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Uterine leiomyomas are the most common tumors found in the female genital tract. Leiomyomas have been reported to grow under the influence of ovarian steroids (estrogen and progesterone). Aberrations of wnt signaling, as well as SFRPs, can contribute to the neoplastic process. This led Fukuhara et al. to investigate whether SFRP1 is associated with the pathogenesis of uterine leiomyomas by analyzing mRNA and protein expression of SFRP1 in leiomyomas and matched normal myometrium. The following outlines their findings: | 1 | Gene expression + Signal Transduction |
Neurons in the olfactory system are unmyelinated and densely packed and thus the often small effects of ephaptic coupling are more easily seen. A number of studies have shown how inhibition among neurons in the olfactory system work to fine-tune integration of signals in response to odor. This inhibition has been shown to occur from changes in electrical potentials alone. The addition of ephaptic coupling to olfactory neuron models adds further support to the "dedicated-line" model in which each olfactory receptor sends its signal to one neuron. The inhibition due to ephaptic coupling would help account for the integration of signals that gives rise to more nuanced perception of smells. | 1 | Gene expression + Signal Transduction |
Most metal ores contain metals of interest (e.g. gold, copper, nickel) in some oxidized states and thus the goal of most metallurgical operations is to chemically reduce them to their pure metallic form. The question is how to convert highly impure metal ores into purified bulk metals. A vast array of operations have been developed to accomplish those tasks, one of which is electrowinning. In an ideal case, ore is extracted into a solution which is then subjected to electrolysis. The metal is deposited on the cathode. In a practical sense, this idealized process is complicated by some or all of the following considerations: the metal content is low (a few percent is typical), other metals deposit competitively with the desired one, the ore is not easily or efficiently dissolved. For these reasons, electrowinning is usually only used on purified solutions of a desired metal, e.g. cyanide-extracts of gold ores.
Because metal deposition rates are related to available surface area, maintaining properly working cathodes is important. Two cathode types exist, flat-plate and reticulated cathodes, each with its own advantages and disadvantages. Flat-plate cathodes can be cleaned and reused, and plated metals recovered by either mechanically scraping the cathode (or, the electrolyzed metal has a lower melting point than the cathode, heating the cathode to the electrolyzed metals melting point causing the electrolyzed metal to liquify and separate from the cathode, which remains solid). Reticulated cathodes have a much higher deposition rate compared to flat-plate cathodes due to their greater surface area. However, reticulated cathodes are not reusable and must' be sent off for recycling. Alternatively, starter cathodes of pre-refined metals can be used, which become an integral part of the finished metal ready for rolling or further processing. | 0 | Metallurgy |
The liberated catalytic subunits can then catalyze the transfer of ATP terminal phosphates to protein substrates at serine, or threonine residues. This phosphorylation usually results in a change in activity of the substrate. Since PKAs are present in a variety of cells and act on different substrates, PKA regulation and cAMP regulation are involved in many different pathways.
The mechanisms of further effects may be divided into direct protein phosphorylation and protein synthesis:
*In direct protein phosphorylation, PKA directly either increases or decreases the activity of a protein.
*In protein synthesis, PKA first directly activates CREB, which binds the cAMP response element (CRE), altering the transcription and therefore the synthesis of the protein. In general, this mechanism takes more time (hours to days). | 1 | Gene expression + Signal Transduction |
Electrode potential and other environmental factors such as temperature, pH and degree of aeration can greatly impact the results off this accelerated stress corrosion cracking test, as can the specimen surface finish and metallurgical condition. | 0 | Metallurgy |
A nanocrystalline (NC) material is a polycrystalline material with a crystallite size of only a few nanometers. These materials fill the gap between amorphous materials without any long range order and conventional coarse-grained materials. Definitions vary, but nanocrystalline material is commonly defined as a crystallite (grain) size below 100 nm. Grain sizes from 100 to 500 nm are typically considered "ultrafine" grains.
The grain size of a NC sample can be estimated using x-ray diffraction. In materials with very small grain sizes, the diffraction peaks will be broadened. This broadening can be related to a crystallite size using the Scherrer equation (applicable up to ~50 nm), a Williamson-Hall plot, or more sophisticated methods such as the Warren-Averbach method or computer modeling of the diffraction pattern. The crystallite size can be measured directly using transmission electron microscopy. | 0 | Metallurgy |
Materials with yield strength anomalies are used in nuclear reactors due to their high temperature mechanical properties and good corrosion resistance. | 0 | Metallurgy |
In the 1960s it was headquartered at 17 Belgrave Square in the City of Westminster. In the 1970s it moved to Northway House on the A1000 (High Road) in north London. | 0 | Metallurgy |
Given n genes and k replicates, let the rank of gene g in the i-th replicate.
Compute the rank product via the geometric mean: | 1 | Gene expression + Signal Transduction |
The Castner process is a process for manufacturing sodium metal by electrolysis of molten sodium hydroxide at approximately 330 °C. Below that temperature, the melt would solidify; above that temperature, the molten sodium would start to dissolve in the melt. | 0 | Metallurgy |
Ca ion flow regulates several secondary messenger systems in neural adaptation for visual, auditory, and the olfactory system. It may often be bound to calmodulin such as in the olfactory system to either enhance or repress cation channels. Other times the calcium level change can actually release guanylyl cyclase from inhibition, like in the photoreception system. Ca ion can also determine the speed of adaptation in a neural system depending on the receptors and proteins that have varied affinity for detecting levels of calcium to open or close channels at high concentration and low concentration of calcium in the cell at that time. | 1 | Gene expression + Signal Transduction |
Iron plantations were rural localities emergent in the late-18th century and predominant in the early-19th century that specialized in the production of pig iron and bar iron from crude iron ore.
Such plantations derive their name from two sources. First, because they were nearly self-sufficient communities despite an almost singular focus on the production of iron to be sold on the market, and second, because of the large swaths of forest and land necessary to provide charcoal fuel and ore for their operations.
The first plantations stretched across the Northeast, Midwest, and Southern United States, "the chief charcoal iron producing states [being] Pennsylvania, Ohio, New York, Virginia, Connecticut, Maryland, Missouri, Tennessee, and Kentucky." Many produced raw materials used in the American Revolution or to be exported to England.
For the rest of the 19th century, however, only locations that adopted new technologies first introduced by competing coal- and coke-powered smelters in the rapidly industrializing field persisted. | 0 | Metallurgy |
Variants of the genes can cause several relatively rare forms of MODY, an inherited, early onset form of diabetes. Mutations in the HNF4α, HNF1α, or HNF1β genes are linked to MODY 1, MODY 3, and MODY 5 respectively. Mutations in HNF genes are also associated with a number of others diseases including hepatic adenomas and renal cysts. | 1 | Gene expression + Signal Transduction |
Organic fluxes typically consist of four major components:
* Activators – chemicals disrupting/dissolving the metal oxides. Their role is to expose unoxidized, easily wettable metal surface and aid soldering by other means, e.g. by exchange reactions with the base metals.
** Highly active fluxes contain chemicals that are corrosive at room temperature. The compounds used include metal halides (most often zinc chloride or ammonium chloride), hydrochloric acid, phosphoric acid, citric acid, and hydrobromic acid. Salts of mineral acids with amines are also used as aggressive activators. Aggressive fluxes typically facilitate corrosion, require careful removal, and are unsuitable for finer work. Activators for fluxes for soldering and brazing aluminium often contain fluorides.
** Milder activators begin to react with oxides only at elevated temperature. Typical compounds used are carboxylic acids (e.g. fatty acids (most often oleic acid and stearic acid), dicarboxylic acids) and sometimes amino acids. Some milder fluxes also contain halides or organohalides.
* Vehicles – high-temperature tolerant chemicals in the form of non-volatile liquids or solids with suitable melting point; they are generally liquid at soldering temperatures. Their role is to act as an oxygen barrier to protect the hot metal surface against oxidation, to dissolve the reaction products of activators and oxides and carry them away from the metal surface, and to facilitate heat transfer. Solid vehicles tend to be based on natural or modified rosin (mostly abietic acid, pimaric acid, and other resin acids) or natural or synthetic resins. Water-soluble organic fluxes tend to contain vehicles based on high-boiling polyols - glycols, diethylene glycol and higher polyglycols, polyglycol-based surfactants and glycerol.
* Solvents – added to facilitate processing and deposition to the joint. Solvents are typically dried out during preheating before the soldering operation; incomplete solvent removal may lead to boiling off and spattering of solder paste particles or molten solder.
* Additives – numerous other chemicals modifying the flux properties. Additives can be surfactants (especially nonionic), corrosion inhibitors, stabilizers and antioxidants, tackifiers, thickeners and other rheological modifiers (especially for solder pastes), plasticizers (especially for flux-cored solders), and dyes. | 0 | Metallurgy |
The Imd pathway is a broadly-conserved NF-κB immune signalling pathway of insects and some arthropods that regulates a potent antibacterial defence response. The pathway is named after the discovery of a mutation causing severe immune deficiency (the gene was named "Imd" for "immune deficiency"). The Imd pathway was first discovered in 1995 using Drosophila fruit flies by Bruno Lemaitre and colleagues, who also later discovered that the Drosophila Toll gene regulated defence against Gram-positive bacteria and fungi. Together the Toll and Imd pathways have formed a paradigm of insect immune signalling; as of September 2, 2019, these two landmark discovery papers have been cited collectively over 5000 times since publication on Google Scholar.
The Imd pathway responds to signals produced by Gram-negative bacteria. Peptidoglycan recognition proteins (PGRPs) sense DAP-type peptidoglycan, which activates the Imd signalling cascade. This culminates in the translocation of the NF-κB transcription factor Relish, leading to production of antimicrobial peptides and other effectors. Insects lacking Imd signalling either naturally or by genetic manipulation are extremely susceptible to infection by a wide variety of pathogens and especially bacteria. | 1 | Gene expression + Signal Transduction |
The chemical reaction for the dissolution of gold, the "Elsner equation", follows:
: 4Au + 8NaCN + O + 2HO → 4Na[Au(CN)] + 4NaOH
Potassium cyanide and calcium cyanide are sometimes used in place of sodium cyanide.
Gold is one of the few metals that dissolves in the presence of cyanide ions and oxygen. The soluble gold species is dicyanoaurate. from which it can be recovered by adsorption onto activated carbon. | 0 | Metallurgy |
After-rust is a form of rust which sometimes develops on a non-ferrous metal surface when that surface has been finished, deburred, or cleaned with a carbon steel brush or steel wool. It is caused by microscopic deposits of the steel which become embedded in the metal surface and which over time begin to oxidize. This oxidation causes the surface to become dull and may impart a brown color to it. After-rust can be avoided by cleaning such surfaces only with non-ferrous brushes/ wools including rustless bronze, aluminum, and stainless steel wool and nonferrous wools such as those made of brass. | 0 | Metallurgy |
The waste product was allowed to cool in the hearth and removed as a "mosser". In the Furness district they were often left as the capstone of a wall, particularly near Spark Bridge and Nibthwaite forges. | 0 | Metallurgy |
The working of memorial brasses is generally considered to have originated in north-western Germany, at least one centre being Cologne, where were manufactured the latten or Cullen plates for local use and for exportation. But it is certain that from medieval times there was an equal production in the towns of Belgium, when brass was the favoured metal for other purposes. Continental brasses were of rectangular sheets of metal on which the figure of the deceased was represented, up to life-size, by deeply incised lines, frequently filled with mastic or enamel-like substance; the background of the figures was covered with an architectural setting, or with ornament of foliage and figures, and an inscription. In England, possibly because the metal was less plentiful, the figures are usually accessories, being cut out of the metal and inserted in the matrices of stone or marble slabs which form part of the tomb; architectural canopies, inscriptions and shields of arms are affixed in the same way. Thus the stone or marble background takes the place of the decorated brass background of the Continental example. The early method of filling in the incisions has suggested some connection with the methods of the Limoges enamellers of the 13th century. The art was introduced into England from the Low Countries, and speedily attained a high degree of excellence. For many centuries it remained very popular, and a large number of brasses still remain to witness to a very beautiful department of artistic working.
The earliest existing brass is that of Bishop Ysowilpe at Verden, in Germany, which dates from 1231 and is on the model of an incised stone, as if by an artist accustomed to work in that material. In England the oldest example is at Stoke DAbernon church, in Surrey, to the memory of Sir John DAbernon, who died in 1277. Numerous brasses are to be found in Belgium, and some in France and the Netherlands. Apart from their artistic attractiveness, these ornamental brasses are of the utmost value in faithfully depicting the costumes of the period, ecclesiastical, civil or military; they furnish also appropriate inscriptions in beautiful lettering (cf. Brass Gallery). | 0 | Metallurgy |
Although gas handling and processing are far more economical than converting coal into coke (not to mention the associated constraints, such as bulk handling, high sensitivity of coking plants to production fluctuations, environmental impact, etc.), replacing coke with natural gas only makes direct reduction attractive to steelmakers with cheap gas resources. This point is essential, as European steelmakers pointed out in 1998:This explains the development of certain reduction-melting processes which, because of the high temperatures involved, have a surplus of reducing gas. Reduction-melting processes such as the COREX, capable of feeding an ancillary Midrex direct reduction unit, or the Tecnored, are justified by their ability to produce CO-rich gas despite their higher investment cost. In addition, coke oven gas is an essential co-product in the energy strategy of a steel complex: the absence of a coke oven must therefore be compensated for by higher natural gas consumption for downstream tools, notably hot rolling and annealing furnaces.
