Funding for this research was provided by:
National Natural Science Foundation of China (61301095)
Key Development Program of Basic Research of China (JCKY2013604B001)
Fundamental Research Funds for the Central Universities (GK2080260148, HEUCF1508)
Article History
First Online: 15 December 2017
Compliance with ethical standards
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: All the authors declare that there is no conflict of interests regarding the publication of this article.