气相色谱-负化学离子源质谱测定大豆和玉米中12种三唑类杀菌剂的残留量

建立了一种可用于大豆和玉米中12种三唑类杀菌剂残留量测定的分散固相萃取-气相色谱-负化学离子源质谱方法。样品经含1%冰醋酸的乙腈提取,分散固相萃取法净化,采用气相色谱-负化学离子源质谱分时段选择离子监测技术进行测定与确证,外标法定量。12种农药在50～1000 μg/L范围内线性关系均良好;所有农药的方法定量限(LOQ)均低于8 μg/kg;在10,20和40 μg/kg 3个添加水平下所有农药的回收率为70%～130%,相对标准偏差(RSD)≤13.9%。该方法在检测大豆和玉米基质时无干扰现象出现。     

Sr2MoBO6(B=Os、Re、W)的电子结构与光学性质的第一性原理

双钙钛矿氧化物Sr2 MoBO6(B=Os、Re、W)已被预测为具有高磁转变温度的半金属材料.本论文对Sr2 MoBO6的电子结构和光学性质进行了第一性原理计算,并分析了二者之间的内在关系.从能带结构来看,Sr2 MoOsO6和Sr2 MoWO6为半金属,Sr2 MoReO6为普通金属.B 5d与Mo 4d之间的跃迁过...     

水介质对有机硫化物形成影响的模拟实验

利用高压釜反应装置在高温高压下开展了汽油-硫酸镁化学还原反应含水和无水体系的模拟实验,通过气相色谱仪、微库仑仪、毛细管气相色谱/脉冲火焰光度检测器、红外光谱仪及X射线衍射仪对气、油、固三相产物分别进行了分析并对动力学进行了解析,表明主要生成氧化镁、硫、焦炭、硫化氢、二氧化碳以及硫醇、硫醚和噻吩类等有机硫化物;随反应温度升高,反应体系中无机硫转化为有机硫的趋势增强,并主要生成热稳定性高的噻吩硫。 动力学解析表明,含水和无水条件硫酸镁转化反应的活化能分别为68.9和78.5 kJ/mol,证明水存在有利于无机硫向有机硫转化。     

Residual Based a Posteriori Error Estimates for Convex Optimal Control Problems Governed by Stokes-Darcy Equations

In this paper, we derive a posteriori error estimates for finite element approximations of the optimal control problems governed by the Stokes-Darcy system. We obtain a posteriori error estimators for both the state and the control based on the residual of the finite element approximation. It is proved that the a posteriori error estimate provided in this paper is both reliable and efficient.     

管线上卷极限弯矩分析

利用弹塑性理论对卷管施加弯矩载荷时的截面屈服过程进行了理论分析,得出了卷管上卷时卷管所能承受的极限弯矩;通过实例分析得出X65钢在发生塑性应变为2.5%时的卷管两端截面夹角为1.98rad、滚筒直径为5.05m、极限弯矩为99.2kN m。根据DNV-OS-F101和API-RP-1111的相关规定,可将99.2kN m界定为对卷管施加弯矩的上限值;卷管弯矩上限值对应卷管上卷时的滚筒直径上限值,表明卷管上卷时可通过滚筒直径来限制卷管弯矩值。本文结果可为深水管线卷轴铺设的应用提供理论依据。     

Experimental investigation on the distribution uniformity and pressure drop of perforated plate distributors for the innovative spray-type packed bed thermal storage

As an innovative thermal energy technology,the spray-type packed bed has advantages of high efficiency and low cost.A liquid distributor is the key component fo...     

Combined biocompatible medium with molecularly imprinted polymers for determination of aflatoxins B1 in real sample

A kind of molecularly imprinted polymers modified with biocompatible medium was prepared by suspension polymerization. The obtained hybrid materials were used as the adsorbents for the solid‐phase extraction of aflatoxins B1 in real samples. A structural analog of the target, 6‐methyl‐4‐phenylchroman‐2‐one was used as the pseudo‐template, owing to their lower toxicity and cheaper price compared with aflatoxins B1; and methacrylic acid and glycidyl methacrylate were used as the co‐monomers. Scanning electron microscopy and size distribution analysis were used to characterize the obtained polymers. The extraction parameters were optimized to achieve the desired extraction performance. The polymer solid‐phase extraction coupled with high‐performance liquid chromatography was successfully applied to determine aflatoxins B1 from soy sauce without the process of protein removal. Under the optimum extraction conditions, the detection results of aflatoxins B1 in lab‐made column in soy sauce samples was carried out, with a recovery rate of 96%. The established method presented a linear range from 10 to 1000 ng/mL with the coefficient of determination of 0.9994 and the limit of detection of 0.05 ng/mL. Likewise, the inherent selectivity of lab‐made column towards aflatoxins B1, Ochratoxin A, and Zearalenone was demonstrated.     

Fabrication of nanoporous polymeric crystalline TiO2 composite for photocatalytic degradation of aqueous organic pollutants under visible light irradiation

A nanoporous polymeric crystalline TiO₂ composite (TiO₂/PDVB‐MA) has been successfully synthesized through an in situ synthesis method using divinylbenzene (DVB), methacrylic acid (MA) and tetrabutyl titanate. The experimental results showed that TiO₂ nanoparticles composed of the mixture phases of anatase and rutile were homogeneously dispersed into the PDVB‐MA support. The TiO₂/PDVB‐MA composite was used as photocatalyst for Rhodamine B (RhB), bisphenol A and 2,4,6‐trichlorophenol degradation under visible light irradiation. More interestingly, the excellent photocatalytic performance of the composite was observed with regard to RhB and bisphenol A, which might be ascribed to the synergistic effect between TiO₂ nanoparticles and PDVB‐MA. Moreover, TiO₂/PDVB‐MA composite could be recycled at least four times in the removal of RhB, suggesting that it is a promising photocatalyst to catalyze the degradation of organic pollutants under visible light irradiation.     

An electrochemical aptasensor based on bifunctional Fe3O4@Au nanocomposites for adenosine triphosphate assay

Journal of Solid State Electrochemistry - We describe a label-free electrochemical aptasensor for adenosine triphosphate (ATP) assay based on bifunctional Fe3O4@Au nanocomposites. Due to the...     

Porous Magnetic Nanoparticles-Based Electrochemical Biosensor for Determination of Mercury in the Aquatic Environment

Fabrication of sensitive and convenient methods for the detection of heavy metal ions is an important task due to their high toxicity to environment and human health. Divalent mercury ions (Hg²⁺) are a kind of significant public health hazard, which generate harmful toxic effects. In this work, a novel self-powered biosensor for the quantification of Hg²⁺ in aqueous solutions is developed. Porous magnetic nanoparticles are synthesized to load electrochemical species and a Hg²⁺ responsive single-stranded DNA probe is used to seal them. After specific interaction with target ions, the DNA probe forms a rigid duplex, which can no longer block the pores of the magnetic nanoparticles. The leakage of electrochemical species can then increase the electrochemical response, which is used to indicate the initial concentration of Hg²⁺. This method shows high sensitivity and selectivity, and can be applied in real water samples with excellent recoveries. Therefore, a novel approach is provided for ultrasensitive and reliable detection of Hg²⁺ in practical applications.