Fiber Radius Research Articles

On rotationally driven nonlinear inclined polymeric jet with gravity effect

<abstract> We consider rotationally driven nonlinear polymeric fiber jet, whose centerline is in an inclined plane, in the presence of gravity force. An empirical viscosity model is used for the polymeric fluid flow to investigate properties of the rotating inclined polymeric fiber jet. The aim of the study is to understand properties of such inclined fiber jet shape, which can be due to orientation change of an orifice in a rotating spinneret that generates such jet. Perturbation, asymptotic, scaling and numerical techniques are used to determine the nonlinear steady solutions for the jet quantities for different values of the parameters due to gravity, rotation, viscosity, surface tension and relaxation time. In contrast to the horizontal jet case, presence of gravity and jet inclination increase values of the jet speed, strain rate, stretching rate and the centerline curvature and decrease the value of the jet radius and more so with increasing the arc length, gravity, rotation rate and the relaxation time. However, a non-inclined jet with no imposed restriction on its shape and in presence of gravity leads to smaller fiber radius and larger speed as compared to the ones for inclined jet case. </abstract>

Wavelength-Selective Transmittance in Nano Structure

Purpose : In order to investigate the cause of the change in light transmittance according to the diameter, the optical properties of incident light and transmitted light were analyzed. The change in transmittance of the central wavelength according to the collagen fiber diameter was analyzed. Methods : In order to analyze the characteristics of transmitted light, a 3D simulator of the FDTD method was used. The incident light was set to a Gaussian Modulated Continuous Wave with the center wavelength of 589 nm and the wavelength range of 300 to 900 nm.Results : Even when the radius of the collagen fiber was changed, there was no significant difference in the ratio of the area occupied by the collagen fiber to the simulation space. However, as the diameter of collagen fibers increased, the sum of the transmittance intensity decreased. It increased at 20 to 30 nm of the diameter and rapidly decreased at 30 nm again. Analyzing the optical characteristics according to the change of the central wavelength, it was found that the wavelength at which the transmittance became lowered was not constant depending on the collagen fiber diameter.Conclusion : In the simulation of a real collagen-like structure, selective transmission or absorption occurs at a specific wavelength regardless of the range of central wavelength. It is expected that there will be applied to the selective light beam that runs high-efficiency optical devices.

A self-consistent approach for the acoustical modeling of vegetal wools

Vegetal wools have the capacity to store atmospheric carbon dioxyde, one of the main gases responsible for climate change. So, these insulating materials are used as key elements for green buildings. Moreover, vegetal wools present high sound absorption level performances contributing to the acoustic comfort of indoor living spaces. These properties are directly related to the morphology and the size of their vegetal fibres. Thus, to take their microstructural specificities into account for the modeling of their sound absorption properties, a micro-macro homogenization approach based on a cylindrical geometry is developed. This modeling method, based on a mix between Homogenization of Periodic Media (HPM) and Self-Consistent Method (SCM), is called SCMcyl. The macroscopic behaviour laws of materials are rigorously obtained by using HPM. Then, the SCM leads to the establishment of two possible analytical solutions (a velocity approach v and a pressure approach p) under the fundamental assumption of the energy equivalence between a generic cylindrical inclusion, representative of the vegetal wools physical and geometrical properties at microscopic scale, and the homogeneous equivalent medium at the macroscopic scale. The two modeling approaches developed in this paper, SCMcyl−v and SCMcyl−p, can be used to determine the sound absorption of fibrous materials using only two parameters, an equivalent fibre radius value and the material porosity. Finally, these solutions are validated for the vegetal wools case by comparison with experimental measurements.

Slow-Light-Enhanced Optical Imaging of Microfiber Radius Variations with Subangstrom Precision

Optical fibers play a key role in many different fields of science and technology. In particular, fibers with a diameter of several micrometers are intensively used in photonics. For these applications, it is often important to precisely know and control the fiber radius. Here, we demonstrate a novel technique to determine the local radius variation of a 30-micrometer diameter silica fiber with sub-\AA ngstr\"om precision with axial resolution of several tens of micrometers over a fiber length of more than half a millimeter. Our method relies on taking an image of the fiber's whispering-gallery modes (WGMs). In these WGMs, the speed of light propagating along the fiber axis is strongly reduced. This enables us to determine the fiber radius with a significantly enhanced precision, far beyond the diffraction limit. By exciting different axial modes, we verify the precision and reproducibility of our method and demonstrate that we can achieve a precision better than 0.3 \AA. The method can be generalized to other experimental situations where slow light occurs and, thus, has a large range of potential applications in the realm of precision metrology and optical sensing.

A micromechanical crack opening displacement model for fiber-reinforced ceramic-matrix composites considering matrix fragmentation

In this paper, a micromechanical approach is developed to predict crack opening displacement (COD) of fiber-reinforced ceramic-matrix composites (CMCs) under tensile loading considering matrix fragmentation. The shear-lag model is adopted to obtain the micro stress filed of the damaged CMCs with matrix fragmentation and fiber/matrix interface debonding. The CODs of three different types of matrix fragmentation lengths, i.e., long, medium, and short fragmentation, are obtained considering relative slip between the fiber and the matrix. Relationships between composite constituent properties, COD, and matrix fragmentation are established. Effects of composite constituent properties (i.e., fiber volume fraction, fiber radius, and fiber and matrix Young’s modulus), matrix fragmentation length, and interfacial shear stress on crack opening displacement (COD), crack opening stress (COS), interface debonding ratio (IDR), interface complete debonding stress (ICDS), and axial fiber and matrix displacements (AFD/AMD) at the crack plane are analyzed. Experimental COD, COS, ICDS, IDR, AFD, and AMD at the crack plane of Hi-Nicalon™ SiC/SiC minicomposite are predicted for different matrix fragmentation lengths. The COD increased with applied stress, and can be divided into two regions corresponding to the interface partial and complete debonding, and the increasing rate of COD in the partial interface debonding region was much higher than that in the complete interface debonding region. When the matrix fragmentation length increased, the difference of COD was very small in the interface partial debonding region, however, in the interface complete debonding region, the COD increased with matrix fragmentation length, the COS, ICDS, AFD, and AMD increased.

Coupling between guided modes of two parallel nanofibers

We study the coupling between the fundamental guided modes of two identical parallel nanofibers analytically and numerically. We calculate the coefficients of directional coupling, butt coupling, and self coupling as functions of the fiber radius, the light wavelength, and the fiber separation distance. We show that, due to the symmetry of the system, a mode of a nanofiber with the principal quasilinear polarization aligned along the axis joining the nanofibers or the perpendicular axis is coupled only to the mode with the same corresponding principal polarization of the other nanofiber. We find that the effects of the butt coupling and the self coupling on the power transfer are significant when the fiber radius is small, the light wavelength is large, or the fiber separation distance is small. We show that the power transfer coefficient may achieve a local maximum or become zero as the fiber radius, the light wavelength, or the fiber separation distance varies.

Estimation Models for the Refractive Index Response Curve of EFBGs

Estimation models for the surrounding refractive index response of EFBGs were developed from computer simulations and tested on experimental data. Numerical simulations were used to investigate the fundamental core mode’s effective refractive index dependence with the fiber radius and the surrounding refractive index. An empirical mathematical model was developed upon the simulation results, and it was used to derive the estimation models. The response curve is estimated from a reference calibration curve using two different approaches: interpolation and extrapolation. The interpolation is performed using the wavelength response of the EFBGs at two different surrounding refractive index values. Then, the response curve is obtained solving a simple pair of linear equations. The extrapolation is performed using the wavelength shift observed during the etching process, which is used to derive a multiplicative factor for the calibration curve. The response curves estimated by the model were compared with the experimental results, showing good agreement within the experimental uncertainties. Considering the surrounding refractive index ranging from 1.333RIU to 1.458RIU, with the sensors’ response ranging from 1544.84nm to 1552.70nm, the maximum deviation between the estimation and the experimental results were 0.26nm and 0.41nm, and the maximum standard deviation were 0.03nm and 0.05nm, respectively for interpolation and extrapolation.

