Excited-state intramolecular proton transfer (ESIPT) is a key photophysical process closely related to the optical properties and antioxidant activity of functional molecules, yet its substituent-dependent regulation in nontraditional ESIPT systems remains unclear. In this work, density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed to investigate the ESIPT mechanisms, hydrogen-bond dynamics, electronic structure evolution, and antioxidant properties of 2-(2-hydroxyphenyl)pyrimidine (HPP) and its –NH2 and –NO2-substituted derivatives. Geometric optimizations, potential energy surface scans, and noncovalent interaction analyses reveal that the electron-donating –NH2 group strengthens the intramolecular O–H⋯N hydrogen bond and induces a barrierless ESIPT process with direct formation of the keto excited state (K*). In contrast, the electron-withdrawing –NO2 group stabilizes an excited enol-like intermediate (E*), leading to a stepwise proton transfer pathway with a small activation barrier. Frontier molecular orbital and natural bond orbital analyses demonstrate that photoexcitation triggers substituent-dependent charge redistribution, which governs proton transfer feasibility. Moreover, ionization potential and global reactivity index calculations indicate enhanced antioxidant activity in the excited state, particularly for HPP and HPP–NH2. These results establish a clear relationship between substituent effects, ESIPT pathways, and antioxidant performance, providing theoretical insight for the rational design of ESIPT-based photoactive antioxidants.
The nonlinear stability of roll waves in power-law fluid films on inclined planes is investigated using the Kármán momentum integral method and Whitham’s modulation theory. Depth-integrated governing equations and modulation equations are derived, yielding an integro-differential stability criterion dependent on mean and critical depths. Linear analysis shows that shear-thinning fluids have lower critical Reynolds numbers than Newtonian fluids: for n = 0.4, the linear stability threshold parameter α s = 11.25 compared to α s = 3 for n = 1. Nonlinear analysis reveals dual mechanisms of roll wave generation – linear instability and subcritical bifurcation. Asymptotic analysis overcomes the singularity at maximum amplitude, enabling the systematic construction of nonlinear stability diagrams. We identify a critical power-law index n cr ≈ 0.7 for α = 2.0, below which shear-thinning unexpectedly promotes stable wave formation. For strongly shear-thinning fluids (n = 0.4), a critical inclination parameter α cr ≈ 0.2 marks the onset of a regime where milder slopes favor wave stability – a nonlinear phenomenon arising from the competition between inertia and dissipation. Only roll waves with amplitudes exceeding a saturation threshold can propagate stably. These findings provide theoretical guidance for engineering control of non-Newtonian film flows.
Vector vortex beams not only exhibit unique polarization phase characteristics but also carry orbital angular momentum (OAM), making them widely applicable in fields like optical communication and optical microscopy. In addition, studying the scattered light field from random rough surfaces can provide insights for object recognition. Considering polarization effects in the reflection of light from randomly rough surfaces enabled more accurate modeling of the physical processes governing light propagation. This study presents a simulation model for the light field reflected by a vector vortex beam after interaction with a randomly rough surface. A comparative analysis of the peak distribution patterns of the reflected light field was conducted across different polarization states, topological charges, surface roughness, and materials. The simulation results demonstrate that azimuthally polarized vortex beam (APVB) are the least susceptible to perturbations induced by rough surfaces; remarkably, the beam spot symmetry remains at 91.98 % even at a substantial roughness of σ = 20 μm. Specifically, APVB characterized by a topological charge of l = 0 and a polarization order of m = 1 exhibit superior spatial stability. Conversely, when the condition m = l is met, the beams undergo a singularity-weakening effect, which precipitates a pronounced spatial broadening of the intensity profile. An experimental optical system based on the Stokes parameter method was designed to measure the polarization degree of APVB light with l = 0 and m = 1 reflected from the surfaces of materials such as silica, aluminum and steel. The results demonstrate that a surface roughness of σ = 1.5 μm, the degree of polarization (DOP) of the reflected light field from the SiO2 surface precipitously drops to 0.15. The DOP of the beam reflected from the Al surface maintains a relative stability of approximately 0.48, even at an equivalent or higher roughness (σ = 2.1 μm). Ultimately, the theoretical framework and empirical data presented in this study provide a robust foundation for advancing optical target detection and material recognition technologies.
