Physics

A newly designed, highly volatile liquid molybdenum precursor, Mo(CO)5P[OCH(CH3)2]3, was synthesized and implemented for the first time in thermal atomic layer deposition (ALD). This precursor is engineered in the liquid phase to simultaneously achieve high volatility and stable vapor delivery, and there have been no prior reports on the ALD growth mechanism or device-level applicability enabled by this chemistry. Using this precursor, we systematically elucidate oxidant-dependent growth behavior, ligand decomposition pathway, and crystallization characteristics of thermal ALD molybdenum oxide (MoOx, 2 < x < 3) thin films. MoOx was deposited at 280 °C and 1 Torr for 200 cycles under O2 and H2O-based oxidizing environments, and the growth per cycle, structure evolution (XRD, Raman), and chemical states (hard x-ray photoelectron spectroscopy) were systematically quantified. Although both oxidants yielded amorphous MoOx in the as-deposited state, postannealing at 550 °C induced preferentially oriented α-MoO3 crystallization only in the H2O-processed films. Structural and chemical analyses indicate that H2O promotes ligand hydrolysis and surface –OH-mediated Mo–O–Mo condensation, increasing the Mo6+ fraction and enabling the formation of near-stoichiometric α-MoO3, whereas O2 fails to induce equivalent structural reordering pathway. To validate device-level implications, the H2O-derived α-MoO3 was incorporated as a hole-selective contact in PM6:L8-BO near-infrared organic photodetectors, achieving a responsivity of 0.7722 A W−1, detectivity of 4.38 × 1013 Jones, and microsecond-scale temporal response. These results establish a custom-synthesized liquid precursor as a viable platform for H2-free ALD and identify oxidant selection as a primary process knob governing structure ordering and optoelectronic functionality in ALD-grown transition-metal oxides.

Vapor-pressure mismatched materials (materials whose constituent elements have significantly different vapor pressures) such as transition metal chalcogenides have emerged as electronic, photonic, and quantum materials with scientific and technological importance. While hybrid pulsed laser deposition (hPLD) has emerged as a method for epitaxial or textured growth of vapor-pressure mismatched materials, carbon (C) incorporation has been a persistent concern—especially in instances where organic chalcogen precursors are desired as a less hazardous alternative to more toxic chalcogen hydrides. However, the underlying mechanisms of such unintentional C incorporation and the effects on film growth and properties in hPLD are still elusive. Here, we report on the influence of C-containing side-products of organosulfur precursor pyrolysis in ZnS, BaTiS3, and TiS2 thin films grown by hPLD using a tert-butyl disulfide (TBDS) precursor. By combining the structural characterization of x-ray diffraction (XRD) and atomic force microscopy with secondary ion mass spectrometry, we systematically investigate the role of temperature and TBDS partial pressures on film morphology and crystallinity. ZnS, TiS2, and BaTiS3 have optimal growth temperatures of 400 °C, 500 °C, and 700 °C, respectively, and we observe that samples grown at temperatures above or below have increased C incorporation in the bulk and interface of the film, which correlates with poorer texture of the films as determined by XRD. On the other hand, highly textured films have minimal C at the film-substrate interface and within the film, which are comparable to films grown without TBDS in nominal vacuum conditions. We report TiS2 growths with C incorporation dependent on TBDS growth pressure and determine that 10−1 Pa TBDS is the optimal growth pressure for minimal C contamination. At partial pressures greater than 10−1 Pa, there is no preferential texture of the film, which is possibly caused by the graphitization of C, poisoning the interface and bulk of the film. This work opens opportunities for further understanding process-induced C impurity presence in the hPLD grown thin film transition metal chalcogenides and chalcogenide perovskites and might have important implications for sulfide-based thin film technological applications.

In this study, InAs/GaSb type-II superlattice (T2SL) structures were grown on GaSb substrates by molecular beam epitaxy to investigate the impact of arsenic species (As2 dimers vs As4 tetramers) and growth temperatures (385–425 °C) on the interface quality and device performance. Structural characterization revealed that InAs layers grown with As4 at 385 °C exhibit superior crystallinity, evidenced by sharper higher-order satellite peaks and minimal lattice strain in high-resolution x-ray diffraction patterns. High-resolution transmission electron microscopy further confirms the abruptness of the interface with suppressed intermixing. Photoluminescence measurements demonstrate enhanced emission intensity and narrower linewidths for samples grown with As4 at 385 °C compared to those grown with As2. The reduced reactivity and sticking coefficient of As4, relative to As2, likely suppress uncontrolled anion exchange, particularly at lower growth temperatures. In contrast, As2 facilitates direct substitutional incorporation, driven by lower activation energy barriers, which promotes aggressive As-Sb exchange at heterointerfaces. This leads to compromised crystal integrity through the formation of parasitic ternary/quaternary phases and an increase in nonradiative defect centers, which adversely affect optical performance. Fabricated p-i-n diodes utilizing the optimized As4-grown T2SL exhibit a low room-temperature dark current density of 2.2 × 10−5 A/cm2, attributed to the suppression of generation-recombination and tunneling currents via enhanced interface quality. These results demonstrate that As4-mediated growth effectively mitigates anion exchange, paving the way for high-operating-temperature T2SL devices in midwave infrared optoelectronics.

Auroral kilometric radiation (AKR), Earth’s strongest radio emission, has long been associated with discrete auroras and electrons near a few kilo–electron volt (keV) range. However, auroras also occur in diffuse forms with broader electron energies, raising the question of why AKR has not been observed above diffuse auroras or linked to electrons outside the kilo–electron volt population. Comprehensive AKR source distributions have remained elusive because of observational limitations, and their local-time coverage remains largely unknown. Using spacecraft measurements, we identify a “radio oval” above the optical auroral oval, spanning the full local-time range, where AKR is emitted over both discrete and diffuse auroras. The AKR source electrons display diverse precipitation features, including monoenergetic (peak flux at 3.82 kilo–electron volts), broadband (1.34 kilo–electron volts), low-energy (0.47 kilo–electron volts), and diffuse types (>1 kilo–electron volt). These results reveal that the cyclotron maser instability—the mechanism driving AKR—can arise in diverse plasma environments, broadening our understanding of both AKR generation and auroral complexity.

Efficient oral delivery of RNA to the target site is a long-standing issue for nucleic acid–based therapy. Herein, we adopted a vesicle-to-vesicle transfer strategy and established an efficient approach to encapsulate and stabilize RNA for targeted oral delivery. The amphiphilic specifically acylated epigallocatechin directly performed encapsulation of RNA and generated nanovesicles in high efficiency without assistance of additional materials. The RNA encapsulated in the nanovesicles was efficiently transferred to outer membrane vesicles (OMVs) derived from Escherichia coli Nissle 1917 probiotic through membrane fusion with simple operation. The derived hybrid vesicles (HVs) were further anchored with bilirubin and Lys-Asp-Glu-Leu grafted hyaluronic acid (HA-BR-KDEL) ligand for sequential cellular and intracellular targeting to the endoplasmic reticulum of inflammatory cells in inflamed intestinal tract. Oral delivery of HVs@HA-BR-KDEL notably alleviated colitis symptoms in mice and contributed to the restoration of intestinal homeostasis. The tea polyphenol hybrid OMV strategy holds great promise for oral gene-mediated treatment.

Chiral optical cavities are crucial for the development of nonequilibrium quantum materials by discriminating and selectively coupling to light of a specific circular polarization, but fundamentally cannot be realized with conventional mirror cavities. Here, we demonstrate this unique functionality by developing a monolithic transition metal dichalcogenide (TMDC) metasurface with broken out-of-plane symmetry, allowing for the selective formation of self-hybridized chiral exciton-polaritons. Our metasurface maintains maximal chirality for oblique incidence up to 20°, thereby outperforming all previously known designs. Moreover, we study the chiral strong-coupling regime in nonlinear experiments and reveal polaritonic signatures in chiral third-harmonic generation. Our results position maximally chiral van der Waals (vdW) metasurfaces as a versatile platform for tunable chiral polaritonics with applications in nonreciprocal photonic devices and valleytronics.

Acute myeloid leukemia (AML) is a hematopoietic malignancy caused by abnormal proliferation and differentiation of blasts. PRMT5, a methyltransferase that catalyzes symmetric dimethylation of arginine (SDMA) residues, has been implicated in cancer stem cell homeostasis and shown to be a potential therapeutic target in AML. However, given the toxicity of complete PRMT5 inhibition, there is a need to identify effective synergistic therapies. Through a targeted screen of compounds that inhibit key nodes of PRMT5-regulated pathways, we identified a synthetic lethality between inhibition of PRMT5 and LSD1, a lysine demethylase known to affect AML blast differentiation. The two inhibitors broadly reshape the transcriptome of targeted cells and synergize to promote AML differentiation and eventually growth inhibition and apoptosis, in a p53-dependent manner. To leverage this synthetic lethal interaction, we generated new dual compounds to inhibit both enzymes and recapitulated the effects of the drug combination. Our results uncover an unexpected convergence of PRMT5- and LSD1-regulated targets, paving the way for new therapeutic opportunities.

Resolution in NMR is defined as the ability to distinguish and accurately determine signal positions while mitigating overlap. In the pursuit of ultimate resolution, we introduce peak probability presentations ( P 3 ), a statistical spectral representation that assigns a probability to each spectral point, indicating the likelihood that a peak maximum occurs at that location. The mapping between the traditional spectrum and P 3 is achieved using MR-Ai, a physics-inspired and computationally efficient deep-learning neural network. P 3 is validated on 60 database proteins and showcased on the challenging Tau and MATL1 proteins. Using synthetic spectra, we show that the achieved peak-localization precision closely approaches the theoretical limits set by the Cramér-Rao lower bound and Bayesian Monte Carlo estimates. Furthermore, MR-Ai enables the coprocessing of multiple spectra, facilitating direct information exchange between datasets to enhance spectral quality, particularly in cases of highly sparse sampling.

Benzonitrile is vital for the production of rubbers, pharmaceuticals, and dyes. Traditional benzonitrile synthesis via toluene ammoxidation requires high temperatures (≥350°C), leading to high energy consumption. Here, we demonstrate a photocatalytic route for benzonitrile synthesis under milder conditions (100° to 120°C, 1 to 4 bar, blue light irradiation). Using ammonia, dioxygen, and toluene as precursors, gram-scale benzonitrile (1.751 grams) was produced over a mixture photocatalyst [lead-free halide perovskite cesium bismuth bromide (Cs 3 Bi 2 Br 9 ) + titanium dioxide], demonstrating satisfactory selectivity (85 to 90%) and a linear yield rate of 600 μmol hour −1 . The photocatalyst exhibited excellent quantum efficiencies (up to 40%) and maintained stability over a 30-hour test period. Mechanism studies revealed that, in the presence of an interfacial effect, the perovskite phase primarily activated benzyl carbon (sp 3 )–hydrogen bonds, while titanium dioxide facilitated the oxidation of alcohol intermediate to aldehydes. These benzaldehydes were subsequently converted to benzonitriles via ammoxidation, predominantly catalyzed by Cs 3 Bi 2 Br 9 through aldimines (RCH═NH).

For oxide-supported metal catalysts, metal-support interaction (MSI) facilitates metal dispersion at the expense of the metallic character, resulting in a trade-off between active site utilization and intrinsic activity. Here, we used a thermal aging strategy to modulate the MSI in Cu/CeO 2 catalysts, facilitating the formation of metallic Cu sites upon H 2 reduction while maintaining metal dispersion. Systematic experiments confirmed that thermal aging at 800°C lowered the reduction temperature and increased the reduction degree of Cu sites. Microscopy evidenced few-atom-layered Cu nanoclusters before and after H 2 reduction, whereas in situ spectroscopy revealed metallic Cu nanoparticles under H 2 atmosphere. This discrepancy indicated a reversible structural evolution from aggregation to redispersion in thermally aged Cu/CeO 2 . The catalytic activity for acetylene semihydrogenation was unlocked on metallic Cu sites, compared to nearly inactive Cu sites in conventional Cu/CeO 2 counterparts. Our work developed an effective strategy for rational modulation of MSI, offering the feasibility to tailor-make active sites for specific reactions.

Mammalian odorant receptors (ORs) sense diverse environmental chemicals, yet structural insights into odorant recognition by mammalian class II ORs remain limited. Here, we present the cryo-EM structure of a native mammalian class II OR, mouse Olfr412, a human OR1D2 ortholog, bound to the odorant methyl- trans -cinnamate and the G s protein. The odorant-binding pocket of Olfr412 is located deeper within the transmembrane domain than that of the class I OR OR51E2 and is largely composed of poorly conserved hydrophobic residues, providing a structural basis for broad odorant recognition in class II ORs. Structural and molecular dynamics analyses suggest that the conserved Y 6x55 plays a key role in odorant recognition and activation, functionally paralleling R 6x59 in class I ORs and is further stabilized by intramolecular interaction with the conserved ECL2 residue E 45x51 . Together, our findings uncover structural mechanisms underlying odorant recognition and activation in class II ORs.

Heat stress impairs plant development by disrupting essential molecular processes. Alternative splicing (AS) is emerging as a key regulatory mechanism in heat responses, yet how stress-responsive AS is fine-tuned within core splicing regulators remains underexplored. Here, we uncover a heat-activated, autoregulatory splicing switch in the serine/arginine-rich factor SR45a, critically dependent on intron 4. Using an intron 4–based luciferase reporter, we show that heat enhances intron removal, promoting the full-length isoform over truncated variants. This switch relies on branch point (BP) recognition, with SR45a and cap-binding protein 20 (CBP20) coordinating BP-dependent splicing under stress. Overexpression of either protein enhances thermotolerance by stabilizing AS dynamics. HSFA2 directly activates SR45a transcription, linking transcriptional and splicing control. Notably, intron 4–mediated splicing is conserved in both maize and wheat, suggesting its potential as a portable regulatory module in crops. Our study establishes a stress-inducible SR45a-CBP20-BP axis and introduces an intron-based strategy for engineering thermotolerance via precision splicing control.

Mitochondrial dysfunction and dysregulated proteolysis drive Huntington’s disease (HD), tauopathy, and related neurodegenerative disorders. Calpain-2, a Ca 2+ -activated protease restrained by calpastatin (CAST), is pathologically overactivated, yet no therapies directly target this axis. We identify A36, a brain-penetrant small molecule derived from CHIR99021 that selectively stabilizes the CAST–calpain-2 complex without inhibiting GSK3. A36 acts as a protein-protein interaction stabilizer, enhancing CAST–calpain-2 binding, preventing CAST degradation, and thereby limiting calpain-2 activation and mitochondrial damage. In patients with HD induced pluripotent stem cell–derived neurons and mutant mouse striatal neurons, A36 normalized mitochondrial morphology and membrane potential, reduced oxidative stress, and improved survival. In vivo, A36 displayed favorable pharmacokinetics and central nervous system exposure; treatment reduced striatal neurodegeneration, mutant huntingtin aggregation, and motor deficits in HD R6/2 mice, and lowered phosphorylated tau, neuroinflammation, and cognitive decline in tauopathy PS19 mice. These findings establish pharmacological stabilization of CAST–calpain-2 as a therapeutic strategy and position A36 as a mechanism-selective modulator with broad neurodegenerative disease potential.

The NLRP3 inflammasome is a multiprotein molecular machine that drives inflammatory responses in innate immunity. Although its dysregulation is implicated in numerous human diseases, its structural organization in cells remains poorly understood. Here, we used precise fluorescence-guided cryo–focused ion beam (cryo-FIB) milling and cryo–electron tomography (cryo-ET) to visualize NLRP3 inflammasomes in situ within human macrophages at various stages of activation. After priming and activation, we observed expansion and dispersion of Golgi cisternae, along with the emergence of 50-nanometer NLRP3-associated vesicles, which likely transport NLRP3 to the MTOC. Dense NLRP3-containing condensates then formed in and around the MTOC. In later stages, the condensates solidified, coincident with widespread mitochondrial damage, autophagy, and pyroptotic cell death.

Frustrated Lewis pairs (FLPs) have emerged as a transformative strategy in small-molecule activation, leveraging steric inhibition to sustain highly reactive Lewis acid–base pairs capable of heterolyzing nonpolar molecules such as H 2 and CO 2 through electric field (EF)–induced polarization. Despite their promise, FLPs exhibit inherent limitations in activating highly stable, kinetically inert substrates, owing to insufficient field strength and limited polarization efficacy. The systems with intensified charge separation, termed frustrated ion pairs (FIPs), can transcend these constraints by combining extreme ionic reactivity with persistent frustration. Here, we propose a geometrically controlled FIPs system that systematically modulates interionic distance and interaction via cation size engineering, ensuring sustained frustration and remarkable catalytic enhancement. The relationship between the interaction strength of anions and cations in the FIPs and their performance in CO 2 cycloaddition exhibits a volcanic curve trend. FIPs catalysts with optimal distance (4.11 Å) and interaction strength (−78 kJ·mol −1 ·Å −1 ) between its cation and anion exhibit optimal catalytic performance ( TOF = 184 hour −1 ). The frustrated configuration liberates Br − from electrostatic confinement, achieving unprecedented nucleophilic activity by reducing the ring-opening energy barrier by 48.7 kJ·mol −1 compared to conventional ionic pairs. Optimal ion-pair distance in FIPs generates an intense asymmetric electric field that strongly polarizes CO 2 , yielding an induced dipole moment of ∆μ = 0.132 D. Moreover, the FIPs structure is extended to heterogeneous systems and exhibits a similar trend with homogeneous ones, showing its application potential.