Science China Physics, Mechanics & Astronomy最新文献

Piezo1 ion channels transduce mechanical forces through the flattening of their intrinsically curved transmembrane dome, a process modulated by the cortical cytoskeleton. Although experiments consistently show that the cytoskeleton elevates the channel’s half-activation tension—a phenomenon known as mechanoprotection—its mechanistic basis has remained unclear. Here, we develop a continuum framework that couples the elastic Piezo1 dome, the Helfrich lipid bilayer, and a two-dimensional tilted-spring model of the cortical cytoskeleton. Our results indicate that cytoskeletal coupling pre-flattens the dome, spatially confines the membrane footprint, and reduces the projected-area reservoir available for gating. These effects raise the half-activation tension from 1.90 to 3.15 mN/m, broaden the gating curve, and convert Piezo1 from a sharp binary switch into a graded mechanical rheostat, in quantitative agreement with single-channel measurements. Parameter-matched comparison with a vertical Winkler foundation model shows that the mechanoprotective shift is dominated by vertical cytoskeletal support, while lateral tension renormalisation provides only a secondary correction. This work offers a unified, energetics-based explanation for cytoskeletal mechanoprotection, highlighting how membrane-cytoskeleton coupling reshapes the energetic landscape of Piezo1 gating and expands its physiological dynamic range.

We propose a linear model to quantify the feedthrough effect on the evolution of shock-accelerated fluid layers with arbitrary density stratification. The model is formulated explicitly in terms of the post-shock Atwood numbers of both interfaces, the dimensionless layer thickness, and the linear growth rates of a single shocked interface. Based on the concise framework, we first identify that feedthrough strength exhibits non-monotonic behavior with increasing dimensionless layer thickness within specific parameter ranges, which is contrary to widely accepted views. This non-monotonic behavior stems from competition between two physical mechanisms: the inertial response and the transport of perturbed velocity. The findings provide a theoretical foundation for optimizing the thickness and perturbation spectra of material layers in inertial confinement fusion capsule designs.

Sgr A* exhibits a persistent negative circular polarization (CP) at 230 GHz, offering a powerful probe of the magnetic field geometry in its accretion flow. Using a stationary semi-analytic radiatively inefficient accretion flow (RIAF) model in Kerr spacetime with polarized radiative transfer, we systematically analyze CP images for six poloidal magnetic field configurations across varying black hole spins, inclinations, and field polarities. We find that the CP production is dominated by Faraday conversion in radial, parabolic, quadrupole, and combined magnetic field geometries, while it is dominated by intrinsic emission in dipole and vertical magnetic field configurations. The radial and parabolic configurations produce the polarity-invariant net CP, while dipole and vertical fields yield the polarity-sensitive one. As the accretion disk is prograde with respect to the black hole spin, the CP production across all six field geometries is found to be lower in the high-spin case, while the situation is more complicated in the retrograde case. Moreover, the net CP observed from edge-on views V_net ≈ 0 except for the quadrupole geometry. Comparing with ALMA data, the reversed-field model is excluded at high inclinations, and then the magnetic field geometry of Sgr A* is constrained.

Dielectrons from heavy flavor hadron decays not only constitute a crucial background to their thermal spectrum in high-energy nuclear collisions, from which the temperature of the quark-gluon plasma (QGP) is extracted, but also provide a valuable probe of heavy quark interactions with the QGP. Using a linear Boltzmann transport (LBT) model to describe heavy quark evolution inside the QGP and a hybrid fragmentation-coalescence model for their hadronization, we find that heavy quark energy loss softens the invariant mass spectrum of their decayed dielectrons and yields a higher value of the extracted QGP temperature, while coalescence hardens the spectrum and yields a lower value. Taking into account full medium effects leads to higher values of the extracted temperature than using vacuum baselines of heavy flavor decayed dielectrons in analyzing the experimental data. In addition, we find the angular correlations between dielectron pairs are sensitive to heavy quark interactions with the QGP: the radial flow of the QGP enhances the near-side correlations, and scatterings between heavy quarks and the QGP broaden the away-side correlations, with elastic and string interactions playing a dominant role.

The development of magnetocaloric materials is fundamentally constrained by the need to simultaneously achieve a giant magnetocaloric effect (MCE) and mechanical toughness. Here, we show that this bottleneck is overcome by treating hydrogen as a microstructural tuning parameter in a Gd-based amorphous alloy (AMA). Through controlled hydrogenation, we observe small 1–2 nm GdH₂ clusters progressively evolving into a network of 2–5 nm nanocrystals. This engineered microstructure tailors the elastic modulus distribution, transforms magnetic transition behavior, and modifies the underlying critical dynamics. Notably, two distinct hydrogen concentration thresholds govern variations in mechanical and magnetocaloric performance. The brittle-to-ductile transition occurs at 0.83 wt.% hydrogen. At this point, a critical density of GdH₂ nanoclusters enables the formation of a connected shear transformation zone network and facilitates synergistic deformation between the nanoclusters and the amorphous matrix. In contrast, the giant MCE emerges only above 1.38 wt.% hydrogen, when a continuous antiferromagnetic GdH₂ skeleton forms and suppresses long-range ferromagnetic exchange. The critical window (≽ 1.38 wt.% hydrogen) thus delivers an unprecedented combination of giant MCE (≽ 16.14 J kg⁻¹ K⁻¹ at 5 T) and large plastic strain (> 40%), thereby overcoming the challenge of achieving both concurrently. Our work establishes hydrogen-mediated nanocrystal engineering as a paradigm for designing high-performance nanocomposites.

