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Rapid and cost-effective diagnostic tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have become a critical and valuable weapon for the coronavirus disease 2019 (COVID-19) pandemic response. SARS-CoV-2 invasion is primarily mediated by human angiotensin-converting enzyme 2 (hACE2). Recent developments in ACE2-based SARS-CoV-2 detection modalities accentuate the potential of this natural host-virus interaction for developing point-of-care (POC) COVID-19 diagnostic tools and devices. Although research on harnessing ACE2 for SARS-CoV-2 detection is in its infancy, some interesting biosensing devices have been developed, showing the commercial viability of this intriguing new approach. The exquisite performance of the reported ACE2-based COVID-19 biosensors provides opportunities for researchers to develop rapid detection tools suitable for testing at points of entry, workplaces, or congregate scenarios in order to effectively implement pandemic control and management plans. However, to be considered as an emerging approach, the rationale for ACE2-based biosensing needs to be critically and comprehensively surveyed and discussed. Herein, we review the current status of ACE2-based detection methods, the signal transduction principles in ACE2 biosensors and the development trend in the future. We discuss the challenges to development of ACE2-biosensors and delineate prospects for their use, along with recommended solutions and suggestions

Additional file 12: Review history.

Electrocatalytic hydrodechlorination is deemed as a promising environmental remediation technology for fast and effective detoxification of halogenated antibiotic pollutants. In this study, a novel nickel (Ni) foam electrode decorated by ultrafine palladium (Pd) nanoparticles (denoted as Pd@Ni-foam) was reported for electrocatalytic dechlorination of florfenicol (FLO, a typical antibiotic). The Pd@Ni-foam electrode was synthesized via a facile and simple spontaneous galvanic replacement of surface Ni atoms of Ni foam with Pd precursor. The obtained Pd@Ni-foam catalyst showed an excellent performance on electrochemical dechloridation of FLO. The dechloridation efficiency of FLO (20 mg L−1) reached 99.5% with the dechloridation rate as fast as 16.58 mg min−1 at cathode potential of –1.2 V (vs. saturated Ag/AgCl), which far prevailed over pure Ni foam (2.63 mg min−1) and commercial Pd/C (11.32 mg min−1). The reaction rate constant (0.044 min−1) of FLO dechloridation at Pd@Ni-foam electrode was 44 and 4.4 times higher than that of pure Ni-foam (0.001 min−1) and commercial Pd/C (0.010 min−1), respectively. The excellent electrocatalysis for FLO dechloridation of Pd@Ni-foam cathode is ascribed to the 3D self-supported Ni-foam frame for mass transfer enhancement and the formation of Pd-Ni micro-interfaces leading to the high utilization of atomic H*. Furthermore, the toxicity assessment showed that the antibacterial activity of FLO was complete elimination after electrocatalytic dechlorination process.

This work focuses on modeling the microstructure evolution induced by SMAT in TWIP and/or TRIP steels. The features of the generated gradient microstructure of a 304L TWIP/TRIP steel are characterized by SEM, XRD, and nanoindentation. Nanoindentation is applied on different layers for the investigation of the mechanical properties of the gradient microstructure. Based on the experimental results, a dislocation density model considering the influence of twinning and martensitic transformation of TWIP/TRIP steel is proposed to investigate the effect of SMAT controlling parameters. Then the dislocation density of the austenite and that of the martensite as well as the volume fraction of twinning and martensitic transformation during impact loading is numerically evaluated using a full finite element model. Afterwards, to study the evolution of the damage during the SMAT process, the damage was introduced in the dislocation density model. Finally, a dislocation density based visco-elastoplastic model considering the effect of grain size, dislocation density, twin, and strain rate was proposed to further understand the effect of impact loadings on the mechanical properties of TWIP/TRIP steel with gradient microstructure based on the results of nanoindentation tests. Then to study the overall elastoplastic response of the SMATed material, the rule of mixtures is used by considering the gradient material as a gradient structure consisting of different layers with distinct microstructures and mechanical properties.; Ce travail est centré sur la modélisation de l’évolution de microstructures induite par le procédé SMAT pour des aciers TWIP/TRIP. Les caractéristiques de base d’un acier TWIP/TRIP sont mises en évidence par MEB, DRX et nanoindentation. La nanoindentation est appliquée sur différentes couches pour l’étude des propriétés mécaniques du matériau à gradient de microstructure. Un modèle basé sur la densité de dislocations tenant compte de l’influence du maclage et de la transformation de phase martensitique dans un acier TWIP/TRIP est proposé pour étudier l’influence des paramètres induits par SMAT. Ensuite, la densité de dislocations dans l’austénite et celle dans la martensite ainsi que les fractions volumiques de macles et de martensite au cours d’un impact sont évaluées numériquement avec un modèle d’éléments finis. Par ailleurs, afin d’étudier l’évolution de l’endommagement pendant le processus d’impact, l’endommagement a été introduit dans le modèle de la densité de dislocations. Enfin, un modèle visco-élastoplastique basé sur la densité de dislocations considérant l’effet de la taille de grain, le maclage et le taux de déformation a été proposé afin de mieux comprendre les effets du SMAT sur les propriétés mécaniques d’un acier TWIP/TRIP avec gradient de microstructure. Ainsi, pour étudier la réponse globale du matériau SMATé, la loi de mélange est utilisée en considérant le gradient du matériau comme une structure composée de différentes couches avec des microstructures et des propriétés mécaniques différentes.

