• Title, Summary, Keyword: Oxidation-Reduction Potential

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Effect of Oxidation-Reduction Potential on Denitrification by Ochrobactrum anthropi SY509

  • Song, Seung-Hoon;Yeom, Sung-Ho;Choi, Suk-Soon;Yoo, Young-Je
    • Journal of Microbiology and Biotechnology
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    • v.13 no.3
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    • pp.473-476
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    • 2003
  • The effect of oxidation-reduction potential (ORP) level on the denitrification by Ochrobactrum anthropi SY509 was investigated under nongrowing condition. The maximum ORP level of nitrate-containing buffer solution was -70∼-80 mV, under which the denitrification took place. By decreasing the initial ORP level, denitrifying enzyme activity was greatly enhanced, which led to higher denitrification efficiency.

Relationship Between Tyrosinase Inhibitory Action and Oxidation-Reduction Potential of Cosmetic Whitening Ingredients and Phenol Derivatives

  • Sakuma, Katsuya;Ogawa, Masayuki;Sugibayashi, Kenji;Yamada, Koh-ichi;Yamamoto, Katsumi
    • Archives of Pharmacal Research
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    • v.22 no.4
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    • pp.335-339
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    • 1999
  • The oxidation-reduction potentials of cosmetic raw materials, showing tyrosinase inhibitory action, and phenolic compounds structurally similar to L-tyrosine were determined by cylcic voltammetry. The voltammograms obtained could be classified ito 4 patterns (patterns 1-4). Patterns 1, characterized by oxidation and reduction peaks as a pair, was observed with catechol, hydroquinone or phenol, and pattern 2 exhibiting another oxidation peak in addition to oxidation and reduction peaks as a pair was found with arbutin, kojic acid, resorcinol, methyl p-hydroxybenzoate and L-tyrosine as the substrate of tyrosinase. Pattern 3 with an independent oxidation peak only was expressed by L-ascorbic acid, and pattern 4 with a reduction peak only at high potentials, by hinokitiol. The tyrosinase inhibitory activity of these compounds was also evaluated using the 50% inhibitory concentration ($IC_{50}$) and the inhibition constant (Ki) as parameters. Hinokitiol, classified as patterns 4, showed the highest inhibitory activity (lowest $IC_{50}$ and Ki). Hydroquinone showing the second highest activity belonged to pattern 1, which also included compounds exhibiting pattern 2 was relatively low with Ki values being in the order of 10-4 M. Although there was no consistent relationship between oxidation-reduction potentials and tyrosinase inhibitory action, the voltammetry data can be used as an additional index to establish the relationship between the structure and the tyrosine inhibitory activity.

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The Effects of Electric Field Variation by The Third Electrode on Water Electrophysicochemical Characteristics (제3전극에 의한 전계변화가 수중 전기물리화학적 특성에 미치는 영향)

  • Kim, Jin-Gyu
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.9
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    • pp.136-141
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    • 2010
  • In this paper, after the third electrode type oxidant generator which could format non-uniform electric field in water had been manufactured and installed, by direct electrolysis, the effects of the hydrogen potential and oxidation reduction potential characteristics attendant upon electric field change on a higher concentration oxidant generation characteristics were investigated. Consequently, as the third electrode was installed in the middle of two slit electrodes and the polarity of applied power was changed, it was observed that the third electrode system with the positive electrode can generate a higher concentration oxidant, hydrogen potential and oxidation reduction potential as compared with that of the negative electrode. It is because the positive electrode was bombarded mostly energetic electrons and the negative electrode was bombarded mainly by less energetic positive ions.

