Neighboring Fibers Research Articles

Pea-like inspired design: Lignin nanospheres-mediated PVA film with high strength, low water evaporation permeability, strong UV resistance and anti-oxidation properties for extending food freshness

The excessive utilization of petroleum-based plastic products has inflicted significant harm upon the ecological and health problems, compelling individuals to continually seek renewable and biodegradable polymer materials as alternatives. Drawing inspiration from the structure of a natural pea pod, a unique interlocking packaging material based on a pea-like structure is obtained via green electrospinning and mild glutaraldehyde (GA) cross-linking method. Herein, polyvinyl alcohol (PVA) serves as a green protective layer encompassing the active lignin nanospheres (LNP) pod, forming a packaging film that prevents LNP migration. The LNP within the fibers can effectively shorten the fiber spacing, and when exposed to the GA vapor, they promote the bonding between neighboring fibers to form a tight interlock structure. Benefiting from the interlocking pea-like structure, the film exhibits excellent tensile strength (3.53 ± 0.02 MPa), wetting strength (1.92 ± 0.05 MPa), and outstanding water vapor barrier properties (3.27 ± 0.3 10−10 gm−1 s−1 Pa−1). Furthermore, the inclusion of LNP endows exceptional water resistance, UV-blocking capabilities, antibacterial and antioxidant properties, which can effectively prolong the storage life of perishable fruits. This eco-logical sustainable design holds tremendous potential in mitigating the burden on the environment, thus making a novel avenue for exploring alternatives to petroleum-derived plastics.

Fiber Flexibility Reconciles Matrix Recruitment and the Fiber Modulus to Promote Cell Mechanosensing.

The mechanical interaction between cells and the extracellular matrix is pervasive in biological systems. On fibrous substrates, cells possess the ability to recruit neighboring fibers, thereby augmenting their own adhesion and facilitating the generation of mechanical cues. However, the matrices with high moduli impede fiber recruitment, restricting the cell mechanoresponse. Herein, by harnessing the inherent swelling properties of gelatin, the flexible gelatin methacryloyl network empowers cells to recruit fibers spanning a broad spectrum of physiological moduli during adhesion. The high flexibility concurrently facilitates the optimization of fiber distribution, deformability, and modulus, contributing to the promotion of cell mechanosensing. Consequently, the randomly distributed flexible fibers with high moduli maximize the cell adhesive forces. This study uncovers the impact of fiber recruitment on cell mechanosensing and introduces fiber flexibility as a previously unexplored property, offering an innovative perspective for the design and development of novel biomaterials.

Influence of nearby fiber on fiber–matrix debonding: Coupled Criterion prediction and debonding shape determination

Fiber–matrix interface debonding in two-fiber specimens under remote tensile loading is studied both experimentally and numerically by means of a coupled stress and energy criterion. Depending on its relative position, the neighboring fiber induces a perturbation of both stress and energy fields at the reference fiber interface which results in asymmetrical debonding initiation and propagation. The determination of the debonding initiation and propagation shape is addressed based on either (i) stress isocontours, (ii) energy isocontours or (iii) the Coupled Criterion (CC). It was found that the debonding initiation configuration can be determined based on stress (respectively energy) isocontours for small (respectively large) enough interface brittleness number. For intermediate brittleness number, the debonding initiation configuration cannot be obtained using neither the stress nor the energy isocontours, but requires a coupling of both aspects. Despite different initiation debonding configurations, the corresponding initiation remote stresses do not differ much, which results in similar debonding configurations after unstable crack propagation following initiation.

Inter-Core Crosstalk-Aware Backup Network Design Model against Probabilistic Link Failures in Multi-Core Fiber Optical Path Network

Multi-core fiber (MCF) is one of the promising space-division multiplexing technologies to increase the capacity of optical networks. MCF-based networks have two challenges. One is the inter-core crosstalk (XT) that degrades the quality of optical signals in two neighboring fiber cores. The other is network protection against link failures that cause massive data loss. One way to protect against multiple link failures is to prepare physically separated links as a backup network. Probabilistic protection improves the efficiency of protection by allowing a certain probability of protection failure. Existing studies on backup network design with probabilistic protection do not target MCF-based networks, which raises problems such as protection failure due to the inter-core XT and excessive consumption of optical resources. To address these problems, this paper proposes a XT-aware backup network design model for the MCF optical path networks. The proposed model protects the network against probabilistic multiple link failures. We adopt probabilistic protection that allows a certain probability of protection failure due to the inter-core XT and minimizes the required number of links in the backup network. We present an algorithm to satisfy the probabilistic protection requirement and formulate the model as an integer linear programming problem. We develop a heuristic approach to apply the proposed model to larger networks. Numerical results observe that the proposed model requires fewer links than the dedicated allocation model, which provisions the backup paths in the same manner as the primary paths.

