Publications by authors named "Olivier Fontaine"

Aqueous biphasic systems (ABSs) with water-in-salt electrolytes are gaining significant attention for their role in aqueous biphasic interphase studies, particularly in energy storage devices. Aqueous salt-salt biphasic electrolytes are considered a promising alternative to replace traditional liquid electrolytes commonly used in battery technologies, for example, membrane-less redox flow batteries, owing to their low cost and high ionic conductivity. However, the stability of the interphase over time must be considered, as it can impact the long-term electrochemical performance in various applications.

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Background: Diarrhoeal disease poses a significant global health challenge, especially in children under three years old. Despite the effectiveness of oral rehydration therapy (ORT), its adoption remains low. Glucose-based ORS (GORS) is the standard, but novel formulations like glucose-free amino acid-based VS002A have emerged as potential alternatives.

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In recent decades, more than 100,000 scientific articles have been devoted to the development of electrode materials for supercapacitors and batteries. However, there is still intense debate surrounding the criteria for determining the electrochemical behavior involved in Faradaic reactions, as the issue is often complicated by the electrochemical signals produced by various electrode materials and their different physicochemical properties. The difficulty lies in the inability to determine which electrode type (battery vs.

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A water-in-salt electrolyte is a highly concentrated aqueous solution (i.e., 21 mol LiTFSI in 1 kg H O) that reduces the number of water molecules surrounding salt ions, thereby decreasing the water activity responsible for decomposition.

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Superconcentrated aqueous electrolytes have recently emerged as a new class of electrolytes, called water-in-salt electrolytes. They are distinguished, in both weight and volume, by a quantity of salt greater than water. Currently, these electrolytes are attracting major interest, particularly for application in aqueous rechargeable batteries.

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The essence of any electrochemical system is engraved in its electrical double layer (EDL), and we report its unprecedented reorganization by the structural isomerism of molecules, with a direct consequence on their energy storage capability. Electrochemical and spectroscopic analyses in combination with computational and modelling studies demonstrate that an attractive field-effect due to the molecule's structural-isomerism, in contrast to a repulsive field-effect, spatially screens the ion-ion coulombic repulsions in the EDL and reconfigures the local density of anions. In a laboratory-level prototype supercapacitor, those with β-structural isomerism exhibit nearly 6-times elevated energy storage compared to the state-of-the-art electrodes, by delivering ∼535 F g at 1 A g while maintaining high performance metrics even at a rate as high as 50 A g.

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Aqueous batteries are regaining interest, thanks to the extended working stability voltage window in a highly concentrated electrolyte, namely the water-in-salt electrolyte. A solid-electrolyte interphase (SEI) forms on the negative electrode to prevent water access to the electrode surface. However, we further reported that the formed SEI layer was not uniform on the surface of the glassy carbon electrode.

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Ionic liquids generally display peculiar structural features that impact their physical properties, such as the formation of polar and apolar domains. Recently, ionic liquids functionalized with anthraquinone and TEMPO redox groups were shown to increase the energy storage performance of supercapacitors, but their structure has not yet been characterized. In this work, we use polarizable molecular dynamics to study the nanostructuration of such biredox ionic liquids.

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Article Synopsis
  • Conducting polymers are promising materials for micro-electrochemical energy storage, but there are limited methods to characterize their nanostructured electrodes.
  • Scanning electrochemical microscopy (SECM) offers a new in situ technique to assess and accelerate the degradation processes of these conducting polymers.
  • The SECM method not only shortens the degradation study time significantly but also models the degradation rate using Comsol Multiphysics, providing detailed insights into the underlying phenomena.
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Background: Diarrhea is the second deadliest disease for under-five children globally and the situation is more serious in developing countries. Oral rehydration solution (ORS) is being used as a standard treatment for acute watery diarrhea for a long time. Our objective is to compare the efficacy of amino acid-based ORS "VS002A" compared to standard glucose-based WHO-ORS in infants and young children suffering from acute non-cholera watery diarrhea.

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Whiteflies are one of the major pests of tomato under greenhouses, and their control partly relies on biocontrol strategies. Among those biocontrol agents, parasitoids or predators are widely used. However, the introduction of a biocontrol agent in a new area is not trivial.

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Aprotic alkali metal-O batteries face two major obstacles to their chemistry occurring efficiently, the insulating nature of the formed alkali superoxides/peroxides and parasitic reactions that are caused by the highly reactive singlet oxygen (O). Redox mediators are recognized to be key for improving rechargeability. However, it is unclear how they affect O formation, which hinders strategies for their improvement.

