Effect of gamma irradiation on Korean traditional multicolored paintwork

Yoon, Minchul,Kim, Dae-Woon,Choi, Jong-il,Chung, Yong-Jae,Kang, Dai-Ill,Hoon Kim, Gwang,Son, Kwang-Tae,Park, Hae-Jun,Lee, Ju-Woon Elsevier 2015 Radiation physics and chemistry Vol.115 No.-

<P><B>Abstract</B></P> <P>Gamma irradiation can destroy fungi and insects involved in the bio-deterioration of organic cultural heritages. However, this irradiation procedure can alter optical and structural properties of historical pigments used in wooden cultural heritage paintings. The crystal structure and color centers of these paintings must be maintained after application of the irradiation procedure. In this study, we investigated the effects of gamma irradiation on Korean traditional multicolored paintwork (Dancheong) for the preservation of wooden cultural heritages. The main pigments in Korean traditional wooden cultural heritages, <I>Sukganju</I> (Hematite; Fe<SUB>2</SUB>O<SUB>3</SUB>), <I>Jangdan</I> (Minium; Pb<SUB>3</SUB>O<SUB>4</SUB>), <I>Whangyun</I> (Crocoite; PbCrO<SUB>4</SUB>), and <I>Jidang</I> (Rutile; TiO<SUB>2</SUB>), were irradiated by gamma radiation at doses of 1, 5, and 20kGy. After irradiation, changes in Commision Internationale d’Eclairage (CIE) color values (<I>L</I>*, <I>a</I>*, <I>b</I>*) were measured using the color difference meter, and their structural changes were analyzed using X-ray diffraction (XRD) analysis. The slightly change in less than 1 <I>dE</I>* unit by gamma irradiation was observed, and structural changes in the Dancheong were stable after exposure to 20kGy gamma irradiation. In addition, gamma irradiation could be applied to painted wooden cultural properties from the Korean Temple. Based on the color values, gamma irradiation of 20kGy did not affect the Dancheong and stability was maintained for five months. In addition, the fungicidal and insecticidal effect by less than 5kGy gamma irradiation was conformed. Therefore, the optical and structural properties of Dancheong were maintained after gamma irradiation, which suggested that gamma irradiation can be used for the preservation of wooden cultural heritages painted with Dancheong.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effects of gamma irradiation on the Dancheong were evaluated. </LI> <LI> We confirmed that optical and structural properties of Dancheong were maintained. </LI> <LI> Irradiation can contribute the decontamination for wooden cultural heritages. </LI> <LI> It also can be used for preservation of painted-wooden cultural heritages. </LI> </UL> </P>

Hyperfractionated radiotherapy for re-irradiation of recurrent esophageal cancer

Kazuya Takeda,Haruo Matsushita,Rei Umezawa,Takaya Yamamoto,Yojiro Ishikawa,Noriyoshi Takahashi,Yu Suzuki,Keiichi Jingu 대한방사선종양학회 2021 Radiation Oncology Journal Vol.39 No.4

Purpose: Re-irradiation is a treatment option for recurrent esophageal cancer patients with a history of radiotherapy, but there is a risk of severe late adverse effects. This study focused on the efficacy and safety of re-irradiation using hyperfractionated radiotherapy. Materials and Methods: Twenty-six patients who underwent re-irradiation by the hyperfraction technique using twice-daily irradiation of 1.2 Gy per fraction for recurrent esophageal cancer were retrospectively included in this study. The overall survival period after the start of secondary radiotherapy and the occurrence of late adverse effects were investigated. Results: Of 26 patients, 21 (81%) received re-irradiation with definitive intention and 21 (81%) underwent concurrent chemotherapy. The median re-irradiation dose was 60 Gy in 50 fractions in 25 treatment days, and the median accumulated irradiation dose in equivalent dose in 2 Gy per fraction was 85.4 Gy with an α/β value of 3. The median interval between two courses of radiotherapy was 21.0 months. The median overall survival period was 15.8 months and the 1-year and 3-year overall survival rates were 64.3% and 28.3%, respectively. Higher dose of re-irradiation and concurrent chemotherapy significantly improved survival (p < 0.001 and p = 0.019, respectively). Severe late adverse effects with the Common Terminology Criteria for Adverse Events grade 3 or higher were observed in 5 (19.2%) patients, and 2 (7.7%) of them developed a grade 5 late adverse effect. Conclusion: High-dose re-irradiation using a hyperfractionated schedule with concurrent chemotherapy might be related to good prognosis, while the rate of late severe adverse effects is not high compared with the rates in past reports.

