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91.
Won Young Jung Seung Hee Baek Seong Soo Park Gun-Dae Lee Euh Duck Jeong Hyun Gyu Kim Seong-Soo Hong 《Reaction Kinetics and Catalysis Letters》2007,91(2):233-240
The nanosized titania and TiO2/SiO2 particles were prepared by the microwave-hydrothermal method. The effect of physical properties TTIP/TEOS ratio and calcination
temperature has been investigated. The major phase of the pure TiO2 particle is of the anatase structure, and a rutile peak was observed above 800°C. In TiO2/SiO2 particles, however, no significant rutile phase was observed, although the calcination temperature was 900°C. No peaks for
the silica crystal phase were observed at either silica/titania ratio. The crystallite size of TiO2/SiO2 particles decreases as compared to pure TiO2 at high calcination temperatures. The TiO2/SiO2 particles show higher activity on the photocatalytic decomposition of orange II as compared to pure TiO2 particles. 相似文献
92.
Abstract— C4 -- Photocycloaddition of 5,7-dimethoxycoumarin (DMC) to thymine (λ≥ 300 nm) was studied in dioxane-water solution, in aqueous frozen state, and solid film state. The major product was isolated and characterized by physical methods. Elemental analysis data, spectral analyses, and photo-splitting of the product indicate the product to be a 1:l C4 -- cycloadduct of DMC and thymine. 相似文献
93.
Abstract— The photocycloaddition reaction of 5,7-dimethoxycoumarin to thymidine on direct irradiation (λ > 300 nm) is studied as a model for photosensitization reaction of furocoumarins. The major photoadducts were isolated by silica gel column and gel permeation chromatography. Each component of the photoadducts was further separated by reverse phase, paired-ion high performance liquid chromatography. The structure of these photoproducts isolated is consistent with 1:1 C4 -cycloadducts in accordance with characteristics of their UV, IR, NMR and mass spectra and elemental analysis data. The stereochemistry of each isomer was studied by Fourier transform NMR, UV and IR spectra. The fraction C has the anti head-to-tail configuration and the fraction D has the configuration of anti head-to-head. The fractions A and B probably have the syn configuration. 相似文献
94.
Nam W Oh SY Sun YJ Kim J Kim WK Woo SK Shin W 《The Journal of organic chemistry》2003,68(20):7903-7906
The catalytic epoxidation of cyclohexene by iron(III) porphyrin complexes and H2O2 has been investigated in alcohol solvents to understand factors affecting the catalyst activity in protic solvents. The yields of cyclohexene oxide and the Fe(III/II) reduction potentials of iron porphyrin complexes were significantly affected by the protic solvents, and there was a close correlation between the product yields and the reduction potentials of the iron porphyrin catalysts. The role of alcohol solvents was proposed to control the electronic nature of iron porphyrin complexes that determines the catalyst activity in the epoxidation of olefins by H2O2. We have also demonstrated that an electron-deficient iron porphyrin complex can catalyze the epoxidation of olefins by H2O2 under conditions of limiting substrate with high conversion efficiency in a solvent mixture of CH3OH and CH2Cl2. 相似文献
95.
Kim K Shin K Kim H Kim C Byun Y 《Langmuir : the ACS journal of surfaces and colloids》2004,20(13):5396-5402
We have prepared a chemically anchored monolayer of PEG (poly(ethylene glycol)) and phospholipid mixture (PEG/phospholipid) on a methacryloyl-terminated substrate by in situ photopolymerization. Both monoacryloyl phospholipid (acryloyl-PC, 1-palmitoyl-2-[12-(acryloyloxy)dodecanoyl]-sn-glycero-3-phosphocholine) and monoacryloyl PEG (acryloyl-PEG, 12-(acryloyloxy)dodecanoyl-PEG) were synthesized by modifyingphospholipid and PEGwith 12-(acryloyloxy)-1-dodecanoic acid and 12-(acryloyloxy)-1-dodecanol, respectively. The surface pressure-area (pi-A) isotherm showed that acryloyl-PEG molecules were stable in the phospholipid monolayer and that they could be evenly inserted into a phospholipid monolayer at the air/water interface. By adding 10 mol % acryloyl-PEG into phosholipid vesicles, we could produce a PEG/phosholipid monolayer on methacryloyl-terminated substrates using vesicle fusion for 3 h. Then, this polymerizable PEG/phospholipid monolayer was in situ photopolymerized onto a methacryloyl-terminated substrate with eosin Y/triethanolamine as co-initiators. Optimal vesicle fusion and irradiation condition were determined with respect to the vesicle fusion time and duration of irradiation. As confirmed by atomic force microscopy and X-ray reflectivity studies, the polymerized PEG/phosholipid surface formed a PEG-covered phospholipid monolayer with thicknesses of 3 and 6 nm for the base phospholipid monolayer and the covering PEG layer, respectively. The chemical anchoring efficiency ofpolymerized PEG and phospholipid molecules, which was calculated by the relative carbon ratio of each surface before and after methanol washing using X-ray photoelectron spectroscopy, was 98%. This polymerized PEG/phosholipid monolayer showed good stability in organic solution due to firm chemical anchoring to a solid surface. 相似文献
96.
Lee CS Kim KY Im JB Choi JW Kim HK Park JS Shin EY Kim SR Kim EG 《Experimental & molecular medicine》2004,36(6):582-587
p21-activated kinase (PAK)-interacting exchange factor (PIX) is known to be involved in regulation of Cdc42/Rac GTPases and PAK activity. PIX binds to the proline-rich region of PAK, and regulates biological events through activation of Cdc42/Rac GTPase. To further investigate the role of PIX we produced monoclonal antibodies (Mab) against bPIX. Three clones; N-C6 against N-terminal half and C-A3 and C-B7 against C- terminal half of bPIX were generated and characterized. N-C6 Mab detected bPIX as a major band in most cell lines. C-A3 Mab recognizes GIT-binding domain (GBD), but it does not interfere with GIT binding to bPIX. Using C-A3 Mab possible bPIX interaction with actin in PC12 cells was examined. bPIX Mab (C-A3) specifically precipitated actin of the PC12 cell lysates whereas actin Mab failed to immunoprecipitate bPIX. Co-sedimentation of PC12 cell lysates with the polymerized F-actin resulted in the recovery of most of bPIX in the cell lysates. These results suggest that bPIX may not interact with soluble actin but with polymerized F-actin and revealed that bPIX constitutes a functional complex with actin. These data indicate real usefulness of the bPIX Mab in the study of bPIX role(s) in regulation of actin cyoskeleton. 相似文献
97.
Tadahiro Kato Motoyuki Tanaka Shin‐suke Takagi Keita Nakanishi Masahiro Hoshikawa 《Helvetica chimica acta》2004,87(1):197-214
The synthesis of kempa‐6,8‐dien‐3β‐ol ( 4a ), as a synthetic leading model of the natural product 4b , was carried out starting from intermediate 12 , the synthetic route of which has been developed previously (Scheme 1). The conversion of 12 to the model compound 4a involved the elaboration of three structure modifications by three processes, Tasks A, B, and C (see Scheme 2). Task A was achieved by epoxy‐ring opening of 41 with Me3SiCl (Scheme 9), and Task B being performed by oxidation at the 13‐position, followed by hydrogenation, and then epimerization (Schemes 4 and 5). The removal of the 2‐OH group from 12 (Task C) was achieved via 30b according to Scheme 6, whereby 30b was formed exclusively from 30a / 31a 1 : 1 (Scheme 7). In addition, some useful reactions from the synthetic viewpoint were developed during the course of the present experiments. 相似文献
98.
The pretreatment of waste-activated sludge (WAS) by electron beam irradiation was studied in order to improve anaerobic sludge
digestion. The irradiation dose of the electron beam was varied from 0.5 to 10 kGy. Batch and continuous-flow stirred tank
reactors (CFSTRs) were operated to evaluate the effect of the electron beam pretreatment on anaerobic sludge digestion. Approximately
30–52% of the total chemical oxygen demand (COD) content of the WAS was solubilized within 24 h after electron beam irradiation.
A large quantity of soluble COD, protein, and carbohydrates leached out from cell ruptures caused by the electron beam irradiation.
Volatile fatty acids production from the irradiated sludge was approx 90% higher than that of the unirradiated sludge. The
degradation of irradiated sewage sludge was described by two distinct first-order decay rates (k
1 and k
2). Most initial decay reaction accelerated within 10 d, with an average k
1 of 0.06/d for sewage sludge irradiated at all dosages. The mean values for the long-term batch first-order decay coefficient
(k
2) were 0.025/d for irradiated sewage sludge and 0.007/d for unirradiated sludge. Volatile solids removal efficiency of the
control reactor fed with unirradiated sewage sludge at a hydraulic retention time (HRT) of 20 d was almost the same as that
of the CFSTRs fed with irradiated sludge at an HRT of 10 d. Therefore, disintegration of sewage sludge cells using electron
beam pretreatment could reduce the reactor solid retention time by half. 相似文献
99.
To isolate epigallocatechin gallate (EGCG) of catechin compounds from Korean green tea (Bosung, Chonnam), a C18 reversed-phase preparative column (250x22 mm) packed with packings of three different sizes (15, 40-63, and 150 microm) was used. The sample extracted with water was partitioned with chloroform and ethyl acetate to remove the impurities including caffeine. The mobile phases in this experiment were composed of 0.1% acetic acid in water, acetonitrile, methanol and ethyl acetate. The injection volume was fixed at 400 microl and the flow rate was increased as the particle size becomes larger. The isolation of EGCG with particle size was compared at a preparative scale and the feasibility of separation of EGCG at larger particle sizes was confirmed. The optimum mobile phase composition for separating EGCG was experimentally obtained at the particle sizes of 15 and 40-63 microm in the isocratic mode, but EGCG was not purely separated at the particle size of 150 microm. 相似文献
100.
Effective isolation of magnesium lithospermate B and its inhibition of aldose reductase and fibronectin on mesangial cell line 总被引:4,自引:0,他引:4
Jung M Lee HC Ahn CW Park W Choi S Kim H Cho D Lee GT Li HR 《Chemical & pharmaceutical bulletin》2002,50(8):1135-1136
We developed an effective isolation method of magnesium lithospermate B from Salviae miltiorrhizae Radix and found for the first time that magnesium lithospermate B shows strong in vitro inhibition (IC50=0.04 microM) of aldose reductase (AR), 2.5 times than that of clinically used epalrestat (IC50=0.1 microM) and accumulation of fibronectin dose dependently. 相似文献