Joana Vaz Pinto

Thin films of titanium dioxide (TiO2) and titanium (Ti) were deposited onto glass and optical fiber supports through DC magnetron sputtering, and their transmission was characterized with regard to their use in optical fiber-based sensors. Deposition parameters such as oxygen partial pressure, working pressure, and sputtering power were optimized to attain films with a high reflectance. The films deposited on glass supports were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Regarding the deposition parameters, all three parameters were tested simultaneously, changing the working pressure, the sputtering power, and the oxygen percentage. It was possible to conclude that a lower working pressure and higher applied power lead to films with a higher reflectance. Through the analysis of the as-sputtered thin films using X-ray diffraction, the deposition of both Ti and TiO2 films was confirmed. To study the applicability of TiO2 and Ti in fiber sensing, several thin films were deposited in single mode fibers (SMFs) using the sputtering conditions that revealed the most promising results in the glass supports. The sputtered TiO2 and Ti thin films were used as mirrors to increase the visibility of a low-finesse Fabry–Perot cavity and the possible sensing applications were studied.

© 2017 Elsevier Ltd. Graphical abstract: The electrochemical reduction of carbon dioxide dissolved in a solution of water and ionic liquid as electrolyte, at high-pressure and near room-temperature, is reported. This work describes an electro-deposition strategy for the preparation of copper substrate cathodes, coated with bimetallic zinc-copper films, obtained from deep-eutectic solvents plating baths. The prepared bimetallic cathodes showed electrochemical activity for syngas production in 1-butyl-3-methylimidazolium triflate, with yields of 85N$μ$L (normal microliter)cm−2C−1/170N$μ$Lcm−2h−1, high selectivities, tunable H2/CO ratio and low energetic requirements.

abstract Vermilion red, mercury sulphide (a-HgS), was one of the most important reds in art and its use as a pigment dates back to Antiquity. In medieval Europe, it could be mined as cinnabar, or produced as vermilion by heating mercury with sulphur. This work aims to study the production of synthetic vermilion as a medieval pigment and to confirm which was the source (mineral or artificial) of the reds used in Portuguese medieval illuminations. The production of synthetic vermilion was based on the process described in the Judaeo-Portuguese medieval treatise “The book on how to make colours”, using materials and technologies as close as possible to the medieval ones. The reaction mechanism was studied by following the heating process by X-ray diffraction, and it was possible to conclude that the transformation from black cubic b-HgS into red hexagonal a-HgS is a solid-state phase transition, occurring at 235 ?C. This result is contrary to what published in technical art literature, in which this process is described as a sublimation. Moreover, Scanning Electron Microscopy evidenced a sinterization effect on the artificial vermilion, not found in medieval original samples nor in paints prepared with mineral cinnabar from Almadén (Spain). Red mercury sulphide, natural and synthetic,was then prepared as a parchment-glue paint and compared to proteinaceous red paints from 12the13th century minia- tures produced in important medieval monasteries, previously fully characterized by a multi-analytical approach (m-Energy dispersive X-ray fluorescence, m-Fourier Transform Infrared Spectroscopy, Raman microscopy). A comparative Electron probe microanalysis of the red paints point to amineral provenance for medieval vermilion found in Portuguese illuminations

Vermilion red, mercury sulphide ($\alpha$-HgS), was one of the most important reds in art and its use as a pigment dates back to Antiquity. In medieval Europe, it could be mined as cinnabar, or produced as vermilion by heating mercury with sulphur. This work aims to study the production of synthetic vermilion as a medieval pigment and to confirm which was the source (mineral or artificial) of the reds used in Portuguese medieval illuminations. The production of synthetic vermilion was based on the process described in the Judaeo-Portuguese medieval treatise "The book on how to make colours", using materials and technologies as close as possible to the medieval ones. The reaction mechanism was studied by following the heating process by X-ray diffraction, and it was possible to conclude that the transformation from black cubic $\beta$-HgS into red hexagonal $\alpha$-HgS is a solid-state phase transition, occurring at 235 C. This result is contrary to what published in technical art literature, in which this process is described as a sublimation. Moreover, Scanning Electron Microscopy evidenced a sinterization effect on the artificial vermilion, not found in medieval original samples nor in paints prepared with mineral cinnabar from Almadén (Spain). Red mercury sulphide, natural and synthetic, was then prepared as a parchment-glue paint and compared to proteinaceous red paints from 12th-13th century miniatures produced in important medieval monasteries, previously fully characterized by a multi-analytical approach ($μ$-Energy dispersive X-ray fluorescence, $μ$-Fourier Transform Infrared Spectroscopy, Raman microscopy). A comparative Electron probe microanalysis of the red paints point to a mineral provenance for medieval vermilion found in Portuguese illuminations. © 2013 Elsevier Ltd. All rights reserved.

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Next-generation electrical nanoimprinting of a polymeric data sheet based on charge trapping phenomena is reported here. Carbon nanoparticles (CNPs) (waste carbon product) are deployed into a polymeric matrix (polyaniline) (PANI) as a charge trapping layer. The data are recorded on the CNPs-filled polyaniline device layer by “electro-typing” under a voltage pulse (VET, from ±1 to ±7 V), which is applied to the device layer through a localized charge-injection method. The core idea of this device is to make an electrical image through the charge trapping mechanism, which can be “read” further by the subsequent electrical mapping. The density of stored charges at the carbon–polyaniline layer, near the metal/polymer interface, is found to depend on the voltage amplitude, i.e., the number of injected charge carriers. The relaxation of the stored charges is studied by different probe voltages and for different devices, depending on the percolation of the CNPs into the PANI. The polymeric data sheet retains the recorded data for more than 6 h, which can be refreshed or erased at will. Also, a write–read–erase–read cycle is performed for the smallest “bit” of stored information through a single contact between the probe and the device layer.