Browse Articles

Tunable magneto-optical Kerr effect in two-dimensional non-collinear antiferromagnetic material HfFeCl6

With the development of two-dimensional (2D) magnetic materials, the magneto-optical Kerr effect (MOKE) is widely used to measure ferromagnetism in 2D systems. Although this effect is usually inactive in antiferromagnets (AFM), recent theoretical studies have demonstrated that the presence of MOKE relies on the symmetry of the system and antiferromagnets with noncollinear magnetic order can also induce a significant MOKE signal even without a net magnetization. However, this phenomenon is rarely studied in 2D systems due to the scarcity of appropriate materials hosting noncollinear AFM order. Here, based on first-principles calculations, we investigate the HfFeCl6 monolayer with noncollinear Y-AFM ground states, which simultaneously breaks the time-reversal (T) and time-inversion (TI) symmetry, activating the MOKE even though with zero net magnetic moment. In addition, four different MOKE spectra can be obtained in the four permutation states of spin chirality and crystal chirality. The MOKE spectra are switchable when reversing both crystal and spin chirality. Our study provides a material platform to explore the MOKE effect and can potentially be used for electrical readout of AFM states.

A covalent chemical probe for Chikungunya nsP2 cysteine protease with antialphaviral activity and proteome-wide selectivity

Abstract Chikungunya is a mosquito-borne viral disease that causes fever and severe joint pain for which there is no direct acting drug treatments. Vinyl sulfone SGC-NSP2PRO-1 (3) was identified as a potent inhibitor of the nsP2 cysteine protease (nsP2pro) that reduced viral titer against infectious isolates of Chikungunya and other alphaviruses. The covalent warhead in 3 captured the active site C478 and inactivated nsP2pro with a k inact/K i ratio of 5950 M–1 s–1. The vinyl sulfone 3 was inactive across a panel of 23 other cysteine proteases and demonstrated remarkable proteome-wide selectivity by two chemoproteomic methods. A negative control analog SGC-NSP2PRO-1N (4) retained the isoxazole core and covalent warhead but demonstrated > 100-fold decrease in enzyme inhibition. Both 3 and 4 were stable across a wide range of pH in solution and upon prolonged storage as solids. Vinyl sulfone 3 and its negative control 4 will find utility as high-quality chemical probes to study the role of the nsP2pro in cellular studies of alphaviral replication and virulence.

Topology‐Oriented Lymph Node Drainage of Dendritic Polymer‐TLR Agonist Conjugates to Enhance Vaccine Immunogenicity

AbstractStrategically targeting lymph nodes (LNs) to orchestrate the initiation and regulation of adaptive immune responses is one of the most pressing challenges in the context of vaccination. Herein, a series of polymer‐TLR agonist conjugates (PTACs) is developed to investigate the impact of dendritic‐topological characteristics on their LN targeting activity in vivo, and their molecular weight (MW) on their pharmacokinetics in support of their LN homing. Notably, the dendritic 6‐arm PTAC with a MW of 60 kDa (6A‐PTAC‐60k) rapidly delivered cargo to draining LNs after administration to peripheral tissues. Specifically, this topologic structure ameliorated the targeting behavior within lymphatic vessels and LNs, including an elevated amount of TLR7/8 agonist delivered to the LNs, an improved distribution pattern among barrier cells and immune cells, increased permeability, and prolonged retention. Furthermore, the 6A‐PTAC‐60k formulation induced broad antibody and T cell responses, enhancing vaccine immunogenicity and suppressing tumor growth. The results revealed that both the topology and MW of polymers are crucial factors for immunoadjuvant distribution and their functional activity in the draining LNs, which, in turn, enhanced the immunogenicity of the vaccine formulation. This study may provide a chemical and structural basis for optimizing the design of immunoadjuvant delivery systems.

Interfacial Atomic Mechanisms of Single‐Crystalline MoS₂ Epitaxy on Sapphire

AbstractThe epitaxial growth of molybdenum disulfide (MoS₂) on sapphire substrates enables the formation of single‐crystalline monolayer MoS₂ with exceptional material properties on a wafer scale. Despite this achievement, the underlying growth mechanisms remain a subject of debate. The epitaxial interface is critical for understanding these mechanisms, yet its exact atomic configuration has previously been unclear. In this study, a monolayer single‐crystalline MoS₂ grown on a sapphire substrate is analyzed, decisively visualizing the atomic structure of the epitaxial interface and elucidating its role in epitaxial growth from an atomic perspective. The findings reveal that the interface consists of a periodic molecular MoO3 interlayer, van der Waals epitaxially grown on a single Al‐terminated sapphire surface. Additionally, it is discovered that MoO3 coverage enhances surface interactions and introduces a unique atomic arrangement with 1‐fold symmetry at the sapphire surface, thereby facilitating the unidirectional alignment of MoS₂. This discovery provides valuable insights into the growth mechanisms leading to single‐crystalline MoS₂ formation, and suggests pathways for quantitatively monitoring and controlling growth dynamics, for the improvement of material quality and process repeatability, applicable for single‐crystalline MoS₂ or potentially other transition metal dichalcogenides epitaxially grown on sapphire.

Near-field enhanced solid-state thermionic power generation

The lack of low-work function materials and the negative space charge effect have long prevented vacuum thermionic energy converters (VTECs) from becoming a practical means of power generation. Advancements in microfabrication have since provided solutions to these challenges, such as the suppression of negative space charge via a micro/nanoscale interelectrode vacuum gap distance, reigniting interest in VTECs as a potential clean energy technology. However, the limited operational lifetimes of many low-work function coatings have hindered their practical device-level implementation. Solid-state thermionic energy converters (SSTECs) have been proposed as a viable alternative to VTECs since they do not require an interelectrode vacuum gap or low-work function electrodes. Nevertheless, SSTECs still require a large temperature gradient between electrodes and are limited to low operating voltages. To address these limitations, we propose a near-field enhanced solid-state thermionic energy converter (NF-SSTEC), which leverages the advantages of SSTECs by eliminating the need for a large temperature gradient between the electrodes and increasing the range of possible operating voltages. We theoretically demonstrate conversion efficiencies of 16.8 % and power densities as high as 13.1 W cm−2 without needing a high-temperature gradient between the radiator and SSTEC. Additionally, we compare its performance under different radiation spectra, showing the potential for improvement via further optimization of the radiator.

Association between FT4/FT3 ratio and microalbuminuria in euthyroid patients with type 2 diabetes mellitus

In Situ, Treatment with Guanidinium Chloride Ligand Enables Efficient Blue Quantum Dot Light‐Emitting Diodes with 23.5% External Quantum Efficiency

Abstract The poor efficiency and stability of blue Quantum Dot Light‐Emitting diodes (QLED) hinders the practical applications of QLEDs full‐color displays. Excessive electron injection, insufficient hole injection, and abundant defects on the surface of quantum dots (QD) are the main issues limiting the performance of blue devices. Herein, an in situ treatment with bipolar small molecule polydentate ligand–guanidine chloride (GACl) is proposed to simultaneously suppress excessive electron injection, patch surface defects of QDs and enhance hole injection. GACl‐treated blue QLEDs exhibited a remarkable increase in maximal external quantum Efficiency (EQE) from 16.3% to a record 23.5%, accompanied by maximal luminance (36810 cd m −2 ), excellent maximal current efficiency (17.5 cd A −1 ), and enhanced device stability. Combining C–V and J–V characteristics, a concise physical model of hole injection is also established: Below 3 V, hole injection is controlled by the interfacial barrier, primarily through tunneling and thermionic injection; Above 3 V, the interfacial barrier is eliminated, and hole injection efficiency is governed by transport within the QD layer. This study showed a clear physical model for understanding the hole injection mechanism in QLEDs, offering valuable design strategies for improving the performance of blue‐QLEDs.

