• 제목/요약/키워드: complex oxide

검색결과 397건 처리시간 0.026초

Development of Fe-12%Cr Mechanical-Alloyed Nano-Sized ODS Heat-Resistant Ferritic Alloys

  • 김익수;최병영
    • 소성∙가공
    • /
    • 제8권3호
    • /
    • pp.265-265
    • /
    • 1999
  • The development of mechanical alloying (MA)-oxide dispersion strengthened (ODS) heat-resistant ferritic alloys of Fe-12%Cr with W, Ti and Y₂O₃additions were carried out. Fe-12%Cr alloys with 3%W, 0.4%Ti and 0.25% Y₂O₃additions showed a much finer and more uniform dispersion of oxide particles among the alloy system studied. Nano-sized oxides dispersed in the alloys suppress the grain growth during annealing at a high temperature and resulted in the remarkable improvement of creep strength. The oxide phase was identified as a complex oxide type of Y-Ti-O.

고분해능 투과전자현미경 연구에 의한 ${\gamma}$-Al2O3의 상 전산모사 (Compouter Image Simulation of ${\gamma}$-Al2O3 in High-Resolution Transimission Electron Microscopy)

  • 이정용
    • 한국세라믹학회지
    • /
    • 제26권2호
    • /
    • pp.276-288
    • /
    • 1989
  • Interpretation of high-resolution transmission electron microscopy images of defects and complex structures such as found in ceramics generally requires matching of the images with compound image simulations for reliable interpretation. A transmission electron microscopy study of the aluminum oxide was carried out at high-resolution, so that the crystal structure of the aluminum oxide could be modelled on an atomic level. In conjunction with computer simulation comparisons, the images reveal directly the atomic structure of the oxide. Results show that comparison between experimental high-resolution electron microscopy images and simulated images leads to a one to one correspondence of the image to the atomic model of the aluminum oxide. The aluminum atoms are disordered in the octahedral sites and the tetrahedral sites in the spinel aluminum oxide.

  • PDF

주조 오스테나이트 스테인리스강 상경계 균열부 산화물 분석 (Analysis of Oxide Layers in Phase Boundary Crack of Cast Austenitic Stainless Steel)

  • 최민재;김성우
    • 한국압력기기공학회 논문집
    • /
    • 제19권2호
    • /
    • pp.171-178
    • /
    • 2023
  • For the phase boundary crack found in the gasket made of cast austenitic stainless steel in the nuclear power plant, the oxide layers were analyzed through SEM and TEM. The results showed that cracks initiated and propagated along the austenite/δ-ferrite phase boundary, the propagation path was changed to penetrate the inside of the phase. The oxide layer located at the periphery of the crack along the phase boundary was identified as a complex multi-layered spinel structure, and Cr-rich carbides were also detected in the oxide. The cracks that propagated inside the austenite matrix were attributed to the presence of high external stresses and impurities.

Catalytic Hydrolysis of Phosphate Diesters as DNA Model with Tetranuclear Nickle (II) Complex

  • Sung, Nack-Do;Kim, Tae-Young
    • Journal of Applied Biological Chemistry
    • /
    • 제49권3호
    • /
    • pp.86-89
    • /
    • 2006
  • The novel tetranuclear nickel (II) complex is a high rate accelerator in promoting hydrolysis of phosphate diesters. Nickel-bound bis-nitrophenyl phosphate (BNPP) can be $10^4$ times more reactive than the unbound BNPP. The large rate of enhancements by the complex slightly under basic condition has shown high catalytic activity in phosphate diester cleavage. The bell-shaped pH-rate profile indicated that the nickel-oxide form of the tetranuclear complex or its kinetic equivalent was the active species for cleaving BNPP. The catalytic hydrolysis between tetranuclear nickel (II) complex and phosphate diester proceeds via the formation of bidentate coordination of the anionic phosphate to the Ni (II) atom. This reveals that the complex has the possibility as artificial nuclease.

햄프(Cannabis sativa L.)씨드오일 복합물의 항염증 효과에 관한 연구 (Study on the anti-inflammatory effects of Cannabis sativa L. seed oil complex)

  • 김채현;김세기;장영아;권용진
    • 한국응용과학기술학회지
    • /
    • 제41권2호
    • /
    • pp.251-259
    • /
    • 2024
  • 본 연구는 햄프씨드오일 (Cannabis sativa L. seed oil, CSO)와 햄프씨드오일 복합물 (Cannabis sativa L. seed oil complex, CSOC)의 비교분석을 통해 항염증 소재로서의 가능성을 평가하였다. CSO와 CSOC의 항염증 효과는 lipopolysaccharide (LPS)-induced RAW264.7 모델을 통해 확인하였다. Lipoxygenase inhibition activity를 통해 지질산화억제를 확인한 결과, CSO는 억제되지 않았지만 COSC는 70% 이상 억제되었다. MTT assay를 통해 세포독성을 확인해본 결과, CSO는 세포독성을 보이지 않았지만 CSOC는 200 ㎍/ml 이상 농도에서 세포독성을 보였다. LPS로 유도된 RAW264.7에서 inducible nitric oxide synthase (iNOS)의 발현과 nitric oxide (NO)의 생산은 CSOC가 CSO보다 현저하게 억제하였다. 또한, cyclooxygenas (COX)-2의 발현과 prostraglandin E2 (PGE2)의 생성을 확인해본 결과에서도 CSOC가 CSO보다 현저하게 억제하였다. 본 연구를 통해, CSOC가 CSO보다 우수한 항염증 효과를 가지며, 항염증 소재로 활용 가능성이 있음을 확인했다.

