• Journal of Photoscience
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• 제9권2호
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• pp.293-295
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• 2002

The structural stability of bacteriorhodopsin (bR) solubilized by Triton X-100 (TX-100) was studied by measuring the denaturation kinetics in the dark and under illumination, and compared with the structural stability of bR solubilized by octyl-${\beta}$-glucoside (OG). In the dark, bR solubilized by TX- 100 was more stable than bR solubilized by OG. Under illumination, bR solubilized by TX-100 showed light-induced denaturation in the same manner as bR solubilized by OG. These results in the dark well correlated with the experimental results of the visible CD band. Although solubilized bR in the TX-100 concentration range of 2-50 mM showed almost identical positive CD band and did not denature in the dark at 35$^{\circ}$C, the kinetic constant of the photobleaching increased with the increase of TX-100 concentration. These results suggested that photo-intermediates of solubilized bR are destabilized by TX-100 micelles.

• 한국염색가공학회지
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• 제20권6호
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• pp.1-7
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• 2008

The effects of $TiO_2$ contents and UV irradiation treatment on the surface properties of PLA films embedded with $TiO_2$ nanoparticle were investigated. Whereas UV irradiation decreased reflectance of the treated PLA films proportionally with increasing UV energy, the reflectance of PLA/$TiO_2$ films increased with increasing UV energy. The UV irradiation treatment caused PLA/$TiO_2$ blend films more polar as indicated in the generation of new carbonyl group and decrease in zeta potentials, which was more pronounced with the introduction of $TiO_2$. Upon UV irradiation, $TiO_2$ particles appeared on the film surface as observed in SEM images. The PLA/$TiO_2$ blend films showed photocatalytic properties such as photobleaching of methylene blue, deodorization of ammonia and antimicrobial activity in comparison with pure PLA films.

• 한국대기환경학회지
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• 제13권3호
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• pp.207-214
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• 1997

We collected airborne complex mixtures in a industrial area of Yeochun, and examined whether these complex mixtures could affect gap junctional intercellular communication (GJIC) in a cultured WBF-344 rat liver epithelial cells (LEC). Since the reduction of GJIC plays an important role in chemical carcinogenesis, measurement of changes of GJIC is a meaningful method to screen carcinogenicity of these mixtures. High and low volume samples were dissolved in dimethyl sulfoxide (DMSO) and tested. Blank filter extractions were also examined for exclud-ing possible toxicity of filter itself, and TPA (12-O-tetradecanoylphorbol-13-acetate) and DMSO were used as positive and negative control, respectively. When the cells were exposed to samples at concentration below that required to maintain rather than 85% cell viability based on the result of neutral red uptake assay, maximal inhibition of GJIC was observed at 1hr after treatment with both high and low volume samples by scrape-loading dye transfer assay. In fluorescence recovery after photobleaching assay, recovery rates via gap junctions were 33%/min in high volume sample and 62%/min in low volume sample. In together, airborne samples collected in Yeochun inhibited GJIC in a cultured WBF-344 rat LEC. These results suggest airborne samples tested in this experiment may attribute to cause a certain type and degree of cancers in in vivo when exposured for some periods.

• 한국광학회지
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• 제7권4호
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• pp.414-418
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• 1996

광표백 광도파로 자기정렬 전극을 이용하여 전기광학 폴리머 디지탈 광스위치를 제작하였다. 이 광스위치는 파장에 무관하게 동작하고 제작조건에 민감하지 않고 설계가 다양하다는 특성을 갖는다. 또한 광섬유와의 결합 손실이 작고 넓은 대역폭을 갖는 장점이 있다. 스위칭 성능을 향상시킬 목적으로 광표백 시간을 이용하여 광표백 광도파로의 도파모드 분포를 적절하게 조절함으로써 브랜치 영역에서의 모드 결합을 최적화 하였다. 또한 광과 인가 전계의 효과적인 겹침과 점진적으로 테이퍼된 전극을 형성하기 위해 자기정렬전극을 이용하였다. 측정된 누화는 1.32.mu.m와 1.55.mu.m에서 모두 -21dB 이하였고 각 출력포트의 소멸비도 모두 20dB 이상이었다.

• Journal of Photoscience
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• 제5권3호
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• pp.111-120
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• 1998

Sensitized photolysis of two onium borates (diphenyliodoium and dimethylphenacylsulfonium tetrakis(pentafluorophenyl)borate, 1a and 2a , respectively) and cationic photopolymerization of an epoxy monomer by the photolysis were investigate. The onium borates were sensitized by the excited singlet of the athracenes(non-substituted, 9-methyl-and 9, 10-dimethylanthracene) and generated acid by decomposing teemselves. The quantum yields of photobleaching of the anthracenes($\Phi$-AH) and acid generatiion (øacid) by the onium borates were the same order as those of the corresponding onium salts in aerated solutions (methanol and acetoitrile) and in argon(Ar) saturated acetonitrile. However, in the photolysis of the iodonium borates 1a in Ar saturated MeOH , øacid was much higher than the corresponding ø-AH. The acid generated by the photolysis of the onium borates initiated cationic polymerization of an epoxy monomer. The values of both rate of polymerization (Rp) and degree of conversion on the photopolymerization for the iodonium borated 1a were higher than those of the sulfoium borate 2a. In the photopolymerization for the iodonium borate 1a, both the Rp value and the degree of conversinio increased upon the addition of glycerol as a hydrogen donor. It is suggested that the increase of both values may be caused with the increase of øacid by addition of glycerol.