The competition between van der Waals and ionic interactions at the SrTiO3/mica heterointerface

Growing a 3D film on a 2D substrate, a process often referred to as quasi-van der Waals (vdW) epitaxy, is generally believed to involve both chemical and vdW interactions at the interface. To date, the competition between chemical and vdW interactions at the interface has yet to be established. In this work, we demonstrate that the chemical activity of deposited species is crucial for determining the structure of the 3D/2D heterointerface. During pulsed laser deposition, the chemical activity of SrTiO3 (STO) can be adjusted by controlling the oxygen partial pressure. Therefore, the relative contributions of chemical and vdW interactions at the STO/mica interface can be tuned. This finding ultimately explains the coexistence of [111] and [001] orientations in STO epitaxy on mica.

Lead free perovskite integrated metal organic framework as heterogeneous catalyst for efficient three component click reaction

Electrochemically Driven Optical Dynamics of Reflectin Protein Films

AbstractNeuronally triggered phosphorylation drives the dynamic condensation of reflectin proteins, enabling squid to fine tune the colors reflected from specialized skin cells (iridocytes) for camouflage and communication. Reflectin, the primary component of iridocyte lamellae, forms alternating layers of protein and low refractive index extracellular space within membrane‐encapsulated structures, acting as a biologically tunable distributed Bragg reflector. In vivo, reflectin condensation induces osmotic dehydration of these lamellae, reducing their thickness and shifting the wavelength of reflected light. Inspired by this natural mechanism, we demonstrate that electrochemical reduction of imidazolium moieties within the protein provides a reversible and tunable method to control the water volume fraction in reflectin thin films, allowing precise, dynamic modulation of the film’s refractive index and thickness — mimicking the squid’s dynamic color adaptation. To unravel the underlying mechanisms, we developed electrochemical correlative ellipsometry and surface plasmon resonance spectroscopy, enabling real‐time analysis of optical property changes of reflectin films. This electrochemically driven approach offers unprecedented control over reflectin condensation dynamics. Our findings not only deepen the understanding of biophysical processes governing cephalopod coloration but also pave the way for bio‐inspired materials and devices that seamlessly integrate biological principles with synthetic systems to bridge the biotic‐abiotic gap.

Synergistic Control of Ferroelectric and Optical Properties in Molecular Ferroelectric for Multiplexing Nonvolatile Memory

Abstract Utilizing the correlation among diverse physical properties to facilitate multiplexing and multistate memory is anticipated to emerge as an efficient strategy to enhance memory capacity, achieve device miniaturization, and ensure information security. As an important functional material, ferroelectrics have long been considered as a potential candidate in multistate memory devices. Furthermore, the integration of optical response offers an alternative path to realizing multiplexing features, further enhancing the versatility and efficiency of these devices. However, combining ferroelectricity and optical activity is always challenging because ferroelectricity is very sensitive to the crystal structure. In this study, on the correlation between ferroelectric polarization (FP) and optical properties in molecular ferroelectric material, trimethylchloromethyl ammonium trichloromanganese (TMCM‐MnCl 3 ) is reported. This research demonstrated that the FP can modulate the photoluminescence (PL) emission, while optical illumination can trigger FP reversal. Based on these, both electric‐writing optical‐reading (EWOR) and optical‐writing electrical‐reading (OWER) modes have been conclusively established, and the seamless transition between these two modes can be achieved by adjusting the excitation light intensity. These findings reveal an intriguing physical interconnection and imply the viability of implementing multiplexing and multistate memory functionalities in systems based on ferroelectrics.

Ferroelectric control of valleytronic nonvolatile storage in HfCl2/Sc2CO2 heterostructure

Valleytronics, utilizing the valley degree of freedom in electrons, has potential for advancing the next-generation nonvolatile storage. However, practical implementation remains challenging due to the limited control over valleytronic properties. Here, we propose ferroelectric HfCl2/Sc2CO2 van der Waals heterostructure as a platform to overcome these limitations, enabling tunable and nonvolatile valleytronic behaviors. Our findings show that the electric polarization state of the Sc2CO2 monolayer governs the electronic properties of heterostructures. Positive polarization induces a direct gap at the valleys, enabling valleytronic functionality for excitation and readout via circularly polarized light, while negative polarization results in an indirect-gap, suppressing valleytronic behavior. Moreover, our transport simulations further demonstrate a polarization-dependent ferroelectric p-i-n junction with 8 nm possesses a maximum tunnel electroresistance (TER) ratio of 1.60 × 108% at a bias of 0.5 eV. These results provide insights into ferroelectric-controlled valleytronic transitions and position the HfCl2/Sc2CO2 heterostructure as a promising candidate for energy-efficient valleytronic memory and nonvolatile storage applications.

Constructing a knowledge graph-driven intelligent data-enabled design system for mold using deep semantic understanding and intelligent decision support

High‐Temperature Polymer Composite Dielectrics: Energy Storage Performance, Large‐Scale Preparation, and Device Design

Abstract Film capacitors are widely used in advanced electrical and electronic systems. The temperature stability of polymer dielectrics plays a critical role in supporting their performance operation at elevated temperatures. For the last decade, the investigations for new polymer dielectrics with high energy storage performance at higher temperatures (>200 °C) have attracted much attention and numerous strategies have been employed. However, there is currently still a large gap between lab research and large‐scale production. In this review, the main effects of high temperature on the dielectric properties are analyzed and core modification strategies are summarized. The scientific and technological reasons for the performance difference between lab research and practical application are also discussed. Further, several processes for large‐scale film preparation and typical device structure design are reviewed. The current research and product launches pertaining of high‐temperature film capacitors are also summarized. Conclusive insights and future perspectives are delineated to offer strategic direction for the ongoing and prospective innovation in polymer dielectric materials.

All optical poling of KTP crystal for phase matched second harmonic generation

We demonstrate periodic ferroelectric domain inversion in KTiOPO4 (KTP) crystals using the femtosecond laser poling technique. The effects of laser parameters on the morphological characteristics of these light-induced domains were systematically investigated. A periodically poled KTP crystal was fabricated through this optical approach, achieving quasi-phase matched second harmonic generation. This work provides a convenient method for engineering ferroelectric domains in KTP crystals and expands the applicability of all optical poling to a broader range of ferroelectric materials.

Stability analysis of carbon emission trading mechanism in China based on a tripartite evolutionary game

Si‐CMOS Compatible Synthesis of Wafer‐Scale 1T‐CrTe₂ with Step‐Like Magnetic Transition

Abstract2D room‐temperature ferromagnet CrTe2 is a promising candidate material for spintronic applications. However, its large‐scale and cost‐effective synthesis remains a challenge. Here, the fine controllable synthesis of wafer‐scale 1T‐CrTe2 films is reported on a SiO2/Si substrate using plasma‐enhanced chemical vapor deposition at temperatures below 400 °C. Magnetic hysteresis measurements reveal that the synthesized 1T‐CrTe2 films exhibit perpendicular magnetic anisotropy along with distinct step‐like magnetic transitions. It is found that 1T‐CrTe2 is susceptible to oxygen adsorption even in ambient conditions. The theoretical calculations indicate that the oxidation of surface layers is crucial for the absence of out‐of‐plane easy axis in few‐layer CrTe2, while the interlayer antiferromagnetic coupling among the upper surface layers leads to the observed step‐like magnetic transitions. The study provides a Si‐CMOS compatible approach for the fabrication of magnetic 2D materials and highlights how unintentional adsorbents or dopants can significantly influence the magnetic behaviors of these materials.

