Browse Articles

Parametric resonance and RF-to-THz frequency conversion in semiconductor plasmonic crystals

We show that plasma excitations in nanoscale field-effect transistor structures with periodically alternating gated and ungated regions (plasmonic crystals) exhibit a band structure with finite curvature (effective mass), in contrast to the linear and square-root dispersions of gated and ungated plasmons. These modes can be excited by synchronous gate-voltage pumping, avoiding the spatial nonuniformities of current-driven excitation. When the modulation drives the gated regions across threshold, the system enters a strongly nonlinear regime in which periodic modulation of the channel capacitance provides a parametric drive described by a generalized Mathieu equation. Depending on damping, this leads to either damped response or parametric instability. The resulting nonlinear dynamics generates a broad harmonic spectrum, enabling RF-to-THz frequency upconversion. Estimated drive conditions are compatible with existing millimeter-wave sources, including Schottky-diode multiplier chains and Gunn-diode oscillators.

Prediction of mass spectra using large chemical language models and verification of adaptability in data-scarce domains

Machine learning methods for predicting the electron ionization mass spectra from molecular structures have shown promise for environmental chemical identification, but their performance under domain-specific data scarcity remains poorly understood. We systematically compare a conventional multilayer perceptron model (NEIMS) with a Transformer-based chemical foundation model (MolFormer-XL) for the electron ionization mass spectrometry spectrum prediction under controlled few-shot conditions. Using fluorine-containing molecules as a broader proxy domain, including a PFAS-like subset, motivated by the practical challenge of detecting novel fluorinated contaminants with limited reference data, we vary the number of domain-specific training examples from 5 to 175 while maintaining fixed validation and test sets. Across all few-shot conditions and three of four evaluation metrics (weighted cosine similarity, intensity-weighted precision, and top-10 precision), MolFormer-XL consistently outperforms NEIMS, while intensity-weighted recall remains comparable between the two models. The largest performance gaps are observed in extreme data-scarcity regimes. These results demonstrate that MolFormer-XL, which combines pre-trained molecular representations with a Transformer-based architecture and learned SMILES embeddings, provides a promising approach for transfer under severe domain-specific data scarcity in environmental mass spectrometry.

Defect engineering via O-Se co-treatment enabled high-performance self-powered Au/O-Se MoS2/In photodetector

Self-powered photodetectors (SPPDs) are essential for energy-self-sufficient optical imaging and optical communication applications. However, the defects generated in two-dimensional transition metal dichalcogenides lead to Fermi-level pinning at metal–semiconductor interfaces and non-radiative recombination of carriers, thereby seriously degrading the performance of SPPDs. The traditional defect engineering predominantly relies on single-atom passivation strategies, which essentially target a single type of defect, making it difficult to suppress multiple defect states located at different energy levels. Herein, we demonstrate a sequential multi-atom cooperative defect repair strategy in MoS2, which simultaneously repairs multiple defect states associated with sulfur vacancies within a single material. As a result, the Au/O-Se MoS2/In photodetector exhibits a high responsivity of 0.21 A/W, together with an ultrafast response speed of 720 ns under zero bias voltage. The device achieves high-fidelity optical imaging and reliable optical communication under self-powered operation. This work establishes a universal strategy for defect control through multi-atom cooperative effects, providing an avenue for achieving high photoelectric conversion in next-generation optoelectronic devices.

Outside Front Cover: Rediscovering Sodium Ionophores as Selective Agents for Lithium Recognition and Extraction (Angew. Chem. Int. Ed. 32/2026)

Electrostatically confined charge transport in split-gated MoS2 device

As semiconductor scaling approaches the quantum limit, transport phenomena increasingly deviate from classical behavior, necessitating the development of electrostatically defined low-dimensional architectures. Here, we demonstrate one-dimensional (1D)-like charge transport in a gate-defined quantum point contact based on a hexagonal boron nitride (h-BN)-encapsulated few-layer molybdenum disulfide (MoS2) device at cryogenic temperatures. The device exhibits an electron mobility of ∼6600 cm2 V−1 s−1 at 4.2 K, reflecting minimized disorder and a pristine heterostructure interface. A global back-gate controls the carrier density and reduces contact resistance via electrostatic doping at the contacts, while a local top-gate tunes the channel potential. Bottom split gates define a laterally confined conduction channel that can be continuously tuned to pinch-off, enabling precise control of carrier confinement. The observed transport characteristics reveal a transition from two-dimensional to 1D-like transport. These results highlight the potential of multi-gate MoS2 heterostructures for gate-defined quantum devices.

