Search Results (3,298)

Some common conductive polymers are polyfuran, polyacetylene, polythiophene, and poly-pyrrole. Since their discovery, many researchers have been exploring and evaluating their conductive and electronic properties. Various applications have been developed for conductive materials. Their biocompatibility offers a new alternative for studying and solving complex problems, such as cellular activity, or, more recently, for use as neural implants and as an alternative to spinal cord regenerative tissue. This is particularly true for the use of poly pyrrole. The main obstacle lies in estimating some of the mechanical properties, such as Young’s or shear modulus values for poly pyrrole, since these vary depending on the type of synthesis used. This article outlines a composite methodology for characterizing the elastic modulus according to ASTM D882 and the shear modulus according to E143 standards. It is specifically designed and applied for 3D composite samples involving PLA and PPy, where the PPy was processed by plasma oxidation. As a result, an increase of 360.11 MPa in the modulus of elasticity is observed on samples coated with poly pyrrole. The results are evaluated through a numerical test using COMSOL Multiphysics software 6.2 version, finding a similar behavior in the elastic zone, as indicated by the stress–strain diagram. The statistical analysis yields consistent data for tensile and shear results, with low to moderate variability. Full article

Okara, a fiber-rich soybean byproduct, can improve the sustainability of plant-based meats but may compromise texture when used at high levels. This study investigated the effects of okara flour (0–40%) on the structure–function relationships of high-moisture meat analogues (HMMA) formulated with soy protein isolate, wheat gluten, and corn starch. Analyses included composition, macrostructure, instrumental texture (cutting tests and TPA, evaluated by PCA), SDS-PAGE, and pasting behavior under both pressurized and atmospheric conditions. Increasing okara decreased protein density but increased fiber and fat, resulting in nutritional trade-offs. Fibrous anisotropy was preserved up to 20% okara but declined at higher levels, producing dense, isotropic matrices. Texture analyses revealed reduced firmness, cohesiveness, and elasticity, consistent with SDS-PAGE evidence of diminished 7S and 11S subunits. Rheological tests indicated suppressed starch swelling yet greater viscosity stability under pressure. Overall, moderate okara incorporation increased dietary fiber without fully compromising texture, whereas higher levels disrupted protein alignment and gel functionality. Full article

During deep coalbed methane (CBM) drilling, wellbore stability is significantly influenced by the interaction between drilling fluid and coal rock. However, quantitative data on mechanical degradation under long-term high-temperature and high-pressure conditions are lacking. This study subjected coal cores to immersion in field-formula drilling fluid at 60 °C and 10.5 MPa for 0–30 days, followed by uniaxial and triaxial compression tests under confining pressures of 0/5/10/20 MPa. The fracture evolution was tracked using micro-indentation (µ-indentation), nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM), establishing a relationship between water absorption and strength. The results indicate a sharp decline in mechanical parameters within the first 5 days, after which they stabilized. Uniaxial compressive strength decreased from 36.85 MPa to 22.0 MPa (−40%), elastic modulus from 1.93 GPa to 1.07 GPa (−44%), cohesion from 14.5 MPa to 5.9 MPa (−59%), and internal friction angle from 24.9° to 19.8° (−20%). Even under 20 MPa confining pressure after 30 days, the strength loss reached 43%. Water absorption increased from 6.1% to 7.9%, showing a linear negative correlation with strength, with the slope increasing from −171 MPa/% (no confining pressure) to −808 MPa/% (20 MPa confining pressure). The matrix elastic modulus remained stable at 3.5–3.9 GPa, and mineral composition remained unchanged, confirming that the degradation was due to hydraulic wedging and lubrication of fractures rather than matrix damage. These quantitative thresholds provide direct evidence for predicting wellbore stability in deep CBM drilling. Full article

Composite pressure vessels have attracted significant attention in recent years owing to their lightweight characteristics and superior mechanical performance. However, analyzing composite layers remains challenging due to complex filament-winding (FW) pattern structures and the associated high computational costs. This study introduces a homogenization method to achieve cross-scale modeling of carbon fiber-reinforced plastic (CFRP) layers, accounting for both lay-up sequence and in-plane FW diamond-shaped form. The stacking sequence in an FW Type IV composite pressure vessel is numerically investigated through ply modeling and cross-scale homogenization. The composite tank structure, featuring a polyamide PA66 liner, is designed for a working pressure of 70 MPa and comprises 12 helical winding layers and 17 hoop winding layers. An FW cross-undulation representative volume element (RVE) is developed based on actual in-plane mesostructures, suggesting an equivalent laminate RVE effective elastic modulus. Furthermore, six different lay-up sequences are numerically compared using ply models and fully and partially homogenized models. The structural displacements in both radial and axial directions are validated across all modeling approaches. The partial homogenization method successfully captures the detailed fiber-direction stress distribution in the innermost two hoop or helical layers. By applying the Hashin tensile failure criterion, the burst pressure of the composite tank is evaluated, revealing 7.56% deviation between the partial homogenization model and the ply model. Fatigue life analysis of the Type IV composite pressure vessel is conducted using ABAQUS^® coupled with FE-SAFE, incorporating an S-N curve for polyamide PA66. The results indicate that the fatigue cycles of the liner exhibit only 0.28% variation across different stacking sequences, demonstrating that homogenization has a negligible impact on liner lifecycle predictions. The proposed cross-scale modeling framework offers an effective approach for multiscale simulation of FW composite pressure vessels, balancing computational efficiency with accuracy. Full article

A non-destructive method for determining the properties of laminated composite materials made of twill-weave glass fibre fabric is considered. To determine the elastic characteristics of the composite monolayer, a combined numerical–experimental method is used. The method combines the results of experimental tests and numerical modelling methods using optimization techniques. Firstly, the method for determining the properties is tested in a virtual experiment to determine the influence of the elastic characteristics of the material that do not affect the frequency response. The adequacy of the approximation equations and the influence of elastic constants on frequency response are evaluated using Analysis of Variance (ANOVA). Using the results obtained, the properties of the elastic characteristics of layered composite plates made of twill-weave glass fibre fabric using vacuum infusion are determined. To compare the properties obtained from the dynamic calculation, a series of static measurements of tensile samples were carried out. The results showed that the elastic modulus from the static test and the flexural test do not coincide by 4% and 23%, respectively. The technique demonstrates high accuracy and applicability for the non-destructive determination of dynamic material properties in engineering practice. Full article

The growing demand for dermocosmetics with ingredients of natural origin reflects the pivotal role of cutaneous health and appearance in consumer self-esteem. Under this context, clays have attracted attention for their potential applications in dermatological care. Our research work aimed to increase knowledge on the short-term impact of cosmetic formulations containing a blend of red, green, and black clays, assessing their effects on sebum regulation and in cutaneous biomechanical behavior (firmness/elasticity). Unlike daily skincare products, clay masks are used infrequently and for short durations; thus, an in vivo assessment was conducted after a 2-h application to reflect typical consumer use. The mineralogical and physicochemical properties of the different clays were characterized. Mineralogical analysis revealed distinct compositions among the clays: black clay exhibited a simpler mineral profile, lower density, and smaller particle size; green clay contained expandable smectite and was the densest; and red clay displayed the largest average particle size and highest iron content. Thermal analysis identified two major transitions: dehydration and kaolinite dehydroxylation. In vivo studies conducted in participants showed a significant reduction in skin oiliness across all clay-based formulations compared to baseline, control, and placebo following a 2-h application, and the rebound sebum production was dependent on clay concentration. Cutometry measurements did not reveal statistically significant improvements in skin firmness or elasticity compared to the control and placebo. The findings suggested that while clay-based formulations effectively reduced skin oiliness in the short term, their impact on sebum regulation and on skin biomechanical properties was limited after such a short product application period. Additional studies are warranted to elucidate the distinct effects of each clay, assess their behavior in different formulation bases, and evaluate their efficacy after repeated use. Full article

