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Intracellular pathogens often reside in immune cells like macrophages. These pathogens can be obligate or facultative intracellular pathogens. Changing the innate immune response of these host-cells can alter the pathogens ability to live inside the cell. Many of these immunomodulatory host-directed therapies are adjuvants or pathogen-associated molecular patterns. They can include Toll-like receptors (TLRs), NOD-like receptors (NLRs), C-type lectin receptors (CLRs), mannose receptor (MR), dendritic cell-specific intracellular adhesion molecule 3 (ICAM3)-grabbing nonintegrin (DC-SIGN), complement receptors, Fc receptors, and DNA sensors (e.g., STING). Epithelial cells also host pathogens, like Salmonella enterica'. These immunomodulatory agents can also alter the epithelial cell environments, since they also have a role in innate signalling. | 1 | Applied and Interdisciplinary Chemistry |
An urban stream is a formerly natural waterway that flows through a heavily populated area. Often times, urban streams are low-lying points in the landscape that characterize catchment urbanization. Urban streams are often polluted by urban runoff and combined sewer outflows. Water scarcity makes flow management in the rehabilitation of urban streams problematic. | 1 | Applied and Interdisciplinary Chemistry |
The declassification of the program was a large topic of discussion between scientists at all of the laboratories involved with the project and at the Sherwood conferences. The reasoning for an initial high classification status was that if the research into controlled fusion were to be successful then it would be a significant advantage in regards to military aspects. In particular, fusion products high-energy neutrons which could be used to enrich uranium into plutonium for nuclear bomb production. If a small fusion machine was possible, this represented a significant proliferation risk.
However, as the difficultly in making a working fusion reactor became increasingly clear, fears of hidden reactors faded. Additionally, while some of the required industrial work could be conducted without access to the classified information, there were some instances where the classified information of the program was a necessity for those people working on projects such as the large-scale stellarator, the ultra-high vacuum, and the problem of energy storage. In these instances, there was a contract with the Commission that the information that was being used would only be shared with the personnel that was directly working on the project. It soon became apparent that industrial companies were expected to become highly invested in the area of fission and because of this it became clear that these companies should have full access to the research information obtained by Project Sherwood. In June 1956, permits for the research information from Project Sherwood became available through the Commission for companies that were qualified.
Between 1955 and 1958, information became more and more available to the public with its gradual declassification beginning with the sharing of information with the United Kingdom. Huge supporters of declassification of the program included the director of the Division of Research, Thomas Johnson, and a member of his staff, Amasa Bishop. Some of their reasoning for wanting declassification was that the secrecy of the project could negatively impact their ability to enlist and employ experienced personnel to the program. The also argued that it would change the way their conferences could be held. The scientists working on the project would be able to freely discuss their findings with others in the scientific community rather than only the scientists working on the same project.
In 1956, Soviet physicist Igor Kurchatov gave a talk in the UK where he revealed the entire Soviet fusion program and detailed the problems they were having. Now that the very group of people the classification was intended to keep in the dark were at roughly the same stage of development, there was no obvious reason to continue classification. While the UK had been among the first to classify their program in the aftermath of the Klaus Fuchs affair in 1950, in the summer of 1957 they appeared to have successfully created fusion in their new ZETA and were clamoring to tell the press of their advances. Their agreement to share information with the US required them to classify their work, and now they also began pressing the US to agree to declassification.
By May 1958, basic information about the various projects within Project Sherwood including the stellarator, magnetic mirrors, and molecular ion beams had been released to the public. | 0 | Theoretical and Fundamental Chemistry |
A negative balance is a result of energy intake being less than what is consumed in external work and other bodily means of energy expenditure.
The main cause is undereating due to a medical condition such as decreased appetite, anorexia nervosa, digestive disease, or due to some circumstance such as fasting or lack of access to food. Hyperthyroidism can also be a cause. | 1 | Applied and Interdisciplinary Chemistry |
Newer luciferases have recently been identified that, unlike other luciferases, are naturally secreted molecules. One such example is the Metridia coelenterazine-dependent luciferase (MetLuc, ) that is derived from the marine copepod Metridia longa. The Metridia longa secreted luciferase gene encodes a 24 kDa protein containing an N-terminal secretory signal peptide of 17 amino acid residues. The sensitivity and high signal intensity of this luciferase molecule proves advantageous in many reporter studies. Some of the benefits of using a secreted reporter molecule like MetLuc is its no-lysis protocol that allows one to be able to conduct live cell assays and multiple assays on the same cell. | 1 | Applied and Interdisciplinary Chemistry |
Hydrothermal H may have played a major role in pre-biotic chemistry. Production of H by serpentinization supported formation of the reactants proposed in the iron-sulfur world origin of life hypothesis. The subsequent evolution of hydrogenotrophic methanogenesis is hypothesized as one of the earliest metabolisms on Earth.
Serpentinization can occur on any planetary body with chondritic composition. The discovery of H on other ocean worlds, such as Enceladus, suggests that similar processes are ongoing elsewhere in the Solar System, and potentially in other planetary systems as well. | 1 | Applied and Interdisciplinary Chemistry |
isomiRs (from iso- + miR) are miRNA sequences that have variations with respect to the reference sequence. The term was coined by Morin et al in 2008. It has been found that isomiR expression profiles can also exhibit race, population, and gender dependencies.
There are four main variation types:
*5 trimming—the 5 dicing site is upstream or downstream from the reference miRNA sequence
*3 trimming—the 3 dicing site is upstream or downstream from the reference miRNA sequence
*3 nucleotide addition—nucleotides added to the 3 end of the reference miRNA
*nucleotide substitution—nucleotides changes from the miRNA precursor. It is thought that may be similar process than post-transcriptional modifications. | 1 | Applied and Interdisciplinary Chemistry |
2,3-butanediol fermentation produces smaller amounts of acid than mixed acid fermentation, and butanediol, ethanol, CO and H are the end products. While equal amounts of CO and H are created during mixed acid fermentation, butanediol fermentation produces more than twice the amount of CO because the gases are not produced only by formate hydrogen lyase as they are in mixed acid fermentation.
2,3 Butanediol is produced at varying levels in aerated fermentations as long as the dissolved oxygen level is limiting (i.e., the culture is trying to consume more oxygen than is available). The degree of oxygen limitation dictates the ratios of 2,3-butanediol to by-products produced. | 1 | Applied and Interdisciplinary Chemistry |
These probes are mostly used to monitor corrosion caused by erosion or wear. Generally, the erosion are occurred in gas pipelines where the speed of fluid cause erosion. Here the erosion is more important than corrosion. | 1 | Applied and Interdisciplinary Chemistry |
Organic acids have the ability to dissolve soil minerals, and can destroy silicate minerals and iron and aluminum oxides, so that metal ions are precipitated and complexed with organic complexing agents through ion exchange, surface absorption, and chelation-reaction mechanisms. For example, at low pH, a large number of metal ions are complexed with organic acids. When the organic acid occupies the coordination position of the metal ion, it can prevent the precipitation and crystallization of the metal oxide and increase its solubility. Conversely, at high pH (e.g. 7–8), dissolved metal ions, such as Fe(III), will precipitate out of the solution as insoluble complexes. | 0 | Theoretical and Fundamental Chemistry |
During heavy rainy seasons some areas can experience heavy floods while other areas might be experiencing drought like situations. With network of rivers this problem can be greatly avoided by channeling excess water to areas that are not experiencing a flood or are dry. | 1 | Applied and Interdisciplinary Chemistry |
HeSE has been used to study the diffusion rates and mechanisms of atoms and molecules (adsorbates) at surfaces. A non-exhaustive list of the research themes associated with HeSE diffusion measurements include:
nuclear quantum effects in the surface diffusion of atomic hydrogen;
benchmarking the adsorbate/surface free energy landscape;
energy exchange (friction) between adsorbates and the surface; pairwise and many-body inter-adsorbate interactions. | 0 | Theoretical and Fundamental Chemistry |
The previous conductance equations, written in terms of extensive properties, can be reformulated in terms of intensive properties. , and conductance, .
From the electrical formula: , where ρ is resistivity, x is length, and A is cross-sectional area, we have , where G is conductance, k is conductivity, x is length, and A is cross-sectional area.
For heat,
where is the conductance.
Fourier's law can also be stated as:
analogous to Ohm's law, or
The reciprocal of conductance is resistance, R, given by:
analogous to Ohm's law,
The rules for combining resistances and conductances (in series and parallel) are the same for both heat flow and electric current. | 1 | Applied and Interdisciplinary Chemistry |
Tartaric acid may be most immediately recognizable to wine drinkers as the source of "wine diamonds", the small potassium bitartrate crystals that sometimes form spontaneously on the cork or bottom of the bottle. These "tartrates" are harmless, despite sometimes being mistaken for broken glass, and are prevented in many wines through cold stabilization (which is not always preferred since it can change the wine's profile). The tartrates remaining on the inside of aging barrels were at one time a major industrial source of potassium bitartrate.
Tartaric acid plays an important role chemically, lowering the pH of fermenting "must" to a level where many undesirable spoilage bacteria cannot live, and acting as a preservative after fermentation. In the mouth, tartaric acid provides some of the tartness in the wine, although citric and malic acids also play a role. | 0 | Theoretical and Fundamental Chemistry |
Photolysis or thermolysis of mononuclear carbonyls generates di- and polymetallic carbonyls such as diiron nonacarbonyl (Fe(CO)). On further heating, the products decompose eventually into the metal and carbon monoxide.
:2 Fe(CO) → Fe(CO) + CO
The thermal decomposition of triosmium dodecacarbonyl (Os(CO)) provides higher-nuclear osmium carbonyl clusters such as Os(CO), Os(CO) up to Os(CO).
Mixed ligand carbonyls of ruthenium, osmium, rhodium, and iridium are often generated by abstraction of CO from solvents such as dimethylformamide (DMF) and 2-methoxyethanol. Typical is the synthesis of IrCl(CO)(PPh) from the reaction of iridium(III) chloride and triphenylphosphine in boiling DMF solution. | 0 | Theoretical and Fundamental Chemistry |
ANCAs are associated with small vessel vasculitides including granulomatosis with polyangiitis, microscopic polyangiitis, primary pauci-immune necrotizing crescentic glomerulonephritis (a type of renal-limited microscopic polyangiitis), eosinophilic granulomatosis with polyangiitis and drug induced vasculitides. ANCA-associated vasculitides (AAV) have new classification criteria, updated in 2022.
PR3 directed c-ANCA is present in 80-90% of granulomatosis with polyangiitis, 20-40% of microscopic polyangiitis, 20-40% of pauci-immune crescentic glomerulonephritis and 35% of eosinophilic granulomatosis with polyangiitis. c-ANCA (atypical) is present in 80% of cystic fibrosis (with BPI as the target antigen) and also in inflammatory bowel disease, primary sclerosing cholangitis and rheumatoid arthritis (with antibodies to multiple antigenic targets). p-ANCA with MPO specificity is found in 50% of microscopic polyangiitis, 50% of primary pauci-immune necrotizing crescentic glomerulonephritis and 35% of eosinophilic granulomatosis with polyangiitis. p-ANCA with specificity to other antigens are associated with inflammatory bowel disease, rheumatoid arthritis, drug-induced vasculitis, autoimmune liver disease, drug induced syndromes and parasitic infections. Atypical ANCA is associated with drug-induced systemic vasculitis, inflammatory bowel disease and rheumatoid arthritis. The ANCA‐positive rate is much higher in patients with type 1 diabetes mellitus than in healthy individuals.
