Lili Feng, Guo Gao, Peng Huang, Xiansong Wang, Chunlei Zhang, Jiali Zhang, Shouwu Guo and Daxiang Cui*
* Corresponding author: Daxiang Cui dxcui@sjtu.edu.cn
Nanoscale Research Letters 2011, 6:551 doi:10.1186/1556-276X-6-551