Developing sustainable and atom-economical hydrogen transfer routes for constructing pharmacologically valuable quinoline scaffolds from abundant alcohol feedstocks remains a significant challenge. Herein, a tailored pyridinic-nitrogen-coordinated cobalt (Co) single-atom catalyst (Co-N/C-U) is showcased, enabling the efficient synthesis of quinoline derivatives from inexpensive and readily available 2-nitrobenzyl alcohol and various secondary or primary alcohols via a cascade hydrogen transfer process followed by annulation. Characterization confirmed that Co-N/C-U contains atomically dispersed Co centers and exhibits exceptional catalytic activity, accessing quinolines with up to 98% yield across a broad substrate scope (47 examples) with a turnover number of up to 30,808, outperforming state-of-the-art catalytic systems. This strategy demonstrates scalability to gram-scale reactions and enables the synthesis of the Cavosonstat derivative, while the pronounced stability and reusability of the catalyst further underscores its promising potential for practical implementation. Mechanistic studies revealed that the pyridinic-N-Co moiety plays a dual role, where the isolated Co sites facilitate efficient hydrogen transfer, and the neighboring pyridinic-N atoms act as basic sites to promote the key Friedländer cyclization step. Density functional theory calculations revealed that the enhanced catalytic performance of Co-N/C-U originates from its optimized pyridinic-N-Co coordination environment. This work establishes a sustainable route to a wide range of quinolines, providing a foundation for the precise design of next-generation SACs for complex organic transformations.
Metamaterial absorbers have been extensively investigated for broadband light harvesting and narrowband sensing, but integrating both into one compact device still remains challenging. In this work, we propose a bifunctional metamaterial absorber (BMA) based on zirconium nitride (ZrN). The device consists of periodically arranged ZrN concentric-ring arrays on a silicon dioxide (SiO2) spacer with an Au film underneath for broadband absorption, and ZrN-based four-by-four square-grid arrays on the opposite side of the Au substrate for narrowband refractive index sensing. Numerical simulations show that the broadband mode achieves an average absorptivity of 97.48% over the wavelength range of 800 to 2,300 nm, while the narrowband mode exhibits a near-perfect absorptivity at 948.1 nm with a bandwidth of 23.14 nm, delivering a sensitivity of 1,015.62 nm RIU-1. Electric field distributions and impedance analyses indicate that the absorption behavior arises from the couplings of localized surface plasmon resonances, multipole resonances, and Rayleigh Anomalies (RAs). Parametric studies demonstrate that the broadband absorption maintains high absorptivity in a wide wavelength range, whereas the narrowband resonance systematically shifts as the varying structural parameters. These results not only highlight the importance of integrating light harvesting and refractive index sensing in a single design, but also pave the way for incorporating multiple functionalities into one compact device for broad applications.
The development of high-performance self-recoverable near-infrared (NIR) mechanoluminescent materials is crucial for advancing applications. In this work, we presented a self-recoverable NIR mechanoluminescent material, platelike SrAl12O19, through singly doped with Cr3+ and co-doped with lanthanide ions (Nd3+, Yb3+, Er3+) in one step. By modulating the Cr3+ doping concentration, we achieved precise control over the mechanoluminescence (ML) intensity as well as the spectral tunability between characteristic R-line emission (~ 690 nm) and the broadband emission (750-950 nm). Moreover, energy transfer from Cr3+ to lanthanide ions enables multispectral ML emission extending into the NIR-II window (1,000-1,700 nm). The resultant material exhibits excellent ML self-recoverability and high chemical stability. The co-doped system was demonstrated with great potential in dynamic stress visualization, naked-eye-invisible information encryption and special identification under challenging conditions (e.g., underwater). We further demonstrated practical applications by fabricating dual-mode flexible NIR mechanoluminescent paper sheets and sprayable coatings. This work contributes to the advancement of new NIR mechanoluminescent materials with unique morphological features for various scenarios, including the advancement of intelligent sensing and multi-level anti-counterfeiting technologies.
Classical constitutive models explicitly couple macroscopic mechanical responses with underlying microstructural evolution, which is crucial for capturing complex deformation mechanisms across varying strain rates. However, current deep learning (DL) constitutive models predominantly focus on macroscopic stress-strain mapping, often neglecting these critical microstructural transitions. To bridge this gap, this work proposes a mechanics-informed deep learning constitutive model (MIDLCM) that integrates gated recurrent units and multi-head attention with a mechanics-informed layer and a mechanics-informed loss, enabling simultaneous prediction of stress response and microstructural descriptors. Trained on a CrFeNi FCC alloy dataset spanning strain rates from 10-4 to 5,000 s-1, MIDLCM accurately reproduces strain-rate-dependent stress-strain behavior and captures the associated evolution of dislocation density and twin volume fraction. Crucially, the model successfully represents the distinct dislocation accumulation regimes and the dynamic transition of plasticity mechanisms - from dislocation-dominated to twinning-assisted - across extreme dynamic loading, consistent with experimental trends and crystal-plasticity-based references. Ablation studies show that attention-based temporal encoding and mechanics-informed constraints contribute complementary improvements while preserving inference efficiency. By explicitly tracking these internal state variables, the proposed framework provides a mechanism-level interpretable and computationally efficient microstructure-mechanics coupled alternative for rate-dependent constitutive modeling and is readily extendable to other alloy systems and loading paths.
