediary compound in the biosynthesis of scytonemin. | 1 | Applied and Interdisciplinary Chemistry |
The Venus Express orbiter collected Venus science data from April 2006 until December 2014. In 2008, Piccioni, et al. reported measurements of night-side airglow emission in the atmosphere of Venus made with the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express. They attributed emission bands in wavelength ranges of 1.40 - 1.49 micrometers and 2.6 - 3.14 micrometers to vibrational transitions of OH. This was the first evidence for OH in the atmosphere of any planet other than Earth's. | 0 | Theoretical and Fundamental Chemistry |
TRPS was developed by Izon Science Limited, producer of commercially available nanopore-based particle characterization systems. Izon Science Limited currently sell one TRPS device, known as the "Exoid". Previous devices include the "qNano", the "qNano Gold" and the "qViron". These systems have been applied to measure a wide range of biological and synthetic particle types including viruses and nanoparticles. TRPS has been applied in both academic and industrial research fields, including:
*Drug delivery research (e.g. lipid nanoparticles and liposomes)
*Extracellular vesicles such as exosomes
*Virology and vaccine production
*Biomedical diagnostics
*Microfluidics | 0 | Theoretical and Fundamental Chemistry |
While LCP was the first and sole method used to produce poly(phthalaldehyde), its usage nowadays has dramatically decreased in favor of other polymerization techniques which allow a better control over the polymer properties including molar mass and thermal stability. | 0 | Theoretical and Fundamental Chemistry |
Deprotonation of sulfonium and oxosulfonium salts affords ylides, of structure RS−C−R′ and RS(O)−C−R′. While sulfonium ylides, for instance in the Johnson–Corey–Chaykovsky reaction used to synthesize epoxides, are sometimes drawn with a C=S double bond, e.g., RS=CR′, the ylidic carbon–sulfur bond is highly polarized and is better described as being ionic. Sulfonium ylides are key intermediates in the synthetically useful Stevens rearrangement. Thiocarbonyl ylides (RR′C=S−C−RR′) can form by ring-opening of thiiranes, photocyclization of aryl vinyl sulfides, as well as by other processes. | 0 | Theoretical and Fundamental Chemistry |
For logic gates with a single input, there are four possible output patterns. When the input is 0, the output can be either a 0 or 1. When the input is 1, the output can again be 0 or 1. The four output bit patterns that can arise corresponds to a specific logic type: PASS 0, YES, NOT, and PASS 1. PASS 0 always outputs 0, whatever the input. PASS 1 always outputs 1, whatever the input. YES outputs a 1 when the input is 1, and NOT is the inverse of YES – it outputs a 0 when the input is 1.
AND, OR, XOR, NAND, NOR, XNOR, and INH are two-input logic gates. The AND, OR, and XOR gates are fundamental logic gates, and the NAND, NOR, and XNOR gates are complementary to AND, OR, and XOR gates, respectively. An INHIBIT (INH) gate is a special conditional logic gate that includes a prohibitory input. When the prohibitory input is absent, the output produced depends solely on the other input. | 0 | Theoretical and Fundamental Chemistry |
Capsinoids are alkaloid substances naturally present in chili peppers. Although they are structurally similar to capsaicin, the substance that causes pungency in hot peppers, they largely lack that characteristic. Capsinoids have an estimated "hot taste threshold" which is about 1/1000 that of capsaicin. Capsinoids were not reported in the scientific literature until 1989, when biologists first isolated them in a unique variety of chili peppers, CH-19 Sweet, which does not contain capsaicin. Capsinoids include capsiate, dihydrocapsiate, and nordihydrocapsiate.
Many health effects have been ascribed to capsaicin and capsinoids, both anecdotally and through scientific study, including anticancer, anti-inflammatory, and analgesic activities, and weight management. | 1 | Applied and Interdisciplinary Chemistry |
A purpose for introducing spiciness is to decrease the amount of state variables needed; the density at constant depth is a function of potential temperature and salinity and of using both, spiciness can be used. If the goal is to only quantify the variation of water parcels along isopycnals, the variation in absolute salinity or temperature can be used instead because it gives the same information with the same amount of variables.
Another purpose is to examine how the stability ratio varies vertically on a water column. The stability ratio is a number determining the involvement of temperature changes relative to the involvement salinity changes in a vertical profile, which yields relevant information about the stability of the water column:
The vertical variation of this number is often shown in a spiciness-potential density diagram and/or plot, where the angle shows the stability. | 0 | Theoretical and Fundamental Chemistry |
Home pill testing equipment is illegal in the US state of Illinois where the (720 ILCS 600/) Drug Paraphernalia Control Act specifically outlaws "testing equipment intended to be used unlawfully in a private home for identifying or in analyzing the strength, effectiveness or purity of cannabis or controlled substances;" | 0 | Theoretical and Fundamental Chemistry |
Various factors enhance the likelihood of MPTP opening. In some mitochondria, such as those in the central nervous system, high levels of Ca within mitochondria can cause the MPT pore to open. This is possibly because Ca binds to and activates Ca binding sites on the matrix side of the MPTP.
MPT induction is also due to the dissipation of the difference in voltage across the inner mitochondrial membrane (known as transmembrane potential, or Δψ).
In neurons and astrocytes, the contribution of membrane potential to MPT induction is complex, see.
The presence of free radicals, another result of excessive intracellular calcium concentrations, can also cause the MPT pore to open.
Other factors that increase the likelihood that the MPTP will be induced include the presence of certain fatty acids, and inorganic phosphate. However, these factors cannot open the pore without Ca, though at high enough concentrations, Ca alone can induce MPT.
Stress in the endoplasmic reticulum can be a factor in triggering MPT.
Conditions that cause the pore to close or remain closed include acidic conditions, high concentrations of ADP, high concentrations of ATP, and high concentrations of NADH. Divalent cations like Mg also inhibit MPT, because they can compete with Ca for the Ca binding sites on the matrix and/or cytoplasmic side of the MPTP. | 1 | Applied and Interdisciplinary Chemistry |
A program package MatchMiner was used to scan HUGO names for cloned genes of interest are scanned, then are input into GoMiner, which leveraged the GO to identify the biological processes, functions and components represented in the gene profile. Also, Database for Annotation, Visualization, and Integrated Discovery (DAVID) and KEGG database can be used for the analysis of microarray expression data and the analysis of each GO biological process (P), cellular component (C), and molecular function (F) ontology. In addition, DAVID tools can be used to analyze the roles of genes in metabolic pathways and show the biological relationships between genes or gene-products and may represent metabolic pathways. These two databases also provide bioinformatics tools online to combine specific biochemical information on a certain organism and facilitate the interpretation of biological meanings for experimental data. By using a combined approach of Microarray-Bioinformatic technologies, a potential metabolic mechanism contributing to colorectal cancer (CRC) has been demonstrated Several environmental factors may be involved in a series of points along the genetic pathway to CRC. These include genes associated with bile acid metabolism, glycolysis metabolism and fatty acid metabolism pathways, supporting a hypothesis that some metabolic alternations observed in colon carcinoma may occur in the development of CRC. | 0 | Theoretical and Fundamental Chemistry |
When ortho substitution occurs in benzoic acid, steric hindrance causes the carboxyl group to twist out of the plane of the benzene ring. The twisting inhibits the resonance of the carboxyl group with the phenyl ring, leading to increased acidity of the carboxyl group. This increased acidity contrasts with the reduced acidity caused by destabilizing cross-conjugation. The destabilizing cross-conjugation causes decreased acidity of benzoic acid compared to formic acid. | 0 | Theoretical and Fundamental Chemistry |
Sinking oceanic particles encompass a wide range of shape, porosity, ballast and other characteristics. The model shown in the diagram at the right attempts to capture some of the predominant features that influence the shape of the sinking flux profile (red line).
The sinking of organic particles produced in the upper sunlit layers of the ocean forms an important limb of the oceanic biological pump, which impacts the sequestration of carbon and resupply of nutrients in the mesopelagic ocean. Particles raining out from the upper ocean undergo remineralization by bacteria colonized on their surface and interior, leading to an attenuation in the sinking flux of organic matter with depth. The diagram illustrates a mechanistic model for the depth-dependent, sinking, particulate mass flux constituted by a range of sinking, remineralizing particles.
Marine snow varies in shape, size and character, ranging from individual cells to pellets and aggregates, most of which is rapidly colonized and consumed by heterotrophic bacteria, contributing to the attenuation of the sinking flux with depth. | 0 | Theoretical and Fundamental Chemistry |
A comparative NAIL-MS experiment is quite similar to a SILAC experiment but for RNA instead of proteins. First, two populations of the respective cells are cultivated. One of the cell populations is fed with growth medium containing unlabeled nutrients, whereas the second population is fed with growth medium containing stable isotope labeled nutrients. The cells then incorporate the respective isotopologues into their RNA molecules. One of the cell populations serves as a control group whereas the other is subject to the associated research (e.g. KO strain, stress). Upon harvesting of the two cell populations they are mixed and co-processed together to exclude purification-bias. Due to the distinct masses of incorporated nutrients into the nucleosides a differentiation of the two cell populations is possible by mass spectrometry. | 0 | Theoretical and Fundamental Chemistry |
The Brønsted catalysis equation or law of correlation, after Johannes Nicolaus Brønsted, gives the relationship between acid strength and catalytic activity in general acid catalysis.
A plot of the common logarithm of the reaction rate constant k versus the logarithm of the ionization constant K for a series of acids (for example a group of substituted phenols or carboxylic acids) gives a straight line with slope α and intercept C. The Brønsted equation is a free-energy relationship. The relationship implies that the Gibbs free energy for proton dissociation is proportional to the activation energy for the catalytic step. When the relationship is not linear, the chosen group of catalysts do not operate through the same reaction mechanism.
