Flexibility Of Fiber Research Articles

Design of Poly(lactic) acid/gelatin core-shell bicomponent systems as a potential wound dressing material

The electrospun core-shell nanofiber has great many advantages such as different types of solvents that can be used for changing flexibility, mechanical properties, or surface chemistry of fiber. Hydrophobic Poly(lactic) acid (PLA) and hydrophilic gelatin (Gel) were electrospun by various preparation conditions to design perfect bicomponent PLA:Gel nanofiber in a core-shell structure. Solvent types, the concentration of polymeric components, flow rate, and voltage of the electrospinning process were changed to optimization of nanofiber. According to the SEM images, the best nanofiber structure without beads was obtained at 0.4 ml/h flow rate of PLA solution and 1.2 ml/h flow rate of Gel solution at 45:55 (w:w %) weight ratio of PLA:Gel in trifluoroethanol solvent with a 10 kV voltage at 10 cm distance to the collector. From the TEM images, the existence of the core-shell structure had been proved which all prepared nanofibers with 2,2,2-Trifluoroethanol solvent. Furthermore, contact angle measurements showed a change in wettability when the Gel amount was increased. Therefore, the mildest synthesis conditions were determined for bicomponent PLA:Gel core-shell nanofibers as a potential wound dressing and dual drug carrier materials.

H-Principle for Stratified Spaces

Abstract We extend Gromov and Eliashberg–Mishachev’s $h-$principle on manifolds to stratified spaces. This is done in both the sheaf-theoretic framework of Gromov and the smooth jets framework of Eliashberg–Mishachev. The generalization involves developing 1. the notion of stratified continuous sheaves to extend Gromov’s theory, 2. the notion of smooth stratified bundles to extend Eliashberg–Mishachev’s theory. A new feature is the role played by homotopy fiber sheaves. We show, in particular, that stratumwise flexibility of stratified continuous sheaves along with flexibility of homotopy fiber sheaves furnishes the parametric $h$-principle. We extend the Eliashberg–Mishachev holonomic approximation theorem to stratified spaces. We also prove a stratified analog of the Smale–Hirsch immersion theorem.

Wearable Optical Fiber Sensors for Biomechanical Measurement in Medical Rehabilitation: A Review

With the increasing demand for rehabilitation of the elderly population and patients with limb injuries, it is imperative to develop new wearable health monitoring system and assistive rehabilitation equipment. Optical fiber sensing has the advantages of light-weight, anti-electromagnetic interference, higher strain and elastic limit, safety and dependableness. It has been significantly utilized in engineering prospecting, building structure monitoring, and medical and health fields. At present, the application of optical fiber sensing in medical rehabilitation has been developed rapidly, however, the discussion and summary of its key theories and technologies are insufficient. This review details different types of optical fiber sensing mechanisms and devices, as well as the measurement of physical parameters using optical fiber sensors and application examples in the field of medical rehabilitation. This review systematically analyzes the advance of the sensitivity, flexibility, accuracy, and wearability of the optical fiber sensing in the monitoring of human body sign information. This review also discusses the challenges of making a new generation of optical fiber sensors that fit human joints, muscles, and rehabilitation equipment. Finally, this review provides a research direction for the realization of flexible, comfortable, safe, stable monitoring of human biomechanical parameters and real-time precise control of rehabilitation equipment in the future.

Topological supermodes in photonic crystal fiber

Topological states enable robust transport within disorder-rich media through integer invariants inextricably tied to the transmission of light, sound, or electrons. However, the challenge remains to exploit topological protection in a length-scalable platform such as optical fiber. We demonstrate, through both modeling and experiment, optical fiber that hosts topological supermodes across multiple light-guiding cores. We directly measure the photonic winding number invariant characterizing the bulk and observe topological guidance of visible light over meter length scales. Furthermore, the mechanical flexibility of fiber allows us to reversibly reconfigure the topological state. As the fiber is bent, we find that the edge states first lose their localization and then become relocalized because of disorder. We envision fiber as a scalable platform to explore and exploit topological effects in photonic networks.

