Authors:J. Gonçalves, R. Toledo Filho, and E. Fairbairn
This paper reports an experimental study on the magnesium sulphate resistance of mortar specimens incorporating 0, 10 and
20% of metakaolin (MK). The evidence of the attack was evaluated through the content of calcium hydroxide (portlandite) and
formation of magnesium hydroxide (brucite) by thermal analysis (thermogravimetric and derivative thermogravimetric analysis).
The mechanical degradation of the mortar specimens was evaluated through splitting tensile tests after 200 days of exposition
to the magnesium solution. The addition of metakaolin resulted in a reduction in the content of calcium hydroxide and in a
smaller formation of brucite in comparison with reference mixture. A tensile strength loss of about 7% was observed for the
metakaolin mortars submitted to the magnesium solution attack for 200 days.
The study of fossil materials is very important in the geological and biological researches. They can involve ancient past,
evolution or extinction of species, oil prospecting and the understanding of different areas such as: paleoclimate, paleoecology,
paleogeography, in addition of climate, environmental changes and life. Araripe Geopark is located in the south area of the
Ceará state in the Northeast of Brazil and it provides a general overview of the Earth’s History. In this study the vertebral
column extinct fish, Cladocyclus ferox and its nodule from Santana Formation, Northeast of Brazil, calcite and apatite minerals, and vertebral column of recent
fish, Opisthonema oglinum were investigated by means of thermal analysis. TG/DTG and DTA curves showed decomposition processes, suggesting water evolution,
calcium carbonate and phosphate decomposition and thermal transitions indicated that fossilization processes of fish, carbonaceous
material involved the fossil after its death and the organic substance was replaced by inorganic compounds.
This work proposes thermal characterization as analytical methodology for the identification and purity assay of warifteine,
an alkaloid in Cissampelos sympodialis Eichl. Thermal and kinetic parameters were determined by means of TG and DSC photovisual studies. The TG results showed that
the decomposition of warifteine in air and nitrogen atmospheres proceeds in three and four steps, respectively. The TG data
allowed calculation of the kinetic parameters of warifteine. The activation energy values obtained by different methods displayed
a good correlation. With the DSC photovisual system applied it is possible to detect the impurity level in warifteine after
Authors:R. Parise Filho, A. Araújo, M. Santos Filho, J. Matos, M. Silveira, and C. Brandt
Oxamniquine (OXA) is a schistosomicide agent that causes some adverse effects in central nervous system. Intending to improve
OXA therapeutic properties, a polymeric prodrug was designed. Currently, there is an increasing interest of thermal analytical
techniques in the pharmaceutical area, so differential thermal analysis (DTA) and thermogravimetry (TG) were carried out to
evaluate the thermal behavior of OXA, polymethacrylic acid (PMA), [poly(methacrylic-co-oxamniquine methacrylate)acid] (PMOXA)
and physical mixture (OXA+PMA). The thermoanalytical profile of the physical mixture showed characteristic events of the thermal
decomposition of OXA and PMA. Distinctly, PMOXA DTA curve did not show an endothermic peak at 148.5C indicating that the
drug was incorporated into the polymeric system. These results were corroborated by the IR spectroscopy and X-ray diffraction
Authors:R. Cunha e Silva, E. Almeida, E. Valencia, and V. Filho
Total reflection X-ray fluorescence (TXRF) was used to determine simultaneously the concentration of Cu, Fe and Zn in seven
sugar-cane spirit samples (“aguardente”), a processed alcoholic beverage made from the fermentation and distillation of sugar-cane
juice. The limits of detection ranged from 35 to 8 ng.ml-1 for V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As and Se. Excluding Fe, Cu and Zn, the concentrations were below their limits. Two samples
showed Cu concentrations higher than the value allowed by Brazilian legislation (5 µg.ml-1), and concerning Fe and Zn, no sample were above the limits permitted by WHO for drinking water (2 and 3 µg.ml-1, respectively).
Authors:R. Filho, P. Franco, E. Conceição, and M. Leles
A formulation of nifedipine tablets was prepared in the present research. The tablets were conditioned in amber-colored glass
containers and placed in a climatized room at 40°C and relative humidity of 75% for 180 days. Differential scanning calorimetry
(DSC) and thermogravimetry (TG) were used in order to evaluate the thermal properties of nifedipine, the excipients and two
well-known nifedipine degradation products. The results demonstrated that there is no evidence on the interaction between
nifedipine and excipients, or degradation products.
Authors:R. Filho, P. Franco, E. Conceição, and M. Leles
A new formulation of nifedipine tablets was prepared. The tablets were conditioned in amber-colored glass containers and placed
in a climatized room at 40 °C and relative humidity of 75% for 180 days. Differential scanning calorimetry (DSC) and Thermogravimetry
(TG) were used in order to evaluate the thermal properties of nifedipine, the excipients and two well-known nifedipine degradation
products. There is no evidence of interaction between nifedipine and excipients or degradation products. High performance
liquid chromatography (HPLC) was used in the dosage of nifedipine tablets before and after acclimatized exposure. Results
show that DSC and TG offer important data for a more detailed assessment of the stability of a pharmaceutical formulation.
Authors:A. Vasconcelos, M. Dantas, M. Filho, R. Rosenhaim, E. Cavalcanti, N. Antoniosi Filho, F. Sinfrônio, I. Santos, and A. Souza
The influence of drying processes in the biodiesel oxidation was investigated by means of the oxidative induction time obtained
from differential scanning calorimetry data. For this purpose, corn biodiesel was dried by different methods including: chemical
(anhydrous sodium sulfate) and thermal (induction heating, heating under vacuum and with microwave irradiation). The drying
efficiency was evaluated by monitoring IR absorption in the 3,500–3,200 cm−1 range and by the AOCS Bc 2-49 method. In general, the oxidative induction times increased inversely to the heating degree,
except that of microwave irradiation, which was selective to water evaporation and caused low impact over the unsaturation
of biodiesel. The DSC technique was shown to be a powerful tool to evaluate with high level of differentiation the influence
of the drying process on the oxidative stability of biodiesel.
Authors:R. Leite, W. Jacob-Filho, M. Saiki, L. Grinberg, and R. Ferretti
Neutron activation analysis was applied to assess trace element concentrations in brain tissues from normal (n = 21) and demented individuals (n = 21) of both genders aged more than 50 years. Concentrations of the elements Br, Fe, K, Na, Rb, Se and Zn were determined.
Comparisons were made between the results obtained for the hippocampus and frontal cortex tissues, as well as, those obtained
in brains of normal and demented individuals. Certified reference materials, NIST 1566b Oyster Tissue and NIST 1577b Bovine
Liver were analyzed for quality of the analytical results.