Zhang, Yunlong
He, Xiaoliang
Meng, Xingjun
Wu, Xiaojuan
Tong, Huichun
Zhang, Xiuping
Qu, Shaogang
Article History
Received: 15 July 2016
Revised: 5 November 2016
Accepted: 7 December 2016
First Online: 2 February 2017
Competing interests
: The authors declare no conflict of interest.