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For cast iron the equivalent carbon content (CE) concept is used to understand how alloying elements will affect the heat treatment and casting behavior. It is used as a predictor of strength in cast irons because it gives an approximate balance of austenite and graphite in final structure. A number of formulas are available to determine the CE in cast irons, where an increasing number of elements are included:
This CE is then used to determine if the alloy is hypoeutectic, eutectic, or hypereutectic; for cast irons the eutectic is 4.3% carbon. When casting cast iron this is useful for determining the final grain structure; for example, a hypereutectic cast iron usually has a coarse grain structure and large kish graphite flakes are formed. Also, there is less shrinkage as the CE increases. When heat treating cast iron, various CE samples are tested to empirically determine the correlation between CE and hardness. The following is an example for induction hardened gray irons: | 0 | Metallurgy |
Calmodulin plays an important role in excitation contraction (EC) coupling and the initiation of the cross-bridge cycling in smooth muscle, ultimately causing smooth muscle contraction. In order to activate contraction of smooth muscle, the head of the myosin light chain must be phosphorylated. This phosphorylation is done by myosin light chain (MLC) kinase. This MLC kinase is activated by a calmodulin when it is bound by calcium, thus making smooth muscle contraction dependent on the presence of calcium, through the binding of calmodulin and activation of MLC kinase.
Another way that calmodulin affects muscle contraction is by controlling the movement of Ca across both the cell and sarcoplasmic reticulum membranes. The Ca channels, such as the ryanodine receptor of the sarcoplasmic reticulum, can be inhibited by calmodulin bound to calcium, thus affecting the overall levels of calcium in the cell. Calcium pumps take calcium out of the cytoplasm or store it in the endoplasmic reticulum and this control helps regulate many downstream processes.
This is a very important function of calmodulin because it indirectly plays a role in every physiological process that is affected by smooth muscle contraction such as digestion and contraction of arteries (which helps distribute blood and regulate blood pressure). | 1 | Gene expression + Signal Transduction |
The amount of calcium in blood (more specifically, in blood plasma) can be measured as total calcium, which includes both protein-bound and free calcium. In contrast, ionized calcium is a measure of free calcium. An abnormally high level of calcium in plasma is termed hypercalcemia and an abnormally low level is termed hypocalcemia, with "abnormal" generally referring to levels outside the reference range.
The main methods to measure serum calcium are:
* O-Cresolphalein Complexone Method; A disadvantage of this method is that the volatile nature of the 2-amino-2-methyl-1-propanol used in this method makes it necessary to calibrate the method every few hours in a clinical laboratory setup.
* Arsenazo III Method; This method is more robust, but the arsenic in the reagent is a health hazard.
The total amount of Ca present in a tissue may be measured using Atomic absorption spectroscopy, in which the tissue is vaporized and combusted. To measure Ca concentration or spatial distribution within the cell cytoplasm in vivo or in vitro, a range of fluorescent reporters may be used. These include cell permeable, calcium-binding fluorescent dyes such as Fura-2 or genetically engineered variant of green fluorescent protein (GFP) named Cameleon. | 1 | Gene expression + Signal Transduction |
During a hydroelectric plant project, in the southern foothills of the Central Highlands, Samanalawewa, in Sri Lanka, a wind-driven furnace was found in an excavation site. Such furnaces were powered by the monsoon winds and have been dated to 300 BC using radiocarbon-dating techniques. These ancient Lankan furnaces might have produced the best-quality steel for legendary Damascus swords as referred in earlier Syrian records. Field trials using replica furnaces confirmed that this furnace type uses a wind-based air-supply principle that is distinct from either forced or natural draught, and show also that they are capable of producing high-carbon steel.
Wrought iron was used in the construction of monuments such as the iron pillar of Delhi, built in the third century AD during the Gupta Empire. The latter was built using a towering series of disc-shaped iron blooms. Similar to China, high-carbon steel was eventually used in India, although cast iron was not used for architecture until modern times. | 0 | Metallurgy |
Adding elements is usually helpful because of solid solution strengthening, but can result in unwanted precipitation. Precipitates can be classified as geometrically close-packed (GCP), topologically close-packed (TCP), or carbides. GCP phases usually benefit mechanical properties, but TCP phases are often deleterious. Because TCP phases are not truly close packed, they have few slip systems and are brittle. Also they "scavenge" elements from GCP phases. Many elements that are good for forming γ' or have great solid solution strengthening may precipitate TCPs. The proper balance promotes GCPs while avoiding TCPs.
TCP phase formation areas are weak because they:
* have inherently poor mechanical properties
* are incoherent with the γ matrix
* are surrounded by a "depletion zone" where there is no γ'
* usually form sharp plate or needle-like morphologies which nucleate cracks
The main GCP phase is γ. Almost all superalloys are Ni-based because of this phase. γ is an ordered L1 (pronounced L-one-two), which means it has a certain atom on the face of the unit cell, and a certain atom on the corners of the unit cell. Ni-based superalloys usually present Ni on the faces and Ti or Al on the corners.
Another "good" GCP phase is γ. It is also coherent with γ, but it dissolves at high temperatures. | 0 | Metallurgy |
* Nematoda: Ascaris, Caenorhabditis ;
* Mollusca: Bivalvia); Polyplacophora;
* Arthropoda/Crustacea: Artemia;
* Arthropoda/Insecta: Drosophila [<nowiki />Locusta migratoria (migratory locust), Apis mellifera (honeybee)]. | 1 | Gene expression + Signal Transduction |
In many binary semiconducting systems, the band gap in semiconductors is approximately a linear function of the lattice parameter. Therefore, if the lattice parameter of a semiconducting system follows Vegard's law, one can also write a linear relationship between the band gap and composition. Using as before, the band gap energy, , can be written as:
Sometimes, the linear interpolation between the band gap energies is not accurate enough, and a second term to account for the curvature of the band gap energies as a function of composition is added. This curvature correction is characterized by the bowing parameter, : | 0 | Metallurgy |
Coactivators are promising targets for drug therapies in the treatment of cancer, metabolic disorder, cardiovascular disease and type 2 diabetes, along with many other disorders. For example, the steroid receptor coactivator (SCR) NCOA3 is often overexpressed in breast cancer, so the development of an inhibitor molecule that targets this coactivator and decreases its expression could be used as a potential treatment for breast cancer.
Because transcription factors control many different biological processes, they are ideal targets for drug therapy. The coactivators that regulate them can be easily replaced with a synthetic ligand that allows for control over an increase or decrease in gene expression.
Further technological advances will provide new insights into the function and regulation of coactivators at a whole-organism level and elucidate their role in human disease, which will hopefully provide better targets for future drug therapies. | 1 | Gene expression + Signal Transduction |
Transcription factories, in genetics describe the discrete sites where transcription occurs in the cell nucleus, and are an example of a biomolecular condensate. They were first discovered in 1993 and have been found to have structures analogous to replication factories, sites where replication also occurs in discrete sites. The factories contain an RNA polymerase (active or inactive) and the necessary transcription factors (activators and repressors) for transcription. Transcription factories containing RNA polymerase II are the most studied but factories can exist for RNA polymerase I and III; the nucleolus being seen as the prototype for transcription factories. It is possible to view them under both light and electron microscopy. The discovery of transcription factories has challenged the original view of how RNA polymerase interacts with the DNA polymer and it is thought that the presence of factories has important effects on gene regulation and nuclear structure. | 1 | Gene expression + Signal Transduction |
These elements are bound by specific uncharged tRNAs and modulate the expression of corresponding aminoacyl-tRNA synthetase operons. High levels of uncharged tRNA promote the anti-terminator sequence leading to increased concentrations of charged tRNA. These are considered by some to be a separate family of riboswitches but are significantly more complex than the previous class of attenuators. | 1 | Gene expression + Signal Transduction |
Three-letter abbreviations are used to describe phenotypes in bacteria including E. coli.
Examples include:
* Lac (the ability to use lactose),
* His (the ability to synthesize the amino acid histidine)
* Mot (swimming motility)
* Sm (resistance to the antibiotic streptomycin)
In the case of Lac, wild type cells are Lac and are able to use lactose as a carbon and energy source, while Lac mutant derivatives cannot use lactose. The same three letters are typically used (lower-case, italicized) to label the genes involved in a particular phenotype, where each different gene is additionally distinguished by an extra letter. The lac genes encoding enzymes are lacZ, lacY, and lacA. The fourth lac gene is lacI, encoding the lactose repressor—"I" stands for inducibility.
One may distinguish between structural genes encoding enzymes, and regulatory genes encoding proteins that affect gene expression. Current usage expands the phenotypic nomenclature to apply to proteins: thus, LacZ is the protein product of the lacZ gene, β-galactosidase. Various short sequences that are not genes also affect gene expression, including the lac promoter, lac p, and the lac operator, lac o. Although it is not strictly standard usage, mutations affecting lac o are referred to as lac o, for historical reasons. | 1 | Gene expression + Signal Transduction |
It is known that ribosomes pause at distinct sites, but the reasons for these pauses are mostly unknown. Also, the ribosome pauses if the pseudoknot is disrupted. 10% of the ribosome pauses at the pseudoknot and 4% of the ribosomes are terminated. Before the ribosome is obstructed it passes the pseudoknot. An assay was put together by a group from the University of California in an effort to show a model of mRNA. The translation was monitored in two in vitro systems. It was found that translating ribosomes arent uniformly distributed along an mRNA. Protein folding in vivo is also important and is related to protein synthesis. For finding the location of the ribosomal pause in vivo, the methods that have been used to find the ribosomal pause in vitro can be changed to find these specific locations in vivo.' | 1 | Gene expression + Signal Transduction |
Single-crystal superalloys (SX or SC superalloys) are formed as a single crystal using a modified version of the directional solidification technique, leaving no grain boundaries. The mechanical properties of most other alloys depend on the presence of grain boundaries, but at high temperatures, they participate in creep and require other mechanisms. In many such alloys, islands of an ordered intermetallic phase sit in a matrix of disordered phase, all with the same crystal lattice. This approximates the dislocation-pinning behavior of grain boundaries, without introducing any amorphous solid into the structure.
Single crystal (SX) superalloys have wide application in the high-pressure turbine section of aero- and industrial gas turbine engines due to the unique combination of properties and performance. Since introduction of single crystal casting technology, SX alloy development has focused on increased temperature capability, and major improvements in alloy performance are associated with rhenium (Re) and ruthenium (Ru).
The creep deformation behavior of superalloy single crystal is strongly temperature-, stress-, orientation- and alloy-dependent. For a single-crystal superalloy, three modes of creep deformation occur under regimes of different temperature and stress: rafting, tertiary, and primary. At low temperature (~750 °C), SX alloys exhibits mostly primary creep behavior. Matan et al. concluded that the extent of primary creep deformation depends strongly on the angle between the tensile axis and the <001>/<011> symmetry boundary. At temperatures above 850 °C, tertiary creep dominates and promotes strain softening behavior. When temperature exceeds 1000 °C, the rafting effect is prevalent where cubic particles transform into flat shapes under tensile stress. The rafts form perpendicular to the tensile axis, since γ phase is transported out of the vertical channels and into the horizontal ones. Reed et al. studied unaxial creep deformation of <001> oriented CMSX-4 single crystal superalloy at 1105 °C and 100 MPa. They reported that rafting is beneficial to creep life since it delays evolution of creep strain. In addition, rafting occurs quickly and suppresses the accumulation of creep strain until a critical strain is reached. | 0 | Metallurgy |
The process of space corrosion is being actively investigated. One of the efforts aims to design a sensor based on zinc oxide, able to measure the amount of atomic oxygen in the vicinity of the spacecraft; the sensor relies on drop of electrical conductivity of zinc oxide as it absorbs further oxygen. | 0 | Metallurgy |
hnRNPs also play a role in DNA damage response in coordination with p53. hnRNP K is rapidly induced after DNA damage by ionizing radiation. It cooperates with p53 to induce the activation of p53 target genes, thus activating cell-cycle checkpoints. p53 itself is an important tumor-suppressor gene sometimes known by the epithet “the guardian of the genome.” hnRNP K’s close association with p53 demonstrates its importance in DNA damage control.
p53 regulates a large group of RNAs that are not translated into protein, called large intergenic noncoding RNAs (lincRNAs). p53 suppression of genes is often carried out by a number of these lincRNAs, which in turn have been shown to act though hnRNP K. Through physical interactions with these molecules, hnRNP K is targeted to genes and transmits p53 regulation, thus acting as a key repressor within the p53-dependent transcriptional pathway. | 1 | Gene expression + Signal Transduction |
Epigenetic instability caused by deregulation in chromatin remodeling is studied in several cancers, including breast cancer, colorectal cancer, pancreatic cancer. Such instability largely cause widespread silencing of genes with primary impact on tumor-suppressor genes. Hence, strategies are now being tried to overcome epigenetic silencing with synergistic combination of HDAC inhibitors or HDI and DNA-demethylating agents.
