Composites of poly(vinyl pyrrolidone)/hydroxyapatite (PVP/HA), at variable proportions (100/0; 80/20; 50/50; 20/80 wt%) were
prepared and characterized by Fourier transformer-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential
scanning calorimetry (DSC), and thermogravimetry/differential thermogravimetry (TG/DTG). PVP carbonyl stretching was slightly
shifted to lower frequency in composites indicating the formation of hydrogen bonding with HA hydroxyl groups. At the first
cycle of heating, the calorimetric curves revealed a broad peak the intensity of which was reduced insofar as the amount of
PVP decreased in the composites. This peak was attributed to the PVP enthalpy relaxation. According to the TG/DTG curves,
PVP degraded into two steps sharply perceivable in the composites. The first decay was ascribed to the release of the pyrrolidone
pendant groups and the following one concerned the burning of the hydrocarbon chains. The HA molecules seem to exert a catalytic
action on the PVP degradation.
The137Cs radionuclide dispersion in the marine environment through the compartmental model is reported. The model simulates the surface water contamination caused by routine or accidental radionuclide releases. For the simulation the OCEAN program was applied in the North Sea, near to Sellafield and adjacent areas, based on published transfer coefficient data. The results are in good agreement with the literature and the model developed can be applied to the brazilian coastal regions.
Authors:C. R. Dos Santos, R. S. Rodrigues, C. S. Silva, and E. S. Nascimento
A simple, selective and sensitive method was developed based on electrothermal atomic absorption spectrometry using Zeeman
correction for quantitation of lead, in 100 ml of whole blood sample, as biological indicator for occupational exposure. Confidence
parameters and stability of samples were considered. Ashing and atomization temperatures, considered critical, were 700 °C
and 1,700 °C, respectively. The levels found during the validation process showed good sensitivity linearity, recovery, precision
and accuracy. The stability results presented levels remaining constant for a 15 months period. The variations were not higher
than 15% when comparing concentrations in zero time to those obtained after storage period.
Authors:S. Zeisler, R. Pavan, J. Orzechowski, R. Langlois, S. Rodrigue, and J. van Lier
At energies £15 MeV, 64Cu is most readily produced using the 64Ni(p,n)64Cu reaction. Space restrictions in the TR-PET target selector required a target system of compact design that would still allow the quick and easy removal of the irradiated target. The target consists of a 64Ni-plated rhodium disc held in place by a threaded cooling assembly. For removal, the cooling block is rotated slightly, allowing the disc to fall into a shielding container. The nickel is dissolved and the 64Cu separated by anion exchange or electrochemical deposition. Yields of up to 330 mCi of radiochemically pure 64Cu have been obtained.
Authors:D. Cardoso, R. Rodrigues, V. Toledo, T. Moraes-Santos, V. Cardoso, and E. Nunan
F(ab’)2 is the fragment involved in the immunotherapy for scorpion stings and it would be convenient to label it with 99mTc for organ distribution and pharmacokinetics studies. The aim of the present study was to label scorpion antivenom F(ab’)2 with 99mTc keeping its biological activity, integrity and stability. High labeling yield was obtained using stannous chloride and
sodium borohydride. Stability, immunoreactivity and integrity of 99mTc-F(ab’)2 was preserved. It was not observed any difference between potencies of unlabeled and labeled antivenom. 99mTc-F(ab’)2 can be a useful tool for use in biodistribution and pharmacokinetics studies on the evaluation of the efficacy of the antivenom
against scorpion envenomation.
