Principles of Surface Potential Estimation in Mixed Electrolyte Solutions:Taking into Account Dielectric Saturation

The dielectric properties between in-particle/water interface and bulk solution are significantly different, which are ignored in the theories of surface potential estimation. The analytical expressions of surface potential considering the dielectric saturation were derived in mixed electrolytes based on the nonlinear Poisson-Boltzmann equation. The surface potentials calculated from the approximate analytical and exact numerical solutions agreed with each other for a wide range of surface charge densities and ion concentrations. The effects of dielectric saturation became important for surface charge densities larger than 0.30 C/m\begin{document}$ ^2 $\end{document}. The analytical models of surface potential in different mixed electrolytes were valid based on original Poisson-Boltzmann equation for surface charge densities smaller than 0.30 C/m\begin{document}$ ^2 $\end{document}. The analytical model of surface potential considering the dielectric saturation for low surface charge density can return to the result of classical Poisson-Boltzmann theory. The obtained surface potential in this study can correctly predict the adsorption selectivity between monovalent and bivalent counterions.     

Simulation of proppant transport at intersection of hydraulic fracture and natural fracture of wellbores using CFD-DEM

Proppants transport is an advanced technique to improve the hydraulic fracture phenomenon, in order to promote the versatility of gas/oil reservoirs. A numerical simulation of proppants transport at both hydraulic fracture (HF) and natural fracture (NF) intersection is performed to provide a better understanding of key factors which cause, or contribute to proppants transport in HF–NF intersection. Computational fluid dynamics (CFD) in association with discrete element method (DEM) is used to model the complex interactions between proppant particles, host fluid medium and fractured walls. The effect of non-spherical geometry of particles is considered in this model, using the multi-sphere method. All interaction forces between fluid flow and particles are considered in the computational model. Moreover, the interactions of particle–particle and particle–wall are taken into account via Hertz–Mindlin model. The results of the CFD-DEM simulations are compared to the experimental data. It is found that the CFD-DEM simulation is capable of predicting proppant transport and deposition quality at intersections which are in agreement with experimental data. The results indicate that the HF–NF intersection type, fluid velocity and NF aperture affect the quality of blockage occurrence, presenting a new index, called the blockage coefficient which indicates the severity of the blockage.     

具有单晶到单晶转化的Cu(Ⅰ)配合物的发光性质

选用2-(N，N-双(二苯基膦基甲基))胺基吡啶(bdppmapy)为膦配体、二吡啶并[3，2-a∶2''，3''-c]吩嗪(dppz)为氮配体、[Cu (CH₃CN)₄]BF₄为铜盐，在常温下进行反应，制备了3种新型Cu(Ⅰ)配合物，分别为[Cu (dppz)(bdppmapy)]₂(BF₄)₂·H₂O (CuBF₄-1)、[Cu (dppz)(bdppmapy)]BF₄(CuBF₄-2)和[Cu (dppz)(bdppmapy)]BF₄(CuBF₄-3)。获得了CuBF₄-1和CuBF₄-3的单晶，发现了单晶到单晶转化过程的现象，并探究了溶剂分子的存在对配合物结构和光物理性能的影响。通过单晶X射线衍射确定配合物CuBF₄-1和CuBF₄-3的结构，使用粉末X射线衍射(PXRD)、红外光谱(IR)和核磁共振氢谱/磷谱(¹H/³¹P NMR)对合成的3个配合物进行结构表征。对配合物进行紫外可见吸收光谱(UV-Vis)、荧光光谱、荧光寿命及量子产率等光物理性质的表征和分析，比较了配合物发光性质的差异，探讨了溶剂分子对配合物结构和光物理性质的影响规律。太赫兹时域光谱对配合物的研究提供了帮助。     

Tritium and stable isotope content variation in precipitation at Hongseung: West Korea Region

Journal of Radioanalytical and Nuclear Chemistry - Tritium and stable isotopes contents in precipitation were analyzed on a monthly base at Hongseung which was located middle west of Korea...     

C-14 and H-3 contents in the groundwater around radioactive repository site in Korea

The contents of H-3 and C-14 in groundwater and surface waters around low and medium-level atomic waste repository site in Korea were determined. The concentrations of C-14 were in the range 0.186–0.287 Bq/L. The H-3 concentration of the groundwaters and surface waters were <0.06–5.75 and 1.22–4.74 Bq/L. The average H-3 contents of west, north and south direction were 1.18 ± 0.12, 1.11 ± 0.78 and 2.85 ± 2.66. H-3 and C-14 concentrations in the south direction were relatively higher than west and north direction samples. The surface waters sampled from catchment were four times higher than average H-3 concentration in precipitation. The concentrations of H-3 and C-14 within 5 km area samples were much higher than other samples.     

Simultaneous hyperaccumulation of arsenic and antimony in Cretan brake fern: Evidence of plant uptake and subcellular distributions

Arsenic (As) and antimony (Sb) show similar chemical properties and often present together in sulfide ores. Currently, phenomenon of co-contamination of As and Sb at some sites of the world has been increasingly emerged. The present study was conducted to explore the potential of Pteris cretica L. (Cretan brake fern), an arsenic (As) hyperaccumulator, to simultaneously accumulate As and Sb under hydroponic conditions. Arsenic was imposed at medium and high levels of 5 mg L^− 1 and 20 mg L^− 1, while Sb was imposed either single or co-presence with As at medium and high levels of 10 mg L^− 1 and 20 mg L^− 1, with no As and Sb addition as the control. The single and interactive effects of As and Sb on their uptake and subcellular distributions were analyzed. Cretan brake fern could accumulate high concentrations of As and Sb, with the highest concentrations of As and Sb been recorded as 1677.2 mg kg^− 1 and 1516.5 mg kg^− 1 in the fronds, respectively. Arsenic and Sb were found mainly in cytosol, while less in cell wall and cytoplasmic organelles. Sb uptake by Cretan brake fern was enhanced with increasing As levels, which was accompanied with an increase of Sb but a decrease of As in cytosol fractions. Arsenic uptake was slightly enhanced whereas suppressed when Sb was co-present in a medium and high level, respectively; however, in both conditions, As was found to be decreased in cytosol of the above ground parts as fronds and stems of Cretan brake fern. The results demonstrate Cretan brake fern can simultaneously hyperaccumulate As and Sb, thus is valued in phytoremediation of As and Sb co-contamination.     

Continuous measurement of ozone in air by chemiluminescence using ndigo-5,5′-disulphonate

Gas-phase ozone was continuously measured by using the chemiluminescent reaction between indigo-5,5′-disulphonate and ozone. A detection limit of 0.4 ppb (v/v) was obtained using a reaction cell of 0.7 ml at a sampling rate of 15.0 ml min^?1. The method was applied to the monitoring of ozone in the atmosphere.