Acknowledgments
M. Wang thanks Hong Kong’s Research
Grants Council (RGC) for the financial support for this work through
research grants 17200519, 17202921, 17201622 and
N_HKU749/22 and also The University
of Hong Kong (HKU) for research grants in its Seed Fund for Basic
Research Scheme. S. Chen and J Lai thank HKU for providing them with PhD
scholarships. Assistance provided by members of M. Wang’s research group
and by technical staff in HKU’s Department of Mechanical Engineering,
Faculty of Dentistry and Electron Microscopy Unit is acknowledged.