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An innovative plasmon-mediated electron emission (PMEE) nanocathode is developed through gold nanoparticle-decorated vertically aligned few-layer graphene, enabling synchronized generation of picosecond electron pulses and GHz electromagnetic radiation. This room-temperature system achieves exceptional performance of 8.81 × 109 A·m−2·sr−1·V−1 brightness and 0.97 eV energy spread, while operating at moderate excitation, offering a promising platform for compact and high-efficiency vacuum electronic devices.

Abstract

Vacuum electronic devices offer superior electron mobility and spatiotemporal electron manipulating precision, with recent challenges focusing on ultrafast electron pulses for high-frequency, high-energy, and high-resolution applications. Plasmon-mediated electron emission (PMEE) nanocathodes provide a promising solution by producing high-quality ultrafast electron pulses while simplifying the electron beam manipulation. In this study, we developed a PMEE Au-on-Gr nanocathode using vertically aligned few-layer graphene decorated with gold nanoparticles, enabling synchronized generation of picosecond pulsed electron beam and electromagnetic radiation. The nanocathode achieved 80 MHz electron pulses with a 500 ps pulsewidth, 0.91 A·cm−2 peak current density, 6.53% external quantum efficiency, and 8.81 × 109 A·m−2·sr−1·V−1 reduced brightness. Additionally, it exhibited a 7.1° divergence angle and 0.97 eV energy spread under low excitations. Synchronized radiation pulses at 2.3, 5.7, and 9.2 GHz corresponded to electron pulse features. The excellent performance stems from plasmonic field enhancement and efficient hot electron generation driven by localized surface plasmon resonance (LSPR) in the PMEE nanocathode. The dynamic effects of high-energy hot electron injection at the Au-Gr interface also play a critical role. This system enables compact, room-temperature, low-power vacuum electronic devices for ultra-high spatiotemporal resolution and high-frequency applications, driving progress in materials science and nanotechnology.

The study explores how interfacial redox mediation influences Mn2⁺/MnO₂ conversion, focusing on local environmental regulation. It is found that the VO2⁺/VO₂⁺ redox couple stabilizes pH, controls H₂O activity, and mediates Mn3⁺, enabling 100% Mn2⁺/MnO₂ conversion. This approach suppresses Mn degradation, extends electrode lifespan, and achieves record-high electrode capacity (100 mAh cm− 2), offering a breakthrough for static Mn2+/MnO2 batteries.

Abstract

Manganese dioxide (MnO2) deposition/dissolution (Mn2+/MnO2) chemistry, involving a two-electron-transfer process, holds promise for safe and eco-friendly large-scale energy storage. However, challenges like electrode/electrolyte interface environment fluctuations (H+ and H2O activity), irreversible Mn degradation, and limited understanding of degradation mechanisms hinder the reversibility of the Mn2+/MnO2 conversion. This study demonstrates a vanadyl/pervanadyl (VO2+/VO2 +) redox-mediated interface designed for high-energy Mn2+/MnO2 batteries. Unlike flow systems, this work uncovers, for the first time, the mechanism of a static redox-mediated interface in regulating interfacial H+ and H2O activities. Significantly, the VO2+/VO2 + chemical redox mediation targets Mn3+ intermediates, suppressing their hydrolysis and enabling 100% Mn2+/MnO2 conversion. The redox-mediated interface enhances the Mn redox electron transfer process, achieving a stable ≈95% coulombic efficiency and ultrahigh capacity of 100 mAh cm− 2 with an areal energy density of 111 mWh cm− 2, outperforming flow systems. The electrode also exhibits an average specific capacity of 593 mAh g−1, approaching the theoretical limit of 616 mAh g−1, and a specific energy density of 721 Wh kg−1 at high MnO2 loadings (50–150 mg cm−2). The findings highlight the critical role of interfacial redox mediation in regulating H+ and H2O activities and underscore the significance of interface dynamics.

This study presents a “plug-and-display” strategy for constructing T cell nanoengagers by directly embedding genetically engineered lipid-tagged antibodies into lipid-based nanoparticles. This versatile approach enables the design of both bi- and tri-specific nanoengagers, which effectively recruit T cells to tumor cells, enhance T cell-mediated cytotoxicity, and mitigate T cell exhaustion.

