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This study presents a comprehensive discrete element method (DEM) simulation approach for the stretching of a filter fiber with a separated polydisperse particle structure on top. For a realistic interaction between the fiber surface and the particles, the original surface of the polymer fiber was projected onto the surface of the fiber cylinder using surface imaging technologies (atomic force microscopy (AFM) and white-light interferometry). In addition, the adhesive forces between particle–fiber and particle–particle contacts were calibrated in the DEM domain using values from self-conducted AFM measurements. Fiber stretching was implemented by the linear motion of small periodic fiber elements. Discretization problems were resolved through studying the stretching of a fiber segment at the size of 8 mm. A critical fiber element length was discovered to be ≈100 μm for minimizing discretization dependencies during the cracking of the particle structure. The number and density of particle–particle contacts within the particle loading on the fiber were obtained at two different elongation rates. Effects such as densification of the particulate structure and increased detachment due to additional air flow were demonstrated. [ABSTRACT FROM AUTHOR]

The bonding performance and formation of the interphase region between fiber and matrix have significant effects on the strength and durability of composites. A new approach, involving combined experimental and numerical analyses, has been developed to avoid the shortcomings and scattering associated with local experimental methods. For this purpose, tensile tests are performed on specimens fabricated from a single glass fiber and epoxy resin. The elongations for specified lengths are measured using the digital image correlation (DIC) technic. The size of the fiber diameter and specimen section are also measured from SEM images. The obtained experimental displacements for micro tensile tests are used in an inverse elastic finite element solution to obtain the interphase elastic modulus. It is shown that, considering the interphase thickness of 1.0 μm that is more realistic, the interphase elastic modulus is in the range of 12 ∼ 19 GPa. However, the performed sensitivity analysis shown that considering interphase thickness ranging from zero to 2.0 μm the interphase elastic modulus varies between 9 and 46 GPa. It is shown that the proposed procedure can be used to obtain the overall mechanical properties of the matrix/fiber interphase in long fiber composites. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive discrete element method (DEM) simulation approach for the stretching of a filter fiber with a separated polydisperse particle structure on top. For a realistic interaction between the fiber surface and the particles, the original surface of the polymer fiber was projected onto the surface of the fiber cylinder using surface imaging technologies (atomic force microscopy (AFM) and white-light interferometry). In addition, the adhesive forces between particle–fiber and particle–particle contacts were calibrated in the DEM domain using values from self-conducted AFM measurements. Fiber stretching was implemented by the linear motion of small periodic fiber elements. Discretization problems were resolved through studying the stretching of a fiber segment at the size of 8 mm. A critical fiber element length was discovered to be ≈100 μm for minimizing discretization dependencies during the cracking of the particle structure. The number and density of particle–particle contacts within the particle loading on the fiber were obtained at two different elongation rates. Effects such as densification of the particulate structure and increased detachment due to additional air flow were demonstrated.

ABSTRACTThe modification method of grafting multi-walled carbon nanotubes (MWCNT, abbreviated as CNT in this paper) on the surface of flax fibers was investigated, i.e. CNT were grafted onto the surface of flax fibers by silane coupling agent under the action of ultrasonic waves to form covalent bonding. The tensile strength of CNT grafted flax fiber is 22% higher than that of untreated flax fiber monofilament. The tensile strength of FFRP composites after CNT grafting treatment increased by 14.2%; however, the tensile modulus of single fiber and composites did not show a significant increase, the interfacial shear strength of the fiber-resin is 38.3% higher than that of untreated filament. The improvement of the contact angle after grafting was investigated by observing the surface morphology, and the surface of flax filament was characterized by scanning electron microscopy and atomic force microscopy. Also the elemental changes of the flax single fiber surface before and after the treatment were analyzed using X-ray photoelectron spectroscopy. The results showed that the tensile strength of flax single fibers, its composites, and interfacial shear strength of fiber-matrix was improved after CNT grafting treatment but the increase of modulus was not obvious.

There are technical challenges in imaging studies that can three‐dimensionally (3D) analyze a single fiber (SF) to observe the functionality of the entire muscle after stroke. This study proposes a 3D assessment technique that only segments the SF of the right stroke‐induced soleus muscle of a gerbil using synchrotron radiation x‐ray microcomputed tomography (SR‐μCT), which is capable of muscle structure analysis. Curvature damage in the SF of the left soleus muscle (impaired) progressed at 7‐day intervals after the stroke in the control; particularly on the 7 days (1 week) and 14 days (2 weeks), as observed through visualization analysis. At 2 weeks, the SF volume was significantly reduced in the control impaired group (p =.033), and was significantly less than that in the non‐impaired group (p =.009). We expect that animal post‐stroke studies will improve the basic field of rehabilitation therapy by diagnosing the degree of SF curvature. Research Highlights: Muscle evaluation after ischemic stroke using synchrotron radiation x‐ray microcomputed tomography (SR‐μCT).Curvature is measured by segmenting a single fiber (SF) in the muscle.Structural changes in the SF of impaired gerbils at 7‐day intervals were assessed. [ABSTRACT FROM AUTHOR]

