Advances in copper electrodeposition in chloride excess. A theoretical and experimental approach.

This is an in depth study in the knowledge of the nucleation and growth mechanism that governs copper electrodeposition in excess chloride media. In these conditions copper electro-reduction takes place via two well-separated steps, since the Cu(I) intermediate is stabilized through chloride complexation. The process was studied in two media, a deep eutectic solvent (DES) based on a mixture of urea and choline chloride, and in excess chloride aqueous solution, in order to also analyse solvent influence on the early stages of the deposition process. In both media, copper electrodeposition follows a nucleation and a diffusion controlled three-dimensional growth mechanism. In line with a previous work a double potentiostatic step signal was employed to record j-t transients associated to both nucleation and growth stages, and from them, the whole mechanistic analysis of the copper electrodeposition was performed. This analysis involved the calculation of the surface concentrations of Cu(II), free Cu(I) and complexed Cu(I) for any time and potential required and the application of Sharifker-Hills model, jm2tm products and rising part analysis including the calculated parameters, which are strengthened as valuable tools for complete copper electrodeposition analysis in these media

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Estudio de procesos de transferencia iónica a través de membranas líquidas mediante técnicas voltamétricas y croniopotenciométricas

Esta Tesis se centra principalmente en la aplicación de metodologías electroquímicas tradicionales y novedosas al estudio de procesos de transferencia iónica simple y facilitada en ITIES (Interfase entre Dos Disoluciones Electrolíticas Inmiscibles) en sistemas de una y dos interfases líquido/líquido polarizables. El estudio y caracterización teórica de la respuesta electroquímica de este tipo de sistemas es de gran interés para determinar parámetros termodinámicos, cinéticos y de transporte asociados a la transferencia iónica, que pueden relacionarse con propiedades fisicoquímicas de los iones estudiados y, adicionalmente, permitir ganar conocimiento acerca de los mecanismos implicados en la transferencia de iones a través de membranas biológicas y en procesos de conversión y almacenamiento de energía. Los tratamientos teóricos que se desarrollan en la presente Tesis conducen a la obtención de ecuaciones simples, explícitas y generales para la aplicación de distintas técnicas voltamétricas, como Voltametría de Doble Pulso Diferencial, Voltametría de Onda Cuadrada y Voltametría Cíclica, y cronopotenciométricas, como Cronopotenciometría Derivativa Recíproca y Cronopotenciometría Derivativa Recíproca Cíclica, entre otras, al estudio de la transferencia simple y facilitada en sistemas de membrana líquida de una y dos interfases polarizables. Las repuestas de las distintas técnicas se estudian y caracterizan en profundidad, y se proponen estrategias y métodos para la obtención de potenciales estándar de transferencia, coeficientes de difusión en las fases acuosa y orgánica, constantes de complejación con ionóforos, y constantes cinéticas asociadas a la transferencia iónica y a la reacción de complejación en el caso de la transferencia iónica facilitada. Todos los resultados teóricos se verifican experimentalmente utilizando sensores amperométricos de membrana polimérica plastificada mediante el análisis de la transferencia iónica de una serie de especies de gran interés en la actualidad, como iones de líquidos iónicos, fármacos catiónicos anfifílicos, iones de clorocomplejos metálicos o aminas orgánicas protonadas. Como resultado se obtienen conclusiones y se establecen patrones acerca de la relación estructura/lipofilia o estructura/toxicidad de dichas especies, y además, se caracteriza teórica y experimentalmente la trasferencia conjunta de los dos iones constituyentes de una sal soluble en agua. The present Doctoral Dissertation is mainly focused on the application of traditional and novel electrochemical techniques to the study of simple and facilitated ion transfer processes at ITIES (Interface between Two Immiscible Electrolyte Solutions) at liquid membrane systems of one and two polarized interfaces. The study and theoretical characterization of the electrochemical responses of these kind of systems is of great interest to implement and develop methods and strategies to determine thermodynamic, kinetic and mass transport parameters associated to the ion transfer, which can be related with important physicochemical properties of the species assayed and, additionally, allow gaining insights into the mechanisms involved in ion transfer at biomembranes and in energy conversion and energy storage processes. The theoretical treatments developed in the present Thesis lead to the obtaining of simple, explicit and analytical equations for the application of different voltammetric techniques, such as Differential Double Pulse Voltammetry, Square Wave Voltammetry and Cyclic Voltammetry, and chronopotentiometric techniques, such as Reciprocal Derivative Chronopotentiometry and Cyclic Reciprocal Derivative Chronopotentiometry, among others, to the study of the simple and the facilitated ion transfer at liquid membrane systems of one and two polarized interfaces. The responses of the different techniques are studied and characterized in-depth, and strategies and methods are proposed for the obtaining of standard ion transfer potential values, diffusion coefficients in the organic and the aqueous phases, complexation constants with ionophores, and kinetic constants associated to the ion transfer and to the complexation reaction in the case of the facilitated ion transfer. All the theoretical results are verified experimentally by using solvent polymeric amperometric ion sensors through the analysis of the ion transfer of a series of species currently very interesting, such as ionic liquids, catamphiphilic drugs, metal chloro complex ions and protonated organic amines. As a result, conclusions and patterns about the relation structure/lipophilicity and structure/toxicity of these species are established, and besides, the theoretical and experimental characterization of the joint transfer of the two ions constituting a water-soluble salt is carried out

