Expansion Of Fibers Research Articles

Suprachiasmatic nucleus VIPergic fibers show a circadian rhythm of expansion and retraction

In animals, overt circadian rhythms of physiology and behavior are centrally regulated by a circadian clock located in specific brain regions. In the fruit fly Drosophila and in mammals, these clocks rely on single-cell oscillators, but critical for their function as central circadian pacemakers are network properties that change dynamically throughout the circadian cycle as well as in response to environmental stimuli.1,2,3 In the fly, this plasticity involves circadian rhythms of expansion and retraction of clock neuron fibers.4,5,6,7,8,9,10,11,12,13,14 Whether these drastic structural changes are a universal property of central neuronal pacemakers is unknown. To address this question, we studied neurons of the mouse suprachiasmatic nucleus (SCN) that express vasoactive intestinal polypeptide (VIP), which are critical for the SCN to function as a central circadian pacemaker. By targeting the expression of the fluorescent protein tdTomato to these neurons and using tissue clearing techniques to visualize all SCN VIPergic neurons and their fibers, we show that, similar to clock neurons in the fly, VIPergic fibers undergo a daily rhythm of expansion and retraction, with maximal branching during the day. This rhythm is circadian, as it persists under constant environmental conditions and is present in both males and females. We propose that circadian structural remodeling of clock neurons represents a key feature of central circadian pacemakers that is likely critical to regulate network properties, the response to environmental stimuli, and the regulation of circadian outputs.

Penetration, expansion and corrosion behavior of fiber reinforced pipe in fluid containing supercritical CO2

Penetration, expansion and corrosion behavior of fiber reinforced pipe in fluid containing supercritical <scp>CO₂</scp>

Study on impact properties of carbon/kevlar fiber hybrid composites

AbstractIn this article, carbon/kevlar hybrid composites were prepared using Vacuum Assisted Resin Infusion (VARI). The sandwich structure with plain carbon weave fabric as the core layer and plain kevlar weave fabric as the surface layer was selected as reinforcement and the solution of epoxy resin and curing agent was selected as matrix. The low velocity impact experiment and compression after impact (CAI) experiment were carried out on the samples at different hybrid ratio and different temperatures, and the mechanical response on the impact loads were analyzed respectively. The results show that the specimen can limit the delamination defect expansion of the surface kevlar fiber as the carbon fiber used as the core layer, which reduce the delamination defect area and improve the impact resistance of the sample. The toughness of the sample improves the brittle failure mode, that is, the sample still has a certain bearing capacity after the load exceeds the maximum strength, the sandwiched composites presents a positive hybrid effect. With the increase of temperature, the matrix was obviously softened, the macromolecular movement in the system was intensified, the three‐dimensional network macromolecular structure of the matrix and the fiber/matrix interface properties were damaged, and the mechanical properties showed an obvious downward trend. As far as the influences of hybrid ratio and temperature on impact behavior of composite are concerned, it lay a theoretical foundation for the industrial application of carbon/kevlar hybrid composites.Highlights The sandwiched structure was used to design the composites, which greatly improves the impact properties of the specimens. The impact properties and compression after impact properties at different hybrid ratios and different temperatures were studied. Based on the hybrid effect and temperature effect, the impact failure mechanism of the sample was analyzed.

Estimation of transverse thermoelastic properties of polyimide fibers based on micromechanical models

The determination of the thermoelastic properties of polyimide (PI) fibers is important for their applications, however, these properties are difficult to measure directly, especially the transverse thermoelastic properties. Here, the transverse thermoelastic properties of PI fibers, including transverse Young's modulus (2.12 GPa), shear modulus (0.94 GPa), Poisson's ratio (0.05), and coefficient of thermal expansion (45.68 μm/m°C), were estimated by combining dynamic and static thermo-mechanical techniques, as well as various relevant micromechanical models. The transverse Young's modulus of PI fibers was only 1/46th of the longitudinal one, and the transverse coefficient of thermal expansion of PI fibers was positive, unlike the longitudinal one, which was negative, showing the typical anisotropy of PI fibers. Finally, the thermoelastic properties of the PI fibers were in turn used to predict the thermoelastic behavior of the PI fiber-reinforced composites, thus validating their effectiveness.

