Optimization of sylvite transformation into arcanite using experimental design methodology

This study is an application of the experimental design methodology for optimizing a potassium sulfate synthesis reaction. The latter is a two‐stage reaction through an intermediate product (Schoenite: K₂SO₄.MgSO₄·6H₂O). To determine optimal experimental conditions of the first stage, we have conducted a fractional factorial design and a central composite one. The optimal conditions of the second stage were determined only by means of a fractional factorial design. Several physico‐chemical techniques were used to implement this study, namely potentiometry, complexometry, gravimetry and X‐ray diffraction. This work has showed that this double decomposition reaction, when performed under the determined optimal conditions, gives good quality potassium sulfate (purity more than 95%) with a maximal yield. Copyright © 2008 John Wiley & Sons, Ltd.     

基于响应面法的半水硫酸钙晶须制备工艺优化

本研究以氯化钙、硫酸为主要原料,采用常压酸化法制备半水硫酸钙晶须.以长径比、长度为主要指标,在单因素实验的基础上,运用响应面法中的Box-Behnken design对反应温度、硫酸浓度、反应时间、搅拌速度进行优化,建立半水硫酸钙晶须制备工艺的数学模型,研究制备的最优工艺条件.结果表明,制备半水硫酸钙晶须的最优工艺条件为:反应温度103℃、硫酸浓度7.4;、反应时间60 min、搅拌速度288 r·min-,得到的晶须样品形貌规整、均一,平均长径比为82.2,φ90为53.3,平均长度为562 μm.     

油菜秸秆对水溶液中Pb(Ⅱ)吸附条件优化与机理的研究

探究油菜秸秆髓芯、外壳、籽荚对水溶液中Pb(Ⅱ)的吸附能力及其吸附机理。以水溶液中Pb(Ⅱ)最大去除率为评价指标,采用响应面法Box-Behnken Design实验来分析溶液pH、Pb(Ⅱ)初始浓度、粒径大小、油菜秸秆各部位投加量和时间因素对油菜秸秆吸附Pb(Ⅱ)的影响程度并建立多元回归模型,优化出最佳吸附条件参数组合;应用吸附动力学、等温吸附线模型来拟合油菜秸秆各部位对Pb(Ⅱ)吸附过程,评价其吸附行为;用红外光谱对吸附水溶液中Pb(Ⅱ)前后的油菜秸秆髓芯、外壳、籽荚进行表征,探讨其基团变化情况。结果表明： 水溶液pH与油菜秸秆髓芯、外壳、籽荚的投加量两个因素是影响油菜秸秆对水溶液中Pb(Ⅱ)去除的关键因素。模型回归决定系数分别是R2_髓芯=0.9664,R2_外壳=0.970 1,R2_籽荚=0.964 9,方程拟合较好,模型可用。油菜秸秆髓芯、外壳、籽荚对Pb(Ⅱ)的吸附行为符合二阶动力学方程与Langmuir等温线模型,对水溶液中Pb(Ⅱ)最大吸附量分别为135.14,78.74和90.09 mg·g-1。通过比较油菜秸秆髓芯、外壳、籽荚吸附水溶液中Pb(Ⅱ)前后红外光谱图发现,油菜秸秆各部位基团(羟基、羧基、酰胺等基团)发生了峰波数位移、强度降低的变化,提示这些基团在吸附水溶液Pb(Ⅱ)过程中发挥重要作用。     

Evaluation of the effective elastic moduli of tetragonal fiber-reinforced composites based on Maxwell’s concept of equivalent inhomogeneity

Maxwell’s concept of an equivalent inhomogeneity is employed for evaluating the effective elastic properties of tetragonal, fiber-reinforced, unidirectional composites with isotropic phases. The microstructure induced anisotropic effective elastic properties of the material are obtained by comparing the far-field solutions for the problem of a finite cluster of isotropic, circular cylindrical fibers embedded in an infinite isotropic matrix with that for the problem of a single, tetragonal, circular cylindrical equivalent inhomogeneity embedded in the same isotropic matrix. The former solutions precisely account for the interactions between all fibers in the cluster and for their geometrical arrangement. The solutions to several example problems that involve periodic (square arrays) composites demonstrate that the approach adequately captures microstructure induced anisotropy of the materials and provides reasonably accurate estimates of their effective elastic properties.     

