Search Results (2,003)

Protective coatings are essential for extending the service life of components exposed to harsh conditions, such as pipes used in industrial systems, where wear and corrosion remain constant challenges. This study explores the development of a nano-sized TiO₂-reinforced electroless nickel-based ternary (Ni-W-P) alloy and composite coating on API X60 steel, a high-strength carbon steel pipe grade widely used in oil and gas pipelines, using an alkaline hypophosphite-reduced bath. The surface morphology, microstructure, elemental composition, structure, phase evolution, adhesion, and roughness of the coatings were analyzed using optical microscopy, FESEM, EDS, XRD, AFM, cross-cut tape test, and 3D profilometry. The tribological performance was evaluated via Vickers microhardness measurements and reciprocating wear tests conducted under dry conditions at a 5 N load. The TiO₂ nanoparticle-reinforced composite coating achieved a consistent thickness of approximately 24 µm and exhibited enhanced microhardness and reduced coefficient of friction (COF), although the addition of nanoparticles increased surface roughness (S_a). Annealing the electroless composites at 400 °C led to a significant improvement in their tribological properties, primarily owing to the grain growth, phase transformation, and Ni₃P crystallization. XRD analysis revealed phase evolution from an amorphous state to crystalline Ni₃P upon annealing. Both the alloy and composite coatings exhibited excellent adhesion performances. The combined effect of TiO₂ nanoparticles, tungsten, and Ni₃P crystallization greatly improved the wear resistance, with abrasive and adhesive wear identified as the dominant mechanisms, making these coatings well suited for high-wear applications. Full article

As austempered ductile iron (ADI) is a key gear material for meeting the lightweight and cost-effective demands of new energy vehicles, its bending fatigue performance has a direct impact on vehicle transmission efficiency. In the present work, QTD 800 gears were subjected to bending fatigue testing using a combination of the conventional group method and the staircase method, with considerations given to fatigue life and fatigue limit at different reliability levels. Subsequently, the gears were characterized using optical microscopy and a microhardness tester to examine their metallographic structure and determine their hardness. The results indicate that the bending fatigue limits corresponding to gear reliability levels of 50%, 90%, and 99% are 390.00 MPa, 372.55 MPa, and 358.32 MPa, respectively. It was also observed that higher gear life stability corresponds to a lower sustainable fatigue limit stress. The analyses further reveal that under low loads, the main crack exhibits a relatively straight and smooth propagation trajectory, formed through the slow extension of an existing crack, whereas under high loads, the main crack displays a rough and serrated appearance, arising from the coalescence of microcracks initiated around graphite nodules. Full article

In this study, a diamond/diamond-like carbon (DLC) composite coating was designed and fabricated utilizing a combination of chemical vapor deposition (CVD) and magnetron-sputtering-assisted ion beam deposition. This was designed to cope with severe problems such as high wear due to insufficient lubrication under dry sliding conditions with a single diamond. The tribological properties of the fabricated coatings under dry conditions were comparatively evaluated. The results demonstrate that the diamond/DLC composite coatings significantly enhance the tribological performance relative to their single-layer diamond counterparts. Specifically, a 33.73% reduction in the average friction coefficient and a 39.55% decrease in the average wear rate were observed with the MCD (microcrystalline diamond/DLC coating. Similarly, a 16.85% reduction in the average friction coefficient and a 9.69% decrease in the average wear rate were observed with the UNCD (ultrananocrystalline diamond)/DLC coating. Analysis of the worn track morphology and structure elucidated the underlying friction mechanism. It is proposed that the DLC top layer reduces the surface roughness of the underlying diamond coating and mitigates abrasive wear in the dry environment. Furthermore, the presence of the DLC film promotes graphitization via phase transition during sliding, which enhances lubricity and facilitates the establishment of a smooth friction interface. Full article

