Capillary electrophoresis-acid barrage stacking online enrichment method for highly sensitive determination of four isoflavones

A capillary electrophoresis-acid barrage stacking online enrichment method has been established to detect the four isoflavones which are Daidzein, Genistein, Formononetin, and Biochanin A. The proposed method was optimized using a single factor alternative method, and the optimal conditions obtained from the optimization were: the BGE was 25 mM borax and 2 mM β-cyclodextrin, the applied separation voltage was 20 kV, and the detection wavelength was 260 nm. The time ratio of the injection of sample and the injection of acid was 150 s:20 s, and the acid used was 250 mM acetic acid. The sample solvent used was 60% v/v acetonitrile. The established method had the enrichment factor of these four isoflavones at 24.5, 32.0, 29.2, and 33.7, respectively, LOD and LOQ are as low as nanograms per milliliter. Finally, the CE-acid barrage stacking method was successfully applied to the determination of four isoflavones in rat plasma and red clover extract, verifying the applicability and feasibility of the method.     

A potential pentaerythritol-based bio-lubricants from 10-undecylenic acid: Its physico-chemical assessment

In this study, renewable, non-toxic, sulphur free bio-lubricants are synthesized as alternative for fossil fuels. We utilized a bio-derived 10-undecylenic acid (UDA) and pentaerythritol (PE) as raw materials to synthesize bio-lubricants by two-step chemical processes like esterification and followed by epoxidation reactions. And achieved a UDA-PE epoxide yielded 73.4%. The formation of UDA-PE ester and UDA-PE epoxide was confirmed by spectral analysis such as NMR (¹H and ¹³C), FTIR and mass spectra, Physico-chemical and basic lubricant properties by standard American Society for Testing and Materials methods (ASTM). The results showed that the products of UDA-PE ester and UDA-PE epoxide had high viscosity index (262 and 200), good pour points (−29 °C to −15 °C), high flash points (296 °C and 301 °C) respectively and these met the ISO VG (International Organization for Standardization-Viscosity grade) 22 and 220 standard values. In general, both synthesized products are plausible to be employed as bio-lubricant in industrial application.     

框架核酸高通量检测芯片

构建了一种基于框架核酸的高通量生物检测芯片.利用超微量移液自动化平台,将包含框架核酸探针的液滴按照预设命令固定至生物芯片微阵列上,在探针捕获核酸靶标后利用集成的基因芯片扫描仪对芯片进行成像,通过分析荧光强度定量化分析靶标浓度.结果表明,此框架核酸芯片能够实现框架核酸探针的高通量制备, 24 h即可制备具有15万个点的微阵列,且点间距离的相对偏差W≤10%、荧光强度的变异系数CV=3.30%,具有较高的稳定性,远高于国家标准.此外,该芯片具备高灵敏度、可寻址的高通量生物分析能力,对核酸靶标的检测限可达100 pmol/L.随着多种探针技术的发展,生物检测微阵列技术在高通量生物分析领域展示出巨大的潜力.     

CoFe2O4/CuO活化过氧乙酸高效降解磺胺甲恶唑(英文)

利用化学沉淀法和溶胶凝胶法,通过两步法成功制备出含有尖晶石钴铁氧体和氧化铜的复合催化剂CoFe₂O₄/CuO,通过扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和X射线衍射(XRD)对制备出的CoFe₂O₄/CuO进行表征,探究不同高级氧化体系对磺胺甲恶唑(SMX)去除能力,考察过氧乙酸(PAA)浓度、催化剂投加量、水体中常见干扰物质(Cl^-,HCO-3,SO₄^2-,HA)和不同自由基捕获剂对SMX去除的影响。分析结果表明CoFe₂O₄/CuO同时具有CoFe₂O₄与CuO的特征,对比单独CoFe₂O₄与CuO,CoFe₂O₄/CuO对PAA展现出极高的活化性能,在最佳反应条件下(催化剂投加量=20mg·L^-1,c(PAA)=200μ...     

