1. UNESCO UNISA Africa Chair in Nanosciences & Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, P. O. Box 392, Pretoria, South Africa
2. Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation of South Africa, 1 Old Faure Road, Somerset West 7129, Western Cape, South Africa
3. Nano Research Centre, Physics Department, B. S. Abdur Rahman University, Vandalur, Chennai 600 048, India