Acknowledgement. This research of the first author was partly supported by the National Natural Science Foundation of China (No. 11401184 and No. 11571216), the Construct Program of the Key Discipline in Hunan Province, the Science and Technology Plan of Hunan Province (2016TP1020), the Fifty-ninth Batch of Post Doctoral Foundation of China (No. 2016M590492) and the Post Doctoral Foundation of Jiangsu Province (No. 1601182C).