1. School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K.
2. School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K.
3. Biophysics Group, Department of Physics, Faculty of Science, Mansoura University, Mansoura, Egypt
4. School of Medicine, University of Leeds, Leeds LS2 9JT, U.K.
5. Leeds Institute of Medical Research, University of Leeds, Leeds LS2 9JT, U.K.