1. Center for Energy Research, University of California at San Diego, 9500 Gilman Dr. La Jolla, CA 92093-0417, USA
2. Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan
3. Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan