text stringlengths 105 4.57k | label int64 0 1 | label_text stringclasses 2
values |
|---|---|---|
Rotor ships use mast-like cylinders, called Flettner rotors, for propulsion. These are mounted vertically on the ships deck. When the wind blows from the side, the Magnus effect creates a forward thrust. Thus, as with any sailing ship, a rotor ship can only move forwards when there is a wind blowing. The effect is also used in a special type of ship stabilizer consisting of a rotating cylinder mounted beneath the waterline and emerging laterally. By controlling the direction and speed of rotation, strong lift or downforce can be generated. The largest deployment of the system to date is in the motor yacht Eclipse'. | 1 | Applied and Interdisciplinary Chemistry |
He made his debut for Kerry in the 2014 Munster Senior Football Championship semi-final against Clare and scored two points. He lined out in a first Munster Senior Football Championship when they faced Cork, he scored a point in a 0-24 to 0-12 win and a first Munster title. He missed out on Kerry's win over Galway in the All-Ireland quarter-final. He was back in the starting line up for the semi-final with Mayo scoring a point in a 1-16 each draw. An injury while out racing on his quad caused him to miss the 2014 All-Ireland Senior Football Championship semi-final replay win over Mayo. However, he started the 2014 All-Ireland Senior Football Championship Final at right half forward.
Retirements brought new opportunities for OBrien in 2019. He scored Kerrys first goal against Dublin in five games during a 2019 National Football League fixture in Tralee. In the 56th minute of the 2019 All-Ireland Senior Football Championship semi-final against Tyrone, O'Brien scored his fifth championship goal after intercepting a pass from Kieran McGeary, distributing the ball and running the length of the field. | 1 | Applied and Interdisciplinary Chemistry |
Raman spectroelectrochemistry is based on the inelastic scattering or Raman scattering of monochromatic light when strikes on a specific molecule, providing information about vibrational energy of that molecule. Raman spectrum provides highly specific information about the structure and composition of the molecules such as a true fingerprint of them. It has been extensively used to study single wall carbon nanotubes and graphene. | 0 | Theoretical and Fundamental Chemistry |
Metals are predominantly accumulated in the roots causing an unbalanced shoot to root ratio of metal concentrations in most plants. However, in hyperaccumulators, the shoot to root ratio of metal concentrations are abnormally higher in the leaves and much lower in the roots. As this process occurs, metals are efficiently shuttled from the root to the shoot as an enhanced ability in order to protect the roots from metal toxicity.
Delving into tolerance: Throughout the research of hyperaccumulation, there is a conundrum with tolerance. There are several different understandings of tolerance associated with accumulation; however, there are a few similarities. Evidence has conveyed that the traits of tolerance and accumulation are separate to each other and are moderated by genetic and physiological mechanisms. Moreover, the physiological mechanisms, in relation to tolerance, are classified as exclusion: when the movement of metals at the interfaces of soil/root or root/shoot are blocked, or accumulation: when the uptake of metals that have been rendered as non-toxic are allowed into the aerial plant parts.
Characteristics from certain physiological elements:
There are certain characteristics that are specific to certain species. For example, when presented with a low supply of zinc, Thlaspi caerulescens had higher zinc concentrations accumulated compared to other non-accumulator plant species. Further evidence indicated that when T. caerulescens were grown on soil with an adequate amount of contamination, the species accumulated an amount of zinc that was 24-60 times more than Raphanus sativus (radish) had accumulated. Additionally, the capacity to experimentally manipulate soil metal concentrations with soil amendments has allowed researchers to identify the maximum soil concentrations that hyperaccumulation species can tolerate and the minimum soil concentrations in order to reach hyperaccumulation. Furthermore, with these findings, two distinct categories of hyperaccumulation arose, active and passive hyperaccumulation. Active hyperaccumulation is attained by relatively low soil concentrations. Passive hyperaccumulation is induced by exceedingly high soil concentrations. | 1 | Applied and Interdisciplinary Chemistry |
The dipole moment has an important role in orienting proteins to the proper directions and enhancing their abilities to bind to other molecules. The dipole moment of cytochrome c results from a cluster of negatively charged amino acid side chains at the "back" of the enzyme. Despite variations in the number of bound heme groups and variations in sequence, the dipole moment of vertebrate cytochromes c is remarkably conserved. For example, vertebrate cytochromes c all have a dipole moment of approximately 320 debye while cytochromes c of plants and insects have a dipole moment of approximately 340 debye. | 1 | Applied and Interdisciplinary Chemistry |
The Fermi decays () are often referred to as the "superallowed" decays while Gamow–Teller () decays are simple "allowed" decays.
Forbidden decays are those which are substantially more improbable, due to parity violation, and as a result have long decay times.
Now the angular momentum (L) of the systems can be non-zero (in the center-of-mass frame of the system).
Below are the Observed Selection Rules for Nuclear Beta-Decay:
Each of the above have Fermi () and Gamow–Teller () decays.
So for the "first-forbidden" transitions you have
: Fermi
and
: Gamow–Teller
systems.
Notice that (parity violating transition).
The half life of the decay increases with each order: | 0 | Theoretical and Fundamental Chemistry |
Colloidal nanocrystals are a new class of optical materials that essentially constitute a new form of matter that can be considered as "artificial atoms." Like atoms, they have discrete optical energy spectra that are tunable over a wide range of wavelengths. The desired behavior and transmission directly correlates to their size. To change the emitted wavelength, the crystal is grown larger or smaller. Their electronic and optical properties can be controlled by this method. For example, to change the emission from one visible wavelength to another simply use a larger or smaller grown crystal. However, this process would not be effective in conventional semiconductors such as gallium arsenide.
The nanocrystal size controls a widely tunable absorption band resulting in widely tunable emission spectra. This tunability combined with the optical stability of nanocrystals and the great chemical flexibility in the nanocrystal growth have resulted in the widespread nanocrystal applications in use today. Practical device applications range from low-threshold lasers to solar cells and biological imaging and tracking. | 0 | Theoretical and Fundamental Chemistry |
Prior to 1882, the South Island of New Zealand had been experimenting with sowing grass and crossbreeding sheep, which immediately gave their farmers economic potential in the exportation of meat. In 1882, the first successful shipment of sheep carcasses was sent from Port Chalmers in Dunedin, New Zealand, to London. By the 1890s, the frozen meat trade became increasingly more profitable in New Zealand, especially in Canterbury, where 50% of exported sheep carcasses came from in 1900. It was not long before Canterbury meat was known for the highest quality, creating a demand for New Zealand meat around the world. In order to meet this new demand, the farmers improved their feed so sheep could be ready for the slaughter in only seven months. This new method of shipping led to an economic boom in New Zealand by the mid 1890s.
In the United States, the Meat Inspection Act of 1891 was put in place in the United States because local butchers felt the refrigerated railcar system was unwholesome. When meat packing began to take off, consumers became nervous about the quality of the meat for consumption. Upton Sinclairs 1906 novel The Jungle' brought negative attention to the meat packing industry, by drawing to light unsanitary working conditions and processing of diseased animals. The book caught the attention of President Theodore Roosevelt, and the 1906 Meat Inspection Act was put into place as an amendment to the Meat Inspection Act of 1891. This new act focused on the quality of the meat and environment it is processed in. | 0 | Theoretical and Fundamental Chemistry |
A wallpaper remains on the whole unchanged under certain isometries, starting with certain translations that confer on the wallpaper a repetitive nature. One of the reasons to be unchanged under certain translations is that it covers the whole plane. No mathematical object in our minds is stuck onto a motionless wall! On the contrary an observer or his eye is motionless in front of a transformation, which glides or rotates or flips a wallpaper, eventually could distort it, but that would be out of our subject.
If an isometry leaves unchanged a given wallpaper, then the inverse isometry keeps it also unchanged, like translation on image 1, 3 or 4, or a ± 120° rotation around a point like S on image 3 or 4. If they have both this property to leave unchanged a wallpaper, two isometries composed in one or the other order have then this same property to leave unchanged the wallpaper. To be exhaustive about the concepts of group and subgroups under the function composition, represented by the circle shaped symbol ⵔ, here is a traditional truism in mathematics: everything remains itself under the identity transformation. This identity function can be called translation of zero vector or rotation of 360°.
A glide can be represented by one or several arrows if parallel and of same length and same sense, in same way a wallpaper can be represented either by a few patterns or by only one pattern, considered as a pseudo‑tile imagined repeated edge‑to‑edge with an infinite number of replicas. Image 3 shows two patterns with two different contents, and the one in dark dashed lines or one of its images under represents the same wallpaper on the following image 4, by disregarding the colors. Certainly a color is perceived subjectively whereas a wallpaper is an ideal object, however any color can be seen as a label that characterizes certain surfaces, we might think of a hexadecimal code of color as a label specific to certain zones. It may be added that a well‑known theorem deals with colors.
Groups are registered in the catalog by examining properties of a parallelogram, edge‑to‑edge with its replicas. For example its diagonals intersect at their common midpoints, center and symmetry point of any parallelogram, not necessarily symmetry point of its content. Other example, the midpoint of a full side shared by two patterns is the center of a new repetitive parallelogram formed by the two together, center which is not necessarily symmetry point of the content of this double parallelogram. Other possible symmetry point, two patterns symmetric one to the other with respect to their common vertex form together a new repetitive surface, the center of which is not necessarily symmetry point of its content.