Burnishing is a critical surface finishing process that uses a hard tool to apply pressure on the surface, lasting one or multiple passes to plastically deform surface asperities on high-performance alloys like 42CrMo4 steel. But the conventional method fails to efficiently enhance surface properties by selecting specifically the values of feed in all passes that follow the same path, missing uneven asperities. In this study, surfaces are burnished with multiple passes by changing the feed in each pass, hypothesizing that the approach can optimize the plastic deformation mechanism. By applying this approach, the tool’s path is deviated from its previous path to enhance the surface integrity by targeting residual surface anomalies. Controlled four levels of forces (60, 90, 120, 150 N), four feed levels (0.02, 0.08, 0.14, and 0.2 mm/rev), and three levels of passes (2, 3, 4) were applied on the proposed method and the conventional method to evaluate and compare their effects. Experimental results confirmed better surface roughness by the varying feed approach, demonstrating its efficacy in enhancing finishing quality through controlled plastic deformation. The analyzed S_a, S_sk, S_ku, S_k, S_pk, and S_vk showed changed topography by both methods, specifically 0.02 mm/rev feed in the old and feed combination in the feed-varying method, which included 0.02 mm/rev, produced smoother surfaces, but the highest elapsed time. The findings generally highlight the potential of adaptive feed strategies to overcome limitations of conventional burnishing, offering a viable solution for precision finishing of high-performance alloys. Full article

The nanoporous structure of coal is crucial for the occurrence and development of coalbed methane (CBM). This study, leveraging the combined characterization of atomic force microscopy (AFM) and Gwyddion software (v2.62), investigated six anthracite samples with varying degrees of metamorphism (R_o = 2.11–3.36%). It revealed the intrinsic relationships between their nanoporous structures, surface morphologies, fractal characteristics, and coalification processes. The research found that as R_o increases, the surface relief of coal decreases significantly, with pore structures evolving from being macropore-dominated to micropore-enriched, and the surface tending towards smoothness. Surface roughness parameters (R_a, R_q) exhibit a negative correlation with R_o. Quantitative data indicate that area porosity, pore count, and shape factor positively correlate with metamorphic grade, while mean pore diameter negatively correlates with it. The fractal dimensions calculated using the variance partition method, cube-counting method, triangular prism measurement method, and power spectrum method all show nonlinear correlations with R_o, moisture (M_ad), ash content (A_ad), and volatile matter (V_daf). Among these, the fractal dimension obtained by the triangular prism measurement method has the highest correlation with R_o, A_ad, and V_daf, while the variance partition method shows the highest correlation with M_ad. This study clarifies the regulatory mechanisms of coalification on the evolution of nanoporous structures and surface properties, providing a crucial theoretical foundation for the precise evaluation and efficient exploitation strategies of CBM reservoirs. Full article

Periodontal disease in dogs leads to progressive bone loss and adversely impacts overall health. However, cost-effective regenerative strategies are still limited in veterinary practice. This study aimed to develop and evaluate a novel tannic acid (TA)–gelatin-based hydrogel (Gel), incorporating graphene oxide (GO) and hydroxyapatite nanoparticles (HA), as a potential barrier material for guided tissue regeneration (GTR) applications. The hydrogels—Gel, Gel-GO, Gel-HA, and Gel-GO-HA—were characterized for chemical structure, molecular interactions, surface morphology, nanoparticle dispersion, and tensile strength. Cytotoxicity was assessed using L929 fibroblasts (ISO 10993-5), while cell viability/proliferation, morphology, and alkaline phosphatase (ALP) production were evaluated using canine periodontal ligament-derived cells. Results show that crosslinking with tannic acid enhanced the incorporation of graphene oxide and hydroxyapatite nanoparticles via hydrogen bonding into TA–gelatin-based hydrogels. This combination increased surface roughness, reduced degradation rate, and enabled shape memory behavior, critical for guided tissue regeneration (GTR) membranes. The extracts from Gel-HA-GO showed that cytotoxicity was both time- and concentration-dependent in L929 fibroblasts, whereas enhanced cell proliferation and increased ALP production were observed in cultures derived from canine periodontal ligament cells. These findings suggest that TA–gelatin-based hydrogels incorporating GO and HA demonstrated favorable mechanical and physicochemical properties, biocompatibility, and osteogenic potential. These attributes suggest their viability as a promising composite for the development of innovative GTR strategies to address periodontal tissue loss in veterinary medicine. Full article