The worldwide distribution of direct reduction plants is therefore directly correlated with the availability of natural gas and ore. In 2007, the breakdown was as follows:
* natural gas processes are concentrated in Latin America (where many have already been developed) and the Middle East;
* coal-fired processes are remarkably successful in India, maintaining the proportion of steel produced by direct reduction despite the strong development of the Chinese steel industry.
China, a country with gigantic needs and a deficit of scrap metal, and Europe, lacking competitive ore and fuels, have never invested massively in these processes, remaining faithful to the blast furnace route. The United States, meanwhile, has always had a few units, but since 2012, the exploitation of shale gas has given a new impetus to natural gas processes.
However, because direct reduction uses much more hydrogen as a reducing agent than blast furnaces (which is very clear for natural gas processes), it produces much less CO, a greenhouse gas. This advantage has motivated the development of ULCOS processes in developed countries, such as HISARNA, ULCORED, and others. The emergence of mature gas treatment technologies, such as pressure swing adsorption or amine gas treating, has also rekindled the interest of researchers. In addition to reducing CO emissions, pure hydrogen processes such as Hybrit are being actively studied with a view to decarbonizing the steel industry. | 0 | Metallurgy |
Active mTORC1 is positioned on lysosomes. mTOR is inhibited when lysosomal membrane is damaged by various exogenous or endogenous agents, such as invading bacteria, membrane-permeant chemicals yielding osmotically active products (this type of injury can be modeled using membrane-permeant dipeptide precursors that polymerize in lysosomes), amyloid protein aggregates (see above section on Alzheimers disease) and cytoplasmic organic or inorganic inclusions including urate crystals and crystalline silica. The process of mTOR inactivation following lysosomal/endomembrane is mediated by the protein complex termed GALTOR. At the heart of GALTOR is galectin-8, a member of β-galactoside binding superfamily of cytosolic lectins termed galectins, which recognizes lysosomal membrane damage by binding to the exposed glycans on the lumenal side of the delimiting endomembrane. Following membrane damage, galectin-8, which normally associates with mTOR under homeostatic conditions, no longer interacts with mTOR but now instead binds to SLC38A9, RRAGA/RRAGB, and LAMTOR1, inhibiting Ragulators (LAMTOR1-5 complex) guanine nucleotide exchange function-
TOR is a negative regulator of autophagy in general, best studied during response to starvation, which is a metabolic response. During lysosomal damage however, mTOR inhibition activates autophagy response in its quality control function, leading to the process termed lysophagy that removes damaged lysosomes. At this stage another galectin, galectin-3, interacts with TRIM16 to guide selective autophagy of damaged lysosomes. TRIM16 gathers ULK1 and principal components (Beclin 1 and ATG16L1) of other complexes (Beclin 1-VPS34-ATG14 and ATG16L1-ATG5-ATG12) initiating autophagy, many of them being under negative control of mTOR directly such as the ULK1-ATG13 complex, or indirectly, such as components of the class III PI3K (Beclin 1, ATG14 and VPS34) since they depend on activating phosphorylations by ULK1 when it is not inhibited by mTOR. These autophagy-driving components physically and functionally link up with each other integrating all processes necessary for autophagosomal formation: (i) the ULK1-ATG13-FIP200/RB1CC1 complex associates with the LC3B/GABARAP conjugation machinery through direct interactions between FIP200/RB1CC1 and ATG16L1, (ii) ULK1-ATG13-FIP200/RB1CC1 complex associates with the Beclin 1-VPS34-ATG14 via direct interactions between ATG13's HORMA domain and ATG14, (iii) ATG16L1 interacts with WIPI2, which binds to PI3P, the enzymatic product of the class III PI3K Beclin 1-VPS34-ATG14. Thus, mTOR inactivation, initiated through GALTOR upon lysosomal damage, plus a simultaneous activation via galectin-9 (which also recognizes lysosomal membrane breach) of AMPK that directly phosphorylates and activates key components (ULK1, Beclin 1) of the autophagy systems listed above and further inactivates mTORC1, allows for strong autophagy induction and autophagic removal of damaged lysosomes.
Additionally, several types of ubiquitination events parallel and complement the galectin-driven processes: Ubiquitination of TRIM16-ULK1-Beclin-1 stabilizes these complexes to promote autophagy activation as described above. ATG16L1 has an intrinsic binding affinity for ubiquitin); whereas ubiquitination by a glycoprotein-specific FBXO27-endowed ubiquitin ligase of several damage-exposed glycosylated lysosomal membrane proteins such as LAMP1, LAMP2, GNS/N-acetylglucosamine-6-sulfatase, TSPAN6/tetraspanin-6, PSAP/prosaposin, and TMEM192/transmembrane protein 192 may contribute to the execution of lysophagy via autophagic receptors such as p62/SQSTM1, which is recruited during lysophagy, or other to be determined functions. | 1 | Gene expression + Signal Transduction |
The Hall-Héroult electrolysis process is the major production route for primary aluminium. An electrolytic cell is made of a steel shell with a series of insulating linings of refractory materials. The cell consists of a brick-lined outer steel shell as a container and support. Inside the shell, cathode blocks are cemented together by ramming paste. The top lining is in contact with the molten metal and acts as the cathode. The molten electrolyte is maintained at high temperature inside the cell. The prebaked anode is also made of carbon in the form of large sintered blocks suspended in the electrolyte. A single Soderberg electrode or a number of prebaked carbon blocks are used as anode, while the principal formulation and the fundamental reactions occurring on their surface are the same.
An aluminium smelter consists of a large number of cells (pots) in which the electrolysis takes place. A typical smelter contains anywhere from 300 to 720 pots, each of which produces about a ton of aluminium a day, though the largest proposed smelters are up to five times that capacity. Smelting is run as a batch process, with the aluminium deposited at the bottom of the pots and periodically siphoned off. Particularly in Australia these smelters are used to control electrical network demand, and as a result power is supplied to the smelter at a very low price. However power must not be interrupted for more than 4–5 hours, since the pots have to be repaired at significant cost if the liquid metal solidifies. | 0 | Metallurgy |
The Reactor Materials Laboratory was established at Culcheth in 1950. The UKAEA's Safety and Reliability Directorate (SRD) stayed at Culcheth until 1995. | 0 | Metallurgy |
DNA methylation involves the addition of a methyl group to the carbon-5 position of the cytosine ring in the CpG dinucleotide and converting it to methylcytosine. This process is catalyzed by DNA methyltransferase. In numerous cancers, the CpG islands of selected genes are aberrantly methylated (hypermethylated) which results in transcriptional repression. This may be an alternate mechanism of gene inactivation.
Multiple genes have been discovered to be frequently methylated in cancers and leukemias. More specifically, the deregulation of the Wnt signaling pathway has been implicated in a wide array of cancers that is mainly seen as a result of loss-of-function mutations of APC and axin or as a gain-of-function mutation of CTNNB1 (B-catenin). The GC content of the SFRP1 promoter in humans is 56.3%.
It has been found that the overexpression of B-catenin may lead to enhanced proliferation in myeloma plasma cells; thus, soluble Wnt inhibitors are potential tumor suppressor genes and, if inactivated, may contribute to myeloma pathogenesis. This led Chim et al. to investigate the role of aberrant gene methylation of a panel of soluble Wnt antagonists, including SFRP1. Complete methylation led to silencing of respective genes (no transcripts), whereas absence of gene methylation was associated with constitutive gene expression. Methylation of soluble Wnt antagonists would be important in the pathogenesis of multiple myeloma if Wnt signaling was regulated by an autocrine loop by Wnt and Fz. If an autocrine loops exists, then both the ligand (Wz) and receptor (Fzd) should be simultaneously expressed in myeloma cells and growth of tumour cells should be inhibited upon addition of SFRP1. Chim et al. demonstrated simultaneous expression of Wz and Fzd in myeloma plasma cells. Moreover, treatment with recombinant SFRP1 inhibited the growth of myeloma cells in a dose-dependent manner. These findings implicate soluble Wnt inhibitors as tumor suppressors that could be inactivated by methylation.
Veeck and colleagues found all of their eight breast cancer cell lines had complete methylation in the SFRP1 promoter region, while no methylation was detectable in non-malignant cell lines. After treatment with 5-Aza-2’-deoxycytidine (DAC), an inhibitor of DNA methyltransferase, SFRP1 expression was restored in all four treated breast cancer cell lines, supporting the hypothesis of methylation-mediated SFRP1 gene silencing in breast cancer.
Furthermore, the transcriptional silencing mechanism underlying DNA methylation which is brought about through the hypermethylation of CpG-rich islands present in the promoter region of genes, can cooperate with histone deacetylation to change chromatin structure to a repressed form. Lo and colleagues looked at the effects of DAC and trichostatin A (TSA, selectively inhibits the mammalian histone deacetylase family of enzymes) on cancer cells. In 4 breast cancer cell lines, SFRP1 expression was significantly restored after treatment with DAC alone. TSA, only in combination with DAC, had a slightly enhanced effect on SFRP1 expression in these cell lines. A different breast cancer cell line (SKBR3, showed loss of SFRP1 expression without significant methylation of the SFRP1 promoter. Lo et al. hypothesized that this may be due to silencing via histone deacetylation. After SKBR3 cells were treated with TSA, SFRP1 expression was restored in a dose- and time-dependent manner. Yet another breast cancer cell line (T47D) required both DAC and TSA to upregulate SFRP1 expression. This indicates that T47D cells are tightly regulated by two layers of epigenetic control (DNA methylation and histion deacetylation) and relieving inhibition by both mechanisms is necessary for reactivation of SFRP1. This study shows that both the epigenetic mechanisms, DNA methylation and histone deacetylation, are involved in silencing of SFRP1. | 1 | Gene expression + Signal Transduction |
Calcination is thermal decomposition of a material. Examples include decomposition of hydrates such as ferric hydroxide to ferric oxide and water vapor, the decomposition of calcium carbonate to calcium oxide and carbon dioxide as well as iron carbonate to iron oxide:
:CaCO → CaO + CO
Calcination processes are carried out in a variety of furnaces, including shaft furnaces, rotary kilns, and fluidized bed reactors. | 0 | Metallurgy |
While most genes of E. coli can be recognized by an RNAP with one and only one type of sigma factor (e.g. sigma 70), a few genes (~ 5%) have what is called a “dual sigma factor preference”, that is, they can respond to two different sigma factors, as reported in RegulonDB. The most common ones are those promoters that can respond to both sigma 70 and to sigma 38 (iIlustrated in the figure) . Studies of the dynamics of these genes showed that when the cells enter stationary growth they are almost as induced as those genes that have preference for σ38 alone. This induction level was shown to be predictable from their promoter sequence. A model of their dynamics is shown in the figure. In the future, these promoters may become useful tools in synthetic genetic constructs in E. coli. | 1 | Gene expression + Signal Transduction |
Mustafa Babanlı (; born February 21, 1968), is an Azerbaijani scientist, Rector of the Azerbaijan State Oil and Industry University.
On September 3, 2015, Mustafa Babanli was appointed Rector of the Azerbaijan State University of Oil and Industry. He is a member of the International Association of University Presidents, serving as Regional Chair for Middle East, Caucasus & Central Asia. | 0 | Metallurgy |
There are several PREN formulas. They commonly range from:
: PREN = %Cr + 3.3 × %Mo + 16 × %N
to:
: PREN = %Cr + 3.3 × %Mo + 30 × %N.
There are a few stainless steels which add tungsten (W), for those the following formula is used:
: PREN = %Cr + 3.3 × (%Mo + 0.5 × %W ) + 16 × %N
All % values of elements must be expressed by mass, or weight (wt. %), and not by volume. Tolerance on element measurements could be ignored as the PREN value is indicative only. | 0 | Metallurgy |
Window shutter hardware, usually made of iron, are hinges and latches that attach to the shutter and a window frame (and in some cases directly attached to stone or brick). The hinges hold the shutter to the structure and allow the shutter to open and close over the window. The latches secure the shutter in the closed (over the window) position. Tie-back hardware can be used to hold the shutter in the open position.
Exterior shutters were vital elements of homes in the colonies. Raised panel shutters provided security against access from ground level. Exterior shutters also proved a first barrier against the elements. In cities, shutters provided privacy screens for the residents. Louvered upstairs shutters were often later additions to the home.
