Monte Carlo simulations of a coarse grained model for an athermal all-polystyrene nanocomposite system

The structure of a polystyrene matrix filled with tightly cross-linked polystyrene nanoparticles, forming an athermal nanocomposite system, is investigated by means of a Monte Carlo sampling formalism. The polymer chains are represented as random walks and the system is described through a coarse grained Hamiltonian. This approach is related to self-consistent-field theory but does not invoke a saddle point approximation and is suitable for treating large three-dimensional systems. The local structure of the polymer matrix in the vicinity of the nanoparticles is found to be different in many ways from that of the corresponding bulk, both at the segment and the chain level. The local polymer density profile near to the particle displays a maximum and the bonds develop considerable orientation parallel to the nanoparticle surface. The depletion layer thickness is also analyzed. The chains orient with their longest dimension parallel to the surface of the particles. Their intrinsic shape, as characterized by spans and principal moments of inertia, is found to be a strong function of position relative to the interface. The dispersion of many nanoparticles in the polymeric matrix leads to extension of the chains when their size is similar to the radius of the dispersed particles.     

Variable chemical species and thermo-diffusion Darcy–Forchheimer squeezed flow of Jeffrey nanofluid in horizontal channel with viscous dissipation effects

This research communicates the applications of thermos-diffusion effect associated to the squeezing flow of Jeffrey nanofluid due to horizontal channel. The problem presents the applications of inertial effects by following the Darcy–Forchheimer flow. Moreover, the effects of viscous dissipation and activation energy phenomenon has been discussed. The dimensionless attention of problem is retained. The shooting technique is implemented to present the numerical computations. The numerical validation of results is reported. The essential assessment of physical flow parameters is studied. The numerical outcomes are presented for heat and mass transfer phenomenon. It is observed that presence of inertial forces control to velocity flow in the regime. The enhancing contribution of thermal and concentration rate is noted for inertial constant.     

气相色谱内标法测定皮革中五氯酚残留量不确定度评估

采用气相色谱内标法测定皮革中五氯酚残留量,对整个测量过程的不确定度来源进行了分析,并对不确定度各个分量进行了评估和合成,结果显示,样品重复性测量不确定度分量对总不确定度的贡献最大。当五氯酚测定结果为1.021 mg/kg时,扩展不确定度为0.056 mg/kg。按照相关计量规范要求,给出了五氯酚测量结果不确定的表达式。     

稻壳纤维的柱层析性能研究

试验了稻壳纤维作为柱层析介质的性能,并制成亲和层析介质经脂肪酶。结果表明稻壳纤维层析过程为化学物理混合吸附过程,亲和层析性能良好,层析可将脂肪酶纯化２倍,回收率达８１．６％。适合较大规模层析分离。     

植物甾醇女士访谈录

通过采访植物甾醇女士,了解植物甾醇家族的成员、基本性质、生理功能等。揭示了其降低胆固醇、减肥、美容功能的基本原理,了解了抗癌机理,介绍了植物甾醇在食物中的分布、人体吸收困难的原因及对策,为人类健康生活提出膳食建议。     

Electrochemistry of the bis(1,4,7-triazacyclodecane) cobalt(III) complex and its role in the catalytic reduction of hydrogen

The electrochemistry of the bis(1,4,7-triazacyclodecane) cobalt(III) complex at a mercury electrode, HMDE, in aqueous Britton–Robinson buffer solutions was investigated using cyclic voltammetry, double-potential-step chronoamperometry and chronocoulometry. The cyclic voltammetric data were analyzed by digital simulation to confirm and to measure the heterogeneous and homogeneous parameters for the suggested electrode mechanism. Generally, the complex is electrochemically reduced giving rise to two cyclic voltammetric waves. The first wave is a diffusion-controlled reversible wave. It is assigned to the stable Co(III)/Co(II) redox couple. The second one is found to be irreversible and corresponding to a reduction of Co(II) to Co(I) species. The monovalent cobalt, highly unstable, is rapidly protonated, and then forms cobalt hydride. The hydride decomposes to hydrogen molecules and regenerates Co(II) species following a disproportionation pathway. The overall reduction mechanism is concluded to be an EECC kinetics.     

流动注射分光光度法测定矿物浸提液中的游离氰化物

在氢氧化钠介质中游离的氰化物与苦味酸钠反应生成玫瑰红酸钠，并进行升温改善反应条件。双流路系统与单流路相比，峰形规范、光滑，能有效消除鬼峰，优化了显色条件，工作波长为５１０ｎｍ。按生产工艺要求的线性范围为４．０￣４０．０ｍｍｏｌ／Ｌ。进样频率为１３０次／ｈ。已成功地用于矿物浸提液中游离氰化物的现场分析。     

Adsorption study of an industrial dye by an organic clay

In this study, the adsorption of an industrial dye Supranol Yellow 4GL onto Cetyltrimethylammonium-bentonite (CTAB-bentonite) is investigated. The organobentonite is synthesised by exchanging cetyltrimethylammonium cations (CTAB) with inorganic ions on the surface of bentonite. The adsorption of Supranol Yellow 4GL onto organobentonite is found to be maximum when the concentration of CTAB exchanged is 100% according to the cation exchange capacity of the clay (CEC). The modification of organobentonite is examined using XRD and FTIR techniques. The effect of the process parameters such as: contact time, adsorbate concentration, adsorbent dose, pH and temperature are reported. Nearly 1200 seconds of contact time are found to be sufficient for the adsorption to reach equilibrium. The pseudo second order model is used to describe the kinetic data, and the rate constant is therefore evaluated. The dye adsorption to organobentonite is characterized by monolayer isotherm and caused by adsorption with relatively strong uptake. The Langmuir and Freundlich models adsorption are applied to describe the isotherm equilibrium and to determine its constants. The Langmuir and Freundlich models agree well with the experimental data with a adsorption capacity of 0.5 g of dye per g of organobentonite. A better fixation was obtained at acidic pH. The effect of temperature on the adsorption of dye has been also studied and the thermodynamic parameters ΔH, ΔS, ΔG, were determined. Organobentonite is found to be effective for removing Supranol Yellow 4GL dye from wastewater.     

电感耦合等离子体质谱法测定氧化钕中砷含量

建立草酸沉淀分离氧化钕,用校正方程消除残余钕离子产生的双电荷离子干扰,电感耦合等离子体质谱法测定砷含量的方法。选择了溶解样品条件,硝酸溶解样品即能满足检测要求;优化了仪器条件,功率1500W,雾化器流量0.86L/min;进行了内标元素的选择,确定Rh为最佳校正内标元素;确定用草酸分离基体并结合干扰校正方程消除钕的双电荷离子干扰;方法检出限为0.029 ng/mL,定量限为0.097 ng/mL。采用方法对实际样品进行测定,回收率(n=11)为94%～104%,相对标准偏差(RSD,n=11)为0.56%～5.82%。     

Soret and Dufour aspect of viscoelastic fluid due to moving cylinder with viscous dissipation and convective boundary conditions

Owing to contribution of thermo-diffusion phenomenon in various engineering and industrial frame works, scientists have presented some exclusive investigations on this topic. In current research, the thermos-diffusion prospective of second grade material accounted by a moving cylinder have been predicted. The applications of Soret and Dufour effects based on the thermos-diffusion phenomenon is evaluated. The magnetic force and viscous dissipation effects are presented for the current flow model. Additionally, the improvement in thermal transport of viscoelastic fluid is suggested with radiative phenomenon. The convective boundary constraints are used to report the thermos-diffusion phenomenon. The system based on dimensionless form is obtained with interaction of new variables. The shooting technique is used for numerical observations by using MATLAB software. The physical impact of phenomenon in view of parameters is graphically attributed. It has been noted that increasing velocity profile is results due to curvature parameter and viscoelastic parameter. The enhancement in thermal profile is noted due to Dufour number and Eckert number.