Fibrous Shell Research Articles

Experimental and numerical study of specific bending behavior of tufted multilayered reinforcements and effects of tufting density

The tufting technology enhances the delamination and impact resistance of composites. The presence of tufting yarns leads to a modification of the structure of the fabric, which affects the bending behavior of tufted reinforcements. Tufted reinforcements experience significant slippage during bending, challenging classical plate and shell theories. Therefore, the bending behavior of tufted reinforcement is investigated and a specific fibrous shell approach is proposed, assuming quasi-inextensibility of fibers and potential slippage between them. The influence of tufting yarns on the bending behavior is integrated into the constitutive model. The experimental results show that the bending stiffness of reinforcements can be increased by tufting density. The simulations exhibit a good agreement with experiments, demonstrating that the proposed approach can accurately capture not only the bending deflections of tufted reinforcements, but also the rotation of material direction indicators. Using the proposed numerical method, the prediction accuracy for deflection and rotation angle of tufted reinforcements reaches 90% in cantilever bending tests and 85% in three-point bending tests. These novel insights can deepen the understanding of the bending behavior of tufted reinforcements and be an asset of the developing numerical model for the forming simulation.

Significant size change during bacterial cellulose capsule drying

Use of engineered powders, whether by manufacturers or consumers, often requires rapid hydration but is hindered if hydration rates exceed dispersion rates, leading to “fish eyes”. More work is needed to understand how powder could be engineered to actively contribute to its own dispersion while minimizing the use of additional materials and additives. A recently developed bacterial cellulose microcapsule matrix, with good mechanical integrity but minimal mass usage, exhibits remarkable deformability owing to its fibrous shell structure. When dried into powder, the cellulose microcapsules experience significant deformation of their fibrous shells, changing their diameter by orders of magnitude. We demonstrate a capsule shape recovery mechanism by coating the cellulose fibers, which damps fiber interactions. The results demonstrate that drying microfibrous cellulose microcapsules can expand the range of encapsulation modes available and greatly reduce the mass needed to provide efficient powder rehydration.

Hollow TiO2@Fe2O3 nanofiber additives using template based approach for capture-conversion of polysulfides in Lithium-sulfur batteries

High theoretical capacity (1675 mA h g−1) and energy density (2600 Wh kg−1) in addition to low cost, non-toxicity and natural abundance stimulates the exploration of sulfur as a potential cathode material. However, serious capacity fade and poor reaction kinetics leads to untimely failure which prevents the practical commodification of these batteries. Here, a simple and versatile electrospinning technique has been employed to prepare a polymeric template to fabricate hollow metal oxide@metal oxide nanofibers. The hollow fibrous shell with large specific surface area is incorporated as an anchoring material comprising of distinct crystalline phases separated by amorphous domains. Meanwhile, the encapsulated metal oxide nanoparticles ensure efficient conversion of soluble polysulfides thereby, promoting the reaction kinetics and avoiding any surface passivation of anchoring material. The LSB cell with 5 % TiO2@Fe2O3 nanofiber additives delivers impressively in the rate capability test with stable capacities of 620 and 480 mA h g−1 at 1C and 2C rate, respectively. Moreover, an excellent cycling performance is attained with a fade rate of 0.092 % per cycle over 500 cycles at 0.5C-rate. The findings of this work shall provide a pathway for facile preparation of functional metal oxide composites for simultaneous trapping and conversion of polysulfide species in sulfur batteries.

Influence of in-plane bending behaviour on textile composite reinforcement forming

The deformation of textile composite reinforcement is influenced by its fibrous composition. In-plane bending behaviour is an inherent aspect of textile reinforcement, yet it is frequently overlooked. The paper elucidates the significant influence of in-plane bending behaviour on fibre orientation during forming process and emphasizes the necessity of accounting for in-plane bending virtual work to prevent non-physical deformation mode. To this purpose in-plane bending calculation is implemented into a fibrous shell finite element by using the neighbouring elements method. Numerical spurious mode involving in-plane shear is avoided due to the new approach. Finally, the model is validated by comparing with composite reinforcement draping experiments: fibre orientations and distributions of shear angles are simulated in good agreement with experiments and give better results than the simulations neglecting the in-plane bending behaviour.

A coaxial electrospun mat coupled with piezoelectric stimulation and atorvastatin for rapid vascularized bone regeneration.

The repair of critical bone defects caused by various clinical conditions needs to be addressed urgently, and the regeneration of large bone defects depends on early vascularization. Therefore, enhanced vascularization of artificial bone grafts may be a promising strategy for the regeneration of critical-sized bone defects. Taking into account the importance of rapid angiogenesis during bone repair and the potential of piezoelectric stimulation in promoting bone regeneration, novel coaxial electrospun mats coupled with piezoelectric materials and angiogenic drugs were fabricated in this study using coaxial electrospinning technology, with a shell layer loaded with atorvastatin (AVT) and a core layer loaded with zinc oxide (ZnO). AVT was used as an angiogenesis inducer, and piezoelectric stimulation generated by the zinc oxide was used as an osteogenesis enhancer. The multifunctional mats were characterized in terms of morphology, core-shell structure, piezoelectric properties, drug release, and mechanical properties, and their osteogenic and angiogenic capabilities were validated in vivo and ex vivo. The results revealed that the coaxial electrospun mats exhibit a porous surface morphology and nanofibers with a core-shell structure, and the piezoelectricity of the mats improved with increasing ZnO content. Excellent biocompatibility, hydrophilicity and cell adhesion were observed in the multifunctional mats. Early and rapid release of AVT in the fibrous shell layer of the mat promoted angiogenesis in human umbilical vascular endothelial cells (HUVECs), whereas ZnO in the fibrous core layer harvested bioenergy and converted it into electrical energy to enhance osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs), and both modalities synergistically promoted osteogenesis and angiogenesis. Furthermore, optimal bone regeneration was achieved in a model of critical bone defects in the rat mandible. This osteogenesis-promoting effect was induced by electrical stimulation via activation of the calcium signaling pathway. This multifunctional mat coupling piezoelectric stimulation and atorvastatin promotes angiogenesis and bone regeneration, and shows great potential in the treatment of large bone defects.

Conductive nerve conduit with piezoelectric properties for enhanced PC12 differentiation

Restoration of nerve tissue remains highly challenging, mainly due to the limited regeneration capacity of the nervous system and the development of fibrosis. This limitation necessitates designing new nerve guidance channel to promote nerve repairing. In this study, we developed a novel core/shell conduit to induce PC12 differentiation. Co-electrospinning method was utilized to produce a fibrous shell containing polycaprolactone/polyvinylidene fluoride PCL/PVDF, gelatin and polyaniline/graphene (PAG) nanocomposite. The core section of the conduit was filled with chitosan–gelatin hydrogel containing PAG and ZnO nanoparticles. Such conduit shows antibacterial activity, electrical conductivity and piezoelectric property. The effect of such engineered conduit on PC12 differentiation was investigated by analyzing differentiation markers Nestin and microtubule-associated protein 2 (MAP2) through immunocytochemistry and PCR-RT techniques. The result revealed that such conduit could significantly induce Nestin and MAP2 gene expression in the PC12 cells and, thus, it is a viable option for effective cell differentiation and nerve regeneration.

Magnetic dendritic KCC-1 nanosphere-supported cobalt composite as a separable catalyst for hydrogen generation from NaBH4 hydrolysis

The introduction of magnetism into a catalyst can greatly optimize its separation performance. In the present work, a kind of magnetically separable catalysts for promoting NaBH4 hydrolysis have been fabricated by anchoring cobalt nanoparticles on magnetic dendritic KCC-1 nanospheres composed of magnetic Fe3O4 core and fibrous shell. The fabricated catalysts were characterized with various characterization methods, including absorption spectroscopy (AAS), scanning electron microscopy (SEM), high-resolution transmission electronic microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), and Fourier transform infrared (FT-IR), etc. This kind of catalysts exhibit high catalytic activity for promoting the hydrolysis of NaBH4 under alkaline conditions, giving a hydrogen generation rate and activation energy of 3.83 L min−1 gCo−1 (30 °C) and 53.63 kJ mol−1, respectively. After used for 5 cycles, the catalyst showed 36.5% catalytic activity reserved. Most importantly, the magnetism of the catalyst made it easily separated and recycled from the solution after the reaction completed. The development of this kind of catalysts could provide a promising option for catalyzing NaBH4 hydrolysis for portable hydrogen production from.