A micromechanical vibration damping model of fiber-reinforced ceramic–matrix composites considering interface debonding

A micromechanical vibration damping model of fiber-reinforced ceramic–matrix composites is developed considering interface debonding. The relationship between the stress-dependent composite damping and interface debonding is established. Effects of material properties and damage-related parameters on the vibration damping of fiber-reinforced CMCs are discussed. Experimental vibration damping with interface debonding of C/SiC composites is predicted. When the vibration frequency increases from f = 1–5 Hz, the vibration damping decreases due to the increasing dynamic interfacial shear stress and low frictional dissipated energy in the debonding region. The composite vibration damping decreases with increasing fiber volume, matrix crack spacing and interface shear stress, and increases with fiber radius and fiber elastic modulus. When the interface debonding energy increases, the vibration damping decreases when the interface partial debonding and approaches the same value when the interface complete debonding, and the vibration stress for complete interface debonding increases.

Clot formation, lysis and ultrastructure in patients with acute phase myocardial infarction

Abstract Background/Introduction Patients with established coronary artery disease have impaired clot structure and lysis. Prior research has compared patients with myocardial infarction to those with stable coronary artery disease (without a healthy reference), or patients after myocardial ischemia. The role of clot structure in the acute phase of the disease is unknown. Purpose Investigate clot structure in the acute phase of myocardial infarction (AMI) compared to healthy controls. Methods Plasma clots from AMI patients (within 12 hours of symptoms onset) or healthy controls were analyzed by turbidity and lysis. Clot pore size was determined by permeation. Clot ultrastructure was determined by confocal and scanning electron microscopy. Average fiber radius and protofibril packing were investigated by turbidimetry. Results Analysis on clot formation, using turbidity, showed increased lag time (24%, p&amp;lt;0.05), suggesting changes in protofibril packing and increased fiber size for AMI patients compared to controls. Additionally, AMI clots formed more quickly as evidenced by average rate of clotting (2.9-fold increase, p&amp;lt;0.001) and time to maximum absorbance (38% decrease, p&amp;lt;0.0001). Decreased plasminogen in AMI patients (23%, p&amp;lt;0.05) had strong effects on clot lysis, including increased time to half lysis (1.72-fold, p&amp;lt;0.0001) and increased time to maximum lysis rate (7.96-fold, p&amp;lt;0.0001). Taken together, these results suggest that AMI patients form less porous clots made from densely packed fibers with decreased numbers of protofibrils, which was confirmed using permeation (1.05-fold decrease, p&amp;lt;0.0001), confocal (Figure 1) and scanning electron microscopy (46% increase, p&amp;lt;0.0001), and turbidimetry (16% decrease, p&amp;lt;0.05) respectively. Conclusions Plasma from patients with AMI form denser and less permeable clots that lyse more slowly than healthy controls. These data show marked abnormalities in clot ultrastructure that contribute to the high risk of thrombosis during the acute phase of myocardial infarction, which has not shown in previous investigations. Figure 1. Confocal microscopy of AMI vs. controls Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): Jagiellonian University Medical College to G.G. (N41/DBS/000096) and BHF Programme Grant to S.R.B. and R.A.S.A. (RG/18/11/34036).

Entrainment of particles during the withdrawal of a fibre from a dilute suspension

Abstract

Skeleton optimization of neuronal morphology based on three-dimensional shape restrictions

BackgroundNeurons are the basic structural unit of the brain, and their morphology is a key determinant of their classification. The morphology of a neuronal circuit is a fundamental component in neuron modeling. Recently, single-neuron morphologies of the whole brain have been used in many studies. The correctness and completeness of semimanually traced neuronal morphology are credible. However, there are some inaccuracies in semimanual tracing results. The distance between consecutive nodes marked by humans is very long, spanning multiple voxels. On the other hand, the nodes are marked around the centerline of the neuronal fiber, not on the centerline. Although these inaccuracies do not seriously affect the projection patterns that these studies focus on, they reduce the accuracy of the traced neuronal skeletons. These small inaccuracies will introduce deviations into subsequent studies that are based on neuronal morphology files.ResultsWe propose a neuronal digital skeleton optimization method to evaluate and make fine adjustments to a digital skeleton after neuron tracing. Provided that the neuronal fiber shape is smooth and continuous, we describe its physical properties according to two shape restrictions. One restriction is designed based on the grayscale image, and the other is designed based on geometry. These two restrictions are designed to finely adjust the digital skeleton points to the neuronal fiber centerline. With this method, we design the three-dimensional shape restriction workflow of neuronal skeleton adjustment computation. The performance of the proposed method has been quantitatively evaluated using synthetic and real neuronal image data. The results show that our method can reduce the difference between the traced neuronal skeleton and the centerline of the neuronal fiber. Furthermore, morphology metrics such as the neuronal fiber length and radius become more precise.ConclusionsThis method can improve the accuracy of a neuronal digital skeleton based on traced results. The greater the accuracy of the digital skeletons that are acquired, the more precise the neuronal morphologies that are analyzed will be.

