Fibers

16 pages, 4347 KB

Open AccessArticle

Comprehensive Evaluation of Wet-Spun Polyhydroxyalkanoate Fibres: Morphology, Crystallinity, and Thermal Properties

by Marta A. Teixeira, Inês Leite, Raquel Gonçalves, Helena Vilaça, Catarina Guise and Carla Silva

Fibers 2025, 13(8), 111; https://doi.org/10.3390/fib13080111 - 21 Aug 2025

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Abstract

In response to increasing environmental concerns, significant efforts have been made to reduce our reliance on fossil fuel-based plastics, driving the development of sustainable alternatives such as polyhydroxyalkanoates (PHAs). This study investigates the processing of various PHAs into fibres, focusing on their morphological, [...] Read more.

In response to increasing environmental concerns, significant efforts have been made to reduce our reliance on fossil fuel-based plastics, driving the development of sustainable alternatives such as polyhydroxyalkanoates (PHAs). This study investigates the processing of various PHAs into fibres, focusing on their morphological, thermal, and mechanical properties. Different PHAs were spun into fibres at a 15% (w/v) concentration using wet-spinning techniques. Among the PHAs studied, commercially available PHBHHx, used as a reference, exhibited spongy morphology in the fibres and demonstrated thermal vulnerability due to its rapid degradation. Blended fibres showed enhanced morphological and mechanical properties compared with neat fibres. In Fourier-transform infrared spectroscopy (FTIR), no differences were observed between the unprocessed polymers and the wet-spun polymeric fibres, indicating that the wet-spinning process did not affect the molecular structure of the polymers. Thermal and mechanical evaluations confirmed the miscibility between the polymers in the blends. Overall, these results highlight, for the first time, the successful production of wet-spun fibres from two modified P(3HB) variants, individually, in combination with each other, and in blends with the well-established commercial PHA, PHBHHx. However, this study also underscores the need to optimise feed rates to enhance fibre production efficiency and mechanical strength, thereby broadening their potential for various applications. Full article

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22 pages, 3241 KB

Open AccessArticle

Flexural Behavior of R-UHTCC and Recycled Concrete Composite Beams Reinforced with Steel Bars

by Dong Wei, Zuobiao Li, Zhiqiang Gu, Danying Gao, Lin Yang and Gang Chen

Fibers 2025, 13(8), 110; https://doi.org/10.3390/fib13080110 - 18 Aug 2025

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Abstract

To promote the application of recycled concrete in construction engineering, the flexural behavior of ultra-high toughness cement-based composite (UHTCC) materials and recycled concrete composite beams was investigated in this study. Recycled aggregates were used in the production of both recycled UHTCC (R-UHTCC) and [...] Read more.

To promote the application of recycled concrete in construction engineering, the flexural behavior of ultra-high toughness cement-based composite (UHTCC) materials and recycled concrete composite beams was investigated in this study. Recycled aggregates were used in the production of both recycled UHTCC (R-UHTCC) and recycled concrete. A total of 10 beams were manufactured and tested under four-point bending load. The primary design parameters included concrete strength grade, R-UHTCC layer height, stirrup spacing in the pure bending section, and tensile reinforcement ratio. The effects of these parameters on the failure mode, crack width, load-midspan deflection response, ductility, load-tensile reinforcement strain response, and flexural capacity of the beams are discussed. The results indicate that limiting the use of R-UHTCC to a specific height range within the tensile zone of the beams can yield superior flexural properties compared to using R-UHTCC across the full section. The R-UHTCC and recycled concrete composite beams demonstrated good crack resistance, load-deflection response, and ductility. Compared to the R-UHTCC layer height and stirrup spacing, the influences of concrete strength and tensile reinforcement ratio on the flexural behavior of the composite beams are more significant. The maximum increase in flexural capacity and ductility index was 18.8% and 67.3%, respectively, as the concrete strength grade increased from C30 to C70. The flexural capacity increased by 64.6% as the longitudinal reinforcement ratio increased from 0.258% to 3.68%. Furthermore, a stiffness calculation method based on the effective moment of inertia was proposed and validated through experimental results. The research findings provide a theoretical and design basis for the application of R-UHTCC and recycled concrete composite beams in engineering. Full article

