Pair Of Fibers Research Articles

Adhesion anisotropy between contacting electrospun fibers.

The mechanical properties of electrospun fiber networks are critical in a range of applications from filtration to tissue engineering and are dependent on the adhesion between contacting fibers within the network. This adhesion is complex as electrospun networks exhibit a variety of contacts, including both cross-cylinder and parallel fiber configurations. In situ atomic force microscopy (AFM) was used to quantify the work of adhesion between a pair of individual electrospun polyamide fibers using controlled orientations and measurable contact areas. The work of adhesion was found to depend strongly on the fiber-fiber contact, with the separation of fibers in a parallel fiber configuration exhibiting considerably higher work of adhesion across a range of contact lengths than a cross-cylinder configuration. Our work therefore highlights direction-dependent adhesion behavior between electrospun fibers due to a suggested polymer chain orientation mechanism which increases net van der Waals interactions and indicates the variability of adhesion within a random electrospun fiber network.

Equalizer tap length requirement for mode group delay-compensated fiber link with weakly random mode coupling

The equalizer tap length requirement is investigated analytically and numerically for differential modal group delay (DMGD) compensated fiber link with weakly random mode coupling. Each span of the DMGD compensated link comprises multiple pairs of fibers which have opposite signs of DMGD. The result reveals that under weak random mode coupling, the required tap length of the equalizer is proportional to modal group delay of a single DMGD compensated pair, instead of the total modal group delay (MGD) of the entire link. By using small DMGD compensation step sizes, the required tap length (RTL) can be potentially reduced by 2 orders of magnitude.

Involvement of TRPC in the Slow Force Response Observed in Mouse Ventricular Myocytes

When cardiac muscle is stretched persistently, the contractile force slowly increases over several minutes. This phenomenon is termed by a slow force response (SFR). The SFR is due to a stretch-induced increase in Ca2+ influx, however, underlying mechanism remains unclear. The transient receptor potential, canonical (TRPC) channels are mechano-sensitive, non-selective cation channels. We hypothesized that activation of TRPC channels is involved in stretch-induced increase in Ca2+ influx in SFR. To test this hypothesis, mouse cardiac myocytes were isolated with collagenase, and a pair of computer-controlled piezo-positioned carbon fibers was attached to each cell-end. Cells were paced at 1 Hz and superfused in normal Tyrode solution. Passive and active forces were calculated from carbon fiber bending. Stretch was applied by moving carbon fiber positions to achieve 3-10 % increase in sarcomere length and maintained for 200 to 300 seconds to obtain SFR. At the plateu of SFR, the contractile force increased to 115.7 ± 3.7% (n = 16) of the value immediately after the stretch. Inhibition of TRPC channel with BTP-2 (10 μM) significantly reduced the magnitude of SFR (103.5 ± 1.0%, n = 8). It has been reported that activation of angiotensin II type 1 (AT1) receptor induces Ca2+ influx via TRPC channels. To reveal whether TRPC channels are activated secondarily by AT1 receptor activated by strech, we tested the effect of Olmesartan, an AT1 receptor inhibitor, in SFR. Olmesartan (10 μM) also reduced the magnitude of SFR (101.1 ± 2.4%, n = 8). These results suggest that stretch-induced activation of AT1 receptors leads to increase in Ca2+ influx via TRPC channels in SFR.

Hofer geometry and cotangent fibers

For a class of Riemannian manifolds that include products of arbitrary compact manifolds with manifolds of nonpositive sectional curvature on the one hand, or with certain positivecurvature examples such as spheres of dimension at least 3 and compact semisimple Lie groups on the other, we show that the Hamiltonian diffeomorphism group of the cotangent bundle contains as subgroups infinite-dimensional normed vector spaces that are bi-Lipschitz embedded with respect to Hofer’s metric; moreover these subgroups can be taken to consist of diffeomorphisms supported in an arbitrary neighborhood of the zero section. In fact, the orbit of a fiber of the cotangent bundle with respect to any of these subgroups is quasi-isometrically embedded with respect to the induced Hofer metric on the orbit of the fiber under the whole group. The diffeomorphisms in these subgroups are obtained from reparametrizations of the geodesic flow. Our proofs involve a study of the Hamiltonian-perturbed Floer complex of a pair of cotangent fibers (or, more generally, of a conormal bundle together with a cotangent fiber). Although the homology of this complex vanishes, an analysis of its boundary depth yields the lower bounds on the Lagrangian Hofer metric required for our main results.

