1. College of Chemical Engineering; China University of Mining and Technology; Xuzhou 221116 Jiangsu P.R. China
2. College of Chemical Engineering and Material Science; Zaozhuang University; Zaozhuang 277160 Shandong P.R. China
3. Department of Chemistry and Volen Center for Complex Systems, MS 015; Brandeis University; Waltham MA 02454-9110 USA