• Journal of Periodontal and Implant Science
• /
• v.53 no.2
• /
• pp.110-119
• /
• 2023

Purpose: This study aimed to investigate the proper wavelengths for safe levels of light-emitting diode (LED) irradiation with bactericidal and photobiomodulation effects in vitro. Methods: Cell viability tests of fibroblasts and osteoblasts after LED irradiation at 470, 525, 590, 630, and 850 nm were performed using the thiazolyl blue tetrazolium bromide assay. The bactericidal effect of 470-nm LED irradiation was analyzed with Streptococcus gordonii, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, and Tannerella forsythia. Levels of nitric oxide, a proinflammatory mediator, were measured to identify the anti-inflammatory effect of LED irradiation on lipopolysaccharide-stimulated inflammation in RAW 264.7 macrophages. Results: LED irradiation at wavelengths of 470, 525, 590, 630, and 850 nm showed no cytotoxic effect on fibroblasts and osteoblasts. LED irradiation at 630 and 850 nm led to fibroblast proliferation compared to no LED irradiation. LED irradiation at 470 nm resulted in bactericidal effects on S. gordonii, A. actinomycetemcomitans, F. nucleatum, P. gingivalis, and T. forsythia. Lipopolysaccharide (LPS)-induced RAW 264.7 inflammation was reduced by irradiation with 525-nm LED before LPS treatment and irradiation with 630-nm LED after LPS treatment; however, the effects were limited. Conclusions: LED irradiation at 470 nm showed bactericidal effects, while LED irradiation at 525 and 630 nm showed preventive and treatment effects on LPS-induced RAW 264.7 inflammation. The application of LED irradiation has potential as an adjuvant in periodontal therapy, although further investigations should be performed in vivo.

• Nuclear Engineering and Technology
• /
• v.45 no.3
• /
• pp.311-322
• /
• 2013

High-Cr martensitic steel HT-9 is one of the candidate materials for advanced nuclear energy systems. Thanks to its excellent thermal conductivity and irradiation resistance, ferritic/martensitic steels such as HT-9 are considered for in-core applications of advanced nuclear reactors. The harsh neutron irradiation environments at the reactor core region pose a unique challenge for structural and cladding materials. Microstructural and microchemical changes resulting from displacement damage are anticipated for structural materials after prolonged neutron exposure. Consequently, various irradiation effects on the service performance of in-core materials need to be understood. In this work, the fundamentals of radiation damage and irradiation effects of the HT-9 martensitic steel are reviewed. The objective of this paper is to provide a background introduction of displacement damage, microstructural evolution, and subsequent effects on mechanical properties of the HT-9 martensitic steel under neutron irradiations. Mechanical test results of the irradiated HT-9 steel obtained from previous fast reactor and fusion programs are summarized along with the information of irradiated microstructure. This review can serve as a starting point for additional investigations on the in-core applications of ferritic/martensitic steels in advanced nuclear reactors.

• Nuclear Engineering and Technology
• /
• v.55 no.2
• /
• pp.408-420
• /
• 2023

Beryllium oxide (BeO) is being re-emphasized and utilized in Micro Modular Reactors (MMR) because of its prominent nuclear and high temperature properties in recent years. The implications of the research about effects of neutron irradiation on the microstructure and properties of BeO are significant. This article comprehensively reviews the effects of neutron irradiation on BeO and proposes the maximum permissible neutron doses at different temperatures for BeO without cracks in appearance according to the data in the previous literature. This maximum permissible neutron dose value has important reference significance for the experimental study of BeO. The effects of neutron irradiation on the thermal conductivity and flexural strength of BeO are also discussed. In addition, microstructure evolution of irradiated BeO during post-irradiation annealing is summarized. This review article has important implications for the application of BeO in MMR.

