1. Faculty of Science, Yibin University, Yibin 644000, Sichuan, P. R. China
2. Department of Bionanotechnology, Hanyang University, Ansan 155-88, South Korea
3. Faculty of Materials and Chemical Engineering, Yibin University, Yibin 644000, P. R. China
4. Department of Mathematics, College of Science, Taif University, Taif 21944, Saudi Arabia
5. Department of Mathematics, College of Science Al-Zulfi, Majmaah University, Al Majmaah 11952, Saudi Arabia