• Environmental Analysis Health and Toxicology
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• 제12권3_4호
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• pp.1-13
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• 1997

First- and second-order kinetic oxidation rates of trichlorobenzenes (TCBs) were obtained and compared by a chemical activation system (CAS) which mimics mixed functional oxidase activity. The system consists of EDTA, ferrous sulfate, ascorbic acid, and $H_2O_2$ in potassium phosphdte buffer (monobasic at pH 7.4). The rate of transformation in CAS was enhanced in the presence and absence of catalase in the sequence 1, 2, 3-TCB < 1, 2, 4-TCB < 1, 3, 5-TCB. In general, the rates of degradation were greater in the test media with catalase. The effect of photolysis on the degradation of the TCBs with the CAS were examined. Sensitized photolysis with nitrite, Fenton's reagent, TiO$_2$ and triethylamine (TEA) studied in concert with the CAS demonstrated significant enhancement of the degradation rate of TCBs. Disappearance rates of TCBs in CAS with prior photolysis or prior photosensitization were at least 10-fold higher than the sum of the rate for each single experiment. This study proves that the combination of the CAS and photolysis can be used as a suitable technique for enhancing degradation of TCBs in aqueous systems.

• 한국환경성돌연변이발암원학회:학술대회논문집
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• 한국환경성돌연변이발암원학회 2001년도 Korean Environmental Mutagen Society
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• pp.175-175
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• 2001

• 동의생리병리학회지
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• 제20권1호
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• pp.76-82
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• 2006

This study was purposed to investigated the antioxidant effects of water (VLWS) and aqua-acupuncture solution (VLAS) from root of Vitis labrusca. VLWS and VLAS was were assessed to determine the mechanisms of its antioxidant activities. The VLWS and VLAS exhibitde a concentration-dependent inhibition of DPPH free radicals. This VLWS-mediated antioxidant activity was similar to that L-ascorbic acid (vitamin C). In addition, the VLWS and VLAS showed dose-dependent free radical scavenging activity, including superoxide anions and hydroxyl radicals, using different assay systems. The VLWS and VLAS were also found to be strongly inhibited linoleic acid oxidation in a ferric thiocyanate assay (FTC) system. Finally, the VLWS and VLAS significantly prevented Fenton's reagent-induced DNA nicking.

• Bulletin of the Korean Chemical Society
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• 제1권3호
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• pp.113-114
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• 1980

Lumichrome (7,8-dimethylalloxazine) exhibits two fluorescence emission maxima at 440 and 540 nm in pyridine-dioxane. These emission band maxima are attributable to radiative decays from the excited states of lumichrome and its flavin tautomer, 7,8-dimethylisoalloxazine, respectively. The growth of the latter can be followed upon excitation of the former with a 2-nanosecond light pulse generated from the nitrogen plasma discharge lamp. The excited state tautomerism results from proton transfer from N-1 to N-10 position during the lifetime of the lumichrome singlet excited state. The rate depends on the concentration of general base, pyridine, and it is an order of magnitude slower than diffusion-controlled processes.

• Journal of Microbiology and Biotechnology
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• 제33권8호
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• pp.992-997
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• 2023

Ferroptosis is a new kind of programmed cell death of which occurrence in microorganisms is not clearly verified. The elevated level of reactive oxygen species (ROS) influences cellular metabolisms through highly reactive hydroxyl radical formation under the iron-dependent Fenton reaction. Iron contributes to ROS production and acts as a cofactor for lipoxygenase to catalyze poly unsaturated fatty acid (PUFA) oxidation, exerting oxidative damage in cells. While ferroptosis is known to take place only in mammalian cells, recent studies discovered the possible ferroptosis-like death in few specific microorganisms. Capacity of integrating PUFA into intracellular membrane phospholipid has been considered as a key factor in bacterial or fungal ferroptosis-like death. Vibrio species in bacteria and Saccharomyces cerevisiae in fungi exhibited certain characteristics. Therefore, this review focus on introducing the occurrence of ferroptosis-like death in microorganisms and investigating the mode of action underlying the cells based on contribution of lipid peroxidation and iron-dependent reaction.

