Browsing by Author "Teixeira, H."
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- Effect of albumin, urea, lysozyme and mucin on the triboactivity of Ti6Al4V/zirconia pair used in dental implantsPublication . Teixeira, H.; Branco, A. C.; Rodrigues, I.; Silva, D.; Cardoso, S.; Colaço, R.; Serro, A. P.; Figueiredo-Pina, CélioThe titanium implant/zirconia abutment interface can suffer failure upon mechanical and biological issues, ul- timately leading to the loss of the artificial tooth. The study of the effect of the organic compounds present in saliva on the tribological behavior of these systems is of utmost importance to understand the failure mechanisms and better mimic the in vivo conditions. The aim of the present work is to evaluate the effect of the addition of albumin, urea, lysozyme and mucin to artificial saliva, on the triboactivity of Ti6Al4V/zirconia pair commonly used in dental implants and then, compare the results with those obtained with human saliva. The solutions’ viscosity was measured and the adsorption of the different biomolecules to both Ti6Al4V and zirconia was accessed. Tribological tests were performed using Ti6Al4V balls sliding on zirconia plates inside of a corrosion cell. Friction and wear coefficients were determined, and the open circuit potential (OCP) was monitored during the tests. Also, the wear mechanisms were identified. The presence of mucin in the artificial lubricant led to the lowest wear coefficients. The main wear mechanism was abrasion, independently of the used lubricant. Adhesive wear was observed for the systems without mucin. Tribocorrosion activity and wear coefficient were lower in the presence of mucin. None of the studied artificial lubricants mimicked the effect of human saliva (HS) on the tribological behavior of the studied pair since this lubricant led to the lowest friction coefficient and highest corrosion activity.
- Effect of the saliva biomolecules on the interface zirconia/Ti6Al4V triboactivityPublication . Teixeira, H.; Serro, A. P.; Figueiredo-Pina, C. G.
- Greenhouse microclimate real-time monitoring based on wireless sensor network and gisPublication . Postolache, Octavian; Girão, Pedro; Pereira, José Miguel Costa Dias; Grueau, C.; Teixeira, H.; Leal, M.The usage of greenhouse with controlled microclimate represents an important way to increase the production of fruits and vegetables considering the plants needs and has recently become one of the hottest topics in precision agriculture. In order to know and to control the greenhouse microclimate smart sensing nodes with wireless communication capabilities represents the solution. As one of promissory protocol associated with wireless sensor network can be mentioned the ZigBee due to its low cost, low power consumption, extended ranges and architecture flexibility. In the present work a sensing and control sensing nodes with ZigBee communication capabilities are considered, while the microclimate is monitored using a set of solid state sensors for temperature, relative humidity, light intensity and CO2 concentration considering this parameters with important role in plants growing. Every sensor node uses energy from a solar cell through a battery charger circuit considering also the powering of the sensing and control node during the night periods. The data from ZigBee network nodes are sent to Wireless-Ethernet gateway connected to a computer that runs a LabVIEW application that perform primary processing and web geographic information system that provides information about the greenhouse microclimate. Elements related power harvesting for implemented wireless sensor network, as so as a set of experimental results are included in the present work.