Certain rotational symmetries are possible only for certain shapes of pattern. For example on image 2, a Pythagorean tiling is sometimes called pinwheel tilings because of its rotational symmetry of 90 degrees about the center of a tile, either small or large, or about the center of any replica of tile, of course. Also when two equilateral triangles form edge‑to‑edge a rhombic pattern, like on image 4 or 5 (future image 5), a rotational symmetry of 120 degrees about a vertex of a 120° angle, formed by two sides of pattern, is not always a symmetry point of the content of the regular hexagon formed by three patterns together sharing a vertex, because it does not always contain the same motif. | 0 | Theoretical and Fundamental Chemistry |
The biodiesel produced from the processing of microalgae differs from other forms of biodiesel in the content of polyunsaturated fats. Polyunsaturated fats are known for their ability to retain fluidity at lower temperatures. While this may seem like an advantage in production during the colder temperatures of the winter, the polyunsaturated fats result in lower stability during regular seasonal temperatures. | 1 | Applied and Interdisciplinary Chemistry |
Biosynthesis of FeMoco is a complicated process that requires several Nif gene products, specifically those of nifS, nifQ, nifB, nifE, nifN, nifV, nifH, nifD, and nifK (expressed as the proteins NifS, NifU, etc.). FeMoco assembly is proposed to be initiated by NifS and NifU which mobilize Fe and sulfide into small Fe-S fragments. These fragments are transferred to the NifB scaffold and arranged into a FeMoSC cluster before transfer to the NifEN protein (encoded by nifE and nifN) and rearranged before delivery to the MoFe protein. Several other factors participate in the biosynthesis. For example, NifV is the homocitrate synthase that supplies homocitrate to FeMoco. NifV, a protein factor, is proposed to be involved in the storage and/or mobilization of Mo. Fe protein is the electron donor for MoFe protein. These biosynthetic factors have been elucidated and characterized with the exact functions and sequence confirmed by biochemical, spectroscopic, and structural analyses. | 0 | Theoretical and Fundamental Chemistry |
GADV-protein world is a hypothetical stage of abiogenesis. GADV stands for the one letter codes of four amino acids, namely, glycine (G), alanine (A), aspartic acid (D) and valine (V), the main components of GADV proteins. In the GADV-protein world hypothesis, it is argued that the prebiotic chemistry before the emergence of genes involved a stage where GADV-proteins were able to pseudo-replicate. This hypothesis is contrary to the RNA world hypothesis. | 0 | Theoretical and Fundamental Chemistry |
APCI generally suffers less ion suppression than ESI, as discussed previously. Where possible, if ion suppression is unavoidable it may be advisable to switch from ESI to APCI. If this is not possible, it may be useful to switch the ESI ionisation mode from positive to negative. Since fewer compounds are ionisable in negative ionisation mode, it is entirely possible that the ion suppressing species may be removed from the analysis. However, it should also be considered that the analyte of interest may not be ionised effectively in negative mode either, rendering this approach useless. | 0 | Theoretical and Fundamental Chemistry |
Liquid-liquid extractions in the laboratory usually make use of a separatory funnel, where two immiscible phases are combined to separate a solute from one phase into the other, according to the relative solubility in each of the phases. Typically, this will be to extract organic compounds out of an aqueous phase and into an organic phase, but may also include extracting water-soluble impurities from an organic phase into an aqueous phase.
Common extractants may be arranged in increasing order of polarity according to the Hildebrand solubility parameter:
ethyl acetate < acetone < ethanol < methanol < acetone:water (7:3) < ethanol:water (8:2) < methanol:water (8:2) < water
Solid-liquid extractions at laboratory scales can use Soxhlet extractors. A solid sample containing the desired compound along with impurities is placed in the thimble. An extracting solvent is chosen in which the impurities are insoluble and the desired compound has at least limited solubility. The solvent is refluxed and condensed solvent falls into the thimble and dissolves the desired compound which then passes back through the filter into the flask. After extraction is complete the solvent can be removed and the desired product collected. | 0 | Theoretical and Fundamental Chemistry |
(Also see Geometry section above for a discussion of the B-B bonding environment.)
Abstraction of halogens with two equivalents of sodium [[Tetrakis(3,5-bis(trifluoromethyl)phenyl)borate|tetrakis[3,5-bis(trifluoromethyl)phenyl]borate]] gives the dication with both boron atoms within the porphyrin plane. Two reversible reduction waves occur at reduction potentials lower than that of the free base. | 0 | Theoretical and Fundamental Chemistry |
The Mesodinium nuclear code (translation table 29) is a genetic code used by the nuclear genome of the ciliates Mesodinium and Myrionecta. | 1 | Applied and Interdisciplinary Chemistry |
Found in rennet, chymosin is the enzyme responsible for hydrolysis of κ-casein to produce para-κ-casein and glycomacropeptide, which is the first step in formation of cheese, and subsequently curd, and whey. It was the first genetically engineered food additive used commercially. Traditionally, processors obtained chymosin from rennet, a preparation derived from the fourth stomach of milk-fed calves. Scientists engineered a non-pathogenic strain (K-12) of E. coli bacteria for large-scale laboratory production of the enzyme. This microbiologically produced recombinant enzyme, identical structurally to the calf derived enzyme, costs less and is produced in abundant quantities. Today about 60% of U.S. hard cheese is made with genetically engineered chymosin. In 1990, FDA granted chymosin "generally recognized as safe" (GRAS) status based on data showing that the enzyme was safe. | 1 | Applied and Interdisciplinary Chemistry |
The mean free path of a molecule in a gas is the average distance between its collision with other molecules. This is inversely proportional to the pressure of the gas, given constant temperature. In air at STP the mean free path of molecules is about 96 nm. Since electrons are much smaller, their average distance between colliding with molecules is about 5.6 times longer, or about 0.5 μm. This is a substantial fraction of the 7.5 μm spacing between the electrodes for minimal arc voltage. If the electron is in an electric field of 43 MV/m, it will be accelerated and acquire 21.5 eV of energy in 0.5 μm of travel in the direction of the field. The first ionization energy needed to dislodge an electron from nitrogen molecule is about 15.6 eV. The accelerated electron will acquire more than enough energy to ionize a nitrogen molecule. This liberated electron will in turn be accelerated, which will lead to another collision. A chain reaction then leads to avalanche breakdown, and an arc takes place from the cascade of released electrons.
More collisions will take place in the electron path between the electrodes in a higher-pressure gas. When the pressure–gap product is high, an electron will collide with many different gas molecules as it travels from the cathode to the anode. Each of the collisions randomizes the electron direction, so the electron is not always being accelerated by the electric field—sometimes it travels back towards the cathode and is decelerated by the field.
Collisions reduce the electron's energy and make it more difficult for it to ionize a molecule. Energy losses from a greater number of collisions require larger voltages for the electrons to accumulate sufficient energy to ionize many gas molecules, which is required to produce an avalanche breakdown.
On the left side of the Paschen minimum, the product is small. The electron mean free path can become long compared to the gap between the electrodes. In this case, the electrons might gain large amounts of energy, but have fewer ionizing collisions. A greater voltage is therefore required to assure ionization of enough gas molecules to start an avalanche. | 0 | Theoretical and Fundamental Chemistry |
Nested polymerase chain reaction involves two sets of primers, used in two successive runs of polymerase chain reaction, the second set intended to amplify a secondary target within the first run product. This allows amplification for a low number of runs in the first round, limiting non-specific products. The second nested primer set should only amplify the intended product from the first round of amplification and not non-specific product. This allows running more total cycles while minimizing non-specific products. This is useful for rare templates or PCR with high background. | 1 | Applied and Interdisciplinary Chemistry |
SedDB was developed to complement current geological data systems (PetDB, EarthChem, NavDat and Georoc) with an integrated and easily accessible compilation of geochemical data of marine and continental sediments to be utilized for sedimentological, geochemical, petrological, oceanographic, and paleoclimate research, as well as for educational purposes. | 0 | Theoretical and Fundamental Chemistry |
The convection-diffusion equation is a particular example of conservation equation. A conservation equation has the general form:
Where j is the current density term associated to the variable of interest .
In a convection-diffusion equation, the current density of the quantity is the sum of two terms:
* The first, , describes diffusion according to Fick's law. Imagine that is the concentration of a chemical. When concentration is low somewhere compared to the surrounding areas (e.g. a local minimum of concentration), the substance will diffuse in from the surroundings, so the concentration will increase. Conversely, if concentration is high compared to the surroundings (e.g. a local maximum of concentration), then the substance will diffuse out and the concentration will decrease. The net diffusion is proportional to the Laplacian (or second derivative) of concentration if the diffusivity is a constant.
* The second contribution, , describes convection (or advection). For example, in the continuity equation it is present only this term in the current density. Imagine standing on the bank of a river, measuring the waters salinity (amount of salt) each second. Upstream, somebody dumps a bucket of salt into the river. A while later, you would see the salinity suddenly rise, then fall, as the zone of salty water passes by. Thus, the concentration at a given location' can change because of the flow. | 1 | Applied and Interdisciplinary Chemistry |
According to Etymology Online, the verb assay means "to try, endeavor, strive, test the quality of"; from Anglo-French assaier, from assai (noun), from Old French essai, "trial". Thus the noun assay means "trial, test of quality, test of character" (from mid-14th century), from Anglo-French assai; and its meaning "analysis" is from the late 14th century.
For assay of currency coins this literally meant analysis of the purity of the gold or silver (or whatever the precious component) that represented the true value of the coin. This might have translated later (possibly after the 14th century) into a broader usage of "analysis", e.g., in pharmacology, analysis for an important component of a target inside a mixture—such as the active ingredient of a drug inside the inert excipients in a formulation that previously was measured only grossly by its observable action on an organism (e.g., a lethal dose or inhibitory dose). | 1 | Applied and Interdisciplinary Chemistry |
5,6-Dichloro-1-β--ribofuranosylbenzimidazole (DRB) is a chemical compound that inhibits transcription elongation by RNA Polymerase II. Sensitivity to DRB is dependent on DRB sensitivity inducing factor (DSIF), negative elongation factor (NELF), and positive transcription elongation factor b (P-TEFb). DRB is a nucleoside analog and also inhibits some protein kinases. | 1 | Applied and Interdisciplinary Chemistry |
M. Nosonovsky and B. Bhushan studied the effect of unitary (non-hierarchical) structures of micro and nano roughness, and hierarchical structures (micro roughness covered with nano roughness). They found that hierarchical structure was not only necessary for a high contact angle but essential for the stability of the water-solid and water-air interfaces (the composite interface). Due to an external perturbation, a standing capillary wave can form at the liquid–air interface. If the amplitude of the capillary wave is greater than the height of the asperity, the liquid can touch the valley between the asperities; and if the angle under which the liquid comes in contact with the solid is greater than h, it is energetically profitable for the liquid to fill the valley. The effect of capillary waves is more pronounced for small asperities with heights comparable to the wave amplitude. An example of this is seen in the case of unitary roughness, where the amplitude of asperity is very low. This is why the likelihood of instability of a unitary interface will be very high. However, in a recent study, Eyal Bittoun and Abraham Marmur found that multiscale roughness is not necessarily essential for superhydrophobicity but beneficial for mechanical stability of the surface. | 0 | Theoretical and Fundamental Chemistry |
Pyrimidine nucleosides include cytidine, uridine, and thymidine. The synthesis of any pyrimidine nucleotide begins with the formation of uridine. This reaction requires aspartate, glutamine, bicarbonate, and 2 ATP molecules (to provide energy), as well as PRPP which provides ribose-monophosphate. Unlike in purine synthesis, the sugar/phosphate group from PRPP is not added to the nitrogenous base until towards the end of the process. After synthesizing uridine-monophosphate, it can react with 2 ATP to form uridine-triphosphate or UTP. UTP can be converted to CTP (cytidine-triphosphate) in a reaction catalyzed by CTP synthetase. Thymidine synthesis first requires reduction of the uridine to deoxyuridine (see next section), before the base can be methylated to produce thymidine.
