• 제목/요약/키워드: Molecular properties

검색결과 3,790건 처리시간 0.031초

Deep Impact: Molecular Gas Properties under Strong Ram Pressure Probed by High-Resolution Radio Interferometric Observations

  • 이범현;정애리
    • 천문학회보
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    • 제44권2호
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    • pp.39.3-39.3
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    • 2019
  • Ram pressure stripping due to the intracluster medium (ICM) is an important environmental process, which causes star formation quenching by effectively removing cold interstellar gas from galaxies in dense environments. The evidence of diffuse atomic gas stripping has been reported in several HI imaging studies. However, it is still under debate whether molecular gas (i.e., a more direct ingredient for star formation) can be also affected and/or stripped by ram pressure. The goal of this thesis is to understand the impact of ram pressure on the molecular gas content of cluster galaxies and hence star formation activity. To achieve this, we conducted a series of detailed studies on the molecular gas properties of three Virgo spiral galaxies with clear signs of active HI gas stripping (NGC 4330, NGC 4402, and NGC 4522) based on high-resolution CO data obtained from the Submillimeter Array (SMA) and Atacama Large Millimeter/submillimeter Array (ALMA). As a result, we find the evidence that the molecular gas disk also gets affected by ram pressure in similar ways as HI even well inside of the stellar disk. In addition, we detected extraplanar 13CO clumps in one of the sample, which is the first case ever reported in ram pressure stripped galaxies. By analyzing multi-wavelength data (e.g., Hα, UV, HI, and CO), we discuss detailed processes of how ram pressure affects star formation activities and hence evolution of cluster galaxies. We also discuss the origin of extraplanar 13CO, and how ram pressure can potentially contribute to the chemical evolution of the ICM.

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New Tactics for Stereospecificity in Metallocene-based Olefin Polymerization

  • Kim, Seong-Kyun;Park, Sung-Jin;Kim, Hwa-Kyu;Yoon, Seung-Woong;Lee, Jun-Seong;Park, Myung-Hwan;Do, Young-Kyu
    • 한국고분자학회:학술대회논문집
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    • 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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    • pp.221-221
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    • 2006
  • The stereochemical control in polypropylenes and styrene-ethylene copolymers based on homogeneous single-site polymerization catalysts has received great attention since the stereocpecificity is one of the key factors in tailoring the polymer properties. Thus, we have developed new tactics for isospecificity in propylene polymerization with the unbridged metallocenebased systems and syndiospecific styrene-styrene sequence in styrene-ethylene copolymerization with the group 4 metallocene system. Brief details of the synthesis, structures and the polymerization behavior of a set of new metallocene catalysts will be presented.

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분자 자성체의 자기 특성과 양자역학적 효과 (The Magnetic Properties and Quantum Effects of Molecular Nanomagnets)

  • 장지훈
    • 한국자기학회지
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    • 제14권2호
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    • pp.83-88
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    • 2004
  • 자성의 양자 역학적 터널 효과의 발견 이후 학술적 관심이 증대된 분자 자성체의 자기적 성질과 양자역학적 효과에 대하여 고찰하였다. 분자 자성체는 유기물 골격 구조 안에 자성 이온이 일정한 구조를 가지고 배열되어 있는 금속-유기물 분자로서, 동일한 구조를 가지는 분자들 간의 자기적 상호작용이 매우 작은 분자들이 거대한 분자-결정을 형성하고 있다. 이러한 이유로 기존의 자성 물질에 비해서 많은 특이한 성질들을 가지고 있는데 특히 거시적 측정의 결과가 미시적인 특성, 즉, 분자의 자기적 성질을 그대로 보여 준다는 점은 매우 흥미롭다. 분자 자성체의 자성에 대해 고찰함에 있어서 미시적인 연구 방법인 핵자기 공명법을 이용한 연구들에 중점을 두고 고찰하였다. Mnl2-ac에서 발견된 자성의 양자적 터널 현상을 핵자기 공명법으로 관측하는 방법에 대하여 연구하였고 그것을 이용한 양자역학적 터널 현상에 대한 미시적 연구도 고찰하였다. 또한 분자 자성체에서 핵자기 공명법으로 처음으로 발견된 레벨간의 교차효과도 그 물리적 의미를 실험 결과들을 가지고 고찰하였다. 이러한 분자 자성체 대한 연구는 향후 응용분야에서 필요할 자기 기억 소자의 크기의 한계에 대한 정보를 줄 수 있고, 양자 컴퓨터에의 응용에 필요한 기초 지식을 제공할 것이다. 학술적인 면에서는 지금까지 잘 이해되지 않고 실험적으로 검증이 되지 않았던 많은 양자역학적 이론들의 실험적 검증이 가능할 것이다.

