Calcium ion pinned vanadium oxide cathode for high-capacity and long-life aqueous rechargeable zinc-ion batteries

Science China Chemistry - Rechargeable aqueous zinc ion batteries (ZIBs), with the easy operation, cost effectiveness, and high safety, are emerging candidates for high-energy wearable/portable...     

Snap-through path in a bistable dielectric elastomer actuator

The dielectric elastomer (DE) has attracted significant attention due to its desired features, including large deformation, fast response, and high energy density. However, for a DE actuator (DEA) utilizing a snap-through deformation mode, most existing theoretical models fail to predict its deformation path. This paper develops a new finite element method (FEM) based on the three-parameter Gent-Gent model suitable for capturing strain-stiffening behaviors. The simulation results are verified by experiments, indicating that the FEM can accurately characterize the snap-through path of a DE. The method proposed in this paper provides theoretical guidance and inspiration for designing and applying DEs and bistable electroactive actuators.     

Effects of High-Intensity Ultrasound Pretreatment on Structure,Properties, and Enzymolysis of Walnut Protein Isolate

The purpose of this paper was to investigate the effect of high-intensity ultrasonication (HIU) pretreatment before enzymolysis on structural conformations of walnut protein isolate (WPI) and antioxidant activity of its hydrolysates. Aqueous WPI suspensions were subjected to ultrasonic processing at different power levels (600–2000 W) and times (5–30 min), and then changes in the particle size, zeta (ζ) potential, and structure of WPI were investigated, and antioxidant activity of its hydrolysates was determined. The particle size of the particles of aqueous WPI suspensions was decreased after ultrasound, indicating that sonication destroyed protein aggregates. The ζ-potential values of a protein solution significantly changed after sonication, demonstrating that the original dense structure of the protein was destroyed. Fourier transform infrared spectroscopy indicated a change in the secondary structure of WPI after sonication, with a decrease in β-turn and an increase in α-helix, β-sheet, and random coil content. Two absorption peaks of WPI were generated, and the fluorescence emission intensity of the proteins decreased after ultrasonic treatment, indicating that the changes in protein tertiary structure occurred. Moreover, the degree of hydrolysis and the antioxidant activity of the WPI hydrolysates increased after sonication. These results suggest that HIU pretreatment is a potential tool for improving the functional properties of walnut proteins.     

Co_2Fe(μ_3-S)(CO)_7(CH_3CSNH)的合成与结构

用Co2（CO）8与CH3CSNH2反应制得产物Ⅰ，又用Na2Fe（CO）4与Ⅰ反应制得产物Ⅱ（Ⅰ：Co3（μ3－S）（CO）7（CH3CSNH），Ⅱ：Co2Fe（μ3-S）（CO）7（CH3CSNH）．通过元素分析。IR、UV、1HNMR、MS表征并用X射线衍射法测得Ⅱ的单晶结构.该簇合物属三斜晶系、PT空间群，晶胞参数：a=0．9203（1），b=1．1296（2），c=1.1425（2）nm；α=116．40°（2），β＝101．92°（2），γ＝92．58°（1）；z＝2，V=1．2162nm3，Dc＝1．698cm3，μ＝21．89cm-1.结构分析表明，Co2FeS构三角锥分子骨架，所有CO均为端基配体，S1为面桥基配体，CH3CSNH为双齿配体，与Co、Fe形成五元环结构．     

