Dynamic amplification of isolated shear walls: Insights from layered shell modeling

Metal ions play critical roles in chemical, biochemical, and materials systems. The discrete-continuum model has been widely used for modeling metal ions in the aqueous phase due to its excellent balance of accuracy and efficiency. Previously, we demonstrated that a discrete-continuum model combining B3LYP-D3/def2-QZVP for the first solvation shell with the SMD implicit solvent model for outer shells accurately predicts hydration free energies (HFEs) of divalent, trivalent, and tetravalent ions. However, those results relied on single optimized geometries. Here, we extend this approach by incorporating molecular dynamics (MD) simulations to enhance conformational sampling for nine metal ions with charges from +2 to +4: the alkaline earth metal ions (Be2+, Mg2+, Ca2+, Sr2+, Ba2+), Al3+, Ce3+, Zr4+, and Hf4+. MD trajectories were filtered through quantum mechanical geometry optimization to identify representative structures, from which Boltzmann-weighted HFE values were calculated. Our results reveal that larger alkaline earth metal ions access more local minima, with the number of representative structures increasing as surface charge density decreases. Remarkably, these local minima exhibit fundamentally different electronic structures and chemical bonding patterns, as revealed by ETS-NOCV analysis. For ions with van der Waals surface charge densities below 0.1 e/Å2, accounting for multiple minima through Boltzmann weighting substantially improves agreement between discrete-continuum predictions and experimental HFEs. We propose this threshold as a practical criterion for determining when enhanced sampling is necessary in discrete-continuum models. These findings establish that rigorous conformational sampling is essential for accurate HFE predictions of soft metal ions, while the single-frame protocol remains adequate for rigid ions with high surface charge densities.

Cast borosilicate glass offers significant architectural potential for external façades, but its large-scale use is limited by the absence of established design data and standardised verification methods. This paper presents a performance-based methodology for thick, undulating cast borosilicate glass panels laminated to borosilicate float glass. Project-specific testing was undertaken to determine density, elastic modulus, thermal expansion and bending strength. The strength data were assessed using Weibull statistical methods, comparing EN, ASTM and weighted least-squares regression approaches.A calibrated equivalent-thickness method was developed to translate scanned three-dimensional cast geometries into practical shell models for façade analysis. Structural verification considered self-weight, wind loading, support conditions, local bracket zones and laminated glass interaction. Thermal shock risk was assessed using measured optical properties, local climatic data, solar radiation modelling and façade-specific shading scenarios. The resulting temperature differentials were converted into thermal stresses and checked against probabilistically derived material capacities. The work demonstrates a repeatable framework for combining testing, probabilistic design, finite element calibration and environmental assessment in non-standard façades.

Finding prototypical species that expand the structural and electronic features of molecular clusters is of interest for expanding the understanding of well-defined structures with particular stability. Here, we investigate the Y@Cu15 binary cluster using a modified basin-hopping (MBH) structure search method, revealing a stable configuration with a yttrium atom encapsulated in a low-symmetry Cu15 cage exhibiting C2v geometry, displaying different surface faces. The interaction energy ensuring Y-Cu15 encapsulation amounts to -220.4 kcal mol-1, mainly driven from electrostatic and orbital contributions, with orbital interactions dominated by charge transfer from 5s-Y→Cu15 and "back-donation" from 4d-Y←Cu15 orbitals, resulting in a sizable net charge transfer of -6.0|e| to yttrium. This charge distribution creates electron-deficient Cu sites analogous to the σ-hole regions, suggesting catalytic potential. The electronic structure of the cluster follows the 1S21P61D10 superatomic shell model, fulfilling Hirsch's 2(N + 1)2 rule for spherical aromaticity. Through-space nuclear independent chemical shift (NICS) analysis confirmed the presence of a shielding cone characteristic of aromatic species, supported by electron density of delocalized bond (EDDBG) analysis, which showed extensive electron delocalization consistent with spherical aromaticity. These findings establish Y@Cu15 as a novel, medium-sized spherical aromatic superatomic cluster with promising reactive sites for catalysis, thereby expanding the understanding of superatomic cluster chemistry and encouraging further exploration of its reactivity and applications.