ATP, a purine nucleotide, is an activator of pyrimidine synthesis, while CTP, a pyrimidine nucleotide, is an inhibitor of pyrimidine synthesis. This regulation helps to keep the purine/pyrimidine amounts similar, which is beneficial because equal amounts of purines and pyrimidines are required for DNA synthesis.
Deficiencies of enzymes involved in pyrimidine synthesis can lead to the genetic disease Orotic aciduria which causes excessive excretion of orotic acid in the urine. | 1 | Applied and Interdisciplinary Chemistry |
A single, consensus definition of a soliton is difficult to find. ascribe three properties to solitons:
# They are of permanent form;
# They are localized within a region;
# They can interact with other solitons, and emerge from the collision unchanged, except for a phase shift.
More formal definitions exist, but they require substantial mathematics. Moreover, some scientists use the term soliton for phenomena that do not quite have these three properties (for instance, the light bullets of nonlinear optics are often called solitons despite losing energy during interaction). | 1 | Applied and Interdisciplinary Chemistry |
With certain polar substituents, hydrogen bonding can occur in the allylic system between the substituents. Rather than the strain that would normally occur in the close group proximity, the hydrogen bond stabilizes the conformation and makes it energetically much more favorable. This scenario occurs when the allylic substituent at the 1 position is a hydrogen bond donor (usually a hydroxyl) and the substituent at the 3 position is a hydrogen bond acceptor (usually an ether). Even in cases where the allylic system could conform to put a much smaller hydrogen in the hydrogen bond acceptor’s position, it is much more favorable to allow the hydrogen bond to form. | 0 | Theoretical and Fundamental Chemistry |
The Strep-tag system offers a selective tool to purify proteins under physiological conditions. The proteins obtained are bioactive and display a very high purity (above 95%). Also, the Strep-tag system can be used for protein detection in various assays. Depending on the experimental circumstances, Strep-tag antibodies or Strep-Tactin, with an enzymatic (e.g.horseradish peroxidase (HRP), alkaline phosphatase (AP)) or fluorescence (e.g. green fluorescent protein (GFP)) marker. If high purity is required, the lysate can be purified by first using Strep-Tactin and then perform a second run using antibodies against Strep-tag. This reduces the contamination with unspecific bound proteins, which might occur in some rare scenarios.
Following assays can be conducted using the Strep-tag detection system:
* one-step affinity purification
* Protein:protein interaction studies
* Colony blot, dot blot, Western blot and ELISA
* Screening for positive expression clones
* Immunocytochemistry and Immunohistochemistry
* Protein localization and targeting studies
Because the Strep-tag is capable of isolating protein complexes, strategies for the study of protein-protein interactions can also be conducted. Another option is the immobilization of Strep-tag proteins with a specific high affinity antibody on microplates or biochips.
Strep-Tag/StrepTactin system is also used in single-molecule optical tweezers and atomic force microscope experiments, showing high mechanical stability comparable to the strongest non-covalent linkages currently available. | 1 | Applied and Interdisciplinary Chemistry |
*Gilmore G, Hemingway J. Practical Gamma-Ray Spectrometry. John Wiley & Sons, Chichester: 1995, .
*Knoll G, Radiation Detection and Measurement. John Wiley & Sons, Inc. NY:2000, .
*Nucleonica Wiki. [https://web.archive.org/web/20120226211611/http://www.nucleonica.net/wiki/index.php/Help:Gamma_Spectrum_Generator Gamma Spectrum Generator]. Accessed 8 October 2008. | 0 | Theoretical and Fundamental Chemistry |
LEXO is the original version of the upgraded BURNOUT temperature regulating tumbler brand from manufacturer ThermAvant International, LLC, based in Columbia, Missouri. | 0 | Theoretical and Fundamental Chemistry |
The prostaglandin E (PGE) receptors are G protein-coupled receptors that bind and are activated by prostaglandin E. They are members of the prostaglandin receptors class of receptors and include the following Protein isoforms:
* Prostaglandin E receptor 1 (EP) -
* Prostaglandin E receptor 2 (EP) -
* Prostaglandin E receptor 3 (EP) -
* Prostaglandin E receptor 4 (EP) - | 1 | Applied and Interdisciplinary Chemistry |
He was born in East Dereham in Norfolk, the son of the Francis Wollaston (1737–1815), a noted amateur astronomer, and his wife Althea Hyde. He was one of 17 children, but the family was financially well-off and he enjoyed an intellectually stimulating environment. He was educated privately (and remotely) at Charterhouse School from 1774 to 1778 then studied Sciences at Gonville and Caius College, Cambridge. In 1793 he obtained his doctorate (MD) in medicine from Cambridge University, and was a Fellow of his college from 1787 to 1828.
He worked as a physician in Huntingdon from 1789 then moved to Bury St Edmunds before moving to London in 1797. During his studies, Wollaston had become interested in chemistry, crystallography, metallurgy and physics. In 1800, after he had received a large sum of money from one of his older brothers, he left medicine. He concentrated on pursuing his interests in chemistry and other subjects outside his trained vocation.
He was elected a Fellow of the Royal Society in 1793, where he became an influential member. He served as its president in 1820. In 1822 he was elected a Foreign Honorary Member of the American Academy of Arts and Sciences.
Wollaston died in London 28 December 1828 and was buried in St Nicholas's Churchyard in Chislehurst, England. | 1 | Applied and Interdisciplinary Chemistry |
In 1860, Edward Frankland was the first to report the preparation and isolation of a boronic acid. Ethylboronic acid was synthesized by a two-stage process. First, diethylzinc and triethyl borate reacted to produce triethylborane. This compound then oxidized in air to form ethylboronic acid. Several synthetic routes are now in common use, and many air-stable boronic acids are commercially available.
Boronic acids typically have high melting points. They are prone to forming anhydrides by loss of water molecules, typically to give cyclic trimers. | 0 | Theoretical and Fundamental Chemistry |
In intramolecular organic reactions, two reaction sites are contained within a single molecule. This configuration elevates the effective concentration of the reacting partners resulting in high reaction rates. Many intramolecular reactions are observed where the intermolecular version does not take place.
Intramolecular reactions, especially ones leading to the formation of 5- and 6-membered rings, are rapid compared to an analogous intermolecular process. This is largely a consequence of the reduced entropic cost for reaching the transition state of ring formation and the absence of significant strain associated with formation of rings of these sizes. For the formation of different ring sizes via cyclization of substrates of varying tether length, the order of reaction rates (rate constants k for the formation of an n-membered ring) is usually k > k > k > k > k as shown below for a series of ω-bromoalkylamines. This somewhat complicated rate trend reflects the interplay of these entropic and strain factors:
For the <nowiki/>small rings<nowiki/> (3- and 4- membered), the slow rates is a consequence of angle strain experienced at the transition state. Although three-membered rings are more strained, formation of aziridine is faster than formation of azetidine due to the proximity of the leaving group and nucleophile in the former, which increases the probability that they would meet in a reactive conformation. The same reasoning holds for the <nowiki/>unstrained rings<nowiki/> (5-, 6-, and 7-membered). The formation of <nowiki/>medium-sized rings<nowiki/> (8- to 13-membered) is particularly disfavorable due to a combination of an increasingly unfavorable entropic cost and the additional presence of transannular strain arising from steric interactions across the ring. Finally, for <nowiki/>large rings (14-membered or higher), the rate constants level off, as the distance between the leaving group and nucleophile is now so large the reaction is now effectively intermolecular.
Although the details may change somewhat, the general trends hold for a variety of intramolecular reactions, including radical-mediated and (in some cases) transition metal-catalyzed processes. | 0 | Theoretical and Fundamental Chemistry |
The jiggle pump consists of a chamber, in line with the end of the pipe that sits in the liquid to be moved. The chamber is somewhat wider than the pipe, and narrows to approximately the pipe diameter at both ends. One end attaches to the pipe, the other end is open to the liquid. Within the chamber is a sphere, denser than the liquid to be pumped, small enough to move freely within the chamber but large enough to not be able to leave the chamber.
To begin with, gravity holds the sphere at the bottom, open, end of the chamber, although hydrostatic pressure will force the liquid up and around the sphere upon immersion. When the pipe is vigorously shaken up and down, the sphere moves upwards, lifting some liquid in the pipe; then when it falls down again, the increased hydrostatic pressure within the pipe (which now has a higher head of fluid in it than the surrounding container) pushes the sphere down and prevents the liquid flowing back. Repeated "jigglings" lift the fluid up the pipe until it reaches the highest point in the pipe, whereupon gravity causes it to start to flow down the other side, and the syphon action will "suck" the liquid through the system. This causes the pressure in the pipe to drop below the hydrostatic pressure in the container, so the sphere is lifted upwards, allowing the liquid to flow. | 1 | Applied and Interdisciplinary Chemistry |
Cavendishs electrical and chemical experiments, like those on heat, had begun while he lived with his father in a laboratory in their London house. Lord Charles Cavendish died in 1783, leaving almost all of his very substantial estate to Henry. Like his theory of heat, Cavendishs comprehensive theory of electricity was mathematical in form and was based on precise quantitative experiments. Working with his colleague, Timothy Lane, he created an artificial torpedo fish that could dispense electric shocks to show that the source of shock from these fish was electricity. He published an early version of his theory of electricity in 1771, based on an expansive electrical fluid that exerted pressure. He demonstrated that if the intensity of electric force were inversely proportional to distance, then the electric fluid more than that needed for electrical neutrality would lie on the outer surface of an electrified sphere; then he confirmed this experimentally. Cavendish continued to work on electricity after this initial paper, but he published no more on the subject.
Cavendish wrote papers on electrical topics for the Royal Society but the bulk of his electrical experiments did not become known until they were collected and published by James Clerk Maxwell a century later, in 1879, long after other scientists had been credited with the same results. Cavendishs electrical papers from the Philosophical Transactions of the Royal Society of London have been reprinted, together with most of his electrical manuscripts, in The Scientific Papers of the Honourable Henry Cavendish, F.R.S. (1921). According to the 1911 edition of Encyclopædia Britannica, among Cavendishs discoveries were the concept of electric potential (which he called the "degree of electrification"), an early unit of capacitance (that of a sphere one inch in diameter), the formula for the capacitance of a plate capacitor, the concept of the dielectric constant of a material, the relationship between electric potential and current (now called Ohms law) (1781), laws for the division of current in parallel circuits (now attributed to Charles Wheatstone), and the inverse square law of variation of electric force with distance, now called Coulombs law. | 1 | Applied and Interdisciplinary Chemistry |
This pattern follows from the dispersion relation of deep water waves, which is often written as,
where
: = the strength of the gravity field
: is the angular frequency in radians per second
: = angular wavenumber in radians per metre
"Deep" means that the depth is greater than half of the wavelength.
This formula implies that the group velocity of a deep water wave is half of its phase velocity, which, in turn, goes as the square root of the wavelength.
Two velocity parameters of importance for the wake pattern are:
: is the relative velocity of the water and the surface object that causes the wake.
: is the phase velocity of a wave, varying with wave frequency. | 1 | Applied and Interdisciplinary Chemistry |
The genomic distribution of SNPs is not homogenous; SNPs occur in non-coding regions more frequently than in coding regions or, in general, where natural selection is acting and "fixing" the allele (eliminating other variants) of the SNP that constitutes the most favorable genetic adaptation. Other factors, like genetic recombination and mutation rate, can also determine SNP density.
SNP density can be predicted by the presence of microsatellites: AT microsatellites in particular are potent predictors of SNP density, with long (AT)(n) repeat tracts tending to be found in regions of significantly reduced SNP density and low GC content. | 1 | Applied and Interdisciplinary Chemistry |
An E1 reaction consists of a unimolecular elimination, where the rate determining step of the mechanism depends on the removal of a single molecular species. This is a two-step mechanism. The more stable the carbocation intermediate is, the faster the reaction will proceed, favoring the products. Stabilization of the carbocation intermediate lowers the activation energy. The reactivity order is (CH3)3C- > (CH3)2CH- > CH3CH2- > CH3-.
Furthermore, studies describe a typical kinetic resolution process that starts out with two enantiomers that are energetically equivalent and, in the end, forms two energy-inequivalent intermediates, referred to as diastereomers. According to Hammond's postulate, the more stable diastereomer is formed faster. | 0 | Theoretical and Fundamental Chemistry |
Green derived his shoaling law for water waves by use of what is now known as the Liouville–Green method, applicable to gradual variations in depth and width along the path of wave propagation. | 1 | Applied and Interdisciplinary Chemistry |
1,8-Bis(dimethylamino)naphthalene is an organic compound with the formula CH(NMe) (Me = methyl). It is classified as a peri-naphthalene, i.e. a 1,8-disubstituted derivative of naphthalene. Owing to its unusual structure, it exhibits exceptional basicity. It is often referred by the trade name Proton Sponge, a trademark of Sigma-Aldrich. | 0 | Theoretical and Fundamental Chemistry |
The antiviral drug ritonavir exists as two polymorphs, which differ greatly in efficacy. Such issues were solved by reformulating the medicine into gelcaps and tablets, rather than the original capsules. | 0 | Theoretical and Fundamental Chemistry |
The Society awards the AAG Gold Medal to recognize a lifetime's achievement in or outstanding contribution to applied geochemistry. It also offers an annual student paper prize to reward student contributors of outstanding papers on geochemistry. | 0 | Theoretical and Fundamental Chemistry |
From the Greek αγωνιστής (agōnistēs), contestant; champion; rival < αγων (agōn), contest, combat; exertion, struggle < αγω (agō), I lead, lead towards, conduct; drive | 1 | Applied and Interdisciplinary Chemistry |
In particular to building materials, moisture sorption has significant implications for cements, woods, insulation materials, and fibers. Moisture damage is a significant factor limiting a buildings lifespan. As well, moisture infusion through a buildings outer structure can have a significant effect on indoor air quality and air-conditioning load. | 0 | Theoretical and Fundamental Chemistry |
A volumetric pipette, bulb pipette, or belly pipette allows extremely accurate measurement (to four significant figures) of the volume of a solution. It is calibrated to deliver accurately a fixed volume of liquid.
These pipettes have a large bulb with a long narrow portion above with a single graduation mark as it is calibrated for a single volume (like a volumetric flask). Typical volumes are 1, 2, 5, 10, 20, 25, 50 and 100 mL. Volumetric pipettes are commonly used in analytical chemistry to make laboratory solutions from a base stock as well as to prepare solutions for titration.
ASTM standard E969 defines the standard tolerance for volumetric transfer pipettes. The tolerance depends on the size: a 0.5-mL pipette has a tolerance of ±0.006 mL, while a 50-mL pipette has a tolerance of ±0.05 mL. (These are for Class A pipettes; Class B pipettes are given a tolerance of twice that for the corresponding Class A.)
A specialized example of a volumetric pipette is the microfluid pipette (capable of dispensing as little as 10 µL) designed with a circulating liquid tip that generates a self-confining volume in front of its outlet channels. | 0 | Theoretical and Fundamental Chemistry |
Carbon Catabolite Repression—Negative On TATA-less, or CCR4-Not, is a multiprotein complex that functions in gene expression. The complex has multiple enzymatic activities as both a poly(A) 3′-5′ exonuclease and a ubiquitin ligase. The exonuclease activity of CCR4-Not shortens the poly(A) tail found at 3' end of almost every eukaryotic mRNA. The complex is present both in the nucleus where it regulates transcription and in the cytoplasm where it associates with translating ribosomes and RNA processing bodies. In mammalian cell, it has a function in the regulation of the cell cycle, chromatin modification, activation and inhibition of transcription initiation, control of transcription elongation, RNA export, nuclear RNA surveillance, and DNA damage repair in nucleus. Ccr4–Not complex plays an important role in mRNA decay and protein quality control in the cytoplasm. | 1 | Applied and Interdisciplinary Chemistry |
Ribosomally synthesized and post-translationally modified peptides (RiPPs), also known as ribosomal natural products, are a diverse class of natural products of ribosomal origin. Consisting of more than 20 sub-classes, RiPPs are produced by a variety of organisms, including prokaryotes, eukaryotes, and archaea, and they possess a wide range of biological functions.
As a consequence of the falling cost of genome sequencing and the accompanying rise in available genomic data, scientific interest in RiPPs has increased in the last few decades. Because the chemical structures of RiPPs are more closely predictable from genomic data than are other natural products (e.g. alkaloids, terpenoids), their presence in sequenced organisms can, in theory, be identified rapidly. This makes RiPPs an attractive target of modern natural product discovery efforts. | 1 | Applied and Interdisciplinary Chemistry |
The vapor-compression cycle is used in most household refrigerators as well as in many large commercial and industrial refrigeration systems. Figure 1 provides a schematic diagram of the components of a typical vapor-compression refrigeration system.
The thermodynamics of the cycle can be analyzed on a diagram as shown in Figure 2. In this cycle, a circulating refrigerant such as a low boiling hydrocarbon or hydrofluorocarbons enters the compressor as a vapour. From point 1 to point 2, the vapor is compressed at constant entropy and exits the compressor as a vapor at a higher temperature, but still below the vapor pressure at that temperature. From point 2 to point 3 and on to point 4, the vapor travels through the condenser which cools the vapour until it starts condensing, and then condenses the vapor into a liquid by removing additional heat at constant pressure and temperature. Between points 4 and 5, the liquid refrigerant goes through the expansion valve (also called a throttle valve) where its pressure abruptly decreases, causing flash evaporation and auto-refrigeration of, typically, less than half of the liquid.
That results in a mixture of liquid and vapour at a lower temperature and pressure as shown at point 5. The cold liquid-vapor mixture then travels through the evaporator coil or tubes and is completely vaporized by cooling the warm air (from the space being refrigerated) being blown by a fan across the evaporator coil or tubes. The resulting refrigerant vapour returns to the compressor inlet at point 1 to complete the thermodynamic cycle.
The above discussion is based on the ideal vapour-compression refrigeration cycle, and does not take into account real-world effects like frictional pressure drop in the system, slight thermodynamic irreversibility during the compression of the refrigerant vapor, or non-ideal gas behavior, if any. Vapor compression refrigerators can be arranged in two stages in cascade refrigeration systems, with the second stage cooling the condenser of the first stage. This can be used for achieving very low temperatures.
More information about the design and performance of vapor-compression refrigeration systems is available in the classic Perrys Chemical Engineers Handbook. | 0 | Theoretical and Fundamental Chemistry |
Pipe expansion joints are necessary in systems that convey high temperature substances such as steam or exhaust gases, or to absorb movement and vibration. A typical joint is a bellows of metal (most commonly stainless steel), plastic (such as PTFE), fabric (such as glass fibre) or an elastomer such as rubber.
A bellows is made up of a series of convolutions, with the shape of the convolution designed to withstand the internal pressures of the pipe, but flexible enough to accept axial, lateral, and angular deflections. Expansion joints are also designed for other criteria, such as noise absorption, anti-vibration, earthquake movement, and building settlement. Metal expansion joints have to be designed according to rules laid out by EJMA, for fabric expansion joints there are guidelines and a state-of-the-art description by the Quality Association for Fabric Expansion Joints. Pipe expansion joints are also known as "compensators", as they compensate for the thermal movement. | 1 | Applied and Interdisciplinary Chemistry |
Rhamnolipids have long been reported to have antimicrobial properties. They have been shown to have activity against a range of bacteria including Serratia marcescens, Klebsiella pneumoniae, Staphylococcus aureus and Bacillus subtilis with minimum inhibitory concentrations (MICs) ranging from 0.5 µg/mL to 32 µg/mL. Activity against several fungi such as Fusarium solani and Penicillium funiculosum have also been observed with MICs of 75 µg/mL and 16 µg/mL respectively. Rhamnolipids have been suggested as antimicrobials able to remove Bordetella bronchiseptica biofilms. The mode of killing has been shown to result from intercalation of rhamnolipids into the cell membrane causing pores to form which result in cell lysis, at least in the case of Bacillus subtilis. The anti-microbial action of rhamnolipids may provide a fitness advantage for Pseudomonas aeruginosa by excluding other microorganisms from the colonised niche. Furthermore, rhamnolipids have been shown to have anti-viral and zoosporicidal activities. The antimicrobial properties of rhamnolipids may confer a fitness advantage for Pseudomonas aeruginosa in niche colonisation as Pseudomonas aeruginosa is a soil bacterium, as well as competing with other bacteria in the cystic fibrosis lung. | 0 | Theoretical and Fundamental Chemistry |
ADP cycling supplies the energy needed to do work in a biological system, the thermodynamic process of transferring energy from one source to another. There are two types of energy: potential energy and kinetic energy. Potential energy can be thought of as stored energy, or usable energy that is available to do work. Kinetic energy is the energy of an object as a result of its motion. The significance of ATP is in its ability to store potential energy within the phosphate bonds. The energy stored between these bonds can then be transferred to do work. For example, the transfer of energy from ATP to the protein myosin causes a conformational change when connecting to actin during muscle contraction.
It takes multiple reactions between myosin and actin to effectively produce one muscle contraction, and, therefore, the availability of large amounts of ATP is required to produce each muscle contraction. For this reason, biological processes have evolved to produce efficient ways to replenish the potential energy of ATP from ADP.