Irradiation Effects of HT-9 Martensitic Steel

Yiren Chen 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.3

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-9martensitic 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.

Coupled irradiation-thermal-mechanical analysis of the solid-state core in a heat pipe cooled reactor

Yugao Ma,Jiusong Liu,Hongxing Yu,Changqing Tian,Shanfang Huang,Jian Deng,Xiaoming Chai,Yu Liu,Xiaoqiang He 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.6

The solid-state core of a heat pipe cooled reactor operates at high temperatures over 1000 K withthermal and irradiation-induced expansion during burnup. The expansion changes the gap thicknessbetween the solid components and the material properties, and may even cause the gap closure, whichthen significantly influences the thermal and mechanical characteristics of the reactor core. This studydeveloped an irradiation behavior model for HPRTRAN, a heat pipe reactor system analysis code, tointroduce the irradiation effects such as swelling and creep. The megawatt heat pipe reactor MegaPowerwas chosen as an application case. The coupled irradiation-thermal-mechanical model was developed tosimulate the irradiation effects on the heat transfer and stresses of the whole reactor core. The resultsshow that the irradiation deformation effect is significant, with the irradiation-induced strains up to2.82% for fuel and 0.30% for monolith at the end of the reactor lifetime. The peak temperatures during thelifetime are 1027:3 K for the fuel and 956:2 K for monolith. The gap closure enhances the heat transferbut caused high stresses exceeding the yield strength in the monolith

Effects of Electron-beam Irradiation on the Transition Properties of YBa2Cu3O7−d Grain Boundary Junctions

이성훈,이순걸 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.4

We have studied the effects of high-energy electron-beam irradiation on the transition properties of superconducting YBa2Cu3O7−d (YBCO) grain boundary junctions, bicrystal junctions and step-edge junctions, on SrTiO3 substrates. A uniform 1-MeV electron beam irradiated all over the samples. The irradiation doses were 0, 4.7 × 1014, 4.7 × 1015, and 4.7 × 1016 e/cm2. For each junction type, we used at least two samples for each dose level and compared the transition parameters before and after irradiation. For comparison, we also studied the same irradiation effects for YBCO microbridges. We measured the resistive transition temperature, the current-voltage characteristics, the normal-state resistance, and the critical current. The effect of irradiation was the most significant for the bicrystal grain-boundary junction and the least significant for the microbridges. The critical current data for the YBCO bicrystal grain-boundary junction showed a maximum at (0.47 0.9) × 1015 e/cm2, and those for the microbridges showed a monotonic decrease with increasing dose. The normal-state resistance increased monotonically with increasing dose for all samples by up to 40% for the microbridges and 20% for the grain-boundary junctions at 4.7 × 1015 e/cm2. The change in the superconducting temperature (Tc) was negligible except for the bicrystal junction at 4.7 × 1016 e/cm2, which was not superconducting at 77 K. These results show that grain-boundary junctions are more susceptive to irradiation, indicating that their critical currents are controllable by using high-energy electron-beam irradiation.

IRRADIATION EFFECTS OF HT-9 MARTENSITIC STEEL

Chen, Yiren Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.3

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.

Chemical effects at interfaces of Fe/MgO/Fe magnetic tunnel junction

Singh, Jitendra Pal,Kaur, Baljeet,Gautam, Sanjeev,Lim, Weon Cheol,Asokan, Kandasami,Chae, Keun Hwa Elsevier 2016 Superlattices and microstructures Vol.100 No.-

<P><B>Abstract</B></P> <P>Present review focuses the investigation carried out in order to understand the interface structure of magnetic tunnel junction (MTJ) by considering Fe/MgO/Fe as prototype structure. Tunneling magnetoresistence (TMR) of MTJ is affected by the spin polarization of ferromagnetic layers. This phenomena is governed by spin dependent tunneling in perfect MTJ. In MTJ with disordered interface, resonance states through interface play an important role. Some important phenomena like perpendicular magnetic anisotropy, spin transfer torques, and electrical switching are also affected by the interface structure. Apart from disorder and lattice mismatch, interface structure is governed by several factors like oxidation, defects, vacancies as well as hybridization among Fe(3<I>d</I>)-O(2<I>p</I>) states. These effects are categorized as ‘chemical effects’. Due to these factors, contribution from interface resonance states dominates which reduces TMR and related properties. A discussion for determination of these effects are highlighted using several techniques like X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. Simulation results reveal modification of TMR via chemical effects occuring at interface in these MTJ. Thus tailoring of chemical effects in controlled manner is discussed to understand the interface assisted phenomena in these structures. Modification of the chemical effects is induced by irradiation of swift heavy ions, thereby, providing an opportunity to correlate chemical effects and TMR of MTJ.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Interface structure affects spin dependent tunneling. </LI> <LI> Chemical effects are dominant at interfaces. </LI> <LI> These effects can be tailored using swift heavy ion irradiation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Insights from an OKMC simulation of dose rate effects on the irradiated microstructure of RPV model alloys

