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Echeverria, C., P. Soares, A. Robalo, L. Pereira, C. M. M. Novo, I. Ferreira, and J. P. Borges, "One-pot synthesis of dual-stimuli responsive hybrid PNIPAAm-chitosan microgels", Mater. Des, vol. 86, pp. 745-751, 2015. AbstractDOI

The incorporation of magnetic nanoparticles into poly(N-isopropylacrylamide) (PNIPAAm) and chitosan microgels gives rise to hybrid systems that combine the microgels swelling capacity with the interesting features presented in magnetic nanoparticles. The presence of chitosan that act as surfactant for magnetic nanoparticles provides a simplistic approach which allows the encapsulation of magnetic nanoparticles without any previous surface modification. Spherical and highly monodisperse microgels with diameters in the range of 200 to 500 nm were obtained. The encapsulation of magnetic nanoparticles in the polymer matrix was confirmed by high resolution Scanning Electron Microscopy in transmission mode. Volume phase transition of the microgels was accessed by Dynamic Light Scattering measurements. It was observed that the thermosensitivity of the PNIPAM microgels still persists in the hybrid microgels; however, the swelling ability is compromised in the microgels with highest chitosan content. The heating performance of the hybrid magnetic microgels, when submitted to an alternating magnetic field, was also evaluated demonstrating the potential of these systems for hyperthermia treatments.

Figueira, J., J. Loureiro, J. Marques, C. Bianchi, P. Duarte, M. Ruoho, I. Tittonen, and I. Ferreira, "Optimization of Cuprous Oxides Thin Films to be used as Thermoelectric Touch Detectors", ACS Appl Mater Interfaces, vol. 9, issue 7, pp. 6520-6529, 2017. AbstractDOI

The electronic and optical properties of p-type copper oxides (CO) strongly depend on the production technique as it influences the obtained phases: cuprous oxide (Cu2O) or cupric oxide (CuO), the most common ones. Cu films deposited by thermal evaporation have been annealed in air atmosphere, with temperature between 225 and 375 °C and time between 1 and 4 h. The resultant CO films have been studied to understand the influence of processing parameters in the thermoelectric, electrical, optical, morphological, and structural properties. Films with a Cu2O single phase are formed when annealing at 225 °C, while CuO single phase films can be obtained at 375 °C. In between, both phases are obtained in proportions that depend on the film thickness and annealing time. The positive sign of the Seebeck coefficient (S), measured at room temperature (RT), confirms the p-type behavior of both oxides, showing values up to 1.2 mV·°C–1and conductivity up to 2.9 (Ω·m)−1. A simple detector using Cu2O have been fabricated and tested with fast finger touch events

Castro, D., P. Jaeger, A. C. Baptista, and J. P. Oliveira, "An Overview of High-Entropy Alloys as Biomaterials", Metals, vol. 11, pp. 648, 2021.