• Journal of Photoscience
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• 제9권2호
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• pp.296-298
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• 2002

Irreversible photobleaching of bacteriorhodopsin (bR), namely denaturation induced by illumination of visible light, was investigated by absorption kinetic measurements. The denaturation kinetics revealed that light illumination significantly enhanced the structural decay of bR. The kinetic analyses showed that the molecular structure of bR denatures according to a single-exponential decay, whereas irreversible photobleaching has two decay components. The decay constant of the slow component of photobleaching is almost same as that in the dark. An Arrhenius plot of the denaturation kinetic constants for the fast and slow components showed similar activation energies of approximately 19 kcal/mol.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.176-176
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• 2006

We designed and synthesized new type of nonchemically amplified polymeric and molecular resists and studied their lithographic performance. The polymeric resists [poly(DOBEMA-co-GBLMA)] show very high degree of photobleaching at 248 nm and moderate to good degree of photobleaching at 193 nm. The molecular resist (CDEOPE-POSS) shows high degree of photobleaching at 248 nm and modetate degree of photobleaching at 193 nm. CDEOPE-POSS possesses very high oxygen reactive ion etching resistance, which makes it suitable to be used as a bilayer resist. The lithographic studies of these resist materials suggest the feasibility of these materials to be used as single and bilayer resists.

• Current Optics and Photonics
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• 제6권1호
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• pp.86-91
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• 2022

Two-photon fluorescence microscopy was performed on the enamel-dentin junction area of a human tooth using a femtosecond pulsed laser. We obtained a clear image contrast between the bright dentin and dark tubules with the autofluorescence generated from the endogenous fluorophores in dentin. The autofluorescence shows a broad spectrum due to complex cross links between dentinal collagens, which extend from blue to orange wavelengths (470-590 nm), but a gradual autofluorescence loss in photobleaching was observed for a long-term exposure under strong excitation. For increasing excitation power, we found that two-step decay becomes significant in the spectrally integrated autofluorescence.

• 한국가시화정보학회지
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• 제7권1호
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• pp.9-13
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• 2009

Fluorescence recovery after photobleaching (FRAP) has been widely used for the measurement of molecular diffusion in living cells and tissues. We developed an image-based FRAP (iFRAP) technique using a modified real-time microscope and a 488 nm Ar-ion laser. A fractional intensity curve was obtained from the time-lapse images of fluorescence recovery in the bleached spot to determine the diffusion coefficient of fluorescently labeled macromolecules in porous medium. We validated iFRAP through experiments with agar gels (0.5% and 1.5% w/v) containing FITC-Dextrans (10, 70 and 500 kDa MW). Further validation was performed by a Monte Carlo approach, where we simulated the three-dimensional random walk of macromolecules in agar gel model. Diffusion coefficients were deduced from the mean square displacement curves and showed good agreements with those measured by iFRAP.

• 폴리머
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• 제28권6호
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• pp.545-550
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• 2004

광조사에 의하여 발색단 분해를 유도함으로써 고분자의 굴절률을 변화시켜 공중합체 박막의 굴절률을 조절하고, FTIR과 UV/Vis 분광 실험으로 굴절률에 영향을 미치는 구조의 변화를 조사하였다. 광표백에 따라 공중합체 박막의 굴절률이 작아지는 것은 광반응에 의하여 발색단 내 C=C 이중결합이 끊어져 고분자의 편극률이 작아지기 때문이다. 입사되는 빛의 전기장 방향에 의존하는 선택적인 광반응에 의하여 필름 면에 평행한 방향으로 존재하는 발색단이 먼저 분해가 되면서 고분자 필름 면에 평행한 방향의 굴절률이 수직한 방향에서 보다 더 급격하게 감소하였다. 이와 같은 고분자 박막 내의 굴절률 차이를 편광 ATR-FTIR 실험에서 얻어지는 고분자 특성 피크의 변화를 조사하여 증명하였다.

