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        검색결과 99

        63.
        2005.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        IASL(iodo acetamide) and MSL(maleimide) disordered the orderly helix arrangement of myosin in the rest state of spin level. Especially the effect of IASL was great. Equatorial refiection(10,11) change inferred that myosin head was moved to the vicinity of actin filament by spin level. The intensity change of 143a and 72a could offer information of the mass projection of population of myosin heads along the :filament axis. The slope of intensity profile of the mass projection of 143a and reflection of IASL is appeared and that of MSL is appeared sharply. The decrease of 215a reflection intensity is appeared the periodical characteristic of 143a reflection by spin label. The raise of MSL actin reflection at 51a and 59a in the actin reflection change refers that the shifted myosin head binds a certain actin or changes an actin structure by spin label effect. Because iodo acetamide has a tendency to decease the actin reflection, actin dose not bind myosin head. From this result, we could conclude that LASL and MSL are spin labeled on SH of myosin head and disordered the helix arrangement of actin.
        4,000원
        64.
        2005.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The structure of a carbon monoxide sorption complex of dehydrated fully Ca2+-exchanged zeolite X, |Ca46(CO)27|[Si100Al92O384]-FAU, has been determined in the cubic space group Fd 3 at 21℃ (a = 24.970(4) ) by single-crystal X-ray diffraction techniques. The crystal was prepared by ion exchange in a flowing stream of 0.05 M aqueous Ca(NO3)2 for three days, followed by dehydration at 400℃ and 2×10-6 Torr for two days, and exposure to 100 Torr of zeolitically dry carbon monoxide gas at 21℃. The structure was determined in this atmosphere and was refined, using the 356 reflections for which Fo 〉 4Σ(Fo), to the final error indices R1 = 0.059 and wR2 = 0.087. In this structure, Ca2+ ions occupy three crystallographic sites. Sixteen Ca2+ ions fill the octahedral site I at the centers of hexagonal prisms (Ca-O = 2.415(7) a). The remaining 30 Ca2+ ions are found at two nonequivalent sites II (in the supercages) with occupancies of 3 and 27 ions. Each of these Ca2+ ions coordinates to three framework oxygens, either at 2.276(10) or 2.298(8) a, respectively. Twenty-seven carbon monoxide molecules have been sorbed per unit cell, three per supercage. Each coordinates to one of the latter 16 site-II Ca2+ ions: C-Ca = 2.72(8) a. The imprecisely determined N-C bond length, 1.26(14) a, differs insignificantly from that in carbon monoxide(g), 1.13 a.
        4,000원
        65.
        2004.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        On contraction of the muscles, marked changes in X-ray reflections are observed, suggesting that conformational changes of contractile molecules and the movement of myosin heads during muscle contraction. Time slice requires tension peak after the onset of stimulation and the height of tension peak depends on the number of twitch cycle. The muscles were stimulated by five successive stimuli at an interval of 80 ms started while the tension was still being exerted by the muscles. The intensity of I11, I10, 143a and 215a reflection measured with 5ms time resolution and is recorded in isometric tension. The peak height of I11 and 143a intensity is changed after the onset of a stimulation Ii, and the length of twitch is shortened by successive twitches in the case of stimulation Ti. On the other hand, the peak height of In and 215a intensity starts to decrease at the 1st twitch and remains constant at low peak height without appreciable recovery during the contraction term. In the case of successive twitch stimulation, the myosin heads of muscle are once moved from their resting position and never returned to their initial position.
        4,000원
        66.
        2004.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The capacity and long life of gel electrolyte batteries is connected with gas recombination producting PbO2 and Pb electrode. We prepared with sulfuric acid gel electrolyte to know gel characteristics per density to assemble valve regulated lead-acid (VRLA) batteries. We studied on actions of sulphuric acid gel electrolyte by measuring electrolyte dispersion using Brewster-angle microscope (BAM), charge-discharge cycle, and electrode structure using scanning election microscope (SEM). Sulphuric acid density 1.210 showed excellent gel dispersion in sol condition, electrode condition after fifty cycles in this study.
        4,000원
        68.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sodium azide (SA) is commonly used as propellant for inflating automatic safety bags and other chemical manufacturing purposes. The investigation of potentially thermal hazard of sodium azide and its mixture with polymers are very important because it can occur an expected traffic accident so we took a experiment s using different scanning calorimeter (DSC) in nitrogen atmosphere. The decomposition temperature were about 350~450℃. We could find not only exothermic reaction was remarkably decreased in mixture s of acrylonitrile-butadiene-styrene (ABS) and polyvinyl chloride (PVC), but also increasing mixed rate of ABS, polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA) decreased thermal decomposition heat.
        4,000원
        69.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The capacity and long life of gel electrolyte batteries is connected with gas recombination producting PbO2 and Pb electrode. We were prepared with phosphoric acid gel electrolyte to know gel characteristics per density to assemble VRLA batteries. We studied by measuring electrolyte dispersion using Brewster-angle microscope(BAM), charge-discharge cycle and electrode structure using scanning election microscope(SEM) per electrolyte density. As a results, phosphoric acid density 1.210 was excellent gel dispersion in sol condition, electrode condition after fifty cycles in this study.