Levamisole, which is a common adulterant of cocaine, can cause an ANCA positive vasculitis.
The presence or absence of ANCA cannot indicate presence or absence of disease and results are correlated with clinical features. The association of ANCA and disease activity remains controversial; however, the reappearance of ANCA after treatment can indicate a relapse. | 1 | Applied and Interdisciplinary Chemistry |
The allowed electron energies in the topological insulator were probed with the well-employed angle-resolved photoemission spectroscopy (ARPES). Γ and M space points were found to exhibit binding energies of 0.3 eV and 0.8 eV, respectively. ARPES also probed the Fermi electron velocities along the x and y axes to be 0.1(1)×106 m*s and 0.60(4)×106 m*s. The emerging non-trivial states of the topological insulator are expected to show at the space point where the conductive and valence bands almost cross or, in other words, display the smallest band gap. This point indeed showed a binding energy of 0.06 eV as measured by ARPES. ARPES measurements on a different β-BiBr topological insulator phase show similarity to its iodine counterpart. | 0 | Theoretical and Fundamental Chemistry |
Following phenotypic selection, genomic DNA is extracted from the selected clones, alongside a control cell population. In the most common protocols for genome-wide knockouts, a Next-generation sequencing (NGS) library is created by a two step polymerase chain reaction (PCR). The first step amplifies the sgRNA region, using primers specific to the lentiviral integration sequence, and the second step adds Illumina i5 and i7 sequences. NGS of the PCR products allows the recovered sgRNAs to be identified, and a quantification step can be used to determine the relative abundance of each sgRNA.
The final step in the screen is to computationally evaluate the significantly enriched or depleted sgRNAs, trace them back to their corresponding genes, and in turn determine which genes and pathways could be responsible for the observed phenotype. Several algorithms are currently available for this purpose, with the most popular being the Model-based Analysis of Genome-wide CRISPR/Cas9 Knockout (MAGeCK) method. Developed specifically for CRISPR/Cas9 knockout screens in 2014, MAGeCK demonstrated better performance compared with alternative algorithms at the time, and has since demonstrated robust results and high sensitivity across different experimental conditions. As of 2015, the MAGeCK algorithm has been extended to introduce quality control measurements, and account for the previously overlooked sgRNA knockout efficiency. A web-based visualisation tool (VISPR) was also integrated, allowing users to interactively explore the results, analysis, and quality controls. | 1 | Applied and Interdisciplinary Chemistry |
All natural products begin as mixtures with other compounds from the natural source, often very complex mixtures, from which the product of interest must be isolated and purified. The isolation of a natural product refers, depending on context, either to the isolation of sufficient quantities of pure chemical matter for chemical structure elucidation, derivitzation/degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but historically, often more), or to the isolation of "analytical quantities" of the substance of interest, where the focus is on identification and quantitation of the substance (e.g. in biological tissue or fluid), and where the quantity isolated depends on the analytical method applied (but is generally always sub-microgram in scale). The ease with which the active agent can be isolated and purified depends on the structure, stability, and quantity of the natural product. The methods of isolation applied toward achieving these two distinct scales of product are likewise distinct, but generally involve extraction, precipitation, adsorptions, chromatography, and sometimes crystallizations. In both cases, the isolated substance is purified to chemical homogeneity, i.e. specific combined separation and analytical methods such as LC-MS methods are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—with the goal being repeated detection of only a single species present in the putative pure sample. Early isolation is almost inevitably followed by structure determination, especially if an important pharmacologic activity is associated with the purified natural product.
Structure determination refers to methods applied to determine the chemical structure of an isolated, pure natural product, a process that involves an array of chemical and physical methods that have changed markedly over the history of natural products research; in earliest days, these focused on chemical transformation of unknown substances into known substances, and measurement of physical properties such as melting point and boiling point, and related methods for determining molecular weight. In the modern era, methods focus on mass spectrometry and nuclear magnetic resonance methods, often multidimensional, and, when feasible, small molecule crystallography. For instance, the chemical structure of penicillin was determined by Dorothy Crowfoot Hodgkin in 1945, work for which she later received a Nobel Prize in Chemistry (1964). | 1 | Applied and Interdisciplinary Chemistry |
Bacteria depend on transcription-translation coupling for genome integrity, termination of transcription and control of mRNA stability. Consequently, artificial disruption of transcription-translation coupling impairs the fitness of bacteria. Without coupling, genome integrity is compromised as stalled transcription complexes interfere with DNA replication and induce DNA breaks. Lack of coupling produces premature transcription termination, likely due to increased binding of termination factor Rho. Degradation of prokaryotic mRNAs is accelerated by loss of coupled translation due to increased availability of target sites of RNase E. It has also been suggested that coupling of transcription with translation is an important mechanism of preventing formation of deleterious R-loops. While transcription-translation coupling is likely prevalent across prokaryotic organisms, not all species are dependent on it. Unlike Escherichia coli, in Bacillus subtilis transcription significantly outpaces translation, and coupling consequently does not occur. | 1 | Applied and Interdisciplinary Chemistry |
The FDA granted Patisiran (Onpattro) orphan drug status and breakthrough therapy designation due to its novel mechanism involving RNA therapy to block the production of an abnormal form of transthyretin. Patisiran received full FDA approval in 2018 and its RNA lipid nanoparticle drug delivery system was later used in the Pfizer–BioNTech COVID-19 vaccine and Moderna RNA vaccines. | 1 | Applied and Interdisciplinary Chemistry |
Yeast artificial chromosome or YAC is a DNA molecule that is developed by humans to take the DNA sequences that belong to yeast cells and clone them. Yeast artificial chromosomes can be inserted with fragments of DNA from the organism of interest. Yeast cells will then assimilate the yeast artificial chromosome that contains the DNA from the organism of interest. The yeast cells then multiply in number and this brings about the amplification of the DNA that has been incorporated into it which is then isolated for the purpose of things like sequencing and mapping of the DNA desired i.e. the DNA originally inserted into the yeast artificial chromosome. Vectorette PCR helps with this process by bringing about not only the isolation of the yeast artificial chromosome’s ends but also the amplification of the ends. | 1 | Applied and Interdisciplinary Chemistry |
One model of Z-ring formation permits its formation only after a certain spatial signal that tells the cell that it is big enough to divide.
The MinCDE system prevents FtsZ polymerization near certain parts of the plasma membrane. MinD localizes to the membrane only at cell poles and contains an ATPase and an ATP-binding domain. MinD is only able to bind to the membrane when in its ATP-bound conformation. Once anchored, the protein polymerizes, resulting in clusters of MinD. These clusters bind and then activate another protein called MinC, which has activity only when bound by MinD.
MinC serves as a FtsZ inhibitor that prevents FtsZ polymerization. The high concentration of a FtsZ polymerization inhibitor at the poles prevents FtsZ from initiating division at anywhere but the mid-cell.
MinE is involved in preventing the formation of MinCD complexes in the middle of the cell. MinE forms a ring near each cell pole. This ring is not like the Z-ring. Instead, it catalyzes the release of MinD from the membrane by activating MinDs ATPase. This hydrolyzes the MinDs bound ATP, preventing it from anchoring itself to the membrane.
MinE prevents the MinD/C complex from forming in the center but allows it to stay at the poles. Once the MinD/C complex is released, MinC becomes inactivated. This prevents MinC from deactivating FtsZ. As a consequence, this activity imparts regional specificity to Min localization.
Thus, FtsZ can form only in the center, where the concentration of the inhibitor MinC is minimal. Mutations that prevent the formation of MinE rings result in the MinCD zone extending well beyond the polar zones, preventing FtsZ to polymerize and to perform cell division.
MinD requires a nucleotide exchange step to re-bind to ATP so that it can re-associate with the membrane after MinE release. The time lapse results in a periodicity of Min association that may yield clues to a temporal signal linked to a spatial signal.
In vivo observations show that the oscillation of Min proteins between cell poles occurs approximately every 50 seconds.
Oscillation of Min proteins, however, is not necessary for all bacterial cell division systems. Bacillus subtilis has been shown to have static concentrations of MinC and MinD at the cell poles.
This system still links cell size to the ability to form a septum via FtsZ and divide. | 1 | Applied and Interdisciplinary Chemistry |
The Pinner triazine synthesis describes the preparation of 2-hydroxyl-4,6-diaryl-s-triazines by reaction of aryl amidines and phosgene. This reaction may be extended to halogenated aliphatic amidines.
This reaction was first reported by Adolf Pinner in 1890 | 0 | Theoretical and Fundamental Chemistry |
Phototendering, i.e., photochemical tendering. As a result of UV light, the substrate material supplies hydrogen to the colourant molecules, reducing the colorant molecule. As the hydrogen is removed, the material undergoes oxidation. | 0 | Theoretical and Fundamental Chemistry |
Many alkyl amines are produced industrially by the amination of alcohols using ammonia in the presence of solid acid catalysts. Illustrative is the production of tert-butylamine:
:NH + CH=C(CH) → HNC(CH)
The Ritter reaction of isobutene with hydrogen cyanide is not useful in this case because it produces too much waste. | 0 | Theoretical and Fundamental Chemistry |
The first clear advantage of chain shuttling is that one can design copolymers with more desirable traits. A polymer that is normally semi crystalline and rigid can be altered so that it has a lower glass transition temperature. An amorphous, elastic polymer membrane can be altered to have a higher melting point. The technique opens the door for tailor-made polymers to be widely accessible and simple to make inexpensively. | 0 | Theoretical and Fundamental Chemistry |
AGEs are responsible for many things. These molecules play an important role especially in nutrition, they are responsible for the brownish color and the aromas and flavors of some foods. It is demonstrated that cooking at high temperature results in various food products having high levels of AGEs.
Having elevated levels of AGEs in the body has a direct impact on the development of many diseases. It has a direct implication in diabetes mellitus type 2 that can lead to many complications such as: cataracts, renal failure, heart damage... And, if they are present at a decreased level, skin elasticity is reduced which is an important symptom of aging.
They are also the precursors of many hormones and regulate and modify their receptor mechanisms at the DNA level. | 0 | Theoretical and Fundamental Chemistry |
The HMG proteins are subdivided into 3 superfamilies each containing a characteristic functional domain:
* HMGA – contains an AT-hook domain
** HMGA1
** HMGA2
* HMGB – contains a HMG-box domain
** HMGB1
** HMGB2
** HMGB3
** HMGB4
* HMGN – contains a nucleosomal binding domain
** HMGN1
** HMGN2
** HMGN3
** HMGN4
** HMGN5
Proteins containing any of these embedded in their sequence are known as HMG motif proteins.
HMG-box proteins are found in a variety of eukaryotic organisms.
