1. Department of Polymer Science and Technology; University of Calcutta; 92 A.P.C. Road Kolkata 700009 India
2. Department of Chemical and Biological Engineering; Industrial Membrane Research Institute, University of Ottawa; 161 Louis Pasteur Street Ottawa Ontario K1N 6N5 Canada
3. Department of Electronic Science; University of Calcutta; 92 A.P.C. Road Kolkata 700009 India
4. Department of Chemistry; West Bengal State University; Barasat Kolkata 700 126 India