Electron correlation effects in 3d transition-metal compounds often play an important role in shaping their low-energy electronic properties. Here, using high-resolution angle-resolved photoemission spectroscopy, we investigate the electronic correlation behavior of CrSb, an altermagnetic material. Our measurements reveal the three-dimensional electronic structure of CrSb. A band splitting of about 1.1 eV is observed, consistent with previous reports. The comparison between experiment and density functional theory calculations shows renormalization factors of approximately 1.22–1.45 near the Fermi level, indicating moderate electron correlations. Notably, the renormalization is found to be momentum-dependent and band-dependent. These results provide insight into the role of electron correlations in altermagnetic CrSb and their reshaping of the low-energy electronic structure, which may be relevant for understanding its electronic properties and potential applications.

The pursuit of customizable magnetoelectric coupling in emerging altermagnets is significant for meeting diverse functional requirements in flexible, efficient, and low-power spintronic applications. However, a major challenge remains in simultaneously achieving switchable ferroelectric polarization and tunable magnetic order. Here, we propose that Janus altermagnetic bilayers offer a solution by enabling engineered control of magnetic order alongside intrinsic sliding ferroelectricity through Janus interface design. Using a Janus altermagnetic Mo₂Cl₃Br₃ bilayer as a prototype, we find that selective ClCl or BrBr interface configurations yield distinct magnetoelectric coupling phenomena. The ClCl interface bilayer exhibits interlayer antiferromagnetic coupling and sliding ferroelectricity, where ferroelectric polarization reversal switches the band spin splitting and the spin polarization of the spin currents, but leaves the magneto-optical Kerr signal unchanged. In contrast, the BrBr interface bilayer shows interlayer ferromagnetic coupling and sliding ferroelectricity, where the magneto-optical Kerr signal is reversible upon ferroelectric polarization switching, while the spin splitting remains fixed. The Janus interface design in this work establishes a universal paradigm for on-demand magnetoelectric control and provides an alternative material platform for developing advanced spintronic logic and memory devices.

The stringent requirements for ultrahigh gain, programmable beamforming, and multiband coexistence in 5G/6G extended millimeter-wave communications are fundamentally constrained by the intrinsic bandwidth-gain trade-off of conventional metasurface antennas. Here, we propose a metasurface antenna that integrates bound states in the continuum (BICs) with aperture coupling to improve field confinement, radiation control, and impedance matching. By exploiting symmetry-protected and quasi-BIC resonances with suppressed radiation leakage, the proposed architecture enables selective resonance excitation and controllable energy localization across 20–42 GHz. Through geometric optimization of quasi-BIC meta-atoms and parametric tuning of coupling apertures, the radiating metasurface achieves an ultrahigh Q-factor of 2.1×10⁶, yielding a simulated peak gain of 22.4 dBi at 25.7 GHz and a maximum measured gain of 18.1 dBi, together with significantly improved return-loss performance compared with conventional designs. The results show that the combination of symmetrical perturbation and aperture-mediated coupling provides an effective route to balancing gain, frequency selectivity, and multiband operation. This work offers a promising strategy for high-efficiency and frequency-agile antennas in future wireless communication and sensing systems.

The conventional “trial-and-error” strategy for amorphous alloy composition development is inherently inefficient and resource-intensive, particularly in the context of complex multi-component systems where comprehensive phase diagrams are often unavailable. In this work, we introduce a machine learning (ML) driven iterative framework for the accelerated design of low-liquidus-temperature Ti-based amorphous alloys in multicomponent alloy systems. By targeting low-liquidus-temperature Ti-based alloys and selecting Cu as the key alloying element, we employ regression models to predict liquidus temperatures across 60 ternary and 11 quaternary systems. Through iterative incorporation of limited experimental feedback from prior prediction rounds, the model progressively improves its predictive accuracy and facilitates efficient identification of compositional regions associated with lower melting temperature. Using this framework, the optimal amorphous composition Ti₆₀Cu₁₁Ni₁₉Zr₁₀ is identified, exhibiting a low liquidus temperature of 1121 K. This methodology not only improves the reliability of the ML predictions with limited experimental iterations, but also provides a scalable and efficient paradigm for the future development of amorphous alloys with extensive design flexibility of properties.