Search Results (3,670)

Micro- and nanoplastics (MNPs) are widely detected in food, drinking water, food-contact materials, and human biological samples. This narrative review evaluates whether experimental evidence supports a role for MNPs as modifiers of food-allergen digestion, intestinal-barrier function, microbiota composition, and immune tolerance. In vitro studies indicate that protein-corona formation can alter allergen conformation, epitope accessibility, and proteolysis, although effects vary by polymer, particle size, dose, and digestive model. Rodent studies provide evidence that MNP exposure can disrupt epithelial integrity, induce oxidative and inflammatory signaling, and modify microbiota-dependent immune regulation. More direct food-allergy models have reported exacerbation of ovalbumin- and cow’s-milk-allergic responses, including Th2 polarization and changes in dendritic cell and regulatory T-cell compartments. Infants may represent a susceptible and highly exposed population because of immature digestive and barrier function and the use of plastic feeding equipment; however, the available pediatric evidence is limited to exposure studies and simulated digestion. The effect of MNP exposure on the incidence of food allergies, reaction thresholds, or clinical severity in humans has not yet been studied. Accordingly, current findings support biological plausibility and identify research priorities, but they do not establish causality in humans. Full article

Carbon-fiber-reinforced polymer (CFRP) reinforcement is a potential alternative to steel in corrosive environments. However, CFRP is elastic without ductility, and the seismic performance of CFRP-reinforced concrete (RC) columns is inadequately understood. This study characterizes the intrinsic seismic response of concrete columns reinforced with CFRP cable-type bars and spirals under recorded near-fault ground motions. Three reference steel-RC columns are designed as seismic-resistant, non-seismic-resistant, and with post-cracking stiffness equivalent to the CFRP-RC column. The CFRP-RC and seismic-resistant steel-RC columns were tested under cyclic loading, and the results validated finite element (FE) models. Validated models simulated four columns under cyclic loading, and under 11 near-fault records matched to a capacity-derived elastic target spectrum. The results, bounded by selected ground motions and material constitutive models, show that: (1) The tested CFRP-RC column dissipated about 50% less energy than the steel-RC reference; (2) No material-level failure criterion was met under the suite, although peak base shears exceeded the nominal quasi-static capacities; (3) The CFRP-RC column developed the largest transient drift but minimal residual drift, whereas the steel-RC columns limited transient amplitude via hysteretic dissipation yet accumulated permanent offsets; (4) Response of the CFRP-RC column depends on ground motion energy delivery characteristics: concentration, symmetry, and duration. Full article

Polymeric micelles represent a fundamental self-assembled architecture of gel-based soft materials and have emerged as promising nanocarriers for anticancer drug delivery. Their performance is largely governed by the block composition of constituent copolymers, and understanding their self-assembly behavior provides critical insights into the rational design of gel-related drug delivery systems. In this work, dissipative particle dynamics (DPD) simulations were performed to systematically investigate two types of mixed drug-loaded micellar systems self-assembled from a triblock copolymer mPEG-b-poly(2-(diethylamino)ethyl methacrylate)-b-PMMA (PDEAEMA, hereafter referred to as the DMA block for brevity) with either a diblock copolymer PDEAEMA-b-PMMA (polymer B) or PPEGMA-b-PDEAEMA (polymer C). By tailoring the ratios of hydrophobic (MMA, the constituent block of PMMA) and pH-sensitive (DMA) blocks, the protonation-responsive behavior, structural stability, drug loading capacity, and release kinetics of the micelles were comprehensively examined. The simulation results demonstrate that: (1) increasing the hydrophobic block ratio accelerates the protonation-triggered micellar swelling and drug release because the increased hydrophobic content enhances the core compactness which, upon protonation, generates a stronger driving force for chain extension, yet an optimal ratio (+16 MMA units) exists beyond which excessive hydrophobic blocks suppress release due to core densification; (2) increasing the pH-sensitive block ratio significantly enhances the maximum drug loading capacity (from 9.83% to 12.22% for the A/C system), but exerts only limited influence on the release rate; (3) the A/C mixed micelles with higher PEG content exhibit superior structural stability and drug loading capacity, while the A/B system with higher MMA content displays more sensitive pH-responsiveness. These findings reveal a competing mechanism between “protonation-driven force” and “structural resistance,” providing mesoscopic theoretical guidance for the rational design of pH-responsive polymeric nanocarriers and self-assembled soft materials via block ratio modulation. Full article

