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The high intensity of the Jameson Cell means that it is much shorter than conventional column flotation cells (see Figure 1), and it does not require air compressors to aerate the suspension of ground ore particles and water (known as a slurry or pulp) in the flotation cell. The lack of a requirement for compressed air and the lack of moving parts means that power consumption is less than for the equivalent mechanical or conventional column flotation cell.
In contrast to most types of flotation cell, the Cell introduces the feed and the air to the Cell in a combined stream via one or more cylindrical columns referred to as "downcomers". Other types of flotation cell typically introduce the feed and the air separately to the cell.
The Cell produces fast mineral flotation rates, especially for very fine mineral particles. It produces high concentrate grades from fast floating liberated particles and is able to do this from a single stage of flotation. The high carrying capacity of the Jameson Cell is particularly beneficial when high yields (mass pulls) are required, such as in recleaning in metals flotation and in the flotation of metallurgical coal, where yields can exceed 80%.
The Cell was initially developed as a lower-cost alternative to conventional column flotation cells for recovering fine particles, and was first used in the Mount Isa lead–zinc concentrator in 1988. Since then, use of the technology has spread to include coal flotation, base and precious metal flotation, potash flotation, oil sands flotation, molybdenum flotation, graphite flotation and cleaning solvent extraction liquors. Xstrata Technology, Glencore Xstratas technology marketing arm, listed 328 Jameson Cell installations in May 2013. Cells have been installed by 94 companies in 27 countries. Today, the technology is the standard in the Australian Coal Industry where well over one hundred Cells have been installed to recover coal fines. It is mainly used in metals applications to solve final grade and capacity issues from conventional cell cleaner circuits. It has found a niche in transforming traditional circuit designs where its inclusion allows cleaner circuits to be designed with fewer cells in a smaller footprint, while achieving cleaner and/or higher grade concentrates. It has also made possible the recovery of previously discarded fine materials, such as coal and phosphate fines, thereby increasing the efficiency and extending the life of the worlds non-renewable natural resources. | 0 | Metallurgy |
The variable region rearrangements happen in an orderly sequence in the bone marrow. Usually, the assortment of these gene segments occurs at B cell maturation. | 1 | Gene expression + Signal Transduction |
The echinoderm and flatworm mitochondrial code (translation table 9) is a genetic code used by the mitochondria of certain echinoderm and flatworm species. | 1 | Gene expression + Signal Transduction |
In pyrotechnics, it is used as fuel to make special mixtures, e.g. for production of smokes, in flash compositions, and in percussion caps. Specification for pyrotechnic calcium silicide is MIL-C-324C. In some mixtures it may be substituted with ferrosilicon. Silicon-based fuels are used in some time delay mixtures, e.g. for controlling of explosive bolts, hand grenades, and infrared decoys. Smoke compositions often contain hexachloroethane; during burning they produce silicon tetrachloride, which, like titanium tetrachloride used in smoke-screens, reacts with air moisture and produces dense white fog. Gum arabic is used in some mixtures to inhibit calcium silicide decomposition. | 0 | Metallurgy |
The Pattinson process was patented by its inventor, Hugh Lee Pattinson, in 1833 who described it as "An improved method for separating silver from lead". It exploited the fact that in molten lead containing traces of silver the first metal to solidify out of the melt is lead, leaving the remaining liquid richer in silver. Pattinson's equipment consisted basically of nothing more complex than a row of up to 13 iron pots, which were heated from below. Some lead, naturally containing a small percentage of silver, was loaded into the central pot and melted. This was then allowed to cool. As the lead solidified it is removed using large perforated iron ladles and moved to the next pot in one direction, and the remaining metal which was now richer in silver was then transferred to the next pot in the opposite direction. The process was repeated from one pot to the next, the lead accumulating in the pot at one end and metal enriched in silver in the pot at the other. The level of enrichment possible is limited by the lead-silver eutectic and typically the process stopped around 600 to 700 ounces per ton (approx 2%), so further separation is carried out by cupellation.
The process was economic for lead containing at least 250 grams of silver per ton. | 0 | Metallurgy |
Several reuptake inhibitors of VMATs are known to exist, including reserpine (RES), tetrabenazine (TBZ), dihydrotetrabenazine (DTBZOH), and ketanserin (KET). It is thought that RES exhibits competitive inhibition, binding to the same site as the monoamine substrate, as studies have shown that it can be displaced via introduction of norepinephrine. TBZ, DTBZOH, and KET are thought to exhibit non-competitive inhibition, instead binding to allosteric sites and decreasing the activity of the VMAT rather than simply blocking its substrate binding site. It has been found that these inhibitors are less effective at inhibiting VMAT1 than VMAT2, and the inhibitory effects of the tetrabenazines on VMAT1 is negligible. | 1 | Gene expression + Signal Transduction |
Hyperactive mTOR pathways have been identified in certain lymphoproliferative diseases such as autoimmune lymphoproliferative syndrome (ALPS), multicentric Castleman disease, and post-transplant lymphoproliferative disorder (PTLD). | 1 | Gene expression + Signal Transduction |
The Journal of Mining and Metallurgy, Section B: Metallurgy is a biannual peer-reviewed scientific journal that covers mining and metallurgy. The editor-in-chief is Dragana Živković (University of Belgrade). Publishing formats include original research articles, review articles, short notices, letters, and book reviews. | 0 | Metallurgy |
Heap leaching dates back to the second century BC in China, where iron was combined with copper sulfate. By the time of the Northern Song Dynasty, a copper alloy was able to be recovered by leaching.
Leaching can also be traced back to alchemy. Early examples of leaching performed by alchemists resembled mixing iron with copper sulfate, yielding a layer of metallic copper. In the 8th century, Jabir Ibn Hayyan, an Arab alchemist, discovered a substance he coined "aqua regia". Aqua regia, a combination of hydrochloric acid and nitric acid, was found to be effective in dissolving gold, which was previously thought to be insoluble. | 0 | Metallurgy |
The United States Department of Agriculture (USDA) web site has a very complete searchable table of calcium content (in milligrams) in foods, per common measures such as per 100 grams or per a normal serving. | 1 | Gene expression + Signal Transduction |
RNA Polymerase II exists in two forms unphosphorylated and phosphorylated, IIA and IIO respectively. The transition between the two forms facilitates different functions for transcription. The phosphorylation of CTD is catalyzed by one of the six general transcription factors, TFIIH. TFIIH serves two purposes: one is to unwind the DNA at the transcription start site and the other is to phosphorylate. The form polymerase IIA joins the preinitiation complex, this is suggested because IIA binds with higher affinity to the TBP (TATA-box binding protein), the subunit of the general transcription factor TFIID, than polymerase IIO form. The form polymerase IIO facilitates the elongation of the RNA chain. The method for the elongation initiation is done by the phosphorylation of Serine at position 5 (Ser5), via TFIIH. The newly phosphorylated Ser5 recruits enzymes to cap the 5 end of the newly synthesized RNA and the "3 processing factors to poly(A) sites". Once the second Serine is phosphorylated, Ser2, elongation is activated. In order to terminate elongation dephosphorylation must occur. Once the domain is completely dephosphorylated the RNAP II enzyme is "recycled" and catalyzes the same process with another initiation site. | 1 | Gene expression + Signal Transduction |
In 1993 Philex Mining Corporation, a Philippines mining company, replaced the mechanical cleaner circuit with Cells at its Benguet copper concentrator. Following their successful operation, Philex replaced the mechanical cells in its cleaner-scavenger circuit in 1994 and began the phased introduction of Cell rougher and scavenger lines that was completed in early 1996. This was the first operation in which the external recycle mechanism system was applied. By the time the last Jameson Cell was installed, the entire flotation circuit was composed of Jameson Cells.
The motivation for installing Jameson Cells was, in part, to take advantage of their space-saving capabilities and to improve copper recovery at a minimum cost. The Cell circuit occupied 60% less floor area and achieved equivalent results to the mechanical banks with 40% of their residence time. They provided a power saving of 18%.
In addition to these benefits, the use of the Jameson Cells in the rougher and rougher–scavenger section of the plant resulted in a 3.3% increase in copper recovery and a 4.5% increase in gold recovery. When combined with the other Cells in the cleaner, recleaner and cleaner–scavenger section, there was a 2.6% increase in final copper concentrate grade and a 3.5% increase in plant copper recovery, with a 2.6% increase in plant gold recovery. | 0 | Metallurgy |
Sintering is part of the firing process used in the manufacture of pottery and other ceramic objects. Sintering and vitrification (which requires higher temperatures) are the two main mechanisms behind the strength and stability of ceramics. Sintered ceramic objects are made from substances such as glass, alumina, zirconia, silica, magnesia, lime, beryllium oxide, and ferric oxide. Some ceramic raw materials have a lower affinity for water and a lower plasticity index than clay, requiring organic additives in the stages before sintering.
Sintering begins when sufficient temperatures have been reached to mobilize the active elements in the ceramic material, which can start below their melting point (typically at 50–80% of their melting point), e.g. as premelting. When sufficient sintering has taken place, the ceramic body will no longer break down in water; additional sintering can reduce the porosity of the ceramic, increase the bond area between ceramic particles, and increase the material strength.
Industrial procedures to create ceramic objects via sintering of powders generally include:
* mixing water, binder, deflocculant, and unfired ceramic powder to form a slurry
*spray-drying the slurry
* putting the spray dried powder into a mold and pressing it to form a green body (an unsintered ceramic item)
* heating the green body at low temperature to burn off the binder
* sintering at a high temperature to fuse the ceramic particles together.
All the characteristic temperatures associated with phase transformation, glass transitions, and melting points, occurring during a sinterisation cycle of a particular ceramic's formulation (i.e., tails and frits) can be easily obtained by observing the expansion-temperature curves during optical dilatometer thermal analysis. In fact, sinterisation is associated with a remarkable shrinkage of the material because glass phases flow once their transition temperature is reached, and start consolidating the powdery structure and considerably reducing the porosity of the material.
Sintering is performed at high temperature. Additionally, a second and/or third external force (such as pressure, electric current) could be used. A commonly used second external force is pressure. Sintering performed by only heating is generally termed "pressureless sintering", which is possible with graded metal-ceramic composites, utilising a nanoparticle sintering aid and bulk molding technology. A variant used for 3D shapes is called hot isostatic pressing.
To allow efficient stacking of product in the furnace during sintering and to prevent parts sticking together, many manufacturers separate ware using ceramic powder separator sheets. These sheets are available in various materials such as alumina, zirconia and magnesia. They are additionally categorized by fine, medium and coarse particle sizes. By matching the material and particle size to the ware being sintered, surface damage and contamination can be reduced while maximizing furnace loading. | 0 | Metallurgy |
The pack mill process begins with a tin bar, which is a drawn flat bar that was usually purchased from an ironworks or steel works. The tin bar could be wrought iron or mild steel. The cross-section of the bar needed to be accurate in size as this dictates the length and thickness of the final plates. The bar was cut to the correct length to make the desired size plate. For instance, if a plate is desired the tin bar is cut to a length and width that is divisible by 14 and 20. The bar is then rolled and doubled over, with the number of times being doubled over dependent on how large the tin bar is and what the final thickness is. If the starting tin bar is then it must be at least finished on the fours, or doubled over twice, and if a thin gauge is required then it may be finished on the eights, or doubled over three times. The tin bar is then heated to a dull red heat and passed five or six times through the roughing rolls. Between each pass the plate is passed over (or round) the rolls, and the gap between the rolls is narrowed by means of a screw. The plate is then reheated and run through the finishing rolls.
