[1] Professor, College of Public Health, Zhengzhou University, 2010-

[2] Visiting scholar, Department of Chemistry, University of Waterloo, Canada, 2013-2014

[3] Lecturer & Associate Professor, College of Public Health, Zhengzhou University, 2001-2009

[4] Lecturer, College of Public Health, Henan Medical University, 1996-2000

[5] Technician, Analysis and Testing Center, Henan Tongbai Yindongpo Gold Mine, 1991-1993