Search Results (984)

Conducting polymer–metal nanocomposites are widely investigated as tunable photonic and optoelectronic media; however, reported property trends often remain empirical because electronic disorder at the absorption edge, refractive-index dispersion, free carrier dielectric response, and third-order nonlinearity are rarely quantified within a single, composition-controlled film series. This limitation is particularly relevant for electrochemically grown PANI coatings on transparent conductive substrates, where nanoparticle incorporation can simultaneously enhance polarization while introducing aggregation-driven heterogeneity. Here, Ag/PANI nanocomposite thin films were fabricated directly on indium tin oxide (ITO) by potentiostatic electrodeposition from an aniline/camphorsulfonic acid electrolyte containing controlled Ag nanoparticle loadings (5–15 wt.%). This study addresses the research gap by integrating complementary optical-disorder and dispersion formalisms with dielectric and nonlinear analyses to establish a composition structure optics map for device-relevant films. Ag incorporation narrows the indirect optical gap from 1.98 eV (PANI) to 1.81 eV (5 wt.%), 1.38 eV (10 wt.%), and 1.19 eV (15 wt.%), while markedly broadening the Urbach tail (0.377 eV → 1.28–1.64 eV at 5–10 wt.%). Wemple–DiDomenico modeling and Drude-type dielectric dispersion reveal strongly non-monotonic evolution of oscillator energetics and the carrier response, culminating in large bound-electron dielectric constants (ε_∞ up to 469.8) and plasma frequencies (ω_p up to 248 × 10¹² Hz) at 15 wt.% Ag. Third-order nonlinearity is substantially enhanced but composition-sensitive: χ³ increases from 6.73 × 10⁻⁹ esu (PANI) to ~7.6 × 10⁻⁸ esu at 5 and 15 wt.%, whereas the Kerr coefficient peaks at 25.91 × 10⁻⁷ esu for 5 wt.% and is suppressed at intermediate/high loading. These results demonstrate that the optimal nonlinear performance is governed by a disorder–dispersion balance and microstructure-dependent local-field effects rather than the Ag fraction alone. Full article

This study investigates the effects of hydration, temperature, and γ-irradiation on the structural, thermal, and mechanical properties of Lactoprene^® 7415, a linear block copolymer consisting of 74% lactide, 15% trimethylene carbonate, 11% ε-caprolactone repeating units, and 40 wt% β-TCP/Lactoprene^® 7415 composite. Techniques including static and dynamic mechanical testing or differential scanning calorimetry have evidenced structural changes resulting from irradiation- or water-induced crystallinity, crosslinking, chain scission or plasticization. Notably, hydration and physiological temperatures reduced the mechanical properties but conferred hyperelastic characteristics to the polymeric and composite samples. γ-irradiation was detrimental for the mechanical properties, except for those of the pure polymer in dry conditions. Our results evidence a complex interplay between the polymer, particles, temperature, hydration and water. Such observations could have implications in future designs and investigations of composite materials for scaffold-guided bone regeneration (SGBR), such as sterilization processes or minimally invasive surgery. Full article

The mode-locking mechanism of Kerr-lens mode-locked lasers is analyzed using the nonlinear ABCD matrix formalism. Our findings demonstrate that positioning the Kerr medium at the beam waist and operating the resonator near the stability boundary significantly enhances the nonlinear effect, thereby facilitating self-starting mode-locking without requiring any external initiation mechanisms. Full article

Platonia insignis Mart. (Clusiaceae) is a native fruit tree of great ecological and socioeconomic importance in the Brazilian Amazon and Cerrado. However, habitat loss is threatening its genetic variability. We investigated whether habitat fragmentation across the Amazon, Cerrado, and transition zones shapes the genetic diversity and population structure of five natural populations of P. insignis, using ISSR markers. Leaf samples from 13–15 individuals per population were collected, and DNA was extracted using the CTAB protocol. Twelve ISSR primers amplified 149 loci, used to estimate genetic parameters. AMOVA showed that 73.58% of genetic variation occurred within populations and 26.41% among populations (F_ST = 0.261). Amazonian populations exhibited the highest genetic diversity, while transition zone populations had the lowest values. The Cerrado population was genetically distinct and maintained moderate intrapopulation diversity. Bayesian clustering, PCoA, and UPGMA revealed three genetic groups corresponding to the sampled regions. Transitional populations showed high genetic admixture, indicating their role as potential corridors for gene flow. Our results highlight the need to preserve genetically diverse Amazonian populations, safeguard the Cerrado population as an evolutionarily significant unit, and maintain transitional populations to promote landscape connectivity. The study provides a genetic baseline to support conservation and management of P. insignis germplasm resources. Full article

We investigate the spin-charge-induced scalarization of Kerr–Newman (KN) black holes in the Einstein–Maxwell-scalar (EMS) theory with a scalar potential and positive coupling parameter. In the linearized theory, there exists a bound of $0<a<a_o$ with onset spin $a_c$ for the negative region signaling instability by analyzing the effective scalar mass term in the $\theta$-direction. Solving the (2 + 1)-dimensional evolution equation numerically, we find the region where the KN black hole becomes unstable, giving rise to scalarized KN black holes. The threshold curve for representing the boundary between stable and unstable KN black holes depends on charge Q, scalar mass $m_{\varphi }$, coupling parameter $\alpha$, and spin parameter a with upper bound $a^2\le M^2-Q^2$. Full article

In this work, we investigate the shadow properties of the Kerr–Newman–Anti-de Sitter black hole coupled to nonlinear electrodynamics. The shadow is constructed by employing the celestial coordinate approach for an observer located at a finite distance, which is required due to the non-asymptotically flat structure of the spacetime. The size, distortion, area, and oblateness of the shadow are analyzed in terms of the black hole parameters, namely, the spin, the effective charge, and the nonlinearity parameter. We show that the nonlinear electrodynamics significantly modifies the photon region and therefore changes the shadow observables, while the rotation mainly controls the deformation of the silhouette. We further confront the theoretical results with the Event Horizon Telescope observations of M87* and Sgr A* in order to constrain the parameter space of the model. The allowed ranges of the effective charge depend sensitively on the nonlinearity parameter, and the combination of both sources leads to tighter and physically more consistent bounds. In addition, we study the energy emission rate derived from the shadow radius and the Hawking temperature and discuss how it is affected by the rotation and the nonlinear electromagnetic field. Our analysis shows that the considered black hole solution provides a consistent extension of the Kerr geometry in a non-asymptotically flat background and that the shadow observables can be used as an efficient tool to test the effects of nonlinear electrodynamics in strong gravity. Full article

Background/Objectives: Endodontic sealers can interact with periapical tissues through extrusion, yet the molecular mechanisms underlying their biological effects remain poorly defined. This study investigated how commonly used sealers influence mitogen-activated protein kinase (MAPK) signaling, cell viability, and osteogenic-associated responses in MC3T3-E1 pre-osteoblasts. Methods: Four commercial sealers, Calcium-silicate-based Bioceramic Sealer (EndoSequence^® BC Sealer, BC), Zinc oxide eugenol sealer (Kerr Pulp Canal Sealer, ZOE), Sealapex™, and AH26^®, were applied as standardized pellets, allowed to set, and cultured with MC3T3-E1 cells. Calcium deposition was assessed by Alizarin Red S (ARS) staining, and MAPK activation was evaluated by Western blotting. Due to excessive solubility (Sealapex™) or poor cell survival (AH26^®), mechanistic analyses were performed only for BC and ZOE. Osteogenic-associated gene expression was measured by qRT-PCR, and the functional role of MAPK signaling was assessed using ERK, JNK, and p38 inhibitors. Results: BC and Sealapex™ produced robust ARS staining, while ZOE and AH26^® produced minimal mineral-associated staining. Both BC and ZOE activated ERK, JNK, and p38, with ZOE inducing higher phosphorylation. However, BC maintained greater cell viability and increased Runx2 and Osx expression, whereas ZOE impaired early cell attachment and viability. MAPK inhibition in BC-treated cultures reduced osteogenic-associated gene expression and ARS staining, indicating MAPK involvement in BC-mediated responses. Conclusions: BC and ZOE elicit distinct MAPK activation patterns and cellular responses. Under the conditions tested, BC promoted a more favorable osteogenic-associated response, whereas ZOE compromised early cell viability. These mechanistic insights may help explain clinical differences in periapical tissue responses to sealer extrusion. Full article

