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Chakrabarti (1976) has identified six early iron-using centres in India: Baluchistan, the Northwest, the Indo-Gangetic divide and the upper Gangetic valley, eastern India, Malwa and Berar in central India and the megalithic south India. The central Indian region seems to be the earliest iron-using centre.
According to Tewari, iron using and iron "was prevalent in the Central Ganga Plain and the Eastern Vindhyas from the early 2nd millennium BC."
The earliest evidence for smelted iron in India dates to 1300 to 1000 BCE. These early findings also occur in places like the Deccan and the earliest evidence for smelted iron occurs in Central India, not in north-western India. Moreover, the dates for iron in India are not later than in those of Central Asia, and according to some scholars (e.g. Koshelenko 1986) the dates for smelted iron may actually be earlier in India than in Central Asia and Iran. The Iron Age did however not necessary imply a major social transformation, and Gregory Possehl wrote that "the Iron Age is more of a continuation of the past then a break with it".
Archaeological data suggests that India was "an independent and early centre of iron technology." According to Shaffer, the "nature and context of the iron objects involved [of the BRW culture] are very different from early iron objects found in Southwest Asia." In Central Asia, the development of iron technology was not necessarily connected with Indo-Iranian migrations either.
J.M. Kenoyer (1995) also remarks that there is a "long break in tin acquisition" necessary for the production of "tin bronzes" in the Indus Valley region, suggesting a lack of contact with Baluchistan and northern Afghanistan, or the lack of migrants from the north-west who could have procured tin. | 1 | Applied and Interdisciplinary Chemistry |
Affinity purification of albumin and macroglobulin contamination is helpful in removing excess albumin and α-macroglobulin contamination, when performing mass spectrometry. In affinity purification of serum albumin, the stationary used for collecting or attracting serum proteins can be Cibacron Blue-Sepharose. Then the serum proteins can be eluted from the adsorbent with a buffer containing thiocyanate (SCN). | 0 | Theoretical and Fundamental Chemistry |
The scope of organometallic reagents that may be aminated by electrophilic methods is large. Alkyl Grignard reagents, alkylithium compounds, alkylzinc compounds, and alkylcuprates have been aminated with electrophilic reagents successfully. Among sp-centered carbanions, vinyllithium compounds, vinylcuprates, and vinyl Grignard reagents react with electrophilic aminating reagents to afford enamines.
Aryl and heteroaryl organolithium reagents undergo efficient electrophilic amination under copper (I) catalyzed condition mediated by recoverable silicon reagents, termed siloxane transfer agents.
The scope of sp-centered carbanions is limited to alkynylcuprates. Enolates and silyl enol ethers, the most widely used class of carbon nucleophiles in electrophilic amination reactions, participate in amination, adization and hydrazination reactions.
The primary application of alkylmetal reagents in electrophilic amination reactions is the synthesis of hindered amines, many of which are difficult to prepare through nucleophilic displacement with an alkyl halide (nucleophilic amination). For instance, in the presence of a copper(II) catalyst, bulky organozinc reagents react with O-acylhydroxylamines to afford hindered amines.
Allylic metal species can be used to prepare allylic amines through electrophilic amination. Although allylic amines are usually prepared through nucleophilic amination of allylic halides, a few examples of electrophlic amination of allylic substrates are known. In the example below, an allylic zirconium reagent (obtained by hydrozirconation) is trapped with an O-alkylhydroxylamine.
The electrophilic amination of enolates yields α-amino carbonyl compounds. When chiral oxazolidinones are used in conjunction with azo compounds, enantioselectivity is observed (see above). BINAP can also be used for this purpose in the amination of silyl enol ethers.
Aryl and heteroaryl organometallic reagents undergo many of the same transformations as their aliphatic counterparts. Formation of amines, hydrazines, and azides is possible through the use of various electrophilic aminating reagents. An example employing a nitrenoid reagent is shown below.
Intramolecular amination is possible, and has been used to prepare small and medium rings. In the example below, deprotonation of an activated methylene compound containing an O-phosphinoylhydroxylamine led to the cyclic amine shown. | 0 | Theoretical and Fundamental Chemistry |
Generation I covers the commercially available mechanical systems associated with the fluid handling components. Generation I has adopted the ANSI/ISA SP76.00.2002 miniature, modular mechanical standard. This standard precisely defines inlet and outlet ports and overall dimensions which allow Lego-like interchangeability of components, between different manufacturers. The ANSI/ISA standard is referenced by the International Electrotechnical Commission in publication IEC 62339-1:2006.
Currently three manufacturers produce the mechanical mounting system (known as a substrate) which serves as the platform for attaching various components. Since the components are bolted to the surface of the substrate, sealed by O-rings, they are sometimes referred to as surface mount devices. (The semiconductor industry has a related system; however, the sealing is done by metallic seals rather than elastomeric O-rings.) There are currently over 60 different types of surface mount components available from various suppliers who provide valves, filters and regulators as well as pressure and flow sensing devices. Although the platform for mounting various components is common among the manufacturers, the interconnections below the surface are proprietary. The following figure shows three of the common designs. (From left to right) A Swagelok system which uses various lengths of tube connectors set in rigid channels; a CIRCORTech design which uses a single block with assorted flow-tubes; and a Parker Hannifin design which uses various blocks ported together with small connectors which also serve as flow paths. | 1 | Applied and Interdisciplinary Chemistry |
Insertions are another common type of carbene reaction, a form of oxidative addition. Insertions may or may not occur in single step (see above). The end result is that the carbene interposes itself into an existing bond, preferably X–H (X not carbon), else C–H or (failing that) a C–C bond. Alkyl carbenes insert much more selectively than methylene, which does not differentiate between primary, secondary, and tertiary C-H bonds.
The 1,2-rearrangement produced from intramolecular insertion into a bond adjacent to the carbene center is a nuisance in some reaction schemes, as it consumes the carbene to yield the same effect as a traditional elimination reaction. Generally, rigid structures favor intramolecular insertions. In flexible structures, five-membered ring formation is preferred to six-membered ring formation. When such insertions are possible, no intermolecular insertions are seen. Both inter- and intra-molecular insertions admit asymmetric induction from a chiral metal catalyst. | 0 | Theoretical and Fundamental Chemistry |
The first gamma ray source to be discovered was the radioactive decay process called gamma decay. In this type of decay, an excited nucleus emits a gamma ray almost immediately upon formation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium. Villard knew that his described radiation was more powerful than previously described types of rays from radium, which included beta rays, first noted as "radioactivity" by Henri Becquerel in 1896, and alpha rays, discovered as a less penetrating form of radiation by Rutherford, in 1899. However, Villard did not consider naming them as a different fundamental type. Later, in 1903, Villards radiation was recognized as being of a type fundamentally different from previously named rays by Ernest Rutherford, who named Villards rays "gamma rays" by analogy with the beta and alpha rays that Rutherford had differentiated in 1899. The "rays" emitted by radioactive elements were named in order of their power to penetrate various materials, using the first three letters of the Greek alphabet: alpha rays as the least penetrating, followed by beta rays, followed by gamma rays as the most penetrating. Rutherford also noted that gamma rays were not deflected (or at least, not deflected) by a magnetic field, another property making them unlike alpha and beta rays.
Gamma rays were first thought to be particles with mass, like alpha and beta rays. Rutherford initially believed that they might be extremely fast beta particles, but their failure to be deflected by a magnetic field indicated that they had no charge. In 1914, gamma rays were observed to be reflected from crystal surfaces, proving that they were electromagnetic radiation. Rutherford and his co-worker Edward Andrade measured the wavelengths of gamma rays from radium, and found they were similar to X-rays, but with shorter wavelengths and thus, higher frequency. This was eventually recognized as giving them more energy per photon, as soon as the latter term became generally accepted. A gamma decay was then understood to usually emit a gamma photon. | 0 | Theoretical and Fundamental Chemistry |
Poiseuille's law on blood circulation in the body is dependent on laminar flow. In turbulent flow the flow rate is proportional to the square root of the pressure gradient, as opposed to its direct proportionality to pressure gradient in laminar flow.
Using the definition of the Reynolds number we can see that a large diameter with rapid flow, where the density of the blood is high, tends towards turbulence. Rapid changes in vessel diameter may lead to turbulent flow, for instance when a narrower vessel widens to a larger one. Furthermore, a bulge of atheroma may be the cause of turbulent flow, where audible turbulence may be detected with a stethoscope. | 1 | Applied and Interdisciplinary Chemistry |
Analysis of metabolic networks of proteins hearkens back to the 1940s, but it was not until the late 1990s and early 2000s that computational data-driven genomic analyses to predict functional context and networks of genetic associations appeared in earnest. Since then, the interactomes of many model organisms are considered to have been well characterized, notably the Saccharomyces cerevisiae Interactome and the Drosophila interactome.
High throughput experimental approaches for discovering protein–protein interactions typically perform a version of the two-hybrid screening approach or tandem affinity purification followed by mass spectrometry. Information from experiments and literature curation are compiled into databases of protein interactions, such as DIP, and BioGRID. A more recent effort, HINT-KB, attempts to amalgamate most of the current PPI databases, but filtering systematically erroneous interactions as well as trying to correct for inherent sociological sampling biases in literature curated datasets.
Smaller human interactome networks have been described in the specific context of important drivers of many different disorders, including neurodegenerative disorders, autism and other psychiatric disorders, and cancer. Cancer gene networks have been particularly well studied, due in part to large genome initiatives such as The Cancer Genome Atlas (TCGA). A large portion of the mutational landscape including intra-tumoural heterogeneity has been mapped for most common types of cancers (for example, breast cancer has been well studied), and many studies have also investigated the difference between active driver genes and passive passenger mutations in the context of cancer interaction networks.
The first attempts at large-scale integrative human interactome mapping occurred around 2005. Stetzl et al. used a protein matrix of 4500 baits and 5600 preys in a yeast two hybrid system to piece together the interactome, and Rual et al. performed a similar yeast-two hybrid study verified with co-affinity purification and correlation with other biological attributes, revealing more than 300 connections to 100 disease-associated proteins. Since those pioneering efforts, hundreds of similar studies have been conducted. Compiled databases such as UniHI provide platform for single entry. Futschik et al. performed a meta analysis of eight interactome maps and found that of 57 000 interacting proteins in total, there was a small (albeit statistically significant) overlap between the different databases, indicating considerable selection and detection biases.
In 2010, around 130 000 binary interactions in the interactome were described in the most popular databases, but many were verified with only one source. With the rapid development of high throughput methods, datasets still suffer from high rates of false positives and low coverage of the interactome. Tyagi et al. described a novel framework for incorporating structural complexes and binding interfaces for verification. This was part of much larger efforts for PPI verification; interaction networks are typically validated further by using a combination of coexpression profiles, protein structural information, Gene ontology terms, topological considerations, and colocalization before being considered “high-confidence”.
