Received: 27 April 2018
Accepted: 12 August 2018
First Online: 18 August 2018
Compliance with ethical standards
: Author Min Wu, Yiqing Lv, Hua Xie, Yidong Liu, Weijing Ye, Yichen Huang, and Fang Chen declare that they have 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.