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The global steel industry has been going through major changes since 1970. China has emerged as a major producer and consumer, as has India to a lesser extent. Consolidation has been rapid in Europe. According to the 2019 International Energy Agency (IEA) report, the iron and steel industry directly contributed 2.6 Gt to global CO emissions and accounted for 7% of global energy demand. Singapore is the worlds main trading hub for iron, with about 90% of the worlds iron ore derivatives traded on their stock exchange. | 0 | Metallurgy |
While a universally accepted definition of sustainability remains elusive, the Brundtland Commission of the United Nations defined sustainable development as development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Sustainability, the long-term maintenance of responsibility, requires the reconciliation of environmental, social equity and economic demands. These "three pillars" of sustainability encompass the responsible management of resource use. Also, it can mean that we can use a resource which won't cease to be abundant despite increasing intake.
Copper is a sustainable material. Its durability offers long service with little maintenance. Its high electrical and thermal energy efficiencies reduce the waste of electrical energy. Its antimicrobial properties destroy pathogenic microorganisms that cause disease. And its high scrap value and ability to be continuously recycled without any loss in performance ensure its responsible management as a valuable resource.
Life cycle inventory (LCI) information on copper tube, sheet, and wire products, using ISO standards and covering the mining and primary copper production sectors (i.e., smelting and refining) is available. Used in life cycle assessments (LCAs), particularly in the building and construction sector, LCI datasets assist manufacturers of copper-containing products with compliance and voluntary improvement initiatives. They also support policy makers in the development of environmental guidelines and regulations with the aim of fostering sustainable development.
The long lifetime of copper roofing and cladding has a significant positive effect on whole life assessments of copper versus other materials in terms of embodied energy consumption (i.e., the total energy consumed during every phase of each lifecycle in MJ/m), CO generation, and cost. | 0 | Metallurgy |
Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys.
Metallurgy encompasses both the science and the technology of metals, including the production of metals and the engineering of metal components used in products for both consumers and manufacturers. Metallurgy is distinct from the craft of metalworking. Metalworking relies on metallurgy in a similar manner to how medicine relies on medical science for technical advancement. A specialist practitioner of metallurgy is known as a metallurgist.
The science of metallurgy is further subdivided into two broad categories: chemical metallurgy and physical metallurgy. Chemical metallurgy is chiefly concerned with the reduction and oxidation of metals, and the chemical performance of metals. Subjects of study in chemical metallurgy include mineral processing, the extraction of metals, thermodynamics, electrochemistry, and chemical degradation (corrosion). In contrast, physical metallurgy focuses on the mechanical properties of metals, the physical properties of metals, and the physical performance of metals. Topics studied in physical metallurgy include crystallography, material characterization, mechanical metallurgy, phase transformations, and failure mechanisms.
Historically, metallurgy has predominately focused on the production of metals. Metal production begins with the processing of ores to extract the metal, and includes the mixture of metals to make alloys. Metal alloys are often a blend of at least two different metallic elements. However, non-metallic elements are often added to alloys in order to achieve properties suitable for an application. The study of metal production is subdivided into ferrous metallurgy (also known as black metallurgy) and non-ferrous metallurgy, also known as colored metallurgy.
Ferrous metallurgy involves processes and alloys based on iron, while non-ferrous metallurgy involves processes and alloys based on other metals. The production of ferrous metals accounts for 95% of world metal production.
Modern metallurgists work in both emerging and traditional areas as part of an interdisciplinary team alongside material scientists and other engineers. Some traditional areas include mineral processing, metal production, heat treatment, failure analysis, and the joining of metals (including welding, brazing, and soldering). Emerging areas for metallurgists include nanotechnology, superconductors, composites, biomedical materials, electronic materials (semiconductors) and surface engineering. Many applications, practices, and devices associated or involved in metallurgy were established in ancient India and China, such as the innovation of the wootz steel , bronze, blast furnace, cast iron, hydraulic-powered trip hammers, and double acting piston bellows. | 0 | Metallurgy |
*Class I ARE elements, like the c-fos gene, have dispersed AUUUA motifs within or near U-rich regions.
*Class II elements, like the GM-CSF gene, have overlapping AUUUA motifs within or near U-rich regions.
*Class III elements, like the c-jun gene, are a much less well-defined class—they have a U-rich region but no AUUUA repeats.
No real ARE consensus sequence has been determined yet, and these categories are based neither on the same biological functions, nor on the homologous proteins. | 1 | Gene expression + Signal Transduction |
The visual cycle is a circular enzymatic pathway, which is the front-end of phototransduction. It regenerates 11-cis-retinal. For example, the visual cycle of mammalian rod cells is as follows:
#all-trans-retinyl ester + HO → 11-cis-retinol + fatty acid; RPE65 isomerohydrolases;
#11-cis-retinol + NAD → 11-cis-retinal + NADH + H; 11-cis-retinol dehydrogenases;
#11-cis-retinal + aporhodopsin → rhodopsin + HO; forms Schiff base linkage to lysine, -CH=NH-;
#rhodopsin + hν → metarhodopsin II (i.e., 11-cis photoisomerizes to all-trans):
#:(rhodopsin + hν → photorhodopsin → bathorhodopsin → lumirhodopsin → metarhodopsin I → metarhodopsin II);
#metarhodopsin II + HO → aporhodopsin + all-trans-retinal;
#all-trans-retinal + NADPH + H → all-trans-retinol + NADP; all-trans-retinol dehydrogenases;
#all-trans-retinol + fatty acid → all-trans-retinyl ester + HO; lecithin retinol acyltransferases (LRATs).
Steps 3, 4, 5, and 6 occur in rod cell outer segments; Steps 1, 2, and 7 occur in retinal pigment epithelium (RPE) cells.
RPE65 isomerohydrolases are homologous with beta-carotene monooxygenases; the homologous ninaB enzyme in Drosophila has both retinal-forming carotenoid-oxygenase activity and all-trans to 11-cis isomerase activity. | 1 | Gene expression + Signal Transduction |
The archaeological record in Egypt, Peru and the Caucasus suggests that arsenical bronze was produced for a time alongside tin bronze. At Tepe Yahya its use continued into the Iron Age for the manufacture of trinkets and decorative objects, thus demonstrating that there was not a simple succession of alloys over time, with superior new alloys replacing older ones. There are few real advantages metallurgically for the superiority of tin bronze, and early authors suggested that arsenical bronze was phased out due to its health effects. It is more likely that it was phased out in general use because alloying with tin gave castings which had similar strength to arsenical bronze but did not require further work-hardening to achieve useful strength. It is also probable that more certain results could be achieved with the use of tin, because it could be added directly to the copper in specific amounts, whereas the precise amount of arsenic being added was much harder to gauge due to the manufacturing process. | 0 | Metallurgy |
Poly(A)polymerase was first identified in 1960 as an enzymatic activity in extracts made from cell nuclei that could polymerise ATP, but not ADP, into polyadenine. Although identified in many types of cells, this activity had no known function until 1971, when poly(A) sequences were found in mRNAs. The only function of these sequences was thought at first to be protection of the 3′ end of the RNA from nucleases, but later the specific roles of polyadenylation in nuclear export and translation were identified. The polymerases responsible for polyadenylation were first purified and characterized in the 1960s and 1970s, but the large number of accessory proteins that control this process were discovered only in the early 1990s. | 1 | Gene expression + Signal Transduction |
DNA binding trans-acting factors regulate gene expression by interfering with the gene itself or cis-acting elements of the gene, which lead to changes in transcription activities. This can be direct initiation of transcription, promotion, or repression of transcriptional protein activities.
Specific examples include:
* Transcription factors | 1 | Gene expression + Signal Transduction |
The most common mammalian expression systems are Chinese Hamster ovary (CHO) and Human embryonic kidney (HEK) cells.
* Chinese hamster ovary cell
* Mouse myeloma lymphoblstoid (e.g. NS0 cell)
* Fully Human
** Human embryonic kidney cells (HEK-293)
** Human embryonic retinal cells (Crucell's Per.C6)
** Human amniocyte cells (Glycotope and CEVEC) | 1 | Gene expression + Signal Transduction |
The human TRiC complex is formed by two rings containing 8 similar but non-identical subunits, each with molecular weights of ~60 kDa. The two rings are stacked in an asymmetrical fashion, forming a barrel-like structure with a molecular weight of ~1 MDa.
Molecular weight of human subunits.
Counterclockwise from the exterior, each ring is made of the subunits in the following order: 6-8-7-5-2-4-1-3. | 1 | Gene expression + Signal Transduction |
There are two defects in this category: hot tears and hot spots. Hot tears, also known as , are failures in the casting that occur as the casting cools. This happens because the metal is weak when it is hot and the residual stresses in the material can cause the casting to fail as it cools. Proper mould design prevents this type of defect.
Hot spots are sections of casting which have cooled down more slowly than the surrounding material due to higher volume than its surrounding. This causes abnormal shrinkage in this region, which can lead to porosity and cracks. This type of defect can be avoided by proper cooling practices or by changing the chemical composition of the metal.
Additional methods of minimising hot tears are not overheating the casting material and increasing the temperature of the mould. | 0 | Metallurgy |
Casein kinase activity was found to be present in most cell types and to be associated with multiple enzymes. The type 1 casein kinase family of related gene products are now given designations such as "casein kinase 1 alpha" and "casein kinase 1 epsilon". | 1 | Gene expression + Signal Transduction |
RNA activation (RNAa) is a small RNA-guided and Argonaute (Ago)-dependent gene regulation phenomenon in which promoter-targeted short double-stranded RNAs (dsRNAs) induce target gene expression at the transcriptional/epigenetic level. RNAa was first reported in a 2006 PNAS paper by Li et al. who also coined the term "RNAa" as a contrast to RNA interference (RNAi) to describe such gene activation phenomenon. dsRNAs that trigger RNAa have been termed small activating RNA (saRNA). Since the initial discovery of RNAa in human cells, many other groups have made similar observations in different mammalian species including human, non-human primates, rat and mice, plant and C. elegans, suggesting that RNAa is an evolutionarily conserved mechanism of gene regulation.
RNAa can be generally classified into two categories: exogenous and endogenous. Exogenous RNAa is triggered by artificially designed saRNAs which target non-coding sequences such as the promoter and the 3’ terminus of a gene and these saRNAs can be chemically synthesized or expressed as short hairpin RNA (shRNA). Whereas for endogenous RNAa, upregulation of gene expression is guided by naturally occurring endogenous small RNAs such as miRNA in mammalian cells and C. elegans, and 22G RNA in C. elegans. | 1 | Gene expression + Signal Transduction |
DNA editing proteins edit and permanently change gene sequence, and subsequently the gene expression of the cell. All progenies of the cell will inherit the edited gene sequence. DNA editing proteins often take part in the immune response system of both prokaryotes and eukaryotes, providing high variance in gene expression in adaptation to various pathogens.
Specific examples include:
* RAG1/RAG2
* TdT
* Cas1/Cas2 | 1 | Gene expression + Signal Transduction |
SFRS1 is a proto-oncogene, and thus ASF/SF2 can act as an oncoprotein; it can alter the splicing patterns of crucial cell cycle regulatory genes and suppressor genes. ASF/SF2 controls the splicing of various tumor suppressor genes, kinases, and kinase receptors, all of which have the potential to be alternatively spliced into oncogenic isoforms. As such, ASF/SF2 is an important target for cancer therapy, as it is over-expressed in many tumors.
Modifications and defects in the alternative splicing pathway are associated with a variety of human diseases.
ASF/SF2 is involved in the replication of HIV-1, as HIV-1 needs a delicate balance of spliced and unspliced forms of its viral DNA. ASF/SF2 action in the replication of HIV-1 is a potential target for HIV therapy. ASF/SF2 is also implicated in the production of T cell receptors in Systemic Lupus Erythematosus, altering specific chain expression in T cell receptors through alternative splicing. | 1 | Gene expression + Signal Transduction |
In the 19th century, a number of people had employed an electric arc to melt iron. Sir Humphry Davy conducted an experimental demonstration in 1810; welding was investigated by Pepys in 1815; Pinchon attempted to create an electrothermic furnace in 1853; and, in 1878–79, Sir William Siemens took out patents for electric furnaces of the arc type.
