Single Fiber Type Research Articles

Assessing rutting potential of stone mastic asphalt using wheel tracker and dynamic modulus testing

Rutting potential of stone mastic asphalt with varying aggregate gradations was assessed in the past mainly by uniaxial compression testing which is not the only test to predict its true performance in the field. Dynamic testing and accelerated wheel tracking test are considered the most suitable laboratory test procedures. Four stone mastic asphalt mixtures were prepared in this study using PG 58-22 binder, Viatop plus CT-40 fiber and four aggregate gradations with nominal maximum sizes of 9.5 mm, 12 mm, 19 mm and 25.4 mm. To access the effects of aggregate gradations, single type of bitumen, filler and fiber was used. Mixtures were tested and evaluated under both type of testing procedures at different temperature levels. A regression model was developed using wheel tracker test data to ascertain significant parameters that are directly influencing the rut depth. The statistics of the model shows an excellent degree of determinacy of 0.92 and a relative accuracy of 0.29. Sigmoidal functions using Witczak equations were determined from dynamic modulus master curves for characterization of mixes and compared with previous studies. Correlation between the wheel tracking factor and a dynamic modulus factor was also established at three frequency levels. The study reveals that a reasonable relationship exists between the wheel tracking factor and dynamic modulus factor for stone mastic asphalt mixtures

Development of deflection-hardening geopolymer-based ductile fibre reinforced cementitious composites

Ductile fibre reinforced cementitious composites (DFRCC) are cement-based composites reinforced with short random fibres (metallic and/or non-metallic) which exhibit deflection-hardening and multiple-cracking behaviours in bending. It is a special class of high performance fibre reinforced cementitious composite (HPFRCC) that has higher deflection capacity than that of regular fibre reinforced concrete (FRC). Current DFRCCs are limited to cement-rich matrix system. This paper reports the development of geopolymer-based DFRCC where the cement binder in DFRCC is replaced by fly ash-based geopolymer binder and alkaline liquids (sodium hydroxide and sodium silicate) are used to activate the fly ash. In this study, three types of fibres are considered namely steel and two types of polyvinyl alcohol (PVA) fibres having different diameter, length and elastic modulus. The fibres used in the development of both cement-based and geopolymer-based DFRCCs are limited to single fibre type. The effects of two different ...

Extension and validation of the GN model for non-linear interference to uncompensated links using Raman amplification

We show the extension of the Gaussian Noise model, which describes non-linear propagation in uncompensated links of multilevel modulation formats, to systems using Raman amplification. We successfully validate the analytical results by comparison with numerical simulations of Nyquist-WDM PM-16QAM channels transmission over multi-span uncompensated links made of a single fiber type and using hybrid EDFA/Raman amplification with counter-propagating pumps. We analyze two typical high- and low-dispersion fiber types. We show that Raman amplification always induces a limited non-linear interference enhancement compared to the dominant ASE noise reduction.

Fibre composition of donated post-consumer clothing in the UK

At the end of life, post-consumer clothing in the UK either enters the municipal solid waste stream or is collected by way of an extensive network of clothing banks, charity shops and doorstep collections for recycling or reuse. This study reports the fibre/polymer composition of a large sample (n=34 635) of post-consumer clothing collected by The Salvation Army, one of the largest used clothing supply chain operators in the UK. The results revealed that 36·2% of the clothing items were of heterogeneous polymer composition, consisting of a blend or mixture of two or more fibre components; however, the largest fraction was composed of a single fibre type (excluding accessories and sewing threads). Cotton accounted for 54·7% of the total collected clothing and 22·6% was composed of polyester. There were no large geographical or collection source variations in terms of fibre compositions. A minimum economic recyclability index was approximated based on a potential value of fibre recyclate in post-consumer clothing that is currently directed to landfill.

