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

• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.2
• /
• pp.323-330
• /
• 2004

The purpose of this study was to evaluate the diagnostic validity of early proximal caries lesions using laser fluorescence and whether the detection could be enhanced using a fluorescent dye. Direct visual examination and bitewing radiograph were used for comparison. The subjects of this study were 30 children of $3{\sim}9$ years old. Laser fluorescence and dye-enhanced laser fluorescence(mixed wavelength of 488 and 514 nm) were used and viewed through glasses(excluding wavelength<520 nm). For dye-enhanced laser fluorescence a 0.075% sodium fluorescein dye was applied before examination. Proximal caries lesion of each subject was assessed using visual examination, bitewing radiograph, laser fluorescence, and dye-enhanced laser fluorescence. The results in the three detection methods were compared to the assessment of bitewing radiograph. The results from the present study can be summarized as follows: 1. There was highly correlation(r=0.725-0.911) between the bitewing radiograph and all three detection methods(p<0.05) 2. The reproducibility(kappa value) of the visual examination, laser fluorescence and dye-enhanced laser fluorescence comparing with bitewing radiograph of proximal caries was 0.451, 0.683, 0.772, respectively. There was highest correlation between dye-enhanced laser fluorescence and bitewing radiograph for detection of proximal caries. The results from this study indicated that the dye-enhanced laser fluorescence considered to be accurate and reliable method in detecting proximal caries.

• Analytical Science and Technology
• /
• v.8 no.1
• /
• pp.41-45
• /
• 1995

To analyze mixed rare earth elements quantitatively a nonlinear fitting method was applied to laser induced fluorescence signals. Mixed flourescence signal of two elements, Sm and Eu were resolved independently and determined the concentration of these two elements simultaneously. It was found that detection limit for each element in the mixture was sub-ppb level which was the same as that of the single element sample. Additionally it was found that lifetimes of Sm and Eu extracted from the nonlinear fitting method is the same as in the single element cases.

• Journal of Biosystems Engineering
• /
• v.40 no.4
• /
• pp.335-344
• /
• 2015

Purpose: Soybean growth is adversely affected by environmental stresses such as drought, extreme temperatures, and nutrient deficiency. The objective of this study was to develop a method for rapid measurement of drought stress in soybean plants using a hyperspectral fluorescence imaging technique. Methods: Hyperspectral fluorescence images were obtained using UV-A light with 365 nm excitation. Two soybean cultivars under drought stress were analyzed. A partial least square regression (PLSR) model was used to predict drought stress in soybeans. Results: Partial least square (PLS) images were obtained for the two soybean cultivars using the results of the developed model during the period of drought stress treatment. Analysis of the PLS images showed that the accuracy of drought stress discrimination in the two cultivars was 0.973 for an 8-day treatment group and 0.969 for a 6-day treatment group. Conclusions: These results validate the use of hyperspectral fluorescence images for assessing drought stress in soybeans.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.12
• /
• pp.3743-3748
• /
• 2013

A tetradentate ligand of 2-phenyl-4,6-di(pyridin-2-yl)pyrimidine (L) has been synthesized and its complexes with $ZnI_2$ and CuI have been obtained by hydrothermal method. single crystal X-ray diffraction analysis indicates that ligand L coordinates with Zn(II) ions to form a simple four-coordinate di-nuclear complex, while the complexation of L with Cu(I) constructs a one-dimensional chain polymer. The existence of $I^-$ ion hampers the L to assemble grid-type complexes with Zn(II) and Cu(I). Fluorescence spectra show that the L emits blue fluorescence while its Cu(I) polymer decrease the fluorescence intensity and Zn(II) complex quenches the fluorescence.

• Journal of Korea Multimedia Society
• /
• v.18 no.12
• /
• pp.1445-1452
• /
• 2015

In these days, fluorescent materials such as ICG or 5-ALA is used for the brain surgery. The patients who underwent brain tumor surgery has been increased during last 30 years and the survivorship rate increased 22∼33% in 5 years. Recently, the Fluorescence induction surgery is developed for more safety and improved the resection rate for the glioma in the neurosurgery field. In this study, we proposed fluorescence area detection method for ICG and 5-ALA fluorescence induced surgery using acquired images from image processing. Accuracy was 99.21% from ICG images, and 99.51% from 5-ALA images. Matthews correlation coefficient was 88.67% from ICG images, and 90.49% from 5-ALA images.

