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Publications

Publications by CAP

2020

Surface Plasmon Resonance sensor based on a D-shaped photonic crystal fiber with a bimetallic layer

Authors
Cardoso, MP; Silva, AO; Romeiro, AF; Giraldi, MTR; Costa, JC; Santos, JL; Baptista, JM; Guerreiro, A;

Publication
EPJ Web of Conferences

Abstract
The investigation of a D-shaped photonic crystal fiber sensor with a bimetallic layer for operation at the visible and infrared spectra is presented. The bimetallic layer is composed by silver and gold slabs deposited adjacently on the flat face of the fiber. It is shown that this architecture allows the excitation of two sharply distinguished plasmon resonance, which suggest potential applications for multiparameter sensing.

2020

Behavior of Listeria monocytogenes in beef Sous vide cooking with Salvia officinalis L. essential oil, during storage at different temperatures

Authors
Moura Alves, M; Gouveia, AR; de Almeida, JMMM; Monteiro Silva, F; Silva, JA; Saraiva, C;

Publication
LWT-FOOD SCIENCE AND TECHNOLOGY

Abstract
This study aims to evaluate the effect of Salvia officinalis L. (sage) essential oil (EO) on behavior of L. monocytogenes ATCC679 inoculated in beef processed by Sous-vide cook-chill (SVCC) and stored at 2 or 8 degrees C during 28 days. Minimum inhibitory concentration (MIC) of L. monocytogenes was obtained with 31.3 mu L/mL of EO. D values were determined for samples with EO (21'39 '') and without EO (21'17 ''). Beef samples were inoculated with L. monocytogenes at a concentration of 1 x 108 CFU/mL and vacuum-packed after EO addition at MIC value. Three heat treatments (F) were applied to reduce 1-log10 (F1), 2-log10 (F2) and 3-log10 (F3). EO composition was identified by gas-chromatography mass-spectrometry analysis. The main compounds identified were beta-pinene (11.70%), camphor (8.21%), beta-thujene (7.82%), 1.8-cineole (5.19%), alpha-humulene (6.07%) and endoborneol (4.87%).A reduction of approximately 1 log (CFU/g) of L. monocytogenes was observed in EO samples, compared to control samples at 2 degrees C. At 8 degrees C, despite exponential development from day 14, lower L. monocytogenes counts were observed in EO samples. Data showed that sage EO can help to control L. monocytogenes growth. However a possibility of using sage as a natural preservative, must be combined with other agents to control microbial growth more effectively.

2020

Magnetostriction in Amorphous Co66Fe34 Microcantilevers Fabricated with Hydrogenated Amorphous Silicon

Authors
Silveira, B; Belo, J; Pinto, R; Silva, J; Ferreira, T; Pires, A; Chu, V; Conde, J; Frazão, O; Pereira, A;

Publication
EPJ Web of Conferences

Abstract
To study the magnetostriction of Co66Fe34 thin films, amorphous silicon microcantilevers were prepared by surface micromachining, and the 136 nm-thick magnetostrictive film was deposited by electron beam physical vapor deposition and patterned on top of the microcantilever structure. The magnetostriction of the Co66Fe34 films was confirmed by measuring the deflection of the cantilevers under a varying magnetic field, reaching displacements up to 8 nm. The configuration was simulated using COMSOL software, yielding a similar deflection behavior as a function of the magnetic field, with a film with a magneto strictive coefficient of ? S ~ 55 p.p.m. The experimental configuration uses a laser and a position sensitive detector to measure the displacement, based on an optical lever configuration, and a piezoelectric stage to calibrate the system.

2020

WiPTherm: Hybrid power harvesting system for a 3U CubeSat

Authors
Agelet, FA; Darau, VD; Camanzo, A; Luis, UG; Orgeira Crespo, P; Navarro Medina, F; Luis, UG; Ulloa, C; Botelho, V; Hallak, Y; Pires, AL; Maia, MM; Pereira, AM; Silva, J; Ribeiro, M; Machado, V; Pimenta, J; Silva, S; California, A; Leconte, B; Jamier, R; Auguste, JL; Roy, P; Robalinho, P; Frazão, O;

