• 전기화학회지
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• 제22권3호
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• pp.79-86
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• 2019

중저온 (<$200^{\circ}C$) 폐열은 중요한 청정 에너지원이다. 폐열 활용 방안 중 가장 대표적인 것은 열전기술이나, 최근 전기화학 열전지가 열전소자의 대안으로 주목받고 있다. 전기화학 열전지의 기전력은 산화/환원 전극 전위의 온도 의존성에 의해 발생하며, 출력 특성은 전기화학 반응에 수반되는 동역학과 물질 이동 과전압에 의해 결정된다. 전기화학 열전지는 열전소자보다 비용 및 설계 유연성이 장점이지만, 열전소자에 비해 낮은 열-전기 변환 효율로 인해 응용 범위가 제한되어왔다. 하지만 최근 새로운 전해질과 전극을 적용하여 전기화학 열전지의 성능을 크게 향상할 수 있음이 보고되고 있다. 이 총설은 전기화학 열전지용 산화/환원쌍, 수계/비수계 전해질과 첨가제, 전극 물질 및 전지 설계 측면에서 최근 연구 동향을 소개한다.

• Journal of Ceramic Processing Research
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• 제19권5호
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• pp.372-377
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• 2018

MgO or gadolinium-doped ceria (GDC, $Ce_{0.9}Gd_{0.1}O_{2-{\delta}}$) was added as a promoter to improve the oxygen transfer kinetics of $MgMnO_3$ oxygen carrier material for chemical looping combustion. Neither MgO nor GDC reacted with $MgMnO_3$, even at the high temperature of $1100^{\circ}C$. The average oxygen transfer capacities of $MgMnO_3$, 5 wt% $MgO-MgMnO_3$, and 5 wt% $GDC-MgMnO_3$ were 8.74, 8.35, and 8.13 wt%, respectively. Although the addition of MgO or GDC decreased the oxygen transfer capacity, no further degradation was observed during their use in 5 redox cycles. The addition of GDC significantly improved the conversion rate for the reduction reaction of $MgMnO_3$ compared to the use of MgO due to an increase in the surface adsorption process of $CH_4$ via oxygen vacancies formed on the surface of GDC. On the other hand, the conversion rates for the oxidation reaction followed the order 5 wt% $GDC-MgMnO_3$ > 5 wt% $MgO-MgMnO_3$ >> $MgMnO_3$ due to morphological change. MgO or GDC particles suppressed the grain growth of the reduced $MgMnO_3$ (i.e., (Mg,Mn)O) and increased the specific surface area, thereby increasing the number of active reaction sites.

• 공업화학
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• 제33권1호
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• pp.64-70
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• 2022

본 연구에서는 NH₃-SCR에서 VWTi촉매의 저온 탈질효율 증진을 위해 Sb을 첨가하여 실험을 수행하였으며 Sb 첨가에 있어 다양한 소성온도(400~700 ℃)에서 제조하였다. NH₃-SCR 실험 결과 Sb 소성온도 500~600 ℃에 해당하는 VWSbTi(500)와 VWSbTi(600) 촉매가 300 ℃ 이하의 저온에서 가장 우수한 탈질성능을 나타냈으며, 소성온도에 따른 물리화학적 특성을 확인하고자 BET, XRD, Raman, XPS, H₂-TPR, NH₃-TPD 분석을 수행하였다. VWSbTi(500)와 VWSbTi(600)의 경우 W=O종의 생성에 따라 암모니아 산점이 증가하였으며 텅스텐의 전자밀도 증가에 따른 우수한 redox 특성으로 저온에서 우수한 활성을 나타내었다. 또한 VWSbTi(700)의 경우 V₂O₅ 결정구조가 형성되어 활성이 저하됨에 따라 Sb 첨가과정에 있어 최적의 소성온도를 확인하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제27권1호
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• pp.9-20
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• 2023

The mechanism is unclear for the reported protective effect of hyperbaric oxygen preconditioning against oxidative stress in tissues, and the distinct effects of hyperbaric oxygen applied after stress. The trained mice were divided into three groups: the control, hyperbaric oxygenation preconditioning, and hyperbaric oxygenation applied after mild (fasting) or hard (prolonged exercise) stress. After preconditioning, we observed a decrease in basal levels of nitric oxide, tetrahydrobiopterin, and catalase despite the drastic increase in inducible and endothelial nitric oxide synthases. Moreover, the basal levels of glutathione, related enzymes, and nitrosative stress only increased in the preconditioning group. The control and preconditioning groups showed a similar mild stress response of the endothelial and neuronal nitric oxide synthases. At the same time, the activity of all nitric oxide synthase, glutathione (GSH) in muscle, declined in the experimental groups but increased in control during hard stress. The results suggested that hyperbaric oxygen preconditioning provoked uncoupling of nitric oxide synthases and the elevated levels of GSH in muscle during this study, while hyperbaric oxygen applied after stress showed a lower level of GSH but higher recovery post-exercise levels in the majority of antioxidant enzymes. We discuss the possible mechanisms of the redox response and the role of the nitric oxide in this process.

