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Levan can be used for hair care and skin whitening. In hair care products, levan acts to form a film which creates a hair holding effect utilized in various gels and mousses. Levan is used as a skin whitener as well because it has been tested to show inhibition on melanin production by decreasing the activity of the enzyme tyrosinase which is responsible for melanogenesis. | 1 | Applied and Interdisciplinary Chemistry |
Sub-cellular fractions of photosynthetic organisms, such as purified thylakoid membranes, can also be used in biological photovoltaic systems. A benefit of using material that contains both photosystem II and photosystem I is that electrons extracted from water by photosystem II can be donated to the anode at a more negative redox potential (from the reductive end of photosystem I). A redox mediator (e.g. ferricyanide) is required to transfer electrons between the photosynthetic components and the anode. | 0 | Theoretical and Fundamental Chemistry |
* Decroocq, S and Casserino, M, Polybutenes, Chapter 17 in Rudnick (Ed), Synthetics, Mineral Oils, and Bio-Based Lubricants: Chemistry and Technology, CRC Press (2005), Print , eBook . | 0 | Theoretical and Fundamental Chemistry |
Consider two uniform distributions, with the support of enclosed within (). Then the information gain is:
Intuitively, the information gain to a times narrower uniform distribution contains bits. This connects with the use of bits in computing, where bits would be needed to identify one element of a long stream. | 0 | Theoretical and Fundamental Chemistry |
Although there are many other molecular display technologies, such as phage display, bacterial display, yeast display, and ribosome display, mRNA display technology has many advantages over the others. The first three biological display libraries listed have polypeptides or proteins expressed on the respective microorganism’s surface and the accompanying coding information for each polypeptide or protein is retrievable from the microorganism’s genome. However, the library size for these three in vivo display systems is limited by the transformation efficiency of each organism. For example, the library size for phage and bacterial display is limited to 1-10 × 10^9 different members. The library size for yeast display is even smaller. Moreover, these cell-based display system only allow the screening and enrichment of peptides/proteins containing natural amino acids. In contrast, mRNA display and ribosome display are in vitro selection methods. They allow a library size as large as 10^15 different members. The large library size increases the probability to select very rare sequences, and also improves the diversity of the selected sequences. In addition, in vitro selection methods remove unwanted selection pressure, such as poor protein expression, and rapid protein degradation, which may reduce the diversity of the selected sequences. Finally, in vitro selection methods allow the application of in vitro mutagenesis and recombination techniques throughout the selection process.
Although both ribosome display and mRNA display are in vitro selection methods, mRNA display has some advantage over the ribosome display technology. mRNA display utilizes covalent mRNA-polypeptide complexes linked through puromycin; whereas, ribosome display utilizes stalled, noncovalent ribosome-mRNA-polypeptide complexes. For ribosome display, selection stringency is limited to keep ribosome-mRNA-polypeptide in a complex because of the noncovalent ribosome-mRNA-polypeptide complexes. This may cause difficulties in reducing background binding during the selection cycle. Also, the polypeptides under selection in a ribosome display system are attached to an enormous rRNA-protein complex, a ribosome, which has a molecular weight of more than 2,000,000 Da. There might be some unpredictable interaction between the selection target and the ribosome, and this may lead to a loss of potential binders during the selection cycle. In contrast, the puromycin DNA spacer linker used in mRNA display technology is much smaller comparing to a ribosome. This linker may have less chance to interact with an immobilized selection target. Thus, mRNA display technology is more likely to give less biased results. | 1 | Applied and Interdisciplinary Chemistry |
Lithium tert-butoxide is commercially available as a solution and as a solid, but it is often generated in situ for laboratory use because samples are so sensitive and older samples are often of poor quality. It can be obtained by treating tert-butanol with butyl lithium. | 0 | Theoretical and Fundamental Chemistry |
DNA is a major example of a supramolecular polymer. protein Much effort has been develoted to related but synthetic materials. At the same time, their reversible and dynamic nature make supramolecular polymers bio-degradable, which surmounts hard-to-degrade issue of covalent polymers and makes supramolecular polymers a promising platform for biomedical applications. Being able to degrade in biological environment lowers potential toxicity of polymers to a great extent and therefore, enhances biocompatibility of supramolecular polymers. | 0 | Theoretical and Fundamental Chemistry |
*Karl Jasmund, Gerhard Lagaly (editors): Tonminerale und Tone. Struktur, Eigenschaften, Anwendungen und Einsatz in Industrie und Umwelt. Steinkopf Verlag, Darmstadt, 1993.
*Gerhard Lagaly, Oliver Schulz, Ralf Zimehl: Dispersionen und Emulsionen: eine Einführung in die Kolloidik feinverteilter Stoffe einschließlich der Tonminerale, Steinkopf Verlag, Darmstadt, 1997.
* Faiza Bergaya, Gergard Lagaly (editors): Handbook of Clay Science. Elsevier, Amsterdam, 2013 (2nd Ed.). | 0 | Theoretical and Fundamental Chemistry |
*Structure and Matter, 20%
* States of Matter, 20%
* Reactions, 35–40%
* Descriptive Chemistry, 10–15%
* Laboratory, 5–10% | 1 | Applied and Interdisciplinary Chemistry |
Chelating agents, natural zeolite, activated carbon, resins, and liquid organics impregnated with chelating agents are all used to exchange cations or anions with the solution. Selectivity and recovery are a function of the reagents used and the contaminants present. | 1 | Applied and Interdisciplinary Chemistry |
Pitch is a viscoelastic polymer which can be natural or manufactured, derived from petroleum, coal tar, or plants. Pitch produced from petroleum may be called bitumen or asphalt, while plant-derived pitch, a resin, is known as rosin in its solid form. Tar is sometimes used interchangeably with pitch, but generally refers to a more liquid substance derived from coal production, including coal tar, or from plants, as in pine tar. | 0 | Theoretical and Fundamental Chemistry |
The main drawback of the aperture mode is that the small aperture size reduces the signal intensity and is difficult to fabricate. Recently, researchers have focused on the apertureless mode, which utilizes SPR theory to produce stronger signals. There are two techniques supporting this mode: SERS and TERS. | 0 | Theoretical and Fundamental Chemistry |
DRAM-v is the standard for AMG annotation of metagenome assembled genomes (MAGs) identified as viruses. DRAM-v searches the following databases for AMGs that match the input MAGs: Pfam, KEGG, UniProt, CAZy, MEROPS, VOGDB, and NCBI Viral RefSeq. KEGG can then be referenced to classify annotated AMGs through VIBRANT. | 1 | Applied and Interdisciplinary Chemistry |
* King Chandra and the Mehrauli Pillar, M.C. Joshi, S.K. Gupta and Shankar Goyal, Eds., Kusumanjali Publications, Meerut, 1989.
* The Rustless Wonder – A Study of the Iron Pillar at Delhi, T.R. Anantharaman, Vigyan Prasar New Delhi, 1996.
* Delhi Iron Pillar: New Insights. R. Balasubramaniam, Aryan Books International, Delhi, and Indian Institute of Advanced Study, Shimla, 2002, Hardbound, . [http://www.infinityfoundation.com/mandala/t_rv/t_rv_agraw_delhi_frameset.htm] [http://home.iitk.ac.in/~bala/journalpaper/journal/index.htm]
* The Delhi Iron Pillar: Its Art, Metallurgy and Inscriptions, M.C. Joshi, S.K. Gupta and Shankar Goyal, Eds., Kusumanjali Publications, Meerut, 1996.
* The World Heritage Complex of the Qutub, R. Balasubramaniam, Aryan Books International, New Delhi, 2005, Hardbound, .
* "Delhi Iron Pillar" (in two parts), R. Balasubramaniam, IIM Metal News Volume 7, No. 2, April 2004, pp. 11–17 and IIM Metal News Volume 7, No. 3, June 2004, pp. 5–13. [http://home.iitk.ac.in/%7Ebala/journalpaper/popart_6_7/metalnews_2004.pdf]
* [http://home.iitk.ac.in/%7Ebala/journalpaper/journal/journalpaper_20.pdf New Insights on the 1600-Year Old Corrosion Resistant Delhi Iron Pillar], R. Balasubramaniam, Indian Journal of History of Science 36 (2001) 1–49.
* The Early use of Iron in India, Dilip K. Chakrabarti, Oxford University Press, New Delhi, 1992, . | 1 | Applied and Interdisciplinary Chemistry |
One application of the Weber number is the study of heat pipes. When the momentum flux in the vapor core of the heat pipe is high, there is a possibility that the shear stress exerted on the liquid in the wick can be large enough to entrain droplets into the vapor flow. The Weber number is the dimensionless parameter that determines the onset of this phenomenon called the entrainment limit (Weber number greater than or equal to 1). In this case the Weber number is defined as the ratio of the momentum in the vapor layer divided by the surface tension force restraining the liquid, where the characteristic length is the surface pore size. | 1 | Applied and Interdisciplinary Chemistry |
Protein production is the biotechnological process of generating a specific protein. It is typically achieved by the manipulation of gene expression in an organism such that it expresses large amounts of a recombinant gene. This includes the transcription of the recombinant DNA to messenger RNA (mRNA), the translation of mRNA into polypeptide chains, which are ultimately folded into functional proteins and may be targeted to specific subcellular or extracellular locations.
Protein production systems (also known as expression systems) are used in the life sciences, biotechnology, and medicine. Molecular biology research uses numerous proteins and enzymes, many of which are from expression systems; particularly DNA polymerase for PCR, reverse transcriptase for RNA analysis, restriction endonucleases for cloning, and to make proteins that are screened in drug discovery as biological targets or as potential drugs themselves. There are also significant applications for expression systems in industrial fermentation, notably the production of biopharmaceuticals such as human insulin to treat diabetes, and to manufacture enzymes. | 1 | Applied and Interdisciplinary Chemistry |
PA is a unique phospholipid in that it has a small highly charged head group that is very close to the glycerol backbone. PA is known to play roles in both vesicle fission and fusion, and these roles may relate to the biophysical properties of PA.
At sites of membrane budding or fusion, the membrane becomes or is highly curved. A major event in the budding of vesicles, such as transport carriers from the Golgi, is the creation and subsequent narrowing of the membrane neck. Studies have suggested that this process may be lipid-driven, and have postulated a central role for DAG due to its, likewise, unique molecular shape. The presence of two acyl chains but no headgroup results in a large negative curvature in membranes.
