• Food Science and Preservation
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• v.30 no.5
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• pp.729-742
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• 2023

The consumption of king oyster mushrooms has steadily increased owing to their unique flavor and delicate texture. This study extended the storage period of king oyster mushrooms (Pleurotus eryngii ) via gamma irradiation. Irradiated samples (0, 0.5, 1, 2, and 3 kGy) were stored at 4℃ with 80% relative humidity for up to 28 days, and the experiments were conducted every 7 day. Microbiological analysis revealed a dose-dependent reduction in total aerobic bacteria, Pseudomonas spp., and yeasts and molds, and gamma irradiation above 2 kGy effectively controlled microbial contamination for up to 28 days. At the 28th day of storage, the irradiated king oyster mushrooms exhibited delayed browning through the reduction of tyrosinase activity. Moreover, firmness reduction (%) was 80.59±1.89% for the non-irradiated group and 42.80±1.28, 34.57±1.13, 31.05±3.24, and 39.73±0.94% for the irradiated group (0.5, 1, 2, and 3 kGy), respectively. These results were supported by the scanning electron microscopy photos, which showed smaller pores in the irradiated group than in the non-irradiated group. This study demonstrated that 2 kGy of gamma irradiation effectively reduces microbial contamination and delays the browning and softening of king oyster mushrooms for up to 28 days.

• Journal of Microbiology and Biotechnology
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• v.21 no.6
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• pp.574-581
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• 2011

A Gram-positive bacterium was isolated from the saline soils of Jangpura (U.P.), India, and showed high-level of radiation-resistant property and survived upto 12.5 kGy dose of gamma radiation. The 16S rDNA sequence of this strain was examined, identified as Bacillus sp. strain HKG 112, and was submitted to the NCBI GenBank (Accession No. GQ925432). The mechanism of radiation resistance and gene level expression were examined by proteomic analysis of whole-cell extract. Two proteins, 38 kDa and 86.5 kDa excised from SDS-PAGE, which showed more significant changes after radiation exposure, were identified by MALDI-TOF as being flagellin and S-layer protein, respectively. Twenty selected 2-DE protein spots from the crude extracts of Bacillus sp. HKG 112, excised from 2- DE, were identified by liquid chromatography mass spectrometry (LC-MS) out of which 16 spots showed significant changes after radiation exposure and might be responsible for the radiation resistance property. Our results suggest that the different responses of some genes under radiation for the expression of radiation-dependent proteins could contribute to a physiological advantage and would be a significant initial step towards a fullsystem understanding of the radiation stress protection mechanisms of bacteria in different environments.

• KSBB Journal
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• v.26 no.2
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• pp.177-181
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• 2011

This study was conducted to investigate the effects of gamma irradiation on the change of volatile flavor compounds of raw oyster and its cooking drips using headspace methods. Major volatile flavor compounds of the raw oyster were identified as methylthiomethane and 1,5-hexadiene. When the raw oyster was irradiated at the dose of 5 kGy, 1-pentane was newly detected. On the other hand, 9 compounds including N-methoxyformaldehyde were identified as the major volatile compounds of cooking drips from oyster. Among them, N-methoxyformaldehyde contents in cooking drip was decreased by the gamma irradiation. By the gamma irradiation above 30 kGy, new heterocyclic compounds was found in oyster cooking drips. Therefore, the amount of volatile flavor compounds in the raw oyster and cooking drips were changed by gamma irradiation, and these results could be potentially used in the seasoning industry.

• Progress in Medical Physics
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• v.28 no.4
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• pp.149-155
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• 2017

Radiotherapy patients should maintain their treatment position as patient setup is very important for accurate treatment. In this study, we evaluated patient setup error quantitatively according to Cone-Beam Computed Tomography (CBCT) Gamma Density Analysis using Mobius CBCT. The adjusted setup error to the $QUASAR^{TM}$ phantom was moved artificially in the superior and lateral direction, and then we acquired the CBCT image according to the phantom setup error. To analyze the treatment setup error quantitatively, we compared values suggested in the CBCT system with the Mobius CBCT. This allowed us to evaluate the setup error using CBCT Gamma Density Analysis by comparing the planning CT with the CBCT. In addition, we acquired the 3D-gamma density passing rate according to the gamma density criteria and phantom setup error. When the movement was adjusted to only the phantom body or 3 cm diameter target inserted in the phantom, the CBCT system had a difference of approximately 1 mm, while Mobius CBCT had a difference of under 0.5 mm compared to the real setup error. When the phantom body and target moved 20 mm in the Mobius CBCT, there are 17.9 mm and 13.5 mm differences in the lateral and superior directions, respectively. The CBCT gamma density passing rate was reduced according to the increase in setup error, and the gamma density criteria of 0.1 g/cc/3 mm has 10% lower passing rate than the other density criteria. Mobius CBCT had a 2 mm setup error compared with the actual setup error. However, the difference was greater than 10 mm when the phantom body moved 20 mm with the target. Therefore, we should pay close attention when the patient's anatomy changes.

• Journal of Radiation Industry
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• v.6 no.3
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• pp.257-265
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• 2012

This study was carried out to evaluate growth, morphological characteristics, and sugar content among fifty six blackberry (Rubus fructicosus) genotypes derived from gamma-ray treatment (fifty two lines), MNU treatments (three lines), and cross breed R. fructicosus${\times}$R. parvifolius(one line). While 56 genotypes had similar stem diameter with origin variety, the most of mutants showed reduced leaf size. Also, they showed a wide range of variation in fruit size and one hundred fruit weight compared with origin variety. In fruit size and sugar content, two mutant lines showed large fruit sizes and ten mutant lines showed 20% higher sugar content than the original variety. In the correlation analysis, positive relationships were determined between sugar content and stem diameter, fruit length, leaf wide and fruit length/fruit wide ratio. However, leaf length/leaf wide ratio showed a negative correlation with sugar content. The results will be used as fundamental data for Rubus fructicosus breeding program.

