text
stringlengths 105
13.7k
| label
int64 0
1
| label_text
stringclasses 2
values |
|---|---|---|
The yield strength anomaly is exploited in the design of gas turbines and jet engines that operate at high temperatures, where the materials used are selected based on their paramount yield and creep resistance. Superalloys can withstand high temperature loads far beyond the capabilities of steels and other alloys, and allow operation at higher temperatures, which improves efficiency. | 0 | Metallurgy |
For classical silencers, the signaling pathway is relatively simple. Since repression is active, silencer elements target the assembly of GTFs, necessary for transcription of the gene. These silencer elements are mostly located upstream of the gene and can vary between short and long distances. For long-range silencers, it has been observed that the DNA will form a loop in order to bring the silencer closer to the promoter and loop out the interfering DNA. Silencers also target helicase sites in the DNA that are rich in adenine and thymine (AT) and prone to unwinding the DNA, allowing room to initiate transcription. The inhibited helicase activity leads to the inhibition of transcription. This is commonly seen in the human thyrotropin-β gene promoter. NREs can induce a bend in the promoter region to block interactions, as seen when an NRE binds to Yin-Yang 1 (YY1), and flank regulatory signals or promoter regions as well. When the silencer region is located within an intron, there can be two types of repressions. First, there can be a physical blockage of a splice site. Second, there can be a bend in the DNA that will inhibit RNA processing.
When located in the exon or the untranslated region, the silencer will mainly be classical or position-dependent. However, these silencers can carry out their activity prior to transcription. Most silencers are constitutively expressed in organisms, only allowing activation of a gene by either inhibiting the silencer or by activating an enhancer region. The best example of this is the Neuronal-Restrictive Silencer Factor (NRSF) that is produced by the REST gene. The REST gene produces NRSF in order to repress the transcription of neuronal genes that are essential for localization of neuronal tissue. When a silencer represses REST, NRSF is also inhibited, allowing for the transcription of neuronal genes. | 1 | Gene expression + Signal Transduction |
*Vibration - either sinusoidal vibration or gyratory vibration.
**Sinusoidal Vibration occurs at an angled plane relative to the horizontal. The vibration is in a wave pattern determined by frequency and amplitude.
**Gyratory Vibration occurs at near level plane at low angles in a reciprocating side to side motion.
*Gravity - This physical interaction is after material is thrown from the screen causing it to fall to a lower level. Gravity also pulls the particles through the screen media.
*Density - The density of the material relates to material stratification.
*Electrostatic Force - This force applies to screening when particles are extremely dry or is wet. | 0 | Metallurgy |
A receptor activated solely by a synthetic ligand (RASSL) or designer receptor exclusively activated by designer drugs (DREADD), is a class of artificially engineered protein receptors used in the field of chemogenetics which are selectively activated by certain ligands. They are used in biomedical research, in particular in neuroscience to manipulate the activity of neurons.
Originally differentiated by the approach used to engineer them, RASSLs and DREADDs are often used interchangeably now to represent an engineered receptor-ligand system. These systems typically utilize G protein-coupled receptors (GPCR) engineered to respond exclusively to synthetic ligands, like clozapine N-oxide (CNO), and not to endogenous ligands. Several types of these receptors exists, derived from muscarinic or κ-opioid receptors. | 1 | Gene expression + Signal Transduction |
Response regulator proteins typically consist of a receiver domain and one or more effector domains, although in some cases they possess only a receiver domain and exert their effects through protein-protein interactions. In two-component signaling, a histidine kinase responds to environmental changes by autophosphorylation on a histidine residue, following which the response regulator receiver domain catalyzes transfer of the phosphate group to its own recipient aspartate residue. This induces a conformational change that alters the function of the effector domains, usually resulting in increased transcription of target genes. The mechanisms by which this occurs are diverse and include allosteric activation of the effector domain or oligomerization of phosphorylated response regulators. In a common variation on this theme, called a phosphorelay, a hybrid histidine kinase possesses its own receiver domain, and a histidine phosphotransfer protein performs the final transfer to a response regulator.
In many cases, histidine kinases are bifunctional and also serve as phosphatases, catalyzing the removal of phosphate from response regulator aspartate residues, such that the signal transduced by the response regulator reflects the balance between kinase and phosphatase activity. Many response regulators are also capable of autodephosphorylation, which occurs on a wide range of time scales. In addition, phosphoaspartate is relatively chemically unstable and may be hydrolyzed non-enzymatically.
Histidine kinases are highly specific for their cognate response regulators; there is very little cross-talk between different two-component signaling systems in the same cell. | 1 | Gene expression + Signal Transduction |
Much gold jewelry is produced by casting, with little or no cold working; which, depending on the alloy grade, may leave the metal relatively soft and bendable. However, a jeweler may intentionally use work hardening to strengthen wearable objects that are exposed to stress, such as rings. | 0 | Metallurgy |
Aratashen (, also Romanized as Arratashen; also, Artashen; until 1978 Zeyva Hayi – meaning "Armenian Zeyva", Zeyva, Bol’shaya Zeyva and Nerkin-Zeyva) is a town in the Armavir Province of Armenia. It is located on the Ararat Plain. | 0 | Metallurgy |
A conceptual breakthrough of Jacob and Monod was to recognize the distinction between regulatory substances and sites where they act to change gene expression. A former soldier, Jacob used the analogy of a bomber that would release its lethal cargo upon receipt of a special radio transmission or signal. A working system requires both a ground transmitter and a receiver in the airplane. Now, suppose that the usual transmitter is broken. This system can be made to work by introduction of a second, functional transmitter. In contrast, he said, consider a bomber with a defective receiver. The behavior of this bomber cannot be changed by introduction of a second, functional aeroplane.
To analyze regulatory mutants of the lac operon, Jacob developed a system by which a second copy of the lac genes (lacI with its promoter, and lacZYA with promoter and operator) could be introduced into a single cell. A culture of such bacteria, which are diploid for the lac genes but otherwise normal, is then tested for the regulatory phenotype. In particular, it is determined whether LacZ and LacY are made even in the absence of IPTG (due to the lactose repressor produced by the mutant gene being non-functional). This experiment, in which genes or gene clusters are tested pairwise, is called a complementation test.
This test is illustrated in the figure (lacA is omitted for simplicity). First, certain haploid states are shown (i.e. the cell carries only a single copy of the lac genes). Panel (a) shows repression, (b) shows induction by IPTG, and (c) and (d) show the effect of a mutation to the lacI gene or to the operator, respectively. In panel (e) the complementation test for repressor is shown. If one copy of the lac genes carries a mutation in lacI, but the second copy is wild type for lacI, the resulting phenotype is normal—but lacZ is expressed when exposed to inducer IPTG. Mutations affecting repressor are said to be recessive to wild type (and that wild type is dominant), and this is explained by the fact that repressor is a small protein which can diffuse in the cell. The copy of the lac operon adjacent to the defective lacI gene is effectively shut off by protein produced from the second copy of lacI.
If the same experiment is carried out using an operator mutation, a different result is obtained (panel (f)). The phenotype of a cell carrying one mutant and one wild type operator site is that LacZ and LacY are produced even in the absence of the inducer IPTG; because the damaged operator site, does not permit binding of the repressor to inhibit transcription of the structural genes. The operator mutation is dominant. When the operator site where repressor must bind is damaged by mutation, the presence of a second functional site in the same cell makes no difference to expression of genes controlled by the mutant site.
A more sophisticated version of this experiment uses marked operons to distinguish between the two copies of the lac genes and show that the unregulated structural gene(s) is(are) the one(s) next to the mutant operator (panel (g). For example, suppose that one copy is marked by a mutation inactivating lacZ so that it can only produce the LacY protein, while the second copy carries a mutation affecting lacY and can only produce LacZ. In this version, only the copy of the lac operon that is adjacent to the mutant operator is expressed without IPTG. We say that the operator mutation is cis-dominant, it is dominant to wild type but affects only the copy of the operon which is immediately adjacent to it.
This explanation is misleading in an important sense, because it proceeds from a description of the experiment and then explains the results in terms of a model. But in fact, it is often true that the model comes first, and an experiment is fashioned specifically to test the model. Jacob and Monod first imagined that there must be a site in DNA with the properties of the operator, and then designed their complementation tests to show this.
The dominance of operator mutants also suggests a procedure to select them specifically. If regulatory mutants are selected from a culture of wild type using phenyl-Gal, as described above, operator mutations are rare compared to repressor mutants because the target-size is so small. But if instead we start with a strain which carries two copies of the whole lac region (that is diploid for lac), the repressor mutations (which still occur) are not recovered because complementation by the second, wild type lacI gene confers a wild type phenotype. In contrast, mutation of one copy of the operator confers a mutant phenotype because it is dominant to the second, wild type copy. | 1 | Gene expression + Signal Transduction |
Because BIK1 is a possible regulator of the FLS2-BAK1 complex, it is speculated that in vitro, BAK1 phosphorylates BIK1, which then phosphorylates both FLS2 and BAK1. However, in vivo, BIK1 is not phosphorylated until about 5-10 minutes after the addition of FS2, and the peak phosphorylation occurs just after the phosphorylation of the FS2-BAK1 complex. It is speculated that BIK1 activation might be enhanced through transphosphorylation by BAK1 rather than by FLS2 because FLS2 more likely serves as a scaffold protein for the arrangement of the BAK1-FLS2 complex. This hypothesis will require more testing in vivo. Research has shown that BIK1 and BAK1 are signaling partners for the flagellin receptor FLS2 and that the three together initiate defense response. However, BIK1 and BAK1 phosphorylate different residues of the FLS2 receptor with the exception of only a select few. This suggests that both BAK1 and BIK1 play unique roles in defense response by a series of phosphorylation reactions with one another and the flagellin receptor FLS2. | 1 | Gene expression + Signal Transduction |
Only with the Incas would metals really come into practical use. At Machu Picchu and other sites, metal was used for bolas, plumb bobs, chisels, gravers, pry bars, tweezers, needles, plates, fish hooks, spatulas, ladles, knives (tumi), bells, breastplates, lime spoons, mace heads, ear spools, bowls, cloak pins (tupus), axes, and foot plow adzes.
Nonetheless, they remained materials through which to display wealth and status. The characteristic importance placed on colour, which had led to some of the earlier developments, was still present (sun/moon association with gold/silver). Metals other than gold also had an intrinsic value, with axe pieces being of particular note in this regard. With the spread of metal tools by the Incas, it is thought possible that a more Old World use of metals would have become more common. In any case, as Bruhns notes, "[b]ronze can be seen as an expensive substitute for the equally efficient stone". However, sediment research in Bolivia has revealed that metals such as silver were smelted on a very large scale, thousands of tons, from late Tiwanaku to Inca times (1000–1530 CE), which suggests that the paucity of metal (particularly precious metal) at Inca sites is more likely caused by Spanish acquisition and export than by limited pre-colonial use.