• KSBB Journal
• /
• v.14 no.3
• /
• pp.377-379
• /
• 1999

In order to improve the transfection efficiency of CHO/dhfr- cells using cationic lipid, optimal concentrations of the cationic lipid($LipofectAmine^{TM}$) and DNA(pEGFP-C1) need to be determined. The use of green fluorescent protein(GFP) gene as a reporter gene facilitated the quantification of transfection efficiency. The green fluorescence intensity of each cell transfected at various lipid-DNA concentrations was measured using fluorescence-activated cell sorter(FACS) analysis. A combination of $2.0{\mu}L$ cationic lipid and 0.4{$\mu}g$ DNA in a well resulted in the highest trasfection efficiency. Taken together, the method using FACS analysis of GFP is simple and fast, facilitating the optimization of transfection.

• Journal of Dairy Science and Biotechnology
• /
• v.33 no.4
• /
• pp.271-275
• /
• 2015

Colloidal semiconductor CdSe-ZnS core-shell nanocrystal quantum dot (Qdot) are luminescent inorganic fluorophores that show potential to overcome some of the functional limitations encountered with organic dyes in fluorescence labeling applications. Salmonella Enteritidis has emerged as a major cause of human salmonellosis worldwide since the 1980s. A rapid, specific, and sensitive method for the detection of Salmonella Enteritidis was developed using Qdot as a fluorescence marker coupled with immunomagnetic separation. Magnetic beads coated with anti-Salmonella Enteritidis antibodies were employed to selectively capture the target bacteria, and biotin-conjugated anti-Salmonella antibodies were added to form sandwich immune complexes. After magnetic separation, the immune complexes were labeled with Qdot via biotin-streptavidin conjugation, and fluorescence measurement was carried out using a fluorescence measurement system. The detection limit of the Qdot method was a Salmonella Enteritidis concentration of $10^3$ colony-forming units (CFU)/mL, whereas the conventional fluorescein isothiocyanate-based method required over $10^5CFU/mL$. The total detection time was within 2 h. In addition to the potential for general nanotechnology development, these results suggest a new rapid detection method of various pathogenic bacteria from a complex food matrix.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.31 no.3
• /
• pp.356-360
• /
• 1986

The potential of the chlorophyll fluorescence technique in screening eleven rice varieties for chill-sensitivity was assessed by measuring the change in the rate of rise of variable fluorescence (FR) and the maximum yield of variable fluorescence, F$\_$VAR/ (F$\_$MAX/-F$\_$0/) after 8 days chilling at 10$^{\circ}C$. The changes in both fluorescence parameters with chilling agreed well with visual assessments of injury carried out at the end of the chilling period. Furthermore, it was found that in the majority of the rice cultivars tested their chilling sensitivity agreed well with the rate of rise of chlorophyll fluorescence (F$\_$R/) measured at 25$^{\circ}C$. The method of chlorophyll fluorescence was rapid, reproducible, sensitive and non-destructive and it should be a valuable new tool in screening large numbers of closely related rice varieties for chilling sensitivity.

• Nuclear Engineering and Technology
• /
• v.53 no.4
• /
• pp.1297-1303
• /
• 2021

Most thickness measurement techniques using X-ray radiation are unsuitable in field processes involving fast-moving organic films. Herein, we propose a Compton scattering X-ray radiation method, which probes the light elements in organic materials, and a new simple, non-destructive, and non-contact calibration-free real-time film thickness measurement technique by setting up a bench-top X-ray thickness measurement system simulating a field process dealing with thin flexible organic films. The use of X-ray fluorescence and Compton scattering X-ray radiation reflectance signals from films in close contact with a roller produced accurate thickness measurements. In a high-thickness range, the contribution of X-ray fluorescence is negligible, whereas that of Compton scattering is negligible in a low-thickness range. X-ray fluorescence and Compton scattering show good correlations with the organic film thickness (R² = 0.997 and 0.999 for X-ray fluorescence and Compton scattering, respectively, in the thickness range 0-0.5 mm). Although the sensitivity of X-ray fluorescence is approximately 4.6 times higher than that of Compton scattering, Compton scattering signals are useful for thick films (e.g., thicker than ca. 1-5 mm under our present experiment conditions). Thus, successful calibration-free thickness monitoring is possible for fast-moving films, as demonstrated in our experiments.