Search

Vitrified-bond diamond composites are materials commonly used for grinding wheels in the grinding process of silicon wafer production. In this study, the mechanism of the in situ honeycomb structure formation in the sintering process of composite materials was explored by changing the binder content without adding a pore-forming agent.The results show when the content of vitrified bond is 55 wt%, the in situ honeycomb structure forms, resulting in a porosity of 60.68 % and bending strength of 23.03 MPa.The X-ray diffraction (XRD), Raman spectroscopy (RS), and thermogravimetry-differential thermal analysis (TG-DTA) results show that no graphitization of diamond grain occurs during sintering. The bonding ability between the vitrified bond and diamond grain, along with the microstructure of vitrified-bond diamond composites, was studied using scanning electron microscopy (SEM). Moreover, the results of energy spectrum analysis (EDS) show that the diffusion and segregation of Na at the interface between the diamond particles and the vitrified bond improve the bonding strength, and the vitrified bond can effectively bond with the diamond particles. Finally, the formation mechanism of the honeycomb structure was elucidated using the surface and interface sintering theory. [ABSTRACT FROM AUTHOR]

In this research work, laser powder bed fusion (LPBF) based stainless steel 316L (SS316L) was fabricated and its corrosion behaviour was analysed for the oil-gas piping application. The Field Emission Scanning Electron Microscopy (FESEM) analysis of the LPBF SS316L specimen revealed the presence of 1–2 μ m size honeycomb structure and 2–10 μ m size tabular structures. Nano-size particles in the range of 100 nm–500 nm were formed between the two tabular cells as well as their boundary regions in the LPBF SS316L specimen. The energy-dispersive X-ray spectroscopy (EDS) analysis of the nanoparticle confirmed the presence of Si with a percentage of 1.4% along with 15.9% of Cr and 1.6% of Mo that have the characteristic of dispersion strengthening of the LPBF SS316L specimen. In addition, the δ-ferrite phase was observed in tabular structure boundaries and intercellular regions of solute in the LPBF SS316L specimen. Moreover, among the three crystallographic orientations {001}{101}and {111}, no domination behaviour was observed from the Electron Backscatter Diffraction (EBSD) study. The Transmission Electron Microscopy (TEM) analysis confirmed the presence of nano twin structures that had a span of several nm on the FCC austenite unit cell. These twins came under the {111} category twining that often occurred in FCC metals. A potentiodynamic polarization test was conducted on the LPBF SS316L specimen at five different time periods (i.e., 0, 7, 15, 34 and 56 h) and it was assessed that the 0 and 15 h immersion specimens exhibited superior corrosion resistance compared with other LPBF SS316L specimens. The Nyquist plot revealed that the 0 and 15 h immersion specimens offered the highest resistance value of 1846.1Ω and 1720.3 Ω, respectively against corrosion. The Bode plots of the LPBF SS316L specimen followed a similar trend as the Nyquist plots. [ABSTRACT FROM AUTHOR]

The effect of a nano-honeycomb cathode on the performance of a microtubular solid oxide fuel cell is investigated. We successfully prepared nano-honeycomb cathodes with high unsealing pore porosity (∼64.6%) and high structural strength by freeze casting, which improved the adsorption and dissociation of oxygen. We added gadolinium doped ceria (GDC) nanopowder to the lanthanum strontium cobalt ferrite (LSCF) cathode material. The cell performance of the nano-cell structure of the GDC-LSCF cathode is significantly improved compared to a traditional GDC-LSCF cathode with a spongy porous structure. At 750 °C, the current density is 1450 mA cm−2 and the power density is 475 mW cm−2, which is better than that of conventional cathode structures. We discussed the effects of the honeycomb structure on the cell, including the migration of silver paste as a cathodic collector to the GDC-LSCF interface and the improvement of the activity of the oxygen electrodes. • The fabricated nano-honeycomb cathode had a large surface area and large pore channels. • I–V–P curves indicated the success of the HC-MTSOFC compared to TC-MTSOFCs. • Scanning electron microscopy determined the silver diffusion after 10 h of operation. [ABSTRACT FROM AUTHOR]

• Honeycomb-structured S and N dual-doped graphene-like carbon (SNG) is prepared by low-temperature (850 °C) pyrolysis of S-doped carbon nitride with Mg. • Mg acts as a reducing agent for graphitizing the carbon precursor and as a precursor for new Mg 3 N 2 and MgS products, which play as pore-generating templates for honeycomb-like structure. • Rh/SNG catalyst outperforms state-of-the-art commercial Pt/C for hydrogen evolution reaction (HER) with an extremely lower overpotential of 13 mV at 10 mA cm−2 and outstanding stability. • High crystallinity, superior electrical conductivity, and hierarchically porous honeycomb structure of SNG doped with N and S are credited with this remarkable HER performance. State-of-the-art electrocatalysts are based on catalytically active metal deposited on conductive porous carbon. Herein, we report a new strategy of engineering of a honeycomb-structured S and N dual-doped graphene-like carbon (SNG) as a supporting material for Rh catalysts by a simple low-temperature (850 °C) pyrolysis of S-doped carbon nitride (S-CN) in the presence of Mg. Interestingly, here Mg plays a marvelous dual role not only as a reducing agent for graphitizing the S-CN but also as a precursor for new Mg 3 N 2 and MgS products, which play as pore-generating templates for honeycomb-like structures. This features highly robust graphitized carbon with excellent electrical conductivity, proper S and N content, and porosity, making it highly desirable as catalyst support. Supporting Rh (5.2 wt.%) on SNG outperforms state-of-the-art commercial Pt/C electrodes for hydrogen evolution reaction (HER) under alkaline settings (1.0 M KOH) with an extremely lower overpotential of 13 mV at 10 mA cm−2, a lower Tafel value, and a higher turnover frequency. In addition, Rh/SNG as the cathode for industrial water electrolysis in 6.0 M KOH electrolyte at 70 °C shows excellent performance with only 1.76 V cell to achieve 500 mA cm−2 and maintains long-term durability with negligible decay. The distinctive properties of SNG, including S and N dual doping, high graphiticity, superior electrical conductivity, and honeycomb-like hierarchical meso‑ and macropore structure, are credited with this remarkable HER performance. The S and N dopants in the SNG framework optimize the electronic structure of the Rh by synergistic interaction between them as illustrated by first-principal density functional theory calculations and electronic structure analysis. [Display omitted] [ABSTRACT FROM AUTHOR]

• Ni 6 W 6 C/Co 2 O 3 @C composites are prepared from glucose, an eco-friendly material. • EAB can reach 7.12 GHz at the thickness of 2.04 mm and RL min is −56.68 dB at 5.43 GHz. • We designed absorber and the results showed that the microwave absorber can achieve an average EMW loss of more than 99 % in the 0.3–16.04 GHz frequency band and an average EMW loss in the 16.04–18 GHz frequency band is more than 90 %. In recent years, the synthesis of absorbing materials using green and environmentally friendly natural raw materials have become a research topic, but green and environmentally friendly materials with both high performance and simple synthesis steps still need to be developed. In this work, glucose and metal organic framework (MOF) were used to prepare composite materials with strong absorbing ability and low cost. We chose glucose, which is convenient to purchase on the market, as the raw material and constructed MOF derivatives with carbon shell skeleton nanostructures through a simple method of hydrothermal and annealing. Compared to the raw materials of traditional absorbing materials, glucose has environmentally friendly, low-cost and green characteristics. We characterized the microstructure and morphology of the material. In addition, we also analyzed the material composition and absorption mechanism of Ni 6 W 6 C/Co 2 O 3 @C. We have found from the theoretical analysis and simulation results of transmission lines that the minimum reflection loss (RL min) value of Ni 6 W 6 C/Co 2 O 3 @C material at 5.43 GHz and 4.76 mm is −56.68 dB. And the effective absorption bandwidth (EAB) at 2.04 mm can reach 7.12 GHz. We load the best sample to the honeycomb structure, a broadband microwave absorber was designed for simulation. The results show that the broadband microwave absorber can achieve an average electromagnetic wave (EMW) loss of more than 99 % in the 0.3–16.04 GHz frequency band (RL value is less than −20 dB), and an average EMW loss of more than 90 % in the 16.04–18 GHz frequency band (RL value less than −10 dB). The composite structure of glucose and MOF derivatives enhances the dielectric loss of the material and enriches various EMW loss mechanisms. Finally, a green, environmental-friendly, high-performance absorbing material with a simple synthesis method is prepared. These results provide insights into the research on EMW absorption of composite materials and new methods for referring. [ABSTRACT FROM AUTHOR]

