Composite Spheres Research Articles

Analytical evaluation of the elastic stresses in a multilayer spherical pressure vessel

An explicit-form solution is constructed for a problem on elastic deformation of a multilayer spherical vessel due to uniform internal pressure. The vessel is assembled of perfectly connected elastic layers whose material properties may arbitrarily vary across their thickness. The solution is constructed through the use of the single solid approach along with the modified scheme of the direct integration method which allow for the consideration of the multilayer vessel as a composite sphere with piecewise-variable profiles of the material properties. As a result, the original problem is reduced to solving a governing integral equation of the second kind whose solution is constructed in the form of the explicit dependence on the internal pressure. The solution is verified by the comparison with exact solutions derived by making use the method of tailored solutions for specific benchmark problems. By comparing our with the one for a functionally-graded sphere, whose material properties are evaluated through the use of the micromodular homogenization technique, the specific features of the circumferential stress are analyzed.

The Development and Evaluation of Biosorbent Composite Spheres for the Adsorption and Quantification of Copper

Separation techniques are employed to treat and preconcentrate samples. Preconcentration commonly employs adsorption due to the wide range of sorbents available. The biosorbent composite has emerged as a highly effective alternative, primarily due to its selectivity for active sites and its impressive adsorption capability. This study aimed to assess and create a spherical biosorbent composite using cellulose acetate and avocado seed. The purpose of this work was to use a biosorbent composite for copper adsorption by flame atomic absorption spectrometry. The copper adsorption follows the Langmuir isotherm, which indicates that it occurs in a monolayer and is homogeneous. Additionally, the adsorption nature is favorable according to the RL factor. The highest capacity for copper adsorption is 0.121 mg g−1. The report describes the methodology and validation process for quantifying copper. The findings demonstrate that the composite biosorbent enables accurate preconcentration and quantification of copper found in decongestants.

Enhanced EMI Shielding Efficiency of Graphene Nanoplatelets and Glass Sphere Composite‐Loaded Ultralight Weight Flexible Polyurethane Foam

ABSTRACTGraphene nanoplatelets and glass sphere (GNP@GS) composite is prepared using a simple mixing process and is loaded in flexible polyurethane foam to produce ultralight weight, high‐performance, electromagnetic interference (EMI) shielding material. The presence of a glass sphere enhances the mobility of graphene nanoplatelets in a polymer matrix forming a continuous conductive network thereby achieving better electrical conductivity and enhanced EMI shielding efficiency. The electrical conductivity of the synthesized GNP@GS/PU foam composites was achieved between 5.69 × 10−8 and 13.25 × 10−4 S/cm at varying filler loading. The maximum shielding effectiveness (i.e., −24.43 dB) was found at 12 wt% GNP@GS‐loaded samples. The shielding results show that the composites have the potential to be employed as ultralight weight, flexible EM shielding materials. These materials are essential in many applications because they are good shield materials that prevent electronic equipment from electromagnetic‐interference, better heat dissipation from the device, and also flexible to support fall protection.

Synthesis of magnetic ferrite/carbon nano sphere composites (MFe2O4/CNS, M = Mn, Ni, Zn) for Rhodamine B degradation by catalyzing persulfate

Synthesis of magnetic ferrite/carbon nano sphere composites (MFe2O4/CNS, M = Mn, Ni, Zn) for Rhodamine B degradation by catalyzing persulfate

Preparation of low-sensitivity explosive composite spheres via oil-in-oil emulsion

In order to reduce mechanical sensitivity and improve process performance of TKX-50, spherical TKX-50/TATB composite was prepared via the oil-in-oil emulsion method with TKX-50 (Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate) and TATB (1,3,5-triamino-2,4,6-trinitrobenzene) as raw materials. Based on the experimental results, the ideal circumstances for the emulsion to stabilize were obtained. The SEM results of spherical TKX-50/TATB composite exhibited an excellent spherical structure and size distribution. Furthermore, the SEM, XRD, and FT-IR results of spherical TKX-50/TATB composite demonstrated composite effect of the two basic materials was good. Compared to raw TKX-50 and TATB, the activation energies of spherical TKX-50/TATB composite decreased by 32.75 kJ mol−1 and 33.61 kJ mol−1, respectively. The TKX-50/TATB physical mixture was compared with spherical TKX-50/TATB composite, which had a higher bulk density and flowability. The impact sensitivity H50 of spherical TKX-50/TATB composite was 66.1 cm, which was 50.6 cm higher than that of raw TKX-50, and its friction sensitivity was reduced from 32 % to 24 % compared with that of raw TKX-50.

