Mineralization pyrophosphate removal

Humic acids are alkaH-extractable materials and total humic acid content is a term that refers to the humic acid content of coal that has had its carboxylate cations removed with sodium pyrophosphate. Values for some typical AustraHan brown coals range from 24—92% (13). Treatment of lignitic coals with mineral acid to release the alkaH and alkaline cations may dissolve up to 20% of the coal. The naturally moist coals are slightly acidic and have a pH of 3.5—6.5. 

Elastomeric Fibers. Elastomeric fibers are polyurethanes combiaed with other nonelastic fibers to produce fabrics with controlled elasticity (see Fibers, elastomeric). Processing chemicals must be carefully selected to protect all fibers present ia the blend. Prior to scouriag, the fabrics are normally steamed to relax uneven tensions placed on the fibers duriag weaving. Scouriag, which is used to remove lubricants and siting, is normally conducted with aqueous solutions of synthetic detergents and tetrasodium pyrophosphate, with aqueous emulsions of perchloroethylene or with mineral spidts and sodium pyrophosphate. 

Fig.9.8 Removal of pyrophosphate is necessary for precipitation. Pyrophosphate (PPi) inhibits the precipitation of calcium phosphate. In the bone matrix, PC-1 (red) is the major producer of PPi from nucleotide triphosphates (NTPs, thick arrow on left) and ANK is a minor producer by transporting it from the cytosol of osteoblasts. TNAP (green) causes mineralization by its phosphatase activity converting PPi to two molecules of Pi. TNAP also generates Pi directly from NTPs and PPi, but most Pi and most Ca2+ are derived directly from the diet (thick arrow on right) (Slightly modified from Fig. 4 in Hessle L et al. (2002) Tissue-nonspecific alkaline phosphatase and plasma cell membrane glycoprotein-1 are central antagonistic regulators of bone mineralization. Proceedings of the National Academy of Sciences 99 9445-9449. Copyright (2002) National Academy of Sciences, U.S.A)...

Plaque that is not removed from the teeth becomes calcified from minerals in the saliva. The calcified plaque is known as tartar. It is possible to control tartar buildup by using toothpastes containing sodium pyrophosphate (Na P20y), which interferes with the mineral crystallization that causes tartar buildup. Beneath the gum line, tartar is a special problem because its presence makes it easier for plaque to grow, which irritates gum tissue and allows the gum to become diseased. Only a dentist or oral hygienist can remove tartar from beneath the gum line. By keeping teeth free from plaque and from prolonged contact with the acids produced by plaque bacteria, we can preserve the hard, stonelike enamel of the tooth. 

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