• 미생물학회지
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• 제38권4호
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• pp.209-209
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• 2002

Mycobacterium sp. strain JCl DSM 3803 grown in methanol showed no methanol dehydrogenase or oxidase activities found in mast methylotrophic bacteria and yeasts, respectively. Even though the methanol-grown cells exhibited a little methanol-dependent oxidation by cytochrome c-dependent methanol dehydrogenase and alcohol dehydrogenase, they were not the key enzymes responsible for the methanol oxidation of the cells, in that the cells contained no c-type cytochrome and the methanol oxidizing activity from the partially purified alcohol dehydrogenase was too low, respectively. In substrate switching experiments, we found that only a catalase-peroxidase among the three types of catalase found in glucose-grown cells was highly expressed, in the methanol-grown cells and that its activity was relatively high during the exponential growth phase in Mycobacterium sp. JCl. Therefore, we propose that catalase-peroxidase is an essential enzyme responsible for the methanol metabolism directly Of indirectly in Mycobacterium sp. JCl.

• Bulletin of the Korean Chemical Society
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• 제17권4호
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• pp.324-330
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• 1996

We examined the formal oxidation states of Pb and Cu in the Pb2CuO4 slab of Pb2Sr2ACu3O8(A=Y1-xCaxor Nd1-xSrx) and their possible changes by oxygen incorporation in the Cu layer of the slab by performing tight-binding band electronic structure calculations on the Pb2CuO4+δ slab. Our results show that the most likely oxidation state of Pb is +2 and that of Cu is +1 for the Pb2CuO4 slab prior to oxidation. With small δ values, the oxygen incorporation occurs by the formation of such chain fragments as in YBa2Cu3O7-y along the a+b axis. The four-coordinate Cu atoms in the chain fragments are in the +3 oxidation states. For values of δ larger than 0.5, however, an additional oxygen (Oad) goes to the site along the b axis to form short Pb-Oad distances oxidizing Pb2+ to Pb4+. This change in the Pb oxidation state leads to the suppression of superconductivity due to the decrease of holes in the CuO2 layer.

• Archives of Pharmacal Research
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• 제25권2호
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• pp.184-191
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• 2002

We investigated the role of vitamin C or rutin on neuropathy and lung damage of diabetic mellitus(DM) rats. Norepinephrine content was significantly decreased in sciatic nerves of DM rats compared with non-DM controls but vitamin C had no effect on decreases of norepinephrine. 2,4-dinitrophenylhydrazine (DNPH) incorporation, which is biomarker of protein oxidation, was increased in sciatic nerve of DM rats as compared with normal control. However, vitamin C had no effects on increases of DNPH incorporation . We measured the content of conjugated dienes (CD) as a biomarker of lipid oxidation in sciatic nerve. CD was increased in DM as compared with normal control, Vitamin C or rutin had no effects on increases of CD. However, Rutin plus vitamin C significantly decreased the content of CD as compared with CIM rats. In lung of DM rats, DNPH incorporation or CD was increased as compared with normal control. Vitamin C or Rutin had no effects on increases of CD However, Rutin plus vitamin C significantly decreased the content of DNPH incorporation or CD in lung tissue. Vitamin C caused marked pathological changes such as the increases of parenchyma and the thickening of alveolar septa in the lung of DM. Rutin had protective effects on the pathological changes in the lung of DM rats. In conclusion, Vitamin C had no effects on oxidative parameter, such as DNPH incorporation or CD, and on the decreases of norepinephrine content in DM rats. Vitamin C caused the marked pathological changes in the lung of DM rats but rutin had protective efforts against the pathological changes.

• 한국세라믹학회지
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• 제22권6호
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• pp.5-8
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• 1985

Graphite has been oxidized to graphite hydrogen sulfate in concentrated $H_2SO_4$. Anodic oxidation and chemical oxidation of graphite in $H_2SO_4$ generally leads to the formation of intercalation compounds of the ionic salt type through incorporation of $H_2SO_4^-$ions and $H_2SO_4$ molecules into the graphite. Several other reactions also accur at various points of the charging cycle. But there is no satisfactory kinetics and mechanism of intercalationin graphite. We have studied them with anodic oxidation and chemical oxidation. We found six distinct phenomena between 2nd stage and 1st stage in chemical oxidation. We examined them in detail by the following in the measurements electrical oxidation. X-ray diffractions UV-Vis spectroscopy density measurements. We could obtained a equation for kinetic according to the reaction rate from this results and mechanism of intercalation between 2nd stage and 1st stage with hydrogen sulfate in graphite. Three thesis were written for the mechanism of intercalation compounds in graphite with hydrogen sulfate ; first thesis is anodic oxidation second thesis is chemical oxidation and definition of transit phase between 2nd etc the third thesis is the kinetic mechanism of intercalation compounds in graphite with Hydrogen sulfate. This thesis is the first paper among three thesis as anodic oxidation.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.690-693
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• 2003

An Si substrate (100) was oxidized at $400^{\circ}C$ in inductively coupled oxygen plasma. Interstitial oxygen was found in the Si substrate at the initial stage of oxidation by IR measurements. An x-ray rocking curve of Si substrates showed a lower peak intensity due to lattice distortion by the interstitial oxygen. The refractive index of thin oxides, below which interstitial oxygen existed in the Si substrate, was smaller than the refractive index of thick oxides, below which no interstitial oxygen existed. The interstitial oxygen was found by plasma oxidation using $O_{2}$ gas and $N_{2}O$ gas. The inductively coupled plasma oxidation using $N_{2}O$ gas was performed by atomic oxygen, not by molecular oxygen, indicating that atomic oxygen in plasma is responsible for the incorporation of interstitial oxygen.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
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• pp.7-11
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• 2012

Plasma electrolytic oxidation of magnesium alloys is a well known technique to produce corrosion and wear resistant coatings. The addition of particles to the electrolyte provides a possibility to produce coatings with an increasing range of composition by in-situ incorporation of those particles into the coating. An extensive literature review has revealed that the mode of incorporation depends mainly on the melting point of the used particles and the energy provided by the discharges of the PEO process. The spectrum ranges from inert to partly reactive incorporation, but a complete reactive incorporation and a formation of a new single phase coating was not observed so far. Thus a new approach in PEO processing is introduced using specific particles as a kind of sintering additive, changing not only the composition but lowering the melting temperature and increase the liquid phase fraction during the discharges, resulting in a new amorphous coating.

• Korean Chemical Engineering Research
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• 제49권1호
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• pp.1-9
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• 2011

티타니아, 바나디아, 지르코니아, 세리아를 고정한 실리카에 백금을 담지한 후 과산화수소로 처리하여 제조한 백금 촉매에서 산화물 고정과 과산화수소 처리가 백금의 분산 상태 및 일산화탄소 산화반응에서 이들의 촉매 활성에 미치는 영향을 조사하였다. 산화물을 고정하고 과산화수소로 처리하면 실리카에도 백금이 잘 분산될 수 있음을 XRD, TEM, EXAFS, XPS, 일산화탄소 화학흡착 방법으로 검증하였다. 그러나 일산화탄소의 흡착성질과 일산화탄소 산화반응에서 촉매 활성은 고정한 산화물 종류에 따라 상당히 달랐다. 티타니아, 지르코니아, 세리아를 실리카에 고정하고 과산화수소로 처리하여 제조한 백금 촉매에서는 백금의 분산도가 높아져서 일산화탄소 산화반응에서 활성이 증진되었다. Pt-O-Zr 결합이 생성되어 백금의 분산도가 크게 향상된 지르코니아 고정 백금 촉매에서 산화물 고정과 과산화수소 처리로 인한 활성 증진 효과가 가장 컸다.

• Corrosion Science and Technology
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• 제15권3호
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• pp.129-134
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• 2016

The effects of Ti on the high temperature oxidation of Ni-based superalloys were investigated by cyclic oxidation at $850^{\circ}C$ and $1000^{\circ}C$. The oxide scale formed at $850^{\circ}C$ consists of $Cr_2O_3$, $Al_2O_3$, and $NiCr_2O_4$ layers, while a continuous $Al_2O_3$ layer was formed at $1000^{\circ}C$. The oxidation rate of the alloy with higher Ti content was higher than the alloy with less Ti content at $850^{\circ}C$, possibly due to the increase in the metal vacancy concentration in the $Cr_2O_3$ layer involved by incorporation of $Ti^{4+}$. However, Ti improved the oxidation resistance of the superalloy at $1000^{\circ}C$ by reducing oxygen vacancy concentration in $Al_2O_3$ layer.

• Applied Science and Convergence Technology
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• 제26권5호
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• pp.133-138
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• 2017

We investigated the interface defect engineering and reaction mechanism of reduced transition layer and nitride layer in the active plasma process on 4H-SiC by the plasma reaction with the rapid processing time at the room temperature. Through the combination of experiment and theoretical studies, we clearly observed that advanced active plasma process on 4H-SiC of oxidation and nitridation have improved electrical properties by the stable bond structure and decrease of the interfacial defects. In the plasma oxidation system, we showed that plasma oxide on SiC has enhanced electrical characteristics than the thermally oxidation and suppressed generation of the interface trap density. The decrease of the defect states in transition layer and stress induced leakage current (SILC) clearly showed that plasma process enhances quality of $SiO_2$ by the reduction of transition layer due to the controlled interstitial C atoms. And in another processes, the Plasma Nitridation (PN) system, we investigated the modification in bond structure in the nitride SiC surface by the rapid PN process. We observed that converted N reacted through spontaneous incorporation the SiC sub-surface, resulting in N atoms converted to C-site by the low bond energy. In particular, electrical properties exhibited that the generated trap states was suppressed with the nitrided layer. The results of active plasma oxidation and nitridation system suggest plasma processes on SiC of rapid and low temperature process, compare with the traditional gas annealing process with high temperature and long process time.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2405-2408
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• 2007

Oxidation of alkylaromatics including toluene and p-methoxytoluene has been carried out over alkali metal (AM)-containing catalysts such as AM-V/TiO2 and AM-VSb/Al2O3 in vapor-phase using oxygen as an oxidant. The selectivity for partial oxidations increases with incorporation of an alkali metal or with increasing the basicity of alkali metals (from Na to Cs), irrespective of the supports or reactants. However, the conversion is nearly constant or slightly decreasing with the addition of alkali metals in the catalyst. The increased selectivity may be related with the decreased acidity even though more detailed work is necessary to understand the effect of alkali metals in the oxidation. The AM-VSb/Al2O3 may be suggested as a potential selective catalyst for vapor-phase oxidations.