Specific and general catalysis is also found in base catalysed reactions and base Brønsted equation also exists with constant β.
The Brønsted equation gives information about a reaction mechanism. Reactions that have low values for proportionality constants α or β are considered to have a transition state closely resembling the reactant with little proton transfer. With a high value, proton transfer in the transition state is almost complete. In a study of a group of phenalene compounds it was concluded from Brønsted analysis that phenalene acidity is very different from either indene acidity or phenylene acidity. | 0 | Theoretical and Fundamental Chemistry |
Muon-catalyzed fusion is a fusion process that occurs at ordinary temperatures. It was studied in detail by Steven Jones in the early 1980s. Net energy production from this reaction has been unsuccessful because of the high energy required to create muons, their short 2.2 µs half-life, and the high chance that a muon will bind to the new alpha particle and thus stop catalyzing fusion. | 0 | Theoretical and Fundamental Chemistry |
There is an extension to DLTS known as a high resolution Laplace transform DLTS (LDLTS). Laplace DLTS is an isothermal technique in which the capacitance transients are digitized and averaged at a fixed temperature. Then the defect emission rates are obtained with a use of numerical methods being equivalent to the inverse Laplace transformation. The obtained emission rates are presented as a spectral plot. The main advantage of Laplace DLTS in comparison to conventional DLTS is the substantial increase in energy resolution understood here as an ability to distinguish very similar signals.
Laplace DLTS in combination with uniaxial stress results in a splitting of the defect energy level. Assuming a random distribution of defects in non-equivalent orientations, the number of split lines and their intensity ratios reflect the symmetry class of the given
defect.
Application of LDLTS to MOS capacitors needs device polarization voltages in a range where the Fermi level extrapolated from semiconductor to the semiconductor-oxide interface intersects this interface within the semiconductor bandgap range. The electronic interface states present at this interface can trap carriers similarly to defects described above. If their occupancy with electrons or holes is disturbed by a small voltage pulse then the device capacitance recovers after the pulse to its initial value as the interface states start to emit carriers. This recovery process can be analyzed with the LDLTS method for different device polarization voltages. Such a procedure allows to obtain the energy state distribution of the interface electronic states at the semiconductor-oxide (or dielectric) interfaces. | 0 | Theoretical and Fundamental Chemistry |
The Gran plot is based on the Nernst equation which can be written as
where E is a measured electrode potential, E is a standard electrode potential, s is the slope, ideally equal to RT/nF, and {H} is the activity of the hydrogen ion. The expression rearranges to
depending on whether the electrode is calibrated in millivolts or pH. For convenience the concentration, [H], is used in place of activity. In a titration of strong acid with strong alkali, the analytical concentration of the hydrogen ion is obtained from the initial concentration of acid, C and the amount of alkali added during titration.
where v is the initial volume of solution, c is the concentration of alkali in the burette and v is the titre volume. Equating the two expressions for [H] and simplifying, the following expression is obtained
A plot of against v will be a straight line. If E and s are known from electrode calibration, where the line crosses the x-axis indicates the volume at the equivalence point, . Alternatively, this plot can be used for electrode calibration by finding the values of E and s that give the best straight line. | 0 | Theoretical and Fundamental Chemistry |
The first time scientists were able to grow artificial hair follicles from stem cells was in 2010. Scientists at the Berlin Technical University in Germany took animal cells and created follicles by using them. As a result, they produced follicles "thinner than normal", but they were confident they could develop the right method of cloning hair from human stem cells by 2011. They estimated that the therapy would be publicly available by 2015 as they were already preparing for the clinical trials. Scientists working on the project said if the treatment was finished, it would mean a cure for approximately 80 percent of those who suffer from hair loss.
The university was working together with Intercytex and several other research teams, but they encountered several problems. One of them was that the multiplication process was not efficient enough. They were only able to clone one or two follicles from an extracted hair but for the process to be efficient this number should have been around 1000. There was no indication that researchers were able to overcome this obstacle. | 1 | Applied and Interdisciplinary Chemistry |
The early Iron Age in China began before 1000 BCE, with the introduction of ironware, such as knives, swords, and arrowheads, from the west into Xinjiang, before it further diffused to Qinghai and Gansu. In 2008, two iron fragments were excavated at the Mogou site, in Gansu. They have been dated to the 14th century BCE, belonging to the period of Siwa culture. One of the fragments was made of bloomery iron rather than meteoritic iron. | 1 | Applied and Interdisciplinary Chemistry |
The synthesis of molograms on the sensor chip is realized with properly designed surface chemistry and reactive immersion lithography (RIL). Through the RIL process the biomolecular recognition structure of the mologram on a light-sensitive non-fouling graft copolymer layer can be created by standard lithography techniques. The copolymer layer is functionalized with photocleavable protection groups that upon illumination create reactive amines. Subsequent surface chemistry steps enable an easy tailoring of recognition molecules specific to the desired analytical application. | 1 | Applied and Interdisciplinary Chemistry |
Climate change contributes to warmer waters which makes conditions more favorable for algae growth in more regions and farther north. In general, still, warm, shallow water, combined with high-nutrient conditions in lakes or rivers, increases the risk of harmful algal blooms. Warming of summer surface temperatures of lakes, which rose by 0.34 °C decade per decade between 1985 and 2009 due to global warming, also will likely increase algal blooming by 20% over the next century.
Although the drivers of harmful algal blooms are poorly understood, they do appear to have increased in range expansion and frequency in coastal areas since the 1980s. The is the result of human induced factors such as increased nutrient inputs (nutrient pollution) and climate change (in particular the warming of water temperatures). The parameters that affect the formation of HABs are ocean warming, marine heatwaves, oxygen loss, eutrophication and water pollution. | 0 | Theoretical and Fundamental Chemistry |
The addition of a benzene spacer in x-nucleobases affects the bases' optical absorption spectra. Time-dependent density functional theory (TDDFT) applied to xDNA revealed that the benzene component of the highest occupied molecular orbitals (HOMO) in the x-bases pins the absorption onset at an earlier point than natural bases. Another unusual feature of xDNA absorption spectra is the red-shifted excimers of xA in the low range. In terms of stacking fingerprints, there is a more pronounced hypochromicity seen in consecutive xA-T base pairs.
Implications of xDNA's altered absorption include applications in nanoelectronic technology and nanobiotechnology. The reduced spacing between x-nucleotides makes the helix stiffer, thus it is not as easily affected by substrate, electrode, and functional nanoparticle forces. Other alterations to natural nucleotides resulting in different absorption spectra will broaden these applications in the future. | 1 | Applied and Interdisciplinary Chemistry |
Trimethylsilyl azide , and tributyltin azide , have all been used, including enantioselective modifications of the reaction are also known. Aminoazides are accessible by the epoxide and aziridine ring cleavage, respectively. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, trigonal planar is a molecular geometry model with one atom at the center and three atoms at the corners of an equilateral triangle, called peripheral atoms, all in one plane. In an ideal trigonal planar species, all three ligands are identical and all bond angles are 120°. Such species belong to the point group D. Molecules where the three ligands are not identical, such as HCO, deviate from this idealized geometry. Examples of molecules with trigonal planar geometry include boron trifluoride (BF), formaldehyde (HCO), phosgene (COCl), and sulfur trioxide (SO). Some ions with trigonal planar geometry include nitrate (), carbonate (), and guanidinium (). In organic chemistry, planar, three-connected carbon centers that are trigonal planar are often described as having sp hybridization.
Nitrogen inversion is the distortion of pyramidal amines through a transition state that is trigonal planar.
Pyramidalization is a distortion of this molecular shape towards a tetrahedral molecular geometry. One way to observe this distortion is in pyramidal alkenes. | 0 | Theoretical and Fundamental Chemistry |
With hexagonal and rhombohedral lattice systems, it is possible to use the Bravais–Miller system, which uses four indices (h k i ℓ) that obey the constraint
: h + k + i = 0.
Here h, k and ℓ are identical to the corresponding Miller indices, and i is a redundant index.
This four-index scheme for labeling planes in a hexagonal lattice makes permutation symmetries apparent. For example, the similarity between (110) ≡ (110) and (10) ≡ (110) is more obvious when the redundant index is shown.
In the figure at right, the (001) plane has a 3-fold symmetry: it remains unchanged by a rotation of 1/3 (2/3 rad, 120°). The [100], [010] and the [0] directions are really similar. If S is the intercept of the plane with the [0] axis, then
: i = 1/S.
There are also ad hoc schemes (e.g. in the transmission electron microscopy literature) for indexing hexagonal lattice vectors (rather than reciprocal lattice vectors or planes) with four indices. However they don't operate by similarly adding a redundant index to the regular three-index set.
For example, the reciprocal lattice vector (hkℓ) as suggested above can be written in terms of reciprocal lattice vectors as . For hexagonal crystals this may be expressed in terms of direct-lattice basis-vectors a, a and a as
Hence zone indices of the direction perpendicular to plane (hkℓ) are, in suitably normalized triplet form, simply . When four indices are used for the zone normal to plane (hkℓ), however, the literature often uses instead. Thus as you can see, four-index zone indices in square or angle brackets sometimes mix a single direct-lattice index on the right with reciprocal-lattice indices (normally in round or curly brackets) on the left.
And, note that for hexagonal interplanar distances, they take the form | 0 | Theoretical and Fundamental Chemistry |
Because applying mathematical equations to turbulent flow and diffusion is so difficult, research in this area has been lacking until recently. In the past, laboratory efforts have used data from steady flow in streams or from fluids, that have a high Reynolds number, flowing through pipes, but it is difficult to obtain accurate data from these methods. This is because these methods involve ideal flow, which cannot simulate the conditions of turbulent flow necessary for developing turbulent diffusion models. With the advancement in computer-aided modeling and programming, scientists have been able to simulate turbulent flow in order to better understand turbulent diffusion in the atmosphere and in fluids.