They were originally isolated from mammalian cells, and named according to their electrophoretic mobility in polyacrylamide gels. | 1 | Applied and Interdisciplinary Chemistry |
In the late nineteenth century, Pierre Curie was investigating the mysteries of ordinary magnetism when he became aware of the spiritualist experiments of other European scientists, such as Charles Richet and Camille Flammarion. Pierre Curie initially thought the systematic investigation into the paranormal could help with some unanswered questions about magnetism. He wrote to Marie, then his fiancée: "I must admit that those spiritual phenomena intensely interest me. I think they are questions that deal with physics." Pierre Curie's notebooks from this period show he read many books on spiritualism. He did not attend séances such as those of Eusapia Palladino in Paris in June 1905 as a mere spectator, and his goal certainly was not to communicate with spirits. He saw the séances as scientific experiments, tried to monitor different parameters, and took detailed notes of every observation. Despite studying spiritualism, Curie was an atheist. | 1 | Applied and Interdisciplinary Chemistry |
Minze Stuiver was born in Vlagtwedde, the Netherlands, on 25 October 1929. As a boy he narrowly missed being taken into German forced labor toward the end of the Second World War, but, because he was away delivering milk by bicycle, he escaped the round-up that took most of the young men and older boys from the village. His secondary school education was disrupted by the war when the school was occupied by German soldiers and air raids interrupted classes in makeshift rooms. After the war he went to the University of Groningen, where he studied physics, mathematics and astronomy, focusing on nuclear physics. After graduation he joined the biophysics group led by the pre-eminent researcher Hessel de Vries and received a Ph.D. in Biophysics in 1958 with a thesis on the Biophysics of the Sense of Smell. Shortly thereafter he began working in the rapidly developing field of radiocarbon dating with de Vries, who found variations in the concentration of radiocarbon in the atmosphere which challenged the assumptions of the radiocarbon dating method. In 1959, together with his wife, Anneke, Minze went to Yale University for a one-year fellowship position but was called back to Groningen to take over as director of the radiocarbon facility when De Vries died. However Minze chose to remain in the United States at the Geochrometric Laboratory at Yale University. There he developed high-precision methods in radiocarbon that enabled him, along with Hans Suess, to verify De Vries’ “wiggly” nature of the atmospheric concentration of radiocarbon in the past from tree-rings. Stuiver and Suess created one of the first curves for calibration of radiocarbon dates. In 1969 Minze moved to the newly founded Quaternary Research Center at the University of Washington (UW) in Seattle. There he built the Quaternary Isotope Lab with a lead-lined room 30 feet below ground to shield the hand-built gas counters from detecting spurious events due to cosmic rays.
In the 1970s Minze began measuring C in dissolved inorganic carbon in ocean water as part of The Geochemical Ocean Sections Study (GEOSECS) to study the distribution of carbon in the ocean. In addition he was involved in a number of studies on the glacial histories of Antarctica and North America. He was the senior editor of the journal Radiocarbon from 1977 to 1988 and broadened the scope of the publication to include articles about scientific knowledge derived from radiocarbon measurements. By then the terminology for various ways to calculate and present radiocarbon data was becoming rather confusing. Together with Henry Polach, he formulated the equations and conventions for reporting radiocarbon data that is still widely used.
His work investigating atmospheric C changes gave rise to a greater understanding of the changes in solar activity over time and potential links to climate change as well as the extent of fossil fuel input.
In the mid-1980s he led the development of the first high-precision radiocarbon calibration curve extending back nearly 10,000 years ago based on C measurements of tree-rings with known calendar ages from dendrochronology. This data still forms the backbone of the Holocene portion of the current international radiocarbon calibration curve which is used by archaeologists and geoscientists around the world. He also oversaw the development of the CALIB computer software to automate the calibration process.
In the 1990s, in addition to continued work on radiocarbon calibration and solar variability, he began work on oxygen isotopes from Greenland ice cores together with Pieter Grootes. Their sub-annual resolution stable isotopes measurements provided confirmation of the rapid nature of major climatic changes at the end of the last glaciation.
Stuiver died on 26 December 2020, at the age of 91. | 0 | Theoretical and Fundamental Chemistry |
Many substances can form gels when a suitable thickener or gelling agent is added to their formula. This approach is common in manufacture of wide range of products, from foods to paints and adhesives.
In fiber optic communications, a soft gel resembling hair gel in viscosity is used to fill the plastic tubes containing the fibers. The main purpose of the gel is to prevent water intrusion if the buffer tube is breached, but the gel also buffers the fibers against mechanical damage when the tube is bent around corners during installation, or flexed. Additionally, the gel acts as a processing aid when the cable is being constructed, keeping the fibers central whilst the tube material is extruded around it. | 0 | Theoretical and Fundamental Chemistry |
The NS radical is a highly transient species, with a lifetime on the order of milliseconds, but it can be observed spectroscopically over short periods of time through several methods of generation. NS is too reactive to isolate as a solid or liquid, and has only been prepared as a vapor in low pressure or low-temperature matrices due to its tendency to rapidly oligomerize to more stable, diamagnetic species. | 0 | Theoretical and Fundamental Chemistry |
Depending on the relationship between shear stress and the rate of strain and its derivatives, fluids can be characterized as one of the following:
*Newtonian fluids: where stress is directly proportional to rate of strain
*Non-Newtonian fluids: where stress is not proportional to rate of strain, its higher powers and derivatives.
Newtonian fluids follow Newton's law of viscosity and may be called viscous fluids.
Fluids may be classified by their compressibility:
*Compressible fluid: A fluid that causes volume reduction or density change when pressure is applied to the fluid or when the fluid becomes supersonic.
*Incompressible fluid: A fluid that does not vary in volume with changes in pressure or flow velocity (i.e., ρ=constant) such as water or oil.
Newtonian and incompressible fluids do not actually exist, but are assumed to be for theoretical settlement. Virtual fluids that completely ignore the effects of viscosity and compressibility are called perfect fluids. | 1 | Applied and Interdisciplinary Chemistry |
The consequences of having no inertial terms at low Reynolds number are:
* One consequence means that the swimmer experiences virtually no net force or torque.
* A second consequence tells us that the velocity is linearly proportional to the force (same can be said about angular velocity and torque).
* The Stokes equations become are linear and independent of time.
In particular, for a swimmer moving in the low Reynolds number regime, its motion satisfies:
* Independent of time: The same motion may be sped up or slowed down, and it would still satisfy the Stokes equations. More geometrically, this means that the motion of a swimmer in the low Reynolds number regime is purely determined by the shape of its trajectory in configuration space.
* Kinematic reversibility: The same motion may be reversed. Any instantaneous reversal of the forces acting on the body will not change the nature of the fluid flow around it, simply the direction of the flow. These forces are responsible for producing motion. When a body has only one degree of freedom, reversal of forces will cause the body to deform in a reciprocal fashion. For instance, a scallop opening its hinge will simply close it to try to achieve propulsion. Since the reversal of forces does not change the nature of the flow, the body will move in the reverse direction in the exact same manner, leading to no net displacement. This is how we arrive at the consequences of the scallop theorem. | 1 | Applied and Interdisciplinary Chemistry |
The New Zealand Environmental Protection Agency (EPA) has banned the use of per- and polyfluoroalkyl substances (PFAS) in cosmetic products starting from 31st December 2026. This will make the country one of the first in the world to take this step on PFAS to protect people and the environment. | 0 | Theoretical and Fundamental Chemistry |
A protein subunit is a polypeptide chain or protein molecule that assembles (or "coassembles") with other protein molecules to form a protein complex. Large assemblies of proteins such as viruses often use a small number of types of protein subunits as building blocks. A key step in creating a recombinant protein vaccine is the identification and isolation of a protein subunit from the pathogen which is likely to trigger a strong and effective immune response, without including the parts of the virus or bacterium that enable the pathogen to reproduce. Parts of the protein shell or capsid of a virus are often suitable. The goal is for the protein subunit to prime the immune system response by mimicking the appearance but not the action of the pathogen. Another protein-based approach involves self‐assembly of multiple protein subunits into a virus-like particle (VLP) or nanoparticle. The purpose of increasing the vaccine's surface similarity to a whole virus particle (but not its ability to spread) is to trigger a stronger immune response.
Protein subunit vaccines are generally made through protein production, manipulating the gene expression of an organism so that it expresses large amounts of a recombinant gene. A variety of approaches can be used for development depending on the vaccine involved. Yeast, baculovirus, or mammalian cell cultures can be used to produce large amounts of proteins in vitro.
Protein-based vaccines are being used for hepatitis B and for human papillomavirus (HPV). The approach is being used to try to develop vaccines for difficult-to-vaccinate-against viruses such as ebolavirus and HIV. Protein-based vaccines for COVID-19 tend to target either its spike protein or its receptor binding domain. As of 2021, the most researched vaccine platform for COVID-19 worldwide was reported to be recombinant protein subunit vaccines. | 1 | Applied and Interdisciplinary Chemistry |
Arsenic exposure through groundwater is highly concerning throughout the perinatal period. Pregnant women are a high-risk population because not only are the mothers at risk for adverse outcomes, but in-utero exposure also poses health risks to the infant.
There is a dose-dependent relationship between maternal exposure to arsenic and infant mortality, meaning that infants born to women exposed to higher concentrations, or exposed for longer periods of time, have a higher mortality rate.
Studies have shown that ingesting arsenic through groundwater during pregnancy poses dangers to the mother including, but not limited to abdominal pain, vomiting, diarrhea, skin pigmentation changes, and cancer. Research has also demonstrated that arsenic exposure also causes low birth weight, low birth size, infant mortality, and a variety of other outcomes in infants. Some of these effects, like lower birth-rate and size may be due to the effects of arsenic on maternal weight gain during pregnancy. | 1 | Applied and Interdisciplinary Chemistry |
AOAC International holds an Annual Meeting & Conference, typically held in August or September of each year, which is moved around the United States and held in major cities. In addition, a mid-year meeting is held every March near the headquarters in Rockville, Maryland. | 0 | Theoretical and Fundamental Chemistry |
Methylation, in the chemical sciences, is the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These terms are commonly used in chemistry, biochemistry, soil science, and biology.
In biological systems, methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA processing. In vitro methylation of tissue samples is also a way to reduce some histological staining artifacts. The reverse of methylation is demethylation. | 0 | Theoretical and Fundamental Chemistry |
Total RNA is purified from the specimen of interest. Poly A messenger RNA is then purified from total RNA and subsequently translated into cDNA using a reverse transcription reaction. The cDNA produced from the mRNA is labeled using primers homologous to the spliced leader sequences of the organism. In a nine step PCR reaction the cDNAs are concurrently embedded with the BpmI restriction endonuclease site (though any class IIs restriction endonuclease may work) and a biotin label which are present in the primers. These tagged cDNAs are then cleaved 14 bp downstream from the recognition site using BpmI restriction endonuclease and blunt ended with T4 DNA polymerase. The fragments are further purified away from extraneous DNA material by using the biotin labels to bind them to a strepdavidin matrix. They are then ligated to adapter DNA, in six separate reactions, containing six different restriction endonuclease recognition sites. These tags are then amplified by PCR with primers containing a mismatch changing the Bpm1 site to a Xho1 site. The amplicons are concatenated and ligated into a plasmid vector. The clonal vectors are then sequenced and mapped to the genome. | 1 | Applied and Interdisciplinary Chemistry |
The relation between the change in Gibbs reaction energy and Gibbs energy can be defined as the slope of the Gibbs energy plotted against the extent of reaction at constant pressure and temperature.
