1. DOT GmbH 1 , Charles Darwin-Ring 1a, Rostock D-18059, Germany
2. Chair of Materials Science, Faculty of Mechanical Engineering and Marine Technology, University of Rostock 2 , Albert-Einstein-Str. 2, Rostock D-18059, Germany
3. MSC Medical Surface Consulting 3 , Heulerweg 5, Rostock D-18059, Germany