Browse Articles

The critical excitation intensity for expansion of single Shockley stacking fault in 4H-silicon carbide: Theoretical study

Modeling the single Shockley stacking fault (1SSF) in 4H-silicon carbide as a classical well built in the bottom of the conduction band, technical computer-aided design simulations were conducted rigorously incorporating carrier recombination at the 1SSF. The experimentally observed temperature dependences of the critical photoexcitation intensity for 1SSF expansion can be reproduced only if the radiative recombination coefficient in the 1SSF at room temperature is enhanced by a factor of about 103 times larger than the value in the matrix. The primary cause of energy reduction Δγ due to the presence of the 1SSF is such enhanced carrier recombination in the 1SSF. However, the main contribution to Δγ arises from the reduction in electronic energy in the perfect matrix surrounding the 1SSF over the range of minority carrier diffusion length. This provides another reason why 1SSF expansion is suppressed by the reduction in carrier lifetime. The cause of the apparent discrepancy of experimentally evaluated γ1SSF, the formation energy of the 1SSF in thermo-equilibrium, between n- and p-type samples obtained in mechanical stressing experiments can be attributed to the nonlinear dependence of Δγ on the electron–hole generation rate in the low-injection regime and the inherent difference in the degree of the nonlinearity between n- and p-type samples. The value of γ1SSF is considered to be closer to 7.9 ± 1.3 mJ/m2, which is experimentally deduced in p-type samples.

Enhanced water desalination via PVDF-chabazite mixed matrix membranes in vacuum membrane distillation

Oxidation-reconstructed Li+ transport enables high-tap-density single-crystal regeneration of spent LiNi0.5Co0.2Mn0.3O2 positive electrodes

The critical excitation intensity for expansion of single Shockley stacking fault in 4H-silicon carbide: Experimental study

Mechanical stressing experiments devised to evaluate the formation energy of a single Shockley stacking fault (1SSF) γ1SSF have been conducted with the use of photoluminescence imaging of partial dislocations bounding 1SSFs in various 4H-SiC epilayers. Elaborate care was taken to avoid the blocking effect of point obstacles on the glide motion of partial dislocations that enables expansion and contraction of the 1SSFs. Analysis of the experimental results appears to show apparently different values of γ1SSF between n-type and p-type samples. Conversely, the critical ultraviolet light intensity that demarcates 1SSF expansion and contraction showed a similar temperature dependence for n-type and p-type samples.

High-resolution cryo-EM structures of small protein–ligand complexes near the theoretical size limit

Physics-guided deep learning with adversarial domain adaptation: Applications to STM image denoising

Image denoising is essential in materials characterization, particularly for recovering fine structural details in scanning tunneling microscopy (STM) images. While supervised denoising approaches have shown strong performance, they typically rely on large datasets of paired noisy and clean images, which are often unavailable in experimental settings. Unsupervised methods, though not requiring paired data, often rely on a collection of unpaired clean images for training—resources that are frequently unavailable in real-world STM laboratory environments. In this work, we propose PDA-Net, a physics-guided deep learning framework with adversarial domain adaptation for unsupervised STM image denoising. PDA-Net leverages a physics-based simulator to generate synthetic STM images for the surface of copper single crystals, i.e., Cu(111), serving as a proxy for the clean ground truth. Built upon a generative adversarial network architecture, the framework integrates cycle-consistency and domain adversarial modules to bridge the gap between simulated and real experimental domains in the absence of paired data. Additionally, feature alignment and weight-sharing strategies are employed to enhance knowledge transfer between domains. Experimental results demonstrate that PDA-Net significantly improves STM image quality, enabling more accurate interpretation of quantum material properties and facilitating accelerated scientific discovery.

Carbon monoxide oxidation expands the known metabolic capacity in anaerobic methanotrophic consortia

Theoretical investigation of thermionic electron emission from semiconductors and insulators and mean escape probability of internal secondary electrons

From the definitions of parameters of thermionic electron emission, theories of insulators and semiconductors (IS) and field emission, and those of the escape of electron-induced internal secondary electrons (EIISE), the formulas for j, G, EAve, and B of IS and semiconductors with high-density surface energy states (SHS) were deduced, respectively. Here, j, G, and EAve denote the current density, spectrum, and average energy of hot electrons, respectively; B is the average probability that a hot electron escapes into vacuum upon reaching the surface. The deduced formulas were analyzed and compared with existing results. It is concluded that the deduced formulas for j of IS and SHS are theoretically correct, and that the formulas for G, EAve, and B derived here can express those quantities for IS and SHS, respectively. From the definition of Bs and the fact that, when the absolute temperature in the formula for G is taken as a given value, the deduced G of IS can express the spectra of secondary electrons from IS, the formula for Bs and a more accurate method for calculating Bs were deduced and presented, respectively. Here, Bs denotes the mean escape probability of EIISE reaching the emission surface of IS. The method for calculating ΔQ using the formula for j of SHS derived here was presented, where ΔQ is the quantity of band bending due to high-density surface energy states of semiconductors. The two presented methods were analyzed, and it is concluded that they are correct.

Carbon monoxide metabolism in freshwater anaerobic methanotrophic archaea

Abstract Anaerobic methanotrophic archaea mitigate methane emissions in anoxic environments as key members of the biological methane filter. Despite their ecological significance, physiology of anaerobic methanotrophs remains poorly understood. Here, we demonstrate that the freshwater methanotroph ‘ Candidatus Methanoperedens BLZ2’ prefers carbon monoxide (CO) over methane as an electron donor. Without respiratory nitrate, CO oxidation led to acetogenesis and methanogenesis with rates comparable to methane oxidation with nitrate. The circularized genome of ‘ Ca . M. BLZ2’ encodes six Ni-dependent carbon monoxide dehydrogenases (CODHs ) , three of which were highly expressed. Furthermore, we identified a 156-kbp mobile genetic element carrying central metabolic gene clusters, including two additional, highly expressed CODHs. CODH genes were widespread in Methanoperedenaceae and showed diverse evolutionary affiliations, including Methanocomedenaceae anaerobic methanotrophs and bacterial lineages. These findings highlight CO metabolism and genome plasticity in anaerobic methanotrophs challenging their classification as obligate methanotrophs and their ecological role in anoxic carbon cycling.

Erratum: “The optical signature of few-layer ReSe2” [J. Appl. Phys. <b>128</b> , 044302 (2020)]

Strain‒induced spin regulation of stepped Co(111) for boosting peracetic acid magnetocatalysis

Realization of a ferromagnetic insulator in the La0.7Sr0.3MnO3/LaCoO3 superlattice

Artificially structured oxide superlattices provide a fertile ground for engineering electronic states. In this work, we report the synthesis of high-quality La0.7Sr0.3MnO3/LaCoO3 superlattices, which exhibit insulating ferromagnetism with a Curie temperature (TC) elevated to 230 K. Unlike conventional La0.7Sr0.3MnO3/SrTiO3 counterparts, the magnetic ordering in this system is driven by a distinct interfacial mechanism. By systematically varying the layer thickness, we observe a clear correlation between the ferromagnetic coupling and the interface density. Spectroscopic evidence from x-ray absorption identifies a valence shift toward the Co2+ state, indicative of Mn-to-Co charge transfer. This electronic reconstruction activates a strong superexchange pathway between Mn4+ and Co2+, consistent with Goodenough–Kanamori–Anderson rules. Furthermore, element-specific magnetic circular dichroism reveals robust magnetic moments on both sublattices, persisting well above 200 K. Our findings demonstrate that interfacial charge redistribution in superlattices is a viable route to overcome the low-TC limitations of ferromagnetic insulators.

Convergent and selective representations of pain, appetitive processes, aversive processes, and cognitive control in the insula

Abstract Brain regions that integrate multiple types of information (“convergence zones”) are crucial for the brain to generate coherent experiences and behaviors. The insula, known for its functional diversity, has been hypothesized as a key convergence hub, yet empirical evidence remains incomplete. To address this gap, we analyzed functional convergence across four domains—pain, non-somatic appetitive processes, non-somatic aversive processes, and cognitive control—in a Bayesian mega-analysis of fMRI data ( n  = 540, 36 study contrasts). Bayes Factor analyses identified both multi-domain convergent and single-domain selective zones, validated with independent datasets ( n  = 608). Results revealed a hierarchical architecture, with a multi-domain convergence zone in bilateral dorsal anterior insula surrounded by progressively converging zones. Functional decoding and coactivation analyses further support the insula’s role as a convergence hub, while cytoarchitectonic and neurotransmitter profiling characterize the potential neuroanatomical basis of these zones. Together, the findings demonstrate a structured functional topography in the insula that bridges specialized and convergent processing, providing a potential neural basis for combining diverse information streams into unified experiences.

Impact of geometric parameters on the electrical performances of pseudo-vertical GaN-on-Si p–n diodes with avalanche capability via selective epitaxy

In this study, we present a GaN-on-Si pseudo-vertical p–n diode fabricated using selective area growth (SAG). The device achieved a high current density of 1.5 kA cm−2 and a low specific on-resistance (Ron,sp) of 3.3 mΩ cm2. A very high on/off current ratio (Ion/Ioff) of 1012 was also recorded. Notably, for the first-time using SAG, uniform avalanche breakdown behavior of 850 V was demonstrated through temperature-dependent reverse bias measurements, corresponding to a Baliga figure of merit of 0.2 GW cm−2. These results emphasize the advantages of localized epitaxy in achieving high-quality p–n junctions on Si substrates, paving the way for scalable, high-performance GaN power devices monolithically integrated with Si technology. To evaluate the influence of geometric parameters on epitaxial quality and device performance, the mesa spacing was systematically varied while keeping the diameter fixed. Optimal results were obtained with 5–15 μm spacing, offering the best trade-off between forward conduction efficiency and reverse blocking robustness. This comprehensive investigation underscores the importance of geometric optimization and localized epitaxy in advancing high-performance GaN-on-Si p–n diodes for next-generation power applications.

Quantitative stable isotope probing (qSIP)-informed metagenomics identifies viruses infecting chemoautotrophs

Phase-field study on tip-force-induced metal–insulator transition and nucleation dynamics in VO2 thin films

Despite significant progress being made in research on the mechanism and control of vanadium dioxide (VO2) phase transition, localized metal-to-insulator transition (MIT) and monoclinic VO2 (M) nucleation evolution in rutile VO2 (R) thin films under the application of tip force remain unclear, particularly on how these processes depend on the film orientation and how the tip force selects M-phase variants. Here, based on phase-field simulations and theoretical analysis, the localized MIT and the domain nucleation evolution behavior in [001]R and [110]R oriented VO2 thin films under tip-force loading are revealed. Results show that under the conditions of identical film thickness and tip-force application, the [001]R-oriented thin films are more prone to inducing localized MIT and typically form a quatrefoil morphology of domain nuclei mixed with M1/M2 phase variants. In contrast, MIT nuclei in [110]R-oriented thin films have smaller sizes and typically form an olive-shaped along the [001]R axis. Moreover, the occasional formation of antiphase boundaries in the same M-phase variant during MIT is found to significantly affect the morphology of domain nuclei. Our results reflect a strong impact of the film orientation on the tip-force-induced MIT of VO2 thin films, which is essentially due to the distinct eigenstrain characteristics of M-phase variants in the [001]R and [110]R coordinate systems, which modulate the degeneracy of M-phase variants and their selection during MIT. The work provides new insights into the tip-force-induced MIT and nucleation dynamics in VO2 thin films, and it is instructive for engineering of the VO2 phase transition and domain structure.

The cylindrical devices with tunable positive, infinite, and negative capacitance for dynamic random access memory

2D krypton density maps in a SPT-70 Hall effect thruster by two-photon absorption laser induced fluorescence (TALIF)

There is a growing recognition of the importance of neutral density fields to the physics, and particularly facility related effects, of Hall-effect thrusters (HETs). This work presents the first high-resolution (mm scale) spatial maps of neutral density in the near-field plume of a HET using two-photon absorption laser-induced fluorescence (TALIF). We employ a 212.6 nm TALIF excitation scheme, based on a pulsed nanosecond dye laser, to map absolute krypton neutral densities in the plume of a SPT-70 HET. Absolute densities are determined via a ratio-based approach using cold-flow measurements. The diagnostic system incorporates active wavelength stabilization via a feedback-controlled dye laser with drift correction algorithms to maintain measurement accuracy through extended mapping campaigns. Neutral density maps are acquired under cold-flow conditions and four plasma-operating states (540 and 720 W at varying background pressures), highlighting the effects of power level and background pressure on the near-field neutral particle profile. These results provide important experimental benchmarks for validating computational models and advancing physical understanding of neutral behavior and electric propulsion facility effects.

Loss of TMEM65 in mice causes mitochondrial disease mediated by mitochondrial Ca2+

Abstract Transmembrane protein 65 (TMEM65) depletion in a patient caused severe mitochondrial encephalomyopathy, highlighting its clinical importance. Recent studies show TMEM65 acts as a mitochondrial Na + /Ca 2+ exchanger in vitro. Here, we generated conditional Tmem65 knockout mice to define its role in neuromuscular tissues in vivo. Both whole-body and nervous system–specific Tmem65 knockouts exhibited severe growth retardation and seizure-associated sudden death at ~3 weeks, establishing TMEM65 as indispensable for neuronal function. Additionally, skeletal muscle–specific knockout produced adult-onset myopathy preceded by elevated mitochondrial Ca 2+ . Consistently, TMEM65 ablation caused loss of Na + -dependent mitochondrial Ca 2+ export. Notably, blocking mitochondrial Ca 2+ entry by mitochondrial calcium uniporter (MCU) knockout rescued the early lethality of whole-body Tmem65 ablation, extending lifespan from ~3 weeks to &gt;1 year. These data reveal an essential physiological role for TMEM65 and suggest that modulating mitochondrial Ca 2+ may offer therapeutic value for TMEM65 misexpression and other mitochondrial diseases associated with Ca 2+ overload.

Transverse magneto-thermoelectric properties of Fe2CoSi alloy and Fe2CoSi–Pt composite films

We report a systematic evaluation of the effects of post-deposition annealing temperature and structural ordering on the anomalous Nernst effect (ANE) in Fe2CoSi (FCS) Heusler alloy thin films. The study reveals that amorphous/disordered FCS films exhibit a larger anomalous Nernst coefficient (SANE) compared to their crystalline counterparts, in stark contrast to conventional Co-based Heusler alloys, which typically show maximum SANE in highly ordered structures. Furthermore, as a strategy for enhancing transverse thermoelectric properties, we explore the (FCS)100−xPtx composite alloy films by systematically varying the Pt concentration and optimizing the composition. This method effectively enhances the transverse thermoelectric performance of the FCS-based alloys. Our findings offer valuable insights into the design and development of next-generation high-performance ANE materials.