Analytical vibro-acoustic model of laminated spherical shell is developed in order to study the vibrational characteristics of human eyeball considering intraocular pressure (IOP) effect. Eyeball layers are assumed to be viscoelastic with frequency- and IOP-dependent properties, filled with compressible inviscid internal fluid. Love's first approximation theory, along with the method of stress function, is used to formulate the governing equations of motion for a laminated spherical shell. The wave equation models the internal acoustic domain, and fluid-solid interaction is accounted for by enforcing velocity and stress continuity condition at the interface. The coupled system frequency equations are derived using the modal expansion method in conjunction with the orthogonality property of mode shapes. The analytical results are validated with the available literature and compared with the finite element simulations. The effects of different parameters including elastic modulus, eyeball thickness and radius, IOP variation, and frequency- and pressure-dependent properties on natural frequencies and damping characteristics are studied. It is observed that multi-layer modelling reduces natural frequencies slightly, whereas incorporating frequency- and IOP-dependent viscoelastic properties significantly increase them, demonstrating the critical importance of viscoelastic modelling for accurate eyeball biomechanics.

We present the first direct measurement of the Z=6 shell gap in the neutron-rich ^{20}O nucleus. The one-proton removal transfer reaction ^{2}H(^{20}O,^{3}He)^{19}N has been studied using the ACTAR TPC setup at GANIL. The use of ACTAR TPC enabled the measurement of low-cross section proton-removal reactions while preserving resolution. Eight p-hole states with ℓ=1 were identified in ^{19}N accounting for total strengths of 86% and 72% of the 0p_{3/2} and 0p_{1/2} single-particle orbitals, respectively. The energies and spectroscopic factors of the measured states allowed to determine the proton spin-orbit splitting π0p_{3/2}-π0p_{1/2} in ^{20}O. The Z=6 shell gap has been established to be 5.30(14)MeV. These findings indicate a reduction of the Z=6 shell gap while adding neutrons to the sd-valence orbitals, consistent with the effects of the tensor force predicted by state-of-the-art shell model interaction SFO-tls while at variance with the emergence of a large Z=6 gap observed in other studies.

The proton-rich nucleus [Formula: see text]Sm has been studied up to high spin and the level scheme has been extended beyond the six transitions previously reported in the ground-state band. Levels beyond E[Formula: see text] = 4 MeV and up to I[Formula: see text] = (16[Formula: see text]) have been identified. The first nucleon alignment in the yrast positive-parity structure has been established at a rotational frequency of ≈ 0.30 MeV, and is attributed to the breaking of a h[Formula: see text] proton pair. A negative-parity structure with its bandhead at E[Formula: see text] = 2061 keV and I[Formula: see text] = (7[Formula: see text]) has been identified and is attributed to the excitation of protons in the h[Formula: see text] and g[Formula: see text] orbitals. Cranked shell model calculations using the Ultimate Cranker code with standard Nilsson parameters indicate a prolate deformed minimum which persists to high frequencies. The calculated proton alignment frequency is in good agreement with the experimental value, and the neutron crossing is expected at a significantly higher frequency on account of the N = 72 deformed subshell gap.

Autogenous bone (AB) is considered the gold standard for alveolar bone grafting, but its limitations have prompted the development of synthetic alternatives. The Shell technique provides a stable framework for bone augmentation. However, few studies have directly compared different graft materials under intraoral-like conditions, especially in mandibular models. This study aimed to quantitatively compare the osteogenic capacity of four graft materials-autogenous bone (AB), β-tricalcium phosphate (β-TCP), octacalcium phosphate collagen composite (OCPC), and atelocollagen absorbable sponge (AAS)-using a rat mandibular shell model that simulates intraoral conditions. Cortical bone blocks were harvested from the mandibular body of 36 male Wistar rats, and mandibular reconstruction was performed using the Shell technique with cortical bone plates. Four graft materials, particulate AB, β-tricalcium phosphate (β-TCP), octacalcium phosphate collagen composite (OCPC), and Atelocollagen Absorbable Sponge (AAS), were evaluated. Each postoperative cohort consisted of 12 rats in total (n = 3 per group × 4 groups), and histological and histomorphometric analyses were performed at 8, 12, and 16 weeks postoperatively. AB generated significantly more new bone than the other materials at all time points. OCPC induced moderate limited regeneration until later stages, while β-TCP and AAS resulted in limited bone growth. The mandibular model effectively simulated oral anatomy and provided reliable structural support throughout the procedure. AB showed better osteogenic capacity than synthetic and composite materials. Use of the mandibular Shell technique with a rat model of mandibular defects proved useful for evaluating bone grafts under clinically relevant conditions.

