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13,300 | The Republic of Korea Air Force purchased its first batch of secondhand USAF F-4D Phantoms in 1968 under the "Peace Spectator" program. The F-4Ds continued to be delivered until 1988. The "Peace Pheasant II" program also provided new-built and former USAF F-4Es. | https://en.wikipedia.org/wiki?curid=11759 |
13,301 | The Spanish Air Force acquired its first batch of ex-USAF F-4C Phantoms in 1971 under the "Peace Alfa" program. Designated C.12, the aircraft were retired in 1989. At the same time, the air arm received a number of ex-USAF RF-4Cs, designated CR.12. In 1995–1996, these aircraft received extensive avionics upgrades. Spai... | https://en.wikipedia.org/wiki?curid=11759 |
13,302 | The Turkish Air Force (TAF) received 40 F-4Es in 1974, with a further 32 F-4Es and 8 RF-4Es in 1977–78 under the "Peace Diamond III" program, followed by 40 ex-USAF aircraft in "Peace Diamond IV" in 1987, and a further 40 ex-U.S. Air National Guard Aircraft in 1991. A further 32 RF-4Es were transferred to Turkey after ... | https://en.wikipedia.org/wiki?curid=11759 |
13,303 | On 24 February 2015, two RF-4Es crashed in the Malatya region in the southeast of Turkey, under yet unknown circumstances, killing both crew of two each. On 5 March 2015, an F-4E-2020 crashed in central Anatolia killing both crew. After the recent accidents, the TAF withdrew RF-4Es from active service. Turkey was repor... | https://en.wikipedia.org/wiki?curid=11759 |
13,304 | The United Kingdom bought versions based on the U.S. Navy's F-4J for use with the Royal Air Force and the Royal Navy's Fleet Air Arm. The UK was the only country outside the United States to operate the Phantom at sea, with them operating from . The main differences were the use of the British Rolls-Royce Spey engines ... | https://en.wikipedia.org/wiki?curid=11759 |
13,305 | Initially, the FGR.2 was used in the ground attack and reconnaissance role, primarily with RAF Germany, while 43 Squadron was formed in the air defense role using the FG.1s that had been intended for the Fleet Air Arm for use aboard . The superiority of the Phantom over the English Electric Lightning in terms of both r... | https://en.wikipedia.org/wiki?curid=11759 |
13,306 | In 1982, during the Falklands War, three Phantom FGR2s of No. 29 Squadron were on active Quick Reaction Alert duty on Ascension Island to protect the base from air attack. After the Falklands War, 15 upgraded ex-USN F-4Js, known as the F-4J(UK) entered RAF service to compensate for one interceptor squadron redeployed t... | https://en.wikipedia.org/wiki?curid=11759 |
13,307 | Around 15 RAF squadrons received various marks of Phantom, many of them based in Germany. The first to be equipped was No. 228 Operational Conversion Unit at RAF Coningsby in August 1968. One noteworthy operator was No. 43 Squadron where Phantom FG1s remained the squadron equipment for 20 years, arriving in September 1... | https://en.wikipedia.org/wiki?curid=11759 |
13,308 | The interceptor Phantoms were replaced by the Panavia Tornado F3 from the late 1980s onwards, and the last combat British Phantoms were retired in October 1992 when No. 74(F) Squadron was disbanded. Phantom FG.1 "XT597" was the last British Phantom to be retired on 28 January 1994, it was used as a test jet by the Aero... | https://en.wikipedia.org/wiki?curid=11759 |
13,309 | Sandia National Laboratories expended an F-4 mounted on a "rocket sled" in a crash test to record the results of an aircraft impacting a reinforced concrete structure, such as a nuclear power plant. | https://en.wikipedia.org/wiki?curid=11759 |
13,310 | One aircraft, an F-4D (civilian registration NX749CF), is operated by the Massachusetts-based non-profit organization Collings Foundation as a "living history" exhibit. Funds to maintain and operate the aircraft, which is based in Houston, Texas, are raised through donations/sponsorships from public and commercial part... | https://en.wikipedia.org/wiki?curid=11759 |
13,311 | After finding the Lockheed F-104 Starfighter inadequate, NASA used the F-4 to photograph and film Titan II missiles after launch from Cape Canaveral during the 1960s. Retired U.S. Air Force colonel Jack Petry described how he put his F-4 into a Mach 1.2 dive synchronized to the launch countdown, then "walked the (rocke... | https://en.wikipedia.org/wiki?curid=11759 |
13,312 | NASA's Dryden Flight Research Center acquired an F-4A on 3 December 1965. It made 55 flights in support of short programs, chase on X-15 missions and lifting body flights. The F-4 also supported a biomedical monitoring program involving 1,000 flights by NASA Flight Research Center aerospace research pilots and students... | https://en.wikipedia.org/wiki?curid=11759 |
13,313 | The Phantom gathered a number of nicknames during its career. Some of these names included "Snoopy", "Rhino", "Double Ugly", "Old Smokey", the "Flying Anvil", "Flying Footlocker", "Flying Brick", "Lead Sled", the "Big Iron Sled", and the "St. Louis Slugger". In recognition of its record of downing large numbers of Sovi... | https://en.wikipedia.org/wiki?curid=11759 |
13,314 | Imitating the spelling of the aircraft's name, McDonnell issued a series of patches. Pilots became "Phantom Phlyers", backseaters became "Phantom Pherrets", fans of the F-4 "Phantom Phanatics", and call it the "Phabulous Phantom". Ground crewmen who worked on the aircraft are known as "Phantom Phixers". | https://en.wikipedia.org/wiki?curid=11759 |
13,315 | Several active websites are devoted to sharing information on the F-4, and the aircraft is grudgingly admired as brutally effective by those who have flown it. Colonel (Ret.) Chuck DeBellevue reminisced, "The F-4 Phantom was the last plane that looked like it was made to kill somebody. It was a beast. It could go throu... | https://en.wikipedia.org/wiki?curid=11759 |
13,316 | The aircraft's emblem is a whimsical cartoon ghost called "The Spook", which was created by McDonnell Douglas technical artist, Anthony "Tony" Wong, for shoulder patches. The name "Spook" was coined by the crews of either the 12th Tactical Fighter Wing or the 4453rd Combat Crew Training Wing at MacDill AFB. The figure ... | https://en.wikipedia.org/wiki?curid=11759 |
13,317 | As a result of its extensive number of operators and large number of aircraft produced, there are many F-4 Phantom II of numerous variants on display worldwide. | https://en.wikipedia.org/wiki?curid=11759 |
13,318 | Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the u... | https://en.wikipedia.org/wiki?curid=13255 |
13,319 | In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 years later during the recombination epoch, when the plasma had cooled enough for electrons to remain bound... | https://en.wikipedia.org/wiki?curid=13255 |
13,320 | Hydrogen is nonmetallic (except it becomes metallic at extremely high pressures) and readily forms a single covalent bond with most nonmetallic elements, forming compounds such as water and nearly all organic compounds. Hydrogen plays a particularly important role in acid–base reactions because these reactions usually ... | https://en.wikipedia.org/wiki?curid=13255 |
13,321 | Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. In 1766–1781, Henry Cavendish was the first to recognize that hydrogen gas was a discrete substance, and that it produces water when burned, the property for which it was later named: in Greek, hydrogen means "wat... | https://en.wikipedia.org/wiki?curid=13255 |
13,322 | Industrial production is mainly from steam reforming of natural gas, oil reforming, or coal gasification. A small percentage is also produced using more energy-intensive methods such as the electrolysis of water. Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing (e... | https://en.wikipedia.org/wiki?curid=13255 |
13,323 | Hydrogen gas forms explosive mixtures with air in concentrations from 4–74% and with chlorine at 5–95%. The explosive reactions may be triggered by spark, heat, or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is . | https://en.wikipedia.org/wiki?curid=13255 |
13,324 | Pure hydrogen-oxygen flames emit ultraviolet light and with high oxygen mix are nearly invisible to the naked eye, as illustrated by the faint plume of the Space Shuttle Main Engine, compared to the highly visible plume of a Space Shuttle Solid Rocket Booster, which uses an ammonium perchlorate composite. The detection... | https://en.wikipedia.org/wiki?curid=13255 |