In this study, the traditional mini split Hopkinson tension bar (SHTB) was enhanced for the dynamic mechanical performance testing of single fiber/resin interface of composites. Single Aramid III fibers were modified using a polyamine modification treatment. Quasi-static and dynamic tensile tests of modified single Aramid III fibers were conducted using an electronic tensile testing machine and mini SHTB. The test results indicated that the surface modification employing the Catechol-Tetraethylenepentamine (Cat-TEPA) approach had a negligible effect on the tensile mechanical properties of single Aramid III fibers. The microdroplet method was introduced to measure the dynamic interfacial shear strength (IFSS) of Aramid III fiber/waterborne polyurethane resin using a mini SHTB. The dynamic shear test results revealed an increase in the dynamic shear strength of the modified Aramid III fiber/resin interface from 36.16 MPa to 41.51 MPa. Furthermore, the Scanning Electron Microscope (SEM) photography of the modified single Aramid III fiber after debonding exhibited regular grid structures on the debonding area, which can prevent debonding between the single fiber and the microdroplet, thereby enhancing interfacial shear performance. [ABSTRACT FROM AUTHOR]

Background: The complex network connections, information transmission and organization play key roles in brain cognition on sensory stimulation. Previous studies showed that several brain regions of somatosensory, motor, emotional, cognitive, etc. are linked to fabric‐evoked prickle. But the functional connectivity characteristics of the brain network involved in prickle perception is still unclear. Materials and Methods: In the present study, resting state fMRI (functional magnetic resonance imaging) with functional connectivity analysis was adopted to build the initial brain functional network, and task fMRI with psychophysiological interaction analysis was employed to investigate modulation features of prickling task to functional connections in the brain network. Results: The results showed that, in resting state, six groups or sub‐networks can be identified in the prickle network, and when the subjects performed the prickling task, functional connectivity strength between some seed regions (e.g., somatosensory regions and precuneus, emotional regions and the prefrontal cortex, etc.) in the network increased. Conclusion: Combining resting‐state fMRI with task fMRI is a feasible and promising method to study functional connectivity characteristics of the brain network involved in prickle perception. It is inferred that the "itch" ingredient of prickle sensation was transmitted from somatosensory cortices to precuneus, and emotional attribute (e.g., pain) from somatosensory cortices to the prefrontal cortex and at last to emotional regions. [ABSTRACT FROM AUTHOR]

A current subject of research is the application of magnetic effects for the detachment of accumulated particles of fibrous collectors in gas particle separation. Initial studies have already shown the magnetically induced detachment behavior of a compact particle structure after a single deflection from a single fiber. In this study, the detachment behavior of particle structures with different morphologies from a single fiber is investigated as a function of the particle loading stage on the fiber, the external magnetic flux density, the inflow velocity and the number of regenerations of the fiber for a certain parameter range. Diffusive and more compact particle structures with non-magnetic properties are deposited on the magnetizable single fiber. By applying an external magnetic field, the fiber is magnetized and experiences a torsional moment. The deposited particle structures on the fiber are detached by the acceleration forces. The detachment of the particle structures is observed using a high-speed camera and the image sequences are analyzed. By determining the projection area before and after the fiber deflection, a degree of regeneration is calculated. With magnetic-induced regeneration, high degrees of regeneration close to 100% can be achieved. Repetitive fiber deflections improve the detachment of the particle structures. The magnetic-induced regeneration is suitable for applications where flow reversal is not possible and can be performed either online or offline. Due to the gentle regeneration, fewer emissions are produced on the clean gas side than, for example, with jet pulse cleaning. It makes it easier to achieve emission limits and simplifies product recovery. [ABSTRACT FROM AUTHOR]

Environmentally friendly composites continue to be developed from kapok tree fiber (Ceiba pentandra) with an epoxy matrix. This study aims to characterize the tensile behavior of single fiber and its composite, the pull-out properties of kapok tree fiber, and morphology of the fiber. Kapok tree fibers were varied in the NaOH solution and the AESO polymer. Single fiber tensile test and pull out refer to the ASTM D3379-75 and ASTM E399 standards, respectively. The composite manufacturing method used in this research was the infusion vacuum resin method with reference to the ASTM D638 standard. The results of the tensile test (composite) showed that the kapok bark fiber with the characteristics of NaOH + Coating had a greater tensile strength (197,88 Mpa), than that without treatment and NaOH treatment. Of all the characteristics of the kapok bark fiber, the highest value of the tensile strength was the fiber treated with NaOH + Coating (KNC). The results of fiber morphology showed proved that the NaOH treatment increased the surface hardness by eliminating the bonds of surface crystallinity, topography, water absorption, unit cell structure and fiber orientation. These results indicate that kapok tree fiber treated with 7% NaOH + coating with AESO polymer has high potential as a structural material to replace wood or textile materials.

In this study, the traditional mini split Hopkinson tension bar (SHTB) was enhanced for the dynamic mechanical performance testing of single fiber/resin interface of composites. Single Aramid III fibers were modified using a polyamine modification treatment. Quasi-static and dynamic tensile tests of modified single Aramid III fibers were conducted using an electronic tensile testing machine and mini SHTB. The test results indicated that the surface modification employing the Catechol-Tetraethylenepentamine (Cat-TEPA) approach had a negligible effect on the tensile mechanical properties of single Aramid III fibers. The microdroplet method was introduced to measure the dynamic interfacial shear strength (IFSS) of Aramid III fiber/waterborne polyurethane resin using a mini SHTB. The dynamic shear test results revealed an increase in the dynamic shear strength of the modified Aramid III fiber/resin interface from 36.16 MPa to 41.51 MPa. Furthermore, the Scanning Electron Microscope (SEM) photography of the modified single Aramid III fiber after debonding exhibited regular grid structures on the debonding area, which can prevent debonding between the single fiber and the microdroplet, thereby enhancing interfacial shear performance.

