Articles de revues : « Short C fibre »

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Ahmad, Husam, Jonas Stiller, Erik Päßler, Daisy Nestler, Guntram Wagner et Lothar Kroll. « Influence of Initial Fibre Length and Content Used in the Injection Moulding of CFRP on the Properties of C/C and C/C-SiC Composites ». Key Engineering Materials 809 (juin 2019) : 171–79. http://dx.doi.org/10.4028/www.scientific.net/kem.809.171.

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The production of C/C-SiC composites comprises a three-stage process: forming (CFRP-composite), pyrolysis (C/C-composite) and liquid silicon infiltration (C/C-SiC). A new promising approach for the manufacturing of CFRP intermediate composites is the injection moulding of customised granulates (novolac resin, hardener, processing additives and short carbon fibre) produced by compounding technique. To date, a direct dosing of short carbon fibre into the compounder was technically not realisable due to fibre separation and electrostatic charging in the hopper. A possible substitute solution has been the direct feeding of a carbon fibre bundle from a roving into the compounder. However, this is associated with a severe damage of the fibres and an inaccurate adjustment of the fibres content. In the present article, new chopped carbon fibres provided with an adapted sizing to be directly dosed into the compounder are used. The fibres possess a predefined length of 3 and 6 mm and their content amounts to 50 and 58 wt.%. The influence of the initial fibre length and fibre content on the physical and mechanical properties of the resulting CFRP-, C/C-and C/C-SiC-composites is presented and discussed. In addition, the impact of fibre feeding procedure at the compounding stage on the microstructure is considered

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Shibata, Mitsuhiro, Retsu Makino, Ryutoku Yosomiya et Hiroyuku Takeishi. « Poly(Butylene Succinate) Composites Reinforced with Short Sisal Fibres ». Polymers and Polymer Composites 9, n^o 5 (juillet 2001) : 333–38. http://dx.doi.org/10.1177/096739110100900504.

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Poly(butylene succinate) composites reinforced with short sisal fibre were prepared by melt mixing and subsequent injection moulding. The influence of fibre length, fibre content and the surface treatment of the natural fibres on the mechanical properties of the composites were evaluated. Regarding fibre length, the tensile and flexural properties of the composites had maxima at a fibre length of about 5 mm. The flexural and tensile moduli of the composites increased with increasing fibre content. Although the tensile strength hardly changed, the flexural strength increased up to a fibre content of 10 wt%. The dynamic mechanical analysis of the composites showed that the storage moduli at above ca.-16°C (corresponding to the glass transition temperature of the matrix) increased with increasing fibre content.

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Lee, Jae-Seol, et Toyohiko Yano. « Effect of Reinforcements on Mechanical and Thermal Properties of SiC Short-Fibre-Reinforced SiC Composites ». Advanced Composites Letters 13, n^o 4 (juillet 2004) : 096369350401300. http://dx.doi.org/10.1177/096369350401300403.

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Tyranno SA fibre was higher strength at high temperatures and higher thermal conductivity than that of Hi-Nicalon fibre. Therefore, the aim of this study was to investigate the effect of reinforcements on the mechanical and thermal properties of SiC/SiC composites containing non-coated Tyranno SA short fibres. SiC/SiC composites containing 30 vol.% short fibres were fabricated by tape-casting and hot-pressing at 1650°C–1750°C under a pressure of 40 MPa using an Al2O3-Y2O3-CaO mixture as sintering additives independent of fibre type.

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Fíla, Tomáš, Petr Koudelka, Daniel Kytýr, Jiri Hos et Jan Šleichrt. « Creep behaviour of a short-fibre C/PPS composite ». Materiali in tehnologije 50, n^o 3 (17 juin 2016) : 413–17. http://dx.doi.org/10.17222/mit.2014.208.

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Hausherr, J. M., M. Eitel et W. Krenkel. « Determination of material properties for short fibre reinforced C/C-SiC ». MATEC Web of Conferences 29 (2015) : 00005. http://dx.doi.org/10.1051/matecconf/20152900005.

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Mohammed, Abdullahi Ali, Ramadhansyah Putra Jaya, Étienne Joseph Marie Delbrel, Choong Wee Kang, Sien Ti Kok, Haryati Yaacob, Norhidayah Abdul Hassan, Nor Hayati Abdul Hamid et Noram Irwan Ramli. « Stiffness Modulus of Asphaltic Concrete Incorporating Coir Fibre and Subjected to Aging ». E3S Web of Conferences 65 (2018) : 02003. http://dx.doi.org/10.1051/e3sconf/20186502003.

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The aim of this paper is to investigate the performance response of a set of coir fibre modified asphalt samples subjected different ageing conditions and containing three different fibre contents. The laboratory experimental programs are indirect tensile test at 25°C and repeated load axial test at 40°C. The results showed that the fibres improved the mixture’s performance. The main findings obtained at 25°C for short and long-term ageing reveal that low fibre content at around 0.3% per aggregate weight display a stiffness modulus up to 14% higher than that of unmodified mixtures, hence showing that fibres may improve the bearing capacity and rut-resistance of asphalt mixtures. Conversely, as the amount of fibre increases to 0.5% and 0.7%, the stiffness decreases to the point of becoming unacceptably low, almost 80% lower than unmodified mixes stiffness. However the data also reveal that high fibre contents at 0.5% and above completely neutralize the impact of ageing on the mixture, indicating that fibre-modified mixtures would yield longer lives.

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Raether, Friedrich, Jürgen Meinhardt et Andreas Kienzle. « Oxidation behaviour of carbon short fibre reinforced C/SiC composites ». Journal of the European Ceramic Society 27, n^o 2-3 (janvier 2007) : 1217–21. http://dx.doi.org/10.1016/j.jeurceramsoc.2006.04.019.

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Ajukumar, Kodappully Anilan, Kumaraswamy Kaliamma Ajith Kumar, Kuriakkattil Kunjayyappan Ravikumar, Thazhavilai Ponnu Deva Rajan, Uma Thanu Subramonia Pillai et Bellambettu Chandrasekhara Pai. « Fabrication and Characterization of Short Carbon Fiber Reinforced AZ91 Mg Alloy Composites ». Materials Science Forum 710 (janvier 2012) : 347–52. http://dx.doi.org/10.4028/www.scientific.net/msf.710.347.

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Short carbon ﬁber reinforced AZ91 magnesium alloy matrix composites have been made by stir casting technique. The microstructure and the fibre matrix interfacial region of the composites characterized using optical and scanning electron microscopes reveal uniform distribution of fiber in the matrix and good interfacial bonding respectively. Increase in compressive strength values are observed with increase in fiber content where as the room and high temperature (150°C) strength properties are found to decrease marginally. The microfractograph of the tensile fractured surface reveals mixed type of fracture.

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Lin, Jeng-Shyong. « Effect of Heat Treatment on the Impact Strength of Glass Fibre Reinforced Polypropylene ». Polymers and Polymer Composites 10, n^o 8 (novembre 2002) : 607–18. http://dx.doi.org/10.1177/096739110201000804.

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The improvement of the interfacial adhesion of glass fibre reinforced polypropylene composites by heat treatment was studied. Polypropylene blended with short glass fibres was injection moulded. The moulded specimens were heat treated at various temperatures and for various times. Characterization of the mechanical properties of the samples was performed, including measurement of the critical fibre length. Impact tests were performed. The fracture surfaces were examined using a scanning electron microscope. The results show that the impact strength increased with the testing temperature. At 25°C, the impact strength was dominated by the fibre fracture mechanism. At temperatures above 120°C, it was strongly influenced by the PP matrix. At higher temperatures, the impact strength increased significantly because of the formation of extra cracks.

