12,570 research outputs found
Monte Carlo simulation of anisotropic grain growth in liquid phase sintering
No full textOne of the key techniques in modern engineering ceramic system is microstructural control of anisotropic grain growth because grain orientation and shape proved to have an influence on mechanic, dielectric and electric behavior of ceramics. But until now, computer simulation for grain growth has not sufficiently addressed to this subject. The reason is that simulation algorithm was laborious because it has to contain mass transfer through liquid phase and especially anisotropic grain growth has to be considered based on interfacial properties in real system. The goal of present study is simulation of anisotropic grain growth in liquid phase by Q-states model. To give anisotropic inherency to grains, constraint on mobility to specific boundaries was applied. For comparison, we measured grain size distribution and deduced grain growth kinetics from relationship between average grain size and time. As a result, the grain size distribution functions become broader and the peak height decreases as the anisotropy is increased. The growth exponent 0.67 and 0.47 found by linear fitting have slightly different values in comparison with work of Grest et al. but similar is trend to the decrease of exponent with anisotropy
New half-sandwich metallocene catalysts for polyethylene and polystyrene
No full textA new type of half-sandwich metallocene catalysts for the polymerization of ethylene and styrene, Cp*MCl(DEA-R) (DEA = (OCH2CH2)(2)N, R = Me, M = Ti (1); R = Me M = Zr (2); R = n-Bu, M = Ti (3)), was prepared by the reaction of corresponding N-alkyl-N,N-diethanolamine with Cp*MCl3 in the presence of triethylamine. Compounds 1-3 are slightly air-sensitive and thermally unstable. All catalyst systems show moderate activities in ethylene polymerization and especially the 2/MMAO system gives PE with broad molecular weight distribution at all polymerization temperatures. In addition, 1/MMAO and 3/MMAO show fairly good activities in sPS polymerization in the order 3/MMAO > 1/MMAO. (C) 2001 Elsevier Science B.V. All rights reserved.Korea Science and Engineering Foundation via CMD
O ethos coreano: a forma expressa do Han no cinema de Kim Ki-Duk
No full textHan is a term present in Korean culture used to describe a unique feeling linked to the
country's history and the experience of its people. The manifestation of the han accompanies Korean society from the period of domination by Japan, through the military governments and to the present day. The present work aims to identify if there is a materialization of the concept of han and in what way it is expressed in the audiovisual works of the South Korean director Kim Ki-duk. To this end, a bibliographic review of authors related to the subject was carried out, as well as a film analysis of Kim Ki-duk's works “3-Iron” (Bin-jip, 2004), “Spring, Summer, Fall, Winter... and Spring” (Bom yeoreum gaeul gyeoul geurigo bom, 2003) and “Amen” (2011). From this perspective, the han proved to be articulable both through the narrative aspect and in the elaboration of the formal language of these works by the director.O han é um termo presente na cultura coreana utilizado para descrever um sentimento único ligado à história do país e vivência de seu povo. A manifestação do han acompanha a sociedade da Coreia desde o período de dominação pelo Japão, passando pelos governos militares e até os dias atuais. O presente trabalho objetiva identificar se há a materialização do conceito de han e por qual forma ele é expresso nas obras audiovisuais do diretor sul-coreano Kim Ki-duk. Para tal fim, foi realizada a análise fílmica das obras de Kim Ki-duk “Casa Vazia” (Bin-jip, 2004), “Primavera, Verão, Outono, Inverno... e Primavera” (Bom yeoreum gaeul gyeoul geurigo bom, 2003) e “Amen” (2011). Sob essa ótica, o han se mostrou articulável tanto através do aspecto narrativo quanto na elaboração da linguagem formal dessas obras do diretor
New titanatranes: Characterization and styrene polymerization behavior
No full textNew titanatranes containing cyclopentadienyl ligands were prepared by the reactions of various kinds of trialkanolamines with (C5Me4R)TiCl3 (Cp' = C5Me4R) in the presence of triethylamine. The X-ray analyses reveal that they exist in the monomeric form in the solid state and the Ti atom adopts essentially an eta(5) bonding posture with the Cp' ring and a tetradentate bonding mode with the trialkanolatoamine ligand via a transannular interaction from the bridgehead N atom to Ti. All compounds show very high catalytic activity for the syndiospecific polymerization of styrene in the presence of modified methylaluminoxane (MMAO) cocatalyst.We gratefully acknowledge financial