Paper microfluidic extraction and direct smartphone-based identification of pathogenic nucleic acids from field and clinical samples

A rapid, paper microfluidic- and smartphone-based protocol was developed for the extraction and direct fluorescent identification of the nucleic acids of Salmonella Typhimurium from field and clinical samples. Initially, liquid samples (10% diluted) from fresh poultry packaging were loaded on the paper chips and were lysed with Tris–EDTA (TE) buffer. Nucleic acids from the lysed samples were eluted through the paper channel with TE buffer and the paper channel was excised into three pieces for the further polymerase chain reaction (PCR) assay. The extraction efficiency was determined by measuring fluorescence reflectance with either a benchtop optical detection system (consisting of an LED light source, a pair of optical fibers, and a miniature spectrophotometer, all built on micro-positioning stages) or a smartphone-based fluorescent microscope (in-house fabricated). The limit of detection of Salmonella Typhimurium in 10% poultry packaging liquid with cellulose paper was 103 CFU mL−1, while that extracted with nitrocellulose paper was 104 CFU mL−1 (as determined by both PCR and fluorescence reflectance). Cellulose channels proved more appropriate for measuring low and very high concentrations of pathogen DNA, while nitrocellulose proved better for analysing the mid-range concentrations. We observed that DNA migrated through nitrocellulose at a faster rate and further than through cellulose due to charge–charge repulsion between nitrocellulose and DNA (both negatively charged), thus contributing to consistent and efficient extraction. We tested the efficiency of Salmonella extraction from 10% poultry packaging liquid, 10% whole blood, and 10% fecal samples, and obtained comparable extraction efficiency, as confirmed by smartphone-based direct fluorescent detection. This protocol is suitable for the direct detection of total bacteria count in a dirty sample (when specificity is not necessary) as well as determining extraction efficiency. This protocol is compatible with PCR, to provide specific information about the type of pathogen present in sample.

Comparative myoanatomy of Echinoderes (Kinorhyncha): a comprehensive investigation by CLSM and 3D reconstruction.

IntroductionKinorhyncha is a clade of marine invertebrate meiofauna. Their body plan includes a retractable introvert bearing rings of cuticular spines, and a limbless trunk with distinct segmentation of nervous, muscular and epidermal organ systems. As derived members within the basal branch of Ecdysozoa, kinorhynchs may provide an important example of convergence on the evolution of segmentation within one of three bilaterian superclades. We describe the myoanatomy of Echinoderes, the most specious kinorhynch genus, and build upon historical studies of kinorhynch ultrastructure and gross morphology. This is the first multi-species comparison of a complete organ system by confocal microscopy and three-dimensional reconstruction within Kinorhyncha.ResultsMyoanatomy of adult Echinoderes is composed of the following: Head with two mouth cone circular muscles, nine pairs of oral style muscles, ten introvert retractors, one introvert circular muscle, and fourteen introvert circular muscle retractors; Neck with one circular muscle; Trunk showing distinct pairs of ventral and dorsal muscles within segments 1–10, dorsoventral muscles within segments 3–10, diagonal muscles within segments 1–8, longitudinal fibers spanning segments 1–9, three pairs of terminal spine muscles, and one pair of male penile spine muscles; Gut showing a pharynx with ten alternating rings of radial and circular muscle fibers enclosed in a complex sheath of protractors and retractors, an orthogonal grid of longitudinal and circular fibers surrounding the intestine, and paired hindgut dilators.ConclusionsMyoanatomy is highly conserved between species of Echinoderes. Interspecific variation is observed in the arrangement and number of introvert fibers and the composition of pharyngeal muscles. Segmented trunk musculature facilitates the movements of articulated cuticular plates along the anterior-posterior axis. Intersegmental muscle fibers assist with dorsoventral and lateral trunk movements. Protractors, retractors and circular muscles coordinate eversion and retraction of the introvert and mouth cone, and relocation of the pharynx during locomotion and feeding behaviors. Pairs of posterior fibers suggest independent movements of terminal spines, and male penile spines. Within Scalidophora, myoanatomy is more similar between Kinorhyncha and Loricifera, than either group is to Priapulida. Kinorhynch myoanatomy may reflect a convergent transition from vermiform to segmented body plans during the early radiation of Ecdysozoa.

