Wang, Ping
Zhao, Liang
Liu, Jason
Weir, Michael D
Zhou, Xuedong
Xu, Hockin H K
Article History
Received: 18 June 2014
Revised: 25 July 2014
Accepted: 29 July 2014
First Online: 30 September 2014
Competing interests
: The authors declare no conflict of interest.