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Nier, Natalia, Erik Päßler, Julia Weißhuhn, Kristina Roder, Daisy Nestler, Lothar Kroll, Stefan Spange et Guntram Wagner. « Evaluation of the moulding process for production of short-fibre-reinforced C/C-SiC composites ». Journal of the European Ceramic Society 40, n^o 4 (avril 2020) : 1057–66. http://dx.doi.org/10.1016/j.jeurceramsoc.2019.12.020.

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Sabiston, Trevor, Bin Li, Waqas Muhammad, Jidong Kang et Carlos Engler-Pinto. « The Role of Fibre Length on the Fatigue Failure of Injection-Moulded Composites at Elevated Temperatures under a Range of Axial Loading Conditions ». Journal of Composites Science 6, n^o 2 (20 janvier 2022) : 38. http://dx.doi.org/10.3390/jcs6020038.

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The effect of fibre length distribution on the fatigue behaviour of an injection-moulded PA66 carbon fibre composite is investigated. Two materials, short carbon fibre with a mean length of 100 microns, and long carbon fibre with a mean length of 580 microns, are subjected to fully reversed fatigue loading at room temperature and three stress ratios at 120 °C. The fatigue results are compared, and fracture surfaces are analyzed to determine the differing failure modes between the materials and loading conditions. At 120 °C, the fibre length has a significant effect on the fatigue behaviour with order of magnitudes of different fatigue life for a given stress amplitude during tensile fatigue loading. Under tensile loading, fatigue failure initates as fibre matrix debonding with pits present due to end effects in the short carbon fibre material. Under compression–compression loading, the fatigue life is matrix-dominated and should be treated as a maximum stress failure. Under this loading, a smooth crack propagates across the sample with buckling as the final failure mode.

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Nestler, Daisy, Natalia Nier, Kristina Roder, Erik Päßler, Julia Weißhuhn, Andreas Todt, Hendryk Würfel et al. « Development and Characterisation of Phenolic Resin Moulding Materials for the Production of New Short Fibre-Reinforced C/C-SiC Composites ». Materials Science Forum 825-826 (juillet 2015) : 215–23. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.215.

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This article focuses on the development of phenolic resin moulding materials for the production of new carbon fibre-reinforced ceramic composite materials based on C/C-SiC by utilising the LSI (liquid silicon infiltration) production method. The production of these moulding materials is being accomplished by combining phenolic resin and carbon fibres with the addition of a few selected parts of processing aids, during which the influence of the used lubricants on the processability of the moulding materials is examined. The starting materials, microstructures and mechanical properties of the materials were characterised at every step of the entire process (CFRP and C/C composites) as well as the end of the whole production (C/C-SiC composites). During this investigation a link between the portions of the lubricant used, the forming of the porosity and the impact on the mechanical properties was discovered. In regards to the optimisation of the process the involved parties were able to determine an optimal lubricant ratio.

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Caballero-Jorna, Marta, Marta Roig-Flores et Pedro Serna. « Effect of short-term exposure to moderate temperatures on the residual strength of cracked fibre reinforced concretes ». MATEC Web of Conferences 361 (2022) : 05013. http://dx.doi.org/10.1051/matecconf/202236105013.

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This work studies the effect of short-term exposure to the temperatures of -15°C, 5°C, 40°C and 60°C on the flexural performance of Fibre Reinforced Concretes (FRCs) with steel and synthetic fibres in cracked conditions. The results will be compared with the performance in cracked conditions at 20°C (submerged and air environments). The content of the fibres was chosen to guarantee similar residual strength in all the mixes. The beams were pre-cracked following EN 14651 at ambient temperature after 28 days, up to a crack mouth opening displacement (CMOD) of 0.5 mm. Afterwards, these beams were exposed for 3 days to moderate temperatures, and they were re-loaded up to failure maintaining the target temperature during the test. The residual strength at CMODs of 1.5, 2.5 and 3.5 mm was analysed. Concrete mixes were also characterised by compressive strength, air content, fresh density, and workability. The results show that residual strengths of cracked FRC are more sensitive to sub-zero temperatures than to warm temperatures, similar to the behaviour of uncracked specimens. Synthetic and steel FRCs presented enough flexural response after short-term exposure to moderate temperatures under cracked conditions.

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Tembe, E. T., David Oriabure Ekhuemelo et B. T. Aondoaver. « ASSESSMENT OF FIBRE CHARACTERISTICS OF SPONDIA MOMBIN L. (ANACARDIACEAE) FOR PULP AND PAPER PRODUCTION ». FUDMA JOURNAL OF SCIENCES 5, n^o 1 (29 juin 2021) : 511–16. http://dx.doi.org/10.33003/fjs-2021-0501-597.

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The fibre characteristics of five Spondia mombin stands were studied to determine their suitability for pulp and paper production. Wood slivers obtained parallel to grain at three (3) different positions along the bole were macerated in combined identical amounts of glacial acetic acid plus hydrogen peroxide under heat at between 80-100o C. Macerated fibres were washed clean of mixture and mounted on slide for microscopic examination of fibre characteristics. Completely Randomized Design (CRD) was employed for the experiment. Data were analysed using one-way Analysis of Variance (ANOVA) while, the Duncan’s Multiple Range Test (DMRT) was used to separate means of significant differences among the treatments. Results show that significant differences existed in fibre characteristic of sampled trees, however the fibre length ranged from 0.98-1.0 mm, fibre diameter (18.22-21.47 um), lumen width (10.90-12.98 um) and cell wall thickness (3.86-4.60 um). Significant differences were also observed among the derived fibre characteristics, the Runkel ratio ranged from 0.66-8.89, elasticity coefficient (57.22-60.50 %), coefficient of rigidity (19.78-22.24 %), slenderness ratio (43.27-46.5). This implied that, the fibres of S. mombin were short and elastic which make the wood species an appropriate raw material for pulp and paper making especially when blended with other long fibre species.

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Wydra, Małgorzata, Piotr Dolny, Grzegorz Sadowski et Jadwiga Fangrat. « Flexural Behaviour of Cementitious Mortars with the Addition of Basalt Fibres ». Materials 14, n^o 6 (10 mars 2021) : 1334. http://dx.doi.org/10.3390/ma14061334.

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The results of flexural tests of basalt fibre-reinforced cementitious mortars in terms of flexural strength and the occurrence of the bridging effect are summarised. Mixture proportions and curing conditions were altered for various series. The main parameters concerning mixture proportions were water to cement ratio (w/c), micro-silica and plasticiser addition and fibre dosage (1%, 3% and 6.2% by binder’s mass). Various curing conditions were defined by different temperatures, humidity and time. The influence of the amount of water inside the pores of the hardened cementitious matrix on the flexural strength values, as far as the impact of the alkaline environment on basalt fibres’ performance is concerned, was underlined. The designation of flexural strength and the analysis of post-critical deformations were also performed on the reference series without fibres and with the addition of more common polypropylene fibres. The bridging effect was observed only for the basalt fibre-reinforced mortar specimens with a relatively low amount of cement and high w/c ratio, especially after a short time of hardening. For the lowest value of w/c ratio (equalling 0.5), the bridging effect did not occur, but flexural strength was higher than in the case of non-reinforced specimens. Comparing mortars with the addition of basalt and polypropylene fibres, the former demonstrated higher values of flexural strength (assuming the same percentage dosage by the mass of the binder). Nevertheless, the bridging effect in that case was obtained only for polypropylene fibres.

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Murčinková, Zuzana, Przemysław Postawa et Jerzy Winczek. « Parameters Influence on the Dynamic Properties of Polymer-Matrix Composites Reinforced by Fibres, Particles, and Hybrids ». Polymers 14, n^o 15 (28 juillet 2022) : 3060. http://dx.doi.org/10.3390/polym14153060.

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In this paper, we present an extensive experimental study on the dynamic mechanical properties of composites with polymer matrices, as well as a quantification of the parameters that influence these properties. Polymer-composite matrices make it possible to form any reinforcement arrangement of fibres, particles, and layers, which makes it possible to form composite materials with certain dominant mechanical properties according to the internal arrangement for the application. In this study, we focused on the dynamic properties (i.e., damping parameters, such as the loss factor (tan d), logarithmic decrement (λ), storage modulus (E′), and loss modulus (E″)) of composites with polymer matrices, including parameters such as the fibre material, fabric weaving, fibre orientation, temperature, frequency, particle size, volume of short fibres, and epoxy resin type. If other articles focus on one type of composite and 1–2 parameters, then the benefit of this article lies in our analysis of 8 mentioned parameters in the experimental analysis of 27 different types of composites with polymer matrices. The tested fibre materials were glass, aramid, and carbon; the tested woven fabrics were twill, plain, unidirectional, and satin; the temperature range was from −50 to +230 °C; the frequency was 1 Hz and 10 Hz; the particle size was 0.1–16 mm; the volume percentages of the short fibres were 3, 6, and 12 vol.% of the hybrid polymer composites and the type of polymer matrix. We used the free-damped-vibration method with vibration dynamic signal analysis and the forced-damped vibration of dynamic mechanical thermal analysis for testing. We ranked the parameters that influence the dynamic vibration properties according to the effects. Among sets of results provided in the paper, considering the storage modulus, loss modulus, and loss factor, the best results of the fibre composites were for aramid-fibre-reinforced polymers, regardless of the weave type, with an advantage for unidirectional fabric. The best results of the particle composites were for those with fine filler sizes that incorporated the short fibres.

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Stiller, Jonas, Daisy Nestler, Erik Päßler, Fabian Kempe, Hendrik Wätzig, Husam Ahmad, Lothar Kroll, Michaela Sommer et Guntram Wagner. « Modification of the Thermoset Injection Moulding Process for Shaping to Increase the Fibre Length in C/C-SiC Ceramics Produced by the LSI Process ». Key Engineering Materials 809 (juin 2019) : 153–60. http://dx.doi.org/10.4028/www.scientific.net/kem.809.153.

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Ceramic-matrix composites (CMC) made of carbon and silicon carbide dual matrix reinforced with carbon fibres (C/C-SiC) have exceptional heat, thermal shock, creep, and wear resistance, while also having little density and high strength. In comparison to monolithic ceramics, CMC possess ductility and damage tolerance, which opens this material for severe applications. Starting in space applications, this material is today well established in friction applications, where lightweight high-performance brakes securely decelerate e.g. luxury cars or elevators. The high production costs still limit the broad application like as brake discs in standard passenger cars, although less weight, better performance and longer lifetime. The industrial used production process is the liquid silicon infiltration (LSI) with it three steps: green body shaping, pyrolysis and silicon infiltration. In this work, the shaping process of the carbon fibre reinforced plastic (CFRP) green body, is done by thermoset injection moulding. The application of plastic production processes like compounding and injection moulding in the liquid silicon infiltration process route, enables large-scale manufacturing. However, the screws and high shear forces inside the plastic processing machines significantly shorten the fibres. This paper describes the pros and cons of thermoset injection moulding in the LSI route, as well as the development and effect of different reinforcement types in dependence of their fibre length, since several energy dissipation mechanisms bases on a minimum length of reinforcement fibres in CMC. Various raw materials like short and chopped fibres with different length, rovings, and different approaches to receive longer fibres and their outcomes are presented. The mechanical properties show promising values and the micrographs display the infiltration status and crack development inside the specimen.

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Peng, Xiao, Li Zhuan et Xiong Xiang. « The Microstructure and Tribological Properties of Carbon Fibre Reinforced Carbon/SiC Dual Matrix Composites ». Key Engineering Materials 434-435 (mars 2010) : 95–98. http://dx.doi.org/10.4028/www.scientific.net/kem.434-435.95.

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Carbon fibre reinforced carbon and silicon carbide dual matrix composites (C/C-SiC) are new type of high performance brake materials, and possess a series of outstanding advantages. In the present study, the C/C-SiC brake composites were fabricated by the combination of chemical vapor infiltration with liquid silicon infiltration. The fabric preforms were prepared by three dimension needling method. Results show the SiC form inside the short-cut fabric, around the needing fibre and among the fibre bundles in the non-woven web of the C/C-SiC composites. The average static friction coefficient of the C/C-SiC materials was 0.61. The average dynamic friction coefficient were between 0.41 and 0.54 with the increase of brake speed, and the wear rates are not sensitive to the brake speed and maintained about 0.02 cm3•MJ-1 all along.

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Wielage, Bernhard, Daisy Weber, Tobias Müller et Heike Steger. « Thermo-Mechanical Monitoring of Composite Materials during the Pyrolysis of C/C Composites ». Key Engineering Materials 425 (janvier 2010) : 95–105. http://dx.doi.org/10.4028/www.scientific.net/kem.425.95.

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Conventional mechanical and structural properties allow to describe the complete composite material. They do, however, not describe the reaction during the pyrolysis process. The dynamic mechanical thermal analysis (DMTA) is a technique which is used to characterize materials. In particular, the DMTA method is used to observe the viscoelastic nature of polymers. Another interesting application area of the DMTA is the simulation of pyrolysis experiments to obtain carbon/carbon composites (C/C composites). The pyrolysis process of carbon-fibre-reinforced plastics (CFRP) was performed by means of inert gas (Ar, ambient pressure) under a defined time-temperature profile or alternatively approached by short time sweeps in a DMTA. So the temperature dependence of the elastic modulus (E-modulus) and of the internal damping (tan δ) are determined starting from the cured carbon-fibre-reinforced plastic to the transformed C/C composites. The analyses were applied for different matrix resins. The shown method improves the access to usually hidden mechanical and structural properties and requires further investigation of the entire polymerization and pyrolysis processes.

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Ball, D., et I. A. Johnston. « Molecular mechanisms underlying the plasticity of muscle contractile properties with temperature acclimation in the marine fish Myoxocephalus scorpius ». Journal of Experimental Biology 199, n^o 6 (1 juin 1996) : 1363–73. http://dx.doi.org/10.1242/jeb.199.6.1363.

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Single fibres were isolated from the fast myotomal muscle of the short-horned sculpin (Myoxocephalus scorpius L.). Fish were acclimated to either 5 °C (10 h:14 h light:dark) or 15 °C (12 h:12 h light:dark) for 12 months. Isometric tension (Fmax) and unloaded contraction velocity (Vslack) were determined in maximally activated skinned fibres over the range 0 to 20 °C. Fibres isolated from 5 °C-acclimated and 15 °C-acclimated fish failed to relax completely following activations at 15 °C and 20 °C respectively. In 5 °C-acclimated fish, Fmax increased from 75 kN m-2 at 0 °C to 123 kN m-2 at 10 °C and was not significantly higher at 15 or 20 °C. The relationship between Fmax and temperature was not significantly different for cold- and warm-acclimated fish. Vslack was around 2.8 fibre lengths s-1 in both acclimation groups at 0 °C, but it increased at a significantly faster rate with temperature in 15 °C- than in 5 °C-acclimated fish. At 20 °C, Vmax was significantly higher in 15 °C-acclimated (8.7 fibre lengths s-1) than in 5 °C-acclimated fish (5.3 fibre lengths s-1). In order to investigate the molecular mechanism(s) underlying changes in Vmax, myosin was purified by ion-exchange chromatography. No difference in myosin heavy chain composition could be detected on the basis of peptide mapping with four different proteolytic enzymes. Two-dimensional polyacrylamide gel electrophoresis revealed no myofibrillar protein isoforms unique to either acclimation temperature. However, the ratio of myosin alkali light chain contents (LC3f:LC1f), as determined by capillary electrophoresis, was significantly lower in muscle from 15 °C-acclimated (0.73) than from 5 °C-acclimated fish (1.66). The results suggest that changes in Vmax are achieved via altered expression of myosin light chains independently of myosin heavy chain composition. In support of this hypothesis, the myofibrillar ATPase activity of fast muscle was not altered by temperature acclimation.