The first successful and operational furnace was invented by James Burgess Readman in Edinburgh, Scotland, in 1888 and patented in 1889. This was specifically for the creation of phosphorus.
Further electric arc furnaces were developed by Paul Héroult, of France, with a commercial plant established in the United States in 1907. The Sanderson brothers formed The Sanderson Brothers Steel Co. in Syracuse, New York, installing the first electric arc furnace in the U.S. This furnace is now on display at Station Square, Pittsburgh, Pennsylvania.
Initially "electric steel" produced by an electric arc furnace was a specialty product for such uses as machine tools and spring steel. Arc furnaces were also used to prepare calcium carbide for use in carbide lamps. The Stassano electric furnace is an arc type furnace that usually rotates to mix the bath. The Girod furnace is similar to the Héroult furnace.
While EAFs were widely used in World War II for production of alloy steels, it was only later that electric steelmaking began to expand. The low capital cost for a mini-mill—around US$140–200 per ton of annual installed capacity, compared with US$1,000 per ton of annual installed capacity for an integrated steel mill—allowed mills to be quickly established in war-ravaged Europe, and also allowed them to successfully compete with the big United States steelmakers, such as Bethlehem Steel and U.S. Steel, for low-cost, carbon steel "long products" (structural steel, rod and bar, wire, and fasteners) in the U.S. market.
When Nucor—now one of the largest steel producers in the US — entered the market for long steel products in 1969, they used a mini-mill with an EAF as its steelmaking furnace, soon followed by other manufacturers. Whilst Nucor expanded rapidly in the Eastern US, the companies that followed them into mini-mill operations concentrated on local markets for long products, where the EAF allowed the plants to vary production according to local demand. This pattern was followed globally, with EAF steel production primarily used for long products, while integrated mills, using blast furnaces and basic oxygen furnaces, cornered the markets for "flat products"—sheet steel and heavier steel plate. In 1987, Nucor expanded into the flat products market, still using the EAF production method. | 0 | Metallurgy |
The ore to be treated is ground into particles (comminution). In the idealized case, the individual minerals are physically separated, a process known as full liberation. The particle sizes are typically in the range 2–500 micrometers in diameter. For froth flotation, an aqueous slurry of the ground ore is treated with the frothing agent. An example is sodium ethyl xanthate as a collector in the flotation of galena (lead sulfide) to separate it from sphalerite (zinc sulfide). The polar part of xanthate anion attaches to the ore particles and the non-polar hydrocarbon part forms a hydrophobic layer. The particles are brought to the water surface by air bubbles. About 300 g/t of ore is required for efficient separation. With increasing length of the hydrocarbon chain in xanthates, the efficiency of the hydrophobic action increases, but the selectivity to ore type decreases. The chain is shortest in sodium ethyl xanthate that makes it highly selective to copper, nickel, lead, gold, and zinc ores. Aqueous solutions (10%) with pH = 7–11 are normally used in the process. This slurry (more properly called the pulp) of hydrophobic particles and hydrophilic particles is then introduced to tanks known as flotation cells that are aerated to produce bubbles. The hydrophobic particles attach to the air bubbles, which rise to the surface, forming a froth. The froth is skimmed from the cell, producing a concentrate ("conc") of the target mineral.
The minerals that do not float into the froth are referred to as the flotation tailings or flotation tails. These tailings may also be subjected to further stages of flotation to recover the valuable particles that did not float the first time. This is known as scavenging. The final tailings after scavenging are normally pumped for disposal as mine fill or to tailings disposal facilities for long-term storage.
Flotation is normally undertaken in several stages to maximize the recovery of the target mineral or minerals and the concentration of those minerals in the concentrate, while minimizing the energy input. | 0 | Metallurgy |
The phenomenon of electroluminescence was discovered in 1907 using silicon carbide and the first commercial LEDs were based on SiC. Yellow LEDs made from 3C-SiC were manufactured in the Soviet Union in the 1970s and blue LEDs (6H-SiC) worldwide in the 1980s.
Carbide LED production soon stopped when a different material, gallium nitride, showed 10–100 times brighter emission. This difference in efficiency is due to the unfavorable indirect bandgap of SiC, whereas GaN has a direct bandgap which favors light emission. However, SiC is still one of the important LED components: It is a popular substrate for growing GaN devices, and it also serves as a heat spreader in high-power LEDs. | 0 | Metallurgy |
The European Coil Coating Association (ECCA) is an international non-profit association dedicated to the diffusion of the use of coil and/or sheet coated metal. | 0 | Metallurgy |
Wootz is characterized by a pattern caused by bands of clustered particles made by melting of low levels of carbide-forming elements. Wootz contains greater carbonaceous matter than common qualities of cast steel.
The distinct patterns of Wootz steel that can be made through forging are wave, ladder, and rose patterns with finely spaced bands. However, with hammering, dyeing, and etching further customized patterns were made.
The presence of cementite nanowires and carbon nanotubes has been identified by Peter Pepler of TU Dresden in the microstructure of wootz steel. There is a possibility of an abundance of ultrahard metallic carbides in the steel matrix precipitating out in bands.Wootz swords were renowned for their sharpness and toughness. | 0 | Metallurgy |
Live cell imaging and proteomic studies have allowed researchers at the centre to gain fresh understanding of protein function and cell behaviour.
The centre is studying many aspects of the cell cycle, including the way in which chromosomes replicate and separate during cell division and how DNA damage is detected. Failure of these events can lead to major faults within a genome, potentially leading to the rise of cancerous cells. The centre is also investigating how DNA is tightly wound and compacted so that it can fit into the nuclei of eukaryotic cells, as well as the protein-DNA complexes that are involved in this packaging. The controlled unravelling of DNA is an important step in the regulation of gene function. | 1 | Gene expression + Signal Transduction |
A single conductive wire is used as feedstock for the system. A supersonic plasma jet—formed by a transferred arc between a non-consumable cathode and the wire—melts and atomizes the wire. A stream of air transports the atomized metal onto the substrate. The particles flatten upon striking the surface of the substrate due to their high kinetic energy. The particles rapidly solidify upon contact and can assume both crystalline and amorphous phases. There is also the possibility of producing multi-layer coatings via stacked layers of particles, increasing wear resistance. All conductive wires up to and including can be used as feedstock material, including "cored" wires. Refractory metals, as well as low melt materials, are easily deposited. | 0 | Metallurgy |
Control of the process of gene transcription affects patterns of gene expression and, thereby, allows a cell to adapt to a changing environment, perform specialized roles within an organism, and maintain basic metabolic processes necessary for survival. Therefore, it is hardly surprising that the activity of RNAP is long, complex, and highly regulated. In Escherichia coli bacteria, more than 100 transcription factors have been identified, which modify the activity of RNAP.
RNAP can initiate transcription at specific DNA sequences known as promoters. It then produces an RNA chain, which is complementary to the template DNA strand. The process of adding nucleotides to the RNA strand is known as elongation; in eukaryotes, RNAP can build chains as long as 2.4 million nucleotides (the full length of the dystrophin gene). RNAP will preferentially release its RNA transcript at specific DNA sequences encoded at the end of genes, which are known as terminators.
Products of RNAP include:
* Messenger RNA (mRNA)—template for the synthesis of proteins by ribosomes.
* Non-coding RNA or "RNA genes"—a broad class of genes that encode RNA that is not translated into protein. The most prominent examples of RNA genes are transfer RNA (tRNA) and ribosomal RNA (rRNA), both of which are involved in the process of translation. However, since the late 1990s, many new RNA genes have been found, and thus RNA genes may play a much more significant role than previously thought.
** Transfer RNA (tRNA)—transfers specific amino acids to growing polypeptide chains at the ribosomal site of protein synthesis during translation
** Ribosomal RNA (rRNA)—a component of ribosomes
** Micro RNA—regulates gene activity
** Catalytic RNA (Ribozyme)—enzymatically active RNA molecules
RNAP accomplishes de novo synthesis. It is able to do this because specific interactions with the initiating nucleotide hold RNAP rigidly in place, facilitating chemical attack on the incoming nucleotide. Such specific interactions explain why RNAP prefers to start transcripts with ATP (followed by GTP, UTP, and then CTP). In contrast to DNA polymerase, RNAP includes helicase activity, therefore no separate enzyme is needed to unwind DNA. | 1 | Gene expression + Signal Transduction |
RNA molecules that do not code for any proteins still maintain a function in the cell. The function of the RNA depends on its classification. These roles include:
* aiding protein synthesis
* catalyzing reactions
* regulating various processes.
Protein synthesis is aided by functional RNA molecules such as tRNA, which helps add the correct amino acid to a polypeptide chain during translation, rRNA, a major component of ribosomes (which guide protein synthesis), as well as mRNA which carry the instructions for creating the protein product.
One type of functional RNA involved in regulation are microRNA (miRNA), which works by repressing translation. These miRNAs work by binding to a complementary target mRNA sequence to prevent translation from occurring. Short-interfering RNA (siRNA) also work by negative regulation of transcription. These siRNA molecules work in RNA-induced silencing complex (RISC) during RNA interference by binding to a target DNA sequence to prevent transcription of a specific mRNA. | 1 | Gene expression + Signal Transduction |
Cupellation was also being used in parts of Europe to extract gold, silver, zinc, and tin by the late ninth to tenth century AD. Here, one of the earliest examples of an integrated unit process for extracting more than one precious metal was first introduced by Theophilus around the twelfth century. First, the gold-silver ore is melted down in the crucible, but with an excess amount of lead. The intense heat then oxidizes the lead which reacts quickly and binds with the impurities in the gold-silver ore. Since both gold and silver have low reactivity with the impurities, they remain behind once the slag is removed. The last stage involves parting, in which the silver is separated from the gold. First the gold-silver alloy is hammered into thin sheets and placed into a vessel. The sheets were then covered in urine, which contains sodium chloride (NaCl). The vessel is then capped and heated for several hours until the chlorides bind with the silver, creating silver chloride (AgCl). Finally, the silver chloride powder is then removed and smelted to recover the silver, while the pure gold remains intact. | 0 | Metallurgy |
AR STAT2 deficiency was first time observed in 2 siblings. After routine immunization with measles-mump-rubella, one sibling developed disseminated vaccine-strain measles (MMR) but recovered and second sibling died in infancy from a viral infection due to primary immunodeficiency disorder. Later, the results showed that siblings were homozygous for absent expression of gene for STAT2. Patients with AR STAT2 deficiency have mutations which bring substitutions at important splice sites what leads to defected splicing and premature stop codons leading to a loss of expression of an interferon-stimulated gene. The typical clinical phenotype is disseminated infection after immunization with the live attenuated MMR vaccine. Some patients had also an onset of severe disease in infancy like infection with RSV, norovirus, coxsackievirus, adenovirus or enterovirus. One of the patients had CNS disease after the primary infection with EBV. EBV suppression was delayed in peripheral blood and cerebrospinal fluid as type I interferon signalling plays important role in the initial immune response against EBV. During next 3 years, PCR test showed persistent EBV presence in blood as well as in cerebrospinal fluid despite anti-EBV IgG. CMV and VZV infections were severe as well in few patients. The virus infection was treated by high-dose of intravenous immunoglobulin (IVIG) after which patients recovered and became afebrile within 24 hours. IVIG has anti-inflammatory effect and suggests that the passive immunization could help to control the ongoing viral infections. Therefore, the monthly IgG therapy could be beneficial for patients with STAT2 deficiency during childhood, until their adaptive immune system has sufficiently developed. From the age 5 years, the frequency and severity of viral infections decreased and the age of 10 years the patients were mostly off all medication. In general, the patients with STAT2 deficiency are relatively healthy with no specific defects in their adaptive immunity or developmental abnormalities. These findings show that type I IFN signaling trough ISGF3 is not essential for host defense against the majority of common childhood viral pathogens. Despite a profoundly defective innate IFN response and evident susceptibility to some viral infections, STAT2-deficient individuals can live a relatively healthy life.