This article describes the evolution of early exterior window shutter hardware, terms and terminology related to shutter hardware and blacksmithing, and American regional styles of installation. | 0 | Metallurgy |
The allosteric model suggests that termination occurs due to the structural change of the RNA polymerase unit after binding to or losing some of its associated proteins, making it detach from the DNA strand after the signal. This would occur after the RNA pol II unit has transcribed the poly-A signal sequence, which acts as a terminator signal.
RNA polymerase is normally capable of transcribing DNA into single-stranded mRNA efficiently. However, upon transcribing over the poly-A signals on the DNA template, a conformational shift is induced in the RNA polymerase from the proposed loss of associated proteins from its carboxyl terminal domain. This change of conformation reduces RNA polymerase's processivity making the enzyme more prone to dissociating from its DNA-RNA substrate. In this case, termination is not completed by degradation of mRNA but instead is mediated by limiting the elongation efficiency of RNA polymerase and thus increasing the likelihood that the polymerase will dissociate and end its current cycle of transcription. | 1 | Gene expression + Signal Transduction |
Corrosion inhibitors, such as gas-phase or volatile inhibitors, can be used to prevent corrosion inside sealed systems. They are not effective when air circulation disperses them, and brings in fresh oxygen and moisture. | 0 | Metallurgy |
In northern Europe, France, Germany, England and the Netherlands, bellfounding has been an enormous industry since the early part of the Middle Ages. Unfortunately a large number of medieval bells have been melted down and recast, and in times of warfare many were seized to be cast into guns. Early bells are of graceful outline, and often have simple but well-designed ornaments and very decorative inscriptions; for the latter a separate stamp or die was used for each letter or for a short group of letters. In every country bell-founders were an important group of the community; in England a great many of their names are known and the special character of their work is recognizable. Old bells exist in the French cathedrals of Amiens, Beauvais, Chartres and elsewhere; in Germany at Erfurt, Cologne and Halberstadt. The bell-founding industry has continued all through the centuries, one of its later achievements being the casting of "Big Ben" at Westminster in 1858, a bell of between 13 and 14 tons in weight.
In more recent years, bronze has to some extent replaced iron for railings, balconies and staircases, in connection with architecture; the style adopted is stiffly classical, which does not call for a very large amount of ornamentation, and the metal has the merit of pleasant appearance and considerable durability. | 0 | Metallurgy |
There are several options to address biogenic sulfide corrosion problems: impairing HS formation, venting out the HS or using materials resistant to biogenic corrosion. For example, sewage flows more rapidly through steeper gradient sewers reducing time available for hydrogen sulfide generation. Likewise, removing sludge and sediments from the bottom of the pipes reduces the amount of anoxic areas responsible for sulfate reducing bacteria growth. Providing good ventilation of sewers can reduce atmospheric concentrations of hydrogen sulfide gas and may dry exposed sewer crowns, but this may create odor issues with neighbors around the venting shafts. Three other efficient methods can be used involving continuous operation of mechanical equipment: chemical reactant like calcium nitrate can be continuously added in the sewerage water to impair the HS formation, an active ventilation through odor treatment units to remove HS, or an injection of compressed air in pressurized mains to avoid the anaerobic condition to develop. In sewerage areas where biogenic sulfide corrosion is expected, acid resistant materials like calcium aluminate cements, PVC or vitrified clay pipe may be substituted to ordinary concrete or steel sewers.
Existing structures that have extensive exposure to biogenic corrosion such as sewer manholes and pump station wet wells can be rehabilitated. Rehabilitation can be done with materials such as a structural epoxy coating, this epoxy is designed to be both acid resistant and strengthen the compromised concrete structure. | 0 | Metallurgy |
The Downs cell uses a carbon anode and an iron cathode. The electrolyte is sodium chloride that has been heated to the liquid state. Although solid sodium chloride is a poor conductor of electricity, when molten the sodium and chloride ions are mobilized, which become charge carriers and allow conduction of electric current.
Some calcium chloride and/or chlorides of barium (BaCl) and strontium (SrCl), and, in some processes, sodium fluoride (NaF) are added to the electrolyte to reduce the temperature required to keep the electrolyte liquid. Sodium chloride (NaCl) melts at 801 °C (1074 Kelvin), but a salt mixture can be kept liquid at a temperature as low as 600 °C at the mixture containing, by weight: 33.2% NaCl and 66.8% CaCl. If pure sodium chloride is used, a metallic sodium emulsion is formed in the molten NaCl which is impossible to separate. Therefore, one option is to have a NaCl (42%) and CaCl (58%) mixture.
The anode reaction is:
: 2Cl → Cl (g) + 2e
The cathode reaction is:
: 2Na + 2e → 2Na (l)
for an overall reaction of
: 2Na + 2Cl → 2Na (l) + Cl (g)
The calcium does not enter into the reaction because its reduction potential of -2.87 volts is lower than that of sodium, which is -2.38 volts. Hence the sodium ions are reduced to metallic form in preference to those of calcium. If the electrolyte contained only calcium ions and no sodium, calcium metal would be produced as the cathode product (which indeed is how metallic calcium is produced).
Both the products of the electrolysis, sodium metal and chlorine gas, are less dense than the electrolyte and therefore float to the surface. Perforated iron baffles are arranged in the cell to direct the products into separate chambers without their ever coming into contact with each other.
Although theory predicts that a potential of a little over 4.07 volts should be sufficient to cause the reaction to go forward, in practice potentials of up to 8 volts are used. This is done in order to achieve useful current densities in the electrolyte despite its inherent electrical resistance. The overvoltage and consequent resistive heating contributes to the heat required to keep the electrolyte in a liquid state.
The Downs' process also produces chlorine as a byproduct, although chlorine produced this way accounts for only a small fraction of chlorine produced industrially by other methods. | 0 | Metallurgy |
K-Mold is a fracture test method. Liquid metal is cast into a mold containing notches. Once solidified, the resulting bar is bent to expose a fracture surface. The visual observation of inclusions on the fracture is used to determine a K-value for the melt and compared to a preset standard. This method is rather imprecise and therefore only suitable when metal contains large inclusions and inclusion clusters. | 0 | Metallurgy |
Recently, a well-studied quorum quenching bacterial strain (KM1S) was isolated and its AHL degradation kinetics were studied using rapid resolution liquid chromatography (RRLC). RRLC efficiently separates components of a mixture to a high degree of sensitivity, based on their affinities for different liquid phases. It was found that the genome of this strain encoded an inactivation enzyme with distinct motifs targeting the degradation of AHLs. | 1 | Gene expression + Signal Transduction |
The TET enzymes are a family of ten-eleven translocation (TET) methylcytosine dioxygenases. They are instrumental in DNA demethylation. 5-Methylcytosine (see first Figure) is a methylated form of the DNA base cytosine (C) that often regulates gene transcription and has several other functions in the genome.
Demethylation by TET enzymes (see second Figure), can alter the regulation of transcription. The TET enzymes catalyze the hydroxylation of DNA 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), and can further catalyse oxidation of 5hmC to 5-formylcytosine (5fC) and then to 5-carboxycytosine (5caC). 5fC and 5caC can be removed from the DNA base sequence by base excision repair and replaced by cytosine in the base sequence.
TET enzymes have central roles in DNA demethylation required during embryogenesis, gametogenesis, memory, learning, addiction and pain perception. | 1 | Gene expression + Signal Transduction |
The purpose of heat treating carbon steel is to change the mechanical properties of steel, usually ductility, hardness, yield strength, or impact resistance. Note that the electrical and thermal conductivity are only slightly altered. As with most strengthening techniques for steel, Young's modulus (elasticity) is unaffected. All treatments of steel trade ductility for increased strength and vice versa. Iron has a higher solubility for carbon in the austenite phase; therefore all heat treatments, except spheroidizing and process annealing, start by heating the steel to a temperature at which the austenitic phase can exist. The steel is then quenched (heat drawn out) at a moderate to low rate allowing carbon to diffuse out of the austenite forming iron-carbide (cementite) and leaving ferrite, or at a high rate, trapping the carbon within the iron thus forming martensite. The rate at which the steel is cooled through the eutectoid temperature (about ) affects the rate at which carbon diffuses out of austenite and forms cementite. Generally speaking, cooling swiftly will leave iron carbide finely dispersed and produce a fine grained pearlite and cooling slowly will give a coarser pearlite. Cooling a hypoeutectoid steel (less than 0.77 wt% C) results in a lamellar-pearlitic structure of iron carbide layers with α-ferrite (nearly pure iron) between. If it is hypereutectoid steel (more than 0.77 wt% C) then the structure is full pearlite with small grains (larger than the pearlite lamella) of cementite formed on the grain boundaries. A eutectoid steel (0.77% carbon) will have a pearlite structure throughout the grains with no cementite at the boundaries. The relative amounts of constituents are found using the lever rule. The following is a list of the types of heat treatments possible:
; Spheroidizing: Spheroidite forms when carbon steel is heated to approximately for over 30 hours. Spheroidite can form at lower temperatures but the time needed drastically increases, as this is a diffusion-controlled process. The result is a structure of rods or spheres of cementite within primary structure (ferrite or pearlite, depending on which side of the eutectoid you are on). The purpose is to soften higher carbon steels and allow more formability. This is the softest and most ductile form of steel.
; Full annealing: Carbon steel is heated to approximately for 1 hour; this ensures all the ferrite transforms into austenite (although cementite might still exist if the carbon content is greater than the eutectoid). The steel must then be cooled slowly, in the realm of 20 °C (36 °F) per hour. Usually it is just furnace cooled, where the furnace is turned off with the steel still inside. This results in a coarse pearlitic structure, which means the "bands" of pearlite are thick. Fully annealed steel is soft and ductile, with no internal stresses, which is often necessary for cost-effective forming. Only spheroidized steel is softer and more ductile.
; Process annealing: A process used to relieve stress in a cold-worked carbon steel with less than 0.3% C. The steel is usually heated to for 1 hour, but sometimes temperatures as high as . The image above shows the process annealing area.
; Isothermal annealing: It is a process in which hypoeutectoid steel is heated above the upper critical temperature. This temperature is maintained for a time and then reduced to below the lower critical temperature and is again maintained. It is then cooled to room temperature. This method eliminates any temperature gradient.
; Normalizing: Carbon steel is heated to approximately for 1 hour; this ensures the steel completely transforms to austenite. The steel is then air-cooled, which is a cooling rate of approximately per minute. This results in a fine pearlitic structure, and a more-uniform structure. Normalized steel has a higher strength than annealed steel; it has a relatively high strength and hardness.
; Quenching: Carbon steel with at least 0.4 wt% C is heated to normalizing temperatures and then rapidly cooled (quenched) in water, brine, or oil to the critical temperature. The critical temperature is dependent on the carbon content, but as a general rule is lower as the carbon content increases. This results in a martensitic structure; a form of steel that possesses a super-saturated carbon content in a deformed body-centered cubic (BCC) crystalline structure, properly termed body-centered tetragonal (BCT), with much internal stress. Thus quenched steel is extremely hard but brittle, usually too brittle for practical purposes. These internal stresses may cause stress cracks on the surface. Quenched steel is approximately three times harder (four with more carbon) than normalized steel.
; Martempering (marquenching): Martempering is not actually a tempering procedure, hence the term marquenching. It is a form of isothermal heat treatment applied after an initial quench, typically in a molten salt bath, at a temperature just above the "martensite start temperature". At this temperature, residual stresses within the material are relieved and some bainite may be formed from the retained austenite which did not have time to transform into anything else. In industry, this is a process used to control the ductility and hardness of a material. With longer marquenching, the ductility increases with a minimal loss in strength; the steel is held in this solution until the inner and outer temperatures of the part equalize. Then the steel is cooled at a moderate speed to keep the temperature gradient minimal. Not only does this process reduce internal stresses and stress cracks, but it also increases impact resistance.
; Tempering: This is the most common heat treatment encountered because the final properties can be precisely determined by the temperature and time of the tempering. Tempering involves reheating quenched steel to a temperature below the eutectoid temperature and then cooling. The elevated temperature allows very small amounts spheroidite to form, which restores ductility but reduces hardness. Actual temperatures and times are carefully chosen for each composition.
; Austempering: The austempering process is the same as martempering, except the quench is interrupted and the steel is held in the molten salt bath at temperatures between , and then cooled at a moderate rate. The resulting steel, called bainite, produces an acicular microstructure in the steel that has great strength (but less than martensite), greater ductility, higher impact resistance, and less distortion than martensite steel. The disadvantage of austempering is it can be used only on a few sheets of steel, and it requires a special salt bath. | 0 | Metallurgy |
Molten salts (fluoride, chloride, and nitrate) can be used as heat transfer fluids as well as for thermal storage. This thermal storage is used in concentrated solar power plants.
