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The bubble chamber was invented by Donald A. Glaser of the United States in 1952, and for this, he was awarded the Nobel Prize in Physics in 1960. The bubble chamber similarly reveals the tracks of subatomic particles, but as trails of bubbles in a superheated liquid, usually liquid hydrogen. Bubble chambers can be made physically larger than cloud chambers, and since they are filled with much-denser liquid material, they reveal the tracks of much more energetic particles. These factors rapidly made the bubble chamber the predominant particle detector for a number of decades, so that cloud chambers were effectively superseded in fundamental research by the start of the 1960s.
A spark chamber is an electrical device that uses a grid of uninsulated electric wires in a chamber, with high voltages applied between the wires. Energetic charged particles cause ionization of the gas along the path of the particle in the same way as in the Wilson cloud chamber, but in this case the ambient electric fields are high enough to precipitate full-scale gas breakdown in the form of sparks at the position of the initial ionization. The presence and location of these sparks is then registered electrically, and the information is stored for later analysis, such as by a digital computer.
Similar condensation effects can be observed as Wilson clouds, also called condensation clouds, at large explosions in humid air and other Prandtl–Glauert singularity effects. | 0 | Theoretical and Fundamental Chemistry |
In 1814, Jean-Jacques Colin discovered (to his surprise) that a mixture of dry gaseous ammonia and iodine formed a shiny, metallic-appearing liquid. Frederick Guthrie established the precise composition of the resulting I···NH complex fifty years later, but the physical processes underlying the molecular interaction remained mysterious until the development of Robert S. Mullikens theory of inner-sphere and outer-sphere interactions. In Mullikens categorization, the intermolecular interactions associated with small partial charges affect only the "inner sphere" of an atom's electron distribution; the electron redistribution associated with Lewis adducts affects the "outer sphere" instead.
Then, in 1954, Odd Hassel fruitfully applied the distinction to rationalize the X-ray diffraction patterns associated with a mixture of 1,4-dioxane and bromine. The patterns suggested that only 2.71 Å separated the dioxane oxygen atoms and bromine atoms, much closer than the sum (3.35 Å) of the atoms' van der Waals radii; and that the angle between the O−Br and Br−Br bond was about 180°. From these facts, Hassel concluded that halogen atoms are directly linked to electron pair donors in a direction with a bond direction that coincides with the axes of the orbitals of the lone pairs in the electron pair donor molecule. For this work, Hassel was awarded the 1969 Nobel Prize in Chemistry.
Dumas and coworkers first coined the term "halogen bond" in 1978, during their investigations into complexes of CCl, CBr, SiCl, and SiBr with tetrahydrofuran, tetrahydropyran, pyridine, anisole, and di-n-butyl ether in organic solvents.
However, it was not until the mid-1990s, that the nature and applications of the halogen bond began to be intensively studied. Through systematic and extensive microwave spectroscopy of gas-phase halogen bond adducts, Legon and coworkers drew attention to the similarities between halogen-bonding and better-known hydrogen-bonding interactions.
In 2007, computational calculations by Politzer and Murray showed that an anisotropic electron density distribution around the halogen nucleus — the "σ-hole" — underlay the high directionality of the halogen bond. This hole was then experimentally observed using Kelvin probe force microscopy.
In 2020, Kellett et al. showed that halogen bonds also have a π-covalent character similar to metal coordination bonds. In August 2023 the "π-hole" was too experimentally observed | 0 | Theoretical and Fundamental Chemistry |
Turbidity currents can result in internal hydraulic jumps (i.e., hydraulic jumps as internal waves in fluids of different density) in abyssal fan formation. The internal hydraulic jumps have been associated with salinity or temperature induced stratification as well as with density differences due to suspended materials. When the slope of the bed (over which the turbidity current flows) flattens, the slower rate of flow is mirrored by increased sediment deposition below the flow, producing a gradual backward slope. Where a hydraulic jump occurs, the signature is an abrupt backward slope, corresponding to the rapid reduction in the flow rate at the point of the jump. | 1 | Applied and Interdisciplinary Chemistry |
Here is a list of radioisotopes formed by the action of cosmic rays; the list also contains the production mode of the isotope. Most cosmogenic nuclides are formed in the atmosphere, but some are formed in situ in soil and rock exposed to cosmic rays, notably calcium-41 in the table below. | 0 | Theoretical and Fundamental Chemistry |
Optical depth of a material, denoted , is given by:where
* is the radiant flux received by that material;
* is the radiant flux transmitted by that material;
* is the transmittance of that material.
The absorbance is related to optical depth by: | 0 | Theoretical and Fundamental Chemistry |
Surrounding wildlife and fauna were drastically affected by Chernobyls explosions. Coniferous trees, which are plentiful in the surrounding landscape, were heavily affected due to their biological sensitivity to radiation exposure. Within days of the initial explosion many pine trees in a 4 km radius died, with lessening yet still harmful effects being observed up to 120 km away. Many trees experienced interruptions in their growth, reproduction was crippled, and there were multiple observations of morphological changes. Hot particles also landed on these forests, causing holes and hollows to be burned into the trees. The surrounding soil was covered in radionuclides, which prevented substantial new growth. Deciduous trees such as Aspen, Birch, Alder, and Oak trees are more resistant to radiation exposure than coniferous trees, however they arent immune. Damage seen on these trees was less harsh than observed on the pine trees. A lot of new deciduous growth suffered from necrosis, death of living tissue, and foliage on existing trees turned yellow and fell off. Deciduous trees resilience has allowed them to bounce back and they have populated where many coniferous trees, mostly pine, once stood. Herbaceous vegetation was also affected by radiation fallout. There were many observations of color changes in the cells, chlorophyll mutation, lack of flowering, growth depression, and vegetation death.
Mammals are a highly radio-sensitive class, and observations of mice in the surrounding area of Chernobyl showed a population decrease. Embryonic mortality increased as well, however, migration patterns of the rodents made the damaged population number increase once again. Among the small rodents affected, it was observed that there were increasing issues in the blood and livers, which is a direct correlation to radiation exposure. Issues such as liver cirrhosis, enlarged spleens, increased peroxide oxidation of tissue lipids, and a decrease in the levels of enzymes were all present in the rodents exposed to the radioactive blasts. Larger wildlife didn't fare much better. Although most livestock were relocated a safe distance away, horses and cattle located on an isolated island 6 km away from the Chernobyl radioactivity were not spared. Hyperthyroidism, stunted growth, and, of course, death plagued the animals left on the island.
The loss of human population in Chernobyl, sometimes referred to as the "exclusion zone," has allowed the ecosystems to recover. The use of herbicides, pesticides, and fertilizers has decreased because there is less agricultural activity. Biodiversity of plants and wildlife has increased, and animal populations have also increased. However, radiation continues to impact the local wildlife. | 0 | Theoretical and Fundamental Chemistry |
The fissile isotope uranium-235 in its natural concentration is unfit for the vast majority of nuclear reactors. In order to be prepared for use as fuel in energy production, it must be enriched. The enrichment process does not apply to plutonium. Reactor-grade plutonium is created as a byproduct of neutron interaction between two different isotopes of uranium. The first step to enriching uranium begins by converting uranium oxide (created through the uranium milling process) into a gaseous form. This gas is known as uranium hexafluoride, which is created by combining hydrogen fluoride, fluorine gas, and uranium oxide. Uranium dioxide is also present in this process and it is sent off to be used in reactors not requiring enriched fuel. The remaining uranium hexafluoride compound is drained into strong metal cylinders where it solidifies. The next step is separating the uranium hexafluoride from the depleted U-235 left over. This is typically done with centrifuges that spin fast enough to allow for the 1% mass difference in uranium isotopes to separate themselves. A laser is then used to enrich the hexafluoride compound. The final step involves reconverting the now enriched compound back into uranium oxide, leaving the final product: enriched uranium oxide. This form of UO can now be used in fission reactors inside power plants to produce energy. | 0 | Theoretical and Fundamental Chemistry |
Trace fossils provide us with indirect evidence of life in the past, such as the footprints, tracks, burrows, borings, and feces left behind by animals, rather than the preserved remains of the body of the actual animal itself. Unlike most other fossils, which are produced only after the death of the organism concerned, trace fossils provide us with a record of the activity of an organism during its lifetime.
Trace fossils are formed by organisms performing the functions of their everyday life, such as walking, crawling, burrowing, boring, or feeding. Tetrapod footprints, worm trails and the burrows made by clams and arthropods are all trace fossils.
Perhaps the most spectacular trace fossils are the huge, three-toed footprints produced by dinosaurs and related archosaurs. These imprints give scientists clues as to how these animals lived. Although the skeletons of dinosaurs can be reconstructed, only their fossilized footprints can determine exactly how they stood and walked. Such tracks can tell much about the gait of the animal which made them, what its stride was, and whether the front limbs touched the ground or not.
However, most trace fossils are rather less conspicuous, such as the trails made by segmented worms or nematodes. Some of these worm castings are the only fossil record we have of these soft-bodied creatures. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a halogen bond (XB) occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. Like a hydrogen bond, the result is not a formal chemical bond, but rather a strong electrostatic attraction. Mathematically, the interaction can be decomposed in two terms: one describing an electrostatic, orbital-mixing charge-transfer and another describing electron-cloud dispersion. Halogen bonds find application in supramolecular chemistry; drug design and biochemistry; crystal engineering and liquid crystals; and organic catalysis. | 0 | Theoretical and Fundamental Chemistry |
By immobilizing proteins to polymer nanoparticles or polymer/inorganic hybrid nanoparticles (such as polymer-stabilized iron oxide nanoparticles), proteins or their affinity ligands can be separated from complex solutions by applying magnetic fields or centrifugation. Lipase attached to iron oxide nanoparticles maintained 85% biological activity after 30 reaction and separation cycles.
