1. Key Laboratory of Bio-Based Material Science and Technology (Ministry of Education) , Northeast Forestry University , Harbin 150040 , P.R. China
2. Key Laboratory of Bio-Based Material Science and Technology (Ministry of Education) , Northeast Forestry University , Harbin 150040 , P.R. China , Tel./Fax: +86-451-82191961
3. Department of Mechanical and Energy Engineering , University of North Texas , 3940 N Elm St., Suite F101 , Denton, TX 76207 , USA