[en] Document available in extended abstract form only. In the KBS-3 concept for the nuclear waste repository, designed by the Swedish Nuclear Fuel and Waste Management Co. (SKB), the bentonite buffer is placed around the copper canisters that contain the spent nuclear fuel, isolating it of the host rock. In order to check - hypotheses for the evolution of the bentonite buffer under the thermo-hydraulic conditions expected in a KBS-3 repository, SKB is conducting a series of long term buffer material (LOT) tests at the Aespoe Hard Rock Laboratory (HRL). In the present work, numerical simulations are developed to simulate: i) thermo-hydraulic processes; ii) geochemical reactions and; iii) transport of solutes, that have been measured in the LOT A2 test, and, that are expected in the near-field of a KBS-3 repository. The numerical model for the LOT A2 test is based on analytical results and on field-scale experiments. The validation of this model allows us to implement it for the thermal period of the near field of the KBS-3 repository, based on previous modelling exercises. During the operation of a KBS-3 repository (after deposition of the copper canisters), the unsaturated bentonite will be submitted to a relatively high thermal gradient, induced by the radioactive decay of the spent nuclear fuel. On the other hand, the saturated host rock will provide aqueous solution to the unsaturated bentonite, induced by differential hydraulic pressures, under specific thermal and mechanic conditions. In this context, the bentonite will gradually become fully water saturated. Experimental results indicate that during the saturation period, the transport of solutes in the bentonite buffer will be influenced by water uptake from the surrounding host rock towards the wetting front, and also by a cyclic evaporation/condensation process, induced by the thermal gradient. Our numerical models take into account the transport of solutes and geochemical reactions under nonisothermal conditions, and in a scenario of variable pore water saturation. The reference groundwater composition that represents the host rock groundwater (mainly located in fractures) is taken from a borehole drilled in the Aespoe HRL that supplied the LOT A2 test. The initial pore water composition of the bentonite buffer is based on the experimental results attained in Karnland et al. (2008). From the mineralogical description of the MX-80 bentonite, and under the pH and redox conditions expected for the near-field of the future KBS-3 repository, the main reactive minerals of the bentonite buffer are montmorillonite, gypsum and pyrite. In terms of its solubility, montmorillonite seems to remain relatively stable under the geochemical and thermo-hydraulic conditions of a KBS-3 repository, and therefore, it only participates in cation exchange reactions. Finally, from the results attained in previous works, anhydrite and calcite are let to precipitate if over-saturation is reached. The numerical model developed for the LOT A2 test indicates that the bentonite buffer is fully water saturated within the first half-year which is in agreement with measured data. Numerical results indicate that, despite the evaporation/condensation cycling, the chloride transported by the flow of Aespoe groundwater into the bentonite buffer behaves conservatively (no chloride salts precipitate). In addition, numerical results indicate that the behaviour of anhydrite, gypsum and calcite is influenced by the thermal gradient that is established during the saturation period of the bentonite buffer. (authors)

[en] Bacaba is widely consumed by the Amazonian population, and is promising for the production of cooking oil. The objective of this research was to determine the parameters of bacaba oil extraction with supercritical CO2: the fatty acid composition, functional quality, oxidative stability, spectroscopic profile and antioxidant activity of the extracted oil. Extractions of bacaba (Oenocarpus bacaba) oil were performed with supercritical CO2 at temperatures of 40 and 60 ºC, with pressures varying from 120 to 420 bar. The highest mass yield was 60.39 ± 0.72% on a dry basis, obtained in the isotherm of 60 °C and 420 bar. Oleic acid was the major compound. The Infrared spectroscopic profile showed the predominance of unsaturated fatty acids. The results indicate that bacaba oil presents good functional quality.

