库仑双点滴定法研究——Ⅰ.离子选择电极电位法

本文提出以离子选择性电极为指示电极的库仑双点滴定的实验方法,推导出定量公式和相对误差公式,探讨了影响准确度的主要因素。     

Red‐ and Green‐Emitting Iridium(III) Complexes for a Dual Barometric and Temperature‐Sensitive Paint

A new dual luminescent sensitive paint for barometric pressure and temperature (T) is presented. The green‐emitting iridium(III) complex [Ir(ppy)₂(carbac)] (ppy=2‐phenylpyridine; carbac=1‐(9H‐carbazol‐9‐yl)‐5,5‐dimethylhexane‐2,4‐dione) was applied as a novel probe for T along with the red‐emitting complex [Ir(btpy)₃], (btpy=2‐(benzo[b]thiophene‐2‐yl)pyridine) which functions as a barometric (in fact oxygen‐sensitive) probe. Both iridium complexes were dissolved in different polymer materials to achieve optimal responses. The probe [Ir(ppy)₂(carbac)] was dispersed in gas‐blocking poly(acrylonitrile) microparticles in order to suppress any quenching of its luminescence by oxygen. The barometric probe [Ir(btpy)₃], in turn, was incorporated in a cellulose acetate butyrate film which exhibits good permeability for oxygen. The effects of temperature on the response of the oxygen probe can be corrected by simultaneous optical determination of T, as the poly(acrylonitrile) microparticles containing the temperature indicator are incorporated into the film. The phosphorescent signals of the probes for T and barometric pressure, respectively, can be separated by optical filters due to the ≈75 nm difference in their emission maxima. The dual sensor is applicable to luminescence lifetime imaging of T and barometric pressure. It is the first luminescent dual sensor material for barometric pressure/T based exclusively on the use of Ir^III complexes in combination with luminescence lifetime imaging.     

The effect of variations in barometric pressure and other factors on the ebullioscopic determination of molecular weights,with special reference to the use of the menzies differential thermometer

A theoretical treatment of the effect of variations in barometric pressure and other factors on the ebullioscopic determination of molecular weights leads to general expressions relating the variations in barometric pressure with the ebullioscopic constant of the solvent and with the temperature sensitivity of the Menzies differential thermometer. Since these variations can affect significantly the accuracy of ebullioscopic molecular weight determinations, a single comprehensive correction term is calculated for each of the usual combinations of ebullioscopic solvent and thermometer filling liquid; this term enables results obtained at different pressures to be corrected to standard atmospheric pressure, thus eliminating the pressure effect. Finally a statistical analysis of some experimental results illustrates the validity of the correction term for the combination of benzene as ebullioscopic solvent with benzene as thermometer filling liquid.     

Comments on the geometric approximation to the second-order perturbed energies

It is shown that the ideas similar to those behind the ordinary geometric approximation can be efficiently used to speed up the convergence of the coupled Hartree-Fock iterative procedure in the density matrix formalism. The formulation of the geometric approximation in the case of multiple perturbation is also considered and an alternative second-order energy formula is proposed. The validity of the upper bound formula for the error of the geometric approximation denied by Burrows, is discussed.     

关于单电位跃扩散情况的光谱电化学关系式的研究

本文对 J.W.Strojek 等发表的单电位跃扩散控制的光谱电化学关系式进行了讨论。推导了简单电荷转移反应产物在测量波长下无吸收时的光谱电化学关系式,并以光度试剂5-Br-PADAP 的电极还原反应进行了验证,结果满意。     

Energy-density relations in momentum space

The integrated Hellmann-Feynman theorem is used to derive a rigorous relation between the energy and the electron density in momentum space. Choosing the electron mass as a differential parameter, we obtain a formula corresponding to the Wilson-Frost formula in coordinate space. Analysing the mass-dependence of momentum density, we then show that the present formula is equivalent to one of the previous results deduced from the virial theorem. Use of the integral Hellmann-Feynman theorem is also discussed. Several illustrative examples are given for the calculation of energy from momentum density.     