Nano‐Metal–Organic Frameworks Isolated in Mesoporous Structures

Abstract As an alternative to bulk counterparts, metal–organic framework (MOF) nanoparticles isolated within conductive mesoporous carbon matrices are of increasing interest for electrochemical applications. Although promising, a “clean” carbon surface is generally associated with poor compatibility and weak interactions with metal/ligand precursors, which leads to the growth of MOFs with inhomogeneous particle sizes on outer pore walls. Here, a general methodology for in situ synthesis of eight nanoMOF composites within mesochannels with high dispersity and stability are reported. Mesoporous polydopamine (mesoPDA)‐F127 nanospheres with unique surface chemistry, e.g., nanoconfined spaces, catechol functional groups, pyrrolic N doping, and hydrophilic PEO blocks, are found to be a suitable molecular platform. Sliced cross‐sectional TEM, HAADF‐STEM, and corresponding EDS elemental mapping, as well as nitrogen adsorption characterizations, are utilized to visualize the in situ growth process of ZIF‐8 nanoparticles. These careful analyses provides direct evidence that the highly dispersed ZIF‐8 is exclusively located inside the internal mesochannels. After moderate carbonization of the mesoPDA‐F127/ZIF‐8 nanocomposites, a prototype for a mesoporous carbon‐isolated ZIF‐8 nanostructure is achieved, which can regulate Zn 2+ plating electrochemistry toward stable aqueous Zn batteries. This is the first report of the complete impregnation and even dispersion of nanoscale MOFs within the interior channels of mesoporous carbons.

First-principles and Monte Carlo simulations of high-entropy MXenes

In this work, we developed a computational framework that integrates first-principles density functional theory (DFT) calculations with Monte Carlo (MC) algorithm to search for the most stable configuration of high-entropy (HE) MXenes. This framework can predict the minimum energy configurations of HE MXenes with interlayer segregation. For instance, DFT/MC simulation indicates that (Ti0.5Cr0.5)4C3 MXenes exhibit interlayer segregation, where Cr atoms are favorable to segregate into the outermost top and bottom layers, forming out-of-plane MXene (o-MXenes). Such an o-MXene structure was also found in (Nb0.5Mo0.5)4C3, (Cr0.5Mo0.5)4C3, and (Ti0.33Cr0.33Mo0.34)4C3 MXenes, which is in good agreement with prior studies. The classical molecular dynamics (MD)/MC simulations using machine learning interatomic potentials further validate the interlayer segregation-induced o-MXene observed in the DFT/MC simulations. This DFT/MC framework can be easily extended to predict the stable phases for other material systems, suggesting its broad applicability and impact.

[18F]FDG-PET and [18F]MPPF-PET are brain biomarkers for the creatine transporter Slc6a8 loss of function mutation

Abstract Pathogenic variants in the creatine transporter gene SLC6A8, reported to represent 2% of all intellectual disabilities in males, result in a spectrum of behavioral abnormalities including developmental delay, intellectual disability, and deficit in speech. While at present there are no effective treatments available, preclinical development and testing of gene therapy and other approaches to increase brain creatine are being actively pursued. In studying a mouse model of the disorder, [18F]fluorodeoxyglucose ([18F]FDG)-based positron emission tomography (PET)/computed tomography (CT) was performed to assess brain glucose metabolism in wild type and creatine transporter mutant mice (Slc6a8 -/y ). The findings demonstrate marked differences in glucose metabolism in the brains of wild type and Slc6a8 -/y mice. In conducting behavioral phenotyping studies, notable abnormalities in behavior in the murine model led to additional studies in serotonin-mediated activity. Serotonergic signaling differences were detected between wild type and Slc6a8 -/y mice using 4-(2′-methoxyphenyl)-1-[2′-(N-2″-pyridinyl)-p-[18F]fluorobenzamido]ethylpiperazine ([18F]MPPF). These data demonstrate that [18F]FDG-PET and [18F]-MPPF-PET may serve as appropriate and sensitive biomarkers that could be used to assess the efficacy of not only new approaches in treating mutations of the creatine transporter SLC6A8 and their effectiveness in normalizing brain metabolism but also in enhancing our understanding of the mechanism of brain dysfunction that occurs in this complex brain disorder.