摘要：An orthogonal experiment scheme was designed to investigate the effects of the Cu content,compaction pressure,and sintering temperature on the microstructures and mechanical and thermal properties of(30−50)wt.%Cu/Invar bi-metal matrix composites fabricated via spark plasma sintering(SPS).The results indicated that as the Cu content increased from 30 to 50 wt.%,a continuous Cu network gradually appeared,and the density,thermal conductivity(TC)and coefficient of thermal expansion of the composites noticeably increased,but the tensile strength *** increase in the sintering temperature promoted the Cu/Invar interface diffusion,leading to a reduction in the TC but an enhancement in the tensile strength of the *** compaction pressure comprehensively affected the thermal properties of the *** 50wt.%Cu/Invar composite sintered at 700℃ and 60 MPa had the highest TC(90.7 W/(m·K)),which was significantly higher than the TCs obtained for most of the previously reported Cu/Invar composites.

摘要：Extremely small-sized iron oxide nanoparticles(ESIONPs)with sizes less than 5 nm have shown great promise as T_(1)contrast agents for magnetic resonance imaging(MRI).However,their facile and scalable production with simultaneously endowed biocompatible surface chemistry remains difficult to be *** this study,by using the coprecipitation method implemented in a specially designed gas/liquid mixed phase fluidic reactor,polyglucose sorbitol carboxymethyether(PSC)coated ESIONPs were continuously synthesized with controllable particle sizes ranging from 1.8 to 4 *** the differently sized ESIONPs,the 3.7-nm ESIONPs exhibit the best performance as T_(1)MRI contrast agent,featuring a high r_(1) value of 4.11(mmol L^(−1))^(−1)s^(−1)and low r_(2)/r_(1) ratio of 7.90 under a clinical 3 T MR scanning,as well as the excellent T_(1)MRI contrast effect in not only water but also the cellular environment and blood ***,the ESIONPs possess long-term stability and good dispersity in aqueous dispersions,making them ideal candidates as safe and effective T_(1)-weighted MRI contrast agent for real clinical use.

摘要：Developing efficient electrocatalysts for the oxygen evolution reaction(OER)under neutral conditions is important for microbial electrolysis cells(MECs).However,the OER kinetics in neutral electrolytes at present are extremely sluggish,resulting in high overpotentials that greatly limit the energy conversion efficiencies of *** studies failed to probe the adsorbates on surface metal sites of catalysts at the atomic scale and elucidate their influence on the catalytic activities,which has impeded the rational design of efficient neutral OER catalysts with optimal surface ***,using in situ transmission electron microscopy(TEM),in situ X-ray photoelectron spectroscopy(XPS)and in situ low-energy ion scattering studies,we have identified,for the first time,that the electrochemically activated adsorbates on surface metal sites play a critical role in boosting the neutral OER activities of Ru-Ir binary oxide(RuxIryO2)*** adsorbate-activated RuxIryO2on a glassy carbon electrode achieved a low overpotential of 324 m V at10 m A cm-2in neutral electrolyte,with a 36-fold improvement in turnover frequency compared with that of Ir *** application in an MEC system,the resulting full cell showed a decreased voltage of 1.8 V,200 m V lower than the best value reported to date,facilitating efficient synthesis of poly(3-hydroxybutyrate)from bioelectrochemical *** functional theory(DFT)studies revealed that the enhanced OER activity of RuxIryO2catalyst arose from local structural distortion of adjacent adsorbate-covered Ru octahedra at the catalyst surface and the consequently decreased adsorption energies of OER intermediates on Ir active center.

摘要：三维(3D)狄拉克半金属因其独特的拓扑能带结构及优异的光电性能在中/远红外波段的宽光谱光电探测领域具有巨大的应用潜力.然而,由于较大的暗电流,构建具有高信噪比(SNR)的3D狄拉克半金属宽光谱光电探测器仍面临很大挑战.本工作基于分子束外延生长的(Cd_(1-x)Zn_(x))_(3)As_(2)薄膜发展了一种超低器件噪声的3 D狄拉克半金属(Cd_(1-x)Zn_(x))_(3)As_(2)/Sb_(2)Se_(3)背靠背异质结光电探测器线阵.得益于有效的双异质结设计策略,该探测器可以实现从可见光(450 nm)到中红外(4.5μm)波段的室温高性能宽光谱探测器目标,其峰值SNR和D*分别可达104和5.2×10^(12)Jones,并具有相对较快的响应速度(~87.5μs).此外,不同探测器线列单元之间呈现出的稳定性、均匀性特征表明了其在未来应用于光迹实时跟踪等光电子器件中的可行性.该研究为基于3D狄拉克半金属材料制备具有超高SNR的高速宽光谱光电探测器提供了参考策略,展示了半金属在高速非制冷红外焦平面成像阵列探测器中的广阔前景.

摘要：Aqueous Zn-iodine(Zn-I_(2))batteries have attracted extensive research interest as an emerging redox conversion energy storage system due to the low cost and high ***,the shuttling effects of polyiodides arising from incomplete redox conversion and inhomogeneous Zn plating on the Zn anode surface always hinder the commercial application of Zn-I_(2)*** this work,a two-birds-with-one-stone strategy is reported for long-life Zn-I_(2)*** on the strategy,the sulfonate-functionalized carbon fiber not only acts as the excellent iodine limiter to inhibit iodine species shuttling,but also as the uniform Zn plating guidance layer on the Zn anode surface to prevent the inhomogeneous deposition of Zn^(2+).Consequently,a superior cycling stability(a capacity of 124 mAh g^(-1)after 10,000 cycles at 5 A g^(-1))is *** calculations illustrate that sulfonate groups successfully induce charge redistribution on the carbon substrate,thereby strengthening the electronic interactions of the iodine species with the carbon *** charge-enriched sulfonate groups can guide the uniform deposition of Zn^(2+)through a strong Coulombic effect with Zn^(2+).This work gives a new perspective on the integrated design of cathodes and anodes for rechargeable batteries.

摘要：This study presents an innovative approach to improving the performance of YOLO-v8 model for small object detection in radar ***,a local histogram equalization technique was applied to the original images,resulting in a notable enhancement in both contrast and detail ***,the YOLO-v8 backbone network was augmented by incorporating convolutional kernels based on a multidimensional attention mechanism and a parallel processing strategy,which facilitated more effective feature information *** the model’s head,an upsampling layer was added,along with the fusion of outputs from the shallow network,and a detection head specifically tailored for small object detection,thereby further improving ***,the loss function was modified to incorporate focal-intersection over union(IoU)in conjunction with scaled-IoU,which enhanced the model’s performance.A weighting strategy was also introduced,effectively improving detection accuracy for small *** results demonstrate that the customized model outperforms traditional approaches across various evaluation metrics,including recall,precision,F1-score,and the receiver operating characteristic(ROC)curve,validating its efficacy and innovation in small object detection within radar *** results indicate a substantial improvement in accuracy compared to conventional methods such as image segmentation and standard convolutional neural networks.

摘要：无人机对地面目标的自主检测是智能巡航中至关重要的问题。近年来随着深度学习的崛起,卷积神经网络被尝试应用在目标识别领域。论文应用深度可分离的卷积结构设计了适用于无人机行人小目标检测的轻量卷积神经网络模型。使用无人机实拍样本在NVIDIA1080ti平台进行验证,处理速度可达到82帧/秒。