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NCoR (nuclear receptor co-repressor) directly binds to the D and E domains of nuclear receptors and represses their transcriptional activity. Class I histone deacetylases are recruited by NCoR through SIN3, and NCoR directly binds to class II histone deacetylases. | 1 | Gene expression + Signal Transduction |
The mold cavity of a casting does not reflect the exact dimensions of the finished part due to a number of reasons. These modifications to the mold cavity are known as allowances and account for patternmaker's shrinkage, draft, machining, and distortion. In non-expendable processes, these allowances are imparted directly into the permanent mold, but in expendable mold processes they are imparted into the patterns, which later form the mold cavity. Note that for non-expendable molds an allowance is required for the dimensional change of the mold due to heating to operating temperatures.
For surfaces of the casting that are perpendicular to the parting line of the mold a draft must be included. This is so that the casting can be released in non-expendable processes or the pattern can be released from the mold without destroying the mold in expendable processes. The required draft angle depends on the size and shape of the feature, the depth of the mold cavity, how the part or pattern is being removed from the mold, the pattern or part material, the mold material, and the process type. Usually the draft is not less than 1%.
The machining allowance varies drastically from one process to another. Sand castings generally have a rough surface finish, therefore need a greater machining allowance, whereas die casting has a very fine surface finish, which may not need any machining tolerance. Also, the draft may provide enough of a machining allowance to begin with.
The distortion allowance is only necessary for certain geometries. For instance, U-shaped castings will tend to distort with the legs splaying outward, because the base of the shape can contract while the legs are constrained by the mold. This can be overcome by designing the mold cavity to slope the leg inward to begin with. Also, long horizontal sections tend to sag in the middle if ribs are not incorporated, so a distortion allowance may be required.
Cores may be used in expendable mold processes to produce internal features. The core can be of metal but it is usually done in sand. | 0 | Metallurgy |
Myristoylation plays a vital role in membrane targeting and signal transduction in plant responses to environmental stress. In addition, in signal transduction via G protein, palmitoylation of the α subunit, prenylation of the γ subunit, and myristoylation is involved in tethering the G protein to the inner surface of the plasma membrane so that the G protein can interact with its receptor. | 1 | Gene expression + Signal Transduction |
Non-expendable mold casting differs from expendable processes in that the mold need not be reformed after each production cycle. This technique includes at least four different methods: permanent, die, centrifugal, and continuous casting. This form of casting also results in improved repeatability in parts produced and delivers near net shape results. | 0 | Metallurgy |
On October 4, 2010, the Ajka alumina plant in Hungary had an incident where the western dam of its red mud reservoir collapsed. The reservoir was filled with 700,000 m of a mixture of red mud and water with a pH of 12. The mixture was released into the valley of Torna river and flooded parts of the city of Devecser and the villages of Kolontár and Somlóvásárhely. The incident resulted in 10 deaths, more than a hundred injuries, and contamination in lakes and rivers. | 0 | Metallurgy |
The Intronerator is a database of alternatively spliced genes and a database of introns for Caenorhabditis elegans. | 1 | Gene expression + Signal Transduction |
Fas ligand (FASL or CD95L) is a type-II transmembrane protein expressed on various types of cells, including cytotoxic T lymphocytes, monocytes, neutrophils, breast epithelial cells, vascular endothelial cells and natural killer (NK) cells. It binds with its receptor, called FAS receptor (also called CD95) and plays a crucial role in the regulation of the immune system and in induction of apoptosis, a programmed cell death. | 1 | Gene expression + Signal Transduction |
Type B (70%Pt/30%Rh–94%Pt/6%Rh, by weight) thermocouples are suited for use at up to 1800 °C. Type-B thermocouples produce the same output at 0 °C and 42 °C, limiting their use below about 50 °C. The emf function has a minimum around 21 °C, meaning that cold-junction compensation is easily performed, since the compensation voltage is essentially a constant for a reference at typical room temperatures. | 0 | Metallurgy |
Studies of ephaptic coupling have also focused on its role in the synchronization and timing of action potentials in neurons. In the simpler case of adjacent fibers that experience simultaneous stimulation the impulse is slowed because both fibers are limited to exchange ions solely with the interstitial fluid (increasing the resistance of the nerve). Slightly offset impulses (conduction velocities differing by less than 10%) are able to exchange ions constructively and the action potentials propagate slightly out of phase at the same velocity.
More recent research, however, has focused on the more general case of electric fields that affect a variety of neurons. It has been observed that local field potentials in cortical neurons can serve to synchronize neuronal activity. Although the mechanism is unknown, it is hypothesized that neurons are ephaptically coupled to the frequencies of the local field potential. This coupling may effectively synchronize neurons into periods of enhanced excitability (or depression) and allow for specific patterns of action potential timing (often referred to as spike timing). This effect has been demonstrated and modeled in a variety of cases.
A hypothesis or explanation behind the mechanism is "one-way", "master-slave", or "unidirectional synchronization" effect as mathematical and fundamental property of non-linear dynamic systems (oscillators like neurons) to synchronize under certain criteria. Such phenomenon was proposed and predicted to be possible between two HR neurons, since 2010 in simulations and modeling work by Hrg. It was also shown that such unidirectional synchronization or copy/paste transfer of neural dynamics from master to slave neurons, could be exhibited in different ways. Hence the phenomenon is of not only fundamental interest but also applied one from treating epilepsy to novel learning systems. A study in July 2023 found that mathematical models of ephaptic coupling predicted in vivo data of neural activity. The authors likened the electric field to a conductor of an orchestra and neurons to the musicians. Then the field,like the conductor, listens to the music and guides the musicians accordingly. In an opinion paper, they also suggested that not only neurons but other parts of the cytoskeleton generate electromagnetic fields that influence individual neurons, and called this cytoelectric coupling. Synchronization of neurons is in principle unwanted behavior, as brain would have zero information or be simply a bulb if all neurons would synchronize. Hence it is a hypothesis that neurobiology and evolution of brain coped with ways of preventing such synchronous behavior on large scale, using it rather in other special cases.
As models of brain function using only neuronal and gap junction connections fail to explain its complexity, ephaptic coupling is being added more to the equation to try and explain the isopotentiality of cortical astrocytes to maintain the bioelectromagnetic crosstalk between neurons and astrocytes in the neocortex. | 1 | Gene expression + Signal Transduction |
Many protein-coding genes have more than one polyadenylation site, so a gene can code for several mRNAs that differ in their 3′ end. The 3’ region of a transcript contains many polyadenylation signals (PAS). When more proximal (closer towards 5’ end) PAS sites are utilized, this shortens the length of the 3’ untranslated region (3 UTR) of a transcript. Studies in both humans and flies have shown tissue specific APA. With neuronal tissues preferring distal PAS usage, leading to longer 3’ UTRs and testis tissues preferring proximal PAS leading to shorter 3’ UTRs. Studies have shown there is a correlation between a genes conservation level and its tendency to do alternative polyadenylation, with highly conserved genes exhibiting more APA. Similarly, highly expressed genes follow this same pattern. Ribo-sequencing data (sequencing of only mRNAs inside ribosomes) has shown that mRNA isoforms with shorter 3’ UTRs are more likely to be translated.
Since alternative polyadenylation changes the length of the 3' UTR, it can also change which binding sites are available for microRNAs in the 3′ UTR. MicroRNAs tend to repress translation and promote degradation of the mRNAs they bind to, although there are examples of microRNAs that stabilise transcripts. Alternative polyadenylation can also shorten the coding region, thus making the mRNA code for a different protein, but this is much less common than just shortening the 3′ untranslated region.
The choice of poly(A) site can be influenced by extracellular stimuli and depends on the expression of the proteins that take part in polyadenylation. For example, the expression of CstF-64, a subunit of cleavage stimulatory factor (CstF), increases in macrophages in response to lipopolysaccharides (a group of bacterial compounds that trigger an immune response). This results in the selection of weak poly(A) sites and thus shorter transcripts. This removes regulatory elements in the 3′ untranslated regions of mRNAs for defense-related products like lysozyme and TNF-α. These mRNAs then have longer half-lives and produce more of these proteins. RNA-binding proteins other than those in the polyadenylation machinery can also affect whether a polyadenylation site is used, as can DNA methylation near the polyadenylation signal. In addition, numerous other components involved in transcription, splicing or other mechanisms regulating RNA biology can affect APA. | 1 | Gene expression + Signal Transduction |
In the 1870s, the French industrialist Pierre Manhès began his first attempts with a small, ordinary Bessemer converter of 50 kg in his factory in Vedène, then in factories in Éguilles, near Avignon. He sought to refine a matte with 25 to 30% copper previously melted in a crucible. But like Hollway, he did not succeed in completely refining the matte. The oxidation of undesirable elements occurred as expected, but the operation was quickly disrupted by the appearance of metallic copper. The matte, which was an ionic compound, was immiscible with the slag, but also with the molten metal. The latter, which is denser (ρ ≈ 9), went to the bottom of the converter and clogged the tuyeres.
Pierre Manhès then patented the use of additives whose oxidation would release enough heat to avoid getting stuck. In the end, it was the Frenchman Paul David, then an engineer in his factory in 1880, who suggested the solution. He proposed horizontal tuyeres placed at a sufficient distance from the bottom of the converter so that the copper could gather below them and the air blow constantly in the matte. By 1881, their converter was both technically operational and cost-effective.
In the autumn of 1884, the process was adopted in the United States by the Parrot Silver and Copper Company in Butte, Montana. The two types became larger and larger, increasing from a capacity of one ton to eight tons in 1912, and even fifteen tons for cylindrical converters in 1920. | 0 | Metallurgy |
The blast furnace remains an important part of modern iron production. Modern furnaces are highly efficient, including Cowper stoves to pre-heat the blast air and employ recovery systems to extract the heat from the hot gases exiting the furnace. Competition in industry drives higher production rates. The largest blast furnace in the world is in South Korea, with a volume around . It can produce around of iron per year.
This is a great increase from the typical 18th-century furnaces, which averaged about per year. Variations of the blast furnace, such as the Swedish electric blast furnace, have been developed in countries which have no native coal resources.
According to Global Energy Monitor, the blast furnace is likely to become obsolete to meet climate change objectives of reducing carbon dioxide emission, but BHP disagrees. An alternative process involving direct reduced iron is likely to succeed it, but this also needs to use a blast furnace to melt the iron and remove the gangue (impurities) unless the ore is very high quality. | 0 | Metallurgy |
Stress corrosion cracking (SCC) is the growth of a crack in a corrosive environment. It requires three conditions to take place: 1)corrosive environment 2)stress 3)susceptible material. SCC can lead to unexpected sudden and hence catastrophic failure of normally ductile metals under tensile stress. This is usually exacerbated at elevated temperature. SCC is highly chemically specific in that certain alloys are likely to undergo SCC only when exposed to a small number of chemical environments. It is common for SCC to go undetected prior to failure. SCC usually quite progresses rapidly after initial crack initiation, and is seen more often in alloys as opposed to pure metals. The corrosion engineer thus must be aware of this phenomenon. | 0 | Metallurgy |
The museum is also home to a large number of old tractors. Two D8 Caterpillars, a D9, a few large 1930s Caterpillars, some Best crawlers and many other examples of tracked tractors can be seen at the museum. The typical tractors such as Farmall, John Deere, Oliver, and Allis-Chalmers can be seen out at the museum, but there are more than a few rarer examples too. There is a 1924 Buffalo-Springfield road roller, a gigantic 1918 30-60 Aultman-Taylor gas tractor, a 1911 Fairbanks-Morse 15-25 kerosene tractor, a 1915 International Harvester Mogul 8-16, several Rumely Oil-Pulls, and many more. | 0 | Metallurgy |
In Arabidopsis, the protein DWF1 plays an enzymatic role in the biosynthesis of brassinosteroids, steroid hormones in plants that are required for growth. An interaction occurs between CaM and DWF1, and DWF1 being unable to bind CaM is unable to produce a regular growth phenotype in plants. Hence, CaM is essential for the DWF1 function in plant growth.
CaM binding proteins are also known to regulate reproductive development in plants. For instance, the CaM-binding protein kinase in tobacco acts as a negative regulator of flowering. However, these CaM-binding protein kinase are also present in the shoot apical meristem of tobacco and a high concentration of these kinases in the meristem causes a delayed transition to flowering in the plant.
S-locus receptor kinase (SRK) is another protein kinase that interacts with CaM. SRK is involved in the self-incompatibility responses involved in pollen-pistil interactions in Brassica.
CaM targets in Arabidopsis are also involved in pollen development and fertilization. Ca transporters are essential for pollen tube growth. Hence, a constant Ca gradient is maintained at the apex of pollen tube for elongation during the process of fertilization. Similarly, CaM is also essential at the pollen tube apex, where its primarily role involves the guidance of the pollen tube growth. | 1 | Gene expression + Signal Transduction |
The anodized aluminium layer is created by passing a direct current through an electrolytic solution, with the aluminium object serving as the anode (the positive electrode in an electrolytic cell). The current releases hydrogen at the cathode (the negative electrode) and oxygen at the surface of the aluminium anode, creating a build-up of aluminium oxide. Alternating current and pulsed current is also possible but rarely used. The voltage required by various solutions may range from 1 to 300 V DC, although most fall in the range of 15 to 21 V. Higher voltages are typically required for thicker coatings formed in sulfuric and organic acid. The anodizing current varies with the area of aluminium being anodized and typically ranges from 30 to 300 A/m.
Aluminium anodizing (eloxal or Electrolytic Oxidation of Aluminium) is usually performed in an acidic solution, typically sulphuric acid or chromic acid, which slowly dissolves the aluminium oxide. The acid action is balanced with the oxidation rate to form a coating with nanopores, 10–150 nm in diameter. These pores are what allow the electrolyte solution and current to reach the aluminium substrate and continue growing the coating to greater thickness beyond what is produced by auto-passivation. These pores allow for the dye to be absorbed, however, this must be followed by sealing or the dye will not stay. Dye is typically followed up by a clean nickel acetate seal. Because the dye is only superficial, the underlying oxide may continue to provide corrosion protection even if minor wear and scratches break through the dyed layer.
Conditions such as electrolyte concentration, acidity, solution temperature, and current must be controlled to allow the formation of a consistent oxide layer. Harder, thicker films tend to be produced by more concentrated solutions at lower temperatures with higher voltages and currents. The film thickness can range from under 0.5 micrometres for bright decorative work up to 150 micrometres for architectural applications. | 0 | Metallurgy |
Most commonly the term is used for the piles of waste earth materials removed during an excavation process.
* In surface mining (commonly called strip mining) for coal or other underground deposits, earth materials removed to expose the targeted deposit are piled up alongside the excavation site (commonly a strip mining pit) in spoil banks.
* A dredge in placer mining is used to dig up volumes of gravel and other earth materials, which are sent through sluices to remove gold or other minerals, and the remaining earth materials ("tailings") are deposited behind the dredge in spoil banks.
* In hydraulic mining, high-pressure jets of water dislodge earth materials, which are put through sluices to sort out gold or other minerals, and the residual earth materials are left in spoil banks.
* The excavation of ditches and canals results in spoil banks being left along the side of the canal or ditch.
Spoil banks can also refer to refuse heaps formed from removal of excess surface materials. For example, alongside livestock lots, spoil banks are formed of manure and other slurry periodically removed from the surface of the livestock lot areas. | 0 | Metallurgy |
*ADRBK1 can downregulate response to epinephrine
*AGPAT1 acyl 3 phosphoglycerol acyl transferase
*ARF1
*ARF3
*ARF4
*ARF5
*ARL2 RAS Superfamily
*CSF1 Colony stimulating factor not highly expressed constitutively at 5-12
*CSK C-src tyrosine kinase
*DCT dopachrome tautomerase
*EFNA3
*FKBP1A
*GDI1 GDP Dissociation inhibitor (Rab family)
*GNAS1 ubiquitously expressed, but differentially imprinted
*GNAI2
*HAX1 associated with tyrosine kinases
*ILK Integrin linked kinase
*MAPKAPK2
*MAP2K2
*MAP3K11
*PITPNM Phosphatidylinositol transfer protein
*RAC1 Ro GTPase involved with many signaling pathways
*RAP1B GTPase involved with cell adhesion
*RAGA Ras-related GTP Binding
*STK19
*STK24 Serine/Threonine Kinase
*STK25
*YWHAB Tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, beta polypeptide
*YWHAH Tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, h polypeptide
*YWHAQ Tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, theta polypeptide
*YWHAZ Tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide | 1 | Gene expression + Signal Transduction |
In the late 1990s, evidence began accumulating to suggest that some GPCRs are able to signal without G proteins. The ERK2 mitogen-activated protein kinase, a key signal transduction mediator downstream of receptor activation in many pathways, has been shown to be activated in response to cAMP-mediated receptor activation in the slime mold D. discoideum despite the absence of the associated G protein α- and β-subunits.
In mammalian cells, the much-studied β-adrenoceptor has been demonstrated to activate the ERK2 pathway after arrestin-mediated uncoupling of G-protein-mediated signaling. Therefore, it seems likely that some mechanisms previously believed related purely to receptor desensitisation are actually examples of receptors switching their signaling pathway, rather than simply being switched off.
In kidney cells, the bradykinin receptor B2 has been shown to interact directly with a protein tyrosine phosphatase. The presence of a tyrosine-phosphorylated ITIM (immunoreceptor tyrosine-based inhibitory motif) sequence in the B2 receptor is necessary to mediate this interaction and subsequently the antiproliferative effect of bradykinin. | 1 | Gene expression + Signal Transduction |
The EDF1 gene encodes a protein that acts as a transcriptional coactivator by interconnecting the general transcription factor TATA element-binding protein (TBP) and gene-specific activators.
TFIID and human mediator coactivator (THRAP3) complexes (mediator complex, plus THRAP3 protein) assemble cooperatively on promoter DNA, from which they become part of the RNAPII holoenzyme. | 1 | Gene expression + Signal Transduction |
A mill test report (MTR) and often also called a certified mill test report, certified material test report, mill test certificate (MTC), inspection certificate, certificate of test, or a host of other names, is a quality assurance document used in the metals industry that certifies a material's chemical and physical properties and states a product made of metal (steel, aluminum, brass or other alloys) complies with an international standards organization (such as ANSI, ASME, etc.) specific standards.
Mill here refers to an industry which manufactures and processes raw materials. | 0 | Metallurgy |
Following the invention of X-ray crystallography techniques in the 1910s, the atomic structure of many compounds was investigated. Most metals have relatively simple structures. However, in 1923 Linus Pauling reported on the structure of the intermetallic NaCd, which had such a complicated structure he was unable to fully explain it. Thirty years later, he concluded that NaCd contains 384 sodium and 768 cadmium atoms in each unit cell.
Most physical properties of CMAs show distinct differences with respect to the behavior of normal metallic alloys and therefore these materials possess a high potential for technological application.
The European Commission funded the Network of Excellence CMA from 2005 to 2010, uniting 19 core groups in 12 countries. From this emerged the European Integrated Center for the Development of New Metallic Alloys and Compounds (previously C-MAC, now ECMetAC), which connects researchers at 21 universities. | 0 | Metallurgy |
Type K (chromel–alumel) is the most common general-purpose thermocouple with a sensitivity of approximately 41 μV/°C. It is inexpensive, and a wide variety of probes are available in its −200 °C to +1350 °C (−330 °F to +2460 °F) range. Type K was specified at a time when metallurgy was less advanced than it is today, and consequently characteristics may vary considerably between samples. One of the constituent metals, nickel, is magnetic; a characteristic of thermocouples made with magnetic material is that they undergo a deviation in output when the material reaches its Curie point, which occurs for type K thermocouples at around 185 °C.
They operate very well in oxidizing atmospheres. If, however, a mostly reducing atmosphere (such as hydrogen with a small amount of oxygen) comes into contact with the wires, the chromium in the chromel alloy oxidizes. This reduces the emf output, and the thermocouple reads low. This phenomenon is known as green rot, due to the color of the affected alloy. Although not always distinctively green, the chromel wire will develop a mottled silvery skin and become magnetic. An easy way to check for this problem is to see whether the two wires are magnetic (normally, chromel is non-magnetic).
Hydrogen in the atmosphere is the usual cause of green rot. At high temperatures, it can diffuse through solid metals or an intact metal thermowell. Even a sheath of magnesium oxide insulating the thermocouple will not keep the hydrogen out.
Green rot does not occur in atmospheres sufficiently rich in oxygen, or oxygen-free. A sealed thermowell can be filled with inert gas, or an oxygen scavenger (e.g. a sacrificial titanium wire) can be added. Alternatively, additional oxygen can be introduced into the thermowell. Another option is using a different thermocouple type for the low-oxygen atmospheres where green rot can occur; a type N thermocouple is a suitable alternative. | 0 | Metallurgy |
This category groups pages related to Internal ribosome entry sites (IRESs) of RNA. IRESs are a nucleotide sequence that directs translation initiation in the middle of a messenger RNA (mRNA) as opposed to the usual process where initiation occurs at the five-prime end. | 1 | Gene expression + Signal Transduction |
Downregulation refers to the decrease in the number of receptor molecules. This is usually the result of receptor endocytosis. In this process, the bound LCGR-hormone complex binds arrestin and concentrates in clathrin coated pits. Clathrin coated pits recruit dynamin and pinch off from the cell surface, becoming clathrin-coated vesicles. Clathrin-coated vesicles are processed into endosomes, some of which are recycled to the cell surface while others are targeted to lysosomes. Receptors targeted to lysosomes are degraded. Use of long-acting agonists will downregulate the receptor population by promoting their endocytosis. | 1 | Gene expression + Signal Transduction |
Stress corrosion cracking (SCC) is the growth of crack formation in a corrosive environment. It can lead to unexpected and sudden failure of normally ductile metal alloys subjected to a tensile stress, especially at elevated temperature. SCC is highly chemically specific in that certain alloys are likely to undergo SCC only when exposed to a small number of chemical environments. The chemical environment that causes SCC for a given alloy is often one which is only mildly corrosive to the metal. Hence, metal parts with severe SCC can appear bright and shiny, while being filled with microscopic cracks. This factor makes it common for SCC to go undetected prior to failure. SCC often progresses rapidly, and is more common among alloys than pure metals. The specific environment is of crucial importance, and only very small concentrations of certain highly active chemicals are needed to produce catastrophic cracking, often leading to devastating and unexpected failure.
