Effect of phosphate

The main value of salt-spray tests is in the evaluation of the effectiveness of phosphate coatings in restricting the spread of rust from scratches or other points of damage in a paint film. This feature is of particular interest to the motorcar industry, as vehicles are often exposed to marine atmospheres and to moisture and salt when the latter is used to disperse ice and frost from road surfaces. Great care is needed in the interpretation of a salt-spray test, as it has been found to favour thin iron phosphate coatings more than is justified by experience with natural weathering. In the motorcar industry the present custom is to use zinc phosphate coatings on the car bodies and all other parts exposed to the outside atmosphere. 

Barton JC, Conrad ME. 1981. Effect of phosphate on the absorption and retention of lead in the rat. 

Figure 10.25 Effect of phosphate stabiliser on Fe(m)-catalysed decomposition of hydrogen peroxide in absence of substrate [237]. Initial concentration 2.9 g/l H202, Phosphonate stabiliser 2 g/l, 95 °C, pH 12...

Figure 3.4. Effects of phosphate levels on Cd and Zn solution speciation in California soils that received sludge application (data extracted from Villarroel et al., 1993)...

Jackson B.P., Miller W.P. Effectiveness of phosphate and hydroxide for desorption of arsnic and selenium species from iron oxides. Soil Sci Soc Am J 2000 64 1616-1622. 

Ma L.Q., Rao G.N. Effects of phosphate rock on sequential chemical extraction of lead in contaminated soils. J Environ Qual 1997b 26 788-794. 

Fig. 3. Sorption of arsenate (ASO4) onto ferrihydrite or Al(OH)x in the presence of phosphate (PO4) or phosphate and malate (Mai) at 50% surface coverage of arsenate and at initial ASO4/PO4 molar ratio of 1.0 or 0.5. Arsenate and phosphate were added as a mixture (As04+P04 As04+2P04) or phosphate was added 24 hrs before arsenate (P04 before As04) or arsenate was added 24 hrs before phosphate (As04 before P04). Arsenate, phosphate and malate were added as a mixture (As04+ P04/Mal molar ratio of 1). The numbers in parenthesis indicate the effectiveness of phosphate in preventing arsenate sorption. From Del Gaudio (2005).

Effect of Phosphate on the Removal of Arsenic Coprecipitated with or Sorbed on Metal Oxides... 

Hogstad, S., Svenneby, G., Torgner, I. A. etal. Glutaminase in neurons and astrocytes cultured from mouse brain kinetic properties and effects of phosphate, glutamate, and ammonia. Neurochem. Res. 13 383-388,1988. 

Phosphate in combination with NaCl has a beneficial effect on the waterbinding capacity of processed meat products for a detailed description, see Schmidt.227 The effect of phosphates is suggested to be alterations in pH or ionic strength, sequestration of metal ions, dissociation of actomyosin and depolymerisation of myosin.103,104,228,229 However, before action, added phosphates must be hydrolysed by muscle phosphatases or non-enzymatically. Belton et al.230 studied the hydrolysis of pyrophosphate and tripolyphosphate in comminuted chicken meat using 31P NMR spectroscopy, and found that the rate of hydrolysis was dependent on the length of ageing period of the muscle as well as the presence of NaCl. Li et al.231 studied the hydrolysis of various types of phosphates in intact chicken muscle with a similar approach by 31P NMR spectroscopy and thereby demonstrated differences in rate of hydrolysis of various phosphates. The findings of these studies... 

In attempting to reconcile these findings, it should be pointed out that rats may not be appropriate models for the study of calcium metabolism in humans. Unlike humans, the rat does not undergo epiphyseal plate closure and does not have a significant haversian remodeling sequence (21) Furthermore, rats excrete only l-270 of their calcium intake in their urine whereas humans excrete approximately 20-30% or more. This fact is especially significant, since most of the known effects of phosphates on calcium retention in humans are effected by alterations in urinary calcium. 

Christofferson, J., M. R. Christoffersen, W. Kibalczyc, and W. G. Perdok (1988), "Kinetics of Dissolution and Growth of Calcium Fluoride and Effects of Phosphate", Acta Odontol Scand. 46, 325-336. 

In an investigation of the physical basis of the interaction of histones with DNA, De Petrocellis et al.< 95 > have examined the effect of phosphate ions on histone HI. Binding results have shown that there are high-affinity sites for phosphate ions. In addition, phosphate ions were found to perturb the absorption spectra of HI and quench tyrosine fluorescence. Binding of the phosphate group resulted in positive difference absorption bands near 275 and 293 nm, which are similar to those produced at acid and alkaline pH, respectively. 

O. Shimizu, J. Watanabe, and K. Imakubo, Effect of phosphate ion on fluorescence characteristics of tyrosine and its conjugate base, Photochem. Photobiol. 29, 915-919 (1979). 

Figure 18.1. The effect of phosphate and methyl viologen MV) on hydrogen evolution from a mild steel surface.

The effect of phosphate on alkaloid production has also been evaluated (138). Using a modified induction medium devoid of phosphate and other essential growth factors, production of secondary compounds was more rapid than when phosphate was present. A broader study of the phenomenon has been reported by a French group (139) where, using three alkaloids as markers, the disappearance of the major nutrients from the medium and the evolution of phosphates, nitrates, ammonium ions, glucose, and starch in the cells were observed over time. It was not possible to relate alkaloid accumulation to the appearance or disappearance of any one metabolite in particular. However, other workers have found that the rate of biomass accumulation was directly related to the rate of formation of cellular serpentine (40) (140). 

Figure 5 shows the effect of phosphate concentration on crystallization rate Rg. Crystallization rate was obtained by weighing seeds in the reactor periodically, in which phosphate concentration drop in the bed was low enough, not to produce concentration distribution, by making the depth of the bed thin. Solubility of hydroxyapatite is so low, that the influent phosphate concentration is equal to super saturation dC. As shown in Figure 5, crystallization rate was proportional to 1.1th order of supersaturation. 

N3. Nisselbaum, J. S., Effect of phosphate and other anions on measurement of the activities of the isozymes of rat liver aspartate aminotransferase. Anal. Biochem. 23, 173-181 (1968). ... 

Galvez, N. Barr6n,V. Torrent,. J. (1999 a) Effect of phosphate on the crystallization of hematite, goethite, and lepidocrodte from ferrihydrite. Clays Clay Miner. 47 304-311 Gancedo, J.R. Grada, M. Marco, J.F. Pala-dos, J. (1988) Comparative Mossbauer and SEM study of the corrosion reaction of iron and weathering steel in SO2 polluted atmospheres. Hyperfine Interactions 41 637-640... 

Izumi, F. (1993) Rietveld analysis program RIE-TAN and PREMOS and special applications. In Young, R.A. (ed.) The Rietveld Method, Oxford, Oxford University Press, 236-253 Jackson, B.P. Miller, W.P. (2000) Effectiveness of phosphate and hydroxide for desorption of arsenic and selenium species from iron oxides. Soil Sci. Soc. Am. J. 64 1616-1622 Jain, A. Raven, K.P. Loeppert, R.EI. (1999) Ar-senite and arsenate adsorption on ferrihy-drite Surface charge reductions and net OEI-release stoichiometry. Environ. Sci. Techn. 

Acta Cryst. B39 165-170 Pauling, L. Hendricks, S.B. (1925) The crystal structures of hematite and corundum. J. Am. Chem. Soc. 47 781-790 Pauling, L. (1929) The principles of determining the structure of complex ionic crystals. J. Amer. Chem. Soc. 51 289-296 Payne, J.E. Davis, J.A. Waite,T.D. (1996) Uranium adsorption on ferrihydrite — effect of phosphate und humic add. Radiochemica Acta 74 239-243... 

Stanforth, R. Qiu, J. 2001. Effect of phosphate treatment on the solubility of lead in contaminated soil. Environmental Geology, 41, 1-10. 

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