Electrical potential oscillation in an anionic surfactant system with barbitone in octanol as an oil phase

Studies were made on oscillations across a liquid membrane consisting of an oil layer, octanol containing barbitone, between two aqueous layers: one containing 8 mM SDS with alcohol and the other containing 0.1 M NaCl. The effects of various concentrations of chemical components in this system on the patterns of electrical oscillation were examined. The oscillations may be explained by the mechanism of repetitive formation and destruction of monolayer structures of the dodecyl sulfate anion at the interface between the organic and the aqueous phases, with the effect of proton penetration. This study of potential oscillation across a membrane containing a drug provides the possibility of further investigations in pharmacological activity.     

破碎-絮凝法分离细长碳纳米管与碳纤维

根据碳纤维与细长碳纳米管耐磨性能与絮凝沉降性能的差异，提出了一种有效分离细长碳纳米管与碳纤维的物理方法——破碎-絮凝法.该方法包括研磨破碎、液相分散、絮凝沉降、过滤分离等步骤，可高效去除混杂于细长碳纳米管样品中的碳纤维，同时还可去除螺旋状碳纤维及细小碳颗粒等易悬浮杂质.纯化过程对细长碳纳米管无损伤.用电子显微镜和热重分析表征了纯化效果，并初步分析了纯化机理.     

芯片式流通池顺序注射可更新表面反射光谱法用于酶反应检测

将芯片式流通池顺序注射可更新表面反射光谱法用于酶反应检测。HRP催化H2O2氧化BPR底物的反应用于对H2O2的检测。此反应体系与葡萄糖氧化酶联用，用于对血清中葡萄糖的检测。     

Enantiomeric separation and quantification of fluoxetine (Prozac) in human plasma by liquid chromatography/tandem mass spectrometry using liquid-liquid extraction in 96-well plate format

Fluoxetine (Prozac) is currently one of the widely prescribed selective serotonin reuptake inhibitors (SSRIs) for the treatment of depression. A high-throughput sample preparation procedure using liquid-liquid extraction (LLE) in a 96-well plate format in conjunction with liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed and validated for quantification of fluoxetine enantiomers in human plasma. After addition of internal standard and ammonium hydroxide, samples were extracted with ethyl acetate. The organic extract was evaporated to dryness and reconstituted in methanol. Where possible, sample transfer and LLE steps were automated using a Tomtec Quadra 96 workstation. Adequate separation of fluoxetine enantiomeric pairs (resolution of 1.17) was achieved on a vancomycin column eluted with methanol containing 0.075% (by weight) ammonium trifluoroacetate. A triple quadrupole mass spectrometer, operated in the multiple reaction monitoring mode at m/z 310-->44 for fluoxetine enantiomeric pairs and m/z 287-->241 for oxazepam (internal standard), was used. Analysis was performed in the positive ion mode using atmospheric pressure chemical ionization (APCI). The standard curve range was 2.0-1000 ng/mL for each fluoxetine enantiomer. The intra- and inter-day precision and accuracy of the quality control (QC) samples were <12.5% (CV) and <13.6% (CV), respectively, for each fluoxetine enantiomer; the correlation coefficient was >0.990. Method ruggedness was demonstrated by the reproducible performance of the assay during a three-day validation period.     

Surface functionalization of ultrananocrystalline diamond films by electrochemical reduction of aryldiazonium salts

The surface functionalization of ultrananocrystalline diamond (UNCD) thin films via the electrochemical reduction of aryl diazonium cations is described. The one-electron-transfer reaction leads to the formation of solution-based aryl radicals, which in turn react with the UNCD surface forming stable covalent C-C bonds. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), ac impedance spectroscopy, and contact angle measurements have been employed to characterize the organic overlayer and estimate the surface coverage. The grafting of 3,5-dichlorophenyl groups renders the UNCD surface hydrophobic, whereas the attachment of 4-aminophenyl groups makes the surface relatively hydrophilic. The surface coverage, estimated from the electrochemical and XPS measurements, is as high as 70% of a compact monolayer. The aminophenyl terminated surface was obtained by electrochemical reduction of the tethered nitrophenyl groups. This two-step approach yields a UNCD surface with functional moieties available for the potential covalent coupling of a wide variety of biomolecules (e.g., DNA and proteins).     

负载型TiO2-聚酰亚胺亲水复合膜的制备与分离性能

采用溶解－流涎法，湿相转换法和干湿相转换法制轩了负载型ＴｉＯ２－聚酰亚胺亲水复合膜，采用扫描电镜，红外光谱，压汞和透气性实验等手段对该膜的孔径分布，表面结构及扩散性能进行了表征，并讨论了制备亲水对膜孔结构的影响，实验结果表明，三种膜均具有很好的亲水性能，而干湿相转换膜具有良好的孔径分布和分离性能。     

One-carbon chain extension of esters to alpha-chloroketones: a safer route without diazomethane

The reaction of a variety of methyl esters with dimethylsulfoxonium methylide at 0-25 degrees C affords the chain-extended beta-keto dimethylsulfoxonium ylides. Subsequent treatment with hydrogen chloride in THF proceeds with loss of DMSO to afford the corresponding alpha-chloroketones. This sequence has been utilized to convert the methyl esters of CBZ-protected alanine and valine to the anti N-protected alpha-amino epoxides, which are important pharmaceutical intermediates. When the same protocol is applied to BOC-protected phenylalanine methyl ester, epimerization occurs so that the use of a more reactive aryl ester is required. This chemistry provides a practical route to alpha-chloroketones that avoids the use of toxic and explosive diazomethane.     

A new series of pyrimidine-containing linear molecules: their elegant crystal structures and intriguing photophysical properties

A new series of aza-substituted analogues 3-5 based on the 1,4-bis(phenylethynyl)benzene moiety have been synthesized by the selective Pd-catalyzed Sonogashira coupling reaction from 5-bromo-2-iodopyrimidine (1). In these linear molecules, the dipolar pyrimidine moiety is introduced as a probe to investigate factors that control the intermolecular interactions over the crystal engineering. The results reveal that the manner of packing changes both dipolar interactions between linear pyrimidine-containing molecules and transition moments simultaneously, resulting in remarkably different photophysical properties. Due to their versatile dipole-dipole and face-to-face pi-piinteractions in a crystal motif, further applications on the design of ordered crystalline materials for the field effect transistors are promising.     

Cascade cyclizations via N,4-didehydro-2-(phenylamino)pyridine biradicals/zwitterions generated from enyne-carbodiimides

Thermolysis of the enyne-carbodiimides 7 having the central carbon-carbon double bond incorporated as part of the cyclopentene ring favors the formation of the corresponding N,4-didehydro-2-(phenylamino)pyridine intermediates, either as the sigma,pi-biradicals 8 or as the zwitterions 8', for subsequent synthetic elaborations. By placing appropriate substituents at the acetylenic terminus, a variety of the intramolecular decay routes are available for the initially formed sigma,pi-biradicals/zwitterions, leading to the 5,6-dihydrobenzo[c][1,8]naphthyridine 21, the 1,2,3,4-tetrahydro[1,8]naphthyridine 24 and related compounds 25 and 26, the 5,6-dihydrobenz[f]isoquinoline 28, and the benzofuro[3,2-c]pyridine 30. Surprisingly, the use of the dimethylamino group of the 2-(dimethylamino)phenyl substituent to capture the carbocationic center in the zwitterion 8e' furnished the 5H-pyrido[4,3-b]indole 32 in only 14% yield. The majority of the products were the 1H-pyrrolo[2,3-b]quinolines 34 and 35, isolated in 48 and 7% yields, respectively. However, it was possible to redirect the reaction toward 32 by conducting thermolysis of the enyne-carbodiimide 7e in the presence of 5 equiv of dimethylphenylsilyl chloride. Under this reaction condition, the 2-pyridone imine 37 was isolated in 86% yield, which on exposure to silica gel was converted to 32 in essentially quantitative yield. Thermolysis of the enyne-carbodiimide 42 having a methoxymethyl substituent at the acetylenic terminus led to the formation of 46' as a pyridine analogue of ortho-quinone methide imine. An intramolecular hetero-Diels-Alder reaction of 46' then furnished the tetrahydro[1,8]naphthyridino[2,1-c][1,4]benzoxazine 47.     

Asymmetric synthesis of 4,4-disubstituted-2-imidazoli-dinones: potent NK1 antagonists

[structure: see text] A highly efficient and practical synthesis of 4,4-Disubstituted-2-Imidazolidinones utilizing a "self-reproduction of the center of chirality" strategy is described.