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The near-absence of genetic recombination in mitochondrial DNA makes it a useful source of information for studying population genetics and evolutionary biology. Because all the mitochondrial DNA is inherited as a single unit, or haplotype, the relationships between mitochondrial DNA from different individuals can be represented as a gene tree. Patterns in these gene trees can be used to infer the evolutionary history of populations. The classic example of this is in human evolutionary genetics, where the molecular clock can be used to provide a recent date for mitochondrial Eve. This is often interpreted as strong support for a recent modern human expansion out of Africa. Another human example is the sequencing of mitochondrial DNA from Neanderthal bones. The relatively large evolutionary distance between the mitochondrial DNA sequences of Neanderthals and living humans has been interpreted as evidence for the lack of interbreeding between Neanderthals and modern humans.
However, mitochondrial DNA reflects only the history of the females in a population. This can be partially overcome by the use of paternal genetic sequences, such as the non-recombining region of the Y-chromosome.
Recent measurements of the molecular clock for mitochondrial DNA reported a value of 1 mutation every 7884 years dating back to the most recent common ancestor of humans and apes, which is consistent with estimates of mutation rates of autosomal DNA (10 per base per generation). | 1 | Applied and Interdisciplinary Chemistry |
The isomerization of unsubstituted azulene to naphthalene was the first reported thermal transformation of an aromatic hydrocarbon, and has consequently been the most widely studied rearrangement. However, the following mechanisms are generalized to all thermal isomerizations of aromatic hydrocarbons. Many mechanisms have been suggested for this isomerization, yet none have been unequivocally determined as the only correct mechanism. Five mechanisms were originally considered: a reversible ring-closure mechanism, which is shown above, a norcaradiene-vinylidene mechanism, a diradical mechanism, a methylene walk mechanism, and a spiran mechanism. It was quickly determined that the reversible ring-closure mechanism was inaccurate, and it was later decided that there must be multiple reaction pathways occurring simultaneously. This was widely accepted, as at such high temperatures, one mechanism would have to be substantially energetically favored over the others to be occurring alone. Energetic studies displayed similar activation energies for all possible mechanisms.
Four mechanisms for thermal isomerizations have been proposed: a dyotropic mechanism, a diradical mechanism, and two benzene ring contraction mechanisms; a 1,2-carbon shift to a carbene preceding a 1,2-hydrogen shift, and a 1-2-hydrogen shift to a carbene followed by a 1,2-carbon shift. The dyotropic mechanism involves concerted 1,2-shifts as displayed below. Electronic studies show this mechanism to be unlikely, but it must still be considered a viable mechanism as it has not yet been disproven.
The diradical mechanism has been supported by kinetic studies performed on the reaction, which have revealed that the reaction is not truly unimolecular, as it is most likely initiated by hydrogen addition from another gas-phase species. However, the reaction still obeys first-order kinetics, which is a classical characteristic of radical chain reactions. A mechanistic rational for the thermal rearrangement of azulene to naphthalene is included below. Homolysis of the weakest bond in azulene occurs, followed by a hydrogen shift and ring closure so as to retain the aromaticity of the molecule.
Benzene ring contractions are the last two mechanisms that have been suggested, and they are currently the preferred mechanisms. These reaction mechanisms proceed through the lowest free energy transition states compared to the diradical and dyotropic mechanisms. The difference between the two ring contractions is minute however, so it has not been determined which is favored over the other. Both mechanisms are shown as follows for the ring contraction of biphenylene:
The first involves a 1,2-hydrogen shift to a carbene followed by a 1,2-carbon shift on the same C-C bond but in opposite directions. The second differs from the first only by the order of the 1,2-shifts, with the 1,2-carbon shift preceding the 1,2-hydrogen shift.
The four described mechanisms would all result in the isomerization from azulene to naphthalene. Kinetic data and C-labeling have been used to elucidate the correct mechanism, and have led organic chemists to believe that one of the benzene ring contractions is the most likely mechanism through which these isomerizations of aromatic hydrocarbons occur. | 0 | Theoretical and Fundamental Chemistry |
Meromictic lakes are poorly mixed and anoxic bodies of water with strong vertical stratification. While meromictic lakes are frequently categorized as bodies of water with the potential for euxinic conditions, many do not exhibit euxinia. Meromictic lakes are infamous for limnic eruptions. These events usually coincide with nearby tectonic or volcanic activity that disturbs the otherwise stable stratification of meromictic lakes. This can result in the release of immense concentrations of stored toxic gasses from the anoxic bottom waters, such as CO and HS, especially from euxinic meromictic lakes. In high enough concentration, these limnic explosions can be deadly to humans and animals, such as the Lake Nyos disaster in 1986. | 0 | Theoretical and Fundamental Chemistry |
Ram pressure is a pressure exerted on a body moving through a fluid medium, caused by relative bulk motion of the fluid rather than random thermal motion. It causes a drag force to be exerted on the body. Ram pressure is given in tensor form as
where is the density of the fluid; is the momentum flux per second in the direction through a surface with normal in the direction. are the components of the fluid velocity in these directions. The total Cauchy stress tensor is the sum of this ram pressure and the isotropic thermal pressure (in the absence of viscosity).
In the simple case when the relative velocity is normal to the surface, and momentum is fully transferred to the object, the ram pressure becomes | 1 | Applied and Interdisciplinary Chemistry |
Lichens have been shown to degrade polyester resins, as can be seen in archaeological sites in the Roman city of Baelo Claudia in Spain. Lichens can accumulate several environmental pollutants such as lead, copper, and radionuclides. Some species of lichen, such as Parmelia sulcata (called a hammered shield lichen, among other names) and Lobaria pulmonaria (lung lichen), and many in the Cladonia genus, have been shown to produce serine proteases capable of the degradation of pathogenic forms of prion protein (PrP), which may be useful in treating contaminated environmental reservoirs. | 1 | Applied and Interdisciplinary Chemistry |
Glycal is a name for cyclic enol ether derivatives of sugars having a double bond between carbon atoms 1 and 2 of the ring. The term "glycal" should not be used for an unsaturated sugar that has a double bond in any position other than between carbon atoms 1 and 2. | 0 | Theoretical and Fundamental Chemistry |
The detectors used in surface plasmon resonance convert the photons of light reflected off the metallic film into an electrical signal. A position sensing detector (PSD) or charged-coupled device (CCD) may be used to operate as detectors. | 0 | Theoretical and Fundamental Chemistry |
*cis-1,4-polyisoprene (synthetic analogue of rubber) and trans-1,4-polyisoprene (synthetic analogue of gutta percha) are obtained by coordination polymerisation using suitable Ziegler-Natta catalysts.
* Polyhydroxoalkanoates such as poly(3-hydroxobutyrate), poly(hydroxovaleric acid) etc. obtained by polycondensation and polyaddition. Low-molecular weight polylactide and other polyglycolides can also be obtained by chemical synthesis.
*Oligonucleotides and polynucleotides (DNA or RNA) can be obtain by chemical synthesis through a variety of established approaches.
*A variety of proteins have been obtained by chemical synthesis. A successful approach relies on native chemical ligation, which achieves the synthesis of proteins by linking shorter unprotected peptides. This strategy allowed to obtain, amongst many others, proteins such as insulin-like growth factor 1, the precursor of Aequorea green fluorescent protein and the influenza A virus M2 membrane protein. | 1 | Applied and Interdisciplinary Chemistry |
For very short time scales, a time derivative of flux may be added to Darcys law, which results in valid solutions at very small times (in heat transfer, this is called the modified form of Fouriers law),
where is a very small time constant which causes this equation to reduce to the normal form of Darcy's law at "normal" times (> nanoseconds). The main reason for doing this is that the regular groundwater flow equation (diffusion equation) leads to singularities at constant head boundaries at very small times. This form is more mathematically rigorous but leads to a hyperbolic groundwater flow equation, which is more difficult to solve and is only useful at very small times, typically out of the realm of practical use. | 1 | Applied and Interdisciplinary Chemistry |
The competitive hybridization assay is similar to a traditional competitive immunoassay. Like other hybridization assays, it relies on complementarity, where the capture probe competes between the analyte and the tracer–a labelled oligonucleotide analog to the analyte. | 1 | Applied and Interdisciplinary Chemistry |
Frequency domain (FD) sensor is an instrument developed for measuring soil moisture content. The instrument has an oscillating circuit, the sensing part of the sensor is embedded in the soil, and the operating frequency will depend on the value of soil's dielectric constant. | 0 | Theoretical and Fundamental Chemistry |
An index of biological integrity (IBI), also called an index of biotic integrity, is a scientific tool typically used to identify and classify water pollution problems, although there have been some efforts to apply the idea to terrestrial environments. An IBI associates anthropogenic influences on a water body with biological activity in the water body, and is formulated using data developed from biosurveys. Biological integrity is associated with how "pristine" an environment is and its function relative to the potential or original state of an ecosystem before human alterations were imposed. Biological integrity is built on the assumption that a decline in the values of an ecosystem's functions are primarily caused by human activity or alterations. The more an environment and its original processes are altered, then by definition, the less biological integrity it holds for the community as a whole. If these processes were to change over time naturally, without human influence, the integrity of the ecosystem would remain intact. Similar to the concept of ecosystem health, the integrity of the ecosystem relies heavily on the processes that occur within it because those determine which organisms can inhabit an area and the complexities of their interactions. Deciding which of the many possible states or conditions of an ecosystem is appropriate or desirable is a political or policy decision. | 1 | Applied and Interdisciplinary Chemistry |
* 2023 Analytical Scientist the Power List - Leaders and Advocates
* 2020 Society for Glycobiology Molecular and Cellular Proteomics (MCP) / American Society for Biochemistry and Molecular Biology (ASBMB) Lectureship Award
* 2019 inaugural winner of the US Human Proteome Organization Lifetime Achievement in Proteomics Award
* 2019 Analytical Scientist the Power List
* 2017 American Society for Mass Spectrometry John B. Fenn Award for a Distinguished Contribution in Mass Spectrometry
* 2016 American Association for the Advancement of Science Fellow
* 2015 Human Proteome Organization Distinguished Service Award
* 2015 German Mass Spectrometry Society (Deutsche Gesellschaft für Massenspektrometrie, DGMS) Wolfgang Paul Lecture
* 2013 Boston University The William Fairfield Warren Distinguished Professorship
* 2011 American Chemical Society Fellow
* 2010 American Chemical Society Frank H. Field and Joe L. Franklin Award for Outstanding Achievement in Mass Spectrometry
* 2009 International Mass Spectrometry Foundation Thomson Medal
* 2008 Human Proteome Organization Discovery in Proteomic Sciences Award | 1 | Applied and Interdisciplinary Chemistry |
Let be primitive translation vectors (shortly called primitive vectors) of a crystal lattice , where atoms are located at lattice points described by with , , and as any integers. (So indicating each lattice point is an integer linear combination of the primitive vectors.)