Background: Atrial fibrillation (AF) is common complication of heart failure with preserved ejection fraction (HFpEF) that sufficiently intervenes in the prognosis. The aim of the study is a) to investigate the possible discriminative value of adropin for newly onset AF in patients with HFpEF without a previous history of AF and who are being treated in accordance with conventional guideline and b) to compare it with predictive potencies of conventionally used predictors. Methods: A total of 953 patients with HFpEF who had sinus rhythm on ECG were enrolled in the study. The course of the observation was 3 years. Echocardiography and assessment of conventional hematological, biochemical parameters and biomarker assay including N-terminal brain natriuretic pro-peptide (NT-proBNP), high-sensitivity cardiac troponin T, tumor necrosis factor-alpha, high-sensitivity C-reactive protein (hs-CRP), galectin-3, interleukin-6, soluble suppressor tumorigenisity-2 (sST2) and adropin, were performed at baseline. Results: Incident atrial fibrillation was found in 172 patients with HFpEF, whereas 781 had sinus rhythm. In unadjusted rough Cox regression model, age ≥ 75 years, type 2 diabetes mellitus, chronic kidney disease (CKD) stages 1–3, left atrial volume index (LAVI) ≥ 40 mL/m², NT-proBNP ≥ 1440 pmol/mL, hs-CRP ≥ 5.40 mg/L, adropin ≤ 2.95 ng/mL, sST2 ≥ 15.5 ng/mL were identified as the predictors for new onset AF in HFpEF patients. After adjusting for age ≥ 75 years, a presence of type 2 diabetes mellitus and CKD stages 1–3, the levels of NT-proBNP ≥ 1440 pmol/mL and adropin ≤ 2.95 ng/mL were independent predictors of new onset AF in patients HFpEF. We also found that discriminative value of adropin was superior to NT-proBNP, while adding adropin to NT-proBNP did not improve predictive information of adropin alone. Conclusions: adropin ≤ 2.95 ng/mL presented more predictive information than NT-proBNP ≥ 1440 pmol/mL alone for new cases of AF in symptomatic patients with HFpEF, whereas the combination of both biomarkers did not improve the predictive ability of adropin alone. Full article

To investigate how sand erosion impacts the anti-icing performance of wind turbine blade surfaces, this study experimentally examines the individual and interactive effects of four key factors—the freezing temperature, separation temperature, surface roughness of eroded blade coatings, and loading rate on ice adhesion properties.The results from single-factor analyses reveal that the ice adhesion strength increases linearly with decreasing separation temperature. A more nuanced relationship emerges when considering the freezing temperature relative to the separation temperature: when the freezing temperature exceeds the separation temperature, the adhesion strength rises linearly as the separation temperature drops; conversely, when the freezing temperature is lower than the separation temperature, the adhesion strength decreases linearly with falling separation temperature. Higher loading rates correlate with reduced ice adhesion, while increased surface roughness induced by sand erosion leads to greater adhesion strength. Orthogonal array testing demonstrates the hierarchy of these factors’ influence on post-erosion ice adhesion, as follows: separation temperature > loading rate > freezing temperature > surface roughness of sand-eroded coatings. Notably, the separation temperature and loading rate exert the most significant effects. Furthermore, a regression equation for ice adhesion strength is established based on orthogonal test results, which can effectively predict ice adhesion strength under untested parameter combinations. These findings provide critical foundational data and a reliable theoretical tool to inform the development and optimization of practical de-icing systems in engineering applications. Full article