Flexible High Energy Density Sodium Dual‐ion Battery with Long Cycle life

Flexible fiber‐shaped sodium dual‐ion batteries (FSDIBS) as a proof of concept are fabricated by using the hierarchical ReS2 nanosheets anchored on the carbon nanotube (ReS2@CNT) fiber as anode and graphite on the CNT as cathode. Owing to large interlayer spacing and weak layer coupling force of the ReS2 nanosheets and the anion accommodation of the graphite combined with good flexibility of the CNT fiber, the FSDIBS demonstrate outstanding electrochemical performances with high working voltage and high specific volumetric energy density, durable cycling life, and good flexibility. The FSDIBS show a specific discharge capacity of 97.8 mAh cm−3 at a current density of 630 mA cm−3 and high specific energy density of 25.12 mWh cm−3 (based on the whole volume of the two electrodes) and superb stability with a capacity retention of 91.8% even after bending for 2100 cycles. Moreover, a series of ex situ/in situ characterizations are verified that the reversible shuttles of the Na+ cations and anions between the anode and cathode are simultaneously occurred during the charge/discharge process.

High-performance salt-resistant solar interfacial evaporation by flexible robust porous carbon/pulp fiber membrane

Solar evaporation has emerged as an attractive technology to produce freshwater by utilizing renewable solar energy. However, it remains a huge challenge to develop efficient solar steam generators with good flexibility, low cost and remarkable salt resistance. Herein, we prepare flexible, robust solar membranes by filtration of porous carbon and commercial paper pulp fiber. The porous carbon with well-defined structures is prepared through controlled carbonization of biomass/waste plastics by eutectic salts. We prove the synergistic effect of porous carbon and paper pulp fiber in boosting solar evaporation performance. Firstly, the porous carbon displays a high light absorption, while the paper pulp fiber with good hydrophilicity effectively promotes the transport of water. Secondly, the combination between porous carbon and paper pulp fiber reduces the water vaporization enthalpy by 20%, which is important to significantly improve the evaporation performance. As a proof of concept, the porous carbon/paper pulp fiber membrane possesses a high evaporation rate of 1.8 kg m−2 h−1 under 1 kW m−2 irradiation. Thirdly, the good flexibility and mechanical property of paper pulp fiber enable the solar membrane to work well under extreme conditions (e.g., after 20 cycles of folding/stretching/recovery). Lastly, due to the super-hydrophilicity and superwetting, the hybrid membrane exhibits the exceptional salt resistance and long-term stability in continuous seawater desalination, e.g., for 50 h. Importantly, a large-scale solar desalination device for outdoor experiments is developed to produce freshwater. Consequently, this work provides a new insight into developing advanced flexible solar evaporators with superb performance in seawater desalination.

Nanomaterials-patterned flexible electrodes for wearable health monitoring: a review.

Electrodes fabricated on a flexible substrate are a revolutionary development in wearable health monitoring due to their lightweight, breathability, comfort, and flexibility to conform to the curvilinear body shape. Different metallic thin-film and plastic-based substrates lack comfort for long-term monitoring applications. However, the insulating nature of different polymer, fiber, and textile substrates requires the deposition of conductive materials to render interactive functionality to substrates. Besides, the high porosity and flexibility of fiber and textile substrates pose a great challenge for the homogenous deposition of active materials. Printing is an excellent process to produce a flexible conductive textile electrode for wearable health monitoring applications due to its low cost and scalability. This article critically reviews the current state of the art of different textile architectures as a substrate for the deposition of conductive nanomaterials. Furthermore, recent progress in various printing processes of nanomaterials, challenges of printing nanomaterials on textiles, and their health monitoring applications are described systematically.Graphical

A comprehensive review on natural fiber/nano‐clay reinforced hybrid polymeric composites: Materials and technologies

AbstractThe utilization of sustainable natural fibers as green filler/reinforcement material for producing polymeric composites is substantially improved due to increase in the perception of ecological safety and usage of biodegradable and renewable materials toward a green environment. These natural fibers are obtained from various sources and are reinforced in the polymer matrices to produce polymer matrix composites. However, the overall properties of these composites are low when compared to that of the synthetic fiber‐based composites due to poor interfacial bonding between the hydrophilic natural fiber and hydrophobic polymers. This deficiency can be addressed by incorporating the nano‐clay in the natural fiber composites. The nano‐clay added composites offer improved properties because of enrichment in the interfacial bonding between the matrix and reinforcement materials. Furthermore, the nano‐clay has the ability to increase both flexibility and rigidity of the natural fiber in a single step. This review article presents the information about different varieties and properties of natural fibers, polymers, nano‐clays, and nano‐clay added natural fiber composites with specific concern to their mechanical properties. This article also focuses on possible future paths for this emerging area of research.

