Colloidal thallium halide nanocrystals with reasonable luminescence, carrier mobility and diffusion length.

Colloidal lead halide based perovskite nanocrystals (NCs) have been recently established as an interesting class of defect-tolerant NCs with potential for superior optoelectronic applications. The electronic band structure of thallium halides (TlX, where X = Br and I) show a strong resemblance to lead halide perovskites, where both Pb2+ and Tl+ exhibit a 6s2 inert pair of electrons and strong spin-orbit coupling. Although the crystal structure of TlX is not perovskite, the similarities of its electronic structure with lead halide perovskites motivated us to prepare colloidal TlX NCs. These TlX NCs exhibit a wide bandgap (>2.5 eV or <500 nm) and the potential to exhibit a reduced density of deep defect states. Optical pump terahertz (THz) probe spectroscopy with excitation fluence in the range of 0.85-5.86 × 1013 photons per cm2 on NC films shows that the TlBr NCs possess high effective carrier mobility (∼220 to 329 cm2 V-1 s-1), long diffusion length (∼0.77 to 0.98 µm), and reasonably high photoluminescence efficiency (∼10%). This combination of properties is remarkable compared to other wide-bandgap (>2.5 eV) semiconductor NCs, which suggests a reduction in the deep-defect states in the TlX NCs. Furthermore, the ultrafast carrier dynamics and temperature-dependent reversible structural phase transition together with its influence on the optical properties of the TlX NCs are studied.

Sealing the acetabular notch in cemented total hip arthroplasty. A radiological review of 380 cases.

Recent in vitro work has shown that sealing the acetabular notch with bone graft in bovine acetabulum samples results in improved cement penetration in the acetabular bone during total hip arthroplasty. Successful sealing of the notch may be identified on postoperative films by a lack of cement extrusion. This study aimed to assess the clinical effectiveness of this technique in preventing cement escape and early radiolucent lines by review of early postoperative radiographs. We reviewed the post-operative radiographs of 380 consecutive patients who underwent primary total hip arthroplasty with implantation of the same flanged cemented polyethylene cup. The incidence, site and extent of cement extrusion and the incidence of any early postoperative radiolucent lines at the cement bone interface were measured. We found the rate of inferior cement escape in our series was 9.2%, compared to 36.4% in a previous study. We also found a lower rate of early radiolucent lines compared to historical controls. We believe placing bone graft on the medial/inferior wall prior to cementing helps to increase cement pressurisation by sealing the acetabular notch, as identified by reduced cement escape and early radiolucent lines.

Tibial-stem dissociation in a modular revision total knee arthroplasty system: a comparative clinical outcome study.

Stem dissociation in modular revision knee arthroplasty, due to failure of the frictional lock of the Morse taper, has previously been reported in the literature. The medium-term to long-term implications of stem dissociation are however unknown because the clinical outcomes have not been reported. We report a series of 10 cases of tibial-stem dissociation in the Coordinate revision knee system (DePuy, Warsaw, Ind). At an average follow-up of 8.1 years (range, 6-11 years), there was no detriment to the clinical outcome in 9 cases in which there was a contained bony defect. In one case in which there was a significant medial-tibial uncontained bony defect, there was a failure of the prosthesis, which necessitated re-revision arthroplasty surgery at 4 years. We therefore question whether long canal-filling tibial stems are necessary in all revision knee arthroplasties, particularly when there is a contained bone defect together with optimal alignment and adequate support of the prosthesis, and a non-constrained-polyethylene insert is used.