Mechanical properties of cementitious metallic hollow sphere composite under compression

This study presents a novel cementitious metallic hollow sphere composite by integrating metallic hollow spheres (MHS) into a cement matrix. Experimental results show that while MHS reduce the stiffness and strength of cement matrix, they enhance deformability and energy absorption. Adding 0.5% polypropylene fibers significantly improves mechanical properties and changes failure mode from brittle to ductile. This work offers insights into MHS materials in civil engineering.

Hierarchical magneto-colorimetric labels for immediate lateral flow immunoassay of chlorothalonil residues

Quantitative detection of pesticide residues in food and environmental samples using an improved lateral flow immunoassay (LFIA) is of considerable importance for real-time analysis. This paper proposes a highly sensitive LFIA platform based on a hierarchical magneto-colorimetric compact. This compact serves as both the target magnetic enrichment substrate and a photosensitive label. Initially, a large porous dendritic silica template is prepared and doped with superparamagnetic ferric oxide nanoparticles (Fe3O4 NPs) and colloidal gold nanoparticles (AuNPs) at high densities within its vertical channels. The sequential assembly of central–radial channels allow for the three-dimensional integration of these two components, enabling independent control of their discrete functions without mutual interference. Following alkyl organosilicon encapsulation and silica sealing, the composite spheres are then applied in LFIA to detect chlorothalonil residues. Fe3O4 NPs enhance the binding efficiency to target analytes, while AuNPs amplify the signal, leveraging their high loading densities and robust optical properties. The developed LFIA platform exhibited a detection limit of 0.34 ng/mL for chlorothalonil and a linear range of 0.0085–824 ng/mL. The recoveries varied between 85.1 % and 103.1 %, and the relative standard deviations were 1.25%–8.84 %. This LFIA approach demonstrates high sensitivity, specificity, reproducibility and flexible detection modes, making it highly suitable for the on-site monitoring of pesticide residues.

MoSe2 nanosheets implanting on 3D hollow carbon sphere for high-efficiency electromagnetic wave absorption

Carbon-based electromagnetic wave absorption (EMA) materials are extensively studied due to their unique advantages. Nevertheless, impedance matching issues was still constraining their further research. Consequently, we successfully synthesized MoSe2 nanosheets implanting on 3D hollow carbon sphere (HCS@MoSe2) composites with core–shell structure. The complex core–shell structure high-entropy composites provided multiple dissipation mechanisms for efficient dissipation of incident electromagnetic wave energy. The implanting MoSe2 nanosheets optimized the dielectric constant of the composites, thus ensuring optimal impedance matching. The HCS@MoSe2-1 composites exhibit excellent EMA properties and a significant minimum reflection loss (RLmin) of −56.19 dB. And HCS@MoSe2-1 had an ultra-wide effective absorption bandwidth (EAB) of 7.43 GHz. The significant EMA capability attributed to the synergistic effects of conductive loss, polarization loss, and optimized impedance matching. This work paved a new path for synthesizing transition metal selenide-modified carbon-based composite materials, offering great potential as high-performance materials for EMA applications.

Analytical Solution for Predicting the Elastic Modulus of a Cement Slurry System with the Effect of Calcium Dissolution.

