• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.24 no.2
• /
• pp.249-260
• /
• 1994

The purpose of this study was to aid in the radiation therapy of head and neck cancer patients. For this study, radiation survival curves were generated for Bl6, MG-63 and YAC-l cell lines using semiautomated MTT assay and Dye Exclusion Assay. Irradiation of 2, 4, 6, 8, 10Gy were delivered at room temperature at a dose rate of 210.2cGy/min using / sup 60/Co γ-ray Irradiator ALOORAOO 8. The viable cells were determined for each radiation dose and compared to control values. The obtained results were as follows: 1. There was significantly different absorbance at 10Gy on B16 cell line in MTT assay(P<0.05). 2. There was significantly different absorbance at 4, 6, 8, 10Gy on MG-63 cell line in MTT assay(P<0.05). 3. YAC-l cell line was more sensitive than B16 or MG-63 cell line to all doses of radiation(P<0.05). 4. There was significantly different absorbance among all tumor cell lines except between B16 and MG-63 cell line at ZGy in MTT assay(P<0.05). 5. Good correlation was obtained between MTT assay and DEA(P<0.05). The efficient of correlation of B16, MG-63 and YAC-l cell line was 0.845, 0.824 and 0.906, respectively.

• Restorative Dentistry and Endodontics
• /
• v.22 no.1
• /
• pp.209-219
• /
• 1997

The research of the dentin bonding system was mainly on the chemistry and bonding strength. And in vitro assessement of biocompatibility of dentin bonding system was not completely developed. The purpose of this study was to evaluate the cytotoxic effect of several dentin primers. Scotchbond Multi-Purpose (3M Dental Products. USA). Gluma (BayerDental. Germany). All-Bond (Bisco. USA). ProBond (CaulkDensply, USA) and VeridonFil (Dongyang Nylon. Korea) were included. Cytotoxicity was tested using MTT cell viability test. 0.5 ul. 1 ul. 2 ul and 10 ul of each primer were added to the 96 well plate of incubated L929 cell lines. After 30-minute. 1. 4. 24 and 72-hour exposures. absorbance of L929 cells was observed with ELISA reader. All data were analyzed using t-test. All primers showed cytotoxicity on L929 cells under every conditions used in this study. Absorbance of L929 cells was decreased by time. Scotch bond group exhibited the lowest absorbance value in all exposure time and value.

• Journal of Wetlands Research
• /
• v.16 no.2
• /
• pp.275-280
• /
• 2014

Because ammonia in water body can cause water pollution as a result of generating ammonium ion, it is of importance in the management of water quality. This work performed to analyze the ammonium ion by measuring the color band length on the basis of modifying the indophenol method. When 1-naphthol was employed as a coloring agent, the maximum absorbance was shown near 720nm, where the proper injection was in the range of 0.5-1.5ml. About 80% of absorbance was observed after the color development was made within the 20 minutes. In the manufacturing of coloring agent, the proper concentration of NaOH was 1.5-2.5M, and the effect of pH on the color development is negligible. In addition, the color development was effectively in the region of room temperature.

• Journal of the Korean Chemical Society
• /
• v.29 no.3
• /
• pp.271-276
• /
• 1985

An anomalous absorbance-temperature profile of calf thymus DNA, having a trough preceding the initiation of the melting, occurs at the spermine concentration, where the DNA collapses into a compact structure. The cooperativity, enthalpy, and the midpoint of the phase transition to the trough region are more sensitive to ethidium bromide than those of the Tm region. As the concentration of ethidium bromide added is increased, the peak size of the trough is decreased, while the Tm remains essentially constant.

• Journal of Environmental Science International
• /
• v.4 no.1
• /
• pp.91-103
• /
• 1995

The reaction rate, equilibrium, and flow injection analysis methods were fundamentally evaluated for the determination of aqueous ammonia. The selected indophenol blue method was based on the formation of indophenol blue in which ammonium ion reacted with hypochlorite and phenol in alkaline solution. In the optimized reaction condition, the reaction followed 1st order reaction kinetics and the final product was stable. The absorbance measurements before and after the equilibrium were utilized for the reaction rate and equilibrium methods. The reaction rate methods, based on the relative analytical signals for the possibility of eliminating interferents, were shown to have good linear calibration curves but the detection limit and the calibration sensitivity were poorer than those in the equilibrium method. The detection limits were 32-49 pub and 24 pub for the reaction rate and equilibrium methods, respectively In the flow injection analysis, the absorbance was measured before the equilibrium reached and thus resulted in 30% reduction of calibration sensitivity. However, the detection limit was 11 ppb, indicating that the peak-to-peak noise for the blank was remarkably improved. Compared to the manual methods, the optimized experimental condition in a closed reaction system reduced the blank absorbance and the inclusion of ammonia from the atmosphere was prevented. In addition, highly reproducible mixing of sample and reagents and analytical data extracted from continuous recording showed excellent reproducibility.

