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Derived from ribose, a pentose, pentosidine forms fluorescent cross-links between the arginine and lysine residues in collagen. It is formed in a reaction of the amino acids with the Maillard reaction products of ribose.
Although it is present only in trace concentrations among tissue proteins, it is useful for assessing cumulative damage to
proteins—advanced glycation endproducts—by non-enzymatic browning reactions with carbohydrates. | 1 | Applied and Interdisciplinary Chemistry |
Steroid 21-hydroxylase is localized in microsomes of endoplasmic reticulum membranes within adrenal cortex. It is one of three microsomal steroidogenic cytochrome P450 enzymes, the others being steroid 17-hydroxylase and aromatase.
Unlike other enzymes of the cytochrome P450 superfamily of enzymes that are expressed in multiple tissues, with most abundant expression in the liver, in adult humans steroid 21-hydroxylase, along with steroid 11β-hydroxylase and aldosterone synthase, is almost exclusively expressed in the adrenal gland.
the main subcellular location for the encoded protein in human cells is not known, and is pending cell analysis. | 1 | Applied and Interdisciplinary Chemistry |
There are several technological problems in designing and constructing a hyper-velocity wind tunnel:
*supply of high temperatures and pressures for times long enough to perform a measurement
*reproduction of equilibrium conditions
*structural damage produced by overheating
*fast instrumentation
*power requirements to run the tunnel
Simulations of a flow at 5.5 km/s, 45 km altitude would require tunnel temperatures of as much as 9000 K, and a pressure of 3 GPa. | 1 | Applied and Interdisciplinary Chemistry |
*Bailyn, M. (1994). A Survey of Thermodynamics, American Institute of Physics Press, New York, .
*Callen, H.B. (1960/1985). Thermodynamics and an Introduction to Thermostatistics, (1st edition 1960) 2nd edition 1985, Wiley, New York, .
* A translation may be found [http://neo-classical-physics.info/uploads/3/0/6/5/3065888/caratheodory_-_thermodynamics.pdf here]. Also a mostly reliable [https://books.google.com/books?id=xwBRAAAAMAAJ&q=Investigation+into+the+foundations translation is to be found] at Kestin, J. (1976). The Second Law of Thermodynamics, Dowden, Hutchinson & Ross, Stroudsburg PA..
*Giles, R. (1964). Mathematical Foundations of Thermodynamics, Macmillan, New York.
*Guggenheim, E.A. (1949/1967). Thermodynamics. An Advanced Treatment for Chemists and Physicists, fifth revised edition, North-Holland, Amsterdam.
*Guggenheim, E.A. (1949). Statistical basis of thermodynamics, Research, 2: 450–454.
*Gyarmati, I. (1967/1970). Non-equilibrium Thermodynamics. Field Theory and Variational Principles, translated from the 1967 Hungarian by E. Gyarmati and W.F. Heinz, Springer-Verlag, New York.
*Haase, R. (1971). Survey of Fundamental Laws, chapter 1 of Thermodynamics, pages 1–97 of volume 1, ed. W. Jost, of Physical Chemistry. An Advanced Treatise, ed. H. Eyring, D. Henderson, W. Jost, Academic Press, New York, lcn 73–117081.
*Kelvin, Lord (1857). On the alteration of temperature accompanying changes of pressure in fluids, [https://archive.org/stream/mathematicaland03kelvgoog#page/n258/mode/2up Proc. Roy. Soc., June].
*Landsberg, P.T. (1961). Thermodynamics with Quantum Statistical Illustrations, Interscience, New York.
*Lieb, E.H., Yngvason, J. (1999). The physics and mathematics of the second law of thermodynamics, Physics Reports, 314: 1–96, p. 14.
*Planck, M. (1887). Ueber das Princip der Vermehrung der Entropie, Annalen der Physik und Chemie, new series 30: 562–582.
*Planck, M., (1897/1903). [https://archive.org/details/treatiseonthermo00planrich Treatise on Thermodynamics], translated by A. Ogg, Longmans, Green, & Co., London.
*Planck, M. (1935). Bemerkungen über Quantitätsparameter, Intenstitätsparameter und stabiles Gleichgewicht, Physica, 2: 1029–1032.
*Tisza, L. (1966). Generalized Thermodynamics, M.I.T Press, Cambridge MA.
*Uffink, J. (2001). Bluff your way in the second law of thermodynamics, Stud. Hist. Phil. Mod. Phys., 32(3): 305–394, publisher Elsevier Science. | 0 | Theoretical and Fundamental Chemistry |
In November 1807, he attended the Paris lectures of the phrenologists Gall and Spurzheim; and, in 1828, published a review on Gall, Spurzheim, and Phrenology. Spurzheim was so impressed with Chenevixs review that he sought (and was granted) permission to immediately re-print the article as a pamphlet, with 12-page appendix of his (Spurzheims) own notes.
In Paris, in 1816, he met Abbé Faria, who reawakened an interest in animal magnetism that had been dormant since Chenevixs visit to Rotterdam in 1797. In 1828, on a visit to Ireland, he began to practise mesmerism. He wrote extensively of his experiences in a series of papers published in the London Medical and Physical Journal' in 1829.
Also in 1829, he gave a series of lectures and demonstrations of mesmerism in London that were attended by such eminent medical men as Sir Benjamin Brodie, William Prout, Henry Holland, Henry Earle, and John Elliotson. | 1 | Applied and Interdisciplinary Chemistry |
In one study, seven-membered rings were constructed in a tandem 5-exo-dig addition reaction / Claisen rearrangement:
A 6-endo-dig pattern was observed in an allene - alkyne 1,2-addition / Nazarov cyclization tandem catalysed by a gold compound:
A 5-endo-dig ring closing reaction was part of a synthesis of (+)-Preussin: | 0 | Theoretical and Fundamental Chemistry |
Backscattering is the principle behind radar systems. In weather radar, backscattering is proportional to the 6th power of the diameter of the target multiplied by its inherent reflective properties, provided the wavelength is larger than the particle diameter (Rayleigh scattering). Water is almost 4 times more reflective than ice but droplets are much smaller than snow flakes or hail stones. So the backscattering is dependent on a mix of these two factors. The strongest backscatter comes from hail and large graupel (solid ice) due to their sizes, but non-Rayleigh (Mie scattering) effects can confuse interpretation. Another strong return is from melting snow or wet sleet, as they combine size and water reflectivity. They often show up as much higher rates of precipitation than actually occurring in what is called a brightband. Rain is a moderate backscatter, being stronger with large drops (such as from a thunderstorm) and much weaker with small droplets (such as mist or drizzle). Snow has rather weak backscatter. Dual polarization weather radars measure backscatter at horizontal and vertical polarizations to infer shape information from the ratio of the vertical and horizontal signals. | 0 | Theoretical and Fundamental Chemistry |
Agostic interactions are best demonstrated by crystallography. Neutron diffraction data have shown that C−H and M┄H bond distances are 5-20% longer than expected for isolated metal hydride and hydrocarbons. The distance between the metal and the hydrogen is typically 1.8–2.3 Å, and the M┄H−C angle is in the range of 90°–140°. The presence of a H NMR signal that is shifted upfield from that of a normal aryl or alkane, often to the region normally assigned to hydride ligands. The coupling constant J is typically lowered to 70–100 Hz versus the 125 Hz expected for a normal sp carbon–hydrogen bond. | 0 | Theoretical and Fundamental Chemistry |
GC–MS can analyze the particles from a human body in order to help link a criminal to a crime. The analysis of fire debris using GC–MS is well established, and there is even an established American Society for Testing and Materials (ASTM) standard for fire debris analysis. GCMS/MS is especially useful here as samples often contain very complex matrices and results, used in court, need to be highly accurate. | 0 | Theoretical and Fundamental Chemistry |
In condensed matter physics, a supersolid is a spatially ordered material with superfluid properties. In the case of helium-4, it has been conjectured since the 1960s that it might be possible to create a supersolid. Starting from 2017, a definitive proof for the existence of this state was provided by several experiments using atomic Bose–Einstein condensates. The general conditions required for supersolidity to emerge in a certain substance are a topic of ongoing research. | 0 | Theoretical and Fundamental Chemistry |
STRA6 can be found at high levels in various tissues including: the choroid plexus, the brain microvascular, tesis, the spleen, kidney, eye, the placenta, and the female reproductive tract. However, it is surprisingly not found in liver tissue where Vitamin A (retinol) is primarily stored. Because of its importance in Vitamin A transport, STRA6 mutations are more commonly associated with problems with eye such as a reduction in retinal thickness and shortening of the inner and outer segments of rod photoreceptors. Therefore, as might be expected, STRA6 mutations result in a number of different abnormalities of the eye such as Microphthalmia, Anophthalmia, and Coloboma.
However, STRA6 is clearly vital for more than just eye development as it is expressed in many different tissues detailed above. Other disorders that result from STRA6 mutations include pulmonary dysgenesis, cardiac malformations, and mental retardation. In fact, research has shown that homozygous mutations in human STRA6 gene can lead to Matthew-Wood syndrome, which is a combination of all the mentioned disorders. In this respect, STRA6 mutations can be particularly fatal during the embryonic stage.
STRA6 has also been associated with facilitating insulin resistance. This is because STRA6 signaling results in activation of transcription factor STAT5 target genes. One of these target genes is a suppressor of cytokine signaling 3 (SOCS3) which is a strong inhibitor of insulin signaling. As a result, STRA6 signaling suppresses the response to insulin by inhibiting the phosphorylation of the insulin receptor, IR, by an influx of insulin. In other words, increased levels of the RBP in obese animals (which will increase STRA6 activity) can facilitate insulin resistance. Due to this close relationship between STRA6 and insulin resistance, it has been demonstrated that single nucleotide polymorphisms in STRA6 are associated with Type 2 Diabetes. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, the term phosphonium (more obscurely: phosphinium) describes polyatomic cations with the chemical formula (where R is a hydrogen or an alkyl, aryl, or halide group). These cations have tetrahedral structures. The salts are generally colorless or take the color of the anions. | 0 | Theoretical and Fundamental Chemistry |
An E1 elimination occurs when a proton adjacent to a positive charge leaves and generates a double bond.
Because initial formation of a cation is necessary for E1 reactions to occur, E1 reactions are often observed as side reactions to S1 mechanisms.
