text stringlengths 105 4.57k | label int64 0 1 | label_text stringclasses 2 values |
|---|---|---|
* gas silvestre
**Ancient origin for fixed air by Jan Baptist van Helmont
*Spiritus sylvestris
*aerial acid
*acid of air
*luft-saeure
*carbonic anhydride
*Gas acide carbonique
*Gas carbonicum
*chalky acid
*acid of chalk
*kriedesaeure
*kohlensaeures gas
*choke-damp
*cretaceous acid
*Acide mephitique
*Mephitic air
*deutoxide of carbon | 1 | Applied and Interdisciplinary Chemistry |
Deoxycytidine triphosphate (dCTP) is a nucleoside triphosphate that contains the pyrimidine base cytosine. The triphosphate group contains high-energy phosphoanhydride bonds, which liberate energy when hydrolized.
DNA polymerase enzymes use this energy to incorporate deoxycytidine into a newly synthesized strand of DNA. A chemical equation can be written that represents the process:
: (DNA) + dCTP ↔ (DNA)-C + PP
That is, dCTP has the PP (pyrophosphate) cleaved off and the dCMP is incorporated into the DNA strand at the 3' end.
Subsequent hydrolysis of the PP drives the equilibrium of the reaction toward the right side, i.e. incorporation of the nucleotide in the growing DNA chain.
Like other nucleoside triphosphates, manufacturers recommend that dCTP be stored in aqueous solution at −20 °C. | 1 | Applied and Interdisciplinary Chemistry |
In order to reduce humidity levels and spoiling due to bacterial growth, refrigeration is used for meat, produce, and dairy processing in farming today. Refrigeration systems are used the heaviest in the warmer months for farming produce, which must be cooled as soon as possible in order to meet quality standards and increase the shelf life. Meanwhile, dairy farms refrigerate milk year round to avoid spoiling. | 0 | Theoretical and Fundamental Chemistry |
Phenols are more acidic than typical alcohols. The acidity of the hydroxyl group in phenols is commonly intermediate between that of aliphatic alcohols and carboxylic acids (their pK is usually between 10 and 12). Deprotonation of a phenol forms a corresponding negative phenolate ion or phenoxide ion, and the corresponding salts are called phenolates or phenoxides (aryloxides according to the IUPAC Gold Book). | 0 | Theoretical and Fundamental Chemistry |
A common method of quantitative nitrite detection is the Griess test, which relies on the reaction of nitrite with the two components of a Griess reagent to form a red azo dye. This allows the concentration of nitrite to be determined by UV-vis spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
Transition metal alkyne complexes are often formed by the displacement of labile ligands by the alkyne. For example, a variety of cobalt-alkyne complexes arise by the reaction of alkynes with dicobalt octacarbonyl.
Many alkyne complexes are produced by reduction of metal halides:
: CpTiCl + Mg + MeSiC≡CSiMe → CpTi[(CSiMe)] + MgCl | 0 | Theoretical and Fundamental Chemistry |
The Association of Environmental Professionals (AEP) is a California-based non-profit organization of interdisciplinary professionals including environmental science, resource management, environmental planning and other professions contributing to this field. AEP is the first organization of its kind in the USA, and its influence and model have spawned numerous other regional organizations throughout the United States, as well as the separate National Association of Environmental Professionals (NAEP). From inception in the mid-1970s the organization has been closely linked with the upkeep of the California Environmental Quality Act (CEQA), California being one of the first states to adopt a comprehensive law to govern the environmental review of public policy and project review. | 1 | Applied and Interdisciplinary Chemistry |
An additional environmental benefit of a green roof is the ability to sequester carbon. Carbon is the main component of plant matter and is naturally absorbed by plant tissue. The carbon is stored in the plant tissue and the soil substrate through plant litter and root exudates. A study on green roofs in Michigan and Maryland found the above ground biomass and below ground substrate stored on average between 168 g C m and 107 g C m . Variations occurred among the different species of plant used. Substrate carbon content averaged 913 g C m and after the subtraction of the original carbon content the total sequestration was 378 g C m. The sequestration can be improved by changing plant species, increasing substrate depth, substrate composition, and management practices. In a study done in Michigan above ground sequestration ranged from 64 g C m to 239 g C m for S. acre and S album. Also, by increasing the substrate depth would allow for more area of carbon storage and diversify the types of plants with greater potential of carbon storage. The direct carbon sequestration techniques and methods can be measured and accounted for. Green roofs also indirectly reduce CO given off by power plants through their ability to insulate buildings. Buildings in the US account for 38% of the total carbon dioxide emissions. A model supported by the U.S. Department of Energy found a 2 percent reduction in electricity consumption and 9-11% reduction in natural gas when implementing green roofs. | 1 | Applied and Interdisciplinary Chemistry |
Finally, the bioactive molecule of interest is loaded into the carbohydrate layer. This process typically occurs through either lyophilization or passive adsorption, and the fully functionalized aquasome is then characterized. | 0 | Theoretical and Fundamental Chemistry |
The biological pump, in its simplest form, is the ocean's biologically driven sequestration of carbon from the atmosphere to the ocean interior and seafloor sediments. It is the part of the oceanic carbon cycle responsible for the cycling of organic matter formed mainly by phytoplankton during photosynthesis (soft-tissue pump), as well as the cycling of calcium carbonate (CaCO) formed into shells by certain organisms such as plankton and mollusks (carbonate pump).
The biological pump can be divided into three distinct phases, the first of which is the production of fixed carbon by planktonic phototrophs in the euphotic (sunlit) surface region of the ocean. In these surface waters, phytoplankton use carbon dioxide (CO), nitrogen (N), phosphorus (P), and other trace elements (barium, iron, zinc, etc.) during photosynthesis to make carbohydrates, lipids, and proteins. Some plankton, (e.g. coccolithophores and foraminifera) combine calcium (Ca) and dissolved carbonates (carbonic acid and bicarbonate) to form a calcium carbonate (CaCO) protective coating.
Once this carbon is fixed into soft or hard tissue, the organisms either stay in the euphotic zone to be recycled as part of the regenerative nutrient cycle or once they die, continue to the second phase of the biological pump and begin to sink to the ocean floor. The sinking particles will often form aggregates as they sink, greatly increasing the sinking rate. It is this aggregation that gives particles a better chance of escaping predation and decomposition in the water column and eventually make it to the sea floor.
The fixed carbon that is either decomposed by bacteria on the way down or once on the sea floor then enters the final phase of the pump and is remineralized to be used again in primary production. The particles that escape these processes entirely are sequestered in the sediment and may remain there for millions of years. It is this sequestered carbon that is responsible for ultimately lowering atmospheric CO.
* Brum JR, Morris JJ, Décima M and Stukel MR (2014) "Mortality in the oceans: Causes and consequences". Eco-DAS IX Symposium Proceedings, Chapter 2, pages 16–48. Association for the Sciences of Limnology and Oceanography. .
* Mateus, M.D. (2017) "Bridging the gap between knowing and modeling viruses in marine systems—An upcoming frontier". Frontiers in Marine Science, 3: 284.
* Beckett, S.J. and Weitz, J.S. (2017) "Disentangling niche competition from grazing mortality in phytoplankton dilution experiments". PLOS ONE, 12(5): e0177517. . | 0 | Theoretical and Fundamental Chemistry |
Ion beams produced by ion and plasma thrusters on board a spacecraft can be used to transmit a force to a nearby object (e.g. another spacecraft, an asteroid, etc.) that is irradiated by the beam. This innovative propulsion technique named Ion Beam Shepherd has been shown to be effective in the area of active space debris removal as well as asteroid deflection. | 0 | Theoretical and Fundamental Chemistry |
A quench press is a machine that uses concentrated forces to hold an object as it is quenched. These types of quench facilities are used to quench large gears and other circular parts so that they remain circular. They are also used to quench saw blades and other flat or plate-shaped objects so that they remain flat.
Quench presses are able to quench the part while it is being held because of the unique structure of the clamps holding the part. Clamps are slotted so that oil or water can flow through each slot and cool the part and the ribs of the clamps can hold the part in place. | 1 | Applied and Interdisciplinary Chemistry |
There are three common naming conventions for specifying one of the two enantiomers (the absolute configuration) of a given chiral molecule: the R/S system is based on the geometry of the molecule; the (+)- and (−)- system (also written using the obsolete equivalents d- and l-) is based on its optical rotation properties; and the / system is based on the molecule's relationship to enantiomers of glyceraldehyde.
The R/S system is based on the molecule's geometry with respect to a chiral center. The R/S system is assigned to a molecule based on the priority rules assigned by Cahn–Ingold–Prelog priority rules, in which the group or atom with the largest atomic number is assigned the highest priority and the group or atom with the smallest atomic number is assigned the lowest priority.
