Search Results (163)

The brain’s extracellular matrix (ECM) serves as a dynamic and instructive regulator of glioma progression. The ECM provides structural support while integrating pharmacological and mechanical signals that influence glioma initiation, progression, and treatment resistance. Deviant ECM remodeling fosters tumor heterogeneity, invasion, and immune evasion by altering stiffness, composition, and cellular matrix signaling. We proposed that ECM remodeling in gliomas not only facilitates tumor growth and heterogeneity but also establishes advantageous biophysical and metabolic conditions that foster treatment resistance and recurrence. Our objective is to analyze current findings regarding the structural, biochemical, and mechanical roles of the brain ECM in glioma growth, emphasizing its contribution to tumor heterogeneity, mechanotransduction, immunological modulation, and its potential as a therapeutic target. Method: A comprehensive literature review was conducted using scientific databases including PubMed, Web of Science, and Scopus. Peer-reviewed literature published between 2000 and 2025 was selected for its relevance to ECM composition, stiffness, remodeling enzymes, extracellular vesicles, and mechanobiological processes in gliomas. Results: Recent investigations demonstrate that glioma cells actively alter the ECM by secreting collagens, laminins, and metalloproteinases, establishing a feedback loop that facilitates invasion and resistance. Discussion: Mechanical variables, such as ECM stiffness and solid stress, influence glioma growth, metabolism, and immune exclusion. Moreover, extracellular vesicles facilitate significant extracellular matrix remodeling and improve communication between tumors and stromal cells. The disruption of ependymal and subventricular extracellular matrix niches enhances invasion and cerebrospinal fluid-mediated signaling. The remodeling of the ECM influences glioma growth through interconnected biochemical, mechanical, and immunological mechanisms. Examining ECM stiffness, crosslinking enzymes, and vesicle-mediated signaling represents a potential therapeutic approach. Integrative methodologies that combine mechanobiology, imaging, and multiomics analysis could uncover ECM-related vulnerabilities to improve glioma treatment. Full article

To investigate the flexural behavior of steel–concrete composite bridge decks with stud–perfobond leist (PBL) shear connectors, two specimens were designed with the stud spacing as the main variable, and static bending tests were conducted. Additionally, refined finite element models were constructed for evaluating the influence of shear connector types, concrete strength, stud diameter, stud height, and PBL hole diameter on the performance and flexural capacity of the structure. The results show that, under bending loads, the failure of the composite bridge deck is mainly concrete crushing and steel plate yielding. When the spacing of the stud decreases, both the flexural behavior of the composite bridge decks and the shear resistance at the steel–concrete interface are enhanced. The steel–concrete composite bridge decks with stud–PBL shear connectors showed higher overall flexural stiffness and flexural capacity than the steel–concrete composite bridge decks with single-type shear connectors. Concrete strength had a pronounced influence on the flexural capacity of the deck system, while the effects of stud diameter and height were minor. As the PBL hole diameter increased, the flexural capacity of the specimens exhibited a decreasing tendency. Full article

In this study, an I-optimal design was used to select an optimal muña essential oil nanoemulsion (MEO-NE) for application in active starch-based films. Four independent variables were used to optimize the process: emulsifier concentration (X₁) (% w/w), sonication time (X₂) (min), essential oil concentration (X₃) (% w/w), and emulsifier type (X₄) (Tween 80 or sapote gum). Results revealed that MEO-NE containing 5.24% of MEO, 6% Tween^® 80, and 9 min of ultrasound treatment exhibited a small droplet size (Y₁) (48.6 nm), moderate ζ-potential (Y₂) (−15 mV), and DPPH inhibition (Y₃) (95.6%). Starch-based films were incorporated with optimized MEO-NE at 5% (F₁) and 10% (F₂) and compared with control films (F₀). F₁ and F₂ exhibited lower moisture content, water solubility, and water vapor permeability than F₀; however, their contact angles were higher. The addition of MEO-NE into the polymeric matrix increased the stiffness of F₁ and F₂; however, the elongation at yield was slightly lower than that of F₀, resulting in less stretchable composite films. All films were disintegrated by more than 90% after 5 days of burial under composting conditions. The incorporation of MEO-NE into composite films significantly enhanced their properties, suggesting their potential use as eco-friendly packaging. Full article