As the appropriate target is combined with magnetic nanoparticles, the selected target can be magnetically separated directly from natural biological fluids, which offers a fast, gentle, extensible, and easy to automate separation technique. The simplicity of magnetic separation has been applied in a number of disciplines, including mineral processing wastewater treatment, molecular biology, cell sorting, and clinical diagnostics. | 1 | Applied and Interdisciplinary Chemistry |
* Cryobiology, the branch of biology that studies the effects of low temperatures on living things
* Cryonics, the low-temperature preservation of people who cannot be sustained by contemporary medicine
* Cryoprecipitate, a blood-derived protein product used to treat some bleeding disorders
* Cryotherapy, medical treatment using cold
** Cryoablation, tissue removal using cold
** Cryosurgery, surgery using cold
* Cryo-electron microscopy (cryoEM), a technique that fires beams of electrons at proteins that have been frozen in solution, to deduce the biomolecules’ structure | 1 | Applied and Interdisciplinary Chemistry |
The regulation of genetic engineering concerns the approaches taken by governments to assess and manage the risks associated with the development and release of genetically modified crops. There are differences in the regulation of GM crops – including those used for pharming – between countries, with some of the most marked differences occurring between the USA and Europe. Regulation varies in a given country depending on the intended use of the products of the genetic engineering. For example, a crop not intended for food use is generally not reviewed by authorities responsible for food safety. | 1 | Applied and Interdisciplinary Chemistry |
Some radioactive iodide salts of sodium, including NaI and NaI, have radiopharmaceutical uses for thyroid cancer and hyperthyroidism or as radioactive tracer in imaging (see Isotopes of iodine > Radioiodines I-123, I-124, I-125, and I-131 in medicine and biology). | 0 | Theoretical and Fundamental Chemistry |
The Knudsen number is a dimensionless number defined as
where
: = mean free path [L],
: = representative physical length scale [L].
The representative length scale considered, , may correspond to various physical traits of a system, but most commonly relates to a gap length over which thermal transport or mass transport occurs through a gas phase. This is the case in porous and granular materials, where the thermal transport through a gas phase depends highly on its pressure and the consequent mean free path of molecules in this phase. For a Boltzmann gas, the mean free path may be readily calculated, so that
where
: is the Boltzmann constant (1.380649 × 10 J/K in SI units) [M L T Θ],
: is the thermodynamic temperature [θ],
: is the particle hard-shell diameter [L],
: is the static pressure [M L T],
: is the specific gas constant [L T θ] (287.05 J/(kg K) for air),
: is the density [M L].
If the temperature is increased, but the volume kept constant, then the Knudsen number (and the mean free path) doesnt change (for an ideal gas). In this case, the density stays the same. If the temperature is increased, and the pressure' kept constant, then the gas expands and therefore its density decreases. In this case, the mean free path increases and so does the Knudsen number. Hence, it may be helpful to keep in mind that the mean free path (and therefore the Knudsen number) is really dependent on the thermodynamic variable density (proportional to the reciprocal of density), and only indirectly on temperature and pressure.
For particle dynamics in the atmosphere, and assuming standard temperature and pressure, i.e. 0 °C and 1 atm, we have ≈ (80 nm). | 1 | Applied and Interdisciplinary Chemistry |
Preparing TNP-ATP is a one-step synthesis that is relatively safe and easy. Adenosine’s ribose moiety can be trinitrophenylated by 2,4,6-trinitrobenzene-1-sulfonate (TNBS). The resulting compound assumes a bright orange color and has visible absorption characteristics, as is characteristic of a Meiseinheimer spiro complex compound linking.
To see the exact method of preparion, please refer to T. Hiratsukas and K. Uchidas paper "Preparation and Properties of 2(r 3)-O(2,4,6-trinitrophenyl) Adenosine 5-triphosphate, an Analog of Adenosine Triphosphate,"' found in the reference section.
To revert TNP-ATP back to its constituent parts, or in other words to hydrolyze TNP-ATP to give equilmolar amounts of picric acid (TNP) and ATP, TNP-ATP should be treated with 1 M HCl at 100 degrees Celsius for 1.5 hours. This is because if TNP-ATP is acidified under mild conditions, it results in the opening of the dioxolane ring attached to the 2’-oxygen, leaving a 3’O-TNP derivative as the only product. | 0 | Theoretical and Fundamental Chemistry |
In a 2012 University of Amsterdam study of 120 women, women's luteal phase (higher levels of progesterone, and increasing levels of estrogen) was correlated with lower level of competitive behavior in gambling and math contest scenarios, while their premenstrual phase (sharply-decreasing levels of progesterone, and decreasing levels of estrogen) was correlated with a higher level of competitive behavior. | 0 | Theoretical and Fundamental Chemistry |
The Hammett acidity function (H) is a measure of acidity that is used for very concentrated solutions of strong acids, including superacids. It was proposed by the physical organic chemist Louis Plack Hammett and is the best-known acidity function used to extend the measure of Brønsted–Lowry acidity beyond the dilute aqueous solutions for which the pH scale is useful.
In highly concentrated solutions, simple approximations such as the Henderson–Hasselbalch equation are no longer valid due to the variations of the activity coefficients. The Hammett acidity function is used in fields such as physical organic chemistry for the study of acid-catalyzed reactions, because some of these reactions use acids in very high concentrations, or even neat (pure). | 0 | Theoretical and Fundamental Chemistry |
An Ion Gun typically refers to an instrument that generates a beam of heavy ions with a well defined energy distribution. The ion beam is produced from a plasma that has been confined within a volume. Ions of a particular energy are extracted, accelerated, collimated and/or focused. The ion gun is composed of an ion source, extraction grid structure and a collimation/lensing structure. The plasma can be made up of an inert or reactive gas (e.g. N and O) or an easily condensable substance (e.g. C and B). The plasma can be formed from molecules that contain the substance which will form the beam, in which case, these molecules must be fragmented then ionized (e.g. H and CH can together be fragmented and ionized to create a beam for depositing diamond-like carbon films).
The ion current density (or similarly the ion flux), the ion energy spread, and the resolution of the ion beam are key factors in ion gun design. The ion current density is controlled by the ion source, the energy spread is determined primarily by the extraction grid, and the resolution is determined primarily by the optical column.
The ion gun is an important component in surface science in that it provides the scientist with a means to sputter etch a surface and generate an elemental or chemical depth profile. Modern ion guns can produce beam energies from 10eV to more than 10keV. | 0 | Theoretical and Fundamental Chemistry |
The formation of Langmuir monolayers by adsorption onto a surface dramatically reduces the entropy of the molecular system.
To find the entropy decrease, we find the entropy of the molecule when in the adsorbed condition.
Using Stirling's approximation, we have
On the other hand, the entropy of a molecule of an ideal gas is
where is the thermal de Broglie wavelength of the gas molecule. | 0 | Theoretical and Fundamental Chemistry |
A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary photosynthetic tissue is the palisade mesophyll and is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus, palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper (adaxial) and lower (abaxial) surfaces that differ in color, hairiness, the number of stomata (pores that intake and output gases), the amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to the presence of a compound called chlorophyll which is essential for photosynthesis as it absorbs light energy from the sun. A leaf with lighter-colored or white patches or edges is called a variegated leaf.
Leaves can have many different shapes, sizes, textures and colors. The broad, flat leaves with complex venation of flowering plants are known as megaphylls and the species that bear them, the majority, as broad-leaved or megaphyllous plants, which also include acrogymnosperms and ferns. In the lycopods, with different evolutionary origins, the leaves are simple (with only a single vein) and are known as microphylls. Some leaves, such as bulb scales, are not above ground. In many aquatic species, the leaves are submerged in water. Succulent plants often have thick juicy leaves, but some leaves are without major photosynthetic function and may be dead at maturity, as in some cataphylls and spines. Furthermore, several kinds of leaf-like structures found in vascular plants are not totally homologous with them. Examples include flattened plant stems called phylloclades and cladodes, and flattened leaf stems called phyllodes which differ from leaves both in their structure and origin. Some structures of non-vascular plants look and function much like leaves. Examples include the phyllids of mosses and liverworts. | 0 | Theoretical and Fundamental Chemistry |
The term episome was introduced by François Jacob and Élie Wollman in 1958 to refer to extra-chromosomal genetic material that may replicate autonomously or become integrated into the chromosome. Since the term was introduced, however, its use has changed, as plasmid has become the preferred term for autonomously replicating extrachromosomal DNA. At a 1968 symposium in London some participants suggested that the term episome be abandoned, although others continued to use the term with a shift in meaning.
Today, some authors use episome in the context of prokaryotes to refer to a plasmid that is capable of integrating into the chromosome. The integrative plasmids may be replicated and stably maintained in a cell through multiple generations, but at some stage, they will exist as an independent plasmid molecule. In the context of eukaryotes, the term episome is used to mean a non-integrated extrachromosomal closed circular DNA molecule that may be replicated in the nucleus. Viruses are the most common examples of this, such as herpesviruses, adenoviruses, and polyomaviruses, but some are plasmids. Other examples include aberrant chromosomal fragments, such as double minute chromosomes, that can arise during artificial gene amplifications or in pathologic processes (e.g., cancer cell transformation). Episomes in eukaryotes behave similarly to plasmids in prokaryotes in that the DNA is stably maintained and replicated with the host cell. Cytoplasmic viral episomes (as in poxvirus infections) can also occur. Some episomes, such as herpesviruses, replicate in a rolling circle mechanism, similar to bacteriophages (bacterial phage viruses). Others replicate through a bidirectional replication mechanism (Theta type plasmids). In either case, episomes remain physically separate from host cell chromosomes. Several cancer viruses, including Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus, are maintained as latent, chromosomally distinct episomes in cancer cells, where the viruses express oncogenes that promote cancer cell proliferation. In cancers, these episomes passively replicate together with host chromosomes when the cell divides. When these viral episomes initiate lytic replication to generate multiple virus particles, they generally activate cellular innate immunity defense mechanisms that kill the host cell. | 1 | Applied and Interdisciplinary Chemistry |
:DNA strand 1: antisense strand (transcribed to) → RNA strand (sense)
:DNA strand 2: sense strand
Some regions within a double-stranded DNA molecule code for genes, which are usually instructions specifying the order in which amino acids are assembled to make proteins, as well as regulatory sequences, splicing sites, non-coding introns, and other gene products. For a cell to use this information, one strand of the DNA serves as a template for the synthesis of a complementary strand of RNA. The transcribed DNA strand is called the template strand, with antisense sequence, and the mRNA transcript produced from it is said to be sense sequence (the complement of antisense). The untranscribed DNA strand, complementary to the transcribed strand, is also said to have sense sequence; it has the same sense sequence as the mRNA transcript (though T bases in DNA are substituted with U bases in RNA).
The names assigned to each strand actually depend on which direction you are writing the sequence that contains the information for proteins (the "sense" information), not on which strand is depicted as "on the top" or "on the bottom" (which is arbitrary). The only biological information that is important for labeling strands is the relative locations of the terminal 5′ phosphate group and the terminal 3′ hydroxyl group (at the ends of the strand or sequence in question), because these ends determine the direction of transcription and translation. A sequence written 5′-CGCTAT-3′ is equivalent to a sequence written 3′-TATCGC-5′ as long as the 5′ and 3′ ends are noted. If the ends are not labeled, convention is to assume that both sequences are written in the 5′-to-3′ direction. The "Watson strand" refers to 5′-to-3′ top strand (5′→3′), whereas the "Crick strand" refers to the 5′-to-3′ bottom strand (3′←5′). Both Watson and Crick strands can be either sense or antisense strands depending on the specific gene product made from them.