It has been claimed that the Inca Empire expanded into Diaguita lands in what is now north-central Chile because of its mineral wealth, but that view is rejected by some scholars.
Further, an additional possibility is that the Incas invaded the relatively well-populated Eastern Diaguita valleys (present-day Argentina) to obtain labor to send to Chilean mining districts. The Incas influenced Diaguitas, who adopted Incan metalworking techniques.
Farther south in Chile, Mapuche tribes within or near the Incan Empire paid tributes in gold. Incan yanakuna are believed by archaeologists Tom Dillehay and Américo Gordon to have extracted gold south of the Incan frontier in free Mapuche territory. Following that thought, the main motive for Incan expansion into Mapuche territory would have been to access gold mines.
Among the Mapuche people of central and south-central Chile, gold had an important cultural significance that predates Inca contact.
At the time of the Spanish conquest of Chile, Mapuches are reported by various chroniclers to use gold ornaments. According to historian Osvaldo Silva gold ornaments of the Mapuche of the Concepción area evidence some kind of interaction between the Mapuche and the Inca that may have been trade, gifts, or spoils of war taken from a defeated Inca army.
Pre-Hispanic Mapuche tools are known to have been relatively simple and made of wood and stone, but a few of them were actually made of copper and bronze. | 0 | Metallurgy |
There are three main categories for triggering the release of sigmas factors from anti-sigma factors: partner switching, direct signaling, and a mechanism regulated by proteolysis.
The partner-switching mechanism is commonly found in Gram-positive bacteria. It consists of four key players: a sigma factor, an anti-sigma factor, an anti-anti-sigma factor, and an input phosphatase complex. A cell that is not under stress has an anti-sigma factor that is bound to the sigma factor on the gene and keeps it inactive. In times of stress, a phosphatase complex dephosphorylates the anti-sigma factor, allowing the anti-sigma factor to switch partners and bind to the anti-anti-sigma factor. This frees the sigma factors to activate the gene. Environmental stressors, such as heat, often activate this mechanism.
The direct signaling mechanism is as it sounds: the anti-sigma factor binds to a signal, which causes conformation changes in the structure of the anti-sigma factors, resulting in the release of the sigma factors.
The regulated intramembrane proteolysis (RIP) mechanism allows signal transduction across membranes. This mechanism is often used to regulate ECF sigma factors. The mechanism involves two sequential cleavages, the first being an external cleavage of membrane-traversing anti-sigma factor and the second cleavage of the anti-sigma factors in the membrane's plane, resulting in a free cytoplasmic domain. | 1 | Gene expression + Signal Transduction |
The same way that RNA silencing regulates downstream target mRNAs, RNA silencing itself is regulated. For example, silencing signals get spread between cells by a group of enzymes called RdRPs (RNA-dependent RNA polymerases) or RDRs. | 1 | Gene expression + Signal Transduction |
Stress signals can cause protein kinases, known as EIF-2 kinases, to phosphorylate the α subunit of a protein complex called translation initiation factor 2 (eIF2), resulting in the gene ATF4 being turned on, which will further affect gene expression. eIF2 consists of three subunits: eIF2α, eIF2β and eIF2γ. eIF2α contains two binding sites, one for phosphorylation and one for RNA binding. The kinases work to phosphorylate serine 51 on the α subunit, which is a reversible action. In a cell experiencing normal conditions, eIF2 aids in the initiation of mRNA translation and recognizing the AUG start codon. However, once eIF2α is phosphorylated, the complex’s activity reduces, causing reduction in translation initiation and protein synthesis, while promoting expression of the ATF4 gene. | 1 | Gene expression + Signal Transduction |
Fretting in Aluminium causes black debris to be present in the contact area due to the fine oxide particles. | 0 | Metallurgy |
CAF-1 is required for the spatial organization and epigenetic marking of heterochromatin domains in pluripotent embryonic cells, creating a cellular memory of somatic cell identity during cellular differentiation.
Cells resembling 2-cell-stage mouse embryos (totipotent cells) can be induced in vitro through downregulation of the chromatin-assembly activity of CAF-1 in embryonic stem cells.
CAF-1 forms a deadenylase complex with CCR4-Not, which should not be confused with the unrelated CCR4. The CAF-1/CCR4-Not complex cooperates with the release factor eRF3 and PABPC1 to shorten the poly(A) tail of mRNA during translation. | 1 | Gene expression + Signal Transduction |
Volatilizing roasting, involves oxidation at elevated temperatures of the ores, to eliminate impurity elements in the form of their volatile oxides. Examples of such volatile oxides include AsO, SbO, ZnO and sulfur oxides. Careful control of the oxygen content in the roaster is necessary, as excessive oxidation can form non-volatile oxides. | 0 | Metallurgy |
The primary role of CTCF is thought to be in regulating the 3D structure of chromatin. CTCF binds together strands of DNA, thus forming chromatin loops, and anchors DNA to cellular structures like the nuclear lamina. It also defines the boundaries between active and heterochromatic DNA.
Since the 3D structure of DNA influences the regulation of genes, CTCF's activity influences the expression of genes. CTCF is thought to be a primary part of the activity of insulators, sequences that block the interaction between enhancers and promoters. CTCF binding has also been both shown to promote and repress gene expression. It is unknown whether CTCF affects gene expression solely through its looping activity, or if it has some other, unknown, activity. In a recent study, it has been shown that, in addition to demarcating TADs, CTCF mediates promoter–enhancer loops, often located in promoter-proximal regions, to facilitate the promoter–enhancer interactions within one TAD. This is in line with the concept that a subpopulation of CTCF associates with the RNA polymerase II (Pol II) protein complex to activate transcription. It is likely that CTCF helps to bridge the transcription factor-bound enhancers to transcription start site-proximal regulatory elements and to initiate transcription by interacting with Pol II, thus supporting a role of CTCF in facilitating contacts between transcription regulatory sequences. This model has been demonstrated by the previous work on the beta-globin locus. | 1 | Gene expression + Signal Transduction |
Several domains of PCAF can act independently or in unison to enable its functions. PCAF has separate acetyltransferase and E3 ubiquitin ligase domains as well as a bromodomain for interaction with other proteins. PCAF also possesses sites for its own acetylation and ubiquitination. | 1 | Gene expression + Signal Transduction |
Mineral processing and extraction of metals are very energy-intensive processes, which are not exempted of producing large volumes of solid residues and wastewater, which also require energy to be further treated and disposed. Moreover, as the demand for metals increases, the metallurgical industry must rely on sources of materials with lower metal contents both from a primary (e.g., mineral ores) and/or secondary (e.g., slags, tailings, municipal waste) raw materials. Consequently, mining activities and waste recycling must evolve towards the development of more selective, efficient and environmentally friendly mineral and metal processing routes.
Mineral processing operations are needed firstly to concentrate the mineral phases of interest and reject the unwanted material physical or chemically associated to a defined raw material. The process, however, demand about 30 GJ/tonne of metal, which accounts about 29% of the total energy spent on mining in the USA. Meanwhile, pyrometallurgy is a significant producer of greenhouse gas emissions and harmful flue dust. Hydrometallurgy entails the consumption of large volumes of lixiviants such as HSO, HCl, KCN, NaCN which have poor selectivity. Moreover, despite the environmental concern and the use restriction imposed by some countries, cyanidation is still considered the prime process technology to recover gold from ores. Mercury is also used by artisanal miners in less economically developed countries to concentrate gold and silver from minerals, despite its obvious toxicity. Bio-hydro-metallurgy make use of living organisms, such as bacteria and fungi, and although this method demands only the input of and from the atmosphere, it requires low solid-to-liquid ratios and long contact times, which significantly reduces space-time yields.
Ionometallurgy makes use of non-aqueous ionic solvents such ionic liquids (ILs) and deep eutectic solvents (DESs), which allows the development of closed-loop flow sheet to effectively recover metals by, for instance, integrating the metallurgical unit operations of leaching and electrowinning. It allows to process metals at moderate temperatures in a non-aqueous environment which allows controlling metal speciation, tolerates impurities and at the same time exhibits suitable solubilities and current efficiencies. This simplify conventional processing routes and allows a substantial reduction in the size of a metal processing plant. | 0 | Metallurgy |
cAMP was discovered by Earl Sutherland and Ted Rall in the mid 1950s. cAMP is considered a secondary messenger along with Ca. Sutherland won the Nobel Prize in 1971 for his discovery of the mechanism of action of epinephrine in glycogenolysis, that requires cAMP as secondary messenger. | 1 | Gene expression + Signal Transduction |
The invention and widespread application of hydraulic mining, namely hushing and ground-sluicing, aided by the ability of the Romans to plan and execute mining operations on a large scale, allowed various base and precious metals to be extracted on a proto-industrial scale only rarely matched until the Industrial Revolution.
The most common fuel by far for smelting and forging operations, as well as heating purposes, was wood and particularly charcoal, which is nearly twice as efficient. In addition, coal was mined in some regions to a fairly large extent: almost all major coalfields in Roman Britain were exploited by the late 2nd century AD, and a lively trade along the English North Sea coast developed, which extended to the continental Rhineland, where bituminous coal was already used for the smelting of iron ore. The annual iron production at Populonia alone accounted for an estimated 2,000 to 10,000 tons. | 0 | Metallurgy |
Calcite rafts were first observed by Allison in 1923 on solution drops attached to concrete derived straw stalactites, and later by Ver Steeg. When the drip rate is ≥5 minutes between drops, calcium carbonate will have precipitated on the solution drop surface (at the end of a stalactite) to form calcite rafts visible to the naked eye (up to 0.5 mm across). If the drip rate is greater than ≈12 minutes between drops, and there is very little air movement, these rafts may join up and become a latticework of calcite rafts covering the drop surface. Significant air movement will cause the rafts to become scattered and spin turbulently around the drops surface. This turbulent movement of calcite rafts can cause some to shear off the drops surface tension and be pushed onto the outside of the straw stalactite, thus increasing the outside diameter and creating minute irregularities. | 0 | Metallurgy |
* Vg1 Family
* Activin Family
** Involved in embryogenesis and osteogenesis
** Regulate insulin and pituitary, gonadal, and hypothalamic hormones
** Nerve cell survival factors
**3 Activins: Activin A, Activin B and Activin AB.
* Glial-Derived Neurotrophic Factor (GDNF)
** Needed for kidney and enteric neuron differentiation
* Müllerian Inhibitory Factor
** Involved in mammalian sex determination
* Nodal
** Binds to Activin A Type 2B receptor
** Forms receptor complex with Activin A Type 1B receptor or with Activin A Type 1C receptor.
*Growth and differentiation factors (GDFs) | 1 | Gene expression + Signal Transduction |
Before being taken to the ingenio (amalgamation refinery), excess material would be broken off of the silver ore. At the refiner, it was ground to a fine sand (harina) by an arrastra or stamp mill, which consisted of a rotating shaft fitted with heavy iron stamps that crushed the ore against a mortar block. The harina was then placed in heaps of 2,000 lbs or more, to which was added salt, water, magistral (essentially an impure form of copper sulfate, CuSO), and mercury. This was then mixed by bare-legged Indian laborers or by horses or mules and spread in a 1-to-2-foot-thick (0.30 to 0.61 m) layer in a patio (a shallow-walled, open enclosure). After six to eight weeks of mixing and soaking in the sun, a complex reaction converted the silver to native metal, which formed an amalgam with the mercury. The mixture was then washed and strained through a canvas bag before being placed into a hooded oven. Heating this amalgam vaporized the mercury, leaving the silver. The mercury vapor would then condense on the cooled hood, where it could be collected and reused. The amount of salt and copper sulfate varied from one-quarter to ten pounds of one or the other, or both, per ton of ore treated. The decision of how much of each ingredient to add, how much mixing was needed, and when to halt the process depended on the skill of an (English: quicksilver man). The loss of mercury in amalgamation processes is generally one to two times the weight of silver recovered.
