环状高分子对胶体稳定性影响的理论研究

将改进的基本度量理论与热力学微扰理论相结合,提出了胶体/高分子系统排空相互作用的IRDFT理论。该理论解释了在实际胶体系统中起重要作用的排斥体积效应和高分子链内相关性的竞争机制。应用该IRDFT,分别以线性链状和环状结构的高分子及其单体为排空元,计算了不同排空元条件下的胶体间排空相互作用。研究表明:对于絮凝破坏,自由环状高分子具有更大的优势。     

基于XDLVO理论解析MBR膜污染研究进展

膜污染问题严重制约了膜生物反应器(MBR)的广泛应用,因此膜污染机制的研究对于有效控制膜污染十分重要。XDLVO理论合理地解析了范德华力、极性作用力、双电层作用力在膜污染过程中的贡献,有效地揭示了膜污染机理。本文首先阐述了XDLVO理论;然后运用XDLVO理论,解析界面微距离范围内膜表面凝胶层及泥饼层形成过程;最后总结了XDLVO理论在MBR膜污染方面的应用,并对该领域未来的研究方向进行了展望。     

固液界面纳米气泡研究

固液界面纳米气泡是近十年来表面科学的重要发现之一。从利用原子力显微镜(AFM)在固液界面上观察到纳米气泡以来,科学工作者们已经证实了纳米气泡在固液界面上存在。由于其在微机电系统(MEMS)、微生化系统、表面科学、流体动力学等领域潜在的应用价值,各国学者们对纳米气泡的自身性质及影响因素已经开展了多方面的研究。但纳米气泡稳定性(反常的长寿)的原因仍然是未解决的问题之一。本文综述了纳米气泡的形成及影响因素,重点评述了纳米气泡稳定性理论,包括线张力理论、动态平衡理论、杂质理论和克努森气体理论等。同时,介绍了固液界面纳米气泡的应用,并展望了未来研究的重点和方向。     

Generalized Langevin theory on the dynamics of simple fluids under external fields

A theory on the time development of the density and current fields of simple fluids under an external field is formulated through the generalized Langevin formalism. The theory is applied to the linear solvation dynamics of a fixed solute regarding the solute as the external field on the solvent. The solute-solvent-solvent three-body correlation function is taken into account through the hypernetted-chain integral equation theory, and the time correlation function of the random force is approximated by that in the absence of the solute. The theoretical results are compared with those of molecular-dynamics (MD) simulation and the surrogate theory. As for the transient response of the density field, our theory is shown to be free from the artifact of the surrogate theory that the solvent can penetrate into the repulsive core of the solute during the relaxation. We have also found a large quantitative improvement of the solvation correlation function compared with the surrogate theory. In particular, the short-time part of the solvation correlation function is in almost perfect agreement with that from the MD simulation, reflecting that the short-time expansion of the theoretical solvation correlation function is exact up to t(2) with the exact three-body correlation function. A quantitative improvement is found in the long-time region, too. Our theory is also applied to the force-force time correlation function of a fixed solute, and similar improvement is obtained, which suggests that our present theory can be a basis to improve the mode-coupling theory on the solute diffusion.     

论结构主义学习观与化学教学改革

结构主义理论越来越受到教育界的关注,这种理论带给新一轮基础教育课程改革许多值得深思的理念。本文在结构主义理论的基础上,从新知识观的视角出发,着重论述了结构主义学习观在当前基础教育课程改革中的作用以及化学教学在以结构主义学习观为理论指导下教师观念的转变。     

用解析Ross变分微扰理论研究蛋白质盐溶液的渗透压

采用软球三Yukawa势代替文献中的硬核双Yukawa势描述带电蛋白质分子之间的色散吸引、色散排斥和屏蔽静电排斥作用, 采用Ross变分微扰理论推导出解析状态方程(EOS), 克服了文献中常用的平均球近似对多Yukawa势存在的困难. 应用新理论研究了牛血清蛋白(BSA)-NaCl水溶液在不同pH值、不同浓度下的渗透压. 结果表明该理论独立参数的个数仅比林阳政等人最近提出的理论多一个, 而精确度有很大提高. 分析表明, 对于分子量大的蛋白质溶液体系采用新的软球理论比硬球理论会有明显的改进.     

