1. Niederrhein University of Applied Sciences; Department of Chemistry and Institute for Coatings and Surface Chemistry; Adlerstr. 32 D-47798 Krefeld Germany
2. Ivoclar Vivadent AG; Bendererstrasse 2 FL-9494 Schaan Liechtenstein
3. Leibniz Institute of Plant Biochemistry; Weinberg 3 D-06120 Halle (Saale) Germany