Carbon fiber reinforced plastics are increasingly used in all areas of industry. With the increasing number of components and semi-finished products, more and more new carbon fibers will be produced. This also generates a greater number of end-of-life components. These end-of-life components can currently only be fed back, to a limited extent, for reuse, thus leading to a non-optimal, closed-material cycle of the carbon fiber. This article provides an overview of the recycling of carbon components, their further processing and their reuse in reinforcement elements made of carbon fibers. In addition, first results from recycled single fibers and yarn tensile tests from recycled carbon fibers (rCF) are presented. By demonstrating the reuse of carbon fibers in the construction sector, there is the potential to effectively close the carbon cycle. The utilization of carbon reinforcements also enables the reduction of concrete consumption, as the minimum concrete cover required to protect the reinforcement from corrosion is no longer needed. [ABSTRACT FROM AUTHOR]

The potential utilization of magnetic effects in gas particle separation is a current subject of research. This paper demonstrates for the first time that a single magnetizable filter fiber can be deflected by a magnetically induced excitation for a selected combination of parameters, resulting in the removal of deposited particle structures with high detachment levels. A correlation between the magnetic flux density and achieved acceleration to overcome the adhesive forces/strength of the particle structure was determined. The degree of detachment after each regeneration was calculated by comparing the projection area before and after detachment using high-speed images. At a magnetic flux density of B = 38.5 mT, accelerations of maximum a = 105 m·s−2 are achieved, depending on the axial position along the single fiber. The degrees of regeneration achieved at these parameters depend on the amount of fiber loading and on the fiber orientation in the gravitational field. The horizontal orientation of the fiber leads to an increased reattachment of precedingly detached particle structures after deflection compared to a vertical orientation. High particle loading on the fiber results in enhanced detachment by inertia. Under the most favorable process conditions investigated, detachment levels of >90% are achieved. [ABSTRACT FROM AUTHOR]

A current subject of research is the application of magnetic effects for the detachment of accumulated particles of fibrous collectors in gas particle separation. Initial studies have already shown the magnetically induced detachment behavior of a compact particle structure after a single deflection from a single fiber. In this study, the detachment behavior of particle structures with different morphologies from a single fiber is investigated as a function of the particle loading stage on the fiber, the external magnetic flux density, the inflow velocity and the number of regenerations of the fiber for a certain parameter range. Diffusive and more compact particle structures with non-magnetic properties are deposited on the magnetizable single fiber. By applying an external magnetic field, the fiber is magnetized and experiences a torsional moment. The deposited particle structures on the fiber are detached by the acceleration forces. The detachment of the particle structures is observed using a high-speed camera and the image sequences are analyzed. By determining the projection area before and after the fiber deflection, a degree of regeneration is calculated. With magnetic-induced regeneration, high degrees of regeneration close to 100% can be achieved. Repetitive fiber deflections improve the detachment of the particle structures. The magnetic-induced regeneration is suitable for applications where flow reversal is not possible and can be performed either online or offline. Due to the gentle regeneration, fewer emissions are produced on the clean gas side than, for example, with jet pulse cleaning. It makes it easier to achieve emission limits and simplifies product recovery.

Carbon fiber reinforced plastics are increasingly used in all areas of industry. With the increasing number of components and semi-finished products, more and more new carbon fibers will be produced. This also generates a greater number of end-of-life components. These end-of-life components can currently only be fed back, to a limited extent, for reuse, thus leading to a non-optimal, closed-material cycle of the carbon fiber. This article provides an overview of the recycling of carbon components, their further processing and their reuse in reinforcement elements made of carbon fibers. In addition, first results from recycled single fibers and yarn tensile tests from recycled carbon fibers (rCF) are presented. By demonstrating the reuse of carbon fibers in the construction sector, there is the potential to effectively close the carbon cycle. The utilization of carbon reinforcements also enables the reduction of concrete consumption, as the minimum concrete cover required to protect the reinforcement from corrosion is no longer needed.

Besides, the transmittivity/reflectivity of grating spectrum is reached to approximation of 97.5 % at central Bragg wavelength value of 1.55 m. In the other side, the reflection level is reached to -59 dB, average group delay ripple is reached to 0.63 and output pulse intensity approximation is reached to 94.8 % at approximation zero delay time. In OptiGrating simulation, the grating shape is the sine index modulation profile within one grating period is given by: HT ht Graph (8) Constant grating period with no chirp is estimated by the following mathematical formula: HT ht Graph (9) In order to estimate the average group delay ripple in this study, which is given by the following formula based on Ref [[12]]: HT ht Graph (10) where I A SB apod sb i and I A SB unapod sb i are the apodized and unapodized peak to peak group delay ripple amplitude respectively, and I i is the sharpness parameter. [Extracted from the article]

The potential utilization of magnetic effects in gas particle separation is a current subject of research. This paper demonstrates for the first time that a single magnetizable filter fiber can be deflected by a magnetically induced excitation for a selected combination of parameters, resulting in the removal of deposited particle structures with high detachment levels. A correlation between the magnetic flux density and achieved acceleration to overcome the adhesive forces/strength of the particle structure was determined. The degree of detachment after each regeneration was calculated by comparing the projection area before and after detachment using high-speed images. At a magnetic flux density of B = 38.5 mT, accelerations of maximum a = 105 m·s−2 are achieved, depending on the axial position along the single fiber. The degrees of regeneration achieved at these parameters depend on the amount of fiber loading and on the fiber orientation in the gravitational field. The horizontal orientation of the fiber leads to an increased reattachment of precedingly detached particle structures after deflection compared to a vertical orientation. High particle loading on the fiber results in enhanced detachment by inertia. Under the most favorable process conditions investigated, detachment levels of >90% are achieved.

