Browse Articles

Strain-induced polarization of AlN/GaN heterointerfaces enabling ultra-high 2DEG densities

The strong polarization fields present at the AlN/GaN heterointerface make them an attractive candidate for the development of high electron mobility transistors (HEMTs) with high current densities. In this work, we report exceptionally high two-dimensional electron gas (2DEG) density in AlN/GaN heterostructures grown by plasma-assisted molecular beam epitaxy. The sample with a 9 nm AlN barrier, near the onset of relaxation, yields a maximum 2DEG density of ∼1.3 × 1014 cm−2, more than 2× larger than previously reported values, while the fully strained 6 nm barrier exhibits ∼7.8 × 1013 cm−2 with superior crystalline quality. Additionally, the sheet resistance values reported in this work are below 200 Ω/□ at 2DEG densities approaching 1014 cm−2. These results highlight the critical role of strain–polarization coupling in achieving extreme carrier confinement, establishing benchmarks for III-nitride HEMTs and future wide-bandgap electronics.

Slc22a17 governs postnatal neurogenesis by maintaining the iron homeostasis in hippocampus

Modulating Chern number of spin- <i>J</i> model with the superconducting qudit

Superconducting circuits, owing to their high tunability, provide a controllable platform for studying topological systems that are difficult to manipulate in natural materials. The topological properties of spin particles have been extensively studied and remain of significant interest. Previous studies have primarily focused on spin-1/2 models. In this article, we explore the topological properties of the spin-J system by measuring the Chern number, which characterizes nontrivial phases and topological transitions. We experimentally demonstrate topological transitions in high-spin systems. Furthermore, the feasibility of the adiabatic evolution scheme was examined in our study. Experimental results proved that our scheme can be applied to explore topological phenomenon in higher-dimensional systems.

Skin-conformal MHz-speed organic photodetectors for angle-free and long-range near-infrared communication

In-plane anomalous Hall effect and unconventional spin-to-charge conversion in Co/PtCoOx heterostructures

We demonstrate in-plane anomalous Hall effect (iAHE) and unconventional spin-to-charge conversion in in-plane Co/PtCoOx heterostructures grown by magnetron sputtering. The temperature-dependent measurements show a strong iAHE signal persisting up to 400 K. In the conventional AHE, transverse voltage is observed when a magnetic field is swept along the out-of-plane direction, whereas in our case, transverse voltage is obtained when a field is swept along the in-plane direction transverse to the current flow. The out-of-plane magnetization measurements show non-negligible out-of-plane magnetization, which causes the iAHE in our Co/PtCoOx stack structure. This out-of-plane remnant magnetization is attributed to the coupling between CoO moments and in-plane Co moments. Our findings expand the understanding of iAHE in ferromagnet/spin–orbit coupled heterostructures. Both the conventional and unconventional spin-to-charge conversions have also been observed at room temperature. The unconventional spin-to-charge conversion figure of merit is three times larger than the conventional spin-to-charge conversion.

Saffold virus exploits integrin αvβ8 and sulfated glycosaminoglycans as cooperative attachment receptors for infection

Abstract Saffold virus (SAFV), a member of the species Cardiovirus saffoldi within the Picornaviridae family, causes acute respiratory and gastrointestinal illnesses as well as hand, foot, and mouth disease. It is also suspected to be associated with neuronal disorders, such as encephalitis and meningitis, in severe cases. Despite its clinical significance, the virus-host interactions underlying SAFV pathogenicity remain largely unknown. Using a genome-wide CRISPR-Cas9 knockout screen, we identify the following receptors for SAFV infection: sulfated glycosaminoglycans (GAGs) and integrin αVβ8. Single knockouts of SLC35B2 , an essential gene for sulfated GAG synthesis, or the integrin genes ITGAV or ITGB8 partially reduce SAFV-3 and SAFV-2 susceptibility in HeLa cells, and a double knockout confers complete resistance. Furthermore, we demonstrate that SAFV-3 virions bind directly to sulfated GAGs and integrin αVβ8. Based on these findings, we propose a model of SAFV infection in which sulfated GAGs and integrin αVβ8 act through dual and cooperative pathways to facilitate viral entry.

Tri-terminal IGZO optoelectronic synapse with photoelectric co-modulation for neuromorphic computing

Optoelectronic synaptic devices show great promise for neuromorphic computing (NC), offering high-speed and energy-efficient information processing. This study explores the potential of indium gallium zinc oxide (IGZO) based optoelectronic synapses for applications in neuromorphic computing. A systematic analysis of excitatory postsynaptic currents and inhibitory postsynaptic currents was conducted, examining various optical parameters and electrical parameters, which integrates short-term memory and long-term memory mechanisms and highlights the device's capabilities for information storage and learning. The device mimics biological synaptic plasticity, as demonstrated by experimental data. An evaluation of image recognition on the Fashion-MNIST dataset, using a confusion matrix, resulted in a recognition rate of approximately 93% after 100 training epochs. This indicates the effectiveness of pattern recognition, showcasing the potential of IGZO optoelectronic synapses for high-precision neuromorphic computing.

Development of a replication-defective mpox virus platform for fundamental and therapeutic research

Geometric symmetry breaking of current distribution enables field-free programmable spin logic in T-shaped architecture

Achieving fully electrical and easily integrated programmable spin logic within a single device using spin–orbit torque (SOT)-driven perpendicular magnetization switching (PMS) remains a key challenge for realizing scalable and energy-efficient spin logic-in-memory computing. Here, we demonstrate controllable field-free SOT-driven PMS by the geometric asymmetry of current distribution in a “T-shaped” Pt/CoPt architecture. Deterministic clockwise/counterclockwise PMS is observed when applying current pulses along the left/right arms of the T-architecture, which has been attributed to the combined effect of geometrically curved current channel-induced Oersted field and inhomogeneous spatial distribution of spin currents. Furthermore, by implementing a three-step sequential pulsing scheme that precisely controls channel selection, an initial control current pulse, and two subsequent control pulses, we demonstrate the complete set of 16 Boolean logic functions within a single device. This simple material-agnostic and integration-friendly approach provides a pathway for developing fully electrical controllable SOT-based spin logic and in-memory computing devices.

Spatial patterning of the epigenome during vertebrate gastrulation

Influence of Bi surfactant on tetrahedral N interstitial formation and optoelectronic properties of dilute GaAsN alloys

Dilute nitride semiconductor alloys are attractive for near- to mid-IR optoelectronic applications but their widespread implementation is hindered by efficiency-limiting non-substitutional N incorporation. Although epitaxy in the presence of surfactants has been reported to increase photoluminescence (PL) emission intensity, the impact of surfactants on N incorporation mechanisms and the resulting optoelectronic properties remains unknown. In this work, we examine the influence of a Bi surfactant on non-substitutional N incorporation and the optoelectronic properties of dilute GaAs1−xNx alloy films. For GaAs1−xNx alloy films grown with a Bi surfactant, tetrahedral N interstitial (Ntetra) formation is suppressed while the near-band edge PL emission intensity is increased, deep-level PL emission intensity is decreased, and broadening of the photoreflectance resonance is reduced. We discuss the role of the Bi surfactant-induced surface reconstruction transformation on the suppression of Ntetra incorporation, as well as its impact on key optoelectronic properties that are applicable to a variety of highly mismatched alloys.

Convergent causal mapping unravels distinct frontal networks for visuospatial selective attention

Abstract Orienting visuospatial attention towards relevant stimuli is vital for effective environmental interactions. Current attentional control models rely on functional neuroimaging, which is correlational, and lesion studies in stroke patients, affected by localization bias. Studying patients undergoing awake neurosurgery for brain tumour resection offers a unique chance to overcome these limitations and possibly enhance current neurofunctional models. We combined Lesion-Symptom-Mapping (LSM) in 163 brain tumour patients and Direct Electrical Stimulation (DES) in 47 patients during awake neurosurgery to unveil the network causally associated with visuospatial exploratory/selective attention. LSM and DES convergently identified a right dorsomedial frontal region linked to visuospatial neglect, potentially functioning as a pre-oculomotor hub for contralateral attentional deployment. Moreover, stimulation of right ventrolateral white matter was associated with visuospatial errors in both hemifields. Finally, we provided a tool that effectively detects and preserves frontal connectivity for visuospatial exploratory/selective attention in neurosurgical settings.

Revealing phonon signature of dislocations in silicon carbide using machine-learning interatomic potential

Defects are the main performance killer in silicon carbide (SiC) power devices. Among various defect types, dislocations are particularly important, as they affect device reliability. However, first-principles modeling of dislocations is computationally challenging due to their complex, extended structure and topological nature. To overcome this difficulty, we develop a neuroevolution potential (NEP) to enable accurate and large-scale lattice dynamics simulations for defect-containing SiC. To circumvent the difficulty of direct dislocation calculation, the NEP is trained on a first-principles dataset generated by iteratively incorporating various point defects, line defects, and surface structures that are computationally tractable. The resulting NEP reproduces phonon spectra in crystalline and dislocation-containing SiC, indicating its transferability. With this potential, we analyze the phonon characteristics around dislocations in 4H-SiC. Our results reveal localized vibrational modes around dislocation cores, and phonon frequency shifts away from the cores due to dislocation-induced strain fields. This work may facilitate the identification of dislocation phonon signatures and delivers a machine-learning potential that overcomes the computational limitations for large-scale SiC defect simulations.

Medicago super-pangenome reveals adaptive advantages and evolutionary constraints in autotetraploid alfalfa

Improving efficiency and water–oxygen barrier of perovskite solar cells through phenylalanine additives

Perovskite solar cells (PSCs) show strong potential in the photovoltaic field, but their limited material stability hinders industrial-scale application. Major challenges include degradation of the perovskite structure caused by water and oxygen, as well as uncontrolled crystallization that leads to defects and non-radiative recombination, reducing the device's power conversion efficiency (PCE). This work introduces phenylalanine (PHE) into the precursor solution. The large-sized benzene ring of PHE enhances the film's resistance to water and oxygen. In addition, the water–oxygen adsorption energy of perovskite materials is calculated based on density functional theory simulation, and the steric effects of PHE is quantified. Meanwhile, the Lewis basicity of PHE promotes directional crystallization and defect passivation of the perovskite layer. The optimized PSCs achieve a PCE of 21.49%. The T90 lifetime reaches 1008 h at room temperature and humidity (25 °C, 40% RH), and exceeds 1150 h in a desiccator (25 °C, 10% RH).

Unequal mitochondrial segregation promotes asymmetric fates during neurogenesis

Abstract Asymmetric cell division plays a critical role during vertebrate neurogenesis by generating neuronal cells while maintaining a pool of progenitors. It relies on unequal distribution of cell fate determinants during progenitor division. Here, we use live imaging in the chick embryonic neuroepithelium to demonstrate that mitochondria behave as asymmetric fate determinants during mitosis. We show that the frequency of unequal distribution of mitochondria increases in parallel with the rate of asymmetric divisions during development. Furthermore, fate tracking experiments reveals that following progenitor division, a cell inheriting fewer mitochondria than its sister consistently differentiates into a neuron. We set up a chemogenetic approach to experimentally displace mitochondria specifically during mitosis to force their unequal inheritance and find that this drives premature neuronal differentiation. In this work, we establish a direct causal relationship between unequal mitochondrial inheritance and the asymmetric fate of sister cells in vivo, revealing a pivotal mechanism for neurogenesis.

Spin-splitting-torque-driven field-free perpendicular magnetization switching in RuO2/synthetic antiferromagnet heterostructures for spintronic convolutional neural networks

With the growing demand for low-power and high-speed spintronic devices, the development of advanced material systems with efficient spin control capabilities has emerged as a central focus in spintronics research. Here, we propose a fully antiferromagnetic device architecture based on a magnetically compensated RuO2/synthetic antiferromagnet heterostructure, achieving fully electrical writing and reading functionalities. This design, characterized by its negligible stray field and deterministic field-free switching, is inherently suitable for large-scale neuromorphic integration. In a proof-of-concept demonstration, we showcase the implementation of an all-spintronic convolutional neural network using this architecture, achieving a high recognition accuracy of 98.7% on the handwritten digit classification task.

Mitochondrial RNA cytosolic leakage drives the SASP

Abstract Senescent cells secrete proinflammatory factors known as the senescence-associated secretory phenotype (SASP), contributing to tissue dysfunction and aging. Mitochondrial dysfunction is a key feature of senescence, influencing SASP via mitochondrial DNA (mtDNA) release and cGAS/STING pathway activation. Here, we demonstrate that mitochondrial RNA (mtRNA) also accumulates in the cytosol of senescent cells, activating RNA sensors RIG-I and MDA5, leading to MAVS aggregation and SASP induction. Inhibition of these RNA sensors significantly reduces SASP factors. Furthermore, BAX and BAK play a key role in mtRNA leakage during senescence, and their deletion diminishes SASP expression in vitro and in a mouse model of Metabolic Dysfunction-Associated Steatohepatitis (MASH). These findings highlight mtRNA’s role in SASP regulation and its potential as a therapeutic target for mitigating age-related inflammation.

Optimization of electric field distribution for AlGaN/GaN MIS-HEMT with thick i-GaN cap layer

The significant optimization of electric field distribution for AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) with a thick i-GaN cap layer is reported. The thick i-GaN cap layer is introduced to generate two-dimensional hole gas (2DHG), thereby reducing the electron concentration in the two-dimensional electron gas (2DEG) layer under off-state, in contrast to the high electron concentration in the 2DEG layer under off-state for the MIS-HEMT with a p-type or insulating passivation layer. Due to the low electron concentration in the 2DEG layer and the introduction of the thick i-GaN cap layer, a wide depletion region forms in this cap layer just close to the drain electrode under off-state, resulting in a low electric field intensity both in the whole access region and in the region close to the gate. Thus, the adverse effect induced by the high electric field strength under off-state, such as the large dynamic on-resistance (Ron), is significantly mitigated.

Advanced biomimetic nanofiltration membranes for lithium recovery with anti-janus charge structure