Layered Shells Research Articles

Аналіз розподілу температури у двошаровій композитній циліндричній оболонці зумовленої конвективним теплообміном на її зовнішній поверхні

A non-stationary thermal conductivity problem for a two-layer cylindrical shell is formulated. The materials of the constituent layers of the shell are assumed to be homogeneous and isotropic. This shell is convectively heated by the external environment. The system of linear two-dimensional equations for the integral temperature characteristics summed over the component layers of the shell was used as the initial system of equations of the problem under consideration. When obtaining this system, the hypothesis of a linear distribution of temperature along the thickness of the entire shell was applied. On the basis of the developed two-dimensional mathematical model of thermal conductivity for layered cylindrical shells, a general solution to the thermal conductivity problem for a two-layered cylindrical shell was obtained. A temperature distribution was found for such a shell, which is locally convectively heated by the external environment in a rectangular region on the outer surface. For the numerical analysis, a metal-ceramic cylindrical shell was considered, the inner layer of which is made of tungsten, and the outer layer is made of ceramics. Under such a structure and conditions of heat exchange with the external environment for the considered shell, the effect of its geometric parameters and thermophysical characteristics of the materials of its component layers on the temperature field on the outer surface of the shell was investigated. The revealed new qualitative and quantitative regularities can be used to estimate temperature fields in composite elements of layered structures and in structures with one-sided coatings. The dependences of temperature distributions on geometric parameters and thermophysical characteristics obtained in this work are the basis of the theoretical basis for the analysis of temperature regimes of metal-ceramic cylindrical shells. In particular, metal-ceramic dental crowns to predict their temperature regimes are modeled by the two-layer metal-ceramic cylindrical shells described above, which are locally convectively heated by the external environment

SN 2021dbg: A Luminous Type IIP–IIL Supernova Exploding from a Massive Star with a Layered Shell

We present extensive observations and analysis of supernova (SN) SN 2021dbg, utilizing optical photometry and spectroscopy. For approximately 385 days following the explosion, SN 2021dbg exhibited remarkable luminosity, surpassing most Type II SNe (SNe II). This initial high luminosity is potentially attributed to interaction between the ejected material and the surrounding circumstellar material (CSM), as evidenced by the pronounced interaction signatures observed in its spectra. The subsequent high luminosity is primarily due to the significant 56Ni mass (0.17 ± 0.05 M ⊙) produced in the explosion. Based on the flux of flash emission lines detected in the initial spectra, we estimate that the CSM mass near the progenitor amounted to ∼(1.0–2.0) × 10−3 M ⊙, likely resulting from intense stellar wind activity 2–3 yr preceding the explosion. Considering the bolometric light curve, nebular spectrum modeling, and mass-loss rate, we suggest that the progenitor of SN 2021dbg was a red supergiant (RSG) with a mass of ∼20 M ⊙ and a radius of 1200 R ⊙. This RSG featured a thick hydrogen shell, which may have contained a region with a sharp decrease in material density, electron density, and temperature, contributing to its layered structure. This object demonstrates mixed features of Type IIP and IIL SNe, making it a transitional event linking the above two subclasses of SNe II.

Macro-modelling of GFRG infilled RC frames incorporating pivot hysteretic model

GFRG (Glass Fibre Reinforced Gypsum) panels present a viable alternative to conventional masonry infills in masonry infilled RC frames. Based on the experimental study on the lateral load behaviour of GFRG infilled RC frames, it was understood that the GFRG panels enhance the structural performance of the RC framed structure. To delve further into this, numerical modelling of GFRG infilled RC frames with different fillings inside the cavities of the panel was performed using SAP2000. The GFRG panels were modelled using nonlinear layered shell elements, while the interface between the GFRG web and the infill material was represented using multilinear plastic link elements. The monotonic lateral load–deflection behaviour and the in-plane hysteresis response were simulated by performing monotonic and cyclic pushover analyses. The cyclic pushover analysis incorporated pivot hysteretic models for the materials, hinges and links. Validation of the proposed numerical models was carried out by comparing the results with those obtained from the experimental study. Key parameters such as peak load, initial stiffness, stiffness degradation, and energy dissipation were carefully compared to ensure the accuracy and reliability of the proposed model. It was observed that the proposed numerical model was able to capture the monotonic and cyclic load–deflection behaviour and other performance parameters. The numerical model accurately predicted the peak load in the positive direction but overestimated the corresponding value in the negative direction. Moreover, the overestimation observed in the cumulative energy dissipated for all the specimens is relatively minor and does not significantly affect the overall accuracy of the model.

