Modeling of Mechanical Properties of Polymeric Systems with Branching/Crosslinking,Particularly Their Mechanical Resistence and Stability

A theoretical method for the estimation of mechanical characteristics of polymeric structures is proposed. This method uses the statistical polymer method for modeling branched/crosslinked structures. The proposed method is utilized for the estimation of mechanical resistance and stability of microporous polymeric materials. An engineering method for the evaluation of mechanical stability and resistance of polymeric materials is derived.     

Exposé d'une méthode de détermination des orbitales virtuelles pour les interactions de configurations. Application à l'etat fondamental de l'atome de béryllium

A method for the determination of the virtual orbitals for configuration interaction is described. This method is a generalization of the one used by Watson in 1960 for the ground state of the beryllium atom. The important point in the method is to complete the set of functions used successively. As an illustration the method is applied to the ground state of the beryllium atom. The method seems to be efficient.     

Theoretical Modeling of Mechanical Resistance and Stability and Related Characteristics of Polymeric Systems with Branching/Cross-Linking

A theoretical (thermodynamic) method for the estimation of mechanical characteristics of polymeric systems is proposed. This method uses the statistical polymer method for modeling of branched/cross-linked structures. The weak interaction between macromolecules is modeled in the approach of their mutual interpenetration. The proposed method is used for the estimation of mechanical resistance and stability of microporous polymeric materials. An engineer method for the evaluation of mechanical stability and resistance of polymeric materials is derived.     

A combination of the tree-code and IPS method to simulate large scale systems by molecular dynamics

An IPS/Tree method which is a combination of the isotropic periodic sum (IPS) method and tree-based method was developed for large-scale molecular dynamics simulations, such as biological and polymer systems, that need hundreds of thousands of molecules. The tree-based method uses a hierarchical tree structure to reduce the calculation cost of long-range interactions. IPS/Tree is an efficient method like IPS/DFFT, which is a combination of the IPS method and FFT in calculating large-scale systems that require massively parallel computers. The IPS method has two different versions: IPSn and IPSp. The basic idea is the same expect for the fact that the IPSn method is applied to calculations for point charges, while the IPSp method is used to calculate polar molecules. The concept of the IPS/Tree method is available for both IPSn and IPSp as IPSn/Tree and IPSp/Tree. Even though the accuracy of the Coulomb forces with tree-based method is well known, the accuracy for the combination of the IPS and tree-based methods is unclear. Therefore, in order to evaluate the accuracy of the IPS/Tree method, we performed molecular dynamics simulations for 32,000 bulk water molecules, which contains around 10(5) point charges. IPSn/Tree and IPSp/Tree were both applied to study the interaction calculations of Coulombic forces. The accuracy of the Coulombic forces and other physical properties of bulk water systems were evaluated. The IPSp/Tree method not only has reasonably small error in estimating Coulombic forces but the error was almost the same as the theoretical error of the ordinary tree-based method. These facts show that the algorithm of the tree-based method can be successfully applied to the IPSp method. On the other hand, the IPSn/Tree has a relatively large error, which seems to have been derived from the interaction treatment of the original IPSn method. The self-diffusion and radial distribution functions of water were calculated each by both the IPSn/Tree and IPSp/Tree methods, where both methods showed reasonable agreement with the Ewald method. In conclusion, the IPSp/Tree method is a potentially fast and sufficiently accurate technique for predicting transport coefficients and liquid structures of water in a homogeneous system.     

Coherent switching with decay of mixing: an improved treatment of electronic coherence for non-Born-Oppenheimer trajectories

The self-consistent decay-of-mixing (SCDM) semiclassical trajectory method for electronically nonadiabatic dynamics is improved by modifying the switching probability that determines the instantaneous electronic state toward which the system decoheres. This method is called coherent switching with decay of mixing (CSDM), and it differs from the previously presented SCDM method in that the electronic amplitudes controlling the switching of the decoherent state are treated fully coherently in the electronic equations of motion for each complete passage through a strong interaction region. It is tested against accurate quantum mechanical calculations for 12 atom-diatom scattering test cases. Also tested are the SCDM method and the trajectory surface hopping method of Parlant and Gislason that requires coherent passages through each strong interaction region, and which we call the "exact complete passage" trajectory surface hopping (ECP-TSH) method. The results are compared with previously presented results for the fewest switches with time uncertainty and Tully's fewest switches (TFS) surface hopping methods and the semiclassical Ehrenfest method. We find that the CSDM method is the most accurate of the semiclassical trajectory methods tested. Including coherent passages improves the accuracy of the SCDM method (i.e., the CSDM method is more accurate than the SCDM method) but not of the trajectory surface hopping method (i.e., the ECP-TSH method is not more accurate on average than the TFS method).     

