Empirical Comparison of Chirp and Multitones on Experimental UWB Software Defined Radar Prototype

This paper proposes and tests an approach for an unbiased study of radar waveforms' performances. Using the ultrawide band software defined radar prototype, the performances of Chirp and Multitones are compared in range profile and detection range. The architecture was implemented and has performances comparable to the state of the art in software defined radar prototypes. The experimental results are consistent with the simulations

Empirical Comparison of Chirp and Multitones on Experimental UWB Software Defined Radar Prototype

This paper proposes and tests an approach for an unbiased study of radar waveforms' performances. Using the ultrawide band software defined radar prototype, the performances of Chirp and Multitones are compared in range profile and detection range. The architecture was implemented and has performances comparable to the state of the art in software defined radar prototypes. The experimental results are consistent with the simulations

Misidentification of PVC Microplastics in Marine Environmental Samples

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Poly(vinylchloride), PVC, is the third most demanded polymer in Europe although its presence in marine ecosystems, surprisingly, is scarcely observed. This does not reflect neither its production nor its widespread usage. Therefore, it is imperative to understand why this may happen. PVC is the least stable of the high-tonnage produced polymers as it has the highest sensitivity towards UV radiation and, therefore, photo-degradation is of maximum relevance. The big amount of additives included in PVC formulations, weathering and the different treatments required to isolate it from environmental samples can modify the surface of PVC microplastics, making their spectral identification/quantification an analytical challenge. All these factors can lead to large PVC underestimations in environmental studies, in which other polymers like PE, PP or PS outstand. Further, the fact that the infrared spectrum of weathered PVC can be confounded with that of PE is of most relevance and, therefore, remarkable misidentifications and/or wrong quantifications may occur. In this work some relevant factors that can explain the low percentages of PVC reported in the literature are discussed and special emphasis is made on the need for suitable spectroscopic databases that include PVC weathered standards. This has been confirmed by the results of a detailed study of PVC weathering under pilot-scale conditions, monitoring its spectroscopic and physical changes over time.This work is part of the project MicroplastiX (Grant PCI2020-112145) supported by the JPI_Oceans Program and by MCIN/AEI/10.13039/501100011033 and the European Union “Next Generation EU”/PRTR”; by the LAnd-Based solutions for PLAStics in the Sea (LABPLAS) Grant H2020- 101003954 and “ChemPlas” Project supported by the Agencia Estatal de Investigación (Grant PID2019-108857RB-C31/AEI/10.13039/501100011033). The Program ‘Consolidación e Estructuración de Unidades de Investigación Competitivas” of the Galician Government (Xunta de Galicia) is also acknowledged (Grant ED431C 2021/56). Funding for open access charge: Universidade da Coruña/CISUGXunta de Galicia; ED431C 2021/5

Development of an Analytical Procedure to Analyze Microplastics in Edible Macroalgae Using an Enzymatic-Oxidative Digestion

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Besides being food and a refuge to marine species, macroalgae are a powerful and renewable economic resource. However, they may introduce microplastics (MPs) in the trophic chain. We developed a reliable analytical method to characterize and quantify MPs in common and edible macroalgae. Several digestion methods and filters, along with various measurement options, were studied. A new enzymatic-oxidative protocol with a unique final filtration was selected and validated with a mixture of 5 commercial macroalgae (Undaria pinnatifida spp, Porphyra spp, Ulva spp, Laminaria ochroleuca and Himanthalia elongate). Further, it was shown that washing the macroalgae to release MPs is suboptimal and the potential adhesion of MPs to macroalgae was evaluated. A filter subsampling strategy that scans 33.64 % of its surface reduced the time required to characterize <70 μm particles and fibres directly on the 47 mm diameter filter using an IR microscope (1 sample/day).This work is a part of the projects MicroplastiX (Grant PCI2020-112145, JPI Oceans Project supported by MCIN/AEI/10.13039/501100011033 and by the European Union “Next Generation EU/PRTR”) and LAnd-Based solutions for PLAStics in the Sea, LABPLAS, (Grant H2020-101003954 supported by the EU H2020 program). The Program “Consolidación e Estructuración de Unidades de Investigación Competitivas” of the Galician Government (Xunta de Galicia) is also acknowledged (Grant ED431C 2021/56). Funding for open access charge: Universidade da Coruña/CISUGXunta de Galicia; ED431C 2021/5