Molten-salt reactors are a type of nuclear reactor that uses molten salt(s) as a coolant or as a solvent in which the fissile material is dissolved. Experimental salts using lithium can be formed that have a melting point of 116 °C while still having a heat capacity of 1.54 J/(g·K). | 0 | Metallurgy |
While most mining companies have shifted from a previously accepted sprinkler method to the percolation of slowly dripping choice chemicals including cyanide or sulfuric acid closer to the actual ore bed, heap leach pads have not changed too much throughout the years. There are still four main categories of pads: conventional, dump leach, valley fills, and on/off pads. Typically, each pad only has a single, geomembrane liner for each pad, with a minimum thickness of 1.5mm, usually thicker.
The conventional pads simplest in design are used for mostly flat or gentle areas and hold thinner layers of crushed ore. Dump leach pads hold more ore and can usually handle a less flat terrain. Valley fills are pads situated at valley bottoms or levels that can hold everything falling into it. On/off pads involve putting significantly larger loads on the pads and removing and reloading it after every cycle.
Many of these mines which previously had digging depths of about 15 meters are digging deeper than ever before to mine materials, approximately 50 meters, sometimes more, which means that, in order to accommodate all of the ground being displaced, pads will have to hold higher weights from more crushed ore being contained in a smaller area (Lupo 2010). With that increase in build up comes in potential for decrease in yield or ore quality, as well as potential either weak spots in the lining or areas of increased pressure buildup. This build up still has the potential to lead to punctures in the liner. As of 2004 cushion fabrics, which could reduce potential punctures and their leaking, were still being debated due to their tendency to increase risks if too much weight on too large a surface was placed on the cushioning (Thiel and Smith 2004). In addition, some liners, depending on their composition, may react with salts in the soil as well as acid from the chemical leaching to affect the successfulness of the liner. This can be amplified over time. | 0 | Metallurgy |
Bronze statuettes were also made in every period of antiquity for votive use, and at least in Hellenistic and Roman times for domestic ornaments and furniture of household shrines. But the art of bronze statuary hardly existed before the introduction of hollow casting, about the middle of the 6th century BC. The most primitive votive statuettes are oxen and other animals, which evidently represent victims offered to the gods. They have been found abundantly on many temple sites. But classical art preferred the human subject, votaries holding gifts or in their ordinary guise, or gods themselves in human form. Such figures are frequently inscribed with formulas of dedication. Gods and goddesses posed conformably with their traditional characters and bearing their distinctive attributes are the most numerously represented class of later statuettes. They are a religious genre, appearing first in 4th-century sculpture and particularly favoured by Hellenistic sentiment and Roman pedantry. Many of them were doubtless votive figures, others were images in domestic shrines, and some were certainly ornaments. Among the cult-idols are the dancing Lares, who carry cornucopias and libation-bowls. The little Heracles that Lysippus made for Alexander was a table-ornament (epitrapezios): he was reclining on the lion's skin, his club in one hand, a wine-cup in the other. | 0 | Metallurgy |
During high-energy milling the powder particles are repeatedly flattened, cold welded, fractured and rewelded. Whenever two steel balls collide, some powder is trapped between them. Typically, around 1000 particles with an aggregate weight of about 0.2 mg are trapped during each collision. The force of the impact plastically deforms the powder particles, leading to work hardening and fracture. The new surfaces thus created enable the particles to weld together; this leads to an increase in particle size. Since in the early stages of milling, the particles are soft (if using either ductile-ductile or ductile-brittle material combination), their tendency to weld together and form large particles is high. A broad range of particle sizes develops, with some as large as three times larger than the starting particles. The composite particles at this stage have a characteristic layered structure consisting of various combinations of the starting constituents. With continued deformation particles become work hardened, and fracture by a fatigue failure mechanism and/or by the fragmentation of fragile flakes. | 0 | Metallurgy |
If water is left to stand in a tube for an extended period, the chemical characteristics of the water change as the mixed scale and corrosion products are deposited. In addition any loose scale that is not well adhered to the wall will not be flushed away and air dissolved in the water will form bubbles, producing air pockets. These processes can lead to a number of problems mainly on horizontal tube runs. Particles of scale that do not adhere to the walls and are not washed away tend to fall into the bottom of the tube producing a coarse porous deposit. Air pockets that develop in horizontal runs disrupt the formation of protective scales in two areas: the water lines at the sides, and the air space at the top of the tube.
In each of the areas that the scale has been disrupted there is the possibility of the initiation of Type 1 pitting. Once pitting has initiated, then even after the tube has been put back into service, the pit will continue to develop until the wall has perforated. This form of attack is often associated with the commissioning of a system. Once a system has been commissioned it should be either put immediately into service or drained down and dried by flushing with compressed air otherwise pitting may initiate. If either of these options is not possible then the system should be flushed through regularly until it is put into use. | 0 | Metallurgy |
Converting is a type of metallurgical smelting that includes several processes; the most commercially important form is the treatment of molten metal sulfides to produce crude metal and slag, as in the case of copper and nickel converting. A now-uncommon form is batch treatment of pig iron to produce steel by the Bessemer process. The vessel used was called the Bessemer converter. Modern steel mills use basic oxygen process converters. | 0 | Metallurgy |
The amorphous material produced by melt spinning is considered a soft magnet. That is to say that their natural coercivity is less than 1000 Am-1, which means that the metal's magnetism is more responsive to outside influences and as a result can be easily switched on and off. This makes amorphous metals particularly useful in applications requiring the repeated magnetization and demagnetization of a material in order to function. Certain amorphous alloys also provide the ability to enhance and or channel flux created by electrical currents, making them useful for magnetic shielding and insulation.
The exact magnetic properties of each alloy depend mostly on the atomic composition of the material. For example, nickel-iron alloys with a lower amount of nickel have a high electrical resistance, while those with a higher percentage of nickel have a high magnetic permeability. | 0 | Metallurgy |
Recent experimental results
have demonstrated that gene expression is a stochastic process. Thus, many authors are now using the stochastic formalism, after the work by Arkin et al. Works on single gene expression and small synthetic genetic networks, such as the genetic toggle switch of Tim Gardner and Jim Collins, provided additional experimental data on the phenotypic variability and the stochastic nature of gene expression. The first versions of stochastic models of gene expression involved only instantaneous reactions and were driven by the Gillespie algorithm.
Since some processes, such as gene transcription, involve many reactions and could not be correctly modeled as an instantaneous reaction in a single step, it was proposed to model these reactions as single step multiple delayed reactions in order to account for the time it takes for the entire process to be complete.
From here, a set of reactions were proposed that allow generating GRNs. These are then simulated using a modified version of the Gillespie algorithm, that can simulate multiple time delayed reactions (chemical reactions where each of the products is provided a time delay that determines when will it be released in the system as a "finished product").
For example, basic transcription of a gene can be represented by the following single-step reaction (RNAP is the RNA polymerase, RBS is the RNA ribosome binding site, and Pro is the promoter region of gene i):
Furthermore, there seems to be a trade-off between the noise in gene expression, the speed with which genes can switch, and the metabolic cost associated their functioning. More specifically, for any given level of metabolic cost, there is an optimal trade-off between noise and processing speed and increasing the metabolic cost leads to better speed-noise trade-offs.
A recent work proposed a simulator (SGNSim, Stochastic Gene Networks Simulator), that can model GRNs where transcription and translation are modeled as multiple time delayed events and its dynamics is driven by a stochastic simulation algorithm (SSA) able to deal with multiple time delayed events.
The time delays can be drawn from several distributions and the reaction rates from complex
functions or from physical parameters. SGNSim can generate ensembles of GRNs within a set of user-defined parameters, such as topology. It can also be used to model specific GRNs and systems of chemical reactions. Genetic perturbations such as gene deletions, gene over-expression, insertions, frame shift mutations can also be modeled as well.
The GRN is created from a graph with the desired topology, imposing in-degree and out-degree distributions. Gene promoter activities are affected by other genes expression products that act as inputs, in the form of monomers or combined into multimers and set as direct or indirect. Next, each direct input is assigned to an operator site and different transcription factors can be allowed, or not, to compete for the same operator site, while indirect inputs are given a target. Finally, a function is assigned to each gene, defining the gene's response to a combination of transcription factors (promoter state). The transfer functions (that is, how genes respond to a combination of inputs) can be assigned to each combination of promoter states as desired.
In other recent work, multiscale models of gene regulatory networks have been developed that focus on synthetic biology applications. Simulations have been used that model all biomolecular interactions in transcription, translation, regulation, and induction of gene regulatory networks, guiding the design of synthetic systems. | 1 | Gene expression + Signal Transduction |
Adhesion GPCRs appear capable to follow standard GPCR signaling modes and signal through Gαs, Gαq, Gαi, and Gα12/13. As of today, many of the adhesion GPCRs are still orphan receptors and their signalling pathways have not been identified. Research groups are working to elucidate the downstream signaling molecules utilizing several methods, including chemical screens and analysis of second messenger levels in over-expressed cells. Adding drugs in vitro, while the cells are over-expressing an adhesion GPCR, has allowed the identification of the molecules activating the GPCR and the second messengers being utilized.
GPR133 signals through Gαs to activate adenylyl cyclase. It has been shown that overexpressing GPCRs in vitro can result in receptor activation in the absence of a ligand or agonist. By over expressing GPR133 in vitro, an elevation in reporter genes and cAMP was observed. Signaling of the overexpressed GPR133 did not require an N-terminus or GPS cleavage. Missense mutations in the 7TM region resulted in loss of signalling.
The latrophilin homolog LPHN1 was shown in C. elegans to require a GPS for signaling, but cleavage at the GPS site was not necessary. Furthermore, having a shortened 7 transmembrane domain, but with an intact GPS domain, resulted in a loss of signaling. This suggests that having both the GPS and 7 transmembrane domain intact is involved in signaling and that the GPS site could act as or be a necessary part of an endogenous ligand.
GPR56 has been shown to be cleaved at the GPS site and then remain associated with the 7TM domain. In a study where the N-terminus was removed up to N342 (the start of the GPS), the receptor became constitutively active and an up regulation of Gα12/13 was seen. When receptors are active, they are ubiquitinated and GPR56 lacking an N-terminus was highly ubiquitinated. | 1 | Gene expression + Signal Transduction |
Autoinducer-2 (AI-2), a furanosyl borate diester or tetrahydroxy furan (species dependent), is a member of a family of signaling molecules used in quorum sensing. AI-2 is one of only a few known biomolecules incorporating boron. First identified in the marine bacterium Vibrio harveyi, AI-2 is produced and recognized by many Gram-negative and Gram-positive bacteria. AI-2 arises by the reaction of 4,5-dihydroxy-2,3-pentanedione, which is produced enzymatically, with boric acid and is recognized by the two-component sensor kinase LuxPQ in Vibrionaceae.
AI-2 is actively transported by the Lsr ABC-type transporter into the cell in Enterobacteriaceae and few other bacterial taxa such as Pasteurella, Photorhabdus, Haemophilus, and Bacillus, where it is phosphorylated by LsrK. Then, Phospho-AI-2 binds the transcriptional repressor protein, LsrR, which subsequently is released from the promoter/operator region of the lsr operon – and transcription of the lsr genes is initiated. AI-2 signalling is also regulated by glucose and cAMP/CRP via the lsr operon. In the presence of glucose, low levels of cAMP/CRP result in almost no lsr operon (lsrABCDFG) expression. Without glucose, cAMP-CRP is needed to stimulate the lsr expression, while LsrR represses its expression in the absence of the inducer, phospho-AI-2. As AI-2 accumulates, more AI-2 is taken in via LsrABCD, phosphorylated via LsrK, and the lsr transcription is de-repressed, enabling even more AI-2 uptake.
Doubts have been expressed regarding AI-2s status as a universal signal. Although the luxS gene, which encodes the protein responsible for AI-2 production is widespread, the latter has mainly a primary metabolic role in the recycling of S'-adenosyl--methionine, with AI-2 being a by-product of that process. An unequivocally AI-2 related behavior was found to be restricted primarily to organisms bearing known AI-2 receptor genes. Thus, while it is certainly true that some bacteria respond to AI-2, it is doubtful that it is always being produced for purposes of signaling. | 1 | Gene expression + Signal Transduction |
Fulmer benefited from the immediate post-war climate which was favourable to Research and Development. The UK Government and its agencies continued to spend heavily on R&D. This was despite the fact that Britain was essentially bankrupt and hugely indebted to the United States and Canada. The technological advances which had been made on both sides of the conflict had been impressive: radar, the jet engine, the V-2 rocket and the atomic bomb are just a few examples. The Cold War soon added urgency to further military development and there was enthusiasm for developing peaceful uses of atomic energy. | 0 | Metallurgy |
The recrystallization temperature is temperature at which recrystallization can occur for a given material and processing conditions. This is not a set temperature and is dependent upon factors including the following:
* Increasing annealing time decreases recrystallization temperature
* Alloys have higher recrystallization temperatures than pure metals
* Increasing amount of cold work decreases recrystallization temperature
* Smaller cold-worked grain sizes decrease the recrystallization temperature | 0 | Metallurgy |
The following process models are commonly applied to geometallurgy:
* The Bond equation
* The SPI calibration equation, CEET
* FLEET*
* SMC model
* Aminpro-Grind, Aminpro-Flot models | 0 | Metallurgy |
GLD-2, as a poly(A) polymerase (PAP) acts incorporating ATP at the 3' end of mRNAs in a template-independent manner. | 1 | Gene expression + Signal Transduction |
While FeAl is a B2 alloy, the observed yield strength anomaly in FeAl is due to another mechanism. If cross-slip were the mechanism, then the yield strength anomaly would be rate dependent, as expected for a thermally activated process. Instead, yield strength anomaly is state dependent, which is a property that is dependent on the state of the material. As a result, vacancy activated strengthening is the most widely-accepted mechanism. The vacancy formation energy is low for FeAl, allowing for an unusually high concentration of vacancies in FeAl at high temperatures (2.5% at 1000C for Fe-50Al). The vacancy formed in either aluminum-rich FeAl or through heating is an aluminum vacancy.
