Biocompatible materials such as porous bioactive calcium phosphate ceramics or titanium are regularly applied in dental
surgery: ceramics are used to support the local bone regeneration in a given defect, afterwards titanium implants replace
lost teeth. The current gold standard for bone reconstruction in implant dentistry is the use of autogenous bone grafts.
But the concept of guided bone regeneration (GBR) has become a predictable and well documented surgical approach
using biomaterials (bioactive calcium phosphate ceramics) which qualify as bone substitutes for this kind of application
as well. We applied high resolution synchrotron microtomography and subsequent 3d image analysis in order to
investigate bone formation and degradation of the bone substitute material in a three-dimensional manner, extending the
knowledge beyond the limits of classical histology. Following the bone regeneration, titanium-based implants to replace
lost teeth call for high mechanical precision, especially when two-piece concepts are used in order to guaranty leak
tightness. Here, synchrotron-based radiography in comparison with classical laboratory radiography yields high spatial
resolution in combination with high contrast even when exploiting micro-sized features in these kind of highly
attenuating objects. Therefore, we could study micro-gap formation at interfaces in two-piece dental implants with the
specimen under different mechanical load. We could prove the existence of micro-gaps for implants with conical
connections as well as to study the micromechanical behavior of the mating zone of conical implants during loading. The
micro-gap is a potential issue of failure, i. e. bacterial leakage which can induce an inflammatory process.
Optical coatings are widely used in optical instrumentation for astronomical and space applications. The required optical components are similar to the ones necessary for ground-based instrumentation: antireflection coatings, mirrors, transmission filters. In addition, depending on the specific application, resistance to the radiation induced damage is needed. The analysis here is limited to optical components for instruments to be used for Earth observation from the polar sun-synchronous orbit, where they will withstand a total radiation dose of 50 Gy accumulated during a typical lifetime of 5 years. In this work a set of optical coating materials were submitted to γ irradiation at the 60Co radioisotope source (ENEA Research Center) in order to simulate the hostile radiation environment in which they will be employed. The selected coatings are made with a multilayer structure that contains oxide layers and/or metal layers. Before the coating irradiation, the behavior of single-layer materials was investigated by comparing their reflectance and transmittance before and after the γ-ray exposure. Results are reported for a number of oxide single layers (SiO2, HfO2, Y2O3), metal layers (Ag, Al) and multilayer coatings made with these materials, by the physical vapor deposition (PVD) technique. The behavior of different substrates (glass, quartz) is also compared.
A group of of heavy germanate glasses containing BaO and/or Gd2O3, La2O3, SnO and doped with the scintillating rare earth Tb3+ are presented. Photoluminescence measurements are made on these glasses. The intensity of emission peaks is found proportional to the contents of Tb3+ dopants as well as of Gd3+: the former indicates that no obvious concentration quenching effect is visualized within the limits of present Tb3+ dopant while the latter is related to the enhanced energy transfer process from Gd3+ to Tb3+ centers.