Search Results (28,979)

The tribological behavior of ferritic ductile iron without ultrafine graphite nodules (FDI) and ferritic ductile iron with ultrafine graphite nodules (FDI-UG) was investigated in the present study. Ultrafine graphite nodules with a count of 3400 nod/mm² were introduced by annealing treatment of quenched ductile iron, which effectively reduced the friction coefficient of ferritic ductile iron from approximately 0.3 to 0.15. This improvement was attributed to the ultrafine graphite nodules, which, due to their small spacing, facilitated a more uniform distribution on the tribological surface. Additionally, the formation of ultrafine graphite nodules in ferritized ductile iron refined the grain size (15 μm) and enhanced the hardness of ferritic ductile iron (183 HV), thereby significantly reducing abrasive wear. The more uniform graphite lubrication on the tribosurface and high hardness of fine ferrite grains in FDI-UG further enhanced wear resistance between the frictional pairs, effectively suppressing adhesion wear at high loads (6 N). Consequently, the ferritic ductile iron containing ultrafine graphite nodules and fine ferrite grains exhibited a superior wear resistance (6.84 × 10⁻³ mm³ and 9.47 × 10⁻³ mm³) compared to its untreated counterpart (9.22 × 10⁻³ mm³ and 11.95 × 10⁻³ mm³). These findings suggest that the incorporation of ultrafine graphite nodules was an effective strategy to enhance the tribological properties of ductile iron. Full article

The paper systematically investigated the flotation behavior and interaction mechanisms of andalusite and quartz under sodium dodecyl sulfonate (SDS) through integrated experimental and computational approaches, including zeta potential measurements, Fourier-transform infrared (FTIR) spectroscopy, Materials Studio (MS)-based quantum chemical calculations, and single-mineral flotation tests. The results of zeta potential and infrared spectroscopy analysis indicated that SDS underwent strong chemical adsorption on the surface of andalusite, while the adsorption effect on the surface of quartz was not obvious. MS calculations showed that the {100} surface energy of andalusite was the lowest, and it was the most important dissociation surface. After SDS was adsorbed on the {100} surface of andalusite, the aluminum atoms on the surface of andalusite lost electrons, resulting in a significant increase in the number of positive charges they carried. The activity of oxygen atoms was enhanced, while the number of charges carried by silicon atoms changed relatively little. It was indicated that SDS adsorbed the active sites of Al atoms on the surface of andalusite. The results of the pure mineral flotation test further verified the accuracy of the previous test results, indicating that andalusite and quartz had a good flotation separation effect under the SDS system. Full article

This work pioneers the novel application of surface friction treatment (SFT) to sintered porous metals to fabricate gradient-structured functional surfaces. The results demonstrate that SFT significantly modifies surface pore architecture, with scanning velocity and normal load critically controlling gradient layer formation. Excessive parameters induce periodic surface cracking due to mechanical overloading. Post-treatment, the porous metal exhibits a 37.5% reduction in maximum pore size (24 μm to 15 μm) and substantially improved surface finish, with arithmetic mean roughness (Ra) decreasing from 23.8 μm to 4.3 μm (82% reduction). These surface enhancements significantly improve filtration functionality while providing a cost-effective alternative to conventional gradient layer fabrication methods. Full article

