• Title/Summary/Keyword: Fluorescence measurement

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Measurement of fluorecence decay times of single molecules in solution (용액내 단분자의 형광소멸시간 계측)

  • 고동섭
    • Korean Journal of Optics and Photonics
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    • v.10 no.1
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    • pp.1-4
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    • 1999
  • A confocal microscope system was used to study the bursts of fluorescence photons from single dye molecules excited at 638 nm by a short-pulsed diode laser with a repetition rate of 17 MHz. A red dye, JA22, in ethylene glycol solution was used as a sample. The fluorescence decay curves of single molecules were acquired using a time-correlated single photon counting and analyzed by a maximum likelihood estimator. It was possible to measure the fluorescence decay times with an error probability of 21% at photon number of more than 40 per dye molecule.

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Application of Fluorescence/Scattering Technique to the Measurement of Spray Droplet Size in GDI Injector (직접 분사식 가솔린 인젝터 분무의 입경 측정에 형광/산란광법의 적용)

  • Kwak, Soo-Min;Ryu, Kyeong-Hun;Choi, Bong-Seok;Kim, Duck-Jool
    • Proceedings of the KSME Conference
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    • 2000.11b
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    • pp.353-358
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    • 2000
  • To achieve the requirement for high fuel economy and low emissions, the research for GDI engines is recently very brisk in the whole world. This study was performed to measure distribution of average particle size in non-evaporating spray. The 2-D fluorescence/scattering images of fuel spray were captured simultaneously by visualization system composed of a laser sheet, a doubling prism, optical filters, and an ICCD camera. Using the ratio of the two light intensities, particle size distribution was obtained. The SMD measured by fluorescence/scattering technique was compared with it obtained by PDA. The experimental results show that the spray structure of GDI injector and temporal SMD distribution.

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The Quantitative Characterization of the Dispersion State of Single-Walled Carbon Nanotubes (단일벽 탄소나노튜브의 분산도 정량적 평가)

  • Yoon, Do-Kyung;Choi, Jae-Boong;Kim, Young-Jin;Baik, Seung-Hyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.4
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    • pp.483-489
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    • 2007
  • We have investigated quantitative measurement techniques of the degree of dispersion of single-walled carbon nanotubes (SWNTs). SWNTs were suspended in aqueous media using a sodium dodecyl sulfate (SDS) surfactant. SWNTs with different dispersion states were prepared by controlling the intensity and time of sonication and centrifugation. The laser spectroscopic techniques were employed to characterize the dispersion state; i.e., raman fluorescence and absorption spectroscopic techniques. Raman spectroscopy has been used to probe the dispersion and aggregation state of SWNTs in solution. Individually suspended SWNTs show increased fluorescence peaks and decreased roping peaks at a raman shift 267 $cm^{-1}$ compared with the samples containing bundles of SWNTs. The ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectrum of decanted supernatant samples show sharp van Hove singularity peaks

The Study on Measurement of Relative Conversion Factor in X-ray Image Intensifier (X선영상증배관의 상대변환계수 측정에 관한 검토)

  • Kim, Sung-Chul;Shin, Sung-Ill;Lee, Sun-Sook;Huh, Joon;Kim, Sung-Soo
    • Journal of radiological science and technology
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    • v.20 no.2
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    • pp.28-33
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    • 1997
  • For the Evaluation of X-ray image intensifier, we measured radiation dose at input of I. I., brightness and fluorescence at output of I. I. by using X-ray exposure meter, optometer and fluorescence meter for the relative conversion factor. Especially, by using fluorescence meter, we could easily get relative conversion factor without having regulated machine by JIS. Since using, the quality of image intensifier is going down. Consequently, it needs continuous quality maintenance.

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Chemical changes in resazurin by probiotics and its application for evaluating living bacterial cell counts and their reduction potentials (프로바이오틱스에 의한 레자주린의 화학적 변화와 생균수 및 환원활성 측정에의 적용)

  • Lee, Hyowon;Oh, Yeong Ji;Hong, Jungil
    • Korean Journal of Food Science and Technology
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    • v.53 no.2
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    • pp.204-212
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    • 2021
  • Resazurin, an oxidized blue dye, is reduced to resorufin, showing a peak absorbance change and emitting fluorescence due to the metabolic activity of living cells. In this study, the growth of Lactobacillus rhamnosus GG (LGG) and the redox potential of living probiotic bacteria were evaluated based on changes in the absorbance or fluorescence of resazurin. Fluorescence analysis is a more accurate and sensitive method for quantifying viable LGG than the colorimetric absorbance measurement of resazurin change. Fluorescence measurement could detect LGG of 6.5-9.5 log CFU/mL within 30 min with R2=0.99. No significant effect of further reduction of resorufin to dihydroresorufin by LGG was observed. Various probiotics showed different resazurin-reducing activities, and L. kimchicus had the highest reducing activity among the six probiotics tested. These findings suggests that fluorescence measurement in a resazurin-based assay is useful for analyzing bacterial growth and the redox potential of living probiotics.

