1. Department of Mechanical Engineering, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, United States
2. Department of Mechanical and Aerospace Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
3. Department of Physics, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, United States
4. Department of Civil and Environmental Engineering, University of Houston, Houston, Texas 77204, United States
5. Materials Science and Engineering Program, University of Houston, Houston, Texas 77204, United States