Browse Articles

Redox State‐Dependent Dinitrogen Binding by an Isocyanide Analogue of 15e ^– CpCr(CO) ₂

ABSTRACT The low‐valent 15e − monovalent chromium complex, Cp*Cr(CNAr Dipp2 ) 2 ( 2 ) (CNAr Dipp2 = 2,6‐(2,6‐( i Pr) 2 C 6 H 3 ) 2 C 6 H 3 ), was isolated and serves as an isolobal analogue of the unstable, monomeric CpCr(CO) 2 fragment. Complex 2 was found to have an unusual intermediate spin ground state ( S = 3/2), which enables reversible N 2 binding to afford the 17e − low‐spin ( S = 1/2) complex, Cp*Cr(N 2 )(CNAr Dipp2 ) 2 ( 2‐N 2 ), which is a rare example of an N 2 ‐induced spin state change. Complex 2 demonstrates distinct redox activity, which allowed for a stepwise investigation of its N 2 binding ability as a function of its redox state. While 1e – reduction of 2 or 2‐N 2 under an N 2 atmosphere suppresses N 2 dissociation to give a saturated dinitrogen‐bound monoanionic species, KCp*CrN 2 (CNAr Dipp2 ) 2 ( 4 ), further reduction leads to complete N 2 dissociation to afford the dianionic unsaturated metalloradical, K 2 Cp*Cr(CNAr Dipp2 ) 2 ( 5 ). This demonstrates how N 2 binding at metal centers is affected by subtle changes to electronic structure, a concept of critical importance to catalytic N 2 reduction.

Mesenchymal stem cell-extracellular vesicles deliver microRNAs that prevent nerve growth factor-induced sensory neuron sensitization

Osteoarthritis (OA) affects 600 million individuals globally, pain being a hallmark symptom. Emerging clinical evidence supports the use of mesenchymal stem cells (MSCs) and their extracellular vesicles (MSC-EVs) for pain relief in knee OA. In mice, MSC-EVs ameliorate OA-induced pain and normalize knee-innervating neuron excitability. Moreover, it has been shown that overnight incubation of sensory neurons with MSC-EVs prevents the OA-associated mediator nerve growth factor (NGF) sensitizing sensory neurons. Here, conducting experiments with male and female C57BL/6J mice, we found that protease-mediated MSC-EV ‘shaving’ inhibited MSC-EV internalization into sensory neurons and the ability of MSC-EVs to prevent NGF-induced sensitization. In addition, acute, 10-minute, exposure of sensory neurons to MSC-EVs was also insufficient to counteract NGF. We hypothesized that MSC-EVs trigger transcriptional changes and found that inhibiting transcription prevented NGF-induced sensitization. MicroRNAs (miRNAs) can be delivered to cells by MSC-EVs, and certain miRNAs regulate transcription and pain; small RNA-sequencing of our MSC-EVs identified three candidate miRNAs, miR-21-5p, miR-148a-3p and miR-451a. Using gold nanoparticle delivery, each miRNA was able to prevent NGF sensitization of sensory neurons, a combination of all three showing the most pronounced effect. These findings demonstrate that MSC-EVs prevent NGF-induced sensory neuron sensitization via cellular uptake and transcriptional regulation that is mediated by miRNAs. Significance statement Mesenchymal stem cell extracellular vesicles (MSC-EVs) contain a complex biomolecular cargo and modulate cellular activity through diverse signaling mechanisms. MSC-EVs alleviate pain in osteoarthritis (OA) through direct activity of sensory neurons whereby they prevent OA-induced hyperexcitability, as well as sensitization induced by nerve growth factor (NGF). Here, we show that MSC-EV internalization and induction of transcription is required to prevent NGF-induced sensitization. Using gold nanoparticle delivery, we further demonstrate that a cocktail of microRNAs (miRNA) enriched in MSC-EVs can recapitulate the ability of MSC-EVs to counteract NGF, miR-21-5p being most potent when administered alone.