The LPAAT BARS-50 has also been implicated in budding from the Golgi. This suggests that the conversion of lysoPA into PA might affect membrane curvature. LPAAT activity doubles the number of acyl chains, greatly increasing the cross-sectional area of the lipid that lies ‘within’ the membrane while the surface headgroup remains unchanged. This can result in a more negative membrane curvature. Researchers from Utrecht University have looked at the effect of lysoPA versus PA on membrane curvature by measuring the effect these have on the transition temperature of PE from lipid bilayers to nonlamellar phases using P-NMR. The curvature induced by these lipids was shown to be dependent not only on the structure of lysoPA versus PA but also on dynamic properties, such as the hydration of head groups and inter- and intramolecular interactions. For instance, Ca may interact with two PAs to form a neutral but highly curved complex. The neutralisation of the otherwise repulsive charges of the headgroups and the absence of any steric hindrance enables strong intermolecular interactions between the acyl chains, resulting in PA-rich microdomains. Thus in vitro, physiological changes in pH, temperature, and cation concentrations have strong effects on the membrane curvature induced by PA and lysoPA.
The interconversion of lysoPA, PA, and DAG – and changes in pH and cation concentration – can cause membrane bending and destabilisation, playing a direct role in membrane fission simply by virtue of their biophysical properties. However, though PA and lysoPA have been shown to affect membrane curvature in vitro; their role in vivo is unclear.
The roles of lysoPA, PA, and DAG in promoting membrane curvature do not preclude a role in recruiting proteins to the membrane. For instance, the Ca requirement for the fusion of complex liposomes is not greatly affected by the addition of annexin I, though it is reduced by PLD. However, with annexin I and PLD, the extent of fusion is greatly enhanced, and the Ca requirement is reduced almost 1000-fold to near physiological levels.
Thus the metabolic, biophysical, recruitment, and signaling roles of PA may be interrelated. | 1 | Applied and Interdisciplinary Chemistry |
Enzyme promiscuity is the ability of an enzyme to catalyse a fortuitous side reaction in addition to its main reaction. Although enzymes are remarkably specific catalysts, they can often perform side reactions in addition to their main, native catalytic activity. These promiscuous activities are usually slow relative to the main activity and are under neutral selection. Despite ordinarily being physiologically irrelevant, under new selective pressures these activities may confer a fitness benefit therefore prompting the evolution of the formerly promiscuous activity to become the new main activity. An example of this is the atrazine chlorohydrolase (atzA encoded) from Pseudomonas sp. ADP that evolved from melamine deaminase (triA encoded), which has very small promiscuous activity toward atrazine, a man-made chemical. | 1 | Applied and Interdisciplinary Chemistry |
Sir Robert Howson Pickard FRS (27 September 1874 – 18 October 1949) was a chemist who did pioneering work in stereochemistry and also for the cotton industry in Lancashire. He was also involved in educational administration and was Vice Chancellor of the University of London from 1937-1939. He was Principal of Battersea Polytechnic (which later became the University of Surrey) from 1920 to 1927. | 0 | Theoretical and Fundamental Chemistry |
Gene sequence-based methods depend on the recognition of exclusive gene sequences particular to specific strains of organisms. Polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH) are gene sequence-based methods currently being used to detect specific strains of indicator bacteria. | 0 | Theoretical and Fundamental Chemistry |
Carbon has 2 stable isotopes, carbon-12 (C) and carbon-13 (C). The ratio between the two is denoted , and represents a number of factors.
Because organic matter preferentially takes up the lighter C, an increase in productivity increases the of the rest of the system, and vice versa. Some carbon reservoirs are very isotopically light: for instance, biogenic methane, produced by bacterial decomposition, has a of −60‰ – vast, when 1‰ is a large fluctuation! An injection of carbon from one of these reservoirs could therefore account for the early Cambrian drop in .
Causes often suggested for changes in the ratio of C to C found in rocks include:
* A mass extinction. Chemistry is largely driven by electro-magnetic forces, and lighter isotopes such as C respond to these more quickly than heavier ones such as C. So living organisms generally contain a disproportionate amount of C. A mass extinction would increase the amount of C available to be included in rocks and therefore reduce the ratio of C to C.
* A methane “burp”. In permafrosts and continental shelves methane produced by bacteria gets trapped in “cages” of water molecules, forming a mixture called a clathrate. This methane is very rich in C because it has been produced by organisms. Clathrates may dissociate (break up) suddenly if the temperature rises or the pressure on them drops. Such dissociations release the C-rich methane and thus reduce the ratio of C to C as this carbon is gradually incorporated into rocks (methane in the atmosphere breaks down into carbon dioxide and water; carbon dioxide reacts with minerals to form carbonate rocks). | 0 | Theoretical and Fundamental Chemistry |
In 2011, a record outbreak of blooming microcystis occurred in Lake Erie, in part related to the wettest spring on record, and expanded lake bottom dead zones, reduced fish populations, fouled beaches, and damaged the local tourism industry, which generates more than $10 billion in revenue annually.
In August 2014, the City of Toledo, Ohio detected unsafe levels of microcystin in its water supply due to harmful algal blooms in Lake Erie, the shallowest of the Great Lakes. The city issued an advisory to approximately 500,000 people that the water was not safe for drinking or cooking. An Ohio state task force found that Lake Erie received more phosphorus than any other Great Lake, both from crop land, due to the farming practices, and from urban water-treatment centres. | 1 | Applied and Interdisciplinary Chemistry |
Although glyceroneogenesis was first found in adipose tissues, it was not recognized in the liver until 1998. This finding was unexpected because triglyceride synthesis in the liver was thought not to occur due to the amount of gluconeogenesis taking place, and because the liver was believed to have sufficient glycerol 3-phosphate collected from the bloodstream. Several experiments using stable isotopes to track the glycerol in the liver and bloodstream, showed that 65% of the glycerol backbone of triglycerides in the bloodstream is synthesized in the liver. It was subsequently found that the liver synthesizes more than half of the glycerol mammals need to regulate lipids.
Glyceroneogenesis in the liver and adipose tissues regulate lipid metabolism in opposite ways. Lipids as triglycerides are released from the liver, while glyceroneogenesis restrains the fatty acid release from adipose tissues by re-esterifying them. When the lipid concentration in the blood is relatively high, glyceroneogenesis in the liver will be down-regulated to stop the synthesis of triglycerides, but glyceroneogenesis in adipose tissues will be induced in order to restrain the release of free fatty acid to the bloodstream. Conversely, glyceroneogenesis is induced in the liver and suppressed in adipose tissues when the blood lipid level is low. Although the reciprocal regulation of glyceroneogenesis is not well understood, a hormone called glucocorticoid is involved in the regulation. Glucocorticoids induce gene transcription of PEPC-K in liver but repress the transcription in adipose tissues. | 1 | Applied and Interdisciplinary Chemistry |
Phosphonate esters are generally susceptible to hydrolysis under both acidic and basic conditions. Cleavage of the P-C bond is harder but can be achieved under aggressive conditions.
:O=PC(OR) + 2 HO → O=PC(OH) + 2 ROH | 0 | Theoretical and Fundamental Chemistry |
Triplet fluorenylidene reacts with olefins in a stepwise fashion to produce a racemic mixture, provided that the rate of spin inversion (intersystem crossing) is not significantly faster than rates of intermediate bond rotation. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, Möbius aromaticity is a special type of aromaticity believed to exist in a number of organic molecules. In terms of molecular orbital theory these compounds have in common a monocyclic array of molecular orbitals in which there is an odd number of out-of-phase overlaps, the opposite pattern compared to the aromatic character to Hückel systems. The nodal plane of the orbitals, viewed as a ribbon, is a Möbius strip, rather than a cylinder, hence the name. The pattern of orbital energies is given by a rotated Frost circle (with the edge of the polygon on the bottom instead of a vertex), so systems with 4n electrons are aromatic, while those with 4n + 2 electrons are anti-aromatic/non-aromatic. Due to incrementally twisted nature of the orbitals of a Möbius aromatic system, stable Möbius aromatic molecules need to contain at least 8 electrons, although 4 electron Möbius aromatic transition states are well known in the context of the Dewar-Zimmerman framework for pericyclic reactions. Möbius molecular systems were considered in 1964 by Edgar Heilbronner by application of the Hückel method, but the first such isolable compound was not synthesized until 2003 by the group of Rainer Herges. However, the fleeting trans-CH cation, one conformation of which is shown on the right, was proposed to be a Möbius aromatic reactive intermediate in 1998 based on computational and experimental evidence. | 0 | Theoretical and Fundamental Chemistry |
Oxidative phosphorylation produces 26 of the 30 equivalents of ATP generated in cellular respiration by transferring electrons from NADH or FADH2 to O through electron carriers. The energy released when electrons are passed from higher-energy NADH or FADH2 to the lower-energy O is required to phosphorylate ADP and once again generate ATP. It is this energy coupling and phosphorylation of ADP to ATP that gives the electron transport chain the name oxidative phosphorylation. | 1 | Applied and Interdisciplinary Chemistry |
Based on the properties of intercalating molecules, i.e. fluorescing upon binding to DNA and unwinding of DNA base-pairs, in 2016, a single-molecule technique has been introduced to directly visualize individual plectonemes along supercoiled DNA which would further allow to study the interactions of DNA processing proteins with supercoiled DNA. In that study, Sytox Orange (an intercalating dye) was used to induce supercoiling on surface tethered DNA molecules.
Using this assay, it was found that the DNA sequence encodes for the position of plectonemic supercoils. Furthermore, DNA supercoils were found to be enriched at the transcription start sites in prokaryotes. | 1 | Applied and Interdisciplinary Chemistry |
T5 retrofit conversion is a means of converting light fittings designed to use T8 format lamps, so that they can use more energy-efficient T5 lamps. This is done by electronically converting the luminaires to high frequency operation. | 1 | Applied and Interdisciplinary Chemistry |
Steroid 21-hydroxylase, is a member of the cytochrome P450 family of monooxygenase enzymes, the protein has 494 amino acid residues with a molecular weight of 55,000. This enzyme is at most 28% homologous to other P-450 enzymes that have been studied.
Structurally, the protein contains an evolutionarily conserved core of four α-helix bundles (the importance of such genetic conservation is in demonstrating the functional importance of this aspect of this protein's structure). In addition, it has two additional alpha helices, two sets of β-sheets, and a heme cofactor binding loop. Each subunit in the human enzyme consists of a total of 13 α-helices and 9 β-strands that folds into a triangular prism-like tertiary structure.
The iron(III) heme group that defines the active site resides in the center of each subunit. The human enzyme binds one substrate at a time. In contrast, the well-characterized bovine enzyme can bind two substrates. The human and bovine enzyme share 80% amino acid sequence identity, but are structurally different, particularly in loop regions, and also evident in secondary structure elements. | 1 | Applied and Interdisciplinary Chemistry |
Although it is relatively simple to demonstrate that the electron and proton begin and end in different orbitals, it is more difficult to prove that they do not move sequentially. The main evidence that PCET exists is that a number of reactions occur faster than expected for the sequential pathways. In the initial electron transfer (ET) mechanism, the initial redox event has a minimum thermodynamics barrier associate with the first step. Similarly, the initial proton transfer (PT) mechanism has a minimum barrier associated with the protons initial pK. Variations on these minimum barriers are also considered. The important finding is that there are a number of reactions with rates greater than these minimum barriers would permit. This suggests a third mechanism lower in energy; the concerted PCET has been offered as this third mechanism. This assertion has also been supported by the observation of unusually large kinetic isotope effects (KIE).
A typical method for establishing PCET pathway is to show that the individual ET and PT pathways operate at higher activation energy than the concerted pathway. | 0 | Theoretical and Fundamental Chemistry |
γ-Amylase () (alternative names: Glucan 1,4-a-glucosidase; amyloglucosidase; exo-1,4-α-glucosidase; glucoamylase; lysosomal α-glucosidase; 1,4-α--glucan glucohydrolase) will cleave α(1–6) glycosidic linkages, as well as the last α-1,4 glycosidic bond at the nonreducing end of amylose and amylopectin, yielding glucose. The γ-amylase has the most acidic optimum pH of all amylases because it is most active around pH 3. They belong to a variety of different GH families, such as glycoside hydrolase family 15 in fungi, glycoside hydrolase family 31 of human MGAM, and glycoside hydrolase family 97 of bacterial forms. | 1 | Applied and Interdisciplinary Chemistry |
The only SI derived unit with a special name derived from the mole is the katal, defined as one mole per second of catalytic activity. Like other SI units, the mole can also be modified by adding a metric prefix that multiplies it by a power of 10:
One femtomole is exactly 602,214,076 molecules; attomole and smaller quantities cannot be exactly realized. The yoctomole, equal to around 0.6 of an individual molecule, did make appearances in scientific journals in the year the yocto- prefix was officially implemented. | 0 | Theoretical and Fundamental Chemistry |
A PFD can be computer generated from process simulators (see List of Chemical Process Simulators), CAD packages, or flow chart software using a library of chemical engineering symbols. Rules and symbols are available from standardization organizations such as DIN, ISO or ANSI. Often PFDs are produced on large sheets of paper.
PFDs of many commercial processes can be found in the literature, specifically in encyclopedias of chemical technology, although some might be outdated. To find recent ones, patent databases such as those available from the United States Patent and Trademark Office can be useful. | 1 | Applied and Interdisciplinary Chemistry |
TRIM28 has been shown to interact with:
* CBX5,
* CEBPB,
* Glucocorticoid receptor,
* SETDB1 and
* ZNF10. | 1 | Applied and Interdisciplinary Chemistry |
Cryosurgery is also used to treat internal and external tumors as well as tumors in the bone. To cure internal tumors, a hollow instrument called a cryoprobe is used, which is placed in contact with the tumor. Liquid nitrogen or argon gas is passed through the cryoprobe. Ultrasound or MRI is used to guide the cryoprobe and monitor the freezing of the cells. This helps in limiting damage to adjacent healthy tissues. A ball of ice crystals forms around the probe which results in freezing of nearby cells. When it is required to deliver gas to various parts of the tumor, more than one probe is used. After cryosurgery, the frozen tissue is either naturally absorbed by the body in the case of internal tumors, or it dissolves and forms a scab for external tumors. | 1 | Applied and Interdisciplinary Chemistry |
Percoll was previously used in assisted reproductive technology (ART) to select sperm from semen by density gradient centrifugation, for use in techniques such as in vitro fertilization or intrauterine insemination. However, in 1996, Pharmacia sent out a letter to laboratories stating that Percoll should be used for research purposes only, not clinical. Pharmacia had not marketed it as a sperm preparation product; it had been repackaged and sold as such by third-party manufacturers. The FDA Warning Letter was due to concerns that PVP might cause damage to sperm (an unknown issue), and also that some batches of Percoll contained high levels of endotoxin (a known issue). The latter concern also applies to the use of Percoll with any other cells that might be injected back into a patient, since endotoxin can cause severe inflammation and fever. Since then it has been replaced with other colloids in the ART industry. | 1 | Applied and Interdisciplinary Chemistry |
Mauveine is a mixture of four related aromatic compounds differing in number and placement of methyl groups. Its organic synthesis involves dissolving aniline, p-toluidine, and o-toluidine in sulfuric acid and water in a roughly 1:1:2 ratio, then adding potassium dichromate.
Mauveine A () incorporates 2 molecules of aniline, one of p-toluidine, and one of o-toluidine. Mauveine B () incorporates one molecule each of aniline, p-toluidine, and two of o-toluidine. In 1879, Perkin showed mauveine B related to safranines by oxidative/reductive loss of the p-tolyl group. In fact, safranine is a 2,8-dimethyl phenazinium salt, whereas the parasafranine produced by Perkin is presumed to be the 1,8- (or 2,9-) dimethyl isomer.
The molecular structure of mauveine proved difficult to determine, finally being identified in 1994. In 2007, two more were isolated and identified: mauveine B2, an isomer of mauveine B with methyl on different aryl group, and mauveine C, which has one more p-methyl group than mauveine A.
In 2008, additional mauveines and pseudomauveines were discovered, bringing the total number of these compounds up to 12. In 2015 a crystal structure was reported for the first time. | 0 | Theoretical and Fundamental Chemistry |
Bukele founded four mosques during his lifetime, including the first mosque in El Salvador in 1992. He served as imam of the Salvadoran Islamic Community and was part of the Islamic Organization for Latin America and the Caribbean. He was a founding member of the Council of Religions for Peace of El Salvador. | 1 | Applied and Interdisciplinary Chemistry |
A bonnet acts as a cover on the valve body. It is commonly semi-permanently screwed into the valve body or bolted onto it. During manufacture of the valve, the internal parts are put into the body and then the bonnet is attached to hold everything together inside. To access internal parts of a valve, a user would take off the bonnet, usually for maintenance. Many valves do not have bonnets; for example, plug valves usually do not have bonnets. Many ball valves do not have bonnets since the valve body is put together in a different style, such as being screwed together at the middle of the valve body. | 1 | Applied and Interdisciplinary Chemistry |
Explosive decomposition of organo nitro compounds are redox reactions, wherein both the oxidant (nitro group) and the fuel (hydrocarbon substituent) are bound within the same molecule. The explosion process generates heat by forming highly stable products including molecular nitrogen (N), carbon dioxide, and water. The explosive power of this redox reaction is enhanced because these stable products are gases at mild temperatures. Many contact explosives contain the nitro group. | 0 | Theoretical and Fundamental Chemistry |
Vanadates can behave as structural mimics of phosphates, and in this way they exhibit biological activity.
Ammonium metavanadate is used to prepare Mandelin reagent, a qualitative test for alkaloids. | 0 | Theoretical and Fundamental Chemistry |
In 1876, he became obsessed with Anna Ivanova Popova and began courting her; in 1881 he proposed to her and threatened suicide if she refused. His divorce from Leshcheva was finalized one month after he had married Popova (on 2 April) in early 1882. Even after the divorce, Mendeleev was technically a bigamist; the Russian Orthodox Church required at least seven years before lawful remarriage. His divorce and the surrounding controversy contributed to his failure to be admitted to the Russian Academy of Sciences (despite his international fame by that time). His daughter from his second marriage, Lyubov, became the wife of the famous Russian poet Alexander Blok. His other children were son Vladimir (a sailor, he took part in the notable Eastern journey of Nicholas II) and daughter Olga, from his first marriage to Feozva, and son Ivan and twins from Anna.
Though Mendeleev was widely honored by scientific organizations all over Europe, including (in 1882) the Davy Medal from the Royal Society of London (which later also awarded him the Copley Medal in 1905), he resigned from Saint Petersburg University on 17 August 1890. He was elected a Foreign Member of the Royal Society (ForMemRS) in 1892, and in 1893 he was appointed director of the Bureau of Weights and Measures, a post which he occupied until his death.
Mendeleev also investigated the composition of petroleum, and helped to found the first oil refinery in Russia. He recognized the importance of petroleum as a feedstock for petrochemicals. He is credited with a remark that burning petroleum as a fuel "would be akin to firing up a kitchen stove with bank notes".
In 1905, Mendeleev was elected a member of the Royal Swedish Academy of Sciences. The following year the Nobel Committee for Chemistry recommended to the Swedish Academy to award the Nobel Prize in Chemistry for 1906 to Mendeleev for his discovery of the periodic system. He was also elected an International Member of the American Philosophical Society. The Chemistry Section of the Swedish Academy supported this recommendation. The academy was then supposed to approve the committees choice, as it has done in almost every case. Unexpectedly, at the full meeting of the academy, a dissenting member of the Nobel Committee, Peter Klason, proposed the candidacy of Henri Moissan whom he favored. Svante Arrhenius, although not a member of the Nobel Committee for Chemistry, had a great deal of influence in the academy and also pressed for the rejection of Mendeleev, arguing that the periodic system was too old to acknowledge its discovery in 1906. According to the contemporaries, Arrhenius was motivated by the grudge he held against Mendeleev for his critique of Arrheniuss dissociation theory. After heated arguments, the majority of the academy chose Moissan by a margin of one vote. The attempts to nominate Mendeleev in 1907 were again frustrated by the absolute opposition of Arrhenius.
In 1907, Mendeleev died at the age of 72 in Saint Petersburg from influenza, just 6 days short of his 73rd birthday. His last words were to his physician: "Doctor, you have science, I have faith," which is possibly a Jules Verne quote. | 0 | Theoretical and Fundamental Chemistry |
In particle physics, spin polarization is the degree to which the spin, i.e., the intrinsic angular momentum of elementary particles, is aligned with a given direction. This property may pertain to the spin, hence to the magnetic moment, of conduction electrons in ferromagnetic metals, such as iron, giving rise to spin-polarized currents. It may refer to (static) spin waves, preferential correlation of spin orientation with ordered lattices (semiconductors or insulators).
It may also pertain to beams of particles, produced for particular aims, such as polarized neutron scattering or muon spin spectroscopy. Spin polarization of electrons or of nuclei, often called simply magnetization, is also produced by the application of a magnetic field. Curie law is used to produce an induction signal in electron spin resonance (ESR or EPR) and in nuclear magnetic resonance (NMR).
Spin polarization is also important for spintronics, a branch of electronics. Magnetic semiconductors are being researched as possible spintronic materials.
The spin of free electrons is measured either by a LEED image from a clean wolfram-crystal (SPLEED) or by an electron microscope composed purely of electrostatic lenses and a gold foil as a sample. Back scattered electrons are decelerated by annular optics and focused onto a ring shaped electron multiplier at about 15°. The position on the ring is recorded. This whole device is called a Mott-detector. Depending on their spin the electrons have the chance to hit the ring at different positions. 1% of the electrons are scattered in the foil. Of these 1% are collected by the detector and then about 30% of the electrons hit the detector at the wrong position. Both devices work due to spin orbit coupling.