This study investigates the numerical analysis of masonry arch bridges, a process often challenged by various sources of uncertainty that can compromise the reliability of results. A streamlined approach is proposed through the calibration of a simplified finite element model. The San Marcello Pistoiese bridge (Italy) serves as a case study, benefiting from extensive prior documentation, including laboratory testing and dynamic identification, which enables the validation of numerical simulations against experimental data. Two models were developed: a detailed three-dimensional solid model and a simplified shell model. Both employ the Concrete Damage Plasticity (CDP) approach to capture non-linear behaviour, using a bilinear stress-strain relationship up to peak strength, followed by a post-peak softening response in accordance with the Model Code. The shell model was calibrated against the solid model based on modal characteristics and subsequently used for non-linear analyses. Results show that the reduced model effectively reproduces key aspects of the structural response - such as capacity curves and damage patterns - while requiring only 1/500 of the computational time, making it a practical tool for extensive parametric studies under uncertainty.

Abstract While flare-associated coronal mass ejections (CMEs) generally show a strong association between flare X-ray flux and CME kinematics, their volumetric evolution and its link to both kinematics and flare activity remain less explored. In this study, we investigate the volumetric and kinematic coevolution of 10 Earth-directed, flare-associated CMEs using multiviewpoint observations from Solar TErrestrial RElations Observatory (STEREO)-A, STEREO-B, and SOlar and Heliospheric Observatory. We perform 3D reconstructions of the CME flux ropes with the graduated cylindrical shell model and derive their geometrical parameters. We find that the total CME volume follows a power-law dependence on the leading edge height and that different structural components expand at different rates, with the ellipsoidal front expanding faster than the conical legs. Furthermore, the volumetric evolution follows a multiphase pattern: initial overexpansion, a gradual reduction in the expansion rate, and finally saturation at a higher heliocentric distance. This is similar to the well-established three-phase evolution of the CME kinematics. Notably, the second-order derivative of volume with time shows a strong temporal correlation with both CME acceleration and the GOES soft X-ray flux of the associated flare. This is the first study to report such a correspondence between volumetric evolution and flare timing, highlighting the role of flare energy release in governing CME expansion dynamics. Our findings motivate further studies into the coupling between magnetic reconnection and CME volumetric evolution in the corona.

Abstract Simulating physical systems with variational quantum algorithms is a well-studied approach, but it is challenging to implement in current devices due to demands in qubit number and circuit depth. However, limited knowledge of a system can reduce the cost of these algorithms. We demonstrate that the computational overhead in simulating many-body systems can be systematically decreased by leveraging the system’s symmetries, which guide the choice of iterative entanglement forging partitions aligned with the underlying entropy structure. To do so, we simulate a Fermi-Hubbard one-dimensional chain with a parametrized hopping term, as well as atomic nuclei $${}^{28}$$ 28 Ne and $${}^{60}$$ 60 Ti with the nuclear shell model. Within an adaptive variational quantum eigensolver setting, we propose an algorithm that employs partitions and subpartitions of the quantum circuit to reduce significantly the quantum resources compared to a fully-fledged simulation. Entropy-driven entanglement forging (EDEF) does not require access to the full statevector or exact entropies; in hardware it is implemented via standard EF expectation-reconstruction rules with crossed statistics, while statevector access is used here only as a classical simulation shortcut. We find that the maximum number of qubits can be reduced by up to a factor of four and we observe an order of magnitude decrease in the number of two-qubit gates compared to regular simulations. Our findings indicate that our method, entropy-driven entanglement forging, can be used to adjust quantum simulations to the limitations of noisy intermediate-scale quantum devices.

