1. Professor, Dept. Chemical Engineering and Metallurgy, Univ. of Barcelona. Marti i Franquès, 1, 6a planta. 08028 Barcelona, Spain.
2. Dra., Dept. Chemical Engineering and Metallurgy, Univ. of Barcelona. Marti i Franquès, 1, 6a planta. 08028 Barcelona, Spain.
3. Professor, Dept. Chemical Engineering, North Carolina State Univ., 113 Riddick Hall, Raleigh, NC 27695-7905.