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The rapid development of additive manufacturing of cementitious materials has enabled the emergence of a new design paradigm, namely functional grading of material properties by location. Target performance parameters could be material weight and insulation value or (particularly important) ductility. A generic concept to achieve this, is through the selective addition of fibres or aggregates. In 3D concrete printing (3DCP), this concept can be developed into two strategies: by adding particles (i) to the bulk mixture through a second stage mixing process at the printer head (Simultaneous Process, SP), or (ii) in between the layers of deposited cementitious filament (Repetitive Sequential Process, RSP). The present paper presents the development of specific equipment required to obtain on–demand functional grading of the printed material. Subsequently, the application of these systems in print trials is shown. The current study focussed on ductility by creating fibre–reinforced 3D printed concrete through both strategies. The mechanical performance of the obtained material has been established through compressive, flexural, and crack–mouth opening displacement tests. To underline the generic nature of the strategies, a trial with lightweight aggregates has also been performed. It was shown that particularly the SP is capable of achieving improvements in ductility and self–weight.

As a promising organic semiconducting material, polymeric graphitic carbon nitride (g-C3N4) has attracted much attention due to its excellent optical and photoelectrochemical properties, thermal stability, chemical inertness, nontoxicity, abundance, and low cost. Its advantageous visible light-induced photocatalytic activity has already been beneficially used in the fields of environmental remediation, biological applications, healthcare, energy conversion and storage, and fuel production. Despite the recognized potential of g-C3N4, there is still a knowledge gap in the application of g-C3N4 in the field of textiles, with no published reviews on the g-C3N4-functionalization of textile materials. Therefore, this review article aims to provide a critical overview of recent advances in the surface and bulk modification of textile fibres by g-C3N4 and its composites to tailor photocatalytic self-cleaning, antibacterial, and flame retardant properties as well as to create a textile catalytic platform for water disinfection, the removal of various organic pollutants from water, and selective organic transformations. This paper highlights the possibilities of producing g-C3N4-functionalized textile substrates and suggests some future prospects for this research area.

Different chemical pre-treatments of Spartium junceum L. fibres using alkali (NaOH), nanoclay (MMT) and Citric acid (CA) with the aim of producing biodegradable composite material are discussed. As environmental requirements in processing technologies have been higher in recent years, the Polylactic acid (PLA) is used in this research as a matrix, due to its renewability, biodegradability and biocompatibility. Biocomposites are prepared by reinforcing PLA with randomly oriented, short Spartium junceum L. fibres in order to increase material strength. The effects of different pre-treatments of Spartium junceum L. fibres on the mechanical properties of final biocomposite material are examined. Fibre tenacity is studied using Vibroscop and Vibrodyn devices. Tensile strength of biocomposite material was measured on the universal electromechanical testing machine Instron 5584. The results indicate that biocomposites reinforced with fibres modified with MMT and CA show upgraded mechanical properties of the final composite material in comparison with the composite materials reinforced with referenced (nontreated) fibres. Infrared spectra of tested fibres and biocomposites were determined with Fourier transform infrared spectroscopy using Attenuated total reflection (FT-IR ATR) sampling technique and the influence of fibre modifications on the fibre/polymer interfacial bonding was investigated. The interface of Spartium/PLA composites was observed with scanning electron microscope (SEM) and it was clearly visible that biocomposites reinforced with fibres modified by MMT and CA showed better interaction of fibres and matrix. Keywords: Fibres, Polymer-matrix composites (PMCs), Mechanical properties, Mechanical testing

Vascular graft replacement remains the optimal treatment option for many vascular diseases despite advances in endovascular surgery. In this study, we proposed the use of surface topographical cues to align and maintain the phenotype of vascular smooth muscle cells (vSMCs) which were reported as one of the vital limitations for successful graft replacement. An auxiliary electrospinning setup has been developed to collect circumferentially aligned fibres on a 3D tubular format; this micro-architecture was found to be similar to the tunica media layer of blood vessels. The presence of aligned fibres served as a signaling modality to induce cell alignment and the maintenance of the contractile phenotype. vSMCs cultured on the 3D aligned fibrous substrate were found to exhibit better cell proliferation ability and enhanced cell-shape directionality. The functional expression of the two representative intracellular contractile proteins (i.e. α-SMA and MHC) was found to exhibit definitive markers that are orderly organized as microfilament bundles. Collectively, the result suggests a possibility of adapting the 3D aligned tubular scaffold to enhance and regulate cell function along with the additional tunability of scaffold diameter and thicknesses for tailoring to the needs of individual patients or future ex vivo studies. ASTAR (Agency for Sci., Tech. and Research, S’pore) Published version

Large data sets of fibre mechanical properties were acquired using automated single fibre tensile testing equipment to improve the reliability of the measurements on T700S, 34-700, T300, HS40 and HYBON 2026 fibres. Although with the same nominal strength and stiffness, the T700S and 34-700 showed different Weibull modulus. A high number (over ~ 200) of the tests is necessary for accurate determination of the fibre strength Weibull parameters; samplings of ~ 50 tests can lead to a Weibull modulus deviation of ±1. Carbon fibre stiffening rate was shown to depend on the fibre type, contrary to previous reported observations. The stiffness of E-glass fibre, however, decreased with the applied strain. The non-linearity of the fibre stress-strain diagrams implies that the necessary compliance calibration should be done iteratively.

Valvasor's library is a unique example of a Seventeenth century personal library, including over 7300 prints and 1530 books. Today, it is kept in the Metropolitan Library of the Zagreb Archdiocese which is part of the Croatian State Archives. In this study, we analysed a selection of papers from Valvasor's collection (VC) of unknown origin and composition. We used a dual approach, combining the results of the analyses of two sets of samples to find the most useful tools for the characterization of historical handmade papers. 144 randomly selected papers were included in the study. As the VC is a cultural heritage, only non-destructive analyses were used, such as visual inspection, surface imaging, measurements of thickness and the determination of optical properties (brightness, yellowness, opacity and gloss). According to the optical properties, papers from the VC could be characterized as yellowish and opaque, without gloss. Due to the fact that the VC papers could not be destroyed, we took another set of samples consisting of 10 historical papers (HP) from archival materials, dating from the 16th to nineteenth century, and subjected them to non-destructive, as well as micro-destructive analyses. This was done to supplement the findings of non-destructive analyses of the original collection. Initially, spot tests were performed to determine water absorbency and to identify the presence of lignin and starch in the paper samples. SEM–EDS and XRF were applied for the identification of inorganic elements. FTIR analyses were used to identify the chemical structures of the paper components. Microscopic analyses were performed in two ways: the paper surface was imaged with a digital microscope, and the morphological characteristics of the fibres were studied using an optical microscope. The dominant fibres present were flax and hemp, with a smaller proportion of cotton. Additionally, thick and thin light brown fibres resembling straw were detected. The presence of calcium-containing components, gelatine and alum could be confirmed with SEM–EDS, XFR and FTIR analysis. Comparing the results of analyses performed on two sets of samples a connection was explored by which it was possible to define the characterization of VC papers. The main goal of the study was to document and characterize a specific collection for the future use of researchers of handmade paper or paper conservators. Furthermore, the study may serve as a model approach for other researchers who seek to document the characteristics of paper in their collections.

Filament-wound composite tubular structures are frequently used in transmission systems, pressure vessels, and sports equipment. In this study, the failure mechanism of composite tubes reinforced with different fibres under low-velocity impact (LVI) and the radial residual compression performance of the impacted composite tubes were investigated. Four fibres, including carbon fiber-T800, carbon fiber-T700, basalt fibre, and glass fibre, were used to fabricate the composite tubes by the winding process. The internal matrix/fibre interface of the composite tubes before the LVI and their failure mechanism after the LVI were investigated by scanning electric microscopy and X-ray micro-computed tomography, respectively. The results showed that the composite tubes mainly fractured through the delamination and fibre breakage damage under the impact of 15 J energy. Delamination and localized fibre breakage occur in the glass fibre-reinforced composite (GFRP) and basalt fibre-reinforced composite (BFRP) tubes when subjected to LVI. While fibre breakage damage occurs globally in the carbon fibre-reinforced composite (CFRP) tubes. The GFRP tube showed the best impact resistance among all the tubes investigated. The basalt fibre-reinforced composite (BFRP) tube exhibited the lowest structural impact resistance. The impact resistance of the CFRP-T700 and CFRP-T800 tube differed slightly. The radial residual compression strength (R-RCS) of the BFRP tube is not sensitive to the impact, while that of the GFRP tube is shown to be highly sensitive to the impact.

In Selective Laser Sintering, fibres are strongly orientated during the powder recoating process. This effect leads to an additional increase of anisotropy in the final printed parts. This study investigates the influence of process parameter variation on the mechanical properties and the fibre orientation. A full factorial design of experiment was created to evaluate the processing parameters of recoating speed, layer thickness and laser power on the part’s modulus of elasticity. Based on the mechanical testing, computed tomography was applied to selected samples to investigate the process-induced fibre microstructure, and calculate the fibre orientation tensors. The results show increasing part stiffness in the deposition direction, with decreasing layer thickness and increasing laser power, while the recoating speed only shows little effect on the mechanical performance. This complies with computed tomography imaging results, which show an increase in fibre orientation with smaller layer thickness. With thinner layers, and hence smaller shear gaps, shear stresses induced by the roller during recoating increase significantly, leading to excessive fibre reorientation and alignment. The high level of fibre alignment implies an increase of strength and stiffness in the recoating direction. In addition, thinner layer thickness under constant laser energy density results in improved melting behaviour, and thus improved fibre consolidation, consequently further increasing the mechanical properties. Meanwhile, the parameters of recoating speed and laser power do not have a significant impact on fibre orientation within their applicable process windows.

The aim of this paper is to evaluate the influence of sustainable surface treatments —performed on flax nonwoven fabrics as textile reinforcement— on the durability of calcium aluminate cement (CAC) based composites. Two treatments are considered: an alkaline treatment (for increased stability and adhesion), and a treatment with soybean oil (to reduce fiber degradation). The cement hydration was studied by analysis of back-scattered scanning electron microscopy images, which revealed variations nearby the fibers owing their capacity for water absorption and presence of oil on the surface. A retarding effect on cement hydration was observed on the composites prepared with the oil-treated fabrics. The composites containing the alkali treated fabrics had better mechanical properties and also the highest durability. For these composites it was found an optimized fiber-matrix adhesion and penetrability of the cement to the fabric.

In this study, differences in the kinetics of the thermal-supported hydrolytic degradation of polylactide (PLA) wet spinning fibres due to material variance in the initial molecular and supramolecular structure were analysed. The investigation was carried out at the microstructural and molecular levels by using readily available methods such as scanning electron microscopy, mass erosion measurement and estimation of intrinsic viscosity. The results show a varying degree of influence of the initial structure on the degradation rate of the studied PLA fibres. The experiment shows that hydrolytic degradation at a temperature close to the cold crystallization temperature is, on a macroscopic level, definitely more rapid for the amorphous material, while on a molecular scale it is similar to a semi-crystalline material. Furthermore, for the adopted degradation temperature of 90 &deg, C, a marginal influence of the pH of the degradation medium on the degradation kinetics was also demonstrated.

Abstract Poultry has become the primary source of dietary protein consumed globally and as a result the by-product feathers are an increasingly problematic industrial waste. Developing a circular economy for feathers is, therefore, an important research area that provides an opportunity to make use of the unique combination of properties of this abundant natural material. This paper reports on the thermal properties of novel feather-based thermal insulation materials. Waste feathers were collected, cleaned and processed into fibres, which were then used to form air-laid nonwoven materials. These have a high fibre content and exploit the excellent natural thermal insulation properties of feathers. The performance of the novel materials developed are tested in order to outline the influence of temperature and density on thermal conductivity and dynamic water sorption. Results are compared to a range of commercially available thermal insulation materials for buildings manufactured from denim, hemp, sheep wool, PET and mineral wool. It was found that air laid feather-fibre fabrics have comparable performance to other fibrous materials and have a thermal conductivity of 0.033 W/(m K) for samples with a density of 59 kg/m3. This is due to the low thermal conductivity of feather fibres and the void structure formed by air-laid processing that effectively traps air. These materials additionally offer improved sustainability credentials as they are derived from a readily available waste that is generally considered to be unavoidable. The paper concludes by highlighting the significant technical and commercial barriers that exist to using waste feathers in thermal insulation products and suggests areas for further research that can exploit the unique properties of feathers. Graphical Abstract

Porous asphalt (PA) mixture is setting off an attractive alternative to be used as surface layer in pavements due to the many profits this mixture provides in terms of noise, safety and environmental aspects. Nonetheless, its use is quite limited due to its low durability in comparison to dense graded asphalt mixtures, reason for which the incorporation of different additives is recommended. In this study, the impact of different types of binders and additives in porous asphalt mixtures are experimentally assessed. A total of 54 experimental designs were defined through the Taguchi design of experiments method. Total air voids, interconnected air voids, particle loss in dry and wet conditions and binder drain down were the responses obtained from the experimental tests. Since more than one response was obtained, three Multi-Criteria Decision-Making (MCDM) methods were performed to turn the multiple response optimisation problem into single-objective optimisation problem. Based on the experimental results and statistical analysis, polymer modified binders improve the ravelling resistance without affecting the functional performance of the mixture and without presenting the risk of binder drain down. ABSTRACT: Porous asphalt (PA) mixture is setting off an attractive alternative to be used as surface layer in pavements due to the many profits this mixture provides in terms of noise, safety and environmental aspects. Nonetheless, its use is quite limited due to its low durability in comparison to dense graded asphalt mixtures, reason for which the incorporation of different additives is recommended. In this study, the impact of different types of binders and additives in porous asphalt mixtures are experimentally assessed. A total of 54 experimental designs were defined through the Taguchi design of experiments method. Total air voids, interconnected air voids, particle loss in dry and wet conditions and binder drain down were the responses obtained from the experimental tests. Since more than one response was obtained, three Multi-Criteria Decision-Making (MCDM) methods were performed to turn the multiple response optimisation problem into single-objective optimisation problem. Based on the experimental results and statistical analysis, polymer modified binders improve the ravelling resistance without affecting the functional performance of the mixture and without presenting the risk of binder drain down. This work was supported by Horizon 2020 Framework Programme [grant number 769373]

The expression waste-to-energy technologies is increasingly being used regarding waste reduction and utilization. Waste-to-energy technologies are procedures used to generate different forms of energy starting from a waste source. Considering that this pap waste, the previously mentioned procedures can be divided into mechanical, thermal and chemical treatment of composite waste. Thermal treatment processes provide a wide range of options to produce electricity, heat, oils, gases, fuels and chemicals starting waste. Some procedures are used for commercial purposes, while many are still being developed in laboratories or semi-industrial plants. The presented paper is focused to briefly review recent ld of thermal treatment of composite waste materials. Proizvodnja energije iz otpadnih materijala primenom različitih tehnologija je jedan od načina ponovne upotrebe i ujedno redukcije otpadnih materijala. Sve ove tehnologije reciklaže imaju jednu zajedničku karakteristiku - dobijanje energije u različitim oblicima, polazeci od otpadnih materijala kao sirovina. Imajuci u vidu da je ovaj rad fokusiran na kompozitne otpadne materijale, pomenute procedure se mogu podeliti na mehaničke, termičke i hemijske tretmane kompozithog otpada. Termički tretmanima kompozitnog otpada je moguća proizvodnja energije u vidu eliktriciteta, toplote, ulja, gasova, goriva i različitih hemijskih jedinjenja. Pojedine procedure su uvedene u komercijalnu upotrebu, dok se veliki broj njih trenutno razvija u laboratorijskim ili poluindustrijskim postrojenjima. U radu je ukratko dat prikaz trenutnog stanja i inovacija u oblasti termičkog tretmana otpadnih kompozitnih materijala.

In this study, the back calculated compressive properties of flax fibers utilizing the Impregnated Fiber Bundle Test (IFBT) were investigated. The back calculated stress-strain response can be described by the Ramberg-Osgood model. The compressive modulus of the fiber is similar to its tensile modulus. The compressive strength of the fiber is approximately 45 % of its tensile strength. Considering the presence of local fiber kinking within the elementary fibers as well as global fiber kinking due to fiber misalignments and plastic shear deformation in the matrix material, this is a remarkably high value for the compressive strength. Our results indicate that local fiber kinking precedes global fiber kinking. We show that IFBT is a promising method for determining the compressive properties of flax fibers and provides necessary input data for finite element analysis of the compressive failure mechanisms in unidirectional flax fiber reinforced composites. QC 20220215

In order to provide more effective treatment strategies for the rapid healing of diabetic wounds, novel therapeutic approaches need to be developed. The therapeutic potential of peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist pioglitazone hydrochloride (PHR) in two different release kinetic scenarios, burst release and sustained release, was investigated and compared with in vitro and in vivo tests as potential wound healing dressings. PHR-loaded fibrous mats were successfully fabricated using polyvinyl-pyrrolidone and polycaprolactone by scalable pressurized gyration. The results indicated that PHR-loaded fibrous mats expedited diabetic wound healing in type-1 diabetic rats and did not show any cytotoxic effect on NIH/3T3 (mouse embryo fibroblast) cells, albeit with different release kinetics and efficacies. The wound healing effects of fibrous mats are presented with histological and biochemical evaluations. PHR-loaded fibrous mats improved neutrophil infiltration, oedema, and inflammation and increased epidermal regeneration and fibroblast proliferation, but the formation of hair follicles and completely improved oedema were observed only in the sustained release form. Thus, topical administration of PPAR-γ agonist in sustained release form has high potential for the treatment of diabetic wounds in inflammatory and proliferative phases of healing with high bioavailability and fewer systemic side effects.

Two different commercial bleaching products containing hypochlorite were used on different fabrics (plain-weave cotton, knitted cotton, plain-weave polyester-cotton and knitted lycra-cotton) to verify possible fibres damages. Bleaching products differ each other for the alkaline formulation. In particular, one of them has an alkaline bleaching formulation and the other has a low-alkaline bleaching formulation. The degree of whiteness, the tensile and bursting strength, and the thermal and surface properties were evaluated after a different number of washing cycles. The obtained results reveal that the alkaline bleaching product is better than the low-alkaline bleaching product in maintaining mechanical properties and in improving optical properties of the fabrics.

The hybrid configuration of bio-reinforced composites has established a new extended boundary for the development of pro-ecological technologies due to light weight, moderate specific strength, low cost, environmental benefits, and potential applications of natural components. This work investigates the physical and mechanical properties of hybrid composites made of sisal/glass fibres and Portland cement inclusions. A full factorial design was generated to identify the effects of the stacking sequence and cement particles on the flexural strength, flexural stiffness, apparent density, apparent porosity and water absorption of the composites. The significant contributions of these main factors and their interactions were determined via Design of Experiments (DoE) and Analysis of Variance (ANOVA). The fracture features and damage mechanisms of hybrid composite were also reported. The inclusion of cement microparticles led to an increased apparent porosity, as well as enhanced water absorption, flexural stiffness and flexural strength of the hybrid composites. The mechanical properties were strongly dependent on the fibre stacking sequence, which accounts for approximately 98% of the effects observed. Moreover, the stacking sequence affected the damage mechanism of the bio-composites. Finally, the replacement of glass fibres by unidirectional sisal reinforcements may potentially improve the specific properties in structural applications with an environmental sustainable footprint.

[EN] Traditionally, glass fibre has been used as plastic reinforcement whenever mechanical properties of a matrix, like stiffness, do not meet the specifications. However, current tendencies try to replace glass fibres by more sustainable fibres to obtain eco-friendlier products. Natural fibres show comparatively good physical and mechanical properties and, unlike glass fibres, come from renewable resources and are recyclable and sustainable. In this work, hemp straw discarded from hemp manufacturing was used as reinforcement in polypropylene composites. One drawback associated to hemp straw is its high lignin content that reduces its reinforcing potential. Therefore, a soft alkaline treatment was employed to adjust the lignin contents. In this work, the evolution of the Young's modulus with the NaOH treatment is assessed and discussed. Intrinsic Young's moduli of hemp straw fibres at different alkaline conditions were determined by Hirsch model. Finally, Tsai-Pagano and Halpin-Tsai equations allowed the prediction of the theoretical Young's modulus of the composites. The results showed the competitiveness of a by-product reinforced composite in front of commodity materials.

The use of Natural Fibers in cementitious composites is an innovative technical solution but, they are characterized by a complex microstructure and significant heterogeneity, which influence their interaction with cementitious matrices, whose identification requires further advances in the current state of knowledge. The present study summarizes the results of a wide series of pull-out tests carried out on sisal, curaua and jute fibers. Then, the experimental results are employed in an inverse identification procedure aimed at unveiling the key features of the aforementioned bond-slip laws. Morphological, chemical, physical and mechanical characterization of the natural fibers were correlated with the resulting bond properties within the embedding matrix. The obtained results in terms of relevant parameters, such as bond strength and fracture energy (under pull-out stresses) of the fiber-matrix interface, pave the way for future studies intended for a better understanding of the structural response of Natural Fiber Reinforced Cementitious Composites.

