Experimental Quantification of the Effect of Nonlinearities on the EIS Spectra of the Cathodic Electrode of an Alkaline Electrolyzer

[EN] Electrochemical impedance spectroscopy (EIS) is a very powerful tool to study the behavior of electrochemical systems. According to Ohm¿s generalized law, the impedance concept is only valid if the linearity condition is met. In the case that the linearity condition is not achieved, the obtained impedance spectra will present distortions which may lead to biased or even erroneous results and conclusions. In this work, an experimental quantification of the effect of nonlinearities on EIS spectra was performed in order to determine the order of magnitude of the effect of the nonlinearity of the system on the obtained spectra of the cathodic electrode of an alkaline electrolyzer.The authors are very grateful to the Generalitat Valenciana for its economic support in form of Vali+d grant (Ref: ACIF-2013-268).Giner-Sanz, J.; Ortega, E.; Pérez-Herranz, V. (2017). Experimental Quantification of the Effect of Nonlinearities on the EIS Spectra of the Cathodic Electrode of an Alkaline Electrolyzer. Fuel Cells. 17(3):391-401. https://doi.org/10.1002/fuce.201600137S39140117

Optimization of the electrochemical impedance spectroscopy measurement parameters for PEM fuel cell spectrum determination

Currently, electrochemical Impedance Spectroscopy (EIS) is a widely used tool for the study of electrochemical systems, in general; and fuel cells, in particular. A great effort is typically invested in the analysis of the obtained spectra; whereas, little time is usually spent optimizing the measurement parameters used to obtain these spectra. In general, the default settings provided by the control software used to perform the measurements, or the parameters used in similar systems available in literature, are selected to carry out the measurements. The goal of this work is to determine the optimal measurement parameters for obtaining impedance spectra of a commercial PEM fuel cell. In order to achieve this, a 2^5 factorial design was considered. Five factors were considered, the five impedance spectroscopy measurement parameters: maximum integration time; minimum number of integration cycles; number of stabilization cycles; maximum stabilization time; and minimum cycle fraction. For each factor combination envisaged in the experimental design, the cell spectrum was obtained in given operation conditions, for which the reference spectrum of the system was known, since it had been determined in previous works. The experimentally obtained spectra were fitted to the reference electric equivalent circuit. The mean square error between the experimental data fitting and the reference spectrum fitting was determined in each case, and was used as the dependant variable for the experimental design analysis. An analysis of the variance was performed in order to determine which measurement parameters have a significant effect on the dependant variable; and a model relating the dependant variable and the measurement parameters was built. This model was used in order to obtain the optimal value of each one of the measurement parameters that minimized the mean square error of the fit obtained from the experimental data with respect to the reference fit.The authors are very grateful to the Generalitat Valenciana for its economic support in form of Vali+d grant (Ref: ACIF-2013-268).Giner Sanz, JJ.; Ortega Navarro, EM.; Pérez-Herranz, V. (2015). Optimization of the electrochemical impedance spectroscopy measurement parameters for PEM fuel cell spectrum determination. Electrochimica Acta. 174:1290-1298. https://doi.org/10.1016/j.electacta.2015.06.106S1290129817

Compilation of parameterized seismogenic sources in Iberia for the SHARE European-scale seismic source model.

Abstract: SHARE (Seismic Hazard Harmonization in Europe) is an EC-funded project (FP7) that aims to evaluate European seismic hazards using an integrated, standardized approach. In the context of SHARE, we are compiling a fully-parameterized active fault database for Iberia and the nearby offshore region. The principal goal of this initiative is for fault sources in the Iberian region to be represented in SHARE and incorporated into the source model that will be used to produce seismic hazard maps at the European scale. The SHARE project relies heavily on input from many regional experts throughout the Euro-Mediterranean region. At the SHARE regional meeting for Iberia, the 2010 Working Group on Iberian Seismogenic Sources (WGISS) was established; these researchers are contributing to this large effort by providing their data to the Iberian regional integrators in a standardized format. The development of the SHARE Iberian active fault database is occurring in parallel with IBERFAULT, another ongoing effort to compile a database of active faults in the Iberian region. The SHARE Iberian active fault database synthesizes a wide range of geological and geophysical observations on active seismogenic sources, and incorporates existing compilations (e.g., Cabral, 1995; Silva et al., 2008), original data contributed directly from researchers, data compiled from the literature, parameters estimated using empirical and analytical relationships, and, where necessary, parameters derived using expert judgment. The Iberian seismogenic source model derived for SHARE will be the first regional-scale source model for Iberia that includes fault data and follows an internationally standardized approach (Basili et al., 2008; 2009). This model can be used in both seismic hazard and risk analyses and will be appropriate for use in Iberian- and European-scale assessments

Total harmonic distortion based method for linearity assessment in electrochemical systems in the context of EIS

Electrochemical Impedance Spectroscopy (EIS) is a widely used electrochemical measurement technique that has been used in a great spectrum of fields since it allows deconvolving the individual physic- chemical processes that take place in a given system. Ohm s generalized law, and thus the impedance concept, are only valid if 4 conditions are fulfilled: causality, finiteness, stationarity and linearity. In the case that any of these conditions is not achieved, the obtained impedance spectra will present distortions that may lead to biased or even erroneous results and conclusions. For this reason it is crucial to verify if the 4 conditions are fulfilled, before accepting the results extracted from impedance spectra. In this work, a linearity assessment quantitative method based in the total harmonic distortion (THD) parameter is presented and verified experimentally. The experimental validation of the implemented method showed that the implemented method is able to assess quantitatively the linearity of the system. In addition, it is also able to determine the threshold frequency above which the system will not present significant nonlinear effects even for large perturbation amplitudes. It was observed that the THD method is more sensitive to nonlinear effects than the spectra themselves.The authors are very grateful to the Generalitat Valenciana for its economic support in form of Vali+d grant (Ref: ACIF-2013-268).Giner Sanz, JJ.; Ortega Navarro, EM.; Pérez-Herranz, V. (2015). Total harmonic distortion based method for linearity assessment in electrochemical systems in the context of EIS. Electrochimica Acta. 186:598-612. https://doi.org/10.1016/j.electacta.2015.10.152S59861218

Montecarlo based quantitative Kramers-Kronig test for PEMFC impedance spectrum validation

Electrochemical Impedance Spectroscopy (EIS) is a very powerful tool to study the behaviour of electrochemical systems. At present, it is widely used in the fuel cell field in order to study challenging cutting edge issues as membrane drying or gas diffusion layer flooding amongst others. The proper analysis of impedance data requires the fulfilment of four fundamental conditions: causality, linearity, stability and finiteness. The non compliance with any of these conditions may lead to biased, or even misguided, conclusions. Therefore it is critical to verify the compliance of these conditions before accepting any analysis performed on an experimental spectrum. This is even more important in a fuel cell experimental spectrum analysis, since fuel cells are markedly non stationary systems. The aim of this work is to establish an impedance spectrum quantitative validation technique to validate the whole experimental spectrum and to identify the individual points within a spectrum that do not comply any of the four conditions, in order to remove these inconsistent points from the analysis. The designed validation method consists in a Kramers Kronig (KK) validation test, by equivalent electrical circuit fitting, coupled with a Montecarlo error propagation method. In a first step, the experimental spectrum is fitted to a particular electrical equivalent circuit, which satisfies the KK relations. Then, in a second step, a statistical Montecarlo method is used in order to propagate the model fitting parameter uncertainty through the model. Using this approach, a consistency region is built for a given confidence level: the experimental points inside this region are considered consistent for the given confidence level, whereas the outside points are rejected. The method was used on PEMFC experimental impedance spectra; and it successfully managed to identify inconsistent points, associated to no stationarities.The authors are very grateful to the Generalitat Valenciana for its economic support in form of Vali+d grant (Ref: ACIF-2013-268).Giner Sanz, JJ.; Ortega Navarro, EM.; Pérez-Herranz, V. (2015). Montecarlo based quantitative Kramers-Kronig test for PEMFC impedance spectrum validation. International Journal of Hydrogen Energy. 40(34):11279-11293. https://doi.org/10.1016/j.ijhydene.2015.03.135S1127911293403

