1. Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
2. Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan
3. Institute of Materials Science and Engineering, National Central University, Taoyuan City 32001, Taiwan
4. Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China
5. Department of Physics, National Changhua University of Education, Changhua, Taiwan
6. Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan
7. Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10617, Taiwan