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We develop low-order triangular virtual elements for linear Kirchhoff–Love shells from an engineering point of view. Flat element geometry is considered, which enables a direct shell discretization with no need for a curvilinear coordinate system or predefined initial mapping. Along with the assumed linearity of the problem, the superposition of the uncoupled membrane and plate energies is performed by unifying aspects of the virtual element method when applied to linear two-dimensional elasticity and plate bending problems. We explore low-order cases, namely linear to quadratic membrane displacements and quadratic to cubic deflection polynomial approximations such that no internal degrees of freedom are needed. For all elements, a single stabilization available in the literature is employed to stabilize the element formulations. Numerical examples of static problems show that the presented formulation is capable of solving complex shell problems. Possible extensions are discussed in future works. [ABSTRACT FROM AUTHOR]

This paper presents a modified evaluation approach for the structural-capacity-reserve (SCR) based on the static stability behavior of single-layer spherical lattice shells to achieve more accurate assessment results of seismic damage endurance. The SCR index in this paper is calculated by integrating the redefined residual structural capacity (RSC) ratio based on post-earthquake static stability behavior within the range of damage degrees caused by strong earthquakes. Compared with the assessment work for seismic damage endurance in the existing literature, the proposed RSC ratio in this paper could take into account both ultimate load-bearing strength and residual deformation. Additionally, the specific quantitative indicator in the proposed assessment method should also be determined according to whether the residual nodal displacement of the lattice shell after an earthquake exceeds the limit value state specified by the design code. The numerical results in the case study indicate that the residual load-bearing strength of the lattice shell remains relatively constant under the same damage state induced by different earthquakes, with residual deformation significantly impacting the assessment of seismic damage endurance. Thereby, the required RSC can be controlled by reducing the residual nodal displacements of the lattice shell under strong earthquakes to achieve a well-balanced design scheme. [ABSTRACT FROM AUTHOR]

The electrochemical nitrate reduction reaction (NO3−RR) presents an environmentally friendly approach for efficient NO3− pollutant removal and ammonia (NH3) production, compared to the conventional Haber–Bosch approach. While core/shell engineering has demonstrated its potential in enhancing NO3−RR performance, significant synthetic challenges and limited shell layer modification capabilities impede the exploration of high‐performance NO3−RR core/shell catalysts. Herein, CuCoO/Co(OH)2 core/shell structure via in situ electrochemical activation is synthesized. The catalyst delivers a maximum NH3 Faradaic efficiency (FE) of 94.7% at −0.5 VRHE with excellent durability and selectivity for NH3 over a wide range of potentials in NO3−RR, surpassing the electrocatalytic performance of both undoped shell and core components. The outstanding performance Cu─CoO/Co(OH)2 is ascribed to the enhanced charge transfer, stabilization of key reaction intermediates, and regulation of hydrogen adsorption over Cu‐doped core/shell structure. Furthermore, the assembled Zn−NO3− battery device attains a peak current density exceeding 32 mA cm−2 and an NH3 yield of up to 145.4 µmol h−1 cm−2. The work offers a novel core/shell engineering strategy in electrocatalytic NO3−RR and sheds light on the doping effects on the electrochemical NH3 synthesis. [ABSTRACT FROM AUTHOR]

Balanomorph (acorn) barnacles are found throughout the world's coastal oceans, and their success is dependent on a hard, mineralized, outer shell. Although macro-scale morphology of barnacle shells has been studied extensively, relatively little is known about shell properties at the micron-scale and if such properties vary among species. We assessed shell structure, mechanics, and composition in seven species of balanomorph barnacles from five genera. Three species, Amphibalanus amphitrite, Amphibalanus improvisus, and Austrominius modestus, were laboratory-reared, enabling direct comparison of shell properties of barnacles grown under the same conditions for the same duration. Four other species, Semibalanus balanoides, Amphibalanus eburneus, Chthamalus stellatus, and Tetraclita rubescens, were field-collected. At the macro- and meso-scales, shell properties varied markedly among species, with differences in the number of shell plates, the presence of canals within the plates, mineralization of the base, and shell plate thickness. At the micron-scale, however, structure was remarkably similar among species. Plates of all species were constructed of irregular micron-scale crystallites, with a broad range of crystallite dimensions observed within the same shell. Similarly, micromechanical properties did not vary among species, regardless of testing orientation. Calcium carbonate was identified as calcite in all species assessed with no other mineral phases present, and calcium content did not vary among species. Hence, despite variation in the overall macro- and meso-scale morphology of barnacles, all appear to be built using the same, evolutionarily conserved, mineralization pathway. [ABSTRACT FROM AUTHOR]

Buffer energy absorbing structures have very high use value in daily life, industrial production, aerospace and other fields. Cylindrical shells are used as a highly efficient buffer and energy absorbing structure due to their own structure and good mechanical properties. Taylor impact experiments were conducted on three types of structural cylindrical shells (non grooved, inner grooved, and outer grooved) and numerical model was also established to study and analyze the dynamic response characteristics of the three types of structural cylindrical shells. Finally, the deformation mechanism of the cylindrical shell was analyzed theoretically to explore the impact of grooving treatment on the deformation of the cylindrical shell. The results show that with the increase of impact velocity, the length of the cylindrical shells of the three structures decreased, and the diameter of the impact end and the maximum diameter increased. Each of the three specimens had a convergence velocity(convergence velocity: The impact end diameter of cylindrical shell is the initial impact velocity at the maximum diameter), that is, when the impact velocity was greater than or equal to the convergence velocity, its maximum diameter was equal to the diameter of the impact end. When the impact velocity exceeded a certain value, the deformation modes of the three types of cylindrical shells changed. The comparison of experimental and simulation results proved the effectiveness of the numerical model. The maximum stress was always above the impact end face. It was concluded from the theoretical analysis Due to the stress concentration at the groove, the stress distribution and internal stress distribution of the cylindrical shell were affected, which in turn affected the deformation and energy absorption capacity of the cylindrical shell. At the same impact velocity, the outer grooved cylindrical shell has the shortest buffer time and the BW specimen had the most gentle buffer curve before 35μs. [ABSTRACT FROM AUTHOR]

