1. Department of Applied Chemistry, School of Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
2. State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, Yinchuan 750021, P. R. China
3. Ministry of Forestry Bioethanol Research Center, Central South University of Forestry and Technology, Changsha 410004, P. R. China