For example, the notation "YEL021W", an alias of the URA3 gene used in the National Center for Biotechnology Information (NCBI) database, denotes that this gene is in the 21st open reading frame (ORF) from the centromere of the left arm (L) of Yeast (Y) chromosome number V (E), and that the expression coding strand is the Watson strand (W). "YKL074C" denotes the 74th ORF to the left of the centromere of chromosome XI and that the coding strand is the Crick strand (C). Another confusing term referring to "Plus" and "Minus" strand is also widely used. Whether the strand is sense (positive) or antisense (negative), the default query sequence in NCBI BLAST alignment is "Plus" strand. | 1 | Applied and Interdisciplinary Chemistry |
A primary kinetic isotope effect may be found when a bond to the isotopically labeled atom is being formed or broken. Depending on the way a kinetic isotope effect is probed (parallel measurement of rates vs. intermolecular competition vs. intramolecular competition), the observation of a primary kinetic isotope effect is indicative of breaking/forming a bond to the isotope at the rate-limiting step, or subsequent product-determining step(s). (The misconception that a primary kinetic isotope effect must reflect bond cleavage/formation to the isotope at the rate-limiting step is frequently repeated in textbooks and the primary literature: see the section on experiments below.)
For the previously mentioned nucleophilic substitution reactions, primary kinetic isotope effects have been investigated for both the leaving groups, the nucleophiles, and the α-carbon at which the substitution occurs. Interpretation of the leaving group kinetic isotope effects had been difficult at first due to significant contributions from temperature independent factors. Kinetic isotope effects at the α-carbon can be used to develop some understanding into the symmetry of the transition state in S2 reactions, although this kinetic isotope effect is less sensitive than what would be ideal, also due to contribution from non-vibrational factors. | 0 | Theoretical and Fundamental Chemistry |
Air pumps, such as the roots blower, use meshing impellers to move air through a system. Applications include blast furnaces, ventilation systems, and superchargers for internal combustion engines. | 1 | Applied and Interdisciplinary Chemistry |
Ceftezole (or ceftezol) is a semisynthetic first-generation cephalosporin antibiotic.
Ceftezole binds to and inactivates penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. PBPs are enzymes involved in the terminal stages of assembling the bacterial cell wall and in reshaping the cell wall during growth and division. Inactivation of PBPs interferes with the cross-linkage of peptidoglycan chains necessary for bacterial cell wall strength and rigidity. This results in the weakening of the bacterial cell wall and causes cell lysis.
Ceftezole is having (1,3,4-thiadiazol-2-ylsulfanyl)methyl and [2-(1H-tetrazol-1-yl)acetamido side groups located at positions 3 and 7 respectively. It is a cephalosporin and a member of thiadiazoles. | 0 | Theoretical and Fundamental Chemistry |
Research in different areas mention possible use cases of EPIC-seq. Integrated analysis toolkit for whole-genome-wide features of cfDNA (INAC) compiles different tools, including EPIC-seq's PFE and NDR scores, to provide in comprehensive silico analysis of cfDNA which can be exemplified disease state and clinical outcome inference, transcriptome modeling, and copy number profiling. EPIC-seq is also mentioned to be a potential application in clinica IBD cases. It can be used for survailance of IBD in high-risk groups and precancerous development caused by IBD. It is also named as a possible superior method in clinical IBD gut damage detection, compared to the current methods. | 1 | Applied and Interdisciplinary Chemistry |
In the ongoing "Omhoog met het Veen - AddMire in the Netherlands" research project, Landscape Noord-Holland aims to investigate the restoration of reed beds and wet heathlands on moors previously converted for agriculture as well as to raise awareness about peatland degradation. The project is intended to promote paludiculture as an alternative income from agriculture. Researchers have rewetted 8 hectares, including for a water storage buffer area for the peat moss experiments. They are measuring the effects of soil erosion and atmospheric nitrogen on the growth of peat moss and the resulting greenhouse gas emissions and soil chemistry. | 1 | Applied and Interdisciplinary Chemistry |
The term pewter covers a variety of alloys consisting primarily of tin. As a pure metal, tin is much too soft to use for most practical purposes. However, during the Bronze Age, tin was a rare metal in many parts of Europe and the Mediterranean, so it was often valued higher than gold. To make jewellery, cutlery, or other objects from tin, workers usually alloyed it with other metals to increase strength and hardness. These metals were typically lead, antimony, bismuth or copper. These solutes were sometimes added individually in varying amounts, or added together, making a wide variety of objects, ranging from practical items such as dishes, surgical tools, candlesticks or funnels, to decorative items like ear rings and hair clips.
The earliest examples of pewter come from ancient Egypt, around 1450 BC. The use of pewter was widespread across Europe, from France to Norway and Britain (where most of the ancient tin was mined) to the Near East. The alloy was also used in China and the Far East, arriving in Japan around 800 AD, where it was used for making objects like ceremonial vessels, tea canisters, or chalices used in shinto shrines. | 1 | Applied and Interdisciplinary Chemistry |
* Full-length ncRNA capture – BoMoC has high processivity across modified RNA templates resulting in the production of more full-length cDNA products compared to common reverse transcriptase's, which are prone to premature termination at modified sites.
* Single tube reaction – All cDNA synthesis steps can be performed in a single tube, without the need for intermediate purification steps. This allows for automation of the OTTR approach. Additionally, this reduces the total amount of input RNA required purification steps, prone to loss of
* Capture of modified sites – Mis-incorporation signatures of BoMoC across modified RNA bases have been characterized. Therefore, OTTR allows for the identification of modification status of RNA transcripts where modified sites are known.
* Sequencing of both RNA and DNA templates – While RNA templates have been used to benchmark the OTTR technique, BoMoC is processive over DNA, meaning this library preparation approach could be adapted for DNA characterization. | 1 | Applied and Interdisciplinary Chemistry |
ILAC describes the following five types of reference material:
# Pure substances; essentially pure chemicals, characterised for chemical purity and/or trace impurities.
# Standard solutions and gas mixtures, often prepared gravimetrically from pure substances.
# Matrix reference materials, characterised for the composition of specified major, minor or trace chemical constituents. Such materials may be prepared from matrices containing the components of interest, or by preparing synthetic mixtures.
# Physico-chemical reference materials, characterised for properties such as melting point, viscosity, or optical density.
# Reference objects or artifacts, characterised for functional properties such as taste, odour, octane number, flash point and hardness. This type also includes microscopy specimens characterised for properties ranging from fibre type to microbiological specimens. | 0 | Theoretical and Fundamental Chemistry |
A sequence contig is a continuous (not contiguous) sequence resulting from the reassembly of the small DNA fragments generated by bottom-up sequencing strategies. This meaning of contig is consistent with the original definition by Rodger Staden (1979). The bottom-up DNA sequencing strategy involves shearing genomic DNA into many small fragments ("bottom"), sequencing these fragments, reassembling them back into contigs and eventually the entire genome ("up"). Because current technology allows for the direct sequencing of only relatively short DNA fragments (300–1000 nucleotides), genomic DNA must be fragmented into small pieces prior to sequencing. In bottom-up sequencing projects, amplified DNA is sheared randomly into fragments appropriately sized for sequencing. The subsequent sequence reads, which are the data that contain the sequences of the small fragments, are put into a database. The assembly software then searches this database for pairs of overlapping reads. Assembling the reads from such a pair (including, of course, only one copy of the identical sequence) produces a longer contiguous read (contig) of sequenced DNA. By repeating this process many times, at first with the initial short pairs of reads but then using increasingly longer pairs that are the result of previous assembly, the DNA sequence of an entire chromosome can be determined.
Today, it is common to use paired-end sequencing technology where both ends of consistently sized longer DNA fragments are sequenced. Here, a contig still refers to any contiguous stretch of sequence data created by read overlap. Because the fragments are of known length, the distance between the two end reads from each fragment is known. This gives additional information about the orientation of contigs constructed from these reads and allows for their assembly into scaffolds in a process called scaffolding.
Scaffolds consist of overlapping contigs separated by gaps of known length. The new constraints placed on the orientation of the contigs allows for the placement of highly repeated sequences in the genome. If one end read has a repetitive sequence, as long as its mate pair is located within a contig, its placement is known. The remaining gaps between the contigs in the scaffolds can then be sequenced by a variety of methods, including PCR amplification followed by sequencing (for smaller gaps) and BAC cloning methods followed by sequencing for larger gaps. | 1 | Applied and Interdisciplinary Chemistry |
Blue, white and ultraviolet LEDs are grown on industrial scale by MOVPE. The precursors are ammonia with either trimethylgallium or triethylgallium, the carrier gas being nitrogen or hydrogen. Growth temperature ranges between . Introduction of trimethylaluminium and/or trimethylindium is necessary for growing quantum wells and other kinds of heterostructures. | 0 | Theoretical and Fundamental Chemistry |
Shrinkage defects
can occur when standard feed metal is not available to compensate for shrinkage as the thick metal solidifies. Shrinkage defects will have jagged or linear appearance. Shrinkage defects usually occur in either the cope or drag portion of the casting. Shrinkage defects can be split into two different types: open shrinkage defects and closed shrinkage defects. Open shrinkage defects are open to the atmosphere, therefore as the shrinkage cavity forms, air compensates. There are two types of open air defects: pipes and caved surfaces. Pipes form at the surface of the casting and burrow into the casting, while caved surfaces are shallow cavities that form across the surface of the casting.
Closed shrinkage defects, also known as shrinkage porosity, are defects that form within the casting. Isolated pools of liquid form inside solidified metal, which are called hot spots. The shrinkage defect usually forms at the top of the hot spots. They require a nucleation point, so impurities and dissolved gas can induce closed shrinkage defects. The defects are broken up into macroporosity and microporosity (or micro shrinkage), where macroporosity can be seen by the naked eye and microporosity cannot. | 1 | Applied and Interdisciplinary Chemistry |
Statistics Canada administers the Canadian Health Measures Survey, which includes biomonitoring for environmental chemicals. Health Canada administers a program called Mother-Infant Research on Environmental Chemicals, which focuses on 2,000 pregnant women and their infants. | 1 | Applied and Interdisciplinary Chemistry |
Solvent extraction is used to extract individual lanthanoid elements from the mixtures found in nature in ores such as monazite. In one process, the metal ions in aqueous solution are made to form complexes with tributylphosphate (TBP), which are extracted into an organic solvent such as kerosene. Complete separation is effected by using a countercurrent exchange method. A number of cells are arranged as a cascade. After equilibration, the aqueous component of each cell is transferred to the previous cell and the organic component is transferred to the next cell, which initially contains only water. In this way the metal ion with the most stable complex passes down the cascade in the organic phase and the metal with the least stable complex passes up the cascade in the aqueous phase.