At low temperatures around 300K, the yield strength either decreases or does not change with temperature. At moderate temperatures (0.35-0.45 T), yield strength has been observed to increase with an increased vacancy concentration, providing further evidence for a vacancy driven strengthening mechanism. The increase in yield strength from increased vacancy concentration is believed to be the result of dislocations being pinned by vacancies on the slip plane, causing the dislocations to bow. Then, above the peak stress temperature, vacancies can migrate as vacancy migration is easier with elevated temperatures. At those temperatures, vacancies no longer hinder dislocation motion but rather aid climb. In the vacancy strengthening model, the increased strength below the peak stress temperature is approximated as proportional to the vacancy concentration to the one-half with the vacancy concentration estimated using Maxwell-Boltzmann statistics. Thus, the strength can be estimated as , with being the vacancy formation energy and T being the absolute temperature. Above the peak stress temperature, a diffusion-assisted deformation mechanism can be used to describe strength since vacancies are now mobile and assist dislocation motion. Above the peak, the yield strength is strain rate dependent and thus, the peak yield strength is rate dependent. As a result, the peak stress temperature increases with an increased strain rate. Note, this is different than the yield strength anomaly, which is the yield strength below the peak, being rate dependent. The peak yield strength is also dependent on percent aluminum in the FeAl alloy. As the percent aluminum increases, the peak yield strength occurs at lower temperatures.
The yield strength anomaly in FeAl alloys can be hidden if thermal vacancies are not minimized through a slow anneal at a relatively low temperature (~400 °C for ~5 days). Further, the yield strength anomaly is not present in systems that use a very low strain rate as the peak yield strength is strain rate dependent and thus, would occur at temperatures too low to observe the yield strength anomaly. Additionally, since the formation of vacancies requires time, the peak yield strength magnitude is dependent on how long the material is held at the peak stress temperature. Also, the peak yield strength has been found not to be dependent on crystal orientation.
Other mechanisms have been proposed including a cross slip mechanism similar to that for L1, dislocation decomposition into less mobile segments at jogs, dislocation pinning, climb-lock mechanism, and slip vector transition. The slip vector transition from MnAl is not dependent on strain rate and thus, may not follow the vacancy activated strengthening mechanism. Instead, there an order-strengthening mechanism has been proposed. | 0 | Metallurgy |
The École Nationale Supérieure dÉlectrochimie et dÉlectrométallurgie de Grenoble, or ENSEEG, was one of the French Grandes écoles of engineering (engineering schools). It has been created in 1921 under the name Institut d’électrochimie et d’électrométallurgie (IEE) (Institute of Electrochemistry and Electrometallurgy). The name ENSEEG has been chosen in 1948 and ENSEEG has been part of Grenoble Institute of Technology (INPG or GIT) since its creation in 1971. Therefore, the name INPG-ENSEEG has also been commonly used.
ENSEEG delivered a multidisciplinary education in physical chemistry. The ENSEEG engineers are especially competent in materials science, process engineering and electrochemistry. From September 2008, ENSEEG merged with two other Grandes écoles to create Phelma. | 0 | Metallurgy |
In those cases where operational complexities negate the use of a cored mains frequency approach, the standard RF or MF induction heater can be used. This type of unit uses turns of copper tube wound into an electromagnetic coil. There are no cores required, the coil needs to simply surround or be inserted into the part to be heated this makes automating the process straightforward. A further advantage is the ability to not only shrink fit parts but also remove them.
The RF and MF heaters used for induction shrink fitting vary in power from a few kilowatts to many megawatts and depending on the component geometry/diameter/cross section can vary in frequency from 1 kHz to 200 kHz, although the majority of applications use the range between 1 kHz and 100 kHz.
In general terms, it is best to use the lowest practical frequency and a low power density when undertaking shrink fitting as this will generally provide more evenly distributed heat. The exception to this rule is when using heat to remove parts from shafts. In these cases it is often best to shock the component with a rapid heat, this also has the advantage of shortening the time cycle and preventing heat build up in the shaft which can lead to problems with both parts expanding.
In order to select the correct power it is necessary to first calculate the thermal energy required to raise the material to the required temperature in the time allotted. This can be done using the heat content of the material which is normal expressed in kW hours per tonne, the weight of metal to be processed and the time cycle. Once this has been established other factors such as radiated losses from the component, coil losses and other system losses need to be factored in. Traditionally this process involved lengthy and complex calculations in conjunction with a mixture of practical experience and empirical formula. Modern techniques use finite element analysis and other computer-aided manufacturing techniques, however as with all such methods a thorough working knowledge of the induction heating process is still required. When deciding on the correct approach it is often necessary to consider the overall size and thermal conductivity of the work-piece and its expansion characteristics in order to ensure that enough soak time is allowed to create an even heat throughout the component. | 0 | Metallurgy |
In colloid chemistry, flocculation refers to the process by which fine particulates are caused to clump together into a floc. The floc may then float to the top of the liquid (creaming), settle to the bottom of the liquid (sedimentation), or be readily filtered from the liquid. Flocculation behavior of soil colloids is closely
related to freshwater quality. High dispersibility of soil colloids not only directly causes turbidity of the surrounding water but it also induces eutrophication due to the adsorption of nutritional substances in rivers
and lakes and even boats under the sea. | 0 | Metallurgy |
The most common example is selective leaching of zinc from brass alloys containing more than 15% zinc (dezincification) in the presence of oxygen and moisture, e.g. from brass taps in chlorine-containing water. Dezincification has been studied since the Civil War era, and the mechanism by which it occurs was under extensive examination by the 1960s. It is believed that both copper and zinc gradually dissolve out simultaneously, and copper precipitates back from the solution. The material remaining is a copper-rich sponge with poor mechanical properties, and a color changed from yellow to red. Dezincification can be caused by water containing sulfur, carbon dioxide, and oxygen. Stagnant or low velocity waters tend to promote dezincification.
To combat this, arsenic or tin can be added to brass, or gunmetal can be used instead. Dezincification resistant brass (DZR), also known as Brass C352 is an alloy used to make pipe fittings for use with potable water. Plumbing fittings that are resistant to dezincification are appropriately marked, with the letters "CR" (Corrosion Resistant) or DZR (dezincification resistant) in the UK, and the letters "DR" (dezincification resistant) in Australia. | 0 | Metallurgy |
The process of pit nucleation is initiated by the depassivation of the protective oxide layer isolating the metal substrate from the aggressive solution. The depassivation of the protective oxide layer is the less properly understood step in pitting corrosion and its very local and random appearance probably its most enigmatic characteristic. Mechanical or physical damages may locally disrupt the protective layer. Crystalline defects, or impurity inclusions, pre-existing in the base metal material can also serve as nucleation points (especially metal sulfide inclusions). The chemical conditions prevailing in the solution and the nature of the metal, or the alloy composition, are also important factors to take into consideration. Several theories have been elaborated to explain the depassivation process. Anions with weak or strong ligand properties such as chloride () and thiosulfate () respectively can complex the metallic cations (Me) present in the protective oxide layer and so contribute to its local dissolution. Chloride anions could also compete with hydroxide ions () for the sorption onto the oxide layer and start to diffuse into the porosity or the crystal lattice of the oxide layer. Finally, according to the point-defect model elaborated by Digby Macdonald, the migration of crystal defects inside the oxide layer could explain its random localized disappearance. The main interest of the point-defect model is to explain the stochastic character of the pitting corrosion process. | 0 | Metallurgy |
The term intermetallic is used to describe compounds involving two or more metals such as the cyclopentadienyl complex CpNiZn. | 0 | Metallurgy |
Corrosion engineering groups have formed around the world to educate, prevent, slow, and manage corrosion. These include the National Association of Corrosion Engineers (NACE), the European Federation of Corrosion (EFC), The Institute of Corrosion in the UK and the Australasian Corrosion Association. The corrosion engineer's main task is to economically and safely manage the effects of corrosion of materials. | 0 | Metallurgy |
Agricola addresses the book to prominent German aristocrats, the most important of whom were Maurice, Elector of Saxony and his brother Augustus, who were his main patrons. He then describes the works of ancient and contemporary writers on mining and metallurgy, the chief ancient source being Pliny the Elder. Agricola describes several books contemporary to him, the chief being a booklet by Calbus of Freiberg in German. The works of alchemists are then described. Agricola does not reject the idea of alchemy, but notes that alchemical writings are obscure and that we do not read of any of the masters who became rich. He then describes fraudulent alchemists, who deserve the death penalty. Agricola completes his introduction by explaining that, since no other author has described the art of metals completely, he has written this work, setting forth his scheme for twelve books. Finally, he again directly addresses his audience of German princes, explaining the wealth that can be gained from this art. | 0 | Metallurgy |
Transforming growth factor (, or TGF) is used to describe two classes of polypeptide growth factors, TGFα and TGFβ.
The name "Transforming Growth Factor" is somewhat arbitrary, since the two classes of TGFs are not structurally or genetically related to one another, and they act through different receptor mechanisms. Furthermore, they do not always induce cellular transformation, and are not the only growth factors that induce cellular transformation. | 1 | Gene expression + Signal Transduction |
When a ligand activates the G protein-coupled receptor, it induces a conformational change in the receptor that allows the receptor to function as a guanine nucleotide exchange factor (GEF) that exchanges GDP for GTP. The GTP (or GDP) is bound to the G subunit in the traditional view of heterotrimeric GPCR activation. This exchange triggers the dissociation of the G subunit (which is bound to GTP) from the G dimer and the receptor as a whole. However, models which suggest molecular rearrangement, reorganization, and pre-complexing of effector molecules are beginning to be accepted. Both G-GTP and G can then activate different signaling cascades (or second messenger pathways) and effector proteins, while the receptor is able to activate the next G protein. | 1 | Gene expression + Signal Transduction |
As seen in the diagram below, impure titanium, zirconium, hafnium, vanadium, thorium or protactinium is heated in an evacuated vessel with a halogen at 50–250 °C. The patent specifically involved the intermediacy of TiI and ZrI, which were volatilized (leaving impurities as solid). At atmospheric pressure TiI melts at 150 °C and boils at 377 °C, while ZrI melts at 499 °C and boils at 600 °C. The boiling points are lower at reduced pressure. The gaseous metal tetraiodide is decomposed on a white hot tungsten filament (1400 °C). As more metal is deposited the filament conducts better and thus a greater electric current is required to maintain the temperature of the filament. The process can be performed in the span of several hours or several weeks, depending on the particular setup.
Generally, the crystal bar process can be performed using any number of metals using whichever halogen or combination of halogens is most appropriate for that sort of transport mechanism, based on the reactivities involved. The only metals it has been used to purify on an industrial scale are titanium, zirconium and hafnium, and in fact is still in use today on a much smaller scale for special purity needs. | 0 | Metallurgy |
The Hedgehog Signaling pathway is critical in proper tissue patterning and orientation during normal development of most animals. Hedgehog proteins induce cell proliferation in certain cells and differentiations in others. Aberrant activation of the Hedgehog pathway has been implicated in several types of cancers, Basal Cell Carcinoma in particular. This uncontrolled activation of the Hedgehog proteins can be caused by mutations to the signal pathway, which would be ligand independent, or a mutation that causes overexpression of the Hedgehog protein, which would be ligand dependent. In addition, therapy-induced Hedgehog pathway activation has been shown to be necessary for progression of Prostate Cancer tumors after androgen deprivation therapy. This connection between the Hedgehog signaling pathway and human cancers may provide for the possible of therapeutic intervention as treatment for such cancers. The Hedgehog signaling pathway is also involved in normal regulation of stem-cell populations, and required for normal growth and regeneration of damaged organs. This may provide another possible route for tumorigenesis via the Hedgehog pathway. | 1 | Gene expression + Signal Transduction |
As typical for the CMGC kinase group, the catalytic site of MAP kinases has a very loose consensus sequence for substrates. Like all their relatives, they only require the target serine / threonine amino acids to be followed by a small amino acid, preferably proline ("proline-directed kinases"). But as SP/TP sites are extremely common in all proteins, additional substrate-recognition mechanisms have evolved to ensure signaling fidelity. Unlike their closest relatives, the cyclin-dependent kinases (CDKs), where substrates are recognized by the cyclin subunit, MAPKs associate with their substrates via auxiliary binding regions on their kinase domains. The most important such region consists of the hydrophobic docking groove and the negatively charged CD-region. Together they recognize the so-called MAPK docking or D-motifs (also called kinase interaction motif / KIM). D-motifs essentially consist of one or two positively charged amino acids, followed by alternating hydrophobic residues (mostly leucines), typically upstream of the phosphorylation site by 10–50 amino acids. Many of the known MAPK substrates contain such D-motifs that can not only bind to, but also provide specific recognition by certain MAPKs. D-motifs are not restricted to substrates: MAP2 kinases also contain such motifs on their N-termini that are absolutely required for MAP2K-MAPK interaction and MAPK activation. Similarly, both dual-specificity MAP kinase phosphatases and MAP-specific tyrosine phosphatases bind to MAP kinases through the same docking site. D-motifs can even be found in certain MAPK pathway regulators and scaffolds (e.g. in the mammalian JIP proteins).
