CDRsp - Comunicações em conferências internacionais
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- Reinforced PCL scaffolds with Eggshell powderPublication . Biscaia, S. I.; Viana, T.F.; Almeida, H.A.; Bártolo, P.Hen eggshells (ES), a natural biomaterial from bone-like minerals, has been considered a promising bone substitute to be totally resorbable and biocompatible with good osteoconductivity. The ES represents 11% of the total weight of the egg and it is mainly composed of calcium carbonate (94%), magnesium carbonate (1%), tricalcium phosphate (1%), and organic matter (4%). The purpose of this study was to investigate the addition of ES powder on poly(ε.-caprolactone) (PCL) scaffolds. Morphological and physical analyses were performed to investigate the influence of the ES powder on the properties of the PCL scaffolds.
- The interaction between intra-stride variation of the velocity and mean race walking velocityPublication . Morouço, P.G.; Barbosa, T.Introduction The intra-stride/cycle variation of body velocity (dv) is considered as an estimator of the energy cost of locomo-tion or efficiency in some forms of human locomotion, including waking, running, trotting and swimming (1, 2). Previous studies reported nonlinear relationships between dv and velocity (v) for land and aquatic locomotion tech-niques (2,3). The aim of this study was to examine possible relationships between the dv and the v in race walking.
- The Impact of the Employer's Brand Image on Knowledge SharingPublication . Espírito Santo, Pedro Manuel do; Ferreira, Vítor Hugo Santos; Marques, Alzira Maria AscensãoKnowledge Sharing is a key driver of firm performance, but it relies on firm’s ability of retaining its most capable human resources and creating workercentered environments to encourage the open sharing and use of all forms of knowledge. Attracting the right people through brand image and creating the conditions for employees to live the company in a passionate way, with high trust and commitment (with high team cohesion), will lead to a more long-term orientation thus allowing for increased Knowledge sharing (tacit and explicit). Through a case-study based approach, using data from a Portuguese company with 302 employees, we analyzed the impact of the employer's brand image on knowledge sharing mediated by team cohesion and long-term employee orientation. The results of the model tested through PLS-SEM showed that brand image produces effects on knowledge sharing. These effects are mediated through the decisive role of team cohesion.
- Fused Deposition of WC+Co powderPublication . Cerejo, F.; Raimundo, A. M.; Vieira, M. T.; Barreiros, FatimaAdditive manufacturing (AM) of WC-Co is a great challenge. Up to now, powder bed fusion reveals enormous problems for WC-Co. New techniques are necessary to enlarge AM to hard materials. Based on feedstock developed for injection of metallic and ceramic powders (MIM/CIM) it was possible to extrude WC-Co filaments with success. This study is focused on development filaments based on WC-Co (d50=8 µm) to be applied in fused deposition modelling additive process, but assuming the acronym of FDC, to highlight that powder is a ceramic (C). Thus, it was evaluated the critical powder volume concentration (CPVC) of WC-Co in feedstock specially developed to fulfil the filament characteristics need. Different binder system (master + backbone+ additive) were tested. Parts were printed through a filament with 48.5 (vol.%) of WC-10Co. A suitable selection of thermal parameters for debinding and sintering has led to guarantee geometry and mechanical properties required for the part. © European Powder Metallurgy Association (EPMA)
- Adhesion, proliferation and distribution of human mesenchymal stem/stromal cells (MSCs) in Poly(ɛ -caprolactone) (PCL) scaffolds with different pore sizesPublication . Moura, C. S.; Biscaia, S.; Viana, T.; Bártolo, P. J.; Silva, C. L. da; Cabral, J. S.; Ferreira, F. C.Tissue engineering, combining the use of biomaterials, mesenchymal stem/stromal cells (MSCs) and optimized culture medium formulations, is a very promising research field for tissue regeneration. This work is focused on the application of Poly(ε-caprolactone) scaffolds designed to have a spacing gradient between orthogonal fibres with diameters of 0.3mm with pore sizes ranging from 190 to 390 μm. Human bone marrow (BM)-derived MSCs, were used to evaluate cell adhesion, proliferation and distribution within the scaffolds. Specifically, we hypothesized if seeding MSC in scaffold regions with different pore sizes would influence cell proliferation. Therefore, MSC were seeded at the centre of scaffolds with either larger (390 μm) or smaller pores (190 μm). Results obtained showed similar levels of adhesion and proliferation in both configurations, with fold increase in total cell number of 5 after 13 days of cultivation; which indicates that no limitation for cell proliferation within the range of pore sizes studied is observed.
- 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%).
- BioFab toolbox – Software tools for biofabricationPublication . Alves, N.; Bártolo, P.; Ferreira, N.; Gaspar, M.; Mateus, A.This is a progress report of a project called BioFab Toolbox, funded by the Portuguese National Science Foundation, consisting of the development of a collection of software tools to assist in the process of rapid prototyping and rapid manufacturing of new products. This project is especially designed to produce scaffolds, grafts, implants and other medical applications usually designated as biofabrication (biofab).
- Direct writing of conductive polymer tracks as part of an additive manufacturing processPublication . Mitchell, G. R.; Davis, Fred J.The use of electrically conductive polymers to construct hetereogenous structures via additive manufacturing is an attractive possibility. It maintains the all polymeric nature of such structures. In this work we discuss how this might be achieved in practical additive manufacturing equipment.
- Structure development during additive manufacturingPublication . Tojeira, A.; Biscaia, S.; Viana, T.; Bártolo, P. J.; Mitchell, G. R.Additive manufacturing involves the shaping of a product through the use of a liquid phase which is subsequently transformed to the solid state by cooling or through the use of chemical cross-linking reactions. Of particular note is the fused deposition modeling which utilizes semi-crystalline polymers such as poly(ε-caprolactone) or poly(lactic acid) and has been employed in CDRsp to prepare highly porous scaffolds for Tissue Engineering. We show that the crystallization process amplifies small levels of molecular anisotropy introduced in the additive writing process. We show that the level of anisotropy is significantly dependent on the process parameters such as temperature, write speed, and flow rate. The differences in the crystalline morphology introduced by changing these process parameters will have a marked impact on the mechanical properties. This in turn will alter the growth of tissue on such scaffold structures. As with other polymer processing procedures, tuning the process parameters provides a route to controlling and defining the structure and morphology of the scaffold and the properties exhibited by that scaffold.
- Innovative developments on Agile-CAD systemPublication . Gaspar, M.; Alves, N.; Martins-Ferreira, N.; Bártolo, P.Agile-CAD is a reverse engineering computer tool that allows the recovering of outer and inner 3D shapes of existing objects of revolution with constant thickness, using silhouettes computed from one or two digital views. In this context, some improved algorithms were developed in order to provide more accurate and robust tridimensional reconstruction when using a single digital image as source. Experimental results based on real images are presented, demonstrating the good performance of this computer tool.