光催化还原制备Au/Ag核壳结构纳米粒子及其修饰电极的电催化性能

以Keggin结构硅钨杂多酸H4SiW12O40(SiW12)为光催化还原剂,通过光化学还原法制备Au/Ag核壳结构纳米粒子. 透射电子显微镜分析显示,所得纳米粒子粒径为30～40 nm,呈均匀分散的球形颗粒,该制备方法的特点是可以较好的避免单金属纳米粒子的形成. 将Au/Ag核壳纳米粒子修饰到具有PVP膜的玻碳电极表面,得到SiW12-(Au/Ag)-PVP多层膜修饰电极. 该修饰电极在0.5 mol/L H2SO4介质中具有良好的电化学响应,在0～-0.75 V电位范围内,出现了3对归属于SiW12的氧化还原峰,且电极性能稳定,灵敏度高. 对H2O2的电催化还原性能明显优于单金属Ag纳米粒子修饰电极,说明Au核的存在可以很好的改善Ag的电催化性能,Au和Ag之间存在相互协同催化作用.     

中性微乳液介质增敏鲁米诺电化学发光研究

磷酸盐缓冲的中性溴化十六烷基三甲基铵-正戊醇-正庚烷微乳液介质体系对鲁米诺的电化学发光有显著的增敏作用，本文对此增敏作用进行了研究，并在此介质体系中采用电化学发光淬灭法测定了生物活性分子褪黑素，此法可用于测定脑白金胶囊中的褪黑素。     

FcBAK/钼磷酸电荷转移型杂化分子的合成及性能

二茂铁衍生物l-二茂铁基3-苯基丙-2-烯-1-酮(FcBAK)与钼磷酸盐Na2HPMo12O40·xH2O经室温固相合成得到有机-无机杂化分子, 通过元素分析、IR、ICP、AAS和TG等表征手段确证产物的分子组成和结构为(FcBAK)3HPMo12O40·2H2O. 固体电子光谱及ESR谱表明, FcBAK与钼磷酸之间发生了电荷转移作用, 生成电荷转移型有机-无机分子复合物, 该复合物的磁学行为表现出较强的铁磁性质, 粉末样品的室温饱和磁化强度为0.41 A·m2/kg, 矫顽力为0.0105 T, 属于软磁性有机-无机分子复合材料.     

钠离子和钾离子通道噪声扰动对神经网络 时空模式的影响

研究了钠离子和钾离子通道噪声扰动对Hodgkin-Huxley神经网络放电时空模式的影响. 发现无论钠离子通道噪声还是钾离子通道噪声扰动, 当取定一组温度、噪声强度, 随着耦合强度的增大, 神经网络放电时空斑图总能演化出螺旋波, 而且存在形成螺旋波所需的临界耦合强度. 分析发现钠离子通道噪声有利于神经网络螺旋波的形成, 而钾离子通道噪声不利于螺旋波形成. 结果还表明较低的温度能够使神经网络对噪声更加敏感. 最后, 讨论了特定参数下螺旋波与靶波之间的转化现象.     

Photothermal biological effects of monomeric erythrocyte using optical tweezers

The changes of mechanical properties and biological activities of monomeric erythrocytes are studied using optical tweezers micromanipulation technology. Firstly, the mechanical properties of irradiated erythrocyte membranes are obtained. Weaker power laser irradiation can delay the decay of the mechanical properties of erythrocytes and promote the biological activity of erythrocytes, while higher power laser irradiation damages erythrocytes. The stronger the laser irradiation is, the more obvious and rapid the damage will be. The temperature of the cell surface will be changed by regulating the laser power and irradiation time, so the biological functions of erythrocyte can be controlled. Secondly, the finite element simulation of the temperature change on the cell surface under the condition of laser irradiation is carried out using simulation software, and the precise temperature of the cell surface irradiated cumulatively by a laser with different powers is obtained. Finally, the processes of abscission, unfolding, and denaturation of hemoglobins in erythrocytes at different temperatures due to the photothermal effect are analyzed using the model. The mechanism of laser irradiation on the elasticity of erythrocyte membranes is also obtained.     

