This study investigates the distribution, fractionation, sources, and ecological risks of potentially toxic elements (PTEs) in coastal sediments from Yanbu, an industrial region along the Red Sea. Surface sediments from 10 sites were analyzed for Fe, Mn, Zn, Cu, Pb, Ni, Co, and Cd using sequential extraction, pollution indices, multivariate statistics, and positive matrix factorization (PMF). Mean total concentrations (mg/kg) followed the order Fe (5313.60) > Mn (268.60) > Zn (101.93) > Cu (31.87) > Ni (22.38) > Co (6.32) > Pb (5.36) > Cd (0.28), suggesting substantial lithogenic contributions. Although residual fractions exceeded 50% for all elements, Cd, Cu, Mn, and Zn exhibited appreciable labile fractions, indicating potential mobility and bioavailability. Mean risk assessment code (RAC) values indicated medium risk for Cu (24.24%), Mn (21.51%), Cd (20.86%), Zn (19.69%), Pb (18.09%), Co (17.31%), and Ni (16.70%), whereas Fe presented low risk (8.78%). The conventional ecological risk index (RI = 37.9) indicated low regional risk, contrasting with the speciation-based index (AIT = 0.57), which suggested elevated risk associated with metal bioavailability. Spatial assessment identified localized pollution hotspots at stations 5–6 (NPI > 7). PMF attributed 68% of the metal load to direct anthropogenic sources, increasing to 82% when mixed sources were included. These findings highlight the importance of integrating total concentrations, chemical fractionation, ecological indices, and source apportionment to distinguish regional contamination levels from localized bioavailability concerns. This study provides a baseline for environmental monitoring and sustainable management of industrially influenced coastal sediments along the Red Sea.
Abstract To meet the rising global energy demand, offshore wind turbines (OWTs) are increasingly deployed in deeper marine environments where wind conditions are more favorable. This transition exposes OWTs to intensified environmental loads—such as wind, wave, and rotor-induced dynamic forces—creating unique challenges to foundation designers. To address these challenges and reduce the escalating costs associated with large-diameter monopiles (MP), this study introduces a novel hybrid foundation (HF) system. The HF integrates a shallow circular plate at the seabed with a centrally embedded monopile of reduced diameter and length, offering an alternative to conventional monopile foundations. Through a combined approach of centrifuge modeling and three-dimensional finite-element analysis, this research investigates the influence of HF pile length ( L p ) to plate diameter ( W ) and varying clay soil shear strength ( s u ) and stiffness ( E 50 ) properties on the HF lateral ultimate capacity ( H u ) under eccentric loading conditions. The centrifuge tests simulate overconsolidated clay beds under lateral and overturning loads, and results demonstrate that increasing the L p / W ratio enhances the normalized H u while higher E 50 / s u limits this improvement. Unlike conventional monopiles, the HF system shows reduced sensitivity to MP diameter. Under service load conditions, the HF reduced pile bending moments by 30%–45% and tower tip displacements by up to 200%, confirming its potential to support next-generation OWTs in cohesive soils with improved structural efficiency and cost-effectiveness.
Resistant bacteria and their biofilms reduce the efficacy of conventional antibiotic therapies. To address this, a nanoplatform consisting of silver nanoparticles coated with chitosan and dual-loaded with thymol and luteolin (AgNPs@CS-TH-LU) was prepared and evaluated through in vitro and in vivo assays. The nanocomposite showed a well-dispersed spherical morphology with an average particle size of 69 nm and a zeta potential of +38 mV in deionized water. Well diffusion assays showed inhibition zones of ∼28 mm against S. aureus, E. coli, S. agalactiae, and P. aeruginosa, with MIC values as low as ∼0.30 μg mL−1 (total nanocomposite concentration) and ∼ 98% biofilm inhibition. The release profile was prolonged and pH-responsive over 24 h. Hemolysis was low ∼2.33% at 400 μg mL−1 under the tested conditions. In mice, AgNPs@CS-TH-LU showed reduced toxicity compared with bare AgNPs, with liver enzymes and organ weights close to control values, and in vivo wound-healing trials exhibited complete wound closure in 11 days with enhanced collagen deposition. These findings suggest AgNPs@CS-TH-LU is a promising nanocomposite with enhanced antibacterial activity, reduced toxicity relative to bare AgNPs, and accelerated wound healing in mice under the tested conditions.
