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In some measures the size (a length dimension in the expression) can't be obtained, only calculated as a function of another dimensions and parameters. Illustrating below by the main cases.
;Weight-based (spheroidal) particle size: Weight-based particle size equals the diameter of the sphere that has the same weight as a given particle. Useful as hypothesis in centrifugation and decantation, or when the number of particles can be estimated (to obtain average particle's weight as sample weight divided by the number of particles in the sample). This formula is only valid when all particles have the same density.
:where
::: diameter of representative sphere
::: weight of particle
::: density of particle
::: gravitational constant
;Aerodynamic particle size: Hydrodynamic or aerodynamic particle size equals the diameter of the sphere that has the same drag coefficient as a given particle.
: Another complexity in defining particle size in a fluid medium appears for particles with sizes below a micrometre. When a particle becomes that small, the thickness of the interface layer becomes comparable with the particle size. As a result, the position of the particle surface becomes uncertain. There is a convention for placing this imaginary surface at a certain position suggested by Gibbs and presented in many books on interface and colloid science. | 0 | Theoretical and Fundamental Chemistry |
The nomenclature used for organosulfur compounds is often non-systematic. Sometimes persulfides are called hydrodisulfides to further avoid confusion with disulfides with the grouping R-S-S-R, by emphasizing the presence of an H at one end of a disulfide bond. | 0 | Theoretical and Fundamental Chemistry |
Thermal runaway describes a process that is accelerated by increased temperature, in turn releasing energy that further increases temperature. Thermal runaway occurs in situations where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a destructive result. It is a kind of uncontrolled positive feedback.
In chemistry (and chemical engineering), thermal runaway is associated with strongly exothermic reactions that are accelerated by temperature rise. In electrical engineering, thermal runaway is typically associated with increased current flow and power dissipation. Thermal runaway can occur in civil engineering, notably when the heat released by large amounts of curing concrete is not controlled. In astrophysics, runaway nuclear fusion reactions in stars can lead to nova and several types of supernova explosions, and also occur as a less dramatic event in the normal evolution of solar-mass stars, the "helium flash". | 1 | Applied and Interdisciplinary Chemistry |
Hilbert Spectroscopy uses Hilbert transforms to analyze broad spectrum signals from gigahertz to terahertz frequency radio. One suggested use is to quickly analyze liquids inside airport passenger luggage. | 0 | Theoretical and Fundamental Chemistry |
In Mendelian disorders of large effect, findings thus far suggest one or a very small number of variants within coding genes underlie the entire condition. Because of the severity of these disorders, the few causal variants are presumed to be extremely rare or novel in the population, and would be missed by any standard genotyping assay. Exome sequencing provides high coverage variant calls across coding regions, which are needed to separate true variants from noise. A successful model of Mendelian gene discovery involves the discovery of de novo variants using trio sequencing, where parents and proband are genotyped. | 1 | Applied and Interdisciplinary Chemistry |
An early example of a supported metal–metal bond is cyclopentadienyliron dicarbonyl dimer, [(CH)Fe(CO)]. In the predominant isomers of this complex, the two Fe centers are joined not only by an Fe–Fe bond, but also by bridging CO ligands. The related cyclopentadienylruthenium dicarbonyl dimer features an unsupported Ru–Ru bond. Many metal clusters contain several supported M–M bonds. Some examples are Fe(CO) and Co(CO). | 0 | Theoretical and Fundamental Chemistry |
The magnetostriction effect describes a property of ferromagnetic materials which causes them to change their shape when subjected to a magnetic field. Joule first reported observing the change in the length of ferromagnetic rods in 1842. | 0 | Theoretical and Fundamental Chemistry |
The period immediately after the 10th century marked the widespread application of several innovations in the field of mining and ore treatment: a shift to large-scale and better quality production. Medieval miners and metallurgists had to find solutions for the practical problems that limited former metal production, in order to meet the market demands for metals. This increased demand for metal was due to the population growth from the 11th to the 13th centuries. This growth had an impact on agriculture, trade, and building construction, including Gothic churches.
The main problem was the inefficient means for draining water out of shafts and tunnels in underground mining. This resulted in the flooding of mines which limited the extraction of ore to shallow depths close to the surface. The secondary problem was the separation of the metal-bearing minerals from the worthless material that surrounds it, or is closely mixed with it. There was, additionally, the difficulty of transporting the ore, which resulted in subsequently high costs.
The economic value of mining led to investment in the development of solutions to these problems, which had a distinctly positive impact on medieval metal output. This included innovations such as water power using waterwheels for powering draining engines, bellows, hammers, and the introduction of advanced types of furnaces.
These innovations were not adopted all at once or applied to all mines and smelting sites. Throughout the medieval period, these technical innovations, and traditional techniques coexisted. Their application depended on the time period and geographical region. Water power in medieval mining and metallurgy was introduced well before the 11th century, but it was only in the 11th century that it was widely applied. The introduction of the blast furnace, mostly for iron smelting, in all the established centers of metallurgy contributed to the quantitative and qualitative improvement of the metal output, making metallic iron available at a lower price.
In addition, cupellation, developed in the 8th century, was more often used for the refinement of lead-silver ores, to separate the silver from the lead (Bayley 2008). Parallel production with more than one technical method, and different treatment of ores would occur wherever multiple ores were present at one site. (Rehren et al. 1999).
Underground work in shafts, although limited in depth, was accomplished either by fire-setting for massive ore bodies or with iron tools for smaller scale extraction of limited veins. The sorting of base and precious metal ores was completed underground and they were transferred separately (Martinon-Torres & Rehren in press, b).
Permanent mining in Sweden proper begun in the High Middle Ages and did not spread to Finland until 1530 when the first iron mine began operations there. | 1 | Applied and Interdisciplinary Chemistry |
Each duplex sequencing read contains a fixed 5-nucleotide sequence (shown in figures in black) located upstream of the 12-nucleotide tag sequence. The reads are filtered if they do not have the expected 5-nucleotide sequence or have more than nine identical or ambiguous bases within each tag. The two 12-nucleotide tags at each end of the reads are combined and moved to the read header. Two families of reads are formed that originate from the two strands of DNA. One family contains reads with αβ header originating from strand 1 and the second contains reads with βα header originating from strand 2 (Figure 2). The reads are then trimmed by removing the fixed 5-base pair sequence and 4 error-prone nucleotides located at the sites of ligation and end repair. The remaining reads are assembled to consensus sequences using SSCS and DCS assemblies. | 1 | Applied and Interdisciplinary Chemistry |
A variety or organosulfur compounds occur in nature. Most abundant are the amino acids methionine, cysteine, and cystine. The vitamins biotin and thiamine, as well as lipoic acid contain sulfur heterocycles. Glutathione is the primary intracellular antioxidant. Penicillin and cephalosporin are life-saving antibiotics, derived from fungi. Gliotoxin is a sulfur-containing mycotoxin produced by several species of fungi under investigation as an antiviral agent. | 0 | Theoretical and Fundamental Chemistry |
Dr. Joseph Fried (July 21, 1914 – August 17, 2001) was a Polish-American organic chemist, member of the National Academy of Sciences and the American Academy of Arts and Sciences. He held 200 patents on chemical compounds, with 43 listing him as the sole holder. He was a professor of chemistry and biochemistry at the University of Chicago. Fried discovered fluorohydrocortisone, a chemical used to treat adrenal disorders. He was also director of the organic chemistry at the Squibb Institute.
His discoveries were instrumental to the creation of medications to treat inflammatory disorders including as arthritis, psoriasis, and various skin allergies.
National Academies Press called him "an outstanding organic chemist who made very special contributions to the field of medicine".
Professor Elias James Corey (Nobel laureate, 1990) had this to say of Fried: "He was an outstanding, highly creative scientist who straddled both the worlds of pharmaceutical research and academic science. He was one of my heroes, and I've always thought of him as a model scientist of great character and great human warmth." | 0 | Theoretical and Fundamental Chemistry |
In medicine, phosphonates and bisphosphonates are commonly used as inhibitors of enzymes which utilize phosphates and diphosphates as substrates. Most notably, these enzymes include those that produce the intermediates of cholesterol biosynthesis.
Phosphonate nucleotide analogues such as tenofovir, cidofovir and adefovir are critical antiviral medications, which in various pro-drug forms are used for the treatment of HIV, hepatitis B and others. | 0 | Theoretical and Fundamental Chemistry |
The history of molecular biology begins in the 1930s with the convergence of various, previously distinct biological and physical disciplines: biochemistry, genetics, microbiology, virology and physics. With the hope of understanding life at its most fundamental level, numerous physicists and chemists also took an interest in what would become molecular biology.
In its modern sense, molecular biology attempts to explain the phenomena of life starting from the macromolecular properties that generate them. Two categories of macromolecules in particular are the focus of the molecular biologist: 1) nucleic acids, among which the most famous is deoxyribonucleic acid (or DNA), the constituent of genes, and 2) proteins, which are the active agents of living organisms. One definition of the scope of molecular biology therefore is to characterize the structure, function and relationships between these two types of macromolecules. This relatively limited definition will suffice to allow us to establish a date for the so-called "molecular revolution", or at least to establish a chronology of its most fundamental developments. | 1 | Applied and Interdisciplinary Chemistry |
Propionyl-CoA has can have many adverse and toxic affects on different species, including bacterium. For example, inhibition of pyruvate dehydrogenase by an accumulation of propionyl-CoA in Rhodobacter sphaeroides can prove deadly. Furthermore, as with E. coli, an influx of propionyl-CoA in Myobacterial species can result in toxicity if not dealt with immediately. This toxicity is caused by a pathway involving the lipids that form the bacterial cell wall. Using esterification of long-chain fatty acids, excess propionyl-CoA can be sequestered and stored in the lipid, triacylglycerol (TAG), leading to regulation of elevated propionyl-CoA levels. Such a process of methyl branching of the fatty acids causes them to act as sinks for accumulating propion | 1 | Applied and Interdisciplinary Chemistry |
I is a gamma emitter with a long half-life of 59.4 days (the longest of all radioiodines used in medicine). Iodine-123 is preferred for imaging, so I-125 is used diagnostically only when the test requires a longer period to prepare the radiopharmaceutical and trace it, such as a fibrinogen scan to diagnose clotting. I-125's gamma radiation is of medium penetration, making it more useful as a therapeutic isotope for brachytherapy implant of radioisotope capsules for local treatment of cancers. | 0 | Theoretical and Fundamental Chemistry |
Because of its potent biological activities, kendomycin has attracted interest as a target of total synthesis. The first total synthesis of kendomycin was accomplished by Lee and Yuan in 2004. The total number of syntheses stands at 6. | 0 | Theoretical and Fundamental Chemistry |
Yuri Zhdanov was born on August 20, 1919, in Tver. He graduated from Moscow State University in 1941 with a degree in organic chemistry and served with the Red Army during World War II. He received a Ph.D. in 1948.
