Wang, Gang
Huang, Baibiao
Li, Zhujie
Lou, Zaizhu
Wang, Zeyan
Dai, Ying
Whangbo, Myung-Hwan
Article History
Received: 28 October 2014
Accepted: 23 January 2015
First Online: 25 February 2015
Competing interests
: The authors declare no competing financial interests.