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Objective The MS 6.8 earthquake that struck Luding County, Sichuan Province, on September 5, 2022, and its aftershocks have drawn widespread attention, especially concerning the potential risks of induced seismicity associated with the construction of high-dam reservoirs in regions with high seismic intensity. Previous studies have explored the possible link between reservoirs and seismic activity, without reaching a definitive conclusion. This study aims to assess the impact of water storage in the Dagangshan Reservoir on the surrounding strata and its correlation with recent seismic events. Methods Numerical simulation methods were employed using high-precision digital elevation model (DEM) data, fault data, and reservoir water level information to develop a three-dimensional poroelastic finite element numerical model extending from the surface to a depth of 25 km. By analyzing the hydrogeological conditions, lithology of rock masses, and groundwater dynamic changes, this study evaluated the seismic hazard risk of major faults, such as the Moxi Fault, and calculated variations in Coulomb stress and strata pore pressure at the hypocenter during the occurrence of the earthquake. Results The study indicates that, during the MS 6.8 Luding earthquake on September 5, 2022, the pore pressure at the epicenter reached 5 kPa, and the Coulomb stress increased by 3.6 kPa, suggesting that the impoundment of the Dagangshan Reservoir contributed to an increased risk along the Moxi Fault on the northwestern side of the reservoir. Using the source parameters of the MS 5.6 aftershock that occurred on January 26, 2023, it was observed that the impoundment caused a change in Coulomb stress at the epicenter of -0.69 kPa and a pore pressure of approximately 0.32 kPa. It is evident that the reservoir impoundment had a relatively minor impact on the fault activity where the MS 5.6 aftershock occurred and even exhibited a certain inhibitory effect. Moreover, seismic activity was mainly concentrated in two areas on the western side of the reservoir, with both the seismicity and expected magnitudes in these regions reflecting a higher risk of earthquakes. Conclusion This study demonstrates a correlation between the impoundment activities of the Dagangshan Reservoir and the occurrence of the Luding County earthquake and its aftershocks. The spatial distribution characteristics of the earthquakes align with the geological stress adjustment patterns following the reservoir impoundment, which played a promotive role in the occurrence of the MS 6.8 main shock, leading to an increased risk of earthquakes in the Moxi Fault region. This finding is significant for understanding the mechanisms of reservoir-induced earthquakes, subsequent aftershock analyses, and earthquake disaster prevention and mitigation efforts. Significance The results of this study provide new insights into the complex relationship between reservoir water storage and seismic events. This study offers a scientific basis for future assessments of seismic risks of reservoir design and operation, contributing to improved accuracy in earthquake early warnings and efficiency in disaster prevention and mitigation efforts.

The quantum confinement effect is an effective strategy to broaden the bandgaps of quasi-2D perovskites for achieving efficient blue perovskite light-emitting diodes (PeLEDs). However, reducing the quantum well (QW) width in quasi-2D PEA2Csn−1PbnBr3n+1 perovskites always induces a disordered QW distribution, which is detrimental to its electroluminescent performance. We disclose that low-n quasi-2D perovskites tend to freely distort octahedra forming γ-phase perovskites due to the lattice mismatch brought by small-size Cs+ ions. The short-chain ligand ethylammonium (EA) is then used to suppress the distortion of [PbBr6]4− octahedra by partially entering the A-site interspace as a larger cation. The quasi-2D perovskites prepared with the mixed EA/PEA ligands exhibit a narrow diffraction peak with little octahedral distortion, uniform QW distribution and efficient energy transfer process. The sky-blue PeLEDs prepared with the proposed strategy of mixed EA/PEA ligands achieve a remarkable external quantum efficiency of 14.14%. [ABSTRACT FROM AUTHOR]

The mechanisms governing electric field and partial discharge (PD) under stress cone dislocation remain unclear. This study employs the finite element method to explore the relationship between the electric field, externally applied voltage, and length of dislocation. Subsequently, the correlation between voltage and electric field is determined. The relationship between voltage and PD is established through PD tests conducted under stress cone dislocation conditions. By considering the influence of voltage, the association between the electric field and PD is established, revealing the mechanism of PD initiation by electric field distortion in joints. The findings suggest that the lifetime and reliability were increased by wrapping semi‐conductive self‐adhesive tape around the exposed cross‐linked polyethylene (XLPE) insulation layer. The electric field at a specific location is approximately proportional to the applied voltage. However, the slope is influenced by the composite insulation interface and the radial distance of the copper conductor. When crossing the interface between the XLPE insulation layer and the accessory insulation layer, the slope decreases significantly. The threshold for electric field PD is determined by examining the electric field distribution and the PD inception voltage during testing. When the voltage is sufficiently high, significant electric field distortions can occur at multiple points in the joint, potentially leading to concurrent PDs at several locations. [ABSTRACT FROM AUTHOR]

Mesoproterozoic (ca. 1.3 Ga) magmatism in the North China Craton (NCC) was dominated by mafic intrusions (dolerite sills) with lesser amounts of granitic magmatism, but our lack of knowledge of this magmatism hinders our understanding of the evolution of the NCC during this period. This study investigated porphyritic granites from the Huade–Kangbao area on the northern margin of the NCC. Zircon dating indicates the porphyritic granites were intruded during the Mesoproterozoic between 1285.4 ± 2.6 and 1278.6 ± 6.1 Ma. The granites have high silica contents (SiO2 = 63.10–73.73 wt.%), exhibit alkali enrichment (total alkalis = 7.71–8.79 wt.%), are peraluminous, and can be classified as weakly peraluminous A2-type granites. The granites have negative Eu anomalies (δEu = 0.14–0.44), enrichments in large-ion lithophile elements (LILEs; e.g., K, Rb, Th, and U), and depletions in high-field-strength elements (HFSEs; e.g., Nb, Ta, and Ti). εHf(t) values range from –6.43 to +2.41, with tDM2 ages of 1905–2462 Ma, suggesting the magmas were derived by partial melting of ancient crustal material. The geochronological and geochemical data, and regional geological features, indicate the Mesoproterozoic porphyritic granites from the northern margin of the NCC formed in an intraplate tectonic setting during continental extension and rifting, which represents the response of the NCC to the break-up of the Columbia supercontinent. [ABSTRACT FROM AUTHOR]

Although sensitizing traditional fluorescent dyes with thermally activated delayed fluorescence (TADF) exciplexes has been extensively studied, the device performance of solution‐processed organic light‐emitting diodes (OLEDs) still lags far behind in this regard. Herein, the novel exciplex with high up‐conversion efficiency composed of a triazatruxene‐based donor and a triazine‐based acceptor is employed as a TADF sensitizer to fluorescent dye in solution‐processed hyperfluorescent OLEDs. Benefiting from the small activation energy for triplet up‐conversion and less non‐radiative recombination of triplet excitons, the new TADF exciplex can up‐convert efficiently non‐radiative triplet excitons through reverse intersystem crossing. Besides, expeditious up‐conversion processes also shorten the residence time of triplet excitons, giving rise to significant suppression of detrimental Dexter energy transfer from the exciplex sensitizer to the dopant. By maximizing the triplet up‐conversion efficiency of exciplex sensitizers, the optimized OLEDs achieve a maximum external quantum efficiency (EQEmax) of 16.0%, which is the first report for the solution‐processed exciplex‐sensitized hyperfluorescent OLEDs with EQEmax exceeding 15%. These results validate that the up‐conversion efficiency of triplet excitons in the exciplexes strongly affects the performance of exciplex‐sensitized fluorescent devices, and the triazatruxene‐based molecules are promising donor candidates for constructing the exciplexes with high up‐conversion efficiency. [ABSTRACT FROM AUTHOR]

Phosphorescent manganese(II) complexes with high photoluminescence quantum yields (PLQYs) and low cost exhibit great potential in organic light‐emitting diodes (OLEDs), information security, and X‐ray imaging. However, it is still a challenge to tune their emission colors. Herein, an effective strategy for engineering the phosphorescence colors of tetrahedral Mn(II) complexes through steric hindrance‐driven bond angle distortion is proposed. Modulating the steric hindrance between phosphine and benzofuran and varying the O─Mn─O bond angles allows these Mn(II) complexes to emit from 498 to 548 nm. Interestingly, these achiral single crystals of Mn(II) complexes exhibit significant circularly polarized luminescence signals due to symmetry breaking. Furthermore, high‐performance green OLEDs are achieved by using these Mn(II) complexes as dopants, providing a record‐high external quantum efficiency of 15.7%. These super‐duper results greatly inspire the development of multi‐color Mn(II) complexes and low‐cost Mn‐based devices. [ABSTRACT FROM AUTHOR]

This study aimed to longitudinally observe the improvement mechanism of semantic fluency in subacute post-stroke aphasia (PSA) patients using resting-state functional magnetic resonance imaging (rs-fMRI). Twelve PSA patients, about one month after onset, were enrolled in this study and received speech-language therapy (SLT) for one month. Auditory comprehension and semantic fluency were evaluated using the Western Aphasia Battery (WAB) and the Animal Fluency Test. Before and after treatment, rs-fMRI data were collected, and the dice similarity coefficient was used to measure the spatial similarity between each patient's lesion and a reference lesion. The left posterior inferior temporal gyrus (pITG) was used as a seed to calculate the normalized functional connectivity in whole-brain voxel analysis using DPABI software for statistical analysis. The dice similarity coefficient between each patient's lesion and the reference lesion showed moderate to high intensity (0.57 ± 0.14) in the Montreal Neurological Institute space. After treatment, we found a significant increase in functional connectivity between the left pITG and the right prefrontal lobe convergence area (peak t = 8.219, Gaussian random field multiple comparison correction, voxel p < 0.001, cluster p < 0.05). The increase in functional connectivity was negatively correlated with the improvement in auditory comprehension (r =–0.707, p = 0.033) and positively correlated with the improvement in semantic fluency (r = 0.79, p = 0.02). The improvement of semantic fluency in subacute PSA patients may require the participation of the right convergence area of the prefrontal lobe. [ABSTRACT FROM AUTHOR]

Seafloor spreading is an important cornerstone of the theory of plate tectonics. Asymmetric seafloor spreading and oceanic ridge jumps are common phenomena in this process and play important roles in controlling oceanic crust accretion, regional tectonics and geological geometric boundaries. As the largest marginal sea in the western Pacific, the South China Sea is an ideal laboratory for dissecting the Wilson cycle of small marginal sea-type ocean basins restricted by surrounding blocks and exploring the deep dynamic processes of confined small ocean basins. In recent years, a lot of research has been conducted on the spreading history of the South China Sea and has achieved fruitful results. However, the detailed dynamic mechanisms of asymmetric seafloor spreading and ridge jumps are still unclear. Therefore, this paper summarizes the basic understanding about the dynamic mechanisms of global asymmetric seafloor spreading and ridge jumps and reviews the related research results of asymmetric seafloor spreading and ridge jumps in the South China Sea. Previous studies have basically confirmed that seafloor spreading in the South China Sea started between ~32 and 34 Ma in the east sub-basin and ended at ~15 Ma in the northwest sub-basin, with at least once oceanic ridge jump in the east sub-basin. The current research mainly focuses on the age of the seafloor spreading in the South China Sea and the location, time and stage of the ridge jumps, but there are relatively few studies on high-resolution lithospheric structure across these ridges and the dynamic mechanism of oceanic ridge jumps. Based on the current research progress, we propose that further studies should focus on the lithosphere–asthenosphere scale in the future, suggesting that marine magnetotelluric and Ocean Bottom Seismometer (OBS) surveys should be conducted across the residual oceanic ridges to perform a detailed analysis of the tectonics magmatism in the east sub-basin to gain insights into the dynamic mechanisms of oceanic ridge jumps and asymmetric seafloor spreading, which can promote understanding of the tectonic evolution of the South China Sea and improve the classical plate tectonics theory that was constructed based on the open ocean basins. [ABSTRACT FROM AUTHOR]

Distributed acoustic sensing incorporates multiple indicators, and there exists a mutually constraining relationship among these indicators. Different application fields have varying requirements for indicators. Therefore, indicator testing and comprehensive evaluations are crucial for engineering applications. In this paper, we conducted a theoretical analysis of key indicators, including frequency response, sensitivity, spatial resolution, sensing distance, multi-point perturbation, and temperature influence. The indicator test scheme was developed, and a test system was constructed. The test data were analyzed and compared in the time-frequency domain. A performance evaluation method for distributed acoustic sensing, based on the analytic hierarchy process, is proposed, and a comprehensive evaluation example focused on high-frequency applications is presented. The results show that the test scheme and method presented in this paper can accurately measure the upper limits of each indicator of distributed acoustic sensing. The proposed comprehensive evaluation method enables the assessment of sensor performance and applicability based on engineering practices. It addresses the challenge of evaluating distributed acoustic sensing with multiple indicators and offers an efficient approach for equipment development and engineering applications. [ABSTRACT FROM AUTHOR]