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A volatile corrosion inhibitor (VCI) is a material that protects metals from corrosion. Corrosion inhibitors are chemical compounds that can decrease the corrosion rate of a material, typically a metal or an alloy. NACE International Standard TM0208 defines volatile corrosion inhibitor (VCI) as a chemical substance that acts to reduce corrosion by a combination of volatilization from a VCI material, vapor transport in the atmosphere of an enclosed environment, and condensation onto surface in the space, including absorption, dissolution, and hydrophobic effects on metal surfaces, where the rate of corrosion of metal surfaces is thereby inhibited. They also called vapor-phase inhibitors, vapor-phase corrosion inhibitors, and vapor-transported corrosion inhibitors.
VCIs come in various formulations that are dependent on the type of system they will be used in; for example, films, oils, coatings, cleaners, etc. There are also variety of formulations that provide protection in ferrous, nonferrous, or multi-metal applications. Other variables include the amount of vapor phase compared to contact phase inhibitors. Because they are volatile at ambient temperature, VCI compounds can reach inaccessible crevices in metallic structures.
V.VCI is also called Vacuum VCI meaning they have special properties of performance in vacuum as well as corrosion protection properties. | 0 | Metallurgy |
In 1898, Scientific American published an article called Bessemer Steel and its Effect on the World explaining the significant economic effects of the increased supply in cheap steel. They noted that the expansion of railroads into previously sparsely inhabited regions of the country had led to settlement in those regions, and had made the trade of certain goods profitable, which had previously been too costly to transport.
The Bessemer process revolutionized steel manufacture by decreasing its cost, from £40 per long ton to £6–7 per long ton, along with greatly increasing the scale and speed of production of this vital raw material. The process also decreased the labor requirements for steel-making. Before it was introduced, steel was far too expensive to make bridges or the framework for buildings and thus wrought iron had been used throughout the Industrial Revolution. After the introduction of the Bessemer process, steel and wrought iron became similarly priced, and some users, primarily railroads, turned to steel. Quality problems, such as brittleness caused by nitrogen in the blowing air, prevented Bessemer steel from being used for many structural applications. Open-hearth steel was suitable for structural applications.
Steel greatly improved the productivity of railroads. Steel rails lasted ten times longer than iron rails. Steel rails, which became heavier as prices fell, could carry heavier locomotives, which could pull longer trains. Steel rail cars were longer and were able to increase the freight to car weight from 1:1 to 2:1. | 0 | Metallurgy |
* P. aeruginosa also uses 2-heptyl-3-hydroxy-4-quinolone (PQS) for quorum sensing. This molecule is noteworthy because it does not belong to the homoserine lactone class of autoinducers. PQS is believed to provide an additional regulatory link between the Las and Rhl circuits involved in virulence and infection.
* Agrobacterium tumefaciens is a plant pathogen that induces tumors on susceptible hosts. Infection by A. tumefaciens involves the transfer of an oncogenic plasmid from the bacterium to the host cell nucleus, while quorum sensing controls the conjugal transfer of plasmids between bacteria. Conjugation, on the other hand, requires the HSL autoinducer, N-(3-oxooctanoyl)-homoserine lactone.
* Erwinia carotovora is another plant pathogen that causes soft-rot disease. These bacteria secrete cellulases and pectinases, which are enzymes that degrade plant cell walls. ExpI/ExpR are LuxI/LuxR homologs in E. carotovora believed to control secretion of these enzymes only when a high enough local cell density is achieved. The autoinducer involved in quorum sensing in E. carotovora is N-(3-oxohexanoyl)-L-homoserine lactone. | 1 | Gene expression + Signal Transduction |
CCAAT/enhancer-binding proteins are often involved in growth arrest and differentiation, which has been interpreted to suggest that these proteins harbor tumor suppressive activities. However, CCAAT/enhancer-binding protein over-expression correlates with poor prognosis in glioblastoma and promotes genomic instability in cervical cancer, hinting at an oncogenic role. Importantly, however, C/EBPδ acts as a tumor suppressor in pancreatic ductal adenocarcinoma. This is of particular interest since only few tumor suppressors have been identified in the context of pancreatic cancer. The function of CCAAT/enhancer-binding proteins in cancer is thus clearly context dependent but largely tumor suppressive. | 1 | Gene expression + Signal Transduction |
The density of aluminium granules ranges from 1.0 to 1.8 g/cm and is much higher compared to aluminium powder. | 0 | Metallurgy |
Increases in the intracellular Ca concentrations are often a result of IP activation. When a ligand binds to a G protein-coupled receptor (GPCR) that is coupled to a Gq heterotrimeric G protein, the α-subunit of Gq can bind to and induce activity in the PLC isozyme PLC-β, which results in the cleavage of PIP into IP and DAG.
If a receptor tyrosine kinase (RTK) is involved in activating the pathway, the isozyme PLC-γ has tyrosine residues that can become phosphorylated upon activation of an RTK, and this will activate PLC-γ and allow it to cleave PIP into DAG and IP. This occurs in cells that are capable of responding to growth factors such as insulin, because the growth factors are the ligands responsible for activating the RTK.
IP (also abbreviated Ins(1,4,5)P is a soluble molecule and is capable of diffusing through the cytoplasm to the ER, or the sarcoplasmic reticulum (SR) in the case of muscle cells, once it has been produced by the action of PLC. Once at the ER, IP is able to bind to the Ins(1,4,5)P receptor Ins(1,4,5)PR which is a ligand-gated Ca channel that is found on the surface of the ER. The binding of IP (the ligand in this case) to Ins(1,4,5)PR triggers the opening of the Ca channel, and thus release of Ca into the cytoplasm. In heart muscle cells this increase in Ca activates the ryanodine receptor-operated channel on the SR, results in further increases in Ca through a process known as calcium-induced calcium release. IP may also activate Ca channels on the cell membrane indirectly, by increasing the intracellular Ca concentration. | 1 | Gene expression + Signal Transduction |
Chemokine receptors are G protein-coupled receptors containing 7 transmembrane domains that are found on the surface of leukocytes. Approximately 19 different chemokine receptors have been characterized to date, which are divided into four families depending on the type of chemokine they bind; CXCR that bind CXC chemokines, CCR that bind CC chemokines, CX3CR1 that binds the sole CX3C chemokine (CX3CL1), and XCR1 that binds the two XC chemokines (XCL1 and XCL2). They share many structural features; they are similar in size (with about 350 amino acids), have a short, acidic N-terminal end, seven helical transmembrane domains with three intracellular and three extracellular hydrophilic loops, and an intracellular C-terminus containing serine and threonine residues important for receptor regulation. The first two extracellular loops of chemokine receptors each has a conserved cysteine residue that allow formation of a disulfide bridge between these loops. G proteins are coupled to the C-terminal end of the chemokine receptor to allow intracellular signaling after receptor activation, while the N-terminal domain of the chemokine receptor determines ligand binding specificity. | 1 | Gene expression + Signal Transduction |
Paste tailings is a modification to the conventional methods of disposal of tailings (pond storage). Conventional tailings slurries are composed of a low percent of solids and relatively high water content (normally ranging from 20% to 60% solids for most hard rock mining) and when deposited into the tailings pond the solids and liquids separate. In paste tailings the percent of solids in the tailings slurry is increased through the use of paste thickeners to produce a product where the minimal separation of water and solids occurs and the material is deposited into a storage area as a paste (with a consistency somewhat like toothpaste). Paste tailings has the advantage that more water is recycled in the processing plant and therefore the process is more water efficient than conventional tailings and there is a lower potential for seepage. However the cost of the thickening is generally higher than for conventional tailings and the pumping costs for the paste are also normally higher than for conventional tailings as positive displacement pumps are normally required to transport the tailings from the processing plant to the storage area. Paste tailings are used in several locations around the world including Sunrise Dam in Western Australia and Bulyanhulu Gold Mine in Tanzania. | 0 | Metallurgy |
Almost all proteins that are destined to the secretory pathway have a sequence consisting of 5-30 hydrophobic amino acids on the N-terminus, which is commonly referred to as the signal peptide, signal sequence or leader peptide. Signal peptides form alpha-helical structures. Proteins that contain such signals are destined for either extra-cellular secretion, the plasma membrane, the lumen or membrane of either the (ER), Golgi or endosomes. Certain membrane-bound proteins are targeted to the secretory pathway by their first transmembrane domain, which resembles a typical signal peptide.
In prokaryotes, signal peptides direct the newly synthesized protein to the SecYEG protein-conducting channel, which is present in the plasma membrane. A homologous system exists in eukaryotes, where the signal peptide directs the newly synthesized protein to the Sec61 channel, which shares structural and sequence similarity with SecYEG, but is present in the endoplasmic reticulum. Both the SecYEG and Sec61 channels are commonly referred to as the translocon, and transit through this channel is known as translocation. While secreted proteins are threaded through the channel, transmembrane domains may diffuse across a lateral gate in the translocon to partition into the surrounding membrane. | 1 | Gene expression + Signal Transduction |
Photoreceptor proteins are light-sensitive proteins involved in the sensing and response to light in a variety of organisms. Some examples are rhodopsin in the photoreceptor cells of the vertebrate retina, phytochrome in plants, and bacteriorhodopsin and bacteriophytochromes in some bacteria. They mediate light responses as varied as visual perception, phototropism and phototaxis, as well as responses to light-dark cycles such as circadian rhythm and other photoperiodisms including control of flowering times in plants and mating seasons in animals. | 1 | Gene expression + Signal Transduction |
Laser shocking during the initial development stages was severely limited by the laser technology of the time period. The pulsed laser used by Battelle encompassed one large room and required several minutes of recovery time between laser pulses. To become a viable, economical, and practical industrial process, the laser technology had to mature into equipment with a much smaller footprint and be capable of increased laser pulse frequencies. In the early 1980s, Wagner Castings Company located in Decatur, Illinois became interested in laser peening as a process that could potentially increase the fatigue strength of cast iron to compete with steel, but at a lower cost. Laser peening of various cast irons showed modest fatigue life improvement, and these results along with others, convinced them to fund the design and construction of a pre-prototype pulsed laser in 1986 to demonstrate the industrial viability of the process. This laser was completed and demonstrated in 1987. Although the technology had been under investigation and development for about 15 years, few people in industry had heard of it. So, with the completion of the demonstration laser, a major marketing effort was launched by Wagner Castings and Battelle engineers to introduce laser peening to potential industrial markets.
