Search Results (426)

To address the challenges in precision seeding of Cyperus esculentus L. seeds caused by their irregular shape and uneven surface, this study investigates the effect of soaking pretreatment on seed germination and adopts rubber-based seed suction holes to improve adsorption performance. Subsequently, calibration and experiments on discrete element simulation parameters were carried out. Initially, by setting four soaking time gradients (0, 24, 48, and 72 h), the optimal soaking duration was determined. Furthermore, through free-fall collision tests, static friction tests, and rolling friction tests, combined with the Plackett–Burman design, steepest ascent experiments, and Box–Behnken response surface methodology, the contact parameters between seeds and between seeds and rubber suction holes were calibrated and optimized. The results showed that the static friction coefficient (D) between seeds, the rolling friction coefficient (E) between seeds, and the rolling friction coefficient (H) between seeds and rubber have significant effects on the stacking angle. The optimal parameter combination obtained was D = 0.592, E = 0.325, H = 0.171. Validation tests on the dynamic stacking angle demonstrated that the relative error between the simulated and physical test values was only 1.89%, confirming the accuracy of the parameters. This study provides reliable parameter references for the design and simulation optimization of precision seed metering devices for C. esculentus after soaking pretreatment. Full article

The study of Leymus chinensis seed cleaning has been hindered by the lack of accurate discrete-element contact parameters for seed–straw interactions, thereby limiting, to some extent, the optimization of cleaning equipment. To address this issue, the present study analyzed a mixture of L. chinensis seeds and straw, and determined their fundamental physical and contact parameters via laboratory experiments. The Hertz–Mindlin (no slip) discrete element simulation model was employed to calibrate the parameters of the seed–straw mixture. A Plackett–Burman test was used to identify key factors significantly affecting the repose angle, including the seed–seed static friction coefficient and the seed–straw static and dynamic friction coefficients. These factors’ optimal ranges were further refined using steepest ascent experiments. A Box–Behnken design was used to optimize contact parameters, resulting in the following values: a seed–seed static friction coefficient of 0.709, a seed–straw static friction coefficient of 0.281, and a seed–straw dynamic friction coefficient of 0.085. Validation experiments demonstrated an error of less than 2.14%, confirming the reliability of the calibrated parameters. This study offers a theoretical foundation for discrete element simulations in L. chinensis seed cleaning applications. Full article

Addressing the problem of lacking accurate and reliable contact parameters and bonding parameters in the simulation of the mashing process during the harvesting of alfalfa, this study takes the stems of alfalfa at the harvesting stage as the research object. The geometric dimensions and related intrinsic parameters of the stems were measured. Using the Enhanced Discrete Element Method (EDEM) software, a multi-scale discrete element flexible bonding model of alfalfa stems was established based on region-specific parameters. The entire alfalfa stem was divided into three parts: the top, middle, and root sections. A multi-scale particle aggregation model of hollow stems was created using the Hertz-Mindlin with bonding model. The contact parameters between alfalfa stems at the harvesting stage and PU rubber were determined using a mathematical model based on quadratic polynomial fitting curves. The results showed that the shear modulus of the top, middle, and root sections of the alfalfa stems were 24.96 MPa, 29.60 MPa, and 10.48 MPa, respectively. The coefficients of restitution between the top, middle, and root sections of the alfalfa stems and PU rubber were 0.426, 0.375, and 0.386, respectively; the static friction coefficients were 0.613, 0.667, and 0.422, respectively; and the rolling friction coefficients were 0.213, 0.226, and 0.292, respectively. The relative error between the simulated and measured values of the angle of repose was less than 3%, effectively representing the mechanical characteristics of alfalfa stems at the harvesting stage bending and breaking under impact. This study aims to establish a discrete element flexible model of alfalfa stems at the harvesting stage and accurately calibrate the contact parameters with typical rubber materials, thereby addressing the lack of reliable bonding and contact parameters in existing simulations of the mashing process. Full article

The manufacturing industry, in general, and the plastic industry, in particular, have been developing new materials and process methods that need a correct study and optimization. Nowadays, the main approach to optimize these processes is using numerical methods and, in the case of particulate materials, the Discrete Elements Method to estimate the particles interactions. But those mathematical models use some parameters that depend on the material and must be calibrated, thus requiring an important computational and experimental cost. In this study, we integrate different speed-up procedures and present a general calibration method of Low-Density Polyethylene particles, to obtain the calibrated solid density and Poisson’s ratio of the material, the restitution, static and rolling friction factors in the particle-to-particle and particle-to-wall interactions, and the contact model variables (damping factor, stiffness factor, and energy density). For this calibration, four different tests were carried out, both experimentally and with simulations, obtaining the bulk density, the repose and shear angles, and the dropped powder. All these response variables were compared between simulations and experimental tests, and using genetic algorithms, the input parameters (design variables) were calibrated after 85 iterations, obtaining a Mean Absolute Percentage Error of the response variables lower than 2% compared to the experimental results. Full article

The aim of present study is to deposit protective coatings with various surface chemical states on AZ91D Mg alloy. Hydrothermal bioactive ceramic coatings are performed with a surface modification by the chemical bonding of self-assembled monolayers (SAM). The electrochemical corrosion behaviors of various surface-coated AZ91D alloy within DMEM cell culture medium related to their surface chemical states are evaluated through microstructure observations, XPS surface chemical bonding analysis, static contact angles measurements, potentiodynamic polarization curves, and immersion tests. XRD and high resolution XPS of F 1s analysis results show that the hydrothermal FHA coating with a phase composition of Ca₁₀(PO₄)₆(OH)F can be effectively and uniformly deposited on the AZ91D alloy. FHA-coated AZ91D displays better anti-corrosion performances and lower degradation rates than those of uncoated AZ91D alloy in the DMEM solution. Through the high resolution XPS analysis of O 1s and P 2p spectra, it is demonstrated that 1-butylphosphonic acid (BP), 1 octylphosphonic acid (OP), and dodecylphosphonic acid (DP) molecules can be effectively bonded on the FHA surface by a covalent bond to form SAM. BP/OP/DP-SAM specimens display increased static contact angles to show a hydrophobic surface. It demonstrates that the SAM surface treatment can further enhance the corrosion resistance of FHA-coated AZ91D in the DMEM solution. After 2–16 days in vitro immersion tests in the DMEM, the surface SAM-bonded hydrophobic BP/OP/DP-SAM layers can effectively inhibit and reduce the penetration of DMEM into FHA coating. Long alkyl chains of the dodecylphosphonic acid (DP) SAM represents superior enhancing effects on the reduction of corrosion properties and weight loss. Full article

Corona treatment is commonly used in industry to enhance the surface-free energy of plastic films. However, corona treatment may cause some undesirable effects affecting further processing, such as sealing. In this paper, we deeply analyze the corona treatment effect on selected properties of various polymer films commonly used in packaging applications. The films were treated at two power levels (100 W and 300 W), and the experimental design included surface characterization and mechanical testing to assess changes in wettability, chemical structure, and seal strength. The Owens–Wendt approach confirmed the corona treatment effect by static contact angle measurement and surface free energy calculation. Next, their seal strength was evaluated in relation to surface energy and chemical structure changes. FTIR spectroscopy was used to identify functional groups potentially affected by corona treatment. The results indicate that the impact of corona treatment is material-dependent. In general, corona treatment at a lower level increases the seal strength, while corona treatment at a higher power level is related to a decrease in seal strength. The study highlights the importance of optimizing corona treatment parameters for specific materials to enhance seal performance without compromising surface integrity. Full article

Beta (β)-type Ti-29Nb-13Ta-4.6Zr (TNTZ) alloys combine low modulus with biocompatibility but require improved surface properties for long-term implantation. This study aimed to enhance the surface mechanical strength and antibacterial performance of TNTZ by applying TiN and TiAlN coatings via PVD. Notably, TiAlN was deposited on TNTZ for the first time, enabling a direct side-by-side comparison with TiN under identical deposition conditions. Dense TiN (~1.06 μm) and TiAlN (~1.73 μm) coatings were deposited onto solution-treated TNTZ and characterized by X-ray diffraction, scanning probe microscopy, Vickers microhardness, Rockwell indentation test (VDI 3198), static water contact angle measurements, and a Kirby–Bauer disk-diffusion antibacterial assay against Escherichia coli (E. coli). Both coatings formed face-centered cubic (FCC) structures with smooth interfaces (Ra ≤ 5.3 nm) while preserving the single-phase β matrix of the substrate. The hardness increased from 192 HV (uncoated) to 1059 HV (TiN) and 1468 HV (TiAlN), and the adhesion quality was rated as HF2 and HF1, respectively. The surface wettability changed from hydrophilic (48°) to moderately hydrophobic (82°) with TiN and highly hydrophobic (103°) with TiAlN. Similarly, the diameter of the no-growth zones increased to 18.02 mm (TiN) and 19.09 mm (TiAlN) compared to 17.65 mm for uncoated TNTZ. The findings indicate that TiAlN, in particular, provided improved hardness, adhesion, and hydrophobicity. Preliminary bacteriostatic screening under diffusion conditions suggested a modest relative antibacterial response, though the effect was not statistically significant between coated and uncoated TNTZ. Statistical analysis confirmed no significant difference between the groups (p > 0.05), indicating that only a preliminary bacteriostatic trend— rather than a definitive antibacterial effect—was observed. Both nitride coatings strengthened TNTZ without compromising its structural integrity, making TiAlN-coated TNTZ a promising candidate for next-generation orthopedic implants. Full article

This work presents the design and fabrication of microstructured hydrophobic surfaces via fused filament fabrication (FFF) 3D printing with polylactic acid (PLA). Three geometric patterns—triangular-based prisms (TG), truncated pyramids (TP), and truncated ellipsoidal cones (CET)—were developed to modify the surface wettability. Morphological analysis revealed that the printer resolution limits the accurate reproduction of sharp CAD-defined features. Despite this, TG structures exhibited superhydrophobic behavior evaluated through static water contact angles (WCAs), reaching up to 164° along the structured direction and so representing a 100% increase relative to flat PLA surfaces (WCA = 82°). To improve print fidelity, TP and CET geometries with enlarged features were introduced, resulting in contact angles up to 128°, corresponding to a 56% increase in hydrophobicity. The truncated shapes enable the fabrication of the smallest features achievable via the FFF technique, while maintaining good resolution and obtaining higher contact angles. In addition, surface functionalization with fluoropolymer-coated SiO₂ nanoparticles, confirmed by SEM and Raman spectroscopy, led to a further slight enhancement in wettability up to 18% on the structured surfaces. These findings highlight the potential of FFF-based microstructuring, combined with surface treatments, for tailoring the wetting properties of 3D-printed polymeric parts with promising applications in self-cleaning, de-icing, and anti-wetting surfaces. Full article

In view of the problems existing in the application of greenhouse pesticides in China, this paper developed a swing-arm sprayer for greenhouse high-stem crops through field research and a literature review. Static and dynamic simulations of the swing-arm mechanism were carried out to verify the rationality of the structure. The average contact angle between the water and tomato leaves was 49.39°, while the contact angle of the auxiliary solution on the tomato leaves decreased to 40.98°. An indoor atomization test platform was designed to accurately test the particle size and spray performance. The relative span (RS) of droplet distribution showed that the RS values of nozzles 015, 02, and 03 were relatively small, while the RS value of nozzle 04 was about 1.734. With the addition of additives, the RS value of nozzle 02 decreased from 1.305 to 1.021. The field tests showed that the deposition of fog droplets on the front of tomato leaves was in the order of middle > lower > ground > upper (3.622 μL/cm², 3.005 μL/cm², 2.977 μL/cm², and 2.931 μL/cm², respectively). The results indicate that adding additives or increasing the swing-arm angle is beneficial for improving the uniformity of canopy droplet deposition. The front fog droplet coverage of the lower canopy of tomatoes was the lowest, with an average of 26.00%, while the middle and upper canopies had the highest, with an average of 50.58% and 50.72%, respectively. The research found that the spray coverage rate on the front and back sides of tomato leaves was relatively uniform, indicating that the swing-arm greenhouse sprayer designed in this paper could meet the spray quality requirements for tomato pest control. Full article