E1 eliminations proceed with the Elimination of a leaving group leading to the E designation. Because this mechanism proceeds with the initial dissociation of a single starting material forming a carbocation, this process is considered a uni-molecular reaction. The involvement of only 1 species in the initial phase of the reaction enhances the mechanistic designation to E1. | 0 | Theoretical and Fundamental Chemistry |
Snieckus was born in Kaunas, Lithuania in 1937. His family lived in Germany during World War II and in 1948 immigrated to Alberta, Canada. Snieckus received his bachelors degree in chemistry from University of Alberta in 1959, his masters degree from University of California, Berkeley in 1961, and his PhD from the University of Oregon in 1965 under the supervision of Virgil Boekelheide. He spent a year as a postdoctoral scholar at the National Research Council of Canada. | 0 | Theoretical and Fundamental Chemistry |
The fixation of by RuBisCO is a multi-step process. First, a molecule (that is not the molecule that is eventually fixed) attaches to the uncharged ε-amino group of lysine 201 in the active site to form a carbamate. This carbamate then binds to the magnesium ion (Mg) in RuBisCOs active site. A molecule of RuBP then binds to the Mg ion. The bound RuBP then loses a proton to form a reactive, enodiolate species. The rate-limiting step of the Calvin-Benson cycle is the addition of CO to this 2,3-enediol form of RuBP. This is the stage where the intrinsic KIE of Rubisco occurs because a new C-C bond is formed. The newly formed 2-carboxy-3-keto-D-arabinitol 1,5-bisphosphate molecule is then hydrated and cleaved to form two molecules of 3-phosphoglycerate (3 PGA). 3 PGA is then converted into hexoses to be used in the photosynthetic organisms central metabolism.
The isotopic substitutions that can occur in this reaction are for carbon, oxygen, and/or hydrogen, though currently only a significant isotope effect is seen for carbon isotope substitution. Isotopes are atoms that have the same number of protons but varying numbers of neutrons. "Lighter" isotopes (like the stable carbon-12 isotope) have a smaller overall mass, and "heavier" isotopes (like the stable carbon-13 isotope or radioactive carbon-14 isotope) have a larger overall mass. Stable isotope geochemistry is concerned with how varying chemical and physical processes preferentially enrich or deplete stable isotopes. Enzymes like RuBisCO cause isotopic fractionation because molecules containing lighter isotopes have higher zero-point energies (ZPE), the lowest possible quantum energy state for a given molecular arrangement. For this reaction, CO has a lower ZPE than CO and sits lower in the potential energy well of the reactants. When enzymes catalyze chemical reactions, the lighter isotope is preferentially selected because it has a lower activation energy and is thus more energetically favorable to overcome the high potential-energy transition state and proceed through the reaction. Here, CO has a lower activation energy so more CO than CO goes through the reaction, resulting in the product (3 PGA) being lighter. | 0 | Theoretical and Fundamental Chemistry |
* Assumes that each annular ring is independent of every other annular ring.
* Does not account for wake expansion.
* Does not account for tip losses, though correction factors can be included.
* Does not account for yaw, though it can be made to do so.
* Based on steady flow (non-turbulent). | 1 | Applied and Interdisciplinary Chemistry |
A prominent enol ether is phosphoenol pyruvate.
The enzyme chorismate mutase catalyzes the Claisen rearrangement of the enol ether called chorismate to prephenate, an intermediate in the biosynthesis of phenylalanine and tyrosine.
Batyl alcohol and related glycyl ethers are susceptible to dehydrogenation catalyzed unsaturases to give the vinyl ethers called plasmalogens: | 0 | Theoretical and Fundamental Chemistry |
Platinum-based antineoplastic drugs (informally called platins) are chemotherapeutic agents used to treat cancer. Their active moieties are coordination complexes of platinum. These drugs are used to treat almost half of people receiving chemotherapy for cancer. In this form of chemotherapy, commonly used drugs include cisplatin, oxaliplatin, and carboplatin, but several have been proposed or are under development. Addition of platinum-based chemotherapy drugs to chemoradiation in women with early cervical cancer seems to improve survival and reduce risk of recurrence.
In total, these drugs can cause a combination of more than 40 specific side effects which include neurotoxicity, which is manifested by peripheral neuropathies including polyneuropathy. | 1 | Applied and Interdisciplinary Chemistry |
RCCM lattices behave as an elastic solid in both tension and compression. They offer both a linear regime and a nonlinear super-elastic deformation mode a modulus an order of magnitude greater than for an ultralight material (12.3 megapascals at a density of 7.2 mg per cubic centimeter). Bulk properties can be predicted from component measurements and deformation modes determined by the placement of part types. Site locations are locally constrained, yielding structures that merge desirable features of carbon fiber composites, cellular materials and additive manufacturing.
Nonlinear elastic behavior derives from a multi-axial elastic instability of the lattice, a complex coordinated elastic buckling of the strut members. The resulting geometry is similar to a Jahn–Teller distortion of an octahedral complex with respect to orientation about the octahedral centers. Elastic folding or pleating can occur in three dimensions, likely a coordinated antisymmetric twisting stress response and/or plastic deformation. | 0 | Theoretical and Fundamental Chemistry |
The value of imaging lies in the ability to resolve spatial heterogeneities in solid-state or gel/gel-like samples. Imaging a liquid or even a suspension has limited use as constant sample motion serves to average spatial information, unless ultra-fast recording techniques are employed as in fluorescence correlation microspectroscopy or FLIM observations where a single molecule may be monitored at extremely high (photon) detection speed. High-throughput experiments (such as imaging multi-well plates) of liquid samples can however provide valuable information. In this case, the parallel acquisition of thousands of spectra can be used to compare differences between samples, rather than the more common implementation of exploring spatial heterogeneity within a single sample.
Similarly, there is no benefit in imaging a truly homogeneous sample, as a single point spectrometer will generate the same spectral information. Of course the definition of homogeneity is dependent on the spatial resolution of the imaging system employed. For MIR imaging, where wavelengths span from 3-10 micrometres, objects on the order of 5 micrometres may theoretically be resolved. The sampled areas are limited by current experimental implementations because illumination is provided by the interferometer. Raman imaging may be able to resolve particles less than 1 micrometre in size, but the sample area that can be illuminated is severely limited. With Raman imaging, it is considered impractical to image large areas and, consequently, large samples. FT-NIR chemical/hyperspectral imaging usually resolves only larger objects (>10 micrometres), and is better suited for large samples because illumination sources are readily available. However, FT-NIR microspectroscopy was recently reported to be capable of about 1.2 micron (micrometer) resolution in biological samples Furthermore, two-photon excitation FCS experiments were reported to have attained 15 nanometer resolution on biomembrane thin films with a special coincidence photon-counting setup. | 0 | Theoretical and Fundamental Chemistry |
The study of interactomes is called interactomics. The basic unit of a protein network is the protein–protein interaction (PPI). While there are numerous methods to study PPIs, there are relatively few that have been used on a large scale to map whole interactomes.
The yeast two hybrid system (Y2H) is suited to explore the binary interactions among two proteins at a time. Affinity purification and subsequent mass spectrometry is suited to identify a protein complex. Both methods can be used in a high-throughput (HTP) fashion. Yeast two hybrid screens allow false positive interactions between proteins that are never expressed in the same time and place; affinity capture mass spectrometry does not have this drawback, and is the current gold standard. Yeast two-hybrid data better indicates non-specific tendencies towards sticky interactions rather while affinity capture mass spectrometry better indicates functional in vivo protein–protein interactions. | 1 | Applied and Interdisciplinary Chemistry |
Lucretius introduced the concept of the javelin argument in his discourse of space and how it can be bound. He explained:
:For whatever bounds it, that thing must itself be bounded likewise; and to this bounding thing there must be a bound again, and so on for ever and ever throughout all immensity. Suppose, however, for a moment, all existing space to be bounded, and that a man runs forward to the uttermost borders, and stands upon the last verge of things, and then hurls forward a winged javelin,— suppose you that the dart, when hurled by the vivid force, shall take its way to the point the darter aimed at, or that something will take its stand in the path of its flight, and arrest it? For one or other of these things must happen. There is a dilemma here that you never can escape from.
The javelin argument has two implications. If the hurled javelin flew onwards unhindered, it meant that the man running was not at the edge of the universe because there is something beyond the edge where the weapon flew. On the other hand, if it did not, the man was still not at the edge because there must be an obstruction beyond that stopped the javelin. However, the argument assumes incorrectly that a finite universe must necessarily have a "limit" or edge. The argument fails in the case that the universe might be shaped like the surface of a hypersphere or torus. (Consider a similar fallacious argument that the Earths surface must be infinite in area: because otherwise one could go to the Earths edge and throw a javelin, proving that the Earth's surface continued wherever the javelin hit the ground.) | 1 | Applied and Interdisciplinary Chemistry |
A risk for periphyton stems from urbanization. Increased turbidity levels associated with urban sprawl can smother periphyton causing its detachment from the rocks on which it lives. It can be important for the clearance of harmful chemicals and reducing turbidity. | 1 | Applied and Interdisciplinary Chemistry |
Siderophores (Greek: "iron carrier") are small, high-affinity iron-chelating compounds that are secreted by microorganisms such as bacteria and fungi. They help the organism accumulate iron. Although a widening range of siderophore functions is now being appreciated, siderophores are among the strongest (highest affinity) Fe binding agents known. Phytosiderophores are siderophores produced by plants. | 1 | Applied and Interdisciplinary Chemistry |
In multivariate calculus, a differential or differential form is said to be exact or perfect (exact differential), as contrasted with an inexact differential, if it is equal to the general differential for some differentiable function in an orthogonal coordinate system (hence is a multivariable function whose variables are independent, as they are always expected to be when treated in multivariable calculus).
An exact differential is sometimes also called a total differential, or a full differential, or, in the study of differential geometry, it is termed an exact form.
The integral of an exact differential over any integral path is path-independent, and this fact is used to identify state functions in thermodynamics. | 0 | Theoretical and Fundamental Chemistry |
* Brazil: Classified as a weapon by Federal Act n° 3665/2000 (Regulation for Fiscalization of Controlled Products). Only law enforcement officers and private security agents with a recognized Less Lethal Weapons training certificate can carry it.
* Colombia: Can be sold without any kind of restriction to anyone older than 14 years.
** Use has not been inducted on the law enforcement officer's arsenal. | 1 | Applied and Interdisciplinary Chemistry |
Medieval Buddhist atomism, flourishing around the 7th century, was very different from the atomist doctrines taught in early Buddhism. Medieval Buddhist philosophers Dharmakirti and Dignāga considered atoms to be point-sized, durationless, and made of energy. In discussing the two systems, Fyodor Shcherbatskoy (1930) stresses their commonality, the postulate of "absolute qualities" (guna-dharma) underlying all empirical phenomena.
Still later, the Abhidhammattha-sangaha, a text dated to the 11th or 12th century, postulates the existence of rupa-kalapa, imagined as the smallest units of the physical world, of varying elementary composition. Invisible under normal circumstances, the rupa-kalapa are said to become visible as a result of meditative samadhi. | 1 | Applied and Interdisciplinary Chemistry |
The Petasis reagent is prepared by the salt metathesis reaction of methylmagnesium chloride or methyllithium with titanocene dichloride:
: CpTiCl + 2 CHMgCl → CpTi(CH) + 2 MgCl
This compound is used for the transformation of carbonyl groups to terminal alkenes. It exhibits similar reactivity to the Tebbe reagent and Wittig reaction. Unlike the Wittig reaction, the Petasis reagent can react with a wide range of aldehydes, ketones and esters. The Petasis reagent is also very air stable, and is commonly used in solution with toluene or THF.