This formula leads to the Nernst equation when applied to the oxidation-reduction reaction which generates the voltage of a voltaic cell. Analogously, the relation between the change in reaction enthalpy and enthalpy can be defined. For example, | 0 | Theoretical and Fundamental Chemistry |
Some histidine kinases are hybrids that contain an internal receiver domain. In these cases, a hybrid HK autophosphorylates and then transfers the phosphoryl group to its own internal receiver domain, rather than to a separate RR protein. The phosphoryl group is then shuttled to histidine phosphotransferase (HPT) and subsequently to a terminal RR, which can evoke the desired response. This system is called a phosphorelay. Almost 25% of bacterial HKs are of the hybrid type, as are the large majority of eukaryotic HKs. | 1 | Applied and Interdisciplinary Chemistry |
Superfluidity was discovered in helium-4 by Pyotr Kapitsa and independently by John F. Allen and Don Misener in 1937. Onnes possibly observed the superfluid phase transition on August 2 1911, the same day that he observed superconductivity in mercury. It has since been described through phenomenology and microscopic theories.
In liquid helium-4, the superfluidity occurs at far higher temperatures than it does in helium-3. Each atom of helium-4 is a boson particle, by virtue of its integer spin. A helium-3 atom is a fermion particle; it can form bosons only by pairing with another particle like itself at much lower temperatures. The discovery of superfluidity in helium-3 was the basis for the award of the 1996 Nobel Prize in Physics. This process is similar to the electron pairing in superconductivity. | 0 | Theoretical and Fundamental Chemistry |
Triple-decker complexes are known to obey a 30-valence electron (VE) rule. Subtracting 6 pairs of nonbonding electrons from the two metal atoms brings the number of SEPs to 9 pairs. For a triple-decker complex with cyclopentadienyl| as the decks, m + n + o + p − q = 3 + 17 + 2 + 2 − 0 = 24. Subtracting the 15 pairs corresponding to C–C sigma bonds, it becomes 9 pairs. For example, consider : 15 C–CH groups provide pairs. Each ruthenium atom provides one pair. Removing the electron corresponding to the positive charge of the complex leads to a total of + 2 − = 24 pairs. | 0 | Theoretical and Fundamental Chemistry |
In pre-modern chemistry and alchemy, cohobation was the process of repeated distillation of the same matter, with the liquid drawn from it; that liquid being poured again and again upon the matter left at the bottom of the vessel. Cohobation is a kind of circulation, only differing from it in this, that the liquid is drawn off in cohobation, as in common distillation, and thrown back again; whereas in circulation, it rises and falls in the same vessel, without ever being drawn out.
Cohobation has no corresponding process in modern chemistry, as it is not a useful process. Indeed, it is equivalent to performing the same distillation a number of times and does not increase the purity of the distillate or alter the residue any more than would be done by maintaining it at elevated temperature for the same period of time. The Dean-Stark trap does involve returning some distillate to the reaction flask: a solution is distilled and the condensed liquid is collected in a tube wherein water settles to the bottom and is drained out, while an organic solvent returns to the boiling solution. However, the process is not manual, most of the solvent does not leave the reaction flask, and the apparatus achieves a useful purpose (removing water from the reaction mixture). Circulation, on the other hand, is approximately the same as reflux, where a solution is maintained at its boiling point by condensing the distilling vapors and returning them directly to the reaction mixture. | 1 | Applied and Interdisciplinary Chemistry |
Cell–cell interactions are highly specific and are tightly regulated. Genetic defects and dysregulation of these interactions can cause many different diseases. Dysregulation that leads to leukocyte migration into healthy tissues can cause conditions such as acute respiratory distress syndrome and some types of arthritis. The autoimmune disease pemphigus vulgaris results from autoantibodies to desmoglein and other normal body proteins. The autoantibodies disrupt the adhesion between epithelial cells. This causes blisters of the skin and mucous membranes. Mutations in the connexin genes cause 8 human diseases including heart malformations and neurosensory deafness. | 1 | Applied and Interdisciplinary Chemistry |
The moisture sorption properties of pharmaceutical materials such as excipients, drug formulations and packaging films are recognized as critical factors in determining their storage, stability, processing and application performance. Further, vapor sorption experiments can be used to study hydrate and solvate formation. Gravimetric vapor sorption experiments are one of the most sensitive methods for determining amorphous contents, which may have a detrimental impact on the stability, manufacturability and dissolution characteristics of the formulated drug product. | 0 | Theoretical and Fundamental Chemistry |
Many types of solid materials can exhibit more than one mechanism for DNP. Some examples are carbonaceous materials such bituminous coal and charcoal (wood or cellulose heated at high temperatures above their decomposition point which leaves a residual solid char). To separate out the mechanisms of DNP and to characterize the electron-nuclear interactions occurring in such solids a DNP enhancement curve can be made. A typical enhancement curve is obtained by measuring the maximum intensity of the NMR FID of the H nuclei, for example, in the presence of continuous microwave irradiation as a function of the microwave frequency offset.
Carbonaceous materials such as cellulose char contain large numbers of stable free electrons delocalized in large polycyclic aromatic hydrocarbons. Such electrons can give large polarization enhancements to nearby protons via proton-proton spin-diffusion if they are not so close together that the electron-nuclear dipolar interaction does not broaden the proton resonance beyond detection. For small isolated clusters, the free electrons are fixed and give rise to solid-state enhancements (SS). The maximal proton solid-state enhancement is observed at microwave offsets of ω ≈ ω ± ω, where ω and ω are the electron and nuclear Larmor frequencies, respectively. For larger and more densely concentrated aromatic clusters, the free electrons can undergo rapid electron exchange interactions. These electrons give rise to an Overhauser enhancement centered at a microwave offset of ω – ω = 0. The cellulose char also exhibits electrons undergoing thermal mixing effects (TM). While the enhancement curve reveals the types electron-nuclear spin interactions in a material, it is not quantitative and the relative abundance of the different types of nuclei cannot be determined directly from the curve. | 0 | Theoretical and Fundamental Chemistry |
New drugs are the products of a long drug development process, the first step of which is often the discovery of a new enzyme inhibitor. There are two principle approaches of discovering these inhibitors.
The first general method is rational drug design based on mimicking the transition state of the chemical reaction catalysed by the enzyme. The designed inhibitor often closely resembles the substrate, except that the portion of the substrate that undergoes chemical reaction is replaced by a chemically stable functional group that resembles the transition state. Since the enzyme has evolved to stabilise the transition state, transition state analogues generally possess higher affinity for the enzyme compared to the substrate, and therefore are effective inhibitors.
The second way of discovering new enzyme inhibitors is high-throughput screening of large libraries of structurally diverse compounds to identify hit molecules that bind to the enzyme. This method has been extended to include virtual screening of databases of diverse molecules using computers, which are then followed by experimental confirmation of binding of the virtual screening hits. Complementary approaches that can provide new starting points for inhibitors include fragment-based lead discovery and DNA Encoded Chemical Libraries (DEL).
Hits from any of the above approaches can be optimised to high affinity binders that efficiently inhibit the enzyme. Computer-based methods for predicting the binding orientation and affinity of an inhibitor for an enzyme such as molecular docking and molecular mechanics can be used to assist in the optimisation process. New inhibitors are used to obtain crystallographic structures of the enzyme in an inhibitor/enzyme complex to show how the molecule is binding to the active site, allowing changes to be made to the inhibitor to optimise binding in a process known as structure-based drug design. This test and improve cycle is repeated until a sufficiently potent inhibitor is produced. | 1 | Applied and Interdisciplinary Chemistry |
Cefalexin, also spelled cephalexin, is an antibiotic that can treat a number of bacterial infections. It kills gram-positive and some gram-negative bacteria by disrupting the growth of the bacterial cell wall. Cefalexin is a β-lactam antibiotic within the class of first-generation cephalosporins. It works similarly to other agents within this class, including intravenous cefazolin, but can be taken by mouth.
Cefalexin can treat certain bacterial infections, including those of the middle ear, bone and joint, skin, and urinary tract. It may also be used for certain types of pneumonia and strep throat and to prevent bacterial endocarditis. Cefalexin is not effective against infections caused by methicillin-resistant Staphylococcus aureus (MRSA), most Enterococcus, or Pseudomonas. Like other antibiotics, cefalexin cannot treat viral infections, such as the flu, common cold or acute bronchitis. Cefalexin can be used in those who have mild or moderate allergies to penicillin. However, it is not recommended in those with severe penicillin allergies.
Common side effects include stomach upset and diarrhea. Allergic reactions or infections with Clostridium difficile, a cause of diarrhea, are also possible. Use during pregnancy or breast feeding does not appear to be harmful to the fetus. It can be used in children and those over 65 years of age. Those with kidney problems may require a decrease in dose.
Cefalexin was developed in 1967. It was first marketed in 1969 and 1970 under the names Keflex and Ceporex, among others. Generic drug versions are available under other trade names and are inexpensive. It is on the World Health Organization's List of Essential Medicines. In 2021, it was the 96th most commonly prescribed medication in the United States, with more than 7million prescriptions. In Canada, it was the fifth most common antibiotic used in 2013. In Australia, it is one of the top 15 most prescribed medications. | 0 | Theoretical and Fundamental Chemistry |
Xylenol orange is an organic reagent, most commonly used as a tetrasodium salt as an indicator for metal titrations. When used for metal titrations, it will appear red in the titrand and become yellow once it reaches its endpoint. Historically, commercial preparations of it have been notoriously impure, sometimes consisting of as little as 20% xylenol orange, and containing large amounts of semi-xylenol orange and iminodiacetic acid. Purities as high as 90% are now available.
It is fluorescent, and has excitation maximums of 440 & 570 nm and an emission maximum of 610 nm. | 0 | Theoretical and Fundamental Chemistry |
Depending on how the experiment is carried out, DamID can be subject to plasmid methylation biases. Because plasmids are usually amplified in E. coli where Dam is naturally expressed, they are methylated on every GATC. In transient transfection experiments, the DNA of those plasmids is recovered along with the DNA of the transfected cells, meaning that fragments of the plasmid are amplified in the methyl PCR. Every sequence of the genome that shares homology or identity with the plasmid may thus appear to be bound by the protein of interest. In particular, this is true of the open reading frame of the protein of interest, which is present in both the plasmid and the genome. In microarray experiments, this bias can be used to ensure that the proper material was hybridized. In stable cell lines or fully transgenic animals, this bias is not observed as no plasmid DNA is recovered. | 1 | Applied and Interdisciplinary Chemistry |
Reverse electron flow is the transfer of electrons through the electron transport chain through the reverse redox reactions. Usually requiring a significant amount of energy to be used, this can reduce the oxidized forms of electron donors. For example, NAD can be reduced to NADH by Complex I. There are several factors that have been shown to induce reverse electron flow. However, more work needs to be done to confirm this. One example is blockage of ATP synthase, resulting in a build-up of protons and therefore a higher proton-motive force, inducing reverse electron flow. | 1 | Applied and Interdisciplinary Chemistry |
Tris-buffered saline (TBS) is a buffer used in some biochemical techniques to maintain the pH within a relatively narrow range. Tris (with HCl) has a slightly alkaline buffering capacity in the 7–9.2 range. The conjugate acid of Tris has a pK of 8.07 at 25 °C. The pK declines approximately 0.03 units per degree Celsius rise in temperature. This can lead to relatively dramatic pH shifts when there are shifts in solution temperature. Sodium chloride concentration may vary from 100 to 200 mM, tris concentration from 5 to 100 mM and pH from 7.2 to 8.0. A common formulation of TBS is 150 mM NaCl, 50 mM Tris-HCl, pH 7.6. TBS can also be prepared by using commercially made TBS buffer tablets or pouches. | 1 | Applied and Interdisciplinary Chemistry |
The saturation state (known as Ω) of seawater for a mineral is a measure of the thermodynamic potential for the mineral to form or to dissolve, and for calcium carbonate is described by the following equation:
Here Ω is the product of the concentrations (or activities) of the reacting ions that form the mineral (Ca and CO), divided by the apparent solubility product at equilibrium (K), that is, when the rates of precipitation and dissolution are equal. In seawater, dissolution boundary is formed as a result of temperature, pressure, and depth, and is known as the saturation horizon. Above this saturation horizon, Ω has a value greater than 1, and does not readily dissolve. Most calcifying organisms live in such waters. Below this depth, Ω has a value less than 1, and will dissolve. The carbonate compensation depth is the ocean depth at which carbonate dissolution balances the supply of carbonate to sea floor, therefore sediment below this depth will be void of calcium carbonate. Increasing levels, and the resulting lower pH of seawater, decreases the concentration of CO and the saturation state of therefore increasing dissolution.
