1. Faculty of Pharmacy, Medical University of Sofia, 2, Dunav Street, Sofia 1000, Bulgaria
2. Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, Bl. 4, Sofia 1113, Bulgaria
3. Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, 109 Akad. G. Bonchev Street, Sofia 1113, Bulgaria
4. Institute of Physical Chemistry, Bulgarian Academy of Sciences, Akad. G. Bonchev Street, Bl.11, Sofia 1113, Bulgaria
5. Institute of Polymers, Bulgarian Academy of Sciences, Akad. G. Bonchev Street, Bl. 103A, Sofia 1113, Bulgaria