Elastic Core Research Articles

A Conductive Binder Based on Mesoscopic Interpenetration with Polysulfides Capturing Skeleton and Redox Intermediates Network for Lithium Sulfur Batteries

AbstractThe practical application of lithium‐sulfur batteries with high theoretical energy density and readily available cathode active materials is hampered by problems such as sulfur insulation, dramatic volume changes, and polysulfide shuttling. The targeted development of novel binders is the most industrialized solution to the problem of sulfur cathodes. Herein, an aqueous conductive emulsion binder with the sulfonate‐containing hard elastic copolymer core and the conjugate polymer shell, which is capable of forming a bicontinuous mesoscopic interpenetrating polymer network, is synthesized and investigated. Not only can the elastic skeleton formed by the copolymer bind the active substance under drastic volume changes, but also the rich ester and cyanide groups in it can effectively capture lithium polysulfide. Meanwhile, the conducting skeleton consisting of poly(3,4‐ethylenedioxythiophene) both provides the additional charge conduction pathways and acts as the redox intermediates, significantly accelerating the kinetic process of lithium polysulfide conversion. Based on the synergistic effect of the above mechanisms, the use of the prepared binder on the sulfur carbon cathode significantly improves the rate performance and cycle stability of lithium sulfur batteries.

A Conductive Binder Based on Mesoscopic Interpenetration with Polysulfides Capturing Skeleton and Redox Intermediates Network for Lithium Sulfur Batteries.

The practical application of lithium-sulfur batteries with high theoretical energy density and readily available cathode active materials is hampered by problems such as sulfur insulation, dramatic volume changes, and polysulfide shuttling. The targeted development of novel binders is the most industrialized solution to the problem of sulfur cathodes. Herein, an aqueous conductive emulsion binder with the sulfonate-containing hard elastic copolymer core and the conjugate polymer shell, which is capable of forming a bicontinuous mesoscopic interpenetrating polymer network, is synthesized and investigated. Not only can the elastic skeleton formed by the copolymer bind the active substance under drastic volume changes, but also the rich ester and cyanide groups in it can effectively capture lithium polysulfide. Meanwhile, the conducting skeleton consisting of poly(3,4-ethylenedioxythiophene) both provides the additional charge conduction pathways and acts as the redox intermediates, significantly accelerating the kinetic process of lithium polysulfide conversion. Based on the synergistic effect of the above mechanisms, the use of the prepared binder on the sulfur carbon cathode significantly improves the rate performance and cycle stability of lithium sulfur batteries.

Detection of Stress Distribution in Surrounding Rock of Coal Seam Roadway Based on Charge Induction Principle

Rock burst is a worldwide prevention and control problem, and the main reason for its occurrence is the concentration of stress in the surrounding rock of the coal roadway. Therefore, it is of great significance to realize the rapid and accurate detection of the stress distribution in the surrounding rock of the roadway for the prevention and control of rock burst. Based on the principle of charge induction, this paper adopts a research method combining theoretical analysis and indoor and field tests to carry out a study on the charge induction detection of stress distribution of surrounding rock in coal seam roadways using the self-developed coal rock charge induction monitor. A theoretical analysis of the charge induction intensity in relation to the stress level is carried out. Indoor tests on the law of charge induction for graded loading of large sized coal samples are carried out. Field detection tests of the charge induction law at different drilling depths on the solid coal side and the large coal pillar side of the coal seam roadway are carried out. The results show a positive correlation between the charge signal intensity and the stress magnitude. The induced charge of coal samples has a tendency to increase with the increase in graded loading stress level. The magnitude of the induced charge can reflect the stress level of the coal body. On the solid coal side, the induced charge has a tendency of increasing and then decreasing with the increase in detection depth. The final results are in good agreement with the results of the drill chip method, which better reflects the distribution of the lateral support pressure of the roadway. On the side of the large coal pillar, the induced charge has a tendency to increase, then decrease, and then increase with the increase in probing depth, which is in good agreement with the distribution of lateral support pressure formed in the elastic core area of the large coal pillar. Therefore, the charge induction technology can be used as a fast, non-contact detection means for the partitioning and stress distribution of the roadway enclosure, which can provide guidance for the target prevention and controlling rock burst and for designing roadway support.

