Chen, Bin-Bin
Wiium, Nora
Dimitrova, Radosveta
Chen, Ning
Article History
First Online: 17 July 2017
Compliance with Ethical Standards
: 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.
: Authors declare that they have no conflict of interest.
: Informed consent was obtained from all individual participants included in the study.