• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2125-2134
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• 2015

IrrE is a highly conserved global regulator in the Deinococcus genus and contributes to survival from high doses of UV radiation, ionizing radiation, and desiccation. Drad-IrrE and Dgob-IrrE from Deinococcus radiodurans and Deinococcus gobiensis I-0 each share 66% sequence identity. However, Dgob-IrrE showed a stronger protection phenotype against UV radiation than Drad-IrrE in the D. radiodurans irrE-deletion mutant (ΔirrE), which may be due to amino acid residues differences around the DNA-binding HTH domain. Site-directed mutagenesis was used to generate a Drad-IrrE A184S single mutant, which has been characterized and compared with the ΔirrE mutant complemented strain with Drad-irrE, designated ΔirrE-E. The effects of the A184S mutation following UV radiation and mitomycin C (MMC) shock were determined. The A184S mutant displayed significantly increased resistance to UV radiation and MMC shock. The corresponding A184 site in Dgob-IrrE was inversely mutated, generating the S131A mutant, which exhibited a loss of resistance against UV radiation, MMC shock, and desiccation. qPCR analysis revealed that critical genes in the DNA repair system, such as recA, pprA, uvrA, and ddrB, were remarkably induced after UV radiation and MMC shock in the ΔirrE-IE and A184S mutants. These data suggested that A184S improves the ability against UV radiation and MMC shock, providing new insights into the modification of IrrE. We speculated that the serine residue may determine the efficiency of DNA binding, leading to the increased expression of IrrE-dependent genes important for protection against DNA damage.

• Journal of Microbiology and Biotechnology
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• v.20 no.7
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• pp.1156-1162
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• 2010

During ethanol fermentation, bacterial strains may encounter various stresses, such as ethanol and acid shock, which adversely affect cell viability and the production of ethanol. Therefore, ethanologenic strains that tolerate abiotic stresses are highly desirable. Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation, ultraviolet light, and desiccation, and therefore constitute an important pool of extreme resistance genes. The irrE gene encodes a general switch responsible for the extreme radioresistance of D. radiodurans. Here, we present evidence that IrrE, acting as a global regulator, confers high stress tolerance to a Zymomonas mobilis strain. Expression of the gene protected Z. mobilis cells against ethanol, acid, osmotic, and thermal shocks. It also markedly improved cell viability, the expression levels and enzyme activities of pyruvate decarboxylase and alcohol dehydrogenase, and the production of ethanol under both ethanol and acid stresses. These data suggest that irrE is a potentially promising gene for improving the abiotic stress tolerance of ethanologenic bacterial strains.

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1030-1034
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• 2013

Elimination reactions of $(E)-2,4-(NO_2)_2C_6H_2CH=NOC_6H_3-2-X-4-NO_2$ (1a-e) promoted by $R_3N/R_3NH^+$ in 70 mol % MeCN(aq) have been studied kinetically. The reactions are second-order and exhibit Br$\ddot{o}$nsted ${\beta}$ = 0.80-0.84 and ${\mid}{\beta}_{lg}{\mid}$ = 0.39-0.42, respectively. For all leaving groups and bases employed in this study, the ${\beta}$ and ${\mid}{\beta}_{lg}{\mid}$ values remained almost the same. The results can be described by a negligible $p_{xy}$ interaction coefficient, $p_{xy}={\partial}{\beta}/pK_{lg}={\partial}{\beta}_{lg}/pK_{BH}{\approx}0$, which describes the interaction between the base catalyst and the leaving group. The negligible pxy interaction coefficient is consistent with the $(E1cb)_{irr}$ mechanism. Change of the base-solvent system from $R_3N$/MeCN to $R_3N/R_3NH^+$-70 mol % MeCN(aq) changed the reaction mechanism from E2 to $(E1cb)_{irr}$. Noteworthy was the relative insensitivity of the transition state structure to the reaction mechanism change.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.5.1-5.8
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• 2020

Objectives: The obturation quality of MTA, Biodentine, Total Fill BC root canal sealer (RCS), and warm gutta-percha (WGP) in teeth with simulated internal root resorption (IRR) was evaluated by using micro-computed tomography. Materials and Methods: Standardized IRR cavities were created using 40 extracted maxillary central incisor teeth and randomly assigned into 4 groups (n = 10). IRR cavities were filled with MTA, Biodentine, Total Fill BC RCS (bulk-fill form) and WGP + Total Fill BC RCS. Percentage of voids between resorptive cavity walls and obturation material (external void), and inside the filling materials (internal voids) were measured. Results: Total Fill BC sealer in the bulk-fill form presented significantly highest values of external and internal void percentages (p < 0.05). Biodentine showed a significantly lowest external void percentage (p < 0.05). WGP + Total Fill BC RCS presented significantly lower values of internal void percentages than all groups (p < 0.05), except Biodentine (p > 0.05). Conclusion: None of the filling materials were created void-free obturation in resorption cavities. Biodentine may favor its application in teeth with IRR over Angelus MTA and bulkfill form of Total Fill BC.

