• Title/Summary/Keyword: Opal

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Synthesis of polymer - based inverted opal and transformation of its optical properties

  • Masalov, Vladimir M.;Dolganov, Pavel V.;Sukhinina, Nadezhda S.;Dolganov, Vladimir K.;Emelchenko, Gennadi A.
    • Advances in nano research
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    • v.2 no.1
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    • pp.69-76
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    • 2014
  • We have obtained opal-like photonic crystals based on opals and inverted opals exhibiting a shift of the selective reflection band toward longer and shorter wavelengths with respect to the diffraction band of the initial opal consisting of $SiO_2$ spheres. The contribution of frames forming three-dimensional periodic structures and that of fillers to the spectral arrangement of the diffraction bands has been determined.

THE OPAL (OPEN POOL AUSTRALIAN LIGHT-WATER) REACTOR IN AUSTRALIA

  • Kim Sung-Joong
    • Nuclear Engineering and Technology
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    • v.38 no.5
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    • pp.443-448
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    • 2006
  • The OPAL (Open Pool Australian Light-water) reactor is currently being constructed to replace HIFAR (HI-Flux Australian Reactor, commissioned in 1958) in mid-2006. HIFAR will be shutdown for decommissioning after several months of simultaneous operation with OPAL for smooth transition of operating systems and business. OPAL is a 20 MW multipurpose research reactor for radioisotope production, irradiation services and neutron beam research. The OPAL reactor uses low enriched uranium fuel in a compact core, cooled by light water and moderated by heavy water, yielding maximum thermal flux not less than $4{\times}10^{14}ncm^{-2}s^{-1}$. The reactor containment building is constructed of reinforced concrete and has been designed to protect the reactor from all external events such as seismic occurrences and impact from a hypothetical light aircraft crash. This paper describes the main elements of the reactor design and its applications.

Eelectro-optic Behavior of Opal-LC Photonic Crystals

  • Kang, Dae-Seung
    • Journal of Information Display
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    • v.2 no.4
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    • pp.19-22
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    • 2001
  • In this paper, we describe the electro-optic effects of photonic crystals made of a synthetic opal filled with a nematic liquid crystal(LC). By applying an external electric field, a shift in the Bragg reflection peak position(stop band) and a field-induced change in its peak reflectivity are observed. These significant surface alignment effects of the opal-LC composite are discussed in a similar manner for Freederick-type transitions of LC within a confined geometry in the presence of external fields.

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Biogenic Opal Production and Paleoclimate Change in the Wilkes Land Continental Rise (East Antarctica) during the Mid-to-late Miocene (IODP Exp 318 Site U1359) (동남극 윌크스랜드 대륙대의 마이오세 중-후기 동안 생물기원 오팔 생산과 고기후 변화(IODP Exp 318 Site U1359))

  • Song, Buhan;Khim, Boo-Keun
    • Ocean and Polar Research
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    • v.37 no.1
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    • pp.23-35
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    • 2015
  • A 450 m-long sediment section was recovered from Hole U1359D located at the eastern levee of the Jussieau submarine channel on the Wilkes Land continental rise (East Antarctica) during IODP Expedition 318. The age model for Hole U1359D was established by paleomagnetic stratigraphy and biostratigraphy, and the ages of core-top and core-bottom were estimated to be about 5 Ma and 13 Ma, respectively. Biogenic opal content during this period varied between 3% and 60%. In the Southern Ocean, high biogenic opal content generally represents warm climate characterized by the increased light availability due to the decrease of sea-ice distribution. The surface water productivity change in terms of biogenic opal content at about 10.2 Ma in the Wilkes Land continental rise was related to the development of Northern Component Water. After about 10.2 Ma, more production of Northern Component Water in the North Atlantic caused to increase heat transport to the Southern Ocean, resulting in the enhanced diatom production. Miocene isotope events (Mi4~Mi7), which are intermittent cooling intervals during the Miocene, appeared to be correlated to the low biogenic opal contents, but further refinement was required for precise correlation. Biogenic opal content decreased abruptly during 6 Ma to 5.5 Ma, which most likely corresponds to the Messinian salinity crisis. Short-term variation of biogenic opal content was related to the extent of sea-ice distribution associated with the location of Antarctic Polar Front that was controlled by glacial-interglacial paleoclimate change, although more precise dating and correlation will be necessary. Diatom production in the Wilkes Land continental rise increased during the interglacial periods because of the reduced sea-ice distribution and the southward movement of Antarctic Polar Front.

Mineral Composition of the Sediment of Ulleung Basin, Korea (울릉분지 퇴적물의 광물조성)

  • Son, Byeong-Kook;Kim, Hag-Ju;Ahn, Gi-Oh
    • Journal of the Mineralogical Society of Korea
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    • v.22 no.2
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    • pp.115-127
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    • 2009
  • Mineral quantification was performed on sediments of the Ulleung basin by X-ray powder diffraction and the computer software based on Rietveld quantification method. The sediments are dominated by amorphous opal-A with quartz, feldspars, micas, clays, calcite, and pyrite. The opal-A shows iterative variation in abundance with increasing burial depth. In addition, the relative abundance of opal-A is coincident with abundance of organic carbon contents, indicating that the Ulleung sediment consists mostly of amorphous silica derived from organism in the pelagic environment. Upward increase in the abundance of opal-A is markedly shown in the cores located in the slope region. On the other hand, there is a distinct tendency that the abundance of calcite is inversely proportional to that of opal-A. This indicates that the abundance of opal-A increases during the rise of sea level. Also, the fall of sea level lowers the abundance of opal-A.

