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* Kronos Bio, President & Chief Executive Officer, Member of the Board of Directors (since 2018)
* Morphic Therapeutics, Member of the Board of Directors (since 2019)
* Bayer, Member of the supervisory board (since 2017)
* InCarda Therapeutics, Member of the Board of Directors (since 2016) | 0 | Theoretical and Fundamental Chemistry |
In anaerobic sediments and soils, 5β-coprostanol is stable for many hundreds of years enabling it to be used as an indicator of past faecal discharges. As such, records of 5β-coprostanol from paleo-environmental archives have been used to further constrain the timing of human settlements in a region, as well as reconstruct relative changes in human populations and agricultural activities over several thousand years. | 1 | Applied and Interdisciplinary Chemistry |
The Big Bang is thought to be the origin of the hydrogen (including all deuterium) and helium in the universe. Hydrogen and helium together account for 98% of the mass of ordinary matter in the universe, while the other 2% makes up everything else. The Big Bang also produced small amounts of lithium, beryllium and perhaps boron. More lithium, beryllium and boron were produced later, in a natural nuclear reaction, cosmic ray spallation.
Stellar nucleosynthesis is responsible for all of the other elements occurring naturally in the universe as stable isotopes and primordial nuclide, from carbon to uranium. These occurred after the Big Bang, during star formation. Some lighter elements from carbon to iron were formed in stars and released into space by asymptotic giant branch (AGB) stars. These are a type of red giant that "puffs" off its outer atmosphere, containing some elements from carbon to nickel and iron. Nuclides with mass number greater than 64 are predominantly produced by neutron capture processes—the s-process and r-process–in supernova explosions and neutron star mergers.
The Solar System is thought to have condensed approximately 4.6 billion years before the present, from a cloud of hydrogen and helium containing heavier elements in dust grains formed previously by a large number of such stars. These grains contained the heavier elements formed by transmutation earlier in the history of the universe.
All of these natural processes of transmutation in stars are continuing today, in our own galaxy and in others. Stars fuse hydrogen and helium into heavier and heavier elements (up to iron), producing energy. For example, the observed light curves of supernova stars such as SN 1987A show them blasting large amounts (comparable to the mass of Earth) of radioactive nickel and cobalt into space. However, little of this material reaches Earth. Most natural transmutation on the Earth today is mediated by cosmic rays (such as production of carbon-14) and by the radioactive decay of radioactive primordial nuclides left over from the initial formation of the Solar System (such as potassium-40, uranium and thorium), plus the radioactive decay of products of these nuclides (radium, radon, polonium, etc.). See decay chain. | 0 | Theoretical and Fundamental Chemistry |
Many reactions in organic chemistry can occur in either an intramolecular or intermolecular senses. Some reactions are by definition intramolecular or are only practiced intramolecularly, e.g.,
* Dieckmann condensation of diesters is the intramolecular version of aldol condensation.
* Madelung synthesis of indoles
* Smiles rearrangement
* Hydroacylation is almost invariably practiced intramolecularly to produce ketones.
:RCHO + CH=CHR → RC(O)CHCHR
* Nazarov cyclization reaction for the synthesis of cyclopentenones
*The Wurtz reaction, involving reductive coupling of alkyl halides, essentially is only useful when conducted intramolecularly. Its utility is illustrated with the synthesis of strained rings:
Some transformations that are enabled or enhanced intramolecularly. For example, the acyloin condensation of diesters almost uniquely produces 10-membered carbocycles, which are difficult to construct otherwise. Another example is the 2+2 cycloaddition of norbornadiene to give quadricyclane. | 0 | Theoretical and Fundamental Chemistry |
An important property of the non-radiative transition between E and A is that it is stronger for m = ±1 and weaker for m = 0. This provides the basis a very useful manipulation strategy, which is called spin state initialisation (or optical spin-polarization). To understand the process, first consider an off-resonance excitation which has a higher frequency (typically 2.32 eV (532 nm)) than the frequencies of all transitions and thus lies in the vibronic bands for all transitions. By using a pulse of this wavelength, one can excite all spin states from A to E. An NV center in the ground state with m = 0 will be excited to the corresponding excited state with m = 0 due to the conservation of spin. Afterwards it decays back to its original state. For a ground state with m = ±1, the situation is different. After the excitation, it has a relatively high probability to decay into the intermediate state A by non-radiative transition and further into the ground state with m = 0. After many cycles, the state of the NV center (independently of whether it started in m = 0 or m = ±1) will end up in the m = 0 ground state. This process can be used to initialize the quantum state of a qubit for quantum information processing or quantum sensing.
Sometimes the polarisability of the NV center is explained by the claim that the transition from E to the ground state with m = ±1 is small, compared to the transition to m = 0. However, it has been shown that the comparatively low decay probability for m = 0 states w.r.t. m = ±1 states into A is enough to explain the polarization. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, recrystallization is a technique used to purify chemicals. By dissolving a mixture of a compound and impurities in an appropriate solvent, either the desired compound or impurities can be removed from the solution, leaving the other behind. It is named for the crystals often formed when the compound precipitates out. Alternatively, recrystallization can refer to the natural growth of larger ice crystals at the expense of smaller ones. | 0 | Theoretical and Fundamental Chemistry |
He was the author of a very important textbook on electromagnetism with the following two editions:
* Corson, D.R. and Lorrain, P. Introduction to electromagnetic fields and waves, W. H. Freeman, 1962.
* Lorrain, P. and Corson, Dale R. Electromagnetic Fields and Waves, 2nd ed., W. H. Freeman, 1970 ().
The latter incorporated some of the ideas of relativistic electromagnetism.
As part of his Ph.D. work in UC Berkeley, Corson was a co-discoverer of the element astatine. In 1987 he was awarded the Public Welfare Medal from the National Academy of Sciences. | 1 | Applied and Interdisciplinary Chemistry |
*Experimental planning, expected properties and appropriate glass compositions can be estimated from similar data.
*Calculation of glass properties based on many independent data sources.
*Scientific understanding of glass composition-property relations.
*Design of glass compositions that are not patented by the competition.
*System design and optimization including design for purpose and design for cost. | 0 | Theoretical and Fundamental Chemistry |
There is a large number of methods for the determination of particle size, and it is important to acknowledge that these different methods are not expected to give identical results. The size of a particle depends on the method used for its measurement, and it is important to choose the method that is most relevant to the application.
The "See also" section covers many of these techniques. In most of them, the particle size is inferred from a measurement of, for example: light scattering; electrical resistance; particle motion, rather than a direct measurement of particle diameter. This enables rapid measurement of a particle size distribution by an instrument, but does require some form of calibration or assumptions regarding the nature of the particles. Most often this includes the assumption of spherical particles, thus giving a result which is an equivalent spherical diameter. Thus, it is usual for measured particle size distributions to be different when comparing the results between different equipment. The most appropriate method to use is normally the one where the method is aligned to the end use of the data.
For example, to choose whether a chemical compound should be measured by dynamic light scattering or laser diffraction, one generally considers the expected size range, the sample type (liquid or solid), the amount of sample available, the chemical stability, as well its application field. If designing a sedimentation vessel, then a sedimentation technique for sizing is most relevant. However, this approach is often not possible, and an alternative technique must be used. An online Expert system to assist in the selection (and elimination) of particle size analysis equipment has been developed. | 0 | Theoretical and Fundamental Chemistry |
An amphibolic pathway is one that can be either catabolic or anabolic based on the availability of or the need for energy. The currency of energy in a biological cell is adenosine triphosphate (ATP), which stores its energy in the phosphoanhydride bonds. The energy is utilized to conduct biosynthesis, facilitate movement, and regulate active transport inside of the cell. Examples of amphibolic pathways are the citric acid cycle and the glyoxylate cycle. These sets of chemical reactions contain both energy producing and utilizing pathways. To the right is an illustration of the amphibolic properties of the TCA cycle.
The glyoxylate shunt pathway is an alternative to the tricarboxylic acid (TCA) cycle, for it redirects the pathway of TCA to prevent full oxidation of carbon compounds, and to preserve high energy carbon sources as future energy sources. This pathway occurs only in plants and bacteria and transpires in the absence of glucose molecules. | 1 | Applied and Interdisciplinary Chemistry |
Oil reservoirs are routinely mapped by injecting a PFT down one bore hole and measuring the concentration at adjacent boreholes. In this way, geologists can build up an image of the reservoir.
Traditional underground high-tension cables are constructed either with internal oil ducts or channels or by the use of a pipe through which the insulated conductor is installed. In either design the system is then filled with pressurised, de-gassed oil. The oils primary function is to improve the insulating properties of the cable but occasionally leaks can occur through cable joints, oil system fittings or cable sheath damage. The leak is initially identified by the loss of liquid from the system, but its location used to involve engineers digging up the road, freezing a section of cable and seeing if the level was still going down, then choosing a new point to dig and re-freeze. It could take several holes to isolate the leak. If a PFT is injected into the oil, there will be a relatively high concentration of PFT above the leak, which can be pin-pointed to within a few feet, requiring only a single hole to be dug right where the leak is.
PFTs have been used to follow air movement, for tracing the flow of pollutants, for example, the Big Bend Regional Aerosol and Visibility Observational study. measuring the effectiveness of ventilation and studying the possible effects of terrorist attacks (for example in New York ).
PFTs have even been used to track ransom money after a kidnapping. | 1 | Applied and Interdisciplinary Chemistry |
Leonard Adleman of the University of Southern California initially developed this field in 1994. Adleman demonstrated a proof-of-concept use of DNA as a form of computation which solved the seven-point Hamiltonian path problem. Since the initial Adleman experiments, advances have occurred and various Turing machines have been proven to be constructible.
Since then the field has expanded into several avenues. In 1995, the idea for DNA-based memory was proposed by Eric Baum who conjectured that a vast amount of data can be stored in a tiny amount of DNA due to its ultra-high density. This expanded the horizon of DNA computing into the realm of memory technology although the in vitro demonstrations were made almost after a decade.
