• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4366-4370
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• 2011

A simple, green and cost-effective protocol was used for the aromatization of 1,3,5-trisubstituted-2-pyrazolines to the corresponding pyrazoles by in situ generation of iodine ($I^+$) from $H_2O_2$/AcOH or SSA or oxalic acid /KI or NaI system under thermal condition with moderate to good yields.

• Bulletin of the Korean Chemical Society
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• 제34권10호
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• pp.3065-3072
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• 2013

Direct synthesis of $H_2O_2$ and in situ oxidative desulfurization of model fuel over Au/Ti-HMS and Au/TS-1 catalysts has been comparatively investigated in water or methanol. Maximum amount (82%) of active $Au^0$ species for $H_2O_2$ synthesis was obtained. Au/Ti-HMS and Au/TS-1 exhibited the contrary performances in $H_2O_2$ synthesis as $CH_3OH/H_2O$ ratio of solvent changed. $H_2O_2$ decomposition and hydrogenation in water was inhibited by the introduction of methanol. Effect of $O_2/H_2$ ratio on $H_2O_2$ concentration, $H_2$ conversion and $H_2O_2$ selectivity revealed a relationship between $H_2O_2$ generation and $H_2$ consumption. The highest dibenzothiophene removal rate (83.2%) was obtained over Au/Ti-HMS in methanol at 1.5 of $O_2/H_2$ ratio and $60^{\circ}C$. But removal of thiophene over Au/TS-1 should be performed in water without heating to obtain a high removal rate (61.3%). Meanwhile, $H_2$ conversion and oxidative desulfurization selectivity of $H_2$ were presented.

• 대한환경공학회지
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• 제27권12호
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• pp.1263-1269
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• 2005

용액 상에서 페놀류에 대해 95%의 분해특성을 지니는 동식물세포유래의 효소(horseradish peroxidase, HRP, EC 1.11.1.7)를 다공성 탄소 전극에 고정화시키고 이를 전기화학 반응기에 도입하여 전극반응에 의해 연속적으로 발생되는 과산화수소를 이용하여 페놀의 분해를 수행하였다. FT-IR 분석을 통해 다공성탄소전극 표면에 HRP의 아민기와 펩티드 결합을 위한 카르복실기가 생성되었음을 확인하였고 가교제(coupling agent)로 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride(EDC)를 이용하여 공유결합으로 고정화시켰다. 또한 HRP를 활성화 시켜 페놀을 처리하기 위해 전해질로 사용된 인산염 완충용액의 농도($10{\sim}200$ mM)와 pH($5.0{\sim}8.0$), 외부 산소 주입량($10{\sim}50$ mL/min)및 potentiostat/galvanosta에 의한 외부 공급전압($-0.2{\sim}-0.8$ volt, vs. Ag/AgCl)의 조건을 달리하며 RVC 전극 표면에서 발생되는 과산화수소 농도 및 전류효율을 고려하여 최적 자체 발생조건을 결정하였다. HRP가 고정화된 RVC 전극은 초기 고정화된 HRP 활성에 대해 4주 동안 89%의 상대적 효소 활성도(relatively enzymatic activity)를 지니는 안정한 전극임을 확인하였으며 실험실 스케일의 연속식 전기화학 반응기에 도입되어 최적 과산화수소의 발생조건에서 86%의 분해 효율을 보였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.524-527
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• 2000

An electroenzymatic system to oxidize veratryl alcohol of on electrodes with in-situ generated hydrogen peroxide was studied. We investigated hydrogen peroxide generation, current efficiency, and veratryl alcohol oxidation in the electrode system at various conditions. The reaction rates of veratryl alcohol oxidation were compared in an electrochemical, an electroenzymatic, and an usual biochemical systems to prove the concept of electroenzymatic oxidation.

