• Journal of Microbiology and Biotechnology
• /
• v.15 no.5
• /
• pp.1080-1086
• /
• 2005

Membranes prepared from Vibrio natriegens oxidized both NADH and deamino-NADH as substrates. The maximum activity of the membrane-bound NADH oxidase was obtained at about pH 8.5 in the presence of 0.2 M NaCl, whereas that of the NADH:ubiquinone oxidoreductase was obtained at about pH 7.5 in the presence of 0.2 M NaCl. Electron transfer from NADH or deamino-NADH to ubiquinone-l or oxygen generated a considerable membrane potential (${\Delta}{\psi}$), which occurred even in the presence of $20{\mu}M$ carbonylcyanide m-chlorophenylhydrazone (CCCP). However, the ${\Delta}{\psi}$ was completely collapsed by the combined addition of $10{\mu}M$ CCCP and $20{\mu}M$ monensin. On the other hand, the activity of the NADH oxidase and the ${\Delta}{\psi}$ generated by the NADH oxidase system were inhibited by about $90\%$ with $10{\mu}M$ HQNO, whereas the activity of the NADH:ubiquinone oxidoreductase and the ${\Delta}{\psi}$ generated at the NADH:ubiquinone oxidoreductase segment were inhibited by about $60\%$. Interestingly, the activity of the NADH:ubiquinone oxidoreductase and the ${\Delta}{\psi}$ generated at the NADH:ubiquinone oxidoreductase segment were resistant to the respiratory chain inhibitors such as rotenone, capsaicin, and $AgNO_3$, and the activity of the NADH oxidase and the ${\Delta}{\psi}$ generated by the NADH oxidase system were very sensitive only to $AgNO_3$. It was concluded, therefore, that V. natriegens cells possess a $AgNO_3$-resistant respiratory $Na^+$ pump that is different from the $AgNO_3$-sensitive respiratory $Na^+$ pump of a marine bacterium, Vibrio alginolyticus.

• Journal of the Korean Applied Science and Technology
• /
• v.29 no.3
• /
• pp.421-428
• /
• 2012

We investigated an electrochemical properties for Langmuir-Blodgett (LB) nano-films of polyimide and phospholipid mixture. LB films of polyamic acid and phospholipid monolayer were deposited by the Langmuir-Blodgett method on the indium tin oxide(ITO) glass. The electrochemical properties measured by cyclic voltammetry with three-electrode system(an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode) in $KClO_4$ solution. The current of reduction and oxidation range was measured from 1650 mV to -1350 mV, continuously. The scan rates were 50, 100, 150, 200 and 250 mV/s, respectively. As a result, monolayer LB films of polyamic acid and phospholipid mixture was appeared on irreversible process caused by the reduction current from the cyclic voltammogram. Diffusion coefficient (D) effect in the polyamic acid and phospholipid mixture was used in the LAPC with LLPC fewer than the diffusion coefficient values.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.2
• /
• pp.210-220
• /
• 2013

Recently, as we move toward a society with an increasingly aged population, wearable U-health devices in various shapes with smart wear have been developed in order to conveniently measure health variables without using hands in daily life or at home. However, the problem is that only supply of the wearable U-health devices is focused and its applicable devices are studied and developed, which has resulted in lack of awareness of importance of performance evaluation. In this study, two electrodes were fabricated using conductive fabric which can be used as electrode if attached to wearable U-health devices or smart wear in order to measure ECG signal. Two electrodes those were fabricated using conductive fabric were compared the correlation, impedance and CMRR with patch typed Ag-AgCl electrode-normally used for measurement of ECG signal, so that the study would find out if the fabricated electrode can be used with the wearable U-health devices by testing and evaluating performances.

• Proceedings of the KIEE Conference
• /
• 2004.07d
• /
• pp.2696-2698
• /
• 2004

Iontophoresis를 이용한 경피전달용 약물 패치를 제작하기 위해 고분자의 종류, 전류크기, 시간에 따른 약물방출 결과를 발표한다. 고분자 Hydroxy Propyl Methyl Cellulose(HPMC), Hydroxy Propyl Cellulose(HPC), Hydroxy Ethyl Cellulose(HEC)에 각각 국소마취제-Lidocaine을 넣어 시료를 제작하였다. 약물 방출은 Drug Delivery Cell(DDC)위에 Ag/AgCl 전극 (anode), Pt wire 전극(cathode)을 각각 설치하여 전압인가에 따른 이온 유동으로부터 시간에 따른 전압/전류변화 및 약물농도를 고찰하였다. 전압 15V 인가 시 고분자 막과 전해질 사이에 흐르는 전류 1.0mA는 15분간 유지되지만, Ag/AgCl 전극의 산화작용으로 인해 전류는 서서히 감소하며 26분 후 거의 흐르지 않았다. 따라서 안정적인 전류로 유지되는 시간을 15분으로 최적화하였다. 고분자 중 HPMC 막을 사용하여 약물방출 실험을 한 경우 UV 분석결과 파장 262.26nm에서 최대 흡광도 0.238이었고, 가장 높은 약물농도가 나타났다. 이러한 HPMC의 약물방출 실험결과 비교적 높은 전류 1.0mA일 때 약물 방출량이 많았고, 동일한 전류 0.4mA를 장시간 흐르게 하였을 경우, 농도가 축적되므로 치료 가능한 안정적인 특성임을 확인하였다.

