A robust interface enabled by electrospun membrane with optimal resistance in lithium metal batteries

A uniform diffusion layer is essential for non-dendritic deposition of lithium in high-density lithium batteries.However,natural pristine solid electrolyte interface(SEI)is always porous and inhomogeneous because of repeated breakdown and repair cycles,whereas ideal materials with excellent mechanical property for artificial SEIs remain a challenge.Herein,a robust and stable interface is achieved by spinning soft polymer associated with few MoO₃ into fibers,and thus mechanical property of fibers other than materials determines mechanical performance of the interface which can be optimized by adjusting parameters.Furthermore,lithium deposited underneath the layer is enabled by constructing an optimal resistance to make the membrane serve as an artificial SEI rather than lithium host.As a result,dendritefree lithium was observed underneath the membrane,and stable interface for long-term cycling was also indicated by EIS measurements.The lithium iron phosphate(LiFePO₄)full-cell with coated electrode demonstrated an initial capacity of 155.2 m Ah g^-1,and 80%of its original capacity was retained after 500 cycles at 2.0℃ without any additive in carbonate-based electrolyte.     

New insight into the stability and dynamics of fluid-conveying supported pipes with small geometric imperfections

In several previous studies, it was reported that a supported pipe with small geometric imperfections would lose stability when the internal flow velocity became sufficiently high. Recently, however, it has become clear that this conclusion may be at best incomplete. A reevaluation of the problem is undertaken here by essentially considering the flow-induced static deformation of a pipe. With the aid of the absolute nodal coordinate formulation(ANCF) and the extended Lagrange equations for dynam...     

Study on the Distribution of Low Molecular Weight Metabolites in Mango Fruit by Air Flow-Assisted Ionization Mass Spectrometry Imaging

Mass spectrometry imaging is a novel molecular imaging technique that has been developing rapidly in recent years. Air flow-assisted ionization mass spectrometry imaging (AFAI-MSI) has received wide attention in the biomedical field because of its features such as not needing a pretreatment sample, having high sensitivity, and wide coverage of metabolite detection. In this study, we set up a mass spectrometry imaging method for analyzing low molecular metabolites in mango fruits by the AFAI-MSI method. Compounds such as organic acids, vitamin C, and phenols were detected from mango tissue by mass spectrometry under the negative ion scanning mode, and their spatial distribution was analyzed. As a result, all the target compounds showed different distributions. Citric acid was mainly distributed in the pulp. Malic acid, quinic acid, and vitamin C universally existed in the pulp and peel. However, galloylglucose isomer and 5-galloylquinic acid were predominantly found in the peel. These results show that AFAI-MSI can be used for the analysis of mango fruit endogenous metabolites conveniently and directly, which will facilitate the rapid identification and in situ characterization of plant endogenous substances.     

VIBRATION AND STABILITY OF VERTICAL UPWARD-FLUID-CONVEYING PIPE IMMERSED IN RIGID CYLINDRICAL CHANNEL

A theoretical model is developed for the vibration and stability of a vertical pipe subjected concurrently to two dependent axial flows. The external fluid, after exiting the outer annular region between the pipe and a rigid cylindrical channel, is conveyed upwards inside the pipe. This configuration thus resembles of a pipe that aspirating fluid. The equation of planar mo- tion is solved by means of the differential quadrature method （DQM）. Calculations are conducted for a slender drill-string-like and a bench-top-size system, for different confinement conditions of the outer annular channel. It is shown that the vibrations of these two systems are closely related to the degree of confinement of the outer annular channel. For a drill-string-like system with narrow annuli, buckling instability may occur in the second and third modes. For a bench-top-size system, however, both buckling and flutter may occur in the lowest three modes. The form of instability depends on the annuli size.     

