• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1159-1164
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• 2014

A simple, highly sensitive and selective method based on the rhodamine B-covered gold nanoparticle with dual-readout (colorimetric and fluorometric) detection for $\small{L}$-cysteine is proposed. A mechanism is that citrate-stabilized AuNPs were modified with RB by electrostatic interaction, which enables the nanometal surface energy transfer (NSET) from the RB to the AuNPs, quenching the fluorescence. In the presence of $\small{L}$-cysteine, it was used as a competitor in the NSET by the strongly Au-S bonding to release RB from the Au surface and recover the fluorescence, and the red-to-purple color change quickly, which was monitored simply by the naked eye. Under the optimum conditions, the detection limit is as low as 10 nM. The method possessed the advantages of simplicity, rapidity and sensitivity at the same time. The method was also successfully applied to the determination of $\small{L}$-cysteine in human urine samples, and the results were satisfying.

• Journal of Chest Surgery
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• 제31권12호
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• pp.1200-1205
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• 1998

연구목적: 폐암은 protooncogene의 활성화와 종양억제유전인자(tumor suppressor gene)의 비활성화 등 다단 과정에 의하여 발생한다. 치료목적의 완전 절제가 가능하였던 제 IIIA기 비소세포폐암 환자에서 cyclin D1, p53, bcl-2 gene의 변이가 폐암에 미치는 영향을 조사하고자 하였다. 대상 및 방법: 1990년부터 1995년까지 연세의료원에서 치료목적의 완전절제가 가능하였던 stageIIIA 비소세포폐암 환자 100명의 paraffin block과 임상기록을 이용하였다. 각 환자의 조직절편을 labelled streptavidin-biotin method로 immunohistochemical 염색하였고 cyclin D1, p53, Bcl-2 immunostaining을 위한 조직절편들은 immunostaining하기 전 citrate buffer 내에서 10분에서 20분간 microwave oven으로 전처치한 후 cyclin D1은 NCL-cyclin D1-GM으로 p53는 lone DO-7으로 bcl-2는 clone 124로 overnight incubation하였다. 수술 후 평균 추적조사기간은 24.1 개월(range; 2∼84 개월)이었다. 결과: 100예의 폐암 중 56예가 편평상피세포암, 37예가 선암, 5예가 adenosquamous cell carcinoma, 2예가 대세포암이었고 수술 후 5년 생존율은 32.1%이었다. cyclin D1의 양성율은 35 %, p53는 56 %, bcl-2는 17 %였으나 cyclin D1, p53, Bcl-2 단백질 양성 발현과 생존율과의 상관관계는 없었다. 결론: 연구결과 cyclin D1, p53, Bcl-2 단백질 양성 발현이 비소세포폐암 발생기전과 연관되어 있으나 수술 후 예후인자로서는 부적당한 것으로 판단되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.267-270
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• 1998

We measured the dielectric properties with YMnO$_3$ ceramics using solution method based procedure via by citrate. The crystalline phases were determined using XRD. Also we observed morphologies of YMnO$_3$ ceramics using SEM. We proved the structure of YMnO$_3$ ceramics which is hexagonal. But lots of pores were observed the microstructure. It would be considered as volatile organic. The maximum density of YMnO$_3$ ceramics is obtained sintering temperature 135$0^{\circ}C$ and the ratio 0.95/1.05 of Y/Mn. But even though the density we obtained is the highest, that is lower than theoretical density because of remaining organics by citric acid. Dielectric constant and dissipation factor were improved as increasing sintering temperature and the Y/Mn ratio (0.95/1.05)

• Biotechnology and Bioprocess Engineering:BBE
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• 제3권2호
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• pp.96-102
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• 1998

Primary hepatocytes of small animals such as rat and rabbit were often used for the study of extracorporeal liver support systems. Freshly isolated rat hepatocytes form spheroids within tow days when cultivated as suspension in spinner vessels. These spheroids showed enhanced liver specific functions and more differentiated morphology compared to hepatocytes cultured as monolayers However, shear stress caused by continuous agitation deteriorated spheroids gradually. In this work we immobilized spheroids to prolong liver specific activities. First, hepatocyte spheroids were suspended in collagen solution containing calcium chloride and then dropped into alginate solution. A thin layer of calcium alginate was formed around the droplet and then was removed after the inner collagen was gelled by treatment of sodium citrate buffer. Spheroids embedded in collagen-gel bead maintained liver specific functions such as albumin secretion rate longer than hepatocyte spheroids exposed to shear stress. Therefore, we suggest that this immobilization technique may offer an effective long-term hepatocyte cultivation and facilitase the development of a bioartificial liver support device.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.267.1-270
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• 1998

