Search Results (894)

Organic dyes are critical components in industries ranging from textiles, plastics, and paper to food, cosmetics, and pharmaceuticals. However, their widespread use leads to significant environmental pollution. Consequently, developing efficient methods to treat dye wastewater is urgently needed. In this work, a high-performance composite membrane was developed with a poly(dibenzo-18-crown-6) covalent organic polymer (COP) interlayer. The chemical structure of the COP was verified by FT-IR, and BET analysis indicated that the as-synthesized material possesses a predominantly mesoporous structure with a minor microporous contribution. Subsequently, the membrane was fabricated by depositing a COP colloid on a nylon-66 support via vacuum filtration, followed by the formation of a dense polyamide (PA) active layer through interfacial polymerization (IP) between amine and acyl chloride monomers. Systematic evaluation of dye separation performance using a cross-flow filtration setup identified optimal operating conditions. Under these conditions, the membrane demonstrated effective molecular sieving behavior, achieving both high dye rejection and favorable solvent permeability. In long-term stability tests, the membrane maintained a rejection rate of over 99% for Congo red over 48 h, while sustaining a water flux of 103.2 L m⁻² h⁻¹ bar⁻¹ (LMH/bar). Furthermore, the membrane exhibited promising potential for dye desalination applications, achieving a high Congo red/potassium chloride separation selectivity of 186.8 with a flux of 138.2 LMH/bar. This study confirms that the poly(dibenzo-18-crown-6)-based composite membrane is a reliable and efficient material for molecular separation in wastewater treatment. Full article

Fiber-reinforced rubber composites (FRRC) are widely employed in critical industries, such as the automotive, aerospace, and construction protection industries, due to their excellent deformation resistance and superior mechanical properties. Polyester (PET) fiber, with its outstanding dimensional stability and cost-effectiveness, has increasingly replaced nylon as the primary reinforcement in radial tires. However, the lack of polar groups on PET surfaces results in poor interfacial adhesion with rubber matrices, limiting composite performance. Traditional resorcinol–formaldehyde–latex (RFL) dipping systems enhance adhesion but raise environmental and health concerns due to the release of hazardous substances. This study develops a novel eco-friendly γ-Aminopropyltriethoxysilane (KH550)–glycerol triglycidyl ether–sorbitol glycidyl ether–2-Ethyl-4-methylimidazole–latex (KG-SML) dipping system to enhance PET–rubber interfacial adhesion. At an optimal KH550 dosage of 2 phr, the 180° peel force and H pull-out force reached maximum values of 23.5 N/piece and 109.0 N, respectively, significantly surpassing the performance of the conventional RFL system. The KG-SML system offers an effective and sustainable alternative to RFL, with enhanced interfacial performance and less environmental impact. Full article

Plastic pollution, particularly in marine environments, has become a major global concern; therefore, monitoring and controlling these contaminants is essential to safeguard ecosystem integrity and human health. This study evaluates the ability of Posidonia oceanica spheroids to incorporate and retain plastic debris, with a particular focus on microplastics (MPs). A total of 1300 spheroids were collected along the Latium coast (Central Italy); among these, 454 (34.9%) contained plastic debris, with an average of 3.1 items per spheroid. Overall, 1415 plastic items were extracted and identified. Based on size classification, 48.7% were microplastics, 29.6% mesoplastics, and 21.9% macroplastics. Plastic items mainly consisted of filaments (40.9 ± 12.6%) and fibers (21.5 ± 5.2%). Eleven different colors were recorded, with white (28.8 ± 9.1%), transparent (13.4 ± 6.0%), and black (11.1 ± 6.8%) being the most frequent. A strong correlation was observed between the number of plastic items contained in the spheroids and proximity to wastewater treatment plants, which are known sources of synthetic fibers. Fourier transform infrared spectroscopy (FTIR) identified a total of 15 polymer materials, with nylon (18.2 ± 11.0%) and polyethylene terephthalate (PET; 17.3 ± 7.2%) being the most abundant. Structural alterations observed in FTIR spectra, together with carbonyl index values, indicate that most MPs are of secondary origin, resulting from prolonged environmental degradation. These results demonstrate that P. oceanica spheroids effectively promote plastic trapping and highlight their potential as a simple and cost-effective monitoring tool for marine plastic pollution. Full article