In Vivo Measurement of Plant Vitality by the Fluorescence Transient

  • Soonja Oh;Koh, Seok-Chan
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2002.11b
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    • pp.12-12
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    • 2002
  • The chlorophyll fluorescence combined with the O-J-I-P transients were examined in the leaves of the crinum plants (Crinum asiaticum var. japonicum BAK.), in order to satisfy the demand for rapid in vivo measurement of vitality, and to apply easily to approach questions of economical interest concerning the plant vitality. The photosynthetic efficiency, Fv/Fm, of crinum plants dramatically decreased depending on temperature drop in winter. In summer, the Fv/Fm values was lower in day time than at dawn and night, suggesting that photosynthetic efficiency is chronically photoinhibited in day time. In winter, there was no prominent diurnal fluctuations of Fv/Fm values. However, based on the O-J-I-P transient, PI$\_$NO/ and SFI$\_$NO/ dramatically increased at noon in summer, and $\psi$o/(1-$\psi$o) diurnally fluctuated in winter. These results indicated that vitality indexes such as PI$\_$NO/, SFI$\_$NO/ and $\psi$o/(1-$\psi$o) can be used as the indicators for in vivo measurement of environmental stresses.

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In Vivo Measurement of Plant Vitality by the Fluorescence Transient

  • Soonja Oh;Koh, Seok-Chan
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2002.11a
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    • pp.88-95
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    • 2002
  • The chlorophyll fluorescence combined with the O-J-I-P transients were examined in the leaves of the crinum plants (Crinum asiaticum var.japonicum BAK.), in order to satisfy the demand for rapid in vivo measurement of vitality, and to apply easily to approach questions of economical interest concerning the plant vitality. The photosynthetic efficiency, Fv/Fm, of crinum plants dramatically decreased depending on temperature drop in winter. In summer, the Fv/Fm values was lower in day time than at dawn and night, suggesting that photosynthetic efficiency is chronically photoinhibited in day time. In winter, there was no prominent diurnal fluctuations of Fv/Fm values. However, based on the O-J-I-P transient, PI$\_$NO/ and SFI$\_$NO/ dramatically increased at noon in summer, and $\psi$ο/(1-$\psi$ο) diurnally fluctuated in winter. These results indicated that vitality indexes such as PI$\_$NO/, SFI$\_$NO/ and $\psi$ο/(1-$\psi$ο) can be used as the indicators for in vivo measurement of environmental stresses.

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High-speed Three-dimensional Surface Profile Measurement with the HiLo Optical Imaging Technique

  • Kang, Sewon;Ryu, Inkeon;Kim, Daekeun;Kauh, Sang Ken
    • Current Optics and Photonics
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    • v.2 no.6
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    • pp.568-575
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    • 2018
  • Various techniques to measure the three-dimensional (3D) surface profile of a 3D micro- or nanostructure have been proposed. However, it is difficult to apply such techniques directly to industrial uses because most of them are relatively slow, unreliable, and expensive. The HiLo optical imaging technique, which was recently introduced in the field of fluorescence imaging, is a promising wide-field imaging technique capable of high-speed imaging with a simple optical configuration. It has not been used in measuring a 3D surface profile although confocal microscopy originally developed for fluorescence imaging has been adapted to the field of 3D optical measurement for a long time. In this paper, to the best of our knowledge, the HiLo optical imaging technique for measuring a 3D surface profile is proposed for the first time. Its optical configuration and algorithm for a precisely detecting surface position are designed, optimized, and implemented. Optical performance for several 3D microscale structures is evaluated, and it is confirmed that the capability of measuring a 3D surface profile with HiLo optical imaging technique is comparable to that with confocal microscopy.

Real Time Measurement of Protease Activity of Live Uronema marinum (Ciliata: Scuticociliatida) by Fluorescence Polarization Assay

  • Lee Eun Hye;Kwon Se Ryun;Kim Chun Soo;Chung Joon Ki;Lee Hyung Ho;Kim Ki Hong
    • Fisheries and Aquatic Sciences
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    • v.5 no.4
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    • pp.311-313
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    • 2002
  • Proteolytic activity of live Uronema manum was analyzed by fluorescence polarization (FP) technique. Protease activity was measured by a decrease in FP value using fluorescein isothiocynate (FITC)-casein as a protein substrate. The results demonstrated an inverse linear relationship between fluorescence polarization (FP) values and live ciliate concentration over the range $1\times10^4\;to\;2\times10^5$ cells/well. However, the FP values of $10-10^3$ live parasites were not different significantly from that of control. Time-dependent decrease in FP value was shown in the wells containing live U. marinum. In the present study, FP assay had the benefit to provide measurements of substrate hydrolysis by live parasites in real-time, and did not require separations, precipitations, or transfers of reaction mixture.

Development of Image-based Fluorescence Photobleaching Technique for Measuring Macromolecule Diffusion in Biological Porous Medium (생체 다공성 매질에서 분자 확산 측정을 위한 영상 기반 형광 광표백 기법 개발)

  • Lee, Dong-Hee;Lee, Jeong-Hoon;Park, Choon-Ho;Kim, Jung-Kyung
    • Journal of the Korean Society of Visualization
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    • v.7 no.1
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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.