• The models for thermal conductivity tensor of two types honeycombs are proposed. • Impact of the wall uniformity within honeycomb on the thermal property is quantified. • Honeycomb ETC's max anisotropic porosity reduces as thermal conductivity ratio rises. The effective thermal conductivity (ETC) is a critical parameter for simulating macroscopic heat transfer processes in composite materials, which estimation is particularly critical where the thermal conductivity of the composite phases is completely different. The huge difference in thermal conductivity of the composite phases makes their volume fraction modulation a classical way to reach the desired thermal conductivity. Nevertheless, the typical manufacturing process of honeycomb cellular structures allows various degrees of stretching of the structure, leading to various honeycomb geometries. In these 'real' structures some of the honeycomb wall sides are twice as thick as other parts, modifying the symmetry of the system with respect to honeycomb with uniform wall side thickness. A noticeable example of these composites is that of a hexagonal metallic honeycomb structure filled with phase change material (PCM) which is a widely utilized material in the field of thermal storage and thermal management by exploiting the heat absorbed/released by the PCM phase during its melting/solidification. While the thermal response of a PCM composite during a thermal cycle is not only defined by thermal conductivity (but also by cell size), this represents the basis for the with the optimization of a system based on a composite PCM. For this reason, in this study, steady-state simulations of heat transfer in unit honeycomb cells in different directions perpendicular to the cell axis are conducted to quantify the impact of morphology on the thermal property of the different wall types within honeycomb structures. The results demonstrate that in both SHS and DHS, the porosity exhibiting maximum anisotropy of ETC decreases as the thermal conductivity ratio increases. Moreover, simple predictive models for calculating the ETC in all directions are proposed for each type of honeycomb, considering a wide range of porosity and thermal conductivity ratio, with a relative error limited to 2 %. [Display omitted] [ABSTRACT FROM AUTHOR]

High temperatures can significantly diminish the efficiency of solar photovoltaic panels, emphasizing the critical need for effective thermal management strategies. While the use of phase change material has shown promise in this regard, issues arise from non-uniform temperature distribution within the phase change material, limiting its overall effectiveness. This paper introduces an innovative solution by incorporating a novel honeycomb-like aluminum structure into the phase change material tank, aiming to address these challenges. Numerical investigations explore various configurations involving different phase change material volumes and aluminum honeycomb grid thicknesses. The honeycomb structure proves effective in preventing the formation of a single high-temperature melting pool, ensuring a more uniform distribution of melting zones throughout the phase change material. Compared to scenarios without the honeycomb structure, the proposed design achieves an additional 10 °C reduction in photovoltaic cell temperature, translating to a noteworthy 0.57% improvement in panel efficiency. This enhancement is particularly significant given the baseline low efficiency of the photovoltaic panel, which stands at 14.7%. Furthermore, the study reveals that increasing the thickness of the aluminum grid contributes to enhanced temperature uniformity, reducing the maximum temperature by up to 4 °C. The findings underscore the potential of the proposed honeycomb structure. • A novel aluminum honeycomb structure is proposed for photovoltaic panel thermal management. • Compared to panels cooled without the honeycomb, it achieves a 10 °C temperature reduction. • The structure enhances photovoltaic panel efficiency by 0.57%. • Uniform temperature distribution and melting zones are achieved in the phase change material zone. • Improved thermal management enhances efficiency, prolongs panel lifespan, and ensures system reliability. [ABSTRACT FROM AUTHOR]

Flexible piezoelectric sensors have received widespread attention in wearable electronics for their ability to convert mechanical energy into electrical energy, while the insufficient output power and complex preparation process have limited their application. In this work, several honeycomb structures based on graphene macro-film (GAMF) were created via laser engraving, which can utilize negative Poisson's ratio (NPR) properties to improve the output electric performance of flexible piezoelectric sensors. The effect of different electrode materials on the piezoelectric output was investigated in the experiments and compared with the theoretical equations, indicating that the output power of the sensor could be enhanced up to 142 % by improving the materials auxetic mechanical properties. The stability tests have proven that the sensors can operate effectively for a long time under different operating conditions. Moreover, the optimized sensor shows powerful potential for monitoring human movements such as finger tapping, joint bending, and foot stepping. This work opens up a new development path for the preparation of convenient and high-performance wearable electronic devices. The negative Poisson's ratio characteristic of the honeycomb graphene macro-film is used to increase the deformation of PVDF film to increase the electrical output performance of the flexible piezoelectric sensor. The optimized sensor can be used to detect human movements. [Display omitted] • Honeycomb graphene macro-films with different mechanical properties were prepared by laser engraving. • Flexible piezoelectric sensors based on honeycomb graphene macro-films are prepared. • The output performance of piezoelectric sensors can be improved by adjusting mechanical properties of electrode materials. • The flexible piezoelectric sensors can be used to detect human movements. [ABSTRACT FROM AUTHOR]

• Three kinds of honeycomb structures were printed using carbon fiber reinforced composites, and the tensile mechanical properties of honeycomb structures were studied by combining experimental and simulation analysis methods. Finally, the relationship between fracture toughness and fractal dimension of tensile fracture surface is analyzed by fractal theory. The study employed chopped fiber-reinforced nylon composite, referred to as "Onyx," along with continuous carbon fiber materials. Using the material extrusion manufacturing process, three sandwich structures were created: a conventional, a concave hexagonal with negative Poisson's ratio, and a feather-inspired structure. Tensile testing and finite element simulations were conducted to analyze their tensile properties and crack propagation paths under tension. Fractal dimensions were calculated for each structure: the standard structure had a dimension of 1.4626, the bionic feather-inspired was 1.4810, and the negative Poisson's ratio concave hexagonal structure measured 1.4973. [ABSTRACT FROM AUTHOR]

• A class of modified hexagonal honeycomb to realize pattern transformation. • Honeycomb's elastic constants are derived by theoretical energy analysis. • Honeycomb structures exhibit auxetic behavior after pattern transformation. • The cell/node of the honeycomb has a rotating behavior after pattern transformation. • The underlying mechanism of pattern transformation is revealed for honeycomb. Pattern transformation, as one of the special properties of mechanical metamaterials, is widely found in elastic porous structures and gradually expanding to honeycomb structures. Inspired by the higher-order flower-like buckling pattern of hexagonal honeycomb, and generalizing the geometry of structures that pattern transformation occurs under uniaxial compression, this paper proposes a Modified Hexagonal Honeycomb(MHH) structure by adjusting the thickness ratio α and the deflection extension angle θ of the cell wall to topologically reconstruct the honeycomb structure to initiate the first-order quasi-flower-like buckling pattern under uniaxial loading. Results show that the quasi-flower-like pattern transformation appears directly for the MHH structure under uniaxial compression, accompanied with a transition of the Poisson's ratio, from positive to negative. And the butterfly pattern, which appears for traditional hexagonal honeycomb only under biaxial loading, is also observed for the MHH under uniaxial compression. The relative size of the nodes among cell walls is believed to play a crucial role on the appearance of the pattern transformation of the honeycomb structure. This work has revealed the underlying physical mechanism for pattern transformation of honeycomb structures, and would also extend the application range of honeycomb structures to the design of elastic dampers, bending/torsion actuators, or robot drive joints. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis and characterization of modified NH 2 -MCM-41 for drug release. • Performance of modified NH 2 -MCM-41 nanoparticles improved compared to MCM-41. • Analysis of Adriamycin, Metformin and Naproxen drugs release. The aim of this work is the preparation and characterization of modified mesoporous silica NH 2 -MCM-41 (NM-41) nanoparticles (NPs) in comparison to MCM-41 (M−41) with the aim of obtaining a pH-sensitive system for controlled drug release (CDR) applicable in cancer treatment. Three drugs were used for CDR studies including Adriamycin, Metformin and Naproxen, and loaded onto the mesoporous silica. The samples were prepared and analyzed by solid characterization methods including FTIR, XRD, SEM, TEM, BET, and DSC analyses. The SEM images clearly showed the increase in surface porosity of NM-41 nanocarriers (NCs) compared to M−41 NCs. The CDR behavior of the obtained NCs was investigated at pH 1.5–3.5 (simulated gastric fluid media-SGF), pH 6 (simulated intestine fluid media-SIF) and pH 7.35–7.45 (simulated body fluid media-SBF). The results showed that the performance of modified NM-41 NPs improved compared to M−41, and the performance of modified NM-41 NPs at SIF and SBF pHs is much higher than SGF, which shows the success in the preparation of drug pH-sensitive NCs for CDR. The results of drug loading showed that the amount of Adriamycin, Metformin and Naproxen drugs in modified NM-41 NPs is significantly higher than M−41. Furthermore, survival studies were conducted for the prepared systems and the results showed good biocompatibility of the prepared drug delivery systems (DDS). [ABSTRACT FROM AUTHOR]