Let be the wave vector of an incoming (incident) beam or wave toward the crystal lattice , and let be the wave vector of an outgoing (diffracted) beam or wave from . Then the vector , called the scattering vector or transferred wave vector, measures the difference between the incoming and outgoing wave vectors.
The three conditions that the scattering vector must satisfy, called the Laue equations, are the following:
where numbers are integer numbers. Each choice of integers , called Miller indices, determines a scattering vector . Hence there are infinitely many scattering vectors that satisfy the Laue equations as there are infinitely many choices of Miller indices . Allowed scattering vectors form a lattice , called the reciprocal lattice of the crystal lattice , as each indicates a point of . (This is the meaning of the Laue equations as shown below.) This condition allows a single incident beam to be diffracted in infinitely many directions. However, the beams corresponding to high Miller indices are very weak and can't be observed. These equations are enough to find a basis of the reciprocal lattice (since each observed indicates a point of the reciprocal lattice of the crystal under the measurement), from which the crystal lattice can be determined. This is the principle of x-ray crystallography. | 0 | Theoretical and Fundamental Chemistry |
In 1982, a diver discovered a shipwreck off the shore of Uluburun, Turkey. The ship contained 317 copper ingots in the normal oxhide shape, 36 with only two corner protrusions, 121 shaped like buns, and five shaped like pillows. The oxhide ingots (ingots with two or four protrusions) range in weight from after being cleaned of their corrosion. These ingots were found stacked in four rows following a herringbone pattern. The smooth sides of the ingots faced downwards, and the lowest layer rested on brushwood. There are three whole tin oxhide ingots, and there are many tin ingots cut into quarters or halves, with their corner protrusion(s) still intact. Besides metal ingots, the cargo included ivory, metal jewelry, and Mycenaean, Cypriot, and Canaanite pottery. Tree-ring dating of firewood from the ship gives an approximate date of 1300 BC. More than 160 copper oxhide ingots, 62 bun ingots, and some of the tin oxhide ingots have incised marks typically on their rough sides. Some of these marks—resembling fish, oars, and boats—relate to the sea, and they were probably incised after casting, when the ingot was received or exported.
Recently Yuval Goren proposed that the ten tons of copper ingots, one ton of tin ingots, and the resin stored in the Canaanite jars aboard the ship were one complete package. The recipients of the copper, tin, and resin would have used these materials for bronze casting through the lost-wax technique. | 1 | Applied and Interdisciplinary Chemistry |
Double stranded breaks (DSB) are a threat to all organisms as they can cause cell death and cancer. They can be caused exogenously as a result of radiation and endogenously from errors in replication or encounters with DNA lesions by the replication fork. DSB repair occurs through a variety of different pathways and mechanisms in order to correctly repair these errors. | 1 | Applied and Interdisciplinary Chemistry |
A siphon (; also spelled syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, above the surface of a reservoir, with no pump, but powered by the fall of the liquid as it flows down the tube under the pull of gravity, then discharging at a level lower than the surface of the reservoir from which it came.
There are two leading theories about how siphons cause liquid to flow uphill, against gravity, without being pumped, and powered only by gravity. The traditional theory for centuries was that gravity pulling the liquid down on the exit side of the siphon resulted in reduced pressure at the top of the siphon. Then atmospheric pressure was able to push the liquid from the upper reservoir, up into the reduced pressure at the top of the siphon, like in a barometer or drinking straw, and then over. However, it has been demonstrated that siphons can operate in a vacuum and to heights exceeding the barometric height of the liquid. Consequently, the cohesion tension theory of siphon operation has been advocated, where the liquid is pulled over the siphon in a way similar to the chain fountain. It need not be one theory or the other that is correct, but rather both theories may be correct in different circumstances of ambient pressure. The atmospheric pressure with gravity theory cannot explain siphons in vacuum, where there is no significant atmospheric pressure. But the cohesion tension with gravity theory cannot explain gas siphons, siphons working despite bubbles, and the flying droplet siphon, where gases do not exert significant pulling forces, and liquids not in contact cannot exert a cohesive tension force.
All known published theories in modern times recognize Bernoulli’s equation as a decent approximation to idealized, friction-free siphon operation. | 1 | Applied and Interdisciplinary Chemistry |
This can be prevented by using sodium phosphate () instead of sodium carbonate as softening reagents. What happens is that its molecules will get inside the hair-line crack and block it, as a result of which sodium hydroxide, even if it is there, will not be able to come in contact with iron, and no reaction will be there. Adding tannin or lignin to boiler water blocks the hair-line cracks and prevents infiltration of NaOH into these areas. Adding NaSO to boiler water also blocks the hair-line cracks. | 1 | Applied and Interdisciplinary Chemistry |
In 1934, Hansgirg arrived in the Empire of Japanm where he worked with industrialist Shitagau Noguchi to set up a magnesium plant at the Chosen Nitrogen fertilizer complex in what is now the northern Korean city of Hungnam. Noguchi (through his company Nichitsu) and Winter (American Magnesium Metals corporation) established a subsidiary Japanese magnesium company. Hansgirg took the post of vice president of both American and Japanese magnesium companies, but there were problems with financing. Hansgirg's work was not limited to magnesium. In 1936, he founded a new firm Nitehiuu gemstones, because of the increased demand for jewel bearings for military purposes.
Hansgirg also developed a cracking plant, to break down crude oil into its various component parts. Before leaving Austria, he had designed two applications of a method of producing heavy water using a water gas shift reaction. It is thought that Hansgirg helped the Japanese to produce heavy water in Hungnam, and was suspected by the United States of aiding the Japanese nuclear weapon program. | 0 | Theoretical and Fundamental Chemistry |
In a variety of animal models, PEA seems to have some promise; researchers have been able to demonstrate relevant clinical efficacy in a variety of disorders, from multiple sclerosis to neuropathic pain.
In the mouse forced swimming test, palmitoylethanolamide was comparable to fluoxetine for depression. An Italian study published in 2011 found that PEA reduced the raised intraocular pressure of glaucoma. In a spinal trauma model, PEA reduced the resulting neurological deficit via the reduction of mast cell infiltration and activation. PEA in this model also reduced the activation of microglia and astrocytes. Its activity as an inhibitor of inflammation counteracts reactive astrogliosis induced by beta-amyloid peptide, in a model relevant for neurodegeneration, probably via the PPAR-α mechanism of action. In models of stroke and other CNS trauma, PEA exerted neuroprotective properties. | 1 | Applied and Interdisciplinary Chemistry |
The College of Chemical Sciences is an institute in Sri Lanka. It was established 25 January 2001 during the Diamond Jubilee celebration of the Institute of Chemistry Ceylon.
As per by law 15 of the Institute of Chemistry Ceylon, the College of Chemical Sciences was established to conduct all the educational and training activities of the institute. A statutory committee known as the academic board of the College of Chemical Sciences is appointed annually to promote, conduct and co-ordinate all the education, training and academic affairs of the College of Chemical Sciences. all the formal educational programmes are the immediate responsibility of this board, which is headed by the chairman and includes 14 members, a deputy chairman, a secretary for educational affairs, and an assistant secretary. Additionally, the president of the institute, one of the honorary joint secretaries of the institute, the chairman of the Admissions & Ethical Practices Committee of the institute, and the institute's honorary treasurer are ex officio members of the academic board.
The chief executive officer of the board is the dean appointed by the council. Full-time academic staff members and teaching assistants constitute the academic staff, while the administrative staff is headed by the registrar of the college. An assistant librarian is in charge of the library. A number of other full-time non academic staff comprise the balance staff. A number of visiting academics and teaching assistants drawn from universities, research institutes, and service organisations and well as the private sector carry out the day-to-day teaching activities of the college. | 1 | Applied and Interdisciplinary Chemistry |
The most convenient way of expressing the composition of a generic mixture is by using the mole fractions (written in the gas phase) of the different components (or chemical species: atoms or molecules) present in the system, where
: with , the number of moles of the component i, and , the total number of moles of all the different components present in the mixture.
The standard state of each component in the mixture is taken to be the pure substance, i.e. the pure substance has an activity of one. When activity coefficients are used, they are usually defined in terms of Raoult's law,
where is the Raoults law activity coefficient: an activity coefficient of one indicates ideal behaviour according to Raoults law. | 0 | Theoretical and Fundamental Chemistry |
Atomic nuclei consist of protons and neutrons bound together by the residual strong force. Because protons are positively charged, they repel each other. Neutrons, which are electrically neutral, stabilize the nucleus in two ways. Their copresence pushes protons slightly apart, reducing the electrostatic repulsion between the protons, and they exert the attractive nuclear force on each other and on protons. For this reason, one or more neutrons are necessary for two or more protons to bind into a nucleus. As the number of protons increases, so does the ratio of neutrons to protons necessary to ensure a stable nucleus (see graph at right). For example, although the neutron:proton ratio of is 1:2, the neutron:proton ratio of is greater than 3:2. A number of lighter elements have stable nuclides with the ratio 1:1 (Z = N). The nuclide (calcium-40) is observationally the heaviest stable nuclide with the same number of neutrons and protons. All stable nuclides heavier than calcium-40 contain more neutrons than protons. | 0 | Theoretical and Fundamental Chemistry |
In 1904, scientists were working to piece together the series of products as a radioactive atom disintegrates, and understand which elements are related by the process. At this time, Boltwood showed that old geological samples contain a constant ratio of radium and uranium, and he set out to prove the two are connected. To do so, he attempted to determine radiums parent element by "growing" it from uraniums known product, "uranium X". His attempts were unsuccessful, and he suspected a long half life would make it impossible to "grow" radium in a measurable amount. In 1907, he discovered a new element with a half life of almost 100,000 years before it decays to radium, and he named it "ionium" after the ionizing action of its alpha particles. Boltwood was able to prove that ionium disintegrates to radium, and the full connection to uranium was shown in work by Frederick Soddy in 1919. Once the existence of isotopes was established in 1914, Stefanie Horovitz and Otto Hönigschmid demonstrated that ionium was actually thorium-230, the second known case of an isotope, rather than its own distinct element. However, the work of these two scientists in Vienna, as they precisely measured the atomic weight of lead from radioactive sources, also served to reinforce Boltwood's assertion that lead is the final product in the uranium decay series. | 0 | Theoretical and Fundamental Chemistry |
RNA polymerase II holoenzyme stability determines the number of base pairs that can be transcribed before the holoenzyme loses its ability to transcribe. The length of the CTD is essential for RNA polymerase II stability. RNA polymerase II stability has been shown to be regulated by post-translation proline hydroxylation. The von Hippel–Lindau tumor suppressor protein (pVHL, human GeneID: 7428) complex binds the hyperphosphorylated large subunit of the RNA polymerase II complex, in a proline hydroxylation- and CTD phosphorylation-dependent manner, targeting it for ubiquitination. | 1 | Applied and Interdisciplinary Chemistry |
Archaeal translation is the process by which messenger RNA is translated into proteins in archaea. Not much is known on this subject, but on the protein level it seems to resemble eukaryotic translation.