Anti-inflammatory Activity of Complex Saponin Separated from Pueraria flos and Adzuki Beans Mixture Extract

  • Jung Hwan Nam;Jong Nam Lee;Su hyoung Park;Su Jeong Kim;Hwang Bae Sohn;Do Yeon Kim
    • 한국자원식물학회:학술대회논문집
    • /
    • 한국자원식물학회 2022년도 추계학술대회
    • /
    • pp.90-90
    • /
    • 2022
  • Pueraria flos and Adzuki Beans contains several bioactive compounds, such as saponin, oleanolic acid, and flavone. Pueraria flos and Adzuki Beans has traditionally been used to treat disorders of antioxidant activity, diabetes and liver detoxication, and it has antinociceptive and anti-inflammatory properties. However, complex saponin were validity of the anti-inflammatory activity has not been scientifically investigated. In this study, to determine anti-inflammatory activity of complex saponin separated from Pueraria flos and Adzuki Beans mixture extract on nitric oxide and prostaglandinE2 assay. The anti-inflammatory activities of complex saponin separated from Pueraria flos and Adzuki Beans mixture extract were evaluated for inhibitory activities against lipopolysacchride induced nitric oxide and prostaglandinE2 production protein expressions in RAW264.7 cell lines. The complex saponin separated from Pueraria flos and Adzuki Beans mixture extract inhibitory activity for both tests with protein high depressions(%) values showed in the ranges of 50~100 ㎍/ml. Overall, prostaglandinE2 tests had a higher inhibitory effect on inflammation than nitricoxide tests. Theseis result suggest a potential role of complex saponin separated from Pueraria flos and Adzuki Beans mixture extract as source of anti-inflammation agent.

  • PDF

초전도 $MgB_2$ 박막의 온도와 장기장의 변화에 따른 광학적 성질 (Temperature and magnetic field dependent optical properties of superconducting $MgB_2$ thin film)

  • 정종훈;이해자;김경완;김명훈;노태원;;강원남;정창욱;이성익
    • Progress in Superconductivity
    • /
    • 제3권1호
    • /
    • pp.31-35
    • /
    • 2001
  • We investigated the temperature and magnetic field dependent optical properties of a$ MgB_2$ thin film in the far-infrared region. In the superconducting state, i.e. 5 K, we obtained the values of superconducting gap $2\Delta$ ~ 5.2 meV and $2\Delta$ $_{k}$ $B/T_{c}$ ~1.8. Although the value of$ 2\Delta$$B/T_{c}$ was nearly half of the BCS value, the $2\Delta$ seemed to follow the temperature dependence of the BCS formula. Under the magnetic field (H), the superconducting state became suppressed. Interestingly, we found that the normal state area fraction abruptly increased at low field but slowly increased at high field. It did not follow the H-dependences predicted for a s-wave superconductor (i.e. a linear dependence) nor for a s-wave one (i.e. $H^{1}$2/ dependence). We discussed the complex gap nature of $MgB_2$ in comparison with two gap and anisotropic s-wave scenarios.ios.

  • PDF

TiO2에 담지된 금속 산화물 촉매상에서 TCE 산화분해반응 (Oxidative Decomposition of TCE over TiO2-Supported Metal Oxide Catalysts)

  • 양원호;김문현
    • 한국환경과학회지
    • /
    • 제15권3호
    • /
    • pp.221-227
    • /
    • 2006
  • Oxidative TCE decomposition over $TiO_2$-supported single and complex metal oxide catalysts has been conducted using a continuous flow type fixed-bed reactor system. Different types of commercial $TiO_2$ were used for obtaining the supported catalysts via an incipient wetness technique. Among a variety of titanias and metal oxides used, a DT51D $TiO_2\;and\;CrO_x$ would be the respective promising support and active ingredient for the oxidative TCE decomposition. The $TiO_2-based\;CrO_x$ catalyst gave a significant dependence of the catalytic activity in TCE oxidation reaction on the metal loadings. The use of high $CrO_x$ contents for preparing $CrO_x/TiO_2$ catalysts might produce $Cr_2O_3$ crystallites on the surface of $TiO_2$, thereby decreasing catalytic performance in the oxidative decomposition at low reaction temperatures. Supported $CrO_x$-based bimetallic oxide systems offered a very useful approach to lower the $CrO_x$ amounts without any loss in their catalytic activity for the catalytic TCE oxidation and to minimize the formation of Cl-containing organic products in the course of the catalytic reaction.

EBSD Microstructural Characterisation of Oxide Scale on Low Carbon Steel

  • Birosca, S.;De Cooman, B.C.
    • Corrosion Science and Technology
    • /
    • 제7권3호
    • /
    • pp.182-186
    • /
    • 2008
  • The microstructures of the oxide scale developed at high temperature on steels are very complex and their development depends on many factors including time, temperature, oxidation conditions and alloying elements. The classical model of an oxide scale on steel consisting of wüstite, magnetite and haematite layers, is more complicated in reality and its properties change with the factors that affect their development. An understanding of the oxide scale formation and its properties can only be achieved by careful examination of the scale microstructure. The oxide scale microstructure may be difficult to characterise by conventional techniques such as optical or standard scanning electron microscopy. An unambiguous characterisation of the scale and the correct identification of the phases within the scale are difficult unless the crystallographic structure for each phase in the scale is considered and a simultaneous microstructure-microtexture analysis is carried out. In the current study Electron Backscatter Diffraction (EBSD) has been used to investigate the microstructure of iron oxide layers grown on low carbon steels at different times and temperatures. EBSD has proved to be a powerful technique for identifying the individual phases in the oxide scale accurately. The results show that different grain shapes and sizes develop for each phase in the scale depending on time and temperature.