Search Results (506)

Lightweightness and durability are key consumer demands for footwear. To address the issues of deformation and poor durability in foamed sole materials, this study integrates natural fibers into the formulation of foamed rubber. The effects of natural fiber incorporation on density, mechanical properties, creep behavior, anti-slip performance, and aging resistance were comprehensively analyzed. Additionally, the study explored the mechanisms underlying the improved performance of the modified rubber materials. The results revealed that natural fiber integration significantly enhanced the structural stability, strength, and aging resistance of natural rubber (NR). Among the fibers compared, collagen fibers (CF) proved to be the most effective modifier for foamed NR. The density, tensile strength, tear strength, and coefficient of friction of CF-modified foamed NR (CF-NR) were found to be 0.72 g/cm³, 10.1 MPa, 48.0 N/mm, and 1.105, respectively, meeting the standard requirements for sole materials. Furthermore, CF-NR demonstrated a recoverable deformation of 4.58% and a negligible irreversible deformation of 0.10%, indicating a successful balance between comfort and durability. This performance enhancement can be attributed to the supportive role of CF in the pore structure, along with its inherent flexibility and recoverability. This work presents a novel approach for the development of high-quality, lightweight footwear in the sole material industry. Full article

Exoskeletons transfer loads to the human body via physical human–exoskeleton interfaces (pHEI). However, the human–exoskeleton interaction remains poorly understood, and the mechanical properties of the pHEI are not well characterized. Therefore, we present a novel methodology to precisely characterize pHEI interaction stiffnesses under various loading conditions. Forces and torques were applied in three orthogonal axes to the upper arm pHEI of 21 subjects using an electromechanical apparatus. Interaction loads and displacements were measured, and stiffness data were derived as well as mathematically described using linear and non-linear regression models, yielding all the diagonal elements of the stiffness tensor. We find that the non-linear nature of pHEI stiffness is best described using exponential functions, though we also provide linear approximations for simplified modeling. We identify statistically significant differences between loading conditions and report median translational stiffnesses between 2.1 N/mm along and 4.5 N/mm perpendicular to the arm axis, as well as rotational stiffnesses of 0.2 N·m/° perpendicular to the arm, while rotations around the longitudinal axis are almost an order of magnitude smaller (0.03 N·m/°). The resulting stiffness models are suitable for use in digital human–exoskeleton models, potentially leading to more accurate estimations of biomechanical efficacy and discomfort of exoskeletons. Full article

Utilizing edible films/coatings promises to extend the shelf life of fruits by controlling various physiological parameters (e.g., respiration and transpiration rates), maintaining firmness, and delaying fruit senescence. The influence of composite-based edible coatings made from sodium or calcium caseinate: carboxymethyl chitosan (75:25) on the postharvest quality of fresh blueberries was assessed over a 28-day storage period, on the basis of weight loss and changes in pH, firmness, color, titratable acidity, soluble solids content, mold and yeast count, and respiration rate. The pH of the blueberries increased over the period of storage, with significant differences observed between uncoated and coated (e.g., pH was 3.89, 3.17, and 3.62 at the end of the storage time for uncoated, Ca 75-1% SO, and Na 75-1% SO, respectively. Desirable lower pH values at the end of storage were obtained with the calcium caseinate formulations. Over the duration of storage, other quality parameters (e.g., firmness) were better retained in coated fruits compared to the uncoated (control) one. At the last storage day, the firmness of the uncoated sample was 0.67 N·mm⁻¹ while the sodium and calcium caseinate was 0.63 and 0.81 N.mm⁻¹, respectively. Moreover, the microbial growth was reduced in coated fruits, indicating the effectiveness of coatings in preserving fruit quality. The mold /yeast count was 1.4 and 2.3 log CFU/g for CaCa 75-1% SO and NaCa 75-1% SO compared with uncoated with 4.2 log CFU/g. Adding soybean oil to the caseinate–carboxymethyl chitosan composite edible coating has the potential to positively influence retention of various quality parameters of blueberries, thereby extending their shelf life and maintaining overall quality. Further research could explore the optimization of coating formulations and application methods to enhance their effectiveness in preserving fruit quality during storage. Full article