The dissolution of calcium ions in concrete in a low-alkalinity environment is an important factor causing a significant increase in the porosity of internal concrete, leading to a deterioration in its mechanical properties and affecting the durability of the concrete structure. In order to improve the reliability of concrete durability design and significantly increase the service life of concrete structures located in soft water environments, it is crucial to establish an analytical method to predict the elastic modulus (Edc) of cement slurry systems suffering from calcium dissolution. Firstly, the hydrated cement particles are regarded as a three-phase composite sphere composed of unhydrated cement particles (UC), a high-density hydrated layer (H-HL), and a low-density hydrated layer (L-HL). By introducing the equivalent inclusion phase (EQ) composed of UC and H-HL, the three-phase composite sphere model can be simplified into an equivalent hydrated cement particle model composed of EQ and L-HL. Finally, the Edc of the two-phase composite sphere composed of the equivalent hydrated cement particles and the porosity of the dissolved cement slurry system are solved by using elasticity theory. The effectiveness of the developed analytical method is verified by comparing it with third-party numerical results. Based on this method, the effects of hydration degree, volume ratio of calcium hydroxide (CH) to hydrated calcium silicate (C-S-H), and volume ratio of inner C-S-H to outer C-S-H on the Edc of the dissolved cement slurry system are analyzed. The parameter analysis indicates that among the three influencing parameters, the hydration degree has the greatest effect on the Edc of the dissolved cement slurry system. This study provides an analytical method for predicting Edc, which can provide some references for the durability design of concrete after calcium dissolution.

CO2‐Hydrogenation to Methanol over CuO/ZnO Based Infiltration Composite Catalyst Spheres

Multiple active component catalysts for efficient conversion of CO2 to Methanol (MeOH) are synthesized through coating γ‐Al2O3 carrier spheres by incipient wetness impregnation method (IWI). The well‐known bimetallic Copper Oxide/Zinc Oxide (CuO/ZnO) are promoted in three steps, first by Cerium Oxide (CeO2), then additionally with Zirconium Oxide (ZrO2) and finally with Calcium Oxide (CaO) resulting in four carrier catalysts with high surface area and catalyst pore. Quaternary and quinary carrier catalysts promoted with moderate CeO2, ZrO2 in the quaternary (20% CZCZ) and additionally with CaO (20% CZCZC) in the quinary catalysts demonstrate high CO2‐conversion ratios (16.2% and 18.7%) and space time yields (0.51 and 0.47 gMeOH h‐1 gCatalyst‐1) at 5 MPa and 250 °C reactor temperature. The high conversion ratios (XCO2) and good methanol space‐time‐yields (STYMeOH) are attributed to enhanced copper dispersion and several multi metal oxide component interactions essential to enhance CO2‐activation and ‐conversion through the catalytic systems as well as very high overall surface area. Compared to related studies, the carrier catalysts show superior conversion rates, proving the effectiveness of the introduced multi‐component carrier catalyst and extending the understanding of infiltrate composites as possible large‐scale application alternatives to precipitated MeOH catalyst systems.

Co3V2O8 composite carbon hollow spheres bidirectionally catalyze the conversion of lithium polysulfide to improve the capacity of lithium‐sulfur batteries

Although lithium‐sulfur batteries have a high theoretical energy density that is higher than lithium‐ion batteries, their development is limited by the slow kinetics of lithium polysulfide conversion. In this research, we utilize the excellent bidirectional catalysis and adsorption of lithium polysulfide by the bimetallic oxide Co3V2O8 composite carbon hollow sphere to address the kinetic obstacle of lithium‐sulfur battery. On the one hand, the carbon hollow sphere substrate provides a cavity that can hold a large amount of sulfur. On the other hand, it can limit the diffusion of lithium polysulfide by van der Waals forces. The combination of the above two points improves the capacity and stability of lithium‐sulfur batteries. It has a specific capacity of 1237.2 mAh g‐1 at 0.2 C current density and retains 603 mAh g‐1 after 100 cycles. At a high current density of 2 C, the specific capacity is 976.2 mAh g‐1. After 1000 cycles, it holds at 338.3 mAh g‐1, and the capacity retention rate per cycle is 99.89%. This work discovers the new potential of Co3V2O8 as an electrocatalyst and proposes a process that can widely prepare carbon materials with complex uniform distribution of electrocatalysts to achieve high specific capacity of lithium‐sulfur batteries.

The creeping movement of a soft colloidal particle normal to a planar interface

A methodological blend of analytical and numerical strategies employing collocation techniques is presented to investigate the task of describing the Stokes flow generated by a soft particle (composite sphere) moving perpendicularly to a planar interface of infinite extent, separating two semi-infinite, immiscible viscous fluid domains. The particle consists of a solid core enclosed by a porous membrane allowing fluid passage. The movement of the soft nanoparticle has been examined through a continuum mathematical model. This model incorporates the Stokes and Brinkman equations, accounting for the hydrodynamic fields both outside and within the porous membrane layer, respectively. The motion is investigated under conditions characterized by low Reynolds and capillary numbers, where the interface experiences negligible deformation. The solution combines cylindrical and spherical fundamental solutions via superposition. Initially, the boundary conditions at the fluid–fluid interface are satisfied utilizing Fourier–Bessel transforms, subsequently addressing the conditions at the soft particle's surface through a collocation method. The normalized drag force exerted on the particle is accurately calculated, exhibiting robust convergence across various geometric and physical parameters. These findings are effectively visualized via graphs and tables. We juxtapose our drag force coefficient results with established literature data, particularly focusing on the extreme cases. The findings highlight the substantial impact of the interface on the drag force coefficient. Across the full range of viscosity ratios, the normalized drag force decreases as the relative thickness of the porous layer increases. These results enhance the understanding of practical systems and industrial processes such as sedimentation, flotation, electrophoresis, and agglomeration.

In-situ honeycomb spheres for enhanced enzyme immobilization and stability

This paper presents a promising heterogeneous biocatalyst-immobilized cellulase system, which can facilitate the targeted catalytic conversion of biomass to reducing sugars. Magnetic Zeolite Imidazole Framework-8/chitosan (Fe3O4/ZIF-8/CS, FZC) hybrid honeycomb microspheres were synthesized to immobilize cellulase using an in-situ growth strategy. The enhancement of immobilization efficiency induced by each constituent of the composite carrier was explored. This exploration was grounded in varying combinations of components within the honeycomb composite spheres, revealing the indispensability of ZIF-8. Through in-situ assembly, the composite material presents a microsphere with an internal honeycomb structure and multilevel pores. Effective immobilization, temperature-responsive conformational change, and cyclic stability were achieved due to the scaling effect of the channel, extensive specific surface area, and abundant amino group interactions enable immobilized enzymes to maintain excellent performance under challenging operating conditions, demonstrating an enhanced structure-performance relationship. With the obtained immobilized cellulase, we achieved a high load (461.67 mg/g) of cellulase and a significant reducing sugar yield (328.39 mg/g) from corncob waste. In addition, we investigated the enhancement effect of thermal activation on the immobilized enzyme activity of composite carrier. The results showed that the appropriate heat treatment was conducive to the activation of FZC immobilized enzyme with a reducing sugar yield 1.61 times higher than that of the control. The strategy provided in this study promotes the development of immobilized biocatalysts and provides a useful reference for the further design of biocatalytic systems.

Slow Translation of a Composite Sphere in an Eccentric Spherical Cavity

This semi-analytical study is presented examining the quasi-steady creeping flow caused by a soft (composite) spherical particle, which is a hard (impermeable) sphere core covered by a porous (permeable) layer, translating in an incompressible Newtonian fluid within a non-concentric spherical cavity along the line joining their centers. To solve the Brinkman and Stokes equations for the flow fields inside and outside the porous layer, respectively, general solutions are constructed in two spherical coordinate systems attached to the particle and cavity individually. The boundary conditions at the cavity wall and particle surface are fulfilled through a collocation method. Numerical results of the normalized drag force exerted by the fluid on the particle are obtained for numerous values of the ratios of core-to-particle radii, particle-to-cavity radii, the distance between the centers to the radius difference of the particle and cavity, and the particle radius to porous layer permeation length. For the translation of a soft sphere within a concentric cavity or near a small-curvature cavity wall, our drag results agree with solutions available in the literature. The cavity effect on the drag force of a translating soft sphere is monotonically increasing functions of the ratios of core-to-particle radii and the particle radius to porous layer permeation length. While the drag force generally rises with an increase in the ratio of particle-to-cavity radii, a weak minimum (surprisingly, smaller than that for an unconfined soft sphere) may occur for the case of low ratios of core-to-particle radii and of the particle radius to permeation length. This drag force generally increases with an increase in the eccentricity of the particle position, but in the case of low ratios of core-to-particle radii and particle radius to permeation length, the drag force may decrease slightly with increasing eccentricity.

