1. Hubei Engineering Technology Research Center of Environmental Purification Materials Hubei University of Education Gaoxin Road 129 Wuhan 430205 P. R. China
2. Department of Mechanical Engineering National University of Singapore Singapore 117575 Singapore
3. National University of Singapore Chongqing Research Institute Chongqing 401123 R. P. China
4. National University of Singapore Suzhou Research Institute Suzhou 215123 R. P. China