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18 pages, 7353 KB

Open AccessArticle

Low-Carbon Concrete Reinforced with Waste Steel Rivet Fibers Utilizing Steel Slag Powder, and Processed Recycled Concrete Aggregate—Engineering Insights

by Dilan Dh. Awla, Bengin M. A. Herki and Aryan Far H. Sherwani

Fibers 2025, 13(8), 109; https://doi.org/10.3390/fib13080109 - 14 Aug 2025

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Abstract

The construction industry is a major source of environmental degradation as it is responsible for a significant share of global CO₂ emissions, especially from cement and aggregate consumption. This study fills the need for sustainable construction materials by developing and evaluating a [...] Read more.

The construction industry is a major source of environmental degradation as it is responsible for a significant share of global CO₂ emissions, especially from cement and aggregate consumption. This study fills the need for sustainable construction materials by developing and evaluating a low-carbon fiber-reinforced concrete (FRC) made of steel slag powder (SSP), processed recycled concrete aggregates (PRCAs), and waste steel rivet fibers (WSRFs) derived from industrial waste. The research seeks to reduce dependency on virgin materials while maintaining high values of mechanical performance and durability in structural applications. Sixteen concrete mixes were used in the experimental investigations with control, SSP, SSP+RCA, and RCA, reinforced with various fiber dosages (0%, 0.2%, 0.8%, 1.4%) by concrete volume. Workability, density, compressive strength, tensile strength, and water absorption were measured according to the appropriate standards. Compressive and tensile strength increased in all mixes and the 1.4% WSRF mix had the best performance. However, it was found that a fiber content of 0.8% was optimal, which balanced the improvement in strength, durability, and workability by sustainable reuse of recycled materials and demolition waste. It was found by failure mode analysis that the transition was from brittle to ductile behavior as the fiber content increased. The relationship between compressive, tensile strength, and fiber content was visualized as a 3D response surface in order to support these mechanical trends. It is concluded in this study that 15% SSP, 40% PRCA, and 0.8% WSRF are feasible, specific solutions to improve concrete performance and advance the circular economy. Full article

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9 pages, 1953 KB

Open AccessArticle

Mode-Locked Fiber Lasers with Prism-Based Spectral Filters

by Mintae Kang, Taemin Son and Andy Chong

Fibers 2025, 13(8), 108; https://doi.org/10.3390/fib13080108 - 13 Aug 2025

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Abstract

A spectral filter utilizing dispersive prisms and an optical fiber collimator is presented as an attractive alternative to diffraction grating-based spectral filters. A simplified analytical expression for this prism-based spectral filter is derived. A spectral filter constructed using SF11 flint glass prisms demonstrates [...] Read more.

A spectral filter utilizing dispersive prisms and an optical fiber collimator is presented as an attractive alternative to diffraction grating-based spectral filters. A simplified analytical expression for this prism-based spectral filter is derived. A spectral filter constructed using SF11 flint glass prisms demonstrates Gaussian spectral filter profiles with bandwidths of 8 nm and 4 nm, closely matching with theoretical predictions. Using these filters, we demonstrate two types of mode-locking regimes: a dissipative soliton (DS) pulse and a self-similar (SS) pulse. The dissipative soliton pulses deliver 3.3 nJ with dechirped pulse durations of 206 fs, while the self-similar pulses deliver 2.1 nJ with durations of 120 fs. The results demonstrate that the prism-based filters are well-suited for ultrafast mode-locked fiber lasers. Full article

