• Bulletin of the Korean Chemical Society
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• 제30권4호
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• pp.825-828
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• 2009

Alum $(KAl(SO_4)_2{\cdot}12H_2O)$ is an inexpensive, efficient, non‐toxic and mild catalyst for the synthesis of bis(indolyl)methanes by the reaction of 1H-indole with various aldehydes/ketones under the influence of ultrasound irradiation in solvent‐free condition. The remarkable advantages of this method are the simple experimental procedures, shorter reaction times, high yields of product and green aspects by avoiding toxic catalysts and solvents.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2367-2374
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• 2013

Lysine (Lys) immobilized on zeolite 4A was prepared by a simple adsorption method. The physical and chemical properties of Lys/zeolite 4A were investigated by X-ray diffraction (XRD), FT-IR, Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis. The obtained organic-inorganic composite was effectively employed as a heterogeneous basic catalyst for synthesis of ${\alpha},{\beta}$-unsaturated carbonyl compounds. No by-product formation, high yields, short reaction times, mild reaction conditions, operational simplicity with reusability of the catalyst are the salient features of the present catalyst.

• Bulletin of the Korean Chemical Society
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• 제27권1호
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• pp.71-76
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• 2006

Porous polymer monolithic columns were prepared by the direct free radical copolymerization of methacrylic acid and ethylene glycol dimethacrylate within the confines of a chromatographic column in the presence of toluene-dodecanol as a porogenic solvent. The separation characteristics of the monolithic columns were tested by a homologous series of xanthine derivatives, theophylline and caffeine. The effects of the polymerization mixture composition and polymerization condition, mobile phase composition, flow rate and temperature on the retention times and separation efficiencies were investigated. The results showed that the selection of correct porogenic solvents and appropriate polymerization conditions are crucial for the preparation of the monolithic stationary phases. The separation efficiency was only extremely weakly dependent on flow rate and temperatures. Hydrogen-bonding interaction played an important role in the retention and separation. Compared with conventional particle columns, the monolithic column exhibited good stability, ease of regeneration, high separation efficiency and fast analysis.

• 한국식품영양과학회지
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• 제32권1호
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• pp.115-118
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• 2003

본 연구는 캠벨종 포도의 종자와 과피 에탄올 추출물의 추출조건과 그에 따른 DPPH법에 의한 free radical 소거 활성을 비교하여 최적의 추출 조건의 확립과 항산화 활성을 살펴보았다. 추출 조건은 추출 용매인 에탄올의 농도와 추출 온도를 달리 하여 각각의 수율을 비교하였으며, 각 분획물은 hexane 분획물, chloroform 분획물, ethyl acetate 분획물, butanol 분획물 및 물 분획물로 나누어, free radical 소거 활성을 RC$_{50}$으로 나타내었다. 추출 수율은 종자에서는 추출 온도 78$^{\circ}C$, 에탄올 농도 100%에서 11.4%로 다른 온도와 농도 조건에 비하여 높은 수율을 나타냈으며, 과피 에서도 역시 추출 온도 78$^{\circ}C$, 에탄올 농도 100%에서 44.5%로 다른 온도와 농도 조건에 비하여 높은 수율을 나타냈다. 각 분획물 중에서는 물 분획물이 종자에서는 39.2%인데 비하여 과피 에서는 85.6%로 다른 분획물에 비하여 많이 차지하였다. DPPH법에 의한free radical 소거 활성에서는 종자의 경우, 5$0^{\circ}C$ 에탄을 추출물이 RC$_{50}$=16.8 $\mu\textrm{g}$/mL로, 분획물에서는 ethyl acetate 분획물이 RC/syb 50/=15.4 $\mu\textrm{g}$/mL로 가장 높은 활성을 나타내었다. 과피의 경우, 78$^{\circ}C$ 에탄올 추출물이 RC$_{50}$=2437.5 $\mu\textrm{g}$/mL로, 분획물에서는 butanol 분획물이 RC$_{50}$=698.4 $\mu\textrm{g}$/mL로 가장 높은 활성을 나타내었다. 이상의 결과를 통하여 추출 온도와 용매 농도에 따른 수율의 차이가 있었으며 free radical 소거 활성에서는 종자 에탄을 추출물이 과피 에탄올 추출물 보다 145배 이상의 현저히 높은 활성을 나타내었다.을 나타내었다.

• 한국식품과학회지
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• 제35권1호
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• pp.121-124
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• 2003

본 연구는 거봉종 포도의 종자와 과피로부터 에탄올용매의 농도와 추출 온도변화에 의한 추출물의 수율의 차이와 그에 따른 free radical 소거 활성을 비교하였다. 각 분획물은 에탄올 추출물로부터 hexane 분획물, chloroform 분획물, ethyl acetate 분획물, butanol 분획물 및 물 분획물로 나누어 free radical 소거 활성을 $RC_{50}$으로 타나내었다. 추출 수율은 종자 및 과피 모두에서 추출 온도 $78^{\circ}C$, 에탄올 농도 100%에서 36.0%와 49.5%로 다른 온도와 농도 조건에 비하여 높은 수율을 나타내었다. 각 분획물 중에서는 물 분획물이 종자에서는 72.1%인데 비하여 과피에서는 92.7%로 다른 분획층에 비하여 많이 차지하였다. DPPH법에 의한 free radical 소거 활성에서는 종자의 경우, $78^{\circ}C$ 에탄올 추출물이 $RC_{50}\;=\;409.7\;{\mu}g/mL$이며, 분획물에서는 ethyl acetate층이 $RC_{50}\;=\;136.7{\mu}g/mL$로 가장 높은 활성을 나타내었다. 과피의 경우, $78^{\circ}C$ 에탄올 추출물이 $RC_{50}\;=\;6528.8\;{\mu}g/mL$로, 분획물에서는 ethyl acetate층이 $RC_{50}\;=\;694.7\;{\mu}g/mL$로 가장 높은 활성을 나타내었으나, 물 분획물은 free radical 소거 활성을 보이지 않았다. 이상의 결과를 통하여 추출온도와 용매 온도에 따른 수율의 차이가 나타났으며 추출온도와 free radical 소거 활성의 효능은 별다른 차이가 없는 것으로 나타났다. 전반적으로, 본 연구 결과 종자 에탄올 추출물과 분획물 모두 과피 추출물보다 현저히 높은 활성을 나타내었다.