The stresses can be the result of the crevice loads due to stress concentration, or can be caused by the type of assembly or residual stresses from fabrication (e.g. cold working); the residual stresses can be relieved by annealing or other surface treatments. Unexpected and premature failure of chemical process equipment, for example, due to stress corrosion cracking constitutes a serious hazard in terms of safety of personnel, operating facilities and the environment. By weakening the reliability of these types of equipment, such failures also adversely affect productivity and profitability. | 0 | Metallurgy |
Serotonylation is a receptor independent signaling mechanism by which serotonin activates intracellular processes by creating long lasting covalent bonds upon proteins. It occurs through the modification of proteins by the attachment of serotonin on their glutamine residues. This happens through the enzyme transglutaminase and the creation of glutamyl-amide bonds. This process occurs following serotonin transportation into the cell rather on plasma membranes as with the brief interactions that serotonin has when it activates 5-HT receptors. | 1 | Gene expression + Signal Transduction |
Neurotransmitter release can be measured by determining the amplitude of the postsynaptic potential after triggering an action potential in the presynaptic neuron. Measuring neurotransmitter release this way can be problematic because the effect of the postsynaptic neuron to the same amount of released neurotransmitter can change over time. Another way is to measure vesicle fusion with the presynaptic membrane directly using a patch pipette. A cell membrane can be thought of as a capacitor in that positive and negative ions are stored on both sides of the membrane. The larger the area of membrane the more ions that are necessary to hold the membrane at a certain potential. In electrophysiology this means that a current injection into the terminal will take less time to charge a membrane to a given potential before vesicle fusion than it will after vesicle fusion. The time course to charge the membrane to a potential and the resistance of the membrane is measured and with these values the capacitance of the membrane can be calculated by the equation Tau/Resistance=Capacitance. With this technique researchers can measure synaptic vesicle release directly by measuring increases in the membrane capacitance of the presynaptic terminal. | 1 | Gene expression + Signal Transduction |
The pillar does not bear an inscription mentioning its erector, date or purpose. It is located at Dhar, which was the capital of the Paramara dynasty. According to the local tradition, the pillar commemorates a military victory of the 11th century Paramara king Bhoja, whose knowledge of iron metallurgy can be seen in his book Yuktikalpataru. Henry Cousens of Archaeological Survey of India (ASI) theorized that it was constructed by the later Paramara king Arjunavarman in 1210 CE, from the molten arms of an enemy force.
The Lat Masjid, in whose compound the pillar is located, was constructed with spolia from Hindu and Jain temples. R. Balasubramaniam theorizes that a Shiva temple previously occupied the site, and the pillar was originally located at the front of this temple, with a trishula (trident) at the top.
The two largest fragments have a number of holes at irregular intervals, on all sides. The depth of the holes ranges from , and their diameter ranges from . Because they are distributed unevenly, they do not appear to be slots for lamps (as in a deepa-stambha). Cousens speculated that these were used by the forgers and welders to handle the pillar with their instruments during the manufacturing process. Roessler agreed with this hypothesis, and proposed that these slots were also used to hold the pillar upright using iron anchors.
The pillar appears to have been built using horizontal forge welding technique. Brahm Prakash theorized that smaller sections, measuring to in length, were joined together to form the pillar. | 0 | Metallurgy |
Donetsk Metallurgical Plant also called Donetsk Iron and Steel Works is an enterprise of Donetsk, Ukraine. It is a ferrous metallurgy enterprise that is located in the Leninskyi district of Donetsk. | 0 | Metallurgy |
Human as well murine STAT4 genes lie next to STAT1 gene locus suggesting that the genes arose by gene duplication. STAT proteins have six functional domains: 1. N-terminal interaction domain – crucial for dimerization of inactive STATs and nuclear translocation; 2.helical coiled coil domain – association with regulatory factors; 3. central DNA-binding domain – binding to the enhancer region of IFN-γ activated sequence (GAS) family genes; 4. linker domain – assisting during the DNA binding process; 5. Src homology 2 (SH2) domain – critical for specific binding to the cytokine receptor after tyrosine phosphorylation; 6. C-terminal transactivation domain – triggering the transcriptional process. The length of the protein is 748 amino acids, and the molecular weight is 85 941 Dalton. | 1 | Gene expression + Signal Transduction |
Various solutions have been proposed for the challenging problem of network motif (NM) discovery. These algorithms can be classified under various paradigms such as exact counting methods, sampling methods, pattern growth methods and so on. However, motif discovery problem comprises two main steps: first, calculating the number of occurrences of a sub-graph and then, evaluating the sub-graph significance. The recurrence is significant if it is detectably far more than expected. Roughly speaking, the expected number of appearances of a sub-graph can be determined by a Null-model, which is defined by an ensemble of random networks with some of the same properties as the original network.
Until 2004, the only exact counting method for NM detection was the brute-force one proposed by Milo et al.. This algorithm was successful for discovering small motifs, but using this method for finding even size 5 or 6 motifs was not computationally feasible. Hence, a new approach to this problem was needed.
Here, a review on computational aspects of major algorithms is given and their related benefits and drawbacks from an algorithmic perspective are discussed. | 1 | Gene expression + Signal Transduction |
Many adhesion GPCRs undergo proteolytic events posttranslationally at highly conserved Cys-rich motifs known as GPCR proteolysis sites (GPS), located next to the first transmembrane region. This site is called the HL-S(T) site. Once this protein is cleaved, the pieces are expressed at the cell surface as a heterodimer. This cleavage is thought to happen from within the protein itself, through the conserved GAIN domain. This process seems to be similar to those found in other auto-proteolytic proteins such as the Ntn hydrolases and hedgehog proteins. | 1 | Gene expression + Signal Transduction |
It has been speculated that in any particular population, relatively few genes would show observable paramutation since the high penetrance of paramutagenic alleles (like B’ at the r1 locus in maize) would drive either the paramutagenic or paramutable allele to fixation. Paramutation at other loci with paramutagenic alleles with lower penetrance may persist, however, which may need to be taken into account by plant breeders.
Since there are examples of paramutation, or paramutation-like phenomena, in animals such as fruit flies and mice, it has been suggested that paramutation may explain the occurrence of some human diseases that exhibit non-Mendelian inheritance patterns. | 1 | Gene expression + Signal Transduction |
In addition to RTK pathway, fibroblast growth factors can also activate the JAK-STAT signaling pathway. Instead of carrying covalently associated tyrosine kinase domains, Jak-STAT receptors form noncovalent complexes with tyrosine kinases of the Jak (Janus kinase) class. These receptors bind are for erythropoietin (important for erythropoiesis), thrombopoietin (important for platelet formation), and interferon (important for mediating immune cell function).
After dimerization of the cytokine receptors following ligand binding, the JAKs transphosphorylate each other. The resulting phosphotyrosines attract STAT proteins. The STAT proteins dimerize and enter the nucleus to act as transcription factors to alter gene expression. In particular, the STATs transcribe genes that aid in cell proliferation and survival – such as myc.
Phenotype and survival of mice after knockout of some JAK or STAT genes: | 1 | Gene expression + Signal Transduction |
Biohydrometallurgy is used to perform processes involving metals, for example, microbial mining, oil recovery, bioleaching, water-treatment and others. Biohydrometallurgy is mainly used to recover certain metals from sulfide ores. It is usually utilized when conventional mining procedures are too expensive or ineffective in recovering a metal such as copper, cobalt, gold, lead, nickel, uranium and zinc. | 0 | Metallurgy |
Partial agonists are any chemical that can bind to a receptor without eliciting the maximum downstream response as compared to the response from a full agonist. A given partial agonist's affinity for a given receptor is also irrelevant to the consequent effect. An example is buprenorphine, a partial opioid receptor agonist used to treat opioid addictions by directly substituting for them without the same strength of effect. | 1 | Gene expression + Signal Transduction |
(p)ppGpp is created via pppGpp synthase, also known as RelA, and is converted from pppGpp to ppGpp via pppGpp phosphohydrolase. RelA is associated with about every one in two hundred ribosomes and it becomes activated when an uncharged transfer RNA (tRNA) molecule enters the A site of the ribosome, due to the shortage of amino acid required by the tRNA. If a mutant bacterium is relA it is said to be relaxed and no regulation of RNA production due to amino acid absence is seen. | 1 | Gene expression + Signal Transduction |
G activates the cAMP-dependent pathway by stimulating the production of cyclic AMP (cAMP) from ATP. This is accomplished by direct stimulation of the membrane-associated enzyme adenylate cyclase. cAMP can then act as a second messenger that goes on to interact with and activate protein kinase A (PKA). PKA can phosphorylate a myriad downstream targets.
The cAMP-dependent pathway is used as a signal transduction pathway for many hormones including:
* ADH – Promotes water retention by the kidneys (created by the magnocellular neurosecretory cells of the posterior pituitary)
* GHRH – Stimulates the synthesis and release of GH (somatotropic cells of the anterior pituitary)
* GHIH – Inhibits the synthesis and release of GH (somatotropic cells of anterior pituitary)
* CRH – Stimulates the synthesis and release of ACTH (anterior pituitary)
* ACTH – Stimulates the synthesis and release of cortisol (zona fasciculata of the adrenal cortex in the adrenal glands)
* TSH – Stimulates the synthesis and release of a majority of T4 (thyroid gland)
* LH – Stimulates follicular maturation and ovulation in women; or testosterone production and spermatogenesis in men
* FSH – Stimulates follicular development in women; or spermatogenesis in men
* PTH – Increases blood calcium levels. This is accomplished via the parathyroid hormone 1 receptor (PTH1) in the kidneys and bones, or via the parathyroid hormone 2 receptor (PTH2) in the central nervous system and brain, as well as the bones and kidneys.
* Calcitonin – Decreases blood calcium levels (via the calcitonin receptor in the intestines, bones, kidneys, and brain)
* Glucagon – Stimulates glycogen breakdown in the liver
* hCG – Promotes cellular differentiation, and is potentially involved in apoptosis.
* Epinephrine – released by the adrenal medulla during the fasting state, when body is under metabolic duress. It stimulates glycogenolysis, in addition to the actions of glucagon. | 1 | Gene expression + Signal Transduction |
The excess volume is another important property in the characterization of grain boundaries. Excess volume was first proposed by Bishop in a private communication to Aaron and Bolling in 1972. It describes how much expansion is induced by the presence of a GB and is thought that the degree and susceptibility of segregation is directly proportional to this. Despite the name the excess volume is actually a change in length, this is because of the 2D nature of GBs the length of interest is the expansion normal to the GB plane. The excess volume () is defined in the following way,
at constant temperature , pressure and number of atoms . Although a rough linear relationship between GB energy and excess volume exists the orientations where this relationship is violated can behave significantly differently affecting mechanical and electrical properties.
Experimental techniques have been developed which directly probe the excess volume and have been used to explore the properties of nanocrystalline copper and nickel. Theoretical methods have also been developed and are in good agreement. A key observation is that there is an inverse relationship with the bulk modulus meaning that the larger the bulk modulus (the ability to compress a material) the smaller the excess volume will be, there is also direct relationship with the lattice constant, this provides methodology to find materials with a desirable excess volume for a specific application. | 0 | Metallurgy |
A mold for casting an oxhide ingot was discovered in the LBA north palace at Ras Ibn Hani in Syria. It is made of fine-grained "ramleh", a shelly limestone. Archaeologists found burnt copper droplets around the mold. In spite of the questionable durability of limestone, Paul Craddock et al. concluded that limestone can be used for casting “large simple shapes” such as oxhide ingots. Evolution of carbon dioxide from the limestone would damage the metal surface that touched the mold. Thus, metal objects requiring surface detail could not be produced successfully.
This is not to say that oxhide ingots were normally cast in limestone molds. Using an experimental clay mold, Bass et al. argue that the ingot's smooth side was in contact with the mold while its rough side was exposed to the atmosphere. The roughness results from the interaction of the atmosphere and the cooling metal. | 0 | Metallurgy |
The effects of a particular signal transduction pathway can be very different among distinct cell types. For example, the same signal transduction pathway may promote the survival of one cell type but the maturation of another. This depends both on the nature of a cell but also on its particular state which may change over the course of its lifetime. Identifying cell types where a signal transduction pathway is operational is a first step to uncovering potentially new properties of this pathway.
The STAT3-Ser/Hes3 signaling axis has been shown to operate on various cell types. So far, research has mostly focused on stem cells and cancerous tissue and, more recently, in the function of the endocrine pancreas:
:* Fetal and adult mouse and rat neural stem cells.
:* Adult monkey (rhesus macaque) neural stem cells.
:* Human cancer stem cells from glioblastoma multiforme.
:* In a human prostate cancer cell line, STAT3-Ser was shown to promote tumorigenesis independently of STAT3-Tyr.
:* Chromaffin progenitor cells of the bovine adrenal medulla.
:* Mouse insulinoma cells (MIN6 cell line) and mouse pancreatic islet cells.
