Unveiling LiTFSI Precipitation as a Key Factor in Solid Electrolyte Interphase Formation in Li-Based Water-in-Salt Electrolytes.

A water-in-salt electrolyte is a highly concentrated aqueous solution (i.e., 21 mol LiTFSI in 1 kg H2 O) that reduces the number of water molecules surrounding salt ions, thereby decreasing the water activity responsible for decomposition. This electrolyte widens the electrochemical stability window via the formation of a solid electrolyte interphase (SEI) at the electrode surface. However, using high concentration electrolytes in Li-ion battery technology to enhance energy density and increase cycling stability remains challenging. A parasitic reaction, called the hydrogen evolution reaction, occurs when the reaction operates at a lower voltage. It is demonstrated here that a micrometric white layer is indeed a component of the SEI layer, not just on the nanoscale, through the utilization of an operando high-resolution optical microscope. The results indicate that LiTFSI precipitation is the primary species present in the SEI layer. Furthermore, the passivation layer is found to be dynamic since it dissolves back into the electrolyte during open circuit voltage.

Local Degradation of PEDOT:PSS on Silicon Nanostructures Using Scanning Electrochemical Microscopy.

Conducting polymers show attractive characteristics as electrode materials for micro-electrochemical energy storage (MEES). However, there is a lack of characterization techniques to study conjugated/conducting polymer-based nanostructured electrodes. Here, scanning electrochemical microscopy (SECM) is introduced as a new technique for in situ characterization and acceleration of degradation processes of conducting polymers. Electrodes of PEDOT:PSS on flat silicon, silicon nanowires (SiNWs) and silicon nanotrees (SiNTrs) are analyzed by SECM in feedback mode with approach curves and chronoamperometry. The innovative degradation method using SECM reduces the time required to locally degrade polymer samples to a few thousand seconds, which is significantly shorter than the time usually required for such studies. The degradation rate is modeled using Comsol Multiphysics. The model provides an understanding of the phenomena that occur during degradation of the polymer electrode and describes them using a mathematical constant A0 and a time constant τ.

Continuous medium approach to approximate the high concentrated aqueous electrolyte with different types of electrochemical structure.

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. These electrolytes have only a small amount of free water due to an ultrahigh salt concentration. Consequently, the electrochemical stability window of water is wider than the predicted thermodynamic value of 1.23 V. Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) have been shown to be shifted to more negative and positive potentials, respectively. The decrease in free water population is recognized as being involved in the increase in the electrochemical stability window of water. Here, we study the quantitative contribution of the decrease in the free water molecule concentration to the permittivity of the solution and of the activity of water to the OER and HER overpotentials when the salt concentration increases. We compare our model with that of Kornyshev and get three types of electrolyte structures: diluted, gradient of water contents, and aggregation. The theoretical calculation of the redox potentials of the OER and HER is compared with the experimentally determined electrochemical properties of aqueous LiTFSI electrolytes.

Life history parameters and predation capacities of Nesidiocoris volucer: a new biological control agent for tomato crop.

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. For that reason, we investigated the use of a tropical native mirid, Nesidiocoris volucer (Hemiptera: Miridae), for the biological control of whiteflies among other insect pests on tomato crops under greenhouses in the subtropical island of La Réunion, France. Nesidiocoris volucer life history traits and plant injury were examined. Nymphs developed and survived between 15 and 30°C and required on average 49.41 days at 15°C and on average 10.50 days at 30°C to develop (nymph survival >94%). At 25°C, each female produced on average 65 eggs. Nesidiocoris volucer was able to feed on several prey species, but performed better on whiteflies than on spider mites or thrips. No N. volucer feeding injury was observed on tomato. Nesidiocoris volucer has also been found in tropical countries of Africa, and we believe that the data presented on this natural enemy could be of great importance for the biocontrol of whiteflies in tropical areas.

Competitive Salt Precipitation/Dissolution During Free-Water Reduction in Water-in-Salt Electrolyte.