Authors:Gabrielle Souza Rocha, A. Fonseca, Michelle Rodrigues, F. Dantas, A. Caldeira-de-Araujo, and R. Santos
The aim of this work was to evaluate, by comet assay, the possible inducing of DNA lesions in peripheral blood mononuclear cells of rats subjected to acute or chronic food deprivation. Wistar male rats were subjected to 72 h of partial (50%), or total acute food deprivation, and then allowed to recover for different time periods (24, 48 and 72 h). In other experiments, comet scores were determined in peripheral blood mononuclear cells of rats subjected to chronic food deprivation (25% and 50%) for 50 days. Blood aliquots were obtained before, during and after food deprivation. Comet assay was carried out, the comet units photographed and scored (class 0 up to 3). Acute and chronic food-deprived rats presented peripheral blood mononuclear cells with DNA lesions (comet classes 1, 2 and 3) and a significant increase (
< 0.05) in the number of comet units compared with its basal level. The increase was proportional to acute food deprivation time, but after being taken off, it progressively returned to basal level after 48 h (partial group) or 72 h (total group). Chronic food-deprived rats presented a progressive increase of comet score up to 5 days, and a decrease thereafter to reach a basal level. Possible mechanisms of DNA lesions are discussed.
Authors:G. F. Barbosa, F. L. A. Machado, A. R. Rodrigues, and W. M. Azevedo
Magnetic thermogravimetric analysis (TGM) was used to investigate the influence of the milling time (tmill) in the Curie temperature (TC) of nanocrystalline powders and of a melt-spun amorphous ribbon with composition Fe56Co7Ni7Zr10B20. The TGM analysis was carried in a continuous flow of 99.99% pure argon from room temperature up to 1250 K. A magnetic field of 100 Oe was applied throughout the measurements. Nanopowders of Fe56Co7Ni7Zr10B20 were produced by mechanical alloying the samples in an argon atmosphere for milling times ranging from 1 to 100 h. The samples were characterized by X-ray diffraction and by scanning electron microscopy. The average particle size decreased from 45.4 nm for a powder milled for 1 h to 5 nm after being milled for 100 h. Moreover, TC (=1126.4 ± 4.4 K) was found to be nearly independent of tmill while for the melt-spun amorphous ribbon it was found to be substantially smaller (TC = 482 K). This is a clear indication that TC is quite sensitive to the degree of amorphosity present in the sample. The activation energy associated to the crystallization process was estimated from DSC data by using the Kissinger's method to be 193 kJ/mol.
Authors:Paula Nunes, Marília Bezerra, L. Costa, Juliana Cardoso, R. Albuquerque, M. Rodrigues, Gabriela Barin, Francilene da Silva, and A. Araújo
The purpose of this study was to evaluate the physical–chemical properties of collagen (CL) and usnic acid/collagen-based
(UAC) films, using differential thermal analysis (DTA), thermogravimetry (TG/DTG), infrared spectroscopy (FTIR), and scanning
electron microscopy (SEM). Both films were prepared by casting process using polyethylene glycol 1500 (PEG 1500) as plasticizer.
In the spectrum of UAC, similar bands of the usnic acid are observed, indicating that the polymerization (film formation)
did not affect the stability of the drug. Distinctly, DTA curve of UAC did not show an endothermic peak at 201 °C, indicative
that the drug was incorporated into the polymeric system. These results were corroborated by the scanning electron microscopy
(SEM). The TG/DTG curves of UAC presented a different thermal decomposition profile compared to the individual compounds and
CL. These findings suggest the occurrence of molecular dispersion or solubilization of the drug in the collagen film.
Authors:M. Vasconcellos, P. Bode, G. Paletti, M. Catharino, A. Ammerlaan, M. Saiki, D. Fávaro, A. Byrne, R. Baruzzi, and D. Rodrigues
Biomonitoring of mercury contamination of Brazilian Indian population groups living in the Xingu Park, a reservation situated in the Amazonic region, has revealed very high levels of mercury in hair samples as compared to controls. Total mercury was determined by INAA in most of the tribes living in the Park and methylmercury was determined by CVAAS in samples with total mercury above 10 mg/kg. Due to the fact that selenium seems to protect animals against the toxic effects of methylmercury, it was considered also of interest to determine its concentrations in the hair samples with very high mercury levels. Selenium was determined by INAA via the short-lived radionuclide 77mSe (T1/2 = 17.45 s). The correlations between selenium and mercury concentrations in Brazilian controls and in the Indian population groups are discussed.