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Publicações

Publicações por Daniel Alexandre

2019

Advances in Fs-Laser Micromachining Towards the Development of Optofluidic Devices

Autores
Maia, JM; Amorim, VA; Alexandre, D; Marques, PVS;

Publicação
OPTICS, PHOTONICS AND LASER TECHNOLOGY 2017

Abstract
In this chapter the developments made in femtosecond laser micromachining for applications in the fields of optofluidics and lab-on-a-chip devices are reviewed. This technology can be applied to a wide range of materials (glasses, crystals, polymers) and relies on a non-linear absorption process that leads to a permanent alteration of the material structure. This modification can induce, for instance, a smooth variation of the refractive index or generate etching selectivity, which can be used to form integrated optical circuits and microfluidic systems, respectively. Unlike conventional techniques, fs-laser micromachining offers a way to produce high-resolution three-dimensional components and integrate them in a monolithic approach. Recent advances made in two-photon polymerization have also enabled combination of polymeric structures with microfluidic channels, which can provide additional functionalities, such as fluid transport control. In particular, here it is emphasised the integration ofmicrofluidic systems with optical layers and polymeric structures for the fabrication of miniaturized hybrid devices for chemical synthesis and biosensing.

2021

Food Waste and Qualitative Evaluation of Menus in Public University Canteens-Challenges and Opportunities

Autores
Aires, C; Saraiva, C; Fontes, MC; Moreira, D; Moura Alves, M; Goncalves, C;

Publicação
FOODS

Abstract
Background: This study aims to evaluate food waste and menu quality in two canteens (A and B) from a Portuguese public university in order to identify challenges and opportunities to improve the food service. Methods: Food waste included the analysis of two canteens over 5 consecutive days by selective aggregate weighing. A qualitative evaluation of a 5-week menu cycle related to lunches was performed through the Qualitative Evaluation of Menus (AQE-d) method. Results: Both menus have "satisfactory " evaluations and lower adequacy to the dietary guidelines in criteria A, which evaluates general items from the dish, and in criteria B, which evaluates meat, fish and eggs. The calculated mean of food waste in both canteens exceeded the acceptable limit of 10%, except for the vegetarian (7.5%) dish in canteen A. The biggest waste was found in the vegetarian dish (16.8%) in canteen A. In meat dishes the conduit presents more waste (17.0%) than in fish and vegetarian dishes. Among these, the vegetables were the most wasted (25.3% and 27.9%, respectively). Conclusion: This work presents some insights to future interventions in the direction of a healthier and more sustainable foodservice.

2011

Fabrication of Planar Integrated Optic Devices by Laser Patterning

Autores
Marques, P; Alexandre, D; Ghasemphour, A; Moreira, P; Leite, A;

Publicação
Rapid Prototyping Technology - Principles and Functional Requirements

Abstract

2005

Photosensitive materials for integrated optic applications

Autores
Marques, PVS; Moreira, PJ; Alexandre, D; Melo, M; Schmidt, TEA; Muenzner, R; Leite, AMP; Aitchison, JS;

Publicação
FIBER AND INTEGRATED OPTICS

Abstract
This article presents results of device fabrication using UV processing of materials and integrated optic components produced by flame hydrolysis deposition and hybrid sol-gel technology. Photosensitive materials were employed in the fabrication of channel waveguides and channel photo-imprinted waveguides incorporating Bragg gratings through single and double-step exposure.

2010

Performance of astronomical beam combiner prototypes fabricated by hybrid sol-gel technology

Autores
Ghasempour, A; Leite, AMP; Alexandre, D; Reynaud, F; Marques, PVS; Garcia, PJV; Moreira, PJ;

Publicação
OPTICS EXPRESS

Abstract
Integrated optics coaxial two, three and four telescope beam combiners have been fabricated by hybrid sol-gel technology for astronomical applications. Temporal and spectral analyses of the output interferometric signal have been performed, and their results are in mutual good agreement. The results of the characterization method employed are cross-checked using contrast measurements obtained independently, demonstrating that the chromatic differential dispersion is the main contributer to contrast reduction. The mean visibility of the fabricated devices is always higher than 95 %, obtained using a source with spectral bandwidth of 50 nm. These results show the capability of hybrid sol-gel technology for fast prototyping of complex chip designs used in astronomical applications. (C) 2010 Optical Society of America

2009

Hybrid sol-gel planar optics for astronomy

Autores
Ghasempour, A; Leite, AMP; Reynaud, F; Marques, PVS; Garcia, PJV; Alexandre, D; Moreira, PJ;

Publicação
OPTICS EXPRESS

Abstract
Hybrid sol-gel planar optics devices for astronomy are produced for the first time. This material system can operate from the visible (0.5 mu m) up to the edge of astronomical J-band (1.4 mu m). The design, fabrication and characterization results of a coaxial three beam combiner are given as an example. Fringe contrasts above 94% are obtained with a source with spectral bandwidth of 50 nm. These results demonstrate that hybrid sol-gel technology can produce devices with high quality, opening the possibility of rapid prototyping of new designs and concepts for astronomical applications. (C) 2009 Optical Society of America

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