Thermal and mechanical properties of chitosan nanocomposites with cellulose modified in ionic liquids

In this paper, ionic liquid treatment was applied to produce nanometric cellulose particles of two polymorphic forms. A complex characterization of nanofillers including wide-angle X-ray scattering, Fourier transform infrared spectroscopy, and particle size determination was performed. The evaluated ionic liquid treatment was effective in terms of nanocrystalline cellulose production, leaving chemical and supermolecular structure of the materials intact. However, nanocrystalline cellulose II was found to be more prone to ionic liquid hydrolysis leading to formation larger amount of small particles. Each nanocrystalline cellulose was subsequently mixed with a solution of chitosan, so that composite films containing 1, 3, and 5% mass/mass of nanometric filler were obtained. Reference samples of chitosan and chitosan with micrometric celluloses were also solvent casted. Thermal, mechanical, and morphological properties of films were tested and correlated with properties of filler used. The results of both, tensile tests and thermogravimetric analysis showed a significant discrepancy between composites filled with nanocrystalline cellulose I and nanocrystalline cellulose II

Moving from reclusion to partial freedom: the experience of family caregivers for disabled elderly persons assisted in a day care center

This study aimed at understanding the interactional experience between family caregivers and disabled elderly persons supported in a Day Care Center according to the caregiver's perspective. It also aimed at developing a representative theoretical model for the events experienced by such caregiver. The Grounded Theory was used as methodological framework whereas Interactional Symbolism served as the theoretical framework. Observation and interviews were used for data collection. The following phenomenon arose from the results: feeling of support by the Day Care Center, by the strength of the bond with the elderly and by spirituality in order to continue playing the challenging role of a family caregiver for a disabled elderly person. The study made possible to understand that, among these three supporting cornerstones for coping with the burden generated by the family caregiver role, the care model promoted by the Day Care Center was the intervenient variable in the process of improving the quality of life of the family caregiver-disabled elderly person binomial. This allowed the identification of the main category - moving from reclusion to partial freedom: the experience of family caregivers for disabled elderly persons assisted in a Day Care Center.O estudo teve como objetivos: compreender a experiência interacional cuidador familiar-idoso dependente apoiada por um Centro-Dia (CD), segundo a perspectiva do cuidador familiar, e desenvolver um modelo teórico representativo da experiência vivida por ele. Utilizou-se como referencial metodológico a Grounded Theory e como referencial teórico o Interacionismo Simbólico. As estratégias para a obtenção dos dados foram a observação e a entrevista. Dos resultados emergiu o fenômeno: sentindo-se apoiado pelo CD, pela força do vínculo com o idoso e pela espiritualidade para continuar desempenhando o papel desafiante de cuidador familiar de idoso dependente. O trabalho permitiu-nos compreender que dentre esses três pilares de apoio para enfrentamento da sobrecarga gerada pelo papel de familiar cuidador dependente, o modelo assistencial promovida pelo CD é o que se configurou como variável interveniente no processo de melhora da qualidade de vida do binômio cuidador familiar-idoso dependente. Isto nos possibilitou identificar a categoria central - movendo-se da reclusão à liberdade parcial: a experiência do cuidador familiar de idoso dependente assistido num CD

An inter-comparison of tidal solutions computed with a range of unstructured grid models of the Irish and Celtic Sea regions

