Mini Liquid‐Liquid Extractor without Moving Parts Based on the Coanda Effect

A mini liquid‐liquid extractor was designed based on a feedback fluidic oscillator. According to the Coanda effect, the designed oscillator with two feedback channels enables good mixing of the aqueous and organic phases. Co‐current liquid‐liquid extraction was performed in the mini extractor, and it was visually observed that the aqueous phase was dispersed into small droplets because of fluidic oscillation and vortex formation. The aqueous phase was more effectively dispersed at the stage near the outlet and with increasing flow. Several tests were performed for evaluating the extraction performance of the extractor using 30 % tributyl phosphate‐kerosene and 3 M HNO₃ solutions as the organic and aqueous phases, respectively. The obtained extraction efficiency was close to the equilibrium efficiency, indicating that this extractor has the potential for liquid‐liquid extraction of hazardous liquids.     

基于全过程设计阶段结构的综合作用探讨

本文从建筑结构教育现状暴露出的现实问题出发,对全过程设计阶段的建筑与结构的综合关系作了详细的探讨,希望读者能对结构在建筑中的作用有进一步的认识,从而提高结构设计的技术内涵和品质。     

The impact of government subsidies and enterprises’ R&D investment: A panel data study from renewable energy in China

In this research, we aim to understand the influence of government subsidies on enterprises’ research and development (R&D) investment behavior, particularly in China’s renewable energy sector. We are also interested in examining how the attributes of enterprise ownership act as a moderating variable for the relationship between government subsidies and R&D investment behavior. Three classical panel data analysis models including the pooled ordinary least squares (OLS) model, the fixed effect model and the random effect model are employed. We find that government subsidies have a significant crowding out influence on enterprises’ R&D investment behavior and that the influence is further moderated by the attributes of enterprise ownership. Moreover, a panel threshold regression model is used to demonstrate how the influence of government subsidies on enterprises’ R&D investment behavior will change when government subsidies increase. Two thresholds, 0.6% and 10.1%, are identified. We recommend that relevant government departments should motivate enterprise R&D investment behavioral intention by increasing subsidies within a certain range. Different attributes of enterprise ownership should also be considered as part of policy reform and re-structuring relating to government subsidies.     

Improved analysis of sinigrin in Ethiopian mustard

An ion‐pair reversed‐phase high‐performance liquid chromatography (HPLC) method was developed for the analysis of sinigrin in Ethiopian mustard (Brassica carinata A. Braun) seed and seed fractions. Separation was compared on several RP‐HPLC columns (Inertsil^® ODS‐4 C₁₈ and ZORBAX^® Eclipse XDB‐C₁₈) with an isocratic eluent containing 100% aqueous (aq.) tetramethylammonium bromide (10 mm , pH 5.0). Sinigrin retention was affected by HPLC variables including the type of ion‐pair reagent, buffer strength and pH, acetonitrile concentration, column temperature and eluent flow rate. Partial validation demonstrated this optimised chromatographic condition to be linear, accurate and precise. Multistage extraction using 70% (v/v) aq. methanol was more efficient than 50% (v/v) aq. acetonitrile. In addition, the matrix effect and recovery rate as well as processing efficiency of the analytical protocol were determined. This method is suitable for high throughput analysis of sinigrin in Ethiopian mustard seed and seed fractions.     

大学生课外体育锻炼效果综合评价及网络构想

为了分析普通高校大学生课外体育锻炼效果，笔者运用文献资料、专家访谈对陕西省部分普通高校大学生参加课外体育锻炼效果的综合评价进行了分析，并根据研究的结果提出大学生课外体育锻炼效果评价的发展趋势和方向。     

Reprint of: Optical properties of wurtzite GaN/AlN quantum dots grown on non-polar planes: The effect of stacking faults in the reduction of the internal electric field

The optical emission of non-polar GaN/AlN quantum dots has been investigated. The presence of stacking faults inside these quantum dots is evidenced in the dependence of the photoluminescence with temperature and excitation power. A theoretical model for the electronic structure and optical properties of non-polar quantum dots, taking into account their realistic shapes, is presented which predicts a substantial reduction of the internal electric field but a persisting quantum confined Stark effect, comparable to that of polar GaN/AlN quantum dots. Modeling the effect of a 3 monolayer stacking fault inside the quantum dot, which acts as zinc-blende inclusion into the wurtzite matrix, results in an additional 30% reduction of the internal electric field and gives a better account of the observed optical features.     