Advancements in synthetic biology have facilitated the incorporation of heterologous metabolic pathways into various bacterial chassis, leading to the synthesis of targeted bioproducts. However, total output from heterologous production pathways can suffer from low flux, enzyme promiscuity, formation of toxic intermediates, or intermediate loss to competing reactions, which ultimately hinder their full potential. The self-assembling, easy-to-modify, protein-based bacterial microcompartments (BMCs) offer a sophisticated way to overcome these obstacles by acting as an autonomous catalytic module decoupled from the cell's regulatory and metabolic networks. More than a decade of fundamental research on various types of BMCs, particularly structural studies of shells and their self-assembly, the recruitment of enzymes to BMC shell scaffolds, and the involvement of ancillary proteins such as transporters, regulators, and activating enzymes in the integration of BMCs into the cell's metabolism, has significantly moved the field forward. These advances have enabled bioengineers to design synthetic multi-enzyme BMCs to promote ethanol or hydrogen production, increase cellular polyphosphate levels, and convert glycerol to propanediol or formate to pyruvate. These pioneering efforts demonstrate the enormous potential of synthetic BMCs to encapsulate non-native multi-enzyme biochemical pathways for the synthesis of high-value products [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) nanocrystals are promising for optoelectronic and microelectronic technologies. However, the performance of 2D nanocrystal light-emitting diodes (LEDs) remains limited. Here, exciton dynamics are rationally controlled by both shell engineering and device engineering, obtaining colloidal quantum well LEDs (CQW-LEDs) with superior performance. The formation of CQW films on charge transport layers shows an excellent photoluminescence quantum yield of 76.63%. An unreported relationship among Auger lifetime, electron confinement energy, and external quantum efficiency (EQE) in 2D nanocrystal devices is directly observed. The optimized CQW-LEDs possess a maximum power efficiency of 6.04 lm W−1 and a current efficiency of 9.20 cd A−1, setting record efficiencies for 2D nanocrystal red LEDs. Additionally, a remarkable EQE of 13.43% has been achieved, accompanied by an exceptionally low efficiency roll-off. Significantly, EQE for flexible CQW-LEDs is 42-fold higher than the previous best results. Furthermore, active-matrix CQW-LEDs on printed circuit boards are developed. The findings not only unlock new possibilities for controlling exciton dynamics but also provide an alternative strategy to achieve high-performance 2D nanocrystal based applications. [ABSTRACT FROM AUTHOR]

Percolating composites present giant dielectric constant (ε′) at the critical filler loading (fc), whereas the accompanied undesirable high loss and leakage current significantly limit their wide applications owing to the deteriorated breakdown strength (Eb). To prohibit the unwished large loss and leakage current of the graphite nanosheets (GNS)/poly(vinylidene fluoride, PVDF) while still keeping a high ε′, the titanium dioxide (TiO2) encapsulated GNS, i.e., GNS@TiO2, were first obtained in this study via a sol-gel technology, and then composited with PVDF to explore the TiO2 shell's impact and modulation effect on the dielectric properties of the nanocomposites. The findings on the relationship between structure and dielectric parameters reveal that the presence of a TiO2 interlayer not only strengthens the interface interactions, but also remarkably relieves the pronounced interfacial mismatch in both ε′ and electric conductivity between the filler and host matrix, thus leading to boosted Eb of the nanocomposites. Moreover, the dielectric loss and conductivity of the nanocomposites can be significantly suppressed and reduced to rather low levels because of the introduced deep traps resulting from the interlayer frustrating the long-distance electron migration. And the integrated dielectric properties of the GNS@TiO2/PVDF can be effectively regulated by adjusting the GNS@TiO2's electric resistivity and optimizing the TiO2 shell thickness. This work offers a beneficial strategy for the design of percolating nanodielectrics with high εr and Eb but suppressed loss for prospective applications in microelectronic devices and power equipment. [ABSTRACT FROM AUTHOR]

In this study, nonlinear buckling response of composite sandwich semi-ellipsoidal shell subjected to uniform hydrostatic external pressure is investigated numerically and experimentally. The face sheet of the sandwich shell is made up of laminated composite layers and the honeycomb core is considered as reinforced with and without strips. The various honeycomb core configurations with strip reinforcements are employed in the sandwich semi-ellipsoidal shell. The numerical buckling analysis of the sandwich shell is performed using the commercially available software ANSYS®. The geometric nonlinearity and material nonlinearity of the shell structures are included through the arc length method while solving the nonlinear differential equations and identifying the critical pressure of the structure. The efficacy of the numerical modeling and analysis are verified by comparing the critical pressure obtained through the experimental investigations performed on a composite semi-ellipsoidal sandwich shell and results available in the literature. The various parametric investigations are performed on the composite sandwich shell to study the effect of honeycomb configurations, ply orientation of face sheets, aspect ratio and slenderness of the structure, geometric imperfections on the critical pressure. It was seen that the semi-ellipsoidal sandwich shell having double strip reinforcement core yields higher critical pressure among the various configurations of honeycomb cores. However, the semi-ellipsoidal sandwich shell with the single strip reinforcement in between the core having [0°]6s face sheet composite ply configuration yields higher stiffness to weight ratio which leads to the highest critical pressure among the various configurations of sandwich shell. [ABSTRACT FROM AUTHOR]

This study investigates bidirectionally sinusoidal corrugated steel shells using finite element analysis (FEA) software, primarily ABAQUS 2017, supplemented by RFEM 6.05 for an initial result comparison. The research aims to establish a robust numerical solution to understand the structural behaviour of these shells under static and dynamic loading. Starting with meticulous calculations for a selected structural element, the paper emphasises a comparative analysis between ABAQUS and RFEM, offering valuable insights into simulating the responses of corrugated steel shells. A distinctive contribution of this research lies in its novel and comprehensive parametric analysis of these shells under static and dynamic loading, an area that has not been explored in previous studies. The study systematically explores various model parameters, including geometrical and mechanical properties, with detailed analyses revealing their influences on deformation, stress distribution, dynamic properties, and behaviour. Another key feature is the development of a coded script that systematically generates diverse numerical models, allowing for a thorough exploration of the structural system's response. This study advances our understanding of the structural behaviour of bidirectionally sinusoidal corrugated steel shells. These findings are set to enhance structural analysis and design practices by optimising parameters for improved performances in various engineering applications. [ABSTRACT FROM AUTHOR]

This study proposes an improved mixed-variable quantum particle swarm optimization (QPSO) algorithm capable of optimizing both continuous and discrete variables. The algorithm is applied to the wind resistance optimization of a cable-stiffened, single-layer spherical reticulated shell (SLSRS), optimizing discrete variables like member dimensions and cable dimensions alongside continuous variables such as cable prestress. Through a computational case study on an SLSRS, the optimization results of the proposed QPSO method are compared with other optimization techniques, validating its accuracy and reliability. Furthermore, this study establishes a mathematical model for the wind resistance optimization of cable-stiffened SLSRSs and outlines the wind resistance optimization process based on the mixed-variable QPSO algorithm. The optimization of these structures reveals the strong stability and global search capabilities of the proposed algorithm. Additionally, the comparison of section optimization and shape optimization highlights the significant impact of the shell shape on steel usage and costs, underscoring the importance of shape optimization in the design process. [ABSTRACT FROM AUTHOR]

We study free vibrations of open noncircular cylindrical shells with elliptic cross sections. A computational model based on the finite-element method is developed. Numerical calculations were carried out for several versions of boundary conditions imposed at the ends. The numerical analysis makes it possible to establish the dependence of frequencies and the modes of free vibrations of noncircular cylindrical shells on the eccentricity of the elliptic cross section and the type of cutting of the shell. The obtained results are important for the evaluation of the load-carrying capacity of structural shell elements of the corresponding shape. [ABSTRACT FROM AUTHOR]

Solar‐driven photoelectrochemical (PEC) reactions using colloidal quantum dots (QDs) as photoabsorbers have shown great potential for the production of clean fuels. However, the low H2 evolution rate, consistent with low values of photocurrent density, and their limited operational stability are still the main obstacles. To address these challenges, the heterostructure engineering of asymmetric capsule‐shaped CdSe/CdxZn1‐xSe QDs with broad absorption and efficient charge extraction compared to pure‐shell QDs is reported. By engineering the shell composition from pure ZnSe shells into CdxZn1‐xSe gradient shells, the electron transfer rate increased from 4.0 × 107 s−1 to 32.7 × 107 s−1. Moreover, the capsule‐shaped architecture enables more efficient spatial carrier separation, yielding a saturated current density of average of 25.4 mA cm−2 under AM 1.5 G one sun illumination. This value is the highest ever observed for QDs‐based devices and comparable to the best‐known Si‐based devices, perovskite‐based devices, and metal oxide‐based devices. Furthermore, PEC devices based on heterostructured QDs maintained 96% of the initial current density after 2 h and 82% after 10 h under continuous illumination, respectively. The results represent a breakthrough in hydrogen production using heterostructured asymmetric QDs. [ABSTRACT FROM AUTHOR]

The present study is focused on the numerical and experimental investigation of the non-linear buckling behavior and ply-failure analysis of a hybrid composite shell under uniform hydrostatic pressure exposed on its outer surface. Laminated composite shells made of glass fiber reinforced polymer (GFRP) composites with and without multi-walled carbon nanotubes (MWCNT) reinforcement are considered for the investigation. The critical buckling pressure is numerically determined by performing a buckling analysis on a hybrid composite shell with consideration of various non-linearities such as material non-linearity, geometric non-linearity, and geometric imperfection using the commercially available software ANSYS®. The governing non-linear differential equations of composite shell structures are solved using the arc-length approach and non-linear finite element analysis. The nanotubes dispersion, distribution, structural integrity, aspect ratio, functional group, and purity level of CNT reinforcement with epoxy matrix materials are quantified using field emission scanning electron microscopy (FE-SEM). The elastic and plastic properties of the GFRP lamina with and without MWCNT reinforcement are experimentally determined based on ASTM D3039. The critical buckling pressure obtained through experiments on a GFRP composite shell with and without MWCNT reinforcement is compared with the results obtained from the numerical analysis to validate the effectiveness of the present numerical model. Parametric studies are undertaken to investigate the first ply failure analysis, the effect CNT reinforcement, aspect ratio of MWCNT, and different lamination sequences on the critical buckling pressure of the composite shell. It was observed that the Von-Misses stresses developed on the composite structures with ply angles of either all layers as 0° or combination of ply angles with 0° and 90° is always less than those of the structures having ply-angles such as 45° and 60°, irrespective of CNTs reinforcement. Furthermore, the highest critical buckling pressure was obtained with reinforcement of 1.5 wt% MWCNT in the composite shell with ply orientation of [90°]4s. [ABSTRACT FROM AUTHOR]

