Browse Articles

Three-dimensional maneuverable microrobots with single-beam actuation

Light-driven microrobots offer great opportunities for non-contact manipulation at the nanoscale but are typically restricted to planar motion and require complex optical setups. Here, we report a microrobot capable of full five-degree-of-freedom (5-DoF) motion control using a single unfocused illumination with switchable wavelength and polarization. The design integrates a hybrid plasmonic nanomotor system leveraging wavelength and polarization multiplexing for independent actuation. Specifically, a central triangular antenna dimer operating at 650 nm provides directional scattering for in-plane translation, while asymmetrically slotted nanodisks positioned at the corners and driven at 1250 nm generate differential torques for out-of-plane pitch and roll. This dual-wavelength, single-beam strategy decouples translation and reorientation control, enabling precise, addressable manipulation without optical crosstalk. The presented framework establishes a compact and versatile platform for light-driven microrobots, advancing applications in targeted drug delivery and in situ biochemical sensing.

Intelligent Parkinson’s disease identification via Residual-Shuffle Network optimized by Improved Dandelion Optimizer

Study on the pollution law of complex working conditions in sand-filled fracture well washing operation

Aiming at the problem of wellbore leakage in the process of sand washing in horizontal wells, this study systematically analyzed the influence of temperature and pressure on the plugging behavior of flushing fluid through the combination of numerical simulation and experimental experiment, and carried out field application. Based on CT technology, the fracture pore structure was reconstructed, and the particle gradation of the well flushing fluid was optimized by combining the Vickers criterion. The particle-fluid interaction model was established by CFD-DEM coupling method. The experimental and simulation results show that the increase of pressure will enhance the sand carrying capacity of fluid, which will lead to the increase of particle invasion depth and aggravate the risk of deep pollution. When the temperature increases, the shallow retention capacity of the particles is enhanced by promoting the thermal expansion of the particles and reducing the viscosity of the well flushing fluid, and the invasion depth is significantly reduced, forming an efficient shallow plugging. The research reveals the law of pressure and temperature on pollution behavior, and provides a theoretical basis for particle system optimization and process parameter design of well washing operation under complex working conditions. The field test shows that the well washing fluid suitable for the formation temperature is optimized, and the construction displacement is reasonably controlled, which can effectively reduce the leakage in the sand washing process and shorten the production recovery period

Quantifying space-charge storage in spatially confined selenides: Operando magnetometry insights for fast-charging and wide-temperature Li/Na-ion batteries

While conversion-type metal selenides are highly promising for fast-charging batteries, the microscopic origin of their ultrafast interfacial kinetics has remained largely unclear. Here, we developed a spatially confined CoSe@N-C architecture as a well-defined model platform. Using advanced operando magnetometry, we achieved quantitative decoupling of the space-charge storage contribution from conventional diffusion-controlled processes, providing direct insight into the interfacial charge storage mechanism of conversion-type metal selenides. The rigid porous carbon framework not only mitigates volume expansion but, more importantly, enforces intimate, atomic-scale contact between the in situ generated electronic (Co) and ionic (Li2Se/Na2Se) phases, maximizing the density of space-charge interfaces. Driven by this enhanced spin-electronic and ionic coupling, the spatially confined CoSe@N-C anodes deliver exceptional fast-charging capabilities and stable wide-temperature stability (from −20 to 50 °C) in both Li- and Na-ion batteries. In addition to demonstrating a high-performance electrode, this work offers quantitative insights into the space-charge mechanism, establishing a crucial physical perspective for designing next-generation ultrafast energy storage materials.

Electron repulsion integral evaluation over f-type functions on GPUs via OpenMP offloading

Evaluation of electron repulsion integrals over f-type basis functions on graphics processing units (GPUs) in the LibERI library is presented. The GPU architecture is targeted via the OpenMP programming model, re-utilizing pre-existing central processing unit-oriented code as the backbone for automatic GPU kernel generation. The electron repulsion integral calculator and Rys quadrature methods are utilized to accommodate different degrees of contraction and angular momenta. Upon comparison against GPU-native compute unified device architecture programs, the implementation presented here is observed to be competitive with state-of-the-art software for small to medium-sized systems. Multi-GPU performance is also presented. Parallel efficiencies higher than 80% are observed for large systems on 4 GPUs (i.e., a full node), and the multi-node performance of LibERI is demonstrated for up to 128 GPUs (32 nodes). The limitations of the implementation presented here are also reported.