Advanced engineering applications increasingly demand high-performance polymers with exceptional mechanical and thermal properties; however, predicting their processing behavior remains challenging due to complex rheological responses and the lack of integrated experimental–simulation frameworks. This study introduces a novel integrated experimental–computational methodology that combines comprehensive rheological characterization, multi-model fitting, injection molding simulation, and multiphysics finite element analysis (FEA) to investigate the processing capabilities of Polyether Ether Ketone (PEEK) for aircraft bearing applications. Unlike conventional approaches that treat rheological analysis, processing simulation, and structural assessment separately, our framework establishes a coupled material–process–performance relationship through: (i) systematic thermal and mechanical characterization, establishing PEEK’s high melting temperature (343 °C), degradation temperature (575 °C), and tensile strength (95 MPa); (ii) comparative rheological model fitting, demonstrating that the Carreau–Yasuda model accurately predicts non-linear flow behavior with R² = 0.97, outperforming simpler Power Law and Cross models; (iii) CAD-based injection molding simulation, revealing homogeneous flow distribution and optimized pressure profiles; and (iv) thermo-mechanical FEA, coupling thermal expansion with structural stress analysis to evaluate bearing integrity under operational conditions. The key novelty lies in the seamless integration of experimental rheology with multiphysics simulation, validated through rigorous statistical analysis achieving low RMSE (0.6854 MPa for stress, 0.003220 mm for deformation) and high correlation coefficients (R² = 0.97). The results confirm a uniform flow distribution, stable structural performance, and reliable thermo-mechanical response, establishing PEEK’s suitability for high-performance aerospace components. This work contributes a comprehensive, scalable, and transferable framework that bridges experimental analysis and advanced simulation, enabling the predictive optimization of polymer processing parameters and significantly enhancing manufacturing reliability for industrial applications. The findings demonstrate the applicability of the experimental–computational analysis to the investigated PEEK bearing configuration under the specified processing and simulation conditions. Its specific contribution is the application of comparative rheological model fitting and experimentally characterized PEEK properties to the selected bearing geometry and processing conditions. Full article

Background/Objectives: Directly printed orthodontic appliances rely mostly on vat-photopolymerisation resins; pre-polymerised thermoplastics processed by fused deposition modelling (FDM) and selective laser sintering (SLS) are a less-explored, single-component route, but are poorly characterised. This study compared six thermoplastic material–process systems, supplied for biomedical or dental use, using a single intraoral-simulating protocol. Methods: Thin specimens (25 × 5 × 0.6 mm) of polyethylene terephthalate glycol (PETG), polycarbonate (PC), polyamide (PA), polyether-ether-ketone (PEEK) and a thermoplastic copolyester elastomer (TPC) printed by FDM, and of polyamide 12 (PA12) by SLS, underwent three-point bending and 10 min stress relaxation at 37 °C in artificial saliva (n = 5). Differences were assessed using the Kruskal–Wallis test with Dunn post hoc comparisons (Holm correction), and Fourier-transform infrared (FTIR) spectroscopy was used to compare virgin and printed materials for the five FDM polymers. Results: Apparent flexural moduli were 989 (PA12), 750 (PC), 687 (PEEK), 509 (PETG), 85 (PA) and 32 MPa (TPC), a very large material effect (ε² = 0.95), with post hoc comparisons separating only the extremes of that range. Relaxation over 10 min ranged from 2.6% (PC) to 22.1% (PA12) among the five materials in which it could be quantified, with TPC falling below the load-cell resolution; expressed as force, PA12 lost the most (0.86 N) and yet still delivered 3.01 N, which was above the initial force of PEEK, PETG, PA and TPC, though not separable from that of PC, which retained 97.4% of its own. Virgin and printed spectra were concordant (Pearson r ≥ 0.986, against ≤ 0.80 between different materials). Conclusions: The PA12/SLS system was the stiffest, followed by PC and PEEK, but, as the only laser-sintered material, its polymer and process effects cannot be separated. PETG and PC combine useful stiffness with accessible FDM; PA and TPC are far more compliant. These specimen-level findings provide a screening basis for selecting material–process systems for printed orthodontic appliances, preceding device-level validation. Full article

Injection molding is a plastic material processing technique used in the polymer industry. Because it is a complex process that requires injection cycles to achieve the desired aesthetic quality in the molded parts, it is essential to evaluate and configure all process parameters to predict and reduce defects, thereby decreasing the processing time and energy consumption. This study presents the results of tests performed on molded HDPE parts, including modeling and simulation using ANSYS^® (2025 R1), a design of experiments (DOE), and 3D scanning of the molded parts. The study compares the behavior of defects (warpages and sink-marks) in molded parts using 3D scanning with the results obtained from coupled thermal-structural field finite element simulations. These simulations were performed using software to assess the residual thermal stress of the ejection phase. The results visually display information that helps designers and engineers in the polymer processing sector evaluate molding-process failures using different software. Full article

