Percorrer por autor "Bartolo, Paulo J."
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- Computer modelling and simulation of a bioreactor for tissue engineeringPublication . Pereira, Rúben F.; Freitas, Dino; Tojeira, Ana; Almeida, Henrique A.; Alves, Nuno; Bartolo, Paulo J.A conventional approach to tissue engineering involves the implantation of porous, biodegradable and biocompatible scaffolds seeded with cells into the defect site. In some strategies, tissue engineering requires the in vitro culture of tissueengineering constructs for implantation later. In this case, bioreactors are used to grow 3D tissues under controlled and monitored conditions. However, the quality of the resulting 3D tissue is highly dependent on the design and dimensions of the bioreactor, as well on the operating conditions. In this work, a computational fluid dynamic software package was used to investigate the influence of cylindrical bioreactor dimensions (length and diameter) on the fluid flow and scaffold shear stress. Computer simulations were performed using three different rotational movements (horizontal, vertical and biaxial rotation) and appropriate boundary conditions. Results show that the effect of the bioreactor length on the scaffold shear stress is more important than the diameter, while high length is associated to low scaffold shear stress. On the other hand, the fluid flows within the bioreactor and scaffold shear stresses are dependent on the rotational movement, being more uniform in the biaxial rotation due to the combination of rotational movements.
- Materials characterization for stereolithographyPublication . Camaño, Patricia; Bartolo, Paulo J.Stereolithography is an additive technology that allows the fabrication of three-dimensional macro and micro-parts for industrial and medical applications. By solidifying a liquid photo-sensitive monomer with a laser or UV-light source a polymeric part is built up layer by layer. The use of highly reinforced polymeric systems with metallic or ceramic particles also enables to transform this rapid prototyping technology into a rapid manufacturing one. The quality and fabrication speed of stereolithographic parts strongly depends on the curing kinetics. Therefore it is crucial to optimize the polymeric mixture for a specific application. This research work investigates the curing kinetics of reinforced and non-reinforced unsaturated polyester resins with different photo-initiator concentrations. Two types of particles were considered: tungsten carbide and hydroxyapatite (concentrations of 30 wt%).