Liu, Qi
Li, Zhe-Fei
Liu, Yadong
Zhang, Hangyu
Ren, Yang
Sun, Cheng-Jun
Lu, Wenquan
Zhou, Yun
Stanciu, Lia
Stach, Eric A.
Xie, Jian
Article History
Received: 13 June 2014
Accepted: 16 December 2014
First Online: 20 January 2015
Competing interests
: The authors declare no competing financial interests.