Characterization of Conus textile predatory venom by capillary electrophoresis hyphenated to mass spectrometry

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Capability of thermodesorption/pyrolysis DART FT-ICR MS to distinguish fluoropolymers and identify blend composition

International audienceDirect analysis in real time (DART) was coupled with a thermal desorption/pyrolysis (TDPy) device for the analysis of fluoropolymers. The product ions were analyzed using a Fourier transform cyclotron resonance mass spectrometer (FT-ICR MS). Two different polyvinylidene fluoride (PVDF) samples were studied individually and in a 50/50 mixture. This study demonstrates the capability of TDPy DART FT-ICR MS to provide information on PVDF polymers, including the determination of end-groups and the detection of comonomers.The temperature program used enabled the desorption of the smallest oligomers (Mn ≈ 600 Da) below 400 °C, allowing for the identification of the end-groups, which ensured the differentiation of the PVDF. At temperatures above 400 °C, Cw Hx Fy- ions were predominantly formed as a result of the thermal cleavage of the PVDF backbone.Specific pyrolysis products observed for one PVDF sample suggested the presence of 4.6 mol% hexafluoropropylene (HFP), as determined by NMR measurements. The molar percentage of HFP was also determined by a new approach using TDPy DART MS. The analysis of a 50/50 PVDF blend revealed species from both polymers during the thermo-desorption and pyrolysis events, confirming the ability of the proposed methodology to determine the mol% of the HFP comonomer. This represents the first TDPy DART FT-ICR MS study of fluoropolymers. Applicable to non-soluble or poorly soluble polymers, the proposed methodology enables the identification of end-groups, suggests the possibility of distinguishing fluoropolymers, and identifies blend composition. Additionally, the molar percentage of comonomers can be defined for poly(VDF-co-HFP) copolymers.</div

Proof of concept for manufacturing of composite tapes with household PolyEthylene Terephthalate (PET) as matrix

International audienceNew recycling method for PET is investigated by manufacturing thermoplastic tapes using recycled PolyEthylene Terephthalate (PET) as matrix. PET, which is widely used in the packaging industry, especially for bottles, remains a challenge due to the degradation of its properties during mechanical recycling. Faced with these challenges, a new recycling method for PET is investigated by manufacturing recycled and recyclable thermoplastic tapes using recycled PET as matrix. The process is based on a dissolution-precipitation method inspired by the phase inversion membrane technique. A solubility theory have been used to identify the best solvent/non-solvent combinations.Experimental results show the efficiency of three solvents: Trifluoroacetic Acid (TFA) , Hexafluoroisopropanol (HFIP) and Gamma-Valerolacone (GVL) combined with water and ethanol as non-solvent and evaporation to dissolve and precipitate PET in the fibrous reinforcement to create the thermoplastic tape. Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analyses show that the chemical structure of PET has been preserved. SEM images reveal the influence of the choice of solvent/non-solvent combination on porosity and pore distribution in the material.Proof-of-concept studies carried out with TFA and HFIP suggest that the HFIP/ethanol combination is the most suitable for minimizing degradation and maximizing the matrix content in the fibrous reinforcement. This work therefore lays the foundations for the development of this new recycling method as part of a move towards a circular economy and a reduction in the impact of composite materials, which are difficult to recycle

Photophysics of cu-loaded MIL-125(Ti)-NH₂: Unravelling the role of cu oxidation states through time-resolved spectroscopy and density functional theory

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Benzoxaborole drugs in therapy: successful cases of Tavaborole and Crisaborole

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Culturable macroplastic-associated potential human pathogens in coral reef lagoons, Madagascar