Lewis酸催化纤维素制乳酸机理研究

Because fossil fuels are continuously depleted, valorization of biomass into valuable liquid products and chemicals is of great significance yet it remains challenging. Among many biomass-derived products, lactic acid is one of the most important renewable monomers for preparing the degradable polymer polylactic acid. The use of raw biomass to produce lactic acid through catalytic conversion is an attractive approach. In this work, the catalytic reaction performance and mechanism of different Lewis acids (Y³⁺, Sc³⁺, and Al³⁺) for the production of lactic acid from cellulose were investigated in detail by isotopic nuclear magnetic resonance (NMR) and mass spectrometry. The production of lactic acid from cellulose includes tandem and competing reactions. The order of catalytic activity for the one-pot conversion of cellulose into lactic acid is as follows: Y³⁺ > Al³⁺ > Sc³⁺. The main tandem reactions involve the hydrolysis of cellulose into glucose, the isomerization of glucose into fructose (the order of catalytic activity, the same below: Y³⁺ > Al³⁺, Y³⁺ > Sc³⁺), the cleavage of fructose via a retro-aldol reaction to glyceraldehyde (GLY) and 1, 3-dihydroxyacetone (DHA) (Sc³⁺ > Y³⁺ > Al³⁺), and the conversion of DHA or GLY to the final product lactic acid (Al³⁺ > Y³⁺ > Sc³⁺). It was found that the process of glucose isomerization to fructose was the key step to the final selectivity of the tandem reaction of cellulose conversion to lactic acid, and it was clarified that the production of lactic acid from DHA underwent a keto-enol (K-E) tautomerization process rather than a classical 1, 2-shift process. First, DHA was transformed into GLY via the isomerization process, then the adjacent hydroxyl group of GLY was removed in the form of water to produce an α, β-unsaturated species. After that, the α, β-unsaturated species underwent K-E tautomerization to generate unsaturated aldehyde-ketone intermediates. Meanwhile, a molecule of water was added to aldehyde-ketone intermediates to obtain a diol product, the hydrogen atom at the methine position was transferred and the lactic acid was finally obtained through the K-E tautomerization process. The in-depth understanding of the reaction mechanism presented in this work will help to design more selective catalysts for cellulose conversion into value-added oxygen-containing small molecule chemicals.      

Preparation and application of novel polymer nanoparticles in the detection of copper ion and cysteineEI北大核心CSCD

A novel amphiphilic copolymer,dipropenoxystyrene anthracene and acrylic acid copolymer（BASA-AA） was designed and synthesized based on divinyl anthracene. The polymer self-assembled rapidly in water to create polymer nanoparticles（BASA-AA NPs）with a uniform size of 45 nm,no dye leakage,and great brightness（Φ= 36%）. Because of the enormous number of carboxyl groups on the surface of the particles,it can disperse extremely well in water,and can be used for the rapid detection of copper ion and cysteine（Cys）in pure water, with the limit of detection of 45 nmol/L. The fluorescent intensity of the nanoparticles will be greatly reduced after the introduction of copper ion,realizing the detection of copper ion with high selectivity and sensitivity. A composite probe made of BASA-AA NPs and copper ion can detect Cys in the range of 0.1-10 µμmol/L,with the detection limit of 84 nmol/L,due to the high binding capacity of the sulfhydryl group and copper ion. The method is simple and rapid in material synthesis and preparation,and shows high selectivity and sensitivity in pure water. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Determination of lanthanum and cerium in cmsx-4 nickel-based superalloys by inductively coupled plasma mass spectrometryEI北大核心CSCD

CMSX-4 is the second-generation nickel-based single crystal superalloy used widely in the world. The oxidation resistance and corrosion resistance of CMSX-4 alloy can be improved by adding trace lanthanum (La), cerium (Ce) and other rare earth elements. A method for the simultaneous determination of La and Ce in CMSX-4 nickel-based superalloy by wet dissolution-inductively coupled plasma mass spectrometry was established. The sample was heated and dissolved under normal pressure by aqua regia and hydrofluoric acid, and the interference of fluorine ion was eliminated by using perchloric acid. The amount of dissolved acid and the digestion conditions were optimized. The limits of detection were 0.23 μg/g for La and 0.85 μg/g for Ce under optimized conditions. The spiked recoveries were 95.0%–98.9% with the relative standard deviations of 1.3%–3.9%, which can meet the requirements of accurate and rapid determination of La and Ce in CMSX-4 nickel-based superalloy. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

