• Title/Summary/Keyword: redox system

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Alkaline and Antioxidant Effects of Bamboo Salt (죽염의 알칼리성 및 항산화 효과)

  • Zhao, Xin;Jung, Ok-Sang;Park, Kun-Young
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.41 no.9
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    • pp.1301-1304
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    • 2012
  • Mineral contents of various salts were determined by the ICP-OES method. Bamboo salt (baked 9 times) contained more potassium, calcium, magnesium, and manganese, compared to purified and solar salts. Bamboo salt had a pH of 11.04, higher than those of purified (6.29) and solar (9.13) salts. Contents of [$OH^-$] were measured by using the FT-IR spectra. Bamboo salt exhibited higher reduction potential and contained more OH groups than purified and solar salts. The reduction peak of bamboo salt was observed to be about three times broader than that of solar salt in terms of redox potential amperometry. At a salt concentration of 25%, bamboo salt showed higher radical scavenging activities (81.4%) than solar (5.0%) and purified (2.0%) salts, as evaluated by DPPH assay. Bamboo salt revealed alkaline property, more OH groups and antioxidative activity.

Self-Assembly and Electrochemical Properties of Viologen Particles (Viologen 분자의 자기조립과 전기화학적 특성)

  • Lee, Dong-Yun;Park, Sang-Hyun;Shin, Hoon-Kyu;Kwon, Young-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.452-455
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    • 2004
  • In this paper, investigations of the SAMs(self-assembled monolayers) of a thiol-fuctionalized viologen derivatives, $V_8SH$ and $SH_8V_8SH$, where, V is N,N'-dialkylbipyridinium (i.e. a viologen group), have been carried out by elucidate voltammetry date. The redox reactions are highly reversible and can be cycled many times without significant side reaction, which has been known as a nano-gram order mass detector through resonant frequency change self-assembly process of the viologen has been investigated with $QCM({\Delta}F)$. The assembling process of the $V_8SH$ and $SH_8V_8SH$ monolayers can be finished completely in about 1 hour. The measured frequency shift for $V_8SH$ and $SH_8V_8SH$ were about 351 and 172 Hz, respectively. From these values, we calculated that the mass adsorbed $V_8SH$ and $SH_8V_8SH$ were about 375 and 183 ng. We believe that this mass loss is caused by the simultaneous loss of the anions present within the monolayer for charge compensation of the viologen dications and some solvent.

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Epigenetic and Glucocorticoid Receptor-Mediated Regulation of Glutathione Peroxidase 3 in Lung Cancer Cells

  • An, Byung Chull;Jung, Nak-Kyun;Park, Chun Young;Oh, In-Jae;Choi, Yoo-Duk;Park, Jae-Il;Lee, Seung-won
    • Molecules and Cells
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    • v.39 no.8
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    • pp.631-638
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    • 2016
  • Glutathione peroxidase 3 (GPx3), an antioxidant enzyme, acts as a modulator of redox signaling, has immunomodulatory function, and catalyzes the detoxification of reactive oxygen species (ROS). GPx3 has been identified as a tumor suppressor in many cancers. Although hyper-methylation of the GPx3 promoter has been shown to down-regulate its expression, other mechanisms by which GPx3 expression is regulated have not been reported. The aim of this study was to further elucidate the mechanisms of GPx3 regulation. GPx3 gene analysis predicted the presence of ten glucocorticoid response elements (GREs) on the GPx3 gene. This result prompted us to investigate whether GPx3 expression is regulated by the glucocorticoid receptor (GR), which is implicated in tumor response to chemotherapy. The corticosteroid dexamethasone (Dex) was used to examine the possible relationship between GR and GPx3 expression. Dex significantly induced GPx3 expression in H1299, H1650, and H1975 cell lines, which exhibit low levels of GPx3 expression under normal conditions. The results of EMSA and ChIP-PCR suggest that GR binds directly to GRE 6 and 7, both of which are located near the GPx3 promoter. Assessment of GPx3 transcription efficiency using a luciferase reporter system showed that blocking formation of the GR-GRE complexes reduced luciferase activity by 7-8-fold. Suppression of GR expression by siRNA transfection also induced down-regulation of GPx3. These data indicate that GPx3 expression can be regulated independently via epigenetic or GR-mediated mechanisms in lung cancer cells, and suggest that GPx3 could potentiate glucocorticoid (GC)-mediated anti-infla-mmatory signaling in lung cancer cells.