Making Composite Materials from Unsaturated Polyester and Coconut Fiber Judging from Mechanical Properties

Making combined materials that consist of unsaturated polyester and coconut fiber is the target of this research. The samples were tested by tensile and hardness tests before and after warm-up, and obtained by the result was that the trend value of hardness of unsaturated polyester+coconut fiber experienced proportional degradation with the addition of the composition of coconut fiber. The composition of 3% coconut fiber+97% unsaturated polyester has the highest hardness value, reaching 46,7 kg/mm2, and downhill becomes 43,1 kgf/mm2 moment heated at a temperature of 500C for 1 hour. Analog to the tensile test, 3% coconut fiber + 97% unsaturated polyester composition has the highest ultimate tensile strength and yield point. Adding fiber can boost the elasticity modulus, but the warm-up treatment causes the expansion of coconut fiber. The result is that the value of the tensile and hardness of the polyblend will go downhill.

Influence of Bamboo Fiber Content on the Properties of Asphalt Mixtures

Inspecting what how much bamboo fiber means for the attributes of asphalt mixtures and searching for ways of further developing maintainability and execution. To assess the impacts of bamboo fibers on significant qualities including soundness, rutting opposition, weakness conduct, and dampness helplessness, asphalt details coordinate these sustainable and ecologically harmless fibers. This review evaluated the presentation improving use of bamboo fiber, a new expansion to the regular fiber family, in stone matrix asphalt (SMA) and dense-grade (DG) mixes. As well as having a harsh surface like that of a typical lignin fiber, bamboo fiber has a high rigidity in the fiber course. Furthermore, bamboo fiber has satisfactory warm dependability, an issue with plant-based materials that is normally raised. The ideal asphalt cover contents for DG and SMA mixtures with differing measures of bamboo fiber were picked utilizing the Marshall blend plan procedure. Utilizing the wheel following test, inundation Marshall test, freeze-defrost cycle test, and three-point twisting bar test, separately, the impacts of bamboo fiber on blend dampness helplessness, rutting, and low-temperature breaking execution were surveyed. The presentation of the previously mentioned blend was fundamentally worked on by the expansion of bamboo fiber, as indicated by test results. All in all, blends including bamboo fiber exhibited execution that was either tantamount to or better than those containing polyester and lignin fiber, proposing that bamboo fiber can be utilized in asphalt mixtures.

In-plane thermal expansion behavior of M55J carbon fiber reinforced SiC matrix composite

With the rapid development of high-precision ultra-stable spacecraft, the absolute values of coefficients of thermal expansion (CTE) of carbon fiber reinforced SiC matrix composite (C/SiC) are required to be closer to 10−7 K−1 or even lower. In this work, high-modulus and low-expansion M55J carbon fiber was selected to replace T300 carbon fiber as the reinforcement to decrease the CTE of C/SiC. The interfacial region, pore distribution and microstructure evolution during the densification process were investigated. With the replacement of T300 carbon fiber by M55J carbon fiber as the reinforcement, axial thermal residual stress in SiC matrix can increase to 378 ± 26 MPa, resulting in the generation of matrix microcracks. This can reduce the constraint of matrix to carbon fiber and provide expansion space for M55J-C/SiC. Therefore, the average in-plane technical CTE of C/SiC in the range of −20 to 50 °C can be reduced from 1.09 × 10−6 to 0.34 × 10−6 K−1.

Simulation and parameter prediction model of rheological properties of fiber reinforced concrete

For higher concrete strength, fiber-reinforced concrete is a hot research topic. In the transportation process of fiber-reinforced concrete, flow characteristics are critical indicators of pumping fiber-reinforced concrete. In this paper, firstly, the rheological characteristics of steel fiber-reinforced concrete are measured based on the small slump cylinder. The rheological parameters, such as slump and expansion of steel fiber reinforced concrete with different proportions, are analyzed, and the rheological properties of the slurry are tested by rheometer. Secondly, to realize the effective prediction of the rheological parameters of steel fiber reinforced concrete, the Fluent numerical simulation software in computational fluid dynamics (CFD) is used to simulate the rheological properties of concrete in the micro slump cylinder. By comparing with the experimental results, the simulation results are in good agreement with the actual results, and the maximum error is only 2 mm, which verifies the accuracy of the numerical model. Finally, based on the test results of 25 groups of rheological parameters of fiber-reinforced concrete as the original data set, the prediction model of rheological parameters of fiber-reinforced concrete based on Sparrow Search Algorithm - Xtreme Gradient Boosting (SSA-XGBoost) is established. The prediction results show that SSA-XGBoost has high applicability in the prediction of the dynamic yield stress of the mixture, and the experimental value R2 is as high as 0.99.

To Investigate the Mechanical Properties of Concrete by Partial Replacement of Cement with Ceramic Tiles Waste Powder and Addition of Jute Fiber

Abstract: The need for natural and non-renewable resources has grown as a result of the continuing development of society and human endeavours. As a result, the amount of industrial solid waste products kept growing. The most widely used man-made material in the world, concrete, has generated a lot of interest as a potential method for recycling solid waste. About the same amount of CO2 is produced during the manufacture of 1 tonne of Portland cement. The cement sector is thought to be responsible for 5% to 8% of yearly global greenhouse gas emissions. The use of waste materials in our current concrete can lessen the environmental pollution. Put the scenario in a critical state employing alternate approaches and come up with a better material recycling solution. As additional cementitious materials, a variety of by-products, including fly ash, slag, and silica fume, are successfully used every day in the manufacturing of concrete (SCM). According to the research it has been found that about 150 million tons of ceramic have been produced per year. From that total production, around 25% to 35% has become waste material without recycling from the ceramic industry at present. The ceramic powder has various advantages such as cost - saving, energy Saving and reduces the hazards materials to the environment. Ceramic waste can be used in concrete to increase the compressive strength and physical and chemical properties of concrete. It has been established that the addition of evenly distributed, tightly spaced Fibers to concrete will significantly enhance its static and dynamic properties and act as a crack arrester. Concrete that has been reinforced with fibrous material, or fiber-reinforced concrete (FRC), has a higher structural stability. It is important to note that jute is sometimes referred to as the golden fibre owing to its high cash value and its colour. It improves the shear and punching resistance of concrete, aid in recovering post-cracking strength losses, increases the toughness and become an effective way for reinforcement. In this experimental work, partial replacement of cement by ceramic tiles waste powder by percentages of 0%, 15%, 20%, 25% and 30% with expansion of Jute Fiber at different rate as 0%, 0.25%, 0.50%, 0.75% and 1.0% are done to make sustainable concrete. All specimens were cured for 7days and 28 days before testing. From the study it has been observed that the test results shows optimum proportion for concrete mix and are within acceptable limits.

On the Residual Stresses and Fracture Toughness of Glass/Carbon Epoxy Composites.

The resistance to delamination in polymer composite depends on their constituents, manufacturing process, environmental factors, specimen geometry, and loading conditions. The manufacturing of laminated composites is usually carried out at an elevated temperature, which induces thermal stresses in composites mainly due to a mismatch in the coefficient of thermal expansion (CTE) of fiber and matrix. This work aims to investigate the effect of these process-induced stresses on mode-I interlaminar fracture toughness (GI) of Glass-Carbon-Epoxy (GCE) and Glass-Epoxy (GE) composites. These composites are prepared using a manual layup technique and cured under room temperature, followed by post-curing using different curing conditions. Double cantilever beam (DCB) specimens were used to determine GI experimentally. The slitting technique was used to estimate residual stresses (longitudinal and transverse direction of crack growth) inherited in cured composites and the impact of these stresses on GI was investigated. Delaminated surfaces of composites were examined using a scanning electron microscopy (SEM) to investigate the effect of post-curing on the mode-I failure mechanism. It was found that GI of both GE and GEC composites are sensitive to the state of residual stress in the laminas. The increase in the GI of laminates can also be attributed to an increase in matrix deformation and fiber–matrix interfacial bond with the increase in post-curing temperature.

