AlN ceramics are widely used in power electronics packaging due to their excellent thermal conductivity. In order to prepare AlN ceramics with good mechanical properties and thermal conductivity, 0-3 wt% Si3N4 was dop...
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AlN ceramics are widely used in power electronics packaging due to their excellent thermal conductivity. In order to prepare AlN ceramics with good mechanical properties and thermal conductivity, 0-3 wt% Si3N4 was doped and annealed at 1600 degrees C. The effects of Si3N4 doping and annealing on the microstructure, thermal conductivity, and mechanical properties of the fabricated AlN ceramics were investigated. The study demonstrated that the incorporation of Si3N4 resulted in the generation of Y2Si3O3N4 and SiAl4O2N4, which not only refined the AlN grains but also enhanced the strength of the grain boundary phase, ultimately enhanced the hardness and fracture toughness of the ceramic samples. Furthermore, the annealing process facilitated AlN grain growth and improved the crystallinity of the grain boundary phase, which increased the thermal conductivity of the AlN ceramics. Notably, after the annealing process, 0.5 SiN samples exhibited a 37% increase in thermal conductivity, and a concurrent 30% increase in fracture toughness and a 23% increase in hardness, reaching 4.2 MPam(1/2) and 12.8 GPa, respectively. Finally, this study explores the mechanism of Si3N4 doping in order to modulate the properties of AlN ceramics by changing the liquid phase composition.
Due to the simple structure and strong anti-interference ability of pointer meters, they play a crucial role in complex industrial environments. To address the limitations of existing intelligent reading methods, whic...
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Due to the simple structure and strong anti-interference ability of pointer meters, they play a crucial role in complex industrial environments. To address the limitations of existing intelligent reading methods, which rely on prior knowledge of scale values, are not adaptable to various types of meters, involve difficulties in meter elements extraction, and are inefficient in reading processes, this paper proposes a human-like reading method for pointer meter based on scale values recognition and meter elements segmentation. Specifically, the YOLODIG algorithm is proposed for the identification of the primary scale values in the scale reading phase, thereby addressing the challenge of scale value a priori, which is applicable to a variety of pointer meters. In the subsequent stage of meter elements extraction, we propose the CL-Multi-U2Net multi-class semantic segmentation network to segment the pointer lines and primary scale lines. Our proposed cross-scale aggregation interaction module (CSAIM) effectively integrates multi-scale information across layers, increasing the penalty for edge contour segmentation by redesigning the loss function to improve the accuracy of meter elements segmentation. Of particular significance is the proposal of the human eye simulation reading method (HESRM) in the reading stage to calculate precise reading values. The HESRM has the advantage of effectively reducing cumulative error and improving reading efficiency and recognition accuracy. The experimental results demonstrate that the YOLODIG algorithm attains an SRM rate of 95.61. The mean Intersection over Union and F-1-score of the CL-Multi-U(2)Net meter elements segmentation network achieve 86.64 and 92.56, respectively, representing improvements of 0.67 and 0.38 compared to the pre-optimization phase. The HESRM proposed in this research attains an average reference error rate of only 0.245%, which is the lowest in comparison with existing methods and is more suitable for practic
Aqueous zinc ion batteries (AZIBs) have attracted much attention because of their environmental friendliness, high theoretical capacity and low cost. However, zinc metal anodes face challenges of zinc dendrite formati...
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Aqueous zinc ion batteries (AZIBs) have attracted much attention because of their environmental friendliness, high theoretical capacity and low cost. However, zinc metal anodes face challenges of zinc dendrite formation and by-product generation during electrochemical reactions. Herein, the non-toxic cyclic organic compound 1,4,7,10-tetraazecyclododecane (Cy) was utilized as an additive to optimize a ZnSO4 (ZS) electrolyte system, aiming to inhibit side reactions and dendrite growth on the zinc metal surface. Cy molecules could form coordination complexes with Zn2+ ions, thereby entering the solvated sheath of Zn2+ and reducing the activity of H2O molecules. In addition, the contact between the active molecules of H2O and the zinc metal anode was minimized, and hydrogen evolution potential was decreased as Cy adsorbed more preferentially to the surface of zinc metal than H2O, thus avoiding local alkaline enhancement and effectively inhibiting side reactions. After incorporating 10 g L-1 Cy into ZS electrolyte solution, a cycle life exceeding 4000 h was achieved for a Zn||Zn symmetric battery at 2 mA cm-2/1 mA h cm-2. Additionally, stable cycling performance over 3000 cycles with an average CE of 99.45% was attained for a Zn||Cu asymmetric battery in the modified electrolyte system. Moreover, for a Zn||VO2 full battery with the Cy-added ZS electrolyte, a capacity retention rate of 75.5% was obtained after 2000 cycles. This work proposes a high-efficiency electrolyte additive to suppress dendrite growth and side reactions on the surface of zinc metal by tailoring the solvated structure of Zn2+ and the interface between the Zn metal and the electrolyte.
