Hong, Xiaoping
Kim, Jonghwan
Shi, Su-Fei
Zhang, Yu
Jin, Chenhao
Sun, Yinghui
Tongay, Sefaattin
Wu, Junqiao
Zhang, Yanfeng
Wang, Feng
Article History
Received: 6 February 2014
Accepted: 16 July 2014
First Online: 24 August 2014
Competing interests
: The authors declare no competing financial interests.