• Title/Summary/Keyword: Intense laser science

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An immunohistochemical study on the effects of low-level laser irradiation on expression of actin filaments of human gingival fibroblasts in vitro (저출력레이저조사가 배양치은섬유아 세포의 actin filaments발현에 미치는 영향에 관한 면역조직화학적 연구)

  • Kim, Hyung-Sung;Kim, Chun-Suk;Kim, Hyung-Soo;Kim, Hyun-Seop;Kim, Byung-Ock;Han, Kyung-Yoon
    • Journal of Periodontal and Implant Science
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    • v.26 no.4
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    • pp.1003-1012
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    • 1996
  • The induction of a phenotype with preoperties may have clinical significance in the acceleration of the wound-healing process. Wound contraction involves a specialized cell known as the myofibroblast. The myofibroblasts can be identified by their intense staining of actin bundles with anti-actin antibody. Tissue-specific actin distribution is correlated with the contractile activity of the myofibroblasts and smooth muscle etc. This study was performed to determine the expression of actin filaments in the cytoplasm of cultured human gingival fibroblsts after GaAs laser(BIOSAER, Korea) irradiation. Human gingival fibroblasts were cultured from explants of normal interdental gingival tissue. The third-generation fibroblasts were used for immunohistochemical study. The cultured fibroblasts were exposed $0.53joule/cm^2$(lmW, 7 mimutes) of energy density, and then observed by immunohistochemical method using, rabbit anti0gelsolin, hen smooth muscle polyclonal antibody(Chemicon international inc.), and biotinylated goat anti-rabbit IgG(Vectastain) 24-, 36-, 48-hour after laser irradiation Following results were obtained ; 1. In nonirradiated cultures, round shaped active fibroblasts with abundant cytoplasm and prominet nucleoli were observed. 2. In 24- and 36-hour cultures after laser irradiation, spindle shaped cells with long process were observed. The intensity of stain was seen in cytoplasm of these modified fibroblasts. 3. In 48-hoour cultures after laser irradiation, stained spindle shape cell were not observed. The results suggest that the effect of the galium-arsenide laser treatment on cultured gingival fibroblasts is the rapid development of cytoplasmic actin filaments.

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Joule-heating Induced Crystallization (JIC) of Amorphous Silicon Films

  • Ko, Da-Yeong;Ro, Jae-Sang
    • Journal of the Microelectronics and Packaging Society
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    • v.25 no.4
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    • pp.101-104
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    • 2018
  • An electric field was applied to a Mo conductive layer in the sandwiched structure of $glass/SiO_2/Mo/SiO_2/a-Si$ to induce Joule heating in order to generate the intense heat needed to carry out the crystallization of amorphous silicon. Polycrystalline silicon was produced via Joule heating through a solid state transformation. Blanket crystallization was accomplished within the range of millisecond, thus demonstrating the possibility of a new crystallization route for amorphous silicon films. The grain size of JIC poly-Si can be varied from few tens of nanometers to the one having the larger grain size exceeding that of excimer laser crystallized (ELC) poly-Si according to transmission electron microscopy. We report here the blanket crystallization of amorphous silicon films using the $2^{nd}$ generation glass substrate.

Coherent Diffraction Imaging at PAL-XFEL

  • Kim, Sangsoo;Nam, Kihyun;Park, Jaehyun;Kim, Kwangoo;Kim, Bongsoo;Ko, Insoo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.85.2-85.2
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    • 2016
  • With the advent of ultra-short high-intense XFEL (X-ray Free Electron Laser), time-resolved dynamics has become of great importance in exploring femtosecond real-world phenomena of nanoscience and biology. These include studying the response of materials to femtosecond laser excitation and investigating the interaction of XFEL itself with condensed matter. A variety of dynamic phenomena have been investigated such as radiation damage, ultrafast melting process, non-equilibrium phase transitions caused by orbital-lattice-spin couplings. As far as bulk materials are concerned, the sample size has no effect on the following dynamic process. As a result, imaging information is not required by and large. If the sample size is of tens of nanometers, however, sample starts to experience quantum confinement effect which, in turn, affects the following dynamic process. Therefore, to understand the fundamental dynamic phenomena in nano-science, time-resolved imaging information is essential. In this talk, we will briefly introduce scientific highlights achieved in XFEL-based dynamics. In case of bio-imaging, recent scientific topics will be mentioned as well. Finally, we will aim to present feasible topics in ultrafast time-resolved imaging and to discuss the future plan of CXI beamline at PAL-XFEL.

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Irradiation of Intense Characteristic X-rays from Weakly Ionized Linear Plasma

  • Sato, Eiichi;Hayasi, Yasuomi;Tanaka, Etsuro;Mori, Hidezo;Kawai, Toshiaki;Takayama, Kazuyoshi;Ido, Hideaki
    • Proceedings of the Korean Society of Medical Physics Conference
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    • 2002.09a
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    • pp.396-399
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    • 2002
  • Intense quasi-monochromatic x-ray irradiation from the linear plasma target is described. The plasma x-ray generator employs a high-voltage power supply, a low-impedance coaxial transmission line, a high-voltage condenser with a capacity of about 200 nF, a turbo-molecular pump, a thyristor pulse generator as a trigger device, and a flash x-ray tube. The high-voltage main condenser is charged up to 55 kV by the power supply, and the electric charges in the condenser are discharged to the tube after triggering the cathode electrode. The x-ray tube is of a demountable triode that is connected to the turbo molecular pump with a pressure of approximately 1 mPa. As electron flows from the cathode electrode are roughly converged to the molybdenum target by the electric field in the tube, the weakly ionized plasma, which consists of metal ions and electrons, forms by the target evaporating. In the present work, the peak tube voltage was almost equal to the initial charging voltage of the main condenser, and the peak current was about 20 kA with a charging voltage of 55 kV. When the charging voltage was increased, the linear plasma x-ray source grew, and the characteristic x-ray intensities of K-series lines increased. The quite sharp lines such as hard x-ray lasers were clearly observed. The quasi-monochromatic radiography was performed by a new film-less computed radiography system.

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