Fiber Junctions Research Articles

Stretchable and Breathable Electroluminescent Displays Based on Ultrathin Nanocomposite Designs.

Stretchable electroluminescent devices represent an emerging optoelectronic technology for future wearables. However, their typical construction on sub-millimeter-thick elastomers has limited moisture permeability, leading to discomfort during long-term skin attachment. Although breathable textile displays may partially address this issue, they often have distinct visual appearances with discrete emissions from fibers or fiber junctions. This study introduces a convenient procedure to create stretchable, permeable displays with continuous luminous patterns. The design utilizes ultrathin nanocomposite devices embedded in a porous elastomeric microfoam to achieve high moisture permeability. These displays also exhibit excellent deformability, low-voltage operation, and excellent durability. Additionally, the device is decorated with fluorinated silica nanoparticles to achieve self-cleaning and washable capabilities. The practical implementation of these nanocomposite devices is demonstrated by creating an epidermal counter display that allows intimate integration with the human body. These developments provide an effective design of stretchable and breathable displays for comfortable wearing.

Influence of Complex Geometries on Damage Tolerance of Porous Carbon Fiber Network

Porous materials exhibit a variety of attractive functional properties for aerospace applications, such as low density and low thermal conductivity. However, they must also be mechanically robust and damage tolerant to fully realize their potential. Currently, it is costly and time-consuming for testing under service conditions, therefore, computational models are a good path forward. Due to the inherent microstructural stochasticity of these structures, however, their behavior is difficult to effectively model without detailed experimental studies for validation and benchmarking. To that end this study investigates the mechanical properties of a porous carbon fiber network and ties together the global macroscopic observations to the local mesoscale behaviors dictated by individual fibers and fiber junctions. Strain localization was observed using digital image correlation (DIC) and tied to features within the macroscopic stress–strain plots. Work to quantify the impact of the addition of complex geometries (e.g., cracks and through-holes) on mechanical reliability was conducted. The defects resulted in distinct macroscale mechanical characteristics and mesoscale deformation behaviors, depending on defect type and loading orientation. These results provide broad experimental data to inform and validate modeling approaches to accurately predict and tailor the reliability of porous parts under service conditions.

ZrO2/SiO2/C nanofiber aerogels with enhanced mechanical and thermal insulation properties fabricated by freeze casting

Because of the inherent high-temperature resistance, the application of ZrO2 nanofiber aerogels in thermal insulation is promising. However, the contradiction between mechanical and thermal insulation properties has limited its applications. In the present work, nanofiber aerogels of ZrO2/SiO2/C with enhanced thermal insulation and compressive strength were successfully prepared by freeze-casting using tetraethoxysilane (TEOS) as a binder. The effect of TEOS content on the microstructure, compressive and thermal insulation properties was investigated. The porosity of the fabricated aerogels is higher than 97.3 %. The pore structure exhibits hierarchical characteristics, with honeycomb pores on the micro-scale and mesopores on the nano-scale. Part of the SiO2 phases generated by TEOS hydrolysis bond ZrO2 nanofiber to form fiber junctions, while the others cover the surface of ZrO2 nanofibers forming core-shell structure. With the increase of TEOS content, ZrO2/SiO2/C nanofiber aerogels showed a slightly decrease in thermal conductivity to a lower value of 0.032 W m−1 K−1 and an increase in compressive stress to 11.9 KPa. The thermal insulation mechanism and deformation mode during compression of aerogels were analyzed. This study not only provide ZrO2/SiO2/C nanofiber aerogels with both enhanced mechanical and thermal insulation properties, but also can guide the design and fabrication of other ceramic aerogels with excellent properties.

In-situ formation of CoFe2O4 within electrospun PVDF scaffolds to achieve a high β content and high magnetic hyperthermia ability

This study aimed to enhance the piezoelectric and ferromagnetic properties of electrospun poly (vinylidene fluoride) (PVDF) scaffold by in-situ formation of CoFe2O4 (CFO) within the fibers. To evaluate the effects of CFO on the microstructures and properties of the scaffolds, varying amounts of CFO were utilized (x = 0 to 10 wt %). The results demonstrated the successful formation of CFO at the fiber junctions (x < 2), while the agglomerates were formed within the large fibers (2 < x < 10). The in-situ formation of CFO was confirmed by the energy dispersive spectroscopy (EDS) analysis and X-ray diffraction (XRD) patterns. The highest fraction of β phase was achieved at 0.735 and 0.960 for the PVDF-CFO scaffold (x = 1) based on the XRD and Fourier-transform infrared technique (FTIR) results. The dielectric constant, magnetic properties, and piezoelectric sensitivity of the PVDF scaffold were enhanced with the in-situ formation of CFO. The highest coercivity and piezoelectric sensitivity were observed at x = 1. In-vitro analysis of the scaffolds revealed that the highest blood compatibility and antioxidant activity could be achieved through the in-situ formation of 1 wt % of CFO. Eventually, the magnetic hyperthermia ability of scaffolds was evaluated, and the PVDF-CFO scaffolds were recognized as the high potential materials for the hyperthermia treatment according to the specific absorption rate (SAR) of 25–44 W g−1 and intrinsic loss power (ILP) factor of 5–9 nH m2·kg−1. Our findings suggest that by controlling the in-situ formation of CFO within the PVDF electrospun scaffold, the cancer cell eradication process can be performed with a minimum dosage of the ferroelectric-ferromagnetic magnetic composite.

The YAP1/TAZ-TEAD transcriptional network regulates gene expression at neuromuscular junctions in skeletal muscle fibers.

We examined YAP1/TAZ-TEAD signaling pathway activity at neuromuscular junctions (NMJs) of skeletal muscle fibers in adult mice. Our investigations revealed that muscle-specific knockouts of Yap1 or Taz, or both, demonstrate that these transcriptional coactivators regulate synaptic gene expression, the number and morphology of NMJs, and synaptic nuclei. Yap1 or Taz single knockout mice display reduced grip strength, fragmentation of NMJs, and accumulation of synaptic nuclei. Yap1/Taz muscle-specific double knockout mice do not survive beyond birth and possess almost no NMJs, the few detectable show severely impaired morphology and are organized in widened endplate bands; and with motor nerve endings being mostly absent. Myogenic gene expression is significantly impaired in the denervated muscles of knockout mice. We found that Tead1 and Tead4 transcription rates were increased upon incubation of control primary myotubes with AGRN-conditioned medium. Reduced AGRN-dependent acetylcholine receptor clustering and synaptic gene transcription were observed in differentiated primary Tead1 and Tead4 knockout myotubes. In silico analysis of previously reported genomic occupancy sites of TEAD1/4 revealed evolutionary conserved regions of potential TEAD binding motifs in key synaptic genes, the relevance of which was functionally confirmed by reporter assays. Collectively, our data suggest a role for YAP1/TAZ-TEAD1/TEAD4 signaling, particularly through TAZ-TEAD4, in regulating synaptic gene expression and acetylcholine receptor clustering at NMJs.

Granular flow in novel Octet shape-based lattice frame material

Abstract Moving packed-bed heat exchanger in concentrated solar power (CSP) plants involves heat transfer between heated falling particles and supercritical carbon dioxide. The overall effective thermal conductivity of the moving packed bed and particle-side channel contact resistances are still the bottlenecks in achieving the desirable thermal transport levels. To this end, a novel moving packed bed heat exchanger consisting of Octet lattice packed between the walls of the particle-side channel is proposed in this study. Granular flow analysis in Octet lattice moving-packed bed heat exchanger (OLHX) was conducted through experiments and DEM-based numerical simulations. The experimental images clearly demonstrated stagnation regions upstream of lattice fibers, void regions downstream of the fiber junctions and wavy type unobstructed flow on lateral sides of the fibers. DEM simulations were successful in capturing all these critical flow phenomena. Larger flow velocities were observed on the lateral sides of the fibers in the simulations. Also, when the particles in the silo were emptied, the final images showed accumulation of particles on the inter-fiber as well as fiber-channel wall junctions. Moreover, the fiber connections resulted in some regions devoid of the particle contact on the channel endwall which means that these regions would suffer from poor thermal exchange. The overall mass flow rate increased with increasing porosity for a fixed particle diameter.