• Journal of the Korea Safety Management & Science
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• v.11 no.3
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• pp.181-188
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• 2009

This paper presents the economic validity with the cost/benefit analysis on establishing R&D Supreme Academy. To evaluate the profitability of R&D Supreme Academy, willingness to pay (WTP) is measured by contingent valuation method (CVM) and then the net present value (NPV), internal rate of return (IRR) and benefit/cost ratio(BCR) are calculated. The results of economic evaluation verified that the establishment of R&D Supreme Academy is timely and effective in an economic perspective.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.1043-1046
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• 2010

• The Journal of Fisheries Business Administration
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• v.43 no.3
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• pp.31-41
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• 2012

This paper was conducted to study the economic valuation for Nursery-Phase production of the tidal flat oyster in Korea. Benefit-cost(B/C) model used to indicate the effects of economic valuation. Using discounting rates(i.e., 4.5%, 6.5% and 8.5%), the model compared revenues and costs that occur at different times from 2012 to 2018. This study also estimated various submodels, which are Benefit Cost Ratio(B/C ratio), Net Present Value(NPV), Internal Ration of Return(IRR), to compare profit of Nursery-Phase production styles and analyzed returns to evaluate the scenarios. Sensitivity analysis were conducted for various scenarios. The results suggest as follows. First, the oyster spat to the shell height of 3~5cm was more profit than the shell height of 1~3cm. Second, all of sensitivity analysis with submodels were economic valuation such that B/C ratio > 1, NPV > 0 and IRR > discounting rate. Third, the payback period was about 3years after installed Nursery-Phase production system.

• Journal of applied mathematics & informatics
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• v.32 no.5_6
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• pp.675-685
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• 2014

Suppose G is a simple graph. The irregularity of G, irr(G), is the summation of imb(e) over all edges $uv=e{\in}G$, where imb(e) = |deg(u)-deg(v)|. In this paper, we investigate the behavior of this graph parameter under some old and new graph operations.

• Restorative Dentistry and Endodontics
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• v.45 no.4
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• pp.43.1-43.9
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• 2020

A variety of therapeutic modalities can be used for the endodontic treatment of a traumatized tooth with internal root resorption (IRR). The authors present a case report of the successful restoration of a traumatized upper central incisor that was weakened due to severe IRR and subsequent periapical lesion formation. A 20-year-old female patient was referred to our clinic with severe internal resorption and subsequent periapical pathosis destroying the buccal bone wall. Root canal treatment had been initiated previously at another dental practice, but at that time, the patient's condition could not be managed even with several treatments. After cone-beam computed tomography imaging and proper chemomechanical cleaning, the tooth was managed with a mineral trioxide aggregate plug followed by root canal filling using short fiber-reinforced composite, known as the Bioblock technique. This report is the first documentation of the use of the Bioblock technique in the restoration of a traumatized tooth. The Bioblock technique appears to be ideal for restoring wide irregular root canals, as in cases of severe internal resorption, because it can uniquely fill out the hollow irregularities of the canal. However, further long-term clinical investigations are required to provide additional information about this new technique.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.69.2-69.2
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• 2011

The discovery of dark energy from Type Ia supernovae (SN Ia) is based on the implicit assumption that the look-back time evolution of SN Ia luminosity, after light-curve corrections, would be negligible. A strong support for this assumption was the apparent insensitivity of SN Ia distances across the host galaxy morphologies. However, Hicken et al. 2009 (H09) shows a systematic difference in the Hubble residual (HR) of $0.144{\pm}0.070$ mag between the E-S0 and Scd/Sd/Irr galaxies, after light-curve corrections. If true, this indicates that the light-curve fitters used by the SN Ia community can not correct for the population age (and therefore the evolution) effect. In order to confirm this, we have combined nearby SN Ia samples and the first-year SDSS-II SN Survey. The SNANA package was used for analyzing SN Ia light-curve, both for the MLCS2k2 and SALT2 fitters. We find a systematic difference in the HR of $0.10-0.13{\pm}0.030$ mag between E-S0 and Scd/Sd/Irr galaxies, which is in agreement with the result of H09, but now at the 3-5 ${\sigma}$ level. Considering the significant difference in the mean age of stellar population between these morphological types, the difference in the HR reported here suggests that the evolution effect of SN Ia luminosity should be considered in the cosmological application of SN Ia data.