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In the canonical pathway, Wnt proteins binds to its transmembrane receptor of the Frizzled family of proteins. The binding of Wnt to a Frizzled protein activates the Dishevelled protein. In its active state the Dishevelled protein inhibits the activity of the glycogen synthase kinase 3 (GSK3) enzyme. Normally active GSK3 prevents the dissociation of β-catenin to the APC protein, which results in β-catenin degradation. Thus inhibited GSK3, allows β-catenin to dissociate from APC, accumulate, and travel to nucleus. In the nucleus β-catenin associates with Lef/Tcf transcription factor, which is already working on DNA as a repressor, inhibiting the transcription of the genes it binds. Binding of β-catenin to Lef/Tcf works as a transcription activator, activating the transcription of the Wnt-responsive genes. | 1 | Gene expression + Signal Transduction |
SIN3B has been shown to interact with HDAC1, Zinc finger and BTB domain-containing protein 16, SUDS3 and IKZF1. | 1 | Gene expression + Signal Transduction |
Some assembly methods also make use of type IIs restriction endonucleases. These differ from other type II endonucleases as they cut several base pairs away from the recognition site. As a result, the overhang sequence can be modified to contain the desired sequence. This provides Type IIs assembly methods with two advantages – it enables "scar-less" assembly, and allows for one-pot, multi-part assembly. Assembly methods that use type IIs endonucleases include Golden Gate and its associated variants. | 1 | Gene expression + Signal Transduction |
RECODE is a database of "programmed" frameshifts, bypassing and codon redefinition used for gene expression. | 1 | Gene expression + Signal Transduction |
Fluxes are materials added to the ore during smelting to catalyze the desired reactions and to chemically bind to unwanted impurities or reaction products. Calcium carbonate or calcium oxide in the form of lime are often used for this purpose, since they react with sulfur, phosphorus, and silicon impurities to allow them to be readily separated and discarded, in the form of slag. Fluxes may also serve to control the viscosity and neutralize unwanted acids.
Flux and slag can provide a secondary service after the reduction step is complete; they provide a molten cover on the purified metal, preventing contact with oxygen while still hot enough to readily oxidize. This prevents impurities from forming in the metal. | 0 | Metallurgy |
In common use, the research definition, including post-transition metals and metalloids, is extended to include compounds such as cementite, FeC. These compounds, sometimes termed interstitial compounds, can be stoichiometric, and share similar properties to the intermetallic compounds defined above. | 0 | Metallurgy |
Activated GPCRs cause a conformational change in the attached G protein complex, which results in the G alpha subunit's exchanging GDP for GTP and separation from the beta and gamma subunits. The G alpha subunit, in turn, activates adenylyl cyclase, which quickly converts ATP into cAMP. This leads to the activation of the cAMP-dependent pathway. This pathway can also be activated downstream by directly activating adenylyl cyclase or PKA.
Molecules that activate cAMP pathway include:
* cholera toxin - increases cAMP levels
* forskolin - a diterpene natural product that activates adenylyl cyclase
* caffeine and theophylline inhibit cAMP phosphodiesterase, which degrades cAMP - thus enabling higher levels of cAMP than would otherwise be had.
* bucladesine (dibutyryl cAMP, db cAMP) - also a phosphodiesterase inhibitor
* pertussis toxin, which increases cAMP levels by inhibiting Gi to its GDP (inactive) form. This leads to an increase in adenylyl cyclase activity, thereby increasing cAMP levels, which can lead to an increase in insulin and therefore hypoglycemia | 1 | Gene expression + Signal Transduction |
While all the metals of antiquity but tin and lead occur natively, only gold and silver are commonly found as the native metal.
* Gold and silver occur frequently in their native form
* Mercury compounds are reduced to elemental mercury simply by low-temperature heating (500 °C).
* Tin and iron occur as oxides and can be reduced with carbon monoxide (produced by, for example, burning charcoal) at 900 °C.
* Copper and lead compounds can be roasted to produce the oxides, which are then reduced with carbon monoxide at 900 °C.
* Meteoric iron is often found as the native metal and it was the earliest source for iron objects known to humanity | 0 | Metallurgy |
Due to the fact that translation elongation is an irreversible process, there are few known mechanisms of its regulation. However, it has been shown that translational efficiency is reduced via diminished tRNA pools, which are required for the elongation of polypeptides. In fact, the richness of these tRNA pools are susceptible to change through cellular oxygen supply. | 1 | Gene expression + Signal Transduction |
In coal-fired processes, part of the fuel is first burnt to heat the charge. The product of this combustion is CO. When the temperature reaches 1,000 °C, the CO reacts with the unburned carbon to create CO:
The production of H cannot be achieved by the thermal decomposition of water, as the temperatures involved are too low. Hydrogen is in fact produced along with carbon monoxide by the reaction:
These two reducing gas production reactions, which consume 172.45 and 131.4 kJ/mol respectively, are highly endothermic and operate by limiting charge heating. | 0 | Metallurgy |
The process of elongation is the synthesis of a copy of the DNA into messenger RNA. RNA Pol II matches complementary RNA nucleotides to the template DNA by Watson-Crick base pairing. These RNA nucleotides are ligated, resulting in a strand of messenger RNA.
Unlike DNA replication, mRNA transcription can involve multiple RNA polymerases on a single DNA template and multiple rounds of transcription (amplification of particular mRNA), so many mRNA molecules can be rapidly produced from a single copy of a gene.
Elongation also involves a proofreading mechanism that can replace incorrectly incorporated bases. In eukaryotes, this may correspond with short pauses during transcription that allow appropriate RNA editing factors to bind. These pauses may be intrinsic to the RNA polymerase or due to chromatin structure. | 1 | Gene expression + Signal Transduction |
Understanding the interfacial energy of materials with different types of interphase boundaries (IPBs) provides valuable insights into several aspects of their behavior, including thermodynamic stability, deformation behavior, and phase evolution. | 0 | Metallurgy |
DBTSS, the DataBase of Transcriptional Start Sites, is a database hosted by the Human Genome Center at the University of Tokyo. It contains the exact positions of transcriptional start sites in the genomes of various organisms. | 1 | Gene expression + Signal Transduction |
When the cost of producing slaves became too high to justify slave labourers for the many mines throughout the empire around the second century, a system of indentured servitude was introduced for convicts. In 369 AD, a law was reinstated due to the closure of many deep mines; the emperor Hadrian had previously given the control of mines to private employers, so that workers were hired rather than working out of force. Through the institution of this system profits increased (Shepard 1993). In the case of Noricum, there is archaeological evidence of freemen labour in the metal trade and extraction through graffiti on mine walls. In this province, many men were given Roman citizenship for their efforts contributing to the procurement of metal for the empire. Both privately owned and government run mines were in operation simultaneously (Shepard 1993). | 0 | Metallurgy |
Replication, in metallography, is the use of thin plastic films to nondestructively duplicate the microstructure of a component. The film is then examined at high magnifications.
Replication is a method of copying the topography of a surface by casting or impressing material onto the surface. It is the commonly used technique to duplicate surfaces that are inaccessible in metrology to other forms of nondestructive testing. Replicas can be used in biology as well:
The replicas may be imaged in the light microscope or coated with heavy metals, the replicating film melted away, and the heavy metal replica imaged in a Transmission Electron Microscope (TEM).
The same materials, cellulose acetate films, are used for creating replicas of biological materials such as bacteria.
Field Metallurgical Replication (FMR), in field metallography, is the use of metallurgical preparation on surfaces in the field, by polishing to a mirror image, along with application of acetate or other thin plastic films designed to nondestructively duplicate the microstructure of a part or structure in-situ. The FMR replica is then transferred to a glass slide for examination by optical microscopy, electron microscopy, and other methods. | 0 | Metallurgy |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), Valine (Val, V) | 1 | Gene expression + Signal Transduction |
When a shape-memory alloy is in its cold state (below M), the metal can be bent or stretched and will hold those shapes until heated above the transition temperature. Upon heating, the shape changes to its original. When the metal cools again, it will retain the shape, until deformed again.
With the one-way effect, cooling from high temperatures does not cause a macroscopic shape change. A deformation is necessary to create the low-temperature shape. On heating, transformation starts at A and is completed at A (typically 2 to 20 °C or hotter, depending on the alloy or the loading conditions). A is determined by the alloy type and composition and can vary between and . | 0 | Metallurgy |
In an Arabidopsis thaliana study, hundreds of different proteins demonstrated the possibility to bind to CaM in plants. | 1 | Gene expression + Signal Transduction |
Plano-convex ingots are lumps of metal with a flat or slightly concave top and a convex base. They are sometimes, misleadingly, referred to as bun ingots which imply the opposite concavity. They are most often made of copper, although other materials such as copper alloy, lead and tin are used. The first examples known were from the Near East during the 3rd and 2nd Millennia BC. By the end of the Bronze Age they were found throughout Europe and in Western and South Asia. Similar ingot forms continued in use during later Roman and Medieval periods. | 0 | Metallurgy |
In humans, the protein is encoded by the RB1 gene located on chromosome 13—more specifically, 13q14.1-q14.2. If both alleles of this gene are mutated in a retinal cell, the protein is inactivated and the cells grow uncontrollably, resulting in development of retinoblastoma cancer, hence the "RB" in the name pRb. Thus most pRb knock-outs occur in retinal tissue when UV radiation-induced mutation inactivates all healthy copies of the gene, but pRb knock-out has also been documented in certain skin cancers in patients from New Zealand where the amount of UV radiation is significantly higher.
Two forms of retinoblastoma were noticed: a bilateral, familial form and a unilateral, sporadic form. Sufferers of the former were over six times more likely to develop other types of cancer later in life, compared to individuals with sporadic retinoblastoma. This highlighted the fact that mutated pRb could be inherited and lent support for the two-hit hypothesis. This states that only one working allele of a tumour suppressor gene is necessary for its function (the mutated gene is recessive), and so both need to be mutated before the cancer phenotype will appear. In the familial form, a mutated allele is inherited along with a normal allele. In this case, should a cell sustain only one mutation in the other RB gene, all pRb in that cell would be ineffective at inhibiting cell cycle progression, allowing cells to divide uncontrollably and eventually become cancerous. Furthermore, as one allele is already mutated in all other somatic cells, the future incidence of cancers in these individuals is observed with linear kinetics. The working allele need not undergo a mutation per se, as loss of heterozygosity (LOH) is frequently observed in such tumours.
However, in the sporadic form, both alleles would need to sustain a mutation before the cell can become cancerous. This explains why sufferers of sporadic retinoblastoma are not at increased risk of cancers later in life, as both alleles are functional in all their other cells. Future cancer incidence in sporadic pRb cases is observed with polynomial kinetics, not exactly quadratic as expected because the first mutation must arise through normal mechanisms, and then can be duplicated by LOH to result in a tumour progenitor.
RB1 orthologs have also been identified in most mammals for which complete genome data are available.
RB/E2F-family proteins repress transcription. | 1 | Gene expression + Signal Transduction |
Unlike LPB, traditional burnishing tools consist of a hard wheel or fixed lubricated ball pressed into the surface of an asymmetrical work piece with sufficient force to deform the surface layers, usually in a lathe. The process does multiple passes over the work pieces, usually under increasing load, to improve surface finish and deliberately cold work the surface. Roller and ball burnishing have been studied in Russia and Japan, and were applied most extensively in the USSR in the 1970s. Various burnishing methods are used, particularly in Eastern Europe, to improve fatigue life. Improvements in HCF, corrosion fatigue and SCC are documented, with fatigue strength enhancement attributed to improved finish, the development of a compressive surface layer, and the increased yield strength of the cold worked surface.
LPB was developed and patented by Lambda Technologies in Cincinnati, Ohio in 1996. Since then, LPB has been developed to produce compression in a wide array of materials to mitigate surface damage, including fretting, corrosion pitting, stress corrosion cracking (SCC), and foreign object damage (FOD), and is being employed to aid in daily MRO operations. To this day, LPB is the only metal improvement method applied under continuous closed-loop process control and has been successfully applied to turbine engines, piston engines, propellers, aging aircraft structures, landing gear, nuclear waste material containers, biomedical implants, armaments, fitness equipment and welded joints. The applications involved titanium, iron, nickel and steel-based components and showed improved damage tolerance as well as high and low cycle fatigue performance by an order of magnitude. | 0 | Metallurgy |
In bacteria, the same enzyme catalyzes the synthesis of mRNA and non-coding RNA (ncRNA).
