Stereochemical elucidation of synthetic and natural compounds is a rate-determining step in the structure determination process. In the present work, we introduce a method called Chirality In Silico Structure Elucidation (CiSE), which employs 1JCC coupling constants to determine the correct stereochemistry of natural products. To determine the correct stereochemistry, the proposed method assigns a probability to all possible structures of a compound in question. For calculating these probabilities, the errors between the experimental and density functional theory (DFT) computed 1JCC couplings of a large number of compounds are fitted into Student's t-distribution, from which statistical parameters such as mean, standard deviation, and degrees of freedom are determined. Afterward, the probabilities for all possible candidate structures are calculated using Bayes's theorem, with the correctly assigned stereoisomer typically exhibiting a probability exceeding 95%.

A relocated augmented coprime array for balancing low mutual coupling and high degrees of freedom

Circularly polarized luminescence (CPL) provides an additional degree of freedom for light manipulation beyond intensity and wavelength and is essential for advanced photonic technologies. Chiral hybrid metal halides (HMHs) have recently emerged as promising CPL-active materials. However, the simultaneous realization of high efficiency near-infrared (NIR) emission and strong CPL remains challenging. Here, we report an enantiomeric pair of zero-dimensional hybrid copper bromides, (18C6@S/R-CHEA)2Cu4Br6 (abbreviated as S/R-CHEACuBr, 18C6 = 18-crown-6, S/R-CHEA = (S/R)-1-cyclohexylethanamine), in which protonated S/R-CHEA+ is coordinated with 18C6 to form the bulky umbrella-type supramolecular cations. Such unique cations effectively isolate the inorganic [Cu4Br6]2- emissive clusters and induce pronounced distortions of inorganic clusters. As a result, the obtained materials show strong circularly polarized near-infrared (CP-NIR) emission with photoluminescence quantum yields exceeding 50% and a high dissymmetry factor up to 6.8 × 10-2. Furthermore, light-emitting diodes based on these materials exhibit high output power and distinct CP-NIR signals, offering new opportunities for NIR imaging and secure information technologies.

Outcomes of an Opt-Out Chlamydia Testing Program Across 21 Northern California Pediatric Clinics.

Altermagnetism, a newly discovered magnetic phase, blends the beneficial properties of ferromagnetism and antiferromagnetism, spurring extensive efforts to utilize it for spintronic applications. The unique transport properties, when transplanted to photonic systems, are anticipated to offer a new degree of freedom for controlling electromagnetic wave propagation, which alerts the study of altermagnetism in the photonic domain. Here, we show that altermagnetism can be mimicked using photonic crystals, demonstrating that the engineered photonic crystals can host spin space group symmetries through chiroptic media. Our approach allows for the creation of altermagnetic spin-split bands, and the corresponding transport properties provide an effective platform for circularly polarized light isolation without the need for geometrodynamic spin-orbit interaction. Beyond the concurrent solid-state materials, we anticipate our work to offer photonic crystals as a versatile platform to test altermagnetic spin-split band properties and inspire optical designs for photospintronic applications and unconventional even-parity wave pseudochirality.

Mapping reaction pathways on complex potential energy surfaces (PESs) and locating transition states (TSs) is often used for understanding chemical reaction mechanism(s). The nudged elastic band (NEB) method is widely used for this purpose, but it becomes computationally expensive for large systems due to the repeated evaluation of energies and forces. We present an active learning algorithm coupled with the nudged elastic band, AL-NEB, for efficient convergence to the TS. AL-NEB constructs a surrogate PES and actively selects training points in two phases: (a) Exploration-Exploitation and (b) Renunciation. Strategies have been introduced for making the algorithm efficient and stable. We show the efficacy of the algorithm on several 2D analytical potentials, HCN isomerization, keto-enol tautomerization, and high-dimensional heptamer island diffusion (up to 525 degrees of freedom). In all cases, AL-NEB locates the "exact" TS on the chosen model chemistry with an order-of-magnitude fewer force evaluations than the standard NEB, demonstrating its scalability and efficiency.