Compressive Properties of Amorphous Metal Fiber Reinforced Concrete Exposed to high Temperature

Compressive property of high strength concrete with amorphous metal fibers subject to high temperature has been investigated. The measure of this investigation includes explosive spalling, weight loss, residual compressive strength, strain at peak stress, elastic modulus, and residual energy absorption capacity after exposure to <TEX>$400^{\circ}C$</TEX>, <TEX>$600^{\circ}C$</TEX>and <TEX>$800^{\circ}C$</TEX>. In addition to the amorphous metal fiber, two other types of fibers (polypropylene fiber and hooked-end steel fiber) were also included in this investigation for comparison. The experimental program was conducted with high strength concrete using several combinations of the fiber types. The testing result shows that the concrete with amorphous metal fibers plus polypropylene fibers shows a superior behavior than those using other combination or single fiber type ingredient.

Unusual and recently described cutaneous atrophic disorders

Cutaneous atrophic conditions are typically caused by changes in the dermis or subcutaneous tissue, sometimes consisting of the loss of a single fiber type. Since a significant decrease of subepidermal tissue is necessary for these lesions to be macroscopically atrophic, many conditions may not be appreciated as atrophy in the clinical setting. Clinicians should be familiar with the common or classic disorders causing cutaneous atrophy; however, there are a few new or rarely described atrophic conditions which are more difficult to identify and may not be atrophic clinically. This paper serves to describe the salient clinical and histological features of these new or rare disorders.

Mechanical Behavior of UHPC(&lt;i&gt;Ultra High Performance Concrete&lt;/i&gt;) According to Hybrid Use of Steel Fibers

This intends to examine the flexural behavioral characteristics of hybrid UHPC using a mix of steel fibers with different lengths. Three types of fibers are adopted with fixed diameter of 0.2 mm and lengths of 13, 16.3 and 19.5 mm (aspect ratio of 65, 82 and 98, respectively). Comparative analysis of the flexural strength, load bearing capacity, deflection and toughness is performed adopting a mix use of these 3 types of steel fibers with ratio of 2% and 1.5%. The results show that the hybrid use of steel fibers improves significantly the flexural strength and flexural toughness compared to the use of a single type of fiber. When steel fibers with lengths of 16.3 mm and 19.5mm are admixed at a rate of 1% each, UHPC develops a flexural strength larger by 27% (maximum 50%) than conventional UHPC admixed with 2% of steel fiber with length of 13 mm. Moreover, flexural strength similar to that of conventional UHPC is secured when steel fibers with lengths of 16.3 mm and 19.5mm are admixed at respective rates of 0.5% and 1% (total rate of 1.5%).

Solid-Phase Microextraction and the Human Fecal VOC Metabolome

The diagnostic potential and health implications of volatile organic compounds (VOCs) present in human feces has begun to receive considerable attention. Headspace solid-phase microextraction (SPME) has greatly facilitated the isolation and analysis of VOCs from human feces. Pioneering human fecal VOC metabolomic investigations have utilized a single SPME fiber type for analyte extraction and analysis. However, we hypothesized that the multifarious nature of metabolites present in human feces dictates the use of several diverse SPME fiber coatings for more comprehensive metabolomic coverage. We report here an evaluation of eight different commercially available SPME fibers, in combination with both GC-MS and GC-FID, and identify the 50/30 µm CAR-DVB-PDMS, 85 µm CAR-PDMS, 65 µm DVB-PDMS, 7 µm PDMS, and 60 µm PEG SPME fibers as a minimal set of fibers appropriate for human fecal VOC metabolomics, collectively isolating approximately 90% of the total metabolites obtained when using all eight fibers. We also evaluate the effect of extraction duration on metabolite isolation and illustrate that ex vivo enteric microbial fermentation has no effect on metabolite composition during prolonged extractions if the SPME is performed as described herein.

Effect of size and stacking of glass fibers on the mechanical properties of the fiber-reinforced-mortars (FRMs)

In modern day construction practice, repair and rehabilitation of structures have taken a prominent role. Indeed, the recent trend of rehabilitating and strengthening unreinforced masonry reinforced with glass fibers. In this paper, the use of fiber-reinforced-mortars (FRMs) is proposed for construction rehabilitation and reconstruction applications. A single type of fiber (glass fiber) with different length is considered; short, long and mixed. Several specimens mortars reinforced with fibers are tested in compression and flexure. Also, the stack and the microstructure of the interface glass fibers-matrix cementitious of the reinforced specimen, was examined. The results showed a remarkable increase in the mechanical resistances (50%), an important reduction of the brittleness of the reinforced mortars (lengthening higher than 40%) and a good ductility. That made it possible to increase considerably the safety of our constructions with a better esthetic aspect. Key words: Mortar, reinforcement, glass fibers, stackings, lengthening, mechanical properties.

