Search Results (5,522)

Fibrous polyacrylonitrile (PAN) is a versatile platform for solid-phase analytical chemistry because of its chemically transformable nitrile groups, mechanical robust-ness, and favourable fibre morphology. This review critically examines PAN-based fi-brous sorbents for sorption–spectroscopic analysis (SSA) of toxic metal ions, focusing on polyamine-modified PAN/polyethylenepolyamine/1,2-dichloroethane (PPD) and PAN/polyethylenepolyamine/acrylonitrile (PPA) matrices, iminodiacetate-containing fibrous ion-exchange (FIBAN) fibres, triethanolamine-modified PAN (PAN-T), and electrospun amidoximated PAN nanofibres (AOPAN). Relationships among polymer composition, fibre morphology, surface functionalisation, reagent immobilisation, ion transport, and optical response are evaluated with respect to sensitivity, selectivity, stability, reuse, and practical applicability. Particular attention is given to electrostat-ic/physical versus covalent immobilisation, matrix interference, and the distinction between adsorption capacity and direct solid-phase optical performance. Representa-tive systems include PPD–Arsenazo III for Pb(II), with a minimum detectable concen-tration of 0.24 μg L⁻¹, and AMADA immobilised on a polyeth-ylene-polyamine-modified PAN matrix for Mn(II), with a reported determination limit of 0.02 μg mL⁻¹. The review also considers sustainability, automation, nanostructured architectures, additive manufacturing, and portable optical detection. Current evi-dence indicates that no single PAN architecture is universally superior; future progress requires improved sorbent standardisation, systematic interference and leaching stud-ies, reproducible optical calibration, and validation under realistic sample conditions. Fibre diameter and porosity are also discussed as coupled determinants of diffusion, scattering, and reproducibility. Full article

Background/Objectives: Alginate hydrogels are widely used in tissue engineering; however, their reported properties vary significantly due to differences in formulations and processing conditions, which limits direct comparison across studies. This study aims to systematically evaluate the relative and combined effects of alginate viscosity grade, polymer concentration, and CaCl₂ crosslinking concentration on hydrogel structural, mechanical, and biological behaviour. Methods: Hydrogels were prepared using three commercially available alginates of low, medium, and high viscosity. Polymer concentration (0.5–2% w/v) and CaCl₂ concentration (2.5–10% w/v) were systematically varied under controlled fabrication conditions. Morphology was analysed using scanning electron microscopy, swelling and water uptake were quantified, mechanical properties were assessed via dynamic mechanical analysis, and cell viability was evaluated using Chinese hamster ovary (CHO) cells encapsulation over 20 days. Statistical analysis was performed using two-way ANOVA. Results: Hydrogel properties were governed by non-linear interactions between formulation parameters. CaCl₂ concentration was identified as the dominant factor influencing structural and biological outcomes, with increasing crosslinking concentration reducing pore size, swelling, and water uptake, and decreasing cell viability by up to ~60%. In contrast, polymer concentration and alginate viscosity grade primarily controlled mechanical behaviour, with increased polymer content and viscosity resulting in higher storage and Young’s moduli. Significant interaction effects confirmed that hydrogel properties are not independently tunable but depend on the combined influence of all parameters. Conclusions: Crosslinking concentration dominates structural and biological responses in alginate hydrogels, while polymer parameters modulate mechanical properties within this constraint. These findings establish a formulation-dependent trade-off between mechanical stiffness and cytocompatibility, providing a comparative framework for rational selection of alginate systems based on application-specific requirements. Full article

