• Analytical Science and Technology
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• v.17 no.5
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• pp.438-442
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• 2004

To determine the contents of $^{99}Tc$ in the spent PWR (pressurized water reactor) nuclear fuels by ICP-MS (inductively coupled plasma-mass spectrometry), a technetium separation method using an extraction chromatographic resin (TEVA Spec resin) has been established. $^{99}Tc$ was separated from a spent PWR nuclear fuel solution by this separation procedure and its concentration was determined by ICP-MS. The result agrees well with the value calculated by the program ORIGEN 2 and also the value measured by AG MP-1 resin/ICP-MS method described in our previous paper. It can be concluded that the present separation procedure is superior to the AG MP-1 resin procedure with respect to the time required for technetium separation as well as the efficiency of decontamination from other radioactive nuclides.

• Analytical Science and Technology
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• v.11 no.5
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• pp.400-403
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• 1998

The germanium content of the cultivated Korean medicinal herbs in several growing district was determined by adsorption stripping voltammetry. The optimum conditions in germanium determination were as following: deposition time; 120 sec, deposition potential; -0.9 volts vs. Ag/AgCl, and frequency; 100 Hz in $5.0{\times}10^{-2}M$ perchloric acid supporting electrolyte solution containing $8.0{\times}10^{-2}M$ catechol. Calibration curve was shown a good lineality in the range of 0.4 ppb to 2.0 ppm and the detection limit was 0.08 ppb. There was a large difference in content of the cultivated hermit leaf according to growing district such as 29.7~385.7 ppm and the content of nontreated hermit leaf was higher than the processed health foodstuffs. The content of the Korean ginseng (5 years) was 83 ppm while the Korean herb of life was 214 ppm.

• Journal of the Korean Applied Science and Technology
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• v.26 no.4
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• pp.451-456
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• 2009

We carried out this experiment to observe an electrochemical properties for LB films of alkyl compounds by the cyclic voltammetry. Alkyl bromides was deposited by using the Langmuir- Blodgett method on the ITO glass. We measured to an electrochemical measurement by using cyclic voltammetry with a three-electrode system(an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode) in 0.5, 1.0, 1.5 and 2.0 N $NaClO_4$ solution. A measuring range was reduced from initial potential to -1350 mV, continuously oxidized to 1650 mV. The scan rate were 100 mV/s. As a result, an electrochemical properties of the LB films of alkyl bromides appeared irreversible process caused by only the oxidation current from the cyclic voltammogram. The diffusivity(D) effect of LB films decreased with increasing of alkyl compounds amount.

• Journal of the Korean Applied Science and Technology
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• v.26 no.4
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• pp.400-406
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• 2009

We investigated the electrochemical properties for Langmuir-Blodgett (LB) films of functionalized polyimide. LB films of polyimide monolayer were deposited by the Langmuir-Blodgett method on the indium tin oxide(ITO) glass. The electrochemical properties measured by cyclic voltammetry with a three-electrode system(an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode) at various concentrations(0.5, 1.0, and 1.5 N) of $NaClO_4$ solution. The current of reduction and oxidation range was measured from 1650 mV to -1350 mV, continuously. The scan rates were 50, 100 and 150 mV/s, respectively. As a result, monolayer and multilayer LB films of polyimide are appeared on irreversible process caused by the oxidation current from the cyclic voltammogram.

• Journal of the Korean Applied Science and Technology
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• v.19 no.1
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• pp.49-55
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• 2002

We carried out this experiment to observe electrochemical properties for LB films of phospholipid(Dilauroyl-L-${\alpha}$-Phosphayidylcholine) and 4-octyl-4'-(5-carboxypentamethylene-oxy)azobenzene mixture by the cyclic voltammetry. LB films of 8A5H and 8A5H-DLPC(1:1, 2:1) were deposited by using the Langmuir-Blodgett method on the ITO glass. We determined electrochemical measurement by using cyclic voltammetry with a three-electrode system, An Ag/AgCl reference elect rode, a platinum wire counter electrode and LB film-coated ITO working electrode measured in 0.1, 0.5, and 1.0 mol/L $NaClO_{4}$ solution. A measuring range was reduced from initial potential to -1350 mV, continuously oxidized to 1650 mV and measured to the initial point. The scan rate were 50, 100, 150 and 200 mV/s. As a result, LB films of 8A5H 8A5H-DLPC appeared irreversible process caused by only the oxidation current from the cyclic voltammogram.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.6
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• pp.520-525
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• 2000

