• Food Science and Biotechnology
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• 제18권4호
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• pp.978-984
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• 2009

An analytical method for the simultaneous determination of 9 quinolones (QNs) in porcine, chicken, and bovine muscles was developed and validated using liquid chromatography-fluorescence detector (LC-FLD). The samples were extracted using a liquid-liquid extraction (LLE) process. Chromatographic separation was achieved on a reverse phase $C_8$ column with a gradient elution using a mobile phase of 200 mM ammonium acetate buffer (pH 4.5) and acetonitrile (ACN). The proposed method was validated according to the Food and Drug Administration (FDA) guideline for bioanalytical assay procedures. Recoveries of QNs were 83.1-111.9% with relative standard deviations (RSDs) below 15%. Linearity within a range of 30-500 ${\mu}g/kg$ was obtained with the correlation coefficient ($R^2$) of 0.9967-0.9999. The limits of detection (LOD) were 1-16 ${\mu}g/kg$. These values were lower than the maximum residues limits (MRLs) established by the European Union (EU). The present method was successfully applied to determine QNs in edible muscles.

• 한국농공학회논문집
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• 제53권6호
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• pp.121-128
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• 2011

Long-term water treatment performance analysis was conducted for the constructed wetland treating agricultural tailwater. Studied wetland was established in 2001 and operated from June, 2002 to November, 2010. Wetland vegetation cover was shown over 90 % coverage after 2005. According to vegetation development, accumulation of sediment nutrient was observed; Organic Carbon, T-P and T-N. In addition, DO concentration and temperature was decreased in the constructed wetland output. An infiltration rate also significantly decreased due to compaction of wetland soil. A runoff coefficient was increased due to the low infiltration rate after 2005. A T-N, TSS and Chl.a removal rate was maintained constantly. However, the T-P removal rate was slightly decreased along to wetland operation because low DO concentration could increase elution of phosphorus from sediment. After constructing open water, the T-P removal rate was increased. This is because open water could accelerate the reaearation process. Consequently, over three years of vegetation development could be helpful for wetland performance. In addition, DO concentration is important factor to maintain the T-P treatment.

• 청정기술
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• 제19권3호
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• pp.347-350
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• 2013

견운모에 흡착된 니켈이온의 탈착과 재생특성에 관한 연구가 최적의 탈착제로서 선정된 $HNO_3$를 이용하여 수행되어졌다. 견운모에 흡착된 니켈이온의 탈리는 주사전자현미경과 에너지 분산형 X선 분광기에 의해서 확인 되어졌다. 20 mM의 농도에서 니켈이온의 탈착율은 100%였다. 또한, 투입된 흡착제의 양과 탈착제의 부피로서 정의되는 S/L비가 1.0내에서는 니켈이온은 완전히 탈착 되어졌으며 탈착 공정은 60분내에 빨리 일어났다. 마지막으로 재사용된 견운모를 이용하였을 때 4회까지는 니켈이온의 탈착율이 일정하게 유지되었다.

• 한국환경성돌연변이발암원학회지
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• 제9권1호
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• pp.23-32
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• 1989

Chinese hamster ovary (CHO)-K1 cells echibited a differential sensitivity in the process of DNA repair synthesis induced by ethyl methanesulfonate (EMS) or bleomycin (BLM) in relation to cell cycle. Two assays were employed in this study: alkaline elution and unscheduled DNA synthesis. The post-treat-ment with aphidicolin (APC), an inhibitor of DNA polymerase alpha, inhibited DNA repair synthesis induced by EMS in G2 phase, while APC did not show any effect on BLM-induced DNA repair synthesis in all phases. On the other hands, the 2', 3'-dideoxythymidine (ddTTP), an inhibitor of DNA polymerase beta, inhibited DNA repair synthesis induced by EMS or BLM in both of G1 and G2 phases. These results suggested that the involvement of DNA polymerase alpha and beta in DNA repair was dependent on cell stage or used chemical agent.

• BMB Reports
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• 제35권3호
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• pp.306-312
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• 2002

The effects of salts on the biochemical properties of D-amino acid aminotransferase from Bacillus sp. YM-1 have been studied to elucidate both the inhibitory effects of salts on the activity and the protective effects of salts on the substrate-induced inactivation. The results from UV-visible spectroscopy studies on the reaction of the enzyme with D-serine revealed that salt significantly reduced the rate of the formation of the quinonoid intermediate and its accumulation. The kinetic and spectroscopy studies of the reaction with $\alpha$-[$^2H$]-DL-serine in different concentrations of NaCl provided evidence that the rate-limiting step was changed from the deprotonation of the external aldimine to another step(s), presumably to the hydrolysis of the ketimine. Gel filtration chromatography data in the presence of NaCl showed that the enzyme volume was reduced sharply with the increasing NaCl concentration, up to 100 mM. An additional increase of the NaCl concentration did not affect the elution volume, which suggests that the enzyme has a limited number of salt-binding groups. These results provide detailed mechanistic evidence for the way salts inhibit the catalytic activity of D-amino acid aminotransferase.

