Liu, Jun-Liang
Wu, Jie-Yi
Huang, Guo-Zhang
Chen, Yan-Cong
Jia, Jian-Hua
Ungur, Liviu
Chibotaru, Liviu F.
Chen, Xiao-Ming
Tong, Ming-Liang
Article History
Received: 23 June 2015
Accepted: 16 October 2015
First Online: 17 November 2015
Competing interests
: The authors declare no competing financial interests.