• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.709-719
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• 1992

We synthesized the binuclear tetradentate Schiff base cobalt(II), nickel(II) and copper(II) complexes such as [Co(II)_2(TSBP)(L)_4], [Ni(II)_2(TSBP)(II)_4] and [Cu(II)_2(TSBP)] (TSBP: 3,3',4,4'-tetra(salicylideneimino)-1,1'-biphenyl, L: Py, DMSO and DMF). We identified the binucleated structure of these complexes by elemental analysis, IR-spectrum, UV-visible spectrum, T.G.A. and D.S.C. According to the results for cyclic voltammogram and differential pulse polarogram of 1 mM complexes in nonaqueous solvents included 0.1M TEAP-L (L; Py, DMSO and DMF) as supporting electrolyte, it was found that diffusionally controlled redox processes of four steps through with one electron for binucleated Schiff base Cobalt(II) complex was Co(III)_2 {^\longrightarrow \\_\longleftarrow^e^-}Co(III)Co(II)_2{^\longrightarrow \\_\longleftarrow^e^-}Co(II){^\longrightarrow \\_\longleftarrow^e^-}Co(I){^\longrightarrow \\_\longleftarrow^e^-}Co(I)_2 and two steps with one electron for Nickel(II) and Copper(II) complexes were M(II)_2 {^\longrightarrow \\_\longleftarrow^e^-}M(I)M(I){^\longrightarrow \\_\longleftarrow^e^-}M(I)_2 (M; Ni and Cu) in nonaqueous solvents.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.8
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• pp.3451-3455
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• 2014

Background: The serum carcinoembryonic antigen (CEA) level can reflect tumor growth, recurrence and metastasis. It has been reported that epidermal growth factor receptor (EGFR) mutations in exons 19 and 21may have an important relationship with tumor cell sensitivity to EGFR-TKI therapy. In this study, we investigated the clinical value of EGFR mutations and serum CEA in patients with non-small cell lung cancer (NSCLC). Materials and Methods: The presence of mutations in EGFR exons 19 and 21 in the tissue samples of 315 patients with NSCLC was detected with real-time fluorescent PCR technology, while the serum CEA level in cases who had not yet undergone surgery, radiotherapy, chemotherapy and targeted therapy were assessed by electrochemical luminescence. Results: The mutation rates in EGFR exons 19 and 21 were 23.2% and 14.9%, respectively, with the two combined in 3.81%. Measured prior to the start of surgery, radiotherapy, chemotherapy and targeted treatment, serum CEA levels were abnormally high in 54.3% of the patients. In those with a serum CEA level <5 ng/mL, the EGFR mutation rate was 18.8%, while with 5~19 ng/mL and ${\geq}20ng/mL$, the rates were 36.4% and 62.5%. In addition, in the cohort of patients with the CEA level being 20~49 ng/mL, the EGFR mutation rate was 85.7%, while in those with the CEA level ${\geq}50ng/mL$, the EGFR mutation rate was only 20.0%, approximately the same as in cases with the CEA level<5 ng/mL. Conclusions: There is a positive correlation between serum CEA expression level and EGFR mutation status in NSCLC patients, namely the EGFR mutation-positive rate increases as the serum CEA expression level rises within a certain range (${\geq}20ng/mL$, especially 20~49 ng/mL). If patient samples are not suitable for EGFR mutation testing, or cannot be obtained at all, testing serum CEA levels might be a simple and easy screening method. Hence, for the NSCLC patients with high serum CEA level (${\geq}20ng/mL$, especially 20~49 ng/mL), it is worthy of attempting EGFR-TKI treatment, which may achieve better clinical efficacy and quality of life.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.230-237
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• 2017

In this study, electrochemical methods were used to determine the optimum protection potential of S355ML steel for the cathodic protection of offshore wind-turbine-tower substructures. The results of potentiodynamic polarization experiments indicated that the anodic polarization curve did not represent a passivation behavior, while under the cathodic polarization concentration, polarization was observed due to the reduction of dissolved oxygen, followed by activation polarization by hydrogen evolution as the potential shifted towards the active direction. The concentration polarization region was found to be located between approximately -0.72 V and -1.0 V, and this potential range is considered to be the potential range for cathodic protection using the impressed current cathodic protection method. The results of the potentiostatic experiments at various potentials revealed that varying current density tended to become stable with time. Surface characterization after the potentiostatic experiment for 1200 s, by using a scanning electron microscope and a 3D analysis microscope confirmed that corrosion damage occurred as a result of anodic dissolution under an anodic polarization potential range of 0 to -0.50 V, which corresponds to anodic polarization. Under potentials corresponding to cathodic polarization, however, a relatively intact surface was observed with the formation of calcareous deposits. As a result, the potential range between -0.8 V and -1.0 V, which corresponds to the concentration polarization region, was determined to be the optimum potential region for impressed current cathodic protection of S355ML steel.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.700-708
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• 2013