In Satcom-on-the-Move (SOTM) terminals, monopulse tracking maintains antenna alignment during platform motion. Compact implementations may expose only exported sum and difference channels, while jamming and interference can corrupt {Σ, Δx, Δy}, distort monopulse ratios, and pull the tracking loop away from the desired satellite. This paper presents a receiver-side physics-consistent monitor operating directly on these channels without blind direction finding, jammer parameter estimation, or full element-space data. A calibrated two-dimensional ratio manifold describes the expected desired-source response. Its geometry supports a static tangent-rejected detector for off-manifold corruption and a dynamic innovation-based detector for persistent jammer-induced pull. Their outputs are fused through a dependence-aware tempered sequential Bayesian recursion to produce the jammer posterior. The framework includes the signal and beam-space model, calibration procedure, and performance benchmarks. It is demonstrated on a digital monopulse front-end under noise-like, coherent, and mixed jamming, with two mismatch conditions. Results show strong fused detection across the tested modes, with the hardest cases occurring under weak jamming. In a representative mixed-jammer stress case, effective detection is maintained at separations down to 1° and a jammer-to-signal ratio (JSR) of 0 dB, while performance is near saturation outside that stress region.
This paper provides a comprehensive study of the behavior of charged and neutral particles around an AdS-Schwarzschild black hole with quintessence. The study incorporates a general time-conformal factor to investigate the effects of time on particle dynamics. Using the Lagrangian formalism of the black hole, we derive Noether symmetry equations, resulting in a set of 19 partial differential equations (PDEs). Solutions to these PDEs reveal the Noether symmetries, approximate Noether symmetries, and conservation laws associated with the black hole. We further analyze how parameters such as the magnetic field and angular momentum affect the particle dynamics, focusing on their effective potential, effective force, and escape velocity. Additionally, the Lyapunov exponent is employed to assess the stability of particle orbits within the described time-conformal spacetime.
We generalize the quasi-isotropic solution of the Einstein equations near a cosmological initial singularity to models with a varying speed of light and/or a varying gravitational ‘constant’. We construct a formal asymptotic series expansion in a synchronous reference system, taking into account the additional degrees of freedom introduced by the two varying ‘constants’. By applying the Landau–Lifshitz quasi-isotropic method, we go beyond the standard results of previous studies that based on the Friedmann–Lemaître–Robertson–Walker (FLRW) model, providing a more general asymptotic analysis of varying speed of light cosmologies. We show that the resulting solutions do not contain the required number of arbitrary functions to qualify as general solutions of these theories.
This article highlights neutron population kinetics by an FF-order dynamical system. The model is investigated for the solution’s existence, uniqueness of solution, and stability results as well as for the numerical simulations that were executed in MATLAB. AI-NN tools are employed to develop a predictive mechanism based on neutron population, enhancing predictive potential. Model accuracy was studied with the help of MSE, which shows high predictive performance. A performance histogram is obtained for the simulation results with very small variations between outputs and target values. The error is approximated by 10−4, with R ≈ 1, showing strong accuracy of the integrated technique of modeling with neural networking for the population dynamics analysis of neutrons.
In this manuscript, we derive soliton solutions for the (2 + 1)-dimensional nonlinear dissipative Zabolotskaya-Khokhlov equation. This equation addresses nonlinear effects in stratified media and controls the diffraction of sound beam propagation. The dynamical wave solutions are generated by using the bilinear neural network method. These solutions are composed by the specific activation functions of single-layer "3-3-1" model, to obtain the breather wave and lump wave soliton solutions. Meanwhile, a "3-4-1" a model is used to derive the lump wave interaction with the double exponential functions. Moreover, the double-layer model activation function "3-3-4-1" is considered to get the rough wave solitons, while a "3-2-2-1" model is applied to construct the periodic wave. The symbolic computational software Maple is used to verify these solutions and to draw plots for the physical interpretation. The graphical visualization of these solutions is shows in the form of three-dimensional, line and density plots. These results may shed some light in our understanding of the nonlinear dissipative Zabolotskaya-Khokhlov equation.