The circular polarization of electromagnetic fields is due to spin polarization of their constituent photons.
In the most generic context, spin polarization is any alignment of the components of a non-scalar (vectorial, tensorial, spinor) field with its arguments, i.e., with the nonrelativistic three spatial or relativistic four spatiotemporal regions over which it is defined. In this sense, it also includes gravitational waves and any field theory that couples its constituents with the differential operators of vector analysis. | 0 | Theoretical and Fundamental Chemistry |
Cross ventilation works well in climates with hotter temperatures, where the system allows continual changes of the air within the building, refreshing it and reducing the temperature inside the structure and also when the window on the windward side of the building is not opened as much as the one on the leeward side. Cross ventilation will not be efficacious if the windows are more than 12m apart and if a window is behind a door that is regularly shut.
An opened window that faces a prevailing wind and is conjugated with another window on the opposite side of a building will supply natural ventilation for fresh air. A decent and effective cross ventilation will remove heat from the interior and keep indoor air temperatures approximately 1.5 °C (2.7°F) below the outdoor air temperatures, ensuring that there is a steady inflow and outflow of fresh air inside the building.
Besides windows, other openings like brise soleils, doors, louvers or ventilation grills and ducts can also work as effective ventilation openings, though an awning window provides the least effectivity. The wind surrounding building structures is important when it comes to assessing the air quality and thermal comfort indoors since both air and heat exchange rely heavily on the wind pressure on the exterior of the building. For the best airflow, the windward windows of the occupied space should not be opened as much as those on the leeward side. Disadvantages of wind-driven ventilation include capricious wind speeds and directions (which may create a strong unpleasant draft), and the polluted air from the outside that may tarnish the indoor air quality.
Cross ventilation is not recommended for use in disease prevention when air is being moved by the cross ventilation from an unclean area into a clean area. | 1 | Applied and Interdisciplinary Chemistry |
Cosmetic implants — often prosthetics — attempt to bring some portion of the body back to an acceptable aesthetic norm. They are used as a follow-up to mastectomy due to breast cancer, for correcting some forms of disfigurement, and modifying aspects of the body (as in buttock augmentation and chin augmentation). Examples include the breast implant, nose prosthesis, ocular prosthesis, and injectable filler. | 1 | Applied and Interdisciplinary Chemistry |
*PPID Peptidyl-prolyl cis-trans isomerase D
*PPIE Peptidyl-prolyl cis-trans isomerase E
*PPIF Peptidyl-prolyl cis-trans isomerase F
*PPIG Peptidyl-prolyl cis-trans isomerase G
*PPIH Cyclophilin H
*CANX Calnexin. Folding of glycoproteins within endoplasmic reticulum
*CAPN1 Calpain subunit
*CAPN7
*CAPNS1 Calpain protease subunit
*NACA Nascent polypeptide associated complex alpha polypeptide
*NACA2
*PFDN2 Prefoldin 2
*PFDN4 Prefoldin 4
*PFDN5 Prefoldin 5
*PFDN6 Prefoldin 6
*SNX2 Sorting nexin 2
*SNX3 Sorting nexin 3
*SNX4 Sorting nexin 4
*SNX5 Sorting nexin 5
*SNX6 Sorting nexin 6
*SNX9 Sorting nexin 9
*SNX12 Sorting nexin 12
*SNX13 Sorting nexin 13
*SNX17 Sorting nexin 17
*SNX18 Sorting nexin 18
*SNX19 Sorting nexin 19
*SNX25 Sorting nexin 25
*SSR1 Translocon-associated protein TRAPA. Protein translocation in ER
*SSR2 Translocon-associated protein TRAPB. Protein translocation in ER
*SSR3 Translocon-associated protein TRAPG. Protein translocation in ER
*SUMO1 Protein targeting
*SUMO3 Protein targeting | 1 | Applied and Interdisciplinary Chemistry |
The Human-transcriptome DataBase for Alternative Splicing (H-DBAS) is a database of alternatively spliced human transcripts based on H-Invitational. | 1 | Applied and Interdisciplinary Chemistry |
Because of sputtering occurring at the cathode, the colors emitted from regions near the cathode are quite different from the anode. Particles sputtered from the cathode are excited and emit radiation from the metals and oxides that make up the cathode. The radiation from these particles combines with radiation from excited carrier gas, giving the cathode region a white or blue color, while in the rest of the tube, radiation is only from the carrier gas and tends to be more monochromatic.
Electrons near the cathode are less energetic than the rest of the tube. Surrounding the cathode is a negative field, which slows electrons as they are ejected from the surface. Only those electrons with the highest velocity are able to escape this field, and those without enough kinetic energy are pulled back into the cathode. Once outside the negative field, the attraction from the positive field begins to accelerate these electrons toward the anode. During this acceleration electrons are deflected and slowed down by positive ions speeding toward the cathode, which, in turn, produces bright blue-white bremsstrahlung radiation in the negative glow region. | 0 | Theoretical and Fundamental Chemistry |
Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the negative logarithm (base 10) of the activity of hydronium ions ( or, more precisely, ) in a solution. In soils, it is measured in a slurry of soil mixed with water (or a salt solution, such as ), and normally falls between 3 and 10, with 7 being neutral. Acid soils have a pH below 7 and alkaline soils have a pH above 7. Ultra-acidic soils (pH < 3.5) and very strongly alkaline soils (pH > 9) are rare.
Soil pH is considered a master variable in soils as it affects many chemical processes. It specifically affects plant nutrient availability by controlling the chemical forms of the different nutrients and influencing the chemical reactions they undergo. The optimum pH range for most plants is between 5.5 and 7.5; however, many plants have adapted to thrive at pH values outside this range. | 0 | Theoretical and Fundamental Chemistry |
Magnesium is anodized primarily as a primer for paint. A thin (5 μm) film is sufficient for this. Thicker coatings of 25 μm and up can provide mild corrosion resistance when sealed with oil, wax, or sodium silicate. Standards for magnesium anodizing are given in AMS 2466, AMS 2478, AMS 2479, and ASTM B893. | 1 | Applied and Interdisciplinary Chemistry |
For certain classes of molecules, the general formula can be simplified or rewritten more clearly. For example:
where
:a = number of carbon atoms in the compound
:b = number of hydrogen atoms in the compound
:c = number of nitrogen atoms in the compound
:f = number of halogen atoms in the compound
or
where C = number of carbons, H = number of hydrogens, X = number of halogens and N = number of nitrogens, gives an equivalent result.
In either case, oxygen and other divalent atoms do not contribute to the degree of unsaturation, as 2 − 2 = 0. | 0 | Theoretical and Fundamental Chemistry |
16 October 1918 MHWC were converted into second Moscow State University. The first rector of the 2nd Moscow State University was appointed academician S. S. Nametkin who worked since 1913 as a head of the Department of Organic Chemistry of MHWC. As rector, he remained until 1924. As part of the 2nd Moscow State University became the chemical-pharmaceutical department, which in 1919 was transformed into the chemical and pharmaceutical department. At this time, on the faculty worked well-known Professors A. M. Berkengeim, B. K. Mlodzeevskii, S. S. Nametkin, M. I. Prozin, A. N. Reformatsky, O. N. Tsuberbiller. In 1929, the faculty became a chemical faculty of the university type with specialties such as:
* Chemical – pharmaceutical chemistry;
* Basic chemistry;
* Aniline chemistry;
* Chemistry of rare elements;
* Coke-benzene chemistry;
* Organic Synthesis.
Faculty graduates go to work in the factories, involve in the implementation of research projects that receive a wide scope. During 1922 – 1928 years it has been published about 300 papers and 11 monographs. The greatest successes are achieved in the fields of organic and pharmaceutical chemistry under the direction of heads of departments, academics S. S. Nametkin, B. M. Rodionov, Professor A. M. Berkengeim. Production of new drugs being introduced in the pharmaceutical factory belonging to faculty. | 1 | Applied and Interdisciplinary Chemistry |
PT has been shown to affect the innate immune response. It inhibits the early recruitment of neutrophils and macrophages, and interferes with early chemokine production and neutrophil chemotaxis. Chemokines are signalling molecules produced by infected cells and attract neutrophils and macrophages. Neutrophil chemotaxis is thought to be disrupted by inhibiting G-protein-coupled chemokine receptors by the ADP-ribosylation of G proteins.
Because of the disrupted signalling pathways, synthesis of chemokines will be affected. This will prevent the infected cell from producing them and thereby inhibiting recruitment of neutrophils. Under normal circumstances, alveolar macrophages and other lung cells produce a variety of chemokines. PT has been found to inhibit the early transcription of keratinocyte-derived chemokine, macrophage inflammatory protein 2 and LPS-induced CXC chemokine. Eventually, PT causes lymphocytosis, one of the systemic manifestations of whooping cough.
PT, a decisive virulence determinant of B. pertussis, is able to cross the blood–brain barrier by increasing its permeability. As a result, PT can cause severe neurological complications; however, recently it has been found that the medicinal usage of Pertussis toxin can promote the development of regulatory T cells and prevent central nervous system autoimmune disease, such as multiple sclerosis. | 1 | Applied and Interdisciplinary Chemistry |
A crystalline solid has been traditionally viewed as a static entity where the movements of its atomic components are limited to its vibrational equilibrium. As seen by the transformation of graphite to diamond, solid to solid transformation can occur under physical or chemical pressure. It has been proposed that the transformation from one crystal arrangement to another occurs in a cooperative manner. Most of these studies have been focused in studying an organic or metal-organic framework. In addition to studies of macromolecular crystalline transformation, there are also studies of single-crystal molecules that can change their conformation in the presence of organic solvents. An organometallic complex has been shown to morph into various orientations depending on whether it is exposed to solvent vapors or not. | 0 | Theoretical and Fundamental Chemistry |
Newton's various surviving alchemical notebooks clearly show that he made no distinctions between alchemy and what we today consider science. Optics experiments were written on the same pages as recipes from arcane sources. Newton did not always record his chemical experiments in the most transparent way. Alchemists were notorious for veiling their writings in impenetrable jargon; Newton himself invented new symbols and systems. | 1 | Applied and Interdisciplinary Chemistry |
Malonyl-CoA is formed in the first step of mitochondrial fatty acid synthesis (mtFASII) from malonic acid by malonyl-CoA synthetase (ACSF3). | 1 | Applied and Interdisciplinary Chemistry |
The Cantons of Switzerland perform tests to assess the presence of genetically modified organisms in foodstuffs. In 2008, 3% of the tested samples contained detectable amounts of GMOs. In 2012, 12% of the samples analysed contained detectable amounts of GMOs (including 2.4% of GMOs forbidden in Switzerland). Except one, all the samples tested contained less than 0.9% of GMOs; which is the threshold that impose labelling indicating the presence of GMOs. | 1 | Applied and Interdisciplinary Chemistry |
Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Chemically, the precious metals tend to be less reactive than most elements. They include gold and silver, but also the so-called platinum group metals: ruthenium, rhodium, palladium, osmium, iridium, and platinum (see precious metals). Extraction of these metals from their corresponding hosting minerals would typically require pyrometallurgy (e.g., roasting), hydrometallurgy (cyanidation), or both as processing routes.