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. Now, two distinct reduction potentials are revealed for the chemical environments of free and bound water and that both contribute to SEI formation. Free water is reduced about 1 V above bound water in a hydrogen evolution reaction (HER) and is responsible for SEI formation via reactive intermediates of the HER; concurrent LiTFSI precipitation/dissolution establishes a dynamic interface. The free-water population emerges, therefore, as the handle to extend the cathodic limit of aqueous electrolytes and the battery cycling stability.

Biredox ionic liquids with solid-like redox density in the liquid state for high-energy supercapacitors.

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. For such devices the ideal system should endow the liquid state with a density of redox species close to the solid state. Here we report an approach based on biredox ionic liquids to achieve bulk-like redox density at liquid-like fast kinetics. The cation and anion of these biredox ionic liquids bear moieties that undergo very fast reversible redox reactions. As a first demonstration of their potential for high-capacity/high-rate charge storage, we used them in redox supercapacitors. These ionic liquids are able to decouple charge storage from an ion-accessible electrode surface, by storing significant charge in the pores of the electrodes, to minimize self-discharge and leakage current as a result of retaining the redox species in the pores, and to raise working voltage due to their wide electrochemical window.

Chemical Recognition of Active Oxygen Species on the Surface of Oxygen Evolution Reaction Electrocatalysts.

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. Combining chemical probes with isotopic and pH-dependent measurements, it is further demonstrated that the introduction of iron into amorphous Ni oxyhydroxide films used as model catalysts deeply modifies the proton exchange properties, and therefore the OER mechanism and activity.

Efficacy of early neonatal supplementation with vitamin A to reduce mortality in infancy in Haryana, India (Neovita): a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Vitamin A supplementation in children aged 6 months to 5 years has been shown to reduce mortality. The efficacy of neonatal supplementation with vitamin A to reduce mortality in the first 6 months of life is plausible but not established. We aimed to assess the efficacy of neonatal oral supplementation with vitamin A to reduce mortality between supplementation and 6 months of age. METHODS: We undertook an individually randomised, double-blind, placebo-controlled trial in Haryana, India. We identified pregnant women through a surveillance programme undertaken every 3 months of all female residents in two districts of Haryana, India, aged 15-49 years, and screened every identified livebirth. Eligible participants were neonates whose parents consented to participate, were likely to stay in the study area until at least 6 months of age, and were able to feed orally at the time of enrolment. Participants were randomly assigned to receive oral capsules containing vitamin A (retinol palmitate 50,000 IU plus vitamin E 9·5-12·6 IU) or placebo (vitamin E 9·5-12·6 IU) within 72 h of birth. Randomisation was in blocks of 20 according to a randomisation list prepared by a statistician not otherwise involved with the trial. Investigators, participants' families, and the data analysis team were masked to treatment allocation. The primary outcome was mortality between supplementation and 6 months of age. Analysis included all participants assigned to study groups. This trial is registered with ClinicalTrials.gov, number NCT01138449, and the Indian Council of Medical Research Clinical Trial Registry, number CTRI/2010/091/000220. FINDINGS: Between June 24, 2010, and July 1, 2012 we screened 47,777 neonates and randomly assigned 44,984 to receive vitamin A (22,493) or placebo (22,491). Between supplementation and 6 months of age, 656 infants died in the vitamin A group compared with 726 in the placebo group (29·2 per 1000 vs 32·3 per 1000; difference -3·1 per 1000, 95% CI -6·3 to 0·1; risk ratio 0·90, 95% CI 0·81 to 1·00). We noted no significant interactions between the intervention effect and sex on mortality at 6 months (p=0·409). Supplementation with 50,000 IU vitamin A within the first 72 h of life was generally safe and well tolerated, with the exception of a small excess risk of transient bulging fontanelle (205 cases in the vitamin A group confirmed by physician vs 80 cases in the placebo group, risk ratio 2·56 [95% CI 1·98-3·32]). INTERPRETATION: The findings of this study, done in a population in which vitamin A deficiency is a moderate public health problem, are consistent with a modest reduction in mortality between supplementation and 6 months of age. These findings must be viewed together with similar trials in other populations to enable determination of appropriate public health policy. FUNDING: Bill & Melinda Gates Foundation to WHO.