If the plate is not finished on singles, or without doubling the plate over, it is doubled over in a squeezer. The squeezer was like a table where one half of the surface folds over on top of the other and a press flattens the doubled over plate so the rolled end will fit in the rollers. It is then reheated for another set of rolling. This is repeated until the desired geometry is reached. Note that if the plate needs to be doubled over more than once the rolled end is sheared off. The pack is then allowed to cool. When cool, the pack is sheared slightly undersized from the final dimensions and the plates separated by openers.
At this point, the plates are covered in scale and must be pickled. This involves dipping the plates in sulfuric acid for five minutes. The pickling turns the scales into a greenish-black slime which is removed via annealing. The plates are annealed for approximately 10 hours and then allowed to slowly cool. At this point the plates are known as pickled and annealed black plates. These plates were commonly sold for stamping and enameling purposes.
After this, the plates are rough and not straight, so they are cold rolled several times. The rolling lengthens the plates to their final dimension. They are then annealed again to remove any strain hardening. These plates are called black plate pickled, cold rolled, and close annealed (black plate p. cr. and ca.). To attain perfect cleanliness the plates are pickled again in a weak sulfuric acid. Finally they are rinsed and stored in water until ready to be tinned.
The tinning set consists of at least one pot of molten tin, with a zinc chloride flux on top, and a grease pot. The flux dries the plate and prepares it for the tin to adhere. If a second tin pot is used, called the wash pot, it contains tin at a lower temperature. This is followed by the grease pot, which contains oil and a tinning machine. The tinning machine has two small rollers that are spring-loaded together so that when the tinned plate is inserted the rolls squeeze off any excess tin. The springs on the tinning machine can be set to different forces to give different thicknesses of tin. Finally, the oil is cleaned off with fine bran and dusted clean.
What is described here is the process as employed during the 20th century. The process grew somewhat in complexity over time, as it was found that the inclusion of additional procedures improved quality. The practice of hot rolling and then cold rolling evidently goes back to the early days, as the Knight family's tinplate works had (from its foundation in about 1740) two rolling mills, one at Bringewood (west of Ludlow) which made blackplate, and the other the tin mill at Mitton (now part of Stourport, evidently for the later stages. | 0 | Metallurgy |
Splicing of all intron-containing RNA molecules is superficially similar, as described above. However, different types of introns were identified through the examination of intron structure by DNA sequence analysis, together with genetic and biochemical analysis of RNA splicing reactions. At least four distinct classes of introns have been identified:
*Introns in nuclear protein-coding genes that are removed by spliceosomes (spliceosomal introns)
* Introns in nuclear and archaeal transfer RNA genes that are removed by proteins (tRNA introns)
* Self-splicing group I introns that are removed by RNA catalysis
* Self-splicing group II introns that are removed by RNA catalysis
Group III introns are proposed to be a fifth family, but little is known about the biochemical apparatus that mediates their splicing. They appear to be related to group II introns, and possibly to spliceosomal introns. | 1 | Gene expression + Signal Transduction |
By the early 1950s it was known from metabolic labeling studies using radioactive phosphate that phosphate groups attached to phosphoproteins inside cells can sometimes undergo rapid exchange of new phosphate for old. In order to perform experiments that would allow isolation and characterization of the enzymes involved in attaching and removing phosphate from proteins, there was a need for convenient substrates for protein kinases and protein phosphatases. Casein has been used as a substrate since the earliest days of research on protein phosphorylation. By the late 1960s, cyclic AMP-dependent protein kinase had been purified, and most attention was centered on kinases and phosphatases that could regulate the activity of important enzymes. Casein kinase activity associated with the endoplasmic reticulum of mammary glands was first characterized in 1974, and its activity was shown to not depend on cyclic AMP. | 1 | Gene expression + Signal Transduction |
Corrosion may occur where stale sewage generates hydrogen sulfide gas into an atmosphere containing oxygen gas and high relative humidity. There must be an underlying anaerobic aquatic habitat containing sulfates and an overlying aerobic aquatic habitat separated by a gas phase containing both oxygen and hydrogen sulfide at concentrations in excess of 2 ppm. | 0 | Metallurgy |
The basic term is often prefixed to define the actual purpose of the ladle. The basic ladle design can therefore include many variations that improve the usage of the ladle for specific tasks. For example:
* Casting ladle: a ladle used to pour molten metal into moulds to produce the casting.
* Transfer ladle: a ladle used to transfer a large amount of molten metal from one process to another. Typically a transfer ladle will be used to transfer molten metal from a primary melting furnace to either a holding furnace or an auto-pour unit.
* Treatment ladle: a ladle used for a process to take place within the ladle to change some aspect of the molten metal. A typical example being to convert cast iron to ductile iron by the addition of various elements into the ladle.
Unless the ladle is to be used with alloys that have very low temperature melting point, the ladle is also fitted with a refractory lining. It is the refractory lining that stops the steel vessel from suffering damage when the ladle is used to transport metals with high melting temperatures that, if the molten metal came in direct contact with the ladle shell, would rapidly melt through the shell. Refractory lining materials come in many forms and the right choice very much depends on each foundry's working practices. Traditionally ladles used to be lined using pre-cast firebricks however refractory concretes have tended to supersede these in many countries.
Foundry ladles are normally rated by their working capacity rather than by their physical size. Hand-held ladles are typically known as handshank ladles and are fitted with a long handle to keep the heat of the metal away from the person holding it. Their capacity is limited to what a man can safely handle. Larger ladles are usually referred to as geared crane ladles. Their capacity is usually determined by the ladle function. Small hand-held ladles might also be crucibles that are fitted with carrying devices. However, in most foundries, the foundry ladle refers to a steel vessel that has a lifting bail fitted so that the vessel can be carried by an overhead crane or monorail system and is also fitted with a mechanical means for rotating the vessel, usually in the form of a gearbox. The gearbox can either be manually operated or powered operation. (See the paragraph below for further details).
For the transportation of very large volumes of molten metal, such as in steel mills, the ladle can run on wheels, a purpose-built ladle transfer car or be slung from an overhead crane and will be tilted using a second overhead lifting device.
The most common shape for a ladle is a vertical cone, but other shapes are possible. Having a tapered cone as the shell adds strength and rigidity to the shell. Having the taper also helps when it comes time to remove the refractory lining. However straight sided shells are also fabricated as are other shapes.
The most common of these other shapes is known as a drum ladle and is shaped as a horizontal cylinder suspended between two bogies. Large versions, often having capacities in excess of are used in steel mills are often referred to as torpedo ladles. Torpedo ladles are commonly used to transport liquid iron from a blast furnace to another part of the steel mill. Some versions are even adapted so that they can be carried on special bogies that can be transported by either road or rail. | 0 | Metallurgy |
These luxurious products were most often sold in important jewellery stores. Sometimes the retailer's paper labels survived the cleaning attempts of the last decades, and these labels are always a keen addition for any collector. They confirm that silver overlay porcelain and glass was sold all over Germany.
Friedrich Deusch, the oldest and biggest firm, also sold internationally and even produced a large amount of silver overlay tableware for the Royal House of Saudi Arabia. Deusch is the only firm that has survived (as of 2013), although the focus of production has
changed from fine art to galvanizing parts for the automobile industry. In 1976, after three generations, the Deusch family relinquished interest in the firm of Friedrich Deusch and Company Today, there is scant knowledge and interest about this firm's history.
Veyhl (father and son) traveled a lot offering their newest items to different jewellery stores. Later, they opened their own shop in Plüderhausen (close to Schwäbisch Gmünd). Friedrich Wilhelm Spahr created timeless designs which can be found today all over Europe and even in the United States. These are rare, desirable and mostly exquisite.
Silver overlay was a very exclusive luxury ware from the beginning because of the very complicated and time-consuming steps of manufacturing. Silver overlay items were never mass-produced and were made in limited numbers. The development of silver overlay was forged by a technical alliance between artists, artisans and advances in chemistry, physics, electronics and, ultimately, the industrialized techniques of the late 19th century. The arts movements of the day were philosophically against industrialized techniques. Yet, ironically, many delightfully decorated pieces of silver overlay porcelain and glass can be seen with superb handicraft and Art Nouveau-inspired designs. Thus, while the handicraft movement died after a single incandescent generation, their designs live on, as do the stunning works of Friedrich Deusch, Friedrich Wilhelm Spahr, and Alfred & Manfred Vehyl. | 0 | Metallurgy |
From 2001 to 2007, nickel prices rose from an average of US$5945 to US$37,216. Nickel is a key constituent of 316L stainless steel. This, combined with increases in some of the other constituents of the 316L alloy, prompted Xstrata Technology (by then the marketing organisation for the Isa Process technology) to seek an alternative material for the cathode plates.
Xstrata Technology personnel investigated the use of a new low-alloyed duplex stainless steel, LDX 2101 and 304L stainless steel. The LDX 2101 contains 1.5% nickel compared to 10–14% in 316L stainless steel.
LDX 2101 has superior mechanical strength to the 316L stainless steel, allowing thinner sheets to be used for the cathode plates. However, the flatness tolerance of commercially available LDX 2101 steel did not meet the required specifications. Xstrata Technology worked with a manufacturer to produce sheets that did meet the required flatness tolerance.
Xstrata Technology also had to develop a finish that allowed the surface to function in the same way as 316L.
Cathode plates using LDX 2010 have equivalent corrosion resistance to 316L plates.
The LDX 2101 alloy provides an alternative to the 316L stainless steel, with the selection depending on relatively prices of the various steels. | 0 | Metallurgy |
Within set concrete there remains some free "calcium hydroxide" (Ca(OH)), which can further dissociate to form Ca and hydroxide (OH) ions". Any water which finds a seepage path through micro cracks and air voids present in concrete, will readily carry the (Ca(OH)) and Ca (depending on solution pH and chemical reaction at the time) to the underside of the structure where leachate solution contacts the atmosphere. Carbon dioxide (CO) from the atmosphere readily diffuses into the leachate and causes a chemical reaction, which precipitates (deposits) calcium carbonate (CaCO) on the outside of the concrete structure. Consisting primarily of CaCO this secondary deposit derived from concrete is known as "calthemite" and can mimic the shapes and forms of cave "speleothems", such as stalactites, stalagmites, flowstone etc. Other trace elements such as iron from rusting reinforcing steel bars may be transported and deposited by the leachate at the same time as the CaCO. This may colour the calthemites orange or red.
The chemistry involving the leaching of calcium hydroxide from concrete can facilitate the growth of calthemites up to ≈200 times faster than cave speleothems due to the different chemical reactions involved. The sight of calthemite is a visual sign that calcium is being leached from the concrete structure and the concrete is gradually degrading.
In very old concrete where the calcium hydroxide has been leached from the leachate seepage path, the chemistry may revert to that similar to "speleothem" chemistry in limestone cave. This is where carbon dioxide enriched rain or seepage water forms a weak carbonic acid, which leaches calcium carbonate (CaCO) from within the concrete structure and carries it to the underside of the structure. When it contacts the atmosphere, carbon dioxide degasses and calcium carbonate is precipitated to create calthemite deposits, which mimic the shapes and forms of speleothems. This degassing chemistry is not common in concrete structures as the leachate can often find new paths through the concrete to access free calcium hydroxide and this reverts the chemistry to that previously mentioned where CO is the reactant. | 0 | Metallurgy |
GCN2 (encoded in humans by the gene EIF2AK4) is activated as a result of amino acid deprivation. The mechanisms regarding this activation are still being researched; however, one mechanism has been studied in yeast. It was observed that GCN2 binds to uncharged/deacylated tRNA which causes a conformational change, resulting in dimerization. Dimerization then causes autophosphorylation and activation. Other stressors have also been reported to activate GCN2. GCN2 activation was observed in glucose deprived tumor cells, although it was suggested that it was an indirect effect due to cells using amino acids as an alternate energy source. In mouse embryonic fibroblast cells and human keratinocytes, GCN2 was activated due to UV light exposure. The pathways for this activation require further research, although multiple models have been proposed, including crosslinking between GCN2 and tRNA. | 1 | Gene expression + Signal Transduction |
There was a quarterly report on each research topic presented to the individual research committee and an annual one circulated also to members on request. Final results were compiled as a report that was immediately available to members. After about two years the commercial confidentiality was dropped and a paper was presented at a meeting of the Institute of Metals or other organisation and subsequently published in their Journal. Some researches that had resulted in valuable definitive advancements were then published in book form. | 0 | Metallurgy |
In a normal bearing the surfaces are separated by a layer of oil, this is known as elastohydrodynamic (EHD) lubrication. If the thickness of the EHD film is of the same order of magnitude as the surface roughness, the surface topography is able to interact and cause micro pitting. A thin EHD film may be caused by excess load or temperature, a lower oil viscosity than is required, low speed or water in the oil. Water in the oil can make micro pitting worse by causing hydrogen embrittlement of the surface. Micro pitting occurs only under poor EHD lubrication conditions.
