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151.
A method based on Pitzer's model has been used for calculation of the solubilities of carnallite type double salts crystallizing in the systems MeX–MgX2–H2O (Me=Li, NH4, K, Rb, Cs; X=Cl, Br). The solubility of congruently soluble double salts was also determined experimentally at 25–75°C. The results from studies of the solubility diagrams of ternary carnallite type water-salt systems over a wide temperature range are summarized. It is found that the width of the crystallization region for each of the salts can be explained by the relative differences in the solubilities of the ternary solution components (MeX, MgX2·6H2O and MeX·MgX2·6H2O) and by a change of temperature, and by the effect of temperature on the solubility. A method is proposed for calculating Pitzer's ternary parameters of interionic interaction (MN and MNX) on the basis of experimental data for the solubility in water of the double salts crystallizing in the corresponding ternary water-salt systems. 相似文献
152.
Roger Douillard 《Colloids and surfaces. B, Biointerfaces》1993,1(6):333-340
Knowledge of the equation of state of adsorbed or deposited layers of proteins at the air/water interface is of fundamental interest in the understanding of the surface activity of these molecules. Using scaling laws of current polymer theories, it has been shown that the equation of state of the interfacial layer in the semi-dilute regime should relate the surface pressure to the surface concentration through a power law. The exponent of this power law should reflect the quality of the solvent and the conformation of the adsorbed polypeptide chain. In the case of β-lactoglobulin layers, in the range of surface concentrations that should correspond to the semi-dilute regime, the relationship between surface pressure and surface concentration is expressed as a power law. The exponent of this power law is strongly influenced by the nature of the aqueous substrate and by the net charge of the protein molecule. The use of scaling laws gives a coherent view of the expansion of the polypeptide chain in the interfacial layer and of the relationship between surface concentration and surface pressure in the semi-dilute regime. This result favours a strong similarity between β-lactoglobulin and a polymer chain in the interfacial layer. It is concluded that current theories of polymer adsorption could be applied to interfacial protein layers. 相似文献
153.
手性环丙烷类衍生物双水解转换的研究 总被引:3,自引:0,他引:3
具有四个新手性中心的螺环/环丙烷类化合物4在丙酮-12%HCl溶液中50℃下 发生双手性辅基-双水解转换反应,得到了手性环丙烷/双半缩醛类化合物,螺 [1-溴-4-羟基-5-氧杂-6-氧代双环[3.1.0]己烷-2,2′-(3′-亲核氧基- 4′-羟基丁内酯)](5),化学产率65%-79%,光学纯度ee≥98。通过元素分 析,[a]D^20,UV,IR,^1H NMR,^13C NMR,MS以及X射线四圆衍射测定,确认了它们的 化学结构、立体化学和绝对构型。该双半缩醛类化合物的合成方法学研究可为官能 团的转换,为某些复杂结构的手性化合物提供新的合成方法和途径。 相似文献
154.
Under steady-state conditions, the current equations of the second-order EC, ECE and DISPI reactions at microdisk, microspherical and microring electrodes are derived with the aid of the concept of the reaction layer. The conditions under which these equations would be valid are also discussed. Using these equations, methods to determine the kinetic parameters for the second-order EC, ECE and DISPI reactions are presented. The reduction of 2,6-diphenyl-pyrylium cation and oxidation of triphenylamine were investigated as examples of the second-order EC and ECE reactions. 相似文献
155.
双电层相互重叠时蒙脱胶体表面阴离子的负吸附 总被引:2,自引:0,他引:2
本文用Ag-AgCl电极判断平衡,测定双电层处于不同重叠程度下肢体表面阴离子的负吸附量Γ.结果表明,胶体表面双电层相互重叠程度可由两胶体表面间的中点电位φd与外Helmhotz面处的电位φd之比表征;阴离子负吸附随双电层重叠程度和电解质浓度的增加而显著减小. 相似文献
156.
运用一种植物油的系统分析方法测定蓖麻油的精细组分,这包括皂化,BF3-MeOH甲基化,GC-CIMS法测定脂肪酸碳链长度和不饱和度,AMP衍生化,GC-EIMS测定不饱和脂肪酸的双链位置,分析了蓖麻油的十一种脂肪酸组分,有五个为未知组分,并测定了其中三个组分的双链位置。 相似文献
157.
The electric conduction in the fibrous medium constructed by a homogeneous array of parallel, identical, charged, circular cylinders having an arbitrary zeta potential filled with the solution of a symmetrically charged electrolyte is analytically examined. The thickness of the electric double layers surrounding the dielectric cylinders is assumed to be small relative to the radius of each cylinder and to the gap width between two neighboring cylinders, but the polarization of the mobile ions in the diffuse layers is allowed. The effect of interactions among individual cylinders is taken into explicit account by employing a unit cell model. The appropriate equations of conservation of electrochemical potential energies of ionic species are solved for each cell, in which a cylinder is envisaged to be surrounded by a coaxial cylindrical shell of the fluid solution. Analytical expressions for the effective electric conductivity are obtained in closed forms as functions of the porosity of the fiber matrix and other characteristics of the porous system. Comparisons of the results of the cell model with different conditions at the outer boundary of the cell are made. Under an otherwise identical condition, the electric conductivity in a porous medium composed of an array of parallel cylinders in the transverse direction is smaller than that of a suspension of spheres. The effect of interactions among the cylinders or spheres on the effective conductivity can be quite significant under appropriate conditions. 相似文献
158.
The photoluminescence of Co-Al-layered double hydroxide 总被引:1,自引:0,他引:1
Shuai Sun Wan Guo Hou 《中国化学快报》2007,18(11):1371-1373
We report a new optical behaviour of pure Co-Al-layered double hydroxide (LDH).It was found that the Co-Al-LDH sample could emit fluorescence without any fluorescent substances intercalated.Its excitation spectrum shows a maximum peak near the wavelength 370nm,the maximum emission peak appears at 430 nm and the photoluminescence colour of the Co-Al-LDH sample is blue.This new optical property will be expected to extend the potential applications of LDHs in optical materials field. 相似文献
159.
160.
The electrochemical double layer between Cu(111) electrodes and aqueous electrolytes (F− and SO2−4 at various pH values) was studied by means of linear scan voltammetry and ac impedance measurements. It is found that electrochemisorption of oxygen species proceeds on the Cu(111) surface in the potential regions more negative than the electrodissolution potential of copper. The adsorption-desorption kinetics are analysed; the anodic and cathodic symmetry coefficients are found to be equal (α = β = 0.3), and the standard rate constant is k° = 4 × 10−10cm s−1. 相似文献