离子选择电极阵列土壤中硝态氮测定

土壤硝态氮反映土壤短期氮素供应水平,实时了解土壤硝态氮的含量为精准农业和农业面源污染防控提供支撑,因此,在线实时检测土壤硝态氮方法突破就显得十分迫切。土壤硝态氮中的硝酸根离子在土壤中的高水溶性和流动性为全固态硝酸根离子选择电极高敏感检测土壤中硝态氮提供了条件,固态硝态氮离子选择电极的离子选择膜反应硝酸根离子在被测溶液中的浓度。采用全固态硝酸根离子选择电极,且与温度电极和pH电极融合组成电极阵列对土壤饱和溶液中的硝态根离子进行检测。设计了高输入阻抗运算放大电路对电极信号进行采集,并通过微处理控制蠕动泵完成土壤硝态氮待测溶液连续流动测量及实时传输结果。实验结果表明,电极响应时间≤15 s,斜率-51.63 mV/decade,线性范围10-5-10-2.2 mol/L,最低检测限10-5.23 mol/L。相对标准差在0.78%-4.47%范围内,加标回收率均在90%-110%以内。与国家标准紫外可见分光光度法测试结果相比,相关系数（R2）为0.9952,为土壤硝态氮在现场检测奠定技术基础。     

教、学、用三方对力学基本概念重要性认可度的调查研究

基础力学系列课程作为工科专业的技术性基础课程,如何适应和克服国家在本科教育教学方面提出的系列改革理念所突显的不足和矛盾,已成为课程组必须思考和面临的问题.基于课程改革的需要,该文采用问卷调查方式,进行了教、学、用三方对基础力学基本概念重要性认知程度的调查研究.结果发现:本科生人群对教学要求侧重点的把握不足;教师对课程体系要求和内容的理解上存在差异;显示了四川大学基础力学教学在基础教育与专业教育之间不同需求的矛盾.     

Fiber Bragg grating hydrophone with high sensitivity

A fiber Bragg grating （FBG） hydrophone with high sensitivity was demonstrated. This hydrophone used a rubber diaphragm and a copper hard core as the sensing element. To compensate the hydrostatic pressure, a capillary tube was fixed at the end of the hydrophone. Theoretical analysis of the acoustic pressure sensitivity was given in this letter. Experiments were carried out to test the frequency response of the hydrophone. The result shows that when the Young＇s modulus of the diaphragm is higher, a flatter frequency response will be obtained.     

LD泵浦Nd：BGO晶体的自调Q激光器

首次实现了ＬＫ泵浦Ｎｄ∶ＢＧＯ固体激光器的１．０６４μｍ的激光输出，泵浦阈值功率为２５ｍＷ，在连续运转状态下得到最大为４０ｍＷ的ＴＥＭ００模输出，光－光效率为１３．３％，根据法拉第磁光效庆理论，了ＬＤ泵浦Ｎｄ∶ＢＧＯ自调Ｑ激光器的各种参数，并研制成该激光器，在该器件中，作为损耗调制元件的磁光调制器就是绕有线圈的Ｎｄ∶ＢＧＯ晶体本身，实验在重复率为１ＫＨｚ的条件下得到了ＦＷＨＭ为１００ｎｓ的稳定脉冲     

热流计校准装置自适应温度控制方法研究

以热流计校准装置为研究对象,建立了热板温度仿真模型。根据模糊控制原理和BP神经网络原理,分别设计了模糊PID控制器和BP神经网络PID控制器,并在Matlab的Simulink下进行了不同控制方法的仿真对比实验。仿真结果表明:模糊PID有更快的响应速度、更短的稳定时间,BP神经网络PID有更小的超调量。     

压缩感知在合成发射孔径医学超声成像中的应用

为了解决合成发射孔径技术在医学超声成像实现中面临的数据量大及接收通道多的问题,提出一种超声成像系统频率域稀疏性模型的压缩感知成像算法。首先对超声系统频率域稀疏性模型进行了验证;然后根据稀疏性模型利用压缩感知理论对回波信号进行压缩采样,并使用最优化方法完成回波信号重建;最终通过合成发射孔径技术完成超声成像。针对医学成像中常用的点目标及模拟胎儿目标进行成像仿真实验,对重建图像在均方误差、分辨率及成像质量等方面与常规成像结果对比分析。实验结果表明在保证成像质量的同时,仅使用30%原始数据量及50%总接收通道数目可完成成像;频率域稀疏性模型的压缩感知成像算法可以大幅度减少合成发射孔径成像所需数据量及接收通道数,极大地降低了系统复杂度。