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The National Center for Functional Glycomics has developed GlycoPattern, a web-based bioinformatics resource to assist in analysis of glycan array data. The GlycoPattern website offers tools and algorithms to discover structural motifs, heatmap visualizations for multiple experiment comparisons, clustering of Glycan Binding Proteins. | 0 | Theoretical and Fundamental Chemistry |
The development of chemoenzymatic strategies to generate large libraries of non-native sugar nucleotides has enabled a process referred to as glycorandomization where these sugar nucleotide libraries serve as donors for permissive glycosyltransferases to afford differential glycosylation of a wide range of pharmaceuticals and complex natural product-based leads. | 0 | Theoretical and Fundamental Chemistry |
The first on-line coupling of gas chromatography to a mass spectrometer was reported in the late 1950s. An interest in coupling the methods had been suggested as early as December 1954.
The development of affordable and miniaturized computers has helped in the simplification of the use of this instrument, as well as allowed great improvements in the amount of time it takes to analyze a sample. In 1964, Electronic Associates, Inc. (EAI), a leading U.S. supplier of analog computers, began development of a computer controlled quadrupole mass spectrometer under the direction of Robert E. Finnigan. By 1966 Finnigan and collaborator Mike Uthes EAI division had sold over 500 quadrupole residual gas-analyzer instruments. In 1967, Finnigan left EAI to form the Finnigan Instrument Corporation along with Roger Sant, T. Z. Chou, Michael Story, Lloyd Friedman, and William Fies. In early 1968, they delivered the first prototype quadrupole GC/MS instruments to Stanford and Purdue University. When Finnigan Instrument Corporation was acquired by Thermo Instrument Systems (later Thermo Fisher Scientific) in 1990, it was considered "the worlds leading manufacturer of mass spectrometers". | 0 | Theoretical and Fundamental Chemistry |
A third confinement principle is to apply a rapid pulse of energy to a large part of the surface of a pellet of fusion fuel, causing it to simultaneously "implode" and heat to very high pressure and temperature. If the fuel is dense enough and hot enough, the fusion reaction rate will be high enough to burn a significant fraction of the fuel before it has dissipated. To achieve these extreme conditions, the initially cold fuel must be explosively compressed. Inertial confinement is used in the hydrogen bomb, where the driver is x-rays created by a fission bomb. Inertial confinement is also attempted in "controlled" nuclear fusion, where the driver is a laser, ion, or electron beam, or a Z-pinch. Another method is to use conventional high explosive material to compress a fuel to fusion conditions. The UTIAS explosive-driven-implosion facility was used to produce stable, centred and focused hemispherical implosions to generate neutrons from D-D reactions. The simplest and most direct method proved to be in a predetonated stoichiometric mixture of deuterium-oxygen. The other successful method was using a miniature Voitenko compressor, where a plane diaphragm was driven by the implosion wave into a secondary small spherical cavity that contained pure deuterium gas at one atmosphere. | 0 | Theoretical and Fundamental Chemistry |
Portland cement is approximately two-thirds calcium oxide by mass and its manufacture is responsible for approximately 8% of the world's CO emissions. 60% of this CO comes from the calcination of calcium carbonate as shown earlier in this article, and the other 40% from fossil fuel combustion. By replacing some or all of the calcium carbonate entering the plant with waste calcium oxide, the CO caused from calcination can be avoided, as well as some of the CO from fossil fuel combustion.
This calcium oxide could be sourced from other point sources of CO such as power stations, but most effort has been focussed on integrating calcium looping with Portland cement manufacture. By replacing the calciner in the cement plant with a calcium looping plant, it should be possible to capture 90% or more of the CO relatively inexpensively. There are alternative set-ups such as placing the calcium looping plant in the preheater section so as to make the plant as efficient as possible.
Some work has been undertaken into whether calcium looping affects the quality of the Portland cement produced, but results so far seem to suggest that the production of strength-giving phases such as alite are similar for calcium looped and non-calcium looped cement. | 1 | Applied and Interdisciplinary Chemistry |
The liquidus temperature has been modeled by non-linear regression using neural networks and disconnected peak functions. The disconnected peak functions approach is based on the observation that within one primary crystalline phase field linear regression can be applied and at eutectic points sudden changes occur. | 0 | Theoretical and Fundamental Chemistry |
The technique for RFLP analysis is, however, slow and cumbersome. It requires a large amount of sample DNA, and the combined process of probe labeling, DNA fragmentation, electrophoresis, blotting, hybridization, washing, and autoradiography can take up to a month to complete. A limited version of the RFLP method that used oligonucleotide probes was reported in 1985. The results of the Human Genome Project have largely replaced the need for RFLP mapping, and the identification of many single-nucleotide polymorphisms (SNPs) in that project (as well as the direct identification of many disease genes and mutations) has replaced the need for RFLP disease linkage analysis (see SNP genotyping). The analysis of VNTR alleles continues, but is now usually performed by polymerase chain reaction (PCR) methods. For example, the standard protocols for DNA fingerprinting involve PCR analysis of panels of more than a dozen VNTRs.
RFLP is still used in marker-assisted selection. Terminal restriction fragment length polymorphism (TRFLP or sometimes T-RFLP) is a technique initially developed for characterizing bacterial communities in mixed-species samples. The technique has also been applied to other groups including soil fungi. TRFLP works by PCR amplification of DNA using primer pairs that have been labeled with fluorescent tags. The PCR products are then digested using RFLP enzymes and the resulting patterns visualized using a DNA sequencer. The results are analyzed either by simply counting and comparing bands or peaks in the TRFLP profile, or by matching bands from one or more TRFLP runs to a database of known species. A number of different software tools have been developed to automate the process of band matching, comparison and data basing of TRFLP profiles.
The technique is similar in some aspects to temperature gradient or denaturing gradient gel electrophoresis (TGGE and DGGE).
The sequence changes directly involved with an RFLP can also be analyzed more quickly by PCR. Amplification can be directed across the altered restriction site, and the products digested with the restriction enzyme. This method has been called Cleaved Amplified Polymorphic Sequence (CAPS). Alternatively, the amplified segment can be analyzed by allele-specific oligonucleotide (ASO) probes, a process that can often be done by a simple dot blot. | 1 | Applied and Interdisciplinary Chemistry |
* CDC14s: CDC14A, CDC14B, CDC14C, CDKN3
* Phosphatase and tensin homologs: PTEN
* slingshot: SSH1, SSH2, SSH3 | 1 | Applied and Interdisciplinary Chemistry |
Fluid–structure interactions are a crucial consideration in the design of many engineering systems, e.g. automobile, aircraft, spacecraft, engines and bridges. Failing to consider the effects of oscillatory interactions can be catastrophic, especially in structures comprising materials susceptible to fatigue. Tacoma Narrows Bridge (1940), the first Tacoma Narrows Bridge, is probably one of the most infamous examples of large-scale failure. Aircraft wings and turbine blades can break due to FSI oscillations. A reed actually produces sound because the system of equations governing its dynamics has oscillatory solutions. The dynamic of reed valves used in two strokes engines and compressors is governed by FSI. The act of "blowing a raspberry" is another such example. The interaction between tribological machine components, such as bearings and gears, and lubricant is also an example of FSI. The lubricant flows between the contacting solid components and causes elastic deformation in them during this process. Fluid–structure interactions also occur in moving containers, where liquid oscillations due to the container motion impose substantial magnitudes of forces and moments to the container structure that affect the stability of the container transport system in a highly adverse manner. Another prominent example is the start up of a rocket engine, e.g. Space Shuttle main engine (SSME), where FSI can lead to considerable unsteady side loads on the nozzle structure. In addition to pressure-driven effects, FSI can also have a large influence on surface temperatures on supersonic and hypersonic vehicles.
Fluid–structure interactions also play a major role in appropriate modeling of blood flow. Blood vessels act as compliant tubes that change size dynamically when there are changes to blood pressure and velocity of flow. Failure to take into account this property of blood vessels can lead to a significant overestimation of resulting wall shear stress (WSS). This effect is especially imperative to take into account when analyzing aneurysms. It has become common practice to use computational fluid dynamics to analyze patient specific models. The neck of an aneurysm is the most susceptible to changes in to WSS. If the aneurysmal wall becomes weak enough, it becomes at risk of rupturing when WSS becomes too high. FSI models contain an overall lower WSS compared to non-compliant models. This is significant because incorrect modeling of aneurysms could lead to doctors deciding to perform invasive surgery on patients who were not at a high risk of rupture. While FSI offers better analysis, it comes at a cost of highly increased computational time. Non-compliant models have a computational time of a few hours, while FSI models could take up to 7 days to finish running. This leads to FSI models to be most useful for preventative measures for aneurysms caught early, but unusable for emergency situations where the aneurysm may have already ruptured. | 1 | Applied and Interdisciplinary Chemistry |
There are two main considerations for the location of an explosion: height and surface composition. A nuclear weapon detonated in the air, called an air burst, produces less fallout than a comparable explosion near the ground. A nuclear explosion in which the fireball touches the ground pulls soil and other materials into the cloud and neutron activates it before it falls back to the ground. An air burst produces a relatively small amount of the highly radioactive heavy metal components of the device itself.
In case of water surface bursts, the particles tend to be rather lighter and smaller, producing less local fallout but extending over a greater area. The particles contain mostly sea salts with some water; these can have a cloud seeding effect causing local rainout and areas of high local fallout. Fallout from a seawater burst is difficult to remove once it has soaked into porous surfaces because the fission products are present as metallic ions that chemically bond to many surfaces. Water and detergent washing effectively removes less than 50% of this chemically bonded activity from concrete or steel. Complete decontamination requires aggressive treatment like sandblasting, or acidic treatment. After the Crossroads underwater test, it was found that wet fallout must be immediately removed from ships by continuous water washdown (such as from the fire sprinkler system on the decks).
Parts of the sea bottom may become fallout. After the Castle Bravo test, white dust—contaminated calcium oxide particles originating from pulverized and calcined corals—fell for several hours, causing beta burns and radiation exposure to the inhabitants of the nearby atolls and the crew of the Daigo Fukuryū Maru fishing boat. The scientists called the fallout Bikini snow.
For subsurface bursts, there is an additional phenomenon present called "base surge". The base surge is a cloud that rolls outward from the bottom of the subsiding column, which is caused by an excessive density of dust or water droplets in the air. For underwater bursts, the visible surge is, in effect, a cloud of liquid (usually water) droplets with the property of flowing almost as if it were a homogeneous fluid. After the water evaporates, an invisible base surge of small radioactive particles may persist.
For subsurface land bursts, the surge is made up of small solid particles, but it still behaves like a fluid. A soil earth medium favors base surge formation in an underground burst. Although the base surge typically contains only about 10% of the total bomb debris in a subsurface burst, it can create larger radiation doses than fallout near the detonation, because it arrives sooner than fallout, before much radioactive decay has occurred. | 0 | Theoretical and Fundamental Chemistry |
Dr. Chris Ballentine is the chair of geochemistry and head of the Department of Earth Sciences at the University of Oxford, in the United Kingdom. He uses properties of the noble gases to understand the origin and evolution of Earth's atmosphere and mantle. | 0 | Theoretical and Fundamental Chemistry |
In mammals, microRNAs (miRNAs) regulate the transcriptional activity of about 60% of protein-encoding genes. Individual miRNAs can each target, and repress transcription of, on average, roughly 200 messenger RNAs of protein coding genes. The promoters of about one third of the 167 miRNAs evaluated by Vrba et al. in normal breast tissues were differentially hyper/hypo-methylated in breast cancers. A more recent study pointed out that the 167 miRNAs evaluated by Vrba et al. were only 10% of the miRNAs found expressed in breast tissues. This later study found that 58% of the miRNAs in breast tissue had differentially methylated regions in their promoters in breast cancers, including 278 hypermethylated miRNAs and 802 hypomethylated miRNAs.