氮掺杂石墨烯负载单原子Zr催化CO2加氢的密度泛函理论研究

基于密度泛函理论计算,研究了H2和CO2在氮掺杂石墨烯负载单原子Zr催化剂(Zr Nx-Gr)上的吸附和CO2催化加氢反应. H2和CO2在Zr N3-Gr上单独吸附的吸附能分别为-0.49和-2.17 e V,在H2和CO2共吸附状态下,吸附能为-2.24 e V,均高于在Zr N4-Gr表面的吸附能,表明Zr N3-Gr表面更利于CO2加氢反应的发生.在Zr N3-Gr表面, CO2在共吸附后保持了其单独吸附时的特性,削弱了H2分子的吸附. CO2在Zr Nx-Gr表面催化加氢反应起始于H2和CO2的共吸附构型,沿反式HCOOH路径形成甲酸盐(HCOO*)中间体,然后HCOO*基团吸附H原子形成反式甲酸,在Zr N3-Gr和Zr N4-Gr表面该路径的反应能垒分别为1.85和2.48 e V.另一路径为产生CO与H2O的反应,在Zr N3-Gr和Zr N4-Gr表面的反应能垒分别为1.86和1.73 e V,表明Zr N3-Gr更利于CO2加氢生成甲酸反应的发生,而Zr N4-Gr表面更利于CO的产生.     

活性导向的化学探针在氨基酸反应活性表征中的应用进展

原创药物的研制得益于蛋白质新靶标的发现,而新靶标的发现依赖于高可信度、高通量的药物-蛋白质相互作用分析方法。蛋白质作为生命功能的执行者,其表达量、空间定位与结构差异直接影响药效的发挥。目前,超过85%的蛋白质尚被认为是无法成药的,主要原因是缺少药物分子靶向的空腔以及相应的反应活性位点。因此,基于蛋白质组学层次实现对氨基酸反应活性位点的表征成为原创共价靶向药物设计的关键,也是克服难以成药靶标蛋白问题的关键。近年来,质谱技术的飞速发展极大地推动了基于蛋白质组学技术的药物-靶蛋白相互作用研究。其中基于活性的蛋白质组分析(ABPP)策略是利用活性位点导向的化学探针分子在复杂样品中实现功能状态酶和药物靶标等蛋白质的检测。基于化学探针的开发和质谱定量技术的发展,ABPP技术在氨基酸反应活性表征研究中展现出重要的应用潜力,将助力于药物新靶标的发现和药物先导化合物的开发。ABPP策略主要基于蛋白质的活性特征进行富集,活性探针作为ABPP策略的核心,近年来取得了飞速进展。该文回顾了ABPP策略的发展历程,重点介绍基于广谱活性探针的ABPP技术在多种氨基酸反应活性筛选领域的研究进展,并对其在药物靶点发现中...     

脱氢枞酸酯键合硅胶色谱固定相的制备及应用

将天然可再生资源脱氢枞酸与甲基丙烯酸缩水甘油酯反应制得脱氢枞酸酯（DAGME）,并将其通过“巯-烯”点击反应接枝到巯基功能化硅胶表面,制备得到一种疏水型脱氢枞酸酯键合硅胶色谱固定相（SilDAGME）。利用傅里叶变换红外光谱（FT-IR）、热失重分析（TGA）和元素分析（EA）对固定相进行表征,结果表明Sil-DAGME固定相成功制备。以烷基苯、Tanaka测试混合物、多环芳烃、酚类化合物和黄酮类化合物作为分离对象对Sil-DAGME的分离性能及保留机制进行评价。研究发现Sil-DAGME除疏水作用保留机制外,还具有氢键和π-π相互作用。基于多种保留机制的协同作用,Sil-DAGME对上述分析物均表现出良好的分离性能。此外,Sil-DAGME不仅具有良好的重现性（RSD为0.050%～0.19%,n=10）、稳定性（RSD为0.25%～1.0%,n=7）和可重复制备性（RSD为0.78%～2.1%,n=3）,还对红豆杉树皮粗提物表现出良好的分离效果。将脱氢枞酸用于制备新型的色谱填料不仅为紫杉醇的分离和检测提供了一种新途径,也为以天然产物松香作为功能配体设计和制备新型固定相提供了参考。