• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.8
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• pp.1031-1037
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• 2006

The purpose of this study was to investigate the physicochemical characteristics of gamma irradiated-commercial powdery soup under accelerated storage condition $(60^{\circ}C,\;4\;weeks)$. TBA values increased with increment of irradiation dose, but were not affected by storage period. On the other hand, TBA values increased with increment of storage period in non-irradiated sample. pH of irradiated samples decreased as compared with that of non-irradiated sample and significantly decreased as elapse of storage period (p<0.05). Viscosity of irradiated samples significantly decreased as increment of irradiation dose and no significant difference was abserved as elapse of storage period (p<0.05). In Hunter's value, L value decreased but a value and b value were not significantly different with increment of irradiation dose and elapse of storage period. Because gamma irradiation was led to lipid oxidation and decrease in viscosity of commercial powdery soup, these results suggested that further studies should be investigated to reduce detrimental effects induced by irradiation.

• Korean Journal of Food Science and Technology
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• v.48 no.1
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• pp.9-14
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• 2016

Recently, the market for ready-to-use vegetables has increased largely due to consumer demands, which led to the production of minimally-processed frozen crushed garlic products. This study was designed to determine the effect of electron beam irradiation (0-7 kGy) on microbial decontamination, bioactive compounds, and antimicrobial activities of frozen crushed garlic obtained from Korea and China. The microbial counts (total bacteria, yeasts & molds) were reduced from log 3-4 CFU/g to non-detectable levels as a result of irradiation at 4 kGy. Irradiation treatment at 4 kGy did not affect the amount of alliin, allicin, total pyruvate, and total thiosulfinate of crushed garlic, however, this dose induced insignificant changes in antibacterial activities against pathogenic bacteria including Bacillus subtilis, Staphylococcus aureus, Salmonella enteritidis, Vibrio parahaemolyticus, and Yersinia enterocolitica. Therefore, electron beam irradiation less than 4 kGy can be considered suitable to improve the microbial decontamination without altering the biological activity of frozen garlics.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.4
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• pp.273-278
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• 2022

This study evaluates the improved effect of photodynamic therapy (PDT) by subjecting pathogenic bacteria to a combination of 630 nm light-emitting diode (LED) and 5-aminolevulinic acid (ALA). Bacterial suspensions of 1.5×10⁴ cells/mL were diluted and exposed to ALA concentrations of 10, 5, 2.5, 1.25, and 0.625 mg/mL, incubated for 30 minutes, followed by irradiation with 630 nm LED (18 J/cm² ). The non-irradiated P. aeruginosa group and the group administered only LED light averaged 415 and 245 colonies, respectively. Conversely, the PDT group showed an average of 109, 225, 297, and 285 colonies at concentrations of 10, 5, 2.5, and 1.25 mg/mL of ALA. Evaluating the effect on E. faecalis revealed an average of 8,750 and 8,000 colonies in the group that did not receive the control photosensitizer and the group exposed to light alone, respectively. However, an average of 0, 2350, 4825, and 7475 colonies at concentrations of 5, 2.5, 1.25, and 0.625 mg/mL ALA were determined for the PDT groups. In conclusion, better inhibitory effects were observed for E. faecalis than for P. aeruginosa. Moreover, our results validate the possibility of improved PDT efficacy using a combination of ALA and 630 nm LED.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.123-125
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• 2002

Blue light of Cherenkov radiation generated by electrons in transparent substances such as water and acrylic resin is well known generally. If students can easily observe the blue light at school, they may be impressed by the fascinating radiation. Four years ago, management of the Co-60 unit for radiotherapy was transferred to Nagoya University School of Health Sciences from a related hospital. We have examined whether or not the Cherenkov radiation in water from secondary electrons generated by Co-60 gamma-rays can be safely observed by eyes and photographs. First, the Cherenkov radiation in the water tank was led to the corridor outside the irradiation room by a mirror, and observed directly without any effect of the radiation exposure. Second, photographs of the Cherenkov radiation were taken under the conditions consisted of several irradiation fields and pass lengths of gamma-rays in water.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.89-92
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• 2011