One miRNA that is over-expressed about 100-fold in breast cancers is miR-182. MiR-182 targets the BRCA1 messenger RNA and may be a major cause of reduced BRCA1 protein expression in many breast cancers (also see BRCA1). | 1 | Applied and Interdisciplinary Chemistry |
In renal physiology, the glomerular sieving coefficient (GSC) can be expressed as:
sieving coefficient = clearance / ultrafiltration rate | 1 | Applied and Interdisciplinary Chemistry |
In the field of physics, engineering, and earth sciences, advection is the transport of a substance or quantity by bulk motion of a fluid. The properties of that substance are carried with it. Generally the majority of the advected substance is also a fluid. The properties that are carried with the advected substance are conserved properties such as energy. An example of advection is the transport of pollutants or silt in a river by bulk water flow downstream. Another commonly advected quantity is energy or enthalpy. Here the fluid may be any material that contains thermal energy, such as water or air. In general, any substance or conserved, extensive quantity can be advected by a fluid that can hold or contain the quantity or substance.
During advection, a fluid transports some conserved quantity or material via bulk motion. The fluid's motion is described mathematically as a vector field, and the transported material is described by a scalar field showing its distribution over space. Advection requires currents in the fluid, and so cannot happen in rigid solids. It does not include transport of substances by molecular diffusion.
Advection is sometimes confused with the more encompassing process of convection, which is the combination of advective transport and diffusive transport.
In meteorology and physical oceanography, advection often refers to the transport of some property of the atmosphere or ocean, such as heat, humidity (see moisture) or salinity.
Advection is important for the formation of orographic clouds and the precipitation of water from clouds, as part of the hydrological cycle. | 1 | Applied and Interdisciplinary Chemistry |
The experimental procedure first requires a sample of purified plasmid DNA for each digest to be run. Digestion is then performed with each enzyme(s) chosen. The resulting samples are subsequently run on an electrophoresis gel, typically on agarose gel.
The first step following the completion of electrophoresis is to add up the sizes of the fragments in each lane. The sum of the individual fragments should equal the size of the original fragment, and each digest's fragments should also sum up to be the same size as each other. If fragment sizes do not properly add up, there are two likely problems. In one case, some of the smaller fragments may have run off the end of the gel. This frequently occurs if the gel is run too long. A second possible source of error is that the gel was not dense enough and therefore was unable to resolve fragments close in size. This leads to a lack of separation of fragments which were close in size. If all of the digests produce fragments that add up one may infer the position of the REN (restriction endonuclease) sites by placing them in spots on the original DNA fragment that would satisfy the fragment sizes produced by all three digests | 1 | Applied and Interdisciplinary Chemistry |
It has also been used as an adjunct infusion during general anesthesia. In this application, it has been shown to decrease post-operative delirium, pain, nausea and opioid use. | 0 | Theoretical and Fundamental Chemistry |
The amount of carbon dioxide varies naturally in a dynamic equilibrium with photosynthesis of land plants. The natural carbon sinks are:
*Soil is a carbon store and active carbon sink.
* Photosynthesis by terrestrial plants with grass and trees allows them to serve as carbon sinks during growing seasons.
* Absorption of carbon dioxide by the oceans via solubility and biological pumps.
Artificial carbon sinks are those that store carbon in building materials or deep underground (geologic carbon sequestration). No major artificial systems remove carbon from the atmosphere on a large scale yet.
Public awareness of the significance of sinks has grown since passage of the 1997 Kyoto Protocol, which promotes their use as a form of carbon offset. | 0 | Theoretical and Fundamental Chemistry |
Magnetic nanochains are a new class of magnetoresponsive and superparamagnetic nanostructures with highly anisotropic shapes which can be manipulated using magnetic field and magnetic field gradient. Such nanochains consist of self-assembled nanoparticle clusters which are magnetically assembled and fixated into a chain. Among the various linking methods used are silica coating, polyacrylic acid (PAA) coating, tetraethoxysilane condensation, biotinylation or glucose decomposition. Typically, the primary building blocks of these nanostructures are individual superparamagnetic iron oxide nanoparticles (SPIONs). Nanoparticle clusters which are composed of a number of individual magnetic nanoparticles (ca. 100 SPIONs) are known as magnetic nanobeads with a diameter of 50–200 nanometers.
The force exerted on a particle depends on the strength, direction, and dynamics of the applied magnetic field as well as the position and orientation of local magnetic dipoles. Dynamic magnetic fields allow for the greatest range of control over chain shape. Of principal interest is the force exerted on the ends of the chain as a result of a dynamic field. The effect of Larmor precession with a row of magnetic colloids results in dynamic interactions dependent on the field precession angle. In fact, sweeping through the magic angle flips sign of the dipole-dipole interaction. In a field precessing quickly around the z-axis, the force exerted on the end of the chain is given by
where is the dipole moment, is the bead diameter, is the angular frequency of the field precession, is the rate of change of the filament path, is the viscous drag coefficient and is the unit vector of the plane perpendicular to the tangent of the filament curve. This produces a periodic magnetic force. However, under fast precession, the second term remains non-zero and scales with . At low , the magnetic torque dominates and the chain winds around itself. With a high , the bending modulus dominates the energetic landscape and filaments form branched gels with a field-dependent bulk modulus.
The applied load on a filament is generally limited by the polymer linking method. The elastic strain regime for a simple covalently linked filament is short and are taken as inextensible under most conditions. If tensile forces become too large, plastic deformation can occur usually resulting in bond breaking and polymer disentanglement. These irreversible changes can result in the permanent change in the bending modulus which ultimately effects the filament performance. | 0 | Theoretical and Fundamental Chemistry |
*nEXO experiment:
**As EXO-200's successor, nEXO is planned to be a ton-scale experiment and part of the next generation of 0νββ experiments. The detector material is planned to weigh about 5 t, serving a 1% energy resolution at the -value. The experiment is planned to deliver a lifetime sensitivity of about years after 10 years of data-taking.
*LEGEND (experiment)
* SuperNEMO | 0 | Theoretical and Fundamental Chemistry |
In the early 1990s, the market was becoming more familiar with the potential of laser peening to increase fatigue life. In 1991, the U.S. Air Force introduced Battelle and Wagner engineers to GE Aviation to discuss the potential application of laser peening to address a foreign object damage (FOD) problem with fan blades in the General Electric F101 engine powering the Rockwell B-1B Lancer Bomber. The resulting tests showed that laser peened fan blades severely notched after laser peening had the same fatigue life as a new blade. After further development, GE Aviation licensed the laser shock peening technology from Battelle, and in 1995, GE Aviation and the U.S. Air Force made the decision to move forward with production development of the technology. GE Aviation began production laser peening of the F101 fan blades in 1998.
The demand for industrial laser systems required for GE Aviation to go into production attracted several of the laser shock peening team at Battelle to start LSP Technologies, Inc. in 1995 as the first commercial supplier of laser peening equipment. Led by founder Jeff Dulaney, LSP Technologies designed and built the laser systems for GE Aviation to perform production laser peening of the F101 fan blades. Through the late 1990s and early 2000s, the U.S. Air Force continued to work with LSP Technologies to mature the laser shock peening production capabilities and implement production manufacturing cells.
In the mid 1990s, independent of the laser peening developments ongoing in the United States and France, Yuji Sano of the Toshiba Corporation in Japan initiated the development of a laser peening system capable of laser peening welds in nuclear plant pressure vessels to mitigate stress corrosion cracking in these areas. The system used a low-energy pulsed laser operating at a higher pulse frequency than the higher powered lasers. The laser beam was introduced into the pressure vessels through articulated tubes. Because the pressure vessels were filled with water, the process did not require a water overlay over the irradiated surface. However, the beam had to travel some distance through the water, necessitating using a shorter wavelength beam, 532 nm, to minimize dielectric breakdown of the beam in the water, instead of the 1054 nm beam used in the United States and France. Also, it was impractical to consider using an opaque overlay. This process is now known as Laser Peening without Coating (LPwC). It began to be applied to Japanese boiling water and pressurized water reactors in 1999.
Also in the 1990s a significant laser peening research group was formed at the Madrid Polytechnic University by José Ocaña. Their work includes both experimental and theoretical studies using low-energy pulsed lasers both without and with an opaque overlay. | 1 | Applied and Interdisciplinary Chemistry |
Chelating resins are a class of ion-exchange resins. They are almost always used to bind cations, and utilize chelating agents covalently attached to a polymer matrix. Chelating resins have the same bead form and polymer matrix as usual ion exchangers. Their main use is for pre-concentration of metal ions in a dilute solution. Chelating ion-exchange resins are used for brine decalcification in the chlor-alkali industry, the removal of boron from potable water, and the recovery of precious metals in solutions. | 0 | Theoretical and Fundamental Chemistry |
MAPs bind to the tubulin subunits that make up microtubules to regulate their stability. A large variety of MAPs have been identified in many different cell types, and they have been found to carry out a wide range of functions. These include both stabilizing and destabilizing microtubules, guiding microtubules towards specific cellular locations, cross-linking microtubules and mediating the interactions of microtubules with other proteins in the cell.
Within the cell, MAPs bind directly to the tubulin dimers of microtubules. This binding can occur with either polymerized or depolymerized tubulin, and in most cases leads to the stabilization of microtubule structure, further encouraging polymerization. Usually, it is the C-terminal domain of the MAP that interacts with tubulin, while the N-terminal domain can bind with cellular vesicles, intermediate filaments or other microtubules. MAP-microtubule binding is regulated through MAP phosphorylation. This is accomplished through the function of the microtubule-affinity-regulating-kinase (MARK) protein. Phosphorylation of the MAP by the MARK causes the MAP to detach from any bound microtubules. This detachment is usually associated with a destabilization of the microtubule causing it to fall apart. In this way the stabilization of microtubules by MAPs is regulated within the cell through phosphorylation. | 1 | Applied and Interdisciplinary Chemistry |
Although cells undergo multiple steps in order to ensure there are no mutations in the genetic sequence, sometimes specific deletions and other genetic changes during Okazaki fragment maturation go unnoticed. Because Okazaki fragments are the set of nucleotides for the lagging strand, any alteration including deletions, insertions, or duplications from the original strand can cause a mutation if it is not detected and fixed. Other causes of mutations include problems with the proteins that aid in DNA replication. For example, a mutation related to primase affects RNA primer removal and can make the DNA strand more fragile and susceptible to breaks. Another mutation concerns polymerase α, which impairs the editing of the Okazaki fragment sequence and incorporation of the protein into the genetic material. Both alterations can lead to chromosomal aberrations, unintentional genetic rearrangement, and a variety of cancers later in life.
In order to test the effects of the protein mutations on living organisms, researchers genetically altered lab mice to be homozygous for another mutation in protein related to DNA replication, flap endonuclease 1, or FEN1. The results varied based on the specific gene alterations. The homozygous knockout mutant mice experienced a "failure of cell proliferation" and "early embryonic lethality" (27). The mice with the mutation F343A and F344A (also known as FFAA) died directly after birth due to complications in birth including pancytopenia and pulmonary hypoplasia. This is because the FFAA mutation prevents the FEN1 from interacting with PCNA (proliferating cell nuclear antigen), consequently not allowing it to complete its purpose during Okazaki fragment maturation. The interaction with this protein is considered to be the key molecular function in the FEN1's biological function. The FFAA mutation causes defects in RNA primer removal and long-base pair repair, of which cause many breaks in the DNA. Under careful observation, cells homozygous for FFAA FEN1 mutations seem to display only partial defects in maturation, meaning mice heterozygous for the mutation would be able to survive into adulthood, despite sustaining multiple small nicks in their genomes. Inevitably however, these nicks prevent future DNA replication because the break causes the replication fork to collapse and causes double strand breaks in the actual DNA sequence. In time, these nicks also cause full chromosome breaks, which could lead to severe mutations and cancers. Other mutations have been implemented with altered versions of Polymerase α, leading to similar results. | 1 | Applied and Interdisciplinary Chemistry |
NRTL binary interaction parameters have been published in the Dechema data series and are provided by NIST and DDBST. In 2023 the DDBST database of VLE-data in combination with the smiles notation for molecules has been used as input to generate via a machine learning algorithm a giant database of 100 million NRTL binary interaction parameter sets. It covers a list of 10 thousand compounds. | 0 | Theoretical and Fundamental Chemistry |
Nitrification is the biological conversion of organic and inorganic nitrogenous compounds from a reduced state to a more oxidized state, based on the action of two different bacteria types. Nitrification is strictly an aerobic process in which the end product is nitrate (). The process of nitrification oxidizes ammonium (from the wastewater) to nitrite (), and then nitrite is oxidized to nitrate (). | 1 | Applied and Interdisciplinary Chemistry |
*A commercial source for the cyanide group is diethylaluminum cyanide which can be prepared from triethylaluminium and HCN. It has been used in nucleophilic addition to ketones. For an example of its use see: Kuwajima Taxol total synthesis
* Cyanide ions facilitate the coupling of dibromides. Reaction of α,α′-dibromoadipic acid with sodium cyanide in ethanol yields the cyano cyclobutane:
* Aromatic nitriles can be prepared from base hydrolysis of trichloromethyl aryl ketimines () in the Houben-Fischer synthesis
* Nitriles can be obtained from primary amines via oxidation. Common methods include the use of potassium persulfate, Trichloroisocyanuric acid, or anodic electrosynthesis.
* α-Amino acids form nitriles and carbon dioxide via various means of oxidative decarboxylation. Henry Drysdale Dakin discovered this oxidation in 1916.
* From aryl carboxylic acids (Letts nitrile synthesis) | 0 | Theoretical and Fundamental Chemistry |
* Flavor: the artificial sweetener aspartame has two enantiomers. -aspartame tastes sweet whereas -aspartame is tasteless.
* Odor: R-(–)-carvone smells like spearmint whereas S-(+)-carvone smells like caraway.
* Drug effectiveness: the antidepressant drug citalopram is sold as a racemic mixture. However, studies have shown that only the (S)-(+) enantiomer (escitalopram) is responsible for the drug's beneficial effects.
* Drug safety: ‑penicillamine is used in chelation therapy and for the treatment of rheumatoid arthritis whereas ‑penicillamine is toxic as it inhibits the action of pyridoxine, an essential B vitamin. | 0 | Theoretical and Fundamental Chemistry |
The Swedish ethyl acetate method (SweEt) is a method for chemical analysis of pesticide residues in food using ethyl acetate as an extraction medium followed by analysis with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). It was developed by the Swedish National Food Agency (National Reference Laboratory for pesticide analysis) for quantitative analysis of over 500 pesticides in fruits, vegetables, cereals and products of animal origin. | 0 | Theoretical and Fundamental Chemistry |
In the body, stores of fat are referred to as adipose tissue. In these areas, intracellular triglycerides are stored in cytoplasmic lipid droplets. When lipase enzymes are phosphorylated, they can access lipid droplets and through multiple steps of hydrolysis, breakdown triglycerides into fatty acids and glycerol. Each step of hydrolysis leads to the removal of one fatty acid. The first step and the rate-limiting step of lipolysis is carried out by adipose triglyceride lipase (ATGL). This enzyme catalyzes the hydrolysis of triacylglycerol to diacylglycerol. Subsequently, hormone-sensitive lipase (HSL) catalyzes the hydrolysis of diacylglycerol to monoacylglycerol and monoacylglycerol lipase (MGL) catalyzes the hydrolysis of monoacylglycerol to glycerol.
Perilipin 1A is a key protein regulator of lipolysis in adipose tissue. This lipid droplet-associated protein, when deactivated, will prevent the interaction of lipases with triglycerides in the lipid droplet and grasp the ATGL co-activator, comparative gene identification 58 (CGI-58) (a.k.a. ABHD5). When perilipin 1A is phosphorylated by PKA, it releases CGI-58 and it expedites the docking of phosphorylated lipases to the lipid droplet. CGI-58 can be further phosphorylated by PKA to assist in its dispersal to the cytoplasm. In the cytoplasm, CGI-58 can co-activate ATGL. ATGL activity is also impacted by the negative regulator of lipolysis, G0/G1 switch gene 2 (G0S2). When expressed, G0S2 acts as a competitive inhibitor in the binding of CGI-58. Fat-specific protein 27 (FSP-27) (a.k.a. CIDEC) is also a negative regulator of lipolysis. FSP-27 expression is negatively correlated with ATGL mRNA levels. | 1 | Applied and Interdisciplinary Chemistry |
Precipitation and surface water leaches dissolved organic carbon (DOC) from vegetation and plant litter and percolates through the soil column to the saturated zone. The concentration, composition, and bioavailability of DOC are altered during transport through the soil column by various physicochemical and biological processes, including sorption, desorption, biodegradation and biosynthesis. Hydrophobic molecules are preferentially partitioned onto soil minerals and have a longer retention time in soils than hydrophilic molecules. The hydrophobicity and retention time of colloids and dissolved molecules in soils are controlled by their size, polarity, charge, and bioavailability. Bioavailable DOM is subjected to microbial decomposition, resulting in a reduction in size and molecular weight. Novel molecules are synthesized by soil microbes, and some of these metabolites enter the DOC reservoir in groundwater. | 1 | Applied and Interdisciplinary Chemistry |
Di-tert-butyl dicarbonate is a reagent widely used in organic synthesis. Since this compound can be regarded formally as the acid anhydride derived from a tert-butoxycarbonyl (Boc) group, it is commonly referred to as Boc anhydride. This pyrocarbonate reacts with amines to give N-tert-butoxycarbonyl or so-called Boc derivatives. These carbamate derivatives do not behave as amines, which allows certain subsequent transformations to occur that would be incompatible with the amine functional group. The Boc group can later be removed from the amine using moderately strong acids (e.g., trifluoroacetic acid). Thus, Boc serves as a protective group, for instance in solid phase peptide synthesis. Boc-protected amines are unreactive to most bases and nucleophiles, allowing for the use of the fluorenylmethyloxycarbonyl group (Fmoc) as an orthogonal protecting group. | 0 | Theoretical and Fundamental Chemistry |
Amongst incidental scenarios, natural gas releases have become particularly relevant within the process industry environment. With an overall composition of 94.7% of methane, it is important to consider how this gas can cause incremental damage when it is released. Methane gas is a non-toxic, flammable gas, that, at higher concentrations, can behave as an asphyxiant due to oxygen displacement from the lungs. The main concern with methane is related to its flammability and the potential damage that could be dealt to its surroundings if the high pressure jet were to ignite into a jet fire.
Three parameters that must be considered when dealing with flammable gasses are their flash point (FP), upper flammability limit (UFL) and lower flammability limit (LFL), as they are set values for any compound at a specific pressure and temperature. If we consider the fire triangle model, to induce a combustion reaction three components are needed: a fuel, an oxidizing agent and heat.
When release happens in an ambient filled with air, the oxidizing agent will be oxygen (air has a constant concentration of 21% in standard conditions). At an almost pure concentration, a few centimeters from the exit plane, the concentration of natural gas is too high and oxygen too low to generate any kind of combustion reaction, but as the high pressure jet develops, the concentration of its components will dilute as air entrainment increases, allowing an enrichment of oxygen within the jet. Assuming a constant concentration for oxygen, the jet must dilute enough to enter within its flammability range; below its UFL. Within this range, a flammable mixture can be made and any source of heat can jump-start the reaction.
To properly judge the damage and potential risk that the jet fire can generate, several studies regarding the maximum distance that the cloud generated by the jet can reach have been made. As dilution of the jet continues due to air entrainment in the farfield, going below its UFL, the maximum distance that the flammable mixture can reach is at the point in which the concentration of the cloud is equals to the LFL of the gas, as it is the lowest concentration allowable that permits the formation of a flammable mixture between air and natural gas at standard conditions (the LFL for natural gas is 4% ).
Considering a free jet at sub-critical pressure (beyond the nearfield zone), its mean volume fraction axial concentration decay of any gas released in air can be defined as follows: | 1 | Applied and Interdisciplinary Chemistry |
Le Bail analysis fits parameters using a steepest descent minimization process. Specifically, the method is least squares analysis, which is an iterative process that is discussed later in this article. The parameters being fitted include the unit-cell parameters, the instrumental zero error, peak width parameters, and peak shape parameters. First, the Le Bail method defines an arbitrary starting value for the intensities (I). This value is ordinarily set to one, but other values may be used. While peak positions are constrained by the unit cell parameters, intensities are unconstrained. The equation to calculate intensities is:
In the equation, I is the intensity observed at a particular step and y(obs) is the observed profile point. y(calc) is the A single intensity value may contain more than one peak. Other peaks may be calculated similarly. The final intensity for a peak is calculated as y(calc) = y(1) + y(2). The summation is carried out over all contributing profile points for a particular 2-theta bin. The summation process is known as profile intensity partitioning, and it works over any number of peaks. Le Bail technique works especially well with overlapping intensities since in this method the intensity is allotted based on the multiplicity of the intensities that contribute to a particular peak.
The somewhat arbitrary choice of starting values produces a bias in the calculated values. The refinement process continues by setting the new calculated structure factor to the observed structure factor value. The process is then repeated with the new structure factor estimate. At this point, the unit cell, background, peak widths, peak shape, and resolution function are refined, and the parameters are improved. The structure factor is then reset to the new structure factor value, and the process begins again. Structural refinement can continue with whole profile fitting techniques or further treatment of peak overlap. Probabilistic approaches may also be used to treat peak overlap. | 0 | Theoretical and Fundamental Chemistry |
This compound is used for bioconjugation. The target, which contains a terminal alkyne functional group, is treated with the organic azide in the presence of a Cu(I) catalyst. The resulting 1,2,3-triazole is fluorescent. The coumarin backbone is chosen to be used as the profluorophore due to its small size, biocompatibility, and its ability to be easily manipulated synthetically. Illustrative of this is the labeling of biological compounds such as the protein calmodulin. Neither the azidocoumarin nor the alkyne substrate fluoresce. Azidocoumarin is also inert in biological systems and insensitive to pH and solvent. A variety of azidocoumarin compounds have been evaluated. | 1 | Applied and Interdisciplinary Chemistry |
In the process of photosynthesis, green plants use the energy of sunlight to split water into free oxygen (which is released) and free hydrogen. Rather than attempt to store the hydrogen, plants immediately capture carbon dioxide from the air to allow the hydrogen to reduce it to storable fuels such as hydrocarbons (plant oils and terpenes) and polyalcohols (glycerol, sugars and starches). In the methanol economy, any process which similarly produces free hydrogen, proposes to immediately use it "captively" to reduce carbon dioxide into methanol, which, like plant products from photosynthesis, has great advantages in storage and transport over free hydrogen itself.
