Search Results (16,636)

This comprehensive review systematically examines the fundamental and contemporary concepts underlying the Toms effect—the phenomenon of turbulent drag reduction (DR) induced by the addition of minute concentrations of high-molecular-weight linear polymers to turbulent flows. The evolution of scientific understanding is traced from the classical studies of the mid-twentieth century to contemporary machine-learning-based approaches. The influence of four key parameters is examined in detail: the dimensionless solvent viscosity ratio $\beta$, Reynolds number $Re$, conformational chain length $L_c/MW$, and macromolecular relaxation time $\lambda$. Polymer concentration $C$ is treated as an independent control variable through which the values of these four parameters are partially determined. The principal physical mechanisms at the molecular and hydrodynamic levels are described. The capabilities of numerical modeling approaches (DNS, LES, and RANS) are critically reviewed, along with promising directions for the application of artificial intelligence. Finally, practical guidelines are proposed for validating and interpreting experimental and numerical drag-reduction data over a broad range of hydrodynamic conditions. Full article

Membrane separation technology is extensively used in water treatment. However, during long-term operation, biofouling caused by bacteria and other microorganisms significantly limits the service life of membranes. Introducing antibacterial nanomaterials onto the membrane surface or into the internal structure is an effective way to combat biofouling. This review systematically summarizes recent progress in antibacterial membranes modified with different nanomaterials. First, we classify antibacterial nanomaterials by dimensionality and highlight their physicochemical properties and effects on overall membrane performance. Furthermore, we summarize the advantages, disadvantages, and applicability of three antibacterial nanomaterial modification strategies for membranes, including surface coating, grafting, and blending. Subsequently, we analyze in depth the main antibacterial mechanisms that enhance membrane performance, including metal ion release, reactive oxygen species oxidation, physical contact disruption, and anti-adhesion, as well as their synergistic effects. Finally, we critically evaluate the remaining challenges, such as interfacial compatibility between nanomaterials and polymers, controlled release of metal ions, and environmental safety. This review provides a reference for the rational design of high-performance antibacterial membranes. Full article

In this paper, we report a metal-driven structural tuning strategy with the L-histidine (His) ligand to modulate peroxidase-like nanozyme performance. Although the His coordinates with gold(III) ions to form an extended helical coordination polymer, its interaction with Cu(II) ions results in quantum-confined, ultrasmall nanoclusters. Based on the optical, structural, and surface analysis, the blue-emitting cores are stabilized by His ligands through imidazole nitrogen coordination, consistent with a Cu-centered coordination environment involved in the observed catalytic activity. According to the catalytic measurements, the His-Cu clusters outperformed the His-Au coordination polymer reference system. Steady-state kinetic modeling and 3D profiling revealed a pronounced shift in the pH optimum: low-valent Cu-containing His-Cu NCs enable efficient peroxide-dependent catalysis under nearly neutral conditions (pH 7.4), whereas His-Au CP exhibits its maximum activity under acidic conditions. Based on these findings, this work highlights nanoscale engineering for tailor-made biomimetic applications. Full article

Polysaccharide-based organic−inorganic hybrid carriers combine renewable polymer matrices with inorganic phases that can modify mechanical integrity, swelling, barrier performance, payload retention, and release behavior. This review critically evaluates alginate as a reference matrix together with chitosan, cellulose/nanocellulose, starch/maltodextrin, pectin, carrageenan, and related polysaccharides, focusing on how matrix chemistry, inorganic-phase properties, interfacial interactions, and fabrication route govern encapsulation efficiency, loading, structural stability, swelling, mechanical and barrier properties, storage retention, and release kinetics. Silica and mesoporous silica, clays and halloysite, layered double hydroxides (LDHs), metal oxides, hydroxyapatite, magnetic particles, and metal−organic frameworks are compared according to their reservoir, reinforcing, diffusion-controlling, responsive, and safety-related functions. Representative quantitative findings illustrate the importance of hybrid architecture; for example, incorporation of LDHs into an alginate matrix reduced erythropoietin release after 108 h from 86% to 24% while increasing mechanical performance by approximately 5–30-fold. In this review, particular attention is given to volatile and bioactive compounds, for which storage retention, oxidation stability, headspace behavior, and application-relevant release are as important as initial encapsulation efficiency. Key challenges, such as long-term stability, standardization of release studies, scalability, safety assessment, and performance in real formulations, are also discussed, together with future directions for sustainable, application-specific hybrid carrier systems. Overall, the review provides a structure−property-application framework for selecting matrix−filler-processing combinations for controlled-release systems. Full article