含非线性能量汇的简支输液管非线性振动控制研究

论文建立了一个含有非线性能量汇(NES)装置并输运脉动内流的简支输液管道理论模型,研究了NES装置对管道的非线性动力学特性与振动控制的影响.利用Galerkin和龙格库塔法,得到了在含NES和不含NES装置时管道动力学响应的数值结果.研究表明,NES装置能有效地抑制管道振动.通过对比可知,NES对管道系统的稳定性和非线性振动控制有着明显的影响.此外,论文还详细讨论了NES装置相关参数对系统的动力学影响.结果表明,增大NES的弹簧刚度k、阻尼σ和质量比e有利于管道减振,且最佳安装位置在管道中点.此外,增大阻尼σ能缩小失稳激励频率区域,而其他参数的变化对失稳激励频率区域影响较小.     

基于小波边缘提取的灰度图象联合相关识别预处理

本文将小波变换方法用于灰度图象的联合变换相关识别中,采用不同的尺度因子对输入图象进行边缘提取预处理,使相关识别结果得到不同程度的改善.通过计算机模拟对比了一阶、二阶微商的边缘提取方法和小波变换边缘提取方法的预处理结果和对识别的影响,在同时衡量相关识别能力及其对噪音的敏感性前提下,小波变换边缘提取预处理明显优于各种微商边缘提取方法.调节小波变换尺度因子还能使识别能力与噪音敏感性这两方面得到更好地均衡,使小波变换边缘提取预处理能够适应不同的图象输入条件和相关输出要求.结果表明,在联合变换相关识别中采用小波变换对输入图象进行预处理是一种更理想的方法。     

Magnetically Recoverable Core–Shell Nanocomposites with Enhanced Photocatalytic Activity

Core–shell structured Fe₃O₄/SiO₂/TiO₂ nanocomposites with enhanced photocatalytic activity that are capable of fast magnetic separation have been successfully synthesized by combining two steps of a sol–gel process with calcination. The as‐obtained core–shell structure is composed of a central magnetite core with a strong response to external fields, an interlayer of SiO₂, and an outer layer of TiO₂ nanocrystals with a tunable average size. The convenient control over the size and crystallinity of the TiO₂ nanocatalysts makes it possible to achieve higher photocatalytic efficiency than that of commercial photocatalyst Degussa P25. The photocatalytic activity increases as the thickness of the TiO₂ nanocrystal shell decreases. The presence of SiO₂ interlayer helps to enhance the photocatalytic efficiency of the TiO₂ nanocrystal shell as well as the chemical and thermal stability of Fe₃O₄ core. In addition, the TiO₂ nanocrystals strongly adhere to the magnetic supports through covalent bonds. We demonstrate that this photocatalyst can be easily recycled by applying an external magnetic field while maintaining their photocatalytic activity during at least eighteen cycles of use.     

Surface and fluorescence properties of a novel fluorescent surfactant

A novel kind of fluorescent surfactant having 7-hydroxylcoumarin group in the long alkyl chain was synthesized. The critical micelle concentration (CMC), surface tension (γ_cmc) at CMC and absorption, fluorescence properties of this product were determined. From the variations of fluorescence spectra in different solvents, it is observed that the polarity and dielectric constant of the solvents play important roles in the maximum fluorescence intensity and wavelength. Moreover, the surprised exhibition of two fluorescence bands in neutral and alkaline solutions has been attributed to the superexciplex formation of the product molecules. Also, the lower product concentration measuring the fluorescence properties as well as the supposed configuration of hydrogen bond of the product indicate that the larger aggregations cannot exist in alkaline solutions. The superexciplex is a possibility with two or more polar excited molecules together to form an excited state association.     

Single-mode low-loss chalcogenide glass waveguides for the mid-infrared

We demonstrate the design, fabrication, and characterization of single-mode low-loss waveguides for mid-infrared (MIR) wavelengths. Planar waveguide structures were fabricated from multilayer thin films of arsenic-based chalcogenide glasses followed by the creation of channel waveguides by using the photodarkening effect. Propagation losses as low as 0.5 dB/cm were measured for a quantum cascade laser end-fire coupled into the waveguides. This is a first step toward the design and fabrication of integrated optical components for MIR applications.