Methanol is a liquid under normal conditions, allowing it to be stored, transported and dispensed easily, much like gasoline and diesel fuel. It can also be readily transformed by dehydration into dimethyl ether, a diesel fuel substitute with a cetane number of 55.
Methanol is water-soluble: An accidental release of methanol in the environment would cause much less damage than a comparable gasoline or crude oil spill. Unlike these fuels, methanol is biodegradable and totally soluble in water, and would be rapidly diluted to a concentration low enough for microorganism to start biodegradation. This effect is already exploited in water treatment plants, where methanol is already used for denitrification and as a nutrient for bacteria. Accidental release causing groundwater pollution has not been thoroughly studied yet, though it is believed that it might undergo relatively rapid. | 1 | Applied and Interdisciplinary Chemistry |
Minima naturalia ("natural minima") were theorized by Aristotle as the smallest parts into which a homogeneous natural substance (e.g., flesh, bone, or wood) could be divided and still retain its essential character. In this context, "nature" means formal nature. Thus, "natural minimum" may be taken to mean "formal minimum": the minimum amount of matter necessary to instantiate a certain form.
Speculation on minima naturalia in late Antiquity, in the Islamic world, and by Scholastic and Renaissance thinkers in Europe provided a conceptual bridge between the atomism of ancient Greece and the mechanistic philosophy of early modern thinkers like Descartes, which in turn provided a background for the rigorously mathematical and experimental atomic theory of modern science. | 1 | Applied and Interdisciplinary Chemistry |
Within the citric acid cycle in humans, propionyl-CoA, which interacts with oxaloacetate to form methylcitrate, can also catalyzed into methylmalonyl-CoA through carboxylation by propionyl-CoA carboxylase (PCC). Methylmalonyl-CoA is later transformed to succinyl-CoA to be further used in the tricarboxylic acid cycle. PCC not only catalyzes the carboxylation of propionyl-CoA to methylmalonyl-CoA, but also acts on several different acyl-CoAs. Nevertheless, its highest binding affinity is to propionyl-CoA. It was further shown that propionyl-CoA transformation is inhibited by the absence of several TCA markers, such as glutamate. The mechanism is shown by the figure to the left. | 1 | Applied and Interdisciplinary Chemistry |
The Geochemical Journal is a peer-reviewed open-access scientific journal covering all aspects of geochemistry and cosmochemistry. It is published by the Geochemical Society of Japan and the editor-in-chief is Katsuhiko Suzuki. | 0 | Theoretical and Fundamental Chemistry |
Perilipin, also known as lipid droplet-associated protein, perilipin 1, or PLIN, is a protein that, in humans, is encoded by the PLIN gene. The perilipins are a family of proteins that associate with the surface of lipid droplets. Phosphorylation of perilipin is essential for the mobilization of fats in adipose tissue. | 1 | Applied and Interdisciplinary Chemistry |
Sludge is a semi-solid slurry that can be produced from a range of industrial processes, from water treatment, wastewater treatment or on-site sanitation systems. It can be produced as a settled suspension obtained from conventional drinking water treatment, as sewage sludge from wastewater treatment processes or as fecal sludge from pit latrines and septic tanks. The term is also sometimes used as a generic term for solids separated from suspension in a liquid; this soupy material usually contains significant quantities of interstitial water (between the solid particles). Sludge can consist of a variety of particles, such as animal manure.
Industrial wastewater treatment plants produce solids that are also referred to as sludge. This can be generated from biological or physical-chemical processes.
In the activated sludge process for wastewater treatment, the terms "waste activated sludge" and "return activated sludge" are used.
In food processing and beverage-making industries, sludge can have a high protein content and can contain other nutrients that can be used for beneficial purposes such as processing for animal feed; this avoids having to dispose of the sludge at a landfill. | 1 | Applied and Interdisciplinary Chemistry |
ATP is involved in signal transduction by serving as substrate for kinases, enzymes that transfer phosphate groups. Kinases are the most common ATP-binding proteins. They share a small number of common folds. Phosphorylation of a protein by a kinase can activate a cascade such as the mitogen-activated protein kinase cascade.
ATP is also a substrate of adenylate cyclase, most commonly in G protein-coupled receptor signal transduction pathways and is transformed to second messenger, cyclic AMP, which is involved in triggering calcium signals by the release of calcium from intracellular stores. This form of signal transduction is particularly important in brain function, although it is involved in the regulation of a multitude of other cellular processes. | 1 | Applied and Interdisciplinary Chemistry |
Dynamic covalent chemistry has allowed access to a wide variety of supramolecular structures. Using the above reactions to link molecular fragments, higher order materials have been made. These materials include macrocycles, COFs, and molecular knots. The applications of these products have been used in gas storage, catalysis, and biomedical sensing, among others. | 0 | Theoretical and Fundamental Chemistry |
*[https://global.oup.com/academic/product/african-american-women-chemists-in-the-modern-era-9780190615178?facet_narrowbytype_facet=General%20Interest&type=listing&lang=en&cc=us# African American Women Chemists in the Modern Era] (2018)
*[https://global.oup.com/academic/product/african-american-women-chemists-9780199742882?cc=us&lang=en& African-American Women Chemists] (2011) | 1 | Applied and Interdisciplinary Chemistry |
Approaches for delivering unaltered natural products using polymeric carriers is of widespread interest. Dendrimers have been explored for the encapsulation of hydrophobic compounds and for the delivery of anticancer drugs. The physical characteristics of dendrimers, including their monodispersity, water solubility, encapsulation ability, and large number of functionalizable peripheral groups make these macromolecules appropriate candidates for drug delivery vehicles. | 0 | Theoretical and Fundamental Chemistry |
To produce concrete, fresh plant material is extracted with nonpolar solvents. On evaporation of the solvent, a semi-solid residue of essential oils, waxes, resins and other oil-soluble plant chemicals remains.
The solvent used for extraction must be chosen carefully regarding its polarity and boiling point. If the boiling point is too high, compounds that are readily deactivated by heat might be destroyed, leading to a loss of certain fragrance ingredients during evaporation.
The resulting residue after evaporation consists mostly of heavier nonvolatile substances, which give concrete its "waxy" properties.
Putting the plant materials under high pressure before treating it with solvents has been found to greatly increase the yield of the concrete. This is because high pressure causes the cells to burst, which allows the glucoside and diastase in the plants to react more freely. | 0 | Theoretical and Fundamental Chemistry |
Bacteria and archaea reproduce through asexual reproduction, usually by binary fission. Genetic exchange and recombination still occur, but this is a form of horizontal gene transfer and is not a replicative process, simply involving the transference of DNA between two cells, as in bacterial conjugation. | 1 | Applied and Interdisciplinary Chemistry |
In some cases, simply changing the way the material is processed can influence the microstructure. An example is the titanium alloy TiAl6V4. Its microstructure and mechanical properties are enhanced using SLM (selective laser melting) which is a 3D printing technique using powder and melting the particles together using high powered laser. Other conventional techniques for improving the microstructure are thermal processes. Those processes rely in the principle that an increase in temperature will induce the reduction or annihilation of pores. Hot isostatic pressing (HIP) is a manufacturing process, used to reduce the porosity of metals and increase the density of many ceramic materials. This improves the material's mechanical properties and workability.
The HIP process exposes the desired material to an isostatic gas pressure as well as high temperature in a sealed vessel (high pressure). The gas used during this process is mostly Argon. The gas needs to be chemically inert so that no reaction occurs between it and the sample. The pressure is achieved by simply applying heat to the hermetically sealed vessel. However, some systems also associate gas pumping to the process to achieve the required pressure level. The pressure applied on the materials is equal and comes from all directions (hence the term “isostatic”). When castings are treated with HIP, the simultaneous application of heat and pressure eliminates internal voids and microporosity through a combination of plastic deformation, creep, and diffusion bonding; this process improves fatigue resistance of the component. | 1 | Applied and Interdisciplinary Chemistry |
In the United States, an ADS system (BDS) was developed for the U.S. Postal Service following the 2001 anthrax attacks. The first detection systems in U.S. postal services were installed in 2006. To counter such problems in the future, the United States federal government set up a program called BioWatch, which operates in more than 21 cities in the US.
In Canada, an autonomous pathogen detection system was developed by a biotechnology company called Kraken Sense for the Greater Toronto Airports Authority (GTAA) during the COVID-19 pandemic. | 0 | Theoretical and Fundamental Chemistry |
Taking a look at the thermodynamics at the surface of the film, it is seen that bonds are broken, releasing energy, and bonds are formed, confining energy. The thermodynamics involved were modeled by the two Germans W.Kossel and N.Stranski in 1920. This model is called Terrace ledge kink model (TLK).
The adatom can create more than one bond with the crystal, depending on the structure of the crystal. If it is a simple cubic lattice, the adatom can have up to 6 bonds, whereas in a face-centered cubic lattice, it can have up to 12 nearest neighbors. The more bonds created, the more energy is confined, making it harder to desorb the adatom.
A special site for an adatom is a kink, where exactly half of the bonds with the surface can be created, also called the "half-crystal position". | 0 | Theoretical and Fundamental Chemistry |
Solid-phase microextraction (SPME), is a solid phase extraction technique that involves the use of a fiber coated with an extracting phase, that can be a liquid (polymer) or a solid (sorbent), which extracts different kinds of analytes (including both volatile and non-volatile) from different kinds of media, that can be in liquid or gas phase. The quantity of analyte extracted by the fibre is proportional to its concentration in the sample as long as equilibrium is reached or, in case of short time pre-equilibrium, with help of convection or agitation. | 0 | Theoretical and Fundamental Chemistry |
With the recent elucidation of the structures of the catalytic portion of human HMGR enzyme complexed with six different statins by a series of crystallography studies, new possibilities have opened up for the rational design and optimization of even better HGMR inhibitors.
