• Radiation Oncology Journal
• /
• v.3 no.2
• /
• pp.87-93
• /
• 1985

The interaction of radiation and 5-Fluorouracil (5-FU) on mouse jejunal crypt cells was studied using the microcolony survival assay. 150mg/kg of 5-FU was injected intraperitoneally 15 minutes before irradiation and 6 hours after irradiation. Jejunal crypt cells of mouse survived more when 5-FU was given 15 minutes before irradiation than giving it 6 hours after irradiation. The mean lethal doses (Do) of each of irradiation alone group, 5-FU injection group of 15 minutes preceding irradiation, and 5-FU injection group of 6 hours post irradiation were, 135, 135, and 114 rad respectively. The dose effect factor (DEF) of each of 5-FU injection groups of 15 minutes preceding irradiation and of 6 hours post irradiation were 1.13 and 1.27

• Macromolecular Research
• /
• v.15 no.1
• /
• pp.44-50
• /
• 2007

This study investigated the effect of ultrasound irradiation on the blend of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT). The blends of PLA/PBAT(50/50) (PBAT50) were prepared in a melt mixer with an ultrasonic device attached. Thermal, rheological, and mechanical properties, morphology, and biodegradability of the sonicated blends were analysed. The viscosity of the sonicated blends was increased by the ultrasound irradiation owing to the strong interaction. The morphology of the sonicated blends was significantly dependent on the duration o the ultrasound irradiation. For PBAT50, the phase size reduction was maximized when the blends were ultrasonically irradiated for 30 sec. At longer duration of ultrasound irradiation, the PBAT phase underwent flocculation. Measurement of the tensile properties showed an increased breakage tensile stress and an enhanced Young's modulus when the blends were properly irradiated. This improvement was ascribed to better adhesion between the PLA matrix and the PBAT domain and to better dispersion of the PBAT phase. However, the tensile properties were maximized after excessive energy irradiation, which was ascribed to an emulsifying effect leading to coalescence of the PBAT phase. Impact strength was increased to reach a peak with the ultrasound irradiation, and was higher than the untreated sample for all sonicated samples due to the difference of failure mechanism between the tensile test and the impact test.

• The Journal of Korean Physical Therapy
• /
• v.9 no.1
• /
• pp.71-79
• /
• 1997

The purpose of this study were to determined the effect of laser irradiation on the fibroblast activity. Cultures of 3T3 fibroblasts were subjected to Helium Neon laser(632.8 nm) irradiation of various energy density. On one, two and three consecutive days the fibroblast monolayers wert irradiated for period from 0 to 32 minutes with 8 mW of average output power. The fibroblast activity was determined by the quantitative assay of MTT, SRB and NR after incubation of the fibroblasts for 24 hours. Results show that exposure duration from 2 min to 32 min could increase MTT at three consecutive days, whereas control and 1 min, one and two days irradiation had were not inclosed. The SRB and NR were inclosed at two and three consecutive days from 2 min to 32 min, whereas control and 1 min, and once radiation were not increased. These result demonstrate that energy density from 0.48 to 7.64 J/cm could increase cellular protein contents and fibroblast activity at more than twice irradiation of laser, whereas low energy density (less than 0.24 J/m) and once irradiation of laser had no effect. The results suggest that the beneficial effect of the He-Ne laser with adequate dose on fibroblast activity in vitro.

• Journal of Radiation Industry
• /
• v.8 no.1
• /
• pp.7-10
• /
• 2014

This study was designed to evaluate the protective effect of silkworm hemolymph against ${\gamma}-irradiation$ induced damage in the liver of mice. Female Balb/C mice (6 weeks old) were exposed to ${\gamma}-irradiation$ (6 Gy) and administered orally to silkworm hemolymph ($5ml\;kg^{-1}$ BW) for 7 days post-irradiation. The body weight, spleen index, plasma aspartate transaminase (AST), plasma alanine transaminase (ALT), and liver malondialdehyde (MDA) levels were determined. Compared with irradiated control mice, the activity of plasma AST and the level of MDA were significantly decreased in mice treated silkworm hemolymph. These results show that silkworm hemolymph is found to have a protective effect against ${\gamma}-irradiation$ induced damage in mice.