Purpose This study aims to address the challenges of robotic cloth folding, stemming from complex dynamics and high degrees of freedom. While existing learning-based approaches have shown promise, they often suffer from limited generalization across diverse fabrics and require extensive real-world data. To address this gap, we propose a perception-centric strategy introducing HrcbamFolding, a dual-arm system that leverages a deep network to directly map visual inputs to the key manipulation points required. This approach simplifies the complex problems of state estimation and motion planning into a structured keypoint detection task, effectively bypassing the need for explicit physical modeling of the fabric. Design/methodology/approach This study proposes HrcbamFolding, which combines a multiresolution neural network with a channel–spatial attention mechanism to spotlight task-critical fabric regions, thereby enhancing visual-perception accuracy and generalization across diverse materials. It further uses a grasp-pose prediction module that translates visual inputs directly into coordinated grasping and placement actions for each arm, which reduces motion-planning errors and improves execution efficiency. The framework is trained purely in simulation on rectangular fabrics before being assessed on three multistep folding benchmarks. Findings This study shows that in all three tasks, HrcbamFolding achieves greater execution efficiency than baseline methods. It also delivers higher folding accuracy in two tasks while maintaining competitive performance in the third. Despite being trained only on simulated rectangular cloth, the system generalizes well to real-world manipulation of nonrectangular garments such as T-shirts and shorts, requiring only minimal fine-tuning. The demonstration video is available at: https://www.youtube.com/@Jaui-g9j. Originality/value This study presents a practical dual-arm folding system featuring a novel perception architecture that yields both high accuracy and exceptional sample efficiency for sim-to-real transfer. By focusing on structural feature learning via multiresolution attention and direct action prediction, HrcbamFolding advances the state-of-the-art toward generalized and data-efficient robotic fabric manipulation, offering significant value for real-world automation.

Abstract We develop a strictly geometric reformulation of General Relativity (GR) in which a scalar clock field ϕ defines the spacetime foliation through its timelike gradient nµ = -∇µϕ/ -(∇ϕ) 2 . The field ϕ is not a new dynamical degree of freedom and does not enter the action; its sole role is to generate a covariant, hypersurface-orthogonal slicing that renders the ADM lapse, shift, and extrinsic curvature algebraic functionals of (gµν , ϕ).Starting from the pure Einstein-Hilbert action, we carry out a complete 3 + 1 decomposition adapted to the clock-field foliation and derive the Hamiltonian constraint, momentum constraint, and full constraint algebra. All coincide exactly with their canonical GR counterparts, confirming that the theory propagates only the two tensorial graviton modes and contains no additional scalar or vector excitations. The Einstein equations are recovered identically, the ADM algebra remains first class, and both cosmological dynamics and linear perturbations match those of standard GR.The novelty of the construction is conceptual rather than dynamical: ϕ provides a covariant, relational time variable that fixes the foliation non-perturbatively, offering a clean geometric notion of time for canonical quantization and Wheeler-DeWitt evolution. Because the framework introduces no new fields, couplings, or potentials, it avoids the instabilities and extra degrees of freedom typical of scalar-tensor or modified-gravity theories.This yields a mathematically consistent and fully covariant formulation of GR with an internally defined geometric clock, opening new directions for relational observables, deparametrized quantum gravity, and emergent-time frameworks.

Phase control is fundamental to acoustic wave manipulation. The propagation and resonant phases have been widely used to modulate acoustic waves. However, the real-space geometric phase, also known as the Pancharatnam-Berry (PB) phase, has remained elusive in acoustics, owing to the fact that airborne sounds are curl-free longitudinal waves lacking intrinsic polarization degrees of freedom. Here, we theoretically and experimentally demonstrate that the PB phase can emerge in inhomogeneous sound waves with polarization evolution of velocity field. Using surface sound waves as an example, we uncover the intriguing Janus property of the PB phase arising from spin-momentum locking, and experimentally demonstrate acoustic PB metasurfaces for versatile wavefront manipulation. We further extend the mechanism to free-space structured sound and realize acoustic q-plates for converting vortex topological charge through spin-orbit interaction. Our work uncovers a type of acoustic phase and provides a simple yet effective mechanism for structured sound manipulation, with promising applications in acoustic communications, imaging, and on-chip devices.

Electrochemical machining (ECM) offers precise shaping by material dissolution with negligible mechanical or thermal impact on the workpiece. Metal parts with three-dimensional shapes, such as freeform surfaces or additively manufactured parts, can be addressed by robots with up to six degrees of freedom without significant mechanical impacts on the end-effectors and robots. This study summarizes the state-of-the-art of the use of robots in ECM by assessing the relevant literature. Several investigations were found that implemented or conceptualized the use of robotic arms in ECM sinking, jet-ECM or wire ECM, mainly for effective utilization of the processes. This study includes results of pure ECM, as well as hybrid ECM processes and the use of robots considering their accuracy, degrees of freedom and their application potential. Special emphasis is given to the role of robots in improving machining accessibility and their usability for valuable components in the aerospace, biomedical, and tooling industries. Furthermore, the review provides insights into electrolyte delivery mechanisms and pump configurations that facilitate efficient process performance. Overall, the utilization of robots in ECM not only enhances the process flexibility and surface quality but also aligns well with the aim of intelligent, automated, and high-precision manufacturing.