• SiCN honeycomb ceramic is prepared from 3D printed photocurable polysilazane. • The optimal composition of acrylate and polysilazane affords high-strength ceramic. • Combination of acrylate and polysilazane results in high-content free carbon. • SiCN honeycomb ceramic has excellent intrinsic microwave-absorbing property. The combination of 3D printing technology and polymer-derived ceramic route provides an attractive strategy to construct microwave-absorbing honeycomb with fine structure through flexible process. However, preparation of honeycomb ceramics with both excellent mechanical and microwave-absorbing properties is still challenging. Herein, SiCN honeycomb ceramic was fabricated by stereolithography from UV curable polymeric precursor consisting of polysilazane and multifunctional acrylates. By optimizing the multifunctional acrylates and its ratio, the decomposition of organic moiety and the ceramization process of precursor are matched, rendering the achieved ceramic with high compactness. The hardness and specific compressive strength of SiCN honeycomb ceramic reach as high as 14.3 GPa and 333.3 MPa/(g·cm3), respectively. Meanwhile, at low pyrolysis temperature, the copolymerized acrylate and polysilazane that formed during curing process was converted to free-carbon nanodamins in-situ, which endows SiCN honeycomb ceramic with the minimum reflection loss of –49.0 dB, namely microwave absorption rate over 99.99%. [ABSTRACT FROM AUTHOR]

Space is one of the most avant-garde sectors for additive manufacturing as the inherent characteristics of this technology allow the creation of complex and lightweight 3D structures. Using this brand-new design tool, it was possible to design the pumping system holder of the MicroMED instrument, a particle analyser developed for ExoMars 2022 mission. The geometry of the holder was optimized using a finite element approach. The effectiveness of the proposed solution was evaluated by comparing the performance of two different designs using the AlSi9Cu3 alloy. One solution was based on micro-milling and the other on Selective Laser Melting. In order to validate the designed SLMed holder, a mockup was produced and successfully tested in the mission's mechanical environment. • Structural support based on honeycomb structure has been designed for AM and a mock-up has been realized in AlSi9Cu3. • AM designed structural support provides mass saving and improved dynamic performance compared to micro-milled design. • The breadboard has been tested in a representative mechanical environment for ExoMars 2020 mission. [ABSTRACT FROM AUTHOR]

The battery-pack system of electric vehicles is prone to collide with low obstacles on the road, causing battery short circuits and even explosions. It poses a great safety threat to passengers and drivers. The honeycomb structure's high energy absorption and lightweight properties have made it a popular choice in the automotive industry. This paper designs different bio-inspired honeycomb structures to a battery-pack system of electric vehicles to improve the crashworthiness performance. The effects of different bio-inspired honeycomb structures on the crashworthiness of a battery-pack system during frontal impact are analyzed based on a nonlinear finite element model. First, the geometric parameters of seven different bio-inspired honeycomb individual units are described. The overall structure of the honeycomb is applied to a battery-pack system. Second, the nonlinear finite element model of a battery-pack system and honeycomb structures are established and verified. Then, collision simulations are conducted. The deformation and the maximum stress of a battery-pack's bottom shell are computed. The energy absorbed by the honeycomb structures during frontal impact are investigated. The results indicate that the proposed bio-inspired honeycomb structure mimicking grass stems improves the safety performance of battery-pack systems most. Finally, a parametric design is carried out on the bio-inspired honeycomb structure. The effects of wall thicknesses and the number of replacement hexagons on the crashworthiness performance are analyzed. The honeycomb structure preforms best when thickness is 1 mm and the number of replacement hexagons is 2 and 4. The optimized bio-inspired honeycomb structure reduces the deformation of the battery-pack' bottom shell by up to 30%, and maximum stress by 10%. • The deformation, maximum stress, and energy absorption are investigated. • The effects of seven bio-inspired honeycomb structures are analyzed. • Parametric design is carried out to further improve the crashworthiness performance. • The deformation of the bottom shell can be reduced by up to 30%. [ABSTRACT FROM AUTHOR]

• A honeycomb-structured superhydrophobic coating is prepared. • The coating exhibited a high visible light transmittance (90.0%). • By regulating structure, the haze of the coating can be adjusted (8.9%-54.1%). • The coating has excellent mechanical abrasion and weathering resistance. Transparent superhydrophobic coatings have excellent self-cleaning performance and are particularly suitable for applications in the fields of outdoor photovoltaic displays, solar power generation, and windows. However, the micro-nanostructures required for superhydrophobic coatings make them poor abrasion-resistant and foggy, and hence transparent superhydrophobic coatings with good practicality still remain great challenging. Here, we report honeycomb-structured coatings simultaneously with high transparency, abrasion-resistance and superhydrophobicity by fabrication of honeycomb epoxy resin structure via PDMS template method and subsequent spraying of hydrophobic SiO 2 nanoparticles. The coatings with different honeycomb structures exhibit average transmittance of 90.0 %, and the haze in the range of 8.9–54.1 %. Both the honeycomb structure formed by hard epoxy resin and strong adhesion of hydrophobic SiO 2 nanoparticles enable the coatings to maintain superhydrophobicity after harsh mechanical abrasion and weathering. [ABSTRACT FROM AUTHOR]

The natural beesʼ honeycombs maintain long-term structural stability in harsh environments, employing a highly material-efficient approach. However, the reasons remain somewhat ambiguous. To clarify the stabilization mechanism and investigate quasi-static compression responses of double-layer ordered cellular structures, honeycomb, Tóth and single-layer cellular structures with a relative density (ρ r) of 25.84 % were fabricated using 3D printing technology. Then, quasi-static compression experiments in three directions were conducted. Further, a numerical study was conducted to uncover the stabilization mechanism and effect of ρ r on compressive behaviors. Results revealed that the stabilization mechanism was mainly attributed to bearing load priority of intermediate layer and its inhibition on formation of plastic hinges. A relative density of 5.17 % served as a transition point for deformation mode, beyond which honeycomb and Tóth structures exhibited stronger in-plane compressive strength at expense of less sacrificed out-of-plane compressive strength, below which they both exhibited more stable compressive curves compared to single-layer cellular structures, which were favorable for energy absorption. This study clarifies the stability mechanism of beesʼ honeycombs and addresses the lack on compression behaviors of double-layer ordered cellular structures. Moreover, it introduces two available bionic structures with controllable deformation modes to expand the application of single-layer cellular structures. [ABSTRACT FROM AUTHOR]

