• The Korean Journal of Ecology
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• 제27권2호
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• pp.107-114
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• 2004

Tomato (Lycopersicon esculentum) seedlings exposed to various concentrations of $CdC1_2$ (0∼100 $\mu$M) in the nutrient solution for up to 9 days were analyzed with the seedling growth, $H_2O_2$ production, glutathione levels and activity changes of enzymes related to $H_2O_2$ removal. The growth of seedlings was inhibited with over 50 $\mu$M Cd, whereas the levels of $H_2O_2$ and glutathione were enhanced with Cd exposure level and time. Meanwhile, Cd exposure increased the activities of catalase (CAT) and glutathione reductase (GR) but decreased the activities of dehydroascorbate acid reductase (DHAR) and ascorbate peroxidase (APX) in both leaves and roots. These results suggest that the altered activities of antioxidant enzymes particularly involved in the $H_2O_2$ removal and the subsequent $H_2O$$_2$ accumulation could induce the Cd-induced phytotoxicity.

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.77-80
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• 2007

As neurofilament proteins are major cytoskeletal components of neuron, abnormality of neurofilament is proposed in brain with neurodegenerative disorders such as Parkinson's disease (PD). Since oxidative stress might play a critical role in altering normal brain proteins, we investigated the oxidative modification of neurofilament-L (NF-L) induced by the reaction of cytochrome c with H2O2. When NF-L was incubated with cytochrome c and H2O2, the protein aggregation was increased in cytochrome c and H2O2 concentrationsdependent manner. Radical scavengers, azide, formate and N-acetyl cysteine, prevented the aggregation of NFL induced by the cytochrome c/H2O2 system. The formations of carbonyl group and dityrosine were obtained in cytochrome c/H2O2-mediated NF-L aggregates. Iron specific chelator, desferoxamine, prevented the cytochrome c/H2O2 system-mediated NF-L aggregation. These results suggest that the cytochrome c/H2O2 system may be related to abnormal aggregation of NF-L which may be involved in the pathogenesis of PD and related disorders.

• 공업화학
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• 제17권3호
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• pp.274-279
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• 2006

해중합 촉매인 zinc acetate ($C_{4}H_{6}O_{4}Zn{\cdot}2H_{2}O{\cdot}0.2\;mol$)와 lithuium hydroxide $H_{2}O$ ($LiOH{\cdot}H_{2}O{\cdot}0.14\;mol$)를 용매인 ethyl alcohol (99.9%)에 용해시킨 후 분산제인 hydroxypropyl cellulose (HPC)를 첨가하여 균일하게 분산된 ZnO (산화아연) 콜로이드 용액을 졸-겔법을 이용하여 합성하였다. ZnO 입자들의 크기와 모양은 분산제인 HPC에 의해 결정되었다. 또한 나노 크기의 ZnO 입자들은 zinc-2-ethylhexagonate를 기초로 한 침천법을 이용하여 얻었다. 이렇게 얻어진 ZnO 분말을 DLS, XRD, FE-SEM, 그리고 UV-Vis를 통하여 특성 분석을 하였다. 그 결과, 산화아연 분말은 자기조립 반응으로 균일하고 육방정계 모양의 구조를 가지는 것을 볼 수 있었다. 또 평균 입자 크기는 거의 40 nm이고 균일하게 분산되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.359-359
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• 2011

This study reports the H2S gas sensing properties of CuO / ZnO nano-hetero structure bundle and the investigation of gas sensing mechanism. The 1-Dimensional ZnO nano-structure was synthesized by hydrothermal method and CuO / ZnO nano-heterostructures were prepared by photo chemical reaction. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectra confirmed a well-crystalline ZnO of hexagonal structure. In order to improve the H2S gas sensing properties, simple type of gas sensor was fabricated with ZnO nano-heterostructures, which were prepared by photo-chemical deposition of CuO on the ZnO nanorods bundle. The furnace type gas sensing system was used to characterize sensing properties with diluted H2S gas (50 ppm) balanced air at various operating temperature up to 500$^{\circ}C$. The H2S gas response of ZnO nanorods bundle sensor increased with increasing temperature, which is thought to be due to chemical reaction of nanorods with gas molecules. Through analysis of X-ray photoelectron spectroscopy (XPS), the sensing mechanism of ZnO nanorods bundle sensor was explained by well-known surface reaction between ZnO surface atoms and hydrogen sulfide. However at high sensing temperature, chemical conversion of ZnO nanorods becomes a dominant sensing mechanism in current system. Photo-chemically fabricated CuO/ZnO heteronanostructures show higher gas response and higher current level than ZnO nanorods bundle. The gas sensing mechanism of the heteronanostructure can be explained by the chemical conversion of sensing material through the reaction with H2S gas.

