Search Results (326)

The teaching of chaos and nonlinear dynamics remains a significant challenge in physics education, as these concepts are often introduced through abstract mathematical models that are difficult to visualize. In this work, we propose an experimental approach based on electro-optics in nematic liquid crystals as an effective and accessible platform for teaching these phenomena. In particular, the system exhibits a transition from ordered convective patterns to strongly disordered turbulent regimes, which can be directly observed in real time using simple optical techniques. This experimental framework enables students to explore key concepts of nonlinear physics, including instability thresholds, pattern formation, and the emergence of complex dynamical behavior. The transition occurs through the nucleation and growth of turbulent domains, facilitating the understanding of nonequilibrium dynamics. From a pedagogical perspective, the proposed experiment combines strong visual impact with experimental controllability and accessibility, making it suitable for undergraduate students in physics, mathematics, and engineering. Furthermore, the integration of AI-assisted analysis provides students with an accessible framework to process experimental data, identify dynamical regimes, and explore complex systems through novel data-driven methodologies. Full article

In most cases, columbite-supergroup minerals are characterized by partial ordering of cations, which makes their identification based only on chemical composition and powder diffraction data difficult. Columbite-supergroup minerals with partially ordered cations were studied by means of electron microprobe analyses, powder and single-crystal X-ray diffraction, including crystal structure refinement in ixiolite-type and wolframine-type models. The samples originate from the Sakhanaiskiy granite massif, Eastern Siberia, Russia, (Sample 1) and from the Heftetjern pegmatite, Telemark, Norway (Sample 2). Their representative empirical formulae are (Fe²⁺_0.81Mn²⁺_0.53)_Σ1.34Fe³⁺_0.07(Ti_0.23Zr_0.11Sn_0.02)_Σ0.36(Nb_1.45Ta_0.26)_Σ1.71W_0.52O₈ (Sample 1) and (Mn²⁺_0.28Fe²⁺_0.25)_Σ0.53Sc_1.08(Sn_0.32Ti_0.04)_Σ0.36(Ta_1.41Nb_0.52)_Σ1.93W_0.10O₈ (Sample 2). Based on these data and the results of the crystal structure refinement, the studied samples can be considered as columbite-supergroup minerals in which cations are partially ordered in accordance with the wolframite mechanism. An approach is suggested according to which the degree of cation ordering in such columbite-supergroup minerals can be estimated based on the electron contents refined for different sites in a monoclinic model. According to this criterion, the degree of cation ordering of Samples 1 and 2 is 91% and 26%, respectively. Despite a significant degree of cation disordering, transition from the wolframite to ixiolite model results in a significant enhancement of the R-factor of the structure refinement (from 0.0365 to 0.0764 and from 0.0207 to 0.0610, respectively). Full article

The structural and electrical transport properties of brucite [Mg(OH)₂] were investigated by virtue of in situ Raman spectroscopy and alternating-current impedance spectroscopy under conditions of 0.5–20.2 GPa, 298–873 K, and different hydrostatic environments using a diamond anvil cell (DAC). Under the non-hydrostatic condition, the emergence of new Raman peaks and discontinuities in Raman shifts, FWHMs, as well as electrical conductivity well disclosed a hydrogen-disordering structural phase transition in brucite from the ordered ($P\overline{3}m1$ symmetry)–disordered ($P\overline{3}$ symmetry) structure at 5.7 GPa. Under hydrostatic condition, this transformation occurs at a lower pressure of 3.6 GPa using the 4:1 methanol–ethanol mixture (ME) as the pressure-transmitting medium (PTM), which can be attributed to the influence of deviatoric stress within the sample chamber. The reversibility of this transformation is confirmed by the recovery of Raman peaks and electrical conductivity upon decompression. Furthermore, the high-temperature and high-pressure electrical conductivity results clearly revealed a negative Clapeyron slope for the hydrogen-disordering transformation in brucite, and the corresponding high P–T phase diagram was established for the first time at pressures up to 7.0 GPa and temperatures up to 873 K, which can be expressed as $P \left(\mathrm{GPa}\right) = 8.664 (\pm 1.511) - 0.008 (\pm 0.002) T \left(\mathrm{K}\right)$. These results provide direct experimental constraints on the high-pressure phase stability and structural phase transition of brucite and offer an important reference for understanding the behavior of other hydroxide minerals under extreme conditions. Full article

Deposits of insoluble protein plaques, which are mostly composed of fibrils from disease-specific amyloid proteins, are histological markers of various human disorders. These range from non-neuropathic amyloidosis such as light chain amyloidosis or type II diabetes to well-known neuro-degenerative diseases such as Alzheimer’s Disease and Parkinson’s Disease. There are indications that these types of fibrillar suprastructures display biological activity distinct from the individual fibrils they are composed of. Yet, little is known about the mechanisms underlying the assembly of fibrillar suprastructures. An understanding of secondary fibril self-assembly into mesoscopic and macroscopic suprastructures is also critical for their application as novel biomaterial. The paucity of experimental data and theoretical models on fibrillar supra-assembly likely relates to the experimental and conceptual challenges in following this type of assembly on multiple length- and timescales, and in characterizing the distinct morphologies formed. Here, we report that the amyloid dye thioflavin T (ThT) is augmented during self-assembly of isolated lysozyme fibrils. We provide evidence that this augmentation of ThT fluorescence results from the unquenching of fibril-bound ThT during fibril binding. Combining ThT fluorescence, optical density, and fluorescence quenching kinetics with optical and electron microscopy, we propose that fibril self-assembly is driven by a transition from reaction-limited ordered assembly to diffusion-limited random cross-linking of fibrils. Full article

Alzheimer’s disease (AD) remains an incurable neurodegenerative disorder. The concept of theranostics—combining diagnostic and therapeutic functions within a single nanoplatform—has been explored for over a decade. Despite a growing number of publications, no theranostic system has yet reached clinical application for AD. This critical review analyzes the fundamental conceptual contradictions that hinder the clinical translation of theranostic nanoplatforms for AD and identifies alternative strategies where nanotechnology may still be beneficial. The review presents key aspects essential for understanding theranostics challenges: AD molecular targets, analysis of existing nanoplatforms, identification of three inherent conceptual conflicts, and viable alternative approaches. Our analysis reveals three core conceptual conflicts: the pharmacokinetic conflict, where diagnostics demand rapid accumulation and clearance while therapy requires prolonged retention—exacerbated by minimal brain delivery (1–2% ID/g) and peripheral toxicity risks; the dose conflict, characterized by orders-of-magnitude disparities between diagnostic and therapeutic dosing, rarely quantified for identical particles; and the temporal conflict, pitting one-time diagnostics against chronic therapy needs, as long-persisting particles generate irremovable brain background signals. We further identify a pervasive methodological trap: predominant focus on mature β-amyloid (Aβ) fibrils overlooks soluble oligomers as the primary toxic species. We conclude by proposing viable alternatives: preclinical intervention for time-limited “hit-and-clear” applications; coordinated theranostic monitoring with separate diagnostics/therapy; theranostic pairs using ligand-matched, function-optimized particles; and external stimuli for temporal function separation. A practical roadmap guides the transition from conceptual demonstrations to clinical translation. Addressing these contradictions can transform theranostics from elegant chemical constructs into clinically meaningful AD tools. Full article

Chain topology offers a chemistry-preserving route to tune block copolymer (BCP) self-assembly by modifying intrachain correlations and relaxation pathways without changing monomer interactions. Here, we perform a unit-matched comparison of four lamella-forming AB architectures reconstructed from an identical constitutive diblock unit ($N_0$): a linear diblock (DB), a linear multiblock (MB), a comb-like architecture (CB), and a star-like architecture (SB). Using dynamical density functional theory (DDFT), we quantify topology-dependent bulk ordering thresholds and show that architectural reconfiguration systematically stabilizes the ordered phase, reducing the order–disorder transition relative to DB (MB/CB/SB $\approx 0.793/0.762/0.752$ of the diblock value), in semi-quantitative agreement with random phase approximation (RPA) spinodal trends. We also compare topology-dependent directed self-assembly in a common trench geometry under matched reduced quench depth $\Delta \left(\chi N_0\right)=\chi N_0-{\left(\chi N_0\right)}_{\mathrm{ODT}}$, thereby isolating kinetic differences at comparable thermodynamic distance from bulk ordering. A Fourier-based alignment order parameter $\alpha \left(t\right)$ reveals sigmoidal alignment kinetics over decades in time and is well captured by a logistic form in $lnt$, enabling compact descriptors ($t_{50}$, $t_{90}$, and a steepness parameter k) that separate alignment onset from late-stage defect annihilation, while selective sidewalls robustly template sidewall-parallel lamellae across all topologies, the late-stage kinetics remain strongly connectivity dependent and can exhibit long-tailed completion associated with slow late-stage defect annihilation. These results demonstrate a dual role of topology in DSA: lowering the segregation strength required for bulk ordering while reshaping defect-mediated alignment pathways under confinement. Full article

