Authors:X. Cao, Z. Wang, X. Yang, Y. Liu, and C. Wang
The kinetics of protein thermal transition is of a significant interest from the standpoint of medical treatment. The effect
of sucrose (0–15 mass%) on bovine serum albumin denatured aggregation kinetics at high concentration was studied by the iso-conversional
method and the master plots method using differential scanning calorimetry. The observed aggregation was irreversible and
conformed to the simple order reaction. The denaturation temperature (Tm), the kinetic triplets all increased as the sucrose concentration increased, which indicated the remarkable stabilization
effect of sucrose. The study purpose is to provide new opportunities in exploring aggregation kinetics mechanisms in the presence
Authors:Xiaomin Cao, Yun Tian, Zhiyong Wang, Yuwen Liu, and Cunxin Wang
The kinetics of bovine serum albumin (BSA) denaturation in the absence and the presence of urea was studied by the iso-conversional
method and the master plots method using differential scanning calorimetry (DSC). The observed denaturation process was irreversible
and approximately conformed to the simple order reaction, and the denaturation did not follow rigorously first-order kinetic
model or other integral order reaction models. The denaturation temperature (Tm), apparent activation energy (Ea), approximate order of reaction (n), and pre-exponential factor (A) all distinctly decreased as the 2 mol L−1 urea was added, which indicated that the urea accelerated the denaturation process of BSA and greatly reduced thermal and
kinetic stability of BSA. This study also demonstrated that the iso-conversional method, in combination with the master plots
method, provides a valuable and useful approach to the study of the kinetic process of protein denaturation.
Authors:X. Cao, X. Yang, J. Shi, Y. Liu, and C. Wang
The effect of glucose (0–15 mass%) on the kinetics of bovine serum albumin (BSA) denatured aggregation at high concentration
in aqueous solution has been studied by differential scanning calorimetry. The observed denatured aggregation process was
irreversible and could be characterized by a denaturation temperature (Tm), apparent activation energy (Ea), the approximate order of reaction, and pre-exponential factor (A). As the glucose concentration increased from 0 to 15 mass%, Tm increased, Ea also increased from 514.59409±6.61489 to 548.48611±7.81302 kJ mol−1, and A/s−1 increased from 1.24239E79 to 5.59975E83. The stabilization increased with an increasing concentration of glucose, which was
attributed to its ability to alter protein denatured aggregation kinetics.
The kinetic analysis was carried out using a composite procedure involving the iso-conversional method and the master plots
method. The iso-conversional method indicated that denatured aggregation of BSA in the presence and absence of glucose should
conform to single reaction model. The master plots method suggested that the simple order reaction model best describe the
process. This study shows the combination of iso-conversional method and the master plots method can be used to quantitatively
model the denatured aggregation mechanism of the BSA in the presence and absence of glucose.
Authors:Y. Duan, J. Li, X. Yang, X. Cao, L. Hu, Z. Wang, Y. Liu, and C. Wang
The thermal decomposition of strontium acetate hemihydrate has been studied by TG-DTA/DSC and TG coupled with Fourier transform
infrared spectroscopy (FTIR) under non-isothermal conditions in nitrogen gas from ambient temperature to 600°C. The TG-DTA/DSC
experiments indicate the decomposition goes mainly through two steps: the dehydration and the subsequent decomposition of
anhydrous strontium acetate into strontium carbonate. TG-FTIR analysis of the evolved products from the non-oxidative thermal
degradation indicates mainly the release of water, acetone and carbon dioxide. The model-free isoconversional methods are
employed to calculate the Ea of both steps at different conversion α from 0.1 to 0.9 with increment of 0.05. The relative constant apparent Ea values during dehydration (0.5<α<0.9) of strontium acetate hemihydrate and decomposition of anhydrous strontium acetate (0.5<α<0.9)
suggest that the simplex reactions involved in the corresponding thermal events. The most probable kinetic models during dehydration
and decomposition have been estimated by means of the master plots method.
Authors:Shi Jingyan, Wang Zhiyong, Liu Yuwen, and Wang Cunxin
4000–400 cm −1 using KBr pellet technique.
The thermal kinetic analysis was carried out by the isoconversional method and the masterplotsmethod, which had been described in details in other studies [ 13 ]. So
Advanced software (TKS-SP2.0 version) for thermal and kinetic analysis, for determining the non-isothermal kinetic parameters
of heterogeneous processes has been developed. The dynamic handle of conversion degree steps and ranges, heating rates and
kinetic models, makes the evaluation of the kinetic parameters much faster, for TG, TPR and dilatometry experiments. The standard
procedure for evaluating the kinetic triplet was implemented; several linear isoconversional methods (from generalized KAS
to FWO, Li-Tang and Friedmann methods), IKP method, Perez-Maqueda et al. criterion (both by Differential equation) and Master plots method. The software is designed mainly for data processing of
experimental files, but may also import other already transformed numeric data.
Authors:S. Jingyan, L. Jie, D. Yun, H. Ling, Y. Xi, W. Zhiyong, L. Yuwen, and W. Cunxin
The thermal behavior of nicotinic acid under inert conditions was investigated by TG, FTIR and TG/DSC-FTIR. The results of
TG/DSC-FTIR and FTIR indicated that the thermal behavior of nicotinic acid can be divided into four stages: a solid-solid
phase transition (176–198°C), the process of sublimation (198–232°C), melting (232–263°C) and evaporation (263–325°C) when
experiment was performed at the heating rate of 20 K min−1. The thermal analysis kinetic calculation of the second stage (sublimation) and the fourth stage (evaporation) were carried
out respectively. Heating rates of 1, 1.5, 2 and 3 K min−1 were used to determine the sublimation kinetics.
The apparent activation energy, pre-exponential factor and the most probable model function were obtained by using the master
plots method. The results indicated that sublimation process can be described by one-dimensional phase boundary reaction,
g(α)=α. And the ‘kinetic triplet’ of evaporation process was also given at higher heating rates of 15, 20, 25, 30 and 35 K min−1. Evaporation process can be described by model of nucleation and nucleus growing,
Authors:Dragica M. Minić, Maja T. Šumar-Ristović, Đenana U. Miodragović, Katarina K. Anđelković, and Dejan Poleti
, the conversion function for all three steps of the degradation and theoretically proposed conversion functions [ 36 ], were reconstructed numerically by applying the “masterplot” method [ 44 ]. According to this method, for a single-step process, the