Abstract

T cell engagers, which bind tumor-associated antigens and T cell specific molecules, represent a promising class of immunotherapies for enhancing targeted immune responses. Here, a “plug-and-display” platform is introduced for engineering T cell nanoengagers by anchoring antibody fragments into lipid-based nanoparticles. This approach utilizes a genetically engineered lipoprotein fused with single-chain variable fragments (scFv) and nanobodies, which spontaneously integrate into lipid bilayer of the nanoparticles, achieving a high surface density of at least 0.102 scFv nm−2 (≈3200 scFv per particle). Modular bi-specific (Lipo-BiTE) and tri-specific (Lipo-TriTE) immunoliposomes are designed to enhance anti-tumor T cell immune responses. The Lipo-BiTE, integrating anti-CD3 and anti-HER2 scFv at an optimized surface density of 1.28 × 10−3 scFv nm−2, exhibits enhanced CD8+ T cell-mediated cytotoxicity in HER2-positive tumor models by simultaneously engaging tumor cells and T cells. Incorporating anti-PD-L1 nanobodies to create Lipo-TriTE further addresses T cell exhaustion. This modular platform provides a robust foundation for designing immune cell engagers, with broad applications in targeted immunotherapy.

A superwetting-enabled in situ silicification strategy is proposed to fabricate artificial silicified wood without high pressure and high temperature. The artificial silicified wood exhibits super flexural strength (≈216.49 MPa) and resistance to termites (98.70% mass retention) and fungi (over 90.64% mass retention), meeting the highest AWPA and ASTM standards. This method offers a promising approach to the conservation of wooden artifacts.

Abstract

Wooden artifacts have attracted comprehensive concern as the witnesses of human civilization; however, their conservation suffers from many difficulties, such as natural degradation and biological invasion. Silicified wood, as a fossil material that has existed for millions of years, provides a valuable clue for the long-term conservation of wooden materials. In this work, a superwetting-enabled in situ silicification strategy is reported to silicify wood in a confined way, fabricating artificial silicified wood within 100 h. The superwetting process of the silica sol enables multi-scale high silica filling throughout the entire wood from the nanoscale to the macroscale. The artificial silicified wood shows a high flexural strength of ≈216.49 MPa and super resistance against termites and fungi. The artificial silicified wood retains 98.70% of its mass against termites, and over 90.64% of its mass against fungi, meeting the safest level in the global standards. The finding provides a general silicification approach for wood-like materials with complex hierarchical structures and a promisingly alternative solution for the conservation of wooden artifacts.

A novel near-infrared II J-aggregate-based nanomedicine has been observed to target tumor tissue and achieve effective penetration and prolonged retention in tumor tissue using an in situ secondary self-assembly strategy. These nanomedicines induce tumor pyroptosis by generating type I reactive oxygen species (superoxide anions), facilitating robust NIR-II fluorescence imaging and activating tumor photoimmunotherapy.

Abstract

Pyroptosis, a programmed cell death mechanism that bypasses apoptosis resistance and triggers tumor-specific immune responses, has gained much attention as a promising approach to cancer therapy. Despite enhancing tumor accumulation and extending the circulation of small-molecule drugs, nanomedicines still face significant challenges, including poor tissue penetration, tumor resistance, and hypoxic microenvironments. To overcome these challenges, a novel near-infrared II (NIR-II) J-aggregate-based nanomedicine is designed, leveraging an in situ secondary self-assembly strategy to fabricate highly targeted nanoparticles (MSDP NPs). These nanomedicines trigger pyroptosis by generating type I reactive oxygen species, especially superoxide anions, while simultaneously activating photoimmunotherapy. In vivo studies demonstrate that MSDP NPs achieve efficient tumor penetration and prolong tumor retention, which is facilitated by the J-aggregate-driven formation of microscale spindle-shaped fibrillar bundles through in situ secondary self-assembly at the tumor site. This unique structural transformation enhances nanomedicine accumulation in tumor tissues, enabling robust NIR-II fluorescence imaging and improving therapeutic efficacy even in hypoxic tumor microenvironments. This study provides an innovative phototheranostic strategy that utilizes the in situ secondary self-assembly of NIR-II J-aggregates to induce tumor pyroptosis, offering a potential solution to the limitations of current nanomedicines in cancer therapy.

Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D5EE00458F, PaperYang Yang, Shuyuan Wan, Hang Wei, Lijun Yang, Zhiyuan Dai, Haoze Lu, Zhe Liu, Bo Chen, Ruihao Chen, Hongqiang Wang
Perovskite solar cells (PSCs) suffer from instability under prolonged exposure to light, moisture, and heat, primarily due to uncoordinated ionic defects. Current strategies primarily focus on using solid-state molecules to...
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Nature Materials, Published online: 22 April 2025; doi:10.1038/s41563-025-02225-7

The authors report their observation of the fractional quantum anomalous Hall effect in rhombohedral hexalayer graphene/hBN moiré superlattice devices.

Nature Energy, Published online: 22 April 2025; doi:10.1038/s41560-025-01759-z

Lessons learned from Los Angeles’s just energy transition initiative

Title tbc

Abstract not available

• Speaker: Mariusz Mirek (Rutgers University)
• Wednesday 28 May 2025, 13:30-15:00
• Venue: MR4, CMS.
• Series: Discrete Analysis Seminar; organiser: Julia Wolf.

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Title tbc

Abstract not available

• Speaker: Max Xu (Courant Institute, NYU)
• Wednesday 21 May 2025, 13:30-15:00
• Venue: MR4, CMS.
• Series: Discrete Analysis Seminar; organiser: Julia Wolf.

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Convergence for sparse graphs and representations

Various modes of convergence can be defined to control the asymptotic `global’ properties of a growing sequence of sparse graphs. Variants of these that allow directed and labeled edges have appeared independently in the study of sofic entropy in ergodic theory. In both settings, the theory has run into fundamental open questions about the convergence of some basic examples, especially random regular graphs. In the first part, I will sketch some of these questions with their background. In the second part, I will describe some analogs for unitary representations that have answers in terms of operator algebras. I will also indicate some applications to the study of random matrices if time allows.

(A more elementary account of some of these topics will occupy the Mordell lecture on Thursday.)

• Speaker: Tim Austin (University of Warwick)
• Wednesday 30 April 2025, 13:30-15:00
• Venue: MR4, CMS.
• Series: Discrete Analysis Seminar; organiser: Julia Wolf.

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Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D5EE00605H, PaperYuhao Guo, Qinhui Guan, Xingjuan Li, Mengjun Zhao, Na Li, Zizhong Zhang, Gui-qiang Fei, Tingjiang Yan
In heterogeneous photocatalysis, the dynamics of charge carriers holds particular significance for comprehending the underlying catalytic mechanism and designing highly efficient photocatalysts. The current technological challenge lies in how to...
The content of this RSS Feed (c) The Royal Society of Chemistry

Here, the study reports morphotropic phase boundary like behavior in a relaxor ferroelectric polymer with a unique head-to-head/tail-to-tail chain structure by the complete hydrogenation of poly(vinylidene fluoride-chlorotrifluoroethylene), achieving an outstanding piezoelectric coefficient of −107 pC/N, over five times higher than commercial polyvinylidene difluoride. This breakthrough enables next-generation high-performance flexible devices.

Abstract

During past decades, the construction of morphotropic phase boundary (MPB) behavior in ceramic-based relaxor ferroelectrics has successfully led to a significant enhancement in the piezoelectric coefficient for actuators, transducers, and sensors application. However, MPB-like behavior is achieved only in the ferroelectric state in flexible ferroelectric polymers such as poly(vinylidene fluoride-trifluoroethylene) with the highest piezoelectric coefficients of ≈−63.5 pC/N, due to the lack of a rational design in polymer chain structure and composition. Here, the study reports the first MPB-like behavior observed in a relaxor ferroelectric polymer synthesized by fully hydrogenating poly(vinylidene fluoride-chlorotrifluoroethylene), which are primarily linked in a head-to-head/tail-to-tail manner, and trifluoroethylene units are randomly dispersed along the molecular chain. The unique polymer chain structure is found to be responsible for the formation of conformations disorder, thus strong relaxor behavior, and phase transition from an all-trans conformation to 3/1 helix, thus inducing phase boundary behavior. As a result, an outstanding longitudinal piezoelectric coefficient of −107 pC/N, more than five times higher than that of commercial poly(vinylidene fluoride) (−20 pC/N), is observed. This work opens up a new gate for next-generation high-performance flexible devices.

