نتایج جستجو برای: arrhenius activation energy
تعداد نتایج: 1076609 فیلتر نتایج به سال:
Growth intensity o f the green alga, Scenedesmus obliquus, was measured in autotrophic cultures, diluted once daily, between 20 and 30 °C in a light-dark cycle o f 16 : 8 h at initial optical densities between 0.02 and 1.2. Arrhenius analyses o f the results showed linear relationships be tween growth intensity and temperature below the temperature optimum. The temperature effects on growth, a...
In this paper, we demonstrate a method to investigate the temperature degradation of THz quantum cascade lasers (QCLs) based on analyzing the dependence of lasing output power on temperature. The output power is suggested to decrease exponentially with some characteristic activation energy indicative of the degradation mechanism. As a proof of concept, Arrhenius plots of power versus temperatur...
By means of superplastic tensile test above the Ac1 temperature (γ→α transformation temperature), superplastic deformation activation energy of ultrafine-grained commercial die steel CrWMn is investigated on the basis of the Arrhenius theory equation, ) / exp( 1 RT Q A m − = σ ε& , which indicates the resistance of the superplastic deformation. According to the Arrhenius equation, the activatio...
Abstract We investigated the growth mechanism of 2D Mo2C crystals by chemical vapor deposition (CVD) under various time and temperature conditions. The kinetics on Cu via were using a modified Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. To analyze surface coverage, we employed scanning electron microscopy (SEM) applied model to determine rate activation energy. exhibited temperature-dependent ...
The viscosity of glass is the most important technological property to manufactures and various applications. Practically, finding an accurate equation express behavior in entire transition temperature range tremendously challenge because it spans more than ten orders magnitude. After a brief review existing empirical equations, this work focuses on correlating silica with evolution medium-rang...
The degradation of branched-chain amino acids (valine, leucine, and isoleucine) in subcritical water was measured from 290 degrees C to 330 degrees C. The degradation process at any temperature obeyed first-order kinetics. The energy of activation for the degradation of each amino acid could be estimated according to the Arrhenius equation. The pH value of the reaction mixture increased during ...
We review work by the authors on thermal activation in nanoscopic magnetic systems. These systems present unique difficulties analyzing noise-induced escape over a barrier, including presence of nonlocal interactions, nongradient terms energy functional, and dynamical textures as initial or saddle states. begin with discussion reversal between single-domain configurations magnetization. Here tr...
The present Letter reports on self-diffusion in amorphous silicon. Experiments were done on ^{29}Si/^{nat}Si heterostructures using neutron reflectometry and secondary ion mass spectrometry. The diffusivities follow the Arrhenius law in the temperature range between 550 and 700 °C with an activation energy of (4.4±0.3) eV. In comparison with single crystalline silicon the diffusivities are tre...
Temperature-dependent photodegradation during UV-resonance Raman spectroscopy was investigated. Photodegradation was quantitatively probed by monitoring the temporal evolution of UV-resonance Raman spectra obtained from bacteriochlorophyll (BChl) showing, resonance effect at a 355-nm excitation wavelength. At 80 K, the molecular photodecomposition rate was 5-times lower than that at room temper...
The density and temperature dependence of the structural relaxation time (tau) in water was determined by inelastic ultraviolet scattering spectroscopy in the thermodynamic range (P=1-4000 bars, T=253-323 K), where several water anomalies take place. We observed an activation (Arrhenius) temperature dependence of tau at constant density and a monotonic density decrease at constant temperature. ...
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