Search Results (3,889)

The solid electrolyte interphase (SEI) is a passive layer, typically a few hundred angstroms thick, that forms on the electrode surface in the first few battery cycles when the electrode is in contact with the electrolyte in lithium-metal batteries. Composed of a combination of lithium salts and organic compounds, the SEI plays a critical role in battery performance, serving as a channel for Li-ion shuttling. Its structure typically comprises an inorganic component-rich sublayer near the electrode and an outer organic component-rich sublayer. Understanding heat transport through the SEI is crucial for improving battery pack safety, particularly since the Li-ion diffusion coefficient exhibits an exponential temperature dependence. This study employs first-principles calculations to investigate phonon-mediated temperature-dependent lattice thermal conductivity across the inorganic components of the SEI, including, LiF, Li₂O, Li₂S, Li₂CO₃, and LiOH. This study is also extended to the dependence of the grain size on thermal conductivity, considering the mosaic-structured nature of the SEI. Full article

Technological advancements for the miniaturization of electronic components highlight a critical role of thin and durable stencils in advanced surface mount technology. Here, we report a transparent and fine film stencil consisting of a clear polyimide film and a functional diamond-like carbon coating layer for the fine-pitch surface mount technology process. High-quality and burr-free apertures in the thin film result from the thermally stable laser-cut process using a repetitive and low-power irradiation of nanosecond pulse laser, enhancing the printing accuracy of solder paste with fewer solder joint defects. The carbon coating layer with an electrostatic discharge composition facilitates smooth and robust surfaces and sidewalls of the apertures for the high solder paste release and high mechanical durability of the fine film stencil. The low-cost and easy fabrication of the fine film stencil accelerates the potential industrial replacement of the conventional metal stencils at a reduced thickness and further open a new opportunity for the mass production of the fine-pitch surface mount technology process. Full article

Graphene/h-BN/Si heterostructures show considerable potential for future use in infrared detection and photovoltaic technologies due to their adjustable electrical behavior and well-matched interfacial structure. The near-lattice match between graphene and hexagonal boron nitride (h-BN) enables the deposition of low-defect-density graphene on h-BN surfaces. This study presents a thorough exploration of the low-frequency electrical noise behavior of graphene/h-BN/Si heterojunctions under both forward and reverse bias conditions at room temperature. Graphene nanolayers were directly grown on h-BN films using microwave plasma-enhanced CVD. The h-BN layers were formed by reactive high-power impulse magnetron sputtering (HIPIMS). Four h-BN thicknesses were examined: 1 nm, 3 nm, 5 nm, and 15 nm. A reference graphene/Si junction (without h-BN) prepared under identical synthesis conditions was also studied for comparison. Low-frequency noise analysis enabled the identification of dominant charge transport mechanisms in the different device structures. Our results demonstrate that grain boundaries act as dominant defects contributing to increased noise intensity under high forward bias. Statistical analysis of voltage noise spectral density across multiple samples, supported by Raman spectroscopy, reveals that hydrogen-related defects significantly contribute to 1/f noise in the linear region of the junction’s current–voltage characteristics. This study provides the first in-depth insight into the impact of h-BN interlayers on low-frequency noise in graphene/Si heterojunctions. Full article

To investigate the effect of laser cleaning on the chromium plating of steel tyre moulds, a solid-state laser with an average power of 500 W was used as the cleaning light source. By varying the energy density and the number of pulses applied to the exact location, the changes in the macro- and micro-morphology of the mould surface, surface element content, and chromium plating thickness before and after laser cleaning were studied. The results show that as the laser energy density increases, the cleaning effect improves significantly. However, when the energy density exceeds $1.02\times {10}^4$ mJ/cm², cracks appear in the chrome-plated layer. By changing the number of pulses applied to a specific location, it was found that cracks also appear in the chrome-plated layer when the number of pulses exceeds three. These results provide a reference for the practical application of laser cleaning in the cleaning of chrome-plated steel tyre moulds. Full article