Hydrogen production from biomass is an efficient and clean utilization way for renewable energy to significantly alleviate the energy crisis. In order to improve the biomass conversion efficiency, a device combining honeycomb structure wood and inert porous pellets was proposed, and the combustion characteristics of honeycomb wood was studied with different biomass species and pore structures. The results indicated that softwood had the higher syngas yield compared with hardwood, and the hydrogen yield was up to 9.0 %. The increasing of inlet air velocity improved combustion temperature, but it was not conducive to syngas production. In addition, circle shape structure showed the stable combustion rate and the high conversion efficiency due to the uniform pore distribution. With the increasing of pore number, outlet temperature and hydrogen production increased first and then decreased. Moreover, syngas yield improved as the pore diameter increased and the maximum hydrogen growth rate reached 256 %. Meanwhile, the co-combustion mechanism of honeycomb wood and inert pellets was revealed, and the efficient realization of heat-hydrogen coproduction had practical guiding significance for optimizing the energy structure. [ABSTRACT FROM AUTHOR]

• Combining ML and FE methods to accelerate the design process of honeycomb structures. • Using 2D unit cell surrogate 3D honeycomb structures. • CDAE with a pixelation strategy is proposed to manage FE data. • LSTM uses latent features and external loads to predict structural dynamic responses. In this study, a novel framework was presented for accelerating the prediction of the mechanical response of honeycomb structures under dynamic crushing, using 2D cells to surrogate 3D honeycomb structures by machine learning (ML). The sizes of different honeycomb structures were designed and the necessary training data obtained through finite element (FE) simulations, but without using any explicit design parameters of the honeycomb cells in the ML model. A pixelization method of FE model was proposed to separate the complete cell structure from the honeycomb FE grid data and convert it into a matching pixel map. FE data was structuralized while reducing the large amount of computational power consumed in identifying complex array structures. Unsupervised automatic extraction of low-dimensional features of pixel maps was performed using a convolutional denoising autoencoder (CDAE). The crushing velocity and the extracted latent features were used as the input of the long-short term memory (LSTM) network to predict the crushing deformation and stress-strain curve of the honeycomb structure under different dynamic loading. Results showed that the constructed ML model could describe the dynamic crushing response behavior. Compared with the traditional FE method, the prediction model was 4.45 × 103 and 1.05 × 103 times faster in predicting the stress-strain and structural deformation response, respectively. The mechanical response prediction model provided a method for rapidly evaluating the dynamic mechanical response behavior of similar periodic array structures using FE model data, which could be beneficial for the design and development of equipment based on bionic structures. [ABSTRACT FROM AUTHOR]

Highly porous aluminum alloys and honeycomb structures may be utilized as single-use shock absorbers in landing gear and other elements of spacecraft thus ensuring safety of the landing process. This paper presents the results of studies that make it possible to estimate mechanical properties and shock-absorbing characteristics of highly porous aluminum alloys and honeycomb aluminum alloy structures, the initial average densities of said alloys and structures ranging from 330 to 2250 kg/m³. We list analogs that correspond with different stages found on stress-strain curves of highly porous aluminum alloys and honeycomb structures. The paper also provides the foundations of calculating the specific and effective energies of shock absorption. • The deformation diagrams of cellular aluminum are close to the idealized one. • Specific and effective impact absorption energy calculated by the deformation diagram. • Some honeycomb structures have a deformation diagram with hardening. • The presence of hardening worsens the shock-absorbing characteristics. • The deformation diagram depends on the porosity, matrix material and pore structure. [ABSTRACT FROM AUTHOR]

Aluminum honeycomb has been used widely on the spacecraft, as it has high strength mass ratio and good designability. In order to reduce the channel effect of honeycomb core, the multiple "Y" structures are proposed as the stuffing of the sandwich structure and the bracing structure of fabric layer respectively, and the compression tests are finished. The congregating effect of the "Y" structures on the debris cloud is validated by the hypervelocity impact test. The projectile diameter is 5 mm, and the impact velocities range from 3.9 km/s to 4.3 km/s. According to the test results, the "Y" structures adhered on the plate have certain stability and could play the bracing role, and they can reduce even eliminate the congregating effect on the debris cloud, however, their yield strength is lower compared with the aluminum honeycomb structure of equivalent areal density, which could be solved by structure optimum. The study results provide reference for improving the honeycomb structure used on spacecraft shield. • "Y" structure is designed to eliminate channel effect of honeycomb core. • Compression and hypervelocity impact test validate the design idea. • "Y" structure has roles of bracing structure and dissipating energy. [ABSTRACT FROM AUTHOR]

To avoid agglomeration of ultrafine diamond particles and to improve machining precision of silicon (Si) wafers, a combination of gel casting and pore-forming agent is introduced to fabricate vitrified-bonded ultrafine diamond grinding wheel with ultrahigh porosity (~75%), honeycomb structure, and homogeneous microstructure. Moreover, the as-prepared grinding wheel possesses uniformly distributed closed pores, which are highly desirable for chip removal, heat dissipation and extended service life. In addition, influences of sintering schedules on microstructure, porosity and bending strength of the as-prepared grinding wheel are systematically investigated. Because of the honeycomb structure, the as-fabricated grinding wheel renders superior self-sharpness, which is required for continuous grinding of Si wafers without dressing, and this subsequently enhances the working efficiency. Results reveal that the surface roughness and damaged layer of the ground Si wafers are approximately 5.0 nm and 0.21 μm, respectively. The current study provides a novel pathway for efficiently processing high-quality silicon wafers. [ABSTRACT FROM AUTHOR]

Honeycomb structures exhibit outstanding mechanical properties with specific unit cell configurations. We introduce a novel honeycomb structure that can enhance the compression property and energy absorption capacity by utilizing four-dimensional (4D) printing technology with polylactic acid (PLA) materials. In the designed honeycomb structure, the walls of the adjacent unit cells are independent, and the shape of the unit cells can be transformed between a hexagon and triangle under external loading and temperature stimulus. 4D printing technology is employed to prepare the honeycomb specimens, and the deformation processes of the innovative honeycombs are implemented. Structure I (a novel hexagonal honeycomb structure) and Structure II (a semi-triangular honeycomb structure) can be transformed into each other. Uniaxial quasi-static compression and impact tests are conducted to investigate the compression property and energy absorption capacity of the designed honeycomb structures. The results indicate that the novel honeycomb had a high compression property with Structure II, and had high energy absorption capacity with Structure I; thus, the developed honeycomb structures have broad application prospects for the multifunctional applications of honeycomb structures in the future. [ABSTRACT FROM AUTHOR]

• A novel honeycomb structure with zero Poisson's ratio is proposed. • Relationships between three elastic constants and geometric parameters are studied. • The zero poisson's ratio property is maintained within a relatively small fluctuation range. The superior performance of honeycomb structure has facilitated its extensive application in various fields. In this paper, a novel honeycomb structure is proposed, which exhibits zero Poisson's ratio behavior. Firstly, the in-plane mechanical properties are analyzed based on the classical Castigliano's theorem to obtain expressions connecting the three elastic constants of the structure and geometric parameters. Then, the theoretical expressions are verified by homogenized finite element methods and 3D-printed experimental models, which help to determine the relationship between the in-plane mechanical properties and the geometric parameters. The results show that the mechanical properties of the honeycomb structure can be tailored by changing the geometric parameters, while ensuring that the zero Poisson's ratio property is maintained within a relatively small fluctuation range. This study reveals that the mechanical properties of the novel honeycomb structure are tunable, which has outperformed some honeycomb structures on adjusting range. [ABSTRACT FROM AUTHOR]

• A novel strategy was provided for preparing EM wave absorbing materials. • Oblique honeycomb Al 2 O 3 /SiCw structure was designed and synthesized. • 3D-printed designable structure can effectively affect EM wave absorption. For electromagnetic wave (EMW) absorption materials, combining microstructure design with macrostructure design is considered as an effective means to adjust EMW absorption performance. Undoubtedly, the great advantages of three-dimensional (3D) printing technology in structural design and accurate molding provide a convenient and feasible research scheme for the adjustment of EMW absorption performance. In this study, a method combined 3D printing technology with direct chemical vapor infiltration (CVI) has been adopted to fabricate Al 2 O 3 /SiC whisker (SiCw) honeycomb composites. The porous oblique honeycomb structures with well-designed angle (30°, 45°, 60° and 75°) and micron-scale SiCw effectively improved impedance match, inner scattering and dielectric loss, which resulted in the realization of the optimized wave absorbing composites. Specially, Al 2 O 3 /SiCw composite with the angle of 30° shows a minimum reflection coefficient (RC min) value of −63.65 dB (99.9999%) absorption at 9.8 GHz with a thickness of 3.5 mm while the effective absorption bandwidth (EAB) ranges from 8.2 to 12.4 GHz, covering the whole X band. Besides, the EMW absorption mechanism for 3D printed Al 2 O 3 /SiCw composite is also discussed. As a proof of concept, this strategy provides a novel and effective avenue to fabricate structural composites with broader and higher microwave absorption performance. [ABSTRACT FROM AUTHOR]

