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문철웅,정종훈,박천국,이승일,배학연,장경식,김만우,정춘해,홍순표,이병래,김호중 朝鮮大學校 附設 醫學硏究所 1993 The Medical Journal of Chosun University Vol.18 No.1
Renal ischemia is one of the most common causes of acute renal failure. Four factors related to the pathogenesis of acute renal failure are vasoconstriction, decreased glomerular filtration rate, tubular back leak of filtrate, and intratubular obstruction. The cellular response to renal ischemic insults include decreased content of adenosine trihosphate, lipid peroxidation induced membrane degradation, alteration in cellular pH, and calcium or phospholipase induced mitochondrial dysfunction. Much attention has been given to the role of increased cellular calcium as a pathogenetic contributor to cell injury during ischemia. Author studied the protective effects of calcium antagonists on cellular injury during renal ischemia in rat. To investigate the protective role of these agents, author measured the amount of malondialdehyde(MDA) and the enzyme activities of free radical scarvengers-superoxide dismutase(SOD), catalase and glutathione peroxidase from non-pretreated group and calcium antagonists pretreated groups in control, ischemia and reflow subgroups. The results were summerized as follows: 1) The amount of MDA in non-pretreated group was higher in the reflow compared with the control(<p<0.01). But, in all pretreated groups, there was no statistically difference in the amount of MDA. 2) The SOD activity in non-pretreated group was lower in both the ischemia and the reflow compared with the control (P<0.05). But, in both verapamil and trifluoperazine-pretreated groups, there was no statistically difference in the SOD activity. 3) Both catalase and glutathione peroxidase activities in non-pretreated group were lower in both the ischemia and the reflow compared with the control (P<0.05). But in all pretreated groups, there was no statically difference in both catalase and glutathione peroxidase activities. These results suggest that free radical mediated ischemic injury by renal artery clamp in rat can be protected by intraperitoneal pretreatment with calcium antagonists. As trifluoperazine has a protective effect in renal ischemia, the calcium activated calmodulin dependent enzyme may play a role in renal ischemic injury.
( Man-sig Lee ),( Gwang-ho Lee ),( Kwon-taek Lim ),( Gun-dae Lee ),( Seong-soo Hong ) 한국공업화학회 2002 한국공업화학회 연구논문 초록집 Vol.2002 No.0
Water-in-oil (W/O) microemulsions have previously been exploited to synthesize semiconductor nanoparticles. Microemulsions are well suited for this purpose because they are thermodynamically stable, optically clear solutions consisting of spatially defined aqueous nanodroplets. Through the design of surfactant that stabilize water droplets in near critical and supercritical CO<sub>2</sub>, water-in-CO<sub>2</sub> (W/C) microemulsions can be formed. CO<sub>2</sub> is nontoxic and nonflammable, thus offering many environmental and safety advantages over conventional oil based microemulsions. In this study, titania nanoparticles were prepared by controlled hydrolysis of titanium tetraisopropoxide in PFPE-NH<sub>4</sub> and PDMAEMA/Water-in-Carbon Dioxide Microemulsions. The physical properties, such as crystallite size and crystallinity according to Wo ratio have been investigated by TGA-DTA, FT-IR, XRD and TEM. In addition, the photocatalytic degradation of p-nitrophenol has been studied by using batch reactor in the presence of UV light in order to compare the photocatalytic activity of prepared nanosized titania. It is shown that the intensity and crystallite size of nanoparticles produced in Water-in-Carbon Dioxide Microemulsions were increases with increasing WO ratio. In the photocatalytic degradation of p-nitrophenol, the photocatalytic activity is mainly determined by the crystallite size of titania.
Lee, Man Sig,Lee, Gun-Dae,Hong, Seong-Soo 한국공업화학회 2003 Journal of Industrial and Engineering Chemistry Vol.9 No.4
Ti0₂ nanoparticles were prepared using hydrolysis of titanium tetraisopropoxide in W/O microemulsions consisting of water, nonionic Brij series surfactants, and cyclohexane. The properties of these particles were characterized by TEM, XRD, FT-IR, TGA and DTA. The photocatalytic degradation of p-nitrophenol has been studied in order to compare the photocatalytic activity of prepared nanosized titania. Ti0₂particles calcined at 500℃ have a stable anatase phase which has no organic surfactants. Above 300℃, the product completely transforms into the anatase phase and the rutile phase begins to appear at 600℃. The particles are shown to have a spherical shape and have an uniform size distribution but the shape becomes distorted with a decrease of hydrophilic group chain length according to rapid hydrolysis of water and titanium alkoxide. In addition, the crystallite size and crystallinity increase with a decrease of hydrophilic group chain length and an increase of calcinations temperature. The photocatalytic activity increases with an increase of hydrophilic group length and the titania calcined at 500℃ shows the highest activity on the photocatalytic degradation ofp-nitrophenol.