• Bulletin of the Korean Chemical Society
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• 제26권10호
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• pp.1525-1528
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• 2005

The synthesis and characterization of ${K_3[Ru(C_2O_4)3]{\cdot}4H_2O\;(C_2O_4}^{2-}$ = oxalato anoin) complex are described, and its redox properties (in buffer solution of pH = 12) have been investigated. This complex is used for in situ generation of oxoruthenates complexes which have been characterized by electronic spectroscopy. Reaction of ${K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ with excess ${S_2O_8}^{2-}$ in molar KOH generates trans-${[RuO_3(OH)_2]^{2-}/S_2O_8}^{2-}$ reagent while with excess ${BrO_3}^-$ in molar $Na_2CO_3$ generates ${[RuO_4]^-/BrO_3}^-$ reagent. Avoiding the direct use of [$RuO_4$] the organic-soluble $(n-Pr_4N)^+[RuO_4]^-$, (TPAP) has been isolated by reaction of $K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ with excess ${BrO_3}^-$ in molar carbonate and n-$Pr_4$NOH. In a mixture of $H_2O/CCl_4$ ruthenium tetraoxide can be generated by reaction of $K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ with excess ${IO_4}^-$. The catalytic activities of oxoruthenates that have been made from $K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ towards the oxidation of benzyl alcohol, piperonyl alcohol, benzaldehyde and benzyl amine at room temperature have been studied.

• Advances in environmental research
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• 제3권3호
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• pp.185-197
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• 2014

Efficient defluorination of perfluorooctanoic acid (PFOA) was achieved by integrating UV irradiation and $Fe^{2+}$ activation of persulfate ($S_2O{_8}^{2-}$). It was found that the UV-$Fe^{2+}$, $Fe^{2+}-S_2O{_8}^{2-}$, and UV-$S_2O{_8}^{2-}$ processes caused defluorination efficiency of 6.4%, 1.6% and 23.2% for PFOA at pH 5.0 within 5 h, respectively, but a combined system of UV-$Fe^{2+}-S_2O{_8}^{2-}$ dramatically promoted the defluorination efficiency up to 63.3%. The beneficial synergistic behavior between $Fe^{2+}-S_2O{_8}^{2-}$ and UV-$S_2O{_8}^{2-}$ was demonstrated to be dependent on $Fe^{2+}$ dosage, initial $S_2O{_8}^{2-}$ concentration, and solution pH. The decomposition of PFOA resulted in generation of shorter-chain perfluorinated carboxylic acids (PFCAs), formic acid and fluoride ions. The generated PFCAs intermediates could be further defluorinated by adding supplementary $Fe^{2+}$ and, $S_2O{_8}^{2-}$ and re-adjusting solution pH in later reaction stage. The much enhanced PFOA defluorination in the UV-$Fe^{2+}-S_2O{_8}^{2-}$ system was attributed to the fact that the simultaneous employment of UV light and $Fe^{2+}$ not only greatly enhanced the activation of $S_2O{_8}^{2-}$ to form strong oxidizing sulfate radicals ($SO{_4}^{\cdot-}$), but also provided an additional decarboxylation pathway caused by electron transfer from PFOA to in situ generated $Fe^{3+}$.

• 한국표면공학회지
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• 제53권2호
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• pp.59-66
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• 2020