It was also reported a homozygous STAT2 missense mutation (R148W/Q) which results to a STAT2 gain of function underlying fatal early-onset autoinflammation in three patients. This mutation leads to a persistent type I IFN response due to defective binding of the mutated STAT2 to ubiquitin specific peptidase 1 (USP18) which is an essential in the negative autofeedback loop where USP18 sterically hinders the binding of JAK1 to IFNAR1. Therefore complete AR STAT2 deficiency usually causes disseminated LAV infection and recurrent natural viral infections. Penetrance is not complete for several viral infections and for complicated live measles vaccine disease. These observation suggest that the phenotype of AR STAT2 deficiency could range from asymptomatic (the healthy adult) to fatal (childhood death from a crushing viral disease). The phenotype is less severe than human complete AR STAT1 deficiency but more severe than IFNAR1 or IFNAR2 deficiency. The human phenotype is less severe than in mice. | 1 | Gene expression + Signal Transduction |
Abrasive blasting also known as sandblasting, involves using compressed air to fire a steam of clean, sharp, crushed steel grit or aluminum oxide onto the surface of the component. Aluminum is a good option as it is relatively cheap. The fired grit breaks off small chucks of the substrate surface creating an evenly rough surface for good mechanical bonds to form. The substrate needs to be cleaned of any debris and residual grit from blasting prior to spraying. | 0 | Metallurgy |
Ethnoarchaeology has been widely used in conjunction with experimental archaeology using the techniques of modern peoples as analogues to the processes of the past. The attempted use of ethnology in archaeology tries to counteract the cultural distance of the researcher from process by changing the context of experimentation. Africa has played a large role in reconstructing copper smelting and bloomery iron furnaces as there are still several places that practice a workshop production of iron. Killick has been one such archaeologist to utilize surviving iron production in Africa to gain further insight into how other furnaces from around the world may have been constructed. | 0 | Metallurgy |
In molecular genetics, a regulon is a group of genes that are regulated as a unit, generally controlled by the same regulatory gene that expresses a protein acting as a repressor or activator. This terminology is generally, although not exclusively, used in reference to prokaryotes, whose genomes are often organized into operons; the genes contained within a regulon are usually organized into more than one operon at disparate locations on the chromosome. Applied to eukaryotes, the term refers to any group of non-contiguous genes controlled by the same regulatory gene.
A modulon is a set of regulons or operons that are collectively regulated in response to changes in overall conditions or stresses, but may be under the control of different or overlapping regulatory molecules. The term stimulon is sometimes used to refer to the set of genes whose expression responds to specific environmental stimuli. | 1 | Gene expression + Signal Transduction |
Heating white cast iron (containing iron carbide, i.e. cementite, but no uncombined carbon) above causes the formation of austenite in crystals of primary cementite. This austenisation of white iron occurs in primary cementite at the interphase boundary with ferrite. When the grains of austenite form in cementite, they occur as lamellar clusters oriented along the cementite crystal layer surface. Austenite is formed by diffusion of carbon atoms from cementite into ferrite. | 0 | Metallurgy |
The test chamber has a set volume of 300L. The construction of the inner housing of the chamber and the devices for arranging the samples must be made of inert and corrosion-resistant materials so that there is no reaction between the sample to be tested and the material of the chamber. The SO injection can be performed manually or automatically depending on the chamber. | 0 | Metallurgy |
In the late 1800s, with the large investments financed by northern bankers and southern investors, as well as the technological expertise provided by northern and mid-western engineers, the iron and steel industry began to flourish in Birmingham, Alabama. In addition, the growth of Alabamas iron and steel industry was further facilitated by the influx of a large labour force at that time. During the last decades of the nineteenth century, Alabamas agricultural sector was mainly dominated by the economic models of sharecropping and tenant farming. This tenancy system encompassed over 60 percent of the farming population in Alabama; however, under its influence, landless farmers had to suffer from a legacy of illiteracy and poverty. Driven by poverty, many labourers, including unemployed and impoverished freedmen and white people, began to search for jobs in the iron-and-steel manufacturing industry, which was considered to be a more attractive alternative to sharecropping and tenant farming. Moreover, the introduction of convict-lease system also provided Alabamas iron and steel manufacturers with abundant cheap labour. The convict-lease system functioned in the state and counties of Alabama between 1875 and 1928, through which iron manufacturers paid to the local governments in exchange for prison labour. As regulated by the system, prisoners had to work for the companies that leased them from the governments. Until its abolition in 1928, the convict-lease system had provided iron manufacturers, owners of coal mines, and other enterprises in Alabama with a substantial number of prisoners as cheap labourers. At the end of the nineteenth century, due to the regions abundant geographical resources coupled with its low raw-material assembly costs, Alabama experienced a period of rocket development. | 0 | Metallurgy |
In the GeneCalling protocol, mRNAs are first isolated from a given sample and processed into fragments for analysis. This usually involves the synthesis and subdivision of double-stranded cDNAs from polyA RNA. Distinct sets of restriction enzymes can then be used to digest sets of the divided cDNAs and resulting fragments ligated to labelled adapters to be amplified by PCR. PCR products are then purified and subjected to gel electrophoresis on a mounted platform employing stationary laser excitation and a multi-colour charge-coupled device imaging system. A fluorescent label at the 5' end of one of the PCR primers allows for visualization of the PCR fragments, and the cDNAs are subjected to several isolated and identical restriction digests to generate a merged profile based on peak height and variance. The merged digestion profiles from the cDNA preparations are then compared to locate differentially expressed fragments (such as between normal tissue and diseased or drug responsive tissue); these profiles are compared by means of various internet-ready databases such as GeneScape. | 1 | Gene expression + Signal Transduction |
A splice site mutation is a genetic mutation that inserts, deletes or changes a number of nucleotides in the specific site at which splicing takes place during the processing of precursor messenger RNA into mature messenger RNA. Splice site consensus sequences that drive exon recognition are located at the very termini of introns. The deletion of the splicing site results in one or more introns remaining in mature mRNA and may lead to the production of abnormal proteins. When a splice site mutation occurs, the mRNA transcript possesses information from these introns that normally should not be included. Introns are supposed to be removed, while the exons are expressed.
The mutation must occur at the specific site at which intron splicing occurs: within non-coding sites in a gene, directly next to the location of the exon. The mutation can be an insertion, deletion, frameshift, etc. The splicing process itself is controlled by the given sequences, known as splice-donor and splice-acceptor sequences, which surround each exon. Mutations in these sequences may lead to retention of large segments of intronic DNA by the mRNA, or to entire exons being spliced out of the mRNA. These changes could result in production of a nonfunctional protein. An intron is separated from its exon by means of the splice site. Acceptor-site and donor-site relating to the splice sites signal to the spliceosome where the actual cut should be made. These donor sites, or recognition sites, are essential in the processing of mRNA. The average vertebrate gene consists of multiple small exons (average size, 137 nucleotides) separated by introns that are considerably larger. | 1 | Gene expression + Signal Transduction |
Temperature ratings for insulations may vary based on what the overall thermocouple construction cable consists of.
Note: T300 is a new high-temperature material that was recently approved by UL for 300 °C operating temperatures. | 0 | Metallurgy |
Eshelby was elected a Fellow of the Royal Society in March 1974. He was awarded the Timoshenko Medal in 1977.
In 2012, the Eshelby Mechanics Award for Young Faculty and the Eshelby Memorial Bursary was founded in his memory. was launched to commemorate the memory of Eshelby. The award is given annually to rapidly emerging junior faculty who exemplify the creative use and development of mechanics, and awardees are formally recognised at the annual Applied Mechanics Division Banquet at the American Society of Mechanical Engineers' International Mechanical Engineering Congress and Exposition (ASME-IMECE) meeting. | 0 | Metallurgy |
The cAMP response element CREB is closely related to the cell decision to proliferate or not. Cells that are forced to overexpress AKT increase the amount of CREB and proliferation compared to wild type cells. These cells also express less glial and neural cell markers such as GFAP or β-tubulin. This is because CREB is a transcription factor that influences the transcription of cyclin A which promotes proliferation. For example, adult hippocampal neural progenitor cells need abeyance as stem cells to differentiate later. This is regulated by Shh. Shh works through a slow protein synthesis dependence, which stimulates other cascades that work synergistically with the PI3K/AKT pathway to induce proliferation. Then, the other pathway can be turned off and the effects of the PI3K/AKT pathway become insufficient in stopping differentiation. The specifics of this pathway are unknown. | 1 | Gene expression + Signal Transduction |
Al-Si-Cu-Mg alloys form Al5FeSi- plate like intermetallic phases like -Al8Fe2Si, Al2Cu, etc. The size and morphology of these intermetallic phases in these alloys control the mechanical properties of these alloys, especially strength and ductility. The size of these phases depends on the secondary dendrite arm spacing, as well as the Si content of the alloy, of the primary phase in the micro structure. | 0 | Metallurgy |
There are 3 types of tumor suppressor genes:
* Genes that affect cell growth
* Genes that limit the cell cycle and induce apoptosis
* Genes that repair damaged DNA
SFRP1 appears to fall in the first category of genes, those that affect cell growth.
The role of SFRP1 as a tumor suppressor has been proposed in many cancers, based on its loss in patient tumors. Its frequent inactivation by methylation-induced silencing is consistent with it behaving as a tumor suppressor. Also, the SFRP1 gene is located in a region on chromosome 8 that is frequently lost in many cancer types. Expression levels of several targets of the Wnt signaling pathways are increased in tumor tissue compared with normal, and the expression of SFRP1 is lost in patient tumor samples. The role for the Wnt/β-catenin signaling in cancer has been well defined: β-catenin drives transcription of genes that contribute to the tumor phenotype by regulating processes such as proliferation, survival and invasion.
Gumz et al. showed that SFRP1 expression in UMRC3 cells (clear cell renal cell carcinoma cell line) resulted in a growth-inhibited phenotype. SFRP1 expression not only reduced the expression of Wnt target genes, but also markedly inhibited tumor cell growth in culture, soft agar and xenografts in athymic nude mice. Growth in culture and anchorage-independent growth were inhibited in SFRP1-expressing UMRC3 cells. The growth-inhibitory effects of SFRP1 were due primarily to decreased cell proliferation rather than an increase in apoptosis. This was consistent with the effect of SFRP1 on cellular proliferation as seen in prostate cancer, where retroviral-mediated expression of SFRP1 resulted in inhibited cellular proliferation but had no effect on apoptosis. Also, restoration of SFRP1 expression attenuated the malignant phenotype of cRCC; moreover, other studies showed reexpression of SFRP1 resulted in decreased colony formation in colon and lung cancer models. | 1 | Gene expression + Signal Transduction |
*ABCB10 NM_012089
*ABCB7 NM_004299
*ABCD3 NM_002857
*ABCE1 NM_002939
*ABCF1 NM_001090
*ABCF2 NM_005692
*ABCF3 NM_018358
*CALM1 Calmodulin grasps calcium ions
*MFSD11 NM_024311 similar to MSFD10 aka TETRAN or tetracycline transporter-like protein
*MFSD12 NM_174983
*MFSD3 NM_138431
*MFSD5 NM_032889
*SLC15A4 NM_145648
*SLC20A1 NM_005415
*SLC25A11 mitochondrial oxoglutarate/malate carrier
*SLC25A26 NM_173471
*SLC25A28 NM_031212
*SLC25A3 NM_002635
*SLC25A32 NM_030780
*SLC25A38 NM_017875
*SLC25A39 NM_016016
*SLC25A44 NM_014655
*SLC25A46 NM_138773
*SLC25A5 NM_001152
*SLC27A4 NM_005094
*SLC30A1 NM_021194
*SLC30A5 NM_022902
*SLC30A9 NM_006345
*SLC35A2 NM_005660
*SLC35A4 NM_080670
*SLC35B1 NM_005827
*SLC35B2 NM_178148
*SLC35C2 NM_015945
*SLC35E1 NM_024881
*SLC35E3 NM_018656
*SLC35F5 NM_025181
*SLC38A2 NM_018976
*SLC39A1 NM_014437
*SLC39A3 NM_144564
*SLC39A7 NM_006979
*SLC41A3 NM_017836
*SLC46A3 NM_181785
*SLC48A1 NM_017842 | 1 | Gene expression + Signal Transduction |
Because mechanisms that control the accumulation of damage through the lifetime of a cell are essential to longevity, it is logical that caretaker and gatekeeper genes play a significant role in cellular aging. Increased activity of caretaker genes postpones aging, increasing lifespan. This is because of the regulatory function associated with caretaker genes in maintaining the stability of the genome. The actions of caretaker genes contribute to increasing lifespan of the cell.
