1. Western Research Institute, Laramie, WY 82072, USA
2. LUKOIL Neftohim Burgas, 8104 Burgas, Bulgaria
3. Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Academic Georgi Bonchev 105, 1113 Sofia, Bulgaria
4. Department of Industrial Technologies and Management, University Prof. Dr. Assen Zlatarov, Professor Yakimov 1, 8010 Burgas, Bulgaria
5. Department of Mathematics, University of Chemical Technology and Metallurgy, Kliment Ohridski 8, 1756 Sofia, Bulgaria
6. Department of Chemical Engineering, University of Wyoming, 1000 E University Avenue, Laramie, WY 82071, USA