1. Department of Mechanical and Materials Engineering, University of Alabama at Birmingham, Birmingham, Alabama 35233, United States
2. Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35233, United States
3. Department of Environmental Health Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
4. Department of Physics, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, United States
5. Center for Nanoscale Materials and Bio Integration (CNMB), University of Alabama at Birmingham, Birmingham, Alabama 35233, United States