1. Department of Physics & Astronomy The University of North Carolina at Chapel Hill Chapel Hill NC 27599 US
2. Biomedical Research Imaging Center The University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA
3. Department of Pharmacoengineering and Molecular Pharmaceutics The University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA
4. Department of Biomedical Engineering The University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA