Two-fluid electroosmotic flow in microchannels

This paper presents a mathematical model to describe a two-fluid electroosmotic pumping technique, in which an electrically non-conducting fluid is delivered by the interfacial viscous force of a conducting fluid; the latter is driven by electroosmosis. The electrical potential in the conducting fluid and the analytical solution of the steady two-fluid electroosmotic stratified flow in a rectangular microchannel was presented by assuming a planar interface between the two immiscible fluids. The effects of viscosity ratio, hold-up, concentration, and interfacial zeta potential are analyzed to show the potential feasibility of this technique.     

Quinine/selectfluor combination induced asymmetric semipinacol rearrangement of allylic alcohols: an effective and enantioselective approach to alpha-quaternary beta-fluoro aldehydes

A quinine/Selectfluor combination inducing rearrangement reaction of allylic alcohols was discovered, which involved a moderate yield with good enantioselective construction of alpha-quaternary carbon center and beta-fluoro aldehyde under base condition.     

Selective partial reduction of various heteroaromatic compounds with bridgehead nitrogen via Birch reduction protocol

[reaction: see text] For the first time various heteroaromatic compounds with bridgehead nitrogen, including indolizines, bispyrrolopyrimidines, pyrroloquinolines, pyrroloisoquinolines, and bispyrrolopyrazines, were selectively partially reduced under Birch reduction conditions. It was found that the double bond in the fused heterocycles which possesses the highest LUMO density can be selectively reduced under these conditions. Indolizine 6, containing an ester group at C-6, was reductively alkylated to give dihydroindolizines 8 and 9 possessing a quaternary carbon center in good yield. It was found that ambident substrate 12, under Birch reduction conditions, underwent smooth partial reduction to give 4,5-dihydroquinoline 14 as a sole product with no evidence of reduction of the side chain olefin. It was also shown that electron-rich pyrroloisoquinoline 15, which cannot be reduced via catalytic hydrogenation conditions, was efficiently transformed into its dihydrocounterpart 16 by using the Birch reduction protocol. Finally, it was shown that various fused diazines were smoothly and stereoselectively reduced under Birch reduction conditions to give trans-4,5-disubstituted dihydropyrimidines 30 and 32 in virtually quantitative yields.     

Infrared-visible and visible-visible double resonance spectroscopy of 1-hydroxy-9,10-anthraquinone-(H2O)n (n=1,2) complexes

The structures of hydrated 1-hydroxyanthraquinone complexes (1-HAQ), 1-HAQ(H2O)n=1,2, with intramolecular and intermolecular hydrogen bonding interactions were studied using laser spectroscopic methods such as laser induced fluorescence, fluorescence-detected infrared, infrared-visible hole burning, and visible-visible hole burning spectroscopy. In the 1:1 complex 1-HAQ(H2O)1, the water binds to the free carbonyl group of 1-HAQ not associated with intramolecular hydrogen bond. The second water in the 1:2 complex, 1-HAQ(H2O)2, binds to the first water of the 1:1 complex rather than other hydrogen bonding sites of 1-HAQ. A pair of two geometric isomers was produced in a supersonic jet for each of the 1:1 and 1:2 complexes. Both isomers of each complex have the same vibrational spectra in the region of the OH stretching vibration of water, but have different energies for the 0-0 band of vibronic transition due to the asymmetry of the two phenyl rings in 1-HAQ. The 0-0 bands for all four species of 1-HAQ(H2O)n=1,2 were unambiguously assigned by comparing with the results of ab initio calculations, which yielded the structures, vibrational frequencies, and relative energies of the frontier molecular orbitals.     

Optimum conditions for preparing micron-sized PMMA beads in the dispersion polymerization using PVA

The optimum conditions for preparing micron-sized monodisperse polymethylmethacrylate (PMMA) beads by dispersion polymerization in a methanol/water mixture were proposed. PMMA forming microspheres having an average molecular weight of 55,300 g/mol, 2.6 μm weight-average diameter, with a 5.3% coefficient of variation and 91% conversion, were successfully obtained in the presence of 15 wt.% of polyvinylalcohol (PVA), 100/50 (g/g) of MeOH/water mixtures at 70°C; the reaction lasted for 8 h. Compared to dispersion polymerization using polyvinylpirrolydone, PVA proved to be an extremely stable steric stabilizer in the dispersion polymerization of methylmethacrylate.     

