Porous ceramic materials based on calcium phosphate compounds (CFC) have been studied and developed for several biomedical
applications such as implants, controlled drug delivery, and radioactive sources for brachytherapy. Two kinds of hydroxyapatite
(HAp) powders and their ceramic bodies were characterized. In this study, non-radioactive iodine was incorporated in two types
of biodegradable hydroxyapatite-based porous matrices (HA and HACL). The results reveal that both systems present a high capacity
of incorporating iodine. The quantity of incorporated iodine was measured by neutron activation analysis (NAA). The porous
ceramic matrices based on hydroxyapatite demonstrated a great potential for uses in low dose rate (LDR) brachytherapy.
Authors:Marta Conceição, V. Fernandes Jr, A. Bezerra, M. Silva, Iêda Santos, F. Silva, and A. Souza
Diesel oil has an important role in the field
of urban traffic as well as in the transportation of products. However, the
amount of the non-renewable sources is continuously decreasing. This fact
and the environmental requirements brought the necessity to search for other,
renewable sources. This paper aimed the dynamic kinetic calculation of thermal
decomposition of castor oil, methanol biodiesel and ethanol biodiesel using
Coats–Redfern, Madhusudanan and Ozawa methods. On the base of the thermogravimetric
curves the following thermal stability order could be established: castor
oil>ethanol biodiesel>methanol biodiesel. Kinetic data presented coherent
results. Methanol biodiesel presented lower activation energy than ethanol
biodiesel, suggesting that methanol biodiesel has a better quality for combustion.
Authors:S. Silva, M. Conceiçăo, A. Souza, S. Prasad, M. Silva, V. Fernandes, A. Araújo, and F. Sinfrônio
The powder and the bran of algaroba pods, submitted to drying temperatures of 55, 65, 75, 85, 95 and 105C, were studied by
conventional and thermogravimetric methods. The dynamic thermogravimetric curves of the samples indicated the following thermal
stability order: 105>55>65>95>85>75C. The powder and the bran of algaroba pods, dried at 55C, presented protein content
higher and isothermal thermogravimetric profiles comparable. The calorimetric curves of samples, dried at 55C, indicated
the gelatinization of starch.
Authors:C. Blanco, E. Sosinski, B. Santos, M. Silva, and V. Pillar
The question addressed in this paper is whether plant traits and plant functional types related to forage selection by grazers are also related to those expressing short-term community response after grazing. Vegetation of natural
grassland in south Brazil was examined for species composition and locally described for seven morphological traits before and after a controlled grazing period by bovine cattle. An optimization algorithm was used for the identification of plant functional
T) and plant functional
T)-in this case, groups of plants similar in a given set of traits (assessed before and after one grazing short period, respectively) and in their association to grazing intensity. The results have shown that plant traits optimally defining plant types related to forage selection (PF
Ts) were the same traits optimally defining short-term community response to grazing (PF
Ts); also similar trends of plant morphological variation were observed among populations before and after grazing, based on the traits’ correlation structure. However, at the community level the correlation vanished, since similar communities described by the performances of PF
Ts were not as similar when described by PF
Ts. Hence, whether plant functional types related to forage selection (effect types) are also related to community response to grazing may depend on the level of organization considered. The paper advances on the operational definition of possible overlaps between effect and response plant functional types.
Authors:V. Borghi, L. Lin, S. Silva, E. Haber, and B. Wajchenberg
This work reports the radioiodination of human thyrotropin (hTSH) in our laboratory (IPEN) and evaluates its quality in comparison with a commercial product. The radioiodination yield obtained in 20 experiments ranged from 18.5 to 56.3%, while the purification recovery ranged from 75.5 to 124.0% and the specific activity ranged from 1.01 to 3.10 MBq g–1. The values for the distribution coefficient revealed in the purification of radioiodinated hTSH ranged from 0.232 to 0.371. When tested concomitantly in the same radioimmunoassay system, the IPEN and the commercial tracer presented parallel standard curves. A highly significant correlation ion was observed between the quality control samples estimated through both curves (p<0.001). These results confirm the quality of the hTSH radioiodinated at IPEN and suggest the acquirement of self-sufficiency in this in vitro nuclear technology.
Authors:A. Silva, M. Souza, J. Aquino, V. Fernandes, and A. Araújo
The coke removal of HZSM-12 zeolite deactivated in the reaction of n-heptane cracking was studied by thermogravimetry using
two multiple heating rate integral kinetics models proposed by Ozawa-Flynn-Wall and Vyazovkin to obtain the activation energy
of process of thermoxidation of coke. The results obtained by both models presented excellent accordance with the related
Authors:A. Araujo, V. Fernandes, A. Silva, and J. Diniz
The evaluation of the crystallinity of several samples of ALPO-11 was performed by X-ray diffraction and thermogravimetry.
Through XRD, the degrees of crystallinity of the samples were determined by the measurement of the area of the peaks at 2γ
ranging from 20.7 to 24.1 degrees. The sample that presented the largest area was considered as 100% crystalline and the areas
of the other samples were normalized in relation to this. From TG, the degree of crystallinity was determined considering
the mass loss in the temperature range from 453 to 653 K that is related to remotion of di-isopropylamine molecules used during
the synthesis procedure. The quantity of diisopropylamine on the material is proportional to the degree of crystallinity.