1. School of Civil Engineering; Wuhan University; Wuhan Hubei 430072 China
2. Advanced Research Institute of Multidisciplinary Science; Beijing Institute of Technology; Beijing 100081 China
3. Department of Physics; University of Science and Technology Beijing; Beijing 100083 China
4. School of Materials Science and Engineering; Wuhan University of Technology; Wuhan Hubei 430070 China
5. Biosystems and Biomaterials Division; National Institute of Standards and Technology; Gaithersburg MD 20899 USA