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19-477: The Harrat Kishb plateau contains many volcanic cones. It is 250 m (820 ft) deep and two kilometres ( 1 + 1 ⁄ 4 miles) in diameter. The bottom of the crater is covered with white sodium phosphate crystals. While it was thought for some time that the crater was formed by a meteorite , as its appearance resembles that of the Barringer Crater , with its circular form and high sides, it

38-441: A mixture of doubly and singly protonated forms. Disodium pyrophosphate is prepared by thermal condensation of sodium dihydrogen phosphate or by partial deprotonation of pyrophosphoric acid. Pyrophosphates are generally white or colorless. The alkali metal salts are water-soluble. They are good complexing agents for metal ions (such as calcium and many transition metals) and have many uses in industrial chemistry. Pyrophosphate

57-482: A natural inhibitor of hydroxyapatite formation in extracellular fluid (ECF). Cells may channel intracellular PP i into ECF. ANK is a nonenzymatic plasma-membrane PP i channel that supports extracellular PP i levels. Defective function of the membrane PP i channel ANK is associated with low extracellular PP i and elevated intracellular PP i . Ectonucleotide pyrophosphatase/phosphodiesterase (ENPP) may function to raise extracellular PP i . From

76-696: A risk of kidney injury under the form of phosphate nephropathy . There are several oral phosphate formulations which are prepared extemporaneously. Oral phosphate prep drugs have been withdrawn in the United States, although evidence of causality is equivocal. Since safe and effective replacements for phosphate purgatives are available, several medical authorities have recommended general disuse of oral phosphates. Three families of sodium monophosphates are common, those derived from orthophosphate ( PO 3− 4 ), hydrogen phosphate ( HPO 2− 4 ), and dihydrogenphosphate ( H 2 PO − 4 ). Some of

95-448: Is a cyclic polyphosphate with the formula Na 6 [(PO 3 ) 6 ] . Crystalline high molecular weight polyphosphates include Kurrol's salt and Maddrell's salt (CAS#10361-03-2). These species have the formula [NaPO 3 ] n [NaPO 3 (OH)] 2 where n can be as great as 2000, and it is a white powder practically insoluble in water. In terms of their structures, these polymers consist of PO − 3 units, with

114-463: Is also sometimes referred to as a phosphoanhydride bond, a naming convention which emphasizes the loss of water that occurs when two phosphates form a new P−O−P bond, and which mirrors the nomenclature for anhydrides of carboxylic acids . Pyrophosphates are found in ATP and other nucleotide triphosphates, which are important in biochemistry. The term pyrophosphate is also the name of esters formed by

133-404: Is now commonly accepted by geologists that the crater is a maar crater, and was formed by volcanic activity in the form of an underground phreatic eruption – a massive steam explosion generated by molten basaltic magma coming into contact with subterranean water. The remains of date palm plantations can be found halfway down the side of the crater, but they are disused. There are springs near

152-442: Is some vegetation located. It takes a person 45–60 minutes to go to the bottom of the crater. This crater is very slippery and it is hard for people to come up to the surface. To climb back up takes approx 60–90 minutes. There is some mobile phone signal within the crater, and the site receives very few visitors, even over weekends. As of April 2017, there has been upgrades to the park. A stone wall has been erected about 1/4 to 1/3 of

171-413: Is the first member of an entire series of polyphosphates . The anion P 2 O 4− 7 is abbreviated PP i , standing for i norganic p yro p hosphate . It is formed by the hydrolysis of ATP into AMP in cells . For example, when a nucleotide is incorporated into a growing DNA or RNA strand by a polymerase , pyrophosphate (PP i ) is released. Pyrophosphorolysis is the reverse of

190-473: The polymerization reaction in which pyrophosphate reacts with the 3′-nucleosidemonophosphate ( NMP or dNMP), which is removed from the oligonucleotide to release the corresponding triphosphate ( dNTP from DNA, or NTP from RNA). The pyrophosphate anion has the structure P 2 O 4− 7 , and is an acid anhydride of phosphate . It is unstable in aqueous solution and hydrolyzes into inorganic phosphate: or in biologists' shorthand notation: In

