• Journal of the Korean Chemical Society
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• v.20 no.1
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• pp.56-58
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• 1976

A new mechanism is proposed for the reduction of nitrobenzene in basic solution that does not involve hydroxylamine as an intermediate. This paper presents evidence that the azoxybenzene is not formed from the hydroxylamine, but formed instead from the dimerization of nitrosobenzene.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.4055-4058
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• 2011

• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.420-422
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• 2004

• Bulletin of the Korean Chemical Society
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• v.16 no.12
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• pp.1148-1152
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• 1995

Oxidative dimerization of methane to C2-hydrocarbons was performed over lead aluminate spinel catalysts. These spinel catalysts were prepared by co-precipitation, aerogel, and sol-gel methods. The active phase of lead aluminate oxides was found to be PbAl2O4 spinel. The activities of the catalysts were strongly dependent on the preparation method as well as the composition of PbAl2O4 phase. The proper oxygen mobility of PbAl2O4 spinel oxides appeared to be important to get high catalytic activity and selectivity for C2-hydrocarbon formation.

• Archives of Pharmacal Research
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• v.22 no.3
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• pp.306-308
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• 1999

The oxidative dimerization of ferulic acid has been carried out using horse-radish peroxidase as catalyst to give a dihydrobenzofuran neolignan (1), the structure of which was elucidated as (2SR, 3RS)-2,3-dihydro-2-(4-hydroxy-3-methoxyphenyl)-3n-butoxycarbonyl-5-(2E-carboxyethenyl)-7methoxybenzofuran by spectroscopic analyses. This compound showed more potent cytotoxicity against several tumor cell lines than the starting material.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.755-762
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• 2005

A series of catalysts, NiO/$CeO_2-ZrO_2/WO_3$, for ethylene dimerization was prepared by the precipitation and impregnation methods. For NiO/$CeO_2-ZrO_2/WO_3$ sample, no diffraction line of nickel oxide was observed up to 40 wt%, indicating good dispersion of nickel oxide on the surface of catalyst. The hexagonal and monoclinic phases of $WO_3$ up to the calcination temperature of 500 ${^{\circ}C}$ were observed, whereas the hexagonal phase of WO3 completely was transformed into monoclinic phase of $WO_3$ at 600 ${^{\circ}C}$ and above. The role of $CeO_2$ in the catalysts was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity. The catalytic activities for ethylene dimerization were correlated with the acidity of catalysts measured by the ammonia chemisorption method. 25-NiO/5-$CeO_2-ZrO_2/15-WO_3$ containing 25 wt% NiO, 15 wt% $WO_3$ and 5 mol% $CeO_2$, and calcined at 400 ${^{\circ}C}$ exhibited a maximum catalytic activity due to the effects of $WO_3$ modifying and $CeO_2$ doping.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1749-1756
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• 2005

The $NiSO_4$ supported on FeO-promoted $ZrO_2$ catalysts were prepared by the impregnation method. FeOpromoted $ZrO_2$ was prepared by the coprecipitation method using a mixed aqueous solution of zirconium oxychloride and iron nitrate solution followed by adding an aqueous ammonia solution. The addition of nickel sulfate (or FeO) to $ZrO_2$ shifted the phase transition of $ZrO_2$ (from amorphous to tetragonal) to higher temperatures because of the interaction between nickel sulfate (or FeO) and $ZrO_2$. 10-$NiSO_4$/5-FeO-$ZrO_2$ containing 10 wt % $NiSO_4$ and 5 mol % FeO, and calcined at 500 ${^{\circ}C}$ exhibited a maximum catalytic activity for ethylene dimerization. $NiSO_4$/FeO-$ZrO_2$ catalysts was very effective for ethylene dimerization even at room temperature, but FeO-$ZrO_2$ without $NiSO_4$ did not exhibit any catalytic activity at all. The catalytic activities were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The addition of FeO up to 5 mol % enhanced the acidity, surface area, thermal property, and catalytic activities of catalysts gradually, due to the interaction between FeO and $ZrO_2$ and due to consequent formation of Fe-O-Zr bond.

