1. Department of Chemistry, University of Georgia, Athens, Georgia 30602
2. Research Institute of Tropical Agriculture, University of Ryukyu, Taketomi, Okinawa 907-1541, Japan
3. Graduate School of Human and Environmental Studies, Kyoto University, Sakyo, Kyoto 606-8501, Japan
4. Kyoto University of Education, Fushimi, Kyoto 612-0863, Japan