고분자량 Polyethylene Glycol 처리에 따른 모직물과 유사모직물의 보온성과 태의 향상 방안 모색 (An Approach to Improve Thermal Insulation Properties and Fabric Hand of Wool and Wool-like Fabrics under High Molecular Polyethylene Glycol Treatment)

  • 조길수;이은주
    • 한국의류학회지
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    • 제21권6호
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    • pp.1041-1050
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    • 1997
  • This study was carried out to improve the thermal insulation properties of wool and wool- like fabrics by treating the fabrics with polyethylene glycol, to evaluate the fabric hand of PEG treated wool and wool-like fabrics and to grade up the fabric hand of the treated fabrics by treating with softening agents. Wool and wool-like fabrics were treated with high molecular PEG-8,000 by PDC. The thermal release/storage properties were measured on a DSC. Hand of specimens were evaluated by KES-FB system. The results were as follows; 1. PEG-treated fabrics showed thermal storage and thermal release properties by DSC and the heat contents were generally proportional to the add-ons. 2. PEG-treated fabrics showed higher Koshi and lower Numeri and Sofutosa values due to lower tensile energy and recovery and higher bending rigidity and shear stiffness as the add- ons increased. 3. PEG-treated fabrics showed much lower bending rigidity after softening agents treatment.

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n-Butyl Acrylate/Acrylic Acid 공중합체와 점착부여제간의 상용성과 점착물성 (The PSA Properties of n-Butyl Acrylate/Acrylic Acid Copolymer and Tackifier Resins with Influence of Miscibility)

  • 민경은;김호겸;최관영;곽기호
    • 폴리머
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    • 제24권4호
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    • pp.469-476
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    • 2000
  • 아크릴 공중합체와 점착부여제와의 상용성을 점착제의 물성에 영향을 주었다. 특히 높은 분자량과 좁은 분자량 분포를 가진 아크릴 공중합체가 혼합된 점착제는 상용계에 한해서만 점착 부여제의 함량증가에 따른 체계적인 물성 향상을 보였으며 이들 두 성분간의 상용성을 확인하는 것은 점착제의 물성에 매우 중요하다는 것을 알게 되었다.

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대두단백겔의 물성에 미치는 분자결합력 저해 시약의 영향 (Effects of Various Reagents on Textural Properties of Soy Protein Gel)

  • 배동호;정호선
    • 한국식품저장유통학회지
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    • 제5권1호
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    • pp.65-71
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    • 1998
  • The changes in gel characteristics of soy protein as a result of various reagents that alter specific interactions which affect the formation and textural properties of gels, were studied. The reagents were added to 15% soy protein solutions prior to heat treatment. The gels were not formed with urea, indicating that hydrogen bonds significantly contributed to the formation and hardness of soy protein gel. Hydrophobic interactions and disulfide bonds compensated for hydrogen bonds and the contributions of electrostatic interactions to gel hardness are relatively insignificant. The farce primarily responsible for gel cohesiveness appeared to be disulfide bonds, because a significant decrease in cohesiveness was found only with the presence of N-ethylmaleimide. Adhesiveness decreased only with the addition of urea, and thus the contribution of hydrogen bonding to adhesiveness of gel could be concluded to be resent. However, adhesiveness was suggested to be interpreted not only wile molecular forces involved in gel formation but also with hydration properties of protein.

