Articles by Gregory J. Gibbons in JoVE
Inkjet-printed Polyvinyl Alcohol Multilayers Iulia Salaoru1,2, Zuoxin Zhou2, Peter Morris3, Gregory J. Gibbons2 1Emerging Technologies Research Centre (EMTERC), De Montfort University, 2WMG, University of Warwick, 3PVOH Polymer Ltd. An inkjet printer was used to manufacture polyvinyl alcohol multilayers. Polyvinyl alcohol water-based ink was formulated, and the main physical properties were investigated.
Other articles by Gregory J. Gibbons on PubMed
3D Printing of Porous Hydroxyapatite Scaffolds Intended for Use in Bone Tissue Engineering Applications Materials Science & Engineering. C, Materials for Biological Applications. Feb, 2015 | Pubmed ID: 25492194 A systematic characterisation of bone tissue scaffolds fabricated via 3D printing from hydroxyapatite (HA) and poly(vinyl)alcohol (PVOH) composite powders is presented. Flowability of HA:PVOH precursor materials was observed to affect mechanical stability, microstructure and porosity of 3D printed scaffolds. Anisotropic behaviour of constructs and part failure at the boundaries of interlayer bonds was highlighted by compressive strength testing. A trade-off between the ability to facilitate removal of PVOH thermal degradation products during sintering and the compressive strength of green parts was revealed. The ultimate compressive strength of 55% porous green scaffolds printed along the Y-axis and dried in a vacuum oven for 6h was 0.88 ± 0.02 MPa. Critically, the pores of 3D printed constructs could be user designed, ensuring bulk interconnectivity, and the imperfect packing of powder particles created an inherent surface roughness and non-designed porosity within the scaffold. These features are considered promising since they are known to facilitate osteoconduction and osteointegration in-vivo. Characterisation techniques utilised in this study include two funnel flow tests, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), compressive strength testing and computed tomography (CT).
Modelling the Penumbra in Computed Tomography1 Journal of X-ray Science and Technology. May, 2016 | Pubmed ID: 27232198 In computed tomography (CT), the spot geometry is one of the main sources of error in CT images. Since X-rays do not arise from a point source, artefacts are produced. In particular there is a penumbra effect, leading to poorly defined edges within a reconstructed volume. Penumbra models can be simulated given a fixed spot geometry and the known experimental setup.