© 2018, © 2018 Institute of Materials, Minerals and Mining and ASM International Published by Taylor & Francis on behalf of the Institute and ASM International. Fibre-hybrid composites are composed of two or more fibre types in a matrix. Such composites offer more design freedom than non-hybrid composites. The aim is often to alleviate the drawbacks of one of the fibre types while keeping the benefits of the other. The hybridisation can also lead to synergetic effects or to properties that neither of the constituents possess. Even though fibre-hybrid composites are attractive, they also pose more challenges in terms of materials selection than conventional, single fibre type composites. This review analyses the mechanisms for synergetic effects provides guidance on the fibre and matrix selection and describes recent opportunities and trends. It finishes by describing the current applications, and by contrasting how the industrial use is different from the academic research. ispartof: INTERNATIONAL MATERIALS REVIEWS vol:64 issue:4 pages:181-215 status: published

Man-made lignocellulosic fibres were successfully prepared from unbleached birch kraft pulps by using the Ioncell-F technology. Pulps with different lignin content were produced by tailored kraft pulping with varying intensity. The degree of polymerization of the pulps was adjusted by acid-catalyzed hydrolysis and electron beam treatment. All substrates were completely soluble in 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH] OAc) and the respective solutions were spinnable to yield fibres with good to excellent mechanical properties despite the use of only mildly refined wood pulp. The tensile properties decreased gradually as the lignin concentration in the fibres increased. Changes in the chemical composition also affected the structure and morphology of the fibres. Both the molecular orientation and the crystallinity decreased while the presence of lignin enhanced the water accessibility. The effects of the crystallite size and lignin content on monolayer water adsorption are discussed.

Steel Mesh-Reinforced Cementitious Composites (SMRCC) (traditionally known as ferrocement) have been in existence for few decades, but have some limitations set on element thickness and number of reinforcing mesh layers and the resulting deflection ductility. Therefore, the author has made an attempt to explore whether deflection ductility will improve in mesh-reinforced cementitious composites (25 mm thick) if discontinuous fibres are added to slab elements. For this purpose, thin slab elements of dimensions 700 mm (length) × 200 mm (width) × 25 mm (thickness) were cast and subjected to four point bending tests. Based on the flexural tests conducted on SMRCC (Control Slab Elements, cast with Steel Mesh Volume of reinforcement, MVr=0.78, 0.94, and 1.23%) and Hybrid Mesh-and-Fibre-Reinforced Cement Based Composite (HMFRCBC) (Test Slab Elements, combining MVr=0.78, 0.94 and 1.23% and Polyolefin Fibre Volume fraction, PO-FVf=0.5-2.5% of volume of specimens, with 0.5% interval), load-deflection and the deflection ductility index were analyzed. From the flexural load-deflection curves it has been observed that HMFRCBC slabs demonstrate higher flexural load-carrying capacity and deflection ductility when compared to SMRCC slabs. This study shows that higher the polyolefin fibre volume fraction (PO-FVr) from 0.5 to 2.5% (with a 0.5% interval) in HMFRCBC slabs, the higher the flexural deflection ductility. The Deflection Ductility Index (DDI) of HMFRCBC (with 5 layers of mesh and PO-FVr=2.5%) is 4.5 times that of SMRCC. This study recommends that HMFRCBC can be used as an innovative construction material due to its higher flexural ductility characteristics.

The complex structure of the annulus fibrosus is strongly related to its mechanical properties. Recent work showed that it is possible to observe the relative movement of fibre bundles in loaded cow tail annulus; the aim of this work was to describe and quantify annulus fibrosus micromechanics in degenerated human disc, and compare it with cow tail annulus, an animal model often used in the literature. Second harmonic generation was used to image the collagen matrix in twenty strips of annulus fibrosus harvested from intervertebral disc of seven patients undergoing surgery. Samples were loaded to 6% tensile strain in 1% steps. Elastic modulus was calculated from loading curves, and micromechanical strains were calculated from the images using custom software. The same protocol was applied to twenty strips of annulus harvested from cow tail discs. Significant morphological differences were found between human and cow tail samples, the most striking being the lack of collagen fibre crimp in the former. Fibres were also observed bending and running from one lamella to the other, forming a strong flexible interface. Interdigitation of fibre bundles was also present at this interface. Quantitative results show complex patterns of inter-bundle and inter-lamellar behaviour, with inter-bundle sliding being the main strain mechanism. Elastic modulus was similar between species, and it was not affected by the degree of degeneration. This work gives an insight into the complex structure and mechanical function of the annulus fibrosus, which should be accounted for in disc numerical modelling. Electronic supplementary material The online version of this article (doi:10.1007/s10237-017-0900-z) contains supplementary material, which is available to authorized users.

This work shows the practical application and the experimental validation of a procedure based on an algorithm, running in a finite element environment, able to operate inside a convex three-dimensional solid by replacing the continuous mass with an appropriate cancellous bone-inspired space frame sharing, with the solid, the border and organized for having the fibres oriented according to the boundary conditions. The purpose is to reach the maximum mechanical efficiency realizing a load adaptive space frame optimized in terms of weight. Young's moduli of a cubic virtual specimen were numerically estimated. Fifteen specimens were printed by a 3D printer using a titanium alloy. Numerical results were compared with experimental ones obtained by tensile tests. The simulation results confirmed the validity of the FEM “beam element-based” space frame.

In most of cases, technological processing leads to microstructure anisotropy of material. Results obtained from the analysis of anisotropy can be used for evaluation of material properties and parameters of technology processes. Stereological metallography was used for describing of structure anisotropy. In case of plastically deformed material, degree of orientation of grain boundaries was determined. Grain boundaries are decomposed into isotropic, planar and linear oriented components - specific surface area of grain boundaries and these parameters were measured using oriented test lines stereology method. These results were used for estimation of local plastic deformation using conversion model of orientation grain boundaries to deformation of grains. Our proposed conversion method enables estimation of local plastic deformation in arbitrary place of body with arbitrary state of initial deformation. In case of short fibre reinforced thermoplastics oriented test plane stereology method was used for estimation of experimental orientation of fibres. Degree of orientation was estimated from the number of intersections of fibres with test planes and from these results components of an orientation tensor are estimated. This method is very simple in comparison with a current method which is based on measurement of dimensions and orientation of lot of fibre intersections in analyzed plane.

The introduction of Variable-Stiffness Laminates requires not only the use of advanced numerical simulation tools but also better understanding of manufacturing induced effects. These computational tools can give beneficial insight that will lead to an effective reduction of test campaigns as well as to increase design possibilities. This paper presents a virtual testing approach to study the influence of tow-drop effects, generated in the manufacturing of steered-fibre composites, by means of nonlinear finite element analyses within the framework of fracture and damage mechanics. X-ray computed tomography was used to characterise the embedded resin-rich areas. Both the progressive failure mechanisms and the ultimate failure loads can be predicted with high realism when compared with experimental observations. In addition, the differences of the tow-drop effects on plain and notched laminates can also be predicted accurately The authors acknowledge the financial support of the Ministerio de Economía y Competitividad of Spain under project MAT2009-07918. The first author would also like to thank the Generalitat de Catalunya for the FI pre-doctorate Grant 2010FI_B00658

Nanofibers of poly(vinyl alcohol) (PVA) reinforced with cellulose nanofibrils (CNFs) and/or crosslinked with maleic anhydride (MA) were produced by electrospinning technique to compare the additivation effects of the polymeric matrix. The results suggested that the PVA mass fraction equal to 14%, CNFs volumetric fraction of 3% and maleic acid at the molar ratio 20:1 are the best proportions for renewable base fibres production. In this study, the best electrospinning parameters for membranes production were obtained at the applied voltage of 24 kV, needle tip-to-collector distance of 14.5 cm, feed rate of 0.3 mL h1 and using a plate collector. CNFs and MA additions allow to improve nanofiber thermal properties and resistance to water degradation, which result in an eco-friendlier, biocompatible and long-term biodegradable nanofiber mats with diameters of 74±33 nm for water filtration purposes., The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) for funding the project UID/CTM/00264/2013 and A. Zille contract IF/00071/2015., info:eu-repo/semantics/publishedVersion

Crosslinking of an unsaturated aliphatic polyester poly(globalide) (PGl) by bistriazolinediones (bisTADs) is reported. First, a monofunctional model compound, phenyl&ndash, TAD (PTAD), was tested for PGl functionalisation. 1H-NMR showed that PTAD&ndash, ene reaction was highly efficient with conversions up to 97%. Subsequently, hexamethylene bisTAD (HM&ndash, bisTAD) and methylene diphenyl bisTAD (MDP&ndash, bisTAD) were used to crosslink electrospun PGl fibres via one- and two-step approaches. In the one-step approach, PGl fibres were collected in a bisTAD solution for in situ crosslinking, which resulted in incomplete crosslinking. In the two-step approach, a light crosslinking of fibres was first achieved in a PGl non-solvent. Subsequent incubation in a fibre swelling bisTAD solution resulted in fully amorphous crosslinked fibres. SEM analysis revealed that the fibres&rsquo, morphology was uncompromised by the crosslinking. A significant increase of tensile strength from 0.3 &plusmn, 0.08 MPa to 2.7 &plusmn, 0.8 MPa and 3.9 &plusmn, 0.5 MPa was observed when PGI fibres were crosslinked by HM&ndash, bisTAD and MDP&ndash, bisTAD, respectively. The reported methodology allows the design of electrospun fibres from biocompatible polyesters and the modulation of their mechanical and thermal properties. It also opens future opportunities for drug delivery applications by selected drug loading.

International audience; Living cells embedded in a complex Extra–Cellular Matrix (ECM) migrate in a sophisticated way thanks to adhesions to matrix fibres and contractility. It is important to know what kind of forces are exerted by the cells. Here we use reflectance confocal microscopy to locate fibres accurately and determine displacement fields. Correlation techniques are used to this aim, coupled with proper digital image processing. Benchmark tests validate the method in the case of shear and stretching motions. Finally, the method is tested successfully for studying cancer cells migrating in collagengels of different concentration.KEYWORDS: Displacement field, phase correlation, confocal microscopy, cell migration, fibres, cancer cells.

Glass fibres slowly degrade due to dissolution when exposed to water. Such environmental aging results in the deterioration of the mechanical properties. In structural offshore and marine applications, as well as in the wind energy sector, R-glass fibre composites are continuously exposed to water and humid environments for decades, with a typical design lifetime being around 25 years or more. During this lifetime, these materials are affected by various temperatures, acidity levels, and mechanical loads. A Dissolving Cylinder Zero-Order Kinetic (DCZOK) model was able to explain the long-term dissolution of R-glass fibres, considering the influence of the pH , temperature, and stress corrosion. The effects of these environmental conditions on the dissolution rate constants and activation energies of dissolution were obtained. Experimentally, dissolution was measured using High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). For stress corrosion, a custom rig was designed and used. The temperature showed an Arrhenius-type influence on the kinetics, increasing the rate of dissolution exponentially with increasing temperature. In comparison with neutral conditions, basic and acidic aqueous environments showed an increase in the dissolution rates, affecting the lifetime of glass fibres negatively. External loads also increased glass dissolution rates due to stress corrosion. The model was able to capture all of these effect © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

The spread of antimicrobial resistance calls for chronic wound management devices that can engage with the wound exudate and signal infection by prompt visual effects. Here, the manufacture of a two-layer fibrous device with independently-controlled exudate management capability and visual infection responsivity was investigated by sequential free surface electrospinning of poly(methyl methacrylate-co-methacrylic acid) (PMMA-co-MAA) and poly(acrylic acid) (PAA). By selecting wound pH as infection indicator, PMMA-co-MAA fibres were encapsulated with halochromic bromothymol blue (BTB) to trigger colour changes at infection-induced alkaline pH. Likewise, the exudate management capability was integrated via the synthesis of a thermally-crosslinked network in electrospun PAA layer. PMMA-co-MAA fibres revealed high BTB loading efficiency (&gt, 80 wt.%) and demonstrated prompt colour change and selective dye release at infected-like media (pH &gt, 7). The synthesis of the thermally-crosslinked PAA network successfully enabled high water uptake (WU = 1291 &plusmn, 48 &minus, 2369 &plusmn, 34 wt.%) and swelling index (SI = 272 &plusmn, 4 &minus, 285 &plusmn, 3 a.%), in contrast to electrospun PAA controls. This dual device functionality was lost when the same building blocks were configured in a single-layer mesh of core-shell fibres, whereby significant BTB release (~70 wt.%) was measured even at acidic pH. This study therefore demonstrates how the fibrous configuration can be conveniently manipulated to trigger structure-induced functionalities critical to chronic wound management and monitoring.

