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Degenerate matter Quark-degenerate matter may occur in the cores of neutron stars, depending on the equations of state of neutron-degenerate matter. It may also occur in hypothetical quark stars, formed by the collapse of objects above the Tolman–Oppenheimer–Volkoff mass limit for neutron-degenerate objects. Whether qu... | https://en.wikipedia.org/wiki?curid=144428 |
Degenerate matter ) It is a general result of quantum mechanics that no fermion can be confined in a space smaller than its own wavelength, making such a singularity impossible, unless only bosons are present, but there is no widely accepted theory that combines general relativity and quantum mechanics sufficiently to ... | https://en.wikipedia.org/wiki?curid=144428 |
Bhopal disaster The Bhopal disaster, also referred to as the Bhopal gas tragedy, was a gas leak incident on the night of 2–3 December 1984 at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh, India. It is considered to be the world's worst industrial disaster. Over 500,000 people were ex... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster In 1989, UCC paid $470 million (equivalent to $ in ) to settle litigation stemming from the disaster. In 1994, UCC sold its stake in UCIL to Eveready Industries India Limited (EIIL), which subsequently merged with McLeod Russel (India) Ltd. Eveready ended clean-up on the site in 1998, when it terminated... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster The chemical process employed in the Bhopal plant had methylamine reacting with phosgene to form MIC, which was then reacted with 1-naphthol to form the final product, carbaryl. Another manufacturer, Bayer, also used this MIC-intermediate process at the chemical plant once owned by UCC at Institute, Wes... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster In January 1982, a phosgene leak exposed 24 workers, all of whom were admitted to a hospital. None of the workers had been ordered to wear protective equipment. One month later, in February 1982, a MIC leak affected 18 workers. In August 1982, a chemical engineer came into contact with liquid MIC, resul... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Shortly after this failure, MIC production was halted at the Bhopal facility, and parts of the plant were shut down for maintenance. Maintenance included the shutdown of the plant's flare tower so that a corroded pipe could be repaired. With the flare tower still out of service, production of carbaryl w... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster , workers in the MIC area were feeling the effects of minor exposure to MIC gas, and began to look for a leak. One was found by 11:45 p.m., and reported to the MIC supervisor on duty at the time. The decision was made to address the problem after a 12:15 a.m. tea break, and in the meantime, employees we... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Activation of the system triggered two siren alarms: one that sounded inside the UCIL plant itself, and a second directed to the exterior, which would alert the public and the city of Bhopal. The two siren systems had been decoupled from one another in 1982, so that it was possible to leave the factory ... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Fifteen minutes later, the plant's public siren was sounded for an extended period of time, after first having been quickly silenced an hour and a half earlier. Some minutes after the public siren sounded, a UCIL employee walked to a police control room to both inform them of the leak (their first ackno... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Findings during autopsies revealed changes not only in the lungs but also cerebral oedema, tubular necrosis of the kidneys, fatty degeneration of the liver and necrotising enteritis. The stillbirth rate increased by up to 300% and neonatal mortality rate by around 200%. Apart from MIC, based on laborato... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Union Carbide organized a team of international medical experts, as well as supplies and equipment, to work with the local Bhopal medical community, and the UCC technical team began assessing the cause of the gas leak. The health care system immediately became overloaded. In the severely affected areas,... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Lacking any safe alternative, on 16 December, tanks 611 and 619 were emptied of the remaining MIC by reactivating the plant and continuing the manufacture of pesticide. Despite safety precautions such as having water-carrying helicopters continually overflying the plant, this led to a second mass evacua... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Keenan (overseeing one lawsuit) suggested that "'fundamental human decency' required Union Carbide to provide between $5 million and $10 million to immediately help the injured" and suggested the money could be quickly distributed through the International Red Cross. UCC, on the notion that doing so did... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster In October 1991, the Supreme Court upheld the original , dismissing any other outstanding petitions that challenged the original decision. The Court ordered the Indian government "to purchase, out of settlement fund, a group medical insurance policy to cover 100,000 persons who may later develop symptom... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster The Second Circuit Court of Appeals in New York City upheld the dismissal of remaining claims in the case of "Bano v. Union Carbide Corporation" in 2006. This move blocked plaintiffs' motions for class certification and claims for property damages and remediation. In the view of UCC, "the ruling reaffir... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster The lawsuit was dismissed in 2012 and the subsequent appeal was denied. Former UCC CEO Anderson, then 92 years old, died on 29 September 2014. In 2018, "The Atlantic" called it the "world’s worst industrial disaster." Some data about the health effects are still not available. The Indian Council of Medi... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster A number of clinical studies are performed. The quality varies, but the different reports support each other. Studied and reported long-term health effects are: Missing or insufficient fields for research are female reproduction, chromosomal aberrations, cancer, immune deficiency, neurological sequelae,... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster BMHRC was a 350-bedded super speciality hospital where heart surgery and hemodialysis were done. There was a dearth of gynaecology, obstetrics and paediatrics. Eight mini-units (outreach health centres) were started and free health care for gas victims were to be offered until 2006. The management had a... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster In December 2008, the Madhya Pradesh High Court decided that the toxic waste should be incinerated at Ankleshwar in Gujarat, which was met by protests from activists all over India. On 8 June 2012, the Centre for incineration of toxic Bhopal waste agreed to pay to dispose of UCIL chemical plants waste i... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster The government also planned 2,486 flats in two- and four-story buildings in what is called the "widow's colony" outside Bhopal. The water did not reach the upper floors and it was not possible to keep cattle which were their primary occupation. Infrastructure like buses, schools, etc. were missing for a... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster By the end of October 2003, according to the Bhopal Gas Tragedy Relief and Rehabilitation Department, compensation had been awarded to 554,895 people for injuries received and 15,310 survivors of those killed. The average amount to families of the dead was $2,200. In 2007, 1,029,517 cases were registere... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster The "Worker Sabotage" point of view argues that it was not physically possible for the water to enter the tank without concerted human effort, and that extensive testimony and engineering analysis leads to a conclusion that water entered the tank when a rogue individual employee hooked a water hose dire... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster This point of view argues that management (and to some extent, local government) underinvested in safety, which allowed for a dangerous working environment to develop. Factors cited include the filling of the MIC tanks beyond recommended levels, poor maintenance after the plant ceased MIC production at ... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Workers were forced to use English manuals, even though only a few had a grasp of the language. Subsequent research highlights a gradual deterioration of safety practices in regard to the MIC, which had become less relevant to plant operations. By 1984, only six of the original twelve operators were sti... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster The flare tower and several vent gas scrubbers had been out of service for five months before the disaster. Only one gas scrubber was operating: it could not treat such a large amount of MIC with sodium hydroxide (caustic soda), which would have brought the concentration down to a safe level. The flare ... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster UCC admitted in their own investigation report that most of the safety systems were not functioning on the night of 3 December 1984. The design of the MIC plant, following government guidelines, was "Indianized" by UCIL engineers to maximise the use of indigenous materials and products. Mumbai-based Hum... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster In September 1984, an internal UCC report on the West Virginia plant in the USA revealed a number of defects and malfunctions. It warned that "a runaway reaction could occur in the MIC unit storage tanks, and that the planned response would not be timely or effective enough to prevent catastrophic failu... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Little report concluded that it was likely that a single employee secretly and deliberately introduced a large amount of water into the MIC tank by removing a meter and connecting a water hose directly to the tank through the metering port. UCC claims the plant staff falsified numerous records to distan... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster He alleged that Verma was unhappy with Chaudhary and Mukund. The corporation denied the claim that the valves on the tank were malfunctioning, and claimed that the documented evidence gathered after the incident showed that the valve close to the plant's water-washing operation was closed and was leak-t... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Financial response The primary financial restitution paid by UCC was negotiated in 1989, when the Indian Supreme Court approved a settlement of US$470 million (₹1,055 crore; equivalent to $ in ). This amount was immediately paid by UCC to the Indian government. The company states that the restitution pa... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster The hospital catered for the treatment of heart, lung and eye problems. UCC also provided a $2.2 million grant to Arizona State University to establish a vocational-technical center in Bhopal, which was opened, but was later closed by the state government. They also donated $5 million to the Indian Red ... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Contamination at the site and surrounding area was not caused by the gas leakage. The area around the plant was used as a dumping ground for hazardous chemicals and by 1982 water wells in the vicinity of the UCIL factory had to be abandoned. UCC states that "after the incident, UCIL began clean-up work ... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Substances found, according to the reports, are naphthol, naphthalene, Sevin, tarry residues, alpha naphthol, mercury, organochlorines, chromium, copper, nickel, lead, hexachlorethane, hexachlorobutadiene, pesticide HCH (BHC), volatile organic compounds and halo-organics. Many of these contaminants were... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster A drinking water sample from a well near the site had levels of contamination 500 times higher than the maximum limits recommended by the World Health Organization. In 2009, the Centre for Science and Environment, a Delhi-based pollution monitoring lab, released test results showing pesticide groundwate... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster The book is based on Malladi's recollections of Bhopal during the incident. Indra Sinha released "Animal's People" in 2007. The novel tells the story of a boy who is born with a spinal condition due to effects of the gas. The book was shortlisted for the Man Booker Prize. Arundhati Roy's 2017 novel "The... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster The activists worked on organising the gas victims, which led to violent repression from the police and the government. Numerous actions have been performed: demonstrations, sit-ins, hunger strikes, marches combined with pamphlets, books, and articles. Every anniversary, actions are performed. Often the... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster More than 15 national organisations have been engaged along with a number of international organisations. Some of the organisations are: On 3 December 2004, the twentieth anniversary of the disaster, a man falsely claiming to be a Dow representative named Jude Finisterra was interviewed on BBC World New... | https://en.wikipedia.org/wiki?curid=144638 |
Bhopal disaster Journalists, film-makers and authors who were investigating Bhopal and covering the issue of ongoing contamination, such as Jack Laurenson and Max Carlson, were also placed under surveillance. Stratfor released a statement condemning the revelation by Wikileaks while neither confirming nor denying the a... | https://en.wikipedia.org/wiki?curid=144638 |
Brisance is the shattering capability of a high explosive, determined mainly by its detonation pressure. The term can be traced from the French verb "briser" (to break or shatter) ultimately derived from the Celtic word "brissim" (to break). is of practical importance for determining the effectiveness of an explosion i... | https://en.wikipedia.org/wiki?curid=144843 |
Brisance In shattering hard rock or military defences, brisance generally is necessary, so high explosives with extremely high detonation velocity are used as far as is practical. Fragmentation occurs by the action of the transmitted shock wave, the strength of which depends on the detonation pressure of the explosive.... | https://en.wikipedia.org/wiki?curid=144843 |
Boron group The boron group are the chemical elements in group 13 of the periodic table, comprising boron (B), aluminium (Al), gallium (Ga), indium (In), thallium (Tl), and perhaps also the chemically uncharacterized nihonium (Nh). The elements in the boron group are characterized by having three valence electrons. The... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group Thallium is highly toxic, interfering with the function of numerous vital enzymes, and has seen use as a pesticide. Like other groups, the members of this family show patterns in electron configuration, especially in the outermost shells, resulting in trends in chemical behavior: The boron group is notable ... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group Indium, the next element in the group, is not known to form many hydrides, except in complex compounds such as the phosphine complex HInP(Cy). No stable compound of thallium and hydrogen has been synthesized in any laboratory. All of the boron-group elements are known to form a trivalent oxide, with two ato... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group All of the elements will react with bromine under the right conditions, as with the other halogens but less vigorously than either chlorine or fluorine. Iodine will react with all natural elements in the periodic table except for the noble gases, and is notable for its explosive reaction with aluminium to f... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group The inert s-pair effect is significant in the group-13 elements, especially the heavier ones like thallium. This results in a variety of oxidation states. In the lighter elements, the +3 state is the most stable, but the +1 state becomes more prevalent with increasing atomic number, and is the most stable f... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group All of these isotopes are readily found in macroscopic quantities in nature. In theory, though, all isotopes with an atomic number greater than 66 are supposed to be unstable to alpha decay. Conversely, all elements with atomic numbers are less than or equal to 66 (except Tc, Pm, Sm and Eu) have at least on... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group The latter name is derived from the Latin prefix "tri-" ("three") and refers to the three valence electrons that all of these elements, without exception, have in their valence shells. Boron was known to the ancient Egyptians, but only in the mineral borax. The metalloid element was not known in its pure fo... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group The first pure sample of aluminium is credited to Henri Etienne Sainte-Claire Deville, who substituted sodium for potassium in the procedure. At that time aluminium was considered precious, and it was displayed next to such metals as gold and silver. The method used today, electrolysis of aluminium oxide di... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group Reich heated the ore in a coil of platinum metal and observed the lines that appeared in a spectroscope. Instead of the green thallium lines that he expected, he saw a new line of deep indigo-blue. Concluding that it must come from a new element, they named it after the characteristic indigo color it had pr... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group The results were published in January of the following year. Since then around 13 atoms have been synthesized and various isotopes characterized. However, their results did not meet the stringent criteria for being counted as a discovery, and it was the later RIKEN experiments of 2004 aimed at directly synt... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group It is known to occur in over a hundred different minerals and ores, however: the main source is borax, but it is also found in colemanite, boracite, kernite, tusionite, berborite and fluoborite. Major world miners and extractors of boron include the United States, Turkey, Argentina, China, Bolivia and Peru.... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group Gallium can be found as a trace in a variety of ores, including bauxite and sphalerite, and in such minerals as diaspore and germanite. Trace amounts have been found in coal as well. The gallium content is greater in a few minerals, including gallite (CuGaS), but these are too rare to be counted as major so... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group In minerals it is found in moderate quantities: some examples are crookesite (in which it was first discovered), lorandite, routhierite, bukovite, hutchinsonite and sabatierite. There are other minerals that contain small amounts of thallium, but they are very rare and do not serve as primary sources. Nihon... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group Aluminium is a metal with numerous familiar uses in everyday life. It is most often encountered in construction materials, in electrical devices, especially as the conductor in cables, and in tools and vessels for cooking and preserving food. Aluminium's lack of reactivity with food products makes it partic... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group Gallium has the property of being able to 'wet' glass and porcelain, and thus can be used to make mirrors and other highly reflective objects. Gallium can be added to alloys of other metals to lower their melting points. Indium's uses can be divided into four categories: the largest part (70%) of the produc... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group Thallium hydroxide (TlOH) is used mainly in the production of other thallium compounds. Thallium sulfate (TlSO) is an outstanding vermin-killer, and it is a principal component in some rat and mouse poisons. However, the United States and some European countries have banned the substance because of its high... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group Indium and its heavier homologues have no biological role, although indium salts in small doses, like gallium, can stimulate metabolism. All of the elements in the boron group can be toxic, given a high enough dose. Some of them are only toxic to plants, some only to animals, and some to both. As an example... | https://en.wikipedia.org/wiki?curid=144929 |