Analysis of norfloxacin ecotoxicity and the relation with its degradation by means of electrochemical oxidation using different anodes

[EN] In this work, ecotoxicological bioassays based on Lactuca sativa seeds and bioluminescent bacterium (Vibrio fischeri) have been carried out in order to quantify the toxicity of Norfloxacin (NOR) and sodium sulfate solutions, before and after treating them using electrochemical advanced oxidation. The effect of some process variables (anode material, reactor configuration and applied current) on the toxicity evolution of the treated solution has been studied. A NOR solution shows an EC50 (5 days) of 336 mg L-1 towards Lactuca sativa. This threshold NOR concentration decreases with sodium sulfate concentration, in solutions that contain simultaneously Norfloxacin and sodium sulfate. In every case considered in this work, the electrochemical advanced oxidation process increased the toxicity (towards both Lactuca sativa and Vibrio fischeri) of the solution. This toxicity increase is mainly due to the persulfate formation during the electrochemical treatment. From a final solution toxicity point of view, the best results were obtained using a BDD anode in a divided reactor applying the lowest current intensity.The authors are very grateful to the Ministerio de Economia y Competitividad (Projects CTQ2015-65202-C2-1-R and RTI2018-101341-B-C21) for their economic support.Montañés, M.; García Gabaldón, M.; Roca-Pérez, L.; Giner-Sanz, JJ.; Mora-Gómez, J.; Pérez-Herranz, V. (2020). Analysis of norfloxacin ecotoxicity and the relation with its degradation by means of electrochemical oxidation using different anodes. Ecotoxicology and Environmental Safety. 188:1-10. https://doi.org/10.1016/j.ecoenv.2019.109923S110188Banks, M. K., & Schultz, K. E. (2005). Comparison of Plants for Germination Toxicity Tests in Petroleum-Contaminated Soils. Water, Air, and Soil Pollution, 167(1-4), 211-219. doi:10.1007/s11270-005-8553-4Barreto, J. P. d. P., Araujo, K. C. d. F., de Araujo, D. M., & Martinez-Huitle, C. A. (2015). Effect of sp3/sp2 Ratio on Boron Doped Diamond Films for Producing Persulfate. ECS Electrochemistry Letters, 4(12), E9-E11. doi:10.1149/2.0061512eelBueno, F., Borba, F. H., Pellenz, L., Schmitz, M., Godoi, B., Espinoza-Quiñones, F. R., … Módenes, A. N. (2018). Degradation of ciprofloxacin by the Electrochemical Peroxidation process using stainless steel electrodes. Journal of Environmental Chemical Engineering, 6(2), 2855-2864. doi:10.1016/j.jece.2018.04.033Carlesi Jara, C., Fino, D., Specchia, V., Saracco, G., & Spinelli, P. (2007). Electrochemical removal of antibiotics from wastewaters. Applied Catalysis B: Environmental, 70(1-4), 479-487. doi:10.1016/j.apcatb.2005.11.035Charles, J., Crini, G., Degiorgi, F., Sancey, B., Morin-Crini, N., & Badot, P.-M. (2013). Unexpected toxic interactions in the freshwater amphipod Gammarus pulex (L.) exposed to binary copper and nickel mixtures. Environmental Science and Pollution Research, 21(2), 1099-1111. doi:10.1007/s11356-013-1978-1Chen, M., & Chu, W. (2012). Degradation of antibiotic norfloxacin in aqueous solution by visible-light-mediated C-TiO2 photocatalysis. Journal of Hazardous Materials, 219-220, 183-189. doi:10.1016/j.jhazmat.2012.03.074Coledam, D. A. C., Aquino, J. M., Silva, B. F., Silva, A. J., & Rocha-Filho, R. C. (2016). Electrochemical mineralization of norfloxacin using distinct boron-doped diamond anodes in a filter-press reactor, with investigations of toxicity and oxidation by-products. Electrochimica Acta, 213, 856-864. doi:10.1016/j.electacta.2016.08.003Da Silva, S. W., Navarro, E. M. O., Rodrigues, M. A. S., Bernardes, A. M., & Pérez-Herranz, V. (2019). Using p-Si/BDD anode for the electrochemical oxidation of norfloxacin. Journal of Electroanalytical Chemistry, 832, 112-120. doi:10.1016/j.jelechem.2018.10.049Davis, J., Baygents, J. C., & Farrell, J. (2014). Understanding Persulfate Production at Boron Doped Diamond Film Anodes. Electrochimica Acta, 150, 68-74. doi:10.1016/j.electacta.2014.10.104Oliveira, G. A. R. de, Leme, D. M., de Lapuente, J., Brito, L. B., Porredón, C., Rodrigues, L. de B., … Oliveira, D. P. de. (2018). A test battery for assessing the ecotoxic effects of textile dyes. Chemico-Biological Interactions, 291, 171-179. doi:10.1016/j.cbi.2018.06.026Drèze, V., Monod, G., Cravedi, J.