Obstacle-avoidance risk threshold control and global discrete keypoint re-entry are critical factors influencing the smooth dynamic obstacle avoidance of unmanned vessels. For underactuated USVs, which operate in planar motion with three degrees of freedom (surge, sway, and yaw) but only two independent control inputs (surge velocity and yaw rate), this paper designs a layered obstacle-avoidance strategy featuring adaptive global path re-entry points, combined with short- and long-term obstacle trajectory prediction and risk perception. This method employs an Interactive Multiple Model (IMM) integrating Constant Velocity (CV), Constant Acceleration (CA), and Constant Turn Rate and Acceleration (CTRA) models to perform long-term spatiotemporal trajectory prediction for dynamic obstacles, constructing a spatiotemporal risk cost map. Long-term dynamic obstacle-avoidance trajectory planning is achieved through optimized adaptive global trajectory re-entry points and an improved A* algorithm. This long-term avoidance trajectory replaces the global path from the avoidance start to the re-entry point, providing a smooth, continuous long-term avoidance prediction. To ensure real-time collision avoidance effectiveness, an improved Dynamic Window Approach (DWA) algorithm uses the long-term avoidance trajectory as a foundation. It integrates the IMM’s short-term spatiotemporal obstacle trajectory prediction, sampling in the velocity and steering angle space to generate short-term avoidance control commands. Finally, the long-term and short-term obstacle-avoidance planning are executed in a receding-horizon manner, where the local DWA planner updates control inputs over a short rolling window without solving a full constrained optimization problem. This establishes a hierarchical avoidance strategy: long-term prediction enables smooth avoidance, while short-term prediction enables real-time avoidance, ensuring the continuity and timeliness of dynamic obstacle avoidance. Simulation results demonstrate that compared with traditional A* planning, the proposed risk-aware A* reduces cumulative collision risk by 62% and increases the minimum obstacle clearance distance by over 32.1%, while maintaining acceptable path length growth. This approach effectively reduces collision risks during navigation, enhances path smoothness, and improves navigation safety.

We predict a so-called axial Hall effect, a Berry-curvature-driven anomalous Hall response, in Lieb-lattice altermagnets. Using a tight-binding model, we reveal a hidden topological degree of freedom: the axial pseudospin. Breaking the double degeneracy of axial symmetry exposes this pseudospin, generating a substantial Berry curvature and pronounced intrinsic anomalous Hall conductivity. Subsequent first-principles calculations confirm the emergence of this effect in the family of strained ternary transition-metal dichalcogenides. Focusing on Mn2WS4, we demonstrate that the axial Hall effect essentially arises from the interplay between Dresselhaus spin-orbit coupling and the piezomagnetic response, resulting in highly localized and enhanced Berry curvature. Remarkably, the magnitude of this effect is significant and remains constant under varying strain, underscoring the topological nature of the axial degree of freedom. Beyond monolayers, this effect manifests as a distinctive thickness-dependent modulation of both anomalous and spin Hall responses in multilayer structures. These findings emphasize the critical role of spin-orbit coupling and noncollinear spin textures in altermagnets, an area that has received limited attention, and open new pathways for exploring and tuning intrinsic Hall phenomena and spintronic applications in topological altermagnets.

Abstract We present direct numerical simulations of a novel concept for a microscale wind turbine, inspired in the mechanics of the autorotation of winged seeds. In this nature-inspired concept, the turbine blades have two degrees of freedom: the pitch and the elevation (or coning) angles. These allow the blade to vary its attitude with respect to the incoming velocity seen by the blade (i.e., the tip-speed ratio, $$\lambda $$ λ ). In order to validate this new concept, we perform numerical simulations of the coupled fluid–solid problem, solving together the Navier–Stokes equations for the fluid and the Newton equations for the rigid body (i.e., the blade). We characterize a preliminary nature-inspired single-blade rotor over a range of operational conditions (including both uniform and turbulent inflows), demonstrating the ability of the novel rotor to extract power at a very low Reynolds number (i.e., $$\textrm{Re}=240$$ Re = 240 based on the blade’s chord and the freestream velocity), significantly changing its attitude in response to different braking torques and tip-speed ratios. The rotor achieves a peak power coefficient of $$C_{P,\max } = 0.026$$ C P , max = 0.026 at $$\lambda \approx 2.0$$ λ ≈ 2.0 . This peak value is unchanged between uniform and turbulence-perturbed inflows, demonstrating the robustness of the nature-inspired design. However, performance remains lower than that of fixed-blade configurations, showing that while the concept is feasible and stable, optimization of blade planform and mass distribution is essential to improve efficiency.