RNAP is a large molecule. The core enzyme has five subunits (~400 kDa):
; β′: The β′ subunit is the largest subunit, and is encoded by the rpoC gene. The β′ subunit contains part of the active center responsible for RNA synthesis and contains some of the determinants for non-sequence-specific interactions with DNA and nascent RNA. It is split into two subunits in Cyanobacteria and chloroplasts.
; β: The β subunit is the second-largest subunit, and is encoded by the rpoB gene. The β subunit contains the rest of the active center responsible for RNA synthesis and contains the rest of the determinants for non-sequence-specific interactions with DNA and nascent RNA.
; α (α and α): Two copies of the α subunit, being the third-largest subunit, are present in a molecule of RNAP: α and α (one and two). Each α subunit contains two domains: αNTD (N-terminal domain) and αCTD (C-terminal domain). αNTD contains determinants for assembly of RNAP. αCTD (C-terminal domain) contains determinants for interaction with promoter DNA, making non-sequence-non-specific interactions at most promoters and sequence-specific interactions at upstream-element-containing promoters, and contains determinants for interactions with regulatory factors.
; ω: The ω subunit is the smallest subunit. The ω subunit facilitates assembly of RNAP and stabilizes assembled RNAP.
In order to bind promoters, RNAP core associates with the transcription initiation factor sigma (σ) to form RNA polymerase holoenzyme. Sigma reduces the affinity of RNAP for nonspecific DNA while increasing specificity for promoters, allowing transcription to initiate at correct sites. The complete holoenzyme therefore has 6 subunits: β′βα and αωσ (~450 kDa). | 1 | Gene expression + Signal Transduction |
Suppose an alloy at an equilibrium temperature T consists of mass fraction of element B. Suppose also that at temperature T the alloy consists of two phases, α and β, for which the α consists of , and β consists of . Let the mass of the α phase in the alloy be so that the mass of the β phase is , where is the total mass of the alloy.
By definition, then, the mass of element B in the α phase is , while the mass of element B in the β phase is . Together these two quantities sum to the total mass of element B in the alloy, which is given by . Therefore,
By rearranging, one finds that
This final fraction is the mass fraction of the α phase in the alloy. | 0 | Metallurgy |
The sigma-2 receptor is expressed in brain and retinal cells where it regulates key pathways involved in age-related diseases such as Alzheimers disease and synucleinopathies such as Parkinsons disease and dementia with Lewy bodies, as well as dry age-related macular degeneration (dry AMD). The normal activity of processes regulated by sigma-2, such as protein trafficking and autophagy, is impaired by cellular stresses such as oxidative stress and the build-up of amyloid-β and α-synuclein oligomers. Studies support that sigma-2 modulators can rescue biological processes that are impaired in neurodegenerative diseases.
In vitro studies of experimental sigma-2 receptor modulators demonstrated an ability to prevent the binding of amyloid-β oligomers to neurons and also to displace bound amyloid-β oligomers from neuronal receptors. In addition, transgenic mice treated sigma-2 receptor modulators performed significantly better in the Morris water maze task than did vehicle-treated mice. Taken together, these studies suggest that sigma-2 receptor modulation may be a viable approach for treating certain neurodegenerative diseases of the CNS and retina. | 1 | Gene expression + Signal Transduction |
A transcriptome in vivo analysis tag (TIVA tag) is a multifunctional, photoactivatable mRNA-capture molecule designed for isolating mRNA from a single cell in complex tissues.
__TOC__ | 1 | Gene expression + Signal Transduction |
In this region, the dominant deformation mechanism is power law creep, such that the strain rate goes as the stress raised to a stress exponent n. This region is dominated by dislocation creep. The value of this stress exponent is dependent upon the material and the microstructure. If deformation is occurring by slip, n=1-8, and for grain boundary sliding n=2 or 4.
The general equation for power law creep is as follows, where <math>A_2
is the applied shear stress, and is the effective diffusion constant.
Within the power law creep region, there are two subsections corresponding to low temperature power law creep that is dominated by core controlled dislocation motion and high temperature power law creep that is controlled by diffusion in the lattice. Low temperature core diffusion, sometimes called pipe diffusion, occurs because dislocations are more quickly able to diffuse through the pipe-like core of a dislocation. The effective diffusion coefficient in the strain rate equation depends on whether or not the system is dominated by core diffusion or lattice diffusion and can be generalized as follows where is the volumetric lattice diffusion constant, is the area corresponding to the dislocation core, is the diffusion coefficient for the core, and b is the Burger's vector.
In the high temperature region, the effective diffusion constant is simply the volumetric lattice diffusion constant, whereas at low temperatures the diffusion constant is given by the expression . Thus in the high temperature power law creep region, the strain rate goes as , and in the low temperature power law creep region the strain rate goes as . | 0 | Metallurgy |
Disrupting pRb expression in vitro, either by gene deletion or knockdown of pRb short interfering RNA, causes dendrites to branch out farther. In addition, Schwann cells, which provide essential support for the survival of neurons, travel with the neurites, extending farther than normal. The inhibition of pRb supports the continued growth of nerve cells. | 1 | Gene expression + Signal Transduction |
A non-competitive antagonist is a type of insurmountable antagonist that may act in one of two ways: by binding to an allosteric site of the receptor, or by irreversibly binding to the active site of the receptor. The former meaning has been standardised by the IUPHAR, and is equivalent to the antagonist being called an allosteric antagonist. While the mechanism of antagonism is different in both of these phenomena, they are both called "non-competitive" because the end-results of each are functionally very similar. Unlike competitive antagonists, which affect the amount of agonist necessary to achieve a maximal response but do not affect the magnitude of that maximal response, non-competitive antagonists reduce the magnitude of the maximum response that can be attained by any amount of agonist. This property earns them the name "non-competitive" because their effects cannot be negated, no matter how much agonist is present. In functional assays of non-competitive antagonists, depression of the maximal response of agonist dose-response curves, and in some cases, rightward shifts, is produced. The rightward shift will occur as a result of a receptor reserve (also known as spare receptors) and inhibition of the agonist response will only occur when this reserve is depleted.
An antagonist that binds to the active site of a receptor is said to be "non-competitive" if the bond between the active site and the antagonist is irreversible or nearly so. This usage of the term "non-competitive" may not be ideal, however, since the term "irreversible competitive antagonism" may also be used to describe the same phenomenon without the potential for confusion with the second meaning of "non-competitive antagonism" discussed below.
The second form of "non-competitive antagonists" act at an allosteric site. These antagonists bind to a distinctly separate binding site from the agonist, exerting their action to that receptor via the other binding site. They do not compete with agonists for binding at the active site. The bound antagonists may prevent conformational changes in the receptor required for receptor activation after the agonist binds. Cyclothiazide has been shown to act as a reversible non-competitive antagonist of mGluR1 receptor. Another example of a non-competitive is phenoxybenzamine which binds irreversibly (with covalent bonds) to alpha-adrenergic receptors, which in turn reduces the fraction of available receptors and reduces the maximal effect that can be produced by the agonist. | 1 | Gene expression + Signal Transduction |
Bulat is a type of steel alloy known in Russia from medieval times; it was regularly mentioned in Russian legends as the material of choice for cold steel. The name булат is a Russian transliteration of the Persian word fulad, meaning steel. This type of steel was used by the armies of nomadic peoples. Bulat steel was the main type of steel used for swords in the armies of Genghis Khan. Bulat Steel is generally agreed to be a Russian name for wootz steel, the production method of which has been lost for centuries, and the bulat steel used today makes use of a more recently developed technique. | 0 | Metallurgy |
Various techniques are used in the investigative process of metallurgical failure analysis.
* Macroscopic examination: camera, stereoscope
* Microscopic examination: light microscopy, electron microscopy, x-ray microscopy, metallographic etching
* Mechanical testing: hardness testing, tensile testing, Charpy impact testing
* Chemical testing: microprobe analysis, energy dispersive spectroscopy
Non-destructive testing: Non-destructive testing is a test method that allows certain physical properties of metal to be examined without taking the samples completely out of service. NDT is generally used to detect failures in components before the component fails catastrophically.
Destructive testing: Destructive testing involves removing a metal component from service and sectioning the component for analysis. Destructive testing gives the failure analyst the ability to conduct the analysis in a laboratory setting and perform tests on the material that will ultimately destroy the component. | 0 | Metallurgy |
Founded as the American Institute of Mining Engineers (AIME), the institute had a membership at the beginning of 1915 of over 5,000, made up of honorary, elected, and associate members. The annual meeting of the institute was held in February, with other meetings during the year as authorized by the council. The institute published three volumes of Transactions annually and a monthly Bulletin which appeared on the first of each month. The headquarters of the institute was in the Engineering Building in New York City.
Following creation of the Petroleum Division in 1922, the Iron and Steel Division in 1928 and the Institute of Metals Division in 1933 the name of the society was changed in 1957 to the American Institute of Mining, Metallurgical and Petroleum Engineers. Three of the current member societies were then created from the divisions, increasing to four in 1974 when the Iron and Steel Society (ISS) was formed. In 2004 ISS merged with the Association of Iron and Steel Engineers (AISE) to form the Association for Iron and Steel Technology (AIST) whilst remaining a member society of AIME. | 0 | Metallurgy |
The touchstone method is most common by far and does not damage the item in question. A rubbing of the item is made on a special stone, treated with acids and the result is compared to the result of the same process done on a sample of gold with a known purity. Red radiolarian chert or black siliceous slate were used for this. Differences in precious metal content as small as 10 to 20 parts per thousand can often be established with confidence by the test, using acids and gold samples both of a specific, known concentration. | 0 | Metallurgy |
The practice of tin mining likely began circa 3000 B.C. in Western Asia, British Isles and Europe. Tin was an essential ingredient of bronze production during the Bronze Age.
The practice of tinning ironware to protect it against rust is an ancient one. This may have been the work of the whitesmith. This was done after the article was fabricated, whereas tinplate was tinned before fabrication. Tinplate was apparently produced in the 1620s at a mill of (or under the patronage of) the Earl of Southampton, but it is not clear how long this continued.
The first production of tinplate was probably in Bohemia, from where the trade spread to Saxony, and was well-established there by the 1660s. Andrew Yarranton and Ambrose Crowley (a Stourbridge blacksmith and father of the more famous Sir Ambrose) visited Dresden in 1667 and learned how it was made. In doing so, they were sponsored by various local ironmasters and people connected with the project to make the river Stour navigable. In Saxony, the plates were forged, but when they conducted experiments on their return to England, they tried rolling the iron. This led to the ironmasters Philip Foley and Joshua Newborough (two of the sponsors) in 1670 erecting a new mill, Wolverley Lower Mill (or forge) in Worcestershire. This contained three shops, one being a slitting mill (which would serve as a rolling mill), and the others were forges. In 1678 one of these was making frying pans and the other drawing out blooms made in finery forges elsewhere. It is likely that the intention was to roll the plates and then finish them under a hammer, but the plan was frustrated by William Chamberlaine renewing a patent granted to him and Dud Dudley in 1662.
The slitter at Wolverley was Thomas Cooke. Another Thomas Cooke, perhaps his son, moved to Pontypool and worked there for John Hanbury. He had a slitting mill there and was also producing iron plates called Pontpoole plates. Edward Lhuyd reported the existence of this mill in 1697. This has been claimed as a tinplate works, but it was almost certainly only producing (untinned) blackplate.
Tinplate first begins to appear in the Gloucester Port Books (which record trade passing through Gloucester), mostly from ports in the Bristol Channel in 1725. The tinplate was shipped from Newport, Monmouthshire. This immediately follows the first appearance (in French) of Reamurs Principes de lart de fer-blanc, and prior to a report of it being published in England.
Further mills followed a few years later, initially in many iron-making regions in England and Wales, but later mainly in south Wales, most notably the Melingriffith Tin Plate Works, Whitchurch, Cardiff, which was founded some time before 1750. In 1805, 80,000 boxes were made and 50,000 exported. The industry continued to grow until 1891. One of the greatest markets was the United States, but that market was cut off in 1891 when the McKinley tariff was enacted. This caused a great retrenchment in the British industry and the emigration to America of many of those were no longer employed in the surviving tinplate works.