Composite micromechanics is commonly divided between rapid mean-field estimates and computationally intensive full-field representative-volume-element (RVE) simulations. When these routes use different files, conventions and post-processing procedures, discrepancies can reflect bookkeeping rather than mechanics. This paper introduces HARVEST (Homogenisation and Representative Volume Element Simulation Tool; version 0.7.0.dev0), a general-purpose platform that coordinates mean-field homogenisation, three-dimensional RVE generation, finite-element model preparation, solver execution, homogenisation, parameter studies and post-processing through common project, service and provenance boundaries. The numerical framework is material-agnostic, whereas verification and validation are demonstrated using polymer-based nanocomposites. The Mori–Tanaka bulk response for spherical inclusions reproduces the Hashin composite-sphere result to machine precision, independent orientation procedures agree to a relative difference of $1.6\times {10}^{-14}$, and a sequential coated-particle approximation differs from an analytical composite-sphere reference by at most $0.417$% over 24 polymer-relevant configurations. An archived full-field epoxy/silica-type campaign using kinematic uniform boundary conditions and ${20}^3$ structured cells remains within the Hashin–Shtrikman interval at five inclusion fractions, with realisation scatter below $0.4$%. For published epoxy nanocomposites, aligned halloysite-nanotube predictions differ from measured flexural moduli by $-0.89$ and $+0.48$%, while spherical carboxyl-terminated butadiene–acrylonitrile-rubber predictions differ by $-7.03$ and $-2.25$%. The main conclusion is that a shared, traceable description of constituents, morphology, loading and outputs supports rapid mean-field screening followed by selective full-field analysis using the same material definition. The principal advantage over single-route or loosely coupled workflows is cross-route consistency and reproducibility. HARVEST is applicable to formulation screening, sensitivity studies and local-field assessment in particulate, tubular, rubber-modified, porous and mixed-matrix polymer systems, and can be extended through validated constitutive, geometry, solver and result adapters. Full article

Shape memory polymers (SMPs) and their multifunctional composites have become important material systems for 4D printing because they can be processed into structures with programmed deformation and stimulus-responsive actuation. After being fixed in a temporary configuration, SMPs are able to recover their permanent shape when exposed to heat, electric or magnetic fields, and so on. This reversible shape change gives printed SMP structures functions beyond those of conventional static components, making them useful for biomedical devices, flexible electronics, and soft robotics. The performance of 4D-printed SMPs is determined not only by material chemistry but also by the design of the printed architecture and the manner in which external stimuli are applied. This review begins by covering the basic mechanisms that govern shape memory behavior in SMPs, including molecular switching, thermomechanical programming, and stimulus-controlled recovery. On this basis, representative printing methods for SMPs are compared, including stereolithography (SLA), fused deposition modeling (FDM), direct-write printing, and polymer inkjet printing. Recent applications are then considered in areas where programmed shape change has practical value, such as biomedical devices, soft robotics, and flexible electronics. The discussion also identifies unresolved problems in printing resolution, response speed, cyclic stability, structural design, and multifunctional coupling, which remain central barriers to wider use of 4D-printed SMP systems. Full article

To mitigate clay hydration and wellbore instability during deepwater drilling, a pH/temperature dual-responsive graft copolymer, hyperbranched polyethylenimine-g-poly(2-(dimethylamino)ethyl methacrylate) (HPEI-g-PDMAEMA), was designed and synthesized via free radical polymerization. Optimized synthesis at an HPEI/DMAEMA mass ratio of 1:2 with 2.4% AIBN at 70 °C for 10 h yielded a grafting ratio of 35.2% and a molecular weight of 84.3 kDa. The copolymer exhibits a tunable lower critical solution temperature (LCST) of approximately 48 °C at pH 8, decreasing with increasing pH due to tertiary amine deprotonation. Zeta potential measurements confirm that the polymer retains a positive charge (+5 mV at pH 8) under weakly alkaline conditions, enabling strong electrostatic anchoring onto negatively charged clay surfaces. Above the LCST, dynamic light scattering reveals a sharp increase in hydrodynamic diameter from ~30 nm to >200 nm, confirming a hydrophilic-to-hydrophobic transition of PDMAEMA segments that drives the formation of a hydrophobically associated gel barrier. This thermally triggered gelation is fully reversible, as evidenced by repeated heating–cooling cycles with almost complete transmittance recovery. The gel barrier drastically reduces water uptake, with inhibition performance against clay swelling at 60 °C being 18.5 percentage points higher than that at 25 °C. Hot-rolling tests demonstrate that with only 1.5 wt% inhibitor, shale recovery reaches 94.1% at 150 °C (8.8 percentage points higher than unmodified HPEI) and remains above 60% even in 20 wt% CaCl₂ or MgCl₂ brines, highlighting exceptional resistance to divalent cations. Water contact angle on treated clay surfaces increases from 18.5° to 52.6°, confirming effective surface hydrophobization. This work provides a molecular-level gel-engineering strategy where pH governs electrostatic anchoring and temperature triggers reversible hydrophobic gelation, enabling on-demand switching of clay wettability and hydration resistance under high-temperature, high-salinity conditions. Full article

