1. Institute of Advanced Material Study, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816, Japan
2. Chemical Reseach Laboratory, Technical Headquarters, Nagasaki Research and Development Center, Mitsubishi Heavy Industries Limited, 5-717-1 Fukahori-machi, Nagasaki 851-03, Japan
3. Research and Development Center, Osaka Gas Company, Limited, 6-19-9 Torishima, Konohana-ku, Osaka 554, Japan