提高大学物理实验教学效果的几种方法

本文阐述了提高大学物理实验教学效果的几种方法：提高认识、操作技术、故障排除、联系理论以及注重反馈。     

二级轻气炮发射过程中前冲气体的初步研究

 在二级轻气炮发射过程中,靶室内的残存气体和绕行到弹丸前方的推进气体都有可能对实验结果造成影响。利用石英传感器测量并得到了二级轻气炮高速弹丸发射时前冲气体的压力信号,并计算得到了相应的压力。实验结果表明：二级轻气炮发射时确实存在前冲气体现象,但其压力幅值较小,约为10^-2 GPa量级,不会对高压物理实验的结果造成明显的影响。     

基于副载波调频技术的光纤光栅传感网络查询

分析了副载波调频技术用于光纤光栅阵列查询的基本原理。从理论上推算了系统的查询空间分辨率及查询范围,并结合波分复用技术进行了光纤光栅传感网络的地址查询演示实验,同时使用可调谐滤波器对每个光栅信号进行了解调。实验结果很好地说明了该查询方案的可行性,且在单个光栅上的被测应变与可调谐滤波器的控制电压呈较好的线性关系。该系统具备有查询由几百个FBG组成的传感网络的潜在能力。     

原位衰减全反射表面增强红外光谱实验技术

介绍了原位研究电极,溶液界面反应的技术--衰减全反射表面增强红外光谱实验技术(ATR-SEIRAS)的产生背景和工作原理,重点描述了ATR-SEIRAS实验技术的关键:光谱电化学池的构造和薄膜电极的制备.与IRAS相比,ATR-SEIRAS技术可以更容易消除溶剂的背景吸收,获得较高的表面灵敏度,而且允许物质在电极表面自由扩散.与循环伏安相结合,利用ATR-SEIRAS技术可以实时监测电极,溶液界面问的反应.选择了利用ATR-SEIRAS实验技术原位研究功能表面的构造和性质、分子识别和反应中间体的形成等方面的应用实例,分析了ATR-SEIRAS实验技术的研究方向.     

逆流色谱仪器装置的研究进展

逆流色谱是一种快速、高效、无固定相载体的新型液-液分配色谱技术.综述了高速逆流色谱、双向逆流色谱、正交轴逆流色谱、pH-区带精制逆流色谱及螺线型圆盘柱式逆流色谱仪器装置的研究进展,介绍了高速逆流色谱-质谱联用技术、高速逆流色谱.蒸发光散射联用技术、高速逆流色谱.高效液相色谱联用技术及二维逆流色谱技术的发展状况.     

顺序注射在线稀释微量进样技术及其在自动光度法测定水中亚硝酸盐的应用

以测定环境水样中的亚硝酸盐为例,采用顺序注射技术,提出了一种智能化在线微量进样稀释分析系统(SIA系统).将测定过程中分光光度计输出的模拟电压信号,反馈至顺序注射仪,判断是否需要稀释.当获得的电压信号值小于305 mV(约相当于吸光度值0.8)时,SIA系统进入稀释程序,否则,则进入直接测定程序,两种程序均自动完成.直接测定和稀释测定的线性范围分别为1～50μmol·L-1和50～500μmol·L-1NO2-.分别在NO2-浓度水平为10,200μmol·L-1时作精密度试验,测得相对标准偏差(n=11)依次为0.7%和1.0%.该分析系统特别适合于自动分析过程中被测物质浓度变化较大而需要在线稀释的情况.     

一种新的测定微粒的电化学技术

设计了一种由2个石墨电极短路相连组成工作电极的新的电化学池装置.操作时首先通过外力按压使极少量固体微粒粘附在其中一个石墨电极表面上,然后在溶液存在下将微粒夹紧并固定在2个石墨电极表面之间进行电化学测定.电化学转化过程中生成的可溶性物质被封闭在2个石墨电极表面之间而得到测定.用该技术对钯沉积在氧化铝上而组成的催化剂的电化学行为以及黄铁矿的电化学行为进行了研究.结果表明,其兼具可电解粘合剂碳糊电极和固体微粒伏安法(voltammetry of microparticles)技术的优点而避免了各自的缺点:即不使用粘合剂,从而消除了粘合剂中杂质产生的氧化或还原电流的影响;可测定电化学转化过程中生成的可溶性物质;分辨率好、易于操作.     

Application of off-line pyrolysis with dynamic solid-phase microextraction to the GC–MS analysis of biomass pyrolysis products

Pyrolysis coupled with dynamic solid-phase micro extraction (Py-SPME) followed by GC–MS analysis was applied to the determination of volatile compounds evolved by a micro-scale off-line pyrolysis apparatus, in order to extend the information affordable with this type of analytical equipment. The Py-SPME method with a carboxen/PDMS fiber working in the retracted mode was tested on four biomass samples (switchgrass, sweet sorghum, corn stalk and poplar) for qualitative analysis of semi-volatile pyrolysis products and quantitative determination of main volatiles (C₁–C₄) pyrolysis products. The developed procedure allowed capturing and analysis of all GC analyzable compounds, without memory effects and with good peak resolution also for early GC-eluting compounds. Twelve main volatile pyrolysis products, including hydroxyacetaldehyde and acetic acid, were successfully quantified; in spite of the intrinsic variability introduced by dynamic SPME sampling, results were relatively accurate and consistent with literature data on bench pyrolysis reactors.     

Memory effects with the on-column interface for on-line coupled high performance liquid chromatography-gas chromatography: The Y-interface

When using the on-column interface for on-line high performance liquid chromatography (HPLC)-gas chromatography (GC), there is a memory effect typically equivalent to 0.5–3% of the previous transfer. The shape of peaks distorted as a result of incomplete reconcentration of the initial bands enabled mapping of the distribution of the solute material in the uncoated precolumn and deriving the mechanism which causes the memory effect. The relatively slow transfer of HPLC eluent causes liquid being sucked backwards into the narrow interspace between the transfer line and the precolumn wall. Solvent is evaporated into the passing carrier gas and is replaced by more eluent pulled into this zone, resulting in enrichment of solute material. At the end of the transfer, some of this solute material enters the transfer line and remains there up to the subsequent transfer of an HPLC fraction. This problem is avoided by replacing the on-column injector used as interface by a Y-piece in which the eluent flow from HPLC and the carrier gas are joined. The memory effect was reduced to below 0.02%.