Fiber Spacing Research Articles

Structure and properties of the acellular porcine cornea irradiated with 60Co-γ and electron beam and its histocompatibility.

Acellular porcine cornea (APC) has been used in corneal transplantation and treatment of the corneal diseases. Sterilization is a key step before the application of graft, and irradiation is one of the most commonly used methods. In this paper, APC was prepared by the physical freeze-thawing combined with biological enzymes, and the effects of the electron beam (E-beam) and cobalt 60 (60Co-γ) at the dose of 15 kGy on the physicochemical properties, structure, immunogenicity, and biocompatibility of the APC were investigated. After decellularization, the residual DNA was 20.86 ± 1.02 ng/mg, and the α-Gal clearance rate was more than 99%. Irradiation, especially the 60Co-γ, reduced the cornea's transmittance, elastic modulus, enzymatic hydrolysis rate, swelling ratio, and cross-linking degree. Meanwhile, the diameter and spacing of the collagen fibers increased. In the rat subcutaneous implantation, many inflammatory cells appeared in the unirradiated APC, while the irradiated had good histocompatibility, but the degradation was faster. The lamellar keratoplasty in rabbits indicated that compared to the E-beam, the 60Co-γ damaged the chemical bond of collagen to a larger extent, reduced the content of GAGs, and prolonged the complete epithelization of the grafts. The corneal edema was more serious within 1 month after the surgery. After 2 months, the thickness of the APC with the two irradiation methods tended to be stable, but that in the 60Co-γ group became thinner. The pathological results showed that the collagen structure was looser and the pores were larger, indicating the 60Co-γ had a more extensive effect on the APC than the E-beam at 15 kGy.

Kenevir lifli sandviç panellerin 3 nokta eğilme davranışları

The article discusses the increasing interest in natural fibers as a substitute for synthetic fibers in the development of composites due to the depletion of crude oil reserves, environmental concerns and regulations targeting the reduction of carbon emissions. The mechanical properties of natural fibers are closely linked to their chemical composition and structure, which can be influenced by various factors such as harvesting time, growth conditions, storage practices, extraction techniques and pre fabrication chemical treatments. The article also explains the finite element analysis steps for a sandwich structure created using hemp fibers with a 3 mm diameter and 20 mm spacing between two carbon prepreg layers for a 3-point bending test.Finally, numerical analysis outputs of sandwich structures created with hemp fibers at intervals of 10 mm, 20 mm, and 30 mm, and diameters of 2 mm, 3 mm, and 4 mm, are presented graphically to demonstrate the effects of changes in hemp fiber spacing and diameter on stress.

Waterdrop-assisted efficient fog collection on micro-fiber grids

Fog collectors can mitigate water scarcity by capturing droplets from fog streams. Previous research focuses on improving aerodynamic design and surface characteristics to enhance collection efficiency. However, limited attention has been given to micro-meter level fog-intercepting structures and the impact of waterdrop clogging. This study investigates the fog collection process on microfiber grids with varying fiber spacings and diameters. Waterdrops clog the grid openings with a pattern that small waterdrops satelliting large ones. Due to the small fiber diameter, the waterdrops are “visible” to incoming airflow and strongly affect fog droplet interception. The large waterdrops deflect incoming fog flow towards the small ones, and the small waterdrops efficiently capture the fog droplets. Consequently, the fog collectors based on microfiber grids demonstrated an exceptional water collection efficiency of up to 21.4%. The micro-fiber grids require minimal material usage and no special surface treatment, highlighting a great potential in fog water collection. Additionally, this work provides a novel design strategy of fog collector, i.e., reducing the size of the fog-intercepting structure to directly capture fog droplets by waterdrops.

Fibre alignment in fresh concrete with coarse aggregates and its visualization in transparent model concrete

Steel fibres distributed in concrete can greatly improve the mechanical performance of concrete, especially flexural and tensile behavior, if their orientations align to the direction of principal tensile stress. The study attempts to find diversified characters of fibre alignment in fresh concrete with consideration of adding coarse aggregates. A transparent concrete model, consisting of Carbopol gel, glass beads and crystals, is designed for the observation of fibre orientation. It shows good transparency and visibility, and can consider the effect of coarse aggregates since the volume fraction and particle size distribution of crystals are the same as coarse aggregates in real concrete mixture. The rheological properties of the model can be adjusted by the dosage of Carbopol and glass beads. Using this concrete model, the distribution and orientation of fibres can be directly observed and analyzed, considering the effect of aggregate sizes, concrete rheology and vibration time. The results show that coarse aggregates could limit the distribution space of fibres and lead to the decrease of fibre orientation coefficient. Fibre dispersion coefficient also decreases with the increase of aggregate sizes.

Manufacturing multifunctional vascularized composites by through-thickness frontal polymerization and depolymerization: A numerical study on the impact of sacrificial fiber configurations

Concurrent through-thickness frontal polymerization and vascularization (FP-VaSC) is emerging as a promising alternative to conventional multi-step fabrication approaches for vascularized thermoset polymers and composites. This method relies on a localized and self-propagating exothermic polymerization reaction front of the polymer matrix, to simultaneously cure the matrix, and depolymerize pre-embedded sacrificial templates. It delivers fully cured thermoset polymers and composites rapidly and energy-efficiently with the desired vascular system in a single step. While previous studies demonstrated the capability of this method for making woven laminates with a single vascular channel created by embedding a single straight sacrificial fiber, it is desirable to explore the potential of this method for making composites with multiple channels for more practical applications. We employ a previously validated thermo-chemical model from our prior study, to systematically investigate the reaction process with the presence of multiple sacrificial fibers. Two sacrificial fiber configurations are considered, namely, inline and staggered fiber configurations. Within each configuration, we consider a range of horizontal and vertical fiber spacing, which also lead to different sacrificial fiber volume fractions. This study reveals the interactions between the sacrificial fiber and the reactions, identifies the working window of this method for different sacrificial fiber configurations, and provides guidance for manufacturing laminates with multiple vascular channels. We also propose an analytical model that can quickly approximate the maximum sacrificial fiber volume fraction that can lead to successful FP-VaSC for a given carbon fiber volume fraction and compare the results with those from the thermo-chemical modeling.

Radon-Nikodýmification of arbitrary measure spaces

We study measurable spaces equipped with a σ-ideal of negligible sets. We find conditions under which they admit a localizable locally determined version – a kind of fiber space that locally describes their directions – defined by a universal property in an appropriate category that we introduce. These methods allow to promote each measure space (X, A , µ) to a strictly localizable version (X̂, Â, µ̂), so that the dual of L1 (X, A , µ) is L∞ (X̂, Â, µ̂). Corresponding to this duality is a generalized Radon-Nikodým theorem. We also provide a characterization of the strictly localizable version in special cases that include integral geometric measures, when the negligibles are the purely unrectifiable sets in a given dimension.

Effect of curing temperature on shape memory properties of graphene oxide‐carbon fiber hybrid‐reinforced shape memory polymer composites

AbstractIn order to study the effect of curing temperature on the shape memory properties (SMPs) of GO‐CF hybrid‐reinforced SMPCs, eight sets of composites were prepared at different curing temperatures (60, 70, 80, 90, 100, 110, 120, and 130°C). The rheological and curing properties of the matrix, and the apparent density, porosity, microstructure, and SMPs of the composite were measured and analyzed, respectively. The results showed that at 100°C, the composite has the highest apparent density (1.52 g/cm3), the lowest porosity (0.47%), the best SMPs, the shape fixed rate of 99.13%, the shape recovery rate of 96.54%, and the maximum shape recovery force (5.15 N). The shape recovery speed and rate of shape recovery are also the fastest. This is because when the curing temperature is 100°C, the viscosity of the matrix can be kept at a low level, and the curing reaction rate is appropriate. This not only ensures that the matrix can be fully infiltrated into the fiber space but also obtains the matrix with appropriate crosslinking degree. Therefore, the microstructure of the prepared composite is ideal, which makes the matrix has a strong ability to restrain the expansion force of the fiber and a high efficiency of the transfer force and heat. Finally, in the test of SMPs, the composite showed higher SMPs. It was concluded that the SMPs of the composites were mainly affected by the infiltration effect of the matrix in the fiber.Highlights The microstructure of the composite was more ideal at 100 °C. The composite with the lowest porosity has the best shape memory properties. The high porosity weakens the heat and force transfer ability of the matrix. The shape memory properties of composites are the best prepared at 100 °C.