• 한국해양공학회지
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• 제37권6호
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• pp.256-265
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• 2023

Many numerical methods have been developed since 1961, but unresolved issues remain. This study developed a numerical method to address these issues and determine the coefficients and properties of rotational waves with a shear current in a finite water depth. The number of unknown constants was reduced significantly by introducing a wavelength-independent coordinate system. The reference depth was calculated independently using the shooting method. Therefore, there was no need for partial derivatives with respect to the wavelength and the reference depth, which simplified the numerical formulation. This method had less than half of the unknown constants of the other method because Newton's method only determines the coefficients. The breaking limit was calculated for verification, and the result agreed with the Miche formula. The water particle velocities were calculated, and the results were consistent with the experimental data. Dispersion relations were calculated, and the results are consistent with other numerical findings. The convergence of this method was examined. Although the required series order was reduced significantly, the total error was smaller, with a faster convergence speed.

• 공업화학
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• 제10권1호
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• pp.24-29
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• 1999

천연 토양 속에 많이 존재하는 철광석인 goethite, magnetite와 과산화수소수를 이용해 펜톤 유사 반응(Fenton-like oxidation)을 유도하여 디젤과 등유가 같은 중량 비율로 오염된 silica sand를 회분식 시스템으로 처리하여 보았다. 과산화수소수의 pH(3, 7) 농도(0%, 1%, 7%, 15%, 35%), 초기 오염물의 농도(0.2, 0.5, 1.0 g-오염물/kg-모래), 그리고 철광석(iron minerals)의 양(0, 1, 5 wt % magnetite 또는 goethite)을 달리하여 반응조건들을 조사하였다. Silica sand-철광석-$H_2O_2$ system에서의 오염물의 분해는 잔존 Total Petroleum Hydrocarbon(TPH)의 농도를 분석하여 확인하였다. 최적 실험 pH는 3이었고, 철광석이 철공급원으로 사용된 경우가 $FeSO_4$ 용액이 철공급원으로 사용된 경우보다 과수의 소모가 적어서 더 효율적이었다. 초기 오염물의 농도 1.0 g-오염물/kg-모래(5 wt % magnetite)에 과산화수소수의 농도를 0%, 1%, 7%, 15%, 그리고 35%로 달리하여 본 결과 8일후 각각 0%, 24.5%, 44%, 50%, 그리고 70%의 TPH 감소를 보였다. 같은 오염물 농도하에서 15%의 과산화수소를 사용하고, 철광석의 양이 0, 1, 5, 10 wt %로 변화되었을 경우, 오염물의 제거량은 magnetite의 사용시 각각 0%, 33.5%, 50%, 60%, goethite의 사용시는 각각 0%, 29%, 41%, 53%이었다. Magnetite system은 iron(II)과 iron(III)이 공존하며, 미량의 철성분이 용해되므로 goethite system보다 오염물의 분해가 더 많이 일어나는 것으로 보인다. 그러나 용해된 철성분은 철광석 표면에 침전물의 형태로 쌓이게 되어 철광석 표면의 전자교환능력을 감소시키고 과산화수소수를 quenching시키는 것으로 사려된다. 그리하여 goethite system에서 과산화수소수가 적게 소모되어 magnetite system보다 나은 처리효율을 가지는 것으로 나타났다. 토양을 shaker를 이용하여 혼합시킨 결과 오염물의 제거량이 magnetite의 경우 41%, goethite의 경우 30%만큼 증가하였다. 이 연구의 결과를 통하여 볼 때 천연토양속에는 magnetite와 goethite같은 철광석이 함유되어 있으므로 별도의 철성분 첨가없이 과산화수소수의 처리만으로도 석유로 오염된 토양의 in-situ 또는 ex-situ한 처리가 가능할 것으로 보인다.

• Applied Biological Chemistry
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• 제47권1호
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• pp.61-66
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• 2004

신선찰거대배아미, 화청거대배아미 및 남풍거대배아미 등 거대배 돌연변이 계통 쌀 3종류 및 일반미의 70% 에탄올 추출물을 제조하여, 이들의 항산화 활성 및 항변이원성을 비교 검정하였다. 거대배아미 추출물의 항산화 활성은 DPPH radical 및 Fenton 반응에 의해서 유도되는 hydroxy radical의 소거활성, hypoxanthine/xanthine oxidase system에서 생성되는 활성산소종인 superoxide radical의 소거활성, linoleic acid자동산화에 대한 지질 과산화 억제활성 및 토끼 적혈구 막지질의 과산화 억제활성 둥으로써 검정하였으며, 항변이원성은 E. coli PQ 37 균주를 사용하여 화학적 변이원 mitomycin C에 대한 변이원성 억제효과를 SOS chromotest에 의해서 검정하였다. 일반미 품종에 비해서 거대배아미 품종의 항산화 활성 및 항변이원성이 모두 높았으며, 거대배아미 품종 중에서는 남풍거대배아미가 가장 효과적인 경향이 있었다. 남풍거대배아미의 DPPH radical, superoxide radical과 hydroxyl radical 소거활성, 그리고 지질과산화 억제활성은 일반미보다 각각 2.3배, 3.3배, 1.7배 및 2.5배 정도까지 더 높았다.

