Suchergebnisse

The reversible oxidation and reduction of Cytochrome c (Cyt c) is demonstrated with a closed bipolar electrochemical cell (CBPEC). Herein, a 4-electrode configuration was studied with the opposite poles of the bipolar electrode resting in separate aqueous and organic electrolyte solutions, respectively. Using biocompatible indium tin oxide (ITO) slides as the bipolar electrode poles, we investigated the influence of the redox potential of the reductant (decamethyferrocene or dimethylferrocene) in a trifluorotoluene organic phase on the observed voltammetry. Reversible electron transfer was only observed between Cyt c and decamethylferrocene. Use of the weaker dimethylferrocene as the reductant required a larger external bias of the driving electrodes to initiate the electron transfer reaction between the two poles of the bipolar electrode. Consequently, the surface of the ITO slide at the aqueous pole experienced a significant negative cathodic potential and underwent irreversible reduction. The biphasic setup using the 4-electrode CBPEC provides insights into electron transfer processes at an interface between two immiscible electrolyte solutions (ITIES), highlighting the strong probability of observing interfacial electron transfer between decamethylferrocene (but not dimethylferrocene) and Cyt c within the short ~ 1 V polarisable potential window available at an ITIES. ; A. G.-Q. acknowledges funding received from an Irish Research Council Government of Ireland Postdoctoral Fellowship Award (grant number GOIPD/2018/252). G. H. is grateful to the French Programme Investissement d'Avenir (PIA) "Lorraine Université d'Excellence" (Reference No. ANR-15-IDEX-04-LUE). for the partial financial support of this work. The authors are grateful to the support of the Irish Research Council and Campus France for travel support between the French and Irish groups through their joint ULYSSES programme.

AbstractBipolar electrocoagulation with aluminum sacrificial electrodes was designed to simultaneously remove Cr(VI), phosphorus, chemical oxygen demand and turbidity from both tanning, domestic and industrial wastewater. The experimental setup was demonstrated in a semi‐industrial scale for the remediation of effluents released from Fez city (Morocco), which exhibited highly variable composition and pH. The results showed that the elimination levels are enhancing with increasing of the energy consumption and electrode amount. The optimum conditions of the electrocoagulation process to reduce the pollutants in over 90% were identified at a current density of 5 mA cm–2 that takes around 10 to 30 min at neutral pH. Thus, the proposed method could be considered as an effective approach in the conventional treatment of wastewater from artisanal activities.

The use of slurries of conducting particles has been considered a way to extend the electrode area in some energy storage electrochemical cells. When suspensions of conducting particles are used in electrolytes a decreased impedance is observed, even for concentrations much lower than the theoretical percolation limits. Indeed, it is known that polarization occurs when a conducting material is immersed in an electrolyte in presence of electric fields, and bipolar electrochemistry processes may occur. This work demonstrates the dramatic drop in resistance for electrochemical cells with just a few macroscopic conducting pieces immersed in the electrolyte, in the absence of any electrical contact, through bipolar induction. Furthermore, mediation of soluble redox species between adjacent induced poles of opposite charge results in an additional mechanism for charge transfer, contributing further to the decrease in impedance. Relevant parameters like size, geometry, and spatial occupation of inducible pieces within the electric field, are relevant. Remarkably, the effects observed can explain some empirical observations previously reported for carbon suspensions and slurries. Thus, no electronic percolation requiring particle contact, nor ordering, are needed to explain the good performance associated to lowered impedance These results suggest new engineering designs for electrochemical cells with enhanced currents. ; The authors thank financing from the Ministry of Science of Spain (MAT2015-65192-R, and RTI2018-097753-B-I00, RTI2018-099826-B-I00, MAT2017-91404-EXP), and Severo Ochoa Program (SEV-2015-0496 and CEX2019-000917-S). LLA thanks the Ramon y Cajal Program contract (RYC-2013-12640). ; With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000917-S). ; Peer reviewed

[EN] Non-invasive bioelectrical recordings are usually carried out by using monopolar or bipolar disc electrodes. The poor spatial resolution is one important disadvantage of this kind of electrodes tending to pick up physiological interferences. Concentric ring electrodes have already been implemented in rigid substrates to increase the spatial resolution in the recording of bioelectrical signals such as the electrocardiography (ECG) or the electroencephalography (EEG). Our goal was to develop and test a new modular active sensor made up of a disposable sensing part with concentric ring electrodes printed on a flexible substrate by thick-film technology connected to a battery powered signal conditioning circuit, and to compare it to rigid conventional concentric ring electrodes implemented on printed circuit board. Simultaneous ECG recordings were carried out using both flexible and rigid electrodes. Results show that flexible concentric ring electrodes present lower skin-electrode contact impedance, higher amplitude and lower baseline wander than the rigid ones. ; Authors ackowledge financial support from the Spanish Government and its MICINN (MAT2009-14564-C04-02), MICINN (TEC2010-16945), the Universitat Politècnia de Valencia trough Nuevas Líneas de Investigación Multidisciplinares (PAID-05-11) for their respective research fellowship ; Prats Boluda, G.; Gil Sánchez, L.; Ye Lin, Y.; Ibáñez Civera, FJ.; Garcia Casado, FJ.; García Breijo, E. (2012). Flexible Concentric Ring Electrode for Non Invasive Bioelectrical Surface Recordings. Procedia Engineering. 47:1223-1226. https://doi.org/10.1016/j.proeng.2012.09.373 ; S ; 1223 ; 1226 ; 47

Abstract This tutorial is aimed to non-engineers using, or planning to use, surface electromyography (sEMG) as an assessment tool in the prevention, monitoring and rehabilitation fields. Its first purpose is to address the issues related to the origin and nature of the signal and to its detection (electrode size, distance, location) by one-dimensional (bipolar and linear arrays) and two-dimensional (grids) electrode systems while avoiding advanced mathematical, physical or physiological issues. Its second purpose is to outline best practices and provide general guidelines for proper signal detection. Issues related to the electrode-skin interface, signal conditioning and interpretation will be discussed in subsequent tutorials.

Leading industrial nations are investing in hydrogen technology as energy storage solution with fuel cells as the main converter to electric energy. Improvements in the performance of the key components: electrode catalyst, bipolar plates and polymer electrolyte membrane are needed to reduce costs for mass-market introduction. Consequently, surface technology has an essential role in meeting the goals. ; Funding details: Horizon 2020; Funding details: Horizon 2020 Framework Programme, H2020; Funding text 1: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 764977.

Purpose: To evaluate the impact of using monopolar thermal coagulation based on radiofrequency (RF) currents on intraoperative blood loss during liver resection. Materials and methods: A prospective randomized controlled trial was planned. Patients undergoing hepatectomy were randomized into two groups. In the Control group (n=10), hemostasis was obtained with a combination of stitches, vessel-sealing bipolar RF systems, sutures or clips. In the monopolar radiofrequency coagulation (MRFC) group (n=18), hemostasis was mainly obtained using an internally cooled monopolar RF electrode. Results: No differences in demographic or clinical characteristics were found between groups. Mean blood loss during liver resection in the Control group was more than twice that of the MRFC group (556±471 ml vs. 225±313 ml, p=0.02). The adjusted mean bleeding/transection area was also significantly higher in the Control group (7.0±3.3 ml/cm2 vs. 2.8±4.0 ml/cm2 , p=0.006). No significant differences were observed in the rate of complications between the groups. Conclusions: The findings suggest that the monopolar electrocoagulation created with an internally-cooled RF electrode considerably reduces intraoperative blood loss during liver resection. ; This work was supported by a medical research grant from the Spanish Government (FIS PI080934) and by Spanish "Programa Estatal de Investigacion, Desarrollo e Innovacion Orientada a los Retos de la Sociedad" under Grant TEC2014-52383-C3-R (TEC2014-52383-C3-1-R and TEC2014-52383-C3-3-R). ; Quesada-Diez, R.; Poves, I.; Berjano, E.; Vilaplana, C.; Andaluz, A.; Moll, X.; Dorcaratto, D. (2017). Impact of monopolar radiofrequency coagulation on intraoperative blood loss during liver resection: a prospective randomised controlled trial. International Journal of Hyperthermia. 33(2):135-141. https://doi.org/10.1080/02656736.2016.1231938 ; S ; 135 ; 141 ; 33 ; 2