• 대한약리학회지
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• 제20권1호
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• pp.1-11
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• 1984

인체 백혈구에서 추출한 myeloperoxidase(MPO)에 의한 NADH산화 및 methional에서의 ethylene 생성을 관찰하여 cell-free MPO/$H_2O_2/Cl^-$ system에서 관여하는 oxygen metabolites가 무엇인지를 규명하기 위하여 본 실험을 수행하였다. 1) NADH는 MPO/$H_2O_2/Cl^-$에 의하여 산화됨을 확인하였다. 즉 MPO, $H_2O_2$ 및 $Cl^-$가 존재하는 medium에서 NADH의 산화는 azide와 catalase에 의하여, 그리고 medium에서 $Cl^-$를 제거하였을 때 완전히 제거되었다. 2) 이와같은 MPO/$H_2O_2/Cl^-$에 의한 NADH산화는 $^1O_2$ 제거물질인 1,4-diazabicyclo(2,2,2) octane(DABCO)에 의하여 완전히 억제 되었으나 $OH{\cdot}$의 제거물질인 mannitol, benzoate, formate 및 methanol에 의해서는 영향을 받지 아니하였다. 3) 또한 methinal을 MPO/$H_2O_2/Cl^-$으로 처리하였을 때는 ethylene이 전혀 검출되지 아니하였으나 기타 $OH{\cdot}$을 생성할 것으로 알려진 산화계인 xanthine/xanthine oxidase 및 $Ca^{++}-H_2O_2$에 의해서는 현저한 ethylene생성을 관찰하였다. 이상의 결과는 Cell-free MPO/$H_2O_2/Cl^-$ 산화계에서는 $^1O_2$이 산화반응에 관여하는 주된 산소 대사물이며 $OH{\cdot}$은 생성되지 아니함을 알 수 있었다.

• 산업진흥연구
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• 제3권2호
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• pp.1-8
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• 2018

본 연구에서는 탄화수소 개질을 위한 예비 개질기에서 에탄의 반응 메커니즘과 이에 적합한 반응속도식에 대한 연구를 수행하였다. 반응 mechanism 분석을 통해 ethane의 개질 반응 중 (CO2+H2,C2H6+H2,C2H6+H2O)3개의 반응이 진행되는 것을 확인할 수 있었으며, 각각의 반응 속도 (CO2+H2($r=3.42{\times}10-5molgcat.-1\;s-1$), C2H6+H2($r=3.18{\times}10-5mol\;gcat.-1s-1$), C2H6+H2O($r=1.84{\times}10-5mol\;gcat.-1s-1$)) 를 구하였다. 이를 통해 C2H6+H2O반응이 rate determining step (RDS)임을 확인하고, Langmuir-Hinshelwood model (L-H model)을 통해 이 반응의 반응식을 r=kS*(KAKBPC2H6PH2O)/(1+KAPC2H6+KBPH2O)2 (KA=2.052,KB=6.384,$kS=0.189{\times}10-2$)로 나타낼 수 있었다. 이렇게 얻어진 반응식은 반응 메커니즘을 고려하지 않고 유도된 power rate law와 비교하였으며, power rate law는 좁은 농도 변화 영역 (ethane 약 2.5-4%, water 약 60-75%)에서는 비교적 유사한 fitting이 이루어졌지만, 넓은 농도 변화영역에서는 반응 mechanism을 토대로 얻은 L-H model 반응식이 실험값과 더 유사한 값을 보이는 것을 확인하였다.