This study explores the significant role of soliton solutions in being stable and localized wave phenomena through diverse fields, including optical communications, fluid dynamics, and plasma physics. The investigation focuses on the fifth-order nonlinear Wazwaz equation, selected for its integrable structure and its effectiveness in modeling complex nonlinear physical processes. The modified Sardar sub-equation method is employed to obtain exact solitary wave solutions. This technique yields a wide range of analytical forms that can be written via trigonometric and hyperbolic functions. The results are shown through broad graphical analyses such as 3D, 2D, and density plots that illustrate different wave structures, including dark, lattice, periodic singular, and single solitons. In addition, a bifurcation exploration is functioned to investigate the system’s dynamic properties. Overall, this study enhances our theoretical understanding of soliton dynamics in the fifth-order Wazwaz equation and highlights its wide range of potential applications in both scientific and engineering fields.
This study explores the differential geometry of a charged particle’s motion on a unit sphere S2 within specific force fields, incorporating fractional calculus. It formulates the fractional derivative for spherical vector fields, characterizes magnetic flows via Lorentz fractional forces, and obtains the parallel transport law and constant-velocity motion equations for spherical fractional curves through fractional differentiation.
The core of multi-spectral radiation thermometry lies in determining the object’s emissivity. However, existing methods generally suffer from issues such as low accuracy and poor applicability. This paper establishes a relevant mathematical model and constraint conditions based on Planck’s radiation law and multi-objective constraint optimization theory. By integrating the particle swarm optimization (PSO) and JAYA algorithms, the proposed approach addresses the tendency of PSO to get trapped in local optima and the slower convergence speed of the JAYA algorithm. Simulation experiments conducted under four different wavelength and emissivity models at a true temperature of 2,000 K demonstrate that the PSO-JAYA method achieves a retrieval error of only 0.8 % and significantly improves retrieval speed. The method exhibits notable advantages in both retrieval accuracy and efficiency, confirming its reliability for practical applications.
Motivated by the need for controllable fast-light platforms in compact photonic systems, this work investigates surface plasmon polariton (SPP)-assisted superluminal group propagation in a four-level cesium atomic medium driven by Laguerre-Gaussian control fields. The aim is to examine how the beam waist and intensity of the structured control fields, together with plasmonic field confinement, modify absorption, dispersion, group index, and group velocity. Using a density-matrix formulation, the probe-field coherence is obtained, the optical susceptibility is calculated, and the group velocity is evaluated from the dispersion slope while the SPP contribution is included through the effective dielectric response. The results show that increasing the Laguerre-Gaussian beam waist broadens the spatial region of anomalous dispersion and negative group index, while SPP confinement strengthens the local atom-field interaction and enhances susceptibility modulation. The study demonstrates a tunable route for controlling localized superluminal group propagation without implying superluminal information transfer, with potential applications in optical switching, photonic signal processing, plasmonic sensing, and quantum optical devices.
Based on generalized bio-thermoelasticity with mass diffusion model, this paper examines the bio-thermal-diffusion interactions problem in living tissues. A decaying exponentially pulsed heat boundary flux is applied to the surface. The basic equations of generalized bio-thermoelastic-diffusions are considered without energy dissipation and are then expressed in the Laplace domain. Using the eigenvalue approach, the analytical solution in the transformed domain was derived. The results are presented numerically and are shown graphically for, temperature, concentration, stress, displacement, and chemical potential. The blood perfusion rates and the impact of various thermoelastic models on physical quantities are discussed and analyzed using visual graphs. The biomedical responses impacted by the bio-thermo-diffusion model on the wave propagation in biological tissues provide insight into the study of the model.