A quasi-static FEM framework for wheel–rail contact is presented, aimed at large parametric analyses including independently rotating wheel (IRW) configurations. Unlike half-space formulations such as CONTACT, the FEM approach resolves global deformations and strongly non-Hertzian geometries while remaining computationally tractable through three key features: (i) a tailored mesh transition around the contact patch, (ii) solver settings optimized for frictional contact convergence, and (iii) an integrated post-processing pipeline for creep forces, micro-slip, and wear. The model is verified against CONTACT, an established surface-discretization reference based on the Boundary Element Method (BEM), demonstrating close agreement in contact pressure, shear stress, and stick–slip patterns across the Manchester Contact Benchmark cases. Accuracy is quantified using error metrics (MAE, RMSE), with discrepancies analyzed in high-yaw, near-flange conditions. Compared with prior FEM-based contact models, the main contributions are: (i) a rigid–flexible domain partition, which reduces 3D computational cost without compromising local contact accuracy; (ii) a frictionless preconditioning step followed by friction restoration, eliminating artificial shear-induced deformation at first contact and accelerating convergence; (iii) an automated selection of the elastic slip tolerance (slto) based on frictional-energy consistency, ensuring numerical robustness; and (iv) an IRW-oriented parametrization of toe angle, camber, and wheel spacing. The proposed framework provides a robust basis for large-scale studies and can be extended to transient or elastoplastic analyses relevant to dynamic loading, curved tracks, and wheel defects. Full article

PBT/PET side-by-side bicomponent fibers form helical crimp structures under thermal or mechanical stress, though the mechanism behind mechanically induced crimping remains unclear. In this study, four-lobed cross-sectional PBT/PET side-by-side bicomponent fibers were produced and subjected to drawing from 1.6 to 4.0 times at 80 °C to induce crimping. Increasing draw ratios significantly enhanced fiber tenacity (from 0.64 to 3.91 cN/dtex) and reduced crimp radius (from 2.05 mm to 0.64 mm). A predictive crimp curvature model integrating Denton’s crimp theory and a four-element viscoelastic model was established, with corrected results achieving an R² of 0.9951. Additionally, four-lobed fibers showed better wettability, with a static contact angle 3.56° lower than that of circular fibers. This work provides theoretical guidance for high-performance self-crimping fiber design. Full article

Amidst environmental concerns regarding the use of petroleum-based materials, wood and wood-based products are among the key players in the pursuit of green construction practices. However, environmental degradation of these materials remains a concern during structural design, particularly for outdoor applications. Borrowed from anatomy to preserve human body parts, this study applies and assesses a technique called ‘plastination’ as a new means for moisture management of Western Red Cedar (WRC). Specifically, the proposed technique includes acetone dehydration of WRC, followed by SS-151 silicone vacuum-assisted impregnation and silicone curing. To evaluate the method’s effectiveness, Micro X-ray Computed Tomography (μCT), Fourier Transform Infrared (FTIR) Spectroscopy, Thermogravimetric Analysis (TGA), and static water contact angle measurements were employed. Tensile testing was also performed to quantify the treatment’s effect on WRC’s mechanical properties under moisture conditioning. μCT confirmed an impregnation depth of 21.5%, while FTIR and TGA results showed reduced moisture retention (3.6 wt%) in plastinated WRC due to the absence of hydroxyl groups. Mechanical testing revealed enhanced deformability in treated samples without compromising tensile strength. Upon moisture conditioning, plastinated WRC retained its tensile properties and showed 59% lower moisture absorption and 15% lower weight as compared to conditioned virgin samples. Full article

With the increase in contamination by microbial agents (bacteria, viruses, etc.) in the fields of agri-food, healthcare, and environment, it is necessary to detect and quantify these biological elements present in complex fluids in a short time with high selectivity, high sensitivity, and, if possible, moderate cost. Acoustic wave biosensors, based on immuno-detection, appear to meet a certain number of these criteria. In this context, we are developing a generic antibody-based biointerface that can detect a wide range of pathogenic bacterial agents using a specific bioreceptor. Based on the silane–oxide chemistry, the process is transferable to any kind of surface that can be either oxidized in surface or activated with O₂-plasma, for instance. For this proof of concept, we have chosen to develop our biointerface on titanium and lithium niobate surfaces. The development of the biointerface consists of grafting antibodies via a self-assembled monolayer (SAM) composed of an aminopropyltriethoxysilane (APTES) and a linker (phenylene diisothiocyanate, PDITC). Two functionalization routes were tested for grafting APTES: in anhydrous toluene followed by a heating step at 110 °C or in chloroform at room temperature. The results obtained on titanium show comparable grafting efficiency between these two routes, allowing us to consider the transposition of the route at room temperature on lithium niobate. The latest route was chosen for fragile materials that do not require the heating steps necessary when using toluene for grafting aminopropyltriethoxysilane. Different surface characterization techniques were used, such as IR spectroscopy (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), and contact angle (WCA), to verify the successful grafting of each layer. Biodetection experiments in static conditions were also carried out to demonstrate the specificity of pathogenic detection, testing an ideal medium with solely bacteria, with no other food sampling nutrients. This paper demonstrates the successful elaboration of a biointerface using APTES as the first anchoring layer, with chloroform as a mild solvent. The process is easily transferable to any kind of fragile surface. Moreover, following anti-L. monocytogenes antibodies, our biointerface shows a specificity of capture in static mode (at a concentration of 10⁷ CFU/mL for an incubation time of 4 h at 37 °C) of up to 98% compared to a species negative control (E. coli) and up to 85% in terms of strain specificity (L. innocua). Full article

In support of sustainable agricultural practices and soil conservation in black soil regions, the accurate modeling of soil–machine interactions is essential for optimizing tillage operations and minimizing environmental impacts. To achieve the precise calibration of interaction parameters between black soil and soil-engaging components, this paper proposes an innovative segmented calibration method to determine the discrete element parameters for interactions between black soil and agricultural machinery parts. The Hertz–Mindlin with Johnson–Kendall–Roberts (JKR) Cohesion contact model in the discrete element method (DEM) software was employed, using a two-stage calibration process. In the first stage, soil particle contact parameters were optimized by combining physical pile angle tests with multi-factor simulations guided by Design-Expert, resulting in the optimal parameter set (JKR surface energy 0.46 J/m², restitution coefficient 0.51, static friction coefficient 0.65, rolling friction coefficient 0.13). In the second stage, based on validated soil parameters, the soil–65Mn steel interaction parameters were precisely calibrated (JKR surface energy 0.29 J/m², restitution coefficient 0.55, static friction coefficient 0.64, rolling friction coefficient 0.07). Simulation results showed that the error between simulated and measured pile angles was less than 0.5%. Additionally, verification through rotary tillage operation tests comparing simulated and measured power consumption demonstrated that within the cutter roller speed range of 150–350 r·min⁻¹, the power error remained below 0.5 kW. Ground surface flatness was introduced as a supplementary validation indicator, and the differences between simulated and measured values were small, further confirming the accuracy of the DEM model in capturing soil–tool interaction and predicting tillage quality. This paper not only enhances the accuracy of DEM-based modeling in agricultural engineering but also contributes to the development of eco-efficient tillage tools, promoting sustainable land management and soil resource protection. Full article

The influence of minor components on leaching molecular iodine (I₂) through polypropylene (PP)-based packaging from a povidone iodine-based (PVP-I) formulation, simulating an ophthalmic application, was evaluated. I₂ is a cheap, broad-spectrum, and multi-target antiseptic. Nevertheless, it is volatile, and the prolonged storage of I₂-based formulations is demanding in plastic packaging because of transmission through the material. Therefore, we explored the possibility of moderating the loss of I₂ from an iodophor formulation by introducing small amounts of molecular iodine into the polymer material commonly used in eyedropper caps, i.e., PP. Thus, PP was blended via an extrusion process with a polymeric complex containing iodine (such as PVP-I) or with a second polymeric component able to complex the I₂ released from an iodophor solution. The aim of this work was to introduce I₂ into PP-based polymer matrices without using organic solvents and indirectly, i.e., through the addition of components that could generate molecular iodine or complex it in the solid phase, as I₂ is heat-sensitive. To increase the miscibility between PP and PVP-I, poly(N-vinylpyrrolidone) (PVP) or a vinyl pyrrolidone vinyl acetate copolymer 55/45 (Sokalan) were added as compatibilizers. The PP-based binary and ternary blends, in granular or sheet form, were characterized thermally (Differential Scanning Calorimetry, DSC, and Thermogravimetric analysis, TGA), mechanically (tensile tests), morphologically (scanning electron microscopy (SEM)), and chemically (attenuated total reflectance Fourier transform infrared (ATR-FTIR)). Additionally, the variation in wettability induced by the introduction of the hydrophilic minority components was determined by static contact angle measurements (static contact angle (SCA)), and tests were carried out to determine the barrier properties against oxygen (oxygen transmission rate (OTR)) and molecular iodine. The I₂ leaching of the different blends was compared with that of PP by monitoring the I₂ retention in a buffered PVP-I solution via UV-vis spectroscopy. Overall, the experimental data showed the capability of the minority components in the blends to increase thermal stability as well as act as a barrier to oxygen. Additionally, the PP blend with PVP-I induced a reduction in molecular iodine leaching in comparison with PP. Full article