1. Department of Materials Technology, Faculty of Engineering, Chiba University, Inage, Chiba 263, Japan, Fine Chemicals Research Laboratory, Nisshin Flour Milling Company, Ltd., Iruma, Saitama 356, Japan, “Form and Function”, PRESTO, Japan Science and Technology Corporation, Inage, Chiba 263, Japan, and Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute, Takasaki, Gunma 370-12, Japan