1. School of Renewable Natural Resources, Louisiana State University, Baton Rouge, Louisiana 70803, United States
2. College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
3. Physics Department and Nano Materials Laboratory, Southern University and A&M College, Baton Rouge, Louisiana 70813, United States
4. Department of Forest Products, National Institute of Forest Science, Seoul 130-712, Korea