The (+)- and (−)- is used to specify a molecule's optical rotation — the direction that the molecule rotates in polarized light. When a molecule is denoted dextrorotatory it is rotating the plane of polarized light clockwise and can also be denoted as (+). When it is denoted as levorotatory it is rotating the plane of polarized light counterclockwise and can also be denoted as (−).
The Latin words for left are laevus and sinister, and the word for right is dexter (or rectus in the sense of correct or virtuous). The English word right is a cognate of rectus. This is the origin of the D/L and R/S notations, and the employment of prefixes levo- and dextro- in common names.
The prefix ar-, from the Latin recto (right), is applied to the right-handed version; es-, from the Latin sinister (left), to the left-handed molecule. Example: ketamine, arketamine, esketamine. | 0 | Theoretical and Fundamental Chemistry |
Heterosynaptic plasticity (or also heterotropic modulation) is a change in synaptic strength that results from the activity of other neurons. Again, the plasticity can alter the number of vesicles or their replenishment rate or the relationship between calcium and vesicle release. Additionally, it could directly affect calcium influx. Heterosynaptic plasticity can also be postsynaptic in nature, affecting receptor sensitivity.
One example is again neurons of the sympathetic nervous system, which release noradrenaline, which, in addition, generates an inhibitory effect on presynaptic terminals of neurons of the parasympathetic nervous system. | 1 | Applied and Interdisciplinary Chemistry |
In 1905, Einstein proposed a theory of the photoelectric effect using a concept that light consists of tiny packets of energy known as photons or light quanta. Each packet carries energy that is proportional to the frequency of the corresponding electromagnetic wave. The proportionality constant has become known as the Planck constant. In the range of kinetic energies of the electrons that are removed from their varying atomic bindings by the absorption of a photon of energy , the highest kinetic energy is
Here, is the minimum energy required to remove an electron from the surface of the material. It is called the work function of the surface and is sometimes denoted or . If the work function is written as
the formula for the maximum kinetic energy of the ejected electrons becomes
Kinetic energy is positive, and is required for the photoelectric effect to occur. The frequency is the threshold frequency for the given material. Above that frequency, the maximum kinetic energy of the photoelectrons as well as the stopping voltage in the experiment rise linearly with the frequency, and have no dependence on the number of photons and the intensity of the impinging monochromatic light. Einstein's formula, however simple, explained all the phenomenology of the photoelectric effect, and had far-reaching consequences in the development of quantum mechanics. | 0 | Theoretical and Fundamental Chemistry |
Oxidation itself was first studied by Antoine Lavoisier, who defined it as the result of reactions with oxygen (hence the name). The term has since been generalized to imply a formal loss of electrons. Oxidation states, called oxidation grades by Friedrich Wöhler in 1835, were one of the intellectual stepping stones that Dmitri Mendeleev used to derive the periodic table. William B. Jensen gives an overview of the history up to 1938. | 0 | Theoretical and Fundamental Chemistry |
Many screens are analyzed using the image analysis software that accompanies the instrument, providing a turn-key solution. Third-party software alternatives are often used for particularly challenging screens or where a laboratory or facility has multiple instruments and wishes to standardize to a single analysis platform. Some instrument software provides bulk importing and exporting of images and data, for users who want to do such standardization on a single analysis platform without the use of third-party software, however. | 1 | Applied and Interdisciplinary Chemistry |
Inhibitors of protein AMPylation with inhibitory constant (K) ranging from 6 - 50 μM and at least 30-fold selectivity versus HypE have been discovered. | 1 | Applied and Interdisciplinary Chemistry |
Delayed nuclear radiation is a form of nuclear decay. When an isotope decays into a very short-lived isotope and then decays again to a relatively long-lived isotope, the products of the second decay are delayed. The short-lived isotope is usually a meta-stable nuclear isomer.
For example, gallium-73 decays via beta decay into germanium-73m2, which is short-lived (499ms). The germanium isotope emits two weak gamma rays and a conversion electron.
: → + 2 + ; → + (53.4 keV) + (13.3 keV) +
Because the middle isotope is so short-lived, the gamma rays are considered part of the gallium decay. Therefore, the above equations are combined.
However, since there is a short time delay between the beta decay and the high energy gamma emissions and the third and fourth gamma rays, it is said that the lower energy gamma rays are delayed.
Delayed gamma emissions are the most common form of delayed radiation, but are not the only form. It is common for the short-lived isotopes to have delayed emissions of various particles. In these cases, it is commonly called a beta-delayed emission. This is because the decay is delayed until a beta decay takes place. For instance, nitrogen-17 emits two beta-delayed neutrons after its primary beta emission. Just as in the above delayed gamma emission, the nitrogen is not the actual source of the neutrons, the source of the neurons is a short-lived isotope of oxygen. | 0 | Theoretical and Fundamental Chemistry |
I is one of seven long-lived fission products. It is primarily formed from the fission of uranium and plutonium in nuclear reactors. Significant amounts were released into the atmosphere by nuclear weapons testing in the 1950s and 1960s, by nuclear reactor accidents and by both military and civil reprocessing of spent nuclear fuel.
It is also naturally produced in small quantities, due to the spontaneous fission of natural uranium, by cosmic ray spallation of trace levels of xenon in the atmosphere, and by cosmic ray muons striking tellurium-130.
I decays with a half-life of 15.7 million years, with low-energy beta and gamma emissions, to stable xenon-129 (Xe). | 0 | Theoretical and Fundamental Chemistry |
The energy required to detach an electron in its lowest energy state from an atom or molecule of a gas with less net electric charge is called the ionization potential, or ionization energy. The nth ionization energy of an atom is the energy required to detach its nth electron after the first electrons have already been detached.
Each successive ionization energy is markedly greater than the last. Particularly great increases occur after any given block of atomic orbitals is exhausted of electrons. For this reason, ions tend to form in ways that leave them with full orbital blocks. For example, sodium has one valence electron in its outermost shell, so in ionized form it is commonly found with one lost electron, as . On the other side of the periodic table, chlorine has seven valence electrons, so in ionized form it is commonly found with one gained electron, as . Caesium has the lowest measured ionization energy of all the elements and helium has the greatest. In general, the ionization energy of metals is much lower than the ionization energy of nonmetals, which is why, in general, metals will lose electrons to form positively charged ions and nonmetals will gain electrons to form negatively charged ions. | 0 | Theoretical and Fundamental Chemistry |
Since the LUMOs of nontrigonal pnictogen compounds consist mainly of the vacant p orbitals of the pnictogen nuclei, they could undergo one-electron reduction to afford radical anions if the energy levels of LUMOs are appropriate. For a less sterically hindered compound, the generated radical anion readily dimerizes to form a dianion with a P-P bond. When a sterically encumbered tris-amide ligand is used, stable radical anions bearing T-shaped pnictogen nuclei can be isolated and characterized.
The oxidation of nontrigonal phosphorus compounds and transfer of halogen molecules to the phosphorus atoms to generate phosphoranes with phosphorus atoms in an oxidation state of +5 was achieved by various synthetic procedures. These dihalides are promising starting materials and potentially applicable for the generation of numerous secondary products, but only few reactions have been reported so far in the literature. Nontrigonal phosphorus compounds can also be oxidized by organic azide to yield phosphazenes. | 0 | Theoretical and Fundamental Chemistry |
Hydrogen abstraction generates radicals. To achieve this reaction, the C-H bond of the H-atom donor must weak, which is rarely the case in organic compounds. Allylic and especiall doubly allylic C-H bonds are prone to abstraction by O. This reaction is the basis of drying oils, such as linoleic acid derivatives. | 1 | Applied and Interdisciplinary Chemistry |
The Gibbs free energy of mixing, , must be negative for a blend to be miscible. According to Flory-Huggins theory, a revision of regular solution theory, the entropy change per mole of lattice sites of blending polymer 1 and polymer 2 is
, where ΔS is the change in entropy of mixing, R is the gas constant, Φ is the volume fraction of each polymer, and x is the number of segments of each polymer. x and x increase with higher degrees of polymerization and thus molecular weight. Since most useful polymers are high in molecular weight, the change in entropy experienced from the mixing of two large polymer chains is very low, and typically does not bring the Gibbs free energy low enough to constitute miscibility. | 0 | Theoretical and Fundamental Chemistry |
James Derek Birchall (7 October 1930 – 7 December 1995) was an English inorganic chemist, materials scientist, and inventor who spent most of his career working for Imperial Chemical Industries. He is known for his research on the health effects of exposure to silica and alumina. | 0 | Theoretical and Fundamental Chemistry |
Lucia V. Streng (November 6, 1909 – April 28, 1995) was a Russian Empire-born American chemist. She spent much of her career studying the noble gases and their properties, successfully synthesizing krypton difluoride. She and her husband, Alex G. Streng, both held positions at Temple University. | 0 | Theoretical and Fundamental Chemistry |
Gene knockdown by transfection of exogenous siRNA is often unsatisfactory because the effect is only transient, especially in rapidly dividing cells. This may be overcome by creating an expression vector for the siRNA. The siRNA sequence is modified to introduce a short loop between the two strands. The resulting transcript is a short hairpin RNA (shRNA), which can be processed into a functional siRNA by Dicer in its usual fashion. Typical transcription cassettes use an RNA polymerase III promoter (e.g., U6 or H1) to direct the transcription of small nuclear RNAs (snRNAs) (U6 is involved in RNA splicing; H1 is the RNase component of human RNase P). It is theorized that the resulting siRNA transcript is then processed by Dicer.