The field of DNA computing can be categorized as a sub-field of the broader DNA nanoscience field started by [http://seemanlab4.chem.nyu.edu/ Ned Seeman] about a decade before Len Adlemans demonstration. Neds original idea in the 1980s was to build arbitrary structures using bottom-up DNA self-assembly for applications in crystallography. However, it morphed into the field of structural DNA self-assembly which as of 2020 is extremely sophisticated. Self-assembled structure from a few nanometers tall all the way up to several tens of micrometers in size have been demonstrated in 2018.
In 1994, Prof. Seemans group demonstrated early DNA lattice structures using a small set of DNA components. While the demonstration by Adleman showed the possibility of DNA-based computers, the DNA design was trivial because as the number of nodes in a graph grows, the number of DNA components required in Adlemans implementation would grow exponentially. Therefore, computer scientists and biochemists started exploring tile-assembly where the goal was to use a small set of DNA strands as tiles to perform arbitrary computations upon growth. Other avenues that were theoretically explored in the late 90's include DNA-based security and cryptography, computational capacity of DNA systems, DNA memories and disks, and DNA-based robotics.
Before 2002, Lila Kari showed that the DNA operations performed by genetic recombination in some organisms are Turing complete.
In 2003, [https://users.cs.duke.edu/~reif/ John Reif's group] first demonstrated the idea of a DNA-based walker that traversed along a track similar to a line follower robot. They used molecular biology as a source of energy for the walker. Since this first demonstration, a wide variety of DNA-based walkers have been demonstrated. | 1 | Applied and Interdisciplinary Chemistry |
Dye completed a Bachelor of Arts degree in Natural Sciences in 1997 at the University of Cambridge, followed by a PhD on the Mechanical effects of welding superalloys in 2000, supervised by Roger Reed. | 1 | Applied and Interdisciplinary Chemistry |
* Kumar, Praveen; Mittal, Amit; Firoz, Mohammad (2020). "Carbon credit issuance: accounting based financial performance". SCMS Journal of Indian Management. 17(2): 111–119. | 1 | Applied and Interdisciplinary Chemistry |
To measure the kinetic isotope effects of enzymatic reactions, biochemists perform in vitro experiments with enzymes and substrates. The goal of these experiments is to measure the difference in the enzymatic reaction rates for the monoisotopic substrate and the substrate with one rare isotope. There are two popularly used techniques in these experiments: Internal competition studies and direct comparison experiments. Both measure position-specific isotope effects. | 0 | Theoretical and Fundamental Chemistry |
In reality, this method is rarely used due to the difficulty of collecting and analysing the gas concentrations. However, by using an assumed value for oxygen consumption, cardiac output can be closely approximated without the cumbersome and time-consuming oxygen consumption measurement. This is sometimes called an assumed Fick determination.
A commonly used value for O consumption at rest is O per minute per square meter of body surface area. | 1 | Applied and Interdisciplinary Chemistry |
Integrating governing equations with respect to r and applying the above discussed boundary conditions will result in: | 1 | Applied and Interdisciplinary Chemistry |
Along with ubiquitination and phosphorylation, methylation is a major biochemical process for modifying protein function. The most prevalent protein methylations affect arginine and lysine residue of specific histones. Otherwise histidine, glutamate, asparagine, cysteine are susceptible to methylation. Some of these products include S-methylcysteine, two isomers of N-methylhistidine, and two isomers of N-methylarginine. | 0 | Theoretical and Fundamental Chemistry |
The enhanced reactivity at pentacoordinated silicon is not fully understood. Corriu and coworkers suggested that greater electropositive character at the pentavalent silicon atom may be responsible for its increased reactivity. Preliminary ab initio calculations supported this hypothesis to some degree, but used a small basis set.
A software program for ab initio calculations, Gaussian 86, was used by Dieters and coworkers to compare tetracoordinated silicon and phosphorus to their pentacoordinate analogues. This ab initio approach is used as a supplement to determine why reactivity improves in nucleophilic reactions with pentacoordinated compounds. For silicon, the 6-31+G* basis set was used because of its pentacoordinated anionic character and for phosphorus, the 6-31G* basis set was used.
Pentacoordinated compounds should theoretically be less electrophilic than tetracoordinated analogues due to steric hindrance and greater electron density from the ligands, yet experimentally show greater reactivity with nucleophiles than their tetracoordinated analogues. Advanced ab initio calculations were performed on series of tetracoordinated and pentacoordinated species to further understand this reactivity phenomenon. Each series varied by degree of fluorination. Bond lengths and charge densities are shown as functions of how many hydride ligands are on the central atoms. For every new hydride, there is one less fluoride.
For silicon and phosphorus bond lengths, charge densities, and Mulliken bond overlap, populations were calculated for tetra and pentacoordinated species by this ab initio approach. Addition of a fluoride ion to tetracoordinated silicon shows an overall average increase of 0.1 electron charge, which is considered insignificant. In general, bond lengths in trigonal bipyramidal pentacoordinate species are longer than those in tetracoordinate analogues. Si-F bonds and Si-H bonds both increase in length upon pentacoordination and related effects are seen in phosphorus species, but to a lesser degree. The reason for the greater magnitude in bond length change for silicon species over phosphorus species is the increased effective nuclear charge at phosphorus. Therefore, silicon is concluded to be more loosely bound to its ligands.
In addition Dieters and coworkers show an inverse correlation between bond length and bond overlap for all series. Pentacoordinated species are concluded to be more reactive because of their looser bonds as trigonal-bipyramidal structures.
By calculating the energies for the addition and removal of a fluoride ion in various silicon and phosphorus species, several trends were found. In particular, the tetracoordinated species have much higher energy requirements for ligand removal than do pentacoordinated species. Further, silicon species have lower energy requirements for ligand removal than do phosphorus species, which is an indication of weaker bonds in silicon. | 0 | Theoretical and Fundamental Chemistry |
Fireproof banknote is a demonstration of putting a banknote, previously soaked in 50% (v/v) alcohol fuel solution, to a flame. The fire is lit and later extinguished by itself without the banknote being burnt. This demonstration can be used to teach about the fire triangle and classes of fire. | 1 | Applied and Interdisciplinary Chemistry |
In March researchers reported that three of five adult subjects who had acute lymphocytic leukemia (ALL) had been in remission for five months to two years after being treated with genetically modified T cells which attacked cells with CD19 genes on their surface, i.e. all B cells, cancerous or not. The researchers believed that the patients' immune systems would make normal T cells and B cells after a couple of months. They were also given bone marrow. One patient relapsed and died and one died of a blood clot unrelated to the disease.
Following encouraging Phase I trials, in April, researchers announced they were starting Phase II clinical trials (called CUPID2 and SERCA-LVAD) on 250 patients at several hospitals to combat heart disease. The therapy was designed to increase the levels of SERCA2, a protein in heart muscles, improving muscle function. The U.S. Food and Drug Administration (FDA) granted this a breakthrough therapy designation to accelerate the trial and approval process. In 2016, it was reported that no improvement was found from the CUPID 2 trial.
In July researchers reported promising results for six children with two severe hereditary diseases had been treated with a partially deactivated lentivirus to replace a faulty gene and after 7–32 months. Three of the children had metachromatic leukodystrophy, which causes children to lose cognitive and motor skills. The other children had Wiskott–Aldrich syndrome, which leaves them to open to infection, autoimmune diseases, and cancer. Follow up trials with gene therapy on another six children with Wiskott–Aldrich syndrome were also reported as promising.
In October researchers reported that two children born with adenosine deaminase severe combined immunodeficiency disease (ADA-SCID) had been treated with genetically engineered stem cells 18 months previously and that their immune systems were showing signs of full recovery. Another three children were making progress. In 2014, a further 18 children with ADA-SCID were cured by gene therapy. ADA-SCID children have no functioning immune system and are sometimes known as "bubble children".
Also in October researchers reported that they had treated six people with haemophilia in early 2011 using an adeno-associated virus. Over two years later all six were producing clotting factor. | 1 | Applied and Interdisciplinary Chemistry |
Austempering is a hardening process that is used on iron-based metals to promote better mechanical properties. The metal is heated into the austenite region of the iron-cementite phase diagram and then quenched in a salt bath or other heat extraction medium that is between temperatures of . The metal is annealed in this temperature range until the austenite turns to bainite or ausferrite (bainitic ferrite + high-carbon austenite).
By changing the temperature for austenitization, the austempering process can yield different and desired microstructures. A higher austenitization temperature can produce a higher carbon content in austenite, whereas a lower temperature produces a more uniform distribution of austempered structure. The carbon content in austenite as a function of austempering time has been established. | 1 | Applied and Interdisciplinary Chemistry |
A fluid flow can be considered as a dynamical system, that is a set of ordinary differential equations that determines the evolution of a Lagrangian trajectory. These equations are called advection equations:
where are the components of the velocity field, which are assumed to be known from the solution of the equations governing fluid flow, such as the Navier-Stokes equations,
and is the physical position. If the dynamical system governing trajectories is chaotic, the integration of a trajectory is extremely sensitive to initial conditions, and neighboring points separate exponentially with time. This phenomenon is called chaotic advection.
Dynamical systems and chaos theory state that at least 3 degrees of freedom are necessary for a dynamic system to be chaotic. Three-dimensional flows have three degrees of freedom corresponding to the three coordinates, and usually result in chaotic advection, except when the flow has symmetries that reduce the number of degrees of freedom. In flows with less than 3 degrees of freedom, Lagrangian trajectories are confined to closed tubes, and shear-induced mixing can only proceed within these tubes.
This is the case for 2-D stationary flows in which there are only two degrees of freedom and . For stationary (time-independent) flows, Lagrangian trajectories of fluid particles coincide with the streamlines of the flow, that are isolines of the stream function. In 2-D, streamlines are concentric closed curves that cross only at stagnation points. Thus, a spot of dyed fluid to be mixed can only explore the region bounded by the most external and internal streamline, on which it is lying at the initial time. Regarding practical applications, this configuration is not very satisfying.
