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Photonic crystals can be used to achieve high‐performance surface‐emitting lasers and enable novel photonic topological insulator devices. In this work, a GaAs/InGaAs heterojunction nanowire platform by selective area metalorganic vapor phase epitaxy for such applications is demonstrated. The nanowires are arranged into deformed honeycomb lattices on silicon‐on‐insulator substrate to exploit the quadrupolar photonic band‐edge mode. Core–shell and axial heterostructures are formed with their crystalline properties studied by scanning transmission electron microscopy. Room‐temperature, single mode lasing from both stretched and compressed honeycomb lattices within the telecom‐O band, with lasing threshold as low as 1.25 µJ cm−2 is demonstrated. The potential of using InGaAs nanowire‐based honeycomb lattices for small‐divergence surface‐emitting lasers and topological edge mode lasers is investigated. Finite‐difference time‐domain far field simulations suggest a sub‐10° beam divergence can be achieved thanks to the out‐of‐plane diffraction. [ABSTRACT FROM AUTHOR]

Sandwich structures with good mechanical performance can be manufactured by continuous carbon‐fiber‐reinforced composites (CCFRC) via the fused filament fabrication (FFF) technology. Poor inter‐thread bonding is a major reason for the failure of these sandwich structures. In the present study, a novel fiber‐interleaved printing pattern has been proposed to improve the bonding property between printing threads. And panel/core integrated sandwich structures were fabricated via the FFF technology. The manufacturing quality was examined by microscopic examination and non‐destructive computed tomography (CT) scanning. The results indicated that manufacturing voids are mainly concentrated in the printed carbon fiber bundles, resulting from inadequate infiltration between the reinforcement and the matrix. Flatwise compression tests were conducted to compare the mechanical performance of sandwich structures with the fiber‐adjacent and fiber‐interleaved core. The results clearly demonstrated that the fiber‐interleaved design can significantly improve the mechanical performance of the sandwich structures (i.e., 44% higher in elastic modulus and 119% higher in strength). Furthermore, three‐point bending tests were conducted to investigate the flexural behavior. Fractographic analysis demonstrated that the main failure modes under these loading conditions include fiber pull‐out and breakage, delamination, local core crushing, fiber/matrix and panel/core debonding. [ABSTRACT FROM AUTHOR]

The design freedom provided by additive manufacturing offers new opportunities to fabricate novel structures with a high lightweight potential, such as strut‐based lattice structures. These lattice structures consist of periodically repeated unit cells and can be used in several applications due to their outstanding mechanical performance. One of the possible applications are cores of sandwich panels since the strut‐based lattices offer comparable mechanical properties to conventional honeycomb structures. Moreover, multifunctional use of the sandwich core is enabled by allowing the heat and fluid transfer through the sandwich due to the open‐celled lattice structure. However, strut‐based lattices are rarely utilized as cores in sandwich panels in engineering practice. One of the main reasons for that is the unknown mechanical behavior of lattice cores. In particular, when the sandwich is subjected to concentrated loads, localized stresses and deformations occur in the sandwich core, leading to core damage. In this work, we present a novel analytical model to determine stresses and deformations in the struts of lattice cores of sandwich panels using homogenization and dehomogenization methods. The local core compression caused by localized transverse forces can also be determined by the derived model. [ABSTRACT FROM AUTHOR]

Indirect lightning strikes hitting near photovoltaic installations are much more frequent than direct hits, and can generate overvoltage in their electric circuitry. The authors developed a method to estimate the induced overvoltage on single photovoltaic modules. Using a model of the whole array also including Inter‐Module Coupling Mechanisms (IMCMs), a new approach to estimate overvoltage induced on full arrays is presented in this paper. The procedure first estimates lumped parameters, modelling either the coupling between the lightning channel and each module in the array or between each couple of modules in array. Several circuital simulations are then run using suitable equivalent circuits. The aim is to consider different array configurations and groundings schemes. This allows extracting the most relevant configuration parameters influencing overvoltage/overcurrent. Results show that the groundings scheme impacts negligibly, but the single module electric stress is decreased by 35% in the case of ungrounded configurations. Among the considered array configurations, the honey‐comb and total cross‐tied showed the smallest impact on overvoltage. Statistical analysis on random LC tortuous geometry leads to a non‐negligible rise of overvoltage peak values, up to 24%. Finally, the relevance of different IMCMs is analysed, showing a strong impact just on frame‐ground voltages and currents. [ABSTRACT FROM AUTHOR]

The on‐surface self‐assembly of molecules to form holey nanographenes is a promising approach to control the properties of the resulting 2D lattice. Usually, planar molecules are utilized to prepare flat, structurally confined molecular layers, with only a few recent examples of warped precursors. However, control of the superstructures is limited thus far. Herein, we report the temperature‐controlled self‐assembly of a bowl‐shaped, acetylated C3‐symmetric hexaphenyltribenzotriquinacene derivative on Cu(111). Combining scanning tunneling microscopy (STM) and density functional theory (DFT) confirms the formation of highly differing arrangements starting with π‐stacked bowl‐to‐bowl dimers at low coverage at room temperature via chiral honeycomb structures, an intermediate trigonal superstructure, followed by a fully carbon‐based, flattened hexagonal superstructure formed by on‐surface deacetylation, which is proposed as a precursor for holey graphene networks with unique defect structures. [ABSTRACT FROM AUTHOR]

MoP@C nanocomposite, combined three‐dimensional (3D) honeycomb carbon matrix with molybdenum phosphide, was synthesized through a simple hard template method followed by high‐temperature phosphating treatment. The MoP@C has shown excellent sodium and potassium‐ion storage properties applied as anode materials for sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs). The MoP@C composite maintains a high reversible specific capacity of 250 mAh g−1 in SIBs after 100 cycles at 0.5 A g−1. Furthermore, even at a high current density of 5 A g−1, it still delivers a specific capacity of 200.5 mAh g−1. Additionally, the nanocomposite holds 147.2 mAh g−1 at a high current density of 1 A g−1 in PIBs. The excellent electrochemical performance benefits from the synergistic effect of the hierarchical MoP@C nanostructure. The exquisite porous nano‐frame with higher conductivity and larger specific surface area, the active substance is fully infiltrated in the electrolyte, and successfully shortens the diffusion distance of electrons and ions. Moreover, the cavity in the heterostructure effectively inhibits the instinctive aggregation of MoP and simultaneously alleviates the volume expansion during the intercalation and deintercalation of ions in the charge and discharge process, enabling the excellent rate performance and long cycle life of the MoP@C electrode. The designed MoP@C composite shows excellent electrochemical cycle performance and rate performance as anode materials for sodium/potassium‐ion batteries. The MoP@C composite maintained a high reversible specific capacity of 250 mAh g−1 in sodium‐ion batteries after 100 cycles at the current density of 0.5 A g−1. Furthermore, even at a high current density of 5 A g−1, it still delivered a specific capacity of 200.5 mAh g−1. Moreover, MoP@C composite materials also show excellent performance as anode material of potassium‐ion batteries, with a specific capacity of 147.2 mAh g−1 at the high current density of 1 A g−1. In summary, the excellent electrochemical performance of MoP@C composite materials fully proves that they can greatly improve the stability of the structure and reversibility as electrode materials, and lays a foundation for the further application of electrochemical energy storage devices in large‐scale applications. [ABSTRACT FROM AUTHOR]