OPTIMAL LOCATION OF ACTION POTENTIAL GENERATION BASED ON ACTIVATION FUNCTION USING COMPUTATIONAL MODELLING

Transcutaneous electrical nerve stimulation is used to elevate health-related disorders. This technology is now an important therapeutic system for medical science. In this system, the electrical current pulse is applied over the skin through the inner layers via electrodes to activate excitable tissue layers. Activating other excitable tissue layers may cause discomfort. Thus, it is vital to design electrode configuration arrangements to activate the target anatomical layers without affecting the neighboring ones. A device for primary headaches showed mixed results. This may be related to the electrode position that requires higher stimulus current levels to activate target nerve fibers. This may stimulate neighboring nerve fibers which resulted in the discomfort of patients. A feasible solution is to identify the optimal electrode configuration based on the activation function which is the second derivative of the electric potential along an axon. This may guide to estimate of the possibility of action potential generation on the neural tissue layer using a specified electrode arrangement. In this study, the multilayered human head was developed based on MRI data set using pre and post-processing. Then multi-electrode arrangements were developed to examine the possible nerve activation location. Results showed that the nerve fibers were activated at the same location of the trajectory for the anodal and cathodal stimulation. This may be proof that the activation function can be used to define the optimal location of nerve activation. This may lead to lower thresholds for similar therapeutic benefits in transcutaneous electrical nerve stimulation with decreased power consumption.

Stochastic model for predicting the shape of flexible fibers in suspensions

The shape of flexible fibers in a suspension varies depending on the hydrodynamic interaction of each fiber with the flow and with the neighboring fibers. By examining the total fiber forces from direct numerical simulations, this study proposes a reduced-order stochastic model that predicts the three-dimensional shape of fibers settling inertially in a suspension of different concentrations. While at low concentrations gravity is the main contributor to the planar deformation of the fibers, at higher concentrations, the interaction of fibers with each other creates large out of plane deformations.

Far field energy distribution control using a coherent beam combining femtosecond digital laser.

We report on far field energy distribution control using a coherent beam combining femtosecond digital laser employing 61 tiled channels. Each channel is considered as an individual pixel where amplitude and phase are controlled independently. Applying a phase difference between neighboring fibers or neighboring fiber-lines gives high agility for far field energy distribution and paves the way for deeper exploration of phase patterns as a tool to further improve tiled-aperture CBC laser efficiency and far field shaping on demand.

Ultrafast deposition of polydopamine for high-performance fiber-reinforced high-temperature ceramic composites

The low deposition time efficiency and small thickness limit the expansion of polydopamine (PDA) application to fiber-reinforced high-temperature ceramic composites. In this work, the electric field-assisted polymerization (EFAP) route was developed to improve the deposition time efficiency of PDA coating and overcome the thickness limitation. Carbonized polydopamine (C-PDA) coating was used as the interphase of carbon fiber-reinforced ZrB2-based composites (Cf/ZrB2-based composite) to bond rigid fibers and brittle ceramics, where C-PDA coating was prepared by the carbonization of PDA coating. Firstly, uniform and dense PDA coatings were deposited on carbon fibers (Cf) by EFAP. The thickness of PDA coating reached the micron level (over 1800 nm) for the first time. Benefiting from the EFAP route promoting the oxidation process of dopamine (DA) and accelerating the aggregation and in-situ polymerization of DA and its derivatives on the surface of Cf, the deposition rate of PDA coating reached 5589 nm/h, which was 3 orders of magnitude higher than that of the traditional self-polymerization process. By adjusting the EFAP parameters (e.g. DA-concentration, current, and deposition time), the thickness of PDA coating could be conveniently designed from nano-scale to micro-scale. Then, PDA coating was pyrolyzed to obtain C-PDA coating. C-PDA coating was well bonded on Cf without visible cross-sticking among neighboring fibers. C-PDA coating presented a layered structure and the thickness of C-PDA coating could be designed by controlling the thickness of PDA. C-PDA coating was used as the interfacial phase of the Cf/ZrB2-based composite, which ensured that the composite possessed good load-bearing capacity and thermal stability. Moreover, extraordinary damage resistance of the composite was achieved, with work of fracture up to 9936 ± 548 J/m2 at room temperature and 19,082 ± 3458 J/m2 at 1800 °C. The current work provides a high time efficiency processing route for depositing PDA coating on carbon fibers and demonstrates the attractive potential of PDA coating in fiber-reinforced high-temperature ceramic composites.

Opportunities of microsurgical training using a stereomicroscope and simple instruments

Background. Modern neurosurgery requires the surgeon to be skilled in microsurgical techniques to be able to operate efficiency and safety. Maintaining and developing these skills is one of main goal for neurosurgery. Optimal use of simple models for microsurgical techniques. For this purpose, we use an stereomicroscope and simple microinstruments to enable training without interruption from the main activity or at home.Aim. To introduce a microneurosurgery training based on use of stereomicroscope and simple microinstruments that can be used for daily training.Materials and methods. Simple microinstruments and stereomicroscope were used for anastomosis and suturing training. All equipment and tools were purchased on the AliExpress online trading platform. We suture neighboring fibers of the gauze with 9/0-12/0 nylon under fixed and highest magnification. Chicken blood vessels were used as a material for anastomosis training. A long segment of blood vessel from the proximal brachial artery to the distal radial artery was used for anastomosis. End-to-side anastomosis was practiced first, and the training continued with end-to-end anastomosis of the appropriate segments. Also, we used homemade box made of LEGO for training dexterity and maneuverability in the limited and deep field. Progress in changing microsurgical skills was assessed by the duration and quality of suturing and anastomoses.Results. The instruments used for these models were affordable, simple and easy to use. The simple, but the same time effective training, is the suture neighboring fibers of the gauze. Daily training allowed us improve the skills of anastomosis reducing time for anastomosis end-to-side from 40 min to 22 min 40 sec. The same results we noticed using suture neighboring fibers of the gauze, reducing time of exercises by 15 min. This training system is somewhat of a drawback compared to the simulation of a real clinical setting. However, due to the extremely easy accessibility and accessibility, the stereomicroscope and simple instrument allow us to use them for daily training. This resulted in a steep learning curve of the technique.Conclusion. This study suggests an effective and feasible method for microneurosurgical training using stereomicroscope and simple microinstruments. The improvement of our manual skills, marked by constant training, testifies about the necessity of microsurgical training both in the training of neurosurgeons and in the future.

Modelling neuron fiber interaction and coupling in non-myelinated bundled fiber

Understanding the local dynamics of a neural network relies heavily on local field potential and cell-field interaction. But it is still unclear how local the local potential is and what kinds of consequences the trans-membrane current flow and produced electric field have on the local neural fiber. Mimicking signal transmission in neighboring nerve fiber, a simulation model is built to analyze local behavior due to trans-membrane current, cell-field interactions, and their repercussions on the bundled fiber system. Simulation studies reveal that depending on the coupling parameters, activity in one fiber can depolarize or hyper-polarize adjacent fibers. The suggested cell-field interaction model was tested using an orientation-selective coupled retinal ganglion cell network, which was compared to its uncoupled counterpart. The proposed work has been used to model and simulate local signal dynamics in a bundled fiber system of an orientation-selective RGC network due to cell-field interaction, as well as to gain insight into the possible significance of dendritic fiber coupling in orientation selectivity bandwidth adjustment.

Driving an Oxidative Phenotype Protects Myh4 Null Mice From Myofiber Loss During Postnatal Growth.