Micromechanics modeling of cement concrete considering the interaction among randomly oriented ellipsoidal inhomogeneities

To account for the random orientation of ellipsoidal inhomogeneities, the averaging process over two Euler angles has been widely used in existing micromechanics models. However, the interaction among various inhomogeneity orientations is often overlooked and may also affect the prediction of composite elastic modulus. In this work, to consider the interaction among randomly oriented aggregates and fibers in cement concrete, a micromechanics model, the orientation interaction model (OIM), is proposed. An orientation average model (OAM) is also proposed, and by comparing OIM and OAM predictions, the effect of inhomogeneity orientation interaction on the predicted elastic modulus is shown. In both models, geometries of coarse aggregates and fibers are approximated using ellipsoids with three different semiaxes and cylinders, respectively, and their orientations are described using three Euler angles. Compared with existing random orientation models using two Euler angles, the proposed models can capture the isotropy of composites with randomly oriented asymmetric ellipsoidal inhomogeneities. By comparing the predictions of OIM, OAM, composite sphere models and the Mori-Tanaka method with spherical inhomogeneities, it is found that with the increase of the stiffness contrast between the matrix and inhomogeneities, the effects of the inhomogeneity geometry and orientation interaction become more apparent. The model predictions agree well with the experimental data. By changing the value range of three Euler angles based on the inhomogeneity orientation distribution, both models are also suitable for transversely isotropic and anisotropic composites containing several types of inhomogeneities.

Cleansing the molten steel due to the dispersed in-situ phase induced by the composite sphere burst reaction I. Composite sphere design

In the present investigation, a novel fine inclusion removal technology due to the dispersed in-situ phase induced by composite ball burst reaction was put forward. A composite sphere with this function was designed and the composite sphere burst process at steelmaking temperature was analysed. The results indicate that the compact strength of the composite ball is so high that it will not break up as it intrudes into the molten steel. The composite sphere has a high thermal stability at steelmaking temperature. Usually, the composite sphere burst reaction takes place after it has intruded into the molten steel for a few seconds. The fine bubbles and slag droplets can be released due to the composite sphere burst reaction. Compared with the conventional technology, the bubbles and slag droplets induced by this novel technology are much finer. The size distribution of the bubble and the slag droplet is between 20 and 200 μm. The dispersion of these fine bubbles and slag droplets contributes to collision with inclusion.

Urchin-Like Mesoporous TiN Hollow Sphere Enabling Promoted Electrochemical Kinetics of Bromine-Based Flow Batteries.

Bromine-based flow batteries (BFB) have always suffered from poor kinetics due to the sluggish Br3 -/Br- redox, hindering their practical applications. Developing cathode materials with high catalytic activity is critical to address this challenge. Herein, the in-depth investigation for the free energy of the bromine redox electrode is conducted initially through DFT calculations, establishing the posterior desorption during oxidation as the rate-determining step. An urchin-like titanium nitride hollow sphere (TNHS) composite is designed and synthesized as the catalyst for bromine redox. The large difference in Br- and Br3 - adsorption capability of TNHS promotes rapid desorption of generated Br3 - during the oxidation process, liberating active sites timely to enable smooth ongoing reactions. Besides, the urchin-like microporous/mesoporous structure of TNHS provides abundant active surface for bromine redox reactions, and ample cavities for the bromine accommodation. The inherently high conductivity of TNHS enables facile electron transfer through multiple channels. Consequently, zinc-bromide flow batteries with TNHS catalyst exhibit significantly enhanced kinetics, stably operating at 80mAcm-2 with 82.78% energy efficiency. Overall, this study offers a solving strategy and catalyst design approach to the sluggish kinetics that has plagued bromine-based flow batteries.