SGLT2i attenuates biventricular remodeling and preserves connexin 43 in experimental volume-overload heart failure

Abstract Heart failure (HF) caused by chronic volume overload is associated with progressive structural, electrical, and metabolic remodeling, leading to ventricular dysfunction and increased arrhythmogenic risk. Although sodium–glucose cotransporter-2 inhibitors (SGLT2i) provide significant cardioprotection, their glucose-independent mechanisms remain incompletely understood. This study examined the effects of the SGLT2i empagliflozin on biventricular myocardial remodeling in a rat model of volume-overload HF induced by aortocaval fistula (ACF), with emphasis on extracellular matrix (ECM) remodeling and gap-junctional communication. Volume overload resulted in pronounced cardiac hypertrophy, ventricular dilation, fibrosis, oxidative stress, and cellular injury, accompanied by reduced and mislocalized connexin 43 (Cx43) and increased connexin 45 (Cx45) expression. These changes were associated with elevated pro-fibrotic and stress markers (GDF15, Galectin-3, FGF21) and altered protein kinase C (PKC) signaling. SGLT2i treatment significantly attenuated hypertrophy, reduced collagen deposition, oxidative stress, and tissue damage, and partially improved systolic function. Importantly, SGLT2i preserved Cx43 expression and Ser368 phosphorylation, prevented maladaptive Cx45 upregulation, and improved ECM remodeling. Modulation of PKCε and PKCδ suggests activation of protective intracellular pathways. In conclusion, SGLT2i exerts multifaceted cardioprotective effects in volume-overload HF independent of glycemic control, improving structural and electrical myocardial integrity and potentially reducing arrhythmogenic risk.

High-resolution chromatin mapping reveals that CTCF anchors meiotic loops to the chromosome axis

Abstract When precursor germ cells enter meiosis, chromosomes condense into an array of chromatin loops. Using Hi-C and Micro-C, we explored the trajectory of chromatin reorganization from mouse spermatogonia to spermatocytes at the highest temporal and spatial resolution to date. We show that meiotic chromatin reorganization, characterized by a shift from mitotic-to-meiotic cohesins, precedes the traditionally defined meiotic entry point (meiotic G1/S-phase). We find that large-scale A/B compartments are lost during prophase I, while local sub-compartments and interactions between regulatory elements of gene expression remain. For the first time, we detect distinct looping positions in mammalian meiosis I prophase. These loops are anchored by a subset of CTCF sites at the base of chromatin loops but formed without enriched interactions within the intervening regions, deviating from the typical pattern observed in somatic interphase cells. Our findings allow us to reconcile the current discrepancy in the length of meiotic chromatin loops and support a model where meiotic loops are formed by association of existing loops modulated by CTCF rather than by loop extrusion.

Isolable <i>C</i> ‐Phosphonio‐Boratavinyl Anion

ABSTRACT A persistent C ‐phosphonio boratavinyl anion 1 has been successfully synthesized. This boron‐containing vinyl‐lithium 1 , featuring a vinyl carbon with a negative charge (−1.59), considerably higher than that of carbon analogue 7 (−0.76), exhibits strongly nucleophilic and basic properties, as demonstrated by the results of rapid reactions with H 2 (10 bar, 15 min or 1 bar, 2 h at RT) and C 6 F 6 (1 equiv., 15 min at −80°C). The reactions of boratavinyl anion 1 with electrophiles offer a convenient route for the introduction of a borata‐alkene‐based bulky and σ,π‐double‐donating substituent, enabling to efficiently stabilize reactive intermediates such as halogenogermylenes. Furthermore, the reaction with CO 2 takes place at the borata‐alkene moiety, rather than at the P‐ylide function, resulting in the double insertion of CO 2 into the B─C bond to afford a unique cyclic P‐ylide 13 .