Also in the mid 1980s, Remy Fabbro of the Ecole Polytechnique was initiating a laser shock peening program in Paris. He and Jean Fournier of the Peugeot Company visited Battelle in 1986 for an extended discussion of laser shock peening with Allan Clauer. The programs initiated by Fabbro and carried forward in the 1990s and early 2000s by Patrice Peyre, Laurent Berthe, and co-workers have made major contributions, both theoretical and experimental, to the understanding and implementation of laser peening. In 1998, they measured using VISAR (Velocimeter Interferometer System for Any Reflector) pressure loadings in water confinement regime as function of wavelength. They demonstrate the detrimental effect of breakdown in water limiting maximum pressure at the surface of material. | 0 | Metallurgy |
Hydrogen lowers tensile ductility in many materials. In ductile materials, like austenitic stainless steels and aluminium alloys, no marked embrittlement may occur, but may exhibit significant lowering in tensile ductility (% elongation or % reduction in area) in tensile tests. | 0 | Metallurgy |
A "lasagna cell" is accidentally produced when salty moist food such as lasagna is stored in a steel baking pan and is covered with aluminium foil. After a few hours the foil develops small holes where it touches the lasagna, and the food surface becomes covered with small spots composed of corroded aluminium. In this example, the salty food (lasagna) is the electrolyte, the aluminium foil is the anode, and the steel pan is the cathode. If the aluminium foil touches the electrolyte only in small areas, the galvanic corrosion is concentrated, and corrosion can occur fairly rapidly. If the aluminium foil was not used with a dissimilar metal container, the reaction was probably a chemical one. It is possible for heavy concentrations of salt, vinegar or some other acidic compounds to cause the foil to disintegrate. The product of either of these reactions is an aluminium salt. It does not harm the food, but any deposit may impart an undesired flavor and color. | 0 | Metallurgy |
*CuMnAl, CuMnIn, CuMnSn
*NiMnAl, NiMnIn, NiMnSn, NiMnSb, NiMnGa
*CoMnAl, CoMnSi, CoMnGa, CoMnGe, CoNiGa, CoMnSn
*PdMnAl, PdMnIn, PdMnSn, PdMnSb
*CoFeSi, CoFeAl
*FeVAl
*MnVGa, CoFeGe
*CoCrFeX(X=Al, Si)
* YbBiPt | 0 | Metallurgy |
Nickel monosilicide is an intermetallic compound formed out of nickel and silicon. Like other nickel silicides, NiSi is of importance in the area of microelectronics. | 0 | Metallurgy |
Main feed into a sinter plant is base mix, which consists of iron ore fines, coke fines and flux (limestone) fines. In addition to base mix, coke fines, flux fines, sinter fines, iron dust (collected from plant de-dusting system & ESP) and plant waste are mixed in proportion (by weight) in a rotary drum, often called mixing and nodulizing drum. Calcined lime is used as binder of the mixed material along with water (all in particular proportion by weight) to form feed-sinter of about 5 to 7 mm in size. This sinter globules are fed to sintering machine and burnt therein to produce blast furnace feed sinter. | 0 | Metallurgy |
Since corepressors participate and regulate a vast range of gene expression, it is not surprising that aberrant corepressor activities can cause diseases.
Acute myeloid leukemia (AML) is a highly lethal blood cancer characterized by uncontrolled myeloid cell growth. Two homologous corepressor genes, BCOR (BCL6 corepressor) and BCORL1, are recurrently mutated in AML patients. BCOR works with multiple transcription factors and is known to play vital regulatory roles in embryonic development. Clinical results detected BCOR somatic mutations in ~4% of an unselected group of AML patients, and ~17% in a subset of patients who lack known AML-causing mutations. Similarly, BCORL1 is a corepressor that regulates cellular processes, and was found to be mutated in ~6% of tested AML patients. These studies point out a strong association between corepressor mutations and AML. Further corepressor research may reveal potential therapeutic targets for AML and other diseases. | 1 | Gene expression + Signal Transduction |
Glass solder is used to join glasses to other glasses, ceramics, metals, semiconductors, mica, and other materials, in a process called glass frit bonding. The glass solder has to flow and wet the soldered surfaces well below the temperature where deformation or degradation of either of the joined materials or nearby structures (e.g., metallization layers on chips or ceramic substrates) occurs. The usual temperature of achieving flowing and wetting is between . | 0 | Metallurgy |
The two-way shape-memory effect is the effect that the material remembers two different shapes: one at low temperatures, and one at the high temperature.
A material that shows a shape-memory effect during both heating and cooling is said to have two-way shape memory. This can also be obtained without the application of an external force (intrinsic two-way effect).
The reason the material behaves so differently in these situations lies in training. Training implies that a shape memory can "learn" to behave in a certain way.
Under normal circumstances, a shape-memory alloy "remembers" its low-temperature shape, but upon heating to recover the high-temperature shape, immediately "forgets" the low-temperature shape. However, it can be "trained" to "remember" to leave some reminders of the deformed low-temperature condition in the high-temperature phases. One way of training the SMA consists in applying a cyclic thermal load under constant stress field. During this process, internal defects are introduced into the microstructure which generates internal permanent stresses that facilitate the orientation of the martensitic crystals. Therefore, while cooling a trained SMA in austenitic phase under no applied stress, the martensite is formed detwinned due to the internal stresses, which leads to the material shape change. And while heating back the SMA into austenite, it recovers its initial shape.
There are several ways of doing this. A shaped, trained object heated beyond a certain point will lose the two-way memory effect. | 0 | Metallurgy |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), and Valine (Val, V). | 1 | Gene expression + Signal Transduction |
The above descriptions ignore the effects of Gβγ–signalling, which can also be important, in particular in the case of activated G-coupled GPCRs. The primary effectors of Gβγ are various ion channels, such as G-protein-regulated inwardly rectifying K channels (GIRKs), P/Q- and N-type voltage-gated Ca channels, as well as some isoforms of AC and PLC, along with some phosphoinositide-3-kinase (PI3K) isoforms. | 1 | Gene expression + Signal Transduction |
With the major breakthrough of commercial application of laser peening on the F101 engine to resolve a major operational problem, laser peening attracted attention around the globe. Researchers in many countries and industries undertook investigations to extend understanding of the laser shock peening process and material property effects. As a result, a large volume of research papers and patents were generated in the United States, France, and Japan. In addition to the work being done in these countries and Spain, laser peening programs were initiated in China, Britain, Germany and several other countries. The continuing growth of the technology and its applications led to the appearance of several commercial laser shock peening providers in the early 2000s.
GE Aviation and LSP Technologies were the first companies performing laser peening commercially, having licensed the technology from Battelle. GE Aviation performed laser peening for its aerospace engine components and LSP Technologies marketed laser shock peening services and equipment to a broader industrial base. In the late 1990s, Metal Improvement Company (MIC is now part of Curtis Wright Surface Technologies) partnered with Lawrence Livermore National Laboratory (LLNL) to develop its own laser peening capabilities. In Japan, Toshiba Corporation expanded the commercial applications of its LPwC system to pressurized water reactors, and in 2002 implemented fiber optic beam delivery to the underwater laser peening head. Toshiba also redesigned the laser and beam delivery into a compact system, enabling the entire system to be inserted into the pressure vessel. This system was ready for commercial use in 2013 MIC developed and adapted laser shock peening for forming the wing shapes on the Boeing 747-8.
The growth of industrial suppliers and commercial proof of laser peening technology lead to many companies adopting laser peening technology to solve and prevent problems. Some of the companies who have adopted laser peening include: GE, Rolls-Royce, Siemens, Boeing, Pratt & Whitney, and others.
In the 1990s and continuing through present day, laser peening developments have targeted decreasing costs and increasing throughput to reach markets outside of high-cost low-volume components. High costs in the laser peening process were previously attributable to laser system complexity, processing rates, manual labor and overlay applications. Numerous ongoing advancements addressing these challenges have reduced laser peening costs dramatically: laser peening systems are designed to handle robust operations; pulse rates of laser systems are increasing; routine labor operations are increasingly automated; application of overlays are automated in many cases. These reduced operational costs of laser peening have made it a valuable tool for solving an extended range of fatigue and related applications. | 0 | Metallurgy |
Small molecules, proteins, and nucleic acids have been found to stimulate levels of frameshifting. For example, the mechanism of a negative feedback loop in the polyamine synthesis pathway is based on polyamine levels stimulating an increase in +1 frameshifts, which results in production of an inhibitory enzyme. Certain proteins which are needed for codon recognition or which bind directly to the mRNA sequence have also been shown to modulate frameshifting levels. MicroRNA (miRNA) molecules may hybridize to a RNA secondary structure and affect its strength. | 1 | Gene expression + Signal Transduction |
Dephosphorylation can play a key role in molecular biology, particularly cloning using restriction enzymes. The cut ends of a vector may re-ligate during a ligation step due to phosphorylation. By using a desphosphorylating phosphatase, re-ligation can be avoided. Alkaline phosphatases, which remove the phosphate group present at the 5′ terminus of a DNA molecule, are often sourced naturally, most commonly from calf intestine, and are abbreviated as CIP. | 1 | Gene expression + Signal Transduction |
Pol III is unusual (compared to Pol II) by requiring no control sequences upstream of the gene, instead normally relying on internal control sequences - sequences within the transcribed section of the gene (although upstream sequences are occasionally seen, e.g. U6 snRNA gene has an upstream TATA box as seen in Pol II Promoters).
There are three classes of Pol III initiation, corresponding to 5S rRNA, tRNA, and U6 snRNA initiation. In all cases, the process starts with transcription factors binding to control sequences and ends with TFIIIB (Transcription Factor for polymerase III B) being recruited to the complex and assembling Pol III. TFIIIB consists of three subunits: TATA binding protein (TBP), a TFIIB-related factor (BRF1, or BRF2 for transcription of a subset of Pol III-transcribed genes in vertebrates), and a B-double-prime (BDP1) unit. The overall architecture bears similarities to that of Pol II. | 1 | Gene expression + Signal Transduction |
Award programs highlight copper architecture installations in Canada and the U.S. and in Europe. An International Copper and the Home Competition also exists. Judged by architecture and copper industry experts, criteria for the awards programs include copper in building design, craft of copper installation, excellence in innovation, and historic renovation. | 0 | Metallurgy |
Several manufacturers produce EDM machines for the specific purpose of removing broken cutting tools and fasteners from work pieces. In this application, the process is termed "metal disintegration machining" or MDM. The metal disintegration process removes only the center of the broken tool or fastener, leaving the hole intact and allowing a ruined part to be reclaimed. | 0 | Metallurgy |
In froth flotation, the crushed ore is wetted, suspended in a slurry, and mixed with reagents that render the sulfide particles hydrophobic. Typical reagents ("collectors") include potassium ethylxanthate and sodium ethylxanthate, but dithiophosphates and dithiocarbamates are also used. The slurry is introduced to a water-filled aeration tank containing a surfactant such as methylisobutyl carbinol (MIBC). Air is constantly forced through the slurry. The air bubbles attach to the hydrophobic copper sulfide particles, which are conveyed to the surface where the froth is skimmed off. These skimmings are generally subjected to a cleaner-scavenger cell to remove excess silicates and to remove other sulfide minerals that can deleteriously impact the concentrate quality (typically, galena), and the final concentrate sent for smelting. The rock that has not floated off in the flotation cell is either discarded as tailings or further processed to extract other metals such as lead (from galena) and zinc (from sphalerite), should they exist. A variety of measures are taken to improve the efficiency of the froth flotation. Lime is used to raise the pH of the water bath, causing the collector to bond more efficiently to the copper sulfides. The process can produce a concentrates with 27–29% and 37–40% copper contents from chalcopyrite and chalcocite, respectively. | 0 | Metallurgy |
In a bacterium without the proper mutation(s) in rpoB rifampicin binds to a site near the fork in the β subunit and prevents the polymerase from transcribing more than two or three base pairs of any RNA sequence and stopping production of proteins within the cell. Bacteria with mutations in the proper loci along the rpoB gene are resistant to this effect.
