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The poly(A) tail contains binding sites for poly(A) binding proteins (PABPs). These proteins cooperate with other factors to affect the export, stability, decay, and translation of an mRNA. PABPs bound to the poly(A) tail may also interact with proteins, such as translation initiation factors, that are bound to the 5' cap of the mRNA. This interaction causes circularization of the transcript, which subsequently promotes translation initiation. Furthermore, it allows for efficient translation by causing recycling of ribosomes. While the presence of a poly(A) tail usually aids in triggering translation, the absence or removal of one often leads to exonuclease-mediated degradation of the mRNA. Polyadenylation itself is regulated by sequences within the 3′-UTR of the transcript. These sequences include cytoplasmic polyadenylation elements (CPEs), which are uridine-rich sequences that contribute to both polyadenylation activation and repression. CPE-binding protein (CPEB) binds to CPEs in conjunction with a variety of other proteins in order to elicit different responses. | 1 | Gene expression + Signal Transduction |
As access to an ionized calcium is not always available a corrected calcium may be used instead. To calculate a corrected calcium in mmol/L one takes the total calcium in mmol/L and adds it to ((40 minus the serum albumin in g/L) multiplied by 0.02). There is, however, controversy around the usefulness of corrected calcium as it may be no better than total calcium. It may be more useful to correct total calcium for both albumin and the anion gap. | 1 | Gene expression + Signal Transduction |
Stress corrosion cracking mainly affects metals and metallic alloys. A comparable effect also known as environmental stress cracking also affects other materials such as polymers, ceramics and glass. | 0 | Metallurgy |
The 2006 Nobel Prize in Chemistry was awarded to Roger D. Kornberg for creating detailed molecular images of RNA polymerase during various stages of the transcription process.
In most prokaryotes, a single RNA polymerase species transcribes all types of RNA. RNA polymerase "core" from E. coli consists of five subunits: two alpha (α) subunits of 36 kDa, a beta (β) subunit of 150 kDa, a beta prime subunit (β′) of 155 kDa, and a small omega (ω) subunit. A sigma (σ) factor binds to the core, forming the holoenzyme. After transcription starts, the factor can unbind and let the core enzyme proceed with its work. The core RNA polymerase complex forms a "crab claw" or "clamp-jaw" structure with an internal channel running along the full length. Eukaryotic and archaeal RNA polymerases have a similar core structure and work in a similar manner, although they have many extra subunits.
All RNAPs contain metal cofactors, in particular zinc and magnesium cations which aid in the transcription process. | 1 | Gene expression + Signal Transduction |
Nanocrystalline metals can be produced by rapid solidification from the liquid using a process such as melt spinning. This often produces an amorphous metal, which can be transformed into an nanocrystalline metal by annealing above the crystallization temperature. | 0 | Metallurgy |
The outgassing of volatile silicones on low Earth orbit devices leads to presence of a cloud of contaminants around the spacecraft. Together with atomic oxygen bombardment, this may lead to gradual deposition of thin layers of carbon-containing silicon dioxide. Their poor transparency is a concern in case of optical systems and solar panels. Deposits of up to several micrometers were observed after 10 years of service on the solar panels of the Mir space station.
Other sources of problems for structures subjected to outer space are erosion and redeposition of the materials by sputtering caused by fast atoms and micrometeoroids. Another major concern, though of non-corrosive kind, is material fatigue caused by cyclical heating and cooling and associated thermal expansion mechanical stresses. | 0 | Metallurgy |
In contact with ambient air, liquid aluminium reacts with the oxygen and form an oxide film layer (gamma-AlO). This layer becomes thicker with time. When molten aluminium is disturbed, this oxide film gets mixed inside the melt. | 0 | Metallurgy |
Sintering is generally considered successful when the process reduces porosity and enhances properties such as strength, electrical conductivity, translucency and thermal conductivity. In some special cases, sintering is carefully applied to enhance the strength of a material while preserving porosity (e.g. in filters or catalysts, where gas absorbency is a priority). During the firing process, atomic diffusion drives powder surface elimination in different stages, starting at the formation of necks between powders to final elimination of small pores at the end of the process.
The driving force for densification is the change in free energy from the decrease in surface area and lowering of the surface free energy by the replacement of solid-vapor interfaces. It forms new but lower-energy solid-solid interfaces with a net decrease in total free energy. On a microscopic scale, material transfer is affected by the change in pressure and differences in free energy across the curved surface. If the size of the particle is small (and its curvature is high), these effects become very large in magnitude. The change in energy is much higher when the radius of curvature is less than a few micrometers, which is one of the main reasons why much ceramic technology is based on the use of fine-particle materials.
The ratio of bond area to particle size is a determining factor for properties such as strength and electrical conductivity. To yield the desired bond area, temperature and initial grain size are precisely controlled over the sintering process. At steady state, the particle radius and the vapor pressure are proportional to (p) and to (p), respectively.
The source of power for solid-state processes is the change in free or chemical potential energy between the neck and the surface of the particle. This energy creates a transfer of material through the fastest means possible; if transfer were to take place from the particle volume or the grain boundary between particles, particle count would decrease and pores would be destroyed. Pore elimination is fastest in samples with many pores of uniform size because the boundary diffusion distance is smallest. during the latter portions of the process, boundary and lattice diffusion from the boundary become important.
Control of temperature is very important to the sintering process, since grain-boundary diffusion and volume diffusion rely heavily upon temperature, particle size, particle distribution, material composition, and often other properties of the sintering environment itself. | 0 | Metallurgy |
Offset – the total dimension that the shutter will travel outwards when moved from the closed to the open position. The offset is typically the distance from the face of the casement to the outermost surface of the structure.
The offset is developed in shutter hardware by selection of a pintle made to "stand off" the casement a given distance – the shutter hinge has a sharp bend which moves the hinge barrel away from the face of the shutter at a distance to match the pintle standoff.
When measuring offset, it is critical to allow for irregularities in construction. Because brick and stone openings are rarely plumb and or perfectly flat, it is typical to use the greatest dimension and allow about ½" cushion. If the offset is too small the shutters will not open fully. If the offset is too great, the shutter will function well but sit off of the wall.
Standoff – The pintle standoff is the distance from the face of the casement to the mid-line of the pintle pin. The hinge standoff is the distance from the face of the shutter to the center-line of the hinge barrel. Adding the pintle standoff to the hinge standoff results in the total offset.
Virtually all commercially available shutter hardware is provided with matching standoff on the hinge and pintle. This assumes that the face of the shutter will lie on the same plane as the casement with the shutter in the closed position.
Hinge and pintle standoffs can be custom made to a user's situation. This eases installation and insures proper shutter function.
Throw – This is the measure of the horizontal movement of the edge of the shutter as it swings from the open to the closed position and varies greatly between hinge styles. If too little throw, the open shutter will cover the window molding. Too much throw and too much brick or siding shows between the open shutter edge and the window frame. Proper throw insures that the shutter will comfortably "frame" the window – not obstruct or detract from window detail. | 0 | Metallurgy |
Normally, the Wnt signaling pathway leads to stabilization of β-catenin through inactivation of a protein complex containing the tumor suppressors APC and Axin. This destruction complex normally triggers β-catenin phosphorylation, inducing its degradation. De-regulation of the autocrine Wnt signaling pathway via mutations in APC and Axin have been linked to activation of various types of human cancer. Genetic alterations that lead to de-regulation of the autocrine Wnt pathway result in transactivation of epidermal growth factor receptor (EGFR) and other pathways, in turn contributing to proliferation of tumor cells. In colorectal cancer, for example, mutations in APC, axin, or β-catenin promote β-catenin stabilization and transcription of genes encoding cancer-associated proteins. Furthermore, in human breast cancer, interference with the de-regulated Wnt signaling pathway reduces proliferation and survival of cancer. These findings suggest that interference with Wnt signaling at the ligand-receptor level may improve the effectiveness of cancer therapies. | 1 | Gene expression + Signal Transduction |
RNA sequencing is a next-generation sequencing technology; as such it requires only a small amount of RNA and no previous knowledge of the genome. It allows for both qualitative and quantitative analysis of RNA transcripts, the former allowing discovery of new transcripts and the latter a measure of relative quantities for transcripts in a sample.
The three main steps of sequencing transcriptomes of any biological samples include RNA purification, the synthesis of an RNA or cDNA library and sequencing the library. The RNA purification process is different for short and long RNAs. This step is usually followed by an assessment of RNA quality, with the purpose of avoiding contaminants such as DNA or technical contaminants related to sample processing. RNA quality is measured using UV spectrometry with an absorbance peak of 260 nm. RNA integrity can also be analyzed quantitatively comparing the ratio and intensity of 28S RNA to 18S RNA reported in the RNA Integrity Number (RIN) score. Since mRNA is the species of interest and it represents only 3% of its total content, the RNA sample should be treated to remove rRNA and tRNA and tissue-specific RNA transcripts.
The step of library preparation with the aim of producing short cDNA fragments, begins with RNA fragmentation to transcripts in length between 50 and 300 base pairs. Fragmentation can be enzymatic (RNA endonucleases), chemical (trismagnesium salt buffer, chemical hydrolysis) or mechanical (sonication, nebulisation). Reverse transcription is used to convert the RNA templates into cDNA and three priming methods can be used to achieve it, including oligo-DT, using random primers or ligating special adaptor oligos. | 1 | Gene expression + Signal Transduction |
Applications of quorum quenching that have been exploited by humans include the use of AHL-degrading bacteria in aquacultures to limit the spread of diseases in aquatic populations of fish, mollusks and crustaceans. This technique has also been translated to agriculture, to restrict the spread of pathogenic bacteria that use quorum sensing in plants. Anti-biofouling is another process that exploits quorum quenching bacteria to mediate the dissociation of unwanted biofilms aggregating on wet surfaces, such as medical devices, transportation infrastructure and water systems. Quorum quenching is recently studied for the control of fouling and emerging contaminants in electro membrane bioreactors (eMBRs) for the advanced treatment of wastewater. Extracts of several traditional medicinal herbs display quorum quenching acivity, and have potential antibacterial applications. | 1 | Gene expression + Signal Transduction |
SMA actuators are typically actuated electrically by Joule heating. If the SMA is used in an environment where the ambient temperature is uncontrolled, unintentional actuation by ambient heating may occur. | 0 | Metallurgy |
Performance, maintenance, service life, and recovery costs from recycling are factors that determine the cost effectiveness of building components. While copper's initial cost is higher than some other architectural metals, it usually does not need to be replaced during the life of a building. Due to its durability, low maintenance, and ultimate salvage value, the additional cost for copper may be insignificant over the life of a roofing system.
