Total Synthesis of Camptothecin and Related Natural Products by a Flexible Strategy

A flexible strategy for constructing natural products containing indolizinone or quinolizinone scaffolds and their analogues was developed, which was based on a cascade exo hydroamination followed by spontaneous lactamization. This method was applied in the total synthesis of camptothecin in nine steps in a new ring‐forming approach. It was also used to efficiently prepare five biogenetically or structurally related natural alkaloids, including 22‐hydroxyacuminatine, oxypalmatine, norketoyobyrine, naucleficine, and nauclefine, as well as 35 natural‐product‐like molecules. We believe that this method and the small‐molecule library prepared with it can open new avenues for studying the bioactivity of camptothecin and Nauclea natural products.     

Electrochemical properties of high-power supercapacitors using ordered NiO coated Si nanowire array electrodes

Highly ordered NiO coated Si nanowire arrays are fabricated as electrode materials for electrochemical supercapacitors (ES) via depositing Ni on electroless-etched Si nanowires and subsequently annealing. The electrochemical tests reveal that the constructed electrode has superior electrical conductibility and more active sites per unit area for chemical reaction processes, thereby possessing good cycle stability, high specific capacity, and low internal resistance. The specific capacity is up to 787.5 F g⁻¹ at a discharge current of 2.5 mA and decreases slightly with 4.039% loss after 500 cycles, while the equivalent internal resistance is ∼3.067 Ω. Owing to its favorable electrochemical performance, this ordered hybrid array nanostructure is a promising electrode material in future commercial ES.     

生物降解型聚氨酯材料的研究：Ⅰ.控制释放化肥包覆材料

以树皮为原料，合成了生物降解型聚氨酯泡沫材料，并考察了其作为化肥缓释的包膜材料对常用氮肥硫酸铵的控制释放性能。研究结果表明，以水作为发泡剂的多孔性聚氨酯包裹硫铵后，在模拟自然界雨淋的作用下，释放曲线大致呈抛物线型。释放的速度与所包裹的硫铵量关系不大；发泡时水的比例越高，释放速度越快；颗粒越大，释放越慢；树皮的比例越高，释放越慢。对包膜材料的生物降解性方面的初步实验结果表明：该材料在土壤中能够自然降     

石墨炉原子吸收法测定玉米中镉

本文研究了石墨炉原子吸收法测定玉米中镉的方法。用聚四氟乙烯高压消化弹溶解样品，用金属钯做基体改进剂和李沃夫平台石墨管提高方法的灵敏度。用本法测定镉的检出限为０．１２ｐｐｂ，相对标准偏差为２．６６％（ｎ＝１１），方法的回收率为９７％－１０５％之间。     

应用单宁与淀粉为交联剂改性聚氨酯

通过植物原料单宁与淀粉对聚氨酯的改性可提高聚氨酯的机械性能和热性能 ,单宁成分的导入还能有效提高聚氨酯交联点密度、组分相容性和体系的形态结构均匀性 .当单宁的含量占投入的植物原料的6 0wt%时 ,单宁和淀粉聚氨酯网络互相贯穿表现出良好的相容性 ,其拉伸强度、杨氏模量分别提高到 5 1 9MPa和 30 8 4MPa ,积分程序分解温度达到 375℃ .同时单宁成分有望在一定范围内调节聚氨酯的降解速度 .     

液相色谱-串联质谱同时测定家禽组织中16种磺胺残留

5g家禽组织样品,用乙腈提取,旋转蒸发器减压蒸干后,用乙腈0．01mol／L乙酸铵溶液溶解（12：88,V/V）,用正己烷去除脂肪后,样液用高效液相色谱分离,电喷雾串联四级杆质谱进行检测,外标法定量。本方法研究的16种磺胺（磺胺甲噻二唑、磺胺醋酰、磺胺嘧啶、磺胺氯哒嗪、磺胺甲基异唔唑、磺胺甲基嘧啶、磺胺吡啶、磺胺二甲异嘌唑、磺胺-6-甲氧嘧啶、磺胺邻二甲氧嘧啶、磺胺甲氧哒嗪、磺胺间二甲氧嘧啶、磺胺噻唑、磺胺二甲嘧啶、磺胺甲氧嘧啶、磺胺苯吡唑）的线性范围为0．2—120ng,线性相关系数r〉0．995;在2．5—600μg/kg的4个添加水平范围内的平均回收率为75．4％-97．3％;相对标准偏差为3．48％-14．09％;方法检出限（LOD）为1．0—12．0μg／kg;方法定量限（LOQ）为2．0—24．0μg/kg。     

液相色谱-串联质谱法快速测定蜂蜜中3种硝基咪唑类药物残留

建立了液相色谱-串联质谱(LC-MS/MS)快速测定蜂蜜中甲硝唑、洛硝哒唑和二甲硝咪唑3种硝基咪唑类药物残留的分析方法。蜂蜜样品用水溶解后,直接上样至Oasis HLB固相萃取柱净化,依次用水和甲醇-水溶液(1:9, v/v)淋洗,用乙酸乙酯洗脱。洗脱液经浓缩、溶解、过滤后进行LC-MS/MS检测,外标法定量。在添加水平为0.05～2.0 μg/kg时,平均添加回收率为76.6%～89.7%,相对标准偏差(n=8)为5.2%～9.9%。甲硝唑的检出限为0.1 μg/kg,洛硝哒唑、二甲硝咪唑的检出限均为0.2 μg/kg。应用所建立的方法对出口蜂蜜样品进行了测定,结果表明该方法操作简单、快速,结果准确、可靠,灵敏度和准确度满足现在日本和欧盟对蜂蜜中3种硝基咪唑类药物残留量的检测要求。     

单宁聚氨酯土壤微生物降解研究

采用凝胶渗透色谱仪(GPC)、傅立叶变换红外光谱仪(FT-IR)和电子扫描显微镜(SEM)等实验手段,考察了单宁聚氨酯(WT-PU)在土壤微生物降解前后的化学结构与微观形态的变化,而作为比较用的模型化合物(TMP-PU)在同样的条件下几乎没有变化。结果表明单宁一这交联点在PU整体中以无规降解的方式优先降解,在整个降解过程中,不仅伴随着PU硬段的氢键减弱,软段的氢键也同样有相当的减弱。     

Isolation and purification of high polar glycosides from aerial parts of Gynostemma pentaphyllum (Thunb.) Makino by linear gradient counter-current chromatography coupled with inner-recycling mode

Gynostemma pentaphyllum (Thunb.) Makino represents the popular health food and supplemental product with broad pharmacological activities. The highly polar glycosides, including flavonoids and saponins, are major effective active components that contain diverse sugar positions and quantities, which result in diverse chemical polarities, making it challenging to separate and isolate these components. The present work described the rapid and efficient linear gradient counter-current chromatography to preparatively separate glycosides from aboveground parts of G. pentaphyllum. Besides, the ethyl acetate and n-butanol binary mobile phases were achieved through adjusting associated proportions. Six glycosides, including quercetin-3-O-neohesperidoside ( 1 ), kaempferol-3-O-robinobioside ( 2 ), kaempferol-3-O-neohesperidoside ( 3 ), gypenoside LVI ( 4 ), ginsenoside Rb3 ( 5 ), and gypenoside XLVI ( 6 ), were isolated at the purities greater than 98%. Moreover, electrospray ionization mass spectrometry and nuclear magnetic resonance tandem mass spectrometry were conducted for structural identification. According to our findings, the established linear gradient counter-current chromatography was an efficient approach to separate the highly polar glycosides from aboveground parts of G. pentaphyllum. Our proposed strategy can be used to separate active compounds from other complex natural products.