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Eriksson, Gunnar, et Urban Grén. « Pulp washing : Influence of temperature on lignin leaching from kraft pulps ». Nordic Pulp & ; Paper Research Journal 12, n^o 4 (1 décembre 1997) : 244–51. http://dx.doi.org/10.3183/npprj-1997-12-04-p244-251.

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Abstract The leaching of lignin from the fibre wall was studied in order to investigate the effects in the clean end of the fibre line. The focus was set on the short time intervals representative for the washing operation in industrial applications. The influence of temperature, pulp type and kappa number was investigated. It could be seen that there are different diffusivities for the soluble lignin in the wall at short and long time of leaching, probably due to the existence of a more open structure in an outer layer of the fibre wall, in which the lignin diffuses more easily and which is also emptied relatively fast, while diffusion of the lignin from the inner layers is significantly slower. There is also a relation between the leaching of sodium ions out of the wall and the short diffusion time of lignin, indicating a possible ion-ion interaction with the lignin in the outer layer of the fibre wall. The diffusivity of lignin increases more rapidly at temperatures above 80-90 "C. This temperature effect was confirmed in the results of wash test equipment experiments, giving noticeable differences above 100 "C. It was found that the experimentally determined lignin diffusivity differs for different kappa number and for type of pulp. The general behaviour of the phenomena, however, is the same.

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Hinz, Stephan, Jens Heidemann et Karl Schulte. « Damage Evaluation of GLARE®4B under Interlaminar Shear Loading at Different Temperature Conditions ». Advanced Composites Letters 14, n^o 2 (mars 2005) : 096369350501400. http://dx.doi.org/10.1177/096369350501400201.

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The fibre reinforced metal laminate GLARE®4B was investigated under interlaminar shear loading conditions at temperatures between −50°C and 110°C. Short beam shear (ILSS) and double notched shear (DNS) tests were performed. The interlaminar shear strength decreases strongly with increasing temperature. The DNS test shows that the shear strain increases and the interlaminar shear stiffness decreases with increasing temperature. The observed damage occurs mainly in the 90°-fibre layer. For low temperatures delamination between the fibre-layers is the dominant failure mode. The higher the temperature, the more cracks develop in the 90°-layers. These multiple cracks coalesce with increasing shear load and form the final fracture surface. Light and scanning electron microscopy showed that the cracks are mainly based on fibre-matrix interface failure.

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Trojanová, Zuzanka, et Zoltán Száraz. « Mechanical Properties of AS21 Magnesium Alloy Based Composites ». Materials Science Forum 482 (avril 2005) : 363–66. http://dx.doi.org/10.4028/www.scientific.net/msf.482.363.

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The high temperature behaviour of composites with the AS21 magnesium alloy matrix, reinforced by short Saffil fibres was investigated in the temperature interval from room temperature to 300 °C. The yield stress and the maximum stress decrease with increasing temperature. Two types of specimens were investigated – one with fibres plane oriented parallel to the stress axis and the other with perpendicular fibres plane orientation. Light and scanning electron microscopy were used for study of the microstructure of composites. Possible hardening and softening mechanisms are discussed. The shear stress at fibre/matrix interface was of greatest importance in this regard, though the contribution resulting from the dislocation density increase was also significant.

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Mubarak, Moawiah, Raizal Saifulnaaz Muhammad Rashid, Mugahed Amran, Roman Fediuk, Nikolai Vatin et Sergey Klyuev. « Mechanical Properties of High-Performance Hybrid Fibre-Reinforced Concrete at Elevated Temperatures ». Sustainability 13, n^o 23 (3 décembre 2021) : 13392. http://dx.doi.org/10.3390/su132313392.

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Deterioration of concrete’s integrity under elevated temperature requires an alteration in its composition to have better thermal stability. Fibre-reinforced concrete has shown significant improvements in concrete strength and this paper aimed to investigate the influence of steel (ST) and polypropylene (PP) fibres on the behaviour of high-performance concrete (HPC) exposed to elevated temperatures. Six mixtures were prepared and cast by adding one or two types of polypropylene fibre (54 and 9 mm) at 0.25 or 0.5% and either singly or in a hybrid combination, along with a fixed volumetric content at 1% of five-dimensional hooked steel (5DH) fibres. At the age of 28 days, samples were heated to the targeted temperature of 800 °C and cooled down naturally to the laboratory temperature. Visual inspection, flexural, split tensile and compressive strengths were examined before and after the exposure to elevated temperatures. Results exhibited that the hybridization of long and short PP fibres, along with the ST fibres, has notably improved all residual mechanical properties of HPC and kept the integrity of concrete after exposure to elevated temperatures. In addition, PP fibres can significantly prevent spalling, but ST fibres were ineffective in mitigating explosive spalling in beams specimens.

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Järvstråt, N. « An ellipsoidal unit cell for the calculation of micro-stresses in short fibre composites ». Computational Materials Science 1, n^o 3 (juillet 1993) : 203–12. http://dx.doi.org/10.1016/0927-0256(93)90012-c.

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Wang, Yiqiang, et Litong Zhang. « Tensile Behaviour and Damage Evolution of a C/SiC Minicomposite Fabricated by Chemical Vapour Infiltration ». Advanced Composites Letters 19, n^o 2 (mars 2010) : 096369351001900. http://dx.doi.org/10.1177/096369351001900203.

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The tensile behaviour of a C/SiC minicomposite fabricated by chemical vapour infiltration was examined and the associated damage evolution was monitored by using acoustic emission (AE) technique. The microstructure of minicomposite can be characterized by a uniformly thick SiC sheath, the thin fibre coatings, and large pores due to the tendency of fibres to cluster in the minicomposite. The load-displacement curves of minicomposite show a greatly nonlinear behaviour with four distinct regimes: initial self-alignment due to relaxation of fibres followed by preexisting microcrack extension, matrix macrocrack multiplication and then saturation. All these regimes can be well characterized by the corresponding AE activities. Therefore, it is believed that such experimental results would be beneficial to the optimization of processing conditions and derivation of parameters necessary for further modelling of the thermomechanical behaviours of real C/SiC composites with more complex architectures by fabricating minicomposites in a short time.

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Battancs, Emese, Tekla Sáry, Janka Molnár, Gábor Braunitzer, Máté Skolnikovics, Árpád Schindler, Balázs Szabó P., Sufyan Garoushi et Márk Fráter. « Fracture Resistance and Microleakage around Direct Restorations in High C-Factor Cavities ». Polymers 14, n^o 17 (25 août 2022) : 3463. http://dx.doi.org/10.3390/polym14173463.

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The aim of this research was to evaluate the mechanical impact of different direct restorations in terms of fracture resistance, and subsequent fracture pattern, in occlusal high C-factor cavities. Furthermore, the adaptation of different direct restorations in the form of gap formation was also evaluated. Seventy-two intact mandibular molars were collected and randomly distributed into three groups (n = 24). Class I occlusal cavities with standardized dimensions were prepared in all specimens. After adhesive treatment, the cavities were restored with direct restorations utilizing three different materials. Group 1: layered conventional packable resin composite (Filtek Ultimate), Group 2: bulk-fill resin composite (SDR), Group 3: bulk-fill short fibre-reinforced composite (SFRC; everX Posterior) covered with packable composite occlusally. Half of the restored specimens underwent static load-to fracture testing (n = 12/group), while the rest underwent sectioning and staining for microleakage evaluation and gap formation analysis. Fracture patterns were evaluated visually among the mechanically tested specimens. The layered composite restoration (Group 1) showed significantly lower fracture resistance compared to the bulk fill groups (Group 2, p = 0.005, Group 3, p = 0.008), while there was no difference in fracture resistance between the other groups. In terms of gap formation values, the layered composite restoration (Group 1) produced significantly higher gap formation compared to the bulk-fill groups (Group 2, p = 0.000, Group 3, p = 0.000). Regarding the fracture pattern, SFRC (Group 3) produced the highest number, while SDR (Group 2) produced the lowest number of repairable fractures. The use of bulk-fill resin composite (fibre or non-fibre-reinforced) for occlusal direct restorations in high C-factor cavities showed promising achievements regarding both fracture resistance and microleakage. Furthermore, the use of short fibre-reinforced bulk-fill composite can also improve the fracture pattern of the restoration-tooth unit. Bulk-fill materials provide a simple and effective solution for restoring and reinforcing high C-factor occlusal cavities.