A microphase separation-driven supramolecular tissue adhesive based on guanidinium-functionalized polydimethylsiloxane exhibits instantaneous adhesion in both dry and wet environments. In the meantime, this material demonstrates the capacity for antibacterial hemostasis upon application to biological tissues and can be readily removed from tissue surfaces through wet wiping with medical-grade alcohol.

Abstract

Tissue adhesives are promising materials for expeditious hemorrhage control, while it remains a grand challenge to engineer a superior formulation with instantaneous adhesion, on-demand debonding, and the integration of multiple desirable properties such as antibacterial and hemostatic capabilities. Herein, a multifunctional supramolecular tissue adhesive based on guanidinium-modified polydimethylsiloxane (PDMS) is introduced, driven by a reversible microphase separation mechanism. By optimizing the content of guanidinium ions, precise control over cohesive strength, adhesion, and wettability is achieved, resulting in strong instantaneous adhesion under both dry and wet conditions. Notably, the supramolecular nature of the adhesive allows for convenient on-demand removal using medical-grade alcohol, offering a critical advantage for easy debonding. Additionally, the adhesive exhibits remarkable antimicrobial properties while maintaining excellent biocompatibility and hemocompatibility. Its underwater injectability supports minimally invasive surgical procedures. Furthermore, the adhesive's ability to incorporate solid particles enhances its versatility, particularly for the development of drug-embedded bioadhesives. This work addresses key challenges in tissue adhesive design via a microphase separation-driven working principle, thereby opening promising new avenues for the development of advanced bioadhesives with tailored properties and enhanced surgical and wound care outcomes.

This research introduces an aerogel apheresis device specifically designed for hyperlipidemia management in elderly patients. Leveraging the unique properties of aerogels, LipClean achieves selective lipid adsorption from plasma while maintaining efficiency and biocompatibility. The optimized hydrophilic-hydrophobic network ensures effective water permeability and reduces the unintended removal of essential plasma components.

Abstract

Elderly patients with hyperlipidemia often exhibit resistance to conventional hypolipidemic treatments, underscoring the need for more effective strategies to address lipid imbalances in this high-risk group. This study introduces LipClean, an aerogel-based apheresis device specifically designed to remove harmful plasma lipids. LipClean is constructed using hydrophilic cellulose fibers, which serve as a supramolecular platform for synthesizing hydrophobic conjugated polymers through a Sonogashira-Hagihara reaction. These conjugated polymers are then cross-linked with the cellulose fibers via phosphorylation, generating an aerogel monolith with an interpenetrating network of hydrophilic fibers and hydrophobic polymers. Unlike bilayer aerogels that separate hydrophilic and hydrophobic layers, LipClean's interpenetrating structure is precisely engineered through polymer design and gradient cross-linking. This optimization enhances both bodily fluid flow and lipid adsorption while minimizing the removal of essential plasma components and ensuring unobstructed cell passage. In preclinical testing, LipClean significantly reduced triglyceride and cholesterol levels in an elderly rat model of hyperlipidemia and normalized lipid levels in blood samples from hypertensive patients. Importantly, purified blood maintained normal levels of blood cells and physiological and biochemical indicators after apheresis, highlighting LipClean's potential for managing hyperlipidemia-related disorders. This study, therefore, underscores the importance of interdisciplinary collaboration in driving medical device innovation.

It is shown that the synthesis of solution-processable poly(3,4-ethylenedioxythiophene) (PEDOT) hole transporting materials (HTMs) follows the principle of oxidative polymerization-induced electrostatic self-assembly (OPIESA), with the kinetic behavior strongly correlated to the volume of the polyanion matrix, and propose a kinetically-controlled polymerization (KCP) approach to synthesize solution-processable, high-performance PEDOT HTMs by halting the polymerization at certain stages within a low-volume polyanion matrix.