Background: Plants have been traditionally used for centuries to treat wounds and, over time, have been tested for their healing properties. There is a constant search for new natural resources that could be used to develop various topical wound care products. Methods: A comprehensive search of the literature was conducted in PubMed/MEDLINE, Scopus, and Web of Science databases (2022–2026) in accordance with the PRISMA 2020 guidelines. Included studies focused on current in vitro and in vivo research on hydrogels containing plant extracts from the Asteraceae and Lamiaceae families and their potential application in wound healing and skin regeneration. Results: An analysis of 24 included studies confirms that both families include interesting and valuable plants with antioxidant, antimicrobial and anti-inflammatory properties; these plants also influence collagen deposition, fibroblast proliferation, and epithelialization, and reduce the risk of infection, thereby contributing to faster wound healing. The most frequently tested phytoextract in this respect was Calendula officinalis (Asteraceae) incorporated into a hydrogel. A variety of materials, including natural, semi-synthetic, and synthetic polymers, as well as hybrid matrix, but also diverse formulation strategies, from simple solutions to more advanced and modern methods, have been used to produce hydrogels. Conclusions: This systematic review summarizes the current evidence, highlights directions and possibilities for the use of phytoextract-based hydrogels, and discusses limitations and future perspectives in the development of effective externally applied formulations to support wound healing. Full article

Background/Objectives: Matrix pellet formulations enable homogeneous incorporation of the active ingredient and advanced control of release depending on the excipients added. The aim of this study was to develop, characterize, and assess the drug release profiles of microcrystalline cellulose (MCC) and isomalt-based matrix pellets with direct drug incorporation, advancing beyond the earlier concept of isomalt as a mere inert core with layered drug application, under simulated physiological conditions in vitro. Methods: Matrix pellets with varying MCC–isomalt ratios (90:10, 70:30, and 50:50) were produced by extrusion/spheronization and subsequently coated with film-forming polymers. Dissolution experiments were performed under varying osmolarity to characterize release profiles. The experimental design data were statistically evaluated. Results: The extrusion/spheronization technique yielded uniform, robust matrix pellets with acceptable sphericity and mechanical integrity, even at high isomalt levels. Release from coated pellets was significantly influenced by the polymer coating and osmolarity of the dissolution medium. However, with increasing isomalt content in the matrix, the dependence of drug release kinetics on medium osmolarity was substantially reduced. Conclusions: The production of MCC–isomalt matrix pellets in which isomalt acts as a functional matrix component reduced the effect of osmolarity of dissolution medium on the release of ibuprofen sodium salt in in vitro experiments. Full article

Non-mechanical beam steering technology based on liquid crystal optical switches and liquid crystal polarization gratings holds significant application prospects in fields such as laser communication, radar detection, and optical information processing. Traditional nematic liquid crystal optical switches exhibit slow response speeds, whereas novel ferroelectric liquid crystal optical switches, despite their fast response, are hampered in engineering applications by complex fabrication processes, the large number of devices required for cascading, and substantial module thickness. To address these issues, this paper proposes and demonstrates a fast non-mechanical beam steering scheme by cascading a stressed polymer network liquid crystal (SPNLC) optical switch with a liquid crystal polarization grating. The SPNLC is fabricated by mechanically shearing a polymerized liquid crystal–polymer composite, enabling sub-millisecond response and continuous linear phase modulation without the need for an alignment layer. A 30-μm-thick SPNLC half-wave plate was prepared, which introduces a phase retardation of 3.6 μm under a driving voltage of 300 V, and the rise time and fall time are measured to be approximately 526 μs and 560 μs at a driving voltage of 20 V with a 1 kHz square wave, and 470 μs and 538 μs at 27 V under the same waveform conditions. Cascaded with a passive polarization grating, the waveplate enables fast electrical switching of the beam between the ±1st diffraction orders. Furthermore, a two-dimensional multi-angle beam deflector was constructed based on a supra-binary cascade scheme. Experimental results confirm that the system possesses sub-millisecond response, large phase retardation, continuous tunability, and an alignment-layer-free fabrication process, demonstrating its feasibility for large-range fast beam scanning. Full article

Absorbent pads are important materials for regulating exudate and local microenvironments in the packaging of high-moisture perishable foods. However, conventional absorbent pads often suffer from limited functionality, insufficient liquid retention, and a lack of active responsiveness. Hydrogels and aerogels, with tunable three-dimensional polymer networks, provide an important material basis for the design of new functional absorbent pads. This review focuses on the relationships among structure, function, and application, and compares hydrogels and aerogels in terms of network composition, crosslinking strategies, water absorption and retention mechanisms, and active compound loading and release behaviors. Structural design strategies, including multilayer structures, Janus structures, gradient pore structures, and micro/nano-reinforcement, are also summarized. On this basis, recent applications of hydrogel- and aerogel-based absorbent pads in the packaging of meat, aquatic products, fruits, vegetables, and edible fungi are discussed. Finally, the key challenges facing gel-based absorbent pads are analyzed, including adaptation to real food systems, release regulation, food-contact safety, and industrial-scale production. This review establishes a structure–function–application framework for gel-based absorbent pads and offers insights for designing sustainable active and intelligent food packaging. Full article

