1. National Institute for Occupational Safety and Health, Health Effects Laboratory Division, Morgantown, WV, USA;
2. Department of Mechanical & Aerospace Engineering, West Virginia University, Morgantown, WV, USA;
3. Center for Environmental Health Sciences, University of Montana, Missoula, MT, USA;
4. Research Center for Exotic Nanocarbons, Shinshu University, Nagano-shi, Japan;
5. Departments of Physics, Chemistry, Materials Science & Engineering, and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, USA;
6. Department of Pharmaceutical Sciences, West Virginia University, Morgantown, WV, USA