Small Science最新文献

Characterizing the 3D complex energy materials interface is critical to understand the correlative relationship between performance, degradation, and structures. Unfortunately, the resolution of microscopy and image acquisition speed are limited by the nature of the hardware, causing high-throughput characterization of energy materials to be prohibitive. Herein, REMind, a generative diffusion artificial intelligence model for fast and accurate reconstruction of electrode microstructures via focused ion beam-scanning electron microscopy, is presented. REMind can generate high-resolution internal microstructures between two low-resolution surfaces after training on sufficient high-resolution microstructures, enabling larger milling thickness between slices while keeping high-fidelity imaging. REMind is first demonstrated for reconstructing solid oxide fuel cell (SOFC) anode microstructures. REMind resolves relevant multi-scale structures with low pixel-wise reconstruction error (<10%) and quantifies the generated uncertainty by calculating the generated entropy. Additionally, a multi-scale multi-physics SOFC model is employed to further quantify the reconstructed error regarding the electrochemical performance, i.e., operating current density versus overpotential. REMind shows good transferability, as proven by its ability to reconstruct other energy materials, including catalyst layers of proton exchange membrane fuel cells and solid-state battery composite electrodes, demonstrating the potential for REMind to be used as a general-purpose platform for broad development of energy technology.

Recent advances in liquid-phase transmission electron microscopy (TEM) have enabled the direct visualization of reaction pathways of nanomaterials, providing critical insights into diverse nanoscale processes such as crystallization, phase transition, shape transformation, etching, and nanoparticle motions. Among various liquid cells, graphene liquid cells (GLCs) are particularly advantageous due to the intrinsic properties of graphene-high electrical and thermal conductivity, exceptional mechanical flexibility, and radical scavenging effects-which allow atomic-scale spatial resolution and enhanced imaging stability. This review article highlights the recent progress in GLC-based liquid-phase TEM, focusing on the evolution of structural designs, including veil-type, well-type, liquid-flowing-type, and mixing-type GLCs. Each configuration offers unique advantages tailored to observing distinct types of nanoscale dynamic processes. These studies have elucidated both classical reaction pathways and complex, nonclassical mechanisms involving transient intermediates. Overall, this review highlights how developments in GLC designs have significantly advanced the capabilities of in situ liquid-phase TEM, providing unprecedented opportunities to study nanoscale processes at atomic resolution.

Sustained mechanical stimulation represents a powerful strategy for directing stem cell fate, yet its application within microscale injectable carriers remains limited. This study presents a dynamic microgel platform enabling osteogenic differentiation of single mesenchymal stem cells (MSCs) solely through hydrostatic pressure, without biochemical induction. Individual MSCs are encapsulated in ionically crosslinked, cell-adhesive alginate microgels and stabilized using an alginate-poly-l-lysine-alginate and calcium coating. Application of cyclic hydrostatic pressure at 200 kPa and 0.5 Hz frequency for 30 min per day leads to upregulation of early osteogenic markers RUNX2 and alkaline phosphatase, enhanced collagen I synthesis, and mineralization over 21 days. Results demonstrate that mechanical cues alone are sufficient to orchestrate osteogenic commitment in soft, confined microenvironments, offering a scalable approach to stem cell programming. This work establishes a versatile, high-resolution platform for engineering lineage specification at the single-cell level and highlights the potential of force-driven strategies for scalable production of therapeutic stem cells.