Currently in use on research efforts are two main non-intrusive applications. The first is planar laser-induced fluorescence (PLIF), which is used to detect instantaneous concentrations at up to one million points per second. This technology can be paired with particle image velocimetry (PIV), which detects instantaneous velocity data. In addition to finding concentration and velocity data, these techniques can be used to deduce spatial correlations and changes in the environment. As technology and computer abilities are rapidly expanding, these methods will also improve greatly, and will more than likely be at the forefront of future research on modeling turbulent diffusion.
Aside from these efforts, there also have been advances in fieldwork used before computers were available. Real-time monitoring of turbulence, velocity and currents for fluid mixing is now possible. This research has proved important for studying the mixing cycles of contaminants in turbulent flows, especially for drinking water supplies.
As researching techniques and availability increase, many new areas are showing interest in utilizing these methods. Studying how robotics or computers can detect odor and contaminants in a turbulent flow is one area that will likely produce a lot of interest in research. These studies could help the advancement of recent research on placing sensors in aircraft cabins to effectively detect biological weapons and/or viruses. | 1 | Applied and Interdisciplinary Chemistry |
R-410A, sold under the trademarked names AZ-20, EcoFluor R410, Forane 410A, Genetron R410A, Puron, and Suva 410A, is a zeotropic but near-azeotropic mixture of difluoromethane (CHF, called R-32) and pentafluoroethane (CHFCF, called R-125) that is used as a refrigerant in air conditioning and heat pump applications. R-410A cylinders were colored rose but are no longer specially color-coded, now bearing a standard light gray color.
On December 27, 2020, the United States Congress passed the American Innovation and Manufacturing (AIM) Act, which directs US Environmental Protection Agency (EPA) to phase down production and consumption of hydrofluorocarbons (HFCs). HFCs have a high global warming potential and contribute to climate change. Rules developed under the AIM Act require HFC production and consumption to be reduced by 85% from 2022 to 2036. R-410A will be restricted by this Act because it contains the HFC R-125. Other refrigerants (like R-32 and R-454B) will replace R-410A in most applications, just as R-410A replaced the earlier refrigerant, R-22. | 1 | Applied and Interdisciplinary Chemistry |
For low shear rates, dilute suspensions or suspensions involving small particles, the viscosity of the fluid is a much stronger effect than the inertia of the particles. The particles do not interact strongly with each other. By considering the forces on a particle in a fluid in the Stokes regime, it can be shown that the presence of the particle simply increases the effective viscosity of the fluid.
At high shear rates, the inertia of the particles is the dominant effect, and the suspension's behaviour is governed by collisions between particles. In his 1954 paper, Bagnold justified the quadratic relationship by collisional arguments. He considered an idealised situation in which layers of particles are regular, and slide and collide regularly with each other. Then the impulse of each collision between particles is proportional to the shear rate, and so is the number of collisions per unit time; and hence the total impulse on a particle per unit time is proportional to the square of the shear rate. | 1 | Applied and Interdisciplinary Chemistry |
Agricultural chemistry is the chemistry, especially organic chemistry and biochemistry, as they relate to agriculture. Agricultural chemistry embraces the structures and chemical reactions relevant in the production, protection, and use of crops and livestock. Its applied science and technology aspects are directed towards increasing yields and improving quality, which comes with multiple advantages and disadvantages. | 1 | Applied and Interdisciplinary Chemistry |
Light-harvesting complex I is permanently bound to photosystem I via the plant-specific subunit PsaG. It is made up of four proteins: Lhca1, Lhca2, Lhca3, and Lhca4, all of which belong to the LHC or chlorophyll a/b-binding family. The LHC wraps around the PS1 reaction core. | 0 | Theoretical and Fundamental Chemistry |
The dimension of physical quantities of interest in mechanics can be expressed in terms of base dimensions T, L, and M – these form a 3-dimensional vector space. This is not the only valid choice of base dimensions, but it is the one most commonly used. For example, one might choose force, length and mass as the base dimensions (as some have done), with associated dimensions F, L, M; this corresponds to a different basis, and one may convert between these representations by a change of basis. The choice of the base set of dimensions is thus a convention, with the benefit of increased utility and familiarity. The choice of base dimensions is not entirely arbitrary, because they must form a basis: they must span the space, and be linearly independent.
For example, F, L, M form a set of fundamental dimensions because they form a basis that is equivalent to T, L, M: the former can be expressed as [F = LM/T], L, M, while the latter can be expressed as [T = (LM/F)], L, M.
On the other hand, length, velocity and time (T, L, V) do not form a set of base dimensions for mechanics, for two reasons:
* There is no way to obtain mass – or anything derived from it, such as force – without introducing another base dimension (thus, they do not span the space).
* Velocity, being expressible in terms of length and time (), is redundant (the set is not linearly independent). | 1 | Applied and Interdisciplinary Chemistry |
Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. Common heat treatment processes include annealing, precipitation hardening, quenching, and tempering:
* annealing softens the metal by allowing recovery of cold work and grain growth.
* quenching can be used to harden alloy steels, or in precipitation hardenable alloys, to trap dissolved solute atoms in solution.
* tempering will cause the dissolved alloying elements to precipitate, or in the case of quenched steels, improve impact strength and ductile properties.
Often, mechanical and thermal treatments are combined in what is known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high alloy special steels, super alloys and titanium alloys. | 1 | Applied and Interdisciplinary Chemistry |
Nitric acid is a source of nitric oxide complexes, although the details are obscure. Probably relevant is the conventional self-dehydration of nitric acid:
: 2 HNO → NONO + HO
Nitric acid is used in some preparations of nitroprusside from ferrocyanide:
: HNO + [Fe(CN)] → [Fe(CN)(NO)] + OH + OCN | 0 | Theoretical and Fundamental Chemistry |
In May 2015, the New England Journal of Medicine emphasized the importance of pharmaceutical industry-physician interactions for the development of novel treatments, and argued that moral outrage over industry malfeasance had unjustifiably led many to overemphasize the problems created by financial conflicts of interest. The article noted that major healthcare organizations, such as National Center for Advancing Translational Sciences of the National Institutes of Health, the President's Council of Advisors on Science and Technology, the World Economic Forum, the Gates Foundation, the Wellcome Trust, and the Food and Drug Administration had encouraged greater interactions between physicians and industry in order to improve benefits to patients. | 1 | Applied and Interdisciplinary Chemistry |
The closure of tidal inlets serves various primary purposes:
* Land reclamation
* Shortening sea defence length
* Creation of fresh water reservoirs
* Establishment of tidal energy basins
* Development of fixed-level harbour docks
* Construction of docks for marine activities
* Provision of road or rail connections
* Repair of breaches in dikes
* Creation of fish ponds.
Historically, the closure of inlets was primarily aimed at land reclamation and water level control in marshy areas, facilitating agricultural development. Such activities necessitated effective management of river and storm surge levels, often requiring ongoing dike maintenance. Secondary purposes, such as tidal energy generation, harbour and construction docks, dams for transportation infrastructure, and fish farming, also emerged but had lesser environmental impact.
In contemporary times, driven by a growing emphasis on quality of life, particularly in industrialised nations, inlet closure projects encompass a broader spectrum of objectives. These may include creating freshwater storage facilities, mitigating water pollution in designated zones, providing recreational amenities, and combating saltwater intrusion or groundwater contamination. | 1 | Applied and Interdisciplinary Chemistry |
Three forms of the sixth-order Kuramoto–Sivashinsky equations are encountered in applications involving tricritical points, which are given by | 1 | Applied and Interdisciplinary Chemistry |
Protein adsorption and protein fouling can cause major problems in the food industry (particularly the dairy industry) when proteins from food adsorb to processing surfaces, such as stainless steel or plastic (e.g. polypropylene). Protein fouling is the gathering of protein aggregates on a surface. This is most common in heating processes that create a temperature gradient between the equipment and the bulk substance being heated. In protein-fouled heating equipment, adsorbed proteins can create an insulating layer between the heater and the bulk material, reducing heating efficiency. This leads to inefficient sterilization and pasteurization. Also, proteins stuck to the heater may cause a burned taste or color in the bulk material. Additionally, in processes that employ filtration, protein aggregates that gather on the surface of the filter can block the flow of the bulk material and greatly reduce filter efficiency. | 1 | Applied and Interdisciplinary Chemistry |
The THz fields can be applied to accelerate electrons out of their equilibrium. If this is done fast enough, one can measure the elementary processes, such as how fast the screening of the Coulomb interaction is built up. This was experimentally explored in Ref. where it was shown that screening is complete within tens of femtoseconds in semiconductors. These insights are very important to understand how electronic plasma behaves in solids.
The Coulomb interaction can also pair electrons and holes into excitons, as discussed above. Due to their analog to the hydrogen atom, excitons have bound states that can be uniquely identified by the usual quantum numbers 1s, 2s, 2p, and so on. In particular, 1s-to-2p transition is dipole allowed and can be directly generated by E(t) if the photon energy matches the transition energy. In gallium arsenide-type systems, this transition energy is roughly 4 meV that corresponds to 1 THz photons. At resonance, the dipole d defines the Rabi energy Ω = d E(t) that determines the time scale at which the 1s-to-2p transition proceeds.
For example, one can excite the excitonic transition with an additional optical pulse which is synchronized with the THz pulse. This technique is called transient THz spectroscopy. Using this technique one can follow the formation dynamics of excitons or observe THz gain arising from intraexcitonic transitions.
Since a THz pulse can be intense and short, e.g., single-cycle, it is experimentally possible to realize situations where duration of the pulse, time scale related to Rabi- as well as the THz photon energy ħω are degenerate. In this situation, one enters the realm of extreme nonlinear optics where the usual approximations, such as the rotating-wave approximation (abbreviated as RWA) or the conditions for complete state transfer, break down. As a result, the Rabi oscillations become strongly distorted by the non-RWA contributions, the multiphoton absorption or emission processes, and the dynamic Franz–Keldysh effect, as measured in Refs.