Debonding of Porous Coating: A Late Failure Mode of Uncemented, Partially Threaded Acetabular Components—Retrieval Analysis

Titanium plasma-sprayed (TPS) porous coatings have been used in total hip arthroplasty for decades. They are considered reliable, and very few failure cases have been described so far. This retrieval study described a series of 20 acetabular components—where total or partial debonding occurred during in vivo use and aimed to explain the underlying failure mechanisms. Implants were examined using optical and electron microscopy (SEM), metallographic sections of retrievals were prepared while pathologic samples of periprosthetic tissues were examined for presence of wear debris. Data from metallographic slides indicated that debonding was initiated at free borders of the coating and tended to progress at the interface between the TPS layer and the shell. In some cases, total debonding occurred leading material wear of both the TPS layer and acetabular shell leading to massive release of metallic debris and accelerated polyethylene wear in third body mechanism. SEM examination demonstrated that splats forming the TPS layer exhibited features suggesting a high temperature gradient between the plasma sprayed layer and the substrate material existed, leading to porosity of splats and suboptimal bonding strength. This study demonstrated that coating application parameters and certain design features (screw holes, fins) may promote long-term failure due to debonding. Surgeons should be aware of this complication as it is most likely underreported, while manufacturers should consider more rigorous pre-clinical testing as suboptimal coating bonding may result in failures during long-term clinical use.

Preparation and characterization of silicon nanoparticles (core) with gold nanoparticles (shell) configuration

Herein, we used a simple yet novel approach to create and characterize silicon nanoparticles Si NPs/core, gold nanoparticles AuNps/shell hybrid structure. The meso porous silicon layer was synthesized using a laser-supporting etching process with 50 mW/cm2 and 405 nm laser power density and illumination wavelength in a Teflon cell comprising a 1:3 volumetric ratio of 40 % HF in ethanol with etching current density of 25 mA/cm2 for 15 min. The SiNps/AuNps hybrid structure was synthesized by a simple ion reduction process of gold ions via dangling bonds of SiNps in an aqueous solution of HaUcl4 of 0.001 M for 5 min. The characterization of SiNps and SiNps/AuNps hybrid structure were investigated using FE-SEM, TEM, XRD and PL measurements. The results showed that the pores diameter ranged from 5 nm to 50 nm, while the average diameter of the SiNps core layer and AuNps shell layer are about 59.5 nm and 38 nm respectively. The surface morphology of the SiNps characterizes the synthesized hybrid structure; the PL emission of hybrid structure has a high intensity with blue shifting towards short wavelength compared with SiNps. Deposition of AuNps on SiNps led to synthesis more chemical stable hybrid structure with specific increase in the surface area.This resulting hybrid structure can be adoptedin various types of plasmonics and gas sensors in addition to optoelectronics devices.

Investigation of a composites in the form of a layered orthotropic shell

Investigation of a composites in the form of a layered orthotropic shell

Constructing Pd@Layered-CoOx/MFI Bifunctional Catalyst for Efficient Ethyl Acetate Oxidation: Boosted C═O Activation and *O Species Transformation.

Oxygenated volatile organic compounds (OVOCs), emitted in large quantities by the chemical industry, are a major contributor to the formation of ozone and subsequent particulate matter. For the efficient catalytic oxidation of OVOCs, the challenges of molecular activation and intermediate inhibition remain. The construction of bifunctional active sites with specific structures offers a promising way to overcome these problems. Here, the Pd@Layered-CoOx/MFI bifunctional catalyst with core-shell active sites was rationally fabricated though a two-step ligand pyrolysis method, which exhibits a superb oxidation efficiency toward ethyl acetate (EA). Over this, 13.4% of EA (1000 ppm) can be oxidized at just 140 °C with a reaction rate of 13.85 mmol·gPd-1·s-1, around 176.7 times higher than that of the conventional Pd-CoOx/MFI catalyst. The electronic coupling of the Pd-Co pair promotes the electron back-donation from Pd nanoparticles to the layered CoOx shell and facilitates the formation of Pd2+ species, which greatly enhances the adsorption and activation of the electron-rich C═O bond of the EA molecules. In addition, the synergy of these core-shell Pd@Layered-CoOx sites accelerates the activation and transformation of *O species, which inhibit the formation of acetaldehyde and ethanol byproducts, ensuring the rapid total oxidation of EA molecules via the Mars-van Krevelen mechanism. This work established a solid foundation for exploring robust bifunctional catalysts for deep OVOC purification.