다중이용시설 및 학교 교사내 실내공기중 섬유상 입자의 농도 특성

This study was investigated the characteristics of indoor air concentration of fiber particles in 30 public facilities and 245 schools by PCM (phase contrast microscopy). Also SEM/EDX (scanning electron microscope / energy dispersive using X-ray analysis) was used to obtain physicochemical information of asbestos fiber and to classify asbestos and non-asbestos of fiber particles. The airborne concentrations of fiber particles were counts/mL in public facilities and counts/mL in schools by PCM. All the samples were satisfied with the IAQ (indoor air quality) level of 0.01 counts/mL. In classification of 4 type shapes, over 80% of the fiber particles were identified as single fiber type. And this study analysed airborne fiber particles in 4 sites for identifying asbestos of by SEM/EDX. The asbestos fibers in most samples could not be found.

Variation in the determinants of power of chemically skinned human muscle fibres

We have explored the extent to which the maximal velocity of unloaded shortening (V(max)), the force generated per unit cross-sectional area (P(0)) and the curvature of the force-velocity relationship (a/P(0) in the Hill equation) contribute to differences in peak power of chemically skinned single fibres from the quadriceps muscle of healthy young male subjects. The analysis was restricted to type I and IIA fibres that contained a single type of myosin heavy chain on electrophoretic separation. Force-velocity relationships were determined from isotonic contractions of maximally activated fibres at 15 degrees C. Mean (+/- s.d.) peak powers were 1.99 +/- 0.72 watts per litre (W L(-1)) for type I fibres and 6.92 +/- 2.41 W L(-1), for type IIA fibres. The most notable feature, however, was the very large, sevenfold, range of power outputs within a single fibre type. This wide range was a consequence of variations in each of the three components determining power: P(0), V(max) and a/P(0). Within a single fibre type, P(0) varied threefold, and V(max) and a/P(0) two- to threefold. There were no obvious relationships between P(0) and V(max) or between P(0) and a/P(0). However, there was a suggestion of an inverse relationship between a/P(0) and V(max), the effect being to reduce, somewhat, the impact of differences in V(max) on peak power. In searching for the causes of variation in peak power of fibres of the same type, it appears likely that there are two factors, one that affects P(0) and another that leads to variation in both V(max) and a/P(0).

Influence of hygrothermal environment on thermal and mechanical properties of carbon fiber/fiberglass hybrid composites

The absorption and diffusion of water in a carbon fiber/glass fiber hybrid composite was investigated. Water-sorption experiments, mechanical property tests and dynamic mechanical analysis (DMA) were performed after immersion in water at different temperatures for up to 32 weeks. The moisture uptake mechanism exhibited by the hybrid fiber system was determined to be more complex than the single fiber type. Weight-change profiles for the composites fitted the theoretical Fickian diffusion curve during the initial immersion time, but diverged substantially as time progressed. The shear properties and the glass transition temperature ( T g) were sensitive to the effects of hygrothermal environment, and values for both decreased with increasing water uptake. Microscopic inspection of water-soaked samples showed no cracking when the absorption was less than saturation. The thermal and mechanical properties were mostly retained (after drying), provided the moisture absorption did not exceed the saturation point.

