电导率和摩尔电导率与浓度关系的教学讨论

根据电导率和摩尔电导率的物理意义,通过简单计算,确定了参与导电的离子数目与电解质溶液浓度或电离度之间的关系,由此分析说明了电导率和摩尔电导率与电解质浓度的关系。方法简单清晰,便于学生领会理解。     

Evaporation of Electrolyte during SVET Measurements: The Scale of the Problem and the Solutions

The objective of this work is to investigate the scale of the effect of spontaneous solution evaporation during SVET (Scanning Vibrating Electrode Technique) measurements and demonstrate how it biases the final results. When SVET maps are continuously acquired for more than several hours, the measured currents are smaller than expected. This is attributed to solvent (typically water) evaporation which leads to an increase in solution conductivity over time. If this is not considered when converting the measured potential differences into the local current densities, the SVET results display currents smaller than the true ones. Here, this effect is studied with a platinum disk electrode as source of a constant current and a model corroding system consisting of the AA2024/CFRP galvanic couple. Corrective actions are proposed to mitigate the problem, either in the experimental set‐up or as numerical correction.     

Comparison of Common Solvent Evaporation Techniques in Organic Analysis

Abstract

Isolation of organic constituents from water frequently involves an extraction with a large volume of organic solvent which must be reduced to achieve the desired sensitivity. The objective of this research was to evaluate common solvent evaporation techniques to determine which are acceptable for use in pollutant analysis. Techniques for solvent reduction from 200 to 10 mL (macro) and 8 to 0.2 mL (micro) were evaluated. The macro concentration technques included Kuderna-Danish (K-D) concentration, rotary evaporation, evaporation on a hot plate in an Erlen-meyer flask, and heated nitrogen blowdown in an Erlenmeyer flask. The micro techniques included micro K-D concentration, nitrogen blowdown, and nitrogen blowdown with a modified Snyder column. A series of model compounds covering a wide range of boiling points (108° to 323°C) and polarity was used. Based upon recovery efficiency alone, nitrogen blowdown was significantly superior to the other macro techniques; however, its extreme slowness gave K-D the highest Figure of Merit. With methylene chloride as the solvent, nitrogen blowdown with a column was the superior technique.     

Conductivity and the electric modulus in polymers

At relatively high temperatures and low frequencies the electrical properties of many polymers are dominated by ionic conductivity. In cases where the glass transition is obscured by conductivity, it can be revealed by treating the data in terms of the electric modulus. The magnitude of the activation energy for conductivity (24–67 kcal/mol) for Nylons 6, 66, and 6I, polybutylene terephthalate, and polycarbonate indicates that the transport of charged particles requires the motion of polymer segments.     

W／O型微乳液活化能和导电机理研究

电导行为是微乳液的重要性质之一。自Lagourette和Lagues发现了W/O型微乳液电导渗透(Percolation)现象后,人们开始了微乳液导电机理的研究。较流行的观点认为,界面层中表面活性剂分子的阴离子在微乳颗粒碰撞时发生跃迁而使W/O型微乳液具有导电性。     

Investigation of the Thermal Conductivity of Selected Rare Earth Aluminates

As a part of the thermophysical property studies on rare earth based oxide ceramics thermal conductivity of the aluminates of samarium and dysprosium was investigated employing laser flash technique and covering a temperature range from 673 to 1373 K. Heat transport behaviour was briefly examined by analysing the variation of thermal resistivity as a function of temperature. This revised version was published online in July 2006 with corrections to the Cover Date.     

Diagnostics of an RF Plasma Flash Evaporation Process Using the Monochromatic Imaging Technique

The high densities and high gas temperature of rf plasmas at pressures near 1 atm are favorable for the development of plasma sources capable of evaporating solid precursors in the plasma zone. In the cooler region downstream of the plasma, the evaporated material condenses to nanoparticles and/or coatings. The complete evaporation of precursors injected into a thermal plasma depends on plasma and precursor parameters and is studied in this paper. Since many parameters contribute to the evaporation, fast experimental techniques are necessary to carry out a systematic study of the evaporation process. The monochromatic imaging technique applied in this work uses an intensified CCD camera with optical filters for the detection of characteristic plasma emission lines. The high spatial and temporal resolution of this technique results in a detailed picture of plasma emission and particle evaporation for different process parameters. These results are compared to model calculations for particle evaporation.     