This study investigates the torsion characteristics of injection-molded flexural hinges manufactured from common polymers and plastic-based composites. The compliant mechanism provides a nearly constant torque over a specific rotational period. The flexural hinges are created via the injection molding technique, which has the advantage of mass production and low price. The injection plastics are pure polypropylene (PP), acrylonitrile butadiene styrene (ABS), and polyamide 6 (PA6), and the injection composites are PA6 combined with glass fibers. The torsional moment of the ABS flexural hinge ranges from −0.2 to 0.94 N∙m. The torsional moment of the PP polymer typically ranges from −0.6 to 0.8 N∙m. The torsional moment of the PA6 polymer ranges from −0.2 to 1.0 N∙m. Interestingly, the torsional moment diagram for this polymer is comparable to that of ABS, with a stable pattern in both positive and negative ranges. Furthermore, in other words, the PP flexural range is greater than the ABS range. Both ABS and PA6 flexural hinges have a higher level of stability compared to the PP one due to the higher elastic modulus and higher strength of these polymers than the PP polymer. The PP flexural hinge has the lowest negative torsional moment (−0.6 N∙m) compared to ABS and PA hinges. PA6 flexural hinges also have the most stable torsional moment compared to pure polymer varieties. Adding 5% to 10% fiberglass (FG) significantly improves the torsional moment of composite flexural hinges. More flexural hinges from different polymer types should be investigated. Further research should conduct some statistical analysis to clarify the variations between the torques for the various materials. The findings improve our understanding of plastic flexure hinges and expand their applicability. Full article

This study investigates the structural optimization of lightweight three-layer panels made from industrial hemp shives (core) and hemp fibers (faces) as a sustainable alternative to wood-based materials in furniture manufacturing. Panels with target densities of 400–600 kg·m⁻³ and face-layer contents of 30%–50%were produced and tested to European standards. The optimal configuration—600 kg·m⁻³ with ~37%–41% face layers—achieved a modulus of elasticity up to 3750 N·mm⁻² and a bending strength (MOR) up to 21.57 N·mm⁻². Across the design space, water absorption ranged from ~83% to 162%, and the minimum thickness swelling was ~29%, indicating that while the mechanical properties meet the requirements for P2 particleboards (EN 312) and in some cases approach MDF benchmarks for dry use, thickness swelling remains above the EN 622-5 limit (12%) and thus precludes MDF classification. These findings demonstrate the technical feasibility of hemp shive–fiber panels and underscore the need to balance density and face-layer ratio to avoid loss of core densification at excessive face contents. From a sustainability perspective, the use of rapidly renewable hemp and agricultural residues highlights the potential of these composites to support resource-efficient, low-carbon furniture production, while future work should target improved water resistance through binder and process modifications. Full article

In this study, the nonlinear forced vibration response of fiber-reinforced laminated composite beams coated with functionally graded materials (FGMs) is investigated under the combined action of aero-thermoelastic loads and a concentrated harmonic excitation. The mathematical formulation is established using the Euler–Bernoulli beam theory, where von Kármán geometric nonlinearities are taken into account, along with the modified third-order piston theory to represent aerodynamic effects. By neglecting axial inertia, the resulting set of nonlinear governing equations is simplified into a single equation. This equation is discretized through the Galerkin procedure, yielding a nonlinear ordinary differential equation. An analytical solution is, then, obtained by applying the method of multiple time scales (MTS). Furthermore, a comprehensive parametric analysis is carried out to evaluate how factors such as the power-law index, stacking sequence, temperature field, load amplitude and position, free-stream velocity, and Mach number influence both the lateral dynamic deflection and the frequency response characteristics (FRCs) of the beams, offering useful guidelines for structural design optimization. Full article