Breaking one of ATP's phosphorus bonds generates approximately 30.5 kilojoules per mole of ATP (7.3 kcal). ADP can be converted, or powered back to ATP through the process of releasing the chemical energy available in food; in humans, this is constantly performed via aerobic respiration in the mitochondria. Plants use photosynthetic pathways to convert and store energy from sunlight, also conversion of ADP to ATP. Animals use the energy released in the breakdown of glucose and other molecules to convert ADP to ATP, which can then be used to fuel necessary growth and cell maintenance. | 1 | Applied and Interdisciplinary Chemistry |
In cell culture, a monolayer refers to a layer of cells in which no cell is growing on top of another, but all are growing side by side and often touching each other on the same growth surface. | 0 | Theoretical and Fundamental Chemistry |
Receptors are proteins that bind small ligands. The dissociation constant K is used as indicator of the affinity of the ligand to the receptor. The higher the affinity of the ligand for the receptor the lower the K value (and the higher the pK value). | 0 | Theoretical and Fundamental Chemistry |
Building on the reactivity of the triphenylphosphine ligand, the structure of ligands used for the Tsuji–Trost reaction quickly became more complex. Today, these ligands may contain phosphorus, sulfur, nitrogen or some combination of these elements, but most studies have concentrated on the mono- and diphosphine ligands. These ligands can be further classified based on the nature of their chirality, with some ligands containing central chirality on the phosphorus or carbon atoms, some containing biaryl axial chirality, and others containing planar chirality.
Diphosphine ligands with central chirality emerged as an effective type of ligand (particularly for asymmetric allylic alkylation procedures) with the Trost Ligand being one such example.
Phosphinooxazolines (PHOX) ligands have been employed in the AAA, particularly with carbon-based nucleophiles. | 0 | Theoretical and Fundamental Chemistry |
Phosphonium iodide is prepared by mixing diphosphorus tetraiodide () with elemental phosphorus and water at 80 °C and allowing the salt to sublime. | 0 | Theoretical and Fundamental Chemistry |
The most widely used numerical laser diffraction results are:
* The median volume-weighted diameter, or D. Derived from the cumulative curve, it represents the particle diameter separating the upper 50 % of the data from the lower 50 %.
* The D and D values, also derived from the cumulative curve.
* The mean volume-weighted diameter, also termed D[4,3] or De Brouckere mean diameter.
* The span, which gives a measure of the width of the particle size distribution, and is calculated as span = [D – D]/D. | 0 | Theoretical and Fundamental Chemistry |
*450 masters-level engineering students
*200 internships in France and abroad
*100 professors, assistant professors and CNRS researchers (permanent staff)
*180 graduate students | 1 | Applied and Interdisciplinary Chemistry |
The layer in which the shearing viscous forces are significant, is called the boundary layer. This boundary layer is a hypothetical concept. It divides the flow in pipe into two regions:
# Boundary layer region: The region in which viscous effects and the velocity changes are significant.
# The irrotational (core) flow region: The region in which viscous effects and velocity changes are negligible, also known as the inviscid core.
When the fluid just enters the pipe, the thickness of the boundary layer gradually increases from zero moving in the direction of fluid flow and eventually reaches the pipe center and fills the entire pipe. This region from the entrance of the pipe to the point where the boundary layer covers the entire pipe is termed as the hydrodynamic entrance region and the length of the pipe in this region is termed as the hydrodynamic entry length. In this region, the velocity profile develops and thus the flow is called the hydrodynamically developing flow. After this region, the velocity profile is fully developed and continues unchanged. This region is called the hydrodynamically fully developed region. But this is not the fully developed fluid flow until the normalized temperature profile also becomes constant.
In case of laminar flow, the velocity profile in the fully developed region is parabolic but in the case of turbulent flow it gets a little flatter due to vigorous mixing in radial direction and eddy motion.
The velocity profile remains unchanged in the fully developed region.
Hydrodynamic Fully Developed velocity profile Laminar Flow :
where is in the flow direction. | 1 | Applied and Interdisciplinary Chemistry |
The use of P,N ligands in asymmetric hydrogenation can be traced to the C symmetric bisoxazoline ligand. However, these symmetric ligands were soon superseded by monooxazoline ligands whose lack of C symmetry has in no way limits their efficacy in asymmetric catalysis. Such ligands generally consist of an achiral nitrogen-containing heterocycle that is functionalized with a pendant phosphorus-containing arm, although both the exact nature of the heterocycle and the chemical environment phosphorus center has varied widely. No single structure has emerged as consistently effective with a broad range of substrates, although certain privileged structures (like the phosphine-oxazoline or PHOX architecture) have been established. Moreover, within a narrowly defined substrate class the performance of metallic complexes with chiral P,N ligands can closely approach perfect conversion and selectivity in systems otherwise very difficult to target. Certain complexes derived from chelating P-O ligands have shown promising results in the hydrogenation of α,β-unsaturated ketones and esters. | 0 | Theoretical and Fundamental Chemistry |
Five common thermodynamic potentials are:
where = temperature, = entropy, = pressure, = volume. is the number of particles of type in the system and is the chemical potential for an -type particle. The set of all are also included as natural variables but may be ignored when no chemical reactions are occurring which cause them to change. The Helmholtz free energy is in ISO/IEC standard called Helmholtz energy or Helmholtz function. It is often denoted by the symbol , but the use of is preferred by IUPAC, ISO and IEC.
These five common potentials are all potential energies, but there are also entropy potentials. The thermodynamic square can be used as a tool to recall and derive some of the potentials.
Just as in mechanics, where potential energy is defined as capacity to do work, similarly different potentials have different meanings like the below:
* Internal energy () is the capacity to do work plus the capacity to release heat.
* Gibbs energy () is the capacity to do non-mechanical work.
* Enthalpy () is the capacity to do non-mechanical work plus the capacity to release heat.
* Helmholtz energy () is the capacity to do mechanical work plus non-mechanical work.
From these meanings (which actually apply in specific conditions, e.g. constant pressure, temperature, etc.), for positive changes (e.g., ), we can say that is the energy added to the system, is the total work done on it, is the non-mechanical work done on it, and is the sum of non-mechanical work done on the system and the heat given to it.
Note that the sum of internal energy is conserved, but the sum of Gibbs energy, or Helmholtz energy, are not conserved, despite being named "energy". They can be better interpreted as the potential to perform "useful work", and the potential can be wasted.
Thermodynamic potentials are very useful when calculating the equilibrium results of a chemical reaction, or when measuring the properties of materials in a chemical reaction. The chemical reactions usually take place under some constraints such as constant pressure and temperature, or constant entropy and volume, and when this is true, there is a corresponding thermodynamic potential that comes into play. Just as in mechanics, the system will tend towards a lower value of a potential and at equilibrium, under these constraints, the potential will take the unchanging minimum value. The thermodynamic potentials can also be used to estimate the total amount of energy available from a thermodynamic system under the appropriate constraint.
In particular: (see principle of minimum energy for a derivation)
* When the entropy and "external parameters" (e.g. volume) of a closed system are held constant, the internal energy decreases and reaches a minimum value at equilibrium. This follows from the first and second laws of thermodynamics and is called the principle of minimum energy. The following three statements are directly derivable from this principle.
* When the temperature and external parameters of a closed system are held constant, the Helmholtz free energy decreases and reaches a minimum value at equilibrium.
* When the pressure and external parameters of a closed system are held constant, the enthalpy decreases and reaches a minimum value at equilibrium.
* When the temperature , pressure and external parameters of a closed system are held constant, the Gibbs free energy decreases and reaches a minimum value at equilibrium. | 0 | Theoretical and Fundamental Chemistry |
Aquatic biomonitoring is an important tool for assessing aquatic life forms and their habitats. It can reveal the overall health and status of the ecosystem, detect environmental trends and the impacts of different stressors, and can be used to evaluate the effect that various human activities have on the overall health of aquatic environments. Water pollution and general stresses to aquatic life have a major impact on the environment. The main sources of pollution to oceans, rivers, and lakes are human caused events or activities, such as sewage, oil spills, surface runoff, littering, ocean mining, and nuclear waste.
Monitoring aquatic life can also be beneficial in monitoring and understanding adjacent land ecosystems. Rapid changes to an environment, like, pollution, can alter ecosystems and community assemblages, and endanger species that live in or close to water. Many aquatic species serve as food sources for terrestrial species, which are therefore impacted by the size and health of aquatic populations. | 1 | Applied and Interdisciplinary Chemistry |
Axe-monies (Spanish: Tajaderos) refer to bronze artifacts found in both western Mesoamerica and the northern Andes. Based on ethnohistorical, archaeological, chemical, and metallurgical analyses, the scholars Hosler, Lechtman and Holm have argued for their use in both regions (which are separated by thousands of miles) through trade. In contrast to naipes, bow-tie- or card-shaped metal objects which appear in the archaeological record only in the northern Andean coastal region, axe-monies are found in both Mesoamerican and Andean cultural zones. More specifically, it is argued that the system of money first arose on the north coast of Peru and Ecuador in the early second millennium CE. In both regions, bronze was smelted, likely by family units, and hammered into thin, axe-shaped forms and bundled in multiples of five, usually twenty. As they are often found in burials, it is likely that in addition to their presumed economic use, they also had ceremonial value. | 1 | Applied and Interdisciplinary Chemistry |
Many experiments are continuing in the production of metallic hydrogen in laboratory conditions at static compression and low temperature. Arthur Ruoff and Chandrabhas Narayana from Cornell University in 1998, and later Paul Loubeyre and René LeToullec from Commissariat à l'Énergie Atomique, France in 2002, have shown that at pressures close to those at the center of the Earth () and temperatures of , hydrogen is still not a true alkali metal, because of the non-zero band gap. The quest to see metallic hydrogen in laboratory at low temperature and static compression continues. Studies are also ongoing on deuterium. Shahriar Badiei and Leif Holmlid from the University of Gothenburg have shown in 2004 that condensed metallic states made of excited hydrogen atoms (Rydberg matter) are effective promoters to metallic hydrogen, however these results are disputed. | 0 | Theoretical and Fundamental Chemistry |
Variations of the steroid 21-hydroxylase can be found in all vertebrates.
Cyp21 first emerged in chordates before the speciation between basal chordates and vertebrates. The sea lamprey, an early jawless fish species that originated over 500 million years ago, provides valuable insights into the evolution and emergence of Cyp21. Sea lampreys lack the 11β-hydroxylase enzyme responsible for converting 11-deoxycortisol to cortisol as observed in mammals. Instead, they rely on 11-deoxycortisol, a product of a reaction catalyzed by CYP21, as their primary glucocorticoid hormone with mineralocorticoid properties. This suggests the presence of a complex and highly specific corticosteroid signaling pathway that emerged at least half a billion years ago during early vertebrate evolution.