For 2-D unstationary (time-dependent) flows, instantaneous closed streamlines and Lagrangian trajectories do not coincide any more. Hence, Lagrangian trajectories explore a larger volume of the volume, resulting in better mixing. Chaotic advection is observed for most 2-D unstationary flows. A famous example is the blinking vortex flow introduced by Aref, where two fixed rod-like agitators are alternately rotated inside the fluid. Switching periodically the active (rotating) agitator introduces a time-dependency in the flow, which results in chaotic advection. Lagrangian trajectories can therefore escape from closed streamlines, and visit a large fraction of the fluid domain. | 1 | Applied and Interdisciplinary Chemistry |
In 2006 a new polymorph of maleic acid was discovered, 124 years after the first crystal form was studied. Maleic acid is manufactured on an industrial scale in the chemical industry. It forms salt found in medicine. The new crystal type is produced when a co-crystal of caffeine and maleic acid (2:1) is dissolved in chloroform and when the solvent is allowed to evaporate slowly. Whereas form I has monoclinic space group P2/c, the new form has space group Pc. Both polymorphs consist of sheets of molecules connected through hydrogen bonding of the carboxylic acid groups: in form I, the sheets alternate with respect of the net dipole moment, while in form II, the sheets are oriented in the same direction. | 0 | Theoretical and Fundamental Chemistry |
TSS of a water or wastewater sample is determined by pouring a carefully measured volume of water (typically one litre; but less if the particulate density is high, or as much as two or three litres for very clean water) through a pre-weighed filter of a specified pore size, then weighing the filter again after the drying process that removes all water on the filter. Filters for TSS measurements are typically composed of glass fibres. The gain in weight is a dry weight measure of the particulates present in the water sample expressed in units derived or calculated from the volume of water filtered (typically milligrams per litre or mg/L).
If the water contains an appreciable amount of dissolved substances (as certainly would be the case when measuring TSS in seawater), these will add to the weight of the filter as it is dried. Therefore, it is necessary to "wash" the filter and sample with deionized water after filtering the sample and before drying the filter. Failure to add this step is a fairly common mistake made by inexperienced laboratory technicians working with sea water samples, and will completely invalidate the results as the weight of salts left on the filter during drying can easily exceed that of the suspended particulate matter.
Although turbidity purports to measure approximately the same water quality property as TSS, the latter is preferred when available as it provides an actual weight of the particulate material present in the sample. In water quality monitoring situations, a series of more labor-intensive TSS measurements will be paired with relatively quick and easy turbidity measurements to develop a site-specific correlation. Once satisfactorily established, the correlation can be used to estimate TSS from more frequently made turbidity measurements, saving time and effort. Because turbidity readings are somewhat dependent on particle size, shape, and color, this approach requires calculating a correlation equation for each location. Further, situations or conditions that tend to suspend larger particles through water motion (e.g., increase in a stream current or wave action) can produce higher values of TSS not necessarily accompanied by a corresponding increase in turbidity. This is because particles above a certain size (essentially anything larger than silt) are not measured by a bench turbidity meter (they settle out before the reading is taken), but contribute substantially to the TSS value. | 0 | Theoretical and Fundamental Chemistry |
Both aerobic exercise and strength training (resistance exercise) attenuate myostatin expression, and myostatin inactivation potentiates the beneficial effects of endurance exercise on metabolism. | 1 | Applied and Interdisciplinary Chemistry |
Dissolved organic matter (DOM) is one of the most active and mobile carbon pools and has an important role in global carbon cycling. In addition, dissolved organic carbon (DOC) affects the soil negative electrical charges denitrification process, acid-base reactions in the soil solution, retention and translocation of nutrients (cations), and immobilization of heavy metals and xenobiotics. Soil DOM can be derived from different sources (inputs), such as atmospheric carbon dissolved in rainfall, litter and crop residues, manure, root exudates, and decomposition of soil organic matter (SOM). In the soil, DOM availability depends on its interactions with mineral components (e.g., clays, Fe and Al oxides) modulated by adsorption and desorption processes. It also depends on SOM fractions (e.g., stabilized organic molecules and microbial biomass) by mineralization and immobilization processes. In addition, the intensity of these interactions changes according to soil inherent properties, land use, and crop management.
During the decomposition of organic material, most carbon is lost as CO to the atmosphere by microbial oxidation. Soil type and landscape slope, leaching, and runoff are also important processes associated to DOM losses in the soil. In well-drained soils, leached DOC can reach the water table and release nutrients and pollutants that can contaminate groundwater, whereas runoff transports DOM and xenobiotics to other areas, rivers, and lakes. | 1 | Applied and Interdisciplinary Chemistry |
Source (1990-2012): [http://www.dupont.com/content/dam/assets/corporate-functions/our-approach/science/awards-and%20-recognition/articles/documents/Lavoisier%20Academy.pdf Dupont] ([https://web.archive.org/web/20140707204931/http://www.dupont.com/content/dam/assets/corporate-functions/our-approach/science/awards-and%20-recognition/articles/documents/Lavoisier%20Academy.pdf archived copy])<br>
Source: (2011 onwards): [http://www.dupont.com/corporate-functions/our-approach/innovation-excellence/science/scientists-engineers/awards-and-recognition/articles/lavoisier-medalists.html Dupont] ([https://web.archive.org/web/20190328234336/http://www.dupont.com/corporate-functions/our-approach/innovation-excellence/science/scientists-engineers/awards-and-recognition/articles/lavoisier-medalists.html archived copy])
:* 1990: Dr. Charles W. Todd
:* 1990: Thomas H. Chilton (posthumously awarded).
:* 1990: Nathaniel Wyeth
:* 1991: Crawford Greenewalt
:* 1992: Herman E. Schroeder
:* 1993: Donald R. Johnson Pioneer of automatic clinical diagnostic instrumentation-Dupont Lavoisier Medal
:* 1995: Stephanie Kwolek
:* 1995: Herbert S. Eleuterio
:* 1996: Owen Wright Webster
:* 1997: William C. Drinkard
:* 1997: Charles Stine
:* 1999: Albert Moore
:* 2000: Ivan Maxwell Robinson
:* 2002: Wilfred Sweeny
:* 2003: Rudolph Pariser
:* 2005: Vlodek Gabara, Harry Kamack, Mel Kohan
:* 2007: Edward J. Deyrup, Charles Joseph Noelke
:* 2008: D. Peter Carlson, Noel C. Scrivner
:* 2009: Calvin Chi-Ching Chien, George P. Lahm
:* 2010: Robert L. Segebart
:* 2011: Marc C. Albertsen
:* 2012: Scott V. Tingey
:* 2013: Mario Nappa
:* 2014: Steve Taylor, Dave Estell
:* 2015: Stephen Smith, Ronald McKinney
:* 2016: Mick Ward, Tom Carney
:* 2017: Joe Lachowski, George Weber
:* 2018: Andrew Morgan, Scott Power, Peter Trefonas
:* 2019: Mark Lamontia
:* 2020: Andrew Morgan
:* 2021: Mark Barger, Peter Berg
:* 2022: Theresa Weston, Todd Buley | 1 | Applied and Interdisciplinary Chemistry |
A clepsydra is a clock that measures time by the flow of water. It consists of a pot with a small hole at the bottom through which the water can escape. The amount of escaping water gives the measure of time. As given by the Torricelli's law, the rate of efflux through the hole depends on the height of the water; and as the water level diminishes, the discharge is not uniform. A simple solution is to keep the height of the water constant. This can be attained by letting a constant stream of water flow into the vessel, the overflow of which is allowed to escape from the top, from another hole. Thus having a constant height, the discharging water from the bottom can be collected in another cylindrical vessel with uniform graduation to measure time. This is an inflow clepsydra.
Alternatively, by carefully selecting the shape of the vessel, the water level in the vessel can be made to decrease at constant rate. By measuring the level of water remaining in the vessel, the time can be measured with uniform graduation. This is an example of outflow clepsydra. Since the water outflow rate is higher when the water level is higher (due to more pressure), the fluid's volume should be more than a simple cylinder when the water level is high. That is, the radius should be larger when the water level is higher. Let the radius increase with the height of the water level above the exit hole of area That is, . We want to find the radius such that the water level has a constant rate of decrease, i.e. .
At a given water level , the water surface area is . The instantaneous rate of change in water volume is
From Torricelli's law, the rate of outflow is
From these two equations,
Thus, the radius of the container should change in proportion to the quartic root of its height,
Likewise, if the shape of the vessel of the outflow clepsydra cannot be modified according to the above specification, then we need to use non-uniform graduation to measure time. The emptying time formula above tells us the time should be calibrated as the square root of the discharged water height, More precisely,
where is the time taken by the water level to fall from the height of to height of . | 1 | Applied and Interdisciplinary Chemistry |
One of the most direct evidence for absence of magnetic ordering give NMR or μSR experiments. If there is a local magnetic field present, the nuclear or muon spin would be affected which can be measured. H-NMR measurements on κ-(BEDT-TTF)Cu(CN) have shown no sign of magnetic ordering down to 32 mK, which is four orders of magnitude smaller than the coupling constant J≈250 K between neighboring spins in this compound. Further investigations include:
* Specific heat measurements give information about the low-energy density of states, which can be compared to theoretical models.
* Thermal transport measurements can determine if excitations are localized or itinerant.
* Neutron scattering gives information about the nature of excitations and correlations (e.g. spinons).
* Reflectance measurements can uncover spinons, which couple via emergent gauge fields to the electromagnetic field, giving rise to a power-law optical conductivity. | 0 | Theoretical and Fundamental Chemistry |
The Journal of Electroanalytical Chemistry is a peer-reviewed scientific journal on electroanalytical chemistry, published by Elsevier twice per month. It was originally established in 1959 under the current name, but was known as the Journal of Electroanalytical Chemistry and Interfacial Electrochemistry from 1967 to 1991. It is currently edited by X.-H. Xia (Nanjing University). The journal is associated with the International Society of Electrochemistry. While the journal is now published exclusively in English, earlier volumes sometimes published articles in French and German.
The journal, which The New York Times described as "a specialty publication not widely circulated" in 1990, became more broadly known in 1989 when Martin Fleischmann and Stanley Pons published a description of their controversial cold fusion research in it, withdrawing their work from publication in Nature after questions were raised during peer review there. | 0 | Theoretical and Fundamental Chemistry |
Fourier-transform spectroscopy is a measurement technique whereby spectra are collected based on measurements of the coherence of a radiative source, using time-domain or space-domain measurements of the radiation, electromagnetic or not. It can be applied to a variety of types of spectroscopy including optical spectroscopy, infrared spectroscopy (FTIR, FT-NIRS), nuclear magnetic resonance (NMR) and magnetic resonance spectroscopic imaging (MRSI), mass spectrometry and electron spin resonance spectroscopy.