高灵敏银纳米棒阵列对农药啶虫脒的表面增强拉曼散射快速检测

The determination of pesticide residue on agricultural products is increasingly important.Exposure to pesticides can cause severe acute reactions in humans,including aplastic anemia and leukemia.In this work,we developed a rapid and sensitive method to detect acetamiprid pesticide residue based on surface-enhanced Raman scattering.Silver nanorod (AgNR) arrays were fabricated by oblique angle deposition technology and were used as SERS substrates.Prior to detection,the AgNR arrays were cleaned with nitric acid solution or a mixture of methanol and acetone.Compared to the unwashed AgNR arrays,the AgNR arrays washed with methanol and acetone shows a signal enhancement 1000 times greater than the unwashed AgNR array due to the effective removal of the impurities on its surface.The limit of detection of acetamiprid was determined to be 0.05 mg/L.In addition,the molecular structure of acetamiprid was simulated and the corresponding vibration modes of the characteristic bands of acetamiprid were calculated by density function theory.To demonstrate its practical application,the AgNRs array substrates were applied successfully to the rapid identification of acetamiprid residue on a cucumber''s surface.These results confirmed possibility of utilizing the AgNRs SERS substrates as a new method for highly sensitive pesticide residue detection.     

Post-buckling of a cantilever rod with variable cross-sections under combined load

IntroductionSinceEuler[1] ,Lagrange[2 ] ,Love[3 ] etal.investigatedtheslenderrod ,asoneofthebasicstructuralstabilityproblems ,manyattentionshavebeenpaidtothepost_bucklingofelasticrodsforalongtime .Today ,flexiblerodshavebeenwidelyusedasspring ,linkages ,robot’sarms,largeantennasandsoon .Hence ,thestudiesofpost_bucklingofelasticrodshavewideengineeringandapplyingbackgroundsinrecentdays .Basedontheassumptionthattheaxiallineoftherodisinextensible ,Timoshenkoetal.[4] examinedthepost_bucklingofco…     

轴向复合载荷作用下变截面悬臂弹性立柱后屈曲分析

基于轴线可伸长弹性杆的几何非线性理论,建立了同时作用端部轴向集中荷载和沿轴线作用分布轴向载荷的变截面弹性悬臂柱的后屈曲控制方程。采用打靶法直接求解了所得强非线性边值问题,给出了截面线性变化的圆截面柱的二次平衡路径及其过屈曲位形曲线。     

冷质部件支撑结构中压杆的热过屈曲分析

以圆杆式冷质量支撑结构中的压杆为研究对象,考虑了材料线膨胀系数α随温度非线性变化的特性及材料本构关系的非线性,基于轴线可伸长原理建立了压杆的热过屈曲数学模型;利用打靶法分别分析了材料本构关系取线性模型和非线性模型时的压杆热屈曲过程,并对二者进行了对比。研究结果表明:无论材料本构关系采用线性模型还是非线性模型,当α取常数时临界屈曲温度与柔度无关;而当α随温度非线性变化时,柔度则对临界屈曲温度产生影响;在同一柔度下,考察α对屈曲特性参数的影响规律时材料本构关系的非线性特性不可忽略;在非线性本构关系下线膨胀系数随温度非线性变化时可得到最大轴向载荷、最小横向支座反力、最小轴线总伸长量;较小的横向支座反力可以有效减小支撑结构中心收缩位移,较小的轴线总伸长量可以有效减小压杆周向固定端连接处应力。     

非均匀等离子体对平面电磁波的衰减

利用荧光灯排列形成非均匀等离子体层(面积约60cm×52cm,消耗功率约400W),研究了其对1～8GHzE波(电矢量方向平行于灯轴方向的入射波)的反射和透射的影响。结果表明,该等离子体对1～4GHz的E波具有强吸收和弱反射的特性,单程衰减最高可达8dB。利用2维分段线性电流密度递归卷积时域有限差分计算式,模拟了E波传播及其在非均匀等离子体内推进的瞬态过程,计算了等离子体对电磁波的反射和透射衰减,并与实验结果拟合,得到等离子体电子数密度峰值约9.72×1016m-3,电子与中性粒子碰撞频率约4GHz。