In vertebrates, such as fish, amphibians, reptiles, birds, and mammals, Cyp21 participates in the biosynthesis of glucocorticoids and mineralocorticoids, therefore, Cyp21 is essential for the regulation of stress response, electrolyte balance and blood pressure, immune system, and metabolism in vertebrates.
Cyp21 is relatively conserved among mammals, and shows some variations in its structure, expression, and regulation. Rhesus macaques and orangutans possess two copies of Cyp21, while chimpanzees have three, still, a pseudogene (CYP21A1P) is only present in humans among primates. | 1 | Applied and Interdisciplinary Chemistry |
Veterans are presented with awards and are thanked for their service on formalities such as ceremonies which are plentiful and widely covered in the Iranian media, particularly on two annual national occasions, namely Disabled Veterans' Day in May and Sacred Defence Week (Sept. 20–27), which commemorates the commencement of the Iran–Iraq War.
According to the supreme leader of Iran, Ali Khamenei, "disabled war veterans are images of the war crimes of big powers who encouraged former Iraqi dictator Saddam Hussein to invade Iran." | 1 | Applied and Interdisciplinary Chemistry |
Potassium is the only optically pumped magnetometer that operates on a single, narrow electron spin resonance (ESR) line in contrast to other alkali vapour magnetometers that use irregular, composite and wide spectral lines and helium with the inherently wide spectral line. | 0 | Theoretical and Fundamental Chemistry |
The behavior of quantum dots (QDs) in solution and their interaction with other surfaces is of great importance to biological and industrial applications, such as optical displays, animal tagging, anti-counterfeiting dyes and paints, chemical sensing, and fluorescent tagging. However, unmodified quantum dots tend to be hydrophobic, which precludes their use in stable, water-based colloids. Furthermore, because the ratio of surface area to volume in a quantum dot is much higher than for larger particles, the thermodynamic free energy associated with dangling bonds on the surface is sufficient to impede the quantum confinement of excitons. Once solubilized by encapsulation in either a hydrophobic interior micelle or a hydrophilic exterior micelle, the QDs can be successfully introduced into an aqueous medium, in which they form an extended hydrogel network. In this form, quantum dots can be utilized in several applications that benefit from their unique properties, such as medical imaging and thermal destruction of malignant cancers. | 0 | Theoretical and Fundamental Chemistry |
Ferredoxins (from Latin ferrum: iron + redox, often abbreviated "fd") are iron–sulfur proteins that mediate electron transfer in a range of metabolic reactions. The term "ferredoxin" was coined by D.C. Wharton of the DuPont Co. and applied to the "iron protein" first purified in 1962 by Mortenson, Valentine, and Carnahan from the anaerobic bacterium Clostridium pasteurianum.
Another redox protein, isolated from spinach chloroplasts, was termed "chloroplast ferredoxin". The chloroplast ferredoxin is involved in both cyclic and non-cyclic photophosphorylation reactions of photosynthesis. In non-cyclic photophosphorylation, ferredoxin is the last electron acceptor thus reducing the enzyme NADP reductase. It accepts electrons produced from sunlight-excited chlorophyll and transfers them to the enzyme ferredoxin: NADP oxidoreductase .
Ferredoxins are small proteins containing iron and sulfur atoms organized as iron–sulfur clusters. These biological "capacitors" can accept or discharge electrons, with the effect of a change in the oxidation state of the iron atoms between +2 and +3. In this way, ferredoxin acts as an electron transfer agent in biological redox reactions.
Other bioinorganic electron transport systems include rubredoxins, cytochromes, blue copper proteins, and the structurally related Rieske proteins.
Ferredoxins can be classified according to the nature of their iron–sulfur clusters and by sequence similarity. | 0 | Theoretical and Fundamental Chemistry |
During photosynthesis, natural electron acceptor NADP is reduced to NADPH in chloroplasts. The following equilibrium reaction takes place.
A reduction reaction that stores energy as NADPH:
: (Reduction)
An oxidation reaction as NADPH's energy is used elsewhere:
: (Oxidation)
Ferredoxin, also known as an NADP+ reductase, is an enzyme that catalyzes the reduction reaction. It is easy to oxidize NADPH but difficult to reduce NADP, hence a catalyst is beneficial. Cytochromes are conjugate proteins that contain a haem group. The iron atom from this group undergoes redox reactions:
: (Reduction)
: (Oxidation)
The light-dependent redox reaction takes place before the light-independent reaction in photosynthesis. | 0 | Theoretical and Fundamental Chemistry |
Paxlovid is a covalent inhibitor of the 3CLpro (Mpro) enzyme. It is in [https://www.pfizer.com/news/press-release/press-release-detail/pfizers-novel-covid-19-oral-antiviral-treatment-candidate Phase III] trials for the early treatment of SARS-CoV-2 infected patients who have not progressed to severe COVID-19 disease, and who do not immediately require hospitalisation. | 1 | Applied and Interdisciplinary Chemistry |
The reaction mechanism for complex III (cytochrome bc1, coenzyme Q: cytochrome C oxidoreductase) is known as the ubiquinone ("Q") cycle. In this cycle four protons get released into the positive "P" side (inter membrane space), but only two protons get taken up from the negative "N" side (matrix). As a result, a proton gradient is formed across the membrane. In the overall reaction, two ubiquinols are oxidized to ubiquinones and one ubiquinone is reduced to ubiquinol. In the complete mechanism, two electrons are transferred from ubiquinol to ubiquinone, via two cytochrome c intermediates.
Overall:
* 2 x QH oxidised to Q
* 1 x Q reduced to QH
* 2 x Cyt c reduced
* 4 x H released into intermembrane space
* 2 x H picked up from matrix
The reaction proceeds according to the following steps:
Round 1:
# Cytochrome b binds a ubiquinol and a ubiquinone.
# The 2Fe/2S center and B heme each pull an electron off the bound ubiquinol, releasing two protons into the intermembrane space.
# One electron is transferred to cytochrome c from the 2Fe/2S centre, whilst another is transferred from the B heme to the B Heme.
# Cytochrome c transfers its electron to cytochrome c (not to be confused with cytochrome c1), and the B Heme transfers its electron to a nearby ubiquinone, resulting in the formation of a ubisemiquinone.
# Cytochrome c diffuses. The first ubiquinol (now oxidised to ubiquinone) is released, whilst the semiquinone remains bound.
Round 2:
# A second ubiquinol is bound by cytochrome b.
# The 2Fe/2S center and B heme each pull an electron off the bound ubiquinol, releasing two protons into the intermembrane space.
# One electron is transferred to cytochrome c from the 2Fe/2S centre, whilst another is transferred from the B heme to the B Heme.
# Cytochrome c then transfers its electron to cytochrome c, whilst the nearby semiquinone produced from round 1 picks up a second electron from the B heme, along with two protons from the matrix.
# The second ubiquinol (now oxidised to ubiquinone), along with the newly formed ubiquinol are released. | 1 | Applied and Interdisciplinary Chemistry |
In terms of the imaginary system, it is a general term for various types of remote sensor systems that acquire remote sensing images of objects without photography. Scanning is usually used for imaging, tape recording or indirect recording on film. According to the structure of the system, the scanning method and the detector parts are roughly divided into:
1. Optomechanical scanning. Such as multi-spectral scanners. The mirror is used to scan the object surface, and the image data is output after being split, detected and photoelectrically converted.
2. Electronic scanning. For example, a return beam guiding TV camera, is an image-side scanning method. The process is optical imaging on the target surface of the light guide, and the signal is amplified and output after being scanned by the electron beam.
3. Robust self-scanning. For example, the photoelectric scanning sensor of the French SPOT satellite is also an image scanning method. The object is imaged by an objective lens on a detector array consisting of a plurality of charge coupled devices (CCDs) that are photoelectrically converted and output.
4. Antenna scanning. Such as side-view radar, which is an active remote sensing imaging system that is a surface scanning method. It transmits the microwave beam through the antenna and receives an echo reflected by the scene, which is demodulated and output. | 0 | Theoretical and Fundamental Chemistry |
The Great Calcite Belt (GCB) refers to a region of the ocean where there are high concentrations of calcite, a mineral form of calcium carbonate. The belt extends over a large area of the Southern Ocean surrounding Antarctica. The calcite in the Great Calcite Belt is formed by tiny marine organisms called coccolithophores, which build their shells out of calcium carbonate. When these organisms die, their shells sink to the bottom of the ocean, and over time, they accumulate to form a thick layer of calcite sediment.
The Great Calcite Belt occurs in areas of the Southern ocean where the calcite compensation depth (CCD) is relatively shallow, meaning that calcite minerals from the shells of marine organisms dissolve at a shallower depth in the water column. This results in a higher concentration of calcium carbonate sediments in the ocean floor, which can be observed in the form of white chalky sediments.
The Great Calcite Belt plays a significant role regulating the global carbon cycle. Calcite is a form of carbon that is removed from the atmosphere and stored in the ocean, which helps to reduce the amount of carbon dioxide in the atmosphere and mitigate the effects of climate change. Recent studies suggest the belt sequesters something between 15 and 30 million tonnes of carbon per year.
Scientists have further interest in the calcite sediments in the belt, which contain valuable information about past climate, ocean currents, ocean chemistry, and marine ecosystems. For example, variations in the CCD depth over time can indicate changes in the amount of carbon dioxide in the atmosphere and the ocean's ability to absorb it. The belt is also home to a diverse range of contemporary marine life, including deep-sea corals and fish that are adapted to the unique conditions found in this part of the ocean. The Great Calcite Belt is a region of elevated summertime upper ocean calcite concentration derived from coccolithophores, despite the region being known for its diatom predominance. The overlap of two major phytoplankton groups, coccolithophores and diatoms, in the dynamic frontal systems characteristic of this region provides an ideal setting to study environmental influences on the distribution of different species within these taxonomic groups. | 0 | Theoretical and Fundamental Chemistry |
Stephen O'Brien (born 27 February 1991) is an Irish Gaelic footballer who plays for the Kenmare Shamrocks club and at senior level for the Kerry county team since 2014. | 1 | Applied and Interdisciplinary Chemistry |
Sweet crude oil has lower sulphur content - lower than 0.5%. It can be refined into kerosene, high-quality diesel, and gasoline. | 0 | Theoretical and Fundamental Chemistry |
NMR spectroscopy is a technique that has been used over the years to study important dynamic aspects of base flipping. This technique allows researchers to determine the physical and chemical properties of atoms and other molecules by utilizing the magnetic properties of atomic nuclei. In addition, NMR can provide a variety of information including structure, reaction states, chemical environment of the molecules, and dynamics. During the DNA base flipping discovery experiment, researchers utilized NMR spectroscopy to investigate the enzyme-induced base flipping of HhaI methyltransferase. In order to accomplish this experiment, two 5-fluorocytosine residues were incorporated into the target and the reference position with the DNA substrate so the F chemical shift analysis could be performed. Once the F chemical shift analysis was evaluated, it was then concluded that the DNA complexes existed with multiple forms of the target 5-fluorocytosine along the base flipping pathway. | 1 | Applied and Interdisciplinary Chemistry |
Ouabain is no longer approved for use in the USA. In France and Germany, however, intravenous ouabain has a long history in the treatment of heart failure, and some continue to advocate its use intravenously and orally in angina pectoris and myocardial infarction despite its poor and variable absorption. The positive properties of ouabain regarding the prophylaxis and treatment of these two indications are documented by several studies. | 0 | Theoretical and Fundamental Chemistry |
The Bioconductor project curates a variety of R packages aimed at integrating omic data:
*[http://bioconductor.org/packages/release/bioc/html/omicade4.html omicade4], for multiple co-inertia analysis of multi omic datasets
*[http://bioconductor.org/packages/release/bioc/html/MultiAssayExperiment.html MultiAssayExperiment], offering a bioconductor interface for overlapping samples
*[http://bioconductor.org/packages/release/bioc/html/IMAS.html IMAS], a package focused on using multi omic data for evaluating alternative splicing
*[http://bioconductor.org/packages/release/bioc/html/bioCancer.html bioCancer], a package for visualization of multiomic cancer data
*[http://bioconductor.org/packages/release/bioc/html/mixOmics.html mixOmics], a suite of multivariate methods for data integration
*[http://bioconductor.org/packages/release/bioc/html/MultiDataSet.html MultiDataSet], a package for encapsulating multiple data sets
The [https://cran.r-project.org/web/packages/RGCCA/ RGCCA package] implements a versatile framework for data integration. This package is freely available on the [https://cran.r-project.org/ Comprehensive R Archive Network (CRAN)].