Effect of three-phase contact line topology on dynamic contact angles on heterogeneous surfaces

Cassie-Baxter theory has traditionally been used to study liquid drops in contact with microstructured surfaces. The Cassie-Baxter theory arises from a minimization of the global Gibbs free energy of the system but does not account for the topology of the three-phase contact line. We experimentally compare two situations differing only in the microstructure of the roughness, which causes differences in contact line topology. We report that the contact angle is independent of area void fraction for surfaces with microcavities, which correspond to situations when the advancing contact line is continuous. This result is in contrast with Cassie-Baxter theory, which uses area void fraction as the determining parameter, regardless of the type of roughness.     

A new theory for polymer/solvent mixtures based on hard-sphere limit

Based on hard-sphere limit of binary mixtures with different molecular size of components a theory has been developed for calculating activities of solvents in polymer/solvent mixtures. The theory considers various chain configurations for polymer molecules, varying from extended chain to the coiled chain. According to this theory the activity of solvent can be calculated from molecular weights (MWs) and densities as the only input data. The only adjustable parameter in the calculations, is the hard-sphere diameter of polymer, which provides useful criteria for the judgement on the chain configuration of polymer.The activity calculations have been performed for seven binary mixtures of polymer/solvent and compared with experimental data at various temperatures and for a varying range of MWs of polymers.The solvents in the mixtures were both of polar and nonpolar natures. The activity calculations for the same systems were performed by the well-known Flory-Huggins theory. Comparing the results of calculations with those of Flory-Huggins theory indicates that, the proposed theory is able to predict the activities of the solvent with good accuracy.The radius of gyration, excluded volume and interaction parameter for polymer chain have been calculated using the parameter obtained in the new theory. The calculated interaction parameter in the new theory, is interpreted in terms of attraction, repulsion and interchange energy of polymer and solvent in the mixture.     

Spreading kinetics of liquids on liquids

A simple theory is presented for the spreading rate of film forming organic liquids on thick water layers. This theory is an extension of that of Ahmad and Hansen for thin water layers. The theory is compared with experimental data, and fair agreement is obtained. The analogy to longitudinal waves is discussed.     

电解质溶液的分子热力学模型研究进展

"本文从经典溶液理论及半经验模型、近代统计力学理论和分子模拟三大方面阐述了近年来国内外电解质溶液热力学的研究进展。指出电解质溶液的研究已逐渐从经典的溶液理论和半经验模型转向用统计力学理论进行研究, 从电解质的原始模型转向非原始模型。从分子和离子的微观参数出发建立高水平的热力学理论模型, 以预测电解质溶液体系的宏观热力学性质, 是发展的必然趋势。     

Comment on electrolytic friction

Schurr's theory of electrolytic friction neglects hydroelectric coupling. Comparison with Booth's theory shows that this is not a good approximation.     

对结构化学中价键理论教学的若干思考

通过追踪原始文献,分析结构化学中价键理论部分的教学内容,特别是对氧气分子基态电子结构的处理,发现价键理论不仅能够正确解释或预测分子结构,而且对芳香性、铁磁性等化学键本质的描述表现更优.     