Additive manufacturing has been widely adopted in industry as an alternative to traditional manufacturing processes for complex component production. In fact, a diverse range of materials, particularly polymers, can be processed using 3D printing for biomechanical applications (e.g., prosthetics). However, in-depth evaluation of these materials is necessary to determine their suitability for demanding applications, such as those involving cyclic loading. Following previous work that studied Polylactic Acid (PLA) and Polyethylene Terephthalate Glycol-modified (PETG) under experimental fatigue testing, this study examines the fatigue behaviour of other current 3D-printed polymeric materials, namely Acrylonitrile Styrene Acrylate (ASA), Polycarbonate (PC), Polyamide 12 (Nylon 12), and Polycarbonate–Acrylonitrile Butadiene Styrene (blend) (PC-ABS), for which fatigue data remain limited or even non-existent. The findings revealed performance differences on Tensile Strength (σ_R), Young’s Modulus and Ultimate Strain among tensile specimens made from these materials and characterised S-N curves for both high-cycle (HCF) and low-cycle (LCF) fatigue regimes at room temperature, with a tensile load ratio (R = 0.05). These results establish relationships among fatigue limit and quasi-static mechanical properties, namely 25% × σ_r for ASA (8 MPa), 7% × σ_r for PC (3.6 MPa), 17% × σ_r for Nylon 12 (7.4 MPa), and 15% × σ_r for PC-ABS (4.7 MPa), as well as between mechanical properties and preliminary potential biomechanical applications. Main conclusions were further supported by micro-computed tomography (micro-CT), which revealed levels of porosity in between 4% and 11%, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Full article

With the industry development of sea cucumber Apostichopus japonicus aquaculture, the indoor high cost and low survival rate have become serious problems. Therefore, it is necessary to optimize substrate selection for seedling protection in outdoor pond net cages. This study explores the succession of periphyton on the different substrate surface types, including a curvimurate net (CU), nylon mesh (NM), and ground cages (including a ground cage net (CN) and ground cage plate (CP)), and their effects on the seedling protection of sea cucumbers. In addition, we monitored the substrates’ dry weight, chlorophyll-a, and the community composition of substrates, alongside seedling growth, yield, and survival rate. The results show that a total of 7 phyla, 23 genera, and 31 species were detected on the substrates, with diatoms dominating (19 species) and Chlorophyta (4 species) being the main species. The CU had the highest total number of alga species attached, significantly higher than the other substrates in week 13 (p < 0.05). In week 9, the diatom density dropped to its lowest point, and, after September, it rose with the decrease in water temperature. In terms of dry weight with and without ash, CP increased rapidly in the early stage, with NM, CU, and CP being significantly higher than CN in week 13 (p < 0.05). The chlorophyll-a content showed a decreasing–increasing–decreasing trend, with CU reaching 3.62 ± 0.48 μg/cm² in the 13th week, significantly higher than other substrates (p < 0.05). Finally, the A. japonicus survival rate and yield in the CU group at week 12 were significantly higher than those in the NM and ground cage groups (p < 0.05). At week 17, the average weight, yield, and survival rate in the CU group were still optimal, with the yield 5.76 times that in the initial dosage. These results suggest that the CU has a suitable mesh size, has good permeability, and may stably support sediment, which is conducive to the growth of benthic diatoms. In addition, it can provide sufficient natural feed and a good habitat environment and is the preferred substrate for A. japonicus seedling protection in outdoor pond net cages. Full article