By using a free-electron laser, one can generate longer THz pulses that are more suitable for detecting the Rabi oscillations directly. This technique could indeed demonstrate the Rabi oscillations, or actually the related Autler–Townes splitting, in experiments. The Rabi splitting has also been measured with a short THz pulse and also the onset to multi-THz-photon ionization has been detected, as the THz fields are made stronger. Recently, it has also been shown that the Coulomb interaction causes nominally dipole-forbidden intra-excitonic transitions to become partially allowed. | 0 | Theoretical and Fundamental Chemistry |
The majority of quorum sensing systems that fall under the "two-gene" (an autoinducer synthase coupled with a receptor molecule) paradigm as defined by the Vibrio fischeri system occur in the gram-negative Pseudomonadota. A comparison between the Pseudomonadota phylogeny as generated by 16S ribosomal RNA sequences and phylogenies of LuxI-, LuxR-, or LuxS-homologs shows a notably high level of global similarity. Overall, the quorum sensing genes seem to have diverged along with the Pseudomonadota phylum as a whole. This indicates that these quorum sensing systems are quite ancient, and arose very early in the Pseudomonadota lineage.
Although examples of horizontal gene transfer are apparent in LuxI, LuxR, and LuxS phylogenies, they are relatively rare. This result is in line with the observation that quorum sensing genes tend to control the expression of a wide array of genes scattered throughout the bacterial chromosome. A recent acquisition by horizontal gene transfer would be unlikely to have integrated itself to this degree. Given that the majority of autoinducer–synthase/receptor pairs occur in tandem in bacterial genomes, it is also rare that they switch partners and so pairs tend to co-evolve.
In quorum sensing genes of Gammaproteobacteria, which includes Pseudomonas aeruginosa and Escherichia coli, the LuxI/LuxR genes form a functional pair, with LuxI as the auto-inducer synthase and LuxR as the receptor. Gammaproteobacteria are unique in possessing quorum sensing genes, which, although functionally similar to the LuxI/LuxR genes, have a markedly divergent sequence. This family of quorum-sensing homologs may have arisen in the Gammaproteobacteria ancestor, although the cause of their extreme sequence divergence yet maintenance of functional similarity has yet to be explained. In addition, species that employ multiple discrete quorum sensing systems are almost all members of the Gammaproteobacteria, and evidence of horizontal transfer of quorum sensing genes is most evident in this class. | 1 | Applied and Interdisciplinary Chemistry |
4-Hydroxyestrone (4-OHE1), also known as estra-1,3,5(10)-triene-3,4-diol-17-one, is an endogenous, naturally occurring catechol estrogen and a minor metabolite of estrone and estradiol. It is estrogenic, similarly to many other hydroxylated estrogen metabolites such as 2-hydroxyestradiol, 16α-hydroxyestrone, estriol (16α-hydroxyestradiol), and 4-hydroxyestradiol but unlike 2-hydroxyestrone. | 1 | Applied and Interdisciplinary Chemistry |
Diffusivity, mass diffusivity or diffusion coefficient is usually written as the proportionality constant between the molar flux due to molecular diffusion and the negative value of the gradient in the concentration of the species. More accurately, the diffusion coefficient times the local concentration is the proportionality constant between the negative value of the mole fraction gradient and the molar flux. This distinction is especially significant in gaseous systems with strong temperature gradients. Diffusivity derives its definition from Fick's law and plays a role in numerous other equations of physical chemistry.
The diffusivity is generally prescribed for a given pair of species and pairwise for a multi-species system. The higher the diffusivity (of one substance with respect to another), the faster they diffuse into each other. Typically, a compound's diffusion coefficient is ~10,000× as great in air as in water. Carbon dioxide in air has a diffusion coefficient of 16 mm/s, and in water its diffusion coefficient is 0.0016 mm/s.
Diffusivity has dimensions of length / time, or m/s in SI units and cm/s in CGS units. | 1 | Applied and Interdisciplinary Chemistry |
*1.[https://web.archive.org/web/20060118094514/http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=5039 Nanotechnology: Molecular Speculations on Global Abundance]
*2.[https://www.amazon.com/gp/product/354067215X Functional MRI] | 1 | Applied and Interdisciplinary Chemistry |
Cyclopentadienyl derivatives of Ce are particularly well characterized. Hundreds have been examined by X-ray crystallography. The depicted is one of many.
Some of the best characterized organocerium(IV) compounds feature cyclopentadienyl ligands, e.g. | 0 | Theoretical and Fundamental Chemistry |
The compound's band structure exhibits a double Dirac cone, enabling Dirac fermions. A 30 meV gap separates the cones, which indicates the quantum Hall effect and massive Dirac fermions. Close measurement of the Fermi surface via the de Haas-van Alphen effect suggests that the massive fermions also exhibit Kane-Mele-type spin-orbit coupling.
FeSn can also host magnetic skyrmions, but these typically require high magnetic fields to nucleate. For samples with a small (but nonzero) thickness gradient, only a small-amplitude (5-10 mT), direction-variant magnetic field suffices to nucleate the quasiparticles. | 1 | Applied and Interdisciplinary Chemistry |
In rat models, the specific effect of MAM on neural development depends on the gestational age of the subject. At the seventeenth gestational day (GD17), administration of MAM produces behavioral and histopathological patterns found in schizophrenia. The molecular mechanism behind this model is not fully known. Methylazoxymethanol acetate administered at GD17 reduces the thickness of the hippocampus and the thalamus. The locomotor effects of amphetamines and the spontaneous firing rate of dopaminergic neurons in the ventral tegmental area are increased. In alternating maze tests, GD17 MAM rats quickly learned the first rule, but took longer to accommodate to alterations to the rule; this is thought to indicate deficits in working spatial memory, which is also impaired in schizophrenia. Another study found that mice whom methylazoxy-methanol acetate was administered on 16th gestational day, but not those whom it was administered on GD17 showed decreased parvalbumin expression in hippocampus and prefrontal cortex, and schizophrenia-like characteristics. Mice whom MAM was administered on GD16 also exhibited reduced size of hippocampus and thinning of the prefrontal cortex. PFC-dependent cognitive deficits were shown only in male MAM-treated mice. | 1 | Applied and Interdisciplinary Chemistry |
The recent identification of several antimicrobial compounds from the secretions of animal dermal scent glands may be the beginning of a promising new area of drug development. Assuming functional analogs of these lead compounds can be synthesized and found to be effective in vivo, the potential exists for producing new antimicrobial agents against pathogenic skin microorganisms. | 1 | Applied and Interdisciplinary Chemistry |
Half-sandwich compounds employing Ru(II), such as (cymene)ruthenium dichloride dimer, have been mainly investigated as catalysts for transfer hydrogenation. These complexes feature three coordination sites that are susceptible to substitution, while the arene ligand is tightly bonded and protects the metal against oxidation to Ru(III). They are prepared by reaction of RuCl·x(HO) with 1,3-cyclohexadienes. Work is also conducted on their potential as anticancer drugs.
(η-CH)RuCl readily undergoes ligand exchange via cleavage of the chloride bridges, making this complex a versatile precursor to Ru(II) piano stool derivatives. | 0 | Theoretical and Fundamental Chemistry |
The effect of the sigma electron displacement towards the more electronegative atom by which one end becomes positively charged and the other end negatively charged is known as the inductive effect. The -I effect is a permanent effect & generally represented by an arrow on the bond.
However, some groups, such as the alkyl group, are less electron-withdrawing than hydrogen and are therefore considered as electron-releasing/ electron-donating groups. This is electron-releasing character and is indicated by the +I effect. In short, alkyl groups tend to give electrons, leading to the induction effect. However, such an effect has been questioned.
As the induced change in polarity is less than the original polarity, the inductive effect rapidly dies out and is significant only over a short distance. Moreover, the inductive effect is permanent but feeble since it involves the shift of strongly held σ-bond electrons and other stronger factors may overshadow this effect. | 0 | Theoretical and Fundamental Chemistry |
In 1899, Charles Ernest Overton and Hans Horst Meyer independently proposed that the tadpole toxicity of non-ionizable organic compounds depends on their ability to partition into lipophilic compartments of cells. They further proposed the use of the partition coefficient in an olive oil/water mixture as an estimate of this lipophilic associated toxicity. Corwin Hansch later proposed the use of n-octanol as an inexpensive synthetic alcohol that could be obtained in a pure form as an alternative to olive oil. | 0 | Theoretical and Fundamental Chemistry |
Sucrose esters or sucrose fatty acid esters are a group of non-naturally occurring surfactants chemically synthesized from the esterification of sucrose and fatty acids (or glycerides). This group of substances is remarkable for the wide range of hydrophilic-lipophilic balance (HLB) that it covers. The polar sucrose moiety serves as a hydrophilic end of the molecule, while the long fatty acid chain serves as a lipophilic end of the molecule. Due to this amphipathic property, sucrose esters act as emulsifiers; i.e., they have the ability to bind both water and oil simultaneously. Depending on the HLB value, some can be used as water-in-oil emulsifiers, and some as oil-in-water emulsifiers. Sucrose esters are used in cosmetics, food preservatives, food additives, and other products. A class of sucrose esters with highly substituted hydroxyl groups, olestra, is also used as a fat replacer in food. | 0 | Theoretical and Fundamental Chemistry |
Corpuscularianism is similar to atomism, except that where atoms were supposed to be indivisible, corpuscles could in principle be divided. In this manner, for example, it was theorized that mercury could penetrate into metals and modify their inner structure, a step on the way towards transmutative production of gold. Corpuscularianism was associated by its leading proponents with the idea that some of the properties that objects appear to have are artifacts of the perceiving mind: secondary qualities as distinguished from primary qualities. Not all corpuscularianism made use of the primary-secondary quality distinction, however. An influential tradition in medieval and early modern alchemy argued that chemical analysis revealed the existence of robust corpuscles that retained their identity in chemical compounds (to use the modern term). William R. Newman has dubbed this approach to matter theory "chymical atomism," and has argued for its significance to both the mechanical philosophy and to the chemical atomism that emerged in the early 19th century.