Copper roofing is considerably less expensive than lead, slate, or hand-made clay tiles. Its costs are comparable with zinc, stainless steel, aluminium and even some clay and concrete tiles when considering overall roofing costs (including structure).
Some studies indicate that copper is a more cost-effective material on a life cycle basis than other roof materials with a lifetime of 30 years or more. A European study comparing roofing costs of copper with other metals, concrete and clay tiles, slate, and bitumen found that in the medium to long-term (for lives of 60 to 80 years and 100 years and over), copper and stainless steel were the most cost effective roofing materials of all materials examined.
Installation techniques such as prefabrication, in-situ machine forming, mechanized seaming, and the long-strip system help to reduce the installation costs of copper roofing. By lowering installation costs, these techniques permit designers to specify copper into a wider array of building types, not just large prestigious projects as had been common in the past.
Since scrap copper retains much of its primary value, copper's life cycle costs are reduced when accounting for its salvage value. For more information, see Recyclability section in this article. | 0 | Metallurgy |
In genetics, a super-enhancer is a region of the mammalian genome comprising multiple enhancers that is collectively bound by an array of transcription factor proteins to drive transcription of genes involved in cell identity. Because super-enhancers are frequently identified near genes important for controlling and defining cell identity, they may thus be used to quickly identify key nodes regulating cell identity.
Enhancers have several quantifiable traits that have a range of values, and these traits are generally elevated at super-enhancers. Super-enhancers are bound by higher levels of transcription-regulating proteins and are associated with genes that are more highly expressed. Expression of genes associated with super-enhancers is particularly sensitive to perturbations, which may facilitate cell state transitions or explain sensitivity of super-enhancer—associated genes to small molecules that target transcription. | 1 | Gene expression + Signal Transduction |
Flotation can be performed in rectangular or cylindrical mechanically agitated cells or tanks, flotation columns, Jameson Cells or deinking flotation machines. Classified by the method of air absorption manner, it is fair to state that two distinct groups of flotation equipment have arisen:pneumatic and mechanical machines. Generally pneumatic machines give a low-grade concentrate and little operating troubles.
Mechanical cells use a large mixer and diffuser mechanism at the bottom of the mixing tank to introduce air and provide mixing action. Flotation columns use air spargers to introduce air at the bottom of a tall column while introducing slurry above. The countercurrent motion of the slurry flowing down and the air flowing up provides mixing action. Mechanical cells generally have a higher throughput rate, but produce material that is of lower quality, while flotation columns generally have a low throughput rate but produce higher quality material.
The Jameson cell uses neither impellers nor spargers, instead combining the slurry with air in a downcomer where high shear creates the turbulent conditions required for bubble particle contacting. | 0 | Metallurgy |
Hellmut Fischmeister was elected as a foreign member of the Royal Swedish Academy of Engineering Sciences in 1975. In 1981, he was elected as a corresponding member of the Austrian Academy of Sciences and was a member of the Academia Europaea since 1989. In 1995, he became a full member of the mathematical-natural sciences class of the Austrian Academy of Sciences.
* 1969: Knight of the Royal Order of the North Star
* 1991: Honorary doctorate from the Royal Institute of Technology in Stockholm
* 1992: Honorary doctorate from Graz University of Technology
* 1997: Order of Merit of the Federal Republic of Germany, Cross of Merit 1st Class
* 2007: Honorary doctorate from the University of Leoben
* 2010: Austrian Cross of Honour for Science and Art, 1st class
* 2010: Honorary member of the German Materials Society (Deutsche Gesellschaft für Materialkunde) | 0 | Metallurgy |
The mitochondrial targeting signal also known as presequence is a 10-70 amino acid long peptide that directs a newly synthesized protein to the mitochondria. It is found at the N-terminus end consists of an alternating pattern of hydrophobic and positively charged amino acids to form what is called an amphipathic helix. Mitochondrial targeting signals can contain additional signals that subsequently target the protein to different regions of the mitochondria, such as the mitochondrial matrix or inner membrane. In plants, an N-terminal signal (or transit peptide) targets to the plastid in a similar manner. Like most signal peptides, mitochondrial targeting signals and plastid specific transit peptides are cleaved once targeting is complete. Some plant proteins have an N-terminal transport signal that targets both organelles often referred to as dual-targeted transit peptide. Approximately 5% of total organelle proteins are predicted to be dual-targeted however the specific number could be higher considering the variable degree of accumulation of passenger proteins in both organelles. The targeting specificity of these transit peptides depends on many factors including net charge and affinity between transit peptides and organelle transport machinery. | 1 | Gene expression + Signal Transduction |
The world's first iron pillar was the Iron pillar of Delhi—erected at the times of Chandragupta II Vikramaditya (375–413), often considered as one of the finest pieces of ancient metallurgy. The swords manufactured in Indian workshops find written mention in the works of Muhammad al-Idrisi (flourished 1154). Indian Blades made of Damascus steel found their way into Persia. European scholars—during the 14th century—studied Indian casting and metallurgy technology.
Indian metallurgy under the Mughal emperor Akbar (reign: 1556–1605) produced excellent small firearms. Gommans (2002) holds that Mughal handguns were probably stronger and more accurate than their European counterparts.
Srivastava & Alam (2008) comment on Indian coinage of the Mughal Empire (established: April 21, 1526 - ended: September 21, 1857) during Akbar's regime:
Statues of Nataraja and Vishnu were cast during the reign of the imperial Chola dynasty (200–1279) in the 9th century. The casting could involve a mixture of five metals: copper, zinc, tin, gold, and silver.
Considered great feat in metallurgy, the hollow, Seamless, celestial globe was invented in Kashmir by Ali Kashmiri ibn Luqman in 998 AH (1589-90 CE), and twenty other such globes were later produced in Lahore and Kashmir during the Mughal Empire. These Indian metallurgists pioneered the method of lost-wax casting, and disguised plugs, in order to produce these globes. | 0 | Metallurgy |
The nines scale is also used in other contexts, such as describing the purity of gases. The purity of a gas is an indication of the ratio of it to other gases in its mixture, as measured by volume. Thus, a high purity refers to a low amount of other gases, or impurities. Gases of higher purity are in many contexts considered to be of better quality and are usually more expensive.
The purity of a gas is generally expressed as a grade prefixed with the letter N (rather than postfixed), indicating the "number of nines" in the percentage or decimal fraction. For example, a N2.0 gas is 99% (two nines) pure and 1% impurities by volume; a N6.0 gas is 99.9999% (six nines) pure, with 1 part per million (1 ppm or 1 vpm, volume per million) impurities.
Intermediate values indicate the digit following the last nine. For example, N4.6 estimates a purity level of 99.996% (four nines followed by a six). An alternative representation uses the common logarithm: for example, a gas which is 99.97% pure would be described as N3.5, since log(0.03%) = −3.523. | 0 | Metallurgy |
Kinesis, like a taxis or tropism, is a movement or activity of a cell or an organism in response to a stimulus (such as gas exposure, light intensity or ambient temperature).
Unlike taxis, the response to the stimulus provided is non-directional. The animal does not move toward or away from the stimulus but moves at either a slow or fast rate depending on its "comfort zone." In this case, a fast movement (non-random) means that the animal is searching for its comfort zone while a slow movement indicates that it has found it. | 1 | Gene expression + Signal Transduction |
A nonsense mutation in one gene of an operon prevents the translation of subsequent genes in the unit. This effect is called mutational polarity. A common cause is the absence of the mRNA corresponding to the subsequent (distal) parts of the unit. Suppose that there are Rho-dependent terminators within the transcription unit, that is, before the terminator that usually is used. Normally these earlier terminators are not used, because the ribosome prevents Rho from reaching RNA polymerase. But a nonsense mutation releases the ribosome, so that Rho is free to attach to and/or move along the RNA, enabling it to act on RNA polymerase at the terminator. As a result, the enzyme is released, and the distal regions of the transcription unit are never transcribed. | 1 | Gene expression + Signal Transduction |
With the rise of the environmentalist movement has also come an increased appreciation for social justice, and mining has showed similar trends lately. Societies located near potential mining sites are at increased risk to be subjected to injustices as their environment is affected by the changes made to mined lands—either public or private—that could eventually lead to problems in social structure, identity, and physical health (Franks 2009). Many have argued that by cycling mine power through local citizens, this disagreement can be alleviated, since both interest groups would have shared and equal voice and understanding in future goals. However, it is often difficult to match corporate mining interests with local social interests, and money is often a deciding factor in the successes of any disagreements. If communities are able to feel like they have a valid understanding and power in issues concerning their local environment and society, they are more likely to tolerate and encourage the positive benefits that come with mining, as well as more effectively promote alternative methods to heap leach mining using their intimate knowledge of the local geography (Franks 2009). | 0 | Metallurgy |
Due to the increased demand for iron for casting cannons, the blast furnace came into widespread use in France in the mid 15th century.
The direct ancestor of those used in France and England was in the Namur region, in what is now Wallonia (Belgium). From there, they spread first to the Pays de Bray on the eastern boundary of Normandy and from there to the Weald of Sussex, where the first furnace (called Queenstock) in Buxted was built in about 1491, followed by one at Newbridge in Ashdown Forest in 1496. They remained few in number until about 1530 but many were built in the following decades in the Weald, where the iron industry perhaps reached its peak about 1590. Most of the pig iron from these furnaces was taken to finery forges for the production of bar iron.
The first British furnaces outside the Weald appeared during the 1550s, and many were built in the remainder of that century and the following ones. The output of the industry probably peaked about 1620, and was followed by a slow decline until the early 18th century. This was apparently because it was more economic to import iron from Sweden and elsewhere than to make it in some more remote British locations. Charcoal that was economically available to the industry was probably being consumed as fast as the wood to make it grew.
The first blast furnace in Russia opened in 1637 near Tula and was called the Gorodishche Works. The blast furnace spread from there to central Russia and then finally to the Urals. | 0 | Metallurgy |
The PPM family, which includes PP2C and pyruvate dehydrogenase phosphatase, are enzymes with Mn/Mg metal ions that are resistant to classic inhibitors and toxins of the PPP family. Unlike most PPPs, PP2C exists in only one subunit but, like PTPs, it displays a wide variety of structural domains that confer unique functions. In addition, PP2C does not seem to be evolutionarily related to the major family of Ser/Thr PPs and has no sequence homology to ancient PPP enzymes. The current assumption is that PPMs evolved separately from PPPs but converged during evolutionary development. | 1 | Gene expression + Signal Transduction |
Native ironwork in the Northwest Coast has been found in places like the Ozette Indian Village Archeological Site, where iron chisels and knives were discovered. These artifacts seem to have been crafted around 1613, based on the dendrochronological analysis of associated pieces of wood in the site, and were made out of drift iron from Asian (specifically Japanese) shipwrecks, which were swept by the Kuroshio Current towards the coast of North America.