Piping systems must cope with the internal pressure of the fluid they carry. They are almost always well-designed for withstanding steady-flow pressures, but allowing for unsteady-flow pressures and for fatigue can be more challenging. Positive and negative gauge pressures induced by waterhammer waves are possibly the most extreme that piping is likely to face during its lifetime. It is widely accepted that this should be addressed by analyses during the design phase, but this is usually done under the assumption that consequential (non-hoop) structural movements do not affect the calculated pressures. However, the calculated pressures are used as input to the structural design. Commonly, attention focusses on static predictions of induced hoop stresses and on the risk of buckling, but attention sometimes has to be paid to dynamic responses. In these cases, the complexity of the structural analysis depends on the assumed degrees of freedom of possible movement, so it is desirable to avoid including unnecessary detail. The title of this paper poses one question that is frequently asked. However, the correct answer is not always obtained, partly because highly misleading answers were published in one early paper, the rebuttals to which were much less widely reported. The current contribution attempts to answer the question for both fixed and movable bends. Attention is paid to pressure transients arriving at bends from remote locations and potentially inducing pipe movement. Then, the opposite effect is considered, namely the generation of pressure transients by structural movements. To avoid distorting the picture by combining this with nominally unrelated causes, strong simplifications are made—e.g., disregarding all forms of energy dissipation.

We introduce twisted anisotropic homobilayers as a distinct class of moiré systems, characterized by a distinctive "magic angle," [Formula: see text], where the moiré unit cell collapses. Unlike conventional studies of moiré materials, which primarily focus on small lattice misalignments, we demonstrate that this moiré collapse occurs at large twist angles in generic twisted anisotropic homobilayers. The collapse angle, [Formula: see text], is likely to give rise quasi-crystal behavior as well as to the formation of strongly correlated states, that arise not from flat bands, but from the presence of ultra-anisotropic electronic states, where non-Fermi liquid phases can be stabilized. In this work, we develop a continuum model for electrons based on extensive ab initio calculations for twisted bilayer black phosphorus, enabling a detailed study of the emerging moiré collapse features in this prototypical system. We show that the (temperature) stability criterion for the emergence of (sliding) Luttinger liquids is generally met as the twist angle approaches [Formula: see text]. Furthermore, we explicitly formulate the collapsed single-particle one-dimensional (1D) continuum Hamiltonian and provide the fully interacting, Hamiltonian applicable at low doping levels. Our analysis reveals a rich landscape of multichannel Luttinger liquids, potentially enhanced by valley degrees of freedom at large twist angles.

Abstract We study time-evolving resonant states in an open double quantum-dot system, taking into account spin degrees of freedom as well as both on-dot and interdot Coulomb interactions. We exactly derived a non-Hermite effective Hamiltonian acting on the subspace of two quantum dots, where the non-Hermiticity arises from an effect of infinite external leads connected to the quantum dots. By diagonalizing the effective Hamiltonian, we identify four types of two-body resonant states. For the initial states of localized two electrons with opposite spins on the quantum dots, we exactly solve the time-dependent Schrödinger equation and obtain time-evolving two-body resonant states. The time-evolving resonant states are normalizable since their wave function grows exponentially only inside a finite space interval that expands in time with electron velocity. By using the exact solution, we analyze the survival and transition probabilities of localized two electrons on the quantum dots.