Corpuscularianism stayed a dominant theory over the next several hundred years and retained its links with alchemy in the work of scientists such as Robert Boyle (1627–1692) and Isaac Newton in the 17th century. It was used by Newton, for instance, in his development of the corpuscular theory of light. The form that came to be accepted by most English scientists after Robert Boyle was an amalgam of the systems of Descartes and Gassendi. In The Sceptical Chymist (1661), Boyle demonstrates problems that arise from chemistry, and offers up atomism as a possible explanation. The unifying principle that would eventually lead to the acceptance of a hybrid corpuscular–atomism was mechanical philosophy, which became widely accepted by physical sciences. | 1 | Applied and Interdisciplinary Chemistry |
In some areas, where more land is available, sewage is treated in large round or oval ditches with one or more horizontal aerators typically called brush or disc aerators which drive the mixed liquor around the ditch and provide aeration. These are oxidation ditches, often referred to by manufacturer's trade names such as Pasveer, Orbal, or Carrousel. They have the advantage that they are relatively easy to maintain and are resilient to shock loads that often occur in smaller communities (i.e. at breakfast time and in the evening).
Oxidation ditches are installed commonly as fit & forget technology, with typical design parameters of a hydraulic retention time of 24 – 48 hours, and a sludge age of 12 – 20 days. This compares with nitrifying activated sludge plants having a retention time of 8 hours, and a sludge age of 8 – 12 days. | 1 | Applied and Interdisciplinary Chemistry |
Authorities in Italy are investigating a Ndrangheta mafia clan accused of trafficking and illegally dumping nuclear waste. According to a whistleblower, a manager of the Italys state energy research agency Enea paid the clan to get rid of 600 drums of toxic and radioactive waste from Italy, Switzerland, France, Germany, and the United States, with Somalia as the destination, where the waste was buried after buying off local politicians. Former employees of Enea are suspected of paying the criminals to take waste off their hands in the 1980s and 1990s. Shipments to Somalia continued into the 1990s, while the Ndrangheta clan also blew up shiploads of waste, including radioactive hospital waste, sending them to the sea bed off the Calabrian coast. According to the environmental group Legambiente, former members of the Ndrangheta have said that they were paid to sink ships with radioactive material for the last 20 years.
In 2008, Afghan authorities accused Pakistan of illegally dumping nuclear waste in the southern parts of Afghanistan when the Taliban were in power between 1996 and 2001. The Pakistani government denied the allegation. | 0 | Theoretical and Fundamental Chemistry |
Early transition metal amides may be prepared by treating anhydrous metal chloride with alkali amide reagents. In some cases, two equivalents of a secondary amine can be used, one equivalent serving as a base:
:MCl + n LiNR → M(NR) + n LiCl
:MCl + 2n HNR → M(NR) + n HNR·HCl
Transition metal amide complexes have been prepared by these methods:
* treating a halide complex with an alkali amide
* deprotonation of a coordinated amine
* oxidative addition of an amine | 0 | Theoretical and Fundamental Chemistry |
In situations where permanent magnetisation is not possible, e.g. above the Curie temperature, to maintain a magnetic field must be large enough such that induction outweighs diffusion.
It is not the absolute magnitude of velocity that is important for induction, but rather the relative differences and shearing in the flow, which stretch and fold magnetic field lines
. A more appropriate form for the magnetic Reynolds number in this case is therefore
where S is a measure of strain.
One of the most well known results is due to Backus
which states that the minimum for generation of a magnetic field by flow in a sphere is such that
where is the radius of the sphere and is the maximum strain rate.
This bound has since been improved by approximately 25% by Proctor.
Many studies of the generation of magnetic field by a flow consider the computationally-convenient periodic cube. In this case the minimum is found to be
where is the root-mean-square strain over a scaled domain with sides of length . If shearing over small length scales in the cube is ruled out, then is the minimum, where is the root-mean-square value. | 1 | Applied and Interdisciplinary Chemistry |
Lead azide is highly sensitive and usually handled and stored under water in insulated rubber containers. It will explode after a fall of around 150 mm (6 in) or in the presence of a static discharge of 7 millijoules. Its detonation velocity is around .
Ammonium acetate and sodium dichromate are used to destroy small quantities of lead azide.
Lead azide has immediate deflagration to detonation transition (DDT), meaning that even small amounts undergo full detonation (after being hit by flame or static electricity).
Lead azide reacts with copper, zinc, cadmium, or alloys containing these metals to form other azides. For example, copper azide is even more explosive and too sensitive to be used commercially.
Lead azide was a component of the six .22 (5.6 mm) caliber Devastator rounds fired from a Röhm RG-14 revolver by John Hinckley, Jr. in his assassination attempt on U.S. President Ronald Reagan on March 30, 1981. The rounds consisted of lead azide centers with lacquer-sealed aluminum tips designed to explode upon impact. A strong probability exists that the bullet which struck White House press secretary James Brady in the head exploded. The remaining bullets that hit people, including the shot that hit President Reagan, did not explode. | 0 | Theoretical and Fundamental Chemistry |
A grant from the Engineering and Physical Sciences Research Council of £25,249 was awarded on 19 January 2010 to extend the video library to include topical videos on molecules of general interest. The first of these new videos were on carbon dioxide and methane. | 1 | Applied and Interdisciplinary Chemistry |
In 2016 the first GaN CMOS logic using PMOS and NMOS transistors was reported with gate lengths of 0.5 μm (gate widths of the PMOS and NMOS transistors were 500 μm and 50 μm, respectively). | 0 | Theoretical and Fundamental Chemistry |
Because of limited computing power, specialized simulation models have been developed for various purposes depending on the time scale:
a) Electronic scale simulations (density function theory, ab-initio molecular dynamics): sub-atomic length scale in femto-second time scale
b) Atomic scale simulations (MD): nano to micro-meter length scale in nano-second time scale
c) Film scale simulation (KMC): micro-meter length scale in micro to hour time scale.
d) Reactor scale simulation (phase field model): meter length scale in year time scale.
Multiscale modeling techniques have also been developed to deal with overlapping time scales. | 0 | Theoretical and Fundamental Chemistry |
The activity of the daughter is given by the Bateman equation:
where and are the activity of the parent and daughter, respectively. and are the half-lives (inverses of reaction rates in the above equation modulo ln(2)) of the parent and daughter, respectively, and BR is the branching ratio.
In transient equilibrium, the Bateman equation cannot be simplified by assuming the daughters half-life is negligible compared to the parents half-life. The ratio of daughter-to-parent activity is given by: | 0 | Theoretical and Fundamental Chemistry |
ABS is an excellent method to employ for the extraction of proteins/enzymes and other labile biomolecules from crude cell extracts or other mixtures. Most often, this technique is employed in enzyme technology during industrial or laboratory production of enzymes.
* They provide mild conditions that do not harm or denature unstable/labile biomolecules
* The interfacial stress (at the interface between the two layers) is far lower (400-fold less) than water-organic solvent systems used for solvent extraction, causing less damage to the molecule to be extracted
* The polymer layer stabilizes the extracted protein molecules, favouring a higher concentration of the desired protein in one of the layers, resulting in an effective extraction
* Specialised systems may be developed (by varying factors such as temperature, degree of polymerisation, presence of certain ions etc. ) to favour the enrichment of a specific compound, or class of compounds, into one of the two phases. They are sometimes used simultaneously with ion-exchange resins for better extraction
* Separation of the phases and the partitioning of the compounds occurs rapidly. This allows the extraction of the desired molecule before endogenous proteases can degrade them.
* These systems are amenable to scale-ups, from laboratory-sized set-ups to those that can handle the requirements of industrial production. They may be employed in continuous protein-extraction processes.
Specificity may be further increased by tagging ligands specific to the desired enzyme, onto the polymer. This results in a preferential binding of the enzyme to the polymer, increasing the effectiveness of the extraction.
One major disadvantage, however, is the cost of materials involved, namely high-purity dextrans employed for the purpose. However, other low-cost alternatives such as less refined dextrans, hydroxypropyl starch derivatives and high-salt solutions are also available. | 0 | Theoretical and Fundamental Chemistry |
The mechanical properties of titanium foams are sensitive to the presence of interstitial solutes, which present limitations to processing routes and utilization. Titanium has a high affinity for atmospheric gases. In foams, this is evidenced by the metal's tendency to trap oxides within cell edges.
Micro-hardness of cell walls, elastic modulus, and yield strength increase as a result of interstitial solutes; ductility, which is a function of the quantity of interstitial impurities, is consequently reduced. Of the atmospheric gases, nitrogen has the most significant impact, followed by oxygen and carbon.
These impurities are often present in the precursor mixture and also introduced during processing. | 0 | Theoretical and Fundamental Chemistry |
Trimethyloxonium tetrafluoroborate can be used for esterification of carboxylic acids under conditions where acid-catalyzed reactions are infeasible:
Although rarely employed for esterifications, carboxylate salts (often generated in situ) react with electrophilic alkylating agents, such as alkyl halides, to give esters. Anion availability can inhibit this reaction, which correspondingly benefits from phase transfer catalysts or such highly polar aprotic solvents as DMF. An additional iodide salt may, via the Finkelstein reaction, catalyze the reaction of a recalcitrant alkyl halide. Alternatively, salts of a coordinating metal, such as silver, may improve the reaction rate by easing halide elimination. | 0 | Theoretical and Fundamental Chemistry |
Dissimilatory nitrate reduction to ammonium (DNRA), also known as nitrate/nitrite ammonification, is the result of anaerobic respiration by chemoorganoheterotrophic microbes using nitrate (NO) as an electron acceptor for respiration. In anaerobic conditions microbes which undertake DNRA oxidise organic matter and use nitrate (rather than oxygen) as an electron acceptor, reducing it to nitrite, and then to ammonium (NO → NO → NH).
