1. Department of Mathematics, Faculty of Science, Beijing University of Technology, Beijing 100022, China.
2. Corresponding author. School of Science, Changchun University, Changchun 130022, China.
3. Department of Mathematics, Champlain College Saint-Lambert, Quebec, J4P 3P2, Canada, and Department of Mathematics and Statistics, McGill University, Montreal, Quebec, H3A 2K6, Canada.
4. Université Clermont Auvergne, CNRS, Laboratoire de Mathématiques Blaise Pascal, 63000, Clermont-Ferrand, France.
5. Corresponding author. School of Mathematics and Statistics, Northeast Normal University, Changchun 130024, China.