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Nanostructured polymeric coatings based on chitosan and dopamine-modified hyalu...

In a marine environment, specific proteins are secreted by mussels and used as a bioglue to stick to a surface. These mussel proteins present an unusual amino acid 3,4-dihydroxyphenylalanine (known as DOPA). The outstanding adhesive properties of these materials in the sea harsh conditions have been attributed to the presence of the catechol groups present in DOPA. Inspired by the structure and composition of t...

Influence of electrospinning parameters on Poly(hydroxybutyrate) electrospun me...

Poly(hydroxybutyrate) (PHB) obtained from sugar cane was dissolved in a blend of chloroform and dimethylformamide (DMF) and electrospun at 40 ºC. By adding DMF to the solution, the electrospinning process for the PHB polymer becomes more stable, allowing complete polymer crystallization during the jet travelling between the tip and the grounded collector. The influence of processing parameters on fiber size and...

Processing and characterization of alpha-elastin electrospun membranes

Elastin isolated from fresh bovine ligaments was dissolved in a mixture of 1,1,1,3,3,3-Hexafluoro-2-propanol and water and electrospun into fiber membranes under different processing conditions. Fiber mats of randomly and aligned fibers were obtained with fixed and rotating ground collectors and fibrils were composed by thin ribbons whose width depends on electrospinning conditions; fibrils with 721 nm up to 2....

Polymeric layer-by-layer films composed by natural polymers and based on the ad...

Publicado em "Journal of Tissue Engineering and Regenerative Medicine", vol. 7, supp. 1 (2013) ; Some marine species, such as mussels, can strongly attach themselves to rocks in the diffficult conditions of the sea. In fact, marine mussels secrete adhesive proteins that show a high adhesion to both inorganic and organic surfaces in aqueous environments. These proteins have an amino acid designated as 3,4-dihyd...

Physical-chemical properties of cross-linked chitosan electrospun fiber mats

Chitosan fiber mats were successfully processed by electrospinning. The as-spun fiber mats were neutralized with ethanol and cross-linked with glutaraldehyde. A decrease of the fiber average diameter from 243 ± 43 nm down to 215.53 nm was observed for the neutralized and cross-linking chitosan membrane. It was found that the processing conditions do not alter the initial deacetylation degree of the polymer. Pol...

Determination of the parameters affecting electrospun chitosan fiber size distr...

The production of chitosan nanofiber mats by electrospinning presents serious difficulties due to the lack of suitable solvents and the strong influence of processing parameters on the fiber properties. Two are the main problems to be solved: to control the properties of the solution in order to obtain large area uniform fiber mats by having a stable flow rate and to avoid sparks during the process, dam...

Science image in Portugal : studying high school students

In the development of activities for the dissemination of science and scientific work there are difficulties and challenges. People get in touch with science in different contexts, as in their workplace or their social life. However, it is in school that the largest number of interaction activities occurs, through communication and education practices. And high school is probably a key context to the promotion ...

Effect of weathering conditions on the degradation behaviour of ABS

UV stability of biobased copolymers

Tailoring porous structure of ferroelectric poly(vinylidene fluoride-trifluoroe...

Ferroelectric macroporous poly(vinylidene fluoride-trifuoroethylene) membranes have been produced by isothermal crystallization from the solution at different temperatures starting from different diluted solutions of the co-polymer in dimethylformamide. In this way pore architecture, consisting in interconnected spherical pores can be obtained. The mechanism and kinetics of solvent evaporation was investigated ...