1. Department of Physics, East Carolina University, Greenville, North Carolina 27858-4353, United States
2. Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, U.K.
3. Department of Molecular Biology and Biophysics, UCONN Health, Farmington, Connecticut 06030-3305, United States
4. School of Electronic Engineering, Dongguan University of Technology, Dongguan, Guangdong 523808, P. R. China