Authors:Maria Gonçalves, Méri Vieira, Wildson Cerqueira, and Ana Teixeira
The purpose of this work was to employ the differential thermal analysis technique (DTA) to compare variations in the collapse
energy of the Y zeolite crystalline structure in a fresh sample and in the sample after temperature treatment and impregnated
with 3,000 ppm of vanadium and nickel. A small exothermic signal in the DTA curve at 950–1,150 °C indicated the collapse of
the crystalline structure. The areas of the exothermic signals in the DTA curves of the samples indicated a 20% reduction
in the exothermic area peak of sample treated 600 °C for 3 h and 25% reduction in same peak in the metal impregnated Y zeolite.
These results were compared with X-ray data leading to the conclusion that metal impregnation affects the Y zeolite crystalline
structure and that the DTA technique is a potentially useful tool for measuring the integrity of Y zeolite in catalysts.
Authors:Maria Gonçalves, Deusa da Mota Pinto, Ana Teixeira, and M. Teixeira
Dynamic kinetic analyses were performed on different Brazilian petroleum fractions by thermogravimetry. The data were treated
by a multiple heating rate methodology. The apparent activation energies for the light and middle fractions within the range
of 62–74 kJ mol−1 and for heavy distillation residues were within the range of 80–100 kJ mol−1 at lower conversions and 100–240 kJ mol−1 at higher conversions. The kinetic study can be a criterion for tells apart the main phenomena involved in the thermal behavior
of the refinery feedstock.
Authors:Maria Gonçalves, Joyce Barreto, Wildson Cerqueira, and Ana Teixeira
This work evaluates the effect of the FCC catalyst components—Y zeolite, kaolin and alumina—on the formation of coke during
the cracking of heavy residue (HR) of petroleum. The Y zeolite, kaolin and alumina were mixed with a HR at a ratio of approximately
1:4. The effect was studied using dynamic thermogravimetry at a heating rate of 50 K min−1, with N2 (between 35 and 700 °C) and air (in the 700–1,000 °C temperature range). The HR analyzed in these conditions formed 8.1%
of coke. All the mixtures presented larger coke formation than that observed in pure HR. The Y zeolite presented fourfold
larger coke formation, while kaolin and alumina showed twofold higher formation than pure HR. The major focus of this study
was to verify the sensitivity of the TG technique in providing information about coke formation in the fluid catalytic process
Authors:Maria Gonçalves, Meri Vieira, Deusa Mota, Wildson Cerqueira, and Ana Teixeira
The purpose of this work was to employ the differential thermal analysis (DTA) technique to compare variations in the collapse
energy of the zeolite Y crystalline structure in a fresh catalyst and in the same catalyst impregnated with nickel and vanadium.
A small exothermic signal in the DTA curve at 950–1150 °C indicated the collapse of the crystalline structure. The areas of
the exothermic signals in the DTA curves of the two samples indicated a reduction in the curve of the metal impregnated catalyst.
These results were compared with X-ray data, leading to the conclusion that metal impregnation affects the zeolite Y crystalline
structure and that the DTA technique is a potentially useful tool for measuring the integrity of zeolite Y in catalysts.
Authors:Maria Luisa A. Gonçalves, Deusa A. Pinto da Mota, Ana Maria R. F. Teixeira, and M. A. G. Teixeira
Summary Thermogravimetry (TG) is a potential tool to evaluate petroleum distillation residues, obtained in the crude oil distillation. Analyses were done at different heating rates, mass samples and gas flow rates. No differences were observed in the yields of the products formed during the pyrolysis at different analytical conditions. Linear correlation was found between the results of the TG and the standard methods for the prediction of the light fraction rates given by the pyrolysis.
Authors:Maria Ribeiro da Silva, N. Araújo, A. Silva, L. da Silva, N. Barros, J. Gonçalves, and M. Ribeiro da Silva
The standard (p0=0.1
MPa) molar enthalpies of formation, at T=298.15
K, in the gaseous phase, for three tetradentate Schiff bases involving a N2O2
(H2salch), N,N’-bis(acetylacetone)cyclohexanediimine (H2acacch)
(H2bzacch), were determined from their enthalpies of
combustion and sublimation, obtained by static bomb calorimetry in oxygen
and by the Knudsen effusion technique, respectively. The results are compared
with identical parameters for related compounds previously studied, resulting
from the condensation of salicylaldehyde or β-diketone with aliphatic
Authors:Maria Luisa A. Gonçalves, D. A. Ribeiro, Deusa Angélica P. Da Mota, Ana Maria R. F. Teixeira, and M. A. G. Teixeira
Summary Thermogravimetry (TG) was applied to evaluate the thermal behavior of five refinery atmospheric distillation residues (ATR) obtained from different Brazilian crude oils. The asphaltenes were extracted of each sample and their influence on coke formation was studied. It was observed that they have a great contribution on carbonaceous residues formation during pyrolysis and that the heavier the ATR sample, the higher is the contribution of other heavy components present in ATR samples.
Authors:Tábata Maués, Táya Figueiredo de Oliveira, Kênia Balbi El-Jaick, Agnes Marie Sá Figueiredo, Maria De Lourdes Gonçalves Ferreira, and Ana Maria Reis Ferreira
TP53 and PGAM1 genes play a key role in glycolysis which is an essential metabolic pathway of cancer cells for obtaining energy. The purpose of this work was to evaluate PGAM1 and TP53 mRNA expressions in canine mammary carcinomas (CMC) and to correlate them with animal data and tumour histological features. None of the nine samples analysed revealed PGAM1 DNA sequence variations. PGAM1 and TP53 RNA expressions from 21 CMC were analysed using a one-step reverse transcription-PCR kit and its platform system. Most CMC samples had low levels of PGAM1 mRNA (71.5%) and normal expression of TP53 mRNA (95.2%). Our results suggest a different feature of the Warburg effect on canine mammary cancer cells compared to human cells.