Mass Transfer from a Drop in Fall into the Fluid Thickness

High-speed videorecording is used to trace the fine structure evolution in the case of freely falling drop matter propagation beneath the deformed surface of a fluid, initially at rest. The coalescence of a water drop with ammonium rhodanide solution and drops of sodium chloride solution, sodium carbonate, and ink with water is studied. In the initial stage of the coalescence process occurring in the impact regime with rapid cavity formation the drop loses the continuity. Short thin jetlets penetrating the cavity bottom are visualized for the first time. The earlier-observed drop disintegration into thin fibers that form linear or reticular structures on the cavity and crown surfaces is confirmed.The jetlets that contain the drop matter merge gradually and form an intermediate fibrous layer embracing the cavity; this layer possesses a well-defined outer boundary. As the cavity enlarges, the intermediate layer homogenizes and becomes thinner. Further on, in the process of cavity collapse new fiber groups are formed in the target fluid; they penetrate the cavity boundary beneath the grid nodes. In the experiments performed the fibrous layer embracing the primary cavity was observable, when a fluid of greater density (ink, sodium carbonate, or sodium chloride solution drops) intruded into a less dense medium (water) or when a fluid of smaller density (water droplets) was introducedinto a heavier fluid (ammonium rhodanide solution). The fibrous shell of the primary cavity becomes thicker with increase in the drop velocity.

The fibrous shell approach for the simulation of composite draping with a relevant orientation of the normals

Simulations of composite reinforcements draping use shell finite elements for which the bending behaviour is very particular. The fibrous composition of the reinforcements significantly reduces the bending stiffness compared to classical materials. Moreover, the kinematics of the deformation is strongly modified and does not follow classical theories such as Kirchhoff's. The objective of this paper is to show that a fibrous shell approach based on the quasi-inextensibility of the fibres makes it possible to correctly model the deformation during forming. In particular, the rotation of the material normal is simulated in good agreement with the forming experiments, which is not the case for the alternative approaches that have been proposed for the draping of composites.

New Pliensbachian rhynchonellide (Brachiopoda) from Livari, (Rumija Mountain, Montenegro): the taxonomic implications of microstructure to disentangle cases of homeomorphism

ABSTRACT An interesting case of close external similarity (homoeomorphy) is revealed by the study of an Early Jurassic rhynchonellide brachiopod from Livari, Rumija Mountain, southern Montenegro. Shell microstructure was used as the primary diagnostic tool, applied before serial sectioning to study internal characters. Sepkoskirhynchia sphaerica gen. et sp. nov. is erected based on the presence of coarse fibrous shell microstructure and hamiform crura. Because of these primary diagnostic characters, the new genus is placed in the rhynchonellide family Basiliolidae. The shell microstructure of the new taxon is characterised by a differentiated secondary layer of coarse fibrous type. The fibres are rhombic or subquadrate in cross-section, in the external sublayer they are 55–60 μm wide and 40–50 μm thick, internally other sublayers are thinner with fibres 35–40 μm wide and 20–25 μm thick. The main character that distinguishes the new genus is that the secondary layer is differentiated into several sublayers, while in externally homoeomorphic Soaresirhynchia it is built of a single layer. The new taxon was found in the brachiopod and crinoidal limestones from the periplatform facies of the Dinaric Carbonate Platform.

Investigation on thermal properties of tamarind shell particles reinforced hybrid polymer matrix composites

The structural features of the by-products from chicken poultry encourage their better use over dumping or incineration, and polymer composite materials constitute a zone for direct use in small treatment amounts. The polymer composites have been prepared, and their thermal stability tested with chicken feather fibres in open fibrous shell paws and nano tamarind coating powder. Heating rates were of 150 °C/min from 0 to 800 °C, and characterization of thermogravimetry and thermal differential analysis was performed. The results show three phases of thermal decomposition: moisture evaporation below 200 °C, the decomposition of the chicken fibre between 150 °C and 300 °C and the final decomposition of the matrix below 550 °C. The differences in thermal stability were insignificant when the content of chicken feather fibres increased, and the content of nano tamarind shell particles decreased.

Polyaniline-coated core-shell silica microspheres-based dispersive-solid phase extraction for detection of benzophenone-type UV filters in environmental water samples

Polyaniline-modified core-shell mesoporous silica (CSMS@PANI) nanocomposite microspheres are synthesized as adsorbent in dispersion-solid phase extraction (d-SPE) for enrichment and purification of benzophenone-type UV filters. The synthesized CSMS@PANI nanocomposite microspheres exhibit large specific surface area (33.45 m2/g) and uniform fibrous shell (microsphere diameter of 1.3 μm, outer silica shell thickness of 120 nm, pore diameter of 12.04 nm), which can greatly improve the extraction efficiency of the samples. Combining CSMS@PANI based d-SPE with sheathless capillary electrophoresis-tandem mass spectrometry for detection, we can achieve sensitive determination of six benzophenone-type UV filters with the detection limit of 0.6 pg/mL-0.2 ng/mL and the enrichment factors of 470-660. The method is successfully applied for ultrasensitive detection of trace amount benzophenone-type UV filters in environment water samples. It is indicated that the method has the advantages of rapid and efficient enrichment, high sensitivity, and excellent repeatability. Our study extends the application of core-shell mesoporous silica materials and would be of value for pretreatment of trace-amount and complex real samples.