The present work examines the asymptotic behavior and stability of global solutions to the three-dimensional incompressible Navier-Stokes equations, framed within the context of nonhomogeneous Lei-Lin-Gevrey spaces. Building on prior findings regarding global existence and decay, we demonstrate that the norm of the global solution diminishes as time progresses towards infinity. Additionally, we formulate a stability theorem, substantiating that global solutions maintain proximity to one another in the presence of sufficiently minor perturbations of the initial conditions. These findings broaden the scope of earlier research concerning Lei-Lin and Fourier-Lei-Lin spaces to encompass the Gevrey framework.
A plasma source with an inductive coupling can effectively modify and etch metals and semiconductors used in photosensitization and optoelectronics materials. This paper focuses on modelling two-dimensional argon-chlorine plasma in an inductively coupled plasma (ICP) reactor using COMSOL Multiphysics. The molecular dynamics, electromagnetic field, induction currents, heat transfer, and fluid dynamics distributions are investigated for efficient plasma processing. Simulated results indicate that higher pressure confines the discharge, reducing the density of electrons at the substrate location, which would tend to reduce the ion and radical fluxes available for etching. With rising source power, ion flux increased, but the mean ion energy doesn’t change much. Plasma electronegativity decreases with increasing RF power, and the discharge switches between capacitive and inductive mode. On the other hand, plasma electronegativity increases with increasing chlorine concentrations, and it becomes more significant up to 50 % of chlorine concentrations. However, molecule species lose energy, resulting in a rapidly declining electron density with increasing chlorine content. The simulation study enables the accurate extraction of operating conditions of ICP reactors using an Ar/Cl2 mixture that significantly enhances uniform etching without damaging the material.
The nonlinear dynamics and solitonic structures of coupled modified complex Ginzburg-Landau equations with Kerr nonlinearity and Hamiltonian perturbations are examined in this work. Bifurcation analysis is used to find parameter regimes linked to qualitative changes in system behavior once the coupled PDEs have been appropriately transformed into an ordinary differential equation. Poincare maps, return maps, power spectra, bifurcation diagrams, and Lyapunov exponents with fractal dimensions (box-counting method, correlation sum, and the Kaplan-Yorke dimension) are then used to analyze chaotic dynamics. Furthermore, the generalized exponential rational function method is used to derive accurate traveling-wave solutions of the exponential, trigonometric, and hyperbolic types. The results demonstrate the complexity and uniqueness of the suggested model by highlighting intricate dynamical aspects and exposing multiple families of soliton solutions.
The global demand for clean and sustainable hydrogen fuels has driven the search for efficient photocathode materials capable of converting seawater directly into hydrogen without sacrificial agents. In this study, we report the fabrication of a Ni(III) oxide/poly(2-chlorobenzeneamine) (Ni2O3/P2CBA) nanocomposite through a simple one-pot dark oxidation route using NiCl2 as the oxidizing agent. The as-synthesized nanocomposite exhibits high crystallinity with an average crystallite size of similar to 12 nm, and a coral-like porous morphology (similar to 100 nm pore size), as confirmed by XRD and SEM analyses. Optical studies reveal a direct bandgap of 1.9 eV, enabling broad absorption extending from the visible to the infrared region. The Ni2O3/P2CBA photocathode was evaluated for hydrogen evolution from both natural Red Sea seawater and artificial seawater under simulated solar illumination. The measured photocurrent densities (J(ph)) reached -0.026 mA cm(-2) for natural seawater and -0.024 mA cm(-2) for artificial seawater, corresponding to hydrogen generation rates of 0.5 and 0.4 mu mol h(-1) cm(-2), respectively. These findings demonstrate that the Ni2O3/P2CBA nanocomposite offers an efficient, stable, and scalable platform for sacrificial-agent-free hydrogen generation from seawater. The simple synthesis, strong optical response, and environmental compatibility highlight its promise for future large-scale renewable hydrogen production systems.