Rapid urbanization in semi-arid heritage cities is accelerating land use/land cover (LULC) transitions, with critical implications for local climate regulation, surface energy balance, and environmental sustainability. This study investigates Jaipur, Jodhpur, and Udaipur (Rajasthan, India) between 2018 and 2024 to assess the influence of spatio-temporal dynamics of LULC on urban surface metrics. Multi-temporal satellite datasets were used to derive the index-based built-up index (IBI), surface urban heat island intensity (SUHI), Albedo, urban thermal field variance index (UTFVI), and bare soil index (BSI). The results reveal substantial built-up expansion—most pronounced in Udaipur (+26.7%)—coupled with vegetation loss (up to −23.8% in Jaipur) and progressive albedo decline (Sen’s slope ≈ −0.002 yr⁻¹). These transformations highlight suppressed surface reflectivity and enhanced heat absorption. A key and novel finding is the emergence of a counter-intuitive surface urban cool island (SUCI) effect, whereby urban cores exhibited daytime cooling and nighttime warming relative to rural surroundings. This anomaly is attributed to the rapid heating and poor nocturnal heat retention of bare, sparsely vegetated rural soils, contrasted with the thermal inertia and shading of urban surfaces. By documenting negative SUHI patterns and explicitly linking them to LULC trajectories, this study advances the understanding of urban climate dynamics in semi-arid contexts. The findings underscore the need for climate-sensitive planning—strengthening peri-urban green belts, regulating impervious expansion, and adopting albedo-enhancing construction materials—while safeguarding cultural heritage. More broadly, the study contributes empirical evidence from climatically vulnerable yet culturally significant cities, offering insights relevant to global SUHI research and sustainable urban development. Full article

The anodic oxidation technique was used for surface modification, resulting in the creation of a titanium-based nanotube oxide layer on a coarse-grained and ultrafine-grained Ti-13Nb-13Zr alloy. The modified surface morphology was analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). The electrochemical impedance spectroscopy (EIS) method was employed to evaluate the corrosion stability of the Ti-13Nb-13Zr alloy before and after anodic oxidation. Corrosion stability was determined by exposing the examined alloy to a solution that simulates environment in the human organism (Ringer’s solution). To examine the titanium-based nanotube oxide layer adhesion on the Ti-13Nb-13Zr alloy’s surface, a scratch test was performed. The hydrophilicity of the modified surface was measured using the contact angle between a drop of Ringer’s solution and the modified surface. The anodic oxidation led to the creation of a nanotube oxide layer on the surface of the Ti-13Nb-13Zr (wt.%) alloy. The impact of the ultrafine-grained structure on the homogeneity of the nanotube oxide layer obtained using anodic oxidation was observed. The ultrafine-grained structure contributed to the increased diameter of the nanotubes, while the combined effect of anodic oxidation and high-pressure torsion significantly increased the roughness of the Ti-13Nb-13Zr alloy’s surface, which is expected to enhance biomechanical compatibility by reducing cytotoxicity, providing a more adaptable modulus of elasticity for human body conditions and ensuring adequate corrosion resistance and hydrophilicity. In this study, it was established that the examined alloy had suitable corrosion resistance for utilization in medicine as a metallic implant in the human body. The scratch test showed acceptable adhesion from the titanium-based nanotube oxide layer created using anodic oxidation. Also, the determination of the surface contact angle showed that the surface after anodic oxidation was more hydrophilic than the surface before anodic oxidation. Full article

Peridynamics (PD) exhibits inherent advantages in solving solid mechanics problems involving strong discontinuities, such as crack propagation. However, the significant magnitude discrepancy between the micro-modulus and bond stretch in the nonlocal modelling, the extensive accumulation operations during nonlocal interaction integration, and the calculation methods for surface-correction coefficients can all introduce or amplify numerical errors, thereby reducing the confidence in numerical results. To address these sources of error and enhance the numerical accuracy of the PD models, this study derived a dimensionless bond-based PD formulation and proposed computational strategies to mitigate numerical errors during model implementation. The correctness of the dimensionless bond-based PD model was validated through investigating an elastic-wave propagation problem and a crack-branching problem, and comparing the numerical results with that from the finite-element method and the referenced literature. The effectiveness of the dimensionless model and the numerical strategies in enhancing numerical accuracy was verified through comparing the numerical performance of the model while investigating symmetrical mechanical problems under extreme computational conditions and load conditions. This study provides an effective modelling framework and numerical processing strategies for accurate computations in PD. Full article

The optimization of polymer extrusion processes is crucial for improving product quality and manufacturing efficiency in plastic industries. This study aims to investigate the viscoelastic flow behavior of high-density polyethylene (HDPE) through an extrusion die with an internal mandrel, focusing on the effects of die geometry and flow parameters. A two-dimensional (2D) numerical model is developed in COMSOL Multiphysics using the Oldroyd-B constitutive equation, solved using the Galerkin/least-square finite element method. The simulation results indicate that the Weissenberg number (Wi) and die geometry significantly influence the dimensionless drag coefficient (Cd) and viscoelastic stress distribution along the die wall. Furthermore, filleting sharp edges of the die wall surface effectively reduces stress oscillations, enhancing flow uniformity. These findings provide valuable insights for optimizing die design and improving polymer extrusion efficiency. Full article

Background/Objectives: Cervical cancer remains a major health challenge, especially in low-resource regions with limited diagnostic and advanced treatment options. Nanotechnology-based strategies offer promising alternatives to conventional chemotherapy by reducing systemic toxicity and enabling site-specific delivery. Methods: In this study, halloysite (Hall) was functionalized with green-synthesized 2 wt% zinc oxide (GZn) and silver (GAg) nanoparticles (NPs) using Tribulus terrestris extract (25 mM) to enhance cisplatin (Cp) and carboplatin (Cbpt) delivery for targeted cervical cancer therapy. Results: Structural and morphological analyses confirmed the successful integration of GZn and GAg NPs into the Hall without compromising its tubular integrity. Cp or Cbpt adsorption studies with varying times (0.15–12 h), as well as drug/Hall ratios (10–50) and pH levels (5; 6.6; 7.4; 9.0; and 10.5), revealed greater Cp adsorption than Cbpt, attributed to its higher reactivity and affinity toward the Hall surface. pH-responsive release studies biphasic drug release for non-PEGYlated formulations, with Cp (14% with 2 h) and Cbpt (10% with 0.5 h), whereas PEGYlated systems exhibited sustained release under acidic tumor-like conditions, achieving 14% in 72 h for Cp and 4.5% in 72 h for Cbpt. Release kinetics followed either Fickian or non-Fickian diffusion depending on pH and drug type, with the Korsmeyer–Peppas model offering a strong fit (R² > 0.85). In vitro assays revealed that Cbpt/GZn-Hall/PEG, Cp/GZn-Hall/PEG, and Cbpt/GAg-Hall/PEG induced dose-dependent cytotoxicity against HeLa while sparing HFF-1 fibroblasts. Conclusions: These findings indicate that green-synthesized nanohybrids are promising carriers for targeted Cp and Cbpt delivery, warranting further in vivo evaluation for cervical cancer therapy. Full article

Earthen final covers (EFCs) are widely used to mitigate environmental impacts from landfills, particularly in controlling methane emissions and groundwater contamination. In this study, a one-dimensional numerical model was built to simulate the interactions of liquid water, water vapor, landfill gas, and heat, incorporating the biochemical process of methane oxidation. Parametric studies revealed that both atmospheric and waste temperatures significantly influence the soil temperature and evaporation, thereby affecting methane oxidation. Oxidation efficiency increased from 8.7% to 55.3% as atmospheric temperature rose from 5 °C to 35 °C. High waste temperatures enhanced oxidation by up to 2.9 times under cold conditions. An increase in atmospheric pressure (950–990 mbar) promoted oxygen diffusion into the cover and improved oxidation efficiency from 0.8% to 77.1%. Atmospheric relative humidity also played a critical role by affecting surface evaporation, with higher humidity promoting better water retention but limiting oxygen diffusion. The methane oxidation performance of the cover declined by 12.0% to 68.5% compared to pre-rainfall conditions. Rainfall temporarily inhibited oxidation due to moisture-induced oxygen limitation, with partial recovery after rainfall ceased. This study provided valuable insights into the complex interactions between ambient conditions and EFC performance, contributing to the optimization of landfill cover designs and methane mitigation strategies. Full article