HDIs are primarily used as adjunct therapy in several cancer types. HDAC inhibitors can induce p21 (WAF1) expression, a regulator of p53's tumor suppressoractivity. HDACs are involved in the pathway by which the retinoblastoma protein (pRb) suppresses cell proliferation. Estrogen is well-established as a mitogenic factor implicated in the tumorigenesis and progression of breast cancer via its binding to the estrogen receptor alpha (ERα). Recent data indicate that chromatin inactivation mediated by HDAC and DNA methylation is a critical component of ERα silencing in human breast cancer cells.
* Approved usage:
**Vorinostat was licensed by the U.S. FDA in October 2006 for the treatment of cutaneous T cell lymphoma (CTCL).
**Romidepsin (trade name Istodax) was licensed by the US FDA in Nov 2009 for cutaneous T-cell lymphoma (CTCL).
* Phase III Clinical trials:
** Panobinostat (LBH589) is in clinical trials for various cancers including a phase III trial for cutaneous T cell lymphoma (CTCL).
** Valproic acid (as Mg valproate) in phase III trials for cervical cancer and ovarian cancer.
* Started pivotal phase II clinical trials:
** Belinostat (PXD101) has had a phase II trial for relapsed ovarian cancer, and reported good results for T cell lymphoma.
** HDAC inhibitors.
Current front-runner candidates for new drug targets are Histone Lysine Methyltransferases (KMT) and Protein Arginine Methyltransferases (PRMT). | 1 | Gene expression + Signal Transduction |
Myogenin, is a transcriptional activator encoded by the MYOG gene.
Myogenin is a muscle-specific basic-helix-loop-helix (bHLH) transcription factor involved in the coordination of skeletal muscle development or myogenesis and repair. Myogenin is a member of the MyoD family of transcription factors, which also includes MyoD, Myf5, and MRF4.
In mice, myogenin is essential for the development of functional skeletal muscle. Myogenin is required for the proper differentiation of most myogenic precursor cells during the process of myogenesis. When the DNA coding for myogenin was knocked out of the mouse genome, severe skeletal muscle defects were observed. Mice lacking both copies of myogenin (homozygous-null) suffer from perinatal lethality due to the lack of mature secondary skeletal muscle fibers throughout the body.
In cell culture, myogenin can induce myogenesis in a variety of non-muscle cell types. | 1 | Gene expression + Signal Transduction |
High temperature hydrogen attack (HTHA), also called hot hydrogen attack or methane reaction, is a problem which concerns steels operating at elevated temperatures (typically above ) in hydrogen-rich atmospheres, such as refineries, petrochemical and other chemical facilities and, possibly, high pressure steam boilers. It is not to be confused with hydrogen embrittlement.
If a steel is exposed to very hot hydrogen, the high temperature enables the hydrogen molecules to dissociate and to diffuse into the alloy as individual diffusible atoms. There are two stages to the damage:
# First, dissolved carbon in the steel reacts with the surface hydrogen and escapes into the gas as methane. This leads to superficial decarburization and a loss of strength in the surface. Initially, the damage is not visible.
# Second, the reduction in the concentration of dissolved carbon creates a driving force which dissolves the carbides in the steel. This leads to a loss of strength deeper in the steel and is more serious. At the same time, some hydrogen atoms diffuse into the steel and combine with carbon to form tiny pockets of methane at internal surfaces, such as grain boundaries and defects. This methane gas cannot diffuse out of the metal, and collects in the voids at high pressure and initiates cracks in the steel. This selective leaching of carbon is a more serious loss of strength and ductility.
HTHA can be managed by using a different steel alloy, one where the carbides with other alloying elements, such as chromium and molybdenum, are more stable than iron carbides. Surface oxide layers are ineffective as a protection as they are immediately reduced by the hydrogen, forming water vapour.
Later-stage damage in the steel component can be seen using ultrasonic examination, which detects the large defects created by methane pressure. These large defects in a stressed component are usually the cause of failure in service: which is usually catastrophic as hot flammable hydrogen gas escapes rapidly. | 0 | Metallurgy |
The initial product of copper smelting was impure black copper, which was then repeatedly melted to purify it, alternately oxidizing and reducing it. In one of the melting stages, lead was added. Gold and silver preferentially dissolved in this, thus providing a means of recovering these precious metals. To produce purer copper suitable for making copper plates or hollow-ware, further melting processes were undertaken, using charcoal as fuel. The repeated application of such fire-refining processes was capable of producing copper that was 99.25% pure. | 0 | Metallurgy |
Archaea have a single type of RNAP, responsible for the synthesis of all RNA. Archaeal RNAP is structurally and mechanistically similar to bacterial RNAP and eukaryotic nuclear RNAP I-V, and is especially closely structurally and mechanistically related to eukaryotic nuclear RNAP II.
The history of the discovery of the archaeal RNA polymerase is quite recent. The first analysis of the RNAP of an archaeon was performed in 1971, when the RNAP from the extreme halophile Halobacterium cutirubrum was isolated and purified. Crystal structures of RNAPs from Sulfolobus solfataricus and Sulfolobus shibatae set the total number of identified archaeal subunits at thirteen.
Archaea has the subunit corresponding to Eukaryotic Rpb1 split into two. There is no homolog to eukaryotic Rpb9 (POLR2I) in the S. shibatae complex, although TFS (TFIIS homolog) has been proposed as one based on similarity. There is an additional subunit dubbed Rpo13; together with Rpo5 it occupies a space filled by an insertion found in bacterial β′ subunits (1,377–1,420 in Taq). An earlier, lower-resolution study on S. solfataricus structure did not find Rpo13 and only assigned the space to Rpo5/Rpb5. Rpo3 is notable in that it's an iron–sulfur protein. RNAP I/III subunit AC40 found in some eukaryotes share similar sequences, but does not bind iron. This domain, in either case, serves a structural function.
Archaeal RNAP subunit previously used an "RpoX" nomenclature where each subunit is assigned a letter in a way unrelated to any other systems. In 2009, a new nomenclature based on Eukaryotic Pol II subunit "Rpb" numbering was proposed. | 1 | Gene expression + Signal Transduction |
Sodium dithionite finds widespread use in industry as a reducing agent. It is for example used in bleaching of pulp and some dyes. | 0 | Metallurgy |
So far only about two dozen sites have been identified where iron was made before the Roman invasion, mostly scattered across East Sussex and the Vale of Kent. A large site at Broadfield, Crawley is the westernmost place where smelting has been ascertained, although there is a possible site associated with an Iron Age enclosure at Piper's Copse near Northchapel in the western Weald. Continuity of pottery styles from the Iron Age into the early Roman period makes precise dating of many sites to before or after the Roman conquest difficult. Carbon dating has identified a site at Cullinghurst Wood, Hartfield to between 350 and 750 BC.
During his invasions of Britain in 55 and 54 BC Julius Caesar noted iron production near the coast, possibly at known sites at Sedlescombe and Crowhurst Park near Hastings. | 0 | Metallurgy |
Rokushō is used to treat a number of metals, including raw natural copper, which holds impurities, purified copper, and copper alloy mixes with two to five metals, to produce irogane metals, including: shakudō, an alloy of copper and gold, which becomes black to dark blue-violet; shibuichi, an alloy of fine silver and copper (in a higher percentage than sterling), which turns grey to misty aquamarine or other shades of blue to green; kuromido which becomes dark coppery black.
Rokushō was generally used to patinate all types of mokume-gane ("wood grain metal") as well.
Although other patination agents can be used on these metals, some artisans prefer the rich colors achieved with traditional rokushō in the niiro process.
These metals are becoming increasingly popular in high-end artistic jewelry, especially in bi-metals (a layer of the alloy fused to another metal such as sterling). Because rokushō has a dramatically different effect on sterling silver than on the alloys typically fused to it in bi-metals, a common technique in art jewelry is to engrave through the alloy layer in a pattern to reveal the silver underneath prior to patination. This provides a rich contrast in color, highlighting the pattern. | 0 | Metallurgy |
Properties of materials such as electrical conduction and heat capacity are investigated by solid state physics. An early model of electrical conduction was the Drude model, which applied kinetic theory to the electrons in a solid. By assuming that the material contains immobile positive ions and an "electron gas" of classical, non-interacting electrons, the Drude model was able to explain electrical and thermal conductivity and the Hall effect in metals, although it greatly overestimated the electronic heat capacity.
Arnold Sommerfeld combined the classical Drude model with quantum mechanics in the free electron model (or Drude-Sommerfeld model). Here, the electrons are modelled as a Fermi gas, a gas of particles which obey the quantum mechanical Fermi–Dirac statistics. The free electron model gave improved predictions for the heat capacity of metals, however, it was unable to explain the existence of insulators.
The nearly free electron model is a modification of the free electron model which includes a weak periodic perturbation meant to model the interaction between the conduction electrons and the ions in a crystalline solid. By introducing the idea of electronic bands, the theory explains the existence of conductors, semiconductors and insulators.
The nearly free electron model rewrites the Schrödinger equation for the case of a periodic potential. The solutions in this case are known as Bloch states. Since Blochs theorem applies only to periodic potentials, and since unceasing random movements of atoms in a crystal disrupt periodicity, this use of Blochs theorem is only an approximation, but it has proven to be a tremendously valuable approximation, without which most solid-state physics analysis would be intractable. Deviations from periodicity are treated by quantum mechanical perturbation theory. | 0 | Metallurgy |
# The effector of both the G and G pathways is the cyclic-adenosine monophosphate (cAMP)-generating enzyme adenylate cyclase, or AC. While there are ten different AC gene products in mammals, each with subtle differences in tissue distribution or function, all catalyze the conversion of cytosolic adenosine triphosphate (ATP) to cAMP, and all are directly stimulated by G-proteins of the G class. In contrast, however, interaction with Gα subunits of the G type inhibits AC from generating cAMP. Thus, a GPCR coupled to G counteracts the actions of a GPCR coupled to G, and vice versa. The level of cytosolic cAMP may then determine the activity of various ion channels as well as members of the ser/thr-specific protein kinase A (PKA) family. Thus cAMP is considered a second messenger and PKA a secondary effector.
# The effector of the G pathway is phospholipase C-β (PLCβ), which catalyzes the cleavage of membrane-bound phosphatidylinositol 4,5-bisphosphate (PIP2) into the second messengers inositol (1,4,5) trisphosphate (IP3) and diacylglycerol (DAG). IP3 acts on IP3 receptors found in the membrane of the endoplasmic reticulum (ER) to elicit Ca release from the ER, while DAG diffuses along the plasma membrane where it may activate any membrane localized forms of a second ser/thr kinase called protein kinase C (PKC). Since many isoforms of PKC are also activated by increases in intracellular Ca, both these pathways can also converge on each other to signal through the same secondary effector. Elevated intracellular Ca also binds and allosterically activates proteins called calmodulins, which in turn tosolic small GTPase, Rho. Once bound to GTP, Rho can then go on to activate various proteins responsible for cytoskeleton regulation such as Rho-kinase (ROCK). Most GPCRs that couple to G also couple to other sub-classes, often G. | 1 | Gene expression + Signal Transduction |
LaNi is an intermetallic compound with a CaCu structure. It belongs to the hexagonal crystal system. It can be oxidized by air above 200 °C, and react with hydrochloric acid, sulfuric acid or nitric acid above 20 °C. LaNi can be used as a catalyst for hydrogenation reactions. | 0 | Metallurgy |
The karat (US spelling, symbol k or Kt) or carat (UK spelling, symbol c or Ct) is a fractional measure of purity for gold alloys, in parts fine per 24 parts whole. The karat system is a standard adopted by US federal law. | 0 | Metallurgy |
Morpholinos are synthetic molecules that are the product of a redesign of natural nucleic acid structure. Usually 25 bases in length, they bind to complementary sequences of RNA or single-stranded DNA by standard nucleic acid base-pairing. In terms of structure, the difference between Morpholinos and DNA is that, while Morpholinos have standard nucleic acid bases, those bases are bound to methylenemorpholine rings linked through phosphorodiamidate groups instead of phosphates. The figure compares the structures of the two strands depicted there, one of RNA and the other of a Morpholino. Replacement of anionic phosphates with the uncharged phosphorodiamidate groups eliminates ionization in the usual physiological pH range, so Morpholinos in organisms or cells are uncharged molecules. The entire backbone of a Morpholino is made from these modified subunits. | 1 | Gene expression + Signal Transduction |
The physical properties of solids have been common subjects of scientific inquiry for centuries, but a separate field going by the name of solid-state physics did not emerge until the 1940s, in particular with the establishment of the Division of Solid State Physics (DSSP) within the American Physical Society. The DSSP catered to industrial physicists, and solid-state physics became associated with the technological applications made possible by research on solids. By the early 1960s, the DSSP was the largest division of the American Physical Society.