13,325 | is unreactive compared to diatomic elements such as halogens or oxygen. The thermodynamic basis of this low reactivity is the very strong H–H bond, with a bond dissociation energy of 435.7 kJ/mol. The kinetic basis of the low reactivity is the nonpolar nature of and its weak polarizability. It spontaneously reacts with... | https://en.wikipedia.org/wiki?curid=13255 |
13,326 | The ground state energy level of the electron in a hydrogen atom is −13.6 eV, which is equivalent to an ultraviolet photon of roughly 91 nm wavelength. | https://en.wikipedia.org/wiki?curid=13255 |
13,327 | The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom, which conceptualizes the electron as "orbiting" the proton in analogy to the Earth's orbit of the Sun. However, the atomic electron and proton are held together by electromagnetic force, while planets and celestial objec... | https://en.wikipedia.org/wiki?curid=13255 |
13,328 | A more accurate description of the hydrogen atom comes from a purely quantum mechanical treatment that uses the Schrödinger equation, Dirac equation or Feynman path integral formulation to calculate the probability density of the electron around the proton. The most complicated treatments allow for the small effects of... | https://en.wikipedia.org/wiki?curid=13255 |
13,329 | Molecular exists as two spin isomers, i.e. compounds that differ only in the spin states of their nuclei. In the orthohydrogen form, the spins of the two nuclei are parallel, forming a spin triplet state having a total molecular spin formula_1; in the parahydrogen form the spins are antiparallel and form a spin singlet... | https://en.wikipedia.org/wiki?curid=13255 |
13,330 | The ortho-to-para ratio in is an important consideration in the liquefaction and storage of liquid hydrogen: the conversion from ortho to para is exothermic and produces enough heat to evaporate a most of the liquid if not converted first to parahydrogen during the cooling process. Catalysts for the ortho-para intercon... | https://en.wikipedia.org/wiki?curid=13255 |
13,331 | While is not very reactive under standard conditions, it does form compounds with most elements. Hydrogen can form compounds with elements that are more electronegative, such as halogens (F, Cl, Br, I), or oxygen; in these compounds hydrogen takes on a partial positive charge. When bonded to a more electronegative elem... | https://en.wikipedia.org/wiki?curid=13255 |
13,332 | Hydrogen forms a vast array of compounds with carbon called the hydrocarbons, and an even vaster array with heteroatoms that, because of their general association with living things, are called organic compounds. The study of their properties is known as organic chemistry and their study in the context of living organi... | https://en.wikipedia.org/wiki?curid=13255 |
13,333 | Hydrogen is highly soluble in many rare earth and transition metals and is soluble in both nanocrystalline and amorphous metals. Hydrogen solubility in metals is influenced by local distortions or impurities in the crystal lattice. These properties may be useful when hydrogen is purified by passage through hot palladiu... | https://en.wikipedia.org/wiki?curid=13255 |
13,334 | Compounds of hydrogen are often called hydrides, a term that is used fairly loosely. The term "hydride" suggests that the H atom has acquired a negative or anionic character, denoted , and is used when hydrogen forms a compound with a more electropositive element. The existence of the hydride anion, suggested by Gilber... | https://en.wikipedia.org/wiki?curid=13255 |
13,335 | Although hydrides can be formed with almost all main-group elements, the number and combination of possible compounds varies widely; for example, more than 100 binary borane hydrides are known, but only one binary aluminium hydride. Binary indium hydride has not yet been identified, although larger complexes exist. | https://en.wikipedia.org/wiki?curid=13255 |
13,336 | In inorganic chemistry, hydrides can also serve as bridging ligands that link two metal centers in a coordination complex. This function is particularly common in group 13 elements, especially in boranes (boron hydrides) and aluminium complexes, as well as in clustered carboranes. | https://en.wikipedia.org/wiki?curid=13255 |