The study analysed epoxy–glass laminates containing carbonisate produced during medium-density fibreboard (MDF) waste pyrolysis were evaluated with respect to their hardness and their ability to withstand impact loads. All composite samples were prepared manually using a hand-laying method, using two resin–reinforcement ratios (60/40 and 65/35) and carbonisate additives in amounts of 5% and 7.5% by weight (with particle sizes < 500 µm). The mechanical properties were assessed on the basis of hardness tests using the Barcol method and impact tests using the Charpy method. To analyse the results, a normality assessment (Shapiro–Wilk) was performed, followed by a non-parametric analysis of variance based on ranks (Kruskal–Wallis). It was found that an increase in carbonisate content increases the surface hardness of composites while reducing their impact resistance, which confirms the existence of a typical trade-off between stiffness and energy absorption capacity. The most favourable mechanical properties were obtained for a composite containing 7.5% carbonisate material and a resin–reinforcement ratio of 60/40, which was characterised by the highest hardness (35.19 HBa), a moderate impact strength (43.56 kJ/m²) and the lowest variability of results. The statistical analysis confirmed significant differences between the tested samples and a quantitative relationship between hardness and impact strength. The results of the study indicate that carbonisate (MDF) using waste material as a filler provides a sustainable means of improving the stiffness and consistency of epoxy–glass composites, with only a negligible effect on their ability to resist fracture. Full article

Background and Objectives: Alopecia areata (AA) is an autoimmune disorder characterized by non-scarring hair loss and has been associated with systemic immune-inflammatory activity and potential cardiometabolic risk. This study aimed to evaluate cardiovascular risk markers—including ECG parameters, arterial stiffness indices, anthropometric measurements, and body composition—in patients with AA according to disease severity and duration, and to compare these findings with healthy controls. Materials and Methods: This case–control study included 50 AA patients (32 men, 18 women; mean age: 28.98 ± 9.81 years) and 50 healthy controls (30 men, 20 women; mean age: 28.00 ± 7.86 years). All participants underwent anthropometric and electrocardiographic evaluations. Body composition was assessed, and arterial stiffness was measured. Subgroup analyses were performed according to SALT score (mild vs. moderate-to-severe) and disease duration (≥10 years vs. <10 years). Results: Heart rate was lower in AA patients compared with controls (mean difference −5.14 bpm; 95% CI −10.267 to −0.013). No significant differences were found between the groups regarding anthropometric variables, body composition, or arterial stiffness indices. Among AA patients, those with moderate-to-severe disease had significantly lower body fat mass (mean difference 4.95 kg; 95% CI 0.26 to 9.644) and lower visceral fat rating (mean difference 2.428 units; 95% CI 0.800 to 4.056) compared with mild AA. Conclusions: AA patients demonstrated lower heart rate and disease-severity-related alterations in body composition, although the clinical significance of these findings remains uncertain. Larger longitudinal studies are needed to clarify whether these subclinical differences translate into meaningful cardiovascular risk over time. Full article

The construction sector faces growing pressure to reduce its environmental impact, particularly in regions with limited access to conventional materials and urgent housing needs. Bamboo, a fast-growing and renewable resource with favorable mechanical properties, offers a sustainable alternative for structural applications. This study aims to enhance the efficiency of bamboo–concrete composites by investigating shear connection methods for composite floor systems. Different connection configurations were examined: (i) notch-type, (ii) dowel-type, and (iii) combined systems. Symmetric push-out tests were conducted to evaluate the load transfer mechanisms between bamboo logs and concrete layers. The mechanical behavior of each configuration was characterized through load–slip responses, failure modes, stiffness, strength, and deformation capacity. The results show that notch-type connections with longer grooves provided the highest stiffness and strength. In contrast, dowel-type connections exhibited superior ductility but lower stiffness and strength. The combined configuration delivered a balanced performance, integrating favorable aspects of both systems. A predictive model for each connection type was developed and validated against the experimental data, demonstrating satisfactory accuracy and reliable prediction of failure modes. These findings highlight the potential of optimized shear connections to advance sustainable bamboo–concrete composite construction, while also revealing the significant influence of bamboo’s natural variability, such as differences in diameter, node geometry, straightness, and material properties, on structural performance. Full article