Initial studies were done by Jin and Gross to generate rpoB mutations in E. coli that conferred resistance to rifampicin. Three clusters of mutations were identified, cluster I at codons 507-533, cluster II at codons 563-572, and cluster III at codon 687. The majority of these mutations are located within an 81 base pair(bp) region in cluster I dubbed the "Rifampicin Resistance Determining Region (RRDR)". This resistance is typically associated with a mutation wherein a base in the DNA is substituted for another one and the new sequence codes for an amino acid with a large side chain that inhibits the rifampicin molecules from binding to the polymerase.
There are additional mutations which can occur in the β subunit of the polymerase which are located away from the rifampicin binding site that can also result in mild resistance. Potentially indicating that the shape of these areas may affect the formation of the rifampicin binding site.
Nucleic acid probes can detect mutations in rpoB that confer rifampicin resistance. For Mycobacterium tuberculosis, the rifamycin-resistant mutations most commonly encountered involve codons 516, 526, and 531 (numbered, by convention, as in Escherichia coli rpoB). These mutations result in high rifampicin resistance with a relatively low loss of fitness. For Staphylococcus aureus, the rifamycin-resistant mutation most commonly encountered involves codon 526.
In addition to imparting resistance to rifampicin, certain rpoB mutations have been identified in 70% of Vancomycin Intermediate S. aureus (VISA) strains. | 1 | Gene expression + Signal Transduction |
An increase in permeability usually indicates a more open structure in the rammed sand, and if the increase continues, it will lead to penetration-type defects and rough castings. A decrease in permeability indicates tighter packing and could lead to blows and pinholes. | 0 | Metallurgy |
It is the similar to the bacterial code (translation table 11) but it contains an additional stop codon (TTA) and also has a different set of start codons. | 1 | Gene expression + Signal Transduction |
Casting and forging are traditional metallurgical processing techniques that can be used to generate both polycrystalline and monocrystalline products. Polycrystalline casts offer higher fracture resistance, while monocrystalline casts offer higher creep resistance.
Jet turbine engines employ both crystalline component types to take advantage of their individual strengths. The disks of the high-pressure turbine, which are near the central hub of the engine are polycrystalline. The turbine blades, which extend radially into the engine housing, experience a much greater centripetal force, necessitating creep resistance, typically adopting monocrystalline or polycrystalline with a preferred crystal orientation. | 0 | Metallurgy |
Allelic exclusion is a process of gene expression when one allele is expressed and the other one kept silent. Two most studied cases of allelic exclusion are monoallelic expression of immunoglobulins in B and T cells and olfactory receptors in sensory neurons. Allelic exclusion is cell-type specific (as opposed to organism-wide XCI), which increases intercellular diversity, thus specificity towards certain antigens or odors.
Allele-biased expression is skewed expression level of one allele over the other, but both alleles are still expressed (in contrast to allelic exclusion). This phenomenon is often observed in cells of immune function | 1 | Gene expression + Signal Transduction |
The standard biochemistry and molecular biology textbooks describe non-coding nucleotides in mRNA located between the 5 end of the gene and the translation initiation codon. These regions are called 5-untranslated regions or 5-UTRs. Similar regions called 3-untranslated regions (3-UTRs) are found at the end of the gene. The 5-UTRs and 3UTRs are very short in bacteria but they can be several hundred nucleotides in length in eukaryotes. They contain short elements that control the initiation of translation (5-UTRs) and transcription termination (3'-UTRs) as well as regulatory elements that may control mRNA stability, processing, and targeting to different regions of the cell. | 1 | Gene expression + Signal Transduction |
In physics, the expression noble metal is sometimes confined to copper, silver, and gold, since their full d-subshells contribute to what noble character they have. In contrast, the other noble metals, especially the platinum group metals, have notable catalytic applications, arising from their partially filled d-subshells. This is the case with palladium which has a full d-subshell in the atomic state but in condensed form has a partially filled sp band at the expense of d-band occupancy.
The difference in reactivity can be seen during the preparation of clean metal surfaces in an ultra-high vacuum: surfaces of "physically defined" noble metals (e.g., gold) are easy to clean and keep clean for a long time, while those of platinum or palladium, for example, are covered by carbon monoxide very quickly. | 0 | Metallurgy |
Investment casting (known as lost-wax casting in art) is a process that has been practiced for thousands of years, with the lost-wax process being one of the oldest known metal forming techniques. From 5000 years ago, when beeswax formed the pattern, to today's high technology waxes, refractory materials, and specialist alloys, the castings ensure high-quality components are produced with the key benefits of accuracy, repeatability, versatility, and integrity.
Investment casting derives its name from the fact that the pattern is invested, or surrounded, with a refractory material. The wax patterns require extreme care for they are not strong enough to withstand forces encountered during the mold making. One advantage of investment casting is that the wax can be reused.
The process is suitable for repeatable production of net shape components from a variety of different metals and high performance alloys. Although generally used for small castings, this process has been used to produce complete aircraft door frames, with steel castings of up to 300 kg and aluminium castings of up to 30 kg. Compared to other casting processes such as die casting or sand casting, it can be an expensive process. However, the components that can be produced using investment casting can incorporate intricate contours, and in most cases the components are cast near net shape, so require little or no rework once cast. | 0 | Metallurgy |
Cohen et al. found that of a pair of co-expressed genes only one promoter has an Upstream Activating Sequence (UAS) associated with that expression pattern. They suggested that UASs can activate genes that are not in immediate adjacency to them. This explanation could explain the co-expression of small clusters, but many clusters contain to many genes to be regulated by a single UAS.
Chromatin changes are a plausible explanation for the co-regulation seen in clusters. Chromatin consists of the DNA strand and histones that are attached to the DNA. Regions were chromatin is very tightly packed are called heterochromatin. Heterochromatin consists very often of remains of viral genomes, transposons and other junk DNA. Because of tight packing the DNA is almost unreachable for the transcript machinery, covering deleterious DNA with proteins is the way in which the cell can protect itself. Chromatin which consists of functional genes is often an open structure were the DNA is accessible. However, most of the genes are not needed to be expressed all the time.
DNA with genes that aren't needed can be covered with histones. When a gene must be expressed special proteins can alter the chemical that are attached to the histones (histone modifications) that cause the histones to open the structure. When the chromatin of one gene is opened, the chromatin of the adjacent genes is also until this modification meets a boundary element. In that way genes is close proximity are expressed on the same time. So, genes are clustered in “expression hubs”. In comparison with this model Gilbert et al. (2004) showed that RIDGEs are mostly present in open chromatin structures.
However Johnidis et al. (2005) have shown that genes in the same cluster can be very differently expressed. How eukaryotic gene regulation, and associated chromatin changes, precisely works is still very unclear and there is no consensus about it. In order to get a clear picture about the mechanism of gene clusters first the workings chromatin and gene regulation needs to be illuminated.
Furthermore, most papers that identified clusters of co-regulated genes focused on transcription levels whereas few focused on clusters regulated by the same transcription-factors. Johnides et al. discovered strange phenomena when they did. | 1 | Gene expression + Signal Transduction |
The salt spray test (or salt fog test) is a standardized and popular corrosion test method, used to check corrosion resistance of materials and surface coatings. Usually, the materials to be tested are metallic (although stone, ceramics, and polymers may also be tested) and finished with a surface coating which is intended to provide a degree of corrosion protection to the underlying metal.
Salt spray testing is an accelerated corrosion test that produces a corrosive attack to coated samples in order to evaluate (mostly comparatively) the suitability of the coating for use as a protective finish. The appearance of corrosion products (rust or other oxides) is evaluated after a pre-determined period of time. Test duration depends on the corrosion resistance of the coating; generally, the more corrosion resistant the coating is, the longer the period of testing before the appearance of corrosion or rust.
The salt spray test is one of the most widespread and long-established corrosion tests. ASTMB117 was the first internationally recognized salt spray standard, originally published in 1939. Other important relevant standards are ISO9227, JISZ2371 and ASTMG85. | 0 | Metallurgy |
The rate of cell growth is directly dependent on the rate of protein synthesis, which is itself intricately linked to ribosome synthesis and rRNA transcription. Thus, intracellular signals must coordinate the synthesis of rRNA with that of other components of protein translation. Myc is known to bind to human ribosomal DNA in order to stimulate rRNA transcription by RNA polymerase I. Two specific mechanisms have been identified, ensuring proper control of rRNA synthesis and Pol I-mediated transcription.
Given the large numbers of rDNA genes (several hundreds) available for transcription, the first mechanism involves adjustments in the number of genes being transcribed at a specific time. In mammalian cells, the number of active rDNA genes varies between cell types and level of differentiation. In general, as a cell becomes more differentiated, it requires less growth and, therefore, will have a decrease in rRNA synthesis and a decrease in rDNA genes being transcribed. When rRNA synthesis is stimulated, SL1 (selectivity factor 1) will bind to the promoters of rDNA genes that were previously silent, and recruit a pre-initiation complex to which Pol I will bind and start transcription of rRNA.
Changes in rRNA transcription can also occur via changes in the rate of transcription. While the exact mechanism through which Pol I increases its rate of transcription is as yet unknown, evidence has shown that rRNA synthesis can increase or decrease without changes in the number of actively transcribed rDNA. | 1 | Gene expression + Signal Transduction |
There are four known mammalian protein kinases that phosphorylate eIF2α, including PKR-like ER kinase (PERK, EIF2AK3), heme-regulated eIF2α kinase (HRI, EIF2AK1), general control non-depressible 2 (GCN2, EIF2AK4) and double stranded RNA dependent protein kinase (PKR, EIF2AK2). | 1 | Gene expression + Signal Transduction |
These probes are mostly used to monitor corrosion caused by erosion or wear. Generally, the erosion are occurred in gas pipelines where the speed of fluid cause erosion. Here the erosion is more important than corrosion. | 0 | Metallurgy |
Untranslated regions (UTRs) are sections of the mRNA before the start codon and after the stop codon that are not translated, termed the five prime untranslated region (5 UTR) and three prime untranslated region (3 UTR), respectively. These regions are transcribed with the coding region and thus are exonic as they are present in the mature mRNA. Several roles in gene expression have been attributed to the untranslated regions, including mRNA stability, mRNA localization, and translational efficiency. The ability of a UTR to perform these functions depends on the sequence of the UTR and can differ between mRNAs. Genetic variants in 3' UTR have also been implicated in disease susceptibility because of the change in RNA structure and protein translation.
