J.M. Oliveira

The 12C+24Mg elastic scattering: An example of anomalous transparency at coulomb barrier energies

Abstract Fifteen complete angular distributions of the elastic scattering of 12 C+ 24 Mg were measured at energies around the Coulomb barrier ( E cm = 10.67–16 MeV). The angular distributions are strongly oscillating and could be well described by an optical potential family, whose real part was determined without continuous ambiguity. The imaginary part of this optical potential is very shallow. At four energies the inelastic scattering angular distributions leading to the 2 + state of the 24 Mg were also measured and analysed with coupled-channels calculations. The volume integrals of the optical potentials used in the coupled-channels calculations present the threshold anomaly in their energy dependence, with a clear Q -value dependence.

Development and Characterization of a Hydrogel Containing Silver Sulfadiazine for Antimicrobial Topical Applications

Development and optimization of a hydrogel with impregnated silver sulfadiazine was pursued, for antimicrobial topical applications. The selected hydrogel exhibited a homogeneous appearance, with whitish colloration and devoid of any fractures or cracks. The content in impregnated silver sulfadiazine was within established limits (1%, w/w) with a standard deviation of up to 1.28%. The hydrogel presented a good characteristic in relation to release of the active antimicrobial principle, verified through swelling tests and antimicrobial activity. The swelling tests indicated a higher increase in weight during the first 6 h of contact with a moist environment, with a maximum value of 266.00 ± 0.81, and with maintenance of the original shape of the hydrogel. The impregnated silver sulfadiazine presented antimicrobial activity, as expected, indicating a prolonged release of the drug. The infrared spectra of the hydrogel with impregnated silver sulfadiazine indicated that the drug did not engage in any bonds with the polymeric matrix, which otherwise could have reduced its antimicrobial activity. The mechanical resistance tests produced good results, indicating that the hydrogels may be utilized in different locations of the human body with skin lesions.

Porosity measurement of solid pharmaceutical dosage forms by gamma-ray transmission

The aim of the present work is the determination of porosity in tablets by using the gamma-ray transmission technique. Tablet dissolution depends on some inherent characteristics of the manufacturing process, such as compression force, tablet volume, density and porosity, nature of excipients, preparation methods and its physical-chemical properties. Porosity is a measure of empty spaces in a material and can be determined by various techniques. In this paper, we propose the use of a gamma-ray transmission technique to obtain the porosity of experimental formulation of tablets. The results of porosity were compared with those obtained by using conventional methodology (density and mercury intrusion). The experimental setup for gamma-ray transmission consists of a gamma-ray source of (241)Am (photons of 59.6 keV and an activity of 3.7 × 10(9)Bq), an NaI(Tl) scintillation detector, collimators and a standard gamma-ray spectrometry electronics. Our results suggest that the gamma-ray transmission technique is a powerful tool for non-destructive porosity quantification of solid pharmaceutical forms and presents smaller errors than those obtained with conventional methodologies.

Back-angle anomaly and coupling between seven reaction channels of 12C + 24Mg using algebraic scattering theory

Abstract We measured six fairly complete angular distributions of elastic, inelastic and α-transfer reactions of the 12 C + 24 Mg system at E CM =25.2 MeV. We performed coupled channels calculations using algebraic scattering theory with the nuclear algebraic potential derived from nuclear phase shifts and using the available structure information for the inelastic coupling strengths. The back angle rise in the elastic cross section is fully explained by the couplings between elastic and transfer channels.

Anomalous heavy ion scattering near the Coulomb barrier

Abstract Striking oscillations were found in the elastic scattering of 12 C + 24 Mg near the Coulomb barrier. These oscillations are not reproduced by the standard potentials at higher energies and provide the determination of the optical potential without continuous ambiguity. The dispersion relation between the real and imaginary parts of this optical potential is not satisfied at the strong absorption radius, but holds for their volume integrals.

Scaffolds and tissue regeneration: An overview of the functional properties of selected organic tissues.

