Fe3O4纳米粒子修饰多壁碳纳米管的制备及在水和蜂蜜样品中痕量菊酯类农药分析中的应用

通过化学共沉淀法使Fe₃O₄纳米粒子负载于酸化多壁碳纳米管(AMWNTs)表面,得到Fe₃O₄/AMWNTs磁性纳米材料。该材料具有很好的磁响应度和分散性,将其用于富集痕量拟除虫菊酯类农药残留,结果证明该复合材料对菊酯类农药的吸附性能良好。通过对影响萃取性能的几种因素如离子强度、萃取时间和解吸时间依次进行优化,在最优条件下,建立了Fe₃O₄/AMWNTs磁性分散固相萃取-气相色谱测定6种菊酯类农药残留的分析方法。线性范围在0.5~50 μg/L之间,相关系数(R²)大于0.990,检出限为0.07~0.20 μg/L,精密度为3.8%~8.1%。该方法用于河水、鱼塘水和两种市售蜂蜜中菊酯类农药的残留分析,回收率高于78.4%。该方法操作简便、灵敏度高,能够满足环境水样及蜂蜜样品中痕量菊酯农药残留的分析需求。     

基于多层叉指超微带电极阵列的葡萄糖传感器

采用多层工艺和光刻方法在玻璃衬底上加工了亚微米级金叉指型超微带电极阵列（IDA）,IDA电极的宽度为362nm,电极表面位于沟槽内。实验表明,所加工的IDA电极可作为生物和化学传感器的一次性超微基体电极。采用电聚合的方法将葡萄糖氧化酶（GOD）和吡咯（PPy）固定于IDA电极,该修饰电极可作为葡萄糖传感器。采用该葡萄糖传感器对磷酸钾缓冲溶液（pH7．0）中的葡萄糖浓度进行了比对测量,在2．0-7．0mmol／L的浓度范围内,传感器的响应时间为10s;灵敏度为14．6nA／（mmol／L）,相关系数为0．999。     

Metallo-phosphorylation of alkenes: a highly regioselective reaction of zirconocene-alkene complexes with chlorophosphate

Zirconocene-alkene complexes Cp₂Zr(CH₂CHR) reacted with chlorophosphate to form zircono-ethylphosphonate with high regioselectivity, which is versatile and could be converted into various functionalized organophosphonates.     

Clicking 1,2,4,5-tetrazine and cyclooctynes with tunable reaction rates

Substituted tetrazines have been found to undergo facile inverse electron demand Diels-Alder reactions with "tunable" reaction rates.     

奇妙缤纷“铬舞会”

Through the setting of anthropomorphic dance scene, the properties and applications of chromium and its compounds are introduced.     

Influence of Molecular Weight of Polysaccharides from Laminaria japonica to LJP-Based Hydrogels: Anti-Inflammatory Activity in the Wound Healing Process

In this study, polysaccharides from Laminaria japonica (LJP) were produced by the treatment of ultraviolet/hydrogen peroxide (UV/H₂O₂) degradation into different molecular weights. Then, the degraded LJP were used to prepare LJP/chitosan/PVA hydrogel wound dressings. As the molecular weight of LJP decreased from 315 kDa to 20 kDa, the swelling ratio of the LJP-based hydrogels rose from 14.38 ± 0.60 to 20.47 ± 0.42 folds of the original weight. However, the mechanical properties of LJP-based hydrogels slightly decreased. With the extension of the UV/H₂O₂ degradation time, the molecular weight of LJP gradually decreased, and the anti-inflammatory activities of LJP-based hydrogels gradually increased. LJP that were degraded for 60 min (60-gel) showed the best inhibition effects on proinflammatory cytokines, while the contents of TNF-α, IL-6, and IL-1β decreased by 57.33%, 44.80%, and 67.72%, respectively, compared with the Model group. The above results suggested that low Mw LJP-based hydrogels showed great potential for a wound dressing application.     

On matroids of the greatestW-connectivity

The Whitney connectivity (W-connectivity) of a matroidM is defined by T. Inukai and L. Weinberg as the least integerk for which there exists a subsetS of the ground setE ofM such that ?(S) ≥ k, ?(E ? S) ≥ k, andp(S)+p(E-S)-pM+1=k where ? is the rank function ofM.Mis called a Whitney matroid if there exists no such integer. In this case, theW-connectivity ofM to be the rank ofM is defined. In this paper, several properties of Whitney matroids are demonstrated. In addition, the Whitney matroids whose duals are also Whitney matroids are characterized, and an interpretation of binaryW-matroids is given.     

液相色谱-串联质谱法同时检测防晒化妆品中的11种紫外吸收剂

建立了防晒化妆品中11种紫外吸收剂的液相色谱-串联质谱检测方法。样品经甲醇-乙醇-水(80:10:10, v/v/v)提取,利用Eclipse XDB-C₁₈色谱柱(150 mm×4.6 mm, 5 μm)分离,以乙腈和0.1%甲酸水溶液为流动相,梯度洗脱。采用多反应监测(MRM)模式进行质谱测定,根据保留时间及质谱图上特征离子的相对丰度比进行定性,外标法定量。结果表明:该方法11种紫外吸收剂的定量限范围为200～500 mg/kg,回收率为77.17%～98.32%,相对标准偏差为2.40%～11.11%。该方法对于膏状和乳状防晒化妆品中的11种紫外吸收剂具有较好的适用性。