In 1947, he was appointed head of the Central Committees Science Department. As head of the department, he publicly criticized the scientific theories of Trofim Lysenko at a meeting with party propagandists and was subsequently rebuked by Joseph Stalin at a Politburo meeting ("Dont you know that our entire agriculture depends on Lysenko?").
He married Svetlana Alliluyeva in the spring of 1949 "as a matter of hard common sense but without any special love or affection". Joseph Stalin respected the Zhdanov family and had always hoped the two families would be linked in marriage. They soon divorced in 1952. They had a daughter Yekaterina in 1950.
He joined Rostov State University in 1953, becoming a member of the Soviet Academy of Sciences and eventually Rector of the University. He was the author of numerous papers on organic chemistry.
In 1950 as the member of Soviet political leadership Zhdanov took active role in the implementation of the national policy of antisemitism. In his later year while being the Rector of Rostov State University and the Chair of the North-Caucasian Scientific Center of Higher Education he established the atmosphere of ethnic and religious tolerance. At that time most Soviet colleges and universities had severe quota on Jewish students and faculty. Many Jewish students from different regions of the Soviet Union were coming to Rostov-on-Don knowing that they would be admitted to local colleges and university. Most colleges and universities of the Rostov-on-Don region under the leadership of Zhdanov employed Jewish faculty and staff. Three out of five scientific research institutes of Rostov State University were headed by Jews.
He died on 19 December 2006 in Rostov-on-Don. | 0 | Theoretical and Fundamental Chemistry |
Diebold was born on 12 December 1961 in Kapfenberg, Austria. She spent much of her high school years reading, skiing, and agonizing over what to major in at the university. She ultimately settled on engineering physics, an area with good job prospects that was also general enough to accommodate a variety of future directions. After completing her diploma in engineering physics (TU Vienna, 1986), she became increasingly enthusiastic about experimental physics while working on her master's thesis, and ultimately completed a Doctor of Technology (Dr. techn.) in this area with Prof. Peter Varga (TU Vienna, 1990). | 0 | Theoretical and Fundamental Chemistry |
Thiiranes occur very rarely in nature and are of no significance medicinally.
Very few commercial applications exist, although the polymerization of episulfide has been reported. | 0 | Theoretical and Fundamental Chemistry |
Attempts at standardized temperature measurement prior to the 17th century were crude at best. For instance in 170 AD, physician Claudius Galenus mixed equal portions of ice and boiling water to create a "neutral" temperature standard. The modern scientific field has its origins in the works by Florentine scientists in the 1600s including Galileo constructing devices able to measure relative change in temperature, but subject also to confounding with atmospheric pressure changes. These early devices were called thermoscopes. The first sealed thermometer was constructed in 1654 by the Grand Duke of Tuscany, Ferdinand II. The development of todays thermometers and temperature scales began in the early 18th century, when Gabriel Fahrenheit produced a mercury thermometer and scale, both developed by Ole Christensen Rømer. Fahrenheits scale is still in use, alongside the Celsius and Kelvin scales. | 0 | Theoretical and Fundamental Chemistry |
Lecoq de Boisbaudran was a member of a noble family of Huguenots from the French provinces of Poitou and Angoumois. The Huguenots were French Protestants, a population that was devastated during the French Wars of Religion (1561–1598). The Edict of Nantes (1598) granted substantial civil rights to the Huguenots even though it maintained Catholicism's position as the established religion of France. The Edict of Nantes was overturned by the Edict of Fontainebleau (1685), which officially sanctioned persecution of Protestants. The Lecoq de Boisbaudran family was of considerable fortune until the revocation of the Edict of Nantes, after which much of their property was confiscated and sold.
Paul-Émile (Francois) Lecoq de Boisbaudran was a son of Paul Lecoq de Boisbaudran (1801–1870) and his wife Anne Louise. Paul Lecoq de Boisbaudran established a successful wine business in Cognac, benefiting from the hard work of the entire family including young Paul-Émile.
Anne Louise Lecoq de Boisbaudran was well educated and taught her son Paul-Émile history and foreign languages, including English. He obtained the syllabus of the École Polytechnique, and he studied the books assigned in its courses. In this way, he was self-taught as a scientist. As such, de Boisbaudran is an example of an autodidact. With the support of his family, he assembled a modest chemical laboratory on the second floor of their home on the Rue de Lusignan. In this laboratory, he repeated the experiments that he had studied in books. Through these experiments, he developed his theories of spectroscopy and made most of his discoveries, including the isolation of gallium.
Lecoq de Boisbaudran married Jeannette Nadault-Valette (1852–1926) on 27 December 1897. They had no children. He developed ankylosis of the joints, and failing health hindered his work after 1895. He died in 1912, at the age of 74. | 1 | Applied and Interdisciplinary Chemistry |
Magnesium can affect muscle relaxation through direct action on cell membranes. Mg ions close certain types of calcium channels, which conduct positively charged calcium ions into neurons. With an excess of magnesium, more channels will be blocked and nerve cells activity will decrease. | 1 | Applied and Interdisciplinary Chemistry |
5-Methylcytosine (5-mC) is a methylated form of the DNA base cytosine (see figure). 5-mC is an epigenetic marker found predominantly on cytosines within CpG dinucleotides, which consist of a cytosine is followed by a guanine reading in the 5′ to 3′ direction along the DNA strand (CpG sites). About 28 million CpG dinucleotides occur in the human genome. In most tissues of mammals, on average, 70% to 80% of CpG cytosines are methylated (forming 5-methyl-CpG, or 5-mCpG). Methylated cytosines within CpG sequences often occur in groups, called CpG islands. About 59% of promoter sequences have a CpG island while only about 6% of enhancer sequences have a CpG island. CpG islands constitute regulatory sequences, since if CpG islands are methylated in the promoter of a gene this can reduce or silence gene expression.
DNA methylation regulates gene expression through interaction with methyl binding domain (MBD) proteins, such as MeCP2, MBD1 and MBD2. These MBD proteins bind most strongly to highly methylated CpG islands. These MBD proteins have both a methyl-CpG-binding domain and a transcriptional repression domain. They bind to methylated DNA and guide or direct protein complexes with chromatin remodeling and/or histone modifying activity to methylated CpG islands. MBD proteins generally repress local chromatin by means such as catalyzing the introduction of repressive histone marks or creating an overall repressive chromatin environment through nucleosome remodeling and chromatin reorganization.
Transcription factors are proteins that bind to specific DNA sequences in order to regulate the expression of a given gene. The binding sequence for a transcription factor in DNA is usually about 10 or 11 nucleotides long. There are approximately 1,400 different transcription factors encoded in the human genome and they constitute about 6% of all human protein coding genes. About 94% of transcription factor binding sites that are associated with signal-responsive genes occur in enhancers while only about 6% of such sites occur in promoters.
EGR1 is a transcription factor important for regulation of methylation of CpG islands. An EGR1 transcription factor binding site is frequently located in enhancer or promoter sequences. There are about 12,000 binding sites for EGR1 in the mammalian genome and about half of EGR1 binding sites are located in promoters and half in enhancers. The binding of EGR1 to its target DNA binding site is insensitive to cytosine methylation in the DNA.
While only small amounts of EGR1 protein are detectable in cells that are un-stimulated, EGR1 translation into protein at one hour after stimulation is markedly elevated. Expression of EGR1 in various types of cells can be stimulated by growth factors, neurotransmitters, hormones, stress and injury. In the brain, when neurons are activated, EGR1 proteins are upregulated, and they bind to (recruit) pre-existing TET1 enzymes, which are highly expressed in neurons. TET enzymes can catalyze demethylation of 5-methylcytosine. When EGR1 transcription factors bring TET1 enzymes to EGR1 binding sites in promoters, the TET enzymes can demethylate the methylated CpG islands at those promoters. Upon demethylation, these promoters can then initiate transcription of their target genes. Hundreds of genes in neurons are differentially expressed after neuron activation through EGR1 recruitment of TET1 to methylated regulatory sequences in their promoters. | 1 | Applied and Interdisciplinary Chemistry |
All cells are coated in either glycoproteins or glycolipids, both of which help determine cell types. Lectins, or proteins that bind carbohydrates, can recognize specific oligosaccharides and provide useful information for cell recognition based on oligosaccharide binding.
An important example of oligosaccharide cell recognition is the role of glycolipids in determining blood types. The various blood types are distinguished by the glycan modification present on the surface of blood cells. These can be visualized using mass spectrometry. The oligosaccharides found on the A, B, and H antigen occur on the non-reducing ends of the oligosaccharide. The H antigen (which indicates an O blood type) serves as a precursor for the A and B antigen. Therefore, a person with A blood type will have the A antigen and H antigen present on the glycolipids of the red blood cell plasma membrane. A person with B blood type will have the B and H antigen present. A person with AB blood type will have A, B, and H antigens present. And finally, a person with O blood type will only have the H antigen present. This means all blood types have the H antigen, which explains why the O blood type is known as the "universal donor".
How do transport vesicles know the final destination of the protein that they are transporting?
Vesicles are directed by many ways, but the two main ways are:
# The sorting signals encoded in the amino acid sequence of the proteins.
# The Oligosaccharide attached to the protein.
The sorting signals are recognised by specific receptors that reside in the membranes or surface coats of budding vesicles, ensuring that the protein is transported to the appropriate destination. | 0 | Theoretical and Fundamental Chemistry |
PKM2 is enzyme pyruvate kinase M2 (PKM2) and a transcriptional coactivator of STAT1 responsible for the induction of the protein PDL-1 expression and its regulation in tumor and immune cells. In the lactate production, the upregulated PKM2 is required and it leads to its contribution in inflammatory response, organ injury and septic death As a consequence, the removal of PKM2 in myeloid cells, administration of anti-PD-L1 or supplementation with recombinant interleukin -1 (IL-7) eases the microbial clearance, inhibits T cell apoptosis, reduce multiple organ dysfunction and reduce septic death in Bmal1-deficient mice. | 1 | Applied and Interdisciplinary Chemistry |
In New Haven, the decommissioned English Station has a high concentration of PCB contamination due to the chemicals used in the running of the plant. This, along with asbestos contamination, has made cleaning and demolishing the abandoned site extremely difficult. The PCB contamination has spread to the soil, and to the river, where locals will sometimes fish unaware of the danger. | 1 | Applied and Interdisciplinary Chemistry |
Some materials may merge at the joint by diffusion. This may occur when the molecules of both materials are mobile and soluble in each other. This would be particularly effective with polymer chains where one end of the molecule diffuses into the other material. It is also the mechanism involved in sintering. When metal or ceramic powders are pressed together and heated, atoms diffuse from one particle to the next. This joins the particles into one.
Diffusive forces are somewhat like mechanical tethering at the molecular level. Diffusive bonding occurs when species from one surface penetrate into an adjacent surface while still being bound to the phase of their surface of origin. One instructive example is that of polymer-on-polymer surfaces. Diffusive bonding in polymer-on-polymer surfaces is the result of sections of polymer chains from one surface interdigitating with those of an adjacent surface. The freedom of movement of the polymers has a strong effect on their ability to interdigitate, and hence, on diffusive bonding. For example, cross-linked polymers are less capable of diffusion and interdigitation because they are bonded together at many points of contact, and are not free to twist into the adjacent surface. Uncrosslinked polymers (thermoplastics), on the other hand are freer to wander into the adjacent phase by extending tails and loops across the interface.
Another circumstance under which diffusive bonding occurs is “scission”. Chain scission is the cutting up of polymer chains, resulting in a higher concentration of distal tails. The heightened concentration of these chain ends gives rise to a heightened concentration of polymer tails extending across the interface. Scission is easily achieved by ultraviolet irradiation in the presence of oxygen gas, which suggests that adhesive devices employing diffusive bonding actually benefit from prolonged exposure to heat/light and air. The longer such a device is exposed to these conditions, the more tails are scissed and branch out across the interface.
Once across the interface, the tails and loops form whatever bonds are favorable. In the case of polymer-on-polymer surfaces, this means more van der Waals forces. While these may be brittle, they are quite strong when a large network of these bonds is formed. The outermost layer of each surface plays a crucial role in the adhesive properties of such interfaces, as even a tiny amount of interdigitation – as little as one or two tails of 1.25 angstrom length – can increase the van der Waals bonds by an order of magnitude. | 0 | Theoretical and Fundamental Chemistry |
A number of design techniques are used to counter the effects of Mach tuck.
On both conventional tailplane and canard foreplane configurations, the horizontal stabiliser may be made large and powerful enough to correct the large trim changes associated with Mach tuck. In place of the conventional elevator control surface, the whole stabiliser may be made moveable or "all-flying", sometimes called a stabilator. This both increases the authority of the stabilizer over a wider range of aircraft pitch, but also avoids the controllability issues associated with a separate elevator.
Aircraft that fly supersonic for long periods, such as Concorde, may compensate for Mach tuck by moving fuel between tanks in the fuselage to change the position of the centre of mass to match the changing location of the centre of pressure, thereby minimizing the amount of aerodynamic trim required.
A Mach trimmer is a device which varies the pitch trim automatically as a function of Mach number to oppose Mach tuck and maintain level flight. | 1 | Applied and Interdisciplinary Chemistry |
Pyroelectric fusion refers to the technique of using pyroelectric crystals to generate high strength electrostatic fields to accelerate deuterium ions (tritium might also be used someday) into a metal hydride target also containing deuterium (or tritium) with sufficient kinetic energy to cause these ions to undergo nuclear fusion. It was reported in April 2005 by a team at UCLA. The scientists used a pyroelectric crystal heated from −34 to 7 °C (−29 to 45 °F), combined with a tungsten needle to produce an electric field of about 25 gigavolts per meter to ionize and accelerate deuterium nuclei into an erbium deuteride target. Though the energy of the deuterium ions generated by the crystal has not been directly measured, the authors used 100 keV (a temperature of about 10 K) as an estimate in their modeling. At these energy levels, two deuterium nuclei can fuse to produce a helium-3 nucleus, a 2.45 MeV neutron and bremsstrahlung. Although it makes a useful neutron generator, the apparatus is not intended for power generation since it requires far more energy than it produces. | 0 | Theoretical and Fundamental Chemistry |
In specific acid catalysis, protonated solvent is the catalyst. The reaction rate is proportional to the concentration of the protonated solvent molecules SH. The acid catalyst itself (AH) only contributes to the rate acceleration by shifting the chemical equilibrium between solvent S and AH in favor of the SH species. This kind of catalysis is common for strong acids in polar solvents, such as water.
For example, in an aqueous buffer solution the reaction rate for reactants R depends on the pH of the system but not on the concentrations of different acids.
This type of chemical kinetics is observed when reactant R is in a fast equilibrium with its conjugate acid RH which proceeds to react slowly with R to the reaction product; for example, in the acid catalysed aldol reaction. | 0 | Theoretical and Fundamental Chemistry |
An interspecific semiochemical that is beneficial to both interacting organisms, the emitter and receiver, e.g. floral synomone of certain Bulbophyllum species (Orchidaceae) attracts fruit fly males (Tephritidae: Diptera) as pollinators. In this true mutualistic inter-relationship, both organisms gain benefits in their respective sexual reproduction - i.e. orchid flowers are pollinated and the Dacini fruit fly males are rewarded with a sex pheromone precursor or booster; and the floral synomones, also act as rewards to pollinators, are in the form of phenylpropanoids (e.g. methyl eugenol) and phenylbutanoids (e.g. raspberry ketone zingerone and anisyl acetone/a combination of the three phenylbutanoids. | 1 | Applied and Interdisciplinary Chemistry |
Having properly sized particles allow aggregate companies to create long-lasting roads and other products. Particle size analysis is also routinely conducted on bitumen emusions to predict their stability and their behavior. | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, two types of stream function are defined:
* The two-dimensional (or Lagrange) stream function, introduced by Joseph Louis Lagrange in 1781, is defined for incompressible (divergence-free), two-dimensional flows.
* The Stokes stream function, named after George Gabriel Stokes, is defined for incompressible, three-dimensional flows with axisymmetry.
The properties of stream functions make them useful for analyzing and graphically illustrating flows.
The remainder of this article describes the two-dimensional stream function. | 1 | Applied and Interdisciplinary Chemistry |
In 2020, evidence was provided that the cores of neutron stars with mass ~2M were likely composed of quark matter. Their result was based on neutron-star tidal deformability during a neutron star merger as measured by gravitational-wave observatories, leading to an estimate of star radius, combined with calculations of the equation of state relating the pressure and energy density of the star's core. The evidence was strongly suggestive but did not conclusively prove the existence of quark matter. | 0 | Theoretical and Fundamental Chemistry |
Little is known about an effective way to overcoming hyperacute rejection (HAR), which follows the activation of complement initiated by xenoreactive antibodies recognizing galactosyl-alpha1-3galatosyl (alpha-Gal) antigens on the donor epithelium. | 1 | Applied and Interdisciplinary Chemistry |
The crystallographic restriction theorem can be formulated in terms of isometries of Euclidean space. A set of isometries can form a group. By a discrete isometry group we will mean an isometry group that maps each point to a discrete subset of R, i.e. the orbit of any point is a set of isolated points. With this terminology, the crystallographic restriction theorem in two and three dimensions can be formulated as follows.
:For every discrete isometry group in two- and three-dimensional space which includes translations spanning the whole space, all isometries of finite order are of order 1, 2, 3, 4 or 6.
Isometries of order n include, but are not restricted to, n-fold rotations. The theorem also excludes S, S, D, and D (see point groups in three dimensions), even though they have 4- and 6-fold rotational symmetry only.
Rotational symmetry of any order about an axis is compatible with translational symmetry along that axis.
The result in the table above implies that for every discrete isometry group in four- and five-dimensional space which includes translations spanning the whole space, all isometries of finite order are of order 1, 2, 3, 4, 5, 6, 8, 10, or 12.
All isometries of finite order in six- and seven-dimensional space are of order 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 18, 20, 24 or 30 . | 0 | Theoretical and Fundamental Chemistry |
By 1982 the technology was sufficiently advanced for the technique to be called "high-speed" countercurrent chromatography (HSCCC). Peter Carmeci initially commercialized the PC Inc. Ito Multilayer Coil Separator/Extractor which utilized a single bobbin (onto which the coil is wound) and a counterbalance, plus a set of "flying leads" which are tubing that connect the bobbins. Dr. Walter Conway & others later evolved the bobbin design such that multiple coils, even coils of different tubing sizes, could be placed on the single bobbin. Edward Chou later evolved and commercialized a triple bobbin design as the Pharmatech CCC which had a de-twist mechanism for leads between the three bobbins. The Quattro CCC released in 1993 further evolved the commercially available instruments by utilizing a novel mirror image, twin bobbin design that did not need the de-twist mechanism of the Pharmatech between the multiple bobbins, so could still accommodate multiple bobbins on the same instrument. Hydrodynamic CCC are now available with up to 4 coils per instrument. These coils can be in PTFE, PEEK, PVDF, or stainless steel tubing. The 2, 3 or 4 coils can all be of the same bore to facilitate "2D" CCC (see below). The coils may be connected in series to lengthen the coil and increase the capacity, or the coils may be linked in parallel so that 2, 3, or 4 separations may be done simultaneously. The coils can also be of different sizes, on one instrument, ranging from 1 to 6 mm on one instrument, thus allowing a single instrument to optimize from mg to kilos per day. More recently instrument derivatives have been offered with rotating seals for various hydrodynamic CCC designs, instead of flying leads, either as custom or standard options. | 0 | Theoretical and Fundamental Chemistry |
Müllerian mimicry need not involve visual mimicry; it may employ any of the senses. For example, many snakes share the same auditory warning signals, forming an auditory Müllerian mimicry ring. More than one signal may be shared: snakes can make use of both auditory signals and warning coloration. | 1 | Applied and Interdisciplinary Chemistry |
In 1956, Tsung-Dao Lee and Chen Ning Yang noticed that there was no evidence that parity was conserved in weak interactions, and so they postulated that this symmetry may not be preserved by the weak force. They sketched the design for an experiment for testing conservation of parity in the laboratory. Later that year, Chien-Shiung Wu and coworkers conducted the Wu experiment showing an asymmetrical beta decay of cobalt-60| at cold temperatures that proved that parity is not conserved in beta decay. This surprising result overturned long-held assumptions about parity and the weak force. In recognition of their theoretical work, Lee and Yang were awarded the Nobel Prize for Physics in 1957. However Wu, who was female, was not awarded the Nobel prize. | 0 | Theoretical and Fundamental Chemistry |
Gadolin studied the relationship of heat to chemical changes, in particular, the ability of different substances to absorb heat (specific heat) and the absorption of heat during state changes (latent heat). This thermochemical work required extremely precise measurements. Gadolin published important papers on specific heat by 1784, and on the latent heat of steam in 1791. He demonstrated that the heat of ice was equal to the heat of snow, and published a standard set of heat tables. | 1 | Applied and Interdisciplinary Chemistry |
Transposable elements (transposons, TEs, jumping genes) are short strands of repetitive DNA that can self-replicate and translocate within the eukaryotic genome, and are generally perceived as parasitic in nature. Their transcription can lead to the production of dsRNAs (double-stranded RNAs), which resemble retroviruses transcripts. While most host cellular RNA has a singular, unpaired sense strand, dsRNA possesses sense and anti-sense transcripts paired together, and this difference in structure allows an host organism to detect dsRNA production, and thereby the presence of transposons. Plants lack distinct divisions between somatic cells and reproductive cells, and also have, generally, larger genomes than animals, making them an intriguing case-study kingdom to be used in attempting to better understand the epigenetics function of transposable elements. | 1 | Applied and Interdisciplinary Chemistry |
Modafinil, sold under the brand name Provigil among others, is a wakefulness-promoting medication used primarily to treat narcolepsy. Modafinil is also approved for stimulating wakefulness in people with sleep apnea and shift work sleep disorder. It is taken by mouth. Modafinil is not approved by the US Food and Drug Administration (FDA) for use in people under age 17.