Distribution patterns of reactive species in the interaction between atmospheric pressure plasma jet and fiber membrane

Surface modification of polymer fiber membranes using atmospheric pressure low-temperature plasma has gained significant attention in recent years. The effectiveness of surface modification determined by the uniform distribution of reactive species when plasma touching the fibers. In this study, we investigated the distribution patterns of plasma reactive species on the fibers surface with different fiber spacings by both experiment and modeling. The results revealed that reduced fiber spacing produced an obstructive effect on the propagation of reactive species. This obstruction was primarily caused by the accumulation of a significant charge on the windward side of the fiber. Consequently, there was a substantial difference in the fluxes of reactive species between the windward and leeward sides of the fiber membrane, resulting in poor uniformity of the reactive species distribution. It was worth noting that the fluxes of reactive species exhibited a double-peak distribution on the circumferential surface of the fiber filaments. This phenomenon was attributed to the coupling effect between the fiber filaments, wherein the electric field strength was higher within the gap. High electric field strength facilitated the generation and propagation of reactive species. However, as the fiber spacing decreased, the propagation of high field strength became limited until it merged into the fiber gap.

Neuroprotective effect of 1,25‑dihydroxyvitamin D3 against hyperoxia‑induced brain injury in premature rats.

Studies have shown that vitamin D plays a crucial role in brain development, brain metabolism and neuroprotection. There is little evidence for the neuroprotective effect of 1, 25‑dihydroxyvitamin D3 (1,25‑(OH)2D3) on various brain injury models. The aim of this study was to investigate the neuroprotection effect of 1,25‑(OH)2D3 against hyperoxia‑induced brain injury in premature rats. Sprague‑Dawley rats were exposed to 95% oxygen or room air for 24 h and treated with 1,25‑(OH)2D3 or normal saline for 14 consecutive days. The histopathological changes of optic chiasma tissue were observed by hematoxylin‑eosin staining. Immunohistochemistry, qRT‑PCR, and western blot were performed to detect the expression of integrin‑β1 and yes‑associated protein (YAP) in the organization of the optic chiasm. Histopathological sections of optic chiasma showed visible optic nerve swelling, expanded nerve fiber space, uneven staining, obvious oligodendrocyte proliferation and disordered cell arrangement accompanied by inflammatory cell infiltration and exudation after 7 days and 14 days of hyperoxia exposure. The hyperoxia group treated with 1,25‑(OH)2D3 were showed improvement of brain injury with reduced inflammatory exudation, uniform nerve fiber staining and less obvious oligodendrocyte proliferation. Immunohistochemical staining, qRT‑PCR and western blot indicated that 1,25‑(OH)2D3 treatment upregulated the expression of integrin‑β1 and YAP in the hyperoxia group on day 7. However, the expression of YAP was significantly increased compared with control group and treatment with 1,25‑(OH)2D3 reduced the expression of YAP in the hyperoxic group on day 14. 1,25‑(OH)2D3 may regulate the expression of integrin‑β1 and YAP to alleviate hyperoxia‑induced brain injury in premature rats.

Correlation between Convolution Kernel Function and Error Function of Bone Fractal Operators

This article studies the convolutional kernel function of fractal operators in bone fibers. On the basis of the micro-nano composite structure of compact bone, we abstracted the physical fractal space of bone fibers and derived the fractal operators. The article aims to construct the convolutional analytical expression of bone fractal operators and proves that the error function is the core component of the convolution kernel function in the fractal operators. In other words, bone mechanics is the fractional mechanics controlled by error function.

Equivariant pliability of the projective space

We classify finite subgroups Gsubset {textrm{PGL}}_4({mathbb {C}}) such that {mathbb {P}}^3 is not G-birational to conic bundles and del Pezzo fibrations, and explicitly describe all G-Mori fibre spaces that are G-birational to {mathbb {P}}^3 for these subgroups.

Assessment and ANN model development of natural light transmittance of light-transmitting concrete

This study aims to reveal the potential of Light-transmitting concrete (LTC) in transmitting natural light or sunlight, and to investigate the relationship between fibre diameter, fibre spacing, solar incidence angle, surface area, and light transmittance properties. The artificial neural network model as well as explicit equations from the model were developed to predict the light transmittance of LTC. The surface area was altered by varying LTC block arrangements from one to six. It was found that light incidence angle significantly affected the light transmittance of LTC. The highest light transmittance of LTC was achieved near solar noon, but it decreased drastically as soon as the solar incidence angle exceeded the acceptance angle. The effect of the LTC surface area and solar incidence angle on light transmittance diminished with a smaller fibre diameter or larger fibre spacing. The ANN model and explicit equations developed from the network provide good accuracy in predicting light transmittance of LTC.