The patio process was the first form of amalgamation. However, it is unclear whether this process or a similar process—in which amalgamation occurred in heated vats rather than open patios—was the predominant form of amalgamation in New Spain, as the earliest known illustration of the patio process dates from 1761. There is substantial evidence that both processes were used from an early date in New Spain, while open patios were never adopted in Peru. Instead, Andean refiners placed milled ore in stone tanks vaulted over a fire, which helped accelerate amalgamation by mitigating the bitterly cold temperatures at the high elevation of the Andean mines. Both processes required that ore be crushed and refiners quickly established mills to process ore once amalgamation was introduced. Water mills were common in the Andes, powered by man-made dams, while in New Spain, where water was relatively scarce, mills were often powered by horses or other draft animals.
Due to amalgamation's reliance upon mercury, an expansion of mercury production was central to the expansion of silver production. A key source of mercury was at Huancavelica, Peru, where vast deposits were discovered in 1563. Additional mercury was sourced from Almadén, Spain, and Idrija in present-day Slovenia. From shortly after the invention of mercury amalgamation to the end of the colonial period, the Spanish crown maintained a monopoly on mercury production and distribution, ensuring a steady supply of royal income. Fluctuations in mercury prices generally resulted in corresponding increases and decreases in silver production. Crown control over these prices could be used to intentionally depress or stimulate silver production in Spanish colonies. | 0 | Metallurgy |
Learning and memory have levels of permanence, differing from other mental processes such as thought, language, and consciousness, which are temporary in nature. Learning and memory can be either accumulated slowly (multiplication tables) or rapidly (touching a hot stove), but once attained, can be recalled into conscious use for a long time. Rats subjected to one instance of contextual fear conditioning create an especially strong long-term memory. At 24 hours after training, 9.17% of the genes in the genomes of rat hippocampus neurons were found to be differentially methylated. This included more than 2,000 differentially methylated genes at 24 hours after training, with over 500 genes being demethylated. Similar results to that in the rat hippocampus were also obtained in mice with contextual fear conditioning.
The hippocampus region of the brain is where contextual fear memories are first stored (see Figure), but this storage is transient and does not remain in the hippocampus. In rats contextual fear conditioning is abolished when the hippocampus is subjected to hippocampectomy just one day after conditioning, but rats retain a considerable amount of contextual fear when hippocampectomy is delayed by four weeks. In mice, examined at 4 weeks after conditioning, the hippocampus methylations and demethylations were reversed (the hippocampus is needed to form memories but memories are not stored there) while substantial differential CpG methylation and demethylation occurred in cortical neurons during memory maintenance. There were 1,223 differentially methylated genes in the anterior cingulate cortex (see Figure) of mice four weeks after contextual fear conditioning. Thus, while there were many methylations in the hippocampus shortly after memory was formed, all these hippocampus methylations were demethylated as soon as four weeks later.
Li et al. reported one example of the relationship between expression of a TET protein, demethylation and memory while using extinction training. Extinction training is the disappearance of a previously learned behavior when the behavior is not reinforced.
A comparison between infralimbic prefrontal cortex (ILPFC) neuron samples derived from mice trained to fear an auditory cue and extinction-trained mice revealed dramatic experience-dependent genome-wide differences in the accumulation of 5-hmC in the ILPFC in response to learning. Extinction training led to a significant increase in TET3 messenger RNA levels within cortical neurons. TET3 was selectively activated within the adult neo-cortex in an experience-dependent manner.
A short hairpin RNA (shRNA) is an artificial RNA molecule with a tight hairpin turn that can be used to silence target gene expression via RNA interference. Mice trained in the presence of TET3-targeted shRNA showed a significant impairment in fear extinction memory. | 1 | Gene expression + Signal Transduction |
A lixiviant is a chemical used in hydrometallurgy to extract elements from its ore. One of the most famous lixiviants is cyanide, which is used in extracting 90% of mined gold. The combination of cyanide and air converts gold particles into a soluble salt. Once separated from the bulk gangue, the solution is processed in a series of steps to give the metal. | 0 | Metallurgy |
A promoter is defined in RegulonDB as the nucleotide sequence 60 bases upstream and 20 downstream from the precise initiation of transcription or +1. Terminators are regions where transcription ends, and RNA Polymerase unbinds from DNA. | 1 | Gene expression + Signal Transduction |
Development of AFA superalloys with a 35 wt.% Ni-base have shown potential for use in operating temperatures upwards to 1,100 °C. | 0 | Metallurgy |
The first reverberatory furnaces were perhaps in the medieval period, and were used for melting bronze for casting bells. They were first applied to smelting metals in the late 17th century. Sir Clement Clerke and his son Talbot built cupolas or reverberatory furnaces in the Avon Gorge below Bristol in about 1678. In 1687, while obstructed from smelting lead (by litigation), they moved on to copper. In the following decades, reverberatory furnaces were widely adopted for smelting these metals and also tin. They had the advantage over older methods that the fuel was mineral coal, not charcoal or white coal (chopped dried wood).
In the 1690s, they (or associates) applied the reverberatory furnace (in this case known as an air furnace) to melting pig iron for foundry purposes. This was used at Coalbrookdale and various other places, but became obsolete at the end of the 18th century with the introduction of the foundry cupola furnace, which was a kind of small blast furnace, and a quite different species from the reverberatory furnace.
The puddling furnace, introduced by Henry Cort in the 1780s to replace the older finery process, was also a variety of reverberatory furnace. | 0 | Metallurgy |
PA is a vital cell lipid that acts as a biosynthetic precursor for the formation (directly or indirectly) of all acylglycerol lipids in the cell.
In mammalian and yeast cells, two different pathways are known for the de novo synthesis of PA, the glycerol 3-phosphate pathway or the dihydroxyacetone phosphate pathway. In bacteria, only the former pathway is present, and mutations that block this pathway are lethal, demonstrating the importance of PA. In mammalian and yeast cells, where the enzymes in these pathways are redundant, mutation of any one enzyme is not lethal. However, it is worth noting that in vitro, the various acyltransferases exhibit different substrate specificities with respect to the acyl-CoAs that are incorporated into PA. Different acyltransferases also have different intracellular distributions, such as the endoplasmic reticulum (ER), the mitochondria or peroxisomes, and local concentrations of activated fatty acids. This suggests that the various acyltransferases present in mammalian and yeast cells may be responsible for producing different pools of PA.
The conversion of PA into diacylglycerol (DAG) by LPPs is the commitment step for the production of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS). In addition, DAG is also converted into CDP-DAG, which is a precursor for phosphatidylglycerol (PG), phosphatidylinositol (PI) and phosphoinositides (PIP, PIP, PIP).
PA concentrations are maintained at extremely low levels in the cell by the activity of potent LPPs. These convert PA into DAG very rapidly and, because DAG is the precursor for so many other lipids, it too is soon metabolised into other membrane lipids. This means that any upregulation in PA production can be matched, over time, with a corresponding upregulation in LPPs and in DAG metabolising enzymes.
PA is, therefore, essential for lipid synthesis and cell survival, yet, under normal conditions, is maintained at very low levels in the cell. | 1 | Gene expression + Signal Transduction |
The carbothermic route to magnesium has been recognized as a low energy, yet high productivity path to magnesium extraction. The chemistry is as follow:
The reaction between magnesia and carbon produces a magnesium and carbon monoxide vapour. A disadvantage of this method is that slow cooling the vapour can cause the reaction to quickly revert back. To prevent this from happening, the magnesium can be dissolved directly in a suitable metal solvent before reversion starts happening. Rapid quenching of the vapour can also be performed to prevent reversion.
The Bolzano process is very similar to the Pidgeon process. The difference between the Pidgeon process and the Bolzano process is that the heating process is done through electric heating conductors, and retorts are placed vertically into large blocks in the Bolzano process. A complete reaction takes about 20–24 hours. The Pidgeon method is less technologically complex and because of distillation/vapour deposition conditions, a high purity product is easily achievable.
Besides the Pigeon process, the second most used process for magnesium production is electrolysis. This is a two step process. The first step is to prepare feedstock containing magnesium chloride and the second step is to dissociate the compound in electrolytic cells as magnesium metal and chlorine gas. The basic reaction is as follows:
The magnesium chloride can be obtained using the Dow process, a process that mixes sea water and dolomite in a flocculator or by dehydration of magnesium chloride brines. The electrolytic cells are partially submerged in a molten salt electrolyte to which the produced magnesium chloride is added in concentrations between 6-18%. The temperatures at which this reaction is operated is between 680 and 750 degrees Celsius. This process does have its fair share of disadvantages including production of harmful chlorine gas and the overall reaction being very energy intensive, creating environmental risks. The Pidgeon process is more advantageous regarding its simplicity, shorter construction period, low power consumption and overall good magnesium quality compared to the electrolysis method. | 0 | Metallurgy |
Lead can form a low-melting slag capable of fluxing protective oxide scales. Lead is more often known for causing stress corrosion cracking in common materials that are exposed to molten lead. The cracking tendency of lead has been known for some time, since most iron based alloys, including those used in steel containers and vessels for molten lead baths, usually fail due to cracking. | 0 | Metallurgy |
Cast bronzes are known to have been produced in Africa by the 9th century AD in Igboland (Igbo-Ukwu) in Nigeria, the 12th century AD in Yorubaland (Ife) and the 15th century AD in the kingdom of Benin. Some portrait heads remain.
