Analysis of 21 progestagens in various matrices by ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) with diverse sample pretreatment

In this study, a highly sensitive and robust method using an ultra-high-performance liquid chromatography-tandem mass spectrometry combined with solid-phase extraction and ultrasonic extraction for pretreatment and silica gel purification steps has been developed for determination of 21 natural and synthetic progestagens in river surface water and sediments, and influents, effluents, and sludge from municipal wastewater treatment plants, and flush water and feces from swine farms. For the various matrices considered, the optimized method showed satisfactory performance with recoveries of 70–129 % (except AD, 5α-DHP, DPT, HPC), the limits of quantification below 2.30 ng/L for liquid samples and 2.59 ng/g for solid samples (except AD), and good linearity and reproducibility. This developed method was successfully applied in the analysis of progestagens in environmental samples from Liuxi Reservoir, Xintang municipal wastewater treatment plant, and Shunfeng swine farm in South China. Six analytes were detected at trace levels in surface water, effluent, and sediment samples. Seven analytes (0.7 (HPA)–35.1 ng/L (DGT)) were found in the influent samples and three analytes (5.6 (DGT)–11.8 ng/g (5α-DHP)) in the dewatered sludge samples. Moreover, 13 analytes were detected in swine farm, with high concentrations ranging from 23.8 ng/L (ET) to 5,024 ng/L (P) in flush water, and from 20.0 ng/g (MPA) to 1952 ng/g (P) in feces.     

新课程背景下高中生化学学习障碍调查及成因分析

为了解高中生化学学习障碍程度,采用问卷调查的方式在湖北省武汉市2所省重点中学展开调查,从“教材原因”“教师原因(教学策略、评价策略)”“实验原因”3个层面对现阶段高中生化学学习障碍成因进行初步分析,并从教学策略、评价策略、实验策略等方面提出相关教学建议.     

双波长二极管合束端面抽运掺镨氟化钇锂单纵模360nm紫外激光器

报道了一种双波长半导体激光二极管(LD)合束端面抽运掺镨氟化钇锂晶体(Pr~(3+):LiYF_4)全固态、单纵模360nm紫外激光器.该激光器采用V形折叠腔结构,利用反射式体布拉格光栅作为波长选择反射镜来压缩光谱线宽,与法布里-珀罗(F-P)标准具组合构成窄带滤波器进行单纵模的有效选取,通过Ⅰ类位相匹配切割的倍频晶体三硼酸锂对腔内720nm基频光进行倍频.在444nmLD输出功率为1200mW和469nmLD输出功率为1400mW时,合束抽运获得了功率为112mW的连续单纵模360nm紫外激光稳定输出,光-光转换效率为4.3%.测量结果表明,边摸抑制比大于60dB,4h功率均方根值稳定性优于0.5%,1h频率漂移小于220MHz,激光振幅噪声小于0.5%.     

Emerging weak antilocalization effect in Ta0.7Nb0.3Sb2 semimetal single crystals

Weak antilocalization (WAL) effect is commonly observed in low-dimensional systems, three-dimensional (3D) topological insulators and semimetals. Here, we report the growth of high-quality Ta_0.7Nb_0.3Sb₂ single crystals via the chemical vapor transport (CVT). Clear sign of the WAL effect is observed below 50 K, probably due to the strong spin−orbital coupling in 3D bulk. In addition, it is worth noting that a relatively large MR of 120% appears under 1 T magnetic field at T = 2 K. Hall measurements and two-band model fitting results reveal high carrier mobility (>1000 cm²·V⁻¹·s⁻¹ in 2–300 K region), and off-compensation electron/hole ratio of ~8:1. Due to the angular dependence of the WAL effect and the fermiology of the Ta_0.7Nb_0.3Sb₂ crystals, interesting magnetic-field-induced changes of the symmetry of the anisotropic magnetoresistance (MR) from two-fold (≤ 0.6 T) to four-fold (0.8–1.5 T) and finally to two-fold (≥ 2 T) are observed. This phenomenon is attributed to the mechanism shift from the low-field WAL dominated MR to WAL and fermiology co-dominated MR and finally to high-field fermiology dominated MR. All these signs indicate that Ta_0.7Nb_0.3Sb₂ may be a topological semimetal candidate, and these magnetotransport properties may attract more theoretical and experimental exploration of the (Ta,Nb)Sb₂ family.     

局部塑性变形下铁基金属玻璃的致密化和非均匀性增强

本文研究了经局部塑性变形后, Fe₇₈Si₉B₁₃金属玻璃在原子尺度上的结构演变及其对合金显微硬度的影响.借助砂纸作为传力的媒介,充分放大了作用于带材表面上的等效压力,发生塑性变形后合金表面产生了大量的剪切带.基于倒空间和实空间的同步辐射X射线衍射分析,在塑性变形后,合金结构的致密度增大,过剩自由体积被排出,并由此揭示了Fe₇₈Si₉B₁₃金属玻璃在短程及中程尺度上原子协同重排行为.结合高分辨透射电子显微镜观察的结果, Fe₇₈Si₉B₁₃金属玻璃在发生塑性变形后,结构不均匀的程度将会加剧.此外,不同于单轴加载下金属玻璃的加工软化, Fe₇₈Si₉B₁₃金属玻璃在发生局部塑性变形后,维氏硬度增大,表现出局部的加工硬化行为.从自由体积的角度看,合金表面的大量剪切带可能是由于剪切带影响区域的重叠和交叉发生相互作用,并加速原子迁移,...     

