• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.720-725
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• 2012

Sodium hypochlorite is used worldwide as a water disinfectant and in bleaching agent. Sodium hypochlorite applied to water initially undergoes hydrolysis to form free chlorine consisting of hypochlorous acid(HOCl) and hypochlorite ion($OCl^-$). For free chlorine determination, an electrochemical method is simple due to the electroactivity of free chlorine; it measures current and is free of most reagents. Amperometric free chlorine sensor has been developed with gold (Au)-based electrode. The 3-electrode free chlorine sensor whose working and counter electrodes were Pt exhibited excellent response to HClO at +400mV vs. Ag/AgCl/sat. KCl. In addition, the use of a pH error correction algorithm provided a reliable measurement of residual free chlorine in water sample without any pretreatment in the normal pH range(pH 6~8) of municipal water supply. The free chlorine sensor installed in on-line monitoring system could be used to continually monitor the level of residual free chlorine in real samples.

• Carbon letters
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• v.13 no.4
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• pp.254-259
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• 2012

Nanoporous non-woven carbon fibers for a gas sensor were prepared from a pitch/polyacrylonitrile (PAN) mixed solution through an electrospinning process and their gas-sensing properties were investigated. In order to create nanoscale pores, magnesium oxide (MgO) powders were added as a pore-forming agent during the mixing of these carbon precursors. The prepared nanoporous carbon fibers derived from the MgO pore-forming agent were characterized by scanning electron microscopy (SEM), $N_2$-adsorption isotherms, and a gas-sensing analysis. The SEM images showed that the MgO powders affected the viscosity of the pitch/PAN solution, which led to the production of beaded fibers. The specific surface area of carbon fibers increased from 2.0 to $763.2m^2/g$ when using this method. The template method therefore improved the porous structure, which allows for more efficient gas adsorption. The sensing ability and the response time for the NO gas adsorption were improved by the increased surface area and micropore fraction. In conclusion, the carbon fibers with high micropore fractions created through the use of MgO as a pore-forming agent exhibited improved NO gas sensitivity.

• Carbon letters
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• v.14 no.3
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• pp.186-189
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• 2013

We report a highly sensitive $NO_2$ gas sensor based on multi-layer graphene (MLG) films synthesized by a chemical vapor deposition method on a microheater-embedded flexible substrate. The MLG could detect low-concentration $NO_2$ even at sub-ppm (<200 ppb) levels. It also exhibited a high resistance change of ~6% when it was exposed to 1 ppm $NO_2$ gas at room temperature for 1 min. The exceptionally high sensitivity could be attributed to the large number of $NO_2$ molecule adsorption sites on the MLG due to its a large surface area and various defect-sites, and to the high mobility of carriers transferred between the MLG films and the adsorbed gas molecules. Although desorption of the $NO_2$ molecules was slow, it could be enhanced by an additional annealing process using an embedded Au microheater. The outstanding mechanical flexibility of the graphene film ensures the stable sensing response of the device under extreme bending stress. Our large-scale and easily reproducible MLG films can provide a proof-of-concept for future flexible $NO_2$ gas sensor devices.

• Journal of Electrochemical Science and Technology
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• v.9 no.3
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• pp.169-175
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• 2018

Cu-Salen complex was prepared and attached into chitosan (Cs) polymer backbone. Nanocomposite of the synthesized polymer was prepared with functionalized carbon nano-particles (Cs-Cu-sal/C) to modify the electrode surface. The surface morphology of (Cs-Cu-sal/C) nanocomposite film showed a homogeneous distribution of carbon nanoparticles within the polymeric matrix. The cyclic voltammogram of the modified electrode exhibited a redox behavior at -0.1 V vs. Ag/AgCl (3 M KCl) in 0.1 M PB (pH 7) and showed an excellent hydrogen peroxide reduction activity. The Cs-Cu-sal/C electrode displays a linear response from $5{\times}10^{-6}$ to $5{\times}10^{-4}M$, with a correlation coefficient of 0.993 and detection limit of $0.9{\mu}M$ (at S/N = 3). The sensitivity of the electrode was found to be $0.356{\mu}A\;{\mu}M^{-1}\;cm^{-2}$.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.261-264
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• 2002

CHO (Chinese hamster ovary) cells were transfected with plasmids containing both cis-acting HRE (hypoxia response element) and CMV-promoter that controls tissue-type plasminogen activator (t-PA). CHO cells with HRE produced 16.2 fold higher t-PA concentration than CHO cells without HRE. It was noted that hypoxia strongly induced CHO cell apoptosis. which resulted in decrease of cell viability and protein production. In this study. by introducing Bcl-2, anti-apoptotic gene, we tried to recover cell viability and increase the protein production. When batch culture of both control cells without transfection of Bcl-2 and cells transfected with Bcl-2 were performed in the absence of CoCl ι hypoxia mimic condition. the cells with Bcl-2 were effected specific cell growth rates, maximum cell density. Immunoblotting assay showed Bcl-2 was recombinant with HRE dependent t- P A expression cassette, and their expression level was depended on hypoxia. By introducing Bcl-2, both cell viability and maximum cell density could be increased.