A surface with a deep scratch might break exactly at the scratch if stress is applied. One can imagine that the surface roughness is a composite of many very small scratches. So high surface roughness decreases the stability on heavy stressed parts. To get a good overview of the surface an areal scan (Surface metrology) gives more information that a measurement along a single profile (profileometer). To quantify the surface roughness the ISO 25178 can be used. | 0 | Metallurgy |
Copper-clad steel (CCS), also known as copper-covered steel or the trademarked name Copperweld is a bi-metallic product, mainly used in the wire industry that combines the high mechanical strength of steel with the conductivity and corrosion resistance of copper.
It is mainly used for grounding purposes, line tracing to locate underground utilities, drop wire of telephone cables, and inner conductor of coaxial cables, including thin hookup cables like RG-174 and CATV cable. It is also used in some antennas for RF conducting wires. | 0 | Metallurgy |
CpG DNA methylation has showed a role to regulate the alternative splicing in social insects. In honey bees (Apis mellifera), CpG DNA methylation seems to regulate the exon skipping based on the first few genomic studies after honey bee genome was available. CpG DNA methylation regulated alternative splicing more extensively, not only affect exon skipping, but also intron retention, and other splicing events. | 1 | Gene expression + Signal Transduction |
Junk DNA is DNA that has no biologically relevant function such as pseudogenes and fragments of once active transposons. Bacteria and viral genomes have very little junk DNA but some eukaryotic genomes may have a substantial amount of junk DNA. The exact amount of nonfunctional DNA in humans and other species with large genomes has not been determined and there is considerable controversy in the scientific literature.
The nonfunctional DNA in bacterial genomes is mostly located in the intergenic fraction of non-coding DNA but in eukaryotic genomes it may also be found within introns. It is important to note that there are many examples of functional DNA elements in non-coding DNA and that it is erroneous to equate non-coding DNA with junk DNA. | 1 | Gene expression + Signal Transduction |
An unnatural base pair (UBP) is a designed subunit (or nucleobase) of DNA that is created in a laboratory and does not occur in nature. In 2012, a group of American scientists led by Floyd Romesberg, a chemical biologist at the Scripps Research Institute in San Diego, California, published that his team had designed two unnatural base pairs
named d5SICS and dNaM. More technically, these artificial nucleotides bearing hydrophobic nucleobases feature two fused aromatic rings that form a d5SICS–dNaM complex or base pair in DNA. In 2014, the same team reported that they had synthesized a plasmid containing natural T-A and C-G base pairs along with the best-performing UBP Romesbergs laboratory had designed and inserted it into cells of the common bacterium E. coli, which successfully replicated the unnatural base pairs through multiple generations. This is the first known example of a living organism passing along an expanded genetic code to subsequent generations. This was in part achieved by the addition of a supportive algal gene that expresses a nucleotide triphosphate transporter which efficiently imports the triphosphates of both d5SICSTP and dNaMTP into E. coli' bacteria. Then, the natural bacterial replication pathways use them to accurately replicate the plasmid containing d5SICS–dNaM.
The successful incorporation of a third base pair is a significant breakthrough toward the goal of greatly expanding the number of amino acids which can be encoded by DNA, from the existing 20 amino acids to a theoretically possible 172, thereby expanding the potential for living organisms to produce novel proteins. Earlier, the artificial strings of DNA did not encode for anything, but scientists speculated they could be designed to manufacture new proteins which could have industrial or pharmaceutical uses. Transcription of DNA containing unnatural base pairs and translation of corresponding mRNA were actually achieved recently. In November 2017, the same team at the Scripps Research Institute that first introduced two extra nucleobases into bacterial DNA reported having constructed a semi-synthetic E. coli bacteria able to make proteins using such DNA. Its DNA contained six different nucleobases: four canonical and two artificially added, dNaM and dTPT3 (these two form a pair). The bacteria had two corresponding RNA bases included in two new codons, additional tRNAs recognizing these new codons (these tRNAs also contained two new RNA bases within their anticodons) and additional amino acids, enabling the bacteria to synthesize "unnatural" proteins.
Another demonstration of UBPs were achieved by Ichiro Hiraos group at RIKEN institute in Japan. In 2002, they developed an unnatural base pair between 2-amino-8-(2-thienyl)purine (s) and pyridine-2-one (y) that functions in vitro in transcription and translation, for the site-specific incorporation of non-standard amino acids into proteins. In 2006, they created 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds) and pyrrole-2-carbaldehyde (Pa) as a third base pair for replication and transcription. Afterward, Ds and 4-[3-(6-aminohexanamido)-1-propynyl]-2-nitropyrrole (Px) was discovered as a high fidelity pair in PCR amplification. In 2013, they applied the Ds-Px pair to DNA aptamer generation by in vitro' selection (SELEX) and demonstrated the genetic alphabet expansion significantly augment DNA aptamer affinities to target proteins. | 1 | Gene expression + Signal Transduction |
Copper is almost non-existent for most of the interior of East Africa, with a few exceptions particularly Kilwa and medieval sites in Nubia and Fostat, and there is not enough information yet to reconstruct copper on the Swahili Coast. | 0 | Metallurgy |
In natural gas cyclic processes, a unit produces hot reducing gas, which is injected into the reactor. To ensure continuous operation of the unit converting natural gas into reducing gas, several tanks are operated in parallel and with a time lag.
The best-known of this type is HYL I and its improved variant, HYL II. This is the oldest industrial direct gas reduction process, developed in Mexico in 1957 by the Hylsa company. | 0 | Metallurgy |
The advent of sequencing has permitted scientists to elucidate a huge landscape of new miRNAs, to increase our knowledge of the biogenesis involved and to discover putative post-transcriptional editing processes in miRNAs ignored until now. These processes mostly generate variations of the current miRNAs that are annotated in miRBase in the 3 and 5 terminus and in minor frequencies, nucleotide substitution along the miRNA length,. The variations are mainly generated by a shift of Drosha and Dicer in the cleavage site, but also by nucleotide additions at the 3-end, resulting in new sequences different from the annotated miRNA. These were named "isomiRs" by Morin et al., 2008. IsomiRs have been well established along different species in metazoa and deeply described for the first time in human stem cells and human brain samples. Moreover, it has been proven that isomiRs are not caused by RNA degradation during sample preparation for next generation sequencing. Some studies have tried to explain the miRNA diversity by structural bases of precursors but without clear results. The functionality of adenylation or uridynilation at the 3end (3addition isomiRs) has been related to alterations in the miRNA-3-UTR stability. Furthermore, differential expression of isomiRs has been detected during development in D. melanogaster and Hippoglossus hippoglossus L., suggesting a biological function.
*Trimming variants: these are possible due to slight variations by Drosha and/or Dicer
*Nucleotide addition: Wyman et al. have described the process of nucleotide transferases adding individual nucleotides to miRNA sequences
*Nucleotide substitution: there is a huge range of possible changes in such an event, some of them can be explained by current Adenosine_deaminase like A to G or C to U, in a similar way to what happens in post-transcriptional RNA editing events involving mRNA. | 1 | Gene expression + Signal Transduction |
During the 1970s the BNF became the BNF Metals Technology Centre and moved out of London to Grove Laboratories, Denchworth Road, Wantage, Oxfordshire. Recognising globalisation, membership was then opened to companies based overseas. In 1990 the BNF bought Fulmer Research Laboratories from the Institute of Physics and was renamed the BNF-Fulmer, then BNF (Fulmer Materials Centre). The laboratories were closed in 1992. | 0 | Metallurgy |
There are two methods of smelting zinc: the pyrometallurgical process and the electrolysis process. Both methods are still used. Both of these processes share the same first step: roasting. | 0 | Metallurgy |
Depending on the field of literature being surveyed, one might encounter the same compound referred to with different chemical formulas. An example of the most common difference is XYZ versus XYZ, where the labels of the two transition metals X and Y in the compound are swapped. The traditional convention XYZ arises from the interpretation of Heuslers as intermetallics and is used predominantly in literature studying magnetic applications of Heuslers compounds. The XYZ convention on the other hand is used mostly in thermoelectric materials and transparent conducting applications literature where semiconducting Heuslers (most half-Heuslers are semiconductors) are used. This convention, in which the left-most element on the periodic table comes first, uses the Zintl interpretation of semiconducting compounds where the chemical formula XYZ is written in order of increasing electronegativity. In well-known compounds such as FeVAl which were historically thought of as metallic (semi-metallic) but were more recently shown to be small-gap semiconductors one might find both styles being used. In the present article semiconducting compounds might sometimes be mentioned in the XYZ style. | 0 | Metallurgy |
*H. Schubert, History of British Iron and Steel Industry c.450 BC to AD 1775 (1957), 272–291.
*A. den Ouden, "The Production of Wrought Iron in Finery Hearths", Historical Metallurgy 15(2) (1981), 63–87 and 16(1) (1982), 29–33.
*K-G. Hildebrand, Swedish Iron in the Seventeenth and Eighteenth Centuries: Export Industry Before Industrialization (Stockholm 1992).
*P. King, The Cartel in Oregrounds Iron: Trading in the Raw Material for Steel During the 18th century", Journal of Industrial History' 6 (2003), 25–48. | 0 | Metallurgy |
Retinaldehyde is a retinol (vitamin A) derivative responsible for vision. It binds rhodopsin, a well-characterized GPCR that binds all-cis retinal in its inactive state. Upon photoisomerization by a photon the cis-retinal is converted to trans-retinal causing activation of rhodopsin which ultimately leads to depolarization of the neuron thereby enabling visual perception. | 1 | Gene expression + Signal Transduction |
Dynamic recrystallization is the process of removing the internal strain that remains in grains during deformation. This happens by the reorganization of a material with a change in grain size, shape, and orientation within the same mineral. When recrystallization occurs after deformation has come to an end and particularly at high temperatures, the process is called static recrystallization or annealing. Dynamic recrystallization results in grain size-reduction and static recrystallization results in the formation of larger equant grains.
Dynamic recrystallization can occur under a wide range of metamorphic conditions, and can strongly influence the mechanical properties of the deforming material. Dynamic recrystallization is the result of two end-member processes: (1) The formation and rotation of subgrains (rotation recrystallization) and (2) grain-boundary migration (migration recrystallization).
# Rotation recrystallization (subgrain rotation) is the progressive misorientation of a subgrain as more dislocations move into the dislocation wall (a zone of dislocations resulting from climb, cross-slip, and glide), which increases the crystallographic mismatch across the boundary. Eventually, the misorientation across the boundary is sufficiently large enough to recognize individual grains (usually 10–15° misorientation). Grains tend to be elongate or ribbon-shape, with many subgrains, with a characteristic gradual transition from low-angle subgrains to high-angle boundaries.