High-velocity fluid flow in porous media frequently exhibits non-Darcy behavior, where inertial losses lead to nonlinear pressure gradient velocity behavior. Predicting the Forchheimer coefficient β remains challenging because β varies sensitively with pore geometry and is often not constrained by porosity and permeability alone. This study develops a structure-based method to estimate β using intrinsic descriptors obtained from the Darcy regime flow characterization and image-based geometry analysis. A set of two-dimensional granular porous media was generated with controlled variations in porosity, particle size distribution, and grain size variability. Single phase simulations are simulated with a body-force multiple-relaxation-time lattice Boltzmann method. The transition from Darcy flow to non-Darcy flow is identified from the velocity and pressure gradient response, and β is determined by fitting the inertial flow regime. Two tortuosity responses were observed. In uniform media, hydraulic tortuosity remained nearly constant in the Darcy regime and then gradually decreased. In disordered media, hydraulic tortuosity first increased with the onset of recirculation and then decreased as dominant flow paths became stable. Based on these results, a dimensionless inertial factor was correlated with porosity, intrinsic hydraulic tortuosity, and a pore structure index derived from specific surface area and hydraulic pore size. The resulting model predicts β from permeability and structural descriptors. The resulting correlation provides β estimates from Darcy permeability and geometry descriptors. Validation with quasi-two-dimensional microfluidic pillar array data showed that the model captured both the magnitude and relative ordering of β for the tested geometries. The proposed framework should be regarded as a proof of concept for idealized granular porous media and quasi-two-dimensional structured systems. Full article

The quantum Mpemba effect (QME) describes the counterintuitive phenomenon where a system initially further from equilibrium relaxes faster than one closer to it. Specifically, the QME associated with symmetry restoration has been extensively investigated across integrable, ergodic, and disordered localized systems. However, its fate in disorder-free ergodicity-breaking settings, such as the Stark many-body localized (Stark-MBL) phase, remains an open question. Here, we explore the dynamics of local $U\left(1\right)$ symmetry restoration in a Stark-MBL XXZ spin-$\frac{1}{2}$ chain, using the Rényi-2 entanglement asymmetry (EA) as a probe. Using an analytical operator-string expansion supported by numerical simulations, we demonstrate that the QME transitions from an initial-state-dependent anomaly in the ergodic phase to a universal feature in the Stark-MBL regime. Moreover, the Mpemba time scales exponentially with the subsystem size, even in the absence of global transport, and is governed by high-order off-resonant processes. We attribute this robust inversion to a Stark-induced hierarchy of relaxation channels that fundamentally constrains the effective Hilbert space dimension. The findings pave the way for utilizing tunable potentials to engineer and control anomalous relaxation timescales in quantum technologies without reliance on quenched disorder. Full article

Murunskite (K₂FeCu₃S₄) is a layered sulfosalt chalcogenide that occupies a unique position between the cuprate and iron pnictide families: it shares electronic characteristics with the former and adopts the crystal structure of the latter. Despite a completely random distribution of magnetic Fe within a nonmagnetic Cu matrix, murunskite exhibits a well-defined quarter-zone antiferromagnetic transition at 97 K and complete orbital order below 30 K. These findings reveal the unexpected emergence of long-range order in a high-entropy-like environment. This inherent robustness to site disorder in a layered structure makes murunskite a paradigmatic system for further studies. Here, we investigate doping strategies in murunskite to assess how its electronic and magnetic properties can be tuned. Using melt-growth techniques, we achieve substitutions at the magnetic metal site (Fe), spacer cation (K), and sulfur ligand (S), which significantly influence transport and magnetic properties. In addition, we use ionic-liquid gating on the parent compound and observe a gate-dependent suppression of resistivity, confirming the potential for electrostatic control over transport. Our results demonstrate the chemical and electronic plasticity of murunskite, offering a valuable platform for co-engineering disorder, magnetism, and transport, and opening avenues to explore quantum phenomena in correlated and high-entropy materials. Full article

