1. Department of Prosthodontics; School of Dental Medicine; University of Bern; Bern Switzerland
2. Department of Preventive and Restorative Sciences; School of Dental Medicine; Robert Schattner Center; University of Pennsylvania; Philadelphia PA USA
3. PENN Regional Nanotechnology Facility; School of Engineering and Applied Science; University of Pennsylvania; Philadelphia PA USA
4. Ioffe Institute; St. Petersburg,Russian Federation