1. Materials Technology Research Group (MaTRec), School of Chemical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
2. Faculty of Resource Science and Technology, Universiti Malaysia Sarawak (UNIMAS), Kota Samarahan 94300, Malaysia
3. Open University of Sudan, Faculty of Education, Sciences Department, P.O. Box 13091, Khartoum, Sudan