The tradition of working with Asian drift iron was well-developed in the Northwest before European contact, and was present among several native peoples from the region, including the Chinookan peoples and the Tlingit, who seem to have had their own specific word for the metallic material, which was transcribed by Frederica De Laguna as gayES. The wrecking of Japanese and Chinese vessels in the North Pacific basin was fairly common, and the iron tools and weaponry they carried provided the necessary materials for the development of the local ironwork traditions among the Northwestern Pacific Coast peoples,
although there were also other sources of iron, like that from meteorites, which was occasionally worked using stone anvils. | 0 | Metallurgy |
Paired receptors are pairs or clusters of receptor proteins that bind to extracellular ligands but have opposing activating and inhibitory signaling effects. Traditionally, paired receptors are defined as homologous pairs with similar extracellular domains and different cytoplasmic regions, whose genes are located together in the genome as part of the same gene cluster and which evolved through gene duplication. Homologous paired receptors often, but not always, have a shared ligand in common. More broadly, pairs of receptors have been identified that exhibit paired functional behavior - responding to a shared ligand with opposing intracellular signals - but are not closely homologous or co-located in the genome. Paired receptors are highly expressed in the cells of the immune system, especially natural killer (NK) and myeloid cells, and are involved in immune regulation. | 1 | Gene expression + Signal Transduction |
Besides the above-mentioned two most commonly used family of techniques, a wide range of protocols were developed to measure chemotactic activity. Some of them are only qualitative, like aggregation tests, where small pieces of agar or filters are placed onto a slide and accumulation of cells around is measured.
In another semiquantitative technique, cells are overlaid the test substance and changes in opalescence of the originally cell-free compartment is recorded during the incubation time.
The third frequently used qualitative technique is the T-maze and its adaptations for microplates. In the original version, a container drilled in a peg is filled with cells. Then the peg is twisted and the cells get contact with two other containers filled with different substances. The incubation is stopped by resetting the peg and the cell number is counted from the containers.
Also, lately, microfluidic devices have been used more and more frequently to test quantitatively, and precisely, for chemotaxis. | 1 | Gene expression + Signal Transduction |
One of the most commonly quoted potential causes of WECs is hydrogen embrittlement caused by an unstable equilibrium between material, mechanical, and chemical aspects, which occurs when hydrogen atoms diffuse into the bearing steel, causing micro-cracks to form. Hydrogen can come from a variety of sources, including the hydrocarbon lubricant or water contamination, and it is often used in laboratory tests to reproduce WECs. Mechanisms behind the generation of hydrogen from lubricants was attributed to three primary factors contributing: decomposition of lubricants through catalytic reactions with a fresh metal surface, breakage of molecular chains within the lubricant due to shear on the sliding surface, and thermal decomposition of lubricants caused by heat generation during sliding. Hydrogen generation is influenced by lubricity, wear width, and the catalytic reaction of a fresh metal surface. | 0 | Metallurgy |
Vat leaching involves contacting material, which has usually undergone size reduction and classification, with leach solution in large vats. | 0 | Metallurgy |
Particles of refractory material in contact with aluminium can detach and become inclusions. We can find graphite inclusions (C), alumina inclusions (alpha-AlO), CaO, SiO, …
After some time, graphite refractory in contact with aluminium will react to create aluminum carbides (harder and more detrimental inclusions).
In aluminium alloy containing magnesium, the magnesium reacts with some refractories to create rather big and hard inclusions similar to spinels.
Unreacted refractory particles can originate from the degradation of refractory materials which comes in contact with the melt. | 0 | Metallurgy |
Translational regulation of MITF is still an unexplored area with only two peer-reviewed papers (as of 2019) highlighting the importance. During glutamine starvation of melanoma cells ATF4 transcripts increases as well as the translation of the mRNA due to eIF2α phosphorylation. This chain of molecular events leads to two levels of MITF suppression: first, ATF4 protein binds and suppresses MITF transcription and second, eIF2α blocks MITF translation possibly through the inhibition of eIF2B by eIF2α.
MITF can also be directly translationally modified by the RNA helicase DDX3X. The 5 UTR of MITF contains important regulatory elements (IRES) that is recognized, bound and activated by DDX3X. Although, the 5 UTR of MITF only consists of a nucleotide stretch of 123-nt, this region is predicted to fold into energetically favorable RNA secondary structures including multibranched loops and asymmetric bulges that is characteristics of IRES elements. Activation of this cis-regulatory sequences by DDX3X promotes MITF expression in melanoma cells. | 1 | Gene expression + Signal Transduction |
CTCF binds to the consensus sequence CCGCGNGGNGGCAG (in IUPAC notation). This sequence is defined by 11 zinc finger motifs in its structure. CTCF's binding is disrupted by CpG methylation of the DNA it binds to. On the other hand, CTCF binding may set boundaries for the spreading of DNA methylation. In recent studies, CTCF binding loss is reported to increase localized CpG methylation, which reflected another epigenetic remodeling role of CTCF in human genome.
CTCF binds to an average of about 55,000 DNA sites in 19 diverse cell types (12 normal and 7 immortal) and in total 77,811 distinct binding sites across all 19 cell types.
CTCF's ability to bind to multiple sequences through the usage of various combinations of its zinc fingers earned it the status of a “multivalent protein”. More than 30,000 CTCF binding sites have been characterized. The human genome contains anywhere between 15,000 and 40,000 CTCF binding sites depending on cell type, suggesting a widespread role for CTCF in gene regulation. In addition CTCF binding sites act as nucleosome positioning anchors so that, when used to align various genomic signals, multiple flanking nucleosomes can be readily identified. On the other hand, high-resolution nucleosome mapping studies have demonstrated that the differences of CTCF binding between cell types may be attributed to the differences in nucleosome locations. Methylation loss at CTCF-binding site of some genes has been found to be related to human diseases, including male infertility. | 1 | Gene expression + Signal Transduction |
The successful operation and development of the demonstration copper ISASMELT, and the degree of interest shown in the new process by the global smelting community, gave MIM Holdings sufficient confidence to license the ISASMELT technology to external companies, so an agreement under which MIM could incorporate the Sirosmelt lance into ISASMELT technology was signed with the CSIRO in 1989. | 0 | Metallurgy |
Archaeometallurgical experimentation typically takes place in controlled laboratories or tries to remain as authentic as possible by being conducted using only the materials and facilities that were available to the subjects whose technology is trying to be reconstructed. Regardless of location though, the experimentation is always conducted under a different mindset outside the context of what was originally intended. A constant problem in any type of experimental archaeology is the cultural distance between the archaeologist and the individual who originally was involved with the metallurgy. This difference in mindset may lead to misunderstandings in the processes behind the metallurgy. Second to this, not all experiments are successful and it is hard to determine if this is the fault of the techniques used or the individual conducting the experiment. | 0 | Metallurgy |
The untranslated regions of mRNA became a subject of study as early as the late 1970s, after the first mRNA molecule was fully sequenced. In 1978, the 5 UTR of the human gamma-globin mRNA was fully sequenced. In 1980, a study was conducted on the 3 UTR of the duplicated human alpha-globin genes. | 1 | Gene expression + Signal Transduction |
In bacteria, termination of RNA transcription can be rho-dependent or rho-independent. The former relies on the rho factor, which destabilizes the DNA-RNA heteroduplex and causes RNA release. The latter, also known as intrinsic termination, relies on a palindromic region of DNA. Transcribing the region causes the formation of a "hairpin" structure from the RNA transcription looping and binding upon itself. This hairpin structure is often rich in G-C base-pairs, making it more stable than the DNA-RNA hybrid itself. As a result, the 8 bp DNA-RNA hybrid in the transcription complex shifts to a 4 bp hybrid. These last 4 base pairs are weak A-U base pairs, and the entire RNA transcript will fall off the DNA.
Transcription termination in eukaryotes is less well understood than in bacteria, but involves cleavage of the new transcript followed by template-independent addition of adenines at its new 3′ end, in a process called polyadenylation. | 1 | Gene expression + Signal Transduction |
For many years after the new art deco fronted building was opened in 1939 the work was carried out in laboratories fronting on Euston Street, London, NW1. These included three parallel four-story blocks of laboratories and offices with the basements being used for the heaviest equipment and for storage of samples. The Euston Street building was extended to the right of the main entrance making the address 81–103 Euston Street, with the laboratories behind being in Regnart Buildings and Euston Buildings which fronted on Stephenson Way. The extension was opened on 13 May 1959 by Sir Alexander Fleck. In the mid-1950s Prince Philip, Duke of Edinburgh toured all departments.
The laboratories were grouped in specialist sections, including analytical chemistry, corrosion, creep testing, electroplating, fatigue testing, general metallurgy, information library, mechanical testing, melting and casting, members liaison, metallography, metal working, physics (X-ray crystallography), and spectrography.
The laboratories were an excellent training ground both for assistants who studied for their qualifications part-time and for recent graduates from universities. As such members found that staff could be ideal recruits for industrial work. There were 150–200 staff and the average time for researchers to stay was about three years and they could then be found in industries in Britain and worldwide. From the late 1930s to the 1960s through the war and then post-war recovery the Director was Mr G. L. Bailey with Miss E. M. (Helen) Hills as his secretary. | 0 | Metallurgy |
Sodium dithiophosphate is the salt with the formula NaPSO. It is usually supplied as the hydrated solid or as an aqueous solution together with other thiophosphates such as sodium monothiophosphate and sodium trithiophosphate. It is a colorless compound, but commercial samples can appear dark owing to the presence of impurities. It is used to facilitate the isolation of molybdenum from its ores. | 0 | Metallurgy |
In common with recovery and recrystallisation, growth phenomena can be separated into continuous and discontinuous mechanisms. In the former the microstructure evolves from state A to B (in this case the grains get larger) in a uniform manner. In the latter, the changes occur heterogeneously and specific transformed and untransformed regions may be identified. Abnormal or discontinuous grain growth is characterised by a subset of grains growing at a high rate and at the expense of their neighbours and tends to result in a microstructure dominated by a few very large grains. In order for this to occur the subset of grains must possess some advantage over their competitors such as a high grain boundary energy, locally high grain boundary mobility, favourable texture or lower local second-phase particle density. | 0 | Metallurgy |
When the pre-mRNA has been transcribed from the DNA, it includes several introns and exons. (In nematodes, the mean is 4–5 exons and introns; in the fruit fly Drosophila there can be more than 100 introns and exons in one transcribed pre-mRNA.) The exons to be retained in the mRNA are determined during the splicing process. The regulation and selection of splice sites are done by trans-acting splicing activator and splicing repressor proteins as well as cis-acting elements within the pre-mRNA itself such as exonic splicing enhancers and exonic splicing silencers.
