1. Biosecurity and Nanosciences Laboratory, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, Department of Civil and Environmental Engineering, University of California, Los Angeles, 5731 Boelter Hall, Los Angeles, California 90095-1593, and Department of Chemical Engineering and Materials Science, University of California, Davis, 1 Shields Avenue, Davis, California 95616-5294