Development of collagen-poly(caprolactone)-based core-shell scaffolds supplemented with proteoglycans and glycosaminoglycans for ligament repair

Core-shell scaffolds offer a promising regenerative solution to debilitating injuries to anterior cruciate ligament (ACL) thanks to a unique biphasic structure. Nevertheless, current core-shell designs are impaired by an imbalance between permeability, biochemical and mechanical cues. This study aimed to address this issue by creating a porous core-shell construct which favors cell infiltration and matrix production, while providing mechanical stability at the site of injury. The developed core-shell scaffold combines an outer shell of electrospun poly(caprolactone) fibers with a freeze-dried core of type I collagen doped with proteoglycans (biglycan, decorin) or glycosaminoglycans (chondroitin sulphate, dermatan sulphate). The aligned fibrous shell achieved an elastic modulus akin of the human ACL, while the porous collagen core is permeable to human mesenchymal stem cell (hMSC). Doping of the core with the aforementioned biomolecules led to structural and mechanical changes in the pore network. Assessment of cellular metabolic activity and scaffold contraction shows that hMSCs actively remodel the matrix at different degrees, depending on the core's doping formulation. Additionally, immunohistochemical staining and mRNA transcript levels show that the collagen-chondroitin sulphate formulation has the highest matrix production activity, while the collagen-decorin formulation featured a matrix production profile more characteristic of the undamaged tissue. Together, this demonstrates that scaffold doping with target biomolecules leads to distinct levels of cell-mediated matrix remodeling. Overall, this work resulted in the development of a versatile and robust platform with a combination of mechanical and biochemical features that have a significant potential in promoting the repair process of ACL tissue.

Synthesis and adsorption behavior study of magnetic fibrous mesoporous silica

Abstract In this study, phenylboronic acid-modified magnetic fibrous mesoporous silica (MFMS-P) was successfully synthesized by an improved one-step oil–water biphase stratification coating strategy using a precise velocity control device. The transmission electron microscopy images showed particles composed of a Fe3O4 core (150–200 nm), nonporous silica interlayer (50 nm), and a fibrous shell (110 nm), exhibiting radial-like direct channels and ideal pore size (12.72–13.58 nm). The adsorption behavior, including the adsorption model, adsorption kinetics data and thermodynamic parameters, was systematically investigated. The kinetic study indicated that MFMS-P exhibits high adsorption capacity (293.03 μmol g−1) and rapid adsorption equilibrium for catechol (reached within 10 min). The adsorption rate (k = 0.0613 g (mg min) −1) for catechol is much higher owing to the suitable pore structure of the present material, which greatly facilitates the target molecules reaching the active sites in a more efficient manner. All the results demonstrate that this magnetic fibrous-structured mesoporous silica is an excellent separation material for rapid separation applications.

To the estimation of thickness and stiffness of fibrous shell in the zone of the pole hole

When carrying out strength calculations of shells of rotation from fibrous composite materials, it is rather unreliable to assess the behavior of the shell in the zone of the pole hole. This inaccuracy occurs due to the lack of correct algorithms for calculating the thickness and stiffness of the shell in the area under consideration. Using the proposed algorithm, the analysis of changes in the stiffness of the shell in the zone of the pole hole for different versions is carried out (the formation of the tape, consisting of a different number of bundles) and their comparison with the calculations obtained by previously known methods. The use of the found dependences makes it possible to assess the rational distribution of the wound material in the design and technological implementation of the shell of a fibrous composite material and is especially important in assessing the deformation of the shell in the considered zone of the pole hole, the value of which practically determines the cyclic strength of the material of the liner.

Research into the influence of vertical drainage elements on the operational efficiency of rapid filters

To improve the efficiency of removal of suspended solids at rapid filters, we designed improved structure of the device. The improvement is based on the application, simultaneously with a granular filter layer, of vertical drainage elements with porous fibrous shells. Such a solution makes it possible to shift part of the load to the shells of drainage elements, reduce colmatation and head losses in a granular filter layer, as well as to more evenly distribute contaminants along its height. This increases the duration of operation of the filter under filtering mode and brings down the cost of regeneration of a filter layer. A filtration equation was derived to describe parallel filtration of a low-concentrated suspension through a granular medium and a fibrous medium. The mathematical model also includes equations of mass transfer, mass exchange and dependences to account for the impact of colmatation and parameters of filtering media. For a granular filter layer, we considered filtering with a gradual blocking of pores; for a porous shell ‒ the formation of a sediment layer at its surface. Using a mathematical model, we conducted numerical experiments. The following significant parameters for the filter with improved design were determined: equivalent diameter of particles in a filter layer, working height of the vertical drainage element, duration of washing a porous fibrous shell. We give examples of calculations for determining the values of basic parameters at which the effectiveness of application of vertical drainage elements is maximal