新型重整催化剂的研究—Pt／BaKL型沸石中钡的作用

本文采用XRD,NH_3-TPD,IR以及TEM等方法考察了Pt/BaKL沸石中Ba~(2+)的作用。NH_3-TPD结果表明,交换Ba~(2+)后的L型沸石的酸性,由于阳离子的作用仅在弱酸范围内有些改变,但与载铂的沸石的催化活性无明显的对应关系。IR及XRD谱线表明,BaKL沸石中Ba~(2+)在最佳交换度(26.3%)时,随预培烧温度的提高,使Ba~(2+)处于沸石孔道中B、C、D位置,接近于最佳分布,此时IR谱线上1421cm~(-1)处有一新峰。当沸石负载铂后,因铂与Ba~(2+)的相互作用,新峰消失,导致铂粒在沸石上分布更加均匀;铂粒在1.5—3.0nm之间占有最大比例,使得Pt/BaKL沸石呈现芳构化活性及选择性高于Pt/KL沸石,分别为～98%和～95%。     

Biopolymer and carbon nanotubes interface prepared by self-assembly for studying the electrochemistry of microperoxidase-11

Stable films of biopolymer chitosan and carbon nanotubes were prepared by a layer-by-layer self-assembly technique. Atomic force microscopy, scanning electron microscopy, cyclic voltammetry, and UV-vis spectroscopy were used to characterize the film assembly. Atomic force microscopy and scanning electron microscopy showed that an even, stable film was formed. The UV-vis spectroscopy and cyclic voltammetry study indicated the uniform growth of the film. The property of the self-assembled multilayer film in promoting protein electron transfer was demonstrated by incorporating microperoxidase-11 in the film. Microperoxidase-11 in the multilayer film could transfer electrons with the electrode indicating that carbon nanotubes could wire the protein to the electrode. The electrocatalytic activity of the microperoxidase-11 containing multilayer film-modified electrode toward H(2)O(2) and O(2) was investigated. The results showed that along with the increase in the assembled layers the electrocatalytic reduction potentials of H(2)O(2) and O(2) shifted positively. The prepared multilayer film of chitosan and carbon nanotubes containing protein was a sensitive interface for electrocatalytic study.     

N,N（二甲庚基）乙酰胺萃钯机理研究

本文研究了N,N二甲庚基乙酰胺(N_(s03))从氯化物体系中萃取钯的机理。应用等摩尔系列法和斜率法确定萃合物组成为:(CH_3CONR_2H)_2PdCl_4。通过紫外-可见光谱法研究,证实N_(503)萃取钯的机理属阴离子交换反应,其萃取方程式为: 2CH_3CONR_2HCl_((o)) PdCl_4~(2-)(a)?(CH_3CONR_2H)_2PdCl_4(o) 2Cl~-(a)     

Effects of allyl sulfur compounds and garlic extract on the expression of Bcl-2, Bax, and p53 in non small cell lung cancer cell lines

Allyl sulfur compounds play a major role in the chemoprevention against carcinogenesis. The present study compared the antiproliferative effects of diallyl sulfide (DAS), diallyl disulfide (DADS) and garlic extract on p53-wild type H460 and p53-null type H1299 non small cell lung cancer cells (NSCLC). The DAS and DADS treatment of both H460 and H1299 cells resulted in the highest numbers of cells in apoptotic state as measured by acridine orange staining, however, garlic extract treatment did not induce any significant apoptotic cells by MTT assay. DADS was found to be more effective in inducing apoptosis on NSCLC. The level of p53 protein in H460 cell was increased following DADS treatment. DAS and garlic extract treatment of H460 cells induced a rise in the level of Bax and a fall of Bcl-2 level. These results demonstrate that DAS, DADS and garlic extract are effective in reduction of anti-proliferative gene in NSCLC and suggest that modulation of apoptosis-associated cellular proteins by DAS, DADS and garlic extract may be the mechanism for apoptosis which merit further investigation as potential chemoprevention agents.     

A facile and convenient synthesis of 3-alkylamino-5-arylthiophenes with a variety of substituents at C-2 and studies of reaction mechanisms

Thioaroylketene S,N-acetals were treated with active methylene compounds including beta-keto ester, nitromethane, cyanoacetic acid, p-toluenesulfonylacetone, 4-nitrophenylacetic acid, and diethyl (2-oxopropyl)phosphonate in the presence of mercury(II) acetate in CH(2)Cl(2) at room temperature. These reactions gave 3-alkylamino-5-arylthiophenes containing various substituents, which comprised, respectively, alkoxycarbonyl, nitro, cyano, p-toluenesulfonyl, 4-nitrophenyl, and diethylphosphono groups at C-2 in good yields. The reaction of 3-methylamino-3-methylthio-1-phenylthioxopropene with malonic acid or Meldrum's acid under the same conditions gave 3-methylamino-5-phenylthiophene. Similarly, treatment of 3-methylamino-3-methylthio-1-phenylthioxopropene with various enolizable cyclic ketones such as 4-hydroxy-6-methyl-2-pyrone, homophthalic anhydride, 2-hydroxy-1,4-benzoquinone, and 1, 3-diethyl-2-thiobarbituric acid gave thieno[3,2-b]pyridin-4-one, thieno[3,2-c]isoquinolin-5-one, thieno[3,2-c]benzazepine-1,6-dione, and thieno[3,2-d]pyrimidine-2,4-dione, respectively.