A Comparative Analysis of the Changes During Evaporation of Three Different Commercial Emulsion of Unknown Composition

Optical microscope and centrifugation were used to observe the structure change during evaporation of three different commercial emulsions of unknown composition. The degree of evaporation under an infrared lamp at 70°C was determined from the changed weight of a microscope slide with the emulsion on a defined area and thickness. The results revealed information as to which kind of structure would appear after evaporation.     

电热板蒸发–重量法测定水中全盐量

建立了电热板蒸发–重量法测定水中全盐量的方法。采用电热板对过滤后的水样进行蒸发预处理,然后以重量法测定样品中的全盐量。取样体积为100 m L,以陶瓷蒸发皿为容器,恒重指标为质量偏差±0.5 mg,设置电热板蒸发温度为350℃,以差减重量法测定水中全盐量,方法线性范围为40~2 000 mg/L,检出限为10 mg/L,3种质量浓度水平实际样品的加标回收率在90.2%~110%之间,样品测定结果的相对标准偏差为2.8%~5.2%(n=6),有证标准物质测定结果与标准值相对误差为–1.9%~2.1%。该方法准确度高、稳定性好,适用于水中全盐量的测定。     

SrCeO3的微波合成及离子导电性质研究

ＳｒＣｅＯ_３的微波合成及离子导电性质研究徐秀廷，崔得良，冯守华，徐如人（吉林大学无机水热合成开放研究实验室，长春，１３００２３）关键词ＳｒＣｅＯ_３，微波合成，离子电导在复合氧化物中，ＳｒＣｅＯ３由于具有电子和离子混合导电性质而成为潜在的电极材料。另...     

Analysis of the Phase Changes During Evaporation of Emulsions with Different Oil Phases

Emulsions surfer alterations in their microstructure after applied on the skin, because of the interaction with skin constituents and mainly by the evaporation of volatile components. These alterations are not even considered by cosmetic formulators, but they are extremely important because they can act on formulation stability, on delivery and on permeation of actives and also on the ability to build the occlusive film, responsible for skin's moisturization. This research studied the phase changing during evaporation of emulsions made with three different oil phase: mineral oil, avocado oil, and isocethyl/stearoil stearate, as a function of the decrease on water ratio, using phase diagrams and evaporation test. It was observed the formation of liquid crystalline phases and their transition along the evaporation path for emulsions with the three different oil phases. It was also observed that these transitions occurred in different water ratios.     

稀土双(11-钨硅酸)钾的质子导电性研究(英)

研究了K13［Ln（SiW11O39）2］nH2O（Ln=La，Ce，Pr，Nd，Sm，Gd）的质子导电性研究表明其导电性不仅与物质本性有关，也与外界条件如温度、频率等有关，不同结构的杂多化合物给出不同结构的质子导电性．总结了质子导电性随温度、结晶水数目、频率的变化总趋势．基于实验数据得出一些重要结论，所得数据未见文献报道．     

电导法确定二元体系中离子的浓度

本文从电化学基本原理出发,推导出稀溶液中二元混合组分的电导与各组分当量浓度的关系,并通过测定纯组分的电导－当量浓度标准曲线,来确定二元混合组分的标准曲线在对其中一组分浓度确定的基础上,可很容易计算另一组分的浓度。该法简便、快速,有望成为化学分析和仪器分析的一个很好的补充。     

层状三元簇合物的电子结构和导电性研究 （Ⅱ）LiMO_2天机高聚物的导电机理

本文在双子晶格导电模型的基础上，运用ＳＣＣ－ＥＨＭＯ方法，研究了高性能二次电池阴极材料ＬｉＭＯ_２（Ｍ＝Ｔｉ~（３＋），Ｖ~（３＋），Ｃｒ~（３＋），Ｃｏ~（３＋），Ｎｉ~（３＋），Ｎｂ~（３＋）等）的电子结构和导电性关系。对不同材料导电性的悬殊差异给予理论解释，进一步发展了双子晶格导电模型。     

Deformation Potential Approach to the Calculation of Mobilities of Carriers and Conductivity of trans-Polymonocyanoacetylene

The deformation potential theory for one-dimensional organic polymer is studied. This approximation is then used to calculate the mobilities of carriers and the conductivity of trans-polymonocyanoacetylene (PMCA). The results of calculations are in fairly good agreement with experimental data.     

温度,压力对多省并醌类聚合物导电性能的影响

以氯化锌为催化剂，利用多环芳烃蒽，芘等的不同酸酐如１，２，４，５－均苯四甲酸二酐，四氯苯酐等，在３０６℃逐步聚合得到多省并醌类聚合物，仔细纯化后在不同温度，压力下对其他电导率进行了测量，研究了温度，压力对其电导率的影响。     

Modeling and Spectroscopic Investigations on the Evaporation of Zirconia in a Thermal rf Plasma

The evaporation process of zirconia powders injected in a thermal rf plasma is investigated. Both model calculations and optical emission spectroscopy are used to study the evaporation behavior. Gas temperatures and velocity distributions are determined numerically from conservation laws and Maxwell equations. The influence of plasma and particle parameters on the thermal history of entrained particles is discussed. Asymmetric Abel inversion is applied to detect asymmetric emission profiles in the plasma source. Spectroscopic measurements reveal that evaporated zirconium is concentrated near the axis of the plasma. Numerical calculations show that line-integrated emission profiles can be used to distinguish the cases of complete and incomplete evaporation. Axial emission profiles confirm that the evaporation zone is shifted upstream of the plasma when smaller precursor particles are used.     

多格错仁盐湖卤水冷冻、日晒两步法浓缩制卤研究

藏北无人区的多格错仁盐湖水化学类型为氯化物型,该湖水钾、锂资源品位好;结合自然条件制定该低矿化度卤水在高寒区冬季制卤工艺路线。通过冷冻、日晒两步法成功制得了富含钾、锂的精制卤水;对硫酸钙在该卤水蒸发过程中的过饱和溶解度与石膏缓析现象进行了解析。     

Effect of Different Sterilization Methods on the Microbial and Physicochemical Changes in Prunus mume Juice during Storage

This study evaluated the pasteurization (P), ozone (O₃), ultrasonic (US), and high-hydrostatic-pressure (HHP) sterilization approaches for processing of Prunus mume regarding browning factors and microorganisms, compared with non-sterilization (control check, CK) treatment. The microorganisms (total bacterial count and fungi and yeast count) in the juice were identified after different sterilization techniques, while the quality parameter changes (degree of browning, color measurements, total phenolic content, reducing sugar, ascorbic acid, 5-hydroxymethyl furaldehyde (5-HMF), amino acid nitrogen, total soluble solids (TSS), pH value) were investigated. The results indicate that P and HHP treatment reduced non-enzymatic browning while substantially impacting the color measurements, TSS, and pH, while the sterilization effect was remarkable, with a rate exceeding 90%. Furthermore, the Prunus mume juices treated with P and HHP sterilization were used as the objects, and the CK group was used as the control group. They were placed at 4 °C, 25 °C and 37 °C, respectively, and stored in dark for 15 d. Sampling and determination were carried out on 0, 3, 6, 9, 12, and 15 d, respectively. M-&-Y (molds and yeasts) were not detected in the late storage period, and no obvious microbial growth was observed during storage, indicating that P and HHP treatments could ensure the microbial safety of Prunus mume juice. P- and HHP- treated Prunus mume juice has better quality and low temperature storage is beneficial for maintaining the quality of Prunus mume juice. Therefore, P treatment or HHP treatment combined with low temperature storage could achieve a more ideal storage effect. Overall, this study conclusively established that P and HHP methods were suitable for sterilizing Prunus mume juice. These techniques minimally affected overall product quality while better maintaining the quality parameters than the untreated juice samples and those exposed to O₃ and US treatment.