Fiber traces are one of (micro)traces that can be found at a crime scene. They are easily transferable and, like other forms of evidence, can provide a link between a suspect and a victim. The main purpose of this review is to present methods developed to examine textile dyes extracted for forensic purposes using different capillary electromigration methods (CEMs). Scientific papers, mainly from the 20th century, provide reliable methods for the separation of water-soluble dyes. However, dyes insoluble in aqueous solutions have been and still are a challenge. Another problem is the sensitivity of the developed methods, which is, in most cases, insufficient for forensic examination of dyes extracted from a single fiber preserved at the crime scene. Although the methodologies already developed and presented in this review have the potential to be applied in a comparative analysis of textile dye traces, there seems to be a lot of work to be conducted. Some ideas on how to resolve these problems are presented and discussed in the article. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT) fibers have been extensively investigated along the longitudinal direction and are well-known for their high axial tensile strength and modulus. However, after being manufactured into textiles or composites, these fibers are usually subjected to transverse loading during their normal service life. Deformation and failure of CNT fibers induced by external loads in the transverse direction lack examination. This study integrated single-fiber quasi-static and dynamic transverse loading techniques with scanning electron microscopy (SEM) and high-speed imaging, respectively. An extreme condition was considered as the indenter was a sharp razor blade. Failure behavior of single CNT fibers transversely loaded by the blade at different velocities was visualized, and axial mechanical response of these fibers was measured. The fracture surface of CNT fibers was examined by SEM. Additional experimental investigations were performed on commercialized two organic (aramid and ultrahigh molecular weight polyethylene) and two inorganic (ceramic and glass) fibers. It is revealed that CNT fibers experienced initial contact with the blade, followed by partial incision, and ultimately tensile failure. Furthermore, the energy dissipation and dispersion capabilities of CNT fibers per unit mass were demonstrated to surpass that of commercialized high-performance fibers during extreme transverse loading. As the loading rate increased, the energy dissipation of CNT fibers was further improved by 2.1 times. Such high performance of CNT fibers in resisting extreme transverse loading was presumably attributed to the high hardness, strength, and stiffness of CNTs in the transverse direction and weak intermolecular interactions in the axial direction. This study expands material characterization of CNT fibers in the transverse direction and reveals the fundamental failure mechanism of CNT fibers in the harsh environment, which is deemed useful to develop the fiber-scale model for textiles and composites.

Aim: The short-term and long-term efficacy of different thermal percutaneous ablation techniques remains a topical issue. Our group implemented percutaneous laser ablation (LA), a moving-shot technique to increase efficiency and reduce costs and variability of LA by applying multiple lower-intensity energy illuminations (MLIEI) covering the nodular volume (V) through changes in position of a single laser fiber within the thyroid nodule. The aim of the present study was to evaluate the efficacy of the single-fiber LA-MLIEI during a 5-year follow-up and to identify possible predictors of the final outcome. Methods: Prospective study : Thirty outpatients (23 women and seven men) with benign symptomatic thyroid nodules were assigned to single-fiber LA-MLIEI, between 2012 and 2015. A single LA session was performed under real-time ultrasound (US) guidance using a 1,064-nm continuous-wave laser at 3 W. A 400-µm optical fiber was inserted through a 21-gauge needle, and 3–10 illuminations were performed per nodule, administering between 400 and 850 J/illumination. The total administered energy was calculated on the initial V of the nodule and the estimated ablation area. US evaluation was performed after LA-MLIEI at 1 week and 1, 3, 6, and 12 months and after that annually up to 5 years. Clinical symptoms, laboratory thyroid function during follow-up, and acute and chronic complications of treatment were registered. Results: On follow-up, 67% (n: 20) were responders to single-fiber LA-MLIEI, while 33% (n: 10) were non-responders. The responder group initiated V reduction (ΔV) at 1 month, with remission of symptoms, and presented a 50% ΔV at 3 months of treatment; the maximum response was achieved at 24 months and remained stable until the end of the study. The non-responder group presented a ΔV of less than 50% at 12 months; though a tendency to >50% ΔV was observed at 24–36 months, there was subsequent regrowth, and 40% of this group required surgery. ΔV was positively correlated with the total administered energy/V (J/V) and inversely with nodule V. No severe adverse effects were observed. Thyroid function remained normal in all patients. Remission of symptoms occurred rapidly after 1 month. Conclusions: LA with multiple fractional discharges employing a single fiber in a unique session is a safe and inexpensive technique that allows rapid reduction of thyroid nodules, with a stable response up to 5 years, similarly to what has been reported with the conventional LA. Total nodule volume appears as a predictive factor of the reduction. [ABSTRACT FROM AUTHOR]