Calcium carbonate most commonly occurs in two common polymorphs (crystalline forms): aragonite and calcite. Aragonite is much more soluble than calcite, so the aragonite saturation horizon, and aragonite compensation depth, is always nearer to the surface than the calcite saturation horizon. This also means that those organisms that produce aragonite may be more vulnerable to changes in ocean acidity than those that produce calcite. Ocean acidification and the resulting decrease in carbonate saturation states raise the saturation horizons of both forms closer to the surface. This decrease in saturation state is one of the main factors leading to decreased calcification in marine organisms because the inorganic precipitation of is directly proportional to its saturation state and calcifying organisms exhibit stress in waters with lower saturation states. | 0 | Theoretical and Fundamental Chemistry |
Cyanobacteria have fundamentally transformed the geochemistry of the planet. Multiple lines of geochemical evidence support the occurrence of intervals of profound global environmental change at the beginning and end of the Proterozoic (2,500–542 Mya).
While it is widely accepted that the presence of molecular oxygen in the early fossil record was the result of cyanobacteria activity, little is known about how cyanobacteria evolution (e.g., habitat preference) may have contributed to changes in biogeochemical cycles through Earth history. Geochemical evidence has indicated that there was a first step-increase in the oxygenation of the Earths surface, which is known as the Great Oxidation Event (GOE), in the early Paleoproterozoic (2,500–1,600 Mya). A second but much steeper increase in oxygen levels, known as the Neoproterozoic Oxygenation Event (NOE), occurred at around 800 to 500 Mya. Recent chromium isotope data point to low levels of atmospheric oxygen in the Earths surface during the mid-Proterozoic, which is consistent with the late evolution of marine planktonic cyanobacteria during the Cryogenian; both types of evidence help explain the late emergence and diversification of animals.
Understanding the evolution of planktonic cyanobacteria is important because their origin fundamentally transformed the nitrogen and carbon cycles towards the end of the Pre-Cambrian. It remains unclear, however, what evolutionary events led to the emergence of open-ocean planktonic forms within cyanobacteria and how these events relate to geochemical evidence during the Pre-Cambrian. So far, it seems that ocean geochemistry (e.g., euxinic conditions during the early- to mid-Proterozoic) and nutrient availability likely contributed to the apparent delay in diversification and widespread colonization of open ocean environments by planktonic cyanobacteria during the Neoproterozoic. | 0 | Theoretical and Fundamental Chemistry |
Until 1980, laser-heated crystal growth used only two laser beams focused over the source material. This condition generated a high radial thermal gradient in the molten zone, making the process unstable. Increasing the number of beams to four did not solve the problem, although it improved the growth process.
An improvement to the laser-heated crystal growth technique was made by Fejer et al., who incorporated a special optical component known as a reflaxicon, consisting of an inner cone surrounded by a larger coaxial cone section, both with reflecting surfaces. This optical element converts the cylindrical laser beam into a larger diameter hollow cylinder surface. This optical component allows radial distribution of the laser energy over the molten zone, reducing radial thermal gradients. The axial temperature gradient in this technique can go as high as 10000 °C/cm, which is very high when compared to traditional crystal growth techniques (10–100 °C/cm). | 0 | Theoretical and Fundamental Chemistry |
During the 1990s, the lactic acid hypothesis was created to explain why people experienced burning or muscle cramps that occurred during and after intense exercise. The hypothesis proposes that a lack of oxygen in muscle cells results in a switch from cellular respiration to fermentation. Lactic acid created as a byproduct of fermentation of pyruvate from glycolysis accumulates in muscles causing a burning sensation and cramps.
Research from 2006 has suggested that acidosis isn't the main cause of muscle cramps. Instead cramps may be due to a lack of potassium in muscles, leading to contractions under high stress.
Animals, in fact, do not produce lactic acid during fermentation. Despite the common use of the term lactic acid in the literature, the byproduct of fermentation in animal cells is lactate.
Another change to the lactic acid hypothesis is that when sodium lactate is inside of the body, there is a higher period of exhaustion in the host after a period of exercise.
Lactate fermentation is important to muscle cell physiology. When muscle cells are undergoing intense activity, like sprinting, they need energy quickly. There is only enough ATP stored in muscles cells to last a few seconds of sprinting. The cells then default to fermentation, since they are in an anaerobic environment. Through lactate fermentation, muscle cells are able to regenerate NAD+ to continue glycolysis, even under strenuous activity. [5]
The vaginal environment is heavily influenced by lactic acid producing bacteria. Lactobacilli spp. that live in the vaginal canal assist in pH control. If the pH in the vagina becomes too basic, more lactic acid will be produced to lower the pH back to a more acidic level. Lactic acid producing bacteria also act as a protective barrier against possible pathogens such as bacterial vaginosis and vaginitis species, different fungi, and protozoa through the production of hydrogen peroxide, and antibacterial compounds. It is unclear if further use of lactic acid, through fermentation, in the vaginal canal is present [6] | 1 | Applied and Interdisciplinary Chemistry |
The term ‘secondary building unit’ has been used for some time to describe conceptual fragments which can be compared as bricks used to build a house of zeolites; in the context of this page it refers to the geometry of the units defined by the points of extension. | 0 | Theoretical and Fundamental Chemistry |
Aliphatic diisocyanates are not used in the production of polyurethane foam as the cost is too high and foam is very much a commodity. It is used in special applications for polyurethane, such as enamel coatings which are resistant to abrasion and degradation from ultraviolet light. There are also multiple patents where prepolymers based on it are used in golf ball production. It is available commercially under the tradename of Desmodur W from Covestro - formerly Bayer Material Science. It is used as a reactive building block for the preparation of other chemical products such as isocyanate terminated prepolymers and other urethane polymers. The isocyanate groups can undergo addition reactions at room temperature with compounds which contain active hydrogens especially amines and polyols. Polyurethane resins based on this diisocyanate have good flexibility and mechanical strength. The polymers formed tend to have abrasion and hydrolysis resistance as well as retaining gloss and physical properties upon weathering. The resins based on this material are useful in coatings for flooring, roofing, maintenance and adhesives, and sealants. They find use in the coatings, adhesives, sealants and elastomers (CASE) applications. A prepolymer made from HMDI and incorporating dimethylol propionic acid can also be converted to light stable polyurethane dispersions. | 0 | Theoretical and Fundamental Chemistry |
In some cases, discordant reads can also indicate a CNV for example in sequences repeats. For larger CNV, the density of the reads will vary accordingly to the copy number. An increase of copy numbers will be reflected by increasing mapping of the same region on the reference genome. | 1 | Applied and Interdisciplinary Chemistry |
Forced convection is a mechanism, or type of transport, in which fluid motion is generated by an external source (like a pump, fan, suction device, etc.). Alongside natural convection, thermal radiation, and thermal conduction it is one of the methods of heat transfer and allows significant amounts of heat energy to be transported very efficiently. | 0 | Theoretical and Fundamental Chemistry |
Sialic acid containing glycoproteins (sialoglycoproteins) bind selectin in humans and other organisms. Metastatic cancer cells often express a high density of sialic acid-rich glycoproteins. This overexpression of sialic acid on surfaces creates a negative charge on cell membranes. This creates repulsion between cells (cell opposition) and helps these late-stage cancer cells enter the blood stream. Recent experiments have demonstrated the presence of sialic acid in the cancer-secreted extracellular matrix.
Sialic acid-rich oligosaccharides on the glycoconjugates (glycolipids, glycoproteins, proteoglycans) found on surface membranes help keep water at the surface of cells. The sialic acid-rich regions contribute to creating a negative charge on the cells' surfaces. Since water is a polar molecule with partial positive charges on both hydrogen atoms, it is attracted to cell surfaces and membranes. This also contributes to cellular fluid uptake.
Sialic acid residues are present in the mucin glycoproteins of mucus.
Sialic acid can "hide" mannose antigens on the surface of host cells or bacteria from mannose-binding lectin. This prevents activation of complement.
Sialic acid in the form of polysialic acid is an unusual posttranslational modification that occurs on the neural cell adhesion molecules (NCAMs). In the synapse, the strong negative charge of the polysialic acid prevents NCAM cross-linking of cells.
Administration of estrogen to castrated mice leads to a dose-dependent reduction of the sialic acid content of the vagina. Conversely, the sialic acid content of mouse vagina is a measure of the potency of the estrogen. Reference substances are estradiol for subcutaneous application and ethinylestradiol for oral administration. | 0 | Theoretical and Fundamental Chemistry |
Upon first arriving in the Philippine archipelago, landing specifically in the visayas, Spanish colonizers noted astonishing amounts of gold in common use, including earrings, armbands legbands, gold chains, collars of beads, wristlets, armlets, finger rings, and so on. They were also integrated into clothing as sequins, as clasps or buttons for cloaks or as broaches. | 1 | Applied and Interdisciplinary Chemistry |
The term "apothecary" derives from the Ancient Greek (, "a repository, storehouse") via Latin ("repository, storehouse, warehouse", cf. and ), Medieval Latin ("storekeeper"), and eventually Old French .
In some European and other languages, the term is current and used to designate a pharmacist/chemist, such as Dutch and German , Hungarian , Irish , Latvian and Luxembourgish . Likewise, "pharmacy" translates as in Danish, Norwegian and Swedish, in Finnish, in Bosnian, in Hungarian, in Latvian, () in Serbian, () in Russian, Bulgarian, Macedonian and Ukrainian, in German and in Polish. The word in Indonesian is , which was borrowed from the Dutch . In Yiddish the word is .
Use of the term in the names of businesses varies with time and location. It is generally an Americanism, though some areas of the United States use it to invoke an experience of nostalgic revival and it has been used for a wide variety of businesses; while in other areas such as California its use is restricted to licensed pharmacies. | 1 | Applied and Interdisciplinary Chemistry |
Soap bubbles have been used as entertainment for at least 400 years, as evidenced by 17th-century Flemish paintings showing children blowing bubbles with clay pipes. The London-based firm A. & F. Pears created a famous advertising campaign for its soaps in 1886 using a painting by John Everett Millais of a child playing with bubbles. The Chicago company Chemtoy began selling bubble solution in the 1940s, and bubble solution has been popular with children ever since. According to one industry estimate, retailers sell around 200 million bottles annually. | 1 | Applied and Interdisciplinary Chemistry |
A variety of complexes - a subset of metallaborane - are known with one or two dicarbollide ligands. An example of a 1:1 complex is [Mn(CO)(η-7,8-CBH)].