Gelatin is a collagen-derived biopolymer widely used in food, pharmaceutical and biomedical applications due to its biocompatibility and gelling ability. However, gelatin hydrogels suffer from unstable mechanical strength, limited thermal resistance and susceptibility to microbial contamination. The main aim of the present study is to investigate the influence of gelatin cryostructuring followed by photo-induced menadione sodium bisulfite (MSB) chemical crosslinking on the structural and functional characteristics of mammalian and fish gelatin hydrogels. The integration of scanning electron microscopy, dielectric spectroscopy and rheological experiments provides a comprehensive view of the of molecular, morphological and mechanical properties of gelatin hydrogels under photo-induced chemical crosslinking. The SEM results revealed that crosslinked hydrogels are characterized by enlarged pores compared to non-crosslinked systems. For mammalian gelatin, multiple pores with thin partitions are formed, giving a dense and stable polymer network. For fish gelatin, large oval pores with thickened partitions are formed, preserving a less stable ordered architecture. Rheological data show strong reinforcement of the elastic and thermal stability of mammalian gelatin. The crosslinked mammalian system maintains the gel state at higher temperatures. Fish gelatin exhibits reduced elasticity retention even after crosslinking because of a different amino acid composition. Dielectric results show that crosslinking increases the portion of bound water in hydrogels considerably, but for fish gelatin, bound water is more mobile, which may explain weaker mechanical properties. Full article

Given that the stock of coal gangue is increasing annually, and especially considering the problem of resource utilization after the spontaneous combustion of coal gangue accumulations with large thickness, the post-spontaneous combustion of coal gangue (SC coal gangue) from Yangquan, Shanxi, was selected as a research object. After crushing and screening, SC coal gangue was used as a coarse and fine aggregate, and through concrete mix design and a trial mix of concrete and mix ratio adjustment, concrete of strength grade C20 was obtained. Through experiments, the strength, elastic modulus, frost resistance, carbonation depth and other performance indicators of the concrete were measured. Using the SC coal gangue concrete, a 20 mm thick SC coal gangue panel was designed and manufactured. Through experimental tests, the bearing capacity, hanging force, impact resistance, impermeability and other properties of the board met the requirements of the relevant standards for building wallboard. For the SC coal gangue panel composite rock wool, its heat transfer coefficient decreased by 34.0%, air sound insulation was $\ge 45 \mathrm{d}\mathrm{B}$, and the self-weight of the external wallboard was reduced by 37.5%, so the related performance was better than the requirements of the current standard. The research results have been successfully applied to an office building project in Shanxi, China. Using SC coal gangue to make the external wallboard of the building, the reduction and recycling of solid waste are realized. In addition, the production of wall panels has been industrialized, thereby improving the construction efficiency. Full article

This study examines the influence of steel fiber reinforcement on the mechanical properties of geopolymer concrete incorporating different slag to fly ash binder ratios (75:25, 50:50, and 25:75). Three fiber contents (0%, 1%, and 2%) by volume were used to assess their impact on compressive strength, flexural strength, initial stiffness, and toughness. Compressive tests were conducted at 1, 7, and 28 days, while flexural behavior was evaluated through a four-point bending test at 28 days. The results showed that geopolymer concrete with 75% slag and 25% fly ash experienced the highest compressive strength and modulus of elasticity, regardless of the steel fiber content. The addition of 1% and 2% steel fiber content enhanced the compressive strength by 17.49% and 28.8%, respectively, compared to the control sample. The binder composition of geopolymer concrete plays a crucial role in determining its compressive strength. Reducing the slag content from 75% to 50% and then to 25% resulted in a 15.1% and 33% decrease in compressive strength, respectively. The load–displacement curves of the 2% fiber-reinforced beams display strain-hardening behavior. On the other hand, after the initial crack, a constant increase in load causes the specimen to experience progressive strain until it reaches its maximum load capacity. When the peak load is attained, the curve gradually drops due to a loss in load-carrying capacity known as post-peak softening. This behavior is attributed to steel’s ductility and is evident in specimens 75S25FA2 and 50S50FA2. Concrete with 75% slag and 25% fly ash demonstrated the highest peak load but the lowest ultimate displacement, indicating high strength but brittle behavior. In contrast, concrete with 75% fly ash and 25% slag showed the lowest peak load but the highest displacement. Across all binder ratios, the addition of steel fibers enhanced the flexural strength, initial stiffness, and toughness. This is attributed to the bridging action of steel fibers in concrete. Additionally, steel fiber-reinforced beams exhibited a ductile failure mode, characterized by multiple fine cracks throughout the midspan, whereas the control beams displayed a single vertical crack in the midspan, indicating a brittle failure mode. Full article