Carbon nanotube (CNT)-based hydrogels have the potential to serve as 3D platforms for nerve regeneration. However, the interplay between different cues governing the formation of a complex tissue-like cellular structure is still ambiguous. Herein, two approaches are adopted to develop PVA/CNT hydrogels using phase inversion method and low kinetic gelation, enabling unprecedented CNT loading capacity (75% w/w) without compromising their elasticity. By controlling key factors affecting cell coverage and maturation, including Young's modulus (YM), CNT concentration, and pore size, distinct thresholds are identified where these factors dominate cell coverage. Results demonstrated that when CNT exceeds 60% w/w or a coating is applied to enhance CNT-cell interaction, CNT effect dominates, increasing cell coverage with increasing CNT concentration. However, below a specific YM threshold, YM dominates cell growth, covering up to 50% of the scaffold surface regardless of CNT concentration or exposure. Lastly, controlling the pore size to 100-250 μm further increased cell coverage to >70%, breaking through previous plateau and upregulating TUBB3 maturity marker. Additionally, certain key factors are seen to synergistically codominate in determining cell growth.

Charge transfer (CT) interactions have rarely been used to organize supramolecules and cross-linked objects. However, the ever-increasing understanding of CT interactions opens up new avenues for the design of innovative materials with tailored electronic properties. Herein, several molar ratios of highly crystalline π-conjugated n%TCNQ@Sq-1,6Py oligomers (n equal molar ratio of tetracyanoquinodimethane (TCNQ) to 1,6-diaminopyrene (1,6Py) moiety) with simultaneously stable intra- and intermolecular CT mechanisms are prepared. As a result, the π-conjugated 200%TCNQ@Sq-1,6Py CT complex indicates stable intra- and intermolecular CT interactions resulting in extremely high electrical conductivity of 8.7 × 10^-2 S cm^-1 at room temperature, a charge-distance capacitance of 70.62 F g^-1 at the current density of 0.625 A g^-1 which significantly increases to 968.7 F g^-1 by doping of polyaniline (PANI) at a current density of 0.312 A g^-1. Finally, it exhibits a capacitance retention of 70% of the initial specific capacitance after 1000 cycles at room temperature. This type of π-conjugated oligomer CT complex can be used to improve existing CT-based energy storage devices, such as capacitors.

2D Ti₃C₂T_x MXene offers high electrical conductivity and a large surface area, making it attractive for electrocatalysis. However, its intrinsic hydrogen evolution reaction (HER) activity remains poor due to the lack of active catalytic sites. To activate the otherwise inert surface, platinum monosulfide (PtS) nanoparticles are synthesized directly on Ti₃C₂T_x nanosheets via thermal decomposition of a single-source precursor, Pt(dmampS)₂, in a solution-based process. This direct growth strategy enables uniform dispersion of PtS nanoparticles and intimate interfacial contact with the MXene surface, without the need for binders or surfactants. The resulting PtS/Ti₃C₂T_x heterostructure exhibits significantly enhanced HER performance, achieving a low overpotential of -104 mV at a current density of -10 mA cm^-2 and a Tafel slope of 48.3 mV dec^-1.

Accumulation of huntingtin exon-1 protein (htt^ex1) fibrils within neurons occurs when the polyglutamine region exceeds ≈35 residues and is responsible for Huntington disease, a fatal neurodegenerative condition. Recent work has shown that selenium nanoparticles (SeNP) are protective against neurodegeneration. Herein, the mechanistic basis for SeNP modulation of htt^ex1 aggregation is explored. Fibril formation of htt^ex1 entails two distinct processes on timescales differing by many orders of magnitude: prenucleation oligomerization on the microsecond timescale to generate a low population of transient tetramers that undergo slow (hours timescale) unimolecular conversion into elongation-competent nuclei, followed by elongation and secondary nucleation. Using NMR spectroscopy, fluorescence immunostaining, and transmission electron microscopy, the interaction of SeNPs with two htt^ex1 protein constructs, htt^ex1Q₇ and htt^ex1Q₃₅ containing 7 and 35 glutamine repeats, respectively, is studied. htt^ex1Q₇ undergoes transient prenucleation tetramerization but remains largely monomeric over a period of weeks, while htt^ex1Q₃₅ forms fibrils within a period of hours. It is shown that SeNPs reduce the rate of fibril formation substoichiometrically with respect to monomer by selectively targeting and binding with nanomolar affinity to the extendable ends of elongation-competent species of htt^ex1Q₃₅, thereby reducing the pool of free extendable ends.