Kodaira Dimension of Fibrations Over Abelian Varieties

Abstract We prove an additivity result for the log Kodaira dimension of algebraic fiber spaces over abelian varieties, a superadditivity result for fiber spaces over varieties of maximal Albanese dimension, as well as a subadditivity result for log pairs.

Morphology of Particulate Structures on a Fiber Array before and at Clogging Point of an Aerosol Filtration Process

Fundamental microscopic investigations are based on the interaction between filter fiber and particles. The fibrous filter theory is based on a single fiber of a fiber array, and experiments focus either on a single fiber or a fiber array. This study investigates the particle loading process of a fiber array and focuses on the microscopic development of particle structures on the fiber array. Gravimetric measurements and image analysis of the array were used to study the development of the particle structure and morphology. Microscopic analysis of the video data focused on the evolution of particle accumulation within the fiber spacing, the development of boundary lines of the particle structure, and the number/size of bridges and pores within the particle structure. For the tested flow velocities, an increase in mass was observed to increase the duration of the filtration process. An extreme increase in deposited mass was observed at the moment of complete blocking (clogging) of the fiber spacing at flow velocities of 0.65 m/s. The size of pores (hydraulic diameter) increased with the flow velocity during the loading procedure. However, the total number of pores was higher in tests with lower Stokes numbers due to the dendritic and more porous structure. This work provides insights into the growth kinetics and structural setup of the particle structure (on a microscopic level). This will improve the understanding of the change of the filtration process from the transition phase to the clogging phase in fibrous filters.

Proposed shear capacity equation for ultra-high performance fiber reinforced concrete beam containing coarse aggregate

This paper proposes a shear capacity equation for ultra-high performance fiber reinforced concrete beam containing coarse aggregate (UHPFRC-CA) and without coarse aggregate (UHPFRC) that captures all UHPFRC’s direct and indirect shear influencing factors. Six beam samples (each sample containing two beam specimens) were tested for shear strength under four point loading configuration using shear span-depth ratio (a/d), percentage volume of steel fiber (Vf), shape of steel fiber and stirrup spacing (s) as shear design parameters to obtain their ultimate shear strength (Vu). The obtained Vu was subjected to Analysis of Variance (ANOVA) to assess the significance of adding a coarse aggregate factor (dca) to the proposed equation. The proposed equation was validated by comparing its Vu with this study’s experimental Vu, other researchers’ Vu and Vu estimated using existing shear equations. ANOVA results showed that dca is significant in the Vu of UHPFRC-CA beams. Findings also revealed that the proposed equation does not only predict the Vu of UHPFRC-CA beams with a very high degree of accuracy but also gives better estimates of the Vu of UHPFRC-CA and UHPFRC beams when compared with the existing shear equations considered in this study. Further findings showed that the proposed equation reflects the effect of changes in Vf, a/d, s, ρ, shape of steel fiber and maximum size of coarse aggregate better than the existing shear equations for UHPFRC beams. Therefore, the proposed equation can be safely use for the shear design of UHPFRC-CA beam whose compressive strength ranges from 150 N/mm2 to 170 N/mm2.

Natural light transmittance of light-transmitting concrete (LTC) incorporated with optical fibres

This paper focused on investigating the light transmittance properties of light-transmitting concrete (LTC) under sunlight. Self-compacting concrete (SCC) and polymethylmethacrylate (PMMA) optical fibres with fibre diameter of 2 mm were used to fabricate LTC blocks. Since fibre spacing, LTC surface area, and light incidence angle are important factors which affect the light transmittance, but are rarely investigated in previous studies, the current study used fibre spacing of 15 mm, 18.75 mm, and 25 mm, and different LTC surface area, altered by placing one to six blocks together, to investigate the effects on light transmittance of LTC under sunlight. The light transmittance tests were conducted on a sunny day from 9 a.m. to 4p.m. A light meter was used to measure the intensity of light transmitted by the LTC. Fresh properties tests of SCC and compression tests on LTC were also conducted. The results show that LTC incorporated optical fibres had lower compressive strength compared to the control concrete block. The difference in fibre spacing has no significant effect on the compressive strength of LTC. The light transmittance of LTC with a spacing of 15 mm has the best light transmittance performance among the LTC blocks with different fibre spacing. The increment of light transmittance was approximately 24% to 28% near solar noon, when the LTC surface area increased from one block to six blocks regardless of the fibre spacing. It was found that the light transmittance declined drastically when the light incidence angle was beyond the acceptance angle. Further research is needed on LTC that takes into account the distance between the light meter and the LTC block to obtain a more comprehensive understanding of light transmittance before it is applied in building construction, with the aim to reduce light energy consumption.