In this work, general purpose rubber composites were created based on a mixture of non-polar cis-1,4-isoprene rubber and cis-1,4-divinyl rubber as components. The main filler used was carbon black, while various graphite-like materials (graphite oxide, reduced graphite oxide, expanded graphite, and graphite nanoplatelets) served as additives. It was determined that the addition of these graphite-like materials resulted in a reduction in Mooney viscosity, with the introduction of graphene nanoplatelets having the most significant effect, contributing to a viscosity decrease of 8.5%. The relaxation rate increased, positively impacting elastic recovery and consequently reducing shrinkage. The introduction of graphite oxide, graphite nanoplatelets, and expanded graphite also increased the time to the onset of the vulcanization reaction; moreover, these additives lengthened the time needed to reach the optimum level of vulcanization. The addition of various graphite-like materials significantly affected the elongation at break, with the highest increase attributable to the addition of expanded graphite and reduced graphite oxide. It was found that the conditional tensile strength of these additives had little effect. Upon assessing the elastic-strength properties after aging, it was found that the inclusion of graphite-like materials reduced the elongation at break. Full article

Food waste from fish processing contributes significantly to environmental pollution, and fish skin is often discarded despite being a rich collagen source. This study evaluated the efficacy and consumer satisfaction of a ready-to-drink collagen supplement made from hydrolyzed collagen derived from seabass skin. The compositional analysis of this study revealed α-amino groups, hydroxyproline, and amino acids essential for skin elasticity, hydration, and tissue repair. A 30-day clinical trial was conducted in 36 Thai volunteers who were aged between 20 to 70 years, and their skin condition was assessed using a facial skin analyzer and a moisture analyzer on days 0, 15, and 30. Participants also completed self-perception and sensory satisfaction questionnaires. The results showed improved skin moisture, reduced pore size, and smoother skin texture. Participants reported high satisfaction, especially regarding increased moisture and skin smoothness. Sensory score evaluation showed favorable scores for color and taste; however, odor was the least preferred attribute with the lowest score. Notably, no adverse effects were reported throughout this study. The findings suggest that fish skin-derived collagen supplements can enhance skin appearance while offering a sustainable approach that converts fish by-products into functional skincare solutions aligned with global sustainability goals. Full article

Background: Osteoarthritis (OA) is a major global health issue, increasing with aging and obesity. Current therapies mainly address symptoms without modifying disease progression. Platelet-rich growth factor (PRGF) therapy has potential regenerative effects through high cytokines and growth factors, but the outcomes of these therapies remain heterogeneous. This study explores the relationship between patient nutritional status, PRGF characteristics, and clinical outcomes in knee OA treatment. Methods: Baseline anthropometric, metabolic, and nutritional assessments of 41 patients with knee OA who underwent PRGF treatment were conducted. Blood samples were analyzed for metabolic and inflammatory markers. PRGF composition was assessed by protein content and extracellular vesicle (EV) markers. KOOS and VAS pain scores were collected at 2, 6, and 12 months. Responders improved KOOS by ≥10 points. An elastic-net regularized logistic model allowed the identification of the predictors of treatment response. Results: KOOS and VAS scores improved significantly at all follow-ups. At 2 months, the PRGF of responder patients showed higher PRGF G-CSF levels; at 12 months, increased CD49e and HLA-ABC expression. Higher BMI correlated with increased IL-6, IL-1ra, and resistin in PRGF samples. Hypercholesterolemic patients displayed altered EV profiles, with elevated levels of CD8 but reduced CD49e, HLA-ABC, CD42a, and CD31. Multivariate analysis identified BMI, biceps fold, fat percentage, red blood cell, platelet, and neutrophil counts as predictors of early response. Conclusions: Metabolic and immunological factors influence PRGF composition and clinical efficacy in knee OA. Baseline body composition and hematological parameters as key predictors of response, highlighting the potential of personalized PRGF therapy. Full article