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Leveraging mirror-image glycans in carbohydrate materials
No full textChirality has become a fundamental design principle to craft peptide materials. In contrast, the systematic exploitation of chirality to build glycan materials remains largely unexplored, despite the rich chiral diversity of carbohydrates, with both d- and l-configurations readily available in nature. Here, we emphasize the added value of exploring mirror-image glycans to tailor carbohydrate materials. By examining the distinctive chiral features of carbohydrates in comparison to peptides, we demonstrate how these characteristics provide powerful opportunities to modulate and elucidate the rules governing glycan assembly. We discuss examples of carbohydrate materials based on individual enantiomers, the co-assembly of racemic mixtures, and the assembly of heterochiral sequences. Each section is introduced with key insights from peptide materials, serving as inspiration and guidance for the future design of glycan assemblies
Micromagnetics of conical-helix textures in thin films with different kinds of Dzyaloshinskii-Moriya interactions
No full textChiral spin textures in ferromagnetic materials with Dzyaloshinskii-Moriya interactions (DMIs) have attracted significant interest in recent years owing to their potential applications in nanodevices. This work focuses on describing stable conical-helix configurations hosted in ultrathin films with DMI and perpendicular anisotropy. These states are studied for different kinds of DMIs, including symmetry classes T, Cnv, isotropic and anisotropic D2d, Dn, Cn, and S4. A parameterised analytical model of these configurations is proposed, enabling the determination of optimal parameters characterising the magnetic texture, such as the pitch vector or nucleation field. To substantiate the results, micromagnetic simulations are developed for comparison with the theoretical solutions. Numerical solutions are optimized by implementing finite-difference codes that use next-nearest neighbours and explicit Robin boundary conditions stemming from symmetric exchange and DMI. It is shown that these numerical enhancements decrease anisotropic effects in helical solutions. This study establishes a method to analyse conical-helix textures in thin-film systems with any DMI, which can be simulated with higher precision using the open-access codes developed here
Mechanical sensing of metamagnetic tricriticality in two-dimensional CrI<sub>3</sub>
No full textLayered Ising metamagnets are antiferromagnetic (AF) materials consisting of monolayer Ising ferromagnets coupled to each other via interlayer AF interactions. They exhibit rich magnetic phase diagrams, featuring tricritical and critical end points, due to the competing magnetic interactions and the Ising anisotropy. While conventional thermodynamic probes can identify these critical points in bulk Ising metamagnets, achieving this in the two-dimensional (2D) limit, where enhanced fluctuation effects can substantially modify critical phenomena, remains to be realized. Here, we combine specific heat capacity (CV) and magnetic circular dichroism measurements to identify these critical points, extract a tricritical exponent, and map out the complete magnetic phase diagram of 2D Ising metamagnetic CrI3. This is achieved in a nanomechanical device of 6-layer CrI3, in which a direct measurement of the temperature derivative of its mechanical resonance frequency gives CV). The tricritical point is identified by the onset of an abrupt spin-flip transition on one side and, on the other side, by a vanishing specific heat λ-anomaly for a continuous AF phase transition. In contrast, only the spin-flip transition remains near the critical end point. Our results establish nanomechanical calorimetry as a general route to classify metamagnetic phase transitions and to study multicritical phenomena in 2D magnets
Association of sexual dysfunctions according to DSM-5 criteria with structural brain differences in women and men from the Hamburg City Health Study
No full textEpigenetic aging in monozygotic twins exposed to psychosocial adversity suggests sex-specific, contextual outcomes
No full textTransitioning of the Chemical Industry Toward a Net-Zero Carbon Dioxide Emission Path
No full textEmissions from the chemical industry, both for energy and use of raw materials, account for approximately 6% of man-made greenhouse gas emissions. In order to keep global warming at acceptable levels, these emissions—as all other emissions—have to be drastically reduced. One way to do this is the elimination of fossil feedstock from chemical production and meeting the energy demand from renewable resources. This contribution shows that the essential elements are already available at scale to provide C1-building blocks, olefins, aromatics, and ammonia as the key base chemicals. Methanol can be produced from CO2 and renewable hydrogen, olefins from the methanol-to-olefins and related processes, for aromatics, the methanol-to-aromatics process is available, supplemented by biomass and recycled polymers as feedstock, and also for ammonia process concepts with a strongly reduced greenhouse gas footprint are available. Current hurdles are the partly unattractive economic boundary conditions and the rate at which a change in the feedstock situation can be achieved. Moreover, high amounts of renewable energy are required, which accounts for about half of the current global electricity production
Valorisation des découvertes archéologiques de la Falémé (Sénégal): résultats de la 27 ème année du programme «Peuplement humain et paléoenvironnement en Afrique»
No full text1. Introduction 2. Datation des sédiments par les méthodes de la luminescence stimulée optiquement (OSL) et de la résonance paramagnétique électronique (ESR) 2.1 Problématique de la datation des sédiments des sites ESA et MSA 2.2 Échantillons traités et premières estimations 2.3 Protocoles analytiques 2.4 Conclusion 3. Clôture de l’exploration du secteur archéologique du Ravin des Guêpiers/ Goundafa : diagnostic du matériel lithique découvert en 2023 3.1 Les sondages du Ravin des Guêpiers 3.1.1 Secteur V 3.1.2 Secteur VI 3.1.3 Secteur VII 3.1.4 Secteur VIII 3.1.5 Secteur IX 3.2 Goundafa II 3.2.1 Surface 3.2.2 La couche 5 3.2.3 La couche 4 : niveau archéologique no 1 3.2.4 La couche 3 : niveau archéologique no 2 3.2.5 La couche 2 : niveau archéologique no 3 3.2.6 La couche 1 3.3. Conclusion 4. Le site de Toumboura VI dans la vallée de la Falémé (Sénégal) : résultats préliminaires de la campagne de fouille 2023 4.1 Introduction 4.2 Méthode de fouille 4.3 Résultats 4.3.1 La chrono-stratigraphie 4.3.2 Analyse anthracologique 4.3.3 Le matériel archéologique 4.4 Discussion et conclusion 5. Reconstitution de la tradition sidérurgique FAL02 à partir des sites de Didé Ouest 1 et de Birandjikou : bilan archéologique et expérimental 5.1 Introduction 5.2 Définition de la tradition technique FAL02 5.2.1 Reconstitution des fourneaux 5.2.2 Organisation de la production 5.3 Questionnement sur le fonctionnement de la ventilation 5.3.1 Description du protocole expérimental 5.3.2 Résultats 5.3.3 Conclusions de l’expérimentation 5.4 Remarques conclusives 6. Céramiques protohistoriques de la vallée de la Falémé : étude des matériaux 6.1 Introduction 6.2 Résultats 6.2.1 Le groupe pétrographique 1 6.2.2 Le groupe pétrographique 2 6.2.3 Le groupe pétrographique 3 6.3 Discussion et conclusion 7. Synthèse et conclusio