A recent resource paper (November 2014) attempts to provide a more comprehensive proteome level map of the human interactome. It found vast uncharted territory in the human interactome, and used diverse methods to build a new interactome map correcting for curation bias, including probing all pairwise combinations of 13 000 protein products for interaction using Yeast two hybrid and co-affinity purification, in a massive coordinated effort across research labs in Canada and the United States. However, this still represents confirmation of but a fraction of expected interactions – around 30 000 of high confidence. Despite the coordinated efforts of many, the human interactome is still very much a work in progress. | 1 | Applied and Interdisciplinary Chemistry |
In order to enhance DNA-RNA affinity, enzyme processivity, and thermostability, five amino acid substitutions were incorporated into the M-MLV reverse transcriptase. The mutant M-MLV RT was then incorporated into PE1 to give rise to (Cas9 (H840A)-M-MLV RT(D200N/L603W/T330P/T306K/W313F)). Efficiency improvement was observed over PE1. | 1 | Applied and Interdisciplinary Chemistry |
The microbial loop describes a trophic pathway in the marine microbial food web where dissolved organic carbon (DOC) is returned to higher trophic levels via its incorporation into bacterial biomass, and then coupled with the classic food chain formed by phytoplankton-zooplankton-nekton. The term microbial loop was coined by Farooq Azam, Tom Fenchel et al. in 1983 to include the role played by bacteria in the carbon and nutrient cycles of the marine environment. In general, dissolved organic carbon is introduced into the ocean environment from bacterial lysis, the leakage or exudation of fixed carbon from phytoplankton (e.g., mucilaginous exopolymer from diatoms), sudden cell senescence, sloppy feeding by zooplankton, the excretion of waste products by aquatic animals, or the breakdown or dissolution of organic particles from terrestrial plants and soils. Bacteria in the microbial loop decompose this particulate detritus to utilize this energy-rich matter for growth. Since more than 95% of organic matter in marine ecosystems consists of polymeric, high molecular weight (HMW) compounds (e.g., protein, polysaccharides, lipids), only a small portion of total dissolved organic matter (DOM) is readily utilizable to most marine organisms at higher trophic levels. This means that dissolved organic carbon is not available directly to most marine organisms; marine bacteria introduce this organic carbon into the food web, resulting in additional energy becoming available to higher trophic levels. | 0 | Theoretical and Fundamental Chemistry |
In biochemistry, chemosynthesis is the biological conversion of one or more carbon-containing molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic compounds (e.g., hydrogen gas, hydrogen sulfide) or ferrous ions as a source of energy, rather than sunlight, as in photosynthesis. Chemoautotrophs, organisms that obtain carbon from carbon dioxide through chemosynthesis, are phylogenetically diverse. Groups that include conspicuous or biogeochemically important taxa include the sulfur-oxidizing Gammaproteobacteria, the Campylobacterota, the Aquificota, the methanogenic archaea, and the neutrophilic iron-oxidizing bacteria.
Many microorganisms in dark regions of the oceans use chemosynthesis to produce biomass from single-carbon molecules. Two categories can be distinguished. In the rare sites where hydrogen molecules (H) are available, the energy available from the reaction between CO and H (leading to production of methane, CH) can be large enough to drive the production of biomass. Alternatively, in most oceanic environments, energy for chemosynthesis derives from reactions in which substances such as hydrogen sulfide or ammonia are oxidized. This may occur with or without the presence of oxygen.
Many chemosynthetic microorganisms are consumed by other organisms in the ocean, and symbiotic associations between chemosynthesizers and respiring heterotrophs are quite common. Large populations of animals can be supported by chemosynthetic secondary production at hydrothermal vents, methane clathrates, cold seeps, whale falls, and isolated cave water.
It has been hypothesized that anaerobic chemosynthesis may support life below the surface of Mars, Jupiter's moon Europa, and other planets. Chemosynthesis may have also been the first type of metabolism that evolved on Earth, leading the way for cellular respiration and photosynthesis to develop later. | 1 | Applied and Interdisciplinary Chemistry |
The binding process is reversible, indicating that the associate constant (k) is not far larger than disassociate constant (k). Combing the rate of the reaction, k, k, concentration, and time, the relation of the free guest molecule and time can be calculated. By calculating the integration of UV spectrum or NMR, the concentration as a function of time curve can be obtained. | 0 | Theoretical and Fundamental Chemistry |
Carcass weight predicts what an animal's total retail product will be compared to other animals of that breed. It does not however predict percent retail value, or the actual amount of sellable meat that can be produced from the carcass.
Fat thickness determined the expected external and seam fat the animal will contain. These two factors contribute to the greatest waste in an animal and best way to reduce economic loss. Fat thickness EPDs can help producers reduce this loss, by using animals with mid range EPDs, so as not to have too little or too much fat.
Marbling EPDs are also important in the beef industry for predicting palatability in a beef carcass. They show the estimated USDA Quality grading System and marbling score an animal would receive if it were slaughtered. This EDP is different in that it is measured in units of marbling score, and not in weight gained by an animal. Higher values indicate the presence of genes that will produce more intramuscular fat. | 1 | Applied and Interdisciplinary Chemistry |
The methanol economy is a suggested future economy in which methanol and dimethyl ether replace fossil fuels as a means of energy storage, ground transportation fuel, and raw material for synthetic hydrocarbons and their products. It offers an alternative to the proposed hydrogen economy or ethanol economy, although these concepts are not exclusive. Methanol can be produced from a variety of sources including fossil fuels (natural gas, coal, oil shale, tar sands, etc.) as well as agricultural products and municipal waste, wood and varied biomass. It can also be made from chemical recycling of carbon dioxide.
Nobel prize laureate George A. Olah advocated a methanol economy. | 1 | Applied and Interdisciplinary Chemistry |
Many experimenters tried to immobilize the electrolyte of an electrochemical cell to make it more convenient to use. The Zamboni pile of 1812 is a high-voltage dry battery but capable of delivering only minute currents. Various experiments were made with cellulose, sawdust, spun glass, asbestos fibers, and gelatine.
In 1886, Carl Gassner obtained a German patent (No. 37,758) on a variant of the (wet) Leclanché cell, which came to be known as the dry cell because it did not have a free liquid electrolyte. Instead, the ammonium chloride was mixed with Plaster of Paris to create a paste, with a small amount of zinc chloride added in to extend the shelf life. The manganese dioxide cathode was dipped in this paste, and both were sealed in a zinc shell, which also acts as the anode. In November 1887, he obtained for the same device. A dry-battery was invented in Japan during the Meiji Era in 1887. The inventor was Sakizō Yai. However, Yai didn't have enough money to file the patent, the first patent holder of a battery in Japan was not Yai, but Takahashi Ichisaburo. Wilhelm Hellesen also invented a dry-battery in 1887 and obtained in 1890.
Unlike previous wet cells, Gassners dry cell is more solid, does not require maintenance, does not spill, and can be used in any orientation. It provides a potential of 1.5 volts. The first mass-produced model was the Columbia dry cell, first marketed by the National Carbon Company in 1896. The NCC improved Gassners model by replacing the plaster of Paris with coiled cardboard, an innovation that leaves more space for the cathode and makes the battery easier to assemble. It was the first convenient battery for the masses and made portable electrical devices practical. Gasner is a German scientist.
The zinc–carbon cell (as it came to be known) is still manufactured today. | 0 | Theoretical and Fundamental Chemistry |
Functional elements in intergenic regions will evolve slowly because their sequence is maintained by negative selection. In species with very large genomes, a large percentage of intergenic regions is probably junk DNA and it will evolve at the neutral rate of evolution. Junk DNA sequences are not maintained by purifying selection but gain-of-function mutations with deleterious fitness effects can occur.
Phylostratigraphic inference and bioinformatics methods have shown that intergenic regions can—on geological timescales—transiently evolve into open reading frame sequences that mimic those of protein coding genes, and can therefore lead to the evolution of novel protein-coding genes in a process known as de novo gene birth. | 1 | Applied and Interdisciplinary Chemistry |
Microalgae do not settle by gravity, therefore expensive harvesting techniques must be applied. This is a major bottleneck of microalgal technology. Bioflocculation of microalgae and bacteria addresses this.
MaB-flocs or Microalgal Bacterial flocs settle by gravity, up to density of 20 g per liter. This is a major improvement for microalgal technology for wastewater treatment.
Currently, MaB-flocs are being applied for sewage treatment on lab and pilot scale in Germany, New Zealand and Belgium. The idea is to scavenge nutrients such as nitrogen and phosphorus from the wastewater, sometimes combined with flue gas treatment.
Nutritional evaluation of such microbial protein or single cell protein as an unconventional protein feedstuff or ingredient in artificial animal feeds have gained much importance lately. Its nutritional strengths and bottlenecks are much described lately. | 1 | Applied and Interdisciplinary Chemistry |
Attenuators may be classified according to the type of molecule which induces the change in RNA structure. It is likely that transcription-attenuation mechanisms developed early, perhaps prior to the archaea/bacteria separation and have since evolved to use a number of different sensing molecules (the tryptophan biosynthetic operon has been found to use three different mechanisms in different organisms.) | 1 | Applied and Interdisciplinary Chemistry |
OpenFOAM (Open Field Operation And Manipulation) is a C++ toolbox for the development of customized numerical solvers, and pre-/post-processing utilities for the solution of continuum mechanics problems, most prominently including computational fluid dynamics (CFD).
The OpenFOAM software is used in research organisations, academic institutes and across many types of industries, for example, automotive, manufacturing, process engineering and environmental engineering.
OpenFOAM is open-source software which is freely available and licensed under the GNU General Public License Version 3, with the following variants:
# OpenFOAM, released by OpenCFD Ltd. (with the name trademarked since 2007) first released as open-source in 2004. (Note: since 2012, OpenCFD Ltd is wholly-owned subsidiary of ESI Group)
# FOAM-Extend, released by Wikki Ltd. (since 2009)
# OpenFOAM, released by OpenFOAM Foundation. (since 2011) | 1 | Applied and Interdisciplinary Chemistry |
One cannot assume that under all conditions the yield of strange quarks is in thermal equilibrium. In general, the quark-flavor composition of the plasma varies during its ultra short lifetime as new flavors of quarks such as strangeness are cooked up inside. The up and down quarks from which normal matter is made are easily produced as quark–antiquark pairs in the hot fireball because they have small masses. On the other hand, the next lightest quark flavor—strange quarks—will reach its high quark–gluon plasma thermal abundance provided that there is enough time and that the temperature is high enough. This work elaborated the kinetic theory of strangness production proposed by T. Biro and J. Zimanyi who demonstrated that strange quarks could not be produced fast enough alone by quark-antiquark reactions. A new mechanism operational alone in QGP was proposed. | 0 | Theoretical and Fundamental Chemistry |
One of the aims of the Chemical Society was to hold meetings for "the communication and discussion of discoveries and observations, an account of which shall be published by the Society". In 1847, its importance was recognised by a Royal Charter, which added to its role in the advancement of science, the development of chemical applications in industry. Its members included eminent chemists from overseas including August Wilhelm von Hofmann, who became its president in 1861. Membership was open to all those interested in chemistry, but fellowship was for long restricted to men.
In 1904, Edith Humphrey, thought to be the first British woman to gain a doctorate in chemistry (at the University of Zurich), was one of nineteen women chemists to petition the Chemical Society for admission of women to fellowship. This was eventually granted in 1919, and Humphrey was subsequently elected to fellowship.
The Chemical Society of London succeeded where a number of previous chemical associations - the Lunar Society's London branch chemical society of the 1780s, the Animal Chemical Club of 1805, the London Chemical Society of 1824 - failed. One assertion of a cause of success of the Chemical Society of London is that it was, unlike its forerunners, a "fruitful amalgamation of the technological and academic chemist".