Most heavily studied are complexes with two dicarbollide ligands, especially sandwich complexes. Thus, these are prepared by salt metathesis reactions, as illustrated by the synthesis of the ferrocene analogue:
:2 NaCBH + FeCl → Na[Fe(CBH)] + 2 NaCl
These bisdicarbollide dianions are often readily oxidized. Fe(III), Co(III), Ni(III), and Ni(IV) derivatives are known. In some cases, the oxidation induces rearrangement of the CB cage to give complexes where the carbon centers are nonadjacent. | 0 | Theoretical and Fundamental Chemistry |
The stockpiles, which have been maintained for more than 50 years, are now considered obsolete. Public Law 99-145, contains section 1412, which directs the Department of Defense (DOD) to dispose of the stockpiles. This directive fell upon the DOD with joint cooperation from the Federal Emergency Management Agency (FEMA). The Congressional directive has resulted in the present Chemical Stockpile Disposal Program.
Historically, chemical munitions have been disposed of by land burial, open burning, and ocean dumping (referred to as Operation CHASE). However, in 1969, the National Research Council (NRC) recommended that ocean dumping be discontinued. The Army then began a study of disposal technologies, including the assessment of incineration as well as chemical neutralization methods. In 1982, that study culminated in the selection of incineration technology, which is now incorporated into what is known as the baseline system. Construction of the Johnston Atoll Chemical Agent Disposal System (JACADS) began in 1985.
This was to be a full-scale prototype facility using the baseline system. The prototype was a success but there were still many concerns about CONUS operations. To address growing public concern over incineration, Congress, in 1992, directed the Army to evaluate alternative disposal approaches that might be "significantly safer", more cost effective, and which could be completed within the established time frame. The Army was directed to report to Congress on potential alternative technologies by the end of 1993, and to include in that report: "any recommendations that the National Academy of Sciences makes ..." In June 2007, the disposal program achieved the milestone of reaching 45% destruction of the chemical weapon stockpile. The Chemical Materials Agency (CMA) releases regular updates to the public regarding the status of the disposal program. On July 7, 2023, the program completed destruction of all declared chemical weapons. | 1 | Applied and Interdisciplinary Chemistry |
Yusif Haydar oglu Mammadaliyev (; December 31, 1905 – December 15, 1961) was an Azerbaijani and Soviet chemist. He was a Doctor of Chemistry, academician of the National Academy of Sciences of the Azerbaijan SSR, and was the president of the National Academy of Sciences of the Azerbaijan SSR.
According to the statement of the 4th President of Azerbaijan, Ilham Aliyev , he is the inventor of the incendiary mixture that became known as the “Molotov cocktail”. | 0 | Theoretical and Fundamental Chemistry |
Independent of the developments for electrons in vacuum, at about the same time the components of quantum mechanics were being assembled. In 1924 Louis de Broglie in his PhD thesis Recherches sur la théorie des quanta introduced his theory of electron waves. He suggested that an electron around a nucleus could be thought of as standing waves, and that electrons and all matter could be considered as waves. He merged the idea of thinking about them as particles (or corpuscles), and of thinking of them as waves. He proposed that particles are bundles of waves (wave packets) that move with a group velocity and have an effective mass, see for instance Figure 4. Both of these depend upon the energy, which in turn connects to the wavevector and the relativistic formulation of Albert Einstein a few years before.
This rapidly became part of what was called by Erwin Schrödinger undulatory mechanics, now called the Schrödinger equation or wave mechanics. As stated by Louis de Broglie on September 8, 1927, in the preface to the German translation of his theses (in turn translated into English):
The Schrödinger equation combines the kinetic energy of waves and the potential energy due to, for electrons, the Coulomb potential. He was able to explain earlier work such as the quantization of the energy of electrons around atoms in the Bohr model, as well as many other phenomena. Electron waves as hypothesized by de Broglie were automatically part of the solutions to his equation, see also introduction to quantum mechanics and matter waves.
Both the wave nature and the undulatory mechanics approach were experimentally confirmed for electron beams by experiments from two groups performed independently, the first the Davisson–Germer experiment, the other by George Paget Thomson and Alexander Reid; see note for more discussion. Alexander Reid, who was Thomsons graduate student, performed the first experiments, but he died soon after in a motorcycle accident and is rarely mentioned. These experiments were rapidly followed by the first non-relativistic diffraction model for electrons by Hans Bethe based upon the Schrödinger equation, which is very close to how electron diffraction is now described. Significantly, Clinton Davisson and Lester Germer noticed that their results could not be interpreted using a Braggs law approach as the positions were systematically different; the approach of Hans Bethe which includes the refraction due to the average potential yielded more accurate results. These advances in understanding of electron wave mechanics were important for many developments of electron-based analytical techniques such as Seishi Kikuchi's observations of lines due to combined elastic and inelastic scattering, gas electron diffraction developed by Herman Mark and Raymond Weil, diffraction in liquids by Louis Maxwell, and the first electron microscopes developed by Max Knoll and Ernst Ruska. | 0 | Theoretical and Fundamental Chemistry |
In response to the criticism that the Gaia hypothesis seemingly required unrealistic group selection and cooperation between organisms, James Lovelock and Andrew Watson developed a mathematical model, Daisyworld, in which ecological competition underpinned planetary temperature regulation.
Daisyworld examines the energy budget of a planet populated by two different types of plants, black daisies and white daisies, which are assumed to occupy a significant portion of the surface. The colour of the daisies influences the albedo of the planet such that black daisies absorb more light and warm the planet, while white daisies reflect more light and cool the planet. The black daisies are assumed to grow and reproduce best at a lower temperature, while the white daisies are assumed to thrive best at a higher temperature. As the temperature rises closer to the value the white daisies like, the white daisies outreproduce the black daisies, leading to a larger percentage of white surface, and more sunlight is reflected, reducing the heat input and eventually cooling the planet. Conversely, as the temperature falls, the black daisies outreproduce the white daisies, absorbing more sunlight and warming the planet. The temperature will thus converge to the value at which the reproductive rates of the plants are equal.
Lovelock and Watson showed that, over a limited range of conditions, this negative feedback due to competition can stabilize the planets temperature at a value which supports life, if the energy output of the Sun changes, while a planet without life would show wide temperature changes. The percentage of white and black daisies will continually change to keep the temperature at the value at which the plants reproductive rates are equal, allowing both life forms to thrive.
It has been suggested that the results were predictable because Lovelock and Watson selected examples that produced the responses they desired. | 0 | Theoretical and Fundamental Chemistry |
An example of the implementation of the IVB approach was in the engineering of autologous bone by injecting calcium alginate in a sub-periosteal location. The periosteum is a membrane that covers the long bones, jawbone, ribs and the skull. This membrane contains an endogenous population of pluripotent cells called the periosteal cells, which are a type of mesenchymal stem cells (MSC), which reside in the cambium layer, i.e., the side facing the bone. A key step in the procedure is the elevation of the periosteum without damaging the cambium surface and to ensure this a new technique called hydraulic elevation was developed.
The choice of the sub-periosteum site is used because stimulation of the cambium layer using transforming growth factor–beta resulted in enhanced chondrogenesis, i.e., formation of cartilage. In development the formation of bone can either occur via a Cartilage template initially formed by the MSCs that then gets ossified through a process called endochondral ossification or directly from MSC differentiation to bone via a process termed intra-membranous ossification. Upon exposure of the periosteal cells to calcium from the alginate gel, these cells become bone cells and start producing bone matrix through the intra-membranous ossification process, recapitulating all steps of bone matrix deposition. The extension of the IVB paradigm to engineering autologous hyaline cartilage was also recently demonstrated. In this case, agarose is injected and this triggers local hypoxia, which then results in the differentiation of the periosteal MSCs into articular chondrocytes, i.e. cells similar to those found in the joint cartilage. Since this processes occurs in a relative short period of less than two weeks and cartilage can remodel into bone, this approach might provide some advantages in treatment of both cartilage and bone loss. The IVB concept needs to be however realized in humans and this is currently being undertaken. | 1 | Applied and Interdisciplinary Chemistry |
Zintl compounds feature naked anionic clusters that are generated by reduction of heavy main group p elements, mostly metals or semimetals, with alkali metals, often as a solution in anhydrous liquid ammonia or ethylenediamine. Examples of Zintl anions are [Bi], [Sn], [Pb], and [Sb]. Although these species are called "naked clusters," they are usually strongly associated with alkali metal cations. Some examples have been isolated using cryptate complexes of the alkali metal cation, e.g., [Pb] anion, which features a capped square antiprismatic shape. According to Wade's rules (2n+2) the number of cluster electrons is 22 and therefore a closo cluster. The compound is prepared from oxidation of KPb by Au in PPhAuCl (by reaction of tetrachloroauric acid and triphenylphosphine) in ethylene diamine with 2.2.2-crypt. This type of cluster was already known as is the endohedral Ni@Pb (the cage contains one nickel atom). The icosahedral tin cluster Sn or stannaspherene anion is another closed shell structure observed (but not isolated) with photoelectron spectroscopy. With an internal diameter of 6.1 Ångstrom, it is of comparable size to fullerene and should be capable of containing small atoms in the same manner as endohedral fullerenes, and indeed exists a Sn cluster that contains an Ir atom: [Ir@Sn]. | 0 | Theoretical and Fundamental Chemistry |
Although smart fluids are rightly seen as having many potential applications, they are limited in commercial feasibility for the following reasons:
* High density, due to presence of iron, makes them heavy. However, operating volumes are small, so while this is a problem, it is not insurmountable.
* High-quality fluids are expensive.
* Fluids are subject to thickening after prolonged use and need replacing.
* Settling of Ferro-particles can be a problem for some applications.
* Cannot operate at extremely High/Low temperatures
Commercial applications do exist, as mentioned, but will continue to be few until these problems (particularly cost) are overcome. | 1 | Applied and Interdisciplinary Chemistry |
Molds that are often found on meat and poultry include members of the genera Alternaria, Aspergillus, Botrytis, Cladosporium, Fusarium, Geotrichum, Mortierella, Mucor, Neurospora, Paecilomyces, Penicillium, and Rhizopus. Grain crops in particular incur considerable losses both in field and storage due to pathogens, post-harvest spoilage, and insect damage. A number of common microfungi are important agents of post-harvest spoilage, notably members of the genera Aspergillus, Fusarium, and Penicillium. A number of these produce mycotoxins (soluble, non-volatile toxins produced by a range of microfungi that demonstrate specific and potent toxic properties on human and animal cells) that can render foods unfit for consumption. When ingested, inhaled, or absorbed through skin, mycotoxins may cause or contribute to a range of effects from reduced appetite and general malaise to acute illness or death in rare cases. Mycotoxins may also contribute to cancer. Dietary exposure to the mycotoxin aflatoxin B1, commonly produced by growth of the fungus Aspergillus flavus on improperly stored ground nuts in many areas of the developing world, is known to independently (and synergistically with Hepatitis B virus) induce liver cancer. Mycotoxin-contaminated grain and other food products have a significant impact on human and animal health globally. According to the World Health Organization, roughly 25% of the world's food may be contaminated by mycotoxins.