The stability of mRNAs may be controlled by the 5 UTR and/or 3 UTR due to varying affinity for RNA degrading enzymes called ribonucleases and for ancillary proteins that can promote or inhibit RNA degradation. (See also, C-rich stability element.)
Translational efficiency, including sometimes the complete inhibition of translation, can be controlled by UTRs. Proteins that bind to either the 3 or 5 UTR may affect translation by influencing the ribosomes ability to bind to the mRNA. MicroRNAs bound to the 3 UTR also may affect translational efficiency or mRNA stability.
Cytoplasmic localization of mRNA is thought to be a function of the 3 UTR. Proteins that are needed in a particular region of the cell can also be translated there; in such a case, the 3 UTR may contain sequences that allow the transcript to be localized to this region for translation.
Some of the elements contained in untranslated regions form a characteristic secondary structure when transcribed into RNA. These structural mRNA elements are involved in regulating the mRNA. Some, such as the SECIS element, are targets for proteins to bind. One class of mRNA element, the riboswitches, directly bind small molecules, changing their fold to modify levels of transcription or translation. In these cases, the mRNA regulates itself. | 1 | Gene expression + Signal Transduction |
The gating system serves many purposes, the most important being conveying the liquid material to the mold, but also controlling shrinkage, the speed of the liquid, turbulence, and trapping dross. The gates are usually attached to the thickest part of the casting to assist in controlling shrinkage. In especially large castings multiple gates or runners may be required to introduce metal to more than one point in the mold cavity. The speed of the material is important because if the material is traveling too slowly it can cool before completely filling, leading to misruns and cold shuts. If the material is moving too fast then the liquid material can erode the mold and contaminate the final casting. The shape and length of the gating system can also control how quickly the material cools; short round or square channels minimize heat loss.
The gating system may be designed to minimize turbulence, depending on the material being cast. For example, steel, cast iron, and most copper alloys are turbulent insensitive, but aluminium and magnesium alloys are turbulent sensitive. The turbulent insensitive materials usually have a short and open gating system to fill the mold as quickly as possible. However, for turbulent sensitive materials short sprues are used to minimize the distance the material must fall when entering the mold. Rectangular pouring cups and tapered sprues are used to prevent the formation of a vortex as the material flows into the mold; these vortices tend to suck gas and oxides into the mold. A large sprue well is used to dissipate the kinetic energy of the liquid material as it falls down the sprue, decreasing turbulence. The choke, which is the smallest cross-sectional area in the gating system used to control flow, can be placed near the sprue well to slow down and smooth out the flow. Note that on some molds the choke is still placed on the gates to make separation of the part easier, but induces extreme turbulence. The gates are usually attached to the bottom of the casting to minimize turbulence and splashing.
The gating system may also be designed to trap dross. One method is to take advantage of the fact that some dross has a lower density than the base material so it floats to the top of the gating system. Therefore, long flat runners with gates that exit from the bottom of the runners can trap dross in the runners; note that long flat runners will cool the material more rapidly than round or square runners. For materials where the dross is a similar density to the base material, such as aluminium, runner extensions and runner wells can be advantageous. These take advantage of the fact that the dross is usually located at the beginning of the pour, therefore the runner is extended past the last gate(s) and the contaminates are contained in the wells. Screens or filters may also be used to trap contaminates.
It is important to keep the size of the gating system small, because it all must be cut from the casting and remelted to be reused. The efficiency, or , of a casting system can be calculated by dividing the weight of the casting by the weight of the metal poured. Therefore, the higher the number the more efficient the gating system/risers. | 0 | Metallurgy |
Most diseases are heterogeneous in cause, meaning that one "disease" is often many different diseases at the molecular level, though symptoms exhibited and response to treatment may be identical. How diseases of different molecular origin respond to treatments is partially addressed in the discipline of pharmacogenomics.
Not listed here are the many kinds of cancers involving aberrant transcriptional regulation owing to creation of chimeric genes through pathological chromosomal translocation. Importantly, intervention in the number or structure of promoter-bound proteins is one key to treating a disease without affecting expression of unrelated genes sharing elements with the target gene. Some genes whose change is not desirable are capable of influencing the potential of a cell to become cancerous. | 1 | Gene expression + Signal Transduction |
The aluminothermic reaction is used for the production of several ferroalloys, for example ferroniobium from niobium pentoxide and ferrovanadium from iron, vanadium(V) oxide, and aluminium. The process begins with the reduction of the oxide by the aluminium:
:3 VO + 10 Al → 5 AlO + 6 V
Other metals can be produced from their oxides in the same way.
Aluminothermic reactions have been used for welding rail tracks on-site, useful for complex installations or local repairs that cannot be done using continuously welded rail. Another common use is the welding of copper cables (wire) for use in direct burial (grounding/earthing) applications. It is still the only type of electrical connection recognized by the IEEE (IEEE, Std 80–2001) as continuous un-spliced cable. | 0 | Metallurgy |
After the initial carousel stripping machine development and the later development of the linear stripping machine, Falconbridge personnel developed the Kidd Process High Capacity Linear Machine (“HCLM”). This machine included a loading and unloading system that was based on robotics.
The new design improved, among other things, the discharge area of the stripper. This had been a problem area for the carousel stripping machines, in which copper released from the cathode plate fell into an envelope and was then transferred to a material handling device. Copper that misbehaved and failed to transfer often required manual intervention. The new robot discharge system eliminated the free falling of the copper and physically transferred the released copper to the discharge location. | 0 | Metallurgy |
Ceramography evolved along with other branches of materialography and ceramic engineering. Alois de Widmanstätten of Austria etched a meteorite in 1808 to reveal proeutectoid ferrite bands that grew on prior austenite grain boundaries. Geologist Henry Clifton Sorby, the "father of metallography," applied petrographic techniques to the steel industry in the 1860s in Sheffield, England. French geologist Auguste Michel-Lévy devised a chart that correlated the optical properties of minerals to their transmitted color and thickness in the 1880s. Swedish metallurgist J.A. Brinell invented the first quantitative hardness scale in 1900. Smith and Sandland developed the first microindentation hardness test at Vickers Ltd. in London in 1922. Swiss-born microscopist A.I. Buehler started the first metallographic equipment manufacturer near Chicago in 1936. Frederick Knoop and colleagues at the National Bureau of Standards developed a less-penetrating (than Vickers) microindentation test in 1939. Struers A/S of Copenhagen introduced the electrolytic polisher to metallography in 1943. George Kehl of Columbia University wrote a book that was considered the bible of materialography until the 1980s. Kehl co-founded a group within the Atomic Energy Commission that became the International Metallographic Society in 1967. | 0 | Metallurgy |
Flash smelting () is a smelting process for sulfur-containing ores including chalcopyrite. The process was developed by Outokumpu in Finland and first applied at the Harjavalta plant in 1949 for smelting copper ore. It has also been adapted for nickel and lead production.
A second flash smelting system was developed by the International Nickel Company (INCO) and has a different concentrate feed design compared to the Outokumpu flash furnace. The Inco flash furnace has end-wall concentrate injection burners and a central waste gas off-take, while the Outokumpu flash furnace has a water-cooled reaction shaft at one end of the vessel and a waste gas off-take at the other end. While the INCO flash furnace at Sudbury was the first commercial use of oxygen flash smelting, fewer smelters use the INCO flash furnace than the Outokumpu flash furnace.
Flash smelting with oxygen-enriched air (the reaction gas) makes use of the energy contained in the concentrate to supply most of the energy required by the furnaces. The concentrate must be dried before it is injected into the furnaces and, in the case of the Outokumpu process, some of the furnaces use an optional heater to warm the reaction gas typically to 100–450 °C.
The reactions in the flash smelting furnaces produce copper matte, iron oxides and sulfur dioxide. The reacted particles fall into a bath at the bottom of the furnace, where the iron oxides react with fluxes, such as silica and limestone, to form a slag.
In most cases, the slag can be discarded, perhaps after some cleaning, and the matte is further treated in converters to produce blister copper. In some cases where the flash furnaces are fed with concentrate containing a sufficiently high copper content, the concentrate is converted directly to blister in a single Outokumpu furnace and further converting is unnecessary.
The sulfur dioxide produced by flash smelting is typically captured in a sulfuric acid plant, removing the major environmental effect of smelting.
Outotec, formerly the technology division of Outokumpu, now holds Outokumpu's patents to the technology and licenses it worldwide.
INCO was acquired by Brazil's Vale in 2006. | 0 | Metallurgy |
The eyespot apparatus (or stigma) is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids. It allows the cells to sense light direction and intensity and respond to it, prompting the organism to either swim towards the light (positive phototaxis), or away from it (negative phototaxis). A related response ("photoshock" or photophobic response) occurs when cells are briefly exposed to high light intensity, causing the cell to stop, briefly swim backwards, then change swimming direction. Eyespot-mediated light perception helps the cells in finding an environment with optimal light conditions for photosynthesis. Eyespots are the simplest and most common "eyes" found in nature, composed of photoreceptors and areas of bright orange-red red pigment granules. Signals relayed from the eyespot photoreceptors result in alteration of the beating pattern of the flagella, generating a phototactic response. | 1 | Gene expression + Signal Transduction |
The development, differentiation and growth of cells and tissues require precisely regulated patterns of gene expression. Enhancers work as cis-regulatory elements to mediate both spatial and temporal control of development by turning on transcription in specific cells and/or repressing it in other cells. Thus, the particular combination of transcription factors and other DNA-binding proteins in a developing tissue controls which genes will be expressed in that tissue. Enhancers allow the same gene to be used in diverse processes in space and time. | 1 | Gene expression + Signal Transduction |
The properties of ferromanganese vary considerably with the precise type and composition of the alloy. The melting point is generally between and . The density of the alloy depend slightly on the types of impurities present, but is generally around . | 0 | Metallurgy |
Gold working in the Bronze Age British Isles refers to the use of gold to produce ornaments and other prestige items in the British Isles during the Bronze Age, between and in Britain, and up to about 550 BCE in Ireland. In this period, communities in Britain and Ireland first learned how to work metal, leading to the widespread creation of not only gold but also copper and bronze items as well. Gold artefacts in particular were prestige items used to designate the high status of those individuals who wore, or were buried with them.
Around 1,500 gold objects dating to the Bronze Age survive in collections, around 1000 of them from Ireland and the other 500 from Britain; this is a much smaller number than would have been originally crafted, leading archaeologists to believe that "many thousands of gold objects were made and used" in the Bronze Age British Isles.
Records indicate that Bronze Age gold artefacts had begun to be discovered by the 18th century at the least, although at the time many were melted down or lost. Only with the rise of the antiquarian and then archaeological movements were the antiquity of these items recognised, after which they were more usually preserved in collections.
The archaeologist George Eogan noted that investigation of Bronze Age gold artefacts revealed not only "the work of craftsmen and technicians" from that period but also aided our understanding of "broader aspects of society such as social stratification, trade, commerce and ritual." | 0 | Metallurgy |
Eukaryotes have multiple types of nuclear RNAP, each responsible for synthesis of a distinct subset of RNA. All are structurally and mechanistically related to each other and to bacterial RNAP:
Eukaryotic chloroplasts contain an RNAP very highly similar to bacterial RNAP ("plastid-encoded polymerase, PEP"). They use sigma factors encoded in the nuclear genome.