Interfaces within flax fibre bundle: Experimental characterization and numerical modelling

In natural fibre based-composites, the interfaces within the fibre bundles are not as well described as those between fibres and classical polymer matrices. To compensate for this lack of information, which is however of great importance when trying to model the composite behaviour, morphological and mechanical characterization of the middle lamella present between flax fibres has been carried out. The interfacial strength of the pectic cement was found to be very low compared with that of the fibre/matrix interface. Assuming this fibre/fibre interface to be a cohesive zone material and using the experimental results obtained on pairs of fibres, a model has been developed at the scale of the fibre and applied to study numerically the tensile properties of bundles. The results of the simulations were in agreement with the experimental data obtained on bundles, both leading to a mean bundle strength of 500 MPa.

Lateral force sensing system based on different photonic crystal fibres

Four types of photonic crystal fibres (PCFs) with different structures and values of birefringence have been evaluated and cross-compared in terms of their corresponding characteristics and sensitivities to lateral force (or pressure), considering this as a function of fibre orientation and the magnitude of the applied external force, as the basis of an all-fibre sensor system. In addition, the force/pressure sensitivities of different pairs of these PCFs when they were fusion-spliced together were evaluated and cross-compared. To obtain an optimum output from these systems, a polarization controller is used in a fibre loop mirror configuration to ensure that a fusion-spliced pair of PCFs is created having the same birefringence angle.The results obtained show that PCFs of low birefringence (Low-Bi) are more sensitive than those of high birefringence (Hi-Bi), although the former require a greater length to achieve a similar effect due to the birefringence. Compared to conventional, non-PCF Hi-Bi fibres (e.g. Panda and Bow-Tie fibres), PCFs demonstrate a much lower temperature sensitivity, allowing them to be well suited to measuring force, pressure and mass in real time (when the temperature is varying) by using a fibre loop mirror (FLM) configuration. In addition, the results obtained show that the sensitivity of the fusion-spliced fibre pairs is lower than that of a single PCF with low and medium birefringence, but more sensitive than that of a single PCF with high birefringence.

Medial Patellofemoral Ligament Influence on Patellofemoral Joint Kinematics: An In-Vitro Analysis

Lyon Ortho Clinic, Lyon, France Patellar stability is an important component for a correct kinematic behavior of the knee. Patellofemoral (PF) maltracking can lead to joint disorders associated with pain and mobility alterations. The goal of this work was to study the morphology of the Medial Patellofemoral Ligament (MPFL) and its effect on knee kinematics. Evaluation of patello-femoral joint pathology and efficacy of treatment is challenged by lack of consensus on its kinematics [1]. Specifically damages to the Medial Patello-femoral Ligament (MPFL) has been suggested to be the essential lesion in lateral patellar dislocation [2,3]. While MPFL reconstruction has better results compared to previous procedures, a recent systematic review advocated a greater knowledge of MPFL behavior to prevent alteration of patello-femoral kinematics, joint compression and long term chondral degeneration after reconstruction [4]. The objective of this study was to analyse the morphology of the MPFL and its influence on patello-femoral kinematics with reference to the trochlea. A kinematic study on six cadaveric knees, using a non-image based navigation system, under an axial quadriceps load of 60 N, in MPFL-intact and MPFL-deficient state, with and without a laterally directed load of 25 N at 0°, 30°, 60° and 90°, was performed. The MPFL was isolated from the Medial Menisco-Tibial Ligament, the navigation system was used to define its insertions, four representative fibers and trochlear surface. The MPFL femoral insertion exhibited a high intra-group variability with a mean surface area of 36.5 ± 11.74 mm2. During flexion, the superior decussation were almost isometric, while the inferior two bundles moved closer significantly. The medial shift between 20°-25° of tibial flexion in the MPFL intact, was absent in the MPFL-deficient state and the patella lateralized even without a laterally directed load. The patella did not exhibit any medial tilt between 20°-25° in the current study. A laterally directed load significantly increased the lateral patellar shift after MPFL dissection, peaking at 30° and 60°. The variable femoral insertion of the MPFL is in agreement with previous literature. The isometric insertion points of the superior fiber pair can be compared to Victor et. al’s isometric central bundle. No fibers exhibited kinematic behavior comparable to Victor et. al’s cranial bundle, which probably represents an aponeurosis for the insertion of the VMO. The current study shows a statistically significant lateral shift and tilt in this state. The peak patellar shift under load between 30° and 50° in MPFL deficient state probably reflects the peak strain on the MFPL in this range of knee flexion These comparisons clarify that the MFPL has an aponeurotic nature that works as a restraint during motion, with an active role under stress, but low role during neutral knee flexion.

