Preparation and Porous Property of C14-Monolithic Column for Capillary Electrochromatography

Capillary electrochromatography (CEC) has been performed with a series of C₁₄, methlyacrylamide based monolithic columns. These monoliths with different porosities were prepared by in-situ copolymerization in fused-silica capillaries. The porous properties of monoliths were further observed using scanning electron micrographs (SEM) and measured using a mercury porosimeter. The effect of various alcohols as porogens on porous structural properties and chromatographic behaviors were also investigated. The effects of organic additive, pH value and ionic strength in mobile phase on electroosmosis flow (EOF) and separation were further discussed. Meanwhile, the baseline separation of 6 neutral compounds can be well obtained. In addition, the monolithic column demonstrates the high column efficiency and satisfactory reproducibility.Acknowledgements We gratefully acknowledge the support of the National Natural Science Foundation of China.     

Study of a fluorescence quenching mechanism of enoxacin and its determination in human serum and urine samples

The maximum emission wavelength of dopamine is 317 nm with excitation at 290 nm. The relative fluorescence intensity of dopamine decreased in the presence of enoxacin, which showed that fluorescence quenching occurred. The Stern-Volmer (S-V) plot showed a nonlinear relationship between the relative fluorescence intensity of dopamine and the concentration of enoxain. The quenching mechanism was studied and the results suggested that both dynamic and static quenching processes were responsible for the observed positive deviation in the S-V plot. When the S-V plot was modified by logarithm, the linear relationship was obtained between logF ₀/F and C in the range of 0.10 to 13.0 μg/mL (where F ₀ is the relative fluorescence intensity of dopamine, F is the relative fluorescence intensity of dopamine in the presence of enoxacin, and C is the concentration of enoxacin). The fluorescence quenching method for the determination of enoxacin was developed. The linear regression equation of the calibration graph of enoxacin was C = 13.70 (logF ₀/F) − 0.5836, with the correlation coefficient 0.9984. The detection limit was 2.0 ng/mL and the relative standard deviation was 2.52%. The effects of pH, the stability of dopamine in the presence of enoxacin, and foreign ions on the determination of enoxacin have been examined. The recovery of enoxacin was from 94.9 to 103.0% in a human serum sample and from 94.9 to 108.0% in a urine sample. The method is simple, rapid, and can be used for the determination of enoxacin in human serum and urine samples with satisfactory results. The text was submitted by the authors in English.     

Study on electrochemical behavior of tryptophan at a glassy carbon electrode modified with multi-walled carbon nanotubes embedded cerium hexacyanoferrate

Electrochemical behavior of cerium hexacyanoferrate (CeHCF) incorporated on multi-walled carbon nanotubes (MWNTs) modified GC electrode is investigated by scanning electron microscopy (SEM) and electrochemical techniques. The CeHCF/MWNT/GC electrode showed potent electrocatalytic activity toward the electrochemical oxidation of tryptophan in phosphate buffer solution (pH 7.0) with a diminution of the overpotential of 240 mV. The anodic peak currents increased linearly with the concentration of tryptophan in the range of 2.0 × 10⁻⁷ to 1.0 × 10⁻⁴ M with a detection limit of 2.0 × 10⁻⁸ M (at a S/N = 3). And the determination of tryptophan in pharmaceutical samples was satisfactory.     

碳热还原制备不同形貌的碳化硅纳米线

以酚醛树脂为碳源，正硅酸乙酯为硅源，硝酸镧和表面活性剂为调控剂，通过溶胶-凝胶和碳热还原反应制备了不同形貌的碳化硅纳米线。采用X射线衍射、扫描电子显微镜、透射电子显微镜和X射线散射能谱对所制备的碳化硅纳米线进行表征。结果表明，通过此方法所制备的碳化硅纳米线均为立方结构的β-SiC，分别具有直线状、竹节状和链珠状、分枝状等不同形貌。金属催化剂和表面活性剂对碳化硅纳米线的结构和形貌变化有重要影响。     

3-芳基-1-(吡啶-3-基)-2-(1H-1,2,4-三唑-1-基)-2-丙烯-1-醇的合成及生物活性研究

用硼氢化钠还原3-芳基-1-(吡啶-3-基)-2-(1H-1,2,4-三唑-1-基)丙烯酮, 合成了10个新型含吡啶基的三唑醇类化合物. 所有化合物均经核磁、元素分析确证. 生物活性测试结果表明, 部分化合物具有一定的杀菌活性及植物生长调节活性.     

新型含二茂铁有机配合物的合成及其电化学性质

以二茂铁为起始原料,经氯汞化反应、溴代反应、Suzuki偶联反应、水解反应和取代反应等5步反应合成了一种新型的含二茂铁结构单元的有机配合物(7),其结构经1H NMR、13C NMR、IR和HR-MS(ESI-TOF)表征。电化学研究结果表明:化合物6的E1/2小于化合物7,具有较高的氧化还原活性。     

以橡子为碳源制备的空心磁性碳纳米球及其吸附性能

以橡子为碳源,通过高温煅烧法制备了粒径均匀的磁性空心碳纳米球(MHCNS)。经过HCl浸泡处理可得MHCNS-1,再经HNO_3和NH_3·H_2O处理得MHCNS-2。MHCNS-2粒径均匀,直径为20～40 nm,球壁厚度为3～5 nm。MHCNS-2的尺寸可通过改变镍离子与氢氧化钾的添加量和比例进行调控。通过X射线粉末衍射、扫描电镜、透射电镜、振动样品磁强计等方法对制备的产物进行了表征,进而分析了其生长机制。MHCNS-2对于有机染料亚甲基蓝(MB)的吸附性能的实验结果表明,MHCNS-2具有强吸附性能,当MB溶液浓度为100 mg·L~(-1)时,吸附量可以达到185 mg·g~(-1)。MHCNS对布洛芬的载药释药实验结果表明,MHCNS-2载药率可达44%,释药率达70%,有着良好的载药与释药能力。     

Mild hydrothermal synthesis and magnetic properties of the manganates Pr1−xCaxMnO3

The calcium-doped manganates, Pr_1−xCa_xMnO₃ (x=0.39, 0.46, 0.70, 0.76), were synthesized as cube-shaped crystalline phases under mild hydrothermal conditions for the first time. The crystals could be grown in one step from solutions of metal salts and potassium hydroxide at temperatures ∼240 °C, and found to adopt perovskite-like structure (space group Pbnm). Samples were characterized by powder X-ray diffraction, scanning electron microscopy, inductively coupled plasma analysis and variable temperature dc/ac magnetic susceptibility. The studies indicate that formation of the materials is dependent on the alkalinity and composition of the initial reaction mixtures. The magnetic properties show spin-glass-like behavior due to competing ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions in Pr_1−xCa_xMnO₃ with x=0.39, 0.46.     

A Novel Carbon Nanotube-Supported NiP Amorphous Alloy Catalyst and Its Hydrogenation Activity

A carbon nanotube-supported NiP amorphous catalyst (NiP/CNT) was prepared by induced reduction. Benzene hydrogenation was used as a probe reaction for the study of catalytic activity. The effects of the support on the activity and thermal stability of the supported catalyst were discussed based on various characterizations, including XRD, TEM, ICP, XPS, H2-TPD, and DTA. In comparison with the NiP amorphous alloy, the benzene conversion on NiP/CNT catalyst was lower, but the specific activity of NiP/CNT was higher, which is attributed to the dispersion produced by the support, an electron-donating effect, and the hydrogen-storage ability of CNT. The NiP/CNT thermal stability was improved because of the dispersion and electronic effects and the good heat-conduction ability of the CNT support.     

旋转薄层色谱分离聚合物

报道了旋转薄层色谱分级聚合物，及配合直接扫描密度法测定分子量分布的结果．在旋转薄层硅胶板上用混合溶剂成功地分离并直接收集了聚苯乙烯２１个级分，分子量测定结果与ＧＰＣ法基本一致．初步认为旋转薄层色谱以薄层吸附色谱分离机理为基础，采用连续注入流动相和旋转薄层板离心力相结合的方式，改善并加快了分离效果