The typical eukaryotic nuclear intron has consensus sequences defining important regions. Each intron has the sequence GU at its 5 end. Near the 3 end there is a branch site. The nucleotide at the branchpoint is always an A; the consensus around this sequence varies somewhat. In humans the branch site consensus sequence is yUnAy. The branch site is followed by a series of pyrimidines – the polypyrimidine tract – then by AG at the 3' end.
Splicing of mRNA is performed by an RNA and protein complex known as the spliceosome, containing snRNPs designated U1, U2, U4, U5, and U6 (U3 is not involved in mRNA splicing). U1 binds to the 5' GU and U2, with the assistance of the U2AF protein factors, binds to the branchpoint A within the branch site. The complex at this stage is known as the spliceosome A complex. Formation of the A complex is usually the key step in determining the ends of the intron to be spliced out, and defining the ends of the exon to be retained. (The U nomenclature derives from their high uridine content).
The U4,U5,U6 complex binds, and U6 replaces the U1 position. U1 and U4 leave. The remaining complex then performs two transesterification reactions. In the first transesterification, 5 end of the intron is cleaved from the upstream exon and joined to the branch site A by a 2,5-phosphodiester linkage. In the second transesterification, the 3 end of the intron is cleaved from the downstream exon, and the two exons are joined by a phosphodiester bond. The intron is then released in lariat form and degraded. | 1 | Gene expression + Signal Transduction |
Julian Simon was a senior fellow at the Cato Institute and a professor of business and economics. In his book The Ultimate Resource 2 (first printed in 1981 and reprinted in 1998), he extensively criticizes the notion of "peak resources", and uses copper as one example. He argues that, even though "peak copper" has been a persistent scare since the early 20th century, "known reserves" grew at a rate that outpaced demand, and the price of copper was not rising but falling over the long run. For example, even though world production of copper in 1950 was only one-eighth of what it was in the early 2000s, known reserves were also much lower at the time – around 100 million metric tons – making it appear that the world would run out of copper in 40 to 50 years at most.
Simon's own explanation for this development is that the very notion of known reserves is deeply flawed, as it does not take into account changes in mining profitability. As richer mines are exhausted, developers turn their attention to poorer sources of the element and eventually develop cheap methods of extracting it, raising known reserves. Thus, for example, copper was so abundant 5000 years ago, occurring in pure form as well as in highly concentrated copper ores, that prehistoric peoples were able to collect and process it with very basic technology. As of the early 21st century, copper is commonly mined from ores that contain 0.3–0.6% copper by weight. Yet, despite the material being far less widespread, the cost of, for example, a copper pot was vastly lower in the late 20th century than 5000 years ago. | 0 | Metallurgy |
Transforming growth factor beta-1-induced transcript 1 protein is a protein that in humans is encoded by the TGFB1I1 gene. Often put together with and studied alongside TGFB1I1 is the mouse homologue HIC-5 ( Hydrogen Peroxide-Inducible Clone-5). As the name suggests, TGFB1I1 is an induced form of the larger family of TGFB1. Studies suggest TGFB1I1 plays a role in processes of cell growth, proliferation, migration, differentiation and senescence. TGFB1I1 is most localized at focal adhesion complexes of cells, although it may be found active in the cytosol, nucleus and cell membrane as well. | 1 | Gene expression + Signal Transduction |
Galvanic corrosion is the electrochemical erosion of metals. Corrosion occurs when two dissimilar metals are in contact with each other in the presence of an electrolyte, such as salt water. This forms a galvanic cell, with hydrogen gas forming on the more noble (less active) metal. The resulting electrochemical potential then develops an electric current that electrolytically dissolves the less noble material. A concentration cell can be formed if the same metal is exposed to two different concentrations of electrolyte. | 0 | Metallurgy |
Splicing occurs in all the kingdoms or domains of life, however, the extent and types of splicing can be very different between the major divisions. Eukaryotes splice many protein-coding messenger RNAs and some non-coding RNAs. Prokaryotes, on the other hand, splice rarely and mostly non-coding RNAs. Another important difference between these two groups of organisms is that prokaryotes completely lack the spliceosomal pathway.
Because spliceosomal introns are not conserved in all species, there is debate concerning when spliceosomal splicing evolved. Two models have been proposed: the intron late and intron early models (see intron evolution). | 1 | Gene expression + Signal Transduction |
All eukaryotes use G proteins for signaling and have evolved a large diversity of G proteins. For instance, humans encode 18 different G proteins, 5 G proteins, and 12 G proteins. | 1 | Gene expression + Signal Transduction |
Recognition of stop codons in bacteria have been associated with the so-called tripeptide anticodon, a highly conserved amino acid motif in RF1 (PxT) and RF2 (SPF). Even though this is supported by structural studies, it was shown that the tripeptide anticodon hypothesis is an oversimplification. | 1 | Gene expression + Signal Transduction |
The HNF6 subfamily members contain a cut-homeodomain (ONECUT) bind to DNA as monomers.
* HNF6α/OC-1/ONECUT1 ()
* HNF6β/OC-2/ONECUT2 () | 1 | Gene expression + Signal Transduction |
TIVA tags are created initially via solid-phase synthesis with the cell-penetrating peptide conjugated afterwards. The functional components of the tag can be summarized as following:
* Biotin: binds to streptavidin beads for tag isolation.
* Cy3 fluorophore: used to validated cleavage of photocleavable linker. If cleaved, cell will appear green upon exposure to 514 nm light.
* Cy5 fluorophore: used to validate uptake into cells. If uptake is successful, and if Cy5 is not yet cleaved from the TIVA tag, energy from a 514 nm light will be absorbed via FRET from Cy3 to Cy5, where cells that have taken up the TIVA will appear red.
* PolyU 18-mer oligonucleotide: used to bind mRNA via complementary base pairing of their polyadenylated tails. Before cleavage of photocleavable linkers, it is caged by complementary base pairing to two polyA 7-mer oligonucleotides.
* PolyA 7-mer oligonucleotides: before the cleavage of photocleavable linkers, 2 polyA 7-mer molecules conjugate to polyU oligonucleotides to cage the TIVA tag, and thus prevent it from binding mRNA molecules. After photocleavable linkers are cleaved, the melting temperature decreases from 59 °C to less than 25 °C, leading to the disassociation of the PolyA 7-mer oligonucleotides from the TIVA tag.
* Photocleavable linker: links and stabilizes Cy5 fluorophore and PolyA 7-mer oligonucleotides to the TIVA tag. It is cleaved upon photoactivation.
* Cell-penetrating peptide CPP: guides the TIVA tag through cell membranes into tissues. It is linked to the TIVA tag by a disulphide bond that is cleaved once exposed to extracellular environment. | 1 | Gene expression + Signal Transduction |
The releasable pool is located in the active zone and is bound directly to the presynaptic membrane. It is stabilized by proteins within the active zone and bound to the presynaptic membrane by SNARE proteins. These vesicles are ready to release by a single action potential and are replenished by vesicles from the reserve pool. The releasable pool is sometimes subdivided into the readily releasable pool and the releasable pool. | 1 | Gene expression + Signal Transduction |
A Walloon forge (or Walloon process) is a type of finery forge that decarbonizes pig iron into wrought iron.
The process was conceived in the Liège region, and from there extended to France, then England around the end of the 15th century. Louis de Geer brought it to Roslagen in Sweden at the beginning of the 17th century, with Walloon blacksmiths.
The Walloon process spread to Sweden in the Uppland province north of Stockholm, where it was used to produce a specific kind of wrought iron called oregrounds iron. | 0 | Metallurgy |
CpG islands are commonly 200 to 2000 base pairs long, have a C:G base pair content >50%, and have frequent 5 → 3 CpG sequences. About 70% of human promoters located near the transcription start site of a gene contain a CpG island.
Promoters located at a distance from the transcription start site of a gene also frequently contain CpG islands. The promoter of the DNA repair gene ERCC1, for instance, was identified and located about 5,400 nucleotides upstream of its coding region. CpG islands also occur frequently in promoters for functional noncoding RNAs such as microRNAs and Long non-coding RNAs (lncRNAs). | 1 | Gene expression + Signal Transduction |
John U. Nef, an expert on Renaissance economics, described liquation as ‘even more important than the invention of the printing press’ for the development of industry during this period. It increased production of silver on a massive scale. Between 1460 and 1530, the output of silver increased as much as fivefold in central Europe. This had a secondary effect of lowering the costs of producing copper at a time when its demand had increased due to the needs of the brassmaking industry, and the use of copper on ships and roofs. Lead production also received a boost, indeed the lack of lead available held the liquation process back until a large lead-bearing seam was discovered at Tarnowitz in Poland.
Liquation triggered an increase in mining operations, and a new class of wealthy merchants clamoured to participate. Some of the wealthiest merchants in Europe invested in mining, including the French Royal Banker Jacques Coeur and the powerful Medici family of Florence. However, most of the funds came from merchants in neighbouring towns. For example, the burghers of Nuremberg funded mines in the mountains of Bohemia and the Harz.
Many new copper and silver mines sprang up. A mine at Jáchymov (Joachimstal) in the Ore Mountains was so successful that a coin called tolar was created, which led to the term, dollar. Others of note included Schneeberg, and Annaberg (also in the Ore Mountains), Schwaz, in the valley of the Inn, and at Neusohl in Hungary. The new mining wealth allowed some of the largest mines of previous centuries to reopen, such as the silver-bearing lead and copper mines of Rammelsberg. These old mines had previously been abandoned due to flooding, collapses, lack of technology, or simply a lack of money. Now shafts could be sunk deeper and water more efficiently drained, so miners could work seams once out of reach.
