紫外分光光度法研究β-环糊精与甲基橙的包结行为

利用甲基橙(MO)的吸光度随β-环糊精(β-CD)浓度的增加呈规律性的减弱,而最大吸收波长不变的性质,考察了温度、甲醇浓度、离子强度对其包结平衡常数的影响,计算得到热力学常数并讨论了包结过程的驱动力及可能的包结物结构。结果显示,包结平衡常数随温度、甲醇浓度的升高而减小,随离子强度的升高而增大。热力学常数表明整个包结过程是焓、熵联合驱动的过程,其中疏水作用是主要驱动力。     

光电协同增强的场效应对LaAlO_3/SrTiO_3界面中持续光电导的调控

LaAlO_3/SrTiO_3异质结界面体系具有新奇的二维自由电子气现象、暂态光电导效应、持续光电导效应等丰富的光电性质,是近年来科学界研究的热点之一.本文研究了场效应对LaAlO_3/SrTiO_3界面光电导效应的调控,发现光电协同增强的场效应可以使得LaAlO_3/SrTiO_3界面产生显著的持续光电导效应,进一步研究发现:在光电协同效应的影响下,随着负的背栅门电压的增加,持续光电导的数值增大,在-70 V附近达到极值;随着负的背栅门电压处理时间的增加,持续光电导的数值单调增加.LaAlO_3/SrTiO_3异质结中这种场增强的持续光电导效应可为多参数可调的光电子记忆器件的研发提供参考依据.     

Simultaneous determination of cobalt, copper and zinc by energy dispersive X-ray fluorescence spectrometry after preconcentration on PAR-loaded ion-exchange resin.

A sensitive method for the preconcentration and determination of trace amounts of Co, Cu and Zn by energy-dispersive X-ray fluorescence spectrometry (EDXRF) has been developed. The method is based on the fact that 4-(2-pyridylazo)-resorcinol (PAR) loaded Dowex anion-exchange resin (PAR-resin) can effectively adsorb Co, Cu and Zn at pH 9.0 to form PAR-metal complexes. The detection limits for Co, Cu and Zn were 1.53, 0.31 and 0.21 ppb, respectively. The precisions for five replicate measurements of the three metals were 3.4, 2.7 and 2.1% RSD, and the calibration curves were linear up to 75 microg with correlation coefficients of 0.9975, 0.9980 and 0.9985, respectively. The method was successfully applied for the simultaneous determination of Co, Cu and Zn in seawater samples at ppb levels.     

木材微结构对其传热特性影响的实验研究

对落叶松和红松的试样进行了剖面结构的扫描电镜观察,图片显示在木材内部有非常明显而规则的多孔结构。通过实验测量了不同含水率的木材试样在20-200℃范围内的导热系数,并根据其多孔结构的特点对木材的传热特性进行了理论分析。结果表明,木材微结构的不同对其传热特性有显著影响,木材多孔部分在整个传热过程中起重要作用。木材的传热特性随着其多孔部分的孔隙分布和孔隙大小的不同而变化,在相同含水率的情况下,孔隙率高而孔隙小的木材传热能力较弱。     

辣根过氧化物酶催化动力学光度法测定汞

基于辣根过氧化物酶催化H2O2-4-氨基安替比林-2,4-二氯苯酚的反应中,汞离子对于酶催化的抑制作用,建立了用动力学分光光度法测定Hg2 新方法.测定范围为1.0-5.0μg/mL,检出限为5.78×10-7g/mL,优化了测定Hg2 的实验条件并讨论了共存离子对测定的影响.本法简单、快速.     

灿烂甲酚蓝褪色光度法快速测定强酸的pH值

利用灿烂甲酚蓝在强酸条件下(0＜pH＜1.0)吸光度随溶液中H 浓度的升高而有规律的下降,提出一种快速测定溶液酸度的分光光度法.该法具有很好的精密度,10次测定结果的相对标准偏差为0.54%.与国标法(碳酸钠滴定法)相比,相对误差在2%-5%之间,具有较好的准确性.该法简单快速,消耗试剂少,成功用于浓盐酸和浓硫酸浓度的测定.     

双层A3钢靶对平头杆弹的抗侵彻性能研究

 钢板被广泛用于构建防护结构,大量文献报道了单层金属靶的防护性能,而对双层金属靶,特别是大间隙双层金属靶,报道的却很少。在轻气炮上进行了平头杆弹体正撞击由两层5 mm厚A3钢板组成的接触式和具有200 mm间隙的间隙式双层靶的实验研究,得到了两种结构的初始-剩余速度曲线。实验表明：（1）两种形式双层靶均发生了充塞剪切;（2）接触式双层靶的弹道极限是5 mm单层A3靶的1.92倍;（3） 间隙式双层靶的抗侵彻性能具有较大的分散性,通过高速摄像和对回收靶板的分析表明,该分散性产生的原因是,弹体贯穿第一层靶后存在两种典型弹道状态;（4）间隙式双层靶存在两个弹道极限;（5）接触式双层靶的弹道极限接近或者大于间隙式双层靶的弹道极限。使用ABAQUS/EXPLICIT有限元软件进行了相应的数值模拟,得到了与实验一致的现象和结果。     

Influence of strain and electric field on the properties of silicane

We investigate the influence of strain and electric field on the properties of a silicane sheet. Some elastic parameters of silicane, such as an in-plane stiffness of 52.55 N/m and a Poisson’s ratio of 0.24, are obtained by calculating the strain energy. Compared with silicene, silicane is softer because of its relatively weaker Si-Si bonds. The band structure of silicane is tunable by a uniform tensile strain, with the increase of which the band gap decreases monotonously. Moreover, silicane undergoes an indirect-direct gap transition under a small strain, and a semiconductor-metal transition under a large strain. The electric field can change the Si-H bond length of silicane significantly. When a strong field is applied, the H atom at the high potential side becomes desorbed, while the H atom at the low potential side keeps bonded. So an external electric field can help to produce single-side hydrogenated silicene from silicane. We believe this study will be helpful for the application of silicane in the future.     

TiO2陶瓷顶层膜的化学气相淀积生长研究

以ＴｉＣｌ和Ｔｉ（ＯＣ４Ｈ９）４为源物质采用热化学气相淀只（ＣＶＤ）法及射频ＰＣＶＤ法在多孔α－Ａｌ２Ｏ３陶瓷衬底上淀积生长ＴｉＯ２薄膜，观测ＴｉＯ２膜的生长方式、生长速率以及结构和表面形貌等，讨论其生长机制，评价ＣＶＤ改性生长的顶怪ＴｉＯ２陶瓷膜的气体渗透性。