[en] The thermoluminescent response of beryl in its aquamarine variety (Be₃Al₂(SiO₃)₆:Fe) is reported. The samples were irradiated at room temperature using a β radiation source (⁹⁰Sr/⁹⁰Y) at a dose rate of 0.10 Gys^-1. Measurements performed at 1° C s^-1 after irradiation from 4 to 80 Gy show a prominent brightness peak around 75° C and three secondary peaks at 113, 188, and 306° C, respectively. The position of the main peak is dose independent between 4 and 80 Gy, suggesting first-order kinetics. For a single dose of 1 Gy at different heating rates, the main peak (~ 75° C) shows a shift toward high temperatures and a decrease in maximum height and area. The kinetic analysis of the main peak was carried out using the initial rise, full brightness peak, and dimensionless fitting method; while the full curve analysis was performed using the curve fitting technique. The results show that the main brightness peak follows first-order kinetics, its activation energy is of the order of 1 eV and it has a frequency factor of the order of 10¹² s^-1 as had been reported. The results are independent of the dose and heating rate used. (author)

[en] Measurements of the electric quadrupole interactions were used to characterize pure and Fe-doped In₂O₃ samples using perturbed γ-γ angular correlation (PAC) technique with ¹¹¹In-¹¹¹Cd radioactive probe. The samples of pure as well as 1 % and 5 % Fe-doped In₂O₃ were prepared by sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS). The PAC measurements were carried out with a conventional fast-slow coincidence set-up using four BaF₂ detectors as a function of temperature from 295 K to 1073 K. The powder XRD spectra analyzed with Rietveld method as well as SEM and EDS results showed that Fe-doped samples are homogeneous without any secondary iron oxide phases. The PAC spectra of pure and 1 % Fe-doped In₂O₃ show well-known characteristic quadrupole frequencies for the two non-equivalent sites in the bixbyte structure. The hyperfine parameters in these cases change little with temperature. For the 5 % Fe-doped sample however the PAC spectra changed significantly and a third frequency with large η appears.

[en] Road pavements need a deep characterization of the surface layer, with which the vehicles have direct contact and, therefore, must provide security to the users. The use of permeable asphalt pavements (PAP) with porous layers has provide obvious advantages in reducing runoff and the rainwater infiltration into the soil or for storage. However, the study of the interaction between the pavement surface layer and the tire rubber requires additional tests in terms of texture and friction, since they are important parameters for the design, construction, management, maintenance and roads safety. Considering the application of a PAP in a parking lot, the study objective was to characterize in the field the pavement surface in terms of mean texture depth (MTD) and skid resistance (Pendulum test value, PTV). The methods used were the volumetric technique by the patch test and the pendulum test, according to EN 13036-1 and EN 13036-4, respectively. The double layer porous asphalt (DLPA) at the surface is characterized by having a structure with high voids content that led to results of clearly rougher macrotexture and good skid resistance. The normalized limit values were met, however, a very strong correlation between MTD and PTV was not observed. A comparison was also made with porous surfaces of other studies and it was found that porous asphalt has a good behaviour at the start of construction which may tend to improve in the long term. From the study, it is concluded that the PAP presents good performance of the surface layer, providing road safety to users. (paper)

No abstract available

No abstract available

[en] In the present work, Bi₂Sr₂CaCu₂O_x (Bi-2212) commercial and homemade precursor powders were investigated. Precursors with different nominal compositions were pressed and melt-processed into silver molds, being then heated at 890-920 deg. C, under 1 atm O2. The bulk samples were then slowly cooled and further annealed at 850 deg. C with a subsequent annealing step at 700 deg. C. The properties of the fully processed samples depended strongly on the maximum processing temperature as well as on the precursor powder employed. Fully processed samples exhibited Ic = 84-146 A and Jc = 800-1400 A/cm², at 77 K. The Bi-2212 stoichiometric nominal composition provided the best results. The correlation between the final microstructure and the properties is not clear

[en] Magnetic nanoparticles from magnetic colloidal suspensions were incorporated in the urethane/urea elastomer (PU/PBDO) by adding to the prepolymers solution in toluene diverse amounts of magnetite grains. It is shown that ferrofluid grains can be efficiently incorporated into the elastomer according to this procedure. Mechanical and optical experiments performed show that the elastomer preparation procedure (casting) introduces a structural anisotropy on the optically isotropic sample. This fact is put in evidence by the measurements of the Young's moduli and orientation of the sample's optical axis under stress. The dependence of the phase shift of both the pure and ferrofluid-doped elastomer samples under strain is linear, and the strain-optic coefficient is show to be linear with the ferrofluid concentration