Jin, L.
Xu, P. X.
Zeng, Y.
Lu, L.
Barthel, J.
Schulthess, T.
Dunin-Borkowski, R. E.
Wang, H.
Jia, C. L.
Article History
Received: 18 October 2016
Accepted: 24 November 2016
First Online: 19 January 2017
Competing interests
: The authors declare no competing financial interests.