Large communities of solid state physicists also emerged in Europe after World War II, in particular in England, Germany, and the Soviet Union. In the United States and Europe, solid state became a prominent field through its investigations into semiconductors, superconductivity, nuclear magnetic resonance, and diverse other phenomena. During the early Cold War, research in solid state physics was often not restricted to solids, which led some physicists in the 1970s and 1980s to found the field of condensed matter physics, which organized around common techniques used to investigate solids, liquids, plasmas, and other complex matter. Today, solid-state physics is broadly considered to be the subfield of condensed matter physics, often referred to as hard condensed matter, that focuses on the properties of solids with regular crystal lattices. | 0 | Metallurgy |
An electrical synapse is an electrically conductive link between two abutting neurons that is formed at a narrow gap between the pre- and postsynaptic cells, known as a gap junction. At gap junctions, cells approach within about 3.5 nm of each other, rather than the 20 to 40 nm distance that separates cells at chemical synapses. As opposed to chemical synapses, the postsynaptic potential in electrical synapses is not caused by the opening of ion channels by chemical transmitters, but rather by direct electrical coupling between both neurons. Electrical synapses are faster than chemical synapses. Electrical synapses are found throughout the nervous system, including in the retina, the reticular nucleus of the thalamus, the neocortex, and in the hippocampus. While chemical synapses are found between both excitatory and inhibitory neurons, electrical synapses are most commonly found between smaller local inhibitory neurons. Electrical synapses can exist between two axons, two dendrites, or between an axon and a dendrite. In some fish and amphibians, electrical synapses can be found within the same terminal of a chemical synapse, as in Mauthner cells. | 1 | Gene expression + Signal Transduction |
For GPCRs generally, each mechanism of homologous desensitization begins with receptor phosphorylation by an associated G protein-coupled receptor kinase (GRK). GRKs selectively modify activated receptors such that no heterogeneous desensitization will occur. This phosphorylation then acts to recruit other proteins, such as arrestins, that participate in one or more of the following mechanisms. | 1 | Gene expression + Signal Transduction |
Electrowinning is the oldest industrial electrolytic process. The English chemist Humphry Davy obtained sodium metal in elemental form for the first time in 1807 by the electrolysis of molten sodium hydroxide.
Electrorefining of copper was first demonstrated experimentally by Maximilian, Duke of Leuchtenberg in 1847.
James Elkington patented the commercial process in 1865 and opened the first successful plant in Pembrey, Wales in 1870. The first commercial plant in the United States was the Balbach and Sons Refining and Smelting Company in Newark, New Jersey in 1883. | 0 | Metallurgy |
Ridaforolimus (AP23573, MK-8669), or deforolimus, is another rapamycin analogue that is not a prodrug for sirolimus. Like temsirolimus it can be administered intravenously, and oral formulation is being estimated for treatment of sarcoma. | 1 | Gene expression + Signal Transduction |
Synovial Sarcoma X chromosome breakpoint-2 (SSX2) proteins are known to localize in nucleus and work as a transcriptional repressor. In addition, expression of SSX2 is frequently observed in melanoma, but the role of the gene has not been evaluated. Thus, researchers have used the principle of ectopic expression to express SSX2 to different cell lines including cancer model cells. They found important phenotypes of ectopic SSX2 expression that is involved in tumorigenesis: 1) immediate induction of genomic instability, 2) long-term support of tumor cell growth. | 1 | Gene expression + Signal Transduction |
The lac operon of the model bacterium Escherichia coli was the first operon to be discovered and provides a typical example of operon function. It consists of three adjacent structural genes, a promoter, a terminator, and an operator. The lac operon is regulated by several factors including the availability of glucose and lactose. It can be activated by allolactose. Lactose binds to the repressor protein and prevents it from repressing gene transcription. This is an example of the derepressible (from above: negative inducible) model. So it is a negative inducible operon induced by presence of lactose or allolactose. | 1 | Gene expression + Signal Transduction |
The fineness of a precious metal object (coin, bar, jewelry, etc.) represents the weight of fine metal therein, in proportion to the total weight which includes alloying base metals and any impurities. Alloy metals are added to increase hardness and durability of coins and jewelry, alter colors, decrease the cost per weight, or avoid the cost of high-purity refinement. For example, copper is added to the precious metal silver to make a more durable alloy for use in coins, housewares and jewelry. Coin silver, which was used for making silver coins in the past, contains 90% silver and 10% copper, by mass. Sterling silver contains 92.5% silver and 7.5% of other metals, usually copper, by mass.
Various ways of expressing fineness have been used and two remain in common use: millesimal fineness expressed in units of parts per 1,000 and karats or carats used only for gold. Karats measure the parts per 24, so that 18 karat = = 75% and 24 karat gold is considered 100% gold. | 0 | Metallurgy |
Eutectoid steel can in principle be transformed completely into pearlite; hypoeutectoid steels can also be completely pearlitic if transformed at a temperature below the normal eutectoid. Pearlite can be hard and strong but is not particularly tough. It can be wear-resistant because of a strong lamellar network of ferrite and cementite. Examples of applications include cutting tools, high strength wires, knives, chisels, and nails. | 0 | Metallurgy |
The steel industry is often considered an indicator of economic progress, because of the critical role played by steel in infrastructural and overall economic development. In 1980, there were more than 500,000 U.S. steelworkers. By 2000, the number of steelworkers had fallen to 224,000.
The economic boom in China and India caused a massive increase in the demand for steel. Between 2000 and 2005, world steel demand increased by 6%. Since 2000, several Indian and Chinese steel firms have risen to prominence, such as Tata Steel (which bought Corus Group in 2007), Baosteel Group and Shagang Group. , though, ArcelorMittal is the world's largest steel producer. In 2005, the British Geological Survey stated China was the top steel producer with about one-third of the world share; Japan, Russia, and the US followed respectively.
The large production capacity of steel results in a significant amount of carbon dioxide emissions inherent related to the main production route. In 2019, it was estimated that 7 to 9% of the global carbon dioxide emissions resulted from the steel industry. Reduction of these emissions are expected to come from a shift in the main production route using cokes, more recycling of steel and the application of carbon capture and storage or carbon capture and utilization technology.
In 2008, steel began trading as a commodity on the London Metal Exchange. At the end of 2008, the steel industry faced a sharp downturn that led to many cut-backs. | 0 | Metallurgy |
Galvanic cells are extensions of spontaneous redox reactions, but have been merely designed to harness the energy produced from said reaction. For example, when one immerses a strip of zinc metal (Zn) in an aqueous solution of copper sulfate (CuSO), dark-colored solid deposits will collect on the surface of the zinc metal and the blue color characteristic of the Cu ion disappears from the solution. The depositions on the surface of the zinc metal consist of copper metal, and the solution now contains zinc ions. This reaction is represented by
: Zn (s) + Cu (aq) → Zn (aq) + Cu (s)
In this redox reaction, Zn is oxidized to Zn and Cu is reduced to Cu. When electrons are transferred directly from Zn to Cu , the enthalpy of reaction is lost to the surroundings as heat. However, the same reaction can be carried out in a galvanic cell, allowing some of the chemical energy released to be converted into electrical energy. In its simplest form, a half-cell consists of a solid metal (called an electrode) that is submerged in a solution; the solution contains cations (+) of the electrode metal and anions (−) to balance the charge of the cations. The full cell consists of two half-cells, usually connected by a semi-permeable membrane or by a salt bridge that prevents the ions of the more noble metal from plating out at the other electrode.
A specific example is the Daniell cell (see figure), with a zinc (Zn) half-cell containing a solution of ZnSO (zinc sulfate) and a copper (Cu) half-cell containing a solution of CuSO (copper sulfate). A salt bridge is used here to complete the electric circuit.
If an external electrical conductor connects the copper and zinc electrodes, zinc from the zinc electrode dissolves into the solution as Zn ions (oxidation), releasing electrons that enter the external conductor. To compensate for the increased zinc ion concentration, via the salt bridge zinc ions leave and anions enter the zinc half-cell. In the copper half-cell, the copper ions plate onto the copper electrode (reduction), taking up electrons that leave the external conductor. Since the Cu ions (cations) plate onto the copper electrode, the latter is called the cathode. Correspondingly the zinc electrode is the anode. The electrochemical reaction is
This is the same reaction as given in the previous example. In addition, electrons flow through the external conductor, which is the primary application of the galvanic cell.
As discussed under cell voltage, the electromotive force of the cell is the difference of the half-cell potentials, a measure of the relative ease of dissolution of the two electrodes into the electrolyte. The emf depends on both the electrodes and on the electrolyte, an indication that the emf is chemical in nature. | 0 | Metallurgy |
On a crushing and screening plant, punch plates or perforated plates are mostly used on scalper vibrating screens, after raw products pass on grizzly bars. Most likely installed on a tensioned deck, punch plates offer excellent wear life for high-impact and high material flow applications. | 0 | Metallurgy |
The Krupp-Renn process is suitable for producing pre-reduced iron ore from highly siliceous and acidic ores (CaO/SiO2 basicity index of 0.1 to 0.4), which begin generating a pasty slag at 1,200 °C. Additionally, due to the slag's acidity, it becomes vitreous, facilitating separation from the iron through easy crushing. Furthermore, this process is also ideal for treating ores with high concentrations of titanium dioxide. Due to its ability to cause slag to become especially infusible and viscous, ores that contain this oxide cannot be used with blast furnaces as they must remove all their production in liquid form. For this reason, the preferred ores for this technique are those that would become uneconomical if they had to be modified with basic additives, usually those with a low iron content (between 35 and 51%), and whose gangue needs to be neutralized.
Integrated into a steelmaking complex, the Krupp-Renn process provides an alternative to sinter plants or beneficiation processes, effectively eliminating waste rock and undesired elements like zinc, lead, and tin. Integrated into a steelmaking complex, the Krupp-Renn process provides an alternative to sinter plants or beneficiation processes, effectively eliminating waste rock and undesired elements like zinc, lead, and tin. In a blast furnace, these elements undergo vaporization-condensation cycles which progressively saturates the furnace. However, with the Krupp-Renn process, the high temperature of the fumes prevents condensation within the furnace, before they are retrieved by the dust-removal system. The process recovers by-products or extracts specific metals. The Luppen is subsequently remelted in either the blast furnace or the cupola furnace, or the Martin-Siemens furnace, because it involves melting a pre-reduced, iron-rich charge.
The process has been effective in treating ores abundant in nickel(II) oxide, vanadium, and other metals. Additionally, the process is applicable in the production of ferronickel. In this instance, saprolitic ores with a high magnesium content are as infusible as highly acidic ores, distinguishing their relevance to the process.
Direct reduction methods such as this one offer the flexibility of using any solid fuel and in this case, 240 to 300 kg of hard coal is needed to process one metric ton of iron ore that contains 30 to 40% iron. Assuming a consumption of 300 kg/ton of ore at 30%, the hard coal consumption is 800 kg per ton of iron. Additionally, 300 kg of coke is consumed during the smelting of Luppen in the blast furnace. When this ore is smelted entirely in the blast furnace, total fuel consumption remains the same. However, it only uses coke, which is a much more expensive fuel than hard coal.