Effects of Na₂SiO₃ concentration added into 0.1 M NaOH + 0.05 M NaF solution on the formation behavior and properties of PEO films on AZ91 Mg alloy were investigated under 1200 Hz of alternating current (AC) by voltage-time curves, in-situ observation of arc generation behavior and measurements of film thickness, surface roughness and micro vickers hardness. In the absence of Na₂SiO₃ in the 0.1 M NaOH + 0.05 M NaF solution, about 4 ㎛ thick PEO film was formed within 1 min and then PEO film did not grow but white spots were formed by local burning. Addition of Na₂SiO₃ up to 0.2 M caused more increased formation voltage and growth of PEO film with uniform generation of arcs. Addition of Na₂SiO₃ from 0.2 M to 0.4 M showed nearly the same voltage-time behavior and uniform arc generation. Addition of Na₂SiO₃ more than 0.5 M resulted in a decrease of formation voltage and non-uniform arc generation due to local burning. PEO film growth rate increased with increasing added Na₂SiO₃ concentration but maximum PEO film thickness was limited by local burning if added Na₂SiO₃ concentration is higher than 0.5 M. Surface roughness of PEO film increased with increasing added Na₂SiO₃ concentration and appeared to be proportional to the PEO film thickness. PEO film hardness increased with increasing added Na₂SiO₃ concentration and reached a steady-state value of about 930 H_V at more than 0.5 M of added Na₂SiO₃ concentration.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2005년도 국제학술심포지움 The 44th Annual Meeting of Korean Society for Life Science
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• pp.23-36
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• 2005

Bax, a mammalian pro-apoptotic member of the Bcl-2 family, induces cell death when expressed In yeast. To investigate whether .Bax expression can induce cell death in plant, we produced transgenic Arabidopsis plants that contained murine Bax cDNA under control of a glucocorticoid-inducible promoter. Transgenic plants treated with dexamethasone, a strong synthetic glucocorticoid, induced Bax accumulation and cell death, suggesting that some elements of cell death mechanism by Bax may be conserved among various orgarusms. Therefore, we developed novel yeast genetic system, and cloned several Plant Bax Inhibitors (PBIs). Here, we report the function of two PBIs In detail. PBIl is ascorbate peroxidase (sAPX). Fluorescence method of dihydrorhodamine123 oxidation revealed that expression of Bax in yeast cells generated reactive oxygen species (ROS), and which was greatly reduced by co-expression with sAPX. These results suggest that sAPX inhibits the generation of ROS by Bax, which in turn suppresses Bax-induced cell death in yeast. PBI2 encodes nucleoside diphosphate kinase (NDPK). ROS stress strongly induces the expression of the NDPK2 gene in Arabidopsis thaliana (AtNDPK2). Transgenic plants overexpressing AtNDPK2 have lower lovels of ROS than wildtype plants. Mutants lacking AtNDPK2 had higher levels of ROS than wildtype. H$_{2O2}$ treatment induced the phosphorylation of two endogenous proteins whose molecular weights suggested they are AtMPK3 and AtMPK6. In the absence of H2O2 treatment, phosphorylation of these proteins was slightly elevated in plants overexpressing AtNDPK2 but markedly decreased In the AtNDPK2 deletion mutant. Yeast two-hybrid and in vitro protein pull-down assays revealed that AtNDPK2 specifically interacts with AtMPK3 and AtMPK6. Furthermore, AtNDPK2 also enhances the MBP phosphorylation activity of AtMPK3 i'n vitro. Finally, constitutive overexpression of AtNDPK2 in Arabidopsis plants conferred an enhanced tolerance to multiple environmental stresses that elicit ROS accumulation In situ. Thus, AtNDPK2 appears to play a novel regulatory role in H2O2-mediated MAPK signaling in plants.

• Journal of Plant Biotechnology
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• 제5권3호
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• pp.143-148
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• 2003

