1. National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou, P. R. China
2. School of Mathematics and Information Science, Henan Polytechnic University, Jiaozuo, P. R. China
3. School of Science, Xi’an University of Architecture and Technology, Xi’an, P. R. China
4. School of Mathematics, China University of Mining and Technology, Xuzhou, Jiangsu, P. R. China
5. Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia