Li, Xiaojin
Guo, Hua
Duan, Hongyang
Yang, Yanlian
Meng, Jie
Liu, Jian
Wang, Chen
Xu, Haiyan
Article History
Received: 10 August 2015
Accepted: 12 October 2015
First Online: 5 November 2015
Competing interests
: The authors declare no competing financial interests.