Pseudo Peak Phenomena in Micellar Electrokinetic Capillary Chromatography by Using Ionic Surfactant

The origin of pseudo peak was studied by means of micellar electrokinetic capillary chromatography with cetyltrimethylaminium bormide as the pseudo stationary phase.It has been pointed that two peaks may appear for one component under certain conditions.Experiments showed that the relative areas of the two peaks of analyte depended on the time and the temperature of reaction between analyte and surfactant,and the concentration of surfactant in the sample solution.It means that the interaction between the analyte and the surfactant is a slow process,and a stable substance can be produced from the interaction.It is the substance and the analyte that may lead to the formation of two peaks.The fast interaction mechanism between the solute and the micellar should be queried from the experiment result.     

毛细管区带电泳法分离发酵液中的木糖和木糖醇

 建立了利用毛细管区带电泳分离发酵液中木糖和木糖醇的新方法。研究表明 :采用硼砂缓冲溶液时 ,木糖和木糖醇的分离度随硼砂浓度的增高而加大 ,在室温下硼砂最高浓度为 130mmol/L ;分离度还与溶液的 pH有关 ,在pH 9 5 5处分离度有最大值 ;缓冲液中十六烷基三甲基溴化铵的浓度为 4× 10 -6mmol/L～ 8× 10 -4 mmol/L时对分离度无显著影响 ;在优化的分离条件下 ,木糖和木糖醇可在 6min内基线分离。测定了发酵过程中样品各组分的含量和加标回收率 ,5次测定木糖的相对标准偏差 (RSD)为 1 42 %～ 3 11% ,回收率为 96 0 %～ 10 8 0 % 。     

Speciation in atomic spectrometry—an oxymoron?

Because atomic spectrometry inherently involves the decomposition of a sample into its constituent atoms, it inevitably destroys speciation information. Only by combining an atomic spectrometric method withan auxiliary, species-specific technique, or by modifying the ‘atomic’ spectrometer substantially, can speciation by ascertained. In this brief paper, three alternative approaches to speciation are outlined. Among them, the use of a switched or modulated source seems particularly appealing.     

磁化水技术在电感耦合等离子体-原子发射光谱法中的应用

考察了被测元素谱线强度随磁感应强度的变化情况.在优化磁感应强度0.24T条件下,研究了搅拌条件下样品溶液磁化时间对谱线强度及信背比的影响.经过测量自来水样品中元素Zn、Fe、Mg(I、I)、Si、V谱线强度表明,在对水样品进行搅拌磁化时,所测元素的谱线强度及信背比均有所增大;当水样品被磁化处理3h,上述元素的谱线强度分别比未磁化时增加了42.2%、97.9%、10.4%、10.1%、81.2%和28.8%,而且元素Zn、Fe、Si和V的信背比也分别增加了13.8%、86.9%、64%和28.8%,有利于降低光谱分析检出限.     

甲胺磷人工抗原的合成及光谱表征

通过化学方法合成了一种甲胺磷的半抗原6-(O,O-二甲基硫代磷酰基)氨基己酸(MC),MC与N-羟基琥珀酰亚胺(NHS)反应得到6-(O,O-二甲基硫代磷酰基)氨基己酸活化酯(MCE),活化酯(MCE)与匙孔血兰蛋白(KLH)偶联得到第一种人工抗原(MC-KLH);直接用甲胺磷作为半抗原用重氮化法与牛血清蛋白(BSA)偶联得到第二种人工抗原(M-BSA)。通过质谱、红外和核磁表征,证明所合成的半抗原是设计的目标产物;并且对两种人工抗原进行了红外光谱分析,结果表明,人工抗原1的红外光谱中既有酰胺结构单元又有半抗原中的甲氧结构单元;半抗原2中不但具有酰胺结构单元又有甲胺磷的甲氧基和硫氧基结构单元,以此判断半抗原和蛋白偶合成功,为红外光谱法用于人工抗原合成与否的鉴定研究提供了依据。     

应用荧光猝灭法研究尼莫地平与牛血清白蛋白的相互作用

应用荧光光谱(FS)和紫外光谱(UV)研究了尼莫地平与牛血清白蛋白(BSA)之间的相互作用。尼莫地平与BSA的结合常数K_A为5.01×104(26 ℃)和4.46×104(36 ℃),尼莫地平在BSA上的结合位点数为1.08±0.01。根据Frster非辐射能量转移理论,求出了尼莫地平与BSA之间的结合距离为3.14 nm(26 ℃)和3.10 nm(36 ℃)。实验表明静态猝灭和非辐射能量转移是 导致尼莫地平对BSA荧光猝灭的两大原因。通过计算热力学参数,可知该药物与牛血清白蛋白的相互作用是一个吉布斯自由能降低的自发过程,且二者之间的作用力以静电相互作用为主。     

Transfer Hydrogenation of Nitroarenes Catalyzed by CoCu Anchored on Nitrogen-doped Porous Carbon

The non-precious metal catalysts with high catalytic activity is extremely desirable but still full of challenges. In this paper, CoCu bimetal immobilized on nitrogen-doped porous carbon (CoCu-N-C) was prepared by an effective ligand-stabilized pyrolysis strategy. CoCu-N-C exhibited excellent catalytic efficiency for the transfer hydrogenation of nitroarenes with ammonia borane as hydrogen source, which can be ascribed to the well dispersed metal nanoparticles, the synergetic interaction of CoCu bimetal and nitrogen-doped carbon. The durability and recyclability experiments of the recycled CoCu-N-C catalyst indicated that no obvious change in catalytic performance was observed after five consecutive cycles. To gain insight into the catalytic mechanism of CoCu-N-C for the hydrogenation reaction, density functional theory calculations was also conducted. This work provides an universal approach for constructing highly efficient non-precious metal heterogeneous catalysts and which may find diverse high performance applications.     

Understanding the mechanisms of cancers based on function sub-pathways

Pathway analysis has become a popular technology tool for gaining insight into the underlying biology of differentially expressed genes and proteins. Although many sub-pathways analysis methods have been proposed, the function of these sub-pathways is generally implicit. In this paper, we propose a function sub-pathway analysis (FSPA) method which includes all nodes reaching a specific function node at the downstream of pathways. The perturbation degree of a sub-pathway is defined as the negative of the log p-value of the sub-pathway. The proposed FSPA allows analyzing the differentially expressed genes in a sub-pathway with diseases in explicit function level. Results from six datasets of colorectal cancer, lung cancer and pancreatic cancer show that the proposed FSPA could identify more cancer associated pathways. And more importantly, it could identify which sub-pathways lead to a specific abnormal function, and to what extent it affects the function. Furthermore, the proposed perturbation degree could also analyze the imbalance of some functions involved in some biological process. The results by FSPA are helpful for elucidating the underlying mechanisms of cancers and designing therapeutic strategies.     

Ultrasound-assisted surfactant-enhanced emulsification microextraction for the determination of carbamate pesticides in water samples by high performance liquid chromatography

A novel ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) coupled with high performance liquid chromatography-diode array detection has been developed for the extraction and determination of six carbamate pesticides (metolcarb, carbofuran, carbaryl, pirimicarb, isoprocarb and diethofencarb) in water samples. In the UASEME technique, Tween 20 was used as emulsifier, and chlorobenzene and chloroform were used as dual extraction solvent without using any organic dispersive solvent that is normally required in the previously described common dispersive liquid–liquid microextraction method. Parameters that affect the extraction efficiency, such as the kind and volume of the extraction solvent, the type and concentration of the surfactant, ultrasound emulsification time and salt addition, were investigated and optimized for the method. Under the optimum conditions, the enrichment factors were in the range between 170 and 246. The limits of detection of the method were 0.1–0.3 ng mL⁻¹ and the limits of quantification were between 0.3 and 0.9 ng mL⁻¹, depending on the compounds. The linearity of the method was obtained in the range of 0.3–200 ng mL⁻¹ for metolcarb, carbaryl, pirimicarb, and diethofencarb, 0.6–200 ng mL⁻¹ for carbofuran, and 0.9–200 ng mL⁻¹ for isoprocarb, with the correlation coefficients (r) ranging from 0.9982 to 0.9998. The relative standard deviations varied from 3.2 to 4.8% (n = 5). The recoveries of the method for the six carbamates from water samples at spiking levels of 1.0, 10.0, 50.0 and 100.0 ng mL⁻¹ were ranged from 81.0 to 97.5%. The proposed UASEME technique has demonstrated to be simple, practical and environmentally friendly for the determination of carbamates residues in river, reservoir and well water samples.     

大豆苷元与人血清白蛋白的相互作用研究

采用荧光猝灭光谱、同步荧光光谱和紫外-可见吸收光谱,研究了大豆苷元与人血清白蛋白（HSA）之间的结合反应。大豆苷元对人血清白蛋白有较强的荧光猝灭作用,猝灭机制属于静态猝灭,并发生了分子内非辐射能量转移。利用Stern-Volmer方程处理实验数据,得到大豆苷元与HSA之间的结合常数KA为0.34×10^4（23 ℃）,1.10×10^4（30 ℃）和4.36×104 L·mol^-1（40 ℃）。根据Forster非辐射能量转移理论,求出了大豆苷元与HSA之间的结合距离为1.50 nm（23 ℃）,1.46 nm（30 ℃）和1.42 nm（40 ℃）。通过计算相应的热力学参数,可知大豆苷元与人血清白蛋白的相互作用是一个吉布斯自由能降低的自发过程,且二者之间的主要作用力类型为疏水作用力,同时用同步荧光光谱考察了大豆苷元对HSA构象的影响。