Single-atom Mn sites confined into hierarchically porous core–shell nanostructures for improved catalysis of oxygen reduction

Applications of zinc-air batteries are partially limited by the slow kinetics of oxygen reduction reaction (ORR); Thus, developing effective strategies to address the compatibility issue between performance and stability is crucial, yet it remains a significant challenge. Here, we propose an in situ gas etching-thermal assembly strategy with an in situ-grown graphene-like shell that will favor Mn anchoring. Gas etching allows for the simultaneous creation of mesopore-dominated carbon cores and ultrathin carbon layer shells adorned entirely with highly dispersed Mn-N4 single-atom sites. This approach effectively resolves the compatibility issue between activity and stability in a single step. The unique core–shell structure allows for the full exposure of active sites and effectively prevents the agglomerations and dissolution of Mn-N4 sites in cores. The corresponding half-wave potential for ORR is up to 0.875 V (vs. reversible hydrogen electrode (RHE)) in 0.1 M KOH. The gained catalyst (Mn-N@Gra-L)-assembled zinc-air battery has a high peak power density (242 mW cm−2) and a durability of ∼ 115 h. Furthermore, replacing the zinc anode achieved a stable cyclic discharge platform of ∼ 20 h at varying current densities. Forming more fully exposed and stable existing Mn-N4 sites is a governing factor for improving the electrocatalytic ORR activity, significantly cycling durability, and reversibility of zinc-air batteries.

3D-printed channel-aligned core-sheath architecture with high sulfur loading for kinetics-enhanced Li–S battery

Sluggish kinetics in thick cathode with high sulfur (S) loading will lead to low active material utilization and fast capacity decay, thus hampering the practical applications of Li–S batteries. To tackle such issue, a slightly thickness-dependent cathode of activated carbon (AC)-S/single-walled carbon nanotube (SWNT)@SWNT with fast reaction kinetics is constructed via continuously printing core-sheath filaments. Such micro-filaments are composed of vertically aligned “thin AC-S/SWNT” in core layer and porous SWNT-strengthened shell layer, which constructs an appealing well-interconnected porous 3D architecture ensuring fast ion/electron/mass transport throughout the whole printed matrix, effectively expediting electrochemical kinetics even under a high S loading. Moreover, the SWNTs located in shell layer and intercalated in-between AC-S phase in core layer crosslink well for acting as the functional interlayer to suppress polysulfide shuttling, thereby enabling high S utilization. As a result, the 3D-printed thick AC-S/SWNT@SWNT cathode delivers outstanding gravimetric/areal capacity (752 mAh g−1/6.41 mAh cm−2 at 0.5C) and cycling performance under high S loading of 8.6 mg cm−2.

Study on preparation and properties of mineral compound suppressant

To address the problem of coal mine dust pollution, the performance characterisation method was used to optimise the C3 dust suppressor. On this basis, two dust suppressants suitable for different climatic conditions were prepared by adding 8 groups of OP-10 and SDS surfactants with different concentrations, namely D5, which is suitable for dry areas and has excellent permeability, and E6, which is suitable for wet areas and has excellent resistance to rain erosion. The results show that compared with single dust suppressant, D5 with 0.5% OP-10 and E6 with 0.6% SDS have neutral PH, the rate of wind erosion is lower than 0.2% at 20 m/s, and the cured layer shell is well preserved with good wettability, adhesion and curability. Observed by scanning electron microscope (SEM), the coal dust particles bonded tightly after spraying D5 and E6, which could effectively improve the dust suppression efficiency.