• Relative density of honeycomb structures greatly influences their blast response. • The crushing velocity depends on mass, impulse and relative density of the core. • The sacrificial cladding solutions exhibit promising energy dissipation capabilities. The increasing use of improvised explosive devices in terrorist attacks against civil targets has challenged the scientific community to find new strengthening or protective solutions, able to mitigate the effects of the blast loads. As a response to this demand, the present study investigates the nonlinear response of 3D printed PLA honeycomb structures in order to analyse their energy absorption capacity when used as the crushable core of a sacrificial cladding solution. The dynamic response of the proposed sacrificial solution is experimentally obtained by means of an explosive driven shock tube, while the corresponding numerical simulations are performed using the commercial finite element software LS-DYNA. Both the experimental and numerical data are in good agreement and clearly show that, as expected, the dynamic force plateau and the specific energy absorption is directly proportional to the considered relative density, which controls the crushing of the top and bottom layers of the PLA honeycomb and the buckling of its interior cell walls. When compared with other available materials, the analysed sacrificial cladding solutions exhibit promising values of energy dissipation and encourage future research in this area. [ABSTRACT FROM AUTHOR]

Highlights • Honeycomb-structured Co–W–B composite was prepared by simple chemical reduction. • The Co–W–B composite was mainly composed of oxides of Co, W, and as a result of oxidation in air. • The Co–W–B composite shows high surface area, large pore volume, and good stability. • The Co–W–B composite exhibited a specific capacitance of 306.3 F g–1 at a current density of 2 A g–1. Abstract A honeycomb-structured Co–W–B composite was prepared by a simple chemical reduction process in an alcohol solution. The structure and morphology of the Co–W–B composite was characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results indicate that the composite was mainly composed of oxides of Co, W, and B as a result of oxidation in air, and it was a suitable material for high-performance pseudocapacitors. Electrochemical tests indicated that the Co–W–B composite exhibited a specific capacitance of 306.3 F g–1 at a current density of 2 A g–1, which is much higher than that of a Co–B composite. Furthermore, the Co–W–B composite showed good stability, and the capacitance retained 89.2% of its initial capacitance after 2500 cycles. These results demonstrate that the honeycomb-structured Co–W–B composite is promising for use as an electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

Developing shape memory alloys (SMAs) with high strength and large recoverable strain is meaningful to broaden their application in extreme scenarios. In this work, a dual-SMA composite with bio-spired honeycomb structure, which consists of NiTi SMA matrix and NiTiZrCu SMA reinforcement, was designed and fabricated through the combination of 3D printing and hot extrusion. The utilization of honeycomb structure ensures uniform stress transmission and reducing the likelihood of stress concentration. The resulting microstructure, martensite transformation, and superelasticity were studied systematically. The dual-SMA composite exhibited a superior superelasticity with a remarkable recoverable strain higher than 5% and good recovery rate of 96% under a high external stress of 1.4 GPa. Fundamentally, the honeycomb structure in the dual-SMA composite facilitates the occurrence of progressive phase transformation process. The large recoverable strain and good recovery rate were attributed to the coupling effect of superelasticity and linear-elasticity throughout the whole loading process, which enables the dual-SMA composite to sustainably bear the load without undergoing plastic yielding. These findings make it available for designing and fabricating SMA composites with superior performance. [ABSTRACT FROM AUTHOR]

Excellent light absorption and suppressed salt crystallization are required for solar evaporators to operate continuously and efficiently. Herein, we report a waste biomass-derived solar evaporator (Le/CNTs-corn stalk) with natural 3D honeycomb structure and sustainable salt-resistance for efficient desalination and potential electricity generation. This simply fabricated 3D light-absorbing nanostructure greatly increases the light transmission distance, achieving significant boost in light absorption of 94.8 % and photothermal conversion efficiency of 92.5 %. Moreover, a spontaneous salt exchange capability between vascular bundles and laser engraved channels is developed according to the Hagen-Poiseuille's law. Salt concentration difference formed by the volume flowrate is alleviated to facilitate salt dissolution and prevent salt accumulation on the surface, enabling to evaporate effectively for 8 h even in 10 % salt solutions. In addition, tentatively inserted carbon nanotubes on its internal channel surface raises the total zeta potential and causes surface negative charge. A promising electricity generation potential is explored with continually generating a steady voltage of ∼136 mV. Our work provides a sustainable and massive strategy to realize efficient water production and simultaneous electricity generation using sufficient solar energy and biomass resources. • The natural 3D honeycomb structure enables light absorption up to 94.8 %. • Le/CNTs-corn stalk exhibits a high evaporation efficiency of 92.5 %. • It owns a spontaneous salt exchange capability. • It exhibits the potential for electricity generation. [ABSTRACT FROM AUTHOR]

The performed DFT study of the electronic structure of honeycomb Sb monolayer adsorbed on the Cu(111) surface has confirmed previous observations of significant role of tensile strain and related reduced buckling of adsorbed layer. The simulated STM pictures are perfectly consistent with those observed in experiment. We show that a significant band mixing with the substrate, which leads to an absence of occupied surface states at M point, questions applicability of the method of determination of the topological invariant Z 2 by means of estimates of the products of the parity eigenvalues. Hence, since the adsorption interaction with a metal surface is rather strong, the transformations of the bands of free honeycomb Sb layers with increasing lattice constants, which was recently suggested to cause the transition to the topological insulator state for certain range of the tensile strain, do not directly correspond to the changes which occur for adsorbed layers. • The electronic structure of Sb monolayers on Cu(111) is calculated with DFT. • A strong band mixing with the substrate leads to an absence of occupied surface states at M. • Strong interaction with substrate makes the products of the parity eigenvalues indefinite. • Interaction with the substrate precludes determination of the topological invariant Z2. [ABSTRACT FROM AUTHOR]

One of the most critical challenges in the field of hydrogen production through water electrolysis technique is the design, development and manufacture of electrode materials with low-cost, highly electrocatalytic activity and stability. We employ the galvanostatic deposition technique to prepare the honeycomb structured Co−Ni−Mo alloy electrocatalysts from ethylene glycol (EG) system, in which the honeycomb structure presents highly intrinsic electrocatalytic activity for hydrogen evolution reaction (HER). The electrochemical behavior of Co2+, Ni2+ and Mo6+ reductions and the co-deposition behavior of Co-Ni, Co-Mo, Ni-Mo and Co-Ni-Mo alloys is reported. Benefiting from the composition engineering by alloying with Mo atoms, as well as the simultaneous existence of a suitable honeycomb structure, these Co 58 Ni 23 Mo 19 deposits obtained at an optimal parameter exhibit prominent electrocatalytic durability and activity with a η 10 of 51 mV for HER in a 1.0 M KOH. More importantly, the formation model of the honeycomb structured Co-Ni-Mo alloy deposits is proposed. This work suggests a simple and economical method for the preparation of a 3-dimensional catalytic electrode. [Display omitted] • Co-deposition behavior of Co-Ni, Co-Mo, Ni-Mo and Co-Ni-Mo alloys in EG system is reported. • Co-Ni-Mo deposits with a honeycomb microstructure can be prepared from EG system. • Co 58 Ni 23 Mo 19 electrode presents a high electrocatalytic activity and stability for HER. • Formation model of the honeycomb structured Co-Ni-Mo deposits is proposed. [ABSTRACT FROM AUTHOR]

Hybrid organic-inorganic materials are of interest for a wide range of applications in fields of biotechnology, medical science, and green chemistry. In this study, we illustrated the principles of synthesis, the structure, and the functions of a novel konjac glucomannan (KGM) based biopolymer-silica hybrid materials. Nano-silicon dioxide (SiO 2 ) was applied as composites, combined with KGM, to form a highly porous structure by using a simple and versatile route – freeze drying. We systematically varied the Nano-SiO 2 concentration and solution pH value, the as-prepared organic-inorganic porous materials are highly ordered and highly strengthened with an average porous diameter of 100 μm, with honeycomb structure, tailored mechanical properties, and excellent support capacity. Activated carbon (AC)-loaded porous materials (CKNSi) exhibited a high Cu(II) adsorption capacity. [ABSTRACT FROM AUTHOR]

The hot deformation behavior and pulse current assisted diffusion bonding (PCDB) behavior of sintered γ-TiAl based alloy with near gamma microstructure were investigated for fabricating honeycomb structure via isothermal forging - PCDB route. Honeycomb core structures were fabricated via isothermal forging at 1150–1250 °C with a nominal strain rate of 10 −3 s −1 based on the hot deformation behavior of the sintered alloy. Additionally, the mechanical property and structural morphology demonstrated that the best forging parameter was forging at 1200 °C with a nominal strain rate of 10 −3 s −1 . Subsequently, the effects of bonding temperature, holding time, and bonding pressure on the microstructure evolution, plastic strain, and shear strength of the PCDB joints were investigated. The plastic strain and shear strength of the PCDB joints increased with increasing bonding temperature, time and stress, additionally, the fracture mode transformed from interfacial sliding fracture into substrate fracture with the optimization of bonding parameters. Furthermore, a sound metallurgical bonding joint with smaller plastic strain and shear strength as high as 92% of the base material was achieved at 1100 °C with a holding time of 20 min and a pressure of 25 MPa, showing priority compared to traditional hot pressing diffusion bonding process. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract We report the successful preparation of a purely honeycomb, graphene-like borophene, by using an Al(1 1 1) surface as the substrate and molecular beam epitaxy (MBE) growth in ultrahigh vacuum. Scanning tunneling microscopy (STM) images reveal perfect monolayer borophene with planar, non-buckled honeycomb lattice similar as graphene. Theoretical calculations show that the honeycomb borophene on Al(1 1 1) is energetically stable. Remarkably, nearly one electron charge is transferred to each boron atom from the Al(1 1 1) substrate and stabilizes the honeycomb borophene structure, in contrast to the negligible charge transfer in case of borophene/Ag(1 1 1). The existence of honeycomb 2D allotrope is important to the basic understanding of boron chemistry, and it also provides an ideal platform for fabricating boron-based materials with intriguing electronic properties such as Dirac states. [ABSTRACT FROM AUTHOR]

The properties of clay slurries (porosity ~ 0.75) impact a wide range of materials such as commercial clay dispersions and sedimentary deposits. Their material behavior, and in particular the gelation of clay slurries, is thought to be governed by clay particle interactions. In the literature, such interactions are rarely directly probed, but rather inferred from structures observed by cryo-electron microscopy. For example, the honeycomb structure is a widely accepted textbook model that is used to rationalize the observed behavior of clay slurries. Using high-pressure freezing, cryo-electron microscopy, and cryo-synchrotron wide-angle X-ray scattering, this study shows that the honeycomb-structure is an artifact of sample preparation. When samples are high-pressure frozen, individual clay particles and aggregates of particles arrange in a random orientation rather than the closed-cell structure dominated by face-face and face-edge contacts observed in plunge frozen samples. These results substantially contribute to the understanding of the gelation mechanism and particle interactions in colloidal clay slurries, and provide valuable input parameters for meso-scale modeling efforts of clay dispersions and sedimentary deposits to upscale their mechanical properties to the macroscale. [ABSTRACT FROM AUTHOR]

From the combined experimental and theoretical investigations, we suggest the formation of a honeycomb structure of BeO monolayer on the Mo(112) surface. This structure is matched to the substrate Mo(112), thus giving the (1 × 1) LEED pattern, and its formation is confirmed also by DFT calculations and work function measurements. While a free BeO monolayer is dielectric, the BeO/Mo(112) system is definitely metallic as follows from the bands crossing E F and significant density of states at E F . The honeycomb BeO monolayer is bound to the Mo(112) surface through O atoms situated atop Mo atoms of the surface rows. A substantial rigidity of the BeO monolayer leads to the appearance of empty space above the Mo(112) surface furrows, which may be filled by some gas or water molecules. Hence, this layered system can be very attractive in various applications where porous materials are explored (e.g. for hydrogen storage purposes). [ABSTRACT FROM AUTHOR]

Highly ordered, multi-layered, regular hexagonally patterned and size controlled honeycomb magnetic chitosan hydrogel beads were successfully fabricated by a facile method combining breath-figure templating and co-precipitation processing. The chitosan honeycomb beads were characterized and the unique structure formation mechanism was outlined. The diameter of pores in the hexagonally patterned structure was ∼10 μm, and the saturation magnetization of the chitosan honeycomb containing Fe 3 O 4 nanoparticles ( ca. 5 ± 2 nm) was around 12 emu/g. [ABSTRACT FROM AUTHOR]

• The well-formed honeycomb preform and composite were prepared and investigated. • HCWI composite with fine in situ TiC x framework exhibited excellent properties. • Transition zone owned high hardness, low friction coefficient, wear depth and EWF. The well-formed porous Ti 3 AlC 2 preform with honeycomb structure using mold forming method, and TiC x /high chromium white iron (TiC x /HCWI) composite with fine TiC x framework formed by porous Ti 3 AlC 2 preform in situ decomposition using pressureless infiltration method were successfully prepared, respectively. The HCWI composite with fine in situ TiC x framework exhibited excellent properties. The transition zone between framework and HCWI with the highest hardness, the minimum friction coefficient, wear depth and electronic work function (EWF) may protect the whole sample during wear. [ABSTRACT FROM AUTHOR]

[Display omitted] • A three-layer composite absorber composed of lossy material and artificial electromagnetic structure is proposed. • Magnetic coating can enhance the low-frequency absorption performance of composite absorber. • Pattern-impregnated honeycomb and resistive FSS jointly exhibit better impedance matching. • The fractional bandwidth of S 11 < −10 dB reaches 158.9% with a relative thickness of 0.6 λ L. • A maximum mechanical tensile stress of 67.43 MPa is obtained. In order to realize electromagnetic stealth of large equipment, we propose a low-cost, mass-producible composite microwave absorber in this paper. The developed novel EM absorber comprises a pattern-impregnated honeycomb structure with the absorbent of carbon black (CB), a resistive frequency selective surface (FSS) embedded in polypropylene (PP) foam, and a mixture coating covered on a metal plane whose absorbent is flaky carbonyl iron (FCI). CB particles and FCI particles provide electrical and magnetic losses at the microscopic scale. Moreover, the subwavelength-scale artificial electromagnetic structure achieves broadband matching to free space by adjusting macroscopic geometric parameters. The consistency between measurements and simulations proves that the composite absorber achieves over 90% absorption ratio with a thickness of 8.3 mm from 2.06 to 18 GHz (corresponding to a fractional bandwidth of 158.9%). Additionally, this composite absorber possesses good mechanical property with a maximum uniaxial tensile stress of 67.43 MPa. [ABSTRACT FROM AUTHOR]

In this paper, we compare the cell growth results of NIH-3T3 and Neuro-2A cells over 72 h on flat and honeycomb structured PLA films without and with a two-step atmospheric-pressure nitrogen-based plasma jet treatment. We developed a fabrication system used for forming of a uniform honeycomb structure on PLA surface, which can produce two different pore sizes, 3–4 μm and 7–8 μm, of honeycomb pattern. We applied a previously developed nitrogen-based atmospheric-pressure dielectric barrier discharge (DBD) jet system to treat the PLA film without and with honeycomb structure. NIH-3T3 and a much smaller Neuro-2A cells were cultivated on the films under various surface conditions. The results show that the two-step plasma treatment in combination with a honeycomb structure can enhance cell growth on PLA film, should the cell size be not too smaller than the pore size of honeycomb structure, e.g., NIH-3T3. Otherwise, cell growth would be better on flat PLA film, e.g., Neuro-2A. [ABSTRACT FROM AUTHOR]

