1. Laboratoire de Thermodynamique et Physico-Chimie des Matériaux, Université Nangui Abrogoua, Abidjan, Côte d’Ivoire
2. Department of Physics, Kenyatta University P.O.BOX 43844-00100, Nairobi, Kenya
3. Department of Physics, Worcester Polytechnic Institute 100 Institute Road, Worcester MA, 01609-2280, United States