QuEChERS前处理液相串联质谱检测葡萄中35种农药残留

运用简便高效的QuEChERS前处理方法,液相-质谱联用测定葡萄中35种农药残留.结果:35种农药方法检出限为0.01～4.23 ng/g,加标回收率62.37％～118.56％,相对标准偏差1.01％～9.21％.标准曲线线性良好,相关系数0.9951～0.9999.此方法操作简便,试剂用量少,灵敏度和精密度高,适合用于葡萄中多种农药残留的高效率检测.     

三种检测方法对比水中莠去津残留研究

介绍三种方法检测水中莠去津残留,水样经过二氯甲烷液液萃取后,可分别采用液相色谱法、气相色谱法(NPD检测器、ECD检测器)三种方法进行检测,分别对比了三种色谱分析方法的实验条件和实验方法及如何制作标准曲线,并进行了精密度、回收率及检出限实验.结果表明,三种方法均可行,均适用于生活水和水源水中莠去津的检测.     

上海某原水泵站取水完善工程方案

针对上海某原水泵站需要在有限时间内需要通过改造,将输水能力由40万m3/d提升至62万m3/d的工程目标,研究现状输水泵房的主要瓶颈及优化方向,通过工艺、结构、造价等多专业的技术经济比较,提出以新建翻水泵房为核心的完善工程方案.方案具备实施工期短、功能保障度高的特点,同时,可永久解决原水库有效库容利用不足的问题,对同类原水泵站改造项目具备一定的借鉴参考意义.     

电网故障下光伏并网低压故障穿越控制策略的研究

电网发生故障或扰动可能造成光伏并网点电压跌落,严重影响电力系统的安全运行,光伏发电站有必要具备在电压跌落范围和时间内保证不脱网运行的能力。提出一种基于无功补偿的光伏并网低压穿越控制策略。该方法在检测到电压跌落时,通过断开外部电压环路将双闭环控制模式更改为单电流环路操作模式,采用改进后的无功补偿控制策略防止逆变器产生过电流,为电网电压提供无功补偿,较好实现不脱网运行。最后利用Matlab / Simulink软件比较和分析低压穿越控制策略前后的相关参数。仿真结果表明,改进的控制策略可以有效地抑制逆变器输出电流的增加,并且能提供无功功率来支持电网电压,以在电网电压骤降期间实现低压穿越。     

基于隐枚举法的快速分级切负荷优化方法

目前稳控装置广泛采用的穷举法已经很难满足快速、精准切负荷的要求。为了高效地求解切负荷优化问题,为紧急决策争取更多时间,提出了基于隐枚举法的快速分级切负荷优化方法。该方法协调低频和低压切负荷动作轮次,建立切负荷优化模型,通过制定合适的搜索策略和剪枝策略,仅在可行解范围内进行寻优,大大提高了计算最优解的效率。切负荷算例结果表明同等条件下该方法可以节约至少50%以上的计算时间,实现了稳控装置的快速切负荷,保证了紧急情况下电网的安全稳定运行。     

Thermoplastic polyurethane (TPU) modifier to develop bimodal cell structure in polypropylene/TPU microcellular foam in presence of supercritical CO2

Currently, the fabrication of microcell and bimodal cell structures (BCS) in polymer foams by using supercritical fluids has become a hot as well as a challenging research area worldwide. In this work, an environmentally friendly, effective, facile, and CO₂-based foaming technique was presented to fabricate microcellular polypropylene (PP) foams with BCS via blending with thermoplastic polyurethane (TPU). The toughness, thermal properties, rheological properties, and foamability of PP were systematically investigated with gradual incorporation of TPU. Representative sea-island structure was observed in the scanning electron microscopy (SEM) images for the fracture surface of various PP/TPU samples. Rheological measurement results demonstrated that the viscoelasticity of various PP/TPU samples was improved remarkably compared with that of pure PP and pure TPU. The impact strength of various PP/TPU samples possessed the highest value as 12.4 kJ/m² with the TPU content of 15 wt%. After the addition of TPU, an ameliorative cellular morphology was observed in the SEM micrographs of various PP/TPU samples and their volume expansion ratio was enhanced significantly thanks to their improved melt elasticity. Moreover, it is worth noting that BCS appeared in various PP/TPU foams when the TPU content exceeded 5 wt%.     

Synergistic effects of organically modified montmorillonite in combination with metal oxides on the fire safety enhancement of intumescent flame-retarded epoxy resins

Synergistic effects of organically modified montmorillonite (OMMT) in combination with different metal oxides (Bi₂O₃, Sb₂O₃, and MoO₃) on the fire safety enhancement of the intumescent flame-retarded epoxy resins (EPs) were systematically evaluated. The results from X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses show that the OMMT and metal oxides acquire a uniform distribution in the EP matrix, and OMMT platelets exhibit a fully exfoliated state. The flammability and thermogravimetry (TG) tests show that the intumescent flame retardant (IFR)-OMMT-metal oxide ternary system can endow EPs with the higher synergistic efficiencies on the enhancement of flame retardancy, smoke suppression properties, and charring ability compared to those of IFR or IFR-OMMT system, and the synergistic efficiency is the following order: IFR/OMMT/Sb₂O₃ > IFR/OMMT/MoO₃ > IFR/OMMT/Bi₂O₃. In particular, the sample, filled with 1.5 wt% OMMT, 1.5 wt% Sb₂O₃, and 27 wt% IFR, passes the UL94 V-0 rating and acquires the highest limiting oxygen index value of 28.5% among the samples. The IFR-OMMT-metal oxide ternary system exerts a better synergistic effect on the generation of crosslinking and aromatic structures that supply the excellent charring effect and barrier effect for the EPs, and the synergistic efficiency of IFR-OMMT-metal oxide ternary system is varied with the types of metal oxides.     

Boosting the Microbial Electrosynthesis of Acetate from CO2 by Hydrogen Evolution Catalysts of Pt Nanoparticles/rGO

Catalysis Letters - Microbial electrosynthesis (MES) is an effective approach to driving the CO2 reduction to multi-carbon organic products using renewable energy. In this work, the MES of acetate...     

PVP-assisted Sn-Ti microspheres for the efficient B–V oxidation of cyclohexanone

Journal of Porous Materials - New Sn-Ti microspheres were first successfully synthesized by a PVP-assisted sol-gel method in this paper, and their performance in the B–V oxidation of...     

Characterization of Urine Stem Cell-Derived Extracellular Vesicles Reveals B Cell Stimulating Cargo

Elucidation of the biological functions of extracellular vesicles (EVs) and their potential roles in physiological and pathological processes is an expanding field of research. In this study, we characterized USC–derived EVs and studied their capacity to modulate the human immune response in vitro. We found that the USC–derived EVs are a heterogeneous population, ranging in size from that of micro–vesicles (150 nm–1 μm) down to that of exosomes (60–150 nm). Regarding their immunomodulatory functions, we found that upon isolation, the EVs (60–150 nm) induced B cell proliferation and IgM antibody secretion. Analysis of the EV contents unexpectedly revealed the presence of BAFF, APRIL, IL–6, and CD40L, all known to play a central role in B cell stimulation, differentiation, and humoral immunity. In regard to their effect on T cell functions, they resembled the function of mesenchymal stem cell (MSC)–derived EVs previously described, suppressing T cell response to activation. The finding that USC–derived EVs transport a potent bioactive cargo opens the door to a novel therapeutic avenue for boosting B cell responses in immunodeficiency or cancer.