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15 pages, 2101 KB

Open AccessArticle

Hybrid Laminates Reinforced with Natural and Synthetic Fibers: Experimental Characterization and Preliminary Finite Element Assessment for Prosthetic Applications

by Angel D. Castro-Franco, Miriam Siqueiros-Hernández, Virginia García-Angel, Ismael Mendoza-Muñoz, Benjamín González-Vizcarra, Hernán D. Magaña-Almaguer and Lidia E. Vargas-Osuna

Fibers 2025, 13(8), 107; https://doi.org/10.3390/fib13080107 - 11 Aug 2025

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Abstract

Four configuration laminates made of flax, glass, and basalt were fabricated via vacuum-assisted hand lay-up with added weight and tested under ASTM D3039 and D790. The flax–glass–flax lay-up exhibited the highest tensile strength and flexural strength. Orthotropic elastic properties were determined from remanufactured [...] Read more.

Four configuration laminates made of flax, glass, and basalt were fabricated via vacuum-assisted hand lay-up with added weight and tested under ASTM D3039 and D790. The flax–glass–flax lay-up exhibited the highest tensile strength and flexural strength. Orthotropic elastic properties were determined from remanufactured 90°-rotated specimens. A hexahedral-meshed finite element model using these inputs under a 5256 N load predicted the stress and strain within 1% and 5% of the experimental values. These findings demonstrate that flax–glass hybrids offer mechanical reliability, sustainability, and affordability for next-generation prosthetic applications. Full article

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17 pages, 2855 KB

Open AccessArticle

Ballistic Performance of Lightweight Armor Aramid Fabric with Different Bounding Technologies

by István Péter Kondor, János Líska and Zsolt Ferenc Kovács

Fibers 2025, 13(8), 106; https://doi.org/10.3390/fib13080106 - 5 Aug 2025

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Abstract

The aim of this research was to develop a lightweight armor that could be used in bulletproof vests or vehicle protection, offering an alternative to the disadvantageous properties of high-strength steel plates. Specifically, the study focused on investigating the properties of different binders [...] Read more.

The aim of this research was to develop a lightweight armor that could be used in bulletproof vests or vehicle protection, offering an alternative to the disadvantageous properties of high-strength steel plates. Specifically, the study focused on investigating the properties of different binders to identify the most suitable one for further development. The bulletproof characteristics of Kevlar (aramid) fiber fabric (200 g/m², plain weave, CT709) were examined using both the Ansys simulation environment and ballistic laboratory testing. In the experiments, three different layer configurations were tested on 300 × 300 mm specimens, each consisting of 20 layers of Kevlar. The layers were arranged as follows: dry lamination for the first specimen, epoxy binder for the second, and polyurethane binder for the third. Laboratory tests were conducted using 9 mm Parabellum bullets, in accordance with the parameters defined in the MSZ K 1114-1:1999 standard. Both the ballistic and simulation tests indicated that the Kevlar laminated with polyurethane resin demonstrated the most promising performance and is suitable for further development. Full article

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9 pages, 1938 KB

Open AccessBrief Report

Single-Component Silicon-Containing Polyurethane for High-Performance Waterproof and Breathable Nanofiber Membranes

by Dongxu Lu, Yanbing Li, Yake Chai, Ximei Wen, Liming Chen and Sanming Sun

Fibers 2025, 13(8), 105; https://doi.org/10.3390/fib13080105 - 5 Aug 2025

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Abstract

High-performance waterproof and breathable nanofiber membranes (WBNMs) are in great demand for various advanced applications. However, the fabrication of such membranes often relies on fluorinated materials or involves complex preparation processes, limiting their practical use. In this study, we present an innovative approach [...] Read more.