Optimizing renewable energy harvesting is of major importance in the following decades. In order to increase performance and efficiency, an ideal balance of mechanical and piezoelectric properties must be targeted. For this purpose, the approach of ceramic auxetic and honeycomb structures made of (Ba,Ca)(Zr,Ti)O3 (BCZT) which is produced via injection molding is considered. The main design parameter is the structural angle θ which is varied between −35° and 35°. Its effect on compressive strength, Young's modulus, and Poisson's ratio are determined via uniaxial compression tests and digital image correlation (DIC). Maximum compressive strength of 95 MPa at 0° (porosity of 59%) is found, which is superior to conventional porous ceramics of the same porosity. The piezoelectric constants d33 (max. 296 pC N−1) and g33 (max. 0.068 Vm N−1) are measured via the Berlincourt method and also exceed expectations, regardless of the structure. The theoretical models of Gibson and Ashby (mechanical) and Okazaki (piezoelectrical), as well as finite element method simulations, strengthen and explain the experimental results. [ABSTRACT FROM AUTHOR]

The on‐surface self‐assembly of molecules to form holey nanographenes is a promising approach to control the properties of the resulting 2D lattice. Usually, planar molecules are utilized to prepare flat, structurally confined molecular layers, with only a few recent examples of warped precursors. However, control of the superstructures is limited thus far. Herein, we report the temperature‐controlled self‐assembly of a bowl‐shaped, acetylated C3‐symmetric hexaphenyltribenzotriquinacene derivative on Cu(111). Combining scanning tunneling microscopy (STM) and density functional theory (DFT) confirms the formation of highly differing arrangements starting with π‐stacked bowl‐to‐bowl dimers at low coverage at room temperature via chiral honeycomb structures, an intermediate trigonal superstructure, followed by a fully carbon‐based, flattened hexagonal superstructure formed by on‐surface deacetylation, which is proposed as a precursor for holey graphene networks with unique defect structures. [ABSTRACT FROM AUTHOR]

Accelerating the curing of epoxy/aromatic amine adhesives and improving their toughness are challenges in heat‐resistant epoxy structural adhesives. Herein, we report an epoxy/aromatic amine adhesive accelerated curing system with an oxo‐centered trinuclear (chromium III) complex, which is toughened using a thermoplastic block copolymer (TPBC). The reaction characteristics, heat resistance, microstructure, and bonding properties of the accelerated epoxy adhesives were analyzed. The reaction peak temperature of the epoxy with 3% catalyst was 113.1°C, which was 113.6°C lower than that of epoxy without catalyst, and the modified epoxy resin demonstrated a potential for rapid curing at medium temperature. The glass transition temperature of the TPBC‐toughened epoxy adhesive was 125°C after curing, indicating excellent thermal stability after medium temperature curing. The introduction of the TPBC increased the single‐lap shear strength of the epoxy adhesive without reducing its heat resistance. The shear strength at room temperature and 120°C of the modified epoxy adhesive with 50 phr of TPBC was 25.2 and 10.9 MPa, respectively. Moreover, the epoxy film adhesive exhibited outstanding bonding properties when used in the bonding of lightweight honeycomb sandwich structures. [ABSTRACT FROM AUTHOR]

Porous materials have been widely used for passive energy absorption in various applications including aerospace systems, automotive vehicles, and electronic products, due to high energy dissipation and sound absorbing mechanism in a wide frequency band. However, most porous materials have a critical problem in poor mechanical properties that inhibit their application to shock absorbing structures. Herein, a multi‐purpose auxetic structure is reported that has a highly ordered honeycomb concave micropattern on the surface of the auxetic foam through non‐solvent induced phase separation. Most importantly, the dimensions of the concave micropatterns can be easily controlled depending on the non‐solvent ratio. The energy absorption performance and mechanical strength are significantly enhanced by adopting concave micropatterns on the curved surface in the auxetic foam. The superior energy absorption performances of the multi‐dimensional auxetic foam are improved by 37.5% in view of an average sound absorption coefficient, and the improved mechanical properties are verified by systematically investigating porous properties such as tortuosity, porosity, apparent density, and total pore area. In addition, the proposed multi‐purpose auxetic foam exhibits a remarkably improved shock energy dissipation capacity, which reduces impact force by 34% compared with that of bare polyurethane foam in a low‐velocity impact test. [ABSTRACT FROM AUTHOR]

To avoid the narrow absorption bandwidth and delamination in uniform honeycomb composites, three‐dimensional (3D) gradient honeycomb composites were prepared through a vacuum‐assisted resin transfer molding (VARTM) process. The 3D gradient honeycomb woven composite (3D GHWC) was made by using 3D gradient woven fabric with basalt and carbon fibers as reinforcement and epoxy resin mixed with carbon black and carbonyl iron powder as the matrix. For further optimization of the effective absorbing bandwidth and/or reflection loss (RL), especially at a specific incident angle, the type of absorbing agent and gradient honeycomb structure could be altered in the weaving process. The minimum RL value achieved by the 3D GHWC with 18.5‐mm thickness is −47 dB in the C band at a 30° incident angle using an Agilent vector network analyzer. In addition, the bending strength of the 3D GHWC with 18.5‐mm thickness reaches 101.7 MPa by a universal testing machine, which suggests excellent mechanical properties and ultra‐strong environmental adaptability of the 3D GHWC material. This work offers an adjustable method for the fabrication of microwave absorption (MA) composites, showing potential prospects in civilian and military MA applications. [ABSTRACT FROM AUTHOR]

The interlocked composite honeycomb structures have high specific strength and specific stiffness, convenient processing, and low cost with great application potential in aerospace, marine, construction, and civil fields. In this study, an effective method is proposed for manufacturing an all‐composite interlocked triangular honeycomb (CITH), and the quasi‐static mechanical properties of the honeycomb and the corresponding sandwich structure (CITHSS) are examined. Through experimental tests, the basic mechanical properties of CITH and CITHSS are analyzed. Further, the effective strength and stiffness coefficient of the slotted carbon sheets constituting CITH are measured through tensile experiments. The in‐plane stiffness model of CITH is derived based on the continuous equivalent method. The failure strength models of CITHSS are also established. At the same time, the failure modes under three‐point bending and edge compression loads are predicted. The experimental results reveal that compared with the interlocked Kagome and square honeycomb, the specific strength of CITH is increased by 27.8% and 24.4%, respectively. Further, the specific stiffness is increased by 148.4% and 8.3%, respectively. Compared with aluminum honeycomb sandwich, the compressive and bending specific strengths of CITHSS are increased by more than 46.5% and 15.2%, respectively. The debonding failure and edge effect are found to be the main weakness of CITHSS. Overall, CTIH and CITHSS exhibit excellent mechanical properties and create feasible options for processing complex multifunctional composite honeycombs by interlocking technology. [ABSTRACT FROM AUTHOR]