Benin mastered bronze during the 16th century, produced portraiture and reliefs in the metal using the lost wax process. | 0 | Metallurgy |
Chromatin assembly factor-1 (CAF-1) is a protein complex — including Chaf1a (p150), Chaf1b (p60), and p48 subunits in humans, or Cac1, Cac2, and Cac3, respectively, in yeast— that assembles histone tetramers onto replicating DNA during the S phase of the cell cycle. | 1 | Gene expression + Signal Transduction |
TRIM28 has been shown to interact with:
* CBX5,
* CEBPB,
* Glucocorticoid receptor,
* SETDB1 and
* ZNF10. | 1 | Gene expression + Signal Transduction |
The Society for Mining, Metallurgy & Exploration publishes the monthly magazine Mining Engineering since 1949. | 0 | Metallurgy |
A piece of alloy metal containing a precious metal may also have the weight of its precious component referred to as its "fine weight". For example, 1 troy ounce of 18 karat gold (which is 75% gold) may be said to have a fine weight of 0.75 troy ounces.
Most modern government-issued bullion coins specify their fine weight. For example, the American Gold Eagle is embossed One Oz. Fine Gold and weighs 1.091 troy oz. | 0 | Metallurgy |
The ability of enhancers to activate imprinted genes is dependent on the presence of an insulator on the unmethylated allele between the two genes. An example of this is the Igf2-H19 imprinted locus. In this locus the CTCF protein regulates imprinted expression by binding to the unmethylated maternal imprinted control region (ICR) but not on the paternal ICR. When bound to the unmethylated maternal sequence, CTCF effectively blocks downstream enhancer elements from interacting with the Igf2 gene promoter, leaving only the H19 gene to be expressed. | 1 | Gene expression + Signal Transduction |
Traditionally, enhancers were identified by enhancer trap techniques using a reporter gene or by comparative sequence analysis and computational genomics. In genetically tractable models such as the fruit fly Drosophila melanogaster, for example, a reporter construct such as the lacZ gene can be randomly integrated into the genome using a P element transposon. If the reporter gene integrates near an enhancer, its expression will reflect the expression pattern driven by that enhancer. Thus, staining the flies for LacZ expression or activity and cloning the sequence surrounding the integration site allows the identification of the enhancer sequence.
The development of genomic and epigenomic technologies, however, has dramatically changed the outlook for cis-regulatory modules (CRM) discovery. Next-generation sequencing (NGS) methods now enable high-throughput functional CRM discovery assays, and the vastly increasing amounts of available data, including large-scale libraries of transcription factor-binding site (TFBS) motifs, collections of annotated, validated CRMs, and extensive epigenetic data across many cell types, are making accurate computational CRM discovery an attainable goal. An example of NGS-based approach called DNase-seq have enabled identification of nucleosome-depleted, or open chromatin regions, which can contain CRM. More recently techniques such as ATAC-seq have been developed which require less starting material. Nucelosome depleted regions can be identified in vivo through expression of Dam methylase, allowing for greater control of cell-type specific enhancer identification.
Computational methods include comparative genomics, clustering of known or predicted TF-binding sites, and supervised machine-learning approaches trained on known CRMs.
All of these methods have proven effective for CRM discovery, but each has its own considerations and limitations, and each is subject to a greater or lesser number of false-positive identifications.
In the comparative genomics approach, sequence conservation of non-coding regions can be indicative of enhancers. Sequences from multiple species are aligned, and conserved regions are identified computationally. Identified sequences can then be attached to a reporter gene such as green fluorescent protein or lacZ to determine the in vivo pattern of gene expression produced by the enhancer when injected into an embryo. mRNA expression of the reporter can be visualized by in situ hybridization, which provides a more direct measure of enhancer activity, since it is not subjected to the complexities of translation and protein folding. Although much evidence has pointed to sequence conservation for critical developmental enhancers, other work has shown that the function of enhancers can be conserved with little or no primary sequence conservation. For example, the RET enhancers in humans have very little sequence conservation to those in zebrafish, yet both species' sequences produce nearly identical patterns of reporter gene expression in zebrafish. Similarly, in highly diverged insects (separated by around 350 million years), similar gene expression patterns of several key genes was found to be regulated through similarly constituted CRMs although these CRMs do not show any appreciable sequence conservation detectable by standard sequence alignment methods such as BLAST. | 1 | Gene expression + Signal Transduction |
Besides de novo synthesis, PA can be formed in three ways:
* By phospholipase D (PLD), via the hydrolysis of the P-O bond of phosphatidylcholine (PC) to produce PA and choline.
* By the phosphorylation of diacylglycerol (DAG) by DAG kinase (DAGK).
* By the acylation of lysophosphatidic acid by lysoPA-acyltransferase (LPAAT); this is the most common pathway.
The glycerol 3-phosphate pathway for de novo synthesis of PA is shown here:
In addition, PA can be converted into DAG by lipid phosphate phosphohydrolases (LPPs) or into lyso-PA by phospholipase A (PLA). | 1 | Gene expression + Signal Transduction |
Design errors arise when the desired use case was not properly accounted for, leading to a ineffective design, such as the stress state in service or potential corrosive agents in the service environment. Design errors often include dimensioning and materials selection, but it can also be the complete design. | 0 | Metallurgy |
LHCGR have been found in many types of extragonadal tissues, and the physiologic role of some has remained largely unexplored. Thus receptors have been found in the uterus, sperm, seminal vesicles, prostate, skin, breast, adrenals, thyroid, neural retina, neuroendocrine cells, and (rat) brain. | 1 | Gene expression + Signal Transduction |
IP's main functions are to mobilize Ca from storage organelles and to regulate cell proliferation and other cellular reactions that require free calcium. In smooth muscle cells, for example, an increase in concentration of cytoplasmic Ca results in the contraction of the muscle cell.
In the nervous system, IP serves as a second messenger, with the cerebellum containing the highest concentration of IP receptors. There is evidence that IP receptors play an important role in the induction of plasticity in cerebellar Purkinje cells. | 1 | Gene expression + Signal Transduction |
The first swords known so far date to ca. the 33rd to 31st centuries BCE, during the Early Bronze Age, and have been founds at Arslantepe by Marcella Frangipane of Sapienza University of Rome. A cache of nine swords and daggers was found; they are cast from an arsenic–copper alloy. Analysis of two swords showed a copper/arsenic composition of 96%/3.15% and 93%/2.65%. Two daggers tested at copper/arsenic 96%/3.99% and 97%/3.06% with a third at copper/silver composition of 50%/35% with a trace of arsenic. Among them, three swords were beautifully inlaid with silver. These objects were found in the "hall of weapons" in the area of the palace.
These weapons have a total length of 45 to 60 cm which suggests their description as either short swords or long daggers.
These discoveries were made back in the 1980s. They belong to the local phase VI A. Also, 12 spearheads were found. These objects were dated to the period VI A (3400-3200 BC). Phase VI A at Arslantepe ended in destruction—the city was burned.
Kfar Monash Hoard was found in 1962 in Israel. Among the many copper objects in it, "Egyptian type" copper axes were found. These axes were made using copper-arsenic-nickel (CuAsNi) alloy that probably originated in Arslantepe area. Objects from Arslantepe using such polymetallic ores are mainly ascribed to Level VIA (3400–3000 BCE), dating to the Uruk period.
The next Phases or periods were VI B1 and VI B2. This is the time to which the other big discovery at Arslantepe belongs. This is the rich “Royal Tomb” where high quality pottery, and a large number of refined metal objects, made with several kinds of copper based alloys, were found. A sword was also found in the tomb. This tomb is also known as the tomb of "Signor Arslantepe", as he was called by archaeologists. He was about 40 years old, and the tomb is radiocarbon dated to 3085–2900 Cal. BC.
This “Royal Tomb” dates to the beginning of period VI B2, or perhaps even earlier to period VI B1. There’s a considerable similarity between these two groups of objects in the “hall of weapons”, and in the “Royal Tomb”, and the times of manufacture of some of them must have been pretty close together. | 0 | Metallurgy |
The plant sorghum is well established model organism and can adapt in hot and dry environments. For this reason, it is used as a model to study calmodulins role in plants. Sorghum contains seedlings that express a glycine-rich RNA-binding protein, SbGRBP. This particular protein can be modulated by using heat as a stressor. Its unique location in the cell nucleus and cytosol demonstrates interaction with calmodulin that requires the use of Ca. By exposing the plant to versatile stress conditions, it can cause different proteins that enable the plant cells to tolerate environmental changes to become repressed. These modulated stress proteins are shown to interact with CaM. The CaMBP' genes expressed in the sorghum are depicted as a “model crop” for researching the tolerance to heat and drought stress. | 1 | Gene expression + Signal Transduction |
Plaster casting is similar to sand casting except that plaster of paris is used instead of sand as a mold material. Generally, the form takes less than a week to prepare, after which a production rate of 1–10 units/hr-mold is achieved, with items as massive as and as small as with very good surface finish and close tolerances. Plaster casting is an inexpensive alternative to other molding processes for complex parts due to the low cost of the plaster and its ability to produce near net shape castings. The biggest disadvantage is that it can only be used with low melting point non-ferrous materials, such as aluminium, copper, magnesium, and zinc. | 0 | Metallurgy |
Non-protein phosphorylation has three general forms
* As a regulatory mechanism to control the function of the substrate, similar to the role of protein phosphorylation. Phosphoinositide lipids are important signaling molecules that have a variety of dedicated kinases and phosphatases.
* As an energetic intermediate. The phosphate bond is high-energy, so adding a phosphate increases the energy of a molecule, and removal of the phosphate can provide energy for an otherwise unfavorable reaction. For instance Glucose 6-phosphatase removes a phosphate group from glucose to complete gluconeogenesis.
* In biosynthesis, where the phosphate is a functional part of the mature molecule, and dephosphorylation degrades it or changes function. Nucleotidases are phosphatases used in nucleotide biosynthesis and breakdown.
The human non-protein phosphatome has been cataloged, but most phosphatome analyses are restricted to protein and lipid phosphatases that have regulatory functions. | 1 | Gene expression + Signal Transduction |
Mammalian cell expression systems are essential for the transient production of recombinant proteins and their complementary post-translational modifications. In fact, approximately half of the current commercially available therapeutic proteins are produced in mammalian cells. However, mammalian cell systems' slow growth, precise growth requirements, and potential risk of infection by animal viruses present a number of challenges. As a result, a growing number of mammalian cell lines have been established to serve as hosts for transient recombinant protein production. | 1 | Gene expression + Signal Transduction |
The restoration of the plant began immediately after the end of the battles for the city, and on February 14, 1944, the plant carried out the first steel smelting from the flat furnace; in March 1944, the rolling mill and the first blast furnace were put into operation; between 1944 and 1946, the enterprise was awarded the Red flag ten times by the Soviet Defense Committee for the successful restoration of the facility.
In 1950, the plant returned to prewar levels of steel production and rolled metal production.
In 1952, the plant was the first in the world to implement a steam evaporation system for cooling flat furnace elements, the development and implementation of which earned two employees of the plant the Stalin Prize.
The plant also specialized in the production of strip valve profiles and spring strips for Pobeda cars in the Fourth Five-Year Plan.
