• Journal of the Korean Chemical Society
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• v.26 no.4
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• pp.224-228
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• 1982

The wavelength of chlorophyll-b on the absorbance and fluorescence emission were shifted to the longer depending on the increasing of solvent polarities but fluorescence excitation spectra were not. The presence of chl-b oligomers and monomers were identified by the specra of fluorescence emission. Fluorescence excitation, absorbance and the measurement of its intensities vs. the concentration of n-prOH added to chl-b solution. The calibration curve of chl-b solution were not obeyed to Beer's law in the range of concentrated soln. because of the presence as the oligomers.

• Journal of Plant Biology
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• v.34 no.4
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• pp.303-309
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• 1991

Limitation of photosynthesis in detached Chinese cabbage (Brassica campestris L.) leaves was induced by feeding of mannose (25 mM) for 12 h in the light, and changes in the basic thylakoid functions under this condition were investigated. The acid soluble phosphate contend and CO2 uptake rate was decreased by 66% and 67%, respectively. However, the starch content was increased by 24% compared to those of controls. From the fast induction curves of chlorophyll fluorescence, dark level fluorescence (Fo) slightly increased while intermediate plateau fluorescence level (FI) to peak level fluorescence (Fp) transient was significantly decreased with a slight decrease in the Fo-to-FI transient. This data means that reduction of secondary electron acceptor of PSII (QB) might be more severely inhibited than that of primary electron acceptor of PSII (QA) by decrease in phosphate level. The strong decline of (Fv)m//Fm ratio suggests that efficiency of excitation energy capture by PSII was decreased markedly. The quenching of Fo (qO), an indicator of state transition, was also occurred over the slow induction kinetics of chlorophyll fluorescence. From quenching analysis, fluorescence was dominantly quenched by nonphotochemical quenchings (qE+qT). These results showed that the capture and transfer efficiency of excitation energy to PSII reaction center in thylakoid was decreased with the decline of leaf phosphate level, and that the state transition was occurred during the induction of photosynthesis under these conditions.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.73-76
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• 2007

Photodynamic diagnosis(PDD) is a method to diagnose the possibility of cancer, both by the principle that if a photosensitizer is injected into an organic tissue, it is accumulated in the tissue of a malignant tumor selectively after a specific period, and by a comparison of the intensity of the fluorescence of normal tissue with abnormal tissue after investigating the excitation light of a tissue with accumulated photosensitizer. Since the selection of the wavelength band of excitation light has an interrelation with fluorescence generation according to the selection of a photosencitizer, it plays an important role in POD. This study aims at designing and evaluating light source devices that can stably generate light with various kinds of wavelengths In order to make possible PDD using a photosensitizer and diagnosis using auto-fluorescence. The light source device was a Xenon lamp and filter wheel, composed of an optical output control through Iris and filters with several wavelength bands It also makes the inducement of auto-fluorescence possible because it is designed to generate a wavelength band of 380-400. The transmission part of the light source was, developed to enhance the efficiency of light transmission. To evaluate this light source device, the characteristics of the light output and wavelength band were verified. To validate the capability of this device as PDD the detection of auto-fluorescence using mouse was performed.

• Bulletin of the Korean Chemical Society
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• v.19 no.7
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• pp.747-753
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• 1998

The phoisomerization process of symmetric carbocyanine dyes such as 3,3'-diethyloxadicarbocyanine iodide (DODCI), 3,3'-diethylthiadicarbocyanine iodide (DfDCI), 1,1'-diethyl-2,2'-dicarbocyanine iodide (DDI), 1,1'-diethyl-2,2'-carbocyanine iodide (DCI), and cryptocyanine (1,1'-diethyl-4,4'-carbocyanine) iodide (CCI) have been studied by measuring the steady state and time resolved fluorescence spectra and the ground-state recovery profiles. The steady-state fluorescence spectrum of photoisomer as a function of concentration and excitation wavelength provides the evidence that the fluorescence of photoisomer is formed by the radiative energy transfer from the normal form and the quantum yield for the formation of photoisomer is increased by decreasing the excitation wavelength. The fluorescence decay profiles have been measured by using the time correlated single photon counting (TCSPC) technique, showing a strong dependence on the concentration and the detection wavelength, which is due to the formation of excited photoisomers produced either by the radiative energy transfer from the non-nal form or by absorbing the 590 nm laser pulse. We first report the fluorescence decay time of photoisomers for these cyanine dyes. The experimental results are explained by introducing the semiempirical calculations. The ground state recovery profiles of DTDCI, DDI, and CCI normal forms have been measured, showing that the recovery time from the singlet excited state is similar with the fluorescence decay time.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.2
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• pp.59-64
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• 2019

In this paper, we introduced a near-infrared multi-channel fluorescence imaging system and analyzed the effects of measurements variables such as exposure time, working distance and intensity of excitation light. Fluorescence signal is increased as exposure time becomes longer, excitation light intensity increases or working distance becomes smaller. Furthermore, the proper composition of optical filters and precise packaging of the imaging modules prevent the increase of background signal. Thus, we confirmed an increase in SBR. Based on the result of this research, we proposed a method to use a multi-channel fluorescence imaging system.

