1. Laboratory of Chemical Physics Engineering (Formerly Laboratory of Thermodynamics and Physicochemical Hydrodynamics), Faculty of Chemistry, Sofia University, 1 James Bourchier Avenue, 1164 Sofia, Bulgaria, Colgate-Palmolive Technology Center, 909 River Road, Piscataway, New Jersey 08854-5596, and Colgate-Palmolive Research & Development, Inc., Avenue Du Parc Industriel, B-4041 Milmort (Herstal), Belgium