Ying, Liu
Article History
Received: 28 March 2018
Accepted: 1 July 2018
First Online: 19 July 2018
Compliance with ethical standards
:
: The author declares that there is no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.