Study of Air Pressure on Arc Ion Plating on Epoxy Resin Matrix Composites at Meter Range Working Distance

The metal film was deposited on the surface of epoxy resin based composite by arc ion plating technology. The distribution of metal ions at the interface of matrix was simulated. The growth mode of metal ions on the composite surface was analyzed. The deposition rate, surface morphology and membrane base bonding strength were investigated. The results show that the transition layer of nm level will be formed on the surface of composite materials, and the larger the sputtering energy of metal ions, the deeper the distribution on the surface of composite materials. Nucleation occurs at the junction of fiber and resin matrix, and the fusion of nucleated particles grows along the fiber boundary with the increase of deposition time, and extends to the vertical fiber direction. Finally, the particles between fibers and the particles on the boundary gradually expand and merge into layered films. The working pressure decreased, the deposition rate of metal increased, the grain size decreased, the large particles on the surface of the metal coating decreased, and the bonding strength of the film base increased.

Experimental verification of the additivity between the barrel droplet's drag force and the fiber number

AbstractResearch on the single fiber scale has an essential application value in the coalescence field. The study of the droplets' behavior on the fiber junctions can provide support data for optimizing the coalescer's drainage performance on the macroscopic scale. However, relevant research focusing on the force change of droplets during the transition from a single fiber to multifiber is relatively scarce. The droplet migration platform was built using the Lavision particle image velocimetry system, which can observe the behavior of droplets on fibers. The force and fiber number relationship were analyzed when the droplets were separated from the fiber junctions. Two detachment modes were observed during separation. Furthermore, the drag force satisfied the additivity theorem by increasing the number of fibers under the same detachment mode. In addition, the minimum Reynolds number prediction model was established under two separation forms, which had good prediction compared to the experimental data.

Localization of FGF21 Protein and Lipid Metabolism-Related Genes in Camels

With the ability to survive under drought and chronic hunger, camels display a unique regulation characteristic of lipid metabolism. Fibroblast growth factor (FGF) 21 is a peptide hormone that regulates metabolic pathways, especially lipid metabolism, which was considered as a promising therapeutic target for metabolic diseases. To understand the FGF21 expression pattern and its potential relationship with lipid metabolism in camels, this study investigated the distribution and expression of FGF21, receptor FGFR1, and two lipid metabolism markers, leptin and hormone-sensitive lipase (HSL), using an immunohistochemistry (IHC) assay. The results showed that FGF21 was widely expressed in camel central nerve tissue and peripheral organs but absent in lung and gametogenic tissue, including the testis, epididymis, and ovary. In striated muscle, FGF21 is only present at the fiber junction. FGFR1 is expressed in almost all tissues and cells, indicating that all tissues are responsive to FGF21 and other FGF-mediated signals. Leptin and HSL are mainly located in metabolic and energy-consuming organs. In the CNS, leptin and HSL showed a similar expression pattern with FGFR1. In addition, leptin expression is extremely high in the bronchial epithelium, which may be due to its role in the immune responses of respiratory mucosa, in addition to fat stores and energy balance. This study found that FGF21 showed active expression in the nervous system of camels, which may be related to the adaptability of camels to arid environments and the specific regulation of lipid metabolism. This study showed a special FGF21-mediated fat conversion pattern in camels and provides a reference for developing a potential therapeutic method for fat metabolism disease.

Calcium-dependent cAMP mediates the mechanoresponsive behaviour of endothelial cells to high-frequency nanomechanostimulation

The endothelial junction plays a central role in regulating intravascular and interstitial tissue permeability. The ability to manipulate its integrity therefore not only facilitates an improved understanding of its underlying molecular mechanisms but also provides insight into potential therapeutic solutions. Herein, we explore the effects of short-duration nanometer-amplitude MHz-order mechanostimulation on interendothelial junction stability and hence the barrier capacity of endothelial monolayers. Following an initial transient in which the endothelial barrier is permeabilised due to Rho–ROCK-activated actin stress fibre formation and junction disruption typical of a cell's response to insults, we observe, quite uniquely, the integrity of the endothelial barrier to not only spontaneously recover but also to be enhanced considerably—without the need for additional stimuli or intervention. Central to this peculiar biphasic response, which has not been observed with other stimuli to date, is the role of second messenger calcium and cyclic adenosine monophosphate (cAMP) signalling. We show that intracellular Ca2+, modulated by the high frequency excitation, is responsible for activating reorganisation of the actin cytoskeleton in the barrier recovery phase, in which circumferential actin bundles are formed to stabilise the adherens junctions via a cAMP-mediated Epac1–Rap1 pathway. Despite the short-duration stimulation (8 min), the approximate 4-fold enhancement in the transendothelial electrical resistance (TEER) of endothelial cells from different tissue sources, and the corresponding reduction in paracellular permeability, was found to persist over hours. The effect can further be extended through multiple treatments without resulting in hyperpermeabilisation of the barrier, as found with prolonged use of chemical stimuli, through which only 1.1- to 1.2-fold improvement in TEER has been reported. Such an ability to regulate and enhance endothelial barrier capacity is particularly useful in the development of in vitro barrier models that more closely resemble their in vivo counterparts.

Pore structure, thermal insulation and compressive property of ZrO2 nanofiber aerogels with carbon junction fabricated by freeze drying

ZrO2 nanofiber aerogels with carbon as fiber junction were fabricated by freeze drying. The effects of resorcinol-formaldehyde (RF) content and fiber content on the pore structure, thermal property and compressive property of ZrO2/C nanofiber aerogels were systematically investigated. ZrO2/C nanofiber aerogels have ultra-high porosity above 99.4%, and possess hierarchical pore structure with honeycomb pores in the micro-scale and minor pores in the nano-scale. Both RF content and fiber content have effects on the porosity, thermal conductivity and plateau stress of ZrO2/C nanofiber aerogels. Thermal conductivity is in the range of 0.0332–0.036 W·m−1·K−1. With the increase in RF content or fiber content, both thermal conductivity and plateau stress increase. The thermal transfer mode and compressive deformation mode were analyzed. Fiber junctions play a significant role during the thermal transfer and compression of ZrO2/C nanofiber aerogels.

Fabric-inspired thermoelectric two-dimensional imaging array based on carbon nanotube

A thermal imaging array can be a convenient tool for health monitoring and security applications. In this work, a two-dimensional wearable thermal imaging sensor array design comprised of the carbon nanotube (CNT) harnessing thermoelectric effect is proposed. The proposed sensor device was constructed of an array of p-type CNT fibers that are woven across another array of n-type CNT fibers in the similar manner fibers that are woven in textile fabric. Electromagnetic (EM) wave emitted from the subject of detection increases the temperature of certain array nodes of the sensor device, which causes voltage differences between different p–n fiber junctions. Mapping the voltages of all the p–n junctions, thermal images of the subject can be obtained. Though there is a trade-off between responsivity and detection resolution, our proposed sensor can provide a responsivity of 57 V/W for a nanowatt range EM power source with submicrometer level detection resolution according to our calculation. Moreover, we theoretically investigated the effect of the junction distance in the sensor and the size of the hotspot on the resultant thermoelectric voltage.

Simple Strategies for Enhancement of the Strength of Lignin‐Based Nanofibrous Aerogels

AbstractSolvent fractionated lignin and cellulose nanocrystals (CNCs) are used to create highly resilient nanofiber‐based aerogel materials. Two fractions of softwood kraft lignin (SKL) are combined and subsequently electrospun into nanofibers composed of 99% lignin. Additionally, 5 wt.% of CNCs is added into the fiber, based on the solid lignin weight, to enhance the physical properties of the nanofiber materials. The manufacturing process involves dispersing the fibers in water followed by freeze‐drying and subsequent heat treatment. The heat treatment process, with carefully chosen blends of fractionated lignin with specific glass transition temperatures, provides an initial thermoplastic behavior that results in the physical cross‐linking of entangled fibers upon heat treatment. This tailored morphology shows four times higher compressive strength compared to lignin nanofiber materials that only contain high molecular weight fractions. Moreover, CNC is a critical additive that helps maintain fiber geometry by reducing significant softening of lignin under elevated temperatures. Therefore, the fibers with CNC additives ensure the 3D shape after heat treatment, resulting in enhanced physical connections at fiber junctions. As a result, lignin/CNC nanofibers are transformed into 3D structured, lightweight materials that can undergo near full recovery after repeated compressive strain matching the performance of some carbonized analogs.

Electromyography of the muscle spindle

In needle electromyography, there are two spontaneous waveforms, miniature end plate potentials and “end plate spikes”, appearing usually together. Miniature end plate potentials are local, non-propagating postsynaptic waves, caused by spontaneous exocytosis of acetylcholine in the neuromuscular junction. The prevailing hypothesis states that “end plate spikes” are propagated postsynaptic action potentials of muscle fibers, caused by presynaptic irritation of the motor nerve or nerve terminal. Using several small concentric needle electrodes in parallel with the muscle fibers, most “end plate spikes” are strictly local or propagating for 2–4 mm. At the end plate zone, there are miniature end plate potentials without “end plate spikes”. Local “end plate spikes” are junctional potentials of intrafusal gamma neuromuscular junctions of the nuclear bag fibers, and propagated “end plate spikes” are potentials of nuclear chain muscle fibers of muscle spindles. Miniature end plate potentials without “end plate spikes” at the end plate zone derive from alpha neuromuscular junctions. These findings contrast with the prevailing hypothesis. The history of observations and different hypotheses of the origin of end plate spikes are described.

High-Voltage Wave Induced a Unique Structured Percolation Network with a Negative Gauge Factor.

Nanocomposite percolation networks have attracted increasing attention in the field of wearable devices. Generally, the large junction resistance caused by the small contact area in the percolation network is considered as the bottleneck in preparing high-performance electronics. In such electronics, an applied strain will lead to deformation on the fiber junction, subsequently increasing the sheet resistance. However, taking advantage of the dominant role of the contact resistance in the percolation network, the overall resistance of the network can be controlled by skillfully adjusting the contact area. Here, we designed a combined gold-polycaprolactone (Au-PCL) network with a unique buckling net structure. When the thickness of the gold nanolayer is 50 nm, the network shows typical percolation behavior with high transparency (93%), good conductivity (20 Ω/sq), and good ductility. Moreover, the networks show a unique positive relationship between the conductivity and strain due to the variation of contact resistance. By designing different waving angles, the network can be used as a dynamic strain sensor with a tunable gauge factor ranging from -0.8 to -1.8. Overall, these highly stretchable and transparent Au-PCL networks show promising applications in the field of high-performance electronic and optoelectronic nanodevices.

Identification of Hub Genes Associated with Progression and Prognosis of Bladder Cancer by Integrated Bioinformatics Analysis.

Bladder cancer (BLCA) is an extremely common carcinoma of the urinary system that has a high incidence of relapse. Although intensive studies have investigated its pathology in the past decades, there are significant knowledge gaps regarding the characterization of the molecular processes underlying the progression of disease and consequently its prognosis. The purpose of current research was to identify significant genes that could serve as prognostic and progression biomarkers. Gene expression profiles were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. Differential gene expression analysis (DGEA) and weighted gene co-expression network analysis (WGCNA) were conducted to recognize differential co-expression genes. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed to explore gene function. Moreover, protein-protein interactions (PPI) network, overall survival (OS) and disease-free survival (DFS) were used to identify survival-related hub genes. Additionally, associations between these gene's expression and clinical parameters were determined. Finally, the Human Protein Atlas (HPA) database and qRT-PCR were used to validate gene's expression. About 124 differential co-expression genes were identified. These genes were mainly enriched in muscle system process and muscle contraction (biological process, BP), contractile fiber, myofibril, sarcomere, focal adhesion and cell-substrate junction (cellular component, CC) and actin binding (molecular function, MF) in GO enrichment analysis, while enriched in vascular smooth muscle contraction, focal adhesion, cardiac muscle contraction, hypertrophic cardiomyopathy, dilated cardiomyopathy and regulation of actin cytoskeleton in KEGG analysis. Furthermore, five survival-related hub genes (MYH11, ACTA2, CALD1, TPM1, MYLK) were identified via OS and DFS. In addition, these survival-related gene's expression was correlated with grade, stage and TNM stage. Finally, all survival-related hub genes were determined to be down-regulated in BLCA tissues by qRT-PCR and HPA databases. Our current study verified five new key genes in BLCA, which may participate in the prognosis and progression and serve as novel biomarkers of BLCA.