A specific purpose of caretaker genes has been outlined in chromosomal duplication. Caretakers have been identified as crucial to encoding products that maintain the telomeres. It is believed that degradation of telomeres, the ends of chromosomes, through repeated cell cycle divisions, is a main component of cellular aging and death.
It has been suggested that gatekeeper genes confer beneficial anti-cancer affects but may provide deleterious effects that increase aging. This is because young organisms experiencing times of rapid growth necessitate significant anti-cancer mechanisms. As the organism ages, however, these formerly beneficial pathways become deleterious by inducing apoptosis in cells of renewable tissues, causing degeneration of the structure. Studies have shown an increased expression of pro-apoptotic genes in age-related pathologies. This is because the products of gatekeeper genes are directly involved in coding for cellular growth and proliferation.
However, dysfunctional caretaker genes do not always lead to a cancerous phenotype. For example, defects in nucleotide excision repair pathways are associated with premature aging phenotypes in diseases such as Xeroderma pigmentosum and Trichothiodystrophy. These patients exhibit brittle hair, nails, scaly skin, and hearing loss – characteristics associated with simple human aging. This is important because the nucleotide excision repair pathway is a mechanism thought to be encoded by a caretaker gene. Geneticists studying these premature-aging syndromes propose that caretaker genes that determine cell fate also play a significant role in aging. Accumulation of DNA damage with age may be especially prevalent in the central nervous system because of low DNA repair capability in postmitotic brain tissue.
Similarly, gatekeeper genes have been identified as having a role in aging disorders that exhibit mutations in such genes without an increased susceptibility to cancer. Experiments with mice that have increased gatekeeper function in the p53 gene show reduced cancer incidence (due to the protective activities of products encoded by p53) but a faster rate of aging.
Cellular senescence, also encoded by a gatekeeper gene, is arrest of the cell cycle in the G1 phase. Qualitative differences have been found between senescent cells and normal cells, including differential expression of cytokines and other factors associated with inflammation. It is believed that this may contribute, in part, to cellular aging.
In sum, although mechanisms encoded by gatekeeper and caretaker genes to protect individuals from cancer early in life, namely induction of apoptosis or senescence, later in life these functions may promote the aging phenotype. | 1 | Gene expression + Signal Transduction |
The BioBricks assembly standard was described and introduced by Tom Knight in 2003 and it has been constantly updated since then. Currently, the most commonly used BioBricks standard is the assembly standard 10, or BBF . BioBricks defines the prefix and suffix sequences required for a DNA part to be compatible with the BioBricks assembly method, allowing the joining of all DNA parts which are in the BioBricks format.
The prefix contains the restriction sites for EcoRI, NotI and XBaI, while the suffix contains the SpeI, NotI and PstI restriction sites. Outside of the prefix and suffix regions, the DNA part must not contain these restriction sites. To join two BioBrick parts together, one of the plasmids is digested with EcoRI and SpeI while the second plasmid is digested with EcoRI and XbaI. The two EcoRI overhangs are complementary and will thus anneal together, while SpeI and XbaI also produce complementary overhangs which can also be ligated together. As the resulting plasmid contains the original prefix and suffix sequences, it can be used to join with more BioBricks parts. Because of this property, the BioBricks assembly standard is said to be idempotent in nature. However, there will also be a "scar" sequence (either TACTAG or TACTAGAG) formed between the two fused BioBricks. This prevents BioBricks from being used to create fusion proteins, as the 6bp scar sequence codes for a tyrosine and a stop codon, causing translation to be terminated after the first domain is expressed, while the 8bp scar sequence causes a frameshift, preventing continuous readthrough of the codons. To offer alternative scar sequences that for example give a 6bp scar, or scar sequences that do not contain stop codons, other assembly standards such as the BB-2 Assembly, BglBricks Assembly, Silver Assembly and the Freiburg Assembly were designed.
While the easiest method to assemble BioBrick parts is described above, there also exist several other commonly used assembly methods that offer several advantages over the standard assembly. The 3 antibiotic (3A) assembly allows for the correct assembly to be selected via antibiotic selection, while the amplified insert assembly seeks to overcome the low transformation efficiency seen in 3A assembly.
The BioBrick assembly standard has also served as inspiration for using other types of endonucleases for DNA assembly. For example, both the iBrick standard and the HomeRun vector assembly standards employ homing endonucleases instead of type II restriction enzymes. | 1 | Gene expression + Signal Transduction |
The advent of inexpensive microarray experiments created several specific bioinformatics challenges: the multiple levels of replication in experimental design (Experimental design); the number of platforms and independent groups and data format (Standardization); the statistical treatment of the data (Data analysis); mapping each probe to the mRNA transcript that it measures (Annotation); the sheer volume of data and the ability to share it (Data warehousing). | 1 | Gene expression + Signal Transduction |
In the coreless type, metal is placed in a crucible surrounded by a water-cooled alternating current solenoid coil. A channel-type induction furnace has a loop of molten metal, which forms a single-turn secondary winding through an iron core. | 0 | Metallurgy |
Several metal objects similar to those in the Kfar Monash hoard were found in this general area of the Levant. They were subject to metallurgical analysis, and generally dated to the Early Bronze Age. For example, objects from Ashkelon-Afridar, and from Tell esh-Shuna (the Jordan Valley) were seen as similar. Also the axes from early EB I Yiftah’el are seen as relevant.
Kfar Monash objects were also dated, based on typological considerations, to EB IB, similarly to the axes from Tel Beth Shean.
The study of Kfar Monash hoard indicated that some of them were made of unalloyed copper. The source of this unalloyed copper was found likely to be in Wadi Feynan, in southern Jordan. Such unalloyed copper was apparently mainly used for the production of tools.
Other objects were made using a CuAsNi alloy. This is the copper-arsenic-nickel alloy that is especially characteristic of Chalcolithic period Arslantepe in Eastern Anatolia (the upper Euphrates region). Nevertheless, the adzes that were made of this alloy were determined to be of "an Egyptian type".
Objects from Arslantepe using such polymetallic ores are mainly ascribed to Level VIA (3400–3000 BCE), dating to the Uruk period. | 0 | Metallurgy |
Slow strain rate testing (SSRT), also called constant extension rate tensile testing (CERT), is a popular test used by research scientists to study stress corrosion cracking. It involves a slow (compared to conventional tensile tests) dynamic strain applied at a constant extension rate in the environment of interest. These test results are compared to those for similar tests in a, known to be inert, environment. A 50-year history of the SSRT has recently been published by its creator. The test has also been standardized and two ASTM symposia devoted to it. | 0 | Metallurgy |
CcrM is a type II DNA Methyltransferase, that transfer a methyl group from the methyl donor SAM to the N6 of an adenine in a 5-GANTC-3 recognition sites of hemimethylated DNA. Based on the order of the conserved motifs that form the SAM binding, the active site and the target recognition domain in the sequence of CcrM it can be classified as a β-class adenine N6 Methyltransferase. CcrM homologs in Alphaproteobacteria have an 80 residues C terminal domain, with non well characterized function.
CcrM is characterized by a high degree of sequence discrimination, showing a very high specificity for GANTC sites over AANTC sites , being able to recognize and methylate this sequence in both double and single strand DNA. CcrM in complex with a dsDNA structure was resolved, showing that the enzyme presents a novel DNA interaction mechanism, opening a bubble in the DNA recognition site (The concerted mechanism of Methyltransferases relies in the flip of the target base), the enzyme interacts with DNA forming an homodimer with differential monomer interactions.
CcrM is a highly efficient enzyme capable of methylating a high number of 5-GANTC-3 sites in low time, however if the enzyme is processive (the enzyme binds to the DNA and methylate several methylation sites before dissociation) or distributive (the enzyme dissociates from DNA after each methylation) it is still in discussion. First reports indicated the second case, however more recent characterisation of CcrM indicate that it is a processive enzyme. | 1 | Gene expression + Signal Transduction |
Tin-silver-copper (Sn-Ag-Cu, also known as SAC), is a lead-free (Pb-free) alloy commonly used for electronic solder. It is the main choice for lead-free surface-mount technology (SMT) assembly in the industry, as it is near eutectic, with adequate thermal fatigue properties, strength, and wettability. Lead-free solder is gaining much attention as the environmental effects of lead in industrial products is recognized, and as a result of Europe's RoHS legislation to remove lead and other hazardous materials from electronics. Japanese electronics companies have also looked at Pb-free solder for its industrial advantages.
Typical alloys are 3–4% silver, 0.5–0.7% copper, and the balance (95%+) tin. For example, the common "SAC305" solder is 3.0% silver and 0.5% copper. Cheaper alternatives with less silver are used in some applications, such as SAC105 and SAC0307 (0.3% silver, 0.7% copper), at the expense of a somewhat higher melting point. | 0 | Metallurgy |
A slippery sequence is a small section of codon nucleotide sequences (usually UUUAAAC) that controls the rate and chance of ribosomal frameshifting. A slippery sequence causes a faster ribosomal transfer which in turn can cause the reading ribosome to "slip." This allows a tRNA to shift by 1 base (−1) after it has paired with its anticodon, changing the reading frame. A −1 frameshift triggered by such a sequence is a programmed −1 ribosomal frameshift. It is followed by a spacer region, and an RNA secondary structure. Such sequences are common in virus polyproteins.
The frameshift occurs due to wobble pairing. The Gibbs free energy of secondary structures downstream give a hint at how often frameshift happens. Tension on the mRNA molecule also plays a role. A list of slippery sequences found in animal viruses is available from Huang et al.
Slippery sequences that cause a 2-base slip (−2 frameshift) have been constructed out of the HIV UUUUUUA sequence. | 1 | Gene expression + Signal Transduction |
SPIKE (Signaling Pathways Integrated Knowledge Engine) is a database of highly curated interactions for particular human pathways. | 1 | Gene expression + Signal Transduction |
Nuclear pre-mRNA introns (spliceosomal introns) are characterized by specific intron sequences located at the boundaries between introns and exons. These sequences are recognized by spliceosomal RNA molecules when the splicing reactions are initiated. In addition, they contain a branch point, a particular nucleotide sequence near the 3 end of the intron that becomes covalently linked to the 5 end of the intron during the splicing process, generating a branched intron. Apart from these three short conserved elements, nuclear pre-mRNA intron sequences are highly variable. Nuclear pre-mRNA introns are often much longer than their surrounding exons. | 1 | Gene expression + Signal Transduction |
The orientation of crystallites can be random with no preferred direction, called random texture, or directed, possibly due to growth and processing conditions. While the structure of a single crystal is highly ordered and its lattice is continuous and unbroken, amorphous materials, such as glass and many polymers, are non-crystalline and do not display any structures, as their constituents are not arranged in an ordered manner. Polycrystalline structures and paracrystalline phases are in between these two extremes. Polycrystalline materials, or polycrystals, are solids that are composed of many crystallites of varying size and orientation. Most materials are polycrystalline, made of a large number crystallites held together by thin layers of amorphous solid. Most inorganic solids are polycrystalline, including all common metals, many ceramics, rocks, and ice.