This study aimed to assess how different resin matrix formulations affect the fatigue resistance of resin dental composites. Model dental composites were formulated using six distinct monomer mixtures: two Bis-GMA (bisphenol A-glycidyl methacrylate):TEGDMA (triethylene glycol dimethacrylate) (60:40 and 80:20 mole%), two UDMA (urethane dimethacrylate):TEGDMA (60:40 and 80:20 mole%), one Bis-GMA:UDMA:TEGDMA (35:35:30 mole%), and one Fit852:UDMA:TEGDMA (35:35:30 mole%). Cyclic fatigue resistance (CFR) of the resin composites was measured in a biaxial test mode using staircase analysis. Additional evaluations included biaxial flexural strength (BFS), degree of conversion (DC), water sorption (WS), and viscoelastic properties of the unfilled resins, such as the storage modulus (E′), loss modulus (E″), tan δ (E″/E′), and stiffness (k′). Data were subjected to one-way ANOVA with Tukey post hoc analyses. Pearson correlation and stepwise regression analyses were conducted to examine the relationships among variables. The UT6040 model composite exhibited the highest CFR (82.61 ± 8.83 MPa), significantly outperforming other formulations. Tan δ of the resin matrix showed the strongest correlation with CFR (r = 0.974), and was also shown to be the most influential predictor for the CFR of the particulate composites. The composition of the resin matrix has a significant impact on the CFR of dental composites. Among the properties evaluated, the viscoelastic parameter tan δ emerged as a strong and reliable predictor of CFR, emphasizing the importance of targeting viscoelastic behavior in the design of dental composite formulations. Full article

Polyampholyte hydrogels are promising for load-bearing biomedical applications, but the link between composition and compression behavior remains unclear. In this study, we investigate how initial monomer concentration and a neutral comonomer influence swelling and mechanical properties in AMPS–APTAC networks. Terpolymeric AMPS–APTAC–DMAAm hydrogels were prepared with monomer concentrations from 1 to 2 M, MBAAm levels from 1 to 5 mol%, and DMAAm fractions from 0 to 0.16. Swelling was measured in water. Unconfined compression tests at 3 mm·min⁻¹ provided stress–strain curves, Young’s modulus (E), fracture stress (σ_f), fracture strain (ε_f), and toughness (W) up to 99% strain. Increasing the monomer concentration produced denser networks, lower swelling, and higher stiffness. For C2M1, E reached 35.4 kPa, σ_f reached 0.8 MPa, ε_f was 82%, and W was 65.6 kJ·m⁻³. Adding DMAAm strengthened the gels through reversible associative interactions. At z = 0.06, σ_f increased to 4.28 MPa and W to 196.0 kJ·m⁻³. At z = 0.16, E increased to 103.0 kPa, while σ_f was 2.34 MPa and W was 191.6 kJ·m⁻³. Swelling decreased when monomer or crosslinker content increased. These results show that monomer concentration and DMAAm-mediated associations act as separate design variables that can be tuned to optimize stiffness, strength, and toughness in AMPS–APTAC polyampholyte hydrogels. Full article

In recent years, agricultural production activities have been advancing towards mechanization and intelligence to bridge the growing gap between the high labor intensity and time sensitivity of harvesting operations and the limited labor resources. As the component that directly interacts with target crops, the end-effector is a crucial part of agricultural harvesting robots. This paper first reviews their materials, number of fingers, actuation methods, and detachment techniques. Analysis reveals that three-fingered end-effectors, known for their stability and ease of control, are the most prevalent. Soft materials have gained significant attention due to their flexibility and low-damage characteristics, while the emergence of variable stiffness technology holds promise for addressing their issues of poor stability and fragility. The introduction of bionics and composite concepts offers potential for enhancing the performance of end-effectors. Subsequently, starting from an analysis of the biomechanical properties of fruits and vegetables, the relationship between mechanical damage and the intrinsic parameters of produce is elucidated. On the other hand, practical and efficient finite element analysis has been applied to various stages of end-effector research, such as structural design and grasping force estimation. Given the importance of compliance control, this paper explores the current research status of various control methods. It emphasizes that while hybrid force–position control often suffers from frequent controller switching, which directly affects real-time performance, active admittance control and impedance control directly convert external forces or torques into the robot’s reference position and velocity, resulting in more stable and flexible external control. To enable a unified comparison of end-effector performance, this review proposes a progressive comparison framework centered on control philosophy, comprising the ontological characteristic layer, physical interaction layer, feedback optimization layer, and task layer. Additionally, in response to the current lack of scientific rigor and systematization in performance evaluation systems for end-effectors, performance evaluation criteria (harvest success rate, harvest time, and damage rate) are defined to standardize the characterization of end-effector performance. Finally, this paper summarizes the challenges faced in the development of end-effectors and analyzes their causes. It highlights how emerging technologies, such as digital twin technology, can improve the control accuracy and flexibility of end-effectors. Full article

