Gou, Maling
Qu, Xin
Zhu, Wei
Xiang, Mingli
Yang, Jun
Zhang, Kang
Wei, Yuquan
Chen, Shaochen
Article History
Received: 6 November 2013
Accepted: 2 April 2014
First Online: 8 May 2014
Competing interests
: The authors declare no competing financial interests.