Prevention of mold exposure from food is generally to consume food that has no mold growths on it. Also, mold growth in the first place can be prevented by the same concept of mold growth, assessment, and remediation that prevents air exposure. Also, it is especially useful to clean the inside of the refrigerator and to ensure dishcloths, towels, sponges, and mops are clean.
Ruminants are considered to have increased resistance to some mycotoxins, presumably due to the superior mycotoxin-degrading capabilities of their gut microbiota. The passage of mycotoxins through the food chain may also have important consequences on human health. For example, in China in December 2011, high levels of carcinogen aflatoxin M1 in Mengniu brand milk were found to be associated with the consumption of mold-contaminated feed by dairy cattle. | 1 | Applied and Interdisciplinary Chemistry |
Calcium deficiency can sometimes be rectified by adding agricultural lime to acid soils, aiming at a pH of 6.5, unless the subject plants specifically prefer acidic soil. Organic matter should be added to the soil to improve its moisture-retaining capacity. However, because of the nature of the disorder (i.e. poor transport of calcium to low transpiring tissues), the problem cannot generally be cured by the addition of calcium to the roots. In some species, the problem can be reduced by prophylactic spraying with calcium chloride of tissues at risk.
Plant damage is difficult to reverse, so corrective action should be taken immediately, supplemental applications of calcium nitrate at 200 ppm nitrogen, for example. Soil pH should be tested, and corrected if needed, because calcium deficiency is often associated with low pH.
Early fruit will generally have the worst symptoms, with them typically lessening as the season progresses. Preventative measures, such as irrigating prior to especially high temperatures and stable irrigation will minimize the occurrence. | 1 | Applied and Interdisciplinary Chemistry |
There are only three basic options for offgas treatment available. The volatilized contaminants in the offgas can either be discharged to atmosphere, collected or destroyed. In some cases, both a collection and destruction system are employed. In addition to managing the volatilized components, the particulate solids (dust) that exit the desorber must also be removed from the offgas.
When a collection system is used, the offgas must be cooled to condense the bulk of the volatilized components into a liquid. The offgas will exit most desorbers in the 350–900 °F range. The offgas is then typically cooled to somewhere between 120 and 40 °F to condense the bulk of the volatilized water and organic contaminants. Even at 40 °F, there may be measurable amounts of non-condensed organics. For this reason, after the condensation step, further treatment of the offgas is usually required. The cooled offgas may be treated by carbon adsorption, or thermal oxidation. Thermal oxidation can be accomplished using a catalytic oxidizer, an afterburner or by routing the offgas to the combustion heat source for the desorber. The volume of gas requiring treatment for indirect fired desorbers is a fraction of that required for a direct fired desorber. This requires smaller air pollution control trains for the gaseous process vent emissions. Some thermal desorption systems recycle the carrier gas, thereby further reducing the volume of gaseous emissions.
The condensed liquid from cooling the offgas is separated into organic and aqueous fractions. The water is either disposed of or used to cool the treated solids and prevent dusting. The condensed liquid organic is removed from the site. Depending on its composition, the liquid is either recycled as a supplemental fuel or destroyed in a fixed base incinerator. A thermal desorber removing 500 mg/kg of organic contaminants from 20,000 tons of soil will produce less than of liquid organic. In essence 20,000 tons of contaminated soil could be reduced to less than one tank truck of extracted liquid residue for off-site disposal.
Desorbers using offgas destruction systems use combustion to thermally destroy the volatilized organics components forming CO, CO, NOx, SOx and HCl. The destruction unit may be called an afterburner, secondary combustion chamber, or thermal oxidizer. Catalytic oxidizers may also be used if the organic halide content of the contaminated media is low enough. Regardless of the name, the destruction unit is used to thermally destroy the hazardous organic constituents that were removed (volatilized) from the soil or waste. | 1 | Applied and Interdisciplinary Chemistry |
Reduction of the anode by the photosynthetic material can be achieved by a direct electron transfer, or via a soluble redox mediator. Redox mediators may be lipid-soluble (e.g. vitamin K2), allowing them to pass through cell membranes, and can either be added to the system or produced by the biological material. | 0 | Theoretical and Fundamental Chemistry |
Diphenylamine is manufactured by the thermal deamination of aniline over oxide catalysts:
: 2 CHNH → (CH)NH + NH
It is a weak base, with a K of 10. With strong acids, it forms salts. For example, treatment with sulfuric acid gives the bisulfate [(CH)NH][HSO] as a white or yellowish powder with m.p. 123-125 °C.
Diphenylamine undergoes various cyclisation reactions. With sulfur, it gives phenothiazine, a precursor to pharmaceuticals.
: (CH)NH + 2 S → S(CH)NH + HS
With iodine, it undergoes dehydrogenation to give carbazole, with release of hydrogen iodide:
: (CH)NH + I → (CH)NH + 2 HI
Arylation with iodobenzene gives triphenylamine. it is also used as a test reagent in the dische's test . | 0 | Theoretical and Fundamental Chemistry |
* As with all carbonyl compounds, the protons on the α-carbon are labile due to keto–enol tautomerization. Thus, the α-carbon is easily halogenated in the Hell–Volhard–Zelinsky halogenation.
* The Schmidt reaction converts carboxylic acids to amines.
* Carboxylic acids are decarboxylated in the Hunsdiecker reaction.
* The Dakin–West reaction converts an amino acid to the corresponding amino ketone.
* In the Barbier–Wieland degradation, a carboxylic acid on an aliphatic chain having a simple methylene bridge at the alpha position can have the chain shortened by one carbon. The inverse procedure is the Arndt–Eistert synthesis, where an acid is converted into acyl halide, which is then reacted with diazomethane to give one additional methylene in the aliphatic chain.
* Many acids undergo oxidative decarboxylation. Enzymes that catalyze these reactions are known as carboxylases (EC 6.4.1) and decarboxylases (EC 4.1.1).
* Carboxylic acids are reduced to aldehydes via the ester and DIBAL, via the acid chloride in the Rosenmund reduction and via the thioester in the Fukuyama reduction.
* In ketonic decarboxylation carboxylic acids are converted to ketones.
* Organolithium reagents (>2 equiv) react with carboxylic acids to give a dilithium 1,1-diolate, a stable tetrahedral intermediate which decomposes to give a ketone upon acidic workup.
* The Kolbe electrolysis is an electrolytic, decarboxylative dimerization reaction. It gets rid of the carboxyl groups of two acid molecules, and joins the remaining fragments together. | 0 | Theoretical and Fundamental Chemistry |
Trimethylamine N-oxide reductase (TOR or TMAO reductase, EC 1.7.2.3) is a microbial enzyme that can reduce trimethylamine N-oxide (TMAO) into trimethylamine (TMA), as part of the electron transport chain. The enzyme has been purified from E. coli and the photosynthetic bacteria Roseobacter denitrificans.
Trimethylamine oxide is found at high concentrations in the tissues of fish, and the bacterial reduction of this compound to foul-smelling trimethylamine is a major process in the spoilage of fish. | 1 | Applied and Interdisciplinary Chemistry |
The uhp system is composed of UhpA, UhpB, UhpC, and UhpT. UhpB and UhpC are both transmembrane proteins which form a complex with each other. UhpA is a signal protein found in the cytoplasm. UhpT is a transporter protein which facilitates the uptake of phosphorylated hexose molecules into the cell. | 1 | Applied and Interdisciplinary Chemistry |
For at least 600 years, wood tar has been used as a water repellent coating for boats, ships, and roofs. In Scandinavia, it was produced as a cash crop. "Peasant Tar" might be named for the district of its production.
Wood tar is still used as an additive in the flavoring of candy, alcohol, and other foods. Wood tar is microbicidal. Producing tar from wood was known in ancient Greece and has probably been used in Scandinavia since the Iron Age. Production and trade in pine-derived tar was a major contributor in the economies of Northern Europe and Colonial America. Its main use was in preserving wooden sailing vessels against rot. For centuries, dating back at least to the 14th century, tar was among Sweden's most important exports. Sweden exported 13,000 barrels of tar in 1615 and 227,000 barrels in the peak year of 1863. The largest user was the Royal Navy of the United Kingdom. Demand for tar declined with the advent of iron and steel ships. Production nearly stopped in the early 20th century. Traditional wooden boats are still sometimes tarred.
The heating (dry distilling) of pine wood causes tar and pitch to drip away from the wood and leave behind charcoal. Birch bark is used to make particularly fine tar, known as "Russian oil", suitable for leather protection. The by-products of wood tar are turpentine and charcoal. When deciduous tree woods are subjected to destructive distillation, the products are methanol (wood alcohol) and charcoal.
Tar kilns (, , , ) are dry distillation ovens, historically used in Scandinavia for producing tar from wood. They were built close to the forest, from limestone or from more primitive holes in the ground. The bottom is sloped into an outlet hole to allow the tar to pour out. The wood is split into dimensions of a finger, stacked densely, and finally covered tight with earth and moss. If oxygen can enter, the wood might catch fire, and the production would be ruined. On top of this, a fire is stacked and lit. After a few hours, the tar starts to pour out and continues to do so for a few days. | 0 | Theoretical and Fundamental Chemistry |
Labeling studies establish the following regiochemistry:
:RCDO + CH=CHR → RC(O)CHCHDR
In terms of the reaction mechanism, hydroacylation begins with oxidative addition of the aldehydic carbon-hydrogen bond. The resulting acyl hydride complex next binds the alkene. The sequence of oxidative addition and alkene coordination is often unclear. Via migratory insertion, the alkene inserts into either the metal-acyl or the metal-hydride bonds. In the final step, the resulting alkyl-acyl or beta-ketoalkyl-hydride complex undergoes reductive elimination. A competing side-reaction is decarbonylation of the aldehyde. This process also proceeds via the intermediacy of the acyl metal hydride:
:R"C(O)-ML-H → R"-M(CO)L-H
This step can be followed by reductive elimination of the alkane:
:R"-M(CO)L-H → R"-H + M(CO)L | 0 | Theoretical and Fundamental Chemistry |
Adverse effects can include hypersensitivity reactions including urticaria, fever, joint pains, rashes, angioedema, anaphylaxis, serum sickness-like reaction. Rarely central nervous system toxicity including convulsions (especially with high doses or in severe renal impairment), interstitial nephritis, haemolytic anaemia, leucopenia, thrombocytopenia, and coagulation disorders. Also reported diarrhoea (including antibiotic-associated colitis). Benzylpenicillin has relatively low toxicity, except for in the nervous system, in which it is one of the most active drugs among β-lactam agents. In addition, benzylpenicillin is an irritant, a health hazard, and an environmental hazard.
