• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.7
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• pp.477-485
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• 2009

The study of nitrogen dilution effect on the flame stability was experimentally investigated in a non-premixed turbulent lifted hydrogen jet with coaxial air. Hydrogen gas was used as a fuel and coaxial air was used to make flame liftoff. Each of hydrogen and air were injected through axisymetric inner and outer nozzles ($d_F=3.65\;mm$ and $d_A=14.1\;mm$). And both fuel jet and coaxial air velocity were fixed as $u_F=200\;m/s$ and $u_A=16\;m/s$, while the mole fraction of nitrogen diluents gas was varied from 0.0 to 0.2 with 0.1 step. For the analysis of flame structure and the flame stabilization mechanism, the simultaneous measurement of PIV/OH PLIF laser diagnostics had been performed. The stabilization point was selected in the most upstream region of the flame base and defined as the point where the turbulent flame propagation velocity was equal to the axial component of local flow velocity. We found that the turbulent flame propagation velocity increased with the decrease of nitrogen mole fraction. We concluded that the turbulent flame propagation velocity was expressed as a function of turbulent intensity and axial strain rate, even though nitrogen diluents mole fraction was changed.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1182-1190
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• 2014

$Cd_{1-x}Zn_xS$-sensitized $K_4Nb_6O_{17}$ composite photocatalysts (designated $Cd_{1-x}Zn_xS/K_4Nb_6O_{17}$) were prepared via a simple deposition-precipitation method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), $N_2$ sorption, ultraviolet-visible light diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence measurements (PL), and X-ray photoelectron spectroscopy (XPS). The $Cd_{0.8}Zn_{0.2}S$ particles were scattered on the surface of $K_4Nb_6O_{17}$, and had a relatively uniform size distribution around 50 nm. The absorption edge of $K_4Nb_6O_{17}$ was shifted to the visible light region and the recombination of photo-generated electrons and holes suppressed after $Cd_{0.8}Zn_{0.2}S$ loading. The $Cd_{0.8}Zn_{0.2}S$(25 wt %)/$K_4Nb_6O_{17}$ composite possessed the highest photocatalytic activity for hydrogen production under visible light irradiation, evolving 8.278 mmol/g in 3 h. Recyclability tests were performed, and the composite photocatalysts were found to be fairly stable. The mechanism of charge separation between the photogenerated electrons and holes at the $Cd_{0.8}Zn_{0.2}S/K_4Nb_6O_{17}$ composite was discussed.

• Journal of Korean Medicine Rehabilitation
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• v.25 no.2
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• pp.1-13
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• 2015

Objectives Methicillin-Resistant Staphylococcus aureus (MRSA) is a human pathogen and a major cause of hospital-acquired infections. New antibacterial agents that have not been compromised by bacterial resistance are needed to treat MRSA-related infections. In this study, we investigated the antimicrobial activity ofethanol extract of Haedokgeumhwa-san (HGH) which prescription is composed of korean medicine against MRSA. Methods The antibacterial activity of HGH extract was evaluated against MRSA strains by using the Disc diffusion method, broth microdilution method (minimal inhibitory concentration; MIC), checkerboard dilution test, and time-kill test; its mechanism of action was investigated by bacteriolysis, detergent or ATPase inhibitors. The checkerboard dilution test was used to examined synergistic effect of ampicillin, oxacillin, ciprofloxacin, vancomycin, gentamicin and norfloxacin in combination with HGH ethanol extract. A time-kill assay was performed a survival curve which was obtained by plotting viable colony counts depending on time on bacterial growth. Results The minimum inhibitory concentration (MIC) of ethanol extract (HGH) ranged from 1,000 to $2,000{\mu}g/mL$ against all the tested bacterial strains, respectively. We are able to confirm that HGH extract has potentially strong antibacterial activity. In the checkerboard dilution test, fractional inhibitory concentration index of HGH in combination with antibiotics indicated synergy or partial synergism against S. aureus. A time-kill study showed that the growth of the tested bacteria was considerably inhibited after 8 hr of treatment with the combination of HGH with selected antibiotics. For measurement of cell membrane permeability, HGH $250{\sim}1,000{\mu}g/mL$ along with concentration of Triton X-100 (TX) and Tris-(hydroxymethyl) aminomethane (Tris) were used. In the other hand, N,N-dicyclohexylcarbodimide (DCCD) and Sodium azide ($NaN_3$) was used as an inhibitor of ATPase. TX, Tris, DCCD and $NaN_3$ cooperation against S. aureus showed synergistic action. Accordingly, antimicrobial activity of HGH was affected by cell membrane and inhibitor of ATPase. Conclusions These results suggest that Haedokgeumhwa-san extract has antibacterial activity, and that HGH extract offers a potential as a natural antibiotic against MRSA.

• Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.314-328
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• 2024

The mechanism for the elimination of xenobiotics undergoes three different phases of reactions in organisms. Among these, glutathione S-transferases (GSTs) are classified as phase II detoxification enzymes, catalyzing the conjugation of electrophilic substrates to glutathione or reduced hydroperoxides. This study aimed to investigate the molecular characteristics, detoxification functions, and immune responses of GST omega (LhGSTO1) and kappa (LhGSTK1) in redlip mullet. The open reading frames of LhGSTO1 (720 bp) and LhGSTK1 (687 bp) encoded proteins of 239 and 228 amino acids, respectively. Sequence analysis revealed that LhGSTO1 and LhGSTK1 possessed GSH-binding sites in their N-terminal domains. Substrate-binding sites in the C-terminal domain were exclusively identified in LhGSTO1. In the tissue-specific transcription profile analysis, both LhGSTO1 and LhGSTK1 were ubiquitously expressed in all tissues of healthy mullets. Temporal expression analysis of LhGSTO1 and LhGSTK1 in the blood showed that their expression was significantly modulated by polyinosinic:polycytidylic (poly I:C), lipopolysaccharide (LPS), and Lactococcus garvieae. Different chemical and cellular assays were performed to assess the detoxification and cellular protective abilities of the two proteins. A substrate specificity test using the recombinant proteins revealed that both proteins possessed specific activity toward 1-chloro-2,4-dinitrobenzene (CDNB). In the disk diffusion assay, the smallest clearance zones were observed for LhGSTO1 and LGSTK1 against CdCl₂. In the cell protection assay, both LhGSTO1 and LhGSTK1 showed significant Cd detoxification ability compared to the control. Collectively, these results demonstrate that GST omega and kappa are involved in host defense against immune stimulants and xenobiotics in redlip mullet.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.10
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• pp.543-550
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• 2016

Amine-type PP-g-VBC-EDA adsorbent, which possesses anionic exchangeable function, was prepared through photoinduced graft polymerization of vinylbenzyl chloride (VBC) onto polypropylene non-woven fabric and subsequent amination reaction using ethylenediamine (EDA). Adsorption characteristics of anionic nutrients on the PP-g-VBC-EDA adsorbent have been studied by batch adsorption experiments. The equilibrium data well fitted the Langmuir isotherm model, and the maximum monolayer sorption capacity was found to be 59.9 mg/g for $NO_3-N$ and 111.4 mg/g for $PO_4-P$. The adsorption energies were higher than 8 kJ/mol indicating anion-exchange process as the primary adsorption mechanism. The pseudo-second order kinetic model described well the kinetic data and resulted in the activation energy of 9.8-36.7 kJ/mol suggesting that the overall rates of $NO_3-N$ and $PO_4-P$ adsorption are controlled by the chemical process. Thermodynamic parameters such as ${\Delta}G^o$, ${\Delta}H^o$ and ${\Delta}S^o$ indicated that the adsorption nature of PP-g-VBC-EDA for anionic nutrients is spontaneous and exothermic. The PP-g-VBC-EDA could be regenerated by washing with 0.1 N HCl.

• Journal of Microbiology and Biotechnology
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• v.19 no.4
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• pp.409-415
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• 2009

Galactomyces geotrichum MTCC 1360 degraded the Scarlet RR(100 mg/l) dye within 18 h, under shaking conditions(150 rpm) in malt yeast medium. The optimum pH and the temperature for decolorization were pH 12 and $50^{\circ}C$, respectively. Enzymatic studies revealed an induction of the enzymes, including flavin reductase during the initial stage and lignin peroxidase after complete decolorization of the dye. Decolorization of the dye was induced by the addition of $CaCO_3$ to the medium. EDTA had an inhibitory effect on the dye decolorization along with the laccase activity. The metabolites formed after complete decolorization were analyzed by UV-VIS, HPLC, and FTIR. The GC/MS identification of 3 H quinazolin-4-one, 2-ethylamino-acetamide, 1-chloro-4-nitro-benzene, N-(4-chloro-phenyl)-hydroxylamine, and 4-chloro-pheny-lamine as the final metabolites corroborated with the degradation of Scarlet RR. The phytotoxicity study revealed the nontoxic nature of the final metabolites. A possible degradation pathway is suggested to understand the mechanism used by G. geotrichum and thereby aiding development of technologies for the application of this organism to the cleaning-up of aquatic and terrestrial environments.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.144.1-144
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• 2003