• Journal of Photoscience
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• v.1 no.1
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• pp.75-82
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• 1994

General features of the fluorescence depolarization are briefly reviewed. Molecular rotations and electronic excitation transports are considered to account for the fluorescence depolarization. Various molecular systems studied by the fluorescence depolarization are described. The FiSrster theory which forms a basis for the energy transfer is revisited. Several theoretical treatments for the fluorescence depolarization in liquid and solid phases such as classical hydrodynamics, probability distribution function, Green's function formalism, molecular dynamics simulation and Monte Carlo methods are introduced.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.223-228
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• 2006

High-performance liquid chromatography(HPLC) and fluorescence derivatization were applied for a trace-level N-nitrosodimethylamine(NDMA) analysis of water samples. Fluorescence intensity was optimized with the excitation wavelength of 340 nm and the emission wavelength of 530 nm. pH adjustment after denitrosation was necessary to get a maximum intensity at pH between 9 and 12. Maximum intensity was found with a dansyl chloride concentration of 330 to 500 mg/L. Percentile error in the water sample analyses through solid phase extraction was 12-162% and 6-23% for the lower concentration level(10-200 ng/L NDMA) and the higher level(100-1000 ng/L NDMA), respectively, showing more discrepancy in lower level. However, the average ratios of estimated NDMA to the standard NDMA were close to 1 for both concentration ranges, presenting this HPLC method could detect from tens to hundreds nanograms NDMA per liter. Accurate determination of NDMA, which was injected to a wastewater effluent, revealed the selectivity of fluorescence derivatization for the target compound(NDMA) in the presence of complex interfering compounds. The HPLC with fluorescence derivatization may be applicable for determining NDMA of water and wastewater samples fur various research purposes.

• BMB Reports
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• v.40 no.5
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• pp.644-648
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• 2007

Exposure of algae or plants to irradiance from above the light saturation point of photosynthesis is known as high light stress. This high light stress induces various responses including photoinhibition of the photosynthetic apparatus. The degree of photoinhibition could be clearly determined by measuring the parameters such as absorption and fluorescence of chromoproteins. In cyanobacteria and red algae, most of the photosystem (PS) II associated light harvesting is performed by a membrane attached complex called the phycobilisome (PBS). The effects of high intensity light (1000-4000 ${\mu}mol$ photons $m^{-2}s^{-1}$) on excitation energy transfer from PBSs to PS II in a cyanobacterium Spirulina platensis were studied by measuring room temperature PC fluorescence emission spectra. High light (3000 ${\mu}mol$ photons $m^{-2}s^{-1}$) stress had a significant effect on PC fluorescence emission spectra. On the other hand, light stress induced an increase in the ratio of PC fluorescence intensity of PBS indicating that light stress inhibits excitation energy transfer from PBS to PS II. The high light treatment to 3000 ${\mu}mol$ photons $m^{-2}s^{-1}$ caused disappearance of 31.5 kDa linker polypeptide which is known to link PC discs together. In addition we observed the similar decrease in the other polypeptide contents. Our data concludes that the Spirulina cells upon light treatment causes alterations in the phycobiliproteins (PBPs) and affects the energy transfer process within the PBSs.

• Journal of the Korean Chemical Society
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• v.26 no.4
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• pp.218-223
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• 1982

The absorbance and fluorescence yields of chl-a vs. concentration of n-prOH in diethyl ether, benzene and iso-octane were shown the characteristic point which chl-a structures are changed to monomer by the solvation of oligomer, and the spectral differences of fluorescence excitation between oligomer and monomer were identified by fluorimetry. All the maximum wavelength of absorbance, fluorescence excitation and fluorescence emission were shifted to longer wavelength. The ratios of soret/red band were depended on the band intensions and the polarities of solution in organic solvents mixed with n-prOH.

• KSBB Journal
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• v.16 no.6
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• pp.609-613
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• 2001

New protein-based biosensors using fluorescence for the detection heavy metal ions were developed. The detection range of heavy metal ions was between 10$\^$-3/ mM - 1 mM using casein and albumin as a transducer of biosensor, respectively. Casein showed better results for detecting heavy metal ions than albumin. Simple assay method was developed for the selective analysis of the two heavy metal ions by the fluorescence at wavelength of excitation and emission. This method was successfully applied to determining the concentrations Of Co$\^$2+/ and Fe$\^$3+/.