• Korean Chemical Engineering Research
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• 제61권1호
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• pp.162-167
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• 2023

망간산화물은 다양한 결정구조를 가지고 있으며, 특히 초기에 생성되는 나노층상구조의 δ-MnO₂ 가 다양한 산화환원 반응에 따라 여러가지 터널 및 층상구조로 변화한다. 최근Zn기반 이차전지에 대한 관심이 증가하고 있지만, 충방전 간 Zn이온이 양극재로 사용되는 망간산화물 결정 구조 변화 및 새로운 결정 생성 등에 미치는 영향에 대한 기초적 이해를 위해 Zn이온이 망간산화물 결정에 미치는 영향에 대한 연구가 더욱 필요하다. 본 연구에서는 수열반응 간 Zn 도핑정도가 조절된 나노층상구조의 δ-MnO₂의 변화를 통해 todorokite과 chalcophanite이 생성 및 성장되는 것을 확인하였고, 반응 시간에 따른 변화과정을 확인하였다. Zn의 양이 많을수록 chalcophanite 결정이 우세하게 생성되었고, 결정 생성이 상대적으로 느린 속도로 발생하는 것을 확인하였다.

• 동의생리병리학회지
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• 제30권4호
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• pp.242-249
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• 2016

This study was to investigate the anti-inflammatory effects of Prunellae Herba(PH). The generation of superoxide anion radical (․O₂-), nitric oxide (NO), peroxynitrite (ONOO-) and Prostaglandin E₂(PGE₂) were measured in the H₂O₂-Treated renal epithelial cells(LLC-PK1 cell) of mouse. And the effects of Prunellae Spica on the expression of NF-κB (p50, p65), IKK-α, phospho-IκB-α and inflammation-related proteins, COX-2, iNOS, IL-1β and VCAM-1, were examined by western blot. The fluorescent probes, 2',7'-dichlorodihydrofluorescein diacetate (DCFDA), 4,5-diaminofluorescein (DAF-2) and dihyldrorhodamine 123 (DHR 123) were used to estimate the scavenging effect of Prunellae Spica on ․O₂-, NO, ONOO-. Western blot was conducted to assess the protein expression levels of NF-κB (p50, p65), IKK-α, phospho-IκB-α, inflammation-related proteins, COX-2, iNOS, IL-1β, VCAM-1. PH inhibited H₂O₂-treated cell death dose-dependently. It reduced the generation of ·O₂-, NO, ONOO- and PGE₂ in the H₂O₂-treated renal epitheial cells(LLC-PK₁ cell) of mouse in vitro. PH reduced the expression of NF-κB, IKK-α, phospho-IκB-α, COX-2, iNOS, IL-1β and VCAM-1 genes through means of decreasing activation of NF-κB signaling as well. According to these results, PH has an antioxidative activity and anti-inflammatory effect by regulating the NF-κB pathway. This suggest that PH is expected to be used to regulating inflammatory process and treating inflammation-related disease.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.539-542
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• 1999

In this study, acrylate salt material of new chemical composition for injection grouting was prepared in the state of aqueous solution, and the chemical and physical properties of the material were investigated. The gelation time of the material was freely controllable through the control of added catalysts amount. As the viscosity of the material was very low (2∼3cps), its injection efficiency was expected to be very excellent. The variation of its viscosity plotted with the process of gelation revealed that the efficiency of its penetration into the ground soil was very excellent. The LD$\sub$50/ test on white mouse verified the toxicity of the material was very slight and substantially negligible. The grouting effect using the material was examined through field case histories.

• Biomolecules & Therapeutics
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• 제21권2호
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• pp.89-96
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• 2013

Atherosclerotic vascular dysfunction is a chronic inflammatory process that spreads from the fatty streak and foam cells through lesion progression. Therefore, its early diagnosis and prevention is unfeasible. Reactive oxygen species (ROS) play important roles in the pathogenesis of atherosclerotic vascular disease. Intracellular redox status is tightly regulated by oxidant and antioxidant systems. Imbalance in these systems causes oxidative or reductive stress which triggers cellular damage or aberrant signaling, and leads to dysregulation. Paradoxically, large clinical trials have shown that non-specific ROS scavenging by antioxidant vitamins is ineffective or sometimes harmful. ROS production can be locally regulated by cellular antioxidant enzymes, such as superoxide dismutases, catalase, glutathione peroxidases and peroxiredoxins. Therapeutic approach targeting these antioxidant enzymes might prove beneficial for prevention of ROS-related atherosclerotic vascular disease. Conversely, the development of specific antioxidant enzyme-mimetics could contribute to the clinical effectiveness.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.179-182
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• 2002

The objective of this study was to evaluate petroleum hydrocarbon degradation processes governing natural attenuation at tile contaminated site and accomplished through conducting on investigation of degradation rate, capacity, and mechanism of the monitored natural attenuation. The monitoring results of the three years indicated that the concentrations of DO, nitrate, and sulfate in the contaminated area were significantly lower than these in the none-contaminated area. The results also showed a higher ferrous iron concentration, a lower redox potential and a neutral pH in the contaminated groundwater, suggesting that biodegradation of TEX is the major on-going process in the contaminated area. However, reduction of TEX in the groundwater was not only biodegradation but also dilution and reaeration during infiltration of uncotaminated surface and groudwater.

• 한국자기공명학회논문지
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• 제11권1호
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• pp.48-55
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• 2007

NMR signals of two hemes were assigned to particular hemes in the crystal structures by nuclear Overhauser effect experiments. The results showed that the hemes with the highest and lowest redox potentials in the one-electron reduction process correspond to the hemes I and IV in the crystal structure.