Liquation-based wealth helped build roads between mining and processing regions, and financed improvements to mining technology. Thus its influence went beyond just increasing silver and copper production. It helped revive the economy of large parts of Europe, and the mining of other metals such as iron and mercury. | 0 | Metallurgy |
Tom filed at least five patents in the UK and two in the US. He invented and patented the technology used at Thornaby as the Whitwell Heating Stove. Over two hundred stoves were installed in over 70 furnaces around the globe. He also patented a continuous brick-burning kiln and a more efficient fire grate. | 0 | Metallurgy |
(AD 900–1500)
Utilitarian and ceremonial objects; objects of personal adornment
#Chiapa de Corzo, Chiapas
#El Paredón, Chiapas
#Polol, Guatemala
#Santa Rita Corozal, Belize
#Nojpetén, Guatemala
#Tikal, Guatemala
#Yaxhá, Guatemala
#Palenque, Chiapas
#Wild Cane Cay, Belize
#Lamanai, Belize | 0 | Metallurgy |
Platinum Metals Review was abstracted and indexed by:
* Chemical Abstracts
* Chemical Engineering and Biotechnology Abstracts
* Compendex
* Corrosion Abstracts
* Current Contents/Physical, Chemical & Earth Sciences
* Environment Abstracts
* Metals Abstracts/METADEX
* Metal Finishing Abstracts
* Science Citation Index Expanded
* Scopus
* World Textile Abstracts | 0 | Metallurgy |
The Parkes process, patented in 1850 uses molten zinc. Zinc is not miscible with lead and when the two molten metals are mixed the zinc separates and floats to the top carrying only some 2% lead. However silver preferentially dissolves in zinc, so the zinc that floats to the top carries a significant proportion of the silver. The melt is then cooled until the zinc solidifies and the zinc crust is skimmed off. The silver is then recovered by volatalising the zinc. The Parkes process largely replaced the Pattinson process, except where the lead contained insufficient silver, in which case the Pattinson process provided a method to enrich it in silver to about 40 to 60 ounces per ton, at which concentration it could be treated using the Parkes' process. | 0 | Metallurgy |
Honey bees (Apis mellifera) also use quorum sensing to make decisions about new nest sites. Large colonies reproduce through a process called swarming, in which the queen leaves the hive with a portion of the workers to form a new nest elsewhere. After leaving the nest, the workers form a swarm that hangs from a branch or overhanging structure. This swarm persists during the decision-making phase until a new nest site is chosen.
The quorum sensing process in honey bees is similar to the method used by Temnothorax ants in several ways. A small portion of the workers leave the swarm to search out new nest sites, and each worker assesses the quality of the cavity it finds. The worker then returns to the swarm and recruits other workers to her cavity using the honey bee waggle dance. However, instead of using a time delay, the number of dance repetitions the worker performs is dependent on the quality of the site. Workers that found poor nests stop dancing sooner, and can, therefore, be recruited to the better sites. Once the visitors to a new site sense that a quorum number (usually 10–20 bees) has been reached, they return to the swarm and begin using a new recruitment method called piping. This vibration signal causes the swarm to take off and fly to the new nest location. In an experimental test, this decision-making process enabled honey bee swarms to choose the best nest site in four out of five trials. | 1 | Gene expression + Signal Transduction |
CKLF like MARVEL transmembrane domain-containing 1 (i.e. CMTM1), formerly termed chemokine-like factor superfamily 1 (i.e. CKLFSF1), has 23 known isoforms, the CMTM1-v1 to CMTM1-v23 proteins. Protein isoforms are variant products that are made by alternative splicing of a single gene. The gene for these isoforms, CMTM1 (formerly termed CKLFSF1), is located in band 22 on the long (i.e. "q") arm of chromosome 16. The CMTM1 gene and its 23 isoforms belong to the CKLF-like MARVEL transmembrane domain-containing family of structurally and functionally related genes and proteins. CMTM1 (isoforms not specified) proteins are weakly express in a wide range of normal tissues but are far more highly expressed in normal testes as well as the malignant cells of certain types of cancer.
Studies have reported that the levels of CMTM1 (typically the CMTM1–v17 isoform) are more highly expressed in breast, kidney, lung, ovary, liver (i.e. hepatocellular carcinoma), and salivary gland adenoid cystic carcinoma malignant tissues than the nearby normal tissues of these respective organs. According to the Human Protein Atlas, higher levels of CMTM1 expression in hepatocellular carcinoma tissues are associated with shorter survival times. Another study found that the levels of CMTM1 mRNA (which directs the production of CMTM1 protein) were higher in stomach cancer compared to nearby normal stomach tissues. And, studies of glioblastoma found no significant difference between the levels of CMTM1 in this brain tumor's tissues versus nearby normal brain tissues but higher levels of tumor tissue CMTM1 were associated with poorer prognoses. In addition, the forced overexpression of CMTM1 in cultured glioblastoma cell lines increased their proliferation and invasiveness. These findings suggest that CMTM1 proteins may act to promote the cited cancers and support further studies to determine if these proteins contribute to the development and/or progression of the cited cancers, can be used as markers of disease severity and/or prognosis, or are targets for treating these cancers.
In contrast to the findings in the cancers just cited, cell culture studies indicated that the forced overexpression of the CMTM1-v5 isoform induced apoptosis (i.e. cell death due to the activation of cell death-inducing signaling pathways) in two types of lymphoma cell lines, Jurkat cells (a human T cell leukemia cell line) and Raji cells (a human non-Hodgkins lymphoma cell line). Simple addition of CMTM1-v5 protein to cultures of Daudi or Ramos cells (both are Burkitts lymphoma cell lines) or Jurkat cells likewise caused these cells to become apoptotic. Various other cultured hematological tumor cell lines had no such response to the CMTM1-v5 protein. Finally, the injection of CMTM1-v5 into mice containing Raji cell tumors in a xenotransplantation model of cancer inhibited the spread of these tumors and prolonged the survival of the mice. These findings suggest that CMTM1-v5 protein may act to suppress certain types of lymphoma in humans and support initial studies to define the CMTM1-v5 levels in the malignant cells of humans with these lymphomas. Further studies are also needed to determine the basis for the CMTM1 proteins promoting actions in the cited cancers versus' suppressing actions in the cited lymphomas. | 1 | Gene expression + Signal Transduction |
(Also see: Eyespot apparatus)
*Channelrhodopsin: in unicellular algae, mediates phototaxis
*Chlamyopsin and volvoxopsin
*Flavoproteins | 1 | Gene expression + Signal Transduction |
Living organisms produce retinal by irreversible oxidative cleavage of carotenoids.
For example:
:beta-carotene + O → 2 retinal,
catalyzed by a beta-carotene 15,15-monooxygenase or a beta-carotene 15,15-dioxygenase.
Just as carotenoids are the precursors of retinal, retinal is the precursor of the other forms of vitamin A. Retinal is interconvertible with retinol, the transport and storage form of vitamin A:
:retinal + NADPH + H retinol + NADP
:retinol + NAD retinal + NADH + H,
catalyzed by retinol dehydrogenases (RDHs) and alcohol dehydrogenases (ADHs).
Retinol is called vitamin A alcohol or, more often, simply vitamin A. Retinal can also be oxidized to retinoic acid:
:retinal + NAD + HO → retinoic acid + NADH + H (catalyzed by RALDH)
:retinal + O + HO → retinoic acid + HO (catalyzed by retinal oxidase),
catalyzed by retinal dehydrogenases also known as retinaldehyde dehydrogenases (RALDHs) as well as retinal oxidases.
Retinoic acid, sometimes called vitamin A acid, is an important signaling molecule and hormone in vertebrate animals. | 1 | Gene expression + Signal Transduction |
Oxide dispersion strengthening is based on incoherency of the oxide particles within the lattice of the material. Coherent particles have a continuous lattice plane from the matrix to the particles whereas incoherent particles do not have this continuity and therefore both lattice planes end at the interface. This mismatch in interfaces results in a high interfacial energy, which impedes dislocation. The oxide particles instead are stable in the matrix, which helps prevent creep. Particle stability implies little dimensional change, embrittlement, effects on properties, stable particle spacing, and general resistance to change at high temperatures.
Since the oxide particles are incoherent, dislocations can only overcome the particles by climb. If instead the particles are semi-coherent or coherent with the lattice, dislocations can simply cut the particles by a more favourable process that requires less energy called dislocation glide or by Orowan bowing between particles, both of which are athermal mechanisms. Dislocation climb is a diffusional process, which is less energetically favourable, and mostly occurs at higher temperatures that provide enough energy to advance via the addition and removal of atoms. Because the particles are incoherent, glide mechanisms alone are not enough and the more energetically exhausting climb process is dominant, meaning that dislocations are stopped more effectively. Climb can occur either at the particle-dislocation interface (local climb) or by overcoming multiple particles at once (general climb). In local climb, the part of the dislocation that is between two particles stays in the glide plane while the rest of the dislocation is climbing along the surface of the particle. For general climb, the dislocations all come out the glide plane. General climb requires less energy because the mechanism decreases the dislocation line length which reduces the elastic strain energy and therefore is the common climb mechanism. For γ’ volume fractions of 0.4 to 0.6 in nickel-based alloys, the threshold stress for local climb is only about 1.25 to 1.40 times higher than general climb.
Dislocations are not limited to either all local or all general climb as the path that requires less energy is taken. Cooperative climb is an example of a more nuanced mechanism where a dislocation travels around a group of particles rather than climbing past each particle individually. McLean stated that the dislocation is most relaxed when climbing over multiple particles because of the skipping of some of the abrupt interfaces between segments in the glide plane to segments that travel along the particle surface.
The presence of incoherent particles introduces a threshold stress (σ), since an additional stress will have to be applied for the dislocations to move past the oxides by climb. After overcoming a particle by climb, dislocations can remain pinned at the particle-matrix interface with an attractive phenomenon called interfacial pinning, which requires additional threshold stress to free a dislocation out of this pinning, which must be overcome for plastic deformation to occur. This detachment phenomenon is a result of the interaction between the particle and the dislocation where total elastic strain energy is reduced. Schroder and Arzt explain that the additional stress required is due to the relaxation caused by the reduction in the stress field as the dislocation climbs and accommodates the shear traction. The following equations represent the strain rate and stress as a result of oxide introduction.
Strain Rate:
Threshold Shear Stress: | 0 | Metallurgy |
The mold, protozoan, and coelenterate mitochondrial code and the mycoplasma/spiroplasma code (translation table 4) is the genetic code used by various organisms, in some cases with slight variations, notably the use of UGA as a tryptophan codon rather than a stop codon. | 1 | Gene expression + Signal Transduction |
Methods that screen protein–protein interactions in the living cells.
Bimolecular fluorescence complementation (BiFC) is a technique for observing the interactions of proteins. Combining it with other new techniques, dual expression recombinase based (DERB) methods can enable the screening of protein–protein interactions and their modulators.
