Zhang, Zhiguo
Zhang, Huizhi
Li, Bo
Meng, Xiangjian
Wang, Jiqiu
Zhang, Yifei
Yao, Shuangshuang
Ma, Qinyun
Jin, Lina
Yang, Jian
Wang, Weiqing
Ning, Guang
Article History
Received: 15 August 2014
Accepted: 6 October 2014
First Online: 25 November 2014
Competing interests
: The authors declare no competing financial interests.