There are several methods for measuring the temporal coherence of the light (see: field-autocorrelation), including the continuous-wave and the pulsed Fourier-transform spectrometer or Fourier-transform spectrograph.
The term "Fourier-transform spectroscopy" reflects the fact that in all these techniques, a Fourier transform is required to turn the raw data into the actual spectrum, and in many of the cases in optics involving interferometers, is based on the Wiener–Khinchin theorem. | 0 | Theoretical and Fundamental Chemistry |
AR STAT2 deficiency was first time observed in 2 siblings. After routine immunization with measles-mump-rubella, one sibling developed disseminated vaccine-strain measles (MMR) but recovered and second sibling died in infancy from a viral infection due to primary immunodeficiency disorder. Later, the results showed that siblings were homozygous for absent expression of gene for STAT2. Patients with AR STAT2 deficiency have mutations which bring substitutions at important splice sites what leads to defected splicing and premature stop codons leading to a loss of expression of an interferon-stimulated gene. The typical clinical phenotype is disseminated infection after immunization with the live attenuated MMR vaccine. Some patients had also an onset of severe disease in infancy like infection with RSV, norovirus, coxsackievirus, adenovirus or enterovirus. One of the patients had CNS disease after the primary infection with EBV. EBV suppression was delayed in peripheral blood and cerebrospinal fluid as type I interferon signalling plays important role in the initial immune response against EBV. During next 3 years, PCR test showed persistent EBV presence in blood as well as in cerebrospinal fluid despite anti-EBV IgG. CMV and VZV infections were severe as well in few patients. The virus infection was treated by high-dose of intravenous immunoglobulin (IVIG) after which patients recovered and became afebrile within 24 hours. IVIG has anti-inflammatory effect and suggests that the passive immunization could help to control the ongoing viral infections. Therefore, the monthly IgG therapy could be beneficial for patients with STAT2 deficiency during childhood, until their adaptive immune system has sufficiently developed. From the age 5 years, the frequency and severity of viral infections decreased and the age of 10 years the patients were mostly off all medication. In general, the patients with STAT2 deficiency are relatively healthy with no specific defects in their adaptive immunity or developmental abnormalities. These findings show that type I IFN signaling trough ISGF3 is not essential for host defense against the majority of common childhood viral pathogens. Despite a profoundly defective innate IFN response and evident susceptibility to some viral infections, STAT2-deficient individuals can live a relatively healthy life.
It was also reported a homozygous STAT2 missense mutation (R148W/Q) which results to a STAT2 gain of function underlying fatal early-onset autoinflammation in three patients. This mutation leads to a persistent type I IFN response due to defective binding of the mutated STAT2 to ubiquitin specific peptidase 1 (USP18) which is an essential in the negative autofeedback loop where USP18 sterically hinders the binding of JAK1 to IFNAR1. Therefore complete AR STAT2 deficiency usually causes disseminated LAV infection and recurrent natural viral infections. Penetrance is not complete for several viral infections and for complicated live measles vaccine disease. These observation suggest that the phenotype of AR STAT2 deficiency could range from asymptomatic (the healthy adult) to fatal (childhood death from a crushing viral disease). The phenotype is less severe than human complete AR STAT1 deficiency but more severe than IFNAR1 or IFNAR2 deficiency. The human phenotype is less severe than in mice. | 1 | Applied and Interdisciplinary Chemistry |
In the special case where the Prandtl number and turbulent Prandtl number both equal unity (as in the Reynolds analogy), the velocity profile and temperature profiles are identical. This greatly simplifies the solution of the heat transfer problem. If the Prandtl number and turbulent Prandtl number are different from unity, then a solution is possible by knowing the turbulent Prandtl number so that one can still solve the momentum and thermal equations.
In a general case of three-dimensional turbulence, the concept of eddy viscosity and eddy diffusivity are not valid. Consequently, the turbulent Prandtl number has no meaning. | 1 | Applied and Interdisciplinary Chemistry |
A number of organism-specific transcriptome databases have been constructed and annotated to aid in the identification of genes that are differentially expressed in distinct cell populations.
RNA-seq is emerging (2013) as the method of choice for measuring transcriptomes of organisms, though the older technique of DNA microarrays is still used. RNA-seq measures the transcription of a specific gene by converting long RNAs into a library of cDNA fragments. The cDNA fragments are then sequenced using high-throughput sequencing technology and aligned to a reference genome or transcriptome which is then used to create an expression profile of the genes. | 1 | Applied and Interdisciplinary Chemistry |
An ironmaster is the manager, and usually owner, of a forge or blast furnace for the processing of iron. It is a term mainly associated with the period of the Industrial Revolution, especially in Great Britain.
The ironmaster was usually a large-scale entrepreneur and thus an important member of a community. He would have a large country house or mansion as his residence. The organization of operations surrounding the smelting, refining and casting of iron was labour-intensive, and so there would be numerous workers reliant on the furnace works.
There were ironmasters (possibly not called such) from the 17th century onwards, but they became more prominent with the great expansion in the British iron industry during the Industrial Revolution. | 1 | Applied and Interdisciplinary Chemistry |
Lipid molecules in the HII phase pack inversely to the packing observed in the hexagonal I phase described above. This phase has the polar head groups on the inside and the hydrophobic, hydrocarbon tails on the outside in solution. The packing ratio for this phase is larger than one, which is synonymous with an inverse cone packing.
Extended arrays of long tubes will form (as in the hexagonal I phase), but because of the way the polar head groups pack, the tubes take the shape of aqueous channels. These arrays can stack together like pipes. This way of packing may leave a finite hydrophobic surface in contact with water on the outside of the array. However, the otherwise energetically favorable packing apparently stabilizes this phase as a whole. It is also possible that an outer monolayer of lipid coats the surface of the collection of tubes to protect the hydrophobic surface from interaction with the aqueous phase.
It is suggested that this phase is formed by lipids in solution in order to compensate for the hydrophobic effect. The tight packing of the lipid head groups reduces their contact with the aqueous phase. This, in turn, reduces the amount of ordered, but unbound water molecules.
The most common lipids that form this phase include phosphatidylethanolamine (PE), when it has unsaturated hydrocarbon chains. Diphosphatidylglycerol (DPG, otherwise known as cardiolipin) in the presence of calcium is also capable of forming this phase. | 0 | Theoretical and Fundamental Chemistry |
In some larger plants, fat and grease are removed by passing the sewage through a small tank where skimmers collect the fat floating on the surface. Air blowers in the base of the tank may also be used to help recover the fat as a froth. Many plants, however, use primary clarifiers with mechanical surface skimmers for fat and grease removal. | 1 | Applied and Interdisciplinary Chemistry |
A classic example of vinylogy is the relatively high acidity of the γ-hydrogen in . The acidity of the terminal methyl group is similar to that for the methyl ketone .
Vinylogous reactions also include conjugate additions, where a nucleophile reacts at the vinyl terminus, akin to the addition of the nucleophile to the carbonyl of the methyl ketone. In a vinylogous variation of the aldol reaction, an electrophile is attacked by a nucleophilic vinylogous enolate (see first and following image). The vinylogous enolate reacts at the terminal position of the double bond system (the γ-carbon), rather than the α-carbon immediately adjacent to the carbonyl, as would a simple enolate. Allylic electrophiles often react by vinylogous attack of a nucleophile rather than direct addition.
A further example of vinylogous reactivity: ascorbic acid (Vitamin C) behaves as a vinylogous carboxylic acid by involvement of its carbonyl moiety, a vinyl group within the ring, and the lone pair on the hydroxyl group acting as the conjugated system. Acidity of the hydroxyl proton at the terminus of the vinyl group in ascorbic acid is more comparable to a typical carboxylic acid than an alcohol because two major resonance structures stabilize the negative charge on the conjugate base of ascorbic acid (center and right structures in last image), analogous to the two resonance structures that stabilize the negative charge on the anion that results from removal of a proton from a simple carboxylic acid (cf. first image). Analogously, sorbic acid derivatives, extended by another "vinyl" moiety show vinylogous behaviour as well.
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LAGP glass-ceramics can be obtained starting from an amorphous glass with nominal composition of , which is subsequently annealed to promote crystallization. Compared to solid-state sintering, ceramic melt-quenching followed by crystallization is a simpler and more flexible process which leads to a denser and more homogeneous microstructure.
The starting point for glass crystallization is the synthesis of the glass through a melt-quenching process of precursors in suitable amount to achieve the desired stoichiometry. Different precursors can be used, especially to provide phosphorus to the material. One possible route is the following:
* Preheating of AlO and GeO at 1000 °C for 1 hour;
* Drying of LiCO at 300 °C for 3 hours;
* Mixing of the starting precursors in proper amounts to match the nominal stoichiometry;
* Removal of volatile species by stepwise heating of the mix to 500 °C;
* Melting at 1450 °C for 1 hour;
* Quenching of the melt;
* Annealing of glass samples in air.
The main steps are summarized in the following equation:
The annealing temperature is selected to promote the full crystallization and avoiding the formation of detrimental secondary phases, pores, and cracks. Various temperatures are reported in different literature sources; however, crystallization does not usually start below 550-600 °C, while temperatures larger than 850 °C cause the extensive formation of impurity phases. | 0 | Theoretical and Fundamental Chemistry |
Acoustic rheometers employ a piezo-electric crystal that can easily launch a successive wave of extensions and contractions into the fluid. This non-contact method applies an oscillating extensional stress. Acoustic rheometers measure the sound speed and attenuation of ultrasound for a set of frequencies in the megahertz range. Sound speed is a measure of system elasticity. It can be converted into fluid compressibility. Attenuation is a measure of viscous properties. It can be converted into viscous longitudinal modulus. In the case of a Newtonian liquid, attenuation yields information on the volume viscosity. This type of rheometer works at much higher frequencies than others. It is suitable for studying effects with much shorter relaxation times than any other rheometer. | 1 | Applied and Interdisciplinary Chemistry |
Across from each single strand of DNA, we typically see adenine pair with thymine, and cytosine pair with guanine to form a parallel complementary strand as described below. Two nucleotide sequences which correspond to each other in this manner are referred to as complementary:
A frayed end refers to a region of a double stranded (or other multi-stranded) DNA molecule near the end with a significant proportion of non-complementary sequences; that is, a sequence where nucleotides on the adjacent strands do not match up correctly:
The term "frayed" is used because the incorrectly matched nucleotides tend to avoid bonding, thus appearing similar to the strands in a fraying piece of rope.
