1. Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany
2. Mechanics Division, Department of Mathematics, University of Oslo, N-0851 Oslo, Norway
3. Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland, Australia
4. Institute of Polymers and Composites, Hamburg University of Technology, Hamburg, Germany
5. Helmholtz-Zentrum Hereon, Institute of Surface Science, Geesthacht, Germany