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Objectives: The aim of this study is to evaluate the effect of the different conditions of curing on the residual monomer levels, hardness and impact strength of a microwave-polymerised acrylic resin., Methods: The material was polymerised in a microwave oven in four different conditions of power and curing time. The kinetics of release of residual monomer in water was evaluated by spectrophotometric method up to 24 h. The hardness of the sample was determined by the Rockwell method and the impact strength tested by the Charpy method. The results were subjected to statistical analysis using ANOVA and Tukey's test for comparison., Results: The levels of residual monomer were found dependent upon the curing conditions and they were correlated with the values of impact strength. Significant differences were observed in this property regarding the analysed conditions (p<0.001)., Conclusions: From the appropriate selection of power and time of curing of the resin, it is possible to optimise the level of residual monomer and a low cytotoxicity keeping at the same time the best mechanical properties.

In this communication, we revise some aspects of the [ideal gas/Van der Waals fluid] partition, derived in an earlier publication. The general character of the conclusions concerning the dependence of the partial molar free energy of solution, deltaGs(n), on the chain length, n, of linear solute molecules is shown through the relationship with more general partition formulations. Simultaneously, the correction of an error in the expression of the retention time dependence on the phase ratio of the chromatographic column, beta, is carried out. The misleading source of this error was redundant accounting in the solute translational contribution to deltaGs(n).

This paper presents a model for pH-dependent adsorption of an ionic homopolypeptide with secondary structure on a flat surface. This model is developed by generalization of a discrete model of semistiff chain with short-range interaction, between homopolypeptide chain and surface. The presence of intramolecular repulsive interaction as well as secondary structure is introduced here by modified Zimm-Bragg stabilization parameters. The model predicts that in the case of low degree of ionization, the adsorption behaviour of an ionic and non-ionic homopolypeptide are qualitatively similar (i.e. both show a second-order phase-transition, characteristic of this phenomenon). We also illustrate the prediction of the model about the critical absorption energy in the case of selective interaction, and show that a discontinuity in the melting-temperature behaviour appears when the pH is tuned to a critical pH value (pHc).