Based on the data recorded during the Parker Solar Probe mission, it can be suggested that there is no balance between kinetic and magnetic energy in the vicinity of the Sun. The spectra collected at different radial distances show an energy transfer from one component to another, followed by a change in inertial range slope and large-scale break shifted towards lower wave numbers. Using the shell (cascade) modeling approach, we attempt to explain and understand this observed spectra transformation, considering a free-decay turbulence process and modeling a simple transition to a quasistationary equilibrium between the magnetic and kinetic energies. Varying the parameters of turbulence mirror asymmetry (helicity), we numerically simulate changes in spectral indexes, large-scale shift position, and inertial range transformations, comparing our model results with spacecraft observations of solar wind turbulence. We present and discuss the chaotic nature of the spectral magnetic helicity distributions, as well as the fact that helicity can accumulate at large scales. The applicability of a simple magnetohydrodynamics shell model to repeat the key features of solar wind turbulence dynamics offers wide possibilities for its further use.

Murine thrombus organization limits access to high platelet activation states while supporting platelet recruitment.

Steel Thin-walled Beams with restrained flanges are commonly used in structural systems where partial or full lateral and rotational restraints may occur, such as in steel–concrete composite beams used in slabs and in highway bridge decks. While these restraints enhance global stability, they can also trigger complex buckling behaviours. One such mode is lateral-distortional buckling (LDB), which arises when the tension flange is restrained against both lateral translation and rotation, leading to web distortion and twisting of the compression flange during buckling. Numerous studies have shown that existing empirical methods for predicting the elastic critical moment of LDB lack sufficient accuracy. This paper presents a numerical approach for estimating the elastic lateral and distortional buckling capacity of thin-walled I-beams under uniformly distributed loading. The developed method, referred to as Distortional Beam Formulations (DBF13), offers an efficient and practical modeling framework that incorporates second-order shell kinematics to accurately capture LDB behaviour. To validate the proposed formulation, Shell-element models were used in case studies and compared against existing experimental and analytical data. A total of 3540 analyses were conducted on doubly-symmetric and mono-symmetric I-section models under various boundary conditions to evaluate DBF13 across different buckling scenarios. Additionally, the effects of the cross-section classification, beam span, flange and web slenderness ratios were examined. The case study results underscore the reliability of DBF13 in predicting the Lateral Torsional Buckling as well as the Lateral Distortional Buckling behaviour. In the eigenvalue predictions, DBF13 has shown an average difference of less than 11% compared to shell model results.

Study of the Punching Shear Resistance of RC Slabs with Pyramid Shell Model

Trehalose is widely recognized for stabilising proteins under conditions that promote dehydration, denaturation, or loss of function, yet its underlying mechanisms remain elusive. We examine myoglobin in trehalose solutions of two concentrations to evaluate whether trehalose forms a protective sugar shell beyond the hydration layer-a concept suggested by molecular dynamics simulations but not experimentally verified. Using neutron diffraction, we demonstrate that myoglobin remains almost fully hydrated in both systems, even at high trehalose concentrations. To probe myoglobin-trehalose interactions, we constructed two starting models: (i) trehalose molecules dispersed randomly in the solvent and (ii) a pre-assembled trehalose shell positioned adjacent to the protein surface. After refinement, both models converged with experimental data in the Q range (1-30 Å-1), despite resulting in markedly different final configurations, although the protein was preferentially hydrated by water in both cases. However, the shell model yields substantially higher low-Q intensities (0.03-0.5 Å-1), inconsistent with the experimental data, demonstrating that trehalose does not form a pronounced layer outside the hydration shell. Residue-resolved analysis further confirms that there are almost no direct trehalose-protein interactions for hydrophilic or hydrophobic amino acids. In addition, quasielastic neutron scattering reveals slower dynamics for all components in the concentrated system. Furthermore, the protein motions are considerably slower in the three-component systems compared to those in a trehalose-free binary solution. This finding shows the significance of the dynamically stabilising effect of trehalose on proteins in cryoprotective and pharmaceutical applications.

