1. Lappeenranta University of Technology, Packaging Technology, P.O. Box 20, FI-53851 Lappeenranta, Finland
2. Lappeenranta University of Technology, Laboratory of Physics, P.O. Box 20, FI-53851 Lappeenranta, Finland
3. Vilnius University, Physics Faculty, Sauletekio Al. 9-3, LT-10222 Vilnius, Lithuania
4. University of Bialystok Vilnius Branch, Kalvariju Str. 143, LT-03101 Vilnius, Lithuania
5. Vilnius Gediminas Technical University, J. Basanavicius Str. 28, LT-03224 Vilnius, Lithuania
6. Aalto University, School of Chemical Technology, Bioproduct Chemistry, P.O. Box 16300, FI-00076 Aalto, Finland