In 1955, the Museum of the History of the DMZ (DMP) was opened.
In 1960, a four-jet continuous casting machine for steel blanks was put into operation at the plant. Also, in 1960, the plant, among the first enterprises of the USSR, mastered the smelting of iron on natural gas (for this achievement, the director of the plant I. M. Ektov and the head of the blast furnace shop of the plant G. A. Panev were awarded the Lenin Prize in 1960).
February 7, 1966 the plant was awarded the Order of Lenin.
In 1967, the plant received a new name: “named after V. I. Lenin.”
In 1970, the plant produced 5.9 times more iron, 5.3 times more steel, and produced 5.5 times more rolled metal than in 1913. Also, in 1970, the Living Memorial was built - immortal, in honor of the workers of the DMZ who died in the Great Patriotic War.
In 1972, the plant was awarded the Order of the October Revolution.
In 1974, a swaging mill 950/900 was built at the plant.
From the early 1980s, DMZ'smain products were rolled bars and rolled sheets of cast iron, steel, high-grade and alloy steel.
By early 1986, the plant was one of the largest industrial enterprises in Donetsk, whose main products were steel, cast iron, sheet metal and long products. | 0 | Metallurgy |
White etching cracks (WEC), or white structure flaking or brittle flaking, is a type of rolling contact fatigue (RCF) damage that can occur in bearing steels under certain conditions, such as hydrogen embrittlement, high stress, inadequate lubrication, and high temperature. WEC is characterised by the presence of white areas of microstructural alteration in the material, which can lead to the formation of small cracks that can grow and propagate over time, eventually leading to premature failure of the bearing. WEC has been observed in a variety of applications, including wind turbine gearboxes, automotive engines, and other heavy machinery. The exact mechanism of WEC formation is still a subject of research, but it is believed to be related to a combination of microstructural changes, such as phase transformations and grain boundary degradation, and cyclic loading. | 0 | Metallurgy |
Wet storage stain is a white, crumbly, and porous substance that is a mixture of three chemical compounds: 2ZnCO·3Zn(OH), ZnO, and β-Zn(OH). Underneath the white coating is usually a dark gray surface. The corrosion product is very voluminous; it is approximately 100 times greater in volume than the zinc consumed. Because of this the corrosion is not usually detrimental to the usability of the item, unless the zinc surface is only a thin coating, such as zinc electroplating.
Wet storage stain only occurs in situations where there is a lack of oxygen or carbon dioxide, because it usually forms zinc oxide and zinc hydroxide in open air environments. These oxides are usually present on zinc surfaces, but do not protect them from wet storage stain because they are only loosely adherent to the surface and any moisture can attack the oxides from underneath. Also, chlorides and sulfates accelerate the formation of corrosion. | 0 | Metallurgy |
Interleukin 34 (IL-34) is a protein belonging to a group of cytokines called interleukins. It was originally identified in humans, by large scale screening of secreted proteins; chimpanzee, murine, rat and chicken interleukin 34 orthologs have also been found. The protein is composed of 241 amino acids, 39 kilodaltons in mass, and forms homodimers. IL-34 increases growth or survival of immune cells known as monocytes; it elicits its activity by binding the Colony stimulating factor 1 receptor.
Messenger RNA (mRNA) expression of human IL-34 is most abundant in spleen but occurs in several other tissues: thymus, liver, small intestine, colon, prostate gland, lung, heart, brain, kidney, testes, and ovary. The discovery of IL-34 protein in the red pulp of the spleen suggests involvement in growth and development of myeloid cells, consistent with its activity on monocytes. | 1 | Gene expression + Signal Transduction |
In iron ore smelting, haematite gets reduced at the top of the furnace, where temperature is in the range 600 – 700 °C. The Ellingham diagram indicates that in this range carbon monoxide acts as a stronger reducing agent than carbon since the process
:2 CO + → 2
has a more-negative free energy change than the process:
:2 C + → 2 CO.
In the upper part of the blast furnace, haematite is reduced by CO (produced by oxidation of coke lower down at the bottom of blast furnace, at higher temperature) even in the presence of carbon – though this is mainly because the kinetics for gaseous CO reacting with the ore are better. | 0 | Metallurgy |
Social insect colonies are an excellent example of a decentralized system, because no individual is in charge of directing or making decisions for the colony. Several groups of social insects have been shown to use quorum sensing in a process that resembles collective decision-making. | 1 | Gene expression + Signal Transduction |
These adenylyl cyclases are the most familiar based on extensive study due to their important roles in human health. They are also found in some bacteria, notably Mycobacterium tuberculosis where they appear to have a key role in pathogenesis. Most AC-III's are integral membrane proteins involved in transducing extracellular signals into intracellular responses. A Nobel Prize was awarded to Earl Sutherland in 1971 for discovering the key role of AC-III in human liver, where adrenaline indirectly stimulates AC to mobilize stored energy in the "fight or flight" response. The effect of adrenaline is via a G protein signaling cascade, which transmits chemical signals from outside the cell across the membrane to the inside of the cell (cytoplasm). The outside signal (in this case, adrenaline) binds to a receptor, which transmits a signal to the G protein, which transmits a signal to adenylyl cyclase, which transmits a signal by converting adenosine triphosphate to cyclic adenosine monophosphate (cAMP). cAMP is known as a second messenger.
Cyclic AMP is an important molecule in eukaryotic signal transduction, a so-called second messenger. Adenylyl cyclases are often activated or inhibited by G proteins, which are coupled to membrane receptors and thus can respond to hormonal or other stimuli. Following activation of adenylyl cyclase, the resulting cAMP acts as a second messenger by interacting with and regulating other proteins such as protein kinase A and cyclic nucleotide-gated ion channels.
Photoactivated adenylyl cyclase (PAC) was discovered in Euglena gracilis and can be expressed in other organisms through genetic manipulation. Shining blue light on a cell containing PAC activates it and abruptly increases the rate of conversion of ATP to cAMP. This is a useful technique for researchers in neuroscience because it allows them to quickly increase the intracellular cAMP levels in particular neurons, and to study the effect of that increase in neural activity on the behavior of the organism. A green-light activated rhodopsin adenylyl cyclase (CaRhAC) has recently been engineered by modifying the nucleotide binding pocket of rhodopsin guanylyl cyclase. | 1 | Gene expression + Signal Transduction |
Ores mined for their base metal content often contain precious metals, usually gold and silver. These have to be removed from the base metals as part of the refining processes used to purify the metals. In the case of copper electrolytic refining, the gold and silver fall to the bottom of the electrolytic refining cell as “slimes” that are subsequently treated to recover gold and silver as byproducts. In the case of lead refining, silver, gold, and other precious metals are typically removed using the Parkes process, in which zinc is added to the impure lead bullion to collect the silver, gold and other precious metals.
The BRM lead refinery at Northfleet in England uses the Parkes process followed by liquation and a vacuum induction retort to recover precious metals. The product of this process is a feed for the BBOC consisting of a mixture of lead, silver (60–75%), zinc (2–3%) and copper (2–3%), with trace amounts of gold. Prior to the development of the BBOC, BRM used cupellation in a 15 tonne (“t”) reverberatory cupellation furnace to recover the precious metals from this mixture. Three of these furnaces were used to produce 450 t of silver per year.
Cupellation works by exposing the mixture at high temperature to air or oxygen. The base metals, being less noble than silver and gold, react with the oxygen to form their oxides, which separate from the noble metals to form a slag that floats on the top of the residual metals (or “doré”). At BRM, the doré contains 99.7% silver.
To maximize the oxygen transfer from the blast air in the reverberatory furnace, a shallow bath is used, thus increasing the surface-area-to-volume ratio of the furnace.
A problem with using reverberatory furnaces for cupellation is that the zinc oxidizes first, forming a crust across the top of the molten material. This crust prevents the penetration of oxygen to the rest of the material, and so it has to be manually broken up and removed using a rabble bar. This is both labor-intensive and also results in the loss of some of the silver. Similarly, the oxidized lead slag has to be removed when it forms to maintain the operation, and its removal also results in loss of silver.
The BBOC was developed by BRM personnel as a way of reducing these and other problems, such as low energy efficiency and low oxygen utilization, associated with the reverberatory cupellation process. | 0 | Metallurgy |
An mRNA molecule is said to be monocistronic when it contains the genetic information to translate only a single protein chain (polypeptide). This is the case for most of the eukaryotic mRNAs. On the other hand, polycistronic mRNA carries several open reading frames (ORFs), each of which is translated into a polypeptide. These polypeptides usually have a related function (they often are the subunits composing a final complex protein) and their coding sequence is grouped and regulated together in a regulatory region, containing a promoter and an operator. Most of the mRNA found in bacteria and archaea is polycistronic, as is the human mitochondrial genome. Dicistronic or bicistronic mRNA encodes only two proteins. | 1 | Gene expression + Signal Transduction |
Histone modification is a well-studied mechanism to transiently adjust chromatin density. Pioneer factors can play a role in this by binding specific enhancers and flagging histone modification enzymes to that specific gene. Repressive pioneer factors can inhibit transcription by recruiting factors that modify histones that further tighten the chromatin. This is important to limit gene expression to specific cell types and has to be removed only when cell differentiation begins. FoxD3 has been associated as a repressor of both B-cell and melanocytic cell differentiation pathways, maintaining repressive histone modifications where bound, that have to be overcome to start differentiation. Pioneer factors can also be associated with recruiting transcription-activating histone modifications. Enzymes that modify H3K4 with mono and di-methylation are associated with increasing transcription and have been shown to bind pioneer factors. In B cell differentiation PU.1 is necessary to signal specific histones for activating H3K4me1 modifications that differentiate hematopoietic stem cells into either the B-cell or macrophage lineage. FoxA1 binding induces HSK4me2 during neuronal differentiation of pluripotent stem cells as well as the loss of DNA methylation. SOX9 recruits histone modification enzymes MLL3 and MLL4 to deposit H3K4me1 prior to the opening of enhancers in developing hair follicle and basal cell carcinoma. | 1 | Gene expression + Signal Transduction |
Monoamines transported by VMATs are mainly noradrenaline, adrenaline, dopamine, serotonin, histamine, and trace amines. Exogenous substrates include guanethidine and MPP. | 1 | Gene expression + Signal Transduction |
Aluminothermic reactions are exothermic chemical reactions using aluminium as the reducing agent at high temperature. The process is industrially useful for production of alloys of iron. The most prominent example is the thermite reaction between iron oxides and aluminium to produce iron itself:
: FeO + 2 Al → 2 Fe + AlO
This specific reaction is however not relevant to the most important application of aluminothermic reactions, the production of ferroalloys. For the production of iron, a cheaper reducing agent, coke, is used instead via the carbothermic reaction. | 0 | Metallurgy |
The experimental microorganism used by François Jacob and Jacques Monod was the common laboratory bacterium, E. coli, but many of the basic regulatory concepts that were discovered by Jacob and Monod are fundamental to cellular regulation in all organisms. The key idea is that proteins are not synthesized when they are not needed—E. coli conserves cellular resources and energy by not making the three Lac proteins when there is no need to metabolize lactose, such as when other sugars like glucose are available. The following section discusses how E. coli controls certain genes in response to metabolic needs.