• 한국작물학회지
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• 제30권1호
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• pp.1-6
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• 1985

Burley종 잎담배 건조시 광질별에 따른 백화엽 발생 정도를 밝혀서 차광재료의 개발 및 백화엽 발생방지를 위하여 투명비닐 하우스에 8가지의 유색비닐을 피복하고, 여기에 수확 후 건조과정별로 잎담배를 처리하였다. 또한 자외선과 적외선의 단독 영향을 보기 위하여 1.2$\times$l.2$\times$l.2m 상내의 70cm높이에서 각각 조사하였던 바 그 결과는 다음과 같다. 1. 백화엽 발생은 엽분별로 하엽>중엽>본엽 순으로 하위엽일수록 발생량이 많았다. 2. 백화엽은 중골건조 이후부터 발생되었으며 중골건조 20일 후에는 투명비닐하우스에서 50% 정도가 발생되었 다. 3. 유색비닐 하우스별 백화엽 발생은 그 차이가 없이 모든 유색비닐에서 10% 미만으로 거의 발생되지 않았다. 4. 태양광 의한 유색비닐의 색상 안정도는 흑색=백색>황색>적색비널 순으로 컸으나 적색비닐은 탈색되고 갈라져서 여름의 강광하에서는 2개월 이상 유지 보존이 어려웠고. 백색비닐도 탈색은 되지 않았으나 내구성이 약하였다. 5. 유색비닐 중 흑색비닐에 가까울수록 건조기간이 길었고 건엽 색상은 약간 검었으나 품질은 차이가 없었다. 6. 자외선은 투명비닐에서 대부분 투광되었으나 유색비닐에서는 거의 차광되었고 그 차는 뚜렷하지 않았다. 7. 백화엽 발생은 주로 자외선에 의하여 발생되었고, 적외선은 거의 영향을 미치지 않는 것으로 보였다.

• 한국광학회:학술대회논문집
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• 한국광학회 1999년도 제16회 광학 및 양자전자 학술발표회Proceedings of 16th Optics and Quantum Electronics Conference, 1999
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• pp.108-109
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• 1999

• Journal of Photoscience
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• 제9권2호
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• pp.299-301
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• 2002

Recent denaturation experiments of bacteriorhodopsin (bR) in the dark and under illumination at high temperatures revealed that irreversible thermal bleaching occurs above ~ 70°C and the preceding reversible structural changes in the dark above 60°C are closely related to irreversible photobleaching observed in the same temperature range (Yokoyama et al. (2002). J Biochem. 131,785). In this study, structural properties of bacteriorhodopsin (bR) at high temperatures were extensively probed by hydroxylamine reactivity with the Schiff base in the dark and hydrogen-deuterium (H-D) exchange in the peptide groups. In the Arrhenius plot from kinetics measurements of the hydroxylamine reaction, a good linear relationship between the reaction time constant and the inverse of the absolute temperature was observed below 60°C, while significant increase started above 60°C, suggesting that remarkable increase in water accessibility of the Schiff base in the temperature region. FT-IR spectroscopic studies on the H-D exchange suggested increase in the deuterium exchanges rate of the peptide hydrogen in the same temperature region.

• Journal of Ginseng Research
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• 제14권3호
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• pp.416-420
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• 1990

Ultrastructural and anatomical features of the leaf were studied in Panax ginseng C.A. Meyer(ginseng). The ginseng leaf poorly developed palisade tissue and the size of mesophyll cell was larger and the chloroplast density was lower than that of Glycine max (soyben). Ginseng chloroplast was filled with highly stacked grana and condensely-arrayed thylakoid, so the stroma space was hardly absorbed. However, ginseng mesophyll tissue and chloroplast array did not reduce light energy entering the mesophyll chloroplast, and the high LHCP/CP ratio of ginseng thylakoid resulted in the absorption of excess photon. It is reasonable to assume that 1O1-photogenearation by excess light energy partially resulted from the anatomical and ultrastructural characteristics of the ginseng leaf.

• Journal of Ginseng Research
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• 제15권2호
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• pp.139-143
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• 1991

This study investigated the relations between the photosynthetic rate and the activities of antioxidatile enzymes, glutathione reductase, ascorbate free radical reductase, ascorbate peroxidase, glutathione peroxidase, and ascorbate oxidase, in the leaves of Panax ginseng. Under the normal cultivation condition, Panax in showed lower g1utathione reductase and ascorbate free radical reductase activities the Glycine max. But P ginseng showed higher 91utathione Peroxidase, ascorbate Peroxidase, and ascorbate oxidase activities than C. Panax. Therefore, P. ginseng showed weak activities of reductases for the reduction of the oxidized antioxidants. Under the light intensity of 25 KLux, the reductases showed a decrease of over 75% after 24 hours. But the peroyoxidases decreased about 40%. These results showed that the decrease of reductases acitivities was consistent with the decrease of photosynthetic rate. Therefore, we consider that the regulation of antioxidative enzymes or the application of exogenous antioxidants will be effective means for the protection of photodamage in p. ginseng.