Progress on Materials Reinforcement using Mechanically Defibrillated Cellulose Nanofibers

Cellulose nanofibers (CNFs) are highly crystalline, fibrous materials with a high aspect ratio of long cellulose molecules linked together with strong hydrogen bonds. These long cellulose molecules are incorporated into hemicellulose and lignin, the cell walls of higher plants. The modulus of elasticity of CNF remains constant between −200 °C and +200 °C. However, the linear coefficient of thermal expansion of cellulose fibers was 0.17 ppm/K, which is comparable to that of quartz glass. Further, CNFs have a thermal conductivity in the same order of magnitude as glass. Therefore, they are promising next-generation fiber owing to the excellent mechanical and thermal properties, sustainability, and biodegradability of CNF. Most studies on using CNFs to increase strength have focused on polymer matrix composites, particularly biodegradable polymers. However, it is difficult to increase the strength of materials using CNFs due to the agglomeration of CNFs. Compared to other composite materials, the uniform dispersion of nanosized CNFs is crucial. This article reports that CNFs may behave not as reinforcing fibers but as cross-linking agents to strengthen the polymer when the amount of CNFs is very small in polymer matrix composites, and the addition of CNFs is also effective in strengthening silk yarn and Ti. The mechanical properties of the ceramic green bodies can be increased using CNFs as an auxiliary agent in ceramic slurry. Moreover, the fabrication of composite materials using CNFs is essential for expanding the CNFs applications.

A cholinergic neuroskeletal interface promotes bone formation during postnatal growth and exercise.

SummaryThe autonomic nervous system is a master regulator of homeostatic processes and stress responses. Sympathetic noradrenergic nerve fibers decrease bone mass, but the role of cholinergic signaling in bone has remained largely unknown. Here, we describe that early postnatally, a subset of sympathetic nerve fibers undergoes an interleukin-6 (IL-6)-induced cholinergic switch upon contacting the bone. A neurotrophic dependency mediated through GDNF-family receptor-α2 (GFRα2) and its ligand, neurturin (NRTN), is established between sympathetic cholinergic fibers and bone-embedded osteocytes, which require cholinergic innervation for their survival and connectivity. Bone-lining osteoprogenitors amplify and propagate cholinergic signals in the bone marrow (BM). Moderate exercise augments trabecular bone partly through an IL-6-dependent expansion of sympathetic cholinergic nerve fibers. Consequently, loss of cholinergic skeletal innervation reduces osteocyte survival and function, causing osteopenia and impaired skeletal adaptation to moderate exercise. These results uncover a cholinergic neuro-osteocyte interface that regulates skeletogenesis and skeletal turnover through bone-anabolic effects.

Carbon nanotube reinforced pyrocarbon matrix composites with high coefficient of thermal expansion for self-adapting ultra-high-temperature ceramic coatings

The mismatch in the coefficients of thermal expansion (CTE) of the carbon fiber reinforced pyrocarbon (Cf/C) composites and their thermal barrier coatings (TBCs) has significantly restricted the service life of Cf/C composites in high-temperature environments. Owing to the high CTE of TBCs, it is vital to find a material with similar mechanical properties and higher CTE than Cf/C composites. In this work, carbon nanotube reinforced pyrocarbon (Ct/C) nanocomposites with high CTEs were prepared to self-adapt to the TBCs. Different CTEs (∼4.0–6.5 × 10−6/°C) were obtained by varying the carbon nanotube (CNT) content of the Ct/C composites. Owing to the decreased mismatch in the CTEs, no cracks were formed in the TBCs (SiC and HfB2-SiC-HfC coatings) deposited on the Ct/C composites. After heat treatment at 2100 °C, several wide cracks were found in the TBCs on the Cf/C composite, whereas the TBCs on the Ct/C composites were intact without cracks. We found that the CTE-tunable Ct/C composites can self-adapt to different TBCs, protecting the composites from oxidation at high temperatures.

ポリアミド繊維の可逆的な熱膨張／収縮に関する研究

ポリアミド繊維の可逆的な熱膨張／収縮に関する研究

Thermally drawn rechargeable battery fiber enables pervasive power

The increasing demand for mobile computing, communications, and robotics presents a growing need for suitable portable power solutions in non-flat customized electronic devices. Fibers as fundamental building blocks of fabrics and 3D-printed objects provide unique opportunities for developing pervasive multidimensional power systems. The characteristic small diameter (<10−3 m) and high aspect ratios (>106) of fibers and expansion of fibers into 2D and 3D power systems necessitate ultra-long lengths to meet the energy specifications of portable electronic systems. Here, we present a Li-ion battery fiber, fabricated for the first time using a thermal drawing method which occurs with simultaneous flows of multiple complex electroactive gels, particles, and polymers within protective flexible cladding. This top-down approach allows for the production of fully-functional and arbitrarily long lithium-ion fiber batteries. The continuous 140 m fiber battery demonstrates a discharge capacity of ∼123 mAh and discharge energy of ∼217 mWh. The scalability and material tunability of these fibers position them for use in varied non-planar electronic systems, including a 1D-flexible electronic fiber, a 2D-large-scale machine woven electronic fabric (∼1.6 m2), and a 3D-printed structural electronic system. The fiber battery satisfies the requirements of portable electronics systems as it is machine washable, flexible, usable underwater, and fire/rupture-safe. We have demonstrated the powering of a submarine drone, LiFi fabric, and flying drone communication through different rechargeable fiber battery schemes, which paves the way for the emergence of the pervasive battery-powered electronics.

