Abstract
Photoluminescence and photomodulated reflectivity measurements of ZnOSe alloys are used to demonstrate a splitting of the valence band due to the band anticrossing interaction between ...localized Se states and the extended valence band states of the host ZnO matrix. A strong multiband emission associated with optical transitions from the conduction band to lower E
−
and upper E
+
valence subbands has been observed at room temperature. The composition dependence of the optical transition energies is well explained by the electronic band structure calculated using the
kp
method combined with the band anticrossing model. The observation of the multiband emission is possible because of relatively long recombination lifetimes. Longer than 1 ns lifetimes for holes photoexcited to the lower valence subband offer a potential of using the alloy as an intermediate band semiconductor for solar power conversion applications.
Background
Pertrochanteric fractures are increasing and their operative treatment remains under discussion. Failures needing reoperations such as a cut-out are reported to be high and are associated ...with multiple factors including poor bone quality, poor fracture reduction and improper implant placement. The PFNA
®
with perforated blade offers an option for standardized cement augmentation with a PMMA cement to provide more stability to the fracture fixation. It remains unclear if the augmentation of this implant does any harm in a longer time span. This prospective multicenter study shows clinical and radiological results with this implant with a mean follow-up time of 15 months.
Methods
In 5 European clinics, 62 patients (79 % female, mean age 85.3 years) suffering from an osteoporotic pertrochanteric fracture (AO 31) were treated with the augmented PFNA
®
. The primary objectives were assessment of activities of daily living, pain and mobility. Furthermore, the X-rays were analyzed for the cortical thickness index, changes of the trabecular structure around the cement and the hip joint space.
Results
The mean follow-up time was 15.3 months. We observed callus healing in all cases. The surgical complication rate was 3.2 % with no complication related to the cement augmentation. A mean volume of 3.8 ml of cement was injected and no complication was reported due to this procedure. 59.9 % reached their prefracture mobility level until follow-up. The mean hip joint space did not change significantly until follow-up and there were no signs of osteonecrosis in the follow-up X-rays. Furthermore, no blade migration was assessed.
Conclusion
This study makes us believe that the standardized augmentation of the PFNA with a perforated blade is a safe method to treat pertrochanteric femoral fractures. It leads to good functional results and is not associated with cartilage or bone necrosis.
The incorporation of Bi in GaSb1−xBix alloys grown by molecular beam epitaxy is investigated as a function of Bi flux at fixed growth temperature (275°C) and growth rate (1μmh−1). The Bi content is ...found to vary proportionally with Bi flux with Bi contents, as measured by Rutherford backscattering, in the range 0<x≤4.5%. The GaSbBi samples grown at the lowest Bi fluxes have smooth surfaces free of metallic droplets. The higher Bi flux samples have surface Bi droplets. The room temperature band gap of the GaSbBi epitaxial layers determined from optical absorption decreases linearly with increasing Bi content with a reduction of ~32meV/%Bi.
•The incorporation of Bi in GaSb1−xBix alloys grown by molecular beam epitaxy is investigated as a function of Bi flux at fixed growth temperature.•The Bi content, measured by Rutherford backscattering, is found to vary proportionally with Bi flux.•The room temperature band gap of the GaSbBi epitaxial layers determined from optical absorption decreases linearly with increasing Bi content with a reduction of ~32 meV/%Bi.
Ga(In)SbBi alloys grown by molecular-beam epitaxy on GaSb substrates with up to 5.5% In and 1.8% Bi were studied by temperature- and power-dependent photoluminescence (PL) and compared to previous ...photoreflectance (PR) results. High energy and low energy PL peaks were observed and attributed respectively to Ga(In)SbBi bandgap-related emission and native acceptor-related emission. For GaSbBi below 100 K, the HE peak is at slightly lower energy than the bandgap determined from PR, indicating carrier localization. This phenomenon is significantly weaker in PL of GaInSbBi alloys, suggesting that the presence of indium improves the optical quality over that of GaSbBi.
The temperature dependence of the band gap of GaNxSb1−x films with has been studied in the 1.1-3.3 m (0.35-1.1 eV) range using infrared absorption spectroscopy between 4.2 and 300 K. As with other ...dilute nitride semiconductors, the temperature dependence of the band gap is reduced by alloying with nitrogen when compared to the host binary compound. However, for GaNSb, the smallest variation of the band gap with temperature is observed for samples with the lowest N content for which the band gap is almost totally insensitive to temperature changes. This contrasts with the more widely studied GaNxAs1−x alloys in which the band gap variation with temperature decreases with increasing N content. The temperature-dependent absorption spectra are simulated within the so-called band anticrossing model of the interaction between the extended conduction band states of the GaSb and the localized states associated with the N atoms. The N next-nearest neighbor pair states are found to be responsible for the temperature insensitivity of the band gap of the GaNSb alloys as a result of their proximity to the conduction band edge giving them a more pronounced role than in GaNAs alloys.
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