Tensor structure and transport of centrifugal distortion constants: A representation-independent framework connecting spectroscopy and quantum chemistry beyond the linear regime

Centrifugal distortion constants provide a key link between high-resolution rotational spectroscopy and quantum-chemical rovibrational calculations. Within Watson’s Hamiltonian, the underlying structure is described in terms of tensorial objects, whereas fitted spectroscopic parameters become representation-dependent upon projection, complicating direct comparison between experiment and theory. Building on the tensorial formulation of centrifugal distortion, we show that standard quartic and sextic constants can be consistently described within a representation-independent linear tensor sector generated by first derivatives of the inverse inertia tensor so that different Watson parameterizations correspond to alternative projections of the same underlying tensorial object. An explicit inverse formulation based on a Moore–Penrose pseudoinverse enables reconstruction of tensor representatives from fitted spectroscopic parameters, leading to a lift–transport–reprojection framework for representation-independent comparison. The sextic transport problem is formulated on a canonical seven-dimensional Watson space, while the first intrinsic breakdown of the linear tensor structure is identified through the H22 contribution, marking the onset of nonlinear tensorial effects. Within this framework, we derive transformation schemes for quartic and sextic constants, introduce diagnostic indicators for nonlinearity, and show that three-index cubic force-field contributions are generally non-negligible. Applications to molecular systems of increasing size and complexity demonstrate that the tensor framework rationalizes representation dependence and provides a practical basis for multilevel and semi-experimental approaches.

Fluctuation–dissipation framework for size-dependent surface tension

The size-dependent liquid–vapor surface tension controls phase change, wetting, and transport at nanoscales, yet its first curvature correction, the Tolman length, remains difficult to determine. We develop a thermodynamic and statistical-mechanical framework that relates this correction to bulk response properties of a one-component liquid near liquid–vapor coexistence. For curved interfaces, the analysis considers two local formulations of the same capillary-chemical balance, in excess pressures and in relative density deviations. For weakly compressible liquids in the regime emphasized here, the adopted asymmetric density-based formulation is the practically relevant one, with finite-curvature effects entering through vapor supersaturation under capillary equilibrium. At coexistence, the planar-limit value of the same Tolman length reduces to a combination of the liquid isothermal compressibility and its pressure derivative, which can be recast as a bulk fluctuation-response observable of the homogeneous liquid in the isothermal–isobaric ensemble. In this representation, the planar-limit coefficient is determined by second and third central moments of the volume distribution, equivalently by the pressure response of the relative fluctuation width. For water, homogeneous (N, P, T) simulations of the extended simple point charge and TIP4P/2005 water models sample the bulk liquid, not an explicit liquid–vapor interface, and yield estimates near −0.7 Å at 300 K. An independent evaluation based on the IAPWS-IF97 industrial formulation gives −0.713 ± 0.004 Å at the same coexistence state and predicts a weakly nonmonotonic temperature dependence along coexistence. Beyond water, the framework applies to other one-component liquids in regimes where an accurate thermal equation of state or sufficiently converged bulk volume statistics is available.

Interplay of ion availability and mobility in the loss of cation selectivity for CaCl2 in negatively charged nanopores: Molecular dynamics using scaled-charge models

Ion transport through charged nanopores is commonly interpreted in terms of the electrical double layer structure, leading to the expectation of cation-selective conduction in negatively charged pores. This picture can break down for multivalent electrolytes, where strong ion–surface correlations modify transport behavior. Here, we study NaCl and CaCl2 conduction through negatively charged silica nanopores using atomistic molecular dynamics simulations with scaled-charge (and also full-charge) ion models. By separating concentration, ci(r), and velocity, vi(r), contributions to the radial particle current density, ji(r) = ci(r)vi(r), we connect static adsorption to dynamic perm-selectivity. We show that strongly adsorbed, but immobilized Ca2+ ions and the low availability of Cl− ions in the surface layer near the charged wall make the contribution of this layer to the total conduction (surface conduction) small. It is the bulk-like electrolyte in the middle of the pore whose contribution (volume conduction) dominates the selectivity behavior of the pore (bulk-like or even slightly anion selective). Although this qualitative mechanism is robust, its detailed manifestation depends sensitively on the balance of ion–surface and ion–water interactions encoded in the force field.

