• 제목/요약/키워드: Comet

검색결과 480건 처리시간 0.026초

HALE-BOPP 혜성의 CN, C2 분자 생성율 (CN, C2 PRODUCTION RATES OF COMET HALE-BOPP(C/1995 O1))

  • 손동훈;김상준;김주현;김강민;성언창;형식
    • 천문학논총
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    • 제12권1호
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    • pp.99-109
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    • 1997
  • We obtained the CN($\Delta_V=0$) and $C_2(\Delta_V=0,\;\pm1$) spectra of comet Hale-Bopp(C/1995 O1) at the Kyunghee Observatory and Bohyunsan Astronomical Observatory between March 7 and May 12, 1997 The fluxes for each molecular band were measured and then the production rates and column densities of CN and $C_2$ were calculated using a simple model. The resultantproduction rates of CN and $C_2$ are logQ(CN)=27.4 at r=0.94 AU(preperihelion) and $logQ(C_2)=27.3$ at r=0.94 AU(postperihelion), respectively.

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대기부유분진추출물로 야기된 DNA 손상에 대한 Quercetin, Vitamin C 및 Trolox 의 보호효과 (Chemopreventive Effect of Quercetin, Vitamin C and Trolox Against the Organic Extract of Airborne Particulate Matter Induced Genotoxicity in A549 Human Lung Carcinoma Cells)

  • 김남이;허문영
    • 약학회지
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    • 제51권4호
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    • pp.239-245
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    • 2007
  • In order to evaluate the genotoxicity of airborne particulate matter extracted with dichloromethane (APE), the rat microsome mediated (S-9) or DNA repair enzyme treated Comet assays were performed using the single cell gel electrophoresis in A549 human lung carcinoma cells. It was found that the cells interacting with APE showed more DNA single-strand breaks relative to untreated cells. The genotoxicity of APE was increased with the treatment of S-9 mixture. Microsome mediated DNA damage was inhibited by CYP1Al inhibitor, quercetin. The APE also showed oxidative DNA damage evaluated by endonuclease III treatment. Oxidative DNA damage of APE was inhibited by antioxidants such as vita- min C and Trolox. We also found that the vegetables or fruits extract may reduce APE-induced genotoxicity by their anti- oxidant activity and CYP1A1 inhibition.

SYMBOLIC COMPUTING ALGORITHM FOR THE METHOD OF SUCCESSIVE APPROXIMATIONS FOR NEAR-PARABOLIC ORBITS

  • M.A.Sharaf;Abdel-Naby-S.Saad;Samiha-A.Najmuldeen;Mona-Banaja
    • Journal of applied mathematics & informatics
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    • 제4권2호
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    • pp.447-456
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    • 1997
  • In this paper an accurate algorithm for the method of successive approximations for near-parabolic orbits is established symbolically. Numerical applications are given for motion predictions at fifteen epochs between the years 66 to 1835 for Halley's comet. and at fifteen epochs between the years 1417 to 1782 for Encke's comet. Comparisons with the standard Gauss method [4] show that the present algorithm is very accurate and efficient for motion pred-ications of near-parabolic orbits.

헤일밥 혜성의 HCN(J=1-0) 천이선 관측 (OBSERVATIONS OF THE J=1-0 TRANSITION LINE OF HCN IN COMET HALE-BOPP)

  • 김봉규;김효령;조세형;김상준
    • 천문학논총
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    • 제13권1호
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    • pp.129-134
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    • 1998
  • Observations of the J=1-0 transition line of HCN were made at the center of Comet C/1995 O1 (Hale-Bopp) from November, 1996 to April, 1997 with the 14-m radio telescope at the TRAO (Taeduk Radio Astronomical Observatory). From the obtained data, an HCN production rate at each observed date was derived. The rapid variation of the HCN production rate near the perihelion was detected, and it is thought to be caused by jet(s) from the nucleus. The correlation between the visual magnitude and the HCN production rate is found to be $Q_{HCN}=27.03-0.11(m_v-5log{\Delta})$.

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Suppressive Effects of Various Antioxidants on Melamine-induced Oxidative DNA Damage in Human Lymphocytes

  • Park, Seul-Ki;Lee, Mi-Young
    • Molecular & Cellular Toxicology
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    • 제5권3호
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    • pp.243-249
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    • 2009
  • Melamine, which is used to produce melamine resin for various industrial applications, has a high nitrogen content by mass. For this reason, it has been illegally added to foods to increase their apparent protein content. In the present investigation, melamine-induced oxidative damage of human lymphocyte DNA was evaluated by Comet assay. The in vitro oxidative DNA damage caused by melamine increased in a dose-dependent manner. This DNA damage was significantly inhibited by treatment with ascorbate. Moreover, the traditional Korean medicinal herb, named Acanthopanax, red ginseng and green tea markedly reduced the DNA damage. Various edible plant extracts also inhibited melamine-induced oxidative DNA damage in vitro. Melamine enhanced intracellular ROS generation, and this effect was suppressed by treatment with various antioxidants.

Far-ultraviolet Observations of the Comet C/2001 Q4 (NEAT)

  • 임여명;민경욱
    • 천문학회보
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    • 제35권1호
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    • pp.91.2-91.2
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    • 2010
  • We present far-ultraviolet (FUV) observations of comet C/2001 Q4 (NEAT) obtained with Far-ultraviolet Imaging Spectrograph (FIMS, also called SPEAR) around perihelion between 8 and 15 May 2004. Several important emission lines, including S I (1425, 1474 ${\AA}$), C I (1561, 1657 ${\AA}$), CO (1087.9, 1340-1680 ${\AA}$) were detected. Especially, the spectral features of CO are its electronic transitions belongings to the A-X, C-X systems. We also obtained radial profile of S I, C I, H I $Ly{\beta}$ with line fitting from central coma. The production rate of several spectral lines calculated from observed FUV photon flux. FUV spectral images of S I, C I, H I $Ly{\beta}$ emission lines were obtained.

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페난트렌에 의한 임파구 DNA의 산화적 손상과 인삼추출물에 의한 억제 (Phenanthrene-induced Oxidative DNA Damage of Lymphocytes and the Suppression by Ginseng Extract)

  • 유아름;이미영
    • Journal of Ginseng Research
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    • 제33권4호
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    • pp.355-360
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    • 2009
  • Phenanthrene ($C_{14}H_{10}$) is a polycyclic aromatic hydrocarbon with three aromatic rings, and it can be produced by incomplete combustion of fossil fuels. Comet assay was used to examine the oxidative DNA damage of lymphocytes by phenanthrene and to measure the suppressive effects of ginseng extract on the DNA damage in this investigation. The in vitro oxidative DNA damage by phenanthrene increased in a dose-dependent manner in the lymphocyte. However, the DNA damage was significantly inhibited by ascorbate. Moreover, pretreatment, cotreatment and posttreatment with ginseng extract enhanced lymphocyte resistance to the phenanthrene-induced DNA damage. Phenanthrene enhanced the generation of intracellular reactive oxygen species, and the elevated reactive oxygen species level was reduced by treatment with ginseng extract.