:* Mouse embryonic fibroblasts (MEF) during reprogramming to the induced pluripotent stem cell state.
:* Human embryonic stem cells
:* Mouse neural stem cells derived from induced pluripotent stem cells. | 1 | Gene expression + Signal Transduction |
Structurally, the lac repressor protein is a homotetramer. More precisely, the tetramer contains two DNA-binding subunits composed of two monomers each (a dimer of dimers). Each monomer consists of four distinct regions:
*An N-terminal DNA-binding domain (in which two LacI proteins bind a single operator site)
*A regulatory domain (sometimes called the core domain, which binds allolactose, an allosteric effector molecule)
*A linker that connects the DNA-binding domain with the core domain (sometimes called the hinge helix, which is important for allosteric communication)
*A C-terminal tetramerization region (which joins four monomers in an alpha-helix bundle)
DNA binding occurs via an N-terminal helix-turn-helix structural motif and is targeted to one of several operator DNA sequences (known as O, O and O). The O operator sequence slightly overlaps with the promoter, which increases the affinity of RNA polymerase for the promoter sequence such that it cannot enter elongation and remains in abortive initiation. Additionally, because each tetramer contains two DNA-binding subunits, binding of multiple operator sequences by a single tetramer induces DNA looping. | 1 | Gene expression + Signal Transduction |
Amongst Rgg-like proteins, it has been observed that the pH sensitive histidine (particularly H144) and interacting amino acids (Y176, Y182, and E185) of ropB of Streptococcus pyogenes are conserved in S. porcinus, S. pseudoporcinus, S. salivarius , L. pentosus, Enterococcus sp., L. aviaries, E. faecalis, and L. reuteri. Thus, suggesting the usage of a pH sensitive histidine switch complex with gene regulating effector molecules in a slew of other bacteria [See Also: allosteric regulation]. | 1 | Gene expression + Signal Transduction |
David Dye is a Professor of Metallurgy at Imperial College London. Dye specialises in fatigue and micromechanics of aerospace and nuclear materials, mainly Ni/Co superalloys, titanium, TWIP steel, and Zirconium alloys. | 0 | Metallurgy |
Expendable mold casting is a generic classification that includes sand, plastic, shell, plaster, and investment (lost-wax technique) moldings. This method of mold casting involves the use of temporary, non-reusable molds. | 0 | Metallurgy |
CKLF1 is the first member of the CKLF-like MARVEL transmembrane domain-containing family of proteins to be defined and the most investigated of its four isoforms. Studies conducted in freshly isolated cells, cultured cells, animals, and tissue samples indicate that CKLF1 is a chemokine-like chemotactic factor that acts through the CCR4 receptors on human CD4+ Th2 lymphocytes, neutrophils, monocytes, macrophages, dendritic cells, and perhaps other CCR4-receptor bearing cells. Preliminary findings suggest that the actions of CKLF1 on these CCR4-bearing cells may contribute to the maturation of various tissues such as blood cells and skeletal muscle from their precursor cells and the regulation of allergic (e.g. asthma), autoimmune (e.g. rheumatoid arthritis and the antiphospholipid syndrome), and inflammatory (e.g. acute respiratory distress syndrome) disorders. Other studies have found that: 1) the benign fibrous skin tumor, keloids, had higher levels of CKLF1 and CKLF1 mRNA than nearby normal skin tissues; 2) CKLF1 levels were higher in ovarian carcinoma tissues than nearby normal ovary tissues and patients with higher levels of CKLF1 in their ovarian cancer tissues had a more aggressive cancer than patients with lover levels of the protein in their ovarian cancer tissues; and 3) the levels of CKLF1 protein were higher in cancerous than nearby normal liver tissues in patients with hepatocellular carcinoma (HCC) and patients with higher HCC tissue levels of CKLF1 had poorer overall survival times than patients with lower levels of this protein in their HCC tissues. These results suggest that high levels of CKLF1 promote the development and/or progression of these three neoplasms although further studies are required to further define these relationships and to determine if CKLF1 can be used as a marker for their severity and/or a therapeutic target for treating them. | 1 | Gene expression + Signal Transduction |
Following the work on homeotic mutants by Ed Lewis, the phenomenology of homeosis in animals was further elaborated by discovery of a conserved DNA binding sequence present in many homeotic proteins.
Thus, the 60 amino acid DNA binding protein domain was named the homeodomain, while the 180 bp nucleotide sequence encoding it was named the homeobox. The homeobox gene clusters studied by Ed Lewis were named the Hox genes, although many more homeobox genes are encoded by animal genomes than those in the Hox gene clusters.
The homeotic-function of certain proteins was first postulated to be that of a "selector" as proposed by Antonio Garcia-Bellido.
By definition selectors were imagined to be (transcription factor) proteins that stably determined one of two possible cell fates for a cell and its cellular descendants in a tissue.
While most animal homeotic functions are associated with homeobox-containing factors, not all homeotic proteins in animals are encoded by homeobox genes, and further not all homeobox genes are necessarily associated with homeotic functions or (mutant) phenotypes.
The concept of homeotic selectors was further elaborated or at least qualified by Michael Akam in a so-called "post-selector gene" model that incorporated additional findings and "walked back" the "orthodoxy" of selector-dependent stable binary switches.
The concept of tissue compartments is deeply intertwined with the selector model of homeosis because the selector-mediated maintenance of cell fate can be restricted into different organizational units of an animal's body plan.
In this context, newer insights into homeotic mechanisms were found by Albert Erives and colleagues by focusing on enhancer DNAs that are co-targeted by homeotic selectors and different combinations of developmental signals.
This work identifies a protein biochemical difference between the transcription factors that function as homeotic selectors versus the transcription factors that function as effectors of developmental signaling pathways, such as the Notch signaling pathway and the BMP signaling pathway.
This work proposes that homeotic selectors function to "license" enhancer DNAs in a restricted tissue compartment so that the enhancers are enabled to read-out developmental signals, which are then integrated via polyglutamine-mediated aggregation. | 1 | Gene expression + Signal Transduction |
In crystallography, materials science and metallurgy, Vegards law is an empirical finding (heuristic approach) resembling the rule of mixtures. In 1921, Lars Vegard discovered that the lattice parameter of a solid solution of two constituents is approximately a weighted mean of the two constituents lattice parameters at the same temperature:
e.g., in the case of a mixed oxide of uranium and plutonium as used in the fabrication of MOX nuclear fuel:
Vegards law assumes that both components A and B in their pure form (i.e.', before mixing) have the same crystal structure. Here, is the lattice parameter of the solid solution, and are the lattice parameters of the pure constituents, and is the molar fraction of B in the solid solution.
Vegard's law is seldom perfectly obeyed; often deviations from the linear behavior are observed. A detailed study of such deviations was conducted by King. However, it is often used in practice to obtain rough estimates when experimental data are not available for the lattice parameter for the system of interest.
For systems known to approximately obey Vegard's law, the approximation may also be used to estimate the composition of a solution from knowledge of its lattice parameters, which are easily obtained from diffraction data. For example, consider the semiconductor compound . A relation exists between the constituent elements and their associated lattice parameters, , such that:
When variations in lattice parameter are very small across the entire composition range, Vegards law becomes equivalent to Amagats law. | 0 | Metallurgy |
In materials science parlance, dislocations are defined as line defects in a material's crystal structure. The bonds surrounding the dislocation are already elastically strained by the defect compared to the bonds between the constituents of the regular crystal lattice. Therefore, these bonds break at relatively lower stresses, leading to plastic deformation.
The strained bonds around a dislocation are characterized by lattice strain fields. For example, there are compressively strained bonds directly next to an edge dislocation and tensilely strained bonds beyond the end of an edge dislocation. These form compressive strain fields and tensile strain fields, respectively. Strain fields are analogous to electric fields in certain ways. Specifically, the strain fields of dislocations obey similar laws of attraction and repulsion; in order to reduce overall strain, compressive strains are attracted to tensile strains, and vice versa.
The visible (macroscopic) results of plastic deformation are the result of microscopic dislocation motion. For example, the stretching of a steel rod in a tensile tester is accommodated through dislocation motion on the atomic scale. | 0 | Metallurgy |
The periactive zone surrounds the active zone and is the site of endocytosis of the presynaptic terminal. In the periactive zone, scaffolding proteins such as intersectin 1 recruit proteins that mediate endocytosis such as dynamin, clathrin and endophilin. In Drosophila the intersectin homolog, Dap160, is located in the periactive zone of the neuromuscular junction and mutant Dap160 deplete synaptic vesicles during high frequency stimulation. | 1 | Gene expression + Signal Transduction |
Initiation of transcription requires promoter regions, which are specific nucleotide consensus sequences that tell the σ-factor on RNA polymerase where to bind to the DNA. The promoters are usually located 15 to 19 bases apart and are most commonly found upstream of the genes they control. RNA polymerase is made up of 4 subunits, which include two alphas, a beta, and a beta prime (α, α, β, and β). A fifth subunit, sigma (called the σ-factor), is only present during initiation and detaches prior to elongation. Each subunit plays a role in the initiation of transcription, and the σ-factor must' be present for initiation to occur. When all σ-factor is present, RNA polymerase is in its active form and is referred to as the holoenzyme. When the σ-factor detaches, it is in core polymerase form. The σ-factor recognizes promoter sequences at -35 and -10 regions and transcription begins at the start site (+1). The sequence of the -10 region is TATAAT and the sequence of the -35 region is TTGACA.
* The σ-factor binds to the -35 promoter region. At this point, the holoenzyme is referred to as the closed complex because the DNA is still double stranded (connected by hydrogen bonds).
*Once the σ-factor binds, the remaining subunits of the polymerase attach to the site. The high concentration of adenine-thymine bonds at the -10 region facilitates the unwinding of the DNA. At this point, the holoenzyme is called the open complex. This open complex is also called the transcription bubble. Only one strand of DNA, called the template strand (also called the noncoding strand or nonsense/antisense strand), gets transcribed.
*Transcription begins and short "abortive" nucleotide sequences approximately 10 base pairs long are produced. These short sequences are nonfunctional pieces of RNA that are produced and then released. Generally, this nucleotide sequence consists of about twelve base pairs and aids in contributing to the stability of RNA polymerase so it is able to continue along the strand of DNA.
* The σ-factor is needed to initiate transcription but is not needed to continue transcribing the DNA. The σ-factor dissociates from the core enzyme and elongation proceeds. This signals the end of the initiation phase and the holoenzyme is now in core polymerase form.
The promoter region is a prime regulator of transcription. Promoter regions regulate transcription of all genes within bacteria. As a result of their involvement, the sequence of base pairs within the promoter region is significant; the more similar the promoter region is to the consensus sequence, the tighter RNA polymerase will be able to bind. This binding contributes to the stability of elongation stage of transcription and overall results in more efficient functioning. Additionally, RNA polymerase and σ-factors are in limited supply within any given bacterial cell. Consequently, σ-factor binding to the promoter is affected by these limitations. All promoter regions contain sequences that are considered non-consensus and this helps to distribute σ-factors across the entirety of the genome. | 1 | Gene expression + Signal Transduction |
White etching cracks (WECs), first reported in 1996, are cracks that can form in the microstructure of bearing steel, leading to the development of a network of branched white cracks. They are usually observed in bearings that have failed due to rolling contact fatigue or accelerated rolling contact fatigue. These cracks can significantly shorten the reliability and operating life of bearings, both in the wind power industry and in several industrial applications.
