• 제목/요약/키워드: High-$T_{c}$

검색결과 4,287건 처리시간 0.037초

Liquid-Phase Sintered SiC Ceramics with Oxynitride Additives

  • Rixecker, G.;Biswas, K.;Wiedmann, I.;Sldinger, F.
    • 한국결정성장학회:학술대회논문집
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    • 한국결정성장학회 2000년도 Proceedings of 2000 International Nano Crystals/Ceramics Forum and International Symposium on Intermaterials
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    • pp.1-33
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    • 2000
  • Silicon carbide ceramics with sintering additives from the system AlN-Y$_2$O$_3$ can be gas-pressure sintered to theoretical density. While commonly a combination of sesquioxides is used such as Al$_2$O$_3$-Y$_2$O$_3$, the oxynitrid additives offer the advantage that only a nitrogen atmosphere is require instead of a powder. By starting form a mixture of ${\beta}$-SiC and ${\alpha}$-SiC, and by performing dedicated heat treatments after densification, anisotropic grain growth is obtained which leads to a platelet microstructure showing enhance fracture toughness. In the present work, recent improvement of the mechanical behaviour of these materials at ambient and high temperatures is reported. By means of a surface oxidation treatment in air it is possible to obtain four-point bending strengths in excess of 1 GPa, and the strength retention at high temperatures is significantly improved.

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빛의 조사기간으로 본 호기성 고율 안정조 프로세스의 영양물질 제거 (The Nutrients Removal in Aerobic High Rate Ponds Through the Lighting Period)

  • 공석기
    • 환경위생공학
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    • 제11권1호
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    • pp.83-91
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    • 1996
  • It is not too much to say that the territorial inhabitants' concerns are wholly c concentrated on the environmental preservation-problem and development-problem in Korea given effect to the local self-government system. At a time like this I was studied the effect on nutrients removal through lighting period in aerobic high rate pond and we know that waste stabilization pond method is the most economical and energy saving wastewater treatment technology than others. At the results which was studied through operating the reactor-l artifically main-tained at a temperature, $25^{\circ}C$, a light intensity, 3000lux, and a lighting period, 24hrs and the reactor-2 artifically maintained at a tern야rature, $25^{\circ}C$ and a light intensity 3000lux, and a lighting period period, 12hrs, It has appeared for 24hrs.-lighting period -reactor-1 to be prior to the reactor-2. The attained results are that 1. reactor-1 is prior to reactor-2 on oxygen-generation 2. reactor-1 is prior to reactor-2 on algal production 3. COD removal efficiency, 90.76%, T-N removal efficiency, 80%, T-P removal e efficiency, 74.47 % in reactor-2, in reactor-1 COD removal efficiency, 94.85 %, T-N removal efficiency, 98.07%, T-P removal efficiency, 72.13% are, so the treatment efficiency of reactor-1 is more excellent than things of reactor-2 4. it appeared that the detention time is 8, 9days.

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Preparation of Novel T-type Polyurethanes with High Thermal Stability of Second Harmonic Generation and Their Nonlinear Optical Properties

  • Jang, Han-Na;Lee, Ga-Young;Lee, Ju-Yeon
    • Bulletin of the Korean Chemical Society
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    • 제29권4호
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    • pp.811-816
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    • 2008
  • 2,5-Di-(2'-hydroxyethoxy)benzylidenemalononitrile (3) was prepared and polymerized with 2,4-toluenediisocyanate and 3,3'-dimethoxy-4,4'-biphenylenediisocyanate to yield novel T-type polyurethanes 4 and 5 containing 2,5-dioxybenzylidenemalononitrile, nonlinear optical (NLO)-chromophores as part of the polymer backbones. Polyurethanes 4 and 5 were soluble in common organic solvents such as acetone and N,Ndimethylformamide and showed a thermal stability up to $250{^{\circ}C}$ with glass-transition temperatures ($T_g$) in the range $119-146{^{\circ}C}$. The second harmonic generation (SHG) coefficients ($d_{33}$) of poled polymer films at 1064 nm fundamental wavelength were around $5.82{\times}10^{-9}$ esu. The dipole alignment exhibited high thermal stability up to $T_g$, and there was no SHG decay below $140{^{\circ}C}$ due to the partial main-chain character of the polymer structure, which was acceptable for nonlinear optical device applications.

