十二烷基苯磺酸钠增敏乙基紫共振光散射法测定人尿中痕量1-羟基芘

基于乙基紫(EV)与1-羟基芘(1-OHP)反应形成离子缔合物,导致体系的共振光散射(RLS)增强,建立了测定1-OHP的共振光散射法.在pH 8.0Tris-HCl缓冲介质中,最大RLS峰位于396 nm,其强度与1-OHP浓度成线性关系.加入表面活性剂十二烷基苯磺酸钠(SDBS),体系的灵敏度可提高两倍以上.方法的线性范围为4.0～982 μg·L-1,相关系数r=0.999 4,检出限1.2 μg·L-1,相对标准偏差为5.8%～7.9%,平均回收率为94%(n=6).已成功用于人尿中痕量1-OHP的测定,结果满意.     

二极管阵列检测-流动注射分光光度法同时测定食品中铁铜钴

目的在于建立同时测定食品中铁、铜、钴三种微量元素的新方法。以2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚(5-Br-PADAP)为显色剂,Triton X-100为增敏剂,采用流动注射-CCD二极管阵列检测-分光光度分析法同时对其进行测定。优化了实验参数,并用偏最小二乘法计算程序解析重叠光谱。结果显示,铁、铜和钴的线性范围分别为0.2～10 μg·mL-1,0.1～5.0 μg·mL-1,0.01～1.0 μg·mL-1,检出限分别为：0.2,0.1,0.01 μg·mL-1,进样频率为45样·h-1。所建方法用于茶叶、芝麻、小米等食品测定时,样品加标回收率分别为铁89.4%～102.3%、铜92.2%～108.0%、钴93.2%～110.8%,相对标准偏差为1.1%～12.1%。对国家一级标准参考物质茶叶和桃叶进行测定(ｎ＝8),结果在其给出的保证值范围之内。     

对超重、失重演示实验的改进

对传统的超重、失重演示实验进行了改进,使弹簧秤的指针能静止在超重(或失重)的位置上,从而能准确地读出读数,提高演示效果.     

多光束激光远场干涉实验研究

设计了多组多孔径光阑,将激光扩束后通过自制的多孔径光阑,获得多光束相干激光光源.基于多光束干涉理论,通过改变不同的光阑,得到多组点状阵列分布的远场干涉图样,结果表明远场中心主瓣具有随着占空比减小能量降低、旁瓣增多的分布规律.实验结果表明,相干源呈正三角形分布时能量集中度较好.对高功率激光相干合成具有一定的参考意义.     

Friction Properties of Bio-mimetic Nano-fibrillar Arrays

Nano-fibrillar arrays are fabricated using polystyrene materials. The average diameter of each fiber is about 300 nm. Experiments show that such a fibrillar surface possesses a relatively hydrophobie feature with a water contact angle of 142°. Nanoscale friction properties are mainly focused on. It is found that the friction force of polystyrene nano-fibrillar surfaces is obviously enhanced in contrast to polystyrene smooth surfaces. The apparent coefficient of friction increases with the applied load, but is independent of the scanning speed. An interesting observation is that the friction force increases almost linearly with the real contact area, which abides by the fundamental Bowden-Tabor law of nano-seale friction.     

Numerical study of homogeneous dynamo based on experimental von Kármán type flows

A numerical study of the magnetic induction equation has been performed on von Kármán type flows. These flows are generated by two co-axial counter-rotating propellers in cylindrical containers. Such devices are currently used in the von Kármán sodium (VKS) experiment designed to study dynamo action in an unconstrained flow. The mean velocity fields have been measured for different configurations and are introduced in a periodic cylindrical kinematic dynamo code. Depending on the driving configuration, on the poloidal to toroidal flow ratio and on the conductivity of boundaries, some flows are observed to sustain growing magnetic fields for magnetic Reynolds numbers accessible to a sodium experiment. The response of the flow to an external magnetic field has also been studied: The results are in excellent agreement with experimental results in the single propeller case but can differ in the two propellers case.     

西藏区域经济系统的灰色关联分析

区域经济的发展受许多不同因素的影响，本结合西藏社会经济发展的特点，选取了总产值指标、第一产业指标、第二产业指标和第三产业指标等四大类指标体系，采用灰色关联分析法对西藏的区域经济系统进行了简要的分析评价，以研究西藏区域经济的发展状况，从社会经济的角度探讨西藏经济发展落后的原因，以期能为西藏经济发展政策提供参考依据。     

The best quadrature formula based on Hermite information for the class KW~2[a,b]

The best quadrature formula has been found in the following sense:for afunction whose norm of the second derivative is bounded by a given constant and thebest quadrature formula for the approximate evaluation of integration of that function canminimize the worst possible error if the values of the function and its derivative at certainnodes are known.The best interpolation formula used to get the quadrature formula aboveis also found.Moreover,we compare the best quadrature formula with the open compoundcorrected trapezoidal formula by theoretical analysis and stochastic experiments.     

局域共振型声学超材料薄板带隙特性的能量解法

研究局域共振型声学超材料的带隙特性时,面临的首要问题是寻求一种带隙特性的高效解法。为此,本文以局域共振型声学超材料薄板为研究对象,提出了一种基于能量泛函变分原理及正交多项式级数展开的带隙计算方法。该方法通过合并基体板及共振子的动、势能及外力功建立元胞的能量泛函,经过变分运算得到元胞的振动控制方程,进而引入第一类Chebyshev正交多项式作为基函数将控制方程进行离散。为克服无法直接对离散控制方程中的广义坐标施加周期边界条件的困难,该方法将连续边界条件弱化到若干选定的配点上以离散方式实现,并将对应的一组线性约束条件通过拉格朗日乘子法施加到系统中。仿真结果表明,该方法具有较高的计算精度和效率,并可应用于\     

Er3+单掺、Er3+/Yb3+共掺杂Ca12Al14O32F2的 制备及上转换发光性质

利用高温固相法成功制备了Er~(3+)单掺、Er~(3+)/Yb~(3+)共掺杂Ca_(12)Al_(14)O_(32)F_2上转换发光样品。在980 nm激光激发下,Er~(3+)单掺和Er~(3+)/Yb~(3+)共掺杂样品均呈现出较强的绿光(528,549 nm)和较弱的红光(655 nm)发射,分别归因于Er~(3+)离子的~2H_(11/2),~4S_(3/2)→~4I_(15/2)和~4F_(9/2)→~4I_(15/2)能级跃迁。随着Er离子浓度的增加,单掺杂样品上转换发光强度先增大后减小,最佳掺杂浓度为0.8%。共掺杂Yb~(3+)后,Er~(3+)的发光强度明显增大。还原气氛下合成的样品上转换发光强度增大约两倍,可能和笼中阴离子基团变化有关。发光强度和激发光功率的关系表明所得上转换发射为双光子吸收过程,借助Er~(3+)-Yb~(3+)体系能级结构详细讨论了上转换发射的跃迁机制。