13,337 | Oxidation of hydrogen removes its electron and gives , which contains no electrons and a nucleus which is usually composed of one proton. That is why is often called a proton. This species is central to discussion of acids. Under the Brønsted–Lowry acid–base theory, acids are proton donors, while bases are proton accep... | https://en.wikipedia.org/wiki?curid=13255 |
13,338 | A bare proton, , cannot exist in solution or in ionic crystals because of its unstoppable attraction to other atoms or molecules with electrons. Except at the high temperatures associated with plasmas, such protons cannot be removed from the electron clouds of atoms and molecules, and will remain attached to them. Howe... | https://en.wikipedia.org/wiki?curid=13255 |
13,339 | To avoid the implication of the naked "solvated proton" in solution, acidic aqueous solutions are sometimes considered to contain a less unlikely fictitious species, termed the "hydronium ion" (). However, even in this case, such solvated hydrogen cations are more realistically conceived as being organized into cluster... | https://en.wikipedia.org/wiki?curid=13255 |
13,340 | Although exotic on Earth, one of the most common ions in the universe is the ion, known as protonated molecular hydrogen or the trihydrogen cation. | https://en.wikipedia.org/wiki?curid=13255 |
13,341 | Hydrogen has three naturally occurring isotopes, denoted , and . Other, highly unstable nuclei ( to ) have been synthesized in the laboratory but not observed in nature. | https://en.wikipedia.org/wiki?curid=13255 |
13,342 | Unique among the elements, distinct names are assigned to its isotopes in common use today. During the early study of radioactivity, various heavy radioactive isotopes were given their own names, but such names are no longer used, except for deuterium and tritium. The symbols D and T (instead of and ) are sometimes use... | https://en.wikipedia.org/wiki?curid=13255 |
13,343 | The exotic atom muonium (symbol Mu), composed of an antimuon and an electron, can also be considered a light radioisotope of hydrogen. Because muons decay with lifetime , muonium is too unstable to exhibit observable chemistry. Nevertheless, muonium compounds are important test cases for quantum simulation, due to the ... | https://en.wikipedia.org/wiki?curid=13255 |
13,344 | In 1671, Robert Boyle discovered and described the reaction between iron filings and dilute acids, which results in the production of hydrogen gas. | https://en.wikipedia.org/wiki?curid=13255 |
13,345 | In 1766, Henry Cavendish was the first to recognize hydrogen gas as a discrete substance, by naming the gas from a metal-acid reaction "inflammable air". He speculated that "inflammable air" was in fact identical to the hypothetical substance called "phlogiston" and further finding in 1781 that the gas produces water w... | https://en.wikipedia.org/wiki?curid=13255 |
13,346 | Lavoisier produced hydrogen for his experiments on mass conservation by reacting a flux of steam with metallic iron through an incandescent iron tube heated in a fire. Anaerobic oxidation of iron by the protons of water at high temperature can be schematically represented by the set of following reactions: | https://en.wikipedia.org/wiki?curid=13255 |
13,347 | Many metals such as zirconium undergo a similar reaction with water leading to the production of hydrogen. | https://en.wikipedia.org/wiki?curid=13255 |
13,348 | Hydrogen was liquefied for the first time by James Dewar in 1898 by using regenerative cooling and his invention, the vacuum flask. He produced solid hydrogen the next year. Deuterium was discovered in December 1931 by Harold Urey, and tritium was prepared in 1934 by Ernest Rutherford, Mark Oliphant, and Paul Harteck. ... | https://en.wikipedia.org/wiki?curid=13255 |
13,349 | The first hydrogen-filled balloon was invented by Jacques Charles in 1783. Hydrogen provided the lift for the first reliable form of air-travel following the 1852 invention of the first hydrogen-lifted airship by Henri Giffard. German count Ferdinand von Zeppelin promoted the idea of rigid airships lifted by hydrogen t... | https://en.wikipedia.org/wiki?curid=13255 |
