1. Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
2. Optical Radiology Lab, Mallinckrodt Institute of Radiology, Department of Radiology, Washington University School of Medicine, St. Louis, Missouri 63130, United States
3. Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
4. Department of Biochemistry and Molecular Biophysics, School of Medicine, Washington University in St. Louis, St. Louis, Missouri 63130, United States