양송이 푸른곰팡이병균(Trichoderma spp.)의 생장에 미치는 요인과 방제법 (Factors Affecting Growth of Trichoderma spp. with Special Reference to Control of Green Mildew in Agaricus bisporus)

  • 박원목;김동수;박용환;정후섭
    • 한국응용곤충학회지
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    • 제10권2호
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    • pp.91-95
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    • 1971
  • 본 시험은 우리나라에서 발생하는 푸른곰팡이병균의 종의 빈도와 발병환경 및 방제법을 구명코져 실시하였다. 시험결과 Trichoderma koningi, T. lignorum, T. glaucum과 미동정의 1종등 4종의 병원균이 분리되었고 이들의 빈도는 각각 $50\%\;32\%,\;13\%$$5\%$이었다. 푸른곰팡이병균은 감자배양액, 왁스만배양액과 리차드배양액에서 생육이 잘 되었으며 중성-염기성배지에서는 생육이 불량한 반면 산성에서 생육이 왕성하였으며 최적산도는 pH4였다. 양송이 수확기간 중 재배사내의 온도는 $15^{\circ}C$내외 일 때 본명의 발생이 적었고 수량이 많으며 $20^{\circ}C$이상에서는 본병의 발생이 격심하였다. 푸른곰팡이병균은 복토흙 소독시 $70^{\circ}C$에서 60분, 혹은 $80^{\circ}C$에서 30분간 열처리하므로서 완전히 사멸하였고 퇴비 후발효 과정에서도 사멸되었다.

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운동 강도의 차이가 제2형 당뇨병 환자와 비만인의 초과산소 섭취량, 안정 시 대사량 및 생화학적 변인에 미치는 영향 (Effects of Different Exercise Intensity on Excess Post Exercise Oxygen Consumption (EPOC), Resting Metabolic Rate (RMR), and Biochemical Variables in Obese and NIDDM Patients)

  • 곽이섭;구우영;유병인;진영완;최경석;조준용;우진희;황혜진
    • 생명과학회지
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    • 제18권10호
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    • pp.1455-1463
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    • 2008
  • The purpose of this study was to evaluate the effect of various exercise intensity on Excess post exercise energy expenditure (EPEE), Resting Metabolic Rate (RMR),thyroid hormonal changes and biochemical variables in obese and NIDDM patients. The subject of the present study were divided into four groups and four periods: trained (T; n=10), control (C; n=10), obese (O; n=10) and NIDDM (N; n=10) group. And the periods were divided as follows; Resting (RE), Maximal (MA), High intensity (HI), and Low intensity (LI). There was significant difference in RMR among different intensity of exercise. in the T (p<0.05) not in the C, O, and N groups. however, there was no significant different percent body fat among all groups. In the energy expenditure, there was significant different among C, O, N groups compare to T in HIEE (high intensity exercise energy expenditure), LIEE (low intensity exercise energy expenditure), HIEEPE (high intensity exercise energy expenditure post exercise) and LIEEPE (low intensity exercise expenditure post exercise). In the hormonal level, there was significant different in T4 level in the T group at LI period and there was also significant difference in T4, Free T3, & Free T4 levels in T group at LI period, however there was no significant different in the O and N groups except LI period. In the fatigue variables, there was significant different in lactate and ammonia levels in the N group in the period of HI compare to C. The present cross-sectional study was design to investigate the relationship between exercise intensity and RMR in four groups. The focus of this investigation was to compare RMR in aerobically trained (T), control (C), obese (O) and NIDDM (N) group. The relationship among RMR, exercise intensity and percent body fat would best be investigated using Meta Lyzer 3B, MMX3B and body composition analyzer. Each subject completed measurement of percent body fat, RMR, hormone in the period of maximal oxygen uptake exercise (MA), high intensity exercise (HI), and low intensity exercise (LI). From the results, High and Low intensity of exercise, there was a trend for an increased RMR (kcal/day) in the trained groups and control group (in case of LI) not for the obese and N groups. This is best explained not by the reduced percent body fat but by the highly induced energy expenditure (during exercise and post exercise energy expenditure) and increased T4, Free T3, and Free T4 hormonal levels in the low intensity exercise for the T group and sometimes C group.