The exact cause of WECs and their significance in rolling bearing failures have been the subject of much research and discussion. Ultimately, the formation of WECs appears to be influenced by a complex interplay between material, mechanical, and chemical factors, including hydrogen embrittlement, high stresses from sliding contact, inclusions, electrical currents, and temperature. They all also have all been identified as potential drivers of WECs. | 0 | Metallurgy |
Dimetcote is commonly used for steel corrosion resistance. It is generally reliable under humid or corrosive conditions. Because of this, Dimetcote is widely used in ships, power generation facilities, and marine, oil, and offshore structures. | 0 | Metallurgy |
The transcriptomes of stem cells and cancer cells are of particular interest to researchers who seek to understand the processes of cellular differentiation and carcinogenesis. A pipeline using RNA-seq or gene array data can be used to track genetic changes occurring in stem and precursor cells and requires at least three independent gene expression data from the former cell type and mature cells.
Analysis of the transcriptomes of human oocytes and embryos is used to understand the molecular mechanisms and signaling pathways controlling early embryonic development, and could theoretically be a powerful tool in making proper embryo selection in in vitro fertilisation. Analyses of the transcriptome content of the placenta in the first-trimester of pregnancy in in vitro fertilization and embryo transfer (IVT-ET) revealed differences in genetic expression which are associated with higher frequency of adverse perinatal outcomes. Such insight can be used to optimize the practice. Transcriptome analyses can also be used to optimize cryopreservation of oocytes, by lowering injuries associated with the process.
Transcriptomics is an emerging and continually growing field in biomarker discovery for use in assessing the safety of drugs or chemical risk assessment.
Transcriptomes may also be used to infer phylogenetic relationships among individuals or to detect evolutionary patterns of transcriptome conservation.
Transcriptome analyses were used to discover the incidence of antisense transcription, their role in gene expression through interaction with surrounding genes and their abundance in different chromosomes. RNA-seq was also used to show how RNA isoforms, transcripts stemming from the same gene but with different structures, can produce complex phenotypes from limited genomes. | 1 | Gene expression + Signal Transduction |
A single pit in a critical point can cause a great deal of damage. One example is the explosion in Guadalajara, Mexico on 22 April 1992, when gasoline fumes accumulated in sewers destroyed kilometers of streets. The vapors originated from a leak of gasoline through a single hole formed by corrosion between a steel gasoline pipe and a zinc-plated water pipe.
Firearms can also suffer from pitting, most notably in the bore of the barrel when corrosive ammunition is used and the barrel is not cleaned soon afterwards. Deformities in the bore caused by pitting can greatly reduce the firearm's accuracy. To reduce pitting in firearm bores, most modern firearms have a bore lined with chromium.
Pitting corrosion can also help initiate stress corrosion cracking, as happened when a single eyebar on the Silver Bridge in West Virginia, United States failed and killed 46 people on the bridge in December 1967.
In laboratories, pitting corrosion may damage equipment, reducing its performance or longevity. Fume hoods are of particular concern, as the material constitution of their ductwork must suit the primary effluent(s) intended for exhaust. If the chosen vent material is unsuitable for the primary effluent(s), consequent pitting corrosion will prevent the fume hood from effectively containing harmful airborne particles. | 0 | Metallurgy |
Synthetic regulatory elements such as enhancers promise to be a powerful tool to direct gene products to particular cell types in order to treat disease by activating beneficial genes or by halting aberrant cell states.
Since 2022, artificial intelligence and transfer learning strategies have led to a better understanding of the features of regulatory DNA sequences, the prediction, and the design of synthetic enhancers.
Building on work in cell culture, synthetic enhancers were successfully applied to entire living organisms in 2023. Using deep neural networks, scientists simulated the evolution of DNA sequences to analyze the emergence of features that underly enhancer function. This allowed the design and production of a range of functioning synthetic enhancers for different cell types of the fruit fly brain. A second approach trained artificial intelligence models on single-cell DNA accessibility data and transferred the learned models towards the prediction of enhancers for selected tissues in the fruit fly embryo. These enhancer prediction models were used to design synthetic enhancers for the nervous system, brain, muscle, epidermis and gut. | 1 | Gene expression + Signal Transduction |
Senapathy discovered that stop codons occur as key parts in every genetic element in eukaryotic genes. The table and figure show that the key parts of the core promoter elements, the lariat signal, the donor and acceptor splice signals, and the poly-A addition signal consist of one or more stop codons. This finding corroborates the split gene theory's claim that the underlying reason for the complete split gene paradigm is the origin of split genes from random DNA sequences, wherein random distribution of an extremely high frequency of stop codons were used by nature to define these genetic elements. | 1 | Gene expression + Signal Transduction |
Dendrites form in unary (one-component) systems as well as multi-component systems. The requirement is that the liquid (the molten material) be undercooled, aka supercooled, below the freezing point of the solid. Initially, a spherical solid nucleus grows in the undercooled melt. As the sphere grows, the spherical morphology becomes unstable and its shape becomes perturbed. The solid shape begins to express the preferred growth directions of the crystal. This growth direction may be due to anisotropy in the surface energy of the solid–liquid interface, or to the ease of attachment of atoms to the interface on different crystallographic planes, or both (for an example of the latter, see hopper crystal). In metallic systems, interface attachment kinetics is usually negligible (for non-negligible cases, see dendrite (crystal)). In metallic systems, the solid then attempts to minimize the area of those surfaces with the highest surface energy. The dendrite thus exhibits a sharper and sharper tip as it grows. If the anisotropy is large enough, the dendrite may present a faceted morphology. The microstructural length scale is determined by the interplay or balance between the surface energy and the temperature gradient (which drives the heat/solute diffusion) in the liquid at the interface.
As solidification proceeds, an increasing number of atoms lose their kinetic energy, making the process exothermic. For a pure material, latent heat is released at the solid–liquid interface so that the temperature remains constant until the melt has completely solidified. The growth rate of the resultant crystalline substance will depend on how fast this latent heat can be conducted away. A dendrite growing in an undercooled melt can be approximated as a parabolic needle-like crystal that grows in a shape-preserving manner at constant velocity. Nucleation and growth determine the grain size in equiaxed solidification while the competition between adjacent dendrites decides the primary spacing in columnar growth. Generally, if the melt is cooled slowly, nucleation of new crystals will be less than at large undercooling. The dendritic growth will result in dendrites of a large size. Conversely, a rapid cooling cycle with a large undercooling will increase the number of nuclei and thus reduce the size of the resulting dendrites (and often lead to small grains).
Smaller dendrites generally lead to higher ductility of the product. One application where dendritic growth and resulting material properties can be seen is the process of welding. The dendrites are also common in cast products, where they may become visible by etching of a polished specimen.
As dendrites develop further into the liquid metal, they get hotter because they continue to extract heat. If they get too hot, they will remelt. This remelting of the dendrites is called recalescence. Dendrites usually form under non-equilibrium conditions. | 0 | Metallurgy |
These are exclusively coal-fired processes, with the reducing gases generated inside the reduction vessel. The ore is charged with coal into a closed container. This is then heated until the oxygen present in the ore combines with the carbon before being discharged, mainly in the form of CO or CO2. This production of gas by heating a solid material means that the reactor belongs to the retort category.
The principle is an ancient one: in northern China, the shortage of charcoal led to the development of processes using hard coal before the 4th century. To avoid any contact between iron and sulfur, the brittle element provided by coal, China developed a process that involved placing iron ore in batteries of elongated tubular crucibles and covering them with a mass of coal, which was then burned. This process survived into the 20th century.
More recently, other historic processes have come to the fore, such as that of Adrien Chenot, operational in the 1850s in a number of plants in France and Spain. Successive improvements by Blair, Yutes, Renton, and Verdié are not significant. Among the processes developed is the HOGANAS process, perfected in 1908. Three small units are still operational (as of 2010). Not very productive, it is limited to the production of powdered iron, but as it is slow and operates in closed retorts, it easily achieves the purities required by powder metallurgy.
Other retort processes were developed, such as KINGLOR-METOR, perfected in 1973. Two small units were built in 1978 (closed) and 1981 (probably closed). | 0 | Metallurgy |
Using the Bessemer process, it took between 10 and 20 minutes to convert three to five tons of iron into steel — it would previously take at least a full day of heating, stirring and reheating to achieve this. | 0 | Metallurgy |
Nickel-based superalloys are used in load-bearing structures requiring the highest homologous temperature of any common alloy system (Tm = 0.9, or 90% of their melting point). Among the most demanding applications for a structural material are those in the hot sections of turbine engines (e.g. turbine blade). They comprise over 50% of the weight of advanced aircraft engines. The widespread use of superalloys in turbine engines coupled with the fact that the thermodynamic efficiency of turbine engines is a function of increasing turbine inlet temperatures has provided part of the motivation for increasing the maximum-use temperature of superalloys. From 1990-2020, turbine airfoil temperature capability increased on average by about 2.2 °C/year. Two major factors have made this increase possible:
* Processing techniques that improved alloy cleanliness (thus improving reliability) and/or enabled the production of tailored microstructures such as directionally solidified or single-crystal material.
* Alloy development resulting in higher temperature materials primarily through the additions of refractory elements such as Re, W, Ta, and Mo.
About 60% of the temperature increases related to advanced cooling, while 40% have resulted from material improvements. State-of-the-art turbine blade surface temperatures approach 1,150 C. The most severe stress and temperature combinations correspond to an average bulk metal temperature approaching 1,000 C..
Although Ni-based superalloys retain significant strength to 980 C, they tend to be susceptible to environmental attack because of the presence of reactive alloying elements. Surface attack includes oxidation, hot corrosion, and thermal fatigue. | 0 | Metallurgy |
There is an operational blacksmith shop with an operating line shaft setup powered by a 15-horsepower 1917 Mogul gasoline engine. During the show days, there are multiple forges lit, and multiple blacksmiths can be found working pieces of iron into many different things. | 0 | Metallurgy |
Rho-dependent transcription terminators require a large protein called a Rho factor which exhibits RNA helicase activity to disrupt the mRNA-DNA-RNA polymerase transcriptional complex. Rho-dependent terminators are found in bacteria and phages. The Rho-dependent terminator occurs downstream of translational stop codons and consists of an unstructured, cytosine-rich sequence on the mRNA known as a Rho utilization site (rut), and a downstream transcription stop point (tsp). The rut serves as a mRNA loading site and as an activator for Rho; activation enables Rho to efficiently hydrolyze ATP and translocate down the mRNA while it maintains contact with the rut site. Rho is able to catch up with the RNA polymerase because it is being stalled at the downstream tsp sites. Multiple different sequences can function as a tsp site. Contact between Rho and the RNA polymerase complex stimulates dissociation of the transcriptional complex through a mechanism involving allosteric effects of Rho on RNA polymerase. | 1 | Gene expression + Signal Transduction |
Metallurgists study the microscopic and macroscopic structure of metals using metallography, a technique invented by Henry Clifton Sorby.
In metallography, an alloy of interest is ground flat and polished to a mirror finish. The sample can then be etched to reveal the microstructure and macrostructure of the metal. The sample is then examined in an optical or electron microscope, and the image contrast provides details on the composition, mechanical properties, and processing history.
Crystallography, often using diffraction of x-rays or electrons, is another valuable tool available to the modern metallurgist. Crystallography allows identification of unknown materials and reveals the crystal structure of the sample. Quantitative crystallography can be used to calculate the amount of phases present as well as the degree of strain to which a sample has been subjected. | 0 | Metallurgy |
In plumbing systems fluxes are used to keep the mating surfaces clean during soldering operations. The fluxes often consist of corrosive chemicals such as ammonium chloride and zinc chloride in a binder such as petroleum jelly. If too much flux is applied to the joint then the excess will melt and run down the bore of a vertical tube or pool in the bottom of a horizontal tube. Where the bore of the tube is covered in a layer of flux it may be locally protected from corrosion but at the edges of the flux pits often initiate. If the tube is put into service in a water that supports Type 1 pitting then these pits will develop and eventually perforate the sides of the tube. | 0 | Metallurgy |
Copper is a fairly common element, with an estimated concentration of 50–70 ppm (0.005–0.007 percent) in Earths crust (1 kg of copper per 15–20 tons of crustal rock). A concentration of 60 ppm would multiply out to 1.66 quadrillion tonnes over the mass of the crust, or over 90 million years worth at the 2013 production rate of 18.3 MT per year. However, not all of it can be extracted profitably at the current level of technology and the current market value.