Chloroplast also contain a second, structurally and mechanistically unrelated, single-subunit RNAP ("nucleus-encoded polymerase, NEP"). Eukaryotic mitochondria use POLRMT (human), a nucleus-encoded single-subunit RNAP. Such phage-like polymerases are referred to as RpoT in plants. | 1 | Gene expression + Signal Transduction |
The alloys did not prove to be commercially successful in the long run. However, during World War I and afterwards, uranium-doped steels were used for tools; large amounts of ferrouranium were produced between 1914 and 1916. | 0 | Metallurgy |
Replication timing domains have been shown to be associated with TADs as their boundary is co localized with the boundaries of TADs that are located at either sides of compartments. Insulated neighborhoods, DNA loops formed by CTCF/cohesin-bound regions, are proposed to functionally underlie TADs. | 1 | Gene expression + Signal Transduction |
In spark plasma sintering (SPS), external pressure and an electric field are applied simultaneously to enhance the densification of the metallic/ceramic powder compacts. However, after commercialization it was determined there is no plasma, so the proper name is spark sintering as coined by Lenel. The electric field driven densification supplements sintering with a form of hot pressing, to enable lower temperatures and taking less time than typical sintering. For a number of years, it was speculated that the existence of sparks or plasma between particles could aid sintering; however, Hulbert and coworkers systematically proved that the electric parameters used during spark plasma sintering make it (highly) unlikely. In light of this, the name "spark plasma sintering" has been rendered obsolete. Terms such as field assisted sintering technique (FAST), electric field assisted sintering (EFAS), and direct current sintering (DCS) have been implemented by the sintering community. Using a direct current (DC) pulse as the electric current, spark plasma, spark impact pressure, joule heating, and an electrical field diffusion effect would be created. By modifying the graphite die design and its assembly, it is possible to perform pressureless sintering in spark plasma sintering facility. This modified die design setup is reported to synergize the advantages of both conventional pressureless sintering and spark plasma sintering techniques. | 0 | Metallurgy |
Explanation of diauxie depended on the characterization of additional mutations affecting the lac genes other than those explained by the classical model. Two other genes, cya and crp, subsequently were identified that mapped far from lac, and that, when mutated, result in a decreased level of expression in the presence of IPTG and even in strains of the bacterium lacking the repressor or operator. The discovery of cAMP in E. coli led to the demonstration that mutants defective the cya gene but not the crp gene could be restored to full activity by the addition of cAMP to the medium.
The cya gene encodes adenylate cyclase, which produces cAMP. In a cya mutant, the absence of cAMP makes the expression of the lacZYA genes more than ten times lower than normal. Addition of cAMP corrects the low Lac expression characteristic of cya mutants. The second gene, crp, encodes a protein called catabolite activator protein (CAP) or cAMP receptor protein (CRP).
However the lactose metabolism enzymes are made in small quantities in the presence of both glucose and lactose (sometimes called leaky expression) due to the fact that the RNAP can still sometimes bind and initiate transcription even in the absence of CAP. Leaky expression is necessary in order to allow for metabolism of some lactose after the glucose source is expended, but before lac expression is fully activated.
In summary:
* When lactose is absent then there is very little Lac enzyme production (the operator has Lac repressor bound to it).
* When lactose is present but a preferred carbon source (like glucose) is also present then a small amount of enzyme is produced (Lac repressor is not bound to the operator).
* When glucose is absent, CAP-cAMP binds to a specific DNA site upstream of the promoter and makes a direct protein-protein interaction with RNAP that facilitates the binding of RNAP to the promoter.
The delay between growth phases reflects the time needed to produce sufficient quantities of lactose-metabolizing enzymes. First, the CAP regulatory protein has to assemble on the lac promoter, resulting in an increase in the production of lac mRNA. More available copies of the lac mRNA results in the production (see translation) of significantly more copies of LacZ (β-galactosidase, for lactose metabolism) and LacY (lactose permease to transport lactose into the cell). After a delay needed to increase the level of the lactose metabolizing enzymes, the bacteria enter into a new rapid phase of cell growth.
Two puzzles of catabolite repression relate to how cAMP levels are coupled to the presence of glucose, and secondly, why the cells should even bother. After lactose is cleaved it actually forms glucose and galactose (easily converted to glucose). In metabolic terms, lactose is just as good a carbon and energy source as glucose. The cAMP level is related not to intracellular glucose concentration but to the rate of glucose transport, which influences the activity of adenylate cyclase. (In addition, glucose transport also leads to direct inhibition of the lactose permease.) As to why E. coli works this way, one can only speculate. All enteric bacteria ferment glucose, which suggests they encounter it frequently. It is possible that a small difference in efficiency of transport or metabolism of glucose v. lactose makes it advantageous for cells to regulate the lac operon in this way. | 1 | Gene expression + Signal Transduction |
A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of the Seebeck effect, and this voltage can be interpreted to measure temperature. Thermocouples are widely used as temperature sensors.
Commercial thermocouples are inexpensive, interchangeable, are supplied with standard connectors, and can measure a wide range of temperatures. In contrast to most other methods of temperature measurement, thermocouples are self-powered and require no external form of excitation. The main limitation with thermocouples is accuracy; system errors of less than one degree Celsius (°C) can be difficult to achieve.
Thermocouples are widely used in science and industry. Applications include temperature measurement for kilns, gas turbine exhaust, diesel engines, and other industrial processes. Thermocouples are also used in homes, offices and businesses as the temperature sensors in thermostats, and also as flame sensors in safety devices for gas-powered appliances. | 0 | Metallurgy |
It was proposed that increased synthesis of (p)ppGpp would cause polyphosphate (PolyP) accumulation in E. coli. The alarmone could interact with exopolyphosphatase PPX, which would inhibit the hydrolysis of PolyP, thus causing its accumulation in bacteria. Although it has recently been shown that it is actually DksA and not (p)ppGpp that causes this buildup. It has been shown in Pseudomonas aeruginosa that the phoU mutant (phoU belongs to the Pho Regulon) synthesizes more (p)ppGpp and this would be one of the reasons that it accumulates more polyphosphate. | 1 | Gene expression + Signal Transduction |
Silicon carbide is used in carborundum printmaking – a collagraph printmaking technique. Carborundum grit is applied in a paste to the surface of an aluminium plate. When the paste is dry, ink is applied and trapped in its granular surface, then wiped from the bare areas of the plate. The ink plate is then printed onto paper in a rolling-bed press used for intaglio printmaking. The result is a print of painted marks embossed into the paper.
Carborundum grit is also used in stone Lithography. Its uniform particle size allows it to be used to "Grain" a stone which removes the previous image. In a similar process to sanding, coarser grit Carborundum is applied to the stone and worked with a Levigator, typically a round plate eccentric on a perpendicular shaft, then gradually finer and finer grit is applied until the stone is clean. This creates a grease sensitive surface. | 0 | Metallurgy |
Phosphate groups can exist in three different forms depending on a solution's pH. Phosphorus atoms can bind three oxygen atoms with single bonds and a fourth oxygen atom using a double/dative bond. The pH of the solution, and thus the form of the phosphate group determines its ability to bind to other molecules. The binding of phosphate groups to the inositol ring is accomplished by phosphor-ester binding (see phosphoric acids and phosphates). This bond involves combining a hydroxyl group from the inositol ring and a free phosphate group through a dehydration reaction. Considering that the average physiological pH is approximately 7.4, the main form of the phosphate groups bound to the inositol ring in vivo is PO. This gives IP a net negative charge, which is important in allowing it to dock to its receptor, through binding of the phosphate groups to positively charged residues on the receptor. IP has three hydrogen bond donors in the form of its three hydroxyl groups. The hydroxyl group on the 6th carbon atom in the inositol ring is also involved in IP docking. | 1 | Gene expression + Signal Transduction |
Sewer network structures are prone to biodeterioration of materials due to the action of some microorganisms associated to the sulfur cycle. It can be a severely damaging phenomenon which was firstly described by Olmstead and Hamlin in 1900 for a brick sewer located in Los Angeles. Jointed mortar between the bricks disintegrated and ironwork was heavily rusted. The mortar joint had ballooned to two to three times its original volume, leading to the destruction or the loosening of some bricks.
Around 9% of damages described in sewer networks can be ascribed to the successive action of two kinds of microorganisms. Sulfate-reducing bacteria (SRB) can grow in relatively thick layers of sedimentary sludge and sand (typically 1 mm thick) accumulating at the bottom of the pipes and characterized by anoxic conditions. They can grow using oxidized sulfur compounds present in the effluent as electron acceptor and excrete hydrogen sulfide (HS). This gas is then emitted in the aerial part of the pipe and can impact the structure in two ways: either directly by reacting with the material and leading to a decrease in pH, or indirectly through its use as a nutrient by sulfur-oxidizing bacteria (SOB), growing in oxic conditions, which produce biogenic sulfuric acid. The structure is then submitted to a biogenic sulfuric acid attack. Materials like calcium aluminate cements, PVC or vitrified clay pipe may be substituted for ordinary concrete or steel sewers that are not resistant in these environments.
Mild steel corrosion reduction in water by uptake of dissolved oxygen is carried out by Rhodotorula mucilaginosa(7). | 0 | Metallurgy |
The involvement of toll signalling in immunity was first demonstrated in the fruit fly, Drosophila melanogaster. Fruit flies have only innate immune responses allowing studies to avoid interference of adaptive immune mechanisms on signal transduction. The fly response to fungal or bacterial infection occurs through two distinct signalling cascades, one of which is the toll pathway and the other is the immune deficiency pathway. The toll pathway is similar to mammalian TLR signalling, but unlike mammalian TLRs, toll is not activated directly by pathogen-associated molecular patterns (PAMPs). Its receptor ectodomain recognizes the cleaved form of the cytokine spätzle, which is secreted in the haemolymph as an inactive dimeric precursor. The toll receptor shares the cytoplasmatic TIR domain with mammalian TLRs, but the ectodomain and intracytoplasmatic tail are different. This difference might reflect a function of these receptors as cytokine receptors rather than PRRs.
The toll pathway is activated by different stimuli, such as Gram positive bacteria, fungi and virulence factors. First, the Spätzle processing enzyme (SPE) is activated in response to infection and cleaves spätzle (spz). Cleaved spätzle then binds to the toll receptor and crosslinks its ectodomains. This triggers conformational changes in the receptor resulting in signalling through toll. From this point forward, the signalling cascade is very similar to mammalian signalling through TLRs. The toll-induced signalling complex (TICS) is composed of MyD88, Tube, and Pelle (the orthologue of mammalian IRAK). Signal from TICS is then transduced to Cactus (homologue of mammalian IκB), phosphorylated Cactus is polyubiquitylated and degraded, allowing nuclear translocation of DIF (dorsal-related immunity factor; a homologue of mammalian NF-κB) and induction of transcription of genes for antimicrobial peptides (AMPs) such as drosomycin.
Drosophila have a total of 9 toll family and 6 spz family genes that interact with each other to differing degrees. | 1 | Gene expression + Signal Transduction |
Online non-intrusive ultrasonic thickness sensors are a popular choice for corrosion monitoring in various industries, including oil and gas, chemical processing, and power generation. These sensors can provide accurate and reliable thickness measurements of metal structures without requiring physical access or disruption to the equipment. The sensors can be installed permanently and remotely connected to a monitoring system, allowing for continuous data collection and analysis. With the ability to detect corrosion early on, online ultrasonic thickness sensors can help prevent equipment failure, reduce downtime, and improve overall safety and efficiency. | 0 | Metallurgy |
In neuroscience and anatomy, nodes of Ranvier ( ), also known as myelin-sheath gaps, occur along a myelinated axon where the axolemma is exposed to the extracellular space. Nodes of Ranvier are uninsulated and highly enriched in ion channels, allowing them to participate in the exchange of ions required to regenerate the action potential. Nerve conduction in myelinated axons is referred to as saltatory conduction () due to the manner in which the action potential seems to "jump" from one node to the next along the axon. This results in faster conduction of the action potential. | 1 | Gene expression + Signal Transduction |
hnRNP C is a key regulator of the BRCA1 and BRCA2 genes. In response to ionizing radiation, hnRNP C partially localizes to the site of DNA damage, and when depleted, S-phase progression of the cell is impaired. Additionally, BRCA1 and BRCA2 levels fall when hnRNP C is lost. BRCA1 and BRCA2 are crucial tumor-suppressor genes which are strongly implicated in breast cancers when mutated. BRCA1 in particular causes G2/M cell cycle arrest in response to DNA damage via the CHEK1 signaling cascade. hnRNP C is important for the proper expression of other tumor suppressor genes including RAD51 and BRIP1 as well. Through these genes, hnRNP is necessary to induce cell-cycle arrest in response to DNA damage by ionizing radiation. | 1 | Gene expression + Signal Transduction |
Yonekura shows the steel industry was central to the economic development of Japan. The nation's sudden transformation from feudal to modern society in the late nineteenth century, its heavy industrialization and imperialist war ventures in 1900–1945, and the post-World War II high-economic growth, all depended on iron and steel. The other great Japanese industries, such as shipbuilding, automobiles, and industrial machinery are closely linked to steel. From 1850 to 1970, the industry increased its crude steel production from virtually nothing to 93.3 million tons (the third largest in the world).
The government's activist Ministry of International Trade and Industry (MITI) played a major role in coordination. The transfer of technology from the West and the establishment of competitive firms involved far more than buying foreign hardware. MITI located steel mills and organized a domestic market; it sponsored Yawata Steel Company. Japanese engineers and entrepreneurs internally developed the necessary technological and organizational capabilities, planned the transfer and adoption of technology, and gauged demand and sources of raw materials and finances. | 0 | Metallurgy |
Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. The field is a materials science, covering all aspects of the types of ore, washing, concentration, separation, chemical processes and extraction of pure metal and their alloying to suit various applications, sometimes for direct use as a finished product, but more often in a form that requires further working to achieve the given properties to suit the applications.
The field of ferrous and non-ferrous extractive metallurgy have specialties that are generically grouped into the categories of mineral processing, hydrometallurgy, pyrometallurgy, and electrometallurgy based on the process adopted to extract the metal. Several processes are used for extraction of the same metal depending on occurrence and chemical requirements. | 0 | Metallurgy |
Nuclear receptors bind to coactivators in a ligand-dependent manner. A common feature of nuclear receptor coactivators is that they contain one or more LXXLL binding motifs (a contiguous sequence of 5 amino acids where L = leucine and X = any amino acid) referred to as NR (nuclear receptor) boxes. The LXXLL binding motifs have been shown by X-ray crystallography to bind to a groove on the surface of ligand binding domain of nuclear receptors. Examples include:
* ARA (androgen receptor associated protein)
** ARA54 ()
** ARA55 ()
** ARA70 ()
* AIRE
* BCAS3 (breast carcinoma amplified sequence 3)
* CREB-binding protein
* CRTC (CREB regulated transcription coactivator)
** CRTC1 ()
** CRTC2 ()
** CRTC3 ()
* CARM1 (coactivator-associated arginine methyltransferase 1)
* Nuclear receptor coactivator (NCOA)
** NCOA1/SRC-1 (steroid receptor coactivator-1)/
** NCOA2/GRIP1 (glucocorticoid receptor interacting protein 1)/ TIF2 (transcriptional intermediary factor 2)
** NCOA3/AIB1 (amplified in breast)
** NCOA4/ARA70 (androgen receptor associated protein 70)
** NCOA5 ()
** NCOA6 ()
** NCOA7 ()
* p300
* PCAF (p300/CBP associating factor)
* PGC1 (proliferator activated receptor gamma coactivator 1)
** PPARGC1A ()
** PPARGC1B ()
* PNRC (proline-rich nuclear receptor coactivator 1)
** PNRC1 ()
** PNRC2 () | 1 | Gene expression + Signal Transduction |
Gene structure is the organisation of specialised sequence elements within a gene. Genes contain most of the information necessary for living cells to survive and reproduce. In most organisms, genes are made of DNA, where the particular DNA sequence determines the function of the gene. A gene is transcribed (copied) from DNA into RNA, which can either be non-coding (ncRNA) with a direct function, or an intermediate messenger (mRNA) that is then translated into protein. Each of these steps is controlled by specific sequence elements, or regions, within the gene. Every gene, therefore, requires multiple sequence elements to be functional. This includes the sequence that actually encodes the functional protein or ncRNA, as well as multiple regulatory sequence regions. These regions may be as short as a few base pairs, up to many thousands of base pairs long.
Much of gene structure is broadly similar between eukaryotes and prokaryotes. These common elements largely result from the shared ancestry of cellular life in organisms over 2 billion years ago. Key differences in gene structure between eukaryotes and prokaryotes reflect their divergent transcription and translation machinery. Understanding gene structure is the foundation of understanding gene annotation, expression, and function. | 1 | Gene expression + Signal Transduction |
Vesicular monoamine transporter 1 (VMAT1) also known as chromaffin granule amine transporter (CGAT) or solute carrier family 18 member 1 (SLC18A1) is a protein that in humans is encoded by the SLC18A1 gene. VMAT1 is an integral membrane protein, which is embedded in synaptic vesicles and serves to transfer monoamines, such as norepinephrine, epinephrine, dopamine, and serotonin, between the cytosol and synaptic vesicles. SLC18A1 is an isoform of the vesicular monoamine transporter. | 1 | Gene expression + Signal Transduction |
An inclusion is a solid particle in liquid aluminium alloy. It is usually non-metallic and can be of different nature depending on its source. | 0 | Metallurgy |
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca, and the binding of Ca is required for the activation of calmodulin. Once bound to Ca, calmodulin acts as part of a calcium signal transduction pathway by modifying its interactions with various target proteins such as kinases or phosphatases. | 1 | Gene expression + Signal Transduction |
Hydrometallurgy is a technique within the field of extractive metallurgy, the obtaining of metals from their ores. Hydrometallurgy involve the use of aqueous solutions for the recovery of metals from ores, concentrates, and recycled or residual materials. Processing techniques that complement hydrometallurgy are pyrometallurgy, vapour metallurgy, and molten salt electrometallurgy. Hydrometallurgy is typically divided into three general areas:
*Leaching
*Solution concentration and purification
*Metal or metal compound recovery | 0 | Metallurgy |
Calciothermic reactions are metallothermic reduction reactions (more generally, thermic chemical reactions) which use calcium metal as the reducing agent at high temperature.
Calcium is one of the most potent reducing agents available, usually drawn as the strongest oxidic reductant in Ellingham diagrams, though the lanthanides best it in this respect in oxide processes. On the other hand, this trend does not continue to other compounds that are non-oxides, and for instance lanthanum is produced by the calciothermic reduction of the chloride, calcium being a more potent reducing agent than lanthanum involving chlorides.
Calciothermic processes are used in the extraction of metals such as uranium, zirconium, and thorium from oxide ores.
An interesting way of performing calciothermic reductions is by in-situ generated metallic calcium, dissolved in molten calcium chloride, as shown in the FFC Cambridge Process. | 0 | Metallurgy |
Once correctly positioned in the membrane via binding of PIP3, Akt can then be phosphorylated by its activating kinases, phosphoinositide-dependent kinase 1 (PDK1) and PDK2. Serine473, the hydrophobic motif, is phosphorylated in an mTORC2-dependent manner, leading some investigators to hypothesize that mTORC2 is the long-sought PDK2 molecule. Threonine308, the activation loop, is phosphorylated by PDK1, allowing full Akt activation. Activated Akt can then go on to activate or deactivate its myriad substrates via its kinase activity. The PHLPPs therefore antagonize PDK1 and PDK2, since they dephosphorylate the site that PDK2 phosphorylates. | 1 | Gene expression + Signal Transduction |
As austenite cools, the carbon diffuses out of the austenite and forms carbon-rich iron-carbide (cementite) and leaves behind carbon-poor ferrite. Depending on alloy composition, a layering of ferrite and cementite, called pearlite, may form. If the rate of cooling is very swift, the carbon does not have sufficient time to diffuse, and the alloy may experience a large lattice distortion known as martensitic transformation in which it transforms into martensite, a body centered tetragonal structure (BCT). The rate of cooling determines the relative proportions of martensite, ferrite, and cementite, and therefore determines the mechanical properties of the resulting steel, such as hardness and tensile strength.
A high cooling rate of thick sections will cause a steep thermal gradient in the material. The outer layers of the heat treated part will cool faster and shrink more, causing it to be under tension and thermal straining. At high cooling rates, the material will transform from austenite to martensite which is much harder and will generate cracks at much lower strains. The volume change (martensite is less dense than austenite) can generate stresses as well. The difference in strain rates of the inner and outer portion of the part may cause cracks to develop in the outer portion, compelling the use of slower quenching rates to avoid this. By alloying the steel with tungsten, the carbon diffusion is slowed and the transformation to BCT allotrope occurs at lower temperatures, thereby avoiding the cracking. Such a material is said to have its hardenability increased. Tempering following quenching will transform some of the brittle martensite into tempered martensite. If a low-hardenability steel is quenched, a significant amount of austenite will be retained in the microstructure, leaving the steel with internal stresses that leave the product prone to sudden fracture. | 0 | Metallurgy |
In crystalline metals, slip occurs in specific directions on crystallographic planes, and each combination of slip direction and slip plane will have its own Schmid factor. As an example, for a face-centered cubic (FCC) system the primary slip plane is {111} and primary slip directions exist within the direction, along the primary slip plane of , with the critical applied shear stress acting in the direction can be calculated by quickly determining if any of the dot product between the axial applied stress and slip plane, or dot product of axial applied stress and shear stress direction equal to zero. For the example cited above, the dot product of axial applied stress in the direction and shear stress resulting from the former in the direction yields a zero. For such a case, it is suitable to find a permutation of the family of the permutation direction for the shear stress slip direction has been chosen:
In a single crystal sample, the macroscopic yield stress will be determined by the Schmid factor of the single grain. Thus, in general, different yield strengths will be observed for applied stresses along different crystallographic directions. In polycrystalline specimens, the yield strength of each grain is different depending on its maximum Schmid factor, which indicates the operational slip system(s). The macroscopically observed yield stress will be related to the material's CRSS by an average Schmid factor, which is roughly 1/3.06 for FCC and 1/2.75 for body-centered cubic (BCC) structures.
The onset of plasticity in polycrystals is influenced by the number of available slip systems to accommodate incompatibilities at the grain boundaries. In the case of two adjacent, randomly oriented grains, one grain will have a larger Schmid factor and thus a smaller yield stress. Under load, this "weaker" grain will yield prior to the "stronger" grain, and as it deforms a stress concentration will build up in the stronger grain near the boundary between them. This stress concentration will activate dislocation motion in the available glide planes. These dislocations are geometrically necessary to ensure that the strain in each grain is equivalent at the grain boundary, so that the compatibility criteria are satisfied. G. I. Taylor showed that a minimum of five active slip systems are required to accommodate an arbitrary deformation. In crystal structures with fewer than 5 active slip systems, such as hexagonal close-packed (HCP) metals, the specimen will exhibit brittle failure instead of plastic deformation. | 0 | Metallurgy |
Nanocrystalline materials show exceptional mechanical properties relative to their coarse-grained varieties. Because the volume fraction of grain boundaries in nanocrystalline materials can be as large as 30%, the mechanical properties of nanocrystalline materials are significantly influenced by this amorphous grain boundary phase. For example, the elastic modulus has been shown to decrease by 30% for nanocrystalline metals and more than 50% for nanocrystalline ionic materials. This is because the amorphous grain boundary regions are less dense than the crystalline grains, and thus have a larger volume per atom, . Assuming the interatomic potential, , is the same within the grain boundaries as in the bulk grains, the elastic modulus, , will be smaller in the grain boundary regions than in the bulk grains. Thus, via the rule of mixtures, a nanocrystalline material will have a lower elastic modulus than its bulk crystalline form. | 0 | Metallurgy |
Shell molding is similar to sand casting, but the molding cavity is formed by a hardened "shell" of sand instead of a flask filled with sand. The sand used is finer than sand casting sand and is mixed with a resin so that it can be heated by the pattern and hardened into a shell around the pattern. Because of the resin and finer sand, it gives a much finer surface finish. The process is easily automated and more precise than sand casting. Common metals that are cast include cast iron, aluminium, magnesium, and copper alloys. This process is ideal for complex items that are small to medium-sized. | 0 | Metallurgy |
The chlorophycean mitochondrial code (translation table 16) is a genetic code found in the mitochondria of Chlorophyceae. | 1 | Gene expression + Signal Transduction |
The nines are a count of the leftmost digits 9 that appear in a proportion. For example, 90% would be described as "one nine"; 99% as "two nines"; 99.9% as "three nines"; and so forth.
However, there are different conventions for representing inexact multiples of 9. For example, a percentage of 99.5% could be expressed as "two nines five" (2N5, or N2.5) or as 2.3 nines, following from the logarithm definition.
A percentage of 100% would, in theory, have an infinite number of nines – though, in the context of purity of materials, 100% is virtually unachievable.
The number of nines of a proportion is: | 0 | Metallurgy |
Sponge iron is not useful by itself, but can be processed to create wrought iron or steel. The sponge is removed from the furnace, called a bloomery, and repeatedly beaten with heavy hammers and folded over to remove the slag, oxidize any carbon or carbide, and weld the iron together. This treatment usually creates wrought iron with about three percent slag and a fraction of a percent of other impurities. Further treatment may add controlled amounts of carbon, allowing various kinds of heat treatment (e.g. "steeling").
Today, sponge iron is created by reducing iron ore without melting it. This makes for an energy-efficient feedstock for specialty steel manufacturers which used to rely upon scrap metal. | 0 | Metallurgy |
As in any technology that has long been conducted on the multi-million ton per year scale, flotation technologies have the potential to threaten the environment beyond the disruption caused by mining. Froth flotation employs a host of organic chemicals and relies upon elaborate machinery. Some of the chemicals (cyanide) are acutely toxic but hydrolyze to innocuous products. Naturally occurring fatty acids are widely used. Tailings and effluents are contained in lined ponds. Froth flotation is "poised for increased activity due to their potential usefulness in environmental site cleanup operations" including recycling of plastics and metals, not to mention water treatment. | 0 | Metallurgy |
Janot was a French Government Overseas Fellow in 1981 at Churchill College, University of Cambridge. He was also a visiting professor at Sapienza University of Rome. | 0 | Metallurgy |
Though the specific mechanisms by which paramutation acts vary from organism to organism, all well-documented cases point towards epigenetic modification and RNA-silencing as the underlying mechanism for paramutation.
In the case of the r1 locus in maize, DNA methylation of a region of tandem repeats near the coding region of the gene is characteristic of the paramutagenic B’ allele, and when the paramutable B-I allele becomes paramutagenic, it too takes on the same DNA methylation pattern. In order for this methylation to be successfully transferred, a number of genes coding for RNA-dependent RNA polymerases and other components of RNA-silencing pathways are required, suggesting that paramutation is mediated via endogenous RNA-silencing pathways. The transcription of short interfering RNAs from the tandem repeat regions corroborates this. In animal systems such as Drosophila, piRNAs have also been implicated in mediating paramutation. In addition to the characteristic DNA methylation state changes, changes in histone modification patterns in the methylated DNA regions, and/or the requirement of histone modifying proteins to mediate paramutation have also been noted in multiple systems. It has been suggested that these histone modifications play a role in maintaining the paramutated state. The previously mentioned tandem repeat region in the r1 locus is also typical of other loci showing paramutation or paramutation-like phenomena.
However, it has been noted that it is not possible to explain all occurrences and features of paramutation with what is known about RNAi-mediated transcriptional silencing, suggesting that other pathways and/or mechanisms are also at play. | 1 | Gene expression + Signal Transduction |
Extremely high temperatures are reached by the D-gun (≈4000 °C) whilst in operation. Flammable and explosive fuels (generally acetylene) are used in detonation spraying to produce the supersonic shockwave that propels the powder coating materials onto their target components. This poses a serious burn and explosion hazard. Again, no-one should be present in the room whilst the D-gun is in operation and the room should be designed to withstand any malfunction of the D-gun. Also protective gloves should be used to handle the D-gun and sprayed components to void burns form hot components after spraying. | 0 | Metallurgy |
G proteins, also known as guanine nucleotide-binding proteins, are a family of proteins that act as molecular switches inside cells, and are involved in transmitting signals from a variety of stimuli outside a cell to its interior. Their activity is regulated by factors that control their ability to bind to and hydrolyze guanosine triphosphate (GTP) to guanosine diphosphate (GDP). When they are bound to GTP, they are on, and, when they are bound to GDP, they are off. G proteins belong to the larger group of enzymes called GTPases.
There are two classes of G proteins. The first function as monomeric small GTPases (small G-proteins), while the second function as heterotrimeric G protein complexes. The latter class of complexes is made up of alpha (G), beta (G) and gamma (G) subunits. In addition, the beta and gamma subunits can form a stable dimeric complex referred to as the beta-gamma complex
Heterotrimeric G proteins located within the cell are activated by G protein-coupled receptors (GPCRs) that span the cell membrane. Signaling molecules bind to a domain of the GPCR located outside the cell, and an intracellular GPCR domain then in turn activates a particular G protein. Some active-state GPCRs have also been shown to be "pre-coupled" with G proteins, whereas in other cases a collision coupling mechanism is thought to occur. The G protein triggers a cascade of further signaling events that finally results in a change in cell function. G protein-coupled receptors and G proteins working together transmit signals from many hormones, neurotransmitters, and other signaling factors. G proteins regulate metabolic enzymes, ion channels, transporter proteins, and other parts of the cell machinery, controlling transcription, motility, contractility, and secretion, which in turn regulate diverse systemic functions such as embryonic development, learning and memory, and homeostasis. | 1 | Gene expression + Signal Transduction |
The ropB protein binding location lies adjacent to speB promoter 1 that is also located within the highly repetitive intergenic region, however the ropB gene and the speB gene are transcribed in opposite directions. The -10 and -35 regions of speB promoter 1 have poor consensus; in order to ameliorate this, the ropB aids the RNA polymerase bondage with the help of a polyU polypyrimidine tract inside the palindromic inverted repeat region in a fashion uncannily similar to intrinsic termination in E.coli. | 1 | Gene expression + Signal Transduction |
Nitinol is exceedingly difficult to make, due to the exceptionally tight compositional control required, and the tremendous reactivity of titanium. Every atom of titanium that combines with oxygen or carbon is an atom that is robbed from the NiTi lattice, thus shifting the composition and making the transformation temperature lower.
There are two primary melting methods used today. Vacuum arc remelting (VAR) is done by striking an electrical arc between the raw material and a water-cooled copper strike plate. Melting is done in a high vacuum, and the mold itself is water-cooled copper. Vacuum induction melting (VIM) is done by using alternating magnetic fields to heat the raw materials in a crucible (generally carbon). This is also done in a high vacuum. While both methods have advantages, it has been demonstrated that an industrial state-of-the-art VIM melted material has smaller inclusions than an industrial state-of-the-art VAR one, leading to a higher fatigue resistance. Other research report that VAR employing extreme high-purity raw materials may lead to a reduced number of inclusions and thus to an improved fatigue behavior. Other methods are also used on a boutique scale, including plasma arc melting, induction skull melting, and e-beam melting. Physical vapour deposition is also used on a laboratory scale.
Heat treating nitinol is delicate and critical. It is a knowledge intensive process to fine-tune the transformation temperatures. Aging time and temperature controls the precipitation of various Ni-rich phases, and thus controls how much nickel resides in the NiTi lattice; by depleting the matrix of nickel, aging increases the transformation temperature. The combination of heat treatment and cold working is essential in controlling the properties of nitinol products. | 0 | Metallurgy |
The conservative nature of gene deserts confirms that these stretches of noncoding bases are essential to proper functioning. Indeed, a wide range of studies on irregularities in the noncoding genes discovered several associations to genetic diseases. One of the most studied gene deserts is the 8q24 region. Early genome wide association studies were focused on the 8q24 region (residing on chromosome 8) due to the abnormally high rates of SNPs that seem to occur in the region. These studies found that the region was linked to increased risks for a variety of cancers, notably in the prostate, breast, ovaries, colonic, and pancreas. Using inserts of the gene desert into bacterial artificial chromosomes, one study was able to produce enhancer activity in certain regions, which were isolated via cloning systems. This study successfully identified an enhancer sequence hidden in the region. Within this enhancer sequence, an SNP that conferred risk for prostate cancer, labeled SNP s6983267, was discovered in diseased mice. However, the 8q24 region is not solely limited to conferred risks of prostate cancer. A study in 2008 screened human subjects (and controls) with variations in the gene desert region, discovering five different regions that conferred different risks when affected by different SNPs. This study used identified SNP markers in the gene desert to identify risk conference from each of the regions to a specific tissue expression. Although these risks were successfully linked to various forms of cancer, Ghoussaini, M., et al. note their uncertainty in whether the SNPs functioned merely as markers or were the direct causants of the cancers.