Highly sensitive and stretchable fiber strain sensors based on ITO NPs/CNTs composite

Flexible and multifunctional sensors are in demand in various fields, but achieving excellent sensitivity and an extensive operational range poses a challenge. Here, we developed a flexible strain sensor using a cost-effective dip-coating method, incorporating microcracked synergistic indium tin oxide nanoparticles (ITO NPs) and carbon nanotubes (CNTs) in a conductive layer. Utilizing an elastic rubber core string as the stretchable substrate and Thermoplastic polyurethane (TPU) as an interfacial modifier, we established connectivity between the substrate and conductive layer. After encapsulation with polydimethylsiloxane, the ITO NPs/CNTs/rubber fiber (ICRF) strain sensor was fabricated. This sensor demonstrates a broad sensing range (0 ∼ 300 %), remarkable sensitivity (GF=1033.57), swift response/recovery times (174.55 ms/180.27 ms), and exceptional durability and stability (>2000 cycles). Moreover, it proves effective for human motion detection, underscoring its potential in flexible and wearable devices. Finally, precise responses of the mechanical claw’s posture and grasping demonstrate its potential applications across multiple fields.

A mechanical analogue of electromagnetic induction for waves in a chiral elastic structure

Classical Faraday’s law on electromagnetic induction states that a change of magnetic field through a coil wire induces a current in the wire. A mechanical analogue of the Lorentz force, induced by a magnetic field on an electric charge, is the gyroscopic force. Here, we demonstrate a mechanical analogy with a chiral elastic waveguide subjected to gyroscopic forcing. We study waves in an infinite mass-spring ‘gyrocore helix’, which consists of a helix and a central line (gyroscopic elastic core). The helicoidal geometric chirality is considered in conjunction with a physical chirality, induced by gyroscopic forces. It is shown that the interplay between these two chiral inputs leads to the breaking of symmetry of the associated dispersion diagram, resulting in a unidirectional waveform with the direction of propagation being tunable through the gyricity.

Magneto-electro-mechanical responses of smart sensor/actuator for detection the information in football’s ball

A small-scale formulation is developed based on modified couple stress theory (MCST) for shear deformation analysis of piezomagnetic nano-panels. This theory employs the couple stress and symmetric curvature tensors to include the length scale parameter in the micro scale to capture size-dependency. The micro-panel is fabricated from an elastic core integrated with two piezoelectric/piezomagnetic face sheets subjected to initial electromagnetic loads. Using the principle of virtual work, the static governing equations are derived in terms of radial, axial, and circumferential displacements, axial and circumferential rotations, and electromagnetic potentials. An analytical method is employed to solve the governing equations. The structure is used for detection of the information in the football’s ball with changes of the position of the equipment in the sport. The results are estimated using the proposed model. Effect of important material and geometric parameters such as micro length scale parameter, initial electromagnetic potentials, and some geometric parameters such as length and span angle are also investigated on the bending features such as deformation and rotations components as well as maximum electromagnetic potentials.

Exploring dynamic response in a three-layer dome with non-homogeneous elastic core under a concentrated impact at its apex

Exploring dynamic response in a three-layer dome with non-homogeneous elastic core under a concentrated impact at its apex

Development of dual-core spun yarn using different fiber as a core by hamel twisting (elasto twist) technique and its impact on the denim fabric performance

Textile industries constantly explore innovative methods to increase fabric and yarn properties meeting multiple consumer demands and yarns (dual core) especially those incorporating an elastic core have obtained concentration for their potential in producing fabrics with improved stretch and recovery properties. This study focuses on the manufacturing of yarns (double core) using Hamel Twisting (Elasto twist) techniques utilizing core materials wrapped with 'S' and 'Z' directions such as polytrimethylene terephthalate/polyethylene terephthalate (T400®), PBT (Polybutylene terephthalate), PES (Polyester) and elastane (Lycra®). The yarns are manufactured utilizing an adjusted spinning technique (ring) and the work focuses on core materials wrapped with 'S' and 'Z' direction to the dual-core spun yarns using the Hamel Twisting (Elasto twist) method and also includes the manufacturing of denim fabrics (3/1 ‘Z’ twill) utilizing the developed yarn as weft. The article presents a comprehensive analysis of yarn properties, including unevenness, strength, neps (+200), elongation, thick place (+50), hairiness, and thin place (−50), and subsequently evaluates the fabric properties, such as weight (dry and washed), elasticity %, tensile strength, growth %, tearing strength, stiffness, and shrinkage. The statistical analysis utilizes Two-way ANOVA to examine the significant variations in fabric and yarn characteristics among several core components and their wrapped directions. The findings present an understanding of the performance of yarns (double core) manufactured through the elasto twist method, offering precious insights for applications in multiple textile products, including denim fabrics.

Can resistance training improve throwing performance in handball players? A Systematic review and meta-analysis

BackgroundThrowing is one of the most important movement in handball. Throwing performance is crucial for success in handball.ObjectiveΤo investigate the level of evidence for the effect of resistance training (RT) on throwing performance in handball players.MethodsSystematic searches of Pubmed, Medline complete, Cinahl, Sport Discus and Scopus were undertaken for peer reviewed articles published between 18 March 1995 to 18 March 2023. Randomized, controlled, clinical studies, written in English, aiming to investigate the effect at least one modality of RT on throwing performance (velocity or/and accuracy) in handball players were considered for inclusion in the study. The eligible studies were assessed for methodological quality using the Physical Therapy Evidence Database (PEDRO) scale. The Best Evidence Synthesis (BES) approach was used for synthesizing and reporting the results. Furthermore, the random-effects model was used for the meta-analysis and the Q-statistic was used to test the null hypothesis that all studies in the analysis share a common effect size.ResultsOne hundred ninety-eight studies were identified, of which 30 were included. A total of 727 handball players (males = 388, females = 292) were included. 28 of the 30 studies were rated as high methodological quality studies (PEDRO score > 70%) while the rest of the studies were rated as moderate methodological quality studies (PEDRO score ≤ 60%). The mean effect size for the effectiveness of resistance training (RT) in improving jumping throw, running throw, and standing throw velocity were 1.128 (95% CI 0.457 – 1.798), 1.756 (95% CI 1.111 – 2.400), and 1.098 (95% CI 0.689 – 1.507) correspondingly. Traditional weight training using barbells in mostly compound lifts yielded the most significant and robust results. Other RT modalities such as elastic bands, medicine balls, core training and ballistic training showed no significant results or positive effects due to the limited number of the studies.ConclusionStrong evidence exists only for the effectiveness of RT using barbells in increasing throwing velocity. In contrast, the remaining RT modalities, while yielding positive results, have limited support due to limited number of studies and the high heterogeneity between studies. Furthermore, there is insufficient evidence to support various forms of RT in increasing throw distance. Finally, medicine ball training and elastic band training demonstrated no benefits in improving throwing accuracy.Trial registrationPROSPERO ID: CRD42023393574.

Highly stretchable and strain sensitive MXene/MXene:MWCNTs@TPU fiber with hierarchical conductive layers and porous elastic core structure

Fiber flexible strain sensors have the characteristics of small volume, light weight, good flexibility, easy deformation/recovery, and easy weaving. They can conform to various complex surfaces and endure various deformations, such as twisting and bending. Furthermore, the simple preparation process of fiber sensors lowers the production cost significantly. These features make them promising candidates for applications in motion monitoring, human-machine interface, and flexible intelligent products. However, the low sensitivity and narrow sensing range of existing sensors are still major challenges for their further development. To address these challenges, this paper proposes a MXene/MXene:MWCNTs@TPU fiber sensor, which adopts a two-step pre-stretching strategy to modify the porous TPU fiber surface with MXene and MWCNTs. The graded porous TPU fibers obtained by wet spinning can achieve 805 % stretching, providing a reliable substrate support for the fiber sensor, the combination of multi-dimensional conductive materials and the introduction of cracks and wrinkles enhance the sensitivity 277 and sensing range 510 % of the fiber sensor. The fiber sensor can detect various human motions and gestures by directly attaching to the skin or weaving into textiles, and can also be applied to information encryption transmission, demonstrating its huge potential in human health monitoring, intelligent flexible electronic products and encrypted communication.

A viscoelastic–plastic constitutive model incorporating creep initiation stress for surrounding rock in deep roadways and its practical application

AbstractWith the increasing depth of engineering in rock masses, the issue of significant rheological deformation becomes notably prominent. To accurately characterize the deformation and failure behavior of the surrounding rock near the goaf in deep small coal pillars, we have developed a viscoelastic–plastic constitutive model that takes into account the initial stress associated with creep. This model builds upon an existing viscoelastic–plastic constitutive framework and is implemented numerically using C++ in the FLAC3D. The Oedometer test method is used to check the creep components and the calculated parameter (η/G) ensure convergence of numerical operations. We conducted both pre‐improvement and post‐improvement tests of the constitutive model in a simple numerical analysis of roadways. The enhanced model demonstrates improved accuracy in deviational stress calculations and proves suitable for modeling deep, soft roadways. Furthermore, we applied the improved model to simulate actual working conditions at Zhaozhuang Mine, where mining operations near the working face induce a fracture zone of approximately 3 m in the small coal pillar located at the goaf's edge. The new model closely aligns with the observed results, further validating its suitability for tunneling along the goaf. Tunneling and mining activities result in significant deformation at various locations, including the shoulder socket of the working face, the top angle of the coal pillar, and the bottom angle of the floor. The crushing zone at the working face extends up to 4 m. Rheological effects transform the triangular elastic core, from its original high‐pressure elastic state to a fracture and plastic zone in the deep coal. Stress in deep coal is transmitted along the triangular elastic core. Numerical simulation results closely match the excavation profile of the tunneling, providing valuable insights into the impact of mining activities. This study can provide reference for deformation of similar geological conditions and engineering situation.

A reduction-driven directed aggregation strategy for fabricating stretchable conductive core-sheath fibers in wearable electronics

Rapid advancement of wearable electronics is profoundly reshaping our daily lives. At the heart of these innovations, stretchable conductive fibers (SCFs) assume pivotal roles in the high-sensitivity strain sensing and the high-conductivity flexible electrical conduction. Here, the stretchable conductive core-sheath fibers (SCCFs) are developed by a reduction-driven directed aggregation strategy. A conductive sheath layer of the silver nanoparticles aggregation and an elastic core layer of polymer matrix constitute an SCCF with the effective interface bonding. An SCCF with the high initial conductivity of over 1.77 × 105 S m−1 is fabricated with the features of reliability and good washability through the systematic optimization. On one hand, leveraging the microcrack effect, the strain sensing with the high resistance sensitivity under subtle strain is achieved by using a straight SCCF. On the other hand, the SCCF with a three-dimensional helical structure is designed to act as the flexible electrical conduction with the low resistance sensitivity under great strain. Notably, these SCCFs not only exhibit exceptional sensitivity for monitoring human movements, but also demonstrate efficient electrical energy conduction capabilities. This work proposes a prospective strategy to fabricate the versatile SCFs with great reliability, stability, and durability for wearable electronics.

Optimization and Application of Coal Pillar in Fully Mechanized Mining Face based on Energy Analysis

Based on the theory of energy dissipation, a numerical model of goaf excavation was established by FLAC3D based on the backflow channel of Heilong Coal Industry 2202. The dissipative energy distribution characteristics of coal pillars with different widths were studied, and the dissipative energy evolution law of surrounding rock of goaf roadway was analyzed. With the increase of the width of coal pillar, the width of elastic core zone is positively correlated with the bearing capacity. The peak value of dissipated energy density decreases with the increase of the width of coal pillar, and the concentration degree and region of dissipated energy density on the side of coal pillar are greater than that on the side of solid coal pillar. The project is applied to Heilong 2201 working face, and the optimum width of coal pillar and its supporting scheme are given. The practice results show that when the width of coal pillar is 5m, the deformation of surrounding rock can be effectively controlled and the demand for safe and efficient production can be met.

The Moving Element Method for the Dynamic Responses of Floating Double-Plate Structures on the Shallow Water

In this paper, the dynamic behavior of floating double-plate structures under a moving load is investigated in great detail with different factors utilizing the moving element method (MEM). The structures in this study are very large floating structures (VLFSs). The Kirchhoff–Love theory is used to model two floating plates connected by a Winkler-type elastic core, whilst the water surrounding the structure is simulated by the shallow linear water wave theory. In order to improve the computational efficiency of moving load problems, the MEM is adopted. Since the MEM uses fewer discrete elements than those of the traditional finite element method (FEM), the computational cost is reduced. The proposed two-plate model helps to reduce the influence of the surrounding water on the upper plate. Several numerical results are presented to investigate the influence of the ratio of thickness between layers as well as core stiffness on the displacements with different water depths, and load speeds.