Multiwalled Carbon Nanotube/Cellulose Composite: From Aqueous Dispersions to Pickering Emulsions.

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. Starting with rather crude initial materials, commercial Sigmacell cellulose and MWCNTs, a significant fraction of composite dispersed in water could be obtained. The solid composites and their colloidal suspensions were characterized by electronic microscopy, thermal analyses, FTIR and Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and light scattering. The composite particles consist of tenuous aggregates of CNTs and cellulose, several hundred nanometers large, and are composed of 55 wt % cellulose and 45 wt % CNTs. Such particles were shown to stabilize cyclohexane-in-water emulsions. The adsorption and the elasticity of the layer they form at interface were characterized by the pendant drop method. The stability of the oil-in-water emulsions was attributed to the formation of an elastic network of composite particles at interface. Cyclohexane droplet diameters could be tuned from 20 to 100 µm by adjusting the concentration of composite particles. This behavior was attributed to the limited coalescence phenomenon, just as expected for Pickering emulsions. Interestingly, cyclohexane droplets were stable over time and sustained pH modifications over a wide range, although acidic pH induced accelerated creaming. This study points out the possibility of combining crude cellulose and MWCNTs through a simple process to obtain colloidal systems of interest for the design of functional conductive materials.

Demonstration of the effectiveness of zinc in diarrhoea of children living in Switzerland.

UNLABELLED: We designed a double-blinded randomized clinical trial of zinc (10 or 20 mg of zinc sulphate for 2-5 month-old or 6-59 month-old children, respectively, during 10 days) vs. placebo in otherwise healthy children aged 2 months to 5 years who presented with acute diarrhoea (i.e. ≥3 stools/day for less than 72 h). Eighty-seven patients (median age 14 months; range 3.1-58.3) were analysed in an intention-to-treat approach. Forty-two patients took zinc and 45 placebo. There was no difference in the duration nor in the frequency of diarrhoea, but only 5% of the zinc group still had diarrhoea at 120 h of treatment compared to 20% in the placebo group (P = 0.05). Thirty-one patients (13 zinc and 18 placebo) were available for per-protocol analyses. The median (IQR) duration of diarrhoea in zinc-treated patients was 47.5 h (18.3-72) and differed significantly from the placebo group (median 76.3; IQR 52.8-137) (P = 0.03). The frequency of diarrhoea was also lower in the zinc group (P = 0.02). CONCLUSION: zinc treatment decreases the frequency and severity of diarrhoea in children aged 2 months to 5 years living in Switzerland. However, the intention-to-treat analysis reveals compliance issues that question the proper duration of treatment and the choice of optimal pharmaceutical formulation.

Delivering nanomedicines to patients: a practical guide.

This is a perspective on the current state of development of nanomedicines in Europe. The view is expressed that a much higher translational success rate could be achieved, with rewards for all stakeholders, if researchers understood the industrial decision points required for new drugs. Getting a drug through the clinic will not help patients unless it is developable by industry. This article is written in the hope that it will help researchers and SMEs to decide where they are in the established process, whether they are making progress and to determine what to do next. It attempts to map the early stages from ideation to first (time) in man (FIM). FROM THE CLINICAL EDITOR: The field of nanomedicine has come a long way in the past decade. The overall dream of any researcher in this field remains the realization of concept to clinical product. In this paper, the authors outlined for the readers, the underlying problems and actions that need to be done, so that current challenges can be solved.

Electropolymerization of polypyrrole by bipolar electrochemistry in an ionic liquid.