The gene knockdown efficiency can also be improved by using cell squeezing.
The activity of siRNAs in RNAi is largely dependent on its binding ability to the RNA-induced silencing complex (RISC). Binding of the duplex siRNA to RISC is followed by unwinding and cleavage of the sense strand with endonucleases. The remaining anti-sense strand-RISC complex can then bind to target mRNAs for initiating transcriptional silencing. | 1 | Applied and Interdisciplinary Chemistry |
After escaping the promoter and shedding most of the transcription factors for initiation, the polymerase acquires new factors for the next phase of transcription: elongation. Transcription elongation is a processive process. Double stranded DNA that enters from the front of the enzyme is unzipped to avail the template strand for RNA synthesis. For every DNA base pair separated by the advancing polymerase, one hybrid RNA:DNA base pair is immediately formed. DNA strands and nascent RNA chain exit from separate channels; the two DNA strands reunite at the trailing end of the transcription bubble while the single strand RNA emerges alone. | 1 | Applied and Interdisciplinary Chemistry |
Cyclization of an azomethine ylide with a carbonyl affords a spirocyclic oxazolidine, which loses CO to form a seven-membered ring. These high-utility decarboxylative multi-step reactions are common in azomethine ylide chemistry. | 0 | Theoretical and Fundamental Chemistry |
Phosphinooxazolines are able to influence both the enantioselectivity and regioselectivity of a range of metal catalysed reactions. In reactions involving symmetric transition states these properties work in concert to induce asymmetry and thus promote the formation of a single product. Enantioselectivity is controlled by the chirality of the ligand which is normally located on the oxazoline ring, however the P-centre may also be stereogenic. Regioselectivity is controlled by variety of steric and electronic factors the most important of which being a form of trans effect, in which atoms complexed trans to the P‑atom become more electrophilic than ones located trans to the N‑atom. This is caused by the P‑atom engaging in back bonding, as it is a π‑electron acceptor. | 0 | Theoretical and Fundamental Chemistry |
During the early 1800s, consumers preserved their food by storing food and ice purchased from ice harvesters in iceboxes. In 1803, Thomas Moore patented a metal-lined butter-storage tub which became the prototype for most iceboxes. These iceboxes were used until nearly 1910 and the technology did not progress. In fact, consumers that used the icebox in 1910 faced the same challenge of a moldy and stinky icebox that consumers had in the early 1800s.
General Electric (GE) was one of the first companies to overcome these challenges. In 1911, GE released a household refrigeration unit that was powered by gas. The use of gas eliminated the need for an electric compressor motor and decreased the size of the refrigerator. However, electric companies that were customers of GE did not benefit from a gas-powered unit. Thus, GE invested in developing an electric model. In 1927, GE released the Monitor Top, the first refrigerator to run on electricity.
In 1930, Frigidaire, one of GE's main competitors, synthesized Freon. With the invention of synthetic refrigerants based mostly on a chlorofluorocarbon (CFC) chemical, safer refrigerators were possible for home and consumer use. Freon led to the development of smaller, lighter, and cheaper refrigerators. The average price of a refrigerator dropped from $275 to $154 with the synthesis of Freon. This lower price allowed ownership of refrigerators in American households to exceed 50% by 1940. Freon is a trademark of the DuPont Corporation and refers to these CFCs, and later hydro chlorofluorocarbon (HCFC) and hydro fluorocarbon (HFC), refrigerants developed in the late 1920s. These refrigerants were considered — at the time — to be less harmful than the commonly-used refrigerants of the time, including methyl formate, ammonia, methyl chloride, and sulfur dioxide. The intent was to provide refrigeration equipment for home use without danger. These CFC refrigerants answered that need. In the 1970s, though, the compounds were found to be reacting with atmospheric ozone, an important protection against solar ultraviolet radiation, and their use as a refrigerant worldwide was curtailed in the Montreal Protocol of 1987. | 0 | Theoretical and Fundamental Chemistry |
The discoveries of the 19th century, both the successes and failures, set the stage for the emergence of quantum mechanics. | 1 | Applied and Interdisciplinary Chemistry |
The Farmers General held a monopoly of the production, import and sale of tobacco in France, and the taxes they levied on tobacco brought revenues of 30 million livres a year. This revenue began to fall because of a growing black market in tobacco that was smuggled and adulterated, most commonly with ash and water. Lavoisier devised a method of checking whether ash had been mixed in with tobacco: "When a spirit of vitriol, aqua fortis or some other acid solution is poured on ash, there is an immediate very intense effervescent reaction, accompanied by an easily detected noise." Lavoisier also noticed that the addition of a small amount of ash improved the flavour of tobacco. Of one vendor selling adulterated goods, he wrote "His tobacco enjoys a very good reputation in the province... the very small proportion of ash that is added gives it a particularly pungent flavour that consumers look for. Perhaps the Farm could gain some advantage by adding a bit of this liquid mixture when the tobacco is fabricated." Lavoisier also found that while adding a lot of water to bulk the tobacco up would cause it to ferment and smell bad, the addition of a very small amount improved the product. Thereafter the factories of the Farmers General added, as he recommended, a consistent 6.3% of water by volume to the tobacco they processed. To allow for this addition, the Farmers General delivered to retailers seventeen ounces of tobacco while only charging for sixteen. To ensure that only these authorised amounts were added, and to exclude the black market, Lavoisier saw to it that a watertight system of checks, accounts, supervision and testing made it very difficult for retailers to source contraband tobacco or to improve their profits by bulking it up. He was energetic and rigorous in implementing this, and the systems he introduced were deeply unpopular with the tobacco retailers across the country. This unpopularity was to have consequences for him during the French Revolution. | 1 | Applied and Interdisciplinary Chemistry |
In the presence of the group 3 homoleptic catalyst Y[N(SiMe)], triphenylphosphonium methylide can be coupled with phenylsilane. This reaction produces H gas as a byproduct, and forms a silyl-stabilised ylide. | 0 | Theoretical and Fundamental Chemistry |
Counterflow centrifugal elutriation (CCE) is a liquid clarification technique. This method enables scientists to separate different cells with different sizes. Since cell size is correlated with cell cycle stages this method also allows the separation of cells at different stages of the cell cycle. | 0 | Theoretical and Fundamental Chemistry |
After the steam is conditioned by the drying equipment inside the drum, it is piped from the upper drum area into an elaborate set up of tubing in different areas of the boiler, the areas known as superheater and reheater. The steam vapor picks up energy and is superheated above the saturation temperature. The superheated steam is then piped through the main steam lines to the valves of the high-pressure turbine. | 1 | Applied and Interdisciplinary Chemistry |
Both prokaryotic and eukarotic genomes are organized into large loops of protein-bound DNA. In eukaryotes, the bases of the loops are called scaffold attachment regions (SARs) and they consist of stretches of DNA that bind an RNA/protein complex to stabilize the loop. There are about 100,000 loops in the human genome and each one consists of about 100 bp of DNA. The total amount of DNA devoted to SARs accounts for about 0.3% of the human genome. | 1 | Applied and Interdisciplinary Chemistry |
The Center for Pharmaceutical Research and Innovation (CPRI) is a University of Kentucky-based research center established by the University of Kentucky College of Pharmacy in 2012 to facilitate academic translational research and drug discovery/drug development. The UK CPRI specializes in natural product-based drug discovery from microbes found within unique environments including underground and surface coal mines, acid mine drainage and mine reclamation sites, thermal vents associated with underground coal mine fires (see coal seam fire) and deep-well drilling for carbon sequestration. CPRI also provides core support for medicinal chemistry, assay development and screening, rational drug design, computational chemistry, and ADMET. The Center collaborates with investigators focused on drug discovery or development research in the areas of cancer, drug and alcohol addiction, cardiovascular disease, infectious disease, regenerative medicine and neurodegenerative disease. | 1 | Applied and Interdisciplinary Chemistry |
A line source or sink of strength ( for source and for sink) is given by the potential
where in fact is the volume flux per unit length across a surface enclosing the source or sink. The velocity field in polar coordinates are
i.e., a purely radial flow. | 1 | Applied and Interdisciplinary Chemistry |
In arid areas, check dams are often built to increase groundwater recharge in a process called managed aquifer recharge. Winter runoff thus can be stored in aquifers, from which the water can be withdrawn during the dry season for irrigation, livestock watering, and drinking water. This is particularly useful for small settlements located far from a large urban center as check dams require less reliance on machinery, funding, or advanced knowledge compared to large-scale dam implementation.
