Authors:I. Santos, F. Waerenborgh, and L. Patricio
Optimal conditions for coupling sheep anti-T3 IgG to a solid phase are presented. We found that the optimal activation of microcrystalline cellulose was achieved with 0.15M 1,1-carbonyldiimidazol (CDI) in acetone. We also found that using a 25 mg/cm3 anti-T3 IgG solution, in barbitone buffer 0.05M, pH 8.0, we could get a reasonable yield of coupling and a remaining solution of anti-T3 IgG (first supernatant) with a suitable concentration (10 mg/cm3) for another coupling. The solid phase anti-T3 obtained in these two couplings present similar characteristics which make possible their use in a total T3 RIA.
Authors:C. Santos, B. Capistrano, F. Vieira, M. Santos, S. Lima, E. Longo, C. Paskocimas, A. Souza, L. Soledade, and I. Santos
In this work, spinels with the general formula Zn2−xCoxTiO4 were synthesized by the polymeric precursor method and thermally treated at 1,000 °C. The powder precursors were characterized
by TG/DTA. A decrease in the DTA peak temperature with the amount of zinc was observed. After the thermal treatment, the characterizations
were performed by XRD, IR, colorimetry and UV/VIS spectroscopy. The XRD patterns of all the samples showed the presence of
the spinel phase. Infrared spectroscopy showed the presence of ester complexes for Zn2TiO4 after thermal treatment at 500 °C, which disappeared after cobalt addition, indicating that organic material elimination
Authors:N. Santos, J. Santos, F. Sinfrônio, T. Bicudo, I. Santos, N. Antoniosi Filho, V. Fernandes, and A. Souza
The babassu (Orbignya Phalerata Mart.) biodiesel has lauric esters as main constituents, resulting in high oxidative stability and low cloud and freezing
points. In order to reduce these side effects, the saturated ethyl esters content was reduced by means of winterization process.
The TMDSC and PDSC techniques were used to verify the thermal and oxidative stabilities of the ethyl babassu biodiesel. During
the heating stage, the winterized solid phase of ethyl esters presented an endothermic transition associated to the solidification
process. This behavior was not observed for the liquid winterized FAEE, confirming the efficiency of the winterization process.
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:J. Santos, I. Santos, M. Conceiçăo, S. Porto, M. Trindade, A. Souza, S. Prasad, V. Fernandes, and A. Araújo
Thermoanalytical, kinetic and rheological parameters of commercial edible oils were evaluated. The thermal decomposition of
the oils occurred in three steps, due to polyunsaturated, monounsaturated and saturated fatty acids decomposition, respectively.
According to the temperature of the beginning of the decomposition, the following stability order was observed: corn (A)>corn>sunflower
(A)>rice>soybean>rapeseed (A)>olive>rapeseed>sunflower (A - artificial antioxidants). Kinetic parameters were obtained using
Coats-Redfern and Madhusudanan methods and presented good correlation. According to the activation energy of the first thermal
decomposition event, obtained of Coats-Redfern' method, the following stability order is proposed: sunflower>corn>rice>soybean>rapeseed>olive.
In relation to rheological properties, a Newtonian behavior was observed and no degradation occurred in the temperature range
Authors:A. Souza, H. Danta, M. Silva, I. Santos, V. Fernandes, F. Sinfrônio, L. Teixeira, and Cs. Novák
The biodiesel obtained by transesterification by reaction between ester and an alcohol in the presence of catalyst. The purpose
of this work is to evaluate the thermal and kinetic behavior of the methanol biodiesel derived from cotton oil. The quality
analysis was done by gas chromatography and proton nuclear magnetic resonance spectrometry (1H NMR) in order to examine if the product meets with the requirements of the European Standard EN 1403. The thermogravimetric
profile of the cotton biodiesel indicated that the decomposition steps are associated to the volatilization and/or decomposition
of the methyl esters. Kinetic data was also obtained by thermal analysis.
Authors:F. Albuquerque, B. Parente, S. Lima, C. Paskocimas, E. Longo, A. Souza, I. Santos, and V. Fernandes
The use of clays for ceramic filter processing may reduce its cost, leading to different applications, as water treatment.
In this work, a low cost tile clay mixed with kaolin, for use in ceramic filters, were evaluated. Mineralogical and thermal
changes occurring during sintering were characterized by differential thermal analysis, thermogravimetry, thermomechanical
analysis and X-ray diffraction. An increase in the initial melting temperature of samples due to kaolin addition was observed.
Mullite formation in kaolin was observed by DTA and in other samples by XRD. TMA analysis permitted the observation of pre-sintering
step, around 850C. This step is difficult to observe in other types of analysis.