Self-powered sensing networks are essential for smart city infrastructure, with triboelectric nanogenerators (TENGs) emerging as a promising technology for distributed sensing and energy harvesting. However, widespread TENG implementation is hindered by moisture-induced charge dissipation in urban environments. While superhydrophobic surfaces can mitigate this issue, existing coatings lack sufficient triboelectric properties for effective charge generation, while suffering from mechanical fragility that limits practical deployment. Herein, a triboelectric-responsive superhydrophobic coating (TRSC) is reported that achieves thorough drying within 90 s at room temperature with remarkable cost-effectiveness (-2). The coating exhibits consistent superhydrophobicity (contact angle 157°) and stable electrical output after 500 cycles of mechanical abrasion, tape-peeling, and compression tests. When deployed as smart city sensors, TRSC enables solid-solid contact sensing for traffic monitoring, solid-liquid interfacial energy harvesting from raindrops, and noncontact sensing for human activity detection. The coating maintains performance under 99% relative humidity and shows excellent adhesion on various substrates regardless of surface roughness, microstructure, and geometric complexity. Compatible with automatic spraying systems and conventional equipment, this coating strategy enables large-scale manufacturing to transform existing urban infrastructure into smart sensing networks, marking a significant step toward practical smart city implementation.

Precise control of metal nanodot arrays is crucial for optimizing their plasmonic, catalytic, and photonic properties. Fabrication methods for homogeneous nanodots generally rely on complex processes, such as lithography or layer-by-layer assembly. Recently, nanodot array fabrication via metal deposition, e.g., sputtering and thermal evaporation, has received attention due to its simplicity and scalability. However, structures produced by deposition are often inhomogeneous and suffer from size limitations, because metals generally possess high surface energy in air. In this study, we propose a strategy for fabricating uniform metal nanodot arrays through thin oil layer-assisted solid-state dewetting. Metals are deposited by sputtering onto a glass substrate coated with a thin oil layer, followed by thermal annealing that induces dewetting and the formation of nanodot. Surfactants incorporated in the oil reduce the surface energy of metals, thereby suppressing undesired coalescence. Additionally, the size and shape uniformity of the resulting nanodots are improved and can be controlled by adjusting deposition thickness and/or oil layer thickness. This simple strategy, based on surface stabilization using oil/surfactant, effectively overcomes the limitations of deposition methods. Furthermore, nanodot arrays composed of various metals, or two or more metals, can be fabricated, providing a versatile and customizable platform for nanostructure engineering.

Craniomaxillofacial reconstruction is challenging due to the requirement for diverse manual surgical interventions, which significantly increase as the defect volume enlarges. To address these concerns, we utilized intraoperative bioprinting (IOB) to reconstruct cranial bone defects in surgical settings. We formulated an innovative collagen-based bioink supplemented with human adipose-derived stem cells (hADSCs) or bone morphogenetic protein-2 (BMP-2). The concentration and dispersion state of collagen along with hADSCs were precisely adjusted to enhance cytocompatibility, bioprintability, and osteogenic activities. IOB was first performed via a 3-axis bioprinter on a rat model having a critical-sized calvarial defect (39.3 mm³), which was infilled within ≈30 s and resulted in ≈90% bone coverage area in 8 weeks. Secondly, IOB was conducted on sheep calvarial defects (1,209 mm³, ≈31-fold larger compared to the rat defects) using a 6-axis robotic arm, where IOB took ≈5 min per defect. On Week 12, sheep defects treated with IOB revealed accelerated bone repair (≈80% bone coverage area) and mechanical enhancement with 240%, 235%, and 358% increments in Young's modulus, peak force, and energy compared to the non-treated group. The successful execution of IOB in small and large animal models validates the translation potential of IOB for automated surgical interventions.