Honeycombed iron doped graphitic carbon nitride with outstanding N 2 photofixation ability is synthesized in this work. Characterization results indicate that Fe 3+ inserts at the interstitial position and is stabilized in the electron-rich g-C 3 N 4 through the coordinative Fe-N bonds. Fe 3+ sites can chemisorb and activate N 2 molecules, then transfer the photogenerated electrons from the g-C 3 N 4 to adsorbed N 2 molecules. Fe0.05-CN displays the highest NH 4 + generation rate, which is approximately 13.5-fold higher than that of neat g-C 3 N 4 . Density functional theory simulations prove the N 2 activation effect of Fe 3+ sites due to the high adsorption energy and prolonged N N bond. Charge density difference result confirms the electrons transfer process from the Fe 3+ doping sites to N 2 molecule. DOS results indicate that the electrons of σ g 2p orbital (HOMO) in nitrogen atom is delocalized significantly when N 2 adsorbed on Fe 3+ doping sites, leading to its orbital energy almost connects to that of π g * 2p orbital (LUMO), which confirming that Fe 3+ doping sites can activate the N 2 molecule effectively. The Mulliken charge of nitrogen is −3.1 when the N 2 adsorbed on Fe 3+ doping sites, indicating that N 2 molecule is enriched by large number of electrons, which is beneficial to the H + attack to form NH 4 + . [ABSTRACT FROM AUTHOR]

Developing non-noble metal catalysts with high oxygen-permeability and activity for oxygen reduction reaction (ORR) is crucial for microbial fuel cells (MFCs). In this study, nitrogen-doped molybdenum disulfide/carbon (N-MoS 2 /C) is prepared using melamine as nitrogen and carbon sources. Ammonium molybdate, thiourea and Pluronic F127 are used as Mo source, S source and surfactant, respectively. Mo-S-melamine complex precursor is obtained through the evaporation-induced self-assembly route, which is then carbonized at 800, 900 and 1000 °C to fabricate N-MoS 2 /C. Defect-rich N-MoS 2 /C has a large number of exposed active sites and a high oxygen permeability. N-MoS 2 /C (900 °C) with regular honeycomb structure shows the maximum power density of 0.815 W m -2 , which is far higher than that of Pt/C (0.520 W m -2 ) and only has a decline of 1.23% after 1800 h operation in MFCs. Four-electron (4e − ) reduction of O 2 is the main ORR pathway for N-MoS 2 /C (900 °C), attributing to the efficient permeation, adsorption, activation and reduction of O 2 on the active sites. The synergy among abundant defects, N-species (pyridinic N, graphitic N and Mo−N x ) and high conductivity contributes to the promising ORR activity. This simple synthetic route of N-doped metal sulfides/carbon composites displays a new prospect for preparation of ORR catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spinal interbody cages adapted for an auxetic, and honeycomb using standard CAD software operations and manufactured with SLM. • Auxetic-based cages exhibit higher strength properties than honeycomb-based cages. • The stiffness of the auxetic cages is comparable to stiffness of human cortical bone. • The honeycomb cages exhibit lower value of Young's modulus closer to that for vertebrae. This paper presents a method for modeling a biomedical device by adaptation a commercially available interbody cage for an auxetic metamaterial and honeycomb structure using standard operations in Computer-Aided design software. The mechanical properties of experimental prototypes of Ti-6Al-4 V cages made by selective laser melting using computer modeling (finite element analysis), static and low-cycle fatigue compression tests (up to 3500 cycles) are characterized. 3D printed cells with structures with an angle of inclination between cell edges of less than 90˚ (auxetic metamaterial) are shown to exhibit higher static compressive strength and fatigue resistance than cells based on structures with an angle of inclination greater than 90˚ (honeycomb structure). The changes in the inclination angle differently affect to the porosity and consequently to mechanical behavior of auxetic metamaterial and honeycomb structure. The Young modulus of the auxetic-based interbody cage is 6.68 ± 0.28 GPa and comparable to the elastic modulus of human cortical bone. The honeycomb-based cage exhibits lower values of Young modulus (1.19 ± 0.03 GPa) close to that of trabecular bone and vertebrae. Importantly, the auxetic-based cage is not destroyed after 3500 cycles under 14 kN load with residual deformations ≤ 1 % (0.21 ± 0.10 mm displacements). [ABSTRACT FROM AUTHOR]

Local scour induced by current or wave is a significant factor impacting the overall stability and fatigue life of the pile foundation of wind turbines. Currently, the most commonly used scour protection method is the rock armour, which works by placing rocks on the original seabed to reduce the near-bottom flow speed. Although the rock armour is easy to be implemented in practice, it still has the potential of complete failure due to the washout near the structure and along the outer edge. In this study, we investigate the performance of four different scour protection methods through physical experiments, which include rock amour, sand-ribbed geotextile mattress (SRGM), bionic grass, and honeycomb structure. The results indicate that the sand-ribbed geotextile mattress is the most effective among all test scour protection methods. However, given its relatively high potential to impact local environment, careful and thorough consideration should be taken before the practical implementation. • Experiments are performed to evaluate the performance of scour protection methods. • The dynamic design of rock armour outperforms the static design. • The negative impacts of sand-ribbed geotextile mattress need further attention. • Wider bionic grasses are more favorable to the scour protection. • The honeycomb structure with smaller compartments has a better performance. [ABSTRACT FROM AUTHOR]

Development of lightweight ceramic aerogel with enhanced thermal insulation and high temperature resistance is required in the field of thermal insulation. Here, a aerogel-like SiOC ceramic with honeycomb structure was prepared by solvothermal method using polyhydromethylsiloxane (PHMS) as precursor and divinylbenzene (DVB) as cross-linker followed by freeze-drying and pyrolysis. The pore size and homogeneity of the honeycomb structure could be further controlled by the content of DVB through adjusting the crosslinking degree of the PSO wet gel. The aerogel-like SiOC possessing uniform honeycomb structure with the pore size of 20–50 µm and the wall thickness of 3–6 µm is obtained at the mass ratio of DVB:PHMS of 2:1. The aerogel-like SiOC exhibits low density (0.14 g·cm−3) and low thermal conductivity (0.0577 W·m−1·K−1). Moreover, it maintains the honeycomb structure after high temperature treatment at 1400 °C in argon and 800 °C in air indicating its good thermal stability. This work provides a novel route for the preparation of the aerogel-like SiOC ceramic with honeycomb structure and designable overall performance, further expanding its application in thermal insulation. • A novel strategy for developing lightweight aerogel-like SiOC ceramic with honeycomb structure is reported. • Controlling honeycomb-like structure by DVB content. • Realizing low thermal conductivity of 0.0577 W·m−1·K−1. • Achieving good thermal stability of structure at 1400 °C in Ar. [ABSTRACT FROM AUTHOR]

3D printing of magnetorheological elastomers (MREs) can potentially create versatile and complex mechanical structures with reversible stiffening properties. Several additive manufacturing (AM) methods, like direct printing and stereolithography (SLA), have been used to achieve magnetic thermoset and elastomer composite structures. For the first time, we demonstrate the use of MREs based on thermoplastic elastomers (TPE) in AM and we investigate their magnetorheological (MR) effect when used in lightweight honeycomb designs. Due to the low shore hardness of TPE, a screw extruder-based printing head is employed to print disk-shaped samples with honeycomb patterns at infill percentages varying from 15% to 50%. In order to compare the MR effect of disks with varying honeycomb infills through a compression method, we investigated the effect of different testing configurations. We observe that different permanent magnet configurations, as it has been used in literature so far, create an additional effect on the measured MR effect of the MRE samples. To eradicate this effect, a test setup with an unpaired permanent magnet configuration is proposed. MRE structures with an infill density of 20% showed, at 1% deformation range, the highest MR effect, almost four times as high as 100% infilled samples. MRE structures with an infill density between 30% and 50% showed a lower MR effect than at 20%, but were still higher than at 100%. We observe in simulations that the magnetic flux density of 100% infilled samples was higher at the edges of the samples and lower at the center. For samples with honeycomb infill, the magnetic flux density was higher at the outer rim of the samples and edges of the walls within the sample, which causes a higher MR effect. Our work demonstrates that the MR effect can be tuned by designing a MRE structure with a honeycomb infill. The honeycomb infill results in lightweight MREs with improved MR effect useful for various downstream applications that require reversible strong stiffening while remaining comparatively lightweight. [Display omitted] • Light-weight magnetorheological structures made with additive manufacturing. • Step-by-step study of magnetorheological characterization under compression mode. • Paired permanent magnets leads to overestimated magnetorheological (MR) effect. • Effect of varying honeycomb patterned infill density on MR effect was investigated. • Magnetorheological structures with lowest infill shows the highest MR effect. [ABSTRACT FROM AUTHOR]