AimThe short-term and long-term efficacy of different thermal percutaneous ablation techniques remains a topical issue. Our group implemented percutaneous laser ablation (LA), a moving-shot technique to increase efficiency and reduce costs and variability of LA by applying multiple lower-intensity energy illuminations (MLIEI) covering the nodular volume (V) through changes in position of a single laser fiber within the thyroid nodule. The aim of the present study was to evaluate the efficacy of the single-fiber LA-MLIEI during a 5-year follow-up and to identify possible predictors of the final outcome.MethodsProspective study: Thirty outpatients (23 women and seven men) with benign symptomatic thyroid nodules were assigned to single-fiber LA-MLIEI, between 2012 and 2015. A single LA session was performed under real-time ultrasound (US) guidance using a 1,064-nm continuous-wave laser at 3 W. A 400-µm optical fiber was inserted through a 21-gauge needle, and 3–10 illuminations were performed per nodule, administering between 400 and 850 J/illumination. The total administered energy was calculated on the initial V of the nodule and the estimated ablation area. US evaluation was performed after LA-MLIEI at 1 week and 1, 3, 6, and 12 months and after that annually up to 5 years. Clinical symptoms, laboratory thyroid function during follow-up, and acute and chronic complications of treatment were registered.ResultsOn follow-up, 67% (n: 20) were responders to single-fiber LA-MLIEI, while 33% (n: 10) were non-responders. The responder group initiated V reduction (ΔV) at 1 month, with remission of symptoms, and presented a 50% ΔV at 3 months of treatment; the maximum response was achieved at 24 months and remained stable until the end of the study. The non-responder group presented a ΔV of less than 50% at 12 months; though a tendency to >50% ΔV was observed at 24–36 months, there was subsequent regrowth, and 40% of this group required surgery. ΔV was positively correlated with the total administered energy/V (J/V) and inversely with nodule V. No severe adverse effects were observed. Thyroid function remained normal in all patients. Remission of symptoms occurred rapidly after 1 month.ConclusionsLA with multiple fractional discharges employing a single fiber in a unique session is a safe and inexpensive technique that allows rapid reduction of thyroid nodules, with a stable response up to 5 years, similarly to what has been reported with the conventional LA. Total nodule volume appears as a predictive factor of the reduction.

There are limited and equivocal data regarding potential fiber type-specific differences in the human skeletal muscle response to sprint interval training (SIT), including how this compares with moderate-intensity continuous training (MICT). We examined mixed-muscle and fiber type-specific responses to a single session (study 1) and to 12 wk (study 2) of MICT and SIT using Western blot analysis. MICT consisted of 45 min of cycling at ∼70% of maximal heart rate, and SIT involved 3 × 20-s "all-out" sprints interspersed with 2 min of recovery. Changes in signaling proteins involved in mitochondrial biogenesis in mixed-muscle and pooled fiber samples were similar after acute MICT and SIT. This included increases in the ratios of phosphorylated to total acetyl-CoA carboxylase and p38 mitogen-activated protein kinase protein content (main effects, P < 0.05). Following training, mitochondrial content markers including the protein content of cytochrome c oxidase subunit IV and NADH:ubiquinone oxidoreductase subunit A9 were increased similarly in mixed-muscle and type IIa fibers (main effects, P < 0.05). In contrast, only MICT increased these markers of mitochondrial content in type I fibers (interactions, P < 0.05). MICT and SIT also similarly increased the content of mitochondrial fusion proteins optic atrophy 1 (OPA1) and mitofusin 2 in mixed-muscle, and OPA1 in pooled fiber samples (main effects, P < 0.02). In summary, acute MICT and SIT elicited similar fiber type-specific responses of signaling proteins involved in mitochondrial biogenesis, whereas 12 wk of training revealed differential responses of mitochondrial content markers in type I but not type IIa fibers.NEW & NOTEWORTHY We examined mixed-muscle and fiber type-specific responses to a single session and to 12 wk of moderate-intensity continuous training (MICT) and sprint interval training (SIT) in humans. Both interventions elicited generally similar responses, although the training-induced increases in type I fiber-specific markers of mitochondrial content were greater in MICT than in SIT. These findings advance our understanding of the potential role of fiber type-specific changes in determining the human skeletal muscle response to intermittent and continuous exercise. [ABSTRACT FROM AUTHOR]

Fiber traces are one of (micro)traces that can be found at a crime scene. They are easily transferable and, like other forms of evidence, can provide a link between a suspect and a victim. The main purpose of this review is to present methods developed to examine textile dyes extracted for forensic purposes using different capillary electromigration methods (CEMs). Scientific papers, mainly from the 20th century, provide reliable methods for the separation of water-soluble dyes. However, dyes insoluble in aqueous solutions have been and still are a challenge. Another problem is the sensitivity of the developed methods, which is, in most cases, insufficient for forensic examination of dyes extracted from a single fiber preserved at the crime scene. Although the methodologies already developed and presented in this review have the potential to be applied in a comparative analysis of textile dye traces, there seems to be a lot of work to be conducted. Some ideas on how to resolve these problems are presented and discussed in the article.

Introduction: The passive mechanical behavior of skeletal muscle represents both important and generally underappreciated biomechanical properties with little attention paid to their trainability. These experiments were designed to gain insight into the trainability of muscle passive mechanical properties in both single fibers and fiber bundles.Methods: Rats were trained in two groups: 4 weeks of either uphill (UH) or downhill (DH) treadmill running; with a third group as sedentary control. After sacrifice, the soleus (SOL), extensor digitorum longus (EDL), and vastus intermedius (VI) were harvested. One hundred seventy-nine bundles and 185 fibers were tested and analyzed using a cumulative stretch-relaxation protocol to determine the passive stress and elastic modulus. Titin isoform expression was analyzed using sodium dodecyl sulfate vertical agarose gel electrophoresis (SDS-VAGE).Results: Single fibers: passive modulus and stress were greater for the EDL at sarcomere lengths (SLs) ≥ 3.7 μm (modulus) and 4.0 μm (stress) with DH training compared to UH training and lesser for the SOL (SLs ≥ 3.3 μm) with DH training compared with control; there was no effect of UH training. Vastus intermedius was not affected by either training protocol. Fiber bundles: passive modulus and stress were greater for the EDL at SLs ≥ 2.5 μm (modulus) and 3.3 μm (stress) in the DH training group as compared with control, while no affects were observed in either the SOL or VI for either training group. No effects on titin isoform size were detected with training.Conclusion: This study demonstrated that a trainability of passive muscle properties at both the single fiber and fiber bundle levels was not accompanied by any detectable changes to titin isoform size.

Introduction: The passive mechanical behavior of skeletal muscle represents both important and generally underappreciated biomechanical properties with little attention paid to their trainability. These experiments were designed to gain insight into the trainability of muscle passive mechanical properties in both single fibers and fiber bundles. Methods: Rats were trained in two groups: 4 weeks of either uphill (UH) or downhill (DH) treadmill running; with a third group as sedentary control. After sacrifice, the soleus (SOL), extensor digitorum longus (EDL), and vastus intermedius (VI) were harvested. One hundred seventy-nine bundles and 185 fibers were tested and analyzed using a cumulative stretch-relaxation protocol to determine the passive stress and elastic modulus. Titin isoform expression was analyzed using sodium dodecyl sulfate vertical agarose gel electrophoresis (SDS-VAGE). Results: Single fibers: passive modulus and stress were greater for the EDL at sarcomere lengths (SLs) ≥ 3.7 μm (modulus) and 4.0 μm (stress) with DH training compared to UH training and lesser for the SOL (SLs ≥ 3.3 μm) with DH training compared with control; there was no effect of UH training. Vastus intermedius was not affected by either training protocol. Fiber bundles: passive modulus and stress were greater for the EDL at SLs ≥ 2.5 μm (modulus) and 3.3 μm (stress) in the DH training group as compared with control, while no affects were observed in either the SOL or VI for either training group. No effects on titin isoform size were detected with training. Conclusion: This study demonstrated that a trainability of passive muscle properties at both the single fiber and fiber bundle levels was not accompanied by any detectable changes to titin isoform size. [ABSTRACT FROM AUTHOR]

Anion conductive nanofiber mats from FAA‐3 ionomers are obtained by electrospinning. Depending on the solvent used in the precursor solution, nanofibers with either nonhollow cylindrical or flat ribbon‐like cross‐sections are prepared. The anion conductivity and water uptake of the ionomeric nanofiber mats are measured as a function of the relative humidity in the 10–90% range and compared to that of a solid membrane cast from the same ionomer. In addition, the anion conductivity of an isolated single fiber of the ionomer is measured for the first time. The anion conductivity of the electrospun single fiber is found to be higher than that of the mats, which is, in turn, one order of magnitude higher than that of the solid ionomer membrane. The higher conductivity of the mats relative to the solid membrane (in both in‐plane and through‐plane directions) is found to be related to the variation in water uptake, which stems from the morphological distinctions. These results increase the understanding of the electrospinning process of ionomers, toward the development and design of new anion conductive ionomer fibers, useful for high performance electrochemical devices. [ABSTRACT FROM AUTHOR]

Aerobic exercise capacity is critical to bodily health. As a model to investigate the mechanisms that determine health and disease, we employed low (LCR) and high (HCR) capacity running rat models selectively bred to concentrate the genes responsible for divergent aerobic running capacity. To investigate the skeletal muscle contribution to this innate difference in running capacity we employed an approach combining examination of the myofilament protein composition and contractile properties of the fast fiber extensor digitorum longus (EDL) and slow fiber soleus (SOL) muscles from LCR and HCR rats. Intact muscle force experiments demonstrate that SOL, but not EDL, muscles from LCR rats exhibit a three times greater decrease in fatigued force. To investigate the mechanism of this increased fatigability in the LCR SOL muscle, we determined the myofilament protein composition and functional properties. Force-Ca2+ measurements demonstrate decreased Ca2+ sensitivity of single skinned SOL muscle fibers from LCR compared with that of HCR rats. Segregating SOL fibers into fast and slow types demonstrates that the decreased Ca2+ sensitivity in LCR SOL results from a specific decrease in slow-type SOL fiber Ca2+ sensitivity such that it was similar to that of fast-type fibers. These results identify that the altered myofilament contractile properties of LCR SOL slow-type fibers result in a fast muscle type Ca2+ sensitivity and the LCR muscle phenotype. Overall our findings demonstrate alterations of the myofilament proteins could contribute to fatigability of the SOL muscle and the decreased innate aerobic running performance of LCR compared with HCR rats. [ABSTRACT FROM AUTHOR]

High-performance fiber-reinforced composites (FRCs) are widely used in bulletproof structures, in which the mechanical properties of the single fibers play a crucial role in ballistic resistance. In this paper, the quasi-static and dynamic mechanical properties of three commonly used fibers, single aramid III, polyimide (PI), and poly-p-phenylenebenzobisoxazole (PBO) fibers are measured by a small-scale tensile testing machine and mini-split Hopkinson tension bar (mini-SHTB), respectively. The results show that the PBO fiber is superior to the other two fibers in terms of strength and elongation. Both the PBO and aramid III fibers exhibit an obvious strain-rate strengthening effect, while the tensile strength of the PI fiber increases initially, then decreases with the increase in strain rate. In addition, the PBO and aramid III fibers show ductile-to-brittle transition with increasing strain rate, and the PI fiber possesses plasticity in the employed strain rate range. Under a high strain rate, a noticeable radial splitting and fibrillation is observed for the PBO fiber, which can explain the strain-rate strengthening effect. Moreover, the large dispersion of the strength at the same strain rate is observed for all the single fibers, and it increases with increasing strain rate, which can be ascribed to the defects in the fibers. Considering the effect of strain rate, only the PBO fiber follows the Weibull distribution, suggesting that the hypothesis of Weibull distribution for single fibers needs to be revisited.