Modafinil has potential for causing severe allergic reactions, mental (psychiatric) effects, hypersensitivity, adverse interactions with prescription drugs, and misuse or abuse. Modafinil may harm the fetus if taken during or two months prior to pregnancy.
While modafinil is used as a cognitive enhancer or "smart drug" among healthy individuals seeking improved focus and productivity, its use outside medical supervision raises concerns regarding potential misuse or abuse. Research on the cognitive enhancement effects of modafinil in non-sleep-deprived individuals has yielded mixed results, with some studies suggesting modest improvements in attention and executive functions, while others show no significant benefits or even a decline in cognitive functions. | 0 | Theoretical and Fundamental Chemistry |
In the isometric system, the most common types of twins are the Spinel Law (twin plane, parallel to an octahedron) <111>, where the twin axis is perpendicular to an octahedral face, and the Iron Cross <001>, which is the interpenetration of two pyritohedrons, a subtype of dodecahedron.
In the hexagonal system, calcite shows the contact twin laws {0001} and {0112}. Quartz shows the Brazil Law {1120}, and Dauphiné Law <0001>, which are penetration twins caused by transformation, and Japan Law {1122}, which is often caused by accidents during growth.
In the tetragonal system, cyclical contact twins are the most commonly observed type of twin, such as in rutile titanium dioxide and cassiterite tin oxide.
In the orthorhombic system, crystals usually twin on planes parallel to the prism face, where the most common is a {110} twin, which produces cyclical twins, such as in aragonite, chrysoberyl, and cerussite.
In the monoclinic system, twins occur most often on the planes {100} and {001} by the Manebach Law {001}, Carlsbad Law [001], Baveno Law {021} in orthoclase, and the Swallow Tail Twins (Manebach law) {001} in gypsum.
In the triclinic system, the most commonly twinned crystals are the feldspar minerals plagioclase and microcline. These minerals show the Albite and Pericline Laws.
The most common twin operations by crystal system are tabulated below. This list is not exhaustive, particularly for the crystal systems of lowest symmetry, such as the triclinic system. | 0 | Theoretical and Fundamental Chemistry |
Most branching phylogenies are thermophilic or hyperthermophilic, making it possible that the Last universal common ancestor (LUCA) and preceding lifeforms were similarly thermophilic. Hot springs are formed from the heating of groundwater by geothermal activity. This intersection allows for influxes of material from deep penetrating waters and from surface runoff that transports eroded continental sediments. Interconnected groundwater systems create a mechanism for distribution of life to wider area.
Mulkidjanian and co-authors argue that marine environments did not provide the ionic balance and composition universally found in cells, or the ions required by essential proteins and ribozymes, especially with respect to high K/Na ratio, Mn, Zn and phosphate concentrations. They argue that the only environments that mimic the needed conditions on Earth are hot springs similar to ones at Kamchatka. Mineral deposits in these environments under an anoxic atmosphere would have suitable pH (while current pools in an oxygenated atmosphere would not), contain precipitates of photocatalytic sulfide minerals that absorb harmful ultraviolet radiation, have wet-dry cycles that concentrate substrate solutions to concentrations amenable to spontaneous formation of biopolymers created both by chemical reactions in the hydrothermal environment, and by exposure to UV light during transport from vents to adjacent pools that would promote the formation of biomolecules. The hypothesized pre-biotic environments are similar to hydrothermal vents, with additional components that help explain peculiarities of the LUCA.
A phylogenomic and geochemical analysis of proteins plausibly traced to the LUCA shows that the ionic composition of its intracellular fluid is identical to that of hot springs. The LUCA likely was dependent upon synthesized organic matter for its growth. Experiments show that RNA-like polymers can be synthesized in wet-dry cycling and UV light exposure. These polymers were encapsulated in vesicles after condensation. Potential sources of organics at hot springs might have been transport by interplanetary dust particles, extraterrestrial projectiles, or atmospheric or geochemical synthesis. Hot springs could have been abundant in volcanic landmasses during the Hadean. | 0 | Theoretical and Fundamental Chemistry |
Penicillamine is a chiral drug with one chiral center and exists as a pair of enantiomers. (S)-penicillamine is the eutomer with the desired antiarthritic activity while the (R)-penicillamine is extremely toxic. | 0 | Theoretical and Fundamental Chemistry |
While the lead ISASMELT 5 t/h pilot plant was being designed in 1982–1983, MIM continued to use the 120 kg/h test rig to develop other processes, including the dross treatment process previously mentioned, and the treatment of lead-acid battery paste for lead recycling.
The MIM Holdings Board of Directors approved the construction of an ISASMELT plant at Britannia Refined Metals, the company's lead refinery at Northfleet in the United Kingdom, for commercial recovery of lead from battery paste to supplement the existing plant, which used a short rotary furnace to produce 10,000 t/y of lead. The new plant increased annual production to 30,000 t/y of recycled lead, and was commissioned in 1991. The ISASMELT furnace was used to produce low-antimony lead bullion from the battery paste and an antimony-rich slag that contained 55–65% lead oxide. While it was possible to recover the lead from the slag in the ISASMELT furnace by a reduction step, the total throughput of the plant was increased by treating the slag in the short rotary furnace when sufficient quantities of the slag had been generated. The plant was designed to treat 7.7 t/h of battery paste, but routinely treated 12 t/h. The plant was shut down in 2004 when Xstrata Zinc, which took over the MIM Holdings lead operations, decided to leave the lead recycling business.
A second lead ISASMELT plant for recovering lead from recycled batteries was commissioned in 2000 in Malaysia at Metal Reclamation Industries’ Pulau Indah plant. This ISASMELT plant has a design capacity of 40,000 t/y of lead bullion. | 1 | Applied and Interdisciplinary Chemistry |
NAIL-MS can be used to produce stable isotope labeled internal standards (ISTD). Therefore, cells are grown in medium which results in complete labeling of all nucleosides. The purified mix of nucleosides can then be used as ISTD which is needed for accurate absolute quantification of nucleosides by mass spectrometry. This mixture of labeled nucleosides is also referred to as SILIS (stable isotope labeled internal standard). The advantage of this approach is, that all modifications present in an organism can thereby be biosynthesized as labeled compounds. The production of SILIS was already done before the term NAIL-MS emerged. | 0 | Theoretical and Fundamental Chemistry |
In the Sun and other similar stars, those fusion reactions involve hydrogen ions. The high temperatures needed to sustain fusion reactions are maintained by a self-heating process in which energy from the fusion reaction heats the thermal plasma ions via particle collisions. A plasma enters what scientists call the burning plasma regime when the self-heating power exceeds any external heating.
The Sun is a burning plasma that has reached fusion ignition, meaning the Sun's plasma temperature is maintained solely by energy released from fusion. The Sun has been burning hydrogen for 4.5 billion years and is about halfway through its life cycle. | 0 | Theoretical and Fundamental Chemistry |
There are a number of types of mechanical screening equipment that cause segregation. These types are based on the motion of the machine through its motor drive.
*Circle-throw vibrating equipment - This type of equipment has an eccentric shaft that causes the frame of the shaker to lurch at a given angle. This lurching action literally throws the material forward and up. As the machine returns to its base state the material falls by gravity to physically lower level. This type of screening is used also in mining operations for large material with sizes that range from six inches to +20 mesh.
*High frequency vibrating equipment - This type of equipment drives the screen cloth only. Unlike above the frame of the equipment is fixed and only the screen vibrates. However, this equipment is similar to the above such that it still throws material off of it and allows the particles to cascade down the screen cloth. These screens are for sizes smaller than 1/8 of an inch to +150 mesh.
*Gyratory equipment - This type of equipment differs from the above two such that the machine gyrates in a circular motion at a near level plane at low angles. The drive is an eccentric gear box or eccentric weights.
*Trommel screens - Does not require vibration. Instead, material is fed into a horizontal rotating drum with screen panels around the diameter of the drum. | 1 | Applied and Interdisciplinary Chemistry |
Neutral red (toluylene red, Basic Red 5, or C.I. 50040) is a eurhodin dye used for staining in histology. It stains lysosomes red. It is used as a general stain in histology, as a counterstain in combination with other dyes, and for many staining methods. Together with Janus Green B, it is used to stain embryonal tissues and supravital staining of blood. Can be used for staining Golgi apparatus in cells and Nissl granules in neurons.
In microbiology, it is used in the MacConkey agar to differentiate bacteria for lactose fermentation.
[https://medium.com/@GSPChem/neutral-red-8d9c51584fa Neutral red] can be used as a vital stain. The Neutral Red Cytotoxicity Assay was first developed by Ellen Borenfreund in 1984. In the Neutral Red Assay live cells incorporate neutral red into their lysosomes. As cells begin to die, their ability to incorporate neutral red diminishes. Thus, loss of neutral red uptake corresponds to loss of cell viability. The neutral red is also used to stain cell cultures for plate titration of viruses.
Neutral red is added to some growth media for bacterial and cell cultures. It usually is available as a chloride salt.
Neutral red acts as a pH indicator, changing from red to yellow between pH 6.8 and 8.0. | 0 | Theoretical and Fundamental Chemistry |
In 2021 California banned PFASs for use in food packaging and from infant and children's products and also required PFAS cookware in the state to carry a warning label. | 0 | Theoretical and Fundamental Chemistry |
Unsaturated compounds, especially alkenes and alkynes, add halogens:
In oxychlorination, the combination of hydrogen chloride and oxygen serves as the equivalent of chlorine, as illustrated by this route to 1,2-dichloroethane:
The addition of halogens to alkenes proceeds via intermediate halonium ions. In special cases, such intermediates have been isolated.