The USGS reported a current total reserve base of copper in potentially recoverable ores of 1.6 billion tonnes as of 2005, of which 950 million tonnes were considered economically recoverable. A 2013 global assessment identified "455 known deposits (with well-defined identified resources) that contain about 1.8 billion metric tons of copper", and predicted "a mean of 812 undiscovered deposits within the uppermost kilometer of the earth's surface" containing another 3.1 billion metric tons of copper "which represents about 180 times 2012 global copper production from all types of copper deposits." | 0 | Metallurgy |
China has long been considered the exception to the general use of bloomeries. The Chinese are thought to have skipped the bloomery process completely, starting with the blast furnace and the finery forge to produce wrought iron; by the fifth century BC, metalworkers in the southern state of Wu had invented the blast furnace and the means to both cast iron and to decarburize the carbon-rich pig iron produced in a blast furnace to a low-carbon, wrought iron-like material. Recent evidence, however, shows that bloomeries were used earlier in ancient China, migrating in from the west as early as 800 BC, before being supplanted by the locally developed blast furnace. Supporting this theory was the discovery of "more than ten" iron-digging implements found in the tomb of Duke Jing of Qin (d. 537 BCE), whose tomb is located in Fengxiang County, Shaanxi (a museum exists on the site today). | 0 | Metallurgy |
When a hot steel work-piece is quenched, the area in contact with the water immediately cools and its temperature equilibrates with the quenching medium. The inner depths of the material however, do not cool so rapidly, and in work-pieces that are large, the cooling rate may be slow enough to allow the austenite to transform fully into a structure other than martensite or bainite. This results in a work-piece that does not have the same crystal structure throughout its entire depth; with a softer core and harder "shell". The softer core is some combination of ferrite and cementite, such as pearlite.
The hardenability of ferrous alloys, i.e. steels, is a function of the carbon content and other alloying elements and the grain size of the austenite. The relative importance of the various alloying elements is calculated by finding the equivalent carbon content of the material.
The fluid used for quenching the material influences the cooling rate due to varying thermal conductivities and specific heats. Substances like brine and water cool the steel much more quickly than oil or air. If the fluid is agitated cooling occurs even more quickly. The geometry of the part also affects the cooling rate: of two samples of equal volume, the one with higher surface area will cool faster. | 0 | Metallurgy |
The shape memory effect (SME) occurs because a temperature-induced phase transformation reverses deformation, as shown in the previous hysteresis curve. Typically the martensitic phase is monoclinic or orthorhombic (B19' or [https://www.atomic-scale-physics.de/lattice/struk/b19.html B19]). Since these crystal structures do not have enough slip systems for easy dislocation motion, they deform by twinning—or rather, detwinning.
Martensite is thermodynamically favored at lower temperatures, while austenite ([https://www.atomic-scale-physics.de/lattice/struk/b2.html B2] cubic) is thermodynamically favored at higher temperatures. Since these structures have different lattice sizes and symmetry, cooling austenite into martensite introduces internal strain energy in the martensitic phase. To reduce this energy, the martensitic phase forms many twins—this is called "self-accommodating twinning" and is the twinning version of geometrically necessary dislocations. Since the shape memory alloy will be manufactured from a higher temperature and is usually engineered so that the martensitic phase is dominant at operating temperature to take advantage of the shape memory effect, SMAs "start" highly twinned.
When the martensite is loaded, these self-accommodating twins provide an easy path for deformation. Applied stresses will detwin the martensite, but all of the atoms stay in the same position relative to the nearby atoms—no atomic bonds are broken or reformed (as they would be by dislocation motion). Thus, when the temperature is raised and austenite becomes thermodynamically favored, all of the atoms rearrange to the B2 structure which happens to be the same macroscopic shape as the B19' pre-deformation shape. This phase transformation happens extremely quickly and gives SMAs their distinctive "snap".
Repeated use of the shape-memory effect may lead to a shift of the characteristic transformation temperatures (this effect is known as functional fatigue, as it is closely related with a change of microstructural and functional properties of the material). The maximum temperature at which SMAs can no longer be stress induced is called M, where the SMAs are permanently deformed. | 0 | Metallurgy |
There is direct evidence that the Romans mechanised at least part of the extraction processes. They used water power from water wheels for grinding grains and sawing timber or stone, for example. A set of sixteen such overshot wheels is still visible at Barbegal near Arles and dates from the 1st century AD or possibly earlier, the water being supplied by the main aqueduct to Arles. It is likely that the mills supplied flour for Arles and other towns locally. Multiple grain mills also existed on the Janiculum hill in Rome.
Ausonius attests the use of a water mill for sawing stone in his poem Mosella from the 4th century AD. They could easily have adapted the technology to crush ore using tilt hammers, and just such is mentioned by Pliny the Elder in his Naturalis Historia dating to about 75 AD, and there is evidence for the method from Dolaucothi in South Wales. The Roman gold mines developed from c. 75 AD. The methods survived into the medieval period, as described and illustrated by Georgius Agricola in his De re metallica.
They also used reverse overshot water-wheels for draining mines, the parts being prefabricated and numbered for ease of assembly. Multiple set of such wheels have been found in Spain at the Rio Tinto copper mines and a fragment of a wheel at Dolaucothi. An incomplete wheel from Spain is now on public show in the British Museum. | 0 | Metallurgy |
Cho et al. were the first who determined that clustered genes have the same expression levels. They identified transcripts that show cell-cycle dependent periodicity. Of those genes 25% was located in close proximity to other genes which were transcript in the same cell cycle. Cohen et al. (2000) also identified clusters of co-expressed genes.
Caron et al. (2001) made a human transcriptome map of 12 different tissues (cancer cells) and concluded that genes are not randomly distributed across the chromosomes. Instead, genes tend to cluster in groups of sometimes 39 genes in close proximity. Clusters were not only gene dense. They identified 27 clusters of genes with very high expression levels and called them RIDGEs. A common RIDGE counts 6 to 30 genes per centiray. However, there were great exceptions, 40 to 50% of the RIDGEs were not that gene dense; just like in yeast these RIDGEs were located in the telomere regions.
Lercher et al. (2002) pointed to some weaknesses in Caron's approach. Clusters of genes in close proximity and high transcription levels can easily been generated by tandem duplicates. Genes can generate duplicates of themselves which are incorporated in their neighborhood. These duplicates can either became a functional part of the pathway of their parent gene, or (because they are no longer favored by natural selection) gain deleterious mutations and turn into pseudogenes. Because these duplicates are false positives in the search for gene clusters they have to be excluded. Lercher excluded neighboring genes with high resemblance to each other, after that he searched with a sliding window for regions with 15 neighboring genes.
It was clear that gene dense regions existed. There was a striking correlation between gene density and a high CG content. Some clusters indeed had high expression levels. But most of the highly expressed regions consisted of housekeeping genes; genes that are highly expressed in all tissues because they code for basal mechanisms. Only a minority of the clusters contained genes that were restricted to specific tissues.
Versteeg et al. (2003) tried, with a better human genome map and better SAGE , to determine the characteristics of RIDGEs more specific. Overlapping genes were treated as one gene, and genes without introns were rejected as pseudogenes. They determined that RIDGEs are very gene dense, have a high gene expression, short introns, high SINE repeat density and low LINE repeat density. Clusters containing genes with very low transcription levels had characteristics that were the opposite of RIDGEs, therefore those clusters were called antiridges. LINE repeats are junk DNA which contains a cleavage site of endonuclease (TTTTA). Their scarcity in RIDGEs can be explained by the fact that natural selection favors the scarcity of LINE repeats in ORFs because their endonuclease sites can cause deleterious mutation to the genes. Why SINE repeats are abundant is not yet understood.
Versteeg et al. also concluded that, contrary to Lerchers analysis, the transcription levels of many genes in RIDGEs (for example a cluster on chromosome 9) can vary strongly between different tissues. Lee et al. (2003) analyzed the trend of gene clustering between different species. They compared Saccharomyces cerevisiae, Homo sapiens, Caenorhabditis elegans, Arabidopsis thaliana and Drosophila melanogaster, and found a degree of clustering, as fraction of genes in loose clusters, of respectively (37%), (50%), (74%), (52%) and (68%). They concluded that pathways of which the genes are clusters across many species are rare. They found seven universally clustered pathways: glycolysis, aminoacyl-tRNA biosynthesis, ATP synthase, DNA polymerase, hexachlorocyclohexane degradation, cyanoamino acid metabolism, and photosynthesis (ATP synthesis in non plant species). Not surprisingly these are basic cellular pathways.
Lee et al. used very diverse groups of animals. Within these groups clustering is conserved, for example the clustering motifs of Homo sapiens and Mus musculus are more or less the same.
Spellman and Rubin (2002) made a transcriptome map of Drosophila. Of all assayed genes 20% was clustered. Clusters consisted of 10 to 30 genes over a group size of about 100 kilobases. The members of the clusters were not functionally related and the location of clusters didn't correlate with know chromatin structures.
This study also showed that within clusters the expression levels of on average 15 genes was much the same across the many experimental conditions which were used. These similarities were so striking that the authors reasoned that the genes in the clusters are not individually regulated by their personal promoter but that changes in the chromatin structure were involved. A similar co-regulation pattern was published in the same year by Roy et al. (2002) in C. elegans.
Many genes which are grouped into clusters show the same expression profiles in human invasive ductal breast carcinomas. Roughly 20% of the genes show a correlation with their neighbors. Clusters of co-expressed genes were divided by regions with less correlation between genes. These clusters could cover an entire chromosome arm.
Contrary to previous discussed reports Johnidis et al. (2005) have discovered that (at least some) genes within clusters are not co-regulated. Aire is a transcription factor which has an up- and down-regulation effect on various genes. It functions in negative selection of thymocytes, which responds to the organisms own epitopes, by medullary cells.
The genes that were controlled by aire clustered. 53 of the genes most activated by aire had an aire-activated neighbor within 200 Kb or less, and 32 of the genes most repressed by aire had an aire-repressed neighbor within 200 Kb; this is less than expected by change. They did the same screening for the transcriptional regulator CIITA.
These transcription regulators didnt have the same effect on al genes in the same cluster. Genes that were activated and repressed or unaffected were sometimes present in the same cluster. In this case, its impossible that aire-regulated genes were clustered because they were all co-regulated.
So it is not very clear if domains are co-regulated or not. A very effective way to test this would be by insert synthetic genes into RIDGEs, antiridges and/or random places in the genome and determine their expression. Those expression levels must be compared to each other. Gierman et al. (2007) were the first who proved co-regulation using this approach. As an insertion construct they used a fluorescing GFP gene driven by the ubiquitously expressed human phosphoglycerate kinase (PGK) promoter. They integrated this construct in 90 different positions in the genome of human HEK293 cells. They found that the expression of the construct in Ridges was indeed higher than those inserted in antiridges (while all constructs have the same promoter).
They investigated if these differences in expressions were due to genes in the direct neighborhood of the constructs or by the domain as a whole. They found that constructs next to highly expressed genes were slightly more expressed than others. But when to enlarged the window size to the surrounding 49 genes (domain level) they saw that constructs located in domains with an overall high expression had a more than 2-fold higher expression then those located in domains with a low expression level.
They also checked if the construct was expressed at similar levels as neighboring genes, and if that tight co-expression was present solely within RIDGEs. They found that the expressions were highly correlated within RIDGEs, and almost absent near the end and outside the RIDGEs.