New Ways for the Advanced Quality Control of Liquefied Natural Gas

[Abstract] Currently, gas chromatography is the most common analytical technique for natural gas (NG) analysis as it offers very precise results, with very low limits of detection and quantification. However, it has several drawbacks, such as low turnaround times and high cost per analysis, as well as difficulties for on-line implementation. With NG applications rising, mostly thanks to its reduced gaseous emissions in comparison with other fossil fuels, the necessity for more versatile, fast, and economic analytical methods has augmented. This work summarizes the latest advances to determine the composition and physico-chemical properties of regasified liquid natural gas, focusing on infrared spectroscopy-based techniques, as well as on data processing (chemometric techniques), necessary to obtain adequate predictions of NG properties.Part of this work was performed under the EMPIR 16ENG09 project ‘Metrological support for LNG and LBG as transport fuel (LNG III)’. This project has received funding from the EMPIR programme co-financed by the Participant States and from the European Union’s Horizon 2020 Research and Innovation programme. Mestrelab, Reganosa and Naturgy are acknowledged for hiring the services of the Group of Applied Analytical Chemistry for FTIR method development. The Program “Consolidación e Estructuración de Unidades de Investigación Competitivas” of the Galician Government (Xunta de Galicia) is also acknowledged (Grant ED431C 2021/56).Xunta de Galicia; ED431C 2021/5

Monitorization of Polyamide Microplastics Weathering Using Attenuated Total Reflectance and Microreflectance Infrared Spectrometry

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The EU goal to reduce marine plastic litter by ca. 30% by 2020 stressed the need to deploy analytical methods to ascertain the polymeric nature of a residue. Furthermore, as plastics age under natural conditions and usual databases do not include their weathered spectra, (micro)plastics in environmental samples may be unidentified. In this paper, polyamide (nylon) microplastics weathering was monitored because of its ubiquity in household commodities, clothes, fishery items and industry, whose residues end up frequently in the environment. Infrared spectra (ATR and microreflectance) and Scanning Electron Microscopy (SEM) images were collected periodically while exposing nylon to controlled weathering. It was seen that ATR was more sensitive than microreflectance to monitor the structural evolution of polyamide and that the spectra and the surface of weathered microplastics showed remarkable differences with the pristine material, which stresses the need for considering its evolution when identifying microplastics in environmental studies. The evolution of six band ratios related to the chemical evolution of this polymer are presented. SEM images revealed the formation of secondary microplastics at the most advanced weathering stages of polyamide.This work was supported through the JPI-Oceans BASEMAN and MicroplastiX projects, sponsored by the Spanish Ministry of Science and Innovation (Agencia Estatal de Investigación) -partially financed by the European Regional Development Fund program- (Grants: PCIN-2015-170-C02-01; PCIN- PCI2020-112145 and CTM2016-77945-C3-3-R, ARPA-ACUA). The Program ‘Consolidación e Estructuración de Unidades de Investigación Competitiva’ of the Galician Government (Xunta de Galicia) is also acknowledged (Grant: ED431C-2017/28)Xunta de Galicia; ED431C-2017/2

A Reliable Method for the Isolation and Characterization of Microplastics in Fish Gastrointestinal Tracts Using an Infrared Tunable Quantum Cascade Laser System

[Abstract] Societal and environmental concern due to frequent reports of microplastics in fish stomachs raised as they may accumulate along the trophic chain. The request for analysing microplastics in fish stresses two major analytical issues: sample treatment and final characterization. The, so far, workhorse for chemical characterization is infrared spectroscopy which is time-consuming. Here, a quantum cascade laser-based device is used to accelerate the characterization stage. Its novelty poses new challenges for sample processing and particle handling because the unknown particles must be transferred to a reflective slide. In this study, three sample digestion protocols (alkaline-oxidative with H2O2, and alkaline-oxidative with NaClO and enzymatic-oxidative) and three different procedures to transfer the filter cake to reflective slides are compared. A simplified enzymatic-oxidative digestion (validated through an interlaboratory exercise) combined with a Syncore® automatic evaporation system and a Laser Direct Infrared Imaging (LDIR) device is proposed first time as a reliable and relatively fast method to treat gastrointestinal tracts of fish. Analytical recoveries were studied using samples of Scomber scombrus and they were ca. 100% for big –i.e., >500 μm- and ca. 90% for medium –i.e., 200–300 μm- particles and ca. 75% for 10 μm thick fibres.This research was supported by the LAnd-Based Solutions for PLAstics in the Sea Project (LABPLAS Project), Grant Agreement No. 101003954, under the European Union's Horizon 2020 research and innovation programme, and the Integrated approach on the fate of MicroPlastics (MPs) towards healthy marine ecosystems Project (MicroplastiX project), Grant PCI2020-112145, supported by the JPI_Oceans Program and by MCIN/AEI/10.13039/501100011033 and the European Union “Next Generation EU/PRTR”. The Program ‘Consolidación e Estructuración de Unidades de Investigación Competitivas” of the Galician Government (Xunta de Galicia) is also acknowledged (Grant ED431C 2021/56)Xunta de Galicia; ED431C 2021/5