Catalytic Combustion of Benzene over Copper Oxide Supported on TiO_2 Prepared by Sol-Gel Method
Lee, Gwang-Ho,Lee, Man-Sig,Lee, Gun-Dae,Kim, Young-Ho,Hong, Seong-Soo 한국공업화학회 2002 Journal of Industrial and Engineering Chemistry Vol.8 No.6
Catalytic combustion of benzene was carried out using TiO_2 supported copper oxides. Ti0_2 catalysts were prepared by sol-gel method from the titanium isopropoxide. All catalysts were characterized by XRD, ESR and FT-Raman spectroscopy. The catalytic activity of CuO_x/TiO_2 catalysts according to preparation conditions was also examined. The major phase of all the prepared particles was anatase, while the rutile peak was observed above 700℃. From the ESR and FT-Raman results, the CuO dispersed on the TiO_2 surface acts as an active site of CuO_x/TiO_2 catalysts on the oxidative decomposition of benzene. The catalytic activity was shown almost similar activity on benzene conversion regardless of R ratio. In addition, the CuO_x supported on TiO_2 calcined at 400℃ showed the highest activity and the conversion reached almost 100% at 270℃. The catalytic activity gradually increased with an increase of Cu loading on TiO_2. When Cu loading reached 5.5 wt.%, the total conversion temperature was lowered to 300℃.
Lee, Man Sig,Lee, Gun-Dae,Hong, Seong-Soo 한국공업화학회 2003 Journal of Industrial and Engineering Chemistry Vol.9 No.5
Nanosized pure Ti0₂ particles were prepared by hydrolysis of TTIP in the sodium bis ( 2 -ethylhexyl) sulfosuccinate (AOT) reverse micelles. TiO₂/SiO₂ nanoparticles were also prepared from TEOS as a silicon source and TTIP as a titanium source for comparison. Properties of these particles were characterized by TEM, XRD, FT-IR, BET, TGA and DTA. From XRD data, no significant rutile phase was observed even though the TiO₂/Si0₂ particles were calcined at 800℃. The presence of amorphous silica in TiO₂/SiO₂particle enhanced the thennal stability of Ti02 particle and resulted in the suppression of the phase transition from anatase to rutile. The crystallite size of prepared particles decreased and the surface area increased monotonically with an increase of the silica content. From FT-IR analysis, the band for Ti-0-Si vibration was observed and the band for Si-0-Si vibration increased with an increase of the silica content. The micrographs of TEM show that the TiO₂/Si0₂ nanoparticles have a spherical morphology with a narrow size distribution. In addition, TiO₂/SiO₂ particles have higher photocatalytic activity than pure Ti0₂ and the Ti0₂/Si0₂(90/10) particles show the highest activity on the photocatalytic decomposition ofp-nitrophenol.
이만식(Man Sig Lee),정충택(Chung-Taeg Cheong),이광호(Gwang-Ho Lee),김준호(Jun-Ho kim),이근대(Gun-Dae Lee),홍성수(Seong-Soo Hong) 한국표면공학회 2002 한국표면공학회지 Vol.36 No.1
Zinc phosphating for cold forming of steel was studied with emphasis on decreasing phosphating temperature. To lower phosphating temperature, some techniques, such as adding Cu ion into bath, using activator in the form of pre-dip, and aeration in bath, instead of using conventional accelerator, namely oxidizing agent, have been tried. It was revealed that phosphating, leading to coatings of improved uniformity and fine crystal size, can be carried out using above techniques at lower temperature (55℃) compared to conventional phosphating temperature (80~90℃). Under present condition, it was seen that optimum concentrations of Cu ion in phosphating bath and activator in pre-dip are 0.015% (w/w) and 2.0 g/l, respectively. The coating weight was within the range of 15~20 g/㎡. When lubricant was applied into phosphating coatings, the amount of lubricating component (total soap) was found to be 6~10 g/㎡ and the lubricated panel revealed excellent lubricating properties.