Charge regulation and orientation dictate protein uptake into polyelectrolyte brushes

The phenomenon of charge regulation is of central importance in the interaction of many proteins with soft, electrically charged environments. Here, we used coarse-grained simulations to study the interaction of a globular protein—represented as a quadrupolar, charge-regulating nanoparticle—with a weak polyelectrolyte brush. Our simulations show that a quadrupolar nanoparticle interacting with a brush exhibits multistep complexation, producing double reionization jumps and distinct regimes of charge regulation as the nanoparticle penetrates the brush. In particular, strong local electrostatic fields induced by direct complexation with polymer strands yield nanoparticle charge states that decidedly differ from mean-field predictions based on the local pH alone. Moreover, we show that the nanoparticle orientation becomes a key degree of freedom governing the complexation: quadrupolar symmetry leads to angular locking near the brush surface, resulting in intricate orientational complexation pathways and characteristic kinks in the free-energy. All of these features represent beyond-mean-field coupling effects that arise from strongly localized charge clusters and cannot be described by simple multipole expansions or Poisson–Boltzmann approaches. Overall, our results highlight how higher-order charge asymmetries can profoundly influence the adsorption landscape and underscore the need to go beyond dipolar models when modeling realistic protein–brush interactions.

MixPI: Mixed-time slicing path integral software for quantized molecular dynamics simulations

We introduce the MixPI software to implement path integral molecular dynamics (PIMD) simulations for the study of condensed phase systems where nuclear quantum effects (NQEs) are important. In contrast to existing PIMD simulation software, MixPI enables the implementation of mixed quantum–classical path integral simulations where only a subset of system degrees of freedom (dofs) are treated quantum mechanically in an extended phase space while the remaining dofs are described classically. We expect this software to be particularly useful for simulations of electron and proton transfer in condensed phase systems, as well as for the study of biological and material systems where only a handful of dofs contribute significantly to the observed NQEs. We demonstrate the use of MixPI in two different systems. The first is a simple water model where we implement a set of mixed quantum–classical simulations to compute average energy and radial distribution functions. We use these simulations to benchmark the effectiveness of MixPI and to demonstrate how it enables systematic investigation into the origin of observed NQEs. We then compute radial distribution functions for a system where MixPI is essential: a solvated metal (M2+) cation described using an explicit quantized electron localized on an M3+ ion in water.

On the subtleties of cluster construction when defining crystalline nuclei in atomistic simulations

Molecular dynamics is routinely used to investigate crystal nucleation rates via computer simulations. According to classical nucleation theory, the size of the largest cluster should be the best approximation of the reaction coordinate. In Lennard-Jones melts, the sixth-order ten Wolde criterion [ten Wolde et al., Faraday Disc. 104, 93–110 (1996)] is often used to determine particles within solid environments, which are then grouped together based on proximity to define solid clusters. However, the resulting descriptor can sometimes poorly represent the nucleation process. Here, we investigate the effect of cluster construction methods on observed committor behavior. In the first part of the paper, we construct clusters based on (i) proximity only or (ii) proximity and the presence of an oriented “bond” between particles. In the second part of the paper, we vary the internal cutoffs used to compute the relevant order parameters. We find that, although a cluster construction method can have a large effect on the scale of a single nucleus, aggregate properties over ensembles of nuclei remain similar. In contrast, varying internal cutoffs can have a significant effect on both physical and committor properties. The results from both investigations support using a reaction coordinate of crystallinity times the size of the largest cluster rather than the size of the largest cluster alone.

Quasistatic optical modulation of Fowler–Nordheim field emission

We investigate the quasistatic modulation of Fowler–Nordheim-type field emission by an external optical field. When the characteristic tunneling time is much shorter than the optical period, the emission process is governed by the instantaneous local electric field, and the tunneling barrier can be modulated without direct photon absorption. Even a moderate optical field produces an exponential variation in the emission current due to the strong sensitivity of tunneling to the local field amplitude. This effect is further enhanced in nanoscale emitters by local field concentration. Order-of-magnitude estimates indicate that realistic parameters can yield substantial modulation of the emission current. The proposed mechanism provides a contribution to optical control of electron emission and may be relevant for ultrafast electron sources and nanoscale vacuum electronic devices.