Despite this blow, the industry continued, but on a smaller scale. There were 518 mills in operation in 1937, including 224 belonging to Richard Thomas & Co. The traditional pack mill had been overtaken by the improved strip mill, of which the first in Great Britain was built by Richard Thomas & Co. in the late 1930s. Strip mills rendered the old pack mills obsolete and the last of them closed circa the 1960s. | 0 | Metallurgy |
In mammals, the eIF4E•G•A trimeric complex can be directly purified from cells, while only the two subunit eIF4E•G can be purified from yeast cells. eIF4E binds the mG 5 cap and the eIF4G scaffold, connecting the mRNA 5 terminus to a hub of other initiation factors and mRNA. The interaction of eIF4G•A is thought to guide the formation of a single-stranded RNA landing pad for the 43S preinitiation complex (43S PIC) via eIF4A's RNA helicase activity.
The eIF4F proteins interact with a number of different binding partners, and there are multiple genetic isoforms of eIF4A, eIF4E, and eIF4G in the human genome. In mammals, eIF4F is bridged to the 40S ribosomal subunit by eIF3 via eIF4G, while budding yeast lacks this connection. Interactions between eIF4G and PABP are thought to mediate the circularization of mRNA particles.
Approximate molecular weight for human proteins.
In addition to the major proteins encompassing the eIF4F trimer, the eIF4F complex functionally interacts with proteins including eIF4B and eIF4H. The unusual isoform of eIF4G, eIF4G2 or DAP5, also appears to perform a non-canonical translation function. | 1 | Gene expression + Signal Transduction |
The compound's band structure exhibits a double Dirac cone, enabling Dirac fermions. A 30 meV gap separates the cones, which indicates the quantum Hall effect and massive Dirac fermions. Close measurement of the Fermi surface via the de Haas-van Alphen effect suggests that the massive fermions also exhibit Kane-Mele-type spin-orbit coupling.
FeSn can also host magnetic skyrmions, but these typically require high magnetic fields to nucleate. For samples with a small (but nonzero) thickness gradient, only a small-amplitude (5-10 mT), direction-variant magnetic field suffices to nucleate the quasiparticles. | 0 | Metallurgy |
The maintenance of heterochromatin regions by RITS complexes has been described as a self-reinforcing feedback loop, in which RITS complexes stably bind the methylated histones of a heterochromatin region using the Chp1 protein and induce co-transcriptional degradation of any nascent messenger RNA (mRNA) transcripts, which are then used as RNA-dependent RNA polymerase substrates to replenish the complement of siRNA molecules to form more RITS complexes. The RITS complex localizes to heterochromatic regions through the base pairing of the nascent heterochromatic transcripts as well as through the Chp chromodomain which recognizes methylated histones found in heterochromatin. Once incorporated into the heterochromatin, the RITS complex is also known to play a role in the recruitment of other RNAi complexes as well as other chromatin modifying enzymes to specific genomic regions. Heterochromatin formation, but possibly not maintenance, is dependent on the ribonuclease protein dicer, which is used to generate the initial complement of siRNAs. | 1 | Gene expression + Signal Transduction |
The first reported metallic glass was an alloy (AuSi) produced at Caltech by W. Klement (Jr.), Willens and Duwez in 1960. This and other early glass-forming alloys had to be cooled extremely rapidly (on the order of one megakelvin per second, 10 K/s) to avoid crystallization. An important consequence of this was that metallic glasses could only be produced in a limited number of forms (typically ribbons, foils, or wires) in which one dimension was small so that heat could be extracted quickly enough to achieve the necessary cooling rate. As a result, metallic glass specimens (with a few exceptions) were limited to thicknesses of less than one hundred micrometers.
In 1969, an alloy of 77.5% palladium, 6% copper, and 16.5% silicon was found to have critical cooling rate between 100 and 1000 K/s.
In 1976, H. Liebermann and C. Graham developed a new method of manufacturing thin ribbons of amorphous metal on a supercooled fast-spinning wheel. This was an alloy of iron, nickel, and boron. The material, known as Metglas, was commercialized in the early 1980s and is used for low-loss power distribution transformers (amorphous metal transformer). Metglas-2605 is composed of 80% iron and 20% boron, has a Curie temperature of and a room temperature saturation magnetization of 1.56 teslas.
In the early 1980s, glassy ingots with a diameter of were produced from the alloy of 55% palladium, 22.5% lead, and 22.5% antimony, by surface etching followed with heating-cooling cycles. Using boron oxide flux, the achievable thickness was increased to a centimeter.
In 1982, a study on amorphous metal structural relaxation indicated a relationship between the specific heat and temperature of (FeNi)P. As the material was heated up, the properties developed a negative relationship starting at 375 K, which was due to the change in relaxed amorphous states. When the material was annealed for periods from 1 to 48 hours , the properties developed a positive relationship starting at 475 K for all annealing periods, since the annealing induced structure disappears at that temperature. In this study, amorphous alloys demonstrated glass transition and a super cooled liquid region. Between 1988 and 1992, more studies found more glass-type alloys with glass transition and a super cooled liquid region. From those studies, bulk glass alloys were made of La, Mg, and Zr, and these alloys demonstrated plasticity even when their ribbon thickness was increased from 20 μm to 50 μm. The plasticity was a stark difference to past amorphous metals that became brittle at those thicknesses.
In 1988, alloys of lanthanum, aluminium, and copper ore were found to be highly glass-forming. Al-based metallic glasses containing Scandium exhibited a record-type tensile mechanical strength of about .
Before new techniques were found in 1990, bulk amorphous alloys of several millimeters in thickness were rare, except for a few exceptions, Pd-based amorphous alloys had been formed into rods with a diameter by quenching, and spheres with a diameter were formed by repetition flux melting with BO and quenching.
In the 1990s new alloys were developed that form glasses at cooling rates as low as one kelvin per second. These cooling rates can be achieved by simple casting into metallic molds. These "bulk" amorphous alloys can be cast into parts of up to several centimeters in thickness (the maximum thickness depending on the alloy) while retaining an amorphous structure. The best glass-forming alloys are based on zirconium and palladium, but alloys based on iron, titanium, copper, magnesium, and other metals are also known. Many amorphous alloys are formed by exploiting a phenomenon called the "confusion" effect. Such alloys contain so many different elements (often four or more) that upon cooling at sufficiently fast rates, the constituent atoms simply cannot coordinate themselves into the equilibrium crystalline state before their mobility is stopped. In this way, the random disordered state of the atoms is "locked in".
In 1992, the commercial amorphous alloy, Vitreloy 1 (41.2% Zr, 13.8% Ti, 12.5% Cu, 10% Ni, and 22.5% Be), was developed at Caltech, as a part of Department of Energy and NASA research of new aerospace materials.
By 2000, research in Tohoku University and Caltech yielded multicomponent alloys based on lanthanum, magnesium, zirconium, palladium, iron, copper, and titanium, with critical cooling rate between 1 K/s and 100 K/s, comparable to oxide glasses.
In 2004, bulk amorphous steel was successfully produced by two groups: one at Oak Ridge National Laboratory, who refers to their product as "glassy steel", and the other at the University of Virginia, calling theirs "DARVA-Glass 101". The product is non-magnetic at room temperature and significantly stronger than conventional steel, though a long research and development process remains before the introduction of the material into public or military use.
In 2018 a team at SLAC National Accelerator Laboratory, the National Institute of Standards and Technology (NIST) and Northwestern University reported the use of artificial intelligence to predict and evaluate samples of 20,000 different likely metallic glass alloys in a year. Their methods promise to speed up research and time to market for new amorphous metals alloys. | 0 | Metallurgy |
Due to the binding capabilities of antipsychotic drugs and various neurotransmitters associated with mood, the sigma-2 receptor is a viable target for therapies related to neuropsychiatric disorders and modulation of emotional response. It is thought to be involved in the pathophysiology of schizophrenia, and sigma-2 receptors have been shown to be less abundant in schizophrenic patients. Additionally, PCP, which is an NMDA antagonist, can induce schizophrenia, while sigma-2 receptor activation has been shown to antagonize effects of PCP, implying antipsychotic capabilities. Sigma receptors are a potential target for treatment of dystonia, given high densities in affected regions of the brain. Anti-ischemics ifenprodil and eliprodil, the binding of which increases blood flow, have also shown affinity to sigma receptors.
In experimental trials in mice and rats, the sigma-2 receptor ligand siramesine caused reduced anxiety and displayed antidepressant capabilities, while other studies have shown inhibition of selective sigma receptor radioligands by antidepressants, in the mouse and rat brain. | 1 | Gene expression + Signal Transduction |
When inactive, the PKA apoenzyme exists as a tetramer which consists of two regulatory subunits and two catalytic subunits. The catalytic subunit contains the active site, a series of canonical residues found in protein kinases that bind and hydrolyse ATP, and a domain to bind the regulatory subunit. The regulatory subunit has domains to bind to cyclic AMP, a domain that interacts with catalytic subunit, and an auto inhibitory domain. There are two major forms of regulatory subunit; RI and RII.
Mammalian cells have at least two types of PKAs: type I is mainly in the cytosol, whereas type II is bound via its regulatory subunits and special anchoring proteins, described in the anchorage section, to the plasma membrane, nuclear membrane, mitochondrial outer membrane, and microtubules. In both types, once the catalytic subunits are freed and active, they can migrate into the nucleus (where they can phosphorylate transcription regulatory proteins), while the regulatory subunits remain in the cytoplasm.
The following human genes encode PKA subunits:
* catalytic subunit – PRKACA, PRKACB, PRKACG
* regulatory subunit type I - PRKAR1A, PRKAR1B
* regulatory subunit type II - PRKAR2A, PRKAR2B | 1 | Gene expression + Signal Transduction |
SMAs display a phenomenon sometimes called superelasticity, but is more accurately described as pseudoelasticity. “Superelasticity” implies that the atomic bonds between atoms stretch to an extreme length without incurring plastic deformation. Pseudoelasticity still achieves large, recoverable strains with little to no permanent deformation, but it relies on more complex mechanisms.
SMAs exhibit at least 3 kinds of pseudoelasticty. The two less-studied kinds of pseudoelasticity are pseudo-twin formation and rubber-like behavior due to short range order.
The main pseudoelastic effect comes from a stress-induced phase transformation. The figure on the right exhibits how this process occurs.
Here a load is isothermally applied to a SMA above the austenite finish temperature, A, but below the martensite deformation temperature, M. The figure above illustrates how this is possible, by relating the pseudoelastic stress-induced phase transformation to the shape memory effect temperature induced phase transformation. For a particular point on A it is possible to choose a point on the M line with a higher temperature, as long as that point M also has a higher stress. The material initially exhibits typical elastic-plastic behavior for metals. However, once the material reaches the martensitic stress, the austenite will transform to martensite and detwin. As previously discussed, this detwinning is reversible when transforming back from martensite to austenite. If large stresses are applied, plastic behavior such as detwinning and slip of the martensite will initiate at sites such as grain boundaries or inclusions. If the material is unloaded before plastic deformation occurs, it will revert to austenite once a critical stress for austenite is reached (σ). The material will recover nearly all strain that was induced from the structural change, and for some SMAs this can be strains greater than 10 percent. This hysteresis loop shows the work done for each cycle of the material between states of small and large deformations, which is important for many applications.
In a plot of strain versus temperature, the austenite and martensite start and finish lines run parallel. The SME and pseudoelasticity are actually different parts of the same phenomenon, as shown on the left.
The key to the large strain deformations is the difference in crystal structure between the two phases. Austenite generally has a cubic structure while martensite can be monoclinic or another structure different from the parent phase, typically with lower symmetry. For a monoclinic martensitic material such as Nitinol, the monoclinic phase has lower symmetry which is important as certain crystallographic orientations will accommodate higher strains compared to other orientations when under an applied stress. Thus it follows that the material will tend to form orientations that maximize the overall strain prior to any increase in applied stress. One mechanism that aids in this process is the twinning of the martensite phase. In crystallography, a twin boundary is a two-dimensional defect in which the stacking of atomic planes of the lattice are mirrored across the plane of the boundary. Depending on stress and temperature, these deformation processes will compete with permanent deformation such as slip.
