Anisotropic Superconducting Properties of Kagome Metal CsV_3Sb_5

We systematically measure the superconducting(SC) and mixed state properties of high-quality CsV_3 Sb_5 single crystals with T_c～3.5 K.We find that the upper critical field H_(c2)(T) exhibits a large anisotropic ratio of H_(c2)~(ab)/H_(c2)~c～9 at zero temperature and fitting its temperature dependence requires a minimum two-band effective model.Moreover,the ratio of the lower critical field,H_(c1)~(ab)/H_(c1)~c,is also found to be larger than 1,which indicates that the in-plane energy dispersion is strongly renormalized near Fermi energy.Both H_(c1)(T) and SC diamagnetic signal are found to change little initially below T_c～3.5 K and then to increase abruptly upon cooling to a characteristic temperature of ～2.8 K.Furthermore,we identify a two-fold anisotropy of in-plane angular-dependent magnetoresistance in the mixed state.Interestingly,we find that,below the same characteristic T～2.8 K,the orientation of this two-fold anisotropy displays a peculiar twist by an angle of 60° characteristic of the Kagome geometry.Our results suggest an intriguing superconducting state emerging in the complex environment of Kagome lattice,which,at least,is partially driven by electron-electron correlation.     

不同型线离心风机叶轮的性能对比研究

本文分别对采用常规单圆弧叶片和等减速叶片两种不同型线叶轮的离心风机进行了试验研究,并做了整机全工况数值模拟计算.流场分析表明:应用等减速流型设计的离心风机,其叶轮内部的流动损失小,压力梯度变化更规律,叶轮出口的射流-尾迹结构较弱,出口速度场均匀且最大速度值较低.所以,等减速流型设计的叶轮,其流动损失、扩压损失、出口混合损失以及出口截面突变损失均比较小,效率较高.     

流动注射停流-催化光度法测定环境水样中痕量Mn(Ⅱ)的研究

在碱性介质中,Mn(Ⅱ)对催化KIO4氧化镁试剂Ⅰ(对硝基苯偶氮间苯二酚)的褪色反应有显著作用。据此建立了测定痕量Mn(Ⅱ)的流动注射停流-催化光度法。优化了流动注射条件,Mn(Ⅱ)在2~10μg/L,10~160μg/L,160~1000μg/L范围内符合比尔定律,采样频率6样/h,检出限0.12μg/L,相对标准偏差(RSD)4.9%(n=6)。用于环境水样中Mn(Ⅱ)的检测,回收率为95.5%~102%。     

Promote the conductivity of solid polymer electrolyte at room temperature by constructing a dual range ionic conduction path

Poly(ethylene oxide)(PEO) is a classic matrix model for solid polymer electrolyte which can not only dissociate lithium-ions(Li+),but also can conduct Li+through segmental motion in long-range.However,the crystal aggregation state of PEO restricts the conduction of Li⁺ especially at room temperature.In this work,an amorphous polymer electrolyte with ethylene oxide(EO) and propylene oxide(PO) block structure(B-PEG@DMC) synthesized by the transesterification is firstly obtained,showing ...     

双间隙输出腔开放腔的高频特性分析

 建立了S波段相对论速调管放大器双间隙输出腔开放腔的3维模型。采用时域有限差分法,通过监测激励电流源的响应计算了该双间隙输出腔的谐振频率、有载Q值、场分布以及特性阻抗,并分析了腔体结构尺寸对谐振频率、有载Q值和特性阻抗的影响。研究表明：腔体半径对开放腔的谐振频率影响很大,耦合孔尺寸对腔体谐振频率的影响较小;随着耦合孔张角增加,有载Q值逐渐减小;随着腔体半径增大、间隙的减小,腔体特性阻抗降低。研究结果可为S波段强流相对论速调管放大器双间隙输出腔的设计提供理论依据。     

Benzamides Substituted with Quinoline-Linked 1,2,4-Oxadiazole: Synthesis,Biological Activity and Toxicity to Zebrafish Embryo

To develop new compounds with high activity, broad spectrum and low-toxicity, 17 benzamides substituted with quinoline-linked 1,2,4-oxadiazole were designed using the splicing principle of active substructures and were synthesized. The biological activities were evaluated against 10 fungi, indicating that some of the synthetic compounds showed excellent fungicidal activities. For example, at 50 mg/L, the inhibitory activity of 13p (3-Cl-4-Cl substituted, 86.1%) against Sclerotinia sclerotiorum was superior to that of quinoxyfen (77.8%), and the inhibitory activity of 13f (3-CF₃ substituted, 77.8%) was comparable to that of quinoxyfen. The fungicidal activities of 13f and 13p to Sclerotinia sclerotiorum were better than that of quinoxyfen (14.19 mg/L), with EC₅₀ of 6.67 mg/L and 5.17 mg/L, respectively. Furthermore, the acute toxicity of 13p was 19.42 mg/L, classifying it as a low-toxic compound.     

ON THE EXISTENCE WITH EXPONENTIAL DECAY AND THE BLOW-UP OF SOLUTIONS FOR COUPLED SYSTEMS OF SEMI-LINEAR CORNER-DEGENERATE PARABOLIC EQUATIONS WITH SINGULAR POTENTIALS

In this article,we study the initial boundary value problem of coupled semi-linear degenerate parabolic equations with a singular potential term on manifolds with corner singularities.Firstly,we introduce the corner type weighted p-Sobolev spaces and the weighted corner type Sobolev inequality,the Poincare′inequality,and the Hardy inequality.Then,by using the potential well method and the inequality mentioned above,we obtain an existence theorem of global solutions with exponential decay and show the blow-up in finite time of solutions for both cases with low initial energy and critical initial energy.Significantly,the relation between the above two phenomena is derived as a sharp condition.Moreover,we show that the global existence also holds for the case of a potential well family.     

外力驱动下耦合弹簧振子的法诺共振

法诺共振是物理体系中普遍存在的一种非对称共振现象,它最早起源于量子物理,其微观图像是原子谱线中窄的分离态与宽的连续态之间的相干干涉.本文利用经典力学体系中两个弹簧振子的耦合,使其中一个弹簧振子受到周期性外力的驱动,成功类比了量子力学中的法诺共振现象.通过分析每个弹簧振子的动力学方程,严格求解它们的振动公式,从而得到每个...     

用于长城等古建筑探测的NMR探测器的磁体设计

以万里长城为代表的古建筑是世界瑰宝,更是中华民族的象征和骄傲.本文提出利用便携式核磁共振（NMR）装置来探测研究这类古建筑的建筑材料,在不对其造成损伤的基础上,发掘其隐含的科学、技术和工程相关的丰富信息.为此,作为第一步,设计了适合于探测这类古建筑的便携式单边NMR探测器组合式磁体.该探测器的磁体结构以semi-Halbach为基础,通过不同磁体模块间的组合得到对应移动探测模式、长距离探测模式和均匀磁场探测模式的磁体结构.随后根据优化结果,设计加工了磁体组件,并采用该磁体进行了流体、长城城砖和现代红砖的NMR实验,实测结果与模拟一致.该组合式磁体的优点在于通过不同磁体模块组合,实现了多种探测方式,适用于探测长城等这类古建筑物需要多种探测模式的科学研究.