High-performance waterproof and breathable nanofiber membranes (WBNMs) are in great demand for various advanced applications. However, the fabrication of such membranes often relies on fluorinated materials or involves complex preparation processes, limiting their practical use. In this study, we present an innovative approach by utilizing silicon-containing polyurethane (SiPU) as a single-component, fluorine-free raw material to prepare high-performance WBNMs via a simple one-step electrospinning process. The electrospinning technique enables the formation of SiPU nanofibrous membranes with a small maximum pore size (d_max) and high porosity, while the intrinsic hydrophobicity of SiPU imparts excellent water-repellent characteristics to the membranes. As a result, the single-component SiPU WBNM exhibits superior waterproofness and breathability, with a hydrostatic pressure of 52 kPa and a water vapor transmission rate (WVTR) of 5798 g m⁻² d⁻¹. Moreover, the optimized SiPU-14 WBNM demonstrates outstanding mechanical properties, including a tensile strength of 6.15 MPa and an elongation at break of 98.80%. These findings indicate that the single-component SiPU-14 WBNMs not only achieve excellent waterproof and breathable performance but also possess robust mechanical strength, thereby enhancing the comfort and expanding the potential applications of protective textiles, such as outdoor apparel and car seats. Full article

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24 pages, 4254 KB

Open AccessArticle

Strength and Micro-Mechanism of Guar Gum–Palm Fiber Composite for Improvement of Expansive Soil

by Junhua Chen, Yuejian Huang, Aijun Chen, Xinping Ji, Xiao Liao, Shouqian Li and Ying Xiao

Fibers 2025, 13(8), 104; https://doi.org/10.3390/fib13080104 - 31 Jul 2025

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Abstract

This study investigates the improvement effect and micro-mechanism of guar gum and palm fibers, two eco-friendly materials, on expansive soil. The study uses disintegration tests, unconfined compressive strength tests, triaxial compression tests, and SEM analysis to evaluate the enhancement of mechanical properties. The [...] Read more.

This study investigates the improvement effect and micro-mechanism of guar gum and palm fibers, two eco-friendly materials, on expansive soil. The study uses disintegration tests, unconfined compressive strength tests, triaxial compression tests, and SEM analysis to evaluate the enhancement of mechanical properties. The results show that the guar gum–palm fiber composite significantly improves the compressive and shear strength of expansive soil. The optimal ratio is 2% guar gum, 0.4% palm fiber, and 6 mm palm fiber length. Increasing fiber length initially boosts and then reduces unconfined compressive strength. Guar gum increases unconfined compressive strength by 187.18%, further improved by 20.9% with palm fibers. When fiber length is fixed, increasing palm fiber content increases and then stabilizes peak stress and shear strength (cohesion and internal friction angle), improving by 27.30%, 52.1%, and 12.4%, respectively, compared to soil improved with only guar gum. Micro-analysis reveals that guar gum enhances bonding between soil particles via a gel matrix, improving water stability and mechanical properties, while palm fibers reinforce the soil and inhibit crack propagation. The synergistic effect significantly enhances composite-improved soil performance, offering economic and environmental benefits, and provides insights for expansive soil engineering management. Full article

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21 pages, 6717 KB

Open AccessArticle

Structure Design by Knitting: Combined Wicking and Drying Behaviour in Single Jersey Fabrics Made from Polyester Yarns

by Leon Pauly, Lukas Maier, Sibylle Schmied, Ulrich Nieken and Götz T. Gresser

Fibers 2025, 13(8), 103; https://doi.org/10.3390/fib13080103 - 31 Jul 2025

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Abstract

The kinetics of liquid transport in textiles are determined by the thermodynamic boundary conditions and the substrate’s structure. The knitting process offers a wide range of possibilities for modifying the fabric structure, making it ideal for high-performance garments and technical applications. Given the [...] Read more.

