1. State Key Laboratory of Solid Lubrication; Lanzhou Institute of Chemical Physics; Chinese Academy of Sciences; Lanzhou 730000 China
2. University of the Chinese Academy of Sciences; Beijing 100049 China
3. Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application; Soochow University; Suzhou Industrial Park Suzhou 215123 China
4. Department Functional Morphology and Biomechanics; Zoological Institute of the University of Kiel; Am Botanischen Garten 1-9 D-24098 Kiel Germany