Glucose oxidase was immobilized in polypyrrole by electrosynthesis. The enzyme had an influence on the redox properties of a complex enzyme electrode. In the cyclic voltammograms of the enazyme electrode new peaks were appeared at the potential around 0.7V vs. Ag/AgCl in additional to the typical peaks for polypyrrole. The more immobilized the stronger the peaks became. During the cycling the pH of electrolyte solution was decreased to about 4.4 The reason for that is to be the proton released from the carboxyl in the glucose oxidase in order to keep on a charge neutrality of the oxidized enzyme. This fact suggests that the new peaks in the voltammograms are caused by the redox of glucose oxidase. In the AC impedance spectrum analysis of the electrode the diffusion of electrolyte anion was limited because of chained structure of the enzyme. The faradic impedance was large since the glucose oxidase is an insulator. Therefore when glucose oxidase is entrapped the enzyme should be limited in amount. Because the growth of the polypyrrole is accompanied both charge transfer and mass transport. For the traditional electrosynthesis that means amount of enzyme present in the electrode is limited to as much as film growable.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2271-2278
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• 2007

Electron transfer of a redox protein at a bare gold electrode is too slow to observe the redox peaks. A novel Nafion-riboflavin functional membrane was constructed during this study and electron transfer of cytochrome c, superoxide dismutase, and hemoglobin were carried out on the functional membrane-modified gold electrode with good stability and repeatability. The immobilized protein-modified electrodes showed quasireversible electrochemical redox behaviors with formal potentials of 0.150, 0.175, and 0.202 V versus Ag/AgCl for the cytochrome c, superoxide dismutase and hemoglobin, respectively. Whole experiment was carried out in the 50 mM MOPS buffer solution with pH 6.0 at 25 oC. For the immobilized protein, the cathodic transfer coefficients were 0.67, 0.68 and 0.67 and electron transfer-rate constants were evaluated to be 2.25, 2.23 and 2.5 s?1, respectively. Hydrogen peroxide concentration was measured by the peroxidase activity of hemoglobin and our experiment revealed that the enzyme was fully functional while immobilized on the Nafion-riboflavin membrane.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1983-1987
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• 2008

This study demonstrates the electrochemical conversion of the synthetic procedure of monolayer-protected clusters using a thin toluene layer over an edge plane pyrolytic graphite electrode. A thin toluene layer with a thickness of 0.31 mm was coated over the electrode and an immiscible liquid/liquid water/toluene interface was introduced. The transfer of the tetrachloroaurate ($AuCl_4^-$) ions into the toluene layer interposed between the aqueous solution and the electrode surface was electrochemically monitored. The $AuCl_4^-$ ions initially could not move through into the toluene layer, showing no reduction wave, but, in the presence of the phase transfer reagent, tetraoctylammonium bromide (TOABr), a cathodic wave at 0.23 V vs. Ag/AgCl was observed, indicating the reduction of the transferred $AuCl_4^-$ ions in the toluene layer. In the presence of dodecanethiol together with TOABr, a self-assembled monolayer was formed over the electro-deposited metallic gold surface. The E-SEM image of the surface indicates the formation of a highly porous metallic gold surface, rather than individual nanoparticles, over the EPG electrode.

• Corrosion Science and Technology
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• v.6 no.6
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• pp.304-307
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• 2007

As to the reflection electrode of LCD (liquid crystal displays), silver-copper-gold alloy (hereafter, it is called as ACA (Ag98%, Cu1%, Au1%)) is an effective material of which weathering resistance can be improved more compared with pure silver. However, there is a problem that gold remains on the substrate as residues when ACA is etched in cerium ammonium nitrate solution or phosphoric acid. Gold can not be etched in these etchants as readily as the other two alloying elements. Gold residue has actually been removed physically by brushing etc. This procedure causes damage to the display elements. Another etchant of iodine/potassium iodide generally known as one of the gold etchants can not give precise etch pattern because of remarkable difference in etching rates among silver, copper and gold. The purpose of this research is to obtain a practical etchant for ACA alloy. The results are as follows. The cyanogen complex salt of gold generates when cyanide is used as the etchant, in which gold dissolves considerably. Oxygen reduction is important as the cathodic reaction in the dissolution of gold. A new etchant of sodium cyanide / potassium ferricyanide whose cathodic reduction is stronger than oxygen, can give precise etch patterns in ACA alloy swiftly at room temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.874-877
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• 2004

We carried out this subject to observe electrochemical properties of 1,2-dioleoyl-sn- glycero-3-phosphocholine(DOPC) mixed with fatty acid containing azobenzene group by using cyclic voltammetry with a three-electrode system, An Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode in $NaClO_4$ solution. We investigated the photoisomerization and electrochemical property of the organic ultra thin film of fatty acid containing azobenzene was prepared on the hydrophilic ITO(idium tin oxide) glass plate by LB method. As a result, the absorption spectra of BASH and DOPC of mixture LB films was induced to photoisomerization by alternating irradiation of ultraviolet and visible light. A measuring range was reduced from initial potential to -1350mV, continuously oxidized to 1650 mV and measured to the initial point. The scan rate were 50, 100, 150 and 200 mV/s. As a results, LB films of BASH-DMPC appeared reversible process caused by the reduction-oxidation current from the cyclic voltammogram.