13,350 | The first non-stop transatlantic crossing was made by the British airship "R34" in 1919. Regular passenger service resumed in the 1920s and the discovery of helium reserves in the United States promised increased safety, but the U.S. government refused to sell the gas for this purpose. Therefore, was used in the "Hinde... | https://en.wikipedia.org/wiki?curid=13255 |
13,351 | In the same year, the first hydrogen-cooled turbogenerator went into service with gaseous hydrogen as a coolant in the rotor and the stator in 1937 at Dayton, Ohio, by the Dayton Power & Light Co.; because of the thermal conductivity and very low viscosity of hydrogen gas, thus lower drag than air, this is the most com... | https://en.wikipedia.org/wiki?curid=13255 |
13,352 | The nickel hydrogen battery was used for the first time in 1977 aboard the U.S. Navy's Navigation technology satellite-2 (NTS-2). For example, the ISS, Mars Odyssey and the Mars Global Surveyor are equipped with nickel-hydrogen batteries. In the dark part of its orbit, the Hubble Space Telescope is also powered by nick... | https://en.wikipedia.org/wiki?curid=13255 |
13,353 | Because of its simple atomic structure, consisting only of a proton and an electron, the hydrogen atom, together with the spectrum of light produced from it or absorbed by it, has been central to the development of the theory of atomic structure. Furthermore, study of the corresponding simplicity of the hydrogen molecu... | https://en.wikipedia.org/wiki?curid=13255 |
13,354 | One of the first quantum effects to be explicitly noticed (but not understood at the time) was a Maxwell observation involving hydrogen, half a century before full quantum mechanical theory arrived. Maxwell observed that the specific heat capacity of unaccountably departs from that of a diatomic gas below room temperat... | https://en.wikipedia.org/wiki?curid=13255 |
13,355 | Antihydrogen () is the antimatter counterpart to hydrogen. It consists of an antiproton with a positron. Antihydrogen is the only type of antimatter atom to have been produced . | https://en.wikipedia.org/wiki?curid=13255 |
13,356 | Hydrogen, as atomic H, is the most abundant chemical element in the universe, making up 75 percent of normal matter by mass and more than 90 percent by number of atoms. (Most of the mass of the universe, however, is not in the form of chemical-element type matter, but rather is postulated to occur as yet-undetected for... | https://en.wikipedia.org/wiki?curid=13255 |
13,357 | Throughout the universe, hydrogen is mostly found in the atomic and plasma states, with properties quite distinct from those of molecular hydrogen. As a plasma, hydrogen's electron and proton are not bound together, resulting in very high electrical conductivity and high emissivity (producing the light from the Sun and... | https://en.wikipedia.org/wiki?curid=13255 |
13,358 | Hydrogen is found in the neutral atomic state in the interstellar medium because the atoms seldom collide and combine. They are the source of the 21-cm hydrogen line at 1420 MHz that is detected in order to probe primordial hydrogen. The large amount of neutral hydrogen found in the damped Lyman-alpha systems is though... | https://en.wikipedia.org/wiki?curid=13255 |
13,359 | Under ordinary conditions on Earth, elemental hydrogen exists as the diatomic gas, . Hydrogen gas is very rare in the Earth's atmosphere (1 ppm by volume) because of its light weight, which enables it to escape from the atmosphere more rapidly than heavier gases. However, hydrogen is the third most abundant element on ... | https://en.wikipedia.org/wiki?curid=13255 |
13,360 | A molecular form called protonated molecular hydrogen () is found in the interstellar medium, where it is generated by ionization of molecular hydrogen from cosmic rays. This ion has also been observed in the upper atmosphere of the planet Jupiter. The ion is relatively stable in the environment of outer space due to t... | https://en.wikipedia.org/wiki?curid=13255 |
13,361 | is produced in chemistry and biology laboratories, often as a by-product of other reactions; in industry for the hydrogenation of unsaturated substrates; and in nature as a means of expelling reducing equivalents in biochemical reactions. | https://en.wikipedia.org/wiki?curid=13255 |