Bio-inspired butterfly core-shaped photonic crystal fiber-based refractive index sensor

Light controllability, design flexibility, and non-linearity features of photonic crystal fiber (PCF) based surface plasmon resonance (SPR) sensor enable high sensitivity in the field of biosensing. Here, bio-inspired butterfly-core shaped microstructure fiber-based plasmonic sensor is proposed where circular air-holes are arranged to enhance the sensing performance. Butterfly shaped core is designed to confine the incident light into the core by preventing light scattering through the cladding and helps to excite surface electron of plasmonic metal layer. Chemically stable plasmonic material gold is used to produce the SPR phenomenon. The analyte detection layer and the plasmon layer are located externally on the PCF surface to make the detection process more feasible. The sensor performance is studied based on the finite element method (FEM), and the structural parameters are tuned to obtain maximum sensor performance. This modified core-based sensor exhibits the maximum wavelength sensitivity (WS) of 56,000 nm/RIU and the amplitude sensitivity (AS) of 1,584 RIU-1 for the x-polarized mode. It also shows an improved sensor resolution (SR) of 1.8 ×10−6 RIU, along with a decent figure of merit (FOM) of 691 RIU-1. Moreover, this sensor can detect analyte refractive indexes (RI) within a broad RI range of 1.33 to 1.42 in the visible to near-infrared wavelength range (450–2100 nm). Finally, the proposed sensor may have possible application to detect organic chemicals, food quality, and diseases with high accuracy due to outstanding sensitivity and linearity.

4-week eicosapentaenoic acid-rich fish oil supplementation partially protects muscular damage following eccentric contractions

BackgroundWe previously showed 8-week of fish oil supplementation attenuated muscle damage. However, the effect of a shorter period of fish oil supplementation is unclear. The present study investigated the effect of fish oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), for 4 weeks on muscular damage caused by eccentric contractions (ECCs) of the elbow flexors.MethodsTwenty-two untrained men were recruited in this double-blind, placebo-controlled, parallel design study and the subjects were randomly assigned to the EPA and DHA group (EPA and DHA, n = 11) and placebo group (PL, n = 11). They consumed either EPA 600 mg and DHA 260 mg per day or placebo supplement for 4 weeks prior to exercise. Subjects performed 60 ECCs at 100 % maximal voluntary contraction (MVC) using a dumbbell. Changes in MVC torque, range of motion (ROM), upper arm circumference, muscle soreness, echo intensity, muscle thickness, serum creatine kinase (CK), and interleukin-6 (IL-6) were assessed before exercise; immediately after exercise; and 1, 2, 3, and 5 days after exercise.ResultsROM was significantly higher in the EPA and DHA group than in the PL group immediately after performing ECCs (p < 0.05). No differences between groups were observed in terms of MVC torque, upper arm circumference, muscle soreness, echo intensity, and thickness. A significant difference was observed in serum CK 3 days after ECCs (p < 0.05).ConclusionsWe concluded that shorter period EPA and DHA supplementation benefits joint flexibility and protection of muscle fiber following ECCs.

NiS modified porous cotton-carbon fiber cloth with high conductivity and excellent electrocatalytic performance for DSSCs

Here we show a flexible porous cotton-carbon fiber cloth (PCC) film prepared by carbonizing natural cotton fiber cloth in argon atmosphere. This material not only has the flexibility and lightness of common carbon fiber, but also has good electrocatalytic activity and high conductivity, which is due to its one-dimensional cotton-carbon fiber skeleton with closely connected carbon particles, porous structure and large specific surface area. To improve the electrocatalytic performance of PCC, a layer of NiS was electrodeposited on the surface of PCC to form NiS/PCC electrode, which was used as high performance counter electrode of DSSC to instead of traditional FTO/Pt electrode. The photoelectric conversion efficiency of NiS/PCC reaches 6.80%, even slightly higher than that of Pt/FTO electrode (6.69%). In addition, this kind of material is cheap, flexible and light, all of which make it a potential low cost counter electrode material for large-scale application in DSSCs.

Numerical Investigation of a Short Polarization Beam Splitter Based on Dual-Core Photonic Crystal Fiber with As2S3 Layer.