During World War II, Monod was testing the effects of combinations of sugars as nutrient sources for E. coli and B. subtilis. Monod was following up on similar studies that had been conducted by other scientists with bacteria and yeast. He found that bacteria grown with two different sugars often displayed two phases of growth. For example, if glucose and lactose were both provided, glucose was metabolized first (growth phase I, see Figure 2) and then lactose (growth phase II). Lactose was not metabolized during the first part of the diauxic growth curve because β-galactosidase was not made when both glucose and lactose were present in the medium. Monod named this phenomenon diauxie.
Monod then focused his attention on the induction of β-galactosidase formation that occurred when lactose was the sole sugar in the culture medium. | 1 | Gene expression + Signal Transduction |
Cataclasis, or comminution, is a non-elastic brittle mechanism that operates under low to moderate homologous temperatures, low confining pressure and relatively high strain rates. It occurs only above a certain differential stress level, which is dependent on fluid pressure and temperature. Cataclasis accommodates the fracture and crushing of grains, causing grain size reduction, along with frictional sliding on grain boundaries and rigid body grain rotation. Intense cataclasis occurs in thin zones along slip or fault surfaces where extreme grain size reduction occurs. In rocks, cataclasis forms a cohesive and fine-grained fault rock called cataclasite. Cataclastic flow occurs during shearing when a rock deform by microfracturing and frictional sliding where tiny fractures (microcracks), and associated rock fragments move past each other. Cataclastic flow usually occurs at diagenetic to low-grade metamorphic conditions. However, this depends on the mineralogy of the material and the extent of pore fluid pressure. Cataclastic flow is generally unstable and will terminate by the localization of deformation into slip on fault planes. | 0 | Metallurgy |
Pouring metal defects include misruns, cold shuts, and inclusions. A misrun occurs when the liquid metal does not completely fill the mould cavity, leaving an unfilled portion. Cold shuts occur when two fronts of liquid metal do not fuse properly in the mould cavity, leaving a weak spot. Both are caused by either a lack of fluidity in the molten metal or cross-sections that are too narrow. The fluidity can be increased by changing the chemical composition of the metal or by increasing the pouring temperature. Another possible cause is back pressure from improperly vented mould cavities.
Misruns and cold shuts are closely related and both involve the material freezing before it completely fills the mould cavity. These types of defects are serious because the area surrounding the defect is significantly weaker than intended. The castability and viscosity of the material can be important factors with these problems. Fluidity affects the minimum section thickness that can be cast, the maximum length of thin sections, fineness of feasibly cast details, and the accuracy of filling mould extremities. There are various ways of measuring the fluidity of a material, although it usually involves using a standard mould shape and measuring the distance the material flows. Fluidity is affected by the composition of the material, freezing temperature or range, surface tension of oxide films, and, most importantly, the pouring temperature. The higher the pouring temperature, the greater the fluidity; however, excessive temperatures can be detrimental, leading to a reaction between the material and the mould; in casting processes that use a porous mould material the material may even penetrate the mould material.
The point at which the material cannot flow is called the coherency point. The point is difficult to predict in mould design because it is dependent on the solid fraction, the structure of the solidified particles, and the local shear strain rate of the fluid. Usually this value ranges from 0.4 to 0.8.
An inclusion is a metal contamination of dross, if solid, or slag, if liquid. These usually are impurities in the pour metal (generally oxides, less frequently nitrides, carbides, or sulfides), material that is eroded from furnace or ladle linings, or contaminates from the mould. In the specific case of aluminium alloys, it is important to control the concentration of inclusions by measuring them in the liquid aluminium and taking actions to keep them to the required level.
There are a number of ways to reduce the concentration of inclusions. In order to reduce oxide formation the metal can be melted with a flux, in a vacuum, or in an inert atmosphere. Other ingredients can be added to the mixture to cause the dross to float to the top where it can be skimmed off before the metal is poured into the mould. If this is not practical, then a special ladle that pours the metal from the bottom can be used. Another option is to install ceramic filters into the gating system. Otherwise swirl gates can be formed which swirl the liquid metal as it is poured in, forcing the lighter inclusions to the center and keeping them out of the casting. If some of the dross or slag is folded into the molten metal then it becomes an entrainment defect. | 0 | Metallurgy |
Targets of (p)ppGpp include rRNA operons, of which there are seven in E.coli, all of which have 2 promoters. When (p)ppGpp associates with the promoter it affects the RNA polymerase enzyme's ability to bind and initiate transcription. It is thought that (p)ppGpp may affect the stability of the open complex formed by RNA polymerase on DNA and therefore affect promoter clearance. Its presence also leads to an increase in pausing during transcription elongation and it competes with nucleoside triphosphate substrates.
There is now a consensus that (p)ppGpp is a determinant of growth rate control rather than nucleoside triphosphate (NTP) substrate concentrations. | 1 | Gene expression + Signal Transduction |
Fifty-six new copper discoveries have been made during the three decades 1975–2005. World discoveries of new copper deposits are said to have peaked in 1996. However, according to the US Geological Survey (USGS), remaining world copper reserves have more than doubled since then, from 310 million metric tons in 1996 to 890 million metric tons in 2022. | 0 | Metallurgy |
The ore is comminuted using grinding machinery. Depending on the ore, it is sometimes further concentrated by froth flotation or by centrifugal (gravity) concentration. Water is added to produce a slurry or pulp. The basic ore slurry can be combined with a solution of sodium cyanide or potassium cyanide; many operations use calcium cyanide, which is more cost effective.
To prevent the creation of toxic hydrogen cyanide during processing, slaked lime (calcium hydroxide) or soda (sodium hydroxide) is added to the extracting solution to ensure that the acidity during cyanidation is maintained over pH 10.5 - strongly basic.
Lead nitrate can improve gold leaching speed and quantity recovered, particularly in processing partially oxidized ores. | 0 | Metallurgy |
In metallurgy, refining consists of purifying an impure metal. It is to be distinguished from other processes such as smelting and calcining in that those two involve a chemical change to the raw material, whereas in refining, the final material is usually identical chemically to the original one, only it is purer. The processes used are of many types, including pyrometallurgical and hydrometallurgical techniques. | 0 | Metallurgy |
The access fittings - such as flanged, flare-weld, etc.- are used for connection and access to coupons and probes. The general size of A/F is 2" which is called 2" system. But for small pipe sizes, 1" system can be used. | 0 | Metallurgy |
Plastic pipes under water or other fluids experience hydrodynamic forces that can result in fatigue. The pipes reach failure sooner as temperatures and exposure to aggressive substances increase. For static fatigue tests, rotating machines apply weight on the material under study causing it to bend in different directions, which weakens the material overtime. | 0 | Metallurgy |
EpoRs role in lineage commitment is currently unclear. EpoR expression can extend as far back as the hematopoietic stem cell compartment. It is unknown whether EpoR signaling plays a permissive (i.e. induces only survival) or an instructive (i.e. upregulates erythroid markers to lock progenitors to a predetermined differentiation path) role in early, multipotent progenitors in order to produce sufficient erythroblast numbers. Current publications in the field suggest that it is primarily permissive. The generation of BFU-e and CFU-e progenitors was shown to be normal in rodent embryos knocked out for either Epo or EpoR. An argument against such lack of requirement is that in response to Epo or hypoxic stress, the number of early erythroid stages, the BFU-e and CFU-e, increases dramatically. However, it is unclear if it is an instructive signal or, again, a permissive signal. One additional point is that signaling pathways activated by the EpoR are common to many other receptors; replacing EpoR with prolactin receptor supports erythroid survival and differentiation in vitro. Together, these data suggest that commitment to erythroid lineage likely does not happen due to EpoRs as-yet-unknown instructive function, but possibly due to its role in survival at the multipotent progenitor stages. | 1 | Gene expression + Signal Transduction |
Enhancers as sites of extragenic transcription were initially discovered in genome-wide studies that identified enhancers as common regions of RNA polymerase II (RNA pol II) binding and non-coding RNA transcription. The level of RNA pol II–enhancer interaction and RNA transcript formation were found to be highly variable among these initial studies. Using explicit chromatin signature peaks, a significant proportion (~70%) of extragenic RNA Pol II transcription start sites were found to overlap enhancer sites in murine macrophages. Out of 12,000 neuronal enhancers in the mouse genome, almost 25% of the sites were found to bind RNA Pol II and generate transcripts. In parallel studies, 4,588 high confidence extragenic RNA Pol II binding sites were identified in murine macrophages stimulated with the inflammatory mediater lipopolysaccharide to induce transcription. These eRNAs, unlike messenger RNAs (mRNAs), lacked modification by polyadenylation, were generally short and non-coding, and were bidirectionally transcribed. Later studies revealed the transcription of another type of eRNAs, generated through unidirectional transcription, that were longer and contained a poly A tail. Furthermore, eRNA levels were correlated with mRNA levels of nearby genes, suggesting the potential regulatory and functional role of these non-coding enhancer RNA molecules. | 1 | Gene expression + Signal Transduction |
The Open Regulatory Annotation Database (also known as ORegAnno) is designed to promote community-based curation of regulatory information. Specifically, the database contains information about regulatory regions, transcription factor binding sites, regulatory variants, and haplotypes. | 1 | Gene expression + Signal Transduction |
Gas Engine Row has many large stationary gas engines from the early 1900s. On the row is an operational Fairbanks-Morse mine hoist winding engine, a pumphouse powered by a Fairbanks-Morse engine, a horsepower 1922 Fairbanks-Morse type YV engine connected to a large alternator, an enormous 1914 Chicago-Pneumatic hot-bulb air compressor, an Western engine, a Western engine, a Western engine and many other stationary engines. Almost all of the engines on Gas Engine Row can be seen running during the shows.
Steam Engine Row showcases many different types and sizes of stationary steam engines; from a monstrous Allis Chalmers Corliss engine with a flywheel, to a small J. Lefel & Sons portable engine. They are all powered by steam from two large boilers, nicknamed Pat and Rich, after two long-time museum volunteers who maintain and operate them. | 0 | Metallurgy |
The advantages are:
*Decrease in yield strength, therefore it is easier to work and uses less energy or force
*Increase in ductility
*Elevated temperatures increase diffusion which can remove or reduce chemical inhomogeneities
*Pores may reduce in size or close completely during deformation
*In steel, the weak, ductile, face-centered-cubic austenite microstructure is deformed instead of the strong body-centered-cubic ferrite microstructure found at lower temperatures
Usually the initial workpiece that is hot worked was originally cast. The microstructure of cast items does not optimize the engineering properties, from a microstructure standpoint. Hot working improves the engineering properties of the workpiece because it replaces the microstructure with one that has fine spherical shaped grains. These grains increase the strength, ductility, and toughness of the material.
