• Journal of Radiation Protection and Research
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• v.31 no.2
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• pp.65-68
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• 2006

In this study, the extent of plasmid DNA damage was observed according to concentration of BSH(Boron Sulfhydryl Hydride) and irradiation doses of neutron and ${\gamma}$-ray. The plasmid used was both pBR 322 (2870 bp) and ${\Phi}X174$ RF(5386 bp) DNA. Plasmid DNA damage by irradiation in the presence of BSH was analyzed by agarose gel electrophoresis. In the neutron experiment, DNA damage of both plasmid DNAs was increased according to increasing the concentration of BSH and neutron doses. But in the ${\gamma}$-ray experiment, there appeared no dose dependency as compared to the neutron experiment. The extent of the plasmid DNA damage in the presence of BSH was somewhat different according to irradiation by neutron or ${\gamma}$-ray.

• Journal of Radiation Protection and Research
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• v.33 no.2
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• pp.53-59
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• 2008

We observed DNA damages as a function of mean absorbed dose to identify the indirect effect of high-energy radiation such as x-ray. Monolayer films of lyophilized pGEM-3Zf(-) plasmid DNA deposited on tantalum foils were exposed to Al $K{\alpha}$ X-ray (1.5 keV) for 0, 3, 7 and 10 min, respectively, in a condition of ultrahigh vacuum state. We compared DNA damages by X-ray irradiation with those by 3 eV electron irradiation. X-ray photons produced low-energy electrons (mainly below 20 eV) from the tantalum foils and DNA damage was induced chiefly by these electrons. For electron beam irradiation, DNA damage was directly caused by 3 eV electrons. Irradiated DNA was analyzed by agarose gel electrophoresis and quantified by ImagaQuant program. The quantities of remained supercoiled DNA after irradiation were linearly decreased as a function of mean absorbed dose. On the other hand, the yields of nicked circular (single strand break, SSB) and interduplex crosslinked form 1 DNA were linearly increased as a function of mean absorbed dose. From this study, it was confirmed that DNA damage was also induced by low energy electrons ($0{\sim}10\;eV$) even below threshold energies for the ionization of DNA.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.301-307
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• 2013

In the present study, space doses generated during X-ray radiography of hand, head, and abdomen, etc. were examined and whether the intensity of space doses of scattering rays is attenuated by the "inverse square law of distance" was figured out. First, the space doses of X-ray with small amounts of generated scattering rays such as hand radiography were mostly attenuated by the "inverse square law of distance" and were not detected at all at a distance of 2m. Second, the space doses of X-ray with large amounts of generated scattering rays such as head or abdomen radiography attenuated in higher rates than the rates under the "inverse square law of distance" at distances ranging from 30cm to 1m from the center of the irradiation field and were attenuated by the "inverse square law of distance" at distances ranging from 1m to 2m. Therefore, in X-ray rooms, the subject should be at least 2m away from the center of the irradiation field in the case of hand radiography and X-ray exposure prevention actions using protective devices are required in the entire spaces of the X-ray rooms in the case of head or abdomen radiography.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.53-56
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• 2009

At room-temperature, a facile, seedless, and environmentally benign green route for the synthesis of star like PbS nanoclusters at 7 min in aqueous solution of 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM] [$EtSO_{4}$], room-temperature ionic liquid (RTIL), via ultrasonic irradiation is proposed. The X-ray diffraction studies display that the products are excellently crystallized in the form of cubic structure. An energy dispersive X-ray spectroscopy (EDX) investigation reveals the products are extremely pure. The absorption spectra of the product exhibit band gap energy of about 4.27 eV which shows an enormous blue shift of 3.86 eV that can be attributed to very small size of PbS nanoparticles produced and quantum confinement effect. A possible formation mechanism of the PbS nanoparticles using ultrasonic irradiation in aqueous solution of the RTIL is presented.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.832-835
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• 2007

Moisture content of normal, waxy, and high amylose com starches was adjusted to 10-35%, and irradiated in a microwave oven. The effect of microwave irradiation on the crystalline structure of starch was measured by using a differential scanning calorimetry (DSC), and X-ray diffractometry. Pasting viscosity profile was also determined by using a rapid viscoanalyzer (RVA). For all the 3 types of starches tested, the rate of temperature increase by the microwave irradiation was faster and more rapidly reached the maximum temperature of the pressure bomb ($120^{\circ}C$) when the moisture content was higher. X-ray diffraction and DSC data revealed that the microwave irradiated starch underwent partial disruption of crystalline structure. RVA studies showed that the irradiation caused significant reductions in maximal viscosity and breakdown, whereas pasting temperature was increased. Overall trends revealed that the microwave irradiation on the starch containing limited moisture content (less than 35%) provided the effects similar to the heat moisture treatment. These effects became more significant when the moisture content was higher. Compared to waxy com starch, normal, and high amylose com starches appeared to be more susceptible to the microwave irradiation.

