• 제목/요약/키워드: Molecular properties

검색결과 3,799건 처리시간 0.037초

분자동역학을 이용한 FCC 나노박막의 탄성계수 연구 (Molecular dynamics study of the elastic moduli of FCC nanofilm)

  • 김원배;조맹효
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회A
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    • pp.1928-1933
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    • 2008
  • In this paper, elastic properties such as Young's modulus and Poisson's ratio of various transition metal nanofilms are calculated for the {100} and {110} surfaces by using molecular dynamics simulation. A new method using $3^{rd}$ order elastic constants and least square method is presented for the calculation of elastic constants. We also introduce analytical method of calculating elastic constants for EAM potential and it's results as the reference value to be compared with the simulation results.

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Molecular System Design for the Acetylcholine Fluorescent Chemosensor

  • 고광락
    • 센서학회지
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    • 제6권6호
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    • pp.508-513
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    • 1997
  • We exploited a new molecular system - acetylcholine (neurotransmitter) detection system as a building block for the perfect molecular information system (sensing membrane of the chemical sensor) - using water soluble calix[n]arene-p-sulfonates which are useful even in aqueous (water/methanol) neutral solution. This achievement is due to several outstanding properties of these calix[n]arene derivatives such as low $pK_{a}$ values, cation-interactions, and high water-solubility, etc.

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CENSUS AND ANALYSIS OF GALACTIC MOLECULAR CLOUDS

  • HOJAEV, A.S.
    • 천문학논총
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    • 제30권2호
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    • pp.107-108
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    • 2015
  • In this project, all available databases of molecular and gas-dust clouds in the Galaxy were cross-identified by taking into account available properties, including position, angular dimensions, velocity, density, temperature and mass. An initial list of about 7000 entries was condensed into a cross-identified all-sky catalogue containing molecular and gas-dust clouds. Some relationships were studied between the main physical features of clouds. Finally, we prepared a complex observing program and address future work for filling in the gaps.

열수 및 알칼리 용액을 이용하여 국산 목재 칩으로부터 선추출한 헤미셀룰로오스의 특성과 이에 따른 수초지 물성 변화 (Characteristics of pre-extracted hemicelluloses from Korean mixed wood by hot water and alkali solution and its effect on handsheet properties)

  • 서동일;이상훈;심규정;이학래;윤혜정
    • 펄프종이기술
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    • 제43권5호
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    • pp.60-67
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    • 2011
  • Hemicelluloses pre-extracted from Korean mixed wood chip were investigated as a wet-end additive. Hemicelluloses dissolved in hot water and alkali solution were isolated by ethyl alcohol precipitation from pre-extractives. They showed molecular weight of 9,000 ~ 27,000 g/mol as revealed by size exclusion chromatography. The reduction of molecular weight through hot water extraction was caused by autohydrolysis. Chemical composition of the hemicelluloses were analyzed with high-performance liquid chromatography and UV-Vis spectroscopy. As the surface charge of isolated hemicelluloses were negative, the adsorption of hemicelluloses onto softwood unbleached kraft pulp fiber was promoted by poly-DADMAC. The physical properties of handsheets increased as the molecular weight of hemicellulose increased. On the other hands, the optical property decreased with hemicellulose adsorption.

메로시아닌 색소 LB막의 상호혼합효과에 의한 J-aggregates 편광특성 (Polarization Properties of J-aggregates by Mutual Mixing Effect in the LB Films of Merocyanine Dyes)

  • 양창헌;김경철;권영수;신훈규
    • 전기학회논문지
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    • 제59권12호
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    • pp.2245-2249
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    • 2010
  • The physical properties of the LB films with merocyanine dyes have been published and attract attention due to the possibility of molecular structure control. The evaluation of the thin films was focused for the purpose of molecular structure control. The molecular structure in the case of the thin films with dyes can be examine by optical absorption spectra measurements. In the result measured by optical absorption spectra, the $[DX]_{1-x}[DO]_x$ LB films shows a large in-plane anisotropy and the transition dipole moment of red-shifted band is preferentially oriented perpendicular to the dipping direction of the film, while that of the blue-shifted band prefers the dipping direction. The spectrum for $0_{\circ}$, $90_{\circ}$-polarized light coincides with the spectrum for non-polarized light and also with the spectrum was observed in the LB film deposited using a fresh solution. These results show that the aging process does not cause a structural change in chromophore but a change in the degree of molecular orientation. In the results, study of the merocyanine dyes LB films using optical absorption spectra would an interesting problem of absorbance peak shifts and mixed components.