• Journal of Radiation Industry
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• v.6 no.2
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• pp.147-152
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• 2012

Anthocyanins are major plant pigment and produced through phenylpropanoid pathway. In this study, anthocyanin biosynthesis mechanisms of chrysanthemum flowers were studied using 'Argus' and flower color mutant 'ARTI-purple' which were induced by 40 Gy gamma irradiation ($Co^{60}$). And, three chrysanthemums, 'Ford', 'Yeonja' and 'Orando' were additionally used as the check varieties to understand the relationship between flower color and expression patterns of genes. The expression patterns of the anthocyanin biosynthetic genes were matched with the flower color of the check varieties. High anthocyanin concentration of 'Orando' showed the high expression of anthocyanin biosynthetic genes. In the white flower of 'Ford', expressions of CHI, DFR and ANS were not identified. Despite different flower color, 'Argus' and 'ARTI-purple' showed different expression patterns compared with the check varieties. From the dot blot analysis, we screened the seven genes showing the different expressions between 'Argus' and 'ARTI-purple'.

• Progress in Medical Physics
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• v.33 no.4
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• pp.150-157
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• 2022

Purpose: Elekta synergy^® was commissioned in the Seoul National University Veterinary Medical Teaching Hospital. Recently, Chung-Ang University Gwang Myeong Hospital commissioned Elekta Versa HD^TM. The beam characteristics of both machines are similar because of the same Agility^TM MLC Model. We compared measured beam data calculated using the Elekta treatment planning system, Monaco^®, for each institute. Methods: Beam of the commissioning Elekta linear accelerator were measured in two independent institutes. After installing the beam model based on the measured beam data into the Monaco^®, Monte Carlo (MC) simulation data were generated, mimicking the beam data in a virtual water phantom. Measured beam data were compared with the calculated data, and their similarity was quantitatively evaluated by the gamma analysis. Results: We compared the percent depth dose (PDD) and off-axis profiles of 6 MV photon and 6 MeV electron beams with MC calculation. With a 3%/3 mm gamma criterion, the photon PDD and profiles showed 100% gamma passing rates except for one inplane profile at 10 cm depth from VMTH. Gamma analysis of the measured photon beam off-axis profiles between the two institutes showed 100% agreement. The electron beams also indicated 100% agreement in PDD distributions. However, the gamma passing rates of the off-axis profiles were 91%-100% with a 3%/3 mm gamma criterion. Conclusions: The beam and their comparison with MC calculation for each institute showed good performance. Although the measuring tools were orthogonal, no significant difference was found.

• The Plant Pathology Journal
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• v.31 no.2
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• pp.176-180
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• 2015

Postharvest diseases cause losses in a wide variety of crops around the world. Irradiation, a useful nonchemical approach, has been used as an alternative treatment for fungicide to control plant fungal pathogens. For a preliminary study, ionizing radiations (gamma, X-ray, or e-beam irradiation) were evaluated for their antifungal activity against Botrytis cinerea, Penicillium expansum, and Rhizopus stolonifer through mycelial growth, spore germination, and morphological analysis under various conditions. Different fungi exhibited different radiosensitivity. The inhibition of fungal growth showed in a dose-dependent manner. Three fungal pathogens have greater sensitivity to the e-beam treatment compared to gamma or X-ray irradiations. The inactivation of individual fungal-viability to different irradiations can be considered between 3-4 kGy for B. cinerea and 1-2 kGy for P. expansum and R. stolonifer based on the radiosensitive and radio-resistant species, respectively. These preliminary data will provide critical information to control postharvest diseases through radiation.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2650-2658
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• 2024

In this paper, we use a Monte Carlo (MC) simulation based on Geant4 to investigate the influence of four parameters on the spatial resolution of the lens-coupled lutetium yttrium orthosilicate (LYSO) scintillator, including the thickness of the LYSO scintillator, the F-number and minification factor of the lens, and the incident position of the gamma-rays. Simulation results show that when the gamma-rays are incident along the lens axis, the smaller the thickness, the larger the F-number, the larger the minification factor, the higher the spatial resolution, with an isotropic point spread function (PSF). As the incident position of the gamma-rays deviates from the lens axis, the spatial resolution decreases, and the PSF becomes anisotropic. In addition, by analyzing the whole physical process of the lens-coupled LYSO scintillator from gamma-rays to secondary electrons to fluorescence photons, we aim to provide a detailed analysis of the influence of each parameter on the spatial resolution. The results show that the PSF of the secondary electrons energy deposition is almost constant in the simulation, which determines the upper limit of the spatial resolution. Meanwhile, the dispersion process of the fluorescence photons can explain the reason why each parameter affects the spatial resolution.

• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.80-90
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• 1993

Radiation streaming through penetrations has been of great concern in radiation shielding design and analysis. This study developed a Monte Carlo method and constructed a data library of results calculated by the Monte Carlo method for radiation streaming through a straight cylindrical duct in concrete walls of a broad, mono-directional, mono-energetic gamma-ray beam of unit intensity. It was demonstrated that average dose rate due to an isotropic point source at arbitrary positions can be well approximated using the library with acceptable error. Thus, the library can be used for efficient analysis of radiation streaming due to arbitrary distributions of gamma-ray sources.