High-performance nylon 6,6 webbings used in critical applications degrade under solar exposure, necessitating reliable methods to assess their residual strength non-destructively. This study investigates the feasibility of using instrumental color change as a predictive indicator for the loss of breaking strength. Four colors of nylon 6,6 webbings were subjected to accelerated xenon-arc solar weathering for up to 15 days. The resulting color change was quantified using both the CIELab and CIEDE2000 formulas, and residual breaking strength was measured following ASTM D6775. A regression analysis was performed to correlate these properties. The results demonstrate that a strong predictive relationship exists, but its efficacy is highly color-dependent. Webbing with high initial chroma, namely tan (R² = 0.889) and navy (R² = 0.817), showed a strong correlation between color change and strength loss. In contrast, the models for low-chroma black and white webbings were weak and unreliable. Furthermore, the simpler CIELab (ΔE*_ab) formula provided slightly more accurate predictions than the more complex CIEDE2000 (ΔE*₀₀) metric. It is concluded that colorimetry can be a viable non-destructive tool for predicting mechanical degradation, but its application is limited to specific high-chroma materials, precluding a universal model based entirely on colorimetry. Full article

Microplastics (MPs) have been attracting considerable interest in recent years due to their ubiquitous existence and accumulation within different systems and ecosystems. Moreover, their presence in electroplating baths involves a more serious challenge considering that the electroplating industry is progressing towards the electroplating of plastic materials. Contaminated baths can lead to surface defects, poor adhesion, corrosion, and inconsistent deposit thicknesses. Despite these issues, the interactions between pollutant MPs and heavy metal ions in electroplating environments are still underexplored. The present study aims to investigate the behavior of self-produced “Nylon PA” MPs dispersed in acid copper electroplating baths and their interactions with copper ions in solution. Scanning electron microscopy (SEM) reveals several surface defects in copper deposits caused by MPs in the bath. Additionally, cyclic voltammetry and chronoamperometry indicate significant changes in nucleation and growth mechanisms, with MPs showing suppressant-like effects on copper deposition. These results shed light on the impact of MPs on copper electrodeposition, emphasizing the urgent need for further research and mitigation strategies to address this emerging issue in the electroplating industry. Full article

The evolution of tennis equipment is fundamentally linked to advances in materials science and engineering, which have enabled enhanced player performance through optimised racquet and string designs. This review comprehensively examines the critical role of modern composite materials, manufacturing methods, and string technologies in tennis equipment, focusing on how these elements influence mechanical performance and player experience. It first explores the contributions of matrix and reinforcing materials, particularly carbon fibre and aramid composites, to racquet stiffness, strength, and vibration damping. Next, it details advanced manufacturing techniques such as prepreg layup, autoclave curing, and hollow moulding, which enable precise control over mechanical properties and quality assurance. This paper further evaluates various string materials including natural gut, Kevlar, polyester, nylon, and emerging hybrid setups, analysing their mechanical characteristics, tension maintenance, and impact on ball response and player comfort. Special attention is given to the interaction between design choices and playing conditions, such as court surfaces and player sensitivity, underscoring the complex interplay between equipment mechanics and gameplay dynamics. Through an interdisciplinary lens, this paper synthesises current scientific knowledge and experimental findings, providing a critical foundation for optimising tennis equipment design. By integrating materials science with practical application, this paper provides a comprehensive understanding of tennis equipment design, identifying gaps in current research and offering insights to guide future innovation for manufacturers, coaches, and players. Full article

This work presents results of nylon-based composites used in additive manufacturing (AM) subjected to 24, 48, 96, 168, 336, and 504 h of continuous exposure to UV and 50% humidity. Sample coupons were built on a Markforged Two^® printer. To mimic UV exposure, samples were exposed to 253 nm UV light (UV–C), whereas for humidity, samples were placed at 50% relative humidity and 22 °C in a bi-distilled water atmosphere. The effects of said exposure were measured in tensile, Charpy impact energy, mass absorption, and Shore hardness D tests. Nylon gained 5.6% ± 0.48 mass after 504 h. For Charpy, absorbed energy went down from 0.463 J/mm² to 0.28 J/mm² at 504 h of humidity exposure. For Shore D, the variation goes from 59.1 ± 0.82 for zero exposure to 66.8 ± 2.5 at 504 h of UV exposure. Conversely, UV exposure induced an increase in Young’s modulus and Shore hardness, while significantly reducing impact energy to 0.32 J/mm², indicating embrittlement confirmed by SEM analysis. FTIR analysis revealed hydrolytic degradation under humidity and photo-oxidative degradation under UV, affecting N–H and C=O bonds. These findings allow a designer to project the residual mechanical properties of a component up to its last day of service. Full article