Benzylpenicillin serum concentrations can be monitored either by traditional microbiological assay or by more modern chromatographic techniques. Such measurements can be useful to avoid central nervous system toxicity in any person receiving large doses of the drug on a chronic basis, but they are especially relevant to patients with kidney failure, who may accumulate the drug due to reduced urinary excretion rates. | 0 | Theoretical and Fundamental Chemistry |
The precursor mixture of powders and space-holders are compacted into a mold under a specified pressure. This can be achieved through uniaxial or isostatic processes. The pores resulting from this method are open and interconnected via windows between neighboring pores with the size of the pores partially dependent upon the coordination number and contact area of the resulting compact. Compaction pressure must be high enough to ensure sufficient mechanical strength for retention of pore geometry specified by the space-holder, but not too high enough as to cause deformation of the space-holder. | 0 | Theoretical and Fundamental Chemistry |
If the number of glass and batch components is not equal, if it is impossible to exactly obtain the desired glass composition using the selected batch ingredients, or if the matrix equation is not soluble for other reasons (i.e., the rows/columns are linearly dependent), the batch composition must be determined by optimization techniques. | 0 | Theoretical and Fundamental Chemistry |
In thermodynamics, a thermodynamic state of a system is its condition at a specific time; that is, fully identified by values of a suitable set of parameters known as state variables, state parameters or thermodynamic variables. Once such a set of values of thermodynamic variables has been specified for a system, the values of all thermodynamic properties of the system are uniquely determined. Usually, by default, a thermodynamic state is taken to be one of thermodynamic equilibrium. This means that the state is not merely the condition of the system at a specific time, but that the condition is the same, unchanging, over an indefinitely long duration of time. | 0 | Theoretical and Fundamental Chemistry |
Ion chromatography has advanced through the accumulation of knowledge over a course of many years. Starting from 1947, Spedding and Powell used displacement ion-exchange chromatography for the separation of the rare earths. Additionally, they showed the ion-exchange separation of 14N and 15N isotopes in ammonia. At the start of the 1950s, Kraus and Nelson demonstrated the use of many analytical methods for metal ions dependent on their separation of their chloride, fluoride, nitrate or sulfate complexes by anion chromatography. Automatic in-line detection was progressively introduced from 1960 to 1980 as well as novel chromatographic methods for metal ion separations. A groundbreaking method by Small, Stevens and Bauman at Dow Chemical Co. unfolded the creation of the modern ion chromatography. Anions and cations could now be separated efficiently by a system of suppressed conductivity detection. In 1979, a method for anion chromatography with non-suppressed conductivity detection was introduced by Gjerde et al. Following it in 1980, was a similar method for cation chromatography.
As a result, a period of extreme competition began within the IC market, with supporters for both suppressed and non-suppressed conductivity detection. This competition led to fast growth of new forms and the fast evolution of IC. A challenge that needs to be overcome in the future development of IC is the preparation of highly efficient monolithic ion-exchange columns and overcoming this challenge would be of great importance to the development of IC.
The boom of Ion exchange chromatography primarily began between 1935 and 1950 during World War II and it was through the "Manhattan project" that applications and IC were significantly extended. Ion chromatography was originally introduced by two English researchers, agricultural Sir Thompson and chemist J T Way. The works of Thompson and Way involved the action of water-soluble fertilizer salts, ammonium sulfate and potassium chloride. These salts could not easily be extracted from the ground due to the rain. They performed ion methods to treat clays with the salts, resulting in the extraction of ammonia in addition to the release of calcium. It was in the fifties and sixties that theoretical models were developed for IC for further understanding and it was not until the seventies that continuous detectors were utilized, paving the path for the development from low-pressure to high-performance chromatography. Not until 1975 was "ion chromatography" established as a name in reference to the techniques, and was thereafter used as a name for marketing purposes. Today IC is important for investigating aqueous systems, such as drinking water. It is a popular method for analyzing anionic elements or complexes that help solve environmentally relevant problems. Likewise, it also has great uses in the semiconductor industry.
Because of the abundant separating columns, elution systems, and detectors available, chromatography has developed into the main method for ion analysis.
When this technique was initially developed, it was primarily used for water treatment. Since 1935, ion exchange chromatography rapidly manifested into one of the most heavily leveraged techniques, with its principles often being applied to majority of fields of chemistry, including distillation, adsorption, and filtration. | 0 | Theoretical and Fundamental Chemistry |
SHINGRIX is a licensed recombinant subunit vaccine for protection against Herpes Zoster, whose risk of developing increases with decline of varicella zoster virus (VZV) specific immunity. The vaccine contains VZV gE antigen component extracted from CHO cells, which is to be reconstituted with adjuvant suspension AS01.
Systematic reviews and meta-analyses have been conducted on the efficacy, effectiveness and safety of SHINGRIX in immunocompromised 18-49 year old patients and healthy adults aged 50 and over. These studies reported humoral and cell-mediated immunity rate ranged between 65.4 and 96.2% and 50.0%-93.0% while efficacy in patients (18-49 yo) with haematological malignancies was estimated at 87.2% (95%CI, 44.3–98.6%) up to 13 months post-vaccination with an acceptable safety profile. | 1 | Applied and Interdisciplinary Chemistry |
*Berkeley Catalysis Center
*Berkeley Center for Green Chemistry
*Berkeley Global Science Institute
*Berkeley Nanosciences and Nanoengineering Institute
*Berkeley Nanotechnology Club
*Berkeley Quantum Information and Computation Center
*Berkeley Stem Cell Center
*California Research Alliance
*CalSolv Center
*Center for Computational Biology
*Center for Genetically Coded Materials
*Center for Information Technology Research in the Interest of Society (CITRIS)
*California Institute for Quantitative Biosciences (QB3)
*Energy Biosciences Institute (EBI)
*Energy Frontier Research Center on Gas Separations
*Joint BioEnergy Institute
*Joint Center for Artificial Photosynthesis
*Pitzer Center for Theoretical Chemistry
*Synthetic Biology Engineering Research Center | 1 | Applied and Interdisciplinary Chemistry |
A radiocarbon dating study in 2018 found that after the 30-meter isobath, only around 10% of the methane in surface waters can be attributed to ancient permafrost or methane hydrates. The authors suggested that even a significantly accelerated methane release would still largely fail to reach the atmosphere. | 0 | Theoretical and Fundamental Chemistry |
Ponceau S, Acid Red 112, or C.I. 27195 (systematic name: 3-hydroxy-4-(2-sulfo-4-[4-sulfophenylazo]phenylazo)-2,7-naphthalenedisulfonic acid sodium salt) is a sodium salt of a diazo dye of a light red color, that may be used to prepare a stain for rapid reversible detection of protein bands on nitrocellulose or polyvinylidene fluoride (PVDF) membranes (western blotting), as well as on cellulose acetate membranes. A Ponceau S stain is useful because it does not appear to have a deleterious effect on the sequencing of blotted polypeptides and is therefore one method of choice for locating polypeptides on western blots for blot-sequencing. It is also easily reversed with water washes, facilitating subsequent immunological detection. The stain can be completely removed from the protein bands by continued washing. Common stain formulations include 0.1% (w/v) Ponceau S in 5% acetic acid or 2% (w/v) Ponceau S in 30% trichloroacetic acid and 30% sulfosalicylic acid. | 0 | Theoretical and Fundamental Chemistry |
As a Department of Energy Committee writing on the human radiation experiments wrote, "It appears to have been almost immediately apparent to the AEC and the Joint Task Force running the Castle series that research on radiation effects could be done in conjunction with the medical treatment of the exposed populations." The DOE report also concluded that "The dual purpose of what is now a DOE medical program has led to a view by the Marshallese that they were being used as guinea pigs in a radiation experiment."
Organizations involved in the project included the Naval Medical Research Institute, the Naval Radiological Defense Laboratory, Patrol Squadron 29, the Naval Air Station, Kwajalein, Los Alamos National Laboratory, the Applied Fisheries Laboratory at the University of Washington, and Hanford Atomic Power Operations. Three U.S. Navy ships were used in the project: USS Nicholas, USS Renshaw, and USS Philip. The primary study of the Marshallese was terminated around 75 days after the time of exposure. In July 1954 a meeting at the Division of Biology at the U.S. Atomic Energy Commission decided to complete 6- and 12-month follow-up exposure studies, some of which were later written up as addendums to Project 4.1. | 0 | Theoretical and Fundamental Chemistry |
After several years of cooling, most radioactivity is from the fission products caesium-137 and strontium-90, which are each produced in about 6% of fissions, and have half-lives of about 30 years. Other fission products with similar half-lives have much lower fission product yields, lower decay energy, and several (Sm, Eu, Cd) are also quickly destroyed by neutron capture while still in the reactor, so are not responsible for more than a tiny fraction of the radiation production at any time. Therefore, in the period from several years to several hundred years after use, radioactivity of spent fuel can be modeled simply as exponential decay of the Cs and Sr. These are sometimes known as medium-lived fission products.
Krypton-85, the 3rd most active MLFP, is a noble gas which is allowed to escape during current nuclear reprocessing; however, its inertness means that it does not concentrate in the environment, but diffuses to a uniform low concentration in the atmosphere. Spent fuel in the U.S. and some other countries is not likely to be reprocessed until decades after use, and by that time most of the Kr will have decayed. | 0 | Theoretical and Fundamental Chemistry |
The first type of molecular marker developed and run on gel electrophoresis were allozymes. These markers are used for the detection of protein variation. The word "allozyme" (also known as "alloenzyme") comes from "allelic variants of enzymes." When run on a gel, proteins are separated by size and charge. Although allozymes may seem dated when compared to the other markers available, they are still used today, mainly due to their low cost. One major downside is that since there is only a limited amount available, specificity an issue. | 1 | Applied and Interdisciplinary Chemistry |
The process in which amylase breaks down starch for sugar consumption is not consistent with all organisms that use amylase to breakdown stored starch. There are different amylase pathways that are involved in starch degradation. The occurrence of starch degradation into sugar by the enzyme amylase was most commonly known to take place in the Chloroplast, but that has been proven wrong. One example is the spinach plant, in which the chloroplast contains both alpha and beta amylase (They are different versions of amylase involved in the breakdown of starch and they differ in their substrate specificity). In spinach leaves, the extrachloroplastic region contains the highest level of amylase degradation of starch. The difference between chloroplast and extrachloroplastic starch degradation is in the amylase pathway they prefer; either beta or alpha amylase. For spinach leaves, Alpha-amylase is preferred but for plants/organisms like wheat, barley, peas, etc. the Beta-amylase is preferred. | 0 | Theoretical and Fundamental Chemistry |
It is legal under EU law to sell and buy seeds from a composite cross population as an experiment in the period between 2014 and 2018. | 1 | Applied and Interdisciplinary Chemistry |
Nervous system control over hormone release is based in the hypothalamus, from which the neurons that populate the pariventricular and arcuate nuclei originate. These neurons project to the median eminence, where they secrete releasing hormones into the hypophysial portal system connecting the hypothalamus with the pituitary gland. There, they dictate endocrine function via the four Hypothalamic-Pituitary-Glandular axes. Recent studies have begun to offer evidence that many pituitary hormones which have been observed to be released episodically are preceded by pulsatile secretion of their associated releasing hormone from the hypothalamus in a similar pulsatile fashion. Novel research into the cellular mechanisms associated with pituitary hormone pulsatility, such as that observed for Leutinizing Hormone (LH) and Follicle Stimulating Hormone (FSH), have indicated similar pulses into the hypophyseal vessels of Gonadotropin Releasing Hormone (GnRH). | 1 | Applied and Interdisciplinary Chemistry |
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