The kinetics of liquid transport in textiles are determined by the thermodynamic boundary conditions and the substrate’s structure. The knitting process offers a wide range of possibilities for modifying the fabric structure, making it ideal for high-performance garments and technical applications. Given the highly complex nature of textiles’ interaction with liquids, this paper investigates how fabric structure affects combined wicking and drying behaviour. This facilitates comprehension of the underlying transport processes on the yarn and fabric scale, which is important for understanding the behaviour of the material as a whole. The presented experiment combines analysis of wicking through radial liquid spread using imaging techniques and analysis of the drying process through gravimetric measurement of evaporation. Eight samples of single jersey knitted fabrics were produced using polyester yarns of different texturization and fibre diameters on flat and circular knitting machines. The fabrics demonstrate significantly different wicking behaviours depending on their structure. The fabric’s drying time and rate are directly linked to the macroscopic spread of the liquid. Large inter-yarn pores hinder liquid spread. For the lowest liquid saturations, the yarn structure plays a critical role. Using fine, dense yarns can hinder convective drying within the yarn. Textured yarns tend to exhibit higher specific drying rates. The results offer a comprehensive insight into the interplay between the fabric’s structure and its wicking and drying behaviour, which is crucial for the development of functional fabrics in the knitting process. Full article

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12 pages, 2084 KB

Open AccessArticle

Recycling of PAN Waste into Nonwoven Materials Using Electrospinning Method

by Yaroslav V. Golubev, Igor S. Makarov, Denis N. Karimov, Natalia A. Arkharova, Radmir V. Gainutdinov, Sergey A. Legkov and Sergey V. Kotomin

Fibers 2025, 13(8), 102; https://doi.org/10.3390/fib13080102 - 30 Jul 2025

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Abstract

For the first time, electrospinning has been used to recycle polyacrylonitrile terpolymer (PAN) waste following the solid-phase N-methylmorpholine-N-oxide (NMMO) process from PAN solutions in DMSO into nonwoven materials. The morphology of the obtained material has been studied. The material derived from secondary raw [...] Read more.

For the first time, electrospinning has been used to recycle polyacrylonitrile terpolymer (PAN) waste following the solid-phase N-methylmorpholine-N-oxide (NMMO) process from PAN solutions in DMSO into nonwoven materials. The morphology of the obtained material has been studied. The material derived from secondary raw materials was compared to the material from the original PAN using IR spectroscopy, X-ray diffraction, scanning electron microscopy, and atomic force microscopy. It has been demonstrated that the chemical changes of PAN that occur during NMMO processing do not interfere with nonwoven material manufacture. Spun PAN nonwovens with different histories have similar morphology. It has been shown that the elastic modulus of ultrafine fibers depends on the history of PAN. Single monofilaments produced from initial PAN have a threefold greater elastic modulus than fibers spun from NMMO-recycled polymer. The revealed structure and properties of PAN fibers allow them to be considered as filter materials, as well as precursors of carbon nonwoven fabrics. Full article

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41 pages, 1835 KB

Open AccessReview

A Comprehensive Review of Vertical Forest Buildings: Integrating Structural, Energy, Forestry, and Occupant Comfort Aspects in Renovation Modeling

by Vachan Vanian, Theodora Fanaradelli and Theodoros Rousakis

Fibers 2025, 13(8), 101; https://doi.org/10.3390/fib13080101 - 25 Jul 2025

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Abstract

This current review examines modeling approaches for renovating reinforced concrete (RC) buildings for vertical forest (VF) application, taking into account structural retrofitting, energy systems, forestry integration, and occupant comfort. The study assesses research conducted with an advanced 3D finite element analysis and the [...] Read more.

This current review examines modeling approaches for renovating reinforced concrete (RC) buildings for vertical forest (VF) application, taking into account structural retrofitting, energy systems, forestry integration, and occupant comfort. The study assesses research conducted with an advanced 3D finite element analysis and the use of retrofitting modeling techniques, including textile-reinforced mortar (TRM), fiber-reinforced polymer (FRP), seismic joints, and green concrete applications. The energy system modeling methods are reviewed, taking into account the complexity of incorporating vegetation and seasonal variations. During forestry integration, three main design parameters are identified, namely, root systems, trunks, and crowns, for their critical role in the structural stability and optimal environmental performance. The comfort models are identified evolving from static to adaptive models incorporating thermal, acoustic, visual and air quality parameters. The current review consists of more than one hundred studies indicating that the integration of natural systems to buildings requires a multidimensional and multidisciplinary approach with sophisticated systems. The findings of this review provide the basis for implementing VF models to RC buildings, while highlighting areas requiring further research and validation. Full article

(This article belongs to the Collection Review Papers of Fibers)

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19 pages, 3913 KB

Open AccessArticle

Temperature-Dependent Elastic and Damping Properties of Basalt- and Glass-Fabric-Reinforced Composites: A Comparative Study

by Hubert Rahier, Jun Gu, Guillermo Meza Hernandez, Gulsen Nazerian and Hugo Sol

Fibers 2025, 13(8), 99; https://doi.org/10.3390/fib13080099 - 24 Jul 2025

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Abstract

Fiber-reinforced composite materials exhibit orthotropic behavior, characterized by complex orthotropic engineering constants such as Young’s modulus, Poisson’s ratio, and shear modulus. It is widely recognized that basalt fibers possess superior resistance to elevated temperatures compared to glass fibers. However, the behavior of these [...] Read more.

Fiber-reinforced composite materials exhibit orthotropic behavior, characterized by complex orthotropic engineering constants such as Young’s modulus, Poisson’s ratio, and shear modulus. It is widely recognized that basalt fibers possess superior resistance to elevated temperatures compared to glass fibers. However, the behavior of these fibers within composites at typical operational temperatures for automotive and consumer goods applications has not been thoroughly investigated. A novel measurement setup based on the non-destructive impulse excitation method has been developed for the automated identification of complex orthotropic engineering constants as a function of temperature. This study provides a comparative analysis of the identified engineering constants of bidirectionally fabric-reinforced glass and basalt composites with an epoxy matrix, across a temperature range from −20 °C to 60 °C. The results reveal only minimal differences in stiffness and damping behavior between the examined glass and basalt samples. Full article

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72 pages, 6900 KB

Open AccessReview

Multifunctional Fibers for Wound Dressings: A Review

by Ghazaleh Chizari Fard, Mazeyar Parvinzadeh Gashti, Ram K. Gupta, Seyed Ahmad Dehdast, Mohammad Shabani and Alessandro Francisco Martins

Fibers 2025, 13(8), 100; https://doi.org/10.3390/fib13080100 - 24 Jul 2025

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Abstract

Wound dressings prevent complications such as infections and potentially severe outcomes, including death, if wounds are left untreated. Wound dressings have evolved from rudimentary coverings made from natural materials to sophisticated, functionalized dressings designed to enhance wound healing and support tissue repair more [...] Read more.

Wound dressings prevent complications such as infections and potentially severe outcomes, including death, if wounds are left untreated. Wound dressings have evolved from rudimentary coverings made from natural materials to sophisticated, functionalized dressings designed to enhance wound healing and support tissue repair more effectively. These materials are often referred to as scaffolds in the literature, with wound dressing scaffolds intended to interact with native skin tissue and support tissue regeneration, whereas conventional wound dressings are designed primarily to protect the wound without directly interacting with the underlying tissue. However, there is a functional overlap between these categories, and the boundary is often blurred due to the increasing multifunctionality of modern wound dressings. This review will focus on developing wound dressings (scaffolds or not) based on fibers, their properties, and applications. Advances in nanomedicine have highlighted significant improvements in wound care by applying electrospun nanofibers that mimic the natural extracellular matrix. Therefore, this review explores recent advances in wound healing physiology, highlights nanofiber-based wound dressing materials developed through electrospinning, and distinguishes conventional dressings from multifunctional wound dressing scaffolds. Full article

(This article belongs to the Special Issue Electrospinning Nanofibers)

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Fibers, Volume 13, Issue 8 (August 2025) – 13 articles

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