Quantum dot light-emitting diodes (QLEDs) hold great promise for next-generation display applications owing to their exceptional optical properties and versatile tunability. In this study, we investigate the effects of quantum dot (QD) shell thickness, polyethylenimine (PEI) concentration, and PEI layer position on the performance of inverted QLED devices. Two types of alloyed-core/shell QDs with varying shell thicknesses were synthesized using a one-pot method with mean particle sizes of 8.0 ± 0.9 nm and 10.3 ± 1.3 nm for thin- and thick-shelled QDs, respectively. Thick-shelled QDs exhibited a higher photoluminescence quantum yield (PLQY) and a narrower emission linewidth compared to their thin-shelled counterparts. Next, QLEDs employing these QDs were fabricated. The incorporation of PEI layers on either side of the QD emissive layer significantly enhanced device performance. Using PEI on the hole transport side resulted in greater improvement than on the electron injection side. Sandwiching the QD layer between two PEI layers led to the best performance, with a maximum external quantum efficiency (EQE) of 17% and a peak luminance of 91,174 cd/m2 achieved using an optimized PEI concentration of 0.025 wt% on both electron injection and hole injection sides. This study highlights the critical role of QD shell engineering and interfacial modification in achieving high-performance QLEDs for display applications. [ABSTRACT FROM AUTHOR]

The large size of K‐ion makes the pursuit of stable high‐capacity anodes for K‐ion batteries (KIBs) a formidable challenge, particularly for high temperature KIBs as the electrode instability becomes more aggravated with temperature climbing. Herein, we demonstrate that a hollow ZnS@C nanocomposite (h‐ZnS@C) with a precise shell modulation can resist electrode disintegration to enable stable high‐capacity potassium storage at room and high temperature. Based on a model electrode, we identify an interesting structure‐function correlation of the h‐ZnS@C: with an increase in the shell thickness, the cyclability increases while the rate and capacity decrease, shedding light on the design of high‐performance h‐ZnS@C anodes via engineering the shell thickness. Typically, the h‐ZnS@C anode with a shell thickness of 60 nm can deliver an impressive comprehensive performance at room temperature; the h‐ZnS@C with shell thickness increasing to 75 nm can achieve an extraordinary stability (88.6 % capacity retention over 450 cycles) with a high capacity (450 mAh g−1) and a superb rate even at an extreme temperature of 60 °C, which is much superior than those reported anodes. This contribution envisions new perspectives on rational design of functional metal sulfides composite toward high‐performance KIBs with insights into the significant structure‐function correlation. [ABSTRACT FROM AUTHOR]

In this paper, the stability and local bifurcations of a composite laminated circular cylindrical shell with radially pre-stretched membranes are explored by using analytical and numerical methods. On the basis of the four-dimensional averaged equation in the case of 1:1 internal resonance, three types of critical points are studied in detail. They are characterized as (1) one pair of purely imaginary eigenvalues and two negative eigenvalues; (2) a simple zero and one pair of purely imaginary eigenvalues; (3) two pairs of purely imaginary eigenvalues in nonresonant case. With the aid of normal form theory and Maple software, the steady-state solutions and the stability regions of the initial equilibrium solutions are obtained. The explicit expressions for the critical bifurcation curves leading to static bifurcation and Hopf bifurcation are also presented. The presence of Hopf bifurcation indicates that the circular cylindrical shell will flutter. The results contribute to the design of reasonable structure parameters to avoid flutter. Finally, numerical simulations are also presented to demonstrate the good agreement with the analytical predictions. [ABSTRACT FROM AUTHOR]

Manipulating the ligand shell of semiconducting quantum dots (QDs) has proven to be a promising strategy to enhance their photocatalytic performance for small molecule transformations, such as H2 evolution and CO2 reduction. However, ligand-controlled catalysis for macromolecules, which differ from small molecules in penetrability and charge transfer behavior due to their bulky sizes, still remains undiscovered. Here, we systematically investigate the role of surface ligands in the photocatalytic performance of cadmium selenide (CdSe) QDs in light-induced atom transfer radical polymerization (ATRP) by using thiol-based ligands with various polarities and chain lengths. A highly enhanced polymerization efficiency was observed when 3-mercapto propionic acid (MPA), a short-chain and polar ligand, was used to modify the CdSe QDs' surface, achieving high chain-end fidelity, good temporal control, and a dispersity of 1.18, while also tolerating a wide-range of functional monomers ranging from acrylates to methacrylates and fluorinated monomers. Transient absorption spectroscopy and time-resolved photoluminescence studies reveal interesting mechanistic details of electron and hole transfers from the excited QDs to the initiators and 3-MPA capping ligands, respectively, providing key mechanistic insight of these ligand controlled and QD photocatalyzed ATRP processes. The thiolate ligands were found to serve as an efficient hole acceptor for QDs, which facilitates the formation of a charge-separated state, followed by electron transfer from the conduction band edge to initiators and ultimately suppressing charge recombination within the QD. [ABSTRACT FROM AUTHOR]

Targeted gene delivery to the brain is a critical tool for neuroscience research and has significant potential to treat human disease. However, the site-specific delivery of common gene vectors such as adeno-associated viruses (AAVs) is typically performed via invasive injections, which limit its applicable scope of research and clinical applications. Alternatively, focused ultrasound blood-brain-barrier opening (FUS-BBBO), performed noninvasively, enables the site-specific entry of AAVs into the brain from systemic circulation. However, when used in conjunction with natural AAV serotypes, this approach has limited transduction efficiency and results in substantial undesirable transduction of peripheral organs. Here, we use high throughput in vivo selection to engineer new AAV vectors specifically designed for local neuronal transduction at the site of FUS-BBBO. The resulting vectors substantially enhance ultrasound-targeted gene delivery and neuronal tropism while reducing peripheral transduction, providing a more than ten-fold improvement in targeting specificity in two tested mouse strains. In addition to enhancing the only known approach to noninvasively target gene delivery to specific brain regions, these results establish the ability of AAV vectors to be evolved for specific physical delivery mechanisms. Targeted gene delivery to the brain is a critical tool for neuroscience research and has significant potential to treat human disease. Here the authors engineer the protein shell of a common gene therapy vector for enhanced efficiency and specificity of brain delivery in ultrasound-targeted brain regions. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to investigate the nonlinear free vibrational characteristics of temperature-dependent two-directional functionally graded porous (TDFGP) cylindrical shells resting on elastic substrates in a thermal environment. To accomplish this, the thermomechanical equations are derived based on the Donnell nonlinear shell theory framework in conjunction with the von Kármán assumption. Two-directional functionally graded porous cylindrical shell models have mechanical properties that can change smoothly and continuously across the length and thickness of the shell. Additionally, it is assumed that the internal porosities in the matrix materials can be dispersed into two independent patterns, either even or uneven porosity distribution. The nonlinearity in free vibration assessed via the nonlinear-to-linear frequency ratio concerning the central deflection amplitude can be gained employing the Galerkin discretization approach and modified Poincare–Lindstedt (P-L) method. The accuracy and effectiveness of the present analytical model are indicated through comparison with existing solutions. Finally, some comprehensive parametric investigations are carried out to gain insight into the impacts of several factors on the nonlinear free vibration characteristics of structures under different conditions. The results of this article demonstrate that parameters such as gradient indices, volume fraction, distribution pattern of porosity, geometric parameters, and ambient temperature rise significantly influence the structure's nonlinear frequency and free vibration response. [ABSTRACT FROM AUTHOR]

Bimetallic core‐shell nanoparticles (NPs) possessing a synergetic coupling of plasmonic and catalytic metals have emerged as promising prototypes for efficient plasmon‐driven photocatalysis. Here, Au@AuPd core‐shell NPs composed of Au core NP and ultrathin AuPd shell are introduced to acquire improved light utilization efficiency in photocatalytic selective oxidation. With systematical control of the composition of the ultrathin alloy shell, it reveals that the Au@AuPd core‐shell NPs with 10 at% Pd (in the single‐atom alloy regime) is an effective nanostructure capable of maximizing the quantum yield of plasmon‐induced light absorption and optimizing the surface electronic structure for catalytic reactions. This controlled system provides new insights into shell engineering for enhancing photocatalytic performance via the regulation of energy funneling processes in core‐shell nanocatalysts. [ABSTRACT FROM AUTHOR]

The demand for lightweight, thin electromagnetic interference (EMI) shielding film materials with high shielding effectiveness (SE), excellent mechanical properties, and stability in complex environments is particularly pronounced in the realm of flexible and portable electronic products. Here, we developed an ultra-thin film (CNT@GC) in which the glassy carbon (GC) layer wrapped around and welded carbon nanotubes (CNTs) to form a core-shell network structure, leading to exceptional tensile strength (327.2 MPa) and electrical conductivity (2.87 × 105 S·m−1). The CNT@GC film achieved EMI SE of 60 dB at a thickness of 2 µm after post-acid treatment and high specific SE of 3.49 × 105 dB·cm2·g−1, with comprehensive properties surpassing those of the majority of previous shielding materials. Additionally, the CNT@GC film exhibited Joule heating capability, reaching a surface temperature of 135 °C at 3 V with a fast thermal response of about 0.5 s, enabling anti-icing/de-icing functionality. This work presented a methodology for constructing a robust CNT@GC film with high EMI shielding performance and exceptional Joule heating capability, demonstrating immense potential in wearable devices, defense, and aerospace applications. [ABSTRACT FROM AUTHOR]

The nonlinear buckling response of laminated composite cylindrical shells reinforced with graphene nanoplatelets (GNPs) is studied in this paper. The functionally graded (FG) shell reinforced by GNPs is analytically studied under external pressure and uniform temperature rise loadings. It is also assumed that the GNP-reinforced laminated composite shell is in contact with an elastic foundation. Various types of profiles are employed for the GNP distribution patterns in the shell thickness including 10 nanocomposite layers. The nonlinear strain-displacement relations of the shallow cylindrical panel are established utilizing the third-order shear deformation shell theory. Governing equilibrium equations of the laminated GNP-reinforced composite shell are formulated employing the principle of virtual displacement. The coupled system of nonlinear differential equations is solved analytically for the hinged–hinged and fixed–fixed boundaries of the shell using a perturbation-based technique. Correctness of presented formulations and obtained solutions is proved by comparisons with results from previous studies for an isotropic cylindrical shell. Novel numerical results reveal that the material properties, geometrical characteristics and load parameters significantly affect on the buckling behavior of laminated composite cylindrical shells. [ABSTRACT FROM AUTHOR]

Due to the excellent mechanical properties and strong design flexibility, the 3D woven composite engine casing shows great potential in high performance fields. This article adopted the method of double-layer weaving and adding yarn to achieve the variable thickness of the 3D woven composite engine casing. The purpose of this article is to study the compression performance and failure mechanism of this variable thickness casing in different thickness zones through experiments and numerical simulations to lay a foundation for future optimization and inclusiveness research on this casing with complex thickness changes. Three types of representative volume cells are established for progressive damage analysis. 3D-Hashin criteria and von-Mises stress criterion are used as damage criteria for yarns and matrix. The progressive damage process and the proportion of damage in the inner and outer layers of three types of 3D woven tubes under axial compression load are analyzed. Results show that the main failure modes of the three types of tubes are yarn-matrix compressive cracking along direction 3 and matrix failure. The damages are mostly concentrated in the warp bending area. The proportions of warp yarn damage in the inner and outer layers of three tubes are different. [ABSTRACT FROM AUTHOR]