Its activities expanded over the years, including eventually becoming a major publisher in the field of chemistry. On 15 May 1980, it amalgamated with the Royal Institute of Chemistry, the Faraday Society and the Society for Analytical Chemistry to become the Royal Society of Chemistry. | 1 | Applied and Interdisciplinary Chemistry |
* Cyclopentadecanone (musk-ketone)
* Dihydrojasmone (fruity woody floral)
* Oct-1-en-3-one (blood, metallic, mushroom-like)
* 2-Acetyl-1-pyrroline (fresh bread, jasmine rice)
* 6-Acetyl-2,3,4,5-tetrahydropyridine (fresh bread, tortillas, popcorn) | 0 | Theoretical and Fundamental Chemistry |
Passive daytime radiative cooling surfaces can be installed over the surface of a body of water for cooling. In a controlled study, a body of water was cooled 10.6ᵒC below the ambient temperature with the usage of a photonic radiator.
PDRC surfaces have been developed to cool ice and prevent ice from melting under sunlight. It has been proposed as a sustainable method for ice protection. This can be applied to protect iced or refrigerated food from spoiling. | 0 | Theoretical and Fundamental Chemistry |
The strength of a synapse has been defined by Bernard Katz as the product of (presynaptic) release probability pr, quantal size q (the postsynaptic response to the release of a single neurotransmitter vesicle, a quantum), and n, the number of release sites. "Unitary connection" usually refers to an unknown number of individual synapses connecting a presynaptic neuron to a postsynaptic neuron.
The amplitude of postsynaptic potentials (PSPs) can be as low as 0.4 mV to as high as 20 mV. The amplitude of a PSP can be modulated by neuromodulators or can change as a result of previous activity. Changes in the synaptic strength can be short-term, lasting seconds to minutes, or long-term (long-term potentiation, or LTP), lasting hours. Learning and memory are believed to result from long-term changes in synaptic strength, via a mechanism known as synaptic plasticity. | 1 | Applied and Interdisciplinary Chemistry |
* Isotope analysis is the determination of isotopic signature, the relative abundances of isotopes of a given element in a particular sample. Isotope analysis is frequently done by isotope ratio mass spectrometry. For biogenic substances in particular, significant variations of isotopes of C, N, and O can occur. Analysis of such variations has a wide range of applications, such as the detection of adulteration in food products or the geographic origins of products using isoscapes. The identification of certain meteorites as having originated on Mars is based in part upon the isotopic signature of trace gases contained in them.
* Isotopic substitution can be used to determine the mechanism of a chemical reaction via the kinetic isotope effect.
* Another common application is isotopic labeling, the use of unusual isotopes as tracers or markers in chemical reactions. Normally, atoms of a given element are indistinguishable from each other. However, by using isotopes of different masses, even different nonradioactive stable isotopes can be distinguished by mass spectrometry or infrared spectroscopy. For example, in stable isotope labeling with amino acids in cell culture (SILAC) stable isotopes are used to quantify proteins. If radioactive isotopes are used, they can be detected by the radiation they emit (this is called radioisotopic labeling).
* Isotopes are commonly used to determine the concentration of various elements or substances using the isotope dilution method, whereby known amounts of isotopically substituted compounds are mixed with the samples and the isotopic signatures of the resulting mixtures are determined with mass spectrometry. | 0 | Theoretical and Fundamental Chemistry |
Neurotrophin binding to p75NTR activates the c-Jun N-terminal kinases (JNK) signaling pathway causing apoptosis of developing neurons. JNK, through a series of intermediates, activates p53 and p53 activates Bax which initiates apoptosis. TrkA can prevent p75NTR-mediated JNK pathway apoptosis. | 1 | Applied and Interdisciplinary Chemistry |
One proposed mechanism for Müllerian mimicry is the "two step hypothesis". This states that a large mutational leap initially establishes an approximate resemblance of the mimic to the model, both species already being aposematic. In a second step, smaller changes establish a closer resemblance. This is only likely to work, however, when a trait is governed by a single gene, and many coloration patterns are certainly controlled by multiple genes. | 1 | Applied and Interdisciplinary Chemistry |
The reaction of carbon disulfide (CS) with electron deficient acetylene derivatives is proposed to give transient 1,3-dithiolium carbenes (i.e. where X = X = S), which then dimerise to give derivatives of tetrathiafulvene. Thus it is possible that the reverse of this process might be occurring in similar carbenes. | 0 | Theoretical and Fundamental Chemistry |
This approach relies on observation and experimental data. It is specifically tailored to the geometrical shape of the vortex tube and the details of its flow and is designed to match the particular observables of the complex vortex tube flow, namely turbulence, acoustic phenomena, pressure fields, air velocities and many others. The earlier published models of the vortex tube are phenomenological. They are:
# Radial pressure difference: centrifugal compression and air expansion
# Radial transfer of angular momentum
# Radial acoustic streaming of energy
# Radial heat pumping
More on these models can be found in recent review articles on vortex tubes.
The phenomenological models were developed at an earlier time when the turbine equation of Euler was not thoroughly analyzed; in the engineering literature, this equation is studied mostly to show the work output of a turbine; while temperature analysis is not performed since turbine cooling has more limited application unlike power generation, which is the main application of turbines. Phenomenological studies of the vortex tube in the past have been useful in presenting empirical data. However, due to the complexity of the vortex flow this empirical approach was able to show only aspects of the effect but was unable to explain its operating principle. Dedicated to empirical details, for a long time the empirical studies made the vortex tube effect appear enigmatic and its explanation – a matter of debate. | 0 | Theoretical and Fundamental Chemistry |
The basic components needed for the exploding wire method are a thin conductive wire and a capacitor. The wire is typically gold, aluminum, iron or platinum, and is usually less than 0.5 mm in diameter. The capacitor has an energy consumption of about 25 kWh/kg and discharges a pulse of current density 10 - 10 A/mm, leading to temperatures up to 100,000 K. The phenomenon occurs over a time period of only 10 - 10 seconds.
The process is as follows:
# A rising current, supplied by the capacitor, is carried across the wire.
# The current heats up the wire through ohmic heating until the metal begins to melt. The metal melts to form a broken series of imperfect spheres called unduloids. The current rises so fast that the liquid metal has no time to move out of the way.
# The unduloids vaporize. The metal vapor creates a lower resistance path, allowing an even higher current to flow.
# An electric arc is formed, which turns the vapor into plasma. A bright flash of light is also produced.
# The plasma is allowed to expand freely, creating a shock wave.
# Electromagnetic radiation is released in tandem with the shock wave.
# The shock wave pushes liquid, gaseous and plasmatic metal outwards, breaking the circuit and ending the process. | 0 | Theoretical and Fundamental Chemistry |
Brkić shows one approximation of the Colebrook equation based on the Lambert W-function
The equation was found to match the Colebrook–White equation within 3.15%. | 1 | Applied and Interdisciplinary Chemistry |
It has been suggested that the size of an organism's interactome correlates better than genome size with the biological complexity of the organism. Although protein–protein interaction maps containing several thousand binary interactions are now available for several species, none of them is presently complete and the size of interactomes is still a matter of debate. | 1 | Applied and Interdisciplinary Chemistry |
The ABO blood group system is determined by what type of glycosyltransferases are expressed in the body.
The ABO gene locus expressing the glycosyltransferases has three main allelic forms: A, B, and O. The A allele encodes 1-3-N-acetylgalactosaminyltransferase that bonds α-N-acetylgalactosamine to D-galactose end of H antigen, producing the A antigen. The B allele encodes 1-3-galactosyltransferase that joins α-D-galactose bonded to D-galactose end of H antigen, creating the B antigen. In case of O allele the exon 6 contains a deletion that results in a loss of enzymatic activity. The O allele differs slightly from the A allele by deletion of a single nucleotide - Guanine at position 261. The deletion causes a frameshift and results in translation of an almost entirely different protein that lacks enzymatic activity. This results in H antigen remaining unchanged in case of O groups.
The combination of glycosyltransferases by both alleles present in each person determines whether there is an AB, A, B or O blood type. | 0 | Theoretical and Fundamental Chemistry |
The G protein-coupled receptors have seven hydrophobic transmembrane domains. Most of them are monomeric proteins, although GABA receptors require heterodimerization to function properly. The protein's N terminus is located on the extracellular side of the membrane and its C terminus is on the intracellular side.
The 7 transmembrane spanning domains, with an external amino terminus, are often claimed as being alpha helix shaped, and the polypeptide chain is said to be composed of around 450–550 amino acids. | 1 | Applied and Interdisciplinary Chemistry |
The acidity of tellurols can be inferred by the acidity and dissociation constant of hydrogen telluride, , which has a (first) pK of 2.64 corresponding to a dissociation constant of 2.3 × 10. has a lower pK and higher dissociation constant than and . The pKa is 9.3 for vs 10.8 for .
The absence of hydrogen-bonding explains the low boiling temperature of tellurols. | 0 | Theoretical and Fundamental Chemistry |
The NPIS operates a 24-hour telephone advice service and internet database TOXBASE ([http://www.toxbase.org www.toxbase.org] for registered healthcare departments only). TOXBASE is free for UK NHS departments, and available by subscription to departments outside the UK NHS. The TOXBASE app is also available for Apple and Android devices. The app is free for individual NHS users.
The TOXBASE database contains information on approximately 17,000 products, together with generic advice on the management of poisoning. In excess of 1.5 million product accesses are made to the database each year. Most of the accesses are made by A&E staff.
NHS 111, NHS 24 and NHS Direct all use the TOXBASE database. In the UK poisons information can also be found in the British National Formulary. | 1 | Applied and Interdisciplinary Chemistry |
A variety of parameters are considered when designing and conducting RNA-Seq experiments:
* Tissue specificity: Gene expression varies within and between tissues, and RNA-Seq measures this mix of cell types. This may make it difficult to isolate the biological mechanism of interest. Single cell sequencing can be used to study each cell individually, mitigating this issue.
* Time dependence: Gene expression changes over time, and RNA-Seq only takes a snapshot. Time course experiments can be performed to observe changes in the transcriptome.
* Coverage (also known as depth): RNA harbors the same mutations observed in DNA, and detection requires deeper coverage. With high enough coverage, RNA-Seq can be used to estimate the expression of each allele. This may provide insight into phenomena such as imprinting or cis-regulatory effects. The depth of sequencing required for specific applications can be extrapolated from a pilot experiment.
* Data generation artifacts (also known as technical variance): The reagents (e.g., library preparation kit), personnel involved, and type of sequencer (e.g., Illumina, Pacific Biosciences) can result in technical artifacts that might be mis-interpreted as meaningful results. As with any scientific experiment, it is prudent to conduct RNA-Seq in a well controlled setting. If this is not possible or the study is a meta-analysis, another solution is to detect technical artifacts by inferring latent variables (typically principal component analysis or factor analysis) and subsequently correcting for these variables.
* Data management: A single RNA-Seq experiment in humans is usually 1-5 Gb (compressed), or more when including intermediate files. This large volume of data can pose storage issues. One solution is compressing the data using multi-purpose computational schemas (e.g., gzip) or genomics-specific schemas. The latter can be based on reference sequences or de novo. Another solution is to perform microarray experiments, which may be sufficient for hypothesis-driven work or replication studies (as opposed to exploratory research). | 1 | Applied and Interdisciplinary Chemistry |
He left the semiconductor industry in 1972, and began a new career as an entrepreneur in data security and cryptography. In 1972, he founded Atalla Technovation, later called Atalla Corporation, which dealt with safety problems of banking and financial institutions. | 0 | Theoretical and Fundamental Chemistry |
An element of a flowing liquid or gas will endure forces from the surrounding fluid, including viscous stress forces that cause it to gradually deform over time. These forces can be mathematically first order approximated by a viscous stress tensor, usually denoted by .