• 멤브레인
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• 제18권3호
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• pp.214-218
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• 2008

전기방사를 이용하여 polyethersulfone (PES)-bovin albumin serum (BSA) 단백질 친화막을 제조하였으며, 이때 전기방사에 의한 공정상의 문제점을 용해도가 높고, 끓는점이 높은 2,2,3,4,4,4-Hexafluoro-1-butanol (HFB)를 공용매로 사용함으로써 해결하였다. 또한 공용매는 최적의 온도, 습도 범위를 확대시켜줌으로써 친화막의 대량 생산이 용이하리라 생각한다. 제조된 친화막은 biuret test를 통하여 친화막의 색깔이 무색에서 보라색으로 변함으로써 PES 섬유 내 BSA가 존재함을 확인할 수 있었다. 완충용액의 조성 성분 중 dimethyl sulfoxide (DMSO)는 세척과정에서 BSA와 L-tryptophan사이의 해리를 제어함으로써 용출과정에서 비교실험보다 약 5배의 높은 용출량을 보여주었다.

• 대한안전경영과학회지
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• 제16권4호
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• pp.441-449
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• 2014

As people seek a healthy, wealthy, and quality life more than before, interests in mineral water are picking up and the consumption continues to increase accordingly. In an experiment to examine changes in the water quality after mineral water on the market was kept indoor and outdoor for four weeks, there seemed to be no problem in external appearance. Water kept in an outdoor storage contained more odor-savor than water kept in an indoor storage. Odor was not detected in 90% of the sample, and savor not in 80% of it. As for the mechanism of odor-savor generation, the elution of chemical substances from a container may be taken into consideration. In general, odor and savor have turned out to be in close correlation to each other. The average number of bacteria in the sample mineral water was $200{\pm}10CFU/mL$, and such factors as area of storage and ozone post-treatment did not cause significant effects on the reproduction of common microbes. Hence, it is thought that strict regulations on a production process and reduction of the period of circulation will contribute to customers consumption rates.

• Bulletin of the Korean Chemical Society
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• 제28권2호
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• pp.276-280
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• 2007

In this work, caffeine and some catechin compounds + C, EC, EGC, and EGCG were extracted from green tea by using molecular imprinted polymers (MIP) as sorbent materials in a solid-phase extraction (SPE) process known as MISPE (molecular imprinted solid-phase extraction). For synthesis of MIP, caffeine was employed as the template, MAA as the monomer, EGDMA as the crosslinker, and AIBN as the initiator. A solution of caffeine (0.2 mg/mL in methanol) was utilized in the solid extraction cartridges following loading, washing, and elution procedures with acetonitrile, methanol, and methanol-acetic acid (90/10, %v/v) as the solvents, respectively. This solid-phase extraction protocol was applied for the extraction of caffeine and some catechin compounds from green tea. A comparison was made between the results obtained with the MIP cartridges and a traditional C18 reversed-phase cartridge. It was thereupon found that the recovery of caffeine by the MIPbased sorbent used in this work was almost two and four times greater than that by a commercially available C18 material. A quantitative analysis was conducted by high performance liquid chromatography (HPLC) using a C18 column (5 μm, 250 × 4.6 mm) with methanol/water (40/60, %v/v) as the mobile phase at a flow rate of 0.5 mL/min.

• Natural Product Sciences
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• 제22권2호
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• pp.77-81
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• 2016

A reversed-phase high-performance liquid chromatographic method is described for the simultaneous determination of three antibacterial flavonoids, artocarpanone, artocarpin, and cycloartocarpin in ethyl acetate extracts from Artocarpus heterophyllus heartwoods. Separation was achieved using a TSK-gel ODS-80Tm column ($5{\mu}m$, $4.6{\times}150mm$) at $25^{\circ}C$ with a gradient elution system of methanol and water as follows: 0-8 min, 60:40; 8-27 min, 80:20; 27-35 min, 60:40, v/v, at a flow rate of 1 mL/min, and a quantitative UV detection at 285 nm. The method was validated by measuring the key parameters, including specificity, linearity, sensitivity, accuracy, repeatability and reproducibility. A high degree of specificity and sensitivity was achieved. The calibration curves for all three flavonoids showed good linearity with a coefficient of determinations ($R^2$) of ${\geq}0.9995$. The recoveries of the method were from 98-104%, with good reproducibility and repeatability (RSD values of less than 2%) were also achieved. Ethyl acetate was the best solvent for extraction of these three flavonoids using the heat reflux conditions for 1 h. This optimized sample preparation and HPLC method can be practically used for a routine standardization process of the extracts from the A. heterophyllus heartwoods.

• Journal of the Korean Wood Science and Technology
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• 제51권5호
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• pp.321-333
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• 2023

In this study, lignin, a lignocellulosic biomass, was chemically modified to produce polyethyleneimine-grafted lignin (PKL) with maximum hexavalent chromium [Cr(VI)] adsorption capacity. Changes in the physicochemical properties due to the cationization of lignin were confirmed through elemental analysis, Fourier transform infrared spectroscopy, and moisture stability evaluation. Alginate (Alg) beads containing PKL (Alg/PKL) were prepared by incorporating cationic lignin into the Alg matrix to apply the prepared PKL in a batch-type water treatment process. The optimal Alg/lignin mixing ratio was selected to increase the Cr(VI) adsorption capacity and minimize lignin elution from the aqueous system. The selected Alg/PKL beads exhibited an excellent Cr(VI) removal capacity of 478.98 mg/g. Isothermal adsorption and thermodynamic analysis revealed that the Cr(VI) removal behavior of the Alg/PKL beads was similar to that of heterogeneous chemical adsorption. In addition, the bulk adsorbent material in the form of beads exhibited adsorption behavior in three stages: surface adsorption, diffusion, and equilibrium.