Periodic supercell lattice structures with elements of random polydispersity disorder were created to simulate the effect of randomization on photonic crystals using finite-difference time domain (FDTD) methods. As a key exemplar system, a three-dimensional “inverse opal” structure of a face-centered cubic lattice with air spheres in a silicon dielectric was simulated, with sphere radii within supercells following a randomized Gaussian distribution, with characteristic standard deviation and mean. A corresponding ordered lattice with a bandgap with magnitude 3.5% of the normalized frequency range was used as a direct control, with sphere radius 0.34 times the lattice constant a. For a range of standard deviations, up to 5.9% of the 0.34a mean, a Monte Carlo-style approach was adopted, with photonic band properties analyzed over a large number of repeat simulations to ensure statistical significance. The corresponding Gaussian distribution in the resultant photonic bandgap magnitudes is broadened with increasing polydispersity such that an evolving fraction of simulations no longer exhibits a non-zero bandgap. A characteristic pseudo-transition occurs at a standard deviation of approximately 4.1% of the 0.34a mean, above where the frequency of simulations still returning a finite bandgap rapidly diminishes. Some isolated configurations, with a high degree of uniqueness, can exhibit enhanced bandgap properties (greater than the 3.5% benchmark) despite considerable polydisperse disordering; we envisage that these findings point towards the use of engineered randomness in supercell systems to create desired photonic crystal properties and functionality, such as localization and photonic bandgaps. Full article

Use of the morphotropic phase boundary (MPB) is a promising approach to enhance the electrocaloric effect in ferroelectric polymers. This is usually achieved by a composition method, and polymer processing near the MPB to tune electrocaloric response has attracted little attention. Here, the relative stability between disordered 3/1-helix and ordered all-trans conformations is leveraged by uniaxial stretching to improve the electrocaloric effect in relaxor ferroelectric polymers under low electric fields. It is found that the stretching technique enables a considerably more enhanced electrocaloric response in polymer composition near the MPB at room temperature, compared with counterparts corresponding to the relaxor phase. The electrocaloric-induced temperature change is found to be 4.5 K under a low electric field of 50 MV m⁻¹ in stretched relaxor ferroelectric polymers at room temperature, corresponding to a 60% enhancement over pristine counterparts. This result highlights the critical role of polymer processing in optimizing electrocaloric properties, especially near the MPB, and this can be extended to improve other functionalities, such as piezoelectric response, in relaxor ferroelectric polymers. Full article

Coated tofu is prone to spoilage and degradation during processing, storage, and transportation. As the material basis for gel of coated tofu, proteins determine coated tofu’s unique qualities, such as its colour, flavour, and texture. This study aimed to investigate the changes in the quality of coated tofu and the physicochemical properties of its proteins during cold storage (4 °C and 10 °C, 14 days), as well as the intrinsic correlations between these variables. Quality deterioration and protein structural changes were significantly slower at 4 °C than at 10 °C, with lower temperature effectively delaying quality loss. The results indicated that as storage time increased, the freshness of coated tofu declined, its textural properties significantly deteriorated, and the protein gel network structure became impaired. Meanwhile, the proteins underwent significant oxidative denaturation, characterized by a decrease in the free thiol group content and an increase in surface hydrophobicity. The tertiary structure exhibited unfolding and disruption, while the secondary structure transitioned from an ordered to a disordered state. Specifically, the contents of α-helixes and β-sheets decreased significantly, reaching 34.96% and 8.68%, respectively, after 14 days of storage at 4 °C. In contrast, the contents of β-turns and random coils increased to 30.11% and 26.25%, respectively, under the same storage conditions. The subunit bands of the 11S and 7S proteins gradually weakened, and the protein structure tended to loosen. Correlation analysis revealed that the oxidative denaturation, structural depolymerization, and reaggregation of proteins were highly significantly correlated with the textural breakdown and colour deterioration of coated tofu, which together contributed to the quality degradation of coated tofu during cold storage. The findings of this study provide fundamental data and technical support for the development of cold storage methods for coated tofu. Full article