It is important to note that σ is dependent on parameters such as temperature and the number of nucleation sites for phase nucleation. Interfaces and inclusions will provide general sites for the transformation to begin, and if these are great in number, it will increase the driving force for nucleation. A smaller σ will be needed than for homogeneous nucleation. Likewise, increasing temperature will reduce the driving force for the phase transformation, so a larger σ will be necessary. One can see that as you increase the operational temperature of the SMA, σ will be greater than the yield strength, σ, and superelasticity will no longer be observable. | 0 | Metallurgy |
eIF2 activity is regulated by a mechanism involving both guanine nucleotide exchange and phosphorylation. Phosphorylation takes place at the α-subunit, which is a target for a number of serine kinases that phosphorylate serine 51. Those kinases act as a result of stress such as amino acid deprivation (GCN2), ER stress (PERK), the presence of dsRNA (PKR) heme deficiency (HRI), or interferon. Once phosphorylated, eIF2 shows increased affinity for eIF2B, its GEF. However, eIF2B is able to exchange GDP for GTP only if eIF2 is in its unphosphorylated state. Phosphorylated eIF2, however, due to its stronger binding, acts as an inhibitor of its own GEF (eIF2B). Since the cellular concentration of eIF2B is much lower than that of eIF2, even a small amount of phosphorylated eIF2 can completely abolish eIF2B activity by sequestration. Without the GEF, eIF2 can no longer be returned to its active (GTP-bound) state. As a consequence, translation comes to a halt since initiation is no longer possible without any available ternary complex. Furthermore, low concentration of ternary complex allows the expression of GCN4 (starved condition), which, in turn, results in increased activation of amino acid synthesis genes | 1 | Gene expression + Signal Transduction |
Work hardening is a consequence of plastic deformation, a permanent change in shape. This is distinct from elastic deformation, which is reversible. Most materials do not exhibit only one or the other, but rather a combination of the two. The following discussion mostly applies to metals, especially steels, which are well studied. Work hardening occurs most notably for ductile materials such as metals. Ductility is the ability of a material to undergo plastic deformations before fracture (for example, bending a steel rod until it finally breaks).
The tensile test is widely used to study deformation mechanisms. This is because under compression, most materials will experience trivial (lattice mismatch) and non-trivial (buckling) events before plastic deformation or fracture occur. Hence the intermediate processes that occur to the material under uniaxial compression before the incidence of plastic deformation make the compressive test fraught with difficulties.
A material generally deforms elastically under the influence of small forces; the material returns quickly to its original shape when the deforming force is removed. This phenomenon is called elastic deformation. This behavior in materials is described by Hookes Law. Materials behave elastically until the deforming force increases beyond the elastic limit, which is also known as the yield stress. At that point, the material is permanently deformed and fails to return to its original shape when the force is removed. This phenomenon is called plastic deformation. For example, if one stretches a coil spring up to a certain point, it will return to its original shape, but once it is stretched beyond the elastic limit, it will remain deformed and wont return to its original state.
Elastic deformation stretches the bonds between atoms away from their equilibrium radius of separation, without applying enough energy to break the inter-atomic bonds. Plastic deformation, on the other hand, breaks inter-atomic bonds, and therefore involves the rearrangement of atoms in a solid material. | 0 | Metallurgy |
Thaumasite is a calcium silicate mineral, containing Si atoms in unusual octahedral configuration, with chemical formula CaSi(OH)(CO)(SO)·12HO, also sometimes more simply written as CaSiO·CaCO·CaSO·15HO.
Thaumasite is formed under special conditions in the presence of sulfate ions in concrete containing, or exposed to, a source of carbonate anions such as limestone aggregates, or finely milled limestone filler (). Bicarbonate anions () dissolved in groundwater may also contribute to the reaction. The detrimental reaction proceeds at the expense of calcium silicate hydrates (C-S-H, with dashes denoting here their non-stoichiometry) present in the hardened cement paste (HCP). The thaumasite form of sulfate attack (TSA) is a particular type of very destructive sulfate attack. C-S-H are the "glue" in the hardened cement paste filling the interstices between the concrete aggregates. As the TSA reaction consumes the silicates of the "cement glue", it can lead to a harmful decohesion and a softening of concrete. Expansion and cracking are more rarely observed. Unlike the common sulfate attack, in which the calcium hydroxide (portlandite) and calcium aluminate hydrates react with sulfates to respectively form gypsum and ettringite (an expansive phase), in the case of TSA the C-S-H ensuring the cohesion of HCP and aggregates are destroyed. As a consequence, even concrete containing low- sulfate-resisting Portland cement may be affected.
TSA is sometimes easily recognizable on the field when examining the altered concrete. TSA-affected concrete becomes powdery and can be dug with a scoop, or even scrapped with the fingers. Concrete decohesion is very characteristic of TSA.
TSA was first identified during the years 1990 in England in the United Kingdom in the foundation piles of bridges of the motorway M5 located in the Kimmeridgian marls. These marls are a mixture of clay and limestone sedimented under anoxic conditions and are rich in pyrite (, a disulfide). Once these marls were excavated, pyrite was exposed to atmospheric oxygen or oxygen-rich infiltration water and rapidly oxidized. Pyrite oxidation produces sulfuric acid. In its turn, reacts with portlandite (present in the hardened cement paste, HCP) and calcite ( (present in limestone aggregates or in carbonated HCP). The strong acidification of the medium caused by pyrite oxidation releases bicarbonate ions () or carbon dioxide () along with calcium () and sulfate ions ().
Full pyrite oxidation can be schematized as:
The sulfuric acid released by pyrite oxidation then reacts with portlandite ()) present in the hardened cement paste to give gypsum:
When concrete also contains limestone aggregates or a filler addition, reacts with calcite () and water to also form gypsum while releasing :
Gypsum is relatively soluble in water , so there is plenty of calcium and sulfates ions available for TSA.
Simultaneously, carbonic acid () dissolves calcite to form soluble calcium bicarbonate:
So, when all the chemical ingredients necessary to react with C-S-H from the hardened cement paste in concrete are present together the TSA reaction can occur. When grounds rich in pyrite, such as many clays or marls, are excavated for civil engineering works, the strong acidification produced by pyrite oxidation is the powerful driving force triggering TSA because it frees up and mobilizes all the ions needed to attack C-S-H and to form thaumasite ().
TSA is favored by a low temperature, although it can be encountered at higher temperature in warm areas. The reason is to be found in the retrograde solubility of most of the ingredients needed for the TSA reaction. Indeed, the solubility of dissolved carbon dioxide (), portlandite (), calcite (), and gypsum (·2), increases when the temperature is lowered. This is because the dissolution reactions of these mineral species are exothermic and release heat. A lower temperature facilitates the heat release and therefore favors the exothermic reaction. Only the solubility of silica (from C-S-H) increases with temperature because silica dissolution is an endothermic process which requires heat to proceed. | 0 | Metallurgy |
In the iron–carbon system (i.e. plain-carbon steels and cast irons) it is a common constituent because ferrite can contain at most 0.02wt% of uncombined carbon. Therefore, in carbon steels and cast irons that are slowly cooled, a portion of the carbon is in the form of cementite. Cementite forms directly from the melt in the case of white cast iron. In carbon steel, cementite precipitates from austenite as austenite transforms to ferrite on slow cooling, or from martensite during tempering. An intimate mixture with ferrite, the other product of austenite, forms a lamellar structure called pearlite.
While cementite is thermodynamically unstable, eventually being converted to austenite (low carbon level) and graphite (high carbon level) at higher temperatures, it does not decompose on heating at temperatures below the eutectoid temperature (723 °C) on the metastable iron-carbon phase diagram.
Mechanical properties are as follows: room temperature microhardness 760–1350 HV; bending strength 4.6–8 GPa, Young's modulus 160–180 GPa, indentation fracture toughness 1.5–2.7 MPa√m. | 0 | Metallurgy |
Heparin and heparan sulfate (HS) are mammalian glycosaminoglycans with the highest negative charge density of known biological macromolecules. They bind by ionic interactions with a variety of proteins. Heparin is widely used as an injectable anticoagulant. SFRP1 are heparin-binding proteins, with the heparin-binding domain within the C-terminal region of the SFRP1 protein. In vitro studies show that SFRP1 is stabilized by heparin, suggesting that heparin or endogenous heparan-sulfate proteoglycan (HSPG) has the potential to promote SFRP1/Wnt binding by serving as a scaffold to facilitate interaction between SFRP1 and Wnt proteins. Lowering HSPG levels in tissue have been shown to impair Wnt signaling in vivo, supporting the idea that HSPG plays an important role in Wnt signaling regulation. Furthermore, SFRP1 is tyrosine-sulfated at two N-terminal tyrosines; this modification is, however, inhibited by heparin. Tyrosine sulfation could partially destabilize the SFRP1 protein, which is supported by previous studies showing that SFRP1 is susceptible to degradation in the absence of heparin. The finding that heparin can inhibit intracellular post-translational modification of SFRP1 was surprising. This indicates that heparin may inhibit the process of tyrosine sulfation, for example, by tyrosyl-protein sulfotransferases enzymes or sulfate donor pathways. Since heparin is highly negatively charged and cannot permeate the membrane, it must activate a signal transduction pathway to carry out its effect. It is well known that fibroblast growth factors (FGFs) bind heparin with relatively high affinity. HSPGs have also been shown to be involved in FGF cell signaling. Zhong et al. revealed a specificity of FGFs and FGF receptors on SFRP1 accumulation, demonstrating that FGF and their receptors are involved in post-translational modification of SFRP1. As stated above, SFRP1 has been shown to attenuate the malignant phenotype and decrease the growth of tumors. Thus, Heparin is a potential drug that could be used to stabilize and accumulate SFRP1 in cancer cells. | 1 | Gene expression + Signal Transduction |
Initially, the chemical reactions that normally occur in the cement paste, generate an alkaline environment, bringing the solution in the cement paste pores to pH values around 13. In these conditions, passivation of steel rebar occurs, due to a spontaneous generation of a thin film of oxides able to protect the steel from corrosion. Over time, the thin film can be damaged, and corrosion of steel rebar starts. The corrosion of steel rebar is one of the main causes of premature failure of reinforced concrete structures worldwide, mainly as a consequence of two degradation processes, carbonation and penetration of chlorides. With regard to the corrosion degradation process, a simple and accredited model for the assessment of the service life is the one proposed by Tuutti, in 1982. According to this model, the service life of a reinforced concrete structure can be divided into two distinct phases.
* , initiation time: from the moment the structure is built, to the moment corrosion initiates on steel rebar. More in particular, it is the time required for aggressive agents (carbon dioxide and chlorides) to penetrate the concrete cover thickness, reach the embedded steel rebar, alter the initial passivation condition on steel surface and cause corrosion initiation.
* , propagation time: which is defined as the time from the onset of active corrosion until an ultimate limit state is reached, i.e. corrosion propagation reaches a limit value corresponding to unacceptable structural damage, such as cracking and detachment of the concrete cover thickness.
The identification of initiation time and propagation time is useful to further identify the main variables and processes influencing the service life of the structure which are specific of each service life phase and of the degradation process considered. | 0 | Metallurgy |
Poroma is a benign, relatively common skin tumor that has the cellular features similar to those of a sweat gland duct. This tumor typically occurs as a solitary stalkless nodule on the soles and palms but may occur in any area where there are sweat glands. Porocarcinoma (also termed eccrine porocarcinoma and malignant eccrine poroma) is an extremely rare malignant counterpart of poromas. It may arise from a longstanding poroma but more commonly appears to develop independently of any precursor poroma. Porocarcinoma tumors predominantly afflict elderly individuals. A study of 104 poroma tumors detected the YAP1-NUTM1 and WWTR1-NUTM1 fusion genes in 21 cases and 1 case, respectively, while the same study of 11 porocarcinoma tumors detected the YAP1-NUTM1 fusion gene in 6 cases. Expression of the NUTM1 (fusion) protein was observed in 25 poroma and 6 porocarcinoma cases but not in a wide range of other skin tumor types. Studies on cultured immortalized human dermal keratinocyte (i.e. HDK) and mouse embryonic fibroblast NIH-3T3 cell lines found that the YAP1-NUTM1 and WWTR1-NUTM1 fusion genes stimulated the anchorage-independent growth of NIH-3T3 cells and activated a transcriptional enhancer factor family member (i.e. TEAD family) reporter gene. The TEAD family in mammals includes four members, TEAD1, TEAD2, TEAD3, and TEAD4 that are transcription factors, i.e. proteins that regulate the expression of various genes. TEAD family proteins have been found to promote the development, progression, and/or metastasis of various cancer types and, based on the studies just cited, are thought to do so in poromas and porocarcinomas. However, further studies are needed to confirm this association and determine if TEAD family transcription factors may be useful targets for treating the porocarcinomas. | 1 | Gene expression + Signal Transduction |
The LHCG receptor's main function is the regulation of steroidogenesis. This is accomplished by increasing the intracellular levels of the enzyme cholesterol side chain cleaving enzyme, a member of the cytochrome P450 family. This leads to increased conversion of cholesterol into androgen precursors required to make many steroid hormones, including testosterone and estrogens. | 1 | Gene expression + Signal Transduction |
Based on the principle of counter-current piston flow, these processes are the closest to the blast furnace or, more accurately, the stückofen. Hot reducing gases are obtained from natural gas, in a separate unit from the shaft, and injected at the bottom of the shaft, while the ore is charged at the top. The pre-reduced materials are extracted hot, but in solid form, from the bottom of the shaft. This similarity to a blast furnace without its crucible made it one of the first processes explored by metallurgists, but the failures of the German Gurlt in 1857, and the French Eugène Chenot (son of Adrien) around 1862, led to the conclusion that "the reduction of iron ore [...] is therefore [not] possible in large quantities by gas alone".
