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Publicações

Publicações por Daniel Alexandre

2015

Wine fingerprinting using a bio-geochemical approach

Autores
Fernandes, JR; Pereira, L; Jorge, P; Moreira, L; Goncalves, H; Coelho, L; Alexandre, D; Eiras Dias, J; Brazao, J; Climaco, P; Baleiras Couto, M; Catarino, S; Graca, A; Martins Lopes, P;

Publicação
38TH WORLD CONGRESS OF VINE AND WINE (PART 1)

Abstract
The wine sector is a billion euro business and therefore subjected to multiple attempts of fraudulent practices. This requires the development of rapid and reliable methods to detect such situations. Several methodologies have been developed based on the chemical profiles of the wines, but they are limited due to the environmental conditions that cannot be controlled. The use of DNA-based detection systems are an emergent research field that have been extended to a wide variety of food products and are still the most reliable methods for varietal identification. However these methods are not suitable for geographical determination. Soil related fingerprints have a primary role considering that there is a relationship between the elemental composition of wine and the composition of the provenance soil. WineBioCode is a project aiming to define the best strategy for wine authenticity based on a multidisciplinary approach. Two DNA-based strategies have been developed based on Real-time PCR and a label free optical biosensor platform. Both platforms enabled successful identification of specific DNA-targets when applied to Vitis vinifera L., and can be applied throughout the grape-wine chain. The methods are complementary and can be used in different situations, according to the requirements. The geographical evaluation has been assessed by the strontium 875r1865r isotope ratio determination involving soil evaluation in the vineyards followed by its assay in the wine samples. The results are being integrated in order to establish the best procedure to be undertaken for wine fingerprinting, including varietal composition and geographical origin, therefore fulfilling the requirements of the geographical denominations in wine certification.

2017

Monolithic Add-Drop Multiplexers in Fused Silica Fabricated by Femtosecond Laser Direct Writing

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

Publicação
JOURNAL OF LIGHTWAVE TECHNOLOGY

Abstract
The fabrication of optical add-drop multiplexers in fused silica is demonstrated, for the first time to our knowledge, using the femtosecond laser direct writing technique. To achieve this, a Mach-Zehnder interferometer configuration was used for the signal routing by the implementation of 3-dB directional couplers, along with Bragg grating waveguides for wavelength selectivity. The fabrication of all individual devices required was optimized. The behavior of the fabricated add-drop multiplexer was characterized at around 1550 nm, where a 3-dB bandwidth of 0.19 +/- 0.01 nm was obtained along with an intrachannel and adjacent interchannel crosstalk of -30 and -20 dB at Delta lambda = +/- 0.75 nm, respectively. This study shows that such complex devices can be manufactured by femtosecond laser direct writing, with future improvements being discussed.

2014

High Speed All Optical Logic Operations Utilizing the Protein Bacteriorhodopsin

Autores
Fabian, L; Mathesz, A; Valkai, S; Alexandre, D; Marques, PVS; Ormos, P; Wolff, EK; Der, A;

Publicação
BIOPHYSICAL JOURNAL

Abstract

2013

Protein-based high-speed all-optical logic

Autores
Mathesz, A; Fabian, L; Valkai, S; Alexandre, D; Marques, PVS; Wolff, EK; Ormos, P; Der, A;

Publicação
EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS

Abstract

2014

High Speed All Optical Logic Operations Utilizing the Protein Bacteriorhodopsin

Autores
Fábián, L; Mathesz, A; Valkai, S; Alexandre, D; Marques, PV; Ormos, P; Wolff, EK; Dér, A;

Publicação
Biophysical Journal

Abstract

2018

Fabrication of Monolithic Add-Drop Filters in Pure Silica by Femtosecond Laser Writing

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

Publicação
2018 20TH ANNIVERSARY INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON)

Abstract
This paper will review the fabrication of monolithic integrated optical devices by laser direct writing with femtosecond pulsed laser sources, starting with the description of experimental procedures and optimal conditions to fabricate low loss optical waveguides, directional couplers, Y-junctions and first order Bragg gratings by point-by-point writing methods. Finally, the characterization results of a fully operational Add-Drop filter in pure fused silica substrate are described.

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