Expression of Cytoplasmic 8-oxo-Gsn and MTH1 Correlates with Pathological Grading in Human Gastric Cancer

  • Song, Wen-Jie;Jiang, Ping;Cai, Jian-Ping;Zheng, Zhi-Qiang
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.15
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    • pp.6335-6338
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    • 2015
  • Background: Cancers have dysfunctional redox regulation resulting in production of reactive oxygen species (ROS), damaging DNA, RNA and free NTPs, and causing the accumulation of oxidative nucleic acids in cytoplasm. The major types are 8-oxo-7,8-dihydroguanine(8-oxoGsn) in RNA and 8-oxo-7,8-dihydro-2' deoxyguanosine(8-oxodGsn) in Mt-DNA. The MTH1 protein sanitizes oxidized nucleotide pools from NTPs to monophosphates, preventing the occurrence of transversion mutations. This study concerned cytoplasmic 8-oxodGsn/Gsn and MTH1 expression in gastric cancer and para-cancer tissues and elucidated roles of nucleic-acid oxidation and anti-oxidation. Materials and Methods: A polymer HRP detection system was used to detect 8-oxo-Gsn/dGsn and MTH1 expression in 51 gastric cancer and para-cancer tissue samples. Analyses of patient clinical and pathological data were also performed. Results: The expression of MTH1 and the 8-oxo-dGsn/Gsn ratio were significantly higher in cancer tissues than para-cancer tissues (P<0.05). Cytoplasmic 8-oxo-Gsn and MTH1 were both found to positively correlate (P<0.05) with tumor differentiation, while no significant associations were found with gender, age, invasion depth, lymph node metastasis and clinical stage (P>0.05). Conclusions: We found 8-oxo-dGsn/Gsn and MTH1 are both highly expressed in gastric cancer tissues, especially in well differentiated lesions. In addition, oxidated mtDNA is prevalently expressed in gastric cancers, while 8-oxo-Gsn expression in cytoplasmic RNA is a bit lower, but more selectively.

Influence of Iron Phases on Microbial U(VI) Reduction

  • Lee, Seung-Yeop;Baik, Min-Hoon;Lee, Min-Hee;Lee, Young-Boo;Lee, Yong-Jae
    • Journal of Soil and Groundwater Environment
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    • v.16 no.6
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    • pp.58-65
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    • 2011
  • The bacterial uranium(VI) reduction and its resultant low solubility make this process an attractive option for removing U from groundwater. An impact of aqueous suspending iron phase, which is redox sensitive and ubiquitous in subsurface groundwater, on the U(VI) bioreduction by Shewanella putrefaciens CN32 was investigated. In our batch experiment, the U(VI) concentration ($5{\times}10^5M$) gradually decreased to a non-detectable level during the microbial respiration. However, when Fe(III) phase was suspended in solution, bioreduction of U(VI) was significantly suppressed due to a preferred reduction of Fe(III) instead of U(VI). This shows that the suspending amorphous Fe(III) phase can be a strong inhibitor to the U(VI) bioreduction. On the contrary, when iron was present as a soluble Fe(II) in the solution, the U(VI) removal was largely enhanced. The microbially-catalyzed U(VI) reduction resulted in an accumulation of solid-type U particles in and around the cells. Electron elemental investigations for the precipitates show that some background cations such as Ca and P were favorably coprecipitated with U. This implies that aqueous U tends to be stabilized by complexing with Ca or P ions, which easily diffuse and coprecipitate with U in and around the microbial cell.