Chinese ice-ray (IR) lattices, known for their intricate and visually fascinating random patterns as decorative elements in traditional 18th-century Chinese window design, exhibit underlying stiffness as latticed window fences. Such unique patterns represent a new morphology within the family of stochastic lattices. However, the latent structural potential within the random patterns of ice-ray lattices remains largely unexplored, particularly in the context of lattice shell design. This study systematically studies the geometric qualities of ice-ray lattice patterns and develops an algorithm to model these patterns for ice-ray lattice shell design. Subsequently, it assesses the structural feasibility and effectiveness of these lattice shells in comparison to conventional gridshells. The practicality of constructing random lattice shells using digital fabrication tools is also explored. Employing fractal geometry as a foundational framework, this research not only offers insights into the potential of ice-ray lattices for innovative lattice shell design but also introduces a new structural morphology to the field, expanding the possibilities of incorporating stochastic patterns in lattice shell design. Ultimately, it opens up new opportunities for innovative lattice shell designs, emphasizing the potential of stochastic patterns in structural applications. [ABSTRACT FROM AUTHOR]

As 5G technology advances, so does the prevalence of harmful electromagnetic waves, and as a result, researchers have been progressively interested in developing materials that can absorb microwaves. So, it's become desirable to fabricate unique microwave absorbent materials (MAMs) to mitigate the negative effects of electromagnetic radiation and offer protection to biological beings and electronic data. Herein, we fabricated a novel HoFeO 3 @WSe 2 @SiO 2 composite via the co-precipitation method. The microwave absorption properties of the HoFeO 3 ,WSe 2 , SiO 2 and HoFeO 3 @WSe 2 @SiO 2 (with 25, 35 and 45 wt% loading) were examined in the X-band frequency range. 35 wt% filler loading shows reasonable reflection loss values with the broadest effective absorption bandwidth (EAB). The optimum impedance matching is responsible for the enhanced microwave absorption performance of the HoFeO 3 @WSe 2 @SiO 2 with 35 wt% filler loading. In addition, the best sample is measured using both waveguide and free-space techniques and the results have been compared. The free-space method has been demonstrated to be an effective alternative testing strategy due to its contact-free and non-destructive features. Furthermore, the technique described in this study to design innovative HoFeO 3 @WSe 2 @SiO 2 microwave absorbers can offer significant assistance with a wider absorption band. In this context, HoFeO 3 @WSe 2 @SiO 2 is expected to be used as a highly efficient microwave absorbent. [ABSTRACT FROM AUTHOR]

The molecular structure of the type 1 human immunodeficiency virus (HIV-1) is tightly linked to the mechanism of viral entry. The spike envelope (Env) glycoproteins and their interaction with the underlying matrix (MA) shell have emerged as key components of the entry mechanism. Microscopy evidence suggests that the MA shell does not span the entire inner lipid surface of the virus, producing a region of the virus that completely lacks an MA shell. Interestingly, evidence also suggests that Env proteins cluster during viral maturation and, thus, it is likely that this event takes place in the region of the virus that lacks an MA shell. We have previously called this part of the virus a fusion hub to highlight its importance during viral entry. While the structure of the MA shell is in contention due to the unaddressed inconsistencies between its reported hexagonal arrangement and the physical plausibility of such a structure, it is possible that a limited number of MA hexagons could form. In this study, we measured the size of the fusion hub by analysing the cryo-EM maps of eight HIV-1 particles and measured the size of the MA shell gap to be 66.3 nm ± 15.0 nm. We also validated the feasibility of the hexagonal MA shell arrangement in six reported structures and determined the plausible components of these structures that do not violate geometrical limitations. We also examined the cytosolic domain of Env proteins and discovered a possible interaction between adjacent Env proteins that could explain the stability of cluster formation. We present an updated HIV-1 model and postulate novel roles of the MA shell and Env structure. [ABSTRACT FROM AUTHOR]

As the electronic industry develops rapidly, nowadays, flexible dielectric materials with excellent integrated dielectric performances including high dielectric permittivity (ɛ) and breakdown strength (Eb) but low loss, are highly pursued. In this work, to concurrently improve the ɛ and Eb but restrain the loss of original Si/polyvinylidene fluoride (PVDF) composites, the core@shell structured Si@SiO2 particles first were produced via high temperature oxidation process, and then incorporated into the PVDF to generate morphology-dependent composites with high-ɛ and Eb but low loss. The dielectric properties of the composites were investigated in terms of the filler types and concentrations, frequency, and theoretically fitted using the Havriliak-Negami equation to reveal the SiO2 shell' role in affecting the polarization mechanism. When compared to pure Si/PVDF at high filler loadings, remarkably inhibited dielectric loss and conductivity as well as enhanced Eb concurrently can be achieved in the Si@SiO2/PVDF composites still harvesting a high-ɛ. This is because the insulating SiO2 shell not only effectively prevents the raw Si particles from direct physical contact, but also greatly impedes the long-range charge carrier migration via raising energy barrier subsequently leading to obviously enhanced Eb. Moreover, the dielectric loss and conductivity apparently decrease with increasing the SiO2 shell thickness due to its pronounced suppression effect. The prepared Si@SiO2/PVDF with a high Eb and ɛ but low loss, show bright future uses in micro-electronic devices used for high-voltage purposes. [ABSTRACT FROM AUTHOR]