The Tebbe reagent and the Petasis reagent share a similar reaction mechanism. The active olefinating reagent, CpTiCH, is generated in situ upon heating. With the organic carbonyl, this titanium carbene forms a four membered oxatitanacyclobutane that releases the terminal alkene.
In contrast to the Tebbe reagent, homologs of the Petasis reagent are relatively easy to prepare by using the corresponding alkyllithium instead of methyllithium, allowing the conversion of carbonyl groups to alkylidenes. | 0 | Theoretical and Fundamental Chemistry |
Positron emission tomography for bone imaging, as an in vivo tracer technique, allows the measurement of the regional concentration of radioactivity proportional to the image pixel values averaged over a region of interest (ROI) in bones. Positron emission tomography is a functional imaging technique that uses [F]NaF radiotracer to visualise and quantify regional bone metabolism and blood flow. [F]NaF has been used for imaging bones for the last 60 years. This article focuses on the pharmacokinetics of [F]NaF in bones, and various semi-quantitative and quantitative methods for quantifying regional bone metabolism using [F]NaF PET images. | 1 | Applied and Interdisciplinary Chemistry |
The stoichiometric structure and mass-conservation properties of biochemical pathways gives rise to a series of theorems or relationships between the control coefficients and the control coefficients and elasticities. There are a large number of such relationships depending on the pathway configuration (e.g. linear, branched or cyclic) which have been documented and discovered by various authors. The term theorem has been used to describe these relationships because they can be proved in terms of more elementary concepts. The operational proofs in particular are of this nature.
The most well known of these theorems are the summation theorems for the control coefficients and the connectivity theorems which relate control coefficients to the elasticities. The focus of this page are the connectivity theorems.
When deriving the summation theorems, a thought experiment was conducted that involved manipulating enzyme activities such that concentrations were unaffected but fluxes changed. The connectivity theorems use the opposite thought experiment, that is enzyme activities are changed such that concentrations change but fluxes are unchanged. This is an important observation that highlights the orthogonal nature of these two sets of theorem.
As with the summation theorems, the connectivity theorems can also be proved using more rigorous mathematical approaches involving calculus and linear algebra. Here the more intuitive and operational proofs will be used to prove the connectivity theorems. | 1 | Applied and Interdisciplinary Chemistry |
The complete quantum mechanical description was first performed by Bethe and Heitler. They assumed plane waves for electrons which scatter at the nucleus of an atom, and derived a cross section which relates the complete geometry of that process to the frequency of the emitted photon. The quadruply differential cross section, which shows a quantum mechanical symmetry to pair production, is
where is the atomic number, the fine-structure constant, the reduced Planck's constant and the speed of light. The kinetic energy of the electron in the initial and final state is connected to its total energy or its momenta via
where is the mass of an electron. Conservation of energy gives
where is the photon energy. The directions of the emitted photon and the scattered electron are given by
where is the momentum of the photon.
The differentials are given as
The absolute value of the virtual photon between the nucleus and electron is
The range of validity is given by the Born approximation
where this relation has to be fulfilled for the velocity of the electron in the initial and final state.
For practical applications (e.g. in Monte Carlo codes) it can be interesting to focus on the relation between the frequency of the emitted photon and the angle between this photon and the incident electron. Köhn and Ebert integrated the quadruply differential cross section by Bethe and Heitler over and and obtained:
with
and
However, a much simpler expression for the same integral can be found in (Eq. 2BN) and in (Eq. 4.1).
An analysis of the doubly differential cross section above shows that electrons whose kinetic energy is larger than the rest energy (511 keV) emit photons in forward direction while electrons with a small energy emit photons isotropically. | 0 | Theoretical and Fundamental Chemistry |
The relative permittivity of air changes with temperature, humidity, and barometric pressure. Sensors can be constructed to detect changes in capacitance caused by changes in the relative permittivity. Most of this change is due to effects of temperature and humidity as the barometric pressure is fairly stable. Using the capacitance change, along with the measured temperature, the relative humidity can be obtained using engineering formulas. | 0 | Theoretical and Fundamental Chemistry |
First, adhesive from the HybriWell is peeled off and the HybriWell is attached over the area of the slide printed with the gelatin-DNA solution. Second, 200ul of transfection mix is pipetted into one of the HybriWell ports; the mixture will distribute evenly over the array. The array is then incubated, with temperature and time dependent on the cell types used. Third, the transfection mix is pipetted away and the HybriWell removed with a thin-tipped forceps. Fourth, the printed slide treated with transfection reagent is placed into a square dish with the printed side facing up. Fifth, the harvested cells are gently poured onto the slides (not on the printed areas). Finally, the dish is placed in a 37°C, 5% CO humidified incubator and incubated overnight. | 1 | Applied and Interdisciplinary Chemistry |
A nocebo effect is said to occur when negative expectations of the patient regarding a treatment cause the treatment to have a more negative effect than it otherwise would have. For example, when a patient anticipates a side effect of a medication, they can experience that effect even if the "medication" is actually an inert substance. The complementary concept, the placebo effect, is said to occur when positive expectations improve an outcome. The nocebo effect is also said to occur in someone who falls ill owing to the erroneous belief that they were exposed to a toxin, e.g. a physical phenomenon they believe is harmful, such as EM radiation.
Both placebo and nocebo effects are presumably psychogenic, but they can induce measurable changes in the body. One article that reviewed 31 studies on nocebo effects reported a wide range of symptoms that could manifest as nocebo effects, including nausea, stomach pains, itching, bloating, depression, sleep problems, loss of appetite, sexual dysfunction, and severe hypotension. | 1 | Applied and Interdisciplinary Chemistry |
The article that proposed the law attributes it to four main causes:
* The better than the Beatles problem: The sense that new drugs only have modest incremental benefit over drugs already widely considered as successful, such as Lipitor, and treatment effects on top of already effective treatments are smaller than treatment effects versus placebo. The smaller size of these treatment effects mandates an increase in clinical trial sizes to show the same level of efficacy. This problem was phrased as "better than the Beatles" to highlight the fact that it would be difficult to come up with new successful pop songs if all new songs had to be better than the Beatles.
* The cautious regulator problem: The progressive lowering of risk tolerance seen by drug regulatory agencies that makes research and development (R&D) both costlier and harder. After older drugs (such as Thalidomide or Vioxx) are removed from the market due to safety reasons, the bar on safety for new drugs is increased.
* The throw money at it tendency: The tendency to add human resources and other resources to R&D, which may lead to project overrun.
* The basic research–brute force bias: The tendency to overestimate the ability of advances in basic research and brute force screening methods to show a molecule as safe and effective in clinical trials. From the 1960s to the 1990s (and later), drug discovery has shifted from whole-animal classical pharmacology testing methods (phenotypic screening) to reverse pharmacology target-approaches that result in the discovery of drugs that may tightly bind with high-affinity to target proteins, but which still often fail in clinical trials due to an under-appreciation of the complexity of the whole organism. Furthermore, drug discovery techniques have shifted from small-molecule and iterative low-throughput search strategies to target-based high-throughput screening (HTS) of large compound libraries. But despite being faster and cheaper, HTS approaches may be less productive.
While some suspect a lack of "low-hanging fruit" as a significant contribution to Erooms law, this may be less important than the four main causes, as there are still many decades worth of new potential drug targets relative to the number of targets which already have been exploited, even if the industry exploits 4 to 5 new targets per year. There is also space to explore selectively non-selective drugs (or "dirty drugs") that interact with several molecular targets, and which may be particularly effective as central nervous system (CNS) therapeutics, even though few of them have been introduced in the last few decades.
As of 2018, academic spinouts and small biotech startups have surpassed Big Pharma with respect to the number of best-selling drugs approved, with 24/30 (80%) originating outside of Big Pharma. | 1 | Applied and Interdisciplinary Chemistry |
The electronegativity of an atom changes depending on the hybridization of the orbital employed in bonding. Electrons in s orbitals are held more tightly than electrons in p orbitals. Hence, a bond to an atom that employs an sp hybrid orbital for bonding will be more heavily polarized to that atom when the hybrid orbital has more s character. That is, when electronegativities are compared for different hybridization schemes of a given element, the order holds (the trend should apply to non-integer hybridization indices as well). While this holds true in principle for any main-group element, values for the hybridization-specific electronegativity are most frequently cited for carbon. In organic chemistry, these electronegativities are frequently invoked to predict or rationalize bond polarities in organic compounds containing double and triple bonds to carbon. | 0 | Theoretical and Fundamental Chemistry |
Butyllithium is principally valued as an initiator for the anionic polymerization of dienes, such as butadiene. The reaction is called "carbolithiation":
:CHLi + CH=CH−CH=CH → CH−CH−CH=CH−CHLi
Isoprene can be polymerized stereospecifically in this way. Also of commercial importance is the use of butyllithium for the production of styrene-butadiene polymers. Even ethylene will insert into BuLi. | 0 | Theoretical and Fundamental Chemistry |
The amination of phosphorus trihalides occur sequentially, with each amination proceeding more slowly than the preceding:
:PCl + 2 HNMe → MeNPCl + [HNMe]Cl
:MeNPCl + 2 HNMe → (MeN)PCl + [HNMe]Cl
With bulky amines like diisopropylamine, the selectivity for the monosubstitution improves.
Commercially available aminophosphine chlorides include dimethylaminophosphorus dichloride and bis(dimethylamino)phosphorus chloride.
Related aminophosphine fluorides compounds are available from trifluorophosphine. The diphosphine MeN(PF) is prepared from methylamine:
:2 PF + 3 MeNH → MeN(PF) + 2 [MeNH]F
Me(PF) is used as a bridging ligand in organometallic chemistry.
