1. Integrated Science Education and Research Centre (ISERC), Visva-Bharati, Santiniketan, West Bengal 731 235, India
2. Department of Mathematics, Government General Degree College, Ranibandh, Bankura, West Bengal 722 135, India
3. Department of Mechanical Engineering, Technology Faculty, Firat University, TR-23119 Elazig, Turkey
4. Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan