1. Department of Industrial Chemistry and Materials Engineering, University of Messina, Contrada di Dio, I-98166 Messina, Italy, Department of Mechanics and Materials, University “Mediterranea”, Loc. Feo di Vito, I-89122 Reggio Calabria, Italy, and CNR, Institute for Chemical Physical Processes, Messina Section, Salita Sperone, Contrada Papardo, Faro Superiore I-98158 Messina, Italy