Layerwise models for supersonic flutter analysis of viscoelastic sandwich panels with curvilinear fibre composite skins

In this work, an assessment of layerwise finite element models for supersonic flutter analysis of soft core viscoelastic sandwich panels is presented, making use of various kinematic descriptions involving shear deformation theories and Lagrange z-expansions with thickness stretching, progressively refined to render numerically accurate and computationally efficient solutions. Numerical applications of sandwich panels include either viscoelastic or purely elastic core with skins of metal or laminated composite, using unidirectional or curvilinear fibres, considering thin and moderately thick panels, with core thickness ratios ranging from narrow to wide cores. A comprehensive assessment of the models predictive capabilities in free vibration analysis is carried out by comparison with three-dimensional exact solutions and numerical methods available in the literature. Even though it is concluded that layerwise first-order modelling, with no thickness stretching, ensures a fair compromise between numerical accuracy and computational efficiency in the aeroelastic flutter analysis of thin sandwich panels, layerwise high-order theories accounting for thickness stretching are rather necessary for the proper modelling of moderately thick sandwich panels, with either viscoelastic or purely elastic core.

Histochemical analysis, smooth muscle immunolocalization and volumetric density of the elastic system fibres of the ostrich (Struthio camelus) phallus.

There are few scientific reports on the histology of the phallus of ratite birds. The aim of this study was to conduct a histochemical analysis to determine the distribution of smooth muscle cells and the volumetric density (Vv) of the fibres of the elastic system in the ostrich phallus. Adult ostriches, 14 months old, were used. The phalluses were fixed in Bouin's solution and then transferred to a buffered formalin solution. They were then processed using standard histological stains for paraffin and slices were obtained. The following techniques were performed: HE, Picrosirius red, Alcian Blue at pH 1.0 and 2.5. The Periodic acid-Schiff reagent and Weigert's Resorcin-Fuchsin with previous oxidation were performed. The M42 test system was used to quantify the elastic system fibres. For immunohistochemical analysis, an anti alpha smooth muscle actin monoclonal antibody was used. The surface of the phallus is covered by a non-keratinized stratified squamous epithelium, which becomes stratified cylindrical in the region of the spermatic sulcus. No glands associated with the connective tissue were observed. The Vv of the elastic system fibres was 4.75%. Smooth muscle cells were visualized only in the walls of blood vessels through immunostaining, with an absence in the lymphatic sinuses. Despite similarities with other birds, such as the presence of a fibrous external axis, a lymphatic core, and a spermatic groove, the ostrich phallus shows marked differences, including the absence of an elastic core, a non-keratinized lining epithelium, and the absence of glands throughout its extension.

Role of Quark Matter and Color Superconductivity in the Structure and Tidal Deformability of Strange Dwarfs

In 1995, Glendenning, Kettner and Weber postulated the existence of a new class of compact stars resembling white dwarfs but containing a small strange quark-matter core surrounded by hadronic layers attaining much higher densities than those found in white dwarfs. In our previous study, we have shown that it could be possible to unmask these so-called strange dwarfs through gravitational-wave observations with future space-based detectors such as the Laser Interferometer Space Antenna. We calculated more realistic equations of state for the hadronic envelope, but the quark core was treated using the simplest MIT bag model. In this paper, we investigate more closely the role of the possibly solid core in the structure and the tidal deformability of strange dwarfs in the full general relativistic framework by considering different models of strange quark matter in the crystalline color -superconducting phase. We find that the effect of the extreme rigidity of the elastic core on the tidal deformability is almost completely canceled by the surrounding hadronic layers. However, in all cases, the tidal deformability of strange dwarfs remains sufficiently lower than that of white dwarfs, to be potentially observable with gravitational waves despite the uncertainties in the strange quark-matter equation of state.

Polyacrylate-graft-polypyrrole Copolymer as Intrinsically Elastic Electrodes for Stretchable Supercapacitors.