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Wijayawardane, Isuru Sanjaya Kumara, Hiroshi Mutsuyoshi, Hai Nguyen et Allan Manalo. « Flexural behaviour of glass fibre-reinforced polymer and ultra-high-strength fibre-reinforced concrete composite beams subjected to elevated temperature ». Advances in Structural Engineering 20, n^o 9 (21 novembre 2016) : 1357–74. http://dx.doi.org/10.1177/1369433216677998.

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Composite beams consisting of pultruded glass fibre-reinforced polymer (GFRP) I-beams and ultra-high-strength fibre-reinforced concrete (UFC) slabs have been developed for use in short-span bridges. Fibre-reinforced polymer bolts (fibre-reinforced polymer threaded rods) and epoxy adhesive were used to connect the UFC slab to the GFRP I-beam. The authors conducted material tests and large-scale static bending tests at room and elevated temperatures (less than 90°C) to investigate the flexural behaviour of GFRP-UFC composite beams subjected to elevated temperature. The test results demonstrated that the mechanical properties of the GFRP I-beams, fibre-reinforced polymer bolts and epoxy adhesive were significantly deteriorated at elevated temperatures due to the glass transition of their polymer resin matrices. As a result, the stiffness and ultimate flexural capacity of the GFRP-UFC composite beams under elevated temperatures were significantly reduced. More than 85% of the flexural capacity of the GFRP-UFC composite beams was retained up to 60°C but that was decreased to 50% at 90°C. Fibre model analysis results confirmed that the stiffness of the GFRP-UFC composite beams is not significantly affected by actual hot environments, where there is a moderate temperature gradient across the beam cross-section.

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Lin, Jeng-Shyong, et Sheng-Kuen Wu. « Effect of Heat Treatment on the Fracture Toughness of Glass Fibre Reinforced Polypropylene ». Polymers and Polymer Composites 10, n^o 3 (mars 2002) : 211–18. http://dx.doi.org/10.1177/096739110201000303.

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In this work, the effect of heat treatment on the fracture toughness of glass fibre reinforced polypropylene was studied. Polypropylene blended with short glass fibres was injection-moulded. The moulded parts were heat treated at 150°C for 30 min. The crack growth resistance curve (R-curve) was measured to evaluate the effect of heat treatment on the fracture toughness, and to determine the stress intensity factor at the point of instability, KR(ins). The fracture surface was examined using scanning electron microscope to analyze the fracture mechanism. The results show that the stress intensity factor at the unstable fracture point KR(ins) increases with the initial crack length.

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Bavasso, Irene, Claudia Sergi, Teodoro Valente, Jacopo Tirillò et Fabrizio Sarasini. « Recycled Multi-Material Packaging Reinforced with Flax Fibres : Thermal and Mechanical Behaviour ». Polymers 14, n^o 20 (19 octobre 2022) : 4423. http://dx.doi.org/10.3390/polym14204423.

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In this work, the use of a recycled mix stemming from the treatment of multilayer aseptic packaging used in the food and beverage industry is proposed as the matrix for short fibre composites reinforced with flax fibres, to generate value-added materials in contrast to the more common end-of-life scenario including energy recovery. This is expected to be a preferred choice in the waste hierarchy at the European level. A commercially available material (EcoAllene) obtained from multilayer packaging recycling was compounded with short flax fibres up to 30 wt.% by twin screw extrusion, with a view to enhancing its poor mechanical profile and broadening its applications. Composites were in depth analyzed by thermogravimetric analysis and differential scanning calorimetry, which highlighted the complex nature of this recycled product, a limited nucleation ability of flax fibres and a lower thermal stability due to the premature degradation of natural hemicellulose and cellulose, though featuring in any case onset degradation temperatures higher than 300 °C. Composites’ mechanical properties were assessed in tension, bending and impact conditions, with remarkable improvements over the neat matrix in terms of stiffness and strength. In particular, at 30 wt.% fibre content and with 5 wt.% of maleated coupling agent, an increase in tensile and flexural strength values by 92% and 138% was achieved, respectively, without compromising the impact strength. The effectiveness of flax fibres confirmed by dynamo-mechanical analysis is beneficial to the exploitation of these composites in automotive interiors and outdoor decking applications.

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Bryan, Paul E., et Mark F. Green. « Low temperature behaviour of CFRP prestressed concrete beams ». Canadian Journal of Civil Engineering 23, n^o 2 (1 avril 1996) : 464–70. http://dx.doi.org/10.1139/l96-050.

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The corrosion of steel prestressing tendons exposed to deicing salts is increasingly becoming a significant problem in Canada. New fibre reinforced plastic (FRP) materials with high strength-to-weight ratios and noncorrosive characteristics are strong alternatives to solve this problem. Carbon fibre reinforced plastic (CFRP) is one of the most promising among available FRPs. Nevertheless, for CFRP rods to gain acceptance in Canada and other cold regions, their behaviour at low temperatures must be investigated. This paper describes an investigation of the feasibility of using CFRP LEADLINE rods to prestress concrete beams. The results of an experimental program on the short-term behaviour of CFRP prestressed concrete beams at low temperature (−27 °C) are discussed. A simple analytical model is used to predict the flexural response of CFRP beams at low temperature. The experimental results agree well with the analytical predictions. The behaviour of the CFRP tendons is shown to be unaffected by short-term exposure to this low temperature. Key words: carbon fibre, fibre reinforced plastic (FRP), advanced composite materials, prestressed concrete, low temperature, cold regions.

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El Bakkouri, Majida, Elena Seiradake, Stephen Cusack, Rob W. H. Ruigrok et Guy Schoehn. « Structure of the C-terminal head domain of the fowl adenovirus type 1 short fibre ». Virology 378, n^o 1 (août 2008) : 169–76. http://dx.doi.org/10.1016/j.virol.2008.05.011.

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Trojanová, Zuzanka, Zoltán Száraz, Pavel Lukáč, Zdeněk Drozd et Ján Džugan. « Strengthening and Thermally Activated Processes in an AX61/Saffil Metal Matrix Composite ». Crystals 10, n^o 6 (1 juin 2020) : 466. http://dx.doi.org/10.3390/cryst10060466.

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AX61 magnesium alloy was reinforced with short Saffil fibres using squeeze cast technology. Samples were cut from the casting in two directions: parallel and perpendicular to the fibre plane. Samples were deformed in compression at various temperatures from room temperature to 300 °C. Various strengthening mechanisms such as load transfer, increased dislocation density, Orowan and Hall–Petch strengthening were analysed. During deformation, the stress relaxation tests were subsequently performed. The relaxation curves were evaluated with respect to Li and Feltham equations with the aim to find stress components in matrix and parameters of the thermally activated process(es).

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Kestens, Leo, Ana Carmen C. Reis, Wlodzimierz Kaluba et Yvan Houbaert. « Grain Refinement and Texture Change in Interstitial Free Steels after Severe Rolling and Ultra-Short Annealing ». Materials Science Forum 467-470 (octobre 2004) : 287–92. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.287.

