• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.212-212
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• 2011

In addition to the catalysts' activity and selectivity, the deactivation of catalysts during use is of practical importance. It is crucial to understand the phenomena of the deactivation to predict the loss of activity during catalyst usage so that the high operational costs associated with catalyst replacement can be reduced. In this study, the activity of Ru catalysts, such as nanoparticles (3~6 nm) and polycrystalline thin film (50 nm), have been investigated under CO oxidation and oxidative/reductive reaction conditions at various temperatures with the ambient pressure X-Ray photoelectron spectroscopy (APXPS). With APXPS, the surface oxides on the catalyst are measured and monitored in-situ. It was found that the Ru film exhibited faster oxidation-and-reduction compared to that of nanoparticles showing mild oxidative-and-reductive characteristics. Additionally, the larger Ru nanoparticles showed a higher degree of oxide formation at all temperatures, suggesting a higher stability of the oxide. These observations are in agreement with the catalytic activity of Ru catalysts. The loss of activity of Ru films is correlated with bulk oxide formation, which is inactive in CO oxidation. The Ru nanoparticle, however, does not exhibit deactivation under similar conditions, suggesting that its surface is covered with a highly active ultrathin surface oxide. Since the active oxide is more stable as nanoparticles than as a film, the nanoparticles showed mild oxidative/reductive behavior, as confirmed by APXPS results. We believe these simultaneous observations of both the surface oxide of Ru catalysts and the reactivity in real time enable us to pinpoint the deactivation phenomena more precisely and help in designing more efficient and stable catalytic systems.

• 공업화학
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• 제5권4호
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• pp.580-587
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• 1994

고정층 상압 유통식 반응기에서 메탄의 전화율 10% 미만의 범위에서 $Na^+(50wt%)/MgO$ 촉매를 사용하여 반응온도 710, 730, 750, 770, $790^{\circ}C$에서 메탄과 산소의 분압을 변화시켜 가면서 메탄의 oxidative coupling반응을 수행하여 이산화탄소와 에탄의 생성속도를 구하고 curve fitting으로 속도식을 증명하였다. Langmuir-Hinshelwood, Rideal-Redox, Eley-Rideal형 반응 메카니즘 중에서 Langmuir-Hinshelwood형 반응 메카니즘이 실험 결과와 가장 잘 일치하였으며, $CH_3{\cdot}$의 생성에 관여하는 산소종은 촉매 표면의 $O_2{^-}$ 또는 $O_2{^{2-}}$으로 제시할 수 있었고, 이때의 활성화 에너지는 약 39.3kcal/mol이었다. 또한, curve fitting결과 $CO_x$을 생성하는 산소의 화학 양론계수 x는 약 1.5이었으며, 이로부터 $CH_3{\cdot}$의 일부가 표면산소에 의해서 산화반응을 거쳐 $CH_3O_2{\cdot}*$ 형성을 추측할 수 있었다.

• Animal Bioscience
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• 제36권7호
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• pp.1120-1129
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• 2023

Objective: This study aimed to determine the protective efficacy of Buddha's Temple (BT) extract against tert-butyl hydroperoxide (t-BHP)-induced oxidative stress in Gallus gallus chicken embryo fibroblast cell line (DF-1) and its effects on the cell lipid metabolism. Methods: In this experimental study, Gallus gallus DF-1 fibroblast cells were pretreated with BT 10^-7 for 24 hours, followed by their six-hour exposure to t-BHP (100 μM). Water-soluble tetrazolium salt-8 (WST-8) assays were performed, and the growth curve was computed. The intracellular gene expression changes caused by BT extract were confirmed through quantitative polymerase chain reaction (qPCR). Flow cytometry, oil red O staining experiment, and thin-layer chromatography were performed for the detection of intracellular metabolic mechanism changes. Results: The WST-8 assay results showed that the BT pretreatment of Gallus gallus DF-1 fibroblast cell increased their cell survival rate by 1.08%±0.04%, decreased the reactive oxygen species (ROS) level by 0.93%±0.12% even after exposure to oxidants, and stabilized mitochondrial activity by 1.37%±0.36%. In addition, qPCR results confirmed that the gene expression levels of tumor necrosis factor α (TNFα), TIR domain-containing adapter inducing IFN-beta (TICAM1), and glucose-regulated protein 78 (GRP78) were regulated, which contributed to cell stabilization. Thin-layer chromatography and oil red O analyses showed a clear decrease in the contents of lipid metabolites such as triacylglycerol and free fatty acids. Conclusion: In this study, we confirmed that the examined BT extract exerted selective protective effects on Gallus gallus DF-1 fibroblast cells against cell damage caused by t-BHP, which is a strong oxidative inducer. Furthermore, we established that this extract significantly reduced the intracellular ROS accumulation due to oxidative stress, which contributes to an increase in poultry production and higher incomes.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2023년도 임시총회 및 춘계학술대회
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• pp.54-54
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• 2023

Nypa fruticans Wurmb (N. fruticans) is a plant that belongs to Araceae and N. fruticans is mainly found in tropical mangrove systems. The parts (leaves, stems, and roots) of N. fruticans are traditionally used for asthma, sore throat, and liver disease. N. fruticans contains flavonoids and polyphenols, which are substances that have inhibitory effects on cancer and oxidant. In previous studies, some pharmaceutical effects of N. fruticans on melanogenesis and inflammation have been reported. The present study is conducted to investigate the effect of the ethyl acetate fraction of N. fruticans (ENF) on oxidative DNA damage and UVB-induced DNA damage. DNA damage response (DDR) pathway is important in research on cancer, apoptosis, and so on. DDR pathways are considered a crucial factor affecting the alleviation of cellular damage. ENF could reduce oxidative DNA damage derived from reactive oxygen species by the Fenton reaction. Also, ENF reduced the intensity of intracellular ROS in the live cell image by DCFDA assay. UVB is known to cause skin and cellular damage, then finally contribute to causing the formation of tumors. As for the strategies of reducing DNA damage by UVB, inhibition of p53, H2AX, and Chk2 can be important indexes to protect the human body from DNA damage. As a result of confirming the protective effect of ENF for UVB damage, MMPs significantly decreased, and the expression of apoptosis-related factors tended to decrease. In conclusion, ENF can provide protective effects against double-stranded DNA break (DSB) caused by oxidative DNA damage and UVB-induced DNA damage. These results are considered to be closely related to the protective effect against radicals based on catechin, epicatechin, and isoquercitrin contained in ENF. Based on these results, it is thought that additional mechanism studies for inhibiting cell damage are needed.

• 대한환경공학회지
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• 제32권6호
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• pp.547-554
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• 2010

본 연구에서는 나노구조의 새로운 망간산화물 입자(즉, 블랙-버네사이트)를 합성하여 물질특성 및 1,4-naphthoquinone (1,4-NPQ)을 대상으로 반응매개체 존재 하에서의 산화-변환반응 효율을 조사하였고, 그 결과를 기존의 McKenzie 방법으로 얻은 망간산화물(즉, 브라운-버네사이트)의 결과와 비교 분석하였다. XRD 분석 결과 합성한 망간산화물 입자의 결정상은 버네사이트(${\delta}-MnO_2$)임을 확인하였으며, SEM 측정결과 입자표면은 섬유상의 구조에 의한 나노크기의 미세기공을 가진 볼모양(ball-like)의 형태를 보였다. 배치실험 결과, 나노구조의 망간산화물에 의한 1,4-NPQ 제거는 유사-1차 반응을 따랐으며 기존 망간산화물과 비교해 BET 비표면적 값이 작음(41.05 vs 19.80 $m^2/g$)에도 불구하고 약 2.3배의 높은 속도 상수값을 보였다. 이러한 결과는 블랙-버네사이트에서의 상대적으로 높은 결정성과 나노구조의 표면 특성에 기인한 것으로 해석되며, 블랙-버네사이트 입자가 퀴논화합물에 대하여 상대적으로 높은 반응성을 보임을 알 수 있다. 반응산물에 대한 HPLC 크로마토그램 분석 결과로부터 블랙 버네사이트 입자에 의한 1,4-NPQ의 제거는 반응 매개체인 catechol 존재 하에서의 상호-결합반응을 통한 중합체 생성을 통해 제거됨을 확인하였다.

• 동의생리병리학회지
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• 제27권6호
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• pp.771-781
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• 2013

This study was performed to investigate the anti-photoaging effects of Persimmon leaf tea(PLT) in hairless mice(SKH-1) exposed to UVB irradiation. The animals were divided into non-treated group (normal, N) and UV-radiated groups. UV-radiated groups were divided into only UV-radiated group(control, C) and UV-radiated and PLT treated experimental groups[first extraction treated group(PLT-I), second extraction treated group(PLT-II), and third extraction treated group(PLT-III)]. Three PLT treated experimental groups of mice were treated with both oral administration(300 mg/Kg B.W./day) and topical application (100 ul of 2% conc./mouse/day) for 4 weeks. Anti-photoaging effects of Persimmon leaf were evaluated by anti oxidative reaction, stereomicroscopic and microscopic observations. The expression of photoaging skin related factors including mast cell tryptase, proliferating cell nuclear antigen (PCNA) and vascular endothelial growth factor (VEGF) was examined by immunohistochemical staining. Treatment of PLT-I, -II, -III prevented the wrinkle formation as well as epidermal hyperplasia, inflammatory cells, disruption of collagen in photoaged skin induced by UVB radiation. It also reduced the PCNA and VEGF expression in the UVB irradiated dorsal skin. Furthermore, it significantly decreased the number of mast cells in the UVB irradiated dermis(p<0.05 and p<0.01). On the effects of oxidative stress and antioxidant function on the treatment with water extract from Persimmon leaf tea(PLT), the activity of superoxide dismutase(SOD) was significantly increased in PLT-III group(p<0.05), and catalase(CAT) was significantly increased in PLT-I and PLT-III groups(p<0.05), and PLT-II group(p<0.001). These extracts showed relatively antioxidant activity and protective effect on UVB-induced oxidative stress in hairless mice(SKH-1). Our results suggest that Persimmon leaf tea may serve as an useful radical scavenging antioxidant and anti-photoaging skin agents in the UVB irradiated skin.

