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Electrocatalytic upcycling of polyethylene terephthalate to formic acid and hydrogen fuels using CoCuO /MXene catalyst
No full textInternational audienceA promising way to address environmental problems caused by plastic waste is through its upcycling into renewable energy and resources. With annual production reaching millions of tons, one of the most widely single-use daily plastics, polyethylene terephthalate (PET), has recently been investigated in terms of chemical recycling to reduce its environmental impact and generate renewable fuels. This study introduces an innovative electrochemical method for the specific conversion of PET hydrolysate into high-value compounds utilizing CoCuOx@MXene/NF catalyst. Our findings revealed that the electrocatalyst was capable of facilitating the conversion of water into hydrogen (H2), while simultaneously oxidizing ethylene glycol (EG), obtained from PET plastic waste hydrolysis, into formate with a high selectivity and lower initial potential compared to water oxidation. Notably, the exceptional performance was attributed to the synergistic interfacial electronic coupling effect between CoCuOx and MXene, which results in a low overpotential (1.24 V@10 mA cm−2) and a high yield of formate product (87.6%). In addition, the electrolyzer could be operated using solar energy panel for upcycling of PET to formic acid and hydrogen fuels by using CoCuOx@MXene catalyst
Engaging Students in Spectroscopic Analysis of Organic Compounds: A Collaborative Tournament Approach for Third-Year Chemistry Students in Northern France
No full textInternational audienceThe ability to elucidate the structure of organic compounds from their nuclear magnetic resonance (NMR), infrared (IR), and mass spectrometry (MS) spectra is an essential skill, particularly for those engaged in the fields of synthetic and analytical organic chemistry. Spectral analysis constitutes a fundamental component of the curriculum for all chemistry students, as it requires the development of critical thinking skills. To engage and motivate students in the structure’s elucidation course, a gamified learning activity was designed in the form of a tournament involving third-year chemistry students from three universities in Northern France. In this tournament, the students are divided into teams comprising of four to five individuals. They are tasked with elucidating the structures of organic compounds based on their NMR, IR, and MS spectra in the shortest possible time with the fewest possible incorrect answers. The tournament was conducted in two distinct phases, each with a duration of 1.5 h and 1 h, respectively. The initial phase is competitive and involves teams of students from the same university, while the subsequent phase is designed to facilitate interaction and comparison between students from different universities, allowing them to discuss and evaluate their respective knowledge and methodology. The students were invited to evaluate the tournament approach by a questionnaire. The students expressed appreciation for the tournament and recommended its repetition in future years, citing its value in advancing their spectroscopy skills. Additionally, the students found the opportunity to interact with students from other universities and engage in discussions about their training programs and methodologies to be a valuable experience
identifications des peptides à courtes chaînes en agroalimentaire : challenges et aperçus critiques
No full textInternational audienceAs the global population continues to grow, optimizing the use of the protein resources produced by our planet has become essential for supporting the nutrition and health of both humans and animals. Over the years, the agro-food industry has played a key role in valorizing protein-rich by-products generated during food processing. Fermentation and enzymatic hydrolysis of these by-products are efficient, industry-friendly, and cost-effective methods for recovering peptides in the form of peptide hydrolysates. These hydrolysates contain a range of protein compounds, including large-, medium-, and short-chain peptides (SCPs), as well as amino acids, many of which are bioactive. Numerous databases now catalog food-derived bioactive peptides, with the BioPep-UWM database being one of the most comprehensive, containing 5,014 bioactive peptides (as of July 2024) associated with 90 distinct bioactivities. Of these, nearly 45% are SCPs, including 581 di-, 754 tri-, 385 tetra-, and 511 penta-peptides, totaling 2,231 SCPs. Despite their prevalence, the identification of SCPs remains more challenging than that of large- or medium-chain peptides, and research dedicated to SCP identification began only about twelve years ago. This review critically examines the technical challenges involved in SCP identification, offering a detailed timeline of approximately fifty key studies that have contributed to advancing the field. Specifically, the review explores enrichment and clean-up protocols, analytical methods, mass spectrometry techniques, and the bioinformatics approaches used for tandem mass spectrometry data processing in the context of SCP identification.Alors que la population mondiale continue de croître, l'optimisation de l'utilisation des ressources protéiques produites par notre planète est devenue essentielle pour soutenir la nutrition et la santé des humains et des animaux. Au fil des ans, l'industrie agroalimentaire a joué un rôle clé dans la valorisation des sous-produits riches en protéines générés lors de la transformation des aliments. La fermentation et l'hydrolyse enzymatique de ces sous-produits sont des méthodes efficaces, respectueuses de l'industrie et rentables pour récupérer les peptides sous forme d'hydrolysats de peptides. Ces hydrolysats contiennent une gamme de composés protéiques, y compris des peptides à chaîne large, moyenne et courte (SCP), ainsi que des acides aminés, dont beaucoup sont bioactifs. De nombreuses bases de données répertorient désormais les peptides bioactifs d'origine alimentaire, la base de données BioPep-UWM étant l'une des plus complètes, contenant 5 014 peptides bioactifs (en juillet 2024) associés à 90 bioactivités distinctes. Parmi ceux-ci, près de 45 % sont des SCP, dont 581 di-, 754 tri-, 385 tétra- et 511 penta-peptides, soit un total de 2 231 SCP. Malgré leur prévalence, l'identification des SCP reste plus difficile que celle des peptides à chaîne large ou moyenne, et la recherche consacrée à l'identification des SCP n'a commencé qu'il y a une douzaine d'années. Cette étude examine de manière critique les défis techniques liés à l'identification des SCP et propose une chronologie détaillée d'une cinquantaine d'études clés qui ont contribué à faire avancer le domaine. Plus précisément, l'étude explore les protocoles d'enrichissement et de nettoyage, les méthodes analytiques, les techniques de spectrométrie de masse et les approches bioinformatiques utilisées pour le traitement des données de spectrométrie de masse en tandem dans le contexte de l'identification des SCP
Applications of rhamnolipid surfactants in agriculture
No full textInternational audienceRhamnolipids are glycolipid biosurfactants naturally produced by Pseudomonas and Burkholderia bacteria, wellknown for their surface-active properties and eco-friendly advantages. Indeed, these compounds efficiently reduce the surface and interface tensions, possess potent biological activities against pathogens, and display low toxicity. Rhamnolipids thus hold significant promise for various industrial applications, including agriculture, which is in need of a transition to greener and more sustainable practices by reducing synthetic inputs. This review describes the knowledge about the antimicrobial properties of rhamnolipids against different phytopathogens, mainly fungal species, as well as their ability to trigger plant defense mechanisms and phytoprotection efficacy in different species. The recent literature investigating rhamnolipids as potential plant biostimulation agents, thanks to their abilities to improve soil health and plant tolerance to abiotic stresses, is also addressed. Finally, the prospect of rhamnolipids as a biopesticide and their overall contribution to sustainable agricultural practices is discussed
Conception de réacteurs discontinus à l'échelle du laboratoire pour la digestion anaérobie en milieu solide : comparaison pratique entre les digesteurs imprimés en 3D et les méthodes conventionnelles
No full textInternational audienceSolid-state anaerobic digestion (SS-AD) is a promising technology for treating organic waste and producing renewable energy. This study explores the feasibility of using 3D printing to rapidly design cost-effective laboratory-scale digesters for optimization experiments. Batch reactors were designed using fused deposition modeling (FDM) with polylactic acid (PLA) and stereolithography (SLA) with High Temp V2 resin. PLA had a negligible impact on methane yields, while raw SLA resin positively influenced methanogenic potential, likely due to residual isopropanol used in post-processing, causing a 19% increase in CH4 yield. The performance of the 3D-printed reactors was compared to that of a conventionally machined PMMA reactor using cattle manure as a substrate, showing comparable methane yields and process stability. Three-dimensional printing technologies have demonstrated remarkable efficiency in designing laboratory-scale digesters, with a 70% cost reduction for SLA technology and an 80% reduction in design time compared to conventional reactors designed by plastics processing, while maintaining comparable biogas production. FDM technologies with PLA have shown that they are not suitable for these uses. This study demonstrates the potential of additive manufacturing to accelerate SS-AD research and development. However, care must be taken in material selection and post-processing to avoid introducing experimental bias.La digestion anaérobie à l'état solide (SS-AD) est une technologie prometteuse pour le traitement des déchets organiques et la production d'énergie renouvelable. Cette étude explore la faisabilité de l'utilisation de l'impression 3D pour concevoir rapidement des digesteurs rentables à l'échelle du laboratoire pour des expériences d'optimisation. Des réacteurs discontinus ont été conçus à l'aide de la technologie FDM avec de l'acide polylactique (PLA) et de la stéréolithographie (SLA) avec la résine High Temp V2. Le PLA a eu un impact négligeable sur les rendements en méthane, tandis que la résine SLA brute a influencé positivement le potentiel méthanogène, probablement en raison de l'isopropanol résiduel utilisé dans le post-traitement, entraînant une augmentation de 19 % du rendement en CH4. Les performances des réacteurs imprimés en 3D ont été comparées à celles d'un réacteur en PMMA usiné de manière conventionnelle, utilisant du fumier de bovins comme substrat, et ont montré des rendements en méthane et une stabilité du processus comparables. Les technologies d'impression tridimensionnelle ont fait preuve d'une efficacité remarquable dans la conception de digesteurs à l'échelle du laboratoire, avec une réduction de 70 % des coûts pour la technologie SLA et une réduction de 80 % du temps de conception par rapport aux réacteurs conventionnels conçus par transformation des matières plastiques, tout en maintenant une production de biogaz comparable. Les technologies FDM avec PLA ont montré qu'elles n'étaient pas adaptées à ces utilisations. Cette étude démontre le potentiel de la fabrication additive pour accélérer la recherche et le développement en matière de SS-AD. Toutefois, il convient d'être prudent dans la sélection des matériaux et le post-traitement afin d'éviter d'introduire un biais expérimental
Fractures nationales : Retrait des services publics et dynamiques électorales
No full textInternational audienceL’objectif de cette étude est d’identifier les effets du retrait des équipements publics 1998-2018 sur les résultats des élections 2002-2022 en France. Différentes catégories de services publics sont définies, en fonction de la priorité accordée au bien-être de la population locale. Nous montrons ainsi que le retrait des services publics entraîne des votes populistes, à la fois à l’extrême gauche et à l’extrême droite, en particulier dans les communes les plus grandes. Les gains des partis d’extrême-gauche et d’extrême-droite se font en outre au détriment des partis traditionnels
Determination of the Critical Micelle Concentration of Gelatin, ι-Carrageenan, Pectin, Gellan Gum and Xanthan Gum by Mid Infrared Spectroscopy Among Other Techniques
No full textInternational audienceCritical micelle concentration (CMC) is the main physico-chemical parameter to be determined for surfactants due to its impact on surface activity and self-assembled aggregation. The aim of the present study is to determine CMC at 40 °C of gelatin, ι-carrageenan, pectin, gellan gum and xanthan gum by using different analytical techniques, particularly mid-infrared (MIR) spectroscopy as a rapid technique. The CMC values obtained for each hydrocolloid were relatively identical regardless of the applied technique: rheometer, conductimetry and automatic drop tensiometer (tracker). Indeed, CMC values of 55.16 g/L, 14 g/L, 6.04 g/L, 7 g/L and 3.48 g/L were obtained, respectively, for gelatin, ι-carrageenan, pectin, gellan gum and xanthan gum by using the surface tension method (tracker). Similar results were obtained for MIR spectroscopy since CMC values of 70 g/L, 15 g/L, 7 g/L, 5 g/L and 6 g/L were observed, respectively, for gelatin, ι-carrageenan, pectin, gellan gum and xanthan gum. The results presented here clearly demonstrate that it is possible to use MIR spectroscopy as a rapid analytical technique for the CMC determination of the investigated hydrocolloids
pH-dependent emulsifying properties of pea protein isolate: Investigation of the structure – Function relationship
No full textInternational audienceThis study investigated the relationship between pea protein isolates (PPI) emulsifying properties and theirstructural, interfacial, and physicochemical characteristics at various pH values (native pH, 7, 5, and 3).Emulsion characteristics including emulsifying activity and stability, droplet size, flocculation index (FI) andcoalescence index (CI) were examined. Additionally, physicochemical properties such as solubility, zeta potential,surface hydrophobicity, interfacial protein adsorption and protein conformation were analyzed. Resultsrevealed significant pH-dependent variations in emulsifying performance. The poorest emulsifying performancewas observed at pH 5, with the largest droplet size (28.84 μm) and highest CI (38.94 %). Optimal emulsifyingproperties were noticed at native pH, with the smallest droplet size (7.73 μm) and lowest CI (4.69). At pH 3, goodemulsifying ability with the highest physical stability (5.43) were observed, associated with increased surfacehydrophobicity and the presence of some aggregates contributing to the formation of cohesive interfacial film.Structural elements, particularly β-sheets and random coils, were positively correlated with emulsifying activityand stability, while β-turns had a negative impact. These findings provide insights into the pH-dependentemulsifying behavior of PPI, highlighting the complex relationship between protein structure and functionality,enabling the optimization of the use of PPI as an emulsifier in food applications
Instrumentation and Characterisation of Mixed GO Electrical Steel Magnetic Cores
No full textInternational audienceThis paper investigates the performance implications of mixing grain-oriented electrical steel (GOES) grades in a single-phase transformer core through comprehensive characterization and instrumentation. An extensive measurement setup using B-coils and H-coils enables detailed mapping of local magnetic flux density and field strength distributions. Experimental results demonstratethat strategic grade mixing can enhance core performance, with improvements dependent on the magnetic property differences between selected grades. The findings provide insights into local magnetic behavior within mixed-grade cores, contributing to the optimization of power transformer design
Phenolic compounds fingerprints show distinct ligninolytic bacteria behaviours during technical lignins conversion
No full textInternational audienceLignins, one of the main components of plant cell wall, and by-products of certain industries (paper and wood industries,…) are a renewable source of aromatic molecules. They can be degraded and transformed by microbial and enzymatic processes known to be respectful of the environment. Biological valorization of lignins remains challenging as biocatalysts are not sufficiently effective and efficient. Moreover, the chemical complexity and heterogeneity of lignins are a barrier to their use. Understanding the microbial behaviour on lignins by fingerprinting their efficient transformation could lead to the development of effective biological routes to valorise these aromatic polymers. Ligninolytic bacteria present some interesting features in term of ligninolytic enzymes productions, utilization of aromatic compounds via various intracellular pathways and the productions of molecules of interest from aromatic molecules. In this work, multiple approaches (growth studies, ligninolytic activities production, lignin modifications and phenolic compounds fingerprints) were used to understand the behaviour of two ligninolytic bacteria Pandoraea norimbergensis and Comamonas composti, in presence of lignins with different structures and origins. Results showed dissimilar growths profiles, lignin modifications, consumption and production of phenolic monomers and oligomers according to the bacteria and the lignin used. To achieve efficient transformation of lignins, suitable combination of biocatalysts and lignins is required and the microorganisms used must be selected on the basis of their metabolic capacity, and the structure and composition of lignin