Environmental stress cracking (ESC) severely limits the long-term reliability and engineering application of polycarbonate (PC)-based materials. In this work, a universal strategy is proposed to enhance the ESC resistance of PC by introducing crack-termination sites, enabling efficient suppression of crack propagation without compromising the intrinsic mechanical properties of PC. A quantitative evaluation framework based on a constant-strain method is established, and the critical strain rate (η) is defined as a key parameter for assessing ESC behavior under chemo-mechanical coupling. Systematic experiments reveal that chain entanglements, rubbery phases, and crystalline region can effectively increase η value of PC-based materials, demonstrating their superior crack-termination efficiency. Notably, the β-crystalline phase in PBT and microcrystalline domains induced by ethylene–acrylate copolymer tougheners are identified as the most efficient crack-termination structures, providing continuous energy-dissipation pathways and effectively halting crack propagation. This work not only establishes a practical and quantitative approach for evaluating ESC performance but also provides an integrated material-modification strategy. The proposed concept of crack-termination sites offers new insight into the development of high mechanical performance and ESC resistance PC-based polymer systems for advanced industrial applications. Full article

There is an increasing demand for ultrasound imaging technologies, particularly wearable and portable systems, for continuous physiological monitoring applications. Although some recent flexible ultrasound devices have adopted polymer encapsulations, typical rigid transducer designs still include metal housings and costly electrodes, contributing to increased device weight and fabrication cost. To address these limitations, we developed an aluminum-electrode/3D-printed polymer-housing ultrasound transducer (APUT) utilizing a polyvinylidene fluoride piezoelectric film. Compared to a gold-electrode/metal-housing ultrasound transducer, the APUT material costs and total weight were approximately 66% and 86% lower, respectively. Acoustic evaluation revealed a center frequency of 24.5 MHz and a fractional bandwidth of 60.9%, with axial and lateral resolutions of 51 and 152 μm, respectively. Furthermore, during a 3-h pulsed operation test, the APUT exhibited an initial increase in capacitance followed by a relatively stable response, with no progressive surface-temperature increase detected within the accuracy of the measurement method. Finally, successful ex vivo imaging of chicken breast tissue confirms the APUT’s biomedical applicability, highlighting its potential as a wearable, portable, and disposable ultrasound platform. Full article

This study presents an electrothermal coating approach for synthesizing cell-imprinted polymers (CIPs) on metallic microwires through localized resistive heating-induced polymerization. Imprinted polymers (IPs) are robust, cost-effective synthetic affinity materials widely used in sensing applications. However, conventional fabrication methods, including bulk and suspension polymerization, often lack spatial control, producing non-specific polymerization, heterogeneous coatings, and reduced sensor reproducibility. Electrochemical polymerization provides improved spatial control but requires specialized instrumentation and restricts monomer selection. Here, applying direct current (DC) to metallic microwires immersed in a prepolymer solution generated localized Joule heating, enabling controlled in situ polymerization and uniform coatings while minimizing undesired bulk polymerization. By optimizing the applied current and polymerization time, CIP coatings with tunable thicknesses were fabricated on gold-coated microwires. Under optimized conditions, ~6 µm thick coatings were imprinted using Salmonella templates. Scanning electron microscopy revealed bacteria-shaped cavities consistent with template removal and the formation of imprinted cavities. Rebinding experiments demonstrated enhanced bacterial capture, with CIP-coated microwires achieving ~70% capture efficiency, compared to 22% for bare microwires and 33% for non-imprinted polymer (NIP) controls. These results support the effectiveness of the proposed method for localized polymerization and demonstrate the enhanced capture of the template species by CIP-coated microwires relative to bare microwires and NIP-coated controls. Full article

