1. Centre for Ionics University Malaya, Department of Physics, University of Malaya, 50603 Kuala Lumpur, Malaysia
2. Centre for Foundation Studies, International Islamic University Malaysia, Jalan Universiti, 46350 Petaling Jaya, Selangor, Malaysia
3. Department of Physics, University of Peradeniya, 20400 Peradeniya, Sri Lanka
4. Institute of Biological Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia