摘要：锂硫电池因理论能量密度高、生产成本低和环境友好等优点被认为是最有前途的下一代电化学储能装置之一。然而,硫和硫化锂的低导电性、严重的穿梭效应和缓慢的反应动力学等问题阻碍了锂硫电池的大规模商业化应用。炭材料因高比表面积,良好导电性与结构多样性而备受关注,然而非极性炭材料难以与极性多硫化物紧密结合,导致活性材料大量损失和严重的穿梭效应。金属氧化物具有极性强和丰富吸附位点的优点,将过渡金属氧化物与炭材料结合,有助于增强对多硫化物的化学吸附和电化学反应活性。本文首先介绍了锂硫电池的基本原理和存在的主要问题,然后讨论了近年来过渡金属氧化物/炭复合材料在合成方法和结构设计(1D,2D,3D)方面的研究进展。此外,详细介绍了异质结构设计、空位工程和晶面调控策略的代表性工作并讨论了其机理。最后,对过渡金属氧化物/炭复合材料用于锂硫电池中的发展进行了总结和展望。

摘要：开发可见光活化的纯有机室温磷光(room-temperature phosphorescence,RTP)材料已引起广泛关注。通过将基于菲咯啉的供体-受体(donor-acceptor,D-A)荧光粉掺入刚性聚合物基质聚乙烯醇(polyvinyl alcohol,PVA)中,开发了一种可见光激活的RTP设计策略。富含杂原子N的菲咯啉可促进三重态激子的产生,并与PVA形成丰富的氢键,抑制非辐射弛豫,从而引发磷光。在420 nm可见光照射下,通过调节分子共轭结构和D-A相互作用,掺杂荧光粉的PVA薄膜的磷光颜色可从绿色变为黄色。基于上述磷光特性,该薄膜可用于信息加密。该研究为在信息加密、传感器等领域制备具有良好应用前景的可见光活化磷光材料提供了一种简单可行的方法。

摘要：In order to monitor deformation of high temperature components for a long time,a sensing device integrating a bridge-shaped mechanical displacement amplifier has been *** sensing device has higher resolution and accuracy than conventional ***,the relation between the magnification ratio and the structure size of the displacement amplifier is a bottleneck of sensing device *** this,the magnification ratio of a mechanical displacement amplifier is analytically derived based on its geometry *** prototypes of the displacement amplifier made in propathene are manufactured,and an experimental system is set up to validate the accuracy of the established magnification ratio *** magnification ratios and experimental magnification ratios are compared and agree well,which verifies that the proposed equation is *** analytical equation provides an effective design method for bridge-shaped mechanical displacement amplifiers with an expected magnification ratio.

摘要：Broadband sound sink/absorber via a structure with deep sub-wavelength thickness is of great and continuing interest in physics and engineering *** intuitive technique extensively used is to combine components(resonators)with quasi-perfect absorption to piece together a broad absorbing band,but the requirement of quasi-perfect absorption substantially places a very strict restriction on the impedance and thickness of the ***,we theoretically and experimentally demonstrate that a compact broadband acoustic sink that quasi-perfectly absorbs broadband arriving sound waves can be achieved with coherently coupled‘‘weak resonances"(resonant sound absorbing systems with low absorption peaks).Although each component exhibits rather low absorption peak alone,via manipulating the coherent coupling effect among the components,they collectively provide a remarkably improved performance over a wide frequency range with a significantly compressed *** illustrate the design principle,a hybrid metasurface utilizing the coaction of parallel and cascade couplings is presented,which possesses an average absorption coefficient of 0.957 in the quasi-perfect band(a>0:9)from 870 to 3224 Hz with a thickness of only 3.9 *** results open new avenues for the development of novel and highly efficient acoustic absorbers against low frequency noise,and more essentially,suggest an efficient approach towards on-demand acoustic impedance engineering in broadband.

摘要：In this study,a high impact resistant multi-layered composite consisting of continuous carbon fibre/nylon(CCF)and short carbon fibre/nylon(SCF)layers is developed via 3D printing *** effect of CCF/SCF layers configuration on the impact resistance is investigated by low-velocity impact test,and the impact failure mechanism of the 3D printed composites is explored by microscopic observations and finite element(FE)simulation *** results show that the 3D printed multi-layered composite with SCF layers distributed in the middle(HFA)exhibits higher impact resistant performance than the specimens with alternating SCF/CCF layers(HFB)and CCF layers distributed in the middle(HFC).The effect of CCF/SCF layers proportion on the impact performance is also studied by FE simulation,and the results show that the specimen with a CCF/SCF proportion of 7.0 exhibits the highest impact strength.

摘要：An EMU train with detailed cabin structural is established based on the finite element *** secondary impact between train driver and control desk is fully analysed and two measures are proposed to reduce the driver injury severity,such as the multi-objective optimization of the driver seat position and equipping the train with three-point seat *** results indicate that the driver seat position has a significant effect on the driver injury severity during a secondary *** to the multi-objective optimization,some Pareto solutions are suggested to design the driver seat *** that,it is also indicated although the chest and leg are well protected when the driver wears a two-point seat belt,it increases the head injure during a secondary *** the other hand,the three-point seat belt can supply the train driver with an overall protection against the secondary *** injury criteria(HIC,VC,TI)of the driver with the three-point seat belt is significantly lower than those of the driver without seat ***,according to the simulation analysis,the limited load of the three-point seat belt is suggested about 1.5 kN.

摘要：The design and construction of highly effective circularly polarized luminescence(CPL)-active materials has aroused considerable attention due to their widespread applications in sensors,optical devices,and asymmetric ***,the exploration of novel CPL-active materials with high luminescence dissymmetry factor(glum)values is still a ***,we describe a new approach for the preparation of supramolecular metallacycles with amplified CPL promoted by hierarchical self-assembly involving Pt···Pt ***,the resultant metallacycles exhibited strong CPL signals with high glum values,while their corresponding precursors were CPL *** CPL amplification mechanism was comprehensively validated by ultravioletvisible absorption,emission spectroscopy,nuclear magnetic resonance spectroscopy,scanning electron microscopy,transmission electron microscopy,atomic force microscopy,coarse-grained molecular dynamics simulations,and timedependent density functional theory *** work thus provides the first example of preparing highly effective CPL-active materials based on hierarchical self-assembly involving Pt···Pt interactions.

摘要：Hollow metal-organic frameworks(MOFs)and their derivatives have attracted more and more attention due to their high specific surface area and perfect morphological structure,which determine their large potential application in energy storage and catalysis ***,few researchers have carried out further modification on the outer shell of hollow MOFs,such as the perforation modification,which will endow hollow nanomaterials derived from MOFs with *** this paper,hollow MOFs of MIL-53(Fe)with perforated outer surface are successfully synthesized by using SiO2 nanospheres as the template via a self-assembly process induced by the coordination *** tightly packed mesopore structure makes the carbon outer shell of MOFs thinner,thus realizing the in-situ transformation from MOFs to hollow Fe3 O4/carbon,which exhibits perfect capacity approaching 1270 mA h g-1 even after 200 cycles at 0.1 A g-1,as an anode material in lithium ion batteries(LIBs)*** research provides a new strategy for the design and preparation of MOFs and their derivatives with multifunctionality for the energy applications.

摘要：Objective:Pediatric cancer patients endure multiple symptoms during treatment and also in *** health technologies provide an innovative way to support their symptom *** review aimed to examine the effect of digital health technologies on managing symptoms among across pediatric cancer ***:A systematic literature search of six English and three Chinese electronic databases was combined with hand searching,to identify eligible research studies from database establishment to November 30,*** reviewers carried out data selection,data extraction,and quality appraisal independently.A narrative approach was taken to summarize ***:Four randomized control trials,two quasi-experiments,and five one group pre-posttest designed studies,were included in the review with a total of 425 *** methodological quality of the studies was generally *** symptoms(anxiety,depression,pain,anger,fatigue,fear,distress)and seven digital health technologies(visual reality,website,humanoid robot,app,wearable devices,short messages and videoconference)were reported in the included ***:Current evidence supports the effect of digital health technologies is generally mixed and *** is a trend of positive effects found in the interventions that feature digital health technologies’interactive *** review highlights the need for further investigation with rigorous research designs and the consideration of influencing factors from the symptoms,participants,and context levels to inform a better digital health implementation.

摘要：车速离散性是影响城市快速路运行效率与安全的重要特征指标.本文采用上海车牌识别系统采集的个体车速数据,使用车速方差作为特征指标,在随机基本图框架下对车速离散特征及其影响因素进行分析.通过比较发现,个体车速方差较集计车速方差数值偏大,整体稳定于5~15 km/h;随密度增大而小幅下降,可分为稳定型、递减型、抛物线型和集群型4类.通过建立多元线性回归模型辨识了车速离散的主要影响因素,包括车道数和匝道类型等.本文拓展了交通流基本图理论,对提升城市快速路安全和效率有借鉴意义.