Wet-spinning vanadium oxide-based coaxial fibers for the construction of zinc-ion batteries

Fiber-shaped aqueous zinc-ion batteries (FAZIBs) emerge as a promising energy storage device for future wearable electronics. Vanadium-based oxides possess high theoretical capacity, benefiting from their multiple oxidation states and versatile open-framework structures, yet its practical application is largely hindered by the poor electrical conductivity and cycling instability. Herein, we develop a core–sheath fiber as a cathode for FAZIBs via coaxial wet-spinning. The incorporation of reduced graphene oxide (rGO) significantly enhances electron transport in the V2O3 core, while the utilization of holey rGO (HrGO) as a sheath guarantees rapid ion diffusion at the same time renders further mechanical and electrical supports. The obtained V2O3/rGO@HrGO fiber exhibits a high volumetric capacity of 429 mAh cm−3 at 0.4 A cm−3 and still retains 275 mAh cm−3 at 4.0 A cm−3 with improved stability. This study provides an alternative option for the design of a high performance fiber cathode for future wearable aqueous ZIBs.

Toroidal quasi-dark supermodes in microwave dielectric metasurfaces

We report a class of dielectric metasurfaces that support quasi-dark microwave resonances with tailored toroidal and antitoroidal field profiles. The metasurfaces are realized using quadrumers of high-permittivity and low-loss ceramic disk resonators as elementary building blocks, assembled on laser-processed dielectric foam substrates. The physical origin and symmetry properties of the supported modes are elucidated through group-theoretical analysis and validated by eigenfrequency and full-wave finite-element simulations. Experimental measurements confirm the existence of quasi-dark resonances with suppressed radiation losses. Owing to its generic and scalable design strategy, this approach can be readily extended to a broad range of dielectric metasurfaces composed of ceramic Mie resonators. The demonstrated metasurfaces provide a versatile platform for low-profile and strongly resonant devices, e.g., for sensing or narrowband filtering.

Synergistic effect of waste sisal fiber-derived carbon and graphene oxide for performance enhancement of sulfur-based thermally regenerative batteries

Sulfur-based thermally regenerative batteries (STRBs) offer a promising approach for low-grade waste heat recovery. To enhance their power output, we develop a sulfur electrode using a composite of sisal fiber-derived activated carbon (SFAC) with a porous structure and graphene oxide (GO) from waste biomass. The SFAC framework enhances the electrochemically active surface area while simultaneously reducing electron transport resistance, thereby boosting overall electrode performance. The incorporation of GO improves hydrophilicity and ion transport. The synergy between the two components significantly boosts power density and cycling stability. The STRB with the SFAC-GO@S electrode achieves a maximum power density of 56.9 W m−2, which is 57.6% higher than that of a bare carbon cloth-based sulfur electrode. The GO encapsulating effect on sulfur particles within SFAC pores yields a capacity retention of 89.6% after 30 cycles. An optimal GO concentration of 1.5 mg ml−1 gives the highest power density of 70.7 W m−2. Excessive GO causes agglomeration and blocks ion transport, degrading performance.