Developed in the 1970s, the Midrex process is the best example of a continuous direct reduction process. As much a technical success as a commercial one, since 1980 it has accounted for around two-thirds of the world's production of pre-reduced materials. Its similarity to the blast furnace means that it shares some of its advantages, such as high production capacity, and some disadvantages, such as the relative difficulty of controlling several simultaneous reactions in a single reactor (since the nature of the product changes considerably as it travels through the vessel). The strategy of selling turnkey units, combined with a cautious increase in production capacity, has given this process good financial and technical visibility... compared with the often dashed hopes of competing processes.
Its direct competitor, the HYL III process, is the result of a research effort by the Tenova Group (de), heir to the Mexican Hylsa pioneers. Accounting for almost 20% of pre-reduced product production, it differs from the Midrex process in that it features an in-house reforming unit for the production of reducing gases.
Other processes have been developed based on this continuous reactor principle. Some, like ULCORED, are still at the study stage. Most have only been developed in a single country, or by a single company. Others were failures, such as the NSC process, of which a single plant was built in 1984 and converted to HYL III in 1993, ARMCO (a single unit commissioned in 1963 and shut down in 1982) or PUROFER (3 units operational from 1970 to 1979, small-scale production resumed in 1988).
Coal-fired processes are variants of natural gas processes, where the gas can be synthesized from coal in an additional unit. Among these variants, the MXCOL, of which one unit has been operational since 1999 and two are under construction, is a Midrex fed by a coal gasification unit. Technically mature but more complex, they are at a disadvantage compared with equivalent gas-fired processes, which require slightly less investment. | 0 | Metallurgy |
Since microsphere beads are easily suspended in solution and each microsphere retains its identity when hybridized to the test sample, a typical suspension array experiment can analyze a wide range of biological analysis in a single reaction, called "multiplexing". In general, each type of microsphere used in an array is individually prepared in bulk. For example, the commercially available microsphere arrays from Luminex xMAP technology uses a 10X10 element array. This array involves beads with red and infrared dyes, each with ten different intensities, to give a 100-element array. Thus, the array size would increase exponentially if multiple dyes are used. For example, five different dyes with 10 different intensities per dye will give rise to 100,000 different array elements. | 1 | Gene expression + Signal Transduction |
Eutectic NaK (NaK-77, an alloy of 77% potassium and 23% sodium by mass) can be used as a hydraulic fluid in high-temperature and high-radiation environments, for temperature ranges of . Its bulk modulus at is 2.14 GPa, higher than of a hydraulic oil at room temperature. Its lubricity is poor, so positive-displacement pumps are unsuitable and centrifugal pumps have to be used. Addition of caesium shifts the useful temperature range to . NaK-77 was tested in hydraulic and fluidic systems for the Supersonic Low Altitude Missile. NaK may also be used to transmit forces inside high temperature pressure transducers as an alternative to mercury. | 0 | Metallurgy |
mTOR is the catalytic subunit of two structurally distinct complexes: mTORC1 and mTORC2. The two complexes localize to different subcellular compartments, thus affecting their activation and function. Upon activation by Rheb, mTORC1 localizes to the Ragulator-Rag complex on the lysosome surface where it then becomes active in the presence of sufficient amino acids. | 1 | Gene expression + Signal Transduction |
Conferences are normally scheduled for May or June in Europe, North America or Asia. However, most conferences are held in Europe because the majority of the current membership resides in Europe. Conferences start with an informal reception on Sunday evening followed by two and a half days of technical sessions. Ample time is allowed for technical discussion, and various social events are scheduled in association with the conference. Typical topics include machinery and press tools, new processes, new materials, experimental methods for evaluating formability and studying press operations, springback, constitutive equations, plasticity criteria, and friction and wear with attention to interface behavior as characterized by topography and surface chemistry, lubrication, speed, and temperature. | 0 | Metallurgy |
After a cell passes the restriction point, Cyclin E - Cdk 2 hyper-phosphorylates all mono-phosphorylated isoforms. While the exact mechanism is unknown, one hypothesis is that binding to the C-terminus tail opens the pocket subunit, allowing access to all phosphorylation sites. This process is hysteretic and irreversible, and it is thought accumulation of mono-phosphorylated pRb induces the process. The bistable, switch like behavior of pRb can thus be modeled as a bifurcation point: | 1 | Gene expression + Signal Transduction |
Friction stir processing (FSP) is a method of changing the properties of a metal through intense, localized plastic deformation. This deformation is produced by forcibly inserting a non-consumable tool into the workpiece, and revolving the tool in a stirring motion as it is pushed laterally through the workpiece. The precursor of this technique, friction stir welding, is used to join multiple pieces of metal without creating the heat affected zone typical of fusion welding.
When ideally implemented, this process mixes the material without changing the phase (by melting or otherwise) and creates a microstructure with fine, equiaxed grains. This homogeneous grain structure, separated by high-angle boundaries, allows some aluminium alloys to take on superplastic properties. Friction stir processing also enhances the tensile strength and fatigue strength of the metal. In tests with actively cooled magnesium-alloy workpieces, the microhardness was almost tripled in the area of the friction stir processed seam (to 120–130 Vickers hardness). | 0 | Metallurgy |
Because of anisomycins wide use as a protein synthesis inhibitor, there have been many studies centered on the biosynthesis of anisomycin. One study by Butler in 1974 proposed possible precursors to this natural product. Fermentation of Streptomyces' with labeled amino acids was followed by a degradation of the radioactive anisomycin and deacetylanisomycin products to determine the locations of the labeled carbons. Although its pyrrolidine-based structure suggests that it is derived from proline, the results from the experiments indicated that tyrosine, glycine, methionine, and acetate are the primary precursors for the biosynthesis of anisomycin. Tyrosine and, to a limited degree, phenylalanine, contribute to C-2 of the pyrrolidine ring. Methionine is likely responsible for the methylation of the hydroxyl group on the aromatic ring as S-adenosylmethionine (SAM). Glycine or acetate account for C-4 and C-5 on the pyrrolidine ring. It was noted that deacetylanisomycin was a prominent product in the first few days of fermentation, suggesting that acetylation of the C-3 hydroxyl group by acetyl Co-A is the final step in the biosynthesis of anisomycin. The source of the nitrogen within the ring and C-3 were undetermined. However, C-3 is not likely to be provided by the carboxylic acid group of tyrosine because tracking of radioactivity indicated that tyrosine undergoes decarboxylation during fermentation. | 1 | Gene expression + Signal Transduction |
The Golden Gate assembly protocol was defined by Engler et al. 2008 to define a DNA assembly method that would give a final construct without a scar sequence, while also lacking the original restriction sites. This allows the protein to be expressed without containing unwanted protein sequences which could negatively affect protein folding or expression. By using the BsaI restriction enzyme that produces a 4 base pair overhang, up to 240 unique, non-palindromic sequences can be used for assembly.
Plasmid design and assembly
In Golden Gate cloning, each DNA fragment to be assembled is placed in a plasmid, flanked by inward facing BsaI restriction sites containing the programmed overhang sequences. For each DNA fragment, the 3 overhang sequence is complementary to the 5 overhang of the next downstream DNA fragment. For the first fragment, the 5 overhang is complementary to the 5 overhang of the destination plasmid, while the 3 overhang of the final fragment is complementary to the 3 overhang of the destination plasmid. Such a design allows for all DNA fragments to be assembled in a one-pot reaction (where all reactants are mixed together), with all fragments arranged in the correct sequence. Successfully assembled constructs are selected by detecting the loss of function of a screening cassette that was originally in the destination plasmid.
MoClo and Golden Braid
The original Golden Gate Assembly only allows for a single construct to be made in the destination vector . To enable this construct to be used in a subsequent reaction as an entry vector, the MoClo and Golden Braid standards were designed.
The MoClo standard involves defining multiple tiers of DNA assembly:
* Tier 1: Tier 1 assembly is the standard Golden Gate assembly, and genes are assembled from their components parts (DNA parts coding for genetic elements like UTRs, promoters, ribosome binding sites or terminator sequences). Flanking the insertion site of the tier 1 destination vectors are a pair of inward cutting BpiI restriction sites. This allows these plasmids to be used as entry vectors for tier two destination vectors.
* Tier 2: Tier 2 assembly involves further assembling the genes assembled in tier 1 assembly into multi-gene constructs. If there is a need for further, higher tier assembly, inward cutting BsaI restriction sites can be added to flank the insertion sites. These vectors can then be used as entry vectors for higher tier constructs.
Each assembly tier alternates the use of BsaI and BpiI restriction sites to minimise the number of forbidden sites, and sequential assembly for each tier is achieved by following the Golden Gate plasmid design. Overall, the MoClo standard allows for the assembly of a construct that contains multiple transcription units, all assembled from different DNA parts, by a series of one-pot Golden Gate reactions. However, one drawback of the MoClo standard is that it requires the use of dummy parts with no biological function, if the final construct requires less than four component parts. The Golden Braid standard on the other hand introduced a pairwise Golden Gate assembly standard.
The Golden Braid standard uses the same tiered assembly as MoClo, but each tier only involves the assembly of two DNA fragments, i.e. a pairwise approach. Hence in each tier, pairs of genes are cloned into a destination fragment in the desired sequence, and these are subsequently assembled two at a time in successive tiers. Like MoClo, the Golden Braid standard alternates the BsaI and BpiI restriction enzymes between each tier.
The development of the Golden Gate assembly methods and its variants has allowed researchers to design tool-kits to speed up the synthetic biology workflow. For example, EcoFlex was developed as a toolkit for E. Coli that uses the MoClo standard for its DNA parts, while a similar toolkit has also been developed for engineering the Chlamydomonas reinhardtii microalgae. | 1 | Gene expression + Signal Transduction |
The functional mammalian sAC consist of two heterologous catalytic domains (C1 and C2), forming the 50 kDa amino terminus of the protein. The additional ~140 kDa C terminus of the enzyme includes an autoinhibitory region, canonical P-loop, potential heme-binding domain, and leucine zipper-like sequence, which are a form of putative regulatory domains.
A truncated form of the enzyme only includes the C1 and C2 domains and it is refers to as the minimal functional sAC variant. This sAC-truncated form has cAMP-forming activity much higher than its full-length type. These sAC variants are stimulated by HCO3- and respond to all known selective sAC inhibitors. Crystal structures of this sAC variant comprising only the catalytic core, in apo form and in as complex with various substrate analogs, products, and regulators, reveal a generic Class III AC architecture with sAC-specific features. The structurally related domains C1 and C2 form the typical pseudo-heterodimer, with one active site. The pseudo-symmetric site accommodates the sAC-specific activator HCO3−, which activates by triggering a rearrangement of Arg176, a residue connecting both sites. The anionic sAC inhibitor 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) acts as a blocker for the entrance to active site and bicarbonate binding pocket. | 1 | Gene expression + Signal Transduction |
mTOR Complex 1 (mTORC1) is composed of mTOR, regulatory-associated protein of mTOR (Raptor), mammalian lethal with SEC13 protein 8 (mLST8) and the non-core components PRAS40 and DEPTOR. This complex functions as a nutrient/energy/redox sensor and controls protein synthesis. The activity of mTORC1 is regulated by rapamycin, insulin, growth factors, phosphatidic acid, certain amino acids and their derivatives (e.g., -leucine and β-hydroxy β-methylbutyric acid), mechanical stimuli, and oxidative stress. | 1 | Gene expression + Signal Transduction |
The Dhar iron pillar is a now-fragmented iron column located in the Dhar town of Madhya Pradesh, India. The exact origins of the pillar are unknown, but according to the local tradition, it was a victory column erected by the 11th century Paramara king Bhoja.