Vaginal drug delivery offers a critical route for local treatments but is limited by short formulation residence times. This study describes a thermosensitive in situ gel prepared by the cold-dissolution method from a ternary blend of Pluronic F127, Carbopol 940, and HPMC for localized vaginal therapy. We used ibuprofen as a model drug selected for its reported anti-inflammatory and antiproliferative activity. The hydrogels exhibited a constant gelation temperature of 28 °C and high viscosity under simulated physiological conditions; ibuprofen incorporation further reduced susceptibility to gravitational leakage. FTIR, XRD, and DSC analyses confirmed stable physical cross-linking of the polymer network and amorphous molecular dispersion of ibuprofen. Peppas–Sahlin modelling revealed a controlled, sustained release profile (>50% over 24 h) predominantly governed by Fickian diffusion (69%). The blank hydrogel exhibited high biocompatibility (>75% viability). In contrast, the ibuprofen-loaded matrix exhibited a concentration-dependent cytotoxic effect on HeLa cervical cancer cells, reducing cell viability to ~12% at the full extract concentration. Overall, this ternary hydrogel platform represents a stable, promising vehicle for sustained local administration of ibuprofen in the vaginal microenvironment. Full article

Microplastics (MPs) are emerging pollutants widespread in aquatic environments; however, their effects across the different life stages of aquatic organisms remain poorly understood. This systematic review integrates recent experimental results on the developmental, physiological, and neurobehavioral effects of MP exposure on zebrafish (Danio rerio), a popular model organism for ecotoxicology research. A PRISMA-guided search using Web of Science (WoS) and Scopus as databases generated 581 articles, which were screened to 60 eligible articles. The collated results showed that MP toxicity at various life stages of zebrafish was strongly related to the physicochemical properties of MPs and exposure conditions. In terms of developmental toxicity, peer-reviewed publications assessing specific MP physicochemical properties—polymer type, size, concentration, shape, and degree of aging—reported concentration-dependent effects, with increasing MP concentrations generally associated with growth inhibition, cardiac dysfunction, increased malformations, and lower hatching rate, particularly at ≥10 mg/L to ≥100 mg/L. However, several studies noted that under particle-based exposure scenarios, MP toxicity exhibited threshold-like or non-monotonic responses, attributed to aggregation, bioavailability, and uptake dynamics. Weathered and artificially aged MPs exhibited higher embryotoxicity and neurodevelopmental toxicity, including changes in gene expression of neurons, decreased integrity of motor neurons, and impaired retinal development, compared with “virgin” MPs. In terms of physiological endpoints, oxidative imbalance like changes in the activity of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx)), lipid peroxidation, inflammation, and disruption of tight junctions have been reported as key toxicity pathways. Chronic MP exposure in zebrafish also caused changes in the gut microbiota, hepatic metabolism, endocrine disruption, reproductive damage, thyroid function disruption, and genotoxicity in zebrafish. In terms of neurobehavioral effects, changes in locomotor activity, anxiety response, neurotransmitter homeostasis, and acetylcholinesterase function, have been observed, in both larvae and adults, with a potentiation effect in aged MP exposure. Finally, this systematic review found major limitations for inter-study comparisons because of inconsistencies and differences in methodology applied related to MP concentration, simulation of natural MP aging, and MP dose measurements. Full article

With the continuous development of deep oil and gas resources, the role of weighted fracturing fluids in reducing wellhead operating pressure has become increasingly important. However, the turbulent frictional drag behaviors of weighted fracturing fluids in pipes have not been explored systematically. In this study, the frictional drag characteristics and flow behaviors of non-weighted and weighted fracturing fluids in pipes are investigated at different flow rates, densities, pipe diameters, and rheological parameters via steady-state rheological tests and pipe flow friction experiments, together with large-eddy simulation and a power-law constitutive model for generalized Newtonian fluids. The main findings are as follows. The drag reduction rates of non-weighted polyacrylamide solutions basically increase with flow rate, and the optimal molecular weight of 600–700 × 10⁴ corresponds to the highest drag reduction rate of 62%, while excessively large molecular weights weaken drag reduction effectiveness due to enhanced chain entanglement. The types of weighting salts have a significant effect on drag reduction performance. The 20% KCl system obtains the highest drag reduction rate of 64.8%, while the high-density CaBr₂ system obtains the lowest rate of 42.3% because of the combined effects of fluid density, polymer concentration, and shear rheological properties. Parameter sensitivity analysis indicates that the power-law index n is the most sensitive parameter controlling frictional drag, followed by pipe diameter D. The novelty of this study lies in integrating experimental investigation, LES, and parameter sensitivity analysis to provide a theoretical basis for deep fracturing working conditions and fracturing fluids design. Full article