The deformation of a fluid element, relative to some previous state, can be first order approximated by a strain tensor that changes with time. The time derivative of that tensor is the strain rate tensor, that expresses how the element's deformation is changing with time; and is also the gradient of the velocity vector field at that point, often denoted .
The tensors and can be expressed by 3×3 matrices, relative to any chosen coordinate system. The fluid is said to be Newtonian if these matrices are related by the equation
where is a fixed 3×3×3×3 fourth order tensor that does not depend on the velocity or stress state of the fluid. | 1 | Applied and Interdisciplinary Chemistry |
A static mixer is a device for the continuous mixing of fluid materials, without moving components. Normally the fluids to be mixed are liquid, but static mixers can also be used to mix gas streams, disperse gas into liquid or blend immiscible liquids. The energy needed for mixing comes from a loss in pressure as fluids flow through the static mixer. One design of static mixer is the plate-type mixer and another common device type consists of mixer elements contained in a cylindrical (tube) or squared housing. Mixer size can vary from about 6 mm to 6 meters diameter. Typical construction materials for static mixer components include stainless steel, polypropylene, Teflon, PVDF, PVC, CPVC and polyacetal. The latest designs involve static mixing elements made of glass-lined steel. | 1 | Applied and Interdisciplinary Chemistry |
The total synthesis of several brevianamides have been reported, for brevianamide-B and for brevianamide-E. | 0 | Theoretical and Fundamental Chemistry |
Radiation pressure is the force that electromagnetic radiation exerts on matter. In 1873 Maxwell published his treatise on electromagnetism in which he predicted radiation pressure. The force was experimentally demonstrated for the first time by Lebedev and reported at a conference in Paris in 1900, and later published in more detail in 1901. Following Lebedev's measurements Nichols and Hull also demonstrated the force of radiation pressure in 1901, with a refined measurement reported in 1903.
In 1933, Otto Frisch deflected an atomic beam of sodium atoms with light.
This was the first realization of radiation pressure acting on a resonant absorber. | 0 | Theoretical and Fundamental Chemistry |
Ecological engineering emerged as a new idea in the early 1960s, but its definition has taken several decades to refine. Its implementation is still undergoing adjustment, and its broader recognition as a new paradigm is relatively recent. Ecological engineering was introduced by Howard Odum and others as utilizing natural energy sources as the predominant input to manipulate and control environmental systems. The origins of ecological engineering are in Odum's work with ecological modeling and ecosystem simulation to capture holistic macro-patterns of energy and material flows affecting the efficient use of resources.
Mitsch and Jorgensen summarized five basic concepts that differentiate ecological engineering from other approaches to addressing problems to benefit society and nature: 1) it is based on the self-designing capacity of ecosystems; 2) it can be the field (or acid) test of ecological theories; 3) it relies on system approaches; 4) it conserves non-renewable energy sources; and 5) it supports ecosystem and biological conservation.
Mitsch and Jorgensen were the first to define ecological engineering as designing societal services such that they benefit society and nature, and later noted the design should be systems based, sustainable, and integrate society with its natural environment.
Bergen et al. defined ecological engineering as: 1) utilizing ecological science and theory; 2) applying to all types of ecosystems; 3) adapting engineering design methods; and 4) acknowledging a guiding value system.
Barrett (1999) offers a more literal definition of the term: "the design, construction, operation and management (that is, engineering) of landscape/aquatic structures and associated plant and animal communities (that is, ecosystems) to benefit humanity and, often, nature." Barrett continues: "other terms with equivalent or similar meanings include ecotechnology and two terms most often used in the erosion control field: soil bioengineering and biotechnical engineering. However, ecological engineering should not be confused with biotechnology when describing genetic engineering at the cellular level, or bioengineering meaning construction of artificial body parts."
The applications in ecological engineering can be classified into 3 spatial scales: 1) mesocosms (~0.1 to hundreds of meters); 2) ecosystems (~one to tens of km); and 3) regional systems (>tens of km). The complexity of the design likely increases with the spatial scale. Applications are increasing in breadth and depth, and likely impacting the field's definition, as more opportunities to design and use ecosystems as interfaces between society and nature are explored. Implementation of ecological engineering has focused on the creation or restoration of ecosystems, from degraded wetlands to multi-celled tubs and greenhouses that integrate microbial, fish, and plant services to process human wastewater into products such as fertilizers, flowers, and drinking water. Applications of ecological engineering in cities have emerged from collaboration with other fields such as landscape architecture, urban planning, and urban horticulture, to address human health and biodiversity, as targeted by the UN Sustainable Development Goals, with holistic projects such as stormwater management. Applications of ecological engineering in rural landscapes have included wetland treatment and community reforestation through traditional ecological knowledge. Permaculture is an example of broader applications that have emerged as distinct disciplines from ecological engineering, where David Holmgren cites the influence of Howard Odum in development of permaculture. | 1 | Applied and Interdisciplinary Chemistry |
Prerequisite equipments for sand rammer may vary from case to case basis or testing scenario:<br />
Case 1: If the prepared sand is ready
* Tube filler accessory to fill sample tube with sand. Advantage is it lets the sand fill in from fixed distance and riddles it before filling.
<br />
Case 2: Experiment by preparing new sand sample
If sand needs to be prepared before making specimen following equipments may be needed
* Laboratory sand muller or laboratory sand mixer (for core sands)
<br />
Case 3: For low compressive strength sands and mixtures:
* Split specimen tube | 1 | Applied and Interdisciplinary Chemistry |
The dose that would be lethal to 50% of a population is a common parameter used to compare the effects of various fallout types or circumstances. Usually, the term is defined for a specific time, and limited to studies of acute lethality. The common time periods used are 30 days or less for most small laboratory animals and to 60 days for large animals and humans. The LD figure assumes that the individuals did not receive other injuries or medical treatment.
In the 1950s, the LD for gamma rays was set at 3.5 Gy, while under more dire conditions of war (a bad diet, little medical care, poor nursing) the LD was 2.5 Gy (250 rad). There have been few documented cases of survival beyond 6 Gy. One person at Chernobyl survived a dose of more than 10 Gy, but many of the persons exposed there were not uniformly exposed over their entire body. If a person is exposed in a non-homogeneous manner then a given dose (averaged over the entire body) is less likely to be lethal. For instance, if a person gets a hand/low arm dose of 100 Gy, which gives them an overall dose of 4 Gy, they are more likely to survive than a person who gets a 4 Gy dose over their entire body. A hand dose of 10 Gy or more would likely result in loss of the hand. A British industrial radiographer who was estimated to have received a hand dose of 100 Gy over the course of his lifetime lost his hand because of radiation dermatitis. Most people become ill after an exposure to 1 Gy or more. Fetuses are often more vulnerable to radiation and may miscarry, especially in the first trimester.
One hour after a surface burst, the radiation from fallout in the crater region is 30 grays per hour (Gy/h). Civilian dose rates in peacetime range from 30 to 100 µGy per year.
Fallout radiation decays relatively quickly with time. Most areas become fairly safe for travel and decontamination after three to five weeks.
For yields of up to 10 kt, prompt radiation is the dominant producer of casualties on the battlefield. Humans receiving an acute incapacitating dose (30 Gy) have their performance degraded almost immediately and become ineffective within several hours. However, they do not die until five to six days after exposure, assuming they do not receive any other injuries. Individuals receiving less than a total of 1.5 Gy are not incapacitated. People receiving doses greater than 1.5 Gy become disabled, and some eventually die.
A dose of 5.3 Gy to 8.3 Gy is considered lethal but not immediately incapacitating. Personnel exposed to this amount of radiation have their cognitive performance degraded in two to three hours, depending on how physically demanding the tasks they must perform are, and remain in this disabled state at least two days. However, at that point they experience a recovery period and can perform non-demanding tasks for about six days, after which they relapse for about four weeks. At this time they begin exhibiting symptoms of radiation poisoning of sufficient severity to render them totally ineffective. Death follows at approximately six weeks after exposure, although outcomes may vary. | 0 | Theoretical and Fundamental Chemistry |
Studies published in 2000 considered this hypothetical effect to be responsible for warming events in and at the end of the Last Glacial Maximum. Although periods of increased atmospheric methane match periods of continental-slope failure, later work found that the distinct deuterium/hydrogen (D/H) isotope ratio indicated that wetland methane emissions was the main contributor to atmospheric methane concentrations. While there were major dissociation events during the last deglaciation, with Bølling–Allerød warming triggering the disappearance of the entire methane hydrate deposit in the Barents Sea within 5000 years, those events failed to counteract the onset of a major Younger Dryas cooling period, suggesting that most of the methane stayed within the seawater after being liberated from the seafloor deposits, with very little entering the atmosphere.
In 2008, it was suggested that equatorial permafrost methane clathrate may have had a role in the sudden warm-up of "Snowball Earth", 630 million years ago.
Other events potentially linked to methane hydrate excursions are the Permian–Triassic extinction event and the Paleocene–Eocene Thermal Maximum. | 0 | Theoretical and Fundamental Chemistry |
Like any other plasma protein, levels drop in patients with hepatic disease due to reduced synthesizing capabilities.
Mechanisms of low ceruloplasmin levels:
* Gene expression genetically low (aceruloplasminemia)
* Copper levels are low in general
** Malnutrition/trace metal deficiency in the food source
** Zinc toxicity, due to induced copper deficiency
* Copper does not cross the intestinal barrier due to ATP7A deficiency (Menkes disease and Occipital horn syndrome)
* Delivery of copper into the lumen of the ER-Golgi network is absent in hepatocytes due to absent ATP7B (Wilson's disease)
Copper availability doesn't affect the translation of the nascent protein. However, the apoenzyme without copper is unstable. Apoceruloplasmin is largely degraded intracellularly in the hepatocyte and the small amount that is released has a short circulation half life of 5 hours as compared to the 5.5 days for the holo-ceruloplasmin.
Ceruloplasmin can be measured by means of a blood test; this can be done using immunoassays . The sample is spun and separated; it is stored around 4°C Celsius for three days. This test is to determine if there are signs of Wilson disease. Another test that can be done is a urine copper level test; this has been found to be less accurate than the blood test. A liver tissue test can be done as well.
Mutations in the ceruloplasmin gene (CP), which are very rare, can lead to the genetic disease aceruloplasminemia, characterized by hyperferritinemia with iron overload. In the brain, this iron overload may lead to characteristic neurologic signs and symptoms, such as cerebellar ataxia, progressive dementia, and extrapyramidal signs. Excess iron may also deposit in the liver, pancreas, and retina, leading to cirrhosis, endocrine abnormalities, and loss of vision, respectively. | 1 | Applied and Interdisciplinary Chemistry |
Typically the copper oxhide ingots are highly pure (approximately 99 weight percent copper) with trace element content of less than one weight percent. The few tin oxhide ingots that have been available to study are also exceptionally pure. Microscopic analysis of the Uluburun copper oxhide ingots reveals that they are highly porous. This feature results from the effervescence of gases as the molten metal cooled. Slag inclusions are also present. Their existence implies that slag was not fully removed from the smelted metal and thus that the ingots were made from remelted copper.
Macroscopic observation of the Uluburun copper ingots indicates that they were cast through multiple pours; there are distinct layers of metal in each ingot. Furthermore, the relatively high weight and high purity of the ingots would be difficult to achieve even today in only one pour.