High-performance phototransistors based on heterojunctions of organic semiconductors and 2D perovskite single crystals

Two-dimensional (2D) organic–inorganic hybrid perovskites are promising candidates for optoelectronic applications owing to their excellent optoelectronic properties and enhanced stability compared to their three-dimensional counterparts. However, the optoelectronic performance of 2D perovskite single crystals is often constrained by low charge transport efficiency. Herein, we fabricated a (PEA)2PbI4/PDVT-10 heterojunction and corresponding phototransistor by transferring a mechanically exfoliated (PEA)2PbI4 single crystal onto a PDVT-10 film. This design strategically combines the exceptional light-harvesting ability of the perovskite with the high charge carrier mobility and gate tunability of the organic semiconductor. As a result, the concerted action of the photoconductive and field effects within the heterojunction yields outstanding photodetection metrics. Compared to the PDVT-10 device, the (PEA)2PbI4/PDVT-10 device shows a twofold improvement in photosensitivity (Ilight/Idark ∼ 1.1 × 103 @ 64 mW cm−2), a nearly three-order-of-magnitude increase in photocurrent, and a 32-fold higher responsivity (0.65 A W−1, @ 0.01 mW cm−2). This study provides a viable strategy for integrating the superior properties of perovskite single crystals and organic semiconductors to fabricate high-performance photodetectors.

A Study to Assess Risk Stratification by Using Child-Pugh Score, Rate of Admission and Management Strategies of Inpatients with Alcoholic Liver Disease

Objective: To assess risk stratification using the Child-Pugh scoring system, evaluate hospital admission profiles, and audit real-world pharmacological management in hospitalized patients with Alcoholic Liver Disease (ALD). Methodology: A six-month prospective observational study included 123 confirmed ALD inpatients admitted to the General Medicine Department of ESIC Medical College & Model Hospital, Bengaluru. Demographic characteristics, alcohol consumption history, clinical features, laboratory parameters, and treatment patterns were recorded. Statistical analyses included Chi-square test, one-way ANOVA, Kruskal-Walli’s test, Spearman's rank correlation, and Odds Ratio (OR) analysis. Results: The mean age was 47.30 ± 9.07 years, with 95.12% males. Most patients were classified as Child-Pugh Class C (58.54%), followed by Class B (29.26%) and Class A (12.20%). Alcohol consumption for >10 years was significantly associated with advanced liver disease (p = 0.0096; OR = 2.12). Disease severity was significantly associated with portal hypertension (79.67%, p < 0.001), ascites (65.85%, p < 0.001), hepatic encephalopathy (31.71%, p = 0.00017), hepatorenal syndrome (18.70%, p = 0.0222), coagulopathy (22.76%, p = 0.0216), and esophageal varices (49.60%, p = 0.0437). Laboratory abnormalities, including reduced albumin and elevated bilirubin, INR, AST, ALT, and ALP, correlated with increasing severity (p < 0.01). Although hospital stay did not differ significantly across Child-Pugh classes (p = 0.269), Class C patients had a twofold higher readmission risk (OR = 2.02). Lactulose, rifaximin, ursodeoxycholic acid, furosemide, and spironolactone were the most frequently prescribed drugs, while corticosteroid use was limited (3.25%). Conclusion: The Child-Pugh score is an effective bedside tool for predicting disease severity, complications, and readmission risk in ALD. Variations from evidence-based treatment, particularly excessive ursodeoxycholic acid use and limited corticosteroid prescribing, highlight the need for improved guideline-directed management.

High quantum-efficiency InGaAs/InP photodiodes heterogeneously integrated on SiN waveguides

The integration of photodiodes with optical waveguides is increasingly important for photonic integrated circuit development. We report modified uni-traveling-carrier photodiodes heterogeneously integrated onto Si3N4 optical waveguides, achieving quantum efficiencies up to 91% at 1550 nm. The combination of high quantum efficiencies and ultra-low dark currents yields high signal-to-noise ratios over a broad range of optical signal powers.