The density profile of hard sphere liquid system under gravity

The density profile of hard sphere liquid under gravity is calculated by using density functional theory and Monte Carlo simulation method. The two methods give consistent results for a wide range of parameters. Meanwhile, the validity range of the density functional theory is also established. The results are quite different from the barometric height distribution rho(z)=rho(0) exp(-zL(G)) in almost all cases studied, which indicates that the interaction between particles plays an important role in the density distribution under external fields. Moreover, the crystallizing phenomenon is also predicted at the bottom part of the system under strong gravitation.     

关于球形小液滴热力学公式及其气液平衡条件的讨论

依据热力学第一和第二定律,从不同角度导出了球形小液滴的热力学基本公式。明确指出公式中的压力为液体相的压力,不是气相压力。分别用熵判据和Gibbs自由能判据证明了小液滴的气液相平衡条件为物质在两体相的化学势相等。强调指出:相平衡条件具有普适性,与是否为孤立体系或封闭体系及其类型无关,不仅适于球形液滴,对其他形状的液体也适用。对文献中存在的相关问题进行了较详细的讨论,澄清了一些容易模糊的认识。     

中药色谱指纹图谱相似度计算中保留时间校正方法的研究

从保留时间校正方法对线性推移、非线性推移和时间延迟的校正效果方面探讨了保留时间校正方法的适用范围。认为一点法校正仅能校正线性推移;两点法可以校正时间延迟和线性推移,并能部分校正非线性推移。多点法使用分段线性逼近的方法对非线性推移有良好的校正效果。     

光谱带宽与分析测试误差的关系

研究了光谱带宽与分析测试误差的关系．从理论上阐明了光谱带宽会引起吸收光谱仪器的分析测试误差,并给出了计算公式．用青霉素钠、青霉素钾的分析测试数据和文献报道的数据,进一步说明了光谱带宽对分析测试误差的影响．分析测试工作者一定要特别重视对光谱带宽的选择．     

Transferable integrals in a deformation density approach to crystal orbital calculations. IV. Evaluation of angular integrals by a vector-pairing method

A general method for performing angular integrations is presented. The method depends on the fact that the integral must be invariant under rotations of the coordinate system, and it also makes use of combinatorial analysis. In most cases the method presented is computationally much faster than alternative methods of angular integration using Condon–Shortley coefficients. Applications to charge density analysis and Fourier transforms are discussed, and a general formula for the action of angular momentum projection operators on functions of the Cartesian coordinates is derived. A general angular integration formula for an m-dimensional space is also given.     

临界点二级相变的有限时间热力学逼近

应用内可逆卡诺循环的方法,导出了各种物质在临界点附近可逆与不可逆二级相变普遍适用的比热跃变公式以及广义的爱伦菲斯特方程。对简单(P,V,T)系统、超导、电介质顺电一铁电二级相变进行了应用讨论。     

A laplace transform technique for calculating diffusion time lags

A simple formula for diffusional time lags is derived for systems governed by linear equations with source terms. This formula is used to calculate the time lag for systems in which diffusion, dissolution and reversible or irreversible reactions occur. It is also shown that time lags can be calculated for nondiffusional systems. The application of time lags to pharmacokinetics is discussed in particular     

Surface anchoring and the saturation behaviour of a NLC cell under external electric and magnetic fields

Based on the modified Rapini-Papoular formula for surface anchoring energy, the saturation behaviour of a weak anchoring nematic liquid crystal cell under electric and magnetic fields has been studied by the methods of analytical derivation and numerical calculation. The results show that the transition at saturation point may be second order, as many authors have predicted. However, it may also be first order. The condition for the first order transition is deduced; it is related to the anchoring parameters. The influence of anchoring on the saturation field strength is also discussed, both for second and for first orders; the results are shown by graphically.     

On the theory of the effective nuclear magnetic relaxation time T2e and its application to polymer melts

A general expression for the magnetization decay of a multipulse group is derived. This formula is applied to a three-component model of molecular motions in polymer melts. The influence of the several components on the magnetization decay is discussed. The relation of the effective nuclear magnetic relaxation time T_2e to the Anderson-Weiss formula is also shown, and an analytical expression for the transverse relaxation in melts is derived. Finally T_2e is compared with the relaxation time in the rotating frame T_1ρ in the melt. The theoretical results for T_2e are tested with measurements of frequency dependence in polyethylene melts.     

Theory of the decay of molecular superexcited states

The decay processes of the superexcited state of a diatomic molecule are investigated theoretically. A general formula for the branching ratio for preionization and predissociation is derived using partitioning of the Green function. The predissociation and preionization probabilities per unit time are obtained in perturbation theory, employing the semiclassical theory and the local complex potential method based on the adiabatic vertical transition approximation for preionization. Some new features in the predissociation probability expression obtained are discussed. It is 0shown that the vibrational distribution of the molecular ions produced could be very different not only from that for the direct ionization transition, but also from that for the transition from an autoionizing state which does not couple to a dissociative state.     

Point-like impurity-dislocation interactions in smectic A liquid crystals

The displacement field created in the neighbourhood of a point-like impurity, its self-energy and point-like impurity-dislocation interaction are calculated for a smectic A liquid crystal in the approximation of small deformations. The binding energy of a point defect to an edge dislocation is also estimated. The use of the Peach-Kochler formula as a basis for the calculation of the dislocation interaction with other defects is discussed.     

Referenced Dual Pressure‐ and Temperature‐Sensitive Paint for Digital Color Camera Read Out

The first fluorescent material for the referenced simultaneous RGB (red green blue) imaging of barometric pressure (oxygen partial pressure) and temperature is presented. This sensitive coating consists of two platinum(II) complexes as indicators and a reference dye, each of which is incorporated in appropriate polymer nanoparticles. These particles are dispersed in a polyurethane hydrogel and spread onto a solid support. The emission of the (oxygen) pressure indicator, PtTFPP, matches the red channel of a RGB color camera, whilst the emission of the temperature indicator [Pt^II(Br‐thq)(acac)] matches the green channel. The reference dye, 9,10‐diphenylanthracene, emits in the blue channel. In contrast to other dual‐sensitive materials, this new coating allows for the simultaneous imaging of both indicator signals, as well as the reference signal, in one RGB color picture without having to separate the signals with additional optical filters. All of these dyes are excitable with a 405 nm light‐emitting diode (LED). With this new composite material, barometric pressure can be determined with a resolution of 22 mbar; the temperature can be determined with a resolution of 4.3 °C.     

A simple formula for the temperature dependence of the relaxation frequency in glassy systems

A simple,five-parameter empirical formula for the temperature dependence of the relaxation frequency is presented. It is shown that this formula reduces to the Arrhenius equation at higher temperatures and to the Vogel-Fulcher-Tamman equation at lower temperatures. Apart from parameters which may be obtained independently from either equation the proposed formula contains an additional parameter describing the sharpness of the transition between the regions of validity of Arrhenius or Vogel-Fulcher-Tamman equation. The applicability of the formula is tested on dielectric relaxation data of acrylic polymers and on other dielectric data available in the literature. The physical meaning of individual parameters is discussed.     

Liquid-structure forces and electrostatic modulation of biomolecular interactions in solution

Molecular interactions in solution are controlled by the bulk medium and by the forces originating in the structured region of the solvent close to the solutes. In this paper, a model of electrostatic and liquid-structure forces for dynamics simulations of biomolecules is presented. The model introduces information on the microscopic nature of the liquid in the vicinity of polar and charged groups and the associated non-pairwise character of the forces, thus improving upon conventional continuum representations. The solvent is treated as a polar and polarizable medium, with dielectric properties described by an inhomogeneous version of the Onsager theory. This treatment leads to an effective position-dependent dielectric permittivity that incorporates saturation effects of the electric field and the spatial variation of the liquid density. The non-pairwise additivity of the liquid-structure forces is represented by centers of force located at specific points in the liquid phase. These out-of-the-solute centers are positioned at the peaks of liquid density and exert local, external forces on the atoms of the solute. The density is calculated from a barometric law, using a Lennard-Jones-type solute-liquid effective interaction potential. The conceptual aspects of the model and its exact numerical solutions are discussed for single alkali and halide ions and for ion-pair interactions. The practical aspects of the model and the simplifications introduced for efficient computation of forces in molecular solutes are discussed in the context of polar and charged amino acid dimers. The model reproduces the contact and solvent-separated minima and the desolvation barriers of intermolecular potentials of mean force of amino acid dimers, as observed in atomistic dynamics simulations. Possible refinements based on an improved treatment of molecular correlations are discussed.