Most of the initiation, elongation, and termination factors in archaea have homologs in eukaryotes. Shine-Dalgarno sequences only are found in a minority of genes for many phyla, with many leaderless mRNAs probably initiated by scanning. The process of ABCE1 ATPase-based recycling is also shared with eukaryotes.
Being a prokaryote without a nucleus, archaea do perform transcription and translation at the same time like bacteria do. | 1 | Applied and Interdisciplinary Chemistry |
Mammalian cells are well known for their ability to perform therapeutically essential post-translational modifications and express properly folded, glycosylated and functionally active proteins. However, efficacy of mammalian cells may be limited by epigenetic gene silencing and aggresome formation (recombinant protein aggregation). For mammalian cells, synthesised proteins were reported to be secreted into chemically defined media, potentially simplifying protein extraction and purification.
The most prominent example under this class is Chinese Hamster Ovary (CHO) cells utilised for the synthesis of recombinant varicella zoster virus surface glycoprotein (gE) antigen for SHINGRIX. CHO cells are recognised for rapid growth and their ability to offer process versatility. They can also be cultured in suspension-adapted culture in protein-free medium, hence reducing risk of prion-induced contamination. | 1 | Applied and Interdisciplinary Chemistry |
There are several implications of an excess of reducing equivalents: regulation of cellular signaling pathways by decreasing cell growth responses, modification of transcriptional activity, perturbs disulfide bond formation within proteins, increase of mitochondrial malfunction, decrease in cellular metabolism, and cytotoxicity. The over expression of antioxidant enzymatic systems promote the excess production of reducing equivalents resulting in the depletion of ROS and prompting RS in cells. Nuclear factor erythroid 2–related factor 2 (Nrf2) is an important transcription factor that regulates a multitude of genes that code for antioxidant response and after uncontrolled amplification of this signaling pathway RS increases. Although different organelles may each have a different redox status, through probing for factors such as glutathione and hydrogen peroxide (HO), it was determined that reductive stress is present in the endoplasmic reticulum (ER) of senescent cells. Reductive stress is significant in the aging process of a cell and when ER oxidation status is elevated, cellular aging is slowed. In particular, when reductive stress is increased, it may result in many downstream effects such as increased apoptosis, decreased cell survival, and mitochondrial dysfunction—all of which need to be properly regulated to ensure that the needs of the cell are met. Data shows, in an isolated mitochondria, when there is a high ratio of NADH/NAD+, an example of RS, ROS increases significantly in the mitochondrial matrix which results in H2O2 spillover from the mitochondria. Reductive stress has even been suggested to lead to higher probability of cardiomyopathy in humans. This has also been mysteriously linked to the abundant presence of heat shock protein 27 (Hsp27), suggesting that high levels of Hsp27 induce can induce cardiomyopathy. Reductive stress is present in many diseases with abnormalities such as the increase of reducing equivalents, resulting in issues such as hypoxia-induced oxidative stress. A more reductive redox environment promotes cancer metastasis and cancer cells use reductive stress to promote growth and resist anti-cancer agents, such as chemotherapy and radiotherapy. | 1 | Applied and Interdisciplinary Chemistry |
UV light can be used to harden particular glues, resins and inks by causing a photochemical reaction inside those substances. This process of hardening is called ‘curing’. UV curing is adaptable to printing, coating, decorating, stereolithography, and in the assembly of a variety of products and materials. In comparison to other technologies, curing with UV energy may be considered a low-temperature process, a high-speed process, and is a solventless process, as cure occurs via direct polymerization rather than by evaporation. Originally introduced in the 1960s, this technology has streamlined and increased automation in many industries in the manufacturing sector. A primary advantage of curing with ultraviolet light is the speed at which a material can be processed. Speeding up the curing or drying step in a process can reduce flaws and errors by decreasing time that an ink or coating spends wet. This can increase the quality of a finished item, and potentially allow for greater consistency. Another benefit to decreasing manufacturing time is that less space needs to be devoted to storing items which can not be used until the drying step is finished.
Because UV energy has unique interactions with many different materials, UV curing allows for the creation of products with characteristics not achievable via other means. This has led to UV curing becoming fundamental in many fields of manufacturing and technology, where changes in strength, hardness, durability, chemical resistance, and many other properties are required. | 0 | Theoretical and Fundamental Chemistry |
The thermal pressure coefficient can be considered as a fundamental property; it is closely related to various properties such as internal pressure, sonic velocity, the entropy of melting, isothermal compressibility, isobaric expansibility, phase transition, etc. Thus, the study of the thermal pressure coefficient provides a useful basis for understanding the nature of liquid and solid. Since it is normally difficult to obtain the properties by thermodynamic and statistical mechanics methods due to complex interactions among molecules, experimental methods attract much attention.
The thermal pressure coefficient is used to calculate results that are applied widely in industry, and they would further accelerate the development of thermodynamic theory.
Commonly the thermal pressure coefficient may be expressed as functions of temperature and volume. There are two main types of calculation of the thermal pressure coefficient: one is the Virial theorem and its derivatives; the other is the Van der Waals type and its derivatives. | 0 | Theoretical and Fundamental Chemistry |
The hydration reaction of sulfuric acid is highly exothermic, dilution.
As indicated by its acid dissociation constant, sulfuric acid is a strong acid:
: K = 1000 (pK = −3)
The product of this ionization is , the bisulfate anion. Bisulfate is a far weaker acid:
: K = 0.01 (pK = 2)
The product of this second dissociation is , the sulfate anion. | 0 | Theoretical and Fundamental Chemistry |
Ballast tanks on ships contain the fuels for corrosion. Water is one and air is usually present too and the water can become stagnant. Structural integrity is important for safety and to avoid marine pollution. Coatings have become the solution of choice to reduce the amount of corrosion in ballast tanks. Impressed current cathodic protection has also been used. Likewise sacrificial anode cathodic protection is also used. Since chlorides vastly accelerate corrosion, ballast tanks of marine vessels are particularly susceptible. | 1 | Applied and Interdisciplinary Chemistry |
In organisms that perform oxygenic photosynthesis, excess light may lead to photoinhibition, or photoinactivation of the reaction centers, a process that does not necessarily involve chemical damage. When photosynthetic antenna pigments such as chlorophyll are excited by light absorption, unproductive reactions may occur by charge transfer to molecules with unpaired electrons. Because oxygenic phototrophs generate O as a byproduct from the photocatalyzed splitting of water (HO), photosynthetic organisms have a particular risk of forming reactive oxygen species.
Therefore, a diverse suite of mechanisms has developed in photosynthetic organisms to mitigate these potential threats, which become exacerbated under high irradiance, fluctuating light conditions, in adverse environmental conditions such as cold or drought, and while experiencing nutrient deficiencies which cause an imbalance between energetic sinks and sources.
In eukaryotic phototrophs, these mechanisms include non-photochemical quenching mechanisms such as the xanthophyll cycle, biochemical pathways which serve as "relief valves", structural rearrangements of the complexes in the photosynthetic apparatus, and use of antioxidant molecules. Higher plants sometimes employ strategies such as reorientation of leaf axes to minimize incident light striking the surface. Mechanisms may also act on a longer time-scale, such as up-regulation of stress response proteins or down-regulation of pigment biosynthesis, although these processes are better characterized as "photoacclimatization" processes.
Cyanobacteria possess some unique strategies for photoprotection which have not been identified in plants nor in algae. For example, most cyanobacteria possess an Orange Carotenoid Protein (OCP), which serves as a novel form of non-photochemical quenching. Another unique, albeit poorly-understood, cyanobacterial strategy involves the IsiA chlorophyll-binding protein, which can aggregate with carotenoids and form rings around the PSI reaction center complexes to aid in photoprotective energy dissipation. Some other cyanobacterial strategies may involve state-transitions of the phycobilisome antenna complex
, photoreduction of water with the Flavodiiron proteins, and futile cycling of CO | 0 | Theoretical and Fundamental Chemistry |
*Elected to the National Academy of Sciences in 1990.
*Elected as a Fellow of the Royal Society of London in 1962.
*American Academy of Arts and Sciences | 0 | Theoretical and Fundamental Chemistry |
It has recently been shown that the lamellar phase of the APFN/2HO system form multilamellar vesicles under shear rate. | 0 | Theoretical and Fundamental Chemistry |
In NMR systems, the following relation holds absolute true . In most situations (but not in principle) is greater than . The cases in which are rare, but not impossible. | 0 | Theoretical and Fundamental Chemistry |
Hypothermia can happen in most mammals in cold weather and can be fatal. Baby mammals such as kittens are unable to regulate their body temperatures and have a risk of hypothermia if they are not kept warm by their mothers.
Many animals other than humans often induce hypothermia during hibernation or torpor.