Ultra-low-loss nanofiber Fabry-Perot cavities optimized for cavity quantum electrodynamics.

We demonstrate the fabrication of ultra-low-loss, all-fiber Fabry-Perot cavities that contain a nanofiber section, optimized for cavity quantum electrodynamics. By continuously monitoring the finesse and fiber radius during the fabrication of a nanofiber between two fiber Bragg gratings, we were able to precisely evaluate taper transmission as a function of radius. The resulting cavities have an internal round-trip loss of only 0.31% at a nanofiber waist radius of 207 nm, with a total finesse of 1380, and a maximum expected internal cooperativity of ∼1050 for a cesium atom on the nanofiber surface. Our ability to fabricate such high-finesse nanofiber cavities may open the door for the realization of high-fidelity scalable quantum networks.

Experimental determination of the interface residual stresses of carbon-fiber-reinforced polymers

Combining the matrix crack method with the geometric phase analysis (GPA) method, the interface residual stresses in carbon-fiber-reinforced polymers were measured at nanoscale. A cross-grating with a pitch of 138 nm was fabricated on the surface of composite material by electron beam lithography. The residual stresses around fibers located in the 90°, 45°, and 0° fiber layers were released through the matrix crack method using a Berkovich nanoindenter. The released residual stresses led to a change in the pitch of the grating and the corresponding residual strains were obtained by the GPA method. The Hooke’s law was employed to calculate the interfacial residual stress in the 90° fiber layers (−6.7 ± 1.3 MPa) in a range of 13.8 nm around the fiber, which agreed well with the result calculated by the Bright’s equation, and then, the interfacial residual stresses in the 45° fiber layers and residual stress along the fiber axial direction were obtained. The effect range of the radial residual stresses was equal to about one fiber radius.

CO2 capture by modified hollow fiber membrane contactor: Numerical study on membrane structure and membrane wettability

This work aims at capturing CO2 from natural gas using a verified finite element mathematical model by improving the membrane wettability, membrane structure, the type of absorbents used in the system, and the physical parameters like membrane porosity and the number of fibers used in hollow fiber membrane contactor (HFMC). The model is developed to simulate the CO2 removal using membranes by considering mass transfer equations in the presence of chemical reactions. Simulations were performed using a membrane system including 10 fibers with 175 mm length, 830 μm outer fiber radius and 450 μm inner fiber radius. The effect of adding montmorillonite nanoparticles (MMT) in weight percentages of 1%, 3%, and 5% to the PVDF membrane was perused to demonstrate the influence of membrane structure modification on system performance. The results show that the modification of membrane structure with montmorillonite nanoparticles could increase the efficiency of the system in the removal of CO2 particles by 8%. Four absorbents including MEA (monoethanol amine), PZ (piperazine), TEA (triethanolamine), and EDA (ethylenediamine) are used to identify the most effective absorbent where PZ absorbent shows the highest and EDA absorbent has the lowest carbon capture efficiency. Wettability is found to have a considerably negative impact on membrane carbon capture capacity. For instance, the modeling results show that even a 10% wetting of the membrane reduces the efficiency of the CO2 removal process by more than 47%. In addition, the results illustrate that the increase in membrane tortuosity and gas velocity have negative impacts on the separation process, while increase in the absorbent concentration, packing density and porosity enhance the separation of CO2.

