Funding for this research was provided by:
National Key Basic Research Program of China (2013CB127700)
Special Fund for Natural Science Fund Project of Hebei Province (C2015204105)
Text and Data Mining valid from 2018-07-17
Accepted: 10 July 2018
First Online: 17 July 2018
Compliance with ethical standards
: The authors 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. This article does not contain any studies with animals performed by any of the authors.
: Informed consent was obtained from all individual participants included in the study.
: The manuscript has not been submitted to more than one journal for simultaneous consideration, and has not been published previously. This is a single study not being split up into several parts and not being submitted to various journals or to one journal over time. No data have been fabricated or manipulated to support our conclusions. We don’t plagiarism others’ data, text, or theories. Consent to submit has been received explicitly from all co-authors, as well as from the responsible authorities. All authors whose names appear on the submission have contributed sufficiently to the scientific work. We ensure the correct author group, corresponding author, and order of authors at submission.