1. Department of Mechanical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
2. School of Chemical Engineering, The University of Queensland, St Lucia, Queensland 4072, Australia
3. School of Science and Technology, University of New England, Armidale, New South Wales 2351, Australia
4. School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, P. R. China
5. Department of Chemical Engineering, University of Wyoming, Laramie, Wyoming 82071, United States
6. Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden