微孔板发光二极管诱导荧光-表面活性剂增敏法测定盐酸小檗碱

研制了微孔板发光二极管诱导荧光分析仪,以发光二极管为激发光源,Y形光纤束传导激发光和荧光,采用平面型光敏二极管接收荧光.采用二维定位器移动微孔板,可实现对多个样品快速连续的测定.利用弱碱性介质中阴离子表面活性剂十二烷基苯磺酸钠(SDBS)对盐酸小檗碱荧光的增敏作用,在pH 9.0的Britton-Robinson缓冲溶...     

恒电位自动滴定法分析脂肪酶水解活性影响因素

利用恒电位自动滴定法分析了脂肪酶(Candida rugosa lipase,CRL)催化橄榄油水解活性的影响因素,确定了适宜的酶活性测定条件,对比了传统表面活性剂和咪唑类离子液体对酶活性的影响.37 ℃时,与酶蛋白浓度呈线性关系的酶活性测定范围为1～14 μmol/min;酶蛋白浓度范围为0.01～0.07 g/L;...     

表面活性剂碳化法合成Fe3O4/C复合物及其电化学性能

以水热法合成的包覆油酸的α-Fe₂O₃粒子为前驱体, 在氩气下500 °C煅烧1 h, 得到Fe₃O₄/C纳米复合物. 用傅里叶变换红外(FTIR)光谱, X射线衍射(XRD), 扫描电镜(SEM), X射线能量散射(EDX)谱, 高分辨透射电镜(HRTEM), 元素分析, 循环伏安(CV)和恒流充放电测试等方法对材料的结构、形貌、成分及电化学性能进行了表征. 结果表明: 所制备的Fe₃O₄/C复合物呈长约200 nm, 粗约100 nm的纺锤形, 表面碳层厚约1-2 nm, 碳含量为1.956%(质量分数); 这种复合物作为锂离子电池负极材料具有很好的循环稳定性(在0.2C (1C=928 mA·g^-1)循环80次后具有691.7 mAh·g^-1比容量)和倍率性能(在2C循环20次后依然有520 mAh·g^-1比容量). 相对于未包覆的商业Fe₃O₄粒子, 复合物显著提高的电化学性能是由于碳包覆能防止粒子聚集, 提高导电性以及稳定固体电解质界面(SEI)膜.     

Effect of surfactant additives on nucleate pool boiling heat transfer of refrigerant-based nanofluid

Effect of surfactant additives on nucleate pool boiling heat transfer of refrigerant-based nanofluid was investigated experimentally. Three types of surfactants including Sodium Dodecyl Sulfate (SDS), Cetyltrimethyl Ammonium Bromide (CTAB) and Sorbitan Monooleate (Span-80) were used in the experiments. The refrigerant-based nanofluid was formed from Cu nanoparticles and refrigerant R113. The test surface is horizontal with the average roughness of 1.6 μm. Test conditions include a saturation pressure of 101.3 kPa, heat fluxes from 10 to 80 kW m⁻², surfactant concentrations from 0 to 5000 ppm (parts per million by weight), and nanoparticle concentrations from 0 to 1.0 wt.%. The experimental results indicate that the presence of surfactant enhances the nucleate pool boiling heat transfer of refrigerant-based nanofluid on most conditions, but deteriorates the nucleate pool boiling heat transfer at high surfactant concentrations. The ratio of nucleate pool boiling heat transfer coefficient of refrigerant-based nanofluid with surfactant to that without surfactant (defined as surfactant enhancement ratio, SER) are in the ranges of 1.12-1.67, 0.94-1.39, and 0.85-1.29 for SDS, CTAB and Span-80, respectively, and the values of SER are in the order of SDS > CTAB > Span-80, which is opposite to the order of surfactant density values. The SER increases with the increase of surfactant concentration and then decreases, presenting the maximum values at 2000, 500 and 1000 ppm for SDS, CTAB and Span-80, respectively. At a fixed surfactant concentration, the SER increases with the decrease of nanoparticle concentration. A nucleate pool boiling heat transfer correlation for refrigerant-based nanofluid with surfactant is proposed, and it agrees with 92% of the experimental data within a deviation of ±25%.     

不同形貌二水草酸钙对阴离子表面活性剂AOT的吸附差异

人体尿液中存在大量具有生物表面活性的物质,而这些物质与尿液中不同形貌的草酸钙微晶间的吸附关系并未得到人们广泛关注。挑选了常用的阴离子表面活性剂磺基琥珀酸钠二辛酯(AOT)作为吸附物质,研究了不同形貌的二水草酸钙(COD)晶体对AOT的吸附差异,探究草酸钙结石的形成机理。采用X射线粉末衍射仪(XRD)和傅里叶变换红外光谱仪(FTIR)表征,并通过谱图差异分析了吸附AOT前后棒状、圆钝形、花状、十字形和双锥形COD晶体的组分变化;采用Zeta电位分析仪测定吸附AOT后晶体表面的Zeta电位随AOT浓度的变化;采用比色法通过紫外可见分光光度计测定不同浓度AOT存在下晶体的吸附量变化并绘制吸附曲线。随着AOT浓度的增加,COD的吸附量逐渐上升,最后达到吸附饱和状态,各吸附曲线均呈S型。不同形貌COD对AOT的最大吸附量大小顺序为：棒状COD (41.0 mg·g-1)>圆钝形COD (37.5 mg·g-1)>花状COD (35.0 mg·g-1)>十字形COD (27.2 mg·g-1)>双锥形COD (20.9 mg·g-1)。COD晶体的比表面积越大,表面提供的活性位点也越多,越有利于表面活性剂AOT在晶体表面的吸附;富含Ca2+的(100)晶面更利于阴离子的AOT的优先吸附;此外COD晶体的内能越大,越会抑制AOT在COD表面的吸附,导致吸附量降低。吸附了AOT的COD晶体稳定性显著增加,COD向COM转变的速度明显降低。基于AOT在不同形貌的COD晶体表面的吸附特点,提出了COD晶体吸附AOT的分子模型。COD晶体对AOT的吸附与晶体形貌密切相关。容易吸附AOT的COD晶体形貌更容易粘附在带负电荷受损伤的细胞表面,加大草酸钙结石形成的风险。     

Inverted Micellar Enhanced Organic Peroxyoxalate Chemiluminescence

The use of neutral surfactant polyoxyethylene (9) dodecyl ether (AEO9) and polyoxyethylene (10) hexylphenol ether (TX-10) as an additive to enhance the chemiluminescence of peroxyoxalate reaction using bis(2-butoxycarbonyl-3,4,6-trichlorophenyl) oxalate (BBTPO) and hydrogen peroxide as the energy source in organic media with 9,10-diphenylanthracene as a fluorophore had been investigated. The oxidation of BBTPO in both AEO9 and TX-10 inverted micelles produced significantly improved intensity and efficiency of the chemiluminescence relative to that in normal organic media. It was found that in AEO9 and TX-10 inverted micellar media the enhancement of chemiluminescence was mainly due to the improvement of the reaction excitation efficiencies, but only slightly contributed by the increase of the fluorescence efficiency.     

微乳液进样火焰原子吸收光度法测定食品中的微量锰

研究了多种表面活性剂及微乳液对火焰原子吸收光谱法测定锰的增敏作用，并选择增敏作用最强的微乳液作为锰测定的增敏试剂，拟定了测定锰的新方法。     

Synthesis and surface properties of new semi-fluorinated sulfobetaines potentially usable for 2D-electrophoresis

New semi-fluorinated amidosulfobetaines, homologs of hydrocarbon amidosulfobetaines (ASB) commonly used in two-dimensional gel electrophoresis (2DE), were prepared in three steps from 2-F-alkylethyl iodide or F-alkyl iodide. Their synthesis was described and their air-water interface properties were investigated and compared with their perhydrogenated counterpart properties. The influence of the relative lengths of the perfluorinated and hydocarbonated moieties was discussed. 2DE of a rat testicular membrane fraction was performed comparatively using one of these fluorinated sulfobetaines and its hydrocarbon homolog; these preliminary results showed the great potential of the semi-fluorinated sulfobetaines in proteomic analysis.     

From dispersed nanodiscs to thin films of layered organic material via reversible swelling

We show that nanodiscs stabilized with polymers order and pile up on a surface upon drying. The resulting surface films with an average thickness of one micron are made of collapsed cohesive layers with smectic long-range order. This occurs with and without plastifying stabilizing polymer and produces crevasses. The stacked discs undergo a two-to-three-dimensional crystallization while bottom layers close to the surface fuse and produce infinite bilayers. Small angle X-ray scattering experiments demonstrate that excess polymer is segregated from the crystalline stack. Water adsorption isotherms show that reversible swelling of the excess polymer does not destroy the compact stack of partially fused nanodiscs collapsed parallel to the surface. In the absence of chemical binding, the stacks of layered nanodiscs can be removed by simple washing with pure water. AFM, TEM and SEM experiments demonstrate that presence of crevasses is quenched by the presence of a plastifying polymer.