1. College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, P. R. China
2. SNational Forestry and Grassland Administration Key Laboratory of Plant Fiber Functional Materials, Fujian Agriculture and Forestry University, Fuzhou 350002, P. R. China
3. School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
4. Material Science and Engineering College, Northeast Forestry University, Harbin 150040, P. R. China