The engineering properties can also be improved by reorienting the inclusions (impurities). In the cast state the inclusions are randomly oriented, which, when intersecting the surface, can be a propagation point for cracks. When the material is hot worked the inclusions tend to flow with the contour of the surface, creating stringers. As a whole the strings create a flow structure, where the properties are anisotropic (different based on direction). With the stringers oriented parallel to the surface it strengthens the workpiece, especially with respect to fracturing. The stringers act as "crack-arrestors" because the crack will want to propagate through the stringer and not along it.
The disadvantages are:
*Undesirable reactions between the metal and the surrounding atmosphere (scaling or rapid oxidation of the workpiece)
*Less precise tolerances due to thermal contraction and warping from uneven cooling
*Grain structure may vary throughout the metal for various reasons
*Requires a heating unit of some kind such as a gas or diesel furnace or an induction heater, which can be very expensive | 0 | Metallurgy |
*ISO.15730:2000 Metallic and other Inorganic Coatings - Electropolishing as a Means of Smoothing and Passivating Stainless Steel
*ASME BPE Standards for Electropolishing Bioprocessing Equipment
*SEMI F19, Electropolishing Specifications for Semiconductor Applications
*ASTM B 912-02 (2008), Passivation of Stainless Steels Using Electropolishing
*ASTM E1558, Standard Guide for Electrolytic Polishing of Metallographic Specimens | 0 | Metallurgy |
The reducing atmosphere, rich in CO and H, can be created from the high-temperature cracking of natural gas at around 1100-1150 °C, in the presence of oxidized gases (HO and CO) from ore reduction reactors.
+ CO → 2 CO + H</small>
+ HO → CO + 3 H</small>
The system that generates the reducing gases is called a "reformer". In the Midrex process, it consists of tubes heated by the combustion of a portion (around a third) of the gas from the reactor. | 0 | Metallurgy |
McQuillan was awarded the Rosenhain Medal in 1965. She was on the Interservices Metallurgical Research Council until 1989 and in 1967 served as vice-president of the Institute of Metals. In 1968 she was fundamental to the First International Conference on Titanium in London. | 0 | Metallurgy |
Substantial decreases in extracellular Ca ion concentrations may result in a condition known as hypocalcemic tetany, which is marked by spontaneous motor neuron discharge. In addition, severe hypocalcaemia will begin to affect aspects of blood coagulation and signal transduction.
Ca ions can damage cells if they enter in excessive numbers (for example, in the case of excitotoxicity, or over-excitation of neural circuits, which can occur in neurodegenerative diseases, or after insults such as brain trauma or stroke). Excessive entry of calcium into a cell may damage it or even cause it to undergo apoptosis, or death by necrosis. Calcium also acts as one of the primary regulators of osmotic stress (osmotic shock). Chronically elevated plasma calcium (hypercalcemia) is associated with cardiac arrhythmias and decreased neuromuscular excitability. One cause of hypercalcemia is a condition known as hyperparathyroidism. | 1 | Gene expression + Signal Transduction |
*Isaaks, Edward H., and Srivastava, R. Mohan. An Introduction to Applied Geostatistics. Oxford University Press, Oxford, NY, USA, 1989.
*David, M., Handbook of Applied Advanced Geostatistical Ore Reserve Estimation. Elsevier, Amsterdam, 1988.
*Mineral Processing Plant Design, Practice, and Control - Proceedings. Ed. Mular, A., Halbe, D., and Barratt, D. Society for Mining, Metallurgy, and Exploration, Inc. 2002.
*Mineral Comminution Circuits - Their Operation and Optimisation. Ed. Napier-Munn, T.J., Morrell, S., Morrison, R.D., and Kojovic, T. JKMRC, The University of Queensland, 1996 | 0 | Metallurgy |
The natural selection power for dephosphorylation is less understood. A recent study has found that IRF9, which is from the interferon-regulatory factors family (IRFs), a critical family for anti-viral immune response, could be influenced by natural selection during Human species evolution. The positive selection has been found on the amino acid site Val129 (NP_006075.3:p.Ser129Val) of human IRF9. The ancestral state (Ser129) is conserved among mammals, while the novel state (Val129) was fixed before the "out-of-Africa" event ~ 500,000 years ago. This young amino acid (Val129) may serve as a dephosphorylation site of IRF9. The dephosphorylation may affect the immune activity of IRF9. | 1 | Gene expression + Signal Transduction |
Induction of proliferation by the EpoR is likely cell type-dependent. It is known that EpoR can activate mitogenic signaling pathways and can lead to cell proliferation in erythroleukemic cell lines in vitro, various non-erythroid cells, and cancer cells. So far, there is no sufficient evidence that in vivo, EpoR signaling can induce erythroid progenitors to undergo cell division, or whether Epo levels can modulate the cell cycle. EpoR signaling may still have a proliferation effect upon BFU-e progenitors, but these progenitors cannot be directly identified, isolated and studied. CFU-e progenitors enter the cell cycle at the time of GATA-1 induction and PU.1 suppression in a developmental manner rather than due to EpoR signaling. Subsequent differentiation stages (proerythroblast to orthochromatic erythroblast) involve a decrease in cell size and eventual expulsion of the nucleus, and are likely dependent upon EpoR signaling only for their survival. In addition, some evidence on macrocytosis in hypoxic stress (when Epo can increase 1000-fold) suggests that mitosis is actually skipped in later erythroid stages, when EpoR expression is low/absent, in order to provide emergency reserve of red blood cells as soon as possible. Such data, though sometimes circumstantial, argue that there is limited capacity to proliferate specifically in response to Epo (and not other factors). Together, these data suggest that EpoR in erythroid differentiation may function primarily as a survival factor, while its effect on the cell cycle (for example, rate of division and corresponding changes in the levels of cyclins and Cdk inhibitors) in vivo awaits further work. In other cell systems, however, EpoR may provide a specific proliferative signal. | 1 | Gene expression + Signal Transduction |
The expression of genes in the operon is controlled by three differentially regulated promoters, two of which are controlled by RpoS encoded sigma factor σ.
* csiD : is σ-dependent and is activated exclusively upon carbon starvation because cAMP-CRP acts an essential activator for σ containing RNA polymerase at the csiD promoter.
* gabD: is σ -dependent and is induced by multiple stresses.
* gabD: is σ dependent and is controlled by Nac (Nitrogen Assimilation Control) regulatory proteins expressed under nitrogen limitation. | 1 | Gene expression + Signal Transduction |
Senapathy analyzed the distribution of the ORF lengths in computer-generated random DNA sequences first. Surprisingly, this study revealed that about 200 codons (600 bases) was the upper limit in ORF lengths. The shortest ORF (zero base in length) was the most frequent. At increasing lengths of ORFs, their frequency decreased logarithmically, approaching zero at about 600 bases. When the probability of ORF lengths in a random sequence was plotted, it revealed that the probability of increasing lengths of ORFs decreased exponentially and tailed off at a maximum of about 600 bases. From this “negative exponential” distribution of ORF lengths, it was found that most of ORFs were far shorter than the maximum.This finding was surprising because the coding sequence for the average protein length of 400 AAs (with ~1,200 bases of coding sequence) and longer proteins of thousands of AAs (requiring >10,000 bases of coding sequence) would not occur at a stretch in a random sequence. If this was true, a typical gene with a contiguous coding sequence could not originate in a random sequence. Thus, the only possible way that any gene could originate from a random sequence was to split the coding sequence into shorter segments and select these segments from short ORFs available in the random sequence, rather than to increase the ORF length by eliminating consecutive stop codons. This process of choosing short segments of coding sequences from the available ORFs to make a long ORF would lead to a split structure.
If this hypothesis was true, eukaryotic DNA sequences should reflect it. When Senapathy plotted the distribution of ORF lengths in eukaryotic DNA sequences, the plot was remarkably similar to that from random DNA sequences. This plot was also a negative exponential distribution that tailed off at a maximum of about 600 bases, as with eukaryotic genes, which coincided exactly with the maximum length of ORFs observed in both random DNA and eukaryotic DNA sequences.
The split genes thus originated from random DNA sequences by choosing the best of the short coding segments (exons) and splicing them. The intervening intron sequences were left-over vestiges of the random sequences, and thus were earmarked to be removed by the spliceosome. These findings indicated that split genes could have originated from random DNA sequences with exons and introns as they appear in today's eukaryotic organisms. Nobel Laureate Marshall Nirenberg, who deciphered the codons, stated that these findings strongly showed that the split gene theory for the origin of introns and the split structure of genes must be valid.
Blake proposed the Gilbert-Blake hypothesis in 1979 for the origin of introns and stated that Senapathy's split gene theory comprehensively explained the origin of the split gene structure. In addition, he stated that it explained several key questions including the origin of the splicing mechanism: | 1 | Gene expression + Signal Transduction |
cAMP-dependent protein kinase type I-alpha regulatory subunit is an enzyme that in humans is encoded by the PRKAR1A gene. | 1 | Gene expression + Signal Transduction |
# Magnetic materials e.g. alnico, sendust, Permendur, FeCo, Terfenol-D
# Superconductors e.g. A15 phases, niobium-tin
# Hydrogen storage e.g. AB compounds (nickel metal hydride batteries)
# Shape memory alloys e.g. Cu-Al-Ni (alloys of CuAl and nickel), Nitinol (NiTi)
# Coating materials e.g. NiAl
# High-temperature structural materials e.g. nickel aluminide, NiAl
# Dental amalgams, which are alloys of intermetallics AgSn and CuSn
# Gate contact/ barrier layer for microelectronics e.g. TiSi
# Laves phases (AB), e.g., MgCu, MgZn and MgNi.
The formation of intermetallics can cause problems. For example, intermetallics of gold and aluminium can be a significant cause of wire bond failures in semiconductor devices and other microelectronics devices. The management of intermetallics is a major issue in the reliability of solder joints between electronic components. | 0 | Metallurgy |
Defects in the erythropoietin receptor may produce erythroleukemia and familial erythrocytosis. Overproduction of red blood cells increases a chance of adverse cardiovascular event, such as thrombosis and stroke.
Rarely, seemingly beneficial mutations in the EpoR may arise, where increased red blood cell number allows for improved oxygen delivery in athletic endurance events with no apparent adverse effects upon the athlete's health (as for example in the Finnish athlete Eero Mäntyranta).
