1. Graduate School of Science and Engineering and Department of Earth Sciences, Waseda University, Nishiwaseda 1-6-1, Shinjuku-ku, Tokyo 169-8050, Japan, and Institut Européen des Membranes, UMR nο. 5635 CNRS-ENSCM-UMII, Université Montpellier II, CC047, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France