About the Authors

Ka-Ming Wai

bhkmwai@cityu.edu.hk (K-MW); peter.yu@cityu.edu.hk (PY)

Affiliation Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, SAR, China

Peter K. N. Yu

bhkmwai@cityu.edu.hk (K-MW); peter.yu@cityu.edu.hk (PY)

Affiliation Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, SAR, China

Ka-Se Lam

Affiliation Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, SAR, China

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: WKM PKNY. Performed the experiments: WKM. Analyzed the data: WKM. Contributed reagents/materials/analysis tools: WKM KSL. Wrote the paper: WKM PKNY.