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- Author or Editor: I. Santos x
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Abstract
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.
Abstract
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.
Abstract
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 was favored.
Abstract
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.
Abstract
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 studied.
Abstract
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.
Abstract
Thermal analysis is an essential analytical tool in development of new formulations as well as to study the interaction between drugs and excipients. This work aims to investigate the possible interactions between metformin and excipients as microcrystalline cellulose (Microcel MC101®), starch sodium glycolate (Explosol®), sodium croscarmellose (Explosel®), PVP K30, magnesium stearate, starch and lactose, usually employed in pharmaceutical products. TG, DSC and DTA techniques were used for the thermal characterization to track if the thermal properties of the drug substance were modified in the mixture. Disregard of the starch and lactose systems, no changes in thermal behavior of mixtures were found. Thermogravimetric studies (TG) of metformin and its binary mixtures showed different thermal behavior.
Abstract
The kinetics of thermal decomposition of solid In(S2CNR2)3 complexes, (R=CH3, C2H5, n-C3H7,i-C3H7, n-C4H9 and i-C4H9), has been studied using isothermal and non-isothermal thermogravimetry. Superimposed TG/DTG/DSC curves show that thermal decomposition reactions occur in the liquid phase, except for the In(S2CNMe2)3 and In(S2CNPri 2)3 compounds.