# Migration recrystallization (grain-boundary migration) is the processes by which a grain grows at the expense of the neighboring grains. At low temperatures, the mobility of the grain boundary may be local, and the grain boundary may bulge into a neighboring grain with a high dislocation density and form new, smaller, independent crystals by a process called low-temperature grain boundary migration, or bulging recrystallization. The bulges produced can separate from the original grain to form new grains by the formation of subgrain (low-angle) boundaries, which can evolve into grain boundaries, or by migration of the grain boundary. Bulging recrystallization often occurs along boundaries of old grains at triple junctions. At high temperatures, the growing grain has a lower dislocation density than the grain(s) consumed, and the grain boundary sweeps through the neighboring grains to remove dislocations by high-temperature grain-boundary migration crystallization. Grain boundaries are lobate with a variable grain size, with new grains generally larger than existing subgrains. At very high temperatures, grains are highly lobate or ameboid, but can be nearly strain-free. | 0 | Metallurgy |
CKLF like MARVEL transmembrane domain-containing 7 (i.e. CMTM7), previously termed chemokine-like factor superfamily 7 (i.e. CKLFSF7), is a protein that in humans is encoded by the CMTM7 gene. This gene, which is located in band 22 on the short (i.e. "p") arm of chromosome 3, and the protein that it encodes belong to the CKLF-like MARVEL transmembrane domain-containing family. Through the process of alternative splicing, the CMTM7 gene encodes two isoforms, CMTM7-v1 and CMTM7-v2, with CMTM7-v1 being the main form expressed and studied. CMTM7 proteins are widely expressed in normal human tissues. | 1 | Gene expression + Signal Transduction |
* Computational analysis tools such as t-test, hierarchical clustering, self-organizing maps, regulatory network reconstruction, BLAST searches, pattern-motif discovery, protein structure prediction, structure-based protein annotation, etc.
* Visualization of gene expression (heatmaps, volcano plot), molecular interaction networks (through Cytoscape), protein sequence and protein structure data (e.g., MarkUs).
* Integration of gene and pathway annotation information from curated sources as well as through Gene Ontology enrichment analysis.
* Component integration through platform management of inputs and outputs. Among data that can be shared between components are expression datasets, interaction networks, sample and marker (gene) sets and sequences.
* Dataset history tracking - complete record of data sets used and input settings.
* Integration with 3rd party tools such as Genepattern, Cytoscape, and Genomespace.
Demonstrations of each feature described can be found at[http://wiki.c2b2.columbia.edu/workbench/index.php/Tutorials GeWorkbench-web Tutorials]. | 1 | Gene expression + Signal Transduction |
RNA splicing is a process in molecular biology where a newly-made precursor messenger RNA (pre-mRNA) transcript is transformed into a mature messenger RNA (mRNA). It works by removing all the introns (non-coding regions of RNA) and splicing back together exons (coding regions). For nuclear-encoded genes, splicing occurs in the nucleus either during or immediately after transcription. For those eukaryotic genes that contain introns, splicing is usually needed to create an mRNA molecule that can be translated into protein. For many eukaryotic introns, splicing occurs in a series of reactions which are catalyzed by the spliceosome, a complex of small nuclear ribonucleoproteins (snRNPs). There exist self-splicing introns, that is, ribozymes that can catalyze their own excision from their parent RNA molecule. The process of transcription, splicing and translation is called gene expression, the central dogma of molecular biology. | 1 | Gene expression + Signal Transduction |
The valley or wadi of Nahal Mishmar begins in the Hebron hills, running east towards the Dead Sea. Its western part is shallow, at an altitude of approximately 270 m above sea level, and it proceeds to fall more than 300 meters into the Jordan Rift Valley before emptying into the Dead Sea, over . Nahal Mishmar runs north of the Tze'elim Stream, between Ein Gedi and Masada.
Access is from Highway 90. | 0 | Metallurgy |
Titanium and titanium alloys have been wide usage in aerospace, medical, and maritime applications. The most known titanium alloy that adopts solid solution strengthening is Ti-6Al-4V. Also, the addition of oxygen to pure Ti alloy adopts a solid solution strengthening as a mechanism to the material, while adding it to Ti-6Al-4V alloy doesn’t have the same influence. | 0 | Metallurgy |
Degeneracy of the genetic code was identified by Lagerkvist. For instance, codons GAA and GAG both specify glutamic acid and exhibit redundancy; but, neither specifies any other amino acid and thus are not ambiguous or demonstrate no ambiguity.
The codons encoding one amino acid may differ in any of their three positions; however, more often than not, this difference is in the second or third position. For instance, the amino acid glutamic acid is specified by GAA and GAG codons (difference in the third position); the amino acid leucine is specified by UUA, UUG, CUU, CUC, CUA, CUG codons (difference in the first or third position); and the amino acid serine is specified by UCA, UCG, UCC, UCU, AGU, AGC (difference in the first, second, or third position).
Degeneracy results because there are more codons than encodable amino acids. For example, if there were two bases per codon, then only 16 amino acids could be coded for (4²=16). Because at least 21 codes are required (20 amino acids plus stop) and the next largest number of bases is three, then 4³ gives 64 possible codons, meaning that some degeneracy must exist. | 1 | Gene expression + Signal Transduction |
Cold spraying (or gas dynamic cold spraying) was introduced to the market in the 1990s. The method was originally developed in the Soviet Union – while experimenting with the erosion of the target, which was exposed to a two-phase high-velocity flow of fine powder in a wind tunnel, scientists observed accidental rapid formation of coatings.
In cold spraying, particles are accelerated to very high speeds by the carrier gas forced through a converging–diverging de Laval type nozzle. Upon impact, solid particles with sufficient kinetic energy deform plastically and bond mechanically to the substrate to form a coating. The critical velocity needed to form bonding depends on the material's properties, powder size and temperature. Metals, polymers, ceramics, composite materials and nanocrystalline powders can be deposited using cold spraying.
Soft metals such as Cu and Al are best suited for cold spraying, but coating of other materials (W, Ta, Ti, MCrAlY, WC–Co, etc.) by cold spraying has been reported.
The deposition efficiency is typically low for alloy powders, and the window of process parameters and suitable powder sizes is narrow. To accelerate powders to higher velocity, finer powders (<20 micrometers) are used. It is possible to accelerate powder particles to much higher velocity using a processing gas having high speed of sound (helium instead of nitrogen).
However, helium is costly and its flow rate, and thus consumption, is higher. To improve acceleration capability, nitrogen gas is heated up to about 900 °C. As a result, deposition efficiency and tensile strength of deposits increase. | 0 | Metallurgy |
An early ironmaster was John Winter (about 1600–1676) who owned substantial holdings in the Forest of Dean. During the English Civil War he cast cannons for Charles I. Following the Restoration, Winter developed his interest in the iron industry, and experimented with a new type of coking oven. This was a precursor to the later work of Abraham Darby I who successfully used coke to smelt iron. | 0 | Metallurgy |
Molten chloride salt mixtures are commonly used as quenching baths for various alloy heat treatments, such as annealing and martempering of steel. Cyanide and chloride salt mixtures are used for surface modification of alloys such as carburizing and nitrocarburizing of steel.
Cryolite (a fluoride salt) is used as a solvent for aluminium oxide in the production of aluminium in the Hall-Héroult process.
Fluoride, chloride, and hydroxide salts can be used as solvents in pyroprocessing of nuclear fuel. | 0 | Metallurgy |
* Advantages
** Some advantages to Biological and bio-hybrid drug carriers include but are not limited to offering compatibility with the human immune system, having the potential to be genetically modified, and having the capacity to hold drugs. Moreover, an essential advantage is their natural property of homing to inflammation and tumor sites. This natural property of homing to inflammation and tumor sites can enhance the targeted delivery of drugs, minimizing the risk of off-target effects and reducing the required dosage. Additionally, these systems have the potential to increase drug stability and prolong circulation time in the body, improving drug efficacy and reducing the frequency of dosing. Overall, these advantages make biological and bio-hybrid drug carriers promising for developing more effective and targeted drug delivery systems.
* Limitations
** One limitation of Biological and bio-hybrid drug carriers, especially leukocytes, is that they have a low drug-carrying capacity. A limit in the carrying capacity of a carrier means that researchers will have to use more medication to achieve the desired therapeutic effect, increasing the risk of adverse side effects and the cost of the treatment. Moreover, the short lifespan can limit their potential use for long-term drug delivery applications [35]. Coupling this aspect with an inability to penetrate deep into tumors and the potential for genetic mutations can pose significant challenges for future drug delivery systems. Therefore, despite their advantages, further research and development are needed to address current limitations and improve their clinical feasibility. | 1 | Gene expression + Signal Transduction |
Simple permutation-based estimation is used to determine how likely a given RP value or better is observed in a random experiment.
# generate p permutations of k rank lists of length n.
# calculate the rank products of the n genes in the p permutations.
# count how many times the rank products of the genes in the permutations are smaller or equal to the observed rank product. Set c to this value.
# calculate the average expected value for the rank product by: .
# calculate the percentage of false positives as : where is the rank of gene g in a list of all n genes sorted by increasing . | 1 | Gene expression + Signal Transduction |
Transfer RNA introns that depend upon proteins for removal occur at a specific location within the anticodon loop of unspliced tRNA precursors, and are removed by a tRNA splicing endonuclease. The exons are then linked together by a second protein, the tRNA splicing ligase. Note that self-splicing introns are also sometimes found within tRNA genes. | 1 | Gene expression + Signal Transduction |
Subcritical crack propagation in glasses falls into three regions. In region I, the velocity of crack propagation increases with ambient humidity due to stress-enhanced chemical reaction between the glass and water. In region II, crack propagation velocity is diffusion controlled and dependent on the rate at which chemical reactants can be transported to the tip of the crack. In region III, crack propagation is independent of its environment, having reached a critical stress intensity. Chemicals other than water, like ammonia, can induce subcritical crack propagation in silica glass, but they must have an electron donor site and a proton donor site. | 0 | Metallurgy |
While the loss of a tumor suppressor such as pRb leading to uncontrolled cell proliferation is detrimental in the context of cancer, it may be beneficial to deplete or inhibit suppressive functions of pRb in the context of cellular regeneration. Harvesting the proliferative abilities of cells induced to a controlled “cancer like” state could aid in repairing damaged tissues and delay aging phenotypes. This idea remains to be thoroughly explored as a potential cellular injury and anti-aging treatment. | 1 | Gene expression + Signal Transduction |
In genetics, attenuation is a regulatory mechanism for some bacterial operons that results in premature termination of transcription. The canonical example of attenuation used in many introductory genetics textbooks, is ribosome-mediated attenuation of the trp operon. Ribosome-mediated attenuation of the trp operon relies on the fact that, in bacteria, transcription and translation proceed simultaneously. Attenuation involves a provisional stop signal (attenuator), located in the DNA segment that corresponds to the leader sequence of mRNA. During attenuation, the ribosome becomes stalled (delayed) in the attenuator region in the mRNA leader. Depending on the metabolic conditions, the attenuator either stops transcription at that point or allows read-through to the structural gene part of the mRNA and synthesis of the appropriate protein.
