Authors:F. J. Lona-Ramírez, R. Herrera-Muñoz, V. Rico-Ramírez, F. Louvier Hernández, G. Luna-Bárcenas, and G. González-Alatorre
reactivity and the biological activity of the nitroso-compound formed [ 16 ].
In the particular case of 1,1,3-nitrosotrimethylurea, whose biological activity has been reported [ 17 ], no kineticstudies on their formation have been found.
Authors:Anne G. D. Santos, Vinícius P. S. Caldeira, Mirna F. Farias, Antonio S. Araújo, Luiz D. Souza, and Allan K. Barros
has been widely used in recent years, in kineticstudies of thermal decomposition of the most varied substances. Although, this technique is subjected to various criticisms and has been questioned by several authors, a large number of articles on the
Authors:Yusuke Kano, Masa-aki Ohshima, Hideki Kurokawa, and Hiroshi Miura
Dehydrogenation of ethylbenzene (EB) was examined in the presence of CO2, and the effect of CO2 on Fe2O3, Fe–Ce, Fe–K, and Fe–Ce–K oxide catalysts was evaluated. The rate equation was derived in relation to the Langmuir–Hinshelwood
mechanism. The rate constant (k) and the relative adsorption coefficient (
Authors:M. Souza, Marta Conceição, M. Silva, L. Soledade, and A. Souza
Statins are a group of lipoproteins that
are used in medicine to treat the high cholesterol level. The effectiveness
of statins in reducing the cholesterol level is significant and in long time
scale the reduction of the cholesterol level helps to avoid the incidence
of degenerative diseases. Simvastatin and lovastatin are belonging to the
‘statins’ family, one of the pharmacologic groups used in the
control of dislipidemy. The objective of this work is the thermal stability
and kinetic study of the active forms of simvastatin and lovastatin.
Thermal data indicated that lovastatin and simvastatin are stable up
to 190 and 170°C in air and up to 205 and 203°C in nitrogen, respectively.
For melting temperatures DSC curves showed good correlation with the literature
data. Comparing the activation energies of the statins at heating rate of
10°C min–1, lovastatin is more stable
than simvastatin under the applied experimental conditions.
], somehow rhetorically ask: “What is truly the aim of kineticstudies and modelling?” They also answer, “It is evident that the aim is designing reactors which can successfully accomplish and improve the decomposition of a certain material for obtaining
Authors:A. Garrido Pedrosa, P. Pimentel, D. Araújo Melo, H. Scatena, F. Borges, A. Souza, and L. Zinner
Ln(TFA)3⋅3AZA (Ln=La, Sm, Er; TFA=trifluoroacetate and AZA=2-azacyclononanone)compounds were synthesized and characterized by microanalytical procedures, IR spectroscopy, X-ray powder
diffraction, and thermal analysis. A kinetic study using La, Sm and Er thermogravimetric curves was carried out aiming to
proposing a mechanism for the thermal decomposition of such complexes.
The paper deals with a kinetic study of crystal growth in gelatin and agar gels, using a technique based on radioactive tracers.204TlCl,204TlBr,204TlI,60CoC2O4 and60CoH4C4O6 crystals in gels have been obtained. The global kinetic process of appearance of crystals has been found to be made up of two distinct stages: diffusion of the ions in the gel and crystallization, having different rate constants.
Authors:F. Fraga, V. Soto, J. Blanco-Méndez, A. Luzardo-Alvarez, E. Rodríguez-Núñez, J. Martínez-Ageitos, and M. Pérez
Knowledge of the the kinetic study of chitosan/genipin
allow to know the different effects that time and temperature have on the
cure reaction of the material.
The total enthalpy of reaction,
the glass transition temperature and the partial enthalpies have been determined
using DSC in dynamic mode. Two models, one based on chemical kinetics and
the other accounting for diffusion were used. The incorporation of the diffusion
factor in the second model allowed for the cure kinetics to be predicted the
whole range of conversion.
The kinetics of adsorption of chromate ions has been investigated radiometrically over a wide range of concentration of chromate ions (10–6–10–2M) and temperature (303–323 K). The kinetics of the process follows essentially a first order rate law with respect to adsorptive concentration and obeys the Freundlich adsorption isotherm in the concentration range studied. In addition, the kinetics of desorption of the preadsorbed species also follows a first order rate law and the activation energy for desorption is greater than that of the adsorption process. On the basis of an adsorption kinetic study, the thermodynamic parameters have been calculated. Infrared spectroscopy has shown the chemical interaction of chromate ions on the surface of MnO2.
Authors:Hugo Rojas, Gloria Borda, María Brijaldo, Patricio Reyes, and Jesús Valencia
included in this paper. To carry out the kineticstudy over the catalyst only one variable was modified in each experiment, keeping constant all the others. The effect of m -dinitrobenzene concentration was studied in the concentration range from 0.025 to