A virtual scale approach to multi-scale calculations and its application in fiber-reinforced composites

With the development of materials science and technology into the nano-/micro-world, multi-scale problems have become a research focus. Multi-scale calculations usually select a periodic structure as a representative unit with a certain physical meaning and can represent the material properties at a given scale. However, due to the large number of representative elements with complex shape and boundary conditions, the workload of multi-scale calculations is normally huge. In the present effort, a novel virtual scale method is proposed for multi-scale calculations. To demonstrate the validity and significance of the new algorithm, multi-scale calculations have been carried out for the prediction of properties of the ever-popular fiber reinforced composite materials. The equivalent elastic modulus, Poisson's ratio and coefficient of thermal expansion (CTEs) of fiber reinforced plastic in different scales predicted by the new method have been compared with those predicted by the well-established finite element method (FEM) and checked against the experimental results. The good agreements offer solid proof in terms of the validity of the newly developed virtual scale method. In principle, the method can be extended to tackle all multi-scale problems.

Mechanism for anisotropic thermal expansion of polyamide fibers

This paper examines the validity of the contribution of entropy elasticity, which has been vaguely considered to be the main cause of the thermal expansion behavior of the untwisted fiber. Thereafter, we indicate the inconsistencies and propose a new possible physical principle. A new high-order structural model that can effectively cause anisotropic thermal expansion of fibers is proposed. The observed results verify our proposal, and further show its validity and correctness. The twisted fiber actuator, which has garnered significant attention in recent years, is driven by the anisotropic thermal expansion of an untwisted fiber, which is the precursor of the twisted fiber. Analyzing the physical principle of the thermal expansion behavior of the untwisted fiber is to obtain the knowledge for improving performance of the actuator.

Development of a measurement system for the thermal expansion of a carbon fiber

Development of a measurement system for the thermal expansion of a carbon fiber

Preparation of 3D porous graphene fibrous materials via thermal expansion method with open flame treatment

In this study, we report a simple, rapid, and efficient strategy for the fabrication of 3 D porous graphene fibrous materials(EGF) via open flame thermal expansion of RGO fiber(GF), which was prepared via chemical reduction and self-assembly of graphene oxide in our previous work. The 3 D EGF possesses high specific surface area and capacitance up to 1674.66 m2/g and 110 F/g, good electrical conductivity and excellent mechanical properties. Furthermore, SEM, TEM, XRD, FT-IR etc. were used to characterize and analyze the properties of EGF.

Combined effect of flax fibers and steel fibers on spalling resistance of ultra-high performance concrete at high temperature

This paper investigated the combined effects of flax fibers and steel fibers on spalling behavior, residual permeability, and compressive strength of ultra-high performance concrete (UHPC) after exposure to elevated temperature. Thermal analysis and microstructure observation were conducted to study the mechanism of the hybrid fibers in spalling prevention. The findings showed that the combined use of steel and flax fibers could completely prevent spalling of UHPC with relatively low fiber content, while solely using either steel fibers or flax fibers did not prevent spalling even with high fiber contents. The synergistic effect of hybrid flax and steel fibers on enhancing spalling resistance of UHPC was attributed to the increase in permeability from flax fibers and the bridging effect of steel fibers under elevated temperature. The mechanism of enhanced permeability of UHPC relied on two aspects: shrinkage of flax fibers at high temperature created interfacial gaps between the flax fibers and the matrix and microcracks created by the expansion of steel fibers enhanced the connectivity of these gaps and the microcracks. The bonding between steel fibers and matrix retained at a certain level at temperatures below 400 °C, which could also help mitigate spalling. It was also found that the combination of steel and flax fibers could compromise the reduction in compressive strength caused by the addition of flax fibers.