A REVIEW ON ADDITIVE MANUFACTURING (AM) MATERIAL - STATISTICS AND COMPARISIONS

Fused deposition modeling, also known as FDM, boasts a major edge in the manufacturing industry for its remarkable capacity to craft intricate components sans pricey tooling or manual labor. As is the case with any engineering process, selecting the right process parameters plays a critical role in determining the quality of FDM products. Hence, precise calibration of these parameters is essential to elevate the durability and functionality of printed parts. Our study seeks to explore the influence of five crucial FDM parameters, including layer height and shell thickness, on the tensile strength of build parts, with the ultimate goal of optimizing overall product performance. Keywords:Fusion Deposition Modeling (FDM), Shell thickness, precise calibration, durability, functionality of printed parts.

Integration of layered group IV selenides: From SnSe–SnSe2-xSx core-shell crystals to complex (SnSe–SnSe2-xSx)-GeSe van der waals heterostructures

The layered semiconductor tin selenide (SnSe) has received extensive interest due to its promising thermoelectric and ferroelectric properties. Integrating SnSe with other layered crystals in heterostructures can enable the modification of charge- and thermal transport, electrical polarization, and other properties such as chemical stability, optoelectronics, and photonics. Here, we demonstrate the vapor transport synthesis of single-crystalline SnSe monochalcogenide flakes that are spontaneously encapsulated in a thin layered SnSe2-xSx dichalcogenide shell. In a second growth step, such SnSe–SnSe2-xSx heterostructures are integrated with the monochalcogenide GeSe, which is laterally stitched to the SnSe side facets while preserving the dichalcogenide shell across the basal facets. This architecture is confirmed by optical microscopy, electron microscopy and diffraction, energy dispersive X-ray and Raman spectroscopies, as well as cathodoluminescence spectroscopy. The results extend our capabilities for materials integration by forming complex heterostructures with both vertical van der Waals interfaces and covalent lateral interfaces between layered semiconductors.

Highly Conductive Carbon/Carbon Composites as Advanced Multifunctional Anode Materials for Structural Lithium‐Ion Batteries

AbstractCurrently, structural lithium‐ion batteries (LIBs) typically use carbon fibers (CFs) as multifunctional anode materials to provide both Li+ storage and high mechanical strength. However, due to the obvious volume expansion of CFs in lithiation process, the fiber structure suffers rapid degradation during cycling. Herein, CFs‐reinforced carbon matrix (C/C) composites are proposed as multifunctional anodes for structural LIBs for the first time. The C/C composite presents distinctive core/shell structure, in which CF as the core supplies a fast and continuous electron conduction pathway along with excellent mechanical strength, while the layered pyrolytic carbon shell accommodates the volume change of CF and provides additional ion storage. The impact of the C/C microstructure on the ion/electron transport and the Li+ storage mechanism behind such a unique hybrid structure are explored. Owing to the structural advantages of the C/C composite, the LiFePO4||C/C full cell exhibits surprising electrochemical performances at high electrode mass loadings, which are far superior to those of the present structural LIBs and even surpass the commercial LIBs at the same mass loadings. Moreover, the pouch cell presents excellent mechanical strength and mechanical‐electrochemical coupling characteristics. This work demonstrates great potential of the C/C composites as new multifunctional anodes for high‐performance structural batteries.

Study on the bending and dimensional behavior of honeycomb latticed ONYX composite material

Engineering, architecture, and transportation all use honeycomb structures in various ways. Latticing, made possible by additive manufacturing (AM), may significantly speed up the creation of adaptable structures. The current study focuses on assessing the impact of various three-dimensional (3D)-printing features on the flexural behavior and dimensional studies of the honeycomb latticed micro-carbon fiber reinforced nylon (ONYX) material. The experiment is performed by varying the levels of 3D-printing features like layer thickness (LT), infill geometry (IG), build direction (BD), shell count (SC), and infill percentage (IP) to measure the bending strength, length deviation, and lattice surface morphology variation. The experimental results show that, the peak flexural strength of 79.84 MPa is attained with specimen fabricated at 0.1 mm LT, 50% IP, 0° BD, rectilinear IG, and SC of 3. And moreover, these respective 3D-printing feature levels resulted in an improved surface morphology on the latticed specimens. The length deviation results clearly depict that specimen fabricated at lower LT of 0.1 mm, higher SC of 3, rectilinear IG, 0° BD, and higher IP of 50% consequences in accurate profile with a lower length deviation of 0.117 mm. The fractography results clearly implies that the 0° oriented latticed ONYX composite results in a progressive fracture and results in higher bending stress. On the other hand, the 45° and 90° oriented latticed ONYX materials undergo tilted fracture and perpendicular mode of fracture, respectively. From that it is concluded that, the triangular-shaped honeycomb latticed ONYX materials are suitable for the development of brackets for the portable cameras, medical, and dental appliances like prosthetics for lightweight splints in postsurgery.

Cr2AlC and metals reactivity: Sintering and oxidation

Cr2AlC-20 wt% (Sn; Cu; Co; Fe; Ag) powder mixtures were hot isostatically pressed at 1000 °C for 4 h under 150 MPa to investigate the possible alloying behaviour of the metals with the MAX phase. The as-synthesized bulk materials were further oxidized at 1000 and 1200 °C for 10 h under dry air flux to study the effect of the alloying on the oxidation performance of the MAX phase. The metallic elements did not dissolve into the MAX phase grains: they mainly acted as oxidizing agents on the MAX phase grains, draining the aluminum from it to form intermetallic phases. The oxidation tests resulted in the formation of an alumina scale for most of the samples. The oxidation kinetic study shows no improvement of the oxidation behaviour of the Cr2AlC-metal composites as compared to pure bulk Cr2AlC. Sn spheres embedded in an alumina layer and empty alumina shells are respectively observed on the surface of the oxidized Cr2AlC–Sn and Cr2AlC–Ag composites.

Encapsulating carboxymethyl cellulose stabilized nanoscale ferrous sulfide with layered magnesium hydroxide shell for controlled reactivity release and long-term sequestration of Cr(Ⅵ)

Nanoparticulate iron sulfide (nano-FeS) is a highly effective and environmentally-friendly reducing agent for decontamination. However, challenges such as aggregation, poor mobility, and oxidative aging limit its application of in situ groundwater and soil remediation. Herein, we present a novel approach to enhance the feasibility and effectiveness of nano-FeS for in situ remediation by encapsulating carboxymethyl cellulose stabilized FeS nanoparticles with a layered magnesium hydroxide shell (referred to as CMC-FeS@Mg(OH)2). The novel CMC-FeS@Mg(OH)2 nanoparticles, with a suitable coating ratio (10 %–50 %), demonstrate considerably increased colloidal stability and enhanced mobility in porous media. This is mainly due to steric hindrance, and decreased attachment, blocking, and straining effects. The Mg(OH)2 shell obviously protects the reactivity of FeS nanoparticles and enhances their resistance to oxidation, ensuring their longevity and long-term decontamination effectiveness during practical field applications. The preserved reactivity of FeS core can be progressively released and fully recovered by modulating the Mg(OH)2 coating ration and the extent of dissolution. After the complete dissolution of the Mg(OH)2 shell, CMC-FeS@50 % Mg(OH)2 exhibits enhanced efficiency in Cr(VI) sequestration, increasing from 58 % to 92 % compared to bare FeS. The removal of Cr(VI) by CMC-FeS@Mg(OH)2 is a synergistic process, and the main mechanisms includes adsorption, reduction, ion exchange, and subsequent precipitation. These results demonstrate a promising and effective method to improve the mobility and longevity of FeS and enable the controlled reactivity release for in situ remediation of subsurface contamination.

Enhancing the Thermal Stability of Zein Particle-Stabilized Aeratable Emulsions Through Genipin-Protein Cross-Linking and Its Possible Mechanism of Action.

Protein particle-stabilized emulsions often lack thermal stability, impacting their industrial use. This study investigated the effects of genipin (GP)-zein cross-linked particles with varying GP-to-protein weight ratios (0/0.02/0.1:1) on emulsion thermal stability. Enhanced stability was observed at the GP level of 0.1. Heat treatment increased the covalent cross-linking in raw particles and emulsions. Isolated particles from heated emulsions grew in size (micrometer scale) with higher GP levels, unlike heated raw particles (nanoscale). GP-protein cross-linking reduced the droplet-droplet and particle-emulsifier interactions in the heated emulsion. Spectroscopic analysis and electrophoresis revealed that GP-zein cross-linking increased protein structural stability and inhibited nondisulfide and non-GP cross-linking reactions in heated emulsions. The GP-zein bridges between particles at the oil-water interface create strong connections in the particle layer (shell), referred to as "particle-shell locking", enhancing the thermal stability of emulsion significantly. This insight aids the future design of protein-particle-based emulsions, preserving properties like aeratability during thermal processing.