Substituted aminophosphines are generally prepared from organophosphorus chlorides and amines. The method is used to prepare ligands for homogeneous catalysis. Chlorodiphenylphosphine and diethylamine react to give an aminophosphine:
:PhPCl + 2 HNEt → PhPNEt + [HNEt]Cl
Primary amines react with phosphorus(III) chlorides give aminophosphines with acidic α-NH centers:
:PhPCl + 2 HNR → PhPN(H)R + [HNR]Cl | 0 | Theoretical and Fundamental Chemistry |
SMAs find a variety of applications in civil structures such as bridges and buildings. In the form of rebars or plates, they can be used for flexural, shear and seismic strengthening of concrete and steel structures. Another application is Intelligent Reinforced Concrete (IRC), which incorporates SMA wires embedded within the concrete. These wires can sense cracks and contract to heal micro-sized cracks. Also the active tuning of structural natural frequency using SMA wires to dampen vibrations is possible, as well as the usage of SMA fibers in concrete. | 1 | Applied and Interdisciplinary Chemistry |
Assessments of the sustainability of paludiculture should take into account ecosystem services besides carbon sequestration and how paludiculture can be integrated with traditional farming practices. Peatlands can provide a number of other ecosystem services e.g. biodiversity conservation and water regulation. It is therefore important to protect this areas and restore degraded areas. To conserve, restore and improve management of peat lands is a cost efficient and relatively easy way to maintain ecosystem services. However, these the ecosystem services are not priced in a market and do not produce economic profit for the local communities. The drainage and cultivation, grazing, as well as peat mining on the other hand give the local communities short-term economic profits. It has therefore been argued that conservation and restoration, which has a significant and common value, needs to be subsidized by the state or the world at large.
Paludiculture is not focused on nature conservation but on production, but paludiculture and conservation may complement each other in a number of ways. 1) Paludiculture can be the starting point and an intermediate stage in the process of restoring a drained peatland. 2) Paludiculture can lower the cost of the conservation project by e.g. decrease the costs of biomass removal and establishment costs. 3) Areas with paludiculture practice can provide buffer zones around the conserved peat areas. 4) Areas with paludiculture in between conservation areas can provide corridors facilitating species migration. 5) Paludiculture may increase the acceptance by the affected stakeholder to rewet once drained peatland. The support of the local communities in rewetting project are often crucial.
The effect on greenhouse gas emissions of paludiculture is complex. On the one hand a higher water table will reduce the aerobic decomposition of peat and therefore the carbon dioxide emissions. But on the other hand the increased ground water table may increase anaerobic decomposition of organic matter or methanogenesis and therefore increase the emission of methane (CH), a short-lived but more potent greenhouse gas than CO. The emissions emanating from rewetted peatland with paludiculture will also be affected by the land-use in terms of type of use (agriculture, forestry, grazing etc.), but also in terms of used species and intensity. Traditional use of peatland has often less impact on the environment than industrial use has, but need not be sustainable in the long run and if used at a larger scale. | 1 | Applied and Interdisciplinary Chemistry |
Supercells are also commonly used in computational models of crystal defects to allow the use of periodic boundary conditions. | 0 | Theoretical and Fundamental Chemistry |
Herbivores consume ionone-containing carotenoids and convert those to retinal. Some species, including cattle and horses, have measurable amounts of beta-carotene circulating in the blood, and stored in body fat, creating yellow fat cells. Most species have white fat and no beta-carotene in circulation. | 1 | Applied and Interdisciplinary Chemistry |
The history of who first devised the process is unknown. What is known is that from 1870 onwards, a number of patents were filed for the process. Although all patents appear after 1870, it has been suggested that the process may have been discovered earlier, and the patents claimed a short time afterwards. The most well known patent holders are Frederick Shirley from the United States of America, whose patent dates to 1879, Erard and Round who were under the auspices of Stevens & Williams Ltd. whose patent is from 1889, John Sharling also of the USA, whose patent is from 1893 and Friedrich Deusch, the German inventor whose name is most associated with silver overlay today, whose patented the process in 1895 and displayed his work in 1907 at an exhibition in Bordeaux.
Deusch returned to Schwäbisch Gmünd in southern Germany where, in 1912, he founded his firm Deusch & Co. Deusch continued exhibiting his wares and gained the Gold Medal at the 1913 World Exposition in Ghent, Belgium.
With his presence, Schwäbisch Gmünd became the center of German silver overlay production. Schwäbisch Gmünd (about 20,000 inhabitants in that time) had a long tradition since the 16th century in the art of artists working with gold and silver. A school for applied arts existed there from an early date, which became a school for the precious metal industry in 1907.
In the 1920s almost 190 firms were involved in the precious metals industry. The presence of materials, artisans, and component suppliers in on place created an ideal environment for the industry to thrive.
After Deusch and Company, other firms specializing in silver overlay were founded. In particular, the firms of Friedrich Wilhelm Spahr and Alfred and Manfred Veyhl were established.
Parallel to the development of German silver overlay, silver overlay production was also initiated in the United States. | 1 | Applied and Interdisciplinary Chemistry |
Oxidative addition into cyclopropylimines gives a metalloenamine intermediate similar to oxidative addition to cyclopropylketones giving alkylmetalloenolates. These intermediates can also reaction with alpha-beta unsaturated ketones to give disubstituted cyclopentane products following reductive elimination.
With rhodium, the intermediate metalloenamine reacts with tethered alkynes. and alkenes to give cyclized products such as pyrroles and cyclohexenones, respectively. | 0 | Theoretical and Fundamental Chemistry |
Unlike the hydrogens on the carbon vertices, the hydrogens on the boron vertices are not acidic and do not react with strong bases. This is because boron is not as electronegative as carbon and thus the polarity of the B—H bonds is relatively low. Substitution at the boron vertices is still possible using halogenating agents through electrophilic substitution or photochemical reactions.
For example, the boron vertices at the 9 and 12 positions opposite to the carbon vertices can be iodinated using iodine and a catalytic amount of AlCl while in refluxing dichloromethane.
Exohedral halogenation leads to an increase in the electron withdrawing effect of the carborane which increases the acidity of the C—H bonds especially when the halogens are located at the 9, and 12 positions. Per-halogenation is also possible and when increasing the number of halide atoms, the π backdonation ability of the halide decreases allowing for the formation of intramolecular halide-halide noncovalent bonds.
Iodinated derivatives of carborane can be further modified to access boron alkylated products via a cross coupling reaction. This can be done by treating the halogenated carborane with a Grignard reagent in the presence of a phosphine palladium complex. The bromo and chloro compounds do not react under the same conditions. | 0 | Theoretical and Fundamental Chemistry |
;Dense gradation
:A dense gradation refers to a sample that is approximately of equal amounts of various sizes of aggregate. By having a dense gradation, most of the air voids between the material are filled with particles. A dense gradation will result in an even curve on the gradation graph.
;Narrow gradation
:Also known as uniform gradation, a narrow gradation is a sample that has aggregate of approximately the same size. The curve on the gradation graph is very steep, and occupies a small range of the aggregate.
;Gap gradation
:A gap gradation refers to a sample with very little aggregate in the medium size range. This results in only coarse and fine aggregate. The curve is horizontal in the medium size range on the gradation graph.
;Open gradation
:An open gradation refers an aggregate sample with very little fine aggregate particles. This results in many air voids, because there are no fine particles to fill them. On the gradation graph, it appears as a curve that is horizontal in the small size range.
;Rich gradation
:A rich gradation refers to a sample of aggregate with a high proportion of particles of small sizes. | 1 | Applied and Interdisciplinary Chemistry |
EAB sensors possess the potential to significantly advance our comprehension of metabolism, endocrinology, pharmacokinetics, and neurochemistry as valuable research tools. Specifically, these sensors offer improved resolution and more quantitative measurements of phenomena such as drug delivery, clearance, and the maintenance of metabolic homeostasis. With their capability for feedback control, EAB sensors also present unprecedented opportunities to elucidate the correlation between, for instance, plasma drug levels and subsequent clinical or behavioral responses. The simultaneous measurements performed by EAB sensors in multiple body locations can enhance our understanding of drug and metabolite transport within and between bodily compartments. Beyond in-body measurements, EAB sensors could be beneficial for real-time monitoring in cell culture applications, ranging from small-scale (e.g., "organ on a chip") to industrial scale (e.g., monitoring industrial bioreactors). They have already demonstrated utility in applications such as monitoring ATP release in astrocytes and detecting serotonin in cell culture using glass nanopipettes.
Aptamers, referred to as "chemical antibodies," are used in therapeutics and biosensing due to their specific recognition and binding capabilities toward target molecules. They offer advantages over classical antibodies as they are significantly lighter, easily penetrate intracellular targets, can be synthetically produced, are non-immunogenic, and exhibit stability. Aptamers excel in discerning proteins, demonstrating precision in diagnostics and therapeutics, and have applications in laboratory assays and separations, particularly in biomolecule purification, chiral separation, and biochemical assays. The ability of aptamers to undergo conformational changes makes them ideal for developing quenching-based biosensors, showcasing flexibility that antibodies lack. Unlike antibodies, which are prone to cross-reactivity and batch variations, aptamers offer customizable selectivity and stability. This is particularly evident in biosensor applications targeting low-molecular-weight entities like small molecules | 0 | Theoretical and Fundamental Chemistry |
The son of Spanish immigrants from the Province of León, more precisely from Cabreros del Río, Baró married the writer María Dhialma Tiberti. He completed his Associate of Science in Chemistry degree at the Otto Krause Technical School in Buenos Aires, in 1945. Afterward, he pursued his studies at Universidad de Buenos Aires from which he obtained a Bachelor of Science, followed by a PhD in Chemistry in 1961 at the Instituut voor Kernphysisch Onderzoek, in Amsterdam. In 1968, he conducted research on the production of radioisotopes in Bombay, India, organized by the International Atomic Energy Agency.
Baró was additionally a professor at several universities, such as Universidad de Buenos Aires, Universidad Nacional de La Plata, Universidad Nacional de Cuyo, Universidad Nacional de Rosario, and Universidad Nacional del Litoral. He was named Emeritus Researcher of the National Atomic Energy Commission in 2010, following 40 years of institutional work and reaching the rank of Director. He was also awararded a Doctor honoris causa in Radiochemistry from Higher University of San Andres, Bolivia, notably for his work in discovering new isotopes of ruthenium, rhodium, rhenium, tungsten, and osmium, and for the development of a contrast agent for Magnetic Resonance Imaging during retirement.
He was the Argentinian representative of the International Union of Pure and Applied Chemistry (IUPAC) for several years. In addition, he served as consultant for the Comisión de Energía Atómica de Bolivia, the Comisión Chilena de Energía Nuclear, the Instituto de Asuntos Nucleares de Colombia, the International Atomic Energy Agency in Asunción, Paraguay, and the Centro Atómico del Perú, and the government of Uruguay. | 0 | Theoretical and Fundamental Chemistry |
Solar energy conversion can impact not only just individual customers but whole communities. In a growing number of neighborhoods across America, the conventional model of independent, non-connected rooftop installations is being replaced by community-sized solar microgrids. The idea of “community solar” first became popular because of issues regarding energy storage. Because as of 2018 the wide-scale production of lithium-ion battery and other storage technologies lags the progress of rooftop PV installations, a main issue preventing a nationwide shift to rooftop solar energy generation is the lack of a reliable, single-home storage system that would provide contingencies for night-time energy use, cloud cover, curtailments and blackouts. Additionally, financing solar installations for single homes may be more difficult to secure given a smaller project scope and lack of access to funds. A viable alternative is to connect blocks of homes together in a community microgrid, using more proven large storage installations, thus lowering barriers to solar adoption. In some cases, a microgrid “web” is made by connecting each independent rooftop PV house to a greater storage facility. Other designs, primarily where rooftop installations are not possible, feature a large combined solar array + storage facility located on an adjacent field. As an added social impact, this form of installation makes solar energy economically viable for multi-family homes and historically low income neighborhoods. | 0 | Theoretical and Fundamental Chemistry |
The introduction of refrigeration allowed for the hygienic handling and storage of perishables, and as such, promoted output growth, consumption, and the availability of nutrition. The change in our method of food preservation moved us away from salts to a more manageable sodium level. The ability to move and store perishables such as meat and dairy led to a 1.7% increase in dairy consumption and overall protein intake by 1.25% annually in the US after the 1890s.