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A Ti-stabilized interstitial free steel was highly cold deformed to a reduction of 95% and subsequently submitted to extremely short annealing cycles with heating rates varying between 300°C/s and 4500°C/s followed by water quench at various temperatures. The microstructural and textural development was studied through various consecutive stages: partially recrystallized, fully recrystallized and after α→γ→α transformation. It was found that irrespective of the heating rate the recrystallization has completely terminated before the onset of the ferrite to austenite phase transformation. In the fully recrystallized condition, ultra-rapid heating gave rise to substantially refined structures with an average ferrite grain size of 6µm. It was also observed that this grain refinement saturates with heating rates beyond 1000°C/s. With regard to the texture formation, the characteristic {111} deep drawing fibre of cold rolled IF steels was observed, irrespective of the heating rate, in an annealing treatment as short as 0.3s. After the forward and reverse α→γ transformation, the ensuing ferrite texture displayed a strong memory effect, as the {111} fibre was even more intense after the double transformation than before.

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Mashri, M. O. M., Megat Azmi Megat Johari*, M. J. A. Mijarsh, Zainal Arifin Ahmad et Otman M. M. Elbasir. « Mechanical Behaviour of Normal Concrete using Fibre of Pine Tree Needle Leaves ». International Journal of Engineering and Advanced Technology 10, n^o 3 (28 février 2021) : 99–102. http://dx.doi.org/10.35940/ijeat.c2173.0210321.

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This research was carried out to study the behaviour of concrete, specifically flexural strength, by incorporating two types of pine needle leaves (green, and brown) recycled as fibre reinforcement in the concrete. The other goal of the study is to compare the two types of fibre and determine the maximum proportion of fibre to be added in the normal concrete. OPC concrete with 0%, 1% and 2% pine needle leaves fibre (green, and brown) was prepared based on the total weight of the mixture. At an ambient temperature of 28 ± 2°C, the specimens were checked for flexural strength (FS). Laboratory test results based on short term investigation reveals that the flexural strength of concrete containing brown pine fibre (BPF) is higher than that of Green pine fibre (GPF), and also higher than normal (OPC) concrete. The optimum proportion of pine needle leaf fibre is the brown fibre (fallen leaves) to be added in the concrete as fibre is 1% by the total weight of the mixture, which gave a positive reaction from the test that was performed.

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Godfrey, RW, S. Lorimer, S. Majumdar, E. Adelroth, PW Johnston, AV Rogers, SA Johansson et PK Jeffery. « Airway and lung elastic fibre is not reduced in asthma nor in asthmatics following corticosteroid treatment ». European Respiratory Journal 8, n^o 6 (1 juin 1995) : 922–27. http://dx.doi.org/10.1183/09031936.95.08060922.

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By morphometric investigation of the relative content of elastic and collagen fibres, we have tested the hypothesis that loss of elastic fibres in the conducting airways and lung parenchyma may reduce tissue elastic recoil, resulting in increased airway maximal closure and apparent increased responsiveness. The study groups comprised: Group A (n = 11) with relatively mild atopic asthma using inhaled bronchodilators prn (i.e. short-term corticosteroids users); Group B (n = 9) with more severe asthma requiring inhaled bronchodilators regularly, and daily inhaled glucocorticosteroids (i.e. longterm corticosteroid users); Group C (n = 12) normal healthy workers. Bronchial biopsy samples were taken from three sites from the left lung. Group A biopsy samples were taken before and after a 4 wk treatment period with inhaled corticosteroids (200 micrograms b.i.d.) and the relative elastic and collagen fibre content of a subepithelial zone was determined from electron micrographs. In a parallel study, the relative proportion of elastic fibre in post mortem lung tissue samples (inner aspect of the bronchial wall, alveolar wall, and points of attachment of surrounding alveoli to intrapulmonary bronchi) from subjects suffering a fatal asthma attack (n = 11), and non-asthmatic suffering sudden death (n = 9), were determined using Miller's elastic and eosin counterstain for light microscopy. In bronchial biopsies of normal subjects, 4.6 (SEM 1.1)% of subepithelial connective tissue was elastic fibre, similar to mild asthmatic subjects, 1.9 (SEM 0.48)%. Neither short-term (4 weeks) inhaled corticosteroid (200 micrograms b.i.d.) nor long-term (< 6 months) treatment with variable doses of inhaled steroids (100-1000 micrograms b.i.d.) significantly altered the elastic or collagen content of the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

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Bellier, R., et T. Gidenne. « Consequences of reduced fibre intake on digestion, rate of passage and caecal microbial activity in the young rabbit ». British Journal of Nutrition 75, n^o 3 (mars 1996) : 353–63. http://dx.doi.org/10.1079/bjn19960139.

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AbstractThe present work was undertaken to study in vivo fibre degradation, rate of passage and caecal fermentation activity (CFA) in the young rabbit (7 weeks old) receiving ad lib. a control (C) or a lowfibre (LF) diet (400 and 220 g neutral-detergent fibre (NDF)/kg respectively). As a consequence of the 50% reduction in the dietary fibre level, the voluntary food intake of the rabbits decreased by 25%, and the daily fibre intake was reduced by 60% (26·7 and 10·8 g NDF/d for groups C and LF, respectively).In spite of a longer mean retention time of the fibre particles, the quantity of fibre digested daily was significantly lower (P<0·01) for the LF than for the C group (4·0 and 7·8 g NDF/d respectively). The circadian distribution of the faecal excretion (as a percentage of the total DM output) did not differ between diets (P = 0·52) and no interaction was found (P = 0·96) between diet and time of excretion. Also, variables describing the CFA showed no interactions between diet (C or LF) and time of sampling (during caecotrophy or during hard faeces excretion). Our results indicated no direct relationship between the quantity of fibre digested and the total short-chain fatty acid concentration in the caecum, but the fermentation pattern indicated lower proportions of acetate for the LF diet. Higher levels of diaminopimelic acid (DAPA) and ATP were found for the LF diet associated with an improved dietary fibre digestibility, suggesting a higher microbial activity. However, this effect was balanced by a lower caecal digesta turnover rate and the microbial biomass output estimated through the faecal DAPA output did not vary significantly

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KARBHARI, V., et A. DOLGOPOLSKY. « Transitions between micro-brittle and micro-ductile material behaviour during FCP in short-fibre reinforced composites ». International Journal of Fatigue 12, n^o 1 (janvier 1990) : 51–56. http://dx.doi.org/10.1016/0142-1123(90)90342-c.

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Russell-Floyd, R. S., R. Johnson, R. G. Cooke et B. Harris. « Thermal-Shock behaviour of Short-Fibre Ceramic-Matrix Composites Made by the Freeze-Gelation Process ». Advanced Composites Letters 2, n^o 2 (mars 1993) : 096369359300200. http://dx.doi.org/10.1177/096369359300200204.

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This paper discusses the effect of thermal shock on the mechanical properties of some ceramic matrix composites manufactured by the sol-gel process. The composites were prepared by the freeze-gelation of aqueous sols of two different matrix compositions, each containing about 10vol% of Saffil alumina fibres. The properties of one composite remained almost unaffected by the thermal shock, while those of the second material remained unaffected up to about 300°C and then fell smoothly as the water-quenching temperature was further increased to 600°C.

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KORNHUBER, M. E., et C. WALTHER. « The Electrical Constants of the Fibres from Two Leg Muscles of the Locust Schistocerca Gregaria ». Journal of Experimental Biology 127, n^o 1 (1 janvier 1987) : 173–89. http://dx.doi.org/10.1242/jeb.127.1.173.