[EN] Radiofrequency (RF) cardiac ablation is used to treat certain types of arrhythmias. In the epicardial approach, efficacy of RF ablation is uncertain due to the presence of epicardial adipose tissue interposed between the ablation electrode and the atrial wall. We planned a feasibility study based on a theoretical model in order to assess a new technique to estimate the quantity of fat by conducting bioimpedance measurements using a multi-electrode probe. The finite element method was used to solve the electrical problem. The results showed that the measured impedance profile coincided approximately with the epicardial fat profile measured under the probe electrodes and also that the thicker the epicardial fat, the higher the impedance values. When the lateral fat width was less than 4.5 mm, the impedance values altered, suggesting that measurements should always be conducted over a sizeable fat layer. We concluded that impedance measurement could be a practical method of assessing epicardial fat prior to RF intraoperative cardiac ablation, i.e. 'to map' the amount of adipose tissue under the probe. ; This work was supported by a research grant from the Spanish Government in the 'Plan Nacional de I+D+I del Ministerio de Ciencia e Innovacion' (TEC2008-01369/TEC). The English revision and correction of this note was funded by the Universidad Politecnica de Valencia, Spain. ; González-Suárez, A.; Hornero, F.; Berjano, E. (2010). Impedance measurement to assess epicardial fat prior to RF intraoperative cardiac ablation: a feasibility study using a computer model. Physiological Measurement. 31(11):95-104. https://doi.org/10.1088/0967-3334/31/11/N03 ; S ; 95 ; 104 ; 31 ; 11 ; Ba, M., Fornés, P., Nutu, O., Latrémouille, C., Carpentier, A., & Chachques, J. C. (2008). Treatment of atrial fibrillation by surgical epicardial ablation: Bipolar radiofrequency versus cryoablation. Archives of Cardiovascular Diseases, 101(11-12), 763-768. doi:10.1016/j.acvd.2008.07.004 ; Benjamin, E. J. (1994). Independent risk factors ...

AbstractHydrogen, as a clean energy carrier, is of great potential to be an alternative fuel in the future. Proton exchange membrane (PEM) water electrolysis is hailed as the most desired technology for high purity hydrogen production and self-consistent with volatility of renewable energies, has ignited much attention in the past decades based on the high current density, greater energy efficiency, small mass-volume characteristic, easy handling and maintenance. To date, substantial efforts have been devoted to the development of advanced electrocatalysts to improve electrolytic efficiency and reduce the cost of PEM electrolyser. In this review, we firstly compare the alkaline water electrolysis (AWE), solid oxide electrolysis (SOE), and PEM water electrolysis and highlight the advantages of PEM water electrolysis. Furthermore, we summarize the recent progress in PEM water electrolysis including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts in the acidic electrolyte. We also introduce other PEM cell components (including membrane electrode assembly, current collector, and bipolar plate). Finally, the current challenges and an outlook for the future development of PEM water electrolysis technology for application in future hydrogen production are provided.

This letter presents dual functions including selector and memory switching in a V/SiOx/AlOy/p++Si resistive memory device by simply controlling compliance current limit (CCL). Unidirectional threshold switching is observed after a positive forming with low CCL of 1 μA. The shifts to the V-electrode side of the oxygen form the VOx layer, where the threshold switching can be explained by the metal-insulation-transition phenomenon. For higher CCL (30 μA) applied to the device, a bipolar memory switching is obtained, which is attributed to formation and rupture of the conducting filament in SiOy layer. 1.5-nm-thick AlOy layer with high thermal conductivity plays an important role in lowering the off-current for memory and threshold switching. Through the temperature dependence, high-energy barrier (0.463 eV) in the LRS is confirmed, which can cause nonlinearity in a low-resistance state. The smaller the CCL, the higher the nonlinearity, which provides a larger array size in the cross-point array. The coexistence of memory and threshold switching in accordance with the CCL provides the flexibility to control the device for its intended use. ; This work was supported by a grant from the National Research Foundation of Korea (NRF), funded by the Korean government (MSIP) (2018R1A2A1A05023517).