Modelling of nonadiabatic reactions for heterogeneous photocatalysis involving absorbates on metal nanoparticles provides insight for the interpretation of experiments. In this paper, photoinduced H2 dissociation in a Au6H2 model complex has been investigated using Time-Dependent Density Functional Theory (TDDFT), and with a decoherence corrected fewest switches surface hopping (DC-FSSH) approach that includes all degrees of freedom of the Au6H2 cluster in the photodynamics. The excited states of this cluster near the equilibrium geometry mostly involve weakly entangled combinations of transitions between occupied orbitals with 60% gold d-orbital character and unoccupied orbitals that are 95% sp, with little variation between different excited states for energies close to what is the Au plasmon energy for larger clusters. Both adiabatic and nonadiabatic process play significant roles in H-H bond dissociation, with adiabatic dissociation always being fast and nonadiabatic dissociation involving slow or fast mechanisms and little variation in the dissociation dynamics when different excited states are considered. In all cases both hydrogen atoms end up chemisorbed on the Au cluster, in contrast to earlier work which suggested that dissociation was dominated by one or both H atoms going to the gas phase. Most H-H bond dissociation reactions take place via the nonadiabatic pathway and leading to both hydrogens chemisorbed on the nearest Au atom, but others lead to H's on different Au atoms. H2 desorption from the Au6 cluster competes with hydrogen dissociation, and is always nonadiabatic for this model. Charge transfer between the adsorbed H2 molecule and the Au6 cluster is found to make a minor contribution to H-H dissociation. Instead, the calculations show that nonadiabatic transitions between metal localized states are dominant, and that the lowest excited metal-localized state adiabatically evolves into an H2 dissociative state. These calculations provide new insights to an important model system for plasmon mediated photocatalysis.

The advancement of nanophotonic devices is significantly dependent on achieving high-precision inverse design capabilities, which are critical for identifying optimal structural configurations that enable enhanced and multifunctional performances. The process of inverse design confronts a one-to-many relationship due to the complex mapping between optical performance and structure. Though several approaches, including tandem networks, mixture density networks (MDN), and conditional generative adversarial networks, have shown promising outcomes, they still face accuracy limitations when confronted with structures with higher degrees of freedom. Here, we propose a sampling-enhanced MDN called a mixture probability sampling network (MPSN), that outputs mixture Gaussian distributions (MGDs) of structural parameters through an end-to-end framework. The results of multiple samples drawn from the MGDs are fed into a pre-trained network, and the sample that minimizes the error relative to the real data is selected for network training. We benchmark the high performance in nanophotonics through the structural color design, achieving a high precision of up to 99.9% and a mean absolute error of less than 0.002. This work paves the way for resolving intricate inverse design problems in nanophotonics.

A single metal center that supports both the chirality and magnetism is a crucial design factor expected to achieve strong magneto-optical response, as it maximizes the coupling between magnetic and optical degrees of freedom. However, achieving such integration in molecular systems remains highly challenging. Here, we report a pair of chiral clusters, R/S-DyFe3, in which the magnetic DyIII ion simultaneously acts as the chiral and magnetic center within a propeller-like framework. Magneto-optical measurements reveal pronounced and fully reversible magnetic modulation circular dichroism (CD) signal of the NIR f-f transitions, with strong enhancement and clear signal inversion under ±1.6 T. Particularly, the field-dependent CD intensity corresponding to the 6H15/2 → 6F11/2 hypersensitive transition increases by approximately 40 times under an applied magnetic field compared to zero field. The exceptional responsiveness arises from Zeeman splitting and magnetic-field-induced mixing of 4f sublevels, which markedly amplify the magnetic circular dichroism (MCD) contribution within the overall CD signal. These findings provide the first chiral molecular demonstration of magnetic-field-controlled CD signal in a chiral cluster with structural centers that support both chirality and magnetism, offering crucial insights into designing chiroptical materials with magnetic field modulation.

Metal substrates suppress the intrinsic vibrational degrees of freedom of graphene nanoribbons (GNRs) through interfacial hybridization and damping, limiting access to their one-dimensional phonon physics. Here, we show that reducing ribbon-substrate coupling unlocks intrinsic phonon excitations in metal-supported GNRs. This is achieved by intercalating a self-limited, chemically inert bismuth monolayer beneath pregrown 7-armchair GNRs on Au(111), forming an ordered van der Waals interface that strongly suppresses interfacial damping while preserving ribbon continuity. Temperature-dependent Raman spectroscopy reveals the recovery of intrinsic phonon activity and pronounced mode-selective renormalizations, reflecting reduced substrate screening and strain relaxation. Scanning tunneling spectroscopy and first-principles calculations confirm a quasi-freestanding electronic structure arising from increased ribbon-substrate separation and strongly suppressed charge transfer. These results establish inert interface engineering as an effective route to access and control intrinsic phononic properties of one-dimensional carbon nanostructures directly on metal substrates.