Search Results (1,184)

Artificial intelligence has greatly accelerated the design and screening of metal–organic materials, particularly for crystalline systems with well-defined topologies and increasingly standardized structural databases. However, this success has also created a structure-centric design paradigm that is less suitable for metal–organic systems whose functions are governed by process history, interfacial assembly, and dynamic coordination rather than by a single idealized lattice. This Perspective proposes that artificial intelligence (AI)-guided design of metal–organic materials should expand beyond crystalline metal–organic frameworks (MOFs) to encompass a broader structural continuum, ranging from long-range ordered frameworks to dynamic, non-periodic coordination networks. Metal–polyphenol networks (MPNs) are used here as an experimentally tractable example within a broader family of structurally dynamic metal–organic materials, as they arise from coordination interactions between metal ions and polyphenolic ligands, generally lack long-range crystallographic periodicity, and exhibit functions that are governed by interfacial assembly, environmental responsiveness, and pathway-dependent structural evolution. These features challenge conventional descriptor design and database-driven prediction, but also create opportunities for AI approaches that are process-aware, interface-sensitive, and function-oriented. By placing MOFs and MPNs within a unified framework of structural order, this Perspective outlines how machine learning, multimodal characterization, active learning, and closed-loop experimentation could expand metal–organic materials design from topology prediction toward dynamic network optimization. Full article

Properties of defects in crystals composed of soft particles, such as colloids, differ markedly from those in metals. In this work, dislocation reactions in a bundle of carbon nanotubes (CNTs) are investigated using relaxational molecular dynamics. The problem is reduced to a two-dimensional model, where the strain state of the CNT bundle is fully determined by the cross-sectional shapes of the nanotubes arranged in a close-packed triangular lattice. A pair of edge dislocations with opposite topological charges is introduced into an uniaxially compressed bundle, and their relaxational dynamics are analyzed as a function of the distance d between the parallel planes along which the dislocations glide. When the dislocations move in the same plane (d = 0), they annihilate, restoring a defect-free structure. For negative distances (d < 0), their interaction results in the formation of a vacancy (d = −1), a bivacancy (d = −2), extended voidions (d = −3, −4), or dislocation dipoles (d < −4). In contrast to metals, vacancy clusters containing more than two missing particles in CNT bundles relax into extended voidions. For positive distances (d > 0), the dislocation reaction generates interstitial-type defects in the form of crowdions, which at sufficiently large separations (d > 4) can also be interpreted as dislocation dipoles. In most cases, except for d = 0 and d = 1, dislocation glide enables complete relaxation of the initial shear strain, even in the presence of defects. However, for d = 0 and d = 1, dislocation annihilation or immobilization limits plastic deformation, resulting in only partial stress relaxation. The observed effects are due to the elliptization of the cross-sections of soft carbon nanotubes in the cores of defects. These findings highlight significant differences in defect behavior between crystals of deformable particles and conventional metallic systems. Full article

Nonlinear kickers (NLKs) enable off-axis injection in ultralow-emittance storage rings by providing a strong kick to the injected beam while remaining nearly transparent to the stored beam. In hybrid schemes, a conventional four-kicker bump defines the injected trajectory, and the NLK reduces the first-turn action under constrained beam offset and optics conditions. Effective operation additionally requires stable and reproducible first-turn injection trajectories. We develop a compact action–angle framework that expresses NLK dynamics in terms of Courant–Snyder invariants and yields an analytical bound on achievable action reduction. This formulation provides direct design rules for NLK placement, phase advance, injected-beam offset, and kicker field profile. Within this framework, we identify the 8-wire NLK as a practical baseline and extend its design by relaxing the square-geometry constraint, enabling inward shifting of the off-axis field peak while preserving on-axis field and gradient cancellation. Application to the NSLS-II lattice shows how aperture, pulsed-power, and mechanical constraints combine to determine a coupled design solution. Multi-turn tracking confirms that candidate NLK locations maintain sufficient stay-clear (aperture-clearance) margin, while the optimized wire geometry reduces the required current and Lorentz force load. The results establish a unified approach for NLK-assisted injection design and provide a practical pathway for upgrades in diffraction-limited storage rings. Full article