Complete dehalogenation of florfenicol (FLO) was realized on a self-supporting, electrochromic WO3 nanocluster electrocatalyst prepared by anodization, effectively inhibiting the generation of toxic intermediates that can pose harmful influence on the ecosystem. Three dimensional, omnidirectional WO3 clusters made up of WO3 nanoflakes are grown from a W mesh substrate, which can work as catalyst and electrode enable the complete dehalogenation via a direct electron transfer because of the inherent electron-storage and self-supporting nature. Assisted by bias potential, continuous electron streams are generated and reserved in the porous WO3 interface, building an electron-rich circumstance for activating the C–Cl and C–F bonds to detach the halogen groups. The best electrocatalytic dehalogenation performance, 99.7% in 120 min was acquired using the optimal WO3/W anodized at 25 V. The possible sites attacked by electrons is predicted by Fukui index, that is evidenced by the MS of intermediates originated from FLO decomposition. ECOSAR simulation and E. coli surviving evaluation verifies that there is no hazard on ecosystem of the chemicals without –F and –Cl. Particularly, the self-supporting WO3 nanocluster electrocatalyst exhibits a superior durability with no decay in activity after 20 h running, indicating a promising prospect in establishing a feasible, cost-effective, and durable electrochemical strategy for antibiotic dehalogenation.

International audience; Introduction/Purpose Surface Mechanical Attrition Treatment (SMAT) is a mechanical surface treatment process that generates higher level of compressive residual stress coupled with stronger plastic deformation in the near surface region of structures than conventional shot peening. SMAT is based on multidirectional mechanical impacts between balls and the surface of material. The particularity of this technique lies in the fact that it can transform the top surface layer of material from coarse grains to nano-sized grains due to severe plastic slips. The over-treatment during surface mechanical treatments such as shot peening can generate damage in the near surface region. A good understanding of deformation mechanisms of material during SMAT, including damage, is important in terms of material processing optimization. Methods In this work, the damage evolution during impact loading is numerically investigated. For this purpose, a dislocation density-based viscoplastic constitutive model coupled with damage is proposed. The mechanical behavior of twinning induced plasticity (TWIP) and transformation induced plasticity (TRIP) steels is described by a dislocation density-based viscoplastic model including the kinetics of twinning and phase transformation of martensite, which allows to investigate the strain hardening behavior the materials. To predict the damage evolution of these ductile steels, the Gurson–Tvergaard–Needleman (GTN) yield criterion is combined with the dislocation density-based constitutive model. Results A user-defined subroutine is developed to implement these models and to obtain predicitive results that are in good agreement with experimental observations. Conclusions 3D numerical simulations of single impacts are performed to investigate the impacting process as well as the damage evolution due to high strain rate impacts.