A new study using comparative molecular field analysis (CoMFA) to establish three-dimensional quantitative structure-activity relationship (3D QSAR), while searching for novel active pharmacophores as potentially potent HGMR inhibitors, was recently published. Using this novel technique researchers were able to screen for compounds with high screening scores. In addition to the conventional statin-like compounds with HMG-like moiety, eight additional compounds with completely different pharmacophore structure were found. This structure-based virtual screening procedure is considered promising for rational quest and optimization of potential novel HGMR inhibitors. | 1 | Applied and Interdisciplinary Chemistry |
Centered on localized gene delivery, Mao's research proposed biodegradable polymer coatings for sequential DNA release from implantable devices. This was built on her PhD research on the multilayer films. In 2016, she and her team pioneered the idea of using retrograde transport proteins to specifically deliver drugs for treating respiratory issues linked to spinal cord injury. In related research, she collaborated with Harry Goshgarian and Abdulghani Sankari to advance nanotherapeutics by integrating retrograde transport proteins, adenosine receptor antagonists, and nanoparticle carriers. Furthermore, she proposed a new technique for delivering drugs specifically to the central nervous system (CNS) using nanoparticles that are chemically attached to neural tract tracer proteins and can be transported along specific neural pathways, allowing them to bypass the blood–brain barrier and target the CNS directly. Mao used human embryonic stem cells (hESCs) for assessing nanotoxicology, specifically, the effect of nanoparticle size on the viability, pluripotency, neuronal differentiation, and DNA methylation of hESCs. Her work revealed a type of gold nanoparticles to be highly toxic and demonstrated the potential of hESCs in predicting nanotoxicity. | 1 | Applied and Interdisciplinary Chemistry |
RIN for a sample is computed using several characteristics of an RNA electropherogram trace, with the first two listed below being most significant. RIN assigns an electropherogram a value of 1 to 10, with 10 being the least degraded. All the following descriptions apply to mammalian RNA because RNAs in other species have different rRNA sizes:
The total RNA ratio is calculated by taking the ratio of the area under the 18S and 28S rRNA peaks to the total area under the graph, a large number here is desired, indicating much of the rRNA is still at these sizes and thus little to no degradation has occurred. An ideal ratio can be seen in figure 1, where almost all of the RNA is in the 18S and 28S RNA peaks.
For the height of 28S peak, a large value is desired. 28S, the most prominent rRNA species, is used in RIN calculation as it is typically degraded more quickly than 18S rRNA, and so measuring its peak height allows for detection of the early stages of degradation. Again, this is seen in figure 1, where the 28S peak is the largest, and so this is good.
The fast region is the area between the 18S and 5S rRNA peaks on an electropherogram. Initially, as the fast area ratio value increases, it indicates degradation of the 18S and 28S rRNA to an intermediate size, though the ratio subsequently decreases as RNA degrades further, to even smaller sizes. Thus, a low value doesn't necessarily indicate either good or bad RNA integrity.
A small marker height is desired, indicating only small amounts of RNA have been degraded and proceeded to the smallest lengths, indicated by the short marker. If a large number is found here, that indicates that large amounts of the rRNAs have been degraded to small pieces that would be found closer to this marker. This situation can be seen in the poor quality RNA electropherogram found in figure 2, where the height of the peak over the marker (far left) is very large, so the RNA has been greatly degraded.
In prokaryotic samples, the algorithm is somewhat different, but the Agilent 2100 Bioanalyzer Expert software is able to calculate RIN for prokaryotic samples now as well. The difference likely arises from the fact that, while mammalian samples have 28S and 18S ribosomal RNAs as their predominant species, prokaryotic RNAs have the sizes shifted slightly smaller, to 23S and 16S, so the algorithm must be shifted to accommodate that. Another crucial fact about calculating prokaryotic RNA integrity numbers is that RIN has not been validated to the extent that it has for eukaryotic RNA. It has been shown that higher RIN values correlate with better downstream results in eukaryotes, but this hasn't been done as extensively for prokaryotes, so it may mean less in prokaryotes.
These electropherograms for calculating RIN are done using the Agilent Bioanalyzer machine, which is capable of performing electrophoresis and generating the electropherograms. The Agilent 2100 software is uniquely able to perform the RIN software, as the exact algorithm is proprietary, so there are additional important RNA electropherogram features that are used in its calculation that are not publicly available. | 1 | Applied and Interdisciplinary Chemistry |
Thionyl chloride is a component of lithium–thionyl chloride batteries, where it acts as the positive electrode (in batteries: cathode) with lithium forming the negative electrode (anode); the electrolyte is typically lithium tetrachloroaluminate. The overall discharge reaction is as follows:
These non-rechargeable batteries had many advantages over other forms of lithium batteries such as a high energy density, a wide operational temperature range, and long storage and operational lifespans. However, their high cost, non-rechargeability, and safety concerns have limited their use. The contents of the batteries are highly toxic and require special disposal procedures; additionally, they may explode if shorted. The technology was used on the Sojourner Mars rover. | 0 | Theoretical and Fundamental Chemistry |
The number of RNAPs in bacterial cells (e.g., E. coli) have been shown to be smaller than the number of sigma factors. Consequently, if a certain sigma factor is overexpressed, not only will increase the expression levels of genes whose promoters have preference for that sigma factor, but it will also reduce the probability that genes with promoters with preference for other sigma factors.
Meanwhile, transcription initiation has two major rate limiting steps: the closed and the open complex formation. However, only the dynamics of the first step depends on the concentration of sigma factors. Interestingly, the fastest is the closed complex formation relative to the open complex formation, the less responsive is a promoter to changes in sigma factors’ concentration (see for a model and empirical data of this phenomenon). | 1 | Applied and Interdisciplinary Chemistry |
Reis is a researcher who has been involved in the field of biomaterials since 1990. He has worked with several universities and companies abroad.
Some of Reis' research has been on liver and neurological tissues regeneration, new strategies for antimicrobial materials, innovative high-throughput approaches for studying cell/materials interactions, as well as on TE approaches for developing different 3D disease models, including different cancer models, and therapies for treatment of diabetes and Alzheimers.
Reis has also been responsible for several cooperation programs with universities and companies worldwide. He has coordinated four major EU research projects, including the STREP "HIPPOCRATES".
Under HORIZON 2020, Reis was the coordinator of the ERA Chairs FoReCast grant for 3B's-UMinho. He has coordinated two TWINNING projects Gene2Skin and Chem2Nature, and is currently coordinating another TWINNING project. Until 2021, he was the coordinator of the 15 MEuros EC funded TEAMING proposal, "The Discoveries Centre for Regenerative and Precision Medicine" with UCL - University College London, UPorto, UAveiro, ULisboa, and UNova Lisboa. He is also the PI of a major project of the Portuguese roadmap for strategic infrastructures, TERM Research Hub. | 1 | Applied and Interdisciplinary Chemistry |
Calixarenes and related formaldehyde-arene condensates are one class of hosts that form inclusion compounds. One famous illustration is the adduct with cyclobutadiene, which otherwise is unstable. | 0 | Theoretical and Fundamental Chemistry |
also considered the symmetrized function:
which they referred to as the "divergence", though today the "KL divergence" refers to the asymmetric function (see for the evolution of the term). This function is symmetric and nonnegative, and had already been defined and used by Harold Jeffreys in 1948; it is accordingly called the Jeffreys divergence.
This quantity has sometimes been used for feature selection in classification problems, where and are the conditional pdfs of a feature under two different classes. In the Banking and Finance industries, this quantity is referred to as Population Stability Index (PSI), and is used to assess distributional shifts in model features through time.
An alternative is given via the -divergence,
which can be interpreted as the expected information gain about from discovering which probability distribution is drawn from, or , if they currently have probabilities and respectively.
The value gives the Jensen–Shannon divergence, defined by
where is the average of the two distributions,
We can also interpret as the capacity of a noisy information channel with two inputs giving the output distributions and . The Jensen–Shannon divergence, like all -divergences, is locally proportional to the Fisher information metric. It is similar to the Hellinger metric (in the sense that it induces the same affine connection on a statistical manifold).
Furthermore, the Jensen–Shannon divergence can be generalized using abstract statistical M-mixtures relying on an abstract mean M. | 0 | Theoretical and Fundamental Chemistry |
Interferometric microscopy or imaging interferometric microscopy is the concept of microscopy which
is related to holography, synthetic-aperture imaging, and off-axis-dark-field illumination techniques.
Interferometric microscopy allows enhancement of resolution of optical microscopy due to interferometric (holographic)
registration of several partial images (amplitude and phase) and the numerical combining. | 0 | Theoretical and Fundamental Chemistry |
* "Stirred pots and empty tubes" (with A. Varma). In (N.R. Amundson and L. Lapidus, eds.). Chemical Reactor Theory. Englewood Cliffs, NJ: Prentice-Hall, 1977 (pp. 79–155).
* "Reactor Steady-State Multiplicity and Stability" (with A. Varma and M. Morbidelli). In (J.J. Carberry and A. Varma, eds.). Chemical Reactor and Reaction Engineering. New York: Marcel Dekker, 1987 (Ch. 15). | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a mixture is a material made up of two or more different chemical substances which are physically bonded. A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the form of solutions, suspensions and colloids.
Mixtures are one product of mechanically blending or mixing chemical substances such as elements and compounds, without chemical bonding or other chemical change, so that each ingredient substance retains its own chemical properties and makeup. Despite the fact that there are no chemical changes to its constituents, the physical properties of a mixture, such as its melting point, may differ from those of the components. Some mixtures can be separated into their components by using physical (mechanical or thermal) means. Azeotropes are one kind of mixture that usually poses considerable difficulties regarding the separation processes required to obtain their constituents (physical or chemical processes or, even a blend of them). | 0 | Theoretical and Fundamental Chemistry |
N-Oxoammonium salts are a class of organic compounds with the formula [RR=O]X. The cation [RR=O] is of interest for the dehydrogenation of alcohols. Oxoammonium salts are diamagnetic, whereas the nitroxide has a doublet ground state. A prominent N-oxoammonium salt is prepared by oxidation of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl, commonly referred to as [TEMPO]. A less expensive analogue is Bobbitt's salt. | 0 | Theoretical and Fundamental Chemistry |
Zymology, also known as zymurgy, is an applied science that studies the biochemical process of fermentation and its practical uses. Common topics include the selection of fermenting yeast and bacteria species and their use in brewing, wine making, fermenting milk, and the making of other fermented foods. | 1 | Applied and Interdisciplinary Chemistry |
Ligand-gated ion channels are likely to be the major site at which anaesthetic agents and ethanol have their effects, although unequivocal evidence of this is yet to be established. In particular, the GABA and NMDA receptors are affected by anaesthetic agents at concentrations similar to those used in clinical anaesthesia.
By understanding the mechanism and exploring the chemical/biological/physical component that could function on those receptors, more and more clinical applications are proven by preliminary experiments or FDA. Memantine is approved by the U.S. F.D.A and the European Medicines Agency for the treatment of moderate-to-severe Alzheimers disease, and has now received a limited recommendation by the UKs National Institute for Health and Care Excellence for patients who fail other treatment options. Agomelatine, is a type of drug that acts on a dual melatonergic-serotonergic pathway, which have shown its efficacy in the treatment of anxious depression during clinical trials, study also suggests the efficacy in the treatment of atypical and melancholic depression. | 1 | Applied and Interdisciplinary Chemistry |
Let and be two graphs. Graph is a sub-graph of graph (written as ) if and . If and contains all of the edges with , then is an induced sub-graph of . We call and isomorphic (written as ), if there exists a bijection (one-to-one correspondence) with for all . The mapping is called an isomorphism between and .