Although non-complementary sequences are also possible in the middle of double stranded DNA, mismatched regions away from the ends are not referred to as "frayed". | 1 | Applied and Interdisciplinary Chemistry |
Many valves have a spring for spring-loading, to normally shift the disc into some position by default but allow control to reposition the disc. Relief valves commonly use a spring to keep the valve shut, but allow excessive pressure to force the valve open against the spring-loading. Coil springs are normally used. Typical spring materials include zinc plated steel, stainless steel, and for high temperature applications Inconel X750. | 1 | Applied and Interdisciplinary Chemistry |
Usually called molybdenum pentachloride, it is in fact partly a dimer with the molecular formula . In the dimer, each molybdenum has local octahedral symmetry and two chlorides bridge between the molybdenum centers. A similar structure is also found for the pentachlorides of W, Nb and Ta. In the gas phase and partly in solution, the dimers partially dissociate to give a monomeric . The monomer is paramagnetic, with one unpaired electron per Mo center, reflecting the fact that the formal oxidation state is +5, leaving one valence electron on the metal center. | 0 | Theoretical and Fundamental Chemistry |
In nature, denitrification can take place in both terrestrial and marine ecosystems. Typically, denitrification occurs in anoxic environments, where the concentration of dissolved and freely available oxygen is depleted. In these areas, nitrate (NO) or nitrite () can be used as a substitute terminal electron acceptor instead of oxygen (O), a more energetically favourable electron acceptor. Terminal electron acceptor is a compound that gets reduced in the reaction by receiving electrons. Examples of anoxic environments can include soils, groundwater, wetlands, oil reservoirs, poorly ventilated corners of the ocean and seafloor sediments.
Furthermore, denitrification can occur in oxic environments as well. High activity of denitrifiers can be observed in the intertidal zones, where the tidal cycles cause fluctuations of oxygen concentration in sandy coastal sediments. For example, the bacterial species Paracoccus denitrificans engages in denitrification under both oxic and anoxic conditions simultaneously. Upon oxygen exposure, the bacteria is able to utilize nitrous oxide reductase, an enzyme that catalyzes the last step of denitrification. Aerobic denitrifiers are mainly Gram-negative bacteria in the phylum Proteobacteria. Enzymes NapAB, NirS, NirK and NosZ are located in the periplasm, a wide space bordered by the cytoplasmic and the outer membrane in Gram-negative bacteria.
Denitrification can lead to a condition called isotopic fractionation in the soil environment. The two stable isotopes of nitrogen, N and N are both found in the sediment profiles. The lighter isotope of nitrogen, N, is preferred during denitrification, leaving the heavier nitrogen isotope, N, in the residual matter. This selectivity leads to the enrichment of N in the biomass compared to N. Moreover, the relative abundance of N can be analyzed to distinguish denitrification apart from other processes in nature. | 1 | Applied and Interdisciplinary Chemistry |
Jorge Allende was born in Cartago, Costa Rica, son of Octavio Allende Echeverría, Chilean Consul in the city of Puntarenas, and Amparo Rivera Ortiz, a Costa Rican artist. Because of his father's job as a diplomat, he spent his childhood years between Costa Rica, Chile and the United States. He finished high school in a Jesuit School in New Orleans, Louisiana, where his father was appointed as the Chilean Consul. Subsequently, he studied at Louisiana State University in Baton Rouge, Louisiana. He obtained the Bachelor of Science in chemistry degree in 1957. | 1 | Applied and Interdisciplinary Chemistry |
In physics, ferroics is the generic name given to the study of ferromagnets, ferroelectrics, and ferroelastics. | 0 | Theoretical and Fundamental Chemistry |
cellDancer is a scalable deep neural network that locally infers velocity for each cell from its neighbors and then relays a series of local velocities to provide single-cell resolution inference of velocity kinetics. cellDancer improved the extisting hypothesis of kinetic rates of velocyto and scVelo, transcription rate was either a constant (velocyto model) or binary values (scVelo model), splicing and degradation rates were shared by all the genes and cells, which may have unpredictable performance, while cellDancer can predict the specific transcription, splicing and degradation rates of each gene in each cell through deep learning. | 1 | Applied and Interdisciplinary Chemistry |
Deacylations "play crucial roles in gene transcription and most likely in all eukaryotic biological processes that involve chromatin".
Acetylation is one type of post-translational modification of proteins. The acetylation of the ε-amino group of lysine, which is common, converts a charged side chain to a neutral one. Acetylation/deacetylation of histones also plays a role in gene expression and cancer. These modifications are effected by enzymes called histone acetyltransferases (HATs) and histone deacetylases (HDACs).
Two general mechanisms are known for deacetylation. One mechanism involves zinc binding to the acetyl oxygen. Another family of deacetylases require NAD, which transfers an ribosyl group to the acetyl oxygen. | 0 | Theoretical and Fundamental Chemistry |
Native chemical ligation of unprotected peptide segments is used to prepare the protein's polypeptide chain, which is then folded to form a protein molecule. In native chemical ligation, a peptide C-terminal thioester reacts with a second peptide that has a cysteine residue at its N-terminus, to give a product with a peptide bond at the ligation site. Multiple unprotected peptide segments can be linked in this way to give the full length polypeptide chain, which is folded to give the target protein molecule. Once the chemical synthesis of an L-protein is achieved, the D-protein enantiomer can be manufactured using synthetic peptide building blocks made from D-amino acids and Gly. Convergent synthesis is most effective in preparing long polypeptide chains, by using peptide-hydrazides, where the hydrazide can be converted to a thioester for use in native chemical ligation. The hydrazide is stable to native chemical ligation reaction conditions, and can be converted in situ to a reactive peptide-thioester for the next native chemical ligation condensation reaction. | 0 | Theoretical and Fundamental Chemistry |
Some chemists have also considered the 2-norbornyl cation to be best represented by the nortricyclonium ion, a C-symmetric protonated nortricyclene. This depiction was first invoked to partially explain results of a C isotope scrambling experiment. The molecular orbital representation of this structure involves an in-phase interaction between sp-hybridized orbitals from carbons 1, 2 and 6 and the 1s atomic orbital on a shared hydrogen atom (see Figure 5). | 0 | Theoretical and Fundamental Chemistry |
Complexes with the similar salan or salalen ligands, with one or two saturated nitrogen–aryl bonds (amines rather than imines) tend to be less rigid and more electron-rich at the metal center than the corresponding salen complexes. | 0 | Theoretical and Fundamental Chemistry |
The spontaneous assembly of a single layer of molecules at interfaces is usually referred to as two-dimensional self-assembly. One of the common examples of such assemblies are Langmuir-Blodgett monolayers and multilayers of surfactants. Non-surface active molecules can assemble into ordered structures as well. Early direct proofs showing that non-surface active molecules can assemble into higher-order architectures at solid interfaces came with the development of scanning tunneling microscopy and shortly thereafter. Eventually two strategies became popular for the self-assembly of 2D architectures, namely self-assembly following ultra-high-vacuum deposition and annealing and self-assembly at the solid-liquid interface. The design of molecules and conditions leading to the formation of highly-crystalline architectures is considered today a form of 2D crystal engineering at the nanoscopic scale. | 0 | Theoretical and Fundamental Chemistry |
Completely clear filtrate cannot be obtained using belt press filters except in rare circumstances. Thus further treatment may be required for the filtrate before it is reused or discharged as waste. If the filter is downstream of a clarifier or thickener the filtrate (and wash water) can be recycled back into the clarifier to reduce the required filtrate clarity and allows for the use of more durable cloths. If recycling or reuse is not an option the filtrate should be discharged subject to legislation and license requirements. Further treatment of clarified water (filtration or chemical treatment) may be required before discharge.
The filter cake usually has a high enough solid concentration to allow for all types of disposal methods without further treatment including recycling back into the process, landfill/composting and incineration. The polymer content makes filter cake from a belt press filter more suited to the aforementioned disposal methods than a cake conditioned with ferric chloride and lime which can occur with other dewatering processes. | 1 | Applied and Interdisciplinary Chemistry |
A betaine () in chemistry is any neutral chemical compound with a positively charged cationic functional group that bears no hydrogen atom, such as a quaternary ammonium or phosphonium cation (generally: onium ions), and with a negatively charged functional group, such as a carboxylate group that may not be adjacent to the cationic site. Historically, the term was reserved for trimethylglycine (TMG), which is involved in methylation reactions and detoxification of homocysteine. This is a modified amino acid consisting of glycine with three methyl groups serving as methyl donor for various metabolic pathways. | 0 | Theoretical and Fundamental Chemistry |
The Fmoc group is rapidly removed by base. Piperidine is usually preferred for Fmoc group removal as it forms a stable adduct with the dibenzofulvene byproduct, preventing it from reacting with the substrate. | 1 | Applied and Interdisciplinary Chemistry |
Dexmedetomidine was approved in 1999 by the US Food and Drug Administration (FDA) as a short-term sedative and analgesic (<24 hours) for critically ill or injured people on mechanical ventilation in the intensive care unit (ICU). The rationale for its short-term use was due to concerns over withdrawal side effects such as rebound high blood pressure. These effects have not been consistently observed in research studies, however. | 0 | Theoretical and Fundamental Chemistry |
The pioneering work of chemical kinetics was done by German chemist Ludwig Wilhelmy in 1850. He experimentally studied the rate of inversion of sucrose and he used integrated rate law for the determination of the reaction kinetics of this reaction. His work was noticed 34 years later by Wilhelm Ostwald. After Wilhelmy, Peter Waage and Cato Guldberg published 1864 the law of mass action, which states that the speed of a chemical reaction is proportional to the quantity of the reacting substances.