High-precision Sea Surface Temperature (SST) prediction is critical for understanding ocean–atmosphere interactions and climate anomaly monitoring. We propose GRU_EKAN, a novel hybrid model where Gated Recurrent Units (GRUs) capture temporal dependencies and the Enhanced Kolmogorov–Arnold Network (EKAN) models complex feature interactions between SST and multivariate ocean predictors. This study integrates GRU with EKAN, using B-spline-parameterized activation functions to model high-dimensional nonlinear relationships between multiple ocean variables (including sea water potential temperature at the sea floor, ocean mixed layer thickness defined by sigma theta, sea water salinity, current velocities, and sea surface height) and SST. L2 regularization addresses multicollinearity among predictors. Experiments were conducted at 25 South China Sea sites using 2011–2021 CMEMS data. The results show that GRU_EKAN achieves a superior mean R² of 0.85, outperforming LSTM_EKAN, GRU, and LSTM by 5%, 25%, and 23%, respectively. Its average RMSE (0.90 °C), MAE (0.76 °C), and MSE (0.80 °C²) represent reductions of 31.3%, 27.0%, and 53.2% compared to GRU. The model also exhibits exceptional stability and minimal Weighted Quality Evaluation Index (WQE) fluctuation. During the 2019–2020 temperature anomaly events, GRU_EKAN predictions aligned closest with observations and captured abrupt trend shifts earliest. This model provides a robust tool for high-precision SST forecasting in the South China Sea, supporting marine heatwave warnings. Full article

Plasma nitriding is a thermo-chemical treatment widely used to improve the tribological properties of austenitic stainless steel, due to the formation of an expanded austenite layer, which presents increased hardness. Although low-temperature plasma nitriding of austenitic stainless steels has been extensively studied in recent years, the reported results consistently show similarly high nitrogen concentrations, owing to the diffusive nature of the process. Excess nitrogen in the expanded austenite can impair the integrity of the treated surface and thus compromise the overall viability of the treatment. In such a context, the present work evaluated the use of intermittent nitrogen flow during plasma nitriding of ISO 5832-1 steel to control nitrogen concentration in the layer formed. Throughout the treatments, alternated cycles were applied between nitrogen flow periods and periods of interruption, which were repeated throughout the process. Different pulse conditions were used, in which the nitrogen flow corresponded to 10%, 15% and 50% of the cycle time. The results indicated that, in the intermittent flow condition with 50% time of nitrogen offer, the layer thickness, nitrogen concentration, and hardness values were very close to those observed in treatments carried out with continuous flow. On the other hand, in the conditions where the nitrogen flow was kept at 10% and 15% of the cycle, more significant differences were observed compared to the results obtained in continuous flow treatments. Nevertheless, those samples presented a substantial improvement in the surface hardness compared with the untreated steel. Therefore, the intermittent nitrogen flow can be used during plasma nitriding to control expanded austenite properties, enabling the design of surface properties. Full article

This work analyzes the radiation shielding effectiveness of biocompatible hydrogel pads containing carbohydrate-based polymer matrices (Alginate, Chitosan, and Cellulose) integrated with the high atomic number (Z) fillers Bismuth Oxide (Bi₂O₃) and Zinc Oxide (ZnO). The Monte Carlo-based toolkit, Geant4, was used to simulate the deposition of the dose throughout a multilayer phantom that mimics the skin (Epidermis, Dermis, Subcutaneous, and Muscle) with a pad on top irradiated with photon and electron beams from 50 keV to 1000 keV. The results indicated that Bi₂O₃ succeeded in causing greater absorption of photons at doses, particularly in deep-layer tissues, from the increase in the filler content as well as the pad thickness. The Cellulose–Bi₂O₃ composites (10 mm thick) not only showed the best deep-shielding property among all investigated combinations but also the Alginate-based pads generally performed better with regard to the surface dose attenuation. The results demonstrate the promising potential of high-Z-doped hydrogels in serving as flexible, light, and biocompatible shielding materials for superficial radiotherapy. Full article

Fast, spark-free detection of hydrogen leaks is indispensable for large-scale hydrogen deployment, yet electronic sensors remain power-intensive and prone to cross-talk. Optical schemes based on surface plasmons enable remote read-out, but single-metal devices offer either weak H2 affinity or poor plasmonic quality. Here we employ full-wave finite-difference time-domain (FDTD) simulations to map the hydrogen response of nanohole arrays (NAs) that can be mass-produced by colloidal lithography. Square lattices of 200 nm holes etched into 100 nm films of Pd, Mg, Ti, V, or Zr expose an intrinsic trade-off: Pd maintains sharp extraordinary optical transmission modes but shifts by only 28 nm upon hydriding, whereas Mg undergoes a large dielectric transition that extinguishes its resonance. Vertical pairing of a hydride-forming layer with a noble metal plasmonic cap overcomes this limitation. A Mg/Pd bilayer preserves all modes and red-shifts by 94 nm, while the predicted optimum Ag (60 nm)/Mg (40 nm) stack delivers a 163 nm shift with an 83 nm linewidth, yielding a figure of merit of 1.96—surpassing the best plasmonic hydrogen sensors reported to date. Continuous-film geometry suppresses mechanical degradation, and the design rules—noble-metal plasmon generator, buried hydride layer, and thickness tuning—are general. This study charts a scalable route to remote, sub-ppm, optical hydrogen sensors compatible with a carbon-neutral energy infrastructure. Full article