• KSBB Journal
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• v.15 no.1
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• pp.84-87
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• 2000

We studied the effect of ultrasoft X-ray obtained from the Pohang Light Source (PLS), on the mutation of E. coli and the damage of plasmid. After irradiation, the supercoiled plasmid DNA converted to the relaxed-form, and then to the linear-form. We transformed the irradiated plasmid DNA and isolated $\beta$-galactosidase mutants. We also isolated $\beta$-galactosidase mutants from the directly irradiated cells. There were preferred mutational sites on DNA induced by ultrasoft X-ray.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.6 no.1
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• pp.45-50
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• 1976

The author observed morphological change in palate development of rat embryo after irradiation of x-ray on the one side of the duplex uterus. The time-matings occured between 6 p.m. and 8 p.m. and all females with copulation plugs at 8 a.m. were isolated and properly marked for evidence of copulation. The lower left abdomen of mothers were exposed to x-radiation on the 7 1/2th, 9 1/2th, 11 1/2th day of gestation, respectively 150, 250, 350, 500rads. At 18 1/2th day of post-conception, the pregnant females were dissected and the contents of the two uteri examined. The translucent sample by Alizarin red S stain were prepared. The results were as follows; 1. The result that groups irradiated by 250rads and 350rads made marked difference in comparison with the control group suggests the x-ray to be a inducing factor of cleft palate. 2. At 11 1/2th day of gestation, incidence of cleft palate induced by x-irradiation was highest. 3. Mortality showed the highest frequency at 7 1/2th day of gestation and tended to decrease in according to increasing of age. 4. Morphology of cleft palate induced by x-irradiation showed similarity in comparison with those induced by other factors having reported ever.

• Biomedical Science Letters
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• v.12 no.1
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• pp.43-48
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• 2006

Present study aimed to investigate recovering effect of propolis on blood components and tissues of mouse after low dose irradiation. It is verified that the contents of Fe, Mg, P, Zn and Cu in propolis dosed blood are increased slightly than irradiated blood, however, the contents of Ba and Pb are decreased to one tenth than irradiated blood and the contents of Fe and P are increased to 10% than control group. We consider this result as the propolis acts a role of defence factor minimizing changes of elements caused by irradiation in blood. Among the blood components, Glutamate oxaloacetate transaminase (GOT) value is increased after the radiation but after dosed with propolis and irradiated the value is decreased, suggesting that propolis as a buffering material against irradiation. After dosed with propolis, a number of spermatogenic cells are lowered in testis tissue, however, nucleus and cytoplasm are clearly observed in spermatogonia, spermatocytes and spermatid cells. And nucleus and membrane of cells in the proximal convoluted tubule of renal tissue are clearly observed. Also, cytoplasmand membrane of surface mucous cells in stomach tissue are appeared in normal which is almost like those of control group. We consider that the propolis used in this study is preventing deformations of cells increasing resistance capacity against irradiation rather than recovering damaged tissues.

• BMB Reports
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• v.45 no.10
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• pp.571-576
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• 2012

Radiotherapy is considered to cause detrimental effects on bone tissue eventually increasing bone loss and fracture risk. However, there is a great controversy on the real effects of irradiation itself on osteoblasts, and the mechanisms by which irradiation affects osteoblast differentiation and mineralization are not completely understood. We explored how X-ray radiation influences differentiation and bone-specific gene expression in mouse calvarial osteoblasts. Irradiation at 2 Gy not only increased differentiation and mineralization of the cells, but also upregulated the expression of alkaline phosphatase, type I collagen, osteopontin, and osteocalcin at early stages of differentiation. However, irradiation at higher doses (>2 Gy) did not stimulate osteoblast differentiation, rather it suppressed DNA synthesis by the cells without a toxic effect. Additional experiments suggested that transforming growth factor-beta 1 and runt-transcription factor 2 play important roles in irradiation- stimulated bone differentiation by acting as upstream regulators of bone-specific markers.

• Progress in Superconductivity and Cryogenics
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• v.24 no.1
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• pp.18-22
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• 2022

The effect of electron beam (EB) irradiation on superconducting properties and microstructures of MgB₂ bulk superconductors were investigated. At E-beam doses of 1×10¹⁶ e/cm² and 1×10¹⁷ e/cm², the effect of irradiation on a superconducting transition temperature (T_c) of MgB₂ was weak. As a dose increases to 5×10¹⁷ e/cm², T_c decreases by 0.5 K. The critical current density (J_c) measured at 4.2 K and 20 K, and 0 T - 5 T increases slightly as exposure time increases. X-ray diffraction for the irradiation surface of MgB₂ shows that the diffraction intensity of (hkl) peaks decreases proportionally as the exposure time increases. This indicates that the crystallinity of MgB₂ was degraded by irradiation. TEM investigation for the irradiated sample showed distorted lattice structure, which is consistent with the XRD results. The J_c increase and T_c reduction of MgB₂ by irradiation are believed to be caused by the lattice distortion.