• 생명과학회지
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• 제25권9호
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• pp.1000-1006
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• 2015

α-Asarone은 동양의 전통적인 약재로 잘 알려진 석창포(Acorus gramineus)의 주된 성분이다. 석창포는 항위궤양, 항알러지, 히스타민 방출 억제 그리고 항산화 효과와 같이 다양한 효과를 나타내는 것으로 잘 알려져 있다. 그러나 석창포 역할에 대한 기전연구는 아직 부족한 실정이다. 본 연구에서는, HT1080 세포주에서 α-asarone의 항산화 효과뿐만 아니라 matrix metalloproteinase에 대한 효과를 조사하였다. 가장 먼저 α-asarone의 세포 생존에 대한 효과를 조사하기 위해 MTT assay를 이용하여 16 μM이하에서 세포독성이 없음을 나타내었다. α-asarone이 환원력과 fenton reaction에 의해 유도된 DNA 산화로부터 보호효과를 나타내는 것을 확인하였다. 더욱이, α- asarone은 collagenase 활성을 증가시키고 phorbol 12-myristate 13-acetate (PMA)로 자극된 MMP-2 및 MMP-9의 활성을 증가시켰다. 한편 phenazine methosulfate (PMS) 로 자극된 경우 MMP-9의 활성은 α-asarone의 존재하에서 증가되었으나 MMP-2 활성에는 변화가 없었다. 그러므로 우리의 연구결과는 α-asarone이 산화적 스트레스 및 MMPs와 관련된 병리학적 질환의 예방 및 치료제로 개발이 기대된다고 제안한다.

• 한국환경과학회지
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• 제23권5호
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• pp.903-910
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• 2014

This study examined the treatment characteristics of hard-to-degrade pollutants such as TCE which are found in organic solvent and cleaning wastewater by nZVI that have excellent oxidation and reduction characteristics. In addition, this study tried to find out the degradation characteristics of TCE by Fenton-like process, in which $H_2O_2$ is dosed additionally. In this study, different ratios of nZVI and $H_2O_2$, such as 1.0 mM : 0.5 mM, 1.0 mM : 1.0 mM, and 1.0 mM : 2.0 mM were used. When 1.0 mM of nZVI was dosed with 1.0 mM of $H_2O_2$, the removal efficiency of TOC was the highest and the first order rate constant was also the highest. When 1mM of nZVI was dosed with 0.5 mM of $H_2O_2$, the first order rate constant and removal efficiency were the lowest. The size of first order rate constant and removal efficiency was in the order of nZVI 1.0 mM : $H_2O_2$ 1.0 mM > nZVI 1.0 mM : $H_2O_2$ 2.0 mM > nZVI 1.0 mM : $H_2O_2$ 0.5 mM > $H_2O_2$ 1.0 mM > nZVI 1.0 mM. It is estimated that when 1.0 mM of nZVI is dosed with 1.0 mM of $H_2O_2$, $Fe^{2+}$ ion generated by nZVI and $H_2O_2$ react in the stoichiometric molar ratio of 1:1, thus the first order rate constant and removal efficiency are the highest. And when 1.0 mM of nZVI is dosed with 2.0 mM of $H_2O_2$, excessive $H_2O_2$ work as a scavenger of OH radicals and excessive $H_2O_2$ reduce $Fe^{3+}$ into $Fe^{2+}$. As for the removal efficiency of TOC in TCE by simultaneous dose and sequential dose of nZVI and $H_2O_2$, sequential dose showed higher first order reaction rate and removal efficiency than simultaneous dose. It is estimated that when nZVI is dosed 30 minutes in advance, pre-treatment occurs and nanoscale $Fe^0$ is oxidized to $Fe^{2+}$ and TCE is pre-reduced and becomes easier to degrade. When $H_2O_2$ is dosed at this time, OH radicals are generated and degrade TCE actively.