• Journal of Life Science
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• v.12 no.5
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• pp.584-588
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• 2002

Asymmetric enantioselective resolution system using epoxide hydrolase activity of Aspergillus niger LK was developed and operated for the production of optically pure styrene oxide. Two-phase hollow-fiber reactor system was employed for the enhanced solubility of racemic styrene oxide in organic phase and protection of epoxide hydrolase activity in aqueous phase. For the removal of phenyl-1,2-ethandiol, the inhibitor of epoxide hydrolase, cascade hollow-fiber reactor system was also developed. Chiral (S)-styrene oxide (39 mM in dodecane) could be asymmetrically resolved with high enantiopurity (> 99% ee) using these reactor system.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.321.1-321.1
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• 2013

높은 광흡수 계수를 갖는 Cu(In,Ga)Se2(CIGS) 화합물 박막 소재는 고효율 태양전지 양산을 위해 가장 전도유망한 재료이나 상대적으로 매장량이 적은 In 및 Ga을 사용한다는 소재적 한계가 있다. Cu2ZnSnSe4(CZTSe) 혹은 Cu2ZnSnS4(CZTS)와 같은 Cu-Zn-Sn-Se계 화합물 반도체는 CIGS 내 희소원소인 In과 Ga이 범용원소인 Zn 및 Sn으로 대체된 소재로써 미래형 저가 태양전지 개발을 위해 활발히 연구되고 있는데, 그 화합물 조합에 따라 0.8eV부터 1.5eV까지의 에너지 밴드갭을 갖는 것으로 알려져 있다. 본 연구에서는 열분해법으로 CZTS 나노 입자를 합성하였다. 용매로 Oleylamine을 사용하였는데, $260{\sim}340^{\circ}C$의 온도 범위에서 5시간 30분 동안 CZTS 나노입자를 합성하였고, $300^{\circ}C$에서 5시간 30분~9시간까지 합성하였다. 헥산을 이용하여 원심분리기와 초음파세척기로 용매인 Oleylamine을 제거하였고, 진공오븐에서 건조된 CZTS 분말의 FE-SEM (Field Emission Scanning Electron Microscope), XRD (X-Ray Diffraction), EDS (Energy Dispersive Spectroscopy) 분석 등을 통해 합성온도에 따른 구조적, 화학적 조성 변화를 조사하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.934-940
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• 2012

Antioxidant activities such as reducing power, electron donating ability(EDA) and oxidation stability of Rumex crispus extracts with ethanol were examined, and adsorption of Pb(II) and Cd(II) with dried Rumex crispus powder in aqueous solution was experimented. Extraction yields based on the soluble solid contents ranged 1.9% to 3.0%, and were inversely proportional to solvent ratio but proportional to extraction temperature. Reducing power and EDA were also increased with extraction temperature but decreased with solvent ratio. These were corresponded to 86.4% and 91.0% of ascorbic acid reducing power and EDA, respectively, on 20 folds of solvent ratio and $75^{\circ}C$ Oxidation stability of Rumex crispus extracts on the corn seed oil was 86~91.3% of butylated hydroxytoluene. Pb(II) adsorptivity of Rumex crispus was higher than Cd(II), and adsorption rate of Pb(II) was 88% in 20 ppm concentration and 60min.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.12
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• pp.1622-1626
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• 2008

This study was carried out for the analysis of chemical composition and antioxidative activity of lotus leaf. The lotus leaf contained 63.8% of crude carbohydrate, 16.9% of crude protein, 1.0% crude fat, and 9.3% of crude ash including high amount of calcium (2.2%). The antioxidative effect of several solvents extracts of lotus leaf was investigated. Among them 70% ethanol extract showed relatively higher extraction yield and higher total phenol content as well as the highest electron-donating ability using 1,1-diphenyl-2-picryl hydroxyl.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.04a
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• pp.125.2-126
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• 2003

손바닥 선인장(Opuntia ficus indica var. saboten)은 열대지역 유래의 다년초로서 열매와 줄기를 공복에 갈아 마시면 변비치료, 이뇨효과, 장운동의 활성화 및 식욕증진에 효능이 있으며, 선인장 줄기는 오래전부터 피부질환, 류머티스 및 화상치료에 이용되어 왔다 선인장 열매(prickly pear pulp)는 14.5%의 고형분 함량을 가지고 있으며, 0.21%의 단백질, 0.12%의 지방, 0.44%의 회분, 0.19%의 pectin 이외에 미량의 비타민 A와 C 그리고 여러 종류의 무기질을 포함하고 있다. 선인장 열매로부터 분리된 pectin 성분은 콜레스테롤 수치를 낮추는 효과가 있다고 보고된 바 있다. 본 연구에서는 손바닥 선인장의 소비 확대 방안의 일환으로 손바닥 선인장 열매를 이용한 겔타입 파우치 제품의 개발을 위한 최적의 제조조건을 확립하고자 하였다. 이를 위하여 손바닥 선인장 열매의 추출특성을 반응표면분석에 의해 모니터링하고, 최적조건에서 얻은 추출물을 이용하여 제조한 파우치 제품의 관능적 특성을 검토하였다. 그 결과 가용성 고형분 함량은 추출온도 82.7$0^{\circ}C$, 추출시간 118.98min 및 용매비 24.91 $m\ell$/g일 때 최대값을 나타내었으며, 총페놀성화합물 함량의 최대값은 578.96 $\mu\textrm{g}$/$m\ell$으로 추출온도 89.37$^{\circ}C$, 추출시간 144.77 min 및 용매비 22.81 $m\ell$/g일 때였다. 전자공여능은 추출 온도 97.26$^{\circ}C$, 추출시간 109.30 min, 용매비 19.73 $m\ell$/g일 때 최대값을 나타내었다. 손바닥 선인장 열매의 겔타입 파우치에 대한 관능검사 결과, 최대의 관능점수를 나타내는 배합비는 전반적인 기호도가 3.75점으로 xanthan gum의 함량이 0.11%, 당의 함량이 6.59%, 사과식초의 함량이 1.34%인 것으로 나타났다.

• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.21-30
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• 2007

A multiwavelength spectrophotometric titration method was applied to study protolytic constants of four water-soluble vitamins, folic acid(vitamin B9 or B0), thiamine(vitamin B1), riboflavin(vitamin B2) and pyridoxal (vitamin B6) in binary ethanol-water mixtures at 25oC and an ionic strength of 0.1M NaNO3. The protolytic equilibrium constants, spectral profiles, concentration diagrams and also the number of components has been calculated from the curve fitting of the pH-absorbance data with appropriate mass balance equations by an established factor analysis model. DATAN program was used for determination of acidity constant and SPECFIT program was used for calculation of standard deviations and partial correlation coefficients. A glass electrode calibration procedure based on the four parameter equation pH=α+SpcH+JH+[H+]+ JOH-Kw/[H+] based on the Gran,s plots was used to obtain pH-readings in the concentration scale (pcH). The effect of the solvent on the protolytic constants was discussed.

• The Korean Journal of Food And Nutrition
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• v.14 no.2
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• pp.120-125
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• 2001

The inhibitory effects of xanthine oxidase by the methanol extract and the solvent fractions obtained from persimmon leaves were investigated. The inhibition ratio of xanthine oxidase was 78% by addition of 2.0mg/ml of the methanol extract. Among the solvent fractions, the ethylacetate fraction showed the strongest inhibitory effect against the xanthine oxidase, followed by the hexane fraction. The effect increased with addition of the ethylacetate fraction. At a concentration of 2.0mg/ml of the ethylacetate fraction, 65% of the enzyme activity decreased within 1.0 min of incubation with xanthine oxidase. But the activity of xanthine oxidise did not decrease significantly by the length of the incubation time.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.405-409
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• 1991

The electrochemical behaviors of copper-1-(2-thiazolylazo)-2-naphthol [Cu(II)-TAN] complex in acetonitrile (AN) solution have been investigated by the use of polarography, controlled potential coulometry and UV-Vis spectroscopy. Cu(II)-TAN complex exhibit three reduction waves at -0.91 V, -1.34 V and -1.65 V vs. S.C.E. in acetonitrile solution containing 5.0 ${\times}\;10^{-3}$M tetraethylammonium perchlorate. Every reduction wave is diffusion controlled. The first reduction wave is considerably reversible and this process is attributed to the formation of anion radical. The second reduction process to the dianion is followed by a chemical reaction producing a complex of hydrazo complex. The third reduction process produce Cu(Hg) amalgam and amine compound.

• Journal of the Korean Geosynthetics Society
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• v.22 no.2
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• pp.13-21
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• 2023

Mean sea level has recently been rising due to global warming causing coastal erosion. As Korea is peninsula, the land loss due to coastal erosion is critical. An approach in this study is cementing the coastal area using bacteria, which is called microbially induced carbonate precipitation (MICP). This study tried to see how fresh water and sea water work with MICP as a solvent. Ureolytic activity during the MICP reaction was measured with deionized and sea water. A soil column was prepared to evaluate the strength of MICP-treated sand. Sands were treated by MICP with surface percolation method. As the treatmen t style was different with other conventional methods, several methods were proposed to properly evaluate the MICP-treated sand surface. A micro-scale evaluation was performed to assess the mineral structure treated by different solvents. As results, sea water rendered the ureolytic reaction slower. A needle penetrometer worked well to evaluate the MICP-treated sand surface. This study confirmed the utilization of sea water is feasible as the solvent of MICP.

• Journal of the Korean Chemical Society
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• v.38 no.9
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• pp.695-700
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• 1994

Hydrogenolysis reactions of CFC-113a catalyzed by various heterogeneous catalysts $(Rh/Al_2O_3,\;Pd/C,\;Ni,\;Al_2O_3,\;Active\;carbon)$ were investigated in the liquid and gas phases. In the liquid phase reaction, different catalysts showed different activities, but all catalysts used gave high selectivities toward HCFC-123 over 95%. It was noticeable that the neutral $Al_2O_3$ showed both a high activity and a selectivity in the liquid phase reaction. In the gas phase reaction, transition metals on carbon(Pd/C, Pt/C) were so active for hydrogenolysis of CFC-113a that they even catalyzed the production reaction of overhydrogenated compounds such as $HCFC-133a(CF_3CH_2Cl)\;and\;HFC-143a(CF_3CH_3)$. $Al_2O_3$, which showed the high activity in the liquid phase reaction, did not show a remarkable activity. When $Al_2O_3$ was used in the liquid phase reaction, the hydrogenolysis of CFC-113a proceeded without any side products in THF. However, the same reaction in MeOH produced side products, such as $CH_3OCH_3\;and\;CH_3CH_2OCH_3$ from solvent. Based on this result, including heterogeneous catalysts, it was concluded that the solvent played an important role in the liquid phase reaction.