• 제목/요약/키워드: material synthesis

검색결과 1,770건 처리시간 0.03초

Asymmetric Ring Opening of Epoxides Catalyzed by Novel Heterobimetallic Schiff-Bases Containing Transition Metal Salts

  • Kawthekar, RahulB;Bi, Wentao;Kim, Geon-Joong
    • Bulletin of the Korean Chemical Society
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    • 제29권2호
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    • pp.313-318
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    • 2008
  • An enantioselective ring opening of racemic terminal epoxides has been achieved by using heterobimetallic cobalt salen complexes with variety of nucleophiles. They were proven to be highly enantioselective and reactive for the synthesis of valuable chiral building blocks in enantio-riched forms up to 98% ee.

Investigation on the Effectiveness of Aqueous Carbonated Lime in Producing an Alternative Cementitious Material

  • Jo, Byung-Wan;Chakraborty, Sumit;Choi, Ji Sun;Jo, Jun Ho
    • International Journal of Concrete Structures and Materials
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    • 제10권1호
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    • pp.15-28
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    • 2016
  • With the aim to reduce the atmospheric $CO_2$, utilization of the carbonated lime produced from the aqueous carbonation reaction for the synthesis of a cementitious material would be a promising approach. The present investigation deals with the aqueous carbonation of slaked lime, followed by hydrothermal synthesis of a cementitious material utilizing the carbonated lime, silica fume, and hydrated alumina. In this study, the aqueous carbonation reaction was performed under four different conditions. The TGA, FESEM, and XRD analysis of the carbonated product obtained from the four different reaction conditions was performed to evaluate the efficacy of the reaction conditions used for the production of the carbonated lime. Additionally, the performance of the cementitious material was verified analyzing the physical characteristics, mechanical property and setting time. Based on the results, it is demonstrated that the material produced by the hydrothermal method possesses the cementing ability. Additionally, it is revealed that the mortar prepared using the alternative cementitious material yields $33.8{\pm}1.3MPa$ compressive strength. Finally, a plausible reaction scheme has been proposed to explain the overall performances of the aqueous carbonation as well as the hydrothermal synthesis of the cementitious material.

Synthesis, properties and applications of Halogen containing polyimides

  • Kravtsova, V.D.;Zhubanov, B.A.
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2000년도 하계학술대회 논문집
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    • pp.255-258
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    • 2000
  • The new approach for synthesis of novel condensation monomers and polyimides on the basis of them was developed. The correlation between synthesis regularities, structure and properties of monomers and polyimides was studied. The areas of industrial application of synthesized polymer were determined.

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S-L-S 성장기구를 이용한 양질의 골드 나노선 합성 (Synthesis of Au Nanowires Using S-L-S Mechanism)

  • 노임준;김성현;신백균;조진우
    • 한국전기전자재료학회논문지
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    • 제25권11호
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    • pp.922-925
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    • 2012
  • Single crystalline Au nanowires were successfully synthesized in a tube-type furnace. The Au nanowires were grown by vapor phase synthesis technique using solid-liquid-solid (SLS) mechanism on substrates of corning glass and Si wafer. Prior to Au nanowire synthesis, Au thin film served as both catalyst and source for Au nanowire was prepared by sputtering process. Average length of the grown Au nanowires was approximately 1 ${\mu}m$ on both the corning glass and Si wafer substrates, while the diameter and the density of which were dependent on the thickness of the Au thin film. To induce a super-saturated states for the Au particle catalyst and Au molecules during the Au nanowire synthesis, thickness of the Au catalyst thin film was fixed to 10 nm or 20 nm. Additionally, synthesis of the Au nanowires was carried out without introducing carrier gas in the tube furnace, and synthesis temperature was varied to investigate the temperature effect on the resulting Au nanowire characteristics.

GNP법에 의한 $(La_{1-x}Sr_x)MnO_{3+\delta}$ 분말의 환원특성 (Reduction Properties of $(La_{1-x}Sr_x)MnO_{3+\delta}$ Powder by GNP)

  • 이미재;백종후;김세기;박상선;최병현;이경희
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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    • pp.242-243
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    • 2005
  • In this study, (La,Sr)$MnO_{3+\delta}$ powder used cathode material for SOFC was synthesized with precursor by GNP and the properties of powder, crystal phase, electric properties and deoxidization properties with precursor were investigated. The synthesis powder was prepared when oxidant/fuel mole and pH were 1 and 1, respectively and the synthesis powder was synthesized by GNP method using nitrate solution or oxide solution as precursor. Deoxidization peak of the nitrate solution was appeared lower temperature than the oxide solution, at $450^{\circ}C$. In this result, synthesis (La,Sr)$MnO_{3+\delta}$ powder using nitrate solution with Mn excess was suitable cathode material for SOFC due to had higher deoxidization properties. Also synthesis (La,Sr)$MnO_{3+\delta}$ powder according to precursor had difference electrical conductivity according to influence sintering density and crystal phase with precursor. Specially, the synthesis method and starting material had effect on deoxidization properties for SOFC.

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The rapid synthesis of $MoSi_2$ for high-temperature furnace heating elements

  • Soh, Dea-Wha;Natalya, Korobova
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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    • pp.38-41
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    • 2001
  • The combustion characteristics of the disilicides molybdenum system have been studied experimentally. The pertinent reaction parameters that control self-propagating high temperature synthesis reactions have been examined. These include reactant particle size, powder mixing and compaction, reaction stoichiometry, diluents. The influence of experimental variables on integrity, uniformity, structure, and related material properties will be discussed. Formation mechanism of $MoSi_2$ during SHS might be different and depending on experimental conditions.

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