• Title/Summary/Keyword: Arrhenius plots

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Hydrogen Permeation of SiC-CeO2 Composite Membrane by Dip-coating Process

  • Park, Jihye;Jung, Miewon
    • Journal of the Korean Ceramic Society
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    • v.50 no.6
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    • pp.485-488
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    • 2013
  • A SiC-$CeO_2$ composite membrane was successfully fabricated using an ally-hydridopolycarbosilane (AHPCS) binder and treated by dip-coating at 60 times with a $CeO_2$ sol solution. The dip-coated SiC membrane was calcined at 773 K and then sintered at 1173 K under an air atmosphere. The coated membrane was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and a BET surface analysis. The difference in permeation performance between $H_2$ and CO gases was measured by varying the temperature. The permeation flux of $H_2$ on the SiC membrane with layered $CeO_2$ was obtained as $8.45{\times}10^{-6}\;mol/m^2sPa$ at room temperature. The CO permeation flux was $2.64{\times}10^{-6}\;mol/m^2sPa$ at room temperature. The reaction enthalpy (${\Delta}H^{\circ}$) for the hydrogen permeation process was calculated as -7.82 J/mol by Arrhenius plots.

Thermal Inactivation Kinetics of Tyichoderma viride Cellobiohydrolase Determined by Enzyme Linked Immunosorbent Assay and Residual Enzyme Assay (면역학적 방법에 의한 Cellobiohydrolase의 열역학적 특성)

  • 오태광;박관화
    • Microbiology and Biotechnology Letters
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    • v.17 no.4
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    • pp.365-369
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    • 1989
  • Thermal inactivation of Tyichoderma viride cellobiohydrolase was investigated by immunoassay and residual enzyme assay such as carboxymethyl cellulase (CMCase) and filter paper degradation activity (FPase). Arrhenius plots of cellobiohydrolase were appeared as straight line. The Z-values of cellobiohydrolase calculated by CMCase, FPase and immunoassay were 5.2$^{\circ}C$, 6.4$^{\circ}C$ and 5.8$^{\circ}C$, respectively. The thermodynamic parameters obtained from FPase were better agreement with those of immunoassay than CMCase assay.

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The Stability of Piroxicam in Propylene Glycol (프로필렌글리콜에서의 피록시캄의 안정성)

  • Shin, Young-Shin;Shin, Young-Hee;Lee, Chi-Ho
    • Journal of Pharmaceutical Investigation
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    • v.18 no.4
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    • pp.203-208
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    • 1988
  • The stability and solubility of piroxicam in propylene glycol (PG), polyethylene glycol (PEC), and PG-water cosolvents have been studied by using high performance liquid chromatography. The degradation rate followed an apparent first-order kinetic and the reaction rate constants at 70, 80, and $90^{circ}C$ were determined. From these rate constants, the activation energy and the rate constant of piroxicam at $25^{circ}C$ in pure PG calculated by Arrhenius equation were 23.34 kcal/mole and $7.0\;{\times}\;10^{-4}\;day^{-1}$, respectively. Both of PG and PEG increased the solubility of the drug, but PEG was more effective.

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Seasonal Variation in the $Na^+$,$K^+$-ATPase Activity in Frog (Rana dybowskii) Brain (개구리 뇌에서 $Na^+$,$K^+$- ATPase 특성의 계절적 변화)

  • 김미승;임욱빈
    • The Korean Journal of Zoology
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    • v.38 no.4
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    • pp.449-456
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    • 1995
  • Seasonal changes in the activity and charaderistics of brain Na+, K+-ATPase and Mg2+-AWase were investigated in frog (Rana dybowskii) The brain Na+, K+-ATPase adivity during hibernation was similar to that in active period in frogs. The Na+, K+-AWase activity increased in December and March, when the frogs enter into and awake from the hibernation. Over 5-35$^{\circ}C$ temperature range, Na+, K+-ATPase showed non4inear Arrhenius kinetics throughout the year. The brain Mg2+-ATPase activity decreased during hibernation, but markedly increased in March. The Arrhenius plots for Mg2+-AWase activity were linear in frogs both in torpid and active state. The ratio of Na+, K+-AWase activity at 15~C to at 35~C did not change during hibernation. The sensitivity of Na+, K+-AWase to ouabain was also unchanged throughout the year. These results indicate that the activity and charaderistics of brain Na+, K+-AWase remain unchanged during hobernadon in frog.

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Kinetic Studies on the Ageing of Aluminum Hydroxide Gel (수산화알루미늄.겔의 노화에 관한 연구)

  • 유병술
    • YAKHAK HOEJI
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    • v.6 no.2
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    • pp.7-12
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    • 1962
  • The rats of thermal ageing at elevated temperatures and heats of activation of aluminum hydroxide gel have been determined. The ageing was expressed in terms of diminution of acid consuming capacity. Although the actual rates of ageing were different by the samples, the slopes of their Arrhenius plots were the same. This may indicate similarity of ageing mechanisms and heats of activation of samples. The heat of activation was the mangitude of 30 Kcal/mole. Thus, rates of ageing of aluminum hydroxide gel may be greatly accelerated at elevated temperatures.

