Study of the influence of porosity on the radon emanation coefficient in different building material samples by combining the SSNTD technique with Monte Carlo simulations

Radon alpha-activities per unit volume have been measured inside and outside different building material samples by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD). Radon emanation coefficients of the studied building materials have been evaluated. The porosities of the building material samples studied have been determined by using a Monte Carlo calculational method adapted to the experimental conditions and compared with data obtained by the Archimedes's method. The influence of the building material porosity on the radon emanation coefficient has been investigated.     

Polarographic study of simple and mixed-ligand complex formation

Theoretical, experimental and statistical aspects of the polarographic method applied to simple and mixed-ligand complex formation have been studied. Some misunderstandings and erroneous interpretations have been clarified according to experimental results obtained with several systems. A criterion for establishing the number of complex species present in a simple system is proposed. For the first time the polarographic method has been applied to a mixed-ligand complex system where fourteen species co-exist.     

铟(Ⅲ)-向红菲啰啉络合物的吸附伏安法研究

运用1 5次微分伏安法 ,常规溶出伏安法及循环伏安法研究了铟(Ⅲ) -向红菲啉络合物在汞电极上的电化学行为 ,讨论了络合物的形成机理及条件 ,建立了测试痕量铟的新方法 ,运用该法对样品中痕量铟进行了测试 ,结果令人满意。     

硫酸氢钾(KHSO4,A.R.)的低温热容和热化学性质

硫酸氢钾（ＫＨＳＯ4,Ａ．Ｒ）是一种重要的无机化工原料。在化肥工业中,它是生产复合肥硫酸铵钾（ＫＮＨ４ＳＯ４）的主要原料之一。为了找到工业上生产复合肥硫酸铵钾的最佳工艺条件,提高其产率和经济效益,并且开发其新的应用领域,迫切需要该化合物准确的热力学数据作为理论分析的依据。 硫酸氢钾的导热系数,溶解度,熔点等部分热物性数据［１－３］已有报道,但是,迄今为止,文献中未见到它的低温热容和热分解过程的详细报道。本文用精密自动绝热热量计直接测定了硫酸氢钾在７８－３７３Ｋ温区的热容,并且将实验热容值用最小二乘…     

Optimisation and comparison of microwave-assisted extraction and Soxhlet extraction for the determination of polychlorinated biphenyls in soil samples using an experimental design approach

Optimisation of microwave-assisted extraction (MAE) for the extraction of polychlorinated biphenyls (PCBs) from soil samples has been accomplished using an experimental design approach. Variables studied have been: percentage of acetone (v/v) in an acetone:n-hexane mixture, solvent volume, extraction time, microwave power and pressure inside the extraction vessel. Five samples of a certified soil (CRM 481) have been extracted under the optimum conditions of the developed method and the results have been compared to those obtained by Soxhlet extraction. Good recoveries (>95%) have been obtained for all the PCBs studied. All extracts have been analysed by gas chromatography/mass spectrometry (GC/MS) and an optimum determination method for the electron impact mass spectrometric (EIMS) has also been developed.     

硫酸氢钾(KHSO4,A. R. )的低温热容和热化学性质

The heat capacities of KHSO₄ crystal (A.R.) have been measured with a small sample precision automated adiabatic calorimeter over the temperature range from 78 to 373 K.The experimental results have shown that there is no phase transition or thermal anomaly in this temperature region for the present crystal.The experimental heat-capacity data have been fitted to a smoothed curve with the aid of the least square method.In addition, the process of the thermal decomposition has been studied by TG analysis.     

盐卤硼酸盐化学XXX-MgO·2B_2O_3-18%MgCl_2-H_2O过饱和溶液结晶动力学

对ＭｇＯ·２Ｂ_２Ｏ_３－１８％ＭｇＣｌ_２－Ｈ_２Ｏ过饱和溶液在不同温度条件下的结晶动力学过程进行测定,给出结晶动力学方程。析出固相采用Ｘ－射线粉末衍射、红外光谱和热分析进行物相鉴定。提出使用结晶法合成章氏硼镁石的新方法。     

Theoretical study on the hydroxide ion addition to esters

By means of the MINDO/3 method the potential surfaces for the method of attack of hydroxide ion on methyl formate and methyl oxalate anion have been studied. In the case of the neutral ester three competitive mechanisms have been found, in good agreemen with experimental results in the gas phase.     

用平均场近似研究液晶分子结构与清亮点的关系

液晶的平均场理论假设每个液晶分子都是处在其它周围所有分子的平均作用势场中, 而不考虑该分子与周围各个分子之间的单独关联, 一个分子所感受到的分子场就是所有其它分子给予这个分子的作用场对位置和对取向的平均值. 当周围分子不是完全有序排列时, 其混乱程度可以用序参量S表示(S≤1), 中央一个分子受的势能为－Sg(θ). 其中g(θ)是在排列整齐的平均场中该分子的势能函数的负值. 在此基础上, 可以解一个关于序参量和温度的积分方程, 求出清亮点. 本文采用Gay-Berne势模拟液晶分子的双体势, 用分子力学UFF方法优化液晶分子(二环辛烷和硼笼的衍生物)的单体和双体的构型和能量, 从而获得Gay-Berne势的参数, 得到液晶的清亮点. 计算结果与实验基本一致.     

A theoretical investigation of the preferred conformations of glutathione and its constituent amino acid residues

The preferred conformations of the tripeptide glutathione have been investigated by performing quantum mechanical calculations using the PCILO method. A series of model compounds representing fragments of the tripeptide has been studied as well as the complete molecule. The results are compared with the available experimental data.     

中心原子对Keggin结构杂多钼酸盐氧化还原特性的影响

用电化学方法研究了Keggin结构的砷钼酸盐、磷钼酸盐和硅钼酸盐的氧化还原性质.由实验结果得出中心原子砷、磷和硅对该类杂多钼酸盐氧化还原性质的影响规律。     

Investigations of Retention Rule in Reversed-Phase High Performance Liquid Chromatography——Theoretical Consideration of Retention Convergence and Experimental Verification

This paper studied the effect of different chromatographic parameters in RP-HPLC (for example,composition of mobile phase, temperature, number of carbon atoms within the solute molecules, solvent molecules and alkyl ligand on bonded phase surface) on the retention convergence based on the displacement adsorption multi-interaction model,and derived a few retention convergent equations by using thermodynamic method,which have been verified by a great deal of experimental data of homologous series.Moreover,we have developed a general method, which can calculate the coordinate values of various retention convergent points by computer directly from experimental data,and the results predicted are in good agreement with that obtained by using plotting method.     

Simultaneous separation of copper, cadmium and cobalt from sea-water by co-flotation with octadecylamine and ferric hydroxide as collectors

A method is proposed for the simultaneous quantitative separation of traces ofCu(II), Cd(II) and Co(II) from sea-water samples by means of the co-flotation (adsorbing colloid flotation) technique with ferric hydroxide as co-precipitant and octadecylamine as collector. The experimental parameters have been studied and optimized. The drawbacks arising from the low solubility of octadecylamine and the corresponding sublates in water have been avoided by use of a 6M hydrochloric acid-MIBK-ethanol (1:2:2 v v ) mixture. The results obtained by means of the proposed method have been compared with those given by the usual ammonium pyrrolidine dithiocarbamate/MIBK extraction method.     

Electronic absorption spectrum of perylene radical cation trapped in boric acid film

A detailed spectroscopic analysis of the electronic absorption spectrum of the perylene radical cation, produced in a boric acid film by photo-oxidation is reported. To interpret the experimental spectrum, the electronic energy levels and oscillator strengths have been calculated using the Pariser—Parr molecular orbital method with limited configuration interaction. The effect of variation of solute concentration and irradiation time of the films has also been studied. It is found that the agreement between experimental and theoretical results in excellent.     

热动力学对比参量法 --简单级数反应

根据化学反应动力学和热动力学基本理论, 建立了简单级数反应的热动力学对比参量方程, 提出了一种新的热动力学研究法--对比参量法. 利用该法可以从一张热谱图上同时解析出化学反应的速率常数、半衰期和热动力学体系的冷却常数. 实验结果验证了方法的正确性.     

连续旋转环状色谱的数学模型参数分析

连续旋转环状色谱用数学模型模拟时,模拟结果的精确度和所采用参数的“灵敏”程度有关。为此,探讨了相平衡常数、相间传质系数、弥散返混系数等对色谱峰质量浓度最高点位置角度（保留值）、分离度、峰宽和产率等参数的灵敏度并对它们逐一进行了分析。认为相平衡关系对分离效果最为敏感。筛选吸附量大、选择性好的吸附剂是改进操作效果的最佳途径。     

A Combined Experimental and Theoretical Study of Nitrofuran Antibiotics: Crystal Structures,DFT Computations,Sublimation and Solution Thermodynamics

Single crystal of furazolidone (FZL) has been successfully obtained, and its crystal structure has been determined. Common and distinctive features of furazolidone and nitrofurantoin (NFT) crystal packing have been discussed. Combined use of QTAIMC and Hirshfeld surface analysis allowed characterizing the non-covalent interactions in both crystals. Thermophysical characteristics and decomposition of NFT and FZL have been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and mass-spectrometry. The saturated vapor pressures of the compounds have been measured using the transpiration method, and the standard thermodynamic functions of sublimation were calculated. It was revealed that the sublimation enthalpy and Gibbs energy of NFT are both higher than those for FZL, but a gain in the crystal lattice energy of NFT is leveled by an entropy increase. The solubility processes of the studied compounds in buffer solutions with pH 2.0, 7.4 and in 1-octanol was investigated at four temperatures from 298.15 to 313.15 K by the saturation shake-flask method. The thermodynamic functions of the dissolution and solvation processes of the studied compounds have been calculated based on the experimental data. Due to the fact that NFT is unstable in buffer solutions and undergoes a solution-mediated transformation from an anhydrate form to monohydrate in the solid state, the thermophysical characteristics and dissolution thermodynamics of the monohydrate were also investigated. It was demonstrated that a combination of experimental and theoretical methods allows performing an in-depth study of the relationships between the molecular and crystal structure and pharmaceutically relevant properties of nitrofuran antibiotics.     

Structure electronique de derives sulfures—II : Spectres electroniques du cation dithiolylium-1,2 et de ses derives de monosubstitution

The electronic spectra of the 1,2-dithiolium cation and of four monosubstituted derivatives have been studied by CNDO/S method, extended to the third period with inclusion of 3d orbitals. Calculated effects of a substitution by a methyl or a phenyl group are in good agreement with experimental data.     

Precision in 14 MeV neutron activation analysis

The errors of analysis due to the different parameters involved in 14 MeV neutron activation analysis method are studied. Formulae to calculate these erros have been developed when possible. Otherwise they have been evaluated for special experimental situations. Special cases where some parameters become critical, as far as precision is concerned, have been mentioned.     

The charge distribution of iron complexes studied by XPS,Mössbauer spectroscopy,and SCC-MO calculations

A series of iron complexes has been studied by XPS and Mössbauer spectroscopy. Atomic charges and iron atom populations have been estimated from the experimental results and compared with iterative extended Hückel (IEH) calculations as well as with calculations based on a modified form of this method (MIEH).