The OmicTools database further highlights R packages and othertools for multi omic data analysis:
* [http://www.paintomics.org/ PaintOmics], a web resource for visualization of multi-omics datasets
* SIGMA, a Java program focused on integrated analysis of cancer datasets
* iOmicsPASS, a tool in C++ for multiomic-based phenotype prediction
* [https://github.com/mkanai/grimon Grimon], an R graphical interface for visualization of multiomic data
* [https://pypi.org/project/omics_pipe/ Omics Pipe], a framework in Python for reproducibly automating multiomic data analysis | 1 | Applied and Interdisciplinary Chemistry |
In comparison to cationic cyclizations, radical cyclizations avoid issues associated with Wagner-Meerwein rearrangements, do not require strongly acidic conditions, and can be kinetically controlled. Cationic cyclizations are usually thermodynamically controlled. Radical cyclizations are much faster than analogous anionic cyclizations, and avoid β-elimination side reactions. Anionic Michael-type cyclization is an alternative to radical cyclization of activated olefins. Metal-catalyzed cyclization reactions usually require mildly basic conditions, and substrates must be chosen to avoid β-hydride elimination. The primary limitation of radical cyclizations with respect to these other methods is the potential for radical side reactions. | 0 | Theoretical and Fundamental Chemistry |
When calculating thermal expansion it is necessary to consider whether the body is free to expand or is constrained. If the body is free to expand, the expansion or strain resulting from an increase in temperature can be simply calculated by using the applicable coefficient of thermal expansion.
If the body is constrained so that it cannot expand, then internal stress will be caused (or changed) by a change in temperature. This stress can be calculated by considering the strain that would occur if the body were free to expand and the stress required to reduce that strain to zero, through the stress/strain relationship characterised by the elastic or Young's modulus. In the special case of solid materials, external ambient pressure does not usually appreciably affect the size of an object and so it is not usually necessary to consider the effect of pressure changes.
Common engineering solids usually have coefficients of thermal expansion that do not vary significantly over the range of temperatures where they are designed to be used, so where extremely high accuracy is not required, practical calculations can be based on a constant, average, value of the coefficient of expansion. | 0 | Theoretical and Fundamental Chemistry |
Fecal sludge management (FSM) requires safe and hygienic septic tank and pit latrine emptying services, along with the effective treatment of solids and liquids and the reuse of treated produce where possible. It may include a range of options including on-site and offsite treatment, and the dispersal or capture and further processing of the products of the treatment process into such as biogas, compost and energy. | 1 | Applied and Interdisciplinary Chemistry |
This branch of spectroscopy deals with radiation related to atoms that are stripped of several electrons (multiply ionized atoms (MIA), multiply charged ions, highly charged ions). These are observed in very hot plasmas (laboratory or astrophysical) or in accelerator experiments (beam-foil, electron beam ion trap (EBIT)). The lowest exited electron shells of such ions decay into stable ground states producing photons in VUV, EUV and soft X-ray spectral regions (so-called resonance transitions). | 0 | Theoretical and Fundamental Chemistry |
The 2nd millennium BC text Vedas describe a connection between eternal life and gold. A considerable knowledge of metallurgy has been exhibited in a third-century AD text called Arthashastra which provides ingredients of explosives (Agniyoga) and salts extracted from fertile soils and plant remains (Yavakshara) such as saltpetre/nitre, perfume making (different qualities of perfumes are mentioned), granulated (refined) Sugar. Buddhist texts from the 2nd to 5th centuries mention the transmutation of base metals to gold. According to some scholars Greek alchemy may have influenced Indian alchemy but there are no hard evidences to back this claim.
The 11th-century Persian chemist and physician Abū Rayhān Bīrūnī, who visited Gujarat as part of the court of Mahmud of Ghazni, reported that they
The goals of alchemy in India included the creation of a divine body (Sanskrit divya-deham) and immortality while still embodied (Sanskrit jīvan-mukti). Sanskrit alchemical texts include much material on the manipulation of mercury and sulphur, that are homologized with the semen of the god Śiva and the menstrual blood of the goddess Devī.
Some early alchemical writings seem to have their origins in the Kaula tantric schools associated to the teachings of the personality of Matsyendranath. Other early writings are found in the Jaina medical treatise Kalyāṇakārakam of Ugrāditya, written in South India in the early 9th century.
Two famous early Indian alchemical authors were Nāgārjuna Siddha and Nityanātha Siddha. Nāgārjuna Siddha was a Buddhist monk. His book, Rasendramangalam, is an example of Indian alchemy and medicine. Nityanātha Siddha wrote Rasaratnākara, also a highly influential work. In Sanskrit, rasa translates to "mercury", and Nāgārjuna Siddha was said to have developed a method of converting mercury into gold.
Scholarship on Indian alchemy is in the publication of The Alchemical Body by David Gordon White.
A modern bibliography on Indian alchemical studies has been written by White.
The contents of 39 Sanskrit alchemical treatises have been analysed in detail in G. Jan Meulenbelds History of Indian Medical Literature. The discussion of these works in HIML gives a summary of the contents of each work, their special features, and where possible the evidence concerning their dating. Chapter 13 of HIML, Various works on rasaśāstra and ratnaśāstra (or Various works on alchemy and gems') gives brief details of a further 655 (six hundred and fifty-five) treatises. In some cases Meulenbeld gives notes on the contents and authorship of these works; in other cases references are made only to the unpublished manuscripts of these titles.
A great deal remains to be discovered about Indian alchemical literature. The content of the Sanskrit alchemical corpus has not yet (2014) been adequately integrated into the wider general history of alchemy. | 1 | Applied and Interdisciplinary Chemistry |
Time-domain diffuse optical sources must have the following characteristics; emission wavelength in the optical window i.e. between 650 and 1350 nanometre (nm); a narrow full width at half maximum (FWHM), ideally a delta function; high repetition rate (>20 MHz) and finally, sufficient laser power (>1 mW) to achieve good signal to noise ratio.
In the past bulky tunable Ti:sapphire Lasers were used. They provided a wide wavelength range of 400 nm, a narrow FWHM (< 1 ps) high average power (up to 1W) and high repetition (up to 100 MHz) frequency. However, they are bulky, expensive and take a long time for wavelength swapping.
In recent years, pulsed fiber lasers based on super continuum generation have emerged. They provide a wide spectral range (400 to 2000 ps), typical average power of 5 to 10 W, a FWHM of < 10ps and a repetition frequency of tens of MHz. However, they are generally quite expensive and lack stability in super continuum generation and hence, have been limited in there use.
The most wide spread sources are the pulsed diode lasers. They have a FWHM of around 100 ps and repetition frequency of up to 100 MHz and an average power of about a few milliwatts. Even though they lack tunability, their low cost and compactness allows for multiple modules to be used in a single system. | 0 | Theoretical and Fundamental Chemistry |
The following have received a medal:
*2022: Michael Tarbutt, for pioneering experimental and theoretical work on the production of ultracold molecules by laser cooling, and the applications of those molecules to quantum science and tests of fundamental physics.
*2021: Carla Faria, for distinguished contributions to the theory of strong-field laser-matter interactions.
*2020: Michael Charlton, for scientific leadership in antimatter science.
*2019: , for outstanding contributions to experiments on ultra-cold atoms and molecules
*2016: Jeremy M. Hutson, for his pioneering work on the theory of ultracold molecules
*2014: Charles S Adams, for his imaginative experiments which have pioneered the field of Rydberg quantum optics
*2012: , for his pioneering experimental work in Bose-Einstein condensates and cold Fermi gases
*2010: , for her contributions to the development of the worlds only positronium beam'
*2008: Edward Hinds, for his important and elegant experimental investigations in the fields of atomic physics and quantum optics | 0 | Theoretical and Fundamental Chemistry |
Because of the great importance of many types of CIA spectra in planetary and astrophysical research, a well known spectroscopy database (HITRAN) has been expanded to include a number of CIA spectra in various frequency bands and for a variety of temperatures. | 0 | Theoretical and Fundamental Chemistry |
Although there may not be a precise elucidation of pancratistatin biological synthesis, there have been speculations on biosynthesis of narciclasine and lycoricidine that are very similar to pancratistatin in terms of structure. The biosynthesis is accomplished via synthesis from O-methylnorbelladine by para-para phenol coupling to obtain vittatine as an intermediate. Subsequent elimination of two carbon atoms and hydroxylations of vittatine then leads to narciclasine. | 0 | Theoretical and Fundamental Chemistry |
In 1971, Akira Endo, a Japanese biochemist working for the pharmaceutical company Sankyo, identified mevastatin (ML-236B), a molecule produced by the fungus Penicillium citrinum, as an inhibitor of HMG-CoA reductase, a critical enzyme used by the body to produce cholesterol. Animal trials showed very good inhibitory effect as in clinical trials, however a long-term study in dogs found toxic effects at higher doses and as a result mevastatin was believed to be too toxic for human use. Mevastatin was never marketed, because of its adverse effects of tumors, muscle deterioration, and sometimes death in laboratory dogs.