Modified honeycomb parts of Ni-15Fe-5Mo permalloy for magnetic shielding applications were designed and fabricated via laser powder bed fusion (L-PBF) 3D printing. We focused on the L-PBF process and performances of the thin-walled samples with different overhangs. After temperature-field numerical simulations and mechanism analyses on the L-BPF molten pools, the process optimizations were conducted to achieve a high bulk relative density. The thin walls with different wall thicknesses (0.3, 0.4, 0.5, 0.6, 0.7, and 0.8 mm) and overhanging angles (10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, and 90°) were printed without any supporting struts. The structures, mechanical properties, and formation mechanisms of the thin-walled overhangs were studied. We roughly gained some such trends or inferences about the tensile properties of the thin-walled overhangs. The microstructural anisotropies and surface "step effects" were the primary factors affecting the tensile properties. The numerical simulation and experiment of compression on the modified honeycomb parts with several sidewall inclination angles were performed. The modified honeycomb structures transferred stress and premature failure to other local structures far away from the compression face. The preferential plastic deformation of the modified honeycomb structures occurred at the inclined corners, exhibiting good plastic deformation buffering effect and thus avoiding instantaneous cracking. This work presented some reference significance for high-quality formation and performance evaluation of thin-walled overhanging structures via L-PBF. • Permalloy thin-walled overhangs were 3D-printed without any supporting struts. • Modified honeycomb thin-walled parts for magnetic shield were L-PBF-printed. • Tensile properties of as-printed thin-walled overhangs were comparatively tested. • Numerical simulation and testing were performed on modified honeycomb parts. • Physical mechanism analysis were conducted on printed thin-walled formability. [ABSTRACT FROM AUTHOR]

In this paper, we synthesize honeycomb structure titanium dioxide (TiO 2) grafted with carbon fiber (CF) composites (CF/TiO 2) for flexible supercapacitors (SCs), which evidently boosts specific surface areas (SSA) of CF. In addition, we put forward an effective strategy for enhancing conductivity of TiO 2 relying on construction of oxygen defects in NaBH 4 solution. Amazingly, the reduced-TiO 2 supporting on CF electrode (CF /R–TiO 2) obtains from optimum conditions (2 M 4h) and exhibits the highest specific capacitance of 115.2 F g−1 at 1200 mA g−1, suggesting ultra-utilization of R–TiO 2 for SC. Interestingly, its capacitance retention still remains 98.37% after 10000 cycles, which declares prominent cycling stability. Furthermore, we conduct density functional theory (DFT) analysis to reveal the enhancement mechanism of R–TiO 2. With the reduction process, Fermi energy (E F) can obviously move conduction band (CB), which indicates increments of electronic conductivity of TiO 2. Moreover, the aqueous symmetric SC based on CF/R–TiO 2 (CF/R–TiO 2 -SC) expresses a high energy density of 49.6 Wh kg−1 at a power density of 1440 W kg−1. Meanwhile, the all-solid-state flexible supercapacitor (CF/R–TiO 2 -AFSC) further presents favorable flexibility in tested bending angles. Our results demonstrate that CF/R–TiO 2 is provided with introduction of oxygen defects and honeycomb structure, which might have tremendous potential for SC. [Display omitted] • Honeycomb structure TiO 2 with oxygen defects was designed for supercapacitors. • Oxygen defects were introduced into TiO 2 by one-step NaBH 4 reduction. • Flexible CF/R–TiO 2 -SC exhibited the remarkable energy density of 48.4 Wh kg−1. • The CF/R–TiO 2 -AFSC could show favorable flexibility. [ABSTRACT FROM AUTHOR]

• The electronic structure of Sb honeycomb layer on Ag(111) is calculated with relativistic DFT. • The formation of the honeycomb structure and its stability are studied by performed Monte Carlo simulations. • The bands crossing E F loose the surface weight away from K point, so that they are not localized in the Sb adlayer in the net Brillouin zone. The electronic structure of the Sb layer on Ag(111), recently reported to have a flat (√3 × √3) honeycomb structure similar to that of graphene [Y. Shao et al. , Nano Lett. (2018) 18:2133–9], is studied by means of relativistic DFT calculations. In accordance with earlier results, a flat free Sb monolayer is found to be metastable, as follows from the existence of an imaginary phonon mode. The layer spontaneously reconstructs into a buckled honeycomb structure, which leads to the metal-to-nonmetal transition. It is suggested therefore that the formation of a flat Sb honeycomb layer becomes possible just because of the substrate-induced tensile strain, which results in the stabilization of the structure. The binding (adsorption) energy per Sb atom for the honeycomb structure is found to be rather strong, 4.61 eV, which can be explained by a significant lateral attraction between Sb adatoms. The formation of the honeycomb structure and its stability are studied by performed Monte Carlo simulations within the lattice-gas model either with account for trio interactions, or with some effective energy parameters. The SOC only slightly changes the band structure of the system, but, due to pronounced downward shift of the cone-like band in vicinity of K point, leads to the second surface band crossing E F. A detailed analysis of the localization of the wave functions indicates that the bands crossing E F loose the surface weight away from K point, so that they are not localized in the Sb adlayer in the net Brillouin zone. Left: The snapshots and related LEED patterns obtained in the course of Monte Carlo simulations, Right: The band structure of the honeycomb Sb monolayer on Ag(111). The localization of the wave functions for a few characteristic states is illustrated by electron density distributions shown in inserts. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-folded honeycomb structure (SHS) was fabricated via stimuli-responsive materials. • Origami-inspired design for SHSs with energy-absorption properties was established. • Relationship of design, structure, and compression performance was elucidated. • Energy-absorption of 5-layered SHS was 6.67 times higher than that of 1-layered SHS. • Damage factor for protected object was successfully removed via pre-straining. The origami technique has been employed in the medical, space, and agricultural industries owing to its low cost and ease of use. In particular, the use of stimuli-responsive materials to automate origami fabrication has garnered interest. In this study, self-folded honeycomb structures (SHSs) were fabricated using the self-folding technique. A sheet of paper undergoes self-folding without human intervention via the physicochemical reactions between the paper and printing solution. Six SHSs with different mechanical properties were fabricated. The relationship between the design and structural parameters was examined. The energy-absorption performance of the structure improved by a factor of 15.2 on employing the optimal parameters. A consistent relationship between the design and compression performance was also discussed. By applying stacking technology, the energy-absorption performance increased by an average of 1753 N·mm per layer. The application of a pre-strain eliminated the compressive force peak that could damage the protected object, while maintaining 90 % of the energy-absorption performance. The proposed technology shows potential for the fabrication of tailored energy absorbers using stimuli-responsive materials, providing a groundbreaking technology for the packaging industry. [ABSTRACT FROM AUTHOR]

We have used infrared thermography to study water trapped in aviation honeycomb panels, namely: 1) possibility of quantitative evaluation of trapped water, 2) influence of honeycomb panel orientation on the efficiency of water detection, and 3) discrimination between honeycomb cells filled with water and adhesive. It is shown, both theoretically and experimentally, that it is difficult for TNDT to discriminate between the presence of water and epoxy trapped in honeycomb cells, by analyzing only the surface temperature patterns. It has been demonstrated that water trapped in honeycomb cells can be reliably detected by an increase in effusivity starting from the inflection time. This process is referred to as the “concept of apparent effusivity”. [ABSTRACT FROM AUTHOR]