A polarization beam splitter is an important component of modern optical system, especially a splitter that combines the structural flexibility of photonic crystal fiber and the optical modulation of functional material. Thus, this paper presents a compact dual-core photonic crystal fiber polarization beam splitter based on thin layer As2S3. The mature finite element method was utilized to simulate the performance of the proposed splitter. Numerical simulation results indicated that at 1.55 μm, when the fiber device length was 1.0 mm, the x- and y-polarized lights could be split out, the extinction ratio could reach −83.6 dB, of which the bandwidth for extinction ratio better than −20 dB was 280 nm. It also had a low insertion loss of 0.18 dB for the x-polarized light. In addition, it can be completely fabricated using existing processes. The proposed compact polarization beam splitter is a promising candidate that can be used in various optical fields.

Numerical Analysis of Midinfrared D-Shaped Photonic-Crystal-Fiber Sensor Based on Surface-Plasmon-Resonance Effect for Environmental Monitoring

An exciting prospect for the sensing community is the potential of midinfrared fiber sensors. Taking advantage of the design flexibility of photonic crystal fiber and the high excitation loss of gold layers, a high-performance midinfrared D-shaped sensor based on the surface-plasmon-resonance effect was designed and numerically investigated by a mature finite-element tool. Numerical results showed that the designed fiber is especially suitable for sensing. In an operating wavelength ranging from 2.9 to 3.6 μm, maximal wavelength sensitivity of 11,500 nm/refractive index unit (RIU) and a maximal refractive index (RI) resolution of 8.7 × 10−6 RIU were obtained by the wavelength-interrogation method when analyte RI varied from 1.36 to 1.37. Maximal amplitude sensitivity of 230 RIU−1 was obtained by the amplitude-interrogation method with a high linearity of 0.99519 and an adequate figure of merit of 142. Additionally, the sensor had good fabrication tolerance. Our sensor is a promising candidate for environmental monitoring.

Particle-modified polymeric cladding on glass optical fibers enhances radial light scattering

Radially light-emitting optical fibers are of increasing interest for applications in medicine, visible aesthetics, and environmental remediation. Optical fibers contain a light guiding core coated by protective polymer layers (cladding and coating), which assure both the strength and flexibility of the optical fiber. This paper examines the feasibility of scattering light radially from fibers by loading the fiber cladding with particle scattering centers during the optical fiber fabrication process. This work uses an in-line full-scale scalable facility to coat the fibers and control the polymer cladding and silica sphere. Loadings up to 2.0 wt. % of 500 nm silica particles on the cladding of the optical fiber led to an average of 80 times higher scattering for visible light and up to 30 times higher in the UVA wavelength range compared against cladding without particle modifications. This study illustrated the feasibility of fabricating broadband light scattering optical fibers for use with modified polymeric cladding.

Coaxial Triboelectric Nanogenerator and Supercapacitor Fiber-Based Self-Charging Power Fabric.

Although there has been rapid advancement in wearable electronics, challenges still remain in developing wearable and sustainable power sources with simple fabrication and low cost. In this work, we demonstrate a flexible coaxial fiber by fabricating a one-dimensional triboelectric nanogenerator (TENG) outside and a supercapacitor (SC) inside, which can not only harvest mechanical energy but also store energy in the all-in-one fiber. In such a coaxial fiber, carbon fiber bundles are utilized as the electrode material for the TENG as well as the active and electrode material for the SC. Meanwhile, silicone rubber serves as the separator between the SC and TENG, as the triboelectric material for the TENG, and as the encapsulation material for the whole fiber as well. Moreover, both SC and TENG exhibit good performance and stability, which ensures their long-term use in daily life. Because of the flexibility and durability of the carbon fiber and silicone rubber, the proposed coaxial fibers show great flexibility, which could be further knitted as cloth for sustainably powering wearable electronic devices. This work presents a promising platform for wearable electronics as well as smart textiles.

Shear Behavior of Variable-Depth Concrete Beams with Wound Fiber–Reinforced Polymer Shear Reinforcement

AbstractA novel shear reinforcing system, wound fiber–reinforced polymer (W-FRP), that capitalizes on the flexibility of carbon fiber to create durable reinforcement cages for geometrically optimiz...