The yeast two-hybrid screen investigates the interaction between artificial fusion proteins inside the nucleus of yeast. This approach can identify the binding partners of a protein without bias. However, the method has a notoriously high false-positive rate, which makes it necessary to verify the identified interactions by co-immunoprecipitation. | 1 | Gene expression + Signal Transduction |
The genetic code was once believed to be universal: a codon would code for the same amino acid regardless of the organism or source. However, it is now agreed that the genetic code evolves, resulting in discrepancies in how a codon is translated depending on the genetic source. For example, in 1981, it was discovered that the use of codons AUA, UGA, AGA and AGG by the coding system in mammalian mitochondria differed from the universal code. Stop codons can also be affected: in ciliated protozoa, the universal stop codons UAA and UAG code for glutamine. The following table displays these alternative codons. | 1 | Gene expression + Signal Transduction |
The regulation of Ler and its transcript, ler, is complex and many-fold. The plasmid encoded regulator (per) directly activates the region of the LEE1 operon which encodes Ler. Integration host factor is also a direct activator of ler and binds upstream of its promoter.
Jeannette Barba and her colleagues at the National Autonomous University of Mexico elucidated a positive regulatory loop between Ler, ler, GrlA, and grlRA. GrlA is also a LEE encoded regulator of the LEE pathogenicity island. They found that GrlA activates ler, and that Ler activates grlRA indicating a loop of activation wherein a protein product activates a transcript whose protein product activates the transcript of the original protein. Ler activates grlRA only if H-NS is present, this is not the case for GrlA activation of ler.
Quorum sensing plays a role in Ler regulation. LuxS is an important protein involved in quorum sensing, particularly in the synthesis of autoinducer molecules. Quorum-sensing E. coli regulator A (QseA) is found in LuxS systems and activates transcription of ler. Fis, a nucleoid associated protein essential for EPEC's ability to form attaching and effacing lesions, partly acts through activation of Ler expression. BipA, a ribosomal binding GTPase and prolific regulator of EPEC virulence, transcriptionally regulates Ler from an upstream position where it also regulates other genes.
The Ler protein also represses its own transcript on the LEE1 operon through DNA looping which prevents RNA polymerase from completing transcription. | 1 | Gene expression + Signal Transduction |
For blast furnaces, direct reduction corresponds to the reduction of oxides by the carbon in the coke. However, in practice, direct reduction only plays a significant role in the final stage of iron reduction in a blast furnace, by helping to reduce wustite (FeO) to iron. In this case, the chemical reaction can be trivially described as follows:
FeO + C → Fe + CO consuming 155,15 kJ/mol
However, "in the solid state, there is virtually no reaction in the absence of gases, even between finely ground iron ore and coal powders. In other words, it seems certain that the reaction takes place via gases". This means that direct reduction most probably corresponds to the following chain of reactions:
FeO + CO → Fe + CO producing 17,45 kJ/mol (reduction by CO)
CO + C ⇌ 2 CO consuming 172,45 kJ/mol (Boudouard reaction) | 0 | Metallurgy |
The syndetome location within the somite is determined by FGF secreted from the center of the myotome (a collection of embryonic tissue that develops into skeletal muscle)- the FGF then induces the adjacent anterior and posterior sclerotome (a collection of embryonic tissue that develops into the axial skeleton) to adopt a tendon cell fate. This ultimately places future scleraxis-expressing cells between the two tissue types they will ultimately join.
Scleraxis expression will be seen throughout the entire sclerotome (rather than just the sclerotome directly anterior and posterior to the myotome) with an overexpression of FGF8, demonstrating that all sclerotome cells are capable of expressing scleraxis in response to FGF signaling. While the FGF interaction has been shown to be necessary for scleraxis expression, it is still unclear as to whether the FGF signaling pathway directly induces the syndetome to secrete scleraxis, or indirectly through a secondary signaling pathway. Most likely, the syndetomal cells, through careful reading of the FGF concentration (coming from the myotome), can precisely determine their location and begin expressing scleraxis. Much of embryonic development follows this model of inducing specific cell fates through the reading of surrounding signaling molecule concentration gradients. | 1 | Gene expression + Signal Transduction |
Although the targets of CK2 are predominantly nucleus-based the protein itself is localized to both the nucleus and cytoplasm. Casein kinase 2 activity has been reported to be activated following Wnt signaling pathway activation. A Pertussis toxin-sensitive G protein and Dishevelled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of CK2. Further studies need to be done on the regulation of this protein due to the complexity of CK2 function and localization.
Phosphorylation of CK2α T344 has been shown to inhibit its proteasomal degradation and support binding to Pin1. O-GlcNAcylation at S347 antagonizes this phosphorylation and accelerates CK2α degradation. O-GlcNAcylation of CK2α has also been shown to alter the phosphoproteome, notably including many chromatin regulators such as HDAC1, HDAC2, and HCFC1. | 1 | Gene expression + Signal Transduction |
The first widescale use of VCIs can be traced to Shell's patent for dicyclohexylammonium nitrite (DICHAN), which was eventually commercialized as VPI 260. DICHAN was used extensively by the US military to protect a wide variety of metallic components from corrosion via various delivery systems, VCI powder, VCI paper, VCI solution, VCI slushing compound, etc.
Safety and health concerns as well as inherent limitations has led to the abandonment of DICHAN as a VCI. At present, commercial VCI compounds are typically salts of moderately strong bases and weak volatile acids. The typical bases are amines and the acids are carbonic, nitrous and carboxylic. | 0 | Metallurgy |
Some miRNAs target the messenger RNAs for DNA methyltransferase genes DNMT1, DNMT3A and DNMT3B, whose gene products are needed for initiating and stabilizing promoter methylations. As summarized in three reviews, miRNAs miR-29a, miR-29b and miR-29c target DNMT3A and DNMT3B; miR-148a and miR-148b target DNMT3B; and miR-152 and miR-301 target DNMT1. In addition, miR-34b targets DNMT1 and the promoter of miR-34b itself is hypermethylated and under-expressed in the majority of prostate cancers. When expression of these microRNAs is altered, they may also be a source of the hyper/hypo-methylation of the promoters of protein-coding genes in cancers. | 1 | Gene expression + Signal Transduction |
CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a genetic engineering technique that allows for precise editing of the genome. One application of CRISPR is gene knockout, which involves disabling or "knocking out" a specific gene in an organism.
The process of gene knockout with CRISPR involves three main steps: designing a guide RNA (gRNA) that targets a specific location in the genome, delivering the gRNA and a Cas9 enzyme (which acts as a molecular scissors) to the target cell, and then allowing the cell to repair the cut in the DNA. When the cell repairs the cut, it can either join the cut ends back together, resulting in a non-functional gene, or introduce a mutation that disrupts the gene's function.
This technique can be used in a variety of organisms, including bacteria, yeast, plants, and animals, and it allows scientists to study the function of specific genes by observing the effects of their absence. CRISPR-based gene knockout is a powerful tool for understanding the genetic basis of disease and for developing new therapies.
It is important to note that CRISPR-based gene knockout, like any genetic engineering technique, has the potential to produce unintended or harmful effects on the organism, so it should be used with caution. The coupled Cas9 will cause a double stranded break in the DNA. Following the same principle as zinc-fingers and TALENs, the attempts to repair these double stranded breaks often result in frameshift mutations that result in an nonfunctional gene. Non invasive CRISPR-Cas9 technology has successfully knocked out a gene associated in depression and anxiety in mice, being the first successful delivery passing through the blood–brain barrier to enable gene modification. | 1 | Gene expression + Signal Transduction |
*Stress corrosion cracking Stress corrosion (NACE term)
*Corrosion fatigue
*Caustic cracking (ASTM term)
*Caustic embrittlement (ASM term)
*Sulfide stress cracking (ASM, NACE term)
*Stress-accelerated Corrosion (NACE term)
*Hydrogen stress cracking (ASM term)
*Hydrogen-assisted stress corrosion cracking (ASM term) | 0 | Metallurgy |
PI3K/ AKT/mTOR pathway is a central regulator of ovarian cancer. PIM kinases are over expressed in many types of cancers and they also contribute to the regulation of ovarian cancer. PIM are directly and indirectly found to activate mTOR and its upstream effectors like AKT. Besides, PIM kinases can cause phosphorylation of IRS, which can alter PI3K. This indicates the close interaction of PIM with PI3K/ AKT/mTOR cascade and its components. Similarly, AKT has also been reported to perform the BAD phosphorylation in OC cells. PIM and the PI3K/AKT/mTOR network both can inhibit the P21 and P27 expressions in OC cells. These data suggest a strong possibility of interaction and relevance of PIM kinases and the PI3K/AKT/mTOR network in the regulation of ovarian cancer. However, targeting this pathway in ovarian cancer has been challenging with several trials failing to achieve sufficient clinical benefit. | 1 | Gene expression + Signal Transduction |
Experimental reconstruction of tools used in prehistoric mining is often written about in conjunction with the tools use after the process of firesetting. The experimental mining tool assemblage are primarily made up of hammerstones and antler picks that are reconstructed using willow and hazel sticks, rawhide, and hemp string to implement various hafting techniques and methods of utilization. | 0 | Metallurgy |
Froth flotation is applied to a wide range of separations. An estimated 1B tons of materials are processed in this manner annually. | 0 | Metallurgy |
In materials science, recrystallization is a process by which deformed grains are replaced by a new set of defect-free grains that nucleate and grow until the original grains have been entirely consumed. Recrystallization is usually accompanied by a reduction in the strength and hardness of a material and a simultaneous increase in the ductility. Thus, the process may be introduced as a deliberate step in metals processing or may be an undesirable byproduct of another processing step. The most important industrial uses are softening of metals previously hardened or rendered brittle by cold work, and control of the grain structure in the final product. Recrystallization temperature is typically 0.3–0.4 times the melting point for pure metals and 0.5 times for alloys. | 0 | Metallurgy |
The final loaded carbon is removed from the machinery and extracted with a hot alkaline solution of cyanide. The elute solution passes through an electrowinning cell where the gold metal is deposited. The solution then passes back through the loaded carbon, extracting more gold and other metals. This process continues until the carbon has been stripped of its metals.
The cathodes (wire wool, now plated with gold and other metals) are removed and placed in sulfuric, hydrochloric, or nitric acid. The acid burns off the wire wool and other metals such as copper, and leaves a sediment of gold and a solution of acid and dissolved silver. The acid and silver are drained off, after which the gold sediment is washed with water numerous times. | 0 | Metallurgy |
The enhancers comprising super-enhancers share the functions of enhancers, including binding transcription factor proteins, looping to target genes, and activating transcription. Three notable traits of enhancers comprising super-enhancers are their clustering in genomic proximity, their exceptional signal of transcription-regulating proteins, and their high frequency of physical interaction with each other. Perturbing the DNA of enhancers comprising super-enhancers showed a range of effects on the expression of cell identity genes, suggesting a complex relationship between the constituent enhancers. Super-enhancers separated by tens of megabases cluster in three-dimensions inside the nucleus of mouse embryonic stem cells.
High levels of many transcription factors and co-factors are seen at super-enhancers (e.g., CDK7, BRD4, and Mediator).
This high concentration of transcription-regulating proteins suggests why their target genes tend to be more highly expressed than other classes of genes. However, housekeeping genes tend to be more highly expressed than super-enhancer—associated genes.
Super-enhancers may have evolved at key cell identity genes to render the transcription of these genes responsive to an array of external cues. The enhancers comprising a super-enhancer can each be responsive to different signals, which allows the transcription of a single gene to be regulated by multiple signaling pathways. Pathways seen to regulate their target genes using super-enhancers include Wnt, TGFb, LIF, BDNF, and NOTCH. The constituent enhancers of super-enhancers physically interact with each other and their target genes over a long range sequence-wise.
Super-enhancers that control the expression of major cell surface receptors with a crucial role in the function of a given cell lineage have also been defined. This is notably the case for B-lymphocytes, the survival, the activation and the differentiation of which rely on the expression of membrane-form immunoglobulins (Ig). The Ig heavy chain locus super-enhancer is a very large (25kb) cis-regulatory region, including multiple enhancers and controlling several major modifications of the locus (notably somatic hypermutation, class-switch recombination and locus suicide recombination). | 1 | Gene expression + Signal Transduction |
In 1709, at Coalbrookdale in Shropshire, England, Abraham Darby began to fuel a blast furnace with coke instead of charcoal. Cokes initial advantage was its lower cost, mainly because making coke required much less labor than cutting trees and making charcoal, but using coke also overcame localized shortages of wood, especially in Britain and on the Continent. Metallurgical grade coke will bear heavier weight than charcoal, allowing larger furnaces. A disadvantage is that coke contains more impurities than charcoal, with sulfur being especially detrimental to the irons quality. Coke's impurities were more of a problem before hot blast reduced the amount of coke required and before furnace temperatures were hot enough to make slag from limestone free flowing. (Limestone ties up sulfur. Manganese may also be added to tie up sulfur.)
Coke iron was initially only used for foundry work, making pots and other cast iron goods. Foundry work was a minor branch of the industry, but Darbys son built a new furnace at nearby Horsehay, and began to supply the owners of finery forges with coke pig iron for the production of bar iron. Coke pig iron was by this time cheaper to produce than charcoal pig iron. The use of a coal-derived fuel in the iron industry was a key factor in the British Industrial Revolution. Darbys original blast furnace has been archaeologically excavated and can be seen in situ at Coalbrookdale, part of the Ironbridge Gorge Museums. Cast iron from the furnace was used to make girders for the world's first cast iron bridge in 1779. The Iron Bridge crosses the River Severn at Coalbrookdale and remains in use for pedestrians. | 0 | Metallurgy |
JAK inhibitors are used for the treatment of atopic dermatitis and rheumatoid arthritis. They are also being studied in psoriasis, polycythemia vera, alopecia, essential thrombocythemia, ulcerative colitis, myeloid metaplasia with myelofibrosis and vitiligo. Examples are tofacitinib, baricitinib, upadacitinib and filgotinib.
In 2014 researchers discovered that oral JAK inhibitors, when administered orally, could restore hair growth in some subjects and that applied to the skin, effectively promoted hair growth. | 1 | Gene expression + Signal Transduction |
The protein encoded by this gene is a member of the STAT protein family. In response to cytokines and growth factors, STAT family members are phosphorylated by the receptor associated kinases, and then form homo- or heterodimers that translocate to the cell nucleus where they act as transcription activators. In response to IFN, this protein forms a complex with STAT1 and IFN regulatory factor family protein p48 (IRF9) and form ISGF-3 (IFN-stimulated gene factor-3), in which this protein acts as a transactivator, but lacks the ability to bind DNA directly. The protein mediates innate antiviral activity. Mutations in this gene result in Immunodeficiency 44. ISGF-3 proceeds the activation of genes via the IFN-stimulated response element (ISRE). ISRE-driven genes include Ly-6C, the double-stranded RNA kinase (PKR), 2´ to 5´ oligoadenylate synthase (OAS), MX and potentially MHC class I. Transcription adaptor P300/CBP (EP300/CREBBP) has been shown to interact specifically with this protein, which is thought to be involved in the process of blocking IFN-alpha response by adenovirus.
STAT2 knockout mice are unresponsive to type I IFN and extremely vulnerable to viral infection. They indicate the loss of the type I IFN autocrine loop and several defects in macrophages and T cell responses. Stat2-/- cells show differences in the biological response to IFN-α. | 1 | Gene expression + Signal Transduction |
#Motilin
#Neurotensin
#Substance P
#Somatostatin
#Bombesin
#Serotonin
#Angiotensin
#Nitric Oxide
#Kinins
#Histamine | 1 | Gene expression + Signal Transduction |
The unexpected fall in 2011 of a heavy light fixture from the ceiling of the Big Dig vehicular tunnel in Boston revealed that corrosion had weakened its support. Improper use of aluminium in contact with stainless steel had caused rapid corrosion in the presence of salt water. The electrochemical potential difference between stainless steel and aluminium is in the range of 0.5 to 1.0V, depending on the exact alloys involved, and can cause considerable corrosion within months under unfavorable conditions. Thousands of failing lights would have to be replaced, at an estimated cost of $54 million. | 0 | Metallurgy |
In 1973, the Freeport-McMoRan Copper and Gold ("Freeport") smelter at Miami, Arizona, installed a 51 MW electric furnace at its Miami smelter. The decision was based on a long-term electrical power contract with the Salt River Project that provided the company with a very low rate for electricity. This contract expired in 1990 and the resulting increase in electricity prices prompted the owners of the smelter, Cyprus Miami Mining Corporation ("Cyprus"), to seek alternative smelting technologies for lower operating costs.
The technologies evaluated included:
* Contop flame cyclone reactor
* Inco flash furnace
* ISASMELT
* Mitsubishi furnace
* Noranda reactor
* Outokumpu flash furnace
* Teniente furnace.
The Contop, Inco, Mitsubishi and Outokumpu processes "were all eliminated primarily because of their high dust levels, high capital costs and poor adaptability to the existing facility". The Teniente converter was ruled out because it required the use of the electric furnace for partial smelting. The Noranda reactor was not selected "because of its high refractory wear and its poor adaptability to the existing plant due to the handling of the reactor slag". ISASMELT was chosen as the preferred technology and a licence agreement was signed with MIM in October 1990. The major factor in the decision to select the ISASMELT technology was the ability to fit it into the existing plant and to maximise the use of existing equipment and infrastructure, while the major disadvantage was seen to be the risks associated with scaling up the technology from the Mount Isa demonstration plant.
The Miami copper ISASMELT furnace was designed to treat 590,000 t/y (650,000 short tons per year) of copper concentrate, a treatment rate that was constrained by the capacity of the sulfuric acid plant used to capture the sulfur dioxide from the smelter's waste gases. The existing electric furnace was converted from smelting duties to a slag cleaning furnace and providing matte surge capacity for the converters. The ISASMELT furnace was commissioned on 11 June 1992 and in 2002 treated over 700,000 t/y of concentrate. The modernisation of the Miami smelter cost an estimated US$95 million.
In 1993, the Cyprus Minerals Company merged with AMAX to form the Cyprus Amax Minerals company, which was in turn taken over by the Phelps Dodge Corporation in late 1999. After the take-over, Phelps Dodge closed its Hidalgo and Chino smelters. Phelps Dodge was acquired by Freeport in 2006.
The Miami smelter is one of only two remaining operating copper smelters in the United States, down from 16 in 1979. | 0 | Metallurgy |
High-temperature corrosion is a mechanism of corrosion that takes place when gas turbines, diesel engines, furnaces or other machinery come in contact with hot gas containing certain contaminants. Fuel sometimes contains vanadium compounds or sulfates, which can form low melting point compounds during combustion. These liquid melted salts are strongly corrosive to stainless steel and other alloys normally resistant with respect to corrosion at high temperatures. Other types of high-temperature corrosion include high-temperature oxidation, sulfidation, and carbonization. High temperature oxidation and other corrosion types are commonly modeled using the Deal-Grove model to account for diffusion and reaction dynamics. | 0 | Metallurgy |
One aspect of RNA silencing to consider is its possible off-target affects, toxicity, and delivery methods. If RNA silencing is to become a conventional drug, it must first pass the typical ethical issues of biomedicine. Using risk-benefit analysis, researchers can determine whether RNA silencing conforms to ethical ideologies such as nonmaleficence, beneficence, and autonomy.
There is a risk of creating infection-competent viruses that could infect non-consenting people. There is also a risk of affecting future generations based on these treatments. These two scenarios, in respect to autonomy, is possible unethical. At this moment, unsafe delivery methods and unintended aspects of vector viruses add to the argument against RNA silencing.
In terms of off-target effects, siRNA can induce innate interferon responses, inhibit endogenous miRNAs through saturation, and may have complementary sequences to other non-target mRNAs. These off-targets could also have target up-regulations such as oncogenes and antiapoptotic genes. The toxicity of RNA silencing is still under review as there are conflicting reports.
RNA silencing is quickly developing, because of that, the ethical issues need to be discussed further. With the knowledge of general ethical principles, we must continuously perform risk-benefit analysis. | 1 | Gene expression + Signal Transduction |
Microarrays can be manufactured in different ways, depending on the number of probes under examination, costs, customization requirements, and the type of scientific question being asked. Arrays from commercial vendors may have as few as 10 probes or as many as 5 million or more micrometre-scale probes. | 1 | Gene expression + Signal Transduction |
Mechanistic target of rapamycin has been shown to interact with:
* ABL1,
* AKT1,
* IGF-IR,
* InsR,
* CLIP1,
* EIF3F
* EIF4EBP1,
* FKBP1A,
* GPHN,
* KIAA1303,
* PRKCD,
* RHEB,
* RICTOR,
* RPS6KB1,
* STAT1,
* STAT3,
* Two-pore channels: TPCN1; TPCN2, and
* UBQLN1. | 1 | Gene expression + Signal Transduction |
Chemical and electrical synapses are two ways of synaptic transmission.
* In a chemical synapse, electrical activity in the presynaptic neuron is converted (via the activation of voltage-gated calcium channels) into the release of a chemical called a neurotransmitter that binds to receptors located in the plasma membrane of the postsynaptic cell. The neurotransmitter may initiate an electrical response or a secondary messenger pathway that may either excite or inhibit the postsynaptic neuron. Chemical synapses can be classified according to the neurotransmitter released: glutamatergic (often excitatory), GABAergic (often inhibitory), cholinergic (e.g. vertebrate neuromuscular junction), and adrenergic (releasing norepinephrine). Because of the complexity of receptor signal transduction, chemical synapses can have complex effects on the postsynaptic cell.