• Journal of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.707-712
• /
• 1991

N'-phenyl-N-(2-chloroethyl)-N-aminourea has been prepared from N'-phenyl-N-(2-chloroethyl)-N-nitrosourea by means of the electrochemical reduction with the mercury pool electrolytic cell. In order to find out the optimum condition of the reaction, the voltammetric behaviors for N'-aryl-N-(2-chloroethyl)-N-nitrosourea derivatives have been investigated by the cyclic voltammetry and polarography. The peak potentials was shifted to the negative direction as the pH value of the solution decrease. The substituent effects of phenyl ring on the peak potential were not observed in this case. (5:3) EtOH/4 N-HCl mixed solution was employed for the electrolysis. The applied potential was -0.7 V vs. Ag/AgCl/4 N-HCl electrode. The number of electrons participated to the reduction process was 4, respectively. The product was identified by FT-IR, NMR, mass and/or elemental analysis data.

• Journal of the Korean Chemical Society
• /
• v.45 no.4
• /
• pp.298-303
• /
• 2001

The trace-level mercury in bio-materials has been determinated by the anodic stripping square wave voltammetry (ASSWV)-technique at glassy carbon electrode. Prior to the analysis, the bio-materials were digested with $HNO_3/H_2SO_4$ mixture and KMnO4 was added to complete an oxidation process of the mixture. The detection limit of the mercury varied greatly with deposition time, deposition potential, pH and stirring rate. When the deposition was carried out for 240 sec on 400 rpm stirring at -1.0 volts vs. Ag/AgCl, the detection limit was below 0.5 ppb ($2.5{\times}10^{-9}M$). The accumulated mercury was high in the kidney and liver, and low in the brain according to the determination of mercury accumulation for a white rat by this method.

• Journal of the Korean Chemical Society
• /
• v.37 no.11
• /
• pp.937-942
• /
• 1993

Enzyme electrodes for amperometric measurement of ammonia was prepared by immobilization of L-glutamate dehydrogenase on an Immobilon-AV Affinity membrane and attachment to a glassy carbon electrode. Reduced nicotinamide adenine dinucleotide (NADH) was used as the electroactive species. The electrochemical oxidation of NADH was monitored at ＋1.0 volt vs. Ag/AgCl. Response was linear from $4.0\;{\times}\;10^{-5}\;to\;4.0\;{\times}\;10^{-4}$ M. The detection limit was 2.0 ${\times}\;10^{-6}$ M. Response time, the optimum pH and life time of enzyme immobilized membrane were 2 min, pH 7.3∼7.6 (Dulbecco's buffer solution) and about 25 days respectively. When the enzyme electrode was applied to the $NH_4^+$ determination with amperometric method, other physiological materials had no interference.

• Journal of the Korean Chemical Society
• /
• v.48 no.5
• /
• pp.491-498
• /
• 2004

The response characteristics of the bioelectrode developed by the co-immobilization of black goat liver tissue and ferrocene in a carbon paste matrix for the amperometric determination of hydrogen peroxide were evaluated. In the range of electrode potential examined ($-0.3{\sim}+0.0\;V$ vs. Ag/AgCl), the response time was relatively short (t95%=12 s) and it responded in the wide range of pH. The detection limit was 2.25${\times)10^{-6}M$ and a relative standard deviation of the measurements which were repeated 15 times using 1.0${\times}10^{-2 }$M hydrogen peroxide was 1.87%. The bioelectrode sensitivity decreased to 50% of the original value in 19 days of continuous use.

• Applied Chemistry for Engineering
• /
• v.8 no.2
• /
• pp.161-171
• /
• 1997

Anodic regeneration of PCB enchant and cathodic deposition of copper using electrochemical method has been studied. Cu(I)/Cu(II) concentration ratio as a function of Cu(I) oxidation at the anode was measured from the potential difference between platinum and Ag/AgCl/4M KCl electrodes. Chlorine gas evolution was minimized by maintaining Cu(I) concentration above a specific concentration and using non-porous graphite electrode. Dendritic copper deposition was observed at the cathode and the optimum conditions for Cu deposition was identified as the current density of $360mA/cm^2$, and copper concentration of 12 g/l. Titanium was the most effective cathode material which showed a higher current efficiency and copper recovery. The current efficiency decreased with increasing temperature, but the highest power efficiency was achieved at $50^{\circ}C$.

• Analytical Science and Technology
• /
• v.8 no.3
• /
• pp.285-292
• /
• 1995

Uranium has variable oxidation states(${UO_2}^{+2}$, $UO^{+2}$, $U^{+4}$, $U^{+3}$) and 1-(2-Pyridylazo)-2-naphthol forms a very stable chelate with Uranium(${UO_2}^{+2}$). The determination method of Uranium(${UO_2}^{+2}$) in 0.1M Borate buffer(pH 7.10) has been investigated by adsorptive stripping voltammetry. The optimum conditions were PAN concentration of $5{\times}10^{-7}M$, accumulation potential of 0.00V(vs. Ag/AgCl) and accumulation time of 120sec. The calibration curve was linear over the range of $5{\sim}60{\mu}g/L$ and the various metal ions did not interfere with the determination Uranium(${UO_2}^{+2}$) except Cu(II) and Co(II).