Constructing elastic electrodes with high mechanical and electrochemical stability remains a challenge in developing flexible supercapacitors. Instability of elastic composite electrodes stems from detachment of noncovalently associated electroactive components from elastic substrates under cyclic deformations. Herein, a novel all-organic copolymer consisting of polypyrrole grafted from a polyacrylate elastomer is proposed as elastic electrodes for stretchable supercapacitors. The single copolymer is obtained by graft polymerization in the swollen state, characterized by a wrinkled polypyrrole coating covalently attached on an elastic core. The copolymer is intrinsically elastic and maintains structural integrity under bending, twisting, and stretching deformations to ensure stable electrochemical performance. In addition, the grafted polypyrrole aggregates densely under the constraint of the backbone and gives a competitive conductivity of 41.6 S cm-1. A stretchable supercapacitor is constructed using the copolymer as electrodes and an acid hydrogel as an electrolyte, resulting in a specific capacitance of 430 mF cm-2. The supercapacitor delivers a capacitance retention of 100% after 1000 stretching-releasing cycles, exhibiting mechanical and electrochemical reliability under elastic deformations.

Nutritional, Physico-Chemical, Phytochemical, and Rheological Characteristics of Composite Flour Substituted by Baobab Pulp Flour (Adansonia digitata L.) for Bread Making.

The aim of this paper is to improve the nutritional quality of bakery products by replacing wheat flour (WF) with different proportions (10%, 20%, and 30%) of baobab flour (BF). The composite flours and bread obtained were evaluated from nutritional, physical-chemical, phytochemical, organoleptic, and rheological points of view. The results obtained show that BF is a rich source of minerals (K: 13,276.47 ± 174 mg/kg; Ca: 1570.67 ± 29.67 mg/kg; Mg: 1066.73 ± 9.97 mg/kg; Fe: 155.14 ± 2.95 mg/kg; Na: 143.19 ± 5.22 mg/kg; and Zn: 14.90 ± 0.01 mg/kg), lipids (1.56 ± 0.02 mg/100 g), and carbohydrates (76.34 ± 0. 06 mg/100 g) as well as for the phytochemical profile. In this regard, the maximum contents for the total polyphenols content (TPC) were recorded in the case of bread with 30% BF (297.63 ± 1.75 mg GAE/100 g), a total flavonoids content (TFC) of 208.06 ± 0.002 mg QE/100 g, and 66.72 ± 0.07% for antioxidant activity (AA). Regarding the physical-chemical, rheological, and organoleptic analysis, the bread sample with 10% BF (BWB1) was the best among the samples with different proportions of BF. It presented a smooth, porous appearance (73.50 ± 0.67% porosity) and an elastic core (85 ± 0.27% elasticity) with a volume of 155.04 ± 0.95 cm3/100 g. It had better water absorption (76.7%) than WF (55.8%), a stability of 5.82 min, and a zero-gluten index. The scores obtained by BWB1 for the organoleptic test were as follows: Appearance: 4.81; color: 4.85; texture: 4.78; taste: 4.56; flavor: 4.37; and overall acceptability: 4.7. This study shows that BF improved the nutritional quality of the product, organoleptic properties, α-amylase activity, viscosity, and phytochemical profile, resulting in composite flour suitable for the production of functional bread.

Reasonable Size Design and Influencing Factors Analysis of the Coal Pillar Dam of an Underground Reservoir in Daliuta Mine

Underground reservoir water storage technology has become one important way to achieve efficient coal mining and water resource protection in the western mining areas of China, and the width of coal pillar dams is an important factor affecting the safe operation of underground reservoirs. In order to study the limitations on the reasonable size of a coal pillar dam, Daliuta Mine was selected as the engineering background and a theoretical formula for the reasonable width of a coal pillar dam was proposed. By combining theoretical analysis with numerical simulation analysis, the main influencing factors of the coal pillar dam were compared and analyzed. The research results indicated that changes in the mining height and coal parameters can cause a sharp change in the width of the plastic zone of the dam body. Then, mine water will have an impact on the width of the plastic zone and the width of the elastic core. Moreover, when the width of the coal pillar is smaller than the theoretically calculated width of the coal pillar dam body, the deviator stress and vertical stress inside the dam will significantly increase, and the plastic zone of the dam will significantly expand.