• Biomolecules & Therapeutics
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• v.4 no.4
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• pp.354-363
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• 1996

This study was conducted to investigate the repeated dose toxicity of DA-9601, an antiulcer agent of Artemisia app. extract, in rats. DA-9601 was administered orally once a day for 4 weeks to 10 males and 10 females per group at doses of 0(vehicle control), 125, 500 or 2000 mg/kg/day. Throughout the study, no treatment-related deaths and clinical signs were observed. In female rats receiving 125 mg/kg of DA-9601, water consumption increased slightly on day 4, 11 and 25. Hematological examination showed a decrease of MCV and an increase of PLT in male rats at the doses of 500 and 2000 mg/kg groups. Blood biochemistry revealed slight decreases of cholesterol, BUN and Na in male rats and decreases of total bilirubin and creatinine and slight increases of globulin and Cl in female rats. The organ weights at the end of 4 weeks showed slight changes in some organs of treated groups. But, all these changes were not considered to be of toxicological importance, because they did not show dose-response relationship and relevance to gross and microscopic findings. Histopathologically, abnormal treatment-related changes were not observed in any organ and target organs were not detected. On the basis of these results, the NOAEL(no-observed-adverse-effect level) of DA-9601 was estimated to be more than 2000 mg/kg/day under the conditions tested.

• Journal of Plant Biotechnology
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• v.38 no.1
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• pp.94-104
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• 2011

Salt stress is a major environmental factor influencing plant growth and development. To identify salt tolerance determinants, we systematically screened salt sensitive rice mutants by use of the Activator/Dissociation (Ac/Ds) transposon tagging system. In this study, we focused on the salt sensitive mutant line, designated SSM-1. A gene encoding a NAC transcription factor homologue was disrupted by the insertion of a Ds transposon into SSM-1 line. The OsNAC075 gene (EU541472) has 7 exons and encodes a protein (486-aa) containing the NAC domain in its N-terminal region. Sequence comparison showed that the OsNAC075 protein had a strikingly conserved region at the N-terminus, which is considered as the characteristic of the NAC protein family. OsNAC075 protein was orthologous to Arabidopsis thaliana ANAC075. Phylogenetic analysis confirmed OsNAC075 belonged to the OsNAC3 subfamily, which plays an important role in response to stress stimuli. RT-PCR analysis showed that the expression of OsNAC075 gene was rapidly and strongly induced by stresses such as NaCl, ABA and low temperature ($4^{\circ}C$). Our data suggest that OsNAC075 holds promising utility in improving salt tolerance in rice.

• Journal of Applied Biological Chemistry
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• v.50 no.4
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• pp.227-233
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• 2007

We characterized a full-length cDNA of CaCOP1 from pepper. Phylogenetic analysis based on the deduced amino acid sequence of CaCOP1 cDNA revealed high sequence similarity to the COP1 gene in Oryza sativa (84% identity). CaCOP1 shares high sequence identity with regulatory protein in Arabidopsis (84%), constitutively photomorphogenic 1 protein in Pisum sativum (81%) and COP1 homolog in Lycopersicon esculentum (79%). CaCOP1 gene exists single copy in the chili pepper genome. Expression of CaCOP1 was reduced in response to inoculation of non-host pathogens. The expression of this gene under abiotic and oxidative stresses was investigated, including 200 mM NaCl, 200 mM mannitol, cold ($4^{\circ}C$), 100 ${\mu}M$ abscisic acid (ABA), and 10 mM hydrogen peroxide ($H_2O_2$). CaCOP1 was induced significantly 3 h after low temperature treatment but not by dehydration or high salinity. Moreover, CaCOP1 was not induced by plant hormone ABA. These observations suggest that CaCOP1 gene plays a role in abiotic stress and may be belong to ABA-independent regulation system.

• Journal of Surface Science and Engineering
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• v.42 no.2
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• pp.79-85
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• 2009

We aimed to develop a Fe-($16{\sim}19$)Cr-($0.1{\sim}0.6$)Ti-($0.1{\sim}0.6$)Nb stainless steel for automotive exhaust parts with high corrosion resistance. The alloys with high Cr content showed high resistance to general corrosion and also localized corrosion. The increase of Ti and Nb contents resulted in a linear increase in the general corrosion resistance, while the pitting potential was improved by addition of these elements up to about 0.4 wt.%. The low-carbon Fe-17Cr-0.4Ti-0.4Nb alloy annealed at $850^{\circ}C$ and air-cooled was considered to be the optimum alloy for our purpose with the critical anodic current density of $247{\mu}A/cm^2$ in 0.05 M $H_2SO_4$ solution and the pitting potential of 310 mVSCE in 0.2 M NaCl solution.

• Journal of Microbiology and Biotechnology
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• v.15 no.3
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• pp.579-586
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• 2005

When subjected to hyperosmotic pressure by NaCl addition, H69K-NGD transfectoma, like KR12H-2 transfectoma, displayed decreased specific growth rate (${\mu}$) and increased specific antibody productivity ($q_{Ab}$): Elevation of medium osmolality from 280 mOsm/kg to 415 mOsm/kg decreased ${\mu}$ by $79\%$ in batch cultures of H69K-NGD transfectoma, while it increased $q_{Ab}$ by $103\%$. However, unlike KR12H-2 tranfectoma, enhanced $q_{Ab}$ of H69K-NGD transfectoma at hyperosmolalities was not due to elevated levels of Ig mRNAs. In hyperosmotic cultures of H69K-NGD transfectoma, heavy-chain mRNA per cell was not enhanced with increasing osmolality. Hyperosmotic pressure was found to preferentially enhance immunoglobulin (Ig) translation rates of H69K-NGD transfectoma. However, under hyperosmotic pressure, the translation rate of Ig polypeptides was not enhanced as much as $q_{Ab}$. This result suggests that hyperosmotic pressure also influences the post-translational process. Taken together, the results obtained show that intracellular response of transfectomas to hyperosmotic pressure, in regard to the main intracellular steps of the antibody secretory pathway, is cell-line dependent.