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Lighting accounts for one-fifth of global electricity consumption.sup.1. Single materials with efficient and stable white-light emission are ideal for lighting applications, but photon emission covering the entire visible spectrum is difficult to achieve using a single material. Metal halide perovskites have outstanding emission properties.sup.2,3; however, the best-performing materials of this type contain lead and have unsatisfactory stability. Here we report a lead-free double perovskite that exhibits efficient and stable white-light emission via self-trapped excitons that originate from the Jahn-Teller distortion of the AgCl.sub.6 octahedron in the excited state. By alloying sodium cations into Cs.sub.2AgInCl.sub.6, we break the dark transition (the inversion-symmetry-induced parity-forbidden transition) by manipulating the parity of the wavefunction of the self-trapped exciton and reduce the electronic dimensionality of the semiconductor.sup.4. This leads to an increase in photoluminescence efficiency by three orders of magnitude compared to pure Cs.sub.2AgInCl.sub.6. The optimally alloyed Cs.sub.2(Ag.sub.0.60Na.sub.0.40)InCl.sub.6 with 0.04 per cent bismuth doping emits warm-white light with 86 [plus or minus] 5 per cent quantum efficiency and works for over 1,000 hours. We anticipate that these results will stimulate research on single-emitter-based white-light-emitting phosphors and diodes for next-generation lighting and display technologies.After alloying with metal cations, a lead-free halide double perovskite shows stable performance and remarkably efficient white-light emission, with possible applications in lighting and display technologies., Author(s): Jiajun Luo [sup.1] , Xiaoming Wang [sup.2] , Shunran Li [sup.1] , Jing Liu [sup.1] , Yueming Guo [sup.3] , Guangda Niu [sup.1] , Li Yao [sup.1] , Yuhao [...]

Purpose: This study aims to evaluate (1) the probability to achieve normal pelvic radiographs in children with developmental dysplasia of the hip (DDH) treated by closed reduction and (2) the amount of time needed to achieve normal pelvic radiographs and to assess what factors influence both probability and time to achieve normal radiographic parameters following CR and spica cast immobilization for DDH.Methods: We retrospectively reviewed 436 patients (393 girls, 43 boys; 507 hips) with DDH treated by closed reduction (CR). Tönnis grade, AVN, acetabular index (AI), centre-edge angle (CEA), and Severin radiographic grade were evaluated on plain radiographs. Criteria to rate pelvis radiographs as normal were established. Cox regression was used to evaluate the factors influencing the probability and the time to achieve normal radiographs.Results: According to our criteria, 167 hips (32.9%) achieved normal radiographic parameters during follow-up. The overall amount of time to achieve normal pelvis radiographs was 36.1 ± 15.5 months. Patients older than 24 months of age at the time of CR needed longer time to achieve normal radiographic parameters (55.2 ± 28 months) compared with other age groups. Cox regression analysis suggested the overall cumulative probability of recovery increased by 46% at five years following CR, then it tended to plateau with an annual increase less than 5%. Age older than 24 months, bilateral dislocation, pre-operative AI greater than 40°, and AVN were risk factors for reduced probability of achieving normal radiographic parameters.Conclusions: The cumulative probability of achieving normal pelvis radiographs increases linearly during the first five years following CR, then it tends to plateau. Age older than 24 months and Tönnis grade III and IV are associated with longer time to achieve normal radiographic parameters. Age older than 24 months, bilateral dislocation, pre-operative AI greater than 40°, and AVN are risk factors for reduced probability of achieving normal radiographic parameters in children with DDH treated by closed means. [ABSTRACT FROM AUTHOR]

Little is known about why and how biomechanics govern the hypothesis that three-Lag-Screw (3LS) fixation is a preferred therapeutic technique. A series models of surgical internal-fixation for femoral neck fractures of Pauwells-II will be constructed by an innovative approach of finite element so as to determine the most stable fixation by comparison of their biomechanical performance. Seventeen sets of CT scanned femora were imported onto Mimics extracting 3D models; these specimens were transferred to Geomagic Studio for a simulative osteotomy and kyrtograph; then, they underwent UG to fit simulative solid models; three sorts of internal fixators were expressed virtually by Pro-Engineer. Processed by Hypermesh, all compartments were assembled onto three systems actually as "Dynamic hip screw (DHS), 3LS and DHS+LS". Eventually, numerical models of Finite Elemental Analysis (FEA) were exported to AnSys for solution. Three models for fixtures of Pauwells-II were established, validated and analyzed with the following findings: Femoral-shaft stress for c (3LS) is the least; Internal-fixator stress (MPa) for a (DHS) = 1 9 6. 9 7 > b (DHS + LS) = 8 8. 3 7 > c (3 LS) = 6 3. 8 1 ; Integral stress (MPa) for a (DHS) = 1 9 5. 3 5 > b (DHS + LS) = 8 6. 7 2 > c (3 LS) = 6 4. 6 0 ; displacement of femoral head (mm) for a (DHS) = 1. 0 6 8 > c (3 LS) = 1. 0 1 0 > b (DHS+LS) = 0.735; displacement of femoral shaft (mm) for c (3 LS) = 0. 7 1 4 > a (DHS) = 0. 5 3 3 > b (DHS+LS) = 0. 4 7 5 ; and displacement of fixators for c (3 LS) = 0. 9 8 2 > a (DHS) = 0. 9 7 3 > b (DHS + LS) = 0. 7 0 6. Mechanical comparisons for other femoral parks are insignificantly different, and these data can be abstracted as follows: the stress of 3LS-system was checked to be the least, and an interfragmentary displacement of DHS+LS assemblages was assessed to be the least". A 3LS-system should be recommended to clinically optimize a Pauwells-II facture; if treated by this therapeutic fixation, breakage of fixators or secondary fracture is supposed to occur rarely. The strength of this study is that it was performed by a computer-aided simulation, allowing for design of a preoperative strategy that could provide acute correction and decrease procedure time, without harming to humans or animals. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the correlation between avascular necrosis (AVN) and the amount (severity) and direction (translation and angulation) of initial displacement of pediatric femoral neck fractures.Methods: We retrospectively reviewed 108 pediatric patients (mean age 10.3 ± 4.1 years) with femoral neck fractures. The amount of initial translation (T) and angulation (A) was measured on anteroposterior (AP; TAP% and AAP) and lateral (TL% and AL) radiographs. The direction of translation was determined on AP (medial or lateral) and lateral radiographs (anterior or posterior). Furthermore, the presence of a comminuted medial cortex on the AP pelvis radiograph was also recorded. Logistic regression analysis, receiver operating characteristic (ROC) curve analysis, student's t tests, and chi-square tests were used to evaluate the correlation between AVN and the severity and direction of displacement.Results: Twenty-eight out of 108 hips (25.9%) developed AVN of the femoral head. Logistical regression analysis indicated that TAP%, TL%, AAP, and AL were risk factors for AVN (P < 0.05). The analysis of ROC curves found that TAP% over 37.4% and TL% over 29% were the cut-off values for an increased incidence of AVN; similarly, AAP over 8° and AL over 18.6° were the cut-off values for an increased incidence of AVN. The amount of initial translation is a better predictor of AVN than angulation is; fractures with posterior translation (P = 0.002) and/or medial comminution had a significantly higher incidence of AVN (P = 0.005). The mean diagnostic accuracy of translation (74-75%) was significantly higher than that of angulation (65-66%).Conclusions: Displacement severity and direction are important radiological parameters to be assessed in children with femoral neck fractures. Initial translation better predicts AVN than angulation does. Posterior translation and medial comminution are associated with an increased risk of AVN. [ABSTRACT FROM AUTHOR]