support from the Korea Science and Engineering
Foundation and the Brain Korea 21 Project
The Effects of Consumer Knowledge on Message Processing of Electronic Word of Mouth via Online Consumer Reviews
No full textEffects of Substrate Morphology on Adhesion and Pore Structure of Cu foam Prepared by Electrodeposition
No full textMorphology evolution of anatase TiO2 nanocrystals under a hydrothermal condition (pH=9.5) and their ultra-high photo-catalytic activity
No full textMorphology evolution of anatase TiO2 nanocrystals under a hydrothermal condition (pH = 9.5) was observed and a relationship between the morphology evolution and photo-catalytic activity was investigated. A titanium hydroxide nanogel was neutrally precipitated from a TiCl4 aqueous solution and then used as the precursor in the hydrothermal process. In the hydrothermal process, the nanogel was finally crystallized and grew to a capped bipyramidal nanocrystal which has faceted {101} pyramidal faces and are capped with rounded (001) faces, passing through an elongated structure with zigzag {101} faces. The final morphology was evolved via four growth stages in series: (i) formation and growth of anatase nuclei with consuming the nanogel, (ii) rapid growth along [0 0 1] direction by oriented attachments between (0 0 1) faces to produce an elongated structure with zigzag {101} pyramidal faces, (iii) flattening of zigzag {101} pyramidal faces by solution and precipitation, and (iv) rapid growth along [0 0 1] direction by solution and precipitation (Ostwald ripening). The photo-catalytic activity of anatase nanocrystals was closely related to the morphology evolution. Especially, the capped bipyramidal nanocrystals in the last growth stage showed an excellent photo-catalysis behavior: some of them were more than three times active than a commercial photo-catalyst (P25). The ultra-high photo-catalytic activity originated in the well-developed {101} surfaces, since the 4-coordinated Ti ions in the step edge of {101} face effectively adsorbed hydroxyl ions. Therefore, the particle morphology (surface property) was important as much as the particle diameter in TiO2 photo-catalysis. (c) 2005 Elsevier B.V. All rights reserved.The present work was financially supported in part by
the Research Institute of Industrial Science and Technology
(RIST) and in part by the Center for Nanostructured Materials
Technology (CNMT), Korea
Enhanced efficiency of organic light-emitting diodes using TiO2 nanoparticles via a microcavity effect
No full textVibration Measurement and Flutter Suppression Using Patch-type EFPI Sensor System
No full textAn optical phase tracking technique for an extrinsic Fabry-Perot interferometer (EFPI) is proposed in order to overcome interferometric non-linearity. Basic idea is utilizing strain-rate information, which cannot be easily obtained from an EFPI sensor itself. The proposed tracking system consists of a patch-type EFPI sensor and a simple on-line phase tracking logic. The patch-type EFPI sensor comprises an EFPI and a piezoelectric patch. An EFPI sensor itselp has non-linear behavior due to the interferometric characteristics, and a piezoelectric material has hysteresis. However, the composed patch-type EFPI sensor system overcomes the problems that that can arise when they are used individually. The dynamic characteristics of the proposed phase tracking system were investigated, and then the patch-type EFPI sensor system was applied to the active suppression of flutter, dynamic aeroelastic instability, of a swept-back composite plate structure. The proposed system has effecttively reduced the amplitude of the flutter mode, and increased flutter speed
Synthesis and characterization of group 4 constrained geometry complexes containing a linked cyclopentadienyl-o-carboranyl ligand
No full textNovel linked cyclopentadienyl-o-carboranyl group 4 metal complexes, [eta (5):eta (1)-Me2Si(C5Me4)(C2B10H10]TiCl2 (2) and [eta (5):eta (1)-Me2Si(C5Me4)(C2B10H10)]Zr(NMe2)(2) (3), have been prepared via salt metathesis and amine elimination. reactions utilizing the linked o-carboranyl ligand, Me2Si(C5Me4H)(C2B10H11) (1). Their X-ray crystal structures are reported.The financial support from the
Korea Science and Engineering Foundation and the
Brain Korea 21 Project are gratefully acknowledged
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