Liu, Yaping
Li, Chengjun
Gao, Jingkun
Wang, Wenlong
Huang, Li
Guo, Xuezhu
Li, Bin
Wang, Jianjun
Article History
Received: 22 July 2014
Accepted: 2 October 2014
First Online: 21 October 2014
Competing interests
: The authors declare no competing financial interests.