The porosity of the copper ingots and the natural brittleness of tin suggest that both metal ingots were easy to break. As Bass et al. proposes, a metalsmith could simply break off a piece of the ingot whenever he liked for a new casting. | 1 | Applied and Interdisciplinary Chemistry |
Core-electron binding energy (CEBE) shifts correlate linearly with the Hammett substituent constants (σ) in substituted benzene derivatives.
Consider para-disubstituted benzene p-F-CH-Z, where Z is a substituent such as NH, NO, etc. The fluorine atom is para with respect to the substituent Z in the benzene ring. The image on the right shows four distinguished ring carbon atoms, C1(ipso), C2(ortho), C3(meta), C4(para) in p-F-CH-Z molecule. The carbon with Z is defined as C1(ipso) and fluorinated carbon as C4(para). This definition is followed even for Z = H. The left-hand side of () is called CEBE shift or ΔCEBE, and is defined as the difference between the CEBE of the fluorinated carbon atom in p-F-CH-Z and that of the fluorinated carbon in the reference molecule FCH.
The right-hand side of Eq. is a product of a parameter κ and a Hammett substituent constant at the para position, σp. The parameter is defined by eq. :
where and are the Hammett reaction constants for the reaction of the neutral molecule and core ionized molecule, respectively. ΔCEBEs of ring carbons in p-F-CH-Z were calculated with density functional theory to see how they correlate with Hammett σ-constants. Linear plots were obtained when the calculated CEBE shifts at the ortho, meta and para carbon were plotted against Hammett σ, σ and σ constants respectively.
* value calculated ≈ 1.
Hence the approximate agreement in numerical value and in sign between the CEBE shifts and their corresponding Hammett σ constant. | 0 | Theoretical and Fundamental Chemistry |
Schizosaccharomyces pombe is a facultative sexual yeast that can undergo mating when nutrients are limiting. Exposure of S. pombe to hydrogen peroxide, an agent that causes oxidative stress leading to oxidative DNA damage, strongly induces mating, meiosis, and formation of meiotic spores. This finding suggests that meiosis, and particularly meiotic recombination, may be an adaptation for repairing DNA damage. The overall structure of the MAT locus is similar to that in S. cerevisiae. The mating-type switching system is similar, but has evolved independently. | 1 | Applied and Interdisciplinary Chemistry |
The MOT cloud is loaded from a background of thermal vapour, or from an atomic beam, usually slowed down to the capture velocity using a Zeeman slower. However, the trapping potential in a magneto-optical trap is small in comparison to thermal energies of atoms and most collisions between trapped atoms and the background gas supply enough energy to the trapped atom to kick it out of the trap. If the background pressure is too high, atoms are kicked out of the trap faster than they can be loaded, and the trap does not form. This means that the MOT cloud only forms in a vacuum chamber with a background pressure of less than 100 micropascals (10 bar)}. | 0 | Theoretical and Fundamental Chemistry |
Typical pharmacophore features include hydrophobic centroids, aromatic rings, hydrogen bond acceptors or donors, cations, and anions. These pharmacophore points may be located on the ligand itself or may be projected points presumed to be located in the receptor.
The features need to match different chemical groups with similar properties, in order to identify novel ligands. Ligand-receptor interactions are typically "polar positive", "polar negative" or "hydrophobic". A well-defined pharmacophore model includes both hydrophobic volumes and hydrogen bond vectors. | 1 | Applied and Interdisciplinary Chemistry |
Max Speter was born in Beszterce, Austria-Hungary (now Bistrița, Romania), the youngest of seven children, to his Jewish parents Johann Speter and Anna Dollberg. He grew up in Bistrița and graduated in 1900 from the city's German Gymnasium.
Speter began studying engineering at the Budapest University of Technology and Economics. He then moved to Hanover, and completed his studies in Munich where he received his Diploma in Mechanical Engineering. After graduating he worked with Oskar von Miller, founder of the Deutsches Museum, as a member of the museum's founding team. For a while he worked in the chemical industry in Germany and Hungary. Then he was hired as a researcher at the Humboldt University of Berlin, where he also started his Ph.D. thesis. His doctoral advisors were Hans Heinrich Landolt and Walther Nernst, who later won the 1920 Nobel Prize in chemistry. Speter acquired his doctorate in 1910. | 1 | Applied and Interdisciplinary Chemistry |
HPLC has many applications in both laboratory and clinical science. It is a common technique used in pharmaceutical development, as it is a dependable way to obtain and ensure product purity. While HPLC can produce extremely high quality (pure) products, it is not always the primary method used in the production of bulk drug materials. According to the European pharmacopoeia, HPLC is used in only 15.5% of syntheses. However, it plays a role in 44% of syntheses in the United States pharmacopoeia. This could possibly be due to differences in monetary and time constraints, as HPLC on a large scale can be an expensive technique. An increase in specificity, precision, and accuracy that occurs with HPLC unfortunately corresponds to an increase in cost. | 0 | Theoretical and Fundamental Chemistry |
The van der Waals forces arise from interaction between uncharged atoms or molecules, leading not only to such phenomena as the cohesion of condensed phases and physical absorption of gases, but also to a universal force of attraction between macroscopic bodies. | 0 | Theoretical and Fundamental Chemistry |
The existence of a special structure at the ends of chromosomes was independently proposed in 1938 by Hermann Joseph Muller, studying the fruit fly Drosophila melanogaster, and in 1939 by Barbara McClintock, working with maize. Muller observed that the ends of irradiated fruit fly chromosomes did not present alterations such as deletions or inversions. He hypothesized the presence of a protective cap, which he coined "telomeres", from the Greek telos (end) and meros (part).
In the early 1970s, Soviet theorist Alexei Olovnikov first recognized that chromosomes could not completely replicate their ends; this is known as the "end replication problem". Building on this, and accommodating Leonard Hayflick's idea of limited somatic cell division, Olovnikov suggested that DNA sequences are lost every time a cell replicates until the loss reaches a critical level, at which point cell division ends. According to his theory of marginotomy DNA sequences at the ends of telomeres are represented by tandem repeats, which create a buffer that determines the number of divisions that a certain cell clone can undergo. Furthermore, it was predicted that a specialized DNA polymerase (originally called a tandem-DNA-polymerase) could extend telomeres in immortal tissues such as germ line, cancer cells and stem cells. It also followed from this hypothesis that organisms with circular genome, such as bacteria, do not have the end replication problem and therefore do not age.
In 1975–1977, Elizabeth Blackburn, working as a postdoctoral fellow at Yale University with Joseph G. Gall, discovered the unusual nature of telomeres, with their simple repeated DNA sequences composing chromosome ends. Blackburn, Carol Greider, and Jack Szostak were awarded the 2009 Nobel Prize in Physiology or Medicine for the discovery of how chromosomes are protected by telomeres and the enzyme telomerase. | 1 | Applied and Interdisciplinary Chemistry |
Transketolase activity is decreased in deficiency of thiamine, which in general is due to malnutrition. Several diseases are associated with thiamine deficiency, including beriberi, biotin-thiamine-responsive basal ganglia disease (BTBGD), Wernicke–Korsakoff syndrome, and others (see thiamine for a comprehensive listing).
In Wernicke–Korsakoff syndrome, while no mutations could be demonstrated, there is an indication that thiamine deficiency leads to Wernicke–Korsakoff syndrome only in those whose transketolase has a reduced affinity for thiamine. In this way, the activity of transketolase is greatly hindered, and, as a consequence, the entire pentose phosphate pathway is inhibited.
In Transketolase Deficiency, also known as SDDHD (Short Stature, Developmental Delay, and congenital Heart Defects), the disease is caused by an inherited autosomal recessive mutation in the TKT gene. A rare disorder of pentose phosphate metabolism with symptoms apparent in infancy including developmental delay and intellectual disability, delayed or absent speech, short stature, and congenital heart defects. Additional reported features include hypotonia, hyperactivity, stereotypic behavior, ophthalmologic abnormalities, hearing impairment, and variable facial dysmorphism, among others. Laboratory analysis shows elevated plasma and urinary polyols (erythritol, arabitol, and ribitol) and urinary sugar-phosphates (ribose-5-phosphate and xylulose/ribulose-5-phosphate). "Cell extracts from all 5 patients showed absent or low residual TKT activity. Boyle et al. (2016) suggested that the low TKT activity in some tissues, possibly from another protein with the same function, might explain why TKT deficiency is compatible with life even though TKT is an essential enzyme." | 0 | Theoretical and Fundamental Chemistry |
Pyridine ring forms a hexagon. Slight variations of the and distances as well as the bond angles are observed. | 0 | Theoretical and Fundamental Chemistry |
TLC is a useful tool for reaction monitoring. For this, the plate normally contains a spot of starting material, a spot from the reaction mixture, and a co-spot (or cross-spot) containing both. The analysis will show if the starting material disappeared and if any new products appeared. This provides a quick and easy way to estimate how far a reaction has proceeded. In one study, TLC has been applied in the screening of organic reactions. The researchers react an alcohol and a catalyst directly in the co-spot of a TLC plate before developing it. This provides quick and easy small-scale testing of different reagents.
Compound characterization with TLC is also possible and is similar to reaction monitoring. However, rather than spotting with starting material and reaction mixture, it is with an unknown and a known compound. They may be the same compound if both spots have the same R and look the same under the chosen visualization method. However, co-elution complicates both reaction monitoring and characterization. This is because different compounds will move to the same spot on the plate. In such cases, different solvent mixtures may provide better separation. | 0 | Theoretical and Fundamental Chemistry |
After receiving his Ph.D., Herman T. Briscoe was appointed assistant professor of chemistry at Indiana University, working his way to professor of chemistry in 1928. Throughout his career, Briscoe authored or coauthored 23 publications on conductivity, physical properties, and the reactions of organic and inorganic molecules, supervised the graduate studies of 25 students, and published several general chemistry textbooks.
In 1938, President of Indiana University Herman B. Wells appointed Briscoe as the secretary of the newly established self-survey committee, which sought the feedback of faculty and proposed administrative changes accordingly. In the same year, Briscoe was appointed Chairman of the Department of Chemistry of Indiana University following the recommendation of retiring Chairman Robert E. Lyons. Herman Briscoe would continue on to become Indiana University's first Dean of Faculties in 1939 and Vice President of Indiana University in 1940. Briscoe gave up his appointment as Chairman of the Department of Chemistry in order to focus on his administrative roles as Vice President and Dean of Faculties, in which he served until his retirement in 1959. | 0 | Theoretical and Fundamental Chemistry |
The Goldich dissolution series is a method of predicting the relative stability or weathering rate of common igneous minerals on the Earth's surface, with minerals that form at higher temperatures and pressures less stable on the surface than minerals that form at lower temperatures and pressures. | 0 | Theoretical and Fundamental Chemistry |
Peroxisomes are small (0.1–1 µm diameter) subcellular compartments (organelles) with a fine, granular matrix and surrounded by a single biomembrane which are located in the cytoplasm of a cell. Compartmentalization creates an optimized environment to promote various metabolic reactions within peroxisomes required to sustain cellular functions and viability of the organism.
The number, size and protein composition of peroxisomes are variable and depend on cell type and environmental conditions. For example, in bakers yeast (S. cerevisiae'), it has been observed that, with good glucose supply, only a few, small peroxisomes are present. In contrast, when the yeasts were supplied with long-chain fatty acids as sole carbon source up to 20 to 25 large peroxisomes can be formed. | 1 | Applied and Interdisciplinary Chemistry |
Although the phenomenon of EDHF has been observed and reported in scientific literature, to date the chemical identity of the factor(s) has not been determined.
* In some cases, members of a class of arachidonic acid derivatives, the epoxyeicosatrienoic acids (EETs), have been found to mediate the vasodilation. These compounds are formed by epoxidation of any one of four double bonds of the arachidonic acid carbon backbone by cytochrome P450 epoxygenase enzymes.
* In addition, in some cases hydrogen peroxide has been suggested to function as an EDHF in some vascular beds; although the validity of this observation is debated because it may have an inhibitory action on K+ channels, at least, in some vascular beds.
* It has been suggested that EDHF is potassium ions (K), as the activation of endothelial K-Ca channels causes an efflux of K from endothelial cells toward the extracellular space. An increase in extracellular K has been shown to activate an ouabain-sensitive electrogenic Na–K-ATPase followed by hyperpolarization and smooth muscle cell relaxation. However, the involvement of K ions in EDHF-mediated relaxation does not necessarily involve the activation Na–K-ATPase channels. It is more likely that K ions and gap junctions can be involved in EDHF-mediated relaxation simultaneously, and may also act synergistically.
* Subsequently, it was suggested that EDHF is a sulfur signal that results in activation of K channels via sulfhydration of a cysteine residue (formation of a cysteine persulfide) (https://doi.org/10.1161/CIRCRESAHA.111.240242)
* C-type natriuretic peptide (CNP) has been shown to exert a variety of cardiovascular effects including vasodilation and hyperpolarization of arteries through the opening of K-channels. CNP is widely distributed in the cardiovascular system and it has been found at high concentrations, in particular in endothelial cells. Endothelium-derived CNP has been proposed to act as an EDHF via specific C-subtype of natriuretic peptide receptor, however the evidence in favour of CNP's acting as EDHF has yet to be determined.
* An alternative explanation for the EDHF phenomenon is that direct intercellular communication via gap junctions allows passive spread of agonist-induced endothelial hyperpolarization through the vessel wall. In some arteries, eicosanoids and K+ ions may themselves initiate a conducted endothelial hyperpolarization, thus suggesting that electrotonic signalling may represent a general mechanism through which the endothelium participates in the regulation of vascular tone. | 1 | Applied and Interdisciplinary Chemistry |
Low shear strength has been the primary reason for limited range of applications. In the absence of external pressure the maximum shear strength is about 100 kPa. If the fluid is compressed in the magnetic field direction and the compressive stress is 2 MPa, the shear strength is raised to 1100 kPa. If the standard magnetic particles are replaced with elongated magnetic particles, the shear strength is also improved. | 1 | Applied and Interdisciplinary Chemistry |
Plasma transferred wire arc (PTWA) thermal spraying is a thermal spraying process that deposits a coating on the internal surface of a cylindrical surface, or external surface of any geometry. It is predominantly known for its use in coating the cylinder bores of an internal combustion engine, enabling the construction of aluminium engine blocks without cast iron cylinder sleeves.
The inventors of PTWA received the 2009 IPO National Inventor of the Year award. This technology was initially patented and developed by Flame-Spray Industries, and subsequently improved upon by Flame-Spray and Ford. | 1 | Applied and Interdisciplinary Chemistry |
The lotus effect refers to self-cleaning properties that are a result of ultrahydrophobicity as exhibited by the leaves of Nelumbo, the lotus flower. Dirt particles are picked up by water droplets due to the micro- and nanoscopic architecture on the surface, which minimizes the droplets adhesion to that surface. Ultrahydrophobicity and self-cleaning properties are also found in other plants, such as Tropaeolum (nasturtium), Opuntia (prickly pear), Alchemilla', cane, and also on the wings of certain insects.
The phenomenon of ultrahydrophobicity was first studied by Dettre and Johnson in 1964 using rough hydrophobic surfaces. Their work developed a theoretical model based on experiments with glass beads coated with paraffin or PTFE telomer. The self-cleaning property of ultrahydrophobic micro-nanostructured surfaces was studied by Wilhelm Barthlott and Ehler in 1977, who described such self-cleaning and ultrahydrophobic properties for the first time as the "lotus effect"; perfluoroalkyl and perfluoropolyether ultrahydrophobic materials were developed by Brown in 1986 for handling chemical and biological fluids. Other biotechnical applications have emerged since the 1990s. | 0 | Theoretical and Fundamental Chemistry |
Alzheimer’s is a neurodegenerative disease involving progressive memory loss and other declines in brain function. One common cause of familial Alzheimer’s is mutation in the PSEN1 gene. This gene encodes a protein that cleaves certain intracellular peptides which, once free in the cytoplasm, promote CBP<nowiki/>degradation. Mutations in PSEN1 decrease its production or ability to cleave proteins. This derepresses the CBP proteins, and allows them to perform their function of upregulating transcription of their target genes. | 1 | Applied and Interdisciplinary Chemistry |
Cycloalkanes and aromatic compounds can be treated as the main parent chain of the compound, in which case the positions of substituents are numbered around the ring structure. For example, the three isomers of xylene , commonly the ortho-, meta-, and para- forms, are 1,2-dimethylbenzene, 1,3-dimethylbenzene, and 1,4-dimethylbenzene. The cyclic structures can also be treated as functional groups themselves, in which case they take the prefix "cycloalkyl-" (e.g. "cyclohexyl-") or for benzene, "phenyl-".
The IUPAC nomenclature scheme becomes rapidly more elaborate for more complex cyclic structures, with notation for compounds containing conjoined rings, and many common names such as phenol being accepted as base names for compounds derived from them. | 0 | Theoretical and Fundamental Chemistry |
* [https://archive.org/details/essaysphysicala00lavogoog Essays Physical and Chemical] (London: for Joseph Johnson, 1776; London: Frank Cass and Company Ltd., 1970) translation by Thomas Henry of Opuscules physiques et chimiques
* The Art of Manufacturing Alkaline Salts and Potashes, Published by Order of His Most Christian Majesty, and approved by the Royal Academy of Sciences (1784) trans. by Charles Williamos of Lart de fabriquer le salin et la potasse'
* (with Pierre-Simon Laplace) Memoir on Heat: Read to the Royal Academy of Sciences, 28 June 1783, by Messrs. Lavoisier & De La Place of the same Academy. (New York: Neale Watson Academic Publications, 1982) trans. by Henry Guerlac of Mémoire sur la chaleur
* [https://archive.org/details/essaysoneffects00henrgoog Essays, on the Effects Produced by Various Processes On Atmospheric Air; With A Particular View To An Investigation Of The Constitution Of Acids], trans. Thomas Henry (London: Warrington, 1783) collects these essays:
# "Experiments on the Respiration of Animals, and on the Changes effected on the Air in passing through their Lungs." (Read to the Académie des Sciences, 3 May 1777)
# "On the Combustion of Candles in Atmospheric Air and in Dephlogistated Air." (Communicated to the Académie des Sciences, 1777)
# "On the Combustion of Kunckel's Phosphorus."
# "On the Existence of Air in the Nitrous Acid, and on the Means of decomposing and recomposing that Acid."
# "On the Solution of Mercury in Vitriolic Acid."
# "Experiments on the Combustion of Alum with Phlogistic Substances, and on the Changes effected on Air in which the Pyrophorus was burned."
# "On the Vitriolisation of Martial Pyrites."
# "General Considerations on the Nature of Acids, and on the Principles of which they are composed."
# "On the Combination of the Matter of Fire with Evaporable Fluids; and on the Formation of Elastic Aëriform Fluids."
* “Reflections on Phlogiston”, translation by Nicholas W. Best of “Réflexions sur le phlogistique, pour servir de suite à la théorie de la combustion et de la calcination” (read to the Académie Royale des Sciences over two nights, 28 June and 13 July 1783). Published in two parts:
* Method of chymical nomenclature: proposed by Messrs. De Moreau, Lavoisier, Bertholet, and De Fourcroy (1788) [http://web.lemoyne.edu/~giunta/nomenclature.html Dictionary]
* Elements of Chemistry, in a New Systematic Order, Containing All the Modern Discoveries (Edinburgh: William Creech, 1790; New York: Dover, 1965) translation by Robert Kerr of Traité élémentaire de chimie. (Dover).
** [https://archive.org/details/elementschemist00kerrgoog 1799 edition]
** 1802 edition: [https://archive.org/details/elementschemist01lavogoog volume 1], [https://archive.org/details/elementschemist00lavogoog volume 2]
** [http://gallica.bnf.fr/ark:/12148/btv1b21000856.r=lavoisier.langEN Some illustrations] from 1793 edition
** [http://othmerlib.sciencehistory.org/record=b1034183~S2 Some more illustrations] from the Science History Institute
** [http://othmerlib.sciencehistory.org/record=b1034193~S2 More illustrations] (from Collected Works) from the Science History Institute | 1 | Applied and Interdisciplinary Chemistry |
Constructed wetlands have been used extensively for the removal of dissolved metals and metalloids. Although these contaminants are prevalent in mine drainage, they are also found in stormwater, landfill leachate and other sources (e.g., leachate or FDG washwater at coal-fired power plants), for which treatment wetlands have been constructed for mines. | 1 | Applied and Interdisciplinary Chemistry |
Small molecules that are able to inhibit TGF-β induced EMT are under development. Silmitasertib (CX-4945) is a small molecule inhibitor of protein kinase CK2, which has been supported to be linked with TGF-β induced EMT, and is currently in clinical trials for cholangiocarcinoma (bile duct cancer), as well as in preclinical development for hematological and lymphoid malignancies. In January 2017, Silmitasertib was granted orphan drug status by the U.S. Food and Drug Administration for cholangiocarcinoma and is currently in phase II study. Silmitasertib is being developed by Senhwa Biosciences. Another small molecule inhibitor Galunisertib (LY2157299) is a potent TGF-β type I receptor kinase inhibitor that was demonstrated to reduce the size, the growth rate of tumors, and the tumor forming potential in triple negative breast cancer cell lines using mouse xenografts. Galunisertib is currently being developed by Lilly Oncology and is in phase I/II clinical trials for hepatocellular carcinoma, unresectable pancreatic cancer, and malignant glioma. Small molecule inhibitors of EMT are suggested to not act as a replacement for traditional chemotherapeutic agents but are likely to display the greatest efficacy in treating cancers when used in conjunction with them.