If solubility in the organic phase is not an issue, a selectivity coefficient is equal to the ratio of the stability constants of the TBP complexes of two metal ions. For lanthanoid elements which are adjacent in the periodic table this ratio is not much greater than 1, so many cells are needed in the cascade. | 0 | Theoretical and Fundamental Chemistry |
The story is often told of Napoleons men freezing in the bitter Russian Winter, their clothes falling apart as tin pest ate the buttons. This appears to be an urban legend, as there is no evidence of any failing buttons, and thus they cannot have been a contributing factor in the failure of the invasion. Uniform buttons of that era were generally bone for enlisted, and brass for officers. Critics of the theory point out that any tin that might have been used would have been quite impure, and thus more tolerant of low temperatures. Laboratory tests of the time required for unalloyed tin to develop significant tin pest damage at lowered temperatures is about 18 months, which is more than twice the length of the invasion. Nevertheless, some of the regiments in the campaign did have tin buttons and the temperature reached sufficiently low values (below −40 °C or °F). In the event, none of the many survivors tales mention problems with buttons and it has been suggested that the legend is an amalgamation of reports of blocks of Banca tin completely disintegrated in a customs warehouse in St. Petersburg in 1868, and earlier Russian reports that cast-in buttons for military uniforms also disintegrated, and the desperate state of Napoleon's army, having turned soldiers into ragged beggars. | 1 | Applied and Interdisciplinary Chemistry |
* Carnegie Library of Pittsburgh. Science and Technology Department. The Handy Science Answer Book. Pittsburgh: The Carnegie Library, 1997. .
* Taylor, L., and S. Oberman. Drunk Driving Defense, 6th edition. New York: Aspen Law and Business, 2006. . | 1 | Applied and Interdisciplinary Chemistry |
Some viruses (such as HIV, the cause of AIDS), have the ability to transcribe RNA into DNA. HIV has an RNA genome that is reverse transcribed into DNA. The resulting DNA can be merged with the DNA genome of the host cell. The main enzyme responsible for synthesis of DNA from an RNA template is called reverse transcriptase.
In the case of HIV, reverse transcriptase is responsible for synthesizing a complementary DNA strand (cDNA) to the viral RNA genome. The enzyme ribonuclease H then digests the RNA strand, and reverse transcriptase synthesises a complementary strand of DNA to form a double helix DNA structure (cDNA). The cDNA is integrated into the host cell's genome by the enzyme integrase, which causes the host cell to generate viral proteins that reassemble into new viral particles. In HIV, subsequent to this, the host cell undergoes programmed cell death, or apoptosis, of T cells. However, in other retroviruses, the host cell remains intact as the virus buds out of the cell.
Some eukaryotic cells contain an enzyme with reverse transcription activity called telomerase. Telomerase carries an RNA template from which it synthesizes a telomere, a repeating sequence of DNA, to the end of linear chromosomes. It is important because every time a linear chromosome is duplicated, it is shortened. With the telomere at the ends of chromosomes, the shortening eliminates some of the non-essential, repeated sequence, rather than the protein-encoding DNA sequence farther away from the chromosome end.
Telomerase is often activated in cancer cells to enable cancer cells to duplicate their genomes indefinitely without losing important protein-coding DNA sequence. Activation of telomerase could be part of the process that allows cancer cells to become immortal. The immortalizing factor of cancer via telomere lengthening due to telomerase has been proven to occur in 90% of all carcinogenic tumors in vivo with the remaining 10% using an alternative telomere maintenance route called ALT or Alternative Lengthening of Telomeres. | 1 | Applied and Interdisciplinary Chemistry |
The configuration index consists of two digits which are the priority numbers of the ligands on the threefold rotation axis. The lowest numerical value is cited first. | 0 | Theoretical and Fundamental Chemistry |
One of the challenges in generating in vivo like cultures or tissue in vitro is the difficulty in co-culturing different cell types. Because of the ability of 3D cell culturing by magnetic levitation to bring cells together, co-culturing different cell types is possible. Co-culturing of different cell types can be achieved at the onset of levitation, by mixing different cell types in before levitation or by magnetically guiding 3D cultures in an invasion assay format.
The unique ability to manipulate cells and shape tissue magnetically offers new possibilities for controlled co-culturing and invasion assays. Co-culturing in a realistic tissue architecture is critical for accurately modeling in vivo conditions, such as for increasing the accuracy of cellular assays as shown in the figure below.
Shown in the picture above is an invasion assay of magnetically levitated multicellular spheroids; fluorescence images of human glioblastoma (GBM) cells (green; GFP-expressing cells) and normal human astrocytes (NHA) (red; mCherry-labelled) cultured separately and then magnetically guided together (left, time 0). Invasion of GBM into NHA in 3D culture provides a powerful new assay for basic cancer biology and drug screening (right, 12h to 252h). | 0 | Theoretical and Fundamental Chemistry |
* Loupe (sidérurgie)
* Krupp-Renn Process
* Direct reduced iron.
* Direct reduction (blast furnace)
* Histoire de la production de l'acier. | 1 | Applied and Interdisciplinary Chemistry |
A generalized compound is a mixture of chemical compounds of constant composition, despite possible changes in the total amount. The concept is used in the Dynamic Energy Budget theory, where biomass is partitioned into a limited set of generalised compounds, which contain a high percentage of organic compounds. The amount of generalized compound can be quantified in terms of weight, but more conveniently in terms of C-moles. The concept of strong homeostasis has an intimate relationship with that of generalised compound. | 1 | Applied and Interdisciplinary Chemistry |
The purpose of a mineralizer is to facilitate the transport of insoluble “nutrient” to a seed crystal by means of a reversible chemical reaction. Over time, the seed crystal accumulates the material that was once in the nutrient and grows. Mineralizers are additives that aid the solubilization of the nutrient solid. When used in small quantities, mineralizers function as catalysts. Typically, a more stable solid is crystallized from a solution that consists of a less stable solid and a solvent. The process is done by dissolution-precipitation or crystallization process.
Hydrothermal growth involves the crystallization of a dissolved solid at elevated temperatures. Often high pressures are involved. Historically, the goal of hydrothermal growth was to grow large crystals. Due to the recent developments in nanotechnology, small nanocrystals are now desired and made by hydrothermal growth with crystal size controlled by mineralizers. Different mineralizers result in crystals of different sizes and shapes. Typical mineralizers are hydroxides (NaOH, KOH, LiOH), carbonates (NaCO) and halides (NaF, KF, LiF, NaCl, KCl, LiCl). | 0 | Theoretical and Fundamental Chemistry |
For a sudden expansion in a pipe, see the figure above, the Borda–Carnot equation can be derived from mass- and momentum conservation of the flow. The momentum flux S (i.e. for the fluid momentum component parallel to the pipe axis) through a cross section of area A is – according to the Euler equations:
Consider the conservation of mass and momentum for a control volume bounded by cross section 1 just upstream of the expansion, cross section 2 downstream of where the flow re-attaches again to the pipe wall (after the flow separation at the expansion), and the pipe wall. There is the control volumes gain of momentum S at the inflow and loss S at the outflow. Besides, there is also the contribution of the force F by the pressure on the fluid exerted by the expansions wall (perpendicular to the pipe axis):
where it has been assumed that the pressure is equal to the close-by upstream pressure p.
Adding contributions, the momentum balance for the control volume between cross sections 1 and 2 gives:
Consequently, since by mass conservation :
in agreement with the pressure drop Δp in the example above.
The mechanical energy loss ΔE is:
which is the Borda–Carnot equation (with ξ = 1). | 1 | Applied and Interdisciplinary Chemistry |
; Main textbook
* – A molecular biology textbook available free online through NCBI Bookshelf.
:[https://www.ncbi.nlm.nih.gov/books/NBK21052/ Glossary]
:[https://www.ncbi.nlm.nih.gov/books/NBK26864/ Ch 1: Cells and genomes]
::[https://www.ncbi.nlm.nih.gov/books/NBK26864/ 1.1: The Universal Features of Cells on Earth]
:[https://www.ncbi.nlm.nih.gov/books/NBK21068/ Ch 2: Cell Chemistry and Biosynthesis]
::[https://www.ncbi.nlm.nih.gov/books/NBK26883/ 2.1: The Chemical Components of a Cell]
:[https://www.ncbi.nlm.nih.gov/books/NBK26830/ Ch 3: Proteins]
:[https://www.ncbi.nlm.nih.gov/books/NBK21074/ Ch 4: DNA and Chromosomes]
::[https://www.ncbi.nlm.nih.gov/books/NBK26821/ 4.1: The Structure and Function of DNA]
::[https://www.ncbi.nlm.nih.gov/books/NBK26834/ 4.2: Chromosomal DNA and Its Packaging in the Chromatin Fiber]
:[https://www.ncbi.nlm.nih.gov/books/NBK21064/ Ch 5: DNA Replication, Repair, and Recombination]
::[https://www.ncbi.nlm.nih.gov/books/NBK26850/ 5.2: DNA Replication Mechanisms]
::[https://www.ncbi.nlm.nih.gov/books/NBK26879/ 5.4: DNA Repair]
::[https://www.ncbi.nlm.nih.gov/books/NBK26898/ 5.5: General Recombination]
:[https://www.ncbi.nlm.nih.gov/books/NBK21050/ Ch 6: How Cells Read the Genome: From DNA to Protein]
::[https://www.ncbi.nlm.nih.gov/books/NBK26887/ 6.1: DNA to RNA]
::[https://www.ncbi.nlm.nih.gov/books/NBK26829/ 6.2: RNA to Protein]
:[https://www.ncbi.nlm.nih.gov/books/NBK21057/ Ch 7: Control of Gene Expression]
::[https://www.ncbi.nlm.nih.gov/books/NBK26885/ 7.1: An Overview of Gene Control]
::[https://www.ncbi.nlm.nih.gov/books/NBK26806/ 7.2: DNA-Binding Motifs in Gene Regulatory Proteins]
::[https://www.ncbi.nlm.nih.gov/books/NBK26872/ 7.3: How Genetic Switches Work]
::[https://www.ncbi.nlm.nih.gov/books/NBK26890/ 7.5: Posttranscriptional Controls]
::[https://www.ncbi.nlm.nih.gov/books/NBK26836/ 7.6: How Genomes Evolve]
:[https://www.ncbi.nlm.nih.gov/books/NBK21063/ Ch 14: Energy Conversion: Mitochondria and Chloroplasts]
::[https://www.ncbi.nlm.nih.gov/books/NBK26924/ 14.4: The Genetic Systems of Mitochondria and Plastids]
:[https://www.ncbi.nlm.nih.gov/books/NBK21065/ Ch 18: The Mechanics of Cell Division]
::[https://www.ncbi.nlm.nih.gov/books/NBK26931/ 18.1: An Overview of M Phase]
::[https://www.ncbi.nlm.nih.gov/books/NBK26934/ 18.2: Mitosis]
:[https://www.ncbi.nlm.nih.gov/books/NBK21049/ Ch 20: Germ Cells and Fertilization]
::[https://www.ncbi.nlm.nih.gov/books/NBK26840/ 20.2: Meiosis] | 1 | Applied and Interdisciplinary Chemistry |
Modafinil was considered for the treatment of ADHD because of its lower abuse potential than conventional psychostimulants like methylphenidate and amphetamines. In 2008, an application to market modafinil for pediatric ADHD was submitted to the Food and Drug Administration in the US.