Attenuation is a regulatory feature found throughout Archaea and Bacteria causing premature termination of transcription. Attenuators are 5-cis' acting regulatory regions which fold into one of two alternative RNA structures which determine the success of transcription. The folding is modulated by a sensing mechanism producing either a Rho-independent terminator, resulting in interrupted transcription and a non-functional RNA product; or an anti-terminator structure, resulting in a functional RNA transcript. There are now many equivalent examples where the translation, not transcription, is terminated by sequestering the Shine-Dalgarno sequence (ribosomal binding site) in a hairpin-loop structure. While not meeting the previous definition of (transcriptional) attenuation, these are now considered to be variants of the same phenomena and are included in this article. Attenuation is an ancient regulatory system, prevalent in many bacterial species providing fast and sensitive regulation of gene operons and is commonly used to repress genes in the presence of their own product (or a downstream metabolite). | 1 | Gene expression + Signal Transduction |
Selective laser melting (also known as powder bed fusion) is an additive manufacturing procedure used to create intricately detailed forms from a CAD file. A shape is designed and then converted into slices. These slices are sent to a laser writer to print the final product. In brief, a bed of metal powder is prepared, and a slice is formed in the powder bed by a high energy laser sintering the particles together. The powder bed moves downwards, and a new batch of metal powder is rolled over the top. This layer is then sintered with the laser, and the process is repeated until all slices have been processed. Additive manufacturing can leave pores behind. Many products undergo a heat treatment or hot isostatic pressing procedure to densify the product and reduce porosity. | 0 | Metallurgy |
The structures of both eukaryotic and prokaryotic genes involve several nested sequence elements. Each element has a specific function in the multi-step process of gene expression. The sequences and lengths of these elements vary, but the same general functions are present in most genes. Although DNA is a double-stranded molecule, typically only one of the strands encodes information that the RNA polymerase reads to produce protein-coding mRNA or non-coding RNA. This sense or coding strand, runs in the 5 to 3 direction where the numbers refer to the carbon atoms of the backbone's ribose sugar. The open reading frame (ORF) of a gene is therefore usually represented as an arrow indicating the direction in which the sense strand is read.
Regulatory sequences are located at the extremities of genes. These sequence regions can either be next to the transcribed region (the promoter) or separated by many kilobases (enhancers and silencers). The promoter is located at the 5' end of the gene and is composed of a core promoter sequence and a proximal promoter sequence. The core promoter marks the start site for transcription by binding RNA polymerase and other proteins necessary for copying DNA to RNA. The proximal promoter region binds transcription factors that modify the affinity of the core promoter for RNA polymerase. Genes may be regulated by multiple enhancer and silencer sequences that further modify the activity of promoters by binding activator or repressor proteins. Enhancers and silencers may be distantly located from the gene, many thousands of base pairs away. The binding of different transcription factors, therefore, regulates the rate of transcription initiation at different times and in different cells.
Regulatory elements can overlap one another, with a section of DNA able to interact with many competing activators and repressors as well as RNA polymerase. For example, some repressor proteins can bind to the core promoter to prevent polymerase binding. For genes with multiple regulatory sequences, the rate of transcription is the product of all of the elements combined. Binding of activators and repressors to multiple regulatory sequences has a cooperative effect on transcription initiation.
Although all organisms use both transcriptional activators and repressors, eukaryotic genes are said to be default off, whereas prokaryotic genes are default on. The core promoter of eukaryotic genes typically requires additional activation by promoter elements for expression to occur. The core promoter of prokaryotic genes, conversely, is sufficient for strong expression and is regulated by repressors.
An additional layer of regulation occurs for protein coding genes after the mRNA has been processed to prepare it for translation to protein. Only the region between the start and stop codons encodes the final protein product. The flanking untranslated regions (UTRs) contain further regulatory sequences. The 3' UTR contains a terminator sequence, which marks the endpoint for transcription and releases the RNA polymerase. The 5’ UTR binds the ribosome, which translates the protein-coding region into a string of amino acids that fold to form the final protein product. In the case of genes for non-coding RNAs, the RNA is not translated but instead folds to be directly functional. | 1 | Gene expression + Signal Transduction |
In 1910 British polar explorer Robert Scott hoped to be the first to reach the South Pole, but was beaten by Norwegian explorer Roald Amundsen. On foot, the expedition trudged through the frozen deserts of the Antarctic, marching for caches of food and kerosene deposited on the way. In early 1912, at the first cache, there was no kerosene; the cans – soldered with tin – were empty. The cause of the empty tins could have been related to tin pest. The tin cans were recovered and no tin pest was found when analyzed by the Tin Research Institute. Some observers blame poor quality soldering, as tin cans over 80 years old have been discovered in Antarctic buildings with the soldering in good condition. | 0 | Metallurgy |
Typical stages in a U6 snRNA (also termed class III) gene initiation (documented in vertebrates only):
*SNAPc (SNRNA Activating Protein complex; subunits: 1, 2, 3, 4, 5) (also termed PBP and PTF) binds to the PSE (Proximal Sequence Element) centered approximately 55 base pairs upstream of the start site of transcription. This assembly is greatly stimulated by the Pol II transcription factors Oct1 and STAF that bind to an enhancer-like DSE (Distal Sequence Element) at least 200 base pairs upstream of the start site of transcription. These factors and promoter elements are shared between Pol II and Pol III transcription of snRNA genes.
*SNAPc acts to assemble TFIIIB at a TATA box centered 26 base pairs upstream of the start site of transcription. It is the presence of a TATA box that specifies that the snRNA gene is transcribed by Pol III rather than Pol II.
*The TFIIIB for U6 snRNA transcription contains a smaller Brf1 paralogue, Brf2.
*TFIIIB is the transcription factor that assembles Pol III at the start site of transcription. Sequence conservation predicts that TFIIIB containing Brf2 also plays a role in promoter opening. | 1 | Gene expression + Signal Transduction |
Desensitization of the postsynaptic receptors is a decrease in response to the same neurotransmitter stimulus. It means that the strength of a synapse may in effect diminish as a train of action potentials arrive in rapid succession – a phenomenon that gives rise to the so-called frequency dependence of synapses. The nervous system exploits this property for computational purposes, and can tune its synapses through such means as phosphorylation of the proteins involved. | 1 | Gene expression + Signal Transduction |
The metals of antiquity generally have low melting points, with iron being the exception.
* Mercury melts at −38.829 °C (−37.89 °F) (being liquid at room temperature).
* Tin melts at 231 °C (449 °F)
* Lead melts at 327 °C (621 °F)
* Silver at 961 °C (1763 °F)
* Gold at 1064 °C (1947 °F)
* Copper at 1084 °C (1984 °F)
* Iron is the outlier at 1538 °C (2800 °F), making it far more difficult to melt in antiquity. Cultures developed ironworking proficiency at different rates; however, evidence from the Near East suggests that smelting was possible but impractical circa 1500 BC, and relatively commonplace across most of Eurasia by 500 BC. However, until this period, generally known as the Iron Age, ironwork would have been impossible.
The other metals discovered before the Scientific Revolution largely fit the pattern, except for high-melting platinum:
* Bismuth melts at 272 °C (521 °F)
* Zinc melts at 420 °C (787 °F), but importantly boils at 907 °C (1665 °F), a temperature below the melting point of silver. Consequently, at the temperatures needed to reduce zinc oxide to the metal, the metal is already gaseous.
* Arsenic sublimes at 615 °C (1137 °F), passing directly from the solid state to the gaseous state.
* Antimony melts at 631 °C (1167 °F)
* Platinum melts at 1768 °C (3215 °F), even higher than iron. Native South Americans worked with it instead by sintering: they combined gold and platinum powders, until the alloy became soft enough to shape with tools. | 0 | Metallurgy |
*AkzoNobel Coil Coatings Europe, https://web.archive.org/web/20130528041259/http://www.akzonobel.com/CCE/coil_coatings/ourindustry/ecca/,
*ArcelorMittal, http://www.constructalia.com/francais/actualites/plus_dactus/plus_dactus100/magazine_ecca_2012_une_source_d_inspiration_pour_les_architectes,
*Shingels, https://web.archive.org/web/20140714204231/http://shingels.com/?page_id=657&lang=en,
*Precoat Metals, http://www.precoat.com/links.htm,
*Spooner Industries, http://www.spooner.co.uk/products/36/coil-coating ,
*Novacel, http://www.novacel.fr/fr/novacel/partenariat.html ,
*The Plan "Architecture and Technologies in details", https://web.archive.org/web/20140714212808/http://www.theplan.it/J/index.php?option=com_content&view=article&id=2366:alcoa&Itemid=1&lang=en,
*Union of International Associations, http://www.uia.be/s/or/en/1100007909,
*Tata Steel, http://www.tatasteel.com/,
*BASF, http://www.basf.com/ | 0 | Metallurgy |
A finery forge was used to refine wrought iron at least by the 3rd century BC in ancient China, based on the earliest archaeological specimens of cast and pig iron fined into wrought iron and steel found at the early Han Dynasty (202 BC – 220 AD) site at Tieshengguo. Pigott speculates that the finery forge existed in the previous Warring States period (403–221 BC), because of the wrought iron items from China dating to that period and there was no documented evidence of the bloomery ever being used in China. Wagner writes that in addition to the Han Dynasty hearths believed to be fining hearths, there is also pictorial evidence of the fining hearth from a Shandong tomb mural dated 1st to 2nd century AD, as well as a hint of written evidence in the 4th century AD Daoist text Taiping Jing.
In Europe, the concept of the finery forge may have been evident as early as the 13th century. However, it was perhaps not capable of being used to fashion plate armor until the 15th century, as described in conjunction with the waterwheel-powered blast furnace by the Florentine Italian engineer Antonio Averlino (c. 1400 - 1469). The finery forge process began to be replaced in Europe from the late 18th century by others, of which puddling was the most successful, though some continued in use through the mid-19th century. The new methods used mineral fuel (coal or coke), and freed the iron industry from its dependence on wood to make charcoal. | 0 | Metallurgy |
The yeast mediator complex is approximately as massive as a small subunit of a eukaryotic ribosome. The yeast mediator is composed of 25 subunits, while the mammalian mediator complexes are slightly larger. Mediator can be divided into 4 main parts: The head, middle, tail, and the transiently associated CDK8 kinase module.
Mediator subunits have many intrinsically disordered regions called "splines", which may be important to allow the structural changes of the mediator that change the function of the complex. The figure shows how the splines of the Med 14 subunit connect a large portion of the complex together while still allowing flexibility.
Mediator complexes that lack a subunit have been found or produced. These smaller mediators can still function normally in some activity, but lack other capabilities. This indicates a somewhat independent function of some of the subunits while being part of the larger complex.
Another example of structural variability is seen in vertebrates, in which 3 paralogues of subunits of the cyclin-dependent kinase module have evolved by 3 independent gene duplication events followed by sequence divergence. There is a report that mediator forms stable associations with a particular type of non-coding RNA, ncRNA-a. These stable associations have also been shown to regulate gene expression in vivo, and are prevented by mutations in MED12 that produce the human disease FG syndrome. Thus, the structure of a mediator complex can be augmented by RNA as well as proteinaceous transcription factors. | 1 | Gene expression + Signal Transduction |
Fluxes have several important properties:
* Activity – the ability to dissolve existing oxides on the metal surface and promote wetting with solder. Highly active fluxes are often acidic or corrosive in nature.
* Corrosivity – the promotion of corrosion by the flux and its residues. Most active fluxes tend to be corrosive at room temperatures and require careful removal. As activity and corrosivity are linked, the preparation of surfaces to be joined should allow use of milder fluxes. Some water-soluble flux residues are hygroscopic, which causes problems with electrical resistance and contributes to corrosion. Fluxes containing halides and mineral acids are highly corrosive and require thorough removal. Some fluxes, especially those based on borax used for brazing, form very hard glass-like coatings that are difficult to remove.
* Cleanability – the difficulty of removal of flux and its residues after the soldering operation. Fluxes with higher content of solids tend to leave larger amount of residues; thermal decomposition of some vehicles also leads to formation of difficult-to-clean, polymerized and possibly even charred deposits (a problem especially for hand soldering). Some flux residues are soluble in organic solvents, others in water, some in both. Some fluxes are no-clean, as they are sufficiently volatile or undergo thermal decomposition to volatile products, that they do not require the cleaning step. Other fluxes leave non-corrosive residues that can be left in place. However, flux residues can interfere with subsequent operations; they can impair adhesion of conformal coatings, or act as undesired insulation on connectors and contact pads for test equipment.