The areas where crystallites meet are known as grain boundaries. | 0 | Metallurgy |
RoXaN (Rotavirus X-associated non-structural protein) also known as ZC3H7B (zinc finger CCCH-type containing 7B), is a protein that in humans is encoded by the ZC3H7B gene. RoXaN is a protein that contains tetratricopeptide repeat and leucine-aspartate repeat as well as zinc finger domains. This protein also interacts with the rotavirus non-structural protein NSP3. | 1 | Gene expression + Signal Transduction |
DESs are fluids generally composed of two or three cheap and safe components that are capable of self-association, often through hydrogen bond interactions, to form eutectic mixtures with a melting point lower than that of each individual component. DESs are generally liquid at temperatures lower than 100 °C, and they exhibit similar physico-chemical properties to traditional ILs, while being much cheaper and environmentally friendlier. Most of them are mixtures of choline chloride and a hydrogen-bond donor (e.g., urea, ethylene glycol, malonic acid) or mixtures of choline chloride with a hydrated metal salt. Other choline salts (e.g. acetate, citrate, nitrate) have a much higher costs or need to be synthesised, and the DES formulated from these anions are typically much more viscous and can have higher conductivities than for choline chloride. This results in lower plating rates and poorer throwing power and for this reason chloride-based DES systems are still favoured. For instance, Reline (a 1:2 mixture of choline chloride and urea) has been used to selectively recover Zn and Pb from a mixed metal oxide matrix. Similarly, Ethaline (a 1: 2 mixture of choline chloride and ethylene glycol) facilitates metal dissolution in electropolishing of steels. DESs have also demonstrated promising results to recover metals from complex mixtures such Cu/Zn and Ga/As, and precious metals from minerals. It has also been demonstrated that metals can be recovered from complex mixtures by electrocatalysis using a combination of DESs as lixiviants and an oxidising agent, while metal ions can be simultaneously separated from the solution by electrowinning. | 0 | Metallurgy |
The gal operon of E. coli consists of 4 structural genes: galE (epimerase), galT (galactose transferase), galK (galactokinase), and galM (mutarotase) which are transcribed from two overlapping promoters, PG1 (+1) and PG2 (-5), upstream from galE. GalE encodes for an epimerase that converts UDP-glucose into UDP-galactose. This is required for the formation of UDP-galactose for cell wall biosynthesis, in particular the cell wall component lipopolysaccharide, even when cells are not using galactose as a carbon/energy source. GalT encodes for the protein galactosyltransferase which catalyzes the transfer of a galactose sugar to an acceptor, forming a glycosidic bond. GalK encodes for a kinase that phosphorylates α-D-galactose to galactose 1-phosphate. Lastly, galM catalyzes the conversion of β-D-galactose to α-D-galactose as the first step in galactose metabolism.
The gal operon contains two operators, O (for external) and O (for internal). The former is just upstream of the promoter, and the latter is just after the galE gene (the first gene in the operon). These operators bind the repressor, GalR, which is encoded from outside the operator region. For this repressor protein to function properly, the operon also contains a histone binding site to facilitate this process.
An additional site, known as the activating site, is found following the external operator, but upstream of PG2. This site serves as the binding region for the cAMP-CRP complex, which modulates the activity of the promoters and thus, gene expression. | 1 | Gene expression + Signal Transduction |
References to silicon carbide heating elements exist from the early 20th century when they were produced by Acheson's Carborundum Co. in the U.S. and EKL in Berlin. Silicon carbide offered increased operating temperatures compared with metallic heaters. Silicon carbide elements are used today in the melting of glass and non-ferrous metal, heat treatment of metals, float glass production, production of ceramics and electronics components, igniters in pilot lights for gas heaters, etc. | 0 | Metallurgy |
Transcription factor 7-like 2 (T-cell specific, HMG-box), also known as TCF7L2 or TCF4, is a protein acting as a transcription factor that, in humans, is encoded by the TCF7L2 gene. The TCF7L2 gene is located on chromosome 10q25.2–q25.3, contains 19 exons. As a member of the TCF family, TCF7L2 can form a bipartite transcription factor and influence several biological pathways, including the Wnt signalling pathway.
Single-nucleotide polymorphisms (SNPs) in this gene are especially known to be linked to higher risk to develop type 2 diabetes, gestational diabetes, multiple neurodevelopmental disorders including schizophrenia and autism spectrum disorder, as well as other diseases. The SNP rs7903146, within the TCF7L2 gene, is, to date, the most significant genetic marker associated with type 2 diabetes risk. | 1 | Gene expression + Signal Transduction |
Originally, the use of laser-induced shock waves on metals to achieve property or functional benefits was referred to as laser shock processing, a broader, more inclusive term. As it happened, laser peening was the first commercial aspect of laser shock processing. However, laser-induced shock waves have found uses in other industrial applications outside of surface enhancement technologies.
One application is for metal shaping or forming. By selectively laser shocking areas on the surface of metal sheets or plates, or smaller items such as airfoils, the associated compressive residual stresses cause the material to flex in a controllable manner. In this way a particular shape can be imparted to a component, or a distorted component might be brought back into the desired shape. Thus, this process is capable of bringing manufactured parts back into design tolerance limits and form shaping thin section parts.
Another variation is to use the shock wave for spallation testing of materials. This application is based on the behavior of shockwaves to reflect from the rear free surface of a work piece as a tensile wave. Depending on the material properties and the shock wave characteristics, the reflected tensile wave may be strong enough to form microcracks or voids near the back surface, or actually "blow-off" or spall material from the back surface. This approach has some value for testing ballistic materials.
Use of laser shocks to measure the bond strength of coatings on metals has been developed over a period of years in France called LASAT for Laser Adhesion Test. This application is also based on the behavior of shockwaves to reflect from the rear free surface of a work piece as a tensile wave. If the back surface is coated with an adherent coating, the tensile wave can be tailored to fracture the bond upon reflection from the surface. By controlling the characteristics of the shock wave, the bond strength of the coating can be measured, or alternatively, determined in a comparative sense.
Careful tailoring of the shockwave shape and intensity has also enabled the inspection of bonded composite structures via laser shocking. The technology, termed Laser Bond Inspection initiates a shockwave that reflects off the backside of a bonded structure and returns as a tensile wave. As the tensile wave passes back through the adhesive bond, depending on the strength of the bond and the peak tensile stress of the stress wave, the tensile wave will either pass through the bond or rupture it. By controlling the pressure of the tensile wave this procedure is capable of reliably locally testing adhesion strength between bonded joints. This technology is most often found in application to bonded fiber composite material structures but has also been shown to be successful in evaluating bonds between metal-composite material. Fundamental issues are also studied to characterize and quantify the effect of shock wave produced by laser inside these complex materials. | 0 | Metallurgy |
The Jameson Cell has been adopted by Shell Canada and Syncrude for floating bitumen in the oil sands industry (see Bitumen flotation). Syncrude bought an additional eight 500 mm downcomers for its plant in 2012. | 0 | Metallurgy |
Although polyadenylation is seen in almost all organisms, it is not universal. However, the wide distribution of this modification and the fact that it is present in organisms from all three domains of life implies that the last universal common ancestor of all living organisms, it is presumed, had some form of polyadenylation system. A few organisms do not polyadenylate mRNA, which implies that they have lost their polyadenylation machineries during evolution. Although no examples of eukaryotes that lack polyadenylation are known, mRNAs from the bacterium Mycoplasma gallisepticum and the salt-tolerant archaean Haloferax volcanii lack this modification.
The most ancient polyadenylating enzyme is polynucleotide phosphorylase. This enzyme is part of both the bacterial degradosome and the archaeal exosome, two closely related complexes that recycle RNA into nucleotides. This enzyme degrades RNA by attacking the bond between the 3′-most nucleotides with a phosphate, breaking off a diphosphate nucleotide. This reaction is reversible, and so the enzyme can also extend RNA with more nucleotides. The heteropolymeric tail added by polynucleotide phosphorylase is very rich in adenine. The choice of adenine is most likely the result of higher ADP concentrations than other nucleotides as a result of using ATP as an energy currency, making it more likely to be incorporated in this tail in early lifeforms. It has been suggested that the involvement of adenine-rich tails in RNA degradation prompted the later evolution of polyadenylate polymerases (the enzymes that produce poly(A) tails with no other nucleotides in them).
Polyadenylate polymerases are not as ancient. They have separately evolved in both bacteria and eukaryotes from CCA-adding enzyme, which is the enzyme that completes the 3′ ends of tRNAs. Its catalytic domain is homologous to that of other polymerases. It is presumed that the horizontal transfer of bacterial CCA-adding enzyme to eukaryotes allowed the archaeal-like CCA-adding enzyme to switch function to a poly(A) polymerase. Some lineages, like archaea and cyanobacteria, never evolved a polyadenylate polymerase.
Polyadenylate tails are observed in several RNA viruses, including Influenza A, Coronavirus, Alfalfa mosaic virus, and Duck Hepatitis A. Some viruses, such as HIV-1 and Poliovirus, inhibit the cells poly-A binding protein (PABPC1) in order to emphasize their own genes expression over the host cell's. | 1 | Gene expression + Signal Transduction |
Lower pH and lower applied redox potential facilitate the evolution and the enrichment of hydrogen during the process of SCC, thus increasing the SCC intensity.
* Certain austenitic stainless steels and aluminium alloys crack in the presence of chlorides. This limits the usefulness of austenitic stainless steel for containing water with higher than a few parts per million content of chlorides at temperatures above ;
* mild steel cracks in the presence of alkali (e.g. boiler cracking and caustic stress corrosion cracking) and nitrates;
* copper alloys crack in ammoniacal solutions (season cracking);
* high-tensile steels have been known to crack in an unexpectedly brittle manner in a whole variety of aqueous environments, especially when chlorides are present.
With the possible exception of the latter, which is a special example of hydrogen cracking, all the others display the phenomenon of subcritical crack growth, i.e. small surface flaws propagate (usually smoothly) under conditions where fracture mechanics predicts that failure should not occur. That is, in the presence of a corrodent, cracks develop and propagate well below critical stress intensity factor (). The subcritical value of the stress intensity, designated as , may be less than 1% of . | 0 | Metallurgy |
In prokaryotes, the term corepressor is used to denote the activating ligand of a repressor protein. For example, the E. coli tryptophan repressor (TrpR) is only able to bind to DNA and repress transcription of the trp operon when its corepressor tryptophan is bound to it. TrpR in the absence of tryptophan is known as an aporepressor and is inactive in repressing gene transcription. Trp operon encodes enzymes responsible for the synthesis of tryptophan. Hence TrpR provides a negative feedback mechanism that regulates the biosynthesis of tryptophan.
In short tryptophan acts as a corepressor for its own biosynthesis. | 1 | Gene expression + Signal Transduction |
Many hypotheses about how scaffolds coordinate positive and negative feedback come from engineered scaffolds and mathematical modeling. In three-kinase signaling cascades, scaffolds bind all three kinases, enhancing kinase specificity and restricting signal amplification by limiting kinase phosphorylation to only one downstream target. These abilities may be related to stability of the interaction between the scaffold and the kinases, the basal phosphatase activity in the cell, scaffold location, and expression levels of the signaling components. | 1 | Gene expression + Signal Transduction |
Aluminum, copper, molybdenum, cobalt, mercury reserves and most importantly electricity for the smelting process has led to the development of non-ferrous metallurgy. The Zeylik mine in Daskasan district is the main provider of the alunite for aluminum production. The extracted ore here transported through Guschu-Alabashli railway to the aluminum plant located in Ganja city. The obtained aluminum oxide is brought to Sumgayit aluminum plant in order produce aluminum. Ganja Aluminum Plant produces sulfuric acid, aluminum oxide, and potassium fertilizer through extracted ore from Zalik deposit in Dashkesen. Aluminum oxide is also produced in Sumgait. AzerGold CJSC (created by the Presidential Decree No. 1047 on February 11, 2015) implements exploration, management, and also extraction, processing and sale of precious and non-ferrous metal ore deposits located within the borders of the country. In 2017, the volume of exports of precious metals carried out by this company amounted to 77340 million dollars. | 0 | Metallurgy |
Galvanic shock or oral galvanism is a term used for the association of oral symptoms due to electric currents occurring between different types of metal used in amalgam dental fillings and their interactions with the electrolytes in saliva. Other than individual sensitivity to amalgam, which can produce oral lesions, no associated adverse effects to amalgam have been found. However, Mutter in a German study concluded that "removal of dental amalgam leads to permanent improvement of various chronic complaints in a relevant number of patients in various trials".
The condition of galvanic shock was originally proposed in 1878, and became well known in Sweden during the 1970s and 80s, because of a campaign to raise awareness, and replace dental amalgam fillings containing mercury with other compounds such as ceramic or polymer restorations. | 0 | Metallurgy |
Interfacial energy affects the mechanisms of grain boundary sliding and dislocation transmission. Higher interfacial energy promotes greater resistance to grain boundary sliding, as the higher energy barriers inhibit the relative movement of adjacent grains. Additionally, dislocations that encounter grain boundaries can either transmit across the boundary or be reflected back into the same grain. The interfacial energy influences the likelihood of dislocation transmission, with higher interfacial energy barriers impeding dislocation motion and enhancing grain boundary strengthening. | 0 | Metallurgy |
During DNA damage or cellular stress PARPs are activated, leading to an increase in the amount of poly(ADP-ribose) and a decrease in the amount of NAD. For over a decade it was thought that PARP1 was the only poly(ADP-ribose)polymerase in mammalian cells, therefore this enzyme has been the most studied. Caspases are a family of cysteine proteases that are known to play an essential role in programmed cell death. This protease cleaves PARP-1 into two fragments, leaving it completely inactive, to limit poly(ADP-ribose) production. One of its fragments migrates from the nucleus to the cytoplasm and is thought to become a target of autoimmunity.
During caspase-independent apoptosis, also called parthanatos, poly(ADP-ribose) accumulation can occur due to activation of PARPs or inactivation of poly(ADP-ribose)glycohydrolase, an enzyme that hydrolyses poly(ADP-ribose) to produce free ADP-ribose. Studies have shown poly(ADP-ribose) drives the translocation of the apoptosis inducing factor protein to the nucleus where it will mediate DNA fragmentation. It has been suggested that if a failure of caspase activation under stress conditions were to occur, necroptosis would take place. Overactivation of PARPs has led to a necrotic cell death regulated by the tumor necrosis factor protein. Though the mechanism is not yet understood, PARP inhibitors have been shown to affect necroptosis. | 1 | Gene expression + Signal Transduction |
Transcription can also be studied at the level of individual cells by single-cell transcriptomics. Single-cell RNA sequencing (scRNA-seq) is a recently developed technique that allows the analysis of the transcriptome of single cells, including bacteria. With single-cell transcriptomics, subpopulations of cell types that constitute the tissue of interest are also taken into consideration. This approach allows to identify whether changes in experimental samples are due to phenotypic cellular changes as opposed to proliferation, with which a specific cell type might be overexpressed in the sample. Additionally, when assessing cellular progression through differentiation, average expression profiles are only able to order cells by time rather than their stage of development and are consequently unable to show trends in gene expression levels specific to certain stages. Single-cell trarnscriptomic techniques have been used to characterize rare cell populations such as circulating tumor cells, cancer stem cells in solid tumors, and embryonic stem cells (ESCs) in mammalian blastocysts.
Although there are no standardized techniques for single-cell transcriptomics, several steps need to be undertaken. The first step includes cell isolation, which can be performed using low- and high-throughput techniques. This is followed by a qPCR step and then single-cell RNAseq where the RNA of interest is converted into cDNA. Newer developments in single-cell transcriptomics allow for tissue and sub-cellular localization preservation through cryo-sectioning thin slices of tissues and sequencing the transcriptome in each slice. Another technique allows the visualization of single transcripts under a microscope while preserving the spatial information of each individual cell where they are expressed. | 1 | Gene expression + Signal Transduction |
Synaptic transmission can be changed by previous activity. These changes are called synaptic plasticity and may result in either a decrease in the efficacy of the synapse, called depression, or an increase in efficacy, called potentiation. These changes can either be long-term or short-term. Forms of short-term plasticity include synaptic fatigue or depression and synaptic augmentation. Forms of long-term plasticity include long-term depression and long-term potentiation. Synaptic plasticity can be either homosynaptic (occurring at a single synapse) or heterosynaptic (occurring at multiple synapses). | 1 | Gene expression + Signal Transduction |
Another useful imaging mode is differential interference contrast (DIC), which is usually obtained with a system designed by the Polish physicist Georges Nomarski. This system gives the best detail. DIC converts minor height differences on the plane-of-polish, invisible in BF, into visible detail. The detail in some cases can be quite striking and very useful. If an ST filter is used along with a Wollaston prism, color is introduced. The colors are controlled by the adjustment of the Wollaston prism, and have no specific physical meaning, per se. But, visibility may be better. | 0 | Metallurgy |
The pits that penetrate the bore are usually covered in a hard pale green nodule of copper sulfate and copper hydroxide salts. If the nodule is removed a hemispherical pit is revealed filled with coarse crystals of red cuprous oxide and green cuprous chloride. The pits are often referred to as Type 1 pits and the form of attack as Type 1 pitting. | 0 | Metallurgy |
In 1945 there were 38 furnaces worldwide, each with a capacity of 1 Mt/year. The process was favored in Germany due to the autarky policy of the Nazi regime, which prioritized the use of low-quality domestic iron ore. The transfer of technology between Nazi Germany and Imperial Japan led to the Japanese Empire benefiting from this process. Furnaces were installed in the co-prosperity sphere and operated by Japanese technicians. By the eve of the Pacific War, the process was being used in four steelworks in Japan.
After World War II all installations in Germany, China, and North Korea were dismantled, with 29 furnaces sent to the USSR as war reparations. Only the Japanese and Czechoslovakian plants remained functional.
In the 1950s Krupp rebuilt several large furnaces in Spain, Greece, and Germany. The Czechoslovakians were the primary drivers, constructing 16 furnaces and increasing process efficiency. The Great Soviet Encyclopedia reports that over 65 industrial plants, ranging from 60 to 110 meters in length and 3.6 to 4.6 meters in diameter, were constructed between 1930 and 1950. By 1960, 50 furnaces were producing 2 million tons per year in several countries. | 0 | Metallurgy |
Sulfates in solution in contact with concrete can cause chemical changes to the cement, which can cause significant microstructural effects leading to the weakening of the cement binder (chemical sulfate attack). Sulfate solutions can also cause damage to porous cementitious materials through crystallization and recrystallization (salt attack). Sulfates and sulfites are ubiquitous in the natural environment and are present from many sources, including gypsum (calcium sulfate) often present as an additive in blended cements which include fly ash and other sources of sulfate. With the notable exception of barium sulfate, most sulfates are slightly to highly soluble in water. These include acid rain where sulfur dioxide in the airshed is dissolved in rainfall to produce sulfurous acid. In lightning storms, the dioxide is oxidized to trioxide making the residual sulfuric acid in rainfall even more highly acidic. Concrete sewage infrastructure is most commonly attacked by sulfuric acid and sulfate anions arising from the oxidation of sulfide present in the sewage. Sulfides are formed when sulfate-reducing bacteria present in sewer mains reduce the ubiquitous sulfate ions present in water drains into hydrogen sulfide gas (). is volatile and released from water in the sewage atmosphere. It dissolves in a thin film of water condensed onto the wall of the sewer ducts where it is also accompanied by hydrogeno-sulfide () and sulfide () ions. When and anions are further exposed to atmospheric oxygen or to oxygenated stormwater, they are readily oxidized and produce sulfuric acid (in fact acidic hydrogen ions accompanied by sulfate and bisulfate ions) according to the respective oxidation reactions:
or,
The corrosion often present in the crown (top) of concrete sewers is directly attributable to this process – known as crown rot corrosion. | 0 | Metallurgy |
Members of the BMP family were originally found to induce bone formation, as their name suggests. However, BMPs are very multifunctional and can also regulate apoptosis, cell migration, cell division, and differentiation. They also specify the anterior/posterior axis, induce growth, and regulate homeostasis.
The BMPs bind to the bone morphogenetic protein receptor type II (BMPR2). Some of the proteins of the BMP family are BMP4 and BMP7. BMP4 promotes bone formation, causes cell death, or signals the formation of epidermis, depending on the tissue it is acting on. BMP7 is crucial for kidney development, sperm synthesis, and neural tube polarization. Both BMP4 and BMP7 regulate mature ligand stability and processing, including degrading ligands in lysosomes. BMPs act by diffusing from the cells that create them. | 1 | Gene expression + Signal Transduction |
Another important regulator of translation is the interaction between 3′ UTR and the 5′ UTR.
The closed-loop structure inhibits translation. This has been observed in Xenopus laevis, in which eIF4E bound to the 5′ cap interacts with Maskin bound to CPEB on the 3′ UTR, creating translationally inactive transcripts. This translational inhibition is lifted once CPEB is phosphorylated, displacing the Maskin binding site, allowing for the polymerization of the PolyA tail, which can recruit the translational machinery by means of PABP. However, it is important to note that this mechanism has been under great scrutiny. | 1 | Gene expression + Signal Transduction |
A significant indentation on the middle section of the pillar, approximately from the current courtyard ground level, has been shown to be the result of a cannonball fired at close range. The impact caused horizontal fissuring of the column in the area diametrically opposite to the indentation site, but the column itself remained intact. While no contemporaneous records, inscriptions, or documents describing the event are known to exist, historians generally agree that Nadir Shah is likely to have ordered the pillar's destruction during his invasion of Delhi in 1739, as he would have considered a Hindu temple monument undesirable within an Islamic mosque complex. Alternatively, he may have sought to dislodge the decorative top portion of the pillar in search of hidden precious stones or other items of value.
No additional damage attributable to cannon fire has been found on the pillar, suggesting that no further shots were taken. Historians have speculated that ricocheting fragments of the cannonball may have damaged the nearby Quwwat-ul-Islam mosque, which suffered damage to its southwestern portion during the same period, and the assault on the pillar might have been abandoned as a result. | 0 | Metallurgy |
Rho-related GTPases from plants, otherwise known as ROPs, are involved in cell polarity through the regulation of cytoskeleton components like actin and microtubules. Unlike mammalian cells, plant cells do not contain heterotrimeric G proteins like Cdc42, Rac, and Rho that are known to regulate cellular polarity.
