Authors:Maria Ribeiro da Silva, N. Araújo, A. Silva, L. da Silva, N. Barros, J. Gonçalves, and M. Ribeiro da Silva
The standard (p0=0.1
MPa) molar enthalpies of formation, at T=298.15
K, in the gaseous phase, for three tetradentate Schiff bases involving a N2O2
(H2salch), N,N’-bis(acetylacetone)cyclohexanediimine (H2acacch)
(H2bzacch), were determined from their enthalpies of
combustion and sublimation, obtained by static bomb calorimetry in oxygen
and by the Knudsen effusion technique, respectively. The results are compared
with identical parameters for related compounds previously studied, resulting
from the condensation of salicylaldehyde or β-diketone with aliphatic
A simple and efficient method to isolate228Ra from natural thorium oxalate was developed. It consists in the coprecipitation of radium by hydrolysis of saturated solutions
of ammonium thoroxalate followed by ion-exchange chromatography on Amberlite IR-120. The final product is carrier-free and
pure enough for the preparation of thin sources for alpha and conversion electrons spectrometry. The radium coprecipitation
utilized in the first step of this method, could be used to separate thorium from most of its radioactive daughters, decreasing
the hazards of manipulation of large quantities of thorium.
Ionizing radiation was used for the purpose of reducing bacterial contamination in mechanically deboned chicken meat (MDCM).
Irradiated and non-irradiated MDCM stored at -18±1 °C, and samples were taken at zero time and at 30-day intervals up to 90
days for 2-thiobarbituric acid reactive substances, sensory and microbiological analyses. The results obtained for the microbiological,
sensory and lipid oxidation evaluations, showed that the MDCM samples irradiated with doses of 3.0 and 4.0 kGy were all considered
acceptable during 90 days of frozen storage.
Authors:J. de Britto, M. Bastos, R. da Silva, and A. da Silva
A method for the production of no carrier added and residue free22Na, was developed via the24Mg/d, /22Na nuclear reaction applying 14 MeV deuterons and a high current Mg–Cu target. The yield for the reaction target. The yield for the reaction was measured and the chemical separation performed using a Dowex 50WX8 resin in H+ form. The overall yield was higher than 98%. Residue could not be detected. All experiments were carried out at IEN's CV-28 cyclotron.
Authors:J. Rodrigues Silva, A. de Melo Ferreira, and A. da Costa
The biosorption of uranium by the seaweed Sargassum filipendula was investigated under dynamic conditions at various bed heights. Our results indicate that a bed height of 40.0 cm (111.9
g biomass) was the most efficient for long-term operation of the continuous system. Our results also indicate that the effluent
solutions produced are in accordance with Brazilian legislation for safe discharge of uranium in aqueous streams. The efficiency
of the process increased with an increase in bed height from 5.0 to 40.0 cm due to changes in the transfer zone. In treatment
of a real effluent contaminated with uranium, stable heavy metals and essential metals, 64% of the uranium was biosorbed,
as well as the stable heavy metals chromium, lead and barium. The essential metals calcium, magnesium, iron and manganese
were not biosorbed by the seaweed, in fact, their concentrations in the solution increased due to ion-exchange mechanisms
with the constituent polysaccharides of the biomass. Another important result was the 85–87% reduction of mass obtained after
drying and calcination of the biomass. This is a relevant indication that long-term storage of biomass loaded with radionuclides
and heavy metals is possible after concentration of the contaminants. In the present work, the reduction in total mass of
the loaded biomass was considerable, thus facilitating storage of the contaminated seaweed.
Authors:J. de Britto, A. de Sousa, and A. da Silva
A gas target chamber was built for the measurement of the thick target yield of22Na from the bombardment of natural Ne with a cyclotron beam of 27 MeV -particles. An evaluation of these means of production as compared with other methods, especially with time consuming chemical separation methods described in the literature is presented.
with 24-MeV protons from IEN'S CV-28 cyclotron. The separation is based on the properties of a chelating carboxylic acid cation exchange resin column which at pH 4.5 retains lead while thallim is easily eluted. This column can also be used as a regular generator to produced greater quantities of201Tl but at the expense of more elutions.
Authors:J. Martín, A. Martínez-Aguirre, M. Respaldiza, and M. da Silva
The studied marsh area is located at the southwest of Spain in an estuarine system formed by the confluence of the Odiel river and the Atlantic ocean. 23 samples collected in the marsh have been analysed by Thick Target Proton Induced X-ray Emission using 2 MeV protons from the 3 MV Van de Graaff accelerator of the ITN. Elemental concentrations in the samples are affected by the Atlantic ocean, the materials transported by the Odiel river and the wastes discharged by the factories of a nearby industrial area. The study has shown that certain areas of the estuary present high concentrations of P, Cu, Zn, As and Pb, which were attributed to the operation of a phosphate fertilizer factory and a Cu extraction factory. The mining activity carried out near the source of the river could be also responsible of part of this contamination. Finally, the spatial distribution of the contamination has reflected the dinamic of the Odiel river waters, due to tidal movements, into the marsh area.