When and there exists an isomorphism between the sub-graph and a graph , this mapping represents an appearance of in . The number of appearances of graph in is called the frequency of in . A graph is called recurrent (or frequent) in when its frequency is above a predefined threshold or cut-off value. We use terms pattern and frequent sub-graph in this review interchangeably. There is an ensemble of random graphs corresponding to the null-model associated to . We should choose random graphs uniformly from and calculate the frequency for a particular frequent sub-graph in . If the frequency of in is higher than its arithmetic mean frequency in random graphs , where , we call this recurrent pattern significant and hence treat as a network motif for . For a small graph , the network , and a set of randomized networks , where , the Z-score of the frequency of is given by
where and stand for the mean and standard deviation of the frequency in set , respectively. The larger the , the more significant is the sub-graph as a motif. Alternatively, another measurement in statistical hypothesis testing that can be considered in motif detection is the p-value, given as the probability of (as its null-hypothesis), where indicates the frequency of G in a randomized network. A sub-graph with p-value less than a threshold (commonly 0.01 or 0.05) will be treated as a significant pattern. The p'-value for the frequency of is defined as
where indicates the number of randomized networks, is defined over an ensemble of randomized networks, and the Kronecker delta function is one if the condition holds. The concentration of a particular n-size sub-graph in network refers to the ratio of the sub-graph appearance in the network to the total n-size non-isomorphic sub-graphs' frequencies, which is formulated by
where index is defined over the set of all non-isomorphic n-size graphs. Another statistical measurement is defined for evaluating network motifs, but it is rarely used in known algorithms. This measurement is introduced by Picard et al. in 2008 and used the Poisson distribution, rather than the Gaussian normal distribution that is implicitly being used above.
In addition, three specific concepts of sub-graph frequency have been proposed. As the figure illustrates, the first frequency concept considers all matches of a graph in original network. This definition is similar to what we have introduced above. The second concept is defined as the maximum number of edge-disjoint instances of a given graph in original network. And finally, the frequency concept entails matches with disjoint edges and nodes. Therefore, the two concepts and restrict the usage of elements of the graph, and as can be inferred, the frequency of a sub-graph declines by imposing restrictions on network element usage. As a result, a network motif detection algorithm would pass over more candidate sub-graphs if we insist on frequency concepts and . | 1 | Applied and Interdisciplinary Chemistry |
(Also see: Eyespot apparatus)
*Channelrhodopsin: in unicellular algae, mediates phototaxis
*Chlamyopsin and volvoxopsin
*Flavoproteins | 1 | Applied and Interdisciplinary Chemistry |
The conjugation machinery of some bacteria (and archaeal flagella) is capable of transporting both DNA and proteins. It was discovered in Agrobacterium tumefaciens, which uses this system to introduce the Ti plasmid and proteins into the host, which develops the crown gall (tumor). The VirB complex of Agrobacterium tumefaciens is the prototypic system.
In the nitrogen-fixing Rhizobia, conjugative elements naturally engage in inter-kingdom conjugation. Such elements as the Agrobacterium Ti or Ri plasmids contain elements that can transfer to plant cells. Transferred genes enter the plant cell nucleus and effectively transform the plant cells into factories for the production of opines, which the bacteria use as carbon and energy sources. Infected plant cells form crown gall or root tumors. The Ti and Ri plasmids are thus endosymbionts of the bacteria, which are in turn endosymbionts (or parasites) of the infected plant.
The Ti and Ri plasmids are themselves conjugative. Ti and Ri transfer between bacteria uses an independent system (the tra, or transfer, operon) from that for inter-kingdom transfer (the vir, or virulence, operon). Such transfer creates virulent strains from previously avirulent Agrobacteria. | 1 | Applied and Interdisciplinary Chemistry |
Trifluoromethyl sulfone (PhSOCF) and trifluoromethyl sulfoxide (PhSOCF) can be used for trifluoromethylations of electrophiles | 0 | Theoretical and Fundamental Chemistry |
Circa 1925, the periodic table changed by shifting some Reihen (series) to the right, into an extra set of columns (groups). The original groups I–VII were repeated, distinguished by adding "A" and "B". Group VIII (with three columns) remained sole.
Thus, Reihen 4 and 5 were shifted, and together formed new period 4 with groups IA–VIIA, VIII, IB–VIIB. | 1 | Applied and Interdisciplinary Chemistry |
A glow-discharge device (GD) serves as a versatile source, as it can simultaneously introduce and atomize the sample. The glow discharge occurs in a low-pressure argon gas atmosphere between 1 and 10 torr. In this atmosphere lies a pair of electrodes applying a DC voltage of 250 to 1000 V to break down the argon gas into positively charged ions and electrons. These ions, under the influence of the electric field, are accelerated into the cathode surface containing the sample, bombarding the sample and causing neutral sample atom ejection through the process known as sputtering. The atomic vapor produced by this discharge is composed of ions, ground state atoms, and fraction of excited atoms. When the excited atoms relax back into their ground state, a low-intensity glow is emitted, giving the technique its name.
The requirement for samples of glow discharge atomizers is that they are electrical conductors. Consequently, atomizers are most commonly used in the analysis of metals and other conducting samples. However, with proper modifications, it can be utilized to analyze liquid samples as well as nonconducting materials by mixing them with a conductor (e.g. graphite). | 0 | Theoretical and Fundamental Chemistry |
A Living Machine is a form of ecological sewage treatment based on fixed-film ecology.
The Living Machine system was commercialized and is marketed by Living Machine Systems, L3C, a corporation based in Charlottesville, Va, USA. | 1 | Applied and Interdisciplinary Chemistry |
In the science of fluid flow, Stokes paradox is the phenomenon that there can be no creeping flow of a fluid around a disk in two dimensions; or, equivalently, the fact there is no non-trivial steady-state solution for the Stokes equations around an infinitely long cylinder. This is opposed to the 3-dimensional case, where Stokes method provides a solution to the problem of flow around a sphere.
Stokes' paradox was resolved by Carl Wilhelm Oseen in 1910, by introducing the Oseen equations which improve upon the Stokes equations – by adding convective acceleration. | 1 | Applied and Interdisciplinary Chemistry |
The solvent used in substitution reactions inherently determines the nucleophilicity of the nucleophile; this fact has become increasingly more apparent as more reactions are performed in the gas phase.
As such, solvent conditions significantly affect the performance of a reaction with certain solvent conditions favoring one reaction mechanism over another. For S1 reactions the solvents ability to stabilize the intermediate carbocation is of direct importance to its viability as a suitable solvent. The ability of polar solvents to increase the rate of S1 reactions is a result of the polar solvents solvating the reactant intermediate species, i.e., the carbocation, thereby decreasing the intermediate energy relative to the starting material. The following table shows the relative solvolysis rates of tert-butyl chloride with acetic acid (CHCOH), methanol (CHOH), and water (HO).
The case for S2 reactions is quite different, as the lack of solvation on the nucleophile increases the rate of an S2 reaction. In either case (S1 or S2), the ability to either stabilize the transition state (S1) or destabilize the reactant starting material (S2) acts to decrease the ΔG and thereby increase the rate of the reaction. This relationship is according to the equation ΔG = –RT ln K (Gibbs free energy). The rate equation for S2 reactions are bimolecular being first order in Nucleophile and first order in Reagent. The determining factor when both S2 and S1 reaction mechanisms are viable is the strength of the Nucleophile. Nuclephilicity and basicity are linked and the more nucleophilic a molecule becomes the greater said nucleophile's basicity. This increase in basicity causes problems for S2 reaction mechanisms when the solvent of choice is protic. Protic solvents react with strong nucleophiles with good basic character in an acid/base fashion, thus decreasing or removing the nucleophilic nature of the nucleophile. The following table shows the effect of solvent polarity on the relative reaction rates of the S2 reaction of 1-bromobutane with azide (N). There is a noticeable increase in reaction rate when changing from a protic solvent to an aprotic solvent. This difference arises from acid/base reactions between protic solvents (not aprotic solvents) and strong nucleophiles. While it is true that steric effects also affect the relative reaction rates, however, for demonstration of principle for solvent polarity on S2 reaction rates, steric effects may be neglected.
A comparison of S1 to S2 reactions is to the right. On the left is an S1 reaction coordinate diagram. Note the decrease in ΔG for the polar-solvent reaction conditions. This arises from the fact that polar solvents stabilize the formation of the carbocation intermediate to a greater extent than the non-polar-solvent conditions. This is apparent in the ΔE, ΔΔG. On the right is an S2 reaction coordinate diagram. Note the decreased ΔG for the non-polar-solvent reaction conditions. Polar solvents stabilize the reactants to a greater extent than the non-polar-solvent conditions by solvating the negative charge on the nucleophile, making it less available to react with the electrophile. | 0 | Theoretical and Fundamental Chemistry |
Nicasius le Febure, a.k.a. Nicolas le Febure or Nicasius le Fevre or Nicolas le Fèvre (1615 - 1669), was a French chemist and alchemist who was appointed to positions by both French and English royalty. | 1 | Applied and Interdisciplinary Chemistry |
In molecular biology and genetics, GC-content (or guanine-cytosine content) is the percentage of nitrogenous bases in a DNA or RNA molecule that are either guanine (G) or cytosine (C). This measure indicates the proportion of G and C bases out of an implied four total bases, also including adenine and thymine in DNA and adenine and uracil in RNA.
GC-content may be given for a certain fragment of DNA or RNA or for an entire genome. When it refers to a fragment, it may denote the GC-content of an individual gene or section of a gene (domain), a group of genes or gene clusters, a non-coding region, or a synthetic oligonucleotide such as a primer. | 1 | Applied and Interdisciplinary Chemistry |
Transcriptome instability is a genome-wide, pre-mRNA splicing-related characteristic of certain cancers. In general, pre-mRNA splicing is dysregulated in a high proportion of cancerous cells. For certain types of cancer, like in colorectal and prostate, the number of splicing errors per cancer has been shown to vary greatly between individual cancers, a phenomenon referred to as transcriptome instability. Transcriptome instability correlates significantly with reduced expression level of splicing factor genes. Mutation of DNMT3A contributes to development of hematologic malignancies, and DNMT3A-mutated cell lines exhibit transcriptome instability as compared to their isogenic wildtype counterparts. | 1 | Applied and Interdisciplinary Chemistry |
Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. "Nominal" refers to pipe in non-specific terms and identifies the diameter of the hole with a non-dimensional number (for example – 2-inch nominal steel pipe" consists of many varieties of steel pipe with the only criterion being a outside diameter). Specific pipe is identified by pipe diameter and another non-dimensional number for wall thickness referred to as the Schedule (Sched. or Sch., for example – "2-inch diameter pipe, Schedule 40"). NPS is often incorrectly called National Pipe Size, due to confusion with the American standard for pipe threads, "national pipe straight", which also abbreviates as "NPS". The European and international designation equivalent to NPS is DN (diamètre nominal/nominal diameter/Nennweite), in which sizes are measured in millimetres, see ISO 6708. The term NB (nominal bore) is also frequently used interchangeably with DN.
In March 1927 the American Standards Association authorized a committee to standardize the dimensions of wrought steel and wrought iron pipe and tubing. At that time only a small selection of wall thicknesses were in use: standard weight (STD), extra-strong (XS), and double extra-strong (XXS), based on the iron pipe size (IPS) system of the day. However these three sizes did not fit all applications. Also, in 1939, it was hoped that the designations of STD, XS, and XXS would be phased out by schedule numbers, however those original terms are still in common use today (although sometimes referred to as standard, extra-heavy (XH), and double extra-heavy (XXH), respectively). Since the original schedules were created, there have been many revisions and additions to the tables of pipe sizes based on industry use and on standards from API, ASTM, and others.