Abstract

The updating of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transporting material (HTM) is crucial for organic solar cells (OSCs). Despite decades of development in PEDOT:PSS and its derivatives, a comprehensive understanding of their supramolecular polymerization mechanisms remains elusive, precluding the attainment of the optimal architectures and functions. Herein, it is shown that the synthesis of PEDOT:PSS follows the principle of oxidative polymerization-induced electrostatic self-assembly, with the kinetic behavior strongly correlated to the volume of PSS polyanion matrix. Moreover, a kinetically controlled polymerization approach is proposed to synthesize PEDOT HTMs with exceptional time efficiency by prematurely halting the rapid polymerization process within a low-volume PSS matrix. The reduced interference from PSS confers unique advantages to the methodology in achieving highly oxidized and interconnected PEDOTs. This leads to comprehensive improvements in the physico-chemical properties of PEDOT:PSS, significantly enhancing OSC efficiency to 20.04%. Furthermore, the optimized PEDOT maintains exceptional semiconducting characteristics and outstanding OSC efficiency even at an unprecedentedly high PSS insulator content of 94.12%. The substantial increase in loading significantly amplifies the manifestation of polyanion functionalities, such as improving colloidal stability, thereby facilitating the resurgence of previously underutilized naphthalene sulfonate polyanion in the fabrication of high-quality, solution-processable PEDOT HTMs.

An implantable wireless supercapacitor-activated neuro (W-SCAN) system consisting of the coil, diode bridge circuit, in-hydrogel supercapacitor, and stimulation electrodes has been developed for neuronal excitation and inhibition. By applying an adjustable electric field to stimulation electrodes, a spontaneously induced ionic oscillatory stimulation within tissue fluids is generated, which enables electro-interventional therapy for brain-related neurological disorders.

Abstract

The bidirectional modulation of cerebral neurons in the brain possesses enhancement and inhibition of neural activity, which is of great interest in the treatment of motor nerve disorders and emotional disorders, and cognitive defects. However, existing approaches usually rely on electrical/electrochemical stimulations, which show low security by implanting metal probes and unidirectional currents with single modulation. Herein, an implantable in-hydrogel wireless supercapacitor-activated neuron system consisting of the coil, diode bridge circuit, in-hydrogel supercapacitor, and stimulation electrodes is fabricated, which provides a bidirectional and adjustable ion diffusion current to safely and effectively excite and inhibit brain neurons. The designed in-hydrogel supercapacitor exhibits a high storage charge ability of ≈90 times larger than the devices without hydrogel encapsulation, owing to the in situ radical addition mechanism. Moreover, the in-hydrogel electrodes are implanted into the thalamus, amygdala, and prefrontal lobes of the brain to evoke the corresponding changes in potential intensity and frequency through the external chargeable coil and diode bridge circuit, which verifies the potential of the multimodule supercapacitor in amelioration and treatment Parkinson's, severe depression, and Alzheimer's disease.

Piezoelectric transduction in monolayer MoS2 is demonstrated using an ultrasound tip ( 100 kHz) from a wire bonder. Transient current measurements reveal sharp peaks with high peak-to-base ratios, tunable via gate voltage and ultrasound power. Multiple acoustic wave reflections enhance signal linewidth, validated by microacoustic simulations, establishing a robust platform for ultrasound-driven piezoelectric sensing.