Postnatal muscle growth is accompanied by increases in fast fiber type compositions and hypertrophy, raising the possibility that a slow to fast transition may be partially requisite for increases in muscle mass. To test this hypothesis, we ablated the Myh4 gene, and thus myosin heavy chain IIB protein and corresponding fibers in mice, and examined its consequences on postnatal muscle growth. Wild-type and Myh4–/– mice had the same number of muscle fibers at 2 weeks postnatal. However, the gastrocnemius muscle lost up to 50% of its fibers between 2 and 4 weeks of age, though stabilizing thereafter. To compensate for the lack of functional IIB fibers, type I, IIA, and IIX(D) fibers increased in prevalence and size. To address whether slowing the slow-to-fast fiber transition process would rescue fiber loss in Myh4–/– mice, we stimulated the oxidative program in muscle of Myh4–/– mice either by overexpression of PGC-1α, a well-established model for fast-to-slow fiber transition, or by feeding mice AICAR, a potent AMP kinase agonist. Forcing an oxidative metabolism in muscle only partially protected the gastrocnemius muscle from loss of fibers in Myh4–/– mice. To explore whether traditional means of stimulating muscle hypertrophy could overcome the muscling deficits in postnatal Myh4–/– mice, myostatin null mice were bred with Myh4–/– mice, or Myh4–/– mice were fed the growth promotant clenbuterol. Interestingly, both genetic and pharmacological stimulations had little impact on mice lacking a functional Myh4 gene suggesting that the existing muscle fibers have maximized its capacity to enlarge to compensate for the lack of its neighboring IIB fibers. Curiously, however, cell signaling events responsible for IIB fiber formation remained intact in the tissue. These findings further show disrupting the slow-to-fast transition of muscle fibers compromises muscle growth postnatally and suggest that type IIB myosin heavy chain expression and its corresponding fiber type may be necessary for fiber maintenance, transition and hypertrophy in mice. The fact that forcing muscle metabolism toward a more oxidative phenotype can partially compensates for the lack of an intact Myh4 gene provides new avenues for attenuating the loss of fast-twitch fibers in aged or diseased muscles.

Determination of the influence of rock and grinding modes on the surface roughness of wood

Experimental studies of the influence of wood species and grinding modes on the roughness of the obtained surface were carried out. It is investigated that the type of wood also affects the magnitude of the irregularities of the surface to be treated, namely the magnitude of the roughness of the treated surface is inversely proportional to the density of the treated material. Regression models are obtained, which characterize the roughness of the surface of oak and spruce wood depending on the cutting speed and the specific pressure of pressing. It is established that the cutting speed has a positive effect on the roughness of the treated surface. This is due to the fact that at high cutting speeds wood fibers (especially relevant for hardwoods with higher density) show proper support to the cutter and do not have time to break under its pressure, and cut with a cutter before it breaks their connection with neighboring fibers. Therefore, the purity of the treated surface will be better. It is established that with the increase of cutting speed from 10 to 30 m / s by grinding skin of oak wood surface roughness decreases by 40-60%, and spruce - by 44-86%. Spruce has a 10-20% roughness dynamics than oak. It was found that with the increase of the specific pressure of pressing the part to the sanding skin on the surface of oak wood, the surface roughness increases by 20-30%, and the surface of spruce wood - by 12-32%. In spruce, the deterioration of roughness is 12-13% greater than in oak. It is established that with the increase of the feed rate on the surface of oak wood the surface roughness increases by 21-30%, in spruce - by 13.63-23.46%. In spruce deterioration of roughness by 9-13% more than in oak. To carry out effective grinding to obtain a quality surface (such as oak and spruce), the following input values are recommended: cutting speed 20-30 m / s; feed speed 6-8 m / min; specific clamping force 2.2-4.4 kPa; grain size of skins: P180-P150; P120-P100; P90-P60.

Full sensitivity-driven gap/overlap free design of carbon fiber-reinforced composites for 3D printing

This paper presents a mathematically stringent method for gap/overlap free design of carbon fiber-reinforced composites for 3D printing. The proposed method employs signed distance level set function to represent the fiber paths by extracting the equidistant iso-level set profiles, through which neighboring fiber paths keep a constant distance, eliminating the gap and overlap defects of existing methods that generate fiber paths from discretely defined fiber angle variables. Then, a compliance minimization fiber path optimization problem is formulated under the level set framework for optimal fiber-reinforcement design. A major contribution lies in the solution of the optimization problem. The adjoint sensitivity analysis is performed to derive the gradient information for fiber path design update. More importantly, the domain integral term inside the sensitivity result is transformed into a boundary integral expression facilitated by extraction of the structural skeletons and rays. Hence, the full sensitivity result is derived instead of eliminating the non-executable domain integral terms in existing studies, which results in even faster and more stable convergence. A few numerical examples are studied to demonstrate the effectiveness of the proposed fiber path optimization method. 3D printing and mechanical testing results validate the optimized fiber-reinforcement effect, as well as the manufacturability improvement by avoiding gap and overlap defects.

High-Performance All-Bio-Based Laminates Derived from Delignified Wood

The need for renewable bio-based materials that could replace well-established synthetic composite materials is rapidly growing. For example, bio-based materials are increasingly used in applications where a lightweight design should be combined with sustainability and recyclability. However, it is often very challenging to directly transfer the excellent properties of biological materials to a product in a scalable and cost-efficient manner. In this study, we combined delignified wood layers (veneers) and a starch-based glue into bio-based high-performance composites. First, we investigated the ideal amount of starch-based glue between the layers to prevent delamination in the final composite. Then, we produced laminates in unidirectional, cross-ply, and quasi-isotropic configurations using wet processing. Laminates with tensile properties up to 40 GPa and 200 MPa in tensile stiffness and strength, respectively, were fabricated with a very high fiber volume content of up to 80%. The high fiber volume contents led to mechanical interlocks between neighboring fibers and made the need for an additional matrix unnecessary. The water-based laminate process is cost-efficient and scalable and additionally allows one to make full use of delignified wood’s formability by producing shaped parts for various applications.

Novel Analytical Model of Stress Concentration around Broken Fibers of Unidirectional Composite Plate

During the fiber fracture of unidirectional composite a distribution of stress around the neighbored fibers happens, this mechanism is called the local redistribution efforts. Referring to the "shear lag" method, the researches wanted to predict the stress concentration in the surrounding area of broken fibers as well as the longitudinal resistance of the unidirectional composite which presents a fiber breaking. The goal of this paper is to develop a new probabilistic model of unidirectional composite plate to calculate the stress concentration at the broken fibers and their neighboring fiber intact. The "shear lag" method has been generalized to see the broken fibers interference on the stress concentration factor variation of surrounding sound fibers.

Correlation and diffusion breaking in the failure process of composite materials

Fiber bundle model is one of the important statistical and theoretical physics approaches to investigate the fracture and breakdown of heterogeneous material extensively used both by the engineering and physics community. In this paper, using the correlation function and its properties, we study the diffusion of the failure process in composite materials that consist of a set of with randomly oriented fibers loaded by an external constant total load. The investigation is based on fiber bundle model where the fibers are randomly oriented; each fiber is subject only the cosine component of the external load, and when it fails, its load is shared by surviving neighboring fibers according to the local load sharing rule (LLS). The failure process ensures an advancing interfacial fracture and the areas of the damaged regions increases with time until a final crack of material. By using the correlation function of the fraction of broken fibers, we study the diffusion properties of micro crack created in the composite materials. The results show that the correlation decreases exponentially with time and decreases with both of applied load and temperature. We calculate then the effective diffusion coefficient cracks which increase exponentially with applied load and linearly with the temperature. The failure time tf of the materials decrease with temperature as a power law. Obtained results are compared with the one of the classical model consist of a set of parallel fibers.

Modelling of composite materials energy by fiber bundle model

In this paper, the fiber energy in composite materials, subject to an external constant load, is studied. The investigation is done in the framework of fiber bundle model with randomly oriented fibers. The charge transfer is done only between neighboring close fibers according to the local load sharing. During the breaking process, the fibers expand, increasing their elastic energy, but when the fiber breaks, it loses its link with its neighboring fibers reducing the cohesive energy of the materials. The results show that the material energy presents one maximal peak at cross over time which decreases linearly with the applied force and scales with the lifetime of the material. However, the temperature does not have a remarkable effect on the material energy variation. In addition, the link density fiber decreases exponentially with time. The characteristic time of the obtained profile decreases with the applied force. Moreover, this density decreases with applied forces according to the Lorentz law with a remarkable change at critical force value.