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1. The passive electrical properties of the fibres from the M. extensor tibiae and the M. retractor unguis in the hindleg of the locust Schistocerca gregaria were investigated using short cable theory. The dependence on various physicochemical parameters was determined. 2. The sarcoplasmic resistivity (R1) was the same in the extensor and in the retractor muscle. R1 was ≊ 175 Ωcm at 20°C. 3. The specific membrane resistance (Rm) was considerably lower in the retractor muscle (≊5100 Ωcm2) than in the extensor muscle (≊13 000 Ωcm2; [K+]o =; 10 mmoll−1; temperature = 20°C). Rm increased by more than 100 % if the external potassium concentration was lowered from 10 to 5 mmoll−1 and it decreased by approximately 75 % if the calcium concentration was lowered from 2 to 0.2 mmoll−1. 4. The specific membrane capacity (Cm) increased with fibre diameter. The different mean values for Cm in the extensor (8.5 μF cm−2) and retractor muscle (6.3 μF cm−2) can be accounted for by the different mean fibre diameters. 5. The temperature coefficients (Q10) of the electrical constants were 0.74 for Ri, 0.48 for Rm, 1.01 for Cm and 1.21 for the resting membrane potential (temperature, 16–27°C). 6. There was close agreement between the membrane time constant (τm) derived from the decay of the excitatory junction potential (EJP) and that derived from injection of current pulses. Thus Rm and the length constant (λ) can be derived from the EJP and the fibre diameter if the sarcoplasmic resistivity and the specific membrane capacity are known. 7. The temporospatial dependence of miniature EJPs in a fibre can be predicted satisfactorily from the electrical constants as is demonstrated by an example given in the Appendix. Note: Dedicated to the late Graham Hoyle

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Anjos, Ofélia, António J. A. Santos, Rogério Simões et Helena Pereira. « Morphological, mechanical, and optical properties of cypress papers ». Holzforschung 68, n^o 8 (1 décembre 2014) : 867–74. http://dx.doi.org/10.1515/hf-2013-0125.

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Abstract The pulping properties of cypress species are not known and the present paper aims to filling this gap. Namely, Cupressus lusitanica Mill., C. sempervirens L. and C. arizonica Greene have been submitted to kraft pulping and the pulp properties are compared with those of Pinus pinaster Aiton. and P. sylvestris Watereri as references. Schopper Riegler degree, density, Bekk’s smoothness, tensile index, tear index, burst index, stretch, dry zero-span strength, wet zero-span strength, brightness, opacity and light scattering coefficient have been tested. The pulp yields and delignification degrees of cypress woods were lower than those of the pine references. Fibre length, width and coarseness were statistically different between pines and cypress species and C. sempervirens pulps have corresponding data close to those of pine species. Cypress pulps can be refined much faster than pine pulps. The papers sheets of cypress fibres have, in general, lower mechanical performance than those of pine fibres. Papers from C. arizonica and C. lusitanica are similar and C. sempervirens has intermediate properties being between the other cypress and pine species. However, cypress fibres are relatively short, flexible and collapsible and can be refined with low energy demand, and thus could be incorporated into papers resulting in products with better light scattering and smoothness.

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Majid, M. S. Abdul, Mohd Afendi, R. Daud, N. A. M. Amin, Azizul Mohamad et M. Hekman. « The Interlaminar Shear Strength Test of Helical Wound Glass Fibre Reinforced Epoxy Laminates Subjected to Hydrothermal Ageing ». Applied Mechanics and Materials 554 (juin 2014) : 391–95. http://dx.doi.org/10.4028/www.scientific.net/amm.554.391.

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This paper presents the experimental investigation of interlaminar shear strength (ILSS) tests of helical wound glass fibre reinforced epoxy (GRE) pipes subjected to hydrothermal ageing. Currently, the test is being used by composite pipes manufacturers as the alternative internal quality monitoring program for detection of manufacturing changes and reconfirmation of the design basis of composite pipes. The test specimens were cut in hoop direction from helically wound GRE composite pipes after exposure of 0, 250, 500, 1000-hour water at 80°C. The ILSS tests of the GRE samples were then conducted in accordance with ASTM D2344, and the results were analyzed to evaluate the durability performance of the laminates. The results show a clear degradation in the bonding strength between fibres and resin system interface after 500-1000-hour water exposure at 80°C. This findings show a good agreement in the trend observed with the standard qualification procedure elucidated in ASTM D2992 standard. Hence, ILSS test shows a great potential to be used as the internal short-term mechanical test method to qualify a new resin, curing agent or glass fibre in accordance to the next approach.

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Isobe, W., S. Murakami, T. Saito, S. Kumagai et M. Sakita. « Effect of aerobic exercise on muscle structure and expression of proteins promoting hypertrophy and metabolism in aged rats ». Comparative Exercise Physiology 16, n^o 5 (20 octobre 2020) : 377–85. http://dx.doi.org/10.3920/cep190077.

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Aging and physical inactivity lead to histochemical changes in muscles. The expression of many muscle proteins, including brain-derived neurotrophic factor (BDNF), silent information regulator of transcription 1 (SIRT1), and peroxisome proliferator-activated receptor γγ coactivator-1α (PGC-1a), declines with age. However, the effect of aerobic exercise on muscle structure and the expression profile of these proteins in elderly rats is unknown. Here, we investigated whether short-term aerobic exercise improves muscle structure and increases BDNF, SIRT1, and PGC-1a levels in aged rats. Ten male Wistar rats (95-week-old) were assigned to sedentary (SED) or exercise (Ex) groups. The Ex group performed running on a treadmill for 1 h, 6 times per week, for 2 weeks. The extensor digitorum longus muscles were removed to examine the muscle fibre type composition, cross-sectional area, and capillary-to-fibre (C/F) ratio. BDNF, SIRT1, and PGC-1a levels were evaluated by western blotting. Relative to the SED group, the Ex group showed increased proportion of Type I fibres (P<0.05), cross-sectional area of all muscle fibre types (P<0.05), succinate dehydrogenase activity (P<0.001), C/F ratio (P<0.05), and expression of BDNF, SIRT1, and PGC-1a (P<0.05).Thus, 2 weeks of aerobic exercise is sufficient to improve muscle histology and hypertrophic marker protein expression, indicating that it could prevent skeletal muscle atrophy in elderly rats.

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Coste, J., DL Voisin, P. Luccarini et R. Dallel. « A Role For Wind-Up in Trigeminal Sensory Processing : Intensity Coding of Nociceptive Stimuli in the Rat ». Cephalalgia 28, n^o 6 (juin 2008) : 631–39. http://dx.doi.org/10.1111/j.1468-2982.2008.01568.x.

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Wind-up is a progressive, frequency-dependent increase in the excitability of trigeminal and spinal dorsal horn wide dynamic range (WDR) nociceptive neurons evoked by repetitive stimulation of primary afferent nociceptive C-fibres. The correlate of wind-up in humans is temporal summation, which is an increase in pain perception to repetitive constant nociceptive stimulation. Although wind-up is widely used as a tool for studying the processing of nociceptive information, including central sensitization, its actual role is still unknown. Here, we recorded from trigeminal WDR neurons using in vivo electrophysiological techniques in rats and assessed the wind-up phenomenon in response to stimuli of different intensities and frequencies. First, we found that the amplitude of C-evoked responses of WDR neurons to repetitive stimulation increased progressively to reach a peak, then consistently showed a stable or slightly decreasing plateau phase. Only the first phase of this time course fitted in with the wind-up description. Therefore, to assess wind-up, we measured a limited number of initial responses. Second, we showed that wind-up, i.e. the slope of the frequency-dependent increase in the response to C-fibre stimulation, was linearly correlated to the stimulus intensity. Intensities of brief C-fibre inputs were thus coded into frequencies of action potentials by second-order neurons through frequency-dependent potentiation of the evoked responses. Third, wind-up also occurred at stimulation intensities below the threshold for C-evoked responses in WDR neurons, suggesting that wind-up can amplify subthreshold C-fibre inputs to WDR neurons. This might account for the observation that sparse, subliminal, neuronal activity in nociceptors can become painful via central integration of neural responses. Altogether, the present results show that wind-up can provide trigeminal WDR neurons with the capability to encode the intensity of short-duration orofacial nociceptive stimuli and to detect subthreshold nociceptive input. Thus, not only may wind-up play a physiological role in trigeminal sensory processing, but its enhancement may also underlie the pathophysiology of chronic orofacial pain conditions.

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Das, Subhasis, et Anindya Ghosh. « Technique Based on Fuzzy Logic for Cotton Bale Lay-down Management ». Fibres and Textiles in Eastern Europe 25 (30 avril 2017) : 30–33. http://dx.doi.org/10.5604/12303666.1228163.

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In this paper a new technique has been proposed for cotton bale management using fuzzy logic. The fuzzy c-means clustering algorithm has been applied for clustering cotton bales into 5 categories from 1200 randomly chosen bales of the J-34 variety. In order to cluster bales of different categories, eight fibre properties, viz., the strength, elongation, upper half mean length, length uniformity, short fibre content, micronaire, reflectance and yellowness of each bale have been considered. The fuzzy c-means clustering method is able to handle the haziness that may be present in the boundaries between adjacent classes of cotton bales as compared to the K-means clustering method. This method may be used as a convenient tool for the consistent picking of different bale mixes from any number of bales in a warehouse.

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Sharma, S. C., M. Krishna, P. S. Vizhian et A. Shashishankar. « Thermal effects on mild wear transition in dry sliding of aluminium 7075-short glass fibre composites ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering 216, n^o 12 (1 décembre 2002) : 975–82. http://dx.doi.org/10.1243/095440702762508227.

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The unlubricated sliding high temperature wear behaviour of A17075 alloy composites reinforced with short E-glass fibre was evaluated. A17075-glass composites were prepared by the liquid metallurgical technique with 2, 4 and 6 per cent by weight. A high temperature sliding wear apparatus, with temperature range 30-200°C, was used to evaluate the wear rate. Results indicated that addition of short glass fibre to A17075 alloy not only delays the transition wear (transition between mild and severe wear) but also reduces the wear rate. However, in both unreinforced alloy and reinforced composites, the wear rates increased with increases in the load, operating temperature and sliding speed. Increase in the applied load and operating temperature increased the wear severity by changing the wear mechanism from adhesion wear to debris cracking induced delamination wear. The observations have been explained using scanning electron microscopy, X-ray diffraction and energy-dispersive spectroscopy analysis of the worn surfaces and the debris.

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Wang, J. F., Y. H. Zhu, D. F. Li, M. Wang et B. B. Jensen. « Effect of type and level of dietary fibre and starch on ileal and faecal microbial activity and short-chain fatty acid concentrations in growing pigs ». Animal Science 78, n^o 1 (février 2004) : 109–17. http://dx.doi.org/10.1017/s1357729800053893.

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AbstractA repeated 4 ✕ 4 Latin square design was conducted with eight ileal cannulated castrated pigs to investigate the effect of source of dietary fibre and starch on ileal and faecal microflora and short-chain fatty acid concentrations. Four experimental diets based on cooked rice were supplied with one of two fibre-rich sources (sugar-beet pulp, S; wheat bran, W) and another two diets were prepared with (P) or without (C) potato starch. The experimental periods were 14 days, consisting of 7 days of adaptation to each diet, followed by 4 days of collection of ileal digesta and 3 days of collection of faeces. Ileal digesta were collected daily in a randomized order 0 (just before feeding the morning meal), 2, 4, 6 and 8 h after feeding the morning meal. Fresh faecal samples were also collected. Ileal pH was lower in pigs given diet P, 2 and 4 h after feeding, respectively. For all four diets ileal pH reached a minimum 4 h after feeding. Faecal pH was higher for diets P and W compared with diets C and S. The highest density of ileal coliform bacteria was found 4 h after feeding for all diets. Compared with other diets, the inclusion of potato starch resulted in an increased density of ileal enterococci at 0 h and an increased density of ileal lactic acid bacteria and lactobacilli, 2 and 6 h after feeding, respectively. The density of ileal enterococci reached a maximum 4 h after feeding for all diets. With the exception of 8 h after feeding, when a higher density of total anaerobes was observed for diet P, no significant differences were seen in the populations of yeasts and total anaerobes between the experimental diets. The concentration of formate in the ileum was high, while low concentrations of acetate, propionate and butyrate were observed for all diets. A lowered level of acetate was found for diet S on all sampling occasions. On a dry-matter basis, the counts of various faecal bacteria were increased by the inclusion of the fibre sources, and a higher level of faecal butyrate was found with the inclusion of potato starch or the fibre sources as compared with diet C, whereas no significant effects on the counts of various bacteria were observed with potato starch supplementation. Overall, the present results indicate that the addition of dietary fibre to pig diets resulted in an enhanced microbial fermentation.

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Ong, Rachel, et Chun H. Wang. « Effect of Incipient Heat Damage on the Fatigue Properties of Aircraft Composites ». Advanced Materials Research 891-892 (mars 2014) : 1810–15. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1810.

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This paper presents a preliminary investigation into the effect of incipient heat damage on the mechanical properties of a carbon-epoxy composite. Specimens were exposed to a range of temperatures varying from 0°C to 280°C for one hour and then tested to quantify the effects of this high temperature exposure on the short-beam shear, Mode I and II interlaminar fracture toughness, and the Mode I fatigue properties. The results showed that as the exposure temperature increased, the short-beam shear suffered a reduction, whereas the Mode I and Mode II fracture toughness increased after an initial reduction. The fatigue disbond growth rates were largely un-affected under heat exposure below 280°C. This complex behaviour in the degradation in fracture toughness is likely due to the increased fibre bridging brought about by the reduction in matrix strength.

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Koráb, Juraj, Štefan Kavecký, Pavol Štefánik, Karol Iždinský, František Simančík et Tomáš Dvorák. « Microstructure and Thermal Expansion of Hybrid - Copper Alloy Composites Reinforced with both Tungsten and Carbon Fibres ». Materials Science Forum 782 (avril 2014) : 513–18. http://dx.doi.org/10.4028/www.scientific.net/msf.782.513.

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Tungsten as refractory material and high thermal conductive carbon fibres are promising candidates for production of copper matrix composites for high temperature applications. Three types of rod-like samples were prepared by gas pressure infiltration of different carbon/tungsten fibre preforms with copper and/or copper alloy (Cu-0.5Cr) respectively. The fibres are aligned parallel to rod axis and were combined with the tungsten wire cloth. The microstructure of prepared hybrid composites was examined. The samples were thermally cycled 3 times up to 550 °C at a relatively high heating/cooling rate (10 K/min) to touch real condition in applications where high heat is formed during short time. The thermal expansion behaviour in radial direction was also analysed. Results show that a combination of both types of reinforcements in rod-shapes samples insures good protection against composite disintegration during high temperature thermal loading.

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Scott, Paul, Eleni Toumpanaki et Janet M. Lees. « Solution Uptake in Cylindrical Carbon-Fibre-Reinforced Polymer (CFRP) Tendons ». Advances in Polymer Technology 2022 (30 novembre 2022) : 1–16. http://dx.doi.org/10.1155/2022/1981256.

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Salt water exposure conditions relevant to carbon-fibre-reinforced polymer (CFRP) prestressed concrete structures in marine environments are investigated. The diffusion into relatively small diameter CFRP tendons can be a lengthy process so the prediction of the long-term moisture uptake using short-term experiments on thin films of epoxy would be advantageous. However, the fibre inclusions within a composite introduce complexities, and factors are typically required for correlation with pure epoxy specimens. Diffusion parameters based on moisture uptake result from CFRP tendons exposed to salt water solution at 20°C and 60°C are compared with those obtained using equivalent thin film specimens. The higher temperature is selected to accelerate the moisture uptake. It is found that the measured ratios of tendon and epoxy diffusivity were temperature dependent, and the combination of the higher temperature and salt solution leads to an increased propensity for moisture uptake in the tendon. Existing analytical models to predict the CFRP tendon diffusivity from that of a thin film of epoxy did not appear to capture the observed trends. However, predictions using a unit cell with a fibre interface zone suggest that this may be due to an increased diffusivity in the interphase region.

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