Abstract

The interaction of ultrasonic waves with piezoelectric materials provides a quantitative route to enhance electrical and mechanical coupling in van der Waals (vdW) heterostructures. Here, wire-bonding tip-assisted ultrasound (≈100 kHz) is presented as an effective approach to achieve piezoelectric transduction in monolayer MoS2 on Si/SiO2 substrates. Transient current measurements show reproducible sharp peaks with a peak-to-base ratio (I peak /I base ≈ 12) unique to monolayer MoS2, under an impact duration of 10–100 ms. Electrostatic gate voltage (V g ) and ultrasound power (W P ) tunable piezocurrent exhibit 3–5 times higher sensitivity in the ON-state (V g ⩾ 0) compared to the OFF-state. Multiple reflections of acoustic waves at source-drain electrodes, with an increment in reflection coefficients, enhance the linewidth of peak currents, validated by microacoustic simulations of surface acoustic wave (SAW) propagation in submicron geometries. The localized strain and Joule heating under ultrasonic excitation may generate a temperature rise of ≈20 K, which reduces activation energy barriers, potentially enhancing reaction rates in temperature-sensitive chemical processes, such as hydrogen peroxide decomposition. This thermal-damage-free method integrates with silicon-based fabrication, establishing a robust platform for on-chip catalysis and energy harvesting in FET-based piezotransducers.

This work demonstrates stabilization of complex magnetic skyrmion bags in ferromagnetic thin films through precisely engineered anisotropy defects using ion irradiation. The researchers achieve controlled field- and laser-induced generation of skyrmionia, target skyrmions, and higher-order skyrmion bags at room temperature. This reliable platform opens opportunities for studying the dynamics of these topological textures and their implementation in advanced spintronic devices.

Abstract

Topologically non-trivial magnetic solitons are complex spin textures with a distinct single-particle nature. Although magnetic skyrmions, especially those with unity topological charge, have attracted substantial interest due to their potential applications, more complex topological textures remain largely theoretical. In this work, the stabilization of isolated higher-order skyrmion bags beyond the prototypical π-skyrmion in ferromagnetic thin films is experimentally demonstrate, which has posed considerable challenges to date. Specifically, controlled generation of skyrmionium (2π-skyrmion), target skyrmion (3π-skyrmion), and skyrmion bags (with variable topological charge) are achieved through the introduction of artificially engineered anisotropy defects via local ion irradiation. They act as preferential sites for the field- or laser-induced nucleation of skyrmion bags. Remarkably, ultrafast laser pulses achieve a substantially higher conversion rate transforming skyrmions into higher-order skyrmion bags compared to their formation driven by magnetic fields. High-resolution x-ray imaging enables direct observation of the resulting skyrmion bags. Complementary micromagnetic simulations reveal the pivotal role of defect geometry–particularly diameter–in stabilizing closed-loop domain textures. The findings not only broaden the experimental horizon for skyrmion research, but also suggest strategies for exploiting complex topological spin textures within a unified material platform for practical applications.

This study presents a DeepONet-based machine learning framework for designing stochastic mechanical metamaterials with tailored nonlinear mechanical properties. By leveraging sparse but high-quality experimental data from in situ micro-mechanical tests, high predictive accuracy and enable efficient inverse design are achieved. This approach integrates experimental mechanics and AI, advancing next-generation metamaterials for aerospace, healthcare, and energy applications.

Abstract

Machine learning (ML) is emerging as a transformative tool for the design of mechanical metamaterials, offering properties that far surpass those achievable through lab-based trial-and-error methods. However, a major challenge in current inverse design strategies is their reliance on extensive computational and/or experimental datasets, which becomes particularly problematic for designing micro-scale stochastic architected materials that exhibit nonlinear mechanical behaviors. Here, a comprehensive end-to-end scientific ML framework, leveraging deep neural operators (including DeepONet and its variants) is introduced, to directly learn the relationship between the complete microstructure and mechanical response of architected metamaterials from sparse but high-quality in situ experimental data. Various neural operators and standard neural networks are systematically compared to identify the model that offers better interpretability and accuracy. The approach facilitates the efficient inverse design of structures tailored to specific nonlinear mechanical behaviors. Results obtained from stochastic spinodal microstructures, printed using two-photon lithography, reveal that the prediction error for mechanical responses is within a range of 5 - 10%. This work underscores that by employing neural operators with advanced nano- and micro-mechanical experiments, the design of complex micro-architected materials with desired properties becomes feasible, even in scenarios constrained by data scarcity. This work marks a significant advancement in the field of materials-by-design, potentially heralding a new era in the discovery and development of next-generation metamaterials with unparalleled mechanical characteristics derived directly from experimental insights.