Material Extrusion (MEX) additive manufacturing offers a versatile platform for producing lightweight, structurally optimized components. This study investigates the simultaneous optimization of topology and infill density using three polymer composite materials, PPA-CF, PAHT-CF, and ABS, selected for their mechanical performance, cost efficiency, and printability. Cylindrical specimens were fabricated with nine mass retention levels (100% to 33%) by systematically varying topology and infill parameters. Compression testing was conducted to assess stiffness, deformation behavior, and structural integrity under simulated operational loads. Results show that combining topology optimization with variable infill density can significantly reduce material usage and manufacturing time while maintaining mechanical reliability across all three materials. PAHT-CF demonstrated the highest strength-to-weight performance, while ABS offered cost-effective alternatives for less demanding applications. The study establishes clear relationships between design strategies and material behavior, enabling the production of net-shape satellite support structures with fewer design iterations and improved throughput. These findings support the adoption of resource-efficient manufacturing practices and provide a framework for sustainable, low- to mid-volume production in high-value manufacturing industries. Overall, the integration of design and material optimization advances the potential of additive manufacturing for scalable, cost-effective, and environmentally conscious aerospace solutions. Full article

Soft robots often suffer from insufficient load capacity due to the softness of their materials. Existing variable stiffness technologies usually introduce rigid components, resulting in decreased flexibility and complex structures of soft robots. To address these challenges, this work proposes a novel wrist-gripper composite soft end-effector based on the weaving jamming principle, which features a highly integrated design combining structure, actuation, and stiffness. This end-effector is directly woven from pneumatic artificial muscles through weaving technology, which has notable advantages such as high integration, strong performance designability, lightweight construction, and high power density, effectively reconciling the technical trade-off between compliance and load capacity. Experimental results demonstrate that the proposed end-effector exhibits excellent flexibility and multi-degree-of-freedom grasping capabilities. Its variable stiffness function enhances its ability to resist external interference by 4.77 times, and its grasping force has increased by 1.7 times, with a maximum grasping force of 102 N. Further, a grasping force model for this fiber-reinforced woven structure is established, providing a solution to the modeling challenge of highly coupled structures. A comparison between theoretical and experimental data indicates that the modeling error does not exceed 7.8 N. This work offers a new approach for the design and analysis of high-performance, highly integrated soft end-effectors, with broad application prospects in unstructured environment operations, non-cooperative target grasping, and human–robot collaboration. Full article

This study examined sarcopenia severity effects on body composition, physical performance, and mechanical properties of gait-related muscles in older women. Forty-one women aged ≥70 years participated and were classified by the following criteria: non-sarcopenia (NS, n = 15), functional sarcopenia (FS, n = 10), sarcopenia (SP, n = 9), and severe sarcopenia (SS, n = 7). Assessments included body composition, physical performance, and muscle tone, stiffness, and elasticity of the tibialis anterior (TA) and gastrocnemius medialis (GM). Group differences were analyzed using one-way ANOVA with Bonferroni post hoc tests (α = 0.05). SP and SS groups had lower body weight, BMI, appendicular skeletal muscle mass, and calf circumference compared with NS. FS demonstrated poorer physical performance than SP across all variables, with six-meter gait speed lower than SS (p < 0.05). SP exhibited significantly higher TA muscle tone, GM muscle tone and GM stiffness than NS (p < 0.05, p < 0.01, p < 0.05, respectively), while TA elasticity was significantly lower in SP (p < 0.01). These findings indicate that sarcopenia severity negatively influences body composition, muscle function, and mechanical properties, with functional sarcopenia showing the greatest impairment in performance. Early detection and targeted interventions are therefore critical to mitigate functional decline in older women. Full article