Hydrogenated amorphous carbon (a-C:H) films were deposited by plasma enhanced chemical vapor deposition on silicon substrates. a-C:H thin film was irradiated to a typical He-Cd laser to study its emitting properties. The photoluminescence (PL) intensity during the irradiation achieved a maximum value when 2,000 seconds elapsed. Fourier transform infrared measurement revealed a-C:H thin film suffered transformation from a polymer-like to graphite-like phase during laser irradiation. Thermal annealing was done at various temperatures, ranging from room temperature to $400^{\circ}C$ in the atmosphere, to investigate structural changes in a-C:H film by heat generation during the emission. PL intensity of a-C:H thin film increased 1.5 times without apparent structural change, as annealing temperature increased up to $200^{\circ}C$. However, a-C:H film above $200^{\circ}C$ exhibited significant decrease of PL accompanying dehydrogenation. This led to a red shift of the PL peak.

• Journal of Periodontal and Implant Science
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• v.53 no.2
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• pp.120-134
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• 2023

Purpose: We investigated whether repeated irradiation with light-emitting diodes (LEDs) at a combination of 470 nm and 525 nm could suppress the progression of experimental periodontitis. Methods: A experimental periodontitis model was established in the second, third, and fourth premolars of the mandible in beagle dogs for 2 months. The spontaneous progression of periodontitis was monitored under the specified treatment regimen for 3 months. During this period, the animals were subjected to treatments of either plaque control only (control) or plaque control with LED application (test) at 2-week intervals. The clinical parameters included the probing pocket depth (PPD), gingival recession (GR), and the clinical attachment level (CAL). Histomorphometric analysis was performed using measurements of the length of the junctional epithelium, connective tissue (CT) zone, and total soft tissue (ST). Results: There were significant differences in PPD between the control and test groups at baseline and 12 weeks. When the change in PPD was stratified based on time intervals, it was shown that greater differences occurred in the test group, with statistical significance for baseline to 12 weeks, 6 to 12 weeks, and baseline to 6 weeks. There was no significant difference in GR between the control and test groups at any time points. Likewise, no statistically significant differences were found in GR at any time intervals. CAL showed a statistically significant difference between the control and test groups at baseline only, although significant differences in CAL were observed between baseline and 12 weeks and between 6 and 12 weeks. The proportion of CT to ST was smaller for both buccal and lingual areas in the control group than in the test group. Conclusions: Repeated LED irradiation with a combination of 470-nm and 525-nm wavelengths may help suppress the progression of periodontal disease.

• Journal of the Korean Chemical Society
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• v.56 no.1
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• pp.92-101
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• 2012

The degradation of one of the commercially important hydrogel based on acrylic acid and acryl amide, (acrylic acid-co-acryl amide) hydrogels, by means of ultrasound irradiation and its combination with heterogeneous ($TiO_2$) was investigated. 24 kHz of ultrasound irradiation was provided by a sonicator, while an ultraviolet source of 16 W was used for UV irradiation. The extent of sonolytic degradation increased with increasing ultrasound power (in the range 30-80 W). $TiO_2$ sonophotocatalysis led to complete (acrylic acid-co-acryl amide) hydrogels degradation with increasing catalyst loading, while, the presence of $TiO_2$ in the dark generally had little effect on degradation. Therefore, emphasis was totally on the sonolytic and sonophotocatalytic degradation of hydrogels and a synergy effect was calculated for combined degradation procedures (Ultrasound and Ultraviolet) in the presence of $TiO_2$ nanoparticles. $TiO_2$ sonophotocatalysis was always faster than the respective individual processes due to the enhanced formation of reactive radicals as well as the possible ultrasound-induced increase of the active surface area of the catalyst. A kinetics model based on viscosity data was used for estimation of degradation rate constants at different conditions and a negative order for the dependence of the reaction rate on total molar concentration of (acrylic acid-co-acryl amide) hydrogels solution within the degradation process was suggested.