An Optical Fiber-Based Gating Device for Prospective Mouse Cardiac MRI

Prospective synchronization of MRI acquisitions on living organisms involves the monitoring of respiratory and heart motions. The electrocardiogram (ECG) signal is conventionally used to measure the cardiac cycle. However, in some circumstances, obtaining an uncorrupted ECG signal recorded on small animals with radio frequency (RF) pulses and gradient switching is challenging. To monitor respiratory motion, an air cushion associated with a pressure sensor is commonly used but the system suffers from bulkiness. For many applications, the physiological gating information can also be derived from an MR navigated signal. However, a compact device that can simultaneously provide respiratory and cardiac information, for both prospective gating and physiological monitoring, is desirable. This is particularly valid since small volume coils or dedicated cardiac RF coil arrays placed directly against the chest wall are required to maximize measurement sensitivity. An optic-based device designed to synchronize MRI acquisitions on small animal's respiratory and heart motion was developed using a transmit-receive pair of optical fibers. The suitability of the developed device was assessed on mice ( n = 10) and was based on two sets of experiments with dual cardiac and respiratory synchronization. Images acquired with prospective triggering using the optical-based signal, ECG, and the pressure sensor during the same experiment were compared between themselves in the first set. The second set compared prospective technique using optical-based device and ECG to a retrospective technique. The optical signal that was correlated to both respiratory and heart motion was totally unaffected by radiofrequency pulses or currents induced by the magnetic field gradients used for imaging. Mice heart MR images depict low-visible motion artifacts with all sensors or techniques used. No significant SNR differences were found between each series of image. Full fiber-optic-based signal derived from heart and respiratory motion was suitable for prospective triggering of heart MR imaging. The fiber optic device performed similarly to the ECG and air pressure sensors, while providing an advantage for imaging with dedicated cardiac array coils by reducing bulk. It can be an attractive alternative for small animal MRI in difficult environments such as limited space and strong gradient switching.

An intensity-modulated optical fiber sensor with concave mirror for measurement of displacement

Two fiber intensity-modulated sensors are investigated and used in number of applications, including those in military, industry, biomedical, and aerospace. A common form of two fiber intensity-modulated optical fiber sensor performs its measurement by making use of a pair of straight optical fibers with a plane reflector. The reflected optical intensity is a function of distance between fiber tips and plane reflector as well as refractive index of the medium. This paper describes an alternative sensing structure with a concave reflector instead of a plane reflector and demonstrates the derivation of the geometric mathematical model for analyzing its sensing characteristics. The mathematical model shows that the blind region is minimized, when the plane reflector is replaced by a concave reflector. Such type of optical sensor can be used where space required for the measurement is the major limitation. Experimental results obtained confirm the model.

Twisted pair of optic fibers for background removal in radiation fields

In many situations in which an optic fiber carries a signal through a radiation field, an unwanted background signal is produced consisting of fluorescent and/or Cerenkov light. This presents a major problem in the measurement of the light signal, for example, in scintillation dosimetry of medical therapeutic beams. In this paper, we demonstrate a new method of measuring and removing the background signal through the use of a twisted pair of optic fibers. The twisted pair consists of a fiber carrying the scintillation signal that is twisted with a second optic fiber to form a double helix. The two twisted fibers will experience the same radiation environment provided the periodicity of the twist is correlated to the dose rate gradient. An expression for the required twist periodicity is presented. A scintillation dosimeter with a twisted pair optic fiber was tested in a megavoltage beam and found to accurately measure its beam characteristics. The twisted pair approach is not restricted to medical applications and can be used in many situations in which optical signals are carried through radiation fields.

High performance architecture design for large scale fibre-optic sensor arrays using distributed EDFAs and hybrid TDM/DWDM

A distributed amplified dense wavelength division multiplexing (DWDM) array architecture is presented for interferometric fibre-optic sensor array systems. This architecture employs a distributed erbium-doped fibre amplifier (EDFA) scheme to decrease the array insertion loss, and employs time division multiplexing (TDM) at each wavelength to increase the number of sensors that can be supported. The first experimental demonstration of this system is reported including results which show the potential for multiplexing and interrogating up to 4096 sensors using a single telemetry fibre pair with good system performance. The number can be increased to 8192 by using dual pump sources.

Effect of Braking Speed on Frictional Properties of Short Fiber C/C-SiC Brake Materials and Grey Cast Iron

Short fiber C/C-SiC brake materials were prepared by dipping the fibers in resin, chopping, warm pressing, and pyrolyzing, followed by a liquid silicon infiltration process. The effect of braking speed (initial braking speed) on the frictional properties of a pair of short fiber C/C-SiC brake materials and grey cast iron (HT250) (C/C-SiC-HT250) was investigated. The results indicated that the average friction coefficient of the C/C-SiC-HT250 increased to the maximum value at 10 m/s and then decreased with an increase in braking speed. The wear rate of the C/C-SiC increased with increasing braking speed when it was lower than 10 m/s and decreased when it was higher than 10 m/s. The wear was the result of the brittle fracture of asperities when the braking speed was lower than 10 m/s and induced granular debris. The wear for the tough cutting by C/C-SiC asperities or hard phase when the braking speed was higher than 10 m/s and resulted in ribbon debris. When the braking speed was higher than 20 m/s, the texture of the friction surface of the HT250 changed, which would affect the tribological properties.

Evaporation of Drops on Two Parallel Fibers: Influence of the Liquid Morphology and Fiber Elasticity

We investigate experimentally the evaporation of liquid accumulated on a pair of parallel fibers, rigid or flexible. The liquid wetting the fibers can adopt two distinct morphologies: a compact drop shape, whose evaporation dynamics is similar to that of an isolated aerosol droplet, or a long liquid column of constant cross-section, whose evaporation dynamics depends upon the aspect ratio of the column. We thus find that the evaporation rate is constant for drops, while it increases strongly for columns as the interfiber distance decreases, and we propose a model to explain this behavior. When the fibers are flexible, the transition from drops to columns can be induced by the deformation of the fibers because of the capillary forces applied by the drop. Thus, we find that the evaporation rate increases with increasing flexibility. Furthermore, complex morphology transitions occur upon drying, which results in spreading of the drop as it evaporates.

Effect of azelnidipine and amlodipine on single cell mechanics in mouse cardiomyocytes

Azelnidipine and amlodipine are dihydropyridine-type Ca2+ channel blockers for the treatment of hypertension. Although these drugs have high vasoselectivity and small negative inotropic effects in vivo, little is known regarding their direct effects on cellular contractility without humoral regulation or the additive effects of these drugs with other antihypertensive drugs on myocardial contractility. To investigate the effects of Ca2+ channel blockers on single cell mechanics, mouse cardiomyocytes were enzymatically isolated, and a pair of carbon fibers was attached to opposite cell-ends to stretch the cells. Cells were paced at 4Hz superfused in normal Tyrode solution at 37°C. Cell length and active/passive force calculated from carbon fiber bending were recorded in 6 different preload conditions. Slopes of end-systolic force—length relation curves (maximum elastance) were measured as an index of contractility before and after drugs were administered. Azelnidipine at 10nM and 100nM did not change maximum elastance, while amlodipine at 100nM did decrease maximum elastance. The combination of RNH-6270 (active form of angiotensin II receptor blocker, olmesartan, 10nM) and either amlodipine (10nM) or azelnidipine (10nM) did not affect maximum elastance. Although both amlodipine and azelnidipine can be used safely at therapeutically relevant concentrations even in combination with olmesartan, the present results suggest that azelnidipine has a less negative inotropic action compared to amlodipine.