Dissimilatory nitrate reduction to ammonium is more common in prokaryotes but may also occur in eukaryotic microorganisms. DNRA is a component of the terrestrial and oceanic nitrogen cycle. Unlike denitrification, it acts to conserve bioavailable nitrogen in the system, producing soluble ammonium rather than unreactive nitrogen gas (). | 1 | Applied and Interdisciplinary Chemistry |
Nitrosyl complexes are traditionally prepared by treating metal complexes with nitric oxide. The method is mainly used with reduced precursors. Illustrative is the nitrosylation of cobalt carbonyl to give cobalt tricarbonyl nitrosyl:
:Co(CO) + 2NO → 2CoNO(CO) + 2CO | 0 | Theoretical and Fundamental Chemistry |
Norgestrel (rac-13-ethyl-17α-ethynyl-19-nortestosterone), the racemic mixture containing levonorgestrel and dextronorgestrel, was discovered by Hughes and colleagues at Wyeth in 1963 via structural modification of norethisterone (17α-ethynyl-19-nortestosterone). It was the first progestogen to be manufactured via total chemical synthesis. Norgestrel was introduced for medical use as a combined birth control pill with ethinylestradiol under the brand name Eugynon in Germany in 1966 and under the brand name Ovral in the United States 1968, and as a progestogen-only pill under the brand name Ovrette in the United States in 1973. Following its discovery, norgestrel had been licensed by Wyeth to Schering AG, which separated the racemic mixture into its two optical isomers and identified levonorgestrel (13β-ethyl-17α-ethynyl-19-nortestosterone) as the active component of the mixture. Levonorgestrel was first studied in humans by 1970, and was introduced for medical use in Germany as a combined birth control pill with ethinylestradiol under the brand name Neogynon in August 1970. A more widely used formulation, containing lower doses of ethinylestradiol and levonorgestrel, was introduced under the brand name Microgynon by 1973. In addition to combined formulations, levonorgestrel was introduced as a progestogen-only pill under the brand names Microlut by 1972 and Microval by 1974. Many other formulations and brand names of levonorgestrel-containing birth control pills have also been marketed.
Levonorgestrel, taken alone in a single high dose, was first evaluated as a form of emergency contraception in 1973. It was the second progestin to be evaluated for such purposes, following a study of quingestanol acetate in 1970. In 1974, the Yuzpe regimen, which consisted of high doses of a combined birth control pill containing ethinylestradiol and norgestrel, was described as a method of emergency contraception by A. Albert Yuzpe and colleagues, and saw widespread interest. Levonorgestrel-only emergency contraception was introduced under the brand name Postinor by 1978. Ho and Kwan published the first study comparing levonorgestrel only and the Yuzpe regimen as methods of emergency contraception in 1993 and found that they had similar effectiveness but that levonorgestrel alone was better-tolerated. In relation to this, the Yuzpe regimen has largely been replaced as a method of emergency contraception by levonorgrestrel-only preparations. Levonorgestrel-only emergency contraception was approved in the United States under the brand name Plan B in 1999, and has also been marketed widely elsewhere throughout the world under other brand names such as Levonelle and NorLevo in addition to Postinor. In 2013, the Food and Drug Administration approved Plan B One-Step for sale over-the-counter in the United States without a prescription or age restriction.
Levonorgestrel has also been introduced for use as a progestogen-only intrauterine device under the brand names Mirena and Skyla among others, as a progestogen-only birth control implant under the brand names Norplant and Jadelle, as a combined oral tablet with estradiol valerate for menopausal hormone therapy under the brand name Klimonorm, and as a combined transdermal patch with estradiol for menopausal hormone therapy under the brand name Climara Pro. Ester prodrugs of levonorgestrel such as levonorgestrel acetate and levonorgestrel butanoate have been developed and studied as other forms of birth control such as long-acting progestogen-only injectable contraceptives and contraceptive vaginal rings, but have not been marketed for medical use. | 0 | Theoretical and Fundamental Chemistry |
As the result of substrate effects producing preferred crystallite orientations, pronounced textures tend to occur in thin films. Modern technological devices to a large extent rely on polycrystalline thin films with thicknesses in the nanometer and micrometer ranges. This holds, for instance, for all microelectronic and most optoelectronic systems or sensoric and superconducting layers. Most thin film textures may be categorized as one of two different types: (1) for so-called fiber textures the orientation of a certain lattice plane is preferentially parallel to the substrate plane; (2) in biaxial textures the in-plane orientation of crystallites also tend to align with respect to the sample. The latter phenomenon is accordingly observed in nearly epitaxial growth processes, where certain crystallographic axes of crystals in the layer tend to align along a particular crystallographic orientation of the (single-crystal) substrate.
Tailoring the texture on demand has become an important task in thin film technology. In the case of oxide compounds intended for transparent conducting films or surface acoustic wave (SAW) devices, for instance, the polar axis should be aligned along the substrate normal. Another example is given by cables from high-temperature superconductors that are being developed as oxide multilayer systems deposited on metallic ribbons. The adjustment of the biaxial texture in YBaCuO layers turned out as the decisive prerequisite for achieving sufficiently large critical currents.
The degree of texture is often subjected to an evolution during thin film growth and the most pronounced textures are only obtained after the layer has achieved a certain thickness. Thin film growers thus require information about the texture profile or the texture gradient in order to optimize the deposition process. The determination of texture gradients by x-ray scattering, however, is not straightforward, because different depths of a specimen contribute to the signal. Techniques that allow for the adequate deconvolution of diffraction intensity were developed only recently. | 1 | Applied and Interdisciplinary Chemistry |
Beauty products are now widely available from dedicated internet-only retailers, who have more recently been joined online by established outlets, including major department stores and traditional brick-and-mortar beauty retailers.
Like most industries, cosmetic companies resist regulation by government agencies. In the U.S., the Food and Drug Administration (FDA) does not approve or review cosmetics, although it does regulate the colors that can be used in hair dyes. Cosmetic companies are not required to report injuries resulting from use of their products.
Although modern makeup has been used mainly by women traditionally, gradually an increasing number of males are using cosmetics usually associated to women to enhance their own facial features. Concealer is commonly used by cosmetic-conscious men. Cosmetics brands are releasing cosmetic products especially tailored for men, and men are using such products more commonly. There is some controversy over this, however, as many feel that men who wear makeup are neglecting traditional gender roles, and do not view men wearing cosmetics in a positive light. Others, however, view this as a sign of increasing gender equality and feel that men also have the right to enhance their facial features with cosmetics if women do.
Today the market of cosmetics has a different dynamic compared to the 20th century. Some countries are driving this economy:
* Japan: Japan is the second largest market in the world. Regarding the growth of this market, cosmetics in Japan have entered a period of stability. However, the market situation is quickly changing. Now consumers can access a lot of information on the Internet and choose many alternatives, opening up many opportunities for newcomers entering the market, looking for chances to meet the diverse needs of consumers. The size of the cosmetics market for 2010 was 2286 billion yen on the basis of the value of shipments by brand manufacturer. With a growth rate of 0.1%, the market was almost unchanged from the previous year.
* Russia: One of the most interesting emerging markets, the 5th largest in the world in 2012, the Russian perfumery and cosmetics market has shown the highest growth of 21% since 2004, reaching US$13.5 billion.
* South Korea: South Korea's cosmetic industry is on the rise with its creations, light ingredients, and aesthetic packages. In 2020, the market amassed $6.8 billion with a $2.6 billion loss due to COVID-19. The total export of products and trade increased by 16 percent with France being the largest exporter followed by the United States and Japan. Skincare products remain to be the largest imported items at 34.17 percent along with perfumes and haircare products being other large, imported goods in 2021.
With the imposition of lockdowns due to the COVID-19 pandemic and the consequent wariness to return to salons, trends that imitate salon procedures started to emerge, such as more complicated home skin-care regimens, hair color preserving products, and beauty tools. Early in the pandemic, sales on makeup essentials, like foundation and lipstick, decreased by up to 70% because of quarantining and face-covering mandates.
In Latin America's cosmetic and personal-care industry, it has been increasing significantly and become much more diverse. Within the industry, the thought of sustainability in products are considered to find alternatives to silicone and palm sourced additives. Clariant being one of the companies producing such products. One item used in products is epseama derived from seaweed. The ingredient serves as an anti-aging agent in skin products. | 1 | Applied and Interdisciplinary Chemistry |
Coacervate ( or ) is an aqueous phase rich in macromolecules such as synthetic polymers, proteins or nucleic acids. It forms through liquid-liquid phase separation (LLPS), leading to a dense phase in thermodynamic equilibrium with a dilute phase. The dispersed droplets of dense phase are also called coacervates, micro-coacervates or coacervate droplets. These structures draw a lot of interest because they form spontaneously from aqueous mixtures and provide stable compartmentalization without the need of a membrane.
The term coacervate was coined in 1929 by Dutch chemist Hendrik G. Bungenberg de Jong and Hugo R. Kruyt while studying lyophilic colloidal dispersions. The name is a reference to the clustering of colloidal particles, like bees in a swarm. The concept was later borrowed by Russian biologist Alexander I. Oparin to describe the proteinoid microspheres proposed to be primitive cells (protocells) on early Earth. Coacervate-like protocells are at the core of the Oparin-Haldane hypothesis.
