Staphylococcus epidermidis adhesion on modified urea/urethane elastomers

Block urea/urethane co-polymer films present elastomeric properties with the possible tuning of their surface properties within a wide range and are therefore considered relevant surfaces for possible medical applications. In particular, thin free standing films of urea/urethane elastomers with two soft segments, polypropylene oxide and more hydrophobic polybutadiene, develop multistable states with surface topography features with remarkable regularity. Moreover, complex surface structures may be obtained by UV radiation treatment followed by suitable mechanical action and also by extraction of the elastomer with a suitable solvent. In the present work, different modified elastomer samples were assayed for Staphylococcus epidermidis adhesion during 2 h and the extent of bacterial adhesion was evaluated by automatic cell enumeration. Bacterial adhesion assays demonstrate that the typical trend relating the increase in the number of adhered bacteria with the increase of the surface roughness does not hold for all materials. Results may be interpreted taking into account both the surface topography and the different types ofmicro-phase segregation of hydrophobic and hydrophilic parts of the elastomer.Fundação para a Ciência e a Tecnologia (FCT)

Probiotics and their potential applications in active edible films and coatings.

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Evaluation of air lime and clayish earth mortars for earthen wall renders

CIAV2013 – International Conference on Vernacular Architecture, 7º ATP, VerSus, 16-20 october 2013An experimental rammed earth wall was traditionally made with local earth and characterized in terms of superficial hardness, compactness, thermal conductivity and water absorption, in exterior environmental conditions. Two mortars were made with an air lime and a mixture of three washed graduated siliceous sands, with volumetric proportions of 1:2 and 1:3 (air lime:sand). A clayish earth was characterized and applied as partial substitutions of air lime on 1:2 mortars and as partial substitutions of the finest sand on 1:3 mortars. Mortars were formulated and characterized in terms of constitution and consistency and samples of mortars applied on ceramic brick were prepared. For each volumetric proportion, mortars without earth and the ones with earth that presented the best workability were applied as renders on panels on the experimental rammed earth wall; also prismatic samples were made. The mortar samples and the renders on the wall were characterized at 90 days of age. This paper presents and discusses some of the results obtained with the characterization of the rammed earth wall, the fresh mortars and its application on the bricks and on the wall. Differences between the mortars are highlighted while their compatibility with traditional rammed earth wall is verified