* Residue tack – the stickiness of the surface of the flux residue. When not removed, the flux residue should have smooth, hard surface. Tacky surfaces tend to accumulate dust and particulates, which causes issues with electrical resistance; the particles themselves can be conductive or they can be hygroscopic or corrosive.
* Volatility – this property has to be balanced to facilitate easy removal of solvents during the preheating phase but to not require too frequent replenishing of solvent in the process equipment.
* Viscosity – especially important for solder pastes, which have to be easy to apply but also thick enough to stay in place without spreading to undesired locations. Solder pastes may also function as a temporary adhesive for keeping electronic parts in place before and during soldering. Fluxes applied by e.g. foam require low viscosity.
* Flammability – relevant especially for glycol-based vehicles and for organic solvents. Flux vapors tend to have low autoignition temperature and present a risk of a flash fire when the flux comes in contact with a hot surface.
* Solids – the percentage of solid material in the flux. Fluxes with low solids, sometimes as little as 1–2%, are called low solids flux, low-residue flux, or no clean flux. They are often composed of weak organic acids, with addition of small amount of rosin or other resins.
* Conductivity – some fluxes remain conductive after soldering if not cleaned properly, leading to random malfunctions on circuits with high impedances. Different types of fluxes are differently prone to cause these issues. | 0 | Metallurgy |
CK2 is a protein kinase responsible for phosphorylation of substrates in various pathways within a cell; ATP or GTP can be used as phosphate source. CK2 has a dual functionality with involvement in cell growth/proliferation and suppression of apoptosis. CK2s anti-apoptotic function is in the continuation of the cell cycle; from G1 to S phase and G2 to M phase checkpoints. This function is achieved by protecting proteins from caspase-mediated apoptosis via phosphorylation of sites adjacent to the caspase cleavage site, blocking the activity of caspase proteins. CK2 also protects from drug-induced apoptosis via similar methods but it is not as well understood. Knockdown studies of both α and α’ sub-units have been used to verify this anti-apoptotic function.
Important phosphorylation events also regulated by CK2 are found in DNA damage repair pathways, and multiple stress-signaling pathways. Examples are phosphorylation of p53 or MAPK, which both regulate many interactions within their respective cellular pathways.
Another indication of separate function of α subunits is that mice that lack CK2α’ have a defect in the morphology of developing sperm. | 1 | Gene expression + Signal Transduction |
In addition to the NUTM1 fusion genes in the above cited carcinomas, recent studies have found NUTM1 fusion genes in malignancies with undifferentiated spindle cell, round cell, and epithelioid cell-like features which are regarded as sarcomas. Sarcomas with NUTM1 fusion genes typically a) occur in some sites were sarcomas otherwise rarely develop and b) consist of tumor cells that express a NUTM1 gene fused to one of the MADS-box gene family genes (i.e. a MXD4, MGA, or MXD1 gne), or, alternatively, a BRD4, ZNF532, or CIC gene. A recent review listed the follow NUTM1 fusion gene-associated sarcomas:
* Colorectal sarcomas: Six cases, all with a MXD4-NUTM1 fusion gene.
* Lung sarcomas: Four cases, one each with a BRD4-NUTM1, MDX4-NUTM1, CIC-NUTM1, or MGA-NUTM1 fusion gene.
* Kidney sarcomas: Three cases, two with a BRD4-NUTM1 and one with a CIC-NUTM1 fusion gene.
* Sarcomas of the extremities: Two cases of foot sarcomas, one with a MGA-NUTM1 and one with a X-NUTM1 (i.e. X indicates the fusion partner is not identified) fusion gene; two cases of thigh sarcomas, one with a BRD4-NUTM1 and the other with a MGA-NUTM1 fusion gene; and one case of an arm sarcoma with a BCORL1-NUTM1 fusion gene (BCORL1 is the BCL6 corepressor like 1 gene).
* Bone sarcomas: One case of mandible sarcoma with a ZNF532-NUTM1 fusion gene and one case each of temporal bone and occipital bone sarcomas (both of which were also in nearby brain tissues) with a CIC-NUTM1 fusion gene.
* Other sites: One case each of: stomach sarcoma with a MXD1-NUTM1 fusion gene; brain parietal cortex sarcoma with a BRD4-NUTM1 fusion gene; brain dura sarcoma with a MGA-NUTM1 fusion gene; sarcoma of the scalp with a CIC-NUTM1 fusion gene; paravertebral sarcoma with a CIC-NUTM1 gene; pleural sarcoma with the MGA-NUTM1 fusion gene; epidural sarcoma with CIC-NUTM1 gene; brain lateral ventricle sarcoma with the CIC-NUTM1 fusion gene; brain parietal cortex sarcoma with a BRD4-NUTM1 fusion gene; and ovary with a MXD4-NUTM1 fusion gene.
In general, these NUTM1 fusion gene-associated sarcomas have very poor prognoses and require further study to determine of role of these fusion genes in the development and progression of their corresponding sarcomas. | 1 | Gene expression + Signal Transduction |
The rotary kilns maximum temperature ranges between 1,230 and 1,260 °C, which significantly exceeds the 1,000 to 1,050 °C threshold for iron oxide reduction. The main objective is to achieve a paste-like consistency of the ore gangue. The reduced iron agglomerates into 3 to 8 mm metal nodules called . If the infusibility of the gangue is high, the temperature must be increased, up to 1,400 °C for a basic charge. It is crucial to control the gangues hot viscosity. Among rotary drum direct reduction processes, it stands out for using high temperatures.
Another distinctive attribute of the procedure involves introducing powdered coal to the furnace outlet. Furthermore, the process has evolved to enable terminating the supply of coal and running exclusively on the coal dust or coke dust introduced with the ore. In this situation, solely combustion air is injected at the furnace outlet. Thermal efficiency is improved in shaft furnaces such as blast furnaces compared to rotary furnaces due to the air absorbing some of the Luppen heat. However, the oxygen in the air partially re-oxidizes the product, meaning that the Luppen is still altered by contact with air at the end or after leaving the furnace, despite complete reduction of iron in the furnace.
The hot assembly is discharged from the furnace and then rapidly cooled and crushed. The iron is separated from the slag via magnetic separation. Magnetically intermediate fines make up 5–15% of the charge. While partial melting of the charge leads to the increased density of the prereducts, it also requires significant energy consumption. | 0 | Metallurgy |
The optical microscope, scanning electron microscope, X-ray diffraction and petrographic analysis can be used to determine the types and distribution of minerals in slag. The minerals present in the slag are good indicators of the gas atmosphere in the furnace, the cooling rate of the slag and the homogeneity of the slag. The type of ore and flux used in the smelting process can be determined if there are elements of un-decomposed charge or even metal pills trapped in the slag.
Slag minerals are classified as silicates, oxides and sulfides. Bachmann classified the main silicates in slag according to the ratio between metal oxides and silica.
:::::Ratio MeO : SiO silicate examples
:::::::2 : 1 fayalite
:::::::2 : 1 monticellite
:::::::1.5 : 1 melilite
:::::::1 : 1 pyroxene
Fayalite (FeSiO) is the most common mineral found in ancient slag. By studying the shape of the fayalite, the cooling rates of the slag can be roughly estimated.
Fayalite reacts with oxygen to form magnetite:
:3FeSiO + O= 2FeO·FeO + 3SiO
Therefore, the gas atmosphere in the furnace can be calculated from the ratio of magnetite to fayalite in the slag.
The presence of metal sulfides suggests that a sulfidic ore has been used. Metal sulfides survive the oxidizing stage before smelting and therefore may also indicate a multi-stage smelting process.
When fayalite is replete with CaO, monticellite and pyroxene form. They are an indicator of a high calcium content in the ore. | 0 | Metallurgy |
The trematode mitochondrial code (translation table 21) is a genetic code found in the mitochondria of Trematoda. | 1 | Gene expression + Signal Transduction |
Nines are an informal logarithmic notation for proportions very near to one or, equivalently, percentages very near 100%. Put simply, "nines" are the number of consecutive nines in a percentage such as 99% (two nines) or a decimal fraction such as 0.999 (three nines). Their common uses include grading the purity of materials. | 0 | Metallurgy |
The table, like most shaking tables, consists of a riffled deck with a gentle tilt on a stable support to counteract the tables oscillation. A motor, usually mounted to the side, drives a small arm that shakes the table along its length. The riffles are typically less than high and cover more than half the tables surface. Varied riffle designs are available for specific applications. The riffles run longitudinally, parallel to the long dimension of the table. The table's shaking motion is parallel to the riffle pattern.
Deck construction varies from wood to hard-wearing fiberglass where the riffles are formed as part of the mold. The decks are lined with high coefficient-of-friction materials (linoleum, rubber or plastic), which assists in the mineral recovery process.
During operation, a slurry of < sample material consisting of about 25% solids by weight is fed with wash water along the top of the table, perpendicular to the direction of table motion. The table is shaken longitudinally, using a slow forward stroke and a rapid return strike that causes particles to migrate or crawl along the deck parallel to the direction of motion. Particles move diagonally across the deck from the feed end and separate on the table according to size and density. Water flow rate, table tilt angle and intensity of the shaking motion must be properly adjusted for effective mineral recovery.
The riffles cause mineral particles to stratify in the protected inter-riffle regions. The finest and heaviest particles are forced to the bottom and the coarsest and lightest particles remain at the top. Particle layers migrate across the riffles with addition of new slurry feed and continued water wash. The riffles are tapered and flatten (disappear) towards the concentrate end of the table. The taper of the riffles causes migrating particles of progressively finer size and higher density to be brought into contact with the flowing film of water that tops the riffles; lighter material is washed away as tailings and middlings. Final concentration takes place in the unriffled region at the end of the deck where the layer of material at this stage is usually only a few particles deep. | 0 | Metallurgy |
Recently, it has been proposed that autapses could possibly form as a result of neuronal signal transmission blockage, such as in cases of axonal injury induced by poisoning or impeding ion channels. Dendrites from the soma in addition to an auxiliary axon may develop to form an autapse to help remediate the neuron's signal transmission. | 1 | Gene expression + Signal Transduction |
The Copper Age, also called the Eneolithic or the Chalcolithic Age, has been traditionally understood as a transitional period between the Neolithic and the Bronze Age, in which a gradual introduction of the metal (native copper) took place, while stone was still the main resource utilized. Recent archaeology has found that the metal was not introduced so gradually and that this entailed significant social changes, such as developments in the type of habitation (larger villages, launching of fortifications), long-distance trade, and copper metallurgy.
Some of the earliest Copper Age artifacts were found in the 5th and 6th millennia BCE archaeological sites of the Vinča culture such as Majdanpek, Jarmovac and Pločnik (including a copper axe from 5500 BCE). Somewhat later, in the 5th millennium BCE, metalwork is attested at Rudna Glava mine in Serbia, and at Ai Bunar mine in Bulgaria.
3rd millennium BCE copper metalwork is attested in places like Palmela (Portugal), Cortes (Navarre), and Stonehenge (England). However, as often happens with the prehistoric times, the limits of the age cannot be clearly defined and vary between different sources. | 0 | Metallurgy |
There has been evidence that the nonsense-mediated mRNA decay pathway participates in X chromosome dosage compensation in mammals. In higher eukaryotes with dimorphic sex chromosomes, such as humans and fruit flies, males have one X chromosome, whereas females have two. These organisms have evolved a mechanism that compensates not only for the different number of sex chromosomes between the two sexes, but also for the differing X/autosome ratios. In this genome-wide survey, the scientists found that autosomal genes are more likely to undergo nonsense-mediated decay than X-linked genes. This is because NMD fine tunes X chromosomes and it was demonstrated by inhibiting the pathway. The results were that balanced gene expression between X and autosomes gene expression was decreased by 10–15% no matter the method of inhibition. The NMD pathway is skewed towards depressing expression of larger population or autosomal genes than x-linked ones. In conclusion, the data supports the view that the coupling of alternative splicing and NMD is a pervasive means of gene expression regulation. | 1 | Gene expression + Signal Transduction |
Corrosion monitoring is the use of a corrator (corrosion meter) or set of methods and equipment to provide offline or online information about corrosion rate expressed in mpy (mill per year). - for better care and to take or improve preventive measures to combat and protect against corrosion. In this article, the difference between corrosion monitoring and corrosion protection, its difference with corrosion inspection and also the relationship between them, as well as online corrosion monitoring methods, equipment used and applications of each of them, are presented. | 0 | Metallurgy |
Splicing is regulated by trans-acting proteins (repressors and activators) and corresponding cis-acting regulatory sites (silencers and enhancers) on the pre-mRNA. However, as part of the complexity of alternative splicing, it is noted that the effects of a splicing factor are frequently position-dependent. That is, a splicing factor that serves as a splicing activator when bound to an intronic enhancer element may serve as a repressor when bound to its splicing element in the context of an exon, and vice versa. The secondary structure of the pre-mRNA transcript also plays a role in regulating splicing, such as by bringing together splicing elements or by masking a sequence that would otherwise serve as a binding element for a splicing factor. Together, these elements form a "splicing code" that governs how splicing will occur under different cellular conditions.
There are two major types of cis-acting RNA sequence elements present in pre-mRNAs and they have corresponding trans-acting RNA-binding proteins. Splicing silencers are sites to which splicing repressor proteins bind, reducing the probability that a nearby site will be used as a splice junction. These can be located in the intron itself (intronic splicing silencers, ISS) or in a neighboring exon (exonic splicing silencers, ESS). They vary in sequence, as well as in the types of proteins that bind to them. The majority of splicing repressors are heterogeneous nuclear ribonucleoproteins (hnRNPs) such as hnRNPA1 and polypyrimidine tract binding protein (PTB). Splicing enhancers are sites to which splicing activator proteins bind, increasing the probability that a nearby site will be used as a splice junction. These also may occur in the intron (intronic splicing enhancers, ISE) or exon (exonic splicing enhancers, ESE). Most of the activator proteins that bind to ISEs and ESEs are members of the SR protein family. Such proteins contain RNA recognition motifs and arginine and serine-rich (RS) domains.
In general, the determinants of splicing work in an inter-dependent manner that depends on context, so that the rules governing how splicing is regulated form a splicing code. The presence of a particular cis-acting RNA sequence element may increase the probability that a nearby site will be spliced in some cases, but decrease the probability in other cases, depending on context. The context within which regulatory elements act includes cis-acting context that is established by the presence of other RNA sequence features, and trans-acting context that is established by cellular conditions. For example, some cis-acting RNA sequence elements influence splicing only if multiple elements are present in the same region so as to establish context. As another example, a cis-acting element can have opposite effects on splicing, depending on which proteins are expressed in the cell (e.g., neuronal versus non-neuronal PTB). The adaptive significance of splicing silencers and enhancers is attested by studies showing that there is strong selection in human genes against mutations that produce new silencers or disrupt existing enhancers. | 1 | Gene expression + Signal Transduction |
Bioresorbable (or bioabsorbable) metallic glass is a type of amorphous metal, which is based on the Mg-Zn-Ca ternary system. Containing only elements which already exist inside the human body, namely Mg, Zn and Ca, these amorphous alloys are a special type of biodegradable metal. | 0 | Metallurgy |
The Institution of Metallurgists was a British professional association for metallurgists, largely involved in the iron and steel industry. | 0 | Metallurgy |
Aberrant promoter hypermethylation of SFRP1 occurs frequently during the pathogenesis of human cancers and has been found to be one of the primary mechanisms in SFRP1 down-regulation. Methylation-specific PCR (MSP) is able to detect this epigenetic change and could be used for cancer detection. Detection and quantification of promoter CpG methylation in body fluid is both feasible and noninvasive. Combined MSP analyses of multiple genes in voided urine could provide a reliable way to improve cancer diagnosis.
Urakami et al. were able to detect cancers cells using conventional MSP analysis of Wnt-antagonist genes (including SFRP1) in voided urine of patients with bladder tumor. Their results showed a high percentage of identical methylation with tumor-tissue DNA. Conversely, no aberrant methylation was detected in >90% of urine DNA from normal controls. This demonstrates that methylation detection of SFRP1 is both feasible and reliable and that the urine methylation score (M score) of Wnt antagonist genes could be used as an excellent noninvasive diagnostic biomarker for bladder tumor. Furthermore, the M score of Wnt-antagonist genes may reflect the presence of bladder tumor that progresses to invasive disease that would signal for future aggressive treatment. An optimal hypermethylation panel of Wnt-antagonist genes could contribute significantly to early detection of bladder tumor and predict bladder tumor aggressiveness. In fact, the methylation of SFRP1 genes in fecal DNA isolated from stool samples has been used to screen for colorectal cancer. | 1 | Gene expression + Signal Transduction |
The cytoplasmic domains of the EpoR contain a number of phosphotyrosines that are phosphorylated by Jak2 and serve as docking sites for a variety of intracellular pathway activators and Stats (such as Stat5). In addition to activating Ras/AKT and ERK/MAP kinase, phosphatidylinositol 3-kinase/AKT pathway and STAT transcription factors, phosphotyrosines also serve as docking sites for phosphatases that negatively affect EpoR signaling in order to prevent overactivation that may lead to such disorders as erythrocytosis. In general, the defects in the erythropoietin receptor may produce erythroleukemia and familial erythrocytosis. Mutations in Jak2 kinases associated with EpoR can also lead to polycythemia vera. | 1 | Gene expression + Signal Transduction |
It carried out work on reactors for the British civil and military (submarine fleet) nuclear energy programmes, investigating metallurgy. In the first ten years, it carried out research on materials for fast breeder reactors; it was the first time that niobium had been part of a fast breeder reactor. The site investigated fracture mechanics, nuclear reactor physics and hydraulics.
Work on irradiation of metals was also carried out with the School of Materials, University of Manchester and the Department of Materials Science and Metallurgy, University of Cambridge. | 0 | Metallurgy |
Wet storage stain can be prevented for a limited amount of time by coating in a light oil, chromate conversion coatings, or phosphate conversion coatings. A more permanent solution is to paint the surface. | 0 | Metallurgy |
Smeltmills were water-powered mills used to smelt lead or other metals.
The older method of smelting lead on wind-blown bole hills began to be superseded by artificially-blown smelters. The first such furnace was built by Burchard Kranich at Makeney, Derbyshire in 1554, but produced less good lead than the older bole hill. William Humfrey (the Queen's assay master), and a leading shareholder in the Company of Mineral and Battery Works introduced the ore hearth from the Mendips about 1577. This was initially blown by a foot-blast, but was soon developed into a water-powered smelt mill at Beauchief (now a suburb of Sheffield).
A typical smelt mill had an orehearth and a slaghearth, the latter being used to reprocess slags from the orehearth in order to recover further lead from the slag | 0 | Metallurgy |
The grain size, shape and distribution of the foundry sand, the type and quantity of bonding materials, the density to which the sand is rammed, and the percentage of moisture used for tempering the sand are important factors in regulating the degree of permeability. | 0 | Metallurgy |
Sealing is the final step in the anodizing process. Acidic anodizing solutions produce pores in the anodized coating. These pores can absorb dyes and retain lubricants but are also an avenue for corrosion. When lubrication properties are not critical, they are usually sealed after dyeing to increase corrosion resistance and dye retention. There are three most common types of sealing.
# Long immersion in boiling-hot——deionized water or steam is the simplest sealing process, although it is not completely effective and reduces abrasion resistance by 20%. The oxide is converted into its hydrated form and the resulting swelling reduces the porosity of the surface.
# Mid-temperature sealing process which works at in solutions containing organic additives and metal salts. However, this process will likely leach the colors.
# Cold sealing process, where the pores are closed by impregnation of a sealant in a room-temperature bath, is more popular due to energy savings. Coatings sealed in this method are not suitable for adhesive bonding. Teflon, nickel acetate, cobalt acetate, and hot sodium or potassium dichromate seals are commonly used. MIL-A-8625 requires sealing for thin coatings (Types I and II) and allows it as an option for thick ones (Type III). | 0 | Metallurgy |
Within molecular and cell biology, temporal feedback, also referred to as interlinked or interlocked feedback, is a biological regulatory motif in which fast and slow positive feedback loops are interlinked to create "all or none" switches. This interlinking produces separate, adjustable activation and de-activation times. This type of feedback is thought to be important in cellular processes in which an "all or none" decision is a necessary response to a specific input. The mitotic trigger, polarization in budding yeast, mammalian calcium signal transduction, EGF receptor signaling, platelet activation, and Xenopus oocyte maturation are examples for interlinked fast and slow multiple positive feedback systems.
In biological systems, temporal feedback is a ubiquitous signal transduction motif that allows systems to convert graded inputs into decisive, all-or-none digital outputs. A system with interlinked fast and slow feedback loops produces a dual-time switch, which is rapidly inducible and robust to noise during stimulus. In contrast, a single fast or slow loop is separately responsible for the speed of switching and the stability of switches. Computer simulation studies have shown that linking two loops of the same kind brings no overall advantage over having a single loop, however the dual-loop switch performs in a monostable regime. Both single and dual loops can behave as a bistable switch. Several computational models have been produced to demonstrate the responses of single and dual positive feedback loop switches to stimuli. | 1 | Gene expression + Signal Transduction |
# Mixture of fuel and oxygen is injected into the combustion chamber.
# Powder feedstock is introduced into the chamber.
# Nitrogen gas is added between the fuel-oxygen mixture and powder feedstock in order to prevent backfiring.
# Mixture is ignited, and heated powder is ejected from the barrel onto the target material.
# Barrel is then purged by nitrogen gas ready for firing again.
# This process is repeated at a rate of between 1–10 Hz until desired thickness of coating is achieved. | 0 | Metallurgy |
Over the life of Fulmer about 500 people were members of staff. Among these, because of the wide range of projects that Fulmer undertook, investigators and other technical staff had to be able to adapt their specialist skills and to innovate. They were also expected to play a part in attracting the necessary funding from business or Government. | 0 | Metallurgy |
Cementation is a type of precipitation, a heterogeneous process in which ions are reduced to zero valence at a solid metallic interface. The process is often used to refine leach solutions.
Cementation of copper is a common example. Copper ions in solution, often from an ore leaching process, are precipitated out of solution in the presence of solid iron. The iron oxidizes, and the copper ions are reduced through the transfer of electrons. The reaction is spontaneous because copper is higher on the galvanic series than iron.
: Cu(aq) + Fe(s) → Cu(s) + Fe(aq)
This was a historically useful process for the production of copper, where the precipitated solid copper metal was recovered as flakes or powder on the surface of scrap iron.
Cementation is used industrially to recover a variety of heavy metals including cadmium, and the cementation of gold by zinc in the Merrill-Crowe process accounts for a substantial fraction of world gold production. | 0 | Metallurgy |
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The P promoter allows for tight regulation and control of a target gene in vivo. As explained above, P is regulated by the addition and absence of arabinose. As tested, the promoter can be further repressed with reduced levels of cAMP through the addition of glucose. Plasmid vectors have been constructed and tested with a selectable marker (Cm in this case), origin of replication, araC and operons, multiple cloning site and P promoter. Studies show that vectors are highly expressed and can be used, in combination with chromosomal null alleles, to study loss of function of essential genes. | 1 | Gene expression + Signal Transduction |
While the frequency of alterations of the RB gene is substantial for many human cancer types including as lung, esophageal, and liver, alterations in up-steam regulatory components of pRb such as CDK4 and CDK6 have been the main targets for potential therapeutics to treat cancers with dysregulation in the RB pathway. This focus has resulted in the recent development and FDA clinical approval of three small molecule CDK4/6 inhibitors (Palbociclib (IBRANCE, Pfizer Inc. 2015), Ribociclib (KISQUALI, Novartis. 2017), & Abemaciclib (VERZENIO, Eli Lilly. 2017)) for the treatment of specific breast cancer subtypes. However, recent clinical studies finding limited efficacy, high toxicity, and acquired resistance of these inhibitors suggests the need to further elucidate mechanisms that influence CDK4/6 activity as well as explore other potential targets downstream in the pRb pathway to reactivate pRb's tumor suppressive functions. Treatment of cancers by CDK4/6 inhibitors depends on the presence of pRb within the cell for therapeutic effect, limiting their usage only to cancers where RB is not mutated and pRb protein levels are not significantly depleted.
Direct pRb reactivation in humans has not been achieved. However, in murine models, novel genetic methods have allowed for in vivo pRb reactivation experiments. pRb loss induced in mice with oncogenic KRAS-driven tumors of lung adenocarcinoma negates the requirement of MAPK signal amplification for progression to carcinoma and promotes loss of lineage commitment as well as accelerate the acquisition of metastatic competency. Reactivation of pRb in these mice rescues the tumors towards a less metastatic state, but does not completely stop tumor growth due to a proposed rewiring of MAPK pathway signaling, which suppresses pRb through a CDK-dependent mechanism. | 1 | Gene expression + Signal Transduction |
The sensing of bacterial signals is performed by peptidoglycan recognition protein LC (PGRP-LC), a transmembrane protein with an intracellular domain. Binding of bacterial peptidoglycan leads to dimerization of PGRP-LC which generates the conformation needed to bind and activate the Imd protein. However alternate isoforms of PGRP-LC can also be expressed with different functions: PGRP-LCx recognizes polymeric peptidoglycan, while PGRP-LCa does not bind peptidoglycan directly but acts alongside PGRP-LCx to bind monomeric peptidoglycan fragments (called tracheal cytotoxin or "TCT"). Another PGRP (PGRP-LE) also acts intracellularly to bind TCT that has crossed the cell membrane or is derived from an intracellular infection. PGRP-LA promotes the activation of Imd signalling in epithelial cells, but the mechanism is still unknown.
Other PGRPs can inhibit the activation of Imd signalling by binding bacterial signals or inhibiting host signalling proteins: PGRP-LF is a transmembrane PGRP that lacks an intracellular domain and does not bind peptidoglycan. Instead PGRP-LF forms dimers with PGRP-LC preventing PGRP-LC dimerization and consequently activation of Imd signalling. A number of secreted PGRPs have amidase activity that downregulate the Imd pathway by digesting peptidoglycan into short, non-immunogenic fragments. These include PGRP-LB, PGRP-SC1A, PGRP-SC1B, and PGRP-SC2. Additionally, PGRP-LB is the major regulator in the gut. | 1 | Gene expression + Signal Transduction |
Being an endothermic reaction, heat is applied to initiate and sustain the reaction. This heat requirement may be very high. To keep reaction temperatures low, the processes are operated under pressure. The rotary kiln is typically used in dolomite calcination. In the rotary kiln, the raw material, calcinated dolomite, is mixed with the finely ground reducing agent, ferrosillicone and the catalyst, fluorite. The materials are mixed together and pressed into sphere shaped pellets and the mixed materials are charged into cylindrical nickel chromium steel retorts. A number of retorts are placed in a furnace in sealed paper bags to avoid moisture absorption so that calcined dolomite activity doesn't reduce magnesium yield. The pellets are then placed into a reduction tank and heated to 1200 °C. The inside of the furnace is vacuumed with a 13.3 Pa or higher, to produce magnesium vapour. Magnesium crystals are removed from the condensers, slag is removed as a solid and the retort is recharged. The crude magnesium is refined via flux, and commercial magnesium ingot is produced. | 0 | Metallurgy |
Englishman William Haynes patented a process in 1860 for separating sulfide and gangue minerals using oil. Later writers have pointed to Haynes's as the first "bulk oil flotation" patent, though there is no evidence of its being field tested, or used commercially. In 1877 the brothers Bessel (Adolph and August) of Dresden, Germany, introduced their commercially successful oil and froth flotation process for extracting graphite, considered by some the root of froth flotation. However, the Bessel process became uneconomical after the discovery of high-grade graphite in Sri Lanka and was largely forgotten.
Inventor Hezekiah Bradford of Philadelphia invented a "method of saving floating material in ore-separation” and received US patent No. 345951 on July 20, 1886. He would later go on to patent the Bradford Breaker, currently in use by the coal industry, in 1893. His "Bradford washer," patented 1870, was used to concentrate iron, copper and lead-zinc ores by specific gravity, but lost some of the metal as float off the concentration process. The 1886 patent was to capture this "float" using surface tension, the first of the skin-flotation process patents that were eclipsed by oil froth flotation.
On August 24, 1886, Carrie Everson received a patent for her process calling for oil[s] but also an acid or a salt, a significant step in the evolution of the process history. By 1890, tests of the Everson process had been made at Georgetown and Silver Cliff, Colorado, and Baker, Oregon. She abandoned the work upon the death of her husband, and before perfecting a commercially successful process. Later, during the height of legal disputes over the validity of various patents during the 1910s, Everson's was often pointed to as the initial flotation patent - which would have meant that the process was not patentable again by later contestants. Much confusion has been clarified recently by historian Dawn Bunyak. | 0 | Metallurgy |
RNA polymerase II is inhibited by α-Amanitin and other amatoxins. α-Amanitin is a highly poisonous substance found in many mushrooms. The mushroom poison has different effects on each of the RNA Polymerases: I, II, III. RNAP I is completely unresponsive to the substance and will function normally while RNAP III has a moderate sensitivity. RNAP II, however, is completely inhibited by the toxin. Alpha-Amanitin inhibits RNAP II by strong interactions in the enzyme's "funnel", "cleft", and the key "bridge α-helix" regions of the RPB-1 subunit. | 1 | Gene expression + Signal Transduction |
Exposure of concrete structures to neutrons and gamma radiation in nuclear power plants, and high-flux material testing reactors, can induce radiation damage to their concrete structural components. Paramagnetic defects and optical centers are easily formed, but very high fluxes are necessary to displace a sufficiently high number of atoms in the crystal lattice of the minerals present in concrete before significant mechanical damage is observed.
However, neutron irradiation with a very high neutron fluence (number of neutrons per unit of cross-section area: neutron/cm) is known to render amorphous a fraction of the quartz present in some concrete aggregates. This amorphization process is also called metamictization. Metamict quartz with its disordered lattice structure is prone to alkali–silica reaction and can thus be responsible of harmful chemical expansion in the concrete of nuclear containment structures. | 0 | Metallurgy |
Advantages:
* Can be machined, brazed, formed, cut with available processes.
* Develops a protective oxide layer that is self-healing.
* This oxide layer is stable and has a high emission coefficient.
* Allows the design of thin-walled structures (sandwich).
* Resistant to harsh weather conditions in the troposphere.
* Low maintenance cost.
* Low material cost.
Disadvantages:
* It has a higher expansion coefficient than other materials, causing higher thermal stresses.
* Higher density.
* Lower maximum allowable temperature. | 0 | Metallurgy |
If an inducer, a molecule that initiates the gene expression, is present, then it can interact with the repressor protein and detach it from the operator. RNA polymerase then can transcribe the message (expressing the gene). A co-repressor is a molecule that can bind to the repressor and make it bind to the operator tightly, which decreases transcription.
A repressor that binds with a co-repressor is termed an aporepressor or inactive repressor. One type of aporepressor is the trp repressor, an important metabolic protein in bacteria. The above mechanism of repression is a type of a feedback mechanism because it only allows transcription to occur if a certain condition is present: the presence of specific inducer(s). In contrast, an active repressor binds directly to an operator to repress gene expression.
While repressors are more commonly found in prokaryotes, they are rare in eukaryotes. Furthermore, most known eukaryotic repressors are found in simple organisms (e.g., yeast), and act by interacting directly with activators. This contrasts prokaryotic repressors which can also alter DNA or RNA structure.
Within the eukaryotic genome are regions of DNA known as silencers. These are DNA sequences that bind to repressors to partially or fully repress a gene. Silencers can be located several bases upstream or downstream from the actual promoter of the gene. Repressors can also have two binding sites: one for the silencer region and one for the promoter. This causes chromosome looping, allowing the promoter region and the silencer region to come in proximity of each other. | 1 | Gene expression + Signal Transduction |
The first mitogen-activated protein kinase to be discovered was ERK1 (MAPK3) in mammals. Since ERK1 and its close relative ERK2 (MAPK1) are both involved in growth factor signaling, the family was termed "mitogen-activated". With the discovery of other members, even from distant organisms (e.g. plants), it has become increasingly clear that the name is a misnomer, since most MAPKs are actually involved in the response to potentially harmful, abiotic stress stimuli (hyperosmosis, oxidative stress, DNA damage, low osmolarity, infection, etc.). Because plants cannot "flee" from stress, terrestrial plants have the highest number of MAPK genes per organism ever found. Thus the role of mammalian ERK1/2 kinases as regulators of cell proliferation is not a generic, but a highly specialized function. | 1 | Gene expression + Signal Transduction |
Numerous sAC splice variants are present in osteoclast and osteoblasts, and mutation in the human sAC gene is associated with low spinal density. Calcification by osteoblasts is intrinsically related with bicarbonate and calcium. Bone density experiments in mouse calvaria cultured indicates that HCO-sensing sAC is a physiological appropriate regulator of bone formation and/or reabsorption. | 1 | Gene expression + Signal Transduction |
The HNF3 subfamily members contain a winged helix DNA-binding domain and bind to DNA as monomers.
* HNF3α/FOXA1 (forkhead box A1)
* HNF3β/FOXA2 (forkhead box A2)
* HNF3γ/FOXA3 (forkhead box A3) | 1 | Gene expression + Signal Transduction |
Rust formation can be controlled with coatings, such as paint, lacquer, varnish, or wax tapes that isolate the iron from the environment. Large structures with enclosed box sections, such as ships and modern automobiles, often have a wax-based product (technically a "slushing oil") injected into these sections. Such treatments usually also contain rust inhibitors. Covering steel with concrete can provide some protection to steel because of the alkaline pH environment at the steel–concrete interface. However, rusting of steel in concrete can still be a problem, as expanding rust can fracture concrete from within.
As a closely related example, iron clamps were used to join marble blocks during a restoration attempt of the Parthenon in Athens, Greece, in 1898, but caused extensive damage to the marble by the rusting and swelling of unprotected iron. The ancient Greek builders had used a similar fastening system for the marble blocks during construction, however, they also poured molten lead over the iron joints for protection from seismic shocks as well as from corrosion. This method was successful for the 2500-year-old structure, but in less than a century the crude repairs were in imminent danger of collapse.
When only temporary protection is needed for storage or transport, a thin layer of oil, grease or a special mixture such as Cosmoline can be applied to an iron surface. Such treatments are extensively used when "mothballing" a steel ship, automobile, or other equipment for long-term storage.
Special anti-seize lubricant mixtures are available and are applied to metallic threads and other precision machined surfaces to protect them from rust. These compounds usually contain grease mixed with copper, zinc, or aluminium powder, and other proprietary ingredients. | 0 | Metallurgy |