Thermal behavior and decomposition kinetics of efavirenz under isothermal and non-isothermal conditions

Ceramic tiles were manufactured from an industrial powder batch of porcelain stoneware tiles with 0, 10, 30 and 50 mass% polishing waste and fired at 1100-1180°C. The phase evolution and microstructure of ceramic tiles with the polishing waste were investigated by X-ray diffraction, differential thermal analysis and scanning electron microscope. The result showed that introduction of the polishing waste into porcelain tiles did not cause significant variations in the phase composition and facilitated the formation of mullite phase. The activation energies of mullite crystallization calculated by the Kissinger method were 780 ± 43, 828 ± 61, 493 ± 18 and 530 ± 30 kJ mol -1 for the porcelain tiles with 0, 10, 30 and 50 mass% polishing waste, respectively. In addition, the Avrami constant, n, gradually decreased with the increasing polishing waste content, indicating that the crystallization mechanism of mullite in porcelain stoneware tiles changed from two-dimensional crystallization to onedimensional crystallization. The process of one-dimensional crystallization is more favorable to the formation of needle-shaped mullite and increases the length of mullite.

Section: Mechanism and Kinetic Parameters Of Sintercrystallizationmentioning

confidence: 71%

Effect of polishing waste additive on microstructure and foaming property of porcelain tile and kinetics of sinter-crystallization

Xian

Zeng

Cheng

et al. 2015

“…These curves show mass loss rate dependence in temperature function of isothermal, the higher the temperature lower will be the necessary time so that occur the same mass loss. The curves were used to obtain the graphic of lnt versus 1/T (K -1 ) at a constant conversion level 5.0% [57,19]. From this linear regression method, the equation for the line is y= -13800.3x+25.47 and R = 0.9993 are obtained.…”

Section: Li-tang (Lt) Methodmentioning

confidence: 99%

Thermal decomposition kinetics of the antiparkinson drug “entacapone” under isothermal and non-isothermal conditions

Mohamed

Atty

Banks

2017

The thermal decomposition kinetics of entacapone (ENT) have been investigated via thermogravimetric analysis (TGA) under non-isothermal and isothermal conditions which provide useful stability information for their processing in the pharmaceutical industry and also for predicting shelf life and suitable storage conditions. The determination of the kinetic parameters for the decomposition process under non-isothermal conditions in a nitrogen atmosphere at four heating rates (5, 10, 15, and 20 o C min-1) was performed. Kinetic parameters of the decomposition process for ENT were calculated through Friedman, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Li-Tang methods. This work demonstrates that the activation energies calculated from the decomposition reactions by different methods are consistent with each other. Moreover, the thermodynamic functions of the decomposition reaction were also calculated.

“…Despite the excellent results achieved in recent years, there are reports of resistance and side effects of these drugs, which led to a growing demand for less harmful analogous to patient health. Factors such as the quality and product stability must also be known, since they are important to ensure survival of the patient [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Kinetic study of anti-HIV drugs by thermal decomposition analysis

Ferreira

Araujo

Yoshida

et al. 2016

Kinetic study by thermal decomposition of antiretroviral drugs, Efavirenz (EFV) and Lamivudine (3TC), usually present in the HIV cocktail, can be done by individual adjustment of the solid decomposition models. However, in some cases unacceptable errors are found using this methodology. To circumvent this problem, here is proposed to use a multilayer perceptron neural network (MLP), with an appropriate algorithm, which constitutes a linearization of the network by setting weights between the input layer and the intermediate one and the use of Kinetic models as activation functions of neurons in the hidden layer. The interconnection weights between that intermediate layer and output layer determines the contribution of each model in the overall fit of the experimental data. Thus, the decomposition is assumed to be a phenomenon that can occur following different kinetic processes. In the investigated data, the kinetic thermal decomposition process was best described by R1 and D4 model for all temperatures to EFV and 3TC, respectively. The residual error adjustment over the network is on average 10 3 times lower for EFV and 10 2 times lower for 3TC compared to the best individual kinetic model that describes the process. These improvements in physical adjustment allow detailed study of the process and therefore a more accurate calculation of the kinetic parameters such as the activation energy and frequency factor. It was found E a = 75.230 kJ / mol and s -1 for EFV and E a = 103.25 kJ / mol and s -1 for 3TC.