• Title/Summary/Keyword: %CE%B2A

Search Result 148, Processing Time 0.023 seconds

Epitaxial growth of silicon thin films on insulating ($CeO_2$/Si) substrates (절연체 ($CeO_2$/Si)위에 성장된 실리콘 박막의 특성 연구)

  • 양지훈;문병식;김관표;김종걸;정동근;노용한;박종윤
    • Journal of the Korean Vacuum Society
    • /
    • v.8 no.3B
    • /
    • pp.322-326
    • /
    • 1999
  • We have investigated the growing process of a silicon film on the $CeO_2/Si$ surface. The silicon was deposited by using electron beam deposition method. The $CeO_2$(111) film was grown on a (111)-oriented silicon substrate at $700^{\circ}C$ at oxygen [partial pressure of $5\times10^{-5}$ Torr. To investigate the condition of epitaxial growth of si films on the $CeO_2/Si$ substrate, we deposited Si at various temperature니 The overlayer silicon was characterized by using x-ray diffraction(XRD). double crystal x-ray diffraction (DCXRD), and transmission electron microscopy (TEM). At temperature higher than $690^{\circ}C$, $CeO_2$ layer was observed at the $CeO_2/Si$ interface, which was formed by chemical reaction with silicon and oxygen dissociated from $CeO_2$. When silicon was deposited on the $CeO_2/Si$ at $620^{\circ}C$, silicon grew epitaxially along the (111)-direction.

  • PDF

Effects of Tumeric (Curcuma aromatica Salab.) Extract on Shelf Life of Cooked Rice (강황 추출물이 쌀밥의 저장성에 미치는 영향)

  • Lim, Yong-Suk;Park, Kyoung-Nam;Lee, Shin-Ho
    • Food Science and Preservation
    • /
    • v.14 no.5
    • /
    • pp.445-450
    • /
    • 2007
  • This studies were engaged to investigate the potential us of Curcuma aromatica Salab. as a food ingredients. The antimicrobial activity of Curcuma aromatica Salab. extract (CE) and effect on shelf life of the cooked rice were examined. The antimicrobial activity of CE showed apparently against Bacillus cereus, B. subtilis and B. megaterium. The minimum inhibitory concentration (MIC) of CE was 0.15% for B. cereus md 0.2% for B. subtilis and B. megaterium. The antimicrobial activity of CE remained relatively high after heat treatments(30 min at 80 and $100^{\circ}C$, 15 min at $121^{\circ}C$). The shelf life of cooked rice containing above 0.05% CE increased more 1 or 2 days than that of control at $30^{\circ}C$, The texture of cooked rice was improved by addition of above 0.01% CE. The sensory quality of cooked rice with CE did not show significant difference between 0.00% and 0.05% in taste and overall acceptability but decreased above 0.10% in taste, color, flavor and overall acceptability.

Physicochemical and Functional Characterization of Blue-Shelled Eggs in Korea

  • Sujiwo, Joko;Kim, Dongwook;Yoon, Ji-Yeol;Kim, Hanna;Kim, Jung-Soo;Lee, Sung-Ki;Jang, Aera
    • Food Science of Animal Resources
    • /
    • v.37 no.2
    • /
    • pp.181-190
    • /
    • 2017
  • The aim of this study was to compare the quality and physicochemical characteristics of blue-shelled eggs (BE) and conventional eggs (CE). Proximate composition, quality, pH value, shell color, collagen content, fatty acid composition, total cholesterol, ${\alpha}$-glucosidase inhibition activity, and antioxidation activity were determined. The proximate composition, general qualities, and pH values of CE and BE showed no significant differences, except in moisture composition, weight, and shell thickness. Moisture content and weight of BE were significantly lower than those of CE. However, shell thickness and weight of BE were higher than those of CE (p<0.05). Lightness of BE was significantly higher than that of CE (85.20 vs. 58.80), while redness ($a^*$) and yellowness ($b^*$) of BE were lower than those of CE ($a^*$: -4.75 vs. 14.20; $b*$: 10.45 vs. 30.63). The fatty acid [C18:1n7 (cis-vaccenic acid) and C18:3n6 (gamma-linolenic acid)] contents of BE were significantly higher than those of CE. The total cholesterol contents of BE and CE were similar. DPPH radical scavenging activity of BE was significantly higher than that of CE (40.78 vs. 35.35). Interestingly, ${\alpha}$-glucosidase inhibition activity of whole egg and egg yolk in BE (19.27 and 36.06) was significantly higher than that of whole egg and egg yolk in CE (13.95 and 32.46). This result indicated that BE could potentially be used as a functional food material. Further studies are required to evaluate the specific compounds that affect functional activity.

Multichannel Photoreceiver Arrays for Parallel Optical Interconnects (병렬식 광 인터컨넥트용 멀티채널 수신기 어레이)

  • Park, Sung-Min
    • Journal of the Institute of Electronics Engineers of Korea SD
    • /
    • v.42 no.7 s.337
    • /
    • pp.1-4
    • /
    • 2005
  • A four-channel photoreceiver ways have been realized in a 0.8$\mu$m Si/SiGe HBT technology for the applications of parallel optical interconnects. The receiver array includes four-channel transimpedance amplifiers (TIAs) and p-i-n photodiodes, where the TIAs exploit a common-emitter (CE) input configuration. Measured results demonstrate that the four-channel CE TIA array provides 3.9GHz bandwidth, 62dB$\Omega$ transimpedance gain, 7.5pA/sqrt(Hz) average noise current spectral density, and less than -25dB crosstalk between adjacent channels with 40mW power dissipation.

Antifungal Activity of an Endophytic Fungus Aspergillus versicolor DYSJ3 from Aphanamixis grandifolia Blume against Colletotrichum musae

  • Li, Xiaoyu;Wu, Yateng;Liu, Zhiqiang
    • Mycobiology
    • /
    • v.49 no.5
    • /
    • pp.498-506
    • /
    • 2021
  • An endophytic fungus strain DYSJ3 was isolated from a stem of Aphanamixis grandifolia Blume, which was identified as Aspergillus versicolor based on the morphological characteristics, internal transcribed spacer (ITS) and calmodulin gene sequences analyses. A. versicolor DYSJ3 exhibited strong antagonistic activity against Colletotrichum musae, C. gloeosporioides and Fusarium oxysporum f. sp. cubense with the inhibition rates of 61.9, 51.2 and 55.3% respectively. The antifungal metabolites mainly existed in the mycelium of A. versicolor DYSJ3, and its mycelial crude extract (CE) had broad-spectrum antifungal activities against plant pathogenic fungi. The CE had a good thermal stability, and the inhibition rate of 100 mg/mL CE against C. musae was above 70.0% after disposing at 120 ℃ for 1 h. Five secondary metabolites were isolated from the CE and identified as averufanin, ergosterol peroxide, versicolorin B, averythrin and sterigmatocystin. Activity evaluation showed versicolorin B exhibited inhibitory effects on the mycelial growth and conidial germination of C. musae, and sterigmatocystin had a weak inhibitory effect on the mycelial growth of C. musae.

A study on the magnetic properties of (Ce-Didymium)-Fe-B alloy ((Ce-Didymium)-Fe-B 합금의 자기적 성질에 관한 연구)

  • 김종오;노재승
    • Electrical & Electronic Materials
    • /
    • v.3 no.1
    • /
    • pp.36-44
    • /
    • 1990
  • 본 연구는 34wt%(5Ce-Didymium)-Fe-1wt%B 합금의 분말입도, 성형압력 및 소결온도 에 따른 자기적 성질에 관하여 연구하였다. 그리고 각각의 자기적 성질에 영향을 주는 인자를 알아내기 위하여 밀도측정, 미세조직 및 자구를 관찰하였다. 미세조직은 금속현미경을 이용하여 관찰하였으며 자구는 Bitter법으로 관찰하였다. 결과는 아래와 같다. (1)분말의 입도와 결정립 크기가 작아질수록 경질자기 특성은 증가하였으며 소결온도가 증가할수록 경질자기 특성도 증가하였다. 그러자 압력은 1000kg/$cm^{2}$일때 가장 좋은 경질자기 특성이 얻어졌다. (2)결정립이 클수록 자구의 구조는 복잡했으며 미세한 결정립일수록 큰 결정립에 비해 큰 보자력을 갖는다. 포화된 후에는 거의 모든 결정립이 단자구였으며 열적으로 탈자되었을 경우에는 모두가 multi-domain였다. (3)가장 우수한 경질자기 특성은 3-5.mu.m의 분말을 사용하여 1080.deg.C에서 소결한 후 590.deg.C에서 열처리한 시편에서 얻어졌으며 (BH)$_{max}$는 214.6kJ.m$_{-3}$이다.

  • PDF

Synthesis of Nano Size $BaCeO_3$ as an Effective Flux Pining Center for YBCO Superconductor (YBCO 초전도체의 효과적인 플럭스 피닝 센터로서의 나노 크기 $BaCeO_3$ 합성)