Other, less well characterised substrate-binding sites also exist. One such site (the DEF site) is formed by the activation loop (when in the active conformation) and the MAP kinase-specific insert below it. This site can accommodate peptides with an FxFP consensus sequence, typically downstream of the phosphorylation site. Note that the latter site can only be found in proteins that need to selectively recognize the active MAP kinases, thus they are almost exclusively found in substrates. Different motifs may cooperate with each other, as in the Elk family of transcription factors, that possess both a D-motif and an FxFP motif. The presence of an FxFP motif in the KSR1 scaffold protein also serves to make it an ERK1/2 substrate, providing a negative feedback mechanism to set the correct strength of ERK1/2 activation. | 1 | Gene expression + Signal Transduction |
The polypyrimidine tract is a region of pre-messenger RNA (mRNA) that promotes the assembly of the spliceosome, the protein complex specialized for carrying out RNA splicing during the process of post-transcriptional modification. The region is rich with pyrimidine nucleotides, especially uracil, and is usually 15–20 base pairs long, located about 5–40 base pairs before the 3' end of the intron to be spliced.
A number of protein factors bind to or associate with the polypyrimidine tract, including the spliceosome component U2AF and the polypyrimidine tract-binding protein (PTB), which plays a regulatory role in alternative splicing. PTB's primary function is in exon silencing, by which a particular exon region normally spliced into the mature mRNA is instead left out, resulting in the expression of an isoform of the protein for which the mRNA codes. Because PTB is ubiquitously expressed in many higher eukaryotes, it is thought to suppress the inclusion of "weak" exons with poorly defined splice sites. However, PTB binding is not sufficient to suppress "robust" exons.
The suppression or selection of exons is critical to the proper expression of tissue-specific isoforms. For example, smooth muscle and skeletal muscle express alternate isoforms distinguished by mutually exclusive exon selection in alpha-tropomyosin. | 1 | Gene expression + Signal Transduction |
Green rust compounds were identified in green corrosion crusts that form on iron and steel surfaces, in alternating aerobic and anaerobic conditions, by water containing anions such as chloride, sulfate, carbonate, or bicarbonate. They are believed to be intermediates in the oxidative corrosion of iron to form iron(III) oxyhydroxides (ordinary brown rust). The green rust may be formed either directly from metallic iron or from iron(II) hydroxide () . | 0 | Metallurgy |
Ribozymes, antisense oligonucleotides, and more recently RNAi have been used to target mRNA molecules involved in asthma. These experiments have suggested that siRNA may be used to combat other respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis. COPD is characterized by goblet cell hyperplasia and mucus hypersecretion. Mucus secretion was found to be reduced when the transforming growth factor (TGF)-α was targeted by siRNA in NCI-H292 human airway epithelial cells. In addition to mucus hypersecretion, chronic inflammation and damaged lung tissue are characteristic of COPD and asthma. The transforming growth factor TGF-β is thought to play a role in these manifestations. As a result, when interferon (IFN)-γ was used to knock down TGF-β, fibrosis of the lungs, caused by damage and scarring to lung tissue, was improved. | 1 | Gene expression + Signal Transduction |
Initial scientific discoveries towards modern-day laser peening began in the early 1960s as pulsed-laser technology began to proliferate around the world. In an early investigation of the laser interaction with materials by Gurgen Askaryan and E.M. Moroz, they documented pressure measurements on a targeted surface using a pulsed laser. The pressures observed were much larger than could be created by the force of the laser beam alone. Research into the phenomenon indicated the high-pressure resulted from a momentum impulse generated by material vaporization at the target surface when rapidly heated by the laser pulse. Throughout the 1960s, a number of investigators further defined and modeled the laser beam pulse interaction with materials and the subsequent generation of stress waves. These, and other studies, observed that stress waves in the material were generated from the rapidly expanding plasma created when the pulsed laser beam struck the target. Subsequently, this led to interest in achieving higher pressures to increase the stress wave intensity. To generate higher pressures it was necessary to increase the power density and focus the laser beam (concentrate the energy), requiring that the laser beam-material interaction occur in a vacuum chamber to avoid dielectric breakdown within the beam in air. These constraints limited study of high-intensity pulsed laser–material interactions to a select group of researchers with high-energy pulsed lasers.
In the late 1960s a major breakthrough occurred when N.C. Anderholm discovered that much higher plasma pressures could be achieved by confining the expanding plasma against the target surface. Anderholm confined the plasma by placing a quartz overlay, transparent to the laser beam, firmly against the target surface. With the overlay in place, the laser beam passed through the quartz before interacting with the target surface. The rapidly expanding plasma was now confined within the interface between the quartz overlay and the target surface. This method of confining the plasma greatly increased the resulting pressure, generating pressure peaks of , over an order of magnitude greater than unconfined plasma pressure measurements. The significance of Anderholm's discovery to laser peening was the demonstration that pulsed laser–material interactions to develop high-pressure stress waves could be performed in air, not constrained to a vacuum chamber. | 0 | Metallurgy |
It was only after this that economically viable means of converting pig iron to bar iron began to be devised. A process known as potting and stamping was devised in the 1760s and improved in the 1770s, and seems to have been widely adopted in the West Midlands from about 1785. However, this was largely replaced by Henry Cort's puddling process, patented in 1784, but probably only made to work with grey pig iron in about 1790. These processes permitted the great expansion in the production of iron that constitutes the Industrial Revolution for the iron industry.
In the early 19th century, Hall discovered that the addition of iron oxide to the charge of the puddling furnace caused a violent reaction, in which the pig iron was decarburised, this became known as wet puddling. It was also found possible to produce steel by stopping the puddling process before decarburisation was complete. | 0 | Metallurgy |
MP Materials is 51.8%-owned by US hedge funds JHL Capital Group (and its CEO James Litinsky) and QVT Financial LP, while Shenghe Resources Holding Co. Ltd., a partially state-owned enterprise of the Government of China, holds an 8.0% stake. Apart from institutions, the public owns 18%. | 0 | Metallurgy |
The Petrochemical industry typically encounters aggressive corrosive media. These include sulfides and high temperatures. Corrosion control and solutions are thus necessary for the world economy. Scale formation in injection water presents its own problems with regard to corrosion and thus for the corrosion engineer. | 0 | Metallurgy |
Sulfur concrete was developed and promoted as a building material to get rid of large amounts of stored sulfur produced by hydrodesulfurization of gas and oil (Claus process). As of 2011, sulfur concrete has only been used in small quantities when fast curing or acid resistance is necessary.The material has been suggested by researchers as a potential building material on Mars, where water and limestone are not easily available, but sulfur is. | 0 | Metallurgy |
Tin extraction and use can be dated to the beginning of the Bronze Age around 3000 BC, during which copper objects formed from polymetallic ores had different physical properties. The earliest bronze objects had tin or arsenic content of less than 2% and are therefore believed to be the result of unintentional alloying due to trace metal content in copper ores such as tennantite, which contains arsenic. The addition of a second metal to copper increases its hardness, lowers the melting temperature, and improves the casting process by producing a more fluid melt that cools to a denser, less spongy metal. This was an important innovation that allowed for the much more complex shapes cast in closed molds of the Bronze Age. Arsenical bronze objects appear first in the Middle East where arsenic is commonly found in association with copper ore, but the health risks were quickly realized and the quest for sources of the much less hazardous tin ores began early in the Bronze Age. This created the demand for rare tin metal and formed a trade network that linked the distant sources of tin to the markets of Bronze Age cultures.
Cassiterite (SnO), oxidized tin, most likely was the original source of tin in ancient times. Other forms of tin ores are less abundant sulfides such as stannite that require a more involved smelting process. Cassiterite often accumulates in alluvial channels as placer deposits due to the fact that it is harder, heavier, and more chemically resistant than the granite in which it typically forms. These deposits can be easily seen in river banks, because cassiterite is usually black or purple or otherwise dark, a feature exploited by early Bronze Age prospectors. It is likely that the earliest deposits were alluvial and perhaps exploited by the same methods used for panning gold in placer deposits. | 0 | Metallurgy |
In the US, where the Midrex process was first developed, direct reduction was seen in the 1960s as a way of breathing new life into electric steelmaking. The techno-economic model of the mini-mill, based on flexibility and reduced plant size, was threatened by a shortage of scrap metal, and a consequent rise in its price. With the same shortage affecting metallurgical coke, a return to the blast furnace route did not seem an attractive solution.
Direct reduction is theoretically well-suited to the use of ores that are less compatible with blast furnaces (such as fine ores that clog furnaces), which are less expensive. It also requires less capital, making it a viable alternative to the two tried-and-tested methods of electric furnaces and blast furnaces.
The comparative table shows that the diversity of processes is also justified by the need for quality materials. The coking plant that feeds a battery of blast furnaces is just as expensive as the blast furnace and requires a specific quality of coal. Conversely, many direct-reduction processes are disadvantaged by the costly transformation of ore into pellets: these cost on average 70% more than raw ore. Finally, gas requirements can significantly increase investment costs: gas produced by a COREX is remarkably well-suited to feeding a Midrex unit, but the attraction of the low investment then fades. | 0 | Metallurgy |
PT is released from B. pertussis in an inactive form. Following PT binding to a cell membrane receptor, it is taken up in an endosome, after which it undergoes retrograde transport to the trans-Golgi network and endoplasmic reticulum. At some point during this transport, the A subunit (or protomer) becomes activated, perhaps through the action of glutathione and ATP. PT catalyzes the ADP-ribosylation of the α subunits of the heterotrimeric G protein. This prevents the G proteins from interacting with G protein-coupled receptors on the cell membrane, thus interfering with intracellular communication. The Gi subunits remain locked in their GDP-bound, inactive state, thus unable to inhibit adenylate cyclase activity, leading to increased cellular concentrations of cAMP.
Increased intracellular cAMP affects normal biological signaling. The toxin causes several systemic effects, among which is an increased release of insulin, causing hypoglycemia. Whether the effects of pertussis toxin are responsible for the paroxysmal cough remains unknown.
As a result of this unique mechanism, PT has also become widely used as a biochemical tool to ADP-ribosylate GTP-binding proteins in the study of signal transduction. It has also become an essential component of new acellular vaccines. | 1 | Gene expression + Signal Transduction |
Copper and copper-based metals continued to be the major metal in use during the first part of the Iron Age (end of 2nd–beginning of 1st millennium BCE). Bronze scrap re-melting continued (mainly v-shaped clay crucibles, slags, clay tuyères) and structures of open campfires full of metal production remains were found in several sites in Israel associated mainly with the Philistines and the Sea People settlements on the northern Sharon coast between modern Tel Aviv and Haifa, e.g., Tel Qasile, Tel Gerisa, Tel Dor, and Tel Dan, in northern Israel. Only later in the Iron Age did metallic iron start to play a major role as a base metal for tools and weapons.
XRF analyses of metals, metallurgical remains, and FTIR + XRF analyses of archaeological sediments
from the open industrial area G in Tel Dor enabled the identification of the exact locations of metal working during the end of the Late Bronze Age and the Iron Age. It was also possible to partially reconstruct the pyrotechnological events that probably involved re-melting bronze in an open fireplace. Even after thousands of years the ash, charcoal, calcite, and burnt ground in the immediate vicinity of the metal work area retained significantly higher values of copper (circa 0.05 wt% Cu) than the surrounding archaeological layers.