However, evidence of modafinil for treatment of adult ADHD is mixed, and a 2016 systematic review of alternative drug therapies for adult ADHD did not recommend its use in this context. In a later large phase 3 clinical trial of modafinil for adult ADHD, modafinil was not effective in improving symptoms, and there was a high rate of side effects (86%) and discontinuation (47%). The poor tolerability of modafinil in this study was possibly due to the use of high doses (). Another reason for the denial of the approval was due to concerns about rare but serious dermatological toxicity in Stevens–Johnson syndrome). | 0 | Theoretical and Fundamental Chemistry |
There is political dispute between China and South Korea on ultrafine dust. South Korea claims that about 80% of ultrafine dust comes from China, and China and South Korea should cooperate to reduce the level of fine dust. China, however, argues that the Chinese government have already implemented its policy regarding ecological environment. According to China's government, its quality of air has been improved more than 40% since 2013. However, the air pollution in South Korea got worse. Therefore, the dispute between China and South Korea has become political. In March 2019, Seoul Research Institute of Public Health and Environment said that 50% to 70% of the fine dust is from China, therefore China is responsible for the air pollution in South Korea. This dispute provokes dispute among citizens as well.
In July 2014, China's paramount leader Xi Jinping and the South Korean government agreed to enforce Korea-China Cooperative Project, regarding Sharing of observation data on air pollutions, joint research on an air pollution forecast model and air pollution source identification, and human resources exchanges, etc. Followed by this agreement, in 2018, China and South Korea signed China-Korea Environmental Cooperation Plan to resolute environmental issues. China Research Academy of Environmental Studies (CRAES) in Beijing is developing a building for China-Korea Environmental Cooperation Center including office building and laboratory building. Based on this cooperation, South Korea already sent 10 experts on environments to China for research, and China will also send more experts for long-term research. By this bilateral relations, China and Republic of Korea are seeking resolution on air pollution in North East Asia region, and seeks international security. | 0 | Theoretical and Fundamental Chemistry |
An aqueous solution of cobalt(II) nitrate and hydrogen peroxide is added to a solution of sodium bicarbonate, leading to precipitation of the olive solid. The method is a modification of the synthesis of what has been described as “Co(CO)”. | 0 | Theoretical and Fundamental Chemistry |
The mechanism of electromethanogenesis is outlined in Figure 1. Water is introduced into the system with the anode, biocathode, and microbes. At the anode, microbes attract HO molecules which are then oxidized after an electrical current is turned on from the power source. Oxygen is released from the anode side. The protons and electrons oxidized from the HO move across the membrane where they move into the material that makes up the biocathode. The new microbe on the biocathode has the ability to transfer the new electrons from the biocathode material and convert them into protons. These protons are then used in the major pathway that drives methane production in electromethanogenesis—CO reduction. CO is brought in on the biocathode side of the system where it is reduced by the protons produced by the microorganisms to yield HO and methane (CH). Methane is produced and can then be released from the biocathode side and stored. | 0 | Theoretical and Fundamental Chemistry |
CCTV drain cameras, also known as sewer cameras or pipe inspection cameras, are a line of waterproof, high definition cameras that have become a widely popular technology in the plumbing profession. These cameras are advanced diagnostic tools that allow plumbers to execute plumbing inspections with heightened accuracy.
These cameras can vary; the main difference being the size of the pipe the camera ca inspect. The total distance they can travel within the pipeline is also a common difference between models. | 1 | Applied and Interdisciplinary Chemistry |
A carbanion is a organic molecule where a carbon atom is not electron deficient but contain an overall negative charge. Carbanions are strong nucleophiles, which can be used to extend an alkene's carbon backbone in the synthesis reaction shown below.
The alkyne carbanion, , is a reaction intermediate in this reaction. | 0 | Theoretical and Fundamental Chemistry |
Some of the earliest known records of mellified corpses come from Greek historian Herodotus (4th century BCE) who recorded that the Assyrians used to embalm their dead with honey. A century later, Alexander the Great's body was reportedly preserved in a honey-filled sarcophagus, and there are also indications that this practice was known to the Egyptians.
Another record of mellification is found in the Bencao Gangmu (section 52, "Man as medicine") under the entry for munaiyi (木乃伊 "mummy"). It quotes the Chuogeng lu (輟耕錄 "Talks while the Plough is Resting", c. 1366) by the Yuan dynasty scholar Tao Zongyi (陶宗儀) and Tao Jiucheng (陶九成).
According to Joseph Needham and Lu Gwei-djen, this content was Arabic, but Li Shizhen confused the story with a Burmese custom of preserving the bodies of abbots and high monks in honey, so that "the Western notion of a drug made from perdurable human flesh was combined with the characteristic Buddhist motif of self-sacrifice for others". In her book Stiff: The Curious Lives of Human Cadavers, writer Mary Roach observes that the text points out that it does not know the veracity of the mellified man story. | 1 | Applied and Interdisciplinary Chemistry |
With no relaxation (that is both T and T → ∞) the above equations simplify to:
or, in vector notation:
This is the equation for Larmor precession of the nuclear magnetization M in an external magnetic field B.
The relaxation terms,
represent an established physical process of transverse and longitudinal relaxation of nuclear magnetization M. | 0 | Theoretical and Fundamental Chemistry |
M. V. George, born on 3 October 1928 in the south Indian state of Kerala, graduated in chemistry from Madras University in 1948 and moved to the Dr. Bhimrao Ambedkar University (then known as Agra University) from where he secured his masters degree in 1951. He did his doctoral studies at St. Johns College, Agra of Agra University under the guidance of P. I. Ittyerah, a former principal of the college, and after securing PhD in 1954, he did his post-doctoral studies at various colleges in the US, UK, Germany and Canada.
He returned to India in 1963 and started his career as a member of faculty at the Indian Institute of Technology, Kanpur. He stayed at the institution for quarter of a century until 1988 during which period he headed the Department of Chemistry from 1966 to 1969, succeeding C. N. R. Rao. Returning to his home state of Kerala in 1988, he joined the Regional Research Laboratory of the Council of Scientific and Industrial Research (present-day National Institute for Interdisciplinary Science and Technology) as an emeritus professor and served the institution until his superannuation from service. In between, he had various stints at the University of Notre Dame as a visiting professor during 1978–2001. | 0 | Theoretical and Fundamental Chemistry |
In 1906, Hahn returned to Germany, where Fischer placed at his disposal a former woodworking shop (Holzwerkstatt) in the basement of the Chemical Institute to use as a laboratory. Hahn equipped it with electroscopes to measure alpha and beta particles and gamma rays. In Montreal these had been made from discarded coffee tins; Hahn made the ones in Berlin from brass, with aluminium strips insulated with amber. These were charged with hard rubber sticks that he rubbed then against the sleeves of his suit. It was not possible to conduct research in the wood shop, but Alfred Stock, the head of the inorganic chemistry department, let Hahn use a space in one of his two private laboratories. Hahn purchased two milligrams of radium from Friedrich Oskar Giesel, the discoverer of emanium (radon), for 100 marks a milligram, and obtained thorium for free from Otto Knöfler, whose Berlin firm was a major producer of thorium products.
In the space of a few months Hahn discovered mesothorium I (radium-228), mesothorium II (actinium-228), and – independently from Boltwood – the mother substance of radium, ionium (later identified as thorium-230). In subsequent years, mesothorium I assumed great importance because, like radium-226 (discovered by Pierre and Marie Curie), it was ideally suited for use in medical radiation treatment, but cost only half as much to manufacture. Along the way, Hahn determined that just as he was unable to separate thorium from radiothorium, so he could not separate mesothorium from radium.
Hahn completed his habilitation in the spring of 1907, and became a Privatdozent. A thesis was not required; the Chemical Institute accepted one of his publications on radioactivity instead. Most of the organic chemists at the Chemical Institute did not regard Hahns work as real chemistry. Fischer objected to Hahns contention in his habilitation colloquium that many radioactive substances existed in such tiny amounts that they could only be detected by their radioactivity, venturing that he had always been able to detect substances with his keen sense of smell, but soon gave in. One department head remarked: "it is incredible what one gets to be a Privatdozent these days!"
Physicists were more accepting of Hahn's work, and he began attending a colloquium at the Physics Institute conducted by Heinrich Rubens. It was at one of these colloquia where, on 28 September 1907, he made the acquaintance of the Austrian physicist Lise Meitner. Almost the same age as himself, she was only the second woman to receive a doctorate from the University of Vienna, and had already published two papers on radioactivity. Rubens suggested her as a possible collaborator. So began the thirty-year collaboration and lifelong close friendship between the two scientists.