Synthesis and Applications of Bimetallic-Derived Catalysts on Semiconductor Materials for Photoelectrocatalytic Processes

Photoelectrocatalysis takes advantage of electrocatalytic and photocatalytic processes [...

Insights into the Voltammetry of Cavity Microelectrodes Filled with Metal Powders: The Value of Square Wave Voltammetry

International audienceCavity MicroElectrodes (CMEs) offer a valuable platform to evaluate the electrocatalytic performance of micro-and nano-particulate materials. The technical factors and physicochemical processes affecting the electrochemical response at CMEs are to be recognized, specifically, the accessibility of redox species to the electrocatalyst surface. With this aim, the voltammetric response of CMEs is investigated through a joint experimental and theoretical approach including a comparative study of cyclic and square wave voltammetry (SWV). Experiments reveal a capacitive distortion of the response that increases with the powder surface area, but with a faradaic response analogous to that of recessed or inlaid microdisks, i.e. with electrochemical reactions occurring essentially on the first layer of the powder load. We show that SWV is well suited to discriminate Faradaic processes at CMEs and we present accurate mathematical expressions to describe it. These results provide guidelines for the design and analysis of CME voltammetric measurements

Advances in copper electrodeposition in chloride excess. A theoretical and experimental approach.

This is an in depth study in the knowledge of the nucleation and growth mechanism that governs copper electrodeposition in excess chloride media. In these conditions copper electro-reduction takes place via two well-separated steps, since the Cu(I) intermediate is stabilized through chloride complexation. The process was studied in two media, a deep eutectic solvent (DES) based on a mixture of urea and choline chloride, and in excess chloride aqueous solution, in order to also analyse solvent influence on the early stages of the deposition process. In both media, copper electrodeposition follows a nucleation and a diffusion controlled three-dimensional growth mechanism. In line with a previous work a double potentiostatic step signal was employed to record j-t transients associated to both nucleation and growth stages, and from them, the whole mechanistic analysis of the copper electrodeposition was performed. This analysis involved the calculation of the surface concentrations of Cu(II), free Cu(I) and complexed Cu(I) for any time and potential required and the application of Sharifker-Hills model, jm2tm products and rising part analysis including the calculated parameters, which are strengthened as valuable tools for complete copper electrodeposition analysis in these media

Photoelectrocatalytic conversion of urea under solar illumination using Ni decorated Ti-Fe2O3 electrodes