-P., Biagianti-Risbourg, S., & Le Gac, F. (2000). Ecotoxicology, 9(1/2), 93-103. doi:10.1023/a:1008976431227Flaherty, C. M., & Dodson, S. I. (2005). Effects of pharmaceuticals on Daphnia survival, growth, and reproduction. Chemosphere, 61(2), 200-207. doi:10.1016/j.chemosphere.2005.02.016González-Pleiter, M., Gonzalo, S., Rodea-Palomares, I., Leganés, F., Rosal, R., Boltes, K., … Fernández-Piñas, F. (2013). Toxicity of five antibiotics and their mixtures towards photosynthetic aquatic organisms: Implications for environmental risk assessment. Water Research, 47(6), 2050-2064. doi:10.1016/j.watres.2013.01.020Gustavson, K. E., Sonsthagen, S. A., Crunkilton, R. A., & Harkin, J. M. (2000). Groundwater toxicity assessment using bioassay, chemical, and toxicity identification evaluation analyses. Environmental Toxicology, 15(5), 421-430. doi:10.1002/1522-7278(2000)15:53.0.co;2-zHeberle, A. N. A., Alves, M. E. P., da Silva, S. W., Klauck, C. R., Rodrigues, M. A. S., & Bernardes, A. M. (2019). Phytotoxicity and genotoxicity evaluation of 2,4,6-tribromophenol solution treated by UV-based oxidation processes. Environmental Pollution, 249, 354-361. doi:10.1016/j.envpol.2019.03.057Iniesta, J. (2001). Electrochemical oxidation of phenol at boron-doped diamond electrode. Electrochimica Acta, 46(23), 3573-3578. doi:10.1016/s0013-4686(01)00630-2Larsson, D. G. J., de Pedro, C., & Paxeus, N. (2007). Effluent from drug manufactures contains extremely high levels of pharmaceuticals. 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Toxics, 6(1), 8. doi:10.3390/toxics6010008Mora-Gómez, J., García-Gabaldón, M., Ortega, E., Sánchez-Rivera, M.-J., Mestre, S., & Pérez-Herranz, V. (2018). Evaluation of new ceramic electrodes based on Sb-doped SnO2 for the removal of emerging compounds present in wastewater. Ceramics International, 44(2), 2216-2222. doi:10.1016/j.ceramint.2017.10.178Mora-Gomez, J., Ortega, E., Mestre, S., Pérez-Herranz, V., & García-Gabaldón, M. (2019). Electrochemical degradation of norfloxacin using BDD and new Sb-doped SnO2 ceramic anodes in an electrochemical reactor in the presence and absence of a cation-exchange membrane. Separation and Purification Technology, 208, 68-75. doi:10.1016/j.seppur.2018.05.017Özcan, A., Atılır Özcan, A., & Demirci, Y. (2016). Evaluation of mineralization kinetics and pathway of norfloxacin removal from water by electro-Fenton treatment. Chemical Engineering Journal, 304, 518-526. doi:10.1016/j.cej.2016.06.105Priac, A., Badot, P.-M., & Crini, G. (2017). Treated wastewater phytotoxicity assessment using Lactuca sativa : Focus on germination and root elongation test parameters. Comptes Rendus Biologies, 340(3), 188-194. doi:10.1016/j.crvi.2017.01.002Radix, P., Léonard, M., Papantoniou, C., Roman, G., Saouter, E., Gallotti-Schmitt, S., … Vasseur, P. (2000). Comparison of Four Chronic Toxicity Tests Using Algae, Bacteria, and Invertebrates Assessed with Sixteen Chemicals. Ecotoxicology and Environmental Safety, 47(2), 186-194. doi:10.1006/eesa.2000.1966Rizzo, L. (2011). Bioassays as a tool for evaluating advanced oxidation processes in water and wastewater treatment. Water Research, 45(15), 4311-4340. doi:10.1016/j.watres.2011.05.035Seco, J. I., Fernández-Pereira, C., & Vale, J. (2003). A study of the leachate toxicity of metal-containing solid wastes using Daphnia magna. Ecotoxicology and Environmental Safety, 56(3), 339-350. doi:10.1016/s0147-6513(03)00102-7Uzu, G., Sobanska, S., Sarret, G., Muñoz, M., & Dumat, C. (2010). Foliar Lead Uptake by Lettuce Exposed to Atmospheric Fallouts. Environmental Science & Technology, 44(3), 1036-1042. doi:10.1021/es902190uVasconcelos, T. G., Henriques, D. M., König, A., Martins, A. F., & Kümmerer, K. (2009). Photo-degradation of the antimicrobial ciprofloxacin at high pH: Identification and biodegradability assessment of the primary by-products. Chemosphere, 76(4), 487-493. doi:10.1016/j.chemosphere.2009.03.022Wang, W. C., & Freemark, K. (1995). The Use of Plants for Environmental Monitoring and Assessment. Ecotoxicology and Environmental Safety, 30(3), 289-301. doi:10.1006/eesa.1995.1033Wang, X., Sun, C., Gao, S., Wang, L., & Shuokui, H. (2001). Validation of germination rate and root elongation as indicator to assess phytotoxicity with Cucumis sativus. Chemosphere, 44(8), 1711-1721. doi:10.1016/s0045-6535(00)00520-8Yang, L.-H., Ying, G.-G., Su, H.-C., Stauber, J. L., Adams, M. S., & Binet, M. T. (2008). 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Prediction of long-term outcomes of HIV-infected patients developing non-AIDS events using a multistate approach

