Hao, Panpan
Yang, Jianmin
Liu, Yanping
Zhang, Mingxiang
Zhang, Kai
Gao, Fei
Chen, Yuguo
Zhang, Cheng
Zhang, Yun
Article History
Received: 25 September 2014
Accepted: 27 January 2015
First Online: 5 March 2015
Competing interests
: The authors declare no competing financial interests.