Attenuated viruses can protect their hosts against challenge to their related viruses. Increasing evidence shows that mutations of the tobamoviral 126/183 kDa protein play a major role in the viral attenuation and contribute to the cross protection mechanism. In this study, four mutants of Pepper mild mottle virus (PMMoV) have been constructed by mutagenesis; two mutants, pTPpoly348 and pTPpoly762, were substituted in the middle of replicase gene, and the others, pTPL3D:: $\Delta$6207 and pTPL3D:: $\Delta$6219, were deletion mutants made by deleting some parts of pseudoknot structures of the 3' noncoding region (NCR) of the virus. Progeny viruses generated from the four mutants were infectious on N. benthamiana plants with symptomless or mild mosaic symptom. Replication efficiency and viral product accumulations of four mutants were assessed by Northern and Western blot analyses on BY-2 protoplast cells. Accumulation of CP for the pTPL3D:: $\Delta$6207 and pTPL3D:: $\Delta$6219 were lower than that of other mutants and wild type virus. These data suggest that the 3'-NCR mutations contribute to the viral gene expression in host tissues, while mutants of replicase gene rather govern the symptom expression.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.4
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• pp.385-397
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• 1992

Current measurements at 3 sections and numerical experiments were carried out in Masan Bay to understand the effect of the wind on the residual currents and pollutant transport. The vertical distribution of horizontal velocities were directly affected by the wind at the depths of 1m and 2m beneath the sea surface. Analysis of the velocity data suggested that changes in the vertical gravitational circulation contributed to the net circulation. The net transport of water through the northern part of the bay was observed to be landward, with wind-induced transport of about 100m super(3)/s. Hence, wind is concluded to be the dominant mechanism driving the net circulation in the northern area of Masan Bay. Numerical experiments are shown that when S wind with 5m/s blew, northern area of the bay was generated the horizontal circulation of clockwise and local gyre. On the contrary of those, N wind made her to the anti-clockwise. In the case of no wind, the tidal residual current(constant flow) is very small or neglected except the bay-mouth. The inflow or outflow pattern of the mouth is considered as the flows generated by tidal residual current only. The distance of wind-induced transport of pollutant was as long as 2 times of no wind during the one tidal period.

• Molecules and Cells
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• v.38 no.1
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• pp.58-64
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• 2015

Activating transcription factor-3 (ATF3) acts as a negative regulator of cytokine production during Gram-negative bacterial infection. A recent study reported that ATF3 provides protection from Streptococcus pneumoniae infection by activating cytokines. However, the mechanism by which S. pneumoniae induces ATF3 after infection is still unknown. In this study, we show that ATF3 was upregulated via Toll-like receptor (TLR) pathways in response to S. pneumoniae infection in vitro. Induction was mediated by TLR4 and TLR2, which are in the TLR family. The expression of ATF3 was induced by pneumolysin (PLY), a potent pneumococcal virulence factor, via the TLR4 pathway. Furthermore, ATF3 induction is mediated by p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK). Thus, this study reveals a potential role of PLY in modulating ATF3 expression, which is required for the regulation of immune responses against pneumococcal infection in macrophages.

• Journal of Ginseng Research
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• v.47 no.2
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• pp.329-336
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• 2023

Background: Panax ginseng Meyer is a medicinal plant well-known for its antiviral activities against various viruses, but its antiviral effect on coronavirus has not yet been studied thoroughly. The antiviral activity of Korean Red Ginseng (KRG) and ten ginsenosides against Human coronavirus OC43 (HCoV-OC43) was investigated in vitro. Methods: The antiviral response and mechanism of action of KRG extract and ginsenoside Rc, Re, Rf, Rg1, Rg2-20 (R) and -20 (S), Rg3-20 (R) and -20 (S), and Rh2-20 (R) and -20 (S), against the human coronavirus strain OC43 were investigated by using plaque assay, time of addition assay, real-time PCR, and FACS analysis. Results: Virus plaque formation was reduced in KRG extract-treated and HCoV-OC43-infected HCT-8 cells. KRG extract decreased the viral proteins (Nucleocapsid protein and Spike protein) and mRNA (N and M gene) expression, while increased the expression of interferon genes. Conclusion: KRG extract exhibits antiviral activity by enhancing the expression of interferons and can be used in treating infections caused by HCoV-OC43.