Bromination is more selective than chlorination because the reaction is less exothermic. Illustrative of the bromination of an alkene is the route to the anesthetic halothane from trichloroethylene:
Iodination and bromination can be effected by the addition of iodine and bromine to alkenes. The reaction, which conveniently proceeds with the discharge of the color of , is the basis of the analytical method. The iodine number and bromine number are measures of the degree of unsaturation for fats and other organic compounds. | 0 | Theoretical and Fundamental Chemistry |
The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa. It uses air (or oxygen) and microorganisms to biologically oxidize organic pollutants, producing a waste sludge (or floc) containing the oxidized material.
The activated sludge process for removing carbonaceous pollution begins with an aeration tank where air (or oxygen) is injected into the waste water. This is followed by a settling tank to allow the biological flocs (the sludge blanket) to settle, thus separating the biological sludge from the clear treated water. Part of the waste sludge is recycled to the aeration tank and the remaining waste sludge is removed for further treatment and ultimate disposal.
Plant types include package plants, oxidation ditch, deep shaft/vertical treatment, surface-aerated basins, and sequencing batch reactors (SBRs). Aeration methods include diffused aeration, surface aerators (cones) or, rarely, pure oxygen aeration.
Sludge bulking can occur which makes activated sludge difficult to settle and frequently has an adverse impact on final effluent quality. Treating sludge bulking and managing the plant to avoid a recurrence requires skilled management and may require full-time staffing of a works to allow immediate intervention. A new development of the activated sludge process is the Nereda process which produces a granular sludge that settles very well. | 1 | Applied and Interdisciplinary Chemistry |
For , the system explodes since the exponential term dominates as time proceeds. We do not need to wait for a long time for to blow up. Because of the exponential forcing, at a finite value of . This time is interpreted as the ignition time or induction time of the system. When , the heat conduction term can be neglected in which case the problem admits an explicit solution,
At time , the system explodes. This time is also referred to as the adiabatic induction period since the heat conduction term is neglected.
In the near-critical condition, i.e., when , the system takes very long time to explode. The analysis for this limit was first carried out by Frank-Kamenetskii., although proper asymptotics were carried out only later by D. R. Kassoy and Amable Liñán including reactant consumption because reactant consumption is not negligible when . A simplified analysis without reactant consumption is presented here. Let us define a small parameter such that . For this case, the time evolution of is as follows: first it increases to steady-state temperature value corresponding to , which is given by at times of order , then it stays very close to this steady-state value for a long time before eventually exploding at a long time. The quantity of interest is the long-time estimate for the explosion. To find out the estimate, introduce the transformations and that is appropriate for the region where stays close to into the governing equation and collect only the leading-order terms to find out
where the boundary condition is derived by matching with the initial region wherein . The solution to the above-mentioned problem is given by
which immediately reveals that when Writing this condition in terms of , the explosion time in the near-critical condition is found to be
which implies that the ignition time as with a square-root singularity. | 1 | Applied and Interdisciplinary Chemistry |
Helical gear flowmeters get their name from the shape of their gears or rotors. These rotors resemble the shape of a helix, which is a spiral-shaped structure. As the fluid flows through the meter, it enters the compartments in the rotors, causing the rotors to rotate. The length of the rotor is sufficient that the inlet and outlet are always separated from each other thus blocking a free flow of liquid. The mating helical rotors create a progressive cavity which opens to admit fluid, seals itself off and then opens up to the downstream side to release the fluid. This happens in a continuous fashion and the flowrate is calculated from the speed of rotation. | 1 | Applied and Interdisciplinary Chemistry |
Anabolism is powered by catabolism, where large molecules are broken down into smaller parts and then used up in cellular respiration. Many anabolic processes are powered by the cleavage of adenosine triphosphate (ATP). Anabolism usually involves reduction and decreases entropy, making it unfavorable without energy input. The starting materials, called the precursor molecules, are joined using the chemical energy made available from hydrolyzing ATP, reducing the cofactors NAD, NADP, and FAD, or performing other favorable side reactions. Occasionally it can also be driven by entropy without energy input, in cases like the formation of the phospholipid bilayer of a cell, where hydrophobic interactions aggregate the molecules. | 1 | Applied and Interdisciplinary Chemistry |
Ovine forestomach matrix (OFM) (marketed as AROA ECM) is a layer of decellularized extracellular matrix (ECM) biomaterial isolated from the propria submucosa of the rumen of sheep. OFM is used in tissue engineering and as a tissue scaffold for wound healing and surgical applications | 1 | Applied and Interdisciplinary Chemistry |
FAS receptor gene is located on the long arm of chromosome 10 (10q24.1) in humans and on chromosome 19 in mice. The gene lies on the plus (Watson strand) and is 25,255 bases in length organized into nine protein encoding exons. Similar sequences related by evolution (orthologs) are found in most mammals. | 1 | Applied and Interdisciplinary Chemistry |
Firefly luciferase is thought to be a homolog of long-chain fatty acyl-CoA synthetase because of its ability to synthesize luciferyl-CoA from CoA and dehydroluciferyl-AMP. Inouye tested this hypothesis in 2010 by expressing the cDNA of Photinus pyralis and Lychocoriolaus lateralis luciferses in E. coli through cold shock gene expression. The resulting enzymes were then exposed to long-chain fatty acids, short-chain fatty acids, amino acids, and imino acids. Unsurprisingly, Inouye found that the luciferases only showed adenylation activity when exposed to long-chain fatty acids.
The gene product of CG6178 in Drosophila was also found to have high amino acid sequence similarity with firefly luciferase. While it did show high adenyltation activity when exposed to long-chain fatty acids, there was no luminescence when exposed to oxygen and LH-AMP– further suggesting that luciferase emerged as a long-chain fatty acyl-CoA homolog due to gene duplication. | 1 | Applied and Interdisciplinary Chemistry |
Although not a strictly living form of polymerization catalytic chain transfer polymerization must be mentioned as it figures significantly in the development of later forms of living free radical polymerization.
Discovered in the late 1970s in the USSR it was found that cobalt porphyrins were able to reduce the molecular weight during polymerization of methacrylates.
Later investigations showed that the cobalt glyoxime complexes were as effective as the porphyrin catalysts and also less oxygen sensitive. Due to their lower oxygen sensitivity these catalysts have been investigated much more thoroughly than the porphyrin catalysts.
The major products of catalytic chain transfer polymerization are vinyl-terminated polymer chains. One of the major drawbacks of the process is that catalytic chain transfer polymerization does not produce macromonomers but instead produces addition fragmentation agents. When a growing polymer chain reacts with the addition fragmentation agent the radical end-group attacks the vinyl bond and forms a bond. However, the resulting product is so hindered that the species undergoes fragmentation, leading eventually to telechelic species.
These addition fragmentation chain transfer agents do form graft copolymers with styrenic and acrylate species however they do so by first forming block copolymers and then incorporating these block copolymers into the main polymer backbone.
While high yields of macromonomers are possible with methacrylate monomers, low yields are obtained when using catalytic chain transfer agents during the polymerization of acrylate and stryenic monomers. This has been seen to be due to the interaction of the radical centre with the catalyst during these polymerization reactions.
The reversible reaction of the cobalt macrocycle with the growing radical is known as cobalt carbon bonding and in some cases leads to living polymerization reactions. | 0 | Theoretical and Fundamental Chemistry |
In the physical sciences, a phase is a region of material that is chemically uniform, physically distinct, and (often) mechanically separable. In a system consisting of ice and water in a glass jar, the ice cubes are one phase, the water is a second phase, and the humid air is a third phase over the ice and water. The glass of the jar is another separate phase. (See .)
More precisely, a phase is a region of space (a thermodynamic system), throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, magnetization and chemical composition.
The term phase is sometimes used as a synonym for state of matter, but there can be several immiscible phases of the same state of matter (as where oil and water separate into distinct phases, both in the liquid state). It is also sometimes used to refer to the equilibrium states shown on a phase diagram, described in terms of state variables such as pressure and temperature and demarcated by phase boundaries. (Phase boundaries relate to changes in the organization of matter, including for example a subtle change within the solid state from one crystal structure to another, as well as state-changes such as between solid and liquid.) These two usages are not commensurate with the formal definition given above and the intended meaning must be determined in part from the context in which the term is used. | 0 | Theoretical and Fundamental Chemistry |
In the early 1900s, immunologist Paul Ehrlich proposed the idea of a Zauberkugel – "magic bullet", conceived of as a compound which selectively targeted a disease-causing organism, and could deliver a toxin for that organism. This underpinned the concept of monoclonal antibodies and monoclonal drug conjugates. Ehrlich and Élie Metchnikoff received the 1908 Nobel Prize for Physiology or Medicine for providing the theoretical basis for immunology.
By the 1970s, lymphocytes producing a single antibody were known, in the form of multiple myeloma – a cancer affecting B-cells. These abnormal antibodies or paraproteins were used to study the structure of antibodies, but it was not yet possible to produce identical antibodies specific to a given antigen. In 1973, Jerrold Schwaber described the production of monoclonal antibodies using human–mouse hybrid cells. This work remains widely cited among those using human-derived hybridomas. In 1975, Georges Köhler and César Milstein succeeded in making fusions of myeloma cell lines with B cells to create hybridomas that could produce antibodies, specific to known antigens and that were immortalized. They and Niels Kaj Jerne shared the Nobel Prize in Physiology or Medicine in 1984 for the discovery.
In 1988, Gregory Winter and his team pioneered the techniques to humanize monoclonal antibodies, eliminating the reactions that many monoclonal antibodies caused in some patients. By the 1990s research was making progress in using monoclonal antibodies therapeutically, and in 2018, James P. Allison and Tasuku Honjo received the Nobel Prize in Physiology or Medicine for their discovery of cancer therapy by inhibition of negative immune regulation, using monoclonal antibodies that prevent inhibitory linkages.
The translational work needed to implement these ideas is credited to Lee Nadler. As explained in an NIH article, "He was the first to discover monoclonal antibodies directed against human B-cell–specific antigens and, in fact, all the known human B-cell–specific antigens were discovered in his laboratory. He is a true translational investigator, since he used these monoclonal antibodies to classify human B-cell leukemia and lymphomas as well as to create therapeutic agents for patients. . . More importantly, he was the first in the world to administer a monoclonal antibody to a human (a patient with B-cell lymphoma)." | 1 | Applied and Interdisciplinary Chemistry |
The BCA Micro BCA assay is a 3-component protocol which uses concentrated stocks of the Biuret reaction, BCA, and copper(II) reagents. It allows for an improved sensitivity of ~2 - 40 μg/mL vs 20 - 2000 µg/mL of the original BCA assay. However, it has a different, and generally speaking more sensitive, interference from non-protein components. Kits for the Micro BCA assay are available from at least two commercial vendors. Notably, the composition and use of a "Micro BCA Reagent and Protocol" was described in the original manuscript by Smith, and modern kits likely consist of an exact or highly similar formulation. The protocol consists of mixing Micro-Reagent B and the Copper Solution 25:1 to form Micro-Reagent C (MC), which is not shelf stable and should be freshly prepared, and then mixing MC 1:1 with Micro-Reagent A to produce the final (also unstable) assay working solution. Micro-Reagent A, Micro-Reagent B, and Copper Solution are stable indefinitely at room temperature.