The impact resistance of the Nomex honeycomb sandwich structure subjected to strong dynamic loading of lightweight and deformable projectiles was studied experimentally. The deformation process and failure modes of the sandwich panels were investigated by using a first‐state gas gun to launch aluminum foam projectiles. 3D‐DIC was presented to investigate the dynamic response in terms of response rate and deflection‐profile history. And the impact resistance of three structures, namely single‐layer sandwich, rubber‐honeycomb sandwich and double‐layer sandwich, was compared in relation to the load intensity. The results show that the dynamic response process of the sandwich panel can be divided into discrete deformation stage, concentrated deformation stage，elastic stage, vibration stage and stabilization stage. As the impulse increases, the maximum deflection of the back face‐sheet continues to increase. Under the strong load of a light and deformable projectile, both rubber‐honeycomb and double‐layer honeycomb sandwich structures can effectively reduce the deflection change of the back face‐sheet and improve the load‐bearing capacity of the structure. Qualitatively analyzing the relationship between structure, loading, and performance can be carried out to provide guidance for structural design. [ABSTRACT FROM AUTHOR]

Considerable literature has studied different techniques to improve the thermal performance of latent heat thermal energy systems (LHTES) that utilize phase change materials (PCMs). This study aims to contribute to this growing area of research by using honeycomb structure and exploring the effect of heat transfer fluid (HTF) configuration and honeycomb cell angle on the thermal performance of the LHTES during melting and solidification processes. In this work, five cases were designed: case (a) was regarded as reference case; cases (b) and (c) were related to HTF configuration; cases (d) and (e) were used to study the effect of honeycomb cell angle. A numerical study was conducted using ANSYS FLUENT R19.3, followed by experimental validation. In this study, a good agreement is obtained from the validation process. Computational fluid dynamics (CFD) model results show symmetrical melting and solidification behavior when using a honeycomb structure. The results of the HTF configuration show a significant effect. For case (c) with a multiple water block, significant melting and solidification enhancements are obtained with 56% and 50%, respectively. Thus, the HTF configuration can improve the thermal performance of the storage. However, considering different honeycomb cell angles show an insignificant effect on the melting and solidification rates. [ABSTRACT FROM AUTHOR]

Strength and toughness are two vital and contradictory properties, especially in alumina structural ceramics. This mutual exclusion limits the widespread application of advanced alumina ceramics in harsh environments. To deal with this issue, self‐toughening alumina bulk ceramics without any ductile phase and with a unique combination of excellent toughness and reliable strength by combining the foam ceramics with hot‐pressing sintering are prepared. Foam ceramics with honeycomb cellular structures are prepared by particle‐stabilized foaming. Then, the foam ceramics is directly hot pressed sintered, in which the cellular structure is fractured into fragments and completely dense under pressure. Equiaxed grains that constituting the fragments grow anisotropically into plate‐like grains with a large diameter–thickness ratio during hot‐pressing sintering. Plate‐like grains improve the material's fracture toughness by exerting a toughening mechanism similar to that of fibers. The self‐toughening alumina ceramics exhibit a unique combination of high flexural strength (874 ± 31 MPa) and high fracture toughness (6.2 ± 0.1 MPa m1/2). The Vickers hardness also can reach 21 GPa. Herein, a new strategy with relatively simple processing to fabricate high‐performance ceramics based on the widespread ceramic processing techniques are provided. [ABSTRACT FROM AUTHOR]

Microchannel cooling technology has been proven to be extraordinarily efficient for the removal of heat flux in electronic devices. Here, we numerically investigate the thermal and hydraulic characteristics of microchannels with different shapes of ribs, namely, circular ribs, square ribs, regular ribs, and hierarchical honeycomb ribs. Those ribs are composed of solid and porous media. Results indicate that heat transfer can be promoted by adding different shapes of ribs. Especially, microchannels with hierarchical honeycomb ribs possess the greatest heat transfer capability. Pressure drop (Δp) and friction factor (f) display the largest values when microchannel ribs are hierarchical honeycomb and solid, whereas Δp of the microchannel with hierarchical honeycomb porous ribs dramatically decreases, which achieves an 81.1%–81.7% reduction. Results of j/f show that the microchannel with hierarchical honeycomb porous ribs presents the best comprehensive performance, which is ascribed to the superior heat transfer capability and the low Δp induced by the ultra‐hydrophobic effect. [ABSTRACT FROM AUTHOR]

The decorated honeycomb lattices (DHLs) represent a typical model that evinces nontrivial chiral spin liquid and rich topological insulating phases in condensed matter physics, yet in natural materials such lattice structures are not commonly found. Here, a photonic DHL that exhibits two singular flat bands is experimentally demonstrated, thereby observing two distinct robust boundary modes (RBMs) associated with each flat band. These RBMs rely on specially tailored open boundaries in the flatband lattice with wavefunction singularities due to band‐touching, manifesting topological noncontractible loop states that cannot be simply constructed from superposition of conventional flatband states. The robustness of such boundary modes to perturbations is also examined, corroborated by numerical simulations and theoretical analysis. This work illustrates a photonic platform exhibiting Dirac cones, singular band‐touching and multiple flat bands that may be employed to study exotic flatband phenomena and topological insulating phases in optics and beyond. [ABSTRACT FROM AUTHOR]

For a policy of 100% renewable energy, most renewable‐energy research is aimed at decarbonization; particular emphasis is being placed on increasing the portion of electricity generated by photovoltaics (PVs). As the application fields of PVs broadens from PV power plants and rooftop to various urban environments, achieving high energy yields requires expansion beyond current PV module structures. To satisfy these demands, honeycomb‐structured PV modules with incorporated mechanical metamaterials are proposed, to overcome the aforementioned problems associated with the limited mechanical properties of PVs, and to advance the development of 3D PV modules with enhanced energy yield. The honeycomb structures provide 28% greater power compared with flat cells by utilizing extra reflected or scattered light inside a 3D tetrahedron structure. For mechanical robustness, the 3D concave tetrahedron units are supported by a 3D‐structured mechanical metamaterial that exhibits a negative Poisson's ratio and is arranged in a 3D pattern. [ABSTRACT FROM AUTHOR]

The composite re‐entrant honeycomb structures were fabricated by hot pressing and bonding processes in this article. The bending responses of composite re‐entrant honeycomb structure under three‐point bending load were studied experimentally. The bending deformation, failure process and failure load were analyzed and discussed. The influence of wall thickness gradient form which were less reported on the bending behaviors of composite re‐entrant honeycomb structures was investigated. The gradient distributions included positive gradient, negative gradient and homogeneous structures. The experimental results indicated that the wall thickness gradient design influenced the bending failure modes of composite re‐entrant honeycomb structures, and the negative gradient honeycomb structure mainly exhibited the whole bending deformation under three‐point bending loading. The influence of the relative densities on the bending behaviors of composite re‐entrant honeycomb structures was also studied. The results of three‐point bending experiment showed that the bending failure load increased significantly with the increase of relative density. [ABSTRACT FROM AUTHOR]

