1. State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal Materials School of Materials Science and Engineering Northwestern Polytechnical University Xi'an 710072 P. R. China
2. Key Lab for Space Biosciences and Biotechnology Research Center for Special Medicine and Health Systems Engineering School of Life Sciences Northwestern Polytechnical University Xi'an 710072 P. R. China
3. School of Food and Biological Engineering Shaanxi University of Science and Technology Xi'an 710021 P. R. China
4. State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou 730000 P. R. China