Three of its fragments are now located near the 15th century Lat Masjid ("pillar mosque"), which is named after the pillar (called "lāṭ" in Hindi). A fourth portion is believed to be missing. The original pillar tapered from bottom to top: the bottom fragment has a square cross-section; the middle fragment has square and octagonal cross-sections, and the top fragment has an octagonal cross-section with a small circular part at the end. The total length of the three fragments is , which indicates that the original pillar must have been twice as high as the iron pillar of Delhi. The combined weight of the fragments is estimated at around , which is at least more than the Delhi pillar's weight. At the time of its erection, it was probably the largest forge-welded iron pillar in the world. | 0 | Metallurgy |
Tetrathionate is a product of the oxidation of thiosulfate, , by iodine, I:
:2 + I → + 2I
The use of bromine instead of iodine is dubious as excess bromine will oxidize the thiosulfate to sulfate. | 0 | Metallurgy |
Mechanistically, eukaryotic translation termination matches its prokaryotic counterpart. In this case, termination of the polypeptide chain is achieved through the hydrolytic action of a heterodimer consisting of release factors, eRF1 and eRF3. Translation termination is said to be leaky in some cases as noncoding-tRNAs may compete with release factors to bind stop codons. This is possible due to the matching of 2 out 3 bases within the stop codon by tRNAs that may occasionally outcompete release factor base pairing. An example of regulation at the level of termination is functional translational readthrough of the lactate dehydrogenase gene LDHB. This readthrough provides a peroxisomal targeting signal that localizes the distinct LDHBx to the peroxisome. | 1 | Gene expression + Signal Transduction |
In 2021, calcium was the 243rd most commonly prescribed medication in the United States, with more than 1million prescriptions. | 1 | Gene expression + Signal Transduction |
The Sepro Leach Reactor is a high concentration leach reactor developed to treat the gold concentrate produced by the Falcon Concentrator. The unit consists of a concentrate holding tank and a leach tank and impeller which are linked by a Sepro vertical bowl pump. The SLR uses either peroxide or oxygen gas to achieve elevated levels of dissolved oxygen required to accelerate the leaching process with no reagents required. The pregnant leach solution produced can be directly electrowon. With the addition of an electrowinning unit the final product becomes a gold plated carbon that can be directly refined to produce gold bullion. Extensive test work of the SLR on site has shown over 99% of the target mineral is recovered through a simple, fully automated process that is easily incorporated into recovery operations. Sepro Mineral Systems Corp. supplies SLR units with capacities ranging from . | 0 | Metallurgy |
Several single nucleotide polymorphisms within the TCF7L2 gene have been associated with type 2 diabetes. Studies conducted by Ravindranath Duggirala and Michael Stern at The University of Texas Health Science Center at San Antonio were the first to identify strong linkage for type 2 diabetes at a region on Chromosome 10 in Mexican Americans This signal was later refined by Struan Grant and colleagues at DeCODE genetics and isolated to the TCF7L2 gene. The molecular and physiological mechanisms underlying the association of TCF7L2 with type 2 diabetes are under active investigation, but it is likely that TCF7L2 has important biological roles in multiple metabolic tissues, including the pancreas, liver and adipose tissue. TCF7L2 polymorphisms can increase susceptibility to type 2 diabetes by decreasing the production of glucagon-like peptide-1 (GLP-1). | 1 | Gene expression + Signal Transduction |
Pol III has three classes of initiation, which start with different factors recognizing different control elements but all converging on TFIIIB (similar to TFIIB-TBP; consists of TBP/TRF, a TFIIB-related factor, and a B″ unit) recruiting the Pol III preinitiation complex. The overall architecture resembles that of Pol II. Only TFIIIB needs to remain attached during elongation. | 1 | Gene expression + Signal Transduction |
Recovery of metals from oxide matrixes is generally carried out using mineral acids. However, electrochemical dissolution of metal oxides in DES can allow to enhance the dissolution up to more than 10 000 times in pH neutral solutions.
Studies have shown that ionic oxides such as ZnO tend to have high solubility in ChCl:malonic acid, ChCl:urea and Ethaline, which can resemble the solubilities in aqueous acidic solutions, e.g., HCl. Covalent oxides such as TiO, however, exhibits almost no solubility. The electrochemical dissolution of metal oxides is strongly dependent on the proton activity from the HBD, i.e. capability of the protons to act as oxygen acceptors, and on the temperature. It has been reported that eutectic ionic fluids of lower pH-values, such as ChCl:oxalic acid and ChCl:lactic acid, allow a better solubility than that of higher pH (e.g., ChCl:acetic acid). Hence, different solubilities can be obtained by using, for instance, different carboxylic acids as HBD. | 0 | Metallurgy |
Humans and chimpanzees share ten NANOG pseudogenes (NanogP2-P11) during evaluation, two of them are located on the X chromosome and they characterized by the 5’ promoter sequences and the absence of introns as a result of mRNA retrotransposition all in the same places: one duplication pseudogene and nine retropseudogenes. Of the nine shared NANOG retropseudogenes, two lack the poly-(A) tails characteristic of most retropseudogenes, indicating that copying errors occurred during their creation. Due to the high improbability that the same pseudogenes (copying errors included) would exist in the same places in two unrelated genomes, evolutionary biologists point to NANOG and its pseudogenes as providing evidence of common descent between humans and chimpanzees. | 1 | Gene expression + Signal Transduction |
Tribocorrosion is a material degradation process due to the combined effect of corrosion and wear. The name tribocorrosion expresses the underlying disciplines of tribology and corrosion. Tribology is concerned with the study of friction, lubrication and wear (its name comes from the Greek "tribo" meaning to rub) and corrosion is concerned with the chemical and electrochemical interactions between a material, normally a metal, and its environment. As a field of research tribocorrosion is relatively new, but tribocorrosion phenomena have been around ever since machines and installations are being used.
Wear is a mechanical material degradation process occurring on rubbing or impacting surfaces, while corrosion involves chemical or electrochemical reactions of the material. Corrosion may accelerate wear and wear may accelerate corrosion. One then speaks of corrosion accelerated wear or wear accelerated corrosion. Both these phenomena, as well as fretting corrosion (which results from small amplitude oscillations between contacting surfaces) fall into the broader category of tribocorrosion. Erosion-corrosion is another tribocorrosion phenomenon involving mechanical and chemical effects: impacting particles or fluids erode a solid surface by abrasion, chipping or fatigue while simultaneously the surface corrodes. | 0 | Metallurgy |
Shadow enhancers are groups of two or more enhancers that control the same target gene and drive overlapping spatiotemporal expression patterns. Shadow enhancers are found in a wide range of organisms, from insects to plants to mammals, particularly in association with developmental genes. While seemingly redundant, the individual enhancers of a shadow enhancer group have been shown to be critical for proper gene expression in the face of both environmental and genetic perturbations. Such perturbations may exacerbate fluctuations in upstream regulators. | 1 | Gene expression + Signal Transduction |
The Betts electrolytic process is an industrial process for purification of lead from bullion. Lead obtained from its ores is impure because lead is a good solvent for many metals. Often these impurities are tolerated, but the Betts electrolytic process is used when high purity lead is required, especially for bismuth-free lead. | 0 | Metallurgy |
The CD family of co-receptors are a well-studied group of extracellular receptors found in immunological cells. The CD receptor family typically act as co-receptors, illustrated by the classic example of CD4 acting as a co-receptor to the T cell receptor (TCR) to bind major histocompatibility complex II (MHC-II). This binding is particularly well-studied in T-cells where it serves to activate T-cells that are in their resting (or dormant) phase and to cause active cycling T-cells to undergo programmed cell death. Boehme et al. demonstrated this interesting dual outcome by blocking the binding of CD4 to MHC-II which prevented the programmed cell death reaction that active T-cells typically display.
The CD4 receptor is composed of four concatamerized Ig-like domains and is anchored to the cell membrane by a single transmembrane domain. CD family receptors are typically monomers or dimers, though they are all primarily extracellular proteins. The CD4 receptor in particular interacts with murine MHC-II following the "ball-on-stick" model, where the Phe-43 ball fits into the conserved hydrophobic α2 and β2 domain residues. During binding with MHC-II, CD4 maintains independent structure and does not form any bonds with the TCR receptor.
The members of the CD family of co-receptors have a wide range of function. As well as being involved in forming a complex with MHC-II with TCR to control T-cell fate, the CD4 receptor is infamously the primary receptor that HIV envelope glycoprotein GP120 binds to. In comparison, CD28 acts as a ‘co-coreceptor’ (costimulatory receptor) for the MHC-II binding with TCR and CD4. CD28 increases the IL-2 secretion from the T-cells if it is involved in the initial activation; however, CD28 blockage has no effect on programmed cell death after the T-cell has been activated. | 1 | Gene expression + Signal Transduction |
The most common type of frameshifting is −1 frameshifting or programmed −1 ribosomal frameshifting (−1 PRF). Other, rarer types of frameshifting include +1 and −2 frameshifting. −1 and +1 frameshifting are believed to be controlled by different mechanisms, which are discussed below. Both mechanisms are kinetically driven. | 1 | Gene expression + Signal Transduction |
Communication between neurons happens primarily through chemical neurotransmission at the synapse. Neurotransmitters are packaged into synaptic vesicles for release from the presynaptic cell into the synapse, from where they diffuse and can bind to postsynaptic receptors. While most presynaptic cells are historically thought to release one vesicle at a time per active site, more recent research has pointed towards the possibility of multiple vesicles being released from the same active site (multivesicular release; MVR) in response to an action potential. | 1 | Gene expression + Signal Transduction |
P. aeruginosa is an opportunistic human pathogen associated with cystic fibrosis. In P. aeruginosa infections, quorum sensing is critical for biofilm formation and pathogenicity. P. aeruginosa contains two pairs of LuxI/LuxR homologs, LasI/LasR and RhlI, RhlR. LasI and RhlI are synthase enzymes that catalyze the synthesis of N-(3-oxododecanoyl)-homoserine lactone and N-(butyryl)-homoserine lactone, respectively. The LasI/LasR and the RhlI/RhlR circuits function in tandem to regulate the expression of a number of virulence genes. At a threshold concentration, LasR binds N-(3-oxododecanoyl)-homoserine lactone. Together this bound complex promotes the expression of virulence factors that are responsible for early stages of the infection process.
LasR bound by its autoinducer also activates the expression of the RhlI/RhlR system in P. aeruginosa. This causes the expression of RhlR which then binds its autoinducer, N-(butryl)-homoserine lactone. In turn, autoinducer-bound RhlR activates a second class of genes involved in later stages of infection, including genes needed for antibiotic production. Presumably, antibiotic production by P. aeruginosa is used to prevent opportunistic infections by other bacterial species. N-(3-oxododecanoyl)-homoserine lactone prevents binding between N-(butryl)-homoserine lactone and its cognate regulator, RhlR. It is believed that this control mechanism allows P. aeruginosa to initiate the quorum-sensing cascades sequentially and in the appropriate order so that a proper infection cycle can ensue. | 1 | Gene expression + Signal Transduction |
It may be necessary to repair a concrete structure following damage (e.g. due to age, chemical attack, fire, impact, movement or reinforcement corrosion). Strengthening may be necessary if the structure is weakened (e.g. due to design or construction errors, excessive loading, or because of a change of use). | 0 | Metallurgy |
Sealants are an alternative to solder where additional strength is not required. In most cases, sealants should not be necessary with a properly designed copper installation. They are at best a relatively short-term solution requiring frequent maintenance. Regardless, sealant-filled joints have been used successfully as a secondary waterproofing measure for standing seam and batten seam roofing applications where low-sloped roofs are less than . Sealants can also be used in joints that are primarily designed to accommodate thermal movement of the copper.
