1. Center of Physics of Fibrous Soft Matters, Dong Hua University, Shanghai, 200051, China
2. Center of Physics of Fibrous Soft Matters, Dong Hua University, Shanghai, 200051, China; tel.: 8621 6237 3602; fax: 8621 6219 3061
3. Division of Textiles and Clothing, Biological and Agricultural Engineering Department, University of California, Davis, CA 95616, USA