Phosphotungstic add

Most alkaloids are isolated from plant extracts by conversion into the difficultly soluble salts which they form with complex acids such as hexachloroplatinic acid, chlorauric add, phosphotungstic add, hydroferro-cyanic add, Rdnecke s add, etc. Perchloric add, picric add, flavianic add, mercuric chloride, iodine in potassium iodide are also used. 

Other metals can be similarly immobilised. Silica- and clay-supported rhodium complexes, for example, are effective hydrogenation catalysts.160,161 An interesting variant on this involves a heteropolyacid to assist the metal-support binding. The heteropolyadd, such as phosphotungstic add, is attached to the support (e.g. montmorillonite) by the indpient wetting technique. The solid material is then treated with a solution of the homogeneous catalyst such as Rh(DiPamp).162... 

The part of the peptone precipitable by phosphotungstic add is sometimes designated by the name of true peptone, an... 

We shall see in a subsequent chapter what is to be thought of the presence here of the albumoses and the peptones. Let us pause for the moment in consideration of the end products, which form the greater part of tryptic hydrolysis. And first of all, it should be noted that these crystalline compounds, non-biuretic and not precipitable by phosphotungstic add, have absolutely nothing in common with those of the corresponding fraction obtained in peptic action whereas the former are very simple amino-acids, the latter are compoimds, capable even of being transformed by degradation into peptones. 

Fig. 13.30 A TEM micrograph of Nylon-6 modified with EPDR rubber in which rubber particles are surrounded by preferentially ordered parallel crystalline lamellae forming material layers of low plastic resistance. The micrograph was stained with phosphotungstic add, which makes crystalline lamellae stand out over a stained amorphous background (from Muratoglu et al. (1995b) courtesy of Elsevier).

Giordano, N., Staiti, R, Hocevar, S., and Arico, A. S., 1996, High performance fuel cell based on phosphotungstic add as proton conducting electrolyte, Electrochim. Acta 41 397-403. 

Synthesis and characterization of P2O5-Si02-X (X = phosphotungstic add) glasses as electrolyte for low temperature H2/O2 fuel cell application./, Memb. Sci, 280 (1-2), 744-751. 

Nafion membranes have also been used as porous supports to modify and improve the electrochemical properties of the membrane for fuel cell applications. Examples for such membranes are PDDA/phosphotungstic add (PWA)-Nafion composite membranes, PDDA-PSS-PAZO-Nafion membranes (PAZO poly(l-(4-(3-carboxy-4-hydroxyphenylazo) benzene sulfonamido)-l,2-ethanediyl soditrm salt), and Nafion and sulfonated polyetheretherketone membranes. ... 

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