Tissue engineering plays a significant role both in the re-establishment of functions and regeneration of organic tissues. Success in manufacturing projects for biological scaffolds, for the purpose of tissue regeneration, is conditioned by the selection of parameters such as the biomaterial, the device architecture, and the specificities of the cells making up the organic tissue to create, in vivo, a microenvironment that preserves and further enhances the proliferation of a specific cell phenotype. To support this approach, we have screened scientific publications that show biomedical applications of scaffolds, biomechanical, morphological, biochemical, and hemodynamic characteristics of the target organic tissues, and the possible interactions between different cell matrices and biological scaffolds. This review article provides an overview on the biomedical application of scaffolds and on the characteristics of the (bio)materials commonly used for manufacturing these biological devices used in tissue engineering, taking into consideration the cellular specificity of the target tissue.

Development and Characterization of a Hydrogel Containing Nitrofurazone for Antimicrobial Topical Applications

The goal of the research work entertained herein was the development and characterization of a poly-(vinyl alcohol) (PVA) hydrogel cross-linked with glutaraldehyde and impregnated with 0.2% (w/w) nitrofurazone (NTZ), for topical applications. To verify the active principle release capability, one has determined (i) swelling profile, (ii) in vitro release of NTZ via UV-VIS spectrophotometry, and (iii) antimicrobial activity via exposure to the hydrogel of ATCC strains of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The optimized hydrogel was further characterized via scanning electron microscopy (SEM), infrared spectroscopy with Fourier transform, moisture content determinations and thermal analyses via thermal gravimetry (TGA). Swelling tests revealed a mass increase from 100±5% up to 350±11%. Incorporated NTZ displayed bactericidal activity, as expected, being released in a linearly controlled fashion above 6 µg/mL during experiment timeframes of 14 h. SEM analyses allowed verification of a homogeneous surface morphology, while infrared spectra showed that NTZ did not bind strongly to the cross-linked polymer. Furthermore, results from thermal analyses suggested a loss of thermal stability arising from incorporation of NTZ in the hydrogel. The optimized hydrogel exhibited characteristics with high potential for (antimicrobial) treatment of skin lesions.

Total reaction cross section and forward glory for 12C + 16O

Abstract A method based on the generalized optical theorem is proposed for the determination of the total reaction cross section from elastic angular distributions. This method was applied to 16 complete elastic angular distributions of the 12 C + 16 O at energies between E c.m =8.55 MeV and E c.m = 26.74 MeV. Some of the angular distributions were measured at the Sao Paulo Pelletron Laboratory. Angular distributions measured by the Erlangen and Saclay groups were also used. The reaction cross section is compared with fusion measurements and with σ R obtained by indirect methods. The existence and conditions for the observation of the nuclear forward glory scattering are investigated.

Orbiting in the algebraic scattering framework

Abstract Experimental results on orbiting phenomena in 18 O+ 10,11 B systems at E c.m. =18.8 and 19.9 MeV are presented. We show that all features of the orbiting phenomena of 11 B( 18 O, 18 O) 11 B and related transfer reactions are explained by a complete coupled-channels calculation in the AST framework. It is also shown that the orbiting features and the back-angle anomaly are strongly related and explained by the same channel coupling.

Bone mineral density is reduced by telmisartan in male spontaneously hypertensive rats

BACKGROUND Telmisartan, an angiotensin AT1 receptor blocker, and treadmill running were compared for their effects on bone mineral density (BMD) and biomechanical properties of male spontaneously hypertensive rats (SHR). It was hypothesized that running (18m/min/60min/d) and telmisartan (5mg/kg/d) would have a positive effect on bone parameters. METHODS Three-month-old male SHRs were divided into three groups: sedentary (S), telmisartan (T), and exercise (E). At the end of an 8-week protocol, femur and lumbar vertebrae were analyzed by dual-energy X-ray absorptiometry (DXA) for bone mineral density and by the three-point bending test for biomechanical properties. Blood pressure in all groups was measured by a tail-cuff manometer. RESULTS Telmisartan and treadmill running reduced blood pressure when compared to the sedentary group; however, telmisartan did not improve bone characteristics. Instead, it reduced BMD of femur total and lumbar vertebrae and worsened bone biomechanic properties. Treadmill running maintained bone characteristics and hence was effective in maintaining bone health. CONCLUSION Results showed that telmisartan negatively affected bones suggesting that caution should be taken in possible therapeutic applications for protecting bone health in hypertensive conditions. More studies are necessary to clarify the mechanisms through which telmisartan favors bone loss in this model.