Antimicrobial resistance in infected chronic wounds present significant risk of complications (e.g., amputations, fatalities). This research aimed to formulate honey-loaded hydrocolloid film comprising gelatin and HPMC, for potential treatment of infected chronic wounds. Honeys from different sources (Cameroonian and Manuka) were used as the bioactive ingredients and their functional characteristics evaluated and compared. The formulated solvent cast films were functionally characterized for tensile, mucoadhesion and moisture handling properties. The morphology and physical characteristics of the films were also analyzed using FTIR, X-ray diffraction and scanning electron microscopy. Antibacterial susceptibility testing was performed to study the inhibition of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus by honey components released from the films. The % elongation values (8.42–40.47%) increased, elastic modulus (30.74–0.62 Nmm) decreased, the stickiness (mucoadhesion) (0.9–1.9 N) increased, equilibrium water content (32.9–72.0%) and water vapor transmission rate (900–298 gm² day⁻¹) generally decreased, while zones of inhibition (2.4–6.5 mm) increased with increasing honey concentration for 1 and 5% w/v, respectively. The results generally showed similar performance for the different honeys and demonstrate the efficacy of honey-loaded hydrocolloid films as potential wound dressing against bacterial growth and potential treatment of infected chronic wounds. Full article

Pangasius (Pangasianodon hypophthalmus) minced muscle with 1 and 2% salt was treated with different high-pressure processing and thermal methods, including conventional heat-induced gels (HIGs), high-pressure processing (HPP) prior to cooking (PC), HPP prior to setting (PS), and setting prior to HPP (SP), to evaluate for their effects on the selected physicochemical properties. The results showed that the PC treatment produced gels with a significantly higher gel strength (496.72–501.26 N·mm), hardness (9.62–10.14 N), and water-holding capacity (87.79–89.74%) compared to the HIG treatment, which showed a gel strength of 391.24 N·mm, a hardness of 7.36 N, and a water-holding capacity of 77.98%. PC gels also exhibited the typical microstructure of pressure-induced gels, with a denser and homogeneous microstructure compared to the rough and loosely connected structure of HIGs. In contrast, SP treatment exhibited the poorest gel quality in all parameters, with gel strength ranging from 319.79 to 338.34 N·mm, hardness from 5.87 to 6.31 N, and WHC from 71.91 to 73.72%. Meanwhile, the PS treatment showed a comparable gel quality to HIGs. SDS-PAGE analysis revealed protein degradation and aggregation in HPP-treated samples, with a decrease in the intensity of myosin heavy chains and actin bands. Fourier-transform infrared spectroscopy (FTIR) analysis showed minor shifts in protein secondary structures, with the PC treatment showing a significant increase in α-helices (28.09 ± 0.51%) and a decrease in random coil content (6.69 ± 0.92%) compared to α-helices (23.61 ± 0.83) and random coil structures (9.47 ± 1.48) in HIGs (p < 0.05). Only the PC treatment resulted in a significant reduction in total plate count (TPC) (1.51–1.58 log CFU/g) compared to 2.33 ± 0.33 log CFU/g in the HIG treatment. These findings suggest that HPP should be applied prior to thermal treatments (cooking or setting) to achieve an improved gel quality in reduced-salt pangasius products. Full article

