Authors:F. Santos de Souza, A. Gomes Barreto, and R. Macêdo
The present work proposes evaluation of the gelatinization processes of starch by means of DSC coupled with a photovisual
system. The use of DSC, TG and DTA for a fast and efficient evaluation of the starch is suggested. The DSC curves of starch
gels with water contents of 20, 30, 40 and 50% (mass/v) exhibited different phase transitions, corresponding to the gelatinization
processes at the different water contents for the different lots. The DSC-photovisual system confirmed calorimetric behaviour
differences between the starch lots studied.
Authors:A. Moitinho, E. Ionashiro, G. de Souza, and F. Fertonani
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.
Authors:A. de Oliveira, J. Ferreira, Márcia Silva, Soraia de Souza, F. Vieira, E. Longo, A. Souza, and Iêda Santos
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.
Authors:Ana Santos, I. Basílio, F. de Souza, A. Medeiros, Márcia Pinto, D. de Santana, and R. Macêdo
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.
Authors:Soraia de Souza, Mary Alves, A. de Oliveira, E. Longo, F. Ticiano Gomes Vieira, Rodinei Gomes, L. Soledade, A. de Souza, and Iêda Garcia dos Santos
In this work, the synthesis of Nd-doped SrSnO3 by the polymeric precursor method, with calcination between 250 and 700 °C is reported. The powder precursors were characterized
by TG/DTA and high temperature X-ray diffraction (HTXRD). After heat treatment, the material was characterized by XRD and
infrared spectroscopy. Ester and carbonate amounts were strictly related to Nd-doping. According to XRD patterns, the orthorhombic
perovskite was obtained at 700 °C for SrSnO3 and SrSn0.99Nd0.01O3. For Sr0.99Nd0.01SnO3, the kinetics displayed an important hole in the crystallization process, as no peak was observed in HTXRD up to 700 °C,
while a XRD patterns showed a crystalline material after calcination at 250 °C.
Authors:Hiléia de Souza, E. Sousa, M. Paiva, F. Borges, D. Melo, and H. Scatena
The reason of comparing thermal behaviour and kinetics of some nickel compounds, is justified by the influence of anion on
it, besides supplying information on the stability of the salts. In this work, Ni(TMS)2·6H2O, Ni(TFA)2·3H2O and Ni(Ac)2·2H2O, were synthesized and characterized by microanalysis, atomic absorption molar, conductance and thermal analysis. Thermogravimetric
curves indicate that the decomposition of the salts occurs in the range 295–1169 K and the NiO is the final residue. Non-isothermal
kinetic evaluation from thermogravimetric data was used to determine energies of activation and pre-exponential factors.
Authors:I. Pastre, I. do Nascimento Oliveira, A. Moitinho, G. de Souza, E. Ionashiro, and F. Fertonani
The composite montmorillonite-8-hydroxyquinoline (Swy-1-8-HQ) was prepared by two different processes and studied by using
thermogravimetric analysis (TG/DTG and DSC), as well as helpful techniques as fluorescence in the UV-visible region and X-ray
diffraction. The composites developed fluorescent appearance, however with quantum poor efficiency and they exhibited distinct
TG and DSC thermal behavior. The fluorescence data of spectra associated to the TG/DT curves allowed to suggest that the 8-HQ
was present in the composites in two different circumstances: 1 - intercalated in the interlayer spaces (Swy-1-8-HQ2), rigidly
associated to the substrate feasible as a monolayer with the aromatic rings parallel to the silica layer; and/or, 2 - adsorbed
on the surface (Swy-1-8-HQ1), either as a bilayer formation or tilting of the molecules to the silicate layer sheet. All results
confirmed above are in agreement with X-ray diffraction patterns, once the interlayer space increases when 8-HQ is incorporated.
The experimental results confirm the formation of the composites in agreement with the method used in the preparation.
Authors:Isabel Cherici Camargo, Roberta Barreiros De Souza, Suzana Fátima Paccola Mesquita, L. Chuffa, and F. Frei
The study was conducted to analyze the histology of the ovaries of adults rats treated with steroids, and submitted or not to physical effort. The control group consisted of females submitted to physical effort and sedentary females, both of which received a physiological solution of 0.9% saline. Treated females, sedentary or not, received 6 mg/kg of body weight of nandrolone decanoate. The steroid and physiological solution were administered intraperitoneally, with a single injection per week for 4 consecutive weeks. The applied physical effort was swimming (20 minutes daily, 5 days/week, for the 4 weeks of treatment). Serial sections (5 μm) of ovaries were prepared for histological evaluation and follicular score. The weight of ovaries and hypophysis, the number of antral and atretic follicles, and the area of corpus luteum were all affected by the steroids. In the ovaries of the control groups, well-developed corpus luteum was observed. In the treated groups, the cortical stroma was occupied by ovarian interstitial tissue. The females treated with steroids presented estral acyclicity. The use of nandrolone decanoate, whether associated with physical effort or not, affected the morphological pattern of the ovaries.