The sealants used should be tested by the manufacturer and designated as compatible for use with copper.
In general, butyl, polysulfide, polyurethane, and other inorganic or rubber-based sealants are reasonably compatible with copper. Acrylic, neoprene, and nitrile-based sealants actively corrode copper. Silicone sealants are somewhat successful with copper but their suitability should be verified before application. | 0 | Metallurgy |
Thiosulfate ion is known in the very rare mineral sidpietersite . The presence of this anion in the mineral bazhenovite was disputed. | 0 | Metallurgy |
Alloy systems that are liquid at room temperature have thermal conductivity far superior to ordinary non-metallic liquids, allowing liquid metal to efficiently transfer energy from the heat source to the liquid. They also have a higher electrical conductivity that allows the liquid to be pumped more efficiently, by electromagnetic pumps. This results in the use of these materials for specific heat conducting and/or dissipation applications.
Another advantage of liquid alloy systems is their inherent high densities. | 0 | Metallurgy |
Electrowinning, also called electroextraction, is the electrodeposition of metals from their ores that have been put in solution via a process commonly referred to as leaching. Electrorefining uses a similar process to remove impurities from a metal. Both processes use electroplating on a large scale and are important techniques for the economical and straightforward purification of non-ferrous metals. The resulting metals are said to be electrowon.
In electrowinning, an electrical current is passed from an inert anode through a leach solution containing the dissolved metal ions so that the metal is recovered as it is reduced and deposited in an electroplating process onto the cathode. In electrorefining, the anode consists of the impure metal (e.g., copper) to be refined. The impure metallic anode is oxidized and the metal dissolves into solution. The metal ions migrate through the electrolyte towards the cathode where the pure metal is deposited. Insoluble solid impurities sedimenting below the anode often contain valuable rare elements such as gold, silver and selenium. | 0 | Metallurgy |
Symplekin (SYMPK) is a scaffolding protein that mediates the interaction between CPSF and CstF.
In mammalian CPSF, both cleavage factor I (CFI) and cleavage and polyadenylation specificity factor (CPSF) are required for cleavage and polyadenylation whereas cleavage stimulation factor (CstF) is only essential for the cleavage step. CPSF and CstF travel along with RNA polymerase II (RNAP II) during nascent gene transcription in search of the PAS.
Cleavage factor I (CFI) is made of 25 (CPSF5), 59 (CPSF7), and 68 (CPSF6) kDa proteins. Cleavage factor II (CFII) is made of Pcf11, Clp1, and cleavage stimulation factor (CstF). CFII binds to the RNAP II C-terminal domain and other CpA factors.
Cleavage stimulation factor (CstF) has three subunits: CstF77 (CstF3), CstF50 (CstF1), and CstF64 (CstF2 and CstF2T). CstF recognizes the PAS that is 20 nucleotides downstream the signaling region of the cleavage site, which is a GU-rich sequence motif followed by U-rich sequences. CstF contributes to the selection of the cleavage site, as well as alternative polyadenylation. | 1 | Gene expression + Signal Transduction |
The process of detonation spraying was first developed in 1955 by H.B. Sargent, R.M. Poorman and H. Lamprey and was subsequently patented. It was first made commercially available as the D-Gun Process by Union Carbide in the same year. It was further developed in the 1960s by the Paton Institute in Kiev (Ukraine), into a technology that is still currently commercially available in the US by Demeton Technologies (West Babylon). | 0 | Metallurgy |
The ascidian mitochondrial code (translation table 13) is a genetic code found in the mitochondria of Ascidia. | 1 | Gene expression + Signal Transduction |
While many of the proteins involved in NMD are not conserved between species, in Saccharomyces cerevisiae (yeast), there are three main factors in NMD: UPF1, UPF2 and UPF3 (UPF3A and UPF3B in humans), that make up the conserved core of the NMD pathway. All three of these factors are trans-acting elements called up-frameshift (UPF) proteins. In mammals, UPF2 and UPF3 are part of the exon-exon junction complex (EJC) bound to mRNA after splicing along with other proteins, eIF4AIII, MLN51, and the Y14/MAGOH heterodimer, which also function in NMD. UPF1 phosphorylation is controlled by the proteins SMG-1, SMG-5, SMG-6 and SMG-7.
The process of detecting aberrant transcripts occurs during translation of the mRNA. A popular model for the detection of aberrant transcripts in mammals suggests that during the first round of translation, the ribosome removes the exon-exon junction complexes bound to the mRNA after splicing occurs. If after this first round of translation, any of these proteins remain bound to the mRNA, NMD is activated. Exon-exon junction complexes located downstream of a stop codon are not removed from the transcript because the ribosome is released before reaching them. Termination of translation leads to the assembly of a complex composed of UPF1, SMG1 and the release factors, eRF1 and eRF3, on the mRNA. If an EJC is left on the mRNA because the transcript contains a premature stop codon, then UPF1 comes into contact with UPF2 and UPF3, triggering the phosphorylation of UPF1. In vertebrates, the location of the last exon-junction complex relative to the termination codon usually determines whether the transcript will be subjected to NMD or not. If the termination codon is downstream of or within about 50 nucleotides of the final exon-junction complex then the transcript is translated normally. However, if the termination codon is further than about 50 nucleotides upstream of any exon-junction complexes, then the transcript is down regulated by NMD. The phosphorylated UPF1 then interacts with SMG-5, SMG-6 and SMG-7, which promote the dephosphorylation of UPF1. SMG-7 is thought to be the terminating effector in NMD, as it accumulates in P-bodies, which are cytoplasmic sites for mRNA decay. In both yeast and human cells, the major pathway for mRNA decay is initiated by the removal of the 5’ cap followed by degradation by XRN1, an exoribonuclease enzyme. The other pathway by which mRNA is degraded is by deadenylation from 3’-5'.
In addition to the well recognized role of NMD in removing aberrant transcripts, there are transcripts that contain introns within their 3'UTRs. These messages are predicted to be NMD-targets yet they (e.g., activity-regulated cytoskeleton-associated protein, known as Arc) can play crucial biologic functions suggesting that NMD may have physiologically relevant roles. | 1 | Gene expression + Signal Transduction |
A coactivator is a type of transcriptional coregulator that binds to an activator (a transcription factor) to increase the rate of transcription of a gene or set of genes. The activator contains a DNA binding domain that binds either to a DNA promoter site or a specific DNA regulatory sequence called an enhancer. Binding of the activator-coactivator complex increases the speed of transcription by recruiting general transcription machinery to the promoter, therefore increasing gene expression. The use of activators and coactivators allows for highly specific expression of certain genes depending on cell type and developmental stage.
Some coactivators also have histone acetyltransferase (HAT) activity. HATs form large multiprotein complexes that weaken the association of histones to DNA by acetylating the N-terminal histone tail. This provides more space for the transcription machinery to bind to the promoter, therefore increasing gene expression.
Activators are found in all living organisms, but coactivator proteins are typically only found in eukaryotes because they are more complex and require a more intricate mechanism for gene regulation. In eukaryotes, coactivators are usually proteins that are localized in the nucleus. | 1 | Gene expression + Signal Transduction |
The sequence of exon 1 is highly conserved in mammalian species and editing of the pre-mRNA of this protein is likely to occur in mice, rat, dog and cow as well as humans. Even though the ECS is not conserved in non-mammals, an alternative ECS has been predicted in Zebrafish with a similar structure but in a different location. The Ecs is found downstream of the editing sites. | 1 | Gene expression + Signal Transduction |
HVAF coating technology is the combustion of propane in a compressed air stream. Like HVOF, this produces a uniform high velocity jet. HVAF differs by including a heat baffle to further stabilize the thermal spray mechanisms. Material is injected into the air-fuel stream and coating particles are propelled toward the part. HVAF has a maximum flame temperature of 3,560° to 3,650 °F and an average particle velocity of 3,300 ft/sec. Since the maximum flame temperature is relatively close to the melting point of most spray materials, HVAF results in a more uniform, ductile coating. This also allows for a typical coating thickness of 0.002–0.050". HVAF coatings also have a mechanical bond strength of greater that 12,000 psi. Common HVAF coating materials include, but are not limited to; tungsten carbide, chrome carbide, stainless steel, hastelloy, and inconel. Due to its ductile nature hvaf coatings can help resist cavitation damage. | 0 | Metallurgy |
Nuclear receptor coactivator 4, also known as Androgen Receptor Activator (ARA70), is a protein that in humans is encoded by the NCOA4 gene. It plays an important role in ferritinophagy, acting as a cargo receptor, binding to the ferritin heavy chain and latching on to ATG8 on the surface of the autophagosome. | 1 | Gene expression + Signal Transduction |
Correct selection of the material by the design engineer affects the design life of a structure. Sometimes stainless steel is not the correct choice and carbon steel would be better. There is a misconception that stainless steel has excellent corrosion resistance and will not corrode. This is not always the case and should not be used to handle deoxygenated solutions for example, as the stainless steel relies on oxygen to maintain passivation and is also susceptible to crevice corrosion.
Galvanizing or hot-dip galvanizing is used to coat steel with a layer of metallic zinc. Lead or antimony are often added to the molten zinc bath, and also other metals have been studied. | 0 | Metallurgy |
* Birchons Dictionary of Metallurgy', London, 1965
* Experimental techniques in low-temperature physics, G. K. White, Oxford University Press, Third Edition | 0 | Metallurgy |
ORs, which are located on the membranes of the cilia have been classified as a complex type of ligand-gated metabotropic channels. There are approximately 1000 different genes that code for the ORs, making them the largest gene family. An odorant will dissolve into the mucus of the olfactory epithelium and then bind to an OR. ORs can bind to a variety of odor molecules, with varying affinities. The difference in affinities causes differences in activation patterns resulting in unique odorant profiles. The activated OR in turn activates the intracellular G-protein, GOLF (GNAL), adenylate cyclase and production of cyclic AMP (cAMP) opens ion channels in the cell membrane, resulting in an influx of sodium and calcium ions into the cell, and an efflux of chloride ions. This influx of positive ions and efflux of negative ions causes the neuron to depolarize, generating an action potential. | 1 | Gene expression + Signal Transduction |
After the war, the engineers evacuated from the western regions returned to their native places, which led to a shortage of engineering and technical personnel at Ural enterprises. Also, the Urals experienced a lack of funding for the reconversion of factories, since the bulk of the funds were directed to the restoration of areas liberated from occupation. At most factories in the region, the equipment required repair and updating. The equipment coming to the Urals on account of reparations from Germany and other aggressor countries was outdated and worn out.
The restructuring of the Ural metallurgy for the production of peacetime assortment was completed in 1946. Replacement and reconstruction of technological lines was often accompanied by a decrease in the quality of products due to untrained personnel and organizational problems. Since 1948, there has been a steady increase in production volumes. The construction of the Orsko-Khalilovsky Metallurgical Plant was continued, the capacities of the Magnitogorsk, Novotagilsky, Chelyabinsk, Chusovsky, and Lysvensky plants increased. The development of jet aviation, the nuclear industry, rocket engineering, and cosmonautics in the post-war period created the need for high-alloy steels, non-ferrous metal products, and the requirements for the quality of metals also sharply increased.
The main directions of technical progress in ferrous metallurgy in the post-war period were:
* further increase in the volume of blast furnaces and open-hearth furnaces
* increasing the share of steel smelting in electric furnaces and converters
* mechanization and automation of production processes
* the use of oxygen-enriched blast
* the use of natural gas as fuel
* mastering continuous and semi-continuous rolling
* introduction of continuous casting of steel
In April 1959, the Magnitogorsk Iron and Steel Works began heating open-hearth furnaces with associated gas. By the end of the 1960s, more than 80% of steel was smelted in furnaces using natural gas. Since 1956, at the Nizhny Tagil Metallurgical Plant, and later at all Ural plants, oxygen enrichment began to be used, which made it possible to increase the productivity of open-hearth furnaces by 15-25% and reduce specific fuel consumption by 15-20%. In the 1960s, more than 60% of open-hearth steel and 72% of electric steel were smelted using oxygen.