Both the pulp and the seeds of rosehip are important for human health. Rosehip seeds are rich in polyunsaturated fats, which support a healthy skin membrane and protect it from inflammatory factors. In order to be used, the seeds require initial processing, mainly by grinding. This paper first presents a brief review of the physicochemical properties and the content of bioactive compounds in rosehip (Rosa canina) and its seeds. Original research results on the compression behavior of rosehip seeds are presented below, together with the key values of the most important parameters derived from the analysis. For seeds with a thickness ranging from 1.80 to 3.55 mm, the compressive force at the onset of fracture was recorded to be between 94.4 and 156.0 N, while the force required for complete fracture ranged from 114.0 to 495.0 N (with about 12.5% of values considered outside a normal distribution). Additionally, for these forces, the deformation of the seeds ranged between 0.142 and 0.916 mm at the onset of fracture and between 0.248 and 1.878 mm at complete fracture. For these characteristics, the energy consumed ranged between 0.012 and 0.041 J at the onset of fracture and between 0.017 and 0.322 J at complete breaking. The elasticity of the seeds also ranged between 159.9 and 789.1 N/mm, considering the forces and deformations at the onset of fracture. The results of our study contribute to expanding the database on the mechanical characteristics of rosehip seeds, knowledge of which is essential for the initial processing operations used in the pharmaceutical industry aimed at oil extraction. Full article

Although linear overproduction and overconsumption have benefited businesses, they have created an unsustainable society. Converting wood waste into construction material can support the transition to a circular economy. The mechanical properties of beams constructed from wood waste were measured. Squares with 50, 60, and 70 mm side lengths were glued to create beams, to which the three-point test method was applied parallel to the fibres. The stiffness and moduli of elasticity and rupture were analysed with standard industrial statistical techniques. Specifically, a two-stage analysis was performed using the normal distribution and Shewhart control charts. Changes of 100 mm in width and height and 200 mm in length caused a change of 200–400 N/mm² in elasticity and 500–1300 MNmm² in stiffness. Modulus of rupture values were relatively comparable, as they were determined by the properties of oak wood, from which the beams were made. The observed differences in the tested mechanical parameters will be useful in the optimisation of furniture construction, with our research suggesting that it is possible to predict mechanical properties from the dimensions of the waste-wood pieces. Ultimately, this should help to design sustainable furniture that is aesthetic, functional, and safe. Full article

The present study investigated the efficacy of edible coatings formulated with gellan gum and lemon peel extract (LPE) in preserving the postharvest quality of cherry tomatoes (Solanum lycopersicum var. cerasiforme). Selected fruits exhibiting uniform ripeness and free from defects were sanitized and coated with solutions containing different HAG/LAG (high- and low-acyl gellan gum) ratios, incorporating 4.0% (w/v) LPE. Physicochemical and physiological parameters, including soluble solids content, weight loss, pH, titratable acidity, oxygen consumption, carbon dioxide and ethylene production, skin redness (a*/b* ratio), and decay incidence, were systematically assessed under storage conditions of 25 °C and 70% relative humidity. HAG-coated fruits showed the lowest weight loss (1.08%), higher soluble solids (7.11 °Brix), and greater firmness (3.11 N/mm²) compared to uncoated controls. Moreover, they exhibited reduced oxygen consumption (0.06 mg·kg⁻¹·h⁻¹), ethylene production (3.10 mg·kg⁻¹·h⁻¹), and decay rate (2%). Redness was better preserved, and decay rates were substantially (p < 0.05) reduced throughout the storage period. These findings highlight the potential of HAG-based edible coatings enriched with LPE as an innovative postharvest technology to extend shelf life, maintain quality attributes, and reduce postharvest losses in cherry tomatoes. Full article

During the machining of unidirectional carbon fiber-reinforced polymers (UD-CFRPs), their anisotropic characteristics and the complex cutting conditions often lead to defects such as delamination, burrs, and surface/subsurface damage. This study systematically investigates the effects of different fiber orientation angles (0°, 45°, 90°, and 135°) on cutting force, chip formation, stress distribution, and damage characteristics using a coupled macro–micro finite element model. The model successfully captures key microscopic failure mechanisms, such as fiber breakage, resin cracking, and fiber–matrix interface debonding, by integrating the anisotropic mechanical properties and heterogeneous microstructure of UD-CFRPs, thereby more realistically replicating the actual machining process. The cutting speed is kept constant at 480 mm/s. Experimental validation using T700S/J-133 laminates (with a 70% fiber volume fraction) shows that, on a macro scale, the cutting force varies non-monotonically with the fiber orientation angle, following the order of 0° < 45° < 135° < 90°. The experimental values are 24.8 N/mm < 35.8 N/mm < 36.4 N/mm < 44.1 N/mm, and the simulation values are 22.9 N/mm < 33.2 N/mm < 32.7 N/mm < 42.6 N/mm. The maximum values occur at 90° (44.1 N/mm, 42.6 N/mm), while the minimum values occur at 0° (24.8 N/mm, 22.9 N/mm). The chip morphology significantly changes with fiber orientation: 0° produces strip-shaped chips, 45° forms block-shaped chips, 90° results in particle-shaped chips, and 135° produces fragmented chips. On a micro scale, the microscopic morphology of the chips and the surface damage characteristics also exhibit gradient variations consistent with the experimental results. The developed model demonstrates high accuracy in predicting damage mechanisms and material removal behavior, providing a theoretical basis for optimizing CFRP machining parameters. Full article

This paper aimed to evaluate the effect of cross-linking temperature on the rheological, mechanical, and thermal properties of CR/BR compositions cross-linked with zinc oxide, iron(III) oxide, or copper(II) oxide. Properties of CR/BR compounds were studied at four temperatures: 140, 160, 180, and 200 °C. The lowest activation energy of vulcanization was shown by blends cross-linked with ZnO, and the highest activation energy of vulcanization was shown by samples with Fe₂O₃. Blends cured with ZnO or Fe₂O₃ showed higher cross-linking activity than CuO. Higher temperatures enhanced the degree of cross-linking in the CR/BR composite cured with ZnO or CuO but slightly reduced it for the CR/BR/Fe₂O₃ vulcanizates. The highest tensile strength was observed for the CR/BR/Fe₂O₃ product. However, compositions cured with ZnO exhibited the best aging resistance. The CR/BR compounds cured with ZnO at high temperatures had the highest tear strength (16.8 N/mm), while samples containing CuO as a curing agent showed declining tear strength with temperature. DSC confirmed a single glass transition (~36 °C), indicating good elastomers dispersion. Infrared and SEM analyses confirmed effective cross-linking and blend compatibility. Full article

The study investigates the problem of modeling cutting-force components through response surface methodology and reports the results of an investigation into the impact of machining parameters on the cutting mechanics of polymer–matrix composites. The novelty of this study is the modeling of cutting forces and the determination of mathematical models of these forces. The models describe the values of forces as a function of the milling parameters. In addition, the cutting resistance of the composites was determined. The influence of the material and rake angle of individual tools on the cutting force components was also determined. Measurements of the main (tangential) cutting force showed that, using large rake angles for uncoated carbide tools, one could obtain maximum force values that were similar to those obtained with polycrystalline diamond tools with a small rake angle. The results of the analysis of the tangential component of cutting resistance showed that, regardless of the rake angle, the values range from 140 N to 180 N. An analysis of the feed component of cutting resistance showed that the maximum values of this force ranged from 46 N to 133 N. The results showed that the highest values of the feed component of cutting resistance occurred during the machining of polymer composites with carbon fibers and that they were most affected by feed per tooth. It was also shown that the force models determined during milling with diamond insert tools had the highest coefficient of determination in the range of 0.90–0.99. The cutting resistance analysis showed that the values tested are in the range of 3.8 N/mm² to 15.5 N/mm². Full article

Acacia hybrid is an important plantation species in Malaysia, but its use in structural applications is still limited due to the lack of comprehensive data on its engineering properties. This study evaluated the physical and mechanical properties of laminated or glulam Acacia hybrid timber in an air-dried condition for three age group combinations (7//10, 10//13, and 7//13 years old) to determine the optimal combination for structural applications. The results showed that the 10//13-year-old combination had the best mechanical performance, along with the highest basis density (0.7099 g/cm³), highest modulus of elasticity (MOE) (16,335.6 N/mm²), and highest parallel compressive strength (56.998 N/mm²), while the 7//10-year-old combination showed the highest moisture content (14.94%) and highest perpendicular compressive strength (8.9256 N/mm²). This study demonstrated that the combination of juvenile wood (7 years old) with mature wood (10 or 13 years old) increased strength by up to 43.06%, thus optimising the potential of Acacia hybrid in the construction industry. All combinations meet SG5 standards, with the 10//13-year-old combination recommended as the best choice for high-performance applications of glulam products. Full article

