Honeycomb structures, inspired from bee honeycombs, had found widespread applications in various fields, including architecture, transportation, mechanical engineering, chemical engineering, ...nanofabrication and, recently, biomedicine. A major challenge in this field is to understand the unique properties of honeycomb structures, which depended on their structures, scales and the materials used. In this article, we presented a state-of-the-art review of the interdisciplinary efforts to better understand the design principles for products with honeycomb structures, including their fabrication, performance (e.g., mechanical, thermal and acoustic properties) as well as optimization design. We described how these structural perspectives have led to new insights into the design of honeycomb structures ranging from macro-, micro- to nano-scales. We presented current scientific advances in micro- and nano-technologies that hold great promise for bioinspired honeycomb structures. We also discussed the emerging applications of honeycomb structures in biomedicine such as tissue engineering and regenerative medicine. Understanding the design principles underlying the creation of honeycomb structures as well as the related scientific discovery and technology development is critical for engineering bioinspired materials and devices designed based on honeycomb structures for a wide range of practical applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In order to improve the brittle characteristics of coral cement-based composites and increase their toughness, an experimental study was carried out on the basic mechanical properties of PVA ...(polyvinyl alcohol) fiber-reinforced coral cement-based composites, taking into account the fiber content and length-to-diameter ratio (L/D). The results showed that PVA fibers can effectively improve the mechanical properties of concrete, especially its tensile strength. At the same time, PVA fibers improved the damage characteristics of cement-based composites and had obvious toughening and brittleness reduction effects. The PVA fibers, with a volume content of 1.5% and an L/D of 225, had the best performance in reinforcing the overall performance of the coral cement-based composites. Too many PVA fibers or a large length-to-diameter ratio would make it difficult for the fibers to contribute to toughness and cracking resistance and even cause defects in the matrix, reducing the mechanical properties. The tensile stress-strain curves of PVA fiber-reinforced coral cement-based composites were consistent with the trilinear constitutive model curves and showed the tensile characteristic of strain hardening after the occurrence of the main cracks.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In this work, the impact of temperature on the crushing performance of multi-walled tube (MWT) were investigated using a combined experimental, theoretical and numerical method. The MWT was ...fabricated using extrusion technology, and the temperature-dependent axial crushing experiment was performed on a hydraulic testing machine. The results show that the peak crushing force (PCF), the mean force (Pm) and the specific energy absorption (SEA) decreased near-linearly by 21.7%, 30.7% and 30.7% as the temperature increased from 25 °C to 250 °C, while the crushing load efficiency (CLE) was insensitive to temperature. The average forces obtained via numerical prediction, theoretical analysis and experimental testing were basically consistent. The numerical results indicate that varied temperature alters the number of dominant wavelets and the relative lateral deflections of MWT. In addition, compared with the competitive structures, the energy absorption property of MWT is excellent at high temperatures.
In the previous study, the cellulolytic Escherichia coli ZH-4 isolated from bovine rumen was found to show extracellular cellulase activity and could degrade cellulose in the culture. The goal of ...this work was to identify and characterize the secreted cellulase of E. coli ZH-4. It will be helpful to re-understand E. coli and extend its application in industry.
A secreted cellulase was confirmed to be endo-glucanase BcsZ which was encoded by bcsZ gene and located in the cellulose synthase operon bcsABZC in cellulolytic E. coli ZH-4 by western blotting. Characterization of BcsZ indicated that a broad range of pH and temperature tolerance with optima at pH 6.0 and 50 °C, respectively. The apparent Michaelis-Menten constant (K
) and maximal reaction rate (V
) for BcsZ were 8.86 mg/mL and 0.3 μM/min·mg, respectively. Enzyme activity of BcsZ was enhanced by Mg
and inhibited by Zn
, Cu
and Fe
. BcsZ could hydrolyze carboxymethylcellulose (CMC) to produce cello-oligosaccharides, cellotriose, cellobiose and glucose.
It is confirmed that extracellular cellulolytic capability of E. coli ZH-4 was attributed to BcsZ, which explained why E. coli ZH-4 can grow on cellulose. The endo-glucanase BcsZ from E. coli-ZH4 has some new characteristics which will extend the understanding of endo-glucanase. Analysis of the secretion characteristics of BcsZ provided a great reference for applying E. coli in multiple industrial fields.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Ultralight sandwich constructions with corrugated channel cores (i.e., periodic fluid-through wavy passages) are envisioned to possess multifunctional attributes: simultaneous load-carrying and heat ...dissipation via active cooling. Titanium alloy (Ti-6Al-4V) corrugated-channel-cored sandwich panels (3CSPs) with thin face sheets and core webs were fabricated via the technique of selective laser melting (SLM) for enhanced shear resistance relative to other fabrication processes such as vacuum brazing. Four-point bending responses of as-fabricated 3CSP specimens, including bending resistance and initial collapse modes, were experimentally measured. The bending characteristics of the 3CSP structure were further explored using a combined approach of analytical modeling and numerical simulation based on the method of finite elements (FE). Both the analytical and numerical predictions were validated against experimental measurements. Collapse mechanism maps of the 3CSP structure were subsequently constructed using the analytical model, with four collapse modes considered (face-sheet yielding, face-sheet buckling, core yielding, and core buckling), which were used to evaluate how its structural geometry affects its collapse initiation mode.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The functional role of collagen piezoelectricity has been under debate since the discovery of piezoelectricity in bone in 1957. The possibility that piezoelectricity plays a role in bone remodeling ...has generated interest in the investigation of this effect in relevant physiological conditions; however, there are conflicting reports as to whether collagen is piezoelectric in a humid environment. In macroscale measurements, the piezoelectricity in hydrated tendon has been shown to be insignificant compared to dehydrated tendon, whereas, at the nanoscale, the piezoelectric effect has been observed in both dry and wet bone using piezoresponse force microscopy (PFM). In this work, the electromechanical properties of type I collagen from a rat tail tendon have been investigated at the nanoscale as a function of humidity using lateral PFM (LPFM) for the first time. The relative humidity (RH) was varied from 10% to 70%, allowing the piezoelectric behavior to be studied dry, humid, as well as in the hydrated range for collagen in physiological bone (12% moisture content, corresponding to 40–50% RH). The results show that collagen piezoresponse can be measured across the humidity range studied, suggesting that piezoelectricity remains a property of collagen at a biologically relevant humidity.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The concept of combining metallic honeycomb with folded thin metallic sheets （corrugation） to construct a novel core type for lightweight sandwich structures is proposed. The honeycomb-corrugation ...hybrid core is manufactured by filling the interstices of aluminum corrugations with precision-cut trapezoidal aluminum honeycomb blocks, bonded together using epoxy glue. The performance of such hybrid-cored sandwich panels subjected to out-of-plane compression, transverse shear, and three-point bending is investigated, both experimentally and numerically. The strength and energy absorption of the sandwich are dramatically enhanced, compared to those of a sandwich with either empty corrugation or honeycomb core. The enhancement is induced by the beneficial interaction effects of honeycomb blocks and folded panels on improved buckling resistance as well as altered crushing modes at large plastic deformation. The present approach provides an effective method to further improve the mechanical properties of conventional honeycomb-cored sandwich constructions with low relative densities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Two-dimensional (2D) metal borides are a class of ceramic materials with diverse structural and topological properties. These diverse material properties of metal borides are what forms the basis of ...their interdisciplinarity and their applicability in various research fields. In this study, we highlight which fundamental and practical parameters need to be taken into consideration when designing nanomaterials for specific applications. A simple one-pot chemical reduction method was applied for the synthesis of manganese mono-boride nanoflakes at room temperature. How the specific surface area and boron-content of the as-synthesized manganese mono-boride nanoflakes influence their magnetic and electrocatalytic properties is reported. The sample with the highest specific surface area and boron content demonstrated the best magnetic and electrocatalytic properties in the HER. Whereas the sample with the lowest specific surface area and boron content exhibited the best electric conductivity and electrocatalytic properties in the OER.
Titanium dioxide （TiO2） is widely employed as a solid photocatalyst for solar energy conversion and envi- ronmental remediation. The ability to construct porous TiO2 with controlled particle size and ...narrowed bandgap is an essential requirement for the design of highly efficient and recyclable photocatalysts. Here, we report a template- free acetic acid induced method for the synthesis of visible- light responsive carbon-doped TiO2 microplates with high crystallinity and mesoporous structure. It is shown that the electron-withdrawing bidentate carboxylate ligands derived from acetic acid can narrow the bandgap of TiO2 （1.84 eV） substantially. Moreover, the resultant microplate photo- catalysts exhibit excellent photocatalytic efficiency and solid-liquid separation performance, which will be bene- ficial for future industrial applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UL, UM, UPCLJ, UPUK, VKSCE, ZAGLJ, ZRSKP
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