1. School of Mathematics and Physics Anhui University of Technology Maanshan 243002 P. R. China
2. School of Materials Science and Engineering Anhui University of Technology Maanshan 243002 P. R. China
3. Key Laboratory of Metallurgical Emission Reduction & Resources Recycling Anhui University of Technology), Ministry of Education Anhui University of Technology Maanshan 243002 P. R. China