Study on mechanical properties of multi-fiber reinforced fly ash concrete

Aiming at the problems of low strength and easy cracking of concrete with large dosages of fly ash, SSF, ARF, and PPF were mixed into concrete respectively according to the same volume ratio. Various indexes were tested and the change rule was analyzed. Besides, the fiber spacing theory was adopted to explore the anti-cracking mechanism of fiber on concrete. The results indicate that the compressive strength and flexural strength of concrete were improved by three kinds of fiber in different dosage; the RFC of 7d was between 14% and 18%, and that of 28d was between 13% and 20%; SSF in concrete would produce strong bonding force and mechanical bite force. ARF has a small impact on the compressive strength of concrete, but a significant impact on the flexural strength of concrete. PPF can be more evenly dispersed in concrete to disperse and release a certain amount of stress and play a reinforcing role. Combined with SEM Microscopic Morphology Analysis of Concrete, a concrete mix ratio of three fibers 1:1:1 is recommended.

Stochastic buckling response of variable fiber spacing composite plate under thermal environment

The effectiveness of variable fiber spacing composite (VFSC) laminates subjected to thermal loading is compared with uniformly distributed fiber composite (UDFC) laminates. The higher-order shear deformation theory (HSDT) is adopted to develop a FE model for estimating critical thermal buckling load. Three types of fiber distribution patterns are considered to study the effect of the non-uniform spacing distribution of fiber on thermal buckling, and the results are compared with UDFC. Further, a surrogate model based on the radial basis function network (RBFN) is developed to examine the impact of composite properties uncertainty on the critical buckling response of UDFC and VFSC laminates under thermal loading. The RBFN model is found to be highly efficient and possesses a close match with Monte Carlo simulation (MCS). Though the VFSC laminates possess a large deviation (standard deviation) in the buckling temperature, the stochastic effect (standard deviation/mean) shows relatively minimal variation in VFSC and UDFC laminates. The effect of each composite property is investigated for different lamination sequences and boundary conditions. From the sensitivity analysis, the thermal expansion coefficient of matrix [Formula: see text] is found to be the most sensitive property for all the investigated cases. Lastly, the RBFN model is utilized to quantify reliability parameters for multiple stochasticity levels.

Pullout damage analysis of steel fibers under dynamic load based on numerical simulation

FRC is constantly subjected to dynamic loads during its service period, and dynamic pullout behavior of the fibers and the coupling effect between fibers can significantly affect the crack initiation and propagation of FRC. In this paper, based on the single fiber pullout behavior of experimental and numerical results, the failure process of the twin fibers dynamic pullout test was simulated by RFPA3D program with discontinuous and heterogeneous characteristics. The influence of fiber embedding length and fiber spacing on the interfacial bond behavior were analyzed in details. The internal damage degree, crack propagation, and interfacial shear stress of all test series were quantitatively characterized. The results indicate that the specimens with various fiber embedding lengths and fiber spacings present distinct damage evolution patterns. The decrease of the peak of AE events is followed by an increase, when the fiber embedding length is increased. In addition, the fiber spacing has a large influence on the distribution and transmission of interfacial shear stress. With the increase of fiber spacing, the peak of interfacial outside shear stress increases, while the peak value of interfacial inside shear stress gradually decreases. Meanwhile, the AE-accumulative energy presents a trend of decreasing first and then increasing.

Communication With Unreliable Entanglement Assistance

Entanglement resources can increase transmission rates substantially. Unfortunately, entanglement is a fragile resource that is quickly degraded by decoherence effects. In order to generate entanglement for optical communication, the transmitter and the receiver first prepare entangled spin-photon pairs locally, and then the photon at the transmitter is sent to the receiver through an optical fiber or free space. Without feedback, the transmitter does not know whether the entangled photon has reached the receiver. The present work introduces a new model of unreliable entanglement assistance, whereby the communication system operates whether entanglement assistance is present or not. While the sender is ignorant, the receiver knows whether the entanglement generation was successful. In the case of a failure, the receiver decodes less information. In this manner, the effective transmission rate is adapted according to the assistance status. Regularized formulas are derived for the classical and quantum capacity regions with unreliable entanglement assistance, characterizing the tradeoff between the unassisted rate and the excess rate that can be obtained from entanglement assistance. It is further established that time division between entanglement-assisted and unassisted coding strategies is optimal for the noiseless qubit channel, but can be strictly suboptimal for a noisy channel.