International audience; Surface Mechanical Attrition Treatment (SMAT) is a surface treatment based on ball impact boosted by an ultrasonic generator. This technology is able to generate a gradient microstructure in the near surface region of a structure. In this region, the microstructure varies from ultrafine grains at the top treated surface to grains with a micrometric size in the central region. This difference in grain size consequently leads to the presence of a gradient mechanical properties in the SMAT affected region of the structure. Methods: In this work, a dislocation density-based model is developed to describe the gradient properties of a 316L steel treated by SMAT. For this purpose, some variables are introduced to take into account the gradient features of the microstructure including grain size, twinning and martensite transformation. To identify the parameters of the model, micro-pillar compression technique is used to investigate local mechanical properties of a cylindrical structure at different depth from the treated surface. These mechanical tests with micro-pillars, even though of compression nature, could provide qualitative information about the gradient mechanical features of the material. Results: The developed model is then implemented in a subroutine of ABAQUS Explicit to perform 3D simulations of tensile tests in order to investigate the properties of a gradient cylindrical structure. The obtained global mechanical behavior is in good agreement with the stress-strain curve obtained by experimental tensile tests in terms of strength and work hardening. At the local scale, various information can be obtained like the stress and the strain fields of the simulated structure. Conclusions: It has been found that the strain-induced twining and martensite transformation, the grain size and the thickness of the ultrafine grained layer all contribute to the global behaviour of the structure presenting a gradient microstructure generated by SMAT.

International audience; Surface Mechanical Attrition Treatment (SMAT) is a mechanical surface treatment process that generates higher level of compressive residual stress coupled with stronger plastic deformation in the near surface region of structures than conventional shot peening. SMAT is based on multidirectional mechanical impacts between balls and the surface of material. The particularity of this technique lies in the fact that it can transform the top surface layer of material from coarse grains to nano-sized grains due to severe plastic slips. The over-treatment during surface mechanical treatments such as shot peening can generate damage in the near surface region. A good understanding of deformation mechanisms of material during SMAT, including damage, is important in terms of material processing optimization.

Colloque avec actes et comité de lecture. Internationale.; International audience; Surface Mechanical Attrition Treatment (SMAT) is a process, which transforms the top surface layer of materials from coarse grains to nano-sized grains by severe plastic deformation. SMAT is based on multidirectional mechanical impacts between shot and the surface of material. As the strain rate is high and the accumulated plastic strain is large, a great number of defects such as dislocations and deformation twins can be generated at the top surface, which progressively lead to the formation of a nanostructured layer. Simultaneously, high compressive residual stresses may be introduced in the SMAT affected layer. This nanostructured layer coupled with compressive residual stresses induced by SMAT allow to significantly improve the mechanical properties of materials. Due to excellent mechanical properties of SMATed materials, it is necessary and useful to investigate the SMAT process both experimentally and numerically in order to obtain a better understanding and a better control of the process. Experimental studies, extensively performed previously and recorded in the literature, have shown that the mechanical properties of SMATed materials are highly influenced by the microstructure such as grain size and work hardening. From a modeling perspective, it would be highly beneficial to establish accurate numerical models of SMAT in order to consider the influence of the different parameters of this process at the different scales. In this work, a crystal plasticity model introduced in finite element analysis, taking into account the microstructure, was used to investigate the plastic activity due to the impacts between shot and the surface of material. To do this, the shape-controllable 3D Voronoï geometries as well as meshes were first generated using Neper software. A phenomenological crystal plasticity model implemented through user-defined ABAQUS subroutines was used in this work to perform numerical simulations. A number of parameters are studied such as shot size, impact velocity, incident angle, etc. The influences of these different parameters on slip systems and stress fields were analyzed. The first results demonstrated the interests of numerical simulations for this specific process.

International audience; Surface Mechanical Attrition Treatment (SMAT) is able to transform the top surface layer of materials from coarse grains to nano-sized grains by severe plastic deformation. SMAT is based on multidirectional mechanical impacts between balls and the surface of material. In this work, a crystal plasticity model introduced in finite element analysis, which takes into account the microstructure, is used to investigate the plastic activities due to the impacts between balls and the surface of material. A phenomenological crystal plasticity model implemented through user-defined ABAQUS subroutines is used in this work to perform numerical simulations. A set of parameters are studied such as ball size, crystal orientation, impact velocity, incident angle. The influences of these different parameters on plastic slip activities are analyzed. The first results demonstrate the interests of such numerical simulations for this specific process.

By introducing the software radio architecture briefly, we present a novel scheme of IF digitalization based on the software radio architecture, used in a direct sequence spread spectrum communication receiver, and its more detailed mathematical analysis, in order for improving the extent of digitalization, software, modularization in the available spread spectrum communication system.