• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.765-773
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• 2009

Edwardsiella tarda is a pathogen with a broad host range that includes human and animals. The E. tarda hemolysin (Eth) system, which comprises EthA and EthB, is a noted virulence element that is widely distributed in pathogenic isolates of E. tarda. Previous study has shown that the expression of ethB is regulated by iron, which suggests the possibility that the ferric uptake regulator (Fur) is involved in the regulation of ethB. The work presented in this report supports the previous findings and demonstrates that ethB expression was decreased under conditions when the E. tarda Fur ($Fur_{Et}$) was overproduced, and enhanced when $Fur_{Et}$ was inactivated. We also identified a second ethB regulator, EthR, which is a transcription regulator of the GntR family. EthR represses ethB expression by direct interaction with the ethB promoter region. In addition to ethB, EthR also modulates, but positively, luxS expression and AI-2 production by binding to the luxS promoter region. The expression of ethR itself is subject to negative autoregulation; interference with this regulation by overexpressing ethR during the process of infection caused (i) drastic changes in ethB and luxS expressions, (ii) vitiation in the tissue dissemination and survival ability of the bacterium, and (iii) significant attenuation of the overall bacterial virulence. These results not only provide new insights into the regulation mechanisms of the Eth hemolysin and LuxS/AI-2 quorum sensing systems but also highlight the importance of these systems in bacterial virulence.

• The Bulletin of The Korean Astronomical Society
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• v.34 no.1
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• pp.112-112
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• 2009

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1124-1131
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• 2009

Acanthopanax senticosus has been used in East Asia as a traditional medicine. The purpose of this study is the investigation of an extraction method for A. senticosus var subinermis (ASvS) leaves to improve their antioxidant and anti-inflammatory activities. Six extracts were prepared: extracted with water (W), ethanol (Eth), water or ethanol after ultra high pressure (WP, EthP), and water or ethanol after an extrusion process (WEx, EthEx). Diphenylpicrylhydrazyl (DPPH) radical scavenging activity and ferric reducing ability showed that all extracts had a significant antioxidant activity. In anti-inflammatory activities, Eth and EthEx significantly inhibited the release of lipopolysaccharide (LPS)-induced nitric oxide (NO), tumor necrosis factor (TNF)-${\alpha}$, and interleukin (IL)-$1{\beta}$ independent of cell viability in RAW 264.7 macrophage cells. Inducible NO synthase (iNOS) protein was significantly decreased by EthEx. These findings present that Eth and EthEx extracts of ASvS leaves have anti-inflammatory activities, and EthEx extract suppresses LPS-induced NO through the down-regulation of iNOS and pro-inflammatory cytokines.

• Bulletin of the Korean Space Science Society
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• 2009.04a
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• pp.54.2-54.2
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• 2009

• Bulletin of the Korean Space Science Society
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• 2007.04a
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• pp.41-41
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• 2007

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.34.1-34.1
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• 2016

The ultra hard X-ray band (14-195 keV) provides an important and unbiased way to understand black hole growth and relationship to the host galaxy. The Burst Alert Telescope (BAT) instrument on the Swift satellite has surveyed sky to unprecedented sensitivity, improving the number of known hard X-ray sources by more than a factor of 20 to 836 nearby AGN. The BAT AGN Spectroscopic Survey (BASS) is a study for the first large (N>600) and complete sample of ultra hard X-ray selected AGN with optical spectroscopy. In this talk, I present the observed relationship between black hole mass, bolometric luminosity, and Eddington ratio with optical emission line ratios. We show that [NII]/Ha ratio exhibits a significant correlation with Eddington ratio. We propose that the [NII]/Ha ratio is a useful indicator of Eddington ratio with 0.6 dex of scatter, and that it can be used to measure Eddington ratio and thus black hole mass from the measured bolometric luminosity, even for high redshift obscured AGN.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.847-858
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• 2016

An overview is given on the work of the Laboratory of Nuclear Energy Systems at ETH, Zurich (ETHZ) and of the Laboratory of Thermal Hydraulics at Paul Scherrer Institute (PSI), Switzerland on tight-lattice bundles. Two-phase flow in subchannels of a tight triangular lattice was studied experimentally and by computational fluid dynamics simulations. Two adiabatic facilities were used: (1) a vertical channel modeling a pair of neighboring sub-channels; and (2) an arrangement of four subchannels with one subchannel in the center. The first geometry was equipped with two electrical film sensors placed on opposing rod surfaces forming the subchannel gap. They recorded 2D liquid film thickness distributions on a domain of $16{\times}64$ measuring points each, with a time resolution of 10 kHz. In the bubbly and slug flow regime, information on the bubble size, shape, and velocity and the residual liquid film thickness underneath the bubbles were obtained. The second channel was investigated using cold neutron tomography, which allowed the measurement of average liquid film profiles showing the effect of spacer grids with vanes. The results were reproduced by large eddy simulation + volume of fluid. In the outlook, a novel nonadiabatic subchannel experiment is introduced that can be driven to steady-state dryout. A refrigerant is heated by a heavy water circuit, which allows the application of cold neutron tomography.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.430-431
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.320-321
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.333-334
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• 2005