Bipolar electrochemistry has been recently explored for the modification of conducting micro- and nanoobjects with various surface layers. So far, it has been assumed that such processes should be carried out in low-conductivity electrolytes in order to be efficient. We report here the first bipolar electrochemistry experiment carried out in an ionic liquid, which by definition shows a relatively high conductivity. Pyrrole has been electropolymerized on a bipolar electrode, either in ionic liquid or in acetonitrile. The resulting polymer films were characterized by scanning electron microscopy and by contact profilometry. We demonstrate that the films obtained in an ionic liquid are thinner and smoother than the films synthesized in acetonitrile. Furthermore, a well-defined band of polypyrrole can be obtained in ionic liquid, in contrast to acetonitrile for which the polypyrrole film is present on the whole anodic part of the bipolar electrode.

Capacitive tendency concept alongside supervised machine-learning toward classifying electrochemical behavior of battery and pseudocapacitor materials.

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. pseudocapacitor) these materials belong to via simple binary classification. To overcome this difficulty, we apply supervised machine learning for image classification to electrochemical shape analysis (over 5500 Cyclic Voltammetry curves and 2900 Galvanostatic Charge-Discharge curves), with the predicted confidence percentage reflecting the shape trend of the curve and thus defined as a manufacturer. It's called "capacitive tendency". This predictor not only transcends the limitations of human-based classification but also provides statistical trends regarding electrochemical behavior. Of note, and of particular importance to the electrochemical energy storage community, which publishes over a hundred articles per week, we have created an online tool to easily categorize their data.

Assessing safety and efficacy of a novel glucose-free amino acid oral rehydration solution for watery diarrhea management in children: a randomized, controlled, phase III trial.

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. This study aimed to compare the safety and efficacy of VS002A against the standard WHO-ORS in treating non-cholera acute watery diarrhoea in children. Methods: A triple-blind, randomized trial enrolled 310 male infants and children aged 6-36 months, who were assigned to receive WHO-ORS or VS002A over a 16-month period, from June 2021 to September 2022. Both groups received standard of care, including zinc supplementation. The Primary study outcome measured was the duration of diarrhoea. Secondary outcomes included stool output, treatment failure and adverse events. Exploratory endpoints included urinary output, body weight changes, blood biochemistry, stool microbiology and gut health biomarkers. Findings: Both VS002A and WHO-ORS were well-tolerated with a low adverse event rate. While not different statistically (p = 0.10), duration of diarrhoea was shorter in children treated with VS002A vs. WHO-ORS (65.4 h vs. 72.6 h). Similarly, stool output was also lower vs. WHO-ORS in children treated with VS002A, though not statistically different (p = 0.40). Serum citrulline levels, an indicator of gut health, were higher in the VS002A group at 24 h suggesting a potential protective effect (p = 0.06). Interpretation: The findings of this study support the non-inferiority of VS002A, a glucose-free amino acid-based ORS compared to the WHO-ORS standard of care. VS002A was shown to be safe and effective in treating non-cholera acute watery diarrhoea in young children. VS002A may offer advantages in pathogen-driven diarrhoea, supported by trends toward a lower duration of diarrhoea and stool output within the per protocol group. Furthermore, individuals with prolonged diarrhoea, severe malnutrition, environmental enteric dysfunction or have issues with obesity or insulin resistance, could benefit from a glucose-free ORS. This research contributes to addressing the persistent challenge of childhood diarrhoea by presenting an alternative glucose-free ORS formulation with potential advantages in select scenarios, offering a promising avenue for improving paediatric diarrhoea management worldwide. Funding: The study was funded by Entrinsic Bioscience, LLC., Norwood, MA, USA.

Measuring coverage in MNCH: current indicators for measuring coverage of diarrhea treatment interventions and opportunities for improvement.

Diarrhea morbidity and mortality remain important child health problems in low- and middle-income countries. The treatment of diarrhea and accurate measurement of treatment coverage are critical if child mortality is going to continue to decline. In this review, we examine diarrhea treatment coverage indicators collected in two large-scale community-based household surveys--the Demographic and Health Surveys (DHS) and Multiple Indicator Cluster Surveys (MICS). Current surveys do not distinguish between children with mild diarrhea episodes and those at risk for dehydration. Additional disease severity questions may improve the identification of cases of severe diarrhea but research is needed to identify indicators with the highest sensitivity and specificity. We also review the current treatment indicators in these surveys and highlight three areas for improvement and research. First, specific questions on fluids other than oral rehydration salts (ORS) should be eliminated to refocus the treatment of dehydration on ORS and to prevent confusion between prevention and treatment of dehydration. Second, consistency across surveys and throughout translations is needed for questions about the caregiver behavior of "offering" the sick child fluid and food. Third, breastfeeding should be separated from other fluid and food questions to capture the frequency and duration of nursing sessions offered during the illness. Research is also needed to assess the accuracy of the current zinc indicator to determine if caregivers are correctly recalling zinc treatment for current and recent diarrhea episodes.