Antagomirs and microRNA mimics have gained interest as a potential source of therapeutics to target EMT induced metastasis in cancer as well as treating many other diseases. Antagomirs were first developed to target miR-122, a microRNA that was abundant and specific to the liver, and this discovery has led to the development of other antagomirs that can pair with specific microRNAs present in the tumor microenvironment or in the cancer cells. A microRNA mimic to miR-655 was found to suppress EMT through the targeting of EMT inducing transcription factor ZEB1 and TGF-β receptor 2 in a pancreatic cancer cell line. Overexpression of the miR-655 mimic in the Panc1 cancer cell line upregulated the expression of E-cadherin and suppressed the migration and invasion of mesenchymal-like cancer cells. The use of microRNA mimics to suppress EMT has expanded to other cancer cell lines and holds potential for clinical drug development. However, microRNA mimics and antagomirs suffer from a lack of stability in vivo and lack an accurate delivery system to target these molecules to the tumor cells or tissue for treatment. Improvements to antagomir and microRNA mimic stability through chemical modifications such as locked nucleic acid (LNA) oligonucleotides or peptide nucleic acids (PNA) can prevent the fast clearing of these small molecules by RNases. Delivery of antagomirs and microRNA mimics into cells by enclosing these molecules in liposome-nanoparticles has generated interest however liposome structures suffer from their own drawbacks that will need to be overcome for their effective use as a drug delivery mechanism. These drawbacks of liposome-nanoparticles include nonspecific uptake by cells and induction of immune responses. The role that microRNAs play in cancer development and metastasis is under much scientific investigation and it is yet to be demonstrated whether microRNA mimics or antagomirs may serve as standard clinical treatments to suppress EMT or oncogenic microRNAs in cancers. | 1 | Applied and Interdisciplinary Chemistry |
In metallurgy, refining consists of purifying an impure metal. It is to be distinguished from other processes such as smelting and calcining in that those two involve a chemical change to the raw material, whereas in refining, the final material is usually identical chemically to the original one, only it is purer. The processes used are of many types, including pyrometallurgical and hydrometallurgical techniques. | 1 | Applied and Interdisciplinary Chemistry |
In Cartesian coordinates the 2 basis vectors are represented by a cell tensor :
The area of the unit cell, , is given by the determinant of the cell matrix:
For the special case of a square or rectangular unit cell, the matrix is diagonal, and we have that: | 0 | Theoretical and Fundamental Chemistry |
Dai has received several honors and awards, among them:
* 1985: Camille and Henry Dreyfus Foundation New Faculty Award
* 1988: Sloan Fellowship
* 1989: The Camille and Henry Dreyfus Foundation Teacher-Scholar Award
* 1990: Coblentz Award in Spectroscopy
* 1992: Fellowship of the American Physical Society
* 1994: Alexander von Humboldt Award for Senior US Scientists
* 1995: Philadelphia Section Award, American Chemical Society
* 2000: Guggenheim Fellowship
* 2006: Ellis Lippincott Award for Spectroscopy of the Optical Society of America
* 2009: Distinguished Achievement Award, the Institute of Chinese Engineers in the U.S.
* 2010: Fellowship of the American Chemical Society
* 2012: Langmuir Lecturer Award, Division of Colloid and Surface Chemistry, American Chemical Society
* 2013: Michael P. Malone International Leadership Award, Association of Public and Land Grant Universities
* 2017: Knight Order of the Italian Star, Government of Italy
* 2017: Distinguished Alumni Award, National Taiwan University
* 2019: Hai-Lung Dai Festschrift, Journal of Physical Chemistry, American Chemical Society | 0 | Theoretical and Fundamental Chemistry |
1. Comprehensive Conversion: The reactor converts all organic compounds to methane, whereas traditional methanizers typically only convert CO and CO2. This comprehensive conversion results in a more uniform response and more sensitive detection for a wider range of organic species.
2. Resilience to Poisoning: The reactor is more resilient to poisoning by compounds containing nitrogen and oxygen compared to traditional methanizers. This means that it can maintain its performance and efficiency even in the presence of potentially interfering compounds.
3. Sharper Peaks: When compared with packed column versions of methanizers, the reactor typically produces sharper peaks. Sharper peaks enhance resolution and can improve the accuracy and reliability of chromatographic analysis.
Overall, these benefits make post-column oxidation-reduction reactors an attractive choice for gas chromatography applications where comprehensive conversion, resistance to poisoning, and peak sharpness are essential. | 0 | Theoretical and Fundamental Chemistry |
Trail pheromones are semiochemicals secreted from the body of an individual to affect the behavior of another individual receiving it. Trail pheromones often serve as a multi purpose chemical secretion that leads members of its own species towards a food source, while representing a territorial mark in the form of an allomone to organisms outside of their species. Specifically, trail pheromones are often incorporated with secretions of more than one exocrine gland to produce a higher degree of specificity. Considered one of the primary chemical signaling methods in which many social insects depend on, trail pheromone deposition can be considered one of the main facets to explain the success of social insect communication today. Many species of ants, including those in the genus Crematogaster use trail pheromones. | 1 | Applied and Interdisciplinary Chemistry |
Its principal utility is that it provides simple predictions of phase equilibrium based on a single parameter that is readily obtained for most materials. These predictions are often useful for nonpolar and slightly polar (dipole moment < 2 debyes) systems without hydrogen bonding. It has found particular use in predicting solubility and swelling of polymers by solvents. More complicated three-dimensional solubility parameters, such as Hansen solubility parameters, have been proposed for polar molecules.
The principal limitation of the solubility parameter approach is that it applies only to associated solutions ("like dissolves like" or, technically speaking, positive deviations from Raoults law): it cannot account for negative deviations from Raoults law that result from effects such as solvation or the formation of electron donor–acceptor complexes. Like any simple predictive theory, it can inspire overconfidence: it is best used for screening with data used to verify the predictions. | 0 | Theoretical and Fundamental Chemistry |
Addition across the unsaturated carbon-carbon bond can be Markovnikov or anti-Markovnikov depending on the catalyst. When considering the possibly of R/S chirality, four products can be obtained: Markovnikov with R or S and anti-Markovnikov addition with R or S. Although there have been many reports of catalytic hydroamination with a wide range of metals, there are far fewer describing enantioselective catalysis to selectively make one of the four possible products. Recently, there have been reports of selectively making the thermodynamic or kinetic product, which can be related to the racemic Markovnikov or anti-Markovnikov structures (see Thermodynamic and Kinetic Product below). | 0 | Theoretical and Fundamental Chemistry |
Non-explosive demolition agents are chemicals that are an alternative to explosives and gas pressure blasting products in demolition, mining, and quarrying. To use non-explosive demolition agents in demolition or quarrying, holes are drilled in the base rock as they would be for use with conventional explosives. A slurry mixture of the non-explosive demolition agent and water is poured into the drill holes. Over the next few hours the slurry expands, cracking the rock in a pattern somewhat like the cracking that would occur from conventional explosives.
Non-explosive demolition agents offer many advantages including that they are silent and do not produce vibration the way a conventional explosive would. In some applications conventional explosives are more economical than non-explosive demolition agents. In many countries these are available without restriction, unlike explosives which are highly regulated.
The active ingredient is typically calcium oxide, "burnt lime," and is typically mixed with Portland cement and modifiers.
These agents are much safer than explosives, but they have to be used as directed to avoid steam explosions during the first few hours after being placed.
Many patents describe non-explosive demolition agents containing CaO, SiO and/or cement. | 1 | Applied and Interdisciplinary Chemistry |
* R. H. Perry, C. H. Chilton, C. W. Green (ed.), Perrys Chemical Engineers Handbook (7th Ed), McGraw-Hill (1997), sections 12.56-12.60, 23.60, .
* K. E. Peray, The Rotary Cement Kiln, CHS Press (1998), .
* Boateng, Akwasi, Rotary kilns: transport phenomena and transport processes. Amsterdam; Boston: Elsevier/Butterworth-Heinemann (2008), . | 1 | Applied and Interdisciplinary Chemistry |
The van der Waals force between two molecules, in this context, is the sum of the attractive or repulsive forces between them; these forces are primarily electrostatic in nature, and in their simplest form might consist of a force between two charges, two dipoles, or between a charge and a dipole. Thus, the strength of the force may often depend on the net charge, electric dipole moment, or the electric polarizability () (see for example London force) of the molecules, with highly polarizable molecules contributing to stronger forces, and so on.
The total force between two bodies, each consisting of many molecules in the van der Waals theory is simply the sum of the intermolecular van der Waals forces, where pairwise additivity is assumed. That is to say, the forces are summed as though each pair of molecules interacts completely independently of their surroundings (See Van der Waals forces between Macroscopic Objects for an example of such a treatment). This assumption is usually correct for gasses, but presents a problem for many condensed materials, as it is known that the molecular interactions may depend strongly on their environment and neighbors. For example, in a conductor, a point-like charge might be screened by the electrons in the conductance band, and the polarizability of a condensed material may be vastly different from that of an individual molecule. In order to correctly predict the van der Waals forces of condensed materials, a theory that takes into account their total electrostatic response is needed. | 0 | Theoretical and Fundamental Chemistry |
Under homeostasis, the reactivity of heme is controlled by its insertion into the "heme pockets" of hemoproteins. Under oxidative stress however, some hemoproteins, e.g. hemoglobin, can release their heme prosthetic groups. The non-protein-bound (free) heme produced in this manner becomes highly cytotoxic, most probably due to the iron atom contained within its protoporphyrin IX ring, which can act as a Fenton's reagent to catalyze in an unfettered manner the production of free radicals. It catalyzes the oxidation and aggregation of protein, the formation of cytotoxic lipid peroxide via lipid peroxidation and damages DNA through oxidative stress. Due to its lipophilic properties, it impairs lipid bilayers in organelles such as mitochondria and nuclei. These properties of free heme can sensitize a variety of cell types to undergo programmed cell death in response to pro-inflammatory agonists, a deleterious effect that plays an important role in the pathogenesis of certain inflammatory diseases such as malaria and sepsis. | 1 | Applied and Interdisciplinary Chemistry |
The Ellis R. Lippincott Award is awarded annually to recognize "an individual who has made significant contributions to vibrational spectroscopy as judged by his or her influence on other scientists."
It was jointly established in 1975 by The Optical Society, The Coblentz Society, and The Society for Applied Spectroscopy. The award honors Ellis R. Lippincott, a vibrational spectroscopist who worked at the University of Maryland. Lippincott was one of the developers of the Diamond anvil cell, which is used in high pressure research. | 0 | Theoretical and Fundamental Chemistry |
A run-around coil is a type of energy recovery heat exchanger most often positioned within the supply and exhaust air streams of an air handling system, or in the exhaust gases of an industrial process, to recover the heat energy. Generally, it refers to any intermediate stream used to transfer heat between two streams that are not directly connected for reasons of safety or practicality. It may also be referred to as a run-around loop, a pump-around coil or a liquid coupled heat exchanger. | 0 | Theoretical and Fundamental Chemistry |
Inhalation of chloromethane gas produces central nervous system effects similar to alcohol intoxication. The TLV is 50 ppm and the MAC is the same. Prolonged exposure may have mutagenic effects. | 1 | Applied and Interdisciplinary Chemistry |
In rat liver, the total amount of NAD and NADH is approximately 1 μmole per gram of wet weight, about 10 times the concentration of NADP and NADPH in the same cells. The actual concentration of NAD in cell cytosol is harder to measure, with recent estimates in animal cells ranging around 0.3 mM, and approximately 1.0 to 2.0 mM in yeast. However, more than 80% of NADH fluorescence in mitochondria is from bound form, so the concentration in solution is much lower.
NAD concentrations are highest in the mitochondria, constituting 40% to 70% of the total cellular NAD. NAD in the cytosol is carried into the mitochondrion by a specific membrane transport protein, since the coenzyme cannot diffuse across membranes. The intracellular half-life of NAD was claimed to be between 1–2 hours by one review, whereas another review gave varying estimates based on compartment: intracellular 1–4 hours, cytoplasmic 2 hours, and mitochondrial 4–6 hours.
The balance between the oxidized and reduced forms of nicotinamide adenine dinucleotide is called the NAD/NADH ratio. This ratio is an important component of what is called the redox state of a cell, a measurement that reflects both the metabolic activities and the health of cells. The effects of the NAD/NADH ratio are complex, controlling the activity of several key enzymes, including glyceraldehyde 3-phosphate dehydrogenase and pyruvate dehydrogenase. In healthy mammalian tissues, estimates of the ratio of free NAD to NADH in the cytoplasm typically lie around 700:1; the ratio is thus favorable for oxidative reactions. The ratio of total NAD/NADH is much lower, with estimates ranging from 3–10 in mammals. In contrast, the NADP/NADPH ratio is normally about 0.005, so NADPH is the dominant form of this coenzyme. These different ratios are key to the different metabolic roles of NADH and NADPH. | 0 | Theoretical and Fundamental Chemistry |
Total dissolved solids (TDS) is a measure of the dissolved combined content of all inorganic and organic substances present in a liquid in molecular, ionized, or micro-granular (colloidal sol) suspended form. TDS are often measured in parts per million (ppm). TDS in water can be measured using a digital meter.
Generally, the operational definition is that the solids must be small enough to survive filtration through a filter with 2-micrometer (nominal size, or smaller) pores. Total dissolved solids are normally discussed only for freshwater systems, as salinity includes some of the ions constituting the definition of TDS. The principal application of TDS is in the study of water quality for streams, rivers, and lakes. Although TDS is not generally considered a primary pollutant (e.g. it is not deemed to be associated with health effects), it is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants.
Primary sources for TDS in receiving waters are agricultural runoff and residential (urban) runoff, clay-rich mountain waters, leaching of soil contamination, and point source water pollution discharge from industrial or sewage treatment plants. The most common chemical constituents are calcium, phosphates, nitrates, sodium, potassium, and chloride, which are found in nutrient runoff, general stormwater runoff and runoff from snowy climates where road de-icing salts are applied. The chemicals may be cations, anions, molecules or agglomerations on the order of one thousand or fewer molecules, so long as a soluble micro-granule is formed. More exotic and harmful elements of TDS are pesticides arising from surface runoff. Certain naturally occurring total dissolved solids arise from the weathering and dissolution of rocks and soils. The United States has established a secondary water quality standard of 500 mg/L to provide for palatability of drinking water.
Total dissolved solids are differentiated from total suspended solids (TSS), in that the latter cannot pass through a sieve of 2 micrometers and yet are indefinitely suspended in solution. The term settleable solids refers to material of any size that will not remain suspended or dissolved in a holding tank not subject to motion, and excludes both TDS and TSS. Settleable solids may include larger particulate matter or insoluble molecules.
Total dissolved solids include both volatile and non-volatile solids. Volatile solids are ones that can easily go from a solid to a gaseous state. Non-volatile solids must be heated to a high temperature, typically 550 °C, in order to achieve this state change. Examples of non-volatile substances include salts and sugars. | 1 | Applied and Interdisciplinary Chemistry |
In accordance with the terms of IOP purchase, Fulmer's capital investment in new facilities was expected to be financed from profit and Fulmer would make a modest annual contribution to IOP funds.
However, Fulmer's recent expansion and its large investment in capital equipment required increasing bank borrowing. Considerable management effort and other resources had been taken up with the transfer of facilities between Fulmer, Chessington, Ashtead, Redhill and Slough and there had been a damaging fire at Ashtead.
It was clear that alternative sources of finance were needed. A management buyout was explored and found to be not feasible. Preparations were made for a stock exchange flotation but, in the late 1980s Fulmer sustained large losses and plans to float were postponed.
The balance of Fulmer's activities had changed. Academic research was now a minor part of its work. Most of its income came from testing, consultancy and small scale manufacture. The IOP were becoming concerned that their ownership of Fulmer as a commercial organization might be judged incompatible with their charitable status as a learned society. They were also concerned that Fulmer was making losses and had a growing overdraft. The IOP Council finally decided to sell Fulmer. | 1 | Applied and Interdisciplinary Chemistry |
Dexketoprofen is the (S)-enantiomer of ketoprofen. Technically it is a chiral switch of (±)-ketoprofen. The switch was done for a faster onset of action, a better therapeutic value. Dexketoprofen consists of a propionic acid moiety connected to a benzophenone molecule by its second carbon. | 0 | Theoretical and Fundamental Chemistry |
With an active surface area of 160 cm, the nasal cavity is another noteworthy route of mucoadhesive administration. Due to the sweeping motion of the cilia that lines the mucosa, nasal mucus has a quick turnover of 10 to 15 minutes. Because of this, the nasal cavity is most suitable for rapid, local medicinal dosages. Additionally, its close proximity to the blood–brain barrier makes it a convenient route for administering specialized drugs to the central nervous system. Gels, solutions, and aerosols are common dosage forms in the nasal cavity. However, recent research into particles and microspheres have shown increased bioavailability over non-solid forms of medicine largely due to the use of mucoadhesives. | 1 | Applied and Interdisciplinary Chemistry |
dNovo, a Silicon-valley based company, was founded in 2018 and participated in the Y Combinator accelerator. The company has demonstrated its technology by growing a patch of human hair on a mouse. | 1 | Applied and Interdisciplinary Chemistry |
Bird populations are one of many indicators of herbicide damage.Most observed effects are due not to toxicity, but to habitat changes and the decreases in abundance of species on which birds rely for food or shelter. Herbicide use in silviculture, used to favor certain types of growth following clearcutting, can cause significant drops in bird populations. Even when herbicides which have low toxicity to birds are used, they decrease the abundance of many types of vegetation on which the birds rely. Herbicide use in agriculture in the UK has been linked to a decline in seed-eating bird species which rely on the weeds killed by the herbicides. Heavy use of herbicides in neotropical agricultural areas has been one of many factors implicated in limiting the usefulness of such agricultural land for wintering migratory birds. | 1 | Applied and Interdisciplinary Chemistry |
Siderophores, natural or synthetic, can chelate metal ions other than iron ions. Examples include aluminium, gallium, chromium, copper, zinc, lead, manganese, cadmium, vanadium, zirconium, indium, plutonium, berkelium, californium, and uranium. | 1 | Applied and Interdisciplinary Chemistry |
Ammonia oxidation to nitrate in a single step within one organism was predicted in 2006 and discovered in 2015 in the species Nitrospira inopinata. A pure culture of the organism was obtained in 2017, representing a revolution in our understanding of the nitrification process. | 1 | Applied and Interdisciplinary Chemistry |
* Group 14 anions functionalized with organic groups: [GeMes], [Ge(CHCHCHNH)], [(CHCH)GeGe(CHCH)], [Ge(CHCHCHCH)Ge], [(CHCH)Ge(CH)Ge(CHCH)];
* Silated anions: GeHypTl, [GeHyp];
* Intermetalloid deltahedral clusters: [Co@Sn], [Ni@Pb], [Au@Pb], [Mn@Pb], [Rh@Sn];
* Exo coordinated transition metal complexes: [(ŋ-Sn)Hg(ŋ-Sn)], [GeNi(CO)], [SnTiCp], [(tol)NbSnNb(tol)];
* [NiSb] (NiSb ring inside Sb bowl). | 0 | Theoretical and Fundamental Chemistry |
Thermal conduction property of any gas under standard conditions of pressure and temperature is a fixed quantity. This property of a known reference gas or known reference gas mixtures can, therefore, be used for certain sensory applications, such as the thermal conductivity analyzer.
The working of this instrument is by principle based on the Wheatstone bridge containing four filaments whose resistances are matched. Whenever a certain gas is passed over such network of filaments, their resistance changes due to the altered thermal conductivity of the filaments and thereby changing the net voltage output from the Wheatstone Bridge. This voltage output will be correlated with the database to identify the gas sample. | 1 | Applied and Interdisciplinary Chemistry |
Treatment decisions often follow formal or informal algorithmic guidelines. Treatment options can often be ranked or prioritized into lines of therapy: first-line therapy, second-line therapy, third-line therapy, and so on. First-line therapy (sometimes referred to as induction therapy, primary therapy, or front-line therapy) is the first therapy that will be tried. Its priority over other options is usually either: (1) formally recommended on the basis of clinical trial evidence for its best-available combination of efficacy, safety, and tolerability or (2) chosen based on the clinical experience of the physician. If a first-line therapy either fails to resolve the issue or produces intolerable side effects, additional (second-line) therapies may be substituted or added to the treatment regimen, followed by third-line therapies, and so on.
An example of a context in which the formalization of treatment algorithms and the ranking of lines of therapy is very extensive is chemotherapy regimens. Because of the great difficulty in successfully treating some forms of cancer, one line after another may be tried. In oncology the count of therapy lines may reach 10 or even 20.
Often multiple therapies may be tried simultaneously (combination therapy or polytherapy). Thus combination chemotherapy is also called polychemotherapy, whereas chemotherapy with one agent at a time is called single-agent therapy or monotherapy.
Adjuvant therapy is therapy given in addition to the primary, main, or initial treatment, but simultaneously (as opposed to second-line therapy). Neoadjuvant therapy is therapy that is begun before the main therapy. Thus one can consider surgical excision of a tumor as the first-line therapy for a certain type and stage of cancer even though radiotherapy is used before it; the radiotherapy is neoadjuvant (chronologically first but not primary in the sense of the main event). Premedication is conceptually not far from this, but the words are not interchangeable; cytotoxic drugs to put a tumor "on the ropes" before surgery delivers the "knockout punch" are called neoadjuvant chemotherapy, not premedication, whereas things like anesthetics or prophylactic antibiotics before dental surgery are called premedication.
Step therapy or stepladder therapy is a specific type of prioritization by lines of therapy. It is controversial in American health care because unlike conventional decision-making about what constitutes first-line, second-line, and third-line therapy, which in the U.S. reflects safety and efficacy first and cost only according to the patient's wishes, step therapy attempts to mix cost containment by someone other than the patient (third-party payers) into the algorithm. Therapy freedom and the negotiation between individual and group rights are involved. | 1 | Applied and Interdisciplinary Chemistry |
The FiSER (filament stretching extensional rheometer) is based on the works by Sridhar et al. and Anna et al. In this instrument, a set of linear motors drive a fluid filament apart at an exponentially increasing velocity while measuring force and diameter as a function of time and position. By deforming at an exponentially increasing rate, a constant strain rate can be achieved in the samples (barring endplate flow limitations). This system can monitor the strain-dependent extensional viscosity, as well as stress decay following flow cessation. A detailed presentation on the various uses of filament stretching rheometry can be found on the MIT web site. | 1 | Applied and Interdisciplinary Chemistry |
Dichlorotris(triphenylphosphine)ruthenium(II) is a coordination complex of ruthenium. It is a chocolate brown solid that is soluble in organic solvents such as benzene. The compound is used as a precursor to other complexes including those used in homogeneous catalysis. | 0 | Theoretical and Fundamental Chemistry |
Radon concentration in the atmosphere is usually measured in becquerels per cubic meter (Bq/m), which is an SI derived unit. As a frame of reference, typical domestic exposures are about 100 Bq/m indoors and 10–20 Bq/m outdoors. In the US, radon concentrations are often measured in picocuries per liter (pCi/L), with 1 pCi/L = 37 Bq/m.
The mining industry traditionally measures exposure using the working level (WL) index, and the cumulative exposure in working level months (WLM): 1 WL equals any combination of short-lived progeny (, , , and ) in 1 liter of air that releases 1.3 × 10 MeV of potential alpha energy; one WL is equivalent to 2.08 × 10 joules per cubic meter of air (J/m). The SI unit of cumulative exposure is expressed in joule-hours per cubic meter (J·h/m). One WLM is equivalent to 3.6 × 10 J·h/m. An exposure to 1 WL for 1 working month (170 hours) equals 1 WLM cumulative exposure.
A cumulative exposure of 1 WLM is roughly equivalent to living one year in an atmosphere with a radon concentration of 230 Bq/m.
The radon () released into the air decays to and other radioisotopes. The levels of can be measured. The rate of deposition of this radioisotope is dependent on the weather. | 1 | Applied and Interdisciplinary Chemistry |
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