This study investigates the effect of dilute organic acid treatment on the structural, textural, electronic, and catalytic properties of layered La–Sr–Fe–O Ruddlesden–Popper (R–P) oxides using XRD, TEM, BET, Mössbauer spectroscopy, XPS, H₂-TPR, C₂H₆-TPR and catalytic testing. XRD and TEM confirm that the overall layered Ruddlesden–Popper structure is preserved after acid treatment and during catalysis, with minor changes in phase composition, including a decrease in the n = 1 phase and a relative increase in the n = 2 phase. BET analysis shows increased specific surface area and pore volume, forming a more accessible mesoporous structure that is retained under reaction conditions. Mössbauer spectroscopy and XPS reveal an increased Fe⁴⁺ fraction and formation of hydroxylated and carbonated surface species stabilizing active Fe sites. During catalysis, a dynamic Fe³⁺/Fe⁴⁺ redox cycle occurs, along with surface restructuring and involvement of non-lattice oxygen, while the bulk electronic structure remains largely unchanged. Catalytic tests show improved activity, with a 40–60 °C reduction in operating temperature for all acid-treated samples, independent of acid type. This enhancement is mainly attributed to surface-related modifications, including removal of surface Sr-containing species, improved surface accessibility, and enhanced mass transport, while the overall R–P structural remains preserved. Full article

A novel modified generalized Riccati equation mapping neural network-based approach is the basic theme of this study by exploring the nonlinear dynamical characteristics of the the strain wave model’s soliton solutions, which govern wave propagation in micro structured solids. Strain waves are particularly intriguing, since they preserve their form and speed throughout transmission. The nonlinear dynamical behaviors of strain waves may be modeled by partial differential equations in micro structured materials. In the realm of micro structured solids, there exists a class of phenomena that are referred to as micro strain waves. These waves arise in solids possessing intricate internal architectures, including periodic lattices, precisely engineered metamaterials Understanding these waves is key to designing more complex materials and new acoustic technologies. The activation function and the weight function of the neural network are assigned to each input layer, hidden layer and output layer and the neural network itself is a multi-layer computational network. Using the structure of the neural network, every neuron in the first hidden layer is given solutions to the Riccati equation, and the new highly expressive trial functions are generated in a systematic way. In this way, a large variety of exact soliton solutions are obtained, such as bright, dark, kink, and combined solitons as well as periodic and hyperbolic wave profiles. The influence of the essential physical and mathematical parameters is explored systematically using three-dimensional, two-dimensional and contour visualizations, which illustrate how parameter variations lead to changes in the amplitude, shape and stability of the wave structures. The solutions presented reveal the dynamic properties of micro strain solitons which leads to new avenues of investigation in the study of related nonlinear phenomena in micro structured solids. In a broader context, our results highlight the great potential of analytical techniques using neural networks as a powerful and versatile toolset to study complex nonlinear wave models within the applied sciences from acoustics to photonics to smart materials engineering. Full article

Two-dimensional (2D) materials have emerged as a key platform for next-generation electronics due to their atomic thickness and tunable properties. Iron disulfide (FeS₂), known as pyrite, with a bandgap of ~0.95 eV, is suitable for solar energy applications. However, its performance is limited by defects in bulk crystals. Reducing FeS₂ to a single layer eliminates bulk defects and enables strain engineering of the bandgap. In this study, First-principles density functional theory (DFT) calculations are performed using the CASTEP code and the PBEsol functional to examine the structural, electronic, and optical properties of a distorted 1T′-phase FeS₂ monolayer. Full geometry optimization yields lattice parameters a′ = 17.594 Å, b′ = 3.20231 Å, c′ = 5.28091 Å, and Fe–S bond angles of ~75.8° and ~98.2°, confirming symmetry-breaking distortion. The monolayer is dynamically stable, showing no imaginary modes in the phonon dispersion, and remains structurally intact up to 1000 K in molecular dynamics simulations. The unstrained system has an indirect bandgap of 0.70 eV, with the valence band maximum at the Γ point (dominated by S-p states) and conduction band minimum near the X point (Fe-d states). Under mechanical strain (±4%), the bandgap decreases significantly: from 0.70 eV to 0.44 eV under +4% tensile strain along the y-axis, and to 0.53 eV under −4% compressive strain. Biaxial strain causes weaker modulation, reducing the gap to 0.66 eV (+4%) and 0.62 eV (−4%). Optical absorption exceeds 10⁴ cm⁻¹ for photon energies above the bandgap, with tensile strain causing redshifts and compressive strain inducing blueshifts. These findings demonstrate that 2D FeS₂ is mechanically robust, electronically tunable, and optically active, making it a promising candidate material for flexible strain sensors and photovoltaic devices. This work is intended to motivate and inform future synthesis efforts. Full article