Pyroprocessing has been developed for the purpose of resolving the current spent nuclear fuel management issue and enhancing the recycle of valuable resources. Pyroprocessing has been developed with the dry technologies which are performed under high temperature conditions excluding any aqueous processes. Pyro-processes which are based on the electrochemical principles require pretreatment processes and a voloxidation process is considered as a pretreatment step for an electrolytic reduction process. Various kinds of gas conditions are applicable to the voloxidation process and the understanding of Cs behavior during the process is of importance for the analyses of waste characteristics and heat load on the overall pyroprocessing. In this study, the changes of chemical compounds with the gas conditions were calculated by analyzing gas-solid reaction behavior based on the chemical equilibria on a Cs-Te-O system. $Cs_2TeO_3$ and $Cs_2TeO_4$ were selected after a Tpp diagram analysis and it was confirmed that they are relatively stable under oxidizing atmospheres while it was shown that Cs and Te would be removed by volatilization under reducing atmosphere at a high temperature. This work provided basic data for predicting Cs behavior during the voloxidation process at which compounds are chemically distributed as the first stage in the pyroprocessing and it is expected that the results would be used for setting up material balances and related purposes.

• Journal of Conservation Science
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• v.30 no.1
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• pp.95-101
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• 2014

Silver objects tarnish with black from reaction with sulfurous acid or hydrogen sulfide of atmospheric. Blackening of silver objects results from formation of silver sulfide($Ag_2O$) on the surface. Silver sulfide usually is usually removed by conservation treatment. There are several cleaning methods such as chemical, electrochemical and micro-abrasion cleaning, but all of them consume silver. This study investigated the safe and effective parameter of laser cleaning by test on silver coupons. Laser cleaning is a selective process for the removal of specific substances. At first, laser cleaning applied to plain silver coupons, which were not corroded, to find out the safe range of laser energy density. From results, plain silver coupons were not changed at 1064nm below $4.00J/cm^2$ and at 532nm below $2.39J/cm^2$. The corrosion layer(silver sulfide) of artifical corroded silver coupons was removed at 1064nm with $2.39J/cm^2$ by 5~10 pulses and at 532nm with $1.19J/cm^2$ by 5~10 pulses. The removal thickness of corrosion layer was about 13-25nm per a laser pulse using AES analysis. In addition, laser cleaning tested the tarnish silver rings based on the results of silver coupons. As a result of test, the black surface were clean successfully and gave luster of silver, which showed the application possibility of laser cleaning for silver objects.

• Analytical Science and Technology
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• v.5 no.3
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• pp.239-247
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• 1992

The complexations and selectivities of the 10 species of mono- and dimethylsubstituted anilinium ions with 18-crown-6 in methanol are examined at dropping mercury electrode. The stability constants of these complexes varies drastically due to the steric hindrance by the positions and numbers of methyl groups. And the analyses of the isomeric mixtures of methylanilinium, which are impossible to detect due to the overlapped peaks in normal conditions, were also accomplished by the additions of 18-crown-6 as the supporting complexing agent using the selective complexations by the steric hindrance effects. As results in case of the difference of stability, ${\Delta}log\;K$ were about 0.7~1.3, it was possible to confirm the existence of two species qualitatively. Otherwise when ${\Delta}log\;K$ were large than 1.6, the quantitative determinations of each species could be accomplished sucessfully. From these results it is deduced that the selective recongnition of the positions and numbers of methyl groups as the steric hindrance in anililniums by 18-crown-6 cause the large variation of the magnitudes of negative shift of reduction waves for guest ions in mixtures.

• Journal of Sensor Science and Technology
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• v.10 no.2
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• pp.125-133
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• 2001

Conducting polymer sensors show high sensitivity when exposed to volatile organic compounds gases at room temperature. The 8 sensor array using by polypyrrole and polyaniline has been fabricated by chemical polymerization for measuring sensing characteristics of VOCs gases. Conducting polymer was polymerized by using distilled pyrrole, aniline as a monomer and ammonium persulfate (APS) as an oxidant and dodecylbenzene sulfonic acid (DBSA) as a dopant. Dedoped film was synthesized by reverse voltage and redoped film was synthesized by using 1-octanesulfonic acid sodium salt as another dopant in electrochemical cell. The sensitivity and reversibility were influenced by doping, dedoping, redoping and thickness for the polypyrrole and polyaniline. We investigated the relation between the structure of conducting polymer and sensitivity of these sensors through the analysis of scanning electron microscope (SEM), scanning probe microscope (SPM) and $\alpha$-step.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.46-52
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• 2006

The effects of surface treatment on the hydrogen storage properties of a $Mg_2Ni$ alloy particle were investigated by the microvoltammetric technique, in which a carbon-filament microelectrode was manipulated to make electrical contact with the particle in a KOH aqueous solution. It was found that the hydrogen storage properties of $Mg_2Ni$ at room temperature were improved by the surface treatment with a nickel plating solution. The sodium salts(sodium phosphate and sodium dihydrogen citrate) contained in the nickel plating solution made the alloy form an amorphous-like state, resulting in an improved hydrogen charge/discharge capacity at room temperature as high as about 150[mAh/g] from the original value of 17[mAh/g]. Potential-step experiment was carried out to determine the apparent chemical diffusion coefficient of hydrogen atom($D_{app}$) in the alloy. Since the alloy particle we used here was a dense, conductive sphere, the spherical diffusion model was employed for data analysis. $D_{app}$ was found to vary the order between $10^{-8}{\sim}10^{-9}[cm^2/s]$ over the course of hydrogenation and dehydrogenation process.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.729-734
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• 2002

In this study, the polyaniline films of emeraldine base(EB) and lucoemeraldine base(LEB) form chemically doping with poly(sodium-4 styrenesulfonate, PSS) were prepared by casting the mixed solution of chloroform and m-cresol on ITO(indium tin oxide) electrode. By analyzing UV-vis spectra of the mixed solutions, the effects of the secondary doping by m-cresol were obtained. And the conductivity of polyaniline film was increased with increasing m-cresol content. The results suggest that the improvement of conductivity obtained by secondary doping results primarily from interaction of polyaniline and m-cresol. As the results of analyzing cyclic voltammograms, it was known that the redox peak currents of polyaniline electrode prepared from LEB were larger and more reversible than those of polyaniline electrodes prepared from EB. The charge transfer resistances($R_{ct}$) of polyaniline electrodes were reduced with increasing m-cresol content, and LEB/PSS electrodes were smaller than EB/PSS electrodes. This result agrees to the analysis of the redox peak current of cyclic voltammograms. The solution resistance and the capacity of electrical double layer almost unchanged in all prepared polyaniline electrodes. It was confirmed that solution resistance was independent of frequency factor in AC impedance spectra. Also the polyaniline film doping with PSS was revealed pseudo n-type characteristics of conducting polymer.

• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.295-303
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• 1989

Tetradentate Schiff base cobalt(II) complex; Co(SND) and Co(SOPD) were synthesized, and these complexes were allowed to react with dry oxygen to form oxygen adducts cobalt(III) complexes such as $[Co(SND)(Py)]_2O_2$ and $[Co(SOPD)(Py)]_2O_2$ in pyridine. These complexes have been identified by IR specta, T.G.A., magnetic susceptibilities measurements and elemental analysis. It has been found that the oxygen adducts coblat(III) complexes have hexacoordinated octahedral configuration with tetradentate Schiff base cobalt(II), pyridine and oxygen, and the mole ratio of oxygen to cobalt(II) complexes are 1;2. The redox reaction processes of $Co(SND)(Py)_2$ and $Co(SOPD)(Py)_2$ complexes were investigated by cyclic voltammetry with glassy carbon electrode in 0.1M TEAP pyridine. The result of redox reaction processes of Co(III)/Co(II) and Co(II)/Co(I) for $Co(SND)(Py)_2$ and $Co(SOPD)(Py)_2$ complexes are reversible or quasi reversible process but oxygen adducts complexes are irreversible processes. Redox process for oxygen of oxygen adducts complexes was quasi reversible and redox range of potential was $E_{pc}\;=\;-0.96{\sim}-1.03V$ and $E_{pa}\;=\;-0.78{\sim}-0.80V.$