Three finite element codes, namely TELEMAC, ADCIRC and QUODDY, are used to compute the spatial distributions of the M-2, M-4 and M-6 components of the tide in the sea region off the west coast of Britain. This region is chosen because there is an accurate topographic dataset in the area and detailed open boundary M-2 tidal forcing for driving the model. In addition, accurate solutions (based upon comparisons with extensive observations) using uniform grid finite difference models forced with these open boundary data exist for comparison purposes. By using boundary forcing, bottom topography and bottom drag coefficients identical to those used in an earlier finite difference model, there is no danger of comparing finite element solutions for "untuned unoptimised solutions" with those from a "tuned optimised solution". In addition, by placing the open boundary in all finite element calculations at the same location as that used in a previous finite difference model and using the same M-2 tidal boundary forcing and water depths, a like with like comparison of solutions derived with the various finite element models was possible. In addition, this open boundary was well removed from the shallow water region, namely the eastern Irish Sea where the higher harmonics were generated. Since these are not included in the open boundary, forcing their generation was determined by physical processes within the models. Consequently, an inter-comparison of these higher harmonics generated by the various finite element codes gives some indication of the degree of variability in the solution particularly in coastal regions from one finite element model to another. Initial calculations using high-resolution near-shore topography in the eastern Irish Sea and including "wetting and drying" showed that M-2 tidal amplitudes and phases in the region computed with TELEMAC were in good agreement with observations. The ADCIRC code gave amplitudes about 30 cm lower and phases about 8A degrees higher. For the M-4 tide, in the eastern Irish Sea amplitudes computed with TELEMAC were about 4 cm higher than ADCIRC on average, with phase differences of order 5A degrees. For the M-6 component, amplitudes and phases showed significant small-scale variability in the eastern Irish Sea, and no clear bias between the models could be found. Although setting a minimum water depth of 5 m in the near-shore region, hence removing wetting and drying, reduced the small-scale variability in the models, the differences in M-2 and M-4 tide between models remained. For M-6, a significant reduction in variability occurred in the eastern Irish Sea when a minimum 5-m water depth was specified. In this case, TELEMAC gave amplitudes that were 1 cm higher and phases 30A degrees lower than ADCIRC on average. For QUODDY in the eastern Irish Sea, average M-2 tidal amplitudes were about 10 cm higher and phase 8A degrees higher than those computed with TELEMAC. For M-4, amplitudes were approximately 2 cm higher with phases of order 15A degrees higher in the northern part of the region and 15A degrees lower in the southern part. For M-6 in the north of the region, amplitudes were 2 cm higher and about 2 cm lower in the south. Very rapid M-6 tidal-phase changes occurred in the near-shore regions. The lessons learned from this model inter-comparison study are summarised in the final section of the paper. In addition, the problems of performing a detailed model-model iner-comparison are discussed, as are the enormous difficulties of conducting a true model skill assessment that would require detailed measurements of tidal boundary forcing, near-shore topography and precise knowledge of bed types and bed forms. Such data are at present not available

Influence of non-linear effects upon surge elevations along the west coast of Britain

Abstract: A two-dimensional vertically integrated hydrodynamic finite-element model of the west coast of Britain is used to examine the response of the region to extreme meteorological forcing. The extent to which tide-surge interaction modifies the computed surge elevation and current distributions is examined in detail. The nature of the finite-element model with its ability to refine the mesh in nearshore regions is ideal for examining the influence of non-linear effects upon surges in these regions. Calculations using spatially uniform orthogonal wind stresses show that the surge elevation and current in shallow water are particularly sensitive to the method used to remove the tide as a result of the highly non-linear nature of the tide-surge interaction in these regions. The most accurate means of de-tiding the solution is by subtracting a tide derived by harmonic analysis of the tide and surge time series at the time of the surge. Subtracting a tide-only solution (the usual approach) leads to tidal energy leaking into the surge solution. Calculations show that this arises because the surge modifies the tidal amplitude and phase in shallow-water regions to such an extent that they are appreciably different to those found in the tide-only calculation. Results suggest that this problem becomes more important, as nearshore meshes are refined in an attempt to improve surge prediction. This suggests that in the future, highly accurate fine-mesh models will be required to compute total water levels without the present linear separation into tidal and surge signal used in operational surge prediction

Sustainable nanocomposite films based on bacterial cellulose and pullulan

Bionanocomposites with improved properties based on two microbial polysaccharides, pullulan and bacterial cellulose, were prepared and characterized. The novel materials were obtained through a simple green approach by casting water-based suspensions of pullulan and bacterial cellulose and characterized by TGA, RDX, tensile assays, SEM and AFM. The effect of the addition of glycerol, as a plasticizer, on the properties of the materials was also evaluated. All bionanocomposites showed considerable improvement in thermal stability and mechanical properties, compared to the unfilled pullulan films, evidenced by the significant increase in the degradation temperature (up to 40 A degrees C) and on both Young's modulus and tensile strength (increments of up to 100 and 50%, for films without glycerol and up to 8,000 and 7,000% for those plasticized with glycerol). Moreover, these bionanocomposite films are highly translucent and could be labelled as sustainable materials since they were prepared entirely from renewable resources and could find applications in areas as organic electronics, dry food packaging and in the biomedical field