Bax, a mammalian pro-apoptotic member of the Bcl-2 family induces cell death when expressed in yeast. To investigate whether Bax expression can induce cell death in plant, we produced transgenic Arabidopsis plants that contained murine Bax cDNA under control of a glucocorticoid-inducible promoter. Transgenic plants treated with dexamethasone, a strong synthetic glucocorticoid, induced Bax accumulation and cell death, suggesting that some elements of cell death mechanism by Bax may be conserved among various organisms. Therefore, we developed novel yeast genetic system, and cloned several Plant Bax Inhibitors (PBIs). Here, we report the function of two PBIs in detail. PBI1 is ascorbate peroxidase (sAPX). Fluorescence method of dihydrorhodamine123 oxidation revealed that expression of Bax in yeast cells generated reactive oxygen species (ROS), and which was greatly reduced by co-expression with sAPX. These results suggest that sAPX inhibits the generation of ROS by Bax, which in turn suppresses Baxinduced cell death in yeast. PBI2 encodes nucleoside diphosphate kinase (NDPK). ROS stress strongly induces the expression of the NDPK2 gene in Arabidopsis thaliana (AtNDPK2). Transgenic plants overexpressing AtNDPK2 have lower levels of ROS than wildtype plants. Mutants lacking AtNDPK2 had higher levels of ROS than wildtype. $H_2O_2$ treatment induced the phosphorylation of two endogenous proteins whose molecular weights suggested they are AtMPK3 and AtMPK6. In the absence of $H_2O_2$ treatment, phosphorylation of these proteins was slightly elevated in plants overexpressing AtNDPK2 but markedly decreased in the AtNDPK2 deletion mutant. Yeast two-hybrid and in vitro protein pull-down assays revealed that AtNDPK2 specifically interacts with AtMPK3 and AtMPK6. Furthermore, AtNDPK2 also enhances the MSP phosphorylation activity of AtMPK3 in vitro. Finally, constitutive overexpression of AtNDPK2 in Arabidopsis plants conferred an enhanced tolerance to multiple environmental stresses that elicit ROS accumulation in situ. Thus, AtNDPK2 appears to playa novel regulatory role in $H_2O_2$-mediated MAPK signaling in plants.

• 한국식물생명공학회:학술대회논문집
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• 한국식물생명공학회 2003년도 식물바이오벤처 페스티발
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• pp.65-71
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• 2003

Bax, a mammalian pro-apoptotic member of the Bcl-2 family, induces cell death when expressed in yeast. To investigate whether Bax expression can induce cell death in plant, we produced transgenic Arabidopsis plants that contained murine Bax cDNA under control of a glucocorticoid-inducible promoter. Transgenic plants treated with dexamethasone, a strong synthetic glucocorticoid, induced Bax accumulation and cell death, suggesting that some elements of cell death mechanism by Bax may be conserved among various organisms. Therefore, we developed novel yeast genetic system, and cloned several Plant Bax Inhibitors (PBIs). Here, we report the function of two PBIs in detail. PBI1 is ascorbate peroxidase (sAPX). Fluorescence method of dihydrorho-damine 123 oxidation revealed that expression of Bax in yeast cells generated reactive oxygen species (ROS), and which was greatly reduced by co-expression with sAPX. These results suggest that sAPX inhibits the generation of ROS by Bax, which in turn suppresses Baxinduced cell death in yeast. PBI2 encodes nucleoside diphosphate kinase (NDPK). ROS stress strongly induces the expression of the NDPK2 gene in Arabidopsis thaliana (AtNDPK2). Transgenic plants overexpressing AtNDPK2 have lower levels of ROS than wildtype plants. Mutants lacking AtNDPK2 had higher levels of ROS than wildtype. $H_2O_2$ treatment induced the phosphorylation of two endogenous proteins whose molecular weights suggested they are AtMPK3 and AtMPK6. In the absence of $H_2O_2$ treatment, phosphorylation of these proteins was slightly elevated in plants overexpressing AtNDPK2 but markedly decreased in the AtNDPK2 deletion mutant. Yeast two-hybrid and in vitro protein pull-down assays revealed that AtNDPK2 specifically interacts with AtMPK3 and AtMPK6. Furthermore, AtNDPK2 also enhances the MBP phosphorylation activity of AtMPK3 in vitro. Finally, constitutive overexpression of AtNDPK2 in Arabidopsis plants conferred an enhanced tolerance to multiple environmental stresses that elicit ROS accumulation in situ. Thus, AtNDPK2 appears to play a novel regulatory role in $H_2O_2$-mediated MAPK signaling in plants.