• Toxicological Research
• /
• v.26 no.2
• /
• pp.109-115
• /
• 2010

The purpose of this study was to elucidate the mechanism underlying enhanced radiosensitivity to $^{60}Co\;{\gamma}$-irradiation in human prostate PC-3 cells pretreated with berberine. The cytotoxic effect of the combination of berberine and irradiation was superior to that of berberine or irradiation alone. Cell death and Apoptosis increased significantly with the combination of berberine and irradiation. Additionally, ROS generation was elevated by berberine with or without irradiation. The antioxidant NAC inhibited berberine and radiation-induced cell death. Bax, caspase-3, p53, p38, and JNK activation increased, but activation of Bcl-2, ERK, and HO-1 decreased with berberine treatment with or without irradiation. Berberine inhibited the anti-apoptotic signal pathway involving the activation of the HO-1/NF-${\kappa}B$-mediated survival pathway, which prevents radiation-induced cell death. Our data demonstrate that berberine inhibited the radioresistant effects and enhanced the radiosensitivity effects in human prostate cancer cells via the MAPK/caspase-3 and ROS pathways.

• Nuclear Engineering and Technology
• /
• v.54 no.7
• /
• pp.2359-2366
• /
• 2022

Selecting graphite grades with superior irradiation characteristics is important task for designers of graphite moderation reactors. To provide reference information and data for graphite selection, the effects of irradiation on three fine-grained, iso-molded nuclear grade graphites, ETU-10, IG-110, and NBG-25, were compared based on irradiation-induced changes in volume, thermal conductivity, dynamic Young's modulus, and coefficient of thermal expansion. Data employed in this study were obtained from reported irradiation test results in the high flux isotope reactor (HFIR)(ORNL) (ETU-10, IG-110) and high flux reactor (HFR)(NRL) (IG-110, NBG-25). Comparisons were made based on the irradiation dose and irradiation temperature. Overall, the three grades showed similar irradiation-induced property change behaviors, which followed the historic data. More or less grade-sensitive behaviors were observed for the changes in volume and thermal conductivity, and, in contrast, grade-insensitive behaviors were observed for dynamic Young's modulus and coefficient of thermal expansion changes. The ETU-10 of the smallest grain size appeared to show a relatively smaller VC to IG-110 and NBG-25. Drastic decrease in the difference in thermal conductivity was observed for ETU-10 and IG-110 after irradiation. The similar irradiation-induced properties changing behaviors observed in this study especially in the DYM and CTE may be attributed to the assumed similar microstructures that evolved from the similar size coke particles and the same forming method.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.4
• /
• pp.334-338
• /
• 2003

The objective of this study was to demonstrate whether or not the deleterious effects of accelerated aging on seed vigour and viability are alleviated by interaction with gamma irradiation. Seeds of soybean (Glycine max L.) were artificially aged and subsequently irradiated with 4 and 8 Gy of gamma irradiation. Germination rate was negatively affected by accelerated aging and positively by gamma irradiation, with a positive interaction of a 3day-seed aging treatment occurring with 4 Gy, possibly suggesting that 4 Gy of gamma irradiation partially offset the adverse effects of seed aging on germination. However, 5-day aged seeds did not gain any benefits from the gamma irradiation. Electrolyte leakage from the seeds increased with the duration in days aged. Irradiation, however, did not impose any effects on the leakage. Respiration rate of the seed with hypocotyl and primary root was significantly low for the aged seeds, but not for the seeds with both irradiation and aging treatments. Accelerated aging decreased the dry weight of the hypocotyl and primary root of the seeds without any measurable effects of irradiation. $\alpha$-Amylase activity decreased with seed aging and positively responded to gamma irradiation. The data is discussed with regard to the possible roles of gamma irradiation for improving the seed vigour and viability of aged seeds.