Four-dimensionally printed polymer honeycombs generally exhibit recoverable deformation only above the glass transition temperature, where their load-bearing capacity is greatly reduced. To address this limitation, this study proposes a recoverable kirigami honeycomb enabled by a small-strain crease design. The original non-Euclidean origami honeycomb is transformed into planar corrugated sheets through local cutting, allowing the structure to be fabricated by 3D printing, folding, and bonding. A geometric model is established to describe the relationship between crease rotation and global honeycomb deformation, revealing that large structural deformation can be achieved with limited local crease strain. Polylactic acid (PLA) specimens with weakened creases are designed and tested to evaluate their shape-memory recovery. The results show that PLA maintains good thermally induced recovery after low-temperature bending, with recovery ratios reaching up to 96.7%. Finite element simulations further confirm that the weakened creases remain within a small strain range even under 180° bending, preventing local failure during large deformation. A stable-state prediction model based on the minimum potential energy principle is developed and validated by experiments and simulations. The predicted stable height agrees well with the experimental result. This work provides a feasible strategy for 4D-printed kirigami honeycombs capable of large deformation below the glass transition temperature followed by thermally activated recovery, with potential applications in deployable structures and temperature-responsive mechanical metamaterials. Full article

A multiscale computational framework is presented to assess the effect of voids that may arise from a scarf repair and its influence on the post-repair lifetime of wind turbine blades. The approach links a full scale blade model with a detailed repair region model and a microscale representation of polymer adhesives containing voids. Boundary conditions from the global blade model are transferred to the scarf repair model, which subsequently provides input to a microscale representative volume element (RVE) of the adhesive containing voids using the submodelling technique. This RVE is combined with a continuum damage mechanics formulation to simulate high-cycle fatigue and estimate the lifetime for different void contents. The effect of void content resulting from scarf repair is evaluated under both quasi-static and high-cycle fatigue loading, enabling lifetime predictions. In the simulations, it was demonstrated that the lifetime of repaired blade is 4 times lower for the repair with 4% void content as compared with the repair with 1% void content. Full article

Microcracks in concrete are a key factor affecting structural durability, and traditional repair methods struggle to achieve the long-term sealing of deep-seated microcracks. Self-healing bio-concrete, based on the technology of microorganism-induced calcium carbonate precipitation, utilises pre-embedded microbial repair agents to mimic the self-healing mechanisms of living organisms, thereby offering a solution to the problem of microcracks in concrete. However, current research in this field has yet to establish a quantitative framework linking the successive stages from damage perception to functional recovery. To this end, this paper critically reviews the core process-driven mechanisms of this technology, covering the complete chain from damage sensing and triggering, mass transport and microbial metabolism to the formation of mineralisation products and functional recovery. Furthermore, this paper identifies three major bottlenecks: the survival of bacteria in harsh matrix environments, the adverse impact of carriers on mechanical properties, and performance discrepancies between laboratory conditions and on-site conditions. Building on this, this paper further explores key influencing factors such as the selection and cultivation of alkali-tolerant microbial strains, the optimisation of carrier systems, and temperature control. In particular, the paper introduces multi-scale numerical simulation methods to establish coupled convection–diffusion–reaction mass transfer equations within cracks as well as kinetic models for substrate consumption and urease-catalysed microbial processes. These models enable the quantitative prediction of reagent concentration fields, the evolution of supersaturation, and the time required for complete crack sealing whilst taking into account the regulatory role of extracellular polymers. This paper aims to advance research into self-healing bio-concrete from an empirical trial-and-error approach towards predictable, rational design. It also recommends that future efforts should focus on the development of self-sensing and self-adaptive healing systems and on the durability assessment of self-healing bio-concrete under real-world service conditions. Full article