The Wolf Motor Function Test (WMFT) is widely used to evaluate upper limb motor performance after stroke. However, conventional approaches may overlook domain-specific neuromuscular and kinematic differences during task execution. This study classified WMFT tasks into three functional domains: proximal reaching and transport (PRT), fine motor manipulation (FMM), and gross motor functional control (GMFC). Interlimb differences in muscle activation, joint mobility, and movement amplitude were examined using sensor-based measurements. Twelve individuals with chronic stroke performed 16 WMFT tasks. Surface electromyography (EMG) and inertial measurement units (IMUs) recorded upper limb muscle activity, joint angles, and segmental displacement. Wilcoxon signed-rank tests and Spearman correlations were conducted for each functional domain. Significant asymmetries in EMG, range of motion (ROM), and root mean square (RMS) acceleration were found in PRT and FMM tasks. These results reflect increased proximal muscle activation and reduced distal engagement on the paretic side. GMFC tasks elicited more symmetrical patterns but still showed subtle deficits in distal control. Correlation analyses demonstrated strong interdependencies among neuromuscular and kinematic measures. This finding underscores the integrated nature of compensatory strategies. Categorizing WMFT tasks by functional domain and integrating multimodal sensor analysis revealed nuanced impairment patterns. These patterns were not detectable by conventional observational scoring. These findings support the use of sensor-based, domain-specific assessment to guide individualized rehabilitation strategies. Such approaches may ultimately enhance long-term functional recovery in stroke survivors. Full article

Marine oil spills remain a recurring environmental concern, particularly in coastal and estuarine areas. Among the available strategies for managing spilled oil, sorbents derived from natural fibers have attracted considerable interest as viable alternatives to synthetic materials due to their biodegradability, low cost, and alignment with circular economy principles. This review synthesizes recent advances by connecting technical and environmental aspects with operational applications. It emphasizes structural and surface modifications of lignocellulosic fibers to enhance petroleum sorption capacity, selectivity, buoyancy, and reusability. Physical, chemical, and biological approaches are discussed, focusing on how these modifications influence sorption dynamics under realistic conditions. The review also highlights the incorporation of agricultural and industrial residues as raw materials, along with regeneration and reuse strategies that support waste valorization. However, significant gaps remain, such as the lack of studies with weathered crude oils, the limitation of larger-scale testing, and the need for standardized methods and evaluation of the final fate of exhausted biosorbents. Through the integration of technical, environmental, and operational criteria, this review provides a critical foundation for developing more efficient and circular marine oil spill response technologies. Full article

Composite materials are replacing traditional metals across various industries as they offer lighter weight and affordability, as well as excellent mechanical properties. In the present work, a hybrid composite was developed by combining randomly oriented S-glass fibers and coconut fibers within an epoxy matrix by using the hand lay-up method. The laminate was prepared by using two sheets of raw coconut fiber and eight layers of 200 GSM S-glass fiber, maintaining an epoxy-to-hardener ratio of 10:1. The laminate was cured under a hydraulic press at 80 °C for two hours and then post-cured at a temperature of 100 °C for four hours. In order to assess the performance of the composites, a series of tests, including mode II interlaminar fracture toughness, tensile strength, impact resistance, and hardness, as well as thermal conductivity, were performed. SEM analysis of the fracture surfaces confirmed the combined presence of fiber pull-out and good fiber–matrix bonding, supporting the observed improvements in mechanical properties. The results indicate that the hybrid composite has clear advantages over the composites reinforced with individual fibers alone. It showed a 358% higher tensile strength, a 30% increment in impact strength, and roughly 31% better flexural strength as compared to the coconut fiber composite. In comparison to the glass fiber composite, the hybrid composite offered enhanced toughness and better thermal stability, along with lower material costs and improved sustainability due to the addition of the natural fibers. Considering the rising need for lightweight, strong, and eco-friendly materials for industries, this fabricated hybrid composite appears to be a promising option for structural applications in fields like automotive, aerospace, and construction, where reducing weight without compromising strength is essential. Full article