Outcomes of people living with HIV (PLWH) developing non-AIDS events (NAEs) remain poorly defined. We aimed to classify NAEs according to severity, and to describe clinical outcomes and prognostic factors after NAE occurrence using data from CoRIS, a large Spanish HIV cohort from 2004 to 2013. Prospective multicenter cohort study. Using a multistate approach we estimated 3 transition probabilities: from alive and NAE-free to alive and NAE-experienced ("NAE development"); from alive and NAE-experienced to death ("Death after NAE"); and from alive and NAE-free to death ("Death without NAE"). We analyzed the effect of different covariates, including demographic, immunologic and virologic data, on death or NAE development, based on estimates of hazard ratios (HR). We focused on the transition "Death after NAE". 8,789 PLWH were followed-up until death, cohort censoring or loss to follow-up. 792 first incident NAEs occurred in 9.01% PLWH (incidence rate 28.76; 95% confidence interval [CI], 26.80-30.84, per 1000 patient-years). 112 (14.14%) NAE-experienced PLWH and 240 (2.73%) NAE-free PLWH died. Adjusted HR for the transition "Death after NAE" was 12.1 (95%CI, 4.90-29.89). There was a graded increase in the adjusted HRs for mortality according to NAE severity category: HR (95%CI), 4.02 (2.45-6.57) for intermediate-severity; and 9.85 (5.45-17.81) for serious NAEs compared to low-severity NAEs. Male sex (HR 2.04; 95% CI, 1.11-3.84), ag