A Study on Electric Potential Change by Pulse Voltage Polarity in Liquid (펄스전압의 극성에 따른 액중 전위변화에 관한 연구)

  • Kim Jin-Gyu;Kim Hyung-Pyo;Park Young-Ho
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.4
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    • pp.79-84
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    • 2005
  • This paper proposes the new type of an ion exchange water generator system. The system has an +/- ion exchange membrane located in center and a diagonal-interdigit type electrode applied to a pulsed power. This system is studied in the liquid for the oxidation/reduction potential and the dissolved oxygen concentration by the polarity effects. Consequently, as a diagonal-interdigit type electrode is installed in each side of device, the oxidation/reduction potential and dissolved oxygen concentration by polarity changes and electrical resistivity differences be observed. An ion concentration in the ion exchange water generator system is increased by dissolved oxygen generated from oxidation/reduction potential changes.

New Application of Clay Filler for Carbon/Carbon Composites and Improvement of Filler Effect by Clay Size Reduction

  • Jeong, Eui-Gyung;Kim, Jin-Hoon;Lee, Young-Seak
    • Carbon letters
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    • v.11 no.4
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    • pp.293-297
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    • 2010
  • To investigate new potential application of a clay material for C/C composites, illite added C/C composites were prepared with various illite contents. The improvement of filler effect by illite size reduction was also investigated using wet ballmilling by evaluating illite/phenolic resin infiltration using bulk density and porosity measurements, chemical structural changes of the composites using XRD, and thermal oxidation stability in air of the composites using TGA. The size reduction of illite resulted in narrower particle size distribution and improved illite infiltration into carbon preform. And the resultant C/C composites prepared with illite had even more improved thermal oxidation stability in air, showing more increased IDTs up to $100^{\circ}C$, compared to those of the C/C composites with pristine illite, due to the SiC formation through carbothermal reduction between illite and carbon materials. The illite induced delay in oxidation of the illite-C/C composites was also observed and the delayed oxidation behavior was attributed to the layered structure of illite, which improved illite/phenol resin infiltration. Therefore, the potential use of illite as filler to improve oxidation stability of C/C composite can be promising. And the size reduction of illite can improve its effect on the desired properties of illite-C/C composites even more.

A Study on environmental-friendly Cleaning for Si-wafers (환경친화적인 실리콘 웨이퍼 세정 연구)

  • Yoon, Hyoseob;Ryoo, Kunkul
    • Clean Technology
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    • v.6 no.1
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    • pp.79-84
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    • 2000
  • In this study, to reduce the consumption of chemicals in cleaning processes, Si-wafers contaiminated with metallic impurities were cleaned with electrolyzed water(EW), which was generated by the electrolysis of a diluted electrolyte solution or ultra pure water(UPW). Electrolyzed water could be controlled for obtaining wide ranges of pH and ORP(oxidation-reduction potential). The pH and oxidation-reduction potential of anode water and cathode water were measured to be 4.7 and +1000mV, and 6.3 and -550mV, respectively. To analyze the amount of metallic impurities on Si-wafer surfaces, ICP-MS was introduced. Anode water was effective for Cu removal, while cathode water was more effective for Fe removal.

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Effect of Electrochemical Redox Reaction on Growth and Metabolism of Saccharomyces cerevisiae as an Environmental Factor

  • Na, Byung-Kwan;Hwang, Tae-Sik;Lee, Sung-Hun;Ahn, Dae-Hee;Park, Doo-Hyun
    • Journal of Microbiology and Biotechnology
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    • v.17 no.3
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    • pp.445-453
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    • 2007
  • The effect of an electrochemically generated oxidation-reduction potential and electric pulse on ethanol production and growth of Saccharomyces cerevisiae ATCC 26603 was experimented and compared with effects of electron mediators (neutral red, benzyl viologen, and thionine), chemical oxidants (hydrogen peroxide and hypochlorite), chemical reductants (sulfite and nitrite), oxygen, and hydrogen. The oxidation (anodic) and reduction (cathodic) potential and electric pulse activated ethanol production and growth, and changed the total soluble protein pattern of the test strain. Neutral red electrochemically reduced activated ethanol production and growth of the test strain, but benzyl viologen and thionine did not. Nitrite inhibited ethanol production but did not influence growth of the test strain. Hydrogen peroxide, hypochlorite, and sulfite did not influence ethanol production and growth of the test strain. Hydrogen and oxygen also did not influence the growth and ethanol production. It shows that the test strain may perceive electrochemically generated oxidation-reduction potential and electric pulse as an environmental factor.