13,362 | The electrolysis of water is a simple method of producing hydrogen. A current is run through the water, and gaseous oxygen forms at the anode while gaseous hydrogen forms at the cathode. Typically the cathode is made from platinum or another inert metal when producing hydrogen for storage. If, however, the gas is to be... | https://en.wikipedia.org/wiki?curid=13255 |
13,363 | Hydrogen production using natural gas methane pyrolysis is a one-step process that produces no greenhouse gases. Developing volume production using this method is the key to enabling faster carbon reduction by using hydrogen in industrial processes, fuel cell electric heavy truck transportation, and in gas turbine elec... | https://en.wikipedia.org/wiki?curid=13255 |
13,364 | The industrial quality solid carbon may be sold as manufacturing feedstock or permanently landfilled; it is not released into the atmosphere and does not cause ground water pollution in landfill. Methane pyrolysis is in development and considered suitable for commercial bulk hydrogen production. Volume production is be... | https://en.wikipedia.org/wiki?curid=13255 |
13,365 | Hydrogen is often produced by reacting water with methane and carbon monoxide, which causes the removal of hydrogen from hydrocarbons at very high temperatures, with 48% of hydrogen production coming from steam reforming. The water vapor is then reacted with the carbon monoxide produced by steam reforming to oxidize it... | https://en.wikipedia.org/wiki?curid=13255 |
13,366 | At high temperatures (1000–1400 K, 700–1100 °C or 1300–2000 °F), steam (water vapor) reacts with methane to yield carbon monoxide and . | https://en.wikipedia.org/wiki?curid=13255 |
13,367 | This reaction is favored at low pressures but is nonetheless conducted at high pressures (2.0 MPa, 20 atm or 600 inHg). This is because high-pressure is the most marketable product, and pressure swing adsorption (PSA) purification systems work better at higher pressures. The product mixture is known as "synthesis gas" ... | https://en.wikipedia.org/wiki?curid=13255 |
13,368 | Consequently, steam reforming typically employs an excess of . Additional hydrogen can be recovered from the steam by use of carbon monoxide through the water gas shift reaction, especially with an iron oxide catalyst. This reaction is also a common industrial source of carbon dioxide: | https://en.wikipedia.org/wiki?curid=13255 |
13,369 | Hydrogen is sometimes produced and consumed in the same industrial process, without being separated. In the Haber process for the production of ammonia, hydrogen is generated from natural gas. Electrolysis of brine to yield chlorine also produces hydrogen as a co-product. | https://en.wikipedia.org/wiki?curid=13255 |
13,370 | Olefin production units may produce substantial quantities of byproduct hydrogen particularly from cracking light feedstocks like ethane or propane. | https://en.wikipedia.org/wiki?curid=13255 |
13,371 | Many metals react with water to produce , but the rate of hydrogen evolution depends on the metal, the pH, and the presence alloying agents. Most commonly, hydrogen evolution is induced by acids. The alkali and alkaline earth metals, aluminium, zinc, manganese, and iron react readily with aqueous acids. This reaction i... | https://en.wikipedia.org/wiki?curid=13255 |
13,372 | In the absence of acid, the evolution of is slower. Because iron is widely used structural material, its anaerobic corrosion is of technological significance: | https://en.wikipedia.org/wiki?curid=13255 |
13,373 | Many metals, such as aluminium, are slow to react with water because they form passivated coatings of oxides. An alloy of aluminium and gallium, however, does react with water. At high pH, aluminium can produce : | https://en.wikipedia.org/wiki?curid=13255 |
13,374 | Some metal-containing compounds react with acids to evolve . Under anaerobic conditions, ferrous hydroxide () can be oxidized by the protons of water to form magnetite and . This process is described by the Schikorr reaction: | https://en.wikipedia.org/wiki?curid=13255 |
13,375 | This process occurs during the anaerobic corrosion of iron and steel in oxygen-free groundwater and in reducing soils below the water table. | https://en.wikipedia.org/wiki?curid=13255 |
13,376 | More than 200 thermochemical cycles can be used for water splitting. Many of these cycles such as the iron oxide cycle, cerium(IV) oxide–cerium(III) oxide cycle, zinc zinc-oxide cycle, sulfur-iodine cycle, copper-chlorine cycle and hybrid sulfur cycle have been evaluated for their commercial potential to produce hydrog... | https://en.wikipedia.org/wiki?curid=13255 |
13,377 | In deep geological conditions prevailing far away from the Earth's atmosphere, hydrogen () is produced during the process of serpentinization. In this process, water protons () are reduced by ferrous () ions provided by fayalite (). The reaction forms magnetite (), quartz (), and hydrogen (): | https://en.wikipedia.org/wiki?curid=13255 |
13,378 | This reaction closely resembles the Schikorr reaction observed in anaerobic oxidation of ferrous hydroxide in contact with water. | https://en.wikipedia.org/wiki?curid=13255 |
13,379 | Large quantities of are used in the "upgrading" of fossil fuels. Key consumers of include hydrodealkylation, hydrodesulfurization, and hydrocracking. Many of these reactions can be classified as hydrogenolysis, i.e., the cleavage of bonds to carbon. Illustrative is the separation of sulfur from liquid fossil fuels: | https://en.wikipedia.org/wiki?curid=13255 |
13,380 | Hydrogenation, the addition of to various substrates is conducted on a large scale. The hydrogenation of to produce ammonia by the Haber–Bosch process consumes a few percent of the energy budget in the entire industry. The resulting ammonia is used to supply the majority of the protein consumed by humans. Hydrogenation... | https://en.wikipedia.org/wiki?curid=13255 |
13,381 | Hydrogen is commonly used in power stations as a coolant in generators due to a number of favorable properties that are a direct result of its light diatomic molecules. These include low density, low viscosity, and the highest specific heat and thermal conductivity of all gases. | https://en.wikipedia.org/wiki?curid=13255 |
13,382 | Elemental hydrogen has been widely discussed in the context of energy, as a possible future carrier of energy on an economy-wide scale. Hydrogen is a <nowiki>"carrier"</nowiki> of energy rather than an energy resource, because there is no naturally occurring source of hydrogen in useful quantities. | https://en.wikipedia.org/wiki?curid=13255 |
13,383 | Hydrogen can be burned to produce heat or combined with oxygen in fuel cells to generate electricity directly, with water being the only emissions at the point of usage. The overall lifecycle emissions of hydrogen depend on how it is produced. Nearly all of the world's current supply of hydrogen is created from fossil ... | https://en.wikipedia.org/wiki?curid=13255 |
13,384 | Electricity can be used to split water molecules, producing sustainable hydrogen provided the electricity was generated sustainably. However, this electrolysis process is currently more expensive than creating hydrogen from methane and the efficiency of energy conversion is inherently low. Hydrogen can be produced when... | https://en.wikipedia.org/wiki?curid=13255 |
13,385 | Innovation in hydrogen electrolysers could make large-scale production of hydrogen from electricity more cost-competitive. There is potential for hydrogen to play a significant role in decarbonising energy systems because in certain sectors, replacing fossil fuels with direct use of electricity would be very difficult.... | https://en.wikipedia.org/wiki?curid=13255 |
13,386 | Hydrogen is employed to saturate broken ("dangling") bonds of amorphous silicon and amorphous carbon that helps stabilizing material properties. It is also a potential electron donor in various oxide materials, including ZnO, , CdO, MgO, , , , , , , , , , , , and . | https://en.wikipedia.org/wiki?curid=13255 |
13,387 | Liquid hydrogen and liquid oxygen together serve as cryogenic fuel in liquid-propellant rockets, as in the Space Shuttle main engines. | https://en.wikipedia.org/wiki?curid=13255 |