• Journal of Oral Medicine and Pain
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• v.20 no.1
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• pp.53-65
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• 1995

The growth and synthetic activities of fibroblasts are regulated by cytokines and growth factors derived from activated inflammatory cells. Stimulatory effect of low level laser (LLL) radiation on wound healing seems to be in part due to direct stimulatory action on cell proliferation and synthetic activities of fibroblasts. Also indirect stimulatory effect on the fibroblast function through inflammatory or immune cells is another possible mechanism of biostimulatory action of LLL. This study was performed to determine the growth rate of human gingival fibroblasts obtained biopsy and culture, fibroblast cell line, and immune cell line by using $[^3H]-$ thymidine incorporation test. And gene expression pattern was also analyzed by using the DNA probe such as Hsp70, IL-1$\beta$, MIP-1$\alpha$ and actin cDNA. Proliferation rate of gingival fibroblast was increased by LLL irradiation, but no more effect was added by LPS or IL-1$\beta$ pretreatment Enhanced Hsp70 gene expression was found from gingival fibroblasts and fibroblast cell line COS by LLL irradiation., which was not more increased by LPS or IL-1$\beta$ pretreatment. LLL-irradiated promyelcytic cell line HL-60 and macrophage cell line RAW264.7 showed significant stimulatory effect of proliferation rate when compared with respective control. However there were no changes in growth rate of other immune cell tested in this study, such as B cell line WR19n.l and 230, helper T cell line Jurkat and Hut78, cytolytic T cell line CTLL-r8. By LLL-irradiation Hsp70 gene expression was increased in RAW246.7 and HL-60, not in CTLL-R8. And IL-1$\beta$ and MIP-1$\alpha$ gene expression were induced only from LLL-irradiated RAW264.7. These results led us to presume that LLL radiation may affect to the immune cells, especially to macrophage, through which it might promote wound healing process.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.187-193
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• 2015

Deleterious effects of high dose radiation exposure with high-dose-rate are unarguable, but they are still controversial in low-dose-rate. The regulator of G-protein signaling (RGS) is a negative regulator of G protein-coupled receptor (GPCR) signaling. In addition, it is reported that irradiation stress led to GPCR-mediated mitogen-activated protein kinase (MAPK) and phosphotidylinositol 3-kinase (PI3-k) signaling. The RGS mRNA expression profiles by whole body radiation with low-dose-rate has not yet been explored. In the present study, we, therefore, examined which RGS was modulated by the whole body radiation with low-dose-rate ($3.49mGy{\cdot}h^{-1}$). Among 16 RGS expression tested, RGS6, RGS13 and RGS16 mRNA were down-regulated by low-dose-rate irradiation. This is the first report that whole body radiation with low-dose-rate can modulate the different RGS expression levels. These results are expected to reveal the potential target and/or the biomarker proteins associated with male testis toxicity induced by low-dose-rate irradiation, which might contribute to understanding the mechanism beyond the testis toxicity.

• Composites Research
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• v.30 no.6
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• pp.393-398
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• 2017

The shrinkage distribution of a dental composite (Clearfil AP-X, Kuraray, Japan) used for dental restoration was observed using a digital image correlation method. In order to analyze the shrinkage distribution formed during and after light irradiation, digital images were taken with different photographing conditions for each period. Optimal photographing conditions during LED irradiation were obtained through a preliminary experiment in which the exposure time was applied from 0.15 ms to 0.55 ms in 0.05 ms intervals. The DIC analysis results showed that the strain was non-uniform. For the initial 20 s of light irradiation the composite resin shrank to the level of 50~60% of the final curing shrinkage. Such large shrinkage amount of the composite resin lump affected the tensile stress concentration near the adhesive region between the composite resin and the substrate.