Polymer‐filled honeycomb composites are composite materials that exhibit effective in‐plane moduli greater than either the honeycomb or polymer alone. Previous numerical modeling work by the authors has identified two key mechanisms by which this stiffness amplification is achieved. For thin honeycomb cells, the difference in Poisson's ratio between the infill and honeycomb drives the in‐plane composite behavior. For large cell depths, the volume change of the hexagonal cells, acting on the infill polymer, is the dominant factor in stiffness amplification. This work aims to extend these findings to thick walled honeycombs, and to experimentally validate the model predictions while making comparisons to existing analytic models. A unit cell finite element model is created for the composite, with isotropic material properties for the honeycomb and infill obtained from characterization tests on 3D printed honeycomb wall material and polyurethane elastomer infill materials. An experimental investigation is completed, where both empty and polymer filled honeycomb samples are 3D printed and tested for a range of cell geometries, varying the cell angle, cell depth, and infill polymer, and are testing in two in‐plane loading directions. The results support both the model predictions of the effective Young's moduli and the mechanisms of stiffness amplification previously found, with a maximum percent error of 16.9% found and an amplification factor of the infill modulus of up 16 demonstrated. The improved understanding demonstrated in this work supports the use of these composites in applications where reinforcement of the honeycomb by a polymer, or vice versa, is desired. [ABSTRACT FROM AUTHOR]

The efficiency of air separation is tested using three different small‐scale cryogenic distillation columns. The performance of a random packed column is compared to the performance of two microchannel distillation (MCD) columns that use thin wicking structures and gas flow channels to achieve process intensification. The MCD columns tested include a plate‐type layered column and an additively manufactured porous honeycomb (AMPH) column. For columns with 25.4 cm of active height and run under similar conditions, the packed, plate‐type layering, and AMPH columns achieved approximate height equivalent of a theoretical plate (HETP) values of 5.5, 3.7, and 3.2 cm for nitrogen, and 5.9, 4.9, and 3.3 cm for argon. The AMPH column can produce up to 0.4 SLM of more than 90% purity oxygen with 12 W of cooling lift. These results demonstrate the feasibility of using additive manufacturing to construct MCD devices and pave a way for constructing novel MCD designs. [ABSTRACT FROM AUTHOR]

In order to realize high recovery stress and large recoverable compression strain, by drawing inspiration from the bow‐and‐bowstring principle, we designed the temperature switch and actuator separately to reduce the response temperature when the shape recovers, thereby improving the storage modulus of the actuator and recovery stress. Meanwhile, a self‐template method was used to synthesize shape memory polymer (SMP) which has an actuator with a honeycomb structure to further improve the recovery force. Compared with the loofah‐like interpenetrating network structure SMP (SMP‐L) obtained using the traditional method, the SMP with a honeycomb‐like actuator (SMP‐H) has three times higher recovery stress than SMP‐L. SMP‐H can lift loads more than 400 times its own weight and has three times higher recovery lifting stress than SMP‐L. SMP‐H also has self‐healing, reprocessing, and recyclable properties due to its special honeycomb‐like actuator. This new synthesis strategy could provide opportunities for the wider application of SMPs. [ABSTRACT FROM AUTHOR]

Achieving bandgaps and double negative properties with single‐phase metamaterial in the low‐frequency range remains a challenge. Currently, acoustic metamaterials with double negative parameters are made of different materials, which can limit their application and design. Herein, a single‐phase multiple re‐entrant star‐shaped honeycomb (MRSSH) is designed and the double negative parameters and bandgaps are simulated. The numerical results show that the MRSSH exhibits three bandgaps and double negative characteristics (negative effective mass density and negative effective modulus) within a certain frequency range. The formation mechanics of bandgaps are investigated by analyzing the vibration modes. Moreover, the effects of geometry parameters such as internal concave angle and re‐entrant on the bandgaps and vibration modes of the MRSSH are investigated. By adjusting the geometry parameters, the dispersion curves and bandgap distribution can be tuned simultaneously. This study provides a new idea for designing a single‐phase lightweight metamaterial that can apply to noised reduction, vibration control, and super‐resolution imaging. [ABSTRACT FROM AUTHOR]

Auxetic metamaterials possess superior properties and have drawn extensive attention in the past decades. Herein, two curved ribs are added to the conventional re‐entrant (CRE) honeycomb structure to form a modified auxetic re‐entrant (MRE) honeycomb structure for improving the energy absorption capacity of the structure. In‐plane quasi‐static compression response of the honeycomb in large deformation is numerically explored first. Then, quasi‐static compression test is conducted to verify the validity of the numerical simulation. Both experimental and numerical simulation results reveal that during the quasi‐static compression process, two plateau stresses occur in the load–displacement curves of the structure, and the second plateau stress is much higher than the first one. The occurrence time of the second plateau stress can be controlled by the distance between the concave curved ribs in the structure. The experimental results are in good agreement with the finite element analysis results. Due to their desirable mechanical properties, the MRE honeycomb structures have great potential for applications in civil engineering, vehicle crashworthiness, and protective infrastructure. [ABSTRACT FROM AUTHOR]

Designing aramid nanofiber (ANF) aerogel with excellent microstructure and high thermal insulation property is benefit for applications in integrated thermal management system. To obtain a structurally controllable ANF‐based aerogel, the cellulose nanofiber (CNF) and poly (vinyl alcohol) (PVA) were 'stiff–soft' synergistic to improve the microstructure. The cobweb like structures distributed in the honeycomb layered pores of the CNF/PVA/ANF composite aerogel which was conducive to the performance and application of composite aerogel. The resulting CNF1/PVA1/ANF composite aerogels are highly porous (99.12%) and tiny volume shrinkage (4.65%), leading to excellent thermal insulation performance (26.83 mW/m·K). The 'stiff–soft' feature endows the composite aerogels high flexibility as well as large compression strength. These favorable multi‐features make the CNF/PVA/ANF composite aerogels ideal advanced material for aerospace, industrial, and commercial applications. [ABSTRACT FROM AUTHOR]

In order to prepare a cushioning composite with good resilience and compressibility, the 3D fabric was perforated into a hexagonal honeycomb, high elasticity porous polyurethane foam was used as substrate, and the air layer structure was encapsulated with the packaging film. By changing the hexagonal side length and wall thickness of the honeycomb structure, the integral fabric air layer polyurethane buffer composite was prepared. The properties of the structure were studied, and its compressive capacity under different compressive strains was analyzed. The results show that the mechanical properties of polyurethane foam were improved after adding the integral fabric air layer structure. When the composite HPU‐R1L2 (polyurethane cushioning composites with 1 cm side length and 2 cm wall thickness of hexagonal honeycomb) was compressed to 75%, its compressive capacity was 8.24 times that of PU (Polyurethane foam with 2.5% bentonite). The prepared composite HPU‐R1L1 (Polyurethane cushioning composites with 1 cm side length and 1 cm wall thickness of hexagonal honeycomb) absorbed 96.7% of the energy in the dynamic impact test, indicating that the composite cushioning performance was stronger than that of polyurethane foam. The HPU composites based on the synergistic reinforcement strategy of polyurethane foam and monolithic fabric air‐layer structures are an excellent candidate in the field of commodity packaging and personal protection. [ABSTRACT FROM AUTHOR]