Van t Hoff studied chemical dynamics and in 1884 published his famous "Études de dynamique chimique". In 1901 he was awarded by the first Nobel Prize in Chemistry "in recognition of the extraordinary services he has rendered by the discovery of the laws of chemical dynamics and osmotic pressure in solutions". After van t Hoff, chemical kinetics deals with the experimental determination of reaction rates from which rate laws and rate constants are derived. Relatively simple rate laws exist for zero order reactions (for which reaction rates are independent of concentration), first order reactions, and second order reactions, and can be derived for others. Elementary reactions follow the law of mass action, but the rate law of stepwise reactions has to be derived by combining the rate laws of the various elementary steps, and can become rather complex. In consecutive reactions, the rate-determining step often determines the kinetics. In consecutive first order reactions, a steady state approximation can simplify the rate law. The activation energy for a reaction is experimentally determined through the Arrhenius equation and the Eyring equation. The main factors that influence the reaction rate include: the physical state of the reactants, the concentrations of the reactants, the temperature at which the reaction occurs, and whether or not any catalysts are present in the reaction.
Gorban and Yablonsky have suggested that the history of chemical dynamics can be divided into three eras. The first is the van 't Hoff wave searching for the general laws of chemical reactions and relating kinetics to thermodynamics. The second may be called the Semenov-Hinshelwood wave with emphasis on reaction mechanisms, especially for chain reactions. The third is associated with Aris and the detailed mathematical description of chemical reaction networks. | 0 | Theoretical and Fundamental Chemistry |
Aluminothermy started from the experiments of Russian scientist Nikolay Beketov at the University of Kharkiv in Ukraine, who proved that aluminium restored metals from their oxides under high temperatures. The reaction was first used for the carbon-free reduction of metal oxides. The reaction is highly exothermic, but it has a high activation energy since strong interatomic bonds in the solids must be broken first. The oxide was heated with aluminium in a crucible in a furnace. The runaway reaction made it possible to produce only small quantities of material. Hans Goldschmidt improved the aluminothermic process between 1893 and 1898, by igniting the mixture of fine metal oxide and aluminium powder by a starter reaction without heating the mixture externally. The process was patented in 1898 and used extensively in the later years for rail track welding. | 1 | Applied and Interdisciplinary Chemistry |
DH5-Alpha Cells are E. coli cells engineered by American biologist Douglas Hanahan to maximize transformation efficiency. They are defined by three mutations: recA1, endA1 which help plasmid insertion and lacZΔM15 which enables blue white screening. The cells are competent and often used with calcium chloride transformation to insert the desired plasmid. A study of four transformation methods and six bacteria strains showed that the most efficient one was the DH5 strain with the Hanahan method. | 1 | Applied and Interdisciplinary Chemistry |
Strong field approximation (SFA), or Keldysh-Faisal-Reiss theory is a physical model, started in 1964 by the Russian physicist Keldysh, is currently used to describe the behavior of atoms (and molecules) in intense laser fields.
SFA is the starting theory for discussing both high harmonic generation and attosecond pump-probe interaction with atoms.
The main assumption made in SFA is that the free-electron dynamics is dominated by the laser field, while the Coulomb potential is regarded as a negligible perturbation.
This fact re-shapes equation into:
where, is the Volkov Hamiltonian, here expressed for simplicity in the velocity gauge, with , , the electromagnetic vector potential.
At this point, to keep the discussion at its basic level, lets consider an atom with a single energy level , ionization energy and populated by a single electron (single active electron approximation).
We can consider the initial time of the wave function dynamics as , and we can assume that initially the electron is in the atomic ground state .
So that,
: and
Moreover, we can regard the continuum states as plane-wave functions state, .
This is a rather simplified assumption, a more reasonable choice would have been to use as continuum state the exact atom scattering states.
The time evolution of simple plane-wave states with the Volkov Hamiltonian is given by:
here for consistency with Eq. the evolution has already been properly converted into the length gauge.
As a consequence, the final momentum distribution of a single electron in a single-level atom, with ionization potential , is expressed as:
where,
is the dipole expectation value (or transition dipole moment), and
is the semiclassical action.
The result of Eq. is the basic tool to understand phenomena like:
* The high harmonic generation process, which is typically the result of strong field interaction of noble gases with an intense low-frequency pulse,
* Attosecond pump-probe experiments with simple atoms.
* The debate on tunneling time. | 0 | Theoretical and Fundamental Chemistry |
The mass of an atomic nucleus, for neutrons, protons, and therefore nucleons, is given by
where and are the rest mass of a proton and a neutron respectively, and is the binding energy of the nucleus. The semi-empirical mass formula states the binding energy is
The term is either zero or , depending on the parity of and , where for some exponent . Note that as , the numerator of the term can be rewritten as .
Each of the terms in this formula has a theoretical basis. The coefficients , , , , and are determined empirically; while they may be derived from experiment, they are typically derived from least-squares fit to contemporary data. While typically expressed by its basic five terms, further terms exist to explain additional phenomena. Akin to how changing a polynomial fit will change its coefficients, the interplay between these coefficients as new phenomena are introduced is complex; some terms influence each other, whereas the term is largely independent. | 0 | Theoretical and Fundamental Chemistry |
A dangling side chain is a hydrocarbon chain side chains that branch off of the backbone of the polymer. Attached to the side chain are polar functional groups. The side chains "dangle" across the surface of the hydrogel, allowing it to interact with other functional groups and form new bonds. The ideal side chain would be long and flexible so it could reach across the surface to react, but short enough to minimize steric hindrance and collapse from the hydrophobic effect. The side chains need to keep both the hydrophobic and hydrophilic effects in balance. In a study performed by the University of California San Diego to compare healing ability, hydrogels of varying side chain lengths with similar crosslinking contents were compared and the results showed that healing ability of the hydrogels depends nonmonotonically on the side chain length. With shorter side chain lengths, there is limited reach of the carboxyl group which decreases the mediation of the hydrogen bonds across the interface. As the chain increases in length, the reach of the carboxyl group becomes more flexible and the hydrogen bonds can mediated. However, when a side chain length is too long, the interruption between the interaction of the carboxyl and amide groups that help to mediate the hydrogen bonds. It can also accumulate and collapse the hydrogel and prevent the healing from occurring. | 0 | Theoretical and Fundamental Chemistry |
Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane, controlling the flow of ions across secretory and epithelial cells, and regulating cell volume. Ion channels are present in the membranes of all cells. Ion channels are one of the two classes of ionophoric proteins, the other being ion transporters.
The study of ion channels often involves biophysics, electrophysiology, and pharmacology, while using techniques including voltage clamp, patch clamp, immunohistochemistry, X-ray crystallography, fluoroscopy, and RT-PCR. Their classification as molecules is referred to as channelomics. | 1 | Applied and Interdisciplinary Chemistry |
Oxidation of pyridine occurs at nitrogen to give pyridine N-oxide. The oxidation can be achieved with peracids:
:CHN + RCOH → CHNO + RCOH
Some electrophilic substitutions on the pyridine are usefully effected using pyridine N-oxide followed by deoxygenation. Addition of oxygen suppresses further reactions at nitrogen atom and promotes substitution at the 2- and 4-carbons. The oxygen atom can then be removed, e.g., using zinc dust. | 0 | Theoretical and Fundamental Chemistry |
α-Naphtholphthalein (CHO) is a phthalein dye used as a pH indicator with a visual transition from colorless/reddish to greenish blue at pH 7.3–8.7. | 0 | Theoretical and Fundamental Chemistry |
Oocyte selection is a procedure that is performed prior to in vitro fertilization, in order to use oocytes with maximal chances of resulting in pregnancy. In contrast, embryo selection takes place after fertilization.
Not all women can conceive naturally, leaving them with a need for technologies and research that can help them have children. Women who might not be able to have their kids naturally may have the option of in vitro fertilization. In vitro fertilization can be a series of treatments that involves the fertilization of a mature egg with a sperm in a laboratory. Oocyte selection is a part the process for in vitro fertilization. An Oocyte is an egg/ovum that is not fully mature or developed and has not been fertilized; Therefore an oocyte is an undeveloped ovum.
__TOC__ | 1 | Applied and Interdisciplinary Chemistry |
Equilibrium fractionation occurs between chemicals or phases that are in equilibrium with each other. In equilibrium fractionation between phases, heavier phases prefer the heavier isotopes. For two phases A and B, the effect can be represented by the factor
In the liquid-vapor phase transition for water, at 20 degrees Celsius is 1.0098 for O and 1.084 for H. In general, fractionation is greater at lower temperatures. At 0 °C, the factors are 1.0117 and 1.111. | 0 | Theoretical and Fundamental Chemistry |
A significant feature of the Cauchy equation and consequently all other continuum equations (including Euler and Navier–Stokes) is the presence of convective acceleration: the effect of acceleration of a flow with respect to space. While individual fluid particles indeed experience time-dependent acceleration, the convective acceleration of the flow field is a spatial effect, one example being fluid speeding up in a nozzle. | 1 | Applied and Interdisciplinary Chemistry |
Ethyl cyanohydroxyiminoacetate is a white solid which is soluble in many solvents common in the synthesis of peptides, such as dichloromethane or dimethylformamide (DMF). In crystalline form, the compound is present as an oxime, whereas it exists as a salt or in a strongly basic solution predominantly as a tautomeric nitrosoisomer in anionic form. | 0 | Theoretical and Fundamental Chemistry |
Haloalkanes are diverse in their properties, making generalizations difficult. Few are acutely toxic, but many pose risks from prolonged exposure. Some problematic aspects include carcinogenicity and liver damage (e.g., carbon tetrachloride). Under certain combustion conditions, chloromethanes convert to phosgene, which is highly toxic. | 1 | Applied and Interdisciplinary Chemistry |
The details of an agarose gel electrophoresis experiment may vary depending on methods, but most follow a general procedure. | 1 | Applied and Interdisciplinary Chemistry |
The Coandă effect, also known as "boundary layer attachment", is the tendency of a moving fluid to adhere to an adjacent wall. | 1 | Applied and Interdisciplinary Chemistry |
Fluorescence is when a molecule emits light of one wavelength after absorbing light of a different wavelength. Fluorometric assays use a difference in the fluorescence of substrate from product to measure the enzyme reaction. These assays are in general much more sensitive than spectrophotometric assays, but can suffer from interference caused by impurities and the instability of many fluorescent compounds when exposed to light.