  • Youn, J.S.;No, K.S.;Kim, Y.H.;Jun, B.H.;Lee, J.P.;Jung, S.Y.;Kim, C.J.
    • Progress in Superconductivity
    • /
    • v.10 no.1
    • /
    • pp.12-16
    • /
    • 2008
  • In this work, nano size $BaCeO_3$, which is a possible flux pinning medium of melt processed $YBa_{2}Cu_{3}O_x$ superconductor, was synthesized by the conventional solid state reaction method using powders. $BaCeO_3$ and $CeO_2$ were mixed thoroughly using a ball milling for 24 hours and calcined at $1200^{\circ}C$ for 5 hours for the formation $BaCeO_3$ powder. The obtained $BaCeO_3$ powder was attrition milled at various milling times of 60 min, 120 min and 240 min. The $BaCeO_3$ powders of various milling times were mixed with $YBa_{2}Cu_{3}O_x$ powder. Seed melt processed $YBa_{2}Cu_{3}O_x$-$BaCeO_3$ (15wt.%) superconductors were prepared and the superconducting properties were investigated. It was found that $T_c$ of $Y_{1.5}Ba_{2}Cu_{3}O_x$ samples was not significantly affected by $BaCeO_3$ addition, but $J_c$ of samples was increased by $BaCeO_3$ addition. The $J_c$ improvement by fine $BaCeO_3$ powder (120 min attrition-milled) was effective at low magnetic fields less than 2 T.

  • PDF

Theoretical Investigation of Water Adsorption Chemistry of CeO2(111) Surfaces by Density Functional Theory (전자밀도함수이론을 이용한 세륨 산화물의 (111) 표면에서 일어나는 물 흡착 과정 분석)

  • Choi, Hyuk;Kang, Eunji;Kim, Hyun You
    • Korean Journal of Materials Research
    • /
    • v.30 no.5
    • /
    • pp.267-271
    • /
    • 2020
  • Cerium oxide (ceria, CeO2) is one of the most wide-spread oxide supporting materials for the precious metal nanoparticle class of heterogeneous catalysts. Because ceria can store and release oxygen ions, it is an essential catalytic component for various oxidation reactions such as CO oxidation (2CO + O2 2CO2). Moreover, reduced ceria is known to be reactive for water activation, which is a critical step for activation of water-gas shift reaction (CO + H2O → H2 + CO2). Here, we apply van der Waals-corrected density functional theory (DFT) calculations combined with U correction to study the mechanism of water chemisorption on CeO2(111) surfaces. A stoichiometric CeO2(111) and a defected CeO2(111) surface showed different water adsorption chemistry, suggesting that defected CeO2 surfaces with oxygen vacancies are responsible for water binding and activation. An appropriate level of water-ceria chemisorption energy is deduced by vdW-corrected non-local correlation coupled with the optB86b exchange functional, whereas the conventional PBE functional describes weaker water-ceria interactions, which are insufficient to stabilize (chemisorb) water on the ceria surfaces.

Superconducting Properties of (Sm/Y)-Ba-Cu-0 High Tc Composite Superconductors with CeO2 Additive by Zone-Melt Textured Growth (국부용융성장법으로 제조한 (Sm/Y)-Ba-Cu-0계 고온복합초전도체의 CeO2첨가에 따른 초전도특성)

  • 김소정
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.15 no.3
    • /
    • pp.269-274
    • /
    • 2002
  • (Sm/Y)-Ba-Cu-O system high Tc composite superconductors with/without $CeO_2$ additive were directionally grown by zone-melting process, haying large temperature gradient, In air atmosphere. Cylindrical green rods of $({Sm/y})_{1.8}Ba_{2.4}Cu_{3.4}O_x$ [(Sm/Y)1.8] composite oxides by cold isostatic pressing(CIP) method using rubber mold were fabricated. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The size of nonsuperconducting $({Sm/y})_2BaCuO_5$ inclusions of the melt-textured (Sm/Y)1.8 sample with CeO$_2$ additive were remarkably reduced and uniformly distributed within the superconducting (Sm/Y)1.8 matrix. Both samples, with/without $CeO_2$ additive, showed an onset Tc $\geq$ 90 K and sharp superconducting transition. The critical current density Jc value of the $CeO_2$ addictive were $1{\times}10^5A/\textrm{cm}^2$ in 77 K, 0 Tesla.

SCC Inhibitors for SG Tube Materials in Nuclear Power Plants

  • Kim, Kyung-Mo;Lee, Eun-Hee;Kim, Uh-Chul
    • Proceedings of the Korean Powder Metallurgy Institute Conference
    • /
    • 2006.09a
    • /
    • pp.585-586
    • /
    • 2006
  • Several chemicals were studied to suppress the damage due to stress corrosion cracking (SCC) of steam generator (SG) tubes in nuclear power plants. The effects on the SCC of the compounds, $TiO_2$, TyzorLA and $CeB_6$, were tested for several types of SG tubing materials. The test with the addition of $TiO_2$ and $CeB_6$ showed an effect in decreasing the SCC for the SG tubing material. However, $CeB_6$ caused some more SCC for Alloy 800. The penetration property into a crevice of the inhibitors was investigated by using Alloy 600 specimens with different gap.

  • PDF