1. College of Mathematics, Huaibei Normal University, Huaibei 235000, P. R. China
2. Nanchang Institute of Technology, Nanchang 330044, P. R. China
3. Division of Biochemistry, Department of Pharmacology, College of Pharmacy, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
4. Department of Mathematics, Faculty of Science, Jiangsu University, Zhenjiang 212013, P. R. China
5. Department of Mathematics, Obour High Institute for Engineering and Technology, Cairo 11828, Egypt