A semi-sealed cylindrical shell is a hollow cylinder in which one end is open and the other end is sealed. In order to systematically study the cavity evolution, the hydrodynamic characteristics, and corresponding structural response of the semi-sealed cylindrical shell during high-speed vertical water entry, a numerical simulation is carried out based on a Star-CCM+ and ABAQUS collaborative simulation method. The results show that a nested cavity is formed that presents three different morphologies as the semi-sealed cylindrical shell penetrates the water. Moreover, a jet is formed under the shell, which profoundly influences the hydrodynamic and structural characteristics. Compared with the completely sealed case, the velocity and displacement of the semi-sealed cylindrical shell are significantly changed upon water entry, and the deformation at the top wall is more prominent. [ABSTRACT FROM AUTHOR]

Most commercial products of dehulled hemp seeds frequently include dark green remnants of shells. The entire removal of shell particles including seed coats and pericarp pieces can improve the quality of hempseed-based products. In this study, the structural characteristics of fruit walls (pericarp) and seed coats of Cannabis sativa were examined using scanning electron microscopy. The pericarp was comprised of three distinct zones, exo-, meso-, and endocarp. The exocarp and the mesocarp were tightly fused to form a thick layer. The endocarp was characterized by its sclerenchymatous columnar cells, which contained greatly thickened and multi-porous cell walls. On the other hand, the seed coats were comprised of two leathery coats, the outer and inner coats. The outer seed coat was a conspicuous layer with a reticular-shaped structure like a net. However, the three-layered inner seed coat was composed of two thin layers (inner seed coat 2, inner seed coat 3) and a large rectangular cell layer (inner seed coat1) at the lower position. This work provides a better understanding of the structural characteristics of hemp shells. It will lead to the improvement of dehulling machinery of hempseed and help ensure stringent quality control of hempseed-based products. [ABSTRACT FROM AUTHOR]

Thin-shell structures are used in several fields of construction and are often exposed to severe dynamic environments, making them susceptible to dynamic instabilities. These instabilities are typically preceded by varying degrees of damage to the shell, justifying the need to incorporate this behavior in the formulation of the finite elements used. The objective of this work is to evaluate the different dynamic instability criterion in the presence of damage, afterward, evaluate the influence of this behavior on the stability of shells subjected to the dynamic excitations. The methodology of this project is essentially numerical, based on the finite element method. We are asked to program the introduction of damaging behavior and Lemaitre's model criteria in the DYNCOQ program developed locally. To examine the results, two examples extracted from the literature were presented. The first model aimed to confirm the proper functioning of the program and the convergence of the plasticity criterion (Lemaitre's model). As for the second model, it allows us to test the dynamic instability. A comparison was made with experimental data from previously published literature, revealing a strong agreement between the calculated and experimental results. The obtained results prove the utility of considering this behavior in the shell analysis. [ABSTRACT FROM AUTHOR]

Often contemporary buildings undergo several modifications during their life cycle, usually targeting the retrofitting of their inner or outer shell or the reinforcing of the structural system. A modular construction strategy often forms the solution for a quick and standardized production or modification of architectural spaces. The paper departs from the ambiguity by clarifying terms and strategies in modular construction to further discuss the typologies of modular architecture, the historical and theoretical context in which they have evolved and their design and construction process. Finally, it conducts a critical analysis and classification coupled with a study of structures that are formed by the synthesis of modules that have the same shape and size, to identify current trends and extract conclusions about the impact of modularity in architecture. [ABSTRACT FROM AUTHOR]

Background: Dynamic behaviour of composite materials under impact is a severe concern as it results in premature failure of the structural components. Most of the damages arising due to impact are undetected by visual inspection; therefore prediction of impact response is very crucial. Purpose: The existence of delamination reduces the strength and stiffness of the composite structures and enhances the damage phenomenon. The critical impact velocity at which the first-ply failure (FPF) and the associated transient response is a major engineering concern and needs significant attention. Methods: A finite element method (FEM) based investigation is carried out to analyse the dynamic response of delaminated cantilever composite conical shell impacted centrally at random points by a spherical impactor. An eight-noded isoparametric shell element is used based on Mindlin's shallow shell theory. The indentation laws proposed by Hertz are used to evaluate the contact force, displacement and identification of the failure zones. Newmark's time-integration scheme is used to obtain the dynamic response of the impacted shell. The Tsai-Wu failure criterion which is the most general and consistent criterion for biaxial stresses is used to predict the critical velocity of impact for first-ply failure initiation in composite conical shells. Results: Results include the effects of different parameters like size and number of delamination, aspect ratio, fibre-orientation angle and impact location on the dynamic behaviour of conical shell at maximum safe impact velocity beyond which first-ply failure will commence. Conclusions: On increase of the aspect ratio, size and number of delamination, the contact force, shell displacement, impactor displacement and the critical velocity at which the FPF initiates are found to decrease. When the impact location moves from near fixed end to near the free end, the contact force, shell displacement, impactor displacement and impactor velocity decreases. [ABSTRACT FROM AUTHOR]