In Montreal, Hahn had worked with physicists including at least one woman, Harriet Brooks, but it was difficult for Meitner at first. Women were not yet admitted to universities in Prussia. Meitner was allowed to work in the wood shop, which had its own external entrance, but could not set foot in the rest of the institute, including Hahns laboratory space upstairs. If she wanted to go to the toilet, she had to use one at the restaurant down the street. The following year, women were admitted to universities, and Fischer lifted the restrictions, and had womens toilets installed in the building. The Institute of Physics was more accepting than chemists, and she became friends with the physicists there, including , James Franck, Gustav Hertz, Robert Pohl, Max Planck, and Wilhelm Westphal. | 0 | Theoretical and Fundamental Chemistry |
Various geologic data suggest that Lake Chichoj stretches above of a body of gypsum well exposed on outcrops farther west. There, gypsum dissolution is responsible for repeated mountain flank collapses in the valley of Los Chorros. The lake occupies at least three coalescing dolines likely formed by dissolution of gypsum at depth. The dolines are probably only a few tens of thousands of years old, and the marshlands that surround the lake are likely covering similar, sediment-filled dolines. They are therefore susceptible to resumption of ground subsidence, if gypsum keeps dissolving at depth. The new phase of subsidence could either be slow and continuous, or pulsed, and possibly fast, even instantaneous. It is even possible that the marshes are actively subsiding, since no monitoring of subsidence has ever been undertaken. Subsidence might also be occurring under the combined effect of slow sediment compaction and oxidation/decomposition of the organic matter trapped in the sediments. The accommodation space created by the subsidence would be filled by mineral and organic sediments over the marshlands. | 1 | Applied and Interdisciplinary Chemistry |
* Surgery
* by counseling, such as psychotherapy (see also: list of psychotherapies)
** systemic therapy
** by group psychotherapy
* by cognitive behavioral therapy
** by cognitive therapy
** by behaviour therapy
*** by dialectical behavior therapy
** by cognitive emotional behavioral therapy
* by cognitive rehabilitation therapy
* by family therapy
* by education
** by psychoeducation
** by information therapy
* by speech therapy, physical therapy, occupational therapy, vision therapy, massage therapy, chiropractic or acupuncture
* by lifestyle modifications, such as avoiding unhealthy food or maintaining a predictable sleep schedule
* by coaching | 1 | Applied and Interdisciplinary Chemistry |
A peroxisome () is a membrane-bound organelle, a type of microbody, found in the cytoplasm of virtually all eukaryotic cells. Peroxisomes are oxidative organelles. Frequently, molecular oxygen serves as a co-substrate, from which hydrogen peroxide (HO) is then formed. Peroxisomes owe their name to hydrogen peroxide generating and scavenging activities. They perform key roles in lipid metabolism and the reduction of reactive oxygen species.
Peroxisomes are involved in the catabolism of very long chain fatty acids, branched chain fatty acids, bile acid intermediates (in the liver), D-amino acids, and polyamines. Peroxisomes also play a role in the biosynthesis of plasmalogens: ether phospholipids critical for the normal function of mammalian brains and lungs. Peroxisomes contain approximately 10% of the total activity of two enzymes (Glucose-6-phosphate dehydrogenase and 6-Phosphogluconate dehydrogenase) in the pentose phosphate pathway, which is important for energy metabolism. It is vigorously debated whether peroxisomes are involved in isoprenoid and cholesterol synthesis in animals. Other peroxisomal functions include the glyoxylate cycle in germinating seeds ("glyoxysomes"), photorespiration in leaves, glycolysis in trypanosomes ("glycosomes"), and methanol and amine oxidation and assimilation in some yeasts. | 1 | Applied and Interdisciplinary Chemistry |
Records of bioluminescence due to bacteria have existed for thousands of years. They appear in the folklore of many regions, including Scandinavia and the Indian subcontinent. Both Aristotle and Charles Darwin have described the phenomenon of the oceans glowing. Since its discovery less than 30 years ago, the enzyme luciferase and its regulatory gene, lux, have led to major advances in molecular biology, through use as a reporter gene. Luciferase was first purified by McElroy and Green in 1955. It was later discovered that there were two subunits to luciferase, called subunits α and β. The genes encoding these enzymes, luxA and luxB, respectively, were first isolated in the lux operon of Aliivibrio fisheri. | 1 | Applied and Interdisciplinary Chemistry |
Aqueous solutions of transition metals cations react with sulfide sources (HS, NaHS, NaS) to precipitate solid sulfides. Such inorganic sulfides typically have very low solubility in water, and many are related to minerals with the same composition (see below). One famous example is the bright yellow species CdS or "cadmium yellow". The black tarnish formed on sterling silver is AgS. Such species are sometimes referred to as salts. In fact, the bonding in transition metal sulfides is highly covalent, which gives rise to their semiconductor properties, which in turn is related to the deep colors. Several have practical applications as pigments, in solar cells, and as catalysts. The fungus Aspergillus niger plays a role in the solubilization of heavy metal sulfides. | 0 | Theoretical and Fundamental Chemistry |
In 2015, an 18-year-old female karateka (martial arts practitioner) from Egypt gave a urine sample in order for her drugs test to be administered. It was found that the urine contained too much ractopamine and the athlete was sanctioned with ineligibility for four years. The sole arbitrator from the Court of Arbitration for Sport said that ractopamine "is not specifically mentioned by name in the World Anti-Doping Code ("WADC"), but is an Other Anabolic Agent prohibited under S1.2 of the 2015 Prohibited List under the WADC... Athlete did not fulfil her burden of proof to establish the origin of the prohibited substance, [and thus] she has committed an anti-doping rule violation".
In October 2017 at a World Anti-Doping Agency conference, it was suggested in relation with ractopamine
One conclusion reached in October 2017 was that there was a "clear risk for athletes to be tested positive" when consuming meat with residues at the MRL concentration. | 0 | Theoretical and Fundamental Chemistry |
Since 2000, Dr Brills interest in Silk Road studies and ancient glass compositions has continued, but his publication rate has slowed somewhat. His years of prolific publication, however, and his willingness to analyse glass from almost every situation have provided the archaeometry of glass with a bounty of reference material, as reflected by the Chemical Analyses of Early Glasses. Despite his official retirement from the Corning Museum of Glass on May 31, 2008, he returned to the laboratory the next day and continues to work, showing no intention of enjoying a retirement proper any time soon (Brill, pers. comm.', 2009). | 0 | Theoretical and Fundamental Chemistry |
* Camille and Henry Dreyfus New Faculty Award (2004)
* National Science Foundation (NSF) Career Award (2008)
* Alfred P. Sloan Fellowship Award (2010)
* Heaton Family Faculty Award (2011) | 0 | Theoretical and Fundamental Chemistry |
*Carnegie-Mellon University in Pittsburgh
*University of Liège in Belgium
*Nicolaus Copernicus University Medical School in Kraków, Poland | 0 | Theoretical and Fundamental Chemistry |
In organometallic chemistry, metal sulfur dioxide complexes are complexes that contain sulfur dioxide, , bonded to a transition metal. Such compounds are common but are mainly of theoretical interest. Historically, the study of these compounds has provided insights into the mechanisms of migratory insertion reactions. | 0 | Theoretical and Fundamental Chemistry |
Usually, but not universally, the numbers indicate:
* the first digit corresponds to the furnace number
* the second digit indicates the year in which the material was melted
* the last three (and sometimes four) indicate the melt number. | 1 | Applied and Interdisciplinary Chemistry |
Strictly speaking, this reaction results in the formation of a rhodium carbonyl complex rather than free carbon monoxide.
The catalytic cycle is assumed to involve oxidative addition of the aldehyde (or acid chloride) to gives a 16e acyl Rh(III)-hydride intermediate, which undergoes migratory extrusion of CO proceed to form an 18-electron d6 Rh(III) carbonyl complex. Reductive elimination produces the decarbonylated product. In the catalytic variant of the Tsuji–Wilkinson decarbonylation, RhCl(CO)(PPh) evolves CO above 200 °C, thereby regenerating RhCl(PPh). Otherwise, the reaction mechanism halts by formation of this thermodynamically stable carbonyl complex. | 0 | Theoretical and Fundamental Chemistry |
As with many other small mammal species, M. pennsylvanicus plays important ecological roles. The eastern meadow vole is an important food source for many predators, and disperses mycorrhizal fungi. It is a major consumer of grass and disperses grass nutrients in its feces. After disruptive site disturbances such as forest or meadow fires, the meadow vole's activities contribute to habitat restoration. It prefers open, nonforest habitats and colonizes such open areas created by fire or other clearing disturbances. Very few eastern meadow voles are found in forest or woodland areas. In newly opened areas, it is quite abundant. In these new open areas, the vole quickly becomes a food source for predators. | 1 | Applied and Interdisciplinary Chemistry |
A critical role for the ER in calcium signaling was acknowledged before such a role for the mitochondria was widely accepted, in part because the low affinity of Ca channels localized to the outer mitochondrial membrane seemed to contradict this organelle's purported responsiveness to changes in intracellular Ca flux. But the presence of the MAM resolves this apparent contradiction: the close physical association between the two organelles results in Ca microdomains at contact points that facilitate efficient Ca transmission from the ER to the mitochondria. Transmission occurs in response to so-called "Ca puffs" generated by spontaneous clustering and activation of IP3R, a canonical ER membrane Ca channel.
The fate of these puffs—in particular, whether they remain restricted to isolated locales or integrated into Ca waves for propagation throughout the cell—is determined in large part by MAM dynamics. Although reuptake of Ca by the ER (concomitant with its release) modulates the intensity of the puffs, thus insulating mitochondria to a certain degree from high Ca exposure, the MAM often serves as a firewall that essentially buffers Ca puffs by acting as a sink into which free ions released into the cytosol can be funneled. This Ca tunneling occurs through the low-affinity Ca receptor VDAC1, which recently has been shown to be physically tethered to the IP3R clusters on the ER membrane and enriched at the MAM. The ability of mitochondria to serve as a Ca sink is a result of the electrochemical gradient generated during oxidative phosphorylation, which makes tunneling of the cation an exergonic process. Normal, mild calcium influx from cytosol into the mitochondrial matrix causes transient depolarization that is corrected by pumping out protons.
But transmission of Ca is not unidirectional; rather, it is a two-way street. The properties of the Ca pump SERCA and the channel IP3R present on the ER membrane facilitate feedback regulation coordinated by MAM function. In particular, the clearance of Ca by the MAM allows for spatio-temporal patterning of Ca signaling because Ca alters IP3R activity in a biphasic manner. SERCA is likewise affected by mitochondrial feedback: uptake of Ca by the MAM stimulates ATP production, thus providing energy that enables SERCA to reload the ER with Ca for continued Ca efflux at the MAM. Thus, the MAM is not a passive buffer for Ca puffs; rather it helps modulate further Ca signaling through feedback loops that affect ER dynamics.
Regulating ER release of Ca at the MAM is especially critical because only a certain window of Ca uptake sustains the mitochondria, and consequently the cell, at homeostasis. Sufficient intraorganelle Ca signaling is required to stimulate metabolism by activating dehydrogenase enzymes critical to flux through the citric acid cycle. However, once Ca signaling in the mitochondria passes a certain threshold, it stimulates the intrinsic pathway of apoptosis in part by collapsing the mitochondrial membrane potential required for metabolism. Studies examining the role of pro- and anti-apoptotic factors support this model; for example, the anti-apoptotic factor Bcl-2 has been shown to interact with IP3Rs to reduce Ca filling of the ER, leading to reduced efflux at the MAM and preventing collapse of the mitochondrial membrane potential post-apoptotic stimuli. Given the need for such fine regulation of Ca signaling, it is perhaps unsurprising that dysregulated mitochondrial Ca has been implicated in several neurodegenerative diseases, while the catalogue of tumor suppressors includes a few that are enriched at the MAM. | 1 | Applied and Interdisciplinary Chemistry |
There are three major epidermal cell types which all ultimately derive from the outermost (L1) tissue layer of the shoot apical meristem, called protodermal cells: trichomes, pavement cells and guard cells, all of which are arranged in a non-random fashion.