Stainless steel pipes, which were coming into more common use in the mid 20th century, permitted the use of thinner pipe walls with much less risk of failure due to corrosion. By 1949 thinner schedules 5S and 10S, which were based on the pressure requirements modified to the nearest BWG number, had been created, and other "S" sizes followed later. Due to their thin walls, the smaller "S" sizes can not be threaded together according to ASME code, but must be fusion welded, brazed, roll grooved, or joined with press fittings. | 1 | Applied and Interdisciplinary Chemistry |
The synergy between the atmospheric concentration measurements, the knowledge of local ecosystem fluxes on the other hand, has shown effective in reducing the uncertainties on carbon assessments. However, in Europe, observatories are all managed differently for each country and data is not homogeneously processed.
The value added impact of the infrastructure allows an enhanced visibility and dissemination of European greenhouse gas data and products that are both long-term and carefully calibrated. ICOS meets the data needs of carbon cycle and climate researchers as well as those of politicians and the general public. ICOS serves as the backbone to users engaged in developing data assimilation models of greenhouse gas sources and sinks, namely reverse modelling, which allows the deduction of surface carbon flux pattern.
A common data centre, the ICOS Carbon Portal, provides free access to all ICOS data, as well as to links with inventory data, and outreach material. This portal allows the production of web based tools for the survey of sources and sinks in near real-time. ICOS delivers the information in near real-time with a quantification of the uncertainty associated with the results due to the use of several different models using different methodologies.
ICOS enables Europe to be a key global player for in-situ observations of greenhouse gases, data processing and user-friendly access to data products for validation of remote sensing products, scientific assessments, modelling and data assimilation. | 1 | Applied and Interdisciplinary Chemistry |
Following 2D SDS PAGE the proteins can be transferred to a polyvinylidene difluoride (PVDF) blotting membrane for further analysis. Edman degradations can be performed directly from a PVDF membrane. N-terminal residue sequencing resulting in five to ten amino acid may be sufficient to identify a Protein of Interest (POI). | 0 | Theoretical and Fundamental Chemistry |
In crystallography, the dyakis dodecahedron only exists in one crystal, which is pyrite. Pyrite has other forms other than the dyakis dodecahedron, including tetrahedra, octahedra, cubes and pyritohedra. Though the cube and octahedron are in the cubic crystal system, the dyakis dodecahedron and the pyritohedon are in the isometric crystal system and the tetrahedron is in the tetrahedral crystal system. Though the dyakis dodecahedron has 3-fold axes like the pyritohedron and cube, it doesn't have 4-fold axes but it does have order-4 vertices, as when the dyakis dodecahedron is rotated 90 or 270° along an order-4 vertex, it is not the same as before, because the order-4 vertices act as 2-fold axes, as when they are rotated a full turn or 180°, the polyhedron looks the same as before. | 0 | Theoretical and Fundamental Chemistry |
Photosynthesis, plant water transport (xylem) and gas exchange are regulated by stomatal function which is important in the functioning of plants.
Stomata are responsive to light with blue light being almost 10 times as effective as red light in causing stomatal response. Research suggests this is because the light response of stomata to blue light is independent of other leaf components like chlorophyll. Guard cell protoplasts swell under blue light provided there is sufficient availability of potassium. Multiple studies have found support that increasing potassium concentrations may increase stomatal opening in the mornings, before the photosynthesis process starts, but that later in the day sucrose plays a larger role in regulating stomatal opening. Zeaxanthin in guard cells acts as a blue light photoreceptor which mediates the stomatal opening. The effect of blue light on guard cells is reversed by green light, which isomerizes zeaxanthin.
Stomatal density and aperture (length of stomata) varies under a number of environmental factors such as atmospheric CO concentration, light intensity, air temperature and photoperiod (daytime duration).
Decreasing stomatal density is one way plants have responded to the increase in concentration of atmospheric CO ([CO]). Although changes in [CO] response is the least understood mechanistically, this stomatal response has begun to plateau where it is soon expected to impact transpiration and photosynthesis processes in plants.
Drought inhibits stomatal opening, but research on soybeans suggests moderate drought does not have a significant effect on stomatal closure of its leaves. There are different mechanisms of stomatal closure. Low humidity stresses guard cells causing turgor loss, termed hydropassive closure. Hydroactive closure is contrasted as the whole leaf affected by drought stress, believed to be most likely triggered by abscisic acid. | 0 | Theoretical and Fundamental Chemistry |
One of the most critical steps in the SELEX procedure is obtaining single stranded DNA (ssDNA) after the PCR amplification step. This will serve as input for the next cycle so it is of vital importance that all the DNA is single stranded and as little as possible is lost. Because of the relative simplicity, one of the most used methods is using biotinylated reverse primers in the amplification step, after which the complementary strands can be bound to a resin followed by elution of the other strand with lye. Another method is asymmetric PCR, where the amplification step is performed with an excess of forward primer and very little reverse primer, which leads to the production of more of the desired strand. A drawback of this method is that the product should be purified from double stranded DNA (dsDNA) and other left-over material from the PCR reaction. Enzymatic degradation of the unwanted strand can be performed by tagging this strand using a phosphate-probed primer, as it is recognized by enzymes such as Lambda exonuclease. These enzymes then selectively degrade the phosphate tagged strand leaving the complementary strand intact. All of these methods recover approximately 50 to 70% of the DNA. For a detailed comparison refer to the article by Svobodová et al. where these, and other, methods are experimentally compared. In classical SELEX, the process of randomized single stranded library generation, target incubation, and binding sequence elution and amplification described above are repeated until the vast majority of the retained pool consists of target binding sequences, though there are modifications and additions to the procedure that are often used, which are discussed below. | 1 | Applied and Interdisciplinary Chemistry |
An excimer (originally short for excited dimer) is a short-lived polyatomic molecule formed from two species that do not form a stable molecule in the ground state. In this case, formation of molecules is possible only if such atom is in an electronic excited state. Heteronuclear molecules and molecules that have more than two species are also called exciplex molecules (originally short for excited complex). Excimers are often diatomic and are composed of two atoms or molecules that would not bond if both were in the ground state. The lifetime of an excimer is very short, on the order of nanoseconds. | 0 | Theoretical and Fundamental Chemistry |
Lisinopril is a medication belonging to the drug class of angiotensin-converting enzyme (ACE) inhibitors and is used to treat hypertension (high blood pressure), heart failure, and heart attacks. For high blood pressure it is usually a first-line treatment. It is also used to prevent kidney problems in people with diabetes mellitus. Lisinopril is taken orally (swallowed by mouth). Full effect may take up to four weeks to occur.
Common side effects include headache, dizziness, feeling tired, cough, nausea, and rash. Serious side effects may include low blood pressure, liver problems, hyperkalemia (high blood potassium), and angioedema. Use is not recommended during the entire duration of pregnancy as it may harm the baby. Lisinopril works by inhibiting the renin–angiotensin–aldosterone system.
Lisinopril was patented in 1978 and approved for medical use in the United States in 1987. It is available as a generic medication. In 2021, it was the fourth most commonly prescribed medication in the United States, with more than 88million prescriptions. In July 2016, an oral solution formulation of lisinopril was approved for use in the United States. | 0 | Theoretical and Fundamental Chemistry |
Upon treatment of ortho-carboranes with organolithium reagents such as n-Butyllithium, the CH vertices of the carborane cage can be deprotonated, affording the dilithiated ortho-carborane cage. Taking advantage of this more active carbon-lithium bond, the metalated carborane cages can then be treated with copper(I) chloride while in organic solvents, resulting in a copper-mediated carbon-carbon coupling reaction of the carborane cages. The copper salt is needed to avoid unwanted carbon-boron and boron-boron coupling reactions. The reaction mixture is allowed to stir at room temperature for two days, forming a copper-metalated carborane cage. Finally, the mixture is treated with 3M hydrochloric acid to quench the reaction process. The crude product is then purified via column chromatography and affords one half-equivalent of the carbon-carbon linked dimer of the original ortho-carborane in high yields. Worth noting is the effect of donating solvents on the yields of the reactions, as yields in solvents such as tetrahydrofuran and diethyl ether afford product in greatly decreased yields. | 0 | Theoretical and Fundamental Chemistry |
The Vinland Map is a document that appears to be a 15th-century mappa mundi and which shows a landmass in the Atlantic Ocean, directly south-west of Greenland, labelled Vinlanda Insula ("Isle of Vinland"). It first came to light in 1957 and was acquired by Yale University in 1964. The map's authenticity would have established the awareness of a part of the American continent by European cartographers, before the voyages of Christopher Columbus. McCrone, already reputed for his expertise in authenticating ancient documents and works of art, was asked by Yale to analyze the map in 1972. In 1974, he published evidence that the ink of the map contained synthetic anatase (a form of titanium dioxide), a substance not used as a pigment until the 1920s. According to McCrone, the anatase is present in the yellow ink that the forger used to simulate the natural discoloration that appears over long periods of time around lines drawn on parchment in medieval iron gall ink.
McCrones work on the Vinland Map led to a protracted controversy, with other researchers continuing to argue for the documents authenticity and discounting the presence of titanium as insignificant. In 2021, Raymond Clemens, the curator of early books and manuscripts at Yale's Beinecke Rare Book & Manuscript Library where the map is housed, declared that it had been conclusively shown to be a fake. That judgment was largely based on the presence of synthetic anatase in the ink, as first identified by McCrone. | 0 | Theoretical and Fundamental Chemistry |
The German Clay Group (DTTG) awards the Gerhard Lagaly Award, to "internationally excellent scientists with outstanding original research in the field of clay mineralogy."
The award is designated after the internationally highly recognized clay scientist and the distinguished member of the DTTG, Professor Dr. Dr. Gerhard Lagaly.