Dendritic core-shell silica spheres with large pore size for separation of biomolecules

Monodispersed core-shell silica spheres with fibrous shell structure and tunable pore size were prepared by using a one-pot oil-water biphase method. The pore size could be tuned from 7 nm to 37 nm by using organic solvents with different polarities as oil phase. The spheres synthesized by using benzene as organic solvent had the maximum pore size of 37 nm and possessed a surface area of 61 m2 g−1. The obtained wide pore core-shell silica spheres were applied for rapidly separating small molecules, peptides, small proteins, and large proteins with molecular weight up to 200 kDa. Since the pore size of the core-shell silica spheres was sufficiently large for the free access of all the solutes, sharp and symmetric peaks were obtained. The separation performance was as high as 264,531 plates m−1 for fluorene. The great efficient separation demonstrates that the wide pore core-shell silica spheres have a great potential for rapid analysis of both small and large solutes with high performance liquid chromatography.

Comprehensive assessment of the content of polycyclic aromatic hydrocarbons and dependence of their accumulation in meat products

Dependences of the quantity of polycyclic aromatic hydrocarbons (PAH) on the conditions for the formation of components of smoke compositions, the type of wood, the formulation, the technology of production, and the type of packaging material have been studied. An increase in temperature from 450 to 700 °C lead to a 2-3-fold increase in the amount of PAH in meat products. It has been established that the use of a polyamide coating reduced the total carcinogenicity of sausages by 2.0-3.7 fold compared with protein and natural shells, which in terms of PAH accumulation were the most dangerous. Fibrous shell was able to provide a reduction in PAH level in the product up to 40% compared to natural one. The permeability of the fat fraction of the product for PAH was up to 10 fold higher than that of proteins and carbohydrates. The data obtained made it possible to determine the safety criteria for smoked meat products, taking into account the potential carcinogenic hazard of each PAH. The optimal indicators of the presence of PAH in the product are 8 PAH (benz[a]pyrene, chrysene, benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[g,h,i]perylene, dibenz[a,h]anthracene, indeno[1,2,3-c,d] pyrene). The PAH exposure on the human body has been determined under the constant consumption of smoked meat products. The prospective use of barrier protection technologies, substances possessing antiradical activity, and protective films to reduce residual PAH content has been proved. The results of the studies showed a 5-fold decrease in the total amount of PAH when using films impregnated with fat-containing micro anemulsion of vegetable or animal fat. The effect increased when meat was marinateв in a 9% solution of acetic acid or 3% solution of ascorbic acid.

Synthesis of core-shell silica spheres with tunable pore diameters for HPLC

Core-shell silica particles with fibrous shell structure and tunable pore size were prepared by using a dul-template method. The pore size of the core-shell silica particles was affected greatly by the amount of octadecylamine, which as used as cosurfactant. The pore size could be enlarged from 7.1nm to 22.3nm while keeping the unique fibrous shell structure. After derivatized with C18, the separation performances of these particles with a wider pore size were investigated. The column efficiency was as high as 219,789 plates m−1 for dimethylnaphthalene. Baseline separation of proteins ranging in size from 12 to 66kD was achieved within 5min. The separation results demonstrate that the synthesized core-shell silica particles would be a promising packing material in the rapid and high-resolution separation of both small solutes and macromolecules.

A shell formulation for fibrous reinforcement forming simulations

The fibrous nature of continuous fiber textile composite reinforcements strongly modifies their mechanical behavior, in particular for bending. The basic assumptions of classical plate and shell theories are not verified by these materials during a deformation because of the slippage between fibers. However, simulations of reinforcement forming generally use shell finite elements. A shell formulation is proposed for the forming of continuous fiber reinforcements. The large tensile stiffness leads to the quasi inextensibility in the fiber directions. The fiber bending stiffness determines the curvature of the reinforcement. The calculation of tensile and bending virtual works are based on the precise geometry of the single fiber. A simple way to consider friction between fibers is to take it into account in the flexion bending. Simulations and experiments are compared for different reinforcements. It is shown that the proposed fibrous shell approach not only correctly simulates the deflections but also the rotations of the through thickness material vectors. This is particularly interesting in the case of thick interlock reinforcements.