This experimental study aimed to develop and evaluate a low-polymer, high-temperature water-based fracturing gel using a dual-ligand organic zirconium crosslinker regulated by sodium lactate and ethylene glycol. The crosslinker was selected by ligand screening and single-factor optimization using the apparent viscosity of LX641 gels as the primary response, and was characterized by FTIR and electron microscopy. Gelation, salt response, high-temperature shear rheology, oscillatory and steady-shear behavior, static fluid loss, gel breaking, proppant suspension, and core-permeability damage were then evaluated. The selected zirconium oxychloride octahydrate/sodium lactate/ethylene glycol/water/NaOH mass ratio was 10:6:4:15:1.2, with synthesis at 55 °C, pH 7, for 4 h. A 0.2 wt.% LX641 gel at a base-fluid/crosslinker-solution volume ratio of 100:0.5 retained an apparent viscosity of 246.84 mPa·s at 100 min after heating to 190 °C within 25 min and shearing at 190 °C for the remaining 75 min at 170 s⁻¹. The system also showed no visible settling of 10 wt.% 30-mesh ceramic proppant after 12 h, core-permeability damage of 11.98–13.65%, and visually clear broken fluid within 2 h using 0.01 wt.% ammonium persulfate at 70 °C. The results indicate that sodium-lactate/ethylene-glycol regulation can support substantial high-temperature viscosity retention at only 0.2 wt.% polymer loading, providing a low-polymer alternative for further development of high-temperature zirconium-crosslinked fracturing gels. Full article

Asphalt mixtures are heterogeneous composite materials primarily composed of mineral aggregates and asphalt binder; depending on the mixture design, they may also incorporate reclaimed asphalt pavement (RAP) and polymer-modified binders. Their long-term performance is governed by the rheological evolution of the asphalt binder and its interactions with surrounding composite constituents during aging. Existing laboratory long-term aging (LTA) protocols have been developed primarily to evaluate mixture cracking resistance; however, their ability to reproduce the high-temperature rheological evolution of recovered asphalt binders remains insufficiently understood. This study evaluated the fidelity of accelerated LTA protocols by comparing the high-temperature rheological response of binders recovered from plant-produced asphalt mixtures with the conventional benchmark of 85 °C for 5 days. Five mixtures, including one containing an unmodified PG 67-22 binder with RAP and four containing SBS-modified PG 76-22 binders with varying RAP contents, were characterized using continuous high-temperature performance grade (PG-HT), dynamic shear rheometer rutting parameter (|G*|/sinδ), zero-shear viscosity, multiple stress creep recovery, and interrupted shear flow. Among the investigated protocols, loose-mixture aging at 135 °C for 6 h showed the closest agreement with the benchmark rheological response, whereas 135 °C for 8 h and 120 °C for 20 h produced greater rheological stiffening relative to the benchmark. The unmodified PG 67-22 binder exhibited the greatest aging sensitivity, while SBS-modified binders showed closer agreement overall. Full article

Tower cranes are highly vulnerable to seismic excitation owing to their slender geometry and pronounced dynamic behaviour. Although carbon fibre reinforced polymer (CFRP) materials offer significant lightweight potential, and damping devices are widely adopted for seismic protection, their combined application to tower cranes has received limited attention. This study numerically investigates the seismic response of a rearing jib tower crane equipped with a CFRP jib and base joint dampers. A finite element model was developed and analysed under four critical operating configurations through static structural, modal and response spectrum analyses in accordance with the Italian Building Code (NTC 2018). The performance of the CFRP solution was compared with that of a conventional steel crane, while two damper configurations with different stiffness values were also assessed. The proposed lightweight design reduced the total crane mass by 34% and the jib weight by 77%. Compared with the steel configuration, the CFRP solution decreased static displacements by 38–56% and equivalent stresses by 22–44%. Under seismic loading, the adoption of joint dampers reduced the maximum equivalent stress by up to 35%, while increasing structural displacements by 5–19% because of the lower support stiffness. The results demonstrate that combining CFRP lightweight design with seismic damping devices effectively improves the earthquake performance of tower cranes while maintaining structural safety. Full article

In this study, a method for introducing titanium dioxide nanoparticles (TiO₂NPs) into the polymer matrix of a ferroelectric copolymer of vinylidene fluoride with tetrafluoroethylene P(VDF-TFE) is proposed and optimized. A comprehensive analysis showed that TiO₂NPs content has a significant effect on the structure formation processes in the polymer matrix, the degree of crystallinity, phase composition, and surface morphology of the composites. By optimizing the amount of doped nanoparticles, it is possible to increase the electrical strength and permittivity of the material, as well as enhance the piezoelectric response compared to a film without TiO₂NPs. The introduction of TiO₂NPs into the P(VDF/TFE) polymer matrix promotes efficient polarization of the composite film without preliminary high-temperature orientational drawing. The approaches presented in this study can simplify process operations in the manufacture of flexible sensors, wearable electronics, and other devices that require a combination of piezoelectric activity and high electrical strength. Full article