Background/Objectives: Well-child care plays a critical role in promoting child health and monitoring growth and development within Primary Health Care (PHC), in line with international frameworks such as the WHO Global Strategy and the UN Sustainable Development Goals (SDGs). However, the absence of standardized quality indicators limits comparability across studies and hinders continuous improvement worldwide. This study aimed to map and analyze the indicators used to assess the quality of well-child care in global PHC settings. Methods: A scoping review was conducted following PRISMA-ScR and Joanna Briggs Institute methodological guidance, with a pre-registered protocol. Comprehensive searches were performed in May 2025 across fourteen databases and two gray literature sources, without language or time restrictions. Eligible studies assessed quality indicators for well-child care among children up to 5 years, 11 months, and 29 days. Two independent reviewers performed study selection and data extraction. Results: From 6052 records, 62 studies met inclusion criteria. Out of them, most (68%) used composite indicators, primarily from pre-existing tools (67%). While structural and clinical indicators—such as immunization and service accessibility—were predominant, there was a critical absence of relational indicators focusing on patient–provider interaction. This lack of standardization and neglect of the relational dimension significantly hinders international comparability and the assessment of family-centered care quality. Conclusions: Developing and validating a core set of standardized, comprehensive, and context-sensitive indicators integrating structural, clinical, and relational dimensions is essential. These should be linked to information systems to enable robust national and international comparison, strengthen evidence-based management, and drive continuous quality improvement to achieve the 2030 Agenda goals. These findings provide a foundation for policymakers to develop standardized monitoring tools that prioritize neglected relational aspects of care. Full article

Rett syndrome (RTT) is a neurodevelopmental disorder characterized by motor deficits, partly attributed to cerebellar dysfunction. RTT is primarily caused by mutations in the gene encoding the methyl-CpG-binding protein 2 (MECP2), which has been implicated in cholesterol homeostasis by mechanisms that remain poorly understood. Given that brain cholesterol is primarily synthesized de novo and that disrupted cholesterol homeostasis is linked to various neurological disorders, we aimed to investigate cholesterol regulation in the cerebellum of Mecp2-null mice, a well-established RTT model. We measured total cholesterol levels in cerebellar tissue and cerebellar synaptosomes and assessed the expression of genes involved in cholesterol biosynthesis and intracellular transport. Our results show significantly elevated total cholesterol in both cerebellar tissue and synaptosomes. Furthermore, we identified a marked reduction in CYP46A1 expression, which is essential for the elimination of encephalon sterols. In contrast, key cholesterol biosynthetic regulators (Srebp2, Hmgcs1, Sqle) showed no significant changes in expression, suggesting an impaired cerebellar cholesterol turnover—driven by defective clearance—rather than enhanced synthesis may underlie the metabolic imbalance observed in the cerebellum of the RTT mouse model. Altogether, these findings provide a mechanistic insight into how MeCP2 deficiency disrupts cerebellar cholesterol homeostasis and highlight cholesterol clearance pathways as potential contributors to RTT pathology and a factor to consider for further RTT therapeutic approaches. Full article

Rationale: Radium-223 dichloride (²²³RaCl₂) is an FDA-approved alpha-emitting radiopharmaceutical that targets bone metastases in metastatic castration-resistant prostate cancer (mCRPC). This study investigates the therapeutic and immunological effects of combining ²²³RaCl₂ with immune checkpoint inhibitors (ICIs) in a clinically relevant, immunocompetent murine model of prostate cancer bone metastasis. Methods: Luciferase-expressing MyC-CaP prostate cancer cells were implanted intratibially into FVB mice to establish bone metastases. Mice were treated with escalating doses of ²²³RaCl₂ (0.04–0.27 µCi) alone or a single dose combined with anti-CTLA-4 and anti-PD-L1 ICIs. Tumor growth was monitored using bioluminescence imaging. Micro-CT, alpha camera imaging, histology, and qPCR were used to assess bone remodeling, radiopharmaceutical distribution, immune infiltration, and gene expression. Ex vivo biodistribution and blood analyses quantified tissue uptake and toxicity. Results: Escalating doses of ²²³RaCl₂ did not significantly inhibit tumor growth or improve survival. Biodistribution and imaging showed preferential localization of ²²³RaCl₂ to tumor-adjacent bone, with minimal signal in isolated tumor tissue. Immunohistochemistry revealed increased CD4⁺ and CD8α⁺ T-cell infiltration in regions of high γH2AX expression, indicating localized immune modulation. However, combination therapy with ICIs did not enhance tumor control or immune infiltration beyond monotherapy. qPCR demonstrated significant upregulation of Mhc1 only in the combination group, suggesting localized immune activation. Toxicity profiles remained acceptable. Conclusions: ²²³RaCl₂ localizes primarily to bone surfaces, limiting direct cytotoxic and immunomodulatory effects within the tumor microenvironment. While combination with ICIs did not improve efficacy, these findings provide a platform for studying spatial dose distribution and support future development of tumor-targeted alpha therapies to potentiate immunotherapy in mCRPC. Full article