Functionalization of carbon nanotubes/graphene by polyoxometalates and their enhanced photo-electrical catalysis

Carbon nanotubes and graphene are carbon-based materials, which possess not only unique structure but also properties such as high surface area, extraordinary mechanical properties, high electronic conductivity, and chemical stability.Thus, they have been regarded as an important material, especially for exploring a variety of complex catalysts. Considerable efforts have been made to functionalize and fabricate carbon-based composites with metal nanoparticles. In this review,we summarize the recent progress of our research on the decoration of carbon nanotubes/graphene with metal nanoparticles by using polyoxometalates as key agents, and their enhanced photo-electrical catalytic activities in various catalytic reactions. The polyoxometalates play a key role in constructing the nanohybrids and contributing to their photo-electrical catalytic properties.     

基于发卡式开口谐振环的柔性双频带超材料

本文设计了一种基于开口谐振环(split ring resonator, SRR)混合排列单元格的小型化双频带超材料(metamaterial, MM). 该MM的单元结构为发卡式SRR, 所设计的双频带MM可以应用于无线局域网(2.4 GHz) 和全球微波互联接入(3.5GHz)系统. 并且, 采用柔性介质作为基板增加了MM的柔韧度和普适性, 实验和测试结果表明: 双频带MM的中心频率可以通过调节SRR的尺寸进行控制. 此外, 本文也对MM在不同入射角的情况进行了分析, 结果表明MM对入射角度不敏感.最后, 通过MM的表面电流分布情况研究, 进一步解释了其双频带谐振频率的产生原理.     

磁性UiO-66复合材料的合成及其对水体中硝基酚有机分子的吸附性能

以溶剂热法制备了Fe₃O₄@SiO₂-PSS@UiO-66结构的磁性多孔复合材料,并利用XRD,TEM,SEM,IR,TG,VSM 和N₂吸附-脱附对样品的结构和形貌进行测试表征。研究结果表明：磁性UiO-66复合材料是以球型Fe₃O₄为核,MOF为壳的核-壳结构,其表面的MOF层由多个立方多晶堆积组装而成,且具有良好的超顺磁性。进一步研究了Fe₃O₄@SiO₂-PSS@UiO-66对2-硝基-1,3-苯二酚的吸附性能。探讨了吸附时间,吸附量和2-硝基-1,3-苯二酚初始浓度在吸附过程中的影响,结果表明：当吸附时间为12 h,吸附剂的用量为5 mg,2-硝基-1,3-苯二酚浓度为400 mg·L^-1时,最大吸附量为161.36 mg·g^-1。另外,磁性UiO-66复合材料对2-硝基-1,3-苯二酚高的吸附性能可能是由于UiO-66与2-硝基-1,3-苯二酚之间的静电作用以及二者之间苯环的π-π作用。     

Effects of concave and convex substrate curvature on cell mechanics and the cytoskeleton

In order to understand how cells respond to concave and convex subcellular surface structures,colloidal crystal array and honeycomb-structured surfaces composed of highly ordered hexagonal units with completely inverse curvature were fabricated via facile self-assembly and breath figure approaches, respectively.The influence of hexagonal surface curvature on cell fate was subsequently investigated. Cells underwent more extensive spreading on the convex colloidal crystal array surface,while adhesive forces were higher on the concave honeycomb surface.The behaviors of cells on the different surfaces were investigated by comparing cell morphology,cellular adhesive force and cytoskeleton structure.The results revealed comprehensive differences in cell behavior between those on concave honeycomb surfaces and convex colloidal crystal arrays.     

声化学辅助溶剂热合成高光催化性能的BiOCl光催化剂

以五水硝酸铋和氯化钠为原料,乙二醇(EG)和水作溶剂,通过声化学辅助溶剂热法合成了系列BiOCl纳米晶光催化剂。应用氮气物理吸附、X射线粉末衍射(XRD)、扫描电镜(SEM)、傅里叶变换红外光谱(FTIR)、紫外-可见(UV-Vis)漫反射(DRS)和光电流等测试手段对所制备的光催化剂进行了表征。在汞灯和氙灯照射下,以苯酚和甲基橙为水体模型污染物,系统考察了超声辐射时间和醇水比(VEG/VH2O)对BiOCl光催化剂性能的影响。结果表明,当超声辐射时间为60 min,VEG/VH2O=1/4时,合成的BiOCl表现出最佳的光催化活性,为常规沉淀法制备的BiOCl的3.3倍。活性提高的主要原因是,适当时间的超声波辐射和醇水比有利于催化剂比表面积的提高,同时可以丰富催化剂表面羟基(-OH)的数量和提高光生电子和空穴的分离效率。