However, using slags with over 60% silica content, making them acidic, contradicts metal desulfurization that demands highly basic slags. Consequently, 30% of the fuel's sulfur settles in the iron, entailing expensive after-treatments to eliminate it. | 0 | Metallurgy |
The third group of chemokines is known as the C chemokines (or γ chemokines), and is unlike all other chemokines in that it has only two cysteines; one N-terminal cysteine and one cysteine downstream. Two chemokines have been described for this subgroup and are called XCL1 (lymphotactin-α) and XCL2 (lymphotactin-β). | 1 | Gene expression + Signal Transduction |
Chemokines (), or chemotactic cytokines, are a family of small cytokines or signaling proteins secreted by cells that induce directional movement of leukocytes, as well as other cell types, including endothelial and epithelial cells. In addition to playing a major role in the activation of host immune responses, chemokines are important for biological processes, including morphogenesis and wound healing, as well as in the pathogenesis of diseases like cancers.
Cytokine proteins are classified as chemokines according to behavior and structural characteristics. In addition to being known for mediating chemotaxis, chemokines are all approximately 8–10 kilodaltons in mass and have four cysteine residues in conserved locations that are key to forming their 3-dimensional shape.
These proteins have historically been known under several other names including the SIS family of cytokines, SIG family of cytokines, SCY family of cytokines, Platelet factor-4 superfamily or intercrines. Some chemokines are considered pro-inflammatory and can be induced during an immune response to recruit cells of the immune system to a site of infection, while others are considered homeostatic and are involved in controlling the migration of cells during normal processes of tissue maintenance or development. Chemokines are found in all vertebrates, some viruses and some bacteria, but none have been found in other invertebrates.
Chemokines have been classified into four main subfamilies: CXC, CC, CX3C and C. All of these proteins exert their biological effects by interacting with G protein-linked transmembrane receptors called chemokine receptors, that are selectively found on the surfaces of their target cells. | 1 | Gene expression + Signal Transduction |
The Isa Process was originally developed for the CRL copper electrorefinery in Townsville. It was subsequently licensed to the Copper Range Company for its White Pine copper refinery.
The next licence issued was for an electrowinning application at the Broken Hill Associated Smelters (“BHAS”) lead smelter at Port Pirie, in South Australia. BHAS commissioned in 1985 a solvent extraction and electrowinning (“SX–EW”) to recover copper from copper–lead matte produced as a by-product of the lead smelting operations. The process used involves leaching the copper from the material using an acidic chloride–sulfate solution, followed by solvent extraction to concentrate the leached copper and electrowinning.
Electrowinning copper differs from electrorefining in that electrorefining uses a copper anode that is dissolved and redeposited on the cathode, while in electrowinning the copper is already in solution and is extracted from the solution by passing a current through the solution using an inert lead-alloy anode, and a cathode.
The chloride in the leach solution at Port Pirie proved to be a problem for the stainless steel cathodes of the Isa Process. A small amount of the chloride ions in the leach solution passed through the solvent into the electrolyte, leading to a reported chloride concentration of 80 milligrams per liter (“mg/L”) in the electrolyte. The presence of the chloride in the electrolyte caused pitting corrosion of the stainless steel cathode plates. After trying other types of stainless steel, BHAS switched to using titanium cathode plates.
Other electrowinning operations followed, including Gibraltar Mines’ McLeese Lake operation and Magma Copper’s San Manuel copper mine in 1986, the Mexicana de Cananea operation in Mexico in 1989, and the Gunpowder Copper Limited operation at Gunpowder in north-west Queensland 1990. These operations did not suffer the chloride corrosion problems experienced by BHAS. | 0 | Metallurgy |
ASF/SF2 has the ability to be phosphorylated at the serines in its RS domain by the SR specific protein kinase, SRPK1. SRPK1 and ASF/SF2 form an unusually stable complex of apparent K of 50nM. SRPK1 selectively phosphorylates up to twelve serines in the RS domain of ASF/SF2 through a directional and processive mechanism, moving from the C terminus to the N terminus. This multi-phosphorylation directs ASF/SF2 to the nucleus, influencing a number of protein-protein interactions associated with splicing. ASF/SF2's function in export of mature mRNA from the nucleus is dependent on its phosphorylation state; dephosphorylation of ASF/SF2 facilitates binding to TAP, while phosphorylation directs ASF/SF2 to nuclear speckles. Both phosphorylation and dephosphorylation of ASF/SF2 are important and necessary for proper splicing to occur, as sequential phosphorylation and dephosphorylation marks the transitions between stages in the splicing process. In addition, hypophosphorylation and hyperphosphorylation of ASF/SF2 by Clk/Sty can lead to inhibition of splicing. | 1 | Gene expression + Signal Transduction |
Calcium carbide is used:
* in the desulfurization of iron (pig iron, cast iron and steel)
* as a fuel in steelmaking to extend the scrap ratio to liquid iron, depending on economics.
* as a powerful deoxidizer at ladle treatment facilities. | 0 | Metallurgy |
Commonly studied regulons in bacteria are those involved in response to stress such as heat shock. The heat shock response in E. coli is regulated by the sigma factor
σ32 (RpoH), whose regulon has been characterized as containing at least 89 open reading frames.
Regulons involving virulence factors in pathogenic bacteria are of particular research interest; an often-studied example is the phosphate regulon in E. coli, which couples phosphate homeostasis to pathogenicity through a two-component system. Regulons can sometimes be pathogenicity islands.
The Ada regulon in E. coli is a well-characterized example of a group of genes involved in the adaptive response form of DNA repair.
Quorum sensing behavior in bacteria is a commonly cited example of a modulon or stimulon, though some sources describe this type of intercellular auto-induction as a separate form of regulation. | 1 | Gene expression + Signal Transduction |
Mouse Genome Informatics (MGI) is a free, online database and bioinformatics resource hosted by The Jackson Laboratory, with funding by the National Human Genome Research Institute (NHGRI), the National Cancer Institute (NCI), and the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). MGI provides access to data on the genetics, genomics and biology of the laboratory mouse to facilitate the study of human health and disease. The database integrates multiple projects, with the two largest contributions coming from the Mouse Genome Database and Mouse Gene Expression Database (GXD). , MGI contains data curated from over 230,000 publications.
The MGI resource was first published online in 1994 and is a collection of data, tools, and analyses created and tailored for use in the laboratory mouse, a widely used model organism. It is "the authoritative source of official names for mouse genes, alleles, and strains", which follow the guidelines established by the International Committee on Standardized Genetic Nomenclature for Mice. The history and focus of Jackson Laboratory research and production facilities generates tremendous knowledge and depth which researchers can mine to advance their research. A dedicated community of mouse researchers, worldwide enhances and contributes to the knowledge as well. This is an indispensable tool for any researcher using the mouse as a model organism for their research, and for researchers interested in genes that share homology with the mouse genes. Various mouse research support resources including animal collections and free colony management software are also available at the MGI site. | 1 | Gene expression + Signal Transduction |
Electropolishing, also known as electrochemical polishing, anodic polishing, or electrolytic polishing (especially in the metallography field), is an electrochemical process that removes material from a metallic workpiece, reducing the surface roughness by levelling micro-peaks and valleys, improving the surface finish. Electropolishing is often compared to, but distinctly different from, electrochemical machining. It is used to polish, passivate, and deburr metal parts. It is often described as the reverse of electroplating. It may be used in lieu of abrasive fine polishing in microstructural preparation. | 0 | Metallurgy |
The Hepatitis C virus requires the CD81 co-receptor for infection. Studies suggest that the tight junction protein Claudin-1 (CLDN1) may also play a part in HCV entry. Claudin family abnormalities are also common in hepatocellular carcinoma, which can result from HPV infection. | 1 | Gene expression + Signal Transduction |
AREsite is a database of AU-rich elements (ARE) in vertebrate mRNA 3'-untranslated regions (UTRs). AU-rich elements are involved in the control of gene expression. They are the most common determinant of RNA stability in mammalian cells. The most recent version of AREsite is called AREsite 2. It represents an update that allows for more detailed analysis of ARE, GRE, and URE (AU, GU, and U-rich elements). | 1 | Gene expression + Signal Transduction |
Commonly used protein production systems include those derived from bacteria, yeast, baculovirus/insect, mammalian cells, and more recently filamentous fungi such as Myceliophthora thermophila. When biopharmaceuticals are produced with one of these systems, process-related impurities termed host cell proteins also arrive in the final product in trace amounts. | 1 | Gene expression + Signal Transduction |
Unlike small interfering RNA (siRNA) therapeutics that turn over within a cell and consequently only silence genes transiently, DNA constructs are continually transcribed, replenishing the cellular ‘dose’ of short-hairpin RNA (shRNA), thereby enabling long-term silencing of targeted genes. The ddRNAi mechanism, therefore, offers the potential for ongoing clinical benefit with reduced medical intervention. | 1 | Gene expression + Signal Transduction |
Mass spectrometry is a way to quantify RNA modifications. More often than not, modifications cause an increase in mass for a given nucleoside. This gives a characteristic readout for the nucleoside and the modified counterpart. Moreover, mass spectrometry allows the investigation of modification dynamics by labelling RNA molecules with stable (non-radioactive) heavy isotopes in vivo. Due to the defined mass increase of heavy isotope labeled nucleosides they can be distinguished from their respective unlabelled isotopomeres by mass spectrometry. This method, called NAIL-MS (nucleic acid isotope labelling coupled mass spectrometry), enables a variety of approaches to investigate RNA modification dynamics. | 1 | Gene expression + Signal Transduction |
* CTDP1
* CTDSP1, CTDSP2, CTDSPL
* DULLARD
* EPM2A
* ILKAP
* MDSP
* PGAM5
* PHLPP1, PHLPP2
* PPEF1, PPEF2
* PPM1A, PPM1B, PPM1D, PPM1E, PPM1F, PPM1G, PPM1H, PPM1J, PPM1K, PPM1L, PPM1M, PPM1N
* PPTC7
* PTPMT1
* SSU72
* UBLCP1 | 1 | Gene expression + Signal Transduction |
Translational regulation refers to the control of the levels of protein synthesized from its mRNA. This regulation is vastly important to the cellular response to stressors, growth cues, and differentiation. In comparison to transcriptional regulation, it results in much more immediate cellular adjustment through direct regulation of protein concentration. The corresponding mechanisms are primarily targeted on the control of ribosome recruitment on the initiation codon, but can also involve modulation of peptide elongation, termination of protein synthesis, or ribosome biogenesis. While these general concepts are widely conserved, some of the finer details in this sort of regulation have been proven to differ between prokaryotic and eukaryotic organisms. | 1 | Gene expression + Signal Transduction |
Senescence in cells is a state in which cells are metabolically active but are no longer able to replicate. pRb is an important regulator of senescence in cells and since this prevents proliferation, senescence is an important antitumor mechanism. pRb may occupy E2F-regulated promoters during senescence. For example, pRb was detected on the cyclin A and PCNA promoters in senescent cells. | 1 | Gene expression + Signal Transduction |
Super-enhancers have been most commonly identified by locating genomic regions that are highly enriched in ChIP-Seq signal. ChIP-Seq experiments targeting master transcription factors and co-factors like Mediator or BRD4 have been used, but the most frequently used is H3K27ac-marked nucleosomes. The program “ROSE” (Rank Ordering of Super-Enhancers) is commonly used to identify super-enhancers from ChIP-Seq data. This program stitches together previously identified enhancer regions and ranks these stitched enhancers by their ChIP-Seq signal. The stitching distance selected to combine multiple individual enhancers into larger domains can vary. Because some markers of enhancer activity also are enriched in promoters, regions within promoters of genes can be disregarded. ROSE separates super-enhancers from typical enhancers by their exceptional enrichment in a mark of enhancer activity. Homer is another tool that can identify super-enhancers. | 1 | Gene expression + Signal Transduction |
A more detailed knowledge of the structures of metals, and binary and ternary phases of metals and non metals shows that:
*generally at low concentrations of the small atom, the phase can be described as a solution, and this approximates to the historical description of an interstitial compound above.
*at higher concentrations of the small atom, phases with different lattice structures may be present, and these may have a range of stoichiometries.