13,388 | is a product of some types of anaerobic metabolism and is produced by several microorganisms, usually via reactions catalyzed by iron- or nickel-containing enzymes called hydrogenases. These enzymes catalyze the reversible redox reaction between and its component two protons and two electrons. Creation of hydrogen gas ... | https://en.wikipedia.org/wiki?curid=13255 |
13,389 | Hydrogen gas is produced by some bacteria and algae and is a natural component of flatus, as is methane, itself a hydrogen source of increasing importance. | https://en.wikipedia.org/wiki?curid=13255 |
13,390 | Water splitting, in which water is decomposed into its component protons, electrons, and oxygen, occurs in the light reactions in all photosynthetic organisms. Some such organisms, including the alga "Chlamydomonas reinhardtii" and cyanobacteria, have evolved a second step in the dark reactions in which protons and ele... | https://en.wikipedia.org/wiki?curid=13255 |
13,391 | Hydrogen poses a number of hazards to human safety, from potential detonations and fires when mixed with air to being an asphyxiant in its pure, oxygen-free form. In addition, liquid hydrogen is a cryogen and presents dangers (such as frostbite) associated with very cold liquids. Hydrogen dissolves in many metals and i... | https://en.wikipedia.org/wiki?curid=13255 |
13,392 | Even interpreting the hydrogen data (including safety data) is confounded by a number of phenomena. Many physical and chemical properties of hydrogen depend on the parahydrogen/orthohydrogen ratio (it often takes days or weeks at a given temperature to reach the equilibrium ratio, for which the data is usually given). ... | https://en.wikipedia.org/wiki?curid=13255 |
13,393 | R is a programming language for statistical computing and graphics supported by the R Core Team and the R Foundation for Statistical Computing. Created by statisticians Ross Ihaka and Robert Gentleman, R is used among data miners, bioinformaticians and statisticians for data analysis and developing statistical software... | https://en.wikipedia.org/wiki?curid=376707 |
13,394 | According to user surveys and studies of scholarly literature databases, R is one of the most commonly used programming languages used in data mining. R ranks 12th in the TIOBE index, a measure of programming language popularity, in which the language peaked in 8th place in August 2020. | https://en.wikipedia.org/wiki?curid=376707 |
13,395 | The official R software environment is an open-source free software environment within the GNU package, available under the GNU General Public License. It is written primarily in C, Fortran, and R itself (partially self-hosting). Precompiled executables are provided for various operating systems. R has a command line i... | https://en.wikipedia.org/wiki?curid=376707 |
13,396 | R is an open-source implementation of the S programming language combined with lexical scoping semantics from Scheme, which allow objects to be defined in predetermined blocks rather than the entirety of the code. S was created by Rick Becker, John Chambers, Doug Dunn, Jean McRae, and Judy Schilling at Bell Labs around... | https://en.wikipedia.org/wiki?curid=376707 |
13,397 | In 1991, statisticians Ross Ihaka and Robert Gentleman at the University of Auckland, New Zealand, embarked on an S implementation. It was named partly after the first names of the first two R authors and partly as a play on the name of S. They began publicizing it on the data archive StatLib and the "s-news" mailing l... | https://en.wikipedia.org/wiki?curid=376707 |
13,398 | The Comprehensive R Archive Network (CRAN) was officially announced on 23 April 1997. CRAN stores R's executable files, source code, documentations, as well as packages contributed by users. CRAN originally had 3 mirrors and 12 contributed packages. As of January 2022, it has 101 mirrors and 18,728 contributed packages... | https://en.wikipedia.org/wiki?curid=376707 |
13,399 | The R Core Team was formed in 1997 to further develop the language. , it consists of Chambers, Gentleman, Ihaka, and Mächler, plus statisticians Douglas Bates, Peter Dalgaard, Kurt Hornik, Michael Lawrence, Friedrich Leisch, Uwe Ligges, Thomas Lumley, Sebastian Meyer, Paul Murrell, Martyn Plummer, Brian Ripley, Deepaya... | https://en.wikipedia.org/wiki?curid=376707 |
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