1. Chemical
Engineering Department, Universidad de La Frontera, Av. Francisco Salazar, 01145 Temuco, Chile
2. Department
of Physics, University of Bío-Bío, Av. Collao 1202, P.O. Box 5-C, 08101 Concepción, Chile
3. Chemical
Engineering Department and Surface Analysis Laboratory, University of Concepción, P.O. Box 160-C, 08101 Concepción, Chile