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Stays made from puddled iron bar were used as a cheaper alternative to copper for joining the inner and outer firebox plates of steam locomotives. The incorporated stringers gave flexibility akin to stranded wire rope and stays made of the material were therefore resistant to snapping in service. Wrought iron rivets made from iron bar typically contained stringer filaments running the length of the rivet, but filaments at right angles to the tension, particularly beneath the head, caused weakness. | 0 | Metallurgy |
Smelting or the reduction of an ore to its metallic state is the primary source of experimentation in archaeometallurgy. In its simplest form smelting can be accomplished by placing an ore sample between two pieces of combusting charcoal in an oxygen reducing atmosphere with a compressed air source to feed the combustion and result in temperatures high enough to smelt metal. But to reach this final metallic state several things need to be done first including the processing of the ore to remove waste or gangue material, the possible roasting of the ore, the smelting of the ore, and then there is the possibility of refining the metal through a series of remelts. Then, through chemical or microscopic analysis, the products of the smelt are analyzed and compared with the findings of archaeological excavation in order to examine the likelihood of various manufacturing processes. | 0 | Metallurgy |
The nuclear protein in testis gene (i.e. NUTM1 gene) encodes (i.e. directs the synthesis of) a 1,132-amino acid protein termed NUT that is expressed almost exclusively in the testes, ovaries, and ciliary ganglion (i.e. a parasympathetic ganglion of nerve cells located just behind the eye). NUT protein facilitates the acetylation of chromatin (i.e. DNA-protein bundles) by histone acetyltransferase EP300 in testicular spermatids (cells that mature into sperms). This acetylation is a form of chromatin remodeling which compacts spermatid chromatin, a critical step required for the normal conduct of spermatogenesis, i.e. the maturation of spermatids into sperm. Male mice that lacked the mouse Nutm1 gene using a gene knockout method had abnormally small testes, lacked sperm in their cauda epididymis (i.e. tail of the epididymis which contains sperm in fertile male mice), and were completely sterile. These findings indicate that Nutm1 gene is essential for the development of normal fertility in male mice and suggest that the NUTM1 gene may play a similar role in men.
The NUTM1 gene is located in band 14 on the long (or "q") arm of chromosome 15. In the early 1990s, this gene was implicated in the development of certain epithelial cell cancers that: a) occurred in the midline structures of young people, b) were rapidly fatal, and c) consisted of poorly differentiated (i.e. not resembling any particular cell type), immature-appearing cells containing a BRD4-NUTM1 fusion gene. BRD4 is the bromodomain-containing protein 4 gene. A fusion gene is an abnormal gene consisting of parts from two different genes that form as a result of a large scale gene mutation such as a chromosomal translocation, interstitial deletion, or inversion. The BRD4-NUTM1 fusion gene is a translocation that encodes a fusion protein that has merged most of the protein coding region of the NUTM1 gene with a large part of the BRD4 gene located in band 13 on the short (i.e. "q") arm of chromosome 19. This translocation is notated as t(15;19)(q13, p13.1).
BRD4 protein recognizes acetylated lysine residues on proteins and by doing so participates in the regulation of DNA replication, DNA transcription, and thereby key cellular processes involved in the development of neoplasms (i.e. malignant or benign tissue growths). The product of the BRD4-NUTM1 fusion gene, BRD4-NUT protein, stimulates the expression of at least 4 relevant genes, MYC, TP63, SOX2, and MYB in cultured cells. All four of these genes are oncogenes, i.e., genes that when overexpressed and/or overly active promote the development of certain types of cancers. Overexpression of the MYC and SOX2 genes can also act to maintain cells in an undifferentiated stem cell-like state similar to the cells in the neoplasms driven by the BRD4-NUTM1 fusion gene. It is generally accepted that the BRD4-NUT protein promotes these neoplasms by maintaining their neoplastic cells in a perpetually undifferentiated, proliferative state. Further studies are needed to confirm and expand these views and to determine if any of the overexpressed gene products of the BRD4-NUT protein contribute to the development and/or progression, or can serve as targets for the treatment, of the neoplasms associated with the BRD4-NUTM1 fusion gene. These questions also apply to a wide range of neoplasms that have more recently been associated with the NUTM1 gene fused to other genes. | 1 | Gene expression + Signal Transduction |
For emulsions, flocculation describes clustering of individual dispersed droplets together, whereby the individual droplets do not lose their identity. Flocculation is thus the initial step leading to further ageing of the emulsion (droplet coalescence and the ultimate separation of the phases). Flocculation is used in mineral dressing, but can be also used in the design of physical properties of food and pharmaceutical products. | 0 | Metallurgy |
Piping corrosion circuit or Corrosion loop
/ Piping Circuitization and Corrosion Modelling, is carried out as part of either a Risk Based Inspection analysis (RBI) or Materials Operating Envelope analysis (MOE). It is the systematization of the piping components versus failure modes analysis into materials operating envelope. It groups piping materials / chemical make-up into systems / sub systems and assigns corrosion mechanisms. These are then monitored over the operating lifetime of the facility. This analysis is performed on circuit inspection results to determine and optimize circuit corrosion rates and measured thickness/dates for circuit components. Corrosion Circuits are utilized in the Integrity Management Plan (IMP) which forms a part of the overall Asset integrity management system and is an integral part of any RBI analysis. Many times a "system" will be a broad overview of the facilities process flow, broken by stream constituents, while a circuit level analysis breaks systems into smaller "circuits" that group common metallurgies, equal (or roughly equal) temperatures and pressures, and expected damage mechanisms. | 0 | Metallurgy |
There are six steps in the mechanism of TFIIB action in the formation of the PIC and transcription initiation:
#RNA polymerase II is recruited to DNA through the TFIIB B core and B ribbon.
#RNA polymerase II unwinds DNA, aided by the TFIIB B linker and B reader (open complex formation).
#RNA polymerase II selects a transcription start site, aided by the TFIIB B reader.
#RNA polymerase II forms the first phosphodiester bond.
#RNA polymerase II produces short abortive transcripts due to clashes between nascent RNA and the TFIIB B reader loop.
#Extension of nascent RNA to 12-13 nucleotides leads to ejection of TFIIB due to further clashes with TFIIB. | 1 | Gene expression + Signal Transduction |
* Gamma (γ): This phase composes the matrix of Ni-based superalloy. It is a solid solution fcc austenitic phase of the alloying elements. The alloying elements most found in commercial Ni-based alloys are, C, Cr, Mo, W, Nb, Fe, Ti, Al, V, and Ta. During the formation of these materials, as they cool from the melt, carbides precipitate, and at even lower temperatures γ' phase precipitates.
* Gamma prime (γ): This phase constitutes the precipitate used to strengthen the alloy. It is an intermetallic phase based on Ni(Ti,Al) which have an ordered FCC L1 structure. The γ phase is coherent with the matrix of the superalloy having a lattice parameter that varies by around 0.5%. Ni(Ti,Al) are ordered systems with Ni atoms at the cube faces and either Al or Ti atoms at the cube edges. As particles of γ precipitates aggregate, they decrease their energy states by aligning along the <100> directions forming cuboidal structures. This phase has a window of instability between 600 °C and 850 °C, inside of which γ will transform into the HCP η phase. For applications at temperatures below 650 °C, the γ" phase can be utilized for strengthening.
* Gamma double prime (γ"): This phase typically is NiNb or NiV and is used to strengthen Ni-based superalloys at lower temperatures (<650 °C) relative to γ'. The crystal structure of γ" is body-centered tetragonal (BCT), and the phase precipitates as 60 nm by 10 nm discs with the (001) planes in γ" parallel to the {001} family in γ. These anisotropic discs form as a result of lattice mismatch between the BCT precipitate and the FCC matrix. This lattice mismatch leads to high coherency strains which, together with order hardening, are the primary strengthening mechanisms. The γ" phase is unstable above approximately 650 °C.
* Carbide phases: Carbide formation is usually deleterious although in Ni-based superalloys they are used to stabilize the structure of the material against deformation at high temperatures. Carbides form at the grain boundaries, inhibiting grain boundary motion.
*Topologically close-packed (TCP) phases: The term "TCP phase" refers to any member of a family of phases (including the σ phase, the χ phase, the μ phase, and the Laves phase), which are not atomically close-packed but possess some close-packed planes with HCP stacking. TCP phases tend to be highly brittle and deplete the γ matrix of strengthening, solid solution refractory elements (including Cr, Co, W, and Mo). These phases form as a result of kinetics after long periods of time (thousands of hours) at high temperatures (>750 °C). | 0 | Metallurgy |
FSP can also be used to fabricate metal matrix composites at the nugget zone where we need the change of properties. Al 5052/SiC and some other composites were successfully fabricated. Even nano composites can also be fabricated by FSP. | 0 | Metallurgy |
Calcium carbide is used in carbide lamps. Water dripping on carbide produces acetylene gas, which burns and produces light. While these lamps gave steadier and brighter light than candles, they were dangerous in coal mines, where flammable methane gas made them a serious hazard. The presence of flammable gases in coal mines led to miner safety lamps such as the Davy lamp, in which a wire gauze reduces the risk of methane ignition. Carbide lamps were still used extensively in slate, copper, and tin mines where methane is not a serious hazard. Most miners' lamps have now been replaced by electric lamps.
Carbide lamps are still used for mining in some less wealthy countries, for example in the silver mines near Potosí, Bolivia. Carbide lamps are also still used by some cavers exploring caves and other underground areas, although they are increasingly being replaced in this use by LED lights.
Carbide lamps were also used extensively as headlamps in early automobiles, motorcycles and bicycles, but have been replaced entirely by electric lamps. | 0 | Metallurgy |
In general, prehistoric extraction of metals, particularly copper, involved two fundamental stages: first, the smelting of copper ore at temperatures exceeding 700 °C is needed to separate the gangue from the copper; second, melting the copper, which requires temperatures exceeding its melting point of 1080 °C. Given the available technology at the time, accomplishing these extreme temperatures posed a significant challenge. Early smelters developed ways to effectively increase smelting temperatures by feeding the fire with forced flows of oxygen.
Copper extraction in particular is of great interest in archeometallurgical studies since it dominated other metals in Mesopotamia from the early Chalcolithic until the mid-to-late sixth century BC. There is a lack of consensus among archaeometallurgists on the origin of non-ferrous extractive metallurgy. Some scholars believe that extractive metallurgy may have been simultaneously or independently discovered in several parts of the world. The earliest known use of pyrometallurgical extraction of copper occurred in Belovode, eastern Serbia, from the late sixth to early fifth millennium BC. However, there is also evidence of copper smelting in Tal-i-Iblis, southeastern Iran, which dates back to around the same period. During this period, copper smelters used large in-grown pits filled with coal, or crucibles to extract copper, but by the fourth millennium BC this practice had begun to phase out in favor of the smelting furnace, which had a larger production capacity. From the third millennium onward, the invention of the reusable smelting furnace was crucial to the success of large-scale copper production and the robust expansion of the copper trade through the Bronze Age.
The earliest silver objects began appearing in the late fourth millennium BC in Anatolia, Turkey. Prehistoric silver extraction is strongly associated with the extraction of the less valuable metal, lead; although evidence of lead extraction technology predates silver by at least 3 millennia. Silver and lead extractions are also associated because the argentiferous (silver-bearing) ores used in the process often contains both elements.
In general, prehistoric silver recovery was broken down into three phases: First, the silver-lead ore is roasted to separate the silver and lead from the gangue. The metals are then melted at high temperature ( greater than 1100 °C) in the crucible while air is blown over the molten metal (cupellation). Finally, lead is oxidized to form lead monoxide (PbO) or is absorbed into the walls of the crucible, leaving the refined silver behind.
The silver-lead cupellation method was first used in Mesopotamia between 4000 and 3500 BC. Silver artifacts, dating around 3600 BC, were discovered in Naqada, Egypt. Some of these cast silver artifacts contained less than 0.5% lead, which strongly indicates cupellation. | 0 | Metallurgy |
Calcineurin is linked to receptors for several brain chemicals including glutamate, dopamine and GABA. An experiment with genetically-altered mice that could not produce calcineurin showed similar symptoms as in humans with schizophrenia: impairment in working memory, attention deficits, aberrant social behavior, and several other abnormalities characteristic of schizophrenia. | 1 | Gene expression + Signal Transduction |
Bound to the 5-untranslated region of messenger RNA (mRNA), Morpholinos can interfere with progression of the ribosomal initiation complex from the 5 cap to the start codon. This prevents translation of the coding region of the targeted transcript (called "knocking down" gene expression). This is useful experimentally when an investigator wishes to know the function of a particular protein; Morpholinos provide a convenient means of knocking down expression of the protein and learning how that knockdown changes the cells or organism. Some Morpholinos knock down expression so effectively that, after degradation of preexisting proteins, the targeted proteins become undetectable by Western blot.