Water bears (Tardigrade), microscopic multicellular organisms, can survive freezing at low temperatures by replacing most of their internal water with the sugar trehalose, preventing the crystallization that otherwise damages cell membranes. | 1 | Applied and Interdisciplinary Chemistry |
The effect is detected by NMR spectroscopy, usually using H NMR spectrum, as enhanced absorption or emission signals ("negative peaks"). The effect arises when unpaired electrons (radicals) are generated during a chemical reaction involving heat or light within the NMR tube. The magnetic field in the spectrometer interacts with the magnetic fields that are caused by the spins of the protons. The two spins of protons produce two slightly different energy levels. In normal conditions, slightly more nuclei, about 10 parts in a million are found in the lower energy level. In contrast, CIDNP produces greatly imbalanced populations, with far greater numbers of spins in upper energy level in some products of the reaction and greater numbers in the lower energy level in other products. The spectrometer uses radio frequencies to detect these differences. | 0 | Theoretical and Fundamental Chemistry |
Matte is a term used in the field of pyrometallurgy given to the molten metal sulfide phases typically formed during smelting of copper, nickel, and other base metals. Typically, a matte is the phase in which the principal metal being extracted is recovered prior to a final reduction process (usually converting) to produce blister copper. The matte may also collect some valuable minor constituents such as noble metals, minor base metals, selenium or tellurium. Mattes may also be used to collect impurities from a metal phase, such as in the case of antimony smelting. Molten mattes are insoluble in both slag and metal phases. This insolubility, combined with differences in specific gravities between mattes, slags, and metals, allows for separation of the molten phases. | 1 | Applied and Interdisciplinary Chemistry |
In fluid mechanics, added mass or virtual mass is the inertia added to a system because an accelerating or decelerating body must move (or deflect) some volume of surrounding fluid as it moves through it. Added mass is a common issue because the object and surrounding fluid cannot occupy the same physical space simultaneously. For simplicity this can be modeled as some volume of fluid moving with the object, though in reality "all" the fluid will be accelerated, to various degrees.
The dimensionless added mass coefficient is the added mass divided by the displaced fluid mass – i.e. divided by the fluid density times the volume of the body. In general, the added mass is a second-order tensor, relating the fluid acceleration vector to the resulting force vector on the body. | 1 | Applied and Interdisciplinary Chemistry |
Electric heat tracing, heat tape or surface heating, is a system used to maintain or raise the temperature of pipes and vessels using heat tracing cables. Trace heating takes the form of an electrical heating element run in physical contact along the length of a pipe. The pipe is usually covered with thermal insulation to retain heat losses from the pipe. Heat generated by the element then maintains the temperature of the pipe. Trace heating may be used to protect pipes from freezing, to maintain a constant flow temperature in hot water systems, or to maintain process temperatures for piping that must transport substances that solidify at ambient temperatures. Electric trace heating cables are an alternative to steam trace heating where steam is unavailable or unwanted. | 1 | Applied and Interdisciplinary Chemistry |
The property of hotness is a concern of thermodynamics that should be defined without reference to the concept of heat. Consideration of hotness leads to the concept of empirical temperature. All physical systems are capable of heating or cooling others. With reference to hotness, the comparative terms hotter and colder are defined by the rule that heat flows from the hotter body to the colder.
If a physical system is inhomogeneous or very rapidly or irregularly changing, for example by turbulence, it may be impossible to characterize it by a temperature, but still there can be transfer of energy as heat between it and another system. If a system has a physical state that is regular enough, and persists long enough to allow it to reach thermal equilibrium with a specified thermometer, then it has a temperature according to that thermometer. An empirical thermometer registers degree of hotness for such a system. Such a temperature is called empirical. For example, Truesdell writes about classical thermodynamics: "At each time, the body is assigned a real number called the temperature. This number is a measure of how hot the body is."
Physical systems that are too turbulent to have temperatures may still differ in hotness. A physical system that passes heat to another physical system is said to be the hotter of the two. More is required for the system to have a thermodynamic temperature. Its behavior must be so regular that its empirical temperature is the same for all suitably calibrated and scaled thermometers, and then its hotness is said to lie on the one-dimensional hotness manifold. This is part of the reason why heat is defined following Carathéodory and Born, solely as occurring other than by work or transfer of matter; temperature is advisedly and deliberately not mentioned in this now widely accepted definition.
This is also the reason that the zeroth law of thermodynamics is stated explicitly. If three physical systems, A, B, and C are each not in their own states of internal thermodynamic equilibrium, it is possible that, with suitable physical connections being made between them, A can heat B and B can heat C and C can heat A. In non-equilibrium situations, cycles of flow are possible. It is the special and uniquely distinguishing characteristic of internal thermodynamic equilibrium that this possibility is not open to thermodynamic systems (as distinguished amongst physical systems) which are in their own states of internal thermodynamic equilibrium; this is the reason why the zeroth law of thermodynamics needs explicit statement. That is to say, the relation is not colder than between general non-equilibrium physical systems is not transitive, whereas, in contrast, the relation has no lower a temperature than between thermodynamic systems in their own states of internal thermodynamic equilibrium is transitive. It follows from this that the relation is in thermal equilibrium with is transitive, which is one way of stating the zeroth law.
Just as temperature may be undefined for a sufficiently inhomogeneous system, so also may entropy be undefined for a system not in its own state of internal thermodynamic equilibrium. For example, the temperature of the Solar System is not a defined quantity. Likewise, the entropy of the Solar System is not defined in classical thermodynamics. It has not been possible to define non-equilibrium entropy, as a simple number for a whole system, in a clearly satisfactory way. | 0 | Theoretical and Fundamental Chemistry |
Fine chemicals account for about 4% of the universe of chemicals. The latter, valued at $2,500 billion, is dominated mainly by oil-, gas-, and mineral-derived commodities (~40%) on one hand and a large variety of specialty chemicals at the interface between industry and the public on the other hand (~55%). The global production value of fine chemicals is estimated at $85 billion, of which about 2/3, or $55 billion are produced captively and $30 billion represent the global revenues of the fine chemical industry. The corresponding figures for the major user, the pharmaceutical industry, are $32 billion and $23 billion, respectively. For a number of reasons, such as the lack of statistical data and the somewhat equivocal definition it is not possible to exactly determine the size of the fine chemical market.
In Table 5, the approximately $85 billion fine chemical market is subdivided into major applications according to their relevance, namely, fine chemicals for pharmaceuticals, agrochemicals and specialty chemicals outside life sciences. Furthermore, a distinction is made between captive (in-house) production and merchant market. Pharmaceutical fine chemicals (PFCs) account for two-thirds of the total. Out of the PFC value of $55 billion, about $23 billion (~40%) are traded, and $32 billion (~60%) are the production value of the pharma industry's in-house production. Within life science products, fine chemicals for agro, and —at a distance— for veterinary drugs follow in importance. The production value for fine chemicals used for specialty chemicals other than pharmaceuticals and agrochemicals is estimated at $15 billion. As the leading specialty chemical companies, Akzo Nobel, Dow, DuPont, Evonik, Chemtura and Mitsubishi are backward-integrated, the share of in-house production is estimated at 75%, leaving a merchant market of approximately $5 billion. | 0 | Theoretical and Fundamental Chemistry |
László Tisza (July 7, 1907 – April 15, 2009) was a Hungarian-born American physicist who was Professor of Physics Emeritus at MIT. He was a colleague of famed physicists Edward Teller, Lev Landau and Fritz London, and initiated the two-fluid theory of liquid helium. | 0 | Theoretical and Fundamental Chemistry |
In healthy persons, the intra-individual variation of TSH and thyroid hormones is considerably smaller than the inter-individual variation. This results from a personal set point of thyroid homeostasis. In hypothyroidism, it is impossible to directly access the set point, but it can be reconstructed with methods of systems theory.
A computerised algorithm, called Thyroid-SPOT, which is based on this mathematical theory, has been implemented in software applications. In patients undergoing thyroidectomy it could be demonstrated that this algorithm can be used to reconstruct the personal set point with sufficient precision. | 1 | Applied and Interdisciplinary Chemistry |
Miraculin is a taste modifier, a glycoprotein extracted from the fruit of Synsepalum dulcificum. The berry, also known as the miracle fruit, was documented by explorer Chevalier des Marchais, who searched for many different fruits during a 1725 excursion to its native West Africa.
Miraculin itself does not taste sweet. When taste buds are exposed to miraculin, the protein binds to the sweetness receptors. This causes normally sour-tasting acidic foods, such as citrus, to be perceived as sweet. The effect can last for one or two hours. | 1 | Applied and Interdisciplinary Chemistry |
Although many of Photaki's important contributions were related to peptide synthesis, her scientific work touched on a large number of topics within organic synthesis. In total she published around 50 papers in international English- or German-language chemical journals. | 0 | Theoretical and Fundamental Chemistry |
Quick clay is found only in countries close to the north pole, such as Russia; Canada; Norway; Sweden; and Finland; and in Alaska, United States; since they were glaciated during the Pleistocene epoch. In Canada, the clay is associated primarily with the Pleistocene-era Champlain Sea, in the modern Ottawa Valley, the St. Lawrence Valley, and the Saguenay River regions.
Quick clay has been the underlying cause of many deadly landslides. In Canada alone, it has been associated with more than 250 mapped landslides. Some of these are ancient, and may have been triggered by earthquakes. | 0 | Theoretical and Fundamental Chemistry |
An intergenic region is a stretch of DNA sequences located between genes. Intergenic regions may contain functional elements and junk DNA. | 1 | Applied and Interdisciplinary Chemistry |
Because there are a limited number of photosystems in the electron transport chain, organisms that are photosynthetic must find a way to combat excess light and prevent photo-oxidative stress, and likewise, photoinhibition, at all costs. In an effort to avoid damage to the D1 subunit of PSII and subsequent formation of ROS, the plant cell employs accessory proteins to carry the excess excitation energy from incoming sunlight; namely, the PsBs protein. Elicited by a relatively low luminal pH, plants have developed a rapid response to excess energy by which it is given off as heat and damage is reduced.
The studies of Tibiletti et al. (2016) found that PsBs is the main protein involved in sensing the changes in the pH and can therefore rapidly accumulate in the presence of high light. This was determined by performing SDS-PAGE and immunoblot assays, locating PsBs itself in the green alga, Chlamydomonas reinhardtii. Their data concluded that the PsBs protein belongs to a multigene family termed LhcSR proteins, including the proteins that catalyze the conversion of violaxanthin to zeaxanthin, as previously mentioned. PsBs is involved in the changing the orientation of the photosystems at times of high light to prompt the arrangement of a quenching site in the light harvesting complex.
Additionally, studies conducted by Glowacka et al. (2018) show that a higher concentration of PsBs is directly correlated to inhibiting stomatal aperture. But it does this without affecting COintake and it increases water use efficiency of the plant. This was determined by controlling the expression of PsBs in Nicotinana tabacum by imposing a series of genetic modifications to the plant in order to test for PsBs levels and activity including: DNA transformation and transcription followed by protein expression. Research shows that stomatal conductance is heavily dependent on the presence of the PsBs protein. Thus, when PsBs was overexpressed in a plant, water uptake efficiency was seen to significantly improve, resulting in new methods for prompting higher, more productive crop yields.
