• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.1982-1991
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• 2018

Ethanol accumulation inhibited the growth of Saccharomyces cerevisiae during wine fermentation. Autophagy and the release of reactive oxygen species (ROS) were also induced under ethanol stress. However, the relation between autophagy and ethanol stress was still unclear. In this study, expression of the autophagy genes ATG1 and ATG8 and the production of ROS under ethanol treatment in yeast were measured. The results showed that ethanol stress very significantly induced expression of the ATG1 and ATG8 genes and the production of hydrogen peroxide ($H_2O_2$) and superoxide anion (${O_2}^{{\cdot}_-}$). Moreover, the atg1 and atg8 mutants aggregated more $H_2O_2$ and ${O_2}^{{\cdot}_-}$ than the wild-type yeast. In addition, inhibitors of the ROS scavenging enzyme induced expression of the ATG1 and ATG8 genes by increasing the levels of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. In contrast, glutathione (GSH) and N-acetylcystine (NAC) decreased ATG1 and ATG8 expression by reducing $H_2O_2$ and ${O_2}^{{\cdot}_-}$ production. Rapamycin and 3-methyladenine also caused an obvious change in autophagy levels and simultaneously altered the release of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. Finally, inhibitors of the mitochondrial electron transport chain (mtETC) increased the production of $H_2O_2$ and ${O_2}^{{\cdot}_-}$ and also promoted expression levels of the ATG1 and ATG8 genes. In conclusion, ethanol stress induced autophagy which was regulated by $H_2O_2$ and ${O_2}^{{\cdot}_-}$ derived from mtETC, and in turn, the autophagy contributed to the elimination $H_2O_2$ and ${O_2}^{{\cdot}_-}$.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.11a
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• pp.192-194
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• 2005

O$_3$/H$_2$O$_2$ 고급산화공정에서 1,4-D의 제거는 반응시간에 따라 완만하게 감소하였으나, O$_3$/catalyst 고급산화공정에서는 전체 제거량의 약 50${\sim}$75%가 반응 초기 5분 내에 제거되어 O$_3$/H$_2$O$_2$ 공정에 비해 초기 반응속도가 현저히 빠른 것을 알 수 있었다. O$_3$/H$_2$O$_2$ 고급산화공정은 ${\Delta}$TOC/${\Delta}$ThOC의 비는 0.09${\sim}$0.40으로 나타났으며, O$_3$/catalyst 고급산화공정에서는 ${\Delta}$TOC/${\Delta}$ThOC의 비가 0.68${\sim}$0.98로 나타나 O$_3$/catalyst 고급산화공정이 O$_3$/H$_2$O$_2$ 고급산화공정에 비해 유기물의 산화력이 우수한 것으로 확인되었다.

• Journal of the Korean Chemical Society
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• v.31 no.2
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• pp.178-183
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• 1987

The kinetics of the reaction of $[Mo_3O_4(H_2O)_9]^{4+}$ with $VO_2^+$have been studied at $25^{\circ}C$ by spectrophotometric method. With$VO_2^+$ in excess, the $[Mo_3O_4(H_2O)_9]^{4+}$ reaction can be expressed as $Mo^{IV}_3+6V^V{\rightleftarrows}3Mo^{IV}+6V^IV}$. Observed rate constants for the reaction are dependent on [$H^+$] and [$VO_2^+$]. Mechanism for the redox of $[Mo_3O_4(H_2O)_9]^{4+}$and $VO_2^+$ is proposed and discussed.

• Journal of Chest Surgery
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• v.33 no.12
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• pp.935-940
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• 2000

배경: 폐혈관 손상에 관한 기전은 여러 보고에도 불구하고 자세히 밝혀지지는 않았다. 최근 산화성 스트레스 질환에 관여하는 과산화 수소($H_2O$$_2$) 등의 활성 산소족(reactive oxygen species)은 세포손상과 세포자사(apoptosis)에 중요한 역할을 한다고 알려져 있다. 본 연구에서는 $H_2O$$_2$에 의하여 유발된 산화성 스트레스가, 폐혈관 손상 기전의 하나로 추측되고 있는 세포자사를 야기하는지를 연구하였다. 대상 및 방법: 소의 폐동맥에서 유래된 calf pupmonary artery endothelial cell line(CPAE)를 이용하였다. $H_2O$$_2$에 의한 세포 독성을 측정하기 위하여, 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide(MTT) assay를 시행하였다. $H_2O$$_2$에 의한 세포의 형태학적 변화는 도립 현미경으로 분석하였다. 세포자사를 확인하기 위하여 terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling(TUNEL) assay와 4,6-diamidino-2-phenylindole(DAPI) staining 방법 및 flow cytometry 분석를 시행하였다. 결과: $H_2O$$_2$에 의한 세포 생존율은, 대조군(100%)과 비교하여 3시간 실험군에서 10$\mu$M에서 약 70%, 50 $\mu$M에서 약 33%, 100 $\mu$M에서 약 26%, 500 $\mu$M에서 약 28%이였다. $H_2O$$_2$투여시 세포돌기 감소, 세포 축소, 세포질 응축과 불규칙한 형태 등의 세포자사에 나타나는 형태학적 변화를 나타내었다. TUNEL assay와 DAPI staining에서도 세포자사에 특징적으로 나타나는 핵응축과 핵분절 등의 소견을 나타내었다. Flow cytometry 분석 시에도 $H_2O$$_2$투여시 sub G$_1$분절의 증가와 G$_1$분절의 감소 등의 세포자사 양상이 확인되었다. 결론: 형태학적 분석과 생화학적 분석을 통하여, $H_2O$$_2$는 CPAE에서 세포자사를 야기함을 확인하였다. 이러한 결과는 폐혈관 손상의 기전에 $H_2O$$_2$에 의한 세포자사가 부분적으로 관여할 가능성을 제시한다.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.4
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• pp.107-117
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• 2005

The objective of this study was to investigate the proper operation conditions of fenton oxidation such as initial pH, $H_2O_2/Fe^{2+}$ ratio, $H_2O_2/Fe^{2+}$ dosage amount, and neutralizing agent for pretreatment of the livestock wastewater. Fenton oxidation reagents were reacted with the livestock wastewater for 2 hours at 120 rpm and the settling was performed for 2 hours using jar-tester apparatus under the different experimental conditions. And then the supernatant was sampled and measured for the residual $H_2O_2$, $COD_{Cr}$, and SS. The results are as follows; optimum initial pH=4, optimum $H_2O_2/Fe^{2+}$ ratio=10:1, optimum $H_2O_2/Fe^{2+}$ dosage amount=5,000/500 mg/L and $Ca(OH)_2$ as proper neutralizing agent. The removal efficiency of $COD_{Cr}$ and SS were 43% and 84% under those optimal fenton oxidation conditions.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.410-416
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• 2006

For highly efficient operation of a Bunsen process section in an iodine-sulfur thermochemical hydrogen production cycle using nuclear heat, the process characteristics of $H_2SO_4-HI-H_2-O-I_2$ mixture system for separating into two liquid phases ($H_2SO_4$-rich phase and $HI_x$-rich phase) and the distribution of $H_2O$ to each phase were investigated.The experiments for process variables were carried out in the temperature range, from 298 to 353 K, and in the $H_2SO_4/HI/H_2O/I_2$ molar ratio of 1/2/14~20/0.5~8.0. As the results, for the $SO_2-I_2-H_2O$ Bunsen reaction system, the ranges between the starting point and the saturation point for two liquid phases separation were determined by calculation. The best result for the minimization of impurities (HI and $I_2$ in $H_2SO_4$ phase and $H_2SO_4$ in $HI_x$ phase) in each phase was obtained in an optimum condition with the highest temperature of 353 K and the highest $I_2$ molar composition. In this condition, the $HI/H_2SO_4$ molar ratio in the $H_2SO_4$-rich phase and the $H_2SO_4/HI_x$ molar ratio in the $HI_x$-rich phase were 0.024 and 0.028, respectively. For the distribution of $H_2O$ to each phase, it is appeared that the affinity between $HI_x$ and $H_2O$ was more superior to that between $H_2SO_4$ and $H_2O$. The affinity between $HI_x$ and $H_2O$ was decreased with increasing temperature but increased with increasing $I_2$ molar composition.

• The Korean Journal of Pharmacology
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• v.20 no.1 s.34
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• pp.1-11
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• 1984

The present study was performed to determine oxygen metabolites involved in cell-free MPO/$H_2O_2/Cl^-$ system by observing the effects of their scavengers on NADH oxidation and ethylene production from methional by the action of MPO prepared from human leukocytes. It was clearly demonstrated that NADH was oxidized by the cell-free MPO/$H_2O_2/Cl^-$ system as evidenced by complete inhibition of the oxidation of the substrate in the presence of eiher azide or catalase, or by omitting $Cl^-$. The MPO-mediated oxidation of NADH was completely abolished by a $^1O_2$ quencher, DABCO but not by $OH{\cdot}$ scavengers, mannitol, benzoate, formate and methanol. In ethylene assay, no ethylene was detected from methional in the MPO/$H_2O_2/Cl^-$ system with evident production of the gas by xanthine-oxidase and $Cu^{++}-H_2O_2$ systems which are suggested to generate $OH{\cdot}$. From the results obtained, it is concluded that $^1O_2$ is a major mediator with exclusion of $OH{\cdot}$ involvement in the cell-free MPO-mediated oxidation.

• Journal of the Korean Ceramic Society
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• v.35 no.12
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• pp.1336-1336
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• 1998

A twt -step carbothermal reduction scheme has been employed for the synthesis of SiC whiskers in an Ar or a H2 atmosphere via vapor-solid two-stage and vapor-liquid-solid growth mechanism respectively. It has been shown that the whisker growth proceed through the following reaction mechanism in an Ar at-mosphere : SiO2(S)+C(s)-SiO(v)+CO(v) SiO(v)3CO(v)=SiC(s)whisker+2CO2(v) 2C(s)+2CO2(v)=4CO(v) the third reaction appears to be the rate-controlling reaction since the overall reaction rates are dominated by the carbon which is participated in this reaction. The whisker growth proceeded through the following reaction mechaism in a H2 atmosphere : SiO2(s)+C(s)=SiO(v)+CO(v) 2C(s)+4H2(v)=2CH4(v) SiO(v)+2CH4(v)=SiC(s)whisker+CO(v)+4H2(v) The first reaction appears to be the rate-controlling reaction since the overall reaction rates are enhanced byincreasing the SiO vapor generation rate.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.5
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• pp.669-678
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• 2009

The reduction of excess activated sludge from petrochemical plant was investigated by the electro fenton (E-Fenton) process using electrogenerated hydroxyl radicals which lead to mineralization of activated sludge to $CO_2$, water and inorganic ions. Factors affecting the disintegration efficiency of excess activated sludge in E-Fenton process were examined in terms of five criteria: pH, $H_2O_2/Fe^{2+}$ molar ratio, current density, initial MLSS (mixed liquid suspended solids) concentration, $H_2O_2$ feeding mode. TSS total suspended solid and $TCOD_{cr}$ reduction rate increased with the increasing $H_2O_2/Fe^{2+}$ molar ratio and current density until 42 and $6.7 mA/cm^2$, respectively but further increase of $H_2O_2/Fe^{2+}$ molar ratio and current density would reduce the reduction rate. On the other hand, as expected, increasing pH and initial MLSS concentration of activated sludge decreas TSS and $TCOD_{cr}$ reduction rate. The E-Fenton process was gradually increased during first 30 minutes and then linearly proceed till 120 minutes. The optimal E-Fenton condition showed TSS reduction rate of 62~63% and $TCOD_{cr}$ (total chemical oxygen demand) reduction rate of 55~56%. Molar ratio $H_2O_2/Fe^{2+} = 42$ was determined as optimal E-Fenton condition with initial $Fe^{2+}$ dose of 5.4 mM and current density of $6.7{\sim}13.3 mA/cm^2$, initial MLSS of 7,600 mg/L and pH 2 were chosen as the most efficient E-Fenton condition.

• Journal of the Korean Chemical Society
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• v.51 no.4
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• pp.339-345
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• 2007

Urea reacts with PtCl2, H2[PtCl6]·6H2O, H2[IrCl6] and Ni(CH3CO2)2 in aqueous solution at high temperature (60-80 °C) yielding [PtCl2(Urea)]·2H2O (1), (NH4)2[PtCl6] (2), (NH4)2[IrCl6]·H2O (3) and [Ni2(OH)2(NCO)2(H2O)2] (4) complexes, respectively. In complex 1, urea coordinates to Pt(II) as a neutral bidentate ligand via amido nitrogen atoms. In complexes 2, 3 and 4 it seems that the coordinated urea molecules decompose during the reaction at high temperature and a variety of reaction products are obtained. All complexes were isolated in moderate yields as dark green (1), yellow (2), pale brown (3) and faint green (4) precipitates, respectively. The reaction products were characterized by their microanalysis, IR, 1H and 13C NMR spectra as well as thermal analysis. General mechanisms describing the formation of these complexes were suggested.