A comparative study of the growth, yield, and physiological responses of arbosana, arbequina, coratina, and maraqi olive cultivars

Abstract Expanding olive cultivation into newly reclaimed sandy soils faces challenges from salinity, low fertility, and limited water-holding capacity. Success depends critically on cultivar selection, yet comparative information remains limited. This study evaluated four olive cultivars (‘Arbosana’, ‘Arbequina’, ‘Coratina’, ‘Maraqi’) in Egypt’s Wadi Al-Natrun region over two seasons (2024–2025) using a randomized complete block design with four replications. Measurements included vegetative growth, physiological stress indicators (SPAD, RWC, proline), reproductive traits, yield components, fruit properties, and oil content. Significant genotypic variation ( p  &lt; 0.001) revealed three distinct performance profiles. ‘Coratina’ showed the most vigorous growth (canopy volume: 8.2–8.5 m³) and highest yield (21.2–22.5 kg tree⁻¹) and oil content (51.0–52.0%), but exhibited lowest RWC (68.8–75.4%), highest proline (12.5–14.2 µmol g⁻¹ FW), and lowest fruit set (0.9–1.2%). ‘Arbequina’ and ‘Arbosana’ showed constrained growth (3.1–3.6 m³) but maintained high RWC (78.9–87.2%), low proline (3.1–6.5 µmol g⁻¹ FW), superior fruit set (3.3–4.2%), and highest yield efficiency (3.6–3.8 kg m⁻³). ‘Maraqi’ displayed intermediate growth (5.6 m³) with highest RWC (86.2–88.5%) and lowest proline (2.8–3.0 µmol g⁻¹ FW), but yield efficiency was low (2.8 kg m⁻³) and fruit set declined 21.4% in the second season. Significant Cultivar × Year interactions indicated differential environmental sensitivity. No single cultivar is universally superior; optimal selection depends on matching performance profiles to production goals, orchard design, and resource availability.

Photo-activated digital resistive switching in a cryogenic photomemory

Abstract Resistive switching is the basis of many emerging memory technologies. However, its operation at cryogenic temperatures remains scarce, and it generally lacks compatibility with optical control and in-situ electrical programmability. Here, we report the discovery of a photo-activated digital resistive switching effect in a cryogenic photomemory based on α-In 2 Se 3 . After an optical pulse, the device can be repeatably switched from a high- to a low-resistance state digitally, which persists long after the photoactivation. The switching threshold voltage can be continuously tuned over a wide range by the reset voltage pulse, additional optical pulses, and electrostatic gating, providing multimodal control over the memory logic. The device also exhibits a markedly enhanced photoresponse and resettable persistent photoconductivity, allowing the emulation of synaptic behaviors at cryogenic temperatures. Our work reveals a defect-mediated mechanism for embedding programmable digital logic into a nonvolatile photomemory, establishing a versatile platform for adaptive optoelectronics at cryogenic temperatures.

Manganese‐Catalyzed Asymmetric Transfer Hydrogenation of Polarized Olefins via a Collaborative Hydrogen Transfer Process

ABSTRACT Asymmetric (transfer) hydrogenation of olefins is an important route to chiral molecules used in pharmaceuticals, agrochemicals, and fine chemicals. Although this transformation is well established with ruthenium‐, rhodium‐, and iridium‐based catalysts, analogous reactions catalyzed by earth‐abundant metals remain limited, particularly for acyclic olefins. Here we report a manganese catalytic system that enables highly enantioselective reduction of both cyclic and acyclic olefins, delivering diverse chiral products in up to 99% yield and &gt;99% ee . Density functional theory (DFT) studies indicate that the reaction proceeds predominantly through a concerted hydrogen‐transfer pathway involving a six‐membered transition state. These results expand the scope of manganese‐catalyzed asymmetric olefin transfer hydrogenation and provide mechanistic insight into hydrogen transfer by base‐metal catalysts.

A multi-modal agent attention model for alzheimer’s disease diagnosis with structural MRI and clinical data

Photonic scaffolds as ultrahigh-openness on-chip hollow-core waveguides for quantum photonics and optofluidics

Abstract On-chip hollow-core waveguides enable strong light-matter interaction in gases and liquids with high integration density, yet limited side access to the core restricts their use in diffusion-driven processes. We introduce a distinct class of on-chip hollow-core waveguides that confines light in a scaffold membrane geometry composed predominantly of air, reaching cladding-openness fraction up to 80% while maintaining optical losses comparable to fully enclosed waveguides. Light guidance in the photonic scaffold is enabled by the combination of anti-resonant confinement with Bloch-mode formation in a segmented structure. High-precision 3D nanoprinting, extensive optical characterization and a resonator-based theoretical model confirm the guiding principle and loss behavior. We demonstrate application relevance through enhanced molecular diffusion, highly integrated optofluidic spectroscopy, and efficient single-photon transmission enabled by the open scaffold geometry and air-dominant guidance.

Quantification of Molecule‐Defect Site Binding Force Via Single‑Molecule Adhesion

ABSTRACT The binding strength between reactant molecules and active sites fundamentally governs reaction selectivity and efficiency, as it determines adsorption energy and activation barriers at the molecular level. However, direct quantification of such molecule‐site binding forces remains challenging, since conventional spectroscopic and microscopic techniques only provide ensemble‐averaged information. Here, we leverage a single‐molecule force imaging strategy that enables quantitative mapping of local binding forces with high spatial resolution under realistic liquid conditions. By covalently tethering functional molecules such as dopamine onto an atomic force microscopy tip, we directly measure site‐specific interaction forces, revealing markedly stronger adhesion at defective sites on MoS 2 with 218 pN compared to non‐defective regions with 120 pN. Correlating these force signatures with catalytic performance allows quantitative linking of local binding strength to reactivity, yielding reactivity maps at the nanometer scale. This approach extends to other catalysts, including TiO 2 , providing a broadly applicable route to visualize structure–reactivity relationships at the single‐molecule level.

Cigarette smoke drives polystyrene nanoparticles-associated airway epithelial damage and chronic obstructive pulmonary disease-like features

Fractionated proteomics identifies a protein network mitigating resistance exercise-induced damage in human skeletal muscle

Abstract Resistance exercise (RE) improves strength and muscle mass, with multiple benefits for human health. However, intense RE also induces acute myofibrillar damage. The molecular mechanisms that preserve, mark, degrade, and restore damaged proteins to keep skeletal muscle working under RE are incompletely understood. Based on repeated sampling of human skeletal muscle, we show here that acute, repeated and interrupted RE induce dynamic changes of the protein landscape associated with the sarcomeric cytoskeleton. These changes correlate with changes in phosphorylation indicative of adaptation and deadaptation signaling footprints. Regulation mainly affects the protein network linked to the muscle maintenance protein BAG3, which includes mechanosensory proteins, small heat shock proteins, and a lipid droplet associated protein. All network components exhibit altered phosphorylation and increased cytoskeletal association after damaging RE. Moreover, network components cooperate to recognize strained skeletal muscle structures and mediate their degradation through chaperone-assisted selective autophagy (CASA). Our study thus identifies key regulators of skeletal muscle homeostasis in humans.

Periplasmic FeS Electron Conduits: Tuning Electrocoupling and Respiratory Dehalogenation in a Synthetic Consortium

ABSTRACT Electron delivery within and between bacterial cells is a central bottleneck in anaerobic biotransformation of electron acceptor‐type substrates (EATS). Using hexabromocyclododecane (HBCD) as a model organohalogen, we developed a cysteine desulfhydrase (CSD)‐associated periplasmic FeS biomineralization strategy in a defined synthetic consortium. CSD‐associated FeS formation enabled rapid installation of FeS conduits in non‐sulfate‐reducing bacteria within ∼3 h, forming predominantly periplasmic conductive interfaces that lowered interfacial charge‐transfer resistance and increased capacitive electron storage. Electrochemical analyses revealed coculture‐specific electron‐transfer behavior, increased electron‐accepting capacity, and enhanced transport activity; cocultures outperformed monocultures, consistent with strengthened interspecies electron transfer. Detection of lower‐brominated intermediates and bromide release supported dihaloelimination‐dominated debromination, with Fe‐matched cell‐free FeS accounting for only 2.8% of the live‐cell Br − signal. Inhibitor profiling further suggested that FeS alters electron‐transfer behavior from NADH/menaquinone‐linked steps toward terminal reductive processes, consistent with relief of respiratory bottlenecks. Structure prediction and docking support a working model in which a QueG‐like, cobalamin‐dependent candidate terminal reductase may participate in HBCD reduction, while FeS conduits enhance local electron delivery, charge‐transfer behavior, and whole‐cell debromination. Overall, periplasmic FeS conduits provide a CSD‐associated interfacial strategy to modulate electron flux in this defined coculture, highlighting a potentially transferable route for transforming emerging organohalogens and other EATS.

Hyperpolarized 129Xe MRI using dissolution dNP on a commercial polarizer: from solid-state optimization to in vivo lung imaging

Abstract Hyperpolarized ¹²⁹Xe gas is a powerful diagnostic tool in pulmonary MRI, uniquely enabling imaging of ventilation and gas exchange through its dissolved-phase signal. While xenon is conventionally hyperpolarized using spin-exchange optical pumping (SEOP), an alternative approach based on dynamic nuclear polarization (DNP) followed by sublimation has emerged. However, xenon DNP has so far been restricted to custom-built hardware and primarily explored for solid-state physics applications. In this work, we establish optimized conditions for solid-state polarization of xenon using a commercial DNP polarizer. The resulting robust and reproducible protocol enables in vivo imaging in porcine lungs, providing sufficient signal to extract biologically relevant information comparable to that obtained with SEOP. This work bridges a critical gap in xenon DNP, advancing it from proof-of-principle demonstrations on specialized systems to implementation on standardized instrumentation suitable for in vivo applications.

Observation of a relativistic analog of the Brewster effect in electron-photon scattering

Abstract The scattering of light by relativistic charged particles is a fundamental process in electrodynamics, underpinning phenomena ranging from cosmic ray interactions to laboratory X-ray generation. While the spectral and temporal properties of this process are well understood, the polarization-dependent response as a function of incidence angle has remained largely unexplored. Here we report the experimental observation of a relativistic analog to the Brewster effect in the interaction between a high-brightness relativistic electron beam and an optical laser pulse at shallow incidence. For incident radiation polarized in the plane of scattering, Lorentz-transformations predict a distinct interaction angle at which photon emission is suppressed in the forward direction, in close analogy with Brewster reflection at dielectric interfaces. These results connect a central concept of classical optics to the relativistic electron-photon scattering and highlight polarization as a controllable degree of freedom in light-matter interactions involving high-energy particle beams.

Molecularly imprinted electrochemical sensor based on poly(3,4-ethylenedioxythiophene)/carboxylated biochar for ceftiofur estimation in milk

Author Correction: Bacterial detoxification of plant defence secondary metabolites mediates the interaction between a shrub and frugivorous birds

Comparison of volar plating and headless compression screw for fixation of scaphoid nonunion: a meta-analysis of comparative studies

Abstract This study compared the clinical and radiological outcomes of volar plating versus headless compression screw fixation for scaphoid nonunion using a meta-analysis. A comprehensive search of PubMed, Cochrane Library, and EMBASE databases was conducted to identify comparative studies evaluating volar plating versus headless compression screw fixation for scaphoid nonunion. Pooled analyses assessed union rate, time to union, range of motion, grip strength, Disabilities of the Arm, Shoulder, and Hand (DASH) score, and hardware-related complications. Seven studies (two prospective and five retrospective studies) involving 226 participants were analyzed. Pooled analysis showed comparable high union rates between volar plating and headless compression screws. Plate fixation was associated with a significantly shorter time to union. The rate of implant removal owing to symptoms or implant-related complications was higher in the plate fixation group. Extension range of motion was decreased in patients treated with plate fixation, whereas grip strength and DASH scores were similar between the groups. Overall, both fixation methods showed comparable union rates and functional outcomes, while volar plating was associated with a shorter time to union but higher implant removal rates.

Control of associative learning by the mediodorsal thalamus-orbitofrontal cortex circuit