The authors are thankful to Portugal2020 for funding the project 23958,” TECHNICAL STAPLE CELLULOSIC YARN”, granted by Fundo Europeu do Desenvolvimento Regional, through Compete 2020.
Generally, current clinical imaging methods do not provide highly detailed information about location of axonal injury, severity of injury or expected recovery of patients with traumatic brain injury (TBI). High-Definition Fiber Tractography (HDFT) is a novel imaging modality that allows visualizing and quantifying, directly, the degree of axons damage, predicting functional deficits due to traumatic axonal injury and loss of cortical projections. This imaging modality is based on diffusion technology. Being a novel modality, validation and quality control are essential. Thus this study aims at the development of a brain phantom to mimic the human brain in order to fill some gaps that currently exist in this area. This paper is focused on this novel imaging approach, the role of brain phantoms on its validation and the quality control, as well as, on the materials used in their construction. Furthermore, some important characteristics of fibrous materials for brain phantom are also discussed.
Hemp fibers derived from Cannabis sativa L. have experienced a resurgence in popularity over the past few decades, establishing themselves as one of the most sought-after fibers. This article delves into the intricacies of the hemp production chain, offering a comprehensive understanding from field to fiber. Key aspects covered include the botany of hemp, cultivation requirements, the impact of various factors on plant growth, the harvesting process, different methods of fiber extraction, fibers properties, and suitable spinning processes. Recent studies of hemp’s Life Cycle Assessment are explored, shedding light on how it compares to other sustainable crops and providing insights into the true sustainability of hemp, substantiated by numerical data. The article also addresses challenges encountered throughout the hemp production chain and speculates on future directions that may unfold in the coming years. The overall goal of this study is to provide a knowledge base encompassing every facet of hemp fiber production. It elucidates how different technological approaches and the technical properties of fibers play pivotal roles in determining their ultimate applications. By offering a comprehensive overview, this article contributes to the broader understanding of hemp as a valuable and sustainable resource in the textile industry.
The aim of this review paper is to present a survey on fibrous materials used in key areas of construction and architectural sectors. Here are highlighted conceptual challenges involved in some of the applications trying to define what we call a “green” building. The main applications reviewed are concrete reinforcement, structural health monitoring, insulation, and architectural membranes. On the other hand, tendencies in the area such as sustainability, weight reduction, enhanced durability and resistance, multi-functionality, bio-mimetization and hybridization are also discussed and analysed.
The development of materials with hydrophobic properties has been widely explored in areas such as textiles, healthcare, sports, and personal protective equipment. Hydrophobic properties that arise from nanoparticles (nPs) directly promote other valuable properties, including self-cleaning capabilities, decreased bacterial growth, and increased comfort. In this study, biodegradable poly(ε-caprolactone) (PCL) nanofibers were functionalized by the incorporation of titanium dioxide (TiO 2 ) nPs to develop water-repellent materials. The membranes were produced through electrospinning, and variables such as the polymer concentration, nP concentration, and needle diameter were optimized to achieve PCL/TiO 2 composite fibers with water-repellent capabilities. The nanofibers were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and the water contact angle (WCA). In general, it was observed that the nanofibers presented higher roughness values when TiO 2 nPs were present and that this result promoted higher WCA values. The highest WCA value (156°) was obtained for the nanofiber mat produced with 20% weight-to-volume (w/v) PCL and 0.6% (w/v) TiO 2 .
Current brain imaging methods largely fail to provide detailed information about the location and severity of axonal injuries and do not anticipate recovery of the patients with traumatic brain injury. High-definition fiber tractography appears as a novel imaging modality based on water motion in the brain that allows for direct visualization and quantification of the degree of axons damage, thus predicting the functional deficits due to traumatic axonal injury and loss of cortical projections. This neuroimaging modality still faces major challenges because it lacks a "gold standard" for the technique validation and respective quality control. The present work aims to study the potential of hollow polypropylene yarns to mimic human white matter axons and construct a brain phantom for the calibration and validation of brain diffusion techniques based on magnetic resonance imaging, including high-definition fiber tractography imaging. Hollow multifilament polypropylene yarns were produced by melt-spinning process and characterized in terms of their physicochemical properties. Scanning electronic microscopy images of the filaments cross section has shown an inner diameter of approximately 12 μm, confirming their appropriateness to mimic the brain axons. The chemical purity of polypropylene yarns as well as the interaction between the water and the filament surface, important properties for predicting water behavior and diffusion inside the yarns, were also evaluated. Restricted and hindered water diffusion was confirmed by fluorescence microscopy. Finally, the yarns were magnetic resonance imaging scanned and analyzed using high-definition fiber tractography, revealing an excellent choice of these hollow polypropylene structures for simulation of the white matter brain axons and their suitability for constructing an accurate brain phantom.
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