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The use of Constant‐stress accelerated degradation tests (CSADT) modeling is an effective way to assess the reliability of products. However, when conducting reliability experiments, the data collected may come from various sources such as different manufacturing batches, equipment, and operators. This can result in reduced accuracy of the test evaluations. In this research paper, we propose optimal designs for the Wiener constant‐stress accelerated degradation model that take into account the heterogeneity of manufacturing batches and individual differences. Our goal is to minimize the variability of the mean time to failure (MTTF) while working within a specified budget, test time, and available test units. To achieve this, we utilize particle swarm optimization (PSO) to find the best solution based on a complex objective function. We also compare our model with others using degradation data from LEDs, showing that our model has a better goodness‐of‐fit. Finally, we present examples of optimal CSADT plans under different constraints and conduct sensitivity analysis. [ABSTRACT FROM AUTHOR]

Blue-emissive nanocrystals (NCs) with high photoluminescence quantum yields (PL QYs) and excellent stability are essential for lighting and displays. Here, a facile top-down approach (including two steps: thermal annealing and ultrasonic treatment) by using aluminum acetylacetonate (Al(acac)3) as a precursor is adopted to fabricate blue-emissive Al(acac)3 NCs with high PL QY reaching 81.8%, the highest reported value for the aluminum compound-based NCs so far. Additionally, the as-fabricated Al(acac)3 NC solution (in toluene) exhibits high stability under air atmosphere condition, maintaining 61.2% of initial PL QY after 1 year. Furthermore, solution-processed Al(acac)3 NCs/poly(methyl methacrylate) (PMMA) composite film with blue emission is demonstrated. Finally, combinations of the blue-emitting Al(acac)3 NCs/PMMA composite film with red-emitting and green-emitting CuInS2 composite films are realized, resulting in remote ultraviolet-pumped white light-emitting diodes with a high color rendering index of 91. These findings inform new blue-emissive NCs and composite films, potentially paving the way to design new structures of lighting and display devices.

The unique advantages of perovskites make them excellent candidates for high performance nonlinear optical devices. However, the toxicity of Pb ions restricts their further applications. The realization of Pb-free or Pb-less perovskites is an important strategy to reduce the toxicity of Pb ions. Here, we substitute the Pb ions in perovskites with Zn ions and Bi ions. Zn-doped MAPbBr3 and Bi-doped MAPbBr3 with varying doping concentrations were synthesized. UV-visible absorption, X-ray diffraction and X-ray photoelectron spectroscopy patterns were utilized to verify the successful metal ion doping. Utilizing the Z-scan technique, the nonlinear absorption, nonlinear refraction, and optical limiting properties of MAPbBr3 before and after doping were studied. The results revealed an improvement in these properties following the doping process. Four-level models were put forward to elucidate the underlying mechanisms, which may be related to the changes in the type of defects after metal ion doping. This work promotes the applications of Pb-less perovskites in nonlinear optics. [ABSTRACT FROM AUTHOR]

Low‐dimensional organic–inorganic metal halides (OIMHs) have emerged as promising light emitters due to their broadband emission originating from self‐trapped excitons (STE), especially for Cu‐based OIMHs. Herein, Cu(I)‐based OIMH with a structure of (TPP)2Cu4I6·2DMSO (TPP stays for tetraphenylphosphonium, and DMSO – for dimethyl sulfoxide) has been synthesized, both in form of single crystals and as a microcrystalline powder. This compound exhibits a broadband green emission with a peak at 515 nm and a full width at half‐maximum of 78 nm, and a near‐unity photoluminescence quantum yield of 99.5%. Experimental data supported by theoretical calculations indicate that the STE emission is responsible for the green emission with a long lifetime of 2.53 µs. Down‐conversion light‐emitting device with a high luminous efficiency of 50 lm W−1 based on this compound have been fabricated, and white light has also been achieved with a high color rendering index of 96.7. Moreover, green emissive (TPP)2Cu4I6·2DMSO is utilized in scintillators for X‐ray detection and imaging, and as a luminescent ink for encryption applications. [ABSTRACT FROM AUTHOR]

Considering the influence of performance degradation on a product's traumatic failure, under the condition that only degradation data are observed and no traumatic failure data are observed, this paper proposes a subdistribution competing risk model to achieve a motorized spindle life assessment. This paper assumes that the failure rate ratio of the tested products does not change with time under different stress levels. Basic reliability with zero traumatic failure data is modeled by a unilateral confidence limit method under a two-parameter Weibull distribution. Performance degradation data are taken as covariates. The regression coefficients of the covariates are calculated by SPSS software. Then, a subdistribution competing risk model is constructed, which reflects the dependency relationship between reliability and performance degradation, and the product's reliability life can be evaluated accordingly. The correctness and advantages of the model built in this paper are verified by a case analysis combined with the performance degradation information of a motorized spindle. [ABSTRACT FROM AUTHOR]

The spinal cord has a poor ability to regenerate after an injury, which may be due to cell loss, cyst formation, inflammation, and scarring. A promising approach to treating a spinal cord injury (SCI) is the use of biomaterials. We have developed a novel hydrogel scaffold fabricated from oligo(poly(ethylene glycol) fumarate) (OPF) as a 0.08 mm thick sheet containing polymer ridges and a cell-attractive surface on the other side. When the cells are cultured on OPF via chemical patterning, the cells attach, align, and deposit ECM along the direction of the pattern. Animals implanted with the rolled scaffold sheets had greater hindlimb recovery compared to that of the multichannel scaffold control, which is likely due to the greater number of axons growing across it. The immune cell number (microglia or hemopoietic cells: 50–120 cells/mm2 in all conditions), scarring (5–10% in all conditions), and ECM deposits (Laminin or Fibronectin: approximately 10–20% in all conditions) were equal in all conditions. Overall, the results suggest that the scaffold sheets promote axon outgrowth that can be guided across the scaffold, thereby promoting hindlimb recovery. This study provides a hydrogel scaffold construct that can be used in vitro for cell characterization or in vivo for future neuroprosthetics, devices, or cell and ECM delivery. [ABSTRACT FROM AUTHOR]