C. Lopes

Functional behaviour of TiO2 films doped with noble metals

To evaluate the effects of different concentrations of noble metal in a TiO2 matrix, different films of both Ag/TiO2 and Au/TiO2 systems were prepared. Mechanical and tribological characterisation was carried out to evaluate the coating response as a function of the noble metal composition and (micro)structure of the films. The overall set of results indicates that the amorphous films reveal better results than the crystalline ones. For the amorphous samples, the reduced Youngs modulus and the adhesion critical loads followed similar tendencies in both sets of films. Wear rates were similar for all samples except for the one with the highest silver content. To improve brittleness of TiO2 films, the results seem to indicate that a slight metal doping is preferred, and Au proved to be a better choice than Ag. In fact, the sample with the lowest Au content revealed a better mechanical behaviour than the pure TiO2 film.

Modulated IR radiometry for determining thermal properties and basic characteristics of titanium thin films

Titanium thin films of different thicknesses were prepared by direct current magnetron sputtering to study modulated infrared (IR) radiometry as a tool for analyzing film thickness. Thickness was varied by regularly increasing the deposition time, keeping all the other deposition parameters constant. The influence of film thickness on morphological, structural, and electrical properties of the titanium coatings also was investigated. The experimental results revealed a systematic grain growth with increasing film thickness, along with enhanced film crystallinity, which led to increased electrical conductivity. Using the results obtained by modulated IR radiometry, the thickness of each thin film was calculated. These thickness values were then compared with the coating thickness measurements obtained by scanning electron microscopy. The values confirmed the reliability of modulated IR radiometry as an analysis tool for thin films and coatings, and for determining thicknesses in the micrometer range, in particular.

Antibacterial effect and biocompatibility of a novel nanostructured ZnO-coated gutta-percha cone for improved endodontic treatment

This work explored a novel approach to enhance the antibacterial activity of commercial Gutta-percha (GP) cones, the most commonly used core filling materials used in endodontic treatment. The reported procedure involved an argon (Ar) plasma treatment (PT) of the GP cone surface, followed by the deposition of a ZnO thin film by magnetron sputtering. The resulting surfaces were evaluated for surface topography, antibacterial activity against Enterococcus faecalis and Staphylococcus aureus, and cytocompatibility with human osteoblastic cells. GP cones treated with NaOCl, a routine chair-side protocol, were also tested as reference. The deposition of a ZnO film on pristine GP cones increased its antibacterial activity. Cones pre-treated with Ar-plasma (PT) and coated with the ZnO thin film presented significantly higher antibacterial activity than that observed on the pristine and, also, compared to the ZnO coated cones. The higher antibacterial activity of PT + ZnO cones appears related to the major effects induced by the PT pre-treatment on the cone surface endowing the deposited ZnO film with a homogeneous nanostructured topography that greatly improved surface reactivity. The modified GP cones maintained an appropriate cytocompatibility with human cells. This novel approach provides ready-to-use cones with enhanced antibacterial activity, improving a strict asepsis protocol during endodontic treatment and preventing secondary endodontic infections.

Effectiveness of SCRUM in Project Based Learning: Students View

Project and team management play a major role in the student team’s project performance. This is more evident when projects last a long time and the teams are large. In this work, a student team accepted to use SCRUM as their project management methodology during their Project Based Learning (PjBL) experience. This PjBL experience took place on the 7th semester of the Integrated Master in Industrial Engineering and Management degree. The team had a short period of time to train the technique and apply it throughout the entire semester. Although not very enthusiastic in the beginning of the project, the team gradually became aware of the advantages of SCRUM features, recognizing the feeling of having the project under control and gaining management effectiveness throughout the semester. In the end, the team performed well above the average, being one of the two teams with the highest score of the class.