Themochemical Cycles for Hydrogen Production from Water (열화학적 수소 제조 기술)

  • Kim J.W.;Park C.S.;Hwang G.J.;Bae K.K.
    • Journal of Energy Engineering
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    • v.15 no.2 s.46
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    • pp.107-117
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    • 2006
  • The status of water splitting thermochemical cycle for hydrogen production was reviewed in this article. Mass production of hydrogen could be possible using the thermochemical process which is similar to the concept of conventional chemical reaction system if the high temperature heat source is available. The mediators (chemicals and reagents) should be used to split chemically stable water, and should be recycled in a closed cycle in order to be environmentally acceptable. Though there is no process to reach commercial stage, IS cycle, two-step cycles based on metallic oxide such as ZnO/Zn, $Fe_3O_4/FeO$ and the associated cycles are attracted due to their possibilities of application. Development of materials for high temperature and/or corrosive conditions during thermochemical process is still important topic in some thermochemical processes.

Study on the Emulsion Polymerization of poly(vinyl acetate-co-ethylene) Using Poly(vinyl alcohol) as Emulsifier (Poly(vinyl alcohol)을 이용한 Poly(vinyl acetate-co-ethylene) Emulsion 중합에 대한 연구)

  • Choi, Yong-Hae;Lee, Won-Ki
    • Journal of Adhesion and Interface
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    • v.11 no.3
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    • pp.89-99
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    • 2010
  • In this paper, for polymerization of poly(vinyl acetate-co-ethylene) (VAE) by redox system using poly(vinyl alcohol) (PVOH) as emulsifier on the properties of the final emulsion, and pH changes affect the physical properties of the final emulsion was investigated. The results of the molecular weight of PVOH had a dramatic impact on the emulsion properties. The used a low molecular weight of PVOH products was obtained low viscosity and using the high molecular weight of PVOH were obtained high viscosity product. However, changing the pH of the final polymerized product properties for the PVOH obtained different results. Generally, a poly(vinyl acetate) emulsion by a high degree of polymerization and high molecular weight of PVOH was obtained high viscosity of the final emulsion. But, in VAE was lower emulsion viscosity in high pH. This is the molecular weight of the emulsion during the synthesis of PVOH is considered to be affected by degradation. The final viscosity was decreased by grafting ratio and molecular weight were decreased with increasing of pH.

The Effect of NaCl on the Greening of Etiolated Leaves of Barely (Hordeum vulgare L.) Seedings (NaCl이 황백화된 보리(Hordeum vulgare L.) 잎의 녹화에 미치는 영향)

  • 정화숙;임영진;송승달;노광수;송종석;박강은
    • Journal of Environmental Science International
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    • v.11 no.10
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    • pp.1023-1030
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    • 2002
  • The effects on photosynthesis of NaCl(0, 0.2, 0.4, 0.6, 0.8 or 1.0 M) were examined in etiolated barley seedlings. Chlorophyll(Chl) a, Chl b and carotenoid contents, Chl a fluorescence and quenching coefficients of Chl fluorescence have been determined in the primary leaves of etiolated barley seedlings cultivated under low light(60 $\mu$$m^{-2}\;s^{-1}$). Chl a, b, and carotenoid contents were decreased remarkably in comparison with the control at 0.4 M NaCl. However, the value of Fo and Fv were decreased at 0.6 M NaCl and the ratio of Fv/Fm were deceased at 1.0 M NaCl. Chlorophyll synthesis was seriously inhibited from 0.4 M NaCl, and the photosynthetic electron transport system was inhibited from 0.6 M NaCl. Quantum of photosystem II reaction center was inhibited at 1.0 M NaCl. The effects of NaCl on the Chl content were raised in a 6 hrs, but the effects of NaCl on the value of Fo, Fv and Fv/Fm were raised in 30 hrs. The value of qP was decreased in comparison with the control at all concentrations, but there was a small change in the value qE. These results provide evidence that NaCl inhibited effects of various concentration of NaCl were inhibited quinone redox, however, proton gradient between thylakoid membranes was little damaged.