High-entropy alloys (HEAs), composed of five or more principal elements in near-equimolar ratios, have emerged as a groundbreaking class of materials for next-generation flexible electronics. This review systematically examines the unique potential of HEAs as sensing materials, moving beyond their traditional role as structural components. We first elucidate the fundamental mechanisms—core effects including lattice distortion, sluggish diffusion, and the cocktail effect—that endow HEAs with an exceptional synergy of high strength, good ductility, tunable electrical resistivity, and superior electrocatalytic activity. Subsequently, we critically analyze the state-of-the-art strategies for processing HEA-based micro/nano structures, including mechanical alloying, wet-chemical synthesis, and non-equilibrium deposition techniques, with an emphasis on their compatibility with flexible substrates. The core of the review categorizes and discusses the latest advances in HEA-based flexible sensors for strain/stress, gas, and electrochemical (e.g., glucose, biomarkers, heavy metals) detection, highlighting the structure–property–performance relationships. Representative studies have demonstrated that HEA flexible strain sensors achieve a temperature coefficient of resistance as low as 45.59 ppm/K with no signal drift over 6000 stretching cycles; room-temperature hydrogen sensors reach a detection limit down to 31 ppb with a response time of 19 s; and non-enzymatic glucose sensors deliver a sensitivity up to 3043 μA·mM⁻¹·cm⁻². Finally, we summarize the key challenges—such as manufacturing scalability, long-term stability under dynamic deformation, and cost-effectiveness—and provide a forward-looking perspective on promising research directions, including high-throughput compositional screening, multi-functional sensor arrays, and the integration of machine learning for rational material design. Full article

The Kelvin lattice is a fundamental model to study the dynamical properties of metamaterials. This paper is devoted to quantitatively characterizing a nanopteron solution, which is a superposition of a central solitary wave and trailing oscillations, in a Kelvin lattice. We have illustrated that each nanopteron solution possesses a Stokes curve. We have also shown that the appearance of trailing oscillations in nanopteron solutions is a result of Stokes phenomena, which emerges when the Stokes curve is crossed in the complex plane. By employing an exponential asymptotic analysis, we have obtained analytically the relation between the amplitude of the trailing oscillations and the system parameters. Our theoretical predictions show good agreement with numerical simulations for a wide range of system parameters. Full article

This work reports the colloidal synthesis of Nd-containing mixed-halide perovskite quantum dots described as CsPb(Nd)Br_3−γCl_γ, followed by post-synthetic surface modification with an acid-activated amino-functional siloxane. This notation is used deliberately because the available FE-SEM, DLS, EDX, and optical data confirm the formation of an Nd-containing mixed-halide colloidal perovskite system, but do not provide direct crystallographic proof of substitutional Nd³⁺ incorporation at the Pb²⁺ B-site. The obtained dispersions show stable blue emission with a maximum at about 458 nm, a photoluminescence quantum yield of about 56%, an essentially invariant emission maximum when the excitation wavelength is varied from 300 to 390 nm, and monoexponential decay kinetics with a characteristic lifetime of 6.67 ± 0.97 ns. Field-emission scanning electron microscopy combined with morphometric analysis of at least 150 particles indicates a nanoscale size distribution with an average equivalent diameter of 8.8 nm, a median of 7.3 nm, and 93.25% of particles smaller than 25 nm. Dynamic light scattering confirms a narrow hydrodynamic size distribution in the 7–9 nm range and a low polydispersity index. Elemental mapping by EDX confirms the co-presence of Cs, Pb, Br, Cl, and Nd in the analyzed particles. The observed blue shift is discussed in terms of the combined effect of chloride incorporation, nanoscale size, possible Nd-related perturbation of the local electronic/defect structure, and reduced non-radiative losses after surface passivation. No definitive crystallographic assignment of Nd to a specific lattice site is claimed; the composition is therefore treated as nominal, and the structural interpretation remains provisional pending XRD/XPS or related studies. Full article