The pH as a Control Parameter for Oxidation-Reduction Potential on the Denitrification by Ochrobactrum anthropi SY 509

  • Kim, Sung-Hong;Song, Seung-Hoon;Yoo, Young-Je
    • Journal of Microbiology and Biotechnology
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    • v.14 no.3
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    • pp.639-642
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    • 2004
  • The pH as a control parameter for oxidation-reduction potential (ORP) was investigated through the denitrification by Ochrobactrum anthropi SY509 under non-growing condition. The optimal pH of nitrate reductase was 7.0, and the minimal ORP level was -250 mV for the denitrification under aerobic condition. In the case of anaerobic condition, the optimal pHs of nitrate and nitrite reductase were shifted to 10.0 and 9.0, respectively, and the minimal ORP levels of nitrate and nitrite reductase were decreased to -370 mV and -340mV, respectively. In the case of alkaline pH and anaerobic condition, the denitrification efficiency of nitrate was increased up to about 2-fold over that of neutral pH and anaerobic condition. Therefore, the combined control of pH and ORP in the anaerobic condition is shown to be an important parameter in the biological denitrification process.

Nucleation Process of Indium on a Copper Electrode

  • Chung, Yonghwa;Lee, Chi-Woo
    • Journal of Electrochemical Science and Technology
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    • v.4 no.3
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    • pp.93-101
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    • 2013
  • The electrodeposition of indium onto a copper electrode from an aqueous sulfate solution containing $In^{3+}$ was studied by means of cyclic voltammetry and chronoamperometry. Reduction and oxidation of indium on copper were investigated by using cyclic voltammograms at different negative limiting potentials and at different scan rates in cumulative cycles. Cyclic voltammograms indicated that reduction and oxidation processes of indium could involve various reactions. Chronoamperometry was carried out to analyze the nucleation mechanism of indium in the early stage of indium electrodeposition. The non-dimensional plot of the current transients at different potentials showed that the shape of the plot depended on the applied potential. The nucleation of indium at potential step of -0.6~-0.8 V was close to progressive nucleation limited by diffusion. However the non-dimensional plot of current transients for the indium nucleation showed different behaviors from theoretical curves at the potential step lower than -0.8 V.

Effects of Organic Matter and pH on Chromium Oxidation Potential of Soil

  • Chung, Jong-Bae;Eum, Jin-Sup
    • Korean Journal of Environmental Agriculture
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    • v.20 no.5
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    • pp.346-351
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    • 2001
  • Oxidation of Cr(III) to Cr(VI) can increase availability and toxicity of chromium. In this study, possible mechanisms by which pH and organic matter can control the chromium oxidation and reduction in soil system were examined using four soils of different pHs and organic matter contents. Reduction of Mn-oxides occurred in the soils of higher organic matter content (4.0%), but Mn-oxide was quite stable during the incubation in the soil of pH 7.0 and 0.5% organic matter content. Manganese oxides can be reductively dissolved at lower pH and higher organic matter conditions. The soil of pH 7.0 and 4.0% organic matter content showed the highest Cr-oxidation potential. Reduction of soluble Cr(VI) was observed in all the soils examined. The most rapid reduction was found in soil of pH 5.5 and 4.0% organic matter content, but the reduction was slow in soil of pH 7.0 and 0.5% organic matter content. Thus, the reductive capacity of organic matter added soils was much higher as compared to other two soils of lower organic matter content. In all the soils examined, the reductive capacity of soluble chromium was much higher than the oxidative capacity. Organic matter was found to be the most important controlling factor in the chromium oxidation and reduction. Reduction of Cr(VI) to Cr(III) could be a potentially useful remediation or detoxification process, and availability and toxicity of chromium in soil would be controlled by controlling organic matter content and pH of the soils.

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