Dilute-solution properties are important sources of information on the structure of macromolecules. Analyzing experimental data and extracting information on structural properties require theoretical and computational resources. The resources needed to study rigid particles are manageable; however, studying flexible particles is more challenging. This is because, unlike rigid bodies, and as a consequence of the conformational variability arising from flexibility, flexible particles do not have a definite size and shape. In addition to their overall translational and rotational Brownian motion, the dynamics of flexible particles in solution has an internal component: size/shape conformational fluctuations. In order to facilitate the study of flexible macromolecule hydrodynamics, we have implemented existing theories within several computer programs. MONTEHYDRO combines Monte Carlo simulations based on the importance-sampling algorithm to generate conformations from which, in addition to conformational quantities, the hydrodynamic properties of flexible particles can be obtained using rigid-body treatment. SIMUFLEX is a suite based on a Brownian dynamics simulation of macromolecules, comprising BROWFLEX, for the generation of trajectories, and ANAFLEX, for the calculation of static and time-dependent properties as well as the simulation of single-particle events. In this paper, we present some concepts which are fundamental to the methods implemented in those computational tools, as well as examples of their utilization in various biomacromolecule applications, with a particular emphasis on double-stranded DNA in various cases: coarse-grained double-helical models for moderately short DNA; the worm-like model treatment of DNA over an extremely wide range of sizes (from 8 to 200,000 base pairs); and the problem of the anomalous rotational-speed dependence of the sedimentation coefficient of very long DNA. SIMUFLEX has also been particularly useful for studying intrinsically partially disordered proteins, whose structure comprises both ordered, globular domains as well as flexible tail and linker chains. To illustrate applications in the field of synthetic polymers, we describe a study on dendrimers, with aspects related to drug delivery in targeted therapies. Full article

Carboxylate-ligand-based coordination polymers and metal complexes form structurally adaptable crystalline systems, spanning discrete complexes, one-dimensional chains, two-dimensional layers, three-dimensional frameworks, and MOF-like architectures. This adaptability arises from diverse carboxylate binding modes and metal coordination preferences; auxiliary N/O donors are included only when carboxylate coordination remains central. However, the increasing availability of structural and electronic descriptors has not always been matched by equally rigorous validation of structure–function relationships. Hirshfeld surface analysis, energy-framework analysis, density functional theory, adsorption simulation, molecular docking, and machine learning are descriptor-generating methods; neither a method nor its output alone establishes descriptor-guided design. This review critically examines carboxylate-based coordination systems from the perspective of descriptor-guided function-oriented design. We discuss ligand-level regulation, metal-center effects, dimensional evolution, and what supramolecular, electronic, adsorption-related, and biological descriptors can and cannot prove. Functional studies covering luminescence and sensing; catalysis, adsorption, and small-molecule transformations; and bioactivity are evaluated by evidence strength. A claim-centered Descriptor-to-Function Evidence Ladder distinguishes structure reporting, descriptive descriptor use, post hoc association, controlled comparative trends, mechanism-supported validation, and prospective experimental confirmation. It evaluates a specific descriptor–function relationship rather than overall paper quality. Future progress should rely on standardized reporting, comparative structural series, function-specific validation, and transferable descriptor–function relationships. Full article

Glass fiber-reinforced polymer (GFRP) is widely used in wind power, construction, and aerospace for its superior properties. However, studies on its blown-sand erosion degradation and prediction remain limited. This study investigates the degradation and prediction of blown-sand erosion behavior in GFRP strips using a one-factor-at-a-time (OFAT) experimental design. Simulated experiments quantify the effects of factors such as erosion angle, velocity, sand flow rate, and erosion time on mechanical behavior. Results show that epoxy-layer deformation and internal fiber fracture increase with erosion angle and velocity. The tensile strength decreased by approximately 16.8% at an erosion angle of 90° when the velocity, sand flow rate, and erosion time were fixed at 26 m/s, 55 g/min, and 30 min, respectively. At an erosion velocity of 31 m/s, with the erosion angle, sand flow rate, and erosion time fixed at 90°, 55 g/min, and 30 min, respectively, the strength reduction reached 28%. Under a 45 g/min sand flow rate, the strength reduction reached 6%, while extending the erosion time to 50 min led to a decrease of 35%. Furthermore, a particle swarm optimization (PSO)-assisted, interpolation-based inverse identification model was established to back-calculate erosion parameters from measured strain fields. The mean in-sample reconstruction error was approximately 4.2%, whereas leave-one-condition-out validation yielded an overall mean error of 31.8%, with factor-specific errors ranging from 12.8% to 43.8%, indicating limited generalization to unseen conditions. This work elucidates the progression of material degradation from initial damage to severe failure and provides laboratory reference data for understanding the post-erosion residual behavior under the investigated erosion-only conditions. Full article