The rapid expansion of fiber-reinforced polymers (FRPs) in wind energy, transportation, and aerospace is generating increasing amounts of accompanied waste, making effective valorization essential to a circular economy. This review compares FRP recovery technologies in terms of recovered-fiber quality, operating conditions, post-treatment, environmental impacts, and industrial applicability. Then, it also examines direct reuse, FRP remanufacturing, and reuse in cementitious composites. Quantitative synthesis indicates that high-quality recycled carbon fibers (rCFs) generally retain more than 90% of their original strength, whereas mechanically recovered glass fibers (rGFs) typically retain approximately 70–90%. The preferred pathway depends on the intrinsic value, damage state, morphology, and residual properties. Components with sufficient residual capacity should be directly reused; high-quality fibers are better suited to polymer remanufacturing; and heterogeneous or lower-grade glass-FRP (GFRP) fractions are more compatible with cementitious applications, where mechanically recycled GFRP can provide interfacial bond strengths comparable to conventional engineering macrofibers. Future research should establish quantitative links among recovered material quality, processing, interfacial behavior, and end-use performance, while adopting consistent environmental and economic assessment boundaries. A graded utilization framework is therefore required to support both large-scale and value-added reuse of FRP waste. Full article

Electric aviation and unmanned aerial vehicles (UAVs) depend on lightweight composites to preserve payload and range, yet mass reduction, recycled content, or bio-based content alone does not establish component suitability. Candidate systems must also satisfy coupled structural, thermal, fire, electrical, manufacturing, durability, repair, and circularity requirements. This structured critical narrative review evaluates thermoplastic carbon-fibre-reinforced polymer (CFRP) systems, recycled-carbon-fibre composites, natural-fibre systems, bio-based and recyclable matrices, hybrid architectures, and multifunctional composites using a component-specific framework based on source role, evidence maturity, test comparability, and failure consequence. The framework links processing and chemistry to defects, retained performance, repair and recovery, and the evidence required for defined aircraft and UAV components. Thermoplastic CFRP provides the strongest near-term pathway for secondary and semi-structural components, although weld durability, impact tolerance, fire response, and process conformity remain system specific. Recycled-carbon-fibre and natural-fibre systems are most defensible for lower-consequence covers, fairings, housings, interiors, and UAV parts when feedstock variability, moisture, porosity, and fire performance are controlled. Battery enclosures, primary structures, rotor-support members, and structural-battery systems require representative coupled-hazard and component-scale evidence. The resulting adoption pathways are bounded by component and operating conditions, with manufacturing, durability, repair, recovery, and qualification evidence specified for each application. Full article

Organic solar cells (OSCs) and perovskite solar cells (PSCs) are emerging photovoltaic technologies owing to their high efficiency, low-cost processing, and diverse applications ranging from utility-scale power generation to small-scale electronics. A key advantage of OSCs and PSCs over traditional silicon-based solar cells is their solution-processability, which enables fabrication via cost-effective scalable printing technologies suitable for commercialization. In addition to organic and perovskite photoactive layers, other functional layers, including interfacial layers and electron and hole transport layers, can also be processed using solution-based printing techniques. However, the conventional architecture of these emerging photovoltaics relies on vacuum-based deposition processes for both oxide-based electrodes (e.g., indium tin oxide and fluorine tin oxide) and metallic top electrodes (e.g., Au, Ag, Cu, and Al), which contrasts with printing-based processing. The implementation of printing technologies for electrode fabrication is necessary to achieve low-cost production and flexible photovoltaic applications. Herein, we review printed electrodes—including metal electrodes, conductive polymers, and carbon-based materials—used to fabricate OSCs and PSCs. Full article

A series of molecularly imprinted polymers (MIPs) based on hydroxypropyl-β-cyclodextrin (HPCD) crosslinked with 1,6-hexamethylene diisocyanate (HMD) or toluene diisocyanate (TDI), as well as hybrid chitosan–HPCD polymers crosslinked with genipin, were synthesized using levofloxacin and fluorescein as template molecules. The structure and spatial organization of the obtained materials were characterized by FTIR spectroscopy, FTIR microscopy mapping, and ζ-potential measurements. The influence of pH, crosslinker content, and template structure on sorption performance was investigated. All MIPs exhibited maximum sorption at pH 3.0. The highest sorption capacity toward levofloxacin was achieved for the LV–Chit–HPCD–Genipin_MIP (74.8 mg/g), whereas the fluorescein-imprinted FL–HPCD–TDI_MIP (1:1) demonstrated the highest sorption capacity (135.5 mg/g) and selectivity coefficient (84.1). Dynamic column experiments confirmed efficient analyte extraction, reducing the analyte concentration by more than 90% after ten loading cycles. All synthesized MIPs exhibited excellent regenerability, with less than 3% loss of sorption efficiency after ten consecutive sorption–desorption cycles. The applicability of the developed sorbents to real matrices was demonstrated using milk and blood plasma samples after minimal sample preparation. Fluorescein extraction efficiencies reached 97.6% and 93.6% for milk and plasma, respectively. The obtained results demonstrate that HPCD-based MIPs combine high sorption capacity, exceptional selectivity, operational stability, and applicability to complex biological matrices, making them promising materials for selective sample preparation, analyte preconcentration, and controlled drug delivery systems. Full article