This study evaluates the application of metal additive manufacturing—specifically the laser powder bed fusion (LPBF) process—for producing aluminium die-casting mould components, comparing 300-grade maraging steel inserts with conventional H13 tool steel. Efficient thermal management and mould durability are critical in aluminium injection moulding. Still, traditional machining limits the design of cooling channels, resulting in hot spots, accelerated wear, and a reduced service life. LPBF allows the fabrication of complex geometries, enabling conformal cooling channels to enhance thermal control. Component samples were manufactured using maraging steel via LPBF, machined to final dimensions, and subjected to duplex surface treatment (plasma nitriding + CrAlN PVD coating). Thermal performance, dimensional stability, mechanical properties, and wear resistance were experimentally assessed under conditions simulating industrial production. The results demonstrate that LPBF components with optimised cooling channels and surface engineering achieve higher thermal efficiency, an extended service life (up to 2.6×), improved hardness profiles (545 HV0.05 core, 1230 HV0.05 on nitrided surface and 2850 HV0.05 after PVD film deposition), and reduced maintenance frequencies compared to H13 inserts. The study confirms that additive manufacturing, combined with tailored surface treatments and optimised cooling design, overcomes the geometric and thermal limitations of conventional manufacturing, offering a reliable and productive solution for aluminium die-casting moulds. Full article

Oily wastewater is a critical environmental concern, and the high costs and fouling of conventional membranes drive the search for low-cost, efficient alternatives. This study evaluates surface-modified quartz particles for oil–water separation, focusing on hydrophilic and hydrophobic coatings. Quartz samples underwent washing, hydrophobic coating, and hydrophilic coating, with morphological and elemental changes assessed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS). Oil and grease (O&G) content was determined via the EPA 1664 method under high-solids conditions. The untreated oil–water mixture contained 142,955.9 mg/L O&G. Hydrophilic-coated quartz achieved the greatest reduction, producing water with only 751.3 mg/L O&G, indicating excellent oil rejection and water selectivity. Washed quartz performed similarly at 837.1 mg/L. Hydrophobic-coated quartz, while yielding higher residual oil in water (64,198.9 mg/L), demonstrated strong oil affinity, making it more suitable for oil recovery applications. Raw quartz, tested without heavy oil loading, showed a baseline of 13.4 mg/L. These results confirm that surface engineering of quartz enables tunable separation properties, where hydrophilic surfaces favor water purification and hydrophobic surfaces enhance oil capture. The findings provide a pathway for scalable, cost-effective, and application-specific oily wastewater treatment solutions. Full article

AuQDs (Au quantum dots) are ultrasmall nanostructures that combine the size-tunable fluorescence and photostability of semiconductor quantum dots with the chemical stability, low toxicity, and versatile surface chemistry of gold nanoparticles. This unique combination endows AuQDs with exceptional biocompatibility and multifunctionality, making them ideal for biomedical applications such as cellular imaging, real-time tracking, targeted drug delivery, diagnostics, therapeutic monitoring, and biosensing. Various synthesis methods—including chemical reduction, hydrothermal, laser ablation, and microwave-assisted techniques—allow for precise control over size and surface properties, optimizing fluorescence and electronic behavior for high-resolution imaging and sensitive detection. Compared to traditional quantum dots, AuQDs offer enhanced safety and biocompatibility, while surpassing larger gold nanoparticles by enabling fluorescence-based imaging. Their surfaces can be functionalized with diverse ligands for targeted delivery and specific biological interactions. In summary, AuQDs are multifunctional nanoprobes that combine superior optical properties, chemical stability, and biocompatibility, making them powerful tools for advanced biomedical diagnostics, therapy, and biosensing. Full article