نتایج جستجو برای: activation energies

تعداد نتایج: 476631  

M. Mehrabi M. Modarres M. Zahedifar, S. Harooni

Beryllium  oxide  (BeO)  nanopowder  was  synthesized  using  sol-gel method  and  the  effects  of  changes of  chemical  reagents  were investigated.  Because  of  tissue  equivalence  and  other  outstanding thermoluminescence  (TL) properties of  the bulk material  in X and γ dosimetry, the applicability of this nanostructure in TL dosimetry was studied  following  irradiation to  the 137 C...

Abdolreza Aroujalianii Ahmadreza Raisii

Effects of pH, temperature, and syrup concentration on color formation in glucose syrups were studied and the shelf life of syrups under various conditions was estimated. Temperatures of 5, 25, and 45 ºC, pH values of 4, 5, and 6 as well as concentrations of 30, 40, 50, 60, 70, and 80 ºBrix were examined. After 26 weeks no significant color changes were observed at 5 ºC. At 45 ºC, color formati...

This study investigates the effects of micro- and nano-sized SiC powder on the rheological behavior of Al based feedstocks for powder injection molding (PIM).  Different compositions of Al feedstocks with additions of micro and nano-SiC powder were prepared and their rheological properties were measured with a rotational rheometer. The effects of SiC content and shear rate were investigated and...

In the present research, the primary crystallization kinetics of the amorphous Fe85.3B11P3Cu0.7 alloy was analyzed using non-isothermal DSC measurements. The average and local activation energies, Ea, were determined by different isokinetic and isoconversional methods. The results obtained for activation energy in this research, show that due to the complexity of the primary crystallization pro...

The kinetics and mechanism of the reaction of 5-nitro-1H-benzo[d] imidazole to produce 6-nitro-1H-benzo[d] imidazole was studied by employing hybrid meta-density functional theory. MPWBlK/6-31+G** level calculations were carried out to obtain energies and optimize the geometries of all stationary points along the PES, and determine the harmonic vibrational frequencies. Two transition states (TS...

A. Shokuhfar, H. Arabi, S. Ahmadi, S. Nouri,

Abstract: Guinier-Preston (GP) zone formation and precipitation behavior of T1 (Al2CuLi) phase during the ageingof an Al-Cu-Li-Zr alloy was studied by differential scanning calorimetry (DSC) technique and electrical resistancemeasurement of the samples. Results show that endothermic effects in the thermograms of the alloy between 180°Cand 240°C can be related to the enthalpy of GPzones dissolut...

Fateme Asjodi Seyyed Khatiboleslam Sadr Nejad

Vanadium is distributed widely and scarcely (150 ppm) on the earth. Its major applications are in steelmaking, dye-production and catalyst-fabrication industries. With the ever-increasing demand for this metal, secondary resource-exploitation of such waste materials as spent catalysts is recommended. Many reactions are involved in vanadium-extraction from these resources. Since roasting in comp...

Journal: :Nanotechnology 2010
Toshishige Yamada Hisashi Yabutani Tsutomu Saito Cary Y Yang

Transport properties under current stress are examined for a carbon nanofiber (CNF) on an insulating substrate between tungsten-deposited gold electrodes. The temperature dependence of CNF resistance is determined based on our previously reported heat transport model. The measured devices exhibit a thermal activation behavior, suggesting transport in a disordered medium. The extracted activatio...

Journal: :Journal of agricultural and food chemistry 2006
Gordon E Anthon Diane M Barrett

Low-temperature blanching of vegetables activates the enzyme pectin methylesterase (PME), which demethylates cell wall pectins and improves tissue firmness. This temperature activation of PME has been investigated by measuring the formation of methanol in intact tissue of green beans and tomatoes. Rates of methanol formation at temperatures of 35-65 degrees C were obtained by measuring the rele...

In this study, the theoretical calculations of CO dissociation were carried out on Cu-Fe alloy surface by a full-potential method, which made more accurate results especially on the prediction of adsorption energies. This process may be governed by either a direct route or a H-assisted via HCO and COH intermediates pathways. In comparison to the pure surface Fe (100), the presence of Cu atom en...

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