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The present paper analyzes the different biomass burner technologies used in Uruguay from the combustion process standpoint, seen as a system of processes with highly non linear mechanisms of mass, momentum and energy transfer phenomena. Technologies based on fixed, moving and fluidized bed are compared and contrasted, with a special emphasis on the effect that fuel quality has on the choice of technology, given the variations found in the biomass quality, in terms of its size distribution and composition. The problem of designing equipment for any given chemical process is stated and the inherent difficulty when scaling an existing installation is proven. The need to acquire knowledge of the processes and the relationships between them is essential for a successful scale-up. In the majority of cases, the geometry has to be altered, dramatically affecting the mechanisms within. The highly coupled non linear system renders analytical solutions impossible, so approximate numerical solutions are sought. Numerical results of a study of the sensitivity of bed permeability on combustion stability are shown. [ABSTRACT FROM AUTHOR]

The Institute of Testing of Materials of the Engineering School of Montevideo developed a standard method in reference to the quality of biological tissues of human origin currently employed in clinical human transplantation in our country. In a joint study with researchers from the Medicine (BNOT) and the Chemistry Schools, the authors tested cardiovascular tissues preserved by programmed liquid nitrogen freezing, evaluating quality criteria. Comparative tests of molecular crystalographic and biomechanical variables in the fresh and defrosted condition were carried out in laboratory setting. Preliminary results are shown. The biomechanical assays were carried out on six fresh and seven defrozen anular segments, obtained from donors of BNOT. In relation to the donors selection, ablative and vessels dissection techniques, procedures regulated by BNOT were applied. With the same criteria tissues in the antibiotic sterile areas were processed , the use of cryopreservation methods, bottling, programmed freezing curve and storage in liquid nitrogen vapors to -142 ºC . Transversal uniaxial traction tests were made, as X rays diffraction tests from its internal aspects were also made, analysing crystalline structures on fresh and frozen samples. It is concluded for that sample, that although there is an increased stiffness in the defrosted stuff, it is not statistically significant. Instead, the x ray diffraction profiles, show modifications in the molecular arrangement between fresh and defrosted samples which allow to assess the thermal effect and so evaluate the quality of the procedure. The complex biomechanical behaviour of the vascular polymers and the effect provoked on them by the cryogenic conditions, need further multi-disciplinary studies in its functional and structural aspects, that this group of researchers continues to carry out. [ABSTRACT FROM AUTHOR]