About the Authors

William Letsou

Affiliation Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America

Long Cai

lcai@caltech.edu

Affiliation Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: LC WL. Performed the experiments: WL. Analyzed the data: WL LC. Contributed reagents/materials/analysis tools: WL. Wrote the paper: WL LC.