Central Composite Design for Optimized Extraction of Polysaccharides from Undaria pinnatifida

Response surface methodology was used to optimize the extraction conditions of polysaccharides from Undaria pinnatifida. The effects of three independent variables, extraction time, extraction temperature and ratio of water to raw material were investigated by a central composite design. The experimental data were fitted to a second-order polynomial equation via multiple regression analysis and also examined with the appropriate statistical methods. The adjusted coefficient of determination(R_ADj²) for the model was 0.9171. An optimum extraction yield of 30.78% was obtained when the extraction temperature was 95℃, extraction time was 4.5 h, and the ratio of water to raw material was 35(mL/g). Under these conditions, validation experiments were done and the mean extraction yield of polysaccharides was 30.79%, which was in good agreement with the predicted model value.     

CE‐SDS method development,validation, and best practice—An overview

CE‐SDS has been implemented in the biopharmaceutical industry and is being used for the characterization of therapeutic proteins in most Biological License Applications currently submitted. An overview is presented on the separation mechanism, methodology, and good working practices/best practices. The CE‐SDS platform method development and validation are discussed and typical scientifically and regulatory issues and troubleshooting situations are highlighted.     

ortho‐Oxygenative 1,2‐Difunctionalization of Diarylalkynes under Merged Gold/Organophotoredox Relay Catalysis

Reported herein is an ortho‐oxygenative 1,2‐difunctionalization of diarylalkynes under merged gold/organophotoredox catalysis to access highly functionalized 2‐(2‐hydroxyaryl)‐2‐alkoxy‐1‐arylethan‐1‐ones. Detailed mechanistic studies suggested a relay process, initiating with gold‐catalyzed hydroalkoxylation of alkynes, to generate enol‐ether followed by a key formal [4+2]‐cycloaddition reaction. The successful application of the present methodology was also shown for the synthesis of benzofurans.     

Synthesis and characterization of a novel polyurethane/polypyrrole‐p‐toluenesulfonate (PU/PPy‐pTS) electroactive nanofibrous bending actuator

Electroactive actuators based on conductive polymers currently have attracted a great deal of attention. In this study, a nanofibrous structure of polypyrrole (PPy) was used to fabricate an electroactive bending actuator. For this purpose, polyurethane/PPy (PU/PPy) nanofibrous bending actuator was fabricated through the combined use of electrospinning and in‐situ chemical polymerization. The response surface methodology (RSM) was considered to find the optimal electrospinning conditions for producing PU nanofibers with the minimum diameter. The in‐situ chemical polymerization method was then used to prepare a conductive layer of PPy on the surface of optimum electrospun nanofibers with p‐toluenesulfonate (pTS) as the dopant. The coated nanofibers were used in the fabrication of PU/PPy‐pTS nanofibrous bending actuator. The morphology and electrical, thermal, electrochemical, and electrochemomechanical properties of the fabricated actuator were investigated. By using optimum conditions of electrospinning, PU nanofibers were obtained with a diameter of 221 nm. The results showed that the produced PU/PPy‐pTS nanofibers enjoy good thermal stability and have an electrical conductivity of about 276.34 S/cm. The obtained cyclic voltammetric and dynamo‐voltammetric responses showed that the dominant mechanism of actuation in the fabricated PU/PPy‐pTS nanofibrous actuator is the exchange of perchlorate anions with a partial exchange of lithium cations in 1M lithium perchlorate electrolyte solution. The fabricated actuator was capable of undergoing 141° reversible angular displacement during a potential cycle. The results demonstrated that, given high porosity, large specific surface area, flexibility, and desirable electrical properties, PU/PPy nanofibrous electroactive actuator provides a lot of potential for developing artificial muscle applications.     

Modelling of high-pressure dense diesel sprays with adaptive local grid refinement

An Eulerian–Lagrangian fluid dynamics model simulating the development of dense liquid plumes formed during injection of fuels against compressed air is described and assessed against experimental data. The numerical model employs an adaptive local grid refinement methodology combined with a calculation procedure distributing the mass, momentum and energy exchanged between the liquid and gaseous phases in the numerical cells found in the vicinity of the moving droplets. The use of appropriate weighting functions resolves numerical as well as physical problems realised when the interaction volume available between the two phases is limited to the cell-containing parcel, whose volume may become comparable to that of the dispersed phase. Calculation of ‘virtual’ cell properties provide better estimates for the flow variables realised by the droplets crossing cells in the wake of those upstream and allows for larger time steps to be employed in the solution of the carrier phase conservation equations. The results suggest that the proposed methodology offers significant improvements compared to the standard Lagrangian one frequently adopted in simulation of combustion systems, without the need to use Eulerian flow models in dense spray regions.