丙酮肟与某些芳烃相互作用的~1H核磁共振研究

Hatton和Richards通过对酰胺分子的~1H NMR谱溶剂效应的研究,提出了DMF与苯生成分子络合物的模型.如果络合物按1:1生成,那么将出现一个“饱和点”,在这点上甲基的芳香溶剂诱导位移(ASIS)的变化趋势或程度将出现一个明显的变化,事实上随着苯的摩尔分数从0到1逐渐增加时,化学位移总是有规则的逐渐移向高场.这就显示了分子络合物观点的局限性.它能被一些研究者所支持和接受,是因为它能够解释两个甲基共振峰先重合而后又分离的现象.     

Electrochemical characteristics of Ce0.8Gd0.2O1.9|La0.6Sr0.4CoO3-δ + Ce0.8Gd0.2O1.9 half-cell

The analysis of the medium temperature half-cell Ce_0.8Gd_0.2O_1.9|70 wt% La_0.6Sr_0.4CoO_3- (LSCO) + 30 wt % Ce_0.8Gd_0.2O_1.9 (CGO) has been made by electrochemical impedance, cyclic voltammetry and chronoamperometry. The shape of complex impedance plots depends on temperature and cathodic polarisation of the electrode. Nyquist (Z, Z-) plots were fitted by equivalent circuit taking into account the electrolyte properties (at very high frequencies), charge transfer process at grain boundaries (at high frequencies), and medium and low frequency O₂ reduction process at the cathode surface and inside the porous cathode material. Two different time constants have been obtained for the cathode process, i.e. for electroreduction of oxygen. It was found that the addition of CGO into the cathode material (LSCO) only somewhat decreases the surface catalytic activity but the noticeably higher low-frequency resistance (i.e. mainly diffusion-like mass transfer resistance R_D) values at lower temperatures have been calculated. It was found that the mainly bulk diffusion-limited process at T773 K deviates toward the kinetically mixed process (diffusion + charge transfer) with increasing temperature.     

Radiation effects in the transient hot-wire technique

The transient hot-wire technique is widely used for absolute measurements of the thermal conductivity and thermal diffusivity of fluids. It is well established that fluid radiation effects significantly influence these measurements, especially those for the thermal diffusivity. Corrections for radiation effects are based on the models developed and deviations of the measured data from the ideal line source model. In this paper, the effect of fluid radiation on the measurements of the thermal conductivity of n-pentane is presented. For comparison, the influence of thermal radiation effect on measurement of transparent fluids, such as argon is also shown. The difference between the influence of natural convection and thermal radiation is also demonstrated.     

Unusual volumetric and hydration behavior of the catanionic system sodium undecenoate: sodecyltrimethylammonium bromide

Following the studies on the effect of double bonds in the surfactant hydrophobic tail on the formation of mixed surfactant aggregates, we studied the viscosity and density of the system Sodium 10-undecenoate (SUD)–decyltrimethylammonium bromide (DTAB)–water. We found that the partial molar volume (pmv) and intrinsic viscosity of both, micellised and unmicellised mixtures, are non-ideal, dependent on the mixture composition and related to structural changes in micelles. These phenomena are caused by the presence of the double bond at the distal extreme of the SUD molecule, which has some affinity with water by formation of hydrogen bonds. In particular, as far as we know, this is the first report on non-ideal behavior of the pmv in mixed micelles.     

Synthesis and Structure of Mixed Ba12F19ClδBr5–δ Crystals

In the structure Ba₁₂F₁₉Cl₅ [hexagonal space group P6 2m] the two chlorides on the sites Cl(1) and Cl(2) can partially be replaced by bromide ions. Single crystals of the type Ba₁₂F₁₉Cl_δBr_5–δ with a chloride to bromide ratio up to 2 : 3 could be obtained by cooling a flux of 75 mol% BaF₂ and 25 mol% BaX₂ with X = Cl, Br. The crystal quality decreases with increasing bromide concentration. Structural parameters of five selected single crystals with different chloride/bromide ratio were studied by single crystal X-ray diffraction methods. The refined total Cl^?/Br^? population ratio in the crystals is close to the one of the flux. The lattice parameters and interatomic distances change in various ways, when the smaller chloride ion is replaced by the bigger bromide ion. The refinements show a statistical disorder on the halide sites with preferential bromide substitution on site Cl(1).     