The interactions of oil droplets with filter feeders: A fluid mechanics approach

Filter feeding animals capture and lose oil droplets using cilia or ramified appendages. Here we demonstrate that copepod and barnacle appendages capture fish, canola and 1-decanol oil droplets up to 11μm without selectivity for size, chemistry, density, viscosity, or interfacial tension. Following capture, the droplets are ingested or lost via detachment. Capture and detachment did not differ between a barnacle appendage and stainless-steel wires of radii Rf=50 and 250μm. Key parameters to detachment include the ratio of oil droplet radius to fiber radius, and the Weber number. Smaller oil droplet size to fiber size ratio r=Ro∕Rf, required a higher We for detachment. These data plot as a curve that predicts whether a droplet will remain captured or detach and re-enter the fluid stream, based on the fluid, the droplet radius to fiber radius ratio, and the oil droplet properties. Significantly, this curve may be used to plan responses to oil spills in marine environments.

Investigation of Meniscus Effect on Microbond Test of &lt;i&gt;Typha&lt;/i&gt; Fiber/Epoxy Matrix

The microbond test was one of the methods to examine the interfacial shear strength (IFSS) value of fiber and polymer matrix. The meniscus angle that formed at both ends of the matrix is difficult to control while manufacturing the specimen for the microbond test. Therefore, the effect of meniscus angle must be evaluated. In this paper, we evaluated the impact of variations of the meniscus angle against the maximum von-mises stress and the IFSS value of theTyphafiber epoxy matrix by finite element method. The geometry of the microbond test specimen was modeled with 0.25 mm fiber radius, 2 mm fiber length, 1.75 mm embedded length of the matrix, and varied the meniscus angles with 22°, 30°, 45°, 60°, 75°, and 90°. The mesh type quad-dominated CAX4R is used on fiber and matrix, while quad COHAX4 is applied to the cohesive element between fiber and matrix. The constantly applied displacement was adjusted to the upper end of the fiber at 0.6 mm. The simulation results showed that the difference in maximum stress obtained in each model. Furthermore, that is not given much difference in IFSS value. It can be concluded that the meniscus angle affects the maximum von-mises stress but not too much-affected IFSS value of the fiber and epoxy matrix.

Tapered Optical Fiber Detector for a Red Dye Concentration Measurement.

In this work, a detector based on optical fiber covered with Multi-Wall Carbon Nanotubes (MWCNTs) was used for sensing and removal of Alizarin from wastewaters. Alizarin is a strong anionic red dye that is part of the anthraquinone dye group. As a rule, this dye is used in the textile industry as a coloring agent. Experiments showed a good efficiency of wastewater treatment. This development could resolve the problem of water contamination with Alizarin red dye. We used a single-mode fiber SMF-28e with a core diameter of 8.2 μm and a cladding diameter of 125 μm as a base for the tapered optical fiber detector. An MWCNTs array was synthesized on the tapered optical fiber detector surface by spray pyrolysis Chemical Vapor Deposition (CVD) method at 800oC for 20 min inside a tubular furnace, using ferrocene solution in toluene as a catalyst precursor. The formed structure was applied for Alizarin detection in water. According to the patent studies, the nanotubes completely covered the optical fiber surface and the array had a high density with minimal distance between nearby nanotubes. Carbon nanotubes were oriented along the radius of the optical fiber. The average diameter of carbon nanotubes was 24 nm. The optical absorbance levels increased as the Alizarin concentration increased from 50 mg/L to 1000 mg/L. MWCNTs on the optical fiber tapered section adsorbed the dye molecules from aqueous solution. Three intensive absorption bands with the wavelength of the 700, 714 and 730 nm appeared and their intensity increased as the Alizarin concentration increased. The accumulated Alizarin can be recovered by multiple immersing clean water. This property may make tapered optical fiber detector reusable and increase the economic expediency of the sensor application. The study showed higher Alizarin adsorption efficiency of the tapered optical fiber detector compared with relative detectors. This structure can be reusable for dye detection. Removal efficiency for Alizarin reached 98.6%, which makes the tapered optical fiber detector promising for wastewater treatment and dye elimination.

