Qiqing Chen,a Dayan Yang,a Luodan Yu,b Xiangxiang Jing*a and Yu Chen*b
a Department of Ultrasound, Hainan General Hospital, Haikou, P. R. China
b State Key Lab of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, P. R. China