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Thermal Insulation Life Prediction of EPDM rubber Used for Electrical Insulation (고압절연용 EPDM rubber의 내열수명 예측)

  • Lee, Chul-Ho;Jeon, Young-Jun;Kim, Sang-Wook
    • Proceedings of the KIEE Conference
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    • 1997.07d
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    • pp.1408-1410
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    • 1997
  • Arrhenius plots are useful in predicting long-term use temperatures of organic materials and in choosing parameters for accelerated aging. The effects of antioxidant on the heat resistance and temperature index of EPDM rubber used for electrical insulation were investigated. The short-time points were obtained by 50% retention of elongation at break.

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Studies on the Phase Separation of the Borosilicate Glass by Addition of Titanium Dioxide ($TiO_2$ 첨가에 따른 붕규산 유리의 분상에 관한 연구)

  • 박용완;민병욱
    • Journal of the Korean Ceramic Society
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    • v.18 no.4
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    • pp.257-261
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    • 1981
  • The tendency of glass containing titanium-dioxide to separate into two phases can be attributed to a change of the coordination number of titanium from six to four on increase of temperature and to "freezing" of the high temperature four fold coordination on cooling of the melt. Addition of TiO2 to the basic glass 8.7 $Na_2O$ 22.4B2O3 68.9 $SiO_2$ was varied 5 to 25 parts. The phase separation in the temperature range of transformation was examined with each heating temperature and soaking time. As the experimental results, the most distinct phase separation were obtained from alkali extraction method when $TiO_2$ was added 15 parts. The apparant activation energy was 30.5 Kcal/mole by alkali extraction method derived from Arrhenius plots.ius plots.

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Computer Simulation of Ionic Conductivity Application to Glassy Solid Electrolytes by Monte-Carlo Method (Monte Carlo 방법에 의한 유리 고체전해질의 이온전도도에 관한 전산 모사)

  • 최진삼;서양곤;강은태
    • Journal of the Korean Ceramic Society
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    • v.31 no.3
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    • pp.241-248
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    • 1994
  • The ionic conductivity in glassy systems were calculated as functions of temperature and ion concentration using Monte-Carol method considering interaction between neighbouring ion-site occupancies, {{{{ rho }}'s. Also the vacancy availability factor, V, the effective jump frequency factor, W, and the charge correlation factor, fc, have been investigated. The Arrhenius plot could be obtained from the ln {{{{ sigma }}T vs. 1/T* plots and was in exellent agreement with the experimental observations. The effects of the various types of potential well on the ionic conductivity have been considered. The activation energy Eg for ion motion in the glass was 1.3│ε│from the ln {{{{ sigma }}T vs. 1/T* plots.

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Effect of Cure System on the Life-time of Hydrogenated NBR O-ring using Intermittent Compression Stress Relaxation(CSR) (간헐 압축응력 완화를 이용한 가교 구조가 hydrogenated NBR 오링의 수명에 미치는 영향 연구)

  • Lee, Jin-Hyok;Bae, Jong-Woo;Kim, Jung-Su;Hwang, Tae-Jun;Choi, Yu-Seok;Baek, Kwang-Sae;Jo, Nam-Ju
    • Elastomers and Composites
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    • v.46 no.2
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    • pp.144-151
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    • 2011
  • Intermittent CSR testing was used to investigate the degradation of a hydrogenated NBR(HNBR) O-rings, and also the prediction of its life-time. The cure system of HNBR O-ring was controlled as sulfur cure and peroxide cure system. An intermittent CSR jig was designed taking into consideration the O-ring's environment under use. The testing allowed observation of the effects of friction, heat loss, and stress relaxation by the Mullins effect. Degradation of O-rings by thermal aging was observed between 100 and $120^{\circ}C$. In the temperature range of $100-120^{\circ}C$, O-rings showed linear degradation behavior and satisfied the Arrhenius relationship. The activation energy of HNBR-S was about 70.6 kJ/mol. From Arrhenius plots, predicted life-times of HNBR-S O-ring were 31.1 years and 33.7 years for 50% and 40% failure conditions, respectively. In case of HNBR-P, the activation energy was about 72.1kJ/mol, and predicted life-times were 34.0 years and 36.5 years for 50% and 40% failure conditions, respectively. The peroxide cure system showed slower degradation rate and higher activation energy than the sulfur cure system.

The Enzymatic Properties of Extracellular Adenine Deaminnse from Streptomyces sp. J-350P (Streptomyces sp. J-350P가 생산하는 세포외 Adenine Deaminase의 효소학적 성질)

  • 전홍기;박정혜;김태숙
    • Microbiology and Biotechnology Letters
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    • v.15 no.5
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    • pp.312-318
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    • 1987
  • The apparent Michaelis constant Km of extracellular adenine deaminase from Streptomyces sp. J-350P was 5.8$\times$10$^{-5}$M. The activation energy or the enzyme was calculated from Arrhenius plots for adenine and the value was 3.13 Kcal/mole. The purine analogues, 6-chloropurine, 2,6-diaminopurine, 6-bromopurine, 4-aminopyrazolo[3,4-d] pyrimidine, 6-iodopurine, and 8-bromoadenine were substrates for the enzyme. 6-Dimethylaminopurine was a competitive inhibitor of the enzyme. The enzyme was inhibited by 0.1mM of Fe$^{3+}$, Ag+, and Hg$^{2+}$ and 1 mM of $\alpha$, $\alpha$'-dipyridyl, Penta-chiorophenol, and p-chloromercuribenzoate.

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