The breath figure (BF) method is a handy strategy to prepare porous films. Linear shape memory polyurethanes (SMPUs) are among the most promising polymers for bone repair or regeneration. However, little attention has been paid to the fabrication of SMPU films by using the BF method. In this work, an amorphous SMPU containing isosorbide (ISO) in the long‐chain hard segments (ISO2‐PU) is fabricated into honeycomb porous films. Strikingly, a peculiar crystalline structure with a "Z" configuration and highly regional orientation is formed on the hexagonal holes of the porous films, which results in significantly enhanced mechanical properties. Moreover, the ISO2‐PU honeycomb porous films can markedly accelerate the osteogenic differentiation of rat mesenchymal stem cells, indicating that the porous films have great potentials as bone repair materials. It is further speculated that the Marangoni effect in the condensed water droplets and the molecular assembly of ISO2‐PU due to the strong hydrogen bonds and the chiral center effect of ISO are key contributors. This work, to the best of authors' knowledge, is the first time that this special crystalline structure on BF‐based porous films is observed and also the first speculation that combines Marangoni effect with the microstructure of BF‐based porous films. [ABSTRACT FROM AUTHOR]

Additive manufacturing (3D printing) offers new opportunities to create complex structures for many applications. The development of suitable precursors for high‐resolution 3D printing of ceramics is increasingly essential to meet evolving material requirements. Herein, a new hybrid preceramic formulation based on thiol‐ene click chemistry for precision printing of polymer‐derived ceramic has been developed to enable the fabrication of complex 3D objects using high‐resolution projection microstereolithography (PμSL). Two low‐odor thiol compounds with either three (trithiol) or four thiols (tetrathiol) moieties have been examined, to investigate the influence of thiol structure on the mechanical properties of converted ceramics. Pyrolysis of the printed green bodies leads to the formation of silicon oxycarbide (SiOC) with high fidelity after polymer‐to‐ceramic transformation. The SiOC printed specimen converted from the tetrathiol formulation (4T) demonstrates excellent mechanical strength surpassing that of the trithiol‐based formulation (3T) and previously reported SiOC preceramic polymers. The ceramic honeycomb fabricated using the tetrathiol compound shows remarkable improvement in compressive strength, which is two times higher than that of the trithiol‐derived ceramic. This work proposes a simple and effective way to formulate 3D printable preceramic polymers through molecular design. The achieved 3D printed SiOC can fulfill the requirement for high‐strength ceramic materials with complex shapes. [ABSTRACT FROM AUTHOR]

Recent advances in the development of flexible electronic devices have increased the demand for flexibility and conductivity. However, there is still a significant challenge to manufacture flexible electrodes featuring satisfactory mechanical and conductivity performance simultaneously. In this paper, based on synergistically combining theoretical structural design and screen printing, a new flexible electrode with butterfly‐shaped honeycomb (BSH) negative Poisson's ratio (NPR) structure through combining honeycomb and butterfly pattern bio‐inspired structure is designed and fabricated. And the flexibility and conductivity of different substrate electrodes are investigated. Results demonstrate that flexible electrode of polyamide (PA) substrate with BSH‐NPR structure can effectively boost the conductivity during the large deformation process, resulting in higher bending‐resistant (the resistance is only 4.1 Ω at 180°), fatigue‐resistance (only 4.5 Ω after 1000 cycles), stretching‐resistance (only 20.3 Ω at 20% strain), and self‐recovery (releasing strain enables re‐joining, namely, conductive) properties. Particularly, the electrode is still conductive when the strain of that is 40% and shows promising mechanical properties. Electrocardiography (ECG) signals recorded on the volunteer's chest, fingertips (no bending), and knuckles (repeated bending) are successfully exhibited with superior accuracy and long‐term stability for flexible electrode fabricated in this paper, demonstrating greater potential in biological signal monitoring applications. [ABSTRACT FROM AUTHOR]

The facile construction of 3D porous film using the breath figure technique is critically important in diverse practical applications. However, the discovery of easy synthetic methods and preparation of stimuli‐responsive 3D ordered nano‐/micro‐architectures remain challenging. Herein, the promotive breath figure technique is presented to construct 3D honeycomb porous films on curved substrates using an azobenzene‐containing copolymer. The nanopore size of honeycomb structure decreases gradually with the increase of surface curvature, due to the different solvent drying speeds. Upon irradiation with directional linear polarization light, the round‐shaped nanopores are converted into rectangular‐ and rhombic‐shaped nanopores under different polarization directions. Moreover, these porous films are employed as substrates to load various metal nanoparticles, successfully preparing the nanocomposites. The catalytic capacity of both control and these nanocomposites are evaluated using the NaBH4‐mediated reduction reaction from 4‐nitrophenol to 4‐aminophenol. Compared to the control and nonporous films, the porous films with smaller nanopores exhibit larger catalytic activity. Additionally, UV irradiation upon the nanocomposites promotes the catalytic action, due to the change in surface hydrophilicity caused by the photoisomerization of azobenzene. Recyclable use of nanocomposites demonstrates the high stability. This research provides an innovative strategy to prepare 3D curved porous films for potential on catalysis. [ABSTRACT FROM AUTHOR]

Partial shading conditions (PSC) across the solar photovoltaic (PV) array reduce the overall power yield of the PV plant. Therefore, it is essential to decrease mismatch power loss (MPL) incurred under PSC. For this purpose, total‐cross‐tied (TCT)‐based 'hybrid interconnection' schemes of solar PV array are investigated in the present research work. Proposed novel hybrid bridge‐link (BL)‐TCT and honey‐comb (HC)‐TCT interconnection schemes are found to be effective alternatives to achieve increased solar PV array output power. The performance of the proposed 'hybrid interconnection' schemes is studied by subjecting the 9 × 9 sized solar PV array under four different categories of PSC. The efficacy of the proposed 'hybrid interconnection' schemes is justified to be superior by comparing the simulation results obtained from the proposed interconnection schemes with the earlier reported conventional 'S‐P, B‐L, H‐C, and traditional TCT' interconnection schemes. Further, it is observed that output power is additionally enhanced using a bypass diode connected across individual modules of the solar PV array. The simulation results indicate that the proposed 'hybrid interconnection' schemes with values of 17.5%, 21.28%, 54.33%, and 50.4% under four categories of typical PSC have the lowest MPL relatively compared to that of literature‐reported conventional interconnection schemes. In addition, the proposed 'hybrid interconnection' schemes with the performance enhancement (PE) values of 82.5%, 78.7%, 45.66%, and 49.6% under four categories of typical PSC have the highest PE relatively compared to literature‐reported conventional interconnection schemes. Based on the comparative analysis of results obtained upon four typical PSC, it is concluded that the proposed 'hybrid interconnection' schemes provide a relatively superior output performance compared to that of the conventional 'S‐P, B‐L, H‐C, and traditional TCT' interconnection schemes. [ABSTRACT FROM AUTHOR]