<em>In-situ</em> Tapering of Chalcogenide Fiber for Mid-infrared Supercontinuum Generation

Supercontinuum generation (SCG) in a tapered chalcogenide fiber is desirable for broadening mid-infrared (or mid-IR, roughly the 2-20 μm wavelength range) frequency combs(1, 2) for applications such as molecular fingerprinting, (3) trace gas detection, (4) laser-driven particle acceleration, (5) and x-ray production via high harmonic generation. (6) Achieving efficient SCG in a tapered optical fiber requires precise control of the group velocity dispersion (GVD) and the temporal properties of the optical pulses at the beginning of the fiber, (7) which depend strongly on the geometry of the taper. (8) Due to variations in the tapering setup and procedure for successive SCG experiments-such as fiber length, tapering environment temperature, or power coupled into the fiber, in-situ spectral monitoring of the SCG is necessary to optimize the output spectrum for a single experiment. In-situ fiber tapering for SCG consists of coupling the pump source through the fiber to be tapered to a spectral measurement device. The fiber is then tapered while the spectral measurement signal is observed in real-time. When the signal reaches its peak, the tapering is stopped. The in-situ tapering procedure allows for generation of a stable, octave-spanning, mid-IR frequency comb from the sub harmonic of a commercially available near-IR frequency comb. (9) This method lowers cost due to the reduction in time and materials required to fabricate an optimal taper with a waist length of only 2 mm. The in-situ tapering technique can be extended to optimizing microstructured optical fiber (MOF) for SCG(10) or tuning of the passband of MOFs, (11) optimizing tapered fiber pairs for fused fiber couplers(12) and wavelength division multiplexers (WDMs), (13) or modifying dispersion compensation for compression or stretching of optical pulses.(14-16.)

Highly Scalable Amplified Hybrid TDM/DWDM Array Architecture for Interferometric Fiber-Optic Sensor Systems

We present a distributed amplified hybrid dense wavelength division multiplexing (DWDM) and time division multiplexing (TDM) array architecture for large scale interferometric fiber-optic sensor array systems. This architecture employs a distributed Erbium doped fiber amplifier (EDFA) scheme to decrease the distribution loss among multiplexed wavelengths, and employs TDM at each wavelength to increase the total number of sensors that can be supported. The first experimental demonstration of this system is reported including results which show the potential for multiplexing and interrogating up to 4096 sensors using a single telemetry fiber pair with good system performance. The number of interrogation sensors could be further increased by increasing the number of wavelength channels. These architectures would be of great importance in the application of systems requiring very large number of sensors with limited telemetry cabling.

Mechanical properties of interfaces within a flax bundle—Part II: Numerical analysis

In the experimental part of this study, mechanical tests and microscopic observations were performed on pairs of flax fibres to characterize the middle lamella at the interface between the two fibres. The main objective of this second part has been to study numerically the tensile strength of the bundles, taking into account the mechanical behaviour of the middle lamella. The bundle geometry was reconstructed on the basis of optical micrographs, and used a staggered longitudinal arrangement of the fibres. A bilinear cohesive zone model was used to describe the mechanical behaviour of the middle lamella. A first model with a pair of fibres was developed in order to calibrate the main parameters of the non-linear algorithm and to validate the scale-up law used. Then a second model, representing a bundle of seven fibres, was developed to analyse the tensile strength of the bundle when the gauge length varies. Numerical simulations were carried out using appropriate contact elements of ANSYS to model the interface behaviour. Comparisons between numerical results and experimental values show good agreement and prove the relevance of this study.

Efficiency of Optical Fiber Communication for Dissemination of Information within the Power System Network.

Within the power system network, consistent domestic communications are essential to ensure safety, security and control of the power system equipments. Such communications customarily have been provided by methods such as power line carrier and microwave radio systems but are more recently being supplemented or replaced by Fiber optics. This paper focuses on the practical steps to review and evaluation on the effectiveness of using Fiber optic cable technology in the domestic communication of power system network. With the advent of information and communication technology, it has become obvious that Fiber optic is replacing this crude method of data communication. It offers a unique solution to ever increasing demand for bandwidth because of its remarkably high capacity for carrying data, and guaranteed consistency of signal transmission over the entire transmission network. A pair of Fiber has the ability to carry over eight thousand simultaneously voice channels and has high immunity to electromagnetic interference. All these advantages made it extra-ordinarily useful in data communication like Internet, multimedia and scada applications. Over short or long distances, video, audio and data signals arrive at their destination in the same perfect quality as they originated and also assures security of data being transmitted.