Previous observations and the research of Gierman et al. proved that the activity of a domain has great impact on the expression of the genes located in it. And the genes within a RIDGE are co-expressed. However the constructs used by Gierman et al. were regulated by al full-time active promoter. The genes of the research of Johnidis et al. were dependent of the present of the aire transcription factor. The strange expression of the aire regulated genes could partly have been caused by differences in expression and conformation of the aire transcription factor itself. | 1 | Gene expression + Signal Transduction |
Microarray data is often normalized within arrays to control for systematic biases in dye coupling and hybridization efficiencies, as well as other technical biases in the DNA probes and the print tip used to spot the array. By minimizing these systematic variations, true biological differences can be found. To determine whether normalization is needed, one can plot Cy5 (R) intensities against Cy3 (G) intensities and see whether the slope of the line is around 1. An improved method, which is basically a scaled, 45 degree rotation of the R vs. G plot is an MA-plot. The MA-plot is a plot of the distribution of the red/green intensity ratio (M) plotted by the average intensity (A). M and A are defined by the following equations.
M is, therefore, the binary logarithm of the intensity ratio (or difference between log intensities) and A is the average log intensity for a dot in the plot. MA plots are then used to visualize intensity-dependent ratio of raw microarray data (microarrays typically show a bias here, with higher A resulting in higher |M|, i.e. the brighter the spot the more likely an observed difference between sample and control). The MA plot puts the variable M on the y-axis and A on the x-axis and gives a quick overview of the distribution of the data.
In many microarray gene expression experiments, an underlying assumption is that most of the genes would not see any change in their expression; therefore, the majority of the points on the y-axis (M) would be located at 0, since log(1) is 0. If this is not the case, then a normalization method such as LOESS should be applied to the data before statistical analysis. (On the diagram below see the red line running below the zero mark before normalization, it should be straight. Since it is not straight, the data should be normalized. After being normalized, the red line is straight on the zero line and shows as pink/black.) | 1 | Gene expression + Signal Transduction |
Airless spray equipment used for Dimetcote should have a fluid tip with orifice no smaller than 0.019 inch (0.48), and the minimum level of pump ratio is 28:1. Some standard airless sprays such as Spee-Flo, Graco, Nordson-Bede, and DeVilbiss meet these requirements. | 0 | Metallurgy |
Thiosulfate ion is produced by the reaction of sulfite ion with elemental sulfur, and by incomplete oxidation of sulfides (e.g. pyrite oxidation). Sodium thiosulfate can be formed by disproportionation of sulfur dissolving in sodium hydroxide (similar to phosphorus). | 0 | Metallurgy |
The Manhès–David process is a refining process of the copper mattes, invented in 1880 by the French industrialist Pierre Manhès and his engineer . Inspired by the Bessemer process, it consists of the use of a converter to oxidise with air the undesirable chemical elements (mainly iron and sulfur) contained in the matte, to transform it into copper.
The quantity of the elements to be oxidized, as well as the low heat produced by the chemical reactions, lead to drastics modifications of the converter. Manhès and David designed it as a horizontal cylinder, with nozzles aligned from one end to the other. A few years later, the Americans engineers William H. Peirce and Elias Anton Cappelen Smith lined it with basic refractory materials, much more durable than that used by the French inventors. While this improvement does not alter the principles of the process, it eases its widespread use, accelerating the switchover of copper production from Britain to the United States.
At the beginning of the 21st century, the refine 90% of the copper mattes and is used in 60% of the nickel extracted. This converter, like the addition of pure oxygen, the automation of the running, the treatment of smoke and the increasing size of the tools, ensured the durability of the Manhès–David process, even if modern tools have little relationship with their ancestors. | 0 | Metallurgy |
These thermocouples are well-suited for measuring extremely high temperatures. Typical uses are hydrogen and inert atmospheres, as well as vacuum furnaces. They are not used in oxidizing environments at high temperatures because of embrittlement. A typical range is 0 to 2315 °C, which can be extended to 2760 °C in inert atmosphere and to 3000 °C for brief measurements.
Pure tungsten at high temperatures undergoes recrystallization and becomes brittle. Therefore, types C and D are preferred over type G in some applications.
In presence of water vapor at high temperature, tungsten reacts to form tungsten(VI) oxide, which volatilizes away, and hydrogen. Hydrogen then reacts with tungsten oxide, after which water is formed again. Such a "water cycle" can lead to erosion of the thermocouple and eventual failure. In high temperature vacuum applications, it is therefore desirable to avoid the presence of traces of water.
An alternative to tungsten/rhenium is tungsten/molybdenum, but the voltage–temperature response is weaker and has minimum at around 1000 K.
The thermocouple temperature is limited also by other materials used. For example beryllium oxide, a popular material for high temperature applications, tends to gain conductivity with temperature; a particular configuration of sensor had the insulation resistance dropping from a megaohm at 1000 K to 200 ohms at 2200 K. At high temperatures, the materials undergo chemical reaction. At 2700 K beryllium oxide slightly reacts with tungsten, tungsten-rhenium alloy, and tantalum; at 2600 K molybdenum reacts with BeO, tungsten does not react. BeO begins melting at about 2820 K, magnesium oxide at about 3020 K. | 0 | Metallurgy |
Single crystal growth starts with a seed crystal that is used to template growth of a larger crystal. The overall process is lengthy, and machining is necessary after the single crystal is grown. | 0 | Metallurgy |
Heat engines are not the most efficient ones, and with the use of bimetallic strips the efficiency of the heat engine is even lower as there is no chamber to contain the heat. Moreover, the bimetallic strips cannot produce strength in its moves, the reason why is that in order to achieve reasonables bendings (movements) both metallic strips have to be thin to make the difference between the expansion noticeable. So the uses for metallic strips in heat engines are mostly in simple toys that have been built to demonstrate how the principle can be used to drive a heat engine. | 0 | Metallurgy |
This family includes TGF-β1, TGF-β2, TGF-β3, and TGF-β5. They are involved in positively and negatively regulation of cell division, the formation of the extracellular matrix between cells, apoptosis, and embryogenesis. They bind to TGF-β type II receptor (TGFBRII).
TGF-β1 stimulates the synthesis of collagen and fibronectin and inhibits the degradation of the extracellular matrix. Ultimately, it increases the production of extracellular matrix by epithelial cells.
TGF-β proteins regulate epithelia by controlling where and when they branch to form kidney, lung, and salivary gland ducts. | 1 | Gene expression + Signal Transduction |
Several protein members of the BRCA1-associated genome surveillance complex (BASC) associate with RNA polymerase II and play a role in transcription.
The transcription factor TFIIH is involved in transcription initiation and DNA repair. MAT1 (for ménage à trois-1) is involved in the assembly of the CAK complex. CAK is a multisubunit protein that includes CDK7, cyclin H (CCNH), and MAT1. CAK is an essential component of the transcription factor TFIIH that is involved in transcription initiation and DNA repair.
The nucleotide excision repair (NER) pathway is a mechanism to repair damage to DNA. ERCC2 is involved in transcription-coupled NER and is an integral member of the basal transcription factor BTF2/TFIIH complex. ERCC3 is an ATP-dependent DNA helicase that functions in NER. It also is a subunit of basal transcription factor 2 (TFIIH) and, thus, functions in class II transcription. XPG (ERCC5) forms a stable complex with TFIIH, which is active in transcription and NER. ERCC6 encodes a DNA-binding protein that is important in transcription-coupled excision repair. ERCC8 interacts with Cockayne syndrome type B (CSB) protein, with p44 (GTF2H2), a subunit of the RNA polymerase II transcription factor IIH, and ERCC6. It is involved in transcription-coupled excision repair.
Higher error ratios in transcription by RNA polymerase II are observed in the presence of Mn compared to Mg. | 1 | Gene expression + Signal Transduction |
In metal processing, a reducing atmosphere is used in annealing ovens for relaxation of metal stresses without corroding the metal. A non-oxidizing gas, usually nitrogen or argon, is typically used as a carrier gas so that diluted amounts of reducing gases may be used. Typically, this is achieved through using the combustion products of fuels and tailoring the ratio of CO:CO. However, other common reducing atmospheres in the metal processing industries consist of dissociated ammonia, vacuum, and/or direct mixing of appropriately pure gases of N, Ar, and H.
A reducing atmosphere is also used to produce specific effects on ceramic wares being fired. A reduction atmosphere is produced in a fuel fired kiln by reducing the draft and depriving the kiln of oxygen. This diminished level of oxygen causes incomplete combustion of the fuel and raises the level of carbon inside the kiln. At high temperatures the carbon will bond with and remove the oxygen in the metal oxides used as colorants in the glazes. This loss of oxygen results in a change in the color of the glazes because it allows the metals in the glaze to be seen in an unoxidized form. A reduction atmosphere can also affect the color of the clay body. If iron is present in the clay body, as it is in most stoneware, then it will be affected by the reduction atmosphere as well.
In most commercial incinerators, exactly the same conditions are created to encourage the release of carbon bearing fumes. These fumes are then oxidized in reburn tunnels where oxygen is injected progressively. The exothermic oxidation reaction maintains the temperature of the reburn tunnels. This system allows lower temperatures to be employed in the incinerator section, where the solids are volumetrically reduced. | 0 | Metallurgy |
The complement component 1, q subcomponent-like 1 (or C1QL1) is encoded by a gene located at chromosome 17q21.31. It is a secreted protein and is 258 amino acids in length.
The protein is widely expressed but its expression is highest in the brain and may also be involved in regulation of motor control.
The pre-mRNA of this protein is subject to RNA editing. | 1 | Gene expression + Signal Transduction |
Pločnik (archaeological site) is located in Pločnik, Prokuplje village in the Toplica District of Serbia. A 120 hectare settlement belonging to the Neolithic Vinča culture existed on the site from 5500 BCE until it was destroyed by fire in 4700 BCE.
The site was first discovered during railway construction in 1927, but was investigated only sporadically until excavations carried out by the Prokuplje Museum the National Museum of Serbia began in 1996.
The Vinča houses at Pločnik had stoves and special holes specifically for rubbish, and the dead were buried in cemeteries. People slept on woollen mats and fur and made clothes of wool, flax and leather. The figurines found not only represent deities but many show the daily life of the inhabitants while crude pottery finds appear to have been made by children. Women are depicted in short tops and skirt wearing jewellery. A thermal well found near the settlement might be evidence of Europe's oldest spa. | 0 | Metallurgy |
Carbon steels which can successfully undergo heat-treatment have a carbon content in the range of 0.30–1.70% by weight. Trace impurities of various other elements can significantly affect the quality of the resulting steel. Trace amounts of sulfur in particular make the steel red-short, that is, brittle and crumbly at high working temperatures. Low-alloy carbon steel, such as A36 grade, contains about 0.05% sulfur and melt around . Manganese is often added to improve the hardenability of low-carbon steels. These additions turn the material into a low-alloy steel by some definitions, but AISI's definition of carbon steel allows up to 1.65% manganese by weight.
There are two types of higher carbon steels which are high carbon steel and the ultra high carbon steel. The reason for the limited use of high carbon steel is that it has extremely poor ductility and weldability and has a higher cost of production. The applications best suited for the high carbon steels is its use in the spring industry, farm industry, and in the production of wide range of high-strength wires. | 0 | Metallurgy |
The first production of zinc in quantity seems to have been in India starting from 12th century and later in China from 16th century. In India, zinc was produced at Zawar from the 12th to the 18th centuries, although some zinc artifacts appear to have been made during classical antiquity in Europe. The sphalerite ore found here was presumably converted to zinc oxide via roasting, although no archaeological evidence of this has been found. Smelting is thought to have been done in sealed cylindrical clay retorts which were packed with a mixture of roasted ore, dolomite, and an organic material, perhaps cow dung, and then placed vertically in a furnace and heated to around 1100 °C. Carbon monoxide produced by the charring of the organic material would have reduced the zinc oxide to zinc vapour, which then liquefied in a conical clay condenser at the bottom of the retort, dripping down into a collection vessel. Over the period 1400–1800, production is estimated to have been about 200 kg/day. Zinc was also smelted in China from the mid-sixteenth century on.