Deciphering the Insulin Link: Exploring Metabolic Interplay in Polycystic Ovary Syndrome

One of the most prevalent endocrine illnesses in women, polycystic ovarian syndrome (PCOS), has a prevalence of 2.2% to 26% in India. Menstrual irregularities, hirsutism (excessive hair growth), acne, weight issues, and infertility are challenges that PCOS sufferers face. A significant player in the world of PCOS is the emergence of persistent, mild inflammation. Elevated blood sugar levels appear to trigger oxidative stress, inciting an abnormal response from specialized cells (mononuclear cells or MNCs) in females affected by PCOS, even though these cells typically don't depend on fat for fuel. This phenomenon becomes particularly significant since MNC-derived macrophages stand as primary culprits behind cytokine production in large fat tissues, further exacerbating the release of inflammatory substances from fat cells. In essence, the evidence underscores the notable perils posed by insulin resistance, particularly in the context of PCOS-afflicted individuals who are also battling obesity. The insights gleaned from this specific study underscore that those conforming to the classic PCOS profile often exhibit obesity, elevated insulin levels, and insulin resistance, irrespective of potential differences in Body Mass Index (BMI) compared to other PCOS phenotypes. This body of information conclusively underscores that insulin resistance takes precedence as the foremost pathological hallmark within the PCOS population.

Constraints on atomistic disorder for scalable electron spin shuttling

Electron spin shuttling—the gate-controlled, coherent transport of electrons between qubit registers—increases qubit connectivity and enables efficient quantum-error-correction schemes. It is emerging as a key enabler of scalable silicon spin-qubit quantum computing. As an electron travels over micrometers, it encounters angstrom-scale disorder, causing fluctuations in its confinement potential, valley splitting, and valley phase. These lead to leakage into the valley-excited state, limiting high-fidelity shuttling speeds. Accurate predictions of shuttling fidelities thus require modeling tools that link atomistic and mesoscopic physics. We develop a multiscale simulation workflow to quantify these effects in the experimentally realized Si/SiGe “QuBus” conveyor-belt architecture. First, we resolve the time-dependent, gate-controlled device electrostatics by solving the Poisson equation using the finite-element method. Second, we construct conveyor-belt atomic structures with realistic atomistic disorder (random alloying and interface roughness); we resolve strain atomistically using the Keating valence force-field model. Third, we perform position-tracked atomistic tight-binding simulations of the shuttled electrons to obtain their time-dependent valley splittings and phases. Finally, these time traces parametrize a time-dependent Schrödinger equation, which we solve to predict valley dynamics. We find that interface roughness strongly suppresses shuttling fidelities, with a sharp anomaly near the atomic-layer scale. Overall, our predictions set practical, quantitative guidelines to realize scalable, high-fidelity shuttling in silicon spin-qubit architectures.

Internal-loss-limited 5.5% wall-plug efficiency in index-guided AlGaN UV-B laser diodes with polarization-doped cladding layers

This study identifies the dominant factor governing wall-plug efficiency (WPE) in AlGaN-based UV-B laser diodes. While previous studies have mainly focused on optical confinement, the limiting mechanism has remained unclear. Here, we investigate index-guided ridge waveguide laser diodes and systematically analyze the relationship between internal optical loss (αi) and device performance. Index-guided operation is confirmed by effective index simulations and near-field measurements. We find that device performance is governed primarily by αi rather than optical confinement. By minimizing αi, the threshold current is reduced, and the slope efficiency is improved, leading to a maximum WPE of 5.5% in an uncoated device. These results reveal that reducing αi, rather than enhancing optical confinement, is the key design principle for improving WPE in AlGaN-based UV-B laser diodes.

Stable asymmetric magnetization reversal in epitaxial Co(001)/CoO(001) bilayer

The exchange bias (EB) in ferromagnetic/antiferromagnetic (FM/AFM) bilayer systems causes a shift in the magnetic hysteresis curve after field cooling through the Néel temperature of the AFM. In some cases, this shift is accompanied by an asymmetry between the ascending and descending branches. In the past, this asymmetric magnetization reversal has been studied in different bilayer systems, including polycrystalline Co/CoO thin films. Here, we investigate the asymmetric magnetization reversal in an epitaxial fcc-Co(001)/CoO(001) thin film grown on MgO(001) by molecular beam epitaxy at varying temperatures up to room temperature after field cooling along the easy and the hard axes. Room temperature measurements of the longitudinal and transverse magneto-optic Kerr effect show different magnetization reversal processes via stable intermediate states for different angles between the external magnetic field and the magnetic easy axes. Once the sample is cooled below the blocking temperature, a pronounced asymmetric magnetization reversal can be observed. We show that in contrast to polycrystalline bilayers, the loop asymmetry stays constant after multiple training cycles and that the magnitude of the asymmetry is directly correlated with the magnitude of the EB.

Separating intrinsic and domain-mediated anomalous Hall conductivity in Co3Sn2S2 via contact engineering

Separating the momentum-space intrinsic Berry-curvature contribution to the anomalous Hall conductivity (AHC) from domain-mediated and extrinsic contributions in bulk ferromagnetic Weyl semimetals remains a central challenge. We address this via contact engineering in a ∼670 μm thick Co3Sn2S2 single crystal, where deep Ohmic contacts promote depth-distributed current flow without perturbing the bulk. Above ∼0.3 T, a single- or few-domain state exposes the intrinsic Berry-curvature response, with Callen–Callen scaling Ku/Ku(0)=[M/M(0)]n=2.258 holding below 120 K. Above 120 K, domain multiplication weakens the exchange splitting and magnetocrystalline anisotropy Ku, driving a sharp σxy crossover near 125 K. In low-field zero-field-cooled multidomain states, real-space Berry curvature and moderate extrinsic contributions sustain the Hall response up to ∼140 K. These results establish contact engineering as a noninvasive route for cleanly separating intrinsic from domain-mediated AHC in thick Weyl semimetal crystals.

<i>In situ</i> electric field-assisted curing enables low dielectric constant and loss through polarization suppression

Low-dielectric materials are crucial for reducing RC delay in high-density integrated circuits. Here, we report an electric field-assisted in situ curing strategy for dicyclopentadiene-based epoxy films to achieve reduced dielectric constant (εr) and loss tangent (tan δ). The applied electric field modulates local chain conformations and promotes crystalline microdomain formation, effectively suppressing dipolar polarization. Under an electric field of 6 kV mm−1, εr and tan δ are reduced by up to 8.5% and 78.9% at 102 Hz, and by 7.8% and 7.1% at 5 GHz, respectively. This work provides a unique route for tuning dielectric properties via electric field-induced structural control, offering potential for advanced electronic packaging applications.

Outside Back Cover: Upcycling Water Pollutants Into Long‐Chain Polymers via Synergistic Interfacial Dechlorination and Organic Radical Stabilization (Angew. Chem. Int. Ed. 32/2026)

Homoepitaxial GaN-on-GaN trench MOSFETs with 438 MW/cm2 figure of merit and improved gate reliability

In this paper, we report enhanced high-voltage blocking capability and improved gate dielectric reliability in vertical GaN-on-GaN trench metal–oxide–semiconductor field-effect transistors (MOSFETs) through fabrication process optimization. A thick bottom dielectric (TBD) is introduced at the trench bottom to suppress the peak electric fields in both the gate dielectric and the GaN layer, resulting in a substantial improvement in breakdown voltage (VBR). The fabricated fully vertical device exhibits a low specific on-resistance (RON,sp) of 1.46 mΩ cm2, a maximum drain current density (ID,max) of 2.5 kA/cm2, an on/off current ratio (ION/IOFF) of 1010, and a VBR of 800 V, thereby achieving a competitive Baliga's figure of merit of 438 MW/cm2. In addition, due to the increased gate-drain distance, the output capacitance (COSS) of the device is reduced by more than 14%, which is beneficial for reducing the switching loss. Reliability measurements, including positive bias threshold voltage instability and step-stress gate breakdown tests, indicate that the TBD improves the voltage tolerance of the gate dielectric without introducing additional instability at the channel interface. Interface trap density (Dit) at the trench sidewall is characterized by the conductance method, which is found to be 1 × 1012 cm−2 eV−1. Furthermore, trap-assisted tunneling analysis of the gate leakage extracts a trap level of ∼1.3 eV within the Al2O3 gate dielectric, which accounts for the wear-out behavior under step-stress breakdown. This work demonstrates the effectiveness of the TBD technique for the development of high-performance and reliable GaN trench MOSFETs.

Zulema Fernández