Physics

Mechanoluminescence (ML) in semiconductors originates from the coupled interaction between mechanical stress, internal polarization fields, and trapped charge carriers. Rather than proposing a new mechanism, this perspective synthesizes and critically examines the existing theoretical and experimental studies that attribute stress-induced light emission to piezoelectrically assisted electron detrapping in semiconducting and phosphor materials. Emphasis is placed on frameworks developed for systems such as ZnS:Mn and ZnO, where mechanically generated piezoelectric potentials modulate trap depths, facilitate carrier release, and enable radiative recombination. By revisiting established formulations and extending their discussion to include non-uniform field distributions, multi-level trap states, and realistic defect landscapes, this perspective highlights how piezoelectric field effects can coexist with, complement, or dominate over thermal and triboelectric contributions depending on material chemistry, defect structure, temperature, and loading conditions. Comparative analysis underscores that piezoelectric assisted detrapping is particularly effective under dynamic stress and low-temperature regimes, while thermally activated processes remain robust and reliable in other contexts. Together, these insights provide a balanced interpretative framework for understanding ML across material classes and offer guiding principles for the rational design of self-powered mechanoluminescent and piezophotonic systems for stress sensing, structural health monitoring, and energy-autonomous optoelectronic applications and to identify key directions for future research.

Bound states in the continuum (BICs) are typically investigated in terms of distinct formation mechanisms, such as symmetry-protected (SP), Friedrich–Wintgen (FW), or Fabry–Pérot (FP) BICs. However, their coexistence and mutual interaction within a single plasmonic architecture have not been systematically examined so far. In this work, we show that these distinct BIC classes can coexist and interact in a metal–insulator–metal waveguide incorporating a double T-shaped cavity. Using an analytically tractable Green’s function formalism supported by full-wave finite element simulations, we identify the simultaneous emergence of twin FW-BICs and FP-BICs. Unlike FW-BICs, which are independent of the separation between the two cavities, FP-BICs occur at a discrete set of cavity separations. We show that the interaction between the two types of BICs gives rise to multi-BICs, featuring highly confined, non-radiative modes. We further analyze how breaking the BIC condition leads to Fano-like and plasmon-induced reflection resonances as well as the Dicke effect. The combined analytical–numerical analysis provides physical insight into BIC formation in plasmonic waveguides and underscores the potential of these nanostructures for sensing and integrated optical filtering applications.

Metal to insulator transition (MIT) is accompanied by huge changes in physical responses by the control and tuning of experimental parameters like doping, pressure, chemical composition, and magnetic field. Here, we study the magnetic field-driven MIT for two pnictides in their elemental form, namely, arsenic and bismuth. At low temperatures, bismuth shows an unusual behavior of a re-entrant insulator–metal transition (IMT) at high fields in addition to a higher temperature MIT at smaller fields. However, arsenic shows the commonly observed single MIT. Shubnikov–de Haas oscillations are observed for both As and Bi below 10 K. Giant magnetoresistance of the order of ∼105 [magnetoresistance (MR)%] is observed for both crystals at 2 K and the 14 T transverse magnetic field. The unusual Kohler scaling behavior of MR at low temperature indicates the presence of increased carrier density attributed to the melting of excitons. Based on a microscopic model, the microscopic processes underpinning the unusual features of a field-driven MIT and re-entrant IMT, along with the relevance of both excitonic and Bose metal correlations near these incipient instabilities, are qualitatively described in the framework of field-driven excitonic condensate and Das–Doniach preformed pair scenarios in one single picture.

