Clinical outcomes of different implant types in mandibular bar-retained overdentures: a retrospective analysis with up to 20 years follow-up.

PURPOSE To determine the clinical and radiological outcomes of hybrid-design- (HD) and bone-level (BL) implants for bar-retained mandibular implant-overdentures (IODs). METHODS For this retrospective study, edentulous patients who had received maxillary complete dentures and mandibular bar-retained IODs were invited for a follow-up assessment. Implant survival, implant success and health of peri-implant tissues were assessed on an implant level-based analysis. Patient-based parameters served to identify risk factors for peri-implant bone loss, presence of peri-implantitis and success. RESULTS Eighty patients (median age 72.72 [67.03; 78.81] years, 46 females) with 180 implants (median follow-up 12.01 [10.82; 21.04] years) were assessed. There was no difference concerning the rate of implant failure (p = 0.26), or peri-implantitis (p = 0.97) between HD and BL implants. Solely in one study group, there was the presence of peri-implant pus. Implant success was higher in BL implants with one group being notably higher than the comparing groups (p = 0.045). For bone loss, a width of keratinized mucosa (KM) ≤ 1 mm (p = 0.0006) and the presence of xerostomia (p = 0.09) were identified as risk factors. Smoking (p = 0.013) and a higher body mass index (BMI) (p = 0.03) were a risk factor for peri-implantitis. As risk factors for reduced implant success, a small width of KM (p = 0.003) and the presence of xerostomia (p = 0.007) were identified. CONCLUSIONS For mandibular bar-retained IODs, both BL and HD implants are mostly successful. A minimum of 1 mm KM around implants and normal salivary flow are relevant factors for implant success and stable peri-implant bone levels. Smoking and a high BMI are potential risk factors for peri-implantitis

The use of atomic force microscopy for structural and surface morphological analysis of Fanconi anemia patient fibroblasts before and after exposure to γ-radiation

The surface morphological changes of Fanconi anemia patient fibroblasts after exposure to γ–radiation were investigated by AFM and foci immunofluorescence staining. The reorganization of the actin cytoskeleton was found, having resulted in reduction of the membrane stiffness and increase of adhesion in nuclear and lamellipodial regions of the cell

The role of defects in fluorescent silicon carbide layers grown by sublimation epitaxy

Donor-acceptor co-doped SiC is a promising light converter for novel monolithic all-semiconductor white LEDs due to its broad-band donor-acceptor pair luminescence and potentially high internal quantum efficiency. Besides sufficiently high doping concentrations in an appropriate ratio yielding short radiative lifetimes, long nonradiative lifetimes are crucial for efficient light conversion. The impact of different types of defects is studied by characterizing fluorescent silicon carbide layers with regard to photoluminescence intensity, homogeneity and efficiency taking into account dislocation density and distribution. Different doping concentrations and variations in gas phase composition and pressure are investigated

Coherent combining of two high-brightness laser diodes phase-locked by a Michelson-type external cavity (Orale)

International audienceWe describe a new coherent beam combin- ing architecture based on the passive phase- locking of two laser diodes in a Michelson external cavity on their rear side, and their coherent combination on their front side

Separate phase-locking and coherent combining of two laser diodes in a Michelson cavity

We describe a new coherent beam combining architecture based on passive phase-locking of two laser diodes in a Michelson external cavity on their rear facet, and their coherent combination on the front facet. As a proof-of-principle, two ridge lasers have been coherently combined with >90 % efficiency. The phase-locking range, and the resistance of the external cavity to perturbations have been thoroughly investigated. The combined power has been stabilized over more than 15 min with an optical feedback as well as with an automatic adjustment of the driving currents. Furthermore, two high-brightness high-power tapered laser diodes have been coherently combined in a similar arrangement; the combining efficiency is 70% and results in an output power of 4 W. We believe that this new configuration combines the simplicity of passive self-organizing architectures with the optical efficiency of master-oscillator power-amplifier ones

Measurement of mechanical vibrations excited in aluminium resonators by 0.6 GeV electrons

We present measurements of mechanical vibrations induced by 0.6 GeV electrons impinging on cylindrical and spherical aluminium resonators. To monitor the amplitude of the resonator's vibrational modes we used piezoelectric ceramic sensors, calibrated by standard accelerometers. Calculations using the thermo-acoustic conversion model, agree well with the experimental data, as demonstrated by the specific variation of the excitation strengths with the absorbed energy, and with the traversing particles' track positions. For the first longitudinal mode of the cylindrical resonator we measured a conversion factor of 7.4 +- 1.4 nm/J, confirming the model value of 10 nm/J. Also, for the spherical resonator, we found the model values for the L=2 and L=1 mode amplitudes to be consistent with our measurement. We thus have confirmed the applicability of the model, and we note that calculations based on the model have shown that next generation resonant mass gravitational wave detectors can only be expected to reach their intended ultra high sensitivity if they will be shielded by an appreciable amount of rock, where a veto detector can reduce the background of remaining impinging cosmic rays effectively.Comment: Tex-Article with epsfile, 34 pages including 13 figures and 5 tables. To be published in Rev. Scient. Instr., May 200

DEVELOPMENT OF DOPED NANOPOROUS CARBONS FOR HYDROGEN STORAGE

Hydrogen storage materials based on the hydrogen spillover mechanism onto metal-doped nanoporous carbons are studied, in an effort to develop materials that store appreciable hydrogen at ambient temperatures and moderate pressures. We demonstrate that oxidation of the carbon surface can significantly increase the hydrogen uptake of these materials, primarily at low pressure. Trace water present in the system plays a role in the development of active sites, and may further be used as a strategy to increase uptake. Increased surface density of oxygen groups led to a significant enhancement of hydrogen spillover at pressures less than 100 milibar. At 300K, the hydrogen uptake was up to 1.1 wt. % at 100 mbar and increased to 1.4 wt. % at 20 bar. However, only 0.4 wt% of this was desorbable via a pressure reduction at room temperature, and the high lowpressure hydrogen uptake was found only when trace water was present during pretreatment. Although far from DOE hydrogen storage targets, storage at ambient temperature has significant practical advantages oner cryogenic physical adsorbents. The role of trace water in surface modification has significant implications for reproducibility in the field. High-pressure in situ characterization of ideal carbon surfaces in hydrogen suggests re-hybridization is not likely under conditions of practical interest. Advanced characterization is used to probe carbon-hydrogen-metal interactions in a number of systems and new carbon materials have been developed