Self-organizing systems arise in complex biomechanical structures, human locomotion, and neural control hierarchies, yet quantitative methods for describing order formation and loss of stability remain limited. This study develops a mathematical framework for analyzing self-organization using entropy-based measures, indicators of chaotic dynamics, and network-theoretic structure. The approach (the LET framework) combines Lyapunov exponents with entropy families and graph metrics (algebraic connectivity, Load-Path Heterogeneity Index) to: (i) examine transitions between ordered and disordered states, (ii) assess sensitivity to perturbations, and (iii) characterize structural coherence in evolving cervical spine kinematics. Analytical models and computational validations are presented for cervical stability and post-operative Adjacent Segment Disease (ASD) using the Branney–Breen dataset. The findings indicate that entropy and chaos measures identify regime shifts and the emergence of a “stability corridor” more clearly than task-oriented indices, and provide finer resolution of dynamical variability within self-organizing processes. Network metrics complement these results by linking local segmental interactions to global structural fragility transfer. The study shows that entropy, chaos indicators, and network structure together form a consistent basis for describing self-organization in biomechanical systems, enabling quantitative comparison of dynamical regimes and improved interpretation of emergent pathological behavior. The approach utilizes a hybrid kinematic surrogate model to resolve passive and active components, bypassing direct force measurements by employing viscoelastic mechanotransduction principles. Full article

Mixed-anion silicate–phosphate oxysulfide glasses have attracted increasing interest due to their tunable thermal stability, electrical response, and potential use in functional glass and glass–ceramic materials. In this work, silicate–phosphate oxysulfide glasses in the SiO₂-P₂O₅-K₂O-MgO-SO₃-ZnO system were examined to determine how partial substitution of MgO with ZnO influenced their thermal and electrical properties under reducing conditions. Melting in a strongly reducing atmosphere predominantly converted sulfur to reduced sulfur species, producing mixed oxygen–sulfur glass networks. Differential scanning calorimetry (DSC) shows that ZnO substitution reduces the configurational heat capacity at the glass transition (ΔC_p) by up to ~40%, suppresses crystallization exotherms, and shifts crystallization onset temperatures by more than 100 °C toward higher values, indicating enhanced network rigidity. Potassium and magnesium K-edge X-ray absorption spectroscopy (XAS) revealed increased short-range ordering around Mg²⁺ in Zn-free glasses after heat treatment, whereas Zn-containing glasses remain more structurally disordered. Impedance spectroscopy demonstrated that ZnO-substituted glasses exhibit higher activation energies for electrical transport (≈0.9–1.0 eV) and lower AC conductivity compared to Zn-free compositions, reflecting restricted alkali-ion mobility. These results demonstrate that partial substitution of MgO with ZnO significantly enhances the thermal stability and electrical insulating behavior of reduced silicate–phosphate oxysulfide glasses, providing valuable structure–property insights for the design of thermally stable functional glasses and glass–ceramics. Full article

Background/Objectives: Interpreting missense variants in intrinsically disordered proteins (IDPs) remains a major challenge, as these proteins lack stable structure and are under-represented in experimental and clinical annotations. Variants occurring in IDPs are disproportionately classified as variants of uncertain significance (VUS), reflecting the absence of appropriate predictive tools rather than true biological neutrality. Here, we address this challenge using a curated dataset of neurodevelopmental disorder (NDD)-associated proteins. Methods: We integrated curated and predicted disorder annotations from DisProt and MobiDB to characterize the structural landscape of 339 NDD-associated proteins. To quantify a regional genetic constraint, we recalculated the Missense Tolerance Ratio (MTR) using a published framework adapted to the recent gnomAD release (v4.1.0). Integration with 33,124 ClinVar-reported missense variants revealed that, while mean constraint levels differ only modestly across structural states, ordered and structural transition regions show the strongest depletion of missense variation. Results: MTR identifies localized low-tolerance subregions within IDRs, indicating that these regions are not uniformly permissive and can harbor functionally essential elements. Conclusions: Overall, our results demonstrate that missense constraint in NDD proteins is highly localized and context-dependent, and that integrating high-quality disorder annotations with updated MTR profiles can improve the prioritization and interpretation of missense variants in IDRs and IDPs. Full article