P. Roy Vagelos, chief scientist and later CEO of Merck & Co, was interested, and made several trips to Japan starting in 1975. By 1978, Merck had isolated lovastatin (mevinolin, MK803) from the fungus Aspergillus terreus, first marketed in 1987 as Mevacor.
In April 1994, the results of a Merck-sponsored study, the Scandinavian Simvastatin Survival Study, were announced. Researchers tested simvastatin, later sold by Merck as Zocor, on 4,444 patients with high cholesterol and heart disease. After five years, the study concluded the patients saw a 35% reduction in their cholesterol, and their chances of dying of a heart attack were reduced by 42%. In 1995, Zocor and Mevacor both made Merck over US$1 billion. Endo was awarded the 2006 Japan Prize, and the Lasker-DeBakey Clinical Medical Research Award in 2008. For his "pioneering research into a new class of molecules" for "lowering cholesterol," | 1 | Applied and Interdisciplinary Chemistry |
One of the most important components of DSSC is the counter electrode. As stated before, the counter electrode is responsible for collecting electrons from the external circuit and introducing them back into the electrolyte to catalyze the reduction reaction of the redox shuttle, generally I to I. Thus, it is important for the counter electrode to not only have high electron conductivity and diffusive ability, but also electrochemical stability, high catalytic activity and appropriate band structure. The most common counter electrode material currently used is platinum in DSSCs, but is not sustainable owing to its high costs and scarce resources. Thus, much research has been focused towards discovering new hybrid and doped materials that can replace platinum with comparable or superior electrocatalytic performance. One such category being widely studied includes chalcogen compounds of cobalt, nickel, and iron (CCNI), particularly the effects of morphology, stoichiometry, and synergy on the resulting performance. It has been found that in addition to the elemental composition of the material, these three parameters greatly impact the resulting counter electrode efficiency. Of course, there are a variety of other materials currently being researched, such as highly mesoporous carbons, tin-based materials, gold nanostructures, as well as lead-based nanocrystals. However, the following section compiles a variety of ongoing research efforts specifically relating to CCNI towards optimizing the DSSC counter electrode performance. | 0 | Theoretical and Fundamental Chemistry |
A CHN analyzer (also known as a carbon hydrogen and nitrogen analyzer) is a scientific instrument which is used to measure carbon, hydrogen and nitrogen elemental concentrations in a given sample with accuracy and precision. Sample sizes are most often just a few milligrams, but may differ depending on system. For some sample matrices larger mass is preferred due to sample heterogeneity. These analysers are capable of handling a wide variety of sample types, including solids, liquids, volatile and viscous samples, in the fields of pharmaceuticals, polymers, chemicals, environment, food and energy.
This instrument calculates the percentages of elemental concentrations based on the Dumas method, using flash combustion of the sample to cause an instantaneous oxidization into simple compounds which are then detected with thermal conductivity detection or infrared spectroscopy. Separation of interference is done by chemical reagents. | 0 | Theoretical and Fundamental Chemistry |
Charles Thomas Beer (18 November 1915 – 15 June 2010) was a Canadian organic chemist who helped in the discovery of vinblastine.
Born in Leigh, Dorset, England, he received a D.Phil. in chemistry from Oxford in 1948. He came to North America in the early 1950s to the department of medical research at the University of Western Ontario to work with Robert L. Noble. Together they isolated the anti-cancer drug vinblastine from the leaves of the Madagascar periwinkle plant (vinca rosea) at the University of Western Ontario in 1958. The discovery of vinblastine is generally considered a milestone in the development of chemotherapy.
In 1960, he became professor of biochemistry at the University of British Columbia. After his retirement, he remained an honorary senior research scientist in the department of cancer endocrinology at the British Columbia Cancer Agency.
In 1997, he was inducted into the Canadian Medical Hall of Fame. In 2003, he was made a Member of the Order of Canada | 0 | Theoretical and Fundamental Chemistry |
Unlike gases or liquids, solid materials tend to keep their shape when undergoing thermal expansion.
Thermal expansion generally decreases with increasing bond energy, which also has an effect on the melting point of solids, so high melting point materials are more likely to have lower thermal expansion. In general, liquids expand slightly more than solids. The thermal expansion of glasses is slightly higher compared to that of crystals. At the glass transition temperature, rearrangements that occur in an amorphous material lead to characteristic discontinuities of coefficient of thermal expansion and specific heat. These discontinuities allow detection of the glass transition temperature where a supercooled liquid transforms to a glass.
Absorption or desorption of water (or other solvents) can change the size of many common materials; many organic materials change size much more due to this effect than due to thermal expansion. Common plastics exposed to water can, in the long term, expand by many percent. | 0 | Theoretical and Fundamental Chemistry |
After time is allowed for binding with the oligonucleotide probes, the hope is that some of the proteins on the membrane filter have bound to the probes. Any probe that was not able to bind a protein needs to be removed. Once unbound probe removal has been taken care of, to better visualize the membrane filter, it is subjected to further varying procedures. By corresponding the resulting membrane filter to the second membrane filter that the gel was sandwiched between, the position of the protein in comparison to the molecular weight ladder gives information about the weight of the protein that bound to the probe. | 1 | Applied and Interdisciplinary Chemistry |
Pipelines can help ensure a country's economic well-being and as such present a likely target of terrorists or wartime adversaries.
Fossil fuels can be transported by pipeline, rail, truck or ship, though natural gas requires compression or liquefaction to make vehicle transport economical. For transport of crude oil via these four modes, various reports rank pipelines as proportionately causing less human death and property damage than rail and truck and spilling less oil than truck. | 1 | Applied and Interdisciplinary Chemistry |
Based on the manual curation done, BioCyc database family is divided into 3 tiers:
Tier 1: Databases which have received at least one year of literature based manual curation. Currently there are seven databases in Tier 1. Out of the seven, MetaCyc is a major database that contains almost 2500 metabolic pathways from many organisms. The other important Tier 1 database is HumanCyc which contains around 300 metabolic pathways found in humans. The remaining five databases include, EcoCyc (E. coli), AraCyc (Arabidopsis thaliana), YeastCyc (Saccharomyces cerevisiae), LeishCyc (Leishmania major Friedlin) and TrypanoCyc (Trypanosoma brucei).
Tier 2: Databases that were computationally predicted but have received moderate manual curation (most with 1–4 months curation). Tier 2 Databases are available for manual curation by scientists who are interested in any particular organism. Tier 2 databases currently contain 43 different organism databases.
Tier 3: Databases that were computationally predicted by PathoLogic and received no manual curation. As with Tier 2, Tier 3 databases are also available for curation for interested scientists. | 1 | Applied and Interdisciplinary Chemistry |
When interatom bonding does not have strong directional preferences, it is not unusual for atoms to gravitate toward a kissing number of 12 nearest neighbors. The three most symmetric ways to do this are by icosahedral clustering, by crystalline face-centered-cubic (cuboctahedral) and hexagonal (tri-orthobicupolar) close packing.
Icosahedral arrangements, typically because of their smaller surface energy, may be preferred for small clusters. However, the Achilles' heel for icosahedral clustering is that it cannot fill space over large distances in a way that is translationally ordered, so there is some distortion of the atomic positions, that is elastic strain. De Wit pointed out that these can be thought of in terms of disclinations, an approach later extended to 3D by Yoffe. The shape is also not always that of a simple icosahedron, and there are now several software codes that make it easy to calculate the shape.
At larger sizes the energy to distort becomes larger than the gain in surface energy, and bulk materials (i.e. sufficiently large clusters) generally revert to one of the crystalline close-packing configurations. In principle they will convert to a simple single crystal with a Wulff construction shape. The size when they become less energetically stable is typically in the range of 10-30 nanometers in diameter, but it does not always happen that the shape changes and the particles can grow to millimeter sizes. | 0 | Theoretical and Fundamental Chemistry |
When a splice site mutation occurs in intron 2 of the gene that produces the parathyroid hormone, a parathyroid deficiency can prevail. In one particular study, a G to C substitution in the splice site of intron 2 produces a skipping effect in the messenger RNA transcript. The exon that is skipped possesses the initiation start codon to produce parathyroid hormone. Such failure in initiation causes the deficiency. | 1 | Applied and Interdisciplinary Chemistry |
By the time of the American Civil War, as telegraph traffic increased, the Grove cell's tendency to discharge poisonous nitrogen dioxide (NO) fumes proved increasingly hazardous to health, and as telegraphs became more complex, the need for constant voltage became critical. The Grove cell was limited in this respect, because as the cell discharged, voltage reduced. Eventually, Grove cells were replaced in use by Daniell cells. | 0 | Theoretical and Fundamental Chemistry |
An individual signal transduction pathway can regulate several proteins (e.g. kinases) as well as the activation of many genes. The consequences to the properties of the cell can be, therefore, very prominent. Identifying these properties (through theoretical predictions and experimentation) sheds light on the function of the pathway and provides possible new therapeutic targets.
Activation of the notch/STAT3-Ser/Hes3 signaling axis has significant consequences to several cell types; effects have been documented both in vitro and in vivo:
:* Cultured fetal and adult rodent neural stem cells: Pro-survival effects; increased yield; increased expression of sonic hedgehog protein.
:* In vivo adult rodent neural stem cells: Increase in cell number; increased expression of Sonic hedgehog (Shh) protein. Delta4 administration in the adult rodent brain has also been shown to augment the effect of basic fibroblast growth factor and epidermal growth factor in promoting the proliferation of neural precursor cells in the subventricular zone and hypothalamus following ischemic stroke.
:* Cultured adult monkey neural stem cells: Pro-survival effects; increased yield; increased expression of sonic hedgehog protein.
:* Cultured putative glioblastoma multiforme cancer stem cells: Pro-survival effects (Hes3 knockdown by RNA interference reduces cell number).
:* Cultured bovine chromaffin progenitor cells: Several activators of the signaling pathway increase cell yield.
:* Cultured mouse insulinoma cells (MIN6 cell line): These cells can be cultured efficiently under conditions that promote the operation of the signaling pathway; Hes3 RNA interference opposes growth and the release of insulin following standard protocols that evoke insulin release from these cells.
:* Mice that are engineered to lack the Hes3 gene exhibit increased sensitivity to treatments that damage endocrine pancreas cells.
:* Recent research implicates Hes3 in direct reprogramming of adult mouse cells to the neural stem cell state; a causative relation remains to be determined.
:* Hes3 and components of the Signaling Axis are regulated during critical stages of reprogramming (Mouse Embryonic Fibroblast - to - Embryonic Stem Cell reprogramming).
:* Mice genetically engineered to lack the Hes3 gene fail to upregulate the transcription factor Neurogenin3 during pancreatic regeneration (induced by streptozotocin treatment). This is indicative of a compromised regenerative response. | 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.