17%唑醚·氟环唑悬乳剂对花生的抗病和保健作用

2012—2013年2年田间药效试验结果表明:17%唑醚·氟环唑悬乳剂有效成分用量为103.2~154.8 g/hm2时,对花生褐斑病具有良好的防治效果,防效在80%以上,且显著增加了花生饱果数和双果数,提高了花生产量,增产率在10%以上。     

Numerical investigation of supercritical LNG convective heat transfer in a horizontal serpentine tube

The submerged combustion vaporizer (SCV) is indispensable general equipment for liquefied natural gas (LNG) receiving terminals. In this paper, numerical simulation was conducted to get insight into the flow and heat transfer characteristics of supercritical LNG on the tube-side of SCV. The SST model with enhanced wall treatment method was utilized to handle the coupled wall-to-LNG heat transfer. The thermal–physical properties of LNG under supercritical pressure were used for this study. After the validation of model and method, the effects of mass flux, outer wall temperature and inlet pressure on the heat transfer behaviors were discussed in detail. Then the non-uniformity heat transfer mechanism of supercritical LNG and effect of natural convection due to buoyancy change in the tube was discussed based on the numerical results. Moreover, different flow and heat transfer characteristics inside the bend tube sections were also analyzed. The obtained numerical results showed that the local surface heat transfer coefficient attained its peak value when the bulk LNG temperature approached the so-called pseudo-critical temperature. Higher mass flux could eliminate the heat transfer deteriorations due to the increase of turbulent diffusion. An increase of outer wall temperature had a significant influence on diminishing heat transfer ability of LNG. The maximum surface heat transfer coefficient strongly depended on inlet pressure. Bend tube sections could enhance the heat transfer due to secondary flow phenomenon. Furthermore, based on the current simulation results, a new dimensionless, semi-theoretical empirical correlation was developed for supercritical LNG convective heat transfer in a horizontal serpentine tube. The paper provided the mechanism of heat transfer for the design of high-efficiency SCV.     

工艺尾气氚测量装置的研制

通过选择装置材料、优化结构及参数,设计制作了有效体积为11.0 mL的测氚电离室,用于工艺尾气中氚含量的测量。用质谱法标定绘制了工作曲线,工作曲线线性范围为0.013 4%～0.168%(体积)。测试表明:装置泄漏率为5.5×10^-7 Pa·m³/s,密封性良好;本底电流为2.98×10^-14A;装置探测下限值为1.35×10^-4 %(体积);变异系数≤1.50%;仪器响应时间≤10 s,响应速度快,测量周期短,满足工艺样品的检测需求。     

Particle-in-cell simulation for effect of anode temperature on discharge characteristics of a Hall effect thruster

Propellant gas flow has an important impact on the ionization and acceleration process of Hall effect thrusters (HETs). In this paper, a particle-in-cell numerical method is used to study the effect of the anode temperature, i.e., the flow speed of the propellant gas, on the discharge characteristics of a HET. The simulation results show that, no matter the magnitude of the discharge voltage, the calculated variation trends of performance parameters with the anode temperature are in good agreement with the experimental ones presented in the literature. Further mechanism analysis indicates that the magnitude of the electron temperature is responsible for the two opposing variation laws found under different discharge voltages. When the discharge voltage is low, the electron temperature is low, and so is the intensity of the propellant ionization; the variation of the thruster performance with the anode temperature is thereby determined by the variation of the neutral density that affects the propellant utilization efficiency. When the discharge voltage is high, the electron temperature is large enough to guarantee a high degree of the propellant utilization no matter the magnitude of the anode temperature. The change of the thruster performance with the anode temperature is thus dominated by the change of the electron temperature and consequently the electron-neutral collisions as well as the electron cross-field mobility that affect the current utilization efficiency.