Plasmonic nanostructures provide an effective route to enhance light–matter interaction in advanced photovoltaic architectures. This work reports a numerical analysis of localized surface plasmon resonance (LSPR), near-field electromagnetic enhancement, absorption efficiency, and the spectral tunability of the laser dye 7-amino-4 (trifluoromethyl) coumarin (C-151) when coupled with a graphene-coated nanomatryoshka architecture. The multilayer nanomatryoshka consists of a CdSe/Cu2O core, a TiN/HfN plasmonic shell, and a graphene outer layer. The optical characteristics are systematically examined as functions of semiconductor core radius, plasmonic shell thickness, and graphene chemical potential. The analysis demonstrates pronounced LSPR excitation accompanied by strong near-field electromagnetic enhancement and broadband absorption enhancement driven by plasmon–exciton interaction and graphene-enabled spectral tuning. Unlike conventional noble-metal plasmonic systems, nanomatryoshka structures based on TiN and HfN demonstrate superior thermal stability and spectral robustness while preserving strong plasmonic behavior. The resulting enhancement in optical absorption underscores the effectiveness of graphene-integrated refractory plasmonic nanostructures for efficient light harvesting and advanced photovoltaic and optoelectronic applications.

Advanced silicon solar cell technologies employ multilayer architectures and offer significant potential to improve power conversion efficiency. However, fabrication-induced nonidealities often lead to charge-transport issues and reduced photovoltaic performance. Therefore, a systematic assessment of the device is essential to pinpoint the specific regions of performance loss and to enable targeted optimization. This study applies detailed impedance spectroscopy (IS) with a broadband AC signal in the range of 1 Hz to 1 MHz for silicon heterojunction (SHJ) solar cells; one is defect-dominated charge transfer in a-Si:H layer, another one is hindered charge transport at the p-a-Si:H/ITO hole-selective contact, and an optimized SHJ cell. These effects manifest within a distinct frequency range of the IS response, thereby enabling the identification of the dominant charge-carrier resistive and recombination-loss mechanisms. A deeper analysis of the Nyquist plot, together with frequency-dispersed phase shifts and real and imaginary impedance responses (Z′, Z″), provides clear signatures of the specific location of the performance loss. It is observed that the optimized device has a well-established depletion region and minority-carrier diffusion, with negligible resistive drop across the device. However, in unoptimized devices, additional charge-delay and impedance features appear within a specific frequency range, revealing distinct origins of the performance loss: one associated with the i-a-Si:H layer and the other with the ITO contact. Therefore, IS provides a powerful basis for diagnosing distortions in photocurrent–voltage graphs, degradation pathways, and transport bottlenecks. The frequency-resolved IS can be a critical tool for guiding interface engineering and process optimization of any optoelectronic device.

Effective modulation of magnetic permeability plays a vital role in the development of high-performance inductors. Here, phase field simulations of hard/soft ferrite composites (BaM/NiZn) clarify how exchange coupling and microstructure impact magnetic permeability. We show that particle size, volume fraction, and orientation of the hard phase can effectively control the transition from collinear to non-collinear coupling, with a critical exchange size of rcr≈12nm. Increasing the hard-phase fraction deepens the anisotropy energy well and monotonically suppresses permeability. In contrast, rotating the BaM easy axis to 90° relative to the applied field produces a strong enhancement: at a 10 nm radius and η=0.1 volume fraction, the effective permeability could be more than 30 times larger than in the parallel configuration and then saturates for larger particles. This study establishes a microstructure–permeability-based physical framework for designing hard/soft magnetic composite systems.

The bacterial pangenome contains a vast diversity of antiphage systems, whose overall extent is still unknown. In this study, we developed complementary machine learning approaches to systematically predict antiphage function from genomic context, protein sequence, or their combination, achieving up to 99% precision and 92% recall. We validated these models experimentally in <i>Escherichia</i> and <i>Streptomyces</i> with the discovery of 12 antiphage systems. Applied to over 32,000 bacterial genomes, these models expand the predicted antiphage repertoire, with ~1.5% of bacterial genomes devoted to defense and more than 85% of predicted protein families remaining uncharacterized. We provide an interactive catalog of more than 19,000 candidate operon families for experimental follow-up. Together, these findings show that most molecular diversity in bacterial immunity remains uncharacterized and provide a foundation for its systematic exploration.

The victors of today's space race stand to have unprecedented power on Earth.

Conventional thermal propane dehydrogenation (PDH) faces several notable drawbacks, including high energy requirements, coking-induced catalyst deactivation, and the need for product separation. An electrocatalytic approach, using self-assembled ionic liquid (IL)-tin dioxide (SnO₂) hollow spheres as the electrocatalyst, enables efficient PDH at ambient temperature. In this process, bromopropane formed in the anolyte from propane reacts with hydroxyl anions from the cathode to yield propene. The propene selectivity exceeds 98%, and the continuous production of high-purity (>99%) propene gas from the anolyte eliminates the need for downstream separation. The IL-SnO₂ catalyst maintains its activity and selectivity for more than 6000 hours, with a small voltage increase rate of 3.16 microvolts per hour. Mechanistic studies suggest that the IL layer enhances propane adsorption and facilitates the carbon-hydrogen bond activation step on adjacent Sn sites. After reaction, the IL layer promotes propene desorption and suppresses deep dehydrogenation.

Growing use of p-tau217 raises concerns about testing in healthy people.

Antitumor immunity requires conventional type 1 dendritic cells (cDC1s). How cDC1s maintain functional fitness in the tumor microenvironment remains unclear. In this study, we established that intratumoral cDC1s exhibited discrete mitochondrial states and that OPA1-mediated mitochondrial energy and redox metabolism dictated cDC1 antitumor responses. Mechanistically, OPA1 orchestrated antigen presentation and the CD8⁺ T cell priming function of cDC1s by promoting nuclear respiratory factor 1 (NRF1) expression and electron transport chain integrity, thereby supporting bioenergetics and NAD⁺/NADH balance. During tumor progression, mitochondrial membrane potential and volume, as well as OPA1-NRF1 signaling, declined in intratumoral cDC1s. Furthermore, intratumoral administration of cDC1s with polarized mitochondria showed immunotherapeutic benefits in mice, particularly in combination with immune checkpoint blockade. Collectively, our findings reveal mitochondrial metabolism and signaling as putative targets to reinvigorate cDC1 function for cancer immunotherapy.

A pointed play explores what happens when scientists sell out to help a billionaire live forever.

Cell reprogramming can be used to short-circuit the cancer-immunity cycle.

Editors’ selections from the current scientific literature

Physical gas entrapment can be a platform for therapeutic gas delivery.

Conversations abound about how artificial intelligence (AI) is changing the world. AI and its applications are advancing at a pace that outstrips regulatory and ethical frameworks. In the face of these challenges, higher education must develop students into fluent, intelligent, and ethical users of AI and work to ensure that the benefits of AI reach broadly across communities.

The gut microbiota, immune system, and enteric nervous system interact to regulate adult gut physiology. However, the mechanisms establishing gut physiology during development remain unknown. We report that in developing zebrafish, enteroendocrine cells produced interleukin-22 (IL-22) in response to microbial signals before lymphocytes populated the gut. In larvae, IL-22 shaped the gut microbiota, increasing Lactobacillaceae abundance and ghrelin expression to promote gut motility. Impaired motility and ghrelin expression were restored in il22 −/− zebrafish by transfer of microbiota from wild-type zebrafish or by introducing only Lactobacillus plantarum . IL-22–deficient mice also had impaired gut motility and reduced ghrelin expression in early life, indicating a conserved function. Thus, before immune system maturation, enteroendocrine cells regulate early-life gut function by controlling the microbiota through IL-22.

Highlights from the Science family of journals

A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.

The industrialization of global food systems has led to dietary changes that harm both health and the environment. If global food systems are to meet the needs of a growing population for healthy, environmentally sustainable, and affordable diets, substantial changes will be required. In this Review, we synthesize growing empirical evidence on the complexity of factors that influence consumer dietary and farmer production choices, especially the roles of public and private entities that shape food environments. We outline promising interventions to help facilitate beneficial global dietary transitions, including research and development for product innovation, regulation of food environments, and food assistance and food-as-medicine programs. Understanding and aligning the motives and incentives of various food system actors is essential to achieve improved health, environment, and equity outcomes.

A child-centered, research-driven approach aligns protection with rights, agency, and well-being through design.

Hospitals and researchers struggle to cope with lengthy blackouts and supply shortages.

A subset of dendritic cells relies on mitochondrial fitness to trigger antitumor responses in mice.