Potentially human pathogenic bacteria (PHPBs) have been detected in plastic-associated marine microbiomes, primarily through DNA-based methods. However, data on their culturability and concentrations on plastics remain limited, yet are essential to assess actual health risks. To address this gap, 70 floating macroplastic and 20 seawater samples were collected from two human-impacted reef lagoons in southwestern Madagascar (Atsimo-Andrefana region). PHPBs were cultured from their microbiomes using selective media and quantified. Macroplastics were predominantly polypropylene (34 %) and polyamide (31 %). In increasing order of concentration, four culturable PHPBs, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, and Vibrio Harveyi clade species, were identified on both macroplastics and in seawater, across all sites and polymer types. Notably, 52 % of macroplastic samples harbored two PHPB species simultaneously, while only 7 % were PHPB-free. Concentrations of all PHPBs were consistently and significantly higher on macroplastics than in seawater, regardless of the measurement unit or polymer type, with the Vibrio Harveyi clade being the most abundant. No significant correlations were observed among PHPB species concentrations, suggesting limited interaction and independent colonization. These findings indicate that floating macroplastics may serve as reservoirs and fomites for viable PHPBs. However, their potential impacts on ecosystems and human health should be interpreted cautiously. We emphasize the need to contextualize PHPB concentration data by considering factors such as exposure pathways, environmental persistence, and bacterial virulence, rather than relying solely on concentration-based comparisons, which may lead to misinterpretation

Balancing power output and efficiency in thermophotovoltaics through spectral shaping of selective emitters

International audienceThermophotovoltaic (TPV) systems propose a promising method of converting heat into electricity, with the thermal emitter playing a pivotal role. However, optimizing its emission spectrum poses a significant challenge, with sub-bandgap losses and thermalization from high-energy photon absorption contributing to this complexity. Although the absorption of high-energy photons is beneficial for increasing the system’s power output by providing additional energy, it simultaneously diminishes the system’s efficiency. This study addresses these challenges by exploring the optimization of the emission spectrum of selective thermal emitters in TPV systems. Our objective is to reach a balance between maximizing electrical power output, which favors a broadband spectrum, and maximizing efficiency, which requires a narrowband spectrum. To achieve this, numerical optimization methods are coupled with the Shockley-Queisser limit to find an optimal compromise between these opposing criteria. Ultimately, this optimization endeavor aims to enhance the overall performance of TPV systems. Here, we present the results of calculations predicting the spectral shapes of ideal selective emitters for TPVsystems with emitter temperatures ranging from 300◦C to 2000◦C and photovoltaic cell bandgap energies from 0.17 eV to 1.1 eV. For a configuration with an emitter at 900◦C coupled to a 0.25 eV bandgap cell under the assumption of perfect coupling (view factor of 1), the ideal emission spectrum was found to have emissivity of unity between 0.25 eV and 0.62 eV and zero elsewhere. Accounting for this ideal emission spectrum, the results show an efficiency of 41.5% and an output power density of 2.59 W∕cm2

Phi-FEM-FNO: a new approach to train a Neural Operator as a fast PDE solver for variable geometries

International audienceIn this paper, we propose a way to solve partial differential equations (PDEs) by combining machine learning techniques and the finite element method called phi-FEM. For that, we use the Fourier Neural Operator (FNO), a learning mapping operator. The purpose of this paper is to provide numerical evidence to show the effectiveness of this technique. We will focus here on the resolution of two equations: the Poisson-Dirichlet equation and the non-linear elasticity equations. The key idea of our method is to address the challenging scenario of varying domains, where each problem is solved on a different geometry. The considered domains are defined by level-set functions due to the use of the phi-FEM approach. We will first recall the idea of $\varphi$-FEM and of the Fourier Neural Operator. Then, we will explain how to combine these two methods. We will finally illustrate the efficiency of this combination with some numerical results on three test cases. In addition, in the last test case, we propose a new numerical scheme for hyperelastic materials following the phi-FEM paradigm

Discrete numerical analysis of cohesive granular flow in a thin rotating drum: Flow regimes and cohesion estimation

International audienceIn this study, we investigate the rheological behavior of cohesive granular flows within a rotating drum geometry using discrete element method (DEM) simulations. By systematically varying particle size, cohesion, and stiffness, we identify the emergence of distinct flow regimes-consistent with prior experimental observations. While the transitions between these regimes are primarily governed by cohesion, particle stiffness is also shown to significantly influence flow dynamics.To interpret the numerical results, we employ a dimensional analysis rooted in the physics of adhesive particle collisions. This analysis provides a conceptual framework for the remainder of the paper, which explores how "upscaled" discrete simulations can replicate experimental findings and help infer interparticle contact properties such as the adhesive surface energy. Notably, we use it to examine rotating drum experiments involving a unique class of granular materials, ice powders, which holds particular relevance in planetary science applications, and which flowability was shown to be strongly temperature-dependent.</div