Computational studies on the ground and excited states of BrOOBr

In this work, theoretical computations for the ground and excited states of BrOOBr have been performed at high-level ab initio molecular orbital theories. The ground-state geometries of BrOOBr in different forms (trans, cis, and twist form) have been optimized at the couple-cluster CCSD(T) level of theory with cc-pVTZ and aug-cc-pVTZ basis sets, which indicates that at CCSD(T)/cc-pVTZ level of theory, the twist form is 4.96 kcal/mol more stable than the trans form and 10.67 kcal/mol more stable than the cis form; at the CCSD(T)/aug-cc-pVTZ basis set the twist form is 4.33 kcal/mol more stable than the trans form and 9.54 kcal/mol more stable than the cis form. The vertical excitation energies and potential-energy curves for the singlet and triplet low-lying excited states of BrOOBr were calculated at both the complete active space self-consistent-field (CASSCF) level of theory and the multireference internally contracted configuration interaction (MRCI) level of theory. The differences of potential-energy curves at CASSCF and MRCI levels of theory are found for the BrOOBr excited states. At CASSCF level of theory, none of the BrOOBr excited states are bound. However, at MRCI level of theory, all the BrOOBr states studied in this work are bound or slightly bound at the Frank-Condon region. In addition, the scalar relativistic effect and the spin-orbital coupling effect on the vertical excitation energies of the electronic states of BrOOBr were estimated.     

氯化钠水溶液的monte Carlo分子模拟研究

采用MonteCarlo计算机分子模拟方法,研究了氯化钠水溶液在常温和高温情况下粒子的径向分布函数和粒子间各种作用位能的热力学性质。模拟过程采用了NTV正则系综,粒子间的作用能包括离子库仑静电作用,偶极子作用以及色散作用,这些作用构成了电解质溶液的基本框架,模拟结果与微扰理论和平均球近似积分方程理论的预测值进行了比较。     

Influence of adhesion on the sliding and rolling friction

Yet in 1934, one of the authors had developed the molecular friction theory explaining the external friction by dissipation of energy on the molecular unevenness of the bodies in friction. This theory distinctly determines the role of adhesion in the processes of the external sliding friction. The adhesion forces are used in this theory only for explaining deviation from the Amonton's law expressing the proportionality of the friction force to the normal load.

The rolling friction process (in the absence of deformations) represents a process of formation and breakage of adhesion bonds. Using the electron theory as the basis, the mechanism of influence of the electrostatic component of adhesion on the rolling friction is considered, the electrostatic component being attributable to the formation of a double electric layer when solids are in friction, and when its plates are separated as the contact is broken.     

化学计量学的基础算法与应用研究

本文综合讨论了化学计量学的一些基础问题,包括分析信息理论、实验设计与优化、采样理论、分析检测理论、校正理论、分析信号处理、化学模式识别和计算机数字模拟等,并介绍了作者实验室的部分近期工作。     

Time-dependent quasirelativistic density-functional theory based on the zeroth-order regular approximation

A time-dependent quasirelativistic density-functional theory for excitation energies of systems containing heavy elements is developed, which is based on the zeroth-order regular approximation (ZORA) for the relativistic Hamiltonian and a noncollinear form for the adiabatic exchange-correlation kernel. To avoid the gauge dependence of the ZORA Hamiltonian a model atomic potential, instead of the full molecular potential, is used to construct the ZORA kinetic operator in ground-state calculations. As such, the ZORA kinetic operator no longer responds to changes in the density in response calculations. In addition, it is shown that, for closed-shell ground states, time-reversal symmetry can be employed to simplify the eigenvalue equation into an approximate form that is similar to that of time-dependent nonrelativistic density-functional theory. This is achieved by invoking an independent-particle approximation for the induced density matrix. The resulting theory is applied to investigate the global potential-energy curves of low-lying LambdaS- and omega omega-coupled electronic states of the AuH molecule. The derived spectroscopic parameters, including the adiabatic and vertical excitation energies, equilibrium bond lengths, harmonic and anharmonic vibrational constants, fundamental frequencies, and dissociation energies, are in good agreement with those of time-dependent four-component relativistic density-functional theory and ab initio multireference second-order perturbation theory. Nonetheless, this two-component relativistic version of time-dependent density-functional theory is only moderately advantageous over the four-component one as far as computational efforts are concerned.