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The interfacial electrochemistry of reversible redox molecules is central to state-of-the-art flow batteries, outer-sphere redox species-based fuel cells, and electrochemical biosensors. At electrochemical interfaces, because mass transport and interfacial electron transport are consecutive processes, the reaction velocity in reversible species is predominantly mass-transport-controlled because of their fast electron-transfer events. Spatial structuring of the solution near the electrode surface forces diffusion to dominate the transport phenomena even under convective fluid-flow, which in turn poses unique challenges to utilizing the maximum potential of reversible species by either electrode or fluid characteristics.

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Water-in-salt electrolytes based on highly concentrated bis(trifluoromethyl)sulfonimide (TFSI) promise aqueous electrolytes with stabilities nearing 3 V. However, especially with an electrode approaching the cathodic (reductive) stability, cycling stability is insufficient. While stability critically relies on a solid electrolyte interphase (SEI), the mechanism behind the cathodic stability limit remains unclear.

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Background And Purpose: Age-related macular degeneration (AMD) is a complex neurodegenerative disease treated by anti-VEGF intravitreal injections. As inflammation is potentially involved in retinal degeneration, the pro-inflammatory kallikrein-kinin system is a possible alternative pharmacological target. Here, we investigated the effects of anti-VEGF and anti-B receptor treatments on the inflammatory mechanisms in a rat model of choroidal neovascularization (CNV).

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The grafting of molecular monolayers is critical for the functionalization of surfaces. In molecular electrochemistry, the surface modification of electrodes and the way molecules are attached to the electrode surface are highly critical to electron transfers and electrochemical reactions. In this paper, sub-monolayers were covalently grafted onto glassy carbon (GC) electrodes via Diels-Alder cycloaddition with two soluble dienophiles, that is, propargyl bromide and ethynyl ferrocene.

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The Program for the Control of Diarrheal Diseases (CDD) of the World Health Organization (WHO) was created in 1978, the year the Health for All Strategy was launched at the Alma Ata International Conference on Primary Health Care. CDD quickly became one of the pillars of this strategy, with its primary goal of reducing diarrhea-associated mortality among infants and young children in developing countries. WHO expanded the previous cholera-focused unit into one that addressed all diarrheal diseases, and uniquely combined support to research and to national CDD Programs.

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Background: Childhood diarrhea deaths have declined more than 80% from 1980 to 2015, in spite of an increase in the number of children in low- and middle-income countries (LMIC). Possible drivers of this remarkable accomplishment can guide the further reduction of the half million annual child deaths from diarrhea that still occur.

Methods: We used the Lives Saved Tool, which models effects on mortality due to changes in coverage of preventive or therapeutic interventions or risk factors, for 50 LMIC to determine the proximal drivers of the diarrhea mortality reduction.

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This study aims to present information on the surveillance, policy developments, and implementation of physical activity policies in the 28 European Union (EU) countries. Data was collected on the implementation of the EU Recommendation on health-enhancing physical activity (HEPA) across sectors. In line with the monitoring framework proposed in the Recommendation, a questionnaire was designed to capture information on 23 physical activity indicators.

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Rechargeable Li-O batteries have amongst the highest formal energy and could store significantly more energy than other rechargeable batteries in practice if at least a large part of their promise could be realized. Realization, however, still faces many challenges than can only be overcome by fundamental understanding of the processes taking place. Here, we review recent advances in understanding the chemistry of the Li-O cathode and provide a perspective on dominant research needs.

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Owing to the transient nature of the intermediates formed during the oxygen evolution reaction (OER) on the surface of transition metal oxides, their nature remains largely elusive by the means of simple techniques. The use of chemical probes is proposed, which, owing to their specific affinities towards different oxygen species, unravel the role played by these species on the OER mechanism. For that, tetraalkylammonium (TAA) cations, previously known for their surfactant properties, are introduced, which interact with the active oxygen sites and modify the hydrogen bond network on the surface of OER catalysts.

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Kinetics of electrochemical reactions are several orders of magnitude slower in solids than in liquids as a result of the much lower ion diffusivity. Yet, the solid state maximizes the density of redox species, which is at least two orders of magnitude lower in liquids because of solubility limitations. With regard to electrochemical energy storage devices, this leads to high-energy batteries with limited power and high-power supercapacitors with a well-known energy deficiency.

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A mild and simple way to prepare stable aqueous colloidal suspensions of composite particles made of a cellulosic material (Sigmacell cellulose) and multiwalled carbon nanotubes (MWCNTs) is reported. These suspensions can be dried and redispersed in water at pH 10.5.

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Nanostructured TiO2 and TiO2@C nanocomposites were prepared directly from urea-impregnated cellulose by a simple reaction/diffusion process and evaluated as negative electrode materials for Li and Na batteries. By direct treatment with TiCl4 under anhydrous conditions, the urea impregnation of cellulose impacts both the TiO2 morphology and the carbon left by cellulose after pyrolysis. Hierarchical TiO2 structures with a flower-like morphology grown from-and-at the surface of the cellulose fibers are obtained without any directing agent.

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