Due to their promising properties such as low corrosion resistance, excellent strength, high‐temperature operation, simple formability and machining, and, most importantly, cost‐effectiveness in the industry, honeycomb‐based heterostructures have been widely used as energy storage and conversion systems for decades. Despite their low density, honeycomb structures also have strong out‐of‐plane compression and shear properties, resulting in very high unique strengths. The honeycomb‐based molded structure, which was inspired by bee honeycombs and provides a material with low density and high out‐of‐plane compression and shear properties, has found widespread use and now plays a critical role in energy conversion and storage technologies such as lithium‐ion batteries, solar cells, and supercapacitors. These materials have a lot of promise in terms of addressing and environmental concerns regarding power sources at a time when global energy demand is skyrocketing. In light of this, we contend in this research paper that complex honeycomb‐based architectures outperform conventional simple 2D designs in a wide variety of technological applications. We also go into the different synthetic methods used to make honeycomb structures and look at how these novel materials may be used for long‐term electrochemical energy transfer and storage. Finally, the current challenges and opportunities for the construction of honeycomb systems are discussed, as well as new research directions. [ABSTRACT FROM AUTHOR]

Nature evolves structures like honeycombs at optimized performance with limited material. These efficient structures can be artificially created with the collaboration of structural topology optimization and additive manufacturing. However, the extensive computation cost of topology optimization causes low mesh resolution, long solving time, and rough boundaries that fail to match the requirements for meeting the growing personal fabrication demands and printing capability. Therefore, we propose the neural synthesizing topology optimization that leverages a self‐supervised coordinate‐based network to optimize structures with significantly shorter computation time, where the network encodes the structural material layout as an implicit function of coordinates. Continuous solution space is further generated from optimization tasks under varying boundary conditions or constraints for users' instant inference of novel solutions. We demonstrate the system's efficacy for a broad usage scenario through numerical experiments and 3D printing. [ABSTRACT FROM AUTHOR]

The internal fixation of a fractured bone is generally achieved with bone screws during most orthopedic surgeries. Biodegradable screws have not received as much attention as they deserve. Biodegradable screws reduce the stress‐shielding effect, screw failure, complex, painful revision surgery for screw extraction. The vital focus of the present research is to fabricate cortical bone screws using polylactic acid (PLA) by fused deposition modeling technology. The PLA cortical screws were manufactured with different infill patterns (triangular, honeycomb, grid, and concentric), keeping other parameters constant using three‐dimensional printing. The mechanical behavior and fracture mechanism of different patterned cortical screws were observed based on compression testing and tensile testing of screws. Scanning electron microscopy (SEM) observed the surface topographical features, fracture behavior, and microstructure characterization of different patterned polymeric cortical screws were observed using SEM. Based on the SEM micrographs, mechanical characterization of compression and tensile testing shows the stress, fractures and fatigue cracks propagation at the bone screw interfaces by fractures copy. Moreover, it was observed that the fracture mechanism of ductile to brittle fracture was observed with variation in the infill pattern of the bone screw. The outcomes revealed that the cortical screw with honeycomb infill pattern has the highest compressive and tensile strength than other infill patterns. Honeycomb structured cortical screws have approximately 17% higher compressive strength and 30% higher tensile strength than the triangular patterned cortical screw due to higher bonding surface area at the intercalated layers. [ABSTRACT FROM AUTHOR]

Shape‐memory elastomer composite (SMEC) sheets, made of a honeycomb structured electrospun poly(ε‐caprolactone) (PCL) fiber mat embedded in a silicone (PDMS) elastomer, fold on themselves upon uniaxial traction. The self‐folding of the composite sheet originates from a bi‐layered structure obtained by a simple one‐step impregnation process. Indeed, the impregnation of a structured PCL fiber mat by oily PDMS in a flat Teflon mold leads, after curing, to an asymmetric composite sheet made of one PDMS flat thin layer on the mold side and one rough PDMS/PCL composite layer on the other side due to specific affinities between the three polymers involved. The self‐folded shape of such structured single sheet obtained upon uniaxial stretching and stress release is controlled by the honeycomb pattern orientation versus stretching direction, by the pattern size and by the applied uniaxial stretching stress. High shape recovery and robust shape memory cycling are also demonstrated by dynamic mechanical analysis. This innovative process based on the mat structuration allows a straightforward one‐step fabrication of shape memory sheets, with a wide scope of tunable self‐folded curvatures exhibiting efficient temperature shape recovery. [ABSTRACT FROM AUTHOR]

BACKGROUND: As one of the common VOCs, toluene is not only hazardous to human health, leading to respiratory disease, cancers, but also harmful to the environment, causing destruction of the ozone layer, photochemical smog and global warming. Catalytic oxidation is one of the most advanced technologies for eliminating VOCs and can convert VOCs to benign components such as carbon dioxide (CO2) and water. As catalysts are important in the catalytic process, finding highly active, low cost catalysts is critical. Metal phthalocyanine(MPc) has potential practical value and wide application prospects as catalysts for its uniquely high catalytic activity and selectivity. Thus, four monolithic catalysts were prepared by impregnating MPc onto cordierite honeycomb. RESULTS: Characterization by scanning electron microscopy, X‐ray diffraction, Fourier transform infrared and energy‐dispersive X‐ray spectroscopy showed that the metal phthalocyanines were successfully loaded on the cordierite honeycomb. A fixed‐bed reactor was used to examine the catalytic oxidation effects of metal phthalocyanine species, catalyst amount, feed concentration, feed flow and temperature on toluene. The result showed that the catalytic activity of phthalocyanine iron (FePc) to toluene was better than other three MPcs. The optimal reaction conditions were 120 mg catalyst, 6.3 × 10−3 mol m−3feed concentration and 250 mL min−1 feed flow. The conversion of toluene increased with increasing temperature. CONCLUSION: FePc/C also had a good catalytic oxidation effect on different aromatic hydrocarbon compounds (benzene and 1,4‐dimethyl‐benzene). The oxidation products of the catalytic system were CO2 and H2O, which met the requirements of green chemistry. FePc/C is a promising catalytic material because it has high catalytic activity and can be operated in simple conditions, such as low temperatures. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Polluted organic dyes in water are considered as some of the most serious problems affecting humans. Adsorption techniques using traditional adsorbents such as clay, zeolite, silica, active carbon, and polymers are low cost, safe, and efficient for the treatment of organic dyes in contaminated water. However, traditional adsorbents usually have low adsorption capacity (qmax). To improve qmax, graphene oxide (GO) is considered as an excellent adsorption enhancer owing to its two‐dimensional single atomic layer material of sp2‐hybridised carbon atoms arranged in a honeycomb lattice structure with high surface area, high solubility, good chemical stability, strong mechanical strength, and excellent thermal stability. In this review, the synthesis and advantage results on improving the adsorption efficiency and qmax when applying GO‐based nanocomposites as nanosorbents for organic‐dye removal are systematised and discussed in detail. [ABSTRACT FROM AUTHOR]

When being used as anodes for lithium‐ion batteries (LIBs), environmental friendly and easily available biomass‐derived carbon materials often suffer from complex preparation conditions, underdeveloped pore structures and relatively low circulation capacities. In this context, three novel biomass‐derived porous carbon materials including LRK‐6, LRK‐7 and LRK‐8 sourced from lotus roots are activated and carbonized by a simple method. The prepared material has a three‐dimensional honeycomb structure. The effects of carbonization temperature on the structure, morphology and electrochemical properties of the material are investigated in detail. Owing to its high specific surface area (831.017 m2 g−1), appropriate microporous content (0.217 cm3 g−1) and the highest mesopore capacity (0.325 cm3 g−1) together with suitable doping of N and O atoms, the as‐optimized LRK‐7 material shows a reversible specific capacity of 725.25 mAh g−1 after 100 cycles at 0.1 A g−1 and 614.60 mAh g−1 after 223 cycles at 0.3 A g−1. Besides, LRK‐7 material also exhibits high rate performance, achieving a capacity of 153.5 mAh g−1 at 9.0 A g−1. The results verify that the application of LRK‐7 as a potential anode material in the LIB will embrace a bright future. [ABSTRACT FROM AUTHOR]

Composite honeycomb sandwich structure shows the advantages of lightweight, high specific strength, and good energy absorption performance. It has been extensively applied to aviation, aerospace, rail transportation and other fields. In this study, a preparation method of multi‐layer honeycomb sandwich structure with the same bulk density is proposed. Various honeycomb sandwich structures with different layers were prepared and could effectively eliminate the effect of the change of bulk density on the mechanical properties of the experimental samples, which was proved by theory. The result of the experiment showed the variation law of transverse dimension of honeycomb sandwich structure. The results also suggest that with increasing the number of layers of the middle panel, both the compressive strength and the absorbed energy of the honeycomb sandwich structure increases. However, the transverse width of the honeycomb sandwich structure decreases under the restriction of the middle panel. When the strain was 0.409, the bearing capacity of two‐layer honeycomb and three‐layer honeycomb sandwich structure increased by 12.08% and 24.16%, respectively, the absorbed energy increased by 10.21% and 21.85%, respectively, and the transverse width decreased by 2.94% and 3.50%, respectively. [ABSTRACT FROM AUTHOR]

A novel method to find bound states in general tight‐binding Hamiltonians with semi‐infinite leads is reported. The method is based on the recursive S‐matrix method, which allows to compute iteratively the S‐matrix of a general system in terms of the S‐matrices of its subsystems. The condition that the S‐matrices of the subsystems must accomplish to have a bound state at energy E is established. Energies that accomplish this relation, can be determined with high accuracy and efficiency by using the Taylor series of the S‐matrices. The method allows to find bound states energies and wavefunctions in (BIC) and out (BOC) of the continuum, including degenerate ones. Bound states in nanoribbons with wider sections are computed for square and honeycomb lattices. Using this method, the bound states in a graphene nanoribbon with two quantum‐dot‐like structures which are reported to have BICs by using another technique are verified. However, this new analysis reveals that such BICs are double, one with even and the other with odd wavefunction, with slightly separated energies. In this way, the new method can be used to efficiently find new BICs and to improve precision in previously reported ones. [ABSTRACT FROM AUTHOR]

Molecular adsorption on noble‐metal surfaces influences the Rashba effect in the Shockley surface state (SS), but the underlying mechanism remains unclear. Melamine is a simple molecule with a symmetric backbone consisting of a heterocyclic ring. It self‐assembles into a rosette‐like superstructures on Au(111) via double intermolecular hydrogen bonds. In this study, the growth process and structure of this hydrogen‐bonded organic framework (HOF) using low‐energy electron diffraction and X‐ray photoemission spectroscopy is revealed. Above room temperature, it is impossible for melamine to be adsorbed on Au(111) as a monomer, but it is adsorbed collectively as a hydrogen‐bonding network. The melamine HOF has a characteristic hexagonal honeycomb structure (MHC), which significantly affects both the structure and electronic states of Au(111). A theoretical approach reveals that MHC induces a hexagonal periodic deformation in the structure of Au(111) and introduces a new periodic potential in the surface electronic system. Angle‐resolved photoemission spectroscopy measurements of MHC/Au(111) indicate that the bulk sp band is strongly folded back, enhancing the Rashba splitting of the SS of Au(111). Furthermore, spin‐ and angle‐resolved photoemission spectroscopy reveals that the enhanced Rashba splitting of the SS by the MHC is the largest reported to date for the adsorption system on Au(111). [ABSTRACT FROM AUTHOR]

Mechanical metamaterials recruit unique mechanical behavior that is unavailable in bulk materials from a periodic unit cell structure with a specific geometry. However, such metamaterials can typically not be reconfigured once manufactured. Herein, the authors introduce shape morphing of a hydrogel metamaterial via spatio‐selective integration of responsive actuating elements to reconfigure the mesoscale unit cell geometry to reach programmable auxeticity on the macroscale. Via thermal control, the unit cell angle of a honeycomb structure can be precisely programmed from 68° to 107°. This results in negative, zero, or positive Poisson's ratio under applied tensile strain. The geometrical reconfiguration with resulting programmable auxeticity is predicted and verified by finite element (FE) simulation. This concept of shape‐morphing hydrogel metamaterials via the addition of actuating struts into otherwise passive architectures offers a new strategy for reconfigurable metamaterials and extends applications of hydrogels in general. It can be readily extended to other architectures and may find applications in mechanical computing as well as soft robotics. [ABSTRACT FROM AUTHOR]

Tin and mixed tin/germanium thin films hold great potential for a variety of different applications such as anodes for lithium ion batteries or optical components in new LED developments. While the physical and chemical properties of these materials are promising, the fabrication of nanostructures with tunable composition and electronic properties is eminently important to overcome several problems in application. In this work we report on the preparation and characterization of inverse opal‐structured Sn and Sn/Ge thin films with a pore size of 200 nm on a wide variety of substrates obtained by a simple, up‐scalable wet‐chemical synthetic route involving soluble [Sn9]4−, [Ge9]4− and mixed Sn/Ge Zintl clusters. The resulting honeycomb structures are characterized by SEM, EDX, XPS, and Raman spectroscopy. Their porous structure and tuneable composition makes them attractive candidates for electrochemical applications such as anode materials. [ABSTRACT FROM AUTHOR]