We investigate the dynamical stability of circular orbits around a Kerr black hole embedded in a Dehnen-type dark matter halo. The effective spacetime metric of the combined system is constructed using the Newman–Janis algorithm, and the effective potential for test-particle motion in the equatorial plane is derived. The stability of circular orbits is analyzed through the Hessian matrix of the effective potential, while the stability strength and restoring-force distribution are employed to quantify the orbital response to small perturbations. Our results show that the presence of the dark matter halo significantly alters the spatial structure of stable circular orbits, leading to non-continuous stable regions whose location and extent depend sensitively on the halo’s characteristic density, scale radius, and the black hole spin. The innermost stable circular orbit (ISCO) is shifted relative to the vacuum Kerr case, with its position determined by the combined effects of the spin and halo parameters. Two-dimensional heatmaps, parameter scans, and three-dimensional visualizations systematically illustrate how the black hole spin and dark matter halo properties influence the ISCO and the distribution of stable orbits. Finally, we analyze the influence of the dark matter halo on the structure of the black hole event horizon. These results provide a detailed theoretical investigation of orbital dynamics around rotating black holes in dark-matter-rich environments. Full article

This study presents an analytical investigation into the free vibration behavior of perforated nanobeams resting on a Kerr-type elastic foundation within the framework of Eringen’s nonlocal elasticity theory. Specifically, Eringen’s nonlocal elasticity theory is employed to inherently capture small-scale effects, while the three-parameter Kerr model is utilized to provide a mathematically consistent representation of shear continuity and realistic surface interactions. In this context, the governing equations of motion for a perforated Euler–Bernoulli nanobeam are derived using Hamilton’s principle, incorporating both the nonlocal parameter and perforation geometric factors, namely, the filling ratio and the number of holes. The resulting equations are solved analytically via the Navier method for simply supported boundary conditions. The results indicate that the Kerr foundation model exhibits an intermediate behavior between the Winkler and Pasternak models, owing to the stiffness-reducing effect of its upper spring layer connected in series. A key finding is the “masking effect,” where high foundation stiffness significantly suppresses the frequency reduction caused by nonlocal small-scale effects. Furthermore, it is observed that in the absence of foundation support, the vibration behavior is governed by the competition between mass reduction and stiffness loss depending on the number of holes; however, foundation dominance stabilizes the system regardless of perforation geometry. Full article

The increasing severity of climate change poses profound challenges to global food security, particularly affecting vulnerable populations such as migrants and refugees. This scoping review examines the nexus between climate change, food security, and migration, focusing on the impacts and responses within affected communities. Guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR), this review synthesized literature across multiple databases, including Ovid MEDLINE, Embase, Global Health, Public Health, Web of Science, and PsycINFO. The search yielded 908 records, with nine articles meeting the inclusion criteria. Across studies, climate-related stressors such as rainfall variability, flooding, and drought were consistently linked to livelihood disruption and food insecurity, often shaping migration and displacement decisions. However, food security outcomes were defined and measured inconsistently, ranging from crop yields and food availability to coping strategies and self-reported hunger, limiting comparability across studies. Evidence on food security initiatives was largely descriptive, with few studies assessing intervention effectiveness or post-displacement food security outcomes. Overall, the mapped literature emphasizes food insecurity as a key mediating pathway between climate change and mobility, but reveals important gaps related to standardized outcome measures, evaluation of food security initiatives, and the food security experiences of displaced populations at destination. Full article

Modified discrete transfer matrix and transmission line models were applied to nonlinear refractive index fiber Bragg gratings (FBG). The methods were validated against analytical solutions for Kerr-type uniform FBG, evaluating accuracy, convergence, and computational time. Spectral reflectivity, bistability, index distribution, and group delay were computed for various FBG types, with results discussed for each grating, particularly regarding reflectivity and bistability. Full article

The paper retrieves quiescent dispersive solitons in dispersion-flattened optical fibers having nonlinear chromatic dispersion and the Kerr law of self-phase modulation. The platform model is the Schrödinger–Hirota equation. The enhanced direct algebraic method has made this retrieval possible. The intermediary functions are Jacobi’s elliptic function and Weierstrass’ elliptic function. The final results appear with parameter constraints for the existence of such solitons. Full article