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Abstract  

Hair analysis presents a lot of advantages compared to the analysis of biological fluids or tissues. Hair of employers from the National (Brazilian) Nuclear Energy Commission (CNEN) was analyzed and compared with a control group. Samples were heated at 90°C with nitric acid, and diluted. Aliquot of these solutions was analyzed in ICP-MS. The concentration of U, Th, Pb and Zn were determined. Student t-test showed that there is no significant difference among the groups for all analyzed elements. The results demonstrated that men had more Pb than women. For Zn, the results showed that the levels are within the “normal” range, except for a woman that had her hair painted.

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Abstract  

Poly(3-hydroxybutyrate), PHB has been structurally modified through reaction with maleic anhydride, MA. Transesterification reaction was carried out fixing the PHB and MA and besides time and temperature the concentration of the triethylamine (used as catalyst) was changed. Glass transition, melting and crystallization temperature obtained from DSC curves and thermal degradation temperatures obtained from TG traces were used to evaluate the influence of the reaction conditions on the modification of PHB according to factorial design. On the base of the results the optimum conditions are to perform the PHB modification reaction with MA reaction at 110C for 1 h with 5% v/v triethylamine.

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Abstract  

Solid-state M-EDTA chelates, where M represents the divalent ions Mg(II), Ca(II), Sr(II) or Ba(II) and EDTA is ethylenediaminetetraacetate anion, were synthesized. Thermogravimetry, derivative thermogravimetry (TG, DTG), differential scanning calorimetry (DSC) and X-ray diffraction powder patterns have been used to characterize and to study the thermal behaviour of these chelates. The results provided information concerning the stoichiometry, crystallinity, thermal stability and thermal decomposition.

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Abstract  

The thermal degradation process of mineral base lubricating oils was studied in this work by means of thermal, spectroscopic and rheologic analysis. The lubricating oils were degraded at temperatures varying from 150 to 210C, and for degradation times from 1 to 48 h. After the degradation, the lubricating oils were characterized by X-ray fluorescence, IR and NMR spectroscopies, rheological properties and thermal analyses (TG/DSC). The spectroscopic analyses determined the oxidation reaction products. TG curves indicate that the thermal stability of lubricating oils is below 161C. TG curves in air present three mass loss stages, whereas in nitrogen there are only two mass loss steps. DSC analyses in air indicate two highly exothermic peaks related to hydrocarbon oxidation and combustion processes, while in nitrogen only two endothermic peaks were observed. The decrease in the degradation temperature led to a decrease of the lubricant viscosity.

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In this perspective article, the use of continuous flow synthesis to prepare advanced pharmaceutical intermediates in developing economies is highlighted. Case studies are presented to suggest that cost effective local manufacture of life saving drugs, may potentially be implemented to facilitate better access to drugs to the underprivileged.

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Solid state reactions in the platinum–mercury system

Thermogravimetry and differential scanning calorimetry

Journal of Thermal Analysis and Calorimetry
Authors: G. Souza, I. Pastre, A. Benedetti, C. Ribeiro, and F. Fertonani

Abstract  

Thermogravimetry, Differential Scanning Calorimetry and other analytical techniques (Energy Dispersive X-ray Analysis; Scanning Electron Microscopy; Mapping Surface; X-ray Diffraction; Inductively Coupled Plasma Atomic Emission Spectroscopy and Cold Vapor Generation Atomic Absorption Spectroscopy) have been used to study the reaction of mercury with platinum foils. The results suggest that, when heated, the electrodeposited Hg film reacts with Pt to form intermetallic compounds each having a different stability, indicated by at least three mass loss steps. Intermetallic compounds such as PtHg4, PtHg and PtHg2 were characterized by XRD. These intermetallic compounds were the main products formed on the surface of the samples after partial removal of bulk mercury via thermal desorption. The Pt(Hg) solid solution formation caused great surface instability, attributed to the atomic size factor between Hg and Pt, facilitating the acid solution’s attack to the surface.

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Abstract  

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.

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Journal of Thermal Analysis and Calorimetry
Authors: F. Vieira, Soraia Souza, A. Oliveira, S. Lima, E. Longo, C. Paskocimas, L. Soledade, A. Souza, and Iêda Santos

Abstract  

In this study undoped and Cr, Sb or Mo doped TiO2 were synthesized by polymeric precursor method and characterized by X-ray diffraction, UV–VIS spectroscopy, infrared spectroscopy and thermogravimetry (TG). The TG curves showed a continuous mass loss assigned to the hydroxyl elimination and Cr6+ reduction. Doped TiO2 samples showed a higher mass loss assigned to water and gas elimination at lower temperatures. In these doped materials a decrease in the anatase–rutile phase transition temperature was observed. After calcination at 1,000 °C, rutile was obtained as a single phase material without the presence of Cr6+.

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Journal of Thermal Analysis and Calorimetry
Authors: A. de Oliveira, J. Ferreira, Márcia Silva, Soraia de Souza, F. Vieira, E. Longo, A. Souza, and Iêda Santos

Abstract  

NiWO4 and ZnWO4 were synthesized by the polymeric precursor method at low temperatures with zinc or nickel carbonate as secondary phase. The materials were characterized by thermal analysis (TG/DTA), infrared spectroscopy, UV–Vis spectroscopy and X-ray diffraction. NiWO4 was crystalline after calcination at 350 °C/12 h while ZnWO4 only crystallized after calcination at 400 °C for 2 h. Thermal decomposition of the powder precursor of NiWO4 heat treated for 12 h had one exothermic transition, while the precursor heat treated for 24 h had one more step between 600 and 800 °C with a small mass gain. Powder precursor of ZnWO4 presented three exothermic transitions, with peak temperatures and mass losses higher than NiWO4 has indicating that nickel made carbon elimination easier.

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Journal of Thermal Analysis and Calorimetry
Authors: E. F. S. M. Ramalho, A. R. Albuquerque, A. L. Souza, A. K. Barro, A. S. Maia, I. M. G. Santos, and A. G. Souza

Abstract

The poultry fat methylic (BMF) and ethylic (BEF) biodiesels were synthesized through transesterification by homogeneous basic catalysis. The chromatographic analyses showed the palmitic, stearic, oleic, and linoleic esters as majority components. Owing to its considerable amount of polyunsaturated fat acids, poultry fat usually leads to a biodiesel with low oxidative stability. In this study, the oxidation of their ethylic and methylic biodiesels was evaluated by Rancimat, PDSC, and PetroOxy. The OSI (Rancimat) was of 0.47 and 0.40 h for the ethylic and methylic biodiesel, respectively. In PDSC, both fuels presented an OT of about 120–123 °C. PetroOxy analysis indicated an OxyStab of 11 min for BEF and higher than 11 min for BMF. There was no correspondence among the oxidative stabilities of the employed techniques [OT(BEF) ≈ OT(BMF), OSI(BEF) > OSI(BMF), and OxyStab(BEF) < OxyStab(BMF)]. The discussion of these results was based on the indicator measured by each technique: enthalpic events are observed by PDSC; conductivity of volatile secondary oxidation products is measured by Rancimat; reduction of the oxygen pressure is determined by PetroOxy. This discussion showed that these different indicators do not reflect the same stage of the oxidative process as energy is release at the beginning of the propagation step, oxygen pressure decreases during the propagation step, and oxidation products are formed during the termination step.

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