An example of these assays is again the use of the nucleotide coenzymes NADH and NADPH. Here, the reduced forms are fluorescent and the oxidised forms non-fluorescent. Oxidation reactions can therefore be followed by a decrease in fluorescence and reduction reactions by an increase. Synthetic substrates that release a fluorescent dye in an enzyme-catalyzed reaction are also available, such as 4-methylumbelliferyl-β-D-galactoside for assaying β-galactosidase or 4-methylumbelliferyl-butyrate for assaying Candida rugosa lipase. | 1 | Applied and Interdisciplinary Chemistry |
Photobiologically Active Radiation (PBAR) is a range of light energy beyond and including PAR. Photobiological Photon Flux (PBF) is the metric used to measure PBAR. | 0 | Theoretical and Fundamental Chemistry |
Front-of-house testing provides testing services to clients at events. It provides real-time, as-you-wait results. An example is the testing at BOOM festival in Portugal where drug testers are legally allowed to handle samples. Where testers are not allowed to handle samples, for fear of breaking laws around possession, clients themselves must handle the substance to be tested. Examples of this model are KnowYourStuffNZ in New Zealand. | 0 | Theoretical and Fundamental Chemistry |
The Joint Center for Artificial Photosynthesis (JCAP), founded in 2010, is a (DOE) Energy Innovation Hub whose primary mission is to find a cost-effective method to produce fuels using only sunlight, water, and carbon-dioxide. The program has a budget of $122M over five years, subject to Congressional appropriation.
The Director of JCAP is Professor Harry Atwater of Caltech and its two main centers are located at the California Institute of Technology and the Lawrence Berkeley National Laboratory. In addition, JCAP has partners from Stanford University, the University of California at Berkeley, University of California at Santa Barbara, University of California at Irvine, the University of California at San Diego, and Stanford Linear Accelerator. In addition, JCAP also serves as a hub for other solar fuels research teams across the United States, including 20 DOE Energy Frontier Research Center.
In Obamas 2011 State of the Union address, he mentioned the Joint Center for Artificial Photosynthesis. Specifically, he said, "Were issuing a challenge. Were telling Americas scientists and engineers that if they assemble teams of the best minds in their fields, and focus on the hardest problems in clean energy, well fund the Apollo projects of our time. At the California Institute of Technology, theyre developing a way to turn sunlight and water into fuel for our cars". | 0 | Theoretical and Fundamental Chemistry |
The episodes "The Naked Time" (Star Trek, 1966) and its sequel, "The Naked Now" (Star Trek: The Next Generation, 1987) involve forms of polywater intoxication. In the original episode, a scientific research outpost falls victim to polywater, which causes the crew to become so incapacitated that they all died after shutting off environmental controls in the compound. In the sequel, a Starfleet vessel is discovered adrift, its crew frozen in various states due to polywater intoxication.
The story "Polywater Doodle" by Howard L. Myers (writing under the pseudonym "Dr. Dolittle") appeared in the February 1971 issue of Analog Science Fiction and Fact. It features an animal composed entirely of polywater, with the metabolism described by Richard Feynman. (The title of the story is a pun on "Polly Wolly Doodle".)
Polywater is the central idea of the 1972 espionage/thriller novel A Report from Group 17 by Robert C. O'Brien. The story revolves around the use of a type of polywater to make people controllable and incapable of independent thought or action. | 1 | Applied and Interdisciplinary Chemistry |
There are many ways to help fix cultural eutrophication caused by agriculture. Some recommendations issued by the U.S. Department of Agriculture:
# Nutrient Management Techniques - Anyone using fertilizers should apply fertilizer in the correct amount, at the right time of year, with the right method and placement. Organically fertilized fields can "significantly reduce harmful nitrate leaching" compared to conventionally fertilized fields. Eutrophication impacts are in some cases higher from organic production than they are from conventional production. In Japan the amount of nitrogen produced by livestock is adequate to serve the fertilizer needs for the agriculture industry.
# Year - Round Ground Cover - a cover crop will prevent periods of bare ground thus eliminating erosion and runoff of nutrients even after the growing season has occurred.
# Planting Field Buffers - By planting trees, shrubs and grasses along the edges of fields to help catch the runoff and absorb some nutrients before the water makes it to a nearby water body. Riparian buffer zones are interfaces between a flowing body of water and land, and have been created near waterways in an attempt to filter pollutants; sediment and nutrients are deposited here instead of in water. Creating buffer zones near farms and roads is another possible way to prevent nutrients from traveling too far. Still, studies have shown that the effects of atmospheric nitrogen pollution can reach far past the buffer zone. This suggests that the most effective means of prevention is from the primary source.
# Conservation Tillage - By reducing frequency and intensity of tilling the land will enhance the chance of nutrients absorbing into the ground. | 1 | Applied and Interdisciplinary Chemistry |
While some chemotaxis receptors are expressed in the surface membrane with long-term characteristics, as they are determined genetically, others have short-term dynamics, as they are assembled ad hoc in the presence of the ligand. The diverse features of the chemotaxis receptors and ligands allows for the possibility of selecting chemotactic responder cells with a simple chemotaxis assay By chemotactic selection, we can determine whether a still-uncharacterized molecule acts via the long- or the short-term receptor pathway. The term chemotactic selection is also used to designate a technique that separates eukaryotic or prokaryotic cells according to their chemotactic responsiveness to selector ligands. | 1 | Applied and Interdisciplinary Chemistry |
The inner chloroplast membrane borders the stroma and regulates passage of materials in and out of the chloroplast. After passing through the TOC complex in the outer chloroplast membrane, polypeptides must pass through the TIC complex (translocon on the inner chloroplast membrane) which is located in the inner chloroplast membrane.
In addition to regulating the passage of materials, the inner chloroplast membrane is where fatty acids, lipids, and carotenoids are synthesized. | 0 | Theoretical and Fundamental Chemistry |
PIPES (piperazine-N,N-bis(2-ethanesulfonic acid)) is a frequently used buffering agent in biochemistry. It is an ethanesulfonic acid buffer developed by Good et al. in the 1960s. | 1 | Applied and Interdisciplinary Chemistry |
In the absence of adequate cooling, the materials inside of the reactor vessel overheat and deform as they undergo thermal expansion, and the reactor structure fails once the temperature reaches the melting point of its structural materials. The corium melt then accumulates at the bottom of the reactor vessel. In the case of adequate cooling of the corium, it can solidify and the damage is limited to the reactor itself. Corium may also melt through the reactor vessel and flow out or be ejected as a molten stream by the pressure inside the reactor vessel. The reactor vessel failure may be caused by heating of its vessel bottom by the corium, resulting first in creep failure and then in breach of the vessel. Cooling water from above the corium layer, in sufficient quantity, may obtain a thermal equilibrium below the metal creep temperature, without reactor vessel failure.
If the vessel is sufficiently cooled, a crust between the corium melt and the reactor wall can form. The layer of molten steel at the top of the oxide may create a zone of increased heat transfer to the reactor wall; this condition, known as "heat knife", increases the probability of formation of a localized weakening of the side of the reactor vessel and subsequent corium leak.
In the case of high pressure inside the reactor vessel, breaching of its bottom may result in high-pressure blowout of the corium mass. In the first phase, only the melt itself is ejected; later a depression may form in the center of the hole and gas is discharged together with the melt with a rapid decrease of pressure inside the reactor vessel; the high temperature of the melt also causes rapid erosion and enlargement of the vessel breach. If the hole is in the center of the bottom, nearly all corium can be ejected. A hole in the side of the vessel may lead to only partial ejection of corium, with a retained portion left inside the reactor vessel.
Melt-through of the reactor vessel may take from a few tens of minutes to several hours.
After breaching the reactor vessel, the conditions in the reactor cavity below the core govern the subsequent production of gases. If water is present, steam and hydrogen are generated; dry concrete results in production of carbon dioxide and smaller amount of steam. | 0 | Theoretical and Fundamental Chemistry |
The phenomenon is so named after the lead researchers from a joint team drawn from NASA Ames Research Center, the Field Artillery Training Center at Fort Sill, Oklahoma and instructors from the USAF Air Weapons School at Nellis AFB in response to a formal request for assistance from United States Central Command, MacDill AFB, Tampa, Florida, framed following events during Operation Anaconda. Instructors from the Royal School of Artillery's Gunnery Training Team also assisted. | 1 | Applied and Interdisciplinary Chemistry |
In physics, a bipolaron is a type of quasiparticle consisting of two polarons. In organic chemistry, it is a molecule or a part of a macromolecular chain containing two positive charges in a conjugated system. | 0 | Theoretical and Fundamental Chemistry |
Both the fluorescence excitation and emission spectrums of wild-type EosFP are shifted ~65 nm to the right upon excitation toward the red end of the spectrum. This spectral change is caused by an extension of the chromophore accompanied by a break in the peptide backbone between Phe-61 and His-62 in an irreversible mechanism. The presence of a crisp isosbestic point at 432 nm also suggests an interconversion between two species. An absorption peak at 280 nm is visible due to aromatic amino acids which transfer their excitation energy to the green chromophore. The quantum yield of the green-emitting form of Eos is 0.7. In the red shifted species, there are pronounced vibronic sidebands separate from the main peak at 533 nm and 629 nm in the excitation spectrum and emission spectrum respectively. There is another peak in the red excitation spectrum at 502 nm likely due to FRET excitation of the red fluorophore. The quantum yield of the red-emitting form is 0.55.
