Funding for this research was provided by:
the State Key Laboratory of Space Medicine Fundamentals and Application, Chinese Astronaut Research and Training Center (SMFA15K02)
Received: 5 May 2019
Accepted: 13 August 2019
First Online: 22 August 2019
Ethics approval and consent to participate
: Not applicable.
: All co-authors have approved the submission of the manuscript for publication in its present form.
: The authors declare that they have no competing interests.