Check dams can be used in combination with limans to stop and collect surface runoff water. | 1 | Applied and Interdisciplinary Chemistry |
Cleve joined the Royal Swedish Academy of Sciences in 1871. He received a Davy Medal in 1894 and 1904.
The mineral cleveite is named for Cleve. | 1 | Applied and Interdisciplinary Chemistry |
The mechanisms of tardigrade desiccation protection were originally thought to result from high levels of the sugar trehalose. Trehalose is used by organisms like yeast to avoid desiccation in dry environments by working with heat shock proteins to keep desiccation-sensitive proteins in solution. However, while tardigrades can accumulate small levels of trehalose, the levels are insufficient to provide protection from extreme conditions. Other molecules which help certain organisms avoid cellular desiccation include late embryogenesis abundant proteins, which provide protection to embryonic cotton seeds. Certain proteins actually responsible for the tardigrade's hardiness, including the cytoplasmic and secreted abundant heat soluble proteins, were discovered when searching for late embryogenesis abundant proteins in tardigrades.
One strategy used by the tardigrade to survive in dry environments is anhydrobiosis. Anhydrobiosis is a process in which an organism can lose nearly all of its water and enter an ametabolic state. | 1 | Applied and Interdisciplinary Chemistry |
There were four named penicillins at the time penicillin V was discovered (penicillins I, II, III, IV), however, Penicillin V was named "V" for Vertraulich (German for confidential); it was not named for the Roman numeral "5".
Penicillin VK is the potassium salt of penicillin V (K is the chemical symbol for potassium). | 0 | Theoretical and Fundamental Chemistry |
Gel permeation chromatography (GPC) is a type of size-exclusion chromatography (SEC), that separates high molecular weight or colloidal analytes on the basis of size or diameter, typically in organic solvents. The technique is often used for the analysis of polymers. As a technique, SEC was first developed in 1955 by Lathe and Ruthven. The term gel permeation chromatography can be traced back to J.C. Moore of the Dow Chemical Company who investigated the technique in 1964. The proprietary column technology was licensed to Waters Corporation, who subsequently commercialized this technology in 1964. GPC systems and consumables are now also available from a number of manufacturers. It is often necessary to separate polymers, both to analyze them as well as to purify the desired product.
When characterizing polymers, it is important to consider their size distribution and dispersity (Đ) as well their molecular weight. Polymers can be characterized by a variety of definitions for molecular weight including the number average molecular weight (M), the weight average molecular weight (M) (see molar mass distribution), the size average molecular weight (M), or the viscosity molecular weight (M). GPC allows for the determination of Đ as well as M and, based on other data, the M, M, and M can be determined. | 0 | Theoretical and Fundamental Chemistry |
The compound cis-[Pt(NH)Cl] was first described by Italian chemist Michele Peyrone in 1845, and known for a long time as Peyrones salt. The structure was deduced by Alfred Werner in 1893. In 1965, Barnett Rosenberg, Van Camp et al. of Michigan State University discovered that electrolysis of platinum electrodes generated a soluble platinum complex which inhibited binary fission in Escherichia coli (E. coli) bacteria. Although bacterial cell growth continued, cell division was arrested, the bacteria growing as filaments up to 300 times their normal length. The octahedral Pt(IV) complex cis-[PtCl(NH)], but not the trans isomer, was found to be effective at forcing filamentous growth of E. coli cells. The square planar Pt(II) complex, cis-[PtCl(NH)] turned out to be even more effective at forcing filamentous growth. This finding led to the observation that cis'-[PtCl(NH)] was indeed highly effective at regressing the mass of sarcomas in rats. Confirmation of this discovery, and extension of testing to other tumour cell lines launched the medicinal applications of cisplatin. Cisplatin was approved for use in testicular and ovarian cancers by the U.S. Food and Drug Administration on 19 December 1978. and in the UK (and in several other European countries) in 1979.
Cisplatin was the first to be developed.
In 1983 pediatric oncologist Roger Packer began incorporating cisplatin into adjuvant chemotherapy for the treatment of childhood medulloblastoma. The new protocol that he developed led to a marked increase in disease-free survival rates for patients with medulloblastoma, up to around 85%. The Packer Protocol has since become a standard treatment for medulloblastoma. Likewise, cisplatin has been found to be particularly effective against testicular cancer, where its use improved the cure rate from 10% to 85%.
Recently, some researchers have investigated at the preclinical level new forms of cisplatin prodrugs in combination with nanomaterials in order to localize the release of the drug in the target. | 1 | Applied and Interdisciplinary Chemistry |
There are some common types of spectrophotometers include:
UV-vis spectrophotometer: Measures light absorption in UV and visible ranges (200-800 nm). Used for quantification of many inorganic and organic compounds.
1. Infrared spectrophotometer: Measures infrared light absorption, allowing identification of chemical bonds and functional groups.
2. Atomic absorption spectrophotometer (AAS): Uses absorption of light by vaporized analyte atoms to determine concentrations of metals and metalloids.
3. Fluorescence spectrophotometer: Measures intensity of fluorescent light emitted from samples after excitation. Allows highly sensitive analysis of samples with native or induced fluorescence.
4. Colorimeter: Simple spectrophotometers used to measure light absorption for colorimetric assays and tests. | 0 | Theoretical and Fundamental Chemistry |
Porous implants are characterized by the presence of voids in the metallic or ceramic matrix. Voids can be regular, such as in additively manufactured (AM) lattices, or stochastic, such as in gas-infiltrated production processes. The reduction in the modulus of the implant follows a complex nonlinear relationship dependent on the volume fraction of base material and morphology of the pores.
Experimental models exist to predict the range of modulus that stochastic porous material may take. Above 10% vol. fraction porosity, models begin to deviate significantly. Different models, such as the rule of mixtures for low porosity, two-material matrices have been developed to describe mechanical properties.
AM lattices have more predictable mechanical properties compared to stochastic porous materials and can be tuned such that they have favorable directional mechanical properties. Variables such as strut diameter, strut shape, and number of cross-beams can have a dramatic effect on loading characteristics of the lattice. AM has the ability to fine-tune the lattice spacing to within a much smaller range than stochastically porous structures, enabling the future cell-development of specific cultures in tissue engineering. | 1 | Applied and Interdisciplinary Chemistry |
Pipes, fittings, valves, and accessories make up a plastic pressure pipe system. The range of pipe diameters for each pipe system does vary. However, the size ranges from and . Pipes are extruded and are generally available in: , , , and straight lengths and , , , and coils for LDPE and HDPE.
Pipe fittings are moulded and come in many sizes: tee 90° equal (straight and reducing), tee 45°, cross equal, elbow 90° (straight and reducing), elbow 45°, short radius bend 90° socket/coupler (straight and reducing), union, end caps, reducing bush, and stub, full face, and blanking flanges.
Valves are moulded and also come in many types: ball valves (also multiport valve), butterfly valves, spring-, ball-, and swing-check non-return valves, diaphragm valves, knife gate valve, globe valves and pressure relief/reduction valves.
Accessories are solvents, cleaners, glues, clips, backing rings, and gaskets. | 1 | Applied and Interdisciplinary Chemistry |
Floriana completed her Bachelor of Science at University of Bucharest. She continued to read her Master of Science degree at University of Bucharest and successfully completed it in 1989 before moving to the Institute of Physical Chemistry of the Romanian Academy to read her Doctor of Philosophy degree in transition metal chemistry, which was completed in 1997 and was supervised by Prof. Marius Andruh and Prof. Luminita Patron. | 0 | Theoretical and Fundamental Chemistry |
This method can be used to detect co-binding of two factors to the same genomic locus. The Dam methylase may be expressed in two halves which are fused to different proteins of interest. When both proteins bind to the same region of DNA, the Dam enzyme is reconstituted and is able to methylate the surrounding GATC sites. | 1 | Applied and Interdisciplinary Chemistry |
In contrast to purple bacteria and other bacteria performing anoxygenic photosynthesis, thylakoid membranes of cyanobacteria are not continuous with the plasma membrane but are separate compartments. The photosynthetic machinery is embedded in the thylakoid membranes, with phycobilisomes acting as light-harvesting antennae attached to the membrane, giving the green pigmentation observed (with wavelengths from 450 nm to 660 nm) in most cyanobacteria.
While most of the high-energy electrons derived from water are used by the cyanobacterial cells for their own needs, a fraction of these electrons may be donated to the external environment via electrogenic activity. | 0 | Theoretical and Fundamental Chemistry |
Magnetic inequivalence may occur with HC-CH fragments that are subdivided into two groups of two in either geminal relationships via a mirror plane along the C-C bond, i.e. HHC-CHH, or in vicinal relationships via a mirror plane bisecting the C-C bond, i.e. in HHC-CHH, or via a rotational axis of symmetry (a C-axis), i.e. HHC-CHH. The coupling constants then differ because of geometry (cis vs. trans) or connectivity (2-bond vs. 3-bond) and the level of complexity will depend on the differences. Conformational dynamics may reduce or even obliterate the difference between cis and trans couplings, if fast compared to the NMR timescale. There may also be additional couplings to other nuclei.
The ethylene fragment in 2-substituted dioxolanes can thus show a high level of complexity if the substituent is large. Symmetrical norbornanes and similarly rigid compounds (e.g. 7-oxabicyclo[2.2.1]heptane) also show complex signals for the ethylene fragments, made more complicated by additional splitting by the bridgehead protons. Reich gives several additional examples of magnetic inequivalence in acyclic and cyclic systems containing HC-CH fragments. | 0 | Theoretical and Fundamental Chemistry |
More so than thiophenol, benzeneselenol is easily oxidized by air. The facility of this reaction reflects the weakness of the Se-H bond, bond dissociation energy of which is estimated to be between 67 and 74 kcal/mol. In contrast, the S-H BDE for thiophenol is near 80 kcal/mol. The product is diphenyl diselenide as shown in this idealized equation:
The presence of the diselenide in benzeneselenol is indicated by a yellow coloration. The diselenide can be converted back to the selenol by reduction followed by acidification of the resulting .
PhSeH is acidic with a pK of 5.9. Thus at neutral pH, it is mostly ionized:
It is approximately seven times more acidic than the related thiophenol. Both compounds dissolve in water upon the addition of base. The conjugate base is , a potent nucleophile. | 0 | Theoretical and Fundamental Chemistry |
Protons can also interact with the nucleus of the atoms in the sample through elastic collisions, Rutherford backscattering, often repelling the proton at angles close to 180 degrees. The backscatter give information on the sample thickness and composition. The bulk sample properties allow for the correction of X-ray photon loss within the sample. | 0 | Theoretical and Fundamental Chemistry |
The stereoelectronic effect influences the thermodynamics of equilibrium. For example, the following equilibrium could be achieved via a cascade of pericyclic reactions.
Despite very similar structures, one of the two isomers is strongly favored over the other because of a stereoelectronic effect. Since the σ* orbital adjacent to the electron-withdrawing carbonyl group is lower in energy and is therefore a better acceptor than the σ* orbital adjacent to the methoxy, the isomer in which the n lone pair is able to donate into this lower-energy antibonding orbital will be stabilized (orbital interaction illustrated).
Another example of the preference in the equilibrium within the area of pericyclic reaction is shown below. The stereoelectronic effect that affect the equilibrium is the interaction between the delocalized “banana bonds” and the empty p orbital on the boron atom. | 0 | Theoretical and Fundamental Chemistry |
As a result of low densities and speeds of atoms achieved by optical cooling, the mean free path in a ball of MOT cooled atoms is very long, and atoms may be treated as ballistic. This is useful for quantum information experiments where it is necessary to have long coherence times (the time an atom spends in a defined quantum state). Because of the continuous cycle of absorption and spontaneous emission, which causes decoherence, any quantum manipulation experiments must be performed with the MOT beams turned off. In this case, it is common to stop the expansion of the gases during quantum information experiments by loading the cooled atoms into a dipole trap.
A magneto-optical trap is usually the first step to achieving Bose–Einstein condensation. Atoms are cooled in a MOT down to a few times the recoil limit, and then evaporatively cooled which lowers the temperature and increases the density to the required phase space density.
A MOT of Cs was used to make some of the best measurements of CP violation.
MOTs are used in a number of quantum technologies (i.e. cold atom gravity gradiometers) and have been deployed on several platforms (i.e. UAVs) and in several environments (i.e. down boreholes ). | 0 | Theoretical and Fundamental Chemistry |
The ELP can be conjugated to a functional group that can bind to a protein of interest. At temperatures below the T the ELP will bind to the ligand in its linear form. In this linear state, the ELP-protein complex cannot easily be distinguished from the extraneous proteins in the solution. However, once the solution is heated to a temperature exceeding the T the ELP will form spherical clumps. These clumps will then settle to the bottom of the solution tube following centrifugation, carrying the protein of interest. The proteins that are not needed will be found in the supernatant, which can be physically separated from the spherical aggregates. To ensure that there are few impurities in the ELP-protein complex isolated, the solution can be cooled below the T enabling the ELPs to once again assume their linear structure. From this point, hot and cold centrifugation cycles can be repeated, and then the protein of interest can be eluted from the ELPs via the addition of a salt. | 0 | Theoretical and Fundamental Chemistry |
Concentration depends on the variation of the volume of the solution with temperature, due mainly to thermal expansion. | 0 | Theoretical and Fundamental Chemistry |
*Atkins, P.W. (1978). Physical Chemistry Oxford University Press
*Trevor Palmer (2001) Enzymes: biochemistry, biotechnology and clinical chemistry Chichester Horwood Publishing | 0 | Theoretical and Fundamental Chemistry |
Hidden stops are non-stop codons that would be read as stop codons if they were frameshifted +1 or −1. These prematurely terminate translation if the corresponding frame-shift (such as due to a ribosomal RNA slip) occurs before the hidden stop. It is hypothesised that this decreases resource wastage on nonfunctional proteins and the production of potential cytotoxins. Researchers at Louisiana State University propose the ambush hypothesis, that hidden stops are selected for. Codons that can form hidden stops are used in genomes more frequently compared to synonymous codons that would otherwise code for the same amino acid. Unstable rRNA in an organism correlates with a higher frequency of hidden stops.
However, this hypothesis could not be validated with a larger data set.
Stop-codons and hidden stops together are collectively referred as stop-signals. Researchers at University of Memphis found that the ratios of the stop-signals on the three reading frames of a genome (referred to as translation stop-signals ratio or TSSR) of genetically related bacteria, despite their great differences in gene contents, are much alike. This nearly identical genomic-TSSR value of genetically related bacteria may suggest that bacterial genome expansion is limited by their unique stop-signals bias of that bacterial species. | 1 | Applied and Interdisciplinary Chemistry |
When the cost of producing slaves became too high to justify slave labourers for the many mines throughout the empire around the second century, a system of indentured servitude was introduced for convicts. In 369 AD, a law was reinstated due to the closure of many deep mines; the emperor Hadrian had previously given the control of mines to private employers, so that workers were hired rather than working out of force. Through the institution of this system profits increased (Shepard 1993). In the case of Noricum, there is archaeological evidence of freemen labour in the metal trade and extraction through graffiti on mine walls. In this province, many men were given Roman citizenship for their efforts contributing to the procurement of metal for the empire. Both privately owned and government run mines were in operation simultaneously (Shepard 1993). | 1 | Applied and Interdisciplinary Chemistry |
Ethers () consist of an oxygen atom between the two attached carbon chains. The shorter of the two chains becomes the first part of the name with the -ane suffix changed to -oxy, and the longer alkane chain becomes the suffix of the name of the ether. Thus, is methoxymethane, and is methoxyethane (not ethoxymethane). If the oxygen is not attached to the end of the main alkane chain, then the whole shorter alkyl-plus-ether group is treated as a side-chain and prefixed with its bonding position on the main chain. Thus is 2-methoxypropane.
Alternatively, an ether chain can be named as an alkane in which one carbon is replaced by an oxygen, a replacement denoted by the prefix "oxa". For example, could also be called 2-oxabutane, and an epoxide could be called oxacyclopropane. This method is especially useful when both groups attached to the oxygen atom are complex. | 0 | Theoretical and Fundamental Chemistry |
Zinc chloride is used as a catalyst or reagent in diverse reactions conducted on an industrial scale. The partial hydrolysis of benzal chloride in the presence of zinc chloride is the main route to benzoyl chloride. It serves as a catalyst for the production of methylene-bis(dithiocarbamate).
The combination of hydrochloric acid and , known as the "Lucas reagent", is effective for the preparation of alkyl chlorides from alcohols. Similar reactions are the basis of industrial routes from methanol and ethanol respectively to methyl chloride and ethyl chloride. | 0 | Theoretical and Fundamental Chemistry |
A materials recovery facility, materials reclamation facility, materials recycling facility or multi re-use facility (MRF, pronounced "murf") is a specialized plant that receives, separates and prepares recyclable materials for marketing to end-user manufacturers. Generally, there are two different types: clean and dirty materials recovery facilities. | 1 | Applied and Interdisciplinary Chemistry |
Benzene is an organic chemical compound with the molecular formula CH. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon.
Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals. Due to the cyclic continuous pi bonds between the carbon atoms, benzene is classed as an aromatic hydrocarbon. Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma of gasoline. It is used primarily as a precursor to the manufacture of chemicals with more complex structures, such as ethylbenzene and cumene, of which billions of kilograms are produced annually. Although benzene is a major industrial chemical, it finds limited use in consumer items because of its toxicity. Benzene is a volatile organic compound.
Benzene is classified as a carcinogen.[https://emergency.cdc.gov/agent/benzene/basics/facts.asp] | 1 | Applied and Interdisciplinary Chemistry |
Krypton-85 is produced in small quantities by the interaction of cosmic rays with stable krypton-84 in the atmosphere. Natural sources maintain an equilibrium inventory of about 0.09 PBq in the atmosphere. | 0 | Theoretical and Fundamental Chemistry |
The Eulerian form of the Cauchy momentum equation for a fluid is
for isotropic pressure , where is fluid velocity, the fluid density, and the gravitational acceleration. The Eulerian rate of change of momentum in direction at a point is thus (using Einstein notation):
Substituting the conservation of mass, expressed as
this is equivalent to
using the product rule and the Kronecker delta . The first term in the brackets is the isotropic thermal pressure, and the second is the ram pressure.
In this context, ram pressure is momentum transfer by advection (flow of matter carrying momentum across a surface into a body). The mass per unit second flowing into a volume bounded by a surface is
and the momentum per second it carries into the body is
equal to the ram pressure term. This discussion can be extended to drag forces; if all matter incident upon a surface transfers all its momentum to the volume, this is equivalent (in terms of momentum transfer) to the matter entering the volume (the context above). On the other hand, if only velocity perpendicular to the surface is transferred, there are no shear forces, and the effective pressure on that surface increases by
where is the velocity component perpendicular to the surface. | 1 | Applied and Interdisciplinary Chemistry |
DNA in solution does not take a rigid structure but is continually changing conformation due to thermal vibration and collisions with water molecules, which makes classical measures of rigidity impossible to apply. Hence, the bending stiffness of DNA is measured by the persistence length, defined as:
This value may be directly measured using an atomic force microscope to directly image DNA molecules of various lengths. In an aqueous solution, the average persistence length is 46–50 nm or 140–150 base pairs (the diameter of DNA is 2 nm), although can vary significantly. This makes DNA a moderately stiff molecule.
The persistence length of a section of DNA is somewhat dependent on its sequence, and this can cause significant variation. The variation is largely due to base stacking energies and the residues which extend into the minor and major grooves. | 0 | Theoretical and Fundamental Chemistry |
This theoretical paradox is directed at the then-mainstream strand of belief in a classical view of a sempiternal universe, whereby its matter is postulated as everlasting and having always been recognisably the universe. Heat death paradox is born of a paradigm resulting from fundamental ideas about the cosmos. It is necessary to change the paradigm to resolve the paradox.
The paradox was based upon the rigid mechanical point of view of the second law of thermodynamics postulated by Rudolf Clausius and Lord Kelvin, according to which heat can only be transferred from a warmer to a colder object. It notes: if the universe were eternal, as claimed classically, it should already be cold and isotropic (its objects should have the same temperature, and the distribution of matter or radiation should be even). Kelvin compared the universe to a clock that runs slower and slower, constantly dissipating energy in impalpable heat, although he was unsure whether it would stop for ever (reach thermodynamic equilibrium). According to this model, the existence of usable energy, which can be used to perform work and produce entropy, means that the clock has not stopped - since a conversion of heat in mechanical energy (which Kelvin called a rejuvenating universe scenario) is not contemplated.
According to the laws of thermodynamics, any hot object transfers heat to its cooler surroundings, until everything is at the same temperature. For two objects at the same temperature as much heat flows from one body as flows from the other, and the net effect is no change. If the universe were infinitely old, there must have been enough time for the stars to cool and warm their surroundings. Everywhere should therefore be at the same temperature and there should either be no stars, or everything should be as hot as stars. The universe should thus achieve, or asymptotically tend to, thermodynamic equilibrium, which corresponds to a state where no thermodynamic free energy is left, and therefore no further work is possible: this is the heat death of the universe, as predicted by Lord Kelvin in 1852. The average temperature of the cosmos should also asymptotically tend to Kelvin Zero, and it is possible that a maximum entropy state will be reached. | 0 | Theoretical and Fundamental Chemistry |
Jelly-falls are marine carbon cycling events whereby gelatinous zooplankton, primarily cnidarians, sink to the seafloor and enhance carbon and nitrogen fluxes via rapidly sinking particulate organic matter. These events provide nutrition to benthic megafauna and bacteria. Jelly-falls have been implicated as a major “gelatinous pathway” for the sequestration of labile biogenic carbon through the biological pump. These events are common in protected areas with high levels of primary production and water quality suitable to support cnidarian species. These areas include estuaries and several studies have been conducted in fjords of Norway. | 0 | Theoretical and Fundamental Chemistry |
Several models attempt to account for the bulk properties of water by assuming that they are dominated by cluster formation within the liquid. According to the quantum cluster equilibrium (QCE) theory of liquids, n=8 clusters dominate the liquid water bulk phase, followed by n=5 and n=6 clusters. Near the triple point, the presence of an n=24 cluster is invoked. In another model, bulk water is built up from a mixture of hexamer and pentamer rings containing cavities capable of enclosing small solutes. In yet another model an equilibrium exists between a cubic water octamer and two cyclic tetramers. However, no model yet has reproduced the experimentally-observed density maximum of water as a function of temperature. | 0 | Theoretical and Fundamental Chemistry |
Effective public shelters can be the middle floors of some tall buildings or parking structures, or below ground level in most buildings with more than 10 floors. The thickness of the upper floors must form an effective shield, and the windows of the sheltered area must not view fallout-covered ground that is closer than 1.5 km (1 mi). One of Switzerland's solutions is to use road tunnels passing through the mountains, with some of these shelters being able to protect tens of thousands.
Fallout shelters are not always underground. Above ground buildings with walls and roofs dense enough to afford a meaningful protection factor can be used as a fallout shelter. | 0 | Theoretical and Fundamental Chemistry |
In oceanic biogeochemistry, the continental shelf pump is proposed to operate in the shallow waters of the continental shelves, acting as a mechanism to transport carbon (as either dissolved or particulate material) from surface waters to the interior of the adjacent deep ocean. | 0 | Theoretical and Fundamental Chemistry |
The use of alkyllithiums as strong bases has not been extensively studied, and have been unreliable for deprotonation of precursor salts. With non-aromatic salts, n-BuLi and PhLi can act as nucleophiles whilst t-BuLi can on occasion act as a source of hydride, reducing the salt with the generation of isobutene: | 0 | Theoretical and Fundamental Chemistry |
The internal energy is given by the energetic equation of state,
where is an arbitrary constant of integration.
Now in order for to be an exact differential, namely that be continuous with continuous partial derivatives, its second mixed partial derivatives must also be equal, . Then with this condition can be written simply as . Differentiating for the vdW equation gives , so . Consequently for a vdW fluid exactly as it is for an ideal gas. To keep things simple it is regarded as a constant here, with a number. Then both integrals can be easily evaluated and the result is
This is the energetic equation of state for a perfect vdW fluid. By making a dimensional analysis (what might be called extending the principle of corresponding states to other thermodynamic properties) it can be written simply in reduced form as
where and C is a dimensionless constant. | 0 | Theoretical and Fundamental Chemistry |
Low levels of vitamin D in pregnancy are associated with gestational diabetes, pre-eclampsia, and small (for gestational age) infants. Although taking vitamin D supplements during pregnancy raises blood levels of vitamin D in the mother at term, the full extent of benefits for the mother or baby is unclear. Pregnant women who take an adequate amount of vitamin D during gestation may experience a lower risk of pre-eclampsia and positive immune effects. Vitamin D supplementation is also likely to reduce the risk of gestational diabetes, undersized babies and of their poor rate of growth. Pregnant women often do not take the recommended amount of vitamin D. | 1 | Applied and Interdisciplinary Chemistry |
Formerly, the genus , belonging to the Thymelaeaceae, was generally considered to be the original plant, namely either L., or L. or L. But in 1879 W. Dymock was able to prove that at least the Persian sarcocolla is the product of what he called Dym. (Leguminosae). Widely known in antiquity, the drug practically disappeared from the European store of medicines, but, according to Meyerhof, it remained still well known in North Africa and Asia, especially in the drug market in Cairo. | 1 | Applied and Interdisciplinary Chemistry |
Quantum efficiency (QE) is the fraction of photon flux that contributes to the photocurrent in a photodetector or
a pixel. Quantum efficiency is one of the most important parameters used to evaluate the quality of a detector and is often called the spectral response to reflect its wavelength dependence. It is defined as the number of signal electrons created per incident photon. In some cases it can exceed 100% (i.e. when more than one electron is created per incident photon). | 0 | Theoretical and Fundamental Chemistry |
The term or is known as the Coulomb or electrostatic term.
The basis for this term is the electrostatic repulsion between protons. To a very rough approximation, the nucleus can be considered a sphere of uniform charge density. The potential energy of such a charge distribution can be shown to be
where Q is the total charge, and R is the radius of the sphere. The value of can be approximately calculated by using this equation to calculate the potential energy, using an empirical nuclear radius of and Q = Ze. However, because electrostatic repulsion will only exist for more than one proton, becomes :
where now the electrostatic Coulomb constant is
Using the fine-structure constant, we can rewrite the value of as
where is the fine-structure constant, and is the radius of a nucleus, giving to be approximately 1.25 femtometers. is the proton reduced Compton wavelength, and is the proton mass. This gives an approximate theoretical value of 0.691 MeV, not far from the measured value. | 0 | Theoretical and Fundamental Chemistry |
Engine oil is filtered to remove impurities. Filtration of oil is normally done with volume filtration. Filter papers for lubrication oils are impregnated to resist high temperatures. | 0 | Theoretical and Fundamental Chemistry |
Main article smFRET.
In single-molecule fluorescence resonance energy transfer, the molecule is labeled in (at least) two places. A laser beam is focused on the molecule exciting the first probe. When this probe relaxes and emits a photon, it has a chance of exciting the other probe. The efficiency of the absorption of the photon emitted from the first probe in the second probe depends on the distance between these probes. Since the distance changes with time, this experiment probes the internal dynamics of the molecule. | 0 | Theoretical and Fundamental Chemistry |
Ff phages (for F specific filamentous phages) is a group of almost identical filamentous phage (genus Inovirus) including phages f1, fd, M13 and ZJ/2, which infect bacteria bearing the F fertility factor. The virion (virus particle) is a flexible filament measuring about 6 by 900 nm, comprising a cylindrical protein tube protecting a single-stranded circular DNA molecule at its core. The phage codes for only 11 gene products, and is one of the simplest viruses known. It has been widely used to study fundamental aspects of molecular biology. George Smith and Greg Winter used f1 and fd for their work on phage display for which they were awarded a share of the 2018 Nobel Prize in Chemistry. Early experiments on Ff phages used M13 to identify gene functions, and M13 was also developed as a cloning vehicle, so the name M13 is sometimes used as an informal synonym for the whole group of Ff phages. | 1 | Applied and Interdisciplinary Chemistry |
Clinical chemistry (also known as chemical pathology, clinical biochemistry or medical biochemistry) is a division in medical laboratory sciences focusing on qualitative tests of important compounds, referred to as analytes or markers, in bodily fluids and tissues using analytical techniques and specialized instruments. This interdisciplinary field includes knowledge from medicine, biology, chemistry, biomedical engineering, informatics, and an applied form of biochemistry (not to be confused with medicinal chemistry, which involves basic research for drug development).
The discipline originated in the late 19th century with the use of simple chemical reaction tests for various components of blood and urine. In the many decades since, clinical chemists use automated analyzer in many clinical laboratories, which does experimental techniques ranging from pipetting specimens and specimen labelling to advanced measurement techniques such as spectrometry, chromatography, photometry, potentiometry, etc. These instruments provide different results that help identify uncommon analytes, changes in light and electronic voltage properties of naturally-occurring analytes such as enzymes, ions, electrolytes, and their concentrations, all of which are important for diagnosing diseases.
Blood and urine are the most common test specimens clinical chemists or medical laboratory scientists collect for clinical routine tests, with a main focus on serum and plasma in blood. There are now many blood tests and clinical urine tests with extensive diagnostic capabilities. Some clinical tests require clinical chemists to process the specimen before testing. Clinical chemists and medical laboratory scientists serve as the interface between the laboratory side and the clinical practice, providing suggestions to physicians on which test panel to order and interpret any irregularities in test results that reflect on the patients health status and organ system functionality. This allows healthcare providers to make more accurate evaluation of a patients health and to diagnose disease, predicting the progression of a disease (prognosis), screening, and monitoring the treatment's efficiency in a timely manner. The type of test required dictates what type of sample is used. | 1 | Applied and Interdisciplinary Chemistry |
;Acuminate: Coming to a sharp, narrow, prolonged point.
;Acute: Coming to a sharp, but not prolonged point.
;Auriculate: Ear-shaped.
;Cordate: Heart-shaped with the notch towards the stalk.
;Cuneate: Wedge-shaped.
;Hastate: Shaped like an halberd and with the basal lobes pointing outward.
;Oblique: Slanting.
;Reniform: Kidney-shaped but rounder and broader than long.
;Rounded: Curving shape.
;Sagittate: Shaped like an arrowhead and with the acute basal lobes pointing downward.
;Truncate: Ending abruptly with a flat end, that looks cut off. | 0 | Theoretical and Fundamental Chemistry |
Cynthia Larive is an American scientist and academic administrator serving as the chancellor of University of California, Santa Cruz. Larives research focuses on nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry. She was previously a professor of chemistry and provost and executive vice chancellor at the University of California, Riverside. She is a fellow of AAAS, IUPAC and ACS, associate editor for the ACS journal Analytical Chemistry' and editor of the Analytical Sciences Digital Library. | 0 | Theoretical and Fundamental Chemistry |
Both gas and liquid flow can be measured in physical quantities of kind volumetric flow rate or mass flow rates, with respective SI units such as cubic meters per second or kilograms per second, respectively. These measurements are related by the material's density. The density of a liquid is almost independent of conditions. This is not the case for gases, the densities of which depend greatly upon pressure, temperature and to a lesser extent, composition.
When gases or liquids are transferred for their energy content, as in the sale of natural gas, the flow rate may also be expressed in terms of energy flow, such as gigajoule per hour or BTU per day. The energy flow rate is the volumetric flow rate multiplied by the energy content per unit volume or mass flow rate multiplied by the energy content per unit mass. Energy flow rate is usually derived from mass or volumetric flow rate by the use of a flow computer.
In engineering contexts, the volumetric flow rate is usually given the symbol , and the mass flow rate, the symbol .
For a fluid having density , mass and volumetric flow rates may be related by . | 1 | Applied and Interdisciplinary Chemistry |
Methods for the polymerization of polyaniline nanofibers seen in literature primarily include [redox|chemical oxidative] polymerization, interfacial synthesis, and "rapid mixing" methods. Other less common methods include nanofiber seeding, electrosynthesis, electrospinning, and preforming polymerization in dilute aniline solutions. | 0 | Theoretical and Fundamental Chemistry |
The first SPR immunoassay was proposed in 1983 by Liedberg, Nylander, and Lundström, then of the Linköping Institute of Technology (Sweden). They adsorbed
human IgG onto a 600-Ångström silver film, and used the assay to detect anti-human IgG in water solution. Unlike many other immunoassays, such as ELISA, an SPR immunoassay is label free in that a label molecule is not required for detection of the analyte. Additionally, the measurements on SPR can be followed real-time allowing the monitoring of individual steps in sequential binding events particularly useful in the assessment of for instance sandwich complexes. | 0 | Theoretical and Fundamental Chemistry |
β-halo immonium compounds can be synthesized through the halogenation reaction of enamines with halides in diethyl ether solvent. Hydrolysis will result in the formation of α-halo ketones. Chlorination, bromination, and even iodination have been shown to be possible. The general reaction is shown below: | 0 | Theoretical and Fundamental Chemistry |
The following processes are often used to describe different stages of a thermodynamic cycle:
*Adiabatic : No energy transfer as heat (Q) during that part of the cycle (). Energy transfer is considered as work done by the system only.
*Isothermal : The process is at a constant temperature during that part of the cycle (T=constant, ). Energy transfer is considered as heat removed from or work done by the system.
*Isobaric : Pressure in that part of the cycle will remain constant. (P=constant, ). Energy transfer is considered as heat removed from or work done by the system.
*Isochoric : The process is constant volume (V=constant, ). Energy transfer is considered as heat removed from the system, as the work done by the system is zero.
*Isentropic : The process is one of constant entropy (S=constant, ). It is adiabatic (no heat nor mass exchange) and reversible.
*Isenthalpic : The process that proceeds without any change in enthalpy or specific enthalpy.
*Polytropic : The process that obeys the relation .
*Reversible : The process where the net entropy production is zero; . | 0 | Theoretical and Fundamental Chemistry |
Transcriptional repressor CTCF also known as 11-zinc finger protein or CCCTC-binding factor is a transcription factor that in humans is encoded by the CTCF gene. CTCF is involved in many cellular processes, including transcriptional regulation, insulator activity, V(D)J recombination and regulation of chromatin architecture. | 1 | Applied and Interdisciplinary Chemistry |
As indicated above, some mammals typically used for food production (such as goats, sheep, pigs, and cows) have been modified to produce non-food products, a practice sometimes called pharming. Use of genetically modified goats has been approved by the FDA and EMA to produce ATryn, i.e. recombinant antithrombin, an anticoagulant protein drug. These products "produced by turning animals into drug-manufacturing machines by genetically modifying them" are sometimes termed biopharmaceuticals.
