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        검색결과 26

        21.
        2003.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We studied electrochemical characteristics of Langmuir-Blodgett(LB) films by using cyclic voltammetry with a three-electrode system. An Ag/AgCl as a reference electrode, a platinum wire as a counter electrode and LB film-coated indium tin oxide(ITO) as a working electrode were used to study electrochemical characteristics at a various concentration of NaClO4 solution. LB films were reduced from initial potential to -1350 mV, continuously oxidized to l650mV and returned to the initial point. The scan rate was l00mV/s. The monolayer surface morphology of the LB film have been measured by Atomic Force Microscope(AFM). As a result, We comfirmed that the microscopic properties of LB film by AFM showed the good orientation of momolayer molecules and the thickness of monolayer was 3.5-4.lnm. The cyclic voltammograms(CV) of the ITO-coated glass showed the peak potentials for the reduction-oxidation reation. LB films of 4-octyl-4'-(5-carboxypentamethyleneoxy) azobenzene(8A5H) / L-α-phosphayidyl choline, dilauroyl(DLPC) seemed to be irreversible process caused by only the oxidation current from the cyclic voltammogram. The current of oxidatation increased at cyclic voltammogram by increasing 8A5H density in LB films. The diffusivity(D) of LB films increased with increasing of a 8A5H amount and was inversely proportional to the concentration of NaClO4 solution.
        4,000원
        22.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        CaCO3 absorbed sodium lauryl sulfate (SLS) surfactant was prepared, Core-shell polymers of inorganic/organic pair, which have both core and shell component, were synthesized by sequential emulsion polymerization using styrene(St) as a shell monomer and potasium persulfate (KPS) as an initiator, We found that when CaCO3; core prepared by adding 2,0 wt% SLS, CaCO3 core/PSt shell polymerization was carried out on the surface of CaCO3 particle without forming the new PSt particle during St shell polymerization in the inorganic/organic core-shell polymer preparation, The structure of core-shell polymer were investigated by measuring the degree of decomposition of CaCO3 using HCl solution, thermal decomposition of polymer composite using thermogravimetric analyzer and morphology by scanning electron microscope.
        4,000원
        23.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We carried out this subject to observe photoisomerization using 1,2-dioleoyl-sn- glycero-3-phosphocholine(DOPC) mixed with fatty acid containing azobenzene group which has reversible to cis-trans by light irradiation. Spreading solutions for the LB films were prepared in chloroform(5.0×10-5mol/L).We investigated the photoisomerization and property of the organic ultra thin film of fatty acid containing azobenzene was prepared on the hydrophilic ITO(idium tin oxide) glass plate by LB method. As a result, the absorption spectra of 8A5H and DOPC of mixture LB films was induced to photoisomerization by alternating irradiation of ultraviolet and visible light, because the condensation of pure azobenzene monolayers was loosened by the introduction of phospholipid into the monolayers, and the molecular high aggregation in pure azobenzene monolayers is also weakened by the introduction of phospholipid. We found that it was reversibly induced to cis-trans photoisomerization in several solvents and mixture LB films.
        4,000원
        24.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Copolymerization of α-Methylstyrene(AMS) with Acrylonitrile(AN) was carried out with benzoylperoxide(BPO) as an initiator in toluene at 80℃ in a continuous stirred tank reactor. Reaction volume and residence time were 0.6 liters and 3 hours, respectively. The monomer reactivity ratios, rAMS and rAN determined by both the Kelen-Tüdös method and the Fineman-Ross method were rAMS=0.16(0.14), rAN=0.04(0.06). The cross-termination factor Φ of the copolymer over the entire AMS composition ranged from 0.75 to 0.92. The Φ factors of poly(AMS-co-AN) were increased with increasing AMS content. The simulated conversions and copolymerization rates were compared with the experimental results. It was observed that the average time to reach dynamic steady-state was three times the residence time.
        4,000원
        25.
        2001.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To prepare an acrylic type pressure-sensitive adhesive, quarternary polymers were synthesized from butyl acrylate (BA), 2-ethyl hexyl acrylate (2-EHA), methyl methacrylate (MMA), and 2-hydroxy ethyl methacrylate (2-HEMA). The quarternary polymers were identified by FT-IR and Molecular weight was measured by Gel Pearmeation Chromatography. Also, viscosity, solid content and peel strength were examined. The peel strength was 160 gf/25 mm when the volume ratio of feed monomer to solvent was 1.3:1, and the ratio was relevant to commercial usage. The pot life of adhesive was 30 sec at the 50 m/min of heat treatment rate at, and it indicated that the minimum drying time was 30 sec. In weathering resistance test, peel strength of 160~180 gf/25 mm after 1000 h, with no residual remains on the adhesive surface.
        4,000원
        26.
        2018.02 KCI 등재 서비스 종료(열람 제한)
        Background: This present study was conducted to evaluate the anti-inflammatory and immune regulatory effects of Aucklandia lappa Decne (AL). Methods and Results: We measured cytotoxicity, nitric oxide (NO) content, mRNA expression (iNOS, IL-1α, IL-1β, and TNF-α), protein expression (iNOS, COX-2, and IκB-α) and phagocytic activity in RAW264.7 cells. Male BALB/c mice were fed 100 ㎎/㎏ AL (Aucklandia lappa Decneon 70% ethanol extract) and 250 ㎎/㎏ AL for 4 weeks; thereafter, we observed B/T or CD4+/CD8+ lymphocyte subpopulation change, and expression patterns of CD4+ and CD8+ lymphocytes by immunohistochemical staining in mouse splenocytes and/or thymocytes. To determine the experimental concentration of AL, cell viability was measured by MTT assay and tested at 12.5 ㎍/㎖ or less. AL inhibited the levels of NO, lymphokine production (IL-1β, and TNF-α), and mRNA (iNOS, IL-1α, IL-1β, and TNF-α) and protein (iNOS, and COX-2) expression. Additionally, the levels of IκB-α, phagocytic activity, and splenic and thymic T lymphocytes, especially TH and TC cells were significantly increased in AL administered mice. The immuno-reactive density of CD4+ and CD8+ lymphocytes was stronger in AL groups than in the normal group. AL stimulated NO, iNOS, and COX-2, and regulated IL-1α, IL-1β, TNF-α, and IκB-α in macrophages treated with LPS (lipopolysaccharide). In addition, AL increased the phagocytic activity of macrophages and the immunity of mouse T (TH, and TC) cells. Conclusions: These results suggested that AL might show anti-inflammatory activity via the suppression of various inflammatory markers and immuno-regulatory activity.
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