• Journal of Community Nutrition
• /
• v.7 no.4
• /
• pp.215-219
• /
• 2005

Oxygen radical absorbance capacity(ORAC) is known to be a sensitive and simple method to determine total antioxidant capacity(TAC) in biological samples. While TAC has received great attention with its relation to pathogenesis in the progression of several diseases, little is known about association of ORAC with metabolic risk factors. The aim of this study is to evaluate the relationship between ORAC and serum lipid profiles, fasting glucose and anthropometric measures. One hundred seventeen volunteers participated in the study. Perchloric acid treated serum was used to determine $ORAC_{pca}$. Mean$ORAC_{pca}$ of subjects whose serum total cholesterol(TC) concentrations were $\geq$ 200 mg/dl was significantly(P < 0.05) higher than that of subjects whose TC concentrations were < 200mg/dl. There were significantly positive correlations between $ORAC_{pca}$ and serum concentrations of TC(P < 0.05) and low density lipoprotein (LDL) cholesterol(P < 0.01). The positive relation between cholesterol concentrations and $ORAC_{pca}$ in serum may suggest an elevated TAC against oxidative stress associated with the cardiovascular risk factors. (J Community Nutrition 7(4): $215\∼219$, 2005)

• Bulletin of the Korean Chemical Society
• /
• v.16 no.12
• /
• pp.1218-1222
• /
• 1995

The pKa values of benzyltetrahydrothiophenium halides 1a-f in water have been estimated by measuring the absorbances of the solution in aqueous hydroxide ion solution. Assuming that the ratios of the activity coefficients remains close to unity, the absorbance of the solution can be expressed as A/[SH]o=(εSH+εS-K[OH-])/(1+K[OH-]), where A, [SH]o, K, εSH, and εS- are the absorbance of solution, the initial concentration of 1a-f, the equilibrium constant, and the extinction coefficients for SH and S-, respectively. The εS- and K values that best fit with this equation were calculated by a nonlinear regression analysis with a large number of absorbance data determined at different [OH-] and [SH]o. The pKa values of the SH were then calculated with the relationship Ka=-log K+14. The validity of this method has been demonstrated by the excellent agreements between the experimental and literature pKa values of three organic acids. The pKa values of 1a-f estimated by this method are in the range of 12.5-15.3 and correlate well with the Hammett equation. The large negative deviation for the pKa values of 1e and 1f from the Hammett plot has been attributed to the extra hydrogen bonding between the phenyl group and water molecules attracted by the hydrophilic substituents.

• Nuclear Engineering and Technology
• /
• v.55 no.9
• /
• pp.3383-3387
• /
• 2023

A new dyed polyvinyl alcohol (PVA) film dosimeter based on 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MMT) tetrazolium dye is proposed in this study for measuring high gamma radiation dose. Gamma cell irradiator that contains Co-60 gamma-ray source was used to expose the novel MMT-PVA films to different doses up to 25 kGy. The changed in optical property of irradiated and unirradiated films were characterized by UV-Vis spectrophotometer. The results show that the dose sensitive and the linear range of irradiated films were increased considerably with increase of MMT concentration from 1 to 5 mM. The dose response of dyed PVA film changed substantially with changing relative humidity (12-74%) as well as irradiation temperature (10-40 ℃). The absorbance of the unirradiated films does not change up to 10 days in dark while a significant increase in their absorbance was reported for similar films under fluorescent light. The irradiated dosimeters that kept in dark showed a perfect stability for 54 days. It was found that no obvious impact of dose rate on the irradiated MMT-PVA film dosimeters.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.12
• /
• pp.100-105
• /
• 2017

An 8-hydroxyquinoline compound that was synthesized with 8-hydroxyquinoline-2-carboxaldehyde and 4-aminoantipyrine was investigated for use as the sensing material of a fiber-optic copper ion sensor in an aqueous environment. The experiment was conducted with a fiber-optic measurement system, in order to evaluate the relationship between the absorbance peak and copper ion concentration. The synthesized derivative exhibited a (highly selective) chromogenic phenomenon for copper ions among various metal ions in an aqueous environment and showed a specific absorbance peak at a wavelength of 530 nm for copper ions. The effect of mercury ions was investigated to evaluate the selectivity of the prepared synthesized derivatives toward Cu ions. The absorbance was measured at various concentration ratios of Cu and Hg ions (Cu:Hg ratios from 0.05 to 20), and it was found that the absorbance at 530 nm tended to increase with increasing Cu ion concentration. The experimental results also showed the linear relationship between the logarithmic concentration of copper ions and the specific absorbance peak at a wavelength of 530 nm. These results indicate that the synthesized 8-hydroxyquinoline compound has selectivity for copper ions and can be used as a sensing material for fiber-optic copper ion sensors.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.33 no.5
• /
• pp.383-387
• /
• 2000

To investigate availability of color value as quality standard for grading of salt-fermented fish sauces, the effect of storage period, dilution ratios, additives (glucose, MSG, IMP) and pigments (caramel and tar) on the changes of color value were measured by spectrophotomeky. The highest absorbance was scanned at 453 nm in fish sauces (anchovy and northern sand lance) without regard to storage periods, dilution ratios, pigments and additives. Absorbance at 453 nm was gradually increased during storage in fish sauces, and absorbance of northern sand lance sauce was higher than that of anchovy sauce during fermentation. There were almost no differences according to concentration of additives in fish sauces added additives during storage. But in case of fish sauces added pigments, absorbance increase of fish sauces added tar pigment was faster than that of caramel pigment during storage. The results suggest that color value is inadequate as quality standard for grading of salt-fermented fish sauces.