Response to J-Y. Maillard: Are amine-only-containing products sporicidal?

J-Y. Maillard made a very important point in reflecting that, during efficacy testing of disinfectants, demonstration of neutralization of the biocidal effect at the end of contact time is crucial. We also agree that ‘It is thus puzzling and possibly concerning that products containing amines alone are being used as sporicides in healthcare setting

Calciothermic Synthesis of Very Fine, Hydrogenated Ti and Ti–Nb Powder for Biomedical Applications

Due to their excellent biocompatibility, titanium and titanium–niobium alloys are especially interesting for biomedical applications. With regard to favorable near-net shape production, Ti powder synthesis is the key hurdle. Extensive research has been in progress for alternative synthesis methods since decades. Herein, an efficient alternative method to the conventional powder production process to prepare spherical powders with very small sizes (<45 μm) for high-strength materials is shown. Very fine, hydrogenated Ti and Ti–Nb alloy powders are stable in air and are synthesized by calciothermic reduction in hydrogen. The herein presented reduction using CaH2 starts directly from the oxides instead of chlorides. Correlations of size and morphology of the as-synthesized TiH2 and (Ti,Nb)H2 powders with the precursors (TiO2, Nb2O5, and CaH2) are illustrated and are used to tailor the desired powders

Ultra-fine grained Nd–Fe–B by high pressure reactive milling and desorption

This paper reports on the grain refinement in dynamic hydrogenation disproportionation desorption and recombination (d-HDDR) processed Nd-rich Nd2Fe14B and stoichiometric Nd2Fe14B powders using high pressure reactive milling (HPRM) followed by a subsequent desorption and recombination. In contrast to the dynamic-HDDR processed anisotropic powder with a grain size of the Nd2Fe14B phase of 300 nm, the new approach yields a further reduction of the Nd2Fe14B1 grain size to less than 70 nm. Nd-rich Nd2Fe14B powder produced by HPRM and subsequent desorption exhibits a coercivity μ0iHc=1.35 T and a remanence of 0.80 T. In the stoichiometric material, the reduction of the Nd-content leads to an increase in remanence to 0.85 T. Additionally, it is demonstrated that highly anisotropic powders can also be obtained by dynamic-HDDR processing of stoichiometric Nd2Fe14B powders

QENS investigation of proton confined motions in hydrated perfluorinated sulfonic membranes and self-assembled surfactants

International audienceWe report on QuasiElastic Neutron Scattering (QENS) investigations of the dynamics of protons and water molecules confined in nanostructured perfluorinated sulfonic acid (PFSA) materials, namely a commercial Aquivion membrane and the perfluorooctane sulfonic acid (PFOS) surfactant. The former is used as electrolyte in low-temperature fuel cells, while the latter forms mesomorphous self-assembled phases in water. The dynamics was investigated as a function of the hydration level, in a wide time range by combining time-of-flight and backscattering incoherent QENS experiments. Analysis of the quasielastic broadening revealed for both systems the existence of localized translational diffusive motions, fast rotational motions and slow hopping of protons in the vicinity of the sulfonic charges. The characteristic times and diffusion coefficients have been found to exhibit a very similar behaviour in both membrane and surfactant structures. Our study provides a comprehensive picture of the proton motion mechanisms and the dynamics of confined water in model and real PFSA nanostructures

The European tiered approach for virucidal efficacy testing – rationale for rapidly selecting disinfectants against emerging and re-emerging viral diseases

When facing an emerging virus outbreak such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a quick reaction time is key to control the spread. It takes time to develop antivirals and vaccines, and implement vaccination campaigns. Therefore, preventive measures such as rapid isolation of cases and identification and early quarantine of cases’ close contacts—as well as masks, physical distancing, hand hygiene, surface disinfection and air control—are crucial to reduce the risk of transmission. In this context, disinfectants and antiseptics with proven efficacy against the outbreak virus should be used. However, biocidal formulations are quite complex and may include auxiliary substances such as surfactants or emollients in addition to active substances. In order to evaluate disinfectants’ efficacy objectively, meaningful efficacy data are needed. Therefore, the European Committee for Standardisation technical committee 216 ‘Chemical disinfectants and antiseptics’ Working Group 1 (medical area) has developed standards for efficacy testing. The European tiered approach grades the virucidal efficacy in three levels, with corresponding marker test viruses. In the case of SARS-CoV-2, disinfectants with proven activity against vaccinia virus, the marker virus for the European claim ‘active against enveloped viruses’, should be used to ensure effective hygiene procedures to control the pandemic.Peer Reviewe

Nanostructure and Transport Properties of Proton Conducting Self-Assembled Perfluorinated Surfactants: A Bottom-Up Approach toward PFSA Fuel Cell Membranes

International audienceA comprehensive study of commercially available and newly synthesized proton conducting perfluorinated sulfonic acid (PFSA) surfactantsand polymeric systems is reported, specially designed in a bottom-up search to improve the basic understanding of PFSA polymers used as benchmark electrolytes in fuel cells. Hydration-dependent mesomorphous phases are formed by the self-assembly of these molecules in water. The impact of the hydrophobic chain length, the density of charge, the molecular architecture on the nanostructure, and the dynamics of confined water were studied by combining small-angle X-ray scattering, quasielastic neutron scattering, and pulsed-field gradient NMR. We introduce a hydration-dependent structural parameter, dw (mean size of water domains), that allows to establish the structure−transport relationship in PFSA materials. This multiscale study reveals that (i) the dynamical behavior of confined protons and water molecules are rather insensitive to the topology of the host matrix and (ii) the main parameter driving the performance of fuel cell electrolytes is the total water content required for swelling the domains above a value of 1 nm

Multiscale Water Dynamics in a Fuel Cell by Operando Quasi Elastic Neutron Scattering

International audienceWater and proton dynamics in an functioning proton exchange membrane fuel cell (PEMFC) were probed with quasi-elastic neutron scattering (QENS). By operating the specially designed neutron-transparent fuel cell in a “proton pump” mode, we were able to perfectly control the membrane hydration, which allowed us to discriminate the impact of electric field on water molecules diffusivity from pure hydration effects. By cross-analyzing the fuel cell QENS spectra taken over extended range of time scales, we demonstrate that protons exhibit the same dynamical behavior as in an ex-situ membrane at the same level of hydration, e.g., slow hopping motions of adsorbed protons (mostly H3O+) and subdiffusive confined motions of hydration protons (H2O). These mechanisms are maintained on applying a current up to 0.1 A/cm2. With this work, we establish the applicability of QENS to monitor in situ the molecular dynamics in PEMFC, and prove that knowledge extracted from ex situ proton conducting electrolytes can be transposed to the full operando cells