Mrs Bulletin最新文献

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.

Graphical abstract

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.

Graphical abstract

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.

Graphical abstract

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.