The conversion of solar radiation into thermal energy has gained increasing attention due to the growing demand for renewable sources of heat and electricity. Nanofluids, owing to their enhanced heat transfer capabilities, play a significant role in improving the efficiency of solar thermal systems. In this study, the flow of silicone oil containing diamond and silicon dioxide nanoparticles over a curved extended permeable sheet is investigated in the presence of Darcy-Forchheimer porous medium, thermal radiation, and Lorentz force. The non-Newtonian behavior of the working fluid is modeled using the Jeffrey fluid model. The governing flow equations are transformed into ordinary differential equations (ODEs) and solved numerically using the MATLAB bvp4c solver. Furthermore, an intelligent computational approach based on the Levenberg-Marquardt algorithm combined with a multilayer perceptron (MLP) feed-forward backpropagation artificial neural network is employed. The effects of key parameters, including the Deborah number, injection/suction parameter, permeability parameter, Forchheimer number, Hartmann number, curvature parameter, Prandtl number, Eckert number, and heat generation/absorption parameter, are analyzed in terms of pressure, velocity, temperature, and heat transfer rate. The results indicate that porous resistance and magnetic effects significantly influence boundary layer formation and heat extraction efficiency, showing that optimally adjusted hybrid nanofluids can greatly enhance thermal transfer in porous solar collectors and curved absorber surfaces, thus providing valuable insights for the design of advanced solar thermal systems.
The aim of this theoretical study is to propose a surface plasmon resonance (SPR) sensor to detect the glucose levels in urine samples for improved diabetes management. The Kretschmann configuration is being modified by adding gadolinium fluoride (GdF₃) acting as a dielectric and MoS₂ (molybdenum disulfide) as a two-dimensional (2D) material layer between the plasmonic silver metal layer and the sensing medium, enabling label-free quantitative glucose detection. The performance of the proposed sensor is reliant on the layer thicknesses. To achieve the minimum reflectance (Rmin) and high sensitivity required for non-invasive diagnostics, the thickness of the layers has been optimized. The transfer matrix method (TMM) has been utilized for reflectance computation of the proposed multilayer SPR structure. At a fixed wavelength of 633 nm, the sensor performance is evaluated employing the angular interrogation technique by observing the SPR resonance angle. The key performance parameters, such as sensitivity (S), figure of merit (FoM), detection accuracy (DA), and full width at half maximum (FWHM), have been computed using MATLAB-simulated SPR curves. For a 10 g/dL glucose concentration, maximum sensitivity and FoM values of 216.66 deg/RIU and 32.71 RIU⁻1 are attained. At a wider refractive index (RI) range of 1.33 to 1.40, corresponding to physiologically relevant conditions for diabetes monitoring, the performance has been evaluated for the proposed sensor chip configuration. Within this RI range, the highest sensitivity value obtained is 300 deg/RIU with a FoM of 53.0973 RIU⁻1. These results demonstrate that the proposed multilayer structure provides a highly sensitive and reliable platform for glucose detection in diabetes, supporting the advancement of non-invasive diagnostic technologies aligned with Sustainable Development Goal 3 (Good Health and Well-Being).
In this study, antimony (Sb)-doped zinc sulfide (ZnS) thin films were synthesized via the nebulizer spray pyrolysis technique on glass substrates to explore their potential for ultraviolet (UV) photodetection. The doping concentration of antimony was systematically varied at 0, 1, 2 and 3 wt% to investigate its influence on the structural, optical and photoresponse properties. X-ray diffraction (XRD) confirms that ZnS is in hexagonal wurtzite structure, while field emission scanning electron microscopy (FESEM) revealed uniform surface morphology with grain size modulation due to Sb incorporation. UV-Visible spectroscopy indicates a tunable bandgap with Sb content. Photoluminescence (PL) analysis further evidenced the creation of defect states with optimal emission behaviour observed at 2 wt% Sb. Current-voltage (I-V) characteristics under 365 nm UV illumination demonstrated a significant enhancement in photocurrent and responsivity at the 2 wt% doping level, highlighting its suitability for efficient photodetector applications. The findings indicate that Sb-doping can be used to fine-tune the optoelectronic properties of ZnS thin films, with 2 wt% Sb identified as the most effective concentration for achieving high UV photodetector performance.
It is believed today that the planets in our Solar System evolve chaotically due to secular chaos. Their rotational dynamics are therefore subject to perturbations which lead over a long period of time to instability and chaos. This problem has been studied extensively over the last decades with the aid of computer simulations which have shown that the Solar System is chaotically unstable on a timescale akin to its age. Still, no analytical theory has acceptably and satisfactory explained the origin of chaos so far. In the present study, motivated by the relevance of nonstandard (exponential and power-law) Hamiltonians in dissipative and nonconservative dynamical systems, the nonstandard Hamiltonian approach to the spin-orbit coupling has been studied by introducing two nonstandard discrete maps. These maps are dominated by the eccentricity, the asphericity parameter, and the parameters of the nonstandard Hamiltonians. It was found that chaotic behavior is a ubiquitous feature in nonstandard Hamiltonian systems, and highly irregular fractals structures arise. We considered the case of Neptune and Mercury, where we demonstrated that nonstandard Hamiltonian approach to the spin-orbit coupling is richer in patterns than the conventional approach. Several features of chaotic behavior of Neptune and Mercury have been presented based on the analyses of the Poincare sections, the Lyapunov exponents, and the bifurcation diagrams which are reflections of the character of the trajectories in the underlying phase space. In the exponential discrete map, it was observed that both planets are non-chaotic, whereas in the power-law discrete map, Mercury may be stable in a chaotic solar system at long-term, whereas Neptune may be subject to weak instabilities. Depending on the values of the control parameters, both maps display substantially stable regimes, perpetual bifurcations, infinite number of fixed points, and chaos containing plentiful attractors. These open motivating questions addressed in the present study.
Photodetectors (PDs) are key components in optoelectronics, designed to detect light and convert it into electrical signals, enabling their use in diverse applications. This study presents the development of pristine and Sbdoped Bi2S3 thin-film UV photodetectors, employing nebulizer spray pyrolysis technique for their fabrication. Antimony (Sb) doping levels in Bi2S3 thin films were varied from 1 to 3 wt%, and their effect on structural, morphological, optical and photosensing properties has been investigated. X-ray diffraction (XRD) studies indicate an orthorhombic crystal structure with a maximum crystallite size of 22 nm for 2 wt% Sb-doped Bi2S3 thin films. The FESEM image of the 2 wt % Sb-doped film shows more compact and larger grains. Doping of Bi2S3 thin film with 2 wt% Sb caused enhanced optical absorption and shrinkage of optical bandgap from 2.33 eV (for undoped) to 2.08 eV (for 2 wt% doping). The current-voltage and current-time properties of the fabricated photodetectors were used to estimate the essential performance parameters. Time-dependent photoresponse analysis revealed response/recovery times of 0.29 s/0.89 s, respectively, for 2 wt% Sb-doped Bi2S3 thin film photodetector under 5 V bias. Optimally doped Bi2S3:Sb (2 wt%) photodetector showed photoresponsivity (R) of 0.109 AW-1, detectivity (D*) of 9.42 & times; 109 Jones and external quantum efficiency (EQE) of 37.1%. Sb-doped Bi2S3 (2 wt%) thin films, with superior photosensing capabilities and a cost-effective synthesis, are well suited for UV light sensing applications.
