• Title, Summary, Keyword: carbon-ion irradiation

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Telomere-Mitochondrion Links Contribute to Induction of Senescence in MCF-7 Cells after Carbon-Ion Irradiation

  • Miao, Guo-Ying;Zhou, Xin;Zhang, Xin;Xie, Yi;Sun, Chao;Liu, Yang;Gan, Lu;Zhang, Hong
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.4
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    • pp.1993-1998
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    • 2016
  • The effects of carbon-ion irradiation on cancer cell telomere function have not been comprehensively studied. In our previous report cancer cells with telomere dysfunction were more sensitive to carbon-ion irradiation, but the underlying mechanisms remained unclear. Here we found that telomerase activity was suppressed by carbon-ion irradiation via hTERT down-regulation. Inhibition of telomere activity by MST-312 further increased cancer cell radiosensitivity to carbon-ion radiation. hTERT suppression caused by either carbon-ion irradiation or MST-312 impaired mitochondrial function, as indicated by decreased membrane potential, mtDNA copy number, mitochondrial mass, total ATP levels and elevated reactive oxygen species (ROS). PGC-$1{\alpha}$ expression was repressed after carbion-ion irradiation, and hTERT inhibition by MST-312 could further exacerbate this effect. Lowering the mitochondrial ROS level by MitoTEMPO could partially counteract the induction of cellular senescence induced by carbon-ion radiation and MST-312 incubation. Taken together, the current data suggest that telomere-mitochondrion links play a role in the induction of senescence in MCF-7 cells after carbon-ion irradiation.

Tribological Characteristics of Carbon Fiber Reinforced Plastics by Surface modification (탄소섬유복합재의 표면개질에 따른 트라이볼로지 특성에 관한 연구)

  • 전승흥;양준호;오성모;이봉구
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.29-36
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    • 2000
  • This investigation has been studied about friction and wear properties which were important problem, when carbon fiber reinforced plastic(CFRP) was used practically. Unidirection carbon fiber reinforced composites was fabricated with epoxy resin matrix and carbon fiber as a reinforced, and its surface was modified by the ion-assisted reaction. And then we tested the their friction and wear properties according to the ion-irradiation. when the amount of ion-irradiation was 1${\times}$10l6$\^$16/ ions/$\textrm{cm}^2$, the friction coefficient values were about 0.1, where as, the friction coefficient values of non-treatment composites were about 0.16. The former was the stablest in wear mode. We know that ion-irradiation was not proportioned to the friction coefficient, so we found the optimal conditions of the friction and wear according to the ion-irradiation.

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A Study on the Friction and Wear Characteristics of Carbon Fiber Reinforced Plastics by Surface Modification (표면개질에 따른 탄소섬유복합재의 마찰마모 특성에 관한 연구)

  • O, Seong-Mo;Lee, Bong-Gu
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.8
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    • pp.122-128
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    • 2001
  • The objective of the present study was to investigate the characteristics of the friction and wear according to the amount of ion-irradiation for the carbon fiber reinforced plastic(CFRP). Unidirectional carbon fiber reinforced composites were fabricated with epoxy resin as a matrix and carbon fiber as a reinforcement, and its surface was modified by the ion-assisted reaction. When the amount of ion-irradiation was $1{\times}10^{16}$ ions/$cm^2$, the friction coefficients of composites were about 0.1 and the wear mode was stable, whereas, the friction coefficient of non-treatment composites were about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was $5{\times}10^{16}$ ions/$cm^2$, the friction coefficients were higher rather than that of $1{\times}10^{16}$ ions/$cm^2$. Consequently, the amount of ion-irradiation was not in proportion to the friction coefficients, and it was conformed that the optimal conditions would exist between broth of them.

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Tribological Characteristics of Surface Modification by Carbon Fiber Reinforced Plastics (탄소섬유복합재의 표면개질에 따른 트라이볼로지 특성에 관한 연구)

  • Kim, Jong-Hee;Jeon, Seung-Hong;Lee, Bong-Goo;Oh, Seong-Mo
    • Tribology and Lubricants
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    • v.18 no.1
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    • pp.61-67
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    • 2002
  • The objective of the present study was to investigate the characteristics of the friction and wear according to the amount of ion-irradiation for the carbon fiber reinforced plastic (CFRP). Unidirectional carbon fiber reinforced composites were fabricated with epoxy resin as a matrix and carbon fiber as a reinforcement, and its surface was modified by the ion-assisted reaction. When the amount of ion-irradiation was $1{\times}10^{16}$ $ions/cm^{2}$. the friction coefficients of composites were about 0.1 and the wear mode was stable. whereas, the friction coefficient of non-treatment composites were about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was $5{\times}10^{16}$ $ions/cm^{2}$, the friction coefficients were higher rather than that of $1{\times}10^{16}$ $ions/cm^{2}$ Consequently. the amount of ion-irradiation was not in proportion to the friction coefficients, and it was conformed that the optimal conditions would exist between both of them.