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Vegetable Fatty Acid Esters에 따른 평판 잉크의 물성 변화에 관한 연구 (The Variation of Offset Ink Properties According to the Vegetable Fatty Acid Esters)

  • 박정민;김성빈
    • 한국인쇄학회지
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    • 제29권3호
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    • pp.1-16
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    • 2011
  • In these days, according to increased environmental regulations, to reduce the VOC content in paints and inks efforts are now in progress. A lot of research have progressed hydrocarbon solvents substitute with vegetable oil or ester in the printing ink but it is restricted to use vegetable oil in the inks because of high molecular weight and viscosity. Oil ester currently developed for printing inks still have some drawbacks, but overall the printability and print quality when using ester than hydrocarbon solvents are showing good results. Thus, in this paper, I studied about the properties variation of the varnish and inks according to vegetable ester, after I reacted vegetable ester using the vegetable fatty acid and ethyl alcohol, butyl alcohol. The compared in order of average molecular weight by the GPC method, rheological properties were found by rotational rheometer, and emulsion behavior were compared by high speed emulsification tester.

Changes of Electrical Properties of Graphene upon Introduction of Structural Defects and Gas Exposure

  • Kim, Kang-Hyun;Kang, Hae-Yong;Lee, Jae-Woo;Lee, Nam-Hee;Woo, Byung-Chill;Yun, Wan-Soo
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2011년도 제40회 동계학술대회 초록집
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    • pp.474-474
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    • 2011
  • Graphene is considered as a potential candidate for the key material in the ideal 2D nanoelectronics. Recently, it is reported that graphene has an interesting sensitivity to molecular adsorption on it. Such properties are believed to be enhanced by the existence of disorders and ripples inside graphene as well as by the interaction with the substrate underneath. Here, we report the effect of introducing structural disorders to the graphene on its electrical properties such as conductance, transconductance, low frequency noise, which can be successfully described by a simple model of the continuum percolation. In addition, the response of the graphene device to gaseous molecular adsorption was systematically investigated and the results were discussed along with the change in Raman spectra.

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CO and HI Properties of the Virgo Cluster Spiral Galaxies

  • Chung, Eun-Jung;Rhee, Myung-Hyun;Kim, Hyo-Ryoung;Chung, Ae-Ree;Yun, Min-S.
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 2009년도 한국우주과학회보 제18권2호
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    • pp.36.1-36.1
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    • 2009
  • We investigate the molecular and atomic gas properties of 20 Virgo cluster spiral galaxies by comparing with optical properties to assess the effect of the Virgo environment on the interstellar media of the Virgo disks. CO maps from FCRAO On-The-Fly (OTF) mapping survey and HI maps from VIVA (VLA Imaging of Virgo spirals in Atomic gas) are shown, and radial properties of molecular and atomic gas are compared. H2 deficiency along with HI is investigated, and gas evolution history of the Virgo cluster spirals is also examined.

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골격근 섬유의 수축성 특성의 다양성 (Diversity of contractile properties in skeletal muscle fibers)

  • 김식현
    • PNF and Movement
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    • 제2권1호
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    • pp.35-47
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    • 2004
  • Purpose : The purpose of this article was to review the literature on contractile properties of skeletal muscle with reference to its molecular and functional diversity. Method : This review outlines scientific findings regarding different contractile properties in skeletal muscle fibers, and discusses their involvement in functional diversity. Result & Conclusions: Muscle fibers possess distinct mechanical and energetic properties. Myosis, one of the primary contractile muscle proteins, displays structural, functional variability and plays the role of the molecular motor of muscle contraction. Muscle satellite cells are normally mitotically quiescent, but initiate proliferation and give rise to daughter myogenic precursor cells as required for the postnatal growth and regeneration of adult muscle. Passive extensibility is an important component of total muscle function because it allows for the maximal length of skeletal muscles. Proprioceptive neuromuscular facilitation(PNF) stretching can help to restore or improve flexibility and coordination, thereby improving overall muscle function.

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