Mrs Bulletin最新文献

Metal-halide perovskites (MHPs) with unique electronic and optical properties have emerged as promising materials with a broad spectrum of applications in photovoltaics, optoelectronic, and photonic devices. The distinct properties and tremendous potential of MHPs are intricately defined by excitons and collective quantum states. This article reviews the excitonic states and coordinated interplay of charge, spin, and lattice. We discuss the recent experimental and theoretical discoveries of excitonic phenomena, as well as correlated states involving condensation and cooperative emission. Additionally, our exploration extends to the structural properties of MHPs that facilitate the emergence of robust quantum states, even at room temperatures. Finally, an overview of the remaining challenges and potential applications of MHPs in quantum optics, coherent light sources, electrically driven amplified spontaneous emission, and superfluorescent lasing is provided.

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Abstract

Mycelium is crucial in decomposing biomass and cycling nutrients in nature. While various environmental factors can influence mycelium growth, the role of substrate mechanics is not yet clear. In this study, we investigate the effect of substrate stiffness on mycelium growth. We prepared agar substrates of different concentrations to grow the mycelium, but kept other environmental and chemical conditions consistent. We made a time-lapse recording of the growing history with minimum interruption. We repeated our tests for different species. Our results generally support that mycelium grows faster on a stiffer substrate, Ganoderma lucidum gives the highest growth rate and Pleurotus eryngii is most sensitive to substrate stiffness. We combined experimental characterization and computational simulation to investigate the mechanism and discovered that mycelium concentrates on the surface of a rigid substrate, but penetrates the soft one. Our Monte Carlo simulations illustrate that such a penetration allows mycelium to grow in the three-dimensional space, but effectively slows down the surface occupation speed. Our study provides insights into fungal growth and reveals that the mycelium growth rate can be tuned through substrate stiffness, thus reducing the time for producing mycelium-based composites.

Impact statement

We used agar substrates and tuned its stiffness to culture mycelium and compared tune its stiffness to culture mycelium and compare its growth in a well-controlled condition. Our results revealed that mycelium grows faster on stiffer substrates, thus fully occupying the petri dish surface more quickly. We repeated our study several times by testing four species, P. eryngii, G. lucidum, Trametes versicolor, and Flammulina velutipes, and the stiffest substrate always gives the highest mean growing rate than others. The G. lucidum shows the highest spreading rate that is obtained on the stiffest substrate as 39.1 ± 2.0 mm²/h. We found that the mycelium on a soft substrate will grow into the substrate instead of spreading on the stiffer surface. Our Monte Carlo simulations further show that once the fibers grow into a three-dimensional substrate, its growth is slower than growing on a two-dimensional surface, providing a microscopic mechanism of the substrate stiffness effect. This study’s analysis of how substrate stiffness impacts mycelium growth is new, bridging a critical knowledge gap in understanding the relationship between substrate mechanics and fungal ecology. The knowledge from this study has a potential in accelerating sustainable manufacturing of mycelium-based composite by adjusting substrate mechanics.

Graphical Abstract

Excitons in a semiconductor are Coulomb interaction-bound pairs of excited electrons in the conduction band and holes in the valence band, which can either be free bosonic particles with well-defined integer spins, called the free excitons or bound at defect/impurity sites, called bound excitons. Theory predicts several fascinating collective phenomena emanating from excitons, such as Bose–Einstein condensation, high-temperature superconductivity, and strongly correlated excitonic insulator states. There are also proposals to utilize excitons for transferring and processing information. This new paradigm of electronics is expected to be more energy efficient and compatible with optical communication. However, exciton binding energy is an important factor to be considered in realizing the excitons at room temperature (RT). In this respect, certain nitride and oxide semiconductors, such as GaN, InN, and AlN and ZnO, TiO₂, and Cu₂O, are especially interesting as the excitonic binding energy in these materials is sufficiently high, which facilitates their survival above RT. By harnessing and controlling the excitonic behavior, researchers can engineer materials with specific functionalities, leading to innovations in materials science and device fabrication. Here, we review recent developments toward the understanding of excitons in certain nitride and oxide semiconductors as well as their heterostructures and nanostructures.

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Two-dimensional (2D) materials are attractive systems to explore exciton physics and possible applications in optoelectronics, opto-spintronics, and quantum technologies. Monolayer transition-metal dichalcogenides (TMDs) are direct gap 2D semiconductor materials with robust excitons and two inequivalent K⁺ and K⁻ valleys. They can be vertically stacked to form van der Waals (vdW) heterostructures with typically Type II band alignment that enables the formation of interlayer excitons (IEs) and creates Moiré patterns. Magnetic 2D materials are also promising systems to explore exciton physics and their correlations with magnetic properties. They can be stacked with TMD materials to form magnetic vdW heterostructures. Their optical properties are strongly dependent on the number of layers, charge transfer, defects, strain, and twist angle stacking, which offer a versatile platform to control their physical properties. Here, we review some recent discoveries on the exciton and valley properties of van der Waals materials and heterostructures.

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Abstract

Plant-based cheese alternatives often demonstrate poor melt, stretch, texture, and nutritional value. Dairy cheese has a complex structure of fats and caseins, which has proved challenging to replicate using plant ingredients. In this study, the functional characteristics of starch-structured plant-based cheeses were evaluated as a function of increasing protein contents up to 10% w/w, to determine if protein addition was beneficial to cheese functionality. Any addition of protein to the starch matrix increased melt, decreased oil loss, and increased hardness. Thermo-rheological and thermo-mechanical parameters of the cheeses were determined and correlated to the improved functionality. The relative decrease in the storage modulus (G′) from 40°C to 95°C was strongly correlated to the observed increase in melt. This study suggests that there is potential for the improvement in the functionality and performance of plant-based cheese alternatives by protein addition, while also enhancing their nutritional profile.

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Impact Statement

With changing environmental and sustainability demands, as well as dietary preferences, there is an opportunity to close the gap between dairy and plant-based cheeses. Based on the target cost, functionality, and nutritional value, the protein content of plant-based cheeses can be modified so that the functional, textural, and nutritional properties can meet consumer expectations. With an increased understanding of the broader textural properties of plant-based cheeses, we can better engineer the formulations for various food applications. Existing manufacturing equipment and processes can be used to improve sustainability, while the formulations can be altered to create a more desirable product. In this letter, we show that it should not be an expectation to settle for plant-based alternatives that underperform, as there is potential to greatly improve this sector.