International audienceTo reduce the energy cost and environmental impact of biological nitrogen removal in wastewater treatment plants, it would be advantageous to treat urea contained in urine at the source. In this perspective, FTO/Ti-Fe2O3 (nanorods) photoelectrodes decorated with Ni as catalyst are developed and tested for urea photoelectrocatalytic oxidation under solar illumination. Gains up to 0.50 V in oxidation onset potential vs. metallic Ni are obtained thanks to a Ni photoelectrodeposition method. In situ transmission measurements (based on NiOOH light absorption) during electrochemical cycling allowed to evaluate the state of active Ni sites and confirmed that urea oxidation mechanism is of EC type. Photoelectrolyses give faradaic efficiencies of 10–18% and 9-35% for N2 and O2 formation, respectively. A significant and unexpected NO2− production (∼65%) is detected indicating another or incomplete reaction pathway. The photoelectrocatalytic removal of nitrogen from urea solutions is demonstrated but requires catalysts with higher selectivity towards N2

3D patterning of silicon by contact etching with anodically biased nanoporous gold electrodes

A novel strategy to achieve 3D pattern transfer into silicon in a single step without using lithography is presented. Etching is performed electrochemically in HF media by contacting silicon with a positively biased, patterned, metal electrode. Dissolution is localized at the Si/metal contacts and patterning is obtained as the electrode digs into the substrate. Previous attempts at imprinting Si using bulk metal electrodes have been limited by electrolyte blockage. Here, the problem is solved by using, for the first time, a nanoporous metal electrode that allows the electrolyte to access the entire Si/metal interface, irrespective of the electrode dimensions. As a proof of concept, imprinting of well-defined arrays of inverted pyramids has been performed with sub-micrometer spatial resolution over 1 mm2 using a nanoporous gold electrode of the complementary shape. Under a polarization of +0.3 V/SME in 5 M HF, the etch rate is ~0.5 μm min−1. The pyramidal pattern is imprinted independently of the Si crystallographic orientation. This maskless imprinting technique opens new opportunities in the fabrication of Si microstructures. Keywords: Silicon, Nanoporous gold, Imprinting, Microstructure, MAC

Pseudomonas aeruginosa antibiotic susceptibility profiles, genomic epidemiology and resistance mechanisms: a nation-wide five-year time lapse analysisResearch in context

Summary: Background: Pseudomonas aeruginosa healthcare-associated infections are one of the top antimicrobial resistance threats world-wide. In order to analyze the current trends, we performed a Spanish nation-wide high-resolution analysis of the susceptibility profiles, the genomic epidemiology and the resistome of P. aeruginosa over a five-year time lapse. Methods: A total of 3.180 nonduplicated P. aeruginosa clinical isolates from two Spanish nation-wide surveys performed in October 2017 and 2022 were analyzed. MICs of 13 antipseudomonals were determined by ISO-EUCAST. Multidrug resistance (MDR)/extensively drug resistance (XDR)/difficult to treat resistance (DTR)/pandrug resistance (PDR) profiles were defined following established criteria. All XDR/DTR isolates were subjected to whole genome sequencing (WGS). Findings: A decrease in resistance to all tested antibiotics, including older and newer antimicrobials, was observed in 2022 vs 2017. Likewise, a major reduction of XDR (15.2% vs 5.9%) and DTR (4.2 vs 2.1%) profiles was evidenced, and even more patent among ICU isolates [XDR (26.0% vs 6.0%) and DTR (8.9% vs 2.6%)] (p < 0.001). The prevalence of Extended-spectrum β-lactamase/carbapenemase production was slightly lower in 2022 (2.1%. vs 3.1%, p = 0.064). However, there was a significant increase in the proportion of carbapenemase production among carbapenem-resistant strains (29.4% vs 18.1%, p = 0.0246). While ST175 was still the most frequent clone among XDR, a slight reduction in its prevalence was noted (35.9% vs 45.5%, p = 0.106) as opposed to ST235 which increased significantly (24.3% vs 12.3%, p = 0.0062). Interpretation: While the generalized decrease in P. aeruginosa resistance, linked to a major reduction in the prevalence of XDR strains, is encouraging, the negative counterpart is the increase in the proportion of XDR strains producing carbapenemases, associated to the significant advance of the concerning world-wide disseminated hypervirulent high-risk clone ST235. Continued high-resolution surveillance, integrating phenotypic and genomic data, is necessary for understanding resistance trends and analyzing the impact of national plans on antimicrobial resistance. Funding: MSD and the Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación and Unión Europea—NextGenerationEU