Rapid and accurate quantification of residual guar gum in bauxite slurry flocculation is a critical bottleneck for closed-loop control of flocculant dosage. In this study, we systematically compared the anti-interference performance of the two UV-Vis spectrophotometer approaches, the single-wavelength absorbance method (A₂₆₃) and the peak-trough difference method (ΔA), in complex slurry matrices. Our results revealed that the two methods respond differently to pH and salt concentration variations, leading to the proposal of a dual-mode synergistic detection strategy. The A₂₆₃ method provides quantification under the specific conditions tested within the ranges of pH 3.0–8.0 and CaCl₂ concentration below 4.5 mmol/L. Beyond these boundaries, deviations from the Beer-Lambert law occurred, attributable to conformational transitions or salting-out aggregation of the polymer chains. In contrast, the ΔA method partially mitigated background drift through differential calculation and exhibited a more stable signal trend than A₂₆₃ across the tested ranges (pH 2.0–11.0, CaCl₂ 0–18 mmol/L), suggesting its potential utility as a semi-quantitative indicator in challenging matrices. However, its quantitative precision was constrained by small absolute signal values and systematic dependence on pH and salt conditions. Based on these findings, we propose a synergistic strategy-preferring the A₂₆₃ method under routine conditions while recommending the ΔA method for high-salinity or wide-pH scenarios- and accordingly define the preliminary applicability boundaries based on signal response observations at a single concentration. Flocculation–sedimentation tests confirmed that the method successfully determined the optimum dosage (5.0 g/kg dry slurry), at which the residual concentration in the supernatant correlated negatively with the sedimentation rate (R² > 0.95). The supernatant matrix after sedimentation (pH ≈ 7.1, low ionic strength) fell exactly within the safe window. This work provides a methodological reference for spectrophotometric quantification of trace organics in turbid, saline, and pH-variable slurry systems, and lays an analytical foundation for intelligent dosage control in bauxite slurry dewatering. Full article

Microplastics are increasingly recognized as emerging contaminants with potential toxicological effects on aquatic organisms. Among widely used industrial polymers, poly(methyl methacrylate) (PMMA) has been detected in environmental matrices, raising concerns regarding its biological impacts. This study evaluated the developmental toxicity of 40 µm spherical PMMA microplastics in zebrafish (Danio rerio) using a standardized early-life stage exposure (3 hpf–6 dpf). Before exposure, particles were physicochemically characterized by Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and micro-Raman spectroscopy (µRaman). Embryos were exposed to nominal concentrations ranging from 0.5 to 20 mg/L, and endpoints including survival, hatching rate, spontaneous movements, heart rate, morphology, and locomotor activity were assessed. PMMA exposure did not induce significant mortality or morphological abnormalities at any tested concentration. However, significant sublethal effects were observed, including accelerated hatching at 20 mg/L and increased heart rate across exposure groups, further supported by a positive concentration–response trend across vessel-level values, indicating altered developmental timing and cardiovascular function. These findings demonstrate that PMMA microplastics, despite low acute toxicity, can induce early physiological disturbances in a vertebrate model. The results highlight the importance of incorporating sensitive functional endpoints into hazard assessment frameworks and contribute to a more comprehensive evaluation of the environmental risks associated with microplastics traditionally considered to have low intrinsic reactivity. Full article

The uniformity of polymer matrices can strongly influence pattern retention during negative-tone development. In this study, two 3-arm star terpolymers, designated HTM Random and HTM Block, were synthesized via reversible addition–fragmentation chain transfer polymerization using simultaneous and sequential monomer-addition strategies, respectively. Both polymers were prepared using the same nominal feed ratio of 2-hydroxyethyl methacrylate, dicyclopentanyl methacrylate, and 2-methyl-2-adamantyl methacrylate. Although the two materials exhibited controlled molecular weight distributions and similar FT-IR spectral changes after ultraviolet exposure and post-exposure baking, differences were observed in their chain-packing characteristics, thermal behavior, and developed pattern morphology. The two materials exhibited comparable initial thermal stability but distinct multistep degradation profiles and glass-transition behavior. In contrast, the simultaneous-feed material showed more clearly retained and spatially uniform patterns under the tested development conditions. These results indicate that the materials produced by the two monomer-addition strategies exhibited differences in thermal response and development behavior under the investigated conditions. Full article

