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Some of our finest [ about ] Approved Articles Developed Articles (over 800) Share your knowledge. It's a way to achieve immortality. —Often attributed to the Dalai Lama Article of the Week [ about ] Phosphorus is a chemical element with the atomic number Z = 15. Unlike other elements in group VA of the periodic table, phosphorus is never found as a pure element in nature, but only in combination with other elements. It is present in all living organisms in the form of organophosphates and as calcium phosphates such as hydroxyapatite (Ca10(PO4)6(OH)2) and fluoroapatite (Ca10(PO4)6F2), substances found in teeth and bones. Many cell signaling cascades in living organisms operate by a series of phosphorylation events in which a phosphate group (PO4)2− is either added to a protein by a kinase or removed from a protein by a phosphorylase. Both red phosphorus and tetraphosphorus trisulfide are used in common matches because they are easily ignited by heat. However, the agricultural industry is the largest user of phosphorus in the form of fertilizers. The radioactive isotope 32P is used to radiolabel compounds for scientific studies. Phosphorus and arsenic share many chemical properties. Production of elemental phosphorus Calcium phosphate (phosphate rock), mostly mined in Florida and North Africa, can be heated to 1200-1500 Celsius with sand, which is mostly SiO2, and coke (impure carbon) to produce vaporized tetraphosphorus, P4, (mp. 44.2 C) which is subsequently condensed into a white power under water to prevent oxidation. Even under water, white phosphorus is slowly converted to the more stable red phosphorus allotrope (mp. 597C). Both the white and red allotropes of phosphorus are insoluble in water.[more...] New Draft of the Week [ about ] Dazed and Confused is a song rewritten and arranged by British rock group Led Zeppelin, based on an original composition by Jake Holmes, also titled "Dazed and Confused". Led Zeppelin's heavier and electric Dazed and Confused was considered so significantly different from the Holmes acoustic version that the American Society of Composers, Authors and Publishers (ASCAP) assigned the unique serial registration of 340128276 to its copyright, lodged by the newly created music publisher Superhype Music in 1968. Led Zeppelin's Dazed and Confused has since been widely covered and was an early performance highlight for the group. [more...]