Phosphate additions

The large amount of fluorine values released from phosphate rock in the manufacture of fertilisers (qv) gives a strong impetus to develop fluorine chemicals production from this source (see Phosphoric acid and the phosphates). Additional incentive comes from the need to control the emission of fluorine-containing gases. Most of the fluorine values are scmbbed out as fluorosiUcic acid, H2SiPg, which has limited useflilness. A procedure to convert fluorosihcic acid to calcium fluoride is available (61). 

Methyl methacrylate is often used in combination with styrene to improve light transmission and uv stabiUty in fiame-retardant glazing appHcations. Phosphate ester (triethyl phosphate) additives are also included to supplement fiame-retardant efficiency benzophenone uv stabilizers are required to prevent yellowing of these uv-sensitive resins. 

Hair Cleaning of sample with acetone/ methanol digestion with acid mixture and heat diammonium phosphate addition as matrix modifier GFAAS 0.16 pg/g 99 Wilhelm et al. 1989... 

Again, there are several choices of extractant, and the preferred one depends mainly on the type of soil under test. One of the most widely used procedures is the Olsen method (Olsen ef al., 1954), which was developed in the USA to correlate crop response to fertilizer on calcareous soils. The amount of P extracted will vary with temperature (increases by 0.43 mg P kg- per degree rise between 20°C and 30°C) and shaking speed, so conditions should be standardized. The extractant is 0.5 M sodium bicarbonate adjusted to pH 8.5. The bicarbonate competes with phosphate on the adsorption sites extracts, and removes most, but not all of it, together with some soluble calcium phosphate. Addition of phosphate-free activated carbon before shaking is necessary if coloured soil extracts are obtained, and then they will require filtration. 

The mechanism of action by which silane and siloxanes reduce expansion has been attributed to water repellence and air entrainment. Phosphate addition or coatings may interfere with the dissolution of silica gel and the formation of gel. It is also possible that phosphate reduces the osmotic potential and the swelling pressure in the gel. The manner in which air entrainment reduced expansion was attributed to the accommodation of alkali-silica gel in the air void system. For example, it was found that air-entrained concrete with 4% air voids could reduce AAR expansion by 40% [23]. 

Rabinowitz, M. B. 1993. Modifying soil lead bioavailability by phosphate addition. Bulletin of Environmental Contamination and Toxicology, 51, 438-444. 

The resistance of polymers to flame may be increased by the addition of halogenated compounds and antimony oxide. Organic phosphate additives inhibit the glow of the char formed in burning polymers. Polymers with chlorine pendant groups, such as PVC, and those with halogen-substituted phenyl groups, such as polyesters produced from tetrabromophthalic anhydride, are more flame-resistant than hydrocarbon polymers. 

Phosphate. Addition of secondary Na or K phosphate (i.e. Na2HP04 or K2HP04) causes the precipitation of colloidal calcium phosphate, with concomitant decreases in the concentration of soluble calcium and calcium ion. Polyphosphates, e.g. Na-hexametaphosphate, chelate Ca2+ strongly and dissolve CCP. 

The presence of low concentrations of phosphate has long been known to interfere with other fluorimetric analytical procedures this ability of trace amounts of phosphate to quench the fluorescence of chelates has been applied to the determination of the phosphates themselves. Several chelates were investigated measurement of the decrease of fluorescence of the aluminium-morin complex after phosphate addition proved to give the most satisfactory results65 (see Section II.B.2.a). 

The primary purpose of phosphate addition is to precipitate the hardness constituents. The calcium reacts with phosphate under the proper pH conditions to precipitate calcium phosphate as calcium hydroxyapatite, Cain(P04)fi(0H)2. This is a flocculent precipitate that tends to be less adherent to boiler surfaces than simple tricalcium phosphate, which is... 

Fig. 1.3 (continued) the 2 -positon but no phosphate. Additional sugars were also found connecting to the backbone of lipid A in F. tularensis (B), S. typhimuriu (C) and R. etli (D). The carbon position and the carbon number of fatty acid chains in lipid A are labeled... 

Covalent modification is a major mechanism for the rapid and transient regulation of enzyme activity. Numerous enzymes of intermediary metabolism are affected by phosphorylation, either positively or negatively. Covalent phosphorylations can be reversed by a separate subclass of enzymes known as phosphatases. The aberrant phosphorylation of growth factor and hormone receptors, as well as of proteins that regulate cell division, often leads to unregulated cell growth or cancer. The usual sites for phosphate addition to proteins are the serine, threonine and tyrosine R-group hydroxyl residues. 

M.B. Rabinowitz, Modifying soil and bioavailability by phosphate addition, Bull. Envirorc Contam. Toxicol., 51 (1993) 438-444. 

Traditional methods to map posttranslational modification sites, like those of phosphorylation, have been anchored by protein digest and mass spectroscopic (MS) approaches (for a review on the classic evaluation and for MS analyses of O-glycans, see Reference (56)). Unfortunately, like many posttranslational modifications, O-GlcNAcylation occurs routinely on a protein population with substoichiometric frequency, which results in a very small detectable population of a O-GlcNAc-modified product. Also, much like O-phosphate additions, the protein-O-GlcNAc bond is labile and is detached by collision-induced dissociation (CID) during MS analysis. Often, the bond is lost before it can be detected on the peptides analyzed (57, 58). Phosphate modifications, however, can overcome this limitation by emiching the peptide mixtures... 

Huang X. and Evangelou V. P. (1994) Suppression of pyrite oxidation rate by phosphate addition. In Environmental Geochemistry of Sulfide Oxidation (eds. C. N. Alpers and D. W. Blowes). American Chemical Society, Washington, DC 550, pp. 562-573. 

Most frequently, diphenyl and di-n-butyl phosphates are used. As such, Singh and coworkers [471-474] introduced the cyclic propane-1,3-diyl phosphates. Additionally, Seeberger and coworkers [277,475-482] have recently applied glycosyl phosphates for the synthesis of various oligosaccharides both in solution and in solid-phase syntheses. 

The enzyme phytase is able to hydrolyze the phosphate ester bonds of phytate, i.e. producing a more digestible inorganic phosphate from feedstuffs of vegetable origin. This avoids part of the inorganic phosphate addition in feedstuffs and reduces the phosphate content in pig faeces slurry by 30% [12]. 

In the Netherlands, all pig feedstuff nowadays contains phytase since it reduces the costs of both inorganic phosphate addition and environmental regulations. The application of phytase in the poultry industry, where similar problems exist, is growing. 

Allylic barium reagents prepared in this way can realize highly a-selective reactions with different electrophiles, e.g. cross-coupling reactions with allylic halides or allylic phosphates, additions to carbonyl compounds or imines, and ring opening of epoxides. A selective Michael addition reaction with an a,/ -unsaturated cy-cloalkanone can also be performed by use of an allylic barium reagent. 

Prokop, G., Schatnann, M., and Edelgaard, I. (2000). Management of Contaminated Sites in Western Europe, European Environment Agency, Copenhagen, Denmark, 1-171. Rabinowitz, M. B. (1993). Modifying soil lead bioavailability by phosphate addition. Bull. 

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