People were not only consuming these perishables because it became easier for they themselves to store them, but because the innovations in refrigerated transportation and storage led to less spoilage and waste, thereby driving the prices of these products down. Refrigeration accounts for at least 5.1% of the increase in adult stature (in the US) through improved nutrition, and when the indirect effects associated with improvements in the quality of nutrients and the reduction in illness is additionally factored in, the overall impact becomes considerably larger. Recent studies have also shown a negative relationship between the number of refrigerators in a household and the rate of gastric cancer mortality. | 0 | Theoretical and Fundamental Chemistry |
Polymers that can crystallize are (with the exception of PP) guarantee to obtain this effect, mainly due to their ordering capacity, which is reflected in the crystallinity, the crystals have affinity for their constituent elements and form new bonds these achieve anchoring forces that give stability to the temporary form. | 0 | Theoretical and Fundamental Chemistry |
As with oxidative addition, several mechanisms are possible with reductive elimination. The prominent mechanism is a concerted pathway, meaning that it is a nonpolar, three-centered transition state with retention of stereochemistry. In addition, an S2 mechanism, which proceeds with inversion of stereochemistry, or a radical mechanism, which proceeds with obliteration of stereochemistry, are other possible pathways for reductive elimination. | 0 | Theoretical and Fundamental Chemistry |
The earliest reported synthesis of a rotaxane in 1967 relied on the statistical probability that if two halves of a dumbbell-shaped molecule were reacted in the presence of a macrocycle that some small percentage would connect through the ring. To obtain a reasonable quantity of rotaxane, the macrocycle was attached to a solid-phase support and treated with both halves of the dumbbell 70 times and then severed from the support to give a 6% yield. However, the synthesis of rotaxanes has advanced significantly and efficient yields can be obtained by preorganizing the components utilizing hydrogen bonding, metal coordination, hydrophobic forces, covalent bonds, or coulombic interactions. The three most common strategies to synthesize rotaxane are "capping", "clipping", and "slipping", though others do exist. Recently, Leigh and co-workers described a new pathway to mechanically interlocked architectures involving a transition-metal center that can catalyse a reaction through the cavity of a macrocycle. | 0 | Theoretical and Fundamental Chemistry |
An increase in permeability usually indicates a more open structure in the rammed sand, and if the increase continues, it will lead to penetration-type defects and rough castings. A decrease in permeability indicates tighter packing and could lead to blows and pinholes. | 1 | Applied and Interdisciplinary Chemistry |
The most common glass scintillators are cerium-activated lithium or boron silicates. Since both lithium and boron have large neutron cross-sections, glass detectors are particularly well suited to the detection of thermal (slow) neutrons. Lithium is more widely used than boron since it has a greater energy release on capturing a neutron and therefore greater light output. Glass scintillators are however sensitive to electrons and γ rays as well (pulse height discrimination can be used for particle identification). Being very robust, they are also well-suited to harsh environmental conditions. Their response time is ≈10 ns, their light output is however low, typically ≈30% of that of anthracene. | 0 | Theoretical and Fundamental Chemistry |
Photoelectrochemistry has been intensively studied in the 1970-80s because of the first peak oil crisis. Because fossil fuels are non-renewable, it is necessary to develop processes to obtain renewable resources and use clean energy. Artificial photosynthesis, photoelectrochemical water splitting and regenerative solar cells are of special interest in this context. The photovoltaic effect was discovered by Alexandre Edmond Becquerel.
Heinz Gerischer, H. Tributsch, AJ. Nozik, AJ. Bard, A. Fujishima, K. Honda, PE. Laibinis, K. Rajeshwar, TJ Meyer, PV. Kamat, N.S. Lewis, R. Memming, John Bockris are researchers which have contributed a lot to the field of photoelectrochemistry. | 0 | Theoretical and Fundamental Chemistry |
Nitrate esters are typically prepared by condensation of nitric acid and the alcohol: For example, the simplest nitrate ester, methyl nitrate, is formed by reaction of methanol and nitric acid in the presence of sulfuric acid:
Formation of a nitrate ester is called a nitrooxylation (less commonly, nitroxylation). | 0 | Theoretical and Fundamental Chemistry |
According to historian of atomism Joshua Gregory, there was no serious work done with atomism from the time of Galen until Isaac Beeckman, Gassendi and Descartes resurrected it in the 17th century; "the gap between these two modern naturalists and the ancient Atomists marked "the exile of the atom" and "it is universally admitted that the Middle Ages had abandoned Atomism, and virtually lost it." | 1 | Applied and Interdisciplinary Chemistry |
When it was realized that some metals form two different binary compounds with the same nonmetal, the two compounds were often distinguished by using the ending -ic for the higher metal oxidation state and the ending -ous for the lower. For example, FeCl is ferric chloride and FeCl is ferrous chloride. This system is not very satisfactory (although sometimes still used) because different metals have different oxidation states which have to be learned: ferric and ferrous are +3 and +2 respectively, but cupric and cuprous are +2 and +1, and stannic and stannous are +4 and +2. Also, there was no allowance for metals with more than two oxidation states, such as vanadium with oxidation states +2, +3, +4, and +5.
This system has been largely replaced by one suggested by Alfred Stock in 1919 and adopted by IUPAC in 1940. Thus, FeCl was written as iron(II) chloride rather than ferrous chloride. The Roman numeral II at the central atom came to be called the "Stock number" (now an obsolete term), and its value was obtained as a charge at the central atom after removing its ligands along with the electron pairs they shared with it. | 0 | Theoretical and Fundamental Chemistry |
Knowles began his career in 1991 with a research fellowship at St Catharines College, Cambridge, before moving to New Zealand to work as a research and consultancy metallurgist for Industrial Research Ltd between 1993 and 1995. He then returned to the University of Cambridge in 1995 to take up a post as lecturer in Mechanical Properties of Materials, and was also appointed assistant director of Research of the Rolls-Royce University Technology Centre. His research at that time focussed on fatigue and creep in nickel based superalloys including high stress low' temperature creep anisotropy in single crystals. In 2001 Knowles returned to New Zealand to take up the role of CTO at MPT Solutions, where he continued to publish academic papers with a developing interest in crystal plasticity. In 2006 he was appointed Global Research Leader for Materials at Shell Global Solutions, based in Amsterdam looking into materials for LNG and gas to liquid technologies. In 2010, he moved to Atkins as their materials authority in the energy sector, focussing on offshore wind turbine foundations and nuclear Advanced Gas Reactors. In 2016 he took up a post at the University of Bristol as Professor of Nuclear Engineering, and co-director of the South West Nuclear Hub.
Knowles was named Chief Executive of the Henry Royce Institute for advanced materials research in 2019. He has continued his research as the principal investigator on the Sindri prosperity partnership EPSRC project, working with a number of university partners alongside EDF and UKAEA, which is focussed on characterising and modelling the meso to macro scale mechanics of alloys. In particular, he is interested in researching the use of data-centric methods to interrogate and describe material mechanical behaviour which can then be used to predict the condition of components of nuclear power plants. | 1 | Applied and Interdisciplinary Chemistry |
When two or more types of monomers undergo addition polymerization, the resulting polymer is an addition copolymer. Saran wrap, formed from polymerization of vinyl chloride and vinylidene chloride, is an addition copolymer. | 0 | Theoretical and Fundamental Chemistry |
The MRL is usually determined by repeated (on the order of 10) field trials, where the crop has been treated according to good agricultural practice (GAP) and an appropriate pre harvest interval or withholding period has elapsed. For many pesticides this is set at the limit of determination (LOD) – since only major pesticides have been evaluated and understanding of acceptable daily intake (ADI) is incomplete (i.e. producers or public bodies have not submitted MRL data – often because these were not required in the past). LOD can be considered a measure of presence/absence, but certain residues may not be quantifiable at very low levels. For this reason the limit of quantification (LOQ) is often used instead of the LOD. As a rule of thumb the LOQ is approximately two times the LOD. For substances that are not included in any of the annexes in EU regulations, a default MRL of 0.01 mg/kg normally applies.
It follows that adoption of GAP at the farm level must be a priority, and includes the withdrawal of obsolete pesticides. With increasingly sensitive detection equipment, a certain amount of pesticide residue will often be measured following field use. In the current regulatory environment, it would be wise for cocoa producers to focus only on pest control agents that are permitted for use in the EU and US. It should be stressed that MRLs are set on the basis of observations and not on ADIs. | 1 | Applied and Interdisciplinary Chemistry |
Typically FbFPs have an excitation maximum at a wavelength of approximately 450 nm (blue light) and a second distinct excitation peak around 370 nm (UV-A light). The main emission peak is at approx. 495 nm, with a shoulder around 520 nm. One variant of Pp2FbFP (Q116V) exhibits a 10 nm blue shift in both the excitation and emission spectra. Rationally designed variants of iLOV and CagFbFP exhibit 6 and 7 nm red shifts, respectively. | 1 | Applied and Interdisciplinary Chemistry |
As the Haber–Weiss reaction depends on the presence of both Fe and Fe in solution, its kinetics is influenced by the respective solubilities of both species whose are directly function of the solution pH. As Fe is about 100 times less soluble than Fe in natural waters at near-neutral pH, the ferric ion concentration is the limiting factor for the reaction rate. The reaction can only proceed with a fast enough rate under sufficiently acidic conditions. At high pH, under alkaline conditions, the reaction considerably slows down because of the precipitation of Fe(OH) which notably lowers the concentration of the Fe species in solution.