Li Jianyang,Zhang Chonghong,Martin-Bragado Ignacio,Yang Yitao,Wang Tieshan 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

This work studies the defect features in a dilute FeMnNi alloy by an Object Kinetic Monte Carlo (OKMC) model based on the "grey-alloy" method. The dose rate effect is studied at 573 K in a wide range of dose rates from 108 to 104 displacement per atom (dpa)/s and demonstrates that the density of defect clusters rises while the average size of defect clusters decreases with increasing dose rate. However, the dose-rate effect decreases with increasing irradiation dose. The model considered two realistic mechanisms for producing <100>-type self-interstitial atom (SIA) loops and gave reasonable production ratios compared with experimental results. Our simulation shows that the proportion of <100>-type SIA loops could change obviously with the dose rate, influencing hardening prediction for various dose rates irradiation. We also investigated ways to compensate for the dose rate effect. The simulation results verified that about a 100 K temperature shift at a high dose rate of 1 104 dpa/s could produce similar irradiation microstructures to a lower dose rate of 1 107 dpa/s irradiation, including matrix defects and deduced solute migration events. The work brings new insight into the OKMC modeling and the dose rate effect of the Fe-based alloys.

방사선 조사가 백서 악관절에 미치는 조직병리학적 조기변화에 관한 실험적 연구

윤호중,유동수,Yun Ho-Jung,You Dong-Soo 대한영상치의학회 1993 Imaging Science in Dentistry Vol.23 No.1

The purpose of this study was to investigate the early effects of irradiation on the temporomandibular joint in rats. Male rats were singly irradiated with the dose of 5 Gy or 10 Gy to their head and neck region by /sup 60/Co X ray. Experimental animals were sacrificed at each of the following time intervals -1, 2, 3, 5, 7 and 14 days. The specimens were examined with a light microscope, and treated with H & E staining and immuno-histochemical staining. The results were as follows, 1. By light microscopic findings, proliferative and hypertrophic zone were narrowed and hematopoietic cells were few in number at 5 days after irradiation. Repair signs were seen at 7 days after irradiation when decrease in osteoclast, increase in hematopoietic cells and increase of proliferative zone were noted. The 10 Gy irradiated group showed more severe histopathologic change than the 5 Gy group, and their repair was more slow. 2. In the S -100 antibody, positive cells were examined in the glenoid fossa. Positive cells of irradiated group showed more slight decrease in number than the control group. Low radiosensitivity and slow repair was noted in the glenoid foosa. 3. The interarticular disc was high radioresistant, and any histopathologic changes were not seen in disc. 4. Repair was examined clearly with the response to the antibodies. Especially by 5 days after irradiation 5 Gy group showed S-l00 positive cells in hypertrophic zone next to proliferative zone, chondroitin-4-sulfate positive cell in erosive zone next to hypertrophic zone, type-1 collagen positive cell in subchondral bone.

Electrical conduction and photoresponses of gamma-ray-irradiated single-stranded DNA/single-walled carbon nanotube composite systems

Hong, W.,Lee, E.M.,Kim, D.W.,Lee, Cheol Eui Elsevier 2015 Nuclear instruments & methods in physics research. Vol.349 No.-

<P><B>Abstract</B></P> <P>Effects of gamma-ray irradiation on the electrical conductivity and photoresponse have been studied for single-stranded DNA (ssDNA)/single-walled carbon nanotube (SWNT) composite films. The temperature-dependent electrical conductivity of the ssDNA/SWNT composite films, well described by a fluctuation-induced tunneling model, indicated modification of the barrier for thermally activated conduction by the gamma-ray irradiation. Besides, the photoresponse measurements indicated modified photoexcited charge carrier generation and oxygen photodesorption in the composite systems due to the gamma-ray irradiation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effects of gamma-ray irradiation on single-stranded DNA (ssDNA)/single-walled carbon nanotube (SWNT) composite films. </LI> <LI> Barrier for thermally activated conduction in the composite systems modified by the gamma-ray irradiation. </LI> <LI> Photoresponses reveal photoexcitation and oxygen photodesorption modified by gamma-ray irradiation. </LI> </UL> </P>