Micro-Reagent A (MA)
* 8% w/v NaCO·HO (CAS: 5968-11-6)
* 1.6% w/v NaOH (CAS: 1310-73-2)
* 1.6% w/v Na tartrate (CAS: 868-18-8) (10x concentration as Reagent A in Original BCA Assay above)
* Sufficient NaHCO (CAS: 144-55-8) to adjust pH to 11.25
Micro-Reagent B (MB)
* 4% w/v BCA-Na (CAS: 979-88-4) (4x concentration as Reagent A in Original BCA Assay above)
Copper Solution
* 4% w/v CuSO·5HO (CAS: 7758-99-8) (Same concentration as Reagent B in Original BCA Assay above) | 1 | Applied and Interdisciplinary Chemistry |
In general acid catalysis all species capable of donating protons contribute to reaction rate acceleration. The strongest acids are most effective. Reactions in which proton transfer is rate-determining exhibit general acid catalysis, for example diazonium coupling reactions.
When keeping the pH at a constant level but changing the buffer concentration a change in rate signals a general acid catalysis. A constant rate is evidence for a specific acid catalyst. When reactions are conducted in nonpolar media, this kind of catalysis is important because the acid is often not ionized.
Enzymes catalyze reactions using general-acid and general-base catalysis. | 0 | Theoretical and Fundamental Chemistry |
Jābir ibn Ḥayyān (Arabic/Persian: , died c. 806−816), is the supposed author of an enormous number and variety of works in Arabic often called the Jabirian corpus. Popularly known as the father of chemistry, Jabir's works contain the oldest known systematic classification of chemical substances, and the oldest known instructions for deriving an inorganic compound (sal ammoniac or ammonium chloride) from organic substances (such as plants, blood, and hair) by chemical means. Some Arabic Jabirian works (e.g., the "Book of Mercy", and the "Book of Seventy") were later translated into Latin under the Latinized name "Geber". In 13th-century Europe an anonymous writer, usually referred to as pseudo-Geber, started to produce alchemical and metallurgical writings under this name. | 1 | Applied and Interdisciplinary Chemistry |
There is one assay office at Aradippou.
The Law governing the marking of precious metal articles has been ratified by the House of Representatives in 1991, creating a new semi-Governmental Organisation, the Cyprus Organisation for the Hallmarking of precious metals. The Cyprus Assay Office (CAO) is under the jurisdiction of the Ministry of Commerce, Industry and Tourism.
The Cyprus Hallmark consists of three compulsory symbols: 1. The manufacturers mark - Consists of the initials of the manufacturer of the article surrounded by a small shield; 2. The fineness mark - The purity of the metal, in parts per thousand; 3. The official mark - the Head of Aphrodite until December 2001 and a ship as from January 2002 denotes that the article is made of gold, and the fish that the article is made of silver. The manufacturers mark must be struck on the articles by the manufacturer before it is submitted to the Assay Office for hallmarking. The manufacturer may make arrangements for the manufacture's mark to be struck by the Assay Office upon submission of the article to be struck with the approved hallmarks.
The manufacturer's mark which is registered under the relevant section of the law shall include the initial letters of the name or names of the manufacturer and shall be of such design as may be approved by the Assay Office. The standards of fineness of gold and silver articles that are hallmarked are for gold: 375, 585, 750 and 916 parts per thousand; for silver: 800, 830 and 925 parts per thousand; no negative tolerance is permitted on the above standards of fineness. | 0 | Theoretical and Fundamental Chemistry |
In the episode "Encyclopedia Galactica" of his TV series Cosmos: A Personal Voyage, Carl Sagan speculates that some intelligent extraterrestrial beings might have a genetic code based on polyaromatic sulfonyl halides instead of DNA. | 0 | Theoretical and Fundamental Chemistry |
Thioesters hydrolyze to thiols and the carboxylic acid:
:RC(O)SR' + HO → RCOH + RSH
The carbonyl center in thioesters is more reactive toward amine than oxygen nucleophiles, giving amides:
This reaction is exploited in native chemical ligation, a protocol for peptide synthesis.
In a related reaction, thioesters can be converted into esters. Thioacetate esters can also be cleaved with methanethiol in the presence of stoichiometric base, as illustrated in the preparation of pent-4-yne-1-thiol:
A reaction unique to thioesters is the Fukuyama coupling, in which the thioester is coupled with an organozinc halide by a palladium catalyst to give a ketone. | 0 | Theoretical and Fundamental Chemistry |
The Lacassane Club was founded in 2013, as a subsidiary of The Lacassane Company, on 14,000 of the 21,000 acres owned by the company. The company offers personal and corporate hunting memberships that include access to the lodge, separate sleeping quarters called casitas and a 3 bedroom, 2 bath house called Jed's Cabin. The staff includes the club manager, a head guide, 4 other guides, an executive chef, and a Zoology/Wildlife Management biologist. | 1 | Applied and Interdisciplinary Chemistry |
All cells need energy to survive. Mitochondria is a double-membrane structure in the body cell that generates and transports essential metabolic products. The three layers of this structure are the outer membrane, intermembrane space, and inner membrane. The space inside the mitochondria is called the mitochondrial matrix, while the region outside is the cytosol. The outer membrane allows most small molecules to pass through. In contrast, the inner membrane transports specific molecules only, which is impermeable to many substances. Therefore, a shuttle is required for the transportation of molecules across the inner membrane. It acts as a pump to drive the substances from the inner membrane to the outside. | 1 | Applied and Interdisciplinary Chemistry |
Crown ethers, like cyclodextrin-type CSPs contain a chiral cavity. Crown ethers are immobilized on the silica surface to form chiral stationary phase. Crown ethers contain oxygen atoms within the cavity. The cyclic structure that contains apolar ethylene groups between oxygen forms hydrophobic inner cavity. Cram et al., introduced CSP based on chiral crown ethers and accomplished separation of amino acid. The crucial chiral recognition principle underlying crown ether-based enantiomer separation is based on the formation of numerous hydrogen bonds between the protonated primary amino group of the analyte and the ether oxygens of the crown structure. This structural requirement confines the application of crown ether-type CSPs to chiral compounds having primary amino groups adjoining the chiral centers, such as amino acids, amino acid derivatives. Progress in the field of crown ether-type CSPs have been reviewed. | 0 | Theoretical and Fundamental Chemistry |
Markovnikov is best known for Markovnikovs rule, elucidated in 1869 to describe addition reactions of H-X (where X' represents a halogen) to alkenes. According to this rule, the nucleophilic X- binds to the carbon (C) atom with fewer hydrogen atoms, while the proton binds to the carbon atom with more hydrogen atoms bonded to it. Thus, hydrogen chloride (HCl) reacts with propene, CH-CH=CH to produce 2-chloropropane CHCHClCH rather than the isomeric 1-chloropropane CHCHCHCl. The rule is useful in predicting the molecular structures of products of addition reactions. Why hydrogen bromide exhibited both Markovnikov as well as reversed-order, or anti-Markovnikov, addition, however, was not understood until Morris S. Kharasch offered an explanation in 1933. It is also called The Peroxide effect sometimes.
Hughes has discussed the reasons for Markovnikovs lack of recognition during his lifetime. Although he published mostly in Russian which was not understood by most Western European chemists, the 1870 article in which he first stated his rule was written in German. However the rule was included in a 4-page addendum to a 26-page article on isomeric butyric acids, and based on very slight experimental evidence even by the standards of the time. Hughes concludes that the rule was an inspired guess, unjustified by the evidence of the time, but which turned out later to be correct (in most cases). A more recent assessment, based on a reading of Markovnikovs Magistr Khimii and Doktor Khimii dissertations, contradicts this view, and points out that Markovnikov's Rule arises logically from his dissertations.
Markovnikov also contributed to organic chemistry by finding carbon rings with more than six carbon atoms, a ring with four carbon atoms in 1879, and a ring with seven in 1889.
Markovnikov also showed that butyric and isobutyric acids have the same chemical formula (CHO) but different structures; i.e., they are isomers. | 0 | Theoretical and Fundamental Chemistry |
Vapor phase osmometry is well suited for the analysis of oligomers and short polymers while higher polymers can be analyzed using other techniques such as membrane osmometry and light scattering. As of 2008, VPO faces competition from matrix-assisted laser desorption ionisation mass spectrometry (MALDI-MS), but VPO still has some advantages when fragmentation of samples for mass spectrometry may be problematic. | 0 | Theoretical and Fundamental Chemistry |
Microbial metabolism is the means by which a microbe obtains the energy and nutrients (e.g. carbon) it needs to live and reproduce. Microbes use many different types of metabolic strategies and species can often be differentiated from each other based on metabolic characteristics. The specific metabolic properties of a microbe are the major factors in determining that microbe's ecological niche, and often allow for that microbe to be useful in industrial processes or responsible for biogeochemical cycles. | 1 | Applied and Interdisciplinary Chemistry |
Secreted frizzled-related protein 1 (SFRP1) is a member of the SFRP family that contains a cysteine-rich domain homologous to the putative Wnt-binding site of Frizzled proteins. SFRPs act as soluble modulators of Wnt signaling. SFRP1 and SFRP5 may be involved in determining the polarity of photoreceptor cells in the retina. SFRP1 is expressed in several human tissues, with the highest levels in the heart.
The Secreted frizzled-related protein (SFRP) family consists of five secreted glycoproteins in humans (SFRP1, SFRP2, SFRP3, SFRP4, SFRP5) that act as extracellular signaling ligands. Each SFRP is ~300 amino acids in length and contains a cysteine-rich domain (CRD) that shares 30-50% sequence homology with the CRD of Frizzled (Fz) receptors. SFRPs are able to bind Wnt proteins and Fz receptors in the extracellular compartment. The interaction between SFRPs and Wnt proteins prevents the latter from binding the Fz receptors. SFRPs are also able to downregulate Wnt signaling by the formation of an inhibitory complex with the Frizzled receptors. The Wnt pathway plays a key role in embryonic development, cell differentiation and cell proliferation. It has been shown that the deregulation of this critical developmental pathway occurs in several human tumor entities.
SFRP1 is a 35 kDa prototypical member of the SFRP family. It acts as a biphasic modulator of Wnt signaling, counteracting Wnt-induced effects at high concentrations and promoting them at lower concentrations. It is located in a chromosomal region (8p12-p11.1) that is frequently deleted in breast cancer and is thought to harbour a tumor suppressor gene. | 1 | Applied and Interdisciplinary Chemistry |
Some metal carbonyls are prepared by the reduction of metal halides in the presence of high pressure of carbon monoxide. A variety of reducing agents are employed, including copper, aluminum, hydrogen, as well as metal alkyls such as triethylaluminium. Illustrative is the formation of chromium hexacarbonyl from anhydrous chromium(III) chloride in benzene with aluminum as a reducing agent, and aluminum chloride as the catalyst:
:CrCl + Al + 6 CO → Cr(CO) + AlCl
The use of metal alkyls, such as triethylaluminium and diethylzinc, as the reducing agent leads to the oxidative coupling of the alkyl radical to form the dimer alkane:
:WCl + 6 CO + 2 Al(CH) → W(CO) + 2 AlCl + 3 CH
Tungsten, molybdenum, manganese, and rhodium salts may be reduced with lithium aluminium hydride. Vanadium hexacarbonyl is prepared with sodium as a reducing agent in chelating solvents such as diglyme.
:VCl + 4 Na + 6 CO + 2 diglyme → Na(diglyme)[V(CO)] + 3 NaCl
:[V(CO)] + H → H[V(CO)] → H + V(CO)
In the aqueous phase, nickel or cobalt salts can be reduced, for example by sodium dithionite. In the presence of carbon monoxide, cobalt salts are quantitatively converted to the tetracarbonylcobalt(−1) anion:
:Co + + 6 OH + 4 CO → + 3 + 3 HO
Some metal carbonyls are prepared using CO directly as the reducing agent. In this way, Hieber and Fuchs first prepared dirhenium decacarbonyl from the oxide:
:ReO + 17 CO → Re(CO) + 7 CO
If metal oxides are used carbon dioxide is formed as a reaction product. In the reduction of metal chlorides with carbon monoxide phosgene is formed, as in the preparation of osmium carbonyl chloride from the chloride salts. Carbon monoxide is also suitable for the reduction of sulfides, where carbonyl sulfide is the byproduct. | 0 | Theoretical and Fundamental Chemistry |
A wide range of Fe(III)-bearing minerals have been observed to function as terminal electron acceptors, including magnetite, hematite, goethite, lepidocrocite, ferrihydrite, hydrous ferric oxide, smectite, illite, jarosite, among others. | 1 | Applied and Interdisciplinary Chemistry |
Consistently producing ligand-targeted liposomes through traditional methods is difficult. The process can be tedious, challenging to control and result in a poorly defined system. Using the ‘post-insertion’ technique that involves micelles formed from PEG-linked ligands incubated with pre-formed, drug-loaded, non-targeted liposomes and they combine to form LTLs can limit the associated manufacturing challenges.
When using certain ligands, such as antibodies, the risk for an immunological reaction poses a risk. Liposome design including size, charge, morphology, composition, surface characteristics, and dose size can all influence the immune response to administered LTLs. The ligands used can elicit an immune response when introduced into the body. For example, when peptide ligands such as CDX are used for brain-targeted delivery systems, they are immunogenic and trigger an immune response. Complement Activation-Related Pseudo-allergies (CARPA) is a hypersensitivity syndrome that can be triggered when LTLs activate the innate immune system and the complement system. CARPA can cause many side effects including anaphylaxis, cardiopulmonary distress, and facial swelling. These side effects have the potential to be severe, which generates concern when administering LTLs to patients with health problems, especially cardiovascular issues. This reaction can be reduced by slowing infusion rates or incorporating the use of allergy medicines like antihistamines into the treatment regimen.
Due to the immune response, LTLs can experience the accelerated blood clearance (ABC) phenomenon. This phenomenon is more common in repeated dosage usage of LTLs, such as multi-dose PEGylated formulas, because of immunological memory. The pharmokinetics and clearance rates of the second dose have been shown to be significantly reduced while accumulation in the spleen and liver increases. This poses challenges for clinical applications of LTLs that require multiple doses to be effective.
Ligand-targeted liposomes need specific conditions to remain intact for use. Controlling environmental factors such as temperature and pH is necessary to maintain the integrity of the molecules. This can be helpful for temperature-sensitive or pH-dependent drug release conditions but is harmful if the pH changes at an inopportune time. This technology can also be used in combination with enzymes such as in Gal-Dox, which releases active doxorubicin in combination with β-Galactosidase. Making sure the compound does not encounter the enzyme too early is also important for effective usage.
There is a possibility that LTLs lead to immunosuppression. LTLs are cleared through the RES which is part of the innate immune system. Macrophage saturation to remove the liposomes could impact the ability of the phagocytic cells to function properly to conduct immune functions. Significant immune suppression has not been observed in clinical cases for therapeutic doses of LTLs containing non-cytotoxic drugs. | 1 | Applied and Interdisciplinary Chemistry |
Svetozar Lj. Jovanović (1895–1951) was a Serbian chemist and assistant professor of chemistry from 1925 to 1941. He specialized in the field of analytical chemistry.
Jovanović developed a new electroanalytical method for the quantitative determination of antimony
and a method for the separation of copper from zinc by rapid electrolysis. He studied the gravrimetric determination of problems, such as the manufacture of drugs and, in particular, the practical utilization of the countrys paraffin shales. He co-authored with Momir Jovanović a book on Principles of Qualitative Chemical Analysis (Serbian: Kvalitativna hemijska aanaliza). He also wrote an article for a Serbian medical journal titled "Diagnostic evaluation of Vidals reaction". | 0 | Theoretical and Fundamental Chemistry |
Fermentation is the main source of ethanol in the production of ethanol fuel. Common crops such as sugar cane, potato, cassava, and maize are fermented by yeast to produce ethanol which is further processed to become fuel. | 1 | Applied and Interdisciplinary Chemistry |
One of the most famous reversible photochromic applications is color changing lenses for sunglasses. The largest limitation in using photochromic technology is that the materials cannot be made stable enough to withstand thousands of hours of outdoor exposure so long-term outdoor applications are not appropriate at this time.
The switching speed of photochromic dyes is highly sensitive to the rigidity of the environment around the dye. As a result, they switch most rapidly in solution and slowest in the rigid environment like a polymer lens. In 2005 it was reported that attaching flexible polymers with low glass transition temperature (for example siloxanes or polybutyl acrylate) to the dyes allows them to switch much more rapidly in a rigid lens. Some spirooxazines with siloxane polymers attached switch at near solution-like speeds even though they are in a rigid lens matrix. | 0 | Theoretical and Fundamental Chemistry |
Automated peptide synthesis involves the condensation of the amino group of protected amino acids with the activated ester. HOBt is used to produce such activated esters. These esters are insoluble (like the N-hydroxysuccinimide esters) and react with amines at ambient temperature to give amides.
HOBt is also used for the synthesis of amides from carboxylic acids aside from amino acids. These substrates may not be convertible to the acyl chlorides. For instance amide derivatives of ionophoric antibiotics have been prepared in this way. | 1 | Applied and Interdisciplinary Chemistry |
The water–gas shift reaction (WGSR) describes the reaction of carbon monoxide and water vapor to form carbon dioxide and hydrogen:
: CO + HO CO + H
The water gas shift reaction was discovered by Italian physicist Felice Fontana in 1780. It was not until much later that the industrial value of this reaction was realized. Before the early 20th century, hydrogen was obtained by reacting steam under high pressure with iron to produce iron oxide and hydrogen. With the development of industrial processes that required hydrogen, such as the Haber–Bosch ammonia synthesis, a less expensive and more efficient method of hydrogen production was needed. As a resolution to this problem, the WGSR was combined with the gasification of coal to produce hydrogen. | 0 | Theoretical and Fundamental Chemistry |
Either the enantiomer of the substrate is derivatized with two enantiomers of the CDA or both enantiomers of the substrate are derivatized with one enantiomer of the CDA. Two diastereomers form in both cases and the chemical shifts of their nuclei are evaluated to assign the configuration of the substrate. | 0 | Theoretical and Fundamental Chemistry |
Transcription activator-like effector nucleases (TALENs) also contain a DNA binding domain and a nuclease that can cleave DNA. The DNA binding region consists of amino acid repeats that each recognize a single base pair of the desired targeted DNA sequence. If this cleavage is targeted to a gene coding region, and NHEJ-mediated repair introduces insertions and deletions, a frameshift mutation often results, thus disrupting function of the gene. | 1 | Applied and Interdisciplinary Chemistry |
So far only about two dozen sites have been identified where iron was made before the Roman invasion, mostly scattered across East Sussex and the Vale of Kent. A large site at Broadfield, Crawley is the westernmost place where smelting has been ascertained, although there is a possible site associated with an Iron Age enclosure at Piper's Copse near Northchapel in the western Weald. Continuity of pottery styles from the Iron Age into the early Roman period makes precise dating of many sites to before or after the Roman conquest difficult. Carbon dating has identified a site at Cullinghurst Wood, Hartfield to between 350 and 750 BC.
During his invasions of Britain in 55 and 54 BC Julius Caesar noted iron production near the coast, possibly at known sites at Sedlescombe and Crowhurst Park near Hastings. | 1 | Applied and Interdisciplinary Chemistry |
On 6 March 1943, Eva and her parents were transported to the Theresienstadt Ghetto in Terezín, where her father was separated from her and her mother. In Terezín, she worked in agriculture, so she was able to go into the ghetto and managed to make contact with her father. In December 1943, she and her mother were transferred to Auschwitz concentration camp, where she stayed until June 1944. After six months of horrible conditions at Auschwitz, Eva and her mother were unexpectedly recognized as able to work and were relocated to the Dessauer Ufer camp of the Neuengamme concentration camp in Hamburg, where she experienced better conditions. Her final transport was without her mother to Bergen-Belsen concentration camp in April 1945, which was liberated the same month. | 0 | Theoretical and Fundamental Chemistry |
Aerobic organisms use a process called aerobic respiration to create ATP from ADP and a phosphate. Glucose (a monosaccharide) is oxidized to power the electron transport chain:
This equation is a summary of what happens in three series of biochemical reactions: glycolysis, the Krebs cycle (also known as the Citric acid cycle), and oxidative phosphorylation.
:CHO + 6 O + 38 ADP + 38 phosphate → 6 CO + 44 HO + 38 ATP
In Oxidative phosphorylation, ATP is synthesized from ADP and a phosphate using ATP synthase. ATP synthase is powered by a proton-motive force created by using the energy generated from the electron transport chain. A hydrogen ion (H) has a positive charge and if separated by a cellular membrane, it creates a difference in charge between the inside and outside of the membrane. Oxidative phosphorylation occurs in the mitochondria of eukaryotes.