Moreover, the pH value also directly influences the acid-base dissociation equilibrium involving the hydroperoxyl and the superoxide radicals (pK = 4.7) as mentioned above. | 1 | Applied and Interdisciplinary Chemistry |
The liquid droplet radiator (LDR) or previously termed liquid droplet stream radiator is a proposed lightweight radiator for the dissipation of waste heat generated by power plants, propulsion or spacecraft systems in space. | 0 | Theoretical and Fundamental Chemistry |
:V09IX01 Iobenguane (I)
:V09IX02 Iobenguane (I)
:V09IX03 Iodine (I) CC49-monoclonal antibody
:V09IX04 Fludeoxyglucose (F)
:V09IX05 Fluorodopa (F)
:V09IX06 Sodium fluoride (F)
:V09IX07 Fluorocholine (F)
:V09IX08 Fluoroethylcholine (F)
:V09IX09 Gallium (Ga) edotreotide
:V09IX10 Fluoroethyl--tyrosine (F)
:V09IX11 Fluoroestradiol (F)
:V09IX12 Fluciclovine (F)
:V09IX13 Methionine (C)
:V09IX14 Gallium (Ga) gozetotide
:V09IX15 Copper (64Cu) dotatate
:V09IX16 Piflufolastat (F)
:V09IX17 PSMA-1007 (F) | 1 | Applied and Interdisciplinary Chemistry |
The thermodynamic formalism allows that a system may have contact with several other systems at once, which may or may not also have mutual contact, the contacts having respectively different permeabilities. If these systems are all jointly isolated from the rest of the world those of them that are in contact then reach respective contact equilibria with one another.
If several systems are free of adiabatic walls between each other, but are jointly isolated from the rest of the world, then they reach a state of multiple contact equilibrium, and they have a common temperature, a total internal energy, and a total entropy. Amongst intensive variables, this is a unique property of temperature. It holds even in the presence of long-range forces. (That is, there is no "force" that can maintain temperature discrepancies.) For example, in a system in thermodynamic equilibrium in a vertical gravitational field, the pressure on the top wall is less than that on the bottom wall, but the temperature is the same everywhere.
A thermodynamic operation may occur as an event restricted to the walls that are within the surroundings, directly affecting neither the walls of contact of the system of interest with its surroundings, nor its interior, and occurring within a definitely limited time. For example, an immovable adiabatic wall may be placed or removed within the surroundings. Consequent upon such an operation restricted to the surroundings, the system may be for a time driven away from its own initial internal state of thermodynamic equilibrium. Then, according to the second law of thermodynamics, the whole undergoes changes and eventually reaches a new and final equilibrium with the surroundings. Following Planck, this consequent train of events is called a natural thermodynamic process. It is allowed in equilibrium thermodynamics just because the initial and final states are of thermodynamic equilibrium, even though during the process there is transient departure from thermodynamic equilibrium, when neither the system nor its surroundings are in well defined states of internal equilibrium. A natural process proceeds at a finite rate for the main part of its course. It is thereby radically different from a fictive quasi-static process that proceeds infinitely slowly throughout its course, and is fictively reversible. Classical thermodynamics allows that even though a process may take a very long time to settle to thermodynamic equilibrium, if the main part of its course is at a finite rate, then it is considered to be natural, and to be subject to the second law of thermodynamics, and thereby irreversible. Engineered machines and artificial devices and manipulations are permitted within the surroundings. The allowance of such operations and devices in the surroundings but not in the system is the reason why Kelvin in one of his statements of the second law of thermodynamics spoke of "inanimate" agency; a system in thermodynamic equilibrium is inanimate.
Otherwise, a thermodynamic operation may directly affect a wall of the system.
It is often convenient to suppose that some of the surrounding subsystems are so much larger than the system that the process can affect the intensive variables only of the surrounding subsystems, and they are then called reservoirs for relevant intensive variables. | 0 | Theoretical and Fundamental Chemistry |
A primer dimer is formed and amplified in three steps. In the first step, two primers anneal at their respective 3 ends (step I in the figure). If this construct is stable enough, the DNA polymerase will bind and extend the primers according to the complementary sequence (step II in the figure). An important factor contributing to the stability of the construct in step I is a high GC-content at the 3 ends and length of the overlap. The third step occurs in the next cycle, when a single strand of the product of step II is used as a template to which fresh primers anneal leading to synthesis of more PD product. | 1 | Applied and Interdisciplinary Chemistry |
Using the dielectric formalism, the IMFP can be calculated by solving the following integral:
with the minimum (maximum) energy loss (), the dielectric function , the energy loss function (ELF) and the smallest and largest momentum transfer . In general, solving this integral is quite challenging and only applies for energies above 100 eV. Thus, (semi)empirical formulas were introduced to determine the IMFP.
A first approach is to calculate the IMFP by an approximate form of the relativistic Bethe equation for inelastic scattering of electrons in matter. Equation holds for energies between 50 eV and 200 keV:
with
and
and the electron energy in eV above the Fermi level (conductors) or above the bottom of the conduction band (non-conductors). is the electron mass, the vacuum velocity of light, is the number of valence electrons per atom or molecule, describes the density (in ), is the atomic or molecular weight and , , and are parameters determined in the following. Equation calculates the IMFP and its dependence on the electron energy in condensed matter.
Equation was further developed to find the relations for the parameters , , and for energies between 50 eV and 2 keV:
Here, the bandgap energy is given in eV. Equation an are also known as the TTP-2M equations and are in general applicable for energies between 50 eV and 200 keV. Neglecting a few materials (diamond, graphite, Cs, cubic-BN and hexagonal BN) that are not following these equations (due to deviations in ), the TTP-2M equations show precise agreement with the measurements.
Another approach based on Equation to determine the IMFP is the S1 formula. This formula can be applied for energies between 100 eV and 10 keV:
with the atomic number (average atomic number for a compound), or ( is the heat of formation of a compound in eV per atom) and the average atomic spacing :
with the Avogadro constant and the stoichiometric coefficients and describing binary compounds . In this case, the atomic number becomes
with the atomic numbers and of the two constituents. This S1 formula shows higher agreement with measurements compared to Equation .
Calculating the IMFP with either the TTP-2M formula or the S1 formula requires different knowledge of some parameters. Applying the TTP-2M formula one needs to know , and for conducting materials (and also for non-conductors). Employing S1 formula, knowledge of the atomic number (average atomic number for compounds), and is required for conductors. If non-conducting materials are considered, one also needs to know either or .
An analytical formula for calculating the IMFP down to 50 eV was proposed in 2021. Therefore, an exponential term was added to an analytical formula already derived from that was applicible for energies down to 500 eV:
For relativistic electrons it holds:
with the electron velocity , and . denotes the velocity of light. and are given in nanometers. The constants in and are defined as following: | 0 | Theoretical and Fundamental Chemistry |
Imd signalling regulates a number of effector peptides and proteins that are produced en masse following immune challenge. This includes many of the major antimicrobial peptide genes of Drosophila, particularly: Diptericin, Attacin, Drosocin, Cecropin, and Defensin. The Imd pathway regulates hundreds of genes after infection, however the antimicrobial peptides play one of the most essential roles of Imd signalling in defence. Flies lacking multiple antimicrobial peptide genes succumb to infections by a broad suite of Gram-negative bacteria. Classical thinking suggested that antimicrobial peptides worked as a generalist cocktail in defence, where each peptide provided a small and somewhat redundant contribution. However Hanson and colleagues found that single antimicrobial peptide genes displayed an unexpectedly high degree of specificity for defence against specific microbes. The fly Diptericin A gene is essential for defence against the bacterium Providencia rettgeri (also suggested by an earlier evolutionary study). A second specificity is encoded by Diptericin B, which defends flies against Acetobacter bacteria of the fly microbiome. A third specificity is encoded by the gene Drosocin. Flies lacking Drosocin are highly susceptible to Enterobacter cloacae infection. The Drosocin gene itself encodes two peptides (named Drosocin and Buletin), wherein it is specifically the Drosocin peptide that is responsible for defence against E. cloacae, while the Buletin peptide instead mediates a specific defence against another bacterium, Providencia burhodogranariea. These works accompany others on antimicrobial peptides and effectors regulated by the Drosophila Toll pathway, which also display a specific importance in defence against certain fungi or bacteria.
This work on Drosophila immune antimicrobial peptides and effectors has greatly revised the former view that such peptides are generalist molecules. The modern interpretation is now that specific molecules might provide a somewhat redundant layer of defence, but also single peptides can have critical importance, individually, against relevant microbes. | 1 | Applied and Interdisciplinary Chemistry |
Any reaction in the domain of photogeochemistry, either observed in the environment or studied in the laboratory, may be broadly classified according to the nature of the materials involved.
# Reactions among naturally occurring compounds. Photogeochemistry, both observational and exploratory, is concerned with reactions among materials known to occur naturally, as this reflects what happens or may happen on Earth.
# Reactions in which one or more of the reactants are not known to occur naturally. Studies of reactions among materials related to naturally occurring materials may contribute to understanding of natural processes. These complementary studies are relevant to photogeochemistry in that they illustrate reactions that may have a natural counterpart. For example, it has been shown that soils, when irradiated, can generate reactive oxygen species and that clay minerals present in soils can accelerate the degradation of synthetic chemicals; it may therefore be postulated that naturally occurring compounds are similarly affected by sunlight acting on soil. The conversion of N to NH has been observed upon irradiation in the presence of the iron titanate FeTiO. While such a compound is not known to occur naturally, it is related to ilmenite (FeTiO) and pseudobrookite (FeTiO), and can form upon heating of ilmenite; this may imply a similar reaction with N for the naturally occurring minerals. | 0 | Theoretical and Fundamental Chemistry |
Monocarboranes are clusters with cages. The 12-vertex derivative is best studied, but several are known.
Typically they are prepared by the addition of one-carbon reagents to boron hydride clusters. One-carbon reagents include cyanide, isocyanides, and formaldehyde. For example, monocarbadodecaborate () is produced from decaborane and formaldehyde, followed by addition of borane dimethylsulfide.
Monocarboranes are precursors to weakly coordinating anions. | 0 | Theoretical and Fundamental Chemistry |
Hammond was born on April 4, 1833, in Grafton, Massachusetts, to Josiah and Anna Warren. One of his siblings, William Henry (1841–1908), followed him to Maine. He worked in Portland until his death, a few months after George, at the age of 67. His body was returned to the family's hometown of Grafton for interment.
He received an honorary degree of Master of Arts degree from Bowdoin College in 1900. | 1 | Applied and Interdisciplinary Chemistry |
HSP have been criticized for lacking the formal theoretical derivation of Hildebrand solubility parameters. All practical correlations of phase equilibrium involve certain assumptions that may or may not apply to a given system. In particular, all solubility parameter-based theories have a fundamental limitation that they apply only to associated solutions (i.e., they can only predict positive deviations from Raoults law): they cannot account for negative deviations from Raoults law that result from effects such as solvation (often important in water-soluble polymers) or the formation of electron donor acceptor complexes. Like any simple predictive theory, HSP are best used for screening with data used to validate the predictions. Hansen parameters have been used to estimate Flory-Huggins Chi parameters, often with reasonable accuracy.