Ga^3＋的新萃取体系的界面特性和胶团化作用研究

研究了Ｇａ~（３＋）协萃体系（Ｇａ~（３＋）－Ｄ_２ＥＨＰＡ－Ｈ_２ＭＰＡ－正十二烷－Ｈ_２ＳＯ_４）的界面吸附和胶团形成热力学，发现该萃取体系中［Ｈ_２ＭＰＡ］影响Ｄ_２ＥＨＰＡ和Ｈ_２ＭＰＡ的界面吸附性质。在中、高［Ｈ_２ＭＰＡ］范围内Ｄ_２ＥＨＰＡ与Ｈ_２ＭＰＡ的界面吸附行为相反，Ｄ_２ＥＨＰＡ的存在也影响Ｈ_２ＭＰＡ的界面吸附行为。研究了界面张力与各因素关系的数学模型，并获得某些胶团形成和界面吸附特性的物化参数。     

甲醇—乙醇—水—盐体系的等压气液平衡

木文采用CPⅡ型沸点仪测定了在93.33kPa下甲醇-乙醇-水-盐(NaCl,NaBr,Nal,LiCl,CaCl_2)体系的气液平衡数据。实验证明,当三元混合溶剂的相对组成固定时,体系的沸点与加入的盐量呈线性关系,用热力学理论导出了该线性方程,用Gibbs相律探讨了该线性关系的起因。     

A novel measurement method of Donnan potential at an interface between a charged membrane and mixed salt solution

We developed a novel measurement method of the Donnan potential difference at a charged membrane/salt solution interface. The method can measure the potential under the condition that the membrane charge density is much lower than the KCl concentration of the salt bridge. This method is very useful for obtaining the effective charge density of each layer of a bipolar membrane. The present experiments in a system of a negatively charged poly(vinyl alcohol) membrane and a single salt solution of KCl, NaCl, LiCl, CaCl₂ and LaC₃ revealed that the membrane effective charged density has the same value for all the ions. The experiments in mixed KCl and CaCl₂ solution revealed that the potential in the system is governed mainly by the concentration of the counterion having the highest valence in the system.     

吸热碳氢燃料裂解镧改性混合型催化剂的研究

制备了吸热型碳氢燃料NNJ-150和镧离子交换改性的USY、ZSM-5分子重申及混合分子筛，考察了NNJ-150在USHY、HZSM-5和两者混合物以及镧改性单分子筛和混合分子筛催化剂上的裂解反应。结果表明，ZSM-5分子筛中添加镧，对NNJ-150的单分子裂解反应有明显影响；混合分子两种分子筛之间存在协同作用，低温（500℃）下，LaUSY LaZSM-5（75：25）混合分子筛对低碳烯烃的选择性较高（41.48％），催化剂寿命较长（35min以上），能有效提高吸热型碳氢燃料NNJ-150的吸热能效。     

聚酯聚醚嵌段共聚物与1,4-二咔唑环丁烷在激发态及基态的相互作用

<正> 聚酯聚醚嵌段共聚物具有十分良好的物理和机械性能,能加工成橡胶、纤维、塑料胶粘剂等,近年来也有作为医用高分子材料的报道。所以对聚酯聚醚嵌段共聚物的研究十分活跃。然而,有关其光物理性质的研究还很少见。本文报道了混合聚醚-聚酯嵌段共聚物(MPEE)与反式1,4-二咔唑环丁烷(1,4-DCC)在激发态和基态下的相互络合作用。结果表明,MPEE可以猝灭1,4-DCC的荧光,同时形成激基复合物。在分散