Detecting humidity is considered as a critical issue for electronic devices, healthcare, industrial operations, and environmental monitoring, necessitating the development of high-performance sensors. Reduced graphene oxide (rGO) was functionalized with alkali metals (Li, Na, K), alkaline-earth metals (Mg and Ca), the transition metal Cu, and copper oxide (Cu2O) to improve its interaction with humidity (H2O). The density functional theory (DFT) at the B3LYP/LANL2DZ level was used to optimize structures and investigate electronic properties, such as HOMO-LUMO energy gaps (Delta E), density of states (DOS), molecular electrostatic potential (MESP), and global reactivity descriptors. Among the studied systems, it was found that, rGO/5K, rGO/2Mg, rGO/2Ca and rGO/2Cu exhibited decreased bandgaps, increased reactivity, and orbital redistribution. Interaction with H2O demonstrated hydrogen bonding via QTAIM analysis, which is an important interaction mechanism. Adsorption energy (E-a) calculations identified rGO/2Ca and rGO/2Mg as the optimal candidates with high H2O affinity and significant Delta E modulation. The findings point to the possible application of metal-decorated rGO as humidity sensor, facilitating its applications in both environmental monitoring and smart sensing technology. These findings offer a critical contribution to the field by demonstrating how specific alkali and transition metal decorations, particularly Ca and Mg, uniquely lower resistance to charge transfer, thereby defining a new frontier for highly responsive and stable graphene-based humidity sensors.
Since multi-scale processes and anomalous diffusion phenomena are important in various scientific fields, including biology, materials science, and physics, this work analytically examines the stochastic reaction-diffusion model. The coupled diffusion equation is solved using both analytical methods and numerical simulations. These approaches reveal emerging phenomena and provide insights into the dynamics of complex diffusing entities. The results help improve understanding in domains such as plasma physics and optical fibers by clarifying the range of solutions to this equation. A modified exponential rational function technique is used to obtain exact analytical results. This technique produces a variety of traveling wave solutions, including trigonometric, exponential, rational, and hyperbolic forms. The approach also enables the exploration of several solutions from significant physical perspectives, including soliton solution, periodic solitons, kink solitons, singular and rational solution as well as their noise term effects on Brownian motion, based on the Ito sense. The effects of the noise term on solitons are illustrated using two-dimensional (2D) and three-dimensional (3D) graphics. The suggested method is simple and effective for solving various nonlinear equations in mathematical physics. The properties of some solutions under multiplicative temporal noise are displayed using various charts.
The self-assembly of 1,3,6,8-tetrabromopyrene (Br4Py) on Au(111) leads to two competing monolayer structures, M1 and M2, with near-identical formation energies. First-principles calculations reveal that this structural duality originates from distinct hierarchical pathways: three stable molecular chain intermediates (C1-C3), identified via energy minimization, first form through a balance of directional Br & ctdot;H hydrogen bonds and repulsive Br & ctdot;Br interactions, with the former acting as the primary structural driver. These chains then laterally organize into the monolayers, where M1 arises from complementary C1/C2 chain packing and M2 from homologous C3 chain assembly. The simulated structural parameters (e.g., lattice constants b/c approximate to 21.70 & Aring;, Br & ctdot;H distances approximate to 3.23 & Aring;) are in good agreement with scanning tunneling microscopy data, showing deviations below 6 %. Electron density analysis quantitatively corroborates the competitive interplay, showing charge accumulation at Br & ctdot;H bonding sites and depletion in Br & ctdot;Br repulsive zones. Substrate-mediated strain from Au(111) induces lattice distortions up to 5.8 %, highlighting the role of surface-molecule coupling. By integrating computational and experimental insights, this work establishes a mechanistic framework for understanding and designing halogen-mediated, surface-confined supramolecular assemblies with potential in molecular electronics. This framework highlights the exquisite structural control achievable through halogen bonding and substrate effects, and lays the groundwork for future explorations on alternative surfaces, molecular derivatives, and device integration.
