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Details

  • Nationality

    Portugal
  • Centre

    Applied Photonics
  • Contacts

    +351220402301
    helena.s.vasconcelos@inesctec.pt
001
Publications

2019

Mach-Zehnder Interferometers Based on Long Period Fiber Grating Coated with Titanium Dioxide for Refractive Index Sensing

Authors
Soares Guedes Vasconcelos, HCASG; Marques Martins de Almeida, JMMM; Teixeira Saraiva, CMT; da Silva Jorge, PAD; Costa Coelho, LCC;

Publication
Journal of Lightwave Technology

Abstract

2018

Plasmonic Optical Fiber Sensor Based on Double Step Growth of Gold Nano-Islands

Authors
de Almeida, JMMM; Vasconcelos, H; Jorge, PAS; Coelho, L;

Publication
Sensors

Abstract

2018

Optical fiber sensor Mach-Zehnder interferometer based on TiO2 coated long period fiber grating

Authors
Vasconcelos, H; De Almeida, JMMM; Jorge, PAS; Coelho, L;

Publication
Optics InfoBase Conference Papers

Abstract
The wavelength sensitivity and spectral resolution of Mach-Zehnder fiber interferometers based on uncoated and TiO2 coated LPFGs is presented and compared with TiO2 coated single LPFGs optical fiber sensors. © OSA 2018 © 2018 The Author(s)

2018

Plasmonic optical fiber sensor based on double step growth of gold nano-islands

Authors
De Almeida, JMMM; Vasconcelos, H; Jorge, PAS; Coelho, L;

Publication
Optics InfoBase Conference Papers

Abstract
Refractive index sensors based on localized surface plasmon resonance are presented through the fabrication of gold nano-islands on top of optical fiber tips. Repeated dewetting process led to an increase of sensitivity from 60 to 186nm/RIU. © OSA 2018 © 2018 The Author(s)

2017

A chemometrics approach applied to Fourier transform infrared spectroscopy (FTIR) for monitoring the spoilage of fresh salmon (Salmo salar) stored under modified atmospheres

Authors
Saraiva, C; Vasconcelos, H; de Almeida, JMMM;

Publication
INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

Abstract
The aim of this work was to investigate the potential of Fourier transform infrared spectroscopy (FTIR) to detect and predict the bacterial load of salmon fillets (Salmo salar) stored at 3, 8 and 30 degrees C under three packaging conditions: air packaging (AP) and two modified atmospheres constituted by a mixture of 50%N-2/40%CO2/10%O-2 with lemon juice (MAPL) and without lemon juice (MAP). Fresh salmon samples were periodically examined for total viable counts (TVC), specific spoilage organisms (SSO) counts, pH, FTIR and sensory assessment of freshness. Principal components analysis (PCA) allowed identification of the wavenumbers potentially correlated with the spoilage process. Linear discriminant analysis (LDA) of infrared spectral data was performed to support sensory data and to accurately identify samples freshness. The effect of the packaging atmospheres was assessed by microbial enumeration and LDA was used to determine sample packaging from the measured infrared spectra. It was verified that modified atmospheres can decrease significantly the bacterial load of fresh salmon. Lemon juice combined with MAP showed a more pronounced delay in the growth of Brochothrix thermosphacta, Photobacterium phosphoreum, psychrotrophs and H2S producers. Partial least squares regression (PLS-R) allowed estimates of TVC and psychrotrophs, lactic acid bacteria, molds and yeasts, Brochothrix thermosphacta, Enterobacteriaceae, Pseudomonas spp. and H2S producer counts from the infrared spectral data: For TVC, the root mean square error of prediction (RMSEP) value was 0.78 log cfu g(-1) for an external set of samples. According to the results, FTIR can be used as a reliable, accurate and fast method for real time freshness evaluation of salmon fillets stored under different temperatures and packaging atmospheres.