Analysis on light power and three-dimentional temperature distribution characteristics of gain guided and index alternate-guided fiber lasers

Gain guided and index alternate-guided (GGIA-G) fiber was suggested by our group recently. In this work, the improved rate equations of the GGIA-G fiber laser were established and solved. The pump and signal light power distribution along the fiber longitudinal axis were simulated under the conditions of forward, backward and bidirectional pump. Furthermore, a theoretical three-dimensional temperature distribution model of the GGIA-G fiber laser was established, and the temperature distribution characteristics along both the fiber longitudinal axis and radius were simulated and compared when the fiber was pumped with different methods. The research results show that different pump method has obvious influence on both signal light power distribution and the fiber temperature. When the fiber is forward pumped, the signal light power in the fiber is the highest, and when the fiber is bidirectionally pumped, the temperature of the fiber is the lowest. The research conclusions are helpful in the application of the GGIA-G fiber.

Realization of a highly sensitive multimode interference effect-based fiber-optic temperature sensor by radiating with a Vortex beam

In this research, an ultra-high sensitive multimode interference-based fiber-optic temperature sensor is unveiled by radiating with a Vortex beam. The efficient excitation of several high-order modes within the waveguide structure has been affirmed by using the classical wave-optic model. By exploiting the advantages of Vortex beam, the difference in transmitted output power is determined for various surrounding temperatures, ranging from 28 °C–100 °C. To corroborate our theoretical study, an Eigenmode expansion solver (EME) propagation analysis has been carried out in commercially offered Mode solution software (Lumerical Inc.) to investigate the propagation characteristics of Vortex beam inside the waveguide structure. Our simulation outcome reflects a maximal temperature sensitivity of 0.14 dB/°C with a commendable sensing resolution of ∼0.07 °C. When compared to the conventional Gaussian beam-based sensor, such sensitivity of the proposed temperature sensor was found to be enhanced by a factor of about 3.5. Finally, we presented the systematic study describing the impact of fiber radius, order of Vortex beam, and waist size of input field on the sensor response. On account of such superior sensing performance, the proposed idea expedites new possibilities in any sort of physical, chemical or biological sensing needs.

Glomerular filtration and podocyte tensional homeostasis: importance of the minor type IV collagen network.

The minor type IV collagen chain, which is a significant component of the glomerular basement membrane in healthy individuals, is known to assemble into large structures (supercoils) that may contribute to the mechanical stability of the collagen network and the glomerular basement membrane as a whole. The absence of the minor chain, as in Alport syndrome, leads to glomerular capillary demise and eventually to kidney failure. An important consideration in this problem is that the glomerular capillary wall must be strong enough to withstand the filtration pressure and porous enough to permit filtration at reasonable pressures. In this work, we propose a coupled feedback loop driven by filtration demand and tensional homeostasis of the podocytes forming the outer portion the glomerular capillary wall. Briefly, the deposition of new collagen increases the stiffness of basement membrane, helping to stress shield the podocytes, but the new collagen also decreases the permeability of the basement membrane, requiring an increase in capillary transmural pressure drop to maintain filtration; the resulting increased pressure outweighs the increased glomerular basement membrane stiffness and puts a net greater stress demand on the podocytes. This idea is explored by developing a multiscale simulation of the capillary wall, in which a macroscopic (μm-scale) continuum model is connected to a set of microscopic (nm-scale) fiber network models representing the collagen network and the podocyte cytoskeleton. The model considers two cases: healthy remodeling, in which the presence of the minor chain allows the collagen volume fraction to be increased by thickening fibers, and Alport syndrome remodeling, in which the absence of the minor chain allows collagen volume fraction to be increased only by adding new fibers to the network. The permeability of the network is calculated based on previous models of flow through a fiber network, and it is updated for different fiber radii and volume fractions. The analysis shows that the minor chain allows a homeostatic balance to be achieved in terms of both filtration and cell tension. Absent the minor chain, there is a fundamental change in the relation between the two effects, and the system becomes unstable. This result suggests that mechanobiological or mechanoregulatory therapies may be possible for Alport syndrome and other minor-chain collagen diseases of the kidney.