Due to the increase in the use of Steel Framing systems on buildings in Brazil, as well as the lack of studies on the behavior of some of its elements under dead and live forces, this work was formulated to find the relation between numerical and experimental models, and defining relations between them for a better understanding of these systems in service. For this purpose, experimental tests were conducted on light steel frame (LSF) beam trusses used on decks and combined dead and live loads pre-established in standards. The experimental system was developed, consisting of three Light Steel Frame trusses, an OSB board, and a water tank. Seeking the correct load distribution, the water tank was filled, and the water level was controlled; in addition, the volume water flow rate was also measured with a flowmeter. Thus, only the central truss had its deformation results measured using digital comparators. Moreover, alongside the experimental analysis, numeric models of beams and shells were held on Finite Element Method (FEM), operated on the commercial software ANSYS Workbench. The deemed models were of three-dimensional shell geometry and two-dimensional beam geometry with and without eccentricity. Furthermore, the results were evaluated after the analysis, providing recommendations for modeling Light Steel Frame deck trusses. In conclusion, the geometric model, recommended for modulation and simulation, is the bi-dimensional beam model showing the eccentricity of web ligations. Additionally, this model has accurate results and is similar to the actual behavior of the trusses studied.

Neutron–proton pairing correlations occupy a central position in nuclear structure physics. While like–particle pairing between neutrons or protons in the isovector (T = 1) channel is firmly established and accounts for many systematic features of nuclear spectra, the role of neutron–proton correlations, particularly in the isoscalar (T = 0) channel, remains a subject of ongoing debate in both experiment and theory. In this review we examine the theoretical foundations and current understanding of neutron–proton pairing, beginning with the conceptual distinctions among several phenomena that are often conflated in the literature: the residual neutron–proton interaction, isovector pairing correlations, and possible isoscalar pairing condensates. We discuss how these different forms of correlation emerge in the shell–model framework and how they are represented in BCS mean–field approaches. Special attention is given to the pedagogical aspects of single-j pairing models, algebraic approaches, as well as the shell-model-like exact pairing diagonalization algorithms, which provide valuable benchmarks for understanding the limitations of mean–field descriptions and the interplay between isovector and isoscalar pairing channels. We also review experimental signatures that have been proposed as evidence for neutron–proton pairing, including spectroscopic patterns in N ≈ Z nuclei, mass systematics, and transfer reactions, and discuss the extent to which these observations support or challenge current theoretical interpretations. The review highlights both the progress achieved in clarifying the mechanisms of neutron–proton correlations and the major open questions that remain, particularly regarding the existence and manifestation of collective T = 0 pairing modes in finite nuclei. Finally, a practical computational scheme for the exact diagonalization of neutron–proton pairing is presented.

Modeling propagation of ultrahigh-energy cosmic rays using the input from the configuration interaction shell model

We investigate the Reynolds-number dependence of the maximal Lyapunov exponent in fully developed turbulence, which quantifies the rate of chaotic divergence of nearby velocity fields. Using decorrelators constructed from infinitesimally perturbed flows, we find that the Lyapunov exponent scales with Reynolds number as λ∼Re^{α}, with an exponent α=0.59±0.04 exceeding the classical mean-field prediction. By explicitly separating the nonlinear strain and viscous contributions to decorrelator growth, we show that this departure is associated by intermittent fluctuations of the strain-rate tensor, which dominate the short-time growth of the infinitesimal perturbations over viscous damping. Direct numerical simulations of the Navier-Stokes equations and complementary tests using a reduced shell model yield consistent scaling behavior, indicating robustness within the frameworks considered. Our results show that the dynamical origin of chaotic divergence in turbulence is closely linked to intermittent strain-rate fluctuations.