        4,500원
        70.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        IASL(iodo acetamide spin label) and MSL(maleimide spin label) disordered the orderly helix arrangement of myosin in the rest state of spin level. Especially the effect of IASL was great. The muscle was isometrically tetanized with three trains of 3ms pulses every 50ms between 5℃ with 25℃. Equatorial reflection change inferred that myosin head was moved to the vicinity of actin filament by spin level. The intensity change of 143a and 72a could offer information of the mass projection of population of myosin head along the filament axis. The slope of intensity profile of the mass projection of 143a and reflection of IASL is appeared and that of MSL is appeared sharply. The decrease of 215a reflection intensity the periodical character of 143a reflection by spin label. The raise of MSL actin reflection at 51a and 59a in the actin reflection change refers that the shifted myosin head binds a certain actin or changes an actin structure by spin label effect. Because iodo acetamide has a tendency to decease the actin reflection, actin dose not bind myosin head. From this result, we can conclude that IASL and MSL are spin labeled on SH of myosin head and disordered the helix arrangement of actin.
        4,000원
        71.
        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
        72.
        2003.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The core-shell latex particles were prepared by sequential emulsion polymerization of alkyl methacrylate and styrene(ST) by using an water-soluble initiator(APS) after preparing monomer pre-emulsion in the presence of an anionic surfactant(SDBS). In organic/organic core-shell polymerization, the pre-emulsion method, which minimized required quantity of sulfactant, has been used to increase the conversion rate and the stability of core-shell latex particles as well as to reduce the formation of secondary particle that cause problems of soap-free emulsion during shell polymerization. We used several methods to observe the core-shell structure. The core-shell structure was studied by measuring pH change during hydrolysis by NaOH, glass transition temperature(Tg) by differential scanning calorimeter(DSC), morphology of latex by transmission electron microscope(TEM) and change of particle size and distribution by a particle analyzer.
        4,000원
        73.
        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
        74.
        2002.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We carried out this experiment to observe electrochemical properties for LB films of phospholipid(Dilauroyl-L-α-Phosphayidylcholine) and 4-octyl-4'-(5-carboxypentamethylene-oxy)azobenzene mixture by the cyclic voltammetry. LB films of 8A5H and 8A5H-DLPC(1:1, 2:1) were deposited by using the Langmuir-Blodgett method on the ITO glass. We determined electrochemical measurement by using cyclic voltammetry with a three-electrode system, An Ag/AgCl reference elect rode, a platinum wire counter electrode and LB film-coated ITO working electrode measured in 0.1, 0.5, and 1.0 mol/L NaClO4 solution. A measuring range was reduced from initial potential to -1350 mV, continuously oxidized to 1650 mV and measured to the initial point. The scan rate were 50, 100, 150 and 200 mV/s. As a result, LB films of 8A5H 8A5H-DLPC appeared irreversible process caused by only the oxidation current from the cyclic voltammogram.
        4,000원
        75.
        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
        76.
        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
        77.
        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
        78.
        2000.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cellulose tosylate(CT) was prepared by reaction of cellulose with p- toluenesulfonylchloride in DMAc/LiCl homogeneous system. In order to study a reversible photoisomerization of disperse red 1(DR-1) attached on natural polymer, cellulose tosylate containing DR-1(DR-1/CT adduct) was prepared at 110℃ in DMAc, and the changes of UV/Vis spectra of its solutions and thick film were investigated by alternate irradiation technique. Form the UV/Vis spectra of DR-1/CT adduct dissolved in cosolvents, such as DMAc, DMAc/THF, DMAc/benzene, and DMAc/chloroform and irradiated with 360 nm and 450 nm ligths, we found out changes of UV/Vis spectra were reversible in all solvents systems and we found out changes of UV/Vis spectra were reversible at thick film, also.
        4,000원
        79.
        2000.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We synthesized the p-nonyloxyazobenzene derivatives with functional structures and carried out this experiments to observe photoisomerization irradiated by alternate lights. We found that it was reversibly induced to cis-trans photoisomerization in several solvents. Spreading solutions for the LB films were prepared in chloroform(1.2×10-2 mmol). As a result, it is found that the absorption spectra of the LB monolayer films was induced to photoisomerization by alternative irradiation lights, temperatures and pH(HCL and NH3), respectively.
        4,000원
        80.
        2000.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have investgated UV-Vis absorbance to observe the photoisomerization using the mixture solutions in chloroform and LB monolayers mixed with DLPE and 8A5H containing azobenzene which showed reversible cis-trans photoisomerization irradiated by alternate lights. We have found that the absorbance spectrums of the mixture solutions and LB monolayers were reversibly induced to cis-trans photoisomerization irradiated by alternate lights. In addition, the absorbance of both solution and LB monolayer mixed with 8A5H and DLPE were reversibly by alternate temperatures. As a results, the 1:1(by volume) mixture ratio of 8A5H and DLPE was more flexible and reversible cis-trans photoisomerization than the others.
        4,000원
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