This work investigates the intricate dynamics of the Carreau hybrid nanofluid’s inclined magnetohydrodynamic (MHD) flow, exploring both active and passive control modes. The study incorporates critical factors, including Arrhenius activation energy across a stretched sheet, chemical interactions, and nonlinear thermal radiation. The formulation of the boundary conditions and governing equations is inherently influenced by symmetric considerations in the physical geometry and flow assumptions. Such symmetry-inspired modeling facilitates dimensional reduction and numerical tractability. The analysis employs realistic boundary conditions, including convective heat transfer and control of nanoparticle concentration, which are solved numerically using MATLAB’s bvp5c solver. Findings indicate that an increase in activation energy results in a steeper concentration boundary layer under active control, while it flattens in passive scenarios. An increase in the Biot number ($Bi$) and relaxation parameter ($\mathsf{\Gamma }$) enhances heat transfer and thermal response, leading to a rise in temperature distribution in both cases. Additionally, the 3D surface plot illustrates elevation variations from the surface at low inclination angles, narrowing as the angle increases. The Nusselt number demonstrates a contrasting trend, with thermal boundary layer thickness increasing with higher radiation parameters. A graphical illustration of the average values of skin friction, Nusselt number, and Sherwood number for both active and passive scenarios highlights the impact of each case. Under active control, the Brownian motion’s effect diminishes, whereas it intensifies in passive control. Passive techniques, such as zero-flux conditions, offer effective and low-maintenance solutions for systems without external regulation, while active controls, like wall heating and setting a nanoparticle concentration, maximize heat and mass transfer in shear-thinning Carreau fluids. Full article

This study explores the potential application of lignin nanoparticles and chitosan–lignin nanoparticles (CLNs) as hydrophobic barrier coatings for paperboard. The lignin nanoparticles were initially prepared using a mixed solvent of ethanol and acetone. Their characteristics were examined via scanning electron microscopy (SEM) and dynamic light scattering, which revealed particle sizes in the range of 180–400 nm. The results indicated that the coatings with pure lignin nanoparticles failed to impart hydrophobicity to the paperboard, whereas the CLN coatings significantly enhanced hydrophobicity and reduced water absorption. The water contact angle increased from 109° to over 128° after the first CLN coating, remained at 127° with the second and third coating layers, and was maintained at 119° with four layers. Multilayer coatings were applied to improve barrier performance; however, no further enhancement in hydrophobicity was observed. The CLN-coated paper exhibited a significantly improved surface smoothness, as confirmed by SEM. The results indicate that a single-layer CLN coating is effective for imparting water-barrier properties to paperboard. In contrast, the coating with pure lignin nanoparticles resulted in cracked surfaces and inconsistent coating thicknesses. Full article

This study investigates the effectiveness of an environmentally friendly coating in mitigating corrosion and preserving the mechanical properties of carbon steel, copper, and aluminium. The coated and uncoated samples were subjected to a 20-day immersion in 5% NaCl solution. Corrosion behaviour was assessed using Linear Sweep Voltammetry (LSV), Open Circuit Potential (OCP), and Electrochemical Impedance Spectroscopy (EIS), while mechanical performance was evaluated through tensile testing. The coating’s thickness, surface roughness, water contact angle, and composition were characterised to understand its protective behaviour. The results show that the coating significantly reduced corrosion rates, with carbon steel exhibiting a 99.99% inhibition efficiency and aluminium showing the lowest corrosion rate due to a synergistic effect between the coating and native oxide layer. Mechanical testing revealed that coated carbon steel retained higher tensile strength and stiffness compared to its uncoated counterpart, while aluminium showed notable recovery in elastic modulus. Copper displayed minimal mechanical changes due to its inherent corrosion resistance. This work highlights the potential of eco-friendly coatings in enhancing both the corrosion resistance and mechanical durability of metallic materials in aggressive environments. Full article