Bariatric surgery induces morphological changes in the extensor digitorum longus muscle in the offspring of obese rats

IntroductionThe effects of the maternal nutritional environment on the growth and metabolism of the offspring, and its impacts on health in adult life are defined as metabolic programming. Thus, the objective of this study was to evaluate the effects of Roux-en-Y gastric bypass (RYGB) on the morphology of muscle fiber and neuromuscular junction (NMJ) of the offspring of rats submitted to RYGB. MethodsThree-week-old Wistar rats were separated into two groups: 1) CAF SHAM which received a cafeteria diet and was submitted to a sham operation and 2) CAF RYGB, which received a cafeteria diet and was submitted to RYGB. The first generation (F1) offspring (male) was named according to the treatment of mothers as CAF SHAM-F1 and CAF RYGB-F1 and received a standard diet after weaning. At 17 weeks, the animals were euthanized, and the extensor digitorum longus muscle (EDL) was collected and processed in light microscopy and transmission electron microscopy for morphological and morphometric analysis. ResultsThe CAF RYGB-F1 group showed a reduction in the weight of the EDL muscle and also a reduction in the area of type I, IIa and IIb fibers and a nucleus/fiber ratio. This same group also showed an increase in the capillary density and myofibrillar disorganization and in the Z-line, as well as a reduction in the area of the NMJs. ConclusionThe RYGB surgery in mothers produced morphological changes in the skeletal striated muscles of the offspring.

In the human, true myocutaneous junctions of skeletal muscle fibers are limited to the face.

Within the panniculus carnosus‐associated skeletal muscles in the human, the palmaris brevis and the platysma showed myotendinous/myofascial junctions with clear distance to the corium and the specific connection collagen type XXII. The orbicularis oris muscle, in contrast, contained bundles of striated muscle fibers reaching the corium at two distinct levels: the predominant inner ending was connected to the elastic network of the inner corium and the outer ending was within the more superficial collagen network. At both locations, the striated muscle fibers showed brush‐like cytoplasmic protrusions connecting a network which was not oriented toward the muscle fibers. Collagen type XXII was not present.

Preparation of free-standing flexible conductive silver submicron fiber network by direct electrospinning

This paper presents free-standing flexible conductive silver submicron fiber networks prepared by electrospinning. Fused junctions of silver fibers naturally form by heat process and result in high conductivity of silver fiber networks. Transparent electrodes made of electrospun silver fiber networks can achieve sheet resistance of 3 Ωsq−1 at 78% transparency and show excellent flexibility, of which the sheet resistance increases by only 50% after 500 bending cycles with a bending radius of 0.8 mm. The study provides a way to fabricate low-cost flexible conductive silver fiber networks that can be used in displays and solar cells.

Fracture and damage model of composite ceramics

It is of great significance to study the damage and fracture mechanism of trigonometrically symmetric eutectic multiphase ceramics with excellent mechanical properties at room temperature and high temperature. According to the microstructure characteristics of inner triangular symmetric eutectic in multiphase ceramics, a two-scale cell model containing triangular symmetric eutectic was established. The fracture stress of cohesive bond in eutectic was calculated by considering the conditions of cohesive bond fracture at interface phase and fiber junction. The damage variable was introduced and combined with cohesive bond fracture stress to establish the microcosmic damage fracture stress model of eutectic Based on the Dugdale Barenblatt model, the damage localization band model is established by introducing the micro damage fracture stress as the residual strength. It is found that with the increase of fiber volume fraction, the strong confinement of interface phase is destroyed, the residual strength decreases and the length of damage localization band increases with the increase of fiber volume fraction. Reducing the damage degree and selecting the appropriate fiber volume content can increase the fracture stress of eutectic, and then reduce the length of damage localization band, increase the threshold value of crack instability propagation, and enhance the material strength.