1. Departments of Mechanics and Mining and of Physical and Analytical Chemistry, EUP de Linares, University of Jaén, C/. Alfonso X el Sabio 28, 23700 Linares, Jaén, Spain, Institute of Chemistry, Karl-Franzens-Universität Graz, Heinrichstrasse 28, A-8010 Graz, Austria, and Department of Agricultural Engineering, ETSIAM, University of Córdoba, Avenida Menéndez Pidal s/n, 14080 Córdoba, Spain