Funding for this research was provided by:
Shandong Provincial Natural Science Foundation (ZR2017BA014)
Visiting scholarship from Shandong University of Science and Technology (0103014)
Development Program for Defense Department of China (C1520110002)
National Natural Science Foundation of China (61573008)
Article History
First Online: 3 December 2019
Compliance with Ethical Standards
:
: The authors have declared that no conflict of interest exists.