Publication
Proceedings of the International Astronautical Congress, IAC

Abstract
CubeSats are becoming an alternative challenge for space exploration. Research in the technology and applicability of these small platforms has received an increasing interest in the last years. They represent an emergent technological market (CAGR growth of 37.91 % in the 2017-2021 period), while a variety of fields like meteorology, climatic research, transportation safety, or navigation is resorting to this technology. As more complex CubeSats missions are defined, a natural increase in the mission power demand occurs. In a scarce-resource environment like the space, this demands the development of new ways of harvesting spacecraft electrical energy. An alternative to traditional energy harvesting systems composed of solar panels and batteries is Wireless Energy Transfer (WET). It originates in the electromagnetic transfer, proven to have two important limitations: high power efficiency decrease at distances bigger than coil size and the need of mobile parts. A new approach is proposed as a solution to these limitations: the possibility of mounting on a 3U CubeSat photo-thermoelectric generator array devices that can convert photon energy to electrical energy via thermal gradient generation. For creating the thermal gradient, a long-range laser source targets cells from each array forming the hybrid photo-thermoelectric plasmonic system (HPTP). Two possible scenarios are presented in terms of mission requirements and analysis: a controlled pulsed large-range laser source located on Earth, in the case of Earth-orbiting missions, or on a hub system, in a deep-space mission. For Earth, Mars and Jupiter, a simulation of the total energy produced by solar panels and the HPTP system is presented to illustrate the potential use of the WiPTherm technology. In each of the scenarios, key measures of effectiveness will be analysed to overcome potential CubeSat and constituent subsystems overheat, by comparison with nominal component and shield temperature profiles in both eclipse and illuminated cases when the HPTP system is not used. Pointing budget accuracy and jitter for targeting the HPTP generator cells and required laser link budget for a planned energy transfer efficiency of up to 10 % of the source power are other challenges covered in the presentation, apart from research topics from a multidisciplinary group covering nanomaterials science, optics, photonics, and CubeSats power systems engineering. Copyright

2020

New Material Concepts

Authors
Nunes, JP; Costa, AJ; Rodrigues, DSS; Covas, JA; Viana, JC; Pontes, AJ; Duarte, FM; Fernandes, FMB; Camacho, E; Santos, TG; Inácio, PL; Nascimento, M; Paixão, T; Novais, S; Pinto, JL;

Publication
Advanced Structured Materials

Abstract
This chapter focuses on new compositions of thermoplastic matrices and reinforcements to process by fused deposition modelling (FDM). The available materials for this additive manufacturing (AM) technique are generally limited to PLA—polylactic acid, ABS—acrylonitrile butadiene styrene and PA—polyamide (NYLON®) with temperature gradients and mechanical behaviours that are not suited for high-performance applications, such as aeronautics and automotive sector. In this work, an intensive research was made in order to evaluate mechanical, thermal and rheological properties considered important for 3D printing of commercial filaments. Results aided in the selection of high-performance reinforced materials for AM. Advanced polymers, such as PEEK—polyether ether ketone and PA66—polyamide 66, were the matrices chosen to produce high service nanocomposite formulations, each with varying amounts of multi-wall carbon nanotubes (MWCNTs). The resulting feedstock materials were characterized using the same techniques as the commercial filaments. Preliminary tests with printed parts of these composites were made in pursuance of their optimal printing parameters to undergo an experimental hybrid system (EHS). © 2020, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.

2020

Reliability and NDT Methods

Authors
Santos, TG; Oliveira, JP; Machado, MA; Inácio, PL; Duarte, VR; Rodrigues, TA; Santos, RA; Simão, C; Carvalho, M; Martins, A; Nascimento, M; Novais, S; Ferreira, MS; Pinto, JL; Fernandes, FB; Camacho, E; Viana, J; Miranda, RM;

Publication
Advanced Structured Materials

Abstract
Composites are finding increased use in structural high demanding and high added value applications in advanced industries. A wide diversity exists in terms of matrix type, which can be either polymeric or metallic and type of reinforcements (ceramic, polymeric or metallic). Several technologies have been used to produce these composites; among them, additive manufacturing (AM) is currently being applied. In structural applications, the presence of defects due to fabrication is of major concern, since it affects the performance of a component with negative impact, which can affect, ultimately, human lives. Thus, the detection of defects is highly important, not only surface defects but also barely visible defects. This chapter describes the main types of defects expected in composites produced by AM. The fundamentals of different non-destructive testing (NDT) techniques are briefly discussed, as well as the state of the art of numerical simulation for several NDT techniques. A multiparametric and customized inspection system was developed based on the combination of innovative techniques in modelling and testing. Experimental validation with eddy currents, ultrasounds, X-ray and thermography is presented and analysed, as well as integration of distinctive techniques and 3D scanning characterization. © 2020, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.

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