These recent discoveries tie together two of the largest mechanisms in phytobiology; these are the influences that the light reactions have upon stomatal aperture via the Calvin Benson Cycle. To elaborate, the Calvin-Benson Cycle, occurring in the stroma of the chloroplast obtains its CO from the atmosphere which enters upon stomatal opening. The energy to drive the Calvin-Benson cycle is a product of the light reactions. Thus, the relationship has been discovered as such: when PsBs is silenced, as expected, the excitation pressure at PSII is increased. This in turn results in an activation of the redox state of Quinone A and there is no change in the concentration of carbon dioxide in the intracellular airspaces of the leaf; ultimately increasing stomatal conductance. The inverse relationship also holds true: when PsBs is over expressed, there is a decreased excitation pressure at PSII. Thus, the redox state of Quinone A is no longer active and there is, again, no change in the concentration of carbon dioxide in the intracellular airspaces of the leaf. All these factors work to have a net decrease of stomatal conductance. | 0 | Theoretical and Fundamental Chemistry |
The use of alloys by humans started with the use of meteoric iron, a naturally occurring alloy of nickel and iron. It is the main constituent of iron meteorites. As no metallurgic processes were used to separate iron from nickel, the alloy was used as it was. Meteoric iron could be forged from a red heat to make objects such as tools, weapons, and nails. In many cultures it was shaped by cold hammering into knives and arrowheads. They were often used as anvils. Meteoric iron was very rare and valuable, and difficult for ancient people to work. | 1 | Applied and Interdisciplinary Chemistry |
α-Ketoisovalerate undergoes hydroxymethylation to give ketopantoate:
:(CH)CHC(O)CO + CHO → HOCH(CH)CC(O)CO
This conversion is catalyzed by ketopantoate hydroxymethyltransferase.
Like many α-ketoacids, α-ketoisovaleric acid is prone to decarboxylation to give isobutyraldehyde:
:(CH)CHC(O)COH → (CH)CHCHO + CO
Genetic engineering has been used to produce the biofuel isobutanol by reduction of isobutyraldehyde obtained from ketoisovalerate. | 1 | Applied and Interdisciplinary Chemistry |
The pitch drop experiment at Trinity College Dublin in Ireland was started in October 1944 by an unknown colleague of the Nobel Prize winner Ernest Walton while he was in the physics department of Trinity College. This experiment, like the one at University of Queensland, was set up to demonstrate the high viscosity of pitch. This physics experiment sat on a shelf in a lecture hall at Trinity College unmonitored for decades as it dripped a number of times from the funnel to the receiving jar below, also gathering layers of dust.
In April 2013, about a decade after the previous pitch drop, physicists at Trinity College noticed that another drip was forming. They moved the experiment to a table to monitor and record the falling drip with a webcam, allowing all present to watch. The pitch dripped around 17:00 IST on 11 July 2013, marking the first time that a pitch drop was successfully recorded on camera.
Based on the results from this experiment, the Trinity College physicists estimated that the viscosity of the pitch is about two million times that of honey, or about 20 billion times the viscosity of water. | 1 | Applied and Interdisciplinary Chemistry |
When excretion of bilirubin glucuronide by the kidney is detected in the urine through urine examination, meaning that a conspicuous amount of conjugated bilirubin is present and circulating in the blood. | 1 | Applied and Interdisciplinary Chemistry |
Ellipsometry measures the complex reflectance ratio of a system, which may be parametrized by the amplitude component and the phase difference . The polarization state of the light incident upon the sample may be decomposed into an s and a p component (the s component is oscillating perpendicular to the plane of incidence and parallel to the sample surface, and the p component is oscillating parallel to the plane of incidence). The amplitudes of the s and p components, after reflection and normalized to their initial value, are denoted by and respectively. The angle of incidence is chosen close to the Brewster angle of the sample to ensure a maximal difference in and . Ellipsometry measures the complex reflectance ratio (a complex quantity), which is the ratio of over :
Thus, is the amplitude ratio upon reflection, and is the phase shift (difference). (Note that the right side of the equation is simply another way to represent a complex number.) Since ellipsometry is measuring the ratio (or difference) of two values (rather than the absolute value of either), it is very robust, accurate, and reproducible. For instance, it is relatively insensitive to scatter and fluctuations and requires no standard sample or reference beam. | 0 | Theoretical and Fundamental Chemistry |
In the sintering of ceramic materials, abnormal grain growth is often viewed as an undesirable phenomenon because rapidly growing grains may lower the hardness of the bulk material through Hall-Petch-type effects. However, the controlled introduction of dopants to bring about controlled AGG may be used to impart fibre-toughening in ceramic materials. Additionally, AGG is undesirable in piezoelectric ceramics, as it may degrade the piezoelectric effect. | 0 | Theoretical and Fundamental Chemistry |
Receptor-linked tyrosine kinases, such as the epidermal growth factor receptor (EGFR), are activated by extracellular ligands, such as the epidermal growth factor (EGF). Binding of EGF to the EGFR activates the tyrosine kinase activity of the cytoplasmic domain of the receptor. The EGFR becomes phosphorylated on tyrosine residues. Docking proteins such as GRB2 contain an SH2 domain that binds to the phosphotyrosine residues of the activated receptor. GRB2 binds to the guanine nucleotide exchange factor SOS by way of the two SH3 domains of GRB2. When the GRB2-SOS complex docks to phosphorylated EGFR, SOS becomes activated. Activated SOS then promotes the removal of GDP from a member of the Ras subfamily (most notably H-Ras or K-Ras). The Ras protein can then bind GTP and become active.
Apart from EGFR, other cell surface receptors that can activate this pathway via GRB2 include Trk A/B, Fibroblast growth factor receptor (FGFR) and PDGFR. | 1 | Applied and Interdisciplinary Chemistry |
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The measurement of contact angles with the captive bubble method could also be useful in the surface analysis of the reverse osmosis membrane in the study of membrane performances. Through the analysis of contact angles, properties of membranes, such as roughness, can be determined. The roughness of membranes, which indicates the effective surface area, can further lead to the investigation in the hydrophilic and hydrophobic properties of the surface. Through studies, a higher contact angle may correspond to a more hydrophobic surface in membrane analysis. In the performance of the captive bubble method in membrane analysis, several factors can have influence on the contact angle, including the bubble volume, liquid types and tensions.
In the apparatus of the captive bubble method in membrane analysis, the membrane sample is attached to a piece of glass, while a J-shaped needle is inserted from below the glass in the liquid to release air bubbles. In this case, the contact angle between the air bubble and the glass surface is recorded as a function of time to investigate the effect of measurement time. | 0 | Theoretical and Fundamental Chemistry |
The tin belt of Southeast Asia extends all the way down to Tasmania, but metals were not exploited in Australia until the arrival of Europeans in the 1780s. | 1 | Applied and Interdisciplinary Chemistry |
With the development of microfabrication and nanotechnology, the study of microfluidics and nanofluidics is drawing more attention. Research on microfluidic found its advantages in DNA analysis, lab-on-a-chip, and micro-TAS. Devices in a microfluidic system include channels, valves, mixers, and pumps. Integration of these microfluidic devices enables sorting, transporting, and mixing of substances within fluids. However, the failure of moving parts in these systems is usually the critical issue and the main drawback. Mechanisms to control flow without using mechanical parts are always desired for reliability and lifetime.
In 1997, Wei, Bard and Feldberg discovered that ion rectification occurs at the tip of a nano-sized pipe. They observed that the surface charge at the wall of a nano-pipet induced a non-neutral electrical potential within the orifice. The electrical potential then modifies the concentration of ion species, resulting in an asymmetric current-voltage characteristic for the current through the pipet.
Transport of ions in the electrolyte can be adjusted by tuning the pH value in a dilute ionic solution, or by introducing an external electrical potential to change the surface charge density of the wall. As an analogy to semiconductor devices, the mechanism to control charge carrier transport in electronic devices was established in the area of nanofluidics. In nanofluidics, the active control of ion transport is realized using nano-scale channels or pores.
Research efforts on micro-scaled fluidic systems started to focus on the rectifying phenomena, which can be seen only in nano-scaled systems. In 2006, Professor Majumdar and Professor Yang in University of California, Berkeley built the first "nanofluidic" transistor. The transistor can be turn on or off by an external electrical signal, allowing the control of ionic fluids in a nano-scaled channel. Their work implies a possibility to create a nanofluidic circuitry with logic functions.
The main researchers in the area of nanofluidic devices include Arun Majumdar and Peidong Yang in University of California - Berkeley, Harold Craighead and Brian Kirbyat Cornell University, Juan Santiago at Stanford University, Albert van den Berg in University of Twente, Zuzanna Siwy in University of California - Irvine, and Mark Shannon in University of Illinois - Urbana-Champaign. | 0 | Theoretical and Fundamental Chemistry |
Molecular glue refers to a class of chemical compounds or molecules that play a crucial role in binding and stabilizing protein-protein interactions in biological systems. These molecules act as "glue" by enhancing the affinity between proteins, ultimately influencing various cellular processes. Molecular glue compounds have gained significant attention in the fields of drug discovery, chemical biology, and fundamental research due to their potential to modulate protein interactions, and thus, impact various cellular pathways. They have unlocked avenues in medicine previously thought to be "undruggable". | 1 | Applied and Interdisciplinary Chemistry |
In addition to gold and silver, Fusarium oxysporum has been used to synthesize zirconia, titanium, cadmium sulfide and cadmium selenide nanosize particles. Cadmium sulfide nanoparticles have also been synthesized by Trametes versicolor, Schizosaccharomyces pombe, and Candida glabrata. The white-rot fungus Phanerochaete chrysosporium has also been demonstrated to be able to synthesize elemental selenium nanoparticles. | 0 | Theoretical and Fundamental Chemistry |
There are six operational steam traction engines on the grounds, with a 1913 Buffalo-Pitts steamroller and a 1909 20 horsepower Case undergoing restoration. The operational steam tractors are an 1895 Russell & Co. 15-30 steam tractor, a 1902 Advance 16-30 steam tractor, a 1912 J.I. Case steam tractor, a 1920 Minneapolis steam tractor, and a 1916 15-30 Russell & Co. Most, if not all, of these tractors can be seen steaming around the grounds during the show days. | 1 | Applied and Interdisciplinary Chemistry |
Rasagiline was tested for efficacy in people with multiple system atrophy in a large randomized, placebo-controlled, double-blind disease-modification trial; the drug failed.