An asymmetrical cell division occurs in protodermal cells resulting in one large cell that is fated to become a pavement cell and a smaller cell called a meristemoid that will eventually differentiate into the guard cells that surround a stoma. This meristemoid then divides asymmetrically one to three times before differentiating into a guard mother cell. The guard mother cell then makes one symmetrical division, which forms a pair of guard cells. Cell division is inhibited in some cells so there is always at least one cell between stomata.
Stomatal patterning is controlled by the interaction of many signal transduction components such as EPF (Epidermal Patterning Factor), ERL (ERecta Like) and YODA (a putative MAP kinase kinase kinase). Mutations in any one of the genes which encode these factors may alter the development of stomata in the epidermis. For example, a mutation in one gene causes more stomata that are clustered together, hence is called Too Many Mouths (TMM). Whereas, disruption of the SPCH (SPeecCHless) gene prevents stomatal development all together. Inhibition of stomatal production can occur by the activation of EPF1, which activates TMM/ERL, which together activate YODA. YODA inhibits SPCH, causing SPCH activity to decrease, preventing asymmetrical cell division that initiates stomata formation. Stomatal development is also coordinated by the cellular peptide signal called stomagen, which signals the activation of the SPCH, resulting in increased number of stomata.
Environmental and hormonal factors can affect stomatal development. Light increases stomatal development in plants; while, plants grown in the dark have a lower amount of stomata. Auxin represses stomatal development by affecting their development at the receptor level like the ERL and TMM receptors. However, a low concentration of auxin allows for equal division of a guard mother cell and increases the chance of producing guard cells.
Most angiosperm trees have stomata only on their lower leaf surface. Poplars and willows have them on both surfaces. When leaves develop stomata on both leaf surfaces, the stomata on the lower surface tend to be larger and more numerous, but there can be a great degree of variation in size and frequency about species and genotypes. White ash and white birch leaves had fewer stomata but larger in size. On the other hand sugar maple and silver maple had small stomata that were more numerous. | 0 | Theoretical and Fundamental Chemistry |
Gregor was made an honorary member of the Geological Society of London on its inception in 1807, and was a founding member of the Royal Geological Society of Cornwall in 1814. His friends and correspondents included John Hawkins, Philip Rashleigh and John Ayrton Paris. Never letting his scientific work interfere with his pastoral duties, he was also a distinguished landscape painter, etcher and musician. He died of tuberculosis on 11 June 1817 and was buried at nearby Cornelly church. | 1 | Applied and Interdisciplinary Chemistry |
* Manaus, Brazil is on the Rio Negro near its confluence with the Amazon (see Meeting of Waters). It is the chief port and a hub for the region's extensive river system.
* The Iguazú flows into the Paraná at the "Triple Frontier" (, ), the tripoint for Paraguay, Argentina, and Brazil.
* In Ciudad Guayana, Venezuela there is a confluence between Orinoco River and Caroní River. | 1 | Applied and Interdisciplinary Chemistry |
Given a flow and head for a specific hydro site, and the RPM requirement of the generator, calculate the specific speed. The result is the main criteria for turbine selection or the starting point for analytical design of a new turbine. Once the desired specific speed is known, basic dimensions of the turbine parts can be easily calculated.
Turbine calculations:
: = Runner diameter (m) | 1 | Applied and Interdisciplinary Chemistry |
In materials where the maximum applied-stress-intensity factor exceeds the stress-corrosion cracking-threshold value, stress corrosion adds to crack-growth velocity. This is shown in the schematic on the right. In a corrosive environment, the crack grows due to cyclic loading at a lower stress-intensity range; above the threshold stress intensity for stress corrosion cracking, additional crack growth (the red line) occurs due to SCC. The lower stress-intensity regions are not affected, and the threshold stress-intensity range for fatigue-crack propagation is unchanged in the corrosive environment. In the most-general case, corrosion-fatigue crack growth may exhibit both of the above effects; crack-growth behavior is represented in the schematic on the left. | 1 | Applied and Interdisciplinary Chemistry |
Monocrystalline silicon (mono-Si) solar cells feature a single-crystal composition that enables electrons to move more freely than in a multi-crystal configuration. Consequently, monocrystalline solar panels deliver a higher efficiency than their multicrystalline counterparts. The corners of the cells look clipped, like an octagon, because the wafer material is cut from cylindrical ingots, that are typically grown by the Czochralski process. Solar panels using mono-Si cells display a distinctive pattern of small white diamonds. | 0 | Theoretical and Fundamental Chemistry |
Hérisson and Chauvin first proposed the widely accepted mechanism of transition metal alkene metathesis. The direct [2+2] cycloaddition of two alkenes is formally symmetry forbidden and thus has a high activation energy. The Chauvin mechanism involves the [2+2] cycloaddition of an alkene double bond to a transition metal alkylidene to form a metallacyclobutane intermediate. The metallacyclobutane produced can then cycloeliminate to give either the original species or a new alkene and alkylidene. Interaction with the d-orbitals on the metal catalyst lowers the activation energy enough that the reaction can proceed rapidly at modest temperatures.
Olefin metathesis involves little change in enthalpy for unstrained alkenes. Product distributions are determined instead by le Chatelier's Principle, i.e. entropy.
Cross metathesis and ring-closing metathesis are driven by the entropically favored evolution of ethylene or propylene, which can be removed from the system because they are gases. Because of this CM and RCM reactions often use alpha-olefins. The reverse reaction of CM of two alpha-olefins, ethenolysis, can be favored but requires high pressures of ethylene to increase ethylene concentration in solution. The reverse reaction of RCM, ring-opening metathesis, can likewise be favored by a large excess of an alpha-olefin, often styrene. Ring-opening metathesis usually involves a strained alkene (often a norbornene) and the release of ring strain drives the reaction. Ring-closing metathesis, conversely, usually involves the formation of a five- or six-membered ring, which is enthalpically favorable; although these reactions tend to also evolve ethylene, as previously discussed. RCM has been used to close larger macrocycles, in which case the reaction may be kinetically controlled by running the reaction at high dilutions. The same substrates that undergo RCM can undergo acyclic diene metathesis, with ADMET favored at high concentrations. The Thorpe–Ingold effect may also be exploited to improve both reaction rates and product selectivity.
Cross-metathesis is synthetically equivalent to (and has replaced) a procedure of ozonolysis of an alkene to two ketone fragments followed by the reaction of one of them with a Wittig reagent. | 0 | Theoretical and Fundamental Chemistry |
A date rape drug is any drug that is an incapacitating agent which—when administered to another person—incapacitates the person and renders them vulnerable to a drug-facilitated sexual assault (DFSA), including rape. One of the most common types of DFSA are those in which a victim consumes a recreational drug such as alcohol that was administered surreptitiously. The other most common form of DFSA involves the non-surreptitiously administered consumption of alcohol. Here, the victims in these cases are drinking voluntarily which then makes them unable to make informed decisions or give consent. | 1 | Applied and Interdisciplinary Chemistry |
;Bridge books by Rosenkranz
* The Romex System of Bidding: a dynamic approach to bridge (New York: World Publishing Co., 1970)
* Win with Romex: the key to accurate bidding (Crown Publishers, 1975)
* Bid Your Way to the Top (New York state: Barclay Bridge Supplies, 1978)
* Bridge, the Bidders Game' (Louisville, KY: Devyn Press, 1985)
* Slam Bidding (Devyn, 1985) – Championship bridge series, no. 33
* Everything You Always Wanted to Know About Trump Leads and Were Not Afraid to Ask (Devyn, 1986)
* Tips for Tops (Devyn, 1988)
* More Tips for Tops (Devyn, 1991)
* Our Man Godfrey: tales from the bridge table (Devyn, 1994), ed. Phillip Alder – love story and bridge instruction
;Bridge books with co-authors
* Modern Ideas in Bidding (Devyn, 1982), with Alan Truscott
* Bid to Win, Play for Pleasure (Devyn, 1990), with Alder
* Bidding on Target (Devyn, 1992), with Truscott and Alder
* Godfreys Bridge Challenge' (Devyn, 1996), with Alder
* Godfreys Stairway To The Stars: a step-by-step guide to modern bidding' (Devyn, 1998), with Alder
* Godfreys Angels' (Devyn, 2001), with Alder
The four Godfrey books combine fictional narrative and instructional bridge. The second, and first with co-author credit to Phillip Alder, Godfreys Bridge Challenge "brings the Romex system to life through lively anecdotes instruction and quizzes". The last, Godfreys Angels incorporates 1998–2001 improvements in the system.
;Memoir
* George and Edith Rosenkranz: a memoir of their lives and times (Philadelphia: Science History Consultants, 2011), with editor Arnold Thackray, | 0 | Theoretical and Fundamental Chemistry |
A parasympatholytic agent is a substance or activity that reduces the activity of the parasympathetic nervous system.
The term parasympatholytic typically refers to the effect of a drug, although some poisons act to block the parasympathetic nervous system as well. Most drugs with parasympatholytic properties are anticholinergics.
Parasympatholytic agents and sympathomimetic agents have similar effects to each other, although some differences between the two groups can be observed. For example, both cause mydriasis, but parasympatholytics reduce accommodation (cycloplegia), whereas sympathomimetics do not.
__NOTOC__ | 1 | Applied and Interdisciplinary Chemistry |
Polyprotein processing is adopted by 45% of plant viruses, such as the Potyviridae and Tymoviridae. The ribosome translates a single protein from the viral genome. Within the polyprotein is an enzyme (or enzymes) with proteinase function that is able to cleave the polyprotein into the various single proteins or just cleave away the protease, which can then cleave other polypeptides producing the mature proteins. | 1 | Applied and Interdisciplinary Chemistry |
If the incoming photon is polarized, the scattered photon is no longer isotropic with respect to the azimuthal angle. For a linearly polarized photon scattered with a free electron at rest, the differential cross section is instead given by:
where is the azimuthal scattering angle. Note that the unpolarized differential cross section can be obtained by averaging over . | 0 | Theoretical and Fundamental Chemistry |
In coastal engineering, a tetrapod is a four-legged concrete structure used as armour unit on breakwaters. The tetrapod's shape is designed to dissipate the force of incoming waves by allowing water to flow around rather than against it, and to reduce displacement by allowing a random distribution of tetrapods to mutually interlock. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, the valence (US spelling) or valency (British spelling) of an atom is a measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Valence is generally understood to be the number of chemical bonds that each atom of a given chemical element typically forms. Double bonds are considered to be two bonds, triple bonds to be three, quadruple bonds to be four, quintuple bonds to be five and sextuple bonds to be six. In most compounds, the valence of hydrogen is 1, of oxygen is 2, of nitrogen is 3, and of carbon is 4. Valence is not to be confused with the related concepts of the coordination number, the oxidation state, or the number of valence electrons for a given atom. | 0 | Theoretical and Fundamental Chemistry |
TRIzol is a widely used chemical solution used in the extraction of DNA, RNA, and proteins from cells. The solution was initially used and published by Piotr Chomczyński and Nicoletta Sacchi in 1987.
TRIzol is the brand name of guanidinium thiocyanate from the Ambion part of Life Technologies, and Tri-Reagent is the brand name from MRC, which was founded by Chomczynski. | 1 | Applied and Interdisciplinary Chemistry |
Daily intakes of fluoride can vary significantly according to the various sources of exposure. Values ranging from 0.46 to 3.6–5.4 mg/day have been reported in several studies (IPCS, 1984). In areas where water is fluoridated this can be expected to be a significant source of fluoride, however fluoride is also naturally present in virtually all foods and beverages at a wide range of concentrations. The maximum safe daily consumption of fluoride is 10 mg/day for an adult (U.S.) or 7 mg/day (European Union).
The upper limit of fluoride intake from all sources (fluoridated water, food, beverages, fluoride dental products and dietary fluoride supplements) is set at 0.10 mg/kg/day for infants, toddlers, and children through to 8 years old. For older children and adults, who are no longer at risk for dental fluorosis, the upper limit of fluoride is set at 10 mg/day regardless of weight. | 1 | Applied and Interdisciplinary Chemistry |
Several efficient techniques are available to detect the presence of distonic ions; the most appropriate method will depend on the ions internal energy and lifespan. Collisions between ions and uncharged molecules allow one to detect the location of the radical and charge site in order to confirm that the ion is not just a regular radical ion. When a molecule is ionized and can structurally be classified as a distonic ion, the molecules kinetics and thermodynamic properties have been greatly altered. However, additional chemical properties are based on the reactions of the central excited ions. Mass spectrometry techniques are used to study their chemistry. | 0 | Theoretical and Fundamental Chemistry |
Tapioca starch can be burnt off easily through the sintering process and is insoluble in titanium. Titanium foams consisting of a bimodal pore distribution (macropores ranging from 100 to 300 μm) and 64–79% porosity, exhibited yield strengths of 23–41 MPa and Young's moduli of 1.6–3.7 GPa. | 0 | Theoretical and Fundamental Chemistry |
The original work on PCP ligands arose from studies of the Pt(II) complexes derived from long-chain ditertiary phosphines, species of the type RP(CH)PR where n >4 and R = tert-butyl. Platinum metalates one methylene group with release of HCl, giving species such as PtCl(RP(CH)CH(CH)PR).
Pincer complexes catalyze the dehydrogenation of alkanes. Early reports described the dehydrogenation of cyclooctane by an Ir pincer complex with a turnover frequency of 12 min at 200 °C. The complexes are thermally stable at such temperatures for days. | 0 | Theoretical and Fundamental Chemistry |
Despite the high number of MAPK genes, MAPK pathways of higher plants were studied less than animal or fungal ones. Although their signaling appears very complex, the MPK3, MPK4 and MPK6 kinases of Arabidopsis thaliana are key mediators of responses to osmotic shock, oxidative stress, response to cold and involved in anti-pathogen responses. Asai et al. 2002s model of MAPK mediated immunity passes the effector recognition signal from FLS2 ⇨ MEKK1 ⇨ MKK4 or MKK5 ⇨ MPK3 and MPK6 ⇨ WRKY22 or WRKY29. However the work of Mészáros et al. 2006 and Suarez-Rodriguez et al.' 2007 give other orders for this pathway and it is possible that these are parallel pathways operating simultaneously. They are also involved in morphogenesis, since MPK4 mutants display severe dwarfism. | 1 | Applied and Interdisciplinary Chemistry |
An electrostatic lens is a device that assists in the transport of charged particles. For instance, it can guide electrons emitted from a sample to an electron analyzer, analogous to the way an optical lens assists in the transport of light in an optical instrument. Systems of electrostatic lenses can be designed in the same way as optical lenses, so electrostatic lenses easily magnify or converge the electron trajectories. An electrostatic lens can also be used to focus an ion beam, for example to make a microbeam for irradiating individual cells. | 0 | Theoretical and Fundamental Chemistry |
The epithelial–mesenchymal transition (EMT) is a process by which epithelial cells lose their cell polarity and cell–cell adhesion, and gain migratory and invasive properties to become mesenchymal stem cells; these are multipotent stromal cells that can differentiate into a variety of cell types. EMT is essential for numerous developmental processes including mesoderm formation and neural tube formation. EMT has also been shown to occur in wound healing, in organ fibrosis and in the initiation of metastasis in cancer progression. | 1 | Applied and Interdisciplinary Chemistry |
In cellular biology, P-bodies, or processing bodies, are distinct foci formed by phase separation within the cytoplasm of a eukaryotic cell consisting of many enzymes involved in mRNA turnover. P-bodies are highly conserved structures and have been observed in somatic cells originating from vertebrates and invertebrates, plants and yeast. To date, P-bodies have been demonstrated to play fundamental roles in general mRNA decay, nonsense-mediated mRNA decay, adenylate-uridylate-rich element mediated mRNA decay, and microRNA (miRNA) induced mRNA silencing. Not all mRNAs which enter P-bodies are degraded, as it has been demonstrated that some mRNAs can exit P-bodies and re-initiate translation. Purification and sequencing of the mRNA from purified processing bodies showed that these mRNAs are largely translationally repressed upstream of translation initiation and are protected from 5' mRNA decay.
P-bodies were originally proposed to be the sites of mRNA degradation in the cell and involved in decapping and digestion of mRNAs earmarked for destruction. Later work called this into question suggesting P bodies store mRNA until needed for translation.
In neurons, P-bodies are moved by motor proteins in response to stimulation. This is likely tied to local translation in dendrites. | 1 | Applied and Interdisciplinary Chemistry |
Common adverse effects are similar to other antihypertensive drugs and include headache, vertigo, and drowsiness. A dry cough is common as with all ACE inhibitors. Other possible adverse effects are described at ACE inhibitor#Adverse effects. | 0 | Theoretical and Fundamental Chemistry |
lactalbumin - lactic acid - lactic acid autotroph - lactic fermentation - lagging strand - laminin - LDL receptor - Le Chatelier's principle - lectin - leucine - leucine-2-alanine enkephalin - leukotriene B4 receptor - LH - LH receptor - LHRH receptor - life - life form - ligand - light reactions - Lineweaver-Burk diagram - lipase - lipid - lipid anchored protein - lipid bilayer - lipoprotein - liquid - list of compounds - list of gene families - locus - luminescent protein - lymphocyte homing receptor - lysine - lysis - lysis buffer - lysozyme - lytic cycle | 1 | Applied and Interdisciplinary Chemistry |
In physics, Mott scattering also referred to as spin-coupling inelastic Coulomb scattering, is the separation of the two spin states of an electron beam by scattering the beam off the Coulomb field of heavy atoms. It is named after Nevill Francis Mott, who first developed the theory. It is mostly used to measure the spin polarization of an electron beam.
In lay terms, Mott scattering is similar to Rutherford scattering but electrons are used instead of alpha particles as they do not interact via the strong interaction (only through weak interaction and electromagnetism), which enable electrons to penetrate the atomic nucleus, giving valuable insight into the nuclear structure. | 0 | Theoretical and Fundamental Chemistry |
Since the mechanism of action of thalidomide and its analogs is not fully clear and the bioreceptor for these substances has not been identified, the insight into the relationship between the structure and activity of thalidomide and its analogs are mostly derived from molecular modelling and continued research investigation.
The information on SAR of thalidomide and its analogs is still in process so any trends detailed here are observed during individual studies.
Research has mainly focused on improving the TNF-α and PDE4 inhibition of thalidomide, as well as the anti-angiogenesis activity. | 1 | Applied and Interdisciplinary Chemistry |
UCP1 is expressed in brown adipose tissue, which is functionally found only in eutherians. The UCP1, or thermogenin, gene likely arose in an ancestor of modern vertebrates, but did not initially allow for our vertebrate ancestor to use non-shivering thermogenesis for warmth. It wasn't until heat generation was adaptively selected for in placental mammal descendants of this common ancestor that UCP1 evolved its current function in brown adipose tissue to provide additional warmth. While UCP1 plays a key thermogenic role in wide range placental mammals, particularly those with small body size and those that hibernate, the UCP1 gene has lost functionality in several large-bodied lineages (e.g. horses, elephants, sea cows, whales and hyraxes) and lineages with low metabolic rates (e.g. pangolins, armadillos, sloths and anteaters). Recent discoveries of non-heat-generating orthologues of UCP1 in fish and marsupials, other descendants of the ancestor of modern vertebrates, show that this gene was passed on to all modern vertebrates, but aside from placental mammals, none have heat producing capability. This further suggests that UCP1 had a different original purpose and in fact phylogenetic and sequence analyses indicate that UCP1 is likely a mutated form of a dicarboxylate carrier protein that adapted for thermogenesis in placental mammals. | 1 | Applied and Interdisciplinary Chemistry |
The dithionite is the oxyanion with the formula [SO]. It is commonly encountered as the salt sodium dithionite. For historical reasons, it is sometimes called hydrosulfite, but it contains no hydrogen and is not a sulfite. The dianion has a steric number of 4 and trigonal pyramidal geometry. | 1 | Applied and Interdisciplinary Chemistry |
Chain reaction in chemistry and physics is a process that produces products capable of initiating subsequent processes of a similar nature. It is a self-sustaining sequence in which the resulting products continue to propagate further reactions. Examples of chain reactions in living organisms are lipid peroxidation in cell membranes and propagation of excitation of neurons in epilepsy. | 1 | Applied and Interdisciplinary Chemistry |
Induced metabolic bioluminescence imaging (imBI) is used to obtain a metabolic snapshot of biological tissues. Metabolites that may be quantified through imBI include glucose, lactate, pyruvate, ATP, glucose-6-phosphate, or D2-hydroxygluturate. imBI can be used to determine the lactate concentration of tumors or to measure the metabolism of the brain. | 1 | Applied and Interdisciplinary Chemistry |
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