Biodegradable polyesters reinforced with triclosan loaded polylactide micro/nanofibers: Properties, release and biocompatibility

Mechanical properties and drug release behavior were studied for three biodegradable polyester matrices (polycaprolactone, poly(nonamethylene azelate) and the copolymer derived from 1,9-nonanediol and an equimolar mixture of azelaic and pimelic acids) reinforced with polylactide (PLA) fibers. Electrospinning was used to produce suitable mats constituted by fibers of different diameters (i.e. from micro- to nanoscale) and a homogeneous dispersion of a representative hydrophobic drug (i.e. triclosan). Fabrics were prepared by a molding process, which allowed cold crystallization of PLA micro/nanofibers and hot crystallization of the polyester matrices. The orientation of PLA molecules during electrospinning favored the crystallization process, which was slightly enhanced when the diameter decreased. Incorporation of PLA micro/nanofibers led to a significant increase in the elastic modulus and tensile strength, and in general to a decrease in the strain at break. The brittle fracture was clearer when high molecular weight samples with high plastic deformation were employed. Large differences in the release behavior were detected depending on the loading process, fiber diameter size and hydrophobicity of the polyester matrix. The release of samples with the drug only loaded into the reinforcing fibers was initially fast and then became slow and sustained, resulting in longer lasting antimicrobial activity. Biocompatibility of all samples studied was demonstrated by adhesion and proliferation assays using HEp-2 cell cultures

Combined microwave–convective drying of saccharomyces cerevisiae based yeast

Attention is paid to drying as a downstream processing of foodstuff as it is used finally for human consumption. In some cases the conventional (convective, contact or infrared) drying processes can damage the quality of food due to crusting phenomena, overheating or protein denaturation. Better results can be obtained using combined microwave–convective dehydration.The paper mainly focuses on the investigation of drying Saccharomyces cerevisiaepulp using the method of dielectric dehydration. A dried product with a residual fermentative activity of over 80% was produced with the application of a microwave–convective drying system. As a result the moisture content was lower than 10% calculated on dry basis. We permanently regulated the incident microwave power manually in order to eliminate the mentioned disadvantageous effects. This type of regulation was applied when the surface temperature reached 45 °C

Micro- and Nanotexturization of Liquid Silicone Rubber Surfaces by Injection Molding Using Hybrid Polymer Inlays

Micro- and nanotexturization of surfaces can give to the parts different advanced functionalities, such as superhydrophobicity, self-cleaning, or antibacterial capabilities. These advanced properties in combination with the biocompatibility of Liquid Silicone Rubber are an interesting approach for obtaining high-performance medical devices. The industrial production of surface textures in polymeric materials is through the replication technique, and the best option to attain a high production rate is injection molding. Moreover, its low viscosity during processing can provide an accurate replication capacity by the easy filling by capillarity of the microtextures. An innovative replicating technique for Liquid Silicone Rubber is presented by studying the replication of different shaped textures within a diameter range of between 2 and 50 mu m. The copying process consists in the overmolding of a textured polymeric inlay obtained by nanoimprint lithography. At the end of the process, a textured part is obtained, while the imprinted film remains in the mold. The injection molding parameters are optimized to increase the replication accuracy, and their effect on texture replicability is analyzed and discussed. Finally, it is shown that the textured surfaces improve their wettability behavior, which is a necessary and important characteristic in the development of biomedical devices

Biodegradable free-standing nanomembranes of conducting polymer:polyester blends as bioactive platforms for tissue engineering

The present study reports the fabrication of free-standing nanomembranes with semiconducting and biodegradable properties. Nanomembranes have been prepared by spin-coating mixtures of a semiconducting polythiophene derivative, poly(3-thiophene methyl acetate), and a biodegradable polyester, poly(tetramethylene succinate). Both the roughness and thickness of the nanomembranes, which ranged from 3 to 20 nm and from 20 to 80 nm, respectively, were precisely controlled through the spin-coater speed and the solvent evaporation properties. Nanomembranes made of conducting polymer/polyester blends, which are able to retain the properties of the individual polymers, are stable in air and in ethanol solution for more than one year, facilitating their manipulation. Enzymatic degradation essays indicated that the ultra-thin films are biodegradable due to the presence of the aliphatic polyester. Interestingly, adhesion and proliferation assays with epithelial cells revealed that the behavior of the blend as cellular matrix is superior to that of the two individual polymers, validating the use of the nanomembranes as bioactive substrates for tissue regeneration.222585594MICINNFEDER [MAT2009-09138, MAT2009-11513]DIUE of the Generalitat de Catalunya [2009SGR925, 2009SGR1208, XRQTC]Euro Brazilian Windows agency [41309-EM-1-2008-PT-ERAMUNDUS-ECW-L16]FPU-UPCGeneralitat de CatalunyaFEDER [MAT2009-09138, MAT2009-11513]DIUE of the Generalitat de Catalunya [2009SGR925, 2009SGR1208, XRQTC]Euro Brazilian Windows agency [41309-EM-1-2008-PT-ERAMUNDUS-ECW-L16

Potential of ultrasound technology for the preparation of microdevices

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Development of antimicrobial polymers by incorporation of bacteriophages

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Requerimientos de usuarios de la edificación traducidos en una metodología de apoyo a la decisión

Different actors of building sector have developed various methods that assess the quality of its buildings in response to environmental issues. The methods developed in a specific context, have achieved a great popularity in recent years, but also an ambiguity in its measurement, a confusion in the objective pursued, forgetting the context in which they are intended. This paper develops a methodology of decision support, which evaluates the performance of existing buildings from the point of view of energy and user satisfaction, to decide between rehabilitation or demolition. The case of study is an university campus, which brings together different uses and users, and therefore different quality and comfort requirements. The indicators in the methodology consider this complexity, delivering its results in a single evaluation profile and allowing to be applied in different contexts.<br><br>Diferentes actores del sector de la edificación han desarrollado diversos métodos que evalúan la calidad de sus edificios en respuesta a problemáticas medioambientales. Métodos desarrollados en un contexto específico, en este último tiempo han alcanzado una gran popularidad, pero al mismo tiempo ambigüedad en su medición, confusión en el objetivo que persiguen, olvidando el contexto en los que han sido concebidos. En este trabajo se desarrolla una metodología de apoyo a la decisión que evalúa el comportamiento de edificios terciarios en fase de explotación desde el punto de vista energético-medioambiental y satisfacción de sus usuarios, con el fin de decidir entre una rehabilitación o la demolición. El caso de estudio es un campus universitario en Francia, el cual reúne distintos usos y usuarios, y por lo tanto distintos requerimientos de calidad y de confort. Los indicadores que conforman la metodología consideran esta complejidad entregando sus resultados en un único perfil de evaluación, permitiendo ser aplicados en distintos contextos

Influence of microstructure on the crystallization of segmented copolymers constituted by glycolide and trimethylene carbonate units

Hot and cold non-isothermal crystallization of copolymers having glycolide hard segments and glycolide-cotrimethylene carbonate soft segments was investigated by calorimetry, optical microscopy and synchrotron radiation experiments. The effect of composition and microstructural changes on thermal properties and morphology of crystallized samples was analyzed. Significant differences were found between the nucleation density of spherulites developed during cold crystallization. Crystallizations from the melt were characterized by a lamellar insertion mechanism and a broad distribution of crystal layer widths. By contrast, cold crystallized samples gave rise to practically constant long periods and narrower distributions. Soft segments with high glycolide content were more easily incorporated in the crystalline phase by decreasing the hard segment content of the sample. A significant decrease on the melting point was observed as well as a decrease of the amorphous layer thickness and an increase of the crystalline lamellar thickness when the sample was hot and cold crystallized, respectively

Horizontal axis wind turbine systems: optimization using genetic algorithms

A method for the optimization of a grid-connected wind turbine system is presented. The behaviour of the system components is coupled in a non-linear way, and optimization must take into account technical and economical aspects of the complete system design. The annual electrical energy cost is estimated using a cost model for the wind turbine rotor, nacelle and tower and an energy output model based on the performance envelopes of the power coefficient of the rotor, C P , on the Weibull parameters k and c and on the power law coefficient ˛of the wind profile. In this study the site is defined with these three parameters and the extreme wind speed V max. The model parameters vary within a range of possible values. Other elements of the project (foundation, grid connection, financing cost, etc.) are taken into account through coefficients. The optimal values of the parameters are determined using genetic algorithms, which appear to be efficient for such a problem. These optimal values were found to be very different for a Mediterranean site and a northern European site using our numerical model. Optimal wind turbines at the Mediterranean sites considered in this article have an excellent profitability compared with reference northern European wind turbines. Most of the existing wind turbines appear to be well designed for northern European sites but not for Mediterranean sites