During Iron Age II and III and the Persian Period (the first half of the first millennium BCE), copper-based objects continued to be present beside growing numbers of iron products. Silver hoards containing small tongueshaped bar chunks or scrapped jewellery became more and more common in the archaeological context in Israel as well as all over the Mediterranean. A similar phenomenon was evident during the Persian Period on the coast of Israel, where copper and copper-based objects were found in relatively large quantities and with parallels in other sites all around the Mediterranean Sea. What could be defined as a basic Phoenician metal “kit” is composed mainly of the “Irano–Scythian” shape of three winged and socketed arrowheads made mainly of tin bronze, sometimes with arsenic and/or lead and left as-cast, and “hand”-like decorated fibulae made of good quality (7 wt%–12 wt% Sn) tin bronze and lead (up to 17 wt% Pb). They underwent mechanical treatment after casting and an extensive final cold working in the area where the needle spring was fastened into the fibulae body. Long unalloyed copper nails that were found in coastal sites as well as part of the structure of ships were found in the shipwreck from Ma’agan Mikhael. | 0 | Metallurgy |
The three TET genes are expressed as different isoforms, including at least two isoforms of TET1, three of TET2 and three of TET3. Different isoforms of the TET genes are expressed in different cells and tissues. The full-length canonical TET1 isoform appears virtually restricted to early embryos, embryonic stem cells and primordial germ cells (PGCs). The dominant TET1 isoform in most somatic tissues, at least in the mouse, arises from alternative promoter usage which gives rise to a short transcript and a truncated protein designated TET1s. The three isoforms of TET2 arise from different promoters. They are expressed and active in embryogenesis and differentiation of hematopoietic cells. The isoforms of TET3 are the full length form TET3FL, a short form splice variant TET3s, and a form that occurs in oocytes designated TET3o. TET3o is created by alternative promoter use and contains an additional first N-terminal exon coding for 11 amino acids. TET3o only occurs in oocytes and the one cell stage of the zygote and is not expressed in embryonic stem cells or in any other cell type or adult mouse tissue tested. Whereas TET1 expression can barely be detected in oocytes and zygotes, and TET2 is only moderately expressed, the TET3 variant TET3o shows extremely high levels of expression in oocytes and zygotes, but is nearly absent at the 2-cell stage. It appears that TET3o, high in oocytes and zygotes at the one cell stage, is the major TET enzyme utilized when almost 100% rapid demethylation occurs in the paternal genome just after fertilization and before DNA replication begins (see DNA demethylation). | 1 | Gene expression + Signal Transduction |
(AD 900–1500)
Utilitarian and ceremonial objects; objects of personal adornment
#Coatlán, Oaxaca
#Coixtlahuaca, Oaxaca
#Ejutla, Oaxaca
#Guiengola, Oaxaca
#Huajuapan, Oaxaca
#Huitzo, Oaxaca
#Juquila, Oaxaca
#Mitla, Oaxaca
#Monte Albán Oaxaca
#Sola de Vega, Oaxaca
#Tehuantepec, Oaxaca
#Teotitlán del Camino, Oaxaca
#Teotitlán del Valle, Oaxaca
#Tlacolula, Oaxaca
#Tlaxiaco, Oaxaca
#Tututepec, Oaxaca
#Xaaga, Oaxaca
#Yanhuitlán, Oaxaca
#Zachila, Oaxaca | 0 | Metallurgy |
Imiquimod (cardinally used in dermatology) is a TLR7 agonist, and its successor resiquimod, is a TLR7 and TLR8 agonist. Recently, resiquimod has been explored as an agent for cancer immunotherapy, acting through stimulation of tumor-associated macrophages.
Several TLR ligands are in clinical development or being tested in animal models as vaccine adjuvants, with the first clinical use in humans in a recombinant herpes zoster vaccine in 2017, which contains a monophosphoryl lipid A component.
TLR7 messenger RNA expression levels in dairy animals in a natural outbreak of foot-and-mouth disease have been reported.
TLR4 has been shown to be important for the long-term side-effects of opioids. Its activation leads to downstream release of inflammatory modulators including TNF-α and IL-1β, and constant low-level release of these modulators is thought to reduce the efficacy of opioid drug treatment with time, and is involved in opioid tolerance, hyperalgesia and allodynia. Morphine induced TLR4 activation attenuates pain suppression by opioids and enhances the development of opioid tolerance and addiction, drug abuse, and other negative side effects such as respiratory depression and hyperalgesia. Drugs that block the action of TNF-α or IL-1β have been shown to increase the analgesic effects of opioids and reduce the development of tolerance and other side-effects, and this has also been demonstrated with drugs that block TLR4 itself.
The "unnatural" enantiomers of opioid drugs such as (+)-morphine and (+)-naloxone lack affinity for opioid receptors, still produce the same activity at TLR4 as their "normal" enantiomers. So, "unnatural" entianomers of opioids such as (+)-naloxone, can be used to block the TLR4 activity of opioid analgesic drugs without having any affinity for μ-opioid receptor | 1 | Gene expression + Signal Transduction |
Non-pathogenic species of the gram-positive Corynebacterium are used for the commercial production of various amino acids. The C. glutamicum species is widely used for producing glutamate and lysine, components of human food, animal feed and pharmaceutical products.
Expression of functionally active human epidermal growth factor has been done in C. glutamicum, thus demonstrating a potential for industrial-scale production of human proteins. Expressed proteins can be targeted for secretion through either the general, secretory pathway (Sec) or the twin-arginine translocation pathway (Tat).
Unlike gram-negative bacteria, the gram-positive Corynebacterium lack lipopolysaccharides that function as antigenic endotoxins in humans. | 1 | Gene expression + Signal Transduction |
This method of deoxidization involves adding specific metals into the steel. These metals will react with the unwanted oxygen, forming a strong oxide that, compared to pure oxygen, will reduce the steel's strength and qualities by a lesser amount.
The chemical equation for deoxidization is represented by:
where n and m are coefficients, D is the deoxidizing agent, and O is oxygen.
Thus, the chemical equilibrium equation involved is:
where a is the activity, or concentration, of the oxide in the steel,
a is the activity of the deoxidizing agent,
and a is the activity of the oxygen.
An increase in the equilibrium constant K will cause an increase in a, and thus more of the oxide product.
K can be manipulated by the steel temperature via the following equation:
where A and B are parameters specific to different deoxidizers and T is the temperature in K°. Below are the values for certain deoxidizers at a temperature of 1873 K°.
Below is a list of commonly used metallic deoxidizers:
* Ferrosilicon, ferromanganese, calcium silicide - used in steelmaking in production of carbon steels, stainless steels, and other ferrous alloys
* Manganese - used in steelmaking
* Silicon carbide, calcium carbide - used as ladle deoxidizer in steel production
* Aluminum dross - also a ladle deoxidizer, used in secondary steelmaking
* Calcium - used as a deoxidizer, desulfurizer, or decarbonizer for ferrous and non-ferrous alloys
* Titanium - used as a deoxidizer for steels
* Phosphorus, copper(I) phosphide - used in production of oxygen-free copper
* Calcium hexaboride - used in production of oxygen-free copper, yields higher conductivity copper than phosphorus-deoxidized
* Yttrium - used to deoxidize vanadium and other non-ferrous metals
* Zirconium
* Magnesium
* Carbon
* Tungsten | 0 | Metallurgy |
Chromatin relaxation is one of the earliest cellular responses to DNA damage. Several experiments have been performed on the recruitment kinetics of proteins involved in the response to DNA damage. The relaxation appears to be initiated by PARP1, whose accumulation at DNA damage is half complete by 1.6 seconds after DNA damage occurs. This is quickly followed by accumulation of chromatin remodeler Alc1, which has an ADP-ribose–binding domain, allowing it to be quickly attracted to the product of PARP1. The maximum recruitment of Alc1 occurs within 10 seconds of DNA damage. About half of the maximum chromatin relaxation, presumably due to action of Alc1, occurs by 10 seconds. PARP1 action at the site of a double-strand break allows recruitment of the two DNA repair enzymes MRE11 and NBS1. Half maximum recruitment of these two DNA repair enzymes takes 13 seconds for MRE11 and 28 seconds for NBS1.
Another process of chromatin relaxation, after formation of a DNA double-strand break, employs γH2AX, the phosphorylated form of the H2AX protein. The histone variant H2AX constitutes about 10% of the H2A histones in human chromatin. γH2AX (phosphorylated on serine 139 of H2AX) was detected at 20 seconds after irradiation of cells (with DNA double-strand break formation), and half maximum accumulation of γH2AX occurred in one minute. The extent of chromatin with phosphorylated γH2AX is about two million base pairs at the site of a DNA double-strand break.
γH2AX does not, by itself, cause chromatin decondensation, but within seconds of irradiation the protein "Mediator of the DNA damage checkpoint 1" (MDC1) specifically attaches to γH2AX. This is accompanied by simultaneous accumulation of RNF8 protein and the DNA repair protein NBS1 which bind to MDC1 as MDC1 attaches to γH2AX. RNF8 mediates extensive chromatin decondensation, through its subsequent interaction with CHD4 protein, a component of the nucleosome remodeling and deacetylase complex NuRD. CHD4 accumulation at the site of the double-strand break is rapid, with half-maximum accumulation occurring by 40 seconds after irradiation.
The fast initial chromatin relaxation upon DNA damage (with rapid initiation of DNA repair) is followed by a slow recondensation, with chromatin recovering a compaction state close to its pre-damage level in ~ 20 min. | 1 | Gene expression + Signal Transduction |
Fulmer Research Institute was founded in 1945 by Col W C (Dev) Devereux and incorporated in 1946. He had been a pioneer in the use of light metal alloys in aero engines and, in the Second World War, he had an important role in the UK Ministry of Aircraft Production, organizing the assembly in Britain of American aircraft and reorganizing the repair of aircraft and aero-engines.
After the war, in 1945, he set up a company called Almin Ltd (Associated Light Metal Industries) which brought together a group of companies mostly concerned with the production and processing of aluminium and magnesium alloys. He wanted Almin to have research facilities but he recognised that Almin's R&D needs alone were not sufficient to justify the investment in staff and capital equipment required for properly equipped laboratories. His answer was to establish a contract research organization
along the lines of Battelle Memorial Institute and The Mellon Institute of Industrial Research in the USA.
Thus he founded Fulmer Research Institute as one of the first contract research companies in Britain. Initially it was in temporary accommodation but he soon found a permanent base by purchasing a large Edwardian country house with ten acres of grounds, in the Buckinghamshire village of Stoke Poges. The name Fulmer was the name of the local telephone exchange and that of a nearby village. | 0 | Metallurgy |
The discovery of TOR and mTOR stemmed from independent studies of the natural product rapamycin by Joseph Heitman, Rao Movva, and Michael N. Hall in 1991; by David M. Sabatini, Hediye Erdjument-Bromage, Mary Lui, Paul Tempst, and Solomon H. Snyder in 1994; and by Candace J. Sabers, Mary M. Martin, Gregory J. Brunn, Josie M. Williams, Francis J. Dumont, Gregory Wiederrecht, and Robert T. Abraham in 1995. In 1991, working in yeast, Hall and colleagues identified the TOR1 and TOR2 genes. In 1993, Robert Cafferkey, George Livi, and colleagues, and Jeannette Kunz, Michael N. Hall, and colleagues independently cloned genes that mediate the toxicity of rapamycin in fungi, known as the TOR/DRR genes. However, the molecular target of the FKBP12-rapamycin complex in mammals was not known. In 1994, researchers working in the labs of Stuart L. Schreiber, Solomon H. Snyder and Robert T. Abraham independently discovered a protein that directly interacts with FKBP12-rapamycin, which became known as mTOR due to its homology to the yeast TOR/DRR genes.
Rapamycin arrests fungal activity at the G1 phase of the cell cycle. In mammals, it suppresses the immune system by blocking the G1 to S phase transition in T-lymphocytes. Thus, it is used as an immunosuppressant following organ transplantation. Interest in rapamycin was renewed following the discovery of the structurally related immunosuppressive natural product FK506 in 1987. In 1989–90, FK506 and rapamycin were determined to inhibit T-cell receptor (TCR) and IL-2 receptor signaling pathways, respectively. The two natural products were used to discover the FK506- and rapamycin-binding proteins, including FKBP12, and to provide evidence that FKBP12–FK506 and FKBP12–rapamycin might act through gain-of-function mechanisms that target distinct cellular functions. These investigations included key studies by Francis Dumont and Nolan Sigal at Merck contributing to show that FK506 and rapamycin behave as reciprocal antagonists. These studies implicated FKBP12 as a possible target of rapamycin, but suggested that the complex might interact with another element of the mechanistic cascade.
In 1991, calcineurin was identified as the target of FKBP12-FK506. That of FKBP12-rapamycin remained mysterious until genetic and molecular studies in yeast established FKBP12 as the target of rapamycin, and implicated TOR1 and TOR2 as the targets of FKBP12-rapamycin in 1991 and 1993, followed by studies in 1994 when several groups, working independently, discovered the mTOR kinase as its direct target in mammalian tissues. Sequence analysis of mTOR revealed it to be the direct ortholog of proteins encoded by the yeast target of rapamycin 1 and 2 (TOR1 and TOR2) genes, which Joseph Heitman, Rao Movva, and Michael N. Hall had identified in August 1991 and May 1993. Independently, George Livi and colleagues later reported the same genes, which they called dominant rapamycin resistance 1 and 2 (DRR1 and DRR2), in studies published in October 1993.