색깔 변환이 가능한 삼차원 포토닉 액추에이터

  • Jeong, Gwang-Un;Lee, Myeong-Hun;Na, Chang-Un;Jin, Gwang-Yong
    • Rubber Technology
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    • v.9 no.1
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    • pp.25-28
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    • 2008
  • By combining the multi-faceted environmental responsiveness of polymer hydrogels with photonically active structures, there has been a significant effort to create color-tunable photonic crystal sensors by changing either the periodic spacing of the structure or the dielectric constants of the materials. Here, we show that reversible spiral and helical opal switches with both dimensional and optical functionalities that respond to environmental chemistry can be constructed. When the transparent opal switch is swollen in hydrophilic acetic acid, right-handed spirals and helices that exhibit angularly dependent colors from Bragg diffraction are formed. When the transparent opal switch is swollen in hydrophobic hexane, left-handed spirals which exhibit angularly dependent colors from Bragg diffraction are formed. When the transparent opal switch is swollen in hydrophobic hexane solvent, a left-handed spiral and helix with an angularly independent bluish color is formed. After deswelling, all switches returned back to the transparent planar state. These color-tunable, reversible spiral and helical opal switches can be useful as mechanical actuators, and electrical devices as well as optical components.

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Fabrication of Three-Dimensional Magnetophotonic Crystals:Opal Thin Films Filled with Bi:YIG

  • Fujikawa, R.;Baryshev, A.V.;Uchida, H.;Lim, P.B.;Inoue, M.
    • Journal of Magnetics
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    • v.11 no.3
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    • pp.147-150
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    • 2006
  • We have fabricated three-dimensional magnetophotonic crystals based on $\alpha$-$SiO_2$ opal films. Opal thin films grown on glass substrates were filled with bismuth substituted iron garnet (Bi:YIG). Scanning electron microscopy data, optical and magnetic properties of the synthesized samples confirm the presence of the Bi:YIG contentin the opal lattice. It is shown that the samples exhibit the (111) stop band, and transmissivity of the threedimensional magnetophotonic crystals is defined by both the film lattice and the Bi:YIG content.

Enhanced Chondrogenic Differentiation of Human Adipose-derived Stem Cells with Inverse Opal Scaffolds (역오팔 구조 지지체를 이용한 인간 지방 유래 줄기 세포의 연골 분화 촉진)

  • Bhang, Suk Ho;Yu, Taekyung
    • Korean Chemical Engineering Research
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    • v.51 no.6
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    • pp.727-732
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    • 2013
  • In this report, we present an inverse opal scaffold that can enhance the chondrogenic differentiation of human adipose-derived stem cells (hADSCs) without drug, gene, or cytokine supplement. Inverse opal scaffolds based on poly(D,L-lactide-co-glycolide) were formed with uniform $200{\mu}m$ pores. Due to uniform pore sizes and well-controlled interconnectivity of inverse opal scaffold, hADSCs were allowed to distribute homogeneously throughout the scaffolds. As a result, high cell density culture with scaffold was possible. Since the hADSCs cultured in inverse opal scaffolds were subjected to limited supplies of oxygen and nutrients, these cells were naturally preconditioned to a hypoxic environment that stimulated the up-regulation of hypoxia-inducible factor-$1{\alpha}$ (HIF-$1{\alpha}$). As a result, apoptotic activity of hADSCs until 3 weeks after initial cell seeding was significantly reduced and chondrogenic differentiation related molecular signal cascades were up regulated (transforming growth factor-beta, phosphorylated AKT, and phosphorylated p38 expression). In contrast, hADSCs cultured with small and non-uniform porous scaffolds showed significantly increased apoptotic activity with decreased chondrogenic differentiation. Taken together, inverse opal scaffold could potentially be used as an effective tool for improving chondrogenesis using stem cells.

How Much Do We Understand About Use of E-Commerce in OPAL Generation?: Focused on Diffusion of Innovation Theory (우리는 오팔(OPAL)세대의 이커머스 이용을 얼마나 이해하고 있는가?: 혁신확산이론을 중심으로)

  • Kim, Yesolran;Kim, Tae-Eun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.22 no.5
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    • pp.129-137
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    • 2022
  • This study compared the sociodemographic characteristics and innovativeness of OPAL generation e-commerce users and non-users based on the innovation diffusion theory, and examined the effect of these personal characteristics on the availability of e-commerce use. The result showed that OPAL generation e-commerce users differed from non-users in gender, age, income level, education level, and functional, hedonistic, social and cognitive innovativeness. In addition, gender, age, educational level, functional and hedonistic innovativeness were found to be significant variables that determined the OPAL generation's use of e-commerce. Based on these results, we presented the theoretical and practical implications of this study.