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Metal halide perovskites hold a great promise for the development of electroluminescent and down‐conversion light‐emitting diodes (LEDs) owing to their easily tunable optical bandgaps, high photoluminescence quantum yields (PLQYs) and excellent color purity. 3D structural perovskites, valued for their high charge carrier transport capacity, have garnered much attention for high‐performance electroluminescent LEDs with low operating voltages. However, solution‐processed 3D perovskite films always suffer from the generation of defect‐induced trap states on the surfaces and at the grain boundaries, resulting in nonradiative recombination that detracts from the electroluminescence performance. Herein, a 3D/2D heterostructure is constructed to reduce the surface defects of CsPbIxBr3‐x based 3D perovskites by reconfiguring the surface of the 3D perovskite film with fluorine para‐substituted phenethylammonium iodine (p‐FPEAI). The analysis of charge carrier dynamics indicates a decrease in trap‐assisted nonradiative recombination and a notable increase in radiative recombination in the red 3D/2D perovskite films. Consequently, the cutting‐edge deep‐red LEDs with the resultant 3D/2D heterostructure perovskite as the emissive layer demonstrate a high external quantum efficiency of 22.2% and a very stable electroluminescence peak at 674 nm. The proposed p‐FPEAI‐assisted surface engineering is considered a resultful approach for advancing the development of high‐performance LEDs with perovskite heterojunction. [ABSTRACT FROM AUTHOR]

Due to the hydrophobic organic cations, quasi‐two‐dimensional (quasi‐2D) lead halide perovskite materials have shown better moisture resistance. However, the inappropriate multiphase structure in the quasi‐2D perovskite films seriously affects the efficient transport of energy from low‐n domains to high‐n domains, especially when prepared in air. Herein, the study develops efficient quasi‐2D perovskite films in 30% ± 10% humidity and studies their amplified spontaneous emission (ASE) properties. It can be seen that the phase disproportionation of the quasi‐2D perovskite films prepared in air is greatly suppressed by manipulating the crystallization kinetics of the multiphase structure via using the organic additive benzimidazole (BI), thereby enabling a narrowed phase distribution. Due to the improvement in energy transfer efficiency, surface roughness, and humidity stability, the ASE with a low threshold of 13.4 µJ cm−2 is realized under the quasi‐continuous pumping condition, which is significantly <28.8 µJ cm−2 of the pristine film. Furthermore, the introduction of BI organic additive enhanced the number of peak intensity half‐decay pulses to as high as 5.6 × 107, indicating a good operating stability of the BI‐treated films. This work suggests that the BI‐treated quasi‐2D perovskite films provide the possibility for preparing high‐performance lasers in air. [ABSTRACT FROM AUTHOR]

Tectonically deformed coal (TDC) is closely related to gas outbursts. Since TDC exploration is an essential objective for coalfield exploration, it is of great significance to study the petrophysical properties of TDCs and explore their differences. This study collected 17 TDCs and undeformed coal samples from the Huaibei coalfield and ultrasonically tested their petrophysical parameters, including densities, P- and S-wave velocities, and their derived petrophysical parameters (VP/VS ratio, P- and S-wave impedances). Undeformed coal and TDCs with different deformation types (brittle, shear, and plastic deformations) show significant differences in their petrophysical parameters, and cross-plot analysis can directly differentiate them. As with traditional geological methods, acoustically measured petrophysical parameters are good indicators to determine the type of coal deformation. However, the TDCs with the same deformation type have similar petrophysical parameters; it is not easy to distinguish them directly. Instead, the proposed method incorporating principal component analysis and clustering can accurately distinguish up to five classes of TDCs. Different types of tectonic deformation environments and their intensities are highly correlated with the clustering results. This paper also provides essential petrophysical parameters for undeformed coal and TDCs in the Huaibei coalfield, and these parameters can help interpret undeformed coal and TDCs using wireline logs and seismic data. [ABSTRACT FROM AUTHOR]

Quasi-2D CsPbBr3 perovskites hold great potential as the promising emitters for perovskite light-emitting diodes (PeLEDs) owing to their good film morphology, excellent thermal stability and efficient radiative recombination. However, quasi-2D CsPbBr3 films are usually composed of multiple phases with various numbers (n) of [PbBr6]4− octahedral layers, and the formed n = 1 phase shows nonradiative recombination and retarded exciton transfer, which are detrimental to the performance of PeLEDs. Here, we report a facile approach to grow quasi-2D CsPbBr3/Cs4PbBr6 nanocomposite films as the emissive layers (EMLs) for efficient PeLEDs by simply introducing excess CsBr in the precursor solution. In the perovskite nanocomposite films, it is found that the formation of the n = 1 phase is completely suppressed and the density of trap states is dramatically lowered, leading to the significant reduction of nonradiative losses. In addition, the formed Cs4PbBr6 with a large bandgap can centralize carriers and confine excitons in quantum wells to realize efficient transfer, and can also constrain the crystal size and enhance the exciton binding energy of CsPbBr3, all of which facilitate the radiative recombination. As a result of the reduced nonradiative losses and improved radiative recombination, the green PeLED based on the quasi-2D CsPbBr3/Cs4PbBr6 nanocomposite EML achieves greatly enhanced performance with a maximum external quantum efficiency (EQE) of 11.84%, which is much higher than the maximum EQE of 1.94% of the quasi-2D CsPbBr3 device. This study demonstrates that the construction of perovskite nanocomposites should provide an effective way to promote the performance of PeLEDs. [ABSTRACT FROM AUTHOR]

Objective: To analyze the construction and effect of standardized procedure of early activity after cardiac surgery in elderly patients based on the critical illness scoring system., Methods: A total of 65 elderly patients who underwent cardiac surgery in our hospital from January 2020 to January 2022 were selected as the research objects and divided into the control group (n = 32) and the observation group (n = 33) according to the admission time. The standardized procedure for the early activity after cardiac surgery was implemented based on the critical illness scoring system. The inter-group comparison was conducted in terms of the recovery time, complications, cardiac function, and quality of life pre- and post-nursing., Results: The observation group recovered faster than the control group following nursing care. The incidence rate of complications was 6.06% in the observation group, noticeably lower than 25.00% in the control group. The observation group exhibited remarkably higher left ventricular ejection fraction (LVEF), noninvasive cardiac output (NICO), and stroke volume (SV) but lower left ventricular end-diastolic dimension (LVED) post-nursing than the control group, which indicated that the cardiac function index was superior in the observation group. Following the nursing, the observation group attained higher scores in each item of the World Health Organization Quality of Living Scale (WHOQOL-BREF) than the control group., Conclusion: The critical illness scoring system is of significant value in constructing a standardized process of early postoperative cardiac surgery in the elderly, which can effectively promote postoperative recovery, reduce the occurrence of complications, protect cardiac function, and improve the quality of life of patients affected.