Growth and characterization of superconducting Ca1-xNaxFe2As2 single crystals by NaAs-flux method

High-quality superconducting Ca$_{1-x}$Na$_x$Fe$_2$As$_2$ single crystals have been successfully grown by the NaAs-flux method, with sodium doping level $x = 0.4$-0.64. The typical sizes of these crystals are more than 10 mm in $ab$-plane and $\sim 0.1$ mm along $c$-axis in thickness. X-ray diffraction, resistance and magnetization measurements are carried out to characterize the quality of these crystals. While no signature of magnetic phase transitions is detected in the normal state, bulk superconductivity is found for these samples, with a sharp transition at $T_{\rm c}$ ranging from 19.8 K ($x = 0.4$) to 34.8 K ($x = 0.64$). The doping dependences of the $c$-axis parameter and $T_{\rm c}$ are consistent with previous reports, suggesting a possible connection between the lattice parameters and superconductivity.     

荜茇宁与邻硝基苯基荧光酮的荷移反应及其测定

建立了一种测定荜茇宁的方便快捷的荷移分光光度法。荜茇宁和邻硝基苯基荧光酮在中性三酸缓冲液中发生电荷转移反应,荷移络合物在515 nm处有最大吸收,表观摩尔吸光系数为6.571×10⁴ L·mol^-1·cm^-1。该络合物的组成是1:1,药物质量浓度在0.054 6~10.92 μg/mL范围内服从比尔定律,检出限为0.015 3 μg/mL。对反应机理进行了初步探索,并利用本方法对生物样品中的荜茇宁进行了加标回收,回收率为99.8%~100.9%,相对标准偏差(RSD)为0.90%。     

Cell image recognition with radial harmonic Fourier moments

Various types of moments have been utilized to recognize image patterns in a number of applications. Multi-distortion invariant－radial harmonic Fourier moments were investigated in the recognition of cell smear images. Image recognition experiments showed that radial harmonic Fourier moments are not only highly concentrated image features but also have a good property of antidistortion and antinoise. They may be used in fast and accurate automatic cell recognition.     

9-(3，5-二溴)水杨基荧光酮-溴化十六烷基三甲铵荧光光度法测定微量铝

研究了９－（３,５－二溴）水杨基荧光酮与铝（Ⅲ）的反应条件。在ＰＨ５．５的（ＣＨ２）６Ｎ４－ＨＣＬ缓冲溶液中,ＡＩ（Ⅲ）与试睡成络合物使试剂的荧光猝灭。建立了铝－９－（３,５－二溴）,水杨基荧光酮体系测定痕量铝的荧光光度法。荧光强度与铝的含量在０～１．４μｇ／ｍＬ范围内呈线性关系。本法已用于合金风标样中铝的测定。     

双向视ICP-OES法同时测定褐煤中锗和一些主要成灰元素

描述了ICP-OES(高频电感耦合等离子体光学发射光谱)同时测定褐煤中Ge和一些主要成灰元素Fe,Al,Ca,Mg,K,Na,Ti的方法。所使用的仪器是一台安装有双向视等离子体炬管和一个同时检测器的ICP光谱仪,这种技术允许分别在侧视和端视方式下同时测定主成分和微量元素。作者选取了适宜的仪器工作条件、选择了无干扰的分析谱线和合理地扣除了光谱背景,样品灰化后用HNO₃/HF/HClO₄混合酸消解,测定结果与国标方法吻合。仪器的检出限为0.000 39～0.10 μg·mL-1,方法的精密度RSD为0.79%～2.84%,样品平均回收率为92.38%。建立的方法可简便、快速、准确地对褐煤中锗及其他多种元素同时进行测定。     

黄芪中黄酮类组分的高效液相色谱分离条件的快速优化

以黄芪为研究对象,对黄芪中乙酸乙酯部位的化学成分进行了高效液相色谱分析并对其色谱操作条件进行了快速优化。根据几个线性梯度下的保留时间来计算各组分的保留参数,然后利用重叠分辨图法确定其最佳分析条件。在选定的最佳条件下各组分分离情况良好。利用梯度保留时间计算保留参数比较方便快速,并可以有效地避免以往等度线性回归法遇到的峰识别问题。该方法更适用于实际复杂样品色谱分析条件的优化。     

Simulation of Anisotropic Resistivity for Mixed-Phase Manganite La2／3Ca1／3MnO3 Thin Films

We utilize the random network model based on phase separation scenario to simulate the conductive behaviour and anisotropic characteristics of resistivity for La2/3Ca1/3MnO3 (LCMO) thin films. The simulated results agree well with our experimental data, showing a metal-to-insulator transition from a high-T paramagnetic (PM) insulating phase to a low-T ferromagnetic (FM) metallic phase in both the untilted film deposited on a (001) SrTiO3 (STO) substrate and the tilted film grown on a vicinal cut STO substrate. It is found that the resistivity of the tilted sample is higher than that of the untilted one, displaying prominent anisotropic characteristics. The studies reveal that the tilting not only decreases the conduction of the FM domains, but also increases the activation energy of the PM regions, inducing the enhancement of resistivity. All those results suggest that the intrinsic inhomogeneity in the phase separation system plays a significant role in the electrical conductivity and the resistive anisotropy is related to the structure of the crystal lattice.     

重离子碰撞中产生的K介子的末态作用

推广了RVUU模型,计入了K介子的平均场势和K与核子的末态重散射.并用它模拟了每核子1GeV入射能量的两个Ca核碰撞的阈下K⁺产生.讨论了K⁺矢量势和K⁺末态重散射效应对K介子的末态性质的影响.计算结果表明,排斥的矢量势,与K⁺的末态重散射相似,明显地影响了末态K⁺动能谱,导致了实验室系中具有大动量的K⁺产额的增大.然而,排斥的K⁺矢量势的计入可观地减少了K⁺的末态重散射的影响.这说明,为了合理地评价K⁺能谱和角分布,K⁺同核子的这些末态作用都是不能忽略的.     

Hamilton算子和R3中相似运动

四元数是一个可除环·　它可表达为R3中通过原点的平面中的四元数乘积的域·　利用Hamilton算子,定义了在该平面上的相似运动,并讨论了这些运动的新特性·     

Si1-xGex/Si量子阱价带子带间跃迁的偏振特性及Kerr效应的研究

首先用Fourier红外吸收谱对p型掺杂的Si_0.75Ge_0.25/Si量子阱价带子带间跃迁的偏振特性进行了研究。实验表明TE和TM偏振光均能激发价带子带间跃迁,并在HH₁→HH₂跃迁中观察到很强的二向色性。同时分别在45°及垂直入射的情况下,对加有直流电场的样品进行Fourier红外电致吸收测量,首次得到样品在不同直流电场下吸收系数变化谱和折射率变化的电场依赖关系(Kerr效应)。在外电场作用下测得的较大△n(∝E²)及子带间跃迁的偏振特性表明,SiGe/Si半导体量子阱材料在焦平面阵式布列的集成线路及光电器件等应用方面具有潜在优势。