1. Beijing Key Laboratory of Lignocellulosic Chemistry Beijing Forestry University No. 35, Tsinghua East Road, Haidian District Beijing 100083 P. R. China
2. Engineering Research Center of Forestry Biomass Materials and Energy Ministry of Education Beijing Forestry University No. 35, Tsinghua East Road, Haidian District Beijing 100083 P. R. China
3. Department of Bioproducts and Biosystems Engineering University of Minnesota Minneapolis MN 55108 USA