Titanium alloys (Ti-6Al-4V) are widely used in the aerospace field. However, as a typical difficult-to-machine material, titanium alloys have a low thermal conductivity, a high chemical activity, and a significant adiabatic shear effect. In conventional milling (CM), the temperature in the cutting zone rises sharply, leading to tool adhesion, rapid wear, and damage to the workpiece surface. This article systematically investigated the influence of process parameters on the surface roughness, cutting force, and cutting temperature in the ultrasonic-vibration-assisted milling (UAM) process of titanium alloys, based on which multi-objective optimization process of the milling process parameters was conducted, by utilizing the grey relational analysis method. An orthogonal experiment with four factors and four levels was conducted. The effects of various process parameters on the surface roughness, cutting force, and cutting temperature were systematically analyzed for both UAM and CM. The grey relational analysis method was employed to transform the optimization problem of multiple process target parameters into a single-objective grey relational degree optimization problem. The optimized parameter combination was as follows: an ultrasonic amplitude of 6 μm, a spindle speed of 6000 rpm, a cutting depth of 0.20 mm, and a feed rate of 200 mm/min. The experimental results indicated that the surface roughness Sa was 0.268 μm, the cutting temperature was 255.39 °C, the cutting force in the X direction (FX) was 5.2 N, the cutting force in the Y direction (FY) was 7.9 N, and the cutting force in the Z direction (FZ) was 6.4 N. The optimization scheme significantly improved the machining quality and reduced both the cutting forces and the cutting temperature. Full article

Leaf Area Index (LAI) is a critical biophysical parameter for characterizing vegetation canopy structure and function. However, fine-scale LAI estimation remains challenging due to limitations in spatial resolution and structural detail in traditional remote sensing data and the insufficiency of single-index models like the LiDAR Penetration Index (LPI) in capturing canopy complexity. This study proposes a multi-scale LAI estimation approach integrating high-density UAV-based LiDAR data with LPI and point cloud texture features. A total of 40 field-sampled plots were used to develop and validate the model. LPI was computed at three spatial scales (5 m, 10 m, and 15 m) and corrected using a scale-specific adjustment coefficient (μ). Texture features including roughness and curvature were extracted and combined with LPI in a multiple linear regression model. Results showed that μ = 15 provided the optimal LPI correction, with the 10 m scale yielding the best model performance (R² = 0.40, RMSE = 0.35). Incorporating texture features moderately improved estimation accuracy (R² = 0.49, RMSE = 0.32). The findings confirm that integrating structural metrics enhances LAI prediction and that spatial scale selection is crucial, with 10 m identified as optimal for this study area. This method offers a practical and scalable solution for improving LAI retrieval using UAV-based LiDAR in heterogeneous forest environments. Full article

A single-crystal magnesium oxide (MgO) dual-Fabry–Perot (FP)-cavity sensor based on MEMS technology and laser micromachining is proposed for simultaneous measurement of temperature and pressure. The pressure sensitive cavity is processed by wet chemical etching and direct bonding, which can improve machining efficiency, ensure the quality of the reflection surface and achieve thermal stress matching. Femtosecond laser and micromachining technologies are used to fabricate a rough surface and a through hole to reduce the reflect surface and fix the optical fiber. The bottom surface of the pressure cavity and the upper surface of the MgO wafer form a temperature cavity. A cross-correlation signal demodulation algorithm combined with a temperature decoupling method is proposed to achieve dual-cavity demodulation and eliminate the cross-sensitivity between temperature and pressure, improving the accuracy of pressure measurement. Experimental results show that the proposed sensor can stably operate at an ambient environment of 22–800 °C and 0–0.5 MPa with a pressure sensitivity of approximately 0.20 µm/MPa (room temperature), a repeatability error of 2.06% and a hysteresis error of 1.90%. After temperature compensation, thermal crosstalk is effectively eliminated and the pressure measurement accuracy is 2.01%F.S. Full article

Rail corrugation and roughness represent typical irregularities on railway and tramway tracks, which cause increased dynamic forces, high-frequency vibrations, reduced riding comfort, shorter track lifespan, higher maintenance costs, and increased noise levels. Roughness and corrugation can be measured by evaluating the unevenness of the rail longitudinal running surface, which can be conducted using handheld devices or trolleys (directly on the track). Alternatively, vehicle or track-based indirect methods offer practical solutions for determining the condition of the rail running surface. This paper presents a methodology for rail corrugation and roughness evaluation, using bogie frame vibration data from an instrumented in-service tramway vehicle operating on Zagreb’s tramway network. Furthermore, it investigates the effects of various factors on the evaluation method, including wheel roughness, lateral positioning, signal processing methods, horizontal geometry, wheel–rail contact force, and tramway vehicle vibroacoustic characteristics. It was concluded that a simplified methodology that did not include transfer functions or wheel roughness measurements yielded relatively good results for evaluating rail corrugation and roughness across several wavelength bands. To improve the presented methodology, future research should assess the vehicle’s vibroacoustic characteristics with experimental hammer impact tests, measure the influence of wheel roughness on wheel–rail contact and bogie vibrations, and refine the measurement campaign by increasing test runs, limiting speed variation, and conducting controlled tests. Full article