Preterm infants in neonatal intensive care units (NICUs) experience impaired neurodevelopment and dysregulated stress responses, partly due to a lack of tactile stimulation. Although massage therapy offers proven therapeutic benefits by stimulating C-tactile afferents through (gentle) dynamic touch, existing methods are limited by clinical staff variability and resource constraints. This work presents a compact soft-pneumatic actuator array (SPAA) utilizing four nylon–TPU actuators (modules) connected in series or in parallel to perform a sequential actuation; this array is designed to deliver safe, shear-free, and massage-like normal compression tailored for preterm infants. Actuator performance was characterized using a load-cell and a pressure sensor under different preloads (10–30 g), establishing operating internal pressures of 20–50 kPa, which produced target force ranges between 0.1 and 0.3 N. Two SPAA architectures were evaluated: (i) parallel manifold with branch resistances and (ii) series chain with graded outlet resistances, using passive fluidic sequencing for controlled activation. The series configuration achieved repeatable sequential actuation with programmable delays, essential for mimicking therapeutic massage patterns. These results demonstrate that passive soft-pneumatic sequencing can reliably deliver dynamic tactile stimuli within neurophysiological and safety constraints, laying the groundwork for standardized, automated neonatal massage therapy in NICUs. Full article

1,5-Pentanediamine (PDA) is an important monomer for the synthesis of nylon materials. However, its microbial production from glucose is severely limited by product cytotoxicity, which slows the metabolism of both precursor lysine and glucose uptake. To overcome this limitation, a PDA-responsive dynamic regulatory switch (PDRS) was constructed using the transcriptional repressor CgmR and the P_cgmA promoter. By replacing promoters and ribosome-binding sites, the response window of the PDRS was optimized to a PDA concentration range of 38.9–87 g/L. Based on this system, the PDRS was employed to enhance lysine biosynthesis and glucose uptake. Following fermentation optimization, the optimal strain Corynebacterium glutamicum YY3.6 produced 105.5 g/L PDA within 36 h, achieving a PDA productivity of 2.93 g/L/h and a yield of 0.36 g/g glucose. Collectively, these results provide an effective strategy for the microbial production of PDA from glucose. Full article

The article presents a comparative analysis of mechanical properties of M8 threaded joints produced using three different methods, in rectangular nylon (PA 12) specimens manufactured in SLS technology. Threaded holes in specimens were made by direct thread printing (specimens marked PT), thread reinforcement with Helicoil inserts (HT), and the use of heat-set inserts (IT). The specimens were subjected to a tensile testing at a constant displacement rate of 2 mm/min. The maximum force and the displacement at failure were recorded. The results indicated that the lowest load-bearing capacity F_MF was observed in the printed thread specimens, with an average value of 3.41 kN. The use of heat-set inserts increased F_MF to 3.83 kN, representing a 12% improvement. The highest load-bearing capacity was achieved in specimens reinforced with Helicoil inserts, which enhanced joint strength by 40% compared to printed thread specimens, reaching an average F_MF of 4.78 kN. In all cases, failure occurred due to the thread or insert pull-out from the specimen material. Studies have shown that the use of metal inserts significantly enhances the strength of threaded joints in SLS-printed PA12 components. Helicoil inserts provide the highest F_MF load capacity, while heat-set inserts offer better technological advantages. Although printed threads are easier to manufacture, their applicability is limited to larger thread sizes and lower mechanical loads. Full article