209-619: The absence of enzymic catalysis, hydrolysis reactions of simple polyphosphates such as pyrophosphate, linear triphosphate, ADP , and ATP normally proceed extremely slowly in all but highly acidic media. (The reverse of this reaction is a method of preparing pyrophosphates by heating phosphates.) This hydrolysis to inorganic phosphate effectively renders the cleavage of ATP to AMP and PP i irreversible , and biochemical reactions coupled to this hydrolysis are irreversible as well. PP i occurs in synovial fluid , blood plasma , and urine at levels sufficient to block calcification and may be

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228-772: The anhydrous forms. Sodium phosphates have many applications in food and for water treatment. For example, sodium phosphates are often used as emulsifiers (as in processed cheese ), thickening agents , and leavening agents for baked goods. They are also used to control pH of processed foods. They are also used in medicine for constipation and to prepare the bowel for medical procedures. They are also used in detergents for softening water and as an efficient anti- rust solution. Sodium phosphates are popular in commerce in part because they are inexpensive and because they are nontoxic at normal levels of consumption. However, oral sodium phosphates when taken at high doses for bowel preparation for colonoscopy may in some individuals carry

247-461: The best known salts are shown in the following table. In addition to these phosphates, sodium forms a number of useful salts with pyrophosphates (also called diphosphates), triphosphates and high polymers. Of these salts, those of the diphosphates are particularly common commercially. Beyond the diphosphates, sodium salts are known triphosphates, e.g. sodium triphosphate and tetraphosphates. The cyclic polyphosphates, called metaphosphates, include

266-551: The chains are terminated by protonated phosphates. Pyrophosphate In chemistry , pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a P−O−P linkage. A number of pyrophosphate salts exist, such as disodium pyrophosphate ( Na 2 H 2 P 2 O 7 ) and tetrasodium pyrophosphate ( Na 4 P 2 O 7 ), among others. Often pyrophosphates are called diphosphates . The parent pyrophosphates are derived from partial or complete neutralization of pyrophosphoric acid . The pyrophosphate bond

285-503: The condensation of a phosphorylated biological compound with inorganic phosphate , as for dimethylallyl pyrophosphate . This bond is also referred to as a high-energy phosphate bond. Pyrophosphoric acid is a tetraprotic acid, with four distinct p K a 's: The pKa's occur in two distinct ranges because deprotonations occur on separate phosphate groups. For comparison with the p K a 's for phosphoric acid are 2.14, 7.20, and 12.37. At physiological pH 's, pyrophosphate exists as

304-643: The crater rim from the northwest to southwest. There is a mosque at the end of the entrance road. There are also upgraded picnic shelters around the rim. 22°54′0″N 41°8′20″E  /  22.90000°N 41.13889°E  / 22.90000; 41.13889 Other notes: Sodium phosphate A sodium phosphate is a generic variety of salts of sodium ( Na ) and phosphate ( PO 3− 4 ). Phosphate also forms families or condensed anions including di-, tri-, tetra-, and polyphosphates . Most of these salts are known in both anhydrous (water-free) and hydrated forms. The hydrates are more common than

323-475: The plantations. It is easy to climb down from the rim to the bottom of the crater there from the north side on a prepared path, although most of the circumference has steep unclimbable cliffs. At the top of the path is a stone hut which contains rubbish and debris, and some suitable places for camping, although there are better places to camp to the south (see below). In the north of the Wahbah Crater, there

342-399: The standpoint of high energy phosphate accounting, the hydrolysis of ATP to AMP and PP i requires two high-energy phosphates, as to reconstitute AMP into ATP requires two phosphorylation reactions. The plasma concentration of inorganic pyrophosphate has a reference range of 0.58–3.78  μM (95% prediction interval). Isopentenyl pyrophosphate converts to geranyl pyrophosphate ,

361-462: The trimer sodium trimetaphosphate and the tetramer, Na 3 P 3 O 9 and Na 4 P 4 O 12 , respectively. Polymeric sodium phosphates are formed upon heating mixtures of NaH 2 PO 4 and Na 2 HPO 4 , which induces a condensation reaction . The specific polyphosphate generated depends on the details of the heating and annealing. One derivative is the glassy (i.e., amorphous) Graham's salt ( sodium hexametaphosphate ). It

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