Rheological and mechanical properties of hybrid fiber reinforced cement mortar

A new hybrid fiber system containing steel fiber, polyvinyl alcohol fiber (PVA fiber) and calcium carbonate (CaCO3) whisker was employed to further improve hardened properties and reduce engineering cost of cement mortar. In this paper, the rheological properties, flow rate and flow spread were measured to evaluate the workability of hybrid fiber reinforced mortar in fresh state. Mechanical strength and flexural toughness of mortars were tested in hardened state. The results indicated that, flowability of fresh hybrid fiber reinforced mortar decreased after substituting PVA fiber for steel fiber and further CaCO3 whisker for PVA fiber in mortar. This is mainly due to the flexibility of PVA fiber and large specific surface area of CaCO3 whisker. The hybrid fiber reinforced mortar shows promising mechanical strength and flexural toughness due to the multi-scale crack resistance formed by micro- and macro-fibers. M5 specimen (1.5% steel fiber+0.4%PVA fiber+1.0% CaCO3 whisker) exerts the best flexural performance and relatively higher compressive strength, exhibiting an obviously positive hybrid effect of fibers.

Synthesis and characterization of Fly ash /Wooden fiber reinforced Epoxy resin polymer composite

Composite is made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components. The mechanical property of a composite depends mainly on the physical and chemical properties of not only the resin, reinforcement used but also the hardener and solvent used. This paper highlights the experimental investigation on the effect of Acetone and Ethyl Alcohol solvent on composite laminates of teak wood powder and fly ash reinforcement with epoxy. The function of the solvent is to reduce the viscosity of the matrix to ensure the uniform distribution of the particulate reinforcement in the matrix upon stirring. Against this background, the present research work has been undertaken to explore the effect of acetone and ethyl alcohol solvent on wood powder and fly ash reinforced with epoxy. Hardener is added to the resin reinforcement mixture to ensure faster and uniform curing of the composite laminate at room temperature. But the hardener used (hy 951) being hydrophilic, absorbs moisture on exposure to atmosphere. The absorbed moisture adversely affects the curing of epoxy resin. This effect is more pronounced when the composite contains wood particles which also hydrophilic and absorbs moisture. Thus the present research also explores the effect of moisture on the curing properties of the composite. The present work thus aims to compare the effect of the ethanol and acetone solvent as well as the hardener properties on the flexibility of wood-flyash epoxy resin fiber reinforced polymer composites using SEM, XRD, FT-IR test results.

Experimental and numerical investigation of Long Glass Fiber Reinforced Polypropylene composite and application in automobile components

Due to the good mechanical performances and design flexibility of Long Glass Fiber Reinforced Polypropyl-ene (LGFRP) composite, it has been increasingly used in the automotive components, in which the LGFRP components are likely to sustain different strain rates loading during a crash event. This study aims to investigate the correlations between the LGFRP and strain rate, which will be applied to crash-worthiness and energy absorbing property analysis of a bumper beam under the longitudinal impact. Firstly, strain rate dependent material properties are determined, for which the experimental procedure is explained in detail on the tensile specimens of long glass fiber and polypropylene matrix based composite configurations. The gained experimental results provide the input parameters for a numerical analysis of specimens. The numerical results of properties are compared with those from tests. The constitutive model that fits for LGFRP is employed to crash-worthiness and energy absorbing property analysis of a bumper beam under the longitudinal impact. First Published Online: 17 May 2017

Rotating Triboelectric Generator Using Sliding Contact and Noncontact from 1D Fiber Friction

We design a continuously rotating triboelectric nanogenerator (CR-TENG) to minimize the rotation resistance for a rotor operating at small wind speeds (~3.5 m/s), and to maximize the efficiency of sliding contact as a one-dimensional (1D) fiber rather than two-dimensional contact areas. The CR-TENG harvests electrical energy (21.6 V and 0.6 μA) from a small wind with a speed of 3.5 m/s, which is easily generated in everyday life in spite of the small contact area (0.3 cm × 0.8 cm), which is due to the surface roughness and flexibility of the 1D fiber. Furthermore, a small-sized CR-TENG with a diameter of 2 cm can harvest electrical energy (5.1 V, 8.5 V, and 23.8 V, respectively) in artificial wind (10 m/s, 20 m/s, and 30 m/s) generated in a moving carrier, so a small-sized CR-TENG with improved mobility and highly integrated density may be realized.