• Title/Summary/Keyword: Arrhenius parameters

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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 investigation of Magnetohydrodynamic nanofluid flow with Arrhenius energy activation

  • Sharif, Humaira;Khadimallah, Mohamed A.;Naeem, Muhammad Nawaz;Hussain, Muzamal;Mahmoud, S.R.;Al-Basyouni, K.S.;Tounsi, Abdelouahed
    • Advances in nano research
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    • v.10 no.5
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    • pp.437-448
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    • 2021
  • In this article, an analytically and numerically 3D nanoliquid flow by a porous rotatable disk is presented in the presence of gyrotactic microorganisms. The mathematical model in the form of partial differential system is transmuted into dimensionless form by utilizing the appropriate transformation. The homotopy analysis approach is applied to attain the analytic solution of the problem. The effect of promising parameters on velocity distribution, temperature profile, nanoparticles volume fraction and motile microorganism distribution field are evaluated through graphs and in tabular form. The existence of Brownian motion and thermophoresis impacts are more proficient for heat transfer enhancement. Further the unique features like heat absorption/generation and energy activation are also examined for the present flow problem. The obtained results are compared with the earliear investigation to check the accuracy of present model.

Preparation and Rheological Properties of Chitin and Chitosan -2. Effects of shear rate, temperature, concentration and salts on the viscosity of chitosan solution- (갑각류 외피의 유효이용을 위한 Chitin 및 Chitosan의 제조와 물성학적 특성에 관한 연구 -2. Chitosan 용액의 점도에 미치는 전단속도, 온도, 농도 및 염의 영향-)

  • LEE Keun-Tai;PARK Seong-Min;BAIK Oon-Doo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.28 no.4
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    • pp.397-400
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    • 1995
  • Effects of rheological parameters, such as shear rate, temperature, concerntration, salts on the apparent viscosity of chitosan(deacetylation degree: $84\%$, Mw: 267,000) dissolved in acetate buffer(pH 4.5) were investigated. Rheologiral properties of chitosan solution from cuticle of red snow crab (Chinonecetes japonicus) are as follows. $0.5\%$ chitosan in 0.1M acetate buffer (pH 4.5) solution showed Bingham flow having hysteresis loop. It's flow equation was $\sigma=0.757+19.6_\gamma(r^2=0.99)$. The viscosity of chitosan solution is exponentially increased with its concentration, and showed Arrhenius dependence with respect to the temperature $(10^{\circ}C-40^{\circ}C).$ When various salts were added to chitosan solution, the viscosity decreased as the concentration of counterion increased. But the type ot counterions itself does not have any significant effects on the viscosity.

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A Kinetic Study on the Growth of Nanocrystalline Diamond Particles to Thin Film on Silicon Substrate

  • Jung, Doo-Young;Kang, Chan-Hyoung
    • Journal of the Korean institute of surface engineering
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    • v.44 no.4
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    • pp.131-136
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    • 2011
  • A kinetic study has been made for the growth of nanocrystalline diamond (NCD) particles to a continuous thin film on silicon substrate in a microwave plasma chemical vapor deposition reactor. Parameters of deposition have been microwave power of 1.2 kW, the chamber pressure of 110 Torr, and the Ar/$CH_4$ ratio of 200/2 sccm. The deposition has been carried out at temperatures in the range of $400\sim700^{\circ}C$ for the times of 0.5~16 h. It has been revealed that a continuous diamond film evolves from the growth and coalescence of diamond crystallites (or particles), which have been heterogeneously nucleated at the previously scratched sites. The diamond particles grow following an $h^2$ = k't relationship, where h is the height of particles, k' is the particle growth rate constant, and t is the deposition time. The k' values at the different deposition temperatures satisfy an Arrhenius equation with the apparent activation energy of 4.37 kcal/mol or 0.19 eV/ atom. The rate limiting step should be the diffusion of carbon species over the Si substrate surface. The growth of diamond film thickness (H) shows an H = kt relationship with deposition time, t. The film growth rate constant, k, values at the different deposition temperatures show another Arrhenius-type expression with the apparent activation energy of 3.89 kcal/mol or 0.17 eV/atom. In this case, the rate limiting step might be the incorporation reaction of carbon species from the plasma on the film surface.

The Recovery of Silver from Thiourea Leaching Solution by Cementation Technique (침전법을 이용한 Thiourea 용출용액으로부터 Silver 회수)

  • Kim, Bong-Ju;Cho, Kang-Hee;Choi, Nag-Choul;Park, Cheon-Young
    • Economic and Environmental Geology
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    • v.46 no.1
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    • pp.29-37
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    • 2013
  • In order to apply the silver cementation method using Fe powder from pregnant thiourea leaching solution. Parameters such as the amount of Fe powder addition, agitation speed, and temperature were investigated. The silver cementation rate was increased by the increasing of Fe powder addition, agitation speed, and temperature. The highest silver cementation rate was found when the addition of Fe powder was 50 g/L at the agitation speed of 500 rpm. The silver cementation rate increase with increasing temperature according to the Arrhenius equation and obeys $1^{st}$ order kinetics. The activation energy from the kinetics data was found to be between 13.73 KJ/mol and 17.02 KJ/mol. In the XRD analysis, goethite was detected in the precipitate of the thiourea leach solution. This indicates that an oxidation-reduction reaction had occurred in the thiourea solution due to the addition of the Fe powder.

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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Accelerated Heat Aging Test for Predicting Useful Lifetime of Elastomeric Rearing (가속 열 노화시험에 의한 탄성받침용 합성고무의 수명 예측에 관한 연구)

  • Park, K.H.;Park, J.H.;Lee, H.H.;Kwon, Y.I.
    • Journal of Applied Reliability
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    • v.4 no.2
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    • pp.73-90
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    • 2004
  • We performed the heat aging test to predict the useful lifetime of Elastomeric Bearing Chloroprene Rubber (CR) used for supporting bridge. During the test, we measured elongation that are influenced by temperature and aging time. The failure of a test piece is defined as the point at which the elongation reaches to 75% of the initial value. This failure criterion is based on KS F 4420: 1998 (Elastomeric Bearing for bridge). Through the accelerated heat aging test, we found that the Arrhenius relationship and the Weibull lifetime distribution are appropriate as the life-temperature relationship and lifetime distribution of the CR, respectively. Using the Arrhenius -Weibull model, the parameters of the model are estimated and the lifetime of the CR at use condition is predicted.

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A Study of Transonic Premixed Combustion in a Diverging Channel Using Asymptotic Analysis (점근해석을 이용한 확대형 채널 내의 천음속 예혼합 연소에 관한 연구)

  • Lee, Jang-Chang
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.8
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    • pp.75-83
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    • 2005
  • A steady transonic dilute premixed combustion in a diverging channel is investigated by using asymptotic analysis. This model explores the nonlinear interactions between the near-sonic speed of the flow, the small changes in geometry from a straight channel, and the small heat release due to the one-step first-order Arrhenius chemical reaction. The reactive flow is described by a nonhomogeneous transonic small-disturbance (TSD) equation coupled with an ordinary differential equation for the calculation of the reactant mass fraction in the combustible gas. Also the asymptotic analysis reveals the similarity parameters that govern the reacting flow problem. The results show the complicated nonlinear interaction between the convection, reaction, and geometry effects and its effect on the flow behavior.

Combustion Kinetics of Pulverized Indian Coal-Char in Different CO2-O2 Mixture Isothermally (여러 CO2-O2 혼합기체에서 인도산 분말숯의 등온 연소반응)

  • Saravanan, V.;Shivakumar, R.;babu, P. Niruguna;Ramakrishna
    • Journal of the Korean Chemical Society
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    • v.53 no.6
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    • pp.635-639
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    • 2009
  • Experimental work was carried out to study the combustion kinetics of the Indian coal-char in the varying mixture of carbon dioxide-oxygen ($CO_2-O_2$). The coal sample was pulverized and sieved to less than 58 microns and charred using volatile furnace by passing the nitrogen gas. The experiments were carried out using the Thermo Gravimetric Analyzer (TGA-50) at CPRI, Bangalore, different proportions of ($CO_2-O_2$) gas was allowed in to the TGA-50 (80-20, 60-40, 40-60, 20-80) mole basis were used to study the combustion kinetics of coal Isothermally, kinetic parameters like Activation energy (E) and the pre-exponential factors (A) are calculated using the unification approach and modified Arrhenius equation.

A Kinetic Study of Thermal-Oxidative Decomposition of Waste Polyurethane (폐폴리우레탄의 열적 산화분해에 대한 속도론적 연구)

  • Jun, Hyun Chul;Oh, Sea Cheon;Lee, Hae Pyeong;Kim, Hee Taik
    • Applied Chemistry for Engineering
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    • v.17 no.3
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    • pp.296-302
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    • 2006
  • The kinetics of the thermal-oxidative decomposition of waste polyurethane (PU) according to oxygen concentration has been studied using a non-isothermal thermogravimetric technique at several heating rates from 10 to $50^{\circ}C/min$. A kinetic model accounting for the effects of the oxygen concentration by the differential and integral method based on Arrhenius equation was proposed to describe the thermal-oxidative decomposition of waste PU. To obtain the information on the kinetic parameters such as activation energy, reaction order, and pre-exponential factor, the thermogravimetric analysis curves and its derivatives have been analyzed using the kinetic analysis method proposed in this work. From this work, it was found that reaction orders for oxygen concentration had a negative sign, and activation energy decreased as the oxygen concentration increased. It was also found that the kinetic parameters obtained from the integral method using the single heating rate experiments varied with heating rates. Therefore, it is thought that the differential method using the multiple heating rate experiments more effectively represents the thermal-oxidative decomposition of waste polyurethane.