A multispectral omnidirectional stereoscopic sensor

The 3D reconstruction of an environment with a high degree of accuracy and faithful textures represents an important challenge for applications related to the multimedia and cinematography. We present in this article, the complete development, of the electronic design to the algorithmic restitution of the environment, of a multispectral omnidirectional stereoscopic sensor that tackles this problem. Although panoramic sensors exist, the vision system presented here has four channels of acquisition coupled to a projector of structured light emitting in the infra-red. This original process separates the acquisition of colors textures independently of the 3D reconstruction. The panoramic images colors are corrected starting from ICC (International Color Consorsium) profiles of the two cameras. The reconstruction of the environment uses only the invariable available on the infra-red channels. An active calibration technique is also presented. Experimental results demonstrate the feasibility of this new class of multispectral omnidirectionnal vision sensor.La reconstruction d’un environnement avec une grande précision et des textures fidèles représente un besoin important pour des applications liées aux mondes de l’événementiel, de la cinématographie et du multimédias. Nous présentons dans cet article, le développement complet, de la conception électronique à la restitution algorithmique de l’environnement, d’un système de vision stéréoscopique omnidirectionnel multi spectral permettant de répondre à ce besoin. L’architecture du système présentée ici, possède la particularité d’avoir deux caméras (munies de quatre canaux d’acquisition) couplées à un projecteur de lumière structurée infrarouge. Ce procédé original d’acquisition traite le processus d’obtention des textures couleurs indépendamment de celui de la reconstruction 3D. Les images panoramiques couleurs sont corrigées à partir des profils ICC (International Color Consorsium) des deux caméras. La reconstruction 3D de l’environnement utilise les informations disponibles sur les canaux infrarouges des deux caméras. Une étape préliminaire de calibrage actif est aussi présentée. Des résultats expérimentaux démontrent la faisabilité de cette nouvelle classe de capteur de vision multi spectrale omnidirectionnelle

Study of Temporal Variations of Equivalent Black Carbon in a Coastal City in Northwest Spain Using an Atmospheric Aerosol Data Management Software

[Abstract] Light-absorbing carbonaceous aerosols (including black carbon (BC)) pose serious health issues and play significant roles in atmospheric radiative properties. Two-year measurements (2015–2016) of aerosol light absorption, combined with measurements of sub-micrometric particles, were continuously conducted in A Coruña (northwest (NW) Spain) to determine their light absorption properties: absorption coefficients (σabs) and the absorption Ångström exponent (AAE). The mean and standard deviation of equivalent black carbon (eBC) during the period of study were 0.85 ± 0.83 µg m−3, which are lower than other values measured in urban areas of Spain and Europe. High eBC concentrations found in winter are associated with an increase in emissions from anthropogenic sources in combination with lower mixing layer heights and frequent stagnant conditions. The pronounced diurnal variability suggests a strong influence from local sources. AAE had an average value of 1.26 ± 0.22 which implies that both fossil fuel combustion and biomass burning influenced optical aerosol properties. This also highlights biomass combustion in suburban areas, where the use of wood for domestic heating is encouraged, as an important source of eBC. All data treatment was gathered using SCALA© as atmospheric aerosol data management support software program.This research was funded by the Spanish R&D Plan (PROACLIM project: CGL2014-52877-R and CRISOL project: CGL2017-85344-R) and by the Xunta de Galicia (GRC2013-047 and ED431C 2017/28).Xunta de Galicia; GRC2013-047Xunta de Galicia; ED431C 2017/2