One example is the solubility of carbon in iron. The form of pure iron stable between 910 °C and 1390 °C, γ-iron, forms a solid solution with carbon termed austenite which is also known as steel. | 0 | Metallurgy |
Certain NMTs are therapeutic targets for development of drugs against bacterial infections. Myristoylation has been shown to be necessary for the survival of a number of disease-causing fungi, among them C. albicans and C. neoformans. In addition to prokaryotic bacteria, the NMTs of numerous disease-causing eukaryotic organisms have been identified as drug targets as well. Proper NMT functioning in the protozoa Leishmania major and Leishmania donovani (leishmaniasis), Trypanosoma brucei (African sleeping sickness), and P. falciparum (malaria) is necessary for survival of the parasites. Inhibitors of these organisms are under current investigation. A pyrazole sulfonamide inhibitor has been identified that selectively binds T. brucei, competing for the peptide binding site, thus inhibiting enzymatic activity and eliminating the parasite from the bloodstream of mice with African sleeping sickness. | 1 | Gene expression + Signal Transduction |
Ballast tanks do not corrode uniformly throughout the tank. Each region behaves distinctively, according to it electrochemical loading. The differences can especially be seen in empty ballast tanks. The upper sections usually corrode but the lower sections will blister.
A ballast tank has three distinct sections: 1) upper, 2) mid or "boottop" area and, 3) the "double bottom" or lower wing sections. The upper regions are constantly affected by weather. This area experiences a high degree of thermal cycling and mechanical damage through vibration. This area tends to undergo anodic oxidation more rapidly than other sections and will weaken more rapidly. This ullage or headspace area contains more oxygen and thus speeds atmospheric corrosion, as evidenced by the appearance of rust scales.
In the midsection corrodes more slowly than upper or the bottom sections of the tank.
Double bottoms are prone to cathodic blistering. Temperatures in this area are much lower due to the cooling of the sea. If this extremely cathodic region is placed close to an anodic source (e.g. a corroding ballast pipe), cathodic blistering may occur especially where the epoxy coating is relatively new. Mud retained in ballast water can lead to microbial corrosion. | 0 | Metallurgy |
Both hypoxic conditions and serum deprivation induced increased expression of SFRP1 in leiomyoma cells. However, the smooth muscle cells cultured from the myometrium showed no significant correlation between SFRP1 expression and oxygen concentration. This suggests that SFRP1 may protect the cells from the damage caused by these stresses. | 1 | Gene expression + Signal Transduction |
* Phase diagram determination for the Aluminium-Copper age-hardening alloy system. This was to lead to further discoveries at Fulmer on the influence of trace elements on nucleation and grain growth. Fulmer used this to formulate and patent alloys with high strength and toughness and good creep resistance for the skins of high-performance aircraft.
* The sub-halide catalytic distillation method for primary aluminium production. Dr Gross began this work at International Alloys and, when Fulmer was founded, this became Fulmer's first contract. He speculated and then proved that aluminium has a subhalide AlCl. He devised a method by which pure Aluminium can be catalytically distilled from any aluminium-containing alloy or mixture or from scrap aluminium using the following reversible reaction:
:: 2Al(solid) + AlCl(gas) </span> 3AlCl(gas)
: The forward reaction is favoured at high temperature and low partial pressure of AlCl. On cooling, the reaction reverses; aluminium condenses and the trichloride can be recirculated. Analogous methods were developed for the extraction of beryllium and titanium.
* Determination of thermodynamic data by high accuracy calorimetry. Heats of formation and free energies of formation were needed for the assessment of potential rocket fuels. Fulmer established equipment and skills for very accurate measurement of heats of formation and heats of reaction. Reaction conditions could be extreme: burning in fluorine might have to be contained or temperatures up to 2000 °C might be needed. Calorimeter fluid temperatures were measured to 2×10 K. Over the many years that this work continued, Fulmer established thermodynamic data for a wide range of metal halides, intermetallics, mixed oxides and other compounds.
* Aluminium-tin alloys for plain bearing shells. Fulmer's researchers applied to the aluminum-tin alloy system the fundamental work of C S Smith on the relationship of interfacial energy and microstructure. They established a process of cold work and recrystallization which converts the weak as-cast structure, in which aluminium grains are surrounded by tin, to one in which tin is dispersed in a strong aluminium matrix. The aluminium provides the load-bearing required for a plain bearing while the tin gives the required bearing properties. For many years these aluminium-tin bearings were used in most diesel engines and they are still in current use.
* X-ray diffraction crystallography of metals and alloys for phase diagram determination.
* Interfacial tension and wetting behaviour of liquid sodium.
* Vitreous enamelling of aluminium to give high integrity electrically resistant coatings.
* Measurements of stress corrosion and corrosion fatigue of light alloys.
* Studies of deformation processes in difficult metals such as beryllium and chromium. | 0 | Metallurgy |
STAT6-mediated signaling pathway is required for the development of T-helper type 2 (Th2) cells and Th2 immune response. Expression of Th2 cytokines, including IL-4, IL-13, and IL-5, was reduced in STAT6-deficient mice. STAT 6 protein is crucial in IL4 mediated biological responses. It was found that STAT6 induce the expression of BCL2L1/BCL-X(L), which is responsible for the anti-apoptotic activity of IL4. IL-4 stimulates the phosphorylation of IL-4 receptor, which recruits cytosolic STAT6 by its SH2 domain and STAT6 is phosphorylated on tyrosine 641 (Y641) by JAK1, which results in the dimerization and nuclear translocation of STAT6 to activate target genes. Knockout studies in mice suggested the roles of this gene in differentiation of T helper 2 (Th2), expression of cell surface markers, and class switch of immunoglobulins.
Activation of STAT6 signaling pathway is necessary in macrophage function, and is required for the M2 subtype activation of macrophages. STAT6 protein also regulates other transcription factor as Gata3, which is important regulator of Th2 differentiation. STAT6 is also required for the development of IL-9-secreting T cells.
STAT6 also plays a critical role in Th2 lung inflammatory responses including clearance of parasitic infections and in the pathogenesis of asthma. Th2-cell derived cytokines as IL-4 and IL-13 induce the production of IgE which is a major mediator in allergic response. Association studies searching for relation of polymorphisms in STAT6 with IgE level or asthma discovered a few polymorphisms significantly associated with examined traits. Only two polymorphisms showed repeatedly significant clinical association and/or functional effect on STAT6 function (GT repeats in exon 1 and rs324011 polymorphism in intron 2). | 1 | Gene expression + Signal Transduction |
Quorum sensing regulates a menagerie of aspects in Bacillota including the production of ropB-like proteins in Streptococcus pneumoniae and S. pyogenes. Similarities in the pH sensitivity of the cell signaling mechanisms were found in pneumococci, S. mutans, and Staphylococcus aureus as well. | 1 | Gene expression + Signal Transduction |
A number of techniques exist to quantitatively analyze metallographic specimens. These techniques are valuable in the research and production of all metals and alloys and non-metallic or composite materials.
Microstructural quantification is performed on a prepared, two-dimensional plane through the three-dimensional part or component. Measurements may involve simple metrology techniques, e.g., the measurement of the thickness of a surface coating, or the apparent diameter of a discrete second-phase particle, (for example, spheroidal graphite in ductile iron). Measurement may also require application of stereology to assess matrix and second-phase structures. Stereology is the field of taking 0-, 1- or 2-dimensional measurements on the two-dimensional sectioning plane and estimating the amount, size, shape or distribution of the microstructure in three dimensions. These measurements may be made using manual procedures with the aid of templates overlaying the microstructure, or with automated image analyzers. In all cases, adequate sampling must be made to obtain a proper statistical basis for the measurement. Efforts to eliminate bias are required.
Some of the most basic measurements include determination of the volume fraction of a phase or constituent, measurement of the grain size in polycrystalline metals and alloys, measurement of the size and size distribution of particles, assessment of the shape of particles, and spacing between particles.
Standards organizations, including ASTM International's Committee E-4 on Metallography and some other national and international organizations, have developed standard test methods describing how to characterize microstructures quantitatively.
For example, the amount of a phase or constituent, that is, its volume fraction, is defined in ASTM E 562; manual grain size measurements are described in ASTM E 112 (equiaxed grain structures with a single size distribution) and E 1182 (specimens with a bi-modal grain size distribution); while ASTM E 1382 describes how any grain size type or condition can be measured using image analysis methods. Characterization of nonmetallic inclusions using standard charts is described in ASTM E 45 (historically, E 45 covered only manual chart methods and an image analysis method for making such chart measurements was described in ASTM E 1122. The image analysis methods are currently being incorporated into E 45). A stereological method for characterizing discrete second-phase particles, such as nonmetallic inclusions, carbides, graphite, etc., is presented in ASTM E 1245. | 0 | Metallurgy |
Silver standards refer to the standards of millesimal fineness for the silver alloy used in the manufacture or crafting of silver objects. This list is organized from highest to lowest millesimal fineness, or purity of the silver.
* Fine silver has a millesimal fineness of 999. Also called pure silver, or three nines fine, fine silver contains 99.9% silver, with the balance being some trace amounts of impurities. This grade of silver is used to make bullion bars for international commodities trading and investment in silver. In the modern world, fine silver is understood to be too soft for general use.
* Britannia silver has a millesimal fineness of at least 958. The alloy is 95.84% pure silver and 4.16% copper or other metals. The Britannia standard was developed in Britain in 1697 to help prevent British sterling silver coins from being melted to make silver plate. It was obligatory in Britain between 1697 and 1720, when the sterling silver standard was restored. It became an optional standard thereafter.
* The French 1st standard has a milessimal fineness of 950. The French 1st alloy is 95% silver and 5% copper or other metals.
* 91 zolotnik Russian silver has a millesimal fineness of 947. The zolotnik (Russian золотник, from the Russian zoloto, or золото, meaning gold) was used in Russia as early as the 11th century to denote the weight of gold coins. In its earliest usage, the zolotnik was 1/96 of a pound, but it later was changed to represent 1/72 of a pound. Ninety-one (91) zolotniks have the equivalent millesimal fineness of 947[9]. Thus, the alloy contains 94.79% pure silver and 5.21% copper or other metals.
* Sterling silver has a millesimal fineness of 925. The sterling silver alloy is 92.5% pure silver and 7.5% copper or other metals. This alloy was used by the United Kingdom from the early 12th century, and Canada, Australia and other countries associated with the British Empire (and later Commonwealth) from the 19th century up to the mid-20th century when debasement took place; Sterling silver’s copper content means that it has a stronger tendency to tarnish than other alloys used in coins.
*Following a program of debasements in the early-to-mid 20th century, circulating Canadian coinage (with the exception of the nickel) had a millesimal fineness of 800 until 1968. The alloy used contained 80% silver and 20% copper.
* 88 zolotnik Russian silver has the equivalent millesimal fineness of 916[6]. The alloy contains 91.66% pure silver and 8.34% copper or other metals. (The description of the zolotnik is above.)
* Coin silver has a millesimal fineness of 900. The term "coin silver" was derived from the fact that much of it was made from melting down silver coins. It is important here to note that there are differences between the coin silver standard and the coin silver alloy, as actually used in making silver objects. The coin silver standard in the United States was 90% silver and 10% copper, as dictated by US FTC guidelines. However, in silversmithing, coins could come from other nations besides the United States, and thus coin silver objects could vary from 750 millesimal fineness (75% silver) to 900 (90% silver). Coins were used as a source of silver in the US until 1868, shortly after the discovery of the Comstock silver lodes in Nevada, which provided a significant source of silver. Around this time the sterling standard was adopted by the American silver industry.
* 84 zolotnik Russian silver has the equivalent millesimal fineness of 875. The alloy contains 87.5% pure silver and 12.5% copper or other metals. (See above for description of the zolotnik.)
* has a millesimal fineness of 830. The Scandinavian silver alloy contains 83% pure silver and 17% copper or other metals.
* German silver will be marked with a millesimal fineness of 800 or 835 (80% or 83.5% pure silver). Any items simply marked "German silver", "nickel silver" or "Alpaca" have no silver content at all, but are mere alloys of other base metals.