Ammonia (NH3) is a promising carbon-free hydrogen carrier, but lowering the temperature required for its catalytic decomposition to produce H2 remains a challenge. The main obstacle is the strong adsorption of nitroge...
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Ammonia (NH3) is a promising carbon-free hydrogen carrier, but lowering the temperature required for its catalytic decomposition to produce H2 remains a challenge. The main obstacle is the strong adsorption of nitrogen (N) on the active sites, which can remain on the catalysts' surface and lead to poisoning. Using first-principles calculations, we investigate the effects of N accumulation on Fe6 clusters during NH3 decomposition and aim to develop strategies to mitigate N poisoning. Graphene-supported Fe6 clusters mitigate N poisoning by reducing Fe-N interaction strength, thereby improving NH3 decomposition efficiency. The energy barriers of the graphene-supported Fe6Nx (x = 1, 2) clusters' rate-limiting step have been reduced below 2 eV, compared to those calculated for the pure Fe6 cluster (2.08 eV) and the graphene-supported Fe6 cluster (2.53 eV). The rate-limiting step involves the Fe 3d-N 2p hybridization, during which an adsorbed N atom migrates across the Fe-Fe bond and combines with another N atom to form N2. This study provides new insights into the potential application of graphene-supported metal catalysts for NH3 decomposition.
Difficult airway management poses significant risks in anesthesia and emergency medicine, including hypoxemia and airway injury. While image-based methods have improved airway assessment, they often fail to capture fu...
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Difficult airway management poses significant risks in anesthesia and emergency medicine, including hypoxemia and airway injury. While image-based methods have improved airway assessment, they often fail to capture functional information like airway patency and vocal cord movement. To address this, we propose voice-assisted multimodal fusion network (VAMF-Net), which integrates three-view airway images with voice data to improve difficult airway evaluation accuracy. VAMF-Net employs an early fusion strategy of multi-view image features with contrastive learning pretraining, enabling early interaction between views to capture complementary information. Furthermore, We introduce a voice-assisted cross-attention module, which prioritizes image data as the primary source while using voice data as supplementary input. A dataset of 1,106 samples (89 difficult and 1017 easy cases) was constructed, with each sample including three airway images (frontal open mouth, frontal tongue extended, and side head tilted back) and voice data. VAMF-Net achieved an AUC of 0.917, sensitivity of 0.931, and specificity of 0.815, demonstrating superior performance compared to existing methods.
The unpredictable and extremely cold weather conditions, combined with increasing electromagnetic pollution, have posed a serious threat to human health and socioeconomic well-being. However, existing deicing technolo...
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The unpredictable and extremely cold weather conditions, combined with increasing electromagnetic pollution, have posed a serious threat to human health and socioeconomic well-being. However, existing deicing technologies and electromagnetic interference (EMI) materials lack adaptability to low-temperature, high-humidity environments. This study developed a lightweight asymmetric layered composite foam by integrating multilevel core-shell structures with heterogeneous core-shell fillers into a melamine foam (MF) matrix. Designed to leverage the differences in conductivity and dielectric constant between multiscale heterogeneous interfaces, this composite foam enhances the movement of free electrons and the relative displacement between electrons and atomic nuclei, thereby achieving efficient polarization and conduction losses. More than that, the unique feature of this composite lies in its '' absorption-absorption-reflection-reabsorption '' multilevel structure, enabling the composite to achieve an EMI shielding effectiveness of 70.7 dB in the X-band (8.2-12.4 GHz) and an absorption efficiency of 79.8%. Benefiting from the destructive interference of electromagnetic waves within the layered foam structure, the asymmetric composite foam (MHC-MNPF-ACN) exhibits superior absorption-dominated EMI shielding performance with excellent frequency selectivity. Additionally, by anchoring dual-size fillers onto the MF skeleton via impregnation adsorption to form a honeycomb-like 3D '' light-trapping '' network. This not only allows the composite foam to reach 93.6 degrees C under 1 sun, enabling rapid deicing within 160 s but also endows it with excellent superhydrophobicity and mechanical properties. These features provide a novel and multifunctional integrated approach to the fabrication of frequency-selective, absorption-dominated EMI shielding materials, proposing a new strategy for the protection of outdoor electromagnetic facilities in extremely low-temperature environm
Epoxy coatings with both self-cleaning and radiation protection functions have important application prospects in the nuclear industry. However, combining these two functions poses a significant challenge. To address ...
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Epoxy coatings with both self-cleaning and radiation protection functions have important application prospects in the nuclear industry. However, combining these two functions poses a significant challenge. To address this challenge, epoxy resin (EP) was modified with hydroxyl-terminated polydimethylsiloxane (PDMS) as the matrix. Additionally, 1H,1H,2H,2H-perfluorodecyltriethoxysilane hydrophobically modified micrometer-sized bismuth oxide (Bi2O3) was used as a functional filler. By adjusting the roughness with a small amount of hydrophobic silica (SiO2), a superhydrophobic self-cleaning coating with gamma radiation shielding capabilities was successfully developed. The resulting coating demonstrated exceptional self-cleaning properties, mechanical stability, and remarkable gamma-ray shielding in tests.
Heterogeneous-structured high-entropy alloys (HEAs) have successfully addressed the trade-off between strength and ductility, demonstrating significant potential across vehicle, aerospace and defense sectors. During s...
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Heterogeneous-structured high-entropy alloys (HEAs) have successfully addressed the trade-off between strength and ductility, demonstrating significant potential across vehicle, aerospace and defense sectors. During service, these alloys are invariably subjected to loading at varying strain rates. This manuscript investigates the deformation behavior of the heterogeneous-structured CrMnFeCoNi samples across strain rates spanning from 10-4 s-1 to 5 x 103 s-1. The strain rate sensitivity of the heterogeneous HEA (0.018) shows similarities to its homogeneous counterpart (0.017). With increasing strain rate from 10-4 s-1 to 5 x 103 s-1, fine-grained regions exhibit higher geometrically necessary dislocation (GND) density (from 1.44 x 1014 m-2 to 1.63 x 1014 m-2), contrasting with the constant density in coarse-grained regions (1.40 x 1014 m-2). At 5 x 103 s-1, the strain gradient between coarse and fine grains is more pronounced compared to that under quasi-static loading, resulting in enhanced hetero-deformation-induced strengthening. Additionally, regardless of the deformation region or strain rate, the log-normal function accurately describes local misorientation distributions.
The two-dimensional (2D) Z-scheme system is an effective approach for hydrogen production via photocatalytic water splitting (PWS). This study established a 2D van der Waals (vdW) SnC/Sc2CCl2 heterojunction for PWS. T...
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The two-dimensional (2D) Z-scheme system is an effective approach for hydrogen production via photocatalytic water splitting (PWS). This study established a 2D van der Waals (vdW) SnC/Sc2CCl2 heterojunction for PWS. The electronic and optical properties of the designed heterojunction were determined using first-principles methods, showing that the heterojunction, acting as a Z-scheme photocatalyst (ZSP), formed an induced internal electric field to achieve effective electron-hole separation. The strong redox ability (similar to 1.5 eV) and moderate energy barrier of the SnC/Sc2CCl2 heterojunction further enabled efficient PWS. Moreover, the PWS process benefited from the heterojunction's favorable absorption coefficient (105 cm-1) and solar-to-hydrogen conversion efficiency (21.36%) under visible light. The proposed Z-scheme SnC/Sc2CCl2 heterojunction is a promising candidate for photocatalytic overall water splitting (POWS) across a pH range of 0-14.
Iron-based spinel oxides, with excellent catalytic activity and stability, hold promising potential in the photo-Fenton degradation of organic pollutants. In this study, (Fe0.2Co0.2Ni0.2Cu0.2Mn0.2)Fe2O4 was prepared v...
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Iron-based spinel oxides, with excellent catalytic activity and stability, hold promising potential in the photo-Fenton degradation of organic pollutants. In this study, (Fe0.2Co0.2Ni0.2Cu0.2Mn0.2)Fe2O4 was prepared via the solution combustion method. Multiple characterization techniques confirmed the good stability and morphology of (Fe0.2Co0.2Ni0.2Cu0.2Mn0.2)Fe2O4. It exhibited high-entropy oxide properties, making it suitable as a photo-Fenton catalyst for the efficient degradation of oxytetracycline hydrochloride (OTC-HCl). Under visible light (Vis) with 10 mM H2O2, 0.06 g/L OTC-HCl, and pH 4.0, the catalyst achieved a degradation efficiency of 92.9%. In the photo-Fenton system, the utilization rate of H2O2 (calculated as the ratio of the degradation amount of OTC-HCl to the consumption amount of H2O2) was 34.5, which is 8.3 times higher than that of pure H2O2 (4.2). The catalyst showed good acid-base adaptability, achieving OTC-HCl removal rates exceeding 92.0% across a pH range of 3-11, with a reaction rate constant of 0.08 min(-1) at pH 11. Free-radical capture experiments showed that (Fe0.2Co0.2Ni0.2Cu0.2Mn0.2)Fe2O4 catalyzed H2O2 to generate OH, O-2(-), and e(-), which are the main free radicals involved in the degradation of OTC-HCl. In summary, (Fe0.2Co0.2Ni0.2Cu0.2Mn0.2)Fe2O4 not only addresses the issue of low H2O2 utilization in traditional photo-Fenton systems but also catalyzes the generation of H2O2 under light conditions. Thus, it can serve as an excellent photo-Fenton catalyst for OTC-HCl degradation.
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