Erucamide is known to play a critical role in modifying polymer fiber surface chemistry and morphology. However, its effects on fiber crystallinity and mechanical properties remain to be understood. Here, synchrotron nanofocused X-ray Diffraction (nXRD) revealed a bimodal orientation of the constituent polymer chains aligned along the fiber axis and cross-section, respectively. Erucamide promoted crystallinity in the fiber, leading to larger and more numerous lamellae crystallites. The nXRD nanostructual characterization is complemented by single-fiber uniaxial tensile tests, which showed that erucamide significantly affected fiber mechanical properties, decreasing fiber tensile strength and stiffness but enhancing fiber toughness, fracture strain, and ductility. To correlate these single-fiber nXRD and mechanical test results, we propose that erucamide mediated slip at the interfaces between crystallites and amorphous domains during stress-induced single-fiber crystallization, also decreasing the stress arising from the shear displacement of microfibrils and deformation of the macromolecular network. Linking the single-fiber crystal structure with the single-fiber mechanical properties, these findings provide the direct evidence on a single-fiber level for the role of erucamide in enhancing fiber "softness".

To reveal the flow characteristics in the packed bed of a fiber filter, the collision behaviors of water droplets with a single stainless steel (SS) fiber in oil were investigated. First, the forces acting on the water droplets during collisional processes were analyzed; then, a systematic test based on the visualization method was conducted to elucidate the effects of the emulsion flow rate, the value of N = rd/rf (ratio of the radii of the water droplets and the fiber) and oil viscosity on the motions of the water droplets colliding with the fibers. It was revealed that increasing the emulsion flow rate and N can clearly improve the collision velocity and the efficiency of the water droplet collision with a single fiber. However, the influence of the oil viscosity on the velocity of the water droplets approaching the SS fibers can be ignored. All of the findings will facilitate the design of efficient fibrous bed coalescers for emulsion and aerosol purification. [ABSTRACT FROM AUTHOR]

Sugar palm (Arenga pinnata) is a type of natural fiber that belongs to the Palmae family. It is versatile, readily available, and virtually the entire tree can be formed into many different products. This paper discusses the effect of vacuum resin impregnation on a single sugar palm fiber (SPF) using various thermosetting resins such as epoxy, vinyl ester (VE), and polyester (PE). The fibers were vacuum impregnated at a constant pressure of 600 mmHg for 5 min. The excessive resins were wiped off, and the impregnated fibers were cured in an oven for approximately 30 min at a temperature of 140 °C. Following this, the tensile properties of the single SPF impregnated with epoxy, VE, and PE were determined. The results indicated that impregnation of SPF with epoxy resin increased the tensile strength and modulus of SPF 50% and 59%, respectively. Scanning electron microscope images also illustrated that the epoxy resin offered better impregnation on the SPF compared to the other thermosetting resins. A suitable application for the impregnated SPF is as a roofing material. [ABSTRACT FROM AUTHOR]

As a satisfactory green material for a lithium ion battery separator, cellulose possesses better wettability and superior thermal and chemical stability compared to commercial polyolefin separators. The macroscopic mechanical properties of the separator are determined by structural parameters on different dimensional scales. In this paper, a two‐scale modelling method is proposed for a cellulose separator. At micro‐scale, a single fiber structural model was established with a cross‐sectional profile extracted through image processing, combined with the fiber helix angle. At meso‐scale, a representative volumetric element model and a two‐dimensional random fibrous model for the fibrous network of the cellulose separator were developed. The elastic modulus in the machining direction (MD) and transverse direction (TD) of the two models were calculated by finite element simulation and compared with experimental data. The results show that the elastic modulus of the models is slightly larger than that from experiments. Compared to experiments, the relative errors in the MD and TD of the representative volumetric element model are 2.80% and 6.78%, respectively. The relative errors in the MD and TD of the two‐dimensional random fibrous model are 6.70% and 8.47%, respectively. Consequently, multi‐scale modelling is proven to have considerable value in investigating the properties of fibrous materials. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

We developed a microscopic experimental method that transversely loads and images single high-performance fibers. The experimental set-up was inside the chamber of a scanning electron microscope (SEM). Force and displacement histories were recorded by the loading device. The SEM enabled in-situ observation of the fiber's initial contact with the transverse indenter and subsequent deformation, crack initiation and propagation until the final failure. Within the loading device, fiber gauge length, indenter tip radius and loading direction can be varied as desired. To demonstrate the new experimental capability, initial results for a razor blade transversely cutting a Dyneema® SK76 fiber are presented in this paper. To avoid the effect from the conductive coating on the mechanical behavior of the fiber, a low vacuum detector was adopted to capture the deformation and failure of an uncoated fiber. These experiments revealed the damage and failure processes of single fibers with high-resolution micrographs. [ABSTRACT FROM AUTHOR]

Single high-performance fibers (Kevlar® K129, Twaron® 2040, Technora® T200, Dyneema® SK76, Zylon® AS, Vectran® HT, and S-glass) are subject to lateral cutting action by an industrial blade. Due to the inherent variability of such testing, 40–60 replicate experiments were performed for each fiber type, at each of three different loading orientations, and the data were fit with a generalized extreme value distribution to summarize likelihood of failure under each condition. The results show that when organic fibers are cut at an angle that introduces shear loads, cut resistance drops by 60–90% compared to normal-incidence cut loading. This trend is driven by the highly oriented and fibrillar nature of organic fibers, in contrast to the isotropic S-glass fibers which show comparatively little change in cut resistance with blade orientation. Overall, the Vectran fibers provide the best resistance to normal loading, while the S-glass fibers are most resistant to non-normal loading. Micrographs show that, for organic fibers, shear loads lead to more localized failure compared to normally loaded fibers. [ABSTRACT FROM AUTHOR]