* Decoplata has the equivalent millesimal fineness of 720. The alloy contains 72% pure silver and 28% copper. It was used by a number of countries between the 19th century and the present, but it is most associated with coins made in Mexico and the Netherlands in the mid-20th Century. | 0 | Metallurgy |
Microarray data is difficult to exchange due to the lack of standardization in platform fabrication, assay protocols, and analysis methods. This presents an interoperability problem in bioinformatics. Various grass-roots open-source projects are trying to ease the exchange and analysis of data produced with non-proprietary chips:
For example, the "Minimum Information About a Microarray Experiment" (MIAME) checklist helps define the level of detail that should exist and is being adopted by many journals as a requirement for the submission of papers incorporating microarray results. But MIAME does not describe the format for the information, so while many formats can support the MIAME requirements, no format permits verification of complete semantic compliance. The "MicroArray Quality Control (MAQC) Project" is being conducted by the US Food and Drug Administration (FDA) to develop standards and quality control metrics which will eventually allow the use of MicroArray data in drug discovery, clinical practice and regulatory decision-making. The MGED Society has developed standards for the representation of gene expression experiment results and relevant annotations. | 1 | Gene expression + Signal Transduction |
miR-324-5p contributes to cardiac disease pathophysiology and cardiomyocite death through translational inhibition of Mtfr1, leading to reduced mitochondrial fission, apoptosis, and myocardial infarction. | 1 | Gene expression + Signal Transduction |
There are two types of genes: protein coding genes and noncoding genes. Noncoding genes are an important part of non-coding DNA and they include genes for transfer RNA and ribosomal RNA. These genes were discovered in the 1960s. Prokaryotic genomes contain genes for a number of other noncoding RNAs but noncoding RNA genes are much more common in eukaryotes.
Typical classes of noncoding genes in eukaryotes include genes for small nuclear RNAs (snRNAs), small nucleolar RNAs (sno RNAs), microRNAs (miRNAs), short interfering RNAs (siRNAs), PIWI-interacting RNAs (piRNAs), and long noncoding RNAs (lncRNAs). In addition, there are a number of unique RNA genes that produce catalytic RNAs.
Noncoding genes account for only a few percent of prokaryotic genomes but they can represent a vastly higher fraction in eukaryotic genomes. In humans, the noncoding genes take up at least 6% of the genome, largely because there are hundreds of copies of ribosomal RNA genes. Protein-coding genes occupy about 38% of the genome; a fraction that is much higher than the coding region because genes contain large introns.
The total number of noncoding genes in the human genome is controversial. Some scientists think that there are only about 5,000 noncoding genes while others believe that there may be more than 100,000 (see the article on Non-coding RNA). The difference is largely due to debate over the number of lncRNA genes. | 1 | Gene expression + Signal Transduction |
The human CCR4-Not complex is composed of structural (non-catalytic) subunits and those that have exonuclease and E3 ligase activity. Some but not all of the human subunits are conserved in budding yeast. In yeast the complex has nine core subunits, comprising Ccr4 (carbon catabolite repression), Caf proteins (Ccr4 associated factor) (Caf1, Caf40, Caf130) and Not proteins (Not1, Not2, Not3, Not4, and Not5).
Molecular weight of human subunits from Uniprot. | 1 | Gene expression + Signal Transduction |
It is based on the principle that the intensity of light received by the observer depends upon the distance of the observer from the source and the temperature of the distant source. A modern pyrometer has an optical system and a detector. The optical system focuses the thermal radiation onto the detector. The output signal of the detector (temperature T) is related to the thermal radiation or irradiance of the target object through the Stefan–Boltzmann law, the constant of proportionality σ, called the Stefan–Boltzmann constant and the emissivity ε of the object:
This output is used to infer the object's temperature from a distance, with no need for the pyrometer to be in thermal contact with the object; most other thermometers (e.g. thermocouples and resistance temperature detectors (RTDs)) are placed in thermal contact with the object and allowed to reach thermal equilibrium.
Pyrometry of gases presents difficulties. These are most commonly overcome by using thin-filament pyrometry or soot pyrometry. Both techniques involve small solids in contact with hot gases. | 0 | Metallurgy |
Grain growth has long been studied primarily by the examination of sectioned, polished and etched samples under the optical microscope. Although such methods enabled the collection of a great deal of empirical evidence, particularly with regard to factors such as temperature or composition, the lack of crystallographic information limited the development of an understanding of the fundamental physics. Nevertheless, the following became well-established features of grain growth:
# Grain growth occurs by the movement of grain boundaries and also by coalescence (i.e. like water droplets)
#Grain growth competition between Ordered coalescence and the movement of grain boundaries
# Boundary movement may be discontinuous and the direction of motion may change suddenly during abnormal grain growth.
# One grain may grow into another grain whilst being consumed from the other side
# The rate of consumption often increases when the grain is nearly consumed
# A curved boundary typically migrates towards its centre of curvature | 0 | Metallurgy |
Eshelby work helped shape the fields of defect mechanics and micromechanics of inhomogeneous solids for fifty years, including the controlling mechanisms of plastic deformation and fracture.The scientific phenomenon called Eshelby's inclusion is named after this scientist, and points at an ellipsoidal subdomain in an infinite homogeneous body, subjected to a uniform transformation strain. | 0 | Metallurgy |
Cerrosafe is a fusible alloy with a low melting point. It is a non-eutectic mixture consisting of 42.5% bismuth, 37.7% lead, 11.3% tin, and 8.5% cadmium that melts between and . It is useful for making reference castings whose dimensions can be correlated to those of the mold or other template due to its well-known thermal expansion properties during cooling. The alloy contracts during the first 30 minutes, allowing easy removal from a mold, then expands during the next 30 minutes to return to the exact original size. It then continues expanding at a known rate for 200 hours, allowing conversion of measurements of the casting back to those of the mold. | 0 | Metallurgy |
*PLC-ε (230-260kDa ) is activated by Ras and Rho GTPases.
*PLC-ζ (75kDa) is thought to play an important role in vertebrate fertilization by producing intracellular calcium oscillations important for the start of embryonic development. However, the mechanism of activation still remains unclear. This isoform is also capable of entering the early-formed pronucleus after fertilization, which seems to coincide with the cessation of calcium mobilization. It, like PLC-δ1 and PLC-β, possesses nuclear export and localization sequences.
*PLC-η has been implicated in neuronal functioning. | 1 | Gene expression + Signal Transduction |
PA is a unique phospholipid in that it has a small highly charged head group that is very close to the glycerol backbone. PA is known to play roles in both vesicle fission and fusion, and these roles may relate to the biophysical properties of PA.
At sites of membrane budding or fusion, the membrane becomes or is highly curved. A major event in the budding of vesicles, such as transport carriers from the Golgi, is the creation and subsequent narrowing of the membrane neck. Studies have suggested that this process may be lipid-driven, and have postulated a central role for DAG due to its, likewise, unique molecular shape. The presence of two acyl chains but no headgroup results in a large negative curvature in membranes.
The LPAAT BARS-50 has also been implicated in budding from the Golgi. This suggests that the conversion of lysoPA into PA might affect membrane curvature. LPAAT activity doubles the number of acyl chains, greatly increasing the cross-sectional area of the lipid that lies ‘within’ the membrane while the surface headgroup remains unchanged. This can result in a more negative membrane curvature. Researchers from Utrecht University have looked at the effect of lysoPA versus PA on membrane curvature by measuring the effect these have on the transition temperature of PE from lipid bilayers to nonlamellar phases using P-NMR. The curvature induced by these lipids was shown to be dependent not only on the structure of lysoPA versus PA but also on dynamic properties, such as the hydration of head groups and inter- and intramolecular interactions. For instance, Ca may interact with two PAs to form a neutral but highly curved complex. The neutralisation of the otherwise repulsive charges of the headgroups and the absence of any steric hindrance enables strong intermolecular interactions between the acyl chains, resulting in PA-rich microdomains. Thus in vitro, physiological changes in pH, temperature, and cation concentrations have strong effects on the membrane curvature induced by PA and lysoPA.
The interconversion of lysoPA, PA, and DAG – and changes in pH and cation concentration – can cause membrane bending and destabilisation, playing a direct role in membrane fission simply by virtue of their biophysical properties. However, though PA and lysoPA have been shown to affect membrane curvature in vitro; their role in vivo is unclear.
The roles of lysoPA, PA, and DAG in promoting membrane curvature do not preclude a role in recruiting proteins to the membrane. For instance, the Ca requirement for the fusion of complex liposomes is not greatly affected by the addition of annexin I, though it is reduced by PLD. However, with annexin I and PLD, the extent of fusion is greatly enhanced, and the Ca requirement is reduced almost 1000-fold to near physiological levels.
Thus the metabolic, biophysical, recruitment, and signaling roles of PA may be interrelated. | 1 | Gene expression + Signal Transduction |
During the 1980s, a class of thermal spray processes called high velocity oxy-fuel spraying was developed. A mixture of gaseous or liquid fuel and oxygen is fed into a combustion chamber, where they are ignited and combusted continuously. The resultant hot gas at a pressure close to 1 MPa emanates through a converging–diverging nozzle and travels through a straight section. The fuels can be gases (hydrogen, methane, propane, propylene, acetylene, natural gas, etc.) or liquids (kerosene, etc.). The jet velocity at the exit of the barrel (>1000 m/s) exceeds the speed of sound. A powder feed stock is injected into the gas stream, which accelerates the powder up to 800 m/s. The stream of hot gas and powder is directed towards the surface to be coated. The powder partially melts in the stream, and deposits upon the substrate. The resulting coating has low porosity and high bond strength.
HVOF coatings may be as thick as 12 mm (1/2"). It is typically used to deposit wear and corrosion resistant coatings on materials, such as ceramic and metallic layers. Common powders include WC-Co, chromium carbide, MCrAlY, and alumina. The process has been most successful for depositing cermet materials (WC–Co, etc.) and other corrosion-resistant alloys (stainless steels, nickel-based alloys, aluminium, hydroxyapatite for medical implants, etc.). | 0 | Metallurgy |
Underground corrosion control engineers collect soil samples to test soil chemistry for corrosive factors such as pH, minimum soil resistivity, chlorides, sulfates, ammonia, nitrates, sulfide, and redox potential. They collect samples from the depth that infrastructure will occupy, because soil properties may change from strata to strata. The minimum test of in-situ soil resistivity is measured using the Wenner four pin method if often performed to judge a sites corrosivity. However, during a dry period, the test may not show actual corrosivity, since underground condensation can leave soil in contact with buried metal surfaces more moist. This is why measuring a soils minimum or saturated resistivity is important. Soil resistivity testing alone does not identify corrosive elements. Corrosion engineers can investigate locations experiencing active corrosion using above ground survey methods and design corrosion control systems such as cathodic protection to stop or reduce the rate of corrosion.
Geotechnical engineers typically do not practice corrosion engineering, and refer clients to a corrosion engineer if soil resistivity is below 3,000 ohm-cm or less, depending the soil corrosivity categorization table they read. Unfortunately, an old dairy farm can have soil resistivities above 3,000 ohm-cm and still contain corrosive ammonia and nitrate levels that corrode copper piping or grounding rods. A general saying about corrosion is, "If the soil is great for farming, it is great for corrosion." | 0 | Metallurgy |
Mill scale can be used as a raw material in granular refractory. When this refractory is cast and preheated, these scales provide escape routes for the evaporating water vapor, thus preventing cracks and resulting in a strong, monolithic structure. | 0 | Metallurgy |
ATP-dependent chromatin-remodeling complexes regulate gene expression by either moving, ejecting or restructuring nucleosomes. These protein complexes have a common ATPase domain and energy from the hydrolysis of ATP allows these remodeling complexes to reposition nucleosomes (often referred to as "nucleosome sliding") along the DNA, eject or assemble histones on/off of DNA or facilitate exchange of histone variants, and thus creating nucleosome-free regions of DNA for gene activation. Also, several remodelers have DNA-translocation activity to carry out specific remodeling tasks.
All ATP-dependent chromatin-remodeling complexes possess a sub unit of ATPase that belongs to the SNF2 superfamily of proteins. In association to the sub unit's identity, two main groups have been classified for these proteins. These are known as the SWI2/SNF2 group and the imitation SWI (ISWI) group. The third class of ATP-dependent complexes that has been recently described contains a Snf2-like ATPase and also demonstrates deacetylase activity. | 1 | Gene expression + Signal Transduction |
Human satellite II is an exceptionally high-copy but unexplored sequence of the human genome thought of as junk DNA has a surprising ability to impact master regulators of our genome, and it goes awry in 50 percent of tumors.
Because HSAT-II DNA is normally methylated (a form of gene regulation), it remains dormant in healthy cells. For this reason, the HSAT-II hasn't been extensively studied and has not been thought to have a function. Due to its similarities to Human Satellite 3, the primary sequence component of the traditional human satellite fraction II (also known as Human Satellite 2 or HSat2) is sometimes incorrectly marked by RepeatMasker. In RepeatMasker annotations, both repeats frequently appear as a mixed pattern of "HSATII" and "(CATTC)n simple repeats." Based on this problem, Oxford Nanopore Technologies researcher used their own characterization of these sequences inside the CHM13 genome To further classify each HSat2 array into its previously identified subfamilies.