Sports footwear is widely used across a range of physical activities. A key factor distinguishing running shoes from other types of footwear is the “drop,” the millimeter difference between the heel and the forefoot. This study aimed to analyze the influence of different drops (0, 5, and 10 mm) on ground reaction forces during walking and to examine the effects of sex and body mass index (BMI) under these conditions. An observational, descriptive, and cross-sectional study was conducted with 117 participants (56 men and 61 women). The Dinascan/IBV^® dynamometric platform (Instituto de Biomecánica de Valencia, Valencia, Spain) was used to measure ground reaction forces during walking (braking, take-off, propulsion, and swing forces), walking speed, and stance time. The descriptive analysis revealed comparable values for the left and right limbs, with slightly higher values observed in the right limb. Statistically significant differences were found in stance time, braking force, and swing force between the 0 mm and 10 mm drop conditions. Take-off force showed highly significant differences when comparing the 0–5 mm and 0–10 mm drop conditions. Sex-based differences were observed in all variables at the initial proposed drop condition of 0 mm, except for walking speed, possibly due to anatomical and physiological differences. Significant differences were found in stance time at 0 mm drop, braking force, and propulsion force. Highly significant values were obtained for take-off force and during the swing phase. A strong correlation was found between ground reaction forces and BMI with the different proposed drops in all forces studied, except for the support force, where a moderate correlation was obtained. Although shoe drop was found to influence ground reaction forces in this study, it is one of several factors that affect gait biomechanics. Other footwear characteristics, such as sole stiffness, material composition, weight, and elasticity, also play important roles in walking performance. Therefore, shoe drop should be considered an important but not exclusive parameter when selecting footwear. However, these results are limited to healthy young adults and may not be generalizable to other age groups or populations. Full article

The waviness defect, a common manufacturing flaw in composite structures, can significantly impact the mechanical performance. This study investigates the effects of wrinkles on the ultimate load and failure modes of two Carbon Fiber Reinforced Composite (CFRC) laminates through compressive experiments and simulation analyses. The laminates have stacking sequences of [0]_10S and [45/0/−45/90/45/0/−45/0/45/0]_S. Each laminate includes four different waviness ratios (the ratio of wrinkle amplitude to laminate thickness) of 0%, 10%, 20% and 30%. In the simulation, a novel multiaxial progressive damage model is implemented via the user material (UMAT) subroutine to predict the compressive failure behavior of wrinkled composite laminates. This multiscale analysis framework innovatively features a 7 × 7 generalized method of cells coupled with stress-based multiaxial Hashin failure criteria to accurately analyze the impact of wrinkle defects on structural performance and efficiently transfer macro-microscopic damage variables. When any microscopic subcell within the representative unit cell (RUC) satisfies a failure criterion, its stiffness matrix is reduced to a nominal value, and the corresponding failure modes are tracked through state variables. When more than 50% fiber subcells fail in the fiber direction or more than 50% matrix subcells fail in the transverse or thickness direction, it indicates that the RUC has experienced the corresponding failure modes, which are the tensile or compressive failure of fibers, matrix, or delamination in the three axial directions. This multiscale model accurately predicted the load–displacement curves and failure modes of wrinkled composites under compressive load, showing good agreement with experimental results. The analysis results indicate that wrinkle defects can reduce the ultimate load-carrying capacity and promote local buckling deformation at the wrinkled region, leading to changes in damage distribution and failure modes. Full article

This study examines the influence of printing parameters and filament composition on the mechanical properties of 3D printed parts, building upon prior research in fused deposition modeling. Two combinations of printing parameters, 75% infill, 0° orientation, four outer shells, with either gyroid and 3D Honeycomb infill patterns—were analyzed across eleven materials, including acrylonitrile butadiene styrene, polylactic acid, polylactic acid-based composites, polyethylene terephthalate glycol, and high-impact polystyrene. Tensile, compression, and bending tests were performed on the printed specimens to determine stiffness and elastic modulus. Each material demonstrated different levels of variability and sensitivity to printing parameters under the various loading conditions, emphasizing that no single configuration is optimal across all scenarios. For example, the gyroid pattern led to increases up to ~35% in bending modules for common thermoplastic filaments and ~30% for stone-filled polymers, while in tensile stiffness, variations between infill patterns remained below 5% for other conventional polymers. These findings underline the load-specific nature of optimal parameter combinations and the influence of material-specific characteristics, such as filler content or microstructural homogeneity. This study provides quantitative insights that can support application-driven parameter selection in additive manufacturing, offering a comparative dataset across widely used and emerging filaments. Full article