Early studies have demonstrated that gold dissolution rate in Ethaline compares very favourably to the cyanidation method, which is further enhanced by the addition of iodine as an oxidising agent. In an industrial process the iodine has the potential to be employed as an electrocatalyst, whereby it is continuously recovered in situ from the reduced iodide by electrochemical oxidation at the anode of an electrochemical cell. Dissolved metals can be selectively deposited at the cathode by adjusting the electrode potential. The method also allows better selectivity as part of the gangue (e.g., pyrite) tend to be dissolved more slowly.
Sperrylite (PtAs) and moncheite (PtTe), which are typically the more abundant platinum minerals in many orthomagmatic deposits, do not react under the same conditions in Ethaline because they are disulphide (pyrite), diarsenide (sperrylite) or ditellurides (calaverite and moncheite) minerals, which are particularly resistant to iodine oxidation. The reaction mechanism by which dissolution of platinum minerals is taking place is still under investigation. | 1 | Applied and Interdisciplinary Chemistry |
As the temperature in the joint increases, polymer begins to melt and a fusion zone is formed. The molten polymer in the fusion zone exerts an outward force on the surrounding solid polymer material, referred to as "cold zones". These cold zones cause a pressure to develop in the molten fusion zone. The pressure in the fusion zone takes some time to reach its maximum value, usually not reaching the peak until about a quarter of the way into the joining process. After the current is shut off and cooling begins, the pressure slowly decreases until the joint is uniform temperature. | 0 | Theoretical and Fundamental Chemistry |
Acetic anhydride is produced by carbonylation of methyl acetate in a process that is similar to the Monsanto acetic acid synthesis. Methyl acetate is used in place of methanol as a source of methyl iodide.
: CHCOCH + CO → (CHCO)O
In this process lithium iodide converts methyl acetate to lithium acetate and methyl iodide, which in turn affords, through carbonylation, acetyl iodide. Acetyl iodide reacts with acetate salts or acetic acid to give the anhydride. Rhodium iodides and lithium salts are employed as catalysts. Because acetic anhydride hydrolyzes, the conversion is conducted under anhydrous conditions in contrast to the Monsanto acetic acid synthesis. | 0 | Theoretical and Fundamental Chemistry |
Atmospheric carbon dioxide has risen from 280 to 409 ppm since the industrial revolution. This increase in carbon dioxide has led to a 0.1 decrease in pH, and it could decrease by 0.5 by 2100. When carbon dioxide meets seawater, it forms carbonic acid; the molecules dissociate into hydrogen, bicarbonate, and carbonate, and they lower the pH of the ocean. Sea surface temperature, ocean acidity, and dissolved inorganic carbon are also positively correlated with atmospheric carbon dioxide. Ocean acidification can cause hypercapnia and increase stress in marine organisms, thereby leading to decreased biodiversity. Coral reefs themselves can also be negatively affected by ocean acidification, as calcification rates decrease and acidity increases.
Aragonite is impacted by the process of ocean acidification because it is a form of calcium carbonate. It is essential in coral viability and health because it is found in coral skeletons and is more readily soluble than calcite. Increasing carbon dioxide levels can reduce coral growth rates from 9 to 56% due to the lack of available carbonate ions needed for the calcification process.Other calcifying organisms, such as bivalves and gastropods, experience negative effects due to ocean acidification as well. The excess hydrogen ions in the acidic water dissolve their shells, limiting their shelter and reproduction rates.
As a biodiversity hotspot, the many taxa of the Great Barrier Reef are threatened by ocean acidification. Rare and endemic species are in greater danger due to ocean acidification, because they rely upon the Great Barrier Reef more extensively. Additionally, the risk of coral reefs collapsing due to acidification poses a threat to biodiversity. The stress of ocean acidification could also negatively affect other biological processes, such as reducing photosynthesis or reproduction and allowing organisms to become vulnerable to disease. | 0 | Theoretical and Fundamental Chemistry |
As long ago as 1890, Hiorns observed as follows:
:"Noble Metals. Gold, Platinum, Silver, and a few rare metals. The members of this class have little or no tendency to unite with oxygen in the free state, and when placed in water at a red heat do not alter its composition. The oxides are readily decomposed by heat in consequence of the feeble affinity between the metal and oxygen."
Smith, writing in 1946, continued the theme:
:"There is no sharp dividing line [between noble metals and base metals] but perhaps the best definition of a noble metal is a metal whose oxide is easily decomposed at a temperature below a red heat."
:"It follows from this that noble metals...have little attraction for oxygen and are consequently not oxidised or discoloured at moderate temperatures."
Such nobility is mainly associated with the relatively high electronegativity values of the noble metals, resulting in only weakly polar covalent bonding with oxygen. The table lists the melting points of the oxides of the noble metals, and for some of those of the non-noble metals, for the elements in their most stable oxidation states. | 1 | Applied and Interdisciplinary Chemistry |
Triparental mating is a form of bacterial conjugation where a conjugative plasmid present in one bacterial strain assists the transfer of a mobilizable plasmid present in a second bacterial strain into a third bacterial strain. Plasmids are introduced into bacteria for such purposes as transformation, cloning, or transposon mutagenesis. Triparental matings can help overcome some of the barriers to efficient plasmid mobilization. For instance, if the conjugative plasmid and the mobilizable plasmid are members of the same incompatibility group they do not need to stably coexist in the second bacterial strain for the mobilizable plasmid to be transferred. | 1 | Applied and Interdisciplinary Chemistry |
Fluid inclusions trapped in veins and minerals have been used as a proxy to explore the deformation history in orogenic belts. As fluid activities are considerably more in shear zones in an orogenic belt, the fluid inclusions in a shear zone have been also used to explore the seismic activities during the evolution of the shear zone. In orogenic belts the earthquakes sometimes attributed to be linked with fluid activity at depth. Indirect geophysical evidence points out the role of fluid in earthquakes in many shear zones, however a few studies provide geological evidence for the role of fluid in earthquakes. | 0 | Theoretical and Fundamental Chemistry |
With the advent of the high-throughput DNA and RNA sequence identification methods (such as Illumina sequencing), it became possible to efficiently analyse nucleotide sequences of large numbers of relatively short DNA and RNA fragments. Sequences of these fragments can be superimposed to reconstruct the source. Alternatively, if the source sequence is already known, the fragments can be found within it (“mapped”), and their individual numbers counted. Thus, if an initial stage exists whereby the fragments are differentially present or selected (“enriched”), this approach can be used to quantitatively describe such stage over even a very large number or length of the input sequences, most usually encompassing the entire DNA or RNA of the cell.
TCP-seq is based on these capabilities of the high-throughput RNA sequencing and further uses the nucleic acid protection phenomenon. The protection is manifested as resistance to depolymerisation or modification of stretches of nucleic acids (particularly, RNA) that are tightly bound to or engulfed with other biomolecules, which thus leave their “footprints” over the nucleic acid strand. These “footprint” fragments therefore represent location on nucleic acid chain where the interaction occurs. By sequencing and mapping the fragments back to the source sequence, it is possible to precisely identify the locations and counts of these intermolecular contacts.
In case of TCP-seq, ribosomes and ribosomal subunits engaged in interaction with mRNA are first fast chemically crosslinked to it with formaldehyde to preserve existing state of interactions (“snapshot” of distribution) and to block any possible non-equilibrium processes. The crosslinking can be performed directly in, but not restricted to, live cells. The RNA is then partially degraded (e.g. with ribonuclease) so that only fragments protected by the ribosomes or ribosomal subunits are left. The protected fragments are then purified according to the sedimentation dynamics of the attached ribosomes or ribosomal subunits, de-blocked, sequenced and mapped to the source transcriptome, giving the original locations of the translation complexes over mRNA.
TCP-seq merges several elements typical to other transcriptome-wide analyses of its kind. In particular, polysome profiling and ribosome (translation) profiling approaches are also employed to identify mRNA involved in polysome formation and locations of elongating ribosomes over coding regions of transcripts, correspondingly. These methods, however, do not use chemical stabilisation of translation complexes and purification of the covalently bound intermediates from the live cells. TCP-seq thus can be considered more as a functional equivalent of ChIP-seq and similar methods of investigating momentary interactions of DNA that are redesigned to be applicable for translation. | 1 | Applied and Interdisciplinary Chemistry |
The World Ocean Atlas (WOA) is a data product of the Ocean Climate Laboratory of the National Oceanographic Data Center (U.S.). The WOA consists of a climatology of fields of in situ ocean properties for the World Ocean. It was first produced in 1994 (based on the earlier Climatological Atlas of the World Ocean, 1982), with later editions at roughly four year intervals in 1998, 2001, 2005, 2009, 2013, 2018, and 2023. | 0 | Theoretical and Fundamental Chemistry |
There are various methods of introducing foreign DNA into a eukaryotic cell: some rely on physical treatment (electroporation, cell squeezing, nanoparticles, magnetofection); others rely on chemical materials or biological particles (viruses) that are used as carriers. There are many different methods of gene delivery developed for various types of cells and tissues, from bacterial to mammalian. Generally, the methods can be divided into three categories: physical, chemical, and biological.
Physical methods include electroporation, microinjection, gene gun, impalefection, hydrostatic pressure, continuous infusion, and sonication. Chemicals include methods such as lipofection, which is a lipid-mediated DNA-transfection process utilizing liposome vectors. It can also include the use of polymeric gene carriers (polyplexes). Biological transfection is typically mediated by viruses, utilizing the ability of a virus to inject its DNA inside a host cell. A gene that is intended for delivery is packaged into a replication-deficient viral particle. Viruses used to date include retrovirus, lentivirus, adenovirus, adeno-associated virus, and herpes simplex virus. | 1 | Applied and Interdisciplinary Chemistry |
The range and degree of human health effects seems to vary annually and temporally in coastal regions, depending on the red tide density as well as variation in toxicity differences among dinoflagellate strains and their subsequent consumers. The Gulf of Mexico, and in particular the west coast of Florida, is the most heavily impacted by the adverse health and environmental effects of nearly annual K. brevis blooms. This region has suffered significant economic losses in local communities that rely on tourism and recreational fishing along with bad publicity over the years. Shellfish poisonings have been known about in Florida since the 1880s, although the cause was not identified as K. brevis until 1960.
The fishing industry loses around 18 million dollars annually due to brevetoxin exposure and the resulting fish kills. Also, around one million dollars has been spent annually on public health due to shellfish poisoning from 1987 to 1992. A major obstacle for these industries and public health is inability to contain a bloom, and it is undetectable in taste and smell, only chemically. One major concern for exposure is not just illness, but that brevetoxin can alter human DNA in lymphocytes, impacting immune function.