In 2016 a synthetic peptide-conjugated PMO (PPMO) was found to inhibit the expression of New Delhi Metallo-beta-lactamase, an enzyme that many drug-resistant bacteria use to destroy carbapenems. | 1 | Gene expression + Signal Transduction |
Fracturing is a brittle deformation process that creates permanent linear breaks, that are not accompanied by displacement within materials. These linear breaks or openings can be independent or interconnected. For fracturing to occur, the ultimate strength of the materials need to be exceeded to a point where the material ruptures. Rupturing is aided by the accumulations of high differential stress (the difference between the maximum and minimum stress acting on the object). Most fracture grow into faults. However, the term fault is only used when the fracture plane accommodate some degree of movement. Fracturing can happen across all scales, from microfractures to macroscopic fractures and joints in the rocks. | 0 | Metallurgy |
The single survivin gene can give rise to four different alternatively spliced transcripts:
# Survivin, which has a three-intron–four-exon structure in both the mouse and human.
# Survivin-2B, which has an insertion of an alternative exon 2.
# Survivin-Delta-Ex-3, which has exon 3 removed. The removal of exon 3 results in a frame shift that generates a unique carboxyl terminus with a new function. This new function may involve a nuclear localization signal. Moreover, a mitochondrial localization signal is also generated.
# Survivin-3B, which has an insertion of an alternative exon 3. | 1 | Gene expression + Signal Transduction |
Types B, R, and S thermocouples use platinum or a platinum/rhodium alloy for each conductor. These are among the most stable thermocouples, but have lower sensitivity than other types, approximately 10 μV/°C. Type B, R, and S thermocouples are usually used only for high-temperature measurements due to their high cost and low sensitivity. For type R and S thermocouples, HTX platinum wire can be used in place of the pure platinum leg to strengthen the thermocouple and prevent failures from grain growth that can occur in high temperature and harsh conditions. | 0 | Metallurgy |
Vacuum arc remelting (VAR) is a secondary remelting process for vacuum refining and manufacturing of ingots with improved chemical and mechanical homogeneity.
In critical military and commercial aerospace applications, material engineers commonly specify VIM-VAR steels. VIM means vacuum induction melted and VAR means vacuum arc remelted. VIM-VAR steels become bearings for jet engines, rotor shafts for military helicopters, flap actuators for fighter jets, gears in jet or helicopter transmissions, mounts or fasteners for jet engines, jet tail hooks and other demanding applications.
Most grades of steel are melted once and are then cast or teemed into a solid form prior to extensive forging or rolling to a metallurgically-sound form. In contrast, VIM-VAR steels go through two more highly purifying melts under vacuum. After melting in an electric arc furnace and alloying in an argon oxygen decarburization vessel, steels destined for vacuum remelting are cast into ingot molds. The solidified ingots then head for a vacuum induction melting furnace. This vacuum remelting process rids the steel of inclusions and unwanted gases while optimizing the chemical composition.
The VIM operation returns these solid ingots to the molten state in the contaminant-free void of a vacuum. This tightly controlled melt often requires up to 24 hours. Still enveloped by the vacuum, the hot metal flows from the VIM furnace crucible into giant electrode molds. A typical electrode is about 15 feet (5 m) tall and will be in various diameters. The electrodes solidify under vacuum.
For VIM-VAR steels, the surface of the cooled electrodes must be ground to remove surface irregularities and impurities before the next vacuum remelt. Then the ground electrode is placed in a VAR furnace. In a VAR furnace, the steel gradually melts drop-by-drop in the vacuum-sealed chamber. Vacuum arc remelting further removes lingering inclusions to provide superior steel cleanliness and remove gases like oxygen, nitrogen and hydrogen. Controlling the rate at which these droplets form and solidify ensures a consistency of chemistry and microstructure throughout the entire VIM-VAR ingot, making the steel more resistant to fracture or fatigue. This refinement process is essential to meet the performance characteristics of parts like a helicopter rotor shaft, a flap actuator on a military jet, or a bearing in a jet engine.
For some commercial or military applications, steel alloys may go through only one vacuum remelt, namely the VAR. For example, steels for solid rocket cases, landing gears, or torsion bars for fighting vehicles typically involve one vacuum remelt.
Vacuum arc remelting is also used in production of titanium and other metals which are reactive or in which high purity is required. | 0 | Metallurgy |
Fatigue failures of nitinol devices are a constant subject of discussion. Because it is the material of choice for applications requiring enormous flexibility and motion (e.g., peripheral stents, heart valves, smart thermomechanical actuators and electromechanical microactuators), it is necessarily exposed to much greater fatigue strains compared to other metals. While the strain-controlled fatigue performance of nitinol is superior to all other known metals, fatigue failures have been observed in the most demanding applications. There is a great deal of effort underway trying to better understand and define the durability limits of nitinol.
Nitinol is half nickel, and thus there has been a great deal of concern in the medical industry regarding the release of nickel, a known allergen and possible carcinogen. (Nickel is also present in substantial amounts in stainless steel and cobalt-chrome alloys.) When properly treated (via electropolishing or passivation), nitinol forms a very stable protective TiO layer that acts as a very effective and self-healing barrier against ion exchange. It has been repeatedly shown that nitinol releases nickel at a slower pace than stainless steel, for example. With that said, very early medical devices were made without electropolishing, and corrosion was observed. Today's nitinol vascular self-expandable metallic stents, for example, show no evidence of corrosion or nickel release, and the outcomes in patients with and without nickel allergies are indistinguishable.
There are constant and long-running discussions regarding inclusions in nitinol, both TiC and TiNiO. As in all other metals and alloys, inclusions can be found in nitinol. The size, distribution and type of inclusions can be controlled to some extent. Theoretically, smaller, rounder and few inclusions should lead to increased fatigue durability. In literature, some early works report to have failed to show measurable differences, while novel studies demonstrate a dependence of fatigue resistance on the typical inclusion size in an alloy.
Nitinol is difficult to weld, both to itself and other materials. Laser welding nitinol to itself is a relatively routine process. Strong joints between NiTi wires and stainless steel wires have been made using nickel filler. Laser and tungsten inert gas (TIG) welds have been made between NiTi tubes and stainless steel tubes. More research is ongoing into other processes and other metals to which nitinol can be welded.
Actuation frequency of nitinol is dependent on heat management, especially during the cooling phase. Numerous methods are used to increase the cooling performance, such as forced air, flowing liquids, thermoelectric modules (i.e. Peltier or semiconductor heat pumps), heat sinks, conductive materials and higher surface-to-volume ratio (improvements up to 3.3 Hz with very thin wires and up to 100 Hz with thin films of nitinol). The fastest nitinol actuation recorded was carried by a high voltage capacitor discharge which heated an SMA wire in a manner of microseconds, and resulted in a complete phase transformation (and high velocities) in a few milliseconds.
Recent advances have shown that processing of nitinol can expand thermomechanical capabilities, allowing for multiple shape memories to be embedded within a monolithic structure. Research on multi-memory technology is on-going and may deliver enhanced shape memory devices in the near future,
and the application of new materials and material structures, such hybrid shape memory materials (SMMs) and shape memory composites (SMCs). | 0 | Metallurgy |
C/EBPβ and δ are transiently induced during the early stages of adipocyte differentiation (adipogenesis), while C/EBPα is upregulated during the terminal stages of adipogenesis. In vitro and in vivo studies have demonstrated that each plays an important role in this process. For example, Murine Embryonic Fibroblasts (MEFs) from mice lacking both C/EBPβ and C/EBPδ show impaired adipocyte differentiation in response to adipogenic stimuli. In contrast, ectopic expression of C/EBPβ and δ in 3T3-L1 preadipocytes promotes adipogenesis, even in the absence of adipogenic stimuli. C/EBPβ and δ promote adipogenesis, at least in part by inducing the expression of the "master" adipogenic transcription factors C/EBPα and PPARγ.
C/EBPα is required both for adipogenesis and for normal adipocyte function. For example, mice lacking C/EBPα in all tissues except the liver (where it is needed to avoid postnatal lethality) show abnormal adipose tissue formation. Moreover, ectopic expression of C/EBPα in various fibroblast cell lines promotes adipogenesis. C/EBPα probably promotes adipogenesis by inducing the expression of PPARγ. | 1 | Gene expression + Signal Transduction |
Though the ropB protein has 7 histidines (H12, H81, H93, H144, H265, H266, and H277) structurally present, the ropB histidine switch primarily operates with a single functionally involved histidine (H144) conveniently placed to associate with ropB sidechains (Y176 and E185) that near each other upon the addition of a hydrogen ion to H144 in acidic conditions. Only one histidine (H12) is located on the N-domain while the rest lie in the C-terminal domain. | 1 | Gene expression + Signal Transduction |
The histidine phosphotransfer function can be carried out by proteins with at least two different architectures, both composed of a four-helix bundle but differing in the way the bundle is assembled. Most structurally characterized HPt proteins, such as the Hpt domain from the Escherichia coli protein ArcB and the Saccharomyces cerevisiae protein Ypd1, form the bundle as monomers. In the less common type, such as the Bacillus subtilis sporulation factor Spo0B or the Caulobacter crescentus protein ChpT, the bundle is assembled as a protein dimer, with similarity to the structure of histidine kinases. Monomeric HPt domains possess only one phosphorylatable histidine residue and interact with one response regulator, whereas dimers have two phosphorylation sites and can interact with two response regulators at the same time. Monomeric HPt domains have no enzymatic activity of their own and act purely as phosphate shuttles, while the dimeric Spo0B is catalytic; its phosphotransfer rate to the recipient response regulator is dramatically accelerated compared to histidine phosphate. Despite possessing a second domain with some similarity to ATPase domains, dimeric HPt proteins have not been shown to bind or hydrolyze ATP and lack key residues present in other ATPases.
The monomeric and dimeric forms do not have detectable sequence similarity and are most likely not evolutionarily related; they are instead examples of convergent evolution. Although dimeric HPts likely originate from degenerate histidine kinases, it is possible that monomeric HPts have a number of distinct origins, as there are few evolutionary constraints on the structure. | 1 | Gene expression + Signal Transduction |
SMA actuators are typically actuated electrically, where an electric current results in Joule heating. Deactivation typically occurs by free convective heat transfer to the ambient environment. Consequently, SMA actuation is typically asymmetric, with a relatively fast actuation time and a slow deactuation time. A number of methods have been proposed to reduce SMA deactivation time, including forced convection, and lagging the SMA with a conductive material in order to manipulate the heat transfer rate.
Novel methods to enhance the feasibility of SMA actuators include the use of a conductive "lagging". this method uses a thermal paste to rapidly transfer heat from the SMA by conduction. This heat is then more readily transferred to the environment by convection as the outer radii (and heat transfer area) are significantly greater than for the bare wire. This method results in a significant reduction in deactivation time and a symmetric activation profile. As a consequence of the increased heat transfer rate, the required current to achieve a given actuation force is increased. | 0 | Metallurgy |
Phosphatidic acid consists of a glycerol backbone, with, in general, a saturated fatty acid bonded to carbon-1, an unsaturated fatty acid bonded to carbon-2, and a phosphate group bonded to carbon-3. | 1 | Gene expression + Signal Transduction |
In these thermocouples (chromel–gold/iron alloy), the negative wire is gold with a small fraction (0.03–0.15 atom percent) of iron. The impure gold wire gives the thermocouple a high sensitivity at low temperatures (compared to other thermocouples at that temperature), whereas the chromel wire maintains the sensitivity near room temperature. It can be used for cryogenic applications (1.2–300 K and even up to 600 K). Both the sensitivity and the temperature range depend on the iron concentration. The sensitivity is typically around 15 μV/K at low temperatures, and the lowest usable temperature varies between 1.2 and 4.2 K. | 0 | Metallurgy |