Study on Possibility of PrBaMn2O5+δ as Fuel Electrode Material of Solid Oxide Electrolysis Cell (이중 페로브스카이트 촉매 PrBaMn2O5+δ의 고온전기분해조(Solid Oxide Electrolysis Cell) 연료극 촉매로 적용 가능성에 대한 연구)

  • Kwon, Youngjin;Kim, Dongyeon;Bae, Joongmyeon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.20 no.4
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    • pp.491-496
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    • 2017
  • The hydrogen($H_2$) is promising energy carrier of renewable energy in the microgrid system such as small village and military base due to its high energy density, pure emission and convenient transportation. $H_2$ can be generated by photocatalytic water splitting, gasification of biomass and water electrolysis driven by solar cell or wind turbine. Solid oxide electrolysis cells(SOECs) are the most efficient way to mass production due to high operating temperature improving the electrode kinetics and reducing the electrolyte resistance. The SOECs are consist of nickel-yttria stabilized zirconia(NiO-YSZ) fuel electrode / YSZ electrolyte / lanthanum strontium manganite-YSZ(LSM-YSZ) air electrode due to similarity to Solid Oxide Fuel Cells(SOFCs). The Ni-YSZ most widely used fuel electrode shows several problems at SOEC mode such as degradation of the fuel electrode because of Ni particle's redox reaction and agglomeration. Therefore Ni-YSZ need to be replaced to an alternative fuel electrode material. In this study, We studied on the Double perovskite $PrBrMnO_{5+{\delta}}$(PBMO) due to its high electric conductivity, catalytic activity and electrochemical stability. PBMO was impregnated into the scaffold electrolyte $La_{0.8}Sr_{0.2}Ga_{0.85}Mg_{0.15}O_{3-{\delta}}$(LSGM) to be synthesized at low temperature for avoiding secondary phase generated when it exposed to high temperature. The Half cell test was conducted at SOECs and SOFCs modes.

Development of DNA Hybridization Detection Sensors and Analysis of Characteristics Using Electrochemical methods (전기화학법을 이용한 DNA Hybridization 검출 센서의 개발 및 특성 해석)

  • Ock, Jin-Young;Kim, Do-Kyun;Chang, Jeong-Soo;Kwon, Young-Soo
    • Proceedings of the KIEE Conference
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    • 2002.11a
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    • pp.260-262
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    • 2002
  • The determination of DNA hybridization can apply the molecular biology research. clinic diagnostics. bioengineering, environment monitoring, food science and other application area. So, The determination of hybridization is very important for the improvement of DNA detection system. In this study, we report the characterization of the DNA hybridization by the electricalchemical methods. The probe oligonucleotide was used to determine the amount of target oligonucleotide in solution using Methylen Blue(MB) as the electrochemical indicators. The cathodic peak currents($I_{peak}$) of MB were linearly related to the concentration of the target oligonucleotide sequence in the range $1[{\mu}M]{\sim}0.1[{\mu}M]$. The detection limit of this approach was 0.01[nM]. As a result, the match oligonucleotide(CR-1) was most stable state and the peak of redox current measured by DNA hybridization detection sensors by using electrochemical method seem to be similar to 1-mer terminal mismatch oligonucleotide(MR-3). The MR-2, MR-3, MR-22 and MR-33 have each mismatching sequence of central and terminal. With this set the role of point mutations was to be investigated. Terminal mismatch oligonucleotide (MR-3, 33) is shown more stable state than central mismatch oligonucleotide(MR-2, 22). And 1-mer mismatch oligonucleotide(MR-2 or 3) is shown more stable state than 2-mer mismatch oligonucleotide(MR-22 or 33).

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