Summary: The effects of high‐temperature cooking (HTC), high‐pressure homogenisation (HPH), ultrasonic treatment (UT), and their combination (i.e., UT–HTC, HPH–HTC, and UT–HPH) on the physicochemical, structural, and in vitro hypoglycemic properties of bamboo shoot dietary fibres (BSDF) were investigated and compared. The soluble dietary fibre, arabinose, and glucose contents increased in all modified samples. The BSDF obtained by UT had a loose structure with a honeycomb appearance on the surface. UT–HTC resulted in the highest water‐holding capacity (8.38 g g−1) and α‐amylase activity inhibition ratio (56.14%). The BSDF modified by HPH–HTC had the lowest relative crystallinity (27.96%). Compared with those of control check (CK), the oil‐holding and swelling capacities of samples treated by UT–HPH increased by 55.35% and 91.47%, respectively. The glucose adsorption capacity of samples followed the order: UT–HTC > UT–HPH > HPH–HTC > HPH > UT ≈ HTC. Furthermore, the maximum glucose dialysis retardation index values of BSDF treated by UT–HPH, HPH, and HPH–HTC increased by 44.51%, 30.61%, and 27.20%, respectively, in comparison with CK. This study indicated that UT–HTC, HPH–HTC, and UT–HPH are innovative and promising modification methods to obtain BSDF with excellent physicochemical and functional properties. [ABSTRACT FROM AUTHOR]

The low‐velocity impacts that represent the equipment drop during maintenance and production, crash and drops of luggage that may occur during transportation and bird strikes during takeoff may occur in aircraft parts where honeycomb composite structures are used. Therefore, the low‐velocity impact (LVI) resistance of aircraft components is crucial. In this study, the effect of graphene nano platelets (GNPs) on the LVI behaviors of the BFR (basalt fiber reinforcement) laminated face‐sheets and the interface adhesive between the face‐sheet and the aluminum honeycomb core for composite sandwich structures were investigated. LVI tests were applied to GNPs doped and un‐doped BFR/aluminum composite sandwich samples to determine the values of the impact forces, displacements, interaction times, and absorbed energy at two different energy levels of 10 J and 20 J. The surface damages in the impact zones of the GNPs doped and un‐doped BFR laminated top face‐sheets of the sandwich samples were investigated on a macro scale with liquid penetrant. The damage formation and development of GNPs were detected in the cross‐sectional micro‐images of the top face‐sheets. SEM analysis was accomplished to define the fracture mechanisms provided by GNPs. As a consequence of tests and damage analysis, it was reported that GNPs increase the impact resistance of BFR/aluminum honeycomb composite sandwiches and limit and reduce damage development. GNPs showed increases in force and rebound energies of approximately 16.1% and 21.1% for 10 J, and approximately 8.2% and 14.7% for 20 J, respectively. [ABSTRACT FROM AUTHOR]

The bonding of a honeycomb core to the thermoset prepreg facesheets by co‐curing them allows one to manufacture composite sandwich structures in a single operation. However, the process is strongly dependent on the prescribed autoclave cure cycle. A previously developed physics‐based simulation can predict the bond quality as a function of the process parameters. The disadvantage of physics‐based simulations is the high computational effort needed to identify the optimal cure cycle to fabricate sandwich structures with desired bond‐line properties. Theory guided machine learning (TGML) methods have demonstrated their capabilities to reduce the computational effort for different applications. In this work, three TGML models are trained on a data set produced from physics‐based simulations to predict the co‐cure process of honeycomb sandwich structures. The accuracy of the TGML models were compared to select the best performing predictive tool. In addition to reduction of computational time by orders of magnitude, we demonstrate how the TGML tools can also quantify the contribution of each process parameter on the properties of the fabricated part. The most accurate model was implemented in an optimization routine to tune the input process parameters to obtain the desired properties such as the bond‐line porosity and facesheet consolidation level. This methodology could be extended to any process simulation of composites manufacturing processes. [ABSTRACT FROM AUTHOR]

In this study, a three‐dimensional bandpass frequency selective surface (FSS) with a new fabrication technology is proposed and designed based on slotlines. The proposed FSS consists of silver paste circuits printed on aramid paper, and is vertically and horizontally arranged to form a periodic array in honeycomb structure. To better understand the design principle of the proposed FSS, the equivalent circuit model (ECM), single‐polarized structure, and dual‐polarized structure are presented and analyzed, respectively. The proposed FSS exhibits a passband at 4.1 GHz with a fractional bandwidth of 71.5% at x‐polarization and 66.2% at y‐polarization with reflectivity less than −10 dB. Moreover, the reflection and transmission coefficients have relative stable properties up to 30° for the oblique incidence. Then, the proposed structure is fabricated and measured to verify the design strategies. The measured and simulated results have reasonable agreement under a large variation of incident angles. [ABSTRACT FROM AUTHOR]

The widespread utilization of cellulose nanofibril (CNF) has been significantly hindered by its inherent flammability. To explore the potential of using CNF aerogel as sustainable material with good fire‐retardant and thermal‐insulating properties, CNF aerogel is modified by in situ supramolecular assembly of melamine (MEL) and phytic acid (PA). This strategy addresses CNF's flammability and avoids the environment issues associated with the incorporation of traditional fire‐retardant. The modified aerogel exhibits highly porous honeycomb structure with low density and good mechanical properties. After modification with MEL–PA, the aerogel exhibits highly improved shape integrity during burning, higher thermal stability, and favorable combustion behavior for fire retardancy. The heat transfer of the modified aerogel is well hindered, which demonstrated effective thermal insulation performance. In view of the excellent thermal and fire‐retardant properties, the MEL–PA/CNF composite aerogel can be a potential fire‐retardant and thermal‐insulating material for applications such as clothing, building, and electronic devices. [ABSTRACT FROM AUTHOR]

The bimetallic oxides of general M4M'2O9 formula, where M=Fe, Co, Mn and M'=Nb or Ta, form a family of linear magnetoelectric materials, for which properties depend on the nature of the M,M' pair. In the present study, the structural, magnetic and magnetoelectric properties of a new member, Co2Fe2Ta2O9, synthesized in polycrystalline form, are reported. This compound crystallizing in the P‐3c1 trigonal '429' structure (a=5.2009 (1) Å, c=14.1986(1) Å and V=332.613(2) Å3) is found to be antiferromagnetic below TN=53 K. Although the structural features are intermediate between the Co4Ta2O9 and Fe4Ta2O9 limit members, a very different magnetoelectric behaviour is observed. In order to reveal the differences between M4M'2O9 with M=Fe or Co or mixed and M'=Ta or Nb, a comparison between these six compounds is proposed. [ABSTRACT FROM AUTHOR]

In this paper, the first‐principles calculations based on the Density Functional Theory (DFT) have been used to study the effect of strain on the structural, electronic, optical and thermoelectric properties of the puckered Si2SeS monolayer. Our calculations show that the puckered Si2SeS monolayer has an indirect band gap of 1.30 eV at the equilibrium state, which can be tuned by biaxial strain and the semiconductor–metal phase transition occurs at −10%. Interestingly, a high absorption coefficient exceeds 107 cm−1 in the visible light region under compression biaxial strain was predicted. The electronic Figure of merit (ZTe) of puckered Si2SeS monolayer reaches 2.55 under the tensile biaxial strain of +6%. The presented results show the promising potential of puckered Si2SeS monolayer for optoelectronic and energy conversion applications. [ABSTRACT FROM AUTHOR]