This research investigates a vertically structured Ge-on-Si avalanche photodetector (APD) fabricated in a separate absorption, charge, and multiplication configuration. The application of ramp gating enables reverse bias beyond the punch-through voltage, allowing the device to operate in linear avalanche mode. A significant dark avalanche current is observed under steady conditions, exhibiting linear multiplication approximately proportional to the input gating and thermal generation rate. Notably, this linear behavior persists even at voltages beyond the Geiger mode. The observed results are attributed to Ge/Si interface traps caused by the 4.18% lattice mismatch and deep-level traps introduced during fabrication. Under 1550 nm short-wave infrared normal-incidence pulsed illumination, the device exhibits negative differential resistance, attributed to illumination-induced self-quenching of electric field in multiplication region and modification of the barrier at the Ge/Si interface. A light-induced slow transient decrease in the absolute dark-state current is followed by a sustained inverse quenching effect, restoring the large dark-state current. These findings offer insights into the dynamic behavior of Ge-on-Si APDs, with potential implications for advanced optoelectronic applications. Full article

We review the structure of pseudoscalar mesons within an algebraic model formulated in the light-front framework. The approach provides a unified description of leading-twist parton distribution amplitudes, light-front wave functions, generalized parton distributions, parton distribution functions, elastic electromagnetic form factors, charge radii, and impact-parameter space distributions, all obtained from the same underlying Bethe–Salpeter wave-function representation. The analysis covers light mesons $(\pi ,K)$, the mixed $\eta$–${\eta }^{\prime }$ system, heavy–light states $(D,D_s,B,B_s,B_c)$, and heavy quarkonia $({\eta }_c,{\eta }_b)$, thereby enabling a systematic study of quark-mass effects, flavor-symmetry breaking, and the transition from emergent hadronic mass to heavy-quark dynamics. Where available, results are compared with experimental measurements, functional methods such as lattice-QCD calculations and Dyson–Schwinger Equation formalism, and other phenomenological approaches. The algebraic model thus offers a transparent, symmetry-preserving, and analytically tractable framework for connecting the longitudinal, transverse-momentum, and spatial structure of pseudoscalar mesons across all quark-mass regimes. Full article

There is increasing interest in structured layered double hydroxide (LDH)-based catalysts because they combine tunable acid–base/redox chemistry with reactor architectures that can reduce diffusion lengths, improve heat management, and lower pressure-drop penalties. This review evaluates LDH, LDH-derived oxide (LDO/MMO), reduced metal/LDO, reconstructed hydroxide-rich, and mixed dynamic states integrated into honeycomb monoliths, open-cell foams, meshes/felts, thin films, washcoats, coated plates, microchannels, capillaries, and additively manufactured lattices. To move beyond descriptive comparison, the literature is assessed using unified evaluation dimensions: operative active state, support architecture, coating/integration route, active-phase loading, coating thickness and uniformity, reactor-volume-normalized productivity or STY, ΔP/L, axial/radial thermal gradients, time-on-stream, coating loss, regeneration recovery, and pilot-readiness. Representative benchmarks illustrate both the promise and reporting gaps of the field: NiFe-LDH-derived monoliths for CO₂ methanation have reached ~70% CO₂ conversion at 300 °C with >90% CH₄ selectivity and only 0.7% post-test mass loss; NiFe-LDH/iron-foam monoliths retained 85% ozone conversion after 168 h; high-entropy LDH-derived oxides showed T50/T90 values of 246/254 °C for toluene oxidation; and Au/LDH capillary films achieved 31.9% glycerol carbonate yield and 3.78 g h⁻¹ g⁻¹ productivity. The strongest current cases are pollution abatement and CO₂ methanation, whereas biomass upgrading, fine-chemical flow, high-entropy coatings, and photo/electrocatalytic films require deeper module-level validation. Overall, structured LDH catalysts should be treated as coupled chemistry–coating–reactor systems whose performance must be judged simultaneously by activity, accessible catalyst inventory, transport efficiency, pressure drop, thermal profile, durability, regeneration, and manufacturability. Full article

Non-Hermitian photonic lattices offer unconventional control over light evolution owing to modal non-orthogonality and the resulting non-normal dynamical response. In this work, we show that a uniform passive waveguide lattice with dissipation confined to one or a few sites near an edge can exhibit an algebraic(nearly linear) decay of optical power—an absorption law forbidden in orthogonal (normal-mode) dissipative systems, where any superposition of eigenmodes yields purely multi-exponential attenuation. We demonstrate that algebraic absorption arises when the input excitation is appropriately tailored to exploit non-orthogonal modal interference, effectively channeling energy toward the dissipative boundary. In particular, under the condition of coherent perfect absorption (CPA) associated with a spectral singularity of the semi-infinite lattice, nearly complete light absorption accompanied by algebraic decay of the optical power can be achieved. Starting from the minimal configuration of a single lossy edge site, we derive compact analytical expressions for the dynamics and identify the conditions under which linear-like absorption emerges. We then extend the analysis to multiple edge-proximal lossy sites. Our results show that simple dissipative photonic lattices, when driven by suitably prepared input states, enable robust sculpting of absorption laws through non-normal dynamics, providing a new route to programmable attenuation. Full article

Additively manufactured cellular architectures frequently exhibit brittle failure under impact due to layer-induced stress concentrations. Through the programming of architectural and material design, specifically combining Fused Deposition Modeling (FDM) lattice topology with hyperelastic polyurea infiltration, this study achieves active control over the macroscopic transition from catastrophic structural fragmentation to stable progressive collapse. To evaluate this, auxetic and honeycomb specimens printed with ABS and glass-fiber-reinforced polyamide (PA-GF) were evaluated in unreinforced and polyurea-infiltrated states under quasi-static compression, three-point bending, and Charpy impact loading. Results show that the compressive response depends primarily on cellular topology; the pure auxetic (A-A) configuration provided the highest stiffness and energy absorption. Polyurea infiltration did not significantly alter elastic stiffness but increased post-yield stability, leading to a 96.6% elastic recovery in PA-GF A-A structures. In flexure, the base polymer governed stiffness, with ABS structures measuring 68% stiffer than PA-GF. Unreinforced ABS achieved 34% higher specific energy absorption (SEA) than PA-GF under compression, with the A-H topology maximizing SEA. Under dynamic impact, PA-GF absorbed an average of 70% more energy than ABS, and the H-A configuration recorded the highest impact resistance. The addition of polyurea shifted the failure mode from brittle fragmentation to stable elastomeric deformation, increasing absorbed impact energy by 52% for ABS and over 30% for PA-GF, preventing catastrophic structural failure. Integrating topological sequencing with elastomeric confinement provides a direct method to control energy dissipation and damage tolerance in 3D-printed cellular composites. Full article

In this work, we develop machine-learned moment tensor potentials (MTPs) to simulate the static and dynamic structural properties in Al_xGa_1−xN and related materials. The potentials are trained on DFT-calculated data for forces, stresses, and energies obtained from random atomic displacements and cell deformations. MTP-calculated physical properties, including lattice parameters and elastic constants, thermal expansion, harmonic and anharmonic vibrational properties, and the thermal conductivity, are benchmarked against first-principles results and experimental data. The comparisons testify to the very high accuracy achieved by the machine-learned potentials despite the massively reduced computational effort. Additionally, the impact of various aspects of the MTP training procedure is examined. Full article