Teva conducted clinical trials attempting to prove that rasagiline did not just treat symptoms, but was a disease-modifying drug - that it actually prevented the death of the dopaminergic neurons that characterize Parkinson's disease and slowed disease progression. They conducted two clinical trials, called TEMPO and ADAGIO, to try to prove this. The FDA advisory committee rejected their claim in 2011, saying that the clinical trial results did not prove that rasagiline was neuroprotective. The main reason was that in one of the trials, the lower dose was effective at slowing progression, but the higher dose was not, and this made no sense in light of standard dose-response pharmacology. | 0 | Theoretical and Fundamental Chemistry |
Pradeep Mathur (born 1955) is an Indian organometallic and cluster chemist and the founder director of the Indian Institute of Technology, Indore. He is a former professor of the Indian Institute of Technology, Mumbai and is known for his studies on mixed metal cluster compounds. He is an elected fellow of the Indian Academy of Sciences The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards, in 2000, for his contributions to chemical sciences. He has also been honoured by the award of an honorary Doctor of Science degree by the University of Keele in the U.K. | 0 | Theoretical and Fundamental Chemistry |
*ERH is adaptable to all soil types and sedimentary bedrock. ERH is also effective in both the vadose and saturated zones. Certain lithologies can limit traditional methods of remediation by preventing a reliable removal/destruction pathway for the contamination of concern. Because electricity can and does travel through any lithology that contains some water, ERH can be effective in any soil type. By forming buoyant steam bubbles during the heating process, ERH creates a carrier gas that transports the contamination of concern up and out of any soil type. ERH is not capable of desiccating the subsurface. In order for the subsurface to conduct electricity, there must be water present in the subsurface. Conductivity will cease before the subsurface is desiccated.
*ERH is commonly applied under active buildings or manufacturing facilities. Electrodes can be installed above grade within a fenced area or below grade to allow for unrestricted surface access to the treatment area.
*Although principally used for contaminant source areas, ERH can be used to achieve low remedial goals such as maximum contaminant levels, MCLs, for drinking water.
*After ERH treatment, elevated subsurface temperatures will slowly cool over a period of months or years and return to ambient. This period with elevated temperatures is an important part of the remediation process. The elevated temperatures will enhance Bioremediation, hydrolysis and iron reductive dehalogenation. | 1 | Applied and Interdisciplinary Chemistry |
15-Crown-5 is a crown ether with the formula (CHO). It is a cyclic pentamer of ethylene oxide that forms complex with various cations, including sodium (Na) and potassium (K); however, it is complementary to Na and thus has a higher selectivity for Na ions. | 0 | Theoretical and Fundamental Chemistry |
Palmitoylethanolamide (PEA) is an endogenous fatty acid amide, and lipid modulator PEA has been studied in in vitro and in vivo systems using exogenously added or dosed compound; there is evidence that it binds to a nuclear receptor, through which it exerts a variety of biological effects, some related to chronic inflammation and pain.
A main target of PEA is proposed to be the peroxisome proliferator-activated receptor alpha (PPAR-α). PEA also has affinity to cannabinoid-like G-coupled receptors GPR55 and GPR119. PEA cannot strictly be considered a classic endocannabinoid because it lacks affinity for the cannabinoid receptors CB1 and CB2. However, primary research supports the conclusion that the presence of PEA (or other structurally related N-acylethanolamines) enhances anandamide activity by an "entourage effect".
Some primary research reports support the conclusion that PEA levels are altered and that the endocannabinoid system (ECS) is "imbalanced" in acute and chronic inflammation. A primary research article, for instance, has reported that the deregulation of cannabinoid receptors and their endogenous ligands accompanies the development and progression of β-amyloid-induced neuroinflammation.
In some primary research studies, PEA has been shown to have anti-inflammatory, anti-nociceptive, neuroprotective, and anticonvulsant properties. | 1 | Applied and Interdisciplinary Chemistry |
Perfluorotributylamine (PFTBA), also referred to as FC43, is an organic compound with the chemical formula . It is a colorless liquid. A molecule of this chemical compound consists of three butyl groups connected to one nitrogen atom, in which all of the hydrogen atoms are replaced with fluorine atoms. The compound is produced for the electronics industry, along with other perfluoroalkylamines. The high degree of fluorination significantly reduces the basicity of the central amine due to electron-withdrawing effects. | 1 | Applied and Interdisciplinary Chemistry |
A patented cultivar of yeast (Saccharomyces cerevisiae CNCM I-3060) marketed as Sel-Plex® has been approved for use in animal fodder:
* U.S. Food and Drug Administration approval for use as a supplement to feed for chickens, turkeys, swine, goats, sheep, horses, dogs, bison, and beef and dairy cows.
* Organic Materials Review Institute approval for use as a feed supplement for all animal species.
* As of 2006, the European Food Safety Authority's Scientific Panel on Additives and Products or Substances used in Animal Feed allows the use of Sel-Plex® in animal fodder for poultry, swine, and bovines, as the selenium is not significantly bio-accumulated by the human consumer. Only a small amount should be used when blending animal feeds, 10x the authorized maximum selenium intake causes a drop in production. Appropriate measures to minimize inhalation exposure to the product should be taken. | 1 | Applied and Interdisciplinary Chemistry |
Despite their modern abundance, due to their small size and fragility, copepods are extremely rare in the fossil record. The oldest known fossils of copepods are from the late Carboniferous (Pennsylvanian) of Oman, around 303 million years old, which were found in a clast of bitumen from a glacial diamictite. The copepods present in the bitumen clast were likely residents of a subglacial lake which the bitumen had seeped upwards through while still liquid, before the clast subsequently solidified and was deposited by glaciers. Though most of the remains were undiagnostic, at least some likely belonged to the extant harpacticoid family Canthocamptidae, suggesting that copepods had already substantially diversified by this time. Possible microfossils of copepods are known from the Cambrian of North America. Transitions to parasitism have occurred within copepods independently at least 14 different times, with the oldest record of this being from damage to fossil echinoids done by cyclopoids from the Middle Jurassic of France, around 168 million years old. | 1 | Applied and Interdisciplinary Chemistry |
An antiporter (also called exchanger or counter-transporter) is an integral membrane protein involved in secondary active transport. It is a type of cotransporter, which means that uses the movement of one In the case of an antiporter, two or more different molecules or ions are moved across a phospholipid membrane, such as the plasma membrane, in opposite directions, one into the cell and one out of the cell. This is in contrast to symporters, which are another type of cotransporter that moves two or more ions in the same direction.
In secondary active transport, one species of solute moves along its electrochemical gradient, allowing a different species to move against its own electrochemical gradient. This mechanism is used by both types of cotransporters. It is different from primary active transport, where ATP directly fuels the movement of solutes against their concentration gradients. Because this movement requires energy, primary active transport is utilized by ATP-powered pumps to move ions and small molecules.
Transport may involve one or more of each type of solute. For example, the Na/Ca exchanger, found in the plasma membrane of many cells, moves three sodium ions in one direction, and one calcium ion in the other. As with sodium in this example, antiporters rely on an established gradient that makes entry of one ion energetically favorable to force the unfavorable movement of a second molecule in the opposite direction. Through their diverse functions, antiporters are involved in various important physiological processes, such as the regulation the strength of cardiac muscle contraction, transport of carbon dioxide by erythrocytes, regulation of cytosolic pH, and accumulation of sucrose in plant vacuoles. | 1 | Applied and Interdisciplinary Chemistry |
Several conditions are needed to produce foam: there must be mechanical work, surface active components (surfactants) that reduce the surface tension, and the formation of foam faster than its breakdown.
To create foam, work (W) is needed to increase the surface area (ΔA):
where γ is the surface tension.
One of the ways foam is created is through dispersion, where a large amount of gas is mixed with a liquid. A more specific method of dispersion involves injecting a gas through a hole in a solid into a liquid. If this process is completed very slowly, then one bubble can be emitted from the orifice at a time as shown in the picture below.
One of the theories for determining the separation time is shown below; however, while this theory produces theoretical data that matches the experimental data, detachment due to capillarity is accepted as a better explanation.
The buoyancy force acts to raise the bubble, which is
where is the volume of the bubble, is the acceleration due to gravity, and ρ is the density of the gas ρ is the density of the liquid. The force working against the buoyancy force is the surface tension force, which is
where γ is the surface tension, and is the radius of the orifice.
As more air is pushed into the bubble, the buoyancy force grows quicker than the surface tension force. Thus, detachment occurs when the buoyancy force is large enough to overcome the surface tension force.
In addition, if the bubble is treated as a sphere with a radius of and the volume is substituted in to the equation above, separation occurs at the moment when
Examining this phenomenon from a capillarity viewpoint for a bubble that is being formed very slowly, it can be assumed that the pressure inside is constant everywhere. The hydrostatic pressure in the liquid is designated by . The change in pressure across the interface from gas to liquid is equal to the capillary pressure; hence,
where R and R are the radii of curvature and are set as positive. At the stem of the bubble, R and R are the radii of curvature also treated as positive. Here the hydrostatic pressure in the liquid has to take in account z, the distance from the top to the stem of the bubble. The new hydrostatic pressure at the stem of the bubble is p(ρ − ρ)z. The hydrostatic pressure balances the capillary pressure, which is shown below:
Finally, the difference in the top and bottom pressure equal the change in hydrostatic pressure:
At the stem of the bubble, the shape of the bubble is nearly cylindrical; consequently, either R or R is large while the other radius of curvature is small. As the stem of the bubble grows in length, it becomes more unstable as one of the radius grows and the other shrinks. At a certain point, the vertical length of the stem exceeds the circumference of the stem and due to the buoyancy forces the bubble separates and the process repeats. | 0 | Theoretical and Fundamental Chemistry |
Glycosidic bonds of the form discussed above are known as O-glycosidic bonds, in reference to the glycosidic oxygen that links the glycoside to the aglycone or reducing end sugar. In analogy, one also considers S-glycosidic bonds (which form thioglycosides), where the oxygen of the glycosidic bond is replaced with a sulfur atom. In the same way, N-glycosidic bonds, have the glycosidic bond oxygen replaced with nitrogen. Substances containing N-glycosidic bonds are also known as glycosylamines. C-glycosyl bonds have the glycosidic oxygen replaced by a carbon; the term "C-glycoside" is considered a misnomer by IUPAC and is discouraged. All of these modified glycosidic bonds have different susceptibility to hydrolysis, and in the case of C-glycosyl structures, they are typically more resistant to hydrolysis. | 0 | Theoretical and Fundamental Chemistry |
Secondary structures in the DNA can result in folding or knotting of DNA template or primers, leading to decreased product yield or failure of the reaction. Hairpins, which consist of internal folds caused by base-pairing between nucleotides in inverted repeats within single-stranded DNA, are common secondary structures and may result in failed PCRs.
