• Title/Summary/Keyword: Radiation sensitivity

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Radiation Sensitivity of Some Food Decay Fungi (몇몇 음식 부식 균류의 방사선 감수성에 대한 연구)

  • 장학길;이배함
    • Korean Journal of Microbiology
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    • v.18 no.1
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    • pp.1-6
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    • 1980
  • Five species of food decay fungl, Aspergillus flavus, Asp. uiger, Penicillum sp., Botrytis cinerea, and Rhizopus stolonifer, were examined for their radio sensitivity in several suspension media. Asp. flavus, Asp. niger and Penicillum sp. have almost the same sensitivity toward gamma rays. with D value in the range of 30 to 35 K rad, whereas Botrytis cinerea has a D value of approximately 55K rad and Rhizopus stolonifer, the most re4sistant fungus studied, has a crease in their radioresistnace when compared with spores irradiated in water. Asp. flavus and penicillium sp. spores irradiated in citrate buffer at pH3-7 showed almost no change in their radisensitiity with pH, but Botryis cinerea spores showed a distinct decrease in their radioresistnace at pH 6 and 7. Penicillum sp. spores irradiated in sucrose solutions showed no sinificant change in their radioresistance. Botrytis cinerea spores displayed a higher radioresistance when they were irradiated in sucrose solution than in water.

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Fabrication of a SOI hall sensor using Si-wafer direct bonding technology and its characteristics (실리콘기판 직접접합기술을 이용한 SOI 홀 센서의 제작과 그 특성)

  • 정귀상
    • Electrical & Electronic Materials
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    • v.8 no.2
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    • pp.165-170
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    • 1995
  • This paper describes the fabrication and characteristics of a Si Hall sensor fabricated on a SOI (Si-on-insulator) structure. The SOI structure was formed by SDB(Si-wafer direct bonding) technology and the insulator of the SOI structure was used as the dielectrical isolation layer of a Hall sensor. The Hall voltage and sensitivity of the implemented SDB SOI Hall sensors showed good linearity with respect to the applied magnetic flux density and supplied current. The product sensitivity of the SDB SOI Hall sensor was average 600V/A.T and its value has been increased up to 3 times compared to that of bulk Si with buried layer of 10.mu.m. Moreover, this sensor can be used at high-temperature, high-radiation and in corrosive environments.

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Sensitivity of GAGG based scintillation neutron detector with SiPM readout

  • Fedorov, A.;Gurinovich, V.;Guzov, V.;Dosovitskiy, G.;Korzhik, M.;Kozhemyakin, V.;Lopatik, A.;Kozlov, D.;Mechinsky, V.;Retivov, V.
    • Nuclear Engineering and Technology
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    • v.52 no.10
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    • pp.2306-2312
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    • 2020
  • Here we report on the first results of sensitivity evaluation of the gadolinium-aluminum-gallium- garnet (GAGG) scintillation detector with SiPM readout to fast and slow neutrons and, to the natural background and Co-60 γ-radiation as well. Data on sensitivity were obtained using certified dosimetry benches, so it can be utilized in the calculation of detection limits of neutron flux with such type of detectors. It was concluded that use of GAGG scintillator has a good prospect for neutron monitoring in different parts of nuclear research reactors and power plants.

Induction of Micronuclei in Human and Mouse Lymphocytes Irradiated with Gamma Radiation and Effect of Panax ginseng C.A. Meyer (마우스와 사람 림프구에서 방사선에 의한 미소핵의 형성 및 고려인삼의 효과)

  • Kim, Sung-Ho;Oh, Heon;Lee, Song-Eun;Lee, Yun-Sil;Kim, Tae-Hwan;Jeong, Kyu-Sik;Ryu, Si-Yun
    • Journal of Radiation Protection and Research
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    • v.22 no.3
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    • pp.153-160
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    • 1997
  • The frequencies of ${\gamma}$-ray-induced micronuclei (MN) in cytokinesis-blocked (CB) lymphocytes at several doses were measured in three donors of human and C57BL/6 mice. Measurements performed after irradiation showed a dose-related increases in MN frequency in each of the donors studied. The relative sensitivity of mouse in spleen lymphocytes (SLs) compared with human peripheral blood lymphocytes (PBLs) was estimated by best fitting linear-quadratic model based on the radiation-induced MN data over the range from 0 cGy to 400 cGy. In the case of MN frequency with 0.2 per CB cell, the relative sensitivity of mouse SLs was 1.67. Compared with the radiation-induced MN formation in the PBLs of human, the SLs of mouse were more radiosensitive. Using this MN assay with human PBLs and mouse SLs, studies were performed to determine whether the water fraction of ginseng (Panax ginseng C.A.Meyer) against radiation-induced MN in human PBLs after in vitro irradiation (3Gy) and in SLs of C57BL/6 mice after in vivo irradiation (3Gy). The frequency of MN in human PBLs was reduced by water fraction of ginseng (0.5mg/ml of medium) both pre-and post treatment (p<0.0l) in vitro. In addition, the frequency of MN in mouse SLs was also reduced by pretreatment of ginseng (2mg/ml of drinking water for 7days) in vivo. The data suggested that the ginseng may reduce cell damage caused by ${\gamma}$-rays in vitro and in vivo. Further studies are needed to characterize better the protective nature of ginseng extract, its fractions and compounds.