A reawakening of coacervate research was seen in the 2000s, starting with the recognition in 2004 by scientists at the University of California, Santa Barbara (UCSB) that some marine invertebrates (such as the sandcastle worm) exploit complex coacervation to produce water-resistant biological adhesives. A few years later in 2009 the role of liquid-liquid phase separation was further recognized to be involved in the formation of certain membraneless organelles by the biophysicists Clifford Brangwynne and Tony Hyman. Liquid organelles share features with coacervate droplets and fueled the study of coacervates for biomimicry. | 0 | Theoretical and Fundamental Chemistry |
Heap leach mining works well for large volumes of low grade ores, as reduced metallurgical treatment (comminution) of the ore is required in order to extract an equivalent amount of minerals when compared to milling. The significantly reduced processing costs are offset by the reduced yield of usually approximately 60-70%. The amount of overall environmental impact caused by heap leaching is often lower than more traditional techniques. It also requires less energy consumption to use this method, which many consider to be an environmental alternative. | 1 | Applied and Interdisciplinary Chemistry |
*GB772534A Improvements in or relating to titanium base alloys
*CH457874A Verfahren zur Wärmebehandlung einer Titanlegierung
*GB929931A Titanium-base alloys and their heat treatment
*US3007824A Method of heat treating a ti-be alloy
*US3118828A Electrode structure with titanium alloy base
*FI35168A Sätt att framställa en elektrod
*DE1112838B Verfahren zum Oberflaechenhaerten von (ª‡ú½ª‰) Ti-Legierungen | 1 | Applied and Interdisciplinary Chemistry |
Norşuntepe is a tell, or archaeological settlement mound, in Elazığ Province (Turkey). The site was occupied between the Chalcolithic and Iron Age and is now partially submerged by Lake Keban. It was excavated between 1968 and 1974. | 1 | Applied and Interdisciplinary Chemistry |
The Danishefsky Taxol total synthesis in organic chemistry is an important third Taxol synthesis published by the group of Samuel Danishefsky in 1996 two years after the first two efforts described in the Holton Taxol total synthesis and the Nicolaou Taxol total synthesis. Combined they provide a good insight in the application of organic chemistry in total synthesis.
Danishefsky's route to Taxol has many similarities with that of Nicolaou. Both are examples of convergent synthesis with a coupling of the A and the C ring from two precursors. The main characteristic of the Danishefsky variant is the completion of the oxetane D ring onto the cyclohexanol C ring prior to the construction of the 8-membered B ring. The most prominent starting material is the (+) enantiomer of the Wieland-Miescher ketone. This compound is commercially available as a single enantiomer and the single chiral group present in this molecule is able to drive the entire sequence of organic reactions to a single optically active Taxol endproduct. The final step, the tail addition is identical to that of Nicolaou and is based on Ojima chemistry.
In terms of raw material shopping, this taxol molecule consists of the aforementioned Wieland-Miescher ketone, 2-methyl-3-pentanone, lithium aluminium hydride, osmium tetroxide, phenyllithium, pyridinium chlorochromate, the Corey-Chaykovsky reagent and acryloyl chloride. Key chemical transformations are the Johnson-Corey-Chaykovsky reaction and the Heck reaction. | 0 | Theoretical and Fundamental Chemistry |
The equilibrium constant for the reaction is related to ΔG° by the relation:
where T is the absolute temperature and R is the gas constant. A positive value of ΔG° therefore implies
so that starting from molar stoichiometric quantities such a reaction would move backwards toward equilibrium, not forwards.
Nevertheless, endergonic reactions are quite common in nature, especially in biochemistry and physiology. Examples of endergonic reactions in cells include protein synthesis, and the Na/K pump which drives nerve conduction and muscle contraction. | 0 | Theoretical and Fundamental Chemistry |
Copper tubing is most often used for supply of hot and cold water, and as refrigerant line in HVAC systems. There are two basic types of copper tubing, soft copper and rigid copper. Copper tubing is joined using flare connection, compression connection, or solder. Copper offers a high level of resistance to corrosion, but is becoming very costly. | 1 | Applied and Interdisciplinary Chemistry |
The iron–sulfur world hypothesis is a set of proposals for the origin of life and the early evolution of life advanced in a series of articles between 1988 and 1992 by Günter Wächtershäuser, a Munich patent lawyer with a degree in chemistry, who had been encouraged and supported by philosopher Karl R. Popper to publish his ideas. The hypothesis proposes that early life may have formed on the surface of iron sulfide minerals, hence the name. It was developed by retrodiction (making a "prediction" about the past) from extant biochemistry (non-extinct, surviving biochemistry) in conjunction with chemical experiments. | 1 | Applied and Interdisciplinary Chemistry |
An alternative, catalyst-free method for transesterification uses supercritical methanol at high temperatures and pressures in a continuous process. In the supercritical state, the oil and methanol are in a single phase, and reaction occurs spontaneously and rapidly. The process can tolerate water in the feedstock, free fatty acids are converted to methyl esters instead of soap, so a wide variety of feedstocks can be used. Also the catalyst removal step is eliminated.
High temperatures and pressures are required, but energy costs of production are similar or less than catalytic production routes. | 0 | Theoretical and Fundamental Chemistry |
These materials are prepared by treating graphite with a strong oxidant or a strong reducing agent:
The reaction is reversible.
The host (graphite) and the guest X interact by charge transfer. An analogous process is the basis of commercial lithium-ion batteries.
In a graphite intercalation compound not every layer is necessarily occupied by guests. In so-called stage 1 compounds, graphite layers and intercalated layers alternate and in stage 2 compounds, two graphite layers with no guest material in between alternate with an intercalated layer. The actual composition may vary and therefore these compounds are an example of non-stoichiometric compounds. It is customary to specify the composition together with the stage. The layers are pushed apart upon incorporation of the guest ions. | 0 | Theoretical and Fundamental Chemistry |
In prehistory gold could be found in several areas of Europe; the Carpathian region, Iberia, south-western France, Brittany, Britain and Ireland. The latter in particular had rich gold reserves, and as such has been labelled an "ancient El Dorado". Across the world, and in many cultures, gold has been highly valued as a precious metal, in part because of its rarity and also because of its properties; for instance, unlike copper it is malleable, flexible and homogenous, and can be worked by hammering, rather than having to be worked through casting, annealing or soldering. Any products made from gold do not corrode, but instead have what has been described as an "intrinsic beauty", with many prehistoric peoples probably ascribing gold items a "symbolic as well as a decorative function". | 1 | Applied and Interdisciplinary Chemistry |
Plasmids replicate to produce many plasmid molecules in each host bacterial cell. The number of copies of each plasmid in a bacterial cell is determined by the replication origin, which is the position within the plasmid molecule where DNA replication is initiated. Most binary vectors have a higher number of plasmid copies when they replicate in E. coli; however, the plasmid copy-number is usually lower when the plasmid is resident within Agrobacterium tumefaciens.
Plasmids can also be replicated using the polymerase chain reaction (PCR). | 1 | Applied and Interdisciplinary Chemistry |
Natural cloning is the production of clones without the involvement of genetic engineering techniques. It may occur accidentally in the case of identical twins, which are formed when a fertilized egg splits, creating two or more embryos that carry almost identical DNA. It may also be part of asexual reproduction, which is a process where a single parent organism produces genetically identical offspring by itself.
Cloning is a natural form of reproduction that has allowed life forms to spread for hundreds of millions of years. It is a reproduction method used by plants, fungi, and bacteria, and is also the way that clonal colonies reproduce themselves. Examples of these organisms include blueberry plants, Hazel trees, the Pando trees, the Kentucky coffeetree, Myrica, and the American sweetgum.
If artificial cloning and natural cloning both lead to the same result, which is the formation of a clone, that is, an organism with identical or nearly identical genes to another organism, then the plight of This creation is very different between the two creatures. The main difference between the two is that natural cloning does not involve any human intervention, whereas artificial cloning is a genetic engineering technique.
Natural cloning occurs through a variety of natural mechanisms, from single-celled organisms to complex multicellular organisms. Some of the mechanisms are explored and used into plants and animals as binary fission, Budding, Fragmentation, parthenogenesis. | 1 | Applied and Interdisciplinary Chemistry |
Hemiacetals and hemiketals may be thought of as intermediates in the reaction between alcohols and aldehydes or ketones, with the final product being an acetal or a ketal:
:RC=O + ROH ⇌ RC(OH)(OR)
:RC(OH)(OR) + ROH ⇌ RC(OR') + HO
Usually, the second reaction is unfavorable. In the presence of a dehydrating agent, it proceeds. | 0 | Theoretical and Fundamental Chemistry |
Governments worldwide have created provisions for granting access to drugs prior to approval for patients who have exhausted all alternative treatment options and do not match clinical trial entry criteria. Often grouped under the labels of compassionate use, expanded access, or named patient supply, these programs are governed by rules which vary by country defining access criteria, data collection, promotion, and control of drug distribution.
Within the United States, pre-approval demand is generally met through treatment IND (investigational new drug) applications (INDs), or single-patient INDs. These mechanisms, which fall under the label of expanded access programs, provide access to drugs for groups of patients or individuals residing in the US. Outside the US, Named Patient Programs provide controlled, pre-approval access to drugs in response to requests by physicians on behalf of specific, or "named", patients before those medicines are licensed in the patients home country. Through these programs, patients are able to access drugs in late-stage clinical trials or approved in other countries for a genuine, unmet medical need, before those drugs have been licensed in the patients home country.
Patients who have not been able to get access to drugs in development have organized and advocated for greater access. In the United States, ACT UP formed in the 1980s, and eventually formed its Treatment Action Group in part to pressure the US government to put more resources into discovering treatments for AIDS and then to speed release of drugs that were under development.
The Abigail Alliance was established in November 2001 by Frank Burroughs in memory of his daughter, Abigail. The Alliance seeks broader availability of investigational drugs on behalf of terminally ill patients.