EosFPs variants show almost no difference in spectroscopic properties, therefore, it is likely that the structural modifications which arise from separation of interfaces have little to no effect on the structure of the fluorophore-binding site. | 1 | Applied and Interdisciplinary Chemistry |
Metal oxide varistors typically develop lower resistance as they heat up. If connected directly across an AC or DC power bus (a common usage for protection against voltage spikes), a MOV which has developed a lowered trigger voltage can slide into catastrophic thermal runaway, possibly culminating in a small explosion or fire. To prevent this possibility, fault current is typically limited by a thermal fuse, circuit breaker, or other current limiting device. | 1 | Applied and Interdisciplinary Chemistry |
In the process of smelting, inorganic chlorides, fluorides (see fluorite), limestone and other materials are designated as "fluxes" when added to the contents of a smelting furnace or a cupola for the purpose of purging the metal of chemical impurities such as phosphorus, and of rendering slag more liquid at the smelting temperature. Slag is a liquid mixture of ash, flux, and other impurities. This reduction of slag viscosity with temperature, increasing the flow of slag in smelting, is the origin of the word flux in metallurgy.
The flux most commonly used in iron and steel furnaces is limestone, which is charged in the proper proportions with the iron and fuel. | 1 | Applied and Interdisciplinary Chemistry |
The detection of -2-hydroxyglutarate in glioma patients using proton magnetic resonance spectroscopy (MRS) has been shown to be a noninvasive procedure. The presence of IDH1 or IDH2 mutations was linked to the detection of this oncometabolite 100 percent of the time. IDH2/R140Q is a specific mutation that has shown promising results after its inhibition by the small molecule AGI-6780. Therefore, limiting the supply of -2-hydroxyglutarate by inhibiting the detected mutant IDH enzymes could be a good therapeutical approach to IDH-mutant cancers. | 1 | Applied and Interdisciplinary Chemistry |
The Super-Kamiokande is a 50,000 ton water Cherenkov detector underground. The primary uses for this detector in Japan in addition to neutrino observation is cosmic ray observation as well as searching for proton decay. In 1998, the Super-Kamiokande was the site of the Super-Kamiokande experiment which led to the discovery of neutrino oscillation, the process by neutrinos change their flavor, either to electron, muon or tau.
The Super-Kamiokande experiment began in 1996 and is still active. In the experiment, the detector works by being able to spot neutrinos by analyzing water molecules and detecting electrons being removed from them which then produces a blue Cherenkov light, which is produced by neutrinos. Therefore, when this detection of blue light happens it can be inferred that a neutrino is present and counted. | 0 | Theoretical and Fundamental Chemistry |
An extensive range of recommended values for the Margules parameters can be found in the literature. Selected values are provided in the table below. | 0 | Theoretical and Fundamental Chemistry |
The Lifshitz theory can be expressed as an effective Hamaker constant in the van der Waals theory.
Consider, for example, the interaction between an ion of charge , and a nonpolar molecule with polarizability at distance . In a medium with dielectric constant , the interaction energy between a charge and an electric dipole is given by
with the dipole moment of the polarizable molecule given by , where is the strength of the electric field at distance from the ion. According to Coulomb's law:
so we may write the interaction energy as
Consider now, how the interaction energy will change if the right hand molecule is replaced with a medium of density of such molecules. According to the "classical" van der Waals theory, the total force will simply be the summation over individual molecules. Integrating over the volume of the medium (see the third figure), we might expect the total interaction energy with the charge to be
But this result cannot be correct, since It is well known that a charge in a medium of dielectric constant at a distance from the plane surface of a second medium of dielectric constant experiences a force as if there were an image charge of strength at distance D on the other side of the boundary. The force between the real and image charges must then be
and the energy, therefore
Equating the two expressions for the energy, we define a new effective polarizability that must obey
Similarly, replacing the real charge with a medium of density and polarizability gives an expression for . Using these two relations, we may restate our theory in terms of an effective Hamaker constant. Specifically, using McLachlan's generalized theory of VDW forces the Hamaker constant for an interaction potential of the form between two bodies at temperature is
with , where and are Boltzmanns and Plancks constants correspondingly. Inserting our relations for and approximating the sum as an integral , the effective Hamaker constant in the Lifshitz theory may be approximated as
We note that are real functions, and are related to measurable properties of the medium; thus, the Hamaker constant in the Lifshitz theory can be expressed in terms of observable properties of the physical system. | 0 | Theoretical and Fundamental Chemistry |
According to Zang, numerical simulation can be aided by considering the skew-symmetric form for the advection operator.
where
and is the same as above.
Since skew symmetry implies only imaginary eigenvalues, this form reduces the "blow up" and "spectral blocking" often experienced in numerical solutions with sharp discontinuities.
Using vector calculus identities, these operators can also be expressed in other ways, available in more software packages for more coordinate systems.
This form also makes visible that the skew-symmetric operator introduces error when the velocity field diverges. Solving the advection equation by numerical methods is very challenging and there is a large scientific literature about this. | 1 | Applied and Interdisciplinary Chemistry |
*X-ray crystallography
Just like other organic molecule study, X-ray crystallography is a very useful tool to know the detail information on the interaction between carbohydrate and protein.
*NMR Study
By using titration, NOESY(Nuclear Overhauser Effect SpectroscopY), CIDNP experiments, the specificity and affinity of binding, association constants and equilibrium thermodynamic parameters of carbohydrate–protein binding can be studied.
*Molecular Modeling
In many cases, the conformation information is required, however, sometimes it is not able to get directly from the experiments. So the knowledge-based model building approach is used.
*Fluorescence Spectrometry
Fluorescence spectrometry is a useful tool and has its advantages: no procedure for separation and plenty of ways to get fluorophore source: there are some of amino acids and ligands that have fluorophore after they are activated.
*Dual polarisation interferometry
Dual polarisation interferometry is a label free analytical technique for measuring interactions and associated conformational changes. | 0 | Theoretical and Fundamental Chemistry |
Togni reagent II is used for trifluoromethylation of organic compounds. For phenolates, the substitution takes place preferably in the ortho position. It is possible to obtain a second substitution by using an excess of Togni reagent II.
Reactions with alcohols yield the corresponding trifluoromethyl ethers.
Trifluoromethylation of alkenes is possible under copper catalysis. | 0 | Theoretical and Fundamental Chemistry |
Sequencing of nearly an entire human genome was first accomplished in 2000 partly through the use of shotgun sequencing technology. While full genome shotgun sequencing for small (4000–7000 base pair) genomes was already in use in 1979, broader application benefited from pairwise end sequencing, known colloquially as double-barrel shotgun sequencing. As sequencing projects began to take on longer and more complicated genomes, multiple groups began to realize that useful information could be obtained by sequencing both ends of a fragment of DNA. Although sequencing both ends of the same fragment and keeping track of the paired data was more cumbersome than sequencing a single end of two distinct fragments, the knowledge that the two sequences were oriented in opposite directions and were about the length of a fragment apart from each other was valuable in reconstructing the sequence of the original target fragment.
The first published description of the use of paired ends was in 1990 as part of the sequencing of the human HPRT locus, although the use of paired ends was limited to closing gaps after the application of a traditional shotgun sequencing approach. The first theoretical description of a pure pairwise end sequencing strategy, assuming fragments of constant length, was in 1991. In 1995 the innovation of using fragments of varying sizes was introduced, and demonstrated that a pure pairwise end-sequencing strategy would be possible on large targets. The strategy was subsequently adopted by The Institute for Genomic Research (TIGR) to sequence the entire genome of the bacterium Haemophilus influenzae in 1995, and then by Celera Genomics to sequence the entire fruit fly genome in 2000, and subsequently the entire human genome. Applied Biosystems, now called Life Technologies, manufactured the automated capillary sequencers utilized by both Celera Genomics and The Human Genome Project. | 1 | Applied and Interdisciplinary Chemistry |
Slayton A. Evans Jr. (May 17, 1943 – March 24, 2001) was an American chemist and professor at the University of North Carolina, Chapel Hill. He was a leading researcher into organophosphorus chemistry. His research led to a greater understanding of the functions of organophosphate compounds and innovations in methods to produce chemical compounds for pharmaceutical drugs. | 0 | Theoretical and Fundamental Chemistry |
A weak electrolyte is one that is never fully dissociated (there are a mixture of ions and complete molecules in equilibrium). In this case there is no limit of dilution below which the relationship between conductivity and concentration becomes linear. Instead, the solution becomes ever more fully dissociated at weaker concentrations, and for low concentrations of "well behaved" weak electrolytes, the degree of dissociation of the weak electrolyte becomes proportional to the inverse square root of the concentration.
Typical weak electrolytes are weak acids and weak bases. The concentration of ions in a solution of a weak electrolyte is less than the concentration of the electrolyte itself. For acids and bases the concentrations can be calculated when the value or values of the acid dissociation constant are known.
For a monoprotic acid, HA, obeying the inverse square root law, with a dissociation constant , an explicit expression for the conductivity as a function of concentration, , known as Ostwald's dilution law, can be obtained.
Various solvents exhibit the same dissociation if the ratio of relative permittivities equals the ratio cubic roots of concentrations of the electrolytes (Walden's rule). | 0 | Theoretical and Fundamental Chemistry |
In mass spectrometry, an ion funnel is a device used to focus a beam of ions using a series of stacked ring electrodes with decreasing inner diameter. A combined radio frequency and fixed electrical potential is applied to the grids. In electrospray ionization-mass spectrometry (ESI-MS), ions are created at atmospheric pressure, but are analyzed at subsequently lower pressures. Ions can be lost while they are shuttled from areas of higher to lower pressure due to the transmission process caused by a phenomenon called joule expansion or “free-jet expansion.” These ion clouds expand outward, which limits the amount of ions that reach the detector, so fewer ions are analyzed. The ion funnel refocuses and transmits ions efficiently from those areas of high to low pressure. | 0 | Theoretical and Fundamental Chemistry |
X-ray photoelectron spectroscopy (XPS) and Energy-dispersive X-ray spectroscopy (EDS/EDX) are composition characterization techniques that use x-ray excitation of electrons to discrete energy levels to quantify chemical composition. These techniques provide characterization at surface depths of 1–10 nanometers, approximately the range of oxidation in plasma and corona treatments. In addition, these processes offer the benefit of characterizing microscopic variations in surface composition.
In the context of plasma processed polymer surfaces, oxidized surfaces will obviously show a greater oxygen content. Elemental analysis allows for quantitative data to be obtained and used in the analysis of process efficiency. | 0 | Theoretical and Fundamental Chemistry |
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