Abstract Cellulose separators present promising properties applied in lithium-ion batteries but are confronted with strength issue in electrolyte. In this paper, mechanical and electrochemical properties of lithium-ion battery cellulose separator under electrolyte-immersed condition are studied. The tensile properties of the cellulose separators concerning electrolyte immersion time are investigated at multi-scales, which are fiber components, single fiber and cellulose separator. Electrochemical properties of cellulose separator are also studied. Experiments upon polypropylene/PP separator are also conducted for comparison. The results reveal that strength weakening and swelling both occur in fiber components, single fiber and cellulose separator. Softening of fiber components directly results in softening of the separator. Reduction of Young's modulus and tensile strength mainly happens within 30 min of immersion, while growing of elongation rate sustains as time proceeds. Swelling is verified to attribute to improvement of the electrochemical properties of cellulose separators, in which case, smaller interfacial impedance and larger electrochemical stable window were found. Compared to PP separator, the strength weakening of cellulose separator are relatively serious, which suggesting that balance should be explored between mechanical properties and electrochemical performance for cellulose separator. Highlights • Strength weakening and wellings of cellulose separator were unveiled at multi-scale. • Strength weakening and swelling is caused by electrolyte immersion. • Cellulose separator possesses inferior "wet" tensile properties. • Cellulose separator presents better interfacial properties. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a numerical study on the deposition behaviour of micro-particles on a solid surface has been carried out using the CFD-DEM coupled with in-house subroutines. We introduce a particle interaction model to predict the dynamic deposition behaviour. The model predicts the formation of the dendrites and the dynamic progression of the deposition very well. For the sub-micro particles which are dominated by the diffusion and interception mechanism, it is found that the particles are captured by the fibers and deposited on the surface of the fiber uniformly at the initial stage. With increasing deposited particles, the small agglomerates grow up to branched dendrites. Some of the particles are distributed on the surface of the fiber and the others are distributed on the particle dendrites. The effects of inlet flow velocity, particle diameter as well as fiber diameter on the deposition morphology and the collection efficiency are investigated comprehensively. The results indicated that a high collection efficiency could be achieved at relative smaller fluid velocity and bigger particle diameter. Meanwhile, the normalized pressure drop and the velocity gradient on both sides of the fiber increase with SVF. Such an increase in the pressure drop and velocity gradient contribute to a larger collection efficiency. Highlights • The particle deposition process on a fiber can be divided into two stages. • The collection efficiency gradually decreases as inlet fluid velocity increases from 0.1 to 0.8 m/s. • The collection efficiency increases as particle diameter increases from 0.5 to 1.0 µm. • The collection efficiency of the fiber increases as SVF increases. [ABSTRACT FROM AUTHOR]

For the design of a gas-cleaning filter, the morphology of particle deposits on filter fibers is of significant interest. In this study, particle structures were generated with polydisperse particulate material and mainly deposited by diffusion or by interception and inertia. The structures were characterized in situ with structures generated by monodisperse material known from literature. A quantitative comparison showed that the particle structures of polydisperse material are comparable to those of monodisperse material. It was demonstrated that only an in situ investigation provided artifact-free results for very dendritic particle structures of Carbon Black. At a Péclet number of Pe = 1.67⋅104, the dendrites are arranged uniformly around the fiber at an angle of 90° and folded down in the direction of the gravity field after the inflow was turned off. The particle structures of Carbon Black at higher Péclet numbers (2.6·105-1·106) are less dendritic and showed no visual change when the flow was switched off. However, they were not stable enough to be removed and further examined by laser scanning microscopy in addition to in situ observation. Only the particle structures made of glass spheres are stable enough and could be removed for further investigation. • The generated particle structures of polydisperse material are comparable to those of monodisperse material. • For soot at a Péclet-number of Pe = 1.67·104 , dendrites accumulate around the fiber. • The particle structures at Pe = 1.67·104 are very unstable and collapse as soon as the inflow is switched off. • Only in situ investigations provided artifact-free results for diffusive particle structures. [ABSTRACT FROM AUTHOR]

The study systematically explored the effect of alkali concentration and soaking time on the microstructure and tensile properties of single-cellulosic Buluh Semantan. Scanning electron microscopy and tensile tests were conducted to determine the effects of different alkali treatments on the properties of the single-cellulosic bamboo fibers. In particular, the effects of NaOH concentration and soaking time on the tensile properties of the single-cellulosic bamboo fiber were investigated. The single-cellulosic bamboo fiber was immersed in 2, 4, 6, and 8 wt.% aqueous NaOH solutions for soaking times of 1, 3, 6, 12, 18, and 24 h. The tensile properties of the fiber increased after each alkali treatment. The alkali concentration and soaking time significantly affected the fiber properties. The ultimate tensile strength of the single-cellulosic Buluh Semantan treated with 2 wt.% NaOH for 12 h decreased to 214 MPa relative to the fibers that experienced water retting. The highest tensile strength herein was 356.8 MPa for the single-cellulosic fiber that was soaked for 12 h in 4 wt.% NaOH. Comparatively, the tensile strength of the single-cellulosic bamboo fiber that was soaked for 12 h in 8 wt.% NaOH was 234.8 MPa. The tensile modulus of the single-cellulosic fiber was 12.06 GPa after soaking in 8 wt.% NaOH for 18 h, indicating that a strong alkali treatment negatively affected the stiffness and suitability for use of the fibers in applications. The topography of the fiber surface became much rougher after the alkali treatments due to the removal of hemicellulose and other surface impurities. The alkali treatments substantially changed the morphology of the fiber surface, suggesting an increase in wettability.