The factor of 4 in front of the dispersion term in the calculation of Ra has been the subject of debate. There is some theoretical basis for the factor of four (see Ch 2 of Ref 1 and also. However, there are clearly systems (e.g. Bottino et al., "Solubility parameters of poly(vinylidene fluoride)" J. Polym. Sci. Part B: Polymer Physics 26(4), 785-79, 1988) where the regions of solubility are far more eccentric than predicted by the standard Hansen theory.
HSP effects can be over-ridden by size effects (small molecules such as methanol can give "anomalous results").
It has been shown that it is possible to calculate HSP via molecular dynamics techniques, though currently the polar and hydrogen bonding parameters cannot reliably be partitioned in a manner that is compatible with Hansen's values. | 0 | Theoretical and Fundamental Chemistry |
An induction coil is placed around a small section of the pipe at the bend point. It is then induction heated to between 800 and 2,200 degrees Fahrenheit (430 and 1,200 C). While the pipe is hot, pressure is placed on the pipe to bend it. The pipe can then be quenched with either air or water spray or be cooled against ambient air.
Induction bending is used to produce bends for a wide range of applications, such as (thin walled) pipe lines for both the upstream and down stream and on- and off shore segments of the petrochemical industry, large radius structural parts for the construction industry, thick walled, short radius bends for the power generating industry and city heating systems.
Big advantages of induction bending are:
* no need for mandrels
* bend radii and angles (1°-180°) can be freely selected
* highly accurate bend radii and angles
* accurate pipe spools can easily be produced
* significant savings can be obtained on field welds
* wide range of pipe sizes can be accommodated in one machine (1” OD thru 80”OD)
* excellent wall thinning and ovality values | 1 | Applied and Interdisciplinary Chemistry |
The various liquid-crystal phases (called mesophases together with plastic crystal phases) can be characterized by the type of ordering. One can distinguish positional order (whether molecules are arranged in any sort of ordered lattice) and orientational order (whether molecules are mostly pointing in the same direction). Liquid crystals are characterized by orientational order, but only partial or completely absent positional order. In contrast, materials with positional order but no orientational order are known as plastic crystals. Most thermotropic LCs will have an isotropic phase at high temperature: heating will eventually drive them into a conventional liquid phase characterized by random and isotropic molecular ordering and fluid-like flow behavior. Under other conditions (for instance, lower temperature), a LC might inhabit one or more phases with significant anisotropic orientational structure and short-range orientational order while still having an ability to flow.
The ordering of liquid crystals extends up to the entire domain size, which may be on the order of micrometers, but usually not to the macroscopic scale as often occurs in classical crystalline solids. However some techniques, such as the use of boundaries or an applied electric field, can be used to enforce a single ordered domain in a macroscopic liquid crystal sample. The orientational ordering in a liquid crystal might extend along only one dimension, with the material being essentially disordered in the other two directions. | 0 | Theoretical and Fundamental Chemistry |
The existence of backsplicing was first suggested in 2012. This backsplicing explains the genesis of circular RNAs resulting from the exact junction between the 3 boundary of an exon with the 5 boundary of an exon located upstream. In these exonic circular RNAs, the junction is a classic 3-5link.
The exclusion of intronic sequences during splicing can also leave traces, in the form of circular RNAs. In some cases, the intronic lariat is not destroyed and the circular part remains as a lariat-derived circRNA.In these lariat-derived circular RNAs, the junction is a 2-5link. | 1 | Applied and Interdisciplinary Chemistry |
Three types of spectra can be collected from a PIXE experiment:
# X-ray emission spectrum.
# Rutherford backscattering spectrum.
# Proton transmission spectrum. | 0 | Theoretical and Fundamental Chemistry |
Respiratory, allergic, or immune effects in infants or children are associated with man-made VOCs and other indoor or outdoor air pollutants.
Some VOCs, such as styrene and limonene, can react with nitrogen oxides or with ozone to produce new oxidation products and secondary aerosols, which can cause sensory irritation symptoms. VOCs contribute to the formation of tropospheric ozone and smog.
Health effects include eye, nose, and throat irritation; headaches, loss of coordination, nausea; and damage to the liver, kidney, and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans. Key signs or symptoms associated with exposure to VOCs include conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, dyspnea, declines in serum cholinesterase levels, nausea, vomiting, nose bleeding, fatigue, dizziness.
The ability of organic chemicals to cause health effects varies greatly from those that are highly toxic to those with no known health effects. As with other pollutants, the extent and nature of the health effect will depend on many factors including level of exposure and length of time exposed. Eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment are among the immediate symptoms that some people have experienced soon after exposure to some organics. At present, not much is known about what health effects occur from the levels of organics usually found in homes. | 0 | Theoretical and Fundamental Chemistry |
To solve a multi-objective optimization problem, it is necessary to convert the problem into a single objective optimization problem, by using adjustments, such as a weighted sum of objectives, or an ε-constraint method. The weighted sum approach gives a certain weight to the different objectives, and then factors in all these weights to form a single objective function that can be solved by single factor optimization. This method is not entirely satisfactory, because the weights cannot be correctly chosen, so this approach cannot find the optimal solution for all the original objectives. | 1 | Applied and Interdisciplinary Chemistry |
Strong bases catalyze hydroamination, an example being the ethylation of piperidine using ethene:
Such base catalyzed reactions proceed well with ethene but higher alkenes are less reactive. | 0 | Theoretical and Fundamental Chemistry |
Alkanediazonium salts are synthetically unimportant due to their extreme and uncontrolled reactivity toward S2/S1/E1 substitution. These cations are however of theoretical interest. Furthermore, methyldiazonium carboxylate is believed to be an intermediate in the methylation of carboxylic acids by diazomethane, a common transformation.
Loss of is both enthalpically and entropically favorable:
:, ΔH = −43 kcal/mol
:, ΔH = −11 kcal/mol
For secondary and tertiary alkanediazonium species, the enthalpic change is calculated to be close to zero or negative, with minimal activation barrier. Hence, secondary and (especially) tertiary alkanediazonium species are either unbound, nonexistent species or, at best, extremely fleeting intermediates.
The aqueous pK of methanediazonium () is estimated to be <10. | 0 | Theoretical and Fundamental Chemistry |
Side effects may include liver damage and nerve problems. Hyperthermia may also occur. Deaths have also resulted. | 1 | Applied and Interdisciplinary Chemistry |
Ferromagnetic resonance, or FMR, is coupling between an electromagnetic wave and the magnetization of a medium through which it passes. This coupling induces a significant loss of power of the wave. The power is absorbed by the precessing magnetization (Larmor precession) of the material and lost as heat. For this coupling to occur, the frequency of the incident wave must be equal to the precession frequency of the magnetization (Larmor frequency) and the polarization of the wave must match the orientation of the magnetization.
This effect can be used for various applications such as spectroscopic techniques or conception of microwave devices.
The FMR spectroscopic technique is used to probe the magnetization of ferromagnetic materials. It is a standard tool for probing spin waves and spin dynamics. FMR is very broadly similar to electron paramagnetic resonance (EPR), and also somewhat similar to nuclear magnetic resonance (NMR), except that FMR probes the sample magnetization resulting from the magnetic moments of dipolar-coupled but unpaired electrons, while NMR probes the magnetic moment of atomic nuclei that are screened by the atomic or molecular orbitals surrounding such nuclei of non-zero nuclear spin.
The FMR resonance is also the basis of various high-frequency electronic devices, such as resonance isolators or circulators. | 0 | Theoretical and Fundamental Chemistry |
In polymer chemistry, branching is the regular or irregular attachment of side chains to a polymer's backbone chain. It occurs by the replacement of a substituent (e.g. a hydrogen atom) on a monomer subunit by another covalently-bonded chain of that polymer; or, in the case of a graft copolymer, by a chain of another type. Branched polymers have more compact and symmetrical molecular conformations, and exhibit intra-heterogeneous dynamical behavior with respect to the unbranched polymers. In crosslinking rubber by vulcanization, short sulfur branches link polyisoprene chains (or a synthetic variant) into a multiple-branched thermosetting elastomer. Rubber can also be so completely vulcanized that it becomes a rigid solid, so hard it can be used as the bit in a smoking pipe. Polycarbonate chains can be crosslinked to form the hardest, most impact-resistant thermosetting plastic, used in safety glasses.
Branching may result from the formation of carbon-carbon or various other types of covalent bonds. Branching by ester and amide bonds is typically by a condensation reaction, producing one molecule of water (or HCl) for each bond formed.
Polymers which are branched but not crosslinked are generally thermoplastic. Branching sometimes occurs spontaneously during synthesis of polymers; e.g., by free-radical polymerization of ethylene to form polyethylene. In fact, preventing branching to produce linear polyethylene requires special methods. Because of the way polyamides are formed, nylon would seem to be limited to unbranched, straight chains. But "star" branched nylon can be produced by the condensation of dicarboxylic acids with polyamines having three or more amino groups. Branching also occurs naturally during enzymatically-catalyzed polymerization of glucose to form polysaccharides such as glycogen (animals), and amylopectin, a form of starch (plants). The unbranched form of starch is called amylose.
The ultimate in branching is a completely crosslinked network such as found in Bakelite, a phenol-formaldehyde thermoset resin. | 0 | Theoretical and Fundamental Chemistry |
In biochemistry and metabolism, beta oxidation (also β-oxidation) is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA. Acetyl-CoA enters the citric acid cycle, generating NADH and FADH, which are electron carriers used in the electron transport chain. It is named as such because the beta carbon of the fatty acid chain undergoes oxidation and is converted to a carbonyl group to start the cycle all over again. Beta-oxidation is primarily facilitated by the mitochondrial trifunctional protein, an enzyme complex associated with the inner mitochondrial membrane, although very long chain fatty acids are oxidized in peroxisomes.
The overall reaction for one cycle of beta oxidation is:
:C-acyl-CoA + FAD + NAD + HO + CoA → C-acyl-CoA + FADH + NADH + H + acetyl-CoA | 1 | Applied and Interdisciplinary Chemistry |
Although ethers resist hydrolysis, they are cleaved by hydrobromic acid and hydroiodic acid. Hydrogen chloride cleaves ethers only slowly. Methyl ethers typically afford methyl halides:
:ROCH + HBr → CHBr + ROH
These reactions proceed via onium intermediates, i.e. [RO(H)CH]Br.
Some ethers undergo rapid cleavage with boron tribromide (even aluminium chloride is used in some cases) to give the alkyl bromide. Depending on the substituents, some ethers can be cleaved with a variety of reagents, e.g. strong base.
Despite these difficulties the chemical paper pulping processes are based on cleavage of ether bonds in the lignin. | 0 | Theoretical and Fundamental Chemistry |
Dr. Kenneth B. Storey is among the top 2% of highly cited scientists in the world.