Erythropoietin was reported to maintain endothelial cells and to promote tumor angiogenesis, hence the dysregulation of EpoR may affect the growth of certain tumors. However this hypothesis is not universally accepted. | 1 | Gene expression + Signal Transduction |
It was previously thought that it was the relatively small RNA polymerase that moves along the comparatively larger DNA template during transcription. However, increasing evidence supports the notion that due to the tethering of a transcription factory to the nuclear matrix, it is in fact the large DNA template that is moved to accommodate RNA polymerisation. In vitro studies for example have shown that RNA polymerases attached to a surface are capable of both rotating the DNA template and threading it through the polymerase to start transcription; which indicates the capabilities of RNA polymerase to be a molecular motor. Chromosome Conformation Capture (3C) also supports the idea of the DNA template diffusing towards a stationary RNA polymerase.
There remains a doubt to this mechanism of transcription. Firstly, it is unknown how a stationary polymerase is capable of transcribing genes on the (+)-strand and (-)-strand at the same genomic locus at the same time. This is in addition to a lack of conclusive evidence on how the polymerase remains immobilised (how it is tethered) and what structure it is tethered to. | 1 | Gene expression + Signal Transduction |
Dunne completed a Bachelor of Science and Master of Engineering degree from the Department of Mechanical Engineering, University of Bristol by 1989, and moved to the Department of Mechanical and Process Engineering, University of Sheffield, for a Doctor of Philosophy in Computer Aided Modelling of Creep-cyclic Plasticity Interaction in Engineering Materials and Structures. | 0 | Metallurgy |
In this technique it is necessary to select a suitable interlayer by considering its wettability, flow characteristics, high stability to prevent reactions with the base materials, and the ability to form a composition having a remelt temperature higher than the bonding temperature. The joining technique dates back to ancient times.
For example, copper oxide painted as an interlayer and covered with tallow or glue to hold gold balls on to a gold article were heated in a reducing flame to form a eutectic alloy alloy at the bond area. | 0 | Metallurgy |
One of the best-known ironmasters of the early part of the industrial revolution was John Wilkinson (1728–1808), who was considered to have "iron madness", extending even to making cast iron coffins. Wilkinsons patented method for boring iron cylinders was first used to create cannons, but later provided the precision needed to create James Watts first steam engines. | 0 | Metallurgy |
The mineral was recorded in 1955 on three bronze artifacts from ancient Egypt, which were being held in the Fogg Art Museum at Harvard. Chalconatronite was found inside of two bronze figures (one depicting a seated Sekhmet, and another one depicting a group of cats and kittens) from around the late Nubian Dynasty or early Saite Period. Another chalconatronite specimen was found under a bronze censer from the late Coptic Period. The chalconatronite found on the censer formed over cuprite and some atacamite crystals, which are associated minerals.
Chalconatronite was also found on iron and copper Roman armor in 1982 at a site in Chester, England. Some of the mineral was found on a copper pin in St. Mark's Basilica, Venice and in two different Mayan paintings. Along with pseudomalachite, chalconatronite was found on an illuminated manuscript from the sixteenth century. Synthetic chalconatronite could have possibly been made in ancient China as a form of pigment, named "synthetic malachite". It was made by taking copper oxide and boiling it with white alum in a "sufficient amount of water". After the result is cooled, a natron solution would be added to precipitate a synthetic form of chalconatronite, as sodium copper carbonate. | 0 | Metallurgy |
The detection of eRNAs is fairly recent (2010) and has been made possible through the use of genome-wide investigation techniques such as RNA sequencing (RNA-seq) and chromatin immunoprecipitation-sequencing (ChIP-seq). RNA-seq permits the direct identification of eRNAs by matching the detected transcript to the corresponding enhancer sequence through bioinformatic analyses. ChIP-seq represents a less direct way to assess enhancer transcription but can also provide crucial information as specific chromatin marks are associated with active enhancers. Although some data remain controversial, the consensus in the literature is that the best combination of histone post-translational modifications at active enhancers is made of H2AZ, H3K27ac, and a high ratio of H3K4me1 over H3K4me3. ChIP experiments can also be conducted with antibodies that recognize RNA Pol II, which can be found at sites of active transcription. The experimental detection of eRNAs is complicated by their low endogenous stability conferred by exosome degradation and nonsense-mediated decay. A comparative study showed that assays enriching for capped and nascent RNAs (with strategies like nuclei run-on and size selection) could capture more eRNAs compared to canonical RNA-seq. These assays include Global/Precision Run-on with cap-selection (GRO/PRO-cap), capped-small RNA-seq (csRNA-seq), Native Elongating Transcript-Cap Analysis of Gene Expression (NET-CAGE), and Precision Run-On sequencing (PRO-seq). Nonetheless, the fact that eRNAs tend to be expressed from active enhancers might make their detection a useful tool to distinguish between active and inactive enhancers. | 1 | Gene expression + Signal Transduction |
In the years up to 1960 the following approximate division of Fulmer's income applied: about 25% of project work was for UK Government defence agencies; 25% for the Atomic Energy Authority and another 10% for other Government agencies. About 10% was for US Government agencies (the US Air Force and the Office of Aerospace Research); 30% was for British Industry. | 0 | Metallurgy |
The puddling furnace is a metalmaking technology used to create wrought iron or steel from the pig iron produced in a blast furnace. The furnace is constructed to pull the hot air over the iron without the fuel coming into direct contact with the iron, a system generally known as a reverberatory furnace or open hearth furnace. The major advantage of this system is keeping the impurities of the fuel separated from the charge.
The hearth is where the iron is charged, melted and puddled. The hearth's shape is usually elliptical; in length and wide. If the furnace is designed to puddle white iron then the hearth depth is never more than . If the furnace is designed to boil gray iron then the average hearth depth is . Due to the great heat required to melt the charge the grate had to be cooled, lest it melt with the charge. This was done by running a constant flow of cool air on it, or by throwing water on the bottom of the grate.
The fireplace, where the fuel is burned, used a cast iron grate which varied in size depending on the fuel used. If bituminous coal is used then an average grate size is and is loaded with of coal. If anthracite coal is used then the grate is and is loaded with of coal.
A double puddling furnace is similar to a single puddling furnace, with the major difference being there are two work doors allowing two puddlers to work the furnace at the same time. The biggest advantage of this setup is that it produces twice as much wrought iron. It is also more economical and fuel efficient compared to a single furnace. | 0 | Metallurgy |
E74-like factor 1 (ets domain transcription factor) is a protein that in humans is encoded by the ELF1 gene. | 1 | Gene expression + Signal Transduction |
Although in the aforementioned example, oxic conditions were always considered with the reduction of dissolved in the cathodic zones, pitting corrosion may also occur under anoxic, or reducing, conditions. Indeed, the very harmful reduced species of sulfur (, , , , , S and ) can only subsist under reducing conditions. Moreover, in the case of steel and stainless steel, reducing conditions are conducive to the dissolution of the protective oxide layer (dense γ-) because is much more soluble than , and so reducing conditions contribute to the breakdown of the protective oxide layer (initiation, nucleation of the pit). Reductants exert thus an antagonist effect with respect to the oxidants (chromate, nitrite) used as corrosion inhibitors to induce steel repassivation via the formation of a dense γ- protective layer. Pitting corrosion can thus occur both under oxidizing and reducing conditions and can be aggravated in poorly oxygenated waters by differential aeration, or by drying/wetting cycles.
Under strongly reducing conditions, in the absence of dissolved oxygen in water, or pore water of the ground, the electron acceptor (oxidizing agent) at the cathodic sites, where reduction occurs, can be the protons () of water itself, the protons of hydrogen sulfide (), or in acidic conditions in case of severe pyrite oxidation in a former oxic atmosphere, dissolved ferric ions (), known to be very potent oxidizers. The presence of harmful reduced species of sulfur and microbial activity feeding the sulfur cycle (sulfide oxidation possibly followed by bacterial sulfate reduction) have also to be taken into account. Strictly abiotic (i.e. inorganic) corrosion processes are generally slower under anoxic conditions than under oxic conditions, but the presence of bacteria and biofilms can aggravate the degradation conditions and causes unexpected problems. Critical infrastructures and metallic components with very long service life may be susceptible to pitting corrosion: for example the metallic canisters and overpacks aimed to contain vitrified high-level radioactive waste (HLW) and spent nuclear fuel and to confine them in a water-tight enveloppe for several tenths of thousands years in deep geologic repositories. | 0 | Metallurgy |
The shutter in the closed position fits within the window casement. This was the prevalent approach in the Colonies from New York and south. An advantage is the additional security because the shutters can not be lifted from the pintles in the closed position. A disadvantage is that the shutters must be matched closely to the inside dimension of the casing and the shutter rabbet should match the thickness of the shutters.
Any surface mounted hinge and pintle can be used, assuming there is sufficient width to the casing to accept the pintle. The hinge has a minimal standoff and the pintle would have the same matching standoff. Together an offset of 1–1½ inches will hold the shutter at the same distance from the structure and not quite parallel to the wall. | 0 | Metallurgy |
Nod factors (nodulation factors or NF), are signaling molecules produced by soil bacteria known as rhizobia in response to flavonoid exudation from plants under nitrogen limited conditions. Nod factors initiate the establishment of a symbiotic relationship between legumes and rhizobia by inducing nodulation. Nod factors produce the differentiation of plant tissue in root hairs into nodules where the bacteria reside and are able to fix nitrogen from the atmosphere for the plant in exchange for photosynthates and the appropriate environment for nitrogen fixation. One of the most important features provided by the plant in this symbiosis is the production of leghemoglobin, which maintains the oxygen concentration low and prevents the inhibition of nitrogenase activity. | 1 | Gene expression + Signal Transduction |
The term depletion gilding usually refers to the production of a layer of gold. However, it can also be used to produce a layer that is an alloy of gold and silver, sometimes referred to as electrum. Certain chemicals, such as oxalic acid, attack copper but do not affect either silver or gold. Using such a chemical, it is possible to remove only the copper in an alloy, leaving both silver and the gold behind. Thus, if the original object is composed of copper, silver, and gold, it can be given a gold surface by removing both silver and copper, or an electrum surface by removing only the copper.
Likewise, with an appropriate chemical, a layer of nearly pure silver can be produced on an object made of copper and silver. For instance, sterling silver can be depleted—depletion silvering—to produce a fine silver surface, perhaps as preamble to application of gold, as in the Keum-boo technique.
However, in the majority of cases depletion gilding is in fact used to produce a gold finish, rather than one of electrum or silver. | 0 | Metallurgy |
C6; C7; 8A; 8B; C9; CD320; CFI;
CORIN; DGCR2; HSPG2; LDLR; LDLRAD2; LDLRAD3; LRP1; LRP10;
LRP11; LRP12; LRP1B; LRP2; LRP3; LRP4; LRP5; LRP6;
LRP8; MAMDC4; MFRP; PRSS7; RXFP1; RXFP2; SORL1; SPINT1;
SSPO; ST14; TMPRSS4; TMPRSS6; TMPRSS7; TMPRSS9 (serase-1B); VLDLR; | 1 | Gene expression + Signal Transduction |
Subsets and Splits