1. Department of Chemical Engineering, University of Illinois Urbana−Champaign, 118 RAL, MC-712, Box C-3, Urbana, Illinois 61801
2. DuPont Company, Central Research and Development, Experimental Station, P.O. Box 80228, Wilmington, Delaware 19880-0228
3. Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802