Acknowledgements: The authors are grateful to FEDER – Fundo Europeu de Desenvolvimento Regional, in the aim of COMPETE 2020 with the copromotional project WOWW - World of Outstanding Wool and Wood and to Portuguese Foundation for Science and Technology (FCT) through the Project reference UID/Multi/04044/2013 and PAMI – ROTEIRO/0328/2013 (Nº 022158). The authors gratefully acknowledge the contribution to language revision of Dr Sonia Fiuza. The Coimbra Chemistry Centre, CQC, supported by FCT, through the project PEstOE/QUI/UI0313/2013 is also acknowledged In the last decades the studies on thermoplastic composites reinforced with natural fibres have been mostly focused on vegetable lignocellulosic or cellulosic fibres. These materials provide eco-sustainable solutions for a large range of applications and have been actually adopted by multiple industries. The interest on fibres of animal origin is more recent and research on composites reinforced with these fibres predominantly composed of keratin, such as wool, feathers or silk, is increasing in virtue of some advantageous properties that may overcome some of the intrinsic limitations from vegetable fibres. The combined use of vegetable and animal fibres in composites appropriate for melt blending processing is at early stages of research. After chemical treatments, the fibres of animal origin have been mostly applied as binders between vegetable fibres and polymers, but not as main constituents of these composites. The use of both types of fibres simultaneously in composites of thermoplastic matrices is the subject of the present study where the fibres of animal origin (wool) are sourced from different kinds of residues from a textile industry and the fibres of vegetable origin (wood) are the residues from carpentry activities. The chemical composition, the macro and microstructure of the fibres is analyzed, as well as that of the composites that combine non-biodegradable and biodegradable polymers with diverse ratios of the fibres in different conditions (wool as cards, yarns and felt cloths; wood as sawdust). The addition of coupling agents to enhance the compatibility between wool, wood and different polymers is also analysed. info:eu-repo/semantics/publishedVersion

International audience; Ceramic matrix composite (CMC) materials have been considered a desired solution for lightweight and high-temperature applications. Simultaneously, among all different CMC reinforcements, polymer-derived ceramic (PDC) fibres have gained attention for the intrinsic thermal stability and mechanical strength with simple and cost-effective synthesis techniques. Here, carbon-rich SiOCN fibres were synthesized via hand-drawing and polymer pyrolysis of a hybrid precursor of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasilazane (TTCSZ) and poly-acrylic acid (PAA). The type of silazane reported in this work is considered as a major precursor for SiCN; however, it is unspinnable, due to its unfavourable physical properties (low viscosity) and chemical structure (cyclic rather than linear structure). The introduction of PAA to TTCSZ to create a hybrid precursor remarkably improved the spinnability of the silazane and should be widely applicable to other unspinnable PDC pre-ceramic polymers. Investigations on the structural and compositional development of the fibres were mainly conducted via Raman spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, nuclear magnetic resonance and thermo-gravimetric analysis to determine spinnability, free carbon content, cross-linking and pyrolysis behaviour of the fibres, respectively.

Anterior Cruciate Ligament (ACL) is one of the main ligaments within the knee. ACL is a dense fibrous tissue, its nonlinear stress-strain behaviour is related to fibres uncrimping, reorienting and tensioning, which inherently define its functional properties. Aim of this study was to design a setup able to acquire the 3D fibrous microstructure of ACL samples evolving under strain. A specific tensioning device – consisting in two clamps to hold the sample, a linear guide moved by a threaded rod for sample elongation, a load cell to measure reaction force and an aluminum frame – was designed to be inserted into the chamber of a high resolution micro-CT system (Skyscan 1176). Once clamped, ACL underwent 1, 2, 3, 4, 6 and 8% of elongation to reveal toe and linear region of the stress-strain curve. At each specific strain, specimen was scanned with a nominal resolution of 9 μm to non-destructively obtain 3D microstructure. Before testing, collagen fibres were highlighted by an optimized contrasting protocol which included the staining of ACL in a solution of 2% PTA in H2O. With the specific contrasting procedure and micro-CT resolution, it was possible to show the effect of strain variation on the different fibres bundles. Presented procedure makes it possible to obtain fundamental information about mechanical and microstructural characteristics, simultaneously addressing clinical and engineering issues related to ACL reconstruction. Current work is related to micro-CT image processing, in order to perform a 3D morphometric analysis on the fibres bundle changes in relation to their mechanical behaviour.

A simple and effective process combining pressure and gyration has been developed and used to jet-out composite fibres containing graphene nanoplatelets. Thermoplastic polyurethane and phenolic resin polymers were used as matrices. Processing parameters such as rotation speed, pressure and polymer concentration had a marked influence on the composite fibre diameter. Focussed ion beam milling and etching verified the effective incorporation of the graphene nanoplatelets into the composite fibres. Morphological, rheological, physico-chemical and thermal properties of the composite fibres were evaluated to identify possible applications for them.

Environmentally-friendly monofilament cellulosic fibres have been widely used as alternatives for conventional steel reinforcement within concrete. Recently, the use of cellulosic fibre fabrics and their fabric reinforced polymer composites as reinforcement materials within and/or outside of construction materials (e.g. concrete) has gained popularity due to their inexpensive cost and favourable specific mechanical properties compared with synthetic fibre fabrics (e.g. E-glass). This review presents a summary of recent development on cellulosic fibre Fabric Reinforced Cementitious (FRC) and Fabric Reinforced Geopolymer (FRG) composites, as well as their cellulosic Fabric Reinforced Polymer (FRP) composites as reinforcements of concrete, masonry and timber structures for civil engineering applications. This review covers: (1) properties (i.e. chemical composition, microstructure, mechanical properties and cost) of monofilament cellulosic fibres and their comparison with synthetic fibres, the relationship between fibre chemical composition and fibre mechanical properties, parameters affect fibre properties; (2) properties (e.g. fabrication of monofilament fibres to fabrics and structures) of cellulosic fibre fabrics, properties of polymer matrices, and properties (i.e. flexural, tensile, impact, insulation and fire properties) of cellulosic fabric FRP composites; and (3) properties (compressive, flexural and tensile and impact properties) of cellulosic FRC and FRG composites, and the properties of cellulosic FRP composites reinforced concrete, masonry and timber structures. In addition, the degradation mechanisms of cellulosic FRC and FRP are discussed. Furthermore, the durability of FRC, FRG and FRP composites are reviewed and the methods to improve the durability of FRC, FRG and FRP composites from the aspects of fibre modification and matrix modification are reviewed and summarized.

This paper presents a tension stiffening model for Fiber Reinforced Concrete (FRC) tensile member reinforced by hybrid glass fiber reinforced polymer (GFRP) and steel bars. The model is developed through an explicit analytical bond formulation by considering a four-linear bond shear stress-slip relationship to simulate the bond behavior between reinforcing bars and surrounding FRC. The model is also capable of simulating both the fiber reinforcement contribution and the yielding stage of steel bar at cracked section. Additionally, a FE Model is carried out using a multi-directional smeared crack approach for modeling cracking process in FRC, and adopting interface finite elements to simulate the bond behavior between reinforcements and FRC, whose constitutive model was defined from the aforementioned bond law. Both the analytical and numerical approaches showed a good agreement with some recent experimental results on tension-stiffening in the literature. Finally, an extensive parametric study is performed by using the analytical model, and the influence of the involved parameters on the tension-stiffening and cracking behavior of hybrid GFRP/steel FRC tensile member is investigated., QREN project n. 30367 – UrbanCrete, Portuguese Foundation for Science and Technology (FCT) - SFRH/BD/77409/2011

The durability of textile membranes in outdoor architectural applications is a key factor to be considered in a specific project design. The degradation of the polymers within the coating and its propagation to the fibres contributes to the loss of functional performance, mainly in terms of mechanical properties. The aim of this work was to study the durability of two architectural membranes: one produced with polyester fibre coated with polyvinylchloride (PVC) and other produced with glass fibre coated with polytetrafluorothylene (PTFE) at the initial stages of environmental exposure. These materials were subjected to an in-situ degradation in a real environment and a rapid degradation by the action of moisture and ultraviolet radiation in an accelerated aging chamber over a period of 2160 hours (3 months). The effect of these agents on the degradation and thus the durability of the membranes was evaluated by the loss of mechanical performance (tensile strength test) and thermal performance levels (Alambeta test). In addition to mechanical and thermal analyses, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis were performed, in order to understand the effect of the degradation agents on the surface of the membranes. The mechanical performance of the polyester/PVC membranes has shown unchangeable properties, while the glass fibre /PTFE membrane has presented a reduction on tensile strength properties. These reduction was more significant when the membrane were subjected to the accelerated degradation test, showing a decrease of resistance of about 34% and 43% on longitudinal and transversal direction, respectively for the period of 2160 hours. SEM images of polyester/PVC membranes did not show any significant difference over time, however EDS analysis showed a loss of 52% of the chlorine element. For glass fibre /PTFE membrane, SEM and EDS analysis didn’t show any significant difference over degradation time.

Structural health monitoring to assess the safety, durability and performance of structures can be performed by non-destructive methods such as the measurement of impedance in self-sensing cement-based elements. Cement-based materials, like mortars and concretes, generally have high electrical resistivity but the addition of carbon-based fillers and fibres decreases their electrical resistivity and thus enhances their self-sensing capabilities. In this study, two waste carbon-based fillers, namely, used foundry sand and gasification char were compared to commercial graphene nanoplatelets and used to produce self-sensing cement mortars, both with and without recycled or virgin carbon fibres. The mortars were tested in terms of their mechanical and electrical properties as well as their propensity to capillary water absorption. The results demonstrate that gasification char alone is the best carbonaceous waste for decreasing the electrical resistivity (&minus, 42%) and water absorption (&minus, 17%) of mortars, while their compressive strength remains unaltered. Moreover, although there is a slight reduction in compressive strength and an increase in water suction when gasification char is coupled with fibres, the combination of fillers and fibres has a synergistic effect in decreasing mortars&rsquo, electrical resistivity, especially when recycled carbon fibres are used (&minus, 80%).

The static response of ballistic panels and also its resistance to blast and ballistic impact is investigated in the framework of this study. By connecting individual ballistic panels together, the protective barrier can be constructed. The protective barrier can be featured as a system with high mobility and versatility that is achieved by linking basic interlocking plate elements together. The resulting protective barrier can be shaped according to many possible scenarios in a wall with various possible opening angles and a small post with the tetragonal base or a larger post with the hexagonal ground plan. The material solution of the protective barrier benefits from the application of ultra-high-performance fibre-reinforced cement-based composites (UHPFRCC), which meets the requirements for enhanced resistance against extreme loads such as blast or impact. Besides, by using UHPFRCC, thin and slender design can be adopted, which is advantageous in many ways. Slender design results in a lower weight, allowing for easy manipulation and replacement. To verify the behavior of the panels, the proposed barrier was subjected to various loadings at different strain rates. The experimental campaign demonstrated that the protective barrier has a reasonable load-bearing capacity and also sufficient resistance against projectile impact and blast effects.

International audience; The use of biomass in injection moulded or extruded thermoplastic composites is an important issue, especially when trying to add value to low-cost co-products. The objective of this work was to conduct a complete study on the morphological characterisation and carbohydrate analysis of a range of co-products obtained during the processing of flax straw. Thus, the morphology of (i) cut flax fibres, (ii) fragmented shives, and (iii) scutching and carding dusts is characterised using a dynamic image analyser with a sieving approach. These different fractions are then used to produce injection moulded composite materials. Their mechanical performances are discussed in relation to the morphology of the reinforcements, as well as their carbohydrate compositions and fine particle contents. Co-products, based on their reinforcement properties, can be classified into three categories. In all cases, a reinforcing effect is demonstrated for the tensile Young’s modulus with an increase from + 24 to + 137% depending of the material. A linear relationship was observed between the cellulose content of reinforcing material and the tensile strength at break of the injection moulded composites. The results are promising for adding value to all flax co-products in plastics processing, targeting industrial applications in line with their intrinsic performances.

Foamed concrete (FC) is a high-quality building material with densities from 300 to 1850 kg/m3, which can have potential use in civil engineering, both as insulation from heat and sound, and for load-bearing structures. However, due to the nature of the cement material and its high porosity, FC is very weak in withstanding tensile loads; therefore, it often cracks in a plastic state, during shrinkage while drying, and also in a solid state. This paper is the first comprehensive review of the use of man-made and natural fibres to produce fibre-reinforced foamed concrete (FRFC). For this purpose, various foaming agents, fibres and other components that can serve as a basis for FRFC are reviewed and discussed in detail. Several factors have been found to affect the mechanical properties of FRFC, namely: fresh and hardened densities, particle size distribution, percentage of pozzolanic material used and volume of chemical foam agent. It was found that the rheological properties of the FRFC mix are influenced by the properties of both fibres and foam; therefore, it is necessary to apply an additional dosage of a foam agent to enhance the adhesion and cohesion between the foam agent and the cementitious filler in comparison with materials without fibres. Various types of fibres allow the reduction of by autogenous shrinkage a factor of 1.2–1.8 and drying shrinkage by a factor of 1.3–1.8. Incorporation of fibres leads to only a slight increase in the compressive strength of foamed concrete; however, it can significantly improve the flexural strength (up to 4 times), tensile strength (up to 3 times) and impact strength (up to 6 times). At the same time, the addition of fibres leads to practically no change in the heat and sound insulation characteristics of foamed concrete and this is basically depended on the type of fibres used such as Nylon and aramid fibres. Thus, FRFC having the presented set of properties has applications in various areas of construction, both in the construction of load-bearing and enclosing structures.

In order to increase the material throughput of aligned discontinuous fibre composites using technologies such as HiPerDiF, stability of the carbon fibres in an aqueous solution needs to be achieved. Subsequently, a range of surfactants, typically employed to disperse carbon-based materials, have been assessed to determine the most appropriate for use in this regard. The optimum stability of the discontinuous fibres was observed when using the anionic surfactant, sodium dodecylbenzene sulphonate, which was superior to a range of other non-ionic and anionic surfactants, and single-fibre fragmentation demonstrated that the employment of sodium dodecylbenzene sulphonate did not affect the interfacial adhesion between fibres. Rheometry was used to complement the study, to understand the potential mechanisms of the improved stability of discontinuous fibres in aqueous suspension, and it led to the understanding that the increased viscosity was a significant factor. For the shear rates employed, fibre deformation was neither expected nor observed.

The article describes tests of epoxy mortars after the addition of fibres. The fibres were a substitute for sand in the amount of 0, 1, 2, 3, 4 and 5% by volume, respectively. Three types of mortar were obtained, containing polypropylene, glass and carbon fibres, respectively. Statistical analyses (ANOVA) were carried out to assess the impact of fibre content on the mechanical properties of mortars. Brittle fracture toughness was also tested using the Cracked Straight Through Brazilian Disc method. The addition of each type of fibre improved the assessed parameters. Based on the obtained research results, and also due to availability and price, the most advantageous seems to be the production of composites containing the addition of polypropylene fibres.

The file attached to this record is the author's final peer reviewed version. The engineering of advanced healthcare materials provides a platform to address challenges facing interdisciplinary scientists, clinicians, pharmacists, biomaterial scientists and biomedical engineers. Niche and timely developments arising from the synthesis or extraction of more biocompatible materials, new biologically active components, clearer insights into disease mechanisms and novel therapies or strategies provide several timely opportunities. These include enhanced therapies with greater patient compliance, improved disease targeting, better diagnosis and bespoke medications for individuals. Electrohydrodynamic atomisation (EHDA) engineering comprises several processes making use of electric fields (e.g. through an applied voltage) interplaying with several forces (e.g. gravity and surface tension). Coupled to advanced materials (e.g. formulated media) and specifically configured apparatuses (e.g. nozzles, collectors and downstream processes); effective and controlled fabrication of various structures (fibers, particles, bubbles, grids, droplets) on various scales (macro, micro and nano) possessing various dimensions (2D, 3D and 4D) is readily achieved. The processes have distinct advantages compared to established engineering methods (ambient environment engineering, low shear, scalability, compartmentalisation etc.). This detailed review focuses on key concepts and developments in EHDA engineering pertaining to underlying principles, enabling tools and engineered structures specifically for healthcare remits. From initial experiments involving the behaviour of non-formulated liquids on charged amber to recent developments in complex 3D matrix printing; the EHDA route has progressed significantly, most rapidly in the last two decades, and is capable of providing timely platform opportunities to tackle several global healthcare challenges

We develop a novel apparatus and a n associated test protocol to measure the tensile response of materials. The apparatus allows testing of ring - shaped specimens , fibre yarns and tapes of arbitrary length ; it can be employed to conduct experiments at different strain rates and in different environmental conditions . The technique is tested at low rates of strain on several materials, including carbon fibres, metals, polymers and ceramics ; the tensile respon ses measured with the new apparatus are compared to those obtained from conventional measurements and found to be in good agreement with these .

Biomaterials processed in the form of electrospun fiber mats have already been explored to mimic different types of extracellular matrix in the human body once human body shows both aligned and randomly oriented cell/tissues. Knowing that numerous cell functions are regulated by mechanical signals, it is of key importance to quantitatively taken into account the influence of the fiber alignment on the tensile properties of such biomaterials as they will determine suitability of the materials for specific applications. In this way, this work reports on the development of nano-engineered poly(vinylidene fluoride) (PVDF) aligned and randomly oriented fibers and in the influence of fiber orientation on their mechanical properties. It was found that the Young's modulus depends significantly on the angle between the stretch direction and the fiber direction (225 MPa, 27 MPa and 23 MPa for the 0°, 45° and 90° angles, respectively), being independent of the deformation direction on the randomly oriented fibers. Nevertheless, with the applied stress, all samples undergo a reorientation of the fibers towards the stretching direction and a decrease of the fiber diameter. The addition of CoFe2O4 magnetostrictive nanoparticles, that induces the magnetoelectric response on the composite fiber mats and opens large application potential for non-contact tissue engineering strategies, slightly changed the Young's Modulus of the fibers (increased to 308,71 MPa for the sample with 10 wt% of CoFe2O4). All the features allied with the non-cytotoxicity of the developed composite fibers makes them good candidates for scaffold in tissue engineering applications., MINECO -Eusko Jaurlaritza(MAT2016-76039-C4-3-R), info:eu-repo/semantics/publishedVersion

The change in stiffness with temperature in the presence of different media has been discussed for a long timebecause the ability to predict this behavior becomes fundamental to the design of new materials and their applications. That is why,in this work, the application of a mathematical model, which is able to predict the elastic properties of two polymers, is presented.The study takes into account the relationship between the viscoelastic and absorption properties of these materials in alkalinesolution (Ca (OH)2, pH 12.5) and in distilled water (H2O, pH 7) as the immersion media. Diffusion coefficient values were higherwhen the resins were immersed in water than in the alkaline solution. In addition, the effect of the alkaline medium was higher forthe unsaturated polyester resin (UPR). The highest decrease in modulus at the glassy state of the polymer network was observed forthe UPR immersed in the alkaline medium. The greatest reduction of the Tg value due to network plasticizing was found for theepoxy resin (ER) in the alkaline medium. Therefore, the ER exhibited a more stable behavior after aging at moderate temperaturethan the UPR. Fil: Morales Arias, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentina Fil: Bernal, Celina Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentina Fil: Vázquez, Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentina Fil: Escobar, Mariano Martin. Instituto Nacional de Tecnología Industrial; Argentina

Different summation methods of multidimensional trigonometric Fourier series are adopted for approximating the local strain and stress in elastic periodic composites. In fact, approximating the exact solution of a problem with the original partial sums of Fourier series can produce unwanted effects, such as the Gibbs phenomenon at the jump discontinuities that may occur at the interface between the constituents of the composites. Nevertheless, the Fourier coefficients of the original partial sums contain enough information to provide better estimates via the summability methods. In the means provided by the summability methods, the Fourier coefficients are suitably weighted by reducing windows, involving a regularization of the numerical solution. First, a complete solution method is used in order to determine some Fourier coefficients of the local strain in periodic composites. Next, these Fourier coefficients are used to construct suitable summations and means exhibiting better convergence properties than those of the original partial sums of Fourier series. The proposed method, valid for a great variety of the geometry of the constituents embedded in the matrix, is here applied to unidirectional composites with cylindrical fibers. The behavior of the iterated Fejer partial sums, Fejer and Riesz means is investigated in order to improve the convergence, observing that the Riesz means have better convergence properties than those of the original partial sums of Fourier series.

Intraperitoneal cisplatin delivery has recently been shown to benefit ovarian cancer patients. Cisplatin-containing poly(lactide-co-glycolide) (PLGA) microspheres have been proposed for cisplatin delivery. The drug loading of cisplatin containing microspheres produced elsewhere is 3–10%w. Similar microspheres are reported here with a mean diameter of 38.8 µm, and a drug loading of 11.7%w, but using ethyl acetate as a safer solvent. In addition, novel formulations of cisplatin-containing solid and hollow PLGA 65:35 (lactide:glycolide) fibres were prepared and are reported here for the first time. PLGA hollow fibres were produced by phase inversion with a high drug loading of 27%w. Mechanistic mathematical models were applied to the cisplatin release profiles to allow quantitative comparison of microsphere, solid fibre and hollow fibre formulations. The diffusion coefficient of cisplatin eluting from a typical batch of PLGA microspheres was 4.8 × 10−13 cm2 s−1; this low diffusivity of cisplatin in microspheres was caused by the low porosity of the polymer matrix. The diffusion coefficients of cisplatin eluting from a batch of PLGA solid fibres and hollow fibres were 6.1 × 10−10 and 3.3 × 10−10 cm2 s−1, respectively. These fibres allowed the controlled release of high doses of cisplatin over four days and may represent an improvement in slow release technology for treatment of ovarian cancer.