The dimensionless figure of merit ZT is the key metric for quantifying thermoelectric performance; however, its optimization is inherently limited by the intrinsic coupling between electrical and thermal transport properties. Herein, we perform first-principles calculations using the temperature-dependent effective potential method to investigate cation alloying in SnSe, where Sn2+ ions were randomly substituted by aliovalent cations - specifically Na+ and Sb3+ - a strategy that induces chemical bond synergy in NaSn2SbSe4, effectively decoupling electronic and phonon transport behaviors. Random cation occupation induces a mixed covalent-ionic bonding character, generating local bond-strength fluctuations that act as phonon-scattering centers. Furthermore, localized Sb-Se and Sn-Se antibonding states below the Fermi level correlate with the softening of low-frequency optical phonon branches. Combined with pronounced lattice anharmonicity, this phonon softening significantly enhances four-phonon scattering rates and suppresses the lattice thermal conductivity. Concurrently, aliovalent cation incorporation promotes electron delocalization between Sn-5p and Se-4p orbitals and strengthens covalent bonding character. This modified orbital hybridization alters band dispersion, reducing the hole effective mass while preserving high electrical conductivity in NaSn2SbSe4. The optimal balance between low lattice thermal conductivity and high power factor yields superior thermoelectric performance for NaSn2SbSe4 relative to SnSe across the entire temperature range, with a peak ZT of 0.88 at 800 K. This study establishes chemical bonding engineering as a promising strategy for enhancing thermoelectric performance and provides guidance for exploring high-performance high-entropy thermoelectric materials.
Ultrafast transmission electron microscopy (UTEM) is an advanced experimental technique that integrates a femtosecond (fs) laser with transmission electron microscopy to capture material dynamic processes at exceptionally high spatiotemporal resolution. This review aims to provide an overview on the recent progresses on UTEM from technical principles, instrument developments to scientific applications and future prospects. The fundamental operation principle of UTEM involves exciting the sample with a pump laser/electric pulse, followed by probing with a time-delayed electron pulse. By precisely varying the delay time between the pump and probe pulses, electron imaging, diffraction or spectroscopy at fs-nanometer/atomic scale can be achieved. Based on these capabilities, these advances have recently culminated in techniques such as five-dimensional scanning transmission electron microscopy and Attosecond electron microscopy, which push the boundaries toward quantitative strain mapping and sub-cycle dynamics. UTEM has demonstrated significant applications in the study of microscopic dynamics in correlated materials, semiconductors, catalysts, nanophotonics, etc. It enables direct visualization of fundamental dynamic processes such as carrier relaxation, lattice vibrations, phase transitions, near-field evolution and magnetic domain switching, etc., thereby deepening the understanding of non-equilibrium states and providing critical insights for the design of novel functional devices. With ongoing advancements in fs electron sources and high-sensitivity electron detectors, the temporal resolution and detection sensitivity of UTEM continue to improve, highlighting its substantial potential in nanometer/atomic-scale ultrafast science. Future technique developments are expected to drive major breakthroughs in condensed matter physics, materials science, chemical reactions and even biological structure dynamics, offering a powerful tool for exploring the ultrafast microscopic world.
Targeted protein degradation (TPD) technology offers a revolutionary approach for precise intervention against “undruggable” targets by exploiting intracellular pathways such as the ubiquitin-proteasome system and the autophagy-lysosome system. However, its clinical translation faces significant challenges, including limited delivery efficiency, poor tissue specificity, and off-target toxicity. The integration of nanotechnology with TPD not only overcomes the physicochemical limitations of traditional TPD molecules [e.g., Proteolysis-Targeting Chimeras (PROTACs), Autophagosome-Tethering Compounds (ATTECs), Lysosome-Targeting Chimeras (LYTACs), molecular glues] through the design of functionalized carriers but also equips these systems with spatiotemporal precision activation via diverse regulation of “initiation conditions”. This review systematically traces the developmental trajectory and fundamental mechanisms of TPD technology, explores the delivery characteristics and principles of functional modification in nanocarriers, and comprehensively discusses the design strategies, mechanisms, and recent advances of nanotyped TPD systems categorized by their initiation conditions: endogenous microenvironment-responsive [pH, enzyme, reactive oxygen species (ROS)/glutathione (GSH)], exogenous stimulus-initiated (light, magnetic, ultrasound, bioorthogonal reaction), and multi-conditionally co-initiated systems (endogenous-endogenous and endogenous-exogenous signal synergy). Furthermore, this review highlights key challenges in the field, such as carrier biocompatibility, modulation of degradation efficiency, and in vivo fate tracking, while outlining critical directions for clinical translation, including personalized customization, intelligent logic gating, and multimodal characterization. By providing a systematic theoretical framework and practical insights, this review aims to promote cross-disciplinary integration and foster innovative drug development at the intersection of nanotechnology and TPD.
