Yafang Xue, Qian Liu, Guanjie He, Kaibing Xu, Lin Jiang, Xianghua Hu and Junqing Hu*
* Corresponding author: Junqing Hu hu.junqing@dhu.edu.cn
Nanoscale Research Letters 2013, 8:49 doi:10.1186/1556-276X-8-49