In fact, standard genomic experiments intentionally screen HSAT-II out of the results. Both herpes viruses and cancer manipulate this same pathway causing genetic instability and disease. | 1 | Gene expression + Signal Transduction |
Metallic glasses based on the Mg-Zn-Ca ternary alloy system only consist of the elements which already exist inside the human body. As such, it is being explored as a potential bioresorbable biomaterial for use in orthopaedic applications. | 0 | Metallurgy |
Basic helix-loop-helix leucine zipper transcription factors are, as their name indicates, transcription factors containing both Basic helix-loop-helix and leucine zipper motifs.
Examples include Microphthalmia-associated transcription factor and Sterol regulatory element binding protein (SREBP). | 1 | Gene expression + Signal Transduction |
Protein kinase A, more precisely known as adenosine 3,5-monophosphate (cyclic AMP)-dependent protein kinase, abbreviated to PKA, was discovered by chemists Edmond H. Fischer and Edwin G. Krebs in 1968. They won the Nobel Prize in Physiology or Medicine in 1992 for their work on phosphorylation and dephosphorylation and how it relates to PKA activity.
PKA is one of the most widely researched protein kinases, in part because of its uniqueness; out of 540 different protein kinase genes that make up the human kinome, only one other protein kinase, casein kinase 2, is known to exist in a physiological tetrameric complex, meaning it consists of four subunits.
The diversity of mammalian PKA subunits was realized after Dr. Stan McKnight and others identified four possible catalytic subunit genes and four regulatory subunit genes. In 1991, Susan Taylor and colleagues crystallized the PKA Cα subunit, which revealed the bi-lobe structure of the protein kinase core for the very first time, providing a blueprint for all the other protein kinases in a genome (the kinome). | 1 | Gene expression + Signal Transduction |
The G protein-coupled receptor kinases (GRKs) are protein kinases that phosphorylate only active GPCRs. G-protein-coupled receptor kinases (GRKs) are key modulators of G-protein-coupled receptor (GPCR) signaling. They constitute a family of seven mammalian serine-threonine protein kinases that phosphorylate agonist-bound receptor. GRKs-mediated receptor phosphorylation rapidly initiates profound impairment of receptor signaling and desensitization. Activity of GRKs and subcellular targeting is tightly regulated by interaction with receptor domains, G protein subunits, lipids, anchoring proteins and calcium-sensitive proteins.
Phosphorylation of the receptor can have two consequences:
# Translocation: The receptor is, along with the part of the membrane it is embedded in, brought to the inside of the cell, where it is dephosphorylated within the acidic vesicular environment and then brought back. This mechanism is used to regulate long-term exposure, for example, to a hormone, by allowing resensitisation to follow desensitisation. Alternatively, the receptor may undergo lysozomal degradation, or remain internalised, where it is thought to participate in the initiation of signalling events, the nature of which depending on the internalised vesicle's subcellular localisation.
# Arrestin linking: The phosphorylated receptor can be linked to arrestin molecules that prevent it from binding (and activating) G proteins, in effect switching it off for a short period of time. This mechanism is used, for example, with rhodopsin in retina cells to compensate for exposure to bright light. In many cases, arrestin's binding to the receptor is a prerequisite for translocation. For example, beta-arrestin bound to β-adrenoreceptors acts as an adaptor for binding with clathrin, and with the beta-subunit of AP2 (clathrin adaptor molecules); thus, the arrestin here acts as a scaffold assembling the components needed for clathrin-mediated endocytosis of β-adrenoreceptors. | 1 | Gene expression + Signal Transduction |
PTEN is a tumor suppressor that inhibits the PI3K/AKT pathway. PTEN inhibitors, such as bisperoxovanadium, can enhance the PI3K/AKT pathway to promote cell migration, survival and proliferation. While there are some concerns over possible cell cycle dysregulation and tumorigenesis, temporary and moderate PTEN inhibition may confer neuroprotection against traumatic brain injury and improve CNS recovery by reestablishing lost connections by axonogenesis. Medicinal value of PTEN inhibitors remains to be determined. | 1 | Gene expression + Signal Transduction |
The Seebeck effect refers to the development of an electromotive force across two points of an electrically conducting material when there is a temperature difference between those two points.
Under open-circuit conditions where there is no internal current flow, the gradient of voltage () is directly proportional to the gradient in temperature ():
where is a temperature-dependent material property known as the Seebeck coefficient.
The standard measurement configuration shown in the figure shows four temperature regions and thus four voltage contributions:
# Change from to , in the lower copper wire.
# Change from to , in the alumel wire.
# Change from to , in the chromel wire.
# Change from to , in the upper copper wire.
The first and fourth contributions cancel out exactly, because these regions involve the same temperature change and an identical material.
As a result, does not influence the measured voltage.
The second and third contributions do not cancel, as they involve different materials.
The measured voltage turns out to be
where and are the Seebeck coefficients of the conductors attached to the positive and negative terminals of the voltmeter, respectively (chromel and alumel in the figure). | 0 | Metallurgy |
Bronze disease is the chloride corrosion of cuprous (copper-based) artifacts. It was originally thought to be caused by bacteria. It is contagious in that the chlorides which cause it can spread the condition if they are brought into contact with another cuprous object. Despite its name, bronze disease can affect any copper-bearing alloy, not just bronze. It is not reserved for antique objects but can affect contemporary metals like modern cupro-nickel coins.
Bronze disease ranges from vivid green to pastel green. It is commonly present in all colors in this range due to the series of reactions that cause it and there may also be tiny, possibly microscopic, blue crystals. Bronze disease typically affects isolated patches of the object in severe cases being a visibly and tactilely raised bloom of microscopic crystals as well as being associated with pitting. The patches of bronze disease can be scraped off the surface using a fingernail or a wooden pick. These properties are all in comparison with verdigris, which is normally a duller shade, uniform across the whole of the affected object, and cannot be scratched off with wood or fingernails. Unlike bronze disease, verdigris serves to protect the metal.
As it relies upon the presence of chlorides, water, and oxygen, the absence of one of these three halts the progress, although any damage done is irreversible. Treatment for the condition typically involves physical removal of the chlorides (through scrubbing), chemical or electrochemical removal, and then isolating the object from oxygen, water, and future chloride contamination using an airtight container or a wax coating. These treatments may also remove any patina, loss of which is often seen as undesirable to collectors and conservators but is preferable to loss of the object.
Bronze disease is common or even ubiquitous on artefacts recovered from a marine environment due to the presence of chlorides in seawater. Coastal areas may also be hazardous due to salt carried in the atmosphere as well as the humidity. Absence of dissolved chlorides and oxygen in the soil means buried objects may not be affected while interred (similarly, lack of soluble salts and oxygen means that buried metals may not develop a patina or that oxidation of the metal may be reversed). When an artefact is recovered, surface encrustations may hide and/or protect bronze disease.
Chlorides may occur in or on the metal due to contamination from soil, water (especially seawater), the atmosphere, human sweat, or be present as impurities when the object was created. In many cases chlorides may be present within the interior of the artefact; the disease may reoccur if not isolated from water and/or oxygen. | 0 | Metallurgy |
The rate of hormone biosynthesis and secretion is often regulated by a homeostatic negative feedback control mechanism. Such a mechanism depends on factors that influence the metabolism and excretion of hormones. Thus, higher hormone concentration alone cannot trigger the negative feedback mechanism. Negative feedback must be triggered by overproduction of an "effect" of the hormone.
Hormone secretion can be stimulated and inhibited by:
* Other hormones (stimulating- or releasing -hormones)
* Plasma concentrations of ions or nutrients, as well as binding globulins
* Neurons and mental activity
* Environmental changes, e.g., of light or temperature
One special group of hormones is the tropic hormones that stimulate the hormone production of other endocrine glands. For example, thyroid-stimulating hormone (TSH) causes growth and increased activity of another endocrine gland, the thyroid, which increases output of thyroid hormones.
To release active hormones quickly into the circulation, hormone biosynthetic cells may produce and store biologically inactive hormones in the form of pre- or prohormones. These can then be quickly converted into their active hormone form in response to a particular stimulus.
Eicosanoids are considered to act as local hormones. They are considered to be "local" because they possess specific effects on target cells close to their site of formation. They also have a rapid degradation cycle, making sure they do not reach distant sites within the body.
Hormones are also regulated by receptor agonists. Hormones are ligands, which are any kinds of molecules that produce a signal by binding to a receptor site on a protein. Hormone effects can be inhibited, thus regulated, by competing ligands that bind to the same target receptor as the hormone in question. When a competing ligand is bound to the receptor site, the hormone is unable to bind to that site and is unable to elicit a response from the target cell. These competing ligands are called antagonists of the hormone. | 1 | Gene expression + Signal Transduction |
Functional selectivity (or “agonist trafficking”, “biased agonism”, “biased signaling”, "ligand bias" and “differential engagement”) is the ligand-dependent selectivity for certain signal transduction pathways relative to a reference ligand (often the endogenous hormone or peptide) at the same receptor. Functional selectivity can be present when a receptor has several possible signal transduction pathways. To which degree each pathway is activated thus depends on which ligand binds to the receptor. Functional selectivity, or biased signaling, is most extensively characterized at G protein coupled receptors (GPCRs). A number of biased agonists, such as those at muscarinic M2 receptors tested as analgesics or antiproliferative drugs, or those at opioid receptors that mediate pain, show potential at various receptor families to increase beneficial properties while reducing side effects. For example, pre-clinical studies with G protein biased agonists at the μ-opioid receptor show equivalent efficacy for treating pain with reduced risk for addictive potential and respiratory depression. Studies within the chemokine receptor system also suggest that GPCR biased agonism is physiologically relevant. For example, a beta-arrestin biased agonist of the chemokine receptor CXCR3 induced greater chemotaxis of T cells relative to a G protein biased agonist. | 1 | Gene expression + Signal Transduction |
Standard reduction potentials in aqueous solution are also a useful way of predicting the non-aqueous chemistry of the metals involved. Thus, metals with high negative potentials, such as sodium, or potassium, will ignite in air, forming the respective oxides. These fires cannot be extinguished with water, which also react with the metals involved to give hydrogen, which is itself explosive. Noble metals, in contrast, are disinclined to react with oxygen and, for that reason (as well as their scarcity) have been valued for millennia, and used in jewellery and coins.
The adjacent table lists standard reduction potential in volts; electronegativity (revised Pauling); and electron affinity values (kJ/mol), for some metals and metalloids.
The simplified entries in the reaction column can be read in detail from the Pourbaix diagrams of the considered element in water. Noble metals have large positive potentials; elements not in this table have a negative standard potential or are not metals.
Electronegativity is included since it is reckoned to be, "a major driver of metal nobleness and reactivity".
On account of their high electron affinity values, the incorporation of a noble metal in the electrochemical photolysis process, such as platinum and gold, among others, can increase photoactivity.
Arsenic and antimony are usually considered to be metalloids rather than noble metals. However, physically speaking their most stable allotropes are metallic. Semiconductors, such as selenium and tellurium, have been excluded.
The black tarnish commonly seen on silver arises from its sensitivity to hydrogen sulfide:
:2 Ag + HS + O → AgS + HO.
Rayner-Canham contends that, "silver is so much more chemically-reactive and has such a different chemistry, that it should not be considered as a noble metal." In dentistry, silver is not regarded as a noble metal due to its tendency to corrode in the oral environment.
The relevance of the entry for water is addressed by Li et al. in the context of galvanic corrosion. Such a process will only occur when:
:"(1) two metals which have different electrochemical potentials are...connected, (2) an aqueous phase with electrolyte exists, and (3) one of the two metals has...potential lower than the potential of the reaction ( + 4e + = 4 OH</sup>)."
The superheavy elements from hassium (element 108) to livermorium (116) inclusive are expected to be "partially very noble metals"; chemical investigations of hassium has established that it behaves like its lighter congener osmium, and preliminary investigations of nihonium and flerovium have suggested but not definitively established noble behavior. Copernicium's behaviour seems to partly resemble both its lighter congener mercury and the noble gas radon. | 0 | Metallurgy |
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily related proteins that are cell surface receptors that detect molecules outside the cell and activate cellular responses. They are coupled with G proteins. They pass through the cell membrane seven times in the form of six loops (three extracellular loops interacting with ligand molecules, three intracellular loops interacting with G proteins, an N-terminal extracellular region and a C-terminal intracellular region) of amino acid residues, which is why they are sometimes referred to as seven-transmembrane receptors. Ligands can bind either to the extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site within transmembrane helices (rhodopsin-like family). They are all activated by agonists, although a spontaneous auto-activation of an empty receptor has also been observed.
