We thank the referee for providing constructive comments and help in improving this paper. This research was partly supported by the National Natural Science Foundation of China (No. 11571216 and No. 11801159), the Science and Technology Plan Project of Hunan Province (No. 2016TP1020), the Science and Technology Plan Project of Hengyang City (2017KJ183), and the Construct Program of the Key Discipline in Hunan Province.
Acknowledgements We thank the referee for providing constructive comments and help in improving this paper. This research was partly supported by the National Natural Science Foundation of China (No. 11571216 and No. 11801159), the Science and Technology Plan Project of Hunan Province (No. 2016TP1020), the Science and Technology Plan Project of Hengyang City (2017KJ183), and the Construct Program of the Key Discipline in Hunan Province.