The protein, now called mTOR, was originally named FRAP by Stuart L. Schreiber and RAFT1 by David M. Sabatini; FRAP1 was used as its official gene symbol in humans. Because of these different names, mTOR, which had been first used by Robert T. Abraham, was increasingly adopted by the community of scientists working on the mTOR pathway to refer to the protein and in homage to the original discovery of the TOR protein in yeast that was named TOR, the Target of Rapamycin, by Joe Heitman, Rao Movva, and Mike Hall. TOR was originally discovered at the Biozentrum and Sandoz Pharmaceuticals in 1991 in Basel, Switzerland, and the name TOR pays further homage to this discovery, as TOR means doorway or gate in German, and the city of Basel was once ringed by a wall punctuated with gates into the city, including the iconic Spalentor. "mTOR" initially meant "mammalian target of rapamycin", but the meaning of the "m" was later changed to "mechanistic". Similarly, with subsequent discoveries the zebra fish TOR was named zTOR, the Arabidopsis thaliana TOR was named AtTOR, and the Drosophila TOR was named dTOR. In 2009 the FRAP1 gene name was officially changed by the HUGO Gene Nomenclature Committee (HGNC) to mTOR, which stands for mechanistic target of rapamycin.
The discovery of TOR and the subsequent identification of mTOR opened the door to the molecular and physiological study of what is now called the mTOR pathway and had a catalytic effect on the growth of the field of chemical biology, where small molecules are used as probes of biology. | 1 | Gene expression + Signal Transduction |
As mentioned, Gram-negative bacteria primarily use acylated homoserine lactones (AHLs) as autoinducer molecules. The minimum quorum sensing circuit in Gram-negative bacteria consists of a protein that synthesizes an AHL and a second, different protein that detects it and causes a change in gene expression. First identified in V. fischeri, these two such proteins are LuxI and LuxR, respectively. Other Gram-negative bacteria use LuxI-like and LuxR-like proteins (homologs), suggesting a high degree of evolutionary conservation. However, among Gram-negatives, the LuxI/LuxI-type circuit has been modified in different species. Described in more detail below, these modifications reflect bacterial adaptations to grow and respond to particular niche environments. | 1 | Gene expression + Signal Transduction |
Cancer-based research into co-receptors includes the investigation of growth factor activated co-receptors, such as Transforming Growth Factor (TGF-β) co-receptors. Expression of the co-receptor endoglin, which is expressed on the surface of tumor cells, is correlated with cell plasticity and the development of tumors.
Another co-receptor of TGF-β is CD8. Although the exact mechanism is still unknown, CD8 co-receptors have been shown to enhance T-cell activation and TGF-β-mediated immune suppression.
TGF-β has been shown to influence the plasticity of cells through integrin and focal adhesion kinase. The co-receptors of tumor cells and their interaction with T-cells provide important considerations for tumor immunotherapy.
Recent research into co-receptors for p75, such as the sortilin co-receptor, has implicated sortilin in connection to neurotrophins, a type of nerve growth factor.
The p75 receptor and co-receptors have been found to influence the aggressiveness of tumors, specifically via the ability of neurotrophins to rescue cells from certain forms of cell death.
Sortilin, the p75 co-receptor, has been found in natural killer cells, but with only low levels of neurotrophin receptor. The sortilin co-receptor is believed to work with a neurotrophin homologue that can also cause neurotrophin to alter the immune response. | 1 | Gene expression + Signal Transduction |
A number of adhesion GPCRs may have important roles within the immune system. In particular, members the EGF-TM7 subfamily which possess N-terminal EGF-like domains are predominantly restricted to leukocytes suggesting a putative role in immune function. The human EGF‑TM7 family is composed of CD97, EMR1 (F4/80 receptor orthologue) EMR2, EMR3 and EMR4 (a probable pseudogene in humans). The human-restricted EMR2 receptor, is expressed by myeloid cells including monocytes, dendritic cells and neutrophils has been shown to be involved in the activation and migration of human neutrophils and upregulated in patients with systemic inflammatory response syndrome (SIRS). Details of EMR1, CD97 needed. The adhesion‑GPCR brain angiogenesis inhibitor 1 (BAI1) acts as a phosphatidylserine receptor playing a potential role in the binding and clearance of apoptotic cells, and the phagocytosis of Gram-negative bacteria. GPR56 has been shown to a marker for inflammatory NK cell subsets and to be expressed by cytotoxic lymphocytes. | 1 | Gene expression + Signal Transduction |
In oxidizing environment, green rust generally turns into oxyhydroxides, namely α- (goethite) and γ- (lepidocrocite).
Oxidation of the carbonate variety can be retarded by wetting the material with hydroxyl-containing compounds such as glycerol or glucose, even though they do not penetrate the structure. Some variety of green rust is stabilized also by an atmosphere with high partial pressure.
Sulfate green rust has been shown to reduce nitrate and nitrite in solution to ammonium , with concurrent oxidation of to . Depending on the cations in the solution, the nitrate anions replaced the sulfate in the intercalation layer, before the reduction. It was conjectured that green rust may be formed in the reducing alkaline conditions below the surface of marine sediments and may be connected to the disappearance of oxidized species like nitrate in that environment.
Suspensions of carbonate green rust and orange γ- in water will react over a few days produce a black precipitate of magnetite . | 0 | Metallurgy |
As mentioned above, MAPKs typically form multi-tiered pathways, receiving input several levels above the actual MAP kinase. In contrast to the relatively simple, phosphorylation-dependent activation mechanism of MAPKs and MAP2Ks, MAP3Ks have stunningly complex regulation. Many of the better-known MAP3Ks, such as c-Raf, MEKK4 or MLK3 require multiple steps for their activation. These are typically allosterically-controlled enzymes, tightly locked into an inactive state by multiple mechanisms. The first step en route to their activation consists of relieving their autoinhibition by a smaller ligand (such as Ras for c-Raf, GADD45 for MEKK4 or Cdc42 for MLK3). This commonly (but not always) happens at the cell membrane, where most of their activators are bound (note that small G-proteins are constitutively membrane-associated due to prenylation). That step is followed by side-to-side homo- and heterodimerisation of their now accessible kinase domains. Recently determined complex structures reveal that the dimers are formed in an orientation that leaves both their substrate-binding regions free. Importantly, this dimerisation event also forces the MAP3 kinase domains to adopt a partially active conformation. Full activity is only achieved once these dimers transphosphorylate each other on their activation loops. The latter step can also be achieved or aided by auxiliary protein kinases (MAP4 kinases, members of the Ste20 family). Once a MAP3 kinase is fully active, it may phosphorylate its substrate MAP2 kinases, which in turn will phosphorylate their MAP kinase substrates. | 1 | Gene expression + Signal Transduction |
Inert anodes are non-carbon based alternatives to traditional anodes used during aluminum reduction. These anodes do not chemically react with the electrolyte, and are therefore not consumed during the reduction process. Because the anode does not contain carbon, carbon dioxide is not produced. Through a review of literature, Haradlsson et al. found that inert anodes reduced the green house gas emissions of the aluminum smelting process by approximately 2 tonnes CO2eq/ tonne Al. | 0 | Metallurgy |
Wood pellets made by compressing sawdust or other ground woody materials are used in a variety of energy and non-energy applications. In the energy sector, wood pellets are often used to replace coal with power plants such as Drax, in England, replacing most of their coal use with woody pellet. As sustainably harvested wood does not lead to a long-term increase in atmospheric carbon dioxide levels, wood fuels are considered to be a low-carbon form of energy. Wood pellets are also used for domestic and commercial heating either in the form of automated boilers or pellet stoves. Compared to other fuels made from wood, pellets have the advantage of higher energy density, simpler handling as it flows similar to grain, and low moisture.
Concerns have been raised about the short-term carbon balance of wood pellet production, particularly if it is driving the harvesting of old or mature harvests that would otherwise not be logged. Areas of concern include the inland rainforests of British Columbia These claims are contested by the pellet and forest industries. | 0 | Metallurgy |
The N-terminal domain of restriction endonuclease EcoRII; the C-terminal domain of restriction endonuclease BfiI possess a similar DNA-binding pseudobarrel protein fold. | 1 | Gene expression + Signal Transduction |
PI3K inhibitors may overcome drug resistance and improve advanced breast cancer (ABC) outcomes. Different PI3K inhibitors exhibit different effect against various PI3K types. Class IA pan-PI3K inhibitors have been more extensively studied than isoform specific inhibitors; Pictilisib is another pan-PI3K inhibitor with greater subunitα-inhibitor activity than buparlisib. Idelalisib is the first PI3K inhibitor approved by the US Food and Drug Administration and is utilized in the treatment of relapsed/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma and follicular lymphoma. Copanlisib is approved for relapsed follicular lymphoma in patients who have received at least two prior systemic therapies. Duvelisib is approved for relapsed/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and relapsed/refractory follicular lymphoma, both indications for patients who have received at least two prior therapies. | 1 | Gene expression + Signal Transduction |
While the sequence that constitutes the 3′-UTR contributes greatly to gene expression, the structural characteristics of the 3′-UTR also play a large role. In general, longer 3′-UTRs correspond to lower expression rates since they often contain more miRNA and protein binding sites that are involved in inhibiting translation. Human transcripts possess 3′-UTRs that are on average twice as long as other mammalian 3′-UTRs. This trend reflects the high level of complexity involved in human gene regulation. In addition to length, the secondary structure of the 3′-untranslated region also has regulatory functions. Protein factors can either aid or disrupt folding of the region into various secondary structures. The most common structure is a stem-loop, which provides a scaffold for RNA binding proteins and non-coding RNAs that influence expression of the transcript. | 1 | Gene expression + Signal Transduction |
Poly(ADP-ribose)polymerases (PARPs) are found mostly in eukaryotes and catalyze the transfer of multiple ADP-ribose molecules to target proteins. As with mono(ADP-ribosyl)ation, the source of ADP-ribose is NAD. PARPs use a catalytic triad of His-Tyr-Glu to facilitate binding of NAD and positioning of the end of the existing poly(ADP-ribose) chain on the target protein; the Glu facilitates catalysis and formation of a (1→2) O'-glycosidic linkage between two ribose molecules.
There are several other enzymes that recognize poly(ADP-ribose) chains, hydrolyse them or form branches; over 800 proteins have been annotated to contain the loosely defined poly(ADP-ribose) binding motif; therefore, in addition to this modification altering target protein conformation and structure, it may also be used as a tag to recruit other proteins or for regulation of the target protein. | 1 | Gene expression + Signal Transduction |
The addition of certain alloying elements, such as manganese and nickel, can stabilize the austenitic structure, facilitating heat-treatment of low-alloy steels. In the extreme case of austenitic stainless steel, much higher alloy content makes this structure stable even at room temperature.
On the other hand, such elements as silicon, molybdenum, and chromium tend to de-stabilize austenite, raising the eutectoid temperature. | 0 | Metallurgy |
Friedrich Deusch used the impressed mark "Deusch 1000 / 1000" on the early items. This mark was punched directly into the silver. Very often one may also find a red three-digit number on the bottom of the porcelain or glass which indicates this early production. Later, it was replaced by a red stamp which shows a coffeepot and the name Deusch. In addition, to these marks, the following marks may also be found: "1000 / 1000 Silber" or "1000 / 1000 Feinsilber". Later items may have the additional mark "Made in Western Germany".
Alfred and Manfred Veyhl used many different marks, stamps and labels (always placed on the bottom of the item). Vehyl's work often shows the "1000/1000 silver" mark included in the body of the design. Some rare items are signed by handwritten monogram (MV for Manfred Veyhl) and the word "Handgemalt" (handpainted).
Friedrich Wilhelm Spahr mostly used marks impressed directly into the silver. The very earliest and rarest of Spahr's marks began with "MSG 1000 10" ("MSG" standing for "Manufaktur Schwäbisch Gmünd"). This mark was followed by "Spahr 1000 10" (sometimes stamped in black letters on a porcelain base), later with "Spahr 1000", and finally with transparent plastic labels on the bottom printed "Spahr Feinsilberauflage 1000 / 1000".
Alvin Corporation, which was later owned by the Gorham Mfg. Co. after 1928, also used special marks. They manufactures pieces of sterling silver flatware, as well as hollowware and special toilet ware.
The La Pierre Manufacturing Company also sued special marks. It was established by Frank H. La Pierre in 1885, and headquartered at 18 East 14th Street, NY. It relocated its offices to Newark, NJ before its incorporation in 1895. Their special marks appear on their silver overlay item such as hollowware and novelty items.
The Rockwell Silver Company established in Meriden, CT around 1905 created a number designs which featured silver overlay, however they were merged with Silver City Glass Company in 1978, so even though they have done extensive work, there are no unique marks associated with the company.
The Gorham Manufacturing Co. which was active from 1848 till 1865 used a lion as their mark. They also used a rams head and the phrase "coin" to mark their items. | 0 | Metallurgy |
The erosive effect of electrical discharges was first noted in 1770 by English physicist Joseph Priestley. | 0 | Metallurgy |