NASH

Liddell P A, Kuciauskas D, Sumida J P, Nash B, Nguyen D, Moore A L, Moore T A and Gust D 1997 Photoinduced charge separation and charge recombination to a triplet state in a carotene-porphyrin-fullerene triad J. Am. Chem. Soc. 119 1400-5... 

E. C. Hohmann and D. B. Nash, "A Simphfted Approach to Heat Exchanger Network Analysis," 85th NationalAlChE Meeting, Philadelphia, Pa., June 1978. 

The differences in the amino acid chemistry of the hide coUagen and the hair keratin are the basis of the lime-sulfide unhairing system. Hair contains the amino acid cystine. This sulfur-containing amino acid cross-links the polypeptide chains of mature hair proteins. In modem production of bovine leathers the quantity of sulfide, as Na2S or NaSH, is normally 2—4% based on the weight of the hides. The lime is essentially an unhmited supply of alkah buffered to pH 12—12.5. The sulfide breaks the polypeptide S—S cross-links by reduction. Unhairing without sulfide may take several days or weeks. The keratin can be easily hydrolyzed once there is a breakdown in the hair fiber stmcture and the hair can be removed mechanically. The coUagen hydrolysis is not affected by the presence of the sulfides (1—4,7). 

Fig. 1. Density of sodium hydrosulfide solutions ia water, where the numbers on the vertical lines represent concentrations of NaSH ia wt % (1).

R. G. Nash and A. R. LesHe, eds.. Groundwater Residue Sampling Design, American Chemical Society, Washington, D.C., 1991. 

CHj—CHCOOH + HCl ClCH GHjCOOH ClCHjCHjCOOH + NaSH acidification 13... 

CHj—CHCN + NaSH NCGHjCH SCH GHjCN NGGHjGHjSGHjGHjGN + NaSH + NaOH acidification 18... 

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