• 한국광학회지
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• 제8권3호
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• pp.245-249
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• 1997

본 논문에서는 모드 결합을 최적화하기 위해 수정된 결합 영역을 갖는 전기광학 폴리머 디지탈 광스위치를 제작하였다. 분기형 도파로는 반응이온식각 방법을 이용하여 만들었다. 그리고, 수정된 결합 영역은 두 광도파로의 분기점에서부터 광파의 진행 방향을 따라 점진적으로 도입하였으며, 소자 제작 이후에 광표백 방법을 이용하여 구현하였다. 분기 영역에서 두 도파로 간의 모드 결합이 최적화 되도록 수정된 결합 영역의 구조와 굴절률 분포를 조절함으로써, 소자의 길이가 고정되어 있는 상태에서 스위칭 성능을 향상시켰다. 측정 결과에 의하면, 구동 전압은 약 30%이상 감소되었으며 누화는 4~6 dB정도 개선되었다.

• 대한의용생체공학회:의공학회지
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• 제33권4호
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• pp.169-176
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• 2012

Tumor cell morphology is closely related to its migratory behaviors. An active tumor cell has a highly irregular shape, whereas a spherical cell is inactive. Thus, quantitative analysis of cell features is crucial to determine tumor malignancy or to test the efficacy of anticancer treatment. We use 3D time-lapse phase-contrast microscopy to analyze single cell morphology because it enables to observe long-term activity of living cells without photobleaching and phototoxicity, which is common in other fluorescence-labeled microscopy. Despite this advantage, there are image-level drawbacks to phase-contrast microscopy, such as local light effect and contrast interference ring. Therefore, we first corrected for non-uniform illumination artifacts and then we use intensity distribution information to detect cell boundary. In phase contrast microscopy image, cell is normally appeared as dark region surrounded by bright halo ring. Due to halo artifact is minimal around the cell body and has non-symmetric diffusion pattern, we calculate cross sectional plane which intersects center of each cell and orthogonal to first principal axis. Then, we extract dark cell region by analyzing intensity profile curve considering local bright peak as halo area. Finally, we calculated the Fourier descriptor that morphological characteristics of cell to classify tumor cells into active and inactive groups. We validated classification accuracy by comparing our findings with manually obtained results.

• 한국응용과학기술학회지
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• 제17권3호
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• pp.158-166
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• 2000

A conductimetric study of foam formed from mixture of the protein, ${\beta}-lactoglobulin$, and the nonioinc surfactant, SML, revealed that their stability was reduced at concentrations of SML in the range $3{\sim}10mM$. The interaction of SML with ${\beta}-lactoglobulin$ was investigated by fluorimetry and a dissociation constant of $0.2{\mu}M$ was calculated for the complex. Surface tension studies confirmed the presence of interaction between the two components and provided evidence for the progressive displacement of ${\beta}-lactogloblin$ from the air/water interface with increasing SML concentration. Experiments using air-suspended microscopic thin liquid films revealed transitions in the chainage characteristics and thickness of the film at SML concentrations below that which resulted in destabilization of the foam. However, measurements of surface mobility of fluorescent-labeled ${\beta}-lactoglobulin$ by a photobleaching method identified that a transition to a mobile system occurred at a SML concentration which correlated with the onset of instability in the disperse phase. The results would indicate that maintenance of the viscoelastic properties of the surface is paramount importance in determining the stability of interfaces comprising mixtures of protein and surfactant.

• 한국수산과학회지
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• 제53권3호
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• pp.361-367
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• 2020

The objective of this study was to investigate the effect of lactic acid bacteria (LAB) fermentation on the antioxidant activity of kelp Saccharina japonica water extract. Three LAB strains that had exhibited superior antioxidant activity in a previous study were selected for the kelp fermentation starter. The antioxidant activity of the fermented extracts was analyzed during fermentation. After 48 h of fermentation, the extract-fermented Lactobacillus plantarum D-11 strains showed the highest antioxidant activity in terms of DPPH (2,2-diphenyl-2-picryl hydrazyl) radical scavenging, ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] radical scavenging, oxygen radical absorbance capacity (ORAC) and fluorescence recovery after photobleaching (FRAP) assay. Furthermore, the analysis of total phenolic and flavonoid contents revealed that the enhanced antioxidant activity was mainly due to the increased antioxidant content from fermentation. Thus, this study suggests that probiotic LAB fermentation is an attractive approach for the development of various kelp fermentation products.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2002년도 국제심포지움
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• pp.59-72
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• 2002

The anticarcinogenic effects of epicatechin(EC) and ginsenoside Rb2(Rb2), which are major components of green tea and Korea ginsen, respectively, were investigated using a model system of gap junctional intercellular communication (GJIC) in WB-F344 rat liver epithelial cells. 12-O-Tetradecanoylphorbol-13-accetate (TPA) and hydrogen preoxide, known as cancer promoters, inhibited GJIC in the epithelial cells as determined by the scrape loading/dye transfer assay, fluorescence redistribution assay after photobleaching, and immunofluorescent staining of connexin 43 using a laser confocal microscope. The inhibition of GJIC by TPA and H2O2 was prevented with treatment of Rb2 or Ec. The effect of EC on GJIC was stronger in TPA-treated cells than in H2O2-treated cells, while the effect of Rb2 was opoosite to that of EC. EC, at the concentration of 27.8$\mu$g/ml, prevented the TPA-induced GJIC inhibition by about 60%. Rb2, at the concentration of 277$\mu$g/ml, recovered the H2O2-induced GJIC inhibition by about 60%. These results suggest that Rb2 and EC may prevent human cancers by preventing the down-regulation of GJIC during the cancer promotion phase and that the anticancer effect of green tea and Korea ginseng may come from the major respective conponents, EC and Rb2.