N.m.r. of solid biopolymers

The dynamical behaviour of four solid polypeptides (α-chymotrypsin, insulin, lysozyme, ribonuclease A) has been investigated by proton magnetic relaxation. The interpretation was supplemented by measurements on the constituent amino acids, and on dipeptides, tripeptides and homopolypeptides. The following motions were identified and characterized: methyl group reorientation, segmental motion, sidechain motion, proline ring puckering, reorientation of water molecules in the structure. Slow motions were investigated through measurements of the dipolar relaxation time T_ID.     

M.A.L.D.I.-T.O.F. mass spectrometry characterization of 4-alkyl substituted phenol-formaldehyde novalac type resins

Two methods of synthesis for 4-alkyl substituted phenol-formaldehyde resins are described. A common method for synthesis of novolac type phenol-formaldehyde resin uses sulfuric acid catalyst in the presence of xylene for azeotropic removal of water of reaction. By the use of M.A.L.D.I.-T.O.F. mass spectrometry we have demonstrated that m-xylene is incorporated into these polymers. Polymers free of impurities are best prepared using a cation exchange resin as catalyst in the presence of a less reactive solvent, e.g. chlorobenzene, or in the absence of solvents. © 1997 Elsevier Science Ltd.     

中国洗涤用品工业协会赴美国考察报告

应美国洗涤剂协会(SDA)的邀请,经中国轻工业联合会批准,中国洗涤用品工业协会组团,于2002年5月13日至27日对美国进行行业考察.