Aerobic respiration needs O because it acts as the terminal electron acceptor in prokaryotes' electron transport chain. Molecular Oxygen is reduced to water in this process. | 1 | Applied and Interdisciplinary Chemistry |
Serotonylation is a receptor independent signaling mechanism by which serotonin activates intracellular processes by creating long lasting covalent bonds upon proteins. It occurs through the modification of proteins by the attachment of serotonin on their glutamine residues. This happens through the enzyme transglutaminase and the creation of glutamyl-amide bonds. This process occurs following serotonin transportation into the cell rather on plasma membranes as with the brief interactions that serotonin has when it activates 5-HT receptors. | 1 | Applied and Interdisciplinary Chemistry |
In theoretical physics, the electroweak model breaks parity maximally. All its fermions are chiral Weyl fermions, which means that the charged weak gauge bosons W and W only couple to left-handed quarks and leptons.
Some theorists found this objectionable, and so conjectured a GUT extension of the weak force which has new, high energy W′ and Z′ bosons, which do couple with right handed quarks and leptons:
to
Here, (pronounced " left") is from above, while is the baryon number minus the lepton number. The electric charge formula in this model is given by
where and are the left and right weak isospin values of the fields in the theory.
There is also the chromodynamic . The idea was to restore parity by introducing a left-right symmetry. This is a group extension of (the left-right symmetry) by
to the semidirect product
This has two connected components where acts as an automorphism, which is the composition of an involutive outer automorphism of with the interchange of the left and right copies of with the reversal of . It was shown by Mohapatra & Senjanovic (1975) that left-right symmetry can be spontaneously broken to give a chiral low energy theory, which is the Standard Model of Glashow, Weinberg, and Salam, and also connects the small observed neutrino masses to the breaking of left-right symmetry via the seesaw mechanism.
In this setting, the chiral quarks
and
are unified into an irreducible representation ("irrep")
The leptons are also unified into an irreducible representation
The Higgs bosons needed to implement the breaking of left-right symmetry down to the Standard Model are
This then provides three sterile neutrinos which are perfectly consistent with neutrino oscillation data. Within the seesaw mechanism, the sterile neutrinos become superheavy without affecting physics at low energies.
Because the left–right symmetry is spontaneously broken, left–right models predict domain walls. This left-right symmetry idea first appeared in the Pati–Salam model (1974) and Mohapatra–Pati models (1975). | 0 | Theoretical and Fundamental Chemistry |
The van t Hoff factor (named after Dutch chemist Jacobus Henricus van t Hoff) is a measure of the effect of a solute on colligative properties such as osmotic pressure, relative lowering in vapor pressure, boiling-point elevation and freezing-point depression. The van t Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass. For most non-electrolytes dissolved in water, the van t Hoff factor is essentially 1.
For most ionic compounds dissolved in water, the van t Hoff factor is equal to the number of discrete ions in a formula unit of the substance. This is true for ideal solutions only, as occasionally ion pairing occurs in solution. At a given instant a small percentage of the ions are paired and count as a single particle. Ion pairing occurs to some extent in all electrolyte solutions. This causes the measured van t Hoff factor to be less than that predicted in an ideal solution. The deviation for the van 't Hoff factor tends to be greatest where the ions have multiple charges.
The factor binds osmolarity to molarity and osmolality to molality. | 0 | Theoretical and Fundamental Chemistry |
For basic science, notably developmental biology and cell biology, PSC-derived cells allow to study at the molecular and cellular levels fundamental questions in vitro, that would have been otherwise extremely difficult or impossible to study for technical and ethical reasons in vivo such as embryonic development of human. In particular, differentiating cells are amenable for quantitative and qualitative studies.
More complex processes can also be studied in vitro and formation of organoids, including cerebroids, optic cup and kidney have been described. | 1 | Applied and Interdisciplinary Chemistry |
An anodized oxide layer has a thickness in the range of to several micrometers. Standards for titanium anodizing are given by AMS 2487 and AMS 2488.
AMS 2488 Type III anodizing of titanium generates an array of different colours without dyes, for which it is sometimes used in art, costume jewellery, body piercing jewellery and wedding rings. The colour formed is dependent on the thickness of the oxide (which is determined by the anodizing voltage); it is caused by the interference of light reflecting off the oxide surface with light travelling through it and reflecting off the underlying metal surface. AMS 2488 Type II anodizing produces a thicker matte grey finish with higher wear resistance. | 1 | Applied and Interdisciplinary Chemistry |
The Raman shift chemical imaging spectral range spans from approximately 50 to 4,000 cm; the actual spectral range over which a particular Raman measurement is made is a function of the laser excitation frequency. The basic principle behind Raman spectroscopy differs from the MIR and NIR in that the x-axis of the Raman spectrum is measured as a function of energy shift (in cm) relative to the frequency of the laser used as the source of radiation. Briefly, the Raman spectrum arises from inelastic scattering of incident photons, which requires a change in polarizability with vibration, as opposed to infrared absorption, which requires a change in dipole moment with vibration. The end result is spectral information that is similar and in many cases complementary to the MIR. The Raman effect is weak - only about one in 10 photons incident to the sample undergoes Raman scattering. Both organic and inorganic materials possess a Raman spectrum; they generally produce sharp bands that are chemically specific. Fluorescence is a competing phenomenon and, depending on the sample, can overwhelm the Raman signal, for both bulk spectroscopy and imaging implementations.
Raman chemical imaging requires little or no sample preparation. However, physical sample sectioning may be used to expose the surface of interest, with care taken to obtain a surface that is as flat as possible. The conditions required for a particular measurement dictate the level of invasiveness of the technique, and samples that are sensitive to high power laser radiation may be damaged during analysis. It is relatively insensitive to the presence of water in the sample and is therefore useful for imaging samples that contain water such as biological material. | 0 | Theoretical and Fundamental Chemistry |
* Termination: The TE-domain (thio-esterase domain) hydrolyzes the completed polypeptide chain from the PCP-domain of the previous module, thereby often forming cyclic amides (lactams) or cyclic esters (lactones).
* Also, the peptide can be released by an R-domain that reduces the thioester bond to terminal aldehyde or alcohol. | 1 | Applied and Interdisciplinary Chemistry |
There are three groups of methods for correlating and predicting LCSTs. The first group proposes models that are based on a solid theoretical background using liquid–liquid or vapor–liquid experimental data. These methods require experimental data to adjust the unknown parameters, resulting in limited predictive ability . Another approach uses empirical equations that correlate θ (LCST) with physicochemical properties such as density, critical properties etc., but suffers from the disadvantage that these properties are not always available. A new approach proposed by Liu and Zhong develops linear models for the prediction of θ(LCST) using molecular connectivity indices, which depends only on the solvent and polymer structures. The latter approach has proven to be a very useful technique in quantitative structure–activity/property relationships (QSAR/QSPR) research for polymers and polymer solutions. QSAR/QSPR studies constitute an attempt to reduce the trial-and-error element in the design of compounds with desired activity/properties by establishing mathematical relationships between the activity/property of interest and measurable or computable parameters, such as topological, physicochemical, stereochemistry, or electronic indices. More recently QSPR models for the prediction of the θ (LCST) using molecular (electronic, physicochemical etc.) descriptors have been published. Using validated robust QSPR models, experimental time and effort can be reduced significantly as reliable estimates of θ (LCST) for polymer solutions can be obtained before they are actually synthesized in the laboratory. | 0 | Theoretical and Fundamental Chemistry |
The oral bioavailability of drospirenone is between 66 and 85%. Peak levels occur 1 to 6 hours after an oral dose. Levels are about 27 ng/mL after a single 4 mg dose. There is 1.5- to 2-fold accumulation in drospirenone levels with continuous administration, with steady-state levels of drospirenone achieved after 7 to 10 days of administration. Peak levels of drospirenone at steady state with 4 mg/day drospirenone are about 41 ng/mL. With the combination of 30 μg/day ethinylestradiol and 3 mg/day drospirenone, peak levels of drospirenone after a single dose are 35 ng/mL, and levels at steady state are 60 to 87 ng/mL at peak and 20 to 25 ng/mL at trough. The pharmacokinetics of oral drospirenone are linear with a single dose across a dose range of 1 to 10 mg. Intake of drospirenone with food does not influence the absorption of drospirenone. | 0 | Theoretical and Fundamental Chemistry |
This journal is abstracted and indexed in BIOSIS, Chemical Abstracts, Clinical Chemistry Lookout, Current Clinical Chemistry, Current Contents/Life Sciences, EMBASE, EMBiology, FRANCIS, Index Chemica, Informedicus, MEDLINE, PASCAL, Reference Update, and Scopus. | 1 | Applied and Interdisciplinary Chemistry |
SFP for a given fan system and operating point (combination of flow rate and pressure rise) is defined as:
where:
* is the electrical power used by the fan (or sum of all fans in the ventilation system) [kW]
* is the gross amount of air circulated through the fan (or ventilation system) [m/s]
There are various sub-definitions of SFP for different specific applications, including SFP (building energy performance calculations), SFP (for performance verification tests), SFP (individual fan), SFP (air handling unit), SFP (fan coil unit), and SFP (whole building). These are explained in and in part in. Reference 1 also describes how account for intermittently operated fans, e.g. kitchen hoods, and part-load performance in variable air volume (VAV) systems.
SFP can be expressed in the following equivalent SI units: | 1 | Applied and Interdisciplinary Chemistry |
The development of orthogonal protecting groups is a problem in organic synthesis because these protecting groups allow each instance of a common functional group, such as the hydroxyl group, to be distinguished during the synthesis of a complex molecule. A very common protecting group for the hydroxyl functional group is the para-methoxy benzyl (PMB) ether. This protecting group is chemically similar to the less electron-rich benzyl ether. Typically, selective cleavage of a PMB ether in the presence of a benzyl ether uses strong stoichiometric oxidants such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or ceric ammonium nitrate (CAN). PMB ethers are far more susceptible to oxidation than benzyl ethers since they are more electron-rich. The selective deprotection of PMB ethers can be achieved through the use of bis-(2-(2,4-difluorophenyl)-5-trifluoromethylpyridine)-(4,4'-ditertbutylbipyridine)iridium(III) hexafluorophosphate (Ir[dF(CF)ppy](dtbbpy)PF) and a mild stoichiometric oxidant such as bromotrichloromethane, BrCCl. The photoexcited iridium catalyst is reducing enough to fragment the bromotrichloromethane to form a trichloromethyl radical, bromide anion, and the Ir(IV) complex. The electron-poor fluorinated ligands makes the iridium complex oxidising enough to accept an electron from an electron-rich arene such as a PMB ether. After the arene is oxidized, it will readily participate in hydrogen atom transfer with trichloromethyl radical to form chloroform and an oxocarbenium ion, which is readily hydrolyzed to reveal the free hydroxide. This reaction was demonstrated to be orthogonal to many common protecting groups when a base was added to neutralise the HBr produced. | 0 | Theoretical and Fundamental Chemistry |
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