G protein-coupled receptors are found only in eukaryotes, including yeast, and choanoflagellates. The ligands that bind and activate these receptors include light-sensitive compounds, odors, pheromones, hormones, and neurotransmitters, and vary in size from small molecules to peptides to large proteins. G protein-coupled receptors are involved in many diseases.
There are two principal signal transduction pathways involving the G protein-coupled receptors:
*the cAMP signal pathway and
*the phosphatidylinositol signal pathway.
When a ligand binds to the GPCR it causes a conformational change in the GPCR, which allows it to act as a guanine nucleotide exchange factor (GEF). The GPCR can then activate an associated G protein by exchanging the GDP bound to the G protein for a GTP. The G protein's α subunit, together with the bound GTP, can then dissociate from the β and γ subunits to further affect intracellular signaling proteins or target functional proteins directly depending on the α subunit type (G, G, G, G).
GPCRs are an important drug target and approximately 34% of all Food and Drug Administration (FDA) approved drugs target 108 members of this family. The global sales volume for these drugs is estimated to be 180 billion US dollars . It is estimated that GPCRs are targets for about 50% of drugs currently on the market, mainly due to their involvement in signaling pathways related to many diseases i.e. mental, metabolic including endocrinological disorders, immunological including viral infections, cardiovascular, inflammatory, senses disorders, and cancer. The long ago discovered association between GPCRs and many endogenous and exogenous substances, resulting in e.g. analgesia, is another dynamically developing field of the pharmaceutical research. | 1 | Gene expression + Signal Transduction |
Loam molding has been used to produce large symmetrical objects such as cannon and church bells. Loam is a mixture of clay and sand with straw or dung. A model of the produced is formed in a friable material (the chemise). The mold is formed around this chemise by covering it with loam. This is then baked (fired) and the chemise removed. The mold is then stood upright in a pit in front of the furnace for the molten metal to be poured. Afterwards the mold is broken off. Molds can thus only be used once, so that other methods are preferred for most purposes. | 0 | Metallurgy |
Metallurgy only appears in Mesoamerica in 800 CE with the best evidence from West Mexico. Much like in South America, fine metals were seen as a material for the elite. Metal's special qualities of colour and resonance seemed to have appealed most and then led to the particular technological developments seen in the region.
Exchange of ideas and goods with peoples from the Ecuador and Colombia region (likely via a maritime route) seems to have fueled early interest and development. Similar metal artifact types are found in West Mexico and the two regions: copper rings, needles, and tweezers being fabricated in the same ways as in Ecuador and also found in similar archaeological contexts. A multitude of bells were also found, but in this case they were cast using the same lost-wax casting method as seen in Colombia. During this period, copper was being used almost exclusively.
Continual contact kept the flow of ideas from that same region and later, coinciding with the development of Andean long distance maritime trade, influence from further south seems to have reached the region and led to a second period (1200–1300 CE to the Spanish arrival). By this time, copper alloys were being explored by West Mexican metallurgists, partly because the different mechanical properties were needed to fashion specific artifacts, particularly axe-monies – further evidence for contact with the Andean region. However, in general the new properties such alloys introduced were developed to meet regional needs, especially wirework bells, which at times had such high tin content in the bronze that it was irrelevant for its mechanical properties but gave the bells a golden colour.
The actual artifacts and then techniques were imported from the south, but west Mexican metallurgists worked ores from the abundant local deposits; the metal was not being imported. Even when the technology spread from West into north-eastern, central and southern Mexico, artifacts that can be traced back to West Mexican ores are abundant, if not exclusive. It is not always clear if the metal reached its final destination as an ingot, an ore or a finished artifact. Provenance studies on metal artifacts from southern Mesoamerica cast with the lost wax technique and dissimilar to west Mexican artifacts have shown that there might have been a second point of emergence of metallurgy into Mesoamerica there since no known source could be identified.
In the Tarascan Empire, copper and bronze was used for chisels, punches, awls, tweezers, needles, axes, discs, and breastplates.
The Aztecs did not initially adopt metal working, even though they had acquired metal objects from other peoples. However, as conquest gained them metal working regions, the technology started to spread. By the time of the Spanish conquest, a bronze-smelting technology had already been developed. Spanish conquistadors used indigenous smelting technology to produce weapons and tools. | 0 | Metallurgy |
The effects of calcium on human cells are specific, meaning that different types of cells respond in different ways. However, in certain circumstances, its action may be more general. Ca ions are one of the most widespread second messengers used in signal transduction. They make their entrance into the cytoplasm either from outside the cell through the cell membrane via calcium channels (such as calcium-binding proteins or voltage-gated calcium channels), or from some internal calcium storages such as the endoplasmic reticulum and mitochondria. Levels of intracellular calcium are regulated by transport proteins that remove it from the cell. For example, the sodium-calcium exchanger uses energy from the electrochemical gradient of sodium by coupling the influx of sodium into cell (and down its concentration gradient) with the transport of calcium out of the cell. In addition, the plasma membrane Ca ATPase (PMCA) obtains energy to pump calcium out of the cell by hydrolysing adenosine triphosphate (ATP). In neurons, voltage-dependent, calcium-selective ion channels are important for synaptic transmission through the release of neurotransmitters into the synaptic cleft by vesicle fusion of synaptic vesicles.
Calcium's function in muscle contraction was found as early as 1882 by Ringer. Subsequent investigations were to reveal its role as a messenger about a century later. Because its action is interconnected with cAMP, they are called synarchic messengers. Calcium can bind to several different calcium-modulated proteins such as troponin-C (the first one to be identified) and calmodulin, proteins that are necessary for promoting contraction in muscle.
In the endothelial cells which line the inside of blood vessels, Ca ions can regulate several signaling pathways which cause the smooth muscle surrounding blood vessels to relax. Some of these Ca-activated pathways include the stimulation of eNOS to produce nitric oxide, as well as the stimulation of K channels to efflux K and cause hyperpolarization of the cell membrane. Both nitric oxide and hyperpolarization cause the smooth muscle to relax in order to regulate the amount of tone in blood vessels. However, dysfunction within these Ca-activated pathways can lead to an increase in tone caused by unregulated smooth muscle contraction. This type of dysfunction can be seen in cardiovascular diseases, hypertension, and diabetes.
Calcium coordination plays an important role in defining the structure and function of proteins. An example a protein with calcium coordination is von Willebrand factor (vWF) which has an essential role in blood clot formation process. It was discovered using single molecule optical tweezers measurement that calcium-bound vWF acts as a shear force sensor in the blood. Shear force leads to unfolding of the A2 domain of vWF whose refolding rate is dramatically enhanced in the presence of calcium. | 1 | Gene expression + Signal Transduction |
As with many other places in Britain, there have been speculative articles written that connect Ariconium to the characters in Arthurian tales. Some are careful with their wording and state that they are not asserting historical facts; others are less careful and propagate fiction in the guise of hypothesis.
There are occasional mentions of Ariconium in poetic works, but there is nothing to connect them with the Ariconium of this article. They may be references to Kenchester at a time when Camden placed the site there, or to a similar-sounding word such as Uriconium, or to some other place or person; or as works of poetry, they may refer to nothing in particular at all. | 0 | Metallurgy |
* Coordinates the activities of more than 70 polypeptides required for initiation of transcription by RNA polymerase II
* Binds to the core promoter to position the polymerase properly
* Serves as the scaffold for assembly of the remainder of the transcription complex
* Acts as a channel for regulatory signals | 1 | Gene expression + Signal Transduction |
Jun 1943. Further report on the use of aged chromate baths to specification DTD 911, Bath iii (30 minute hot chromate bath). Petch M K. RAE MR7147(A). Met/RTN/22
Feb 1944. Variations in corrosion properties over magnesium alloy sheet. Jones E R W Petch M K. RAE MR6858. Met/RTN/21, also in J. Inst. Metals, Nov. I946
Feb 1944. Protection of magnesium alloy sheet to specification DTD 118 by a modified form of the I.G. acid dip (bath iv of specification.DTD 911). Petch M K. RAE MR7588. Met/RTN/23
Mar 1944. Protection of magnesium alloys against corrosion by electrolytic chromate films. Petch M K. RAE MR3726(D). Met/RTN/17
Nov 1944. The protection of magnesium alloy components against corrosion by sprayed coatings of "Thickal" Latex. Petch M K. RAE MR7290. Met/RTN/22
1949. Some Observations on the Behaviour of Platinum/Platinum-Rhodium Thermocouples at High Temperatures. M K McQuillan. Journal of Scientific Instruments, Volume 26, Number 10
1956. Titanium - Metallurgy of the Rarer Metals – 4. by McQuillan MK.; Publisher: London, Butterworths, 1956.
1956. Titanium. McQuillan, A. D.; McQuillan, M. K.; Castle, J. G.Physics Today, vol. 9, issue 10, p. 24. Publication Date: 00/1956
1956. Titanium. Alan Dennis McQuillan; Marion Katharine McQuillan. Publisher: New York : Academic Press ; London : Butterworths Scientific Publications, 1956.
1957. Titanium. Alan D MacQuillan; Marion Katharine Macquillan. Publisher: London Butterworth [1957]
1958. Titan. Alan Denis McQuillan; Marion Katharine McQuillan; Sergej Georgievič Glazunov; Leonid Pavlovič Lužnikov.Language: Russian . Publisher: Moskva : Gosudarstvennoe Naučno-Tehničeskoe Izdatel'stvo Literatury po Černoj i Cvetnoj Metallurgii, 1958.
1978. McQuillan, Marion. Graduate Engineers in Production. Cranfield Inst of Tech, 1978.
1979. Graduate myth. Production Engineer (Volume: 58 , Issue: 4 , April 1979 ) | 0 | Metallurgy |
Secondary sulfides—those formed by supergene secondary enrichment—are resistant (refractory) to sulfuric leaching. Secondary copper sulfides are dominated by the mineral chalcocite; a mineral formed from primary sulfides, like chalcopyrite, that undergo chemical processes such as oxidation or reduction. Typically, secondary sulfide ores are concentrated using froth flotation. Other extraction processes like leaching are effectively used for the extraction of secondary copper sulfides, but as demand for copper rises, extraction processes tailored for low-grade ores are required, due to the depletion of copper resources. Processes including in situ, dump, and heap leaching are cost-effective methods that are suitable for extracting copper from low-grade ores.
Extraction processes for secondary copper sulfides and low-grade ores includes the process of heap bioleaching. Heap bioleaching presents a cost efficient extraction method that requires a less intensive energy input resulting in a higher profit. This extraction process can be applied to large quantities of low-grade ores, at a lower capital cost with minimal environmental impact.
Generally, direct froth flotation is not used to concentrate copper oxide ores, as a result of the largely ionic and hydrophilic structure of the copper oxide mineral surface. Copper oxide ores are typically treated via chelating-reagent flotation and fatty-acid flotation, which use organic reagents to ensure adsorption onto the mineral surface through the formation of hydrophobic compounds on the mineral surface.
Some supergene sulfide deposits can be leached using a bacterial oxidation heap leach process to oxidize the sulfides to sulfuric acid, which also allows for simultaneous leaching with sulfuric acid to produce a copper sulfate solution. For oxide ores, solvent extraction and electrowinning technologies are used to recover the copper from the pregnant leach solution. To ensure the best recovery of copper, it is important to acknowledge the effect copper dissolution, acid consumption, and gangue mineral composition has on the efficacy of extraction.
Supergene sulfide ores rich in native copper are refractory to treatment with sulfuric acid leaching on all practicable time scales, and the dense metal particles do not react with froth flotation media. Typically, if native copper is a minor part of a supergene profile it will not be recovered and will report to the tailings. When rich enough, native copper ore bodies may be treated to recover the contained copper by gravity separation. Often, the nature of the gangue is important, as clay-rich native copper ores prove difficult to liberate. This is because clay minerals interact with flotation reagents used in extraction processes, that are then consumed, which results in minimal recovery of a high grade copper concentrate. | 0 | Metallurgy |