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 2.12 m width were achieved. After cross-linking with glutaraldehyde, -elastin can uptake as much as 1700 % of PBS solution and a slight increase on fiber thickness was observed. The glass transition temperature of electrospun fiber mats was found to occur at ~ 80 ºC. Moreover, -Elastin showed to be a perfect elastomeric material, and no mechanical hysteresis was found in cycle mechanical measurements. The elastic modulus obtained for oriented and random fibers mats in a PBS solution was 330 ± 10 kPa and 732 ± 165 kPa, respectively. Finally, the electrospinning and cross-linking process does not inhibit MC-3T3-E1 cell adhesion. Cell culture results showed good cell adhesion and proliferation in the cross-linked elastin fiber mats.

Effect of neutralization and cross-linking on the thermal degradation of chitosan electrospun membranes

Thermal degradation of as electrospun chitosan membranes and samples subsequently treated with ethanol and cross-linked with glutaraldehyde (GA) have been studied by thermogravimetry (TG) coupled with an infrared spectrometer (FTIR). The influence of the electrospinning process and cross-linking in the electrospun chitosan thermal stability was evaluated. Up to three degradation steps were observed in the TG data, corresponding to water dehydration reaction at temperatures below 100 ºC, loss of side groups formed between the amine groups of chitosan and trifluoroacetic acid between 150 – 270 ºC and chitosan thermal degradation that starts around 250 ºC and goes up to 400 ºC. The Kissinger model was employed to evaluate the activation energies of the electrospun membranes during isothermal experiments and revealed that thermal degradation activation energy increases for the samples processed by electrospinning and subsequent neutralization and cross-linking treatments with respect to the neat chitosan powder.

Instrumentos para la gestión de la empresa

En el actual escenario económico, caracterizado por su complejidad, globalización, volatilidad e incertidumbre, el éxito de las organizaciones, o al menos su supervivencia a largo plazo, depende de su capacidad de adaptación a las nuevas condiciones competitivas impuestas por el entorno, así como de su capacidad de reacción para adecuar sus fortalezas y debilidades al plan de actuación estratégico. Es necesario pues que el sistema de información de la empresa recoja y gestione la información que, por un lado, enfocada en cantidades monetarias, analice las actuaciones pasadas y permita la toma de decisiones a corto plazo y, por otro, aquella que permita recopilar datos sobre que pueden suponer una ventaja competitiva para la empresa y hacer de su gestión una fuente de riqueza a largo plazo. Para ello las empresas deben disponer y hacer uso de herramientas de gestión que le permitan la recopilación, el análisis y verificación de la información que ayude al logro de los objetivos a corto y largo plazo establecidos por la empresa.