The metabolism of brevetoxins in shellfish is particularly concerning, as certain derivatives have been shown to remain in the animal over extended periods of time. It has been shown that the main toxin produced by K. brevis, PbTx-2, is rapidly metabolized, resulting in the production of metabolites that endure in the animal's system for a significantly longer period of time. This stands in contrast to PbTx-3, which is typically eliminated from the shellfish in more or less its original form within a few weeks.
Brevetoxin concentrations in seafood and the regulation of toxic substance monitoring in the animals is concerning. In Florida, only oysters and clams are monitored for NSP. Scallops are not monitored, although scallop-related NSP does not normally occur because in most cases, the muscle which does not accumulate brevetoxin to dangerous levels is consumed. Additionally, scallops are less tolerant to brevetoxins as compared to other bivalves and die off quickly after exposure to K. brevis red tides. However, smaller bivalves such as chione clams and coquinas can accumulate extremely high levels of brevetoxins and are not monitored, which could potentially impact both human and wildlife health in negative ways. According to evidence from Poli et al., whelks are implicated in an NSP event in 1996.
With respect to ichthyotoxicity, reports of massive fish kills have been reported in the Gulf of Mexico as far back as 1844. Originally, fish bioassay-guided fractionation was used to isolate the toxins, but accumulation in or food-web transfer by fish has not been regarded as a threat. Steidinger hypothesized that the presence of brevetoxin found in dolphin mortalities and prey mortalities in 1987-1988 were in part due to brevetoxin transfer through fish. While dangerous levels of brevetoxins have not been found in the muscles of live fish to date, the internal organs of fish are highly susceptible to dangerous levels of toxicity and should not be eaten. It is conjectured that chronic low-level exposure to brevetoxin metabolites can occur through shellfish and fish, although the effects of this have not been studied in detail and remain largely unknown. | 0 | Theoretical and Fundamental Chemistry |
* Computational analysis tools such as t-test, hierarchical clustering, self-organizing maps, regulatory network reconstruction, BLAST searches, pattern-motif discovery, protein structure prediction, structure-based protein annotation, etc.
* Visualization of gene expression (heatmaps, volcano plot), molecular interaction networks (through Cytoscape), protein sequence and protein structure data (e.g., MarkUs).
* Integration of gene and pathway annotation information from curated sources as well as through Gene Ontology enrichment analysis.
* Component integration through platform management of inputs and outputs. Among data that can be shared between components are expression datasets, interaction networks, sample and marker (gene) sets and sequences.
* Dataset history tracking - complete record of data sets used and input settings.
* Integration with 3rd party tools such as Genepattern, Cytoscape, and Genomespace.
Demonstrations of each feature described can be found at[http://wiki.c2b2.columbia.edu/workbench/index.php/Tutorials GeWorkbench-web Tutorials]. | 1 | Applied and Interdisciplinary Chemistry |
Meanwhile, the oxygen atom has lone pairs of nonbonded electrons that render it weakly basic in the presence of strong acids such as sulfuric acid. For example, with methanol:
Upon treatment with strong acids, alcohols undergo the E1 elimination reaction to produce alkenes. The reaction, in general, obeys Zaitsev's Rule, which states that the most stable (usually the most substituted) alkene is formed. Tertiary alcohols are eliminated easily at just above room temperature, but primary alcohols require a higher temperature.
This is a diagram of acid catalyzed dehydration of ethanol to produce ethylene:
A more controlled elimination reaction requires the formation of the xanthate ester. | 0 | Theoretical and Fundamental Chemistry |
Given the genetic makeup of an organism, the complete set of possible reactions constitutes its reactome. Reactome, located at http://www.reactome.org is a curated, peer-reviewed resource of human biological processes/pathway data. The basic unit of the Reactome database is a reaction; reactions are then grouped into causal chains to form pathways The Reactome data model allows us to represent many diverse processes in the human system, including the pathways of intermediary metabolism, regulatory pathways, and signal transduction, and high-level processes, such as the cell cycle. Reactome provides a qualitative framework, on which quantitative data can be superimposed. Tools have been developed to facilitate custom data entry and annotation by expert biologists, and to allow visualization and exploration of the finished dataset as an interactive process map. Although the primary curational domain is pathways from Homo sapiens, electronic projections of human pathways onto other organisms are regularly created via putative orthologs, thus making Reactome relevant to model organism research communities. The database is publicly available under open source terms, which allows both its content and its software infrastructure to be freely used and redistributed. Studying whole transcriptional profiles and cataloging protein–protein interactions has yielded much valuable biological information, from the genome or proteome to the physiology of an organism, an organ, a tissue or even a single cell. The Reactome database containing a framework of possible reactions which, when combined with expression and enzyme kinetic data, provides the infrastructure for quantitative models, therefore, an integrated view of biological processes, which links such gene products and can be systematically mined by using bioinformatics applications. Reactome data available in a variety of standard formats, including BioPAX, SBML and PSI-MI, and also enable data exchange with other pathway databases, such as the Cycs, KEGG and amaze, and molecular interaction databases, such as BIND and HPRD. The next data release will cover apoptosis, including the death receptor signaling pathways, and the Bcl2 pathways, as well as pathways involved in hemostasis. Other topics currently under development include several signaling pathways, mitosis, visual phototransduction and hematopoeisis. In summary, Reactome provides high-quality curated summaries of fundamental biological processes in humans in a form of biologist-friendly visualization of pathways data, and is an open-source project. | 0 | Theoretical and Fundamental Chemistry |
The neutral molecule can be formed in a low pressure gas discharge tube.
A neutral beam of H can be formed from a beam of ions passing through gaseous potassium, which donates an electron to the ion, forming K. Other gaseous alkali metals, such as caesium, can also be used to donate electrons. ions can be made in a duoplasmatron where an electric discharge passed through low pressure molecular hydrogen. This causes some H to become . Then H + + H. The reaction is exothermic with an energy of 1.7 eV, so the ions produced are hot with much vibrational energy. These can cool down via collisions with cooler gas if the pressure is high enough. This is significant because strongly vibrating ions produce strongly vibrating neutral molecules when neutralised according to the Franck–Condon principle. | 0 | Theoretical and Fundamental Chemistry |
Fe–Ni metal clusters are crucial for energy production in many bacteria. A primary source of energy in bacteria is the oxidation and reduction of H which is performed by hydrogenase enzymes.
These enzymes are able to create a charge gradient across the cell membrane which serves as an energy store. In aerobic environments, the oxidation and reduction of oxygen is the primary energy source. However, many bacteria are capable of living in environments where O supply is limited and use H as their primary energy source . The hydrogense enzymes which provide energy to the bacteria are centered around either a Fe–Fe or Fe–Ni active site. H metabolism is not used by humans or other complex life forms, but proteins in the mitochondria of mammalian life appear to have evolved from hydrogenase enzymes, indicating that hydrogenase is a crucial step in the evolutionary development of metabolism.
The active site of Fe–Ni containing hydrogenase enzymes often is composed of one or more bridging sulfur ligands, carbonyl, cyanide and terminal sulfur ligands. The non-bridging sulfur ligands are often cystine amino acid residues that attach the active site to the protein backbone. Metal–metal bonds between the Fe and Ni have not been observed. Several oxidation states of the Fe–Ni core have been observed in a variety of enzymes, though not all appear to be catalytically relevant.
The extreme oxygen and carbon monoxide sensitivity of these enzymes presents a challenge when studying the enzymes, but many crystallographic studies have been performed. Crystal structures for enzymes isolated from D. gigas, Desulfovibrio vulgaris, Desulfovibrio fructosovorans, Desulfovibrio desulfuricans, and Desulfomicrobium baculatum have been obtained, among others. A few bacteria, such as R. eutropha, have adapted to survive under ambient oxygen levels.
These enzymes have inspired study of structural and functional model complexes in hopes of making synthetic catalysis for hydrogen production (see Fe–Ni and hydrogen production, below, for more detail). | 0 | Theoretical and Fundamental Chemistry |
The radioactive decay modes of electron capture and internal conversion are known to be slightly sensitive to chemical and environmental effects that change the electronic structure of the atom, which in turn affects the presence of 1s and 2s electrons that participate in the decay process. A small number of nuclides are affected. For example, chemical bonds can affect the rate of electron capture to a small degree (in general, less than 1%) depending on the proximity of electrons to the nucleus. In Be, a difference of 0.9% has been observed between half-lives in metallic and insulating environments. This relatively large effect is because beryllium is a small atom whose valence electrons are in 2s atomic orbitals, which are subject to electron capture in Be because (like all s atomic orbitals in all atoms) they naturally penetrate into the nucleus.
In 1992, Jung et al. of the Darmstadt Heavy-Ion Research group observed an accelerated β decay of Dy. Although neutral Dy is a stable isotope, the fully ionized Dy undergoes β decay into the K and L shells to Ho with a half-life of 47 days.
Rhenium-187 is another spectacular example. Re normally undergoes beta decay to Os with a half-life of 41.6 × 10 years, but studies using fully ionised Re atoms (bare nuclei) have found that this can decrease to only 32.9 years. This is attributed to "bound-state β decay" of the fully ionised atom – the electron is emitted into the "K-shell" (1s atomic orbital), which cannot occur for neutral atoms in which all low-lying bound states are occupied.
A number of experiments have found that decay rates of other modes of artificial and naturally occurring radioisotopes are, to a high degree of precision, unaffected by external conditions such as temperature, pressure, the chemical environment, and electric, magnetic, or gravitational fields. Comparison of laboratory experiments over the last century, studies of the Oklo natural nuclear reactor (which exemplified the effects of thermal neutrons on nuclear decay), and astrophysical observations of the luminosity decays of distant supernovae (which occurred far away so the light has taken a great deal of time to reach us), for example, strongly indicate that unperturbed decay rates have been constant (at least to within the limitations of small experimental errors) as a function of time as well.
Recent results suggest the possibility that decay rates might have a weak dependence on environmental factors. It has been suggested that measurements of decay rates of silicon-32, manganese-54, and radium-226 exhibit small seasonal variations (of the order of 0.1%). However, such measurements are highly susceptible to systematic errors, and a subsequent paper has found no evidence for such correlations in seven other isotopes (Na, Ti, Ag, Sn, Ba, Am, Pu), and sets upper limits on the size of any such effects. The decay of radon-222 was once reported to exhibit large 4% peak-to-peak seasonal variations (see plot), which were proposed to be related to either solar flare activity or the distance from the Sun, but detailed analysis of the experiment's design flaws, along with comparisons to other, much more stringent and systematically controlled, experiments refute this claim. | 0 | Theoretical and Fundamental Chemistry |
Source: [https://www.science.org.au/opportunities-scientists/recognition/honorific-awards/career-awards/macfarlane-burnet-medal-and Australian Academy of Science] | 1 | Applied and Interdisciplinary Chemistry |
Michael Ramsey attended Bowling Green State University for his undergraduate studies where he obtained his Bachelor of Science in Chemistry with dual minors in Physics and Mathematics in June 1974.
