1. Department of Reproductive Medicine, The Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong 256603, P.R. China
2. Smart Division Gas, Qingdao iESLab Electronic Co., Ltd., Qingdao 266071, P.R. China
3. Department of Physiology, Qingdao University Medical College, Qingdao, Shandong 266071, P.R. China