The patentability of such biopharmaceuticals and their process of manufacture is uncertain. Probably, the biopharmaceuticals themselves so made are unpatentable, assuming that they are chemically identical to the preexisting drugs that they imitate. Several 19th century United States Supreme Court decisions hold that a previously known natural product manufactured by artificial means cannot be patented. An argument can be made for the patentability of the process for manufacturing a biopharmaceutical, however, because genetically modifying animals so that they will produce the drug is dissimilar to previous methods of manufacture; moreover, one Supreme Court decision seems to hold open that possibility.
On the other hand, it has been suggested that the recent Supreme Court decision in Mayo v. Prometheus may create a problem in that, in accordance with the ruling in that case, "it may be said that such and such genes manufacture this protein in the same way they always did in a mammal, they produce the same product, and the genetic modification technology used is conventional, so that the steps of the process 'add nothing to the laws of nature that is not already present. If the argument prevailed in court, the process would also be ineligible for patent protection. This issue has not yet been decided in the courts. | 1 | Applied and Interdisciplinary Chemistry |
With time, various chemical notations for the hydroperoxyl (perhydroxyl) radical coexist in the literature. Haber, Wilstätter and Weiss simply wrote HO or OH, but sometimes HO or OH can also be found to stress the radical character of the species.
The hydroperoxyl radical is a weak acid and gives rise to the superoxide radical (O) when it loses a proton:
:HO → H + O
:sometimes also written as:
:HO → H + O
A first pK value of 4.88 for the dissociation of the hydroperoxyl radical was determined in 1970. The presently accepted value is 4.7. This pK value is close to that of acetic acid. Below a pH of 4.7, the protonated hydroperoxyl radical will dominate in solution while at pH above 4.7 the superoxide radical anion will be the main species. | 1 | Applied and Interdisciplinary Chemistry |
According to the researchers' mass spectrometry, hemolithin is largely composed of glycine and hydroxyglycine amino acids. The researchers noted that the protein was related to "very high extraterrestrial" ratios of Deuterium/Hydrogen (D/H); such high D/H ratios are not found anywhere on Earth, but are "consistent with long-period comets" and suggest, as reported, "that the protein was formed in the proto-solar disc or perhaps even earlier, in interstellar molecular clouds that existed long before the Sun’s birth".
A natural development of hemolithin may have started with glycine forming first, and then later linking with other glycine molecules into polymer chains, and later still, combining with iron and oxygen atoms. The iron and oxygen atoms reside at the end of the newly found molecule. The researchers speculate that the iron oxide grouping formed at the end of the molecule may be able to absorb photons, thereby enabling the molecule to split water (HO) into hydrogen and oxygen and, as a result, produce a source of energy that might be useful to the development of life.
Exobiologist and chemist Jeffrey Bada expressed concerns about the possible protein discovery commenting, "The main problem is the occurrence of hydroxyglycine, which, to my knowledge, has never before been reported in meteorites or in prebiotic experiments. Nor is it found in any proteins. ... Thus, this amino acid is a strange one to find in a meteorite, and I am highly suspicious of the results." Likewise, Lee Cronin of the University of Glasgow stated, "The structure makes no sense." | 0 | Theoretical and Fundamental Chemistry |
* 1993 RACI Polymer Division Citation
* 1999 Applied Research Award and Don Rivett Medal of RACI
* 2002 Euro-Asia Promotion and Cultural Foundation (Romanian Branch)Diploma of Excellence
* 2003 Corresponding Member of the Romanian Academy of Scientists
* 2014 SRB Excellence Award of the Romanian Society for Biomaterials
* 2014 Emeritus Member of Politehnica Foundation, Timișoara, Romania | 0 | Theoretical and Fundamental Chemistry |
In condensed matter physics, a string-net is an extended object whose collective behavior has been proposed as a physical mechanism for topological order by Michael A. Levin and Xiao-Gang Wen. A particular string-net model may involve only closed loops; or networks of oriented, labeled strings obeying branching rules given by some gauge group; or still more general networks. | 0 | Theoretical and Fundamental Chemistry |
When a molecule of DNA is double stranded, as DNA usually is, the two strands run in opposite directions. Therefore, one end of the molecule will have the 3 end of strand 1 and the 5 end of strand 2, and vice versa in the other end. However, the fact that the molecule is two stranded allows numerous different variations. | 1 | Applied and Interdisciplinary Chemistry |
A two-dimensional (2D), solenoidal vector field may be described by a scalar stream function , via , where is the right-handed unit vector perpendicular to the 2D plane. By definition, the stream function is related to the vorticity via a Poisson equation: . The Lamb–Chaplygin model follows from demanding the following characteristics:
* The dipole has a circular atmosphere/separatrix with radius : .
* The dipole propages through an otherwise irrorational fluid ( at translation velocity .
* The flow is steady in the co-moving frame of reference: .
* Inside the atmosphere, there is a linear relation between the vorticity and the stream function
The solution in cylindrical coordinates (), in the co-moving frame of reference reads:
where are the zeroth and first Bessel functions of the first kind, respectively. Further, the value of is such that , the first non-trivial zero of the first Bessel function of the first kind. | 1 | Applied and Interdisciplinary Chemistry |
The deuteron wavefunction must be antisymmetric if the isospin representation is used (since a proton and a neutron are not identical particles, the wavefunction
need not be antisymmetric in general). Apart from their isospin, the two nucleons also have spin and spatial distributions of their wavefunction. The latter is symmetric if the deuteron is symmetric under parity (i.e. have an "even" or "positive" parity), and antisymmetric if the deuteron is antisymmetric under parity (i.e. have an "odd" or "negative" parity). The parity is fully determined by the total orbital angular momentum of the two nucleons: if it is even then the parity is even (positive), and if it is odd then the parity is odd (negative).
The deuteron, being an isospin singlet, is antisymmetric under nucleons exchange due to isospin, and therefore must be symmetric under the double exchange of their spin and location. Therefore, it can be in either of the following two different states:
*Symmetric spin and symmetric under parity. In this case, the exchange of the two nucleons will multiply the deuterium wavefunction by (−1) from isospin exchange, (+1) from spin exchange and (+1) from parity (location exchange), for a total of (−1) as needed for antisymmetry.
*Antisymmetric spin and antisymmetric under parity. In this case, the exchange of the two nucleons will multiply the deuterium wavefunction by (−1) from isospin exchange, (−1) from spin exchange and (−1) from parity (location exchange), again for a total of (−1) as needed for antisymmetry.
In the first case the deuteron is a spin triplet, so that its total spin s is 1. It also has an even parity and therefore even orbital angular momentum l ; The lower its orbital angular momentum, the lower its energy. Therefore, the lowest possible energy state has , .
In the second case the deuteron is a spin singlet, so that its total spin s is 0. It also has an odd parity and therefore odd orbital angular momentum l. Therefore, the lowest possible energy state has , .
Since gives a stronger nuclear attraction, the deuterium ground state is in the , state.
The same considerations lead to the possible states of an isospin triplet having , or , . Thus the state of lowest energy has , , higher than that of the isospin singlet.
The analysis just given is in fact only approximate, both because isospin is not an exact symmetry, and more importantly because the strong nuclear interaction between the two nucleons is related to angular momentum in spin–orbit interaction that mixes different s and l states. That is, s and l are not constant in time (they do not commute with the Hamiltonian), and over time a state such as , may become a state of , . Parity is still constant in time so these do not mix with odd l states (such as , ). Therefore, the quantum state of the deuterium is a superposition (a linear combination) of the , state and the , state, even though the first component is much bigger. Since the total angular momentum j is also a good quantum number (it is a constant in time), both components must have the same j, and therefore . This is the total spin of the deuterium nucleus.
To summarize, the deuterium nucleus is antisymmetric in terms of isospin, and has spin 1 and even (+1) parity. The relative angular momentum of its nucleons l is not well defined, and the deuteron is a superposition of mostly with some . | 0 | Theoretical and Fundamental Chemistry |
Inhibition of DNA repair processes is considered one of main mechanism of inorganic arsenic genotoxicity. Nucleotide excision repair (NER) and base excision repair (BER) are the processes implicated in the repair of DNA base damage induced by ROS after arsenic exposure. In particular, the NER mechanism is the major pathway for repairing bulky distortions in DNA double helix, while the BER mechanism is mainly implicated in the repair of single strand breaks induced by ROS, but inorganic arsenic could also repress the BER mechanism. | 1 | Applied and Interdisciplinary Chemistry |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.