Improved <i>ab initio</i> molecular dynamics–based vibrational spectroscopy for indirect hard modeling for bulk-phase vibrational spectroscopy using vibrational scaling and sampling diagnostics

Ab initio molecular dynamics (AIMD)-derived vibrational spectra provide a promising route toward calibration-free quantitative spectroscopy when combined with indirect hard modeling (IHM). Reliability of AIMD-based spectra for bulk-phase can be compromised by incomplete sampling, electronic-structure errors, and frequency shifts relative to experiment. In this work, an improved AIMD–IHM framework is presented that addresses these limitations through benchmarking comparison of the BLYP and B3LYP/ADMM functional methods to assess their relative accuracy, cluster-resolved sampling analysis based on hydrogen-bond kinetics, and a gas-phase-anchored vibrational frequency scaling strategy. The methodology is demonstrated for aqueous acetic acid, a strongly hydrogen-bonded system characterized by transient molecular associations and proton-sharing motifs. Raman spectra generated from bulk-phase AIMD simulations using BLYP and B3LYP/ADMM are benchmarked against experiment, revealing that the computationally efficient BLYP functional outperforms B3LYP/ADMM in reproducing experimental vibrational frequencies, with a root mean square error (RMSE) of 91 cm−1 compared to 155 cm−1 for the volumetric fraction of 0.2. A region-specific scaling procedure derived from gas-phase data significantly reduces the RMSE of BLYP-based bulk-phase spectra. Hydrogen-bond cluster analysis via reactive-flux indicates that the AIMD trajectories are sufficiently sampled for all relevant molecular motifs and provide quantitative evidence that the spectra are unlikely to be biased by undersampling. When integrated into IHM, the scaled AIMD-derived spectra determine experimental mixture compositions with an RMSE of 0.021 without any experimental calibration, representing an improvement over unscaled spectra, which showed an RMSE of 0.034. The proposed framework enhances the predictive accuracy of AIMD–IHM and extends its applicability to strongly interacting liquid systems.

Survodutide Once Weekly for the Treatment of Adults with Obesity

Efficient domain wall propagation across magnetic nanopatches

Magnetic domain walls are integral to logic, memory, and sensing technologies based on magnetic nanowires, including envisioned three-dimensional structures. We fabricate an interconnection of thin-film nanowires made of different materials with nanometer patching accuracy. Through micromagnetic simulations, we identify the critical parameters for achieving domain wall propagation across patched nanowires. The wire-to-wire domain wall propagation is analyzed by operando magneto-optical microscopy combined with simultaneous giant magnetoresistive characterization. Reliable propagation of magnetic domain walls in and across connected ferromagnetic nanowires in a rotating magnetic field is achieved. This is an essential step to the performance, reliability, and functionality of three-dimensional magnetic domain wall-based sensor devices. Our findings enable new strategies for designing nanoscale devices and further push the limits of miniaturization.

Highly localized water librational transitions as sensitive far-infrared spectroscopic observables for hydrogen-bonded ether and amine monohydrates

A combined mid-IR and Raman jet investigation of strongly hydrogen-bonded monohydrates of tertiary amines [Lwin et al., Phys. Chem. Chem. Phys. 27, 5808–5820 (2025)] recently reported strong anharmonic vibrational resonances. These resonances involve the spectrally redshifted and strongly IR-active hydrogen-bonded O–H stretching fundamental (OHb) of H2O and several overtone and combination states involving quanta of both intramolecular and intermolecular modes, blurring the suitability of the conventional OHb fundamentals as reliable empirical indicators of the intermolecular hydrogen bond strengths. It is shown that these universal anharmonic vibrational resonances are also observed for hydrogen-bonded monohydrates of both primary and secondary amines. The present work demonstrates that isolated vibrational transitions associated with large-amplitude intermolecular out-of-plane H2O librational motion prove to be alternative robust resonance-free far-IR spectroscopic observables that correlate strongly with intermolecular hydrogen bond strength across an extended series of ether and amine monohydrates. The observed H2O librational spectral signatures are compared with a comprehensive local energy decomposition analysis of the total interaction energies predicted at the DLPNO-CCSD(T)/aug-cc-pV5Z level. The combined results show that the librational transition energies are strongly correlated with the total non-dispersive energy contributions to the directional local hydrogen bond interactions across both classes of monohydrates and to a lesser extent correlated with the additional non-directional, long-range London dispersion forces introduced by bulky alkyl substituents.