Seismic fragility analysis of nuclear containment structure using Bayesian logistic regression model

Nuclear containment structure serves as the critical shielding structure in nuclear power plants, and must maintain structural integrity under various conditions. Following the Fukushima nuclear accident, seismic safety of nuclear power plant structures has become a significant concern in nuclear engineering community. This study presents seismic fragility analysis of the nuclear containment structure subjected to far-fault ground motion based on Bayesian logistic regression model. A refined finite element model of the nuclear containment structure was developed using layered shell element with considering material nonlinear behavior. The maximum tensile strain and roof drift of the nuclear containment structure were analyzed. MATLAB scripts for the seismic fragility analysis method based on Bayesian logistic regression model were developed. Posterior samples for the parameter of fragility function parameters were obtained using developed scripts. The sensitivity of the proposed Bayesian logistic regression based seismic fragility analysis method was verified. Seismic fragility curves of the nuclear containment structure obtained with the minimized sum of squared error, maximum likelihood estimation and Bayesian logistic regression methods were compared in depth.

Revealing the role of a bridging oxygen in a carbon shell coated Ni interface for enhanced alkaline hydrogen oxidation reaction.

Encapsulating metal nanoparticles inside carbon layers is a promising approach to simultaneously improving the activity and stability of electrocatalysts. The role of carbon layer shells, however, is not fully understood. Herein, we report a study of boron doped carbon layers coated on nickel nanoparticles (Ni@BC), which were used as a model catalyst to understand the role of a bridging oxygen in a carbon shell coated Ni interface for the improvement of the hydrogen oxidation reaction (HOR) activity using an alkaline electrolyte. Combining experimental results and density functional theory (DFT) calculations, we find that the electronic structure of Ni can be precisely tailored by Ni-O-C and Ni-O-B coordinated environments, leading to a volcano type correlation between the binding ability of the OH* adsorbate and HOR activity. The obtained Ni@BC with a optimized d-band center displays a remarkable HOR performance with a mass activity of 34.91 mA mgNi-1, as well as superior stability and CO tolerance. The findings reported in this work not only highlight the role of the OH* binding strength in alkaline HOR but also provide guidelines for the rational design of advanced carbon layers used to coat metal electrocatalysts.

Interfacial-engineered MOFs-POPs derived Co@N-doped carbon catalyst in boosting peroxymonosulfate activation and pollutant degradation: Roles of microstructure and exposed facets

Developing potent and durable heterogeneous catalysts is pivotal for advancing the implementation of the advanced oxidation processes in wastewater remediation. Herein, the “alloy” networks which were fabricated by incorporating zeolitic imidazolate framework-67 (ZIF-67) into porous organic polymers (POPs) matrix, was demonstrated, following pyrolyzed to prepare a core-shell Co@N-doped carbon-based catalyst (Co@NC-HBPC). The catalytic activity of Co@NC-HBPC for peroxymonosulfate (PMS) was regulated by modulating the preferential cobalt facet orientation, which in turn could be modulated by adapting the incorporation of ZIF-67. The as-prepared Co@NC-HBPC showed desirable Co dispersion, high catalytic reactivity (over 97 % degradation of Nitenpyram (NTP) within 20 min), high stability (maintaining 89.8 % NTP oxidation in five cycles), and wide environmental adaptability towards Fenton-like reaction. Both quenching and probe experiments verified the dominant roles of hydroxyl radicals (•OH) and singlet oxygen (1O2) species in NTP degradation process. Texture coefficient (TC) analysis and theoretical calculations unraveled that the Co (200) facet displayed the highest activity for PMS activation, which could modulate the surface electronic structure of N-doped carbon layer shell. This study provides comprehensive insights into the synergistic effect of metal facet and material morphology in PMS activation, thus offering new prospects for designing highly efficient heterogeneous catalysts for environmental remediation.