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Santos J.P.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Lozano J.,University of Extremadura
Proceedings of the 2015 10th Spanish Conference on Electron Devices, CDE 2015 | Year: 2015

A hand held wireless portable electronic nose (e-nose) has been developed for general purpose applications. It is based on non-specific micromechanized semiconductor sensors. It has been applied to the real time detection of two common aromatic defects in beer: acetaldehyde and ethyl acetate. Several measurements are made in order to check the discrimination capability of the system in the quantitative and qualitative classification these compounds in beer. Principal Component Analysis (PCA) and classification with Artificial Neural Networks are made as data processing methods. © 2015 IEEE. Source


Aparicio S.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Martinez-Ramirez S.,CSIC - Institute for the Structure of Matter | Ranz J.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Fuente J.V.,Spain Technological Institute for Construction | Hernandez M.G.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic
Materials and Design | Year: 2016

A microstructural and mechanical properties study was conducted to investigate the effect of the curing conditions on the final properties of self-compacting concrete. Two different curing conditions were considered simulating the summer conditions in coastal (20 °C and 70% relative humidity, RH) and central (cycles of 40 °C) zones in Spain. Different microstructural and mechanical parameters were measured to study the hydration using different techniques: Micro-Raman spectroscopy, nuclear magnetic resonance, compressive strength and ultrasonic testing. After 7 days of hydration the central conditions produce samples with higher hydration degree than coastal conditions, but after 28 days of curing, the hydration degree was very similar in both curing conditions. This high hydration degree after 7 days conducted to a decline or stabilization in compressive strength at long curing times. The mean chain length of the C-S-gel formed in the studied concrete was quite high comparing with other works since more Al was incorporated in the C-S-gel. It was also obtained that for high temperatures after 7 days of curing all microstructural and mechanical parameters were quite stable meaning that high temperatures accelerate the hydration of the samples. © 2016 Elsevier Ltd. Source


Santos J.P.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Fernandez M.J.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Fontecha J.L.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Matatagui D.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | And 4 more authors.
Sensors (Switzerland) | Year: 2014

A new method of depositing tin dioxide nanofibers in order to develop chemical sensors is presented. It involves an electrospinning process with in-plane electrostatic focusing over micromechanized substrates. It is a fast and reproducible method. After an annealing process, which can be performed by the substrate heaters, it is observed that the fibers are intertwined forming porous networks that are randomly distributed on the substrate. The fiber diameters oscillate from 100 nm to 200 nm and fiber lengths reach several tens of microns. Each fiber has a polycrystalline structure with multiple nano-grains. The sensors have been tested for the detection of acetone and hydrogen peroxide (precursors of the explosive triacetone triperoxide, TATP) in air in the ppm range. High and fast responses to these gases have been obtained. © 2014 by the authors; licensee MDPI, Basel, Switzerland. Source


Sayago I.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Matatagui D.,National Autonomous University of Mexico | Fernandez M.J.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Fontecha J.L.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | And 3 more authors.
Talanta | Year: 2016

A Love-wave device with graphene oxide (GO) as sensitive layer has been developed for the detection of chemical warfare agent (CWA) simulants. Sensitive films were fabricated by airbrushing GO dispersions onto Love-wave devices. The resulting Love-wave sensors detected very low CWA simulant concentrations in synthetic air at room temperature (as low as 0.2 ppm for dimethyl-methylphosphonate, DMMP, a simulant of sarin nerve gas, and 0.75 ppm for dipropylene glycol monomethyl ether, DPGME, a simulant of nitrogen mustard). High responses to DMMP and DPGME were obtained with sensitivities of 3087 and 760 Hz/ppm respectively. Very low limit of detection (LOD) values (9 and 40 ppb for DMMP and DPGME, respectively) were calculated from the achieved experimental data. The sensor exhibited outstanding sensitivity, good linearity and repeatability to all simulants tested. The detection mechanism is here explained in terms of hydrogen bonding formation between the tested CWA simulants and GO. © 2015 Elsevier B.V. All rights reserved. Source


Aleixandre M.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Santos J.P.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Sayago I.,Institute Tecnologias Fisicas Y Of La Informacion Itefi Csic | Cabellos J.M.,Instituto Madrileno Of Investigacion Y Desarrollo Rural | And 2 more authors.
Sensors (Switzerland) | Year: 2015

Two novel applications using a portable and wireless sensor system (e-nose) for the wine producing industry—The recognition and classification of musts coming from different grape ripening times and from different grape varieties—Are reported in this paper. These applications are very interesting because a lot of varieties of grapes produce musts with low and similar aromatic intensities so they are very difficult to distinguish using a sensory panel. Therefore the system could be used to monitor the ripening evolution of the different types of grapes and to assess some useful characteristics, such as the identification of the grape variety origin and to prediction of the wine quality. Ripening grade of collected samples have been also evaluated by classical analytical techniques, measuring physicochemical parameters, such as, pH, Brix, Total Acidity (TA) and Probable Grade Alcoholic (PGA). The measurements were carried out for two different harvests, using different red (Barbera, Petit Verdot, Tempranillo, and Touriga) and white (Malvar, Malvasía, Chenin Blanc, and Sauvignon Blanc) grape musts coming from the experimental cellar of the IMIDRA at Madrid. Principal Component Analysis (PCA) and Probabilistic Neural Networks (PNN) have been used to analyse the obtained data by e-nose. In addition, and the Canonical Correlation Analysis (CCA) method has been carried out to correlate the results obtained by both technologies. © 2015 by the authors; licensee MDPI, Basel, Switzerland. Source

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