• 한국식품영양과학회지
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• 제34권6호
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• pp.755-758
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• 2005

식품 산업에서 발생되는 부산물의 가치를 재고하는데 있어서 머루 종자 에탄올 추출물을 대상으로 free radical 소거 능을 탐색하여 머루종자의 기능성을 찾고자 본 실험을 수행하였다. 그 결과, 추출수율은 에탄을 농도, 추출온도 및 시간에 따라 전반적으로 $4\~12\%$를 나타내었으며 $90\%$ 에탄올로 $70^{\circ}$C에서 12시간 추출한 추출물의 수율은 $11.9\%$로 가장 높았지만 free radical 소거능(RC$_{50}$)은 40.42 $\mu$g/mL로 나타났다. 그러나 70$\%$ 에탄올로 $70^{\circ}C$에서 6시간 추출을 하였을 때 추출수율은 $6.9\%$를 나타냈지 만 $RC_{50}$은 $20.93\mu g/mL$로 가장 높았고 총 페놀 함량도 330.71 mg GAE/g으로 가장 높게 나타났다. 본 연구결과, free radical 소거능이 높을수록 총 페놀 함량이 가장 높은 것으로 나타났으며 머루종자 에탄을 추출물의 free radical 소거능이 총 페놀 함량과 밀접하게 관련이 있는 것으로 나타났다. 한편, $70\%$ 에탄올을 $70^{\circ}C$, 6시간 추출물로부터 유기 용매별로 순차적으로 분획한 결과,추출수율은 폴리 페놀 화합물들을 많이 함유하고 있는 ethyl acetate 분획층에서 약 $8\%$로 높았으며, $RC_{50}$도 ethyl acetate 분획층에서 $8.65\mu g/rnL$로 가장 높았고 총 페놀 함량도 ethyl acetate 분획층에서 636.77 mg GAE/g으로 가장 높게 나타났다.

• Journal of Applied Biological Chemistry
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• 제59권1호
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• pp.75-81
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• 2016

Glutaraldehyde was used as a cross-linking agent for immobilization of purified ${\alpha}$-amylase from Exiguobacterium sp. DAU5. Befitting concentration of glutaradehyde and cross-linking time is the key to preparation of cross-linking chitosan beads. Based on optimized immobilization condition for ${\alpha}$-amylase, an overall yield of 56% with specific activity of 2,240 U/g on chitosan beads and 58% with specific activity of 2,320 U/g on chitosan-carbon beads was obtained. The optimal temperature and pH of each immobilized enzyme activity were $50^{\circ}C$ and 50 mM glycine-NaOH buffer pH 8.5, respectively. Those retained more than 75 and 90% of its maximal enzyme activity at pH 7.0-9.5 and after incubation at $50^{\circ}C$ for 1 h, respectively. In addition, the immobilization product showed higher organic-solvent tolerance than free enzymes. The mode of hydrolyzing soluble starch revealed that the ${\alpha}$-amylase possessed high hydrolyzing activity. These results indicate that chitosan is good support and has broad application prospects of enzyme immobilization.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1675-1680
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• 2014

A peroxopolyoxotungsten-based ionic hybrid was synthesized by anion-change of peroxopolyoxometalate (POM) $PW_4O{_{24}}^{3-}$ with dicationic long-chain alkyl imidazolium ionic liquids. The characterization was conducted by FT-IR, TGA, $^1H$-NMR and CHN Elemental analyses. Its catalytic performance was evaluated by the epoxidation of soybean oil with $H_2O_2$ under solvent-free condition, including testing of organic cations influence, catalytic reusability and reaction conditions. The catalyst was proved to be a highly efficient recyclable catalyst for epoxidation of various vegetable oils with $H_2O_2$, showing high $H_2O_2$ utilization efficiency, high catalytic activity, convenient recovery and good reuse ability.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.1979-1984
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• 2014

We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in $H_2$ and $O_2$ gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance.

• 한국물환경학회지
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• 제18권4호
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• pp.421-433
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• 2002

This study was conducted to develope a simple, rapid and solvent-free solid-phase microextraction(SPME) procedure for extracting three organochlorine, one triazine and nine organophosphorus pesticides from water. The optimal conditions of SPME for analyses of organochlorine pesticides were obtained at $250^{\circ}C$ of desorption temperature, 45 minutes of equilibrium time, pH 6 and NaCl 0% addition using $100{\mu}m$ polydimethylsiloxane fiber and those of triazine and organophosphorus pesticides were obtained at $270^{\circ}C$ of desorption temperature, 60 minutes of equilibrium time, pH 6 and NaCl 0% addition using $100{\mu}m$ polydimethylsiloxane fiber. This method showed good lineality for organochlorine pesticides between 0.0001 and $10{\mu}g/L$ with regression coefficients ranging 0.9986~0.9992 and for triazine and organophosphorus pesticides between 0.01 and $10{\mu}g/L$ with regression coefficients ranging 0.9867~0.9998.