Pyrochlore-type oxides are considered potential oxide-ion conductors due to their high concentration of oxygen vacancies in the unit cell. In this work, the pyrochlore-type Ca1.46Ti1.38Nb1.11O7 was synthesized and its crystal structure was characterized by Rietveld refinement. A high oxygen vacancy concentration in the material was confirmed by thermogravimetry (TG) and X-ray photoelectron spectroscopy (XPS). TG, XPS, and electron paramagnetic resonance collectively demonstrated the change in oxygen vacancy concentration of the material following atmosphere switching. The electrical properties of Ca1.46Ti1.38Nb1.11O7 under different atmospheres were characterized by electrochemical impedance spectroscopy. The conductivity of Ca1.46Ti1.38Nb1.11O7 was
The plasticity of bulk metallic glasses (BMGs) is closely correlated with the nature of shear bands; however, the structural origin of shear bands remains elusive due to the difficulty of obtaining direct observations. In this study, we investigated the microstructural evolution of shear bands during thermal relaxation by examining the local atomic-scale response to heating. Zr52.5Cu17.9Ni14.6Al10Ti5 BMGs were subjected to two specifically designed deformation methods, namely, cold rolling and high-pressure torsion (HPT), to generate shear bands with varying volume fractions and rejuvenation states. In situ synchrotron diffraction results revealed a more pronounced growth of medium-range ordering at sub-Tg temperatures in the deformed BMGs than in the as-cast sample. The HPT-deformed BMG, with the highest volume fraction and distribution complexity of shear bands, demonstrated the most rapid increase in the ordering process. The transition of cluster connection modes possibly explained the anomalous emergence of medium-range order in the shear bands of deformed BMGs during sub-Tg relaxation or tension. Our study offers new insights into the atomic structure origins of shear bands, contributing to a deeper understanding of BMG plasticity.
Artificial olfaction, inspired by biological sensory systems, offers new opportunities in environmental, industrial, and healthcare applications. Semiconducting metal oxide based chemoresistive gas sensors provide a scalable and core interface for chemical detection and therefore constitute the most extensively explored front end for artificial olfactory systems. Nevertheless, conventional chemoresistive sensing that relies on surface charge transfer remains constrained by incomplete response and recovery, humidity interference, cross selectivity, and strong temperature dependence. This review surveys material- and device-level strategies developed to address these bottlenecks, with an emphasis on nanostructuring approaches that improve gas accessibility and reaction kinetics. Moving beyond device-level performance, the review further situates oxide-based gas sensing within a hierarchical neuromorphic olfactory framework. In biological systems, chemical information is represented by distributed activation patterns and temporal dynamics that extend beyond individual receptor responses. Within this broader context, emerging oxide-based transduction concepts that extend conventional chemoresistive operation are also discussed. Recent artificial olfactory system studies have begun to explore alternative oxide-based transduction mechanisms that extend beyond conventional chemoresistive operation. Among these emerging approaches, chemo-memristive responses based on vacancy-mediated ion redox processes are briefly discussed as one possible pathway toward more tightly coupled sensing and signal encoding at the device level. Such developments reflect ongoing efforts to more closely couple sensing and signal processing at the device level. By integrating insights from nanostructured oxide sensors and neuromorphic encoding principles, this review outlines conceptual pathways toward artificial olfactory systems that extend beyond standalone gas detection toward more integrated sensory information processing architectures.
The development of highly efficient microwave absorbers presents a significant challenge, driven by the growing issue of severe electromagnetic pollution. In this context, precise structural design emerges as a decisive factor for enhancing the microwave absorption capabilities. In this work, the hollow Ni0.5Zn0.5Fe2O4/C/Ni microspheres were fabricated through hydrothermal method, calcination treatment and further annealing. The results of the morphology observation demonstrate that the heterogeneous Ni0.5Zn0.5Fe2O4/C/Ni composites are hollow microspheres, consisting of many nanoparticles. Strikingly, the appearance of metallic Ni alongside increased carbon graphitization results from the partial reduction of Ni2+ by carbon during high-temperature annealing in the Ar atmosphere, which can be beneficial to the dielectric loss. The hollow Ni0.5Zn0.5Fe2O4/C/Ni microspheres possess outstanding microwave absorption capabilities, mainly owning to the better interface and dipole polarization, eddy current loss, conduction loss and natural resonance loss, multiply reflection and scattering between the microspheres. The hollow Ni0.5Zn0.5Fe2O4/C/Ni microspheres annealed at 700 °C exhibited an optimal reflection loss (RL) value of -35.79 dB at 2.5 mm and an effective absorption bandwidth (EAB) of 5.29 GHz at 2.0 mm. The present study reveals a design approach for heterostructures, which offers novel insights into the fabrication of high-performance microwave absorbing materials.