• Food Science of Animal Resources
• /
• v.44 no.4
• /
• pp.779-789
• /
• 2024

The effects of irradiation on meat constituents including water, proteins, and lipids are multifaceted. Irradiation leads to the decomposition of water molecules, resulting in the formation of free radicals that can have both positive and negative effects on meat quality and storage. Although irradiation reduces the number of microorganisms and extends the shelf life of meat by damaging microbial DNA and cell membranes, it can also accelerate the oxidation of lipids and proteins, particularly sulfur-containing amino acids and unsaturated fatty acids. With regard to proteins, irradiation affects both myofibrillar and sarcoplasmic proteins. Myofibrillar proteins, such as actin and myosin, can undergo depolymerization and fragmentation, thereby altering protein solubility and structure. Sarcoplasmic proteins, including myoglobin, undergo structural changes that can alter meat color. Collagen, which is crucial for meat toughness, can undergo an increase in solubility owing to irradiation-induced degradation. The lipid content and composition are also influenced by irradiation, with unsaturated fatty acids being particularly vulnerable to oxidation. This process can lead to changes in the lipid quality and the production of off-odors. However, the effects of irradiation on lipid oxidation may vary depending on factors such as irradiation dose and packaging method. In summary, while irradiation can have beneficial effects, such as microbial reduction and shelf-life extension, it can also lead to changes in meat properties that need to be carefully managed to maintain quality and consumer acceptability.

• Environmental Engineering Research
• /
• v.22 no.4
• /
• pp.426-431
• /
• 2017

Some phototoxicity of titanium dioxide nanoparticles ($TiO_2$ NPs) has been reported in recent years in studies with fish embryos or larvae. However, it is necessary to focus on the potential effects of embryonic exposure due to irreversible abnormalities and mortalities observed in sac-fry, and to expand various fish embryos to generate multiple test species. The aim of this study was to evaluate the effects of $TiO_2$ NPs under different irradiation conditions in exposed Oryzias latipes (O. latipes) at the embryonic and sac-fry stages. The effects of different irradiation conditions were observed using ultra-violet (UV) and visible light, and the corresponding effects were monitored by determining cumulative mortality and abnormality. O. latipes were exposed for 8 d to 0, 1, 5, 10, or 50 mg/L $TiO_2$ NPs under UV ($4,818.86mW/m^2$ at the bottom of clear vials) or visible light, after which the embryos were transferred to NP-free embryo-rearing solution until 16 days post fertilization (dpf). Abnormalities of embryos and sac-fry increased at high $TiO_2$ NP concentrations under UV irradiation, compared to control samples treated with visible light or UV irradiation alone. This work provides information regarding the phototoxicity of $TiO_2$ NPs using O. latipes at the embryonic and sac-fry stages.

• New & Renewable Energy
• /
• v.2 no.1 s.5
• /
• pp.56-65
• /
• 2006

The thermal performance of glass evacuated tube solar collectors are numerically and experimentally investigated. Four different shapes of solar collectors are considered and the performances of these solar collectors are compared. Dealing with a single collector tube, the effects of not only the shapes of the absorber tube but also the incidence angle of solar irradiation (beam irradiation) on thermal performance of the collector are studied. However, the solar irradiation consists of the beam irradiation as well as the diffuse irradiation. Also, the interference of solar irradiation and heat transfer interaction between the tubes exist in an actual solar collector, These effects are considered in this study experimentally and numerically. The accuracy of the numerical model is verified by the experimental results. The result shows that the thermal performance of the absorber used a plate fin and U-tube is the best.

• YAKHAK HOEJI
• /
• v.44 no.1
• /
• pp.9-15
• /
• 2000

Four 3-alkoxy-6-allylthiopyridazines and 3-chloro-6-allylthiopyridazine were synthesized and their protective effects against oxidative stress and UV-C irradiation were tested. 3-Methoxy-6-allylthiopyridazine and 3-ethoxy-6-allylthiopyridazine did not show protective effect on the oxidative stress but showed the strongest protective effect on UV-C irradiation among the tested compounds. Especially 500 $\mu\textrm{g}$/$m\ell$ of the two compounds was the most effective concentration.