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Tracking shear mode dynamics across the glass transition in a two-dimensional colloidal system
No full textLong-wavelength collective shear dynamics are profoundly different in solids and liquids. According to the theoretical framework developed by Maxwell and Frenkel, collective shear waves vanish upon melting by acquiring a characteristic wave-vector gap, known as the k gap. While this prediction has been supported by numerous simulations, experimental validation remains limited. Moreover, this phenomenon has never beentested across a continuous glass transition between a liquid phase and a glassy state with large but finite viscosity. In this work, we track the dispersion relation of collective shear modes in a two-dimensional colloidal system and provide direct experimental evidence for the emergence of a k gap. This gap opens continuously at an effective temperature consistent with the onset of the glass transition and the vanishing of the static shear modulus. By extracting the instantaneous shear velocity from the experimental data, we uncover a shear relaxation time exhibiting a super-Arrhenius temperature dependence characteristic of glass-forming materials, accurately described by the Vogel-Fulcher-Tammann relation. Our results confirm the predictions of the Maxwell-Frenkel framework and highlight their relevance across continuous melting processes originating from low-temperature amorphous solid phases
Surrogate modeling of the combined full-wave code TORIC and Fokker–Planck solver SSFPQL for ICRH minority heating at ASDEX Upgrade
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Synergizing ROS-biocatalysis and biofilm penetration via photothermal artificial enzymes with atomic homojunction sites to eradicate drug-resistant bacterial infections
No full textThe treatment of biofilm-associated drug-resistant bacterial infections remains a formidable clinical challenge, primarily due to the limited permeability of therapeutic agents through the dense extracellular matrix and the inherent drug resistance of biofilm-embedded microorganisms. Here, to overcome this challenge, we report the design of an atomic Fe-O-Mo/Fe-S-Mo homojunction photothermal nanosheet (Fe-HJPS) to synergize reactive oxygen species (ROS)-biocatalysis and biofilm penetration for eradicating drug-resistant bacterial infections. Spectroscopic and computational analyses reveal that the homojunction sites in the Fe-HJPS, comprising asymmetric Fe-S-Mo/Fe-O-Mo coordinations around Fe centers, downshift the high d-p hybrid orbital energy level compared to the original symmetric Fe-S-Mo coordination. This optimization enhances the adsorption affinity of oxygen intermediates and improves ROS-biocatalytic activities. Notably, under near-infrared (NIR) irradiation, the Fe-HJPS generates localized heat and disturbs the extracellular polymeric substances (EPS) in biofilms to increase the permeability of bacterial membranes, thereby facilitating ROS influx into bacterial cells. This dual-action mechanism of ROS production and biofilm penetration enables effective biofilm eradication at ultralow concentration (40 μg·mL−1), demonstrating superior efficacy against drug-resistant infections in both in vitro and in vivo models. Our findings establish atomic-scale homojunction in photothermal artificial enzymes as a versatile strategy for designing non-antibiotic antimicrobial nanomaterials that overcome drug-resistant bacterial infections. © 2025 Elsevier Ltd
Towards a minimum reporting standard to promote animal welfare and data quality in biologging research
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Artificial symbiosis for bulk production of bacterial cellulose composites
No full textSymbiotic relationships between micro-organisms are key to the function of all global ecosystems. Here we extrapolate this concept for biomaterial fabrication by creating artificial symbiotic relationships between species that are usually not grown synergistically in nature. Specifically, we combine the cellulose-producing bacterium Komagataeibacter hansenii and the green microalga Chlamydomonas reinhardtii to obtain bulk growth of bacterial cellulose. Usually, bacterial cellulose is produced as floating pellicles at the air-liquid interface of the growing media, because free oxygen, together with the nutrients in the culture medium, is required for the bacteria to synthesize the cellulose fibers. In the co-culture, bacterial cellulose production can be achieved in bulk beyond the spatial restriction of the air-liquid interface as the motile microalgae with photosynthetic activities act as oxygen-generating sites within the culture medium. In exchange, the highly porous and mechanically robust scaffold provided by the cellulose allows the algal-bacterial community to form a bio-composite up to several centimeters in thickness. We demonstrate that this symbiotic growth platform allows the simultaneous production of bulk bacterial cellulose in static incubation conditions, taking up an arbitrary and yet tunable 3D shape, dependent on the geometry of the culture vessel