In 2013, BioMarin Pharmaceutical was at the center of a high-profile debate regarding expanded access of cancer patients to experimental drugs. | 1 | Applied and Interdisciplinary Chemistry |
In metalloproteins, metal ions are usually coordinated by nitrogen, oxygen or sulfur centers belonging to amino acid residues of the protein. These donor groups are often provided by side-chains on the amino acid residues. Especially important are the imidazole substituent in histidine residues, thiolate substituents in cysteine residues, and carboxylate groups provided by aspartate. Given the diversity of the metalloproteome, virtually all amino acid residues have been shown to bind metal centers. The peptide backbone also provides donor groups; these include deprotonated amides and the amide carbonyl oxygen centers. Lead(II) binding in natural and artificial proteins has been reviewed.
In addition to donor groups that are provided by amino acid residues, many organic cofactors function as ligands. Perhaps most famous are the tetradentate N macrocyclic ligands incorporated into the heme protein. Inorganic ligands such as sulfide and oxide are also common. | 1 | Applied and Interdisciplinary Chemistry |
The Bialecki ring was patented in 1974 by Polish chemical engineer from Kraków Zbigniew Białecki rings are an improved version of Raschig rings. The rings may be injection moulded of plastics or press-formed from metal sheet without welding. Specific surface area of filling ranges between 60 and 440 m/m. | 1 | Applied and Interdisciplinary Chemistry |
Changing the conditions of the reaction solvent can allow separation of phases for product removal, or single phase for reaction. Rapid diffusion accelerates diffusion controlled reactions. Temperature and pressure can tune the reaction down preferred pathways, e.g., to improve yield of a particular chiral isomer. There are also significant environmental benefits over conventional organic solvents. Industrial syntheses that are performed at supercritical conditions include those of polyethylene from supercritical ethene, isopropyl alcohol from supercritical propene, 2-butanol from supercritical butene, and ammonia from a supercritical mix of nitrogen and hydrogen. Other reactions were, in the past, performed industrially in supercritical conditions, including the synthesis of methanol and thermal (non-catalytic) oil cracking. Because of the development of effective catalysts, the required temperatures of those two processes have been reduced and are no longer supercritical. | 0 | Theoretical and Fundamental Chemistry |
Several metal objects similar to those in the Kfar Monash hoard were found in this general area of the Levant. They were subject to metallurgical analysis, and generally dated to the Early Bronze Age. For example, objects from Ashkelon-Afridar, and from Tell esh-Shuna (the Jordan Valley) were seen as similar. Also the axes from early EB I Yiftah’el are seen as relevant.
Kfar Monash objects were also dated, based on typological considerations, to EB IB, similarly to the axes from Tel Beth Shean.
The study of Kfar Monash hoard indicated that some of them were made of unalloyed copper. The source of this unalloyed copper was found likely to be in Wadi Feynan, in southern Jordan. Such unalloyed copper was apparently mainly used for the production of tools.
Other objects were made using a CuAsNi alloy. This is the copper-arsenic-nickel alloy that is especially characteristic of Chalcolithic period Arslantepe in Eastern Anatolia (the upper Euphrates region). Nevertheless, the adzes that were made of this alloy were determined to be of "an Egyptian type".
Objects from Arslantepe using such polymetallic ores are mainly ascribed to Level VIA (3400–3000 BCE), dating to the Uruk period. | 1 | Applied and Interdisciplinary Chemistry |
The Curtin–Hammett principle is used to explain the selectivity ratios for some stereoselective reactions. | 0 | Theoretical and Fundamental Chemistry |
The B3 DNA binding domain (DBD) is a highly conserved domain found exclusively in transcription factors (≥40 species) () combined with other domains (). It consists of 100-120 residues, includes seven beta strands and two alpha helices that form a DNA-binding pseudobarrel protein fold (); it interacts with the major groove of DNA. | 1 | Applied and Interdisciplinary Chemistry |
Electrochemical engineering --
Electrodialysis --
Electrokinetic phenomena --
Electrodeposition --
Electrolysis --
Electrolytic reduction --
Electroplating --
Electrostatic precipitation --
Electrowinning --
Emulsion --
Energy --
Engineering --
Engineering economics --
Enzymatic reaction -- | 1 | Applied and Interdisciplinary Chemistry |
The terms "defect" and "" refer to two specific and separate things in castings. Defects are defined as conditions in a casting that must be corrected or removed, or the casting must be rejected. Discontinuities, also known as "imperfections", are defined as "interruptions in the physical continuity of the casting". Therefore, if the casting is less than perfect, but still useful and in tolerance, the imperfections should be deemed "discontinuities". | 1 | Applied and Interdisciplinary Chemistry |
Italian Paracelsianism and chemical medicine from the mid-sixteenth century to the mid-seventeenth century, developed institutionally and intellectually with the introduction of chemical remedies in Italy. Paracelsian views were accepted wherever alchemy and practical chemistry were predominant, as in the Medici court in Florence. In Italy, Germany, England and France royal patronage supported Paracelsianism and new medicines were adopted by distillers, apothecaries and physicians. During this time, Sala advanced on Paracelsianism through his publishing in the new "chemical" medicine and the analysis of Vitriol, which he dedicated to the banker Bonaventura von Bodeck. The principle in chemistry that the names of a compound should indicate its constituents was recognised in Salas suggestion that the residue of the calcination of green vitriol (i.e. ferric oxide) might be called Substantia Ferrea Vitrioli as an improvement on the Paracelsan colcothar'. | 1 | Applied and Interdisciplinary Chemistry |
The epoxidation of ethylene involves its reaction with oxygen. According to a reaction mechanism suggested in 1974 at least one ethylene molecule is totally oxidized for every six that are converted to ethylene oxide:
The direct reaction of oxygen with alkenes is useful only for this epoxide. Modified heterogeneous silver catalysts are typically employed. Other alkenes fail to react usefully, even propylene, though TS-1 supported Au catalysts can perform propylene epoxidation selectively. | 0 | Theoretical and Fundamental Chemistry |
(AD 450(?)–1500)
Utilitarian and ceremonial objects; objects of personal adornment
#Chipal, Guatemala
#Chutixtiox, Guatemala
#Copán, Honduras
#Kaminaljuyú, Guatemala
#Motagua River valley, Guatemala
#Los Naranjos, Honduras
#Nebaj, Guatemala
#Quemistlá "Bell Caves", Honduras
#Quiriguá, Guatemala
#San Augustín Acasaguastlán, Guatemala
#Tajumulco, Guatemala
#Tazumal, El Salvador
#Zacualpa, Guatemala
#Zaculeu, Guatemala | 1 | Applied and Interdisciplinary Chemistry |
The ISI identified cold fusion as the scientific topic with the largest number of published papers in 1989, of all scientific disciplines. The Nobel Laureate Julian Schwinger declared himself a supporter of cold fusion in the fall of 1989, after much of the response to the initial reports had turned negative. He tried to publish his theoretical paper "Cold Fusion: A Hypothesis" in Physical Review Letters, but the peer reviewers rejected it so harshly that he felt deeply insulted, and he resigned from the American Physical Society (publisher of PRL) in protest.
The number of papers sharply declined after 1990 because of two simultaneous phenomena: first, scientists abandoned the field; second, journal editors declined to review new papers. Consequently, cold fusion fell off the ISI charts. Researchers who got negative results turned their backs on the field; those who continued to publish were simply ignored. A 1993 paper in Physics Letters A was the last paper published by Fleischmann, and "one of the last reports [by Fleischmann] to be formally challenged on technical grounds by a cold fusion skeptic."
The Journal of Fusion Technology (FT) established a permanent feature in 1990 for cold fusion papers, publishing over a dozen papers per year and giving a mainstream outlet for cold fusion researchers. When editor-in-chief George H. Miley retired in 2001, the journal stopped accepting new cold fusion papers. This has been cited as an example of the importance of sympathetic influential individuals to the publication of cold fusion papers in certain journals.
The decline of publications in cold fusion has been described as a "failed information epidemic". The sudden surge of supporters until roughly 50% of scientists support the theory, followed by a decline until there is only a very small number of supporters, has been described as a characteristic of pathological science. The lack of a shared set of unifying concepts and techniques has prevented the creation of a dense network of collaboration in the field; researchers perform efforts in their own and in disparate directions, making the transition to "normal" science more difficult.
Cold fusion reports continued to be published in a few journals like Journal of Electroanalytical Chemistry and Il Nuovo Cimento. Some papers also appeared in Journal of Physical Chemistry, Physics Letters A, International Journal of Hydrogen Energy, and a number of Japanese and Russian journals of physics, chemistry, and engineering. Since 2005, Naturwissenschaften has published cold fusion papers; in 2009, the journal named a cold fusion researcher to its editorial board. In 2015 the Indian multidisciplinary journal Current Science published a special section devoted entirely to cold fusion related papers.
In the 1990s, the groups that continued to research cold fusion and their supporters established (non-peer-reviewed) periodicals such as Fusion Facts, Cold Fusion Magazine, Infinite Energy Magazine and New Energy Times to cover developments in cold fusion and other fringe claims in energy production that were ignored in other venues. The internet has also become a major means of communication and self-publication for CF researchers. | 0 | Theoretical and Fundamental Chemistry |
Claire Vallance attended Marlborough Girls College in Blenheim, New Zealand. She then studied Chemistry, Physics, Mathematics, and Music at the University of Canterbury, where she completed a B.Sc.(hons) degree in 1995, graduating first in her year. She studied for a Ph.D. under the supervision of Peter Harland, working in gas-phase molecular dynamics, and graduated in early 1999. Upon completion of her studies, she returned to Oxford to take up a Violette and Samuel Glasstone Fellowship in the Physical and Theoretical Chemistry Laboratory and a Junior Research Fellowship at St. Catherines College. | 0 | Theoretical and Fundamental Chemistry |
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