Li, Diao
Jussila, Henri
Karvonen, Lasse
Ye, Guojun
Lipsanen, Harri
Chen, Xianhui
Sun, Zhipei
Article History
Received: 12 August 2015
Accepted: 7 October 2015
First Online: 30 October 2015
Competing interests
: The authors declare no competing financial interests.