An improved procedure for preciee meaeurement of chlorine isotope ratioe in geological eamplee baeed on CerC1+ ion by thermal ioniration maee epectrometry ie reported. Uaing thie procedure the a'Cl/aaCl ratio of N18T SRM 976 ie determined to be 0.318929f0.000028(1~) 1296 XIAO, ZHOU, AND LIU with a precieion of 0.009%(1a). The procedure hae been eucceeefully applied t o etudy t h e variation of chlorine ieotopic aompoeitione in seawater and t o determine atomic weight of chlorine.

This article introduced the formation of an unsaturated plyester/diol-poIyurethane hybrid polymer networks(UPIPU HPNs). The phase behavior was exanuned by the dynamic mechanical properties and the morphology was investigated by transmission microscope(TEM) and atomic force microscopy(AFM) . The etrect of phase separation on mechanical properties is briefly described as well.