Tribological Characteristics of Carbon Fiber Reinforced Plastics Prepared by Ion-Assisted Reaction (이온도움반응법에 의한 탄소섬유복합재의 트라이볼로지 특성연구)

  • 오성모;김정기;이봉구
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.4
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    • pp.103-108
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    • 2004
  • Carbon fiber reinforced composites(CFRP) were fabricated with phenolic resin matrix by hot press molding, and its surface was modified by the ion-assisted reaction process. When we tested the friction coefficient and wear rate variation and observed the effect of fibers with respect to friction and wear characteristics, the amount of pitch based carbon fiber was 45wt% and the average friction coefficient was the lowest at 0.12. When the amount of ion-irradiation was $1\times10^{l6}ions/cm^2$, the friction coefficient of the composites was about 0.12 and the wear mode was stable, whereas, the friction coefficient of the non-treated composites was about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was $5\times10^{l6}ions/cm^2$$1\times10^{l6}ions/cm^2$ion-irradiation case.

A study on liquid crystal alignment characteristics by the properties of hydrogenated amorphous carbon thin films (a-C:H 박막의 물성 변화에 따른 액정 배향 특성에 관한 연구)

  • Lee, Dae-Kyu;Rho, Soon-Joon;Baik, Hong-Koo;Hwang, Jeoung-Yeon;Cho, Yong-Min;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.839-844
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    • 2002
  • This letter focuses on the liquid crystal alignment characteristics according to the properties of hydrogenated amorphous carbon(a-C:H) thin film deposited by RPECVD(Remote Plasma Enhanced Chemical Vapor Deposition) method using $C_2H_2$ and He gases. The properties of the deposited thin films were controlled by the ion beam irradiation time and ion beam energy. The results show that not ion beam energy but ion beam irradiation time plays an important role in the properties of a-G:H thin films. As the ion beam irradiation time increases, not only the sp2 concentration in a-G:H thin films but also liquid crystal pretilt angle was varied.

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Multidirectional Liquid Crystal Orientation by Using Ion Beam Irradiation

  • Ahn, Han-Jin;Kim, Kyung-Chan;Kim, Jong-Bok;Hwang, Byung-Har;Baik, Hong-Koo
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.543-546
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    • 2005
  • We have investigated the alignment ability of multi-domains by using ion beam irradiation on diamond-like carbon (DLC) thin film layers. The DLC thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) system and the low energy ion beam is irradiated from Kaufman type ion gun. The direction of liquid crystal alignment is varied by the direction of Ar ion beam irradiation.

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Enhanced Field Emission and Luminescent Properties of Straightened Carbon Nanotubes to be Applied in Field Emission Display

  • Lee, Hyeong-Rag;Kim, Do-Hyung;Kim, Chang-Duk;Jang, Hoon-Sik
    • Journal of Information Display
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    • v.4 no.2
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    • pp.35-42
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    • 2003
  • The field emission and luminescent properties of carbon nanotubes (CNTs) that were straightened by argon ion irradiation were investigated. Argon ion irradiation permanently straightened both as-grown and screen-printed CNTs (SP-CNTs) in the presence of a strong electric field. The straightening process enhanced the emission properties of as-grown CNT films by showing a decrease in turn-on field, an increase in total emission current, and a stable emission. Recurring problems associated with SP-CNTs, such as bent or/and buried CNTs and the degradation in binder-residue-induced emission, were improved by the permanent straightening of CNTs and protruding CNTs from binders by the irradiation treatment, in addition to its surface cleaning effect. Furthermore, we confirmed that the number of emission sites increases by observing the luminescent properties of CNT films after the straightening. These findings here suggest that ion irradiation treatment is an effective method for achieving uniform field emission and to reduce the electrical aging time.

Liquid Crystal Alignment Effects on Nitrogen-doped Diamond like Carbon Layer by Ion Beam Alignment Method

  • Han, Jeong-Min;Choi, Sung-Ho;Kim, Byoung-Yong;Han, Jin-Woo;Kim, Jong-Hwan;Kim, Young-Hwan;Hwang, Jeoung-Yeon;Lee, Sang-Keuk;Ok, Chul-Ho;Seo, Dae-Shik
    • Transactions on Electrical and Electronic Materials
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    • v.8 no.1
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    • pp.46-50
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    • 2007
  • We have studied the nematic liquid crystal (NLC) alignment effects on a nitrogen-doped diamond-like carbon (NDLC) thin film layer with ion beam irradiation. The pretilt angle for NLC on the NDLC surface with ion beam exposure was observed below 1 degree. Also, we had the good LC alignment characteristics on the NDLC thin films with ion beam exposure of 1800 eV. In thermal stability experiments, the alignment defect of the NLC on the NDLC surface with ion beam irradiation above annealing temperature of $250^{\circ}C$ can be observed. Therefore, the good thermal stability and LC alignment for NLC by ion beam aligned NDLC thin films can be achieved.

Preparation of photoresist-derived carbon micropatterns by proton ion beam lithography and pyrolysis

  • Nam, Hui-Gyun;Jung, Jin-Mook;Hwang, In-Tae;Shin, Junhwa;Jung, Chang-Hee;Choi, Jae-Hak
    • Carbon letters
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    • v.24
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    • pp.55-61
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    • 2017
  • Carbon micropatterns (CMs) were fabricated from a negative-type SU-8 photoresist by proton ion beam lithography and pyrolysis. Well-defined negative-type SU-8 micropatterns were formed by proton ion beam lithography at the optimized fluence of $1{\times}10^{15}ions\;cm^{-2}$ and then pyrolyzed to form CMs. The crosslinked network structures formed by proton irradiation were converted to pseudo-graphitic structures by pyrolysis. The fabricated CMs showed a good electrical conductivity of $1.58{\times}10^2S\;cm^{-1}$ and a very low surface roughness.