Boron group The incidence of thallium poisoning, intentional and accidental, increased when thallium (with its similarly toxic compound, thallium sulfate) was introduced to control rats and other pests. The use of thallium pesticides has therefore been prohibited since 1975 in many countries, including the USA. Nihoniu... | https://en.wikipedia.org/wiki?curid=144929 |
Sintering or frittage is the process of compacting and forming a solid mass of material by heat or pressure without melting it to the point of liquefaction. happens naturally in mineral deposits or as a manufacturing process used with metals, ceramics, plastics, and other materials. The atoms in the materials diffuse a... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering During the firing process, atomic diffusion drives powder surface elimination in different stages, starting from the formation of necks between powders to final elimination of small pores at the end of the process. The driving force for densification is the change in free energy from the decrease in surface a... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering This energy creates a transfer of material through the fastest means possible; if transfer were to take place from the particle volume or the grain boundary between particles, then there would be particle reduction and pore destruction. The pore elimination occurs faster for a trial with many pores of uniform... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering , tails and frits) can be easily obtained by observing the expansion-temperature curves during optical dilatometer thermal analysis. In fact, sinterisation is associated with a remarkable shrinkage of the material because glass phases flow once their transition temperature is reached, and start consolidating ... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering under atmospheric pressure requires the use of a protective gas, quite often endothermic gas. Sintering, with subsequent reworking, can produce a great range of material properties. Changes in density, alloying, and heat treatments can alter the physical characteristics of various products. For instance, the ... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering Liquid-state sintering is required for making cemented carbide and tungsten carbide. Sintered bronze in particular is frequently used as a material for bearings, since its porosity allows lubricants to flow through it or remain captured within it. Sintered copper may be used as a wicking structure in certain ... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering of powders containing precious metals such as silver and gold is used to make small jewelry items. Particular advantages of the powder technology include: The literature contains many references on sintering dissimilar materials to produce solid/solid-phase compounds or solid/melt mixtures at the processing s... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering Liquid phase sintering is the process of adding an additive to the powder which will melt before the matrix phase. The process of liquid phase sintering has three stages: For liquid phase sintering to be practical the major phase should be at least slightly soluble in the liquid phase and the additive should ... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering In the United States, sintering was first patented by Duval d’Adrian in 1922. His three-step process aimed at producing heat-resistant blocks from such oxide materials as zirconia, thoria or tantalia. The steps were: (i) molding the powder; (ii) annealing it at about 2500 °C to make it conducting; (iii) apply... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering For a number of years, it was speculated that the existence of sparks or plasma between particles could aid sintering; however, Hulbert and coworkers systematically proved that the electric parameters used during spark plasma sintering make it (highly) unlikely. In light of this, the name "spark plasma sinter... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering Pressureless sintering is the sintering of a powder compact (sometimes at very high temperatures, depending on the powder) without applied pressure. This avoids density variations in the final component, which occurs with more traditional hot pressing methods. The powder compact (if a ceramic) can be created ... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering Although this should prevent separation of pores from grain boundaries, it has been proven statistically that RCS did not produce smaller grain sizes than CRH for alumina, zirconia, and ceria samples. Two-step sintering (TSS) uses two different sintering temperatures. The first sintering temperature should gu... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering As microwaves can only penetrate a short distance in materials with a high conductivity and a high permeability, microwave sintering requires the sample to be delivered in powders with a particle size around the penetration depth of microwaves in the particular material. The sintering process and side-reactio... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering This phenomenon, known as Abnormal grain growth, or AGG results in a bimodal grain size distribution which has consequences on the mechanical performance of the sintered object. For densification to occur at a quick pace it is essential to have (1) an amount of liquid phase that is large in size, (2) a near c... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering The sintering of liquid-phase materials involves a fine-grained solid phase to create the needed capillary pressures proportional to its diameter, and the liquid concentration must also create the required capillary pressure within range, else the process ceases. The vitrification rate is dependent upon the p... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering A grain boundary(GB) is the transition area or interface between adjacent crystallites (or grains) of the same chemical and lattice composition, not to be confused with a phase boundary. The adjacent grains do not have the same orientation of the lattice, thus giving the atoms in GB shifted positions relative... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering “Or, in other words, a force has to be applied, in the plane of the grain boundary and acting along a line in the grain-boundary area, in order to extend the grain-boundary area in the direction of the force. The force per unit length, i.e. tension/stress, along the line mentioned is σGB. On the basis of this... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering dG is given by formula_6 which gives formula_7 formula_2 is normally expressed in units of formula_9 while formula_3 is normally expressed in units of formula_11 formula_12 since they are different physical properties. In a two-dimensional isotropic material the grain boundary tension would be the same for th... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering This means that the grain boundary will migrate towards the curvature. The consequence of this is that grains with less than 6 sides will decrease in size while grains with more than 6 sides will increase in size. Grain growth occurs due to motion of atoms across a grain boundary. Convex surfaces have a highe... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering The original concentration of solute around the grain boundary will be asymmetrical in most cases. As the grain boundary tries to move, the concentration on the side opposite of motion will have a higher concentration and therefore have a higher chemical potential. This increased chemical potential will act a... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering So the number of particles n intersecting a unit area of grain boundary is: formula_17 Now, assuming that the grains only grow due to the influence of curvature, the driving force of growth is formula_18 where (for homogeneous grain structure) R approximates to the mean diameter of the grains. With this the c... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering Altering of wall rocks can also form sinters near fumaroles and in the deeper channels of hot springs. Examples of siliceous sinter are geyserite and fiorite. They can be found in many places, including Iceland, El Tatio geothermal field in Chile, New Zealand, and Yellowstone National Park and Steamboat Sprin... | https://en.wikipedia.org/wiki?curid=145020 |
Sintering Rare-earth metals in particular have been shown to reduce sintering of metal catalysts when alloyed. For many supported metal catalysts, sintering starts to become a significant effect at temperatures over . Catalysts that operate at higher temperatures, such as a car catalyst, use structural improvements to ... | https://en.wikipedia.org/wiki?curid=145020 |
Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. The field is a materials science, covering all aspects of the types of ore, washing, concentration, separation, chemical processes and extraction of pure me... | https://en.wikipedia.org/wiki?curid=145066 |
Extractive metallurgy , whereby the impurities and unwanted materials are removed from the ore and the base ore of the metal is concentrated, meaning the percentage of metal in the ore is increased. This concentrate is then either processed to remove moisture or else used as is for extraction of the metal or made into ... | https://en.wikipedia.org/wiki?curid=145066 |
Extractive metallurgy More often, the ore must be pretreated by various mineral processing steps, and sometimes by pyrometallurgical processes. Pyrometallurgy involves high temperature processes where chemical reactions take place among gases, solids, and molten materials. Solids containing valuable metals are treated ... | https://en.wikipedia.org/wiki?curid=145066 |
Extractive metallurgy The metal of interest is plated onto the cathode, while the anode is an inert electrical conductor. Electro-refining is used to dissolve an impure metallic anode (typically from a smelting process) and produce a high purity cathode. Fused salt electrolysis is another electrometallurgical process w... | https://en.wikipedia.org/wiki?curid=145066 |
Metallic hydrogen is a phase of hydrogen in which it behaves like an electrical conductor. This phase was predicted in 1935 on theoretical grounds by Eugene Wigner and Hillard Bell Huntington. At high pressure and temperatures, metallic hydrogen can exist as a liquid rather than a solid, and researchers think it might ... | https://en.wikipedia.org/wiki?curid=145197 |
Metallic hydrogen Since the first work by Wigner and Huntington, the more modern theoretical calculations point towards higher but nonetheless potentially accessible metallization pressures of around . Helium-4 is a liquid at normal pressure near absolute zero, a consequence of its high zero-point energy (ZPE). The ZPE... | https://en.wikipedia.org/wiki?curid=145197 |
Metallic hydrogen Metastable metallic hydrogen may have potential as a highly-efficient rocket propellant, with a theoretical specific impulse of up to 1700 seconds, though a metastable form suitable for mass-production and conventional high-volume storage may not exist. Presently known "super" states of matter are sup... | https://en.wikipedia.org/wiki?curid=145197 |
Metallic hydrogen This was later verified in AcH and LaH with Tc approaching 270K leading to speculation that other compounds may even be stable at mere MPa pressures with room temperature superconductivity. In March 1996, a group of scientists at Lawrence Livermore National Laboratory reported that they had serendipit... | https://en.wikipedia.org/wiki?curid=145197 |
Metallic hydrogen Because the thermal energy of the fluid (the temperature became about due to compression of the sample) was above , the hydrogen might be considered metallic. Many experiments are continuing in the production of metallic hydrogen in laboratory conditions at static compression and low temperature. Arth... | https://en.wikipedia.org/wiki?curid=145197 |
Metallic hydrogen This claim was questioned by other researchers in 2012. In 2015, scientists at the Z Pulsed Power Facility announced the creation of metallic deuterium using dense liquid deuterium, an electrical insulator-to-conductor transition associated with an increase in optical reflectivity. On 5 October 2016, ... | https://en.wikipedia.org/wiki?curid=145197 |
Metallic hydrogen In February 2017, it was reported that the sample of claimed metallic hydrogen was lost, after the diamond anvils it was contained between broke. In August 2017, Silvera and Dias issued an erratum to the "Science" article, regarding corrected reflectance values due to variations between the optical de... | https://en.wikipedia.org/wiki?curid=145197 |
Rare-earth element A rare-earth element (REE) or rare-earth metal (REM), as defined by the International Union of Pure and Applied Chemistry, is one of a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides, as well as scandium and yttrium. Scandium and yttrium are considered r... | https://en.wikipedia.org/wiki?curid=145440 |
Rare-earth element The first rare-earth mineral discovered (1787) was gadolinite, a mineral composed of cerium, yttrium, iron, silicon, and other elements. This mineral was extracted from a mine in the village of Ytterby in Sweden; four of the rare-earth elements bear names derived from this single location. A table li... | https://en.wikipedia.org/wiki?curid=145440 |
Rare-earth element Thus by 1803 there were two known rare-earth elements, "yttrium" and "cerium", although it took another 30 years for researchers to determine that other elements were contained in the two ores ceria and yttria (the similarity of the rare-earth metals' chemical properties made their separation difficu... | https://en.wikipedia.org/wiki?curid=145440 |
Rare-earth element Due to the difficulty in separating the metals (and determining the separation is complete), the total number of false discoveries was dozens, with some putting the total number of discoveries at over a hundred. There were no further discoveries for 30 years, and the element didymium was listed in th... | https://en.wikipedia.org/wiki?curid=145440 |
Rare-earth element Harmann proposed that a new element he called "ilmenium" should be present in this mineral, but later, Christian Wilhelm Blomstrand, Galissard de Marignac, and Heinrich Rose found only tantalum and niobium (columbium) in it. The exact number of rare-earth elements that existed was highly unclear, and... | https://en.wikipedia.org/wiki?curid=145440 |
Rare-earth element The plutonium-239 was very desirable because it is a fissile material. The principal sources of rare-earth elements are the minerals bastnäsite, monazite, and loparite and the lateritic ion-adsorption clays. Despite their high relative abundance, rare-earth minerals are more difficult to mine and ext... | https://en.wikipedia.org/wiki?curid=145440 |
Rare-earth element The reason for this division arose from the difference in solubility of rare-earth double sulfates with sodium and potassium. The sodium double sulfates of the cerium group are difficultly soluble, those of the terbium group slightly, and those of the yttrium group are very soluble. Sometimes, the yt... | https://en.wikipedia.org/wiki?curid=145440 |
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