The selective hydrogenation of phenol to cyclohexanone is a pivotal reaction for producing nylon precursors. Conventional Pd/C catalysts, however, suffer from weak metal–support interactions, leading to size heterogeneity and agglomeration of Pd nanoparticles, which degrades their activity and stability. Herein, we report a facile argon plasma treatment to engineer rich defects on an activated carbon (AC) support, resulting in a highly dispersed and stable catalyst (denoted as PL-Pd@AC_Ar). Characterization results indicate that the abundant carbon defects in PL-Pd@AC_Ar enhance the anchoring of Pd precursors, ensure the uniform dispersion of Pd nanoparticles, and effectively modulate their electronic structure. Consequently, the plasma-enabled PL-Pd@AC_Ar catalyst achieves 99.9% phenol conversion with 97% selectivity to cyclohexanone at a mild temperature of 70 °C and maintains exceptional stability over six consecutive cycles. This work provides a robust and efficient strategy for the surface engineering of carbon supports to design high-performance hydrogenation catalysts. Full article

Background: Nylon-based removable partial dentures, such as Valplast^® (Valplast International Corp, Westbury NY, USA), have been proposed as a valuable alternative to acrylic resin prostheses, particularly following oral surgical extractions and in patients with suspected methacrylate hypersensitivity. This review aimed to evaluate the clinical indications guiding the use of nylon-based prostheses after oral surgical extractions and to investigate their prevalence in patients with documented acrylic allergies. Methods: Following PRISMA 2020 guidelines, a comprehensive search was conducted in six databases (PubMed, Scopus, Embase, Google Scholar, LILACS, and Cochrane Library) for studies published between 2015 and 2025. Eligible studies were critically appraised using the Joanna Briggs Institute (IBI) tools. Results: Nine studies met the inclusion criteria, all of which were low-level evidence (six case reports and three case series), comprising a total of 11 patients (mean age 43 years). Nylon-based prostheses were used in both maxillary and mandibular arches, with rehabilitation motivated by esthetic and functional reasons. Outcomes were generally favorable, with patients reporting satisfaction in terms of comfort, function, and esthetics. Conclusions: Current evidence supporting the use of nylon-based removable partial dentures remains extremely limited and is based exclusively on case reports and small case series. While this type of prostheses represents a viable post-surgical rehabilitation option, primarily chosen for esthetic and functional benefits, evidence on their use in patients with documented acrylic hypersensitivity remains lacking. The low quality and limited number of studies highlight the need for prospective, controlled, and long-term research to clarify the role of nylon prostheses in post-surgical oral rehabilitation and to define their effectiveness in patients with material allergies. Full article

Background: The aim of this study was to evaluate and compare the bacterial colonization, cytotoxicity, immune response, and clinical parameters of three different suture materials: multifilament silk (Silk^®), monofilament nylon (Daclon^®), and expanded polytetrafluoroethylene monofilament (PTFE^®), in surgical extractions of impacted mandibular third molars. Methods: This randomized controlled clinical trial was conducted on twenty-one patients requiring surgical extraction of an impacted third mandibular molar. A bayonet-shaped flap was sutured using all three materials in each patient. Bacterial cell counting and qPCR were assessed for microbiological analysis. In vitro cytotoxicity was studied with the metabolic activity WST-1 assay. Inflammatory response was evaluated through histological analysis. Clinical parameters—healing, handling, slack, pain, swelling and trimus—were recorded. Statistical significance was set at p ≤ 0.05. Results: Monofilament sutures accumulated fewer bacteria and DNA copies than Silk^® (p < 0.05). The WST-1 assay revealed non-cytotoxic effects. Silk^® presented an immune response with lymphocyte-like cells. The highest values of pain and inflammation were reached at 48 h, with a significant correlation between them (p < 0.05). Silk and nylon were more manageable than PTFE (p < 0.001), and nylon had less slack (p < 0.001). Conclusions: Silk showed the poorest microbiological and histological performance, with higher levels of bacterial colonization and a more pronounced inflammatory response compared to the other types of suture. Clinically, it offered better handling than PTFE (PTFE^®), comparable to nylon (Daclon^®), but it exhibited greater slack, which could prove less favorable for wound stability. None of the sutures showed in vitro cytotoxicity. Monofilament sutures, particularly nylon (Daclon^®), showed better outcomes, acceptable handling, less bacterial colonization, and a milder inflammatory response. Full article