• 대한수의학회지
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• 제36권2호
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• pp.371-378
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• 1996

Three and 2 strains of E coli O157 were isolated from fecal materials of cattle (390) and pigs (420) in Korea, respectively. One strain of O157:H7 isolated from cattle and 2 strains of O157:H7 isolated from pigs were identified as verotoxin-1 (VT-1) produing strains and 2 strains (O157:H7 and O157:H-) isolated from cattle were identified as verotoxin-2 (VT-2) producing strains by neutralization test on HeLa and Vero cells. Culture supernatants of the isolates were cytotoxic to HeLa and Vero cells. The levels of cytotoxin produced by isolates were $10^2{\sim}10^4$ cytotoxic dose($CD_{50}$)/ml. Also, VT-2-converting bacteriophage was isolated from KSC109 strain which had been isolated from cattle. Molecular weight of the phage DNA was determined as approximately 45 Kb in 0.8% agarose gel electrophoresis, and morphology of the phage stained with phosphotungstic acid was observed by transmissible electron microscopy.

• Journal of Microbiology and Biotechnology
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• 제30권6호
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• pp.830-838
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• 2020

The histone-like nucleoid structuring protein (H-NS) is an abundant global regulator of environmentally controlled gene expression. Herein, we demonstrate that H-NS represses the expression of LeuO, the master regulator of the cyclic(Phe-Pro)-dependent signaling pathway, by directly binding to the upstream region of the gene. H-NS binds to a long stretched region (more than 160-bp long), which overlaps with binding sites for ToxR and LeuO. A high quantity of H-NS outcompetes ToxR for binding to the cis-acting element of leuO. However, our footprinting analyses suggests that the binding of H-NS is relatively weaker than LeuO or ToxR at the same molarity. Considering that the DNA nucleotide sequences of the upstream regions of leuO genes are highly conserved among various Vibrio, such patterns as those found in V. vulnificus would be a common feature in the regulation of leuO gene expression in Vibrionaceae. Taken together, these results suggest that, in species belonging to Vibrionaceae, H-NS regulates the expression of leuO as a basal stopper when cFP-ToxR mediated signaling is absent.

• 한국대기환경학회지
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• 제22권3호
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• pp.297-307
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• 2006

During January $2002{\sim}April\;2004$, hydrogen peroxide ($H_{2}O_{2}$) measurements were performed at the campus of Korea University, which is located in the northeastern part of Seoul. Gas phase hydroperoxide was collected in aqueous solution and separated by HPLC. Concentrations were determined by fluorescence using postcolumn enzyme derivatization. This measurement system was improved to be run automatically from sample collection at every 10 minutes through chemical analysis for data collection. Detection limits of $H_{2}O_{2}$ is $10{\sim}17\;pptv$, and the overall uncertainty of the measurements is better than 8%. Two-year measurements of $H_{2}O_{2}$ show typical seasonal variations. Concentrations of $H_{2}O_{2}$ were higher during $June{\sim}October$ and lower during $January{\sim}February$. Maximum concentration of 1-hour averaged $H_{2}O_{2}$ was 6.5 ppbv, which was observed in August and September. In general $H_{2}O_{2}$ concentrations were well correlated with $O_{3}$ concentrations and largely affected by meteorological factors such as temperature and wind direction.

• 대한화학회지
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• 제34권6호
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• pp.534-538
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• 1990

H$_2$O을 용매로 하여 헤테로고리 염기인 이소퀴놀린과 CrO$_3$를 반응시켜 Cr(Ⅵ)화합물인 [$C_9H_7$NH]$_2Cr_2O_7$을 얻었다. 이 화합물은 비흡수성이면서 물에 잘 녹았다. 그리고 원소분석, 적외선 분광법으로 이 화합물의 구조가 [$C_9H_7$NH]$_2Cr_2O_7$임을 확인하였다. 또한, 이 화합물이 여러 가지 알코올을 알데히드나 케톤으로 전환시킬 수 있는 산화제로 작용하는가를 알아보기 위하여 알릴, 일차, 이차 알코올을 각각 산화반응에 이용한 결과 알코올들에 대해 효율적인 산화제로 작용하였다.