1. Department of Chemistry, Faculty of Science and Engineering, John Dalton Building, Manchester Polytechnic, Chester Street, Manchester M1 5GD, United Kingdom
2. Instituto Plasticos y Caucho, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain
3. Institute of Photographic Sciences, Academia Sinica, Beijing, China
4. Ward-Blenkinsop and Company Ltd., Halebank Industrial Estate, Lower Road, Widnes, Cheshire WA8 8NS, United Kingdom