Typically, primer design that includes a check for potential secondary structures in the primers, or addition of DMSO or glycerol to the PCR to minimize secondary structures in the DNA template, are used in the optimization of PCRs that have a history of failure due to suspected DNA hairpins. | 1 | Applied and Interdisciplinary Chemistry |
Cyro-EM presents special challenges to model-builders as the observed electron density is frequently insufficient to resolve individual atoms, leading to a higher likelihood of errors.
Geometry-based validation tools similar to those used in X-ray crystallography can be used to highlight implausible modeling choices and guide modeler toward more native-like structures. The CaBLAM method, which only uses Cα atoms, is suitable for low-resolution structures from cyro-EM.
A way to compute the difference density map has been formulated for cyro-EM. Cross-validation using a "free" map, comparable to the use of a free R-factor, is also available. Other methods for checking model-map fit include correlation coefficients, model-map FSC, confidence maps, CryoEF (orientation bias check), and TEMPy SMOC. | 1 | Applied and Interdisciplinary Chemistry |
An MTC provides traceability and assurance to the end user about the quality of the steel used and the process used to produce it.
Typically a European MTC will be produced to EN 10204. High quality steels for pressure vessel of structural purposes will be declared to 2.1 or 2.2 or certificated to 3.1 or 3.2. (EDIT: type is declared not by chapter in the document, but by type name, so edited the numbering)
The MTC will specify the type of certificate, the grade of steel and any addenda. It will also specify the results of chemical and physical examination to allow the purchaser or end user to compare the plate to the requirements of the relevant standards. | 1 | Applied and Interdisciplinary Chemistry |
An isolated electron has an angular momentum and a magnetic moment resulting from its spin. While an electrons spin is sometimes visualized as a literal rotation about an axis, it cannot be attributed to mass distributed identically to the charge. The above classical relation does not hold, giving the wrong result by the absolute value of the electrons -factor, which is denoted :
where is the Bohr magneton.
The gyromagnetic ratio due to electron spin is twice that due to the orbiting of an electron.
In the framework of relativistic quantum mechanics,
where is the fine-structure constant. Here the small corrections to the relativistic result come from the quantum field theory calculations of the anomalous magnetic dipole moment. The electron -factor is known to twelve decimal places by measuring the electron magnetic moment in a one-electron cyclotron:
The electron gyromagnetic ratio is
The electron -factor and are in excellent agreement with theory; see Precision tests of QED for details. | 0 | Theoretical and Fundamental Chemistry |
A study published in 2016, by researchers from the University of South Florida, Canada and the Netherlands, used GRACE satellite data to estimate freshwater flux from Greenland. They concluded that freshwater runoff is accelerating, and could eventually cause a disruption of AMOC in the future, which would affect Europe and North America.
Another study published in 2016, found further evidence for a considerable impact from sea level rise for the U.S. East Coast. The study confirms earlier research findings which identified the region as a hotspot for rising seas, with a potential to divert 3–4 times higher than the global average sea level rise rate. The researchers attribute the possible increase to an ocean circulation mechanism called deep water formation, which is reduced due to AMOC slow down, leading to more warmer water pockets below the surface. Additionally, the study noted: "Our results suggest that higher carbon emission rates also contribute to increased [sea level rise] in this region compared to the global average". | 0 | Theoretical and Fundamental Chemistry |
If the shock absorbers of a vehicle's suspension are filled with magnetorheological fluid instead of a plain oil or gas, and the channels which allow the damping fluid to flow between the two chambers is surrounded with electromagnets, the viscosity of the fluid, and hence the critical frequency of the damper, can be varied depending on driver preference or the weight being carried by the vehicle - or it may be dynamically varied in order to provide stability control across vastly different road conditions. This is in effect a magnetorheological damper. For example, the MagneRide active suspension system permits the damping factor to be adjusted once every millisecond in response to conditions. General Motors (in a partnership with Delphi Corporation) has developed this technology for automotive applications. It made its debut in both Cadillac (Seville STS build date on or after 1/15/2002 with RPO F55) as "Magneride" (or "MR") and Chevrolet passenger vehicles (All Corvettes made since 2003 with the F55 option code) as part of the driver selectable "Magnetic Selective Ride Control (MSRC)" system in model year 2003. Other manufacturers have paid for the use of it in their own vehicles, for example Audi and Ferrari offer the MagneRide on various models.
General Motors and other automotive companies are seeking to develop a magnetorheological fluid based clutch system for push-button four wheel drive systems. This clutch system would use electromagnets to solidify the fluid which would lock the driveshaft into the drive train.
Porsche has introduced magnetorheological engine mounts in the 2010 Porsche GT3 and GT2. At high engine revolutions, the magnetorheological engine mounts get stiffer to provide a more precise gearbox shifter feel by reducing the relative motion between the power train and chassis/body.
As of September 2007, Acura (Honda) has begun an advertising campaign highlighting its use of MR technology in passenger vehicles manufactured for the 2007 MDX model year. | 1 | Applied and Interdisciplinary Chemistry |
The J-coupling or indirect nuclear spin-spin coupling (sometimes also called "scalar" coupling despite the fact that J is a tensor quantity) describes the interaction of nuclear spins through chemical bonds. J-couplings are not always resolved in solids owing to the typically large linewdiths observed in solid state NMR. | 0 | Theoretical and Fundamental Chemistry |
In a gridless ion source, ions are generated by a flow of electrons (no grids). The most common gridless ion source is the end-Hall ion source. Here, the discharge current and the gas flow are used to control the beam current. | 0 | Theoretical and Fundamental Chemistry |
The Debye length arises naturally in the thermodynamic description of large systems of mobile charges. In a system of different species of charges, the -th species carries charge and has concentration at position . According to the so-called "primitive model", these charges are distributed in a continuous medium that is characterized only by its relative static permittivity, .
This distribution of charges within this medium gives rise to an electric potential that satisfies Poisson's equation:
where , is the electric constant, and is a charge density external (logically, not spatially) to the medium.
The mobile charges not only contribute in establishing but also move in response to the associated Coulomb force, .
If we further assume the system to be in thermodynamic equilibrium with a heat bath at absolute temperature , then the concentrations of discrete charges, , may be considered to be thermodynamic (ensemble) averages and the associated electric potential to be a thermodynamic mean field.
With these assumptions, the concentration of the -th charge species is described by the Boltzmann distribution,
where is the Boltzmann constant and where is the mean
concentration of charges of species .
Identifying the instantaneous concentrations and potential in the Poisson equation with their mean-field counterparts in the Boltzmann distribution yields the Poisson–Boltzmann equation:
Solutions to this nonlinear equation are known for some simple systems. Solutions for more general systems may be obtained in the high-temperature (weak coupling) limit, , by Taylor expanding the exponential:
This approximation yields the linearized Poisson–Boltzmann equation
which also is known as the Debye–Hückel equation:
The second term on the right-hand side vanishes for systems that are electrically neutral. The term in parentheses divided by , has the units of an inverse length squared and by
dimensional analysis leads to the definition of the characteristic length scale
that commonly is referred to as the Debye–Hückel length. As the only characteristic length scale in the Debye–Hückel equation, sets the scale for variations in the potential and in the concentrations of charged species. All charged species contribute to the Debye–Hückel length in the same way, regardless of the sign of their charges. For an electrically neutral system, the Poisson equation becomes
To illustrate Debye screening, the potential produced by an external point charge is
The bare Coulomb potential is exponentially screened by the medium, over a distance of the Debye length: this is called Debye screening or shielding (Screening effect).
The Debye–Hückel length may be expressed in terms of the Bjerrum length as
where is the integer charge number that relates the charge on the -th ionic
species to the elementary charge . | 0 | Theoretical and Fundamental Chemistry |
Geminal halide hydrolysis is an organic reaction. The reactants are geminal dihalides with a water molecule or a hydroxide ion. The reaction yields ketones from secondary halides or aldehydes from primary halides. | 0 | Theoretical and Fundamental Chemistry |
The first full synthesis of apixaban was published in 2007. The key step of this reaction is a (3+2)cycloaddition of a p-methoxyphenylchlorohydrazon derivate and a p-iodophenyl-morpholin-dihydropyridin derivate. After the following elimination of HCl and morpholine, the iodine is substituted by 2-piperidinone by copper-catalization and the ethyl esther is converted to an amide (aminolysis). This reaction was registered as a patent in 2009. | 1 | Applied and Interdisciplinary Chemistry |
* Aggregates can form under varying conditions and differ from each other in soil horizon and structure
* Natural aggregates results in what are called peds, whereas artificial aggregates are called clods.
* Clods are formed due to disturbance of the field by ploughing or digging.
* Microbial activity also influences the formation of aggregates. | 0 | Theoretical and Fundamental Chemistry |
During the submerged arc welding process, not all flux turns into slag. Depending on the welding process, 50% to 90% of the flux can be reused. | 1 | Applied and Interdisciplinary Chemistry |
The S-N bond in sulfenamides are labile in a variety of ways. The sulfur atom tends to be the more electrophilic center of the S-N bond. Nucleophilic attack on sulfur can occur by amines, by thiols, and by alkyl-magnesium halides which leads to either new sulfenamide compounds or back to starting compounds such as sulfides and disulfides respectively. Both the nitrogen and sulfur atoms comprising the S-N bond in sulfenamides have lone pairs of electrons in their outer shells, one and two for nitrogen and sulfur respectively. These lone pairs allow for the possibility of forming either higher order bonds(double, triple) or adding new substituent groups to the compound For instance the nitrogen in the S-N bond of 2-hydroxysulfenanilides can oxidized to an imine species with sodium dichromate.
Sulfenamides react with amino-azaheterocycles to form heterocyclic systems (often used as amino protecting groups in various other synthesis reactions). Chlorocarbonylsulfenyl chloride (ClCOSCl) also readily forms S-N bonds with 2-amino-azaheterocycles, but always of a cyclical nature.
A novel variant of the Appel reaction has been noted for sulfenamides. Reaction of o-nitrobenzenesulfenamide with PPh and CCl leads the formation of o-nitro-N-(triphenylphosphorany1idene)-benzenesulfenamide. In this variant reaction the triphenyl phosphine forms a double bonded linkage with nitrogen in the sulfenamide instead of oxygen as is customary in the Appel reaction. Additionally in the traditional Apple reaction the R-OH bond is cleaved leaving oxygen attached to triphenylphosphine. In this variant the S-N bond is not cleaved. | 0 | Theoretical and Fundamental Chemistry |
The first reverberatory furnaces were perhaps in the medieval period, and were used for melting bronze for casting bells. They were first applied to smelting metals in the late 17th century. Sir Clement Clerke and his son Talbot built cupolas or reverberatory furnaces in the Avon Gorge below Bristol in about 1678. In 1687, while obstructed from smelting lead (by litigation), they moved on to copper. In the following decades, reverberatory furnaces were widely adopted for smelting these metals and also tin. They had the advantage over older methods that the fuel was mineral coal, not charcoal or white coal (chopped dried wood).
In the 1690s, they (or associates) applied the reverberatory furnace (in this case known as an air furnace) to melting pig iron for foundry purposes. This was used at Coalbrookdale and various other places, but became obsolete at the end of the 18th century with the introduction of the foundry cupola furnace, which was a kind of small blast furnace, and a quite different species from the reverberatory furnace.
The puddling furnace, introduced by Henry Cort in the 1780s to replace the older finery process, was also a variety of reverberatory furnace. | 1 | Applied and Interdisciplinary Chemistry |
The damage to the cell can be lethal (the cell dies) or sublethal (the cell can repair itself). Cell damage can ultimately lead to health effects which can be classified as either Tissue Reactions or Stochastic Effects according to the International Commission on Radiological Protection. | 0 | Theoretical and Fundamental Chemistry |
Stereotactic radiation is a specialized type of external beam radiation therapy. It uses focused radiation beams targeting a well-defined tumor using extremely detailed imaging scans. Radiation oncologists perform stereotactic treatments, often with the help of a neurosurgeon for tumors in the brain or spine.
There are two types of stereotactic radiation. Stereotactic radiosurgery (SRS) is when doctors use a single or several stereotactic radiation treatments of the brain or spine. Stereotactic body radiation therapy (SBRT) refers to one or several stereotactic radiation treatments with the body, such as the lungs.
Some doctors say an advantage to stereotactic treatments is that they deliver the right amount of radiation to the cancer in a shorter amount of time than traditional treatments, which can often take 6 to 11 weeks. Plus treatments are given with extreme accuracy, which should limit the effect of the radiation on healthy tissues. One problem with stereotactic treatments is that they are only suitable for certain small tumors.
Stereotactic treatments can be confusing because many hospitals call the treatments by the name of the manufacturer rather than calling it SRS or SBRT. Brand names for these treatments include Axesse, Cyberknife, Gamma Knife, Novalis, Primatom, Synergy, X-Knife, TomoTherapy, Trilogy and Truebeam. This list changes as equipment manufacturers continue to develop new, specialized technologies to treat cancers. | 0 | Theoretical and Fundamental Chemistry |
Understanding of electrical matters began in the sixteenth century. During this century, the English scientist William Gilbert spent 17 years experimenting with magnetism and, to a lesser extent, electricity. For his work on magnets, Gilbert became known as the "Father of Magnetism." He discovered various methods for producing and strengthening magnets.
In 1663, the German physicist Otto von Guericke created the first electric generator, which produced static electricity by applying friction in the machine. The generator was made of a large sulfur ball cast inside a glass globe, mounted on a shaft. The ball was rotated by means of a crank and an electric spark was produced when a pad was rubbed against the ball as it rotated. The globe could be removed and used as source for experiments with electricity.
By the mid-18th century the French chemist Charles François de Cisternay du Fay had discovered two types of static electricity, and that like charges repel each other whilst unlike charges attract. Du Fay announced that electricity consisted of two fluids: "vitreous" (from the Latin for "glass"), or positive, electricity; and "resinous," or negative, electricity. This was the two-fluid theory of electricity, which was to be opposed by Benjamin Franklins one-fluid theory' later in the century.
In 1785, Charles-Augustin de Coulomb developed the law of electrostatic attraction as an outgrowth of his attempt to investigate the law of electrical repulsions as stated by Joseph Priestley in England.
In the late 18th century the Italian physician and anatomist Luigi Galvani marked the birth of electrochemistry by establishing a bridge between chemical reactions and electricity on his essay "De Viribus Electricitatis in Motu Musculari Commentarius" (Latin for Commentary on the Effect of Electricity on Muscular Motion) in 1791 where he proposed a "nerveo-electrical substance" on biological life forms.
In his essay Galvani concluded that animal tissue contained a here-to-fore neglected innate, vital force, which he termed "animal electricity," which activated nerves and muscles spanned by metal probes. He believed that this new force was a form of electricity in addition to the "natural" form produced by lightning or by the electric eel and torpedo ray as well as the "artificial" form produced by friction (i.e., static electricity).
Galvanis scientific colleagues generally accepted his views, but Alessandro Volta rejected the idea of an "animal electric fluid," replying that the frogs legs responded to differences in metal temper, composition, and bulk. Galvani refuted this by obtaining muscular action with two pieces of the same material. Nevertheless, Volta's experimentation led him to develop the first practical battery, which took advantage of the relatively high energy (weak bonding) of zinc and could deliver an electrical current for much longer than any other device known at the time. | 0 | Theoretical and Fundamental Chemistry |
An important use of MLPA is to determine relative ploidy. For example, probes may be designed to target various regions of chromosome 21 of a human cell. The signal strengths of the probes are compared with those obtained from a reference DNA sample known to have two copies of the chromosome. If an extra copy is present in the test sample, the signals are expected to be 1.5 times the intensities of the respective probes from the reference. If only one copy is present the proportion is expected to be 0.5. If the sample has two copies, the relative probe strengths are expected to be equal. | 1 | Applied and Interdisciplinary Chemistry |
If taken together with drugs that induce the CYP3A4 cytochrome P450 liver enzyme, levonorgestrel may be metabolized faster and may have lower effectiveness.
These include, but are not limited to barbiturates, bosentan, carbamazepine, felbamate, griseofulvin, oxcarbazepine, phenytoin, rifampin, St. John's wort and topiramate. | 0 | Theoretical and Fundamental Chemistry |
RingGUI allows for an automated processing of ring diffraction images of polycrystalline or powder samples. It can be used to identify the diffraction rings, quantify the interplanar distances and thus characterize or identify the sample material. With known material, it can assist in microscope calibration. The input image is processed as follows:
# beam-stopper detection,
# localization of the ring center,
# quantification of the diffraction profile and estimation of its background intensity,
# identification of the rings in the image (peaks in the profile).
The results can be further processed and visualized in two interactive, functionally interconnected graphical elements:
* Interactive diffraction image – allows the user to improve readability of the diffraction image by removing the beam-stopper, subtracting the background, revealing faint or spotty rings or by crystallographic identification of the depicted rings.
* Diffraction profile – circular average of the image intensities depicts the peaks corresponding to the rings and their match with theoretical values known for given sample material.
Both, the diffraction image as well as diffraction profile can be used to select diffraction rings with a mouse click. The corresponding ring is then highlighted in both graphical representations and details are listed. | 0 | Theoretical and Fundamental Chemistry |
An important example of chemisorption is in heterogeneous catalysis which involves molecules reacting with each other via the formation of chemisorbed intermediates. After the chemisorbed species combine (by forming bonds with each other) the product desorbs from the surface. | 0 | Theoretical and Fundamental Chemistry |
Yeast, and yeast nutrition, is mixed in the syrup. One gram pure yeast consumes approximately 0.2 grams sugar.
Yeasts will usually die out once the alcohol level reaches about 15% due to the toxicity of alcohol on the yeast cells physiology while the more alcohol tolerant Saccharomyces species take over. In addition to S. cerevisiae, Saccharomyces bayanus' is a species of yeast that can tolerate alcohol levels of 17–20%. | 1 | Applied and Interdisciplinary Chemistry |
Allysine is a derivative of lysine that features a formyl group in place of the terminal amine. The free amino acid does not exist, but the allysine residue does. It is produced by aerobic oxidation of lysine residues by the enzyme lysyl oxidase. The transformation is an example of a post-translational modification. The semialdehyde form exists in equilibrium with a cyclic derivative.
Allysine is involved in the production of elastin and collagen. Increased allysine concentration in tissues has been correlated to the presence of fibrosis.
Allysine residues react with sodium 2-naphthol-6-sulfonate to produce a fluorescent bis-naphtol-allysine product. In another assay, allysine-containing proteins are reduced with sodium borohydride to give a peptide containing the 6-hydroxynorleucine (6-hydroxy-2-aminocaproic acid) residue, which (unlike allysine) is stable to proteolysis. | 1 | Applied and Interdisciplinary Chemistry |
The transcriptomes of stem cells and cancer cells are of particular interest to researchers who seek to understand the processes of cellular differentiation and carcinogenesis. A pipeline using RNA-seq or gene array data can be used to track genetic changes occurring in stem and precursor cells and requires at least three independent gene expression data from the former cell type and mature cells.
Analysis of the transcriptomes of human oocytes and embryos is used to understand the molecular mechanisms and signaling pathways controlling early embryonic development, and could theoretically be a powerful tool in making proper embryo selection in in vitro fertilisation. Analyses of the transcriptome content of the placenta in the first-trimester of pregnancy in in vitro fertilization and embryo transfer (IVT-ET) revealed differences in genetic expression which are associated with higher frequency of adverse perinatal outcomes. Such insight can be used to optimize the practice. Transcriptome analyses can also be used to optimize cryopreservation of oocytes, by lowering injuries associated with the process.
Transcriptomics is an emerging and continually growing field in biomarker discovery for use in assessing the safety of drugs or chemical risk assessment.
Transcriptomes may also be used to infer phylogenetic relationships among individuals or to detect evolutionary patterns of transcriptome conservation.
Transcriptome analyses were used to discover the incidence of antisense transcription, their role in gene expression through interaction with surrounding genes and their abundance in different chromosomes. RNA-seq was also used to show how RNA isoforms, transcripts stemming from the same gene but with different structures, can produce complex phenotypes from limited genomes. | 1 | Applied and Interdisciplinary Chemistry |
Sanitation workers are the people responsible for cleaning, maintaining, operating, or emptying a sanitation technology at any step of the sanitation chain. These workers contribute to safe fecal sludge management. | 1 | Applied and Interdisciplinary Chemistry |
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