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.
A short-term greenhouse pot culture study was carried out to study the agronomy efficacy of P sources for cotton crop in a
vertisol. The sources of P were single super phosphate (SSP), diammonium phosphate (DAP) and nitrophosphate tagged with 32P and applied at three rates (30, 60 and 90 kg P2O5 ha−1). The results indicated that the dry matter yield (DMY) of cotton shoot, P uptake, percent P derived from fertilizer (%Pdff)
and Avalue of the soil increased significantly with increasing fertilizer rate, whereas the percent fertilizer P utilization
(%FUP) was found to be higher at lower fertilizer rates. Among the fertilizer sources SSP was found to be superior in enhancing
DMY of cotton, P uptake and %FUP as compared to other fertilizers. %Pdff was found to be at par in SSP and DAP treatments
and was significantly higher in comparison to NP and reverse was true in case of A-value of the soil. Results on equivalent
ratio showed that SSP and DAP are equally efficient, whereas, 1 kg P as SSP was equivalent to 7.47 kg P as NP. In general,
efficacy of phosphatic fertilizers for cotton crop in vertisol was found to be in order of SSP>DAP>NP.
Authors:M. Bernardi, E. Leite, E. Longo, M. Conceiçăo, and A. Souza
The color efficiency of ceramic glaze blue pigments obtained by the Pechini method was presented in this work. The fired pigments
and enameled samples were characterized by thermogravimetry (TG) and differential thermal analysis (DTA), XRD, UV-VIS-NIR
spectroscopy and CIE-L*a*b* color-measurements. The pigments obtained by the Pechini method present a better solubility in
the molten glazes than the pigments obtained by the mechanical mixture of the precursor oxides.
Authors:R. Candeia, J. Freitas, M. Souza, Marta Conceição, Iêda Santos, L. Soledade, and A. Souza
The most feasible alternative among fuels derived from biomass seems
to be the biodiesel, having the required characteristics for a total or partial
substitution of diesel oil. Therefore, the aim of this work is to evaluate
the thermal and rheological behavior of the blends of diesel with the methanol
biodiesel obtained from soybean oil, using B5, B15 and B25 blends. All thermogravimetric
curves exhibited one overlapping mass loss step in the 35–280C
temperature range at air atmosphere and one step between 37–265C
in nitrogen. The rheological study showed a Newtonian behavior (n=1) for all blends.
Authors:A. Garrido Pedrosa, M. Souza, S. Lima, Dulce Melo, A. Souza, and A. Araújo
bifunctional catalysts were synthesized using impregnation and polymeric precursor
methods. After the synthesis process the samples were calcined at 600, 700
and 800C and characterized by X-ray diffraction, nitrogen adsorption
and temperature programmed reduction study by thermogravimetry. DTG-TPR profiles
showed between three and five reduction events at different temperatures attributed
to platinum reduction and to different stages of tungsten species reduction.
A comparative study of the synthesis method influence on the DTG-TPR curves
Authors:M. Conceição, A. Melo, N. Narain, I. Santos, and A. Souza
The thermogravimetric procedures applied to quality control of foods attain the global analysis of quality of the product,
through the determination of quality parameters and the thermal stability of products. The kinetic parameters such as order
of reaction, apparent activation energy, pre-exponential factors and the thermal decomposition rate constant were determined
for the samples of corn and its derivatives by applying isothermal thermogravimetry, utilizing the Arrhenius law. This method
presented excellent results as verified with the coherence and data adjustment. The rate constant values showed the expected
performance from the chemical point of view.
Authors:Gerlania Silva, A. Souza, J. Botelho, M. Silva, and T. Silva
isomer obtained by hydrolysis of cis-bixin and isolated by solvent extraction
from annatto seeds. The thermal decomposition data of the cis-norbixin samples
were analyzed by thermogravimetric analysis at different heating rates in
the 25–900C temperature range. DSC curves showed that thermal decomposition
reactions for cis-norbixin occurred in the solid phase. The kinetic parameters,
such as activation energy and pre-exponential factor were determined using
integral and approximate methods: Coats–Redfern, Madhusudanan, Horowitz–Metzger
and Van Krevelen. F1 mechanism describes well the first stage of the thermal
Authors:A. Silva, M. Souza, J. Aquino, V. Fernandes, and A. Araújo
The coke removal of HZSM-12 zeolite deactivated in the reaction of n-heptane cracking was studied by thermogravimetry using
two multiple heating rate integral kinetics models proposed by Ozawa-Flynn-Wall and Vyazovkin to obtain the activation energy
of process of thermoxidation of coke. The results obtained by both models presented excellent accordance with the related
Authors:E. Medeiros, R. Tocchetto, L. Carvalho, M. Conceição, and A. Souza
In this work, the influence of attapulgite concentration on the nucleating efficiency of isotactic polypropylene (iPP) and
on the kinetics of non-isothermal crystallization were ascertained.The study was conducted by DSC. The nucleating efficiency
was determined according to the procedure described by Fillon and the kinetics of non-isothermal crystallization was determined
using Ozawa's method using cooling rates of 2, 5 and 10C min−1.Our results indicate that both the relative crystallinity and the crystallization temperature increase with filler content
and that a maximum occurs at 2% mass/mass filler content. Both parameters decrease with increasing cooling rates. The Ozawa's
exponent tended to increase with temperature and filler content.