*[https://pubmed.ncbi.nlm.nih.gov/?term=storey+kb&sort=date&size=100 PubMed]
* [https://scholar.google.com/citations?user=mzhKxEoAAAAJ&hl=en Google Scholar] | 1 | Applied and Interdisciplinary Chemistry |
Fluoroform is weakly acidic with a pK = 25–28 and quite inert. Attempted deprotonation results in defluorination to generate and difluorocarbene (). Some organocopper and organocadmium compounds have been developed as trifluoromethylation reagents.
Fluoroform is a precursor of the Ruppert-Prakash reagent Trifluoromethyltrimethylsilane|, which is a source of the nucleophilic anion. | 1 | Applied and Interdisciplinary Chemistry |
According to some serotonin was "named for its source (sero-) and ability to modify smooth muscle tone (tonin)" an effect that may be dependent (some controversy exists) upon serotonylation.
The term serotonylation was created in 2003 by Diego J. Walther and colleagues of the Max Planck Institute for Molecular Genetics in a paper in the journal Cell. | 1 | Applied and Interdisciplinary Chemistry |
In industry, methanethiol is prepared by the reaction of hydrogen sulfide with methanol. This method is employed for the industrial synthesis of methanethiol:
:CHOH + HS → CHSH + HO
Such reactions are conducted in the presence of acidic catalysts. The other principal route to thiols involves the addition of hydrogen sulfide to alkenes. Such reactions are usually conducted in the presence of an acid catalyst or UV light. Halide displacement, using the suitable organic halide and sodium hydrogen sulfide has also been used.
Another method entails the alkylation of sodium hydrosulfide.
: RX + NaSH → RSH + NaX(X = Cl, Br, I)
This method is used for the production of thioglycolic acid from chloroacetic acid. | 0 | Theoretical and Fundamental Chemistry |
An electrostatic separator is a device for separating particles by mass in a low energy charged beam.
An example is the electrostatic precipitator used in coal-fired power plants to treat exhaust gas, removing small particles that cause air pollution.
Electrostatic separation is a process that uses electrostatic charges to separate crushed particles of material. An industrial process used to separate large amounts of material particles, electrostatic separating is most often used in the process of sorting mineral ore. This process can help remove valuable material from ore, or it can help remove foreign material to purify a substance. In mining, the process of crushing mining ore into particles for the purpose of separating minerals is called beneficiation.
Generally, electrostatic charges are used to attract or repel differently charged material. When electrostatic separation uses the force of attraction to sort particles, conducting particles stick to an oppositely charged object, such as a metal drum, thereby separating them from the particle mixture. When this type of beneficiation uses repelling force, it is normally employed to change the trajectory of falling objects to sort them into different places. This way, when a mixture of particles falls past a repelling object, the particles with the correct charge fall away from the other particles when they are repelled by the similarly charged object.
An electric charge can be positive or negative — objects with a positive charge repel other positively charged objects, thereby causing them to push away from each other, while a positively charged object would attract to a negatively charged object, thereby causing the two to draw together.
Experiments showing electrostatic sorting in action can help make the process more clear. To exhibit electrostatic separation at home, an experiment can be conducted using peanuts that are still in their shells. When the shells are rubbed off of the peanuts and gently smashed into pieces, an electrostatically charged device, like a comb rubbed quickly against a wool sweater, will pick up the peanut shells with static electricity. The lightweight crushed shells that are oppositely charged from the comb easily move away from the edible peanut parts when the comb is passed nearby.
The electrostatic separation of conductors is one method of beneficiation; another common beneficiation method is magnetic beneficiation. Electrostatic separation is a preferred sorting method when dealing with separating conductors from electrostatic separation non-conductors. In a similar way to that in which electrostatic separation sorts particles with different electrostatic charges magnetic beneficiation sorts particles that respond to a magnetic field. Electrostatic beneficiation is effective for removing particulate matter, such as ash from mined coal, while magnetic separation functions well for removing the magnetic iron ore from deposits of clay in the earth. | 0 | Theoretical and Fundamental Chemistry |
Transduction with viral vectors can be used to insert or modify genes in mammalian cells. It is often used as a tool in basic research and is actively researched as a potential means for gene therapy. | 1 | Applied and Interdisciplinary Chemistry |
Organocopper reagents are the most common nucleophiles for the β-addition step. These reagents can be generated catalytically in the presence of Grignard reagents using either copper(I) or copper(II) salts.
Copper reagents can also be used stoichiometrically, and among these, organocuprates are the most common (they are more reactive than the corresponding neutral organocopper(I) compounds). The cuprate counterion may affect the addition and subsequent enolate reaction in subtle ways. Additions involving higher-order cuprates must be quenched with a silyl halide before alkylation.
When unsymmetrical cuprates are employed, the group whose carbon-copper bond contains less s character is almost always transferred to the β-position. A few exceptions exist, however. In the example below, conducting the reaction in THF led to transfer of the vinyl moiety, while other solvents promoted methyl transfer.
Enolates can also be used as nucleophiles for vicinal difunctionalization reactions. To prevent simple Michael addition (which culminates in protonation of the enolate intermediate), trapping by the electrophile must be intramolecular.
Considerations of the electrophile should take into account the nature of the conjugate enolate generated after the first step. Relatively reactive alkylating agents should be used, especially in cases involving the addition of cuprates (enolates resulting from the addition of cuprates are often unreactive). Oxophilic electrophiles should be avoided, if C-alkylation is desired. Electrophiles should also lack hydrogens acidic enough to be deprotonated by an enolate. | 0 | Theoretical and Fundamental Chemistry |
Levorphanol is listed under the Single Convention On Narcotic Drugs 1961 and is regulated like morphine in most countries. In the U.S., it is a Schedule II Narcotic controlled substance with a DEA ACSCN of 9220 and 2013 annual aggregate manufacturing quota of 4.5 kilograms. The salts in use are the tartrate (free base conversion ratio 0.58) and hydrobromide (0.76). | 0 | Theoretical and Fundamental Chemistry |
VR has similar lethal dose levels to VX (between 10–50 mg), as well as being similar in appearance. However, due to usage of diethylamino radicals instead of diisopropylamino it is more prone to decomposition. The former are worse at sterically protecting the nitrogen atom from attacking either phosphorus or the α-carbon atom adjacent to sulfur than the latter. According to UK Defence Science and Technology Laboratory Detection Department scientists Robin M. Black and John M. Harrison, chemical stability was an important factor why of all the similarly toxic phosphorylthiocholines, ethyl N-2-diisopropylaminoethyl methylphosphonothiolate in particular (now known as VX), was weaponized in the West.
According to Russian CW developer Vil Mirzayanov, in the late 1980s a group of GosNIIOKhT chemists led by Georgiy Drozd prepared a scientific report that Substance 33 had much lower shelf life than VX. The report, writes Mirzayanov, caused panic in the institute top management and the military representative office, and later was met with administrative resistance. This finding was independently verified by another chemist Igor Revelskiy but his report wasn't approved either.
Following the poisoning of Sergei and Yulia Skripal, former head of the GosNIIOKhT security department Nikolay Volodin said in an interview to Novaya Gazeta that Substance 33 was decomposing too quickly in combat conditions, and implied that this fact may have influenced the decision to continue research on the Novichok program. | 1 | Applied and Interdisciplinary Chemistry |
Aluminum, copper, molybdenum, cobalt, mercury reserves and most importantly electricity for the smelting process has led to the development of non-ferrous metallurgy. The Zeylik mine in Daskasan district is the main provider of the alunite for aluminum production. The extracted ore here transported through Guschu-Alabashli railway to the aluminum plant located in Ganja city. The obtained aluminum oxide is brought to Sumgayit aluminum plant in order produce aluminum. Ganja Aluminum Plant produces sulfuric acid, aluminum oxide, and potassium fertilizer through extracted ore from Zalik deposit in Dashkesen. Aluminum oxide is also produced in Sumgait. AzerGold CJSC (created by the Presidential Decree No. 1047 on February 11, 2015) implements exploration, management, and also extraction, processing and sale of precious and non-ferrous metal ore deposits located within the borders of the country. In 2017, the volume of exports of precious metals carried out by this company amounted to 77340 million dollars. | 1 | Applied and Interdisciplinary Chemistry |
Constant viscosity elastic liquids, also known as Boger fluids are elastic fluids with constant viscosity. This creates an effect in the fluid where it flows like a liquid, yet behaves like an elastic solid when stretched out. Most elastic fluids exhibit shear thinning (viscosity decreases as shear strain is applied), because they are solutions containing polymers. But Boger fluids are exceptions since they are highly dilute solutions, so dilute that shear thinning caused by the polymers can be ignored. Boger fluids are made primarily by adding a small amount of polymer to a Newtonian fluid with a high viscosity, a typical solution being polyacrylamide mixed with corn syrup. It is a simple compound to synthesize but important to the study of rheology because elastic effects and shear effects can be clearly distinguished in experiments using Boger fluids. Without Boger fluids, it was difficult to determine if a non-Newtonian effect was caused by elasticity, shear thinning, or both; non-Newtonian flow caused by elasticity was rarely identifiable. Since Boger fluids can have constant viscosity, an experiment can be done where the results of the flow rates of a Boger liquid and a Newtonian liquid with the same viscosity can be compared, and the difference in the flow rates would show the change caused by the elasticity of the Boger liquid. | 1 | Applied and Interdisciplinary Chemistry |
Prokaryotic cells have various shapes; the four basic shapes of bacteria are:
* Cocci – A bacterium that is spherical or ovoid is called a coccus (Plural, cocci). e.g. Streptococcus, Staphylococcus.
* Bacilli – A bacterium with cylindrical shape called rod or a bacillus (Plural, bacilli).
* Spiral bacteria – Some rods twist into spiral shapes and are called spirilla (singular, spirillum).
* Vibrio – comma-shaped
The archaeon Haloquadratum has flat square-shaped cells. | 1 | Applied and Interdisciplinary Chemistry |
In two dimensions, parabolic LCSs are also solutions of the global shearless variational principle described above for hyperbolic LCSs. As such, parabolic LCSs are composed of shrink lines and stretch lines that represent geodesics of the Lorentzian metric tensor . In contrast to hyperbolic LCSs, however, parabolic LCSs satisfy more robust boundary conditions: they remain stationary curves of the material-line-averaged shear functional even under variations to their endpoints. This explains the high degree of robustness and observability that jet cores exhibit in mixing. This is to be contrasted with the highly sensitive and fading footprint of hyperbolic LCSs away from strongly hyperbolic regions in diffusive tracer patterns.
Under variable endpoint boundary conditions, initial positions of parabolic LCSs turn out to be alternating chains of shrink lines and stretch lines that connect singularities of these line fields. These singularities occur at points where , and hence no infinitesimal deformation takes place between the two time instances and . Fig. 14b shows an example of parabolic LCSs in Jupiter's atmosphere, located using this variational theory. The chevron-type shapes forming out of circular material blobs positioned along the jet core is characteristic of tracer deformation near parabolic LCSs. | 1 | Applied and Interdisciplinary Chemistry |
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