Scaling law in avalanche breaking of composite materials

PurposeThe fibers are loaded by the cosine component of the external load, when a fiber fails, and due to the local load-sharing nature, its force is shared by surviving neighboring fibers. The results show that the system presents a greater resistance and toughness toward the applied load compared to the classical one.Design/methodology/approachIn this paper, the authors adopt the dynamics of a local load-sharing fiber bundle model in two dimensions under an external load to study scaling law in failure process of composite materials with randomly oriented fibers. The model is based on the fiber bundle model where the fibers are randomly oriented. The system is different to the classical one where the fibers are arranged in parallel with the applied load direction.FindingsThe evolution time of the fraction of broken fiber is described by an exponential law with two characteristic times. The latter decrease linearly and exponentially respectively with both applied load and temperature.Originality/valueScaling behavior of the broken fiber numbers with the size system shows that the system exhibits a scaling law of Family–Vicsek model with universal exponents.

Force-exerting perpendicular lateral protrusions in fibroblastic cell contraction

Aligned extracellular matrix fibers enable fibroblasts to undergo myofibroblastic activation and achieve elongated shapes. Activated fibroblasts are able to contract, perpetuating the alignment of these fibers. This poorly understood feedback process is critical in chronic fibrosis conditions, including cancer. Here, using fiber networks that serve as force sensors, we identify “3D perpendicular lateral protrusions” (3D-PLPs) that evolve from lateral cell extensions named twines. Twines originate from stratification of cyclic-actin waves traversing the cell and swing freely in 3D to engage neighboring fibers. Once engaged, a lamellum forms and extends multiple secondary twines, which fill in to form a sheet-like PLP, in a force-entailing process that transitions focal adhesions to activated (i.e., pathological) 3D-adhesions. The specific morphology of PLPs enables cells to increase contractility and force on parallel fibers. Controlling geometry of extracellular networks confirms that anisotropic fibrous environments support 3D-PLP formation and function, suggesting an explanation for cancer-associated desmoplastic expansion.

Development of a novel high quantum efficiency MV x-ray detector for image-guided radiotherapy: A feasibility study.

PurposeTo develop a new scintillating fiber‐based electronic portal imaging device (EPID) with a high quantum efficiency (QE) while preserving an adequate spatial resolution.MethodsTwo prototypes were built: one with a single pixel readout and the other with an active matrix flat‐panel imager (AMFPI) for readout. The energy conversion layer of both prototypes was made of scintillating fiber layers interleaved with corrugated lead sheets to form a honeycomb pattern. The scintillating fibers have a diameter of 1 mm and the distance between the centers of neighboring fibers on the same layer is 1.35 mm. The layers have 1.22 mm spacing between them. The energy conversion layer has a thickness of 2 cm. The modulation transfer function (MTF), antiscatter properties and sensitivity of the detector with a single pixel readout were measured using a 6‐MV beam on a LINAC machine. In addition, a Monte Carlo simulation was conducted to calculate the zero‐frequency detective quantum efficiency (DQE(0)) of the proposed detector with an active matrix flat‐panel imager for readout.ResultsThe DQE(0) of the proposed detector can be 11.5%, which is about an order of magnitude higher than that of current EPIDs. The frequency of 50% modulation (f50) of the measured MTF is 0.2 mm-1 at 6 MV, which is comparable to that of video‐based EPIDs. The scatter to primary ratio (SPR) measured with the detector at 10 cm air gap and 20 × 20 cm2 field size is approximately 30% lower than that of ionization chamber–based detectors with a comparable QE. The detector noise which includes the x‐ray quantum noise and absorption noise is much larger than the electronic noise per pixel of the flat‐panel imager at a dose of less than two LINAC pulses. Thus, the proposed detector is quantum noise limited down to very low doses (∼a couple of radiation pulses of the LINAC). A proof‐of‐concept image has been obtained using a 6‐MV beam.ConclusionsThis work indicates that by using scintillating fibers and lead layers it is possible to increase the thickness of the detecting materials, and therefore the QE or the DQE(0) of the detector, while maintaining an adequate spatial resolution for MV x‐ray imaging. Due to the use of lead as the spacing material, the new detector also has antiscatter property, which will help improve the signal‐to‐noise ratio of the images. Further investigation to optimize the design of the detector and achieve a better combination of DQE and spatial resolution is warranted.