This study proposes a dual-statistical and gradient-based framework to evaluate the machinability of five engineering alloys under CNC turning. Cutting force and surface deformation were measured across five machining zones. Finite difference-based gradients revealed spatial variations in material response. Stainless Steel 304 showed the highest cutting force (328 N), while Aluminum 6061 had the highest deformation (0.0164 mm). Carbon Steel 1020 exhibited the highest force-to-deformation efficiency (>97,000 N/mm). Arithmetic and harmonic means highlighted statistical sensitivities, while principal component analysis (PCA) identified clustering among materials and reduced dimensionality. A composite machinability score, integrating stiffness variation, efficiency gradients, and multivariate features, ranked Aluminum 6061 highest, followed by Brass C26000 and Bronze C51000. This methodology enables interpretable benchmarking and informed material selection in precision manufacturing. Full article

Lightweight, layered wood-based panels are gaining attention due to favorable mechanical and physical properties. This study examined numerical modeling as a method to predict the strength of innovative three-layer sandwich panels with thermoplastic cores containing wood particles as the filler. Two core geometries (F and S) and two material formulations (60% HDPE + 40% sawdust, and 40% HDPE + 60% sawdust) were tested. The panels were produced without additional adhesives; bonding with high-density fiberboard (HDF) facings was achieved through the thermoplastic properties of the core. Mechanical properties such as bending strength (MOR), modulus of elasticity (MOE), and compressive strength perpendicular to the surface were measured. Results showed that both core geometry and material composition significantly influenced structural performance. Panels with the F profile showed better bending strength and stiffness (MOR—13.2 N/mm², MOE—2017 N/mm²), while the S profile had higher compressive strength (0.62 N/mm²). Numerical simulations using SolidWorks Simulation confirmed the experimental data, with stress and displacement distributions matching laboratory results. These findings demonstrate the potential of thermoplastically formed cores for creating lightweight, recyclable wood-based composites with tailored mechanical properties. Full article

This study evaluated the effects of different clear aligner (CA) designs on forces and moments during maxillary second molar distalization. Four designs were tested: attachment only (group 1), neither attachment nor enhanced structure (group 2), a combination of attachment and enhanced structure (group 3), and enhanced structure only (group 4). CAs were fabricated from thermoformed polyethylene terephthalate glycol with 30 CAs per group. Forces and moments were measured using a multi-axis transducer as the molars were distally displaced by 0.25 mm. All groups experienced buccodistal and intrusive forces. Group 3 showed the highest distalizing force (Fy = 2.51 ± 0.37 N) and intrusive force (Fz = −2.04 ± 0.48 N) and also the largest rotational moment (Mz = 3.89 ± 0.71 Nmm). Groups 3 and 4 (with enhanced structures) demonstrated significant intrusive forces (p < 0.05). Most groups exhibited mesiodistal angulation, lingual inclination, and distal rotational moments. Group 2 had the lowest moment-to-force ratio (Mx/Fy = 3.27 ± 0.44 mm), indicating inefficient bodily movement. Group 3 demonstrated significantly greater moments across all axes compared to other groups. The results indicate that designs incorporating enhanced structures with attachments increase CA stiffness and applied forces/moments, enhancing distalization efficiency while minimizing vertical side effects. This suggests that, clinically, reinforced CAs can serve as a simple yet effective modification to existing protocols in Class II orthodontic cases, enabling more efficient molar distalization without requiring complete appliance redesign or additional fabrication and allowing easy adaptation to individual treatment needs. Full article