Large-scale zinc production in Europe began with William Champion, who patented a zinc distillation process in 1738. In Champion's process, zinc ore (in this case, the carbonate, ZnCO) was sealed in large reduction pots with charcoal and heated in a furnace. The zinc vapor then descended through an iron condensing pipe until reaching a water-filled vessel at the bottom. Champion set up his first zinc works in Bristol, England, but soon expanded to Warmley and by 1754 had built four zinc furnaces there. Although Champion succeeded in producing about 200 tons of zinc, his business plans were not successful and he was bankrupt by 1769. However, zinc smelting continued in this area until 1880.
Early European zinc production also took place in Silesia, in Carinthia, and in Liège, Belgium. In the Carinthian process, used in works established in 1798 by Bergrath Dillinger, a wood-fueled furnace heated a large number of small vertical retorts, and zinc vapor then dropped through a ceramic pipe into a common condensation chamber below. This process was out of use by 1840. The Belgian and Silesian processes both used horizontal retorts. In Silesia, Johann Ruhberg built a furnace to distill zinc in 1799, at first using pots but later changing to flat-bottomed retorts called "muffles", attached to horizontal tubes bent downwards in which the zinc condensed. The Silesian process eventually merged with the Belgian process. This process, developed by Jean-Jacques Daniel Dony, was introduced 1805–1810, and used retorts with a cylindrical cross-section. Condensers were horizontal clay tubes extending from the ends of the retorts. The merged "Belgo-Silesian" horizontal retort process was widely adopted in Europe by the third quarter of the 19th century, and later in the United States.
Experimental attempts to extract zinc via electrolysis begun in the 19th century, but the only commercially successful application before 1913 was a process, used in Great Britain and Austria, where zinc and chlorine were co-produced by electrolysis of an aqueous zinc chloride solution. The Anaconda Copper Company, at Anaconda, Montana, and the Consolidated Mining and Smelting Company, at Trail, British Columbia, both built successful electrolytic plants in 1915 using the currently used zinc sulfate process. This method has continued to grow in importance and in 1975 accounted for 68% of world zinc production.
The continuous vertical retort process was introduced in 1929 by the New Jersey Zinc Company. This process used a retort with silicon carbide walls, around 9 meters high and with a cross section of 2 by 0.3 meters. The walls of the retort were heated to 1300 °C and briquettes consisting of sintered zinc ore, coke, coal, and recycled material were fed into the top of the retort. Gaseous zinc was drawn off from the top of the column and, after a 20-hour journey through the retort, spent briquettes were removed from the bottom. To condense the gaseous zinc, the company first used a simple brick chamber with carborundum baffles, but efficiency was poor. During the 1940s a condenser was developed which condensed the zinc vapor on a spray of liquid zinc droplets, thrown up by an electrical impeller.
The electrothermic process, developed by the St. Joseph's Lead Company, was somewhat similar. The first commercial plant using this process was built in 1930 at the present site of Josephtown, Pennsylvania. The electrothermic furnace was a steel cylinder around 15 meters high and 2 meters in diameter, lined with firebrick. A mixture of sintered ore and coke was fed into the top of the furnace, and a current of 10,000–20,000 amperes, at a potential difference of 240 volts, was applied between carbon electrodes in the furnace, raising the temperature to 1200–1400 °C. An efficient condenser was devised for this process from 1931–1936; it consisted of a bath of liquid zinc which the exhaust gases were drawn through by suction. The zinc content of the gas stream was absorbed into the liquid bath.
The blast-furnace process was developed starting in 1943 at Avonmouth, England by the Imperial Smelting Corporation, which became part of Rio Tinto Zinc in 1968. It uses a spray of molten lead droplets to condense the zinc vapor. | 0 | Metallurgy |
The identification of synexpression groups has affected the way some scientists view evolutionary change in higher eukaryotes. Since groups of genes involved in the same biological process often share one or more common control elements, it has been suggested that the differential expression of these synexpression groups in different tissues of organisms can contribute to co-evolution tissues, organs, and appendages. Today it is commonly believed that it is not primarily the gene products themselves that evolve, but that it is the control networks for groups of genes that contribute most to the evolution of higher eukaryotes. | 1 | Gene expression + Signal Transduction |
The pachysolen tannophilus nuclear code (translation table 26) is a genetic code found in the ascomycete fungus Pachysolen tannophilus. | 1 | Gene expression + Signal Transduction |
The release of a neurotransmitter is triggered by the arrival of a nerve impulse (or action potential) and occurs through an unusually rapid process of cellular secretion (exocytosis). Within the presynaptic nerve terminal, vesicles containing neurotransmitter are localized near the synaptic membrane. The arriving action potential produces an influx of calcium ions through voltage-dependent, calcium-selective ion channels at the down stroke of the action potential (tail current). Calcium ions then bind to synaptotagmin proteins found within the membranes of the synaptic vesicles, allowing the vesicles to fuse with the presynaptic membrane. The fusion of a vesicle is a stochastic process, leading to frequent failure of synaptic transmission at the very small synapses that are typical for the central nervous system. Large chemical synapses (e.g. the neuromuscular junction), on the other hand, have a synaptic release probability, in effect, of 1. Vesicle fusion is driven by the action of a set of proteins in the presynaptic terminal known as SNAREs. As a whole, the protein complex or structure that mediates the docking and fusion of presynaptic vesicles is called the active zone. The membrane added by the fusion process is later retrieved by endocytosis and recycled for the formation of fresh neurotransmitter-filled vesicles.
An exception to the general trend of neurotransmitter release by vesicular fusion is found in the type II receptor cells of mammalian taste buds. Here the neurotransmitter ATP is released directly from the cytoplasm into the synaptic cleft via voltage gated channels. | 1 | Gene expression + Signal Transduction |
* A regularly updated repository of hundreds of computational analysis modules that support data preprocessing, gene expression analysis, proteomics, single nucleotide polymorphism (SNP) analysis, flow cytometry, and short-read sequencing.
* A programmatic interface that makes analysis modules available to computational biologists and developers from Python, Java, MATLAB, and R.
* The GenePattern Notebook Environment: Built on the Jupyter Notebook environment, GenePattern Notebook allows researchers to run GenePattern analyses within notebooks that interleave text, graphics, and executable code, creating a single "research narrative."
* GParc: Repository and community for GenePattern users to share and discuss their own GenePattern modules | 1 | Gene expression + Signal Transduction |
Negative regulators act to prevent transcription or translation. Examples such as cFLIP suppress cell death mechanisms leading to pathological disorders like cancer, and thus play a crucial role in drug resistance. Circumvention of such actors is a challenge in cancer therapy.
Negative regulators of cell death in cancer include cFLIP, Bcl family, Survivin, HSP, IAP, NF-κB, Akt, mTOR, and FADD. | 1 | Gene expression + Signal Transduction |
The ETS (Erythroblast Transformation Specific)family is divided into 12 subfamilies, which are listed below: | 1 | Gene expression + Signal Transduction |
By local transformations, the weld toe plastically deformed and solidified.
The depth of the aftertreatment track should be between 0.2 and 0.35 mm.
The undercut at the weld toe is no longer recognizable. | 0 | Metallurgy |
Non-ferrous metals were the first metals used by humans for metallurgy. Gold, silver and copper existed in their native crystalline yet metallic form. These metals, though rare, could be found in quantities sufficient to attract the attention of humans. Less susceptible to oxygen than most other metals, they can be found even in weathered outcroppings. Copper was the first metal to be forged; it was soft enough to be fashioned into various objects by cold forging and could be melted in a crucible. Gold, silver and copper replaced some of the functions of other resources, such as wood and stone, owing to their ability to be shaped into various forms for different uses. Due to their rarity, these gold, silver and copper artifacts were treated as luxury items and handled with great care. The use of copper also heralded the transition from the Stone Age to the Copper Age. The Bronze Age, which succeeded the Copper Age, was again heralded by the invention of bronze, an alloy of copper with the non-ferrous metal tin. | 0 | Metallurgy |
The lac repressor (LacI) is a DNA-binding protein that inhibits the expression of genes coding for proteins involved in the metabolism of lactose in bacteria. These genes are repressed when lactose is not available to the cell, ensuring that the bacterium only invests energy in the production of machinery necessary for uptake and utilization of lactose when lactose is present. When lactose becomes available, it is firstly converted into allolactose by β-Galactosidase (lacZ) in bacteria. The DNA binding ability of lac repressor bound with allolactose is inhibited due to allosteric regulation, thereby genes coding for proteins involved in lactose uptake and utilization can be expressed. | 1 | Gene expression + Signal Transduction |
Heatwork is the combined effect of temperature and time. It is important to several industries:
*Ceramics
*Glass and metal annealing
*Metal heat treating
Pyrometric devices can be used to gauge heat work as they deform or contract due to heatwork to produce temperature equivalents. Within tolerances, firing can be undertaken at lower temperatures for a longer period to achieve comparable results. When the amount of heatwork of two firings is the same, the pieces may look identical, but there may be differences not visible, such as mechanical strength and microstructure. Heatwork is taught in material science courses, but is not a precise measurement or a valid scientific concept. | 0 | Metallurgy |
Scientists at the CSIRO conducted small-scale test work on copper sulfide concentrate in 1979, using the CSIRO's 50 kg Sirosmelt test rig. These trials included producing copper matte containing 40–52% copper and, in some cases, converting the matte to produce blister copper.
The results of this work were sufficiently encouraging that MIM in 1983 undertook its own copper smelting test work program using its 120 kg/h test rig, which had by then been rerated to 250 kg/h. It was found that the process was easy to control and that copper loss to slag was low. It was also learned that the process could easily recover copper from copper converter slag concentrate, of which there was a large stockpile at Mount Isa. | 0 | Metallurgy |
Transposons and retrotransposons are mobile genetic elements. Retrotransposon repeated sequences, which include long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), account for a large proportion of the genomic sequences in many species. Alu sequences, classified as a short interspersed nuclear element, are the most abundant mobile elements in the human genome. Some examples have been found of SINEs exerting transcriptional control of some protein-encoding genes.
Endogenous retrovirus sequences are the product of reverse transcription of retrovirus genomes into the genomes of germ cells. Mutation within these retro-transcribed sequences can inactivate the viral genome.
Over 8% of the human genome is made up of (mostly decayed) endogenous retrovirus sequences, as part of the over 42% fraction that is recognizably derived of retrotransposons, while another 3% can be identified to be the remains of DNA transposons. Much of the remaining half of the genome that is currently without an explained origin is expected to have found its origin in transposable elements that were active so long ago (> 200 million years) that random mutations have rendered them unrecognizable. Genome size variation in at least two kinds of plants is mostly the result of retrotransposon sequences. | 1 | Gene expression + Signal Transduction |
The objectives of the European Coil Coating Association are described in the association's statutes and rules of procedure:
* Setting quality performance standards and developing test methods
* Spreading the benefits of coil and/or sheet coated metal with particular emphasis on environmental, cost and quality benefits
* Stimulating product, process, application and market developments
* Increasing the awareness of coil and/or sheet-coated metal through professional marketing and by organising educational training programmes for non-users
* Creating an industry network and forum for the development and exchange of ideas
* Representation of the Industry in its contacts with Public Officials and Public Authorities
* Providing liaison with other Trade Associations and Professional Bodies. | 0 | Metallurgy |
*Bio: Shortened form of Biology; refers to usage of bacteria.
*Hydro: Term referring to the usage of water; process occurs in aqueous environments
*Metallurgy: A process involving the separating and refining of metals from other substances;
*Bioleaching: Using biological agents (bacteria) to extract metals or soils; general term used to encompass all forms biotechnological forms of extraction (hydrometallurgy, biohydrometallurgy, biomining, etc) | 0 | Metallurgy |
Subsets and Splits