He then went on to obtain his Doctor of Philosophy in Analytical chemistry from Indiana University Bloomington in January 1979. Dr. Ramsey conducted his research under the direction of Gary M. Hieftje from 1974-1979 culminating in his published dissertation "New Approaches for the Measurement of Subnanosecond Chemical Phenomena" [https://inis.iaea.org/search/searchsinglerecord.aspx?recordsFor=SingleRecord&RN=11540509]. | 0 | Theoretical and Fundamental Chemistry |
Two ways the release of volatile organic compounds (VOCs) may benefit plants are the deterrence of herbivores and the attraction of natural enemies. Synthetic products could replicate the distinct VOC profiles released by different plants; these products could be applied to plants suffering from pests that are targeted by the attracted natural enemy. This could cause natural enemies to enter crops that are occupied by pest populations that would otherwise likely remain undetected by the natural enemies.
The four elements that must be considered before manipulating VOCs are as follows: The VOCs must effectively aid the natural enemy in finding the prey; the pest must have natural enemies present; the fitness cost of potentially attracting more herbivores must be exceeded by attracting natural enemies; and the natural enemies must not be negatively affected by direct plant defenses that may be present. | 1 | Applied and Interdisciplinary Chemistry |
Various cellular reactions to ultrasound indicate the mechanism of molecular uptake via endocytosis. These observed reactionary phenomena include ion exchange, hydrogen peroxide, and cell intracellular calcium concentration. Studies have used patch clamping techniques to monitor membrane potential ion exchange for the role of endocytosis in sonoporation. Ultrasound application to cells and adjacent microbubbles was shown to produce marked cell membrane hyperpolarization along with progressive intracellular calcium increase, which is believed to be a consequence of calcium channels opening in response to microbubble oscillations. These findings act as support for ultrasound application inducing calcium-mediated uncoating of clathrin-coated pits seen in traditional endocytosis pathways. Other work reported sonoporation induced the formation of hydrogen peroxide, a cellular reaction that is also known to be involved with endocytosis. | 1 | Applied and Interdisciplinary Chemistry |
Continuous reactors are typically tube-like and manufactured from non-reactive materials such as stainless steel, glass, and polymers. Mixing methods include diffusion alone (if the diameter of the reactor is small e.g. <1 mm, such as in microreactors) and static mixers. Continuous flow reactors allow good control over reaction conditions including heat transfer, time, and mixing.
The residence time of the reagents in the reactor (i.e. the amount of time that the reaction is heated or cooled) is calculated from the volume of the reactor and the flow rate through it:
Therefore, to achieve a longer residence time, reagents can be pumped more slowly and/or a larger volume reactor used. Production rates can vary from nanoliters to liters per minute.
Some examples of flow reactors are spinning disk reactors; spinning tube reactors; multi-cell flow reactors; oscillatory flow reactors; microreactors; hex reactors; and aspirator reactors.
In an aspirator reactor a pump propels one reagent, which causes a reactant to be sucked in. This type of reactor was patented around 1941 by the Nobel company for the production of nitroglycerin. | 1 | Applied and Interdisciplinary Chemistry |
For a chemical reaction , the rate equation or rate law is a mathematical expression used in chemical kinetics to link the rate of a reaction to the concentration of each reactant. For a closed system at constant volume, this is often of the form
For reactions that go to completion (which implies very small ), or if only the initial rate is analyzed (with initial vanishing product concentrations), this simplifies to the commonly quoted form
For gas phase reaction the rate equation is often alternatively expressed in terms of partial pressures.
In these equations is the reaction rate coefficient or rate constant, although it is not really a constant, because it includes all the parameters that affect reaction rate, except for time and concentration. Of all the parameters influencing reaction rates, temperature is normally the most important one and is accounted for by the Arrhenius equation.
The exponents and are called reaction orders and depend on the reaction mechanism. For an elementary (single-step) reaction, the order with respect to each reactant is equal to its stoichiometric coefficient. For complex (multistep) reactions, however, this is often not true and the rate equation is determined by the detailed mechanism, as illustrated below for the reaction of H and NO.
For elementary reactions or reaction steps, the order and stoichiometric coefficient are both equal to the molecularity or number of molecules participating. For a unimolecular reaction or step, the rate is proportional to the concentration of molecules of reactant, so the rate law is first order. For a bimolecular reaction or step, the number of collisions is proportional to the product of the two reactant concentrations, or second order. A termolecular step is predicted to be third order, but also very slow as simultaneous collisions of three molecules are rare.
By using the mass balance for the system in which the reaction occurs, an expression for the rate of change in concentration can be derived. For a closed system with constant volume, such an expression can look like | 0 | Theoretical and Fundamental Chemistry |
For a pure wave motion in fluid dynamics, the Stokes drift velocity is the average velocity when following a specific fluid parcel as it travels with the fluid flow. For instance, a particle floating at the free surface of water waves, experiences a net Stokes drift velocity in the direction of wave propagation.
More generally, the Stokes drift velocity is the difference between the average Lagrangian flow velocity of a fluid parcel, and the average Eulerian flow velocity of the fluid at a fixed position. This nonlinear phenomenon is named after George Gabriel Stokes, who derived expressions for this drift in his 1847 study of water waves.
The Stokes drift is the difference in end positions, after a predefined amount of time (usually one wave period), as derived from a description in the Lagrangian and Eulerian coordinates. The end position in the Lagrangian description is obtained by following a specific fluid parcel during the time interval. The corresponding end position in the Eulerian description is obtained by integrating the flow velocity at a fixed position—equal to the initial position in the Lagrangian description—during the same time interval.
The Stokes drift velocity equals the Stokes drift divided by the considered time interval.
Often, the Stokes drift velocity is loosely referred to as Stokes drift.
Stokes drift may occur in all instances of oscillatory flow which are inhomogeneous in space. For instance in water waves, tides and atmospheric waves.
In the Lagrangian description, fluid parcels may drift far from their initial positions. As a result, the unambiguous definition of an average Lagrangian velocity and Stokes drift velocity, which can be attributed to a certain fixed position, is by no means a trivial task. However, such an unambiguous description is provided by the Generalized Lagrangian Mean (GLM) theory of Andrews and McIntyre in 1978.
The Stokes drift is important for the mass transfer of various kinds of material and organisms by oscillatory flows. It plays a crucial role in the generation of Langmuir circulations.
For nonlinear and periodic water waves, accurate results on the Stokes drift have been computed and tabulated. | 1 | Applied and Interdisciplinary Chemistry |
CK1ε and CK1δ are essential in the genetic transcription-translation (and post-translation) feedback loops that generate circadian rhythm in mammals.
The previously-characterized CK1ε isoform was first implicated as a clock gene when its Drosophila homolog, double-time (Doubletime (gene)), was discovered in 1998. Double-time is 86% identical to human CK1ε. Kloss et al and Price et al showed that mutations in double-time altered circadian rhythm. They found two DBT mutants that had abnormal free-running periods and one that was pupal-lethal but resulted in accumulations of hypophosphorylated PER protein. Since then, double-time's protein product DBT has been well characterized for its role in phosphorylating PER, the protein product of clock gene period in Drosophila, and its mammalian homologs appear to play a similar role.
In 2021, scientists reported the development of a light-responsive days-lasting modulator of circadian rhythms of tissues via Ck1 inhibition. Such modulators may be useful for chronobiology research and repair of organs that are "out of sync". | 1 | Applied and Interdisciplinary Chemistry |
Sara Rietti (Buenos Aires, 3 December 1930 – Buenos Aires, 28 May 2017), also known as Sara Bartfeld de Rietti, was the first nuclear chemist from Argentina. She was Chief of Staff of the Ministry of Science and Technology during the government of President Raúl Alfonsín. | 0 | Theoretical and Fundamental Chemistry |
Kenneth H. Cooper conducted a study for the United States Air Force in the late 1960s. One of the results of this was the Cooper test in which the distance covered running in 12 minutes is measured. Based on the measured distance, an estimate of V̇O max [in mL/(kg·min)] can be calculated by inverting the linear regression equation, giving us:
where d is the distance (in metres) covered in 12 minutes.
An alternative equation is:
where d′ is distance (in miles) covered in 12 minutes. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, a cycloalkene or cycloolefin is a type of alkene hydrocarbon which contains a closed ring of carbon atoms and either one or more double bonds, but has no aromatic character. Some cycloalkenes, such as cyclobutene and cyclopentene, can be used as monomers to produce polymer chains. Due to geometrical considerations, smaller cycloalkenes are almost always the cis isomers, and the term cis tends to be omitted from the names. Cycloalkenes require considerable p-orbital overlap in the form of a bridge between the carbon-carbon double bond; however, this is not feasible in smaller molecules due to the increase of strain that could break the molecule apart. In greater carbon number cycloalkenes, the addition of substituents decreases strain. trans-Cycloalkenes with 7 or fewer carbons in the ring will not occur under normal conditions because of the large amount of ring strain needed. In larger rings (8 or more atoms), cis–trans isomerism of the double bond may occur. This stability pattern forms part of the origin of Bredts rule, the observation that alkenes do not form at the bridgehead of many types of bridged ring systems because the alkene would necessarily be trans' in one of the rings. | 0 | Theoretical and Fundamental Chemistry |
NMMO monohydrate is used as a solvent in the lyocell process to produce lyocell fiber. It dissolves cellulose to form a solution called dope, and the cellulose is reprecipitated in a water bath to produce a fiber. The process is similar but not analogous to the viscose process. In the viscose process, cellulose is made soluble by conversion to its xanthate derivatives. With NMMO, cellulose is not derivatized but dissolves to give a homogeneous polymer solution. The resulting fiber is similar to viscose; this was observed, for example, for Valonia cellulose microfibrils. Dilution with water causes the cellulose to reprecipitate, i.e. the solvation of cellulose with NMMO is a water sensitive process.
Cellulose remains insoluble in most solvents because it has a strong and highly structured intermolecular hydrogen bonding network, which resists common solvents. NMMO breaks the hydrogen bonding network that keeps cellulose insoluble in water and other solvents. Similar solubility has been obtained in a few solvents, particularly a mix of lithium chloride in dimethyl acetamide and some hydrophilic ionic liquids. | 0 | Theoretical and Fundamental Chemistry |
Since the invention of agriculture, humans have directly and gradually influenced the carbon cycle over century-long timescales by modifying the mixture of vegetation in the terrestrial biosphere. Over the past several centuries, direct and indirect human-caused land use and land cover change (LUCC) has led to the loss of biodiversity, which lowers ecosystems' resilience to environmental stresses and decreases their ability to remove carbon from the atmosphere. More directly, it often leads to the release of carbon from terrestrial ecosystems into the atmosphere.
Deforestation for agricultural purposes removes forests, which hold large amounts of carbon, and replaces them, generally with agricultural or urban areas. Both of these replacement land cover types store comparatively small amounts of carbon so that the net result of the transition is that more carbon stays in the atmosphere. However, the effects on the atmosphere and overall carbon cycle can be intentionally and/or naturally reversed with reforestation. | 0 | Theoretical and Fundamental Chemistry |
Lipofuscin quantification is used for age determination in various crustaceans such as lobsters and spiny lobsters. Since these animals lack bony parts, they cannot be aged in the same way as bony fish, in which annual increments in the ear-bones or otoliths are commonly used. Age determination of fish and shellfish is a fundamental step in generating basic biological data such as growth curves, and is needed for many stock assessment methods. Several studies have indicated that quantifying the amount of lipofuscin present in the eye-stalks of various crustaceans can give an index of their age. This method has not yet been widely applied in fisheries management mainly due to problems in relating lipofuscin levels in wild-caught animals with accumulation curves derived from aquarium-reared animals. | 1 | Applied and Interdisciplinary Chemistry |
The azo group in DEAD is a Michael acceptor. In the presence of a copper(II) catalyst, DEAD assists conversion of β-keto esters to the corresponding hydrazine derivatives.
The substitution of boronic acid esters proceeds similarly: | 0 | Theoretical and Fundamental Chemistry |
Salahuddin was President of Society of Biological Chemists SBC (India) from 1989 to 1990; a Member of the editorial board of Indian Journal of Biochemistry and Biophysics(1985–1988); Visiting Associate Professor, University of Maryland 1975; Member of Protein Society, Bethesda, USA(1995-1997); Member of the New York Academy of Science, New York(1995-1996); Member of the executive committee of the Society of Biological Chemists, India(1974-1975); Member of the executive committee of Indian Biophysical Society, India (1991–1993); Member of the Guha Research Conference, India (1987–1992); and Member of Sigma Xi (USA). | 1 | Applied and Interdisciplinary Chemistry |
Impossible Foods, producers of plant-based meat substitutes, use an accelerated heme synthesis process involving soybean root leghemoglobin and yeast, adding the resulting heme to items such as meatless (vegan) Impossible burger patties. The DNA for leghemoglobin production was extracted from the soybean root nodules and expressed in yeast cells to overproduce heme for use in the meatless burgers. This process claims to create a meaty flavor in the resulting products. | 1 | Applied and Interdisciplinary Chemistry |
Turbulent diffusion is the transport of mass, heat, or momentum within a system due to random and chaotic time dependent motions. It occurs when turbulent fluid systems reach critical conditions in response to shear flow, which results from a combination of steep concentration gradients, density gradients, and high velocities. It occurs much more rapidly than molecular diffusion and is therefore extremely important for problems concerning mixing and transport in systems dealing with combustion, contaminants, dissolved oxygen, and solutions in industry. In these fields, turbulent diffusion acts as an excellent process for quickly reducing the concentrations of a species in a fluid or environment, in cases where this is needed for rapid mixing during processing, or rapid pollutant or contaminant reduction for safety.
However, it has been extremely difficult to develop a concrete and fully functional model that can be applied to the diffusion of a species in all turbulent systems due to the inability to characterize both an instantaneous and predicted fluid velocity simultaneously. In turbulent flow, this is a result of several characteristics such as unpredictability, rapid diffusivity, high levels of fluctuating vorticity, and dissipation of kinetic energy. | 1 | Applied and Interdisciplinary Chemistry |
In 2008 (150 years after his birth), Auer von Welsbach was selected as a main motif for a high-value collectors' coin: the Austrian €25 Fascination Light. The reverse has a partial portrait of Auer on the left-hand side. The sun shines in the middle of the green niobium pill, while several methods of illumination from the gas light from incandescent light bulbs and neon lamps to modern light-emitting diodes spread out around the silver ring.
He was also depicted on postage stamps of 1936, 1954 and 2012. | 1 | Applied and Interdisciplinary Chemistry |
Conceptually, the in vivo bioreactor was borne from complications in a repair method of bone fracture, bone loss, necrosis, and tumor reconstruction known as bone grafting. Traditional bone grafting strategies require fresh, autologous bone harvested from the iliac crest; this harvest site is limited by the amount of bone that can safely be removed, as well as associated pain and morbidity. Other methods include cadaverous allografts and synthetic options (often made of hydroxyapatite) that have become available in recent years. In response to the question of limited bone sourcing, it has been posited that bone can be grown to fit a damaged region within the body through the application of tissue engineering principles.
Tissue engineering is a biomedical engineering discipline that combines biology, chemistry, and engineering to design neotissue (newly formed tissue) on a scaffold. Tissues scaffolds are functionally identical to the extracellular matrix found, acting as a site upon which regenerative cellular components adsorb to encourage cellular growth. This cellular growth is then artificially stimulated by additive growth factors in the environment that encourage tissue formation. The scaffold is often seeded with stem cells and growth additives to encourage a smooth transition from cells to tissues, and more recently, organs. Traditionally, this method of tissue engineering is performed in vitro, where scaffold components and environmental manipulation recreate in vivo stimuli that direct growth. Environmental manipulation includes changes in physical stimulation, pH, potential gradients, cytokine gradients, and oxygen concentration. The overarching goal of in vitro tissue engineering is to create a functional tissue that is equivalent to native tissue in terms of composition, biomechanical properties, and physiological performance. However, in vitro tissue engineering suffers from a limited ability to mimic in vitro conditions, often leading to inadequate tissue substitutes. Therefore, in vivo tissue engineering has been suggested as a method to circumvent the tedium of environmental manipulation and use native in vivo stimuli to direct cell growth. To achieve in vivo tissue growth, an artificial bioreactor space must be established in which cells may grow. The in vivo bioreactor depends on harnessing the reparative qualities of the body to recruit stem cells into an implanted scaffold, and utilize vasculature to supply all necessary growth components. | 1 | Applied and Interdisciplinary Chemistry |
Ordinary spectroscopy is concerned with the spectra of single atoms or molecules. Here we outline the very different spectra of complexes consisting of two or more interacting atoms or molecules: the "interaction-induced" or "collision-induced" spectroscopy. Both ordinary and collision-induced spectra may be observed in emission and absorption and require an electric or magnetic multipole moment - in most cases an electric dipole moment - to exist for an optical transition to take place from an initial to a final quantum state of a molecule or a molecular complex. (For brevity of expression we will use here the term "molecule" interchangeably for atoms as well as molecules). A complex of interacting molecules may consist of two or more molecules in a collisional encounter, or else of a weakly bound van der Waals molecule. On first sight, it may seem strange to treat optical transitions of a collisional complex, which may exist just momentarily, for the duration of a fly-by encounter (roughly 10 seconds), in much the same way as this was long done for molecules in ordinary spectroscopy. But even transient complexes of molecules may be viewed as a new, "supermolecular" system which is subject to the same spectroscopic rules as ordinary molecules. Ordinary molecules may be viewed as complexes of atoms that have new and possibly quite different spectroscopic properties than the individual atoms the molecule consists of, when the atoms are not bound together as a molecule (or are not "interacting"). Similarly, complexes of interacting molecules may (and usually do) acquire new optical properties, which often are absent in the non-interacting, well separated individual molecules.
Collision-induced absorption (CIA) and emission (CIE) spectra are well known in the microwave and infrared regions of the electromagnetic spectrum, but they occur in special cases also in the visible and near ultraviolet regions. Collision-induced spectra have been observed in nearly all dense gases, and also in many liquids and solids. CIA and CIE are due to the intermolecular interactions, which generate electric dipole moments. We note that an analogous collision-induced light scattering
(CILS) or Raman process also exists, which is well studied and is in many ways completely analogous to CIA and CIE. CILS arises from interaction-induced polarizability increments of molecular complexes; the excess polarizability of a complex, relative the sum of polarizabilities of the noninteracting molecules. | 0 | Theoretical and Fundamental Chemistry |
When exposed to water, the metal oxide that was previously an inner sphere complex will become saturated with water, which is known as a dissolution reaction. This can also be observed in cases where hydroxyl groups are also present.
pH is a consideration within these reactions, but the symmetrical, molecular adsorption of water is considered unstable and possesses a high activation energy.
As a result, the rate determining step relies on the breakage of a critical oxo bond that may increase inductive effects through changes in electron density. This causes nucleophilic attacks and further dissolution to occur. | 0 | Theoretical and Fundamental Chemistry |
Brian Harford Robinson (24 April 1940 – 30 August 2016) was a New Zealand inorganic chemist. He is noted for his contribution to cluster chemistry and the design of organometallic compounds with biomedical applications. | 0 | Theoretical and Fundamental Chemistry |
Zeolites are natural or synthetic crystalline aluminosilicates, which have a repeating pore network and release water at high temperature. Zeolites are polar in nature.
They are manufactured by hydrothermal synthesis of sodium aluminosilicate or another silica source in an autoclave followed by ion exchange with certain cations (Na, Li, Ca, K, NH). The channel diameter of zeolite cages usually ranges from 2 to 9 Å. The ion exchange process is followed by drying of the crystals, which can be pelletized with a binder to form macroporous pellets.
Zeolites are applied in drying of process air, CO removal from natural gas, CO removal from reforming gas, air separation, catalytic cracking, and catalytic synthesis and reforming.
Non-polar (siliceous) zeolites are synthesized from aluminum-free silica sources or by dealumination of aluminum-containing zeolites. The dealumination process is done by treating the zeolite with steam at elevated temperatures, typically greater than . This high temperature heat treatment breaks the aluminum-oxygen bonds and the aluminum atom is expelled from the zeolite framework. | 0 | Theoretical and Fundamental Chemistry |
, about a quarter of annual global greenhouse gas emissions is the carbon dioxide from burning petroleum (plus methane leaks from the industry). Along with the burning of coal, petroleum combustion is the largest contributor to the increase in atmospheric CO. Atmospheric CO has risen over the last 150 years to current levels of over 415 ppmv, from the 180–300 ppmv of the prior 800 thousand years. The rise in Arctic temperature has reduced the minimum Arctic ice pack to , a loss of almost half since satellite measurements started in 1979.
Ocean acidification is the increase in the acidity of the Earth's oceans caused by the uptake of carbon dioxide () from the atmosphere.The saturation state of calcium carbonate decreases with the uptake of carbon dioxide in the ocean. This increase in acidity inhibits all marine life—having a greater effect on smaller organisms as well as shelled organisms (see scallops). | 0 | Theoretical and Fundamental Chemistry |
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