통조림에 주입된 유지중 Trans 지방산 함량에 관한 연구 (A Study on Trans Fatty Acids Contents of Vegetable Oils Added to Can)

  • 안미영;안명수
    • 한국식품조리과학회지
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    • 제5권1호
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    • pp.69-74
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    • 1989
  • 참치기름담금통조림과 굴, 홍합훈제기름담금통조림을 구입하여 Glass Capillary Gas Chromatography (Hewlett Packard, 5880 A)로 분석한 trans 지방산 함량과 산가, 과산화물가, 요오드가, 검화가 측정으로 관찰된 이화학적 성질의 변화는 다음과 같다. 1. 면실유가 주입된 참치, 굴, 홍합통조림에서 검출된 trans지방산의 대부분은 t,c-18:2이며 대두유가주입된 참치통조림에서 검출된 trans 지방산은 t,c-18:2 뿐만 아니라 c,c,t-18:3과 t,t,c-18:3도 소량 존재하였다. 2. Trans 지방산의 총평균 함량은 대두유가 주입된 참치통조림에서 2.26%로 가장 높았다. 또한 참치통조림의 경우 주입된 면실유나 대두유 모두 유통기간 긴 것에서 총 trans지방산 함량이 다소 더 높은 값을 보인 반면, 굴, 홍합통조림에서는 총 trans지방산 함량도 낮으면서 유통기간 중 변화도 거의 없는 것으로 나타났다. 3. 통조림에 주입된 유지의 유통기 간 중 산패도는 1년 내외의 기간에서는 산가가 0.5∼2.0 정도, 과산화물가는 0.6∼3.5 meq/kg oil 정도로 나타나 안정된 상태를 유지하고 있는 것으로 나타났다.

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Methylenetetrahydrofolate Reductase Genetic Polymorphisms and Esophageal Squamous Cell Carcinoma Susceptibility: A Meta-analysis of Case-control Studies

  • Wen, Yuan-Yuan;Yang, Shu-Juan;Zhang, Jian-Xing;Chen, Xin-Yue
    • Asian Pacific Journal of Cancer Prevention
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    • 제14권1호
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    • pp.21-25
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    • 2013
  • Background: Genetic factors and environmental factors play a role in pathogenesis of esophageal squamous cell carcinoma (ESCC). Previous studies regarding the association of folate intake and Methylenetetrahydrofolate reductase C677T polymorphism with ESCC was conflicting. We conducted a meta-analysis to investigate the association of MTHFR C677T and folate intake with esophageal cancer risk. Methods: MEDLINE, EMBASE and the Chinese Biomedical Database were searched in our study. The quality of studies were evaluated by predefined scale, and The association of polymorphisms of MTHFR C677T and folate intake and ESCC risk was estimated by Odds ratio (ORs) with 95% confidence intervals (CIs). Results: 19 studies (4239 cases and 5575 controls) were included for meta-analysis. A significant association was seen between individuals with MTHFR 677 CT [OR(95%)=1.47(1.32-1.63)] and TT [OR(95%)=1.69(1.49-1.91)] genotypes and ESCC risk (p<0.05). Low intake of folate had significantly higher risk of esophageal cancer among individuals with CT/TT genotype [OR(95%)=1.65(1.1-2.49)], while high intake of folate did not find significant high risk of esophageal cancer among individuals with CT/TT genotype [OR(95%)=1.64 (0.82-3.26)]. Conclusions: Our meta-analysis indicated the folate intake and MTHFR 677CT/TT are associated with the risk of ESCC, and folate showed a significant interaction with polymorphism of MTHFR C677T.

Ag와 Au가 혼합된 $Bi_{1.84}\;Pb_{0.34}\;Sr_{1.91}\;Ca_{2.03}\;Cu_{3.06}\;O_{10+\delta}$ 산화물 고온초전도체의 초전도특성 (Composite Effect of Ag and Au in the $Bi_{1.84}\;Pb_{0.34}\;Sr_{1.91}\;Ca_{2.03}\;Cu_{3.06}\;O_{10+\delta}$(110K Phase) High-Tc Superconductor)

  • 이민수
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제52권6호
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    • pp.241-248
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    • 2003
  • $Bi_{1.84}Pb_{0.34}Sr_{1.91}Ca_{2.03}Cu_{3.06}O_{10+\delta}$ high $T_{c}$ superconductors containing Ag as an additive were fabricated by a solid-state reaction method. The superconducting properties, such as the structural characteristics, the critical temperatures, the grain size and the image of mapping on the surface were investigated. Samples with Ag and Au of 50 wt% each were sintered at various temperature(820~$850^{\circ}C$). The structural characteristics, the microstructure of surface and the critical temperature with respect to the each samples were analyzed by XRD and SEM, EDS and four-prove methode respectively. The critical temperature showed the result which the Ag additive samples are higher than Au additive samples. The microstructure of the surface showed the tendency which the Ag additive samples become more minuteness than Au additive samples.