Single fiber physiology differs between three human leg muscles

While single fiber contractile function within a given fiber type population is largely similar between muscles, fiber type distribution can vary considerably. Because single fiber contractile function and fiber type distribution both contribute to whole muscle function, we generated composite profiles to compare three leg muscles of interest. Eight recreationally active males (5) and females (3) (23 ± 1 yr, 64 ± 3 kg, 51.8 ± 2.6 ml/kg/min) were biopsied from the vastus lateralis (VL) and soleus (S). To make further comparisons, seven recreationally active males (4) and females (3) (22 ± 1 yr, 68 ± 2 kg, 49.5 ± 2.6 ml/kg/min) were biopsied from the gastrocnemius (G). Single fibers were isolated and investigated for size and function, and subsequently processed for myosin heavy chain (MHC) composition (SDS‐PAGE). A composite value, which is a theoretical representation of the entire muscle, was then calculated for each contractile parameter based on the MHC composition of the studied fibers. The VL had higher specific tension (VL 66% &gt; G and 28% &gt; S), shortening velocity (40% &gt; G; 48% &gt; S), peak power (266% &gt; G; 152% &gt; S), and normalized power (276% &gt; G; 221% &gt; S), when compared to the gastrocnemius and soleus. Additionally, the gastrocnemius had lower peak tension (G 37% &lt; VL; G 31% &lt; S) and lower specific tension (40% &lt; VL; 22% &lt; S) when compared to the vastus lateralis and soleus. These findings highlight the unique intrinsic profile of these select muscles, which should be considered when interpreting how they adapt to exercise training.

Modeling and experimental verification of dielectric constants for three-dimensional woven composites

In order to determine the dielectric constants of 3D orthogonal woven single fiber type (SFT) and hybrid composites from their component dielectric properties, a theoretical model is proposed based on the rule of binary mixtures. The model shows that with the same fiber volume fraction, a component with a larger cross-sectional area perpendicular to the electric field has a greater contribution to the composite dielectric constant. For experimental verification, SFT basalt/epoxy and aramid (Kevlar 129)/epoxy as well as interply and intraply basalt/aramid/epoxy 3D orthogonal woven hybrid composites were fabricated and their dielectric properties were measured using the waveguide method at a frequency range of 8–12 GHz. At 10 GHz, the experimental results agreed well with the calculated results from the model for the SFT composites, while a positive hybrid effect on the dielectric constant was observed for the two hybrid composites.

“Mixing rules” for estimating the hydraulic permeability of fiber mixtures

AbstractWhile theoretical results for the hydraulic permeability of fibrous media are typically based on a single type of fiber in an ordered array, many synthetic or biological materials are composed of fibers which differ in size, charge, orientation, or other characteristics. It is desirable to be able to estimate the permeability of such a mixture from its composition and the properties of the individual fiber types. Toward that end, we compared four “mixing rules” proposed in the literature, each based on differing approximations of the hydrodynamic interactions between multiple fiber types. To provide data for charged fibers, the open‐circuit hydraulic permeabilities of periodic arrays of fibers with different surface charge densities and/or radii were computed using finite element methods. Based on these data for charged fibers, as well as published results for arrays of uncharged fibers of differing radii and/or orientation, we compared the four mixing rules for 64 cases. In some situations there were several‐fold differences among the predicted hydraulic permeabilities. Nonetheless, a volume‐weighted averaging of the resistivities of individual fiber types was found to be reasonably reliable, giving an overall root‐mean‐square error of 24%. This mixing rule was equally applicable to systems containing charged or neutral fibers. © 2007 American Institute of Chemical Engineers AIChE J, 2008

Modulation of pectoralis muscle function in budgerigarsMelopsitaccus undulatusand zebra finchesTaeniopygia guttatain response to changing flight speed

Flight power varies in a U-shaped relationship with flight speed, requiring the modulation of flight muscle power in order to meet these changing power demands. The power output of the pectoralis muscle can potentially be modulated by changing strain trajectory and the relative timing and intensity of muscle activity. Pectoralis muscle length change and activity patterns were recorded in budgerigars Melopsitaccus undulatus and zebra finches Taeniopygia guttata at a range of flight speeds using sonomicrometry and electromyography (EMG). The pectoralis muscles in these species contain a single muscle fibre type. Therefore, the power output is entirely determined by muscle activity and strain trajectory, rather than recruitment of motor units with different contractile properties as in many other vertebrate muscle systems. Relative EMG intensity, wingbeat frequency and muscle strain varied in an approximately U-shaped relationship with flight speed. The shape of the length trajectory varied with flight speed in budgerigars, with the proportion of the cycle spent shortening being lowest at intermediate flight speeds. In zebra finch pectoralis muscle the shape of the length trajectory did not vary significantly with flight speed. In both species the observed changes in muscle recruitment and length trajectory are consistent with meeting flight power requirements that vary in a U-shaped pattern with speed. Both species utilised intermittent flight, tending to spend relatively less time flapping at intermediate flight speeds. This supports the idea that intermittent flight is used as a simple power modulation strategy. However, the idea that intermittent flight serves to maintain a 'fixed gear' is over-simplistic and fails to recognise the plasticity in performance at the level of the muscle. Intermittent flight is only one component of a complex power modulation strategy.

Tensile, impact and dielectric properties of three dimensional orthogonal aramid/glass fiber hybrid composites

Aramid/glass hybrid composites with three different stacking sequences and their corresponding single fiber type composites have been fabricated and their tensile, impact and dielectric properties were investigated. The trend of tensile strength and modulus of the composites followed the rule of mixture (ROM) closely and a small but positive hybrid effect for tensile strength of the hybrid composites was observed. The hybrid composites in general had a higher impact resistance than the single fiber type composites and the hybrid composite in which fiber volume fractions for glass and aramid fiber were the most balanced showed the highest impact ductility. The aramid fiber composite showed a lower dielectric constant and a higher dielectric loss than the glass fiber composites. However, the dielectric constant of the hybrid composites decreased first and then increased as the volume fraction of aramid fiber increased, which did not follow the mixing rule for dielectric constants of compounds. The dielectric loss of the composites increased monotonically as the volume fraction of aramid fiber increased which agreed well with the mixing rule.

Progressive Failure of Marine GFRP Laminated Plates Under Static Water Pressure

This study examines the progressive failure of marine glass fiberreinforced plastic (GFRP) laminates subjected to out-of-plane water pressure. First, experimental data concerning laminates that consist of a single type of fiber are used to establish the finite element model by separating the section into fiber layers and matrix layers. After a suitable failure criterion has been specified and the stiffness modification factor of different materials obtained experimentally, a numerical model is used to simulate the failure behavior of marine GFRP laminates. This numerical model is then applied to analyze the failure of GFRP ship bottom structures under water pressure. The water pressure failure experiment is designed to verify the numerical results. The experimental system includes a watertight cabin, which comprises the wall of the fixture, the specimen, and a movable piston, filled with water. Then, the water pressure is increased by moving the piston to compress the water-sealed zone, until the specimen reaches ultimate failure. After the numerical model has been validated, the abilities of testing and analyzing the failure behavior of laminates under static water pressure are established. More information is presented about the capacity to resist out-of-plane water pressure, the proper use of the material, and improving the efficiency of the design.

Flexural Response of Hybrid Fiber-Reinforced Cementitious Composites

In fiber-reinforced concrete (FRC), fibers can be effective in arresting cracks at both macro and micro levels. Most of the FRC used today involves the use of a single fiber type, which implies that any fiber can provide reinforcement only at one level and within a limited range of strain or crack opening. For an optimal response, various types of fibers may be combined to produce hybrid fiber-reinforced concrete (HyFRC). The influence was quantified of various hybrid fiber combinations on fresh properties of concrete (that is, workability) and on hardened properties such as compressive strength. The objectives of the present study, however, were to investigate the flexural toughness properties of hybrid fiber-reinforced concrete and to identify synergistic effects between fibers, if present. The study found that some hybrid composites demonstrated some synergy between fibers.

Solid freeform fabrication of epoxidized soybean oil/epoxy composites with di‐, tri‐, and polyethylene amine curing agents

AbstractSoybean oil/epoxy‐based composites are prepared by solid freeform fabrication (SFF) methods. SFF methods built materials by the repetitive addition of thin layers. The mixture of epoxidized soybean oil and epoxy resin is modified with di‐, tri‐, or polyethylene amine gelling agent to solidify the materials until curing occurs. The high strength and stiffness composites are formed through fiber reinforcement. E‐glass, carbon, and mineral fibers are used in the formulations. The type of fiber affects the properties of the composites. It was found that a combination of two types of fibers could be used to achieve higher strength and stiffness parts than can be obtained from a single fiber type. In addition, the effects of curing temperature, curing time, and fiber concentration on mechanical properties of composites are studied and reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 356–363, 2004