In the copper-smelting industry, the mechanization of cleaning tuyeres and loading furnaces, and automation of units were introduced. These measures made it possible to almost double the production of copper at the Krasnouralsk and Kirovgrad copper-smelting plants. Due to the introduction of the roasting of copper charge and zinc concentrates in a fluidized bed at the Chelyabinsk Zinc Plant, zinc production increased, and the integrated use of raw materials was improved. At the Ufaleisk Nickel Plant, sulfation roasting of nickel matte was introduced; at the Karabash Plant, a system for automation of the thermal regime of reverberatory furnaces was introduced, which made it possible to increase the production of nickel and copper. At the Ural aluminum smelter, a continuous bauxite leaching process was developed, and two-tier thickeners were installed, which increased the production of alumina.
The restoration and development of metallurgy in the Urals in the post-war period was stimulated by a significant increase in capital investments. In 1961-1970, out of 2,457 million rubles of capital investments in metallurgy, 2,074 million rubles (84.4%) were invested in five enterprises: Magnitogorsk Iron and Steel Works - 752 million rubles (30.6%), Chelyabinsk Metallurgical Plant - 610 million rubles (24.8%), Nizhniy Tagil Iron and Steel Works - 401 million rubles (16.3%), Orsko-Khalilovskiy Iron and Steel Works - 230 million rubles (9.4%), Verkh-Isetsky Iron and Steel Works - 81 million rubles (3.3%). From 1946 to 1965, 4 blast furnaces, 6 coke oven batteries, 14 open-hearth furnaces, 6 rolling shops were built and launched at the Magnitogorsk Iron and Steel Works. From 1947 to 1959, 4 blast furnaces, 18 open-hearths, 6 rolling mills, a unique converter shop for processing vanadium pig iron, and the country's first continuous casting machine were built at the Nizhniy Tagil Metallurgical Plant from 1947 to 1959. During the same period, blast furnaces, open-hearths, and electric furnaces were built and reconstructed at the Chelyabinsk Metallurgical Plant, and a sinter plant, electric steel-making shops No. 1 and No. 2, sheet-rolling, crimping, and section-rolling shops were put into operation. In 1950, a by-product coke plant was launched at the Orsko-Khalilovsky Metallurgical Plant; in 1955-1963 - 3 blast furnaces; in 1958-1966 - 9 open-hearth furnaces, blooming and sheet rolling mills. In 1950, the Magnitogorsk, Nizhniy Tagil and Chelyabinsk Combines smelted a total of 71.6% of all Ural pig iron, 53.4% of steel, and 57.1% of rolled products. Although the level of technical equipment of the Ural metallurgical plants was lower than in other regions, the cost of iron and steel produced was 10-15% less than the average for the USSR Ministry of Ferrous Metallurgy.
To cover the shortage of iron ore, supplies of ore from the Sokolovsko-Sarbaisky Plant in Kazakhstan began in 1957, and from the 1960s from the mines of the Kursk Magnetic Anomaly and the Kola Peninsula. At Vysokogorsky Mining and Processing Plant, the Magnetitovaya, Operational, and Yuzhnaya mines were commissioned in 1949-1954 to mine deep horizons. In 1963, the Kachkanarsky Mining and Processing Plant was put into operation, extracting iron ore with a relatively low (15-16%) iron content, but containing valuable vanadium, which significantly increases the strength properties of steel. To provide copper ore raw materials in the late 1950s - early 1960s, the Gaysky and Uchalinsky mining and processing plants were built. The main supplier of the Ural aluminum raw materials in the post-war years was the North Ural bauxite mines. The Bogoslovsky and Uralsky aluminum plants in 1949-1953 carried out the reconstruction of production facilities and mastered new technological processes.
In the 1950s and 1960s, a massive reconstruction of the Verkhnesaldinsky Metallurgical Plant was carried out with the transition to the production of semi-finished products from titanium alloys. The area of the plant was increased by 5 times. The worlds largest press with a force of 75 thousand tons was installed for stamping slabs. Rolling, forging, and stamping shops were built. Since 1966, the production of small diameter pipes has been mastered at cold rolling mills. After reconstruction, the plant became the worlds largest producer of titanium and aluminum alloys.
In the 1970s, reconstruction and refit of the Ural ferrous metallurgy enterprises were carried out. At the Kachkanarsky Mining and Processing Plant, for the first time in the Urals, the production of iron ore pellets was started, at the Nizhny Tagil Metallurgical Plant — wide flange beams, at the Chelyabinsk Metallurgical Plant — stainless steel sheets, at the Magnitogorsk Metallurgical Plant - bent profiles, and at the Verkh-Isetsky Plant — cold-rolled transformer sheets. The Ural Plant of Precision Alloys was built. The deposits of the region provided only 50% of iron ore raw materials for metallurgical plants during this period. Steelmaking in the 1970s developed through the introduction of out-of-furnace steel processing, reconstruction of open-hearth furnaces into two-shaft furnaces, and increasing the capacity of converters. Demand from the engineering and oil industries contributed to the expansion of pipe rolling enterprises. In 1975, the Sinarsky Pipe Plant launched pipe rolling shop No. 2, which produced drill pipes. In December 1976, a pipe rolling shop was launched at the Seversky Pipe Plant. At the Pervouralsky Novotrubny Plant in 1976, for the first time in the country, the production of stainless steel pipes for the nuclear industry was mastered. About 65% of Ural steel pipes were produced by the Chelyabinsk Pipe Rolling Plant, the Sinarsky Pipe Plant was the largest producer of cast iron pipes in the country. In general, Ural plants produced more than 33% of all pipes produced in the USSR. In 1980, Ural metallurgical plants smelted 28.6 million tons of pig iron, which became an absolute historical record for the region.
In 1990, Ural metallurgy accounted for the production of 24.5% of all-Union cast iron, 26.1% of steel, 27.5% of rolled products, and 30.7% of steel pipes. In the last years of the existence of the USSR, in the Ural metallurgical industry, problems with an outdated equipment park and extensive development based on outdated technologies have become aggravated. The proportion of obsolete equipment in ferrous metallurgy was estimated at 57%, in non-ferrous - 70%. About 90% of the equipment of blast furnace shops and 85% of the equipment of rolling shops in the Urals by the early 1990s had a service life of more than 20–25 years. In 1985, the share of open-hearth steel in total production in the Urals was 78.2%, while in Western countries and in Japan in the 1980s, environmentally dirty open-hearth production was discontinued. The problem of environmental pollution has significantly worsened. The surroundings of the Karabash plant have become an ecological disaster zone. There were 0.2 million hectares (200,000 hectares = 494,210.76 acres) of land that were dumps and slurry pits. | 0 | Metallurgy |
*ATF1 NM_005171
*ATF2 NM_001880
*ATF4 Activating transcription factor 4 NM_001675
*ATF6 NM_007348
*ATF7 NM_001206682
*ATF7IP NM_018179
*BTF3 NM_001207 Homo sapiens basic transcription factor 3
*E2F4 Homo sapiens E2F transcription factor 4, p107/p130-binding (E2F4), mRNA
*ERH (gene) Enhancer of rudimentary homolog of drosophila (which in turn is the first enzymatic step in pyrimidine synthesis. Regulated by MITF)
*HMGB1 High mobility group box binds DNA
*ILF2 Homo sapiens interleukin enhancer binding factor 2, 45kDa (ILF2), mRNA
*IER2 formerly ETR101 Immediate Early Protein?
*JUND Homo sapiens jun D proto-oncogene (JUND), mRNA
*TCEB2 Elongin Matheo er rar | 1 | Gene expression + Signal Transduction |
With the determination of the first structure of the complex between a G-protein coupled receptor (GPCR) and a G-protein trimer (Gαβγ) in 2011 a new chapter of GPCR research was opened for structural investigations of global switches with more than one protein being investigated. The previous breakthroughs involved determination of the crystal structure of the first GPCR, rhodopsin, in 2000 and the crystal structure of the first GPCR with a diffusible ligand (βAR) in 2007. The way in which the seven transmembrane helices of a GPCR are arranged into a bundle was suspected based on the low-resolution model of frog rhodopsin from cryogenic electron microscopy studies of the two-dimensional crystals. The crystal structure of rhodopsin, that came up three years later, was not a surprise apart from the presence of an additional cytoplasmic helix H8 and a precise location of a loop covering retinal binding site. However, it provided a scaffold which was hoped to be a universal template for homology modeling and drug design for other GPCRs – a notion that proved to be too optimistic.
Seven years later, the crystallization of β-adrenergic receptor (βAR) with a diffusible ligand brought surprising results because it revealed quite a different shape of the receptor extracellular side than that of rhodopsin. This area is important because it is responsible for the ligand binding and is targeted by many drugs. Moreover, the ligand binding site was much more spacious than in the rhodopsin structure and was open to the exterior. In the other receptors crystallized shortly afterwards the binding side was even more easily accessible to the ligand. New structures complemented with biochemical investigations uncovered mechanisms of action of molecular switches which modulate the structure of the receptor leading to activation states for agonists or to complete or partial inactivation states for inverse agonists.
The 2012 Nobel Prize in Chemistry was awarded to Brian Kobilka and Robert Lefkowitz for their work that was "crucial for understanding how G protein-coupled receptors function". There have been at least seven other Nobel Prizes awarded for some aspect of G protein–mediated signaling. As of 2012, two of the top ten global best-selling drugs (Advair Diskus and Abilify) act by targeting G protein-coupled receptors. | 1 | Gene expression + Signal Transduction |
Nuclear receptor interacting protein 1 (NRIP1) is a nuclear protein that specifically interacts with the hormone-dependent activation domain AF2 of nuclear receptors. Also known as RIP140, this protein is a key regulator which modulates transcriptional activity of a variety of transcription factors, including the estrogen receptor.
RIP140 has an important role in regulating lipid and glucose metabolism, and regulates gene expression in metabolic tissues including heart, skeletal muscle, and liver. A major role for RIP140 in adipose tissue is to block the expression of genes involved in energy dissipation and mitochondrial uncoupling, including uncoupling protein 1 and carnitine palmitoyltransferase 1b.
Estrogen-related receptor alpha (ERRa) can activate RIP140 during adipogenesis, by means of directly binding to an estrogen receptor element/ERR element and indirectly through Sp1 binding to the proximal promoter.
RIP140 suppresses the expression of mitochondrial proteins succinate dehydrogenase complex b and CoxVb and acts as a negative regulator of glucose uptake in mice. | 1 | Gene expression + Signal Transduction |
The important characteristic of these tests is that the strain rate is low, for example extension rates selected in the range from 10 to 10 s. The selection of the strain rate is very important because the susceptibility to cracking may not be evident from result of tests at too low or too high strain rate. For numerous material-environment systems, strain rates in range 10 - 10 s are used; however, the observed absence of cracking at a given strain rate should not be taken as a proof of immunity to cracking. There are known cases wherein the susceptibility to stress-corrosion cracking only became evident at strain rates as low as 10 or 10 s. Nevertheless, the method is very suitable for mechanistic studies, as well as for relative ranking of susceptibility to cracking of different alloys, or the aggressiveness of environments and the effect of temperature, pH, metallurgical condition etc.
The fastest strain rate that will still promote SCC for a given environment-material system is sometimes called the "critical strain rate", some values are given in the table: | 0 | Metallurgy |
There are various protein targets of PCAF's acetyltransferase activity including transcription factors such as Fli1, p53 and numerous histone residues. Hdm2, itself a ubiquitin ligase that targets p53, has also been demonstrated to be a target of the ubiquitin-ligase activity of PCAF. | 1 | Gene expression + Signal Transduction |
Cementite (or iron carbide) is a compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula FeC. By weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure. It is a hard, brittle material, normally classified as a ceramic in its pure form, and is a frequently found and important constituent in ferrous metallurgy. While cementite is present in most steels and cast irons, it is produced as a raw material in the iron carbide process, which belongs to the family of alternative ironmaking technologies. The name cementite originated from the theory of Floris Osmond and J. Werth, in which the structure of solidified steel consists of a kind of cellular tissue, with ferrite as the nucleus and FeC the envelope of the cells. The carbide therefore cemented the iron. | 0 | Metallurgy |
Nickel and copper are often obtained by electrowinning. These metals have some noble character, which enables their soluble cationic forms to be reduced to their pure metallic form at mild applied potentials applied between the cathode and the anode. | 0 | Metallurgy |
YeTFaSCo (The Yeast Transcription Factor Specificity Compendium) is a database of transcription factors for Saccharomyces cerevisiae. | 1 | Gene expression + Signal Transduction |