1. State
Key Laboratory of Polymer Physics and Chemistry, Changchun Institute
of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
2. Division
of Mathematics and Science, University of South Carolina Salkehatchie, Walterboro, South Carolina 29488, United States
3. Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States