These varied effects occur due to the different interactions between the SNPs in this region and MYC promoters of different organs. The MYC promoter, which is located at a short distance downstream of the 8q24 region, is perhaps the most studied oncogene due to its association with a myriad of diseases. Normal functioning of the MYC promoter ensures that cells divide regularly. The study postulates that the 8q region, which underwent a chromosomal translocation in humans, could have moved an essential enhancer for the MYC promoter. This areas around this region could have been subjected to recombination that may have hidden the essential MYC enhancer within the gene desert through time, although its enhancing effects are still very much retained. This analysis stems from disease associations observed in several mice species where this region is retained at proximity to the MYC promoter. Thus, the 8q24 gene desert should have been somewhat linked to the MYC promoter. The desert resembles a stable gene desert that has had very little recombination after the translocation event. Thus, a potential hypothesis is that SNPs affecting this region disrupt the important tissue-specific genes with the stable gene desert, which could explain the risks of cancer in various tissue forms. This effect of hidden enhancer elements can also be observed in other locations in the genome. For instance, SNPs in the 5p13.1 deregulate the PTGER4 coding region, leading to Crohn's Disease. Another affected region in the 9p21 gene desert causes several coronary artery diseases. However, none of these risk-conferring gene deserts seem to be affected as much as the 8q24 regions. Current studies are still unsure about the SNP-affected processes in the 8q24 region that result in particularly amplified responses to the MYC promoter. With the aid of a more accessible population and more specific markers for genome wide association mapping, an increasing number of risk alleles are now being marked in gene deserts, where small, isolated, and seemingly-unimportant regions of genes may moderate important genes. | 1 | Gene expression + Signal Transduction |
C-type lectin-like receptors (CLRs) contain one or more C-type lectin (Ca2+ dependent carbohydrate-binding lectin) domains. Example pairs include:
* CD94/NKG2, expressed in NK and some T cells and interacts with the ligand HLA-E.
* Dendritic cell immunoreceptor (DCIR)/dendritic cell immunoactivating receptor (DCAR), characterized as a pair in mice, though no human DCAR has been identified.
* NKR-P1 (CD161) is a member of a paired receptor group in rodents, but the human genome contains only one, inhibitory receptor, NKRP1A (KLRB1).
* The Ly49 family in mice has been extensively studied for its role in NK activation using laboratory mice as a model organism, but has no homologous gene cluster in the human genome. The KIR family is the functional equivalent. | 1 | Gene expression + Signal Transduction |
Utilitarian and ceremonial objects; objects of personal adornment
#Chichén Itzá, Yucatán
#Dzantún C’hen, Yucatán
#Mayapán, Yucatán | 0 | Metallurgy |
ppGpp directly inhibits transcription from ribosomal promoters. One model is ppGpp and DksA together and independently decrease the stability of the open complexes formed on DNA by RNAP. Another model is the trapping mechanism. In this model, RNAP is trapped by ppGpp in closed complexes and is unable to initiate transcription. Thus, ppGpp seems to act at many levels, and the mechanism of its action is a complex outcome of several factors, intrinsic promoter properties not being the least of them. The transcription activation by ppGpp can be direct or indirect. Direct activation occurs when RNAP interacts with effectors, such as ppGpp, DksA or both, to increase transcription from a given promoter. Indirect activation by these effectors of one promoter relies on inhibition of other (strong) promoters, leading to increased availability of RNAP that indirectly activates transcription initiation. The promoters that activated directly by ppGpp include PargI, PthrABC, PlivJ, and PhisG. The indirectly activation promoters include these dependent on sigma factors: S, H, N, E. When strong promoters, such as rrn, are inhibited, there more RNAP are available for these alternative sigma factors. | 1 | Gene expression + Signal Transduction |
The ERK1/2 pathway of mammals is probably the best-characterized MAPK system. The most important upstream activators of this pathway are the Raf proteins (A-Raf, B-Raf or c-Raf), the key mediators of response to growth factors (EGF, FGF, PDGF, etc.); but other MAP3Ks such as c-Mos and Tpl2/Cot can also play the same role. All these enzymes phosphorylate and thus activate the MKK1 and/or MKK2 kinases, that are highly specific activators for ERK1 and ERK2. The latter phosphorylate a number of substrates important for cell proliferation, cell cycle progression, cell division and differentiation (RSK kinases, Elk-1 transcription factor, etc.)
In contrast to the relatively well-insulated ERK1/2 pathway, mammalian p38 and JNK kinases have most of their activators shared at the MAP3K level (MEKK1, MEKK4, ASK1, TAK1, MLK3, TAOK1, etc.). In addition, some MAP2K enzymes may activate both p38 and JNK (MKK4), while others are more specific for either JNK (MKK7) or p38 (MKK3 and MKK6). Due to these interlocks, there are very few if any stimuli that can elicit JNK activation without simultaneously activating p38 or reversed. Both JNK and p38 signaling pathways are responsive to stress stimuli, such as cytokines, ultraviolet irradiation, heat shock, and osmotic shock, and are involved in adaptation to stress, apoptosis or cell differentiation. JNKs have a number of dedicated substrates that only they can phosphorylate (c-Jun, NFAT4, etc.), while p38s also have some unique targets (e.g. the MAPKAP kinases MK2 and MK3), ensuring the need for both in order to respond to stressful stimuli.
ERK5 is part of a fairly well-separated pathway in mammals. Its sole specific upstream activator MKK5 is turned on in response to the MAP3 kinases MEKK2 and MEKK3. The specificity of these interactions are provided by the unique architecture of MKK5 and MEKK2/3, both containing N-terminal PB1 domains, enabling direct heterodimerisation with each other. The PB1 domain of MKK5 also contributes to the ERK5-MKK5 interaction: it provides a special interface (in addition to the D-motif found in MKK5) through which MKK5 can specifically recognize its substrate ERK5. Although the molecular-level details are poorly known, MEKK2 and MEKK3 respond to certain developmental cues to direct endothel formation and cardiac morphogenesis. While also implicated in brain development, the embryonic lethality of ERK5 inactivation due to cardiac abnormalities underlines its central role in mammalian vasculogenesis. It is notable, that conditional knockout of ERK5 in adult animals is also lethal, due to the widespread disruption of endothelial barriers. Mutations in the upstream components of the ERK5 pathway (the CCM complex) are thought to underlie cerebral cavernous malformations in humans. | 1 | Gene expression + Signal Transduction |
When used as a fully supported roof covering, copper is half the weight (including substrate) of lead and only a quarter of tiled roofs. This generally provides savings in supporting structure and materials costs. Copper cladding offers additional opportunities to reduce the weight of copper structures (For more details, see: Copper cladding and Wall cladding). | 0 | Metallurgy |
CCL7 is expressed in many types of cells, including stromal cells, keratinocytes, airway smooth muscle cells, parenchymal cells, fibroblasts and leukocytes and also in tumor cells.
CCL7 mainly acts as a chemoattractant for several leukocytes, including monocytes, eosinophils, basophils, dendritic cells (DCs), neutrophils, NK cells and activated T lymphocytes. Thus, chemotactic factor CCL7 recruits leukocytes to infected tissues to mediate the immune response. Furthermore, CCL7 has an influence to diapedesis and extravasation of leukocytes. The positive effect of CCL7 is mainly observed in monocyte mobilization from bone marrow to blood circulation and in the recruitment of monocytes to sites of inflammation. It was also reported, that CCL7 can also induce neutrophil migration to the inflammatory site by increasing intracellular Ca2+ flux, which is more typical for the CXC chemokine family members.
The speed of immune responses varies depending on the type of the cells. In epithelial cells, fibroblasts, and endothelial cells the response is immediate after the stimulation by proinflammatory cytokines as IL-1β and TNFα. In T lymphocytes the expression of CCL7 occurs after 3–5 days after the stimulation.
CCL7 has been shown to interact with MMP2 by binding CCR2 receptor. | 1 | Gene expression + Signal Transduction |
"TGF" (Transforming Growth Factor) is a family of proteins that includes 33 members that encode dimeric, secreted polypeptides that regulate development. Many developmental processes are under its control including gastrulation, axis symmetry of the body, organ morphogenesis, and tissue homeostasis in adults. All TGF-β ligands bind to either Type I or Type II receptors, to create heterotetramic complexes. | 1 | Gene expression + Signal Transduction |
In metallurgy, exfoliation corrosion (also called lamellar corrosion) is a severe type of intergranular corrosion that raises surface grains from metal by forming corrosion products at grain boundaries under the surface. It is frequently found on extruded sections where grain thickness is not as thick as the rolled grain. It can affect aircraft structures, marine vessels, heaters and other objects. | 0 | Metallurgy |
Genetic mutations occur when nucleotide sequences in an organism are altered. These mutations lead to not only observable phenotypic influences in an individual, but also alterations that are undetectable phenotypically. The sources for these mutations can be errors during replication, spontaneous mutations, and chemical and physical mutagens (UV and ionizing radiation, heat). Silencers, being encoded in the genome, are susceptible to such alterations which, in many cases, can lead to severe phenotypical and functional abnormalities. In general terms, mutations in silencer elements or regions could lead to either the inhibition of the silencers action or to the persisting repression of a necessary gene. This can then lead to the expression or suppression of an undesired phenotype which may affect the normal functionality of certain systems in the organism. Among the many silencer elements and proteins, REST/NSRF is an important silencer factor that has a variety of impacts, not only in neural aspects of development. In fact, in many cases, REST/NSRF acts in conjunction with RE-1/NRSE to repress and influence non-neuronal cells. Its effects range from frogs (Xenopus laevis) to humans, with innumerous effects in phenotype and also in development. In Xenopus laevis, REST/NRSF malfunction or damage has been associated to abnormal ectodermal patterning during development and significant consequences in neural tube, cranial ganglia, and eye development. In humans, a deficiency in the REST/NSRF silencer element has been correlated to Huntingtons disease due to the decrease in the transcription of BDNF.
Furthermore, ongoing studies indicate that NRSE is involved in the regulation of the ANP gene, which when over expressed, can lead to ventricular hypertrophy. Mutations in the Polycomb-group (PcG) complexes also presented significant modifications in physiological systems of organisms. Hence, modification in silencer elements and sequences can result in either devastating or unnoticeable changes. | 1 | Gene expression + Signal Transduction |
Subsets and Splits