We measured the dielectric properties with YMnO$_3$ ceramics using solution method based procedure via by citrate. The crystalline phases were determined using XRD. Also we observed morphologies of YMnO$_3$ ceramics using SEM. We proved the structure of YMnO$_3$ ceramics which is hexagonal. But lots of pores were observed the microstructure. It would be considered as volatile organic. The maximum density of YMn03 ceramics is obtained sintering temperature 135$0^{\circ}C$ and the ratio 0.95/1.05 of Y/Mn. But even though the density we obtained is the highest, that is lower than theoretical density because of remaining organics by citric acid. Dielectric constant and dissipation factor were improved as increasing sintering temperature and the Y/Mn ratio (0.95/1.05)

• 대한화학회지
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• 제7권4호
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• pp.299-303
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• 1963

A method of the colorimetric determination of titanium has been developed, based on the fact (IV) forms a stable blue complex with methylthymolblue(MTB) which is suitable for spectrophotometric determination of titanium in the concentration range of 0.2 to 22 $\mu$g per ml as $TiO_2$. The determination was carried out in the solution of pH range of 2.6 to 3.6, and the absorbancy of complex was at 600m$\mu$ with Coleman spectrophotometer. Titanium forms a 1:1 complex with MTB, which has a molar absorptivity, $1.1{\times}10^4$ at 600m\mu$. The effects of hydrogen ion concentration, reagent concentration, stability of complex, and hydrolysis were studied. Most of cations do not interfere seriously; however, many of anions such as oxalate, citrate, phosphate, chloride interfere in this determination.

• 미생물학회지
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• 제3권2호
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• pp.15-21
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• 1965

Using the synchronous culture method and the manometric technique, changes in respiratory activities, utilization of some organic acids (succinate, malate, lactate and acetate etc.) and its effect on glucose metabolism in Chlorella cells at different growing stages were measured. 1) Endogenous respiration of the cells was not active at growing stage and was almost constant throughout the early ripening, maturing and division stages. 2) Lactate was utilized as respiratory substrate better than other organic acids tested. Exogenous respiration of glucose was most active at growing and maturing stages and was decreased strikingly at division stage. 3) Succinate and citrate inhibited endogenous and glucose respiration of the cells throughout the all life cycle. 4) Malate and acetate were utilized in the cells at early growing and division stages better, and malate enhanced the glucose respiration while in case of acetate it was depressed. 5) Calcium ion inhibited not only permeability of respiratory substrate but endogenous respiration itself.

• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.3971-3976
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• 2012

A simple method was developed for the analysis of seven stilbene-type fluorescent whitening agents (FWAs) in paper materials by ion-pair reversed-phase high-performance liquid chromatography with fluorescence detection. These stilbene-type FWAs included two disulfonate, two tetrasulfonate, and three hexasulfonate compounds. After optimization of chromatographic conditions, the FWAs were satisfactorily separated using a reversed-phase column (RP-18) with the following isocratic mobile phase: methanol-water (60:40) containing 17.5 mM TBABr and 10 mM citrate buffer (pH = 7.0). The calibration plot was linear in the range from 5 to 500 ng/mL for two disulfo-FWAs and from 1 to 500 ng/mL for the other five FWAs. Precision levels of the calibration curve as indicated by RSD of response factors were 1.2 and 8.1%. Limits of quantitation (LOQ) ranged from 1.2 to 11 ng/mL.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.267.2-267.2
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• 2013

In the citrate reduction method of gold nanoparticle (AuNP) synthesis, pH of the reaction mixture can have a considerable impact on the size and size distribution of AuNPs. In this work, effects of pH variation upon the size and its distribution were examined systematically. As the initial pH was change from 5.5 to 10.5, it showed an optimal pH around 7.5. At this pH, both of the size and the size distribution showed their minimum values, which was verified by transmission electron microscopy and UV-vis spectroscopy. This occurrence of optimal pH was discussed with the results of in situ monitoring pH during the reaction of AuNP synthesis.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2009년도 추계학술대회 초록집
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• pp.239-239
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• 2009

We prepared Au nanoparticles by seed-mediated method and investigated the effects of process variables on the seed-mediated growth of Au nanoparticles. The monodispersed Au seed nanoparticles in the size range from 14.3 nm to 20.3 nm were prepared by the reduction reaction between $HAuCl_4$ and citrate. We added the $HAuCl_4$ precursors with citrates into the Au seed solution and prepared the Au nanoparticles in the size range from 16.8 and 37.8 nm with monodisperse distribution and could control the size of Au nanoparticles by changing the amount of $HAuCl_4$ precursor.