Global IP traffic growth is pushing conventional C-band erbium-doped fiber amplifiers (EDFAs) toward their practical capacity limit, making ultra-wideband amplification across the S+C+L spectrum a pressing technical need. This paper proposes two hybrid optical amplifier (HOA) architectures, TDFA–EDFA and TDFA–Raman, for continuous amplification across 1460–1625 nm (165 nm, 34 WDM channels at 5 nm spacing), and evaluates them numerically under dense WDM conditions for gain, noise figure (NF), optical signal-to-noise ratio (OSNR), amplified spontaneous emission (ASE) power spectra, and nonlinear transmission impairments including self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM). Whereas the TDFA amplifies the S-band and the EDFA/Raman stage amplifies the C+L bands, this work additionally decomposes the total gain into its per-stage contributions to clarify how each stage shapes the composite spectrum. The TDFA–Raman configuration reaches a peak gain of 48.8 dB with a 3 dB ripple and NF below 5 dB across the full band, while the TDFA–EDFA configuration reaches approximately 30 dB gain with a ripple within 4 dB and NF of 3.5–5.5 dB. Bidirectional TDFA pumping is shown to suppress ASE accumulation and flatten gain relative to forward-only pumping. Fiber and pump parameters used in the model are benchmarked against previously published experimental and numerical TDFA and Raman results to confirm their physical plausibility. Parametric sweeps of TDFA length (5–20 m) and Raman pump power (500–1300 mW) expose the trade-off between peak gain and spectral uniformity, and a gain-flattening filter (GFF) is introduced between the TDFA and Raman stages; its simulated transfer function is shown to reduce gain ripple substantially at the cost of quantified peak-gain and NF penalties. Nonlinear analysis shows FWM as the dominant S-band impairment at high Raman pump power, motivating a recommended pump-power cap of 900–1000 mW, while SPM and XPM remain within acceptable bounds in both architectures. A consolidated comparison against ten recently reported HOA designs confirms the competitiveness of the proposed architectures in bandwidth coverage, gain, and noise performance.
The increasing demand for compact and energy-efficient heat exchangers has accelerated the development of passive heat transfer enhancement techniques and intelligent predictive tools for improved thermal system design. In the present study, an experimental and machine learning-based investigation was conducted to evaluate the thermo-hydraulic performance of a counter-flow double-pipe heat exchanger equipped with helical wire coil (WC) inserts under turbulent flow conditions. The novelty of this work lies in the systematic assessment of fifteen insert configurations by combining three wire diameters (1.0, 1.5, and 2.0 mm) with five pitch ratios (P/Dc = 0.625, 1.25, 1.875, 2.5, and 3.125). Experiments were performed over a Reynolds number range of 5500-15000, and the experimental setup was validated against established Nusselt number and friction factor correlations. The thermo-hydraulic performance was evaluated using the heat transfer coefficient, Nusselt number, friction factor, pressure drop, and thermal performance factor. The results showed that the wire coil inserts generated strong swirl flow and secondary vortices, which enhanced fluid mixing and suppressed thermal boundary layer development, resulting in a maximum Nusselt number enhancement of 126.7% compared with the plain tube. The highest Nusselt number (180.24) was achieved using a 2 mm wire diameter with a P/Dc of 0.625. Although the friction factor increased by 156.5-410.8% due to greater flow resistance, the thermal performance factor remained above unity (1.01-1.35) for all configurations, confirming the overall thermohydraulic effectiveness of the inserts. Furthermore, Linear Regression, Ridge Regression, Random Forest, and Gradient Boosting models were developed to predict the heat transfer and flow characteristics. Among them, the Gradient Boosting model demonstrated the highest prediction accuracy, achieving R2 values of 0.9984 and 0.9971 for the Nusselt number and friction factor, respectively, highlighting the potential of machine learning for the rapid design and optimization of advanced heat exchanger systems.