Parameterizing DFT+ <i>U</i> corrections for III–V semiconductor alloys

(InxGa1−x)(As1−ySby) alloys are key materials for short-wave infrared (SWIR) sensors and related optoelectronic devices, where accurate band structure parameters are required for predictive TCAD simulations. Building on a previously proposed Bayesian Optimization approach for calibrating Hubbard parameters for crystals [Yu et al., njp Comput. Mater. 6, 180 (2020)], we develop a DFT+U framework in which Hubbard-U parameters on the III–V p states are calibrated to experimental alloy bandgaps and hybrid-functional reference band structures using Bayesian optimization. These parameters are then transferred to ternary alloys via a composition-dependent interpolation scheme applied to special quasi-random supercells. Using this calibrated approach, we obtain bandgap bowing parameters and effective masses for the four ternary subsystems of the (InxGa1−x)(As1−ySby) alloy in good agreement with experimental data and empirical bowing models. The same calculations provide the composition dependence of the EL and EX conduction band valleys, yielding a consistent ab initio set of band parameters across the relevant alloy space. These results provide device-ready input for TCAD simulations of SWIR detectors based on (InxGa1−x)(As1−ySby) and more generally illustrate how Bayesian calibration of DFT+U can be used to parameterize band structures in complex III–V alloys.

Rethinking Charge Transport and Recombination in Donor‐Diluted Organic Solar Cells

ABSTRACT We systematically investigate PM6:Y12 bulk‐heterojunction solar cells with donor fractions ranging from 1% to 45%, linking morphology, charge transport, and recombination to device performance. Complementary structural and spectroscopic methods reveal that a percolating PM6 network forms even at below 5% donor content, with lamellar stacking and vertical composition gradients that do not hinder the charge extraction. The reduction of the effective active layer conductivity toward low donor fractions obeys a three‐dimensional percolation model, indicating that charge transport is governed by network topology rather without a pronounced percolation threshold. A transition from nongeminate Langevin recombination to a dispersive Smoluchowski‐type loss occurs below 5% donor fraction. The latter regime is also nongeminate, i.e., pertains to recombination of the total charge carrier density. Correspondingly, we observe that the Langevin reduction in the higher donor fractions – mostly dominated by redissociation of electron–hole pairs after encounter – changes toward low donor fractions: in these cases, the nongeminate loss rate exceeds the prediction of the Langevin model. This regime coincides with increasing transport resistance due to topology‐limited hole conduction, leading to reduced fill factors despite a high retained charge‐generation efficiency. Our results demonstrate that strong donor dilution preserves photogeneration if a continuous donor network is maintained, and unveil how topology‐controlled transport and non‐Langevin recombination jointly define the performance limits of donor‐diluted organic solar blends.

A CPD-enabled low-scaling environment solver in a coupled cluster based static quantum embedding theory

We incorporate a canonical polyadic decomposition (CPD)-based low-level solver as a means to accelerate the environment-level solver for the recently developed Møller–Plesset Coupled-Cluster (MPCC) embedding framework. Using CPD, we both factorize the three dominant order-three density-fitting two-electron integral (DF TEI) tensors and develop a novel formulation that reduces the storage complexity of the low-level solver from O(N3) to O(NR), where R is the CPD rank, and the computational scaling of the most time-consuming contractions from O(N4) to O(NR2). We provide benchmarks on representative chemical environments, namely water clusters (H2O)n with n = 1 to 6 and linear alkane chains CnH2n+2 with n = 1 to 6. For both test sets, using the CPD-compressed DF TEI tensors reproduces the DF reference convergence behavior of the low-level solver, the subsequent high-level step, and the fully self-consistent MPCC iterations, while introducing only small, rank-controlled shifts in absolute energies. At a fixed tolerance in the absolute MPCC energy, the CP ranks required for these tensor approximations increase linearly with system size. Chemically relevant energy differences are likewise preserved, as demonstrated for water-cluster dissociation energies and in a proof-of-concept embedding calculation of methane in a four-water cluster.

Atomic-scale friction, thermal transport, and dislocation evolution in Fe–C alloy cutting with micro-textured CBN tools: A molecular dynamics study

Molecular dynamics simulations were conducted to investigate interfacial friction and plastic deformation during nanometric cutting of Fe–C alloys with micro-textured cubic boron nitride tools. A three-dimensional cutting model was established, including a conventional chamfered tool, a micro-textured tool, and micro-textured tools filled with graphene, carbon nanotubes, and molybdenum disulfide. The introduction of micro-textures alters the tool–chip contact configuration and reduces interfacial shear resistance, leading to a 22.3% decrease in steady-state tangential force and a reduction in friction coefficient from 2.19 to 1.59. Solid lubricant filling further regulates interfacial sliding and energy dissipation, with graphene showing the most significant effect. Dislocation analysis indicates that the plastic deformation of body-centered cubic Fe is dominated by 1/2〈111〉 dislocations. The presence of micro-textures and graphene suppresses the dislocation activity in the primary shear zone, thereby modifying the local plastic flow and interfacial friction behavior.