1. Key Laboratory for Industrial Biocatalysis, Ministry of EducationDepartment of Chemical EngineeringTsinghua University Beijing 100084 P. R. China
2. State Key Laboratory of New Ceramics and Fine ProcessingSchool of Materials Science and EngineeringTsinghua University Beijing 100084 P. R. China
3. Applied Mechanics LaboratoryDepartment of Engineering Mechanics andCenter for Nano and Micro MechanicsTsinghua University Beijing 100084 P. R. China
4. State Key Laboratory of Bioreactor EngineeringEast China University of Science and Technology Shanghai 200237 P. R. China