Pharmaceutical analysis of some tranquillizers and antidepressants with iodine monochloride

A titrimetric method for the evaluation of some tranquillizers and antidepressants is proposed. The method is based on the oxidation of these drugs by iodine monochloride, in strong acid medium, the iodine liberated being titrated with potassium iodate by the Andrews method. The proposed method is applied successfully for the determination of 9 phenothiazines, 1 thioxanthene, 2 acid hydrazides and 1 dibenzazepine containing a double bond (Opipramol). Tablets, solutions for injection, and drops are also determined by the proposed method. The mechanism of oxidation for each species is suggested and the results obtained agree with these suggestions. Some official and non-official methods for the evaluation of the drugs have been compared with the iodine monochloride method, which is found to be superior in specificity, sensitivity and speed.     

Development of effective Stokesian dynamics method for ferromagnetic colloidal dispersions (cluster-based Stokesian dynamics method)

We have developed a new Stokesian dynamics (SD) method for nondilute colloidal dispersions, which enables us to reduce drastically the computation time. To verify the validity of the present method, which is called the "cluster-based SD method," three-dimensional simulations of a ferromagnetic colloidal dispersion have been carried out for a simple shear flow. The correlation function and viscosity have been evaluated to compare the results obtained by the present method with those obtained by the ordinary SD method and by the method of ignoring hydrodynamic interactions between particles. The results obtained here are summarized as follows. The transient properties from an initial state obtained by the present method agree well with those obtained by the ordinary method, even if a radius r(clstr), which defines the cluster formation, is taken as a small value such as r(clstr)=1.2d (d is the particle diameter). Also, the equilibrium properties such as the pair correlation function and viscosity obtained by the present cluster-based method are in satisfactory agreement with those obtained by the ordinary SD method. Furthermore, the cluster-based method drastically reduces the computation time to about one-fourteenth to one-seventieth that of the ordinary method. It is clear from these results that the cluster-based SD method is significantly superior to the ordinary SD method for ferromagnetic colloidal dispersions for which a large model system such as N=1000 or 10,000 is indispensable in simulations.     

The Law of Mixtures method for multivariate calibration

The Law of Mixtures (LM) method is a new so-called topological method for multivariate calibration. It is shown to be a very good method to predict the response for new objects that are inside the convex hull determined by the calibration data set. A method is also proposed for those that are outside the convex hull.     

Determination of all platinum-group elements in mantle derived xenoliths by neutron activation analysis with NiS fire-assay preconcentration

A modified NiS fire-assay neutron activation method is developed for the determination of all platinum-group elements (PGEs) in mantle-derived xenoliths. This method is characterized by sub-ppb detection limits, <0.1~0.002 ppb procedural blanks and 7~15% analytical precision for PGEs. Analyses of PGE standard rocks indicate that this modified NiS fire-assay neutron activation method is as reliable as the method previously proposed for a large scale of samples. The capability of the method for the measurement of PGEs in the upper mantle is also illustrated by some exciting results obtained from mantle-derived xenoliths of Eastern China.     

Dynamical dimer method for the determination of transition states with ab initio molecular dynamics

A dynamical formulation of the dimer method for the determination of transition states is presented. The method is suited for ab initio molecular dynamics using the fictitious Lagrangian formulation. The method has been applied to the conrotatory ring opening of chlorocyclobutadiene, an example, where the application of the drag method is problematic.     

双指示物质动力学分析法研究Ⅰ.锰(Ⅱ)-乙二胺四乙酸二钠-铬(Ⅵ)催化体系

本文报道了双指示物质测定痕量锰的新催化光度法, 探讨了该方法的理论基础,确定了催化体系的适宜反应条件.本办法灵敏度比单指示物质法高6.4倍,用于测定谷物样品中锰.     

冷焰ICP-MS法测定高纯稀土氧化物中铁和钙的研究

用冷焰技术对高纯稀土氧化物中Ｆｅ和Ｃａ的分析方法进行了研究。估算了测定范围和检出限,探讨了内标元素对基体影响的校正作用,测定了加标回收率,对半定量法（ＴＱ）和定量法（ＱＡ）的结果作了比较。表明冷焰条件下,痕量Ｆｅ的测定是可行的,但Ｃａ的测定结果仍不理想;ＱＡ法明显优于ＴＱ法。     

Reverse Schreinemakers Method for Experimental Analysis of Mixed-Solvent Electrolyte Systems

A method based on Schreinemakers’s tie-line theory of 1893 is derived for determining the composition and phase amounts in solubility experiments for multi-solvent electrolyte systems. The method uses the lever rule in reverse compared to Schreinemakers’s wet residue method, and is therefore called the reverse Schreinemakers (RS) method. The method is based on simple mass balance principles similar to the wet residues method. It allows for accurate determination of the mixed-solvent phase composition even though part of the solvent may precipitate as complexes between solvent and salt. Discrepancies from determining the composition of salt mixtures by pH titration are discussed, and the derived method significantly improves the obtained result from titration. Furthermore, the method reduces the required experimental work needed for analysis of phase composition. The method is applicable to multi-solvent systems and may be used for the determination of solid-phase compositions, similar to Schreinemakers’s original “rest” method. An example calculation is presented for the Na₂CO₃-NaHCO₃-MEG-H₂O system.     

Computer-assisted optimization of selectivity (mobile phase,pH, and ion concentration) in high-perfomance liquid chromatography

A computer-assisted method is presented for optimization of mobile phase composition in reverse-phase and normal-phase HPLC. The method is based on window diagrams, but only three preliminary tests are required. The method is successfully applied to two examples and there is good agreement between predicted and experimental results. Optimal values for ion concentration and pH in ion chromatography from a published optimization method are compared to values calculated using the computer-assisted method presented in this paper. The same results are obtained, but the method presented here is simpler and faster than previously published one.     

按独立组元计算复杂化学平衡的方法

本文通过分析独立组元的本质,提出了一个按独立组元来计算复杂化学平衡的方法。这个方法中的未知数和方程数比现有的自由能最小化法、质量作用方程组的方法和反应进度的方法中的未知数和方程数显著减少,因而计算过程大为简化。例如,对于计算一个由3个元素10个组元组成的复杂化学平衡体系来说,若采用其它方法须用电子计算机,而采用独立组元法仅须使用袖珍可编程序计算器即可完成。本文叙述了独立组元法的基本原理和具体方法,并根据理论分析和计算实践,将独立组元法与其它方法的优劣作了对比。     

从特性粘数和GPC图谱获得数均分子量的新方法

本文提出了从未知K和a的样品的特性粘数和GPC图谱计算数均分子量的新方法。该法对窄分布或宽分布的样品都适用,并用不同分子量和分子量分布的样品进行了验证,和已知K和a的计算值进行比较,得到非常满意的结果。该法是计算M_n的近似解法,但计算简便。     

金属和试剂分别过量时测定不同配合物组成的新方法

金属和试剂分别过量时测定不同配合物组成的新方法何锡文,唐志新,张贵珠,杨万龙,于贵英,史慧明（南开大学化学系,天津,３０００７１）关键词配合物组成,穷举法,光度分析本文用穷举法推导了一种新的数学模型,该法不需要假定配合比,就能测定当试剂和金属分别过量...     

pH计检定仪期间核查方法

介绍pH计检定仪的4种期间核查方法:传递比较法、多台对比法、留样测量法、实验室间比对法。传递比较法能直接反应pH计检定仪的变化,适用于已建立pH计检定仪检定装置的单位;多台对比法与留样测量法方便、快捷,可操作性强,适合大多数单位进行pH计检定仪的期间核查;实验室间比对法对设备要求较低,但需要协调的单位较多,周期较长,费用较高,实用性差。     

净叶宝乳油中水分含量的气相色谱法测定

采用气相色谱法在GDX-102色谱柱上分离和测定净叶宝系列乳油中的水分;该法操作简便、快速、准确可靠且对人体和环境安全;对同一试样的6次平行独立测定的标准偏差为0.017%,相对标准偏差为3.5%,加标回收率在98%以上。