Xu, Chuan
Wang, Libin
Liu, Zhibo
Chen, Long
Guo, Jingkun
Kang, Ning
Ma, Xiu-Liang
Cheng, Hui-Ming
Ren, Wencai
Article History
Received: 26 February 2015
Accepted: 1 July 2015
First Online: 17 August 2015
Competing interests
: The authors declare no competing financial interests.