Dielectric Studies of Binary Mixtures of some Amines—Aniline and Pyridine—in Nonpolar Solvents—Solute–Solvent Interactions

Abstract

Dielectric constant of binary mixtures of aniline and also pyridine in nonpolar liquids namely benzene, carbon tetrachloride, p-xylene and n-heptane have been measured at 455 kHz for four different temperatures. Eyring's interaction parameter G? based on the significant structure model is calculated in the mixtures using the experimentally determined value of dielectric constant.

The nature of the solvent is found to influence this parameter G? reflecting the non-specific solute-solvent interaction. The calculated value of G? is used for interpreting dipole interaction of solute molecules in the solvent environment.     

Acoustical study on ternary mixture of dimethyl acetamide (DMAC) in diethyl ether and isobutyl methyl ketone at different frequencies

The experimental density (ρ) and the velocity (U) for ternary mixture of dimethyl acetamide diethyl ether and isobutyl methyl ketone at different frequencies (2, 4, 6 and 8 MH_Z) have been measured at a constant temperature of 308 K. These data have been used to compute acoustic impedance (Z), adiabatic compressibility (K _s), intermolecular free length (L_f ), molar volume (V_m ), molar sound velocity (R), molar compressibility (B), available volume (V _a), Lennard-Jones potential repulsive term exponent (n), relative association (R _A), interaction parameter (X) and excess values of some of the above parameters for entire range of mole fraction and are interpreted to explain molecular interaction occurring in the liquid mixture.     

A Simple Coulometric Method for Determining Cu[II] and Cu[I] Contents in Various Solid Samples

Abstract

Determination of copper individual oxidation states (Cu[II] and Cu[I] in various solid samples is a rather difficult problem. Results are here presented to demonstrate that constant current coulametric techniques are useful to realize these determinations with good analytical characteristics. The analytical equivalence points obtained are based on the reversible electron transfer mechanisms: Cu[II] + 3 HC1 + 2 e CuCl^2? ₃ + 2H⁺ and : CuCl^2? ₃ +e = Cu(O) + 3 Cl^?, respectively, after quantitative dissolution in aqueous HC1 6 M. Cyclic voltammetric measurements with a carbon paste electrode are made to characterize the electron transfers involved and to investigate the analytical utility of the technique in various media. Analytical determinations are given, e.g., in the analysis of the CuO/Cu₂ O content of various samples.     

Preparation,crystal structure and luminescence of lanthanide coordination polymers with 2,2′-dimethyl-4,4′-bipyridine-N,N′-dioxide

Four coordination polymers of the bidentate ligand 2,2′-dimethyl-4,4′-bipyridine-N,N′-dioxide (L), [La(L)(NO₃)₃(H₂O)] _n (1), {[Gd₂(L)₃(NO₃)₆]·6H₂O} _n (2), {[Sm(L)₂(H₂O)₄]·3ClO₄·2L·4H₂O} _n (3) and {[Nd(L)₂(H₂O)₄]·3ClO₄·2L·4H₂O} _n (4) have been synthesized by the diffusing solvent mixture method. Results of X-ray diffraction analysis reveal that 1, with a Ln/L stoichiometry of 1:1, displays a rare 3-D three-fold interpenetrating diamondoid framework, while 2 has a Ln/L stoichiometry of 1:1.5 and exhibits a polycatenane network with a {8²,10} topology and large channels accommodated by water. Complexes 3 and 4, with Ln/L stoichiometry of 1:2, have 3-D two-fold interpenetrating diamondoid structures and large voids. Nonlinear optical property of 2 and luminescence of 3 were also investigated.     

Electrical Conductivity of Noble Gas Plasmas in the Warm Dense Matter Regime

The electrical conductivity of noble gas plasmas is investigated by using the relaxation‐time approximation in the density range 10^–5–10 g cm^–3 and temperature range 10⁴–10⁵ K. The electrical conductivity calculated shows reasonable consistency with shock wave experiments and theoretical simulations at above 2 × 10⁴ K where the Coulomb interaction dominates. A nonmetal to metal transition in helium plasma is predicted at 2.4 g cm^–3 and shown reasonable agreement with the most recent shock wave experiment (above 1.9 g cm^–3). Furthermore, the insulator‐metal transition densities of all the noble gas plasmas are predicted and compared with available results (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于多维漫反射光谱技术的复杂混合溶液成分检测

为了进行复杂混合溶液的成分检测,该文提出了一种基于多维漫反射光谱技术的浓度检测方式,通过信号中携带的不同成分的多种光学性质来进行分析。实验设计了基于超连续谱激光光源、精密电控平移台和光谱仪的检测装置,选用Intralipid-20%溶液作为研究对象,用蒸馏水配制体积百分数1%～20%的溶液,分别测量距其入射点1.5～13mm(间隔0.5mm)范围内的24点漫反射光谱信号,以偏最小二乘回归算法对单点和多点漫反射光谱信号进行建模与预测。得到建模精度最高的为距离入射位置最近的1点～13点对应的光谱信号所建立的模型,预测精度最高的为距离入射位置最近的1点～7点对应的光谱信号所建立的模型。结果表明,增加不同位置信息的光谱信号,能够提高光谱的信噪比,与传统光谱技术仅利用吸光度或反射率等单一光学性质的方法相比,增加了被测物质散射特性的影响,利用被测物质多种光学性质的变化提高了建模及预测的精度,为基于多维光谱的复杂混合溶液检测提供了基础。     

波尔多液的施用对套袋苹果铜含量的影响

以不同地区、不同果园套袋栽培红富士苹果为试材,用火焰原子吸收法对施用波尔多液的套袋苹果中的铜含量进行了测试。结果表明,不同地区、不同果园的红富士苹果中的铜质量分数为0．45～1．07mg／kg,均低于我国卫生标准（GB15199-94）中水果中铜元素限量10mg／kg,其中套袋苹果中铜元素平均含量是不套袋苹果中铜元素平均含量的62．7％。每天食用适量苹果可以满足人体对铜元素的需求,且不易产生铜中毒等副作用。     

Approximation of the variance gamma model with a finite mixture of normals

We investigate the possibility of approximating the variance gamma distribution with a finite mixture of normals. Therefore, we apply this result to derive a simple historical estimation procedure by means of the Expectation Maximization algorithm.     

蒸气压力和流速对低浓度酒精-水混合蒸气微细竖直管外凝结的影响

本文在不同蒸气压力和流速状态下对低浓度的酒精-水混合蒸气在微细竖直圆管外表面Marangoni凝结传热特性进行了可视化实验研究,观测到不同工况下的凝结形态。结果表明,随着过冷度的增加,凝结传热系数急剧升高,凝结传热系数在达到峰值后开始下降,下降曲率相对较缓;随着压力的增加,凝结传热系数在大的过冷度下增幅较大。蒸气流速的影响与压力的影响类似。可视化研究表明蒸气压力和流速大小对凝结速率影响较大。