• Journal of Radiation Protection and Research
• /
• v.42 no.1
• /
• pp.63-68
• /
• 2017

Background: The combined effect of the low energy electron (LEE) irradiation and $Cu^{2+}$ ion on DNA damage was investigated. Materials and Methods: Lyophilized pBR322 plasmid DNA films with various concentrations (1-15 mM) of $Cu^{2+}$ ion were independently irradiated by monochromatic LEEs with 5 eV. The types of DNA damage, single strand break (SSB) and double strand break (DSB), were separated and quantified by gel electrophoresis. Results and Discussion: Without electron irradiation, DNA damage was slightly increased with increasing Cu ion concentration via Fenton reaction. LEE-induced DNA damage, with no Cu ion, was only 6.6% via dissociative electron attachment (DEA) process. However, DNA damage was significantly increased through the combined effect of LEE-irradiation and Cu ion, except around 9 mM Cu ion. The possible pathways of DNA damage for each of these different cases were suggested. Conclusion: The combined effect of LEE-irradiation and Cu ion is likely to cause increasing dissociation after elevated transient negative ion state, resulting in the enhanced DNA damage. For the decrease of DNA damage at around 9-mM Cu ion, it is assumed to be related to the structural stabilization due to DNA inter- and intra-crosslinks via Cu ion.

• Journal of Magnetics
• /
• v.21 no.2
• /
• pp.159-163
• /
• 2016

Antiferromagnet (AFM)/ferromagnet (FM) bilayer structures are widely used in the magnetic devices of sensor and memory applications, as AFM materials can induce unidirectional anisotropy of the FM material via exchange coupling. The strength of the exchange coupling is known to be sensitive to quality of the interface of the AFM/FM bilayers. In this study, we utilize proton irradiation to modify the interface structures and investigate its effect on the magnetic properties of AFM/FM structures, including the exchange bias and magnetic thermoelectric effect. The magnetic properties of IrMn/CoFeB structures with various IrMn thicknesses are characterized after they are exposed to a proton beam of 3 MeV and $1{\sim}5{\times}10^{14}ions/cm^2$. We observe that the magnetic moment is gradually reduced as the amount of the dose is increased. On the other hand, the exchange bias field and thermoelectric voltage are not significantly affected by proton irradiation. This indicates that proton irradiation has more of an influence on the bulk property of the FM CoFeB layer and less of an effect on the IrMn/CoFeB interface.

• Nuclear Engineering and Technology
• /
• v.51 no.2
• /
• pp.501-509
• /
• 2019

In this paper a body-centered cubic(BCC) crystal plasticity model based on microscopic dislocation mechanism is introduced and numerically implemented. The model is coupled with irradiation effect via tracking dislocation loop evolution on each slip system. On the basis of the model, uniaxial tensile tests of unirradiated and irradiated RPV steel(take Chinese A508-3 as an example) at different temperatures are simulated, and the simulation results agree well with the experimental results. Furthermore, crystal plasticity damage is introduced into the model. Then the damage behavior before and after irradiation is studied using the model. The results indicate that the model is an effective tool to study the effect of irradiation and temperature on the mechanical properties and damage behavior.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
• /
• 1998.10a
• /
• pp.130-130
• /
• 1998

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
• /
• 1998.10a
• /
• pp.131-131
• /
• 1998

• Imaging Science in Dentistry
• /
• v.37 no.1
• /
• pp.35-43
• /
• 2007

Purpose : To observe direct effect of irradiation on cariogenic Streptooccus mutans. Materials and Methods : S. mutans GS5 was exposed to irradiation with a single absorbed dose of 10, 20, 30, and 40Gy. Viability and changes in antibiotic sensitivity, morphology, transcription of virulence factors, and protein profile of bacterium after irradiation were examined by pour plate, disc diffusion method, transmission electron microscopy, RT-PCR, and SDS-PAGE, respectively. Results : After irradiation with 10 and 20Gy, viability of S. mutans was reduced. Further increase in irradiation dose, however, did not affect the viability of the remaining cells of S. mutans. Irradiated 5. mutans was found to have become sensitive to antibiotics. In particular, the bacterium irradiated with 40Gy increased its susceptibility to cefotaxime, penicillin, and tetracycline. Under the transmission electron microscope, number of morphologically abnormal cells was increased as the irradiation dose was increased. S. mutans irradiated with 10 Gy revealed a change in the cell wall and cell membrane. As irradiation dose was increased, a higher number of cells showed thickened cell wall and cell membrane and Iysis, and appearance of ghost cells was noticeable. In RT-PCR, no difference was detected in expression of gtfB and spap between cells with and without irradiation of 40Gy. In SDS-PAGE, proteins with higher molecular masses were gradually diminished as irradiation dose was increased. Conclusion : These results suggest that irradiation affects the cell Integrity of S. mutans, as observed by SDS-PAGE, and as manifested by the change in cell morphology, antibiotic sensitivity, and eventually viability of the bacterium.