Phosphate chain lengths

One key experimental observation regarding the ZP films is that the films found on the tops of asperities are stiffer and exhibit chemical spectra indicative of longer phosphate chain lengths than films found in the valleys between asperities. These observations that differences in the conditions at the two distinct locations alter the elastic and chemical properties of the films. One of the key differences between the tops of asperities and the valleys is the pressure experienced by the zinc phosphates. Since the highest pressures, and greatest potential for wear, are achieved at the tops of the asperities, determining the response of ZPs to these pressures may aid in developing a clear picture of how the anti-wear films work. 

Very recently, Brown and co-workers65 published a concise paper in which they presented short review of the possibilities and limitations of the refocused INADEQUATE and refocused INADEQUATE spin-echo (REINE) NMR spectroscopy. The authors discussed how these experiments can be used for obtaining various structural parameters, for example identification phosphate units, phosphate chain length, 2/p p couplings and correlation with chemical shift. It is worthy of note that the approach presented there can be applied not for phosphate glasses alone. 

Phosphates, which react with calcium to reduce the calcium ion activity, assist in stabilizing calcium-sensitive proteins, eg caseinate and soy proteinate, during processing. Phosphates also react with milk proteins. The extent of the reaction depends upon chain length. Casein precipitates upon addition of pyrophosphates, whereas whey proteins do not. Longer-chain polyphosphates cause the precipitation of both casein and whey proteins. These reactions are complex and not fully understood. Functions of phosphates in different types of dairy substitutes are summarized in Table 9 (see also Food additives). 

Step 3 of Figure 29.3 Alcohol Oxidation The /3-hydroxyacyl CoA from step 2 is oxidized to a /3-ketoacyl CoA in a reaction catalyzed by one of a family of L-3-hydroxyacyl-CoA dehydrogenases, which differ in substrate specificity according to the chain length of the acyl group. As in the oxidation of sn-glycerol 3-phosphate to dihydroxyacetone phosphate mentioned at the end of Section 29.2, this alcohol oxidation requires NAD+ as a coenzyme and yields reduced NADH/H+ as by-product. Deprotonation of the hydroxyl group is carried out by a histidine residue at the active site. 

Because of its superior solubility characteristics, a high 2-phenyl LAS (with an alkyl chain length average of 11.4) was the preferred type. The detergency performance of one LAS/AE type of formulation was discussed previously (see Figs. 12 and 13). Early commercial heavy-duty liquid (HDL) formulations were built with phosphate, but since 1979 almost all U.S. HDLs have been formulated without phosphate. 

Phosphated and Polyphosphated Alcohols In most cases aliphatic alcohols with a chain length in the range of 10-20 carbon atoms are converted with phosphorus pentoxide. A mixture of alkyl dihydrogen esters (primary) and dialkyl hydrogen esters (secondary) are yielded. 

In aq soln HgjfNOjfj reacts with Na4P207 (Na4L) to form complex ions with the formulas [Hg2(OH)L] and [Hg2L2r. The tripolyphosphate [PjO,)] " and tetrapolyphosphate [P40 3] ions form similar complex ions. The stability of these complex phosphates decreases as the chain length increases. The dicarboxylic acids oxalic, dimethylmalonic and succinic, H2L, form complexes with Hg2 ions ... 

The synthesis of linear 4 —> 1-a-D-glucans from D-glucopyranosyl phosphate by the action of phosphorylases has been shown by comparison of results of methylation and end-group assay and viscosity determination,209 and by potentiometric, iodine titrations82 on the product. The chain length of the enzymic product (100 to 200 D-glucose units) is less than that of the natural component. Whether this is due to impure enzymes cannot yet... 

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