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

Traditional brick masonry buildings in China are commonly constructed using fired clay grey bricks bonded with glutinous rice mortar, forming a unique historical masonry system with significant cultural value. During long-term service, these structures are vulnerable to environmental deterioration, material aging, and seismic actions, resulting in cracking, deformation, and degradation of structural integrity and load-carrying capacity. Carbon fiber-reinforced polymer (CFRP) sheets have been increasingly applied for strengthening masonry structures due to their high strength-to-weight ratio, corrosion resistance, and convenient installation. However, most existing studies on Fiber-reinforced polymer (FRP)–masonry interfaces have focused on conventional masonry systems, while the interfacial bond behavior and load-transfer characteristics between CFRP sheets and traditional grey brick masonry bonded with glutinous rice mortar remain insufficiently investigated. This study investigates the interfacial bond behavior of CFRP-strengthened traditional grey brick masonry through combined experimental testing and numerical analysis. First, uniaxial compression tests were conducted to determine the mechanical properties of glutinous rice mortar and fired clay grey bricks. Subsequently, double-shear tests considering different CFRP bond widths, bond lengths, and interface integrity conditions were performed to characterize the failure modes, force–displacement responses, and interfacial load-carrying behavior. The effects of interface geometric and integrity conditions were considered to evaluate the load-transfer characteristics of the strengthened interface. Based on the experimental results, a finite element model considering interface behavior was established and verified through comparison with the experimental results, which was subsequently employed to investigate the influence of bond width on interfacial stress transfer behavior beyond the experimental conditions. The results show that interfacial debonding accompanied by near-surface masonry damage dominates the failure process of CFRP–glutinous rice mortar masonry interfaces. Increasing the CFRP bond width enhances the interfacial load-carrying capacity and initial stiffness, while the ultimate capacity exhibits an approximately linear relationship with bond width within the investigated range. Numerical analyses further demonstrate that increasing bond width expands the effective load-transfer region, redistributes interfacial stresses, and delays stiffness degradation. These findings improve the understanding of interfacial bond behavior and load-transfer characteristics in CFRP-strengthened traditional masonry systems and provide references for the design and performance evaluation of strengthening applications in historic masonry structures. Full article

Hydrogel-and-nanomaterial-integrated wearable biosensor networks are promising platforms for real-time biomedical monitoring because they combine soft biointerfaces, sensitive signal transduction, and wireless data connectivity. Hydrogels provide tissue-like softness, hydration, adhesion, permeability, and biocompatibility, whereas nanomaterials such as graphene, carbon nanotubes, MXenes, metallic nanoparticles, and conductive polymers enhance conductivity, electrochemical activity, optical responsiveness, mechanical durability, and signal amplification. This review summarizes recent advances in hydrogel-and-nanomaterial-integrated wearable biosensors, ranging from soft material interfaces and stand-alone sensing devices to wireless wearable nodes, IoT-connected platforms, and emerging closed-loop sensor–actuator systems. Because these platforms differ substantially in their level of integration and validation, this review distinguishes enabling material and device concepts from fully connected or closed-loop systems. The distinctive contribution of this review is a materials-to-systems, evidence-graded framework that links hydrogel and nanomaterial interface design with sensing mechanisms, wearable sensor-node integration, wireless and IoT connectivity, and closed-loop actuation while distinguishing device-level proof of concept from clinically validated performance. We discuss functional hydrogel design, nanomaterial-based conductive networks, hybrid hydrogel–nanomaterial structures, and key requirements for skin compatibility, adhesion, stretchability, and long-term stability. Major sensing mechanisms and biomedical targets are reviewed, including electrochemical and optical biosensing, mechanical and physiological signal sensing, and sweat biomarker monitoring. We further highlight system-level integration strategies involving wearable sensor nodes, wireless communication, smartphone and cloud connectivity, data processing, power management, security, and reliability. Representative biomedical applications are summarized, including sweat-based metabolic monitoring, smart wound monitoring, hydrogel-based wound dressings, cardiovascular and respiratory monitoring, and motion sensing. Finally, current technical and translational challenges are discussed with emphasis on the distinction between analytical sensing performance, physiological correlation, and clinical validation. Disease-management and closed-loop healthcare applications are discussed as emerging directions that require appropriate human studies, reference-method comparison, agreement analysis, long-term monitoring, and safety validation before clinical implementation. Full article