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The Expression of Hypoxia Inducible Factor-1 $\alpha$ by Desferrioxamine Induces Radioresistance in Mouse Hepatoma Cell Line (쥐의 간암 세포에서 Desferrioxamine에 의해 유도된 Hypoxia Inducible Factor-1 $\alpha$가 방사선 저항성을 초래함)

  • Kwon, Byung-Hyun
    • Radiation Oncology Journal
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    • v.22 no.3
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    • pp.217-224
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    • 2004
  • Purpose: It is well known that the radiosensitivity of tumor cells can be significantly reduced under hypoxic conditions. Hypoxia-inducible factor-1 $\alpha$ (HIF-1 $\alpha$) plays a pivotal role in the essential adaptive responses to hypoxia. Therefore this study investigated the relationship between HIF-1 $\alpha$ expression and radiosensitivity. M Mouse hepatoma cell line hepafcic7 and HIF-1 $\beta$-deficient mutant cell line hepa1C4 were used to analyze the role of HIF-1 a. on radiosensitivity. These cells were exposed for 6 h to desferrioxamine (DFX) before radiation. HIF-1$\alpha$. expression was examined by Western blot. Apoptosis was assessed by DNA fragmentation, propidium iodide staining, and apoptotic cell death detection ELISA kit. Radiation sensitivity was determined using MTT assay. The radiobioiogical parameters, surviving fractions at 2 Gy and 8 Gy, and mean inactivation dose (MID) from the linear-quadratic model were used to assess radiation sensitivity in the statistical analyses. Results: The expression of HIF-1 $\alpha$. was Increased, whereas apoptosis was decreased, by radiation In the presence of DFX In hepal cl c7, but not In hepal C4. The radlosensitivity of hepal C4 cells was not significantly affected by DFX treatment. The radiosensitivlty of hepal cl c7 cells was significantly decreased in the presence of DFX Conclusion: The expression of HIF-1 w by hypoxia-mimic agent DFX reduced apoptosls and radiosensitlvity in mouse hepatoma cell line hepafclc7. These results suggested that HIF-1 u could be Induced by irradiation in hypoxic ceils of tumor masses, and that this mlght Increase radioresistance in hypoxic cells.

Evaluation of DNA Damage and Repair Kinetics in the Earthworm (Eisenia fetida) Exposed to Radiation and Mercury (방사선과 수은에 의해 유도된 Eisenia fetida 체강세포의 DNA 손상 및 수복 평가)

  • Ryu, Tae-Ho;Nili, Mohammad;An, Kwang-Guk;Kim, Jin-Kyu
    • Korean Journal of Environmental Biology
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    • v.29 no.1
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    • pp.68-73
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    • 2011
  • The single cell gel electrophoresis (SCGE) assay is a microelectrophoretic technique for assessments of DNA damage at the level of the individual eukaryotic cell. The SCGE assay, due to its simplicity, sensitivity and need of a few cells, has advantages compared to other genomic damage assays such as sister chromatid exchange, chromosomal aberration and micronucleus test. In this study, investigated were the levels of DNA damage and the repair kinetics in the coelomocytes of Eisenia fetida treated with HgCl2 and ionizing radiation by means of the SCGE assay. For detecting DNA damage and repair in coelomocytes, earthworms (E. fetida) were irradiated with six doses of ${\gamma}$-rays (0, 2.5, 5, 10, 20 and 50 Gy) and in vivo exposed to mercuric chloride at 0, 80 and 160 mg $kg^{-1}$ for 48 hours. Then the Olive tail moments were measured during 0~12 hours after irradiation and 0~72 hours after Hg treatment. The results showed that the more the oxidative stress was induced by mercury and radiation, the longer the repair time was required. Also, the results suggest that the SCGE assay may be used as an important tool for comparison of the sensitivity of different species to oxidative stresses.

Radiation Activity of Safety-Related Fission Products of DUPIC Fuel

  • Ryu, Ho-Jin;Park, Chang-Je;Park, Hangbok;Song, Kee-Chan
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2004.06a
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    • pp.397-398
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    • 2004
  • It is important to estimate the radiation activity of the nuclear fuel which is a source term of the loss of coolant accident. The purpose of this study is to identify the most important parameters of the source term calculation based on three fuel types: typical natural uranium CANDU fuel, slightly enriched uranium and DUPIC fuel. The characteristics of the radiation source term were analyzed through sensitivity calculations of the linear power, fuel turnup, and the power shape.(omitted)

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A Study on the Development of Nuclear Radiation Detector with Silicon PIN Photodiode (실리콘 포토다이오드를 이용한 방사선 검출기 개발에 관한 연구)

  • Yi, Un-K.;Kim, Jung-S.;Sohn, Chang-H.;Baek, Kwang-R.
    • Proceedings of the KIEE Conference
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    • 1999.11c
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    • pp.754-756
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    • 1999
  • In this paper, we have developed a high-sensitivity SNRD(Semiconductor Nuclear Radiation Detector) using silicon PIN photodiode. The SNRD is constructed with silicon PIN photodiode(S3590-05), preamplifier and shaping amplifier. To show the effectiveness of SNRD, nuclear radiation experiments are conducted with $\gamma$-ray Ba-133, Cs-137 and Co-60. The SNRD is different in characteristics of the energy spectrum to scintillation detectors. However, the SNRD have a good linearity on $\gamma$-ray energy and activity. The results of this paper can be applied to electronic personal dosimeter.

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