Melanoma is one of the most invasive skin cancers with the highest mortality risk. The PI3K/AKT/mTOR signaling pathways are a key regulatory point related to growth factors and involved in the cell’s energy metabolism. They are responsible for cell life processes such as growth, proliferation, invasion, survival, apoptosis, autophagy, and angiogenesis. The studies undertaken concerned the effect of protein kinase inhibitors involved in the signaling pathways of AKT, MEK, and mTOR kinases on the expression of cytoskeletal and extracellular matrix proteins, invasion process, and activities of the matrix metalloproteinases (MMPs): MMP-2 and MMP-9 in melanoma cells. The study used mTOR kinase inhibitors: Everolimus and Torkinib; dual PI3K/mTOR inhibitors BEZ-235 and Omipalisib; and the mTORC1/2 inhibitor OSI-027. These compounds were used both as monotherapy and in combination with the MEK1/2 inhibitor AS-703026. mTOR kinase inhibitors, especially the third generation in combination with the MEK 1/2 kinase inhibitor AS-703026, significantly inhibited invasion and metalloproteinases (MMPs) activity in melanoma cell lines. The inhibition of the cell invasion process was accompanied by a significant change in the expression of proteins associated with EMT. The morphology of cells also changed significantly: their thickness, volume, roughness, convexity of shape, and irregularity, which may be a good diagnostic and prognostic factor for the response to treatment. Our studies to date on the effect of three generations of mTOR kinase inhibitors on the inhibition of the invasion process, the activation of apoptosis, and the reduction in cell proliferation suggest that they may be an important target for anticancer therapy. Full article

Technological advances have expanded the use of single-crystal in microscale applications—particularly in infrared optics, electronics, and aerospace. Conducting research on the surface quality of micro-milling processes for single-crystal superalloys has become a key factor in expanding their applications. In this paper, the nickel-based single-crystal superalloy DD5 is selected as the test object, and the finite element analysis software ABAQUS 2022 version is used to conduct a simulation study on its micro-scale milling process with reasonable milling parameters. A three-factor five-level L₂₅(5³) slot milling orthogonal experiment is conducted to investigate the effects of milling speed, milling depth, and feed rate on its milling force and surface quality, respectively. The results show that the milling depth has the greatest impact on the milling force during the micro-milling process, while the milling speed has the greatest influence on the surface quality. Finally, based on the experimental data, the optimal parameter combination for micro-milling nickel-based single-crystal superalloy DD5 parts is found—when the milling speed is 1318.8 mm/s; the milling depth is 12 µm; the feed rate is 20 µm/s; and the surface roughness value is at its minimum, indicating the best surface quality—which has certain guiding significance for practical machining. Full article

As global industries seek to reduce energy consumption and lower CO₂ emissions, the need for sustainable, efficient maintenance processes in manufacturing has become increasingly important. Traditional mold cleaning methods often require complete tool disassembly, extended downtime, and heavy use of solvents, resulting in high energy costs and environmental impact. This study presents a novel localized ultrasonic cleaning process for injection molding tools that enables targeted, in situ cleaning of mold cavities without removing the tool from the press. A precisely positioned ultrasonic transducer delivers cleaning energy directly to contaminated areas, eliminating the need for complete mold removal. Multiple cleaning agents, including alkaline and organic acid solutions, were evaluated for their effectiveness in combination with ultrasonic excitation. Surface roughness measurements were used to assess cleaning performance over repeated contamination and cleaning cycles. Although initial tests were performed manually in the lab, results indicate that the method can be scaled up and automated effectively. This process offers a promising path toward energy-efficient, low-emission tool maintenance across a wide range of injection molding applications. Full article