• Korean Chemical Engineering Research
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• 제45권5호
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• pp.424-432
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• 2007

바이오디젤은 식물유지 및 동물유지와 같은 재생 가능한 자원으로부터 얻어지는 친환경 대체에너지로서 주목받고 있다. 바이오디젤은 식물유지 또는 동물성 지방으로부터 얻어지는 긴사슬 지방산의 모노알킬에스터이다. 본 총설에서는 (1) 바이오디젤을 얻기위한 전이에스테로화 반응에 대한 촉매의 타입, 자유지방산 및 수분, 알콜과 유지의 반응비, 알콜타입, 반응온도 및 시간과 교반강도의 영향, (2) 전이에스테르화 이후의 바이오디젤에 대한 분리공정, 그리고 (3) 대체에너지로서 바이오디젤의 내연기관 적합성을 바이오디젤의 물성에 기초하여 소개한다.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.249-252
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• 2004

Cytochrome P450 (P450)/$O_2$/NADPH engender electron transfer reaction of N-benzyl-N-substituted benzylamines to yield corresponding radical cation 1 that is simultaneously converted into 2 and 3. Subsequently, expulsion of proton and hydroxylation yielding a-hydroxylamines are followed by formation of benzaldehydes and benzylamines.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.317.2-317.2
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• 2002

Peroxynitrite, formed from the reaction of .O2- and .NO, is a cytotoxic species that can oxidize several cellular components such as proteins. lipids and DNA. Oxidative stress is considered to be the major cause of aging and many age-related diseases including Alzheimer's disease. rheumatoid arthritis. cancer. and atherosclerosis. ONO-, a powerful oxidant, can cause damage of proteins, lipid and DNA through nitration and oxidation. (omitted)

• Journal of Applied Biological Chemistry
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• 제63권4호
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• pp.327-334
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• 2020

산화적 스트레스는 신경퇴행성 질환 발병의 원인으로 알려져 있다. 본 연구는 대표적인 감초 종류인 Glycyrrhiza glabra, G. uralensis와 신품종 감초인 신원감(SW)의 in vitro free radical 소거능을 통한 항산화 활성과 H2O2 유도 산화적 스트레스에 대한 C6 glial cell 보호 효능을 확인하고자 하였다. In vitro assay에서 G. uralensis, G. glabra, SW 추출물은 농도유의적으로 2,2-diphenyl-1-picrylhydrazyl, ·OH, O2- radical 소거능이 증가하여 in vitro 항산화 활성을 확인하였다. 또한, SW 추출물은 G. uralensis, G. glabra 추출물에 비해 총 페놀 및 플라보노이드 함량이 가장 우수하였다. H2O2로 산화적 스트레스를 유도한 C6 glial cell에 3가지 감초 추출물을 각각 처리 시, 농도의존적으로 세포 생존율이 증가와 reactive oxygen species 소거능이 증가하여 3가지 감초 추출물의 산화적 손상에 대한 신경교세포 보호 효과를 확인하였다. 특히, SW 추출물은 G. uralensis, G. glabra 추출물에 비해 우수하게 C6 glial cell 보호 효과를 나타내었다. 또한, 3가지 감초 추출물의 신경교세포 보호 메커니즘을 확인하기 위해, 염증 관련 단백질 발현을 측정하였다. 3가지 감초 추출물은 H2O2만을 처리한 control군에 비해 inducible nitric oxide synthase 및 cyclooxygenase-2 발현 감소를 통해 염증반응 조절을 통한 신경교세포 보호 작용기전을 확인하였다. 본 연구는 G. uralensis, G. glabra, SW 등 3가지 감초 추출물이 산화적 손상이 유도된 신경교세포 보호에 유용한 소재로써의 가능성이 있는 것으로 사료된다.