1. Institute of Nanotechnology and Bioengineering, School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, UK
2. Institute of Nanotechnology and Bioengineering, School of Computing, Engineering and Physical Sciences, University of Central Lancashire, Preston PR1 2HE, UK
3. Mathematics and Sciences Unit, College of Art and Applied Sciences, Dhofar University, P.O. Box 2509, 211 Salalah, Oman
4. Department of Physics, University of Liverpool, Liverpool L69 3BX, UK