1. School of Mathematics, Jilin University, Changchun 130012, People’s Republic of China.
2. School of Mathematics and Statistics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China, and Hubei Key Laboratory of Engineering Modeling and Scientific Computing, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China.
3. Corresponding author. Department of Mathematics, Champlain College Saint-Lambert, Saint-Lambert, QC J4P 3P2, Canada, and Department of Mathematics and Statistics, McGill University, Montreal, QC H3A 2K6, Canada.
4. Corresponding author. School of Mathematics and Statistics, Northeast Normal University, Changchun 130024, People’s Republic of China.