Environmentally friendly zero-valent iron-modified biochar beads for high-performance antimonite removal from aqueous solution

Antimony (Sb) contamination in aquatic environments has emerged as a significant environmental concern because of extensive industrial activities involving Sb and its associated health hazards. Nano-zero-valent iron (nFe) is recognised for its efficacy in heavy metal remediation; however, its application is often hindered by poor dispersion and suboptimal adsorption properties. We designed an innovative approach in which nFe is calcined with biochar to mitigate agglomeration and subsequently amalgamated with sodium alginate to form composite gel spheres (PEI/SA/BCFe) in a calcium chloride solution. The ability of these gel spheres to remove antimonite (Sb(III)) from water was evaluated under various conditions, including pH, initial concentration, the presence of competing ions, temperature, and cycling experiments. The R2 fitted to the Langmuir isotherm were 0.99, 0.96 and 0.97, respectively. The adsorption was carried out under thermostatic shaking conditions, and the maximum adsorption capacity was 621.04 mg g−1, 509.34 mg g−1, and 373.10 mg g−1 at 10, 25, and 40 °C, respectively, which corresponded to removal efficiencies of 72.5%, 65.3% and 63.7%, respectively. The underlying mechanisms driving the adsorption process were primarily attributed to the oxidation of Sb(III), inner-sphere complexation, and coprecipitation. This comprehensive study not only highlights the potential of PEI/SA/BCFe as an effective solution for mitigating antinomy contamination in water but also contributes valuable insights into the mechanistic aspects of heavy metal adsorption.

Cleansing the molten steel due to the dispersed in situ phase induced by the composite sphere explosion reaction II. Inclusion removal

Industrial trials have been carried out on the base of the former experimental research and the CaCO3 proportion in composite sphere, feeding amount, and composite sphere feeding mode have been investigated. The fine inclusion removal mechanism has been analyzed. The results indicate that feeding composite sphere in RH degasser is a novel process and small inclusion in the molten steel can be removed effectively. CaCO3/CaO ratio in composite sphere has a great effect on the inclusion removal efficiency. More feeding times and a little feeding amount can increase the composite sphere utilization efficiency. Compared with the conventional inclusion removal technology, the number density of the oxide inclusion can be decreased to a lower level and the inclusion size becomes much finer. Using this novel process, T.O. in the as-cast slab can approach to 6 ppm.

Exploring drug release performance of hollow‐structured CS/SA/POSS composite gel spheres employing hydrophilic polymerizable AS‐POSS as crosslinker

AbstractThis study prepares a series of hollow‐structured CS/SA/POSS composite gel spheres with a diameter of ~2.5 mm by using hydrophilic Janus‐type polyhedral oligomeric silsesquioxane (AS‐POSS) as a crosslinking agent in combination with sodium alginate and chitosan via electrostatic adsorption/free radical polymerization. As the content of POSS increases, the wall thickness of the gel spheres also increases from 20 to 30 μm, leading to a more compact and smooth wall structure in the polymerized CS/SA/POSS composite gel spheres. Additionally, the introduction and polymerization of POSS significantly enhance the stability, drug loading rate, and entrapment rate of the gel spheres, providing them with improved drug release capabilities. For hydrophilic drug doxorubicin, the loading rate and encapsulation rate reach 41.2% and 79.9%, respectively, while for the hydrophobic drug ibuprofen, they are 14.7% and 76.3%. Compared to some previously reported drug‐loaded gel materials, the gels prepared in this study demonstrate relatively higher drug loading performance. Thus, these hollow‐structured CS/SA/POSS composite gel spheres hold promise as innovative drug carriers in the biomedical field.