• Title/Summary/Keyword: Chemical coupling

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Solution-processible corrugated structure and scattering layer for enhanced light extraction from organic light-emitting diodes

  • Hyun, Woo Jin;Im, Sang Hyuk;Park, O Ok;Chin, Byung Doo
    • Journal of Information Display
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    • v.13 no.4
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    • pp.151-157
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    • 2012
  • A simple method of fabricating out-coupling structures was demonstrated via solution-processing to enhance light extraction from organic light-emitting diodes (OLEDs). Scattering layers were easily obtained by spin-coating an $SiO_2$ sol solution that contained $TiO_2$ particles. By introducing the scattering layer and the solution-processible corrugated structure as internal and external extraction layers, the OLEDs showed increased external quantum efficiency without a change in the electroluminescence spectrum compared to conventional devices. Using these solution-processible out-coupling structures, nearly all-solution-processed OLEDs with enhanced light extraction could be fabricated. The light extraction enhancement is attributed to the suppression by the out-coupling structures of the light-trapping that arose at the interface of the glass substrate and the air.

Theory of the Chemical Bond. Bond Ionicities and Bond Energies of Diatomic Molecules

  • Kang, Young-Kee
    • Bulletin of the Korean Chemical Society
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    • v.6 no.2
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    • pp.107-111
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    • 1985
  • A revised simple method is proposed to calculated the ionicities and bond energies of diatomic molecules including hydrogen halides, interhalogen compounds, alkali hydrides, and alkali halides. The relative nuclear quadrupole coupling constants are evaluated to check the further validity of this method. It is shown that calculated values are consistent with available experimental values.

Direct Palladium-Catalyzed C-4 Arylation of Tri-substituted Furans with Aryl Chlorides: An Efficient Access to Heteroaromatics

  • Yang, Hai;Zheng, Zhishuo;Zeng, Jian;Liu, Huajie;Yi, Bing
    • Bulletin of the Korean Chemical Society
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    • v.33 no.8
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    • pp.2623-2626
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    • 2012
  • A series of functionalized furans were synthesized by way of a palladium-catalyzed coupling reaction of 2,3,5-trisubstituted furans with aryl chlorides through C-H bond cleavages at C-4 position. The feature of the reaction was facilitative preparation of furan derivatives with good functional group tolerance. All reactions gave the desired products in moderate to good yields in the presences of $BuAd_2P$ and t-BuOK in DMF at $120^{\circ}C$ after 15 h.

Preparation and Characterization of PEG/PLA Multiblock and Triblock Copolymer

  • Zhao, Hesong;Liu, Zhun;Park, Sang-Hyuk;Kim, Sang-Ho;Kim, Jung-Hyun;Piao, Longhai
    • Bulletin of the Korean Chemical Society
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    • v.33 no.5
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    • pp.1638-1642
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    • 2012
  • A series of poly (lactic acid) (PLA) and poly (ethylene glycol) (PEG) tri and multiblock copolymers with relatively high molecular weights were synthesized through the coupling reaction between the bis(acyl chloride) of carboxylated PLA and mono or dihydroxy PEG. The coupling reaction and the copolymer structures were monitored by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The melting temperature (Tm) of PEG blocks decreased with the presence of PLA sequences attaching to PEG blocks. The CMC values were determined to be 10-145 mg/L depending on the length of PLA and PEG blocks and the structure of the block copolymers.

Studies on the Nuclear Magnetic Resonance Spectra of (E)-1-Aryl-3-(2- and 3-thienyl)-2-propenones and Unique Observation of 4J and 5J Coupling in Their 1H-1H COSY

  • HanLee, In-Sook;Jeon, Hyun-Ju;Lee, Chang-Kiu
    • Bulletin of the Korean Chemical Society
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    • v.32 no.2
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    • pp.687-692
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    • 2011
  • $^1H$ and $^{13}C$ NMR spectra of series of (E)-1-aryl-(2- and 3-thienyl)-2-propenones, that are aldol condensation products between 2- and 3-thiophenecarbaldehydes and m- and p-substituted acetophenones, were examined to make complete assignments of the chemical shifts. Long range couplings, $^4J$ and $^5J$, are observed in the $^1H-^1H$ COSY of both 2- and 3-thienyl compounds, which makes the elucidation of the conformation in solution possible. In contrast, the 2-furyl analogue shows the long range coupling phenomena, but the 3-furyl and phenyl analogues do not show similar phenomena.

Super Coupling Dual-gate Ion-Sensitive Field-Effect Transistors

  • Jang, Hyun-June;Cho, Won-Ju
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.239-239
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    • 2013
  • For more than four decades, ion-sensitive field-effect transistor (ISFET) sensors that respond to the change of surface potential on a membrane have been intensively investigated in the chemical, environmental, and biological spheres, because of their potential, in particular their compatibility with CMOS manufacturing technology. Here, we demonstrate a new type of ISFET with dual-gate (DG) structure fabricated on ultra-thin body (UTB), which highly boosts sensitivity, as well as enhancing chemical stability. The classic ion-sensitive field-effect transistor (ISFET) has been confronted with chronic problems; the Nernstian response, and detection limit with in the Debye length. The super-coupling effects imposed on the ultra thin film serve to not only maximize sensitivity of the DG ISFET, but also to strongly suppress its leakage currents, leading to a better chemical stability. This geometry will allow the ISFET based biosensor platform to continue enhancement into the next decade.

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Influence of Carbon Fiber on Corrosion Behavior of Carbon Steel in Simulated Concrete Pore Solutions

  • Tang, Yuming;Dun, Yuchao;Zhang, Guodong;Zhao, Xuhui;Zuo, Yu
    • Corrosion Science and Technology
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    • v.16 no.4
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    • pp.175-182
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    • 2017
  • Galvanic current measurement, polarization curves, electrochemical impedance spectroscopy and weight loss test were used to study the corrosion behavior of carbon steel before and after carbon fibers coupling to the carbon steel in simulated concrete pore solutions, and the film composition on the steel surface was analyzed using XPS method. The results indicate that passive film on steel surface had excellent protective property in pore solutions with different pH values (13.3, 12.5 and 11.6). After coupling with carbon fibers (the area ratio of carbon steel to carbon fiber was 12.31), charge transfer resistance $R_{ct}$ of the steel surface decreased and the $Fe^{3+}/Fe^{2+}$ value in passive film decreased. As a result, stability of the film decreased and the corrosion rate of steel increased. Decreasing of the area ratio of steel to carbon fiber from 12.3 to 6.15 resulted in the decrease in $R_{ct}$ and the increase in corrosion rate. Especially in the pore solution with pH 11.6, the coupling leads the carbon steel to corrode easily.

Advanced Synthetic Technology for High Performance Energy Tire Tread Rubber (고성능 에너지 절약형 타이어 트레드 고무의 합성 제조 기술)

  • Lee, Bum-Jae;Lim, Ki-Won;Ji, Sang-Chul;Jung, Kwon-Young;Kim, Tae-Jung
    • Elastomers and Composites
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    • v.44 no.3
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    • pp.232-243
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    • 2009
  • The specialized and diversified synthetic and compounding technologies are used to meet the requirements for the advanced high performance tire tread materials with better balance of fuel economy(rolling resistance), safety(wet traction) and wear resistance. These techniques involve the methodology for the improvement of chemical and physical interaction between filler and the rubber matrix using coupling agents as well as a variety of chemically-modified solution SBRs. The research trends about the high performance functional SBRs and coupling agents which can interact with the surface of fillers and their working mechanism were investigated in the conventional carbon black-filled rubber and silica-filled SBR systems developed recently as "green tire".