Pentaborane can refer to:
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Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs, with no extinction of its light due to absorption by interstellar dust particles. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared on a magnitude scale. As with all astronomical magnitudes, the absolute magnitude can be specified for different wavelength ranges corresponding to specified filter bands or passbands; for stars a commonly quoted absolute magnitude is the absolute visual magnitude, which uses the visual (V) band of the spectrum. Absolute magnitudes are denoted by a capital M, with a subscript representing the filter band used for measurement, such as MV for absolute magnitude in the V band.
Boron is a chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in the Solar system and in the Earth's crust. Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. These are mined industrially as evaporites, such as borax and kernite. The largest known boron deposits are in Turkey, the largest producer of boron minerals.
A hypergolic propellant combination used in a rocket engine is one whose components spontaneously ignite when they come into contact with each other.
ATPases (EC 3.6.1.3, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, SV40 T-antigen, adenosine 5'-triphosphatase, ATP hydrolase, complex V (mitochondrial electron transport), (Ca2+ + Mg2+)-ATPase, HCO3−-ATPase, adenosine triphosphatase) are a class of enzymes that catalyze the decomposition of ATP into ADP and a free phosphate ion or the inverse reaction. This dephosphorylation reaction releases energy, which the enzyme (in most cases) harnesses to drive other chemical reactions that would not otherwise occur. This process is widely used in all known forms of life.
Boranes is the name given to the class of synthetic hydrides of boron with generic formula BxHy. In the past, borane molecules were often labeled " electron-deficient" because of their multicenter bonding (in which a pair of bonding electrons links more than two atoms, as in 3-center-2-electron bonds); this was done in order to distinguish such molecules from hydrocarbons and other classically bonded compounds. However, this usage is incorrect, as most boranes and related clusters such as carboranes are actually electron-precise, not electron-deficient. For example, the extremely stable icosahedral B12H122- dianion, whose 26 cluster valence electrons exactly fill the 13 bonding molecular orbitals, is in no actual sense deficient in electrons; indeed it is thermodynamically far more stable than benzene.
Decaborane, also called decaborane(14), is the borane with the chemical formula B10H14. This white crystalline compound is one of the principal boron hydride clusters, both as a reference structure and as a precursor to other boron hydrides. It is toxic and volatile, with a foul smelling odor.
Pentaborane(9) is an inorganic compound with the formula B5H9. It is one of the most common boron hydride clusters, although it is a highly reactive compound. Because of its high reactivity toward oxygen, it was once evaluated as rocket or jet fuel. Like many of the smaller boron hydrides, pentaborane is colourless, diamagnetic, and volatile. It is related to pentaborane(11) (B5H11).
Carboranes are electron-delocalized clusters composed of boron, carbon and hydrogen atoms that may also contain other metallic and nonmetallic elements in the cluster framework. Like many of the related boron hydrides, these clusters are polyhedra or fragments of polyhedra, and are similarly classified as closo-, nido-, arachno-, hypho-, etc. based on whether they represent a complete (closo-) polyhedron, or a polyhedron that is missing one (nido-), two (arachno-), three (hypho-), or more vertices. Carboranes are a notable example of heteroboranes.
Hexaborane, also called hexaborane(10) to distinguish it from hexaborane(12) (B6H12), is an inorganic compound with the formula B6H10. It is a colorless liquid that is unstable in air.
SHA-2 is a set of cryptographic hash functions designed by the United States National Security Agency (NSA). They are built using the Merkle–Damgård structure, from a one-way compression function itself built using the Davies–Meyer structure from a (classified) specialized block cipher.
A cyclic number is an integer in which cyclic permutations of the digits are successive multiples of the number. The most widely known is the six-digit number 142857, whose first six integer multiples are
H-E-B is an American privately held supermarket chain based in San Antonio, Texas, with more than 350 stores throughout the U.S. state of Texas, as well as in northeast Mexico. The company also operates Central Market, an upscale organic and fine foods retailer. As of 2017, the company has a total revenue surpassing US$25 billion. H-E-B ranked No. 15 on Forbes' 2014 list of "America's Largest Private Companies". H-E-B was named Retailer of the Year in 2010 by Progressive Grocer. Supermarket News ranked H-E-B No. 13 in the 2008 "Top 75 North American Food Retailers". Based on 2014 revenues, H-E-B is the twentieth largest retailer in the United States. It donates five percent of pre-tax profits to charity.
The Controlled Drugs and Substances Act is Canada's federal drug control statute. Passed in 1996 under Prime Minister Jean Chrétien's government, it repeals the Narcotic Control Act and Parts III and IV of the Food and Drugs Act; and establishes eight Schedules of controlled substances and two Classes of precursors. It provides that "The Governor in Council may, by order, amend any of Schedules I to VIII by adding to them or deleting from them any item or portion of an item, where the Governor in Council deems the amendment to be necessary in the public interest."
In chess, the Dragon Variation is one of the main lines of the Sicilian Defence and begins with the moves:
Triethylborane (TEB), also called triethylboron, is an organoborane (a compound with a B-C bond). It is a colorless pyrophoric liquid. Its chemical formula is (C2H5)3B, abbreviated Et3B. It is soluble in organic solvents tetrahydrofuran and hexane.
Pentaborane(11) is inorganic compound with the chemical formula B5H11. It is an obscure boron hydride cluster, especially relative to the heavily studied pentaborane(9) (B5H9). With two more hydrogen atoms than nido-pentaborane(9), pentaborane(11) is classified as an arachno cluster.
Hexaborane(12) is an inorganic compound with the formula B6H12. It is an obscure member of the boranes. It is a colorless liquid that, like most boron hydrides, is readily hydrolyzed and flammable.
The 2018–19 Bundesliga is the 56th season of the Bundesliga, Germany's premier football competition. It began on 24 August 2018 and will conclude on 18 May 2019. It also marked the first season without Hamburger SV, previously the only team to have played in the top tier of German football in every season since the end of World War I. Bayern Munich are the defending champions.