The present paper deals with the combined application of near-surface geophysical techniques in a sustainable agriculture project. Their application is focused on the identification of any subsurface water in the context of sustainable water management for the selected living hub, located in the semi-arid area of Agios Georgios-Mandra Attiki. The objective of the multidisciplinary geophysical study was to determine the depth of the bedrock and the thickness of the post-Alpine deposits. In addition, the subsurface karstification and the possible aquifer presence were examined. For that reason, the following techniques were implemented: Electrical Resistivity Tomography, Seismic Refraction Tomography, Ground-Penetrating Radar, and Very-Low Frequency electromagnetic technique. The study was also supported by drone LiDAR usage. The investigation revealed several hydrogeological characteristics of the area. The thickness of the post-Alpine sediments is almost 3 m. However, no shallow aquiferous systems have been developed in this formation, as indicated by their relatively high resistivity values (100–1000 Ohm.m). Furthermore, the alpine bedrock exhibits extensive karstification, facilitated by the development of fracture zones. The absence of an underlying impermeable layer prevented the development of aquiferous zones, at least up to a depth of 100 m. Full article

The formation of metal–polymer composites by 3D printing PLA and PETG onto EN AW-5182 H111 aluminum substrates without the use of adhesives was investigated. Four surface treatments were evaluated on the metal substrate (fine sanding, coarse sanding, abrasive blasting, and acid etching), over which a polymer primer—prepared from PLA and PETG solutions—was applied. Subsequently, test specimens were fabricated using the same polymer through material extrusion (MEX) with filaments. Adhesion strength between the printed polymer and the metal substrate was assessed through perpendicular tensile, lap shear, and three-point bending tests. The 16-condition experimental matrix combined surface treatment, primer thickness, and bed temperature and was replicated for each test. Peak tensile and shear strengths confirmed the effectiveness of the proposed strategy, with PETG consistently showing a higher interfacial performance than PLA. ANOVA analysis identifies primer layer thickness (p = 0.023) and loading type (p = 0.031) as statistically significant variables. The results suggest that either abrasive or acid pretreatment, combined with a primer thickness ≥ 80 µm and moderate bed temperatures (65 °C for PLA and 90 °C for PETG), enables the fabrication of robust metal–polymer joints, which are particularly resistant to shear stress and suitable for industrial applications. Full article

Anodised metal matrices represent a versatile and multifunctional platform for the development of advanced materials with tunable physicochemical properties. Through electrochemical oxidation processes—commonly referred to as anodisation—metals such as aluminium, titanium, niobium, zinc and tantalum can be transformed into structured oxide layers with defined porosity, thickness and surface morphology. These methods enable the fabrication of ordered nanoporous arrays, nanotubes and nanowires, depending on the process parameters and the type of metal. The review introduces and outlines the various anodisation techniques and parameters. This is crucial, since each individual metal requires specified optimal conditions to obtain a stable anodised oxide layer. This review provides an overview of recent advances in the design and application of anodised metal substrates, with the focus on their role as functional platforms in catalysis, sensing, energy storage and biomedical engineering. Special attention is given to post-anodisation surface modification strategies, such as chemical functionalisation, thin-film deposition and molecular-level integration, which significantly expand the utility of these materials. The review also highlights the challenges, limitations and future perspectives of anodising technologies, aiming to guide the rational design of next-generation devices based on engineered oxide architectures. Full article

This study investigates the critical influence of oxidation temperature on the intrinsic characteristics and surface properties of thermally oxidized Zr2.5Nb alloy. The resulting oxide layers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), surface hardness, and nanoindentation. The tribological behavior of the untreated and thermally oxidized Zr2.5Nb alloy was evaluated via reciprocating ball-on-disc wear tests under a load of 29.4 N. MC3T3-E1 cells were employed to assess the biocompatibility. The results show that oxide layers primarily composed of m-ZrO₂ formed on the alloy surface, with thickness increasing from 2.43 µm to 13.59 µm as the oxidation temperature rose from 500 °C to 700 °C. However, this thickness increase was accompanied by elevated defect density. Compared to the untreated alloy, thermally oxidized samples exhibited significantly enhanced hardness and wear resistance. Notably, oxidation at 600 °C produced a dense 5.31 µm oxide layer with optimal structural integrity, achieving an 85% reduction in wear rate and a superior MC3T3-E1 cell relative activity of 123.07 ± 6.02%. These findings provide foundational data for developing zirconium-based implants with improved stability. Full article