1. School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70211 Kuopio, Finland
2. Department of Technical Physics, Faculty of Science, Forestry and Technology, University of Eastern Finland, 70211 Kuopio, Finland
3. Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5E, P.O. Box 56, 00014 Helsinki, Finland