• Journal of Korean Neurosurgical Society
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• v.29 no.6
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• pp.725-730
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• 2000

Purpose : The subcellular localization of E1B-19k has been known cytosol or nuclear membrane by immunohistochemical staining and could dimerize with Bax to regulate cell death also known by the in-vitro immunoprecipitation. We planed to confirm this dimerization of E1B-19k with Bax in vivo in Cos-7 cells by using green fluorescent protein. Material and Method : We cloned E1B-19k and Bax into C3-EGFP. C3-EGFP-E1B-19k, C3-EGFP-Bax, and C3-EGFP-E1B-19k and pcDNA3-Bax were transfected into Cos-7 cells. We explored location of E1B-19k and Bax, and confirmed its dimerization with Bax in transfected living healthy Cos-7 cells by following green fluorescent protein of E1B-19k on the confocal microscope. Results : E1B-19k was located diffusely in cytoplasm and in nucleus but not in mitochondria. It prevented cell death from the apoptosis by staurosporine but its location was not changed. GFP-E1B-19k is not changed its intracellular location with Bax even with staurosporine. Conclusion : These results support that E1B-19k does not localize in mitochondria nor dimerize with Bax even with staurosporine. We could anticipate E1B-19k prevent cell death via the other dimerizing partner or pathways.

• Molecules and Cells
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• v.25 no.2
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• pp.253-257
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• 2008

Acrolein is a highly electrophilic ${\alpha},{\beta}$-unsaturated aldehyde present in a number of environmental sources, especially cigarette smoke. It reacts strongly with the thiol groups of cysteine residues by Michael addition and has been reported to inhibit nuclear $factor-{\kappa}B$ ($NF-{\kappa}B$) activation by lipopolysaccharide (LPS). The mechanism by which it inhibits $NF-{\kappa}B$ is not clear. Toll-like receptors (TLRs) play a key role in sensing microbial components and inducing innate immune responses, and LPS-induced dimerization of TLR4 is required for activation of downstream signaling pathways. Thus, dimerization of TLR4 may be one of the first events involved in activating TLR4-mediated signaling pathways. Stimulation of TLR4 by LPS activates both myeloid differential factor 88 (MyD88)- and TIR domain-containing adapter inducing $IFN{\beta}$ (TRIF)-dependent signaling pathways leading to activation of $NF-{\kappa}B$ and IFN-regulatory factor 3 (IRF3). Acrolein inhibited $NF-{\kappa}B$ and IRF3 activation by LPS, but it did not inhibit $NF-{\kappa}B$ or IRF3 activation by MyD88, inhibitor ${\kappa}B$ kinase $(IKK){\beta}$, TRIF, or TNF-receptor-associated factor family member-associated $NF-{\kappa}B$ activator (TANK)-binding kinase 1 (TBK1). Acrolein inhibited LPS-induced dimerization of TLR4, which resulted in the down-regulation of $NF-{\kappa}B$ and IRF3 activation. These results suggest that activation of TLRs and subsequent immune/inflammatory responses induced by endogenous molecules or chronic infection can be modulated by certain chemicals with a structural motif that enables Michael addition.

• BMB Reports
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• v.51 no.4
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• pp.163-164
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• 2018

CONSTANS (CO) induces the expression of FLOWERING LOCUS T (FT) in the photoperiodic pathway, and thereby regulates the seasonal timing of flowering. CO expression is induced and CO protein is stabilized by FLAVIN-BINDING KELCH REPEAT F-BOX PROTEIN 1 (FKF1) in the late afternoon, while CO is degraded by CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) during the night. These regulatory cascades were thought to act independently. In our study, we investigated the relationship between FKF1 and COP1 in the regulation of CO stability in response to ambient light conditions. A genetic analysis revealed that FKF1 acts as a direct upstream negative regulator of COP1, in which cop1 mutation is epistatic to fkf1 mutation in the photoperiodic regulation of flowering. COP1 activity requires the formation of a hetero-tetramer with SUPPRESSOR OF PHYA-105 (SPA1), [$(COP1)_2(SPA1)_2$]. Light-activated FKF1 has an increased binding capacity for COP1, forming a FKF1-COP1 hetero-dimer, and inhibiting COP1 homo-dimerization at its coiled-coil (CC) domain. Mutations in the CC domain result in poor COP1 dimerization and misregulation of photoperiodic floral induction. We propose that FKF1 represses COP1 activity by inhibiting COP1 dimerization in the late afternoon under long-day conditions, resulting in early flowering.