1. Physical Chemistry 1, Chemical Center, Lund University, P.O. Box 124, SE-22100 Lund, Sweden, Centro de Estudos Farmacêuticos, Faculdade de Farmácia, Universidade de Coimbra, Coimbra codex P-3004-535, Portugal, and Building Materials, Lund University, P.O. Box 118, S-221 00 Lund, Sweden