1. Analytical Sciences, The Dow Chemical Company, 1897 Building, Midland, Michigan 48667; Department of Physics, North Carolina State University, Raleigh, North Carolina 27695; Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON L8S 4M1 Canada; Polyurethanes, Dow Chemical, Building B-1608, 2301 N. Brazosport Blvd., Freeport, Texas 77541; and Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061