DLPC 인지질 단분자막의 변위전류 특성 연구 (I) (A Study on Displacement Current Characteristics of DLPC Monolayer (I))

  • 송진원;이경섭;최용성
    • 전기학회논문지
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    • 제56권1호
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    • pp.117-122
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    • 2007
  • LB method is one of the most interesting technique to arrange certain molecular groups at precise position relative to others. Also, the LB deposition technique can fabricate extremely thin organic films with a high degree of control over their thickness and molecular architecture. In this way, new thin film materials can be built up at the molecular level, and the relationship between these artificial structures and the properties of materials can be explored. In this paper, evaluation of physical properties was made for dielectric relaxation phenomena by the detection of the surface pressures and displacements current on the monolayer films of phospolipid monomolecular DLPC. Lipid thin films were manufacture by detecting deposition for the accumulation and the current was measured after the electric bias was applied across the manufactured MIM device. It is found that the phospolipid monolayer of dielectric relaxation takes a little time and depend on the molecular area. When electric bias is applied across the manufactured MIM device by the deposition condition of phospolipid mono-layer, it wasn't breakdown when the higher electric field to impress by increase of deposition layers.

Synthesis of α-oximinoketones, Precursor of CO2 Reduction Macrocyclic Coenzyme F430 Model Complexes

  • Kim, Gilhoon;Won, Hoshik
    • 한국자기공명학회논문지
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    • 제21권4호
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    • pp.139-144
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    • 2017
  • Ni(II) containing coenzyme F430 catalyzes the reduction of $CO_2$ in methanogen. Macrocyclic Ni(II) complexes with N,O shiff bases have been received a great attention since metal ions play an important role in the catalysis of reduction. The reducing power of metal complexes are supposed to be dependent on oxidoreduction state of metal ion and structural properties of macrocyclic ring moiety that can enhance electrochemical properties in catalytic process. Six different ${\alpha}$-oximinoketone compounds, precursor of macrocyclic ligands used in $CO_2$ reduction coenzyme F430 model complexes, were synthesized with yields over 90% and characterized by NMR. The molecular geometries of ${\alpha}$-oximinoketone analogues were fully optimized at Beck's-three-parameter hybrid (B3LYP) method in density functional theory (DFT) method with $6-31+G^*$ basis set using the ab initio program. In order to understand molecular planarity and substitutional effects that may enhance reducing power of metal ion are studied by computing the structure-dependent $^{13}C$-NMR chemical shift and comparing with experimental results.

A case study of extraplanar molecular gas in a Virgo spiral using the ALMA

  • Lee, Bumhyun;Chung, Aeree
    • 천문학회보
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    • 제41권2호
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    • pp.61.3-62
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    • 2016
  • NGC 4522 is a spiral galaxy located in the Virgo cluster which appears to be undergoing active ram pressure stripping due to the intracluster medium (ICM). What makes this galaxy special is the extraplanar CO gas, some of which coincides with the extraplanar $H{\alpha}$ patches. As one of the few cases where the interstellar molecular gas is thought to have been pushed out from the stellar disk by the ICM, this galaxy provides an opportunity to study the impact of ICM pressure on the dense/star forming gas and its fate in the extraplanar space after stripping. In order to probe detailed molecular gas properties inside and outside the stellar disk and the associated star formation activities, we have observed NGC 4522 in 12CO (1-0) and 13CO (1-0) using the ALMA. We have targeted two regions, one around the center of the galaxy and one centered on the peak of the extraplanar CO, detecting both lines in both regions. Particularly, this is the first case where 13CO gas has been detected outside the stellar disk in a galaxy undergoing ram pressure stripping. In this work, we present preliminary results from the ALMA observations and discuss the evolution of molecular gas properties and star formation activities inside and outside the stellar disk.

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New Phosphorescent Cyclometalated Iridium(III) Complexes with Diphenyl-1,3-oxazolic and 2-(3-Thienyl)pyridine Ligands for LED Applications

  • Kirsyuk, V. V.;Turgambaeva, A. E.;Shim, Jung-Jin;Rhee, Shi-Woo
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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    • pp.174-177
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    • 2003
  • We report four new phosphorescent iridium(III} complexes with 2,4-diphenyl-1,3-oxazole [$Ir(24dpo)_3$], 2,5-diphenyl-1,3-oxazole [$Ir(25dpo)_3$], 2-(3-thienyl) pyridine [$Ir(3thpyh)_3$] and [Ir(3thpy)2(acac)]. Three of them demonstrate good photophysical properties to be used as dopants to organic polymer matrix or to be used "as is" without a host matrix to fabricate OLEDs. Green and yellow light emission was observed for the photoluminescence: 569/525, 549/498 nm and 557,604/533 (solid state/$CH_2Cl_2$ solution) for $Ir(24dpo)_3$, $Ir(3thpyh)_3$ and $Ir(3thpyh)_2$acac respectively. Room temperature luminescent lifetimes are 2.5 and 1.8 ${\mu}s$ and quantum efficiencies 37 and 53%for $Ir(24dpo)_3$ and $Ir(3thpyh)_3$. The complexes are stable in air and sublimable at low pressure without considerable decomposition. Comparison of physicochemical properties of the reported iridium(III) cyclometalated compounds with that known from literature is carried out.

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