Adequacy of child anthropometric indicators for measuring nutritional stress at population level: a study from Niakhar, Senegal.

OBJECTIVE: To compare the responsiveness of different anthropometric indicators for measuring nutritional stress among children in developing countries. DESIGN: Growth was studied within 6-month intervals in a rural Senegalese community during one dry and two rainy (hungry) seasons. Responsiveness was defined as the change divided by the standard deviation of each anthropometric indicator. Contrast was defined as the difference in responsiveness between dry and rainy seasons. SETTING: The study was conducted in Niakhar, a rural area of Senegal under demographic surveillance, with contrasted food and morbidity situations between rainy and dry seasons. SUBJECTS: Some 5000 children under 5 years of age were monitored at 6-month intervals in 1983­1984. The present analysis was carried out on a sub-sample of children aged 6­23 months with complete measures, totalling 2803 children-intervals. RESULTS: In both univariate and multivariate analysis, mid-upper arm circumference was found to be more responsive to nutritional stress than the commonly used weight-for-height Z-score (contrast = -0.64 for mid-upper arm circumference v. -0.53 for weight-for-height Z-score). Other discriminant indicators were: muscle circumference, weight-for-height, BMI and triceps skinfold. Height, head circumference and subscapular skinfold had no discriminating power for measuring the net effect of nutritional stress during the rainy season. CONCLUSIONS: The use of mid-upper arm circumference for assessing nutritional stress in community surveys should be considered and preferred to other nutritional indicators. Strict standardization procedures for measuring mid-upper arm circumference are required for optimal use.

Nanostructural Organization in a Biredox Ionic Liquid.

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. We show that TEMPO nitroxyl functions tend to aggregate, while the anthraquinone groups favor stacked arrangements. The latter eventually percolate through the whole liquid, which sheds some light on the mechanisms at play within biredox ionic liquid-based supercapacitors.

Visualizing Water Reduction with Diazonium Grafting on a Glassy Carbon Electrode Surface in a Water-in-Salt Electrolyte.

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. The SEI after passivation will also show degradation during the remaining time of open-circuit voltage (OCV); hence, it calls for a more stable passivation layer to cover the electrode surface. Here, a surface modification was successfully achieved via artificial diazonium grafting using monomers, such as poly(ethylene glycol), α-methoxy, ω-allyloxy (PEG), and allyl glycidyl cyclocarbonate (AGC), on glassy carbon. Physical and electrochemical measurements indicated that the hydrophobic layer composed of PEG or AGC species was well grafted on the electrode surface. The grafted hydrophobic coatings could protect the electrode surface from the water molecules in the bulk electrolyte and then suppress the free water decomposition (from LSV) but still migrating lithium ions. Furthermore, multiple cycles of CV with one-hour resting OCV identified the good stability of the hydrophobic grafting layer, which is a highlight compared with our precious work. These findings relying on the diazonium grafting design may offer a new strategy to construct a stable artificial SEI layer that can well protect the electrode surface from the free water molecule.

Unprecedented energy storage in metal-organic complexes via constitutional isomerism.

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 ß-structural isomerism exhibit nearly 6-times elevated energy storage compared to the state-of-the-art electrodes, by delivering ∼535 F g-1 at 1 A g-1 while maintaining high performance metrics even at a rate as high as 50 A g-1. The elucidation of the decisive role of structural isomerism in reconfiguring the electrified interface represents a major step forward in understanding the electrodics of molecular platforms.