* In an electrical synapse, the presynaptic and postsynaptic cell membranes are connected by special channels called gap junctions that are capable of passing an electric current, causing voltage changes in the presynaptic cell to induce voltage changes in the postsynaptic cell. In fact, gap junctions facilitate the direct flow of electrical current without the need for neurotransmitters, as well as small molecules like calcium. Thus, the main advantage of an electrical synapse is the rapid transfer of signals from one cell to the next.
* Mixed chemical electrical synapses are synaptic sites that feature both a gap junction and neurotransmitter release. This combination allows a signal to have both a fast component (electrical) and a slow component (chemical).
The formation of neural circuits in nervous systems, appears to heavily depend on the crucial interactions between chemical and electrical synapses. Thus, these interactions govern the generation of synaptic transmission. Synaptic communication is distinct from an ephaptic coupling, in which communication between neurons occurs via indirect electric fields. An autapse is a chemical or electrical synapse that forms when the axon of one neuron synapses onto dendrites of the same neuron. | 1 | Gene expression + Signal Transduction |
Ambient-temperature molten salts (also known as ionic liquids) are present in the liquid phase at standard conditions for temperature and pressure. Examples of such salts include N-ethylpyridinium bromide and aluminium chloride mix, discovered in 1951, and ethylammonium nitrate discovered by Paul Walden. Other ionic liquids take advantage of asymmetrical quaternary ammonium cations like alkylated imidazolium ions, and large, branched anions like the bistriflimide ion. | 0 | Metallurgy |
Most gilding methods are additive: they deposit gold that was not there before onto the surface of an object. By contrast, depletion gilding is a subtractive process whereby material is removed to increase the purity of gold that is already present on an object's surface.
In depletion gilding, other metals are etched away from the surface of an object composed of a gold alloy by the use of acids or salts, often in combination with heat. Since no gold is added, only an object made of an alloy that already contains gold can be depletion gilded.
Depletion gilding relies on the fact that gold is highly resistant to oxidation or corrosion by most common chemicals, whereas many other metals are not. Depletion gilding is most often used to treat alloys of gold with copper or silver. Unlike gold, both copper and silver readily react with a variety of chemicals. For example, nitric acid is effective as an etching agent for both copper and silver. Under the proper circumstances, even ordinary table salt will react with either metal.
The object to be gilded is coated, immersed, or packed in a suitable acid or salt, and usually heated to speed the process. These chemicals then attack the metallic copper and silver in the objects surface, transforming it to various copper and silver compounds. The resulting copper and silver compounds can be removed from the objects surface by a number of processes. Washing, chemical leaching, heating, or even physical absorption by porous materials such as brick dust have all been used historically. Meanwhile, the relatively inert gold is left unaffected. The result is a thin layer of nearly pure gold on the surface of the original object.
There is no well-defined minimum gold content required to successfully depletion gild an object. However, the less gold that is present, the more other material must be etched away to produce the desired surface appearance. In addition, the removal of the other metals usually leaves the surface covered with microscopic voids and pits. This can make the surface soft and "spongy" with a dull or matte appearance. This effect becomes more pronounced as more base metal is removed. For this reason, most depletion gilded objects are burnished to make their surfaces more durable and give them a more attractive polished finish.
Like other gilding processes, depletion gilding provides a way to produce the appearance of pure gold without its disadvantages: its cost and rarity, and its softness and denseness. By producing a layer of gold over a layer of copper or other metal, objects can be made that are lighter, sturdier, and cheaper while still appearing to be nearly pure gold. | 0 | Metallurgy |
AMPP offers individual training and certification programs. Many are merged programs that originated as competing programs under the former NACE and SSPC organizations. Other programs are still being administered under the legacy NACE or SSPC frameworks until the merger is complete. | 0 | Metallurgy |
* Alcan Lynemouth Aluminium Smelter, powered by the coal-fired Lynemouth Power Station in North East England, ceased production in 2012, demolished in 2018.
* Anglesey Aluminium, powered by Wylfa nuclear power station in north-west Wales, closed in 2013, with redevelopment of the site announced in 2022.
* The Valco aluminium smelter in Ghana, powered by the Akosombo Hydroelectric Project
* Fjarðaál in Iceland, powered by the Kárahnjúkar Hydropower Plant
* Jharsuguda in Orissa, India, to be powered by its own coal-fired power station.
* Aluminerie Alouette in Sept-Îles, Québec, powered by the Churchill Falls Hydro Electric project.
* Alba Smelter in Bahrain, powered by its own four power stations with a total generating capacity of . | 0 | Metallurgy |
Woods metal, also known as Lipowitzs alloy or by the commercial names Cerrobend, Bendalloy, Pewtalloy and MCP 158, is a metal alloy that is useful for soldering and making custom metal parts, but its vapor is toxic to touch or breathe. The alloy is named for Barnabas Wood, who invented and patented the alloy in 1860. It is a eutectic, fusible alloy of 50% bismuth, 26.7% lead, 13.3% tin, and 10% cadmium by mass. It has a melting point of approximately . | 0 | Metallurgy |
Advances in massively parallel sequencing has led to the development of RNA-Seq technology, that enables a whole transcriptome shotgun approach to characterize and quantify gene expression. Unlike microarrays, which need a reference genome and transcriptome to be available before the microarray itself can be designed, RNA-Seq can also be used for new model organisms whose genome has not been sequenced yet. | 1 | Gene expression + Signal Transduction |
In the United States, the Environmental Protection Agency has published pollution control regulations for smelters.
* Air pollution standards under the Clean Air Act
* Water pollution standards (effluent guidelines) under the Clean Water Act.
The RMI Conformant Smelter Program
As conflict mineral use grows, numerous initiatives have been launched to counteract the problem. They encourage responsible mineral sourcing practices in regions under circumstances of conflict, human rights abuse, or labour exploitation.
The Responsible Mineral Initiative, RMI, has developed a set of ideals and guidelines for smelter, including the Conformant Smelter Program. The program is a third-party audit and certification program that assesses the performance of smelters in the responsible sourcing of minerals. This program adheres to the Organization for Economic Co-operation and Development, OECD, guidelines. Published in the OECD Due Diligence Guidance for Responsible Supply Chains of Minerals from Conflict-Affected and High-Risk Areas. The OECD is a body focused on policies for bettering global practices.
The focus of the program is evaluating smelters on:
*Sourcing practices: Demonstrating sourced minerals do not contribute to active conflict, human rights issues, or environmental damage
*Due Diligence: Establishing a due diligence process to mitigate risks in the supply chain
*Transparency: Information being transparent about their sourcing
*Environmental and social performance: Minimizing the environmental impact and respecting workers' rights
Smelters that meet the RMI standards gain recognition on the RMI Conformant Smelter & Refiner Lists.
This is not the only program regulating the smelting industry, additional auditing programs include:
*The London Bullion Market Association, LBMA, focuses on gold, silver, platinum, and palladium. With successful smelters gaining recognition on the Good Suppliers List.
*Responsible Jewellery Council, RJC, promotes responsible practices in the jewellery supply chain. Successful smelters gaining recognition on the RJC members registry.
Similarly, to the RMI Conformant Smelter Program these entities comply with OECD guidelines and promote ethical and environmental supply chain management. However, the named organizations have varying additional guidelines therefore the only cross recognized audits with the RMI are:
*LBMA Responsible Gold Guidance
*RMI Responsible Minerals Assurance Process Gold Standard
*RJC Chain-of-Custody (CoC) Standard (provision 1 only)
*RJC Code of Practices (COP) Standard (provision 7 only) | 0 | Metallurgy |
Direct reduction is the fraction of iron oxide reduction that occurs in a blast furnace due to the presence of coke carbon, while the remainder - indirect reduction - consists mainly of carbon monoxide from coke combustion.
It should also be noted that many non-ferrous oxides are reduced by this type of reaction in a blast furnace. This reaction is therefore essential to the operation of historical processes for the production of non-ferrous metals by non-steel blast furnaces (i.e. blast furnaces dedicated to the production of ferromanganese, ferrosilicon, etc., which have now disappeared).
Direct-reduction steelmaking processes that bring metal oxides into contact with carbon (typically those based on the use of hard coal or charcoal) also exploit this chemical reaction. In fact, at first glance, many of them seem to use only this reaction. Processes that historically competed with blast furnaces, such as the Catalan forge, have been assimilated into this reaction. But modern direct reduction processes are often based on the exclusive use of reducing gases: in this case, their name takes on the exact opposite meaning to that of the chemical reaction. | 0 | Metallurgy |
The effects of anaerobic corrosion are evident when evaluating the safety of chemical waste disposal. Currently, the permanent disposal of nuclear waste is commonly in deep geological repositories (DGR) that use copper coating to prevent metal corrosion. In the DGR, four major types of corrosion are expected to occur, including oxygen-driven, radiation-influenced, anaerobic, and microbiologically-influenced corrosion. Of these, the most notable process is the microbiologically-influenced corrosion in terms of the magnitude of corrosion. The ability of microorganisms such as SRB to survive in a wide range of environments also lends to their relevance when considering the threat of corrosion to permanent chemical waste disposal. | 0 | Metallurgy |
Promoters are DNA segments near the 5' end of the gene where transcription begins. They are the sites where RNA polymerase binds to initiate RNA synthesis. Every gene has a noncoding promoter.
Regulatory elements are sites that control the transcription of a nearby gene. They are almost always sequences where transcription factors bind to DNA and these transcription factors can either activate transcription (activators) or repress transcription (repressors). Regulatory elements were discovered in the 1960s and their general characteristics were worked out in the 1970s by studying specific transcription factors in bacteria and bacteriophage.
Promoters and regulatory sequences represent an abundant class of noncoding DNA but they mostly consist of a collection of relatively short sequences so they do not take up a very large fraction of the genome. The exact amount of regulatory DNA in mammalian genome is unclear because it is difficult to distinguish between spurious transcription factor binding sites and those that are functional. The binding characteristics of typical DNA-binding proteins were characterized in the 1970s and the biochemical properties of transcription factors predict that in cells with large genomes, the majority of binding sites will not be biologically functional.
Many regulatory sequences occur near promoters, usually upstream of the transcription start site of the gene. Some occur within a gene and a few are located downstream of the transcription termination site. In eukaryotes, there are some regulatory sequences that are located at a considerable distance from the promoter region. These distant regulatory sequences are often called enhancers but there is no rigorous definition of enhancer that distinguishes it from other transcription factor binding sites. | 1 | Gene expression + Signal Transduction |