The American lobster, Homarus americanus , H. Milne Edwards, 1837 is an ecologically, economically, and culturally valuable marine resource for the coastal communities in the Gulf of Maine. Lobsters in the Gulf of Maine are experiencing the effects of rapid warming and acidification due to climate change. Lobster shells are comprised of chitin with precisely precipitated minerals (calcite, amorphous calcium carbonate, and carbonate apatite) that provide structural integrity to the shell and protection against predators and microbial intrusion. We examined the combined effects of ocean warming and acidification on shell mineralogy, epibiont abundance, and growth in early benthic juveniles. Lobsters were grown under six different temperature/pCO2 treatment conditions over 52 days (three replicates per treatment) aligned with environmentally relevant as well as predicted future extremes. Elevated pCO2 and temperature led to a decrease in shell calcium and magnesium content, suggesting that these environmental stressors inhibit shell biomineralization. There was an interactive effect of the stressors on epibiont abundance with the probability of epibiont coverage increasing with increasing pCO2 and temperature. Elevated pCO2 alone was significantly correlated (P = 0.002) to decreased growth, but only for female lobsters. Ocean acidification and warming significantly affect shell integrity in juvenile lobster, increasing risk to injury and disease with potential downstream consequences for the lobster fishery. [ABSTRACT FROM AUTHOR]

The analytical solutions for buckling of closed and open cylindrical shells under different boundary conditions are challenging. A separation‐of‐variable method with closed‐form eigensolution under Donnell–Mushtari theory is proposed for eigenbuckling analysis in cylindrical shells. The modal function is adopted as the form W = eμαeλβ. It can be applied to the closed and open cylindrical shells with different boundary conditions, and the whole calculation process is explicit. The critical buckling capacities of short cylindrical shells are close under the simply supported or clamped boundary conditions. The predictions are in good agreement with those in literature and the finite element model. [ABSTRACT FROM AUTHOR]

Since waste materials are used to identify, individualize, and evaluate evidence like fingerprints, palmprints, footprints, etc. that are found at a crime scene, they have a substantial impact on the field of forensic science. Many waste powders have recently been employed in fingerprint recognition. Nanosheets made up of eggshells have been put forward as an application in friction ridge development. Eggshell is a biochemical substance made up of chemical compounds like calcium carbonate, which is considered as a waste product. For the formation of an eggshell nanosheet (ESN), shells are dried and crushed into a fine powder and to get this powder in the form of a nanosheet, the Ball milling technique is used. The synthesis of pure ESN is confirmed by Scanning Electron Microscopy (SEM) and X‐ray diffraction (XRD) techniques. The size of nanosheets ranged from 30 to 90 nm as shown in SEM images. Developed powder is then used for the application of fingerprint development and it provides excellent results on all porous, non‐porous, and semi‐porous surfaces. Thus, this newly synthesized ESN powder can be used as a significant powder method in latent fingerprint technology. [ABSTRACT FROM AUTHOR]

In this paper, dispersion properties of guided waves in multilayer composite cylindrical shells are studied, which is composed of the inner and outer hybrid nanocomposite (MHC) layers and the middle composite core layer reinforced with shape memory alloy (SMA) fibers. According to the Hamiltonian principle and the thermoelastic theory, wave equations of the composite structure at different ambient temperatures are derived and discretized with spectral elements. By combing the thermal effects and the acoustoelastic effects, the modified semi-analytical finite element method is proposed here for the thermo-acoustoelastic effects of wave characteristics in laminated composite shells. The influence of important parameters on the dispersion characteristics of the structure is explored. The results show that the coupling of SMA fiber reinforced composite layer and MHC layers can significantly improve wave propagation characteristics of the composite cylindrical shells. The frequency of modal conversion increases with the increase of CNT volume fraction. Smaller radius-to-thickness ratios are favorable for internal wave propagation in the structure. This work is of great significance for the regulation of elastic wave propagation in multilayered cylindrical shell structures, and provides a valuable guide for the design and optimization of shell structures in engineering applications. [ABSTRACT FROM AUTHOR]

During automobile crashes, the main behavior of plastics in the vehicle is bending deformation. Because of this, it is important to accurately calculate the edge stress and allowable stress on structural surfaces. For that purpose, it is necessary to consider the distribution of the fiber orientation angle and degree in the plate thickness direction. In a general coupled analysis for injection-molded materials, a material model is created based on the physical properties obtained from an arbitrary test piece. Therefore, even if the orientation angle in each part to be analyzed is taken into consideration, the degree of orientation is constant in each part, and the degree of orientation distribution in the plate thickness direction is also treated as constant. We tried to improve the accuracy of crash analysis by calculating the edge stress and allowable stress with high accuracy by considering the distribution of orientation angle and degree in the plate thickness direction. For that purpose, we created a model that calculates properties of composite materials from resin and fiber properties, and a process that maps the distribution of orientation angle and degree in the plate thickness direction to each integration point of the shell element in structural molding analysis. [ABSTRACT FROM AUTHOR]

An investigation is performed in this paper to analyze the nonlinear thermo-electro-mechanical response of long sandwich cylindrical shells with functionally graded porous (FGP) core and thin piezoelectric actuator layers. The FGP core of the sandwich shell is assumed to be temperature- and microstructure-dependent. It is assumed that the sandwich shell is subjected to uniform lateral pressure loading in a thermo-electrical environment. The equilibrium equations of the shell with infinite length are established with the aid of the virtual displacement principle and von Kármán kinematic assumptions. The governing equations are obtained in terms of displacement components based on the first-order shear deformation model of shallow cylindrical shells and the modified couple stress theory. These nonlinear differential equations are analytically solved for a sandwich shell having both the simply-supported and clamped–clamped edge conditions by employing a two-step perturbation technique. Analytical closed-form solutions are determined as a relationship including the load parameter and the mid-span deflection. The comparison examples are made with the existing results in the literature for a simple functionally graded shell, where good agreement is obtained. It is shown that the nonlinear response of the sandwich shell is highly dependent upon the temperature variation, power law index, porosity coefficient, couple stress parameter, piezoelectric layers, and geometrical parameters of the shell. [ABSTRACT FROM AUTHOR]