The prize was first awarded in 2014 to Prof. Dr. Juraj Bujdák (Comenius University Bratislava). In 2016, the prize went to Dr. habil. Sabine Petit (Université de Poitiers). The recipient of the 2018 prize was Dr. Stephan Kaufhold (BGR Hannover). | 0 | Theoretical and Fundamental Chemistry |
One of the most notable surveillance projects was the Hazardous Substances Emergency Events Surveillance (HSEES) program, which lasted from 1990 to 2009. ATSDR partnered with 15 states to collect information for HSEES in order to track, report, and study chemical spills. The information in the HSEES system was used to plan for emergency events involving hazardous substances (including terrorist attacks). States also used the information to develop policies and programs to strengthen public health and reduce illnesses and deaths that can result from exposure to hazardous substances. For example, states used HSEES data to support legislation addressing the problem of hazardous chemicals at illegal methamphetamine labs. Other states used HSEES data to implement programs designed to minimize exposure to hazardous chemicals and mercury at schools. More than 50 published studies were conducted using HSEES data. | 1 | Applied and Interdisciplinary Chemistry |
*AARS NM_001605 alanyl-tRNA synthetase
*AARS2 NM_020745 alanyl-tRNA synthetase 2, mitochondrial
*AARSD1 NM_001261434 alanyl-tRNA synthetase domain containing 1
*CARS NM_001751 cysteinyl-tRNA synthetase
*CARS2 NM_024537 cysteinyl-tRNA synthetase 2, mitochondrial (putative)
*DARS NM_001349 aspartyl-tRNA synthetase
*DARS2 NM_018122 aspartyl-tRNA synthetase 2, mitochondrial
*EARS2 NM_001083614 glutamyl-tRNA synthetase 2, mitochondrial
*FARS2 NM_006567 phenylalanyl-tRNA synthetase 2, mitochondrial
*FARSA NM_004461 phenylalanyl-tRNA synthetase, alpha subunit
*FARSB NM_005687 phenylalanyl-tRNA synthetase, beta subunit
*GARS NM_002047 glycyl-tRNA synthetase
*HARS NM_002109 histidyl-tRNA synthetase
*HARS2 NM_012208 histidyl-tRNA synthetase 2, mitochondrial
*IARS NM_002161 isoleucyl-tRNA synthetase
*IARS2 NM_018060 isoleucyl-tRNA synthetase 2, mitochondrial
*KARS NM_005548 Homo sapiens lysyl-tRNA synthetase (KARS), mRNA
*LARS2 NM_015340 isoleucyl-tRNA synthetase 2, mitochondrial
*MARS NM_004990 methionyl-tRNA synthetase
*MARS2 NM_138395 methionyl-tRNA synthetase 2, mitochondrial
*NARS NM_004539 asparaginyl-tRNA synthetase
*NARS2 NM_024678 asparaginyl-tRNA synthetase 2, mitochondrial (putative)
*QARS NM_005051 glutaminyl-tRNA synthetase
*RARS NM_002884 arginyl-tRNA synthetase
*RARS2 NM_020320 arginyl-tRNA synthetase 2, mitochondrial
*SARS NM_006513 Homo sapiens seryl-tRNA synthetase (SARS), mRNA
*TARS NM_152295 threonyl-tRNA synthetase
*VARS2 NM_020442 valyl-tRNA synthetase 2, mitochondrial
*WARS2 NM_015836 tryptophanyl tRNA synthetase 2, mitochondrial
*YARS NM_003680 Homo sapiens tyrosyl-tRNA synthetase (YARS), mRNA
*YARS2 NM_001040436 Homo sapiens tyrosyl-tRNA synthetase (YARS), mRNA mitochondrial | 1 | Applied and Interdisciplinary Chemistry |
The Lamb–Chaplygin dipole model is a mathematical description for a particular inviscid and steady dipolar vortex flow. It is a non-trivial solution to the two-dimensional Euler equations. The model is named after Horace Lamb and Sergey Alexeyevich Chaplygin, who independently discovered this flow structure. This dipole is the two-dimensional analogue of Hill's spherical vortex.
__TOC__ | 1 | Applied and Interdisciplinary Chemistry |
Angela Casini joined the École Polytechnique Fédérale de Lausanne as a Principal Investigator in 2008. She moved to the University of Groningen in 2011, where she was made a Rosalind Franklin Fellow. She was made a Chair of Medicinal Chemistry at Cardiff University in 2015, and has served as Director of Postgraduate Teaching from 2018. She spent 2016 as a Visiting Professor at the Technical University of Munich. | 0 | Theoretical and Fundamental Chemistry |
When the pipes have certain roughness , this factor must be taken in account when the Fanning friction factor is calculated. The relationship between pipe roughness and Fanning friction factor was developed by Haaland (1983) under flow conditions of
where
* is the roughness of the inner surface of the pipe (dimension of length)
* D is inner pipe diameter;
The Swamee–Jain equation is used to solve directly for the Darcy–Weisbach friction factor f for a full-flowing circular pipe. It is an approximation of the implicit Colebrook–White equation. | 1 | Applied and Interdisciplinary Chemistry |
Fluorosulfonate, in organic chemistry, is a functional group that has the chemical formula F-SO-R, and typically is a very good leaving group. In organic chemistry, fluorosulfonate is different than fluorosulfate. In fluorosulfonates, sulfur atom is directly bonded to a non-oxygen atom such as carbon. In inorganic chemistry, fluorosulfonate is another term for fluorosulfate, the anion F-SO-O, the conjugate base of fluorosulfonic acid. They form a series of salts with metal and organic cations called fluorosulfates.
Organic (alkyl) fluorosulfonates are usually strong alkylation agents, similar to triflate esters (FC-SO-OR). But unlike the triflate group, the fluorosulfonate group is not stable against hydrolysis. Therefore, fluorosulfonate esters are less frequently used as alkylation agents than triflate esters. | 0 | Theoretical and Fundamental Chemistry |
Al-Wardi is the Director of the Collections Department at the National Museum of Oman. She was appointed to the role in 2019. She joined the museum in 2009 as Chief Curator during its construction and development. She is a specialist in historical metal-working, in particular in bronze and silver. She is an expert on the history of silversmithing, particularly in Oman, which has a historic tradition of women working as silversmiths, particularly in southern Oman in Dhofar. The project is a collaboration between Aude Mongiatti (British Museum), Fahmida Suleman (Royal Ontario Museum), Marcia Dorr and Al-Wardi. As part of this work she has studied the coinage that circulated in Oman and in particular its re-use into coin pendants. Al-Wardi has also worked on the Diba Hoard, an assemblage of stone vessels and bronze metalwork dating to 1200 - 300 BCE.
In 2013 she was a candidate on the British Museum's International Training Programme. She previously studied for a BA degree in Heritage and Cultural Studies from Curtin University (formally known as Western Australian Institute of Technology) in Perth. After graduation she worked at the Museum of Omani Heritage, developing training programmes and working on their heritage craft programme. In 2018 she was part of a UNESCO-hosted regional event in Kuwait, which focussed on the development of national museums. | 1 | Applied and Interdisciplinary Chemistry |
The Takehara copper refinery of the Mitsui Mining & Smelting Company Limited of Japan commissioned a BBOC in its precious metals department in 1993.
Prior to the installation of the BBOC, the Takehara refinery refined a mixture of copper and lead anode slimes in a three reverberatory furnaces (two operating and one being rebricked) in a process that had a cycle time of 104 hours for refining 6 t of bullion.
The reverberatory furnaces were replaced with a single BBOC with a charge capacity of 6 t of feed. The cycle time was reduced to 50 hours. The use of the BBOC reduced the energy consumption from 74 GJ/t to 27 GJ/t and also had better bismuth elimination than the reverberatory furnaces. | 1 | Applied and Interdisciplinary Chemistry |
Indirect catalysts may also act through surface sensitization of reactants, by which species sorbed to a surface become more susceptible to photodegradation. | 0 | Theoretical and Fundamental Chemistry |
The first sperm banks began as early as 1964 in Iowa, USA and Tokyo, Japan and were established for a medical therapeutic approach to support individuals who were infertile. As a result, over 1 million babies were born within 40 years.
Sperm banks provide the opportunity for individuals to have a child who otherwise would not be able to conceive naturally. This includes, but is not limited to, single women, same-sexed couples, and couples where one partner is infertile.
Where a sperm bank provides fertility services directly to a recipient woman, it may employ different methods of fertilization using donor sperm in order to optimize the chances of a pregnancy. Sperm banks do not provide a cure for infertility in individuals who produce non-viable sperm. Nevertheless, the increasing range of services available through sperm banks enables people to have choices over challenges with reproduction.
Individuals may choose an anonymous donor who will not be a part of family life, or they may choose known donors who may be contacted later in life by the donor children. People may choose to use a surrogate to bear their children, using eggs provided by the person and sperm from a donor. Sperm banks often provide services which enable an individual to have subsequent pregnancies by the same donor, but equally, people may choose to have children by a number of different donors. Sperm banks sometimes enable an individual to choose the sex of their child, enabling even greater control over the way families are planned. Sperm banks increasingly adopt a less formal approach to the provision of their services thereby enabling people to take a relaxed approach to their own individual requirements.
Men who donate semen through a sperm bank provide an opportunity for others who cannot have children on their own. Sperm donors may or may not have legal obligations or responsibilities to the child conceived through this route. Whether a donor is anonymous or not, this factor is important in allowing sperm banks to recruit sperm donors and to use their sperm to produce whatever number of pregnancies from each donor as are permitted where they operate, or alternatively, whatever number they decide.
In many parts of the world sperm banks are not allowed to be established or to operate. Where sperm banks are allowed to operate they are often controlled by local legislation which is primarily intended to protect the unborn child, but which may also provide a compromise between the conflicting views which surround their operation. A particular example of this is the control which is often placed on the number of children which a single donor may father and which may be designed to protect against consanguinity. However, such legislation usually cannot prevent a sperm bank from supplying donor sperm outside the jurisdiction in which it operates, and neither can it prevent sperm donors from donating elsewhere during their lives. There is an acute shortage of sperm donors in many parts of the world and there is obvious pressure from many quarters for donor sperm from those willing and able to provide it to be made available as safely and as freely as possible. | 1 | Applied and Interdisciplinary Chemistry |
It is common to describe where electrons reside as electron bands in bulk materials and electron orbitals in molecules. For the sake of expedience the following description will be described in molecular terms. When a photon excites a molecule, an electron in a ground state orbital can be excited to a higher energy orbital. This excited state leaves a vacancy in a ground state orbital that can be filled by an electron donor. It produces an electron in a high energy orbital which can be donated to an electron acceptor. In these respects a photoexcited molecule can act as a good oxidizing agent or a good reducing agent.
:Photoinduced oxidation
:[ML] + hν → [ML]*
:[ML]* + donor → [ML] + donor
:Photoinduced reduction
:[ML] + hν → [ML]*
:[ML]* + acceptor → [ML] + acceptor
The end result of both reactions is that an electron is delivered to an orbital that is higher in energy than where it previously resided. This is often described as a charge separated electron-hole pair when working with semiconductors.
In the absence of a proper electron donor or acceptor it is possible for such molecules to undergo ordinary fluorescence emission. The electron transfer is one form of photoquenching. | 0 | Theoretical and Fundamental Chemistry |
The CFL phase has several remarkable properties.
* It breaks chiral symmetry.
* It is a superfluid.
* It is an electromagnetic insulator, in which there is a "rotated" photon, containing a small admixture of one of the gluons.
* It has the same symmetries as sufficiently dense hyperonic matter.
There are several variants of the CFL phase, representing distortions of the pairing structure in response to external stresses such as a difference between the mass of the strange quark and the mass of the up and down quarks. | 0 | Theoretical and Fundamental Chemistry |
Casting processes simulation uses numerical methods to calculate cast component quality considering mold filling, solidification and cooling, and provides a quantitative prediction of casting mechanical properties, thermal stresses and distortion. Simulation accurately describes a cast component's quality up-front before production starts. The casting rigging can be designed with respect to the required component properties. This has benefits beyond a reduction in pre-production sampling, as the precise layout of the complete casting system also leads to energy, material, and tooling savings.
The software supports the user in component design, the determination of melting practice and casting